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Sample records for beir vi study

  1. Status report on the National Research Council`s BEIR VI study

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    Douple, E.

    1995-10-01

    The objectives of the committee on Biological Radiation Effects of Ionizing Radiation VI (BEIR) are to : assist the EPA in phase I by collecting and evaluating information on ongoing studies and results of studies published since the BEIR VI report of 1988 on the health effects of exposure to radon progeny; to perform a full scale reassessment of the health effects if a phase II study is warranted on the basis of phase I results. The BEIR VI working groups consists of miner data sets and analysis; residential studies; smoking and nonsmoking interactions; exposure and dosimetry; cellular and molecular studies; risk models and uncertainties; and animal studies.

  2. BEIR-III controverly

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    Fabrikant, J.I.

    1980-06-01

    How certain of the areas addressed by the Committee on the Biological Effects of Ionizing Radiation (BEIR) have attempted to deal with the scientific basis for establishing appropriate radiation protection guides is discussed, and what effect this may have on decision-making for the regulation of societal activities concerned with the health effects in human populations exposed to low-level radiation. (ACR)

  3. Studies in Sulphonamides - Part VI

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    G. S. Saharia

    1972-04-01

    Full Text Available Five different 1:3-diaryl propane-1:3-diones, 1-(m-nitrophenyl-3-phenyl-, 1-(m-nitrophenyl-3-(p-methoxyphenyl-, 1-(p-methoxyphenyl-3-(p-bromophenyl-and 1-(pmethoxyphenyl-3-(p-chorophenyl propane-1:3-diones have been synthesised and coupled with eight different diazotised sulphonamide bases to give 1:3-diary 1-2(substituted sulphonamidobenzeneazo propane-1:3-dicnes. The pharmacological properties of all these azo-compounds have been studied in vitro by the cup-plate method.

  4. A comparison of radiological risk assessment models: Risk assessment models used by the BEIR V Committee, UNSCEAR, ICRP, and EPA (for NESHAP)

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    Wahl, L.E.

    1994-03-01

    Radiological risk assessments and resulting risk estimates have been developed by numerous national and international organizations, including the National Research Council`s fifth Committee on the Biological Effects of Ionizing Radiations (BEIR V), the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), and the International Commission on Radiological Protection (ICRP). A fourth organization, the Environmental Protection Agency (EPA), has also performed a risk assessment as a basis for the National Emission Standards for Hazardous Air Pollutants (NESHAP). This paper compares the EPA`s model of risk assessment with the models used by the BEIR V Committee, UNSCEAR, and ICRP. Comparison is made of the values chosen by each organization for several model parameters: populations used in studies and population transfer coefficients, dose-response curves and dose-rate effects, risk projection methods, and risk estimates. This comparison suggests that the EPA has based its risk assessment on outdated information and that the organization should consider adopting the method used by the BEIR V Committee, UNSCEAR, or ICRP.

  5. Risk estimation and decision-making: implications of the 1980 BEIR-III report

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    Fabrikant, J.I.

    1981-04-01

    The report gives a general background of the implications the current Report of the Committee on the Biological Effects of Ionizing Radiation (The BEIR-III Report) may have on societal decision-making in the regulation of activities concerned with the health effects of low-level radiation. (ACR)

  6. BEIR-III report and its implications for radiation protection and public health policy

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    Fabrikant, J.I.

    1980-03-01

    A general background is given of the implications the BEIR-III Report may have on societal decision-making in the regulation of activities concerned with the health effects of low-level radiation. The scientific basis for establishing appropriate radiation protection guides are discussed. (ACR)

  7. BEIR-III report and the health effects of low-level radiation

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    Fabrikant, J.I.

    1980-01-01

    The present BEIR-III Committee has not highlighted any controversy over the health effects of low-level radiation. In its evaluation of the experimental data and epidemiological surveys, the Committee has carefully reviewed and assessed the value of all the available scientific evidence for estimating numerical risk coefficients for the health hazards to human populations exposed to low levels of ionizing radiation. Responsible public awareness of the possible health effects of ionizing radiations from medical and industrial radiation exposure, centers on three important matters of societal concern: (1) to place into perspective the extent of harm to the health of man and his descendants to be expected in the present and in the future from those societal activities involving ionizing radiation; (2) to develop quantitative indices of harm based on dose-effect relationships; such indices could then be used with prudent caution to introduce concepts of the regulation of population doses on the basis of somatic and genetic risks; and (3) to identify the magnitude and extent of radiation activities which could cause harm, to assess their relative significance, and to provide a framework for recommendations on how to reduce unnecessary radiation exposure to human populations. The main difference of the BEIR Committee Report is not so much from new data or new interpretations of existing data, but rather from a philosophical approach and appraisal of existing and future radiation protection resulting from an atmosphere of constantly changing societal conditions and public attitudes. (PCS)

  8. Mechanism of Cr(VI) adsorption by coir pith studied by ESR and adsorption kinetic.

    Science.gov (United States)

    Suksabye, Parinda; Nakajima, Akira; Thiravetyan, Paitip; Baba, Yoshinari; Nakbanpote, Woranan

    2009-01-30

    The oxidation state of chromium in coir pith after Cr(VI) adsorption from aqueous solution was investigated using electron spin resonance (ESR). To elucidate the mechanism of chromium adsorption on coir pith, the adsorption studies of Cr(VI) onto lignin, alpha-cellulose and holocellulose extracted from coir pith were also studied. ESR signals of Cr(V) and Cr(III) were observed in coir pith adsorbed Cr(VI) at solution pH 2, while ESR spectra of lignin extracted from coir pith revealed only the Cr(III) signal. In addition, ESR signal of Cr(V) was observed in alpha-cellulose and holocellulose extracted from coir pith adsorbed Cr(VI). These results confirmed that lignin in coir pith reduced Cr(VI) to Cr(III) while alpha-cellulose and holocellulose extracted from coir pith reduced Cr(VI) to Cr(V). The Cr(V) signal exhibited in ESR of alpha-cellulose and holocellulose might be bound with glucose in cellulose part of coir pith. In addition, xylose which is main in pentosan part of coir pith, indicated that it is involved in form complex with Cr(V) on coir pith. The adsorption kinetic of Cr(VI) from aqueous solution on coir pith was also investigated and described well with pseudo second order model. ESR and desorption experiments confirmed that Cr(VI), Cr(V) and Cr(III), exist in coir pith after Cr(VI) adsorption. The desorption data indicated that the percentage of Cr(VI), Cr(V) and Cr(III) in coir pith were 15.63%, 12.89% and 71.48%, respectively.

  9. Mechanism of Cr(VI) adsorption by coir pith studied by ESR and adsorption kinetic

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    Suksabye, Parinda [Joint Graduate School of Energy and Environment, King Mongkut' s University of Technology Thonburi, 91 Pracha-Utit Road, Bangmod, Thungkru, Bangkok 10140 (Thailand); Nakajima, Akira [Division of Chemistry, Department of Medical Science, Faculty of Medicine, University of Miyazaki, Kiyotake, Miyazaki 889 1692 (Japan); Thiravetyan, Paitip [Division of Biotechnology, School of Bioresources and Technology, King Mongkut' s University of Technology Thonburi, 83 Moo.8 Thakham, Bangkhuntien, Bangkok 10150 (Thailand)], E-mail: paitip.thi@kmutt.ac.th; Baba, Yoshinari [Department of applied Chemistry, Faculty of Technology, University of Miyazaki, Gakuen-Kibabadai, Miyazaki 889 2192 (Japan); Nakbanpote, Woranan [Pilot Plant Development and Training Institute, King Mongkut' s University of Technology Thonburi, 83 Moo.8 Thakham, Bangkhuntien, Bangkok 10150 (Thailand)

    2009-01-30

    The oxidation state of chromium in coir pith after Cr(VI) adsorption from aqueous solution was investigated using electron spin resonance (ESR). To elucidate the mechanism of chromium adsorption on coir pith, the adsorption studies of Cr(VI) onto lignin, {alpha}-cellulose and holocellulose extracted from coir pith were also studied. ESR signals of Cr(V) and Cr(III) were observed in coir pith adsorbed Cr(VI) at solution pH 2, while ESR spectra of lignin extracted from coir pith revealed only the Cr(III) signal. In addition, ESR signal of Cr(V) was observed in {alpha}-cellulose and holocellulose extracted from coir pith adsorbed Cr(VI). These results confirmed that lignin in coir pith reduced Cr(VI) to Cr(III) while {alpha}-cellulose and holocellulose extracted from coir pith reduced Cr(VI) to Cr(V). The Cr(V) signal exhibited in ESR of {alpha}-cellulose and holocellulose might be bound with glucose in cellulose part of coir pith. In addition, xylose which is main in pentosan part of coir pith, indicated that it is involved in form complex with Cr(V) on coir pith. The adsorption kinetic of Cr(VI) from aqueous solution on coir pith was also investigated and described well with pseudo second order model. ESR and desorption experiments confirmed that Cr(VI), Cr(V) and Cr(III), exist in coir pith after Cr(VI) adsorption. The desorption data indicated that the percentage of Cr(VI), Cr(V) and Cr(III) in coir pith were 15.63%, 12.89% and 71.48%, respectively.

  10. AM(VI) partitioning studies. FY14 final report

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    Mincher, Bruce J. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-10-01

    The use of higher oxidation states of americium in partitioning from the lanthanides is under continued investigation by the sigma team. This is based on the hypothesis that Am(VI) can be produced and remain stable in irradiated first cycle raffinate solution long enough to perform solvent extraction for separations. The stability of Am(VI) to autoreduction was measured using millimolar americium concentrations in a 1-cm cell with a Cary 6000 UV/Vis spectrophotometer for data acquisition. At millimolar americium concentrations, Am(VI) is stable enough against its own autoreduction for separations purposes. A second major accomplishment during FY14 was the hot test. Americium oxidation and extraction was performed using a centrifugal contactor-based test bed consisting of an extraction stage and two stripping stages. Sixty-three percent americium extraction was obtained in one extraction stage, in agreement with batch contacts. Promising electrochemical oxidation results have also been obtained, using terpyridine ligand derivatized electrodes for binding of Am(III). Approximately 50 % of the Am(III) was oxidized to Am(V) over the course of 1 hour. It is believed that this is the first demonstration of the electrolytic oxidation of americium in a non-complexing solution. Finally, an initial investigation of Am(VI) extraction using diethylhexylbutyramide (DEHBA) was performed.

  11. Integrated Ecogenomics Study for Bioremediation of Cr(VI) at Hanford 100H Area

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    Chakraborty, Romy; Chakraborty, Romy

    2008-08-12

    Hexavalent chromium is a widespread contaminant found in groundwater. In order to stimulate microbially mediated Cr(VI)-reduction, a poly-lactate compound was injected into Cr(VI)-contaminated aquifers at site 100H at Hanford. Investigation of bacterial community composition using high-density DNA microarray analysis of 16S rRNA gene products revealed a stimulation of Pseudomonas, Desulfovibrio and Geobacter species amongst others. Enrichment of these organisms coincided with continued Cr(VI) depletion. Functional gene-array analysis of DNA from monitoring well indicated high abundance of genes involved in nitrate-reduction, sulfate-reduction, iron-reduction, methanogenesis, chromium tolerance/reduction. Clone-library data revealed Psedomonas was the dominant genus in these samples. Based on above results, we conducted lab investigations to study the dominant anaerobic culturable microbial populations present at this site and their role in Cr(VI)-reduction. Enrichments using defined anaerobic media resulted in isolation of an iron-reducing, a sulfate-reducing and a nitrate-reducing isolate among several others. Preliminary 16S rDNA sequence analysis identified the isolates as Geobacter metallireducens, Pseudomonas stutzeri and Desulfovibrio vulgaris species respectively. The Pseudomonas isolate utilized acetate, lactate, glycerol and pyruvate as alternative carbon sources, and reduced Cr(VI). Anaerobic washed cell suspension of strain HLN reduced almost 95?M Cr(VI) within 4 hr. Further, with 100?M Cr(VI) as sole electron-acceptor, cells grew to 4.05 x 107 /ml over 24 h after an initial lag, demonstrating direct enzymatic Cr(VI) reduction coupled to growth. These results demonstrate that Cr(VI)-immobilization at Hanford 100H site could be mediated by direct microbial metabolism in addition to indirect chemical reduction of Cr(VI) by end-products of microbial activity.

  12. A Salmonella Typhimurium-Typhi genomic chimera: a model to study Vi polysaccharide capsule function in vivo.

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    Angela M Jansen

    2011-07-01

    Full Text Available The Vi capsular polysaccharide is a virulence-associated factor expressed by Salmonella enterica serotype Typhi but absent from virtually all other Salmonella serotypes. In order to study this determinant in vivo, we characterised a Vi-positive S. Typhimurium (C5.507 Vi(+, harbouring the Salmonella pathogenicity island (SPI-7, which encodes the Vi locus. S. Typhimurium C5.507 Vi(+ colonised and persisted in mice at similar levels compared to the parent strain, S. Typhimurium C5. However, the innate immune response to infection with C5.507 Vi(+ and SGB1, an isogenic derivative not expressing Vi, differed markedly. Infection with C5.507 Vi(+ resulted in a significant reduction in cellular trafficking of innate immune cells, including PMN and NK cells, compared to SGB1 Vi(- infected animals. C5.507 Vi(+ infection stimulated reduced numbers of TNF-α, MIP-2 and perforin producing cells compared to SGB1 Vi(-. The modulating effect associated with Vi was not observed in MyD88(-/- and was reduced in TLR4(-/- mice. The presence of the Vi capsule also correlated with induction of the anti-inflammatory cytokine IL-10 in vivo, a factor that impacted on chemotaxis and the activation of immune cells in vitro.

  13. A spectroscopic study of uranium(VI) interaction with magnetite

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    El Aamrani, S. [Chemical Engineering Department, Universitat Politecnica de Catalunya (UPC), ETSEIB-UPC H4, Diagonal 647, 08028 Barcelona (Spain); Gimenez, J. [Chemical Engineering Department, Universitat Politecnica de Catalunya (UPC), ETSEIB-UPC H4, Diagonal 647, 08028 Barcelona (Spain)]. E-mail: francisco.javier.gimenez@upc.edu; Rovira, M. [Chemical Engineering Department, Universitat Politecnica de Catalunya (UPC), ETSEIB-UPC H4, Diagonal 647, 08028 Barcelona (Spain); CTM Centre Tecnologic, Avda. Bases de Manresa 1, Manresa (Spain); Seco, F. [CTM Centre Tecnologic, Avda. Bases de Manresa 1, Manresa (Spain); Grive, M. [ENVIROS Spain SL, Passeig de Rubi 29-31, Valldoreix (Spain); Bruno, J. [ENVIROS Spain SL, Passeig de Rubi 29-31, Valldoreix (Spain); Duro, L. [ENVIROS Spain SL, Passeig de Rubi 29-31, Valldoreix (Spain); Pablo, J. de [Chemical Engineering Department, Universitat Politecnica de Catalunya (UPC), ETSEIB-UPC H4, Diagonal 647, 08028 Barcelona (Spain); CTM Centre Tecnologic, Avda. Bases de Manresa 1, Manresa (Spain)

    2007-08-31

    The uranium sorbed onto commercial magnetite has been characterized by using two different spectroscopic techniques such as X-ray photoelectron spectroscopy (XPS), and extended X-ray absorption fine structure (EXAFS). Magnetite samples have been put in contact with uranium(VI) solutions in conditions in which a high uranium uptake is expected. After several days, the magnetite surface has been analysed by XPS and EXAFS. The XPS results obtained are not conclusive regarding the uranium oxidation state in the magnetite surface. On the other hand, the results obtained with the EXAFS technique show that the uranium-magnetite sample spectrum has characteristics from both the UO{sub 2} and schoepite spectra, e.g. a relatively high coordination number of equatorial oxygens and two axial oxygens, respectively. These results would indicate that the uranium sorbed onto magnetite would be a mixture of uranium(IV) and uranium(VI)

  14. Study of reduction of chromium (VI by calcium polysulfide using spectrophotometric method

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    Batukhan Tatykaev

    2013-05-01

    Full Text Available The paper presents  the results of the study on reduction  of  Cr2O72-   to   Cr3 +  by aqueous solution of calcium polysulfide  using spectrophotometric method. Concentrations  of Cr (VI were determined on the basis of the absorption spectrum at the wavelength range 350 - 372 nm. The change of the concentration of Cr (VI during on reduction by calcium polysulfide has been shown.  The influence of pH on the rate of reducing of Cr (VI to Cr (III was considered: the rate of reducing of hexavalent chromium decreases with increasing pH. The data obtained show that recycling Cr (VI in industrial scale potentially effective at  the pH = 5.

  15. Adsorption studies on fruits of Gular (Ficus glomerata): Removal of Cr(VI) from synthetic wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Rifaqat A.K., E-mail: rakrao1@rediffmail.com [Environmental Research Laboratory, Department of Applied Chemistry, Faculty of Engineering and Technology, Aligarh Muslim University, Aligarh 202002, UP (India); Rehman, Fouzia [Environmental Research Laboratory, Department of Applied Chemistry, Faculty of Engineering and Technology, Aligarh Muslim University, Aligarh 202002, UP (India)

    2010-09-15

    The adsorption of Cr(VI) was studied in batch system using fruits of Ficus glomerata as adsorbent. The effect of temperature, pH, initial Cr(VI) concentration and time was investigated. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) was used to investigate surface morphology and active functional groups present on the adsorbent surface. Thermodynamic parameters like free energy change ({Delta}G{sup 0}), enthalpy ({Delta}H{sup 0}) and entropy ({Delta}S{sup 0}) indicate the spontaneous, endothermic and increased randomness nature of Cr(VI) adsorption. Equilibrium data were fitted well with Langmuir isotherm at 50 deg. C. The magnitude of mean free energy indicates chemical nature of adsorption. The breakthrough and exhaustive capacities were found to be 5 and 23.1 mg g{sup -1} respectively. The applicability of the adsorbent has been demonstrated by removing Cr(VI) from electroplating wastewater.

  16. Thermodynamic Insight into the Solvation and Complexation Behavior of U(VI) in Ionic Liquid: Binding of CMPO with U(VI) Studied by Optical Spectroscopy and Calorimetry.

    Science.gov (United States)

    Wu, Qi; Sun, Taoxiang; Meng, Xianghai; Chen, Jing; Xu, Chao

    2017-03-06

    The complexation of U(VI) with octylphenyl-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO, denoted as L) in ionic liquid (IL) C4mimNTf2 was investigated by UV-vis absorption spectrophotometry and isothermal titration calorimetry. Spectro-photometric titration suggests that three successive complexes, UO2Lj(2+) (j = 1-3), formed both in "dry" (water content U(VI) is much stronger, with stability constants of the respective complexes more than 1 order of magnitude higher than that in wet IL. Energetically, the complexation of U(VI) with CMPO in dry IL is mainly driven by negative enthalpies. In contrast, the complexation in wet IL is overwhelmingly driven by highly positive entropies as a result of the release of a large amount of water molecules from the solvation sphere of U(VI). Moreover, comparisons between the fitted absorption spectra of complexes in wet IL and that of extractive samples from solvent extraction have identified the speciation involved in the extraction of U(VI) by CMPO in ionic liquid. The results from this study not only offer a thermodynamic insight into the complexation behavior of U(VI) with CMPO in IL but also provide valuable information for understanding the extraction behavior in the corresponding solvent extraction system.

  17. Removal of Cr(VI from Aqueous Solution Using Modified Pomegranate Peel : Equilibrium and Kinetic Studies

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    Tariq S. Najim

    2009-01-01

    Full Text Available The present investigation deals with the utilization of modified pomegrenate peel (MPGP and formaldehyde modified pomegrenate peel (FMPGP as adsorbents for the removal of chromium Cr(VI from aqueous solution. A series of experiments were conducted in a batch system to evaluate the effect of system variables. The effect of pH, initial Cr(VI concentration, contact time, adsorbent dosage and temperature were considered. The optimal pH values of Cr(VI removal by MPGP and FMPGP were 2.0 and 3.0 respectively. The time required for equilibrium was found to be about 100 minutes. The initial Cr(VI concentration and adsorbent dosage was found to have large effect on the adsorption of Cr(VI. The maximum uptake capacities were 13.01 and 22.28 mg of Cr(VI per gram of MPGP and FMPGP respectively. Adsorption kinetic data were tested using pseudo-first order, pseudo-second order, Elovich and intra-particle diffusion models. Kinetic studies showed that the adsorption followed a pseudo second order reaction due to the high correlation coefficient and the agreement between the experimental and calculated values of qe.The adsorption may follow intraparticle diffusion as well, due to the highest values of rate constants for the surface adsorption and intraparticle diffusion kinetic models, the higher values of rate constants are related to an improved bonding between Cr(VI ions and adsorbent particle.The Dubinin-radushkevich, Freundlich and Tempkin models were the closest fit for the equilibrium data of MPGP and FMPGP.

  18. Biochemical study on the protective role of folic acid in rabbits treated with chromium (VI).

    Science.gov (United States)

    El-Demerdash, Fatma M; Yousef, Mokhtar I; Elaswad, Fathia A M

    2006-01-01

    Deleterious effects of chromium (VI) compounds are diversified affecting almost all the organ systems in a wide variety of animals. Therefore, the present study was carried out to determine the effectiveness of folic acid (FA) in alleviating the toxicity of chromium (VI) on certain biochemical parameters, lipid peroxidation, and enzyme activities of male New Zealand white rabbits. Six rabbits per group were assigned to one of four treatment groups: 0 mg FA and 0 mg Cr(VI)/kg BW (control); 8.3 microg FA/kg BW; 5 mg Cr(VI)/kg BW; 5 mg Cr(VI) plus 8.3 microg FA/kg BW, respectively. Rabbits were orally administered their respective doses every day for 10 weeks. Results obtained showed that Cr(VI) significantly (P content of sulfhydryl groups (SH groups) in liver, testes, brain, kidney, and lung. The activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (AlP), acid phosphatase (AcP), and lactate dehydrogenase (LDH) were significantly decreased in liver and testes due to Cr(VI) administration. Also, AlP and AcP activities were significantly decreased in kidney and lung. The activity of acetylcholinesterase (AChE) was significantly decreased in brain and plasma. Contrariwise, the activities of AST and ALT were significantly increased in plasma, while AlP and AcP decreased. Chromium (VI) treatment caused a significant decrease in plasma total protein (TP) and globulin, and increased total lipids (TL), cholesterol, glucose, urea, creatinine, and bilirubin concentrations. Folic acid alone significantly decreased the levels of free radicals in liver, brain, and kidney, and increased the content of SH-group. The activities of AST, ALT, and LDH in liver; AST, ALT, AlP, AcP, and LDH in testes; AcP in kidney; AlP and AcP in lung, and LDH in brain were significantly increased. Plasma TP and albumin were increased, while urea and creatinine were decreased. The presence of FA with Cr(VI) restored the changes in enzyme activities and

  19. Studies on Cr(VI) removal from aqueous solutions by nanotitania under visible light and dark conditions

    Indian Academy of Sciences (India)

    Madona Lien Paul; Jastin Samuel; Rajdeep Roy; Natarajan Chandrasekaran; Amitava Mukherjee

    2015-04-01

    The current study deals with Cr(VI) removal by nanotitania under fluorescent light and dark conditions. The equilibrium removal capacities, 85.85 and 59.4 mg of Cr(VI)g−1 of nanoparticle were noted for nanotitania interacted under light and dark conditions, respectively, at optimized conditions (pH: 7.0, contact time: 30 min, initial Cr(VI) concentration: 20 mg l−1, nanoparticle dosage: 0.1 g l−1). Under both the conditions, the equilibrium removal data fitted well with the Langmuir isotherm model. The nanotitania followed a second-order kinetics under light condition whereas a pseudo-second-order kinetics was observed under dark condition. The surface characterization of nanotitania was carried out by zeta potential measurement and transmission electron microscope (TEM). Fourier transform infrared (FT-IR) studies carried out under light and dark conditions indicate the interaction of surface functional groups to Cr(VI). Cr(VI) removal study carried out in the Cr(VI)–Cr(III) mixture showed a decrease in Cr(VI) removal capacity with increase in Cr(III) concentration. A 92% regeneration of nanoparticle was observed indicating efficient reusability of the system. The applicability of the nanotitania in Cr(VI) contaminated water was studied by spiking Cr(VI) in natural water matrices like ground water and lake water.

  20. Studies in Annonaceae VI. A leafanatomical survey of genera of Annonaceae in the Neotropics

    NARCIS (Netherlands)

    Setten, van A.K.; Koek-Noorman, J.

    1983-01-01

    SETTEN, A. K. van & KOEK-NOORMAN, J.: Studies in Annonaceae. VI. A leafanatomical survey of genera of Annonaceae in the Neotropics. — Bot. Jahrb. Syst. 108: 17—50. 1986. — ISSN 0006-8152. Within the scope of the multidisciplinary research project on systematics of Annonaceae, a survey of the leafana

  1. Magnetic vinylphenyl boronic acid microparticles for Cr(VI) adsorption: Kinetic, isotherm and thermodynamic studies

    Energy Technology Data Exchange (ETDEWEB)

    Kara, Ali, E-mail: akara@uludag.edu.tr [Uludag University, Faculty of Arts and Science, Department of Chemistry, 16059 Bursa (Turkey); Demirbel, Emel [Uludag University, Faculty of Arts and Science, Department of Chemistry, 16059 Bursa (Turkey); Tekin, Nalan [Kocaeli University, Faculty of Arts and Science, Department of Chemistry, 41380 Kocaeli (Turkey); Osman, Bilgen; Beşirli, Necati [Uludag University, Faculty of Arts and Science, Department of Chemistry, 16059 Bursa (Turkey)

    2015-04-09

    Highlights: • Cr(VI) can oxidize biological molecules and be one of the most harmful substance. • Magnetic seperation techniques are used on different applications in many fields. • Magnetic systems can be used for rapid and selective removal as a magnetic processor. • We investigate properties of both new material and other magnetic adsorbents reported in the literatures on the adsorption of Cr(VI) ions. • No researchments were reported on adsorption of Cr(VI) with magnetic vinylphenyl boronic acid microparticles. - Abstract: Magnetic vinylphenyl boronic acid microparticles, poly(ethylene glycol dimethacrylate(EG)–vinylphenyl boronic acid(VPBA)) [m-poly(EG–VPBA)], produced by suspension polymerization and characterized, was found to be an efficient solid polymer for Cr(VI) adsorption. The m-poly(EG–VPBA) microparticles were prepared by copolymerizing of ethylene glycol dimethylacrylate (EG) with 4-vinyl phenyl boronic acid (VPBA). The m-poly(EG–VPBA) microparticles were characterized by N{sub 2} adsorption/desorption isotherms, electron spin resonance (ESR), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), elemental analysis, scanning electron microscope (SEM) and swelling studies. The m-poly(EG–VPBA) microparticles were used at adsorbent/Cr(VI) ion ratios. The influence of pH, Cr(VI) initial concentration, temperature of the removal process was investigated. The maximum removal of Cr(VI) was observed at pH 2. Langmuir isotherm and Dubinin–Radushkvich isotherm were found to better fit the experiment data rather than Fruendlich isotherm. The kinetics of the adsorption process of Cr(VI) on the m-poly(EG–VPBA) microparticles were investigated using the pseudo first-order, pseudo-second-order, Ritch-second-order and intraparticle diffusion models, results showed that the pseudo-second order equation model provided the best correlation with the experimental results. The thermodynamic

  2. Adsorption studies of chromium (VI) removal from water by lanthanum diethanolamine hybrid material.

    Science.gov (United States)

    Mandal, Sandip; Sahu, Manoj Kumar; Giri, Anil Kumar; Patel, Raj Kishore

    2014-01-01

    In the present research work, lanthanum diethanolamine hybrid material is synthesized by co-precipitation method and used for the removal of Cr(VI) from synthetic dichromate solution and hand pump water sample. The sorption experiments were carried out in batch mode to optimize various influencing parameters such as adsorbent dose, contact time, pH, competitive anions and temperature. The characterization of the material and mechanism of Cr(VI) adsorption on the material was studied by using scanning electron microscope, Fourier transform infrared, X-ray diffraction, Brunauer-Emmett-Teller and thermogravimetric analysis-differential thermal analysis. Adsorption kinetics studies reveal that the adsorption process followed first-order kinetics and intraparticle diffusion model with correlation coefficients (R2) of 0.96 and 0.97, respectively. The adsorption data were best fitted to linearly transformed Langmuir isotherm with correlation coefficient (R2) of 0.997. The maximum removal of Cr(VI) is found to be 99.31% at optimal condition: pH = 5.6 of the solution, adsorbent dose of 8 g L(-1) with initial concentration of 10mgL(-1) of Cr(VI) solution and an equilibrium time of 50 min. The maximum adsorption capacity of the material is 357.1 mg g(-1). Thermodynamic parameters were evaluated to study the effect of temperature on the removal process. The study shows that the adsorption process is feasible and endothermic in nature. The value of E (260.6 kJ mol(-1)) indicates the chemisorption nature of the adsorption process. The material is difficult to be regenerated. The above studies indicate that the hybrid material is capable of removing Cr(VI) from water.

  3. Radiometric and spectrophotometric studies of the behavior of chromium(VI) oxide in concentrated perchloric acid

    Energy Technology Data Exchange (ETDEWEB)

    Pezzin, S.H.; Collins, C.H.; Collins, K.E. [Universidade Estadual de Campinas (Brazil). Inst. de Quimica; Archundia, C. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Ciencias Nucleares

    1997-11-01

    A study of the behavior of {sup 51}CrO{sub 3} in 70% HClO{sub 4} over the temperature range from 20 to 194 C by means of Cr-51 labelling, UV-VIS spectrophotometry and ion exchange chromatography, shows that the solubility of {sup 51}CrO{sub 3} depends on a competition between the dissolution process and the acid reduction of solution phase Cr(VI). These processes occur simultaneously and are dependent on both the temperature and the concentration of Cr(VI), as shown by comparison between radiometric measurements (where total chromium can be accurately determined) and spectrophotometric measurements (where only the Cr(VI) is detectable at the wavelengths studied). These conclusions are confirmed by PbCrO{sub 4} precipitation of {sup 51}Cr(VI), where at 194 C, 97% of the total chromium appears as Pb{sup 51}CrO{sub 4} while at 86 C only 5% does. Cation exchange chromatography of the solution after brief contact of {sup 51}CrO{sub 3} with concentrated HClO{sub 4} at 20 C shows only traces of {sup 51}Cr(VI), most of the radioactivity eluting as {sup 51}Cr(H{sub 2}O){sup 3+}{sub 6}, with smaller amounts of species with +2 and +1 charges. These results imply serious limitations to the spectrophotometric determination of low concentrations of total chromium in alloys or in biological material which use dissolution in 70% HClO{sub 4} as a primary analytical step. (orig.)

  4. Magnetic vinylphenyl boronic acid microparticles for Cr(VI) adsorption: kinetic, isotherm and thermodynamic studies.

    Science.gov (United States)

    Kara, Ali; Demirbel, Emel; Tekin, Nalan; Osman, Bilgen; Beşirli, Necati

    2015-04-09

    Magnetic vinylphenyl boronic acid microparticles, poly(ethylene glycol dimethacrylate(EG)-vinylphenyl boronic acid(VPBA)) [m-poly(EG-VPBA)], produced by suspension polymerization and characterized, was found to be an efficient solid polymer for Cr(VI) adsorption. The m-poly(EG-VPBA) microparticles were prepared by copolymerizing of ethylene glycol dimethylacrylate (EG) with 4-vinyl phenyl boronic acid (VPBA). The m-poly(EG-VPBA) microparticles were characterized by N2 adsorption/desorption isotherms, electron spin resonance (ESR), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), elemental analysis, scanning electron microscope (SEM) and swelling studies. The m-poly(EG-VPBA) microparticles were used at adsorbent/Cr(VI) ion ratios. The influence of pH, Cr(VI) initial concentration, temperature of the removal process was investigated. The maximum removal of Cr(VI) was observed at pH 2. Langmuir isotherm and Dubinin-Radushkvich isotherm were found to better fit the experiment data rather than Fruendlich isotherm. The kinetics of the adsorption process of Cr(VI) on the m-poly(EG-VPBA) microparticles were investigated using the pseudo first-order, pseudo-second-order, Ritch-second-order and intraparticle diffusion models, results showed that the pseudo-second order equation model provided the best correlation with the experimental results. The thermodynamic parameters (free energy change, ΔG(0) enthalpy change, ΔH(0); and entropy change, ΔS(0)) for the adsorption have been evaluated.

  5. EU Collaborative study VI on bacteriological detection of Salmonella spp.

    NARCIS (Netherlands)

    Korver H; Mooijman KA; Nagelkerke NJD; van de Giessen AW; Henken AM; MGB; IMA

    2003-01-01

    Het Communautair Referentie Laboratorium voor Salmonella (CRL-Salmonella, Bilthoven, Nederland) organiseerde in 2002 een zesde bacteriologisch ringonderzoek. Zeventien Nationale Referentie Laboratoria voor Salmonella (NRLs-Salmonella) namen deel aan deze studie. Referentie materialen in combinatie

  6. Wilderness Study Report : Volume VI : Kenai National Moose Range

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — In order to conform to the Wilderness Act of 1964, a study was conducted by the Bureau of Sport Fisheries and Wildlife personnel to ascertain which of the Kenai...

  7. Experimental study on the pathogenesis of epithelial tumors (VI report)

    OpenAIRE

    Fujiki, Hirota; Ichikawa, Koichi; Yamagiwa, Katsusaburo; Maruyama, Koshichiro; Lee, Kunsei; Fukuda,Tamotsu; Kinoshita, Riojun; Kashiwagi, Masatoshi; Ogawa, Juntaro

    2014-01-01

    The concept of cancer and inflammation has a long history. Virchow's irritation theory based on human cancer engendered the essential role of inflammation in carcinogenesis. Drs. Yamagiwa and Ichikawa first published a comprehensive paper entitled “Experimental study on the pathogenesis of epithelial tumors” (I report) in 1915 in German, and went on to publish five more reports (1915–1924) under the same title. They succeeded in demonstrating that inflammation is an important carcinogenic fac...

  8. Chronopotentiometric study of intercalation of layered III-VI semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bakhmatyuk, B.P.; Grigorchak, I.I.; Kaminskii, V.M.; Kovalyuk, Z.D.; Yurtsenyuk, S.P.

    1985-04-01

    The known group of materials open to intercalation (i.e., the incorporation of foreign ions, atoms, or molecules into the space between layers of layered crystals) has recently been enlarged by the layered semiconducting monochalcogenides of indium and gallium. This article is concerned with an electrochemical investigation of their intercalation process. The chronopotentiograms for the reduction and oxidation of electrodes made of the layered monoselenides of indium and gallium in 1 M lithium perchlorate solution in propylene carbonate were examined. The electrodes studied were examined by x-rays before and after intercalation. It is indicated that the intercalation of InSe and GaSe with lithium yields nonstoichiometric phases in the range of 0 is less than x is less than or equal to 1. Using the equilibrium potentials of the intercalated phases and known relations, the free energies of these compounds and of their formation can be determined. The electrochemical intercalation leads to the formation of ternary compounds Li /SUB x/ InSe and Li /SUB x/ GaSe. The free energies of formation of these compounds increase with increasing degree of reduction of the compounds. The intercalation of indium and gallium monoselenide with lithium can be regarded as reversible.

  9. A comparative study of the complexation of uranium(VI) withoxydiacetic acid and its amide derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Linfeng; Tian, Guoxin

    2005-05-01

    There has been significant interest in recent years in the studies of alkyl-substituted amides as extractants for actinide separation because the products of radiolytic and hydrolytic degradation of amides are less detrimental to separation processes than those of organophosphorus compounds traditionally used in actinide separations. Stripping of actinides from the amide-containing organic solvents is relatively easy. In addition, the amide ligands are completely incinerable so that the amount of secondary wastes generated in nuclear waste treatment could be significantly reduced. One group of alkyl-substituted oxa-diamides have been shown to be promising in the separation of actinides from nuclear wastes. For example, tetraoctyl-3-oxa-glutaramide and tetraisobutyl-oxa-glutaramide form actinide complexes that can be effectively extracted from nitric acid solutions. To understand the thermodynamic principles governing the complexation of actinides with oxa-diamides, we have studied the complexation of U(VI) with dimethyl-3-oxa-glutaramic acid (DMOGA) and tetramethyl-3-oxa-glutaramide (TMOGA) in aqueous solutions, in comparison with oxydiacetic acid (ODA) (Figure 1). Previous studies have indicated that the complexation of U(VI) with ODA is strong and entropy-driven. Comparing the results for DMOGA and TMOGA with those for ODA could provide insight into the energetics of amide complexation with U(VI) and the relationship between the thermodynamic properties and the ligand structure.

  10. Kinetic and Mechanistic Study of the Reduction of Chromium(VI by Lactic Acid

    Directory of Open Access Journals (Sweden)

    Jinhuan Shan

    2008-01-01

    Full Text Available The kinetics and mechanism of the reduction of chromium(VI by lactic acid (Lac in aqueous acidic medium was studied with spectrophotometry in a temperature range of 298.15 K~313.15 K. Under the conditions of the pseudo-first order ([Lac]0≫[Cr(VI]0, the observed rate constant (obs increased with the increase in [Lac] and [H+]. There is no salt effect. Based on the experimental results, a probable reaction mechanism of oxidation was proposed. The rate equation derived from the mechanism could explain all the experimental phenomena. Activation parameters along with rate constant of the rate-determining step have been evaluated.

  11. Biosorption of Cr(VI from AqueousSolution Using New Adsorbent: Equilibrium and Thermodynamic Study

    Directory of Open Access Journals (Sweden)

    Israa G. Zainal

    2010-01-01

    Full Text Available Biosorption is one such emerging technology which utilized naturally occurring waste materials to sequester heavy metals from polluted water. In the present study cinnamon was utilized for Cr(VI removal from aqueous solutions.It was found that a time of two hours was sufficient for sorption to attain equilibrium. The optimum pH was 2 for Cr(VI removal. Temprature has little influence on the biosorption process. The Cr(VI removal decreased with increase in temperature. The biosorption data was well fitted to Dubinin - Radushkevich (D-R, Freundlich and Tempkin adsorption isotherm models, although the correlation coefficient of Langmuir model was high but the calculated adsorption capacity did not agree with the experimental. The thermodynamic study reveals that the biosorption process is spontaneous and the spontaneity decreased with temperature increase and the process is exothermic accompanied by highly ordered adsorbate at the solid liquid interface. ΔH° values were negative and lie in the range of physical adsorption.

  12. Spectrophotometric study of neptunium (VI) complexation by nitrate ions; Etude par spectrophotometrie de la complexation du neptunium au degre d'oxydation (VI) par les ions nitrates

    Energy Technology Data Exchange (ETDEWEB)

    Pochon, P. [CEA/VALRHO - site de Marcoule, Dept. de Recherche en Retraitement et en Vitrification (DRRV), 30 - Marcoule (France)]|[Conservatoire National des Arts et Metiers (CNAM), 75 - Paris (France)]|[Centre Regional Associe de Lyon, 69 (France)

    2000-07-01

    Neptunium(VI) complexation by nitrate ions was investigated by visible and near-infrared spectrophotometry, a technique suitable for observing the appearance and evolution of the species in solution. In the absence of reference spectra for Np(VI) nitrate- complexes, mathematical (factor analysis) tools were used to interpret the spectra. These chemo-metric techniques were first tested and validated on a simpler chemical system: Np(VI)complexation by the SiW{sub 11}O{sub 39}{sup 8-} anion. The test media used to investigate Np(VI) nitrate- complexes generally contain nitrate and perchlorate salts at high concentrations (high ionic strength). Media effects arising from the presence of cations, acidity or the perchlorate ion concentration are therefore significant, and no doubt account for the scattered values of the complexation constants published in the literature. The evolution of the neptunium spectra according to the parameters of the reaction medium illustrated these effects and allowed them to be quantified by a global 'perturbation constant'. In order to minimize the spectrum modifications due to media effects, the neptunium nitrate-complexes were studied at constant ionic strength in weak acidic media (2 mol.kg{sup -1}{sub H2O}) in the presence of sodium salts. The bulk formation constants and the spectrum of the NpO{sub 2}(NO{sub 3}){sup +} complex were determined for ionic strength values of 2.2, 4, 6 and 8 mol.kg{sup -1}{sub H2O}. The constants remained on the same order of magnitude regardless of the ionic strength; the thermodynamic constant {beta}{sub 1}{sup 0} determined from them according to specific interaction theory is thus probably of little significance. Conversely, the bulk constants can be corrected for the effects of the perchlorate ions by taking the global 'perturbation constant' into account. (author)

  13. Spectroscopic studies on U(VI)-salicylate complex formation with multiple equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Cha, W.; Cho, H.R.; Jung, E.C.; Park, K.K.; Kim, W.H.; Song, K. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of). Nuclear Chemistry Research Div.

    2012-07-01

    This study investigates multiple equilibria related to the formation of the U(VI)-salicylate complex in a pH range of 3.0-5.5 using UV-Vis absorption and fluorescence measurement techniques. The absorbance changes at the characteristic charge-transfer bands of the complex were monitored, and the results indicated the presence of multiple equilibria and the formation of both 1:1 and 1:2 (U(VI):salicylate) complexes possessing bi-dentate chelate structures. The determined step-wise formation constants (log K{sub 1:1} and log K{sub 1:2}) are as follows: 12.5 {+-} 0.1 and 11.4 {+-} 0.2 for salicylate, 11.2 {+-} 0.1 and 10.1 {+-} 0.2 for 5-sulfosalicylate, and 12.4 {+-} 0.1 and 11.4 {+-} 0.1 for 2,6-dihydroxybenzoate, respectively. The molar absorptivities of the complexes are also provided. Furthermore, time-resolved laser-induced luminescence spectra of U(VI) species demonstrate the presence of both a dynamic and static quenching process upon the addition of a salicylate ligand. Particularly for the luminescent hydroxouranyl species, a strong static quenching effect is observed. The results suggest that both the UO{sub 2}(HSal){sup +} and the U(VI)-Sal chelate complexes serve as ground-state complexes that induce static quenching. The Stern-Volmer parameters were derived based on the measured luminescent intensity and lifetime data. The static quenching constants (log K{sub S}) obtained are 3.3 {+-} 0.1, 4.9 {+-} 0.1, and 4.4 {+-} 0.1 for UO{sub 2}{sup 2+}, (UO{sub 2}){sub 2}(OH){sub 2}{sup 2+} and (UO{sub 2}){sub 3}(OH){sub 5}{sup +}, respectively. (orig.)

  14. Sorption studies on Cr (VI) removal from aqueous solution using cellulose grafted with acrylonitrile monomer.

    Science.gov (United States)

    Hajeeth, T; Sudha, P N; Vijayalakshmi, K; Gomathi, T

    2014-05-01

    Graft copolymerization of acrylonitrile on to cellulosic material derived from sisal fiber can be initiated effectively with ceric ammonium nitrate. The grafting conditions were optimized by changing the concentration of initiator and monomer. The change in crystallinity of the grafted polymeric samples was concluded from the XRD patterns. The prepared cellulose grafted acrylonitrile copolymer was used as an adsorbent to remove Cr (VI) ions from aqueous solutions. The efficiency of the adsorbent was identified from the variation in the percentage of adsorption with contact time, adsorbent dose and pH. From the observed results it was evident that the adsorption of metal ions increases with the increase in contact time and metal ion concentration. An optimum pH was found to be 5.0 for the removal of Cr (VI) from the aqueous solution. The results of the Langmuir, Freundlich, and pseudo first- and second-order studies revealed that the adsorption was found to fit well with Freundlich isotherm and follows pseudo second-order kinetics. From the above results, it was concluded that the cellulose-g-acrylonitrile copolymer was found to be an efficient adsorbent for the removal of Cr (VI) from aqueous waste generated from industries.

  15. Adsorption Studies of Chromium(VI) on Activated Carbon Derived from Mangifera indica (Mango) Seed Shell

    Science.gov (United States)

    Mise, Shashikant; Patil, Trupti Nagendra

    2015-09-01

    The removal of chromium(VI) from synthetic sample by adsorption on activated carbon prepared from Mangifera indica (mango) seed shell have been carried out at room temperature 32 ± 1 °C. The removal of chromium(VI) from synthetic sample by adsorption on two types of activated carbon, physical activation and chemical activation (Calcium chloride and Sodium chloride), Impregnation Ratio's (IR) 0.25, 0.50, 0.75 for optimum time, optimum dosages and variation of pH were studied. It is observed that contact time differs for different carbons i.e. for physically and chemically activated carbons. The contact time decreases for chemically activated carbon compared to the physically activated carbon. It was observed that as dosage increases the adsorption increased along with the increase in impregnation ratio. It was also noted that as I.R. increases the surface area of Mangifera indica shell carbon increased. These dosage data were considered in the construction of isotherms and it was found that adsorption obeys Freundlich Isotherm and does not obey Langmuir Isotherm. The maximum removal of chromium (VI) was obtained in highly acidic medium at a pH of 1.50.

  16. Adsorption isotherm studies of chromium (VI) from aqueous solutions using sol-gel hydrotalcite-like compounds.

    Science.gov (United States)

    Ramos-Ramírez, Esthela; Ortega, Norma L Gutiérrez; Soto, Cesar A Contreras; Gutiérrez, Maria T Olguín

    2009-12-30

    In under-developed countries, industries such as paint and pigment manufacturing, leather tanning, chrome plating and textile processing, usually discharge effluents containing Cr(VI) and Cr(III) into municipal sanitary sewers. It has been reported that Cr(VI) acts as a powerful epithelial irritant and as a human carcinogen. In the present work, hydrotalcite-like compounds with a Mg/Al ratio=2 were synthesized by the sol-gel method. The hydrotalcite-like compounds and their corresponding thermally treated products were characterized by powder X-ray diffraction, infrared spectroscopy and N(2) adsorption. The hydrotalcite-like compounds and the heated solids were used as adsorbents for Cr(VI) in aqueous solutions. Adsorption isotherm studies of Cr(VI) from aqueous solution are described. The adsorbent capacity was determined using the Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherm models. The Cr(VI) adsorption isotherm data fit best to the Langmuir isotherm model. The maximum Cr(VI) uptake by hydrotalcite and the heated solids was determined using the Langmuir equation and was found to range between 26 and 29 mg Cr(VI)/g adsorbent.

  17. ADSORPTION OF CHROMIUM (VI FROM AQUEOUS SOLUTIONS BY DIFFERENT ADMIXTURES – A BATCH EQUILIBRIUM TEST STUDY

    Directory of Open Access Journals (Sweden)

    K. SHIVA PRASHANTH KUMAR

    2014-08-01

    Full Text Available Wide variety of inorganic compounds such as nutrients and trace metals, organic chemicals, radioactive contaminants and pathogens are commonly present as contaminants in the groundwater. Migration of contaminants in soil involves important mechanisms such as molecular diffusion, dispersion under physical processes, adsorption, precipitation and oxidation - reduction under chemical processes and biodegradation under biological process. Cr (VI is a major and dangerous contaminant as per the ground water is concerned. There are numerous research work carried out with concentrated efforts by the researchers towards removal of Cr (VI contaminant from aqueous solutions. There are few studies relevant to Cr (VI removal with respect to utilization of low cost admixtures and also soil type. In the present study, different low cost admixtures like rice husk (RH, shredded tyre (ST and fly ash (FA are used to understand the performance in removal of Cr (VI from aqueous solution and also two different soil types are used along with the admixture. The results are discussed in terms of sorption capacity and performance of individual admixture and combination of admixture with soil in removal of contaminant. The fly ash, rice husk and shredded tyre admixtures are used and the results revealed that the shredded tyre showed higher performance in removal of contaminant concentration. Also, the soil which has more fine particle content (size<0.075 mm IS sieve showed reasonable reduction in concentration of contaminant at the lower levels of contaminant initial concentration. The sorption capacity results of Cr (VI contaminant, treated with various admixtures are further validated with the published work of other investigators. The shredded tyre (ST showed more adsorption capacity, i.e., 3.283 mg/g at pH of 4.8. For other admixtures, adsorption capacity value is varying in the range of 0.07 mg/g to 1.7 mg/g. Only in case of activated alumina and modified saw dust

  18. Column study of chromium(VI) adsorption from electroplating industry by coconut coir pith

    Energy Technology Data Exchange (ETDEWEB)

    Suksabye, Parinda [Joint Graduate School of Energy and Environment, King Mongkut' s University of Technology Thonburi, 91 Pracha-Utit Road, Bangmod, Thungkru, Bangkok 10140 (Thailand); Thiravetyan, Paitip [Division of Biotechnology, School of Bioresources and Technology, King Mongkut' s University of Technology Thonburi, 83 Moo.8 Thakham, Bangkhuntien, Bangkok 10150 (Thailand)], E-mail: paitip.thi@kmutt.ac.th; Nakbanpote, Woranan [Pilot Plant Development and Training Institute, King Mongkut' s University of Technology Thonburi, 83 Moo.8 Thakham, Bangkhuntien, Bangkok 10150 (Thailand)

    2008-12-15

    The removal of Cr(VI) from electroplating wastewater by coir pith was investigated in a fixed-bed column. The experiments were conducted to study the effect of important parameters such as bed depth (40-60 cm) and flow rate (10-30 ml min{sup -1}). At 0.05 C{sub t}/C{sub 0}, the breakthrough volume increased as flow rate decreased or a bed depth increased due to an increase in empty bed contact time (EBCT). The bed depth service time model (BDST) fit well with the experimental data in the initial region of the breakthrough curve, while the simulation of the whole curve using non-linear regression analysis was effective using the Thomas model. The adsorption capacity estimated from the BDST model was reduced with increasing flow rate, which was 16.40 mg cm{sup -3} or 137.91 mg Cr(VI) g{sup -1} coir pith for the flow rates of 10 ml min{sup -1} and 14.05 mg cm{sup -3} or 118.20 mg Cr(VI) g{sup -1} coir pith for the flow rates of 30 ml min{sup -1}. At the highest bed depth (60 cm) and the lowest flow rate (10 ml min{sup -1}), the maximum adsorption reached 201.47 mg Cr(VI) g{sup -1} adsorbent according to the Thomas model. The column was regenerated by eluting chromium using 2 M HNO{sub 3} after adsorption studies. The desorption of Cr(III) in each of three cycles was about 67-70%. The desorption of Cr(III) in each cycle did not reach 100% due to the fact that Cr(V) was present through the reduction of Cr(VI), and was still in coir pith, possibly bound to glucose in the cellulose part of coir pith. Therefore, the Cr(V) complex cannot be desorbed in solution. The evidence of Cr(V) signal was observed in coir pith, {alpha}-cellulose and holocellulose extracted from coir pith using electron spin resonance (ESR)

  19. Column study of chromium(VI) adsorption from electroplating industry by coconut coir pith.

    Science.gov (United States)

    Suksabye, Parinda; Thiravetyan, Paitip; Nakbanpote, Woranan

    2008-12-15

    The removal of Cr(VI) from electroplating wastewater by coir pith was investigated in a fixed-bed column. The experiments were conducted to study the effect of important parameters such as bed depth (40-60cm) and flow rate (10-30ml min(-1)). At 0.05 C(t)/C(0), the breakthrough volume increased as flow rate decreased or a bed depth increased due to an increase in empty bed contact time (EBCT). The bed depth service time model (BDST) fit well with the experimental data in the initial region of the breakthrough curve, while the simulation of the whole curve using non-linear regression analysis was effective using the Thomas model. The adsorption capacity estimated from the BDST model was reduced with increasing flow rate, which was 16.40mg cm(-3) or 137.91mg Cr(VI)g(-1) coir pith for the flow rates of 10ml min(-1) and 14.05mg cm(-3) or 118.20mg Cr(VI)g(-1) coir pith for the flow rates of 30ml min(-1). At the highest bed depth (60cm) and the lowest flow rate (10mlmin(-1)), the maximum adsorption reached 201.47mg Cr(VI)g(-1) adsorbent according to the Thomas model. The column was regenerated by eluting chromium using 2M HNO(3) after adsorption studies. The desorption of Cr(III) in each of three cycles was about 67-70%. The desorption of Cr(III) in each cycle did not reach 100% due to the fact that Cr(V) was present through the reduction of Cr(VI), and was still in coir pith, possibly bound to glucose in the cellulose part of coir pith. Therefore, the Cr(V) complex cannot be desorbed in solution. The evidence of Cr(V) signal was observed in coir pith, alpha-cellulose and holocellulose extracted from coir pith using electron spin resonance (ESR).

  20. Study of coupled-cluster correlations on electromagnetic transitions and hyperfine structure constants of W VI

    CERN Document Server

    Bhowmik, Anal; Roy, Sourav; Majumder, Sonjoy

    2016-01-01

    This work presents precise calculations of important electromagnetic transition amplitudes along with detail of their many-body correlations using relativistic coupled cluster method. Studies of hyperfine interaction constants, useful for plasma diagnostic, with this correlation exhaustive many-body approach are another important area of this work. The calculated oscillator strengths of allowed transitions, amplitudes of forbidden transitions and lifetimes are compared with the other theoretical results wherever available and they show a good agreement. Hyperfine constants of ?different isotopes of W VI, presented in this paper will be helpful to get accurate picture of abundances of this element in different astronomical bodies.

  1. Serum selenium determinants in French adults: the SU.VI.M.AX study.

    Science.gov (United States)

    Arnaud, J; Bertrais, S; Roussel, A M; Arnault, N; Ruffieux, D; Favier, A; Berthelin, S; Estaquio, C; Galan, P; Czernichow, S; Hercberg, S

    2006-02-01

    The objective of the present work was to assess the relationship between serum Se concentrations and environmental determinants (i.e. lifestyle, social activity, geographic region, urban status, education, familial status, physical activity, BMI, tobacco, and food and alcohol consumption). Baseline results from 13 017 subjects (7876 women aged 35-60 and 5141 men aged 45-60) who participated in the SU.VI.M.AX (Supplémentation en Vitamines et Minéraux Antioxydants) study were analysed. Fewer than 2 % of the volunteers had a serum Se status under 0.75 micromol/l, which has been quoted as the cut-off of biological Se sub-deficiency. Women had significantly lower serum Se concentrations than men (1.09 (sd 0.19) micromol/l (n 7423) and 1.14 (sd 0.20) micromol/l (n 4915), P or =30 kg/m2) was associated with decreased serum Se levels. In men, we observed a decrease in serum Se concentrations with increased consumption of vegetables and fruits. In conclusion, though few of the volunteers participating in the SU.VI.M.AX study had Se status in the sub-deficiency range, 83 % of women and 75 % of men had serum concentrations below the value considered optimal for glutathione peroxidase activity. The largest Se associations in both sexes were found with regions, smoking, alcohol, meat and fish consumption. Further studies are needed to understand the difference in Se status between genders.

  2. Crear el lugar (1) Analogías entre la práctica pictórica del cubismo de Picasso y la práctica arquitectónica de Álvaro Siza La Casa Beires, Álvaro Siza; Póvoa do Varzin, Oporto (1973-1976)

    OpenAIRE

    2014-01-01

    [EN] The analysis of Casa Beires is part of the case study methodology with which we aim to put together a cognitive theory relating to Álvaro Siza’s creative process. The central thesis is that Cubism constitutes a rational context in which to break down Siza’s process of conceptualisation and architectural design and recognize it as a system. The drawing of analogies between specific ways in which Picasso produced his Cubist works and Álvaro Siza’s architectural work enables us to explain h...

  3. Reduction of Pu(VI) on Fe surfaces: soft x-ray absorption and resonant inelastic scattering study

    Energy Technology Data Exchange (ETDEWEB)

    Butorin, S.M.; Kvashnina, K.O.; Modin, A.; Nordgren, J. (Dept. of Physics and Materials Science, Uppsala Univ., Uppsala (Sweden)); Guo, J.H. (Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)); Shuh, D.K. (Chemical Science Div., Lawrence Berkeley National Laboratory, Berkeley, CA (United States)); Werme, L. (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden))

    2009-03-15

    Based on analysis of spectral shapes, their dependence on the energy of incident photons and comparison with model calculations and experimental data from the reference sample we can conclude that plutonium from the Pu(VI) solution sorbed on Fe surfaces is likely to be reduced and Pu species sorbed on the Fe foils are mainly in the form of Pu (IV). Current results correlate with what was observed for for Np (V) and U (VI) in our previous studies. Furthermore, combined analysis of present data with model atomic multiplet calculations of RIXS and XAS spectra suggests that significant presence of Pu(III) on the Fe foils is unlikely

  4. Sorption Studies of Chromium(VI and Mercury(II by High Temperature Activated Carbon from Syzygium Jambolanum Nut

    Directory of Open Access Journals (Sweden)

    S. Sophie Beulah

    2010-01-01

    Full Text Available High temperature activated Syzygium Jambolanum nut carbon (HSJC has been effectively used for the removal of Cr(VI and Hg(II from aqueous solution by batch experiments. Effect of pH, carbon dose and equilibration time were determined. Adsorption followed Freundlich and Langmuir isotherms. Kinetic studies indicated that the removal process followed reversible first order equation. Desorption of Cr(VI was done with 1 M NaOH and 10% H2O2 mixture and Hg(II with 2% Na2S in 1% NaOH. The performance of HSJC was compared with a commercial activated carbon (CAC.

  5. Chromium Biosorption from Cr(VI) Aqueous Solutions by Cupressus lusitanica Bark: Kinetics, Equilibrium and Thermodynamic Studies

    Science.gov (United States)

    Netzahuatl-Muñoz, Alma Rosa; Cristiani-Urbina, María del Carmen; Cristiani-Urbina, Eliseo

    2015-01-01

    The present study investigated the kinetics, equilibrium and thermodynamics of chromium (Cr) ion biosorption from Cr(VI) aqueous solutions by Cupressus lusitanica bark (CLB). CLB total Cr biosorption capacity strongly depended on operating variables such as initial Cr(VI) concentration and contact time: as these variables rose, total Cr biosorption capacity increased significantly. Total Cr biosorption rate also increased with rising solution temperature. The pseudo-second-order model described the total Cr biosorption kinetic data best. Langmuir´s model fitted the experimental equilibrium biosorption data of total Cr best and predicted a maximum total Cr biosorption capacity of 305.4 mg g-1. Total Cr biosorption by CLB is an endothermic and non-spontaneous process as indicated by the thermodynamic parameters. Results from the present kinetic, equilibrium and thermodynamic studies suggest that CLB biosorbs Cr ions from Cr(VI) aqueous solutions predominantly by a chemical sorption phenomenon. Low cost, availability, renewable nature, and effective total Cr biosorption make CLB a highly attractive and efficient method to remediate Cr(VI)-contaminated water and wastewater. PMID:26352933

  6. Chromium Biosorption from Cr(VI Aqueous Solutions by Cupressus lusitanica Bark: Kinetics, Equilibrium and Thermodynamic Studies.

    Directory of Open Access Journals (Sweden)

    Alma Rosa Netzahuatl-Muñoz

    Full Text Available The present study investigated the kinetics, equilibrium and thermodynamics of chromium (Cr ion biosorption from Cr(VI aqueous solutions by Cupressus lusitanica bark (CLB. CLB total Cr biosorption capacity strongly depended on operating variables such as initial Cr(VI concentration and contact time: as these variables rose, total Cr biosorption capacity increased significantly. Total Cr biosorption rate also increased with rising solution temperature. The pseudo-second-order model described the total Cr biosorption kinetic data best. Langmuir´s model fitted the experimental equilibrium biosorption data of total Cr best and predicted a maximum total Cr biosorption capacity of 305.4 mg g(-1. Total Cr biosorption by CLB is an endothermic and non-spontaneous process as indicated by the thermodynamic parameters. Results from the present kinetic, equilibrium and thermodynamic studies suggest that CLB biosorbs Cr ions from Cr(VI aqueous solutions predominantly by a chemical sorption phenomenon. Low cost, availability, renewable nature, and effective total Cr biosorption make CLB a highly attractive and efficient method to remediate Cr(VI-contaminated water and wastewater.

  7. Chromium Biosorption from Cr(VI) Aqueous Solutions by Cupressus lusitanica Bark: Kinetics, Equilibrium and Thermodynamic Studies.

    Science.gov (United States)

    Netzahuatl-Muñoz, Alma Rosa; Cristiani-Urbina, María del Carmen; Cristiani-Urbina, Eliseo

    2015-01-01

    The present study investigated the kinetics, equilibrium and thermodynamics of chromium (Cr) ion biosorption from Cr(VI) aqueous solutions by Cupressus lusitanica bark (CLB). CLB total Cr biosorption capacity strongly depended on operating variables such as initial Cr(VI) concentration and contact time: as these variables rose, total Cr biosorption capacity increased significantly. Total Cr biosorption rate also increased with rising solution temperature. The pseudo-second-order model described the total Cr biosorption kinetic data best. Langmuir´s model fitted the experimental equilibrium biosorption data of total Cr best and predicted a maximum total Cr biosorption capacity of 305.4 mg g(-1). Total Cr biosorption by CLB is an endothermic and non-spontaneous process as indicated by the thermodynamic parameters. Results from the present kinetic, equilibrium and thermodynamic studies suggest that CLB biosorbs Cr ions from Cr(VI) aqueous solutions predominantly by a chemical sorption phenomenon. Low cost, availability, renewable nature, and effective total Cr biosorption make CLB a highly attractive and efficient method to remediate Cr(VI)-contaminated water and wastewater.

  8. Oxidative degradation of triazine- and sulfonylurea-based herbicides using Fe(VI): The case study of atrazine and iodosulfuron with kinetics and degradation products

    Science.gov (United States)

    The occurrence of common herbicides (Atrazine, ATZ and Iodosufuron, IDS), in waters presents potential risk to human and ecological health. The oxidative degradation of ATZ and IDS by ferrate(VI) (FeVIO42-, Fe(VI)) is studied at different pH levels where kinetically observed se...

  9. Synthesis, structural investigation and kinetic studies of uranyl(VI) unsymmetrical Schiff base complexes

    Indian Academy of Sciences (India)

    Zahra Asadi; Mozaffar Asadi; Azade Zeinali; Mohammad Ranjkeshshorkaei; Karla Fejfarova; Vaclav Eigner; Michal Dusek; Aliakbar Dehnokhalaji

    2014-11-01

    Uranyl(VI) complexes with unsymmetrical N2O2 Schiff base ligands were synthesized and characterized. Their characterization was performed using UV-Vis, 1H NMR, cyclic voltammetry, single-crystal X-ray crystallography, IR, TG and C.H.N. techniques. X-ray crystallography of the complexes show that beside coordination of the tetradentate Schiff base, one DMF molecule is also coordinated. In order to investigate the effect of the substitutional groups of the Schiff base on the oxidation and reduction potentials, we used the cyclic voltammetry method. Electrochemistry of these complexes showed that the presence of electron releasing groups accelerates oxidation of the complexes. The kinetics of thermal decomposition was studied using thermal gravimetric method (TG) and Coats-Redfern equation. According to Coats-Redfern plots, the kinetics of thermal decomposition of the studied complexes is first-order in all stages. Also the kinetics and mechanism of the exchange reaction of the coordinated solvent with tributylphosphine was carried out in solution, using spectrophotometric method. As a result, the second order rate constants at four temperatures and the activation parameters were calculated showing an associative mechanism for all corresponding complexes. It was concluded that the steric and the electronic properties of the complexes influence the reaction rate significantly.

  10. Complexation of Gluconate with Uranium(VI) in Acidic Solutions: Thermodynamic Study with Structural Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhicheng; Helms, G.; Clark, S. B.; Tian, Guoxin; Zanonato, PierLuigi; Rao, Linfeng

    2009-01-05

    Within the pC{sub H} range of 2.5 to 4.2, gluconate forms three uranyl complexes UO{sub 2}(GH{sub 4}){sup +}, UO{sub 2}(GH{sub 3})(aq), and UO{sub 2}(GH{sub 3})(GH{sub 4}){sup -}, through the following reactions: (1) UO{sub 2}{sup 2+} + GH{sub 4}{sup -} = UO{sub 2}(GH{sub 4}){sup +}, (2) UO{sub 2}{sup 2+} + GH{sub 4}{sup -} = UO{sub 2}(GH{sub 3})(aq) + H{sup +}, and (3) UO{sub 2}{sup 2+} + 2GH{sub 4}{sup -} = UO{sub 2}(GH{sub 3})(GH{sub 4}){sup -} + H{sup +}. Complexes were inferred from potentiometric, calorimetric, NMR, and EXAFS studies. Correspondingly, the stability constants and enthalpies were determined to be log {Beta}{sub 1} = 2.2 {+-} 0.3 and {Delta}H{sub 1} = 7.5 {+-} 1.3 kJ mol{sup -1} for reaction (1), log {Beta}{sub 2} = -(0.38 {+-} 0.05) and {Delta}H{sub 2} = 15.4 {+-} 0.3 kJ mol{sup -1} for reaction (2), and log {Beta}{sub 3} = 1.3 {+-} 0.2 and {Delta}H{sub 3} = 14.6 {+-} 0.3 kJ mol{sup -1} for reaction (3), at I = 1.0 M NaClO{sub 4} and t = 25 C. The UO{sub 2}(GH{sub 4}){sup +} complex forms through the bidentate carboxylate binding to U(VI). In the UO{sub 2}(GH{sub 3})(aq) complex, hydroxyl-deprotonated gluconate (GH{sub 3}{sup 2-}) coordinates to U(VI) through the five-membered ring chelation. For the UO{sub 2}(GH{sub 3})(GH{sub 4}){sup -} complex, multiple coordination modes are suggested. These results are discussed in the context of trivalent and pentavalent actinide complexation by gluconate.

  11. Quantum chemistry study of uranium(VI), neptunium(V), and plutonium(IV,VI) complexes with preorganized tetradentate phenanthrolineamide ligands.

    Science.gov (United States)

    Xiao, Cheng-Liang; Wu, Qun-Yan; Wang, Cong-Zhi; Zhao, Yu-Liang; Chai, Zhi-Fang; Shi, Wei-Qun

    2014-10-20

    The preorganized tetradentate 2,9-diamido-1,10-phenanthroline ligand with hard-soft donors combined in the same molecule has been found to possess high selectivity toward actinides in an acidic aqueous solution. In this work, density functional theory (DFT) coupled with the quasi-relativistic small-core pseudopotential method was used to investigate the structures, bonding nature, and thermodynamic behavior of uranium(VI), neptunium(V), and plutonium(IV,VI) with phenanthrolineamides. Theoretical optimization shows that Et-Tol-DAPhen and Et-Et-DAPhen ligands are both coordinated with actinides in a tetradentate chelating mode through two N donors of the phenanthroline moiety and two O donors of the amide moieties. It is found that [AnO2L(NO3)](n+) (An = U(VI), Np(V), Pu(VI); n = 0, 1) and PuL(NO3)4 are the main 1:1 complexes. With respect to 1:2 complexes, the reaction [Pu(H2O)9](4+)(aq) + 2L(org) + 2NO3(-)(aq) → [PuL2(NO3)2](2+)(org) + 9H2O(aq) might be another probable extraction mechanism for Pu(IV). From the viewpoint of energy, the phenanthrolineamides extract actinides in the order of Pu(IV) > U(VI) > Pu(VI) > Np(V), which agrees well with the experimental results. Additionally, all of the thermodynamic reactions are more energetically favorable for the Et-Tol-DAPhen ligand than the Et-Et-DAPhen ligand, indicating that substitution of one ethyl group with one tolyl group can enhance the complexation abilities toward actinide cations (anomalous aryl strengthening).

  12. Hypoxic ventilatory sensitivity in men is not reduced by prolonged hyperoxia (Predictive Studies V and VI)

    Science.gov (United States)

    Gelfand, R.; Lambertsen, C. J.; Clark, J. M.; Hopkin, E.

    1998-01-01

    Potential adverse effects on the O2-sensing function of the carotid body when its cells are exposed to toxic O2 pressures were assessed during investigations of human organ tolerance to prolonged continuous and intermittent hyperoxia (Predictive Studies V and VI). Isocapnic hypoxic ventilatory responses (HVR) were determined at 1.0 ATA before and after severe hyperoxic exposures: 1) continuous O2 breathing at 1.5, 2.0, and 2.5 ATA for 17.7, 9.0, and 5.7 h and 2) intermittent O2 breathing at 2.0 ATA (30 min O2-30 min normoxia) for 14.3 O2 h within 30-h total time. Postexposure curvature of HVR hyperbolas was not reduced compared with preexposure controls. The hyperbolas were temporarily elevated to higher ventilations than controls due to increments in respiratory frequency that were proportional to O2 exposure time, not O2 pressure. In humans, prolonged hyperoxia does not attenuate the hypoxia-sensing function of the peripheral chemoreceptors, even after exposures that approach limits of human pulmonary and central nervous system O2 tolerance. Current applications of hyperoxia in hyperbaric O2 therapy and in subsea- and aerospace-related operations are guided by and are well within these exposure limits.

  13. TRLFS Studies on luminescence enhancement of U(VI) using oxidants for quencher species in samples

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Wansik; Jung, Euo Chang; Cho, Hye Ryun [Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-10-15

    The pulse laser-based method detects photo luminescent emission of U(VI) so that it is highly sensitive for non-isotopic al determination of total uranium concentration. Thus, this method has been used for detection of trace quantity of uranium in the environmental, geological, and bioassay samples. One of widely-used pulse laser-based methods is kinetic phosphorescence analysis (KPA), of which instrument is commercially available. The intensity and lifetime of characteristic phosphorescence at 515-520 nm of hexavalent uranium are measured with an excitation wavelength of 425 nm. Particularly in KPA the use of phosphate-based luminescence enhancing agent (LEA) leading to the formation of uranyl-phosphate complexes extends the luminescence (LM) lifetime of uranium (> {approx} 200 {mu}s) and subsequently the overall luminescence intensity. In KPA, however, an extensive sample pretreatment procedure is required to reduce the luminescence quenching effects of ions and molecules present in samples. During such procedures the uranium species in low oxidation states are also oxidized to hexavalent uranium so that the measurement of the total uranium concentration can be achieved. In general, a series of high temperature dry and wet ashing procedures is implemented prior to the addition of LEA to decompose the interfering substances. The aim of this study is to examine the characteristics of the interfering species exhibiting significant quenching effects and to develop a way of minimizing the time required for the sample pretreatment step particularly for certain oxidizable quencher species. In fact, in a previous study we reported that significant LM quenching effects are observed from those possessing chemical reduction capability such as Fe(II) and cysteine. Under such sample conditions it is shown that the conventional KPA is not applicable due to the short lifetime (< {approx} 1 {mu}s), therefore a time-resolved laser-induced fluorescence spectroscopy (TRLFS) capable

  14. Vi serology in screening of typhoid carriers: improved specificity by detection of Vi antibodies by counterimmunoelectrophoresis.

    OpenAIRE

    Chau, P. Y.; Tsang, R S

    1982-01-01

    A purified soluble Vi antigen was used in counterimmunoelectrophoresis (CIE), passive haemagglutination (HA) and solid phase radio-immunoassay (SPRIA) for detection of serum Vi antibody. Serum Vi antibody was detected in 13 of 14 chronic typhoid carriers by both CIE and HA. SPRIA studies showed that Vi antibodies in sera of these carriers were mainly of the IgG class. Successful treatment with amoxycillin in one carrier, who initially showed a positive Vi test, resulted in a reversion in 6 mo...

  15. Studies on biosorption of Cr(VI) on a green resin: dry cow dung powder and tracer technique

    Energy Technology Data Exchange (ETDEWEB)

    Barot, N.S.; Bagla, H.K. [Kishinchand Chellaram College, Mumbai (India). Nuclear and Radiochemistry Dept.

    2012-07-01

    The present investigation entails the application of dry cow dung powder (DCP) as an indigenous, inexpensive and eco-friendly material for the removal of Cr(VI) from aqueous medium. Batch biosorption experiments were conducted employing {sup 51}Cr(VI) as a tracer and the effect of various process parameters such as optimum pH, temperature, amount of resin, time of equilibration, agitation speed, concentration of metal ions and interfering effect of different salts etc. were studied. The kinetic studies were carried out employing various models but the best fitting was given by Lagergren Pseudo-second order model with high correlation coefficient R{sup 2} value of 0.997 and adsorption capacity of 10.20 mg/g. The thermodynamic parameters for biosorption were evaluated as {Delta}G = -2.837 kJ/mol, {Delta}H = -4.757 kJ/mol and {Delta}S = 16.64 J/mol K, which indicated spontaneous and exothermic process with high affinity of DCP for Cr(VI). Many naturally available materials are used for the biosorption of heavy metal pollutants, where most of them are physically or chemically modified. In this research work, DCP has been utilized without any pre or post chemical treatment. Thus it manifests the principle of green chemistry and proves to be an eco-friendly resin. (orig.)

  16. Controversial issues confronting the BEIR III committee: implications for radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    Fabrikant, J.I.

    1981-05-01

    This paper reviews the state-of-the-art for conducting risk assessment studies, especially known and unknown factors relative to radioinduced cancer or other diseases, sources of scientific and epidemiological data, dose-response models used, and uncertainties which limit precision of estimation of excess radiation risks. These are related to decision making for radiation protection policy. (PSB)

  17. Mucopolysaccharidosis VI

    Directory of Open Access Journals (Sweden)

    Harmatz Paul

    2010-04-01

    Full Text Available Abstract Mucopolysaccharidosis VI (MPS VI is a lysosomal storage disease with progressive multisystem involvement, associated with a deficiency of arylsulfatase B leading to the accumulation of dermatan sulfate. Birth prevalence is between 1 in 43,261 and 1 in 1,505,160 live births. The disorder shows a wide spectrum of symptoms from slowly to rapidly progressing forms. The characteristic skeletal dysplasia includes short stature, dysostosis multiplex and degenerative joint disease. Rapidly progressing forms may have onset from birth, elevated urinary glycosaminoglycans (generally >100 μg/mg creatinine, severe dysostosis multiplex, short stature, and death before the 2nd or 3rd decades. A more slowly progressing form has been described as having later onset, mildly elevated glycosaminoglycans (generally ARSB gene, located in chromosome 5 (5q13-5q14. Over 130 ARSB mutations have been reported, causing absent or reduced arylsulfatase B (N-acetylgalactosamine 4-sulfatase activity and interrupted dermatan sulfate and chondroitin sulfate degradation. Diagnosis generally requires evidence of clinical phenotype, arylsulfatase B enzyme activity ®, clinical management was limited to supportive care and hematopoietic stem cell transplantation. Galsulfase is now widely available and is a specific therapy providing improved endurance with an acceptable safety profile. Prognosis is variable depending on the age of onset, rate of disease progression, age at initiation of ERT and on the quality of the medical care provided.

  18. 25 years after Vi typhoid vaccine efficacy study, typhoid affects significant number of population in Nepal.

    Directory of Open Access Journals (Sweden)

    Deepak Bajracharya

    Full Text Available Salmonella Typhi, first isolated in 1884, results in infection of the intestines and can end in death and disability. Due to serious adverse events post vaccination, whole cell killed vaccines have been replaced with new generation vaccines. The efficacy of Vi polysaccharide (ViPS vaccine, a new generation, single-dose intramuscular typhoid vaccine was assessed in Nepal in 1987. However, despite the availability of ViPS vaccine for more than 25 years, Nepal has one of the highest incidence of typhoid fever. Therefore we collected information from hospitals in the Kathmandu Valley from over the past five years. There were 9901 enteric fever cases between January 2008 and July 2012. 1,881 of these were confirmed typhoid cases from five hospitals in the Kathmandu district. Approximately 70% of the cases involved children under 15 years old. 1281 cases were confirmed as S. Paratyphi. Vaccines should be prioritized for control of typhoid in conjunction with improved water and sanitation conditions in Nepal and in endemic countries of Asia and Africa.

  19. 25 years after Vi typhoid vaccine efficacy study, typhoid affects significant number of population in Nepal.

    Science.gov (United States)

    Bajracharya, Deepak; Khan, M Imran; Pach, Alfred; Shrestha, Parisha; Joshi, Nilesh; Upreti, Shyam R; Wierzba, Thomas; Puri, Mahesh; Sahastrabuddhe, Sushant; Ochiai, R Leon

    2014-01-01

    Salmonella Typhi, first isolated in 1884, results in infection of the intestines and can end in death and disability. Due to serious adverse events post vaccination, whole cell killed vaccines have been replaced with new generation vaccines. The efficacy of Vi polysaccharide (ViPS) vaccine, a new generation, single-dose intramuscular typhoid vaccine was assessed in Nepal in 1987. However, despite the availability of ViPS vaccine for more than 25 years, Nepal has one of the highest incidence of typhoid fever. Therefore we collected information from hospitals in the Kathmandu Valley from over the past five years. There were 9901 enteric fever cases between January 2008 and July 2012. 1,881 of these were confirmed typhoid cases from five hospitals in the Kathmandu district. Approximately 70% of the cases involved children under 15 years old. 1281 cases were confirmed as S. Paratyphi. Vaccines should be prioritized for control of typhoid in conjunction with improved water and sanitation conditions in Nepal and in endemic countries of Asia and Africa.

  20. NUEVO ESTUDIO DEL TEMPLO VI (TEMPLO DE LAS INSCRIPCIONES DE TIKAL, GUATEMALA (New Study of the Tikal Temple VI (Temple of the Inscriptions, Guatemala

    Directory of Open Access Journals (Sweden)

    Dmitri Beliaev

    2016-03-01

    Full Text Available El presente trabajo analiza los datos sobre la cronología del Templo VI (Templo de las Inscripciones de Tikal. Durante el trabajo de la segunda fase del proyecto «Atlas Epigráfico de Petén» (abril-mayo de 2014, fue documentada la inscripción en la crestería del templo, el texto jeroglífico del Clásico Tardío más grande del Petén y uno de los más extensos de todas las Tierras Bajas mayas. La secuencia de la construcción del relieve y estuco modelado observada en la crestería, junto con los datos epigráficos, muestra que el Templo VI fue construido en dos fases. La primera incluyó la edificación de la pirámide basal, el santuario y el relieve en la fachada este de la crestería, dedicados por el rey Yihk’in Chan K’awil en 735. En la segunda fase, fechada hacia 766, el templo fue ampliado y adornado con los relieves de las fachadas norte y sur. ENGLISH: In this paper, data related to the chronology of Temple VI (The Temple of the Inscriptions at Tikal is analyzed. During the second season of fieldwork on the “Atlas Epigráfico de Petén” project (April-May 2014, we documented the inscription on the roof comb of the temple, which is the largest hieroglyphic text from the Late Classic at Petén and one of the largest in the Maya Lowlands. The construction sequence of the relief and sculpted stucco observed on the roof comb, combined with epigraphic data, demonstrates that Temple VI was constructed in two phases. The first included the raising of the basal pyramid, the upper sanctuary, and the relief on the eastern façade of the roof comb, dedicated by the king Yihk’in Chan K’awil in 735 A.D. During the second phase, dated to around 766 A.D., the temple was enlarged and adorned with the reliefs on the north and south facades.

  1. Experimental Study of U(VI) Release Kinetics from Aquifer Sediments from a Former Uranium Mill Tailings Site (Rifle, Colorado, USA)

    Science.gov (United States)

    Hyun, S.; Campbell, K. M.; Hayes, K. F.; Davis, J. A.

    2007-12-01

    Uranium(VI) release kinetics from aquifer sediments from a former uranium mill tailings site in Rifle, Colorado was studied to understand uranium distribution within the sediments. The sediments were sampled at depths of 3.5-3.8 m in December 2004. The samples were air-dried, sieved, and the uranium content in the sediments, determined by gamma-radiometry, was 4.1 μg/g sediment. The labile fraction of U(VI) in the sediments was determined using carbonate/bicarbonate extractions, which should cause complete desorption of U(VI) in the absence of mass transfer limitations. Carbonate/bicarbonate extraction of the sediments showed very slow release kinetics, with only 12 % of the labile U(VI) in the sediments being released during the first 96 hours of extraction. This is much less than found in a previous study at a different mill tailings site (Naturita, Colorado), in which more than 80 % of labile U(VI) was released during the same period of extraction. Up to two months of carbonate/bicarbonate extraction released 1 μg U(VI) per gram of Rifle sediment, which is 25 % of the total U in the sediment. Extraction with an artificial groundwater prepared to simulate the field groundwater chemistry showed 0.26 μg U/g sediment was released during the initial 94 hours of extraction, with a gradual increase of released U(VI) with time, while other major and minor elements (except Si) rapidly reached steady-state concentrations during the first few hours of reaction. Two hypotheses are under consideration to explain the slow U(VI) release kinetics: 1) colloidal clay fraction particles cementing larger grains of the sediments are creating nanoscale interparticle pores that act as a diffusion barrier to U(VI) desorption, and 2) a U(IV) solid phase exists whose oxidation and dissolution control the U(VI) release rate. To test the hypotheses, oxidation and extraction of the sediments have been conducted using oxidants such as hydrogen peroxide. The results of this study are

  2. A plan for study of hexavalent chromium, CR(VI) in groundwater near a mapped plume, Hinkley, California, 2016

    Science.gov (United States)

    Izbicki, John A.; Groover, Krishangi

    2016-01-22

    The Pacific Gas and Electric Company (PG&E) Hinkley compressor station, in the Mojave Desert 80 miles northeast of Los Angeles, is used to compress natural gas as it is transported through a pipeline from Texas to California. Between 1952 and 1964, cooling water used at the compressor station was treated with a compound containing chromium to prevent corrosion. After cooling, the wastewater was discharged to unlined ponds, resulting in contamination of soil and groundwater in the underlying alluvial aquifer (Lahontan Regional Water Quality Control Board, 2013). Since 1964, cooling-water management practices have been used that do not contribute chromium to groundwater.In 2007, a PG&E study of the natural background concentrations of hexavalent chromium, Cr(VI), in groundwater estimated average concentrations in the Hinkley area to be 1.2 micrograms per liter (μg/L), with a 95-percent upper-confidence limit of 3.1 μg/L (CH2M-Hill, 2007). The 3.1 μg/L upper-confidence limit was adopted by the Lahontan Regional Water Quality Control Board (RWQCB) as the maximum background concentration used to map the plume extent. In response to criticism of the study’s methodology, and an increase in the mapped extent of the plume between 2008 and 2011, the Lahontan RWQCB (Lahontan Regional Water Quality Control Board, 2012) agreed that the 2007 PG&E background-concentration study be updated.The purpose of the updated background study is to evaluate the presence of natural and man-made Cr(VI) near Hinkley, Calif. The study also is to estimate natural background Cr(VI) concentrations in the aquifer upgradient and downgradient from the mapped Cr(VI) contamination plume, as well as in the plume and near its margins. The study was developed by the U.S. Geological Survey (USGS) in collaboration with a technical working group (TWG) composed of community members, the Independent Review Panel (IRP) Manager (Project Navigator, Ltd.), the Lahontan RWQCB, PG&E, and consultants for PG&E.&E.

  3. Determination of uranium(VI) sorbed species in calcium silicate hydrate phases: a laser-induced luminescence spectroscopy and batch sorption study.

    Science.gov (United States)

    Tits, Jan; Geipel, Gerhard; Macé, Nathalie; Eilzer, Manuela; Wieland, Erich

    2011-07-01

    Batch sorption experiments and time-resolved luminescence spectroscopy investigations were carried out to study the U(VI) speciation in calcium silicate hydrates for varying chemical conditions representing both fresh and altered cementitious environments. U(VI) uptake was found to be fast and sorption distribution ratios (R(d) values) were very high indicating strong uptake by the C-S-H phases. In addition a strong dependence of pH and solid composition (Ca:Si mol ratio) was observed. U(VI) luminescence spectroscopy investigations showed that the U(VI) solid speciation continuously changed over a period up to 6 months in contrast to the fast sorption kinetics observed in the batch sorption studies. Decay profile analysis combined with factor analysis of series of spectra of U(VI)-C-S-H suspensions, recorded with increasing delay times, revealed the presence of four luminescent U(VI) species in C-S-H suspensions, in agreement with the batch sorption data. Along with the aqueous UO(2)(OH)(4)(2-) species and a Ca-uranate precipitate, two different sorbed species were identified which are either bound to silanol groups on the surface or incorporated in the interlayer of the C-S-H structure.

  4. Ultrastructures of Reilly bodies (metachromatic granules) in the Maroteaux-Lamy syndrome (mucopolysaccharidosis VI). A histochemical study.

    Science.gov (United States)

    Levy, L A; Lewis, J C; Sumner, T E

    1980-03-01

    The leukocytes from an 8-year-old white girl having features of the Maroteaux-Lamy syndrome (mucopolysaccharidosis VI) contained large granular inclusions (Reilly granules). Light and electron microscopy showed that these granules had characteristics of those seen in several other types of mucopolysaccharidoses, including Morquio's syndrome, which are of a different structure than those of other types of mucopolysaccharidosis. Similar granules were seen in the platelets, a finding which, so far as we know, has never been reported before. The granules contained an acid mucosubstance demonstrated by cytochemical studies.

  5. Kinetics and equilibrium studies of adsorption of chromium(VI) ion from industrial wastewater using Chrysophyllum albidum (Sapotaceae) seed shells.

    Science.gov (United States)

    Amuda, O S; Adelowo, F E; Ologunde, M O

    2009-02-01

    A new biosorbent has been prepared by coating Chrysophyllum albidum (Sapotaceae) seed shells with chitosan and/or oxidizing agents such as sulfuric acid. This study investigated the technical feasibility of activated and modified activated C. albidum seed shells carbons for the adsorption of chromium(VI) from aqueous solution. The sorption process with respect to its equilibria and kinetics as well as the effects of pH, contact time, adsorbent mass, adsorbate concentration and particle size on adsorption was also studied. The most effective pH range was found to be between 4.5 and 5 for the sorption of the metal ion. The pseudo-first-order rate equation by Lagergren and pseudo-second-order rate equation were tested on the kinetic data, the adsorption process followed pseudo-second-order rate kinetics, also, isotherm data was analyzed for possible agreement with the Langmuir and Freundlich adsorption isotherms, the Freundlich and Langmuir models for dynamics of metal ion uptake proposed in this work fitted the experimental data reasonably well. However, equilibrium sorption data were better represented by Langmuir model than Freundlich. The adsorption capacity calculated from Langmuir isotherm was 84.31, 76.23 and 59.63mgCr(VI)/g at initial pH of 3.0 at 30 degrees C for the particle size of 1.00-1.25mm with the use of 12.5, 16.5 and 2.1g/L of CACASC, CCASC and ACASC adsorbent mass, respectively. This readily available adsorbent is efficient in the uptake of Cr(VI) ion in aqueous solution, thus, it could be an excellent alternative for the removal of heavy metals and organic matter from water and wastewater.

  6. Utilization of waste product (tamarind seeds) for the removal of Cr(VI) from aqueous solutions: equilibrium, kinetics, and regeneration studies.

    Science.gov (United States)

    Gupta, Suresh; Babu, B V

    2009-07-01

    In the present study, an adsorbent was prepared from tamarind seeds and used after activation for the removal of Cr(VI) from aqueous solutions. The tamarind seeds were activated by treating them with concentrated sulfuric acid (98% w/w) at a temperature of 150 degrees C. The adsorption of Cr(VI) was found to be maximum at low values of initial pH in the range of 1-3. The adsorption process of Cr(VI) was tested with Langmuir, Freundlich, Redlich-Peterson, Koble-Corrigan, Tempkin, Dubinin-Radushkevich and Generalized isotherm models. Application of the Langmuir isotherm to the system yielded a maximum adsorption capacity of 29.7 mg/g at an equilibrium pH value ranging from 1.12 to 1.46. The adsorption process followed second-order kinetics and the corresponding rate constants obtained were 2.605 x 10(-3), 0.818 x 10(-3), 0.557 x 10(-3) and 0.811 x 10(-3) g/mg min(-1) for 50, 200, 300 and 400 mg/L of initial Cr(VI) concentration, respectively. The regenerated activated tamarind seeds showed more than 95% Cr(VI) removal of that obtained using the fresh activated tamarind seeds. A feasible solution is proposed for the disposal of the contaminants (acid and base solutions) containing high concentrations of Cr(VI) obtained during the regeneration (desorption) process.

  7. Experimental study of the U(VI)-Humate-H{sub 2}O system with respect to the pH (4-12) at T = 25 deg C, 0.1MPa; Etude expeimentale du systeme U (VI) - Humate - H{sub 2}O en fonction du pH (4-12) a T = 25 deg C, 0.1MPa

    Energy Technology Data Exchange (ETDEWEB)

    Pourtier, E.; Deng, C. [UHP Nancy1, UMR7566G2R, 54 - Vandoeuvre-les-Nancy (France); Nguyen-Trung, C. [CREGU, 54 - Vandoeuvre les Nancy (France); Perdicakis, M.; Bordg, D. [LCPME, 54 - Villers-les-Nancy (France)

    2009-07-01

    Within the frame of the investigation of interactions between uranium (VI) and hydrosoluble organic compounds for the prediction of the evolution of this ion in natural aquatic systems, and in order to obtain some missing data, the authors report a systematic experimental investigation of the interactions between U(VI) and humate in aqueous media. This study comprises a synthesis of humic acid, detection, identification and characterization of U(VI)-humate compounds with respect to different parameters (pH, U(VI) content and humate chemical composition), and the determination of conditional formation constants with respect to the pH. Significant results are commented

  8. NUEVO ESTUDIO DEL TEMPLO VI (TEMPLO DE LAS INSCRIPCIONES) DE TIKAL, GUATEMALA (New Study of the Tikal Temple VI (Temple of the Inscriptions), Guatemala)

    OpenAIRE

    Dmitri Beliaev; Mónica de León Antillón; Philipp Galeev; Sergei Vepretskii

    2016-01-01

    El presente trabajo analiza los datos sobre la cronología del Templo VI (Templo de las Inscripciones) de Tikal. Durante el trabajo de la segunda fase del proyecto «Atlas Epigráfico de Petén» (abril-mayo de 2014), fue documentada la inscripción en la crestería del templo, el texto jeroglífico del Clásico Tardío más grande del Petén y uno de los más extensos de todas las Tierras Bajas mayas. La secuencia de la construcción del relieve y estuco modelado observada en la crestería, junto con los d...

  9. Electron energy loss spectroscopy techniques for the study of microbial chromium(VI) reduction

    Science.gov (United States)

    Daulton, Tyrone L.; Little, Brenda J.; Lowe, Kristine; Jones-Meehan, Joanne

    2002-01-01

    Electron energy loss spectroscopy (EELS) techniques were used to determine oxidation state, at high spatial resolution, of chromium associated with the metal-reducing bacteria, Shewanella oneidensis, in anaerobic cultures containing Cr(VI)O4(2-). These techniques were applied to fixed cells examined in thin section by conventional transmission electron microscopy (TEM) as well as unfixed, hydrated bacteria examined by environmental cell (EC)-TEM. Two distinct populations of bacteria were observed by TEM: bacteria exhibiting low image contrast and bacteria exhibiting high contrast in their cell membrane (or boundary) structure which was often encrusted with high-contrast precipitates. Measurements by EELS demonstrated that cell boundaries became saturated with low concentrations of Cr and the precipitates encrusting bacterial cells contained a reduced form of Cr in oxidation state + 3 or lower.

  10. Background Study of Intact Stability Standards for Dynamically Supported Craft. Volume I - VI. Categorized Bibliographies.

    Science.gov (United States)

    1979-04-01

    Important to Program to Program I - ,.upporting Material REFERENCE EVAI.UATION AND SUBJEI ICT INDEX U) C01Q 4) H a Hal UL0 U .J [,1 -i4 L) I-4 I.,.-4 H...1111 iit eIIIi * I.C.eil vu ’ ict I tes 1 1, I% . l / 1 . ASIJ I 10-tI10 it) 1. Retiumuk-.i : yott Kimm aua iv; t . I .e Serf I o I I Lilt ACVS. VI "A...o -Ist I c . ofI l’tlztI o o i1 MAY o I Sbt i ps" , liv 1ll r - elt . SNAREVtA I AA , May 196 . Set’ BOLIt N(u. n (18. tfiOt*RN~FR "Flid-DlYth,1i~t c

  11. Reduction of the U(VI) ion. A fast conductimetry study

    Energy Technology Data Exchange (ETDEWEB)

    Broszkiewicz, R.K. (Institute of Nuclear Chemistry and Technology, Warsaw (Poland)); Vojnovic, B.; Michael, B.D. (Mount Vernon Hospital, Northwood (UK). Gray Lab.)

    1991-01-01

    The reduction of U(VI) by e{sub aq}{sup -} was followed by means of fast conductimetry in acid and conductimetry and spectrophotometry in alkaline solutions. In alkaline solutions, the biomolecular rate constant of reaction between UO{sub 4}{sup 2-} and e{sub aq}{sup -} was determined. Analytical methods applied in this work were too fast to follow the slow disproportionation of produced U(V)-ion, but it has been observed that in alkaline solutions it probably goes via a dimeric ion (U(V)){sub 2}, which protonates with a rate {kappa}{sub 7} = 1.30 x 10{sup 5}s{sup -1}. (author).

  12. Synchrotron Spectroscopic Studies of the Reaction of Cleaved Pyrite ( {FeS2}) Surfaces with Cr(VI) Solutions

    Science.gov (United States)

    Doyle, C. S.; Kendelewicz, T.; Bostick, B. C.; Brown, G. E.

    2002-12-01

    Pyrite is one of the most common sulfide ores, and the separation of valuable sulfide minerals from it has been an area of considerable interest for a long time. This extraction has led to a large quantity of pyrite waste, typically remaining in mine tailings piles which can interact with oxygen and surface water. The oxidation of pyrite under these conditions leads to the commonly known environmental problem of acid mine drainage, with acidification of surface waters, and the release of potentially toxic metals remaining within the pyrite matrix. A microscopic understanding of this oxidation process is extremely important and has been the aim of a number of studies. We apply the methods of synchrotron based surface science to this problem, utilizing surface sensitive photoemission and X-ray absorption spectroscopy to study the surface species present on the pyrite surface at the initial stages of oxidation. We have reacted pyrite surfaces with solutions containing chromate. Chromium exists in solution in two principal valence states, trivalent Cr(III) and hexavalent Cr(VI). Hexavalent chromium is itself considered an environmental problem due to its high toxicity and solubility, and thus mobility, whilst trivalent chromium is much less toxic and relatively insoluble. Hexavalent chromate is a strong oxidizing agent, and will react rapidly with the pyrite surface allowing the identification of oxidized iron and sulfur surface species. The possibility of using pyrite as a means of reducing chromate, and at the same time using chromate to passivate the pyrite surface to further oxidation through the buildup of a non-reactive iron-chromium (oxy)hydroxide layer will be investigated. The work was performed on rods cut from a natural pyrite single crystal from the Logroño region of Spain. The rods were then fractured over a reaction vessel, producing a fresh (100) surface for each experiment. The pyrite surfaces were reacted with 50 μM Cr(VI) solutions for 5 minutes at

  13. Aqueous U(VI) interaction with magnetite nanoparticles in a mixed flow reactor system: HR-XANES study

    Science.gov (United States)

    Pidchenko, I.; Heberling, F.; Kvashnina, KO; Finck, N.; Schild, D.; Bohnert, E.; Schäfer, T.; Rothe, J.; Geckeis, H.; Vitova, T.

    2016-05-01

    The redox variations and changes in local atomic environment of uranium (U) interacted with the magnetite nanoparticles were studied in a proof of principle experiment by the U L3 and M4 edges high energy resolution X-ray absorption near edge structure (HR-XANES) technique. We designed and applied a mixed flow reactor (MFR) set-up to maintain dynamic flow conditions during U-magnetite interactions. Formation of hydrolyzed, bi- and poly-nuclear U species were excluded by slow continuous injection of U(VI) (10-6 M) and pH control integrated in the MFR set-up. The applied U HR-XANES technique is more sensitive to minor changes in the U redox states and bonding compared to the conventional XANES method. Major U(VI) contribution in uranyl type of bonding is found in the magnetite nanoparticles after three days operation time of the MFR. Indications for shortening of the U-Oaxial bond length for the magnetite compared to the maghemite system are present too.

  14. Aqueous solutions of uranium(VI) as studied by time-resolved emission spectroscopy: a round-robin test.

    Science.gov (United States)

    Billard, Isabelle; Ansoborlo, Eric; Apperson, Kathleen; Arpigny, Sylvie; Azenha, M Emilia; Birch, David; Bros, Pascal; Burrows, Hugh D; Choppin, Gregory; Couston, Laurent; Dubois, Veronique; Fanghänel, Thomas; Geipel, Gerhard; Hubert, Solange; Kim, Jae I; Kimura, Takaumi; Klenze, Reinhardt; Kronenberg, Andreas; Kumke, Michael; Lagarde, Gerard; Lamarque, Gerard; Lis, Stefan; Madic, Charles; Meinrath, Gunther; Moulin, Christophe; Nagaishi, Ryuji; Parker, David; Plancque, Gabriel; Scherbaum, Franz; Simoni, Eric; Sinkov, Sergei; Viallesoubranne, Carole

    2003-08-01

    Results of an inter-laboratory round-robin study of the application of time-resolved emission spectroscopy (TRES) to the speciation of uranium(VI) in aqueous media are presented. The round-robin study involved 13 independent laboratories, using various instrumentation and data analysis methods. Samples were prepared based on appropriate speciation diagrams and, in general, were found to be chemically stable for at least six months. Four different types of aqueous uranyl solutions were studied: (1) acidic medium where UO2(2+)aq is the single emitting species, (2) uranyl in the presence of fluoride ions, (3) uranyl in the presence of sulfate ions, and (4) uranyl in aqueous solutions at different pH, promoting the formation of hydrolyzed species. Results between the laboratories are compared in terms of the number of decay components, luminescence lifetimes, and spectral band positions. The successes and limitations of TRES in uranyl analysis and speciation in aqueous solutions are discussed.

  15. Study of polyethyleneimine- and amidoxime-functionalized hybrid biomass of Spirulina (Arthrospira) platensis for adsorption of uranium (VI) ion.

    Science.gov (United States)

    Bayramoglu, Gulay; Akbulut, Aydin; Arica, M Yakup

    2015-11-01

    This study investigates the potential application of the polyethyleneimine- (PEI) and amidoxime-modified Spirulina (Arthrospira) platensis biomasses for the removal of uranium ion in batch mode using the native biomass as a control system. The uranium ion adsorption was also characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra, zeta potential analysis, and surface area measurement studies. The effects of pH, biomass amount, contact time, initial uranium ion concentration, and ionic strength were evaluated by using native and modified algal biomass preparations. The uranium ion removal was rapid, with more than 70% of total adsorption taking place in 40 min, and equilibrium was established within 60 min. From the experimental data, it was found that the amount of adsorption uranium ion on the algal preparations decreased in the following series: amidoxime-modified algal biomass > PEI-modified algal biomass > native algal biomass. Maximum adsorption capacities of amidoxime- and PEI-modified, and native algal biomasses were found to be 366.8, 279.5, and 194.6 mg/g, respectively, in batchwise studies. The adsorption rate of U(VI) ion by amidoxime-modified algal biomass was higher than those of the native and PEI-modified counterparts. The adsorption processes on all the algal biomass preparations followed by the Dubinin-Radushkevitch (D-R) and Temkin isotherms and pseudo-second-order kinetic models. The thermodynamic parameters were determined at four different temperatures (i.e., 15, 25, 35, and 45 °C) using the thermodynamics constant of the Temkin isotherm model. The ΔH° and ΔG° values of U(VI) ion adsorption on algal preparations show endothermic heat of adsorption; higher temperatures favor the process. The native and modified algal biomass preparations were regenerated using 10 mM HNO3. These results show that amidoxime-modified algal biomass can be a potential candidate for effective removal of U(VI) ion from

  16. Equilibrium and kinetic study on chromium (VI removal from simulated waste water using gooseberry seeds as a novel biosorbent

    Directory of Open Access Journals (Sweden)

    J. Aravind

    2015-07-01

    Full Text Available Gooseberry seed (Phyllanthus acidus was used as an adsorbent to determine its feasibility for the removal of Cr(VI. Various parameters such as pH, temperature, contact time, initial metal concentration and adsorbent dosage were investigated to determine the biosorption performance. Equilibrium was attained within 60 minutes and maximum removal of 96% was achieved under the optimum conditions at pH 2. The adsorption phenomenon demonstrated here was monolayer represented by Langmuir isotherm with R2 value of 0.992 and the Langmuir constants k and q0 was found to be 0.0061 (L/mg and 19.23 (mg/g. The adsorption system obeyed Pseudo second order kinetics with R2 value of 0.999. The results of the present study indicated that gooseberry seed powder can be employed as adsorbent for the effective removal of hexavalent chromium economically.

  17. Kinetic and thermodynamic studies on the adsorption of U(VI) ions on densely crosslinked poly(methacrylic acid) from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Oezeroglu, C.; Keceli, G. [Istanbul Univ., Dept. of Chemistry, Avcilar Istanbul (Turkey)

    2009-07-01

    In this study, densely crosslinked poly(methacrylie acid) was used to adsorb uranium(VI) ions from aqueous solution. For this purpose, the crosslinked copolymer of ethylene glycol dimethacrylate (EGDM) and methacrylic acid (MA) containing 25% (w/w) methacrylic acid (MA) was synthesized by using dibenzoyl peroxide-N,N-dimethylaniline (BPO-DMA) initiator system at room temperature. The adsorption of uranium(Vl) ions on the copolymer sample (0.02 g copolymer/5 mL solution of U(VI) ions) was carried out in a batch reactor. The parameters which effect the uranium adsorption process, such as, contact time. pH of solution, initial uranium(VI) concentration and temperature were investigated. It was observed that an increase in these parameters enhanced the removal of U(VI) ions from aqueous solution. The adsorption data were modelled by the Freundlich. Langmuir and Dubinin-Radushkevich (D-R) isotherms. The adsorption capacity of the crosslinked copolymer and free energy change were calculated by using D-R isotherms. Thermodynamic parameters ({delta}H , {delta}S and {delta}G ) were determined for the adsorption of U(VI) ions from aqueous solutions by the crosslinked copolymer bearing methacrylic acid functional groups. Experimental adsorption data were analyzed using sorption kinetic models of the pseudo-first order and pseudo-second order kinetic models. It was observed that pseudo-second order kinetic model provided a high goodness of fit with experimental data for the adsorption of U(VI) ions on the crosslinked copolymer bearing methacrylic acid functional groups. The densely crosslinked poly(methacrylic acid) might be of interest in large scale uranium removals from aqueous solution, since it had high uranyl sorption capacities ranging from 0.16 to 2.37 mmol/g copolymer at pH 2.7 (293 K). (orig.)

  18. Study on the Advertising Management of Fashion Magazines Under the Media Environment. A Case Study of"ViVi"

    Institute of Scientific and Technical Information of China (English)

    Linghu Kerui

    2015-01-01

    Magazine advertising as a major source of income, the quality of its operations is critical to the development and survival of the magazine. However, under the new media environment, traditional advertising management is no longer adapted to the times, media operators must find their own inadequacies of advertising business, through business innovation to gain a firm foothold in the competition torrent. This paper as the research object of "ViVi'" , analyzes the advertising management and the problem under the new media environment. Finally, offer the suggestion for fashion magazines to better development advertising under the new media environment.

  19. Performance Study of Chromium (VI Removal in Presence of Phenol in a Continuous Packed Bed Reactor by Escherichia coli Isolated from East Calcutta Wetlands

    Directory of Open Access Journals (Sweden)

    Bhaswati Chakraborty

    2013-01-01

    Full Text Available Organic pollutants, like phenol, along with heavy metals, like chromium, are present in various industrial effluents that pose serious health hazard to humans. The present study looked at removal of chromium (VI in presence of phenol in a counter-current continuous packed bed reactor packed with E. coli cells immobilized on clay chips. The cells removed 85% of 500 mg/L of chromium (VI from MS media containing glucose. Glucose was then replaced by 500 mg/L phenol. Temperature and pH of the MS media prior to addition of phenol were 30°C and 7, respectively. Hydraulic retention times of phenol- and chromium (VI-containing synthetic media and air flow rates were varied to study the removal efficiency of the reactor system. Then temperature conditions of the reactor system were varied from 10°C to 50°C, the optimum being 30°C. The pH of the media was varied from pH 1 to pH 12, and the optimum pH was found to be 7. The maximum removal efficiency of 77.7% was achieved for synthetic media containing phenol and chromium (VI in the continuous reactor system at optimized conditions, namely, hydraulic retention time at 4.44 hr, air flow rate at 2.5 lpm, temperature at 30°C, and pH at 7.

  20. Diverse anisotropy of phonon transport in two-dimensional group IV-VI compounds: A comparative study

    Science.gov (United States)

    Qin, Guangzhao; Qin, Zhenzhen; Fang, Wu-Zhang; Zhang, Li-Chuan; Yue, Sheng-Ying; Yan, Qing-Bo; Hu, Ming; Su, Gang

    2016-05-01

    New classes of two-dimensional (2D) materials beyond graphene, including layered and non-layered, and their heterostructures, are currently attracting increasing interest due to their promising applications in nanoelectronics, optoelectronics and clean energy, where thermal transport is a fundamental physical parameter. In this paper, we systematically investigated the phonon transport properties of the 2D orthorhombic group IV-VI compounds of GeS, GeSe, SnS and SnSe by solving the Boltzmann transport equation (BTE) based on first-principles calculations. Despite their similar puckered (hinge-like) structure along the armchair direction as phosphorene, the four monolayer compounds possess diverse anisotropic properties in many aspects, such as phonon group velocity, Young's modulus and lattice thermal conductivity (κ), etc. Especially, the κ along the zigzag and armchair directions of monolayer GeS shows the strongest anisotropy while monolayer SnS and SnSe show almost isotropy in phonon transport. The origin of the diverse anisotropy is fully studied and the underlying mechanism is discussed in details. With limited size, the κ could be effectively lowered, and the anisotropy could be effectively modulated by nanostructuring, which would extend the applications to nanoscale thermoelectrics and thermal management. Our study offers fundamental understanding of the anisotropic phonon transport properties of 2D materials, and would be of significance for further study, modulation and applications in emerging technologies.

  1. Adsorption and desorption of U(VI) on functionalized graphene oxides: a combined experimental and theoretical study.

    Science.gov (United States)

    Sun, Yubing; Yang, Shubin; Chen, Yue; Ding, Congcong; Cheng, Wencai; Wang, Xiangke

    2015-04-01

    The adsorption and desorption of U(VI) on graphene oxides (GOs), carboxylated GOs (HOOC-GOs), and reduced GOs (rGOs) were investigated by batch experiments, EXAFS technique, and computational theoretical calculations. Isothermal adsorptions showed that the adsorption capacities of U(VI) were GOs > HOOC-GOs > rGOs, whereas the desorbed amounts of U(VI) were rGOs > GOs > HOOC-GOs by desorption kinetics. According to EXAFS analysis, inner-sphere surface complexation dominated the adsorption of U(VI) on GOs and HOOC-GOs at pH 4.0, whereas outer-sphere surface complexation of U(VI) on rGO was observed at pH 4.0, which was consistent with surface complexation modeling. Based on the theoretical calculations, the binding energy of [G(···)UO2](2+) (8.1 kcal/mol) was significantly lower than those of [HOOC-GOs(···)UO2](2+) (12.1 kcal/mol) and [GOs-O(···)UO2](2+) (10.2 kcal/mol), suggesting the physisorption of UO2(2+) on rGOs. Such high binding energy of [GOs-COO(···)UO2](+) (50.5 kcal/mol) revealed that the desorption of U(VI) from the -COOH groups was much more difficult. This paper highlights the effect of the hydroxyl, epoxy, and carboxyl groups on the adsorption and desorption of U(VI), which plays an important role in designing GOs for the preconcentration and removal of radionuclides in environmental pollution cleanup applications.

  2. Biosorption of uranium(VI) from aqueous solutions by Ca-pretreated Cystoseira indica alga: breakthrough curves studies and modeling.

    Science.gov (United States)

    Ghasemi, Morteza; Keshtkar, Ali Reza; Dabbagh, Reza; Jaber Safdari, S

    2011-05-15

    Uranium(VI) biosorption from aqueous solutions containing 60 mg l(-1) metal concentration by Ca-pretreated Cystoseira indica alga was studied in a packed bed column with 1.5 cm internal diameter. The effect of bed height and flow rate on biosorption process was investigated and the experimental breakthrough curves were obtained. Results showed that by increasing the bed height, the breakthrough and exhaustion times increased and the slope of breakthrough curves decreased. Also, it was observed that the controlled-rate step shifted from external to internal mass transfer limitations, as the flow rate increased. The maximum uptake capacity, 318.15 mg g(-1), and total metal removal, 59.32%, were obtained at flow rate of 2.3 ml min(-1) and bed height of 6 cm. The column was regenerated using 0.1M HCl solution and sorption-desorption studies were carried out for three cycles. The obtained results confirmed that reusability of this biosorbent is possible. The results obtained agreed well with the bed depth service time model. In addition, for estimations of the parameters necessary for the design of a large-scale packed bed column, the experimental data were also fitted to the Thomas, Yan and Belter models and were found to agree with the experimental data fairly well.

  3. Biosorption of uranium(VI) from aqueous solutions by Ca-pretreated Cystoseira indica alga: Breakthrough curves studies and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemi, Morteza [Faculty of Nuclear Engineering, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Keshtkar, Ali Reza, E-mail: akeshtkar@aeoi.org.ir [Nuclear Fuel Cycle School, Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of); Dabbagh, Reza [Nuclear Science Research School, Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of); Jaber Safdari, S. [Nuclear Fuel Cycle School, Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of)

    2011-05-15

    Uranium(VI) biosorption from aqueous solutions containing 60 mg l{sup -1} metal concentration by Ca-pretreated Cystoseira indica alga was studied in a packed bed column with 1.5 cm internal diameter. The effect of bed height and flow rate on biosorption process was investigated and the experimental breakthrough curves were obtained. Results showed that by increasing the bed height, the breakthrough and exhaustion times increased and the slope of breakthrough curves decreased. Also, it was observed that the controlled-rate step shifted from external to internal mass transfer limitations, as the flow rate increased. The maximum uptake capacity, 318.15 mg g{sup -1}, and total metal removal, 59.32%, were obtained at flow rate of 2.3 ml min{sup -1} and bed height of 6 cm. The column was regenerated using 0.1 M HCl solution and sorption-desorption studies were carried out for three cycles. The obtained results confirmed that reusability of this biosorbent is possible. The results obtained agreed well with the bed depth service time model. In addition, for estimations of the parameters necessary for the design of a large-scale packed bed column, the experimental data were also fitted to the Thomas, Yan and Belter models and were found to agree with the experimental data fairly well.

  4. Spectroscopic study on the role of TiO{sub 2} in the adsorption of Eu(III) and U(VI) on silica surfaces in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Im, Hee-Jung, E-mail: imhj@kaeri.re.kr; Park, Kyoung Kyun; Jung, Euo Chang

    2014-10-15

    Highlights: • Enhanced adsorption of Eu(III) and U(VI) onto TiO{sub 2}-coated silica. • Enhanced Eu(III) luminescence and lifetime on TiO{sub 2}-coated silica. • Energy transfer from TiO{sub 2} of TiO{sub 2}-coated silica to Eu(III) in solutions. - Abstract: To determine the effects of TiO{sub 2} on the adsorption of actinides onto mineral surfaces in groundwater, silica was partially coated with TiO{sub 2}, and Eu(III) and U(VI) were individually adsorbed from separate 0.1 mM concentration solutions. The TiO{sub 2}-coated silica showed higher Eu(III) and U(VI) adsorption capacities for increasing amounts of TiO{sub 2} coated on the silica surfaces, and thus the existence of TiO{sub 2} can decrease the mobility of Eu(III) and U(VI) contaminants. In luminescence studies, it was found that TiO{sub 2} considerably enhanced the luminescence of the adsorbed Eu(III) indicating that TiO{sub 2}–Eu(III) forms surface complexes which may decrease the number of water molecules at the inner sphere of Eu(III), but this was not observed for U(VI). An energy transfer from the TiO{sub 2} to the Eu(III) was confirmed in this case of amorphous TiO{sub 2}-coated silica in Eu(III) solutions, and an increase of the luminescence lifetime of Eu(III) for increasing concentrations of coated TiO{sub 2} was also observed.

  5. Chromium (VI) adsorption on boehmite

    Energy Technology Data Exchange (ETDEWEB)

    Granados-Correa, F. [Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027 Col., Escandon, Delegacion Miguel Hidalgo, C.P. 11801 Mexico, D.F. (Mexico)], E-mail: fgc@nuclear.inin.mx; Jimenez-Becerril, J. [Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027 Col., Escandon, Delegacion Miguel Hidalgo, C.P. 11801 Mexico, D.F. (Mexico)

    2009-03-15

    Boehmite was synthesized and characterized in order to study the adsorption behavior and the removal of Cr(VI) ions from aqueous solutions as a function of contact time, initial pH solution, amount of adsorbent and initial metal ion concentration, using batch technique. Adsorption data of Cr(VI) on the boehmite were analyzed according to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption models. Thermodynamic parameters for the adsorption system were determinated at 293, 303, 313 and 323 K temperatures. The kinetic values and thermodynamic parameters from the adsorption process show that the Cr(VI) ions adsorption on boehmite is an endothermic and spontaneous process. These results show that the boehmite could be considered as a potential adsorbent for chromium ions in aqueous solutions.

  6. Duration of Vi antibodies in participants vaccinated with Typhim Vi (Typhoid Vi polysaccharide vaccine) in an area not endemic for typhoid fever.

    Science.gov (United States)

    Froeschle, James E; Decker, Michael D

    2010-02-10

    After a single injection of Typhim Vi (typhoid Vi polysaccharide vaccine), serum antibody concentrations were monitored for 3 years in 37 adults who resided where typhoid fever was not endemic. Anti-Vi antibody concentrations declined progressively during the study, to levels that support the current US recommendation for revaccination every 2 years.

  7. Cu vi parolas Esperante?

    Institute of Scientific and Technical Information of China (English)

    Andrzej; Pettyn

    1999-01-01

    LA DEKA LECIONOKiom da mono vi bezonas?—Barbara:Mi foriras aeti ion pormani.u vi deziras ion de mi?—Sinjoro Petro(la edzo de Barbara):Aetu por mi skatolon da cigaredoj aǔeble...aetu por mi du skatolojn dacigaredoj kaj unu skatolon da alume-toj.—B:Bone.u vi ankoraǔ deziras ion?—P:Ne,dankon.Estasio.u vihavas monon?

  8. Áreas limpas: estudo de correlação entre partículas viáveis e não-viáveis Clean rooms: a correlation study between viable and non-viable particles

    Directory of Open Access Journals (Sweden)

    Catherine Simões de Abreu

    2003-06-01

    Full Text Available Este trabalho consiste em um estudo sobre monitoramento ambiental de áreas limpas (classes A, B, C e D. Os parâmetros comparados foram partículas não-viáveis de 0,5 e 5,0 µm e de viáveis em UFC (unidades formadoras de colônias, do ambiente e de superfícies (Rodac®. As amostragens nas áreas limpas foram feitas em situações de repouso e dinâmica, antes e após sanitização, e em etapas de certificação e rotina. Os dados de literatura indicam que os parâmetros não são particularmente dependentes do lay out ou classificação das áreas, mas sim do seu uso e do comportamento dos operadores. As conclusões foram positivas quanto à correlação entre diferentes locais de amostragem, para partículas não viáveis de 0,5 e 5,0 µm, caracterizando-se, porém, ausência deste tipo de correlação nas posições em fluxo laminar. Também, os valores de correlação foram quase sempre decrescentes com a maior limpeza do ambiente. Os microrganismos mais freqüentemente isolados nas áreas B, C e D foram Bacillus sp, Staphylococcus sp e Corynebacteriumsp.This paper presents a study about environmental monitoring data for cleanrooms ( A, B, C and D classified areas. The parameters that were compared are: total airborne particles of 0.5 and 5.0 µm, airborne colony forming units (CFU's and CFU's on surfaces (Rodac®. In these areas sampling was performed "at rest" and "dynamic" conditions, before and after sanitization and during certification and routine basis. Available data in literature indicates that the parameters are not particularly dependent upon the lay out or classification of areas, but rather on the use of the areas, and the operators behaviour. Evaluating the data, the conclusion was about a correlation among different sampling places, for total airborne particles of 0.5 and 5.0 µm, and absence of this kind of correlation in laminar flows positions. Also, correlation values were always increasing with the cleanless of the

  9. Interaction of uranium(VI) with bioligands present in human biological fluids. The case study of urea and uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Osman, A.A.A.; Geipel, G.; Bernhard, G. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany). Inst. of Resource Ecology

    2013-05-01

    The complexation of uranium(VI) with bioligands found in human biological fluids, viz, urea and uric acid in aqueous solutions, has been investigated using time-resolved laser-induced fluorescence spectroscopy (TRLFS) at room temperature, I = 0.1 M (NaClO4) and pH (3 for uric acid; 4 for urea). In both complex systems a static quench effect with increasing ligand concentration and no peaks shift upon complexation were observed. With uranium(VI) both ligands formed a fairly weak 1:1 complex with average stability constants of log {beta}{sub 110} = 4.67 {+-} 0.29 for uric acid and log {beta}{sub 110} = 3.79 {+-} 0.15 and 2.12 {+-} 0.18 for relatively low and relatively high urea concentrations, respectively. Application of the newly generated data on the U(VI) speciation modelling in biofluids, e.g., human urine was also discussed.

  10. Anaerobic bio-removal of uranium (VI) and chromium (VI): Comparison of microbial community structure

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Monica [Centro de Ciencias do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Faleiro, Maria Leonor [IBB - Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Chaves, Sandra; Tenreiro, Rogerio [Universidade de Lisboa, Faculdade de Ciencias, Centro de Biodiversidade, Genomica Integrativa e Funcional (BioFIG), Campus de FCUL, Campo Grande 1749-016 Lisboa (Portugal); Santos, Erika [Centro de Ciencias do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Costa, Maria Clara, E-mail: mcorada@ualg.pt [Centro de Ciencias do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)

    2010-04-15

    Several microbial communities, obtained from uranium contaminated and non-contaminated samples, were investigated for their ability to remove uranium (VI) and the cultures capable for this removal were further assessed on their efficiency for chromium (VI) removal. The highest efficiency for removal of both metals was observed on a consortium from a non-contaminated soil collected in Monchique thermal place, which was capable to remove 91% of 22 mg L{sup -1} U(VI) and 99% of 13 mg L{sup -1} Cr(VI). This study revealed that uranium (VI) removing communities have also ability to remove chromium (VI), but when uranium (VI) was replaced by chromium (VI) several differences in the structure of all bacterial communities were observed. TGGE and phylogenetic analysis of 16S rRNA gene showed that the uranium (VI) removing bacterial consortia are mainly composed by members of Rhodocyclaceae family and Clostridium genus. On the other hand, bacteria from Enterobacteriaceae family were detected in the community with ability for chromium (VI) removal. The existence of members of Enterobacteriaceae and Rhodocyclaceae families never reported as chromium or uranium removing bacteria, respectively, is also a relevant finding, encouraging the exploitation of microorganisms with new abilities that can be useful for bioremediation.

  11. Anaerobic bio-removal of uranium (VI) and chromium (VI): comparison of microbial community structure.

    Science.gov (United States)

    Martins, Mónica; Faleiro, Maria Leonor; Chaves, Sandra; Tenreiro, Rogério; Santos, Erika; Costa, Maria Clara

    2010-04-15

    Several microbial communities, obtained from uranium contaminated and non-contaminated samples, were investigated for their ability to remove uranium (VI) and the cultures capable for this removal were further assessed on their efficiency for chromium (VI) removal. The highest efficiency for removal of both metals was observed on a consortium from a non-contaminated soil collected in Monchique thermal place, which was capable to remove 91% of 22 mg L(-1) U(VI) and 99% of 13 mg L(-1) Cr(VI). This study revealed that uranium (VI) removing communities have also ability to remove chromium (VI), but when uranium (VI) was replaced by chromium (VI) several differences in the structure of all bacterial communities were observed. TGGE and phylogenetic analysis of 16S rRNA gene showed that the uranium (VI) removing bacterial consortia are mainly composed by members of Rhodocyclaceae family and Clostridium genus. On the other hand, bacteria from Enterobacteriaceae family were detected in the community with ability for chromium (VI) removal. The existence of members of Enterobacteriaceae and Rhodocyclaceae families never reported as chromium or uranium removing bacteria, respectively, is also a relevant finding, encouraging the exploitation of microorganisms with new abilities that can be useful for bioremediation.

  12. Spin-flip-Raman studies of semimagnetic II-VI heterostructures; Spin-flip-Raman-Untersuchungen an semimagnetischen II-VI-Halbleiter-Quantentroegen und Volumenproben

    Energy Technology Data Exchange (ETDEWEB)

    Lentze, Michael

    2009-03-18

    In the present doctoral thesis, spin flip Raman studies of semimagnetic (Zn,Mn)Se samples were in the focus of interest. Quantum wells as well as bulk-like materials were investigated. The main goal was a better understanding of the exchange interaction behaviour of heavily n-doped semimagnetic samples. The influence of doping on the exchange interaction is of special relevance with regard to spintronics applications. Several series of high quality MBE-grown (Zn,Mn)Se-samples samples were available. (orig.)

  13. BASIC Simulation Programs; Volumes V and VI. Social Studies, Teacher Assistance.

    Science.gov (United States)

    Digital Equipment Corp., Maynard, MA.

    Five computer programs which teach concepts and processes related to social studies (in the main, economics) are presented. The subjects of the programs are the distinction between balance of trade and balance of payments; installment buying, loan payments, and savings accounts; flow of goods, services, and money between business and the consumer;…

  14. A study of the core of the Shapley Concentration VI. Spectral properties of galaxies

    CERN Document Server

    Baldi, A; Zucca, E; Baldi, Alessandro; Bardelli, Sandro; Zucca, Elena

    2001-01-01

    We present the results of a study of the spectral properties of galaxies in the central part of the Shapley Concentration, covering an extremely wide range of densities, from the rich cluster cores to the underlying supercluster environment. Our sample is homogeneous, in a well defined magnitude range (17=study the properties of galaxies at different densities: cluster, intercluster (i.e. galaxies in the supercluster but outside clusters) and field environment. No significant differences are present between samples at low density regimes (i.e. intercluster and field galaxies). Cluster galaxies, instead, not only have values significantly different from...

  15. Time-resolved optical studies of wide-gap II-VI semiconductor heterostructures

    Science.gov (United States)

    Wang, Hong

    ZnSe and ZnSe-based quantum well and superlattice structures are potential candidates for light emitting devices and other optical devices such as switches and modulators working in the blue-green wavelength range. Carrier dynamics studies of these structures are important in evaluating device performance as well as understanding the underlying physical processes. In this thesis, a carrier dynamics investigation is conducted for temperature from 77K to 295K on CdZnSSe/ZnSSe single quantum well structure (SQW) and ZnSe/ZnSTe superlattice fabricated by molecular beam epitaxy (MBE). Two experimental techniques with femtosecond time resolution are used in this work: up-conversion technique for time- resolved photoluminescence (PL) and pump-probe technique for time-resolved differential absorption studies. For both heterostructures, the radiative recombination is dominated by exciton transition due to the large exciton binding energy as a result of quantum confinement effect. The measured decay time of free exciton PL in CdZnSSe/ZnSSe SQW increases linearly with increasing temperature which agrees with the theoretical prediction by considering the conservation of momentum requirement for radiative recombination. However, the recombination of free carriers is also observed in CdZnSSe/ZnSSe SQW for the whole temperature range studied. On the other hand, in ZnSe/ZnSTe superlattice structures, the non- radiative recombination processes are non-negligible even at 77K and become more important in higher temperature range. The relaxation processes such as spectral hole burning, carrier thermalization and hot-carrier cooling are observed in ZnSe/ZnSTe superlattices at room temperature (295K) by the femtosecond pump-probe measurements. A rapid cooling of the thermalized hot- carrier from 763K to 450K within 4ps is deduced. A large optical nonlinearity (i.e., the induced absorption change) around the heavy-hole exciton energy is also obtained.

  16. A study of nanostructured gold modified glassy carbon electrode for the determination of trace Cr(VI)

    Indian Academy of Sciences (India)

    Benzhi Liu; Liyuan Lu; Min Wang; Yanqin Zi

    2008-09-01

    A nanostructured gold modified glassy carbon electrode (Aunano/GCE) was employed for the determination of trace chromium(VI). To prepare Aunano/GCE, the GCE was immersed into KAuCl4 solution and electrodeposition was conducted at the potential of -0.4 V (vs Ag/AgCl) for 600 s. Scanning electron microscopy measurements show that the electrochemically synthesized gold nanoparticles were deposited in aggregated form. Any undue effects caused by the presence of foreign ions in the solution were also analysed to ensure that common interference in the determination of chromium(VI) by square wave voltammetry, do not influence the electrochemical response of the latter element. The results show that this method allows for Cr(VI) determinations with a much lower detection limit (0.01 g L-1) in the presence of excess of Cr(III) than the commonly used diethylenetriammine pentaacetic acid (DTPA) method. The method was applied to determine levels of chromium(VI) in tap water and sewage water.

  17. On the passivation mechanism of Fe3O4 nanoparticles during Cr(VI) removal from water: A XAFS study

    Science.gov (United States)

    Pinakidou, F.; Katsikini, M.; Simeonidis, K.; Kaprara, E.; Paloura, E. C.; Mitrakas, M.

    2016-01-01

    X-Ray Absorption Spectroscopies (XAFS) are employed in order to gather a thorough insight on the uptake mechanism of Cr(VI) by Fe3O4 nanoparticles under water treatment conditions. The XANES measurements identify that the reducing potential of Fe3O4 activates the precipitation of Cr(VI) in the form of insoluble and non-toxic Cr(III). However, electron donation from Fe(II) is responsible for its gradual consumption, resulting in the presence of a surface maghemite layer and the formation of structural vacancies. EXAFS analysis reveal that adsorption of Cr(III)-oxyanions occurs on sorption sites provided by the vacancies in the maghemite layer, where Cr(III) is involved in a bidentate binuclear (2E) geometry with Fe-octahedra while it also forms monodentate (1V) complexes with the Fe(III)O4 tetrahedra. The surface maghemitization along with the reduced Cr(III) adsorption into the vacancies, tracks the degree of Cr-reduction, since this surface structural modifications hinder Cr(VI) access to the Fe(II) ions of the magnetite nanoparticles. Thus, high surface coverage leads to the passivation of the reduction ability since physisorbed Cr(VI) is also detected through the formation of outer sphere complexes.

  18. [Leaf anatomic studies in solanaceae of Venezuela. VI. Leaf anatomy of 10 species of Cestrum L].

    Science.gov (United States)

    Jáuregui, D; de Ríos, N R; Benítez de Rojas, C E

    2001-01-01

    The leaf anatomy of Cestrum acuminatissimum Dunal, C. alternifolium (Jacq.) O.E. Schulz, C. glabrescens (C.V. Morton) Steyerm. et Maguire, C. imbricatum Rusby, C. Iatifolium Lam., C. neblinense D'Arcy et Benítez, C. ruizteranianum Benítez et D'Arcy, C. schulzianum Francey, C. tillettii Benítez et D'Arcy y C. tubulosum Sendtner, is described in order to value its diagnostic characters useful as source of data in the taxonomy of the Solanaceae. The material was obtained from specimens deposited in MY herbarium, coming from different geographical areas of Venezuela, and it was prepared according the classical methodology used in leaf anatomy studies. The results obtained have, besides the common features mentions for other species of the genus Cestrum, some differences in: types and density of trichomes, thickness and sinuousities of the cell wall, stomata position, as well as in the distribution of esclerenchymatous cells of the mesophyll, midvein petiole.

  19. Ab initio electronic band structure study of III-VI layered semiconductors

    Science.gov (United States)

    Olguín, Daniel; Rubio-Ponce, Alberto; Cantarero, Andrés

    2013-08-01

    We present a total energy study of the electronic properties of the rhombohedral γ-InSe, hexagonal ɛ-GaSe, and monoclinic GaTe layered compounds. The calculations have been done using the full potential linear augmented plane wave method, including spin-orbit interaction. The calculated valence bands of the three compounds compare well with angle resolved photoemission measurements and a discussion of the small discrepancies found has been given. The present calculations are also compared with recent and previous band structure calculations available in the literature for the three compounds. Finally, in order to improve the calculated band gap value we have used the recently proposed modified Becke-Johnson correction for the exchange-correlation potential.

  20. Cu vi parolas Esperante?

    Institute of Scientific and Technical Information of China (English)

    Andrzej; Pettyn

    2000-01-01

    LA DEKKVARA LEOIONOMi havas por vi surprizon—Barbara:Bonan matenon!—Petro:Bonan matenon,mia kara!—B Mi havas pot vi surprizon.—P:Viiam havas pot mi surprizojn.—B:Sed hodiaǔ mi parolas treserioze."Okaze de via naskitago ak-

  1. Electronic properties of the layer III-VI semiconductors. A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Depeursinge, Y. (Ecole Polytechnique Federale, Lausanne (Switzerland). Lab. de Physique Appliquee)

    1981-07-11

    The electronic properties of the family of layer compounds InSe, GaSe and GaS by the empirical pseudopotential method have been studied. Both atomic positions, which are not accurately known from experiment, and atomic pseudopotentials are adjusted to fit the main optical and photoemission data with the further constraint that the same Se potential should be valid for InSe and GaSe, and the same Ga potential for GaS and GaSe. The charge densities have also been calculated and show that the ionicity of InSe is greater than that of GaS and GaSe, in good agreement with the Phillips electronegativity scale which predicts that InSe is 1.2 and 1.3 times more ionic than GaS and GaSe, respectively. The calculated band structures and charge densities allow a detailed discussion of the integrated and angle-resolved photoemission data as well as of the optical properties of these compounds.

  2. Study of Mo (VI Removal from Aqueous Solution: Application of Different Mathematical Models to Continuous Biosorption Data

    Directory of Open Access Journals (Sweden)

    Fatemeh Kafshgari

    2013-01-01

    Full Text Available Molybdenum (VI biosorption process was investigated by marine algae Cystoseria indica pretreated with 0.1 M CaCl2 solution in a packed bed column. The biosorbent was characterized by FTIR, BET and SEM analyses. The results showed that Mo (VI ions should be chelated with the hydroxyl, carboxyl and amine groups of the biomass. The effects of inlet metal concentration and flow rate on biosorption process were investigated and the experimental breakthrough curves were obtained. Results showed that the maximum biosorption capacity of Ca-pretreated C. indica for Mo (VI was found to be 18.32 mg/g at optimum flow rate of (1.4 mL/min. The controlled-rate step shifted from external to internal mass transfer limitations, as the flow rate increased. Also, it was observed that the breakthrough and exhaustion time decreased from 17.14 hr to 9.05 hr and from 0.006 h to 0.002 hr respectively, with the increase of flow rate from 0.7 to 2.1 ML/min. The increase in the initial concentration of Mo (VI solution from 30 to 95 ml min-1 increases the adsorption capacity from 18.32 to 30.19 mg/g and decreases the percentage of Mo (VI removal from 61 to 38%. Also, the treated volume was the greatest (1.42 L at the lowest inlet concentration. Column data obtained under different conditions were described using the Thomas, Yoon and Nelson, Yan and Belter models. The breakthrough curve predictions by Belter model were found to be very satisfactory.

  3. Study of Mo (VI) removal from aqueous solution: application of different mathematical models to continuous biosorption data.

    Science.gov (United States)

    Kafshgari, Fatemeh; Keshtkar, Ali Reza; Mousavian, Mohammad Ali

    2013-01-25

    Molybdenum (VI) biosorption process was investigated by marine algae Cystoseria indica pretreated with 0.1 M CaCl2 solution in a packed bed column. The biosorbent was characterized by FTIR, BET and SEM analyses. The results showed that Mo (VI) ions should be chelated with the hydroxyl, carboxyl and amine groups of the biomass. The effects of inlet metal concentration and flow rate on biosorption process were investigated and the experimental breakthrough curves were obtained. Results showed that the maximum biosorption capacity of Ca-pretreated C. indica for Mo (VI) was found to be 18.32 mg/g at optimum flow rate of (1.4 mL/min). The controlled-rate step shifted from external to internal mass transfer limitations, as the flow rate increased. Also, it was observed that the breakthrough and exhaustion time decreased from 17.14 hr to 9.05 hr and from 0.006 h to 0.002 hr respectively, with the increase of flow rate from 0.7 to 2.1 ML/min. The increase in the initial concentration of Mo (VI) solution from 30 to 95 ml min-1 increases the adsorption capacity from 18.32 to 30.19 mg/g and decreases the percentage of Mo (VI) removal from 61 to 38%. Also, the treated volume was the greatest (1.42 L) at the lowest inlet concentration. Column data obtained under different conditions were described using the Thomas, Yoon and Nelson, Yan and Belter models. The breakthrough curve predictions by Belter model were found to be very satisfactory.

  4. Study of Mo (VI removal from aqueous solution: application of different mathematical models to continuous biosorption data

    Directory of Open Access Journals (Sweden)

    Kafshgari Fatemeh

    2013-01-01

    Full Text Available Abstract Molybdenum (VI biosorption process was investigated by marine algae Cystoseria indica pretreated with 0.1 M CaCl2 solution in a packed bed column. The biosorbent was characterized by FTIR, BET and SEM analyses. The results showed that Mo (VI ions should be chelated with the hydroxyl, carboxyl and amine groups of the biomass. The effects of inlet metal concentration and flow rate on biosorption process were investigated and the experimental breakthrough curves were obtained. Results showed that the maximum biosorption capacity of Ca-pretreated C. indica for Mo (VI was found to be 18.32 mg/g at optimum flow rate of (1.4 mL/min. The controlled-rate step shifted from external to internal mass transfer limitations, as the flow rate increased. Also, it was observed that the breakthrough and exhaustion time decreased from 17.14 hr to 9.05 hr and from 0.006 h to 0.002 hr respectively, with the increase of flow rate from 0.7 to 2.1 ML/min. The increase in the initial concentration of Mo (VI solution from 30 to 95 ml min-1 increases the adsorption capacity from 18.32 to 30.19 mg/g and decreases the percentage of Mo (VI removal from 61 to 38%. Also, the treated volume was the greatest (1.42 L at the lowest inlet concentration. Column data obtained under different conditions were described using the Thomas, Yoon and Nelson, Yan and Belter models. The breakthrough curve predictions by Belter model were found to be very satisfactory.

  5. Coordination mode of nitrate in uranyl(VI) complexes: a first-principles molecular dynamics study.

    Science.gov (United States)

    Bühl, Michael; Diss, Romain; Wipff, Georges

    2007-06-25

    According to Car-Parrinello molecular dynamics simulations for [UO(2)(NO(3))(3)](-), [UO(2)(NO(3))(4)](2-), and [UO(2)(OH(2))(4-)(NO(3))](+) complexes in the gas phase and in aqueous solution, the nitrate coordination mode to uranyl depends on the interplay between ligand-metal attractions, interligand repulsions, and solvation. In the trinitrate, the eta(2)-coordination is clearly favored in water and in the gas phase, leading to a coordination number (CN) of 6. According to pointwise thermodynamic integration involving constrained molecular dynamics simulations, a change in free energy of +6 kcal/mol is predicted for eta(2)- to eta(1)-transition of one of the three nitrate ligands in the gas phase. In the gas phase, the mononitrate-hydrate complex also prefers a eta(2)-binding mode but with a CN of 5, one H(2)O molecule being in the second shell. This contrasts with the aqueous solution where the nitrate binds in a eta(1)-fashion and uranyl coordinates to four H2O ligands. A driving force of ca. -3 kcal/mol is predicted for the eta(2)- to eta(1)- transition in water. This structural preference is interpreted in terms of steric arguments and differential solvation of terminal vs uranyl-coordinated O atoms of the nitrate ligands. The [UO(2)(NO(3))(4)](2-) complex with two eta(2)- and two eta(1)- coordinated nitrates, observed in the solid state, is stable for 1-2 ps in the gas phase and in solution. In the studied series, the modulation of uranyl-ligand distances upon immersion of the complex in water is found to depend on the nature of the ligand and the composition of the complex.

  6. X-ray absorption fine structure and X-ray excited optical luminescence studies of II-VI semiconducting nanostructures

    Science.gov (United States)

    Murphy, Michael Wayne

    2010-06-01

    Various II-VI semiconducting nanomaterials such as ZnO-ZnS nanoribbons (NRs), CdSxSe1-x nanostructures, ZnS:Mn NRs, ZnS:Mn,Eu nanoprsims (NPs), ZnO:Mn nanopowders, and ZnO:Co nanopowders were synthesized for study. These materials were characterized by techniques such as scanning electron microscopy, transmission electron microscopy, element dispersive X-ray spectroscopy, selected area electron diffraction, and X-ray diffraction. The electronic and optical properties of these nanomaterials were studied by X-ray absorption fine structure (XAFS) spectroscopy and X-ray excited optical luminescence (XEOL) techniques, using tuneable soft X-rays from a synchrotron light source. The complementary nature ofthe XAFS and XEOL techniques give site, element and chemical specific measurements which allow a better understanding of the interplay and role of each element in the system. Chemical vapour deposition (CVD) of ZnS powder in a limited oxygen environment resulted in side-by-side biaxial ZnO-ZnS NR heterostructures. The resulting NRs contained distinct wurtzite ZnS and wurtzite ZnO components with widths of 10--100 nm and 20 --500 nm, respectively and a uniform interface region of 5-15 nm. XAFS and XEOL measurements revealed the luminescence of ZnO-ZnS NRs is from the ZnO component. The luminescence of CdSxSe1-x nanostructures is shown to be dependent on the S to Se ratio, with the band-gap emission being tunable between that of pure CdS and CdSe. Excitation of the CdSxSe 1-x nanostructures by X-ray in XEOL has revealed new de-excitation channels which show a defect emission band not seen by laser excitation. CVD of Mn2+ doped ZnS results in nanostructures with luminescence dominated by the yellow Mn2+ emission due to energy transfer from the ZnS host to the Mn dopant sites. The addition of EuCl3 to the reactants in the CVD process results in a change in morphology from NR to NP. Zn1-xMnxO and Zn1-xCOxO nanopowders were prepared by sol-gel methods at dopant concentrations

  7. 伤寒Vi-rEPA结合疫苗在小鼠中的免疫原性研究%Immunogenicity study of typhoid Vi-rEPA conjugate vaccine in mice

    Institute of Scientific and Technical Information of China (English)

    蒲江; 杜琳; 谭小梅; 侯亚莉; 蒋奕; 金学敏; 谢贵林

    2004-01-01

    以伤寒Vi多糖疫苗及结合物含量分别为20%、40%、60%的伤寒Vi-rEPA结合疫苗经皮下免疫小鼠后眼眶采血分离血清,用ELISA法测血清抗体浓度.血清抗体分析表明,伤寒Vi多糖疫苗和伤寒Vi-rEPA结合疫苗均有良好的免疫原性,但伤寒Vi-rEPA结合疫苗的免疫原性优于伤寒Vi多糖疫苗;伤寒Vi多糖疫苗无加强免疫应答效应,而伤寒Vi-rEPA结合疫苗有加强免疫应答效应;不同高分子结合物含量的伤寒Vi-rEPA结合疫苗免疫小鼠,其结合物含量为40%、60%的伤寒Vi-rEPA结合疫苗比结合物含量为20%的结合疫苗具有更好的免疫原性,而前二者的免疫原性无显著性差异.

  8. A spectroscopic study of the effect of ligand complexation on the reduction of uranium(VI) by anthraquinone-2,6-disulfonate (AH{sub 2}DS)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Z.; Wagnon, K.B.; Ainsworth, C.C.; Liu, C.; Rosso, K.M.; Fredrickson, J.K. [Pacific Northwest National Lab., Richland, WA (United States)

    2008-07-01

    In this paper, the reduction rate of uranyl complexes with hydroxide, carbonate, EDTA, and desferriferrioxamine B (DFB) by anthraquinone-2,6-disulfonate (AH{sub 2}DS) is studied by stopped-flow kinetic technique under anoxic atmosphere. The apparent reaction rates varied with ligand type, solution pH, and U(VI) concentration. For each ligand, a single largest pseudo-1{sup st} order reaction rate constant, k{sub obs}, within the studied pH range was observed, suggesting the influence of pH-dependent speciation on the U(VI) reduction rate. The maximum reaction rate found in each case followed the order of OH{sup -} > CO{sub 3}{sup 2-} > EDTA > DFB, in reverse order of the trend of the thermodynamic stability of the uranyl complexes and ionic sizes of the ligands. The pH-dependent rates were modeled using a second-order rate expression that was assumed to be dependent on a single U(VI) complex and an AH{sub 2}DS species. By quantitatively comparing the calculated and measured apparent rate constants as a function of pH, species AHDS{sup 3-} was suggested as the primary reductant in all cases examined. Species UO{sub 2}CO{sub 3}(aq), UO{sub 2}HEDTA{sup -}, and (UO{sub 2}){sub 2}(OH){sub 2}{sup 2+} were suggested as the principal electron acceptors among the U(VI) species mixture in each of the carbonate, EDTA, and hydroxyl systems, respectively. (orig.)

  9. STUDY ON FEASIBILITY AND LOGISTICS OF VACCINATION WITH TYPHOID VI-VACCINE ON SCHOOL CHILDREN IN NORTH JAKARTA INDONESIA: ANALYSIS OF THE VACCINATION COST

    Directory of Open Access Journals (Sweden)

    Roy G.A. Massie

    2012-11-01

    Full Text Available Background: In recent years, Indonesia government has become increasingly concerned with the issues of financing childhood vaccines and immunization programs including vaccine for typhoid  fever. The objective of the analysis is to provide alternative resources and to provide understandable data generated from the Study on Feasibility and Logistics of Vaccination School Age Children With Typhoid Vi-Vaccine in North Jakarta Indonesia. Methods: The analysis was focus on measurement of the cost for vaccinating school children with Typhoid Vi-vaccine from 18 selected primary schools in North Jakarta. The primary source of data was generated from the actual expenditures that were used in the vaccine delivery program in Indonesia. Results: The Vaccination Cost from the Study on Feasibility and Logistics of Vaccination School Age Children with Typhoid Vi-Vaccine conducted by DOMI project is not applicable for public vaccination program. The program might be feasible to be delivered only in private health sector settings.   Key words: Immunization expenditure, vaccine for typhoid fever, North Jakarta Indonesia

  10. Metal (Hydr)oxides for the removal of Cr(VI) from drinking water: a XAFS study

    Science.gov (United States)

    Pinakidou, F.; Kaprara, E.; Katsikini, M.; Paloura, E. C.; Simeonidis, K.; Mitrakas, M.

    2016-05-01

    The reduction mechanism and adsorption behaviour of Cr(VI) onto Tin(II) oxy- hydroxides are investigated using Cr-K edge X-ray absorption fine structure (XAFS) spectroscopies. The synthesis of the Sn oxy-hydroxide proceeds via hydrolysis of SnSO4. The successful reduction of Cr(VI) was identified by the analysis of the Cr-K edge XANES spectra where only Cr(III) species in octahedral sites are detected. According to the Cr-K edge EXAFS analysis results, Cr(III) forms bidentate inner sphere (binuclear (2C) and mononuclear (2E)) complexes. However, the surface coverage of Cr affects the type of Cr(III)-complexes formed: as the Cr-loading increases, Cr(III)-oxy-anions preferentially sorb in a “combined” 2C and 1V configuration, at the expense of the existing 2E sorption geometry.

  11. Ground- and excited-state stability of the conformers of 3,5-dinitrocatechol and its complexes with W(VI) and V(V): combined theoretical and experimental study.

    Science.gov (United States)

    Delchev, V B; Gavazov, K B; Shterev, I G

    2014-12-01

    We performed a theoretical and experimental study of the (photo)stability of 3,5-dinitrocatechol (DNC) and its complexes with W(VI) and V(V). The investigation showed that irradiation of DNC is accompanied by a parallel proton migration from the hydroxy group to the neighboring NO2 group, which results in a large Stokes shift of the absorption and emission bands. It was found that W(VI) forms a more stable 1:2 complex than V(V). The complex is stable even under UV irradiation. The most stable W(VI)(DNC)2 conformer is comprised of two mutually perpendicular DNC molecules as ligands.

  12. Study of uranium (VI) in carbonate solution by potentiometric titrations and ion-exchange; Etude des solutions d'uranium (VI) en milieu carbonate par titrages potentiometriques et echange d'ions

    Energy Technology Data Exchange (ETDEWEB)

    Billon, A. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-04-01

    The present work is devoted to the fixation of uranium (VI) on the conventional anion-exchange resin Dowex 2 X 8 in carbonate and hydrogen-carbonate media. Both media were successfully used for the recuperation of uranium (VI) from very dilute solutions. Equilibrium constant of the exchange [UO{sub 2}(CO{sub 3}){sub 3}{sup 4+}]{sub S} + 2 [CO{sub 3}{sup 2-}]{sub R} {r_reversible} [UO{sub 2}(CO{sub 3}){sub 3}{sup 4-}]{sub R} + 2[CO{sub 3}{sup 2-}]{sub S} is determined for carbonate concentration range 0.1 M to 0.6 M from partition curves. A markedly increase in the relative fixation of uranium results with: - increasing free carbonate concentration of the solution, - decreasing uranium concentration. A study in the same conditions of the fixation of molybdenum has made it possible to separate the latter from uranium by elution, the carbonate concentration being molar. It is suggested a possibility of separation on a larger scale, based upon molybdenum displacement by uranium in hydrogen-carbonate medium. (author) [French] Le present travail precise la fixation de l'uranium (VI) sur la resine echangeuse d'anions Dowex 2 X 8, en milieu carbonate et hydrogeno-carbonate. Nous en avons deduit que ces deux milieux sont egalement favorables a la recuperation de l'uranium a partir de solutions tres diluees. La constante d'equilibre de la reaction d'echange [UO{sub 2}(CO{sub 3}){sub 3}{sup 4+}]{sub S} + 2 [CO{sub 3}{sup 2-}]{sub R} {r_reversible} [UO{sub 2}(CO{sub 3}){sub 3}{sup 4-}]{sub R} + 2[CO{sub 3}{sup 2-}]{sub S} a ete determinee pour le milieu carbonate 0.1 M a 0.6 M, a partir deb courbes de partage. La fixation relative de l'uranium augmente considerablement lorsque: - la concentration du carbonate libre (respectivement hydrogenocarbonate) diminue, - la concentration de l'uranium en solution diminue. Le comportement du molybdene a ete etudie en vue de la separation uranium-molybdene. L'ion fixe sur la resine est l

  13. Study of epidemiological risk of lung cancer in Mexico due indoor radon exposure

    Science.gov (United States)

    Ángeles, A.; Espinosa, G.

    2014-07-01

    In this work the lifetime relative risks (LRR) of lung cancer due to exposure to indoor 222Rn on the Mexican population is calculated. Cigarette smoking is the number one risk factor for lung cancer (LC), because that, to calculate the number of cases of LC due to exposure to 222Rn is necessary considers the number of cases of LC for smoking cigarette. The lung cancer mortality rates published by the "Secretaría de Salud" (SSA), the mexican population data published by the "Consejo Nacional de Población" (CONAPO), smoking data in the mexican population, published by the "Comisión Nacional Contra las Adicciones" (CONADIC), the "Organización Panamericana de la Salud" (OPS) and indoor 222Rn concentrations in Mexico published in several recent studies are used. To calculate the lifetime relative risks (LRR) for different segments of the Mexican population, firstly the Excess Relative Risk (ERR) is calculated using the method developed by the BEIR VI committee and subsequently modified by the USEPA and published in the report "EPA Assessment of Risks from Radon in Homes". The excess relative risks were then used to calculate the corresponding lifetime relative risks, again using the method developed by the BEIR VI committee. The lifetime relative risks for Mexican male and female eversmokers and Mexican male and female never-smokers were calculated for radon concentrations spanning the range found in recent studies of indoor radon concentrations in Mexico. The lifetime relative risks of lung cancer induced by lifetime exposure to the mexican average indoor radon concentration were estimated to be 1.44 and 1.40 for never-smokers mexican females and males respectively, and 1.19 and 1.17 for ever-smokers Mexican females and males respectively. The Mexican population LRR values obtained in relation to the USA and Canada LRR published values in ever-smokers for both gender are similar with differences less than 4%, in case of never-smokers in relation with Canada

  14. Vi, de civiliserede

    DEFF Research Database (Denmark)

    Nyemann, Dorthe

    2016-01-01

    Vi har i årtier troet på, at mennesker under de rette omstændigheder kan lykkes med at leve i fred og fordragelighed med hinanden. Skal vi til at erkende, at også vores samfundsstrukturer kun er en tynd fernis ovenpå et utæmmeligt voldspotentiale og egoisme?......Vi har i årtier troet på, at mennesker under de rette omstændigheder kan lykkes med at leve i fred og fordragelighed med hinanden. Skal vi til at erkende, at også vores samfundsstrukturer kun er en tynd fernis ovenpå et utæmmeligt voldspotentiale og egoisme?...

  15. LABORATORY STUDY FOR THE REDUCTION OF CHROME (VI) TO CHROME (III) USING SODIUM METABISULFITE UNDER ACIDIC CONDITIONS

    Energy Technology Data Exchange (ETDEWEB)

    DUNCAM JB; GUTHRIE MD; LUECK KJ; AVILA M

    2007-07-18

    This report describes the results from RPP-PLAN-32738, 'Test Plan for the Effluent Treatment Facility to Reduce Chrome(VI) to Chrome(I1I) in the Secondary Waste Stream', using sodium metabisulfite. Appendix A presents the report as submitted by the Center for Laboratory Sciences (CLS) to CH2M HILL Hanford Group, Inc. The CLS carried out the laboratory effort under Contract Number 21065, release Number 30. This report extracts the more pertinent aspects of the laboratory effort.

  16. Synthesis and spectroscopic studies of 4-phenylacetyl-3-methyl-1-phenylpyrazolone-5 and its thorium(VI), lanthanum(III) and lead(II) complexes

    Science.gov (United States)

    Uzoukwu, Bieluonwu Augustus; Adiukwu, Patricia Ugboaku

    1995-12-01

    The synthesis of 4-phenylacetyl-3-methyl-1-phenylpyrazolone-5 is reported. Analysis of its IR and NMR spectral data has revealed that the ligand is bidentate and has spectral properties that resemble neither those of the 4-benzoyl, 4-acetyl derivatives nor those of the trihaloacetyl derivatives which have p Ka values complexes were isolated and characterized by UV, IR and 1H, 13C NMR spectral studies. The complexes were anhydrous and conform to a general molecular formula ML n where M( n) is Th(VI), La(III), Pb(II).

  17. A sup 183 W NMR study of mononuclear tungsten(VI) methyl complexes containing terminal oxo, sulfido, and imido ligands

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yinong; Demou, P.; Faller, J.W. (Yale Univ., New Haven, CT (USA))

    1991-01-01

    The {sup 183}W chemical shifts of a number of organometallic oxo-, sulfido-, and imido-tungsten(VI) complexes have been measured by indirect detection using {sup 1}H({sup 183}W) double-resonance and {sup 1}H({sup 1}H, {sup 183}W) triple-resonance techniques. The shielding trends within a series of ligands, including O{sup 2{minus}}, S{sup 2{minus}}, PhN{sup 2{minus}}, Cl{sup {minus}}, Br{sup {minus}}, {eta}{sup 2}-O{sub 2}{sup 2{minus}}, and {eta}{sup 2}-S{sub 2}{sup 2{minus}}, are discussed with respect to ligand polarizability and bond multiplicity. The tungsten(VI) nuclei become more deshielded with increasing ligand polarizability and bond multiplicity. The {sup 183}W chemical shifts of Cp*W({double bond}O)X{sub 2}Me complexes show an inverse halogen dependence, as expected from relative polarizability arguments. 16 refs., 2 tabs.

  18. Spectrophotometric and Calorimetric Studies of U(VI) Complexation with Sulfate at 25-70oC

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Guoxin; Rao, Linfeng

    2008-10-30

    Sulfate, one of the inorganic constituents in the groundwater of nuclear waste repository, could affect the migration of radioactive materials by forming complexes. Spectrophotometric and microcalorimetric titrations were performed to identify the U(VI)/sulfate complexes and determine the equilibrium constants and enthalpy of complexation at 25-70 C. Results show that U(VI) forms moderately strong complexes with sulfate, i.e., UO{sub 2}SO{sub 4}(aq) and UO{sub 2}(SO{sub 4}){sub 2}{sup 2-}, in this temperature range and the complexes become stronger as the temperature is increased: 2-fold and 10-fold increases in the stability constants of UO{sub 2}SO{sub 4}(aq) and UO{sub 2}(SO{sub 4}{sub 2}{sup 2-}), respectively, when the temperature is increased from 25 C to 70 C. The complexation is endothermic and entropy-driven, showing typical characteristics of inner-sphere complexation and 'hard acid'/'hard base' interactions. The thermodynamic trends are discussed in terms of dehydration of both the cation (UO{sub 2}{sup 2+}) and the anion (SO{sub 4}{sup 2-}) as well as the effect of temperature on the structure of water.

  19. Does the presence of microplastics influence the acute toxicity of chromium(VI) to early juveniles of the common goby (Pomatoschistus microps)? A study with juveniles from two wild estuarine populations.

    Science.gov (United States)

    Luís, Luís G; Ferreira, Pedro; Fonte, Elsa; Oliveira, Miguel; Guilhermino, Lúcia

    2015-07-01

    presence of MP, the negative effect caused by high concentrations of Cr(VI) on the predatory performance was significantly reduced in L-est fish but not in M-est fish, and Cr(VI) concentrations higher than 3.9mg/l caused oxidative damage in L-est fish but not in M-est fish. The acclimatization and test conditions were similar for fish from the two estuaries and these ecosystems have environmental differences. Thus, long-term exposure to distinct environmental conditions in the natural habitat during previous developmental phases influenced the sensitivity and responses of juveniles to Cr(VI), therefore, we rejected hypothesis 3. Overall, the results of this study indicate toxicological interactions between MP and Cr(VI) highlighting the importance of further investigating the combined effects of MP and other common contaminants.

  20. Engineering Test Satellite VI (ETS-VI)

    Science.gov (United States)

    Horii, M.; Funakawa, K.

    1991-01-01

    The Engineering Test Satellite-VI (ETS-VI) is being developed as the third Japanese three-axis stabilized engineering test satellite to establish the 2-ton geostationary operational satellite bus system and to demonstrate the high performance satellite communication technology for future operational satellites. The satellite is expected to be stationed at 154 deg east latitude. It will be launched from the Tanegashima Space Center in Japan by a type H-II launch vehicle. The Deep Space Network (DSN) will support the prelaunch compatibility test, data interface verification testing, and launch rehersals. The DSN primary support period is from launch through the final AEF plus 1 hour. Contingency support is from final AEF plus 1 hour until launch plus 1 month. The coverage will consist of all the 26-m antennas as prime and the 34-m antennas at Madrid and Canberra as backup. Maximum support will consist of two 8-hour tracks per station for a 7-day period, plus the contingency support, if required. Information is given in tabular form for DSN support, telemetry, command, and tracking support responsibility.

  1. Diverse anisotropy of phonon transport in two-dimensional IV-VI compounds: A first-principles study

    CERN Document Server

    Qin, Guangzhao; Fang, Wu-Zhang; Zhang, Li-Chuan; Yue, Sheng-Ying; Yan, Qing-Bo; Hu, Ming; Su, Gang

    2016-01-01

    New class two-dimensional (2D) materials beyond graphene, including layered and non-layered, and their heterostructures, are currently attracting increasing interest due to their promising applications in nanoelectronics, optoelectronics and clean energy, where thermal transport property is one of the fundamental physical parameters. In this paper, we systematically investigated the phonon transport properties of 2D orthorhombic IV-VI compounds of $GeS$, $GeSe$, $SnS$ and $SnSe$ by solving the Boltzmann transport equation (BTE) based on first-principles calculations. Despite the similar puckered (hinge-like) structure along the armchair direction as phosphorene, the four monolayer compounds possess diverse anisotropic properties in many aspects, such as group velocity, Young's modulus and lattice thermal conductivity ($\\kappa$), etc. Especially, the $\\kappa$ along the zigzag and armchair directions of monolayer $GeS$ shows the strongest anisotropy while monolayer $SnS$ and $SnSe$ shows an almost isotropy in p...

  2. Seroprevalence of anti Vi antibodies and immunogenicity of Typhim Vi vaccine in children.

    Science.gov (United States)

    Gupta, Divya; Faridi, M M A; Aggarwal, Anju; Kaur, Iqbal

    2008-01-01

    This prospective study was carried out on 250 children between 6 months to 5 years of age to determine seroprevalence of anti Vi antibodies and to measure seroresponse and percent seroconversion to TyphimVi polysaccharide vaccine in children 2-5 years of age. Fifty children each were enrolled between 6 to 12 months of age (Group A), between 1- 2 years of age(Group B), between 2-3 years of age (Group C), between 3-4 years of age (Group D) and between 4-5 years of age (Group E). Anti-Vi antibody baseline titres were determined in all children. Children in Groups C to E were vaccinated with Typhim Vi vaccine. Baseline and postvaccination antibody titres were determined by ELISA. Test sera which had antibody levels >1 microg/ml were scored as seropositive. Of 250 children, 3 had base line anti-Vi antibodies >1 microg/ml. Following immunization overall seroconversion rate was 77.5% with 65.3%, 78.2% and 88% children showing seroconversion in Groups C, D and E respectively. Seroconversion was significantly more in Group E children compared to Group C (p=0.0148). There were no significant adverse reactions following vaccination. The study highlights very low prevalence of baseline anti Vi antibodies in children between 6 months and less than 5 years of age and shows high immunogenicity and safety of Typhim Vi polysaccharide vaccine in children 2-5 years of age.

  3. Study of molybdenum (VI) complexation and precipitation by zirconium (IV) in strongly acid medium. Application to nuclear spent fuel dissolution; Etude de la complexation et de la precipitation du molybdene (VI) par le zirconium (IV) en milieu tres acide. Application a la dissolution du combustible nucleaire irradie

    Energy Technology Data Exchange (ETDEWEB)

    Esbelin, E

    1999-07-01

    These last years the formation of solid deposits has been observed in the dissolution workshops of the La Hague plant. A sample of the solid was withdrawn for expertise: molybdenum and zirconium are the two major components of the solid, identified as zirconium molybdate. This thesis consisted in the approach of the mechanisms in solution liable to induce precipitate formation. After a bibliographical overview on the chemistry of Mo(VI) in highly acidic solution, this system was studied by absorption spectrophotometry in perchloric medium. The implication of two major forms of Mo(VI) in a dimerization equilibrium was confirmed by this way and by {sup 95}Mo NMR. The principal parameters governing this equilibrium were identified. It is thus shown that the molybdenum dimerization reaction is exothermic. Disturbance of the Mo(VI) system in highly acidic solution by Zr(IV) was also studied. In a restricted experimental field, for which 'conventional' exploitation methodologies had to be adapted to the system, a main complex of stoichiometry 1:1 between Mo(VI) and Zr(IV) was found. The precipitation study of Mo(VI) by Zr(IV) under conditions close to those of the dissolution medium of nuclear spent fuel was undertaken. The main parameters which control precipitation kinetics were identified. The results obtained reveal that precipitation is controlled by a single macroscopic process and therefore can be described by a single equation. The solid obtained is composed of only one phase presenting a Mo:Zr non-stoichiometry when compared to the theoretical formula ZrMo{sub 2}O{sub 7}(OH){sub 2},2H{sub 2}O. At last, on the basis of the research results, a descriptive mechanism of the system is proposed in which intervenes a 1:1 intermediate complex, much more soluble than a probable 2:1 precipitation precursor. (author)

  4. II-VI semiconductor compounds

    CERN Document Server

    1993-01-01

    For condensed matter physicists and electronic engineers, this volume deals with aspects of II-VI semiconductor compounds. Areas covered include devices and applications of II-VI compounds; Co-based II-IV semi-magnetic semiconductors; and electronic structure of strained II-VI superlattices.

  5. Precise positioning of myosin VI on endocytic vesicles in vivo.

    Directory of Open Access Journals (Sweden)

    David Altman

    2007-08-01

    Full Text Available Myosin VI has been studied in both a monomeric and a dimeric form in vitro. Because the functional characteristics of the motor are dramatically different for these two forms, it is important to understand whether myosin VI heavy chains are brought together on endocytic vesicles. We have used fluorescence anisotropy measurements to detect fluorescence resonance energy transfer between identical fluorophores (homoFRET resulting from myosin VI heavy chains being brought into close proximity. We observed that, when associated with clathrin-mediated endocytic vesicles, myosin VI heavy chains are precisely positioned to bring their tail domains in close proximity. Our data show that on endocytic vesicles, myosin VI heavy chains are brought together in an orientation that previous in vitro studies have shown causes dimerization of the motor. Our results are therefore consistent with vesicle-associated myosin VI existing as a processive dimer, capable of its known trafficking function.

  6. A study of low-cost adsorbent materials for removing Cr(VI from aqueous waste effluent Estudio de materiales adsorbentes de bajo costo para remover Cr(VI de efluentes acuosos

    Directory of Open Access Journals (Sweden)

    Castillo Serna Elianna

    2011-05-01

    Full Text Available  

    The present paper shows very high potential for two types of solid (a commercial alumina and material obtained by composting, i.e. matured compost on Cr(VI adsorption/elimination in aqueous solution using a concentration range close to those previously detected in waste-water from Colombian industries. Both had important properties for eliminating Cr(VI, the compost being more important as it represents low-cost material. Optimal conditions for chromium adsorption on alumina and compost were established. Initial Cr(VI alumina concentration was 10 mgL-1, with 100 mL/g volume of solution per adsorbent mass, pH=2.0, 1 hour equilibrium time and 150 rpm stirring. For compost, initial Cr(VI concentration was = 3 mg L-1, 50 mL/g volume of solution per adsorbent mass, pH=2.5, 3 hour equilibrium time and 150 rpm stirring. The experiments showed that compost adsorption properties could be enhanced by adding small quantities of alumina. Compost could thus be chosen as a promising material for use in bioremediation chromium-containing waste water in a management programme for using solid waste in for minimising environmental impact.

     

     

    A FEASIBILITY STUDY ON USING ViSP’S 3D MODEL-BASED TRACKER FOR UAV POSE ESTIMATION IN OUTDOOR ENVIRONMENTS

    Directory of Open Access Journals (Sweden)

    J. Li-Chee-Ming

    2015-08-01

    Full Text Available This paper presents a novel application of the Visual Servoing Platform’s (ViSP for small UAV pose estimation in outdoor environments. Given an initial approximation for the camera position and orientation, or camera pose, ViSP automatically establishes and continuously tracks corresponding features between an image sequence and a 3D wireframe model of the environment. As ViSP has been demonstrated to perform well in small and cluttered indoor environments, this paper explores the application of ViSP for UAV mapping of outdoor landscapes and tracking of large objects (i.e. building models. Our presented experiments demonstrate the data obtainable by the UAV, assess ViSP’s data processing strategies, and evaluate the performance of the tracker.

  7. Characterization of Amoeba proteus myosin VI immunoanalog.

    Science.gov (United States)

    Dominik, Magdalena; Kłopocka, Wanda; Pomorski, Paweł; Kocik, Elzbieta; Redowicz, Maria Jolanta

    2005-07-01

    Amoeba proteus, the highly motile free-living unicellular organism, has been widely used as a model to study cell motility. However, molecular mechanisms underlying its unique locomotion and intracellular actin-based-only trafficking remain poorly understood. A search for myosin motors responsible for vesicular transport in these giant cells resulted in detection of 130-kDa protein interacting with several polyclonal antibodies against different tail regions of human and chicken myosin VI. This protein was binding to actin in the ATP-dependent manner, and immunoprecipitated with anti-myosin VI antibodies. In order to characterize its possible functions in vivo, its cellular distribution and colocalization with actin filaments and dynamin II during migration and pinocytosis were examined. In migrating amoebae, myosin VI immunoanalog localized to vesicular structures, particularly within the perinuclear and sub-plasma membrane areas, and colocalized with dynamin II immunoanalog and actin filaments. The colocalization was even more evident in pinocytotic cells as proteins concentrated within pinocytotic pseudopodia. Moreover, dynamin II and myosin VI immunoanalogs cosedimented with actin filaments, and were found on the same isolated vesicles. Blocking endogenous myosin VI immunoanalog with anti-myosin VI antibodies inhibited the rate of pseudopodia protrusion (about 19% decrease) and uroidal retraction (about 28% decrease) but did not affect cell morphology and the manner of cell migration. Treatment with anti-human dynamin II antibodies led to changes in directionality of amebae migration and affected the rate of only uroidal translocation (about 30% inhibition). These results indicate that myosin VI immunoanalog is expressed in protist Amoeba proteus and may be involved in vesicle translocation and cell locomotion.

  8. Plasmon resonance enhanced photocatalysis under visible light with Au/Cu-TiO2 nanoparticles: Removal Cr (VI) from water as a case of study

    KAUST Repository

    Gondal, M. A.

    2013-12-01

    Gold modified copper doped titania (Au/Cu:TiO2) nanoparticles were synthesized by a modified sol gel method and characterized using XRD, optical and TEM based techniques. The as-prepared material contained anatase phase particles with quasi-spherical morphology, showing enhanced absorption in the visible region and low photoluminescence emission intensity. Photocatalytic reduction of Cr (VI) in aqueous suspension with the Au/Cu:TiO2catalyst under 532 nm laser radiation and a visible broad band lamp source yielded 96% and 45% removal, respectively, without any additives. The enhanced photocatalytic activity can be attributed to the improved plasmonic effect due to gold modification and the expanded visible absorption due to copper doping. Moreover a comparative study of the material properties and catalytic activity of TiO2, Cu-TiO2and Au/Cu-TiO2 was carried out. © 2013 by American Scientific Publishers.

  9. X-ray diffraction study of the molecular propolis films deposited from an alcohol solution onto the cleavage surfaces of layered V2VI3 compounds

    Science.gov (United States)

    Drapak, S. I.; Gavrylyuk, S. V.; Kaminskii, V. M.; Kovalyuk, Z. D.

    2008-09-01

    The structures of the molecular propolis films deposited from an alcohol solution on the (0001) cleavage surface of layered bismuth selenide and telluride are studied by X-ray diffraction. Despite the chemical interaction between the semiconductor substrates and the organic-substance components, the molecular structural ordering of the propolis films is shown to be identical to that in the films of this substance on the surface of amorphous glass substrates. The chemical and deformation interaction between the organic substance and the layered V2VI3 compounds is found to result in the formation of an organic-inorganic sandwich nanostructure at a distance of ˜0.3 μm from the layered crystal-propolis film interface.

  10. Study on the binding interaction of chromium(VI) with humic acid using UV-vis, fluorescence spectroscopy and molecular modeling

    Science.gov (United States)

    Gu, Yun-Lan; Yin, Ming-Xing; Zhang, Hong-Mei; Wang, Yan-Qing; Shi, Jing-hua

    2015-02-01

    In this report, the binding interaction of chromium(VI), as Cr2O72-, with humic acid was studied by using UV-visible absorption, fluorescence spectroscopy, and molecular modeling method. The fluorescence spectral data indicated that the binding interaction existed between Cr2O72- and humic acid and the order of magnitude of binding constants were 103. The rise in temperature caused a decrease in the values of the binding constant of humic acid with Cr2O72-. Thermodynamic analysis presented that multi-intermolecular forces including hydrogen bonding, hydrophobic, and electrostatic forces were involved in the binding process at pH 6.5. The spectral data also indicated that Cr2O72- affected the aromatic ring structures in humic acid. Furthermore, the molecular modeling analysis indicated that a lot of reactive groups and binding cavities in HA played a key role in its binding with Cr2O72-.

  11. Immunogenicity of a new Salmonella Typhi Vi polysaccharide vaccine--vax-TyVi--in Cuban school children and teenagers.

    Science.gov (United States)

    Azze, Rolando Felipe Ochoa; Rodríguez, Juan Carlos Martínez; Iniesta, Mónica Ginebra; Marchena, Xenia Rosa Ferriol; Alfonso, Vivian María Rodríguez; Padrón, Franklin Tomás Sotolongo

    2003-06-20

    A randomized, controlled, double blind study was carried out in Cuban children and teenagers aged 9-13 years to evaluate the immunogenicity of vax-TyVi-Salmonella Typhi Vi polysaccharide vaccine-with respect control vaccines. Serum samples were taken before and 21 days after the immunization, and ELISA was used for the determination of antibodies to Vi polysaccharide. Subjects who received vax-TyVi and TYPHIM Vi (Pasteur-Mérieux) showed seroconversion rates of 85.61 and 78.36%, respectively. The geometric mean titer (GMT) values for Vi antibodies induced after vaccination were 6.27 microg/ml (5.40-7.38 microg/ml) and 5.97 microg/ml (5.01-7.10 microg/ml), respectively. In contrast, subjects receiving the tetanus toxoid vaccine showed 0% seroconversion.

  12. Study of the thermodynamics of chromium(III) and chromium(VI) binding to iron(II/III)oxide or magnetite or ferrite and magnanese(II) iron (III) oxide or jacobsite or manganese ferrite nanoparticles.

    Science.gov (United States)

    Luther, Steven; Brogfeld, Nathan; Kim, Jisoo; Parsons, J G

    2013-06-15

    Removal of chromium(III) or (VI) from aqueous solution was achieved using Fe3O4, and MnFe2O4 nanomaterials. The nanomaterials were synthesized using a precipitation method and characterized using XRD. The size of the nanomaterials was determined to be 22.4±0.9 nm (Fe3O4) and 15.5±0.5 nm (MnFe2O4). The optimal binding pH for chromium(III) and chromium(VI) were pH 6 and pH 3. Isotherm studies were performed, under light and dark conditions, to determine the capacity of the nanomaterials. The capacities for the light studies with MnFe2O4 and Fe3O4 were determined to be 7.189 and 10.63 mg/g, respectively, for chromium(III). The capacities for the light studies with MnFe2O4 and Fe3O4 were 3.21 and 3.46 mg/g, respectively, for chromium(VI). Under dark reaction conditions the binding of chromium(III) to the MnFe2O4 and Fe3O4 nanomaterials were 5.74 and 15.9 mg/g, respectively. The binding capacity for the binding of chromium(VI) to MnFe2O4 and Fe3O4 under dark reaction conditions were 3.87 and 8.54 mg/g, respectively. The thermodynamics for the reactions showed negative ΔG values, and positive ΔH values. The ΔS values were positive for the binding of chromium(III) and for chromium(VI) binding under dark reaction conditions. The ΔS values for chromium(VI) binding under the light reaction conditions were determined to be negative.

  13. Singular Instantons and Painlevé VI

    Science.gov (United States)

    Muñiz Manasliski, Richard

    2016-06-01

    We consider a two parameter family of instantons, which is studied in [Sadun L., Comm. Math. Phys. 163 (1994), 257-291], invariant under the irreducible action of SU_2 on S^4, but which are not globally defined. We will see that these instantons produce solutions to a one parameter family of Painlevé VI equations (P_VI}) and we will give an explicit expression of the map between instantons and solutions to P_{VI}. The solutions are algebraic only for that values of the parameters which correspond to the instantons that can be extended to all of S^4. This work is a generalization of [Muñiz Manasliski R., Contemp. Math., Vol. 434, Amer. Math. Soc., Providence, RI, 2007, 215-222] and [Muñiz Manasliski R., J. Geom. Phys. 59 (2009), 1036-1047, arXiv:1602.07221], where instantons without singularities are studied.

  14. Study of the characteristic response of the pressure control system for the design parameters of the new turbine control system, MARK VI, in Cofrentes Nuclear Power Plant; Resultados del estudio de la respuesta caracteristica del sistema de control de presion para el Proyecto OCP-4300 Nuevo Sistema de Control de Turbina MARK VI en la C.N. Cofrentes

    Energy Technology Data Exchange (ETDEWEB)

    Palomo anaya, M. J.; Ruiz Bueno, G.; Mora, J. A.; Vaquer, J. I.; Bucho, L.; Lopez, B.

    2010-07-01

    This paper presents the results of the study of the characteristic response of the ancient Pressure and Turbine Control System for the OCP-4300 Project in the Cofrentes Nuclear Power Plant, made by Titania Servicios Tecnologicos in collaboration with the Institute for Industrial, Radiophysical and Environmental Safety. This work was done as one of the preliminary work necessary for replacing the old control system by Mark VI.

  15. An interdisciplinary knowledge translation intervention in long-term care: Study protocol for the vitamin D and osteoporosis study (ViDOS pilot cluster randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Kennedy Courtney C

    2012-05-01

    Full Text Available Abstract Background Knowledge translation (KT research in long-term care (LTC is still in its early stages. This protocol describes the evaluation of a multifaceted, interdisciplinary KT intervention aimed at integrating evidence-based osteoporosis and fracture prevention strategies into LTC care processes. Methods and design The Vitamin D and Osteoporosis Study (ViDOS is underway in 40 LTC homes (n = 19 intervention, n = 21 control across Ontario, Canada. The primary objectives of this study are to assess the feasibility of delivering the KT intervention, and clinically, to increase the percent of LTC residents prescribed ≥800 IU of vitamin D daily. Eligibility criteria are LTC homes that are serviced by our partner pharmacy provider and have more than one prescribing physician. The target audience within each LTC home is the Professional Advisory Committee (PAC, an interdisciplinary team who meets quarterly. The key elements of the intervention are three interactive educational sessions led by an expert opinion leader, action planning using a quality improvement cycle, audit and feedback reports, nominated internal champions, and reminders/point-of-care tools. Control homes do not receive any intervention, however both intervention and control homes received educational materials as part of the Ontario Osteoporosis Strategy. Primary outcomes are feasibility measures (recruitment, retention, attendance at educational sessions, action plan items identified and initiated, internal champions identified, performance reports provided and reviewed, and vitamin D (≥800 IU/daily prescribing at 6 and 12 months. Secondary outcomes include the proportion of residents prescribed calcium supplements and osteoporosis medications, and falls and fractures. Qualitative methods will examine the experience of the LTC team with the KT intervention. Homes are centrally randomized to intervention and control groups in blocks of variable size using

  16. Extractive removal of chromium (VI) from industrial waste solution.

    Science.gov (United States)

    Agrawal, Archana; Pal, Chandana; Sahu, K K

    2008-11-30

    Extractive removal of Cr (VI) was carried out from chloride solutions using cyanex 923 mixed with kerosene. The efficiency of this extractant was studied under various experimental conditions, such as concentration of different mineral acids in the aqueous phase, concentration of cyanex 923 and Cr (VI) present in the initial aqueous feed, temperature and time of extraction, organic to aqueous (O/A) phase ratio. Percentage Cr (VI) extraction decreases with the increase in temperature at varying concentration of cyanex 923. The interference of the impurities usually associated with Cr (VI) such as Cr (III), Cu, Ni, Fe (II), Zn, Chloride and sulphate, etc., were examined under the optimized conditions and only Zn was found to interfere. Under the optimum experimental conditions 98.6-99.9% of Cr (VI) was extracted in 3-5 min at O/A of 2 with the initial feed concentration of 1g/L of Cr (VI). The extracted Cr (VI) was quantitatively stripped with 1M NaOH and the organic phase obtained after the stripping of Cr (VI) was washed with dilute HCl solution to neutralize any NaOH trapped/adhered to the solvent and then with distilled water. This regenerated solvent was reused in succeeding extraction of chromium (VI). Finally a few experiments were performed with the synthetic effluent from an electroplating industry.

  17. Test results of Salmonella typing by the NRLs-Salmonella in the Member States of the EU and the EnterNet Laboratories - Collaborative study VI on typing of Salmonella

    NARCIS (Netherlands)

    Korver H; Raes M; Maas HME; Ward LR; Wannet WJB; Henken AM; PHLS-Colindale/London; MGB; LIS

    2002-01-01

    Test results of Salmonella sero- and phage typing and antimicrobial susceptibility testing by the National Reference Laboratories for Salmonella in the Member States of the European Union and the EnterNet Laboratories: Collaborative study VI (2001) for Salmonella. The sixth collaborative typing stud

  18. Dicaesium tetrachloridodioxidoplutonate(VI

    Directory of Open Access Journals (Sweden)

    Marianne P. Wilkerson

    2008-01-01

    Full Text Available The anion of the title complex, Cs2[PuCl4O2], adopts a pseudo-octahedral geometry (2/m crystallographic site symmetry with two plutonyl oxide ligands in axial sites and four chloride ligands occupying the equatorial plane. Charge balance is maintained by two caesium cations per tetrachloridodioxidoplutonate(VI anion. Principal bond lengths include Pu—O = 1.752 (3 Å and Pu—Cl = 2.6648 (8 Å.

  19. Vi I typing phage for generalized transduction of Salmonella typhi.

    OpenAIRE

    Cerquetti, M C; Hooke, A M

    1993-01-01

    Salmonella typhi Vi typing phages were used to transduce temperature-sensitive (Ts) mutants of Salmonella typhi. Antibiotic resistance and Ts+ markers were transduced at high frequency (> 10(-4) per virulent phage). Several markers were cotransduced by phage Vi I, suggesting that it may be useful for mapping studies of the S. typhi genome.

  1. Study of the adsorption of Cr(VI) by tannic acid immobilised powdered activated carbon from micro-polluted water in the presence of dissolved humic acid.

    Science.gov (United States)

    Gong, Xujin; Li, Weiguang; Wang, Ke; Hu, Jinhua

    2013-08-01

    The adsorption of Cr(VI) (0.500 mg/L) onto food-grade tannic-acid immobilised powdered activated carbon (TA-PAC) in the presence of dissolved humic acid (DHA) was investigated at 280 K as a function of pH, along with the adsorption capacities and the adsorption isotherms for chromium ions. The results showed that the presence of DHA improved the adsorption capacities of Cr(VI) and its reduction product (Cr(III)) over a wide pH range (4.0-8.0). The main mechanism for metal-DHA complexation in the Cr(VI) system was the reduction of Cr(VI) followed by complexation between Cr(III) and DHA. The Freundlich isotherms yielded the best fits to all data (R(2)=0.9951, qm=5.639 mg/g) in the presence of DHA. The adsorption mechanisms of Cr(VI) onto TA-PAC in the presence of DHA were summarized into three categories: (i) binding by anion adsorption, (ii) Cr(VI) reduction followed by Cr(III) adsorption, and (iii) adsorption of Cr(III)-DHA complexes.

  2. Contribution of extracellular polymeric substances from Shewanella sp. HRCR-1 biofilms to U(VI) immobilization.

    Science.gov (United States)

    Cao, Bin; Ahmed, Bulbul; Kennedy, David W; Wang, Zheming; Shi, Liang; Marshall, Matthew J; Fredrickson, Jim K; Isern, Nancy G; Majors, Paul D; Beyenal, Haluk

    2011-07-01

    The goal of this study was to quantify the contribution of extracellular polymeric substances (EPS) to U(VI) immobilization by Shewanella sp. HRCR-1. Through comparison of U(VI) immobilization using cells with bound EPS (bEPS) and cells with minimal EPS, we show that (i) bEPS from Shewanella sp. HRCR-1 biofilms contribute significantly to U(VI) immobilization, especially at low initial U(VI) concentrations, through both sorption and reduction; (ii) bEPS can be considered a functional extension of the cells for U(VI) immobilization and they likely play more important roles at lower initial U(VI) concentrations; and (iii) the U(VI) reduction efficiency is dependent upon the initial U(VI) concentration and decreases at lower concentrations. To quantify the relative contributions of sorption and reduction to U(VI) immobilization by EPS fractions, we isolated loosely associated EPS (laEPS) and bEPS from Shewanella sp. HRCR-1 biofilms grown in a hollow fiber membrane biofilm reactor and tested their reactivity with U(VI). We found that, when reduced, the isolated cell-free EPS fractions could reduce U(VI). Polysaccharides in the EPS likely contributed to U(VI) sorption and dominated the reactivity of laEPS, while redox active components (e.g., outer membrane c-type cytochromes), especially in bEPS, possibly facilitated U(VI) reduction.

  3. Implementing a Knowledge Translation Intervention in Long-Term Care: Feasibility Results From the Vitamin D and Osteoporosis Study (ViDOS)

    Science.gov (United States)

    Kennedy, Courtney C.; Thabane, Lehana; Ioannidis, George; Adachi, Jonathan D.; Papaioannou, Alexandra

    2016-01-01

    Objectives To evaluate the feasibility of implementing an interdisciplinary, multifaceted knowledge translation intervention within long-term care (LTC) and to identify any challenges that should be considered in designing future studies. Design Cluster randomized controlled trial. Setting Forty LTC homes across the province of Ontario, Canada. Participants LTC teams composed of physicians, nurses, pharmacists, and other staff. Measurements Cluster-level feasibility measures, including recruitment, retention, data completion, and participation in the intervention. A process evaluation was completed by directors of care indicating which process/policy changes had been implemented. Results Recruitment and retention rates were 22% and 63%, respectively. Good fidelity with the intervention was achieved, including attendance at educational meetings. After ViDOS, 7 process indicators were being newly implemented by more than 50% of active intervention homes. Conclusion Despite recruitment and retention challenges, the multifaceted intervention produced a number of policy/process changes and had good intervention fidelity. This study is registered at ClinicalTrials.gov NCT01398527. PMID:24953541

  4. New insight of coordination and extraction of uranium(VI) with N-donating ligands in room temperature ionic liquids: N,N'-diethyl-N,N'-ditolyldipicolinamide as a case study.

    Science.gov (United States)

    Yuan, Li-Yong; Sun, Man; Mei, Lei; Wang, Lin; Zheng, Li-Rong; Gao, Zeng-Qiang; Zhang, Jing; Zhao, Yu-Liang; Chai, Zhi-Fang; Shi, Wei-Qun

    2015-02-16

    Room temperature ionic liquids (RTILs) represent a recent new class of solvents applied in liquid/liquid extraction based nuclear fuel reprocessing, whereas the related coordination chemistry and detailed extraction processes are still not well understood and remain of deep fundamental interest. The work herein provides a new insight of coordination and extraction of uranium(VI) with N-donating ligands, e.g., N,N'-diethyl-N,N'-ditolyldipicolinamide (EtpTDPA), in commonly used RTILs. Exploration of the extraction mechanism, speciation analyses of the extracted U(VI), and crystallographic studies of the interactions of EtpTDPA with U(VI) were performed, including the first structurally characterized UO2(EtpTDPA)2(NTf2) and UO2(EtpTDPA)2(PF6)2 compounds and a first case of crystallographic differentiation between the extracted U(VI) complexes in RTILs and in molecular solvents. It was found that in RTILs two EtpTDPA molecules coordinate with one U(VI) ion through the carbonyl and pyridine nitrogen moieties, while NTf2(-) and PF6(-) act as counterions. The absence of NO3(-) in the complexes is coincident with a cation-exchange extraction. In contrast, both the extracted species and extraction mechanisms are greatly different in dichloromethane, in which UO2(2+) coordinates in a neutral complex form with one EtpTDPA molecule and two NO3(-) cations. In addition, the complex formation in RTILs is independent of the cation exchange since incorporating UO2(NO3)2, EtpTDPA, and LiNTf2 or KPF6 in a solution also produces the same complex as that in RTILs, revealing the important roles of weakly coordinating anions on the coordination chemistry between U(VI) and EtpTDPA. These findings suggest that cation-exchange extraction mode for ILs-based extraction system probably originates from the supply of weakly coordinating anions from RTILs. Thus the coordination of uranium(VI) with extractants as well as the cation-exchange extraction mode may be potentially changed by varying the

  5. Econophys-Kolkata VI Conference

    CERN Document Server

    Chakrabarti, Bikas; Chakraborti, Anirban; Ghosh, Asim

    2013-01-01

    The primary goal of the book is to present the ideas and research findings of active researchers such as physicists, economists, mathematicians and financial engineers working in the field of “Econophysics,” who have undertaken the task of modeling and analyzing systemic risk, network dynamics and other topics. Of primary interest in these studies is the aspect of systemic risk, which has long been identified as a potential scenario in which financial institutions trigger a dangerous contagion mechanism, spreading from the financial economy to the real economy. This type of risk, long confined to the monetary market, has spread considerably in the recent past, culminating in the subprime crisis of 2008. As such, understanding and controlling systemic risk has become an extremely important societal and economic challenge. The Econophys-Kolkata VI conference proceedings are dedicated to addressing a number of key issues involved. Several leading researchers in these fields report on their recent work and al...

  6. Persistence of antibody titres three years after vaccination with Vi polysaccharide vaccine against typhoid fever.

    Science.gov (United States)

    Tacket, C O; Levine, M M; Robbins, J B

    1988-08-01

    After a single injection of purified Vi polysaccharide vaccine against typhoid fever, serum titres were followed in student volunteers by passive haemagglutination assay and by radioimmunoassay. Elevated Vi antibody titres were still present after 36 months. This preliminary study should be followed by further investigations on the extent and duration of protection provided by Vi vaccine, and on volunteers in endemic areas.

  7. Nuclear magnetic resonance studies on the pKa values and interaction of ionizable groups in bromelain inhibitor VI from pineapple stem.

    Science.gov (United States)

    Hatano, Ken-ichi; Kojima, Masaki; Tanokura, Masaru; Takahashi, Kenji

    2003-01-01

    Bromelain inhibitor VI (BI-VI), a cysteine proteinase inhibitor from pineapple stem, is a unique double-chain molecule composed of two distinct domains A and B. In order to clarify the molecular mechanism of the proteinase-inhibitor interaction, we investigated the electrostatic properties of this inhibitor. The inhibitory activity toward bromelain was revealed to be maximal at pH 3-4 and the gross conformation to be stable over a wide range of pH. Based on these results, pH titration experiments were performed on the proton resonances of BI-VI in the pH range of 1.5-9.9, and pKa values (pKexp) were determined for all carboxyl groups and alpha-amino groups. The pKexp were also compared with theoretical values calculated from the NMR-derived structures of BI-VI. The electrostatic surface potential map constructed using the pKexp values revealed that BI-VI possesses continuous negatively charged and scattered positively charged regions on the molecular surface and both regions appear to serve for docking properly with a basic target enzyme. Furthermore, it was suggested that the ionic interaction of the inhibitor with the target enzyme is primarily important for the inhibition, which seems to involve some carboxyl groups in the inhibitor and a thiol group in the proteinase.

  8. Protostars and Planets VI

    Science.gov (United States)

    Beuther, Henrik; Klessen, Ralf S.; Dullemond, Cornelis P.; Henning, Thomas

    The Protostars and Planets book and conference series has been a long-standing tradition that commenced with the first meeting led by Tom Gehrels and held in Tucson, Arizona, in 1978. The goal then, as it still is today, was to bridge the gap between the fields of star and planet formation as well as the investigation of planetary systems and planets. As Tom Gehrels stated in the preface to the first Protostars and Planets book, "Cross-fertilization of information and understanding is bound to occur when investigators who are familiar with the stellar and interstellar phases meet with those who study the early phases of solar system formation." The central goal remained the same for the subsequent editions of the books and conferences Protostars and Planets II in 1984, Protostars and Planets III in 1990, Protostars and Planets IV in 1998, and Protostars and Planets V in 2005, but has now been greatly expanded by the flood of new discoveries in the field of exoplanet science. The original concept of the Protostars and Planets series also formed the basis for the sixth conference in the series, which took place on July 15-20, 2013. It was held for the first time outside of the United States in the bustling university town of Heidelberg, Germany. The meeting attracted 852 participants from 32 countries, and was centered around 38 review talks and more than 600 posters. The review talks were expanded to form the 38 chapters of this book, written by a total of 250 contributing authors. This Protostars and Planets volume reflects the current state-of-the-art in star and planet formation, and tightly connects the fields with each other. It is structured into four sections covering key aspects of molecular cloud and star formation, disk formation and evolution, planetary systems, and astrophysical conditions for life. All poster presentations from the conference can be found at www.ppvi.org. In the eight years that have passed since the fifth conference and book in the

  9. Social Representations of the Artisan Work: Study of Case of an Association of Craftsmen in Viçosa, Minas Gerais – Brazil

    Directory of Open Access Journals (Sweden)

    Alair Ferreira de Freitas

    2010-07-01

    Full Text Available This article aims to analyze the social representations of small-scale artisans working for associated Association of Artisans and food producers Homemade of Viçosa, Minas Gerais State-Brazil (Adapac. To this end we have tried to identify and analyse the trajectory of the craftsmen and the reasons for becoming involved with crafts and renditions of the craft for craftsmen linked to this Association. The methodological strategy adopted for the research consisted in case study. As an instrument of data collection, were used to survey participant and application of semi-structured interviews. The method of "content analysis" was used in the Organization and analysis of data. For discussion of the results were defined two categories: (i motivations for the craft and (ii representations of the craft. The results show that this type of work associates itself as the premier opportunity to occupation and income generation found by some members and another as vocation and manual skills. For women the social representations of craft relate the condition of personal satisfaction and possibility of reconciliation with the domestic activities, while for men representations indicate the enhancement of the economic dimension of the craft, distinguishing it from domestic activities.

  10. A Monte Carlo Study of Flux Ratios of Raman Scattered O vi Features at 6825 and 7082 Å in Symbiotic Stars

    Science.gov (United States)

    Lee, Young-Min; Lee, Dae-Sub; Chang, Seok-Jun; Heo, Jeong-Eun; Lee, Hee-Won; Hwang, Narae; Park, Byeong-Gon; Lee, Ho-Gyu

    2016-12-01

    Symbiotic stars are regarded as wide binary systems consisting of a hot white dwarf and a mass losing giant. They exhibit unique spectral features at 6825 and 7082 Å, which are formed via Raman scattering of O vi λλ 1032 and 1038 with atomic hydrogen. We adopt a Monte Carlo technique to generate the same number of O vi λ1032 and λ1038 line photons and compute the flux ratio F(6825)/F(7082) of these Raman scattered O vi features formed in neutral regions with a simple geometric shape as a function of H i column density N H i . In cylindrical and spherical neutral regions with the O vi source embedded inside, the flux ratio F(6825)/F(7082) shows an overall decrease from 3 to 1 as N H i increases in the range {10}22{--24} {{cm}}-2. In cases of slab geometry and other geometries with the O vi source outside the H i region, Rayleigh escape operates to lower the flux ratio considerably. For moderate values of {N}{{H}{{I}}}˜ {10}23 {{cm}}-2 the flux ratio behaves in a complicated way to exhibit a broad bump with a peak value of 3.5 in the case of a sphere geometry. We find that the ratio of Raman conversion efficiencies of O vi λλ 1032, 1038 ranges from 0.8 to 3.5. Our high resolution spectra of “D” type HM Sge and “S” type AG Dra obtained with the Canada-France-Hawaii Telescope show that the flux ratio F(6825)/F(7082) of AG Dra is significantly smaller than that of HM Sge, implying that “S” type symbiotics are characterized by higher N H i than “D” type symbiotics.

  11. Electrochemical alkaline Fe(VI) water purification and remediation.

    Science.gov (United States)

    Licht, Stuart; Yu, Xingwen

    2005-10-15

    Fe(VI) is an unusual and strongly oxidizing form of iron, which provides a potentially less hazardous water-purifying agent than chlorine. A novel on-line electrochemical Fe(VI) water purification methodology is introduced. Fe(VI) addition had been a barrier to its effective use in water remediation, because solid Fe(VI) salts require complex (costly) syntheses steps and solutions of Fe(VI) decompose. Online electrochemical Fe(VI) water purification avoids these limitations, in which Fe(VI) is directly prepared in solution from an iron anode as the FeO42- ion, and is added to the contaminant stream. Added FeO42- decomposes, by oxidizing a wide range of water contaminants including sulfides (demonstrated in this study) and other sulfur-containing compounds, cyanides (demonstrated in this study), arsenic (demonstrated in this study), ammonia and other nitrogen-containing compounds (previously demonstrated), a wide range of organics (phenol demonstrated in this study), algae, and viruses (each previously demonstrated).

  12. Small angle neutron scattering study of U(VI) third phase formation in HNO3/DHDECMP–-dodecane system

    Indian Academy of Sciences (India)

    K V Lohithakshan; V K Aswal; S K Aggarwal

    2008-11-01

    Small angle neutron scattering studies (SANS) were carried out to understand the formation of third phase in DHDECMP–dodecane–UO2(NO3)2/HNO3 system. It was observed that third phase formation takes place due to the formation of UO2(NO3)2. DHDECMP reverse micelles in the dodecane phase. SANS data obtained were interpreted with particle interaction model using Baxter sticky spheres model.

  13. Studies on phycobiliproteins in Algae. VI. Light-harvesting phycobiliprotein pigments in some Rhodophyta from the Adriatic Sea

    Directory of Open Access Journals (Sweden)

    Bazyli Czeczuga

    2014-02-01

    Full Text Available The phycobiliprotein content in 5 species of red algae from the coast of the Adriatic Sea' was studied by chromatography on Sephadex G-100. The phycobiliproteins, R-phycoerythrin, C-phycocyanin and allophycocyanin were identified. The total content of phycobiliproteins ranged from 0.152 (Phyllophora nervosa to 1.874 mg•g-1 dry wt. (Plocamium cartilagineum. The dominant phycobiliproteins were found to belong to the phycocyanin group, this resulting from complementary chromatic adaptation.

  14. Oxidising alternative species to chromium VI in zinc-galvanised steel surface treatment. Part 2. An electrochemical study

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, E. [Inst. Nacional de Engenharia e Tecnologia Industrial, Lisbon (Portugal); Fedrizzi, L. [Material Engineering Department, University of Trento, Trento (Italy); Diamantinio, T.C. [Inst. Nacional de Engenharia e Tecnologia Industrial, Lisbon (Portugal)]|[Instituto do Ambiente e Vida, Departamento de Zoologia, Universidade de Coimbra, Coimbra (Portugal)

    1998-06-05

    In the first part of this work, the authors present the main results and conclusions of a morphological and chemical study carried out on zinc conversion layers (ZCLs) obtained with oxidising alternative passivation baths, that includes molybdates, permanganates, vanadates and tungstates. A good chromate-based bath was used as reference. In this second part of the work, the authors present the main results obtained on selected zinc conversion layers (ZCLs), using a.c. electrochemical impedance spectroscopy (EIS). The results obtained were correlated with the morphological and chemical data obtained with the same ZCLs in the first part of this work. Finally, it is concluded that the alternative ZCLs studied, does not seem to be as efficient as that obtained with a chromate-based passivation bath used as reference. It is believed that a better understanding of the mechanisms involved in the ZCL`s formation, can be useful for studying, in the very near future, possible synergetic effects between molybdates and other chemical species. (orig.) 24 refs.

  15. Contribution of Extracellular Polymeric Substances from Shewanella sp. HRCR-1 Biofilms to U(VI) Immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Bin; Ahmed, B.; Kennedy, David W.; Wang, Zheming; Shi, Liang; Marshall, Matthew J.; Fredrickson, Jim K.; Isern, Nancy G.; Majors, Paul D.; Beyenal, Haluk

    2011-06-05

    The goal of this study was to quantify the contribution of extracellular polymeric substances (EPS) in U(VI) immobilization by Shewanella sp. HRCR-1. Through comparison of U(VI) immobilization using cells with bound EPS (bEPS) and cells without EPS, we showed that i) bEPS from Shewanella sp. HRCR-1 biofilms contributed significantly to U(VI) immobilization, especially at low initial U(VI) concentrations, through both sorption and reduction; ii) bEPS could be considered as a functional extension of the cells for U(VI) immobilization and they likely play more important roles at initial U(VI) concentrations; and iii) U(VI) reduction efficiency was found to be dependent upon initial U(VI) concentration and the efficiency decreased at lower concentrations. To quantify relative contribution of sorption and reduction in U(VI) immobilization by EPS fractions, we isolated loosely associated EPS (laEPS) and bEPS from Shewanella sp. HRCR-1 biofilms grown in a hollow fiber membrane biofilm reactor and tested their reactivity with U(V). We found that, when in reduced form, the isolated cell-free EPS fractions could reduce U(VI). Polysaccharides in the EPS likely contributed to U(VI) sorption and dominated reactivity of laEPS while redox active components (e.g., outer membrane c-type cytochromes), especially in bEPS, might facilitate U(VI) reduction.

  16. ViFiLite Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ViFiLite is a wireless infrastructure that utilizes the advantages of a V-band technology in supporting data gathering for structural health monitoring as well as...

  17. Social vulnerability assessment using spatial multi-criteria analysis (SEVI model and the Social Vulnerability Index (SoVI model – a case study for Bucharest, Romania

    Directory of Open Access Journals (Sweden)

    I. Armaș

    2013-06-01

    Full Text Available In recent decades, the development of vulnerability frameworks has enlarged the research in the natural hazards field. Despite progress in developing the vulnerability studies, there is more to investigate regarding the quantitative approach and clarification of the conceptual explanation of the social component. At the same time, some disaster-prone areas register limited attention. Among these, Romania's capital city, Bucharest, is the most earthquake-prone capital in Europe and the tenth in the world. The location is used to assess two multi-criteria methods for aggregating complex indicators: the social vulnerability index (SoVI model and the spatial multi-criteria social vulnerability index (SEVI model. Using the data of the 2002 census we reduce the indicators through a factor analytical approach to create the indices and examine if they bear any resemblance to the known vulnerability of Bucharest city through an exploratory spatial data analysis (ESDA. This is a critical issue that may provide better understanding of the social vulnerability in the city and appropriate information for authorities and stakeholders to consider in their decision making. The study emphasizes that social vulnerability is an urban process that increased in a post-communist Bucharest, raising the concern that the population at risk lacks the capacity to cope with disasters. The assessment of the indices indicates a significant and similar clustering pattern of the census administrative units, with an overlap between the clustering areas affected by high social vulnerability. Our proposed SEVI model suggests adjustment sensitivity, useful in the expert-opinion accuracy.

  18. Social vulnerability assessment using spatial multi-criteria analysis (SEVI model) and the Social Vulnerability Index (SoVI model) - a case study for Bucharest, Romania

    Science.gov (United States)

    Armaş, I.; Gavriş, A.

    2013-06-01

    In recent decades, the development of vulnerability frameworks has enlarged the research in the natural hazards field. Despite progress in developing the vulnerability studies, there is more to investigate regarding the quantitative approach and clarification of the conceptual explanation of the social component. At the same time, some disaster-prone areas register limited attention. Among these, Romania's capital city, Bucharest, is the most earthquake-prone capital in Europe and the tenth in the world. The location is used to assess two multi-criteria methods for aggregating complex indicators: the social vulnerability index (SoVI model) and the spatial multi-criteria social vulnerability index (SEVI model). Using the data of the 2002 census we reduce the indicators through a factor analytical approach to create the indices and examine if they bear any resemblance to the known vulnerability of Bucharest city through an exploratory spatial data analysis (ESDA). This is a critical issue that may provide better understanding of the social vulnerability in the city and appropriate information for authorities and stakeholders to consider in their decision making. The study emphasizes that social vulnerability is an urban process that increased in a post-communist Bucharest, raising the concern that the population at risk lacks the capacity to cope with disasters. The assessment of the indices indicates a significant and similar clustering pattern of the census administrative units, with an overlap between the clustering areas affected by high social vulnerability. Our proposed SEVI model suggests adjustment sensitivity, useful in the expert-opinion accuracy.

  19. Mechanism of uranium(VI) uptake by Saccharomyces cerevisiae under environmentally relevant conditions: Batch, HRTEM, and FTIR studies

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xia, E-mail: lux2009@lzu.edu.cn; Zhou, Xiao-jiao; Wang, Tie-shan, E-mail: tswang@lzu.edu.cn

    2013-11-15

    Highlights: • Equilibrium reaches very rapid within 15 min. • pH shift towards neutral indicates release of hydroxyl ions. • High ionic strength inhabits biosorption capacity. • Uptake capacity of heat-killed cells is an order of magnitude higher than live one. • Electrostatic interaction, precipitation, and complexation are the main mechanisms. -- Abstract: Biosorption is of significance for the safety evaluation of high-level nuclear wastes repositories and remediation of radioactive contamination places. Quantitive study and structural characterization of uranium uptake by both live and heat-killed Saccharomyces cerevisiae at environmentally relevant uranium concentration and with different ionic strengths were carried out. Kinetic investigation showed the equilibrium reached within 15 min. In equilibrium studies, pH shift towards neutral indicated release of hydroxyl ions. pH was the most important factor, which partly affected electrostatic interaction between uranyl ions and S. cerevisiae surface. The high ionic strength inhibited biosorption capacity, which can be explained by a competitive reaction between sodium ions and uranyl ions. Heat killing process significantly enhanced biosorption capacity, showing an order of magnitude higher than that of live cells. High resolution transmission electron microscopy (HRTEM) coupled with energy dispersive X-ray (EDX) showed needle-like uranium-phosphate precipitation formed on the cell walls for both live and heat-killed cells. Besides, dark-field micrographs displayed considerable similar uranium-phosphate precipitation presented outside the heat-killed cells. The phosphate released during heat-killing process. FTIR illustrated function groups hydroxyl, carboxyl, phosphate, and amino groups played important role in complexation with uranium.

  20. A luminescence line-narrowing spectroscopic study of the uranium(VI) interaction with cementitious materials and titanium dioxide.

    Science.gov (United States)

    Tits, Jan; Walther, Clemens; Stumpf, Thorsten; Macé, Nathalie; Wieland, Erich

    2015-01-21

    Non-selective luminescence spectroscopy and luminescence line-narrowing spectroscopy were used to study the retention of UO2(2+) on titanium dioxide (TiO2), synthetic calcium silicate hydrate (C-S-H) phases and hardened cement paste (HCP). Non-selective luminescence spectra showed strong inhomogeneous line broadening resulting from a strongly disordered UO2(2+) bonding environment. This problem was largely overcome by using luminescence line-narrowing spectroscopy. This technique allowed unambiguous identification of three different types of UO2(2+) sorbed species on C-S-H phases and HCP. Comparison with spectra of UO2(2+) sorbed onto TiO2 further allowed these species to be assigned to a surface complex, an incorporated species and an uranate-like surface precipitate. This information provides the basis for mechanistic models describing the UO2(2+) sorption onto C-S-H phases and HCP and the assessment of the mobility of this radionuclide in a deep geological repository for low and intermediate level radioactive waste (L/ILW) as this kind of waste is often solidified with cement prior to storage.

  1. Effect of Phosphate on U(VI) Sorption to Montmorillonite: Ternary Complexation and Precipitation Barriers

    Energy Technology Data Exchange (ETDEWEB)

    Troyer, Lyndsay D.; Maillot, Fabien; Wang, Zheming; Wang, Zimeng; Mehta, Vrajesh; Giammar, Daniel; Catalano, Jeffrey G.

    2016-02-15

    reveals that ternary complexation may occur without a macroscopic signature, which is attributed to phosphate not appreciably binding to smectite in the absence of U(VI), with U(VI) surface complexes serving as the sole reactive surface sites for phosphate. This study shows that phosphate does not enhance U(VI) adsorption to smectite clay minerals, unlike oxide phases, and that a barrier to homogeneous nucleation of U(VI) phosphates was not affected by the presence of the smectite surface

  2. Effect of phosphate on U(VI) sorption to montmorillonite: Ternary complexation and precipitation barriers

    Science.gov (United States)

    Troyer, Lyndsay D.; Maillot, Fabien; Wang, Zheming; Wang, Zimeng; Mehta, Vrajesh S.; Giammar, Daniel E.; Catalano, Jeffrey G.

    2016-02-01

    reveals that ternary complexation may occur without a macroscopic signature, which is attributed to phosphate not appreciably binding to smectite in the absence of U(VI), with U(VI) surface complexes serving as the sole reactive surface sites for phosphate. This study shows that phosphate does not enhance U(VI) adsorption to smectite clay minerals, unlike oxide phases, and that a barrier to homogeneous nucleation of U(VI) phosphates was not affected by the presence of the smectite surface.

  3. Ab initio study of the mechanism for photoinduced Yl-oxygen exchange in uranyl(VI) in acidic aqueous solution.

    Science.gov (United States)

    Réal, Florent; Vallet, Valérie; Wahlgren, Ulf; Grenthe, Ingmar

    2008-09-03

    The mechanism for the photochemically induced isotope-exchange reaction U(17/18)O2(2+)(aq) + H2(16)O U(16)O2(2+)(aq) + H2(17/18)O has been studied using quantum-chemical methods. There is a dense manifold of states between 22,000 and 54,000 cm(-1) that results from excitations from the sigma(u) and pi(u) bonding orbitals in the (1)Sigma(g)(+) ground state to the nonbonding f(delta) and f(phi) orbitals localized on uranium. On the basis of investigations of the reaction profile in the (1)Sigma(g)(+) ground state and the excited states (3)Delta(g) (the lowest triplet state) and (3)Gamma(g) (one of the several higher triplet states), the latter two of which have the electron configurations sigma(u)f(delta) and pi(u)f(phi), respectively, we suggest that the isotope exchange takes place in one of the higher triplet states, of which the (3)Gamma(g) state was used as a representative. The geometries of the luminescent (3)Delta(g) state, the lowest in the sigma(u)f(delta,phi) manifold (the "sigma" states), and the (1)Sigma(g)(+) ground state are very similar, except that the bond distances are slightly longer in the former. This is presumably a result of transfer of a bonding electron to a nonbonding f orbital, which makes the excited state in some respects similar to uranyl(V). As is the case for all of the states of the pi(u)f(delta,phi) manifold (the "pi" states), the geometry of the (3)Gamma(g) state is very different from that of the (3)Delta(g) "sigma" state and has nonequivalent U-O(yl) distances of 1.982 and 1.763 A; in the (3)Gamma(g) state, the yl-exchange takes place by transfer of a proton or hydrogen from water to the more distant yl-oxygen. The activation barriers for proton/hydrogen transfer in the ground state and the (3)Delta(g) and (3)Gamma(g) states are 186, 219, and 84 kJ/mol, respectively. The relaxation energy for the (3)Gamma(g) state in the solvent after photoexcitation is -86 kJ/mol, indicating that the energy barrier can be overcome; the "pi

  4. Studies on foliicolous fungi VI

    NARCIS (Netherlands)

    Hosagoudar, V.B.

    2002-01-01

    An account is given of three foliicolous fungi from India. Two new species, viz. Clasterosporium cyperacearum and Questieriella grewiae are described. Dysrhynchis uncinata forms a new generic and specific record to India and is reported on an endemic host.

  5. CPE OF URANIUM (VI USING IONIC LIQUID

    Directory of Open Access Journals (Sweden)

    SANAA NAÏT-TAHAR

    2016-07-01

    Full Text Available Cloud point extraction (CPE was used to extract uranium (VI from an aqueous solution in acetate media. The methodology used is based on the formation of uranyl-ionic liquid (I complexes and uranyl-D2EHPA soluble in a micellar phase of non-ionic surfactant (Triton X-100. The uranium (VI complexes are then extracted into the surfactant-rich phase at ambient temperature. The ionic liquid (IL used as a chelating agent was synthesized and characterized in this study. It is composed of N-butyl N’-triethoxy methyl imidazolium cation and diethylhexylphosphate (D2EHPA-H as anion. The effect of the IL on the extraction efficiency was studied in presence and in absence of IL’s cation in acetate medium.

  6. Research Progress on the Study of Microorganisms in Treatment of Pollution by Cr(VI)%治理 Cr(VI)污染的微生物研究进展

    Institute of Scientific and Technical Information of China (English)

    胡玉婷

    2015-01-01

    综述了国内外治理Cr( VI)污染的微生物研究进展,介绍了已报道的部分对Cr( VI)有解毒作用的微生物,并重点综述了微生物耐受和去除Cr(VI)相关机理,包括微生物对Cr(VI)的吸附作用、直接还原作用、间接还原作用。此外,还对微生物去除Cr( VI)污染的研究发展趋势进行了展望。%The research progress on the study of microorganisms in treatment of pollution by Cr ( VI ) was summarized, which introduced the microorganisms reported in treating Cr ( VI ) pollution, especially the microbial tolerance as well as related mechanism, including adsorption, reduction directly and indirectly.In addition the trend of treating the pollution of Cr( VI) with microorganisms was prospected.

  7. BIOSORPTION OF CR (VI BY RESTING CELLS OF ASPERGILLUS SP.

    Directory of Open Access Journals (Sweden)

    M. Sen , M. Ghosh Dastidar

    2007-01-01

    Full Text Available Biosorption of Cr(VI from aqueous solution was studied in a batch bioreactor using the resting cells of filamentous fungal biomass (Aspergillus sp. isolated from industrial wastewaters. The specific Cr(VI removal (mg/g of dried biomass decreased with increase in pH and increased with increase in initial Cr(VI concentration, upto 500 mg/L. By increasing biomass concentration from 2.4 to 5.2 g/L, the specific metal removal remained almost constant. The studies carried out by using the resting cells from various stages of growth indicated maximum Cr(VI removal of 34.8 mg/g using the biomass from the beginning of the stationary phase. The adsorption equilibrium constants Qº (42.9 mg/g and b (0.0091/mg were obtained from the Langmuir adsorption isotherm model.

  8. ALTERATION OF U(VI)-PHASES UNDER OXIDIZING CONDITIONS

    Energy Technology Data Exchange (ETDEWEB)

    A.P. Deditius; S. Utsunomiya; R.C. Ewing

    2006-02-21

    Uranium-(VI) phases are the primary alteration products of the UO{sub 2} in spent nuclear fuel and the UO{sub 2+x}, in natural uranium deposits. The U(VI)-phases generally form sheet structures of edge-sharing UO{sub 2}{sup 2+} polyhedra. The complexity of these structures offers numerous possibilities for coupled-substitutions of trace metals and radionuclides. The incorporation of radionuclides into U(VI)-structures provides a potential barrier to their release and transport in a geologic repository that experiences oxidizing conditions. In this study, we have used natural samples of UO{sub 2+x}, to study the U(VI)-phases that form during alteration and to determine the fate of the associated trace elements.

  9. Vi-CRM 197 as a new conjugate vaccine against Salmonella Typhi.

    Science.gov (United States)

    Micoli, F; Rondini, S; Pisoni, I; Proietti, D; Berti, F; Costantino, P; Rappuoli, R; Szu, S; Saul, A; Martin, L B

    2011-01-17

    An efficacious, low cost vaccine against typhoid fever, especially for young children, would make a major impact on disease burden in developing countries. The virulence capsular polysaccharide of Salmonella Typhi (Vi) coupled to recombinant mutant Pseudomonas aeruginosa exoprotein A (Vi-rEPA) has been shown to be highly efficacious. We investigated the use of carrier proteins included in infant vaccines, standardized the conjugation process and developed key assays required for routine lot release at production scale. Vi from a BSL1 organism, Citrobacter freundii, strain WR7011, was used as an alternative to Vi from S. Typhi. We showed that Vi conjugated to CRM(197), a non-toxic mutant of diphtheria toxin, widely used in commercial vaccines, was produced at high yield. Vi-CRM(197) proved immunogenic in animal studies, even without adjuvant. Thus, Vi-CRM(197) appears to be a suitable candidate for the development of a commercially viable, effective typhoid vaccine for developing countries.

  10. [Multicenter study on the treatment and outcome of patients admitted to intensive care units in Italy. Presentation of the research project and the study protocol. GiViTI (Gruppo Italiano per la Valutazione degli interventi in Terapia Intensiva)].

    Science.gov (United States)

    Apolone, G; Brazzi, L; Pesce, C

    1992-12-01

    Although Intensive Care Units (ICU) are present in most of the Italian Hospitals for acute patients, the heterogeneity of the patients case-mix and the large variation in structural, organizational and staffing arrangements have limited the feasibility and precision of evaluation studies aimed at assessing the quality of health care delivered and its impact on patients outcomes. To our knowledge there has been no nationwide study aimed at assessing the quality and effectiveness of the delivered care in samples of ICUs and patients that are representative of the source populations. To study the effects of variations in health care practices on the outcome of the patients admitted in ICU, we designed a multicentric observational study involving 120 ICUs within the country. The present study is the first part of a project involving a network of Intensive Care Units gathered under the name of GiViTI-Italian Group for the Evaluation of the Interventions in Intensive Care-that is representative of the national Italian reality in the field. The idea of a large collaborative group acting in the field of Intensive Care stands in line with several quality, effectiveness and resource utilization studies that are ongoing in other European countries and is also the result of a series of smaller-scale experiences carried out by other Italian groups eventually emboied in the GiViTI project. In the framework of the ongoing long term, multisite, and multidisciplinary project, the present study calls for the recruitment of all consecutive patients seen at the participant centers during a two months period.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Sn(II) oxy-hydroxides as potential adsorbents for Cr(VI)-uptake from drinking water: An X-ray absorption study

    Energy Technology Data Exchange (ETDEWEB)

    Pinakidou, Fani; Kaprara, Efthimia [Aristotle University of Thessaloniki, School of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece); Katsikini, Maria; Paloura, Eleni C.; Simeonidis, Konstantinos [Aristotle University of Thessaloniki, School of Physics, Department of Solid State Physics, 54124 Thessaloniki (Greece); Mitrakas, Manassis, E-mail: manasis@eng.auth.gr [Aristotle University of Thessaloniki, School of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece)

    2016-05-01

    The feasibility of implementing a Sn(II) oxy-hydroxide (Sn{sub 6}O{sub 4}(OH){sub 4}) for the reduction and adsorption of Cr(VI) in drinking water treatment was investigated using XAFS spectroscopies at the Cr-K-edge. The analysis of the Cr-K-edge XANES and EXAFS spectra verified the effective use of Sn{sub 6}O{sub 4}(OH){sub 4} for successful Cr(VI) removal. Adsorption isotherms, as well as dynamic Rapid Small Scale Test (RSSCT) in NSF water matrix showed that Sn{sub 6}O{sub 4}(OH){sub 4} can decrease Cr(VI) concentration below the upcoming regulation limit of 10 μg/L for drinking water. Moreover, an uptake capacity of 7.2 μg/mg at breakthrough concentration of 10 μg/L was estimated from the RSSCT, while the residual Cr(VI) concentration ranged at sub-ppb level for a significant period of the experiment. Furthermore, no evidence for the formation of Cr(OH){sub 3} precipitates was found. On the contrary, Cr(III)-oxyanions were chemisorbed onto SnO{sub 2}, which was formed after Sn(II)-oxidation during Cr(VI)-reduction. Nevertheless, changes in the type of Cr(III)-inner sphere complexes were observed after increasing surface coverage: Cr(III)-oxyanions preferentially sorb in a geometry which combines both bidentate binuclear ({sup 2}C) and monodentate ({sup 1}V) geometries, at the expense of the present bidentate mononuclear ({sup 2}E) contributions. On the other hand, the pH during sorption does not affect the adsorption mechanism of Cr(III)-species. The implementation of Sn{sub 6}O{sub 4}(OH){sub 4} in water treatment technology combines the advantage of rapidly reducing a large amount of Cr(VI) due to donation of two electrons by Sn(II) and also the strong chemisorption of Cr(III) in a combination of the {sup 2}C and {sup 1}V configurations, which enhances the safe disposal of spent adsorbents. - Highlights: • Effective Cr(VI) removal from drinking water by Sn{sub 6}O{sub 4}(OH){sub 4} • Sn{sub 6}O{sub 4}(OH){sub 4} transformation to SnO{sub 2} after Cr(VI

  12. The involvement of ATP sulfurylase in Se(VI) and Cr(VI) reduction processes in the fission yeast Schizosaccharomyces pombe.

    Science.gov (United States)

    Raspor, P; Fujs, S; Banszky, L; Maraz, A; Batic, M

    2003-11-01

    The response of Schizosaccharomyces pombe towards the oxyanions selenate [Se(VI)] and dichromate [Cr(VI)] was investigated in order to establish the involvement of the yeast ATP sulfurylase in their reduction. An ATP sulfurylase-defective/selenate-resistant mutant of S. pombe (B-579 Se(R) -2) and an ATP sulfurylase-active/selenate-sensitive strain of S. pombe (B-579 Se(S)) were included in this study. The inhibitory effect of Se(VI) and Cr(VI) oxyanions on growth and bioaccumulation was measured. The sensitive strain showed natural sensitivity to selenate while the resistant mutant tolerated a 100-fold higher concentration of selenate. These results indicate that selenate toxicity to microorganisms is connected with the reduction of selenate to selenite. Both strains showed similar sensitivity to Cr(VI) and in this study there was no evidence that ATP sulfurylase participates in the reduction process of Cr(VI).

  13. Synthesis, characterization, and exciton dynamics of II-VI semiconducting nanomaterials and ab-initio studies for applications in explosives sensing

    OpenAIRE

    Cooper, Jason Kyle

    2013-01-01

    II-VI semiconducting nanostructures have been intensively researched as promising materials in applications including sensing, light emitting diodes (LEDs), lasers, photoelectrochemical (PEC) materials for water splitting and photo-catalysis, and dye or quantum dot sensitized solar cells. On the nanoscale, structural morphology plays a significant role in determining optical, electronic, and physical properties, and thus consequently affects the ultimate device properties. In zero-d...

  14. The capsular polysaccharide Vi from Salmonella typhi is a B1b antigen.

    Science.gov (United States)

    Marshall, Jennifer L; Flores-Langarica, Adriana; Kingsley, Robert A; Hitchcock, Jessica R; Ross, Ewan A; López-Macías, Constantino; Lakey, Jeremy; Martin, Laura B; Toellner, Kai-Michael; MacLennan, Calman A; MacLennan, Ian C; Henderson, Ian R; Dougan, Gordon; Cunningham, Adam F

    2012-12-15

    Vaccination with purified capsular polysaccharide Vi Ag from Salmonella typhi can protect against typhoid fever, although the mechanism for its efficacy is not clearly established. In this study, we have characterized the B cell response to this vaccine in wild-type and T cell-deficient mice. We show that immunization with typhoid Vi polysaccharide vaccine rapidly induces proliferation in B1b peritoneal cells, but not in B1a cells or marginal zone B cells. This induction of B1b proliferation is concomitant with the detection of splenic Vi-specific Ab-secreting cells and protective Ab in Rag1-deficient B1b cell chimeras generated by adoptive transfer-induced specific Ab after Vi immunization. Furthermore, Ab derived from peritoneal B cells is sufficient to confer protection against Salmonella that express Vi Ag. Expression of Vi by Salmonella during infection did not inhibit the development of early Ab responses to non-Vi Ags. Despite this, the protection conferred by immunization of mice with porin proteins from Salmonella, which induce Ab-mediated protection, was reduced postinfection with Vi-expressing Salmonella, although protection was not totally abrogated. This work therefore suggests that, in mice, B1b cells contribute to the protection induced by Vi Ag, and targeting non-Vi Ags as subunit vaccines may offer an attractive strategy to augment current Vi-based vaccine strategies.

  15. The distribution and kinematics of interstellar O VI in the Milky Way

    Science.gov (United States)

    Sarma, R.; Pathak, A.; Murthy, Jayant; Sarma, J. K.

    2017-02-01

    We present the results of a survey of interstellar O VI absorption in the Milky Way (MW) towards 69 stars in the Large Magellanic Cloud obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). The integrated MW O VI column densities log N(O VI) are in the range from 13.68 to 14.73 with a mean of 14.26_{-0.09}^{+0.07} atoms cm-2. The O VI exponential scale height is found to be 2.28 ± 1.06 kpc. The O VI column density correlates with the Doppler parameter b. The O VI velocity dispersion ranges from 14.0 to 91.6 with an average value of 62.7 km s-1. These high values of the velocity dispersion reveal the effect of turbulence, multiple velocity components and collision on broad O VI profiles. There is a significant variation of the O VI column density on all scales studied (0.0025°-6.35°). The smallest scale for which O VI column density variations has been found is Δθ ˜ 9 arcsec. A comparison of the O VI velocity profiles with Fe II indicates the presence of intermediate-velocity cloud and/or high-velocity cloud components in the O VI absorption.

  16. Voltammetric determination of Se(IV) and Se(VI) in saline samples-Studies with seawater, hydrothermal and hemodialysis fluids

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Paulo C. do, E-mail: npaulo@quimica.ufsm.br [Departamento de Quimica, Universidade Federal de Santa Maria, C.P. 5051, 97105-970 Santa Maria, RS (Brazil); Jost, Cristiane L.; Carvalho, Leandro M. de; Bohrer, Denise [Departamento de Quimica, Universidade Federal de Santa Maria, C.P. 5051, 97105-970 Santa Maria, RS (Brazil); Koschinsky, Andrea [School of Engineering and Science, Geosciences and Astrophysics, Jacobs University Bremen GmbH, P.O. Box 750561, D-28725 Bremen (Germany)

    2009-08-26

    Determination of Se(IV) and Se(VI) in high saline media was investigated by cathodic stripping voltammetry (CSV). The voltammetric method was applied to assay selenium in seawater, hydrothermal and hemodialysis fluids. The influence of ionic strength on selenium determination is discussed. The CSV method was based on the co-electrodeposition of Se(IV) with Cu(II) ions and Se(VI) determined by difference after sample UV-irradiation for photolytic selenium reduction. UV-irradiation was also used as sample pre-treatment for organic matter decomposition. Detection limit of 0.030 {mu}g L{sup -1} (240 s deposition time) and relative standard deviation (RSD) of 6.19% (n = 5) for 5.0 {mu}g L{sup -1} of Se(IV) were calculated. Linear calibration range for selenium was observed from 1.0 to 100.0 {mu}g L{sup -1}. Concerning the pre-treatment step, best results were obtained by using 60 min UV-irradiation interval in H{sub 2}O{sub 2}/HCl medium. Se(VI) was reduced to the Se(IV) electroactive species with recoveries between 91.7% and 112.9%. Interferents were also investigated.

  17. Efficacy and safety of vi-tetanus toxoid conjugated typhoid vaccine (PedaTyph™) in Indian children: School based cluster randomized study.

    Science.gov (United States)

    Mitra, Monjori; Shah, Nitin; Ghosh, Apurba; Chatterjee, Suparna; Kaur, Iqbal; Bhattacharya, Nisha; Basu, Suparna

    2016-04-01

    Vi polysaccharide typhoid vaccines cannot be used in children vaccine prepared by binding Vi to tetanus toxoids (Vi-TT) induces protective levels even in children vaccination with a Vi-TT vaccine in children 6 months to 12 years of age. Overall, 1765 subjects were recruited from two registered municipal urban slums of southern Kolkata. Most of the children of the slum dwellers attended the schools in the locality which was selected with permission from the school authority. Schools were randomly divided into vaccinated (Test group) and unvaccinated group (Control group). Children and their siblings of test group received 2-doses of PedaTyph™ vaccine at 6 weeks interval. Control group received vaccines as per national guidelines. Adverse events (AEs) were examined after 30 minutes, 1 month and clinical events were observed till 12 months post-vaccination. Incidence of culture positive typhoid fever in the control group was 1.27% vis-a-vis none in vaccine group during 12 months. In subgroup evaluated for immunogenicity, an antibody titer value of 1.8 EU/ml (95% CI: 1.5 EU/ml, 2.2 EU/ml), 32 EU/ml (95% CI: 27.0 EU/ml, 39.0 EU/ml) and 14 EU/ml (95% CI: 12.0 EU/ml, 17.0 EU/ml) at baseline, 6 weeks and 12 months, respectively was observed. Sero-conversion among the sub-group was 100% after 6 weeks of post-vaccination and 83% after 12 months considering 4-fold rise from baseline. The efficacy of vaccine was 100 % (95% CI: 97.6%, 100%) in the first year of follow-up with minimal AEs post vaccination. Vi conjugate typhoid vaccine conferred 100% protection against typhoid fever in 1765 children 6 months to 12 years of age with high immunogenicity in a subgroup from the vaccine arm.

  18. VI-14, a novel flavonoid derivative, inhibits migration and invasion of human breast cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Fanni; Li, Chenglin; Zhang, Haiwei; Lu, Zhijian [State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Carcinogenesis and Intervention, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009 (China); Li, Zhiyu; You, Qidong [Department of Medicinal Chemistry, China Pharmaceutical University, Nanjing 210009 (China); Lu, Na [State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Carcinogenesis and Intervention, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009 (China); Guo, Qinglong, E-mail: anticancer_drug@yahoo.com.cn [State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Carcinogenesis and Intervention, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009 (China)

    2012-06-01

    It has been well characterized that flavonoids possess pronounced anticancer potentials including anti-angiogenesis, anti-metastasis, and pro-apoptosis. Herein, we report, for the first time, that VI-14, a novel flavonoid derivative, possesses anti-cancer properties. The purpose of this study is to investigate the anti-migration and anti-invasion activities of VI-14 in breast cancer cells. Our data indicate that VI-14 inhibits adhesion, migration and invasion of MDA-MB-231 and MDA-MB-435 human breast cancer cells. MDA-MB-231 cells treated with VI-14 display reduced activities and expressions of ECM degradation-associated proteins including matrix metalloproteinase 2 (MMP-2) and 9 (MMP-9) at both the protein and mRNA levels. Meanwhile, VI-14 treatment induces an up-regulated expression of tissue inhibitor of metalloproteinase 1 (TIMP-1) and 2 (TIMP-2) in MDA-MB-231 cells. Western blotting results show that phosphorylation levels of critical components of the MAPK signaling pathway, including ERK, JNK and P38, are dramatically decreased in VI-14-treated MDA-MB-231 cells. Furthermore, treatment of VI-14 significantly decreases the nuclear levels and the binding ability of nuclear factor-kappa B (NF-κB) and activator protein-1 (AP-1). Taken together, our data suggest that VI-14 treatment suppresses migration and motility of breast cancer cells, and VI-14 may be a potential compound for cancer therapy. Highlights: ► We report for the first time that VI-14 possesses anti-cancer properties. ► VI-14 weakens the adhesion, migration and invasion of human breast cancer cells. ► VI-14 decreases the activities and expressions of MMP-2/9. ► VI-14 suppresses the phosphorylation levels of the MAPK signaling pathway. ► VI-14 decreases the nuclear levels and the binding ability of NF-κB and AP-1.

  19. New approach in modeling Cr(VI) sorption onto biomass from metal binary mixtures solutions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chang [College of Environmental Science and Engineering, Anhui Normal University, South Jiuhua Road, 189, 241002 Wuhu (China); Chemical Engineering Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain); Fiol, Núria [Chemical Engineering Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain); Villaescusa, Isabel, E-mail: Isabel.Villaescusa@udg.edu [Chemical Engineering Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain); Poch, Jordi [Applied Mathematics Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain)

    2016-01-15

    In the last decades Cr(VI) sorption equilibrium and kinetic studies have been carried out using several types of biomasses. However there are few researchers that consider all the simultaneous processes that take place during Cr(VI) sorption (i.e., sorption/reduction of Cr(VI) and simultaneous formation and binding of reduced Cr(III)) when formulating a model that describes the overall sorption process. On the other hand Cr(VI) scarcely exists alone in wastewaters, it is usually found in mixtures with divalent metals. Therefore, the simultaneous removal of Cr(VI) and divalent metals in binary mixtures and the interactive mechanism governing Cr(VI) elimination have gained more and more attention. In the present work, kinetics of Cr(VI) sorption onto exhausted coffee from Cr(VI)–Cu(II) binary mixtures has been studied in a stirred batch reactor. A model including Cr(VI) sorption and reduction, Cr(III) sorption and the effect of the presence of Cu(II) in these processes has been developed and validated. This study constitutes an important advance in modeling Cr(VI) sorption kinetics especially when chromium sorption is in part based on the sorbent capacity of reducing hexavalent chromium and a metal cation is present in the binary mixture. - Highlights: • A kinetic model including Cr(VI) reduction, Cr(VI) and Cr(III) sorption/desorption • Synergistic effect of Cu(II) on Cr(VI) elimination included in the model • Model validation by checking it against independent sets of data.

  20. Silicon nanoparticles (SiNp) alleviate chromium (VI) phytotoxicity in Pisum sativum (L.) seedlings.

    Science.gov (United States)

    Tripathi, Durgesh Kumar; Singh, Vijay Pratap; Prasad, Sheo Mohan; Chauhan, Devendra Kumar; Dubey, Nawal Kishore

    2015-11-01

    The present study was aimed to investigate the effect of silicon nanoparticles (SiNp) against Cr (VI) phytotoxicity in pea seedlings. Results show that Cr(VI, 100 μM) significantly (P < 0.05) declined growth of pea which was accompanied by the enhanced level of Cr. Additionally, photosynthetic pigments and chlorophyll fluorescence parameters like F(v)/F(m), F(v)/F0 and qP were decreased while NPQ significantly (P < 0.05) increased under Cr(VI) treatment. Superoxide radical, hydrogen peroxide and malondialdehyde (MDA-lipid peroxidation) contents were enhanced by Cr(VI). Activities of antioxidant enzymes like superoxide dismutase and ascorbate peroxidase were increased by Cr (VI) while activities of catalase, glutathione reductase and dehydroascorbate reductase were inhibited significantly (P < 0.05). Micro and macronutrients also show decreasing trends (except S) under Cr(VI) treatment. However, addition of SiNp together with Cr(VI) protects pea seedlings against Cr(VI) phytotoxicity hence improved growth was noticed. In conclusion, the results of this study show that Cr(VI) causes negative impact on pea seedlings, however; SiNp protects pea seedlings against Cr(VI) phytotoxicity by reducing Cr accumulation and oxidative stress, and up-regulating antioxidant defense system and nutrient elements.

  1. Dynamics of microbial community during bioremediation of phenanthrene and chromium(VI)-contaminated soil microcosms.

    Science.gov (United States)

    Ibarrolaza, Agustín; Coppotelli, Bibiana M; Del Panno, María T; Donati, Edgardo R; Morelli, Irma S

    2009-02-01

    The combined effect of phenanthrene and Cr(VI) on soil microbial activity, community composition and on the efficiency of bioremediation processes has been studied. Biometer flask systems and soil microcosm systems contaminated with 2,000 mg of phenanthrene per kg of dry soil and different Cr(VI) concentrations were investigated. Temperature, soil moisture and oxygen availability were controlled to support bioremediation. Cr(VI) inhibited the phenanthrene mineralization (CO(2) production) and cultivable PAH degrading bacteria at levels of 500-2,600 mg kg(-1). In the bioremediation experiments in soil microcosms the degradation of phenanthrene, the dehydrogenase activity and the increase in PAH degrading bacteria counts were retarded by the presence of Cr(VI) at all studied concentrations (25, 50 and 100 mg kg(-1)). These negative effects did not show a correlation with Cr(VI) concentration. Whereas the presence of Cr(VI) had a negative effect on the phenanthrene elimination rate, co-contamination with phenanthrene reduced the residual Cr(VI) concentration in the water exchangeable Cr(VI) fraction (WEF) in comparison with the soil microcosm contaminated only with Cr(VI). Clear differences were found between the denaturing gradient gel electrophoresis (DGGE) patterns of each soil microcosm, showing that the presence of different Cr(VI) concentrations did modulate the community response to phenanthrene and caused perdurable changes in the structure of the microbial soil community.

  2. Doping anatase TIO_{2} with group V-b and VI-b transition metal atoms : a hybrid functional first-principles study

    OpenAIRE

    Matsubara, Masahiko; Saniz, Rolando; Partoens, Bart; Lamoen, Dirk

    2017-01-01

    Abstract: We investigate the role of transition metal atoms of group V-b (V, Nb, and Ta) and VI-b (Cr, Mo, and W) as n- or p-type dopants in anatase TiO2 using thermodynamic principles and density functional theory with the HeydScuseriaErnzerhof HSE06 hybrid functional. The HSE06 functional provides a realistic value for the band gap, which ensures a correct classification of dopants as shallow or deep donors or acceptors. Defect formation energies and thermodynamic transition levels are calc...

  3. Vi har brug for skammere

    DEFF Research Database (Denmark)

    Holm, Claus

    2007-01-01

    Skammen er en væsentlig ingrediens i opdragelsen af børn, men det overser vi, for skam er et fyord i den pædagogiske verden. Interview med børnebogsforfatteren Lene Kaaberbøl om, hvorfor skam gør os menneskelige....

  4. VI Tallinna arhitektuuritriennaal / Leonhard Lapin

    Index Scriptorium Estoniae

    Lapin, Leonhard, 1947-

    2005-01-01

    15.-17. IX Tallinnas Niguliste kirikus toimuval VI Tallinna arhitektuuritriennaalil esinevad inglise arhitektuurikriitik Peter Davey, šveitsi arhitekt Peter Zumthor, soome arhitekt Juha Leviskä, eesti arhitekt Vilen Künnapu, eesti kunstiajaloolane Juhan Maiste jt. Külastatakse KUMU, tutvutab autor Pekka Vapaavuori

  5. Hvad skal vi med et naturhistorisk museum?

    DEFF Research Database (Denmark)

    Kjærgaard, Peter C.

    2016-01-01

    I Danmark har vi nationale museer for kunsten, kulturen og naturen. Vi er i fuld gang med at lave et nyt, stort supermuseum for naturhistorien. Hvad skal vi egentlig med det? Efter et år på posten som direktør for Statens Naturhistoriske Museum gør Peter C. Kjærgaard status med en personlig...

  6. The Vi conjugate typhoid vaccine is safe, elicits protective levels of IgG anti-Vi, and is compatible with routine infant vaccines.

    Science.gov (United States)

    Thiem, Vu Dinh; Lin, Feng-Ying C; Canh, Do Gia; Son, Nguyen Hong; Anh, Dang Duc; Mao, Nguyen Duc; Chu, Chiayung; Hunt, Steven W; Robbins, John B; Schneerson, Rachel; Szu, Shousun C

    2011-05-01

    Typhoid fever remains a serious problem in developing countries. Current vaccines are licensed for individuals who are 5 years old or older. A conjugate of the capsular polysaccharide (CP) of Salmonella enterica serovar Typhi (Vi) bound to recombinant exoprotein A of Pseudomonas aeruginosa (Vi-rEPA) enhanced Vi immunogenicity and protected 2- to 5-year-olds in Vietnam. In this study, Vi-rEPA was evaluated for use in infants. A total of 301 full-term Vietnamese infants received Expanded Program on Immunization (EPI) vaccines alone or with Vi-rEPA or Haemophilus influenzae type b-tetanus toxoid conjugate (Hib-TT) at 2, 4, and 6 months and Vi-rEPA or Hib-TT alone at 12 months. Infants were visited 6, 24, and 48 h after each injection to monitor adverse reactions. Maternal, cord, and infant sera were assayed for IgG anti-Vi and for IgG antibodies to Hib CP and the diphtheria, tetanus, and pertussis toxins at 7, 12, and 13 months. No vaccine-related serious adverse reactions occurred. In the Vi-rEPA group, the IgG anti-Vi geometric mean (GM) increased from the cord level of 0.66 to 17.4 enzyme-linked immunosorbent assay units (EU) at 7 months, declined to 4.76 EU at 12 months, and increased to 50.1 EU 1 month after the 4th dose (95% of infants had levels of ≥ 3.5 EU, the estimated protective level). Controls had no increase of the IgG anti-Vi GM. Infants with cord anti-Vi levels of <3.5 EU responded with significantly higher IgG anti-Vi levels than those with levels of ≥ 3.5 EU. Anti-diphtheria, -tetanus, and -pertussis toxin levels were similar in all groups. Vi-rEPA was safe, induced protective anti-Vi levels, and was compatible with EPI vaccines, and it can be used in infants. High cord IgG anti-Vi levels partially suppressed infant responses to Vi-rEPA.

  7. Recent Developments of Ferrate (VI) Salts as Cathode Meterial in High Capacity Batteries%铁(VI)酸盐正极材料的研究进展

    Institute of Scientific and Technical Information of China (English)

    袁中直; 周震涛; 李伟善

    2002-01-01

      The ferrate (VI) salts that have Fe element in an unusual VI valence state may be one of the best choices of high-energy batteries' cathode material, because ferrates (VI) are capable of the three-electron reduction, their reduction and decomposition products are nontoxic and environment-benign. One and a half century after the K2FeO4 synthesis, the chemistry and electrochemistry remains relatively unknown because of the incorrect knowledge of ferrates (VI) instability. The studies of ferrates (VI) used as cathode have been renewed recently. Many achievements have been made after the Israeli scientist Dr. Stuart Licht published their results on Science magazine that the alkaline ferrate (VI)/Zn batteries can provide 50% higher capacity than conventional alkaline batteries. In this article, the reasons of ferrate (VI) salts’ instability, methods of avoiding ferrate (VI) salts' decomposition and influences of some modifiers such as SrTiO3, Co2O3,MnO2,In2O3,KMnO4, (CFx)n on electrochemical characteristics of ferrate (VI) cathode are reviewed.%  铁(VI)酸盐中的Fe具有不寻常的高价态+6价,可以进行3电子还原放电反应,其还原产物及分解产物无毒无害,具有新一代“绿色电池”的重要特征。铁(VI)酸盐合成一个半世纪以来,由于认为它不稳定至今其化学和电化学性质并不很清楚。直到1999年以色列科学家Licht博士在Science上发表研究结果表明铁(VI)酸盐/Zn电池可以获得比常规碱性电池多50%的容量,铁(VI)酸盐高能电池才又引起深入的研究。本文综述了近年来铁(VI)酸盐作为高能电池正极活性物质的研究进展,包括改善铁(VI)酸盐稳定性的方法、掺杂修饰(如SrTiO3, Co2O3,MnO2,In2O3,KMnO4,(CFx)n等)等改善铁(VI)酸盐正极电化学性能的技术等。

  8. The use of endomarketing in credit unions: a case study of the UFVCredi and the Unicred-Viçosa O emprego do endomarketing em cooperativas de crédito: estudo de caso da UFV-Credi e da Unicred-Viçosa

    Directory of Open Access Journals (Sweden)

    Henrique Lopes Dornelas

    2002-11-01

    Full Text Available Endomarketing can be considered as a group of activities concerned with the internal aspects of the organization, whose purpose is to value the human being. In order to become competitive, the Credit Unions should adopt Endomarketing strategies that combine motivation, training and communication elements. The purpose of the present work was to verify how the Credit Union of the Workers of the Federal University of Viçosa Ltd. / UFV-CREDI and the Credit Union of the Doctors and Health-related Professionals of Viçosa Ltd. – UNICRED/VIÇOSA – MG are using the tools offered by Endomarketing. In the methodology, a study concerning the Endomarketing and the Credit Unions war carried out. After that, the employees and the members of the Credit Unions were asked to answer a questionnaire. After the analysis of the obtained data, it was concluded that UFV-CREDI and UNICRED/VIÇOSA-MG have effectively reached their objectives because their Endomarketing strategies have presented positive results, making it possible for them to get new members as well as to keep their members and employees motivated and satisfied with the products and services offered by the Credit Unions.O Endomarketing pode ser conceituado como um conjunto de atividades voltadas para o interior da organização, cuja finalidade é valorizar o ser humano. Para que as cooperativas de crédito sejam competitivas, elas devem adotar estratégias de Endomarketing, que combinem elementos de motivação, treinamento e comunicação. Procurou-se com o presente estudo, verificar como a Cooperativa de Economia e Crédito Mútuo dos Servidores da Universidade Federal de Viçosa – LTDA / UFV-CREDI e a Cooperativa de Economia e Crédito Mútuo dos Médicos e demais Profissionais da Saúde de Viçosa Ltda – UNICRED/VIÇOSA-MG estão utilizando as ferramentas oferecidas pelo Endomarketing. Na metodologia foi realizado um estudo acerca do Endomarketing e das cooperativas de crédito, para

  9. Uranium(VI) reduction by iron(II) monosulfide mackinawite.

    Science.gov (United States)

    Hyun, Sung Pil; Davis, James A; Sun, Kai; Hayes, Kim F

    2012-03-20

    Reaction of aqueous uranium(VI) with iron(II) monosulfide mackinawite in an O(2) and CO(2) free model system was studied by batch uptake measurements, equilibrium modeling, and L(III) edge U X-ray absorption spectroscopy (XAS). Batch uptake measurements showed that U(VI) removal was almost complete over the wide pH range between 5 and 11 at the initial U(VI) concentration of 5 × 10(-5) M. Extraction by a carbonate/bicarbonate solution indicated that most of the U(VI) removed from solution was reduced to nonextractable U(IV). Equilibrium modeling using Visual MINTEQ suggested that U was in equilibrium with uraninite under the experimental conditions. X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy showed that the U(IV) phase associated with mackinawite was uraninite. Oxidation experiments with dissolved O(2) were performed by injecting air into the sealed reaction bottles containing mackinawite samples reacted with U(VI). Dissolved U measurement and XAS confirmed that the uraninite formed from the U(VI) reduction by mackinawite did not oxidize or dissolve under the experimental conditions. This study shows that redox reactions between U(VI) and mackinawite may occur to a significant extent, implying an important role of the ferrous sulfide mineral in the redox cycling of U under sulfate reducing conditions. This study also shows that the presence of mackinawite protects uraninite from oxidation by dissolved O(2). The findings of this study suggest that uraninite formation by abiotic reduction by the iron sulfide mineral under low temperature conditions is an important process in the redistribution and sequestration of U in the subsurface environments at U contaminated sites.

  10. The scatter about the "Universal" dwarf spheroidal mass profile: A kinematic study of the M31 satellites, And V and And VI

    CERN Document Server

    Collins, M L M; Rich, R M; Ibata, R A; Irwin, M J; Peñarrubia, J; Arimoto, N; Brooks, A M; Lewis, G F; McConnachie, A W; Venn, K

    2011-01-01

    While the satellites of the Milky Way (MW) have been shown to be largely consistent in terms of their mass contained within one half--light radius (M_{half}) with a "Universal" mass profile, a number of M31 satellites are found to be inconsistent with such relations, and seem kinematically colder in their central regions than their MW cousins. In this work, we present new kinematic and updated structural properties for two M31 dSphs, And V and And VI using data from the Keck Low Resolution Imaging Spectrograph (LRIS) and the DEep Imaging Multi-Object Spectrograph (DEIMOS) instruments and the Subaru Suprime-Cam imager. We measure systemic velocities of v_r=-393.1+/-4.2km/s and -344.8+/-2.5km/s, and dispersions of sigma_v=11.5{+5.3}{-4.4}km/s and sigma_v=9.4{+3.2}{-2.4}km/s for And V and And VI respectively, meaning these two objects are consistent with the trends in sigma_v and r_{half} set by their MW counterparts. We also investigate the nature of this scatter about the MW dSph mass profiles for the "Classic...

  11. Semiconductors A(III)B(VI): Translation

    Science.gov (United States)

    Akhundov, G. A.; Abdullaev, G. B.; Guseynov, G. D.; Mekhtiyev, R. F.; Aliyeva, M. Kh.

    1993-11-01

    Semiconductors A(III) B(VI) crystallize in laminated or chain structures and contain nine valence electrons in each molecule. Connection in the layers and the chains is predominantly covalent, and Van der Waal between the layers and the chains. Calculated data of the energy spectrum of these compounds are absent, and the available experimental studies are insufficient for understanding of the zone structures. We have obtained and studied single crystals of GaS, GaSe, GaTe, InSe, and TiSe.

  12. Molecular evolution of type VI intermediate filament proteins

    Directory of Open Access Journals (Sweden)

    Vincent Michel

    2007-09-01

    Full Text Available Abstract Background Tanabin, transitin and nestin are type VI intermediate filament (IF proteins that are developmentally regulated in frogs, birds and mammals, respectively. Tanabin is expressed in the growth cones of embryonic vertebrate neurons, whereas transitin and nestin are found in myogenic and neurogenic cells. Another type VI IF protein, synemin, is expressed in undifferentiated and mature muscle cells of birds and mammals. In addition to an IF-typical α-helical core domain, type VI IF proteins are characterized by a long C-terminal tail often containing distinct repeated motifs. The molecular evolution of type VI IF proteins remains poorly studied. Results To examine the evolutionary history of type VI IF proteins, sequence comparisons, BLAST searches, synteny studies and phylogenic analyses were performed. This study provides new evidence that tanabin, transitin and nestin are indeed orthologous type VI IF proteins. It demonstrates that tanabin, transitin and nestin genes share intron positions and sequence identities, have a similar chromosomal context and display closely related positions in phylogenic analyses. Despite this homology, fast evolution rates of their C-terminal extremity have caused the appearance of repeated motifs with distinct biological activities. In particular, our in silico and in vitro analyses of their tail domain have shown that (avian transitin, but not (mammalian nestin, contains a repeat domain displaying nucleotide hydrolysis activity. Conclusion These analyses of the evolutionary history of the IF proteins fit with a model in which type VI IFs form a branch distinct from NF proteins and are composed of two major proteins: synemin and nestin orthologs. Rapid evolution of the C-terminal extremity of nestin orthologs could be responsible for their divergent functions.

  13. Importance of c-Type cytochromes for U(VI reduction by Geobacter sulfurreducens

    Directory of Open Access Journals (Sweden)

    Leang Ching

    2007-03-01

    Full Text Available Abstract Background In order to study the mechanism of U(VI reduction, the effect of deleting c-type cytochrome genes on the capacity of Geobacter sulfurreducens to reduce U(VI with acetate serving as the electron donor was investigated. Results The ability of several c-type cytochrome deficient mutants to reduce U(VI was lower than that of the wild type strain. Elimination of two confirmed outer membrane cytochromes and two putative outer membrane cytochromes significantly decreased (ca. 50–60% the ability of G. sulfurreducens to reduce U(VI. Involvement in U(VI reduction did not appear to be a general property of outer membrane cytochromes, as elimination of two other confirmed outer membrane cytochromes, OmcB and OmcC, had very little impact on U(VI reduction. Among the periplasmic cytochromes, only MacA, proposed to transfer electrons from the inner membrane to the periplasm, appeared to play a significant role in U(VI reduction. A subpopulation of both wild type and U(VI reduction-impaired cells, 24–30%, accumulated amorphous uranium in the periplasm. Comparison of uranium-accumulating cells demonstrated a similar amount of periplasmic uranium accumulation in U(VI reduction-impaired and wild type G. sulfurreducens. Assessment of the ability of the various suspensions to reduce Fe(III revealed no correlation between the impact of cytochrome deletion on U(VI reduction and reduction of Fe(III hydroxide and chelated Fe(III. Conclusion This study indicates that c-type cytochromes are involved in U(VI reduction by Geobacter sulfurreducens. The data provide new evidence for extracellular uranium reduction by G. sulfurreducens but do not rule out the possibility of periplasmic uranium reduction. Occurrence of U(VI reduction at the cell surface is supported by the significant impact of elimination of outer membrane cytochromes on U(VI reduction and the lack of correlation between periplasmic uranium accumulation and the capacity for uranium

  14. Removal of Cr(VI) by zero-valent, iron-encapsulated alginate beads

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xue Song; Tang, Yu Jun; Chen, Li Fang; Li, Fei Yan; Wan, Wen Ya; Tan, Ye Bin [Department of Chemical Engineering, Huaihai Institute of Technology, Jiangsu (China)

    2010-03-15

    Zero-valent, iron-encapsulated alginate beads were synthesized and were applied for the removal of Cr(VI) from aqueous solutions. The effects of several important parameters including solution pH, contact time, initial concentration and reaction temperature on Cr(VI) removal levels were investigated in batch studies. An initial solution pH of 1.0 was seen to be most favorable for Cr(VI) removal. The removal process was quick and almost 80% of the removal was attained within 60 min. The kinetic data followed the second-order equation well. The Cr(VI) removal was almost reaction temperature-independent and decreased with an increase in Cr(VI) initial concentration. The removal of Cr(VI) by iron-encapsulated alginate beads was found to be significantly higher than that of non-encapsulated alginate beads. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  15. Immunohistochemical expression of type VI collagen in superficial fibromatoses.

    Science.gov (United States)

    Magro, G; Colombatti, A; Lanzafame, S

    1995-10-01

    The expression of type VI collagen was studied immunohistochemically in 26 cases of superficial fibromatoses (palmar, plantar and penile) using an immunoperoxidase method for light microscopic visualization. The polyclonal antibody against type VI collagen used in this study was isolated from human placenta and its specifity was tested by immunoblotting assay. All cases consisted of multiple nodules showing a variable degree of cellularity and fibrosis. Depending on the predominant histological appearance of these nodules, each case was assigned to the three following phases: proliferative, involutional and residual. Morphologically normal palmar and plantar aponeuroses were included as controls. Immunohistochemical findings showed that type VI collagen was present as longitudinal thin fibers in normal palmar and plantar aponeuroses. A differential expression of this collagen was found in the different stages of superficial fibromatoses. Type VI collagen was markedly expressed as a distinct fibrillar network in the extracellular matrix (ECM) surrounding proliferating stromal cells in proliferative and involutional phases. Its expression completely disappeared from the connective tissue undergoing fibrotic transformation during involutional and residual phases. The results of the present study suggest that type VI collagen is an extracellular marker of stromal tissue proliferation and is involved in the early phases of tissue remodelling occurring in the superficial fibromatoses.

  16. Treatment of combined sewer overflows using ferrate (VI).

    Science.gov (United States)

    Gandhi, Rohan; Ray, Ajay K; Sharma, Virender K; Nakhla, George

    2014-11-01

    This paper presents the results of a study conducted on the treatment of combined sewer overflows using ferrate (VI) [Fe (VI)]. At a Fe (VI) dose of 0.24 mg/L, total chemical oxygen demand (TCOD), soluble chemical oxygen demand (SCOD), total biochemical oxygen demand (TBOD5), soluble biochemical oxygen demand (SBOD5), total suspended solids (TSS), volatile suspended solids (VSS), total phosphorus (TP), total nitrogen (TN), and soluble TN removal efficiencies of 71, 75, 69, 68, 72, 83, 64, 38, and 36%, respectively, were achieved. Kinetic studies revealed that a contact time of only 15 minutes is sufficient to achieve secondary effluent criteria. An innovative technique of using primary sludge (PS) and thickened waste activated sludge as a source for the in situ synthesis of ferrate was developed. A comparative study of treatment efficiencies achieved by Fe (VI) generated from different sources was done. At 0.1 mg/L dose of Fe (VI) synthesized from PS, TCOD, SCOD, TSS, VSS, TP, and TN removal efficiencies of 60, 62, 63, 67, 30, and 25%, respectively, were achieved.

  17. Cr(VI) Adsorption on Red Mud Modified by Lanthanum: Performance, Kinetics and Mechanisms

    Science.gov (United States)

    Cui, You-Wei; Li, Jie; Du, Zhao-Fu; Peng, Yong-Zhen

    2016-01-01

    Water pollution caused by the highly toxic metal hexavalent chromium (Cr(VI)) creates significant human health and ecological risks. In this study, a novel adsorbent was used to treat Cr(VI)-containing wastewater; the adsorbent was prepared using red mud (RM) generated from the alumina production industry and the rare earth element lanthanum. This study explored adsorption performance, kinetics, and mechanisms. Results showed that the adsorption kinetics of the RM modified by lanthanum (La-RM), followed the pseudo-second-order model, with a rapid adsorption rate. Cr(VI) adsorption was positively associated with the absorbent dose, pH, temperature, and initial Cr(VI) concentration; coexisting anions had little impact. The maximum Cr(VI) adsorption capacity was 17.35 mg/g. Cr(VI) adsorption on La-RM was a mono-layer adsorption pattern, following the Langmuir isotherm model. Thermodynamic parameters showed the adsorption was spontaneous and endothermic. The adsorption of Cr(VI) on La-RM occurred as a result of LaOCl formation on the RM surface, which in turn further reacted with Cr(VI) in the wastewater. This study highlighted a method for converting industrial waste into a valuable material for wastewater treatment. The novel absorbent could be used as a potential adsorbent for treating Cr(VI)-contaminating wastewater, due to its cost-effectiveness and high adsorption capability. PMID:27658113

  18. Cr(VI) Adsorption on Red Mud Modified by Lanthanum: Performance, Kinetics and Mechanisms.

    Science.gov (United States)

    Cui, You-Wei; Li, Jie; Du, Zhao-Fu; Peng, Yong-Zhen

    Water pollution caused by the highly toxic metal hexavalent chromium (Cr(VI)) creates significant human health and ecological risks. In this study, a novel adsorbent was used to treat Cr(VI)-containing wastewater; the adsorbent was prepared using red mud (RM) generated from the alumina production industry and the rare earth element lanthanum. This study explored adsorption performance, kinetics, and mechanisms. Results showed that the adsorption kinetics of the RM modified by lanthanum (La-RM), followed the pseudo-second-order model, with a rapid adsorption rate. Cr(VI) adsorption was positively associated with the absorbent dose, pH, temperature, and initial Cr(VI) concentration; coexisting anions had little impact. The maximum Cr(VI) adsorption capacity was 17.35 mg/g. Cr(VI) adsorption on La-RM was a mono-layer adsorption pattern, following the Langmuir isotherm model. Thermodynamic parameters showed the adsorption was spontaneous and endothermic. The adsorption of Cr(VI) on La-RM occurred as a result of LaOCl formation on the RM surface, which in turn further reacted with Cr(VI) in the wastewater. This study highlighted a method for converting industrial waste into a valuable material for wastewater treatment. The novel absorbent could be used as a potential adsorbent for treating Cr(VI)-contaminating wastewater, due to its cost-effectiveness and high adsorption capability.

  19. Vi mangler endnu et panel

    DEFF Research Database (Denmark)

    Ritter, Thomas

    2016-01-01

    Vi mangler højtuddannede værdiskabere, som transformerer gode idéer og teknologier til indtjening og velstand. Først i mødet med markedet afgøres fremtiden. Troels Lund Poulsen bør nedsætte et kommercialiseringspanel, der byder ind med løsninger, hvordan Danmark bliver et land ikke kun med gode i...

  20. U(VI) and Eu(III) ion sorption in the interface solution-phosphate solids: Structural study and mechanisms; Sorption des ions U(VI) et Eu(III) a l`interface solution - solides phosphates: Etude structurale et mechanismes

    Energy Technology Data Exchange (ETDEWEB)

    Drot, Romuald [Inst. de Physique Nucleaire, Paris-11 Univ., 91 - Orsay (France)

    1998-09-18

    As part of the storage of nuclear wastes in a deep underground disposal, radionuclides sorption on geological or engineered barriers is one of the most important factor which could enhance retardation. Thus, the knowledge of such mechanisms is needed. For this purpose, we chose to experimentally define sorption equilibria before performing simulation of retention data. Several phosphate compounds are potential candidates as engineered barrier additives. We considered Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}, Zr{sub 2}O(PO{sub 4}){sub 2} which allow to study the effect of PO{sub 4} and P{sub 2}O{sub 7} groups separately. Eu(III) and U(IV) ions were used as structural probes in order to simulate actinides (III) and (VI) behavior. X-ray powder diffraction, IR spectroscopy and electron probe microanalysis were used to characterized the synthesized solids. Electrophoretic measurements showed an amphoteric behavior of surface sites. Moreover, laser spectro-fluorimetry experiments indicated that no diffusion phenomena of the sorbed ion inside the solid occurs. Thus, we considered that a surface complexation model should be applied. Laser spectro-fluorimetry and XPS allowed to determine the nature of surface sites. ZrP{sub 2}O{sub 7} presents only one single site (P{sub 2}O{sub 7} groups) whereas Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7} and Zr{sub 2}O(PO{sub 4}){sub 2} admit two types of sites (PO{sub 4}/P{sub 2}O{sub 7} and PO{sub 4}/oxo groups, respectively). Sorbed species were identified using laser spectro-fluorimetry which indicate that, in KNO{sub 3} 0.5 M medium and for a known surface site, there are two surface complexes for U(VI) (sorption of UO{sup 2+}{sub 2} et de UO{sub 2}NO{sup +}{sub 3} species) and only one for Eu(III) (sorption of EuNO{sup 2+}{sub 3}). They are linked to the substrate as bidentate inner sphere complexes (EXAFS study). Surface acidity constants were determined by simulation of potentiometric titration curves obtained for each solid

  1. Biosorption of aqueous chromium(VI) by Tamarindus indica seeds.

    Science.gov (United States)

    Agarwal, G S; Bhuptawat, Hitendra Kumar; Chaudhari, Sanjeev

    2006-05-01

    The effectiveness of low cost agro-based materials namely, Tamarindus indica seed (TS), crushed coconut shell (CS), almond shell (AS), ground nut shell (GS) and walnut shell (WS) were evaluated for Cr(VI) removal. Batch test indicated that hexavalent chromium sorption capacity (q(e)) followed the sequence q(e)(TS) > q(e)(WS) > q(e)(AS) > q(e)(GS) > q(e)(CS). Due to high sorptive capacity, tamarind seed was selected for detailed sorption studies. Sorption kinetic data followed first order reversible kinetic fit model for all the sorbents. The equilibrium conditions were achieved within 150 min under the mixing conditions employed. Sorption equilibria exhibited better fit to Freundlich isotherms (R>0.92) than Langmuir isotherm (R approximately = 0.87). Hexavalent chromium sorption by TS decreased with increase in pH, and slightly reduced with increase in ionic strength. Cr(VI) removal by TS seems to be mainly by chemisorption. Desorption of Cr(VI) from Cr(VI) laden TS was quite less by distilled water and HCl. Whereas with NaOH, maximum desorption achieved was about 15.3%. When TS was used in downflow column mode, Cr(VI) removal was quite good but head loss increased as the run progressed and was stopped after 200 h.

  2. Cr(VI) uptake mechanism of Bacillus cereus.

    Science.gov (United States)

    Chen, Zhi; Huang, Zhipeng; Cheng, Yangjian; Pan, Danmei; Pan, Xiaohong; Yu, Meijuan; Pan, Zhiyun; Lin, Zhang; Guan, Xiong; Wu, Ziyu

    2012-04-01

    In this study, we investigated the Cr(VI) uptake mechanism in an indigenous Cr(VI)-tolerant bacterial strain -Bacillus cereus through batch and microscopic experiments. We found that both the cells and the supernatant collected from B. cereus cultivation could reduce Cr(VI). The valence state analysis revealed the complete transformation from Cr(VI) into Cr(III) by living B. cereus. Further X-ray absorption fine structure and Fourier transform infrared analyses showed that the reduced Cr(III) was coordinated with carboxyl and amido functional groups from either the cells or supernatant. Scanning electron microscopy and atomic force microscopy observation showed that noticeable Cr(III) precipitates were accumulated on bacterial surfaces. However, Cr(III) could also be detected in bacterial inner portions by using transmission electron microscopy thin section analysis coupled with energy dispersive X-ray spectroscopy. Through quantitative analysis of chromium distribution, we determined the binding ratio of Cr(III) in supernatant, cell debris and cytoplasm as 22%, 54% and 24%, respectively. Finally, we further discussed the role of bacterium-origin soluble organic molecules to the remediation of Cr(VI) pollutants.

  3. The distribution and kinematics of interstellar O~{\\small VI} in the Milky Way}

    CERN Document Server

    Sarma, Rathin; Murthy, Jayanta; Sarma, Jayanta K

    2016-01-01

    We present the results of a survey of interstellar O~{\\small VI} absorption in the Milky Way (MW) towards {69} stars in the Large Magellanic Cloud (LMC) obtained with the \\textit{Far Ultraviolet Spectroscopic Explorer (FUSE)}. The integrated MW O~{\\small VI} column densities log N(O~{\\small VI}) are in the range from 13.68 to 14.73 with a mean of {14.26$_{-0.09}^{+0.07}$} atoms cm$^{-2}$. The O~{\\small VI} exponential scale height is found to be {2.28$\\pm$1.06} kpc. The O~{\\small VI} column density correlates with the Doppler parameter $\\it b$. The O~{\\small VI} velocity dispersion ranges from {14.0 to 91.6 with an average value of 62.7 km s$^{-1}$}. These high values of velocity dispersion reveal the effect of turbulence, multiple velocity components and collision on broad O~{\\small VI} profiles. There is a significant variation of O~{\\small VI} column density on all scales studied {(0.0025$\\degr$ - 6.35$\\degr$)}. The smallest scale for which O~{\\small VI} column density variations has been found is {$\\bigtr...

  4. Identification of Type VI Collagen Synthesizing Cells in Human Diabetic Glomerulosclerosis Using Renal Biopsy Sections

    Directory of Open Access Journals (Sweden)

    Mohammed Shawkat Razzaque

    1997-01-01

    Full Text Available Although the role of extracellular matrices in the development of glomerulosclerosis has been discussed widely, the cellular origin of type VI collagen in diabetic nephropathy (DN has remained relatively unexplored. This study reports the distribution and cellular origin of type VI collagen in DN. Type VI collagen‐specific oligonucleotide probes and monoclonal antibody were used to assess the relative expression of mRNA for \\alpha1 (VI chain and its translated protein in paraffin‐embedded renal biopsy sections of DN. By immunohistochemistry, compared to the control, increased deposition of type VI collagen was noted in the diffuse and nodular lesions of diabetic glomeruli. For cellular localization of type VI collagen mRNA, paraffin‐embedded renal sections of the control and DN were hybridized in situ with digoxigenin (Dig‐labeled antisense oligo‐DNA probe complementary to a part of \\alpha1 (VI mRNA. In comparison to the control kidney sections, increased numbers of intraglomerular cells (both mesangial and epithelial cells were positive for α1 (VI mRNA in renal biopsy sections of DN. From the results, we conclude that overexpression of type VI collagen by intraglomerular cells with its increased deposition might significantly contribute to the glomerulosclerosis found in DN.

  5. Transient groundwater chemistry near a river: Effects on U(VI) transport in laboratory column experiments

    Science.gov (United States)

    Yin, Jun; Haggerty, Roy; Stoliker, Deborah L.; Kent, Douglas B.; Istok, Jonathan D.; Greskowiak, Janek; Zachara, John M.

    2011-01-01

    In the 300 Area of a U(VI)-contaminated aquifer at Hanford, Washington, USA, inorganic carbon and major cations, which have large impacts on U(VI) transport, change on an hourly and seasonal basis near the Columbia River. Batch and column experiments were conducted to investigate the factors controlling U(VI) adsorption/desorption by changing chemical conditions over time. Low alkalinity and low Ca concentrations (Columbia River water) enhanced adsorption and reduced aqueous concentrations. Conversely, high alkalinity and high Ca concentrations (Hanford groundwater) reduced adsorption and increased aqueous concentrations of U(VI). An equilibrium surface complexation model calibrated using laboratory batch experiments accounted for the decrease in U(VI) adsorption observed with increasing (bi)carbonate concentrations and other aqueous chemical conditions. In the column experiment, alternating pulses of river and groundwater caused swings in aqueous U(VI) concentration. A multispecies multirate surface complexation reactive transport model simulated most of the major U(VI) changes in two column experiments. The modeling results also indicated that U(VI) transport in the studied sediment could be simulated by using a single kinetic rate without loss of accuracy in the simulations. Moreover, the capability of the model to predict U(VI) transport in Hanford groundwater under transient chemical conditions depends significantly on the knowledge of real-time change of local groundwater chemistry.

  6. Condições de serventia de estradas não-pavimentadas: estudo de caso aplicado às vias do município de Viçosa, Estado de Minas Gerais, Brasil = Serviceability of unpaved roads: a case study applied to net road from Viçosa, Minas Gerais

    Directory of Open Access Journals (Sweden)

    Taciano Oliveira da Silva

    2011-04-01

    Full Text Available Este artigo apresenta a adaptação do método de classificação de estradas nãopavimentadas proposto por Eaton às condições encontradas em rodovias vicinais do município de Viçosa, Estado de Minas Gerais, considerando a sua potencialidade como ferramenta de suporte à gerência destas vias. Este estudo foi desenvolvido a partir deavaliações objetiva, realizada com o emprego de uma escala de notas, e subjetiva, em obediência à metodologia de Eaton, que foram conduzidas por uma equipe treinada previamente que executou inspeções de campo, atribuindo notas a 20 unidades amostrais, possuindo cada uma delas 50 m de comprimento e representativas de 10 trechos analisados de vias não-pavimentadas. A análise dos dados desta pesquisa possibilitou concluir que: (i não houve correlação entre os resultados das avaliações subjetiva e objetiva, e a aplicação dametodologia de Eaton à gerência de manutenção de vias não-pavimentadas pode não refletir as suas prioridades reais; (ii a avaliação subjetiva do trecho e a avaliação subjetiva do conjunto de suas unidades amostrais são correlatas, indicando ser coerente o emprego deste procedimento.This paper addresses the adaptation of the method of classification of unpaved roads developed by Eaton to the field conditions of local roads from the city of Viçosa, Minas Gerais State, Brazil, considering its potential as a support tool for the management of these roads. This study was developed encompassing objective evaluation, carried out with the application of a note scale, and subjective evaluation, according to the methodology of Eaton, which were performed by a team that accomplished the field inspections, attributing notes to the 20 sample units, each one 50 meters long andrepresenting 10 analyzed unpaved road segments. Conclusions are as follows: (i it was not observed any correlation between data from the objective and the subjective field evaluations, leading to the conclusion

  7. Vi capsular polysaccharide-protein conjugates for prevention of typhoid fever. Preparation, characterization, and immunogenicity in laboratory animals.

    Science.gov (United States)

    Szu, S C; Stone, A L; Robbins, J D; Schneerson, R; Robbins, J B

    1987-11-01

    The Vi has proven to be a protective antigen in two double masked, controlled clinical trials in areas with high rates of typhoid fever (approximately 1% per annum). In both studies the protective efficacy of the Vi was approximately 70%. Approximately 75% of subjects in these areas responded with a fourfold or greater rise of serum Vi antibodies. In contrast, the Vi elicited a fourfold or greater rise in 95-100% of young adults in France and the United States. Methods were devised, therefore, to synthesize Vi-protein conjugates in order to both enhance the antibody response and confer T-dependent properties to the Vi (and theoretically increase its protective action in populations at high risk for typhoid fever). We settled on a method that used the heterobifunctional crosslinking reagent, N-succinimidyl-3-(2-pyridyldithio)-propionate (SPDP), to bind thiol derivatives of the Vi to proteins. This synthetic scheme was reproducible, provided high yields of Vi-protein conjugates, and was applicable to several medically relevant proteins such as diphtheria and tetanus toxoids. The resultant conjugates were more immunogenic in mice and juvenile Rhesus monkeys than the Vi alone. In contrast to the T-independent properties of the Vi, conjugates of this polysaccharide with several medically relevant proteins induced booster responses in mice and in juvenile Rhesus monkeys. Clinical studies with Vi-protein conjugates are planned. This scheme is also applicable to synthesize protein conjugates with other polysaccharides that have carboxyl functions.

  8. VI. Fünfter Aufzug

    OpenAIRE

    2014-01-01

    1. Erstes Bild (VI) a) Einleitung Demaenetus und Argirippus treten mit Philaenium aus dem Haus und beginnen ein Gelage auf offener Straße (nicht im Innern, durch eine offene Tür für den Zuschauer sichtbar: so Weise, Ussing, Kunst 1919, 156, Webster 1970, 237): siehe 941. Der frivole senex besteht auf Zärtlichkeiten der Hetäre, verlangt sogar von seinem Sohn, sich als heiter gestimmter Zechkumpane zu gerieren. Dieser erkennt Demaenetus’ Rechte an. Der Dialog pointiert nicht nur Demaenetus’ Wan...

  9. Drying Effects on Corrosion Properties of Cr(VI) and Cr(III) Treated Electrogalvanized Steel

    NARCIS (Netherlands)

    Zhang, X.; Van den Bos, C.; Sloof, W.G.; Hovestad, A.; Terryn, H.; De Wit, J.H.W.

    2006-01-01

    Drying effects on corrosion performance of Cr(VI)- and Cr(III)-treated electro-galvanized steel have been studied in NaCl solution using potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). The Cr(VI) and the Cr(III) treated specimens were dried at three different temperatu

  10. Inhibition of corrosion of zinc by Cr(VI)and Cr(III) treatments

    NARCIS (Netherlands)

    Zhang, X.; Bos, C. van den; Hovestad, A.; Terryn, H.; Wit, J.H.W. de

    2007-01-01

    The corrosion behavior of Cr(VI) and Cr(III) treated zinc has been studied using scanning Kelvin probe (SKP), potentiodynamic polarization and elctrochemical impedance spectroscopy (EIS). The Volta potentials measured on the Cr(VI) or the CR(III)-A treated zinc area by SKP in a humid chamber are mor

  11. Chromium(VI) reduction by catechol(amine)s results in DNA cleavage in vitro

    DEFF Research Database (Denmark)

    Pattison, D I; Davies, Michael Jonathan; Levina, A;

    2001-01-01

    ) or 4-tert-butylcatechol (5) do not damage DNA. The Cr(VI)/catechol(amine) reactions have been studied at low added H(2)O(2) concentrations, which lead to enhanced DNA cleavage with 1 and induce DNA cleavage with 4. The Cr(V) and organic intermediates generated by the reactions of Cr(VI) with 1 or 4...

  12. Development of a new Cr(VI)-biosorbent from agricultural biowaste.

    Science.gov (United States)

    Park, Donghee; Lim, Seong-Rin; Yun, Yeoung-Sang; Park, Jong Moon

    2008-12-01

    Among useless but abundant agricultural biowastes such as banana skin, green tea waste, oak leaf, walnut shell, peanut shell and rice husk, in this study, banana skin was screened as the most efficient biomaterial to remove toxic Cr(VI) from aqueous solution. X-ray photoelectron spectroscopy (XPS) study revealed that the mechanism of Cr(VI) biosorption by banana skin was its complete reduction into Cr(III) in both aqueous and solid phases and partial binding of the reduced-Cr(III), in the range of pH 1.5-4 tested. One gram of banana skin could reduce 249.6 (+/-4.2)mg of Cr(VI) at initial pH 1.5. Namely, Cr(VI)-reducing capacity of banana skin was four times higher than that of a common chemical Cr(VI)-reductant, FeSO(4).7H(2)O. To diminish undesirable/serious organic leaching from the biomaterial and to enhance removal efficiency of total Cr, its powder was immobilized within Ca-alginate bead. The developed Cr(VI)-biosorbent could completely reduce toxic Cr(VI) to less toxic Cr(III) and could remove almost of the reduced-Cr(III) from aqueous phase. On the basis of removal mechanisms of Cr(VI) and total Cr by the Cr(VI)-biosorbent, a kinetic model was derived and could be successfully used to predict their removal behaviors in aqueous phase. In conclusion, our Cr(VI)-biosorbent must be a potent candidate to substitute for chemical reductants as well as adsorbents for treating Cr(VI)-bearing wastewaters.

  13. Physical activity does not influence the effect of antioxidant supplementation at nutritional doses on the incidence of impaired fasting glucose: a 7.5 year post-hoc analysis from the SU.VI.MAX study.

    Science.gov (United States)

    Fezeu, L; Henegar, A; Kesse-Guyot, E; Julia, C; Galan, P; Hercberg, S; Ristow, M; Czernichow, S

    2010-10-01

    Supplementation with high doses of antioxidant vitamins prevents the insulin-sensitizing effects of physical exercise. However, little is known whether antioxidant supplementation affects the incidence of impaired fasting glucose (IFG). Data from 8938 subjects included in a randomized controlled trial on supplementation with antioxidants vitamins and trace elements at nutritional doses (SU.VI.MAX) were used to examine the effects of antioxidants on incident IFG after 7.5 years of follow-up, with and without stratification for daily physical exercise. The odds-ratio (95% CI) for developing an IFG among study participants receiving antioxidant supplementation was 1.34 (0.90-1.97) (p=0.33), in comparison to placebo. This risk did not vary significantly according to physical activity level (p for homogeneity=0.10). Supplementation with trace elements and antioxidants at nutritional doses apparently does not affect the incidence of IFG irrespective of self-reported physical exercise habits.

  14. Removal of Cr(VI from aqueous solution using Bacillus subtilis, Pseudomonas aeruginosa and Enterobacter cloacae

    Directory of Open Access Journals (Sweden)

    P. Sethuraman,

    2010-06-01

    Full Text Available The objective of this study is to investigate the removal efficiency of Cr(VI by Bacillus subtilis, Pseudomonas aeruginosa and Enterobacter cloacae from aqueous solution under different process conditions. Batch mode experiments were carried out as a function of solution pH, biosorbent dosage, Cr(VI concentration and contact time.The FT-IR spectra and SEM analysis of the biosorbent were recorded to analyse the number and position of the functional groups available for the binding of Cr(VI ions and to study the morphology of biosorbent. The batch isothermal equilibrium data were analyzed with Freundlich and Langmuir isotherm models. The kinetic models were examined with pseudo first order and pseudo second order kinetics. The results revealed that the Cr(VI is considerably adsorbed on bacterial biomass and it could be an economical method for the removal of Cr(VI from aqueous solution.

  15. 29 CFR 1915.1026 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... system dysfunction; any history of asthma, dermatitis, skin ulceration, or nasal septum perforation; and... is present or is likely to be present from skin or eye contact with chromium (VI), the employer shall... cleaned in a manner that minimizes skin or eye contact with chromium (VI) and effectively prevents...

  16. 29 CFR 1926.1126 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... system dysfunction; any history of asthma, dermatitis, skin ulceration, or nasal septum perforation; and... is present or is likely to be present from skin or eye contact with chromium (VI), the employer shall... cleaned in a manner that minimizes skin or eye contact with chromium (VI) and effectively prevents...

  17. X-ray diffraction study of epitaxial heterostructures of II-VI CdTe and ZnTe semiconductors; Etude par diffraction de rayons X d`heterostructures epitaxiees a base des semi-conducteurs II-VI CdTe et ZnTe

    Energy Technology Data Exchange (ETDEWEB)

    Bouchet-Boudet, N.

    1996-10-07

    This work deals with the structural study of II-VI semiconductor (CdTe and ZnTe) heterostructures by X-ray diffraction and reflectivity. These heterostructures have a high lattice parameter misfit and are grown by Molecular Beam Epitaxy. Two main subjects are developed: the characterization of ZnTe wires, grown by step propagation on a CdTe (001) vicinal surface, and the study of the vertical correlations in Cd{sub 0.8}Zn{sub 0.2}Te / CdTe superlattices and superlattices made of ZnTe fractional layers spaced by CdTe. The growth of organised system is up to date; its aim is to realize quantum boxes (or wires) superlattices which are laterally and vertically ordered. The deformation along the growth axis induced by a ZnTe fractional layer inserted in a CdTe matrix is modelled, in the kinematical approximation, to reproduce the reflectivity measured around the substrate (004) Bragg peak. The lateral periodicity of the wires, deposited on a vicinal surface is a new and difficult subject. Some results are obtained on a vertical superlattice grown on a 1 deg. mis-cut surface. The in-plane and out-of-plane correlation lengths of a Cd{sub 0.8}Zn{sub 0.2}Te / CdTe superlattice are deduced from the diffused scattered intensity measured at grazing incidence. The calculations are made within the `distorted Wave Born Approximation`. The vertical correlation in ZnTe boxes (or wines) superlattices can be measured around Bragg peaks. It is twice bigger in a superlattice grown on a 2 deg. mis-cut substrate than a nominal one. (author). 74 refs.

  18. Forensic investigation of a chromium(VI) groundwater plume in Thiva, Greece

    Energy Technology Data Exchange (ETDEWEB)

    Panagiotakis, I. [National Technical Univ. of Athens, Zografou (Greece); Dermatas, D. [National Technical Univ. of Athens, Zografou (Greece); Vatseris, C. [Intergeo-Environmental Technology Ltd., Thessaloniki (Greece); Chrysochoou, M. [Univ. of Connecticut, Storrs, CT (United States); Papassiopi, N. [National Technical Univ. of Athens, Zografou (Greece); Xenidis, A. [National Technical Univ. of Athens, Zografou (Greece); Vaxevanidou, K. [National Technical Univ. of Athens, Zografou (Greece)

    2015-01-01

    We conducted a forensic investigation with the aim of decoupling the contribution of geogenic and anthropogenic Cr(VI) sources in the wider area of Thiva. Groundwater and topsoil samples were collected from two Cr(VI) groundwater plumes of 160 μg/L and 75 μg/L. A series of evidence support the view that the origin of Cr(VI) detected in groundwater is mainly geogenic. These are: (a) the presence of Cr in topsoil of the wider area, (b) the moderate Cr(VI) groundwater concentrations, (c) the high Ni levels within the Cr(VI) plumes, (d) the predominance of Mn(IV), which is a prerequisite for Cr(III) oxidation to Cr(VI), and (e) the absence of co-contaminants. This study also revealed that, although both Cr(VI) plumes are clearly of geogenic origin, the plume with the elevated Cr(VI) values, in the north of Thiva town, exhibits also an anthropogenic component, which can potentially be attributed to the alkaline environment associated with the old uncontrolled landfill of Thiva and the industrial cluster located in this area.

  19. [Safety and immunogenecity of a vaccine of polyssacharide Vi from Salmonella typhi in Cuban youths].

    Science.gov (United States)

    Azze, Rolando Felipe Ochoa; Suárez, Idalia Morelia Baró; Rodríguez, Juan Carlos Martínez; Sosa, Mayelin Mirabal; del Río, Marlene Isabel Armesto; Alvarez, Francisco Domínguez

    2003-01-01

    A randomized, controlled and double-blind study was conducted in young adults aged 18-20 aimed at evaluating the reactogenecity and immunogenecity of vaz-TyVi, a vaccine of polyssacharide Vi from Salmonella typhi. They were distributed into 3 groups: immunized with a dose of Vax-TyVi (Finlay Institute), TYPHIM Vi (Pasteur-Mérieux) or vax-TET (tetanic toxoid). Serum samples were taken before and 21 days after immunization. The immunogenecity was evaluated in 323 volunteers by an indirect ELISA. The seroconversion of those receiving vax-TyVi was 81.97% and 65.05 % for TYPHIM Vi. The postvaccine mean geometric titers were 7.41 U/mL (5.92-9.27 U/mL) and 5.41 U/mL (4.35-6.72 U/mL), respectively. The seroconversion with vax-TET was 0%. The reactogenecity of both polysaccharide vaccines was low. It was concluded that the immunogenecity of vax-TyVi was not lower than that of TYPHIM Vi and that its reactogenecity was similar.

  20. Adsorption of Cr(VI) from synthetic solutions and electroplating wastewaters on amorphous aluminium oxide.

    Science.gov (United States)

    Alvarez-Ayuso, E; García-Sánchez, A; Querol, X

    2007-04-02

    The adsorption behaviour of amorphous aluminium oxide was studied with respect to Cr(VI) in order to consider its application to purify electroplating wastewaters. A batch method was employed using Cr(VI) concentrations ranged from 10 to 200mg/l. The Langmuir model was found to describe the adsorption process well, offering a maximum adsorption capacity of 78.1mg/g. The effect of ionic strength (0-0.1M KNO(3)), pH (3-9) and competitive solutes (molar ratio [Cr(VI)]/[SO(4)(2-)]=1 and 100) on the retention process was evaluated. Cr(VI) adsorption on amorphous aluminium oxide appeared to be dependent on ionic strength with a more pronounced effect in acid conditions. Conversely, adsorption was not affected by pH in acid medium, but decreased when pH sifted to alkaline values. The presence of SO(4)(2-) greatly reduced Cr(VI) removal across the entire pH range when both solutes were present in similar concentrations. Amorphous aluminium oxide also showed a high adsorption capacity when used in the purification of Cr(VI) electroplating wastewaters. The adsorbent doses required to attain more than 90% of Cr(VI) removal varied between 1 and 5 g/l depending on Cr(VI) concentration in wastewaters.

  1. Inhibition of nitrate reduction by chromium (VI) in anaerobic soil microcosms

    Energy Technology Data Exchange (ETDEWEB)

    Kourtev, P. S.; Nakatsu, C. H.; Konopka, Allan

    2009-10-01

    Chromium (VI) is often found as a co-contaminant at sites polluted with organic compounds. We used microcosms amended with glucose or protein, nitrate and increasing concentrations of chromium to study nitrate reduction in Cr(VI) polluted soils. Organic carbon stimulated bacterial activity, but the addition of Cr(VI) caused a lag and then slower rates 5 of CO2 accumulation. Nitrate reduction only occurred after Cr(VI) had been reduced. Bacterial activity was again inhibited when Cr(VI) was added a second time; thus not all Cr-sensitive bacteria were removed in the first phase. Glucose and protein selected for relatively similar bacterial communities, as assayed by PCR-DGGE of the 16S rRNA gene; this selection was modified by the addition of 10 Cr(VI). Cr-resistant bacteria isolated from microcosms were closely related to members of Bacillus, Enterococcus and Propionibacterium sp. Our results indicate that carbon utilization and nitrate reduction in these soils in the presence of Cr(VI) are contingent upon the reduction of the added heavy metal by a limited subset of the bacterial community. The amount of Cr(VI) required to inhibit nitrate reduction was 10-fold less than for aerobic catabolism of the same 15 substrate. We hypothesize that the resistance level of a microbial process is directly related to the diversity of microbes capable of conducting it.

  2. Modelling Cr(VI) removal by a combined carbon-activated sludge system

    Energy Technology Data Exchange (ETDEWEB)

    Orozco, A. Micaela Ferro [Centro de Investigacion y Desarrollo en Criotecnologia de Alimentos (CIDCA), CONICET, Fac. de Cs. Exactas, UNLP. 47 y 116 (B1900AJJ), La Plata (Argentina); Contreras, Edgardo M. [Centro de Investigacion y Desarrollo en Criotecnologia de Alimentos (CIDCA), CONICET, Fac. de Cs. Exactas, UNLP. 47 y 116 (B1900AJJ), La Plata (Argentina)], E-mail: econtrer@quimica.unlp.edu.ar; Zaritzky, Noemi E. [Centro de Investigacion y Desarrollo en Criotecnologia de Alimentos (CIDCA), CONICET, Fac. de Cs. Exactas, UNLP. 47 y 116 (B1900AJJ), La Plata (Argentina); Fac. de Ingenieria, UNLP. 47 y 1 (B1900AJJ), La Plata (Argentina)

    2008-01-15

    The combined carbon-activated sludge process has been proposed as an alternative to protect the biomass against toxic substances in wastewaters; however, the information about the effect of powdered-activated carbon (PAC) addition in activated sludge reactors for the treatment of wastewaters containing Cr(VI) is limited. The objectives of the present study were: (a) to evaluate the removal of hexavalent chromium by (i) activated sludge microorganisms in aerobic batch reactors, (ii) powdered-activated carbon, and (iii) the combined action of powdered-activated carbon and biomass; (b) to propose mathematical models that interpret the experimental results. Different Cr(VI) removal systems were tested: (S1) biomass (activated sludge), (S2) PAC, and (S3) the combined activated carbon-biomass system. A Monod-based mathematical model was used to describe the kinetics of Cr(VI) removal in the system S1. A first-order kinetics with respect to Cr(VI) and PAC respectively, was proposed to model the removal of Cr(VI) in the system S2. Cr(VI) removal in the combined carbon-biomass system (S3) was faster than both Cr(VI) removal using PAC or activated sludge individually. Results showed that the removal of Cr(VI) using the activated carbon-biomass system (S3) was adequately described by combining the kinetic equations proposed for the systems S1 and S2.

  3. Single-step synthesis of magnetic chitosan composites and application for chromate (Cr(VI)) removal

    Institute of Scientific and Technical Information of China (English)

    杨卫春; 唐琼芝; 董舒宇; 柴立元; 王海鹰

    2016-01-01

    Magnetic chitosan composites (Fe3O4@chitosan) were synthesized in one single-step, characterized and applied in Cr(VI) removal from water. With the increase of loading proportion of chitosan, Cr(VI) adsorption capacity of Fe3O4@chitosan composites increased from 10.771 to 21.040 mg/g. The optimum adsorption capacities of Cr(VI) on Fe3O4@chitosan-3 were found in a pH range of 3.0−5.0. Kinetic study results show that the adsorption process follows pseudo-second-order model, indicating that the rate-limiting step in the adsorption of Cr(VI) involves chemisorptions. Moreover, FT-IR spectra analysis confirms that the amine and hydroxyl groups of chitosan are predominantly responsible for binding. Results from this work demonstrate that the prepared Fe3O4@chitosan composites possess great potential in Cr(VI) removal from contaminated water.

  4. Chemistry of the Colloidal Group II-VI Nanocrystal Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Haitao [Univ. of California, Berkeley, CA (United States)

    2007-05-17

    In the last two decades, the field of nanoscience andnanotechnology has witnessed tremendous advancement in the synthesis andapplication of group II-VI colloidal nanocrystals. The synthesis based onhigh temperature decomposition of organometallic precursors has becomeone of the most successful methods of making group II-VI colloidalnanocrystals. This methodis first demonstrated by Bawendi and coworkersin 1993 to prepare cadmium chalcogenide colloidal quantum dots and laterextended by others to prepare other group II-VI quantum dots as well asanisotropic shaped colloidal nanocrystals, such as nanorod and tetrapod.This dissertation focuses on the chemistry of this type of nanocrystalsynthesis. The synthesis of group II-VI nanocrystals was studied bycharacterizing the molecular structures of the precursors and productsand following their time evolution in the synthesis. Based on theseresults, a mechanism was proposed to account for the 2 reaction betweenthe precursors that presumably produces monomer for the growth ofnanocrystals. Theoretical study based on density functional theorycalculations revealed the detailed free energy landscape of the precursordecomposition and monomerformation pathway. Based on the proposedreaction mechanism, a new synthetic method was designed that uses wateras a novel reagent to control the diameter and the aspect ratio of CdSeand CdS nanorods.

  5. BIOADSORPTION USING COMPOST: AN ALTERNATIVE FOR REMOVAL OF CHROMIUM (VI FROM AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    Claudia Vargas,

    2012-05-01

    Full Text Available The removal of Cr(VI from aqueous solutions was studied using a compost generated from carnation flowers waste. The highest percentage of removal achieved (ca. 99 % was obtained at pH 2.0, using a 10 mg L-1 of Cr(VI solution, a dose of 10 g L-1 of compost, and with an equilibrium time of 3 hours. Under these conditions, the kinetics and adsorption isotherm were examined varying the initial Cr(VI concentration from 15 to 200 mg L-1. The maximum sorption capacity at equilibrium (Qm, from the Langmuir model, was found to be 6.25 mg g-1. The evaluation of Cr(VI removal at pH 2.0 showed a second order kinetics and showed that the process mechanism can be modeled by the “adsorption-coupled reduction” hypothesis. Also, the monitoring of Cr(VI and total Cr in aqueous solutions showed that Cr(VI and total Cr were removed from solution, and that part of the Cr(III was retained on the compost. According to the results, the removal of Cr(VI with the assayed compost can be explained by the following steps: (i adsorption of Cr(VI species onto compost, (ii Cr(VI reduction to Cr(III, and (iii adsorption of part of Cr(III on the compost. Thus, this study suggests that the carnation flower waste compost can be used as a remediation system for water contaminated with Cr(VI.

  6. Settleability and characteristics of ferrate(VI)-induced particles in advanced wastewater treatment.

    Science.gov (United States)

    Zheng, Lei; Deng, Yang

    2016-04-15

    Ferrate(VI) as an emerging water treatment agent has recently recaptured interests for advanced wastewater treatment. A large number of studies were published to report ferrate(VI)-driven oxidation for various water contaminants. In contrast, very few efforts were made to characterize ferrate(VI) resultant particles in water and wastewater. In this study, jar tests were performed to examine the settleability and characteristics of ferrate(VI)-induced iron oxide particles, particularly the non-settable fraction of these particles, after ferrate(VI) reduction in a biologically treated municipal wastewater. The particle settleability was evaluated through the measurement of turbidity and particulate iron concentration in the supernatant with the settling time. Results showed that a majority of ferrate(VI)-induced iron oxide aggregates remained suspended and caused an increased turbidity. For example, at a Fe(VI) dose of 5.0 mg/L and pH 7.50, 82% of the added iron remained in the supernatant and the turbidity was 8.97 NTU against the untreated sample turbidity (2.33 NTU) after 72-h settling. The poor settling property of these particles suggested that coagulation and flocculation did not perform well in the ferrate(VI) treatment. Particle size analysis and transmission electron microscopy (TEM) revealed that nano-scale particles were produced after ferrate(VI) decomposition, and gradually aggregated to form micro-scale larger particles in the secondary effluent. Zeta potentials of the non-settable ferrate(VI) resultant aggregates varied between -7.36 and -8.01 mV at pH 7.50 during the 72-h settling. The negative surface charges made the aggregates to be relatively stable in the wastewater matrix.

  7. Loss of cargo binding in the human myosin VI deafness mutant (R1166X) leads to increased actin filament binding.

    Science.gov (United States)

    Arden, Susan D; Tumbarello, David A; Butt, Tariq; Kendrick-Jones, John; Buss, Folma

    2016-10-01

    Mutations in myosin VI have been associated with autosomal-recessive (DFNB37) and autosomal-dominant (DFNA22) deafness in humans. Here, we characterise an myosin VI nonsense mutation (R1166X) that was identified in a family with hereditary hearing loss in Pakistan. This mutation leads to the deletion of the C-terminal 120 amino acids of the myosin VI cargo-binding domain, which includes the WWY-binding motif for the adaptor proteins LMTK2, Tom1 as well as Dab2. Interestingly, compromising myosin VI vesicle-binding ability by expressing myosin VI with the R1166X mutation or with single point mutations in the adaptor-binding sites leads to increased F-actin binding of this myosin in vitro and in vivo As our results highlight the importance of cargo attachment for regulating actin binding to the motor domain, we perform a detailed characterisation of adaptor protein binding and identify single amino acids within myosin VI required for binding to cargo adaptors. We not only show that the adaptor proteins can directly interact with the cargo-binding tail of myosin VI, but our in vitro studies also suggest that multiple adaptor proteins can bind simultaneously to non-overlapping sites in the myosin VI tail. In conclusion, our characterisation of the human myosin VI deafness mutant (R1166X) suggests that defects in cargo binding may leave myosin VI in a primed/activated state with an increased actin-binding ability.

  8. Modeling of kinetics of Cr(VI) sorption onto grape stalk waste in a stirred batch reactor.

    Science.gov (United States)

    Escudero, Carlos; Fiol, Nuria; Poch, Jordi; Villaescusa, Isabel

    2009-10-15

    Recently, Cr(VI) removal by grape stalks has been postulated to follow two mechanisms, adsorption and reduction to trivalent chromium. Nevertheless, the rate at which both processes take place and the possible simultaneity of both processes has not been investigated. In this work, kinetics of Cr(VI) sorption onto grape stalk waste has been studied. Experiments were carried out at different temperatures but at a constant pH (3+/-0.1) in a stirred batch reactor. Results showed that three steps take place in the process of Cr(VI) sorption onto grape stalk waste: Cr(VI) sorption, Cr(VI) reduction to Cr(III) and the adsorption of the formed Cr(III). Taking into account the evidences above mentioned, a model has been developed to predict Cr(VI) sorption on grape stalks on the basis of (i) irreversible reduction of Cr(VI) to Cr(III) reaction, whose reaction rate is assumed to be proportional to the Cr(VI) concentration in solution and (ii) adsorption and desorption of Cr(VI) and formed Cr(III) assuming that all the processes follow Langmuir type kinetics. The proposed model fits successfully the kinetic data obtained at different temperatures and describes the kinetics profile of total, hexavalent and trivalent chromium. The proposed model would be helpful for researchers in the field of Cr(VI) biosorption to design and predict the performance of sorption processes.

  9. Removal of Ni (II and Cr (VI ions from aqueous solution using by-product from the production of aluminium

    Directory of Open Access Journals (Sweden)

    A. Štrkalj

    2015-01-01

    Full Text Available In this paper comparative adsorption equilibrium studies of Ni (II and Cr (VI ions on commercial activated carbon (CAC and carbon anode dust (CAD are presented. The equilibrium studies confirmed that Freundlich model best describes the adsorption systems CAC + Cr (VI, CAD + Ni (II and CAD + Cr (VI. The Dubinin-Radushevich isotherm can be used to describe system CAC + Ni (II.The results indicate that the intra-particle diffusion model is applicable for adsorption system CAC + Cr (VI and pseudo-second kinetic model is applicable for adsorption systems CAC + Ni (II, CAD + Cr (VI and CAD + Ni (II. Obtained results indicate that adsorption of Ni (II and Cr (VI ions on CAC and CAD depends on the temperature.

  10. Cr(VI) occurrence and geochemistry in water from public-supply wells in California

    Science.gov (United States)

    Izbicki, John; Wright, Michael; Seymour, Whitney A.; McCleskey, R. Blaine; Fram, Miranda S.; Belitz, Kenneth; Esser, Bradley K.

    2015-01-01

    Hexavalent chromium, Cr(VI), in 918 wells sampled throughout California between 2004 and 2012 by the Groundwater Ambient Monitoring and Assessment-Priority Basin Project (GAMA-PBP) ranged from less than the study reporting limit of 1 microgram per liter (μg/L) to 32 μg/L. Statewide, Cr(VI) was reported in 31 percent of wells and equaled or exceeded the recently established (2014) California Maximum Contaminant Level (MCL) for Cr(VI) of 10 μg/L in 4 percent of wells. Cr(VI) data collected for regulatory purposes overestimated Cr(VI) occurrence compared to spatially-distributed GAMA-PBP data. Ninety percent of chromium was present as Cr(VI), which was detected more frequently and at higher concentrations in alkaline (pH ≥ 8), oxic water; and more frequently in agricultural and urban land uses compared to native land uses. Chemical, isotopic (tritium and carbon-14), and noble-gas data show high Cr(VI) in water from wells in alluvial aquifers in the southern California deserts result from long groundwater-residence times and geochemical reactions such as silicate weathering that increase pH, while oxic conditions persist. High Cr(VI) in water from wells in alluvial aquifers along the west-side of the Central Valley results from high-chromium in source rock eroded to form those aquifers, and areal recharge processes (including irrigation return) that can mobilize chromium from the unsaturated zone. Cr(VI) co-occurred with oxyanions having similar chemistry, including vanadium, selenium, and uranium. Cr(VI) was positively correlated with nitrate, consistent with increased concentrations in areas of agricultural land use and mobilization of chromium from the unsaturated zone by irrigation return.

  11. 微生物治理碱性含铬废水的试验研究%Experimental study on microbial treatment of alkaline wastewater containing chromium(Cr(VI))

    Institute of Scientific and Technical Information of China (English)

    柴立元; 龙腾发; 唐宁; 庄明龙; 闵小波

    2005-01-01

    用从铬渣堆埋场附近的污泥中分离到的无色杆菌属C-1菌株, 对碱性含铬废水进行生物处理, 研究了该菌的生长条件, 并探讨了温度、pH值、Cr(VI)初始浓度及作用时间等因素对Cr(VI)还原的影响. 研究结果表明: C-1菌株适应碱性环境, 对Cr(VI)具有较强的还原能力;在有氧、pH=10.30和温度为32 ℃的条件下, 含Cr(VI)1 570.0 mg/L的废水经微生物处理16 h后Cr(VI)质量浓度降为0.6 mg/L;处理后的沉淀物中铬以非晶态存在, 其中总铬含量为21.44%, Cr(VI)为痕量.

  12. Probing the interaction of U(vi) with phosphonate-functionalized mesoporous silica using solid-state NMR spectroscopy.

    Science.gov (United States)

    Uribe, Eva C; Mason, Harris E; Shusterman, Jennifer A; Bruchet, Anthony; Nitsche, Heino

    2016-06-21

    The fundamental interaction of U(vi) with diethylphosphatoethyl triethoxysilane functionalized SBA-15 mesoporous silica is studied by macroscopic batch experiments and solid-state NMR spectroscopy. DPTS-functionalized silica has been shown to extract U(vi) from nitric acid solutions at or above pH 3. Extraction is dependent on pH and ionic strength. Single-pulse (31)P NMR on U(vi) contacted samples revealed that U(vi) only interacts with a fraction of the ligands present on the surface. At pH 4 the U(vi) extraction capacity of the material is limited to 27-37% of the theoretical capacity, based on ligand loading. We combined single pulse (31)P NMR on U(vi)-contacted samples with batch studies to measure a ligand-to-metal ratio of approximately 2 : 1 at pH 3 and 4. Batch studies and cross-polarization NMR measurements reveal that U(vi) binds to deprotonated phosphonate and/or silanol sites. We use (31)P-(31)P DQ-DRENAR NMR studies to compare the average dipolar coupling between phosphorus spins for both U(vi)-complexed and non-complexed ligand environments. These measurements reveal that U(vi) extraction is not limited by inadequate surface distribution of ligands, but rather by low stability of the surface phosphonate complex.

  13. Bioaccumulation of U(VI) by Sulfolobus acidocaldarius under moderate acidic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Reitz, T.; Merroun, M.L.; Rossberg, A.; Steudtner, R.; Selenska-Pobell, S. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany). Inst. of Radiochemistry

    2011-07-01

    U(VI) accumulation by the acidothermophilic archaeon Sulfolobus acidocaldarius at a moderate acidic pH of 4.5 was investigated. This pH value is relevant for some heavy metal and uranium polluted environments where populations of S. acidocaldarius were found to persist. We demonstrate that U(VI) is rapidly complexed by the archaeal cells. A combination of X-ray absorption spectroscopy and time-resolved laser-induced fluorescence spectroscopy revealed that at pH 4.5 organic phosphate and carboxylic groups are involved in the U(VI) complexation. These results are in contrast to those published for most bacteria which at this pH precipitate U(VI) mainly in inorganic uranyl phosphate phases. As demonstrated by TEM only a limited part of the added U(VI) was biomineralized extracellularly in the case of the studied archaeon. Most of the U(VI) accumulates were localized in a form of intracellular deposits which were associated with the inner side of the cytoplasma membrane. Observed differences in U(VI) bioaccumulation between the studied archaeon and bacteria can be explained by the significant differences in their cell wall structures as well as by their different physiological characteristics. (orig.)

  14. ViSIT: Visitor Survey Information Tool

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — ViSIT is an interactive web tool created by USGS to visualize the data collected as part of the National Wildlife Refuge Visitor Survey. The national survey was...

  15. 77 FR 52116 - Title VI; Final Circular

    Science.gov (United States)

    2012-08-28

    .... Department of Justice advised Federal agencies in late 2001, ``although Sandoval foreclosed private judicial.... Recipients will be required to submit, with the Title VI Program, a copy of the Board resolution,...

  16. Rheology of water ices V and VI

    Science.gov (United States)

    Durham, W.B.; Stern, L.A.; Kirby, S.H.

    1996-01-01

    We have measured the mechanical strength (??) of pure water ices V and VI under steady state deformation conditions. Constant displacement rate compressional tests were conducted in a gas apparatus at confining pressures from 400 250 K. Ices V and VI are thus Theologically distinct but by coincidence have approximately the same strength under the conditions chosen for these experiments. To avoid misidentification, these tests are therefore accompanied by careful observations of the occurrences and characteristics of phase changes. One sample each of ice V and VI was quenched at pressure to metastably retain the high-pressure phase and the acquired deformation microstructures; X ray diffraction analysis of these samples confirmed the phase identification. Surface replicas of the deformed and quenched samples suggest that ice V probably deforms largely by dislocation creep, while ice VI deforms by a more complicated process involving substantial grain size reduction through recrystallization.

  17. Influence of soil minerals on chromium(VI reduction by sulfide under anoxic conditions

    Directory of Open Access Journals (Sweden)

    Kim Chulsung

    2007-04-01

    Full Text Available Abstract The effects of soil minerals on chromate (CrVIO42-, noted as Cr(VI reduction by sulfide were investigated in the pH range of 7.67 to 9.07 under the anoxic condition. The examined minerals included montmorillonite (Swy-2, illite (IMt-2, kaolinite (KGa-2, aluminum oxide (γ-Al2O3, titanium oxide (TiO2, P-25, primarily anatase, and silica (SiO2. Based on their effects on Cr(VI reduction, these minerals were categorized into three groups: (i minerals catalyzing Cr(VI reduction – illite; (ii minerals with no effect – Al2O3; and (iii minerals inhibiting Cr(VI reduction- kaolinite, montmorillonite, SiO2 and TiO2 . The catalysis of illite was attributed primarily to the low concentration of iron solubilized from the mineral, which could accelerate Cr(VI reduction by shuttling electrons from sulfide to Cr(VI. Additionally, elemental sulfur produced as the primary product of sulfide oxidation could further catalyze Cr(VI reduction in the heterogeneous system. Previous studies have shown that adsorption of sulfide onto elemental sulfur nanoparticles could greatly increase sulfide reactivity towards Cr(VI reduction. Consequently, the observed rate constant, kobs, increased with increasing amounts of both iron solubilized from illite and elemental sulfur produced during the reaction. The catalysis of iron, however, was found to be blocked by phenanthroline, a strong complexing agent for ferrous iron. In this case, the overall reaction rate at the initial stage of reaction was pseudo first order with respect to Cr(VI, i.e., the reaction kinetics was similar to that in the homogeneous system, because elemental sulfur exerted no effect at the initial stage prior to accumulation of elemental sulfur nanoparticles. In the suspension of kaolinite, which belonged to group (iii, an inhibitive effect to Cr(VI reduction was observed and subsequently examined in more details. The inhibition was due to the sorption of elemental sulfur onto kaolinite, which

  18. As(V)/Cr(VI) pollution control in soils, hemp waste, and other by-products: competitive sorption trials.

    Science.gov (United States)

    Quintáns-Fondo, Ana; Ferreira-Coelho, Gustavo; Paradelo-Núñez, Remigio; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel; Fernández-Sanjurjo, María José; Álvarez-Rodríguez, Esperanza; Núñez-Delgado, Avelino

    2016-10-01

    We study As(V)/Cr(VI) competitive sorption on a forest soil, a vineyard soil, pyritic material, mussel shell, pine bark, oak ash, and hemp waste, adding variable As(V) and Cr(VI) concentrations or displacing each pollutant with the same concentration of the other. When using variable concentrations, As(V) showed more affinity than Cr(VI) for sorption sites on most materials (sorption up to >84 % on oak ash and pyritic material). The only exception was pine bark, with clearly higher Cr(VI) sorption (>90 %) for any Cr(VI)/As(V) concentration added. Regarding the displacement experiments, when As(V) was added and reached sorption equilibrium, the subsequent addition of equal Cr(VI) concentration did not cause relevant As displacement from oak ash and pyritic material, indicating strong As bindings, and/or low competitive effects. When Cr(VI) was added and reached sorption equilibrium, the subsequent addition of equal As(V) concentration caused Cr(VI) displacement from all materials except pine bark, indicating weak Cr bindings. In view of these results, oak ash and the pyritic material could be used to remove As(V) in concentrations as high as 6 mmol L(-1), even in the presence of a wide range of Cr(VI) concentrations, whereas pine bark could be used to remove Cr(VI) concentrations as high as 6 mmol L(-1). The other materials assayed (including hemp waste, studied for the first time as As(V) and Cr(VI) bio-sorbent) cannot be considered appropriate to remove As(V) and/or Cr(VI) from polluted media.

  19. Derfor elsker og hader vi positiv psykologi

    DEFF Research Database (Denmark)

    Mehlsen, Camilla

    2010-01-01

    Hvorfor er positiv psykologi så populært? Er positiv psykologi ved at blive en religion? Asterisk har mødt tre fremtrædende forskere, der forklarer, hvorfor vi elsker og hader positiv psykolog.......Hvorfor er positiv psykologi så populært? Er positiv psykologi ved at blive en religion? Asterisk har mødt tre fremtrædende forskere, der forklarer, hvorfor vi elsker og hader positiv psykolog....

  20. SaVi: satellite constellation visualization

    CERN Document Server

    Wood, Lloyd

    2012-01-01

    SaVi, a program for visualizing satellite orbits, movement, and coverage, is maintained at the University of Surrey. This tool has been used for research in academic papers, and by industry companies designing and intending to deploy satellite constellations. It has also proven useful for demonstrating aspects of satellite constellations and their geometry, coverage and movement for educational and teaching purposes. SaVi is introduced and described briefly here.

  1. Remoción de Cromo (VI por una Cepa de Paecilomyces sp Resistente a Cromato Removal of Chromium (VI in a Chromate-Resistant Strain of Paecilomyces sp

    Directory of Open Access Journals (Sweden)

    Juan F Cárdenas-González

    2011-01-01

    Full Text Available Se analizó la capacidad de remoción de Cr(VI de una cepa de Paecilomyces sp. Cuando el hongo se incubó en medio mínimo con glucosa y otras fuentes de carbono comerciales y de bajo costo, como azúcar moscabada y piloncillo ó glicerol, en presencia de 50 mg/L de Cr(VI, removió totalmente el Cr(VI. La reducción a Cr(III ocurre en el medio de cultivo después de 7 días de incubación a 28°C, pH 4.0, y un inoculo de 38 mg. El hongo también redujo eficientemente la concentración de Cr(VI a partir de tierra contaminada. Los resultados indican que la cepa de Paecilomyces sp tiene la capacidad de reducir Cr(VI a Cr(III, y por lo tanto puede utilizarse para eliminar la contaminación por Cr(VI.The ability to reduce chromium (VI by a fungal strain of Paecilomyces sp was studied. When it was incubated in minimal medium with glucose and other inexpensive commercial carbon sources such as unrefined and brown sugar or glycerol, in the presence of 50 mg/L of Cr(VI, the strain caused complete removal of Cr(VI. The reduction to Cr (III occurs in the growth medium after 7 days of incubation, at 28°C, pH 4.0, and inoculum of 38 mg. Also, the fungi efficiently reduced the concentration of Cr(VI from contaminated soil wastes. The results indicate that the fungal strain of Paecilomyces sp has the capacity of reducing Cr(VI to Cr(III, and therefore it could be useful for the removal of Cr(VI pollution.

  2. Ex-situ bioremediation of U(VI from contaminated mine water using Acidithiobacillus ferrooxidans strains

    Directory of Open Access Journals (Sweden)

    Maria eRomero-Gonzalez

    2016-05-01

    Full Text Available The ex-situ bioremoval of U(VI from contaminated water using Acidithiobacillus ferrooxidans strain 8455 and 13538 was studied under a range of pH and uranium concentrations. The effect of pH on the growth of bacteria was evaluated across the range 1.5 – 4.5 pH units. The respiration rate of At. ferrooxidans at different U(VI concentrations was quantified as a measure of the rate of metabolic activity over time using an oxygen electrode. The biosorption process was quantified using a uranyl nitrate solution, U-spiked growth media and U-contaminated mine water. The results showed that both strains of At. ferrooxidans are able to remove U(VI from solution at pH 2.5 – 4.5, exhibiting a buffering capacity at pH 3.5. The respiration rate of the micro-organism was affected at U(VI concentration of 30 mg L-1. The kinetics of the sorption fitted a pseudo-first order equation, and depended on the concentration of U(VI. The KD obtained from the biosorption experiments indicated that strain 8455 is more efficient for the removal of U(VI. A bioreactor designed to treat a solution of 100 mg U(VI L-1 removed at least 50% of the U(VI in water. The study demonstrated that At. ferrooxidans can be used for the ex-situ bioremediation of U(VI contaminated mine water.

  3. Adsorption Properties of Bentonite with In Situ Immobilized Polyaniline Towards Anionic Forms of Cr(VI, Mo(VI, W(VI, V(V

    Directory of Open Access Journals (Sweden)

    Kateryna RYABCHENKO

    2016-05-01

    Full Text Available A new composite material bentonite-PANI was synthesized by in situ immobilization of polyaniline (PANI on the surface of natural mineral bentonite. It was established as a result of the modification of bentonite a surface area and an interlayer distance of mineral decrease and particles of bentonite transformed of irregular shape with different porosity on irregularly shaped particles of smaller size. It has been found that the total Cr(VI ions extraction took place under the acid conditions (pH=1 – 2 and W(VI ions have been well adsorbed in the pH range from 1 to 8 by the composite bentonite-PANI unlike the initial mineral. Whereas adsorption of oxo anions of V(V and Mo(VI made up some 50%. It is proved that the in situ immobilization of bentonite by polyaniline leads to increasing the value of adsorption capacity towards the investigated ions compared with the initial mineral. It was established that the adsorption properties of the synthesized composite with respect to the studied oxo ions were worse than the adsorption properties of composite vermiculite-PANI, similar to the composite Sokyryntsyy clinoptilolite-PANI and better than composites of polyaniline with Podilskyy saponite and Karelian shungite.DOI: http://dx.doi.org/10.5755/j01.ms.22.2.6976

  4. Actinide(IV) and actinide(VI) carbonate speciation studies by PAS and NMR spectroscopies; Yucca Mountain Project: Milestone report 3031-WBS 1.2.3.4.1.3.1

    Energy Technology Data Exchange (ETDEWEB)

    Clark, D.L.; Ekberg, S.A.; Morris, D.E.; Palmer, P.D.; Tait, C.D.

    1994-09-01

    Pulsed-laser photoacoustic spectroscopy (PAS) and Fourier-transform nuclear magnetic resonance (NMR) spectroscopy were used to study speciation of actinide(IV) and actinide(VI) ions (Np, Pu, Am) in aqueous carbonate solutions vs pH, carbonate content, actinide content, temperature. PAS focused on Pu(IV) speciation. Stability fields on a pH (8.4 to 12.0) versus total carbonate content (0.003 to 1.0 M) plot for dilute Pu(IV) carbonate species ([Pu]{sub tot} = 1 mM) were mapped. Four plutonium species, with absorption peaks at 486, 492, 500, and 512 nm were found. Loss of a single carbonate ligand does not account for the difference in speciation for the 486 and 492 nm absorption peaks, nor can any of the observed species be identified as colloidal Pu(IV). NMR data have been obtained for UO{sub 2}{sup 2+}, PuO{sub 2}{sup 2+} and AmO{sub 2}{sup 2+}. This report focuses on results for PuO{sub 2}{sup 2+}. The ligand exchange reaction between free and coordinated carbonate on the PuO{sub 2}(CO{sub 3}){sub 3}{sup 4{minus}} systems has been examined by variable temperature {sup 13}C NMR spectroscopy. In each of the six different PuO{sub 2}(CO{sub 3}){sub 3}{sup 4{minus}} samples, two NMR signals are present, one for the free carbonate ligand and one for the carbonate ligand coordinated to a paramagnetic plutonium metal center. The single{sup 13}C resonance line for coordinated carbonate is consistent with expectations of a monomeric PuO{sub 2}(CO{sub 3}){sub 3}{sup 4{minus}} species in solution. A modified Carr-Purcell-Meiboom-Gill NMR pulse sequence was used for determining ligand exchange parameters for paramagnetic actinide complexes. Eyring analysis at standard conditions provided activation parameters of {Delta}H = 38 KJ/M and {Delta}S = {minus}60 J/K for the plutonyl triscarbonate system, suggesting an associative transition state for the plutonyl(VI) carbonate complex self-exchange reaction.

  5. A novel polymer inclusion membrane applied in chromium (VI) separation from aqueous solutions.

    Science.gov (United States)

    Gherasim, Cristina-Veronica; Bourceanu, Gelu; Olariu, Romeo-Iulian; Arsene, Cecilia

    2011-12-15

    In the present work, we analyze the transport properties of a novel polymer inclusion membrane (PIM) containing a poly-vinyl chloride (PVC) polymer matrix and the organic anion exchanger Aliquat 336 as a specific carrier, without addition of plasticizers. The study was specifically focused on the transport properties of Cr(VI) in conditions simulating industrial wastewaters. We analyzed the impact of several parameters on the Cr(VI) transport process such as: the carrier content of the PIM, the pH, and the phases' composition. We concluded that efficient transport processes occur through a PIM containing 40% Aliquat 336/60% PVC (w/w). The process is very fast and efficient for solutions of initial Cr(VI) concentration smaller than 10(-3)mol/L, in which nearly all of Cr(VI) is removed within 3h. The performed experiments prove that Cr(VI) transport through the membrane is a facilitated counter-transport process. The obtained results sustain that this novel non-plasticized membrane possesses enhanced transport properties towards other liquid membranes and plasticized PIMs previously reported as used for Cr(VI) transport. Additionally, it possesses an excellent reliability and a high selectivity for Cr(VI) from mixtures with other metal ions and anions existing in the real industrial effluents. The PIM characterization highlights the plasticizing role of the carrier Aliquat 336.

  6. Myosin VI contributes to synaptic transmission and development at the Drosophila neuromuscular junction

    Directory of Open Access Journals (Sweden)

    Campbell Shelagh

    2011-07-01

    Full Text Available Abstract Background Myosin VI, encoded by jaguar (jar in Drosophila melanogaster, is a unique member of the myosin superfamily of actin-based motor proteins. Myosin VI is the only myosin known to move towards the minus or pointed ends of actin filaments. Although Myosin VI has been implicated in numerous cellular processes as both an anchor and a transporter, little is known about the role of Myosin VI in the nervous system. We previously recovered jar in a screen for genes that modify neuromuscular junction (NMJ development and here we report on the genetic analysis of Myosin VI in synaptic development and function using loss of function jar alleles. Results Our experiments on Drosophila third instar larvae revealed decreased locomotor activity, a decrease in NMJ length, a reduction in synaptic bouton number, and altered synaptic vesicle localization in jar mutants. Furthermore, our studies of synaptic transmission revealed alterations in both basal synaptic transmission and short-term plasticity at the jar mutant neuromuscular synapse. Conclusions Altogether these findings indicate that Myosin VI is important for proper synaptic function and morphology. Myosin VI may be functioning as an anchor to tether vesicles to the bouton periphery and, thereby, participating in the regulation of synaptic vesicle mobilization during synaptic transmission.

  7. Simultaneously photocatalytic treatment of hexavalent chromium (Cr(VI)) and endocrine disrupting compounds (EDCs) using rotating reactor under solar irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Youngji [Korea Institute of Energy Research, New and Renewable Energy Research Division, Hydrogen Laboratory, 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Yonsei University, Department of Chemical and Biomolecular Engineering, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Joo, Hyunku [Korea Institute of Energy Research, New and Renewable Energy Research Division, Hydrogen Laboratory, 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Her, Namguk [Korea Army Academy at Young-Cheon, Department of Chemistry and Environmental Science, 135-1 Changhari, Kokyungmeon, Young-cheon, Gyeongbuk 770-849 (Korea, Republic of); Yoon, Yeomin [University of South Carolina, Department of Civil and Environmental Engineering, Columbia, SC 29208 (United States); Sohn, Jinsik [Kookmin University, School of Civil and Environmental Engineering, 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702 (Korea, Republic of); Kim, Sungpyo [Korea University, Department of Environmental Engineering, Sejong 339-700 (Korea, Republic of); Yoon, Jaekyung, E-mail: jyoon@kier.re.kr [Korea Institute of Energy Research, New and Renewable Energy Research Division, Hydrogen Laboratory, 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of)

    2015-05-15

    Highlights: • Self-rotating reactor including TiO{sub 2} NTs is applied under solar irradiation. • Simultaneously photocatalysis of Cr(VI) and EDCs is observed to be up to 95%. • Photocatalytic reactions of Cr(VI) and EDCs are favorable under acidic pH. • Charge interaction and hole scavenge between TiO{sub 2} and pollutants are synergy factors. - Abstract: In this study, simultaneous treatments, reduction of hexavalent chromium (Cr(VI)) and oxidation of endocrine disrupting compounds (EDCs), such as bisphenol A (BPA), 17α-ethinyl estradiol (EE2) and 17β-estradiol (E2), were investigated with a rotating photocatalytic reactor including TiO{sub 2} nanotubes formed on titanium mesh substrates under solar UV irradiation. In the laboratory tests with a rotating type I reactor, synergy effects of the simultaneous photocatalytic reduction and oxidation of inorganic (Cr(VI)) and organic (BPA) pollutants were achieved. Particularly, the concurrent photocatalytic reduction of Cr(VI) and oxidation of BPA was higher under acidic conditions. The enhanced reaction efficiency of both pollutants was attributed to a stronger charge interaction between TiO{sub 2} nanotubes (positive charge) and the anionic form of Cr(VI) (negative charge), which are prevented recombination (electron–hole pair) by the hole scavenging effect of BPA. In the extended outdoor tests with a rotating type II reactor under solar irradiation, the experiment was extended to examine the simultaneous reduction of Cr(VI) in the presence of additional EDCs, such as EE2 and E2 as well as BPA. The findings showed that synergic effect of both photocatalytic reduction and oxidation was confirmed with single-component (Cr(VI) only), two-components (Cr(VI)/BPA, Cr(VI)/EE2, and Cr(VI)/E2), and four-components (Cr(VI)/BPA/EE2/E2) under various solar irradiation conditions.

  8. Chromium(VI) Bioremoval by Pseudomonas Bacteria: Role of Microbial Exudates for Natural Attenuation and Biotreatment of Cr(VI) Contamination

    Energy Technology Data Exchange (ETDEWEB)

    N Mercan Dogan; C Kantar; S Gulcan; C Dodge; B Coskun Yilmaz; M Ali Mazmanci

    2011-12-31

    Laboratory batch and column experiments were conducted to investigate the role of microbial exudates, e.g., exopolymeric substance (EPS) and alginic acid, on microbial Cr(VI) reduction by two different Pseudomonas strains (P. putida P18 and P. aeuroginosa P16) as a method for treating subsurface environment contaminated with Cr(VI). Our results indicate that microbial exudates significantly enhanced microbial Cr(VI) reduction rates by forming less toxic and highly soluble organo-Cr(III) complexes despite the fact Cr(III) has a very low solubility under the experimental conditions studied (e.g., pH 7). The formation of soluble organo-Cr(III) complexes led to the protection of the cells and chromate reductases from inactivation. In systems with no organic ligands, soluble organo-Cr(III) end products were formed between Cr(III) and the EPS directly released by bacteria due to cell lysis. Our results also provide evidence that cell lysis played an important role in microbial Cr(VI) reduction by Pseudomonas bacteria due to the release of constitutive reductases that intracellularly and/or extracellularly catalyzed the reduction of Cr(VI) to Cr(III). The overall results highlight the need for incorporation of the release and formation of organo-Cr(III) complexes into reactive transport models to more accurately design and monitor in situ microbial remediation techniques for the treatment of subsurface systems contaminated with Cr(VI).

  9. Chromium(VI) bioremoval by pseudomonas bacteria: role of microbial exudates for natural attenuation and biotreatment of Cr(VI) contamination

    Energy Technology Data Exchange (ETDEWEB)

    Dogan, N.M.; Dodge, C.; Kantar, C.; Gulcan, S.; Yilmaz, B.C.; Mazmanci, M.A.

    2011-02-14

    Laboratory batch and column experiments were conducted to investigate the role of microbial exudates, e.g., exopolymeric substance (EPS) and alginic acid, on microbial Cr(VI) reduction by two different Pseudomonas strains (P. putida P18 and P. aeuroginosa P16) as a method for treating subsurface environment contaminated with Cr(VI). Our results indicate that microbial exudates significantly enhanced microbial Cr(VI) reduction rates by forming less toxic and highly soluble organo-Cr(III) complexes despite the fact Cr(III) has a very low solubility under the experimental conditions studied (e.g., pH 7). The formation of soluble organo-Cr(III) complexes led to the protection of the cells and chromate reductases from inactivation. In systems with no organic ligands, soluble organo-Cr(III) end products were formed between Cr(III) and the EPS directly released by bacteria due to cell lysis. Our results also provide evidence that cell lysis played an important role in microbial Cr(VI) reduction by Pseudomonas bacteria due to the release of constitutive reductases that intracellularly and/or extracellularly catalyzed the reduction of Cr(VI) to Cr(III). The overall results highlight the need for incorporation of the release and formation of organo-Cr(III) complexes into reactive transport models to more accurately design and monitor in situ microbial remediation techniques for the treatment of subsurface systems contaminated with Cr(VI).

  10. Reduction of Health Risks Due to Chromium(VI)Using Mesquite: A Potential Cr Phytoremediator

    Energy Technology Data Exchange (ETDEWEB)

    Gardea-Torresdey, Jorge L.; Aldrich, Mary V.; Peralta-Videa, Jose R.; Parsons, Jason G.

    2004-03-29

    Chromium is a transition metal extensively used in industry. Cr mining and industrial operations account for chromium wastes at Superfund sites in the United States. A study was performed to investigate the possibility of using mesquite (Prosopis spp.), which is an indigenous desert plant species, to remove Cr from contaminated sites. In this study, mesquite plants were grown in an agar-based medium containing 75 mg L-1 and 125 mg L-1 of Cr(VI). The Cr content of leaf tissue (992 mg kg-1 of dry weight, from 125 mg L-1 of Cr(VI)) indicated that mesquite could be classified as a chromium hyperaccumulator. X-ray absorption spectroscopy (XAS) studies performed to experimental samples showed that mesquite roots absorbed some of the supplied Cr(VI). However, the data analyses of plant tissues demonstrated that the absorbed Cr(VI) was fully reduced to Cr(III) in the leaf tissue.

  11. Long-term diffusion of U(VI) in bentonite: Dependence on density.

    Science.gov (United States)

    Joseph, Claudia; Mibus, Jens; Trepte, Paul; Müller, Christa; Brendler, Vinzenz; Park, Dan M; Jiao, Yongqin; Kersting, Annie B; Zavarin, Mavrik

    2017-01-01

    As a contribution to the safety assessment of nuclear waste repositories, U(VI) diffusion through the potential buffer material MX-80 bentonite was investigated at three clay dry densities over six years. Synthetic MX-80 model pore water was used as background electrolyte. Speciation calculations showed that Ca2UO2(CO3)3(aq) was the main U(VI) species. The in- and out-diffusion of U(VI) was investigated separately. U(VI) diffused about 3mm, 1.5mm, and 1mm into the clay plug at ρ=1.3, 1.6, and 1.9g/cm(3), respectively. No through-diffusion of the U(VI) tracer was observed. However, leaching of natural uranium contained in the clay occurred and uranium was detected in all receiving reservoirs. As expected, the effective and apparent diffusion coefficients, De and Da, decreased with increasing dry density. The Da values for the out-diffusion of natural U(VI) were in good agreement with previously determined values. Surprisingly, Da values for the in-diffusion of U(VI) were about two orders of magnitude lower than values obtained in short-term in-diffusion experiments reported in the literature. Some potential reasons for this behavior that were evaluated are changes of the U(VI) speciation within the clay (precipitation, reduction) or changes of the clay porosity and pore connectivity with time. By applying Archie's law and the extended Archie's law, it was estimated that a significantly smaller effective porosity must be present for the long-term in-diffusion of U(VI). The results suggest that long-term studies of key transport phenomena may reveal additional processes that can directly impact long-term repository safety assessments.

  12. Mechanical investigation of U(VI) on pyrrhotite by batch, EXAFS and modeling techniques.

    Science.gov (United States)

    Liu, Haibo; Zhu, Yuke; Xu, Bin; Li, Ping; Sun, Yubing; Chen, Tianhu

    2017-01-15

    The interaction mechanism of U(VI) on pyrrhotite was demonstrated by batch, spectroscopic and modeling techniques. Pyrite was selected as control group in this study. The removal of U(VI) on pyrite and pyrrhotite significantly decreased with increasing ionic strength from 0.001 to 0.1mol/L at pH 2.0-6.0, whereas the no effect of ionic strength was observed at pH >6.0. The maximum removal capacity of U(VI) on pyrite and pyrrhotite calculated from Langmuir model was 10.20 and 21.34mgg(-1) at pH 4.0 and 333K, respectively. The XPS analysis indicated the U(VI) was primarily adsorbed on pyrrhotite and pyrite and then approximately 15.5 and 9.8% of U(VI) were reduced to U(IV) by pyrrhotite and pyrite after 20 days, respectively. Based on the XANES analysis, the adsorption edge of uranium-containing pyrrhotite located between U(IV)O2(s) and U(VI)O2(2+) spectra. The EXAFS analysis demonstrated the inner-sphere surface complexation of U(VI) on pyrrhotite due to the occurrence of U-S shell, whereas the U-U shell revealed the reductive co-precipitates of U(VI) on pyrrhotite/pyrite with increasing reaction times. The surface complexation modeling showed that outer- and inner-surface complexation dominated the U(VI) removal at pH5.0, respectively. The findings presented herein play a crucial role in the removal of radionuclides on iron sulfide in environmental cleanup applications.

  13. The role of intracellular zinc in chromium(VI)-induced oxidative stress, DNA damage and apoptosis.

    Science.gov (United States)

    Rudolf, Emil; Cervinka, Miroslav

    2006-09-25

    Several studies have demonstrated that zinc is required for the optimal functioning of the skin. Changes in intracellular zinc concentrations have been associated with both improved protection of skin cells against various noxious factors as well as with increased susceptibility to external stress. Still, little is known about the role of intracellular zinc in hexavalent chromium (Cr(VI))-induced skin injury. To address this question, the effects of zinc deficiency or supplementation on Cr(VI)-induced cytotoxicity, oxidative stress, DNA injury and cell death were investigated in human diploid dermal fibroblasts during 48 h. Zinc levels in fibroblasts were manipulated by pretreatment of cells with 100 microM ZnSO4 and 4 or 25 microM zinc chelator TPEN. Cr(VI) (50, 10 and 1 microM) was found to produce time- and dose-dependent cytotoxicity resulting in oxidative stress, suppression of antioxidant systems and activation of p53-dependent apoptosis which is reported for the first time in this model in relation to environmental Cr(VI). Increased intracellular zinc partially attenuated Cr(VI)-induced cytotoxicity, oxidative stress and apoptosis by enhancing cellular antioxidant systems while inhibiting Cr(VI)-dependent apoptosis by preventing the activation of caspase-3. Decreased intracellular zinc enhanced cytotoxic effects of all the tested Cr(VI) concentrations, leading to rapid loss of cell membrane integrity and nuclear dispersion--hallmarks of necrosis. These new findings suggest that Cr(VI) as a model environmental toxin may damage in deeper regions residing skin fibroblasts whose susceptibility to such toxin depends among others on their intracellular Zn levels. Further investigation of the impact of Zn status on skin cells as well as any other cell populations exposed to Cr(VI) or other heavy metals is warranted.

  14. Serviceability of unpaved roads: a case study applied to net road from Viçosa, Minas Gerais - doi: 10.4025/actascitechnol.v33i2.10328

    Directory of Open Access Journals (Sweden)

    Taciano Oliveira da Silva

    2011-04-01

    Full Text Available This paper addresses the adaptation of the method of classification of unpaved roads developed by Eaton to the field conditions of local roads from the city of Viçosa, Minas Gerais State, Brazil, considering its potential as a support tool for the management of these roads. This study was developed encompassing objective evaluation, carried out with the application of a note scale, and subjective evaluation, according to the methodology of Eaton, which were performed by a team that accomplished the field inspections, attributing notes to the 20 sample units, each one 50 meters long and representing 10 analyzed unpaved road segments. Conclusions are as follows: (i it was not observed any correlation between data from the objective and the subjective field evaluations, leading to the conclusion that the use of the Eaton and others methodologies can be misleading to the management of the maintenance of unpaved not reflecting their real priorities; (ii there is correlation between the subjective evaluation of the road sections and the subjective evaluation of all sample units, indicating to be consistent the application of this procedure.

  15. Study of the temperature influence during the uranium (Vi) sorption on surface of ZrP{sub 2}O{sub 7} in presence of oxalic and salicylic acid; Estudio de la influencia de la temperatura durante la sorcion de uranio (VI) en la superficie del ZrP{sub 2}O{sub 7} en presencia de acidos oxalico y salicilico

    Energy Technology Data Exchange (ETDEWEB)

    Garcia G, N.

    2013-07-01

    This work studies the effect of temperature on the uranium (Vi) sorption onto zirconium diphosphate in the presence of organic acids (oxalic and salicylic acids). Zirconium diphosphate was synthesized by a chemical condensation reaction and characterized using several analytical techniques, in order to check its purity. This point is very important because the presence of any impurities or secondary phases may interfere with the hydration and sorption process. Prior to the sorption experiments, three batches of zirconium diphosphate were pre-equilibrated with NaClO{sub 4}, oxalic acid or salicylic acid solutions. The hydrated solids were washed and dried and then again characterized in order to study the interactions between organic acids and zirconium diphosphate surface. Uranium sorption onto zirconium diphosphate (pre-equilibrated with NaClO{sub 4}, oxalic acid and salicylic acid solutions) was investigated as a function of ph, organic acid and temperature (20, 40 y 60 grades C). Thermodynamic parameters for the sorption reactions (enthalpy change, entropy change and Gibbs free energy change) were determined from temperature dependence of distribution coefficient by using the Vant Hoff equation. Solids characterization after hydration shows that exist an interaction between organic acids and ZrP{sub 2}O{sub 7}. This fact was confirmed with the microcalorimetry study, the reaction heat for hydration of zirconium diphosphate in NaClO{sub 4} solution was exothermic (-269.59 mJ) and for hydration of zirconium diphosphate in oxalic acid solution was endothermic (53.64 mJ). The experimental results showed important differences in the sorption mechanisms for the reaction of Uranium with ZrP{sub 2}O{sub 7} in the presence and absence of organic acids. For the zirconium diphosphate hydrated with oxalic acid, the sorption percentage was 50% from lowest ph values. For the zirconium diphosphate hydrated with salicylic acid, the initial concentration of uranium was 6 x 10

  16. Structural and Electronic Properties of IV-VI Semiconductor Nanodots

    Science.gov (United States)

    Leitsmann, Roman; Bechstedt, Friedhelm

    2008-03-01

    The characterization of nanostructure properties versus dimension and surface passivation is of increasing importance for the nanotechnology. Especially the stoichiometry, geometry, and the electronic states of IV-VI semiconductor nanodots are of special interest [1,2]. We use ab initio methods to calculate structural and electronic properties of colloidal IV-VI semiconductor nanodots as a function of the dot diameter. A method to passivate the non-directional dangling bonds at the nanodot surfaces is derived and used to study the confinement effect on the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) states. In addition we take the influence of relativistic (spin-orbit coupling -- SOC ) and excitonic effects into account. While the SOC leads to a considerable decrease of the HOMO-LUMO gap, excitonic effects play a minor role. [1] JACS 128, 10337 (2006) [2] JACS 129, 11354 (2007)

  17. Upscaling of U(VI) Desorption and Transport Using Decimeter-Scale Tanks

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Derrick

    2015-01-28

    Experimental work was used to validate modeling studies and develop multicontinuum models of U(VI) transport in a contaminated aquifer. At the bench scale, it has been shown that U(VI) desorption is rate-limited and that rates are dependent on the bicarbonate concentration. Two decimeter-scale experiments were conducted in order to help establish rigorous upscaling approaches that could be tested at the tracer test and plume scales.

  18. Upscaling of U(VI) Desorption and Transport Using Decimeter-Scale Tanks

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Derrick [Colorado School of Mines, Golden, CO (United States)

    2014-12-22

    Experimental work was used to validate modeling studies and develop multicontinuum models of U(VI) transport in a contaminated aquifer. At the bench scale, it has been shown that U(VI) desorption is rate-limited and that rates are dependent on the bicarbonate concentration. Two decimeter-scale experiments were conducted in order to help establish rigorous upscaling approaches that could be tested at the tracer test and plume scales.

  19. Differential Isotopic Fractionation during Cr(VI) Reduction by an Aquifer-Derived Bacterium under Aerobic versus Denitrifying Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Han, R.; Qin, L.; Brown, S. T.; Christensen, J. N.; Beller, H. R.

    2012-01-27

    We studied Cr isotopic fractionation during Cr(VI) reduction by Pseudomonas stutzeri strain RCH2. Finally, despite the fact that strain RCH2 reduces Cr(VI) cometabolically under both aerobic and denitrifying conditions and at similar specific rates, fractionation was markedly different under these two conditions (ε was ~2‰ aerobically and ~0.4‰ under denitrifying conditions).

  20. Why College Students Want to Learn Asian Languages: A Comparative Study of Motivational Factors for the Selection of Chinese, Japanese, Korean and Vi-etnamese

    Directory of Open Access Journals (Sweden)

    Jack Jinghui Liu

    2008-01-01

    Full Text Available In recent years, more higher educational institutions started to offer less commonly taught languages, and the enrollments in Asian languages have been increasing. However, little was known about why students are interested in the study of a certain Asian lan-guage. This study investigates students’ motivation in the selection of one of four Asian languages: Chinese, Japanese, Korean and Viet-namese, and compares the motivational factors across these lan-guages. Ninety-nine college students who enrolled in the first semes-ter of one of these Asian language classes responded to a Likert-scale questionnaire and open-ended questions. The findings showed that a wide variety of reasons initially motivated college students to learn an Asian language. These fell into six major motivational fac-tors: cultural understanding, heritage-related factor, instrumental ori-entation, integrative orientation, achievement orientation, and admin-istrative. The study found that there were both similarities and differences in the motivational factors across the four Asian lan-guages. The cultural understanding and integrative orientation were the top two shared motivational factors, and administrative orienta-tion was a weak factor across all language groups. In addition, differ-ences in rank order among the six motivational factors were found between East Asian and Southeast Asian languages.

  1. Derivative spectrophotometric determination of uranium (VI using diacetyl monoxime isonicotinoyl hydrazone (DMIH

    Directory of Open Access Journals (Sweden)

    ChandraSekhar Reddy Gadikota

    2011-08-01

    Full Text Available Uranium (VI forms a yellow coloured water soluble complex with diacetyl monoxime isonicotinoyl hydrazone (DMIH reagent in acidic buffer of pH 3.25 with ?max at 364 nm. The molar absorptivity and sandell’s sensitivity are 1.63 X 10 4 L.mol -1.cm-1 and 0.00307692 µg/cm 2, respectively. The Beer’s law validity range is 1.19–14.28 µg/mL. Uranium (VI forms (M:L 1:1 complex with DMIH and stability constant of the complex is 4.928 X 106 .The derivative spectrophotometric determination of U (VI was carried out by measuring peak height method. The developed derivative spectrophotometric method was employed for the determination of uranium (VI in rock and synthetic samples. The effect of various diverse ions was also studied.

  2. Biosorption of Cr(VI from Aqueous Solution Using Murraya koenigii (Curry tree Stems

    Directory of Open Access Journals (Sweden)

    Selvaraj Suresh

    2016-12-01

    Full Text Available In the present work, the sorption capacity of Murraya Koenigii Stems (MKST, an agricultural waste, is identified for the removal of Cr(VI from aqueous solution and the effect of different process parameters likes pH and adsorbent dosage were studied. pH 1 is observed to be the optimum pH for Cr(VI sorption onto the biosorbent. The equilibrium data of Cr(VI sorption fit well with the Langmuir model with a monolayer sorption capacity of 12.25 mg/g. The results show that the metal ion interacts strongly with the biosorbent and can be effectively used in the removal of Cr(VI from aqueous solution. DOI: http://dx.doi.org/10.17807/orbital.v0i0.867

  3. Removal of Cr(VI from Aqueous Environments Using Micelle-Clay Adsorption

    Directory of Open Access Journals (Sweden)

    Mohannad Qurie

    2013-01-01

    Full Text Available Removal of Cr(VI from aqueous solutions under different conditions was investigated using either clay (montmorillonite or micelle-clay complex, the last obtained by adsorbing critical micelle concentration of octadecyltrimethylammonium ions onto montmorillonite. Batch experiments showed the effects of contact time, adsorbent dosage, and pH on the removal efficiency of Cr(VI from aqueous solutions. Langmuir adsorption isotherm fitted the experimental data giving significant results. Filtration experiments using columns filled with micelle-clay complex mixed with sand were performed to assess Cr(VI removal efficiency under continuous flow at different pH values. The micelle-clay complex used in this study was capable of removing Cr(VI from aqueous solutions without any prior acidification of the sample. Results demonstrated that the removal effectiveness reached nearly 100% when using optimal conditions for both batch and continuous flow techniques.

  4. Removal of aqueous chromate [Cr(VI)] through photocatalysis by using TiO2-coated silica granules.

    Science.gov (United States)

    Saeki, Kazutoshi; Kadono, Mayumi; Nabeshima, Akiko

    2010-01-01

    The aim of this study was to determine the optimal conditions for the treatment of chromate [Cr(VI)]- contaminated water by UV photocatalysis using synthesized TiO(2)-coated silica granules (phi 1.7-4.0 mm) containing 12.4% of TiO(2) in a batch method. The effect of the volume of the solution on Cr(VI) removal was investigated in the photocatalysis process by using 10 g of TiO(2)-coated silica granules in water samples with a constant initial Cr(VI) concentration of 5 mg L(-1). In a 10-mL solution, Cr(VI) concentrations were observed to decrease below the detection limit (photocatalysis process to remove Cr(VI) using 10 g of TiO(2)-coated granules did not fluctuate with the solution volume for samples with a constant initial Cr(VI) concentration. The lower the initial pH of the solution, the greater was the amount of Cr(VI) removed from the solution. The addition of chloride ions to the solutions accelerated the removal of Cr(VI) by UV photocatalysis. Ten grams of TiO(2)-coated silica granules were repeatedly used to the 300-min treatment of the Cr(VI) solution (10 mL, 6 mg L(-1)) till seven cycles. After four cycles of UV photocatalysis, Cr(VI) was completely removed from all the solutions. After the fifth cycle, the Cr(VI) removal capacity of the UV photocatalysis process decreased with the repeated use of the catalyst.

  5. The Spy VI child: a newly discovered Neandertal infant.

    Science.gov (United States)

    Crevecoeur, Isabelle; Bayle, Priscilla; Rougier, Hélène; Maureille, Bruno; Higham, Thomas; van der Plicht, Johannes; De Clerck, Nora; Semal, Patrick

    2010-12-01

    Spy cave (Jemeppe-sur-Sambre, Belgium) is reputed for the two adult Neandertal individuals discovered in situ in 1886. Recent reassessment of the Spy collections has allowed direct radiocarbon dating of these individuals. The sorting of all of the faunal collections has also led to the discovery of the remains of a Neandertal child, Spy VI. This individual is represented by two mandibular corpus fragments. The left fragment is the most complete and both sides preserve the mental foramen. Four deciduous teeth are associated with these mandibular remains: three incisors and one canine. The lower left canine (Spy 645a) conjoins with the corresponding alveolar socket in the left part of the mandible. Following extant standards, the developmental stage of the preserved teeth indicate an age at death of about one and a half years. In addition to performing a classical morphometric comparative study of the mandible and teeth, we have evaluated the dental tissue proportions using high-resolution microtomographic techniques. Our results show that Spy VI generally falls within the Neandertal range of variation. However, this specimen also exhibits particular traits, notably in the dental internal structural organization, which reveals that variation in the immature Neandertal variation is larger than what was variation currently represented by the available fossil record. These observations demonstrate the need for investigating the frequency and expression of immature Neandertal traits in fossil anterior teeth, as well as their temporal and geographic variation. Direct radiocarbon dating of the Spy VI specimen has been conducted in two different laboratories. The results of Spy VI confirm the age previously determined for the two adults, making the Spy Neandertal remains the youngest ever directly dated in northwest Europe.

  6. Thermal detoxification and bloating of chromium(VI) with bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Y.-L., E-mail: yulin@thu.edu.t [Department of Environmental Science and Engineering, Tunghai University, Taichung 40704, Taiwan (China); Hsieh, H.-F.; Peng, Y.-S.; Yang, J.-C. [Department of Environmental Science and Engineering, Tunghai University, Taichung 40704, Taiwan (China); Paul Wang, H. [Department of Environmental Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Sustainable Environmental Research Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Lin, C.-Y.; Shih, W.-L.; Hsu, C.-C. [Department of Environmental Science and Engineering, Tunghai University, Taichung 40704, Taiwan (China)

    2010-07-21

    This study stabilizes and bloats Cr(VI)-sorbed bentonite by heating at high temperature. Cr leaching decreases with increasing temperatures. Heating the sample at 1100 {sup o}C results in a non-detectable Cr concentration in the leachate, equivalent to a Cr leaching percent less than 0.001% (i.e., Cr TCLP concentration <0.018 mg of Cr L{sup -1} of leachate). Morphology observed with a scanning electron microscopy indicates the occurrence of sintering of the sample heated at 1100 {sup o}C. The heated samples also show the occurrence of a vesicant process at 1100 {sup o}C. X-ray absorption spectroscopy results indicate that heating at 500 {sup o}C for 4 h can convert approximately 87% Cr(VI) into Cr(III) that is negligibly toxic; Cr{sub 2}O{sub 3} was detected to be the most abundant Cr species. After heating at higher temperatures, namely 900-1100 {sup o}C, almost all doped Cr(VI) is reduced to Cr(III) as inferred from the height of the pre-edge peak of XANES spectra and/or from XANES simulation.

  7. FUSE Observations of O VI Overlying the Scutum Supershell

    CERN Document Server

    Sterling, N C; Richter, P; Fabian, D; Sembach, K R

    2001-01-01

    We present Far Ultraviolet Spectroscopic Explorer observations of the B0 III star HD 177989 ($l = 17.8^{rm \\o}, b = -11.9^{\\rm o}, d$ = 4.9 kpc). This line of sight passes through the high latitude outflow from the Scutum Supershell (GS 018-04+44), a structure that lies at a kinematic distance of ~ 3.5 kpc, and spans ~ 5$^{\\rm o}$ in diameter. The O VI $\\lambda$1031.93 line is compared with STIS observations of Si IV, C IV, and N V to examine the ionizing mechanisms responsible for producing the high ion absorption, as well as to study the processes by which gas is expelled into the halo. The O VI profile spans a similar velocity range as the other highly ionized atoms, from -70 to +80 km/s. Component fits reveal very broad absorption at the kinematic velocity of the Scutum shell, which differs from the narrow Si IV, C IV, and N V components, suggesting that these other species occupy a more confined region. It is possible that the O VI is present in hot gas from the shell interior that is diffusing into the ...

  8. Cr isotope fractionation factors for Cr(VI) reduction by a metabolically diverse group of bacteria

    Science.gov (United States)

    Basu, Anirban; Johnson, Thomas M.; Sanford, Robert A.

    2014-10-01

    Reduction of Cr(VI) is an important process that determines the geochemical behavior, mobility and bioavailability of Cr in both terrestrial and marine environments. Many metabolically diverse microorganisms possess Cr(VI) reduction capacity. Cr(VI) reduction fractionates Cr isotopes and thus 53Cr/52Cr ratios can be used to monitor Cr(VI) reduction and redox conditions. The magnitude of isotopic fractionation (ε) for a variety of microbial reduction mechanisms must be known for accurate interpretation of observed shifts in 53Cr/52Cr ratios. We determined isotopic fractionation factors for Cr(VI) reduction by metal reducers Geobacter sulfurreducens and Shewanella sp. strain NR, a denitrifying soil bacterium Pseudomonas stutzeri DCP-Ps1, and a sulfate reducer Desulfovibrio vulgaris. All bacteria investigated in this study produced significant Cr isotope fractionation. The fractionation (ε) for G. sulfurreducens, Shewanella sp. (NR), P. stutzeri DCP-Ps1, and D. vulgaris were -3.03‰ ± 0.12‰, -2.17‰ ± 0.22‰, -3.14‰ ± 0.13‰, and -3.01‰ ± 0.11‰, respectively. Despite differences in microbial strains in this study, the ε did not vary significantly except for Shewanella sp. (NR). Our results suggest that strong isotopic fractionation is induced during Cr(VI) reduction under electron donor poor (∼300 μM) conditions.

  9. Optimum Conditions for the Removal of Cr(VI using Modified Eucalyptus Bark

    Directory of Open Access Journals (Sweden)

    Fenjie Niu

    2014-10-01

    Full Text Available The aims of this study were response surface modeling and optimization of Cr(VI removal from solution using formaldehyde-modified eucalyptus bark. A high removal rate of Cr(VI was achieved under the conditions of low adsorbent dosing quantity and high initial concentration of Cr(VI. Analysis of variance showed a high multiple coefficient of determination (R2=0.9875, adjusted determination coefficient (R2Adj=0.9714, and the good second order regression equation. The initial concentration of Cr(VI was 40.15 mg/L, adsorbent dosing quantity 3.40 g/L, and initial reaction pH 2.78, and the largest removal rate was 99.998% under the optimum reaction conditions. Langmuir and Freundlich isothermal models described well adsorption of Cr(VI by the modified stringy bark. Adsorption kinetics studies showed that the adsorption was controlled by multiple factors, dominated by chemical adsorption. The adsorption was found to be spontaneous and endothermic, with △G0 0, and △S0 > 0. Adsorption of Cr(VI by formaldehyde-modified stringy bark was partly controlled by REDOX reactions. The adsorbents were characterized by SEM and FTIR.

  10. Vi er blevet gode til at budgettere(!?!)

    DEFF Research Database (Denmark)

    Kreiner, Kristian

    2015-01-01

    På det seneste har rektor haft anledning til at fortælle os, at vi på CBS er blevet gode til at budgettere. Men hvad det vil sige at være god til at budgettere? Og hvad bliver disse nye færdigheder så brugt til?......På det seneste har rektor haft anledning til at fortælle os, at vi på CBS er blevet gode til at budgettere. Men hvad det vil sige at være god til at budgettere? Og hvad bliver disse nye færdigheder så brugt til?...

  11. Bioprospecting of gum kondagogu (Cochlospermum gossypium) for bioremediation of uranium (VI) from aqueous solution and synthetic nuclear power reactor effluents.

    Science.gov (United States)

    Sashidhar, R B; Selvi, S Kalaignana; Vinod, V T P; Kosuri, Tanuja; Raju, D; Karuna, R

    2015-10-01

    An ecofriendly green chemistry method using a natural biopolymer, Gum Kondagogu (GK) for the removal of U (VI) from aqueous, simulated nuclear effluents was studied. The adsorption characteristic of GK towards U (VI) from aqueous solution was studied at varied pH, contact time, adsorbent dose, initial U (VI) concentration and temperature using UV-Visible spectroscopy and ICP-MS. Maximum adsorption was seen at pH 4, 0.1% GK with 60 min contact time at room temperature. The GK- U (VI) composite was characterized by FT-IR, zeta potential, TEM and SEM-EDAX. The Langmuir isotherm was found to be 487 mg of U (VI) g(-1) of GK. The adsorption capacity and (%) of U (VI) was found to be 490 ± 5.4 mg g(-1) and 98.5%. Moreover adsorption of U (VI) by GK was not influenced by other cations present in the simulated effluents. The adsorbed U (VI) was efficiently stripped from composite using 1 M HCl.

  12. Spectroscopic Studies of Solar Corona VI: Trend in Line-width Variation of Coronal Emission Lines with Height Independent of the Structure of Coronal Loops

    Indian Academy of Sciences (India)

    Jagdev Singh; Takashi Sakurai; Kiyoshi Ichimoto; S. Muneer

    2006-06-01

    We have obtained spectroscopic observations in coronal emission lines by choosing two lines simultaneously, one [Fe X] 6374 Å and the other [Fe XI] 7892 Å or [Fe XIII] 10747 Å or [Fe XIV] 5303 Å. We found that in 95 per cent of the coronal loops observed in 6374 Å, the FWHM of the emission line increases with height above the limb irrespective of the size, shape and orientation of the loop and that in case of 5303 Å line decreases with height in about 89 per cent of the coronal loops. The FWHM of 7892 Å and 10747 Å emission lines show intermediate behavior. The increase in the FWHM of 6374 Å line with height is the steepest among these four lines.We have also studied the intensity ratio and ratio of FWHM of these lines with respect to those of 6374 Å as a function height above the limb. We found that the intensity ratio of 7892 Å and 10747 Å lines with respect to 6374 Å line increases with height and that of 5303 Å to 6374 Å decreases with height above the limb. This implies that temperature in coronal loops will appear to increase with height in the intensity ratio plots of 7892 Å and 6374 Å; and 10747 Å and 6374 Å whereas it will appear to decrease with height in intensity ratio of 5303 Å to 6374 Å line versus height plot. These findings are up to a height of about 200 arcsec above the limb. The varying ratios with height indicate that relatively hotter and colder plasma in coronal loops interact with each other. Therefore, the observed increase in FWHM with height above the limb of coronal emission lines associated with plasma at about 1 MK may not be due to increase in non-thermal motions caused by coronal waves but due to interaction with the relatively hotter plasma. These findings also do not support the existing coronal loop models, which predict an increase in temperature of the loop with height above the limb.

  13. Comparative studies on exchange reactions of hexafluoroacetylacetonate in bis(hexafluoroacetylacetonato)(dimethyl sulfoxide)dioxouranium(VI) in nonaqueous solvent and supercritical CO(2).

    Science.gov (United States)

    Kachi, Yoshihiro; Kayaki, Yoshihito; Tsukahara, Takehiko; Ikariya, Takao; Ikeda, Yasuhisa

    2008-01-07

    Exchange reactions of hexafluoroacetylacetonate (hfacac) in UO2(hfacac)2DMSO (DMSO = dimethyl sulfoxide) in o-C6D4Cl2 and supercritical CO2 (sc-CO2) have been studied using the NMR line-broadening method to compare reactivity in a nonaqueous solvent with that in sc-CO2. It was found that the exchange rates of hfacac in both systems are dependent on the concentration of the enol isomer ([Henol]) of hexafluoroacetylacetone and become slow with an increase in the concentration of free DMSO ([DMSO]). The exchange reaction between free and coordinated DMSO in UO2(hfacac)2DMSO has been also examined in o-C6D4Cl2 and sc-CO2. As a result, the exchange rate of DMSO was found to depend on [DMSO]. From these results, the hfacac exchange reactions in UO2(hfacac)2DMSO in o-C6D4Cl2 and sc-CO2 were proposed to proceed through the mechanism that the ring-opening for one of two coordinated hfacac in UO2(hfacac)2DMSO is the rate-determining step, and the resulting vacant site is coordinated by the incoming Henol, followed by the proton transfer from Henol to hfacac and the ring closure of unidentate hfacac. The rate constants at 60 degrees C and the activation parameters (DeltaH and DeltaS) for the ring-opening path are 35.8 +/- 3.2 s(-1), 57.8 +/- 2.7 kJ.mol(-1), and -42.9 +/- 7.7 J.mol(-1).K(-1) for the o-C6D4Cl2 system, and 518 +/- 50 s(-1), 18.9 +/- 1.8 kJ.mol(-1), and -138 +/- 5 J.mol(-1).K(-1) for the sc-CO2 system, respectively. Differences in kinetic parameters between sc-CO2 and o-C6D4Cl2 systems were proposed to be attributed to the solute-solvent interactions such as Lewis acid-Lewis base interactions and hydrogen bondings between sc-CO2 and beta-diketones.

  14. Studies of two-terminal and four-terminal polycrystalline thin film tandem solar cells based on II-VI materials

    Science.gov (United States)

    Parikh, Viral Y.

    Multijunction solar cells offer the most promising approach to achieve high conversion efficiency by efficient utilization of the solar spectrum. The work presented in this dissertation focuses on the challenges involved in the fabrication of a two-terminal and a four-terminal tandem device. In case of monolithically series-connected tandem devices, the individual optimization of the top and bottom cells is of crucial importance, as either of them may limit the current of the complete device. A major challenge in the development of these cascade solar cells is also the requirement of a low resistance, optically transparent interconnect junction. To meet these challenges, we have tried to optimize the performance of a single junction CdS/CdTe device by reducing the thickness of CdTe without compromising its efficiency. We have achieved a maximum efficiency of 12.1% for CdTe thickness of 0.9 mum which is similar to a standard 2.3 mum CdTe device in our laboratory. The performance of CdS/CdTe device has also been tested by depositing different transparent back contacts. A device efficiency of 9.1% has been obtained with ZnTe:N/ITO as the best transparent back contact. Bifacial illumination studies (J-V and QE) of these devices have been carried out to understand the current transport mechanism occurring at the hack contact. The requirements of the individual layers of an interconnect junction are reviewed and their optical and electrical properties investigated before fabricating a tandem device. The potential of HgCdTe as an absorber layer for a bottom cell is explored. We are able to achieve the best HgCdTe films with a desired bandgap of 1.1 eV at a substrate deposition temperature of 97°C. These films also have the morphological and electrical properties needed for cell fabrication. Cu-Au proves to be the best ohmic metal back contact to the CdS/HgCdTe device. An all-sputtered two-terminal tandem with CdS/CdTe as top cell and CdS/HgCdTe as bottom cell has been

  15. New low cost sorbents for Cr(VI – batch and column experiments

    Directory of Open Access Journals (Sweden)

    Šillerová H.

    2013-04-01

    Full Text Available The use of agricultural byproducts and industrial biowaste materials has been shown to be an attractive technique for removing Cr(VI from contaminated waste waters. In this study, used brewers draff, peat moss, sawdust, grape stalks and husks were investigated as novel biosorbents for Cr(VI. The material was tested in two different modifications. The material was dried, cut and sieved and part of it was subjected to acid (2 M H2SO4 and alkali (0.5 M NaOH pre-treatments to remove starch, proteins and sugars. Fourier transform infrared rays analysis on solid phase (FTIR-ATR was used to determine the main functional groups that might control the metal uptake. Batch experiments were performed at different pH values (3, 4.5, 6 and at various initial concentration of Cr(VI (25–2012;250 mg L−1. Two equilibrium empirical models, Langmuir and Freundlich, were used to describe Cr(VI adsorption. In order to identify possible reduction processes, ion exchange separation on the AG1-X8 resin was used to separate the anionic Cr(VI and the reduced cationic Cr(III from the aqueous phase after biosorption. As expected, Cr(VI removal was pH-dependent and fitted well both the Langmuir and Freundlich isotherm models. The ion exchange separation showed that Cr(VI reduction had occurred in the solution during biosorption. The efficiency of draff as a biosorbent was comparable (or even higher to highly organic materials (e.g., composted peat showing its potential application for Cr(VI decontamination.

  16. CHROMIUM (VI ADSORPTION ONTO ACTIVATED KRAFT LIGNIN PRODUCED FROM ALFA GRASS (STIPA TENACISSIMA

    Directory of Open Access Journals (Sweden)

    Nassima Tazrouti

    2009-05-01

    Full Text Available Activated lignin having a surface area of 1023 m2 g-1 has been prepared from sulfate lignin that was treated by 30% H2O2 and carbonized at 300 °C in order to test the chromium (VI adsorption from aqueous solution. The influence of contact time, pH, initial concentrations of adsorbent and adsorbate, and temperature on the adsorption capacity were investi-gated. The maximum removal of Cr(VI was found to be 92.36 % at pH=2 and a contact time of 80 min. Optimal concentration of lignin and Cr(VI were found to be 3.8 g L-1 and 180 mg L-1, respectively. The adsorption kinetics data fitted well with a pseudo-second-order equation, and the rate of removal of chromium was found to speed up with increasing temperature. Activation energy for the adsorption process was found to be 18.19 kJ mol-1. The Langmuir and Freundlich adsorption isotherm models were applied to describe the isotherm and isotherm constants for the adsorption of Cr (VI on lignin. These constants and correlation coefficients of the isotherm models were calculated and compared. Results indicated that Cr (VI uptake could be described by the Langmuir adsorption model. The maximum adsorption capacity (qm of Cr (VI on lignin was 75.75 mg g-1 at 40°C. The dimensionless equilibrium parameter (RL signified a favorable adsorption of Cr (VI on lignin and was found to be between 0.0601 and 0.818 (0study indicates that lignin has the potential to become an effective and economical adsorbent for removal Cr (VI from waste water.

  17. Applications of Ferrate(VI) to Wastewater Reclamation and Water Treatment

    Science.gov (United States)

    Kim, H.; Choi, H.; Lee, K.; Nam, J.; Kim, I.

    2010-12-01

    The estimated amount of water resources is about 63 billion cubic meters in Korea. However, due to the lack of precipitation during the dry season, natural flows are not enough for the water supply. In addition, since the lack of water affects water quality, environmental problems are occurred in natural and social systems. In this study, we investigated the application feasibility of ferrate(VI) systems to water and wastewater treatment. And we'd like to suggest an alternative solution for conservation and efficient reuse of the limited water resources. In the research area of environmental applications, a primary interest has been focused to the power of ferrate(VI) systems in the decomposition of pollutants in wastewater and industrial effluents due to its potential use as a strong, relatively non-toxic, and oxidizing agent for diverse environmental contaminants. Also ferrate(VI) has additional advantages as a very efficient coagulant and a sorbent of pollutants. We have analysed and compared several ferrate(VI) manufacturing processes, especially focused on the electro chemical methods(Fig. 1). And we have investigated the applications of the manufactured ferrate(VI) in our own laboratory and the commercial ferrate(VI) to decomposition of persistent organic pollutants in water. Under optimal conditions, the removal efficiencies of 2-chlorophenol and benzothiophene were above 90%(Fig. 2). The ferrate system(VI) is promising and can be one of the most efficient alternatives among the advanced oxidation processes(AOPs) for degradation of persistent organic pollutants, and is an innovative technology for the wastewater reclamation, water reusing systems, and water treatment systems. Fig 1. Comparison of Electro-Chemical Ferrate(VI) manufacturing Processes Fig 2. Degradation of 2-Chlorophenol and Bezothiophene by Ferrate. (Experimental Conditions : 2-CP = 3ppm, BT = 5ppm, NaClO4 = 0.05M)

  18. Localization and mobility of synaptic vesicles in Myosin VI mutants of Drosophila.

    Directory of Open Access Journals (Sweden)

    Marta Kisiel

    Full Text Available BACKGROUND: At the Drosophila neuromuscular junction (NMJ, synaptic vesicles are mobile; however, the mechanisms that regulate vesicle traffic at the nerve terminal are not fully understood. Myosin VI has been shown to be important for proper synaptic physiology and morphology at the NMJ, likely by functioning as a vesicle tether. Here we investigate vesicle dynamics in Myosin VI mutants of Drosophila. RESULTS: In Drosophila, Myosin VI is encoded by the gene, jaguar (jar. To visualize active vesicle cycling we used FM dye loading and compared loss of function alleles of jar with controls. These studies revealed a differential distribution of vesicles at the jar mutant nerve terminal, with the newly endocytosed vesicles observed throughout the mutant boutons in contrast to the peripheral localization visualized at control NMJs. This finding is consistent with a role for Myosin VI in restraining vesicle mobility at the synapse to ensure proper localization. To further investigate regulation of vesicle dynamics by Myosin VI, FRAP analysis was used to analyze movement of GFP-labeled synaptic vesicles within individual boutons. FRAP revealed that synaptic vesicles are moving more freely in the jar mutant boutons, indicated by changes in initial bleach depth and rapid recovery of fluorescence following photobleaching. CONCLUSION: This data provides insights into the role for Myosin VI in mediating synaptic vesicle dynamics at the nerve terminal. We observed mislocalization of actively cycling vesicles and an apparent increase in vesicle mobility when Myosin VI levels are reduced. These observations support the notion that a major function of Myosin VI in the nerve terminal is tethering synaptic vesicles to proper sub-cellular location within the bouton.

  19. Synthesis and application of magnetic hydrogel for Cr(VI) removal from contaminated water

    KAUST Repository

    Tang, Samuel C N

    2010-11-01

    Many magnetic adsorbents reported in the literature, such as iron oxides, for Cr(VI) removal have been found effective only in low pH environments. Moreover, the application of polymeric hydrogels on heavy metal removal has been hindered by difficulties in separation by filtration. In this study, a magnetic cationic hydrogel was synthesized for Cr(VI) removal from contaminated water, making use of the advantages of magnetic adsorbents and polymeric hydrogels. The magnetic hydrogel was produced by imbedding 10-nm γ-Fe2O 3 nanoparticles into the polymeric matrix via radical polymerization. Characterization of the hydrogel was undertaken with Fourier transform infrared and vibrating sample magnetometer; swelling properties were tested and anionic adsorption capacity was evaluated. The magnetic hydrogel showed a superior Cr(VI) removal capacity compared to commercial products such as MIEX®. Cr(VI) removal was independent of solution pH. Results show that Cr(VI) removal kinetics was improved drastically by grinding the bulk hydrogel into powder form. At relevant concentrations, common water anions (e.g., Cl-, SO4 2-, PO4 3-) and natural organic matter did not exhibit significant inhibition of Cr(VI) adsorption onto the hydrogel. Results of vibrating sample magnetometer indicate that the magnetic hydrogel can be easily separated from treatment systems. Regeneration of the magnetic hydrogel can be easily achieved by washing the Cr(VI)-loaded hydrogel with 0.5 M NaCl solution, with a recovery rate of about 90% of Cr(VI). © Copyright 2010, Mary Ann Liebert, Inc. 2010.

  20. Bicarbonate Impact on U(VI) Bioreduction in a Shallow Alluvial Aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Long, Philip E.; Williams, Kenneth H.; Davis, James A.; Fox, Patricia M.; Wilkins, Michael J.; Yabusaki, Steven B.; Fang, Yilin; Waichler, Scott R.; Berman, Elena S.; Gupta, Manish; Chandler, Darrell P.; Murray, Christopher J.; Peacock, Aaron D.; Giloteaux, L.; Handley, Kim M.; Lovley, Derek R.; Banfield, Jillian F.

    2015-02-01

    Field-scale biostimulation and desorption tracer experiments conducted in a uranium (U) contaminated, shallow alluvial aquifer have provided insight into the coupling of microbiology, biogeochemistry, and hydrogeology that control U mobility in the subsurface. Initial experiments successfully tested the concept that Fe-reducing bacteria such as Geobacter sp. could enzymatically reduce soluble U(VI) to insoluble U(IV) during in situ electron donor amendment (Anderson et al. 2003, Williams et al. 2011). In parallel, in situ desorption tracer tests using bicarbonate amendment demonstrated rate-limited U(VI) desorption (Fox et al. 2012). These results and prior laboratory studies underscored the importance of enzymatic U(VI)-reduction and suggested the ability to combine desorption and bioreduction of U(VI). Here we report the results of a new field experiment in which bicarbonate-promoted uranium desorption and acetate amendment were combined and compared to an acetate amendment-only experiment in the same experimental plot. Results confirm that bicarbonate amendment to alluvial aquifer desorbs U(VI) and increases the abundance of Ca-uranyl-carbonato complexes. At the same time, that the rate of acetate-promoted enzymatic U(VI) reduction was greater in the presence of added bicarbonate in spite of the increased dominance of Ca-uranyl-carbonato aqueous complexes. A model-simulated peak rate of U(VI) reduction was ~3.8 times higher during acetate-bicarbonate treatment than under acetate-only conditions. Lack of consistent differences in microbial community structure between acetate-bicarbonate and acetate-only treatments suggest that a significantly higher rate of U(VI) reduction the bicarbonate-impacted sediment may be due to a higher intrinsic rate of microbial reduction induced by elevated concentrations of the bicarbonate oxyanion. The findings indicate that bicarbonate amendment may be useful in improving the engineered bioremediation of uranium in aquifers.

  1. 朝特Ⅵ多效复合种衣剂在玉米上的应用效果%Study on Application of Chaote VI Pleiotrooic Comoound Seed Coating in Maize

    Institute of Scientific and Technical Information of China (English)

    王俊国

    2011-01-01

    [ Objective ] The aim was to study the application effect of Chaote VI pleiotropic compound seed coating agent in maize production,and provide effective measures for drought resistant, increasing yield of maize. [ Method ] Chaote VI pleiotropie compound seed coating agent was adopted to carry on coating and without coating treatment of maize seeds, the soil moisturem growth status and yield of coating and without coating maize in growth period was compared and observed. [ Result ] Maize seed coating absorb water and resistant of drought, 27 % of early emergency rate, increasing emergency rate 19%, plant height in 3-leaf stage increased 1.4 cm, stem diameter increased 0.1 em, root length increased 1.6 cm, roots increased 2.5, root weight 2.4 g; in jointing period, average plant height increased 2.7 cm, stem diameter 0.1 cm,average leaf area per plant 126.4 cm2; insect pest decreased 12 %, yield average increased 14.9%. [Conclusion] Chaote Ⅵ pleiotropic compound seed coating agent is appropriately generalized in drought area of Liaoxi for it can storing water, increasing seed vigor, increasing emergency rate.%[目的]探讨朝特Ⅵ多效复合种衣剂在玉米生产中的应用效果,为玉米抗旱保苗增产提供有效措施.[方法]采用朝特Ⅵ多效复合种衣剂对玉米种子进行包衣与不包衣处理,对包衣玉米与未包衣玉米生育期土壤水分、生长状况及产量进行对比观测.[结果]玉米种子包衣吸水抗旱,提早出苗率27%,提高出苗率19%,3叶期株高平均增加1.4 cm,茎粗平均增加0.1 cm,根长增加1.6 cm,根系多2.5条,根重多2.4 g;拔节期平均株高增加2.7 cm,茎粗增加0.1 cm,平均每株叶面积增加126.4 cm2;虫害减少12个百分点,平均增产14.9%.[结论]朝特Ⅵ多效复合种衣剂具有蓄水保墒、提高种子活力、防止芽干、增加出苗率的效果,适合在辽西干旱地区推广.

  2. Bioreduction of U(VI) and stability of immobilized uranium under suboxic conditions.

    Science.gov (United States)

    Hu, Nan; Ding, De-xin; Li, Shi-mi; Tan, Xiang; Li, Guang-yue; Wang, Yong-dong; Xu, Fei

    2016-04-01

    In order to study the bioreduction of U(VI) and stability of immobilized uranium under suboxic conditions, microcosm were amended with ethanol, lactate and glucose, and incubated under suboxic conditions. During the incubation, total dissolved U in amended microcosms decreased from 0.95 mg/L to 0.03 mg/L. Pyrosequencing results showed that, the proportion of anaerobic microorganisms capable of reducing U(VI) under suboxic conditions was small compared with that under anoxic conditions; the proportion of aerobic and facultative anaerobic microorganisms capable of consuming the dissolved oxygen was large; and some of the facultative anaerobic microorganisms could reduce U(VI). These results indicated that different microbial communities were responsible for the bioreduction of U(VI) under suboxic and anoxic conditions. After the electron donors were exhausted, total dissolved U in the amended microcosms remained unchanged, while the U(VI)/U(IV) ratio in the solid phase of sediments increased obviously. This implied that the performance of bioreduction of the U(VI) can be maintained under suboxic condition.

  3. Inhibition of bone resorption by Tanshinone VI isolated from Salvia miltiorrhiza Bunge

    Directory of Open Access Journals (Sweden)

    V. Nicolin

    2010-05-01

    Full Text Available During the last decade, a more detailed knowledge of molecular mechanisms involved in osteoclastogenesis has driven research efforts in the development and screening of compound libraries of several small molecules that specifically inhibit the pathway involved in the commitment of the osteoclast precursor cells. Natural compounds that suppress osteoclast differentiation may have therapeutic value in treating osteoporosis and other bone erosive diseases such as rheumatoid arthritis or metastasis associated with bone loss. In ongoing investigation into anti-osteoporotic compounds from natural products we have analyzed the effect of Tanshinone VI on osteoclasts differentiation, using a physiologic three-dimensional osteoblast/bone marrow model of cell co-culture. Tanshinone VI is an abietane diterpene extracted from the root of Salvia miltiorrhiza Bunge (Labiatae, a Chinese traditional crude drug, ‘’Tan-Shen’’. Tashinone has been widely used in clinical practice for the prevention of cardiac diseases, arthritis and other inflammation-related disorders based on its pharmacological actions in multiple tissues. Although Tanshinone VI A has been used as a medicinal agent in the treatment of many diseases, its role in osteoclast-related bone diseases remains unknown. We showed previously that Tanshinone VI greatly inhibits osteoclast differentiation and suppresses bone resorption through disruption of the actin ring; subsequently, we intended to examine the precise inhibitory mechanism of Tanshinone VI on osteoclast differentiating factor. This study shows, for the first time, that Tanshinone VI prevents osteoclast differentiation by inhibiting RANKL expression and NFkB induction.

  4. Biosorption of Cr(VI)_ and Cr(III)_Arthrobacter species

    CERN Document Server

    Gelagutashvili, E; Gurielidze, M

    2011-01-01

    The biosorption of Cr(VI)_ and Cr(III)_ Arthrobacter species (Arthrobacter globiformis and Arthrobacter oxidas) was studied simultaneous application dialysis and atomic absorption analysis. Also biosorption of Cr(VI) in the presence of Zn(II) during growth of Arthrobacter species and Cr(III) in the presence of Mn(II) were discussed. Comparative Cr(VI)_ and Cr(III)_ Arthrobacter species shown, that Cr(III) was more effectively adsorbed by both bacterium than Cr(VI). The adsorption capacity is the same for both the Chromium-Arthrobacter systems. The biosorption constants for Cr(III) is higher than for Cr(VI) 5.7-5.9- fold for both species. Comparative Freundlich biosorption characteristics Cr(VI) Arthrobacter species of living and dry cells shown, that capacity(n) is in both cases the same(1.25,1.35). Dry cells have larger biosorption constant for both species, than living cells. Biosorption characteristics (K) and (n) for A. oxidas are without Mn(II) and in the presence of Mn(II) 2.6 x 10-4 (K), 1.37 (n) and 2...

  5. Characterizing toxic Cr(VI) contamination in chromite mine overburden dump and its bacterial remediation.

    Science.gov (United States)

    Dhal, B; Das, N N; Thatoi, H N; Pandey, B D

    2013-09-15

    Cr(VI) generated due to natural oxidation of chromite mineral present in chromite mine overburden (COB) dumps of Sukinda, India, has been characterized by different physico-chemical methods. The Cr(VI) was found to be associated with goethite matrix at a contamination level of 500 mg Cr(VI)kg(-1) of COB. Bacillus sp. isolated from the overburden sample exhibiting high tolerance to the hexavalent chromium, was used for the remediation of Cr(VI) in the overburden. The process was optimized while varying the parameters such as pH (2-9), pulp density (10-60%) and temperature (25-40 °C). Optimal reduction of more than 98% of Cr(VI) in the COB sample was achieved in 16 h at pH∼7.0 and 60% pulp density with the Bacillus sp. (4.05 × 10(7)cells mL(-1)) in absence of media. The exponential rate equation yielded rate constant value of 2.14 × 10(-1)h(-1) at 60% pulp density. The mode of bio-reduction of Cr(VI) in the overburden sample was established by FT-IR, XRD, EPMA and SEM-EDS studies.

  6. Characteristics of Amine Surfactant Modified Peanut Shell and Its Sorption Property for Cr(VI)

    Institute of Scientific and Technical Information of China (English)

    岳敏; 张猛; 刘斌; 许醒; 李小明; 岳钦艳; 马春元

    2013-01-01

    Modified peanut shell (MPS) was prepared by amination reaction with peanut shell (PS) as the starting material. The sorption of Cr(VI) oxyanions on MPS in static and column tests were investigated. In addition, the sorption isotherm and kinetic models were applied to confirm the sorption capacity and the sorption mechanisms. BET surface area analysis showed the physicochemical characteristics of the samples. The results of zeta potential, Fourier transform infrared (FT-IR) and Raman spectra analysis illustrated that chemical adsorption and ion ex-change are the potential sorption mechanism. The static sorption test showed that the maximum sorption capacity (qmax) of MPS for Cr(VI) increased with temperature, which indicated that the Cr(VI) sorption process was endo-thermic. The saturated sorption capacity of Cr(VI) in the column sorption test was 138.34 mg·g-1, which accounted for 93.9%of the qmax at 25 °C. The regeneration capacity of MPS was evaluated using HCl solution as an eluent. The high regeneration efficiency (82.6%) validated the dominance of the ion exchange mechanism in the Cr(VI) sorption process with Cl-ions displacing Cr(VI) oxyanion on MPS. The Langmuir isotherm model showed a higher correlation coefficient than the other adsorption isotherm models. And in the kinetic study, a pseudo-second-order model fit the data best.

  7. Reduction of chromium (VI by the indirect action of Thiobacillus thioparus

    Directory of Open Access Journals (Sweden)

    E. Donati

    2003-03-01

    Full Text Available The microbial reduction of chromium(VI to chromium(III has been one of the most widely studied forms of metal bioremediation. Recently, we have found that Thiobacillus ferrooxidans and Thiobacillus thiooxidans, growing on elemental sulphur, can indirectly promote chromium(VI reduction by producing reducing agents such as sulphite and thiosulphate, which abiotically reduce chromium(VI. Those species of Thiobacillus are acidophilic bacteria which grow optimally at pH values lower than 4. However, most of those reducing agents are stabilised at higher pH values. Thus, the present paper reports on the ability to reduce chromium(VI using another specie of Thiobacilli, Thiobacillus thioparus, which is able to grow at pH close to 7.0. T. thioparus cultures were carried out in a fermentation vessel containing medium and sulphur as the sole energy source and maintained at 30ºC and 400 rpm. The pH was adjusted to 6.0, 7.0 or 8.0 and maintained with the automatic addition of KOH. Our results show high chromium (VI reduction values (close to 100% at the end of bacterial growth at the three pH values. The results of these experiments are very promising for development of a microbiological process to be used in the detoxification of chromium(VI-polluted effluents.

  8. Efficient sorption and reduction of U(VI) on zero-valent iron-polyaniline-graphene aerogel ternary composite.

    Science.gov (United States)

    Chen, Lili; Feng, Shaojie; Zhao, Donglin; Chen, Shaohua; Li, Feifei; Chen, Changlun

    2017-03-15

    In this work, zero-valent iron-polyaniline-graphene aerogel composite (Fe-PANI-GA) was prepared and applied in the removal of U(VI) from aqueous solutions by batch sorption experiments. The experimental results showed that the Fe-PANI-GA composite had an excellent removal capacity for the removal of U(VI) in acidic solutions. The results also showed that the maximum removal capacity of the Fe-PANI-GA toward U(VI) was 350.47mg/g at pH 5.5. The sorption kinetics data were well-described by pseudo-second-order. The sorption isotherms of U(VI) fitted well with Langmuir isotherm and exhibited better removal efficiency with the increase of temperature. The thermodynamic parameters (ΔG, ΔS, ΔH) indicated that the sorption of U(VI) on the Fe-PANI-GA was an endothermic and spontaneous process. Moreover, removal mechanisms were studied based on the results of XRD, FTIR and XPS. Both U(VI) sorption and partially reductive precipitation of U(VI) to U(IV) contributed to the removal of U(VI) on Fe-PANI-GA. Therefore, Fe-PANI-GA was an economic and effective material for the removal of uranium from nuclear waste in practical application.

  9. Effect of Cr(VI) concentration on gas and particle production during iron oxidation in aqueous solutions containing Cl(-) ions.

    Science.gov (United States)

    Ahn, Hyangsig; Jo, Ho Young; Ryu, Ji-Hun; Koh, Yong-Kwon

    2017-02-01

    Zero-valent iron (ZVI) is commonly used as a medium in permeable reactive barriers (PRBs) because of its high reducing ability. The generation of H2 gas in PRBs, however, can decrease the permeability of PRBs and reduce the contact area between the PRB and contaminated groundwater. This study investigated the effect of the initial Cr(VI) concentration ([Cr(VI)init]) in aqueous solutions containing Cl(-) ions on the generation of H2 gas. ZVI chips were reacted in reactors with 0.5-M NaCl solutions with [Cr(VI)init] ranging between 51 and 303 mg/L. The initial pH was set at 3. The oxidation of ZVI chips by Cr(VI) in aqueous solutions containing Cl(-) ions produced H2 gas and particles (Fe(III)-Cr(III)(oxy)hydroxides). The Cr(VI) removal from aqueous solutions increased as the [Cr(VI)init] increased, as did H2 gas generation. The positive effect of [Cr(VI)init] on H2 gas generation might be due to an increase in the redox potential gradient as [Cr(VI)init] increases. This increased gradient would enhance H(+) ion penetration through the passive film (Fe(III)-Cr(III)(oxy)hydroxides), which formed on the ZVI surface, by diffusion from the solution to pits beneath the passive film.

  10. Box-Behnken experimental design for chromium(VI) ions removal by bacterial cellulose-magnetite composites.

    Science.gov (United States)

    Stoica-Guzun, Anicuta; Stroescu, Marta; Jinga, Sorin Ion; Mihalache, Nicoleta; Botez, Adriana; Matei, Cristian; Berger, Daniela; Damian, Celina Maria; Ionita, Valentin

    2016-10-01

    In this study bacterial cellulose-magnetite composites were synthesised for the removal of chromium(VI) from aqueous solutions. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis and X-ray Photoelectron Spectroscopy (XPS) were used to characterize the bacterial cellulose-magnetite composites and to reveal the uniform dispersion of nanomagnetite in the BC matrix. Magnetic properties were also measured to confirm the magnetite immobilization on bacterial cellulose membrane. The effects of initial Cr(VI) concentration, solution pH and solid/liquid ratio upon chromium removal were examined using the statistical Box-Behnken Design. Because of the possibility of magnetite dissolution during chromium(VI) adsorption, the degree of iron leaching was also analysed in the same conditions as Cr(VI) adsorption. From the factors affecting chromium(VI) adsorption the most important was solution pH. The highest Cr(VI) removal efficiency was observed at pH 4, accompanied by the lowest iron leaching in the solution. The adsorption experiments also indicated that the adsorption process of chromium(VI) is well described by Freundlich adsorption model. Our results proved that the BC-magnetite composites could be used for an efficient removal of chromium(VI) from diluted solutions with a minimum magnetite dissolution during operation.

  11. Development of mathematical models for insitu bioremediation of Cr(VI) contaminated Aquifers

    Science.gov (United States)

    Vairavan, S.; Philip, L.; Bhallamudi, M. S.

    2009-12-01

    Hexavalent Chromium (Cr(VI)) is a contaminant of significant concern due to its carcinogenic and mutagenic property in mammals. Cr(VI) abatement in aquifers can be achieved by reducing chromium from its hexavalent state to trivalent state because Cr(III) is less toxic, insoluble and immobile compared to Cr(VI). Reduction of Cr(VI) by Fe(II)/S2- present in mineral deposits followed by precipitation as hydroxides and/or sulfides and adsorption of Cr(VI) over mineral deposits in the geological formations are predominant mechanisms which account for the natural attenuation of Cr(VI) inside an aquifer. Once the Cr(VI) concentration goes beyond the carrying capacity of the aquifer, it can be cleaned by constructing a Permeable Reactive Barrier (PRB) perpendicular to the direction of the flow of groundwater or by introducing Injection Wells (IW) along the direction of flow. In both the above mentioned cases addition of chemical reductants results in high costs. On the other hand, bacterial biotransformation of Cr(VI) in presence of organic matter seems to be a viable and eco friendly option for remediation of chromium contaminated aquifers. Enhancement of biotransformation of hexavalent chromium is expected in the presence of soil microbes such as Sulfate Reducing Bacteria (SRB) and Iron Reducing Bacteria (IRB) along with Chromium Reducing Bacteria (CRB). Groundwater usually contains sulfate and iron (dissolution from the mineral deposits) which can act as electron acceptor for IRB and SRB metabolism and yield biogenic reductants such as Fe2+, and S2- which abiotically reduce Cr(VI) to Cr(III). The objective of the present work is to understand the effect of different electron acceptors on Cr(VI) reduction and to model the fate and transport of Cr(VI) in an aquifer. Batch studies were conducted to estimate biokinetic parameters such as maximum specific growth rate (µmax), half saturation constant (Ks), yield coefficient (YT) and inhibition constant (Ki). Transformation

  12. Hvem er vi? Hvem er de?

    DEFF Research Database (Denmark)

    Kryger, Niels

    2016-01-01

    Kommentaren tager afsæt i initiativer i de pædagogiske faglige foreninger i Europa EERA) og i Norden (NERA) og argumenterer for at det er forpligtelse for os som nordiske og europæiske pædagogiske forskere at gå op imod de stadigt mere ekskluderende vi-konstruktioner, som er blevet formuleret i f...

  13. O vi in the local interstellar medium

    CERN Document Server

    Barstow, M A; Welsh, B Y; Lallement, R; Preval, J K Barstow A E Forbes And S

    2010-01-01

    We report the results of a search for O VI absorption in the spectra of 80 hot DA white dwarfs observed by the FUSE satellite. We have carried out a detailed analysis of the radial velocities of interstellar and (where present) stellar absorption lines for the entire sample of stars. In approximately 35% of cases (where photospheric material is detected), the velocity differences between the interstellar and photospheric components were beneath the resolution of the FUSE spectrographs. Therefore, in 65% of these stars the interstellar and photospheric contributions could be separated and the nature of the O VI component unambiguously determined. Furthermore, in other examples, where the spectra were of a high signal-to-noise, no photospheric material was found and any O VI detected was assumed to be interstellar. Building on the earlier work of Oegerle et al. (2005) and Savage & Lehner (2006), we have increased the number of detections of interstellar O VI and, for the first time, compared their locations...

  14. 29 CFR 1910.1026 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... activity involving chromium cannot release dusts, fumes, or mists of chromium (VI) in concentrations at or... currents that prevent the LEVs from performing efficiently. The use of fans has a similar effect. Industry... and positioning of cross drafts, fans, doors, windows, partitions and process equipment that...

  15. Role of RpoS in fine-tuning the synthesis of Vi capsular polysaccharide in Salmonella enterica serotype Typhi.

    Science.gov (United States)

    Santander, Javier; Wanda, Soo-Young; Nickerson, Cheryl A; Curtiss, Roy

    2007-03-01

    Regulation of the synthesis of Vi polysaccharide, a major virulence determinant in Salmonella enterica serotype Typhi, is under the control of two regulatory systems, ompR-envZ and rscB-rscC, which respond to changes in osmolarity. Some serotype Typhi strains exhibit overexpression of Vi polysaccharide, which masks clinical detection of lipopolysaccharide O antigen. This variation in Vi polysaccharide and O antigen display (VW variation) has been observed since the initial studies of serotype Typhi. In this study, we report that rpoS plays a role in this increased expression in Vi polysaccharide. We constructed a variety of isogenic serotype Typhi mutants that differed in their expression levels of RpoS and examined the role of the rpoS product in synthesis of Vi polysaccharide under different osmolarity conditions. Vi polysaccharide synthesis was also examined in serotype Typhi mutants in which the native promoter of the rpoS was replaced by an araCP(BAD) cassette, so that the expression of rpoS was arabinose dependent. The RpoS(-) strains showed increased syntheses of Vi polysaccharide, which at low and medium osmolarities masked O antigen detection. In contrast, RpoS(+) strains showed lower syntheses of Vi polysaccharide, and an increased detection of O antigen was observed. During exponential growth, when rpoS is unstable or present at low levels, serotype Typhi RpoS(+) strains overexpress the Vi polysaccharide at levels comparable to those for RpoS(-) strains. Our results show that RpoS is another regulator of Vi polysaccharide synthesis and contributes to VW variation in serotype Typhi, which has implications for the development of recombinant attenuated Salmonella vaccines in humans.

  16. EXAFS investigation on U(VI) immobilization in hardened cement paste. Influence of experimental conditions on speciation

    Energy Technology Data Exchange (ETDEWEB)

    Mace, N.; Wieland, E.; Daehn, R.; Tits, J. [Paul Scherrer Inst. (PSI), Villigen (Switzerland). Lab. for Waste Management; Scheinost, A.C. [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Inst. of Resource Ecology; Rossendorf Beamline (ROBL), Grenoble (France). ESRF

    2013-08-01

    Extended X-ray absorption fine structure (EXAFS) spectroscopy has been used to investigate the coordination environment of U(VI) in cementitious materials. The EXAFS measurements were carried out on U(VI)-doped samples prepared under varying conditions, such as samples from sorption, hydration and diffusion experiments, and using different cementitious materials, such as crushed hydrated hardened cement paste (HCP) and calcium silicate hydrates (C-S-H). The samples had U(VI) loadings ranging from 1700 {mu}g/g to 45000 {mu}g/g. Applying principal component analysis (PCA) on 13 EXAFS spectra (each spectra corresponding to a minimum of five different scans) of the low loading samples, one single species is obtained indicating a similar U(VI) coordination environment for both HCP and C-S-H samples. This result confirms that C-S-H phases control the uptake of U(VI) in the complex cement matrix. The coordination environment structure of this species is similar to a U(VI) surface complex or to U(VI) in uranyl silicate minerals (two axial O atoms at 1.82 {+-} 0.02 A; four equatorial O atoms at 2.25 {+-} 0.01 A; one Si atom at 3.10 {+-} 0.03 A). At high U(VI) loading, PCA revealed a second U(VI) species, with a coordination environment similar to that of U(VI) in calcium uranate (two axial O atoms at 1.94 {+-} 0.04 A; five equatorial O atoms at 2.26 {+-} 0.01 A; four Ca atoms at 3.69 {+-} 0.05 A and five U atoms at 3.85 {+-} 0.04 A). This study suggest that, at low U(VI) loading, U(VI) is bound to C-S-H phases in HCP while at high U(VI) loading, the immobilization of U(VI) in cementitious materials is mainly controlled by the precipitation of a calcium uranate-type phase. (orig.)

  17. Biosensing and bioremediation of Cr(VI) by cell free extract of Enterobacter aerogenes T2.

    Science.gov (United States)

    Panda, Jigisha; Sarkar, Priyabrata

    2014-01-01

    Hexavalent chromium or Cr(VI) enters the environment through several anthropogenic activities and it is highly toxic and carcinogenic. Hence it is required to be detected and remediated from the environment. In this study, low-cost and environment-friendly methods of biosensing and bioremediation of Cr(VI) have been proposed. Crude cell free extract (CFE) of previously isolated Enterobacter aerogenes T2 (GU265554; NII 1111) was prepared and exploited to develop a stable biosensor for direct estimation of Cr(VI) in waste water, by using three electrodes via cyclic voltammetry. For bioremediation studies, a homogeneous solution of commercially available sodium alginate and CFE was added dropwise in a continuously stirred calcium chloride solution. Biologically modified calcium alginate beads were produced and these were further utilized for bioremediation studies. The proposed sensor showed linear response in the range of 10-40 μg L(-1) Cr(VI) and the limit of detection was found to be 6.6 μg L(-1) Cr(VI). No interference was observed in presence of metal ions, e.g., lead, cadmium, arsenic, tin etc., except for insignificant interference with molybdenum and manganese. In bioremediation studies, modified calcium alginate beads showed encouraging removal rate 900 mg Cr(VI)/m(3) water per day with a removal efficiency of 90%, much above than reported in literature. The proposed sensing system could be a viable alternative to costly measurement procedures. Calcium alginate beads, modified with CFE of E. aerogenes, could be used in bioremediation of Cr(VI) since it could work in real conditions with extraordinarily high capacity.

  18. Simplest identification, O-specific polysaccharide purification and antigenic evaluation of Salmonella enterica serovar Typhi Vi negative isolate.

    Science.gov (United States)

    Salman, Muhammad; Ali, Aamir; Jabbar, Abdul; Sarwar, Yasra; Rahman, Moazur; Iqbal, Mazhar; Haque, Abdul

    2015-01-01

    Currently licensed typhoid vaccines are based on Vi capsular polysaccharides. Recent molecular reports from typhoid endemic countries state that Salmonella enterica serovar Typhi (S. Typhi) Vi negative strains occur naturally and cause typhoid fever which is indistinguishable from disease caused by Vi positive strains. Vaccine based on Vi polysaccharide may not protect patients if the invading S. Typhi are negative for Vi. The lipopolysaccharide (LPS) is an essential component of S. Typhi outer membrane in which O-specific polysaccharide (OSP) is a protective antigen and universal candidate for vaccine development. In this study, S. Typhi Vi negative isolates were discriminated from Vi positive isolates through a duplex PCR using primers of fliC-d (599bp) and tviA (495bp) genes. The LPS of S. Typhi Vi negative isolates was extracted by hot phenol method and OSP was purified by core hydrolysis. The yield of extracted LPS was 91 mg/L and that of purified OSP was 49.14 mg/L of culture broth. LPS showed ladder like appearance by zinc imidazole staining following SDS-PAGE. Whole cell challenged mice sera were used for in vitro antigenicity evaluation of the purified LPS and OSP. The antigenicity was found adequate by immunodiffusion assay. To our knowledge, this is the first report of purification and antigenic evaluation of LPS of a Vi negative S. Typhi isolate. The purified OSP from S. Typhi Vi negative isolate may be coupled with a carrier protein to produce universal low cost conjugate vaccine candidates for use in typhoid endemic regions.

  19. Valoração de contingente pelas modelagens logit e análise multivariada: um estudo de caso da disposição a aceitar compensação dos cafeicultores vinculados ao PRO-CAFÉ de Viçosa - MG Contingent valuation with modeling logit and multivariate analyses: a case study of the willingness of coffee planters linked to the PRO-COFFEE of Viçosa - MG to accept compensation

    Directory of Open Access Journals (Sweden)

    Pedro Silveira Máximo

    2009-12-01

    Full Text Available O objetivo deste estudo foi, justamente, identificar, entre os métodos LOGIT e a análise multivariada, qual a mais eficaz para estimar a Disposição a Aceitar Compensação (DAC dos cafeicultores quando o viés da utilidade marginal é passível de ocorrência. Para tal, foi elaborado um formulário com 33 perguntas envolvendo informações sobre características socioeconômicas dos cafeicultores, o uso da metodologia de valoração de contingente (MVC e do veículo de pagamento dos "Jogos de Lances", que revelou a Disposição a Aceitar uma Compensação (DAC na troca de um hectare de café por um hectare de mata. Como esperado, por causa do viés da utilidade marginal o método LOGIT foi incapaz de produzir resultados consistentes. Já a estimação da DAC pela análise multivariada mostrou que, caso o governo estivesse disposto a aumentar a provisão de mata em 70 ha, ele deveria despender 254.200 reais por ano, tratando apenas dos cafeicultores vinculados ao programa do PRO-CAFÉ.The object of this study was to identify which method, either LOGIT or multivariate analyses, was the most efficient to estimate the coffee planters' Willingness to Accept a Compensation, when there was a possibility of occurrence of marginal utility. For such, a questionnaire was formulated, with 33 questions involving information on coffee planters' socio - economic characteristics, the use of the methodology of contingent valuation (MCV, and the payment of the "offer game" that reveled the willingness to accept a compensation (WAC, by exchanging a hectare of coffee by a hectare of forest. As expected, because of the marginal utility's bias, the LOGIT method was unable to produce consistent results. However, when the WAC was estimated by multivariate analyses, the results showed that if the government is willing to increase the provision of forest to 70 hectares, it should pay out 254,200 reais (around 116,000 dollars, dealing only with the coffee planters

  20. Modern Science and practice of scientists: a study from the discourses and routines of the researchers of the Centre of Agricultural Sciences of the Federal University of ViçosaCiência moderna e prática dos cientistas: um estudo a partir dos discursos e das rotinas dos pesquisadores do Centro de Ciências Agrárias da Universidade Federal de Viçosa

    Directory of Open Access Journals (Sweden)

    Fernanda Henrique Cupertino Alcantara

    2010-12-01

    Full Text Available Este estudo objetivou discutir o processo de assimilação da Ciência e seus produtos na vida social, a partir do advento da modernidade, e apresenta alguns dos discursos a respeito da sua função emancipadora e as posteriores reações críticas a estes discursos. Utiliza-se, como ilustração, uma análise aos discursos e às rotinas de pesquisadores dos programas de pós-graduação stricto sensu do Centro de Ciências Agrárias da Universidade Federal de Viçosa (CCA/UFV. Para tal, como procedimento metodológico, além de profundo levantamento bibliográfico, foi entrevistada uma amostra representativa de 68 pesquisadores do CCA/UFV. Com base nas averiguações feitas, verificou-se que os conhecimentos científicos produzidos pelos pesquisadores do CCA/UFV estão em consonância com as lógicas da Ciência moderna, pois, além de haver uma grande especialização dos cientistas, o setor produtivo exerce importante influência em suas práticas e rotinas.This study aimed to discuss the process of incorporating Science and its products in the social sphere from the advent of modernity, presenting some of the discourses on their emancipatory function and subsequent critical reactions to these discourses. An analysis of the discourses and routines of researchers of strictu sensu post-graduate programs of the Center for Agricultural Sciences of the Federal University of Viçosa (CCA / UFV was used as an example. The methodological procedure was conducted as interviews for a representative sample of 68 researchers from the CCA/UFV. Based on the inquiries made, it was found that the knowledge produced by researchers at CCA/UFV is consistent with the logic of modern Science. Besides having highly specialized scientists, the productive sector has an important influence on the practices and routines of the researchers.

  1. Molybdenum(VI) coordination chemistry of the N,N-disubstituted bis(hydroxylamido)-1,3,5-triazine ligand, H2bihyat. Water-assisted activation of the Mo(VI)═O bond and reversible dimerization of cis-[Mo(VI)O2(bihyat)] to [Mo(VI)2O4(bihyat)2(H2O)2].

    Science.gov (United States)

    Stylianou, Marios; Nikolakis, Vladimiros A; Chilas, George I; Jakusch, Tamas; Vaimakis, Tiverios; Kiss, Tamas; Sigalas, Michael P; Keramidas, Anastasios D; Kabanos, Themistoklis A

    2012-12-17

    dinuclear molybdenum(VI) species, vibrational spectra, and energetics of the metal-ligand interaction for the three molybdenum(VI) compounds 1-3 have been studied by means of density functional theory calculations.

  2. A contribution to the study of the extraction of mineral acids and of actinide (IV) and (VI) cations by N,N-dialkylamides; Contribution a l'etude de l'extraction d'acides mineraux et de cations actinides aux degres d'oxydation (IV) et (VI) par des N,N-dialkylamides

    Energy Technology Data Exchange (ETDEWEB)

    Condamines, N.

    1990-03-15

    N,N-dialkylamides are alternate extractants to tributylphosphate, TBP, for the actinides separation in nuclear fuel reprocessing. N,N-di (2-ethyl hexyl) butyramide and N,N-di (2 ethyl hexyl) isobutyramide are selected for their sufficient extraction and partition ability towards actinides (IV) and (VI) without coextracting fission products. Mechanisms of HNO{sub 3}, UO{sub 2}{sup 2+}, Pu{sup 4+}, Th{sup 4+} are investigated. Nitric acid extraction is due to the competitive formation of the species (HNO{sub 3})L{sub 2}, (HNO{sub 3})L, (HNO{sub 3}){sub 2}L (L: DOBA or DOiBA). An hydrogen bond is the driving force of the transfer. For low acidity media, amides are neutral extractants. Physical interactions, between free ligand and metallic complex, arise for high amide concentrations. Taking into account the non-ideality of the organic medium by a hard spheres mixture model, we estimate that such interactions are far from negligible and very specific to the amide group. Unlike TBP, when increasing acidity, amides behave as anionic extractants. DOBA and DOiBA appear to be satisfactory extractants for fuel reprocessing.

  3. Estudo das propriedades do pseudofruto do cajueiro na adsorção de Cr (VI

    Directory of Open Access Journals (Sweden)

    Thiago C. Medeiros

    2013-11-01

    Full Text Available Study of the cashew properties for Cr (VI adsorptionIn this study, the Cr(VI adsorption properties by cashew (Anacardium occidentale L. were studied in a batch system. The effects of pH (5.0 and 7.0, drying process – S (oven-dried and lyophilized, particle size – P (0.10 – 0.25 and 0.25 – 0.84 mm, mass of adsorbent – m (1.0 and 1.5 g initial chromium concentration – C (500 and 1000 mg L-1 contact time – t (1 and 3 h and stirring rate – v (0 and 150 rpm, on the adsorption process were studied using a fractional factorial design (27-4. Under ideal conditions the efficiency of adsorption of 87.24% for total chromium and 100.00% for Cr (VI were achieved. The maximum adsorption capacity achieved was 11.43 mg/g. The adsorbent was characterized by infrared and X-ray fluorescence spectroscopy. Test reactions performed with Cr(VI in conjunction with the aqueous extract of the adsorbent and pH monitoring during adsorption were carried out to better understand the mechanisms of adsorption. The proposed mechanism consists of two steps: reduction of Cr(VI in solution or at the surface of the adsorbent, and subsequent adsorption of Cr(III by ion exchange or complexation.

  4. Hvor skal vi hen, du?

    DEFF Research Database (Denmark)

    Brok, Helle

    2014-01-01

    concerning “applied science” the small organization “The study of Psychomotor Therapy” has become a de-partment in VIA University College. Over the last 8 years the department has been through a major transformation from being an independent organization with 5 employees and 80 students to being a part...... of the process of study with the aim to increase the number of students to fulfill the study. Perspective The study suggest that strategies “born” by employees in Psychomotor Therapy can be included and have influence on the large organization VIA university college as well as the strategies of the larger...... influence on the employees and makes a large pressure and stress related experiences. Another challenge is the low number of students that fulfill the study. This knowledge leads to 3 points of strategies for the forthcoming years: 1. Human resources management strategy with the aim to consolidate and grow...

  5. MyD88-dependent pro-inflammatory activity in Vi polysaccharide vaccine against typhoid promotes Ab switching to IgG.

    Science.gov (United States)

    Garg, Rohini; Akhade, Ajay Suresh; Yadav, Jitender; Qadri, Ayub

    2015-10-01

    Vi capsular polysaccharide is currently in use as a vaccine against human typhoid caused by Salmonella Typhi. The vaccine efficacy correlates with IgG anti-Vi Abs. We have recently reported that Vi can generate inflammatory responses through activation of the TLR2/TLR1 complex. In the present study, we show that immunization with Vi produces IgM as well as IgG Abs in wild type mice. This ability is not compromised in mice deficient in T cells. However, immunization of mice lacking the TLR adaptor protein, MyD88, with Vi elicits only IgM Abs. These results suggest that MyD88-dependent pro-inflammatory ability of the Vi vaccine might be vital in generating IgG Abs with this T-independent Ag.

  6. Synergistic extraction of U(VI) and Th(IV) from nitric acid media withHBMPPT and TBP in toluene

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The synergistic extraction of U(VI) and Th(IV) from nitric acid solutionby HBMPPT (4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione) andTBP (tributylphosphate ) in toluene was studied. The extraction abilityof HBMPPT for U(VI) and Th(IV) was not so high, but when a little TBP was added in, theability to extract U(VI) and Th(IV) was improved. The extracted complexes may be presented as UO2NO3.BMPPT.TBP and UO2(BMPPT)2 .TBP for U(VI), and Th(NO3)3.BMPPT.TBP andTh(NO3)2 (BMPPT)2.TBP for Th(IV),respectively, in the synergisticextraction system. The synergistic effect of HBMPPT and TBP makes the separationcoefficient of U(VI) /Th(IV) or U(VI)/Eu(III) reach a high value.

  7. Adsorption of chromium ion (VI) by acid activated carbon

    OpenAIRE

    A. A. Attia; Khedr,S. A.; Elkholy,S. A.

    2010-01-01

    The activated carbon produced from olive stones was chemically activated using sulfuric acid, (OS-S), and utilized as an adsorbent for the removal of Cr(VI) from aqueous solution in the concentration range 4-50 mg/L. Adsorption experiments were carried out in a batch process and various experimental parameters such as effect of contact time, initial chromium ion concentration, carbon dosage, and pH on percentage removal have been studied. Adsorption results obtained for activated carbon (OS-S...

  8. A uranium (VI) complex: Synthesis, structural and thermal kinetic analysis

    Science.gov (United States)

    Goel, Nidhi

    2016-08-01

    A new complex [UO2(2,6-DNP)2phen] (1) (2,6-DNP = 2,6-dinitrophenol, phen = 1,10-phenanthroline) was synthesized, and identified by elemental analysis, IR, Powder XRD and single crystal X-ray crystallography. Crystal structure provides the abundant information's about the bonding and geometry around the U(VI) metal center. The thermal decomposition was studied by TG-DSC, and the kinetics of thermolysis was investigated by applying model fitting as well as isoconversional methods. Explosion delay measurement (De) was also evaluated to determine the response of this complex under the condition of rapid heating.

  9. Final Technical Report -- GEO-VI - USGEO

    Energy Technology Data Exchange (ETDEWEB)

    Hirsch, Leonard

    2009-11-30

    Representatives of US earth observations departments and agencies, other participating governments, NGOs and civil society participated in the Sixth Plenary Meeting of the Group on Earth Observations (GEO-VI), hosted by the United States in Washington, DC on November 17 and 18, 2009. The meeting was held in the Atrium Ballroom of the Ronald Reagan International Trade Center. Exhibitions of international Earth observation technology and programs were held concurrently in the same venue. A number of GEO committee meetings and side events were held in conjunction with the GEO-VI Plenary, including the GEO-IGOS Symposium on Earth observation science and applications, the GEOSS in the Americas Forum on Coastal Zones, and separate meetings of the GEO Communities of Practice on Carbon, Health, and Air Quality.

  10. Proceedings of Minnowbrook Workshops I to VI

    Science.gov (United States)

    2012-01-01

    This DVD collection includes the complete proceedings of Minnowbrook Workshops I through VI. Titles include Minnowbrook I - 1993 Workshop on End-Stage Boundary Layer Transition (NASA/CP-2007-214667, CASI ID 20070038942), Minnowbrook II - 1997 Workshop on Boundary Layer Transition in Turbomachines (NASA/CP-1998-206958, CASI ID 19980206205), Minnowbrook III - 2000 Workshop on Boundary Layer Transition and Unsteady Aspects of Turbomachinery Flow (NASA/CP-2001-210888, CASI ID 20020067662), Minnowbrook IV - 2003 Workshop on Transition and Unsteady Aspects of Turbomachinery Flows (NASA TM-2004-212913, CASI ID 20040121174), Minnowbrook V - 2006 Workshop on Unsteady Flows in Turbomachinery (NASA/CP-2006-214484, CASI ID 20070024781), and Minnowbrook VI - 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics (NACA/CP-2010-216112, CASI ID 20100018557).

  11. Mechanism for the oxidation of phenol by sulfatoferrate(VI): Comparison with various oxidants.

    Science.gov (United States)

    Peings, Vanessa; Frayret, Jérôme; Pigot, Thierry

    2015-07-01

    The oxidative action of a solid and stable potassium sulfatoferrate(VI) material on phenol was studied in aqueous solution under different stoichiometries. The performance towards phenol and the total organic carbon is compared to that of potassium permanganate and calcium hypochlorite. The total mineralization of phenol is not completely achieved by the studied chemical oxidants, and some oxidation products have been identified by gas chromatography-mass spectrometry and gas chromatography-flame ionization detector analysis. A radical reaction pathway, involving the formation of oxidation intermediates or by-products such as benzoquinone, phenoxyphenol and ring opening products, is proposed for the decomposition of phenol by ferrate(VI). Phenoxyphenol is also involved in the oxidation mechanism for permanganate whereas chlorinated phenols are produced by hypochlorite. The role of the chloride anion impurity of the potassium sulfatoferrate(VI) material has been highlighted in this study; no negative impact on the removal of phenol and its mineralization is observed compared to the use of a pure commercial ferrate(VI). The efficiency of sulfatoferrate(VI) for the oxidative removal of phenol from industrial wastewater is also confirmed.

  12. Skal vi fodre svin med humanister?

    DEFF Research Database (Denmark)

    Holm, Claus

    2005-01-01

    Også i 2015 vil mange humanistiske akademikere være arbejdsløse eller lavt lønnede. Samtidig vil antallet af læger og tandlæger, ingeniører og jurister være for lavt. Hvorfor er vi så dårlige til at planlægge uddannelser? Adjungeret professor Nils Groes, DPU, mener, uddannelsessystemets uvidenhed...

  13. Prospek pengembangan industri perkulitan pada pelita VI

    Directory of Open Access Journals (Sweden)

    D Karyadi

    1995-06-01

    Full Text Available The leather industry is one of the strong competitive industry, as it comes from renewable natural resources. Therefore, the leather industry has good prospect to develop at the Pelita VI to be the industrial products export competitive. To develop leather industry and leather products should be given closed attention and well managed, especially concerning raw material supply, quality and leather waste treatment.

  14. Novel reduction of Cr(VI) from wastewater using a naturally derived microcapsule loaded with rutin-Cr(III) complex.

    Science.gov (United States)

    Qi, Yun; Jiang, Meng; Cui, Yuan-Lu; Zhao, Lin; Liu, Shejiang

    2015-03-21

    The harmfulness of carcinogenic hexavalent chromium (Cr(VI)) is dramatically decreased when Cr(VI) is reduced to trivalent chromium (Cr(III)). Rutin, a natural flavonoid, exhibits excellent antioxidant activity by coordinating metal ions. In this study, a complex containing rutin and Cr(III) (rutin-Cr(III)) was synthesized and characterized. The rutin-Cr(III) complex was much easier to reduce than rutin. The reduction of the rutin-Cr(III) complex was highly pH-dependent, with 90% of the Cr(VI) being reduced to Cr(III) in 2h under optimal conditions. A biodegradable, sustained-release system encapsulating the rutin-Cr(III) complex in a alginate-chitosan microcapsule (rutin-Cr(III) ACMS) was also evaluated, and the reduction of Cr(VI) was assessed. This study also demonstrated that low-pH solutions increased the reduction rate of Cr(VI). The environmentally friendly microcapsules can reduce Cr(VI) for prolonged periods of time and can easily biodegrade after releasing the rutin-Cr(III) complex. Given the excellent performance of rutin-Cr(III) ACMS, the microcapsule system represents an effective system for the remediation of Cr(VI) pollution.

  15. Reactive oxygen species mediate Cr(VI)-induced carcinogenesis through PI3K/AKT-dependent activation of GSK-3β/β-catenin signaling

    Energy Technology Data Exchange (ETDEWEB)

    Son, Young-Ok; Pratheeshkumar, Poyil; Wang, Lei; Wang, Xin; Fan, Jia; Kim, Dong-Hern; Lee, Ju-Yeon; Zhang, Zhuo [Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305 (United States); Lee, Jeong-Chae [Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305 (United States); School of Dentistry and Institute of Oral Biosciences, Research Center of Bioactive Materials, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Shi, Xianglin, E-mail: xshi5@email.uky.edu [Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536-0305 (United States)

    2013-09-01

    Cr(VI) compounds are known human carcinogens that primarily target the lungs. Cr(VI) produces reactive oxygen species (ROS), but the exact effects of ROS on the signaling molecules involved in Cr(VI)-induced carcinogenesis have not been extensively studied. Chronic exposure of human bronchial epithelial cells to Cr(VI) at nanomolar concentrations (10–100 nM) for 3 months not only induced cell transformation, but also increased the potential of these cells to invade and migrate. Injection of Cr(VI)-stimulated cells into nude mice resulted in the formation of tumors. Chronic exposure to Cr(VI) increased levels of intracellular ROS and antiapoptotic proteins. Transfection with catalase or superoxide dismutase (SOD) prevented Cr(VI)-mediated increases in colony formation, cell invasion, migration, and xenograft tumors. While chronic Cr(VI) exposure led to activation of signaling cascades involving PI3K/AKT/GSK-3β/β-catenin and PI3K/AKT/mTOR, transfection with catalase or SOD markedly inhibited Cr(VI)-mediated activation of these signaling proteins. Inhibitors specific for AKT or β-catenin almost completely suppressed the Cr(VI)-mediated increase in total and active β-catenin proteins and colony formation. In particular, Cr(VI) suppressed autophagy of epithelial cells under nutrition deprivation. Furthermore, there was a marked induction of AKT, GSK-3β, β-catenin, mTOR, and carcinogenic markers in tumor tissues formed in mice after injection with Cr(VI)-stimulated cells. Collectively, our findings suggest that ROS is a key mediator of Cr(VI)-induced carcinogenesis through the activation of PI3K/AKT-dependent GSK-3β/β-catenin signaling and the promotion of cell survival mechanisms via the inhibition of apoptosis and autophagy. - Highlights: • Chronic exposure to Cr(VI) induces carcinogenic properties in BEAS-2B cells. • ROS play an important role in Cr(VI)-induced tumorigenicity of BEAS-2B cells. • PI3K/AKT/GSK-3β/β-catenin signaling involved in Cr(VI

  16. In vitro evaluation of bioremediation capacity of a commercial probiotic, Bacillus coagulans, for chromium (VI and lead (II toxicity

    Directory of Open Access Journals (Sweden)

    Pranoti Belapurkar

    2016-01-01

    Full Text Available Introduction: The bioaccumulation of heavy metals including chromium (VI (Cr (VI and lead (II (Pb (II causes fatal toxicity in humans. Some naturally occurring bacterial genera such as Bacillus and Pseudomonas help in bioremediation of these heavy metals and some of the species of Bacillus are proven probiotics. However, no study has been conducted on Bacillus coagulans, which is a proven probiotic species of genus Bacillus. Objectives: The primary objective of the present study was to assess the potential of a proven probiotic, B. coagulans, marketed as “Sporlac-DS,” to survive in the presence of Cr (VI and Pb (II and its ability to reduce its concentration in vitro. Materials and Methods: The Minimum inhibitory concentration (MIC of the organism for Cr (VI and Pb (II was determined followed by its biochemical and morphological characterization. Its antibiotic sensitivity and probiotic efficacy were assessed. Further, its bioremediation capacity was observed in vitro by determining the residual Cr (VI and Pb (II concentration after 72 h. Results: B. coagulans could tolerate up to 512 ppm concentration of Cr (VI and had an MIC of 128 ppm for Pb (II. After 72 h, the organism reduced 32 ppm Cr (VI and 64 ppm Pb (II by 93% and 89%, respectively. When B. coagulans was studied before and after growing on Cr (VI and Pb (II for 24 h, an increase was seen in sensitivity toward the tested antibiotics whereas no change was observed in morphological and biochemical characters. It also showed no change in their bile and acid tolerance, indicating that it retains its probiotic efficacy. Conclusion: The tested probiotic B. coagulans may have a potential role in bioremediation of Cr (VI and Pb (II, in vivo.

  17. Enhanced Cr(VI) reduction and As(III) oxidation in ice phase: Important role of dissolved organic matter from biochar

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Xiaoling [Department of Soil and Water Science, University of Florida, Gainesville, FL 32611 (United States); Ma, Lena Q., E-mail: lqma@ufl.edu [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210046 (China); Department of Soil and Water Science, University of Florida, Gainesville, FL 32611 (United States); Gress, Julia; Harris, Willie [Department of Soil and Water Science, University of Florida, Gainesville, FL 32611 (United States); Li, Yuncong [Soil and Water Science Department, Tropical Research and Education Center, University of Florida, Homestead, FL 33031-3314 (United States)

    2014-02-01

    Graphical abstract: - Highlights: • Biochar-derived dissolved organic matter (DOM) effectively reduced Cr(VI) and oxidized As(III). • Cr(VI) and As(III) could serve as a redox couple. • Cr(VI) and As(III) redox conversion was more effective in the ice phase than aqueous phase. • FTIR and ESR showed that biochar DOM served as both electron donor and acceptor. - Abstract: This study evaluated the impact of DOM from two biochars (sugar beet tailing and Brazilian pepper) on Cr(VI) reduction and As(III) oxidation in both ice and aqueous phases with a soil DOM as control. Increasing DOM concentration from 3 to 300 mg C L{sup −1} enhanced Cr(VI) reduction from 20% to 100% and As(III) oxidation from 6.2% to 25%; however, Cr(VI) reduction decreased from 80–86% to negligible while As(III) oxidation increased from negligible to 18–19% with increasing pH from 2 to 10. Electron spin resonance study suggested semiquinone radicals in DOM were involved in As(III) oxidation while Fourier transform infrared analysis suggested that carboxylic groups in DOM participated in both Cr(VI) reduction and As(III) oxidation. During Cr(VI) reduction, part of DOM (∼10%) was oxidized to CO{sub 2}. The enhanced conversion of Cr(VI) and As(III) in the ice phase was due to the freeze concentration effect with elevated concentrations of electron donors and electron acceptors in the grain boundary. Though DOM enhanced both Cr(VI) reduction and As(III)oxidation, Cr(VI) reduction coupled with As(III) oxidation occurred in absence of DOM. The role of DOM, Cr(VI) and/or As(III) in Cr and As transformation may provide new insights into their speciation and toxicity in cold regions.

  18. Integrated reduction/oxidation reactions and sorption processes for Cr(VI) removal from aqueous solutions using Laminaria digitata macro-algae

    OpenAIRE

    Dittert, Ingrid M.; Pina, Frederico; Souza,Selene M. A. Guelli U. de; Botelho, Cid??lia M.S.; Vilar, V??tor J.P.; Boaventura, Rui A.R.; Souza, Ant??nio Augusto U. de; Silva, Eduardo A.B. da; Brand??o, Heloisa de Lima

    2015-01-01

    The main goal of this work was the valorization of seaweed Laminaria digitata, after acid pre-treatment, for the remediation of hexavalent chromium solutions. The Cr(VI) removal efficiency by the protonated biomass was studied as a function of different parameters, such as contact time, pH, biomass and Cr(VI) concentration, and temperature. Cr(VI) removal is based on a complex mechanism that includes a reduction of Cr(VI) to Cr(III), through the oxidation of biomass at acidic medi...

  19. Solid waste removes toxic liquid waste: adsorption of chromium(VI) by iron complexed protein waste.

    Science.gov (United States)

    Fathima, Nishtar Nishad; Aravindhan, Rathinam; Rao, Jonnalagadda Raghava; Nair, Balachandran Unni

    2005-04-15

    The leather processing industry generates huge amounts of wastes, both in solid and liquid form. Fleshing from animal hides/skins is one such waste that is high in protein content. In this study, raw fleshing has been complexed with iron and is used for removal of chromium(VI). The effect of pH and the initial concentration of chromium(VI) on the removal of Cr(IV) by iron treated fleshing is presented. Iron treatment is shown to greatly improve adsorption of the fleshing for hexavalent chromium. The ultimate adsorption capacity of iron treated fleshing is 51 mg of chromium(VI) per gram of fleshing. That of untreated fleshing is 9 mg/g such that iron treatment increases the adsorption capacity of fleshing by 10-fold. The measured adsorption kinetics is well described by a pseudo-second-order kinetic model. The uptake of chromium(VI) by fleshing is best described by the Langmuir adsorption isotherm model. X-ray photoelectron spectroscopic (XPS) studies show that the iron is incorporated into the protein matrix. Shifts in XPS spectra suggest that dichromate binding occurs with iron at active adsorption sites and that iron treated fleshing removes chromium(VI) without reducing it to chromium(III).

  20. Biosorption of Cr(VI from Aqueous Solutions Using Trametes Versicolor Polyporus Fungi

    Directory of Open Access Journals (Sweden)

    M. Venkata Subbaiah

    2008-01-01

    Full Text Available Removal of chromium(VI from aqueous solution was studied using abundantly available trametes versicolor polyporus fungi as biosorbing medium under equilibrium and column flow conditions. Various sorption parameters such as contact time, effect of pH, concentration of Cr(VI and amount of biomass on the adsorption capacity of the biosorbent were studied. The equilibrium adsorption data were fitted to Freundlich and Langmuir adsorption isotherm models and the model parameters are evaluated. In addition, the data were used to predict the kinetics of adsorption. The results indicated that the adsorption of Cr(VI on fungi followed second order kinetics. The column flow adsorption data were used to predict break through curves. The fungi loaded with Cr(VI was regenerated with 0.1 M NaOH solution and the regenerated biomass was used in the subsequent adsorptiondesorption cycles. The experimental results demonstrated that the trametes versicolor polyporus fungi could be used as sorbent for immobilizing Cr(VI.

  1. Cr(VI) reduction in wastewater using a bimetallic galvanic reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lugo-Lugo, Violeta [Centro Conjunto de Investigacion en Quimica Sustentable UAEM-UNAM, Universidad Autonoma del Estado de Mexico, Facultad de Quimica. Paseo Colon interseccion Paseo Tollocan S/N. C.P. 50120, Toluca (Mexico); Barrera-Diaz, Carlos, E-mail: cbarrera@uaemex.mx [Centro Conjunto de Investigacion en Quimica Sustentable UAEM-UNAM, Universidad Autonoma del Estado de Mexico, Facultad de Quimica. Paseo Colon interseccion Paseo Tollocan S/N. C.P. 50120, Toluca (Mexico); Bilyeu, Bryan [Xavier University of Louisiana, Department of Chemistry, 1 Drexel Drive, New Orleans, LA 70125 (United States); Balderas-Hernandez, Patricia [Centro Conjunto de Investigacion en Quimica Sustentable UAEM-UNAM, Universidad Autonoma del Estado de Mexico, Facultad de Quimica. Paseo Colon interseccion Paseo Tollocan S/N. C.P. 50120, Toluca (Mexico); Urena-Nunez, Fernando [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Col. Escandon, Delegacion Miguel Hidalgo, C.P. 11801, Mexico, D.F. (Mexico); Sanchez-Mendieta, Victor [Centro Conjunto de Investigacion en Quimica Sustentable UAEM-UNAM, Universidad Autonoma del Estado de Mexico, Facultad de Quimica. Paseo Colon interseccion Paseo Tollocan S/N. C.P. 50120, Toluca (Mexico)

    2010-04-15

    The electrochemical reduction of Cr(VI)-Cr(III) in wastewater by iron and copper-iron bimetallic plates was evaluated and optimized. Iron has been used as a reducing agent, but in this work a copper-iron galvanic system in the form of bimetallic plates is applied to reducing hexavalent chromium. The optimal pH (2) and ratio of copper to iron surface areas (3.5:1) were determined in batch studies, achieving a 100% reduction in about 25 min. The Cr(VI) reduction kinetics for the bimetallic system fit a first order mechanism with a correlation of 0.9935. Thermodynamic analysis shows that the Cr(VI) reduction is possible at any pH value. However, at pH values above 3.0 for iron and 5.5 for chromium insoluble species appear, indicating that the reaction will be hindered. Continuous column studies indicate that the bimetallic copper-iron galvanic system has a reduction capacity of 9.5890 mg Cr(VI) cm{sup -2} iron, whereas iron alone only has a capacity of 0.1269 mg Cr(VI) cm{sup -2}. The bimetallic copper-iron galvanic system is much more effective in reducing hexavalent chromium than iron alone. The exhausted plates were analyzed by SEM, EDS, and XRD to determine the mechanism and the surface effects, especially surface fouling.

  2. Bioremediation of Chromium (VI from Textile Industry’s Effluent and Contaminated Soil Using Pseudomonas putida

    Directory of Open Access Journals (Sweden)

    Deepali

    2011-01-01

    Full Text Available Nine bacterial colonies were screened for the Cr(VI removal efficiency and out of these three bacterial strains Pseudomonas putida, Pseudomonas aeruginosa and Bacillus sp. were isolated from soil and used to remove Cr(VI from aqueous solution. The effect of time and concentrations on the removal rate of hexavalent chromium were studied using batch experiment. Maximum Cr (VI removal was noted 75.0% by Bacillus sp. at 10mg/l, 69.70% by Pseudomonas aeruginosa at 40mg/l and 90.88% by Pseudomonas putida at 10mg/l of synthetic solution, during 96 hours. Among these three bacteria, the maximum Cr(VI removal was reported by Pseudomonas putida on lower concentration. On the basis of highest removal rate, Pseudomonas putida was selected and used for further chromium removal from samples. It was found to be removed the highest Cr(VI by 82.92%, from effluent and 74.41% from soil during 96 hours. The present study depicts that bacteria removes chromium efficiently and this could be used for industrial waste management and other environmental contaminants.

  3. Bioreduction of U(VI) in the presence of phosphate

    Science.gov (United States)

    Boyanov, M. I.; Mishra, B.; Latta, D. E.; Rui, X.; Kwon, M.-J.; Fletcher, K. E.; Loeffler, F. E.; O'Loughlin, E. J.; Kemner, K. M.

    2012-04-01

    Phosphate/phosphoryl moieties are ubiquitous in biological and environmental systems and can potentially affect the speciation of uranium during natural attenuation or stimulated bioremediation processes. The reactivity between U(VI) and phosphate has been studied extensively, but the significant influence of phosphate groups on the formation of reduced U(IV) species has only recently been recognized. We will compare and contrast the bioreduction of dissolved and solid-phase U(VI) by Gram-positive and Gram-negative metal-reducing bacteria (Shewanella, Anaeromyxobacter, Geobacter, and Desulfitobacterium) in the presence and absence of phosphate, from the perspective of solid-phase U speciation as determined by U L-edge x-ray absorption spectroscopy (XANES and EXAFS). In all cases examined, the presence of phosphate at concentrations of P/U > 1 led to the formation of reduced, inner-sphere complexed U(IV)-phosphate species that prevented the lowest-solubility U(IV) mineral uraninite (UO2) from forming over at least several months. In the absence of phosphate, nanoparticulate uraninite or complexed non-uraninite U(IV) species were observed (depending on the system and conditions), suggesting that the interplay between the chemical conditions at the location of electron transfer to U(VI) control the U(IV) product and subsequently the stability of reduced U. The importance of non-uraninite U(IV) species will be discussed in the context of their predominance in biostimulated sediments from the Oak Ridge field site in the United States.

  4. Preparation and application of sustained release microcapsules of potassium ferrate(VI) for dinitro butyl phenol (DNBP) wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Wang Huilong, E-mail: davidwang_71@yahoo.com.cn [Department of Chemistry, Dalian University of Technology, Dalian 116023 (China); Liu Shuqin [Department of Chemistry, Dalian University of Technology, Dalian 116023 (China); Zhang Xiuyan [Dalian Fishery Technical Extension Center, Dalian 116023 (China)

    2009-09-30

    The encapsulated potassium ferrate(VI) (K{sub 2}FeO{sub 4}) samples were successfully prepared by phase separation method in organic solvents. The ethyl cellulose and paraffin were selected for the microcapsule wall materials (WM). The as prepared microcapsules were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The stability can be enhanced greatly when ferrate(VI) was encapsulated in the microcapsules with a mass ratio of Fe(VI):WM in the range of 1:1-1:3 for the same conserved time in air compared for pure K{sub 2}FeO{sub 4}. The sustained release behavior of the microcapsules with different Fe(VI):WM mass ratios in 8.0 M KOH solution was also investigated. The results indicated that the Fe(VI) release was reduced with increase of Fe(VI):WM mass ratios from 1:1 to 1:3. The release kinetics of the microcapsules is found to obey Ritger-Peppas equation. The prepared Fe(VI) microcapsules has been used for the removal of a typical alkyl dinitro phenol compound, 2-sec-butyl-4,6-dinitrophenol (DNBP), from aqueous solution. The effect of pH, microcapsule concentration and reaction time was studied thoroughly. The optimal pH for DNBP degradation was 6.5, and at this pH and a microcapsule concentration of 1.2 g/L, approximately 93% of the DNBP was degraded after 80 min. The encapsulated ferrate(VI) samples were found to be very effective in the decolorization and COD reduction of real wastewater from DNBP manufacturing. Thus, this study showed the feasible and potential use of encapsulated Fe(VI) samples in degradation of various toxic organic contaminants and industrial effluents.

  5. Synthesis and characterization of polyaniline/zeolite nanocomposite for the removal of chromium(VI from aqueous solution

    Directory of Open Access Journals (Sweden)

    Abdulsalam A. Shyaa

    2015-01-01

    Batch adsorption experiments were used to investigate the effect of various experimental parameters on the equilibrium adsorption of chromium(VI on PANI/zeolite nanocomposite. The adsorption characteristics of the composite toward Cr(VI in dilute aqueous solution were followed spectrophotometrically. The effect of contact time, size of the sorbent and the concentration of Cr(VI in solution on the metal uptake behavior of the composite were studied. It has been observed that the capacity of chromium adsorption on PANI/zeolite increases with initial metal concentration, the metal ion adsorption on surfactant is well represented by the Freundlich isotherm.

  6. Photoreduction of Cr(VI Ions in Aqueous Solutions by UV/TiO2 Photocatalytic Processes

    Directory of Open Access Journals (Sweden)

    Chih Ming Ma

    2012-01-01

    Full Text Available This study discussed the photoreduction of Cr(VI ions in aqueous solutions by UV/TiO2 photocatalytic processes under various operational factors. Experimental results showed that the removal rate of Cr(VI increased with decreasing solution pH values and with increasing dosages of organic compounds, indicating that the recombination rate of electrons and h+ can be retarded in the reaction systems by the addition of the scavenger, thus raising the reaction rate of Cr(VI. The relationship of the chemical reaction rate of Cr(VI, TiO2 dosage, and changes of Cr(VI concentration was expressed by the pseudo-first-order kinetic equation. Comparing the experimental results of two different doping metals in modified TiO2 photoreduction systems, the removal rate of Cr(VI by the Ag/TiO2 process is larger, possibly because the electron transferring ability of Ag is superior to that of Cu. However, the photoreduction rates of Cr(VI by modified UV/TiO2 processes are worse than those by a nonmodified commercial UV/TiO2 process.

  7. Papaya Seeds as A Low-Cost Sorbent for Removing Cr(VI) from The Aqueous Solution

    Science.gov (United States)

    Rahmawati, Atik; Marwoto, Putut; Karunia Z, Anita

    2016-08-01

    The presence of chromium (VI) contaminants and their toxicity in aqueous streams important environmental problems. Adsorption is one of the effective techniques that can be used for removing metal from wastewater. This research was initiated by preparing sorbent from papaya seeds and determining its functional group contents by using FT-IR. The adsorption process was carried out in a batch method. The study of adsorption aspects involved the pH, initial Cr (VI) concentration and contact time between Cr (VI) and sorbent. FT IR analysis results showed that the main functional groups are carbonyl, hydroxyl, and carboxylic. It was also found that the effective pH for Cr (VI) uptake is 2.0 and increasing contact time would increase the Cr (VI) uptake. In addition, the equilibrium was reached after 40 minutes interaction and the increase of initial chromium (VI) concentration would increase the sorbent uptake percentage. All these results indicated that papaya seed is a potential sorbent for removing Cr (VI) from aqueous solutions.

  8. STUDIES ON THE CHEMICAL NATURE OF THE SUBSTANCE INDUCING TRANSFORMATION OF PNEUMOCOCCAL TYPES : III. AN IMPROVED METHOD FOR THE ISOLATION OF THE TRANSFORMING SUBSTANCE AND ITS APPLICATION TO PNEUMOCOCCUS TYPES II, III, AND VI.

    Science.gov (United States)

    McCarty, M; Avery, O T

    1946-01-31

    1. An improved method is outlined for the isolation and purification of the pneumococcal transforming substance. This method makes use of the fact that citrate inhibits the destructive action of the enzyme, desoxyribonuclease, which is released together with the active material during lysis of the living bacterial cells. A fivefold greater yield of purified transforming agent is obtained by the present method than by the procedure previousiy described. 2. The specific transforming substance has been isolated from pneumococci of types II and VI, in addition to Type III. In each instance the biologically active material has been found to consist of desoxyribonucleic acid.

  9. Cr(VI) reduction and Cr(III) immobilization by Acinetobacter sp. HK-1 with the assistance of a novel quinone/graphene oxide composite.

    Science.gov (United States)

    Zhang, Hai-Kun; Lu, Hong; Wang, Jing; Zhou, Ji-Ti; Sui, Meng

    2014-11-04

    Cr(VI) biotreatment has attracted a substantial amount of interest due to its cost effectiveness and environmental friendliness. However, the slow Cr(VI) bioreduction rate and the formed organo-Cr(III) in solution are bottlenecks for biotechnology application. In this study, a novel strain, Acinetobacter sp. HK-1, capable of reducing Cr(VI) and immobilizing Cr(III) was isolated. Under optimal conditions, the Cr(VI) reduction rate could reach 3.82 mg h(-1) g cell(-1). To improve the Cr(VI) reduction rate, two quinone/graphene oxide composites (Q-GOs) were first prepared via a one-step covalent chemical reaction. The results showed that 2-amino-3-chloro-1,4-naphthoquinone-GO (NQ-GO) exhibited a better catalytic performance in Cr(VI) reduction compared to 2-aminoanthraquinone-GO. Specifically, in the presence of 50 mg L(-1) NQ-GO, a Cr(VI) removal rate of 190 mg h(-1) g cell(-1), which was the highest rate obtained, was achieved. The increased Cr(VI) reduction rate is mainly the result of NQ-GO significantly increasing the Cr(VI) reduction activity of cell membrane proteins containing dominant Cr(VI) reductases. X-ray photoelectron spectroscopy analysis found that Cr(VI) was reduced to insoluble Cr(III), which was immobilized by glycolipids secreted by strain HK-1. These findings indicate that the application of strain HK-1 and NQ-GO is a promising strategy for enhancing the treatment of Cr(VI)-containing wastewater.

  10. Development of Vi conjugate - a new generation of typhoid vaccine.

    Science.gov (United States)

    Szu, Shousun Chen

    2013-11-01

    Typhoid fever remains to be a serious disease burden worldwide with an estimated annual incidence about 20 million. The licensed vaccines showed moderate protections and have multiple deficiencies. Most important of all, none of the licensed typhoid vaccines demonstrated protection for children under 5 years old. These limitations impeded successful implementation of typhoid vaccination programs. To improve immunogenicity Vi was conjugated to rEPA, a recombinant exoprotein A from Pseudomonas aeruginosa. Vi-rEPA showed higher and longer lasting anti-Vi IgG in adults and children than Vi alone in high endemic areas. In school-age children and adults, the immunity persisted more than 8 years. In a double-blind, placebo-controlled and randomized efficacy trial in 2- to 5-year-old children, Vi-rEPA conferred 89% protective efficacy against typhoid fever and the protection lasted at least 4 years. When given concomitantly with infant routine vaccines, Vi-rEPA was safe, immunogenic and showed no interference with the routine vaccines. Vi conjugate vaccine was also attempted and successfully demonstrated by several other laboratories and manufactures. Using either rEPA or different carrier proteins, such as diphtheria or tetanus toxoid, recombinant diphtheria toxin (CRM197), the Vi conjugates synthesized was significantly more immunogenic than Vi alone. Recently, two Vi-tetanus toxoid conjugates were licensed in India for all ages, starts as young as 3 month old. This new generation of typhoid vaccine opens up a new era for typhoid prevention and elimination.

  11. Removal of Cr(VI) from aqueous solution by adsorption onto activated carbon.

    Science.gov (United States)

    Selvi, K; Pattabhi, S; Kadirvelu, K

    2001-10-01

    Activated carbon (AC) prepared from coconut tree sawdust was used as an adsorbent for the removal of Cr(VI) from aqueous solution. Batch mode adsorption studies were carried out by varying agitation time, initial Cr(VI) concentration, carbon concentration and pH. Langmuir and Freundlich adsorption isotherms were applied to model the adsorption data. Adsorption capacity was calculated from the Langmuir isotherm and was 3.46 mg/g at an initial pH of 3.0 for the particle size 125-250 microm. The adsorption of Cr(VI) was pH dependent and maximum removal was observed in the acidic pH range. Desorption studies were carried out using 0.01-1 M NaOH solutions.

  12. On the Energy Momentum in Bianchi Type I-III-V-VI0 Space-Time

    CERN Document Server

    Aygun, S; Tarhan, I; Aygun, Melis; Aygun, Sezgin; Tarhan, Ismail

    2006-01-01

    In this study, using the energy momentum definitions of Einstein, Moller, Bergmann-Thomson, Landau-Lifshitz and Papapetrou we compute the total energy-momentum distribution (due to matter and fields including gravitation) of the universe based on general Bianchi type I-III-V-VI(o) space-time and its transforms type I, III, V, VI(o) metrics, respectively. The energy-momentum densities are found exactly same for Einstein and Bergmann-Thomson definitions. The total energy and momentum is found to be zero for Bianchi types I and VI(o) space-times. These results are same as a previous works of Radinschi, Banerjee-Sen, Xulu and Aydogdu-Salti. Another point is that our study agree with previous works of Cooperstock-Israelit, Rosen, Johri et al.

  13. Collagen Type III and VI Turnover in Response to Long-Term Immobilization

    DEFF Research Database (Denmark)

    Sun, Shu; Henriksen, Kim; Karsdal, Morten A

    2015-01-01

    BACKGROUND: Muscle mass and function are perturbed by immobilization and remobilization. When muscle mass changes, the quality and quantity of the extracellular matrix protein, particularly the collagens, change with it. In this study, we investigated the temporal profile of three peptide...... biomarkers derived from turnover of collagen type III and type VI in a long-term immobilization and remobilization study. We also compared individual biomarker levels with Lean body Mass (LBM) and changes therein, hypothesizing that these biomarkers would be biomarkers of the remodeling processes associated...... the synthesis of collagen type III; Pro-C6, measured the synthesis of collagen type VI; and C6M measured the degradation of collagen type VI induced by MMP-2 and MMP-9 cleavage. RESULTS: Pro-C3 and Pro-C6 biomarkers are up-regulated with both immobilization and remobilization, whereas C6M is hardly affected...

  14. TREATMENT TESTS FOR EX SITU REMOVAL OF CHROMATE & NITRATE & URANIUM (VI) FROM HANFORD (100-HR-3) GROUNDWATER FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    BECK MA; DUNCAN JB

    1994-01-03

    This report describes batch and ion exchange column laboratory scale studies investigating ex situ methods to remove chromate (chromium [VI]), nitrate (NO{sub 3}{sup -}) and uranium (present as uranium [VI]) from contaminated Hanford site groundwaters. The technologies investigated include: chemical precipitation or coprecipitation to remove chromate and uranium; and anion exchange to remove chromate, uranium and nitrate. The technologies investigated were specified in the 100-HR-3 Groundwater Treatability Test Plan. The method suggested for future study is anion exchange.

  15. Clinical characteristics of patients with Rutherford category IV, compared with V and VI

    Directory of Open Access Journals (Sweden)

    Taketsugu Tsuchiya

    2015-07-01

    Full Text Available Objective: Patients categorized Rutherford category IV might have different characteristics compared with Rutherford category V and VI. Our study aims were to estimate the clinical differences between Rutherford category IV and Rutherford category V and VI, for those underwent endovascular therapy for isolated infrapopliteal disease, and also to find risk factors for endovascular therapy in Rutherford category IV. Methods: Based on the Japanese multi-center registry data, 1091 patients with 1332 limbs (Rutherford category IV: 226 patients with 315 limbs, Rutherford category V and VI: 865 patients with 1017 limbs were analyzed retrospectively. Results: Patients’ backgrounds and lesions’ characteristics had significant differences. Both freedom rate from major adverse limb event with perioperative death and amputation-free survival rate at 1 year were better in Rutherford category IV than Rutherford category V and VI (93.6% vs 78.3%, 87.7% vs 66.7% and those maintained to 3 years (p  3.0 mg/dL, chronic obstructive pulmonary disease, and coronary artery disease in Rutherford category IV. Conclusion: From the present results, Rutherford category IV should be recognized to have quite different backgrounds and better outcome from Rutherford category V and VI.

  16. A novel method for amino starch preparation and its adsorption for Cu(II) and Cr(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Dong Aiqin, E-mail: aegean.dong@gmail.com [Department of Chemistry, College of Science, Jiangxi Agricultural University, Zhimin Road, Nanchang 330045 (China); Xie Jie [Institute of Soil and Fertilizer and Environmental and Resources studies, Jiangxi Academy of Agricultural Sciences, Nanchang 330200 (China); Wang Wenmin; Yu Liping; Liu Qian [Department of Chemistry, College of Science, Jiangxi Agricultural University, Zhimin Road, Nanchang 330045 (China); Yin Yeping [Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan 430070 (China)

    2010-09-15

    A novel method was proposed to prepare amino starch by reacting ethylenediamine with previously synthesized dialdehyde starch. Different factors affecting the preparation, i.e., ethylenediamine concentration, ethylenediamine:dialdehyde starch molar ratio, pH, duration and temperature have been studied. The modified starch was characterized by IR spectroscopy, elemental analysis, X-ray diffraction and differential scanning calorimetry. The amino starch derivatives were evaluated as adsorbents. The adsorption activity for heavy metals such as Cu(II) and Cr(VI) by crosslinked amino starch was studied in terms of adsorption amount, kinetics and isotherm; and adsorbent reuse were also studied. Adsorption processes for Cu(II) and Cr(VI) on crosslinked amino starch fit a Langmuir isotherm, and adsorption for Cu(II) and Cr(VI) from aqueous solution was endothermic reactions. Crosslinked amino starch was very effective for the adsorption of Cu(II) and Cr(VI), and efficient in capacity, recycled.

  17. As(V)/Cr(VI) retention on un-amended and waste-amended soil samples: competitive experiments.

    Science.gov (United States)

    Rivas-Pérez, Ivana M; Conde-Cid, Manuel; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel; Fernández-Sanjurjo, María J; Álvarez-Rodríguez, Esperanza; Núñez-Delgado, Avelino

    2017-01-01

    Focusing on simultaneous arsenic and chromium pollution, we used batch-type experiments to study As(V)/Cr (VI) competitive sorption on soil samples, pyritic material, mussel shell, oak ash, pine bark and hemp waste, as well as on binary mixtures (50 % mussel shell and 50 % another material-oak ash, pine bark, or hemp waste), and on forest and vineyard soil samples and pyritic material amended with 48 t ha(-1) of mussel shell, oak ash, pine bark, or hemp waste. Equal As(V) and Cr(VI) concentrations (0 to 6 mmol L(-1)) were added to the individual materials, binary mixtures, and 48 t ha(-1) amended materials. The individual forest soil sample, pyritic material, and oak ash showed clearly higher As(V) sorption, whereas Cr(VI) sorption was higher on pine bark. Sorption was up to 50 % higher for As(V) than for Cr(VI) on the forest soil sample, oak ash, and pyritic material, while pine bark sorbed 95 % more Cr(VI). Regarding binary mixtures, the presence of mussel shell increased As(V) sorption on pine bark and Cr(VI) sorption on hemp waste. As regards the amendments, in the case of the forest soil sample, the amendments with oak ash and mussel shell increased As(V) sorption, while pine bark amendment increased Cr(VI) sorption; in the vineyard soil sample, the mussel shell amendment increased As(V) sorption; in the pyritic material, pine bark amendment increased Cr(VI) sorption. These results could be useful to appropriately manage the soils and individual or mixed by-products assayed when As(V) and Cr(VI) pollution occurs.

  18. Exploring Co-Authorship in 2 Henry VI

    Directory of Open Access Journals (Sweden)

    Darren Freebury-Jones

    2016-03-01

    Full Text Available The article explores the possibility extended by Hugh Craig and Arthur Kinney that 2 Henry VI is a collaborative play. Passages attributed to Peele and Shakespeare in Titus Andronicus were tested for ‘rare’ tetragrams (i.e. instances which occur less than five times in plays first performed between 1580-1600 in order to gain an insight into authorial borrowing and self-borrowing. In this respect, the article combines Martin Mueller’s work on tetragrams plus (four plus word sequences in ‘Shakespeare His Contemporaries’, with that of Ian Lancashire’s studies on authors’ working memories. The same methodology was also applied to passages attributed to Shakespeare and his co-author in Edward III. In particular, this study tests Act 3 of 2 Henry VI, which is considered Shakespeare’s primary contribution by Craig and Kinney, against the remainder of the play, in order to examine whether shared verbal parallels signify associative groupings at the forefront of Shakespeare’s mind as he composed the play, or whether these parallels indicate separate authorial cognitive processes.

  19. Ligational behavior of thiosemicarbazone, semicarbazone and thiocarbohydrazone ligands towards VO(IV), Ce(III), Th(IV) and UO 2(VI) ions: Synthesis, structural characterization and biological studies

    Science.gov (United States)

    Shebl, M.; Seleem, H. S.; El-Shetary, B. A.

    2010-01-01

    Mono- and binuclear VO(IV), Ce(III), Th(IV) and UO 2(VI) complexes of thiosemicarbazone, semicarbazone and thiocarbohydrazone ligands derived from 4,6-diacetylresorcinol were synthesized. The structures of these complexes were elucidated by elemental analyses, IR, UV-vis, ESR, 1H NMR and mass spectra as well as conductivity and magnetic susceptibility measurements and thermal analyses. The thiosemicarbazone (H 4L 1) and the semicarbazone (H 4L 2) ligands behave as dibasic pentadentate ligands in case of VO(IV) and UO 2(VI) complexes, tribasic pentadentate in case of Ce(III) complexes and monobasic pentadentate in case of Th(IV) complexes. However, the thiocarbohydrazone ligand (H 3L 3) acts as a monobasic tridentate ligand in all complexes except the VO(IV) complex in which it acts as a dibasic tridentate ligand. The antibacterial and antifungal activities were also tested against Rhizobium bacteria and Fusarium-Oxysporium fungus. The metal complexes of H 4L 1 ligand showed a higher antibacterial effect than the free ligand while the other ligands (H 4L 2 and H 3L 3) showed a higher effect than their metal complexes. The antifungal effect of all metal complexes is lower than the free ligands.

  20. 孟加拉国库巴煤矿Ⅵ煤顶板水-力耦合渗透性实验研究%Experimental Study of Coal VI Roof Hydro-mechanical Coupling Permeability in Barapukuria Coalmine, Bangladesh

    Institute of Scientific and Technical Information of China (English)

    柴蕊; 王皓

    2016-01-01

    为了探究巴库煤矿Ⅵ煤二分层开采顶板覆岩的渗透特性,选取具有代表性的裂隙型软岩(泥岩)和硬岩(中砂岩)两种试样进行了三轴应力状态下的全应力-应变过程渗透性对比试验,得出了主应力差-轴应变变化规律和渗透率-轴应变分布特征,实验结果表明:软、硬岩在主应力差-轴向应变曲线中的特征存在差异,软岩的主应力差随轴向应变呈现线性变化规律,而硬岩则表现出明显的弹性变形、裂隙扩展和裂隙贯通三段性,并基于实验数据给出了主应力差-轴向应变拟合公式;软岩因受泥化影响,在低轴向应变时渗透率随轴向应变表现为明显的波状起伏,在高轴向应变时渗透率-轴向应变曲线波动较小,而硬岩渗透率-轴向应变因受到岩石内部裂隙发育影响较大,随着水压力与渗透率呈现出正态分布趋势,而不同的水压力下渗透率变化更显著。其成果给分析和判断覆岩顶板裂隙突(涌)水理论研究提供了重要的实验依据。%Probing into permeability characteristics of roof overburden on second slice of coal VI in the Barapukuria coalmine, selected representative fractured soft rock (mudstone) and hard rock (medium-grained sandstone) two kinds of samples carried out complete stress-strain process permeability comparative test under triaxial stress state and come out principal stress difference-axial strain varia⁃tion pattern and permeability-axial strain distribution features. The result has shown that the characteristic performances in principal stress difference-axial strain curves of soft and hard rocks are different. The principal stress difference of soft rock is more obviously varied along with axial strain variation;while of hard rock has shown obvious three stages of elastic deformation, fracture extension and run-through among fractures. Based on tested data come out principal stress difference

  1. Advances in preparation of modified activated carbon and its applications in the removal of chromium (VI) from aqueous solutions

    Science.gov (United States)

    Deng, Z. L.; Liang, M. N.; Li, H. H.; Zhu, Z. J.

    2016-08-01

    The wastewater in which Cr(VI) is not fully treated has drawn environment researchers’ attention increasingly, due to its environmental pollution and harms to human health. Thus a high efficiency of modified activated carbon (MAC) to remove Cr(VI) has become one of the hot topics among environmental material research. This paper introduces the modification methods from the physical structure features and chemical properties of the activated carbon (AC) surface. At the same time, it briefly analyses the chemical characteristics of Cr(VI) in aqueous solutions, and on the basis of the aforementioned introduces the modification methods of the surface chemical characteristics of AC, such as: oxidation modification, reduction modification, loaded metal modification, and microwave modification. Combining studies on removing Cr(VI) from aqueous solutions by MAC in recent years, this paper anticipates the new trends of preparing MAC and the points in absorption research, offering some suggestions for future studies.

  2. Typhim Vi vaccine against typhoid fever: a clinical trial in Kenya.

    Science.gov (United States)

    Mirza, N B; Wamola, I A; Estambale, B A; Mbithi, E; Poillet, M

    1995-03-01

    Safety, tolerance and immunogenicity of the purified Vi polysaccharide vaccine (Typhim Vi) against typhoid fever was evaluated in primary school children aged 5-15 years. A total of 435 children were vaccinated, each with a single intramuscular injection in the left deltoid muscle. One hundred and ten children were randomly selected for blood samples on day 0 (pre vaccination) and day 30 (post vaccination). Vi antibodies studied by Radio immuno assay (RIA) on 97(88%) paired sera showed a seroconversion rate of 76.2% and seroprotection rate after vaccination was 74.2%, while 6.2% of children already had protective immunity before vaccination. The vaccine was well tolerated. Most commonly reported reactions were mild pain at site of injection (83%), and a few complained of mild swelling (4.6%), induration (1.1%), itching (1.1%) and headaches (1.4%). All reactions were of mild severity and disappeared within 24 to 48 hours.

  3. Ultrastructural changes in muscle cells of patients with collagen VI-related myopathies.

    Science.gov (United States)

    Tagliavini, Francesca; Sardone, Francesca; Squarzoni, Stefano; Maraldi, Nadir Mario; Merlini, Luciano; Faldini, Cesare; Sabatelli, Patrizia

    2013-10-01

    Collagen VI is an extracellular matrix protein expressed in several tissues including skeletal muscle. Mutations in COL6A genes cause Bethlem Myopathy (BM), Ullrich Congenital Muscular Dystrophy (UCMD) and Myosclerosis Myopathy (MM). Collagen VI deficiency causes increased opening of the mitochondrial permeability transition pore (mPTP), leading to ultrastructural and functional alterations of mitochondria, amplified by impairment of autophagy. Here we report for the first time ultrastructural studies on muscle biopsies from BM and UCMD patients, showing swollen mitochondria with hypodense matrix, disorganized cristae and paracrystalline inclusions, associated with dilated sarcoplasmic reticulum and apoptotic changes. These data were supported by scanning electron microscopy analysis on BM and UCMD cultured cells, showing alterations of the mitochondrial network. Morphometric analysis also revealed a reduced short axis and depicted swelling in about 3% of mitochondria. These data demonstrate that mitochondrial defects underlie the pathogenetic mechanism in muscle tissue of patients affected by collagen VI myopathies.

  4. Retention and redox behaviour of uranium(VI) by siderite (FeCO{sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Ithurbide, A.; Beaucaire, C. [CEA Saclay/DEN/DPC/SECR, Lab. de Mesures et Modelisation de la Migration des Radionucleides, Gif-sur-Yvette (France); Peulon, S.; Chausse, A. [CNRS-Univ. d' Evry-CEA, Lab. Analyse et Modelisation pour la Biologie et l' Environnment, UMR 8587, Evry (France); Miserque, F. [CEA Saclay/DEN/DPC/SCP, Lab. de Reactivite des Surfaces et des Interfaces, Gif-sur-Yvette (France)

    2010-07-01

    In the context of long-term nuclear waste management, understanding the migration of a major component of spent fuel, uranium namely, in the environment is of major importance. This study presents the kinetics of uranium(VI) retention and reduction in carbonate solutions by siderite, an iron carbonate present both in the near- and far-field. At pH 9, uranium(VI) is retained at the surface, reduced and then precipitated into UO{sub 2.67}. At pH 7, uranium(VI) seems, first, to be incorporated into iron precipitates at the solid/liquid interface and, subsequently, reduced by the Fe(II) contained in the thin layer. (orig.)

  5. DBC solvent extraction of U(VI) from thiocyanate medium

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The extraction behavior of uranium(VI) from thiocyanate medium with dibenzo-18-crown-6 (DBC) in nitrobenzene and the effects of alkali cations on the extraction were investigated. The results showed that the uranium (VI) can be effectively extracted in the presence of potassium cation, uranium (VI) is extracted as complex anionic species UO2(SCN)-3, and the stoichiometry of the extracted complex is KUO2(SCN)32DBC(o).

  6. Oral–Facial–Digital Syndrome type VI with self mutilations

    Directory of Open Access Journals (Sweden)

    Rabah M. Shawky

    2014-10-01

    Full Text Available We report the case of a 2.5 year old female, 2nd in order of birth of 1st cousin consanguineous marriage, with the typical features of Oral–Facial–Digital Syndrome type VI (OFDS VI including midline pseudo cleft upper lip, sublingual nodule, molar tooth sign by MRI brain, bilateral mesoaxial polydactyly (hexadactyly, and developmental delay. The patient had self mutilations which was not reported before in OFDS VI except once.

  7. Farvel til globaliseringen som vi kendte den

    DEFF Research Database (Denmark)

    Böss, Michael

    2009-01-01

    Vi er endt med en krise, som rækker langt ud over det globale monetære system, fordi den ideologiske ortodoksi, der skabte den, har ført til udflytning af millioner af arbejdspladser, tæring af nationalstaternes sammenhængskraft og overgreb på naturen. Kronikken refererer bl.a. til John Maynard K...... Keynes og en artikel af økonomen Robert Skidelsky i The American Prospect. Udgivelsesdato: 12. januar 2009...

  8. ViSC Social Competence Program.

    Science.gov (United States)

    Strohmeier, Dagmar; Hoffmann, Christine; Schiller, Eva-Maria; Stefanek, Elisabeth; Spiel, Christiane

    2012-01-01

    The ViSC Social Competence Program has been implemented in Austrian schools within the scope of a national strategy plan, Together Against Violence. The program is a primary preventive program designed for grades 5 to 8. The prevention of aggression and bullying is defined as a school development task, and the initial implementation of the program lasts one school year. The program consists of universal and specific actions that are implemented through in-school teacher training and a class project for students. The program was evaluated with a randomized intervention control group design. Data were collected from teachers and students. Results suggest that the program reduces aggression in schools.

  9. Difluoridodioxido(1,10-phenanthrolinemolybdenum(VI

    Directory of Open Access Journals (Sweden)

    Wenju Wang

    2009-09-01

    Full Text Available The title compound, [MoF2O2(C12H8N2], has non-crystallographic mirror symmetry. The MoVI atom shows a distorted octahedral environment, with the phenanthroline N atoms and the two oxide groups forming the equatorial plane and the F atoms occupying the apical positions. Weak C—H...O and C—H...F hydrogen-bonding contacts and π–π interactions [centroid–centroid distance = 3.662 (1 Å] connect the complex molecules into a three-dimensional supramolecular framework.

  10. Adsorption of chromium ion (VI by acid activated carbon

    Directory of Open Access Journals (Sweden)

    A. A. Attia

    2010-03-01

    Full Text Available The activated carbon produced from olive stones was chemically activated using sulfuric acid, (OS-S, and utilized as an adsorbent for the removal of Cr(VI from aqueous solution in the concentration range 4-50 mg/L. Adsorption experiments were carried out in a batch process and various experimental parameters such as effect of contact time, initial chromium ion concentration, carbon dosage, and pH on percentage removal have been studied. Adsorption results obtained for activated carbon (OS-S were compared with the acid-treated commercial activated carbon (CAC-S. The optimum efficiency shows that the Cr(VI uptake being attained at pH 1.5. The equilibrium adsorption data was better fitted to the Langmuir adsorption model. The results of kinetic models showed that the pseudo-first-order kinetic model was found to correlate the experimental data well. It was concluded that activated carbon produced from olive stones (OS-S has an efficient adsorption capacity compared to (CAC-S sample.

  11. Recent Advances in Treatment Approaches of Mucopolysaccharidosis VI.

    Science.gov (United States)

    Giugliani, Roberto; Carvalho, Clarissa Gutiérrez; Herber, Silvani; de Camargo Pinto, Louise Lapagesse

    2011-06-01

    Mucopolysaccharidosis VI is caused by accumulation of the glycosaminoglycan dermatan sulfate in all tissues due to decreased activity of the enzyme arylsulfatase B. Patients exhibit multisystemic signs and symptoms in a chronic and progressive manner, especially with changes in the skeleton, cardiopulmonary system, cornea, skin, liver, spleen and meninges. Patients usually have normal intelligence. In the past, treatment of mucopolysaccharidoses was limited to palliative medical care. The outcome for affected patients improved with the introduction of new technologies as hematopoietic stem cell transplantation, relegated to specific situations after enzyme replacement therapy (ERT) became available. The specific ERT for MPS VI, galsulfase (Naglazyme®, Biomarin Pharmaceutical) was approved in 2005 by FDA and in 2006 by EMEA, and three clinical studies including 56 patients have evaluated the efficacy and safety. Long-term follow up data with patients treated up to 5 years showed that ERT is well tolerated and associated with sustained improvements in the patients' clinical condition. Intrathecal ERT may be considered in situations of high neurosurgical risk but still it is experimental in humans, as is intra-articular ERT. It is possible that the full impact of this therapy will only be demonstrated when patients are identified and treated soon after birth, as it was shown that early introduction of ERT produced immune tolerance and improved enzyme effectiveness in the cat model. New insights on the pathophysiology of MPS disorders are leading to alternative therapeutic approaches, as gene therapy, inflammatory response modulators and substrate reduction therapy.

  12. Anti-S. typhi Vi IgG levels in children with and without typhoid vaccinations

    Directory of Open Access Journals (Sweden)

    Sriandayani

    2014-09-01

    Full Text Available Background Typhoid fever is endemic to Indonesia, with an annual incidence of 13/10,000 people. Vaccination has been shown to be an effective method to prevent typhoid fever. Of several vaccine types, the polysaccharide Vi vaccine is the most commonly used typhoid vaccine in developing countries. Results of previous studies remain inconclusive on the necessity of revaccination every 3 years. Objective To compare the mean serum antibody titers of anti-S. typhi Vi IgG and the proportion of children with protective antibody levels between children with and without typhoid Vi vaccination. Methods We conducted a cross-sectional study at Tuminting District, Manado from June to September 2012. Data was analyzed using independent T-test and Fisher’s test. Serum anti-S. typhi Vi IgG levels were measured by enzyme-linked immunosorbent assay (ELISA method. Results Seventy-six subjects were divided into two groups: 38 children who had received the typhoid Vi vaccination more than 3 years prior to this study and 38 children who never had typhoid vaccinations as a control group. No statistically significant difference in age and gender was found between the two groups. The mean serum anti-Vi IgG level was 0.55 ug/mL (SD 0.58; 95%CI 0.36 to 0.74 in the vaccinated group, significantly higher than that of the control group [0.31 ug/mL (SD 0.42; 95%CI 0.17 to 0.44; P=0.038]. The proportion of children with protective anti-Vi antibody level was higher in the vaccinated group (23.7% than in the control group (10.5%, however, this difference was not statistically significant (P=0.128. Conclusion The mean serum anti-S. typhi Vi IgG antibody level in children who had been vaccinated more than 3 years prior to the study is higher than in children who had never received typhoid vaccinations. Nevertheless, the mean antibody titers are generally non-protective in both groups. Also, the proportion of children with protective antibody levels is not significantly different

  13. Extraction of Fe(III) and U(VI) with 1-phenyl-3-methyl-4-acyl-pyrazolones-5 from aqueous solutions of different acids and complexing agents. Separation of Fe(III) from U(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Okafor, E.C. (Nigeria Univ., Nsukka (Nigeria). Dept. of Pure and Industrial Chemistry); Uzoukwu, B.A. (Port Harcourt Univ. (Nigeria). Dept. of Pure and Industrial Chemistry)

    1990-01-01

    Solvent extraction behaviour of Fe(III) and U(VI) in aqueous media containing various mineral acids or complexing agents, using 4-butyryl, 4-palmitoyl and 4-trichloroacetyl derivatives of 1-phenyl-3-methyl-pyrazolone-5 in xylene as extraction reagents have been studied. The possible extraction mechanism has been investigated. Solid complexes of Fe(III) and U(VI) with the chelating agents have been isolated and analysed. Separation factors of Fe(III) and U(VI) using these chelating agents are reported and methods suggested for separation of Fe(III) from U(VI) in an aqueous medium containing 0.1 M HCl or 5x10{sup -4} M EDTA. (orig.).

  14. Environmental survey of Region VI, Haltenbanken, 2009; Miljoeundersoekelse i Region VI, Haltenbanken, 2009

    Energy Technology Data Exchange (ETDEWEB)

    Holm, May-Helen; Cochrane, Sabine; Mannvik, Hans-Petter; Wasbotten, Ingar Halvorsen

    2010-07-01

    There has been an environmental investigation in Region VI Halten Bank. This report presents the results of the chemical and biological assays performed on samples from a total of 316 stations in 16 fields and 15 regional stations. A status of environmental conditions in the region is given at the end of the report. (AG)

  15. Environmental Survey in Region VI, Haltenbanken, 2009. Summary report; Miljoeundersoekelse i Region VI, Haltenbanken, 2009. Sammendragsrapport

    Energy Technology Data Exchange (ETDEWEB)

    Mannvik, Hans-Petter; Wasbotten, Ingar Halvorsen

    2010-07-01

    An environmental survey of Region VI, Haltenbanken, has been carried out. This report presents the results from the analyses carried out on samples from a total of 316 stations at 16 fields and 15 regional stations. A status of the environmental conditions in the region is given at the end of the report. (Author)

  16. Biomineralization of U(VI) phosphate promoted by microbially-mediated phytate hydrolysis in contaminated soils

    Science.gov (United States)

    Salome, Kathleen R.; Beazley, Melanie J.; Webb, Samuel M.; Sobecky, Patricia A.; Taillefert, Martial

    2017-01-01

    The bioreduction of uranium may immobilize a significant fraction of this toxic contaminant in reduced environments at circumneutral pH. In oxic and low pH environments, however, the low solubility of U(VI)-phosphate minerals also makes them good candidates for the immobilization of U(VI) in the solid phase. As inorganic phosphate is generally scarce in soils, the biomineralization of U(VI)-phosphate minerals via microbially-mediated organophosphate hydrolysis may represent the main immobilization process of uranium in these environments. In this study, contaminated sediments were incubated aerobically in two pH conditions to examine whether phytate, a naturally-occurring and abundant organophosphate in soils, could represent a potential phosphorous source to promote U(VI)-phosphate biomineralization by natural microbial communities. While phytate hydrolysis was not evident at pH 7.0, nearly complete hydrolysis was observed both with and without electron donor at pH 5.5, suggesting indigenous microorganisms express acidic phytases in these sediments. While the rate of hydrolysis of phytate generally increased in the presence of uranium, the net rate of inorganic phosphate production in solution was decreased and inositol phosphate intermediates were generated in contrast to similar incubations conducted without uranium. These findings suggest uranium stress enhanced the phytate-metabolism of the microbial community, while simultaneously inhibiting phosphatase production and/or activity by the indigenous population. Finally, phytate hydrolysis drastically decreased uranium solubility, likely due to formation of ternary sorption complexes, U(VI)-phytate precipitates, and U(VI)-phosphate minerals. Overall, the results of this study provide evidence for the ability of natural microbial communities to liberate phosphate from phytate in acidic sediments, possibly as a detoxification mechanism, and demonstrate the potential utility of phytate-promoted uranium

  17. Uranium(VI) Binding Forms in Selected Human Body Fluids: Thermodynamic Calculations versus Spectroscopic Measurements.

    Science.gov (United States)

    Osman, Alfatih A A; Geipel, Gerhard; Barkleit, Astrid; Bernhard, Gert

    2015-02-16

    Human exposure to uranium increasingly becomes a subject of interest in many scientific disciplines such as environmental medicine, toxicology, and radiation protection. Knowledge about uranium chemical binding forms(speciation) in human body fluids can be of great importance to understand not only its biokinetics but also its relevance in risk assessment and in designing decorporation therapy in the case of accidental overexposure. In this study, thermodynamic calculations of uranium speciation in relevant simulated and original body fluids were compared with spectroscopic data after ex-situ uranium addition. For the first time, experimental data on U(VI) speciation in body fluids (saliva, sweat, urine) was obtained by means of cryogenic time-resolved laser-induced fluorescence spectroscopy (cryo-TRLFS) at 153 K. By using the time dependency of fluorescence decay and the band positions of the emission spectra, various uranyl complexes were demonstrated in the studied samples. The variations of the body fluids in terms of chemical composition, pH, and ionic strength resulted in different binding forms of U(VI). The speciation of U(VI) in saliva and in urine was affected by the presence of bioorganic ligands, whereas in sweat, the distribution depends mainly on inorganic ligands. We also elucidated the role of biological buffers, i.e., phosphate (H(2)PO(4−)/HPO(4)(2−)) on U(VI) distribution, and the system Ca(2+)/UO(2)(2+)/PO(4)(3−) was discussed in detail in both saliva and urine. The theoretical speciation calculations of the main U(VI) species in the investigated body fluids were significantly consistent with the spectroscopic data. Laser fluorescence spectroscopy showed success and reliability for direct determination of U(VI) in such biological matrices with the possibility for further improvement.

  18. Modeling of Cr(VI) Bioreduction Under Fermentative and Denitrifying Conditions

    Science.gov (United States)

    Molins, S.; Steefel, C.; Yang, L.; Beller, H. R.

    2011-12-01

    The mechanisms of bioreductive immobilization of Cr(VI) were investigated by reactive transport modeling of a set of flow-through column experiments performed using natural Hanford 100H aquifer sediment. The columns were continuously eluted with 5 μM Cr(VI), 5 mM lactate as the electron donor, and selected electron acceptors (tested individually). Here we focus on the two separate experimental conditions that showed the most removal of Cr(VI) from solution: fermentation and denitrification. In each case, a network of enzymatic and abiotic reaction pathways was considered to interpret the rate of chromate reduction. The model included biomass growth and decay, and thermodynamic limitations on reaction rates, and was constrained by effluent concentrations measured by IC and ICP-MS and additional information from bacterial isolates from column effluent. Under denitrifying conditions, Cr(VI) reduction was modeled as co-metabolic with nitrate reduction based on experimental observations and previous studies on a denitrifying bacterium derived from the Hanford 100H aquifer. The reactive transport model results supported this interpretation of the reaction mechanism and were used to quantify the efficiency of the process. The models results also suggest that biomass growth likely relied on a nitrogen source other than ammonium (e.g. nitrate). Under fermentative conditions and based on cell suspension studies performed on a bacterial isolate from the columns, the model assumes that Cr(VI) reduction is carried out directly by fermentative bacteria that convert lactate into acetate and propionate. The evolution to complete lactate fermentation and Cr(VI) reduction took place over a week's time and simulations were used to determine an estimate for a lower limit of the rate of chromate reduction by calibration with the flow-through column experimental results. In spite of sulfate being added to these columns, sulfate reduction proceeded at a slow rate and was not well

  19. Vi lider af prætraumatisk stress

    DEFF Research Database (Denmark)

    Hansen, Brian Benjamin

    2009-01-01

    Vi lider af prætraumatisk stress. Vi vil nemlig nå det hele og presser konstant nye aftaler ind i vores kalender. Det eneste, der hjælper, er at ’gøre intet’ – men kan man overhovedet det? Udgivelsesdato: 30.09.09......Vi lider af prætraumatisk stress. Vi vil nemlig nå det hele og presser konstant nye aftaler ind i vores kalender. Det eneste, der hjælper, er at ’gøre intet’ – men kan man overhovedet det? Udgivelsesdato: 30.09.09...

  20. Studies on II-VI and III-V semiconductor nanostructures. Introduction of the core/shell/shell structure and development of CdSe nanocrystals in an automatized procedure; Untersuchungen an II-VI und III-V Halbleiternanostrukturen. Einfuehrung der Core/shell/shell-Struktur und Darstellung von CdSe-Nanokristallen in einem automatisierten Verfahren

    Energy Technology Data Exchange (ETDEWEB)

    Mekis, I.

    2005-11-15

    The work in this dissertation is focused on the development and characterization of fluorescent II-VI and III-V-Nanomaterials. Highly luminescent and photostable Nanocrystals with narrow size distributions were prepared. It was shown that nearly monodisperse CdSe-Nanocrystals could be prepared from Cd(Ac){sub 2} and TOPSe in a mixture of TOPO/TOP/HDA/TDPA. Nearly monodisperse CdSe/CdS-Core/shell-Nanocrystals have been prepared in a one-pot-synthesis by injection of H{sub 2}S-Gas into a freshly prepared crude solution of CdSe. The passivation of the CdSe-core with an inorganic shell of CdS resulted in the drastic improvement of the photoluminescence-efficiency of the colloidal solution. Reproducible room-temperature quantum yields reached up to a value of 85%. Photostability investigations have proved the enhanced stability of CdSe/CdS-Nanocrystals compared to CdSe-Nanocrystals under illumination with UV-Light. A novel type of luminescent semiconductor nanocrystal structure has been developed, consisting of a CdSe core and two anorganic shells. Highly fluorescent and nearly monodisperse CdSe/CdS/ZnS- and CdSe/ZnSe/ZnS-Core/shell/shell-nanocrystals have been prepared via organometallic- and acetate-precursors. The Core/she ll/shell particles reached reproducible room-temperature quantum yields up to 85%. Photostability investigations among CdSe-core, CdSe/CdS-Core/shell- and CdSe/CdS/ZnS- Core/shell/-shell-nanocrystals under illumination with UV-light have proved the highest photostability of the Core/shell/shell-particles. The photostabilities of CdSe/ZnSe/ZnS-and CdSe/ZnS-nanocrystals were compared under illumination with intense laser-beam in air. Another part of this work focused on the development of an automated synthesis procedure of CdSe-nanocrystals by constructing and implementing a flow-reactor system. The size and structure of prepared nanocrystals depended considerably on the Cd:Se-precursorratio and the flow-rate. The preparation of CdSe using Cd(Ac)2

  1. Study on multielemental speciation analysis of Cr(VI), As(III) and As(V) in water by advanced hyphenated technique HPLC/ICP-DRC-MS. Fast and reliable procedures.

    Science.gov (United States)

    Marcinkowska, Monika; Komorowicz, Izabela; Barałkiewicz, Danuta

    2015-11-01

    Analytical procedures for multielemental speciation analysis of arsenite - As(III), arsenate - As(V) and hexavalent chromium - Cr(VI) in water using high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC/ICP-DRC-MS) hyphenated technique have been developed. A dynamic reaction cell (DRC) for spectral interferences elimination has been involved in the experiment. Application of oxygen and ammonia as reaction gases in the DRC under various conditions has been verified. Optimization of the following chromatographic conditions: mobile phase composition, concentration of particular components, mobile phase pH and flow rate, injection volume and column temperature, has been conducted. Species separation has been carried out on anion-exchange chromatographic column using isocratic elution with: 22 mM (NH4)2HPO4, 25 mM NH4NO3 (for procedure A) and 22 mM (NH4)2HPO4, 65 mM NH4NO3 (for procedure B) as mobile phases. Detection limits (LD) for procedure A were 0.16 µg L(-1), 0.090 µg L(-1), 0.073 µg L(-1), and for procedure B were 0.14 µg L(-1), 0.062 µg L(-1), 0.15 µg L(-1) for As(III), As(V) and Cr(VI), respectively. Linearity was tested at two concentration ranges of: (0.5-10.0) µg L(-1) for procedure A and (5-50) µg L(-1) for procedure B, and showed correlation coefficients for each of the analytes to be above 0.999. Repeatability values obtained for spiked real water samples were in the range of (4.2-7.6)% and (2.0-2.4)% for procedure A and B respectively. Accuracy was calculated based on the analysis of spiked real water samples at three concentration levels. Obtained recoveries were from 94% to 102%.

  2. Can iron oxides remove Cr(VI) from drinking water at sub-ppb levels?

    Science.gov (United States)

    Kaprara, Efthymia; Simeonidis, Konstantinos; Samaras, Petros; Zouboulis, Anastasios; Mitrakas, Manassis

    2013-04-01

    Hexavalent chromium [Cr(VI)] has long been recognized as a potential carcinogen via inhalation, in contrast to trivalent chromium [Cr(III)] which is 100 times less toxic and also a necessary nutrient, essential to human glucidic metabolism. Nowadays there is an increasing concern that Cr(VI) is also carcinogenic by the oral route of exposure, while an increased number of publications indicate that Cr(VI) is a common natural pollutant. Hexavalent chromium formation is attributed to natural oxidation of Cr(III) in ultramafic derived soils and ophiolithic rocks. To verify this theory, drinking water samples were collected from targeted areas of Greece e.g. areas in which the geological background is predominated by ultramafic minerals and the water supply depends mainly on groundwater resources. Valuable guide for the samples collection was the geological map of Greece and emphasis was given to regions where the natural occurrence of Cr(VI) is thought to be more possible. A wide range of Cr concentrations (2-100 μg/L) were detected in the areas studied, with most of them ranging below the current limit of 50 μg/L, and the Cr(VI) concentration being more than 90% of the total. Since the Cr(VI) affects significant part of population worldwide, a debate was established concerning the enforcement of stringent regulation, which also demands the drinking water treatment processes re-evaluation in view of Cr(VI) removal at sub-ppb level. In this regard, adsorption has evolved as the front line of defense for chromium removal. The motivation of this work was to investigate the efficiency of iron oxides for the adsorption of Cr(VI) from drinking water and its removal at sub-ppb levels. The adsorbents examined included iron oxy-hydroxides and magnetite prepared using common low cost iron salts. Their effectiveness as Cr(VI) adsorbents was evaluated through the decrease of a Cr(VI) concentration of 100μg/L prepared in NSF water at pH 7. Preliminary batch experiments did not

  3. Understanding the role of clay minerals in the chromium(VI) bioremoval by Pseudomonas aeruginosa CCTCC AB93066 under growth condition: microscopic, spectroscopic and kinetic analysis.

    Science.gov (United States)

    Kang, Chunxi; Wu, Pingxiao; Li, Yuewu; Ruan, Bo; Li, Liping; Tran, Lytuong; Zhu, Nengwu; Dang, Zhi

    2015-11-01

    Laboratory batch experiments were conducted to investigate the role of clay minerals, e.g., kaolinite and vermiculite, in microbial Cr(VI) reduction by Pseudomonas aeruginosa under growth condition in glucose-amended mediums as a method for treating Cr(VI)-contaminated subsurface environment such as soil. Our results indicated that glucose could acted as an essential electron donor, and clay minerals significantly enhanced microbial Cr(VI) reduction rates by improving the consumption rate of glucose and stimulating the growth and propagation of P. aeruginosa. Cr(VI) bioreduction by both free cells and clay minerals-amended cells followed the pseudo-first-order kinetic model, with the latter one fitting better. The mass balance analyses and X-ray photoelectron spectroscopy analysis found that Cr(VI) was reduced to Cr(III) and the adsorption of total chromium on clay minerals-bacteria complex was small, implying that Cr(VI) bioremoval was not mainly due to the adsorption of Cr(VI) onto cells or clay minerals or clay minerals-cells complex but mainly due to the Cr(VI) reduction capacity of P. aeruginosa under the experimental conditions studied (e.g., pH 7). Atomic force microscopy revealed that the addition of clay minerals (e.g. vermiculite) decreased the surface roughness of Cr(VI)-laden cells and changed the cell morphology and dimension. Fourier transform infrared spectroscopy revealed that organic matters such as aliphatic species and/or proteins played an important role in the combination of cells and clay minerals. Scanning electron microscopy confirmed the attachment of cells on the surface of clay minerals, indicating that clay minerals could provide a microenvironment to protect cells from Cr(VI) toxicity and serve as growth-supporting materials. These findings manifested the underlying influence of clay minerals on microbial reduction of Cr(VI) and gave an understanding of the interaction between pollutants, the environment and the biota.

  4. Application of ferrate(VI) in the treatment of industrial wastes containing metal complexed cyanides : A green treatment

    Institute of Scientific and Technical Information of China (English)

    SEUNG-MOK Lee; DIWAKAR Tiwari

    2009-01-01

    The higher oxidation state of iron (Fe(VI)) was employed for the oxidation of cyanide (CN) and the simultaneous removal of copper or nickel in the mixed/complexed systems of CN-Cu, CN-Ni, or CN-Cu-Ni. The degradation of CN (1.00 mmol/L) and removal of Cu (0.095 mmol/L) were investigated as a function of Fe(VI) doses from 0.3-2.00 mmol/L at pH 10.0. It was found that Fe(VI) could readily oxidize CN and the reduction of Fe(VI) into Fe(III) might serve efficiently for the removal of free copper ions. The increase in Fe(VI) dose apparently favoured the CN oxidation as well Cu removal. Moreover, the pH dependence study (pH 10.0-13.0) revealed that the oxidation of CN was almost unaffected in the studied pH range (10.0-13.0), however, the maximum removal efficiency of Cu was obtained at pH 13.0. Similarly, treatment was carried out for CN-Ni system having the initial Ni concentration of 0.170 mmol/L and CN concentration of 1.00 mmol with Fe(VI) dose 2.00 mmol at various pH values (10.0-12.0). Results showed a partial oxidation of CN and partial removal of Ni occurred. It can be observed that Fe(VI) can partially degrade the CN-Ni complex in this pH range. Further, Fe(VI) was applied for the treatment of simulated industrial waste/effluent waters treatment containing CN, Cu, and Ni.

  5. Thermodynamics of the Complexation of Uranium(VI) by oxalate in aqueous solution at 10-70oC

    Energy Technology Data Exchange (ETDEWEB)

    Di Bernardo, Plinio; Zanonato, Pier Luigi; Tian, Guoxin; Tolazzi, Marilena; Rao, Linfeng

    2009-03-31

    The protonation reactions of oxalate (ox) and the complex formation of uranium(VI) with oxalate in 1.05 mol kg{sup -1} NaClO{sub 4} were studied at variable temperatures (10-70 C). Three U(VI)/ox complexes (UO{sub 2}ox{sub j}{sup (2-2j){sup +}} with j = 1, 2, 3) were identified in this temperature range. The formation constants and the molar enthalpies of complexation were determined by spectrophotometry and calorimetry. The complexation of uranium(VI) with oxalate ion is exothermic at lower temperatures (10-40 C) and becomes endothermic at higher temperatures (55-70 C). In spite of this, the free energy of complexation becomes more negative at higher temperatures due to increasingly more positive entropy of complexation that exceeds the increase of the enthalpy of complexation. The thermodynamic parameters at different temperatures, in conjunction with the literature data for other dicarboxylic acids, provide insight into the relative strength of U(VI) complexes with a series of dicarboxylic acids (oxalic, malonic and oxydiacetic) and rationalization for the highest stability of U(VI)/oxalate complexes in the series. The data reported in this study are of importance in predicting the migration of uranium(VI) in geological environments in the case of failure of the engineering barriers which protect waste repositories.

  6. Bio-reduction of Cr(VI) by exopolysaccharides (EPS) from indigenous bacterial species of Sukinda chromite mine, India.

    Science.gov (United States)

    Harish, R; Samuel, Jastin; Mishra, R; Chandrasekaran, N; Mukherjee, A

    2012-07-01

    Chrome mining activity has contributed intensively towards pollution of hexavalent chromium around Sukinda Valley, Orissa, India. In an attempt to study the specific contribution of exopolysaccharides (EPS) extracted from indigenous isolates towards Cr(VI) reduction, three chromium (VI) tolerant strains were isolated from the effluent mining sludge. Based on the tolerance towards Cr(VI) and EPS production capacity, one of them was selected for further work. The taxonomic identity of the selected strain was confirmed to be Enterobacter cloacae (showing 98% similarity in BLAST search to E. cloacae) through 16S rRNA analysis. The EPS production was observed to increase with increasing Cr(VI) concentration in the growth medium, highest being 0.078 at 100 mg/l Cr(VI). The extracted EPS from Enterobacter cloacae SUKCr1D was able to reduce 31.7% of Cr(VI) at 10 mg/l concentration, which was relevant to the prevailing natural concentrations at Sukinda mine effluent sludge. The FT-IR spectral studies confirmed the surface chemical interactions of hexavalent chromium with EPS.

  7. Preparation and testing of a Vi conjugate vaccine using pneumococcal surface protein A (PspA) from Streptococcus pneumoniae as the carrier protein.

    Science.gov (United States)

    Kothari, Neha; Genschmer, Kristopher R; Kothari, Sudeep; Kim, Jeong Ah; Briles, David E; Rhee, Dong Kwon; Carbis, Rodney

    2014-09-29

    In the current study pneumococcal surface protein A (PspA) was conjugated to Vi capsular polysaccharide from Salmonella Typhi to make available a vaccine against typhoid fever that has the potential to also provide broad protection from Streptococcus pneumoniae. High yielding production processes were developed for the purification of PspAs from families 1 and 2. The purified PspAs were conjugated to Vi with high recovery of both Vi and PspA. The processes developed especially for PspA family 2 could readily be adapted for large scale production under cGMP conditions. Previously we have shown that conjugation of diphtheria toxoid (DT) to Vi polysaccharide improves the immune response to Vi but can also enhance the response to DT. In this study it was shown that conjugation of PspA to Vi enhanced the anti-PspA response and that PspA was a suitable carrier protein as demonstrated by the characteristics of a T-cell dependent response to the Vi. We propose that a bivalent vaccine consisting of PspA from families 1 and 2 bound to Vi polysaccharide would protect against typhoid fever and has the potential to also protect against pneumococcal disease and should be considered for use in developing countries.

  8. Chromium(VI) adsorption from aqueous solution by Hevea Brasilinesis sawdust activated carbon.

    Science.gov (United States)

    Karthikeyan, T; Rajgopal, S; Miranda, Lima Rose

    2005-09-30

    Adsorption capacity of Cr(VI) onto Hevea Brasilinesis (Rubber wood) sawdust activated carbon was investigated in a batch system by considering the effects of various parameters like contact time, initial concentration, pH and temperature. Cr(VI) removal is pH dependent and found to be maximum at pH 2.0. Increases in adsorption capacity with increase in temperature indicate that the adsorption reaction is endothermic. Based on this study, the thermodynamic parameters like standard Gibb's free energy (DeltaG degrees ), standard enthalpy (DeltaH degrees ) and standard entropy (DeltaS degrees ) were evaluated. Adsorption kinetics of Cr(VI) ions onto rubber wood sawdust activated carbon were analyzed by pseudo first-order and pseudo second-order models. Pseudo second-order model was found to explain the kinetics of Cr(VI) adsorption most effectively. Intraparticle diffusion studies at different temperatures show that the mechanism of adsorption is mainly dependent on diffusion. The rate of intraparticle diffusion, film diffusion coefficient and pore diffusion coefficient at various temperatures were evaluated. The Langmuir, Freundlich and Temkin isotherm were used to describe the adsorption equilibrium studies of rubber wood sawdust activated carbon at different temperatures. Langmuir isotherm shows better fit than Freundlich and Temkin isotherm in the temperature range studied. The result shows that the rubber wood sawdust activated carbon can be efficiently used for the treatment of wastewaters containing chromium as a low cost alternative compared to commercial activated carbon and other adsorbents reported.

  9. High-field Faraday rotation in II-VI-based semimagnetic semiconductors

    NARCIS (Netherlands)

    Savchuk, AI; Fediv, [No Value; Nikitin, PI; Perrone, A; Tatzenko, OM; Platonov, VV

    1998-01-01

    The effects of d-d exchange interaction have been studied by measuring high-field Faraday rotation in II-VI-based semimagnetic semiconductors. For Cd1-xMnxTe crystals with x = 0.43 and at room temperature a saturation in magnetic field dependence of the Faraday rotation has been observed. In the cas

  10. Effects of a Multidisciplinary Rehabilitation Program on Pediatric Obesity: The CEMHaVi Program

    Science.gov (United States)

    Vanhelst, Jeremy; Mikulovic, Jacques; Fardy, Paul; Bui-Xuan, Gilles; Marchand, Frederic; Beghin, Laurent; Theunynck, Denis

    2011-01-01

    The objective of this study is to assess the effects of the unique 1-year health-wellness program of exercise and health education for obese youth on body mass index (BMI) and blood pressure. The CEMHaVi program included 74 obese children. Participants, 19 girls and 18 boys, and controls, 17 girls and 20 boys, were assigned to treatment. The…

  11. Extraction of uranium (VI) from nitric acidwith N-decanoylpyrrolidine (DPOD) in toluene

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The extraction behaviors of uranium (VI) from nitric acid by N-decanoylpyrrolidine (DPOD) in toluene has been studied at varying concentrations of nitric acid, extractant, salting-out agent LiNO3 and at different temperatures.The mechanism of extraction is discussedin the light of the results obtained.

  12. Modification of zirconium diphosphate with salicylic acid and its effect on the uranium (Vi) sorption; Modificacion del difosfato de circonio con acido salicilico y su efecto sobre la sorcion de uranio (VI)

    Energy Technology Data Exchange (ETDEWEB)

    Almazan T, M. G.; Garcia G, N. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Simoni, E., E-mail: guadalupe.almazan@inin.gob.mx [Universidad Paris Sud, Instituto de Fisica Nuclear, Georges Clemenceau No. 15, Orsay (France)

    2014-10-15

    The surface of zirconium diphosphate (ZrP{sub 2}O{sub 7}) was modified with salicylic acid and its effect was evaluated on the uranium (Vi) sorption. The modified surface of the material was analyzed with different analytical techniques among which are included the atomic force microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. This analysis allowed showing that the salicylic acid is being held on the surface of the zirconium diphosphate. The reactivity of modified zirconium diphosphate compared with uranium (Vi) was investigated using the classical method of batch sorption. The analysis of sorption isotherms shows that the salicylic acid has an important effect in the uranium (Vi) sorption. According to the study conducted, the interaction among the uranium (Vi) and the surface of zirconium diphosphate modified with the salicylic acid most likely leads to the complexes formation of binary (U(Vi)/ZrP{sub 2}O{sub 7}) and ternary (U(Vi)/salicylate/ZrP{sub 2}O{sub 7}) surface. (Author)

  13. Density functional study of magnetic exchange of dinuclear manganese complexes with the heteropoly-molyanion:[MnII2(Xn+Mo9O33)2]2(n-10)- (X=PV, AsV, SeVI)

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The magnetic exchange interactions between the dimanganese(II)-substituted complexes and the het-eropolymolyanion, [MnII2(Xn+Mo9O33)2]2(n-10)-(X = PV(I), AsV(II) and SeVI(III)), are investigated by using density functional theory combined with broken-symmetry approach (DFT-BS) method. The calculated magnetic exchange coupling constant (J) of complex II is in reasonable agreement with the responding experimental value and the negative J values indicate that antiferromagnetic exchange interactions exist in these complexes. Furthermore, the influence of the central heteroatom on the exchange cou-pling within the dimanganese core unit is studied from standpoints of geometry, spin density and fron-tier orbitals. It demonstrates that the change of the heteroatom X via PV-AsV-SeVI elongates the dis-tances of Mn1···Mn2 and shortens the distances of Ob···Ob, and reduces the effectiveness of the super-exchange pathways, consequently, decreasing the magnitude of the antiferromagnetic coupling constant, J, of these species.

  14. GeoViQua: quality-aware geospatial data discovery and evaluation

    Science.gov (United States)

    Bigagli, L.; Papeschi, F.; Mazzetti, P.; Nativi, S.

    2012-04-01

    GeoViQua (QUAlity aware VIsualization for the Global Earth Observation System of Systems) is a recently started FP7 project aiming at complementing the Global Earth Observation System of Systems (GEOSS) with rigorous data quality specifications and quality-aware capabilities, in order to improve reliability in scientific studies and policy decision-making. GeoViQua main scientific and technical objective is to enhance the GEOSS Common Infrastructure (GCI) providing the user community with innovative quality-aware search and evaluation tools, which will be integrated in the GEO-Portal, as well as made available to other end-user interfaces. To this end, GeoViQua will promote the extension of the current standard metadata for geographic information with accurate and expressive quality indicators, also contributing to the definition of a quality label (GEOLabel). GeoViQua proposed solutions will be assessed in several pilot case studies covering the whole Earth Observation chain, from remote sensing acquisition to data processing, to applications in the main GEOSS Societal Benefit Areas. This work presents the preliminary results of GeoViQua Work Package 4 "Enhanced geo-search tools" (WP4), started in January 2012. Its major anticipated technical innovations are search and evaluation tools that communicate and exploit data quality information from the GCI. In particular, GeoViQua will investigate a graphical search interface featuring a coherent and meaningful aggregation of statistics and metadata summaries (e.g. in the form of tables, charts), thus enabling end users to leverage quality constraints for data discovery and evaluation. Preparatory work on WP4 requirements indicated that users need the "best" data for their purpose, implying a high degree of subjectivity in judgment. This suggests that the GeoViQua system should exploit a combination of provider-generated metadata (objective indicators such as summary statistics), system-generated metadata (contextual

  15. The exploration of potassium ferrate(VI) as a disinfectant/coagulant in water and wastewater treatment.

    Science.gov (United States)

    Jiang, Jia-Qian; Wang, S; Panagoulopoulos, A

    2006-04-01

    This paper aims to explore potassium ferrate(VI) (K2FeO4) as an alternative water treatment chemical for both drinking water and wastewater treatment. The performance of potassium ferrate(VI) was evaluated in comparison with that of sodium hypochlorite (NaOCl) and that of NaOCl plus ferric sulphate (FS) or alum (AS). The dosages of ferrate(VI), NaOCl and FS/AS and sample pH values were varied in order to investigate the effects of these factors on the treatment performance. The study demonstrates that in drinking water treatment, ferrate(VI) can remove 10-20% more UV(254)-abs and DOC than FS for the same dose compared for natural pH range (6 and 8). The THMFP was reduced to less than 100 microg l(-1) by ferrate(VI) at a low dose. In addition to this, ferrate(VI) can achieve the disinfection targets (>6 log10 inactivation of Escherichia coliform (E. coli)) at a very low dose (6 mg l(-1) as Fe) and over wide working pH in comparison with chlorination (10 mg l(-1) as Cl2) plus coagulation (FS, 4 mg l(-1) as Fe). In wastewater treatment, ferrate(VI) can reduce 30% more COD, and kill 3log10 more bacteria compared to AS and FS at a similar or even smaller dose. Also, potassium ferrate(VI) can produce less sludge volume and remove more pollutants, which could make sludge treatment easier.

  16. Nitrification inhibition by hexavalent chromium Cr(VI)--Microbial ecology, gene expression and off-gas emissions.

    Science.gov (United States)

    Kim, Young Mo; Park, Hongkeun; Chandran, Kartik

    2016-04-01

    The goal of this study was to investigate the responses in the physiology, microbial ecology and gene expression of nitrifying bacteria to imposition of and recovery from Cr(VI) loading in a lab-scale nitrification bioreactor. Exposure to Cr(VI) in the reactor strongly inhibited nitrification performance resulting in a parallel decrease in nitrate production and ammonia consumption. Cr(VI) exposure also led to an overall decrease in total bacterial concentrations in the reactor. However, the fraction of ammonia oxidizing bacteria (AOB) decreased to a greater extent than the fraction of nitrite oxidizing bacteria (NOB). In terms of functional gene expression, a rapid decrease in the transcript concentrations of amoA gene coding for ammonia oxidation in AOB was observed in response to the Cr(VI) shock. In contrast, transcript concentrations of the nxrA gene coding for nitrite oxidation in NOB were relatively unchanged compared to Cr(VI) pre-exposure levels. Therefore, Cr(VI) exposure selectively and directly inhibited activity of AOB, which indirectly resulted in substrate (nitrite) limitation to NOB. Significantly, trends in amoA expression preceded performance trends both during imposition of and recovery from inhibition. During recovery from the Cr(VI) shock, the high ammonia concentrations in the bioreactor resulted in an irreversible shift towards AOB populations, which are expected to be more competitive in high ammonia environments. An inadvertent impact during recovery was increased emission of nitrous oxide (N2O) and nitric oxide (NO), consistent with recent findings linking AOB activity and the production of these gases. Therefore, Cr(VI) exposure elicited multiple responses on the microbial ecology, gene expression and both aqueous and gaseous nitrogenous conversion in a nitrification process. A complementary interrogation of these multiple responses facilitated an understanding of both direct and indirect inhibitory impacts on nitrification.

  17. Kandinsky's "Composition VI": Heideggerian Poetry in Noah's Ark

    Science.gov (United States)

    Hall, Joshua M.

    2012-01-01

    The author will begin his investigation of Wassily Kandinsky's painting "Composition VI" with Kandinsky's own commentary on the painting. He will then turn to the analysis of Kandinsky and the "Compositions" in John Sallis's book "Shades." Using this analysis as his point of departure, the author will consider how "Composition VI" resonates with…

  18. KENO-VI Primer: A Primer for Criticality Calculations with SCALE/KENO-VI Using GeeWiz

    Energy Technology Data Exchange (ETDEWEB)

    Bowman, Stephen M [ORNL

    2008-09-01

    The SCALE (Standardized Computer Analyses for Licensing Evaluation) computer software system developed at Oak Ridge National Laboratory is widely used and accepted around the world for criticality safety analyses. The well-known KENO-VI three-dimensional Monte Carlo criticality computer code is one of the primary criticality safety analysis tools in SCALE. The KENO-VI primer is designed to help a new user understand and use the SCALE/KENO-VI Monte Carlo code for nuclear criticality safety analyses. It assumes that the user has a college education in a technical field. There is no assumption of familiarity with Monte Carlo codes in general or with SCALE/KENO-VI in particular. The primer is designed to teach by example, with each example illustrating two or three features of SCALE/KENO-VI that are useful in criticality analyses. The primer is based on SCALE 6, which includes the Graphically Enhanced Editing Wizard (GeeWiz) Windows user interface. Each example uses GeeWiz to provide the framework for preparing input data and viewing output results. Starting with a Quickstart section, the primer gives an overview of the basic requirements for SCALE/KENO-VI input and allows the user to quickly run a simple criticality problem with SCALE/KENO-VI. The sections that follow Quickstart include a list of basic objectives at the beginning that identifies the goal of the section and the individual SCALE/KENO-VI features that are covered in detail in the sample problems in that section. Upon completion of the primer, a new user should be comfortable using GeeWiz to set up criticality problems in SCALE/KENO-VI. The primer provides a starting point for the criticality safety analyst who uses SCALE/KENO-VI. Complete descriptions are provided in the SCALE/KENO-VI manual. Although the primer is self-contained, it is intended as a companion volume to the SCALE/KENO-VI documentation. (The SCALE manual is provided on the SCALE installation DVD.) The primer provides specific examples of

  19. Impact of Vi vaccination on spatial patterns of typhoid fever in the slums of Kolkata, India.

    Science.gov (United States)

    Ali, Mohammad; Sur, Dipika; Kim, Deok Ryun; Kanungo, Suman; Bhattacharya, Sujit K; Manna, Byomkesh; Ochiai, R Leon; Clemens, John

    2011-11-08

    A mass typhoid Vi vaccination campaign was carried out among approximately 60,000 slum residents of Kolkata, India. This study evaluated the impact of the campaign on spatial patterns of typhoid fever. Eighty contiguous residential groups of households in the study area were randomized to receive either a single dose of the Vi polysaccharide vaccine or a single dose of the inactivated hepatitis A vaccine as the control agent. Persons aged two years and older were eligible to receive the vaccine. Vaccine protection against typhoid fever was monitored for two years after vaccination at both outpatient and inpatient facilities serving the study population. Geographic analytic and mapping tools were used in the analysis. Spatial randomness of the disease was observed during the pre-vaccination period, which turned into a significant pattern after vaccination. The high-risk areas for typhoid were observed in the area dominated by the control clusters, and the low-risk areas were in the area dominated by the Vi clusters. Furthermore, the control clusters surrounded by the Vi clusters were low risk for typhoid fever. The results demonstrated the ability of mass vaccination to change the spatial patterns of disease through the creation of spatial barriers to transmission of the disease. Understanding and mapping the disease risk could be useful for designing a community-based vaccination strategy to control disease.

  20. The Protective Role of Hyaluronic Acid in Cr(VI-Induced Oxidative Damage in Corneal Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Wei Wu

    2017-01-01

    Full Text Available Cr(VI exposure could produce kinds of intermediates and reactive oxygen species, both of which were related to DNA damage. Hyaluronan (HA has impressive biological functions and was reported to protect corneal epithelial cells against oxidative damage induced by ultraviolet B, benzalkonium chloride, and sodium lauryl sulfate. So the aim of our study was to investigate HA protection on human corneal epithelial (HCE cells against Cr(VI-induced toxic effects. The HCE cell lines were exposed to different concentrations of K2Cr2O7 (1.875, 3.75, 7.5, 15.0, and 30 μM or a combination of K2Cr2O7 and 0.2% HA and incubated with different times (15 min, 30 min, and 60 min. Our data showed that Cr(VI exposure could cause decreased cell viability, increased DNA damage, and ROS generation to the HCE cell lines. But incubation of HA increased HCE cell survival rates and decreased DNA damage and ROS generation induced by Cr(VI in a dose- and time-dependent manner. We report for the first time that HA can protect HCE cells against the toxicity of Cr(VI, indicating that it will be a promising therapeutic agent to corneal injuries caused by Cr(VI.

  1. The oxidative degradation of polystyrene resins on the removal of Cr(VI) from wastewater by anion exchange.

    Science.gov (United States)

    Xiao, Ke; Xu, Fuyuan; Jiang, Linhua; Dan, Zhigang; Duan, Ning

    2016-08-01

    Cr(VI) is a powerful oxidant and is capable of oxidizing most of the organic materials. Therefore, it is possible for Cr(VI) to oxidize the polymeric resins and change the sorption properties of the resins on the removal of Cr(VI) from wastewater by anion exchange. In this study, three polystyrene resins (D201, D202, and D301) with different functional groups (-N(+)(CH3)3, -N(+)(CH3)2(C2H4OH), and N(CH3)2) were assessed on oxidation stability for Cr(VI) removal from wastewater in fixed-bed column experiments. After a 10-cycle operation, due to the oxidation of the resin, the sorption capacity of D201, D202, and D301 resins decreased by 23.5, 29.3, and 17.3%, when approximately 20-34%, 31-50%, and 18-30% of Cr(VI) was reduced to Cr(III) during each cycle respectively. The results of the Fourier transform infrared spectroscopy (FT-IR) showed that both the cleavage of CN and the formation of CO bonds occurred on the polystyrene resins during the Cr(VI) removal process. The resin simulation experiments further validated the oxidation of CC and CN bonds connected with phenethyl groups. Based upon the results from column operations and the resin simulated experiments, the oxidation mechanism of the polystyrene resin was proposed.

  2. miR-3940-5p enhances homologous recombination after DSB in Cr(VI) exposed 16HBE cell.

    Science.gov (United States)

    Li, Yang; Hu, Guiping; Li, Ping; Tang, Shichuan; Zhang, Ji; Jia, Guang

    2016-02-17

    Hexavalent chromium (Cr(VI)) is a well-recognized human carcinogen, yet the molecular mechanisms by which cause human cancer are still not well understood. MicroRNAs (miRNAs), which are small non-coding RNAs, are involved in carcinogenesis and DNA damage repair. Previous occupational population study showed that hexavalent chromium (Cr(VI)) downregulated plasma miR-3940-5p level, and a low miR-3940-5p level was associated with high XRCC2 expression in lymphocytes, indicating that miR-3940-5p maybe play a protective effect in Cr(VI) induced DNA damage. Here we investigated miR-3940-5p expression and its roles in DNA repair in Cr(VI)-treated 16HBE cells. miR-3940-5p change was detected by qRT-PCR. Rad51 foci formation and double strand break (DSB) were investigated to assess homologous recombination repair (HR) capacity by Immunofluorescent assay and Neutral Comet assay. XRCC2 expression was also evaluated after miRNA oligonucleotides transfection using Western blot. Cr(VI) treatment suppressed miR-3940-5p level in 16HBE cells. miR-3904-5p mimic downregulated XRCC2 expression. As a result, the formation of Rad51-foci was inhibited and DSB repair was prolonged. The results indicate that miR-3940-5p plays a protective effect in Cr(VI) induced DNA damage.

  3. Adsorption and reduction: combined effect of polyaniline emeraldine salt for removal of Cr(VI) from aqueous medium

    Indian Academy of Sciences (India)

    PURNIMA BARUAH; DEBAJYOTI MAHANTA

    2016-06-01

    In this study, we have reported the removal of Cr(VI) ions by polyaniline (PANI) particles from aqueous medium. PANI in its emeraldine salt (ES) form can interact with Cr(VI), which is present as HCrO$^{−}_4$ in two ways. The adsorption of HCrO$^{−}_4$ ions due to the electrostatic interaction between partially positively charged PANI backbone and Cr(VI) anions causes the major portion of Cr(VI) removal and a small portion of Cr(VI) is reduced to Cr(III) by PANI (ES). The adsorption follows Langmuir adsorption isotherm and second-order kinetic model. It is observed that the removal of Cr(VI) is negligibly effected by the presence of other anions in the aqueous medium. The adsorption capacity of PANI (ES) is found to be 123 mg g$^{−1}$, which is very high compared to activated carbonbased materials. The adsorbed anions can be desorbed by converting PANI emeraldine salt (ES) to PANI emeraldinebase (EB). The EB form of PANI can be converted into ES form by treating with acid, which can be reused as adsorbent. It is important to note that the PANI (ES) is oxidized by HCrO$^{−}_4$ ions which decrease the hydrophilicity of thesurface of PANI particles. This causes the decrease in adsorption capacity of recycled PANI.

  4. Catalytic role of Cu(II) in the reduction of Cr(VI) by citric acid under an irradiation of simulated solar light.

    Science.gov (United States)

    Li, Ying; Chen, Cheng; Zhang, Jing; Lan, Yeqing

    2015-05-01

    The catalytic role of Cu(II) in the reduction of Cr(VI) by citric acid with simulated solar light was investigated. The results demonstrated that Cu(II) could significantly accelerate Cr(VI) reduction and the reaction obeyed to pseudo zero-order kinetics with respect to Cr(VI). The removal of Cr(VI) was related to the initial concentrations of Cu(II), citric acid, and the types of organic acids. The optimal removal of Cr(VI) was achieved at pH 4, and the rates of Cu(II) photocatalytic reduction of Cr(VI) by organic acids were in the order: tartaric acid (two α-OH groups, two -COOH groups)>citric acid (one α-OH group, three -COOH groups)>malic acid (one α-OH group, two -COOH groups)>lactic acid (one α-OH group, one -COOH group)≫succinic acid (two -COOH groups), suggesting that the number of α-OH was the key factor for the reaction, followed by the number of -COOH. The formation of Cu(II)-citric acid complex could generate Cu(I) and radicals through a pathway of metal-ligand-electron transfer, promoting the reduction of Cr(VI). This study is helpful to fully understanding the conversion of Cr(VI) in the existence of both organic acids and Cu(II) with solar light in aquatic environments.

  5. Asperosaponin VI promotes bone marrow stromal cell osteogenic differentiation through the PI3K/AKT signaling pathway in an osteoporosis model

    Science.gov (United States)

    Ke, Ke; Li, Qi; Yang, Xiaofeng; Xie, Zhijian; Wang, Yu; Shi, Jue; Chi, Linfeng; Xu, Weijian; Hu, Lingling; Shi, Huali

    2016-01-01

    Asperosaponin VI (ASA VI), a natural compound isolated from the well-known traditional Chinese herb Radix Dipsaci, has an important role in promoting osteoblast formation. However, its effects on osteoblasts in the context of osteoporosis is unknown. This study aimed to investigate the effects and mechanism of ASA VI action on the proliferation and osteogenic differentiation of bone marrow stromal cells isolated from the ovariectomized rats (OVX rBMSCs). The toxicity of ASA VI and its effects on the proliferation of OVX rBMSCs were measured using a CCK-8 assay. Various osteogenic differentiation markers were also analyzed, such as ALP activity, calcified nodule formation, and the expression of osteogenic genes, i.e., ALP, OCN, COL 1 and RUNX2. The results indicated that ASA VI promoted the proliferation of OVX rBMSCs and enhanced ALP activity and calcified nodule formation. In addition, while ASA VI enhanced the expression of ALP, OCN, Col 1 and RUNX2, treatment with LY294002 reduced all of these osteogenic effects and reduced the p-AKT levels induced by ASA VI. These results suggest that ASA VI promotes the osteogenic differentiation of OVX rBMSCs by acting on the phosphatidylinositol—3 kinase/AKT signaling pathway. PMID:27756897

  6. MMP Mediated Degradation of Type VI Collagen Is Highly Associated with Liver Fibrosis - Identification and Validation of a Novel Biochemical Marker Assay

    DEFF Research Database (Denmark)

    Veidal, Sanne Skovgard; Karsdal, Morten Asser; Vassiliadis, Efstathios

    2011-01-01

    Background and Aims: During fibrogenesis, in which excessive remodeling of the extracellular matrix occurs, both the quantity of type VI collagen and levels of matrix metalloproteinases, including MMP-2 and MMP-9, increase significantly. Proteolytic degradation of type VI collagen into small...... fragments, so-called neo-epitopes, may be specific biochemical marker of liver fibrosis. The aim of this study was to develop an ELISA detecting a fragment of type VI collagen generated by MMP-2 and MMP-9, and evaluate this assay in two preclinical models of liver fibrosis. Methods: Mass spectrometric...... analysis of cleaved type VI collagen revealed a large number of protease-generated neo-epitopes. A fragment unique to type VI collagen generated by MMP-2 and MMP-9 was selected for ELISA development. The CO6-MMP assay was evaluated in two rat models of liver fibrosis: bile duct ligation (BDL) and carbon...

  7. Claude Lévi-Strauss est mort…

    Directory of Open Access Journals (Sweden)

    Claude Dubar

    2009-11-01

    Full Text Available Ce mardi 3 novembre 2009 est jour de deuil dans la communauté des sciences humaines et sociales du monde entier et au-delà. Claude Lévi-Strauss vient de mourir alors qu’il allait avoir 101 ans. Il fut un des plus grands esprits du XXe siècle, à la fois anthropologue, philosophe, écrivain et humaniste. Il fait partie de ceux qui parvinrent à révolutionner la conception du temps des penseurs évolutionnistes occidentaux enfermés dans une pensée « progressiste » du temps issue de la philosophie d...

  8. Photovoltaic effects in II-VI heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Bube, R.H.

    1977-01-01

    Photovoltaic effects have been investigated in II-VI heterojunctions prepared by close-space vapor transport, vacuum evaporation, spray pyrolysis and sputtering. Solar efficiencies of about 8% have been measured for the following systems: (a) n-CdS film deposited on single crystal p-CdTe by vacuum evaporation, (b) n-ZnCdS film deposited on single crystal p-CdTe by spray pyrolysis, and (c) n-Indium-Tin Oxide film deposited on single crystal p-CdTe by sputtering in an inert atmosphere. Open-circuit voltages greater than 0.8 V have been measured in heterojunctions of type (b) and (c), as well as in CdTe p-n homojunctions produced by ion implantation.

  9. Six-fold Coordinated Carbon Dioxide VI

    Energy Technology Data Exchange (ETDEWEB)

    Iota, V; Yoo, C; Klepeis, J; Jenei, Z

    2006-03-01

    Under standard conditions, carbon dioxide (CO{sub 2}) is a simple molecular gas and an important atmospheric constituent while silicon dioxide (SiO{sub 2}) is a covalent solid, and represents one of the fundamental minerals of the planet. The remarkable dissimilarity between these two group IV oxides is diminished at higher pressures and temperatures as CO{sub 2} transforms to a series of solid phases, from simple molecular to a fully covalent extended-solid V, structurally analogous to SiO{sub 2} tridymite. Here, we present the discovery of a new extended-solid phase of carbon dioxide (CO{sub 2}): a six-fold coordinated stishovite-like phase VI, obtained by isothermal compression of associated CO{sub 2}-II above 50GPa at 530-650K. Together with the previously reported CO{sub 2}-V and a-carbonia, this new extended phase indicates a fundamental similarity between CO{sub 2}--a prototypical molecular solid, and SiO{sub 2}--one of Earth's fundamental building blocks. The phase diagram suggests a limited stability domain for molecular CO{sub 2}-I, and proposes that the conversion to extended-network solids above 40-50 GPa occurs via intermediate phases II, III, and IV. The crystal structure of phase VI suggests strong disorder along the caxis in stishovite-like P4{sub 2}/mnm, with carbon atoms manifesting an average six-fold coordination within the framework of sp{sup 3} hybridization.

  10. Aminopyridine modified Spirulina platensis biomass for chromium(VI) adsorption in aqueous solution.

    Science.gov (United States)

    Bayramoglu, Gulay; Akbulut, Aydin; Arica, M Yakup

    Chemical modification of Spirulina platensis biomass was realized by sequential treatment of algal surface with epichlorohydrin and aminopyridine. Adsorptive properties of Cr(VI) ions on native and aminopyridine modified algal biomass were investigated by varying pH, contact time, ionic strength, initial Cr(VI) concentration, and temperature. FTIR and analytical analysis indicated that carboxyl and amino groups were the major functional groups for Cr(VI) ions adsorption. The optimum adsorption was observed at pH 3.0 for native and modified algal biomasses. The adsorption capacity was found to be 79.6 and 158.7 mg g(-1), for native and modified algal biomasses, respectively. For continuous system studies, the experiments were conducted to study the effect of important design parameters such as flow rate and initial concentration of metal ions, and the maximum sorption capacity was observed at a flow rate of 50 mL h(-1), and Cr(VI) ions concentration 200 mg L(-1) with modified biomass. Experimental data fitted a pseudo-second-order equation. The regeneration performance was observed to be 89.6% and 94.3% for native and modified algal biomass, respectively.

  11. Optimizing magnetic nanoparticles for drinking water technology: The case of Cr(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Simeonidis, K., E-mail: ksime@physics.auth.gr [Department of Mechanical Engineering, School of Engineering, University of Thessaly, Volos 38334 (Greece); Kaprara, E. [Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Samaras, T.; Angelakeris, M.; Pliatsikas, N.; Vourlias, G. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Mitrakas, M. [Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Andritsos, N. [Department of Mechanical Engineering, School of Engineering, University of Thessaly, Volos 38334 (Greece)

    2015-12-01

    The potential of magnetite nanoparticles to be applied in drinking water treatment for the removal of hexavalent chromium is discussed. In this study, a method for their preparation which combines the use of low-cost iron sources (FeSO{sub 4} and Fe{sub 2}(SO{sub 4}){sub 3}) and a continuous flow mode, was developed. The produced magnetite nanoparticles with a size of around 20 nm, appeared relatively stable to passivation providing a removal capacity of 1.8 μg Cr(VI)/mg for a residual concentration of 50 μg/L when tested in natural water at pH 7. Such efficiency is explained by the reducing ability of magnetite which turns Cr(VI) to an insoluble Cr(OH){sub 3} form. The successful operation of a small-scale system consisting of a contact reactor and a magnetic separator demonstrates a way for the practical introduction and recovery of magnetite nanoparticles in water treatment technology. - Highlights: • Iron sulfates were used for the kilogram scale production of Fe{sub 3}O{sub 4} nanoparticles. • Studied particles showed a Cr(VI) removal capacity of 2 μg/mg in natural water. • Cr(VI) uptake is mostly based on its reduction and precipitation as Cr(OH){sub 3}. • A continuous flow reactor–magnetic separator operated with nanoparticles.

  12. Adsorption of Cr(VI) and Pb(II) from aqueous solution using agricultural solid waste.

    Science.gov (United States)

    Geetha, A; Sivakumar, P; Sujatha, M; Palanisamy, P N

    2009-04-01

    Areca nut shell, an agricultural solid waste by-product, has been studied for the removal of heavy metals Cr(VI) and Pb(II) from aqueous solution. Parameters, such as equilibrium time, effect of initial metal ion concentration, effect of pH on the removal, were analyzed. An initial pH of 4.0 was found most favourable for Cr(VI) removal and 5.0 for Pb(II) removal. Two theoretical isotherm models, namely Langmuir and Freundlich, were analyzed for the applicability of the experimental data. The Langmuir adsorption capacity (Q0) was calculated. The results of thermodynamic parameters suggest the exothermic nature of the adsorption. The desorption studies were carried out using dilute hydrochloric acid. Maximum desorption of 88% for Cr(VI) and 91% for Pb(II) were achieved. Areca nut shell waste, the low cost adsorbent is found to be effective in the removal of Cr(VI) and Pb(II) ions, and hence it can be applied for the removal of heavy metals from industrial wastewater.

  13. Adsorption of Cr(VI) from aqueous solutions by spent activated clay.

    Science.gov (United States)

    Weng, Chih-Huang; Sharma, Y C; Chu, Sue-Hua

    2008-06-30

    Adsorption of Cr(VI) onto spent activated clay (SAC), a waste produced from an edible oil refinery company, was investigated for its beneficial use in wastewater treatment. After pressure steam treatment, SAC was used as an adsorbent. The adsorption kinetic data were analyzed and fitted well in a pseudo-first-order equation and the rate of removal was found to speed up with decreasing pH and increasing temperature. Activation energy for the adsorption process was found to be 4.01-5.47 kcal/K mol. The Langmuir adsorption isotherm was used to fit the equilibrium data and the effect of pH, temperature and ionic strength were studied. The maximum adsorption capacities for Cr(VI) ranged from 0.743 to 1.422 mg/g for temperature between 4 and 40 degrees C under a condition of pH 2.0. The studies conducted show the process of Cr(VI) removal to be spontaneous at high temperature and endothermic in nature. From the waste utilization and environment point of view, the work carried out is important and useful. Results obtained can serve as baseline data for designing a treatment process using this low-cost adsorbent for the treatment of wastewater rich in Cr(VI).

  14. Manganese(II)-catalyzed and clay-minerals-mediated reduction of chromium(VI) by citrate.

    Science.gov (United States)

    Sarkar, Binoy; Naidu, Ravi; Krishnamurti, Gummuluru S R; Megharaj, Mallavarapu

    2013-01-01

    Unlike lower valent iron (Fe), the potential role of lower valent manganese (Mn) in the reduction of hexavalent chromium (Cr(VI)) in soil is poorly documented. In this study, we report that citrate along with Mn(II) and clay minerals (montmorillonite and kaolinite) reduce Cr(VI) both in aqueous phase and in the presence of dissolved organic carbon (SDOC) extracted from a forest soil. The reduction was favorable at acidic pH (up to pH 5) and followed the pseudo-first-order kinetic model. The citrate (10 mM) + Mn(II) (182.02 μM) + clay minerals (3% w/v) system in SDOC accounted for complete reduction of Cr(VI) (192.32 μM) in about 72 h at pH 4.9. In this system, citrate was the reductant, Mn(II) was a catalyst, and the clay minerals acted as an accelerator for both the reductant and catalyst. The clay minerals also serve as a sink for Cr(III). This study reveals the underlying mechanism of the Mn(II)-induced reduction of Cr(VI) by organic ligand in the presence of clay minerals under certain environmental conditions.

  15. Use of iron oxide magnetic nanosorbents for Cr (VI removal from aqueous solutions: A review

    Directory of Open Access Journals (Sweden)

    Nirmala Ilankoon

    2014-10-01

    Full Text Available This review paper focuses on the use of iron oxide nanosorbents for the removal of hexavalent Chromium [Cr(VI], from aqueous media. Cr(VI is a well-known toxic heavy metal, which can cause severe damages to the human health even with the presence of trace levels. Chromium continuously enters into water streams from different sources. Several methods are available for Cr(VI removal and some of them are well established in industrial scale whilst some are still in laboratory scale. Reduction followed by chemical precipitation, adsorption, electro-kinetic remediation, membrane separation processes and bioremediation are some of the removal techniques. Each method is associated with both advantages and disadvantages. Currently, the use of nanosorbents for the aqueous chromium removal is popular among researchers and iron oxide nanoparticles are the most frequently used nanosorbents. This review paper summarizes the performance of different iron oxide nanosorbents studied on the last decade. The direct comparison of these results is difficult due to different experimental conditions used in each study. Adsorption isotherms and adsorption kinetics models are also discussed in this review paper. The effect of solution pH, temperature, initial Cr(VI concentration, adsorbent dosage and other coexisting ions are also briefly discussed. From the results it is evident that, more attention needs to be paid on the industrial application of the technologies which were successful in the laboratory scale.

  16. AFS-2 FLOWSHEET MODIFICATIONS TO ADDRESS THE INGROWTH OF PU(VI) DURING METAL DISSOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Crapse, K.; Rudisill, T.; O' Rourke, P.; Kyser, E.

    2014-07-02

    In support of the Alternate Feed Stock Two (AFS-2) PuO{sub 2} production campaign, Savannah River National Laboratory (SRNL) conducted a series of experiments concluding that dissolving Pu metal at 95°C using a 6–10 M HNO{sub 3} solution containing 0.05–0.2 M KF and 0–2 g/L B could reduce the oxidation of Pu(IV) to Pu(VI) as compared to dissolving Pu metal under the same conditions but at or near the boiling temperature. This flowsheet was demonstrated by conducting Pu metal dissolutions at 95°C to ensure that PuO{sub 2} solids were not formed during the dissolution. These dissolution parameters can be used for dissolving both Aqueous Polishing (AP) and MOX Process (MP) specification materials. Preceding the studies reported herein, two batches of Pu metal were dissolved in the H-Canyon 6.1D dissolver to prepare feed solution for the AFS-2 PuO{sub 2} production campaign. While in storage, UV-visible spectra obtained from an at-line spectrophotometer indicated the presence of Pu(VI). Analysis of the solutions also showed the presence of Fe, Ni, and Cr. Oxidation of Pu(IV) produced during metal dissolution to Pu(VI) is a concern for anion exchange purification. Anion exchange requires Pu in the +4 oxidation state for formation of the anionic plutonium(IV) hexanitrato complex which absorbs onto the resin. The presence of Pu(VI) in the anion feed solution would require a valence adjustment step to prevent losses. In addition, the presence of Cr(VI) would result in absorption of chromate ion onto the resin and could limit the purification of Pu from Cr which may challenge the purity specification of the final PuO{sub 2} product. Initial experiments were performed to quantify the rate of oxidation of Pu(IV) to Pu(VI) (presumed to be facilitated by Cr(VI)) as functions of the HNO{sub 3} concentration and temperature in simulated dissolution solutions containing Cr, Fe, and Ni. In these simulated Pu dissolutions studies, lowering the temperature from near boiling

  17. Antimicrobial, spectral, magnetic and thermal studies of Cu(II), Ni(II), Co(II), UO(2)(VI) and Fe(III) complexes of the Schiff base derived from oxalylhydrazide.

    Science.gov (United States)

    Melha, Khlood Abou

    2008-04-01

    The Schiff base ligand, oxalyl [( 2 - hydroxybenzylidene) hydrazone] [corrected].H(2)L, and its Cu(II), Ni(II), Co(II), UO(2)(VI) and Fe(III) complexes were prepared and tested as antibacterial agents. The Schiff base acts as a dibasic tetra- or hexadentate ligand with metal cations in molar ratio 1:1 or 2:1 (M:L) to yield either mono- or binuclear complexes, respectively. The ligand and its metal complexes were characterized by elemental analyses, IR, (1)H NMR, Mass, and UV-Visible spectra and the magnetic moments and electrical conductance of the complexes were also determined. For binuclear complexes, the magnetic moments are quite low compared to the calculated value for two metal ions complexes and this shows antiferromagnetic interactions between the two adjacent metal ions. The ligand and its metal complexes were tested against a Gram + ve bacteria (Staphylococcus aureus), a Gram -ve bacteria (Escherichia coli), and a fungi (Candida albicans). The tested compounds exhibited high antibacterial activities.

  18. Tunable thermoelectricity in monolayers of MoS2 and other group-VI dichalcogenides 2 and other group-VI dichalcogenides

    KAUST Repository

    Tahir, M

    2014-10-31

    We study the thermoelectric properties of monolayers of MoS2 and other group-VI dichalcogenides under circularly polarized off-resonant light. Analytical expressions are derived for the Berry phase mediated magnetic moment, orbital magnetization, as well as thermal and Nernst conductivities. Tuning of the band gap by off-resonant light enhances the spin splitting in both the valence and conduction bands and, thus, leads to a dramatic improvement of the spin and valley thermoelectric properties.

  19. First-principles investigation of negative thermal expansion in II-VI semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lei [International Laboratory for Quantum Functional Materials of Henan, Zhengzhou University, Zhengzhou 450001 (China); Yuan, Peng-Fei; Wang, Fei; Sun, Qiang [International Laboratory for Quantum Functional Materials of Henan, Zhengzhou University, Zhengzhou 450001 (China); Center for Clean Energy and Quantum Structures, and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450052 (China); Guo, Zheng-Xiao [Deparment of Chemistry, University College London, London WCIHOAJ (United Kingdom); Liang, Er-Jun, E-mail: ejliang@zzu.edu.cn [International Laboratory for Quantum Functional Materials of Henan, Zhengzhou University, Zhengzhou 450001 (China); Center for Clean Energy and Quantum Structures, and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450052 (China); Jia, Yu, E-mail: jiayu@zzu.edu.cn [International Laboratory for Quantum Functional Materials of Henan, Zhengzhou University, Zhengzhou 450001 (China); Center for Clean Energy and Quantum Structures, and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450052 (China)

    2014-11-14

    Within the framework of first-principles, all II-VI semiconductors with cubic zinc blende structure have negative thermal expansion (NTE) behavior at low temperatures. Negative mode Grüneisen parameters are found for two transverse acoustic (TA) branches near the Brillouin-zone boundaries. Through the analysis of vibrational modes, it shows that the librational mode which brings about the bond tension effect by atomic motions perpendicular to the bonds can contribute to the NTE. Related thermodynamic properties of II-VI semiconductors have also been studied. It is demonstrated that with increased ionic radius and atomic mass, the variety of electronegativity can cause more covalent character in bonding nature, weaker interatomic force constants and lower frequencies in lattice vibrations. Thus, despite the same vibrational modes, II-VI semiconductors can present different NTE behavior and thermodynamic properties. - Highlights: • The NTE properties of II-VI semiconductors are investigated by first-principles calculation. • Negative mode Grüneisen parameters are found for two TA branches. • The librational mode can contribute to the NTE behavior. • Various ionic radius and electronegativity can cause different NTE behavior and thermodynamic properties.

  20. Simultaneous desulfurization and denitrification from flue gas by Ferrate(VI).

    Science.gov (United States)

    Zhao, Yi; Han, Yinghui; Ma, Tianzhong; Guo, Tianxiang

    2011-05-01

    An innovative semidry process has been developed to simultaneously remove NO and SO₂ from flue gas. According to the conditions of the flue gas circulating fluidized bed (CFB) system, ferrate(VI) absorbent was prepared and added to humidified water, and the effects of the various influencing factors, such as ferrate(VI) concentration, humidified water pH, inlet flue gas temperature, residence time, molar ratio of Ca/(S+N), and concentrations of SO₂ and NO on removal efficiencies of SO₂ and NO were studied experimentally. Removal efficiencies of 96.1% for SO₂ and 67.2% for NO were obtained, respectively, under the optimal experimental conditions, in which the concentration of ferrate(VI) was 0.03 M, the humidified water pH was 9.32, the inlet flue gas temperature was 130 °C, the residence time was 2.2 s, and the molar ratio of Ca/(S+N) was 1.2. In addition, the reaction mechanism of simultaneous desulfurization and denitrification using ferrate(VI) was proposed.

  1. Preparation of activated carbon from corn cob and its adsorption behavior on Cr(VI) removal.

    Science.gov (United States)

    Tang, Shuxiong; Chen, Yao; Xie, Ruzhen; Jiang, Wenju; Jiang, Yanxin

    2016-01-01

    Operation experiments were conducted to optimize the preparation of activated carbons from corn cob. The Cr(VI) adsorption capacity of the produced activated carbons was also evaluated. The impact of the adsorbent dosage, contact time, initial solution pH and temperature was studied. The results showed that the produced corn cob activated carbon had a good Cr(VI) adsorptive capacity; the theoretical maximum adsorption was 34.48 mg g(-1) at 298 K. The Brunauer-Emmett-Teller and iodine adsorption value of the produced activated carbon could be 924.9 m(2) g(-1) and 1,188 mg g(-1), respectively. Under the initial Cr(VI) concentration of 10 mg L(-1) and the original solution pH of 5.8, an adsorption equilibrium was reached after 4 h, and Cr(VI) removal rate was from 78.9 to 100% with an adsorbent's dosage increased from 0.5 to 0.7 g L(-1). The kinetics and equilibrium data agreed well with the pseudo-second-order kinetics model and the Langmuir isotherm model. The equilibrium adsorption capacity improved with the increment of the temperature.

  2. Determination of thermodynamic parameters of Cr(VI) adsorption from aqueous solution onto Agave lechuguilla biomass

    Energy Technology Data Exchange (ETDEWEB)

    Romero-Gonzalez, J. [Environmental Science and Engineering, University of Texas at El Paso, El Paso, TX 79968 (United States); Peralta-Videa, J.R. [Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968 (United States); Rodriguez, E. [Environmental Science and Engineering, University of Texas at El Paso, El Paso, TX 79968 (United States); Ramirez, S.L. [Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968 (United States); Gardea-Torresdey, J.L. [Environmental Science and Engineering, University of Texas at El Paso, El Paso, TX 79968 (United States) and Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968 (United States)]. E-mail: jgardea@utep.edu

    2005-04-15

    The temperature dependence of the Cr(VI) bioadsorption and its possible reduction to Cr(III) by Agave lechuguilla biomass were studied. The experimental data obtained in batch experiments at different temperatures were fitted to the Langmuir and Freundlich isotherms to obtain the characteristic parameters of each model. The adsorption equilibrium data fitted well with the Freundlich model. The average model parameters calculated from Freundlich's isotherms (adsorption capacity K{sub F} = 4 . 10{sup -2} mol . g{sup -1} and an average adsorption intensity value n = 13.07) showed that A. lechuguilla can be considered as an effective biomaterial for Cr(VI) removal from aqueous solution. Thermodynamic parameters ({delta}G{sup .}, {delta}H{sup .}, and {delta}S{sup .}) for Cr(VI) adsorption determined in the temperature range from (283 to 313) K suggest that a portion of Cr(VI) may be bound to functional groups on the surface of the adsorbent and then reduced to Cr(III). Additionally, the parameters of the Dubinin-Radushkevick equation indicated that the sorption of chromium species onto lechuguilla biomass mainly proceeds through binding surface functional groups.

  3. Mitochondrial dysfunction and defective autophagy in the pathogenesis of collagen VI muscular dystrophies.

    Science.gov (United States)

    Bernardi, Paolo; Bonaldo, Paolo

    2013-05-01

    Ullrich Congenital Muscular Dystrophy (UCMD), Bethlem Myopathy (BM), and Congenital Myosclerosis are diseases caused by mutations in the genes encoding the extracellular matrix protein collagen VI. A dystrophic mouse model, where collagen VI synthesis was prevented by targeted inactivation of the Col6a1 gene, allowed the investigation of pathogenesis, which revealed the existence of a Ca(2+)-mediated dysfunction of mitochondria and sarcoplasmic reticulum, and of defective autophagy. Key events are dysregulation of the mitochondrial permeability transition pore, an inner membrane high-conductance channel that for prolonged open times causes mitochondrial dysfunction, and inadequate removal of defective mitochondria, which amplifies the damage. Consistently, the Col6a1(-/-) myopathic mice could be cured through inhibition of cyclophilin D, a matrix protein that sensitizes the pore to opening, and through stimulation of autophagy. Similar defects contribute to disease pathogenesis in patients irrespective of the genetic lesion causing the collagen VI defect. These studies indicate that permeability transition pore opening and defective autophagy represent key elements for skeletal muscle fiber death, and provide a rationale for the use of cyclosporin A and its nonimmunosuppressive derivatives in patients affected by collagen VI myopathies, a strategy that holds great promise for treatment.

  4. Chitosan/mangiferin particles for Cr(VI) reduction and removal.

    Science.gov (United States)

    Sampaio, Caroline de G; Frota, Lucas S; Magalhães, Herbert S; Dutra, Lilian M U; Queiroz, Danilo C; Araújo, Rinaldo S; Becker, Helena; de Souza, José R R; Ricardo, Nágila M P S; Trevisan, Maria T S

    2015-07-01

    In this work, chitosan/mangiferin particles (CMP) were prepared by spray-drying technique and characterized by SEM, DLS, FTIR, HPLC-UV and adsorption studies to investigate a possible application as a preventive material in cases of human and animal contamination with Cr(VI). CMP presented sizes ranging from nano to micrometers. Chitosan and mangiferin (MA) presence in the powder was confirmed by FTIR and MA quantification (136 μg/mg) was performed using a calibration curve prepared by HPLC-UV. Adsorption capacity of Cr(VI) onto CMP was compared with chitosan and investigated in a batch system by considering the effects of various parameters like contact time, initial concentration of adsorbent and pH. Cr(VI) removal is pH dependent and it was found to be maximum at pH 5.0. The results showed that CMP has a potential application as a preventive material in cases of human or animal contamination with Cr(VI).

  5. Simultaneous microbial reduction of vanadium (V) and chromium (VI) by Shewanella loihica PV-4.

    Science.gov (United States)

    Wang, Guangyu; Zhang, Baogang; Li, Shuang; Yang, Meng; Yin, Changcheng

    2017-03-01

    Toxic vanadium (V) and chromium (VI) often co-exist in wastewater from vanadium ore smelting and their reductions by bacterial strain Shewanella loihica PV-4 is realized simultaneously. After 27-d operation, 71.3% of V(V) and 91.2% of Cr(VI) were removed respectively, with citrate as organic carbon source. Enhancement of Cr(VI) bioreduction was observed with the suppressed V(V) reduction. V(IV) and Cr(III), the main reduction products, precipitated inside the organisms and attached on cell surfaces. Both membrane components containing cytochrome c and cytoplasmic fractions containing soluble proteins as well as NADH may contribute to these microbial reductions. Most Cr(VI) were reduced extracellularly and V(V) tended to be reduced through intracellular process, as revealed by mapping the microbial surface and a line scan across the cell, performed by scanning transmission electron microscopy. This study provides an efficient alternative for controlling combined pollution caused by these two metals based on microbial technology.

  6. Developmental sex differences in nicotinic currents of prefrontal layer VI neurons in mice and rats.

    Directory of Open Access Journals (Sweden)

    Nyresa C Alves

    Full Text Available BACKGROUND: There is a large sex difference in the prevalence of attention deficit disorder; yet, relatively little is known about sex differences in the development of prefrontal attention circuitry. In male rats, nicotinic acetylcholine receptors excite corticothalamic neurons in layer VI, which are thought to play an important role in attention by gating the sensitivity of thalamic neurons to incoming stimuli. These nicotinic currents in male rats are significantly larger during the first postnatal month when prefrontal circuitry is maturing. The present study was undertaken to investigate whether there are sex differences in the nicotinic currents in prefrontal layer VI neurons during development. METHODOLOGY/PRINCIPAL FINDINGS: Using whole cell recording in prefrontal brain slice, we examined the inward currents elicited by nicotinic stimulation in male and female rats and two strains of mice. We found a prominent sex difference in the currents during the first postnatal month when males had significantly greater nicotinic currents in layer VI neurons compared to females. These differences were apparent with three agonists: acetylcholine, carbachol, and nicotine. Furthermore, the developmental sex difference in nicotinic currents occurred despite male and female rodents displaying a similar pattern and proportion of layer VI neurons possessing a key nicotinic receptor subunit. CONCLUSIONS/SIGNIFICANCE: This is the first illustration at a cellular level that prefrontal attention circuitry is differently affected by nicotinic receptor stimulation in males and females during development. This transient sex difference may help to define the cellular and circuit mechanisms that underlie vulnerability to attention deficit disorder.

  7. Solid phase extraction of uranium(VI) onto benzoylthiourea-anchored activated carbon.

    Science.gov (United States)

    Zhao, Yongsheng; Liu, Chunxia; Feng, Miao; Chen, Zhen; Li, Shuqiong; Tian, Gan; Wang, Li; Huang, Jingbo; Li, Shoujian

    2010-04-15

    A new solid phase extractant selective for uranium(VI) based on benzoylthiourea anchored to activated carbon was developed via hydroxylation, amidation and reaction with benzoyl isothiocyanate in sequence. Fourier transform infrared spectroscopy and total element analysis proved that benzoylthiourea had been successfully grafted to the surface of the activated carbon, with a loading capacity of 1.2 mmol benzoylthiourea per gram of activated carbon. The parameters that affect the uranium(VI) sorption, such as contact time, solution pH, initial uranium(VI) concentration, adsorbent dose and temperature, have been investigated. Results have been analyzed by Langmuir and Freundlich isotherm; the former was more suitable to describe the sorption process. The maximum sorption capacity (82 mg/g) for uranium(VI) was obtained at experimental conditions. The rate constant for the uranium sorption by the as-synthesized extractant was 0.441 min(-1) from the first order rate equation. Thermodynamic parameters (DeltaH(0)=-46.2 kJ/mol; DeltaS(0)=-98.0 J/mol K; DeltaG(0)=-17.5 kJ/mol) showed the adsorption of an exothermic process and spontaneous nature, respectively. Additional studies indicated that the benzoylthiourea-anchored activated carbon (BT-AC) selectively sorbed uranyl ions in the presence of competing ions, Na(+), Co(2+), Sr(2+), Cs(+) and La(3+).

  8. Cr(VI) removal from aqueous solution by thermophilic denitrifying bacterium Chelatococcus daeguensis TAD1 in the presence of single and multiple heavy metals.

    Science.gov (United States)

    Li, Han; Huang, Shaobin; Zhang, Yongqing

    2016-09-01

    Cr(VI) pollution is increasing continuously as a result of ongoing industrialization. In this study, we investigated the thermophilic denitrifying bacterium Chelatococcus daeguensis TAD1, isolated from the biofilm of a biotrickling filter used in nitrogen oxides (NOX) removal, with respect to its ability to remove Cr(VI) from an aqueous solution. TAD1 was capable of reducing Cr(VI) from an initial concentration of 10 mg/L to non-detectable levels over a pH range of 7-9 and at a temperature range of 30-50°C. TAD1 simultaneously removed both Cr(VI) and NO3 (-)-N at 50°C, when the pH was 7 and the initial Cr(VI) concentration was 15 mg/L. The reduction of Cr(VI) to Cr(III) correlated with the growth metabolic activity of TAD1. The presence of other heavy metals (Cu, Zn, and Ni) inhibited the ability of TAD1 to remove Cr(VI). The metals each individually inhibited Cr(VI) removal, and the extent of inhibition increased in a cooperative manner in the presence of a combination of the metals. The addition of biodegradable cellulose acetate microspheres (an adsorption material) weakened the toxicity of the heavy metals; in their presence, the Cr(VI) removal efficiency returned to a high level. The feasibility and applicability of simultaneous nitrate removal and Cr(VI) reduction by strain TAD1 is promising, and may be an effective biological method for the clean-up of wastewater.

  9. U(VI) reduction by diverse outer surface c-type cytochromes of Geobacter sulfurreducens.

    Science.gov (United States)

    Orellana, Roberto; Leavitt, Janet J; Comolli, Luis R; Csencsits, Roseann; Janot, Noemie; Flanagan, Kelly A; Gray, Arianna S; Leang, Ching; Izallalen, Mounir; Mester, Tünde; Lovley, Derek R

    2013-10-01

    Early studies with Geobacter sulfurreducens suggested that outer-surface c-type cytochromes might play a role in U(VI) reduction, but it has recently been suggested that there is substantial U(VI) reduction at the surface of the electrically conductive pili known as microbial nanowires. This phenomenon was further investigated. A strain of G. sulfurreducens, known as Aro-5, which produces pili with substantially reduced conductivity reduced U(VI) nearly as well as the wild type, as did a strain in which the gene for PilA, the structural pilin protein, was deleted. In order to reduce rates of U(VI) reduction to levels less than 20% of the wild-type rates, it was necessary to delete the genes for the five most abundant outer surface c-type cytochromes of G. sulfurreducens. X-ray absorption near-edge structure spectroscopy demonstrated that whereas 83% ± 10% of the uranium associated with wild-type cells correspond to U(IV) after 4 h of incubation, with the quintuple mutant, 89% ± 10% of uranium was U(VI). Transmission electron microscopy and X-ray energy dispersion spectroscopy revealed that wild-type cells did not precipitate uranium along pili as previously reported, but U(IV) was precipitated at the outer cell surface. These findings are consistent with those of previous studies, which have suggested that G. sulfurreducens requires outer-surface c-type cytochromes but not pili for the reduction of soluble extracellular electron acceptors.

  10. Dissolution studies of natural analogues spent fuel and U(VI)-Silicon phases of and oxidative alteration process; Estudios de disolucion de analogos naturales de combustible nuclear irradiado y de fases de U(VI)-Silicio representativas de un proceso de alteracion oxidativa

    Energy Technology Data Exchange (ETDEWEB)

    Perez Morales, I.

    2000-07-01

    In order to understand the long-term behavior of the nuclear spent fuel in geological repository conditions, we have performed dissolution studies with natural analogues to UO{sub 2} as well as with solid phases representatives of the oxidative alteration pathway of uranium dioxide, as observed in both natural environment and laboratory studies. In all cases, we have studied the influence of the bicarbonate concentration in the dissolution process, as a first approximation to the groundwater composition of a granitic environment, where carbonate is one of the most important complexing agents. As a natural analogue to the nuclear spent fuel some uraninite samples from the Oklo are deposit in Gabon, where chain fission reactions took place 2000 millions years ago, as well as a pitchblende sample from the mine Fe ore deposit, in Salamanca (spain) have been studied. The studies have been performed at 25 and 60 degree centigree and 60 degree centigree, and they have focussed on the determination of both the thermodynamic and the kinetic properties of the different samples studied, using batch and continuous experimental methodologies, respectively. (Author)

  11. Cr(VI) adsorption from electroplating plating wastewater by chemically modified coir pith.

    Science.gov (United States)

    Suksabye, Parinda; Thiravetyan, Paitip

    2012-07-15

    Coir pith samples were chemically modified by grafting with acrylic acid for the removal of Cr(VI) from electroplating wastewater. The presence of acrylic acid on the coir pith surface was verified by a scanning electron microscope with an electron dispersive x-ray spectrometer (SEM/EDX), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). The carbonyl groups (C==O) from the carboxylic acids (COOH) increased on the coir pith surface after grafting with acrylic acid. In addition, the thermal stability of the acrylic acid-grafted coir pith also improved. The optimum conditions for grafting the acrylic acid on the coir pith consisted of 2 M acrylic acid and 0.00125 M ceric ammonium nitrate (CAN, as an initiator). The maximum Cr(VI) removal (99.99 ± 0.07%) was obtained with the following conditions: a 1.3% (w/v) dosage of acrylic acid-grafted coir pith, a system pH of 2, a contact time of 22 h, a temperature of 30 °C, a particle size of <150 μm and an initial Cr(VI) of 1,171 mg l(-1). At system pH of 2, Cr(VI) in the HCrO(4)(-) form can be adsorbed with acrylic acid-grafted coir pith via an electrostatic attraction. The adsorption isotherm of 2 M acrylic acid-grafted coir pith exhibited a good fit with the Langmuir isotherm. The maximum Cr(VI) adsorption capacity of the 2 M acrylic acid-grafted coir pith was 196.00 mg Cr(VI) g(-1) adsorbent, whereas for coir pith without grafting, the maximum Cr(VI) removal was 165.00 mg Cr(VI) g(-1) adsorbent. The adsorption capacity of the acrylic acid-grafted coir pith for Cr(VI) was higher compared to the original coir pith. This result was due to the enhancement of the carbonyl groups on the coir pith surface that may have involved the mechanism of chromium adsorption. The X-ray absorption near edged structure (XANES) and desorption studies suggested that most of the Cr(III) that presented on the acrylic acid-grafted coir pith was due to the Cr(VI) being reduced to Cr(III) on the adsorbent surface. FTIR

  12. Optimizing the application of magnetic nanoparticles in Cr(VI) removal

    Science.gov (United States)

    Simeonidis, Konstantinos; Kaprara, Efthymia; Mitrakas, Manassis; Tziomaki, Magdalini; Angelakeris, Mavroidis; Vourlias, Georgios; Andritsos, Nikolaos

    2013-04-01

    The presence of heavy metals in aqueous systems is an intense health and environmental problem as implied by their harmful effects on human and other life forms. Among them, chromium is considered as an acutely hazardous compound contaminating the surface water from industrial wastes or entering the groundwater, the major source of drinking water, by leaching of chromite rocks. Chromium occurs in two stable oxidation states, Cr(III) and Cr(VI), with the hexavalent form being much more soluble and mobile in water having the ability to enter easily into living tissues or cells and thus become more toxic. Despite the established risks from Cr(VI)-containing water consumption and the increasing number of incidents, the E.U. tolerance limit for total chromium in potable water still stands at 50 μg/L. However, in the last years a worldwide debate concerning the establishment of a separate and very strict limit for the hexavalent form takes place. In practice, Cr(VI) is usually removed from water by various methods such as chemical coagulation/filtration, ion exchange, reverse osmosis and adsorption. Adsorption is considered as the simplest method which may become very effective if the process is facilitated by the incorporation of a Cr(VI) to Cr(III) reduction stage. This work studies the potential of using magnetic nanoparticles as adsorbing agents for Cr(VI) removal at the concentration levels met in contaminated drinking water. A variety of nanoparticles consisting of ferrites MFe2O4 (M=Fe, Co, Ni, Cu, Mn, Mg, Zn) were prepared by precipitating the corresponding bivalent or trivalent sulfate salts under controlled acidity and temperature. Electron microscopy and X-ray diffraction techniques were used to verify their crystal structure and determine the morphological characteristics. The mean particle size of the samples was found in the range 10-50 nm. Batch Cr(VI) removal tests were performed in aqueous nanoparticles dispersions showing the efficiency of ferrite

  13. Glycosylation of the N-terminal potential N-glycosylation sites in the human α1,3-fucosyltransferase V and -VI (hFucTV and -VI)

    DEFF Research Database (Denmark)

    Christensen, Lise Lotte; Bross, Peter Gerd; Ørntoft, Torben Falck

    2000-01-01

    Human alpha1,3-fucosyltransferase V and -VI (hFucTV and -VI) each contain four potential N-glycosylation sites (hFucTV: Asn60, Asn105, Asn167 and Asn198 and hFucTVI: Asn46, Asn91, Asn153 and Asn184). Glycosylation of the two N-terminal potential N-glycosylation sites (hFucTV: Asn60, Asn105 and h......FucTVI: Asn46 and Asn91) have never been studied in detail. In the present study, we have analysed the glycosylation of these potential N-glycosylation sites. Initially, we compared the molecular mass of hFucTV and -VI expressed in COS-7 cells treated with tunicamycin with the mass of the proteins...... in untreated cells. The difference in molecular mass between the proteins in treated and untreated cells corresponded to the presence of at least three N-linked glycans. We then made a series of mutants, in which the asparagine residues in the N-terminal potential N-glycosylation sites were replaced...

  14. Prevention of typhoid fever in Nepal with the Vi capsular polysaccharide of Salmonella typhi. A preliminary report.

    Science.gov (United States)

    Acharya, I L; Lowe, C U; Thapa, R; Gurubacharya, V L; Shrestha, M B; Cadoz, M; Schulz, D; Armand, J; Bryla, D A; Trollfors, B

    1987-10-29

    We conducted a pilot study followed by a large clinical trial in Nepal of the use of the capsular polysaccharide of Salmonella typhi (Vi) as a vaccine to prevent typhoid fever. In the pilot study, involving 274 Nepalese, there were no significant side effects of the Vi vaccine; about 75 percent responded with a rise in serum antibodies of fourfold or more. In the clinical trial, residents of five villages were given intramuscular injections of either Vi or, as a control, pneumococcus vaccine dispensed in coded, randomly arranged, single-dose syringes. There were 6907 participants, of whom 6438 were members of the target population (5 to 44 years of age); each was visited every two days. Those with temperatures of 37.8 degrees C or higher for three consecutive days were examined and asked to give blood for culture. Typhoid was diagnosed as either blood culture-positive or clinically suspected on the basis of bradycardia, splenomegaly, and fever, with a negative blood culture. Seventeen months after vaccination, the codes were broken for the 71 patients meeting the criteria for either culture-positive or clinically suspected typhoid. The attack rate of typhoid was 16.2 per 1000 among the controls and 4.1 per 1000 among those immunized with Vi (P less than 0.00001). The efficacy of Vi was 72 percent in the culture-positive cases, 80 percent in the clinically suspected cases, and 75 percent in the two groups combined. These data provide evidence that Vi antibodies confer protection against typhoid. Surveillance continues to determine the duration of Vi-induced immunity.

  15. A HISTÓRIA DAS GUERRAS: UM ESTUDO SOBRE AS DESCRIÇÕES DOS BÁRBAROS EM PROCÔPIO DE CESAREIA - SÉCULO VI THE HISTORY OF THE WARS: A STUDY ABOUT THE DESCRIPTIONS OF THE BARBARIANS IN PROCOPIUS -SIXTH CENTURY

    Directory of Open Access Journals (Sweden)

    Renato Viana Boy

    2011-10-01

    Full Text Available Este artigo propõe um estudo da obra História das Guerras, escrita por Procópio de Cesareia no século VI, que narra as conquistas bizantinas de Justiniano no Mediterrâneo e oriente persa. O objetivo é analisar como suas descrições dos povos bárbaros podem ser entendidas como uma narrativa comprometida e, ao mesmo tempo, submetida ao projeto imperial de expansão de fronteiras.This article proposes a study about the book History of the Wars, writing by Procopius of Caesarea in the sixth century, which narrates th Byzantines achievements of Justinian at Mediterranean and Eastern Persia. The goal is to analyze how the descriptions of Procopius about the barbarian people can be understood as a narrative committed and, at the same time, subjected to the imperial project of expanding boundaries.

  16. Defective collagen VI α6 chain expression in the skeletal muscle of patients with collagen VI-related myopathies

    Science.gov (United States)

    Tagliavini, F.; Pellegrini, C.; Sardone, F.; Squarzoni, S.; Paulsson, M.; Wagener, R.; Gualandi, F.; Trabanelli, C.; Ferlini, A.; Merlini, L.; Santi, S.; Maraldi, N.M.; Faldini, C.; Sabatelli, P.

    2014-01-01

    Collagen VI is a non-fibrillar collagen present in the extracellular matrix (ECM) as a complex polymer; the mainly expressed form is composed of α1, α2 and α3 chains; mutations in genes encoding these chains cause myopathies known as Ullrich congenital muscular dystrophy (UCMD), Bethlem myopathy (BM) and myosclerosis myopathy (MM). The collagen VI α6 chain is a recently identified component of the ECM of the human skeletal muscle. Here we report that the α6 chain was dramatically reduced in skeletal muscle and muscle cell cultures of genetically characterized UCMD, BM and MM patients, independently of the clinical phenotype, the gene involved and the effect of the mutation on the expression of the “classical” α1α2α3 heterotrimer. By contrast, the collagen VI α6 chain was normally expressed or increased in the muscle of patients affected by other forms of muscular dystrophy, the overexpression matching with areas of increased fibrosis. In vitro treatment with TGF-β1, a potent collagen inducer, promoted the collagen VI α6 chain deposition in the ECM of normal muscle cells, whereas, in cultures derived from collagen VI-related myopathy patients, the collagen VI α6 chain failed to develop a network outside the cells and accumulated in the endoplasmic reticulum. The defect of the α6 chain points to a contribution to the pathogenesis of collagen VI-related disorders. PMID:24907562

  17. Energizing Future Studies. Futures Information Interchange, Vol. V, No. 1, December 1977 [And] The Best from Futures Information Interchange, Vol. V, No. 2, April 1978 [And] Futures Information Interchange, Vol. VI, No. 1, 1978 [And] Futures Information Interchange, Vol. VI, No. 2, 1979.

    Science.gov (United States)

    Massachusetts Univ., Amherst. School of Education.

    The document is comprised of four newsletters which present a collection of essays, practical teaching methods, and learning activities introducing future studies into the classroom. Aimed at primary and secondary teachers, subject areas include forecasting methods, curriculum implementation and evaluation, innovative teaching materials and…

  18. Comparison of decay and yield data between JNDC2 and ENDF/B-VI

    Energy Technology Data Exchange (ETDEWEB)

    Oyamatsu, K.; Sagosaka, M.; Miyazono, T. [Nagoya Univ. (Japan)

    1997-03-01

    This work is intended to be our first step to solve disagreements of the decay heat powers between measurements and summation calculations. We examine differences between nuclear data libraries to complement our uncertainty evaluation of the decay heat summation calculations only with ENDF/B-VI. The comparison is made mainly between JNDC2 and ENDF/B-VI while JEF2.2 decay data is also discussed. In this study, we propose and use a simple method which is an analogue of the overlap integral of two wave functions in quantum mechanics. As the first step, we compare the whole input nuclear data for the summation calculations as a whole. We find a slight difference of the fission yields especially for high-energy neutron induced fissions between JNDC2 and ENDF/B-VI. As for the decay energies, JNDC2, ENDF/B-VI are quite similar while JEF2.2 is found significantly different from these two libraries. We find substantial differences in the decay constant values among the three libraries. As the second step, we calculate the decay heat powers with FPGS90 using JNDC2 and ENDF/B-VI. The total decay heat powers with the two libraries differ by more than 10% at short cooling times while they agree well on the average at cooling times longer that 100 (s). We also point out nuclides whose contributions are significantly different between the two libraries even though the total decay heats agree well. These nuclides may cause some problems in predicting aggregate spectra of {beta} and {gamma} rays as well as delayed neutrons, and are to be reviewed in the future revision of decay and yield data. (author)

  19. Selective and sensitive detection of chromium(VI) in waters using electrospray ionization mass spectrometry.

    Science.gov (United States)

    Weldy, Effie; Wolff, Chloe; Miao, Zhixin; Chen, Hao

    2013-09-01

    From 2000 through 2011, there were 14 criminal cases of violations of the Clean Water Act involving the discharge of chromium, a toxic heavy metal, into drinking and surface water sources. As chromium(VI), a potential carcinogen present in the environment, represents a significant safety concern, it is currently the subject of an EPA health risk assessment. Therefore, sensitive and selective detection of this species is highly desired. This study reports the analysis of chromium(VI) in water samples by electrospray ionization mass spectrometry (ESI-MS) following its reduction and complexation with ammonium pyrrolidinedithiocarbamate (APDC). The reduction and subsequent complexation produce a characteristic [Cr(III)O]-PDC complex which can be detected as a protonated ion of m/z 507 in the positive ion mode. The detection is selective to chromium(VI) under acidic pH, even in the presence of chromium(III) and other metal ions, providing high specificity. Different water samples were examined, including deionized, tap, and river waters, and sensitive detection was achieved. In the case of deionized water, quantification over the concentration range of 3.7 to 148ppb gave an excellent correlation coefficient of 0.9904 using the enhanced MS mode scan. Using the single-reaction monitoring (SRM) mode (monitoring the characteristic fragmentation of m/z 507 to m/z 360), the limit of detection (LOD) was found to be 0.25ppb. The LOD of chromium(VI) for both tap and river water samples was determined to be 2.0ppb. A preconcentration strategy using simple vacuum evaporation of the aqueous sample was shown to further improve the ESI signal by 15 fold. This method, with high sensitivity and selectivity, should provide a timely solution for the real-world analysis of toxic chromium(VI).

  20. Gene expression profiling identifies molecular pathways associated with collagen VI deficiency and provides novel therapeutic targets.

    Directory of Open Access Journals (Sweden)

    Sonia Paco

    Full Text Available Ullrich congenital muscular dystrophy (UCMD, caused by collagen VI deficiency, is a common congenital muscular dystrophy. At present, the role of collagen VI in muscle and the mechanism of disease are not fully understood. To address this we have applied microarrays to analyse the transcriptome of UCMD muscle and compare it to healthy muscle and other muscular dystrophies. We identified 389 genes which are differentially regulated in UCMD relative to controls. In addition, there were 718 genes differentially expressed between UCMD and dystrophin deficient muscle. In contrast, only 29 genes were altered relative to other congenital muscular dystrophies. Changes in gene expression were confirmed by real-time PCR. The set of regulated genes was analysed by Gene Ontology, KEGG pathways and Ingenuity Pathway analysis to reveal the molecular functions and gene networks associated with collagen VI defects. The most significantly regulated pathways were those involved in muscle regeneration, extracellular matrix remodelling and inflammation. We characterised the immune response in UCMD biopsies as being mainly mediated via M2 macrophages and the complement pathway indicating that anti-inflammatory treatment may be beneficial to UCMD as for other dystrophies. We studied the immunolocalisation of ECM components and found that biglycan, a collagen VI interacting proteoglycan, was reduced in the basal lamina of UCMD patients. We propose that biglycan reduction is secondary to collagen VI loss and that it may be contributing towards UCMD pathophysiology. Consequently, strategies aimed at over-expressing biglycan and restore the link between the muscle cell surface and the extracellular matrix should be considered.

  1. Gene Expression Profiling Identifies Molecular Pathways Associated with Collagen VI Deficiency and Provides Novel Therapeutic Targets

    Science.gov (United States)

    Paco, Sonia; Kalko, Susana G.; Jou, Cristina; Rodríguez, María A.; Corbera, Joan; Muntoni, Francesco; Feng, Lucy; Rivas, Eloy; Torner, Ferran; Gualandi, Francesca; Gomez-Foix, Anna M.; Ferrer, Anna; Ortez, Carlos; Nascimento, Andrés; Colomer, Jaume; Jimenez-Mallebrera, Cecilia

    2013-01-01

    Ullrich congenital muscular dystrophy (UCMD), caused by collagen VI deficiency, is a common congenital muscular dystrophy. At present, the role of collagen VI in muscle and the mechanism of disease are not fully understood. To address this we have applied microarrays to analyse the transcriptome of UCMD muscle and compare it to healthy muscle and other muscular dystrophies. We identified 389 genes which are differentially regulated in UCMD relative to controls. In addition, there were 718 genes differentially expressed between UCMD and dystrophin deficient muscle. In contrast, only 29 genes were altered relative to other congenital muscular dystrophies. Changes in gene expression were confirmed by real-time PCR. The set of regulated genes was analysed by Gene Ontology, KEGG pathways and Ingenuity Pathway analysis to reveal the molecular functions and gene networks associated with collagen VI defects. The most significantly regulated pathways were those involved in muscle regeneration, extracellular matrix remodelling and inflammation. We characterised the immune response in UCMD biopsies as being mainly mediated via M2 macrophages and the complement pathway indicating that anti-inflammatory treatment may be beneficial to UCMD as for other dystrophies. We studied the immunolocalisation of ECM components and found that biglycan, a collagen VI interacting proteoglycan, was reduced in the basal lamina of UCMD patients. We propose that biglycan reduction is secondary to collagen VI loss and that it may be contributing towards UCMD pathophysiology. Consequently, strategies aimed at over-expressing biglycan and restore the link between the muscle cell surface and the extracellular matrix should be considered. PMID:24223098

  2. Multinary I-III-VI2 and I2-II-IV-VI4 Semiconductor Nanostructures for Photocatalytic Applications.

    Science.gov (United States)

    Regulacio, Michelle D; Han, Ming-Yong

    2016-03-15

    Semiconductor nanostructures that can effectively serve as light-responsive photocatalysts have been of considerable interest over the past decade. This is because their use in light-induced photocatalysis can potentially address some of the most serious environmental and energy-related concerns facing the world today. One important application is photocatalytic hydrogen production from water under solar radiation. It is regarded as a clean and sustainable approach to hydrogen fuel generation because it makes use of renewable resources (i.e., sunlight and water), does not involve fossil fuel consumption, and does not result in environmental pollution or greenhouse gas emission. Another notable application is the photocatalytic degradation of nonbiodegradable dyes, which offers an effective way of ridding industrial wastewater of toxic organic pollutants prior to its release into the environment. Metal oxide semiconductors (e.g., TiO2) are the most widely studied class of semiconductor photocatalysts. Their nanostructured forms have been reported to efficiently generate hydrogen from water and effectively degrade organic dyes under ultraviolet-light irradiation. However, the wide band gap characteristic of most metal oxides precludes absorption of light in the visible region, which makes up a considerable portion of the solar radiation spectrum. Meanwhile, nanostructures of cadmium chalcogenide semiconductors (e.g., CdS), with their relatively narrow band gap that can be easily adjusted through size control and alloying, have displayed immense potential as visible-light-responsive photocatalysts, but the intrinsic toxicity of cadmium poses potential risks to human health and the environment. In developing new nanostructured semiconductors for light-driven photocatalysis, it is important to choose a semiconducting material that has a high absorption coefficient over a wide spectral range and is safe for use in real-world settings. Among the most promising candidates

  3. Vi behøver innovation

    DEFF Research Database (Denmark)

    McAloone, Tim C.

    2007-01-01

    . Især hvad angår vores forbrugsmønstre. Her er der behov for at kongeriget Danmark med sine 13 ton CO2-emission pr. person om året lytter. I landet hvor kraftvarmeproduk­tion, vindturbiner og industrial ecology i form af Kalundborg eksperimentet blev født, bør vi ikke også ride på denne nye miljøbølge......? Den amerikanske videnskabsmand Jeremy Rifkin beskriver i sin seneste bog, The European Dream, hvordan europæisk energipolitik, -forskning, -udvikling og relateret industri kan hjælpe os til at bremse vores for øjeblikket eksponentielt stigende CO2-produktion - og hvordan vores globaliseringstankegang...... rent faktisk kan fremme denne indsats. Den eneste udfordring er, at nogen skal igangsætte en økonomisk/industriel revolution, for at drømmen går i opfyldelse. Hvem skal tage ansvar for at sætte denne revolution i gang, og hvordan skal den opnås? Rifkin's patentløsning er inspirerende. Den er kort...

  4. Elliptic Schlesinger system and Painleve VI

    Energy Technology Data Exchange (ETDEWEB)

    Chernyakov, Yu [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Levin, A M [Institute of Oceanology, Moscow (Russian Federation); Olshanetsky, M [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Zotov, A [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation)

    2006-09-29

    We consider an elliptic generalization of the Schlesinger system (ESS) with positions of marked points on an elliptic curve and its modular parameter as independent variables (the parameters in the moduli space of the complex structure). This system was originally discovered by Takasaki (hep-th/9711095) in the quasi-classical limit of the SL(N) vertex model. Our derivation is purely classical. ESS is defined as a symplectic quotient of the space of connections of bundles of degree 1 over the elliptic curves with marked points. The ESS is a non-autonomous Hamiltonian system with pairwise commuting Hamiltonians. The system is bi-Hamiltonian with respect to the linear and introduced here quadratic Poisson brackets. The latter are the multi-colour form of the Sklyanin-Feigin-Odesski classical algebras. The ESS is the monodromy independence condition on the complex structure for the linear systems related to the flat bundle. The case of four points for a special initial data is reduced to the Painleve VI equation in the form of the Zhukovsky-Volterra gyrostat, proposed in our previous paper.

  5. A new MoVI Schiff base complex: methanol[N′-(3-methoxy-2-oxidobenzylidenebenzohydrazidato]dioxidomolybdenum(VI

    Directory of Open Access Journals (Sweden)

    Iran Sheikhshoaie

    2011-07-01

    Full Text Available In the title benzilidene Schiff base molybdenum(VI complex, [Mo(C15H12N2O3O2(CH3OH], the MoVI ion is coordinated by two oxide O atoms and by two O atoms and one N atom of the tridentate N′-(3-methoxy-2-oxidobenzylidenebenzohydrazidate (L Schiff base ligand. The methanol O atom completes the distorted octahedral configuration of the MoVI atom. Strong O—H...N hydrogen bonds form a C(5 chain around a 21 screw axis. Weak C—H—O hydrogen bonds are also present.

  6. A Ca(2+) chelator ameliorates chromium (VI)-induced hepatocyte L-02 injury via down-regulation of voltage-Dependent anion channel 1 (VDAC1) expression.

    Science.gov (United States)

    Yi, Xing; Xiao, Fang; Zhong, Xiali; Duan, Yujie; Liu, Kaihua; Zhong, Caigao

    2017-01-01

    Hexavalent chromium could result in cell malfunctions. Intracellular Ca(2+) ([Ca(2+)]i) content and VDAC1 expression are both important features related to cell survial. This study aimed to explore the mechanism of cell injury induced by Cr(VI) and tentatively offer clues to repairing this cell damage using [Ca(2+)]i and VDAC1. L-02 hepatocytes were treated with Cr(VI)/BAPTA, and the levels of [Ca(2+)]i and cell injury associated with Cr(VI) were determined in addition to the effect of BAPTA. The expression of VDAC1 in Cr(VI)-induced cells was evaluated. The results showed a dose-dependent elevation of the level of VDAC1 and the mRNA level of the VDAC1 biogenesis-related gene Sam50. BAPTA could ameliorate less severe damage induced by 4μM Cr(VI) via reducing VDAC1 and Sam50. Additionally, cell injury caused by less than 4μM Cr(VI) could be ameliorated by VDAC1 knockdown. Taken together, the findings of this study suggest that inhibition of intracellular Ca(2±) overload could protect cells from damage and that VDAC1 plays a considerable role in Cr(VI)-induced liver injury.

  7. Biosorption of Cr(VI) and As(V) at high concentrations by organic and inorganic wastes

    Science.gov (United States)

    María Rivas Pérez, Ivana; Paradelo Núñez, Remigio; Nóvoa Muñoz, Juan Carlos; Arias Estévez, Manuel; José Fernández Sanjurjo, María; Álvarez Rodríguez, Esperanza; Núñez Delgado, Avelino

    2016-04-01

    The potential reutilization of several wastes as biosorbents for As(V) and Cr(VI) has been assessed in batch-type experiments. The materials studied were one inorganic: mussel shell, and three organic: pine bark, oak ash and hemp waste. Batch experiments were performed in order to determine the removal capacity of the wastes under conditions of high As(V) and Cr(VI) loads. For this, 3 g of each waste material were added with 30 mL NaNO3 0.01 M dissolutions containing 0, 0.5, 1.5, 3 and 6 mmol As(V) L-1 or Cr(VI) L-1, prepared from analytical grade Na2HAsO4 or K2Cr2O7. The resulting suspensions were shaken for 24 h, centrifuged and filtered. Once each batch experiment corresponding to the sorption trials ended, each individual sample was added with 30 mL of NaNO3 0.01 M to desorb As(V) or Cr(VI), shaken for 24 h, centrifuged and filtered as in the sorption trials. Oak ash showed high sorption (>76%) and low desorption (hemp waste (98%) with very low desorption (hemp waste and mussel shell, that presented very low Cr(VI) sorption (<10%). Sorption data for both elements were better described by the Freundlich than by the Langmuir model. The variable results obtained for the removal of the two anionic contaminants for a given sorbent suggest that different mechanisms govern removal from the solution in each case. In summary, oak ash would be an efficient sorbent material for As(V), but not for Cr(VI), while pine bark would be the best sorbent for Cr(VI) removal.

  8. Experience with Salmonella typhi Vi capsular polysaccharide vaccine.

    Science.gov (United States)

    Hessel, L; Debois, H; Fletcher, M; Dumas, R

    1999-09-01

    Typhoid fever remains an important health threat in many parts of the world, with an estimated 16 million cases and 600,000 deaths occurring each year. The emergence of Salmonella typhi strains multiply resistant to antibiotics has complicated the treatment of this disease. Field experience of 8 years shows that a vaccine composed of purified Vi capsular polysaccharide of Salmonella typhi, given as a single intramuscular or deep subcutaneous injection, has consistent immunogenicity and efficacy. Side effects, based on reports since 1989, are infrequent and mild. Furthermore, the Vi vaccine may be administered simultaneously with other common "travel" vaccines, at two different sites of injection, without affecting immunogenicity and tolerability. This review presents an update of the development and clinical experience with the Salmonella typhi Vi polysaccharide vaccine (Typhim Vi; Pasteur Mérieux Connaught, France).

  9. Mechanism of uranium (VI) removal by two anaerobic bacterial communities

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Monica [Centro de Ciencias do Mar, Universidade do Algarve, FCT-DQF (edificio 8), Campus de Gambelas, 8005-139 Faro (Portugal); Faleiro, Maria Leonor [IBB - Centro de Biomedicina Molecular e Estrutural, Universidade do Algarve, FCT, Campus de Gambelas, 8005-139 Faro (Portugal); Costa, Ana M. Rosa da [Centro de Investigacao em Quimica do Algarve, Universidade do Algarve, FCT, DQF, Campus de Gambelas, 8005-139 Faro (Portugal); Chaves, Sandra; Tenreiro, Rogerio [Universidade de Lisboa, Faculdade de Ciencias, Centro de Biodiversidade, Genomica Integrativa e Funcional (BioFIG), Campus de FCUL, Campo Grande, 1749-016 Lisboa (Portugal); Matos, Antonio Pedro [Servico de Anatomia Patologica, Hospital Curry Cabral, Lisboa (Portugal); Costa, Maria Clara, E-mail: mcorada@ualg.pt [Centro de Ciencias do Mar, Universidade do Algarve, FCT-DQF (edificio 8), Campus de Gambelas, 8005-139 Faro (Portugal)

    2010-12-15

    The mechanism of uranium (VI) removal by two anaerobic bacterial consortia, recovered from an uncontaminated site (consortium A) and other from an uranium mine (consortium U), was investigated. The highest efficiency of U (VI) removal by both consortia (97%) occurred at room temperature and at pH 7.2. Furthermore, it was found that U (VI) removal by consortium A occurred by enzymatic reduction and bioaccumulation, while the enzymatic process was the only mechanism involved in metal removal by consortium U. FTIR analysis suggested that after U (VI) reduction, U (IV) could be bound to carboxyl, phosphate and amide groups of bacterial cells. Phylogenetic analysis of 16S rRNA showed that community A was mainly composed by bacteria closely related to Sporotalea genus and Rhodocyclaceae family, while community U was mainly composed by bacteria related to Clostridium genus and Rhodocyclaceae family.

  10. Identification and geochemical modeling of processes controlling leaching of Cr(VI) and other major elements from chromite ore processing residue

    Science.gov (United States)

    Geelhoed, Jeanine S.; Meeussen, Johannes C. L.; Hillier, Stephen; Lumsdon, David G.; Thomas, Rhodri P.; Farmer, John G.; Paterson, Edward

    2002-11-01

    Chromite ore processing residue (COPR) contains very high levels of chromium as Cr(III) and Cr(VI) and has a pH of ˜11.5 to 12. Millions of tonnes of COPR have in the past been deposited in urban areas. We have studied the factors that control leaching of Cr(VI), Ca, Al, Si, and Mg from COPR by means of batch experiments, mineralogical characterization of COPR via X-ray powder diffraction and scanning electron microscopy, and chemical equilibrium modeling. Batch experiments at a range of pH values and two liquid:solid ratios showed that mineral solubility control exists for aqueous concentrations of Cr(VI) above pH 10. Calculations indicate that the solid phases that control the solubility of Cr(VI) at pH values above 11 are Cr(VI)-substituted hydrogarnet (Ca 3Al 2(H 4O 4,CrO 4) 3) and Cr(VI)-hydrocalumite (Ca 4Al 2(OH) 12CrO 4·6 H 2O), a layered double-hydroxide clay with chromate anions held in the interlayers. In the pH range 9.5 to 11, the description of the Cr(VI) concentration in solution was strongly improved by the incorporation in the model of Cr(VI)-ettringite (Ca 6Al 2(OH) 12(CrO 4) 3·26 H 2O), which precipitates as a secondary phase when hydrocalumite dissolves. The proposed model for leaching of COPR at high pH includes Cr(VI)-bearing hydrogarnet, Cr(VI)-hydrocalumite, Cr(VI)-ettringite, brucite, calcite, Ca 2Al 2(OH) 10·3 H 2O, CaH 2SiO 4, and gehlenite hydrate (Ca 2Al 2(OH) 6SiO 8H 8·H 2O). The model accurately predicts the concentrations of Cr(VI), Ca, Al, Si, and Mg in solution in the pH range 10 to 12 as well as the pH-buffering behavior. Below pH 8, a decrease in the Cr(VI) concentration in solution is observed, which may be attributed to sorption of chromate onto freshly precipitated Al and Fe hydroxide surfaces. Sulfate and carbonate show the same type of behavior as chromate. The chemistry of COPR shows similarities with cement and high-pH municipal waste incinerator bottom ash.

  11. Plan of propagation and communication experiments using ETS-VI

    Science.gov (United States)

    Ohmori, Shingo

    1988-01-01

    In 1992, an Engineering Test Satellite VI is scheduled to be launched by an H-II rocket. The missions of ETS-VI are to establish basic technologies of inter-satellite communications using millimeter waves and optical beams and fix satellite communications using multibeam antenna on board the satellite. Several kinds of frequency bands will be used for the communications missions. However, these frequencies can be used for propagation experiments.

  12. Gender Features of Intellectual Development of Students of VI-X Classes

    OpenAIRE

    Sorokova M.G.,; Ermakov S.S.

    2015-01-01

    The study was conducted as part of the monitoring of giftedness, organized by the City Resource Centre of Giftedness, Moscow State University of Psychology & Education, in 2012. One of the objectives of the study was the identification of gender-specific intelligence in high school students at different grade levels. The sample size was 2023 students of VI-X grades from 24 schools in Moscow, including 990 boys and 1033 girls. Intelligence was measured using Raven's "Standard Progressive Matri...

  13. Polyurethane-Keratin Membranes: Structural Changes by Isocyanate and pH, and the Repercussion on Cr(VI Removal

    Directory of Open Access Journals (Sweden)

    María D. Manrique-Juárez

    2013-01-01

    Full Text Available Keratin has the capacity to interact with metal ions. In order to take advantage of this potential, a novel membrane with polyurethane and keratin has been developed and studied for removal of Cr(VI from aqueous solution. Physicochemical and morphological properties of these hybrid membranes were studied, varying synthesis parameters such as the type of isocyanate and pH in keratin solution. The effects of using diphenyl-methane-diisocyanate or toluene-diisocyanate and modifying the pH in keratin solutions were evaluated by scanning electron microscopy, Fourier transform infrared spectroscopy, and dynamical mechanical analysis. Results show that pH has a strong influence on morphology and on Cr(VI removal efficiency. When pH in keratin solution is low (2.5, the protein separates from water, and a more closed cell in the membrane is obtained affecting its mechanical properties. The removal efficiency of Cr(VI was also assessed at different pH values of chromium solutions. These results show that when pH of the Cr solution is acidic (at 1.5, the Cr(VI removal percentages increase significantly, reaching up to a 58%. Thus this paper demonstrates the successful combination of synthetic and natural polymers depending on the process parameters to be applied in the critical purpose of remediation of Cr(VI contamination.

  14. Influence of dynamical conditions on the reduction of U(VI) at the magnetite-solution interface.

    Science.gov (United States)

    Ilton, Eugene S; Boily, Jean-François; Buck, Edgar C; Skomurski, Frances N; Rosso, Kevin M; Cahill, Christopher L; Bargar, John R; Felmy, Andrew R

    2010-01-01

    The heterogeneous reduction of U(VI) to U(IV) by ferrous iron is believed to be a key process influencing the fate and transport of U in the environment. The reactivity of both sorbed and structural Fe(II) has been studied for numerous substrates, including magnetite. Published results from U(VI)-magnetite experiments have been variable, ranging from no reduction to clear evidence for the formation of U(IV). In this contribution, we used XAS and high resolution (+/-cryogenic) XPS to study the interaction of U(VI) with nanoparticulate magnetite. The results indicated that U(VI) was partially reduced to U(V) with no evidence of U(IV). However, thermodynamic calculations indicated that U phases with average oxidation states below (V) should have been stable, indicating that the system was not in redox equilibrium. A reaction pathway that involves incorporation and stabilization of U(V) and U(VI) into secondary phases is invoked to explain the observations. The results suggest an important and previously unappreciated role of U(V) in the fate and transport of uranium in the environment.

  15. Versatility of Streptomyces sp. M7 to bioremediate soils co-contaminated with Cr(VI) and lindane.

    Science.gov (United States)

    Aparicio, JuanDaniel; Solá, María Zoleica Simón; Benimeli, Claudia Susana; Amoroso, María Julia; Polti, Marta Alejandra

    2015-06-01

    The aim of this work was to study the impact of environmental factors on the bioremediation of Cr(VI) and lindane contaminated soil, by an actinobacterium, Streptomyces sp. M7, in order to optimize the process. Soil samples were contaminated with 25 µg kg(-1) of lindane and 50 mg kg(-1) of Cr(VI) and inoculated with Streptomyces sp. M7. The lowest inoculum concentration which simultaneously produced highest removal of Cr(VI) and lindane was 1 g kg(-1). The influence of physical and chemical parameters was assessed using a full factorial design. The factors and levels tested were: Temperature: 25, 30, 35°C; Humidity: 10%, 20%, 30%; Initial Cr(VI) concentration: 20, 50, 80 mg kg(-1); Initial lindane concentration: 10, 25, 40 µg kg(-1). Streptomyces sp. M7 exhibited strong versatility, showing the ability to bioremediate co-contaminated soil samples at several physicochemical conditions. Streptomyces sp. M7 inoculum size was optimized. Also, it was fitted a model to study this process, and it was possible to predict the system performance, knowing the initial conditions. Moreover, optimum temperature and humidity conditions for the bioremediation of soil with different concentrations of Cr(VI) and lindane were determined. Lettuce seedlings were a suitable biomarker to evaluate the contaminants mixture toxicity. Streptomyces sp. M7 carried out a successful bioremediation, which was demonstrated through ecotoxicity test with Lactuca sativa.

  16. Selective adsorption of molybdenum(VI) from Mo-Re bearing effluent by chemically modified astringent persimmon.

    Science.gov (United States)

    Xiong, Ying; Wang, Haitao; Lou, Zhenning; Shan, Weijun; Xing, Zhiqiang; Deng, Guichun; Wu, Dongbei; Fang, Dawei; Biswas, Biplob Kumar

    2011-02-28

    Astringent persimmon was chemically cross-linked by formaldehyde to obtain a novel kind of adsorption gel, which was named as APF gel. The adsorption behaviors of Mo(VI) and Re(VII) along with other coexisting metals onto the APF gel were studied in the present paper. The APF gel was found to be effective for the adsorption of Mo(VI) while the gel is almost completely inert toward rhenium and calcium over the whole hydrochloric acid concentration region. The APF gel has a low affinity for iron, copper, lead, nickel, manganese and zinc ions when the concentration of HCl is higher than 1 mol/L. The gel exhibited selectivity only for Mo(VI) with a remarkably high adsorption capacity 1.05 mol/kg, and the adsorption behavior obeys the Langmuir model. According to the thermodynamic and kinetic studies, the endothermic adsorption process followed pseudo-second order kinetics. Also, its excellent adsorption characteristics for Mo(VI) were confirmed by the adsorption and elution tests using a column packed with the APF gel. The result provides a new approach for the recovery of Mo(VI) from a industrial waste effluent.

  17. THE INFLUENCE OF POTASSIUM DICHROMATE Cr (VI ADMINISTRATION DURATION ON GLOBULAR RESISTANCE IN FEMALE RATS

    Directory of Open Access Journals (Sweden)

    LETIŢIA STANA

    2013-07-01

    Full Text Available The „in vivo” experiment has had as aim the study of different Cr(VI doses administration on globular resistance in female rats related to administration duration. Study was carried out on 56 female rats divided in 8 groups, 6 experimental and 2 control that received potassium dichromate in drinking water in doses of 25 ppm, 50 ppm and 75ppm Cr(VI, for 3 months, respectively, 6 months. Decrease of globular resistance (in terms of haemolysis degree in hypotonic solutions at increasing dose (up to 0.8% NaCl at 75 ppm dose in all experimental groups, in direct relation with the duration of administration was registered. Control groups were in physiological limits. The results of the present study revealed the affecting of erythrocyte membrane in function of administration duration and chromium intake level, because of oxidative lesions produced by it.

  18. Sorption of Cr(VI) by Amberlite XAD-7 resin impregnated with brilliant green and its determination by quercetin as a selective spectrophotometric reagent.

    Science.gov (United States)

    Hosseini, Mohammad Saeid; Hosseini-Bandegharaei, Ahmad; Raissi, Haidar; Belador, Foroogh

    2009-09-30

    A new chelating polymeric sorbent as an extractant-impregnated resin (EIR) has been developed using brilliant green (BG) and Amberlite XAD-7 resin. The BG-impregnated resin showed superior binding affinity for Cr(VI) in the presence of many co-existing ions and no considerable interference was observed. The influence of various physicochemical parameters on the recovery of Cr(VI) were optimized by both static and dynamic methods. The Langmuir adsorption isotherm gave a satisfactory fit of the equilibrium data. The kinetic studies performed for Cr(VI) sorption revealed that 93%, which confirmed accuracy of the measurements.

  19. Assessment of genotoxic potential of Cr(VI) in the mouse duodenum: an in silico comparison with mutagenic and nonmutagenic carcinogens across tissues.

    Science.gov (United States)

    Thompson, Chad M; Gregory Hixon, J; Proctor, Deborah M; Haws, Laurie C; Suh, Mina; Urban, Jonathan D; Harris, Mark A

    2012-10-01

    In vitro studies on hexavalent chromium [Cr(VI)] indicate that reduced forms of this metal can interact with DNA and cause mutations. Recently, Cr(VI) was shown to induce intestinal tumors in mice; however, Cr(VI) elicited redox changes, cytotoxicity and hyperplasia - suggesting involvement of tissue injury rather than direct mutagenesis. Moreover, toxicogenomic analyses indicated limited evidence for DNA damage responses. Herein, we extend these toxicogenomic analyses by comparing the gene expression patterns elicited by Cr(VI) with those of four mutagenic and four nonmutagenic carcinogens. To date, toxicogenomic profiles for mutagenic and nonmutagenic duodenal carcinogens do not exist, thus duodenal gene changes in mice were compared to those elicited by hepatocarcinogens. Specifically, duodenal gene changes in mice following exposure to Cr(VI) in drinking water were compared to hepatic gene changes previously identified as potentially discriminating mutagenic and nonmutagenic hepatocarcinogens. Using multivariate statistical analyses (including logistic regression classification), the Cr(VI) gene responses clustered apart from mutagenic carcinogens and closely with nonmutagenic carcinogens. These findings are consistent with other intestinal data supporting a nonmutagenic mode of action (MOA). These findings may be useful as part of a full weight of evidence MOA evaluation for Cr(VI)-induced intestinal carcinogenesis. Limitations to this analysis will also be discussed.

  20. Short-term exposure of nontumorigenic human bronchial epithelial cells to carcinogenic chromium(VI) compromises their respiratory capacity and alters their bioenergetic signature.

    Science.gov (United States)

    Cerveira, Joana F; Sánchez-Aragó, María; Urbano, Ana M; Cuezva, José M

    2014-01-01

    Previous studies on the impact of hexavalent chromium [Cr(VI)] on mammalian cell energetics revealed alterations suggestive of a shift to a more fermentative metabolism. Aiming at a more defined understanding of the metabolic effects of Cr(VI) and of their molecular basis, we assessed the impact of a mild Cr(VI) exposure on critical bioenergetic parameters (lactate production, oxygen consumption and intracellular ATP levels). Cells derived from normal human bronchial epithelium (BEAS-2B cell line), the main in vivo target of Cr(VI) carcinogenicity, were subjected for 48 h to 1 μM Cr(VI). We could confirm a shift to a more fermentative metabolism, resulting from the simultaneous inhibition of respiration and stimulation of glycolysis. This shift was accompanied by a decrease in the protein levels of the catalytic subunit (subunit β) of the mitochondrial H(+)-ATP synthase (β-F1-ATPase) and a concomitant marked increase in those of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The corresponding alteration in the β-F1-ATPase/GAPDH protein ratio (viewed as a bioenergetic signature) upon Cr(VI) exposure was in agreement with the observed attenuation of cellular respiration and enhancement of glycolytic flux. Altogether, these results constitute a novel finding in terms of the molecular mechanisms of Cr(VI) effects.

  1. Short-term exposure of nontumorigenic human bronchial epithelial cells to carcinogenic chromium(VI compromises their respiratory capacity and alters their bioenergetic signature

    Directory of Open Access Journals (Sweden)

    Joana F. Cerveira

    2014-01-01

    Full Text Available Previous studies on the impact of hexavalent chromium [Cr(VI] on mammalian cell energetics revealed alterations suggestive of a shift to a more fermentative metabolism. Aiming at a more defined understanding of the metabolic effects of Cr(VI and of their molecular basis, we assessed the impact of a mild Cr(VI exposure on critical bioenergetic parameters (lactate production, oxygen consumption and intracellular ATP levels. Cells derived from normal human bronchial epithelium (BEAS-2B cell line, the main in vivo target of Cr(VI carcinogenicity, were subjected for 48 h to 1 μM Cr(VI. We could confirm a shift to a more fermentative metabolism, resulting from the simultaneous inhibition of respiration and stimulation of glycolysis. This shift was accompanied by a decrease in the protein levels of the catalytic subunit (subunit β of the mitochondrial H+-ATP synthase (β-F1-ATPase and a concomitant marked increase in those of glyceraldehyde-3-phosphate dehydrogenase (GAPDH. The corresponding alteration in the β-F1-ATPase/GAPDH protein ratio (viewed as a bioenergetic signature upon Cr(VI exposure was in agreement with the observed attenuation of cellular respiration and enhancement of glycolytic flux. Altogether, these results constitute a novel finding in terms of the molecular mechanisms of Cr(VI effects.

  2. Speciation, liquid-liquid extraction, sequential separation, preconcentration, transport and ICP-AES determination of Cr(III), Mo(VI) and W(VI) with calix-crown hydroxamic acid in high purity grade materials and environmental samples.

    Science.gov (United States)

    Agrawal, Y K; Sharma, K R

    2005-07-15

    A new functionalized calix[6]crown hydroxamic acid is reported for the speciation, liquid-liquid extraction, sequential separation and trace determination of Cr(III), Mo(VI) and W(VI). Chromium(III), molybdenum(VI) and tungsten(VI) are extracted at pH 4.5, 1.5M HCl and 6.0M HCl, respectively with calixcrown hydroxamic acid (37,38,39,40,41,42-hexahydroxy7,25,31-calix[6]crown hydroxamic acid) in chloroform in presence of large number of cations and anions. The extraction mechanism is investigated. The various extraction parameters, appropriate pH/M HCl, choice of solvent, effect of the reagent concentration, temperature and distribution constant have been studied. The speciation, preconcentration and kinetic of transport has been investigated. The maximum transport is observed 35, 45 and 30min for chromium(III), molybdenum(VI) and tungsten(IV), respectively. For trace determination the extracts were directly inserted into the plasma for inductively coupled plasma atomic emission spectrometry, ICP-AES, measurements of chromium, molybdenum and tungsten which increase the sensitivity by 30-fold, with detection limits of 3ngml(-1). The method is applied for the determination of chromium, molybdenum and tungsten in high purity grade ores, biological and environmental samples. The chromium was recovered from the effluent of electroplating industries.

  3. Vi har intet lært - hvornår lærer vi det?

    DEFF Research Database (Denmark)

    Sodemann, Morten

    2016-01-01

    WHO anså fra i går ikke længere ebola for at være en trussel mod global folkesundhed, så fra i dag er kameraerne slukket i Vestafrika og vi er tilbage hvor vi startede. SDG målene skal have et dansk udtryk, men hvad er de danske kompetencer på globalt plan når sundhed ikke længere er en kerneakti......WHO anså fra i går ikke længere ebola for at være en trussel mod global folkesundhed, så fra i dag er kameraerne slukket i Vestafrika og vi er tilbage hvor vi startede. SDG målene skal have et dansk udtryk, men hvad er de danske kompetencer på globalt plan når sundhed ikke længere er en...

  4. Designing and implementing a Quality Broker: the GeoViQua experience

    Science.gov (United States)

    Papeschi, Fabrizio; Bigagli, Lorenzo; Masò, Joan; Nativi, Stefano

    2014-05-01

    GeoViQua (QUAlity aware VIsualisation for the Global Earth Observation System of Systems) is an FP7 project aiming at complementing the Global Earth Observation System of Systems (GEOSS) with rigorous data quality specifications and quality-aware capabilities, in order to improve reliability in scientific studies and policy decision-making. GeoViQua main scientific and technical objective is to enhance the GEOSS Common Infrastructure (GCI) providing the user community with innovative quality-aware search and visualization tools, which will be integrated in the GEOPortal, as well as made available to other end-user interfaces. To this end, GeoViQua will promote the extension of the current standard metadata for geographic information with accurate and expressive quality indicators. Employing and extending several ISO standards such as 19115, 19157 and 19139, a common set of data quality indicators has been selected to be used within the project. The resulting work, in the form of a data model, is expressed in XML Schema Language and encoded in XML. Quality information can be stated both by data producers and by data users, actually resulting in two conceptually distinct data models, the Producer Quality model and the User Quality model (or User Feedback model). GeoViQua architecture is built on the brokering approach successfully experimented within the EuroGEOSS project and realized by the GEO DAB (Discovery and Access Broker) which is part of the GCI. The GEO DAB allows for harmonization and distribution in a transparent way for both users and data providers. This way, GeoViQua can effectively complement and extend the GEO DAB obtaining a Quality augmentation Broker (DAB-Q) which plays a central role in ensuring the consistency of the Producer and User quality models. The GeoViQua architecture also includes a Feedback Catalog, a particular service brokered by the DAB-Q which is dedicated to the storage and discovery of user feedbacks. A very important issue

  5. Removal of chromium(VI) from wastewater using phosphoric acid treated activated carbon

    Science.gov (United States)

    Suganthi, N.

    2013-06-01

    Activated carbon prepared by phosphoric acid treatment of tamarind nuts (seeds) was investigated for the removal of Cr(VI) from aqueous solutions. The characteristics of phosphorylated tamarind nut carbon (PTNC) were evaluated for porosity and surface area. The effect of contact time, pH, adsorbent dose and particle size variation were studied to evaluate the potential applicability of carbon for treating Cr(VI) containing wastewater. The adsorbent data were modeled by Langmiur and Freundlich classical adsorption isotherms. The kinetic studies showed that Cr(VI) adsorption on PTNC was in compliance with the pseudo-second-order kinetic model. Desorption studies indicated that ion-exchange mechanism was operating. The continuous adsorption was studied in glass columns of 2.5 cm diameter using electroplating wastewater to ascertain the practical applicability of PTNC in large scale. The mechanism of adsorption was found to be ion-exchange process and was supported by FTIR spectroscopy. The surface modification after adsorption was confirmed by SEM studies.

  6. ZnO-PLLA Nanofiber Nanocomposite for Continuous Flow Mode Purification of Water from Cr(VI

    Directory of Open Access Journals (Sweden)

    T. Burks

    2015-01-01

    Full Text Available Nanomaterials of ZnO-PLLA nanofibers have been used for the adsorption of Cr(VI as a prime step for the purification of water. The fabrication and application of the flexible ZnO-PLLA nanofiber nanocomposite as functional materials in this well-developed architecture have been achieved by growing ZnO nanorod arrays by chemical bath deposition on synthesized electrospun poly-L-lactide nanofibers. The nanocomposite material has been tested for the removal and regeneration of Cr(IV in aqueous solution under a “continuous flow mode” by studying the effects of pH, contact time, and desorption steps. The adsorption of Cr(VI species in solution was greatly dependent upon pH. SEM micrographs confirmed the successful fabrication of the ZnO-PLLA nanofiber nanocomposite. The adsorption and desorption of Cr(VI species were more likely due to the electrostatic interaction between ZnO and Cr(VI ions as a function of pH. The adsorption and desorption experiments utilizing the ZnO-PLLA nanofiber nanocomposite have appeared to be an effective nanocomposite in the removal and regeneration of Cr(VI species.

  7. Evaluation of the bioremoval of Cr(VI) and TOC in biofilters under continuous operation using response surface methodology.

    Science.gov (United States)

    Leles, Daniela M A; Lemos, Diego A; Filho, Ubirajara C; Romanielo, Lucienne L; de Resende, Miriam M; Cardoso, Vicelma L

    2012-06-01

    In the present study, the bioremoval of Cr(VI) and the removal of total organic carbon (TOC) were achieved with a system composed by an anaerobic filter and a submerged biofilter with intermittent aeration using a mixed culture of microorganisms originating from contaminated sludge. In the aforementioned biofilters, the concentrations of chromium, carbon, and nitrogen were optimized according to response surface methodology. The initial concentration of Cr(VI) was 137.35 mg l(-1), and a bioremoval of 85.23% was attained. The optimal conditions for the removal of TOC were 4 to 8 g l(-1) of sodium acetate, >0.8 g l(-1) of ammonium chloride and 60 to 100 mg l(-1) of Cr(VI). The results revealed that ammonium chloride had the strongest effect on the TOC removal, and 120 mg l(-1) of Cr(VI) could be removed after 156 h of operation. Moreover, 100% of the Cr(VI) and the total chromium content of the aerobic reactor output were removed, and TOC removals of 80 and 87% were attained after operating the anaerobic and aerobic reactors for 130 and 142 h, respectively. The concentrations of cells in both reactors remained nearly constant over time. The residence time distribution was obtained to evaluate the flow through the bioreactors.

  8. Groundwater contaminated with hexavalent chromium [Cr (VI]: a health survey and clinical examination of community inhabitants (Kanpur, India.

    Directory of Open Access Journals (Sweden)

    Priti Sharma

    Full Text Available BACKGROUND: We assessed the health effects of hexavalent chromium groundwater contamination (from tanneries and chrome sulfate manufacturing in Kanpur, India. METHODS: The health status of residents living in areas with high Cr (VI groundwater contamination (N = 186 were compared to residents with similar social and demographic features living in communities having no elevated Cr (VI levels (N = 230. Subjects were recruited at health camps in both the areas. Health status was evaluated with health questionnaires, spirometry and blood hematology measures. Cr (VI was measured in groundwater samples by diphenylcarbazide reagent method. RESULTS: Residents from communities with known Cr (VI contamination had more self-reports of digestive and dermatological disorders and hematological abnormalities. GI distress was reported in 39.2% vs. 17.2% males (AOR = 3.1 and 39.3% vs. 21% females (AOR = 2.44; skin abnormalities in 24.5% vs. 9.2% males (AOR = 3.48 and 25% vs. 4.9% females (AOR = 6.57. Residents from affected communities had greater RBCs (among 30.7% males and 46.1% females, lower MCVs (among 62.8% males and less platelets (among 68% males and 72% females than matched controls. There were no differences in leucocytes count and spirometry parameters. CONCLUSIONS: Living in communities with Cr (VI groundwater is associated with gastrointestinal and dermatological complaints and abnormal hematological function. Limitations of this study include small sample size and the lack of long term follow-up.

  9. Removal of chromium from Cr(VI) polluted wastewaters by reduction with scrap iron and subsequent precipitation of resulted cations.

    Science.gov (United States)

    Gheju, M; Balcu, I

    2011-11-30

    This work presents investigations on the total removal of chromium from Cr(VI) aqueous solutions by reduction with scrap iron and subsequent precipitation of the resulted cations with NaOH. The process was detrimentally affected by a compactly passivation film occurred at scrap iron surface, mainly composed of Cr(III) and Fe(III). Maximum removal efficiency of the Cr(total) and Fe(total) achieved in the clarifier under circumneutral and alkaline (pH 9.1) conditions was 98.5% and 100%, respectively. The optimum precipitation pH range which resulted from this study is 7.6-8.0. Fe(total) and Cr(total) were almost entirely removed in the clarifier as Fe(III) and Cr(III) species; however, after Cr(VI) breakthrough in column effluent, chromium was partially removed in the clarifier also as Cr(VI), by coprecipitation with cationic species. As long the column effluent was free of Cr(VI), the average Cr(total) removal efficiency of the packed column and clarifier was 10.8% and 78.8%, respectively. Our results clearly indicated that Cr(VI) contaminated wastewater can be successfully treated by combining reduction with scrap iron and chemical precipitation with NaOH.

  10. The influence of Chromium supplied by tanning and wet finishing processes on the formation of cr(vi in leather

    Directory of Open Access Journals (Sweden)

    W. F. Fuck

    2011-06-01

    Full Text Available Chromium used in leather manufacturing can be oxidized from the trivalent to the hexavalent state, causing environmental concerns. In this study, the influence of Cr(III from tanning, deacidification pH, fatliquors, chrome retanning and vegetable retanning on the formation of Cr(VI in leather was analyzed by comparing natural and aged samples. In wet-blue leather, even after aging and in fatliquored leathers that did not suffer the aging process, the presence of Cr(VI was always below the detection limit of 3 mg/kg. Considering the presence of Cr(VI, the supply of chromium during the retanning step had a more significant effect than during the tanning. In the fatliquoring process with sulfites, fish and synthetic fatliquor leather samples contained Cr(VI when aged, and the highest concentration detected was 26.7 mg/kg. The evaluation of Cr(VI formation led to recommendations for regulation in the leather industry.

  11. Modification of chitosan by swelling and crosslinking using epichlorohydrin as heavy metal Cr (VI) adsorbent in batik industry wastes

    Science.gov (United States)

    Hastuti, B.; Masykur, A.; Hadi, S.

    2016-02-01

    Study on chitosan modification by swelling and crosslinking and its application as a selective adsorbent for heavy metals Cr (VI) in batik industry wastes was done. Swelling is intended to improve chitosan porosity, whereas crosslinking is to increase the resistance of chitosan against acid. Natural samples are generally acidic, thus limiting chitosan application as an adsorbent. Modification of chitosan by combining swelling and crosslinking is expected to increase its adsorption capacity in binding heavy metal ions in water. The modified chitosan was later contacted with Cr (VI) to test its adsorption capacity with a variation of pH and contact time. Finally, application of modified chitosan was done in batik industry waste containing Cr (IV). Based on the results, chitosan-ECH 25% (v/v) was the optimum concentration of crosslinker to adsorb Cr (VI) ions. Modified chitosan has a solubility resistance to acids, even though a strong acid. Modification of chitosan also improved its adsorption capacity to Cr (VI) from 74% (pure chitosan) to 89% with contact time 30 min at pH 3. On the application to the batik wastes, the modified chitosan were able to adsorb Cr (IV) up to the level of 5 ppm. Thus, the modified chitosan has a potential to be applied to as an adsorbent of Cr (VI) in batik industry wastes.

  12. Interactions between Silicon Oxide Nanoparticles (SONPs) and U(VI) Contaminations: Effects of pH, Temperature and Natural Organic Matters.

    Science.gov (United States)

    Wu, Hanyu; Li, Ping; Pan, Duoqiang; Yin, Zhuoxin; Fan, Qiaohui; Wu, Wangsuo

    2016-01-01

    The interactions between contaminations of U(VI) and silicon oxide nanoparticles (SONPs), both of which have been widely used in modern industry and induced serious environmental challenge due to their high mobility, bioavailability, and toxicity, were studied under different environmental conditions such as pH, temperature, and natural organic matters (NOMs) by using both batch and spectroscopic approaches. The results showed that the accumulation process, i.e., sorption, of U(VI) on SONPs was strongly dependent on pH and ionic strength, demonstrating that possible outer- and/or inner-sphere complexes were controlling the sorption process of U(VI) on SONPs in the observed pH range. Humic acid (HA), one dominated component of NOMs, bounded SONPs can enhance U(VI) sorption below pH~4.5, whereas restrain at high pH range. The reversible sorption of U(VI) on SONPs possibly indicated that the outer-sphere complexes were prevalent at pH 5. However, an irreversible interaction of U(VI) was observed in the presence of HA (Fig 1). It was mainly due to the ternary SONPs-HA-U(VI) complexes (Type A Complexes). After SONPs adsorbed U(VI), the particle size in suspension was apparently increased from ~240 nm to ~350 nm. These results showed that toxicity of both SONPs and U(VI) will decrease to some extent after the interaction in the environment. These findings are key for providing useful information on the possible mutual interactions among different contaminants in the environment.

  13. Interactions between Silicon Oxide Nanoparticles (SONPs and U(VI Contaminations: Effects of pH, Temperature and Natural Organic Matters.

    Directory of Open Access Journals (Sweden)

    Hanyu Wu

    Full Text Available The interactions between contaminations of U(VI and silicon oxide nanoparticles (SONPs, both of which have been widely used in modern industry and induced serious environmental challenge due to their high mobility, bioavailability, and toxicity, were studied under different environmental conditions such as pH, temperature, and natural organic matters (NOMs by using both batch and spectroscopic approaches. The results showed that the accumulation process, i.e., sorption, of U(VI on SONPs was strongly dependent on pH and ionic strength, demonstrating that possible outer- and/or inner-sphere complexes were controlling the sorption process of U(VI on SONPs in the observed pH range. Humic acid (HA, one dominated component of NOMs, bounded SONPs can enhance U(VI sorption below pH~4.5, whereas restrain at high pH range. The reversible sorption of U(VI on SONPs possibly indicated that the outer-sphere complexes were prevalent at pH 5. However, an irreversible interaction of U(VI was observed in the presence of HA (Fig 1. It was mainly due to the ternary SONPs-HA-U(VI complexes (Type A Complexes. After SONPs adsorbed U(VI, the particle size in suspension was apparently increased from ~240 nm to ~350 nm. These results showed that toxicity of both SONPs and U(VI will decrease to some extent after the interaction in the environment. These findings are key for providing useful information on the possible mutual interactions among different contaminants in the environment.

  14. Correlation between bulk- and surface chemistry of Cr-tanned leather and the release of Cr(III) and Cr(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Hedberg, Yolanda S., E-mail: yolanda@kth.se [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, SE-10044 Stockholm (Sweden); Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-17177 Stockholm (Sweden); Lidén, Carola, E-mail: carola.liden@ki.se [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-17177 Stockholm (Sweden); Odnevall Wallinder, Inger, E-mail: ingero@kth.se [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, SE-10044 Stockholm (Sweden)

    2014-09-15

    Graphical abstract: - Highlights: • Released reducing/complexing leather-specific species can reduce released Cr(VI). • No co-released species enable the formation of Cr(VI) in solution. • The major Cr species released from leather in phosphate buffer was Cr(III) (>82%). • No Cr(VI) was released into artificial sweat. - Abstract: About 1–3% of the adult general population in Europe is allergic to chromium (Cr). The assessment of the potential release of Cr(III) and Cr(VI) from leather is hence important from a human health and environmental risk perspective. The Cr(VI) content in leather was recently restricted in the European Union. The aim of this study was to assess possible correlations between the bulk and surface chemistry of leather, released Cr(III) and Cr(VI), and capacities of co-released leather specific species to reduce and complex released Cr. Four differently tanned leathers were characterized by scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and the diphenylcarbazide colorimetric method. Their characteristics were compared with results on Cr(III) and Cr(VI) release into artificial sweat (ASW, pH < 6.5) and phosphate buffer (PB, pH 7.5–8.0), measured by means of spectrophotometry and atomic absorption spectroscopy. Co-released leather-specific species were shown to reduce Cr(VI), both in ASW and in PB. Their reduction capacities correlated with findings of the surface content of Cr and of released Cr. Leather samples without this capacity, and with less aromatic surface groups visible by ATR-FTIR, revealed Cr(VI) both at the surface and in solution (PB)

  15. Interactions between Silicon Oxide Nanoparticles (SONPs) and U(VI) Contaminations: Effects of pH, Temperature and Natural Organic Matters

    Science.gov (United States)

    Wu, Hanyu; Li, Ping; Pan, Duoqiang; Yin, Zhuoxin; Fan, Qiaohui; Wu, Wangsuo

    2016-01-01

    The interactions between contaminations of U(VI) and silicon oxide nanoparticles (SONPs), both of which have been widely used in modern industry and induced serious environmental challenge due to their high mobility, bioavailability, and toxicity, were studied under different environmental conditions such as pH, temperature, and natural organic matters (NOMs) by using both batch and spectroscopic approaches. The results showed that the accumulation process, i.e., sorption, of U(VI) on SONPs was strongly dependent on pH and ionic strength, demonstrating that possible outer- and/or inner-sphere complexes were controlling the sorption process of U(VI) on SONPs in the observed pH range. Humic acid (HA), one dominated component of NOMs, bounded SONPs can enhance U(VI) sorption below pH~4.5, whereas restrain at high pH range. The reversible sorption of U(VI) on SONPs possibly indicated that the outer-sphere complexes were prevalent at pH 5. However, an irreversible interaction of U(VI) was observed in the presence of HA (Fig 1). It was mainly due to the ternary SONPs-HA-U(VI) complexes (Type A Complexes). After SONPs adsorbed U(VI), the particle size in suspension was apparently increased from ~240 nm to ~350 nm. These results showed that toxicity of both SONPs and U(VI) will decrease to some extent after the interaction in the environment. These findings are key for providing useful information on the possible mutual interactions among different contaminants in the environment. PMID:26930197

  16. Remoção de cromo (VI de soluções aquosas utilizando o compósito magnético calcinado hidrotalcita-óxido de ferro: estudo cinético e de equilíbrio termodinâmico Removal of chromium (VI from aqueous solutions using the calcined magnetic composite hydrotalcite-iron oxide: kinetic and thermodynamic equilibrium studies

    Directory of Open Access Journals (Sweden)

    Thiago Vinícius Toledo

    2013-01-01

    Full Text Available In this work, hydrotalcite, a layered double hydroxide, had its ion exchange properties combined with the magnetic properties of iron oxide to produce a magnetic adsorbent, HT-Fe 500. These magnetic composites can be used as adsorbents for anionic contaminants in water and subsequently removed from the medium by a simple magnetic process. Removal of chromium (VI from aqueous solutions using HT-Fe 500 was achieved using batch adsorption experiments. The adsorption capacity, calculated with the Langmuir-Freundlich model showed to be dependent on temperature, reaching values of 25.93 and 48.31 mg g-1, respectively, for temperatures of 25 and 30 ºC.

  17. Experimental study and modelling of the U(VI)-NaCl-H{sub 2}O ternary system with respect to pH and NaCl concentration at T=155 degrees C and Psat; Etude experimentale et modelisation du systeme ternaire U(VI)-NaCl-H{sub 2}O en fonction du pH et de la concentration en NaCl, a T = 155C et Psat

    Energy Technology Data Exchange (ETDEWEB)

    Rozsypal, Ch.; Chinh, Nguyen-Trung [CREGU, 54 - Vandoeuvre les Nancy (France); Cuney, M. [Universite Henri Poincare - Nancy 1, UMR 7566 G2R, 54 - Vandoeuvre-les-Nancy (France)

    2009-07-01

    The authors report an experimental investigation of the solubility of U(VI) in the UO{sub 3}-NaCl-H{sub 2}O ternary system with respect to the pH (between 2.9 and 13.4) at a temperature of 155 C. The average experiment duration has been 4 months in an acid medium and 6 months in a basic medium. At the end of these experiments, solid phases have been analysed by X-ray diffraction, transmission and scanning electronic microscopy, and Raman spectroscopy. The content in dissolved uranium has been determined. The obtained results show that the initial UO{sub 3} transformed into three types of solid phases: uranium oxides in acid medium, uranates, and sodium chloro-uranates

  18. Investigation on Microbial Dissolution of Uranium (VI) from Autunite Mineral - 13421

    Energy Technology Data Exchange (ETDEWEB)

    Sepulveda, Paola; Katsenovich, Yelena; Lagos, Leonel [Applied Research Center, Florida International University. 10555 West Flagler St. Suite 2100, Miami Fl 33175 (United States)

    2013-07-01

    Precipitating autunite minerals by polyphosphate injection was identified as a feasible remediation strategy for sequestering uranium in contaminated groundwater and soil in situ at the Hanford Site. Autunite stability under vadose and saturated zone environmental conditions can help to determine the long-term effectiveness of this remediation strategy. The Arthrobacter bacteria are one of the most common groups in soils and are found in large numbers in Hanford soil as well as other subsurface environments contaminated with radionuclides. Ubiquitous in subsurface microbial communities, these bacteria can play a significant role in the dissolution of minerals and the formation of secondary minerals. The main objective of this investigation was to study the bacterial interactions under oxidizing conditions with uranium (VI); study the potential role of bicarbonate, which is an integral complexing ligand for U(VI) and a major ion in groundwater compositions; and present data from autunite dissolution experiments using Arthrobacter strain G968, a less U(VI)-tolerant strain. Sterile 100 mL glass mixed reactors served as the major bioreactor for initial experimentation. These autunite-containing bioreactors were injected with bacterial cells after the autunite equilibrated with the media solution amended with 0 mM, 3 mM 5 mM and 10 mM concentrations of bicarbonate. G968 Arthrobacter cells in the amount of 10{sup 6} cells/mL were injected into the reactors after 27 days, giving time for the autunite to reach steady state. Abiotic non-carbonate controls were kept without bacterial inoculation to provide a control for the biotic samples. Samples of the solution were analyzed for dissolved U(VI) by means of kinetic phosphorescence analyzer KPA-11 (Chemcheck Instruments, Richland, WA). Analysis showed that as [HCO{sub 3}{sup -}] increases, a diminishing trend on the effect of bacteria on autunite leaching is observed. Viability of cells was conducted after 24 hours of cell

  19. A systematic review of new advances in the management of mucopolysaccharidosis VI (Maroteaux-Lamy syndrome: focus on galsulfase

    Directory of Open Access Journals (Sweden)

    Regina P El Dib

    2009-09-01

    Full Text Available Regina P El Dib1, Gregory M Pastores21Department of Surgery, McMaster University, McMaster Institute of Urology, Hamilton, Ontario, Canada; 2Department of Neurology and Pediatrics, New York University School of Medicine, New York, NY, USAIntroduction: Mucopolysaccharidosis type VI (MPS VI, Maroteaux-Lamy syndrome is an autosomal recessive lysosomal storage disorder, characterized primarily by skeletal dysplasia and joint contracture. It is caused by a deficiency of N-acetylgalactosamine-4-sulfatase (arylsulfatase B, for which a recombinant formulation (galsulfase is available as replacement therapy. Objective: To evaluate the effectiveness and safety of galsulfase compared to placebo or no interventions, for treating MPS VI. We also considered studies evaluating different doses of galsulfase.Methods: A systematic review of the literature was conducted. A computerized electronic search in MEDLINE, EMBASE, CENTRAL, SciELO, and LILACS was carried on to identify any randomized trials that met our inclusion criteria.Results: Two studies were included in the review. Because the number of studies was small, our analysis probably did not find any statistically significant difference. Long-term follow-up will be required to ascertain full clinical benefit, on both event-free survival and quality of life measures.Conclusions: There is some evidence to support the use of galsulfase in the treatment of MPS VI; however due to the very low quantity of included studies we could not analyze it in an appropriate way. This review highlights the need for continued research into the use of enzyme replacement therapy for MPS VI.Keywords: mucopolysaccharidosis VI, Maroteaux-Lamy syndrome, galsulfase, naglazyme, systematic review

  20. Effect of the gamma irradiation on the bio-sorption of Cr (Vi) by orange peel;Efecto de la irradiacion gamma en la biosorcion de Cr(VI) por cascara de naranja

    Energy Technology Data Exchange (ETDEWEB)

    Lugo L, V.; Barrera D, C. E.; Sanchez M, V. [Universidad Autonoma del Estado de Mexico, Centro de Investigacion en Quimica Sustentable, Paseo Tollocan esquina Paseo Colon s/n, 50180 Toluca, Estado de Mexico (Mexico); Urena N, F., E-mail: violelugol@yahoo.e [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2009-07-01

    The orange peel (Citrus sp.) is a bioadsorbent that contains functional groups able to remove Cr (Vi). To study the effect of gamma irradiation in the sorption capacity, the Nn materials were irradiated with gamma rays using a Co{sup 60} source to dose from 10 to 3500 KGy (Nlgamma). The biomass irradiation with gamma rays was successful since it increased the hexavalent chromium removal obtaining a maximum removal percentage of 100%. Sorption isotherms were realized to determine the concentration effect of initial Cr (Vi), the ph effect of the solution and the relationship m/v. (Author)

  1. Selective removal of Cr(VI) from aqueous solution by polypyrrole/2,5-diaminobenzene sulfonic acid composite.

    Science.gov (United States)

    Kera, Nazia H; Bhaumik, Madhumita; Ballav, Niladri; Pillay, Kriveshini; Ray, Suprakas Sinha; Maity, Arjun

    2016-08-15

    A polypyrrole/2,5-diaminobenzenesulfonic acid (PPy/DABSA) composite, synthesised by the in situ oxidative polymerization of pyrrole in the presence of DABSA, was studied as an adsorbent for the removal of Cr(VI) from aqueous solution. The structure and morphology of the composite were investigated by ATR-FTIR, FE-SEM, EDX, TGA, XRD and XPS studies. The adsorption of Cr(VI) by PPy/DABSA composite was highly pH dependent and optimum removal was achieved at pH 2. Adsorption of Cr(VI) was confirmed by EDX and XPS studies. The isotherm data fitted the linear Langmuir model well, with a maximum adsorption capacity of 303mg/g at 25°C. Thermodynamic parameters (ΔG°, ΔH° and ΔS°) were calculated using isotherm data and confirmed that the adsorption process was spontaneous and endothermic. Adsorption kinetics was best described by the pseudo-second-order model. The activation energy of the adsorption process suggested that Cr(VI) was chemisorbed by PPy/DABSA composite. PPy/DABSA composite could be used for three consecutive adsorption-desorption cycles without loss of its original adsorption capacity. Highly selective removal of Cr(VI) was observed even when co-existing ions such as Cu(2+), Zn(2+), Ni(2+), Cl(-), SO4(2)(-) and NO3(-) were present in the solution. In summary, the potential of PPy/DABSA composite for remediating industrial wastewater contaminated by Cr(VI) has been demonstrated.

  2. Surface complexation modeling of U(VI) adsorption by aquifer sediments from a former mill tailings site at Rifle, Colorado

    Science.gov (United States)

    Hyun, S.P.; Fox, P.M.; Davis, J.A.; Campbell, K.M.; Hayes, K.F.; Long, P.E.

    2009-01-01

    A study of U(VI) adsorption by aquifer sediment samples from a former uranium mill tailings site at Rifle, Colorado, was conducted under oxic conditions as a function of pH, U(VI), Ca, and dissolved carbonate concentration. Batch adsorption experiments were performed using adsorption Kd values for the sand and adsorption data. The model successfully predicted U(VI) adsorption observed from a multilevel sampling well installed at the site. A comparison of the model with the one developed previously for a uranium mill tailings site at Naturita, Colorado, indicated that possible calcite nonequilibrium of dissolved calcium concentration should be evaluated. The modeling results also illustrate the importance of the range of data used in deriving the best fit model parameters. ?? 2009 American Chemical Society.

  3. Impaired antibody response after immunization of HIV-infected individuals with the polysaccharide vaccine against Salmonella typhi (Typhim-Vi).

    Science.gov (United States)

    Kroon, F P; van Dissel, J T; Ravensbergen, E; Nibbering, P H; van Furth, R

    1999-08-01

    Infections with Salmonella species, including Salmonella typhi, are more frequently observed in HIV-infected individuals than in healthy individuals. HIV-infected individuals were vaccinated with polysaccharide vaccine against Salmonella typhi (Typhim-Vi) which is assumed to be a T-cell-independent antigen. We found that the antibody response in patients with or = 200 x 10(6)/l CD4+ T lymphocytes and healthy controls. The antibody response after vaccination with the polysaccharide salmonella Vi-antigen was correlated with the number of CD4+ T lymphocytes and therefore Typhim-Vi can be considered to be a T-cell-independent type 2 antigen. The results of this study indicate that after vaccination the proportion of HIV-infected individuals with protective antibody concentrations against Salmonella typhi will be lower than in healthy controls.

  4. Total Reducing Capacity in Aquifer Minerals and Sediments: Quantifying the Potential to Attenuate Cr(VI) in Groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Sisman, S. Lara [Univ. of Virginia, Charlottesville, VA (United States); Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-07-20

    Hexavalent chromium, Cr(VI), is present in the environment as a byproduct of industrial processes. Due to its mobility and toxicity, it is crucial to attenuate or remove Cr(VI) from the environment. The objective of this investigation was to quantify potential natural attenuation, or reduction capacity, of reactive minerals and aquifer sediments. Samples of reduced-iron containing minerals such as ilmenite, as well as Puye Formation sediments representing a contaminated aquifer in New Mexico, were reacted with chromate. The change in Cr(VI) during the reaction was used to calculate reduction capacity. This study found that minerals that contain reduced iron, such as ilmenite, have high reducing capacities. The data indicated that sample history may impact reduction capacity tests due to surface passivation. Further, this investigation identified areas for future research including: a) refining the relationships between iron content, magnetic susceptibility and reduction capacity, and b) long term kinetic testing using fresh aquifer sediments.

  5. Incorporation of Np(V) and U(VI) in Carbonate and Sulfate Minerals Crystallized from Aqueous Solution

    Energy Technology Data Exchange (ETDEWEB)

    Balboni, Enrica; Morrison, Jessica M.; Wang, Zheming; Engelhard, Mark H.; Burns, Peter C.

    2015-02-15

    The neptunyl Np(V)O2 + and uranyl U(VI)O2 2+ ions are soluble in groundwater, although their interaction with minerals in the subsurface may impact their mobility. One mechanism for the immobilization of actinyl ions in the subsurface is coprecipitation in low-temperature minerals that form naturally, or that are induced to form as part of a remediation strategy. Important differences in the crystal-chemical behavior of the Np(V) neptunyl and U(VI) uranyl ions suggest their behavior towards incorporation into growing crystals may differ significantly. Using a selection of low temperature minerals synthesized in aqueous systems under ambient conditions, this study examines the factors that impact the structural incorporation of the Np(V) neptunyl and U(VI) uranyl ions in carbonate and sulfate minerals.

  6. The phosphine oxides Cyanex 921 and Cyanex 923 as carriers for facilitated transport of chromium (VI)-chloride aqueous solutions.

    Science.gov (United States)

    Alguacil, Francisco José; López-Delgado, Aurora; Alonso, Manuel; Sastre, Ana Maria

    2004-11-01

    The behaviour of the phosphine oxides Cyanex 921 and Cyanex 923 in the facilitated transport of chromium (VI) from chloride solutions is described. Transport is studied as a function of several variables such as stirring speeds of the aqueous phases, membrane phase diluent, hydrochloric acid concentration in the source phase and chromium and carrier concentrations. The separation of chromium (VI) from other metals presented in the source phase as well as the behaviour of phosphine oxides with respect to other neutral organophosphorous derivatives (tri-n-butylphosphate (TBP) and dibutyl butylphosphonate (DBBP)) are also investigated. Moreover, by using hydrazine sulphate in the receiving phase, Cr(VI) is immediately reduced to the less toxic Cr(III).

  7. Adsorption of U(VI from Aqueous Solution onto Hydrotalcite-Like Compounds

    Directory of Open Access Journals (Sweden)

    Nguyen Van Suc

    2012-01-01

    Full Text Available Uranium adsorption by the synthesized compound of magnesium aluminum hydroxide hydrate – layered double hydrotalcite (STH-like compounds was studied. The calcinated STH was proven to be a highly effective in U(VI adsorption in pH range from 6.5 to 7. The time dependent experimental data were found to be fit to the pseudo-second-oder model. The equilibrium data have been modeled using Langmuir and Freundlich isotherms. The results showed that both model provide the best correlation with equilibrium data. The highest adsorption capacity, approximated 62.5 mg/g, was observed in the calcinated STH at 500 °C. The positive value of enthalpy change indicated that adsorption reaction of U(VI on STH was endothermic process. The regeneration experiments of STH using 0.1M Na2CO3 solution was successfully demonstrated multiple times without any significant effect on the initial adsorption capacity.

  8. Optimization of Adsorption Conditions of Cr (VI by PEI Modified BSG Using Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Xinlong Jiang

    2015-02-01

    Full Text Available Surface response optimization of Adsorption Conditions of Cr (VI wastewater by PEI modified brewer's grains (BSG with the factors of pH value, adsorbent concentration, adsorption time, amount of adsorbent and the response of adsorption rate were studied. The optimal parameters for adsorption conditions were of adsorbent concentration of 113.30 mg/L, adsorbent particle size of 60~80 mesh, pH 1.79, adsorbent amount of 4.99 g/L, adsorption time and temperature of 1.88 h and 30°C, respectively. The maximal absorption rate got 100.0%, adsorption capacity was 46.58 mg/g. The PEI modified BSG is a promising, cheap, efficient, new biological materials of adsorption for Cr (VI in wastewater.

  9. A programmable DNA origami nanospring that reveals force-induced adjacent binding of myosin VI heads.

    Science.gov (United States)

    Iwaki, M; Wickham, S F; Ikezaki, K; Yanagida, T; Shih, W M

    2016-12-12

    Mechanosensitive biological nanomachines such as motor proteins and ion channels regulate diverse cellular behaviour. Combined optical trapping with single-molecule fluorescence imaging provides a powerful methodology to clearly characterize the mechanoresponse, structural dynamics and stability of such nanomachines. However, this system requires complicated experimental geometry, preparation and optics, and is limited by low data-acquisition efficiency. Here we develop a programmable DNA origami nanospring that overcomes these issues. We apply our nanospring to human myosin VI, a mechanosensory motor protein, and demonstrate nanometre-precision single-molecule fluorescence imaging of the individual motor domains (heads) under force. We observe force-induced transitions of myosin VI heads from non-adjacent to adjacent binding, which correspond to adapted roles for low-load and high-load transport, respectively. Our technique extends single-molecule studies under force and clarifies the effect of force on biological processes.

  10. Extraction of uranium (VI) from nitric acid solutions with N,N,-di-n-butyloctanamide

    Energy Technology Data Exchange (ETDEWEB)

    Dembinski, W.; Gasparini, G.M.

    1980-12-01

    N,N-dialkylamides show interesting properties as new extracting agents of actinides. This report presents the data concerning the N,N-di-n-butyloctanamide: CH/sub 3/-(CH/sub 2/)/sub 5/-CH/sub 2/-C(O)N (C/sub 4/H/sub 9/)/sub 2/. In particular the following have been studied: the formation of a third phase with n-dodecane and mesitylene as diluents; the influence of the concentration of the uranium of the nitric acid and of the extractant on the distribution coeffcient, of uranium(VI); the radiation stability of this amide and the influence of the absorbed dose on the distribution coefficient for U(VI). The general properties of the di-n-butyloctanamide as potential extractant of uranium are discussed.

  11. Detached-eddy simulation of flow around the NREL phase VI blade

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Sørensen, Niels N.; Michelsen, J.A.;

    2002-01-01

    –Stokes method in the boundary layer with a large-eddy simulation in the free shear flow. The present study focuses on static and dynamic stall regions highly relevant for stall-regulated wind turbines. Computations do predict force coefficients and pressure distributions fairly well. Results using detached-eddy......The detached-eddy simulation model implemented in the computational fluid dynamics code EllipSys3D is used to calculate the flow around the non-rotating NREL Phase VI wind turbine blade. Results are presented for flow around a parked blade at fixed angle of attack and a blade pitching along...... the blade axis. Computed blade characteristics are compared with experimental data from the NREL/NASA Ames Phase VI unsteady experiment. The detached-eddy simulation model is a method for predicting turbulence in computational fluid dynamics computations, which combines a Reynolds-averaged Navier...

  12. A programmable DNA origami nanospring that reveals force-induced adjacent binding of myosin VI heads

    Science.gov (United States)

    Iwaki, M.; Wickham, S. F.; Ikezaki, K.; Yanagida, T.; Shih, W. M.

    2016-01-01

    Mechanosensitive biological nanomachines such as motor proteins and ion channels regulate diverse cellular behaviour. Combined optical trapping with single-molecule fluorescence imaging provides a powerful methodology to clearly characterize the mechanoresponse, structural dynamics and stability of such nanomachines. However, this system requires complicated experimental geometry, preparation and optics, and is limited by low data-acquisition efficiency. Here we develop a programmable DNA origami nanospring that overcomes these issues. We apply our nanospring to human myosin VI, a mechanosensory motor protein, and demonstrate nanometre-precision single-molecule fluorescence imaging of the individual motor domains (heads) under force. We observe force-induced transitions of myosin VI heads from non-adjacent to adjacent binding, which correspond to adapted roles for low-load and high-load transport, respectively. Our technique extends single-molecule studies under force and clarifies the effect of force on biological processes. PMID:27941751

  13. Sorption of Uranium(VI and Thorium(IV by Jordanian Bentonite

    Directory of Open Access Journals (Sweden)

    Fawwaz I. Khalili

    2013-01-01

    Full Text Available Purification of raw bentonite was done to remove quartz. This includes mixing the raw bentonite with water and then centrifuge it at 750 rpm; this process is repeated until white purified bentonite is obtained. XRD, XRF, FTIR, and SEM techniques will be used for the characterization of purified bentonite. The sorption behavior of purified Jordanian bentonite towards and Th4+ metal ions in aqueous solutions was studied by batch experiment as a function of pH, contact time, temperature, and column techniques at 25.0∘C and . The highest rate of metal ions uptake was observed after 18 h of shaking, and the uptake has increased with increasing pH and reached a maximum at . Bentonite has shown high metal ion uptake capacity toward uranium(VI than thorium(IV. Sorption data were evaluated according to the pseudo- second-order reaction kinetic. Sorption isotherms were studied at temperatures 25.0∘C, 35.0∘C, and 45.0∘C. The Langmuir, Freundlich, and Dubinin-Radushkevich (D-R sorption models equations were applied and the proper constants were derived. It was found that the sorption process is enthalpy driven for uranium(VI and thorium(IV. Recovery of uranium(VI and thorium(IV ions after sorption was carried out by treatment of the loaded bentonite with different concentrations of HNO3 1.0 M, 0.5 M, 0.1 M, and 0.01 M. The best percent recovery for uranium(VI and thorium(IV was obtained when 1.0 M HNO3 was used.

  14. Molecular analysis of mucopolysaccharidosis type VI in Poland, Belarus, Lithuania and Estonia.

    Science.gov (United States)

    Jurecka, Agnieszka; Piotrowska, Ewa; Cimbalistiene, Loreta; Gusina, Nina; Sobczyńska, Agnieszka; Czartoryska, Barbara; Czerska, Kamila; Õunap, Katrin; Węgrzyn, Grzegorz; Tylki-Szymańska, Anna

    2012-02-01

    Mucopolysaccharidosis VI (MPS VI) is a rare autosomal recessive disorder caused by a deficiency of N-acetylgalactosamine-4-sulfatase (ARSB). Over 130 ARSB gene mutations have been identified thus far and most mutations are unique to individual families. We aimed to analyze the spectrum of mutations in the ARSB gene responsible for the disorder in Poland, Belarus and Baltic States. Twenty one families with MPS VI patients, in whom diagnosis was confirmed biochemically and enzymatically, were studied. Direct sequencing of patient genomic DNA was used to identify ARSB mutations. In total, fourteen different disease-causing mutations were found. Three novel mutations included insertion c.375_376insT, a missense mutation c.499G>A (p.G167R) and deletion/insertion c.750_754delinsCCTGAAGTCAAG. We also report 11 previously described mutations (p.A33V, p.W57C, p.Q88X, p.T92K, p.Q97X, p.R152W, p.R160Q, p.R160X, p.Y210C, p.Y266S, p.G302R). The mutation p.R152W was present at a high prevalence of 50% (21/42) the mutated alleles in this group of patients. High prevalence of p.R152W mutation in Poland, Belarus and Baltic States indicates a possible founder effect and suggests that screening for this mutation may be appropriate in MPS VI patients from this region. Our study has also provided evidence to support genotype-phenotype correlation.

  15. Synthesis of assorted metal ions anchored alginate bentonite biocomposites for Cr(VI) sorption.

    Science.gov (United States)

    Gopalakannan, Venkatrajan; Periyasamy, Soodamani; Viswanathan, Natrayasamy

    2016-10-20

    Biocomposites were synthesized by dispersing bentonite (Bent) clay in a biopolymer namely alginate (Alg) and cross-linked with bi (Ca(2+)), tri (Ce(3+)) and tetravalent (Zr(4+)) metal ions viz., Ca@AlgBent, Ce@AlgBent and Zr@AlgBent composites respectively. The synthesized biocomposites were characterized by various instrumental techniques like FTIR, SEM and EDAX. Cr(VI) sorption capacities (SCs) of the biocomposites Ca@AlgBent, Ce@AlgBent and Zr@AlgBent were examined by batch process. Various adsorption influencing factors viz., contact time, dosage of the sorbent, pH of the medium, temperature, presence of common co-ions and initial Cr(VI) concentration were studied. Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherm models were adopted to examine the adsorption equilibrium. Kinetics of the sorption process was carried out by pseudo-first-order and pseudo-second-order models. The nature of the sorption process was explained using thermodynamic parameters like ΔS°, ΔG° and ΔH° and a possible mechanism for the sorption of Cr(VI) onto the biocomposites was given. The application of the biocomposites at field conditions was also examined by testing it with industrial water. The regeneration studies were carried to know about the reusability of the biocomposites.

  16. The bark of holm oak (Quercus ilex, L.) for airborne Cr(VI) monitoring.

    Science.gov (United States)

    Minganti, Vincenzo; Drava, Giuliana; De Pellegrini, Rodolfo; Anselmo, Marco; Modenesi, Paolo; Malaspina, Paola; Giordani, Paolo

    2015-01-01

    In this work, the bark of holm oak was used as a bioindicator to study the atmospheric distribution of Cr(VI). The chosen method (alkaline extraction and atomic absorption determination) was found in the literature, adapted for use with the matrix involved, and validated. The method had some limits, but provided an excellent estimation of Cr(VI) concentrations with good sensitivity and a reasonable time of analysis and cost. Thirty-four samples of holm oak collected in three areas characterised by different possible sources of pollution (the area near a former chromate production plant, an urban area, and a rural "reference" area) were analysed, obtaining concentrations ranging from 1.54 to 502 μg g(-1) near the industrial plant, ranging from 0.22 to 1.35 μg g(-1) in the urban area, and mostly below the detection limit (0.04 μg g(-1)) in the rural area. The bark of holm oak proved to be a good bioindicator to detect Cr(VI) in the environment. The extraction procedure followed by atomic absorption analysis is simple, provides good sensitivity, and it is suitable for environmental studies.

  17. Sorption of lindane to river biofilms, suspended particles and sediments in the presence and absence of Cr(VI) and As(V)

    Science.gov (United States)

    Guo, Z.; Dong, D.; Hua, X.; Lan, X.; Liang, D.

    2013-12-01

    Few study has focused on the effects of Cr(VI) and As(V) which are often in the form of anionic groups in natural aquatic environment on the sorption of dissolved hydrophobic organic pollutants (HOPs) onto natural solid materials from water. In this study, we compared the sorption thermodynamics of lindene as a model dissolved HOP on biofilms, suspended particles and surface sediments collected from the same river in the presence and absence of Cr(VI) and As(V). Visual MINTEQ (version 3.0) was applied to calculate Cr(VI) and As(V) species in the sorption system. CrO42- (89%) was the main Cr(VI) species and HAsO42- (78%) and H2AsO4- (22%) were the As(V) species. Compared with Freundlich and the dual reactive domain model, linear model gave a better fit for the lindane sorption isotherms on the biofilms, particles and sediments (Fig.1). For the lindane sorption on the biofilms, the linear model distribution coefficient (KL) were reduced by 48.0% and 47.6% in the presence of Cr(VI) and As(V), respectively; For that on the suspended particles, KL were reduced by 6.2% and 10.8%, respectively; For the sediments, KL were reduced by 30.2% and 34.5%, respectively. In general, the presence of Cr(VI) and As(V) inhibited lindane sorption onto the three solids and inhibition level decreased in the order biofilms > sediments > particles. In contrast to the promotion of metal cations on the dissolved HOPs sorption onto natural solid materials, anionic Cr(VI) and As(V) groups suppressed the sorption. This indicated that anionic Cr(VI) and As(V) groups might occupy some sorption sites on solids and then occurred competitive sorption with lindane. Taking account of the errors in experiment, effects on the sorption between Cr(VI) and As(V) has no significant difference. This shown that the type of metal has little effect on the HOPs sorption onto natural solids. This result was consistent with that in other related studis. In addition, we inferred that the differences of component

  18. Mellya-Tamak VI Settlement of Chiyalik Culture

    Directory of Open Access Journals (Sweden)

    Kazakov Evgenii P.

    2016-06-01

    Full Text Available The authors publish the fi ndings of the digs on Mellya-Tamak VI temporary settlement belonging to the Chiyalik archaeological culture – one of the most comprehensively studied settlements in this complex of sites. Besides proper Chiyalik materials, some artefacts of Mesolithic-Neolithic, Early Iron Age (Pyany Bor culture and Early Middle Ages (Kushnarenkovo culture have been identifi ed here. The Chiyalik stage is represented by debris of a summer camp, with its surface structures, hearths, stones from wall cladding and household pits. The life time of the Chiyalik settlement on the Mellya-Tamak dune can be dated within the thirteenth-fourteenth centuries, as suggested by the authors based on some fi nds of glass beads with overlaid linear-undulate paste threads and the ceramic complex. As a result of years of research, the authors conclude that the Chiyalik sites were left by the Uralic Ugrians, who were part of the Golden Horde population and were undergoing the process of Islamization and Turkization.

  19. Tolerance and bioaccumulation of U(VI) by Bacillus mojavensis and its solid phase preconcentration by Bacillus mojavensis immobilized multiwalled carbon nanotube.

    Science.gov (United States)

    Özdemir, Sadin; Oduncu, M Kadir; Kilinc, Ersin; Soylak, Mustafa

    2017-02-01

    In this study, uranium(VI) tolerance and bioaccumulation were investigated by using thermo -tolerant Bacillus mojavensis. The level of U(VI) was measured by UV-VIS spectrophotometry. The minimum inhibition concentration (MIC) value of U(VI) was experimented. Bacterial growth was not affected in the presence of 1.0 and 2.5 mg/L U(VI) at 36 h and the growth was partially affected in the presence of 5 mg/L U(VI) at 24 h. What was obtained from this study is that there was diversity in the various periods of the growth phases of metal bioaccumulation capacity, which was shown by B. mojavensis. The maximum bioaccumulation capacities were found to be 12.8, 22.7, and 48.2 mg/g dried bacteria, at 24th hours at concentration of 1.0, 2.5 and 5 mg/L U(VI), respectively. In addition to these, U(VI) has been preconcentrated on B. mojavensis immobilized MWCNT. Several factors such as pH, flow rate of solution, amount of biosorbent and support materials, eluent type, concentration and volume, the matrix interference effect on retention have been studied, and extraction conditions were optimized. Preconcentration factor was achieved as 60. Under the optimized conditions, the limit of detection (LOD) and quantification (LOQ) were calculated as 0.74 and 2.47 μg/L. The biosorption capacity of immobilized B. mojavensis was calculated for U(VI) as 25.8 mg/g. The results demonstrated that the immobilized biosorbent column could be reused at least 30 cycles of biosorption and desorption with the higher than 95% recovery. FT-IR and SEM analysis were performed to understand the surface properties of B. mojavensis.

  20. Application of a novel microtitre plate-based assay for the discovery of new inhibitors of DNA gyrase and DNA topoisomerase VI.

    Science.gov (United States)

    Taylor, James A; Mitchenall, Lesley A; Rejzek, Martin; Field, Robert A; Maxwell, Anthony

    2013-01-01

    DNA topoisomerases are highly exploited targets for antimicrobial drugs. The spread of antibiotic resistance represents a significant threat to public health and necessitates the discovery of inhibitors that target topoisomerases in novel ways. However, the traditional assays for topoisomerase activity are not suitable for the high-throughput approaches necessary for drug discovery. In this study we validate a novel assay for screening topoisomerase inhibitors. A library of 960 compounds was screened against Escherichia coli DNA gyrase and archaeal Methanosarcina mazei DNA topoisomerase VI. Several novel inhibitors were identified for both enzymes, and subsequently characterised in vitro and in vivo. Inhibitors from the M. mazei topoisomerase VI screen were tested for their ability to inhibit Arabidopsis topoisomerase VI in planta. The data from this work present new options for antibiotic drug discovery and provide insight into the mechanism of topoisomerase VI.

  1. Nitrate Enhanced Microbial Cr(VI) Reduction-Final Report

    Energy Technology Data Exchange (ETDEWEB)

    John F. Stolz

    2011-06-15

    A major challenge for the bioremediation of radionuclides (i.e., uranium, technetium) and metals (i.e., Cr(VI), Hg) is the co-occurrence of nitrate as it can inhibit metal transformation. Denitrification (nitrate reduction to dinitrogen gas) is considered the most important ecological process. For many metal and metalloid reducing bacteria, however, ammonia is the end product through respiratory nitrate reduction (RNRA). The focus of this work was to determine how RNRA impacts Cr(VI) transformation. The goal was to elucidate the specific mechanism(s) that limits Cr(VI) reduction in the presence of nitrate and to use this information to develop strategies that enhance Cr(VI) reduction (and thus detoxification). Our central hypothesis is that nitrate impacts the biotransformation of metals and metalloids in three ways 1) as a competitive alternative electron acceptor (inhibiting transformation), 2) as a co-metabolite (i.e., concomitant reduction, stimulating transformation), and 3) as an inducer of specific proteins and pathways involved in oxidation/reduction reactions (stimulating transformation). We have identified three model organisms, Geobacter metallireducens (mechanism 1), Sulfurospirillum barnesii, (mechasism 2), and Desulfovibrio desulfuricans (mechanisms 3). Our specific aims were to 1) investigate the role of Cr(VI) concentration on the kinetics of both growth and reduction of nitrate, nitrite, and Cr(VI) in these three organisms; 2) develop a profile of bacterial enzymes involved in nitrate transformation (e.g., oxidoreductases) using a proteomic approach; 3) investigate the function of periplasmic nitrite reductase (Nrf) as a chromate reductase; and 4) develop a strategy to maximize microbial chromium reduction in the presence of nitrate. We found that growth on nitrate by G. metallireducens was inhibited by Cr(VI). Over 240 proteins were identified by LC/MS-MS. Redox active proteins, outer membrane heavy metal efflux proteins, and chemotaxis sensory

  2. Adsorption characteristics of U(VI) on Fe(III)Cr(III) (oxy)hydroxides synthesized at different temperatures.

    Science.gov (United States)

    Ahn, Hyangsig; Jo, Ho Young; Lee, Young Jae; Kim, Geon-Young

    2016-07-01

    In this study, the adsorption behavior of U(VI) on (oxy)hydroxides synthesized at different temperatures (25 and 75 °C) was investigated. Four (oxy)hydroxides were synthesized by drying slurries of Fe(III) and Fe(III)Cr(III) (oxy)hydroxide in a vacuum desiccator (25 °C) or in an oven (75 °C). Batch adsorption tests were conducted using the (oxy)hydroxides thus synthesized and groundwater containing uranium ions. In general, the U(VI) removal fraction significantly increased with increasing pH from 3 to 5, remained constant with increasing pH from 5 to 9, and decreased at pH greater than 9, regardless of the type of (oxy)hydroxides and solid-to-liquid ratio. The effect of pH on the U(VI) removal fraction was more significant at a low solid-to-liquid ratio. The oven-dried Fe(III) (oxy)hydroxide exhibited a U(VI) removal fraction lower than that of the vacuum-dried one, whereas the oven-dried Fe(III)Cr(III) (oxy)hydroxide exhibited a U(VI) removal fraction higher than that exhibited by the vacuum-dried one. X-ray photoelectron spectroscopy (XPS) analysis results indicated that the difference in the U(VI) removal fraction is attributed to the dissolution and precipitation of the Fe(III) (oxy)hydroxide during oven drying and dehydration of the Fe(III)Cr(III) (oxy)hydroxide during oven drying.

  3. Serological response following re-vaccination with Salmonella typhi Vi-capsular polysaccharide vaccines in healthy adult travellers.

    Science.gov (United States)

    Roggelin, Louise; Vinnemeier, Christof D; Fischer-Herr, Johanna; Johnson-Weaver, Brandi T; Rolling, Thierry; Burchard, Gerd D; Staats, Herman F; Cramer, Jakob P

    2015-08-01

    An injectable Vi-capsular polysaccharide vaccine against typhoid fever is available but vaccine-induced immunity tends to wane over time. The phenomenon of immunotolerance or hyporesponsiveness has earlier been described for polysaccharide vaccines such as pneumococcal capsular polysaccharide vaccine and some publications also suggest a possible immunotolerance after revaccination with Vi-capsular polysaccharide vaccines. In this study, post-immunisation antibody concentrations in adult travellers first vaccinated with a Salmonella typhi Vi-capsular polysaccharide vaccine (primary vaccination group) were compared with those having received one or more vaccinations previously (multiple vaccinations group). Vaccines administered were Typherix(®) (GlaxoSmithKline), Typhim Vi(®) (Sanofi Pasteur MSD) or Hepatyrix(®) (GlaxoSmithKline). Blood samples were obtained prior to vaccination (day 0) and on day 28 (-1/+14) after vaccination. Serum Vi-Antigen IgG concentrations were measured by ELISA. Of the 85 subjects included in the per protocol data set, 45 (53%) belonged to the multiple vaccinations group. In both groups, geometric mean antibody concentrations (GMCs) were significantly higher after vaccination than before vaccination. Pre-vaccination GMCs were lower in the primary vaccination group than in the multiple vaccinations group (3.40 μg/ml versus 6.13 μg/ml, P=0.005), while there was no significant difference in the post vaccination GMCs between groups (11.34 μg/ml versus 14.58 μg/ml, P=0.4). In the multiple vaccinations group, vaccination was performed 18 to 57 months after the last vaccination (median 38 months) and there was a negative correlation between time since last vaccination and antibody concentration on day 0. In conclusion, we were not able to demonstrate a relevant immunotolerance after multiple versus primary vaccination with S. typhi Vi-capsular polysaccharide vaccines.

  4. Effects of chromium(III and VI) on spring barley and maize biomass yield and content of nitrogenous compounds.

    Science.gov (United States)

    Wyszkowski, Mirosław; Radziemska, Maja

    2010-01-01

    The aim of this study was to (1) determine the effects of trivalent Cr(III) or hexavalent chromium Cr(VI) soil contamination on biomass yield and nitrogenous compound content of spring barley (Hordeum vulgare L.) as the main crop and subsequently maize (Zea mays L.) grown successively, and (2) examine whether the neutralizing additives applied (compost, zeolite, and calcium oxide) may be effective in reducing adverse impact of chromium (Cr) on crops. Spring barley yield was markedly decreased by Cr compounds, particularly Cr(VI). In contrast, maize yield was significantly increased by Cr(VI). Hexavalent Cr exerted a greater effect than the Cr(III) form on nitrogen levels in spring barley. Chromium significantly increased ammonia nitrogen content in maize. The accumulation of NO(3)(-)-N in plants treated with Cr(VI) was lower than in controls. The application of compost, zeolite, and calcium oxide onto the soil increased yield of maize only in pots containing Cr(III). Neutralizing additives exerted a positive, increased effect on the N-total content of maize but not spring barley, which was apparent with calcium oxide. Accumulation of NH(4)(+)-N in maize in pots with Cr(VI) was increased by all additives applied. The content of nitrate nitrogen in spring barley was predominantly affected by addition of compost and calcium oxide into the soil, producing a significant rise in NO(3)(-)-N content. Chromium, especially Cr(VI), used at doses of 100 and 150 mg/kg soil exerted adverse effects in treated plants, particularly spring barley.

  5. Amberlite XAD-4 functionalized with succinic acid for the solid phase extractive preconcentration and separation of uranium(VI).

    Science.gov (United States)

    Metilda, P; Sanghamitra, K; Mary Gladis, J; Naidu, G R K; Prasada Rao, T

    2005-01-15

    Amberlite XAD-4 resin has been functionalized with succinic acid by coupling it with dibromosuccinic acid after acetylation. The resulting resin has been characterized by FT-IR, elemental analysis and TG