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Sample records for chromated copper arsenate

  1. ASSESSING CHILDREN'S EXPOSURES TO THE WOOD PRESERVATIVE CCA (CHROMATED COPPER ARSENATE) ON TREATED PLAYSETS AND DECKS

    Science.gov (United States)

    Concerns have been raised regarding the safety of young children contacting arsenic and chromium residues while playing on and around Chromated Copper Arsenate (CCA) treated wood playground structures and decks. Although CCA registrants voluntarily canceled treated wood for re...

  2. Oxalic acid as an assisting agent for the electrodialytic remediation of chromated copper arsenate treated timber waste

    DEFF Research Database (Denmark)

    Ribeiro, Alexandra B.; Mateus, Eduardo P.; Ottosen, Lisbeth M.

    1999-01-01

    The electrodialytic process is proposed as a technique for the remediation of chromated copper arsenate treated timber waste, using oxalic acid as assisting agent. The method prowed succesfull 93% Cu, 95% Cr and 99% As was removed from the timber.......The electrodialytic process is proposed as a technique for the remediation of chromated copper arsenate treated timber waste, using oxalic acid as assisting agent. The method prowed succesfull 93% Cu, 95% Cr and 99% As was removed from the timber....

  3. Arsenic and Chromium Partitioning in a Podzolic Soil Contaminated by Chromated Copper Arsenate

    Energy Technology Data Exchange (ETDEWEB)

    Hopp, L.; Nico, P.S.; Marcus, M.A.; Peiffer, S. (Bayreuth); (LBNL)

    2008-10-14

    This research combined the use of selective extractions and X-ray spectroscopy to examine the fate of As and Cr in a podzolic soil contaminated by chromated copper arsenate (CCA). Iron was enriched in the upper 30 cm due to a previous one-time treatment of the soil with Fe(II). High oxalate-soluble Al concentrations in the Bs horizon of the soil and micro-XRD data indicated the presence of short-range ordered aluminosilicates (i.e., proto-imogolite allophane, PIA). In the surface layers, Cr, as Cr(III), was partitioned between a mixed Fe(III)/Cr(III) solid phase that formed upon the Fe(II) application (25--50%) and a recalcitrant phase (50--75%) likely consisting of organic material such as residual CCA-treated wood. Deeper in the profile Cr appeared to be largely in the form of extractable (hydr)oxides. Throughout the soil, As was present as As(V). In the surface layers a considerable fraction of As was also associated with a recalcitrant phase, probably CCA-treated woody debris, and the remainder was associated with (hydr)oxide-like solid phases. In the Bs horizon, however, XAS and XRF findings strongly pointed to the presence of PIA acting as an effective adsorbent for As. This research shows for the first time the relevance of PIA for the adsorption of As in natural soils.

  4. Arsenic and chromium partitioning in a podzolic soil contaminated by chromated copper arsenate

    Energy Technology Data Exchange (ETDEWEB)

    Nico, Peter; Hopp, Luisa; Nico, Peter S.; Marcus, Matthew A.; Peiffer, Stefan

    2008-06-01

    This research combined the use of selective extractions and x-ray spectroscopy to examine the fate of As and Cr in a podzolic soil contaminated by chromated copper arsenate (CCA). Iron was enriched in the upper 30 cm due to a previous one-time treatment of the soil with Fe(II). High oxalate-soluble Al concentrations in the Bs horizon of the soil and micro-XRD data indicated the presence of short-range ordered aluminosilicates (i.e. proto-imogolite allophane, PIA). In the surface layers, Cr, as Cr(III), was partitioned between a mixed Fe(III)/Cr(III) solid phase that formed upon the Fe(II) application (25-50%) and a recalcitrant phase (50-75%) likely consisting of organic material such as residual CCA-treated wood. Deeper in the profile Cr appeared to be largely in the form of extractable (hydr)oxides. Throughout the soil, As was present as As(V). In the surface layers a considerable fraction of As was also associated with a recalcitrant phase, probably CCA-treated woody debris, and the remainder was associated with (hydr)oxide-like solid phases. In the Bs horizon, however, XAS and XRF findings strongly pointed to the presence of PIA acting as an effective adsorbent for As. This research shows for the first time the relevance of PIA for the adsorption of As in natural soils.

  5. Determination of chromated copper arsenate (CCA) in treated wood of Eucalyptus

    Energy Technology Data Exchange (ETDEWEB)

    Parreira, Paulo S., E-mail: parreira@uel.b [Universidade Estadual de Londrina (UEL), PR (Brazil). Dept. de Fisica. Lab.de Fisica Nuclear Aplicada; Vendrametto, Guilherme R.; Cunha, Magda E.T., E-mail: grvendrametto@gmail.co [Universidade Norte do Parana, Arapongas, PR (Brazil). Centro de Ciencias Humanas, da Saude, Exatas e Tecnologicas-A

    2009-07-01

    This work deals with the possible application of a portable energy dispersive handmade system (PXRF-LFNA-02) for the determination of Chromium, Copper and Arsenic in the preservative solution used to protect commercial wood of Eucalyptus, which are employed as wood fence, posts, contention fences, railroad sleepers, etc. It was prepared five body-of-proof made of eucalyptus alburnum with different concentrations for each element varying from 0.0061 to 0.0180 (g/g) for CrO{sub 3}, 0.0024 to 0.0070 (g/g) for CuO and 0.0044 to 0.0129 (g/g) for As{sub 2}O{sub 5}. Four of them were used for calibration curves and one used as reference sample. It was used a commercial CCA (Chromated Copper Arsenate ) solution to prepare the samples. The results show a good linear regression between concentrations and X-rays intensities, after applied the multiple linear regression methodology for interelemental corrections. The values obtained with this methodology were 3.01(kg/m{sup 3}), 1.18 (kg/m{sup 3}) e 2.21 (kg/m{sup 3}) for CrO{sub 3}, CuO and As{sub 2}O{sub 5}, respectively, while the nominal values are 2.90 (kg/m{sup 3}) for CrO{sub 3}, 1.13 (kg/m{sup 3}) for CuO and 2.07 (kg/m{sup 3}) for As{sub 2}O{sub 5}. The ED-XRF (Energy Dispersive X-Rays Fluorescence) is a well established technique with high-speed of analytical procedure and its portable configuration allowing a multielemental, simultaneous and non destructive analyses besides in situ application. (author)

  6. Chemical-specific health consultation for chromated copper arsenate chemical mixture: port of Djibouti.

    Science.gov (United States)

    Chou, Selene; Colman, Joan; Tylenda, Carolyn; De Rosa, Christopher

    2007-05-01

    The Agency for Toxic Substances and Disease Registry (ATSDR) prepared this health consultation to provide support for assessing the public health implications of hazardous chemical exposure, primarily through drinking water, related to releases of chromated copper arsenate (CCA) in the port of Djibouti. CCA from a shipment, apparently intended for treating electric poles, is leaking into the soil in the port area. CCA is a pesticide used to protect wood against decay-causing organisms. This mixture commonly contains chromium(VI) (hexavalent chromium) as chromic acid, arsenic(V) (pentavalent arsenic) as arsenic pentoxide and copper (II) (divalent copper) as cupric oxide, often in an aqueous solution or concentrate. Experimental studies of the fate of CCA in soil and monitoring studies of wood-preserving sites where CCA was spilled on the soil indicate that the chromium(VI), arsenic and copper components of CCA can leach from soil into groundwater and surface water. In addition, at CCA wood-preserving sites, substantial concentrations of chromium(VI), arsenic and copper remained in the soil and were leachable into water four years after the use of CCA was discontinued, suggesting prolonged persistence in soil, with continued potential for leaching. The degree of leaching depended on soil composition and the extent of soil contamination with CCA. In general, leaching was highest for chromium(VI), intermediate for arsenic and lowest for copper. Thus, the potential for contamination of sources of drinking water exists. Although arsenic that is leached from CCA-contaminated soil into surface water may accumulate in the tissues of fish and shellfish, most of the arsenic in these animals will be in a form (often called fish arsenic) that is less harmful. Copper, which leaches less readily than the other components, can accumulate in tissues of mussels and oysters. Chromium is not likely to accumulate in the tissues of fish and shellfish. Limited studies of air

  7. Evaluating the potential for environmental pollution from chromated copper arsenate (CCA)-treated wood waste: a new mass balance approach.

    Science.gov (United States)

    Mercer, T G; Frostick, L E

    2014-07-15

    The potential for pollution from arsenic, chromium and copper in chromated copper arsenate (CCA) treated wood waste was assessed using two lysimeter studies. The first utilised lysimeters containing soil and CCA wood waste mulch exposed to natural conditions over a five month period. The second study used the same lysimeter setup in a regulated greenhouse setting with a manual watering regime. Woodchip, soil and leachate samples were evaluated for arsenic, chromium and copper concentrations. Resultant concentration data were used to produce mass balances, an approach thus far unused in such studies. This novel analysis revealed new patterns of mobility and distribution of the elements in the system. The results suggest that CCA wood waste tends to leach on initial exposure to a leachant and during weathering of the wood. When in contact with soil, metal(loid) transport is reduced due to complexation reactions. With higher water application or where the adsorption capacity of the soil is exceeded, the metal(loid)s are transported through the soil column as leachate. Overall, there was an unexplained loss of metal(loid)s from the system that might be attributed to volatilisation of arsenic and plant uptake. This suggests a hitherto unidentified risk to both the environment and human health. PMID:24858049

  8. Exergy analysis of the Chartherm process for energy valorization and material recuperation of chromated copper arsenate (CCA) treated wood waste.

    Science.gov (United States)

    Bosmans, A; Auweele, M Vanden; Govaerts, J; Helsen, L

    2011-04-01

    The Chartherm process (Thermya, Bordeaux, France) is a thermochemical conversion process to treat chromated copper arsenate (CCA) impregnated wood waste. The process aims at maximum energy valorization and material recuperation by combining the principles of low-temperature slow pyrolysis and distillation in a smart way. The main objective of the exergy analysis presented in this paper is to find the critical points in the Chartherm process where it is necessary to apply some measures in order to reduce exergy consumption and to make energy use more economic and efficient. It is found that the process efficiency can be increased with 2.3-4.2% by using the heat lost by the reactor, implementing a combined heat and power (CHP) system, or recuperating the waste heat from the exhaust gases to preheat the product gas. Furthermore, a comparison between the exergetic performances of a 'chartherisation' reactor and an idealized gasification reactor shows that both reactors destroy about the same amount of exergy (i.e. 3500kWkg(wood)(-1)) during thermochemical conversion of CCA-treated wood. However, the Chartherm process possesses additional capabilities with respect to arsenic and tar treatment, as well as the extra benefit of recuperating materials.

  9. CHROMATED COPPER ARSENATE (CCA TREATED WOOD: DESTINATION OPTIONS FOR WASTES GENERATED AND PERSPECTIVES IN THE DEVELOPMENT OF METHODOLOGIES FOR TOXIC ELEMENTS REMOVAL

    Directory of Open Access Journals (Sweden)

    PIRES, Marçal

    2015-01-01

    Full Text Available The wood has been used for various functions, one of them is the manufacture of poles for electrification and telephony. However, this material has a big propensity to deteriorate. To increase its durability, some alternatives are employed, one of them is the incorporation of toxic substances (preservatives to protect the wood from agents such as fungi, bacteria and xylophagous insects that cause its decay. Currently, the preservative chromated copper arsenate (CCA is the most widely used for this purpose. However, when the CCA treated wood poles reach the end of their useful life, they become hazardous waste due to the presence of chromium and arsenic. In this work are presented the main methodologies for treatment, destination options and adequate disposal of these wastes, as well as different methods for toxic elements removal from the CCA-treated wood

  10. Accumulation of copper, chromium, and arsenic in blue mussels (Mytilus edulis) from laboratory and field exposures to wood treated with chromated copper arsenate type C

    Energy Technology Data Exchange (ETDEWEB)

    Adler-Ivanbrook, L.; Breslin, V.T. [State Univ. of New York, Stony Brook, NY (United States)

    1999-02-01

    Laboratory and field experiments were conducted to examine the uptake of Cu, Cr, and As leached from southern yellow pine (SYP) treated with chromated copper arsenate type C (CCA-C), as well as effects on mortality and growth, in blue mussels (Mytilus edulis). Mussels were exposed to CCA-C-treated wood at a preservative retention of 40 kg/m{sup 3} and control (nontreated) SYP in laboratory flow-through sea table and field exposure experiments for 9 months in 1994 and 3 months in 1995. Mussels were sampled at regular intervals to evaluate possible short- and long-term exposure effects., Individual mussels were measured to determine the length, dry weight, and condition index. Mussel tissues were than analyzed for Cu, Cr, and As. Results showed few significant differences in condition index, dry weight, and length between CCA-C-exposed and control mussels. In addition, no statistically significant differences in mortality were found between the mussels exposed to CCA-C-treated and nontreated SYP in the laboratory flow-through sea table and field exposure experiments. Significant differences in Cu, As, and Cr contents in mussel tissues between treatments were few, and generally cannot be attributed to exposure to CCA-C-treated SYP. The lack of Cu, Cr, and As uptake from CCA-C-treated SYP was attributed to the low, although continuous, rate of release of these elements from CCA-C-treated wood and to the experimental design, which allowed continuous flushing, prohibiting the accumulation of these elements in the water surrounding the mussels.

  11. Classification of waste wood treated with chromated copper arsenate and boron/fluorine preservatives; Classificacao de residuos de madeira tratada com preservativos a base de arseniato de cobre cromatado e de boro/fluor

    Energy Technology Data Exchange (ETDEWEB)

    Ferrarini, Suzana Frighetto; Santos, Heldiane Souza dos; Miranda, Luciana Gampert; Azevedo, Carla M.N.; Pires, Marcal J.R., E-mail: suzana.ferrarini@gmail.com [Faculdade de Quimica, Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre, RS (Brazil); Maia, Sandra Maria [Instituto de Quimica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil)

    2012-07-01

    Classification of waste wood treated with chromated copper arsenate (CCA) and boron/fluorine preservatives, according to NBR 10004, was investigated. The leaching test (ABNT NBR 10005) for As and Cr, and solubilization test (ABNT NBR 10006) for F, were applied to out-of-service wooden poles. Concentrations of As and Cr in leachates were determined by ICP-MS and of F by ESI. Values for As were higher than 1 mg L{sup -1} classifying the waste as hazardous material (Class I) whereas values for F (> 1.5 mg L{sup -1}) were non-hazardous but indicated non-inert material (Class IIA). (author)

  12. Removal of toxic ions (chromate, arsenate, and perchlorate) using reverse osmosis, nanofiltration, and ultrafiltration membranes

    KAUST Repository

    Yoon, Jaekyung

    2009-09-01

    Rejection characteristics of chromate, arsenate, and perchlorate were examined for one reverse osmosis (RO, LFC-1), two nanofiltration (NF, ESNA, and MX07), and one ultrafiltration (UF and GM) membranes that are commercially available. A bench-scale cross-flow flat-sheet filtration system was employed to determine the toxic ion rejection and the membrane flux. Both model and natural waters were used to prepare chromate, arsenate, and perchlorate solutions (approximately 100 μg L-1 for each anion) in mixtures in the presence of other salts (KCl, K2SO4, and CaCl2); and at varying pH conditions (4, 6, 8, and 10) and solution conductivities (30, 60, and 115 mS m-1). The rejection of target ions by the membranes increases with increasing solution pH due to the increasingly negative membrane charge with synthetic model waters. Cr(VI), As(V), and ClO4 - rejection follows the order LFC-1 (>90%) > MX07 (25-95%) ≅ ESNA (30-90%) > GM (3-47%) at all pH conditions. In contrast, the rejection of target ions by the membranes decreases with increasing solution conductivity due to the decreasingly negative membrane charge. Cr(VI), As(V), and ClO4 - rejection follows the order CaCl2 < KCl ≅ K2SO4 at constant pH and conductivity conditions for the NF and UF membranes tested. For natural waters the LFC-1 RO membrane with a small pore size (0.34 nm) had a significantly greater rejection for those target anions (>90%) excluding NO3 - (71-74%) than the ESNA NF membrane (11-56%) with a relatively large pore size (0.44 nm), indicating that size exclusion is at least partially responsible for the rejection. The ratio of solute radius (ri,s) to effective membrane pore radius (rp) was employed to compare ion rejection. For all of the ions, the rejection is higher than 70% when the ri,s/rp ratio is greater than 0.4 for the LFC-1 membrane, while for di-valent ions (CrO4 2 -, SO4 2 -, and HAsSO4 2 -) the rejection (38-56%) is fairly proportional to the ri,s/rp ratio (0.32-0.62) for the ESNA

  13. Effects of arsenate, chromate, and sulfate on arsenic and chromium uptake and translocation by arsenic hyperaccumulator Pteris vittata L.

    Science.gov (United States)

    de Oliveira, Letúzia Maria; Ma, Lena Q; Santos, Jorge A G; Guilherme, Luiz R G; Lessl, Jason T

    2014-01-01

    We investigated effects of arsenate (AsV), chromate (CrVI) and sulfate on As and Cr uptake and translocation by arsenic hyperaccumulator Pteris vittata (PV), which was exposed to AsV, CrVI and sulfate at 0, 0.05, 0.25 or 1.25 mM for 2-wk in hydroponic system. PV was effective in accumulating large amounts of As (4598 and 1160 mg/kg in the fronds and roots at 0.05 mM AsV) and Cr (234 and 12,630 mg/kg in the fronds and roots at 0.05 mM CrVI). However, when co-present, AsV and CrVI acted as inhibitors, negatively impacting their accumulation in PV. Arsenic accumulation in the fronds was reduced by 92% and Cr by 26%, indicating reduced As and Cr translocation. However, addition of sulfate increased uptake and translocation of As by 26-28% and Cr by 1.63 fold. This experiment demonstrated that As and Cr inhibited each other in uptake and translocation by PV but sulfate enhanced As and Cr uptake and translocation by PV.

  14. Chromatic annuli formation and sample oxidation on copper thin films by femtosecond laser.

    Science.gov (United States)

    He, Shutong; Amoruso, Salvatore; Pang, Dongqing; Wang, Chingyue; Hu, Minglie

    2016-04-28

    We report an experimental investigation on the irradiation of copper thin films with high repetition rate femtosecond laser pulses (1040 nm, 50 MHz), in ambient air and liquid water. We observe a novel, striking phenomenon of chromatic copper oxides (CuO and Cu2O) annuli generation. The characteristic features of the chromatic copper oxide annuli are studied by exploiting micro-Raman spectroscopy, optical and scanning electron microscopies. In the case of irradiation in water, the seldom investigated effects of the immersion time, tw, after irradiation with a fixed number of pulses are analyzed, and an intriguing dependence of the color of the chromatic annuli on tw is observed. This remarkable behavior is explained by proposing an interpretation scenario addressing the various processes involved in the process. Our experimental findings show that Cu2O nanoparticles (size of ≈20 nm) and Cu2O nanocubes (nanocube edges of ≈30, ≈60 nm) can be effectively generated by exploiting high repetition rate laser-assisted oxidation. PMID:27131559

  15. Chromatic annuli formation and sample oxidation on copper thin films by femtosecond laser

    Science.gov (United States)

    He, Shutong; Amoruso, Salvatore; Pang, Dongqing; Wang, Chingyue; Hu, Minglie

    2016-04-01

    We report an experimental investigation on the irradiation of copper thin films with high repetition rate femtosecond laser pulses (1040 nm, 50 MHz), in ambient air and liquid water. We observe a novel, striking phenomenon of chromatic copper oxides (CuO and Cu2O) annuli generation. The characteristic features of the chromatic copper oxide annuli are studied by exploiting micro-Raman spectroscopy, optical and scanning electron microscopies. In the case of irradiation in water, the seldom investigated effects of the immersion time, tw, after irradiation with a fixed number of pulses are analyzed, and an intriguing dependence of the color of the chromatic annuli on tw is observed. This remarkable behavior is explained by proposing an interpretation scenario addressing the various processes involved in the process. Our experimental findings show that Cu2O nanoparticles (size of ≈20 nm) and Cu2O nanocubes (nanocube edges of ≈30, ≈60 nm) can be effectively generated by exploiting high repetition rate laser-assisted oxidation.

  16. Towards a selective adsorbent for arsenate and selenite in the presence of phosphate: Assessment of adsorption efficiency, mechanism, and binary separation factors of the chitosan-copper complex.

    Science.gov (United States)

    Yamani, Jamila S; Lounsbury, Amanda W; Zimmerman, Julie B

    2016-01-01

    The potential for a chitosan-copper polymer complex to select for the target contaminants in the presence of their respective competitive ions was evaluated by synthesizing chitosan-copper beads (CCB) for the treatment of (arsenate:phosphate), (selenite:phosphate), and (selenate:sulfate). Based on work by Rhazi et al., copper (II) binds to the amine moiety on the chitosan backbone as a monodentate complex (Type I) and as a bidentate complex crosslinking two polymer chains (Type II), depending on pH and copper loading. In general, the Type I complex exists alone; however, beyond threshold conditions of pH 5.5 during synthesis and a copper loading of 0.25 mol Cu(II)/mol chitosan monomer, the Type I and Type II complexes coexist. Subsequent chelation of this chitosan-copper ligand to oxyanions results in enhanced and selective adsorption of the target contaminants in complex matrices with high background ion concentrations. With differing affinities for arsenate, selenite, and phosphate, the Type I complex favors phosphate chelation while the Type II complex favors arsenate chelation due to electrostatic considerations and selenite chelation due to steric effects. No trend was exhibited for the selenate:sulfate system possibly due to the high Ksp of the corresponding copper salts. Binary separation factors, α12, were calculated for the arsenate-phosphate and selenite-phosphate systems, supporting the mechanistic hypothesis. While, further research is needed to develop a synthesis method for the independent formation of the Type II complexes to select for target contaminants in complex matrices, this work can provide initial steps in the development of a selective adsorbent.

  17. EVALUATION OF THE EFFECTIVENESS OF COATINGS IN REDUCING DISLODGEABLE ARSENIC, CHROMIUM, AND COPPER FROM CCA TREATED WOOD; FINAL REPORT

    Science.gov (United States)

    EPA conducted a study to evaluate the effect of coatings on dislodgeable arsenic, chromium, and copper residues on the surfaces of chromated copper arsenate (CAA) treated wood. Dislodgeable CCA, determined by wipe sampling the wood surfaces, was the primary evaluation criterion f...

  18. EVALUATION OF THE EFFECTIVENESS OF COATINGS IN REDUCING DISLODGEABLE ARSENIC, CHROMIUM, AND COPPER FROM CCA-TREATED WOOD

    Science.gov (United States)

    This is a 2 year study designed to evaluate the effectiveness of a variety of deck sealants in reducing or eliminating potential exposure to arsenic, chromium, and copper from chromated copper arsenate-treated wood used in residential settings, like decks and playsets.

  19. EMISSIONS OF CHROMIUM, COPPER, ARSENIC AND PCDDS/FS FROM OPEN BURNING OF CCA TREATED WOOD

    Science.gov (United States)

    Aged and weathered chromated copper arsenate (CCA) treated wood was burned in an open burn research facility to characterize the air emissions and residual bottom ash. In addition to continuous measurements of gases and temperature, samples were collected to characterize the emis...

  20. BIOAVAILABILITY OF ARSENIC, CHROMIUM, AND COPPER FROM CCA CONTAMINATED SOILS AND DUSTS

    Science.gov (United States)

    It is estimated that 70% of single family homes have pressure-treated wood decks or porches and 14% of playground equipment uses pressure-treated wood. This popular form of wood contains chromated copper arsenate (CCA), which is an antimicrobial pesticide and is currently underg...

  1. BIOAVAILABILITY OF ARSENIC, CHROMIUM, AND COPPER FOR CCA CONTAMINATED SOILS AND DUST

    Science.gov (United States)

    It is estimated that 70% of single family homes have pressure-treated wood decks or porches and 14% of playground equipment uses pressure-treated wood. This popular form of wood contains chromated copper arsenate (CCA), which is an antimicrobial pesticide and is currently underg...

  2. Evaluation of the toxic effects of arsenite, chromate, cadmium, and copper using a battery of four bioassays

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Kyung-Seok; Lee, Pyeong-Koo [Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon (Korea, Republic of). Geologic Environment Div.; Kong, In Chul [Yeungnam Univ., Kyungbuk (Korea, Republic of). Dept. of Environmental Engineering

    2012-09-15

    The sensitivities of four different kinds of bioassays to the toxicities of arsenite, chromate, cadmium, and copper were compared. The different bioassays exhibited different sensitivities, i.e., they responded to different levels of toxicity of each of the different metals. However, with the exception of the {alpha}-glucosidase enzyme activity, arsenite was the most toxic compound towards all the tested organisms, exhibiting the highest toxic effect on the seeds of Lactuca, with an EC{sub 50} value of 0.63 mg/L. The sensitivities of Lactuca and Raphanus were greater than the sensitivities of two other kinds of seeds tested. Therefore, these were the seeds appropriate for use in a seed germination assay. A high revertant mutagenic ratio (5:1) of Salmonella typhimurium was observed with an arsenite concentration of 0.1 {mu}g/plate, indicative of a high possibility of mutagenicity. These different results suggested that a battery of bioassays, rather than one bioassay alone, is needed as a more accurate and better tool for the bioassessment of environmental pollutants. (orig.)

  3. "Artifactual" arsenate DNA

    DEFF Research Database (Denmark)

    Nielsen, Peter E

    2012-01-01

    The recent claim by Wolfe-Simon et al. that the Halomonas bacterial strain GFAJ-1 when grown in arsenate-containing medium with limiting phosphate is able to substitute phosphate with arsenate in biomolecules including nucleic acids and in particular DNA(1) arose much skepticism, primarily due...... to the very limited chemical stability of arsenate esters (see ref. 2 and references therein). A major part of the criticisms was concerned with the insufficient (bio)chemical evidence in the Wolfe-Simon study for the actual chemical incorporation of arsenate in DNA (and/or RNA). Redfield et al. now present...... evidence that the identification of arsenate DNA was artifactual....

  4. Natural Arsenate DNA?

    DEFF Research Database (Denmark)

    Nielsen, Peter E

    2011-01-01

    The recent paper by Wolfe-Simon et al.1 reporting a bacterial strain, which is able to grow in high concentrations of arsenate, apparently in the absence of phosphate, and claims that in this strain arsenate is substituting for phosphate, e.g. in nucleic acids (Figure 1), was highly profiled, att...

  5. “Artifactual” arsenate DNA

    OpenAIRE

    Nielsen, Peter E.

    2012-01-01

    The recent claim by Wolfe-Simon et al. that the Halomonas bacterial strain GFAJ-1 when grown in arsenate-containing medium with limiting phosphate is able to substitute phosphate with arsenate in biomolecules including nucleic acids and in particular DNA 1 arose much skepticism, primarily due to the very limited chemical stability of arsenate esters (see ref. 2 and references therein). A major part of the criticisms was concerned with the insufficient (bio)chemical evidence in the Wolfe-Simon...

  6. Lung retention and bioavailability of arsenic after single intratracheal administration of sodium arsenite, sodium arsenate, fly ash and copper smelter dust in the hamster.

    Science.gov (United States)

    Buchet, J P; Lauwerys, R R; Yager, J W

    1995-12-01

    Arsenic is present in airborne particulate material released by coal-fired power plants and non-ferrous metal smelters. We have assessed whether the physico-chemical properties of arsenic in such particles play a role in its lung retention and uptake by the body. Female hamsters were given a single intratracheal instillation of fly ash or copper smelter dust suspensions (at doses of 50 or 100 μg As kg(-1)) or identical amounts of soluble tri- and pentavalent arsenic, in the presence or absence of an inert dust material (tungsten carbide). The concentration of the element was measured in a 24 hour urine sample collected on the 1st, 2nd and 6th day after treatment and arsenic remaining in lung tissue was determined at the end of the same time periods. Both lung retention and urinary As excretion indicate a prolonged contact of the lung tissue with particulate As in contrast to soluble As salts. In addition to the effect of solubility described here, more research is needed to determine the effect of particle size and lung loading on retention, as well as the potential differences in the lung inflammatory response using arsenic-rich particulates from various sources. PMID:24194290

  7. Application of a CCA-treated wood waste decontamination process to other copper-based preservative-treated wood after disposal

    Energy Technology Data Exchange (ETDEWEB)

    Janin, Amelie, E-mail: amelie.janin@ete.inrs.ca [University of Toronto, Faculty of Forestry, 33, Willcocks St., Toronto, ON, M5S 3B3 (Canada); Coudert, Lucie, E-mail: lucie.coudert@ete.inrs.ca [Institut national de la recherche scientifique (Centre Eau, Terre et Environnement), Universite du Quebec, 490 rue de la Couronne, Quebec, QC, G1K 9A9 (Canada); Riche, Pauline, E-mail: pauline.riche@ete.inrs.ca [Institut national de la recherche scientifique (Centre Eau, Terre et Environnement), Universite du Quebec, 490 rue de la Couronne, Quebec, QC, G1K 9A9 (Canada); Mercier, Guy, E-mail: guy_mercier@ete.inrs.ca [Institut national de la recherche scientifique (Centre Eau, Terre et Environnement), Universite du Quebec, 490 rue de la Couronne, Quebec, QC, G1K 9A9 (Canada); Cooper, Paul, E-mail: p.cooper@utoronto.ca [University of Toronto, Faculty of Forestry, 33, Willcocks St., Toronto, ON, M5S 3B3 (Canada); Blais, Jean-Francois, E-mail: blaisjf@ete.inrs.ca [Institut national de la recherche scientifique (Centre Eau, Terre et Environnement), Universite du Quebec, 490 rue de la Couronne, Quebec, QC, G1K 9A9 (Canada)

    2011-02-28

    Research highlights: {yields} This paper describes a process for the metal removal from treated (CA-, ACQ- or MCQ-) wood wastes. {yields} This sulfuric acid leaching process is simple and economic. {yields} The remediated wood could be recycled in the industry. - Abstract: Chromated copper arsenate (CCA)-treated wood was widely used until 2004 for residential and industrial applications. Since 2004, CCA was replaced by alternative copper preservatives such as alkaline copper quaternary (ACQ), copper azole (CA) and micronized copper quaternary (MCQ), for residential applications due to health concerns. Treated wood waste disposal is becoming an issue. Previous studies identified a chemical process for decontaminating CCA-treated wood waste based on sulfuric acid leaching. The potential application of this process to wood treated with the copper-based preservatives (alkaline copper quaternary (ACQ), copper azole (CA) and micronized copper quaternary (MCQ)) is investigated here. Three consecutive leaching steps with 0.1 M sulfuric acid at 75 deg, C for 2 h were successful for all the types of treated wood and achieved more than 98% copper solubilisation. The different acidic leachates produced were successively treated by coagulation using ferric chloride and precipitation (pH = 7) using sodium hydroxide. Between 94 and 99% of copper in leachates could be recovered by electrodeposition after 90 min using 2 A electrical current. Thus, the process previously developed for CCA-treated wood waste decontamination could be efficiently applied for CA-, ACQ- or MCQ-treated wood.

  8. 铬化砷酸铜防腐处理木材对环境安全的影响综述%The Evaluation of the Impact of Chromated Copper Arsenate Treated Wood on the Environmental Safety

    Institute of Scientific and Technical Information of China (English)

    于丽丽; 唐镇忠; 马晓军; 朱礼智

    2013-01-01

    对长期以来在木材防腐市场居于主导地位的铬化砷酸铜(CCA)处理木材对环境的影响进行了较为系统、全面的介绍,其中包括CCA防腐剂中铜、铬、砷等元素对环境的影响,以及CCA防腐处理木材使用过程中对环境的影响,旨在促进CCA处理木材的科学生产,保证CCA防腐处理木材的使用安全.

  9. Prokaryotic arsenate reductase enhances arsenate resistance in Mammalian cells.

    Science.gov (United States)

    Wu, Dan; Tao, Xuanyu; Wu, Gaofeng; Li, Xiangkai; Liu, Pu

    2014-01-01

    Arsenic is a well-known heavy metal toxicant in the environment. Bioremediation of heavy metals has been proposed as a low-cost and eco-friendly method. This article described some of recent patents on transgenic plants with enhanced heavy metal resistance. Further, to test whether genetic modification of mammalian cells could render higher arsenic resistance, a prokaryotic arsenic reductase gene arsC was transfected into human liver cancer cell HepG2. In the stably transfected cells, the expression level of arsC gene was determined by quantitative real-time PCR. Results showed that arsC was expressed in HepG2 cells and the expression was upregulated by 3 folds upon arsenate induction. To further test whether arsC has function in HepG2 cells, the viability of HepG2-pCI-ArsC cells exposed to arsenite or arsenate was compared to that of HepG2-pCI cells without arsC gene. The results indicated that arsC increased the viability of HepG2 cells by 25% in arsenate, but not in arsenite. And the test of reducing ability of stably transfected cells revealed that the concentration of accumulated trivalent arsenic increased by 25% in HepG2-pCI-ArsC cells. To determine the intracellular localization of ArsC, a fusion vector with fluorescent marker pEGFP-N1-ArsC was constructed and transfected into.HepG2. Laser confocal microscopy showed that EGFP-ArsC fusion protein was distributed throughout the cells. Taken together, these results demonstrated that prokaryotic arsenic resistant gene arsC integrated successfully into HepG2 genome and enhanced arsenate resistance of HepG2, which brought new insights of arsenic detoxification in mammalian cells.

  10. Cleaning of Chromate Manufacture Process

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Sodium chromate solubility is determined in the range of NaOH concentrations from 450 to 810 g/L and solution temperatures from 30 to 110 ℃. The optimized conditions to separate sodium chromate from NaOH in leached solution are resolved. It is first found the method to efficiently separate sodium chromate from NaOH and sodium aluminate in crude sodium chromate. Bench-scale studies on the separating are performed. Finally, good separation results are achieved.

  11. Chromatic polynomials for simplicial complexes

    DEFF Research Database (Denmark)

    Møller, Jesper Michael; Nord, Gesche

    2016-01-01

    In this note we consider s s -chromatic polynomials for finite simplicial complexes. When s=1 s=1 , the 1 1 -chromatic polynomial is just the usual graph chromatic polynomial of the 1 1 -skeleton. In general, the s s -chromatic polynomial depends on the s s -skeleton and its value at r r is the n...

  12. Embryotoxicity of arsenite and arsenate

    International Nuclear Information System (INIS)

    The distribution of 74As-labelled and arsenite in pregnant mice and a monkey has been studied by autoradiography and gamma counting of isolated tissues, and their in vitro toxicity to a chondrogenic system has been investigated. With both arsenic forms, given as single intravenous injections to the mother, the 74As-arsenic appeared to pass the mouse placenta relatively freely and approximately to the same extent. The retention time in material tissues including the placenta was, however, around three times longer with arsenite than with arsenate. In early gestation, high activity was registered in the embryonic neuroepithelium, which correlates well with reported CNS malformations in rodents. In late gestation, the distribution pattern was more like that in the adults. Accumulation in skin and squamous epithelia of the upper gastrointestinal tract (oral cavity, oesophagus and oesophageal region of stomach) dominated the distribution pucture, especially at a long survival interval. Arsenate, but not arsenite, showed affinity for the calcified areas of the skeleton. A marmoset monkey in late gestation receiving arsenite showed a somewhat lower rate of placental transfer than the mice. Skin and liver had the highest concentrations (at 8 hrs), both in mother and foetuses. This species is known not to methylate arsenic, resulting in stronger binding and longer retention times of arsenic as compared with other species. The stronger binding in maternal tissues may possibly explain the lower rate of placental transfer. Arsenite was shown to inhibit cartilage formation in a chick limb bud mesenchymal spot culture system (ED50 approximately 5-10μM) while arsenate seemed to be without effect at concentrations up to 200 μM (highest tested). Arsenate, however, showed a potential of the arsenite toxicity. (author)

  13. Absence of detectable arsenate in DNA from arsenate-grown GFAJ-1 cells

    OpenAIRE

    Reaves, Marshall Louis; Sinha, Sunita; Rabinowitz, Joshua D.; Kruglyak, Leonid; Redfield, Rosemary J.

    2012-01-01

    A strain of Halomonas bacteria, GFAJ-1, has been reported to be able to use arsenate as a nutrient when phosphate is limiting, and to specifically incorporate arsenic into its DNA in place of phosphorus. However, we have found that arsenate does not contribute to growth of GFAJ-1 when phosphate is limiting and that DNA purified from cells grown with limiting phosphate and abundant arsenate does not exhibit the spontaneous hydrolysis expected of arsenate ester bonds. Furthermore, mass spectrom...

  14. Assessment of zerovalent iron for stabilization of chromium, copper, and arsenic in soil

    Energy Technology Data Exchange (ETDEWEB)

    Kumpiene, Jurate [Division of Waste Science and Technology, Lulea University of Technology, Lulea SE-97187 (Sweden)]. E-mail: jurate.kumpiene@ltu.se; Ore, Solvita [Division of Waste Science and Technology, Lulea University of Technology, Lulea SE-97187 (Sweden); Renella, Giancarlo [Department of Soil Science and Plant Nutrition, University of Florence, P.le delle Cascine 28, Florence 50144 (Italy); Mench, Michel [UMR BIOGECO INRA 1202, Ecology of communities, Bordeaux 1 University, Bat. B8, RdC Est, Av. des Facultes, Talence F-33405 (France); Lagerkvist, Anders [Division of Waste Science and Technology, Lulea University of Technology, Lulea SE-97187 (Sweden); Maurice, Christian [Division of Waste Science and Technology, Lulea University of Technology, Lulea SE-97187 (Sweden)

    2006-11-15

    Stabilization of soil contaminated with trace elements is a remediation practice that does not reduce the total content of contaminants, but lowers the amounts of mobile and bioavailable fractions. This study evaluated the efficiency of Fe to reduce the mobility and bioavailability of Cr, Cu, As and Zn in a chromated copper arsenate (CCA)-contaminated soil using chemical, biochemical and biotoxicity tests. Contaminated soil was stabilized with 1% iron grit. This treatment decreased As and Cr concentrations in leachates (by 98% and 45%, respectively), in soil pore water (by 99% and 94%, respectively) and in plant shoots (by 84% and 95%, respectively). The stabilization technique also restored most of analyzed soil enzyme activities and reduced microbial toxicity, as evaluated by the BioTox{sup TM} test. After stabilization, exchangeable and bioaccessible fractions of Cu remained high, causing some residual toxicity in the treated soil. - Zerovalent iron effectively reduces mobility and bioavailability of As and Cr, but does not adequately stabilize Cu.

  15. Growth of strain SES-3 with arsenate and other diverse electron acceptors

    Science.gov (United States)

    Laverman, A.M.; Blum, J.S.; Schaefer, J.K.; Phillips, E.J.P.; Lovley, D.R.; Oremland, R.S.

    1995-01-01

    The selenate-respiring bacterial strain SES-3 was able to use a variety of inorganic electron acceptors to sustain growth. SES-3 grew with the reduction of arsenate to arsenite, Fe(III) to Fe(II), or thiosulfate to sulfide. It also grew in medium in which elemental sulfur, Mn(IV), nitrite, trimethylamine N-oxide, or fumarate was provided as an electron acceptor. Growth on oxygen was microaerophilic. There was no growth with arsenite or chromate. Washed suspensions of cells grown on selenate or nitrate had a constitutive ability to reduce arsenate but were unable to reduce arsenite. These results suggest that strain SES-3 may occupy a niche as an environmental opportunist by being able to take advantage of a diversity of electron acceptors.

  16. Field-scale leaching of arsenic, chromium and copper from weathered treated wood

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, A. Rasem, E-mail: hasan@arij.or [Department of Civil, Architectural and Environmental Engineering, University of Miami, 1251 Memorial Dr., Coral Gables, FL 33124 (United States); Hu Ligang [Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, University Park, Miami, FL 33199 (United States); Solo-Gabriele, Helena M., E-mail: hmsolo@miami.ed [Department of Civil, Architectural and Environmental Engineering, University of Miami, 1251 Memorial Dr., Coral Gables, FL 33124 (United States); Fieber, Lynne [Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149-1098 (United States); Cai Yong [Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, University Park, Miami, FL 33199 (United States); Southeast Environmental Research Center, Florida International University, 11200 SW 8th Street, University Park, Miami, FL 33199 (United States); Townsend, Timothy G. [Department of Environmental Engineering Sciences, University of Florida, 217 A.P. Black Hall, Gainesville, FL 32611-6450 (United States)

    2010-05-15

    Earlier studies documented the loss of wood preservatives from new wood. The objective of this study was to evaluate losses from weathered treated wood under field conditions by collecting rainfall leachate from 5 different wood types, all with a surface area of 0.21 m{sup 2}. Wood samples included weathered chromate copper arsenate (CCA) treated wood at low (2.7 kg/m{sup 3}), medium (4.8 kg/m{sup 3}) and high (35.4 kg/m{sup 3}) retention levels, new alkaline copper quat (ACQ) treated wood (1.1 kg/m{sup 3} as CuO) and new untreated wood. Arsenic was found to leach at a higher rate (100 mg in 1 year for low retention) than chromium and copper (<40 mg) in all CCA-treated wood samples. Copper leached at the highest rate from the ACQ sample (670 mg). Overall results suggest that metals' leaching is a continuous process driven by rainfall, and that the mechanism of release from the wood matrix changes as wood weathers. - Metals leaching rates on a percent basis increase as treated wood weathers, although the mass released decreases.

  17. Dissolution of Arsenic Minerals Mediated by Dissimilatory Arsenate Reducing Bacteria: Estimation of the Physiological Potential for Arsenic Mobilization

    Directory of Open Access Journals (Sweden)

    Drewniak Lukasz

    2014-01-01

    Full Text Available The aim of this study was characterization of the isolated dissimilatory arsenate reducing bacteria in the context of their potential for arsenic removal from primary arsenic minerals through reductive dissolution. Four strains, Shewanella sp. OM1, Pseudomonas sp. OM2, Aeromonas sp. OM4, and Serratia sp. OM17, capable of anaerobic growth with As (V reduction, were isolated from microbial mats from an ancient gold mine. All of the isolated strains: (i produced siderophores that promote dissolution of minerals, (ii were resistant to dissolved arsenic compounds, (iii were able to use the dissolved arsenates as the terminal electron acceptor, and (iii were able to use copper minerals containing arsenic minerals (e.g., enargite as a respiratory substrate. Based on the results obtained in this study, we postulate that arsenic can be released from some As-bearing polymetallic minerals (such as copper ore concentrates or middlings under reductive conditions by dissimilatory arsenate reducers in indirect processes.

  18. Pupillary responses to chromatic stimulus

    Science.gov (United States)

    Suaste-Gomez, Ernesto; Rodriguez Guzman, M. C. Ma. Dolores A.; Druzgalski, Christopher

    2000-06-01

    Pupillary responses of the subjects under chromatic visual stimulation were filmed with video-oculography systems (VOG). Specifically, programmable chromatic visual stimuli were displayed on the monitor of a personal computer (PC) and responses tested in several normal subjects and those with ophthalmic pathologic conditions. Visual excitation utilized a reversal stimulus checkerboard pattern. Image processing techniques were applied in order to evaluate the pupil variations due to chromatic stimulation. In particular, the studies determined a relationship between pupillary response (PR) and steady-state retinal sensitivity (photopic vision). Finally, the retinal illuminance in trolands (td), as a product of the pupil area in mm2 and luminance in cd/m2 to full-field chromatic stimulation (FFCS) and checkerboard pattern reversal chromatic stimulation (CPRCS) was determined.

  19. High-level chromate resistance in Arthrobacter sp. strain FB24 requires previously uncharacterized accessory genes

    Directory of Open Access Journals (Sweden)

    Thompson Dorothea K

    2009-09-01

    Full Text Available Abstract Background The genome of Arthrobacter sp. strain FB24 contains a chromate resistance determinant (CRD, consisting of a cluster of 8 genes located on a 10.6 kb fragment of a 96 kb plasmid. The CRD includes chrA, which encodes a putative chromate efflux protein, and three genes with amino acid similarities to the amino and carboxy termini of ChrB, a putative regulatory protein. There are also three novel genes that have not been previously associated with chromate resistance in other bacteria; they encode an oxidoreductase (most similar to malate:quinone oxidoreductase, a functionally unknown protein with a WD40 repeat domain and a lipoprotein. To delineate the contribution of the CRD genes to the FB24 chromate [Cr(VI] response, we evaluated the growth of mutant strains bearing regions of the CRD and transcript expression levels in response to Cr(VI challenge. Results A chromate-sensitive mutant (strain D11 was generated by curing FB24 of its 96-kb plasmid. Elemental analysis indicated that chromate-exposed cells of strain D11 accumulated three times more chromium than strain FB24. Introduction of the CRD into strain D11 conferred chromate resistance comparable to wild-type levels, whereas deletion of specific regions of the CRD led to decreased resistance. Using real-time reverse transcriptase PCR, we show that expression of each gene within the CRD is specifically induced in response to chromate but not by lead, hydrogen peroxide or arsenate. Higher levels of chrA expression were achieved when the chrB orthologs and the WD40 repeat domain genes were present, suggesting their possible regulatory roles. Conclusion Our findings indicate that chromate resistance in Arthrobacter sp. strain FB24 is due to chromate efflux through the ChrA transport protein. More importantly, new genes have been identified as having significant roles in chromate resistance. Collectively, the functional predictions of these additional genes suggest the

  20. Selective reduction of Cr(VI) in chromium, copper and arsenic (CCA) mixed waste streams using UV/TiO2 photocatalysis.

    Science.gov (United States)

    Zheng, Shan; Jiang, Wenjun; Rashid, Mamun; Cai, Yong; Dionysiou, Dionysios D; O'Shea, Kevin E

    2015-02-03

    The highly toxic Cr(VI) is a critical component in the Chromated Copper Arsenate (CCA) formulations extensively employed as wood preservatives. Remediation of CCA mixed waste and discarded treated wood products is a significant challenge. We demonstrate that UV/TiO2 photocatalysis effectively reduces Cr(VI) to less toxic Cr(III) in the presence of arsenate, As(V), and copper, Cu(II). The rapid conversion of Cr(VI) to Cr(III) during UV/TiO2 photocatalysis occurs over a range of concentrations, solution pH and at different Cr:As:Cu ratios. The reduction follows pseudo-first order kinetics and increases with decreasing solution pH. Saturation of the reaction solution with argon during UV/TiO2 photocatalysis had no significant effect on the Cr(VI) reduction demonstrating the reduction of Cr(VI) is independent of dissolved oxygen. Reduction of Cu(II) and As(V) does not occur under the photocatalytic conditions employed herein and the presence of these two in the tertiary mixtures had a minimal effect on Cr(VI) reduction. The Cr(VI) reduction was however, significantly enhanced by the addition of formic acid, which can act as a hole scavenger and enhance the reduction processes initiated by the conduction band electron. Our results demonstrate UV/TiO2 photocatalysis effectively reduces Cr(VI) in mixed waste streams under a variety of conditions.

  1. Thermochemical investigations on uranyl phosphates and arsenates

    International Nuclear Information System (INIS)

    The results are described of a study of the thermochemical stability of anhydrous uranyl phosphates and arsenates. A number of aspects of chemical technological importance are indicated in detail. The synthesized anhydrous uranyl phosphates and arsenates were very hygroscopic, so that experiments on these compounds had to be carried out under moisture-free conditions. Further characterisation of these compounds are given, including a study of their thermal stabilities and phase relations. The uranyl phosphates reduced reversibly at temperatures of the order of 1100 to 16000C. This makes it possible to express their relative stabilities quantitatively, in terms of the oxygen pressures of the reduction reactions. The thermal decomposition of uranyl arsenates did not occur by reduction, as for the phosphates, but by giving off arsenic oxide vapour. The results of measurements of enthalpies of solution led to the determination of the enthalpies of formation, heat capacity and the standard entropies of the uranyl arsenates. The thermochemical functions at high-temperatures could consequently be calculated. Attention is paid to the possible formation of uranium arsenates, whose uranium has a valency lower than six, hitherto not reported in literature. It was not possible to prepare arsenates of tetravalent uranium. However, three new compounds were observed, one of these, UAsO5, was studied in some detail. (Auth.)

  2. Respiratory arsenate reductase as a bidirectional enzyme

    Science.gov (United States)

    Richey, C.; Chovanec, P.; Hoeft, S.E.; Oremland, R.S.; Basu, P.; Stolz, J.F.

    2009-01-01

    The haloalkaliphilic bacterium Alkalilimnicola ehrlichii is capable of anaerobic chemolithoautotrophic growth by coupling the oxidation of arsenite (As(III)) to the reduction of nitrate and carbon dioxide. Analysis of its complete genome indicates that it lacks a conventional arsenite oxidase (Aox), but instead possesses two operons that each encode a putative respiratory arsenate reductase (Arr). Here we show that one homolog is expressed under chemolithoautotrophic conditions and exhibits both arsenite oxidase and arsenate reductase activity. We also demonstrate that Arr from two arsenate respiring bacteria, Alkaliphilus oremlandii and Shewanella sp. strain ANA-3, is also biochemically reversible. Thus Arr can function as a reductase or oxidase. Its physiological role in a specific organism, however, may depend on the electron potentials of the molybdenum center and [Fe–S] clusters, additional subunits, or constitution of the electron transfer chain. This versatility further underscores the ubiquity and antiquity of microbial arsenic metabolism.

  3. Optimizing Chromatic Coupling Measurement in the LHC

    CERN Document Server

    Persson, Tobias

    2016-01-01

    Optimizing chromatic coupling measurement in the LHC Chromatic coupling introduces a dependency of transverse coupling with energy. LHC is equipped with skew sextupoles to compensate the possible adverse effects of chromatic coupling. In 2012 a beam-based correction was calculated and applied successfully for the fist time. However, the method used to reconstruct the chromatic coupling was dependent on stable tunes and equal chromaticities between the horizontal and vertical planes. In this article an improved method to calculate the chromatic coupling without these constraints is presented.

  4. Arsenate resistance in the unicellular marine diazotroph Crocosphaera watsonii

    Directory of Open Access Journals (Sweden)

    Sonya eDyhrman

    2011-10-01

    Full Text Available The toxic arsenate ion can behave as a phosphate analog, and this can result in arsenate toxicity especially in areas with elevated arsenate to phosphate ratios like the surface waters of the ocean gyres. In these systems, cellular arsenate resistance strategies would allow phytoplankton to ameliorate the effects of arsenate transport into the cell. Despite the potential coupling between arsenate and phosphate cycling in oligotrophic marine waters, relatively little is known about arsenate resistance in the nitrogen-fixing marine cyanobacteria that are key components of the microbial community in low nutrient systems. The unicellular diazotroph, Crocosphaera watsonii WH8501, was able to grow at reduced rates with arsenate additions up to 30 nM, and estimated arsenate to phosphate ratios of 6:1. The genome of strain WH8501 contains homologs for arsA, arsH, arsB and arsC, allowing for the reduction of arsenate to arsenite and the pumping of arsenite out of the cell. The short-term addition of arsenate to the growth medium had no effect on nitrogen fixation. However, arsenate addition did result in the up-regulation of the arsB gene with increasing arsenate concentrations, indicating the induction of the arsenate detoxification response. The arsB gene was also up-regulated by phosphorus stress in concert with a gene encoding the high-affinity phosphate binding protein pstS. Both genes were down-regulated when phosphate was re-fed to phosphorus-stressed cells. A field survey of surface water from the low phosphate western North Atlantic detected expression of C. watsonii arsB, suggestive of the potential importance of arsenate resistance strategies in this and perhaps other systems.

  5. Response to arsenate treatment in Schizosaccharomyces pombe and the role of its arsenate reductase activity.

    Directory of Open Access Journals (Sweden)

    Alejandro Salgado

    Full Text Available Arsenic toxicity has been studied for a long time due to its effects in humans. Although epidemiological studies have demonstrated multiple effects in human physiology, there are many open questions about the cellular targets and the mechanisms of response to arsenic. Using the fission yeast Schizosaccharomyces pombe as model system, we have been able to demonstrate a strong activation of the MAPK Spc1/Sty1 in response to arsenate. This activation is dependent on Wis1 activation and Pyp2 phosphatase inactivation. Using arsenic speciation analysis we have also demonstrated the previously unknown capacity of S. pombe cells to reduce As (V to As (III. Genetic analysis of several fission yeast mutants point towards the cell cycle phosphatase Cdc25 as a possible candidate to carry out this arsenate reductase activity. We propose that arsenate reduction and intracellular accumulation of arsenite are the key mechanisms of arsenate tolerance in fission yeast.

  6. Nanoporous sorbent material as an oral phosphate binder and for aqueous phosphate, chromate, and arsenate removal

    OpenAIRE

    Sangvanich, Thanapon; Ngamcherdtrakul, Worapol; Lee, Richard; Morry, Jingga; Castro, David; Fryxell, Glen E.; Yantasee, Wassana

    2014-01-01

    Phosphate removal is both biologically and environmentally important. Biologically, hyperphosphatemia is a critical condition in end-stage chronic kidney disease patients. Patients with hyperphosphatemia are treated long-term with oral phosphate binders to prevent phosphate absorption to the body by capturing phosphate in the gastrointestinal (GI) tract followed by fecal excretion. Environmentally, phosphate levels in natural water resources must be regulated according to limits set forth by ...

  7. Goethite surface reactivity: III. Unifying arsenate adsorption behavior through a variable crystal face - Site density model

    Science.gov (United States)

    Salazar-Camacho, Carlos; Villalobos, Mario

    2010-04-01

    goethite, may be performed for each preparation either by experimental determination of site saturation by an index ion (e.g., chromate), or by achieving congruency of proton adsorption data with those of ideal goethites when plotted as percentage of proton-reactive ( lbond2 FeOH + lbond2 Fe 3OH) sites occupied. The surface arsenate complexes proposed additionally explained: (1) the higher affinity of goethite for As(V) than for Cr(VI) at high pH, and thus the gentle slope of the arsenate pH adsorption edges; and (2) the lower adsorption capacity for As(V) than for Cr(VI) at low pH on low-surface area goethites, through incomplete lbond2 FeOH site occupancy of As(V). The model is very promising as a practical means of predicting the adsorption behavior of arsenate on any goethite preparation, and may extend to predictive capabilities for adsorption behavior of many other relevant oxyanions, as well as for explaining differences in ligand-promoted surface transformation processes on goethite as a function of particle size.

  8. Chromatic roots and hamiltonian paths

    DEFF Research Database (Denmark)

    Thomassen, Carsten

    2000-01-01

    We present a new connection between colorings and hamiltonian paths: If the chromatic polynomial of a graph has a noninteger root less than or equal to t(n) = 2/3 + 1/3 (3)root (26 + 6 root (33)) + 1/3 (3)root (26 - 6 root (33)) = 1.29559.... then the graph has no hamiltonian path. This result is...

  9. Thermochemical investigations on uranyl phosphates and arsenates

    International Nuclear Information System (INIS)

    Results are described of a study of the thermochemical stability of anhydrous phosphates and arsenates. The results of phase studies deal with compound formation and characterization, coexisting phases and limiting physical or chemical properties. The uranyl phosphates evolve oxygen at higher temperatures and the arsenates lose arsenic oxide vapour. These phenomena give the possibility to describe their thermodynamic stabilities. Thus oxygen pressures of uranyl phosphates have been measured using a static, non-isothermal method. Having made available the pure anhydrous compounds in the course of this investigation, molar thermodynamic quantities have been measured as well. These include standard enthalpies of formation from solution calorimetry and high-temperature heat-capacity functions derived from enthalpy increments measured. Some attention is given to compounds with uranium in valencies lower than six which have been met during the investigation. An evaluation is made of the thermodynamics of the compounds studied, to result in tabulized high-temperature thermodynamic functions. Relative stabilities within the systems are discussed and comparisons of the uranyl phosphates and the arsenates are made. (Auth.)

  10. Semantics of color in chromatism

    Science.gov (United States)

    Serov, Nikolai V.

    2002-06-01

    The aim of this investigation is to describe the semantics of color in chromatism (from the ancient Greek triune notion of >: (1) color as ideal (Id- plan), psychic; (2) tint as physical, verbal; material (M- plan), physiological, syntonic (S-plan), and (3) emotion as their informative-energetic correlation). Being a new field of science, chromatism links humanitarian and natural subjects by means of interdiscipline investigation of a real (f-m) man living in a real (color) surrounding environment. According to the definition for >, color may be considered to be the most universal notion, permitting to assume the unity of both a man and an environment. Due to this assumption, we may give models of human intellect.

  11. Exploring a chromatic oblique effect.

    OpenAIRE

    Curran, Paul G.

    1997-01-01

    Approved for public release; distribution is unlimited For centuries, military forces have used camouflage to obscure potential targets from the enemy. Because the eye is fairly adept at picking out edges, colors, and bright areas, camouflage is often used to degrade these qualities from human detection. The purpose of this thesis was to investigate the role of certain spatial, temporal, and chromatic features on the human visual system and how these features may aid the quest for better c...

  12. Competitive and cooperative adsorption of arsenate and citrate on goethite

    Institute of Scientific and Technical Information of China (English)

    SHI Rong; JIA Yongfeng; WANG Chengzhi

    2009-01-01

    The fate of arsenic in natural environments is influenced by adsorption onto metal (hydr)oxides. The extent of arsenic adsorption is strongly affected by coexisting dissolved natural organic acids. Recently, some studies reported that there existed competitive adsorption between arsenate and citrate on goethite. Humic acid is known to interact strongly with arsenate by forming complexes in aqueous solution, hence it is necessary to undertake a comprehensive study of the adsorption of arsenate/citrate onto goethite in the presence of one another. The results showed that at the arsenate concentrations used in this study (0.006--0.27 mmol/L), citrate decreased arsenate adsorption at acidic pH but no effect was observed at alkaline pH. In comparison, citrate adsorption was inhibited at acidic pH, but enhanced at alkaline pH by arsenate. This was probably due to the formation of complex between arsenate and citrate like the case of arsenate with humic acid. These results implied that the mechanism of the adsorption of arsenate and citrate onto goethite in the presence of one another involved not only competition for binding sites, but the cooperation between the two species at the water-goethite interface as well.

  13. Inhibition of microbial arsenate reduction by phosphate.

    Science.gov (United States)

    Slaughter, Deanne C; Macur, Richard E; Inskeep, William P

    2012-03-20

    The ratio of arsenite (As(III)) to arsenate (As(V)) in soils and natural waters is often controlled by the activity of As-transforming microorganisms. Phosphate is a chemical analog to As(V) and, consequently, may competitively inhibit microbial uptake and enzymatic binding of As(V), thus preventing its reduction to the more toxic, mobile, and bioavailable form - As(III). Five As-transforming bacteria isolated either from As-treated soil columns or from As-impacted soils were used to evaluate the effects of phosphate on As(V) reduction and As(III) oxidation. Cultures were initially spiked with various P:As ratios, incubated for approximately 48 h, and analyzed periodically for As(V) and As(III) concentration. Arsenate reduction was inhibited at high P:As ratios and completely suppressed at elevated levels of phosphate (500 and 1,000 μM; P inhibition constant (K(i))∼20-100 μM). While high P:As ratios effectively shut down microbial As(V) reduction, the expression of the arsenate reductase gene (arsC) was not inhibited under these conditions in the As(V)-reducing isolate, Agrobacterium tumefaciens str. 5B. Further, high phosphate ameliorated As(V)-induced cell growth inhibition caused by high (1mM) As pressure. These results indicate that phosphate may inhibit As(V) reduction by impeding As(V) uptake by the cell via phosphate transport systems or by competitively binding to the active site of ArsC. PMID:21741807

  14. Atom lens without chromatic aberrations

    CERN Document Server

    Efremov, Maxim A; Schleich, Wolfgang P

    2012-01-01

    We propose a lens for atoms with reduced chromatic aberrations and calculate its focal length and spot size. In our scheme a two-level atom interacts with a near-resonant standing light wave formed by two running waves of slightly different wave vectors, and a far-detuned running wave propagating perpendicular to the standing wave. We show that within the Raman-Nath approximation and for an adiabatically slow atom-light interaction, the phase acquired by the atom is independent of the incident atomic velocity.

  15. Chromatic Polynomials of Mixed Hypercycles

    Directory of Open Access Journals (Sweden)

    Allagan Julian A.

    2014-08-01

    Full Text Available We color the vertices of each of the edges of a C-hypergraph (or cohypergraph in such a way that at least two vertices receive the same color and in every proper coloring of a B-hypergraph (or bihypergraph, we forbid the cases when the vertices of any of its edges are colored with the same color (monochromatic or when they are all colored with distinct colors (rainbow. In this paper, we determined explicit formulae for the chromatic polynomials of C-hypercycles and B-hypercycles

  16. CIRCULAR CHROMATIC NUMBER AND MYCIELSKI GRAPHS

    Institute of Scientific and Technical Information of China (English)

    Liu Hongmei

    2006-01-01

    For a general graph G, M(G) denotes its Mycielski graph. This article gives a number of new sufficient conditions for G to have the circular chromatic number xc (M(G))equals to the chromatic number x(M(G)), which have improved some best sufficient conditions published up to date.

  17. Quantum chromatic numbers via operator systems

    OpenAIRE

    Paulsen, Vern I.; Todorov, Ivan G.

    2013-01-01

    We define several new types of quantum chromatic numbers of a graph and characterise them in terms of operator system tensor products. We establish inequalities between these chromatic numbers and other parameters of graphs studied in the literature and exhibit a link between them and non-signalling correlation boxes.

  18. CHROMATIC ZEROS AND THE GOLDEN RATIO

    Directory of Open Access Journals (Sweden)

    Yee-hock Peng

    2009-02-01

    Full Text Available In this note, we investigate $au^n$, where au=fracc{1+sqrt{5}}{2}$is the golden ratio as chro-matic roots. Using some properties of {sc Fibonacci} numbers, we prove that $au^n (nin mathbb{N}$, cannot be roots of any chromatic polynomial.

  19. On chromatic and geometrical calibration

    DEFF Research Database (Denmark)

    Folm-Hansen, Jørgen

    1999-01-01

    we present the implementation of a complete calibration method for an accurate colour texture measurement device called VMX2000, the calibration for uneven laser sheet illumination in a flow measuring system and the use of automatic detection of calibration targets for a DLT/warping in a 3D PIV......The main subject of the present thesis is different methods for the geometrical and chromatic calibration of cameras in various environments. For the monochromatic issues of the calibration we present the acquisition of monochrome images, the classic monochrome aberrations and the various sources...... of non-uniformity of the illumination of the image plane. Only the image deforming aberrations and the non-uniformity of illumination are included in the calibration models. The topics of the pinhole camera model and the extension to the Direct Linear Transform (DLT) are described. It is shown how...

  20. Chromatic adaptation performance of different RGB sensors

    Science.gov (United States)

    Susstrunk, Sabine E.; Holm, Jack M.; Finlayson, Graham D.

    2000-12-01

    Chromatic adaptation transforms are used in imaging system to map image appearance to colorimetry under different illumination sources. In this paper, the performance of different chromatic adaptation transforms (CAT) is compared with the performance of transforms based on RGB primaries that have been investigated in relation to standard color spaces for digital still camera characterization and image interchange. The chromatic adaptation transforms studied are von Kries, Bradford, Sharp, and CMCCAT2000. The RGB primaries investigated are ROMM, ITU-R BT.709, and 'prime wavelength' RGB. The chromatic adaptation model used is a von Kries model that linearly scales post-adaptation cone response with illuminant dependent coefficients. The transforms were evaluated using 16 sets of corresponding color dat. The actual and predicted tristimulus values were converted to CIELAB, and three different error prediction metrics, (Delta) ELab, (Delta) ECIE94, and (Delta) ECMC(1:1) were applied to the results. One-tail Student-t tests for matched pairs were calculated to compare if the variations in errors are statistically significant. For the given corresponding color data sets, the traditional chromatic adaptation transforms, Sharp CAT and CMCCAT2000, performed best. However, some transforms based on RGB primaries also exhibit good chromatic adaptation behavior, leading to the conclusion that white-point independent RGB spaces for image encoding can be defined. This conclusion holds only if the linear von Kries model is considered adequate to predict chromatic adaptation behavior.

  1. Chromate conversion coatings and their current application

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2016-04-01

    Full Text Available This paper describes formation, composition and possible production technologies of application chromate coatings. Summation of common examples of applications of these coatings in corrosion protection of metals and alloys is provided. Individual chromate coatings are divided by their dominant anions either with CrVI or CrIII. Restrictions of chromate coatings with dominantly CrVI and related toxicity of hexavalent chromium is discussed in detail. In conclusion, examples of both chromium and other, alternative coatings are summed up. Application of these coatings as a protection for concrete hot-dip galvanized reinforcement is also reviewed.

  2. Phosphate transport and arsenate resistance in the cyanobacterium Anabaena variabilis.

    OpenAIRE

    Thiel, T.

    1988-01-01

    Cells of the cyanobacterium Anabaena variabilis starved for phosphate for 3 days took up phosphate at about 100 times the rate of unstarved cells. Kinetic data suggested that a new transport system had been induced by starvation for phosphate. The inducible phosphate transport system was quickly repressed by addition of Pi. Phosphate-starved cells were more sensitive to the toxic effects of arsenate than were unstarved cells, but phosphate could alleviate some of the toxicity. Arsenate was a ...

  3. Effect of Competing Anions on Arsenate Adsorption onto Maghemite Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    T. Tuutijarvi; E. Repo; R. Vahala; M. Sillanpaa; G. Chen

    2012-01-01

    This paper reports the effect of several competing anions on arsenate adsorption with maghemite nanoparticles. Sulphate (as SO4), nitrate (as NO3-N), phosphate (as PO4-P) ions and silicate-(as SiO2) were-studied in dual solution with arsenate. Moreover, the combined effect of ions and other water characteristics were examined with a natural groundwater sample which was spiked with a certain amount of arsenate. Arsenate batch adsorption experiments were carried out with two different kinds of maghemite-a commercially, available one and a homemade one using the sol-gel orocess. Sulohate (≤250 mg.L-1) and nitrate (≤ 12 mg.L-1) had a neglivible effect onthe arsenate (0.5 mg.L-1) adsorption at pH 3. However, both phosphate (42.9 mg·L-1) and silicate (450 mg.L-j) had an adverse impact on arsenate (43 mg.L-1) adsorption at pH 7. Phosphate (41.5 mg.L-1) showed minimal competition with arsenate (0.5 mg.L-1), while silicate (410 mg.L-1) inhibition was insignificant for all studied As(V) concentrations at p.H 3. The removal of arsenate from the groundwater sample was as efficient as from labo-ratory water tor 0.3 mgL -1 AS(V) botll at pH3 and pH7.

  4. Diffractive elements performance in chromatic confocal microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Garzon, J; Duque, D; Alean, A; Toledo, M [Grupo de Optica y EspectroscopIa, Centro de Ciencia Basica, Universidad Pontificia Bolivariana. Medellin (Colombia); Meneses, J [Laboratorio de Optica y Tratamiento de Senales, Instituto de Fisica, Universidad Industrial de Santander, Bucaramanga (Colombia); Gharbi, T, E-mail: jgarzonr10@une.net.co [Laboratoire d' Optique P. M. Duffieux, UMR-6603 CNR/Universite de Franche-Comte. 16 route de Gray, 25030 Besancon Cedex (France)

    2011-01-01

    The Confocal Laser Scanning Microscopy (CLSM) has been widely used in the semiconductor industry and biomedicine because of its depth discrimination capability. Subsequent to this technique has been developed in recent years Chromatic Confocal Microscopy. This method retains the same principle of confocal and offers the added advantage of removing the axial movement of the moving system. This advantage is usually accomplished with an optical element that generates a longitudinal chromatic aberration and a coding system that relates the axial position of each point of the sample with the wavelength that is focused on each. The present paper shows the performance of compact chromatic confocal microscope when some different diffractive elements are used for generation of longitudinal chromatic aberration. Diffractive elements, according to the process and manufacturing parameters, may have different diffraction efficiency and focus a specific wavelength in a specific focal position. The performance assessment is carried out with various light sources which exhibit an incoherent behaviour and a broad spectral width.

  5. Chromatic effects in long periodic transport channels

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko V. N.; Hao, Y.; Jing, Y.

    2015-05-03

    Long periodic transport channels are frequently used in accelerator complexes and suggested for using in high-energy ERLs for electron-hadron colliders. Without proper chromaticity compensation, such transport channels exhibit high sensitivity to the random orbit errors causing significant emittance growth. Such emittance growth can come from both the correlated and the uncorrelated energy spread. In this paper we present results of our theoretical and numerical studies of such effects and develop a criteria for acceptable chromaticity in such channels.

  6. Chromatic variations suppress suprathreshold brightness variations

    OpenAIRE

    KINGDOM, FREDERICK A.A.; Bell, Jason; Gheorghiu, Elena; Malkoç, Gökhan

    2010-01-01

    Most objects in natural scenes are suprathreshold in both color (chromatic) and luminance contrast. How salient is each dimension? We have developed a novel method employing a stimulus similar to that used by B. C. Regan and J. D. Mollon (1997) who studied the relative saliencies of the two chromatic cardinal directions. Our stimuli consist of left-and right-oblique modulations of color and/or luminance defined within a lattice of circles. In the "separated" condition, the two modulations wer...

  7. Arsenic-Lipid Complex Formation During the Active Transport of Arsenate in Yeast

    Science.gov (United States)

    Cerbón, Jorge

    1969-01-01

    In studying formation of an arsenic-lipid complex during the active transport of 74As-arsenate in yeast, it was found that adaptation of yeast to arsenate resulted in cell populations which showed a deficient inflow of arsenate as compared to the nonadapted yeast. Experiments with both types of cells showed a direct correlation between the arsenate taken up and the amount of As-lipid complex formed. 74As-arsenate was bound exclusively to the phosphoinositide fraction of the cellular lipids. When arsenate transport was inhibited by dinitrophenol and sodium azide, the formation of the As-lipid complex was also inhibited. Phosphate did not interfere with the arsenate transport at a non-inhibitory concentration of external arsenate (10−9m). The As-adapted cells but not the unadapted cells were able to take up phosphate when growing in the presence of 10−2m arsenate. PMID:5773018

  8. Arsenic-lipid complex formatinon during the active transport of arsenate in yeast.

    Science.gov (United States)

    Cerbón, J

    1969-02-01

    In studying formation of an arsenic-lipid complex during the active transport of (74)As-arsenate in yeast, it was found that adaptation of yeast to arsenate resulted in cell populations which showed a deficient inflow of arsenate as compared to the nonadapted yeast. Experiments with both types of cells showed a direct correlation between the arsenate taken up and the amount of As-lipid complex formed. (74)As-arsenate was bound exclusively to the phosphoinositide fraction of the cellular lipids. When arsenate transport was inhibited by dinitrophenol and sodium azide, the formation of the As-lipid complex was also inhibited. Phosphate did not interfere with the arsenate transport at a non-inhibitory concentration of external arsenate (10(-9)m). The As-adapted cells but not the unadapted cells were able to take up phosphate when growing in the presence of 10(-2)m arsenate. PMID:5773018

  9. Arsenate and phosphate interaction in Saccharomyces cerevisiae

    Institute of Scientific and Technical Information of China (English)

    GENG Chun-nu; ZHU Yong-guan

    2006-01-01

    In the present study, arsenate(As(Ⅴ)) and phosphate(P(Ⅴ)) interactions were investigated in growth, uptake and RNA content in yeast(Saccharomyces cerevisiae). Yeast grew slowly with As(Ⅴ) concentrations increasing in the medium. However, the maximal population density was almost the same among different As(Ⅴ) treatments. It was in the late log phase that yeast growth was augmented by low As(Ⅴ), which was maybe due to the fact that methionine metabolism was stressed by vitamin B6 deprivation, so As(Ⅴ)treatments did not affect maximal population density. However, with P (Ⅴ) concentrations increasing, the maximal population density increased. Therefore, the maximal population density was determined by P (Ⅴ) concentrations in the medium but not by As (Ⅴ)concentrations in the medium. Ycf1p(a tonoplast transpor) transports As(GS)3 into the vacuole, but arsenic(As) remaining in the thalli was 1.27% with As(Ⅴ) exposure for 60 h, from which it can be speculated that the percentage of As transported into vacuole should be lower than 1.27%. However, the percentage of As pumped out of cell was 71.49% with As (Ⅴ) exposure for 68 h. Although two pathways (extrusion and sequestration) were involved in As detoxification in yeast, the extrusion pathway played a major role in As detoxification. RNA content was the highest in the early-log phase and was reduced by As(Ⅴ).

  10. Mobility of copper, chromium and arsenic from treated timber into grapevines.

    Science.gov (United States)

    Ko, Byong-Gu; Vogeler, Iris; Bolan, Nanthi S; Clothier, Brent; Green, Steve; Kennedy, John

    2007-12-15

    The use of chromated copper arsenate (CCA) treated timber posts as support structures in New Zealand vineyards has raised concerns regarding the release of heavy metal(loid)s from the treated timber into the environment. A laboratory experiment was set up to evaluate if post sealing by painting reduces the release rate of CCA metal(loid)s from timber posts. Three posts were painted (Gripset 38, Multi Purpose Bitumen Rubber) on the bottom part, submerged in freshwater, and the concentrations of copper (Cu), chromium (Cr) and arsenic (As) in the water were monitored over a period of 8 months. Three additional, unpainted posts were also used. The CCA contents in the water showed a clear difference between the painted and the unpainted posts, and painting the bottom of the posts reduced the release rate by 50-75%. To monitor the possible mobility of CCA from treated posts into grapevines further, an experiment with four-year-old grapevines planted into sixteen lysimeters was set up in a greenhouse. To half the lysimeters Cu, Cr and As were added to the soil surface at rates of 16, 20, and 12.5 mg/month from 15 November 2005 to 5 May 2006. The other lysimeters acted as a control. Soil solutions were collected at 50, 150 and 300 mm depths using suction cups after seven application of the CCA solution. The results showed that all the elements moved to a depth of 50 mm. Grape fruit, leaves and rachis were analysed for CCA metal(loid)s, but did not show any differences between the CCA-treated and control lysimeters. This indicated either that these metals were not taken up by grapevines or that their translocation from roots to the upper part of the vine was negligible. Further monitoring of CCA metal(loid)s in various parts of the grapevines, including roots, needs to be undertaken. PMID:17889258

  11. Sorptive removal of arsenate using termite mound.

    Science.gov (United States)

    Fufa, Fekadu; Alemayehu, Esayas; Lennartz, Bernd

    2014-01-01

    Long-term consumption of arsenic results in severe and permanent health damages. The aim of the study was to investigate arsenate (As(V)) sorption capacity of termite mound (TM), containing mainly silicon, aluminum, iron and titanium oxides, under batch adsorption setup. The pattern of As(V) removal with varying contact time, solution pH, adsorbent dose, As(V) concentration and competing anions was investigated. Dissolution of the adsorbent was insignificant under the equilibrium conditions. Equilibrium was achieved within 40 min of agitation time. Kinetic data of As(V) adsorption followed well the pseudo-second order equation (R(2) > 0.99). High As(V) removal efficiency (∼ 99%) was observed over a pH range ∼ 3-∼ 10, which is of great importance in the practical application. The Freundlich and Dubinin-Radushkevich isotherms well described (R(2) > 0.99, χ(2) ∼ 0.05) the equilibrium As(V) adsorption, giving a coefficient of adsorption 1.48 mg(1-1/n)L(1/n)/g and a saturation capacity 13.50 mg/g respectively. The obtained value of mean sorption energy (EDR = 13.32 kJ/mol) suggested the chemisorption mechanism of As(V) adsorption on TM. The removal of As(V) was significantly decreased in the presence of phosphate ions. The As(V) loaded adsorbent was successfully regenerated using NaOH solution with insignificant loss of metals. Therefore, the results of the study demonstrated that TM could be considered as a promising adsorbent for the treatment of As(V) in drinking water. PMID:24309232

  12. Color constancy by characterization of illumination chromaticity

    Science.gov (United States)

    Nikkanen, Jarno T.

    2011-05-01

    Computational color constancy algorithms play a key role in achieving desired color reproduction in digital cameras. Failure to estimate illumination chromaticity correctly will result in invalid overall colour cast in the image that will be easily detected by human observers. A new algorithm is presented for computational color constancy. Low computational complexity and low memory requirement make the algorithm suitable for resource-limited camera devices, such as consumer digital cameras and camera phones. Operation of the algorithm relies on characterization of the range of possible illumination chromaticities in terms of camera sensor response. The fact that only illumination chromaticity is characterized instead of the full color gamut, for example, increases robustness against variations in sensor characteristics and against failure of diagonal model of illumination change. Multiple databases are used in order to demonstrate the good performance of the algorithm in comparison to the state-of-the-art color constancy algorithms.

  13. Chromatic corrections for large storage rings

    International Nuclear Information System (INIS)

    The use of achromat concept (1) to facilitate chromatic corrections in large storage rings is illustrated. The example given in this report is a lattice for a 75 GeV/c ring with six interaction regions having a beta x = 1.6 m, a beta y = 0.1 m and a luminosity of 1.4 1032 cm-2s-1. The chromatic corrections are done with four families of sextupoles, two for each transverse plane, the strengths of which are determined by the solution of four linear equations in four unknowns. The basic simplicity of the method allows on-line control of the sextupole adjustments

  14. Structure and Growth Mechanism of Lanthanum Chromate

    Institute of Scientific and Technical Information of China (English)

    Li Shengli; Liu Weiming; Ling Ziyu; Sun Liangcheng; Ao Qing; Fu Guifu

    2005-01-01

    The unit cell of lanthanum chromate was constructed by calculating equivalent points. By means of calculation of the hole octahedrally surrounded by O2- ions, it was considered that the sintered property of lanthanum chromate and the stability of Cr-O octahedron might be promoted by mixing a little Ca2+ ions. The growth mechanism was discussed in terms of structural ledge observed by SEM, the surfaces of the structural ledges parallel to (001), (010) and (110) planes, respectively. The misfit between (110) and (001) planes is only 0.0021 on common atomic plane, and the interconnection of the structured ledge may occur during crystal growth.

  15. Preliminary studies of a chromaticity tracker

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Cheng-Yang; /Fermilab

    2006-03-01

    A chromaticity tracker based on a method by D. McGinnis is proposed. This method starts with the slow modulation of the accelerating RF which causes the beam to respond to it. This beam modulation can be detected transversely with a Schottky pickup which after phase demodulation, the chromaticity can be calculated from it. However, to perform phase demodulation, the carrier frequency which is the betatron tune needs to be identified. The identification of the carrier frequency falls naturally onto the phase locked loop tune tracker which when locked to the betatron tune outputs this value in real time.

  16. Total dominator chromatic number of a graph

    Directory of Open Access Journals (Sweden)

    Adel P. Kazemi

    2015-06-01

    Full Text Available Given a graph $G$, the total dominator coloring problem seeks a proper coloring of $G$ with the additional property that every vertex in the graph is adjacent to all vertices of a color class. We seek to minimize the number of color classes. We initiate to study this problem on several classes of graphs, as well as finding general bounds and characterizations. We also compare the total dominator chromatic number of a graph with the chromatic number and the total domination number of it.

  17. The chromatic polynomial and list colorings

    DEFF Research Database (Denmark)

    Thomassen, Carsten

    2009-01-01

    We prove that, if a graph has a list of k available colors at every vertex, then the number of list-colorings is at least the chromatic polynomial evaluated at k when k is sufficiently large compared to the number of vertices of the graph.......We prove that, if a graph has a list of k available colors at every vertex, then the number of list-colorings is at least the chromatic polynomial evaluated at k when k is sufficiently large compared to the number of vertices of the graph....

  18. Sorption and desorption of arsenate and arsenite on calcite

    DEFF Research Database (Denmark)

    Sø, Helle Ugilt; Postma, Diederik Jan; Jakobsen, Rasmus;

    2008-01-01

    The adsorption and desorption of arsenate (As(V)) and arsenite (As(111)) oil calcite was investigated in a series of batch experiments in calcite-equilibrated solutions. The solutions covered a broad range of pH, alkalinity, calcium concentration and ionic strength. The initial arsenic concentrat......The adsorption and desorption of arsenate (As(V)) and arsenite (As(111)) oil calcite was investigated in a series of batch experiments in calcite-equilibrated solutions. The solutions covered a broad range of pH, alkalinity, calcium concentration and ionic strength. The initial arsenic...

  19. Variability of chromatic sensitivity: fundamental studies and clinical applications

    OpenAIRE

    Carmona, M. L. R.

    2006-01-01

    This investigation involved a number of related studies with the principal aim of assessing the variability in chromatic sensitivity in "normal" trichromats and colour deficient observers. An important outcome was the development of a new method for accurate and efficient measurement of chromatic sensitivity and the establishment of reliable statistical limits that describe the distribution of redgreen(RG) and yellow-blue (YB) chromatic sensitivity in normal trichromats. Chromatic sensitivity...

  20. On the Star Chromatic Number of Graph Products

    Institute of Scientific and Technical Information of China (English)

    XU Chuan-liang; WANG Yi-ju

    2001-01-01

    The star chromatic number of a graph was introduced by A. Vince, which is a natural generalization of the chromatic number of a graph. In this paper, the star chromatic numbers of graph products G (×) H are discussed in some special cases.

  1. Membrane-associated chromate reductase activity from Enterobacter cloacae.

    OpenAIRE

    P. C. Wang; Mori, T.; Toda, K.; Ohtake, H

    1990-01-01

    Washed cells of Enterobacter cloacae HO1 reduced hexavalent chromium (chromate: CrO4(2-) anaerobically. Chromate reductase activity was preferentially associated with the membrane fraction of the cells. Right-side-out membrane vesicles prepared from E. cloacae cells showed high chromate reductase activities when ascorbate-reduced phenazine methosulfate was added as an electron donor.

  2. Vibrometry using a chromatic confocal sensor

    Science.gov (United States)

    Berkovic, G.; Zilberman, S.; Shafir, E.; Cohen-Sabban, J.

    2014-05-01

    We demonstrate vibrometry using a chromatic confocal sensor which measures displacements with 0.1 μm resolution at a rate of 10 kHz. This technique was used to study the vibration of a musical tuning fork with a resonance at 523 Hz. Other examples presented include vibration of water waves and multiple point vibrometry of a vibrating steel rod.

  3. Chromatic Dispersion Estimation in Digital Coherent Receivers

    DEFF Research Database (Denmark)

    Soriano, Ruben Andres; Hauske, Fabian N.; Guerrero Gonzalez, Neil;

    2011-01-01

    Polarization-diverse coherent demodulation allows to compensate large values of accumulated linear distortion by digital signal processing. In particular, in uncompensated links without optical dispersion compensation, the parameter of the residual chromatic dispersion (CD) is vital to set the ac...

  4. Anti-forensics of chromatic aberration

    Science.gov (United States)

    Mayer, Owen; Stamm, Matthew C.

    2015-03-01

    Over the past decade, a number of information forensic techniques have been developed to identify digital image manipulation and falsification. Recent research has shown, however, that an intelligent forger can use anti-forensic countermeasures to disguise their forgeries. In this paper, an anti-forensic technique is proposed to falsify the lateral chromatic aberration present in a digital image. Lateral chromatic aberration corresponds to the relative contraction or expansion between an image's color channels that occurs due to a lens's inability to focus all wavelengths of light on the same point. Previous work has used localized inconsistencies in an image's chromatic aberration to expose cut-and-paste image forgeries. The anti-forensic technique presented in this paper operates by estimating the expected lateral chromatic aberration at an image location, then removing deviations from this estimate caused by tampering or falsification. Experimental results are presented that demonstrate that our anti-forensic technique can be used to effectively disguise evidence of an image forgery.

  5. Arsenate Adsorption On Ruthenium Oxides: A Spectroscopic And Kinetic Investigation

    Science.gov (United States)

    Arsenate adsorption on amorphous (RuO2•1.1H2O) and crystalline (RuO2) ruthenium oxides was evaluated using spectroscopic and kinetic methods to elucidate the adsorption mechanism. Extended X-ray absorption fine structure spectroscopy (EXAFS) was ...

  6. Rice-arsenate interactions in hydroponics: whole genome transcriptional analysis.

    Science.gov (United States)

    Norton, Gareth J; Lou-Hing, Daniel E; Meharg, Andrew A; Price, Adam H

    2008-01-01

    Rice (Oryza sativa) varieties that are arsenate-tolerant (Bala) and -sensitive (Azucena) were used to conduct a transcriptome analysis of the response of rice seedlings to sodium arsenate (AsV) in hydroponic solution. RNA extracted from the roots of three replicate experiments of plants grown for 1 week in phosphate-free nutrient with or without 13.3 muM AsV was used to challenge the Affymetrix (52K) GeneChip Rice Genome array. A total of 576 probe sets were significantly up-regulated at least 2-fold in both varieties, whereas 622 were down-regulated. Ontological classification is presented. As expected, a large number of transcription factors, stress proteins, and transporters demonstrated differential expression. Striking is the lack of response of classic oxidative stress-responsive genes or phytochelatin synthases/synthatases. However, the large number of responses from genes involved in glutathione synthesis, metabolism, and transport suggests that glutathione conjugation and arsenate methylation may be important biochemical responses to arsenate challenge. In this report, no attempt is made to dissect differences in the response of the tolerant and sensitive variety, but analysis in a companion article will link gene expression to the known tolerance loci available in the BalaxAzucena mapping population.

  7. Chromaticity measurement during beam energy ramp in Indus-2

    International Nuclear Information System (INIS)

    Chromaticity is one of the important parameters of circular accelerators and plays crucial role in its operation. In Indus-2 storage ring the natural chromaticity is -19 and -12 in horizontal and vertical planes respectively. For the good injection at 550 MeV in Indus-2, chromaticity needs to be kept at (+1, +1). The corrected chromaticity does not remain constant during the energy ramp up to 2.5 GeV. We measured Indus-2 storage ring chromaticity by the conventional RF frequency change method. The measurement method and the result of the measurement are reported in this paper. (author)

  8. Arsenate removal from water using sand--red mud columns.

    Science.gov (United States)

    Genç-Fuhrman, Hülya; Bregnhøj, Henrik; McConchie, David

    2005-08-01

    This study describes experiments in which sorption filters, filled with chemically modified red mud (Bauxsol) or activated Bauxsol (AB) coated sand, are used to remove As(V) (arsenate) from water. Bauxsol-coated sand (BCS) and AB-coated sand (ABCS) are prepared by mixing Bauxsol or AB with wet sand and drying. Samples of the BCS and ABCS are also used in batch experiments to obtain isotherm data. The observed adsorption data fit the Langmuir model well, with adsorption maxima of 3.32 and 1.64 mgg(-1) at pH values of 4.5 and 7.1, respectively for BCS; and of 2.14 mgg(-1) for ABCS at a pH of 7.1. Test results show that higher arsenate adsorption capacities can be achieved for both BCS and ABCS when using the columns compared to results for batch experiments; the difference is greater for BCS. Additional batch tests, carried out for 21 days using BCS to explain the observed discrepancy, show that the equilibrium time previously used in batch experiments was too short because adsorption continued for at least 21 days and reached 87% after 21 days compared to only 35% obtained after 4h. Fixed bed column tests, used to investigate the effects of flow rate and initial arsenate concentration indicate that the process is sensitive to both parameters, with lower flow rates (longer effective residence times in the columns) and initial arsenate concentrations providing better column performance. An examination of the combined effect of potential competing anions (i.e. silicate, phosphate, sulphate and bicarbonate) on the column performance showed that the presence of these anions in tap water slightly decreases arsenate removal. Each breakthrough curve is compared to the Thomas model, and it is found that the model may be applied to estimate the arsenate sorption capacity in columns filled with BCS and ABCS. The data obtained from both batch and column studies indicate that BCS and ABCS filtration could be effectively used to remove arsenate from water, with the latter being

  9. WASTE MINIMIZATION PRACTICES AT TWO CCA WOOD TREATMENT PLANTS

    Science.gov (United States)

    Two chromated copper arsenate (CCA) wood-treatment plants were assessed for their waste minimization practices. These practices have been reflected in several areas, including facility designs, process controls, and management practices. he objectives were to estimate the amount...

  10. Neural network correction of astrometric chromaticity

    CERN Document Server

    Gai, M

    2005-01-01

    In this paper we deal with the problem of chromaticity, i.e. apparent position variation of stellar images with their spectral distribution, using neural networks to analyse and process astronomical images. The goal is to remove this relevant source of systematic error in the data reduction of high precision astrometric experiments, like Gaia. This task can be accomplished thanks to the capability of neural networks to solve a nonlinear approximation problem, i.e. to construct an hypersurface that approximates a given set of scattered data couples. Images are encoded associating each of them with conveniently chosen moments, evaluated along the y axis. The technique proposed, in the current framework, reduces the initial chromaticity of few milliarcseconds to values of few microarcseconds.

  11. Schottky signal analysis: tune and chromaticity computation

    CERN Document Server

    Chanon, Ondine

    2016-01-01

    Schottky monitors are used to determine important beam parameters in a non-destructive way. The Schottky signal is due to the internal statistical fluctuations of the particles inside the beam. In this report, after explaining the different components of a Schottky signal, an algorithm to compute the betatron tune is presented, followed by some ideas to compute machine chromaticity. The tests have been performed with offline and/or online LHC data.

  12. The respiratory arsenate reductase from Bacillus selenitireducens strain MLS10

    Science.gov (United States)

    Afkar, E.; Lisak, J.; Saltikov, C.; Basu, P.; Oremland, R.S.; Stolz, J.F.

    2003-01-01

    The respiratory arsenate reductase from the Gram-positive, haloalkaliphile, Bacillus selenitireducens strain MLS10 was purified and characterized. It is a membrane bound heterodimer (150 kDa) composed of two subunits ArrA (110 kDa) and ArrB (34 kDa), with an apparent Km for arsenate of 34 ??M and Vmax of 2.5 ??mol min-1 mg-1. Optimal activity occurred at pH 9.5 and 150 g l-1 of NaCl. Metal analysis (inductively coupled plasma mass spectrometry) of the holoenzyme and sequence analysis of the catalytic subunit (ArrA; the gene for which was cloned and sequenced) indicate it is a member of the DMSO reductase family of molybdoproteins. ?? 2003 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

  13. Effect of impedance and higher order chromaticity on the measurement of linear chromaticity

    Energy Technology Data Exchange (ETDEWEB)

    Ranjbar, V.H.; /Tech-X, Boulder; Tan, C.Y.; /Fermilab

    2011-08-01

    The combined effect of impedance and higher order chromaticity can act on the beam in a nontrivial manner which can cause a tune shift which depends on the relative momenta with respect to the 'on momentum' particle ({Delta}p/p). Experimentally, this tune shift affects the measurement of the linear chromaticity which is traditionally measured with a change of {Delta}p/p. The theory behind this effect will be derived in this paper. Computer simulations and experimental data from the Tevatron will be used to support the theory.

  14. An Application of Chromatic Prototypes for a Universal Information System

    CERN Document Server

    McCool, Matthew

    2007-01-01

    This paper presents research on color prototypes, categories, and the neuropsychology of color. These data suggest that chromatic prototypes may be useful for thematically organizing information systems.

  15. The influence of chromatic and achromatic variability on chromatic induction and perceived colour

    NARCIS (Netherlands)

    Brenner, E; Cornelissen, FW

    2002-01-01

    Judgments of the colour of a surface are influenced by the colour of the surrounding. To determine whether only the average colour of the surrounding matters, or also the chromatic variability, judgments in colourful scenes are often compared with ones in which a target is surrounded by a plain back

  16. Reexploring the upper bound for the chromatic number of graphs

    Institute of Scientific and Technical Information of China (English)

    LI Shuchao; MAO Jingzhong

    2004-01-01

    The upper bound of the chromatic number of simple graphs is explored. Its original idea comes from Coffman, Hakimi and Schmeichel, who recently studied the chromatic number of graphs with strong conditions. In this paper, corresponding conditions are weakened and the result proves that of Ershov and Kozhukhin's.

  17. Linear and chromatic optics measurements at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Aiba, M.; Calaga, R.; Aiba, M.; Tomas, R.; Vanbavinkove, G.

    2010-05-23

    Measurements of chromatic beta-beating were carried out for the first time in the RHIC accelerator during Run 2009. The analysis package developed for the LHC was used to extract the off-momentum optics for injection and top energy. Results from the beam experiments and compassion to the optics model are presented. The primary goal of the RHIC experiments were execute an on-line measurement of the optics using the tools developed for the LHC. Turn-by-turn BPM trajectories (typically 1000 turns) acquired immediately after an external dipole kick are numerically analyzed to determine the optical parameters at the location of the beam position monitors (BPMs). For chromatic optics, a similar analysis, but on a beam with finite momentum offset(s). Each optical measurement typically is calculated from multiple data sets to capture statistical variations and ensure reproducibility. The procedure of measurement and analysis is detailed in ref [1, 2]. Two dedicated experiments were performed at RHIC with protons during Run 2009. The first at injection energy and optics and the other at 250 GeV and squeezed optics. The basic RHIC parameters relevant for the two experiments are listed in Table 1.

  18. Chromatic variations suppress suprathreshold brightness variations.

    Science.gov (United States)

    Kingdom, Frederick A A; Bell, Jason; Gheorghiu, Elena; Malkoc, Gokhan

    2010-01-01

    Most objects in natural scenes are suprathreshold in both color (chromatic) and luminance contrast. How salient is each dimension? We have developed a novel method employing a stimulus similar to that used by B. C. Regan and J. D. Mollon (1997) who studied the relative saliencies of the two chromatic cardinal directions. Our stimuli consist of left- and right-oblique modulations of color and/or luminance defined within a lattice of circles. In the "separated" condition, the two modulations were presented separately as forced-choice pairs, and the task was to indicate which was more salient. In the "combined" condition, the two orthogonal-in-orientation modulations were added, and the task was to indicate the more salient orientation. The ratio of color to luminance contrast at the PSE was calculated for both conditions. Across color directions, 48% more luminance contrast relative to color contrast was required to achieve a PSE in the "combined" compared to the "separated" condition. A second experiment showed that the PSE difference was due to the luminance being masked by the color, rather than due to superior color grouping. We conclude that suprathreshold brightness variations are masked by suprathreshold color variations. PMID:20884478

  19. Measuring aspheres with a chromatic Fizeau interferometer

    Science.gov (United States)

    Seifert, L.; Pruss, C.; Dörband, B.; Osten, W.

    2009-06-01

    The established method to measure aspherical surfaces is interferometric testing with null optics, but due to economical reasons the applications are limited. A special null optic has to be calculated, fabricated and qualified for each individual type of asphere. This time- and money consuming method is only cost-efficient for large quantities or when tests require high accuracy. We propose a new and flexible technique for measuring an ensemble of different aspheres with only one measurement setup. The main idea is to use the wavelength as a tunable parameter. Because it is possible to change the wavelength without introducing new errors by mechanical movements, the wavelength variation results in a higher measurement flexibility without reducing the measurement accuracy. We present the chromatic Fizeau Interferometer with a diffractive element as null-optic for the measurement of a set of four aspheres. We will show the influence of unwanted diffraction orders and the expected measurement accuracy. As in the monochromatic setup, especially the area around the optical axis is problematic and can not be measured with the desired accuracy. The use of a small aperture stop on the optical axis is recommended because errors in other radial domains are filtered as well. The results show, that the chromatic Fizeau interferometer makes the established monochromatic method far more flexible and that different aspheres can be measured in the same setup.

  20. On the chromatic number of general Kneser hypergraphs

    DEFF Research Database (Denmark)

    Alishahi, Meysam; Hajiabolhassan, Hossein

    2015-01-01

    In a break-through paper, Lovász [20] determined the chromatic number of Kneser graphs. This was improved by Schrijver [27], by introducing the Schrijver subgraphs of Kneser graphs and showing that their chromatic number is the same as that of Kneser graphs. Alon, Frankl, and Lovász [2] extended...... their chromatic number as an approach to a supposition of Ziegler [35] and a conjecture of Alon, Drewnowski, and Łuczak [3]. In this work, our second main result is to improve this by computing the chromatic number of a large family of Schrijver hypergraphs. Our last main result is to prove the existence...... of a completely multicolored complete bipartite graph in every coloring of a graph which extends a result of Simonyi and Tardos [29].The first two results are proved using a new improvement of the Dol'nikov-Kříž [7,18] bound on the chromatic number of general Kneser hypergraphs....

  1. Arsenate adsorption mechanisms at the allophane - Water interface

    Science.gov (United States)

    Arai, Y.; Sparks, D.L.; Davis, J.A.

    2005-01-01

    We investigated arsenate (As(V)) reactivity and surface speciation on amorphous aluminosilicate mineral (synthetic allophane) surfaces using batch adsorption experiments, powder X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The adsorption isotherm experiments indicated that As(V) uptake increased with increasing [As(V)]0 from 50 to 1000 ??M (i.e., Langmuir type adsorption isotherm) and that the total As adsorption slightly decreased with increasing NaCl concentrations from 0.01 to 0.1 M. Arsenate adsorption was initially (0-10 h) rapid followed by a slow continuum uptake, and the adsorption processes reached the steady state after 720 h. X-ray absorption spectroscopic analyses suggest that As(V) predominantly forms bidentate binuclear surface species on aluminum octahedral structures, and these species are stable up to 11 months. Solubility calculations and powder XRD analyses indicate no evidence of crystalline AI-As(V) precipitates in the experimental systems. Overall, macroscopic and spectroscopic evidence suggest that the As(V) adsorption mechanisms at the allophane-water interface are attributable to ligand exchange reactions between As(V) and surface-coordinated water molecules and hydroxyl and silicate ions. The research findings imply that dissolved tetrahedral oxyanions (e.g., H2PO42- and H2AsO42-) are readily retained on amorphous aluminosilicate minerals in aquifer and soils at near neutral pH. The innersphere adsorption mechanisms might be important in controlling dissolved arsenate and phosphate in amorphous aluminosilicate-rich low-temperature geochemical environments. ?? 2005 American Chemical Society.

  2. Comparison of arsenate and cadmium toxicity in a freshwater amphipod (Gammarus pulex)

    International Nuclear Information System (INIS)

    Cadmium is largely documented on freshwater organisms while arsenic, especially arsenate, is rarely studied. The kinetic of the LC50s values for both metals was realized on Gammarus pulex. Physiological [i.e. metal concentration in body tissues, bioconcentration factor (BCF)] effects and behavioural responses (via pleopods beats) were investigated after 240-h exposure. Arsenate LC50 value was 100 fold higher than Cd-LC50 value after 240-h exposure, while concentrations in gammarids were similar for both metals at their respective LC50s. BCF decreased with increasing cadmium concentration while BCF remained stable with increasing arsenate concentration. Moreover, BCF was between 148 and 344 times lower for arsenate than cadmium. A significant hypoventilation was observed for cadmium concentrations exceeding or close to the 240h-LC50Cd, while gammarids hyperventilated for the lowest arsenate concentrations and hypoventilated for the highest arsenate concentrations. We discussed the relationships between potential action mechanisms of these two metals and observed results. - Highlights: ► First study of arsenate toxicity in a Crustacean gammarid. ► Specific toxicological and behavioural responses to AsV and Cd contamination. ► Each metal led to specific-action mechanisms. ► Different energetic reallocation could explain specific behavioural responses. - This study brings to light the potential relationship between toxicological effects and behavioural responses of G. pulex exposed at both Cadmium and Arsenate.

  3. RATES OF HYDROUS FERRIC OXIDE CRYSTALLIZATION AND THE INFLUENCE ON COPRECIPITATED ARSENATE

    Science.gov (United States)

    Arsenate coprecipitated with hydrous ferric oxide (HFO) was stabilized against dissolution during transformation of HFO to more crystalline iron (hydr)oxides. The rate of arsenate stabilization approximately coincided with the rate of HFO transformation at pH 6 and 40 ?C. Compa...

  4. Orientation-switching transition and ferroelectricity in betaine arsenate

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, J L; Dekola, T; Vieira, L G, E-mail: jlr@fisica.uminho.p [Centro de Fisica da Universidade do Minho, Campus de Gualtar, 4715-057 Braga (Portugal)

    2009-08-12

    This paper reports a detailed investigation of the low frequency dielectric relaxation of betaine arsenate near the ferroelectric phase transition. The dielectric relaxation data are complemented with polarized infrared reflectivity data taken at low temperatures. The reported results allow us to identify several low frequency modes that clarify the complex behaviour of the dielectric response near the Curie temperature T{sub c2}{approx}120 K. It is suggested that the important slow dynamics observed is linked to the reorientation of the betaine molecular group. The roles of the different molecular units in the structural changes are briefly discussed and a new and more complex phase transition sequence is proposed.

  5. Chromatic control in coextruded layered polymer microlenses

    CERN Document Server

    Crescimanno, Michael; Andrews, James H; Zhou, Chuanhong; Petrus, Joshua B; Merlo, Cory; Bagheri, Cameron; Hetzel, Connor; Tancabel, James; Singer, Kenneth D; Baer, Eric

    2015-01-01

    We describe the formation, characterization and theoretical understanding of microlenses comprised of alternating polystyrene and polymethylmethacrylate layers produced by multilayer coextrusion. These lenses are fabricated by photolithography, using a grayscale mask followed by plasma etching, so that the refractive index alternation of the bilayer stack appears across the radius of the microlens. The alternating quarter-wave thick layers form a one-dimensional photonic crystal whose dispersion augments the material dispersion, allowing one to sculpt the chromatic dispersion of the lens by adjusting the layered structure. Using Huygen's principle, we model our experimental measurements of the focal length of these lenses across the reflection band of the multilayer polymer film from which the microlens is fashioned. For a 56 micron diameter multilayered lens of focal length 300 microns, we measured a nearly 25 percent variation in the focal length across a shallow, 50 nm-wide reflection band.

  6. Effect of radiation on hydrotalcites with chromates

    International Nuclear Information System (INIS)

    Nowadays the generation of radioactive wastes is matter of several studies. In this work anion material, chromates, in hydrotalcite are retained which are anion exchangers. It was proposed to heat the hydrotalcite until temperature of 1200 C with the purpose to form the (MgAl2O4) spinel is very stable and in this way to immobilize strongly the anions. The effect of radiation on this compound and in particular the chromium lixiviation with solution 1N NaCl. It was found that in all case, the anions are strongly retained in the spinel formed. The radiation dose used for this was 100 Mrad, the samples were treated with NaCl 1N for studying the Cr lixiviation. The results show that for the calcined samples at 1200 C and irradiated there are not chromium escapes, which indicates that it is strongly retained in the spinel that is the formed structure after of the material calcination. (Author)

  7. Advantages of chromatic-confocal spectral interferometry in comparison to chromatic confocal microscopy

    International Nuclear Information System (INIS)

    Chromatic confocal microscopy (CCM) and spectral interferometry (SI) are established and robust sensor principles. CCM is a focus-based measurement principle, whose lateral and axial resolutions depend on the sensor's numerical aperture (NA), while the measurement range is given by the spectral bandwidth and the chromatic dispersion in the axial direction. Although CCM is a robust principle, its accuracy can be reduced by self-imaging effects or asymmetric illumination of the sensor pupil. Interferometric principles based on the evaluation of the optical path difference, e.g., SI, have proven to be robust against self-imaging. The disadvantage of SI is its measurement range, which is limited by the depth of focus. Hence, the usable NA and the lateral resolution are restricted. Chromatic-confocal spectral interferometry (CCSI) is a combination of SI and CCM, which overcomes these restrictions. The increase of robustness of CCSI compared to CCM due to the interferometric gain has been demonstrated before. In this contribution the advantages of CCSI in comparison to CCM concerning self-imaging artifacts will be demonstrated. Therefore, a new phase-evaluation algorithm with higher resolution concerning classical SI-based evaluation algorithms is presented. For the comparison of different sensor systems, a chirp comparison standard is used. (paper)

  8. Photoinduced Oxidation of Arsenite to Arsenate on Ferrihydrite

    Energy Technology Data Exchange (ETDEWEB)

    N Bhandari; R Reeder; D Strongin

    2011-12-31

    The photochemistry of an aqueous suspension of the iron oxyhydroxide, ferrihydrite, in the presence of arsenite has been investigated using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray absorption near edge structure (XANES), and solution phase analysis. Both ATR-FTIR and XANES show that the exposure of ferrihydrite to arsenite in the dark leads to no change in the As oxidation state, but the exposure of this arsenite-bearing surface, which is in contact with pH 5 water, to light leads to the conversion of the majority of the adsorbed arsenite to the As(V) bearing species, arsenate. Analysis of the solution phase shows that ferrous iron is released into solution during the oxidation of arsenite. The photochemical reaction, however, shows the characteristics of a self-terminating reaction in that there is a significant suppression of this redox chemistry before 10% of the total iron making up the ferrihydrite partitions into solution as ferrous iron. The self-terminating behavior exhibited by this photochemical arsenite/ferrihydrite system is likely due to the passivation of the ferrihydrite surface by the strongly bound arsenate product.

  9. Comparative Proteomic Analysis of Rice Shoots Exposed to High Arsenate

    Institute of Scientific and Technical Information of China (English)

    Yanli Liu; Ming Li; Chao Han; Fengxia Wu; Bingkun Tu; Pingfang Yang

    2013-01-01

    Consumption of arsenic contaminated water and cereals is a serious threat to humans all over the world. Rice (Oryza sativa“Nipponbare”), as a main cereal crop, can accumulate arsenic more than 10-fold that of in other cereals. To gain a comprehensive understanding of the response of rice subjected to 100 mM arsenate stress, a comparative proteomic analysis of rice shoots in combination with morphological and biochemical investigations have been performed in this study. The results demonstrated that arsenate suppressed the growth of rice seedlings, destroyed the cellular ultra-structure and changed the homeostasis of reactive oxygen species. Moreover, a total of 38 differentially displayed proteins, which were mainly involved in metabolism, redox and protein-metabolism, were identified. The data suggest the arsenic can inhibit rice growth through negatively affecting chloroplast structure and photosynthesis. In addition, upregulation of the proteins involved in redox and protein metabolism might help the rice to be resistant or tolerant to arsenic toxicity. In general, this study improves our understanding about the rice arsenic responsive mechanism.

  10. Genetic algorithm for chromaticity correction in diffraction limited storage rings

    Science.gov (United States)

    Ehrlichman, M. P.

    2016-04-01

    A multiobjective genetic algorithm is developed for optimizing nonlinearities in diffraction limited storage rings. This algorithm determines sextupole and octupole strengths for chromaticity correction that deliver optimized dynamic aperture and beam lifetime. The algorithm makes use of dominance constraints to breed desirable properties into the early generations. The momentum aperture is optimized indirectly by constraining the chromatic tune footprint and optimizing the off-energy dynamic aperture. The result is an effective and computationally efficient technique for correcting chromaticity in a storage ring while maintaining optimal dynamic aperture and beam lifetime.

  11. Mutations affecting chromatic adaptation in the cyanobacterium Fremyella diplosiphon.

    OpenAIRE

    Cobley, J G; Miranda, R D

    1983-01-01

    The chromatically adapting cyanobacterium, Fremyella diplosiphon, when grown in cool white fluorescent light, contains phycoerythrin as its predominant phycobiliprotein. When grown on agar plates with cool white illumination, mutant colonies deficient or devoid of phycoerythrin can be visibly distinguished from the wild type. A total of 25 anomalously pigmented strains were isolated and examined for their ability to chromatically adapt. Based on absorption spectra of cell extracts and on fluo...

  12. Studies on biological reduction of chromate by Streptomyces griseus

    Energy Technology Data Exchange (ETDEWEB)

    Poopal, Ashwini C. [Division of Biochemical Sciences, National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008 (India); Laxman, R. Seeta, E-mail: rseetalaxman@yahoo.co.in [Division of Biochemical Sciences, National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008 (India)

    2009-09-30

    Chromium is a toxic heavy metal used in various industries and leads to environmental pollution due to improper handling. The most toxic form of chromium Cr(VI) can be converted to less toxic Cr(III) by reduction. Among the actinomycetes tested for chromate reduction, thirteen strains reduced Cr(VI) to Cr(III), of which one strain of Streptomyces griseus (NCIM 2020) was most efficient showing complete reduction within 24 h. The organism was able to use a number of carbon sources as electron donors. Sulphate, nitrate, chloride and carbonate had no effect on chromate reduction during growth while cations such as Cd, Ni, Co and Cu were inhibitory to varying degrees. Chromate reduction was associated with the bacterial cells and sonication was the best method of cell breakage to release the enzyme. The enzyme was constitutive and did not require presence of chromate during growth for expression of activity. Chromate reduction with cell free extract (CFE) was observed without added NADH. However, addition of NAD(P)H resulted in 2-3-fold increase in activity. Chromate reductase showed optimum activity at 28 deg. C and pH 7.

  13. Non-Chromate Passivation of Zinc

    DEFF Research Database (Denmark)

    Tang, Peter Torben; Bech-Nielsen, G.

    1993-01-01

    After extensive research and development a method for passivation of electroplated zinc has been optimised to provide the best corrosion resistance. This optimisation has lead to two different treatments both based on mo-lybdate and phosphate (from this point forward referred to as MolyPhos). The......After extensive research and development a method for passivation of electroplated zinc has been optimised to provide the best corrosion resistance. This optimisation has lead to two different treatments both based on mo-lybdate and phosphate (from this point forward referred to as Moly......Phos). The treatments are within the same concentration region, and they have a mutual pat-ent pending. Although some tests still need to be conducted, the following aspects are clear at the present time: The general appearance of the passivated zinc surface is very similar to a standard yellow chromate treatment....... There is no known environmental or health risk involved using the treatments mentioned above. All components used in the baths are non toxic compared to Cr(VI). Alloy coatings such as zinc/nickel, zinc/cobalt, zinc/tin and all types of pure zinc coating (from cyanide, acidic or alkaline baths) have been treated...

  14. Is accommodation colorblind? Focusing chromatic contours.

    Science.gov (United States)

    Wolfe, J M; Owens, D A

    1981-01-01

    Two adjacent regions define an edge if they differ in either color or luminance. If the difference is purely chromatic, the edge is said to be isoluminant. Isoluminant contours are often perceptually unstable. Perhaps some of this instability could be explained if isoluminant contours were difficult to bring into focus. To test this hypothesis, a vernier optometer was used to measure the accuracy of steady-state accommodation for the vertical boundary of a red-green bipartite field. This edge was presented at optical distances of 0, 1.5, 3.0, and 4.5 diopters, with brightness contrasts between the two hemifields of 0% (isoluminant), 15%, 58%, and 100%. Accommodation was essentially unresponsiveness to the isoluminant edge and exhibited increasing focusing accuracy with increased brightness contrast. Control experiments replicated this finding for red-orange, green-blue, and white-white fields. These results imply that luminance contrast is a necessary stimulus for monocular accommodation. Inappropriate accommodation may be a factor contributing to the perceptual instability of isoluminant patterns. PMID:7255083

  15. An alternate pathway of arsenate resistance in E. coli mediated by the glutathione S-transferase GstB.

    Science.gov (United States)

    Chrysostomou, Constantine; Quandt, Erik M; Marshall, Nicholas M; Stone, Everett; Georgiou, George

    2015-03-20

    Microbial arsenate resistance is known to be conferred by specialized oxidoreductase enzymes termed arsenate reductases. We carried out a genetic selection on media supplemented with sodium arsenate for multicopy genes that can confer growth to E. coli mutant cells lacking the gene for arsenate reductase (E. coli ΔarsC). We found that overexpression of glutathione S-transferase B (GstB) complemented the ΔarsC allele and conferred growth on media containing up to 5 mM sodium arsenate. Interestingly, unlike wild type E. coli arsenate reductase, arsenate resistance via GstB was not dependent on reducing equivalents provided by glutaredoxins or a catalytic cysteine residue. Instead, two arginine residues, which presumably coordinate the arsenate substrate within the electrophilic binding site of GstB, were found to be critical for transferase activity. We provide biochemical evidence that GstB acts to directly reduce arsenate to arsenite with reduced glutathione (GSH) as the electron donor. Our results reveal a pathway for the detoxification of arsenate in bacteria that hinges on a previously undescribed function of a bacterial glutathione S-transferase.

  16. Arsenate tolerance in Silene paradoxa does not rely on phytochelatin-dependent sequestration.

    Science.gov (United States)

    Arnetoli, Miluscia; Vooijs, Riet; ten Bookum, Wilma; Galardi, Francesca; Gonnelli, Cristina; Gabbrielli, Roberto; Schat, Henk; Verkleij, Jos A C

    2008-04-01

    Arsenate tolerance, As accumulation and As-induced phytochelatin accumulation were compared in populations of Silene paradoxa, one from a mine site enriched in As, Cu and Zn, the other from an uncontaminated site. The mine population was significantly more arsenate-tolerant. Arsenate uptake and root-to-shoot transport were slightly but significantly higher in the non-mine plants. The difference in uptake was quantitatively insufficient to explain the difference in tolerance between the populations. As accumulation in the roots was similar in both populations, but the mine plants accumulated much less phytochelatins than the non-mine plants. The mean phytochelatin chain length, however, was higher in the mine population, possibly due to a constitutively lower cellular glutathione level. It is argued that the mine plants must possess an arsenic detoxification mechanism other than arsenate reduction and subsequent phytochelatin-based sequestration. This alternative mechanism might explain at least some part of the superior tolerance in the mine plants.

  17. Two Lactococcus lactis thioredoxin paralogues play different roles in responses to arsenate and oxidative stress

    DEFF Research Database (Denmark)

    Efler, Petr; Kilstrup, Mogens; Johnsen, Stig;

    2015-01-01

    Thioredoxin (Trx) maintains intracellular thiol groups in a reduced state and is involved in a wide range of cellular processes, including ribonucleotide reduction, sulphur assimilation, oxidative stress responses and arsenate detoxification. The industrially important lactic acid bacterium Lacto...

  18. Arsenate adsorption and desorption kinetics on a Fe(III)-modified montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Luengo, Carina; Puccia, Virginia [INQUISUR, Departamento de Quimica, Universidad Nacional del Sur, Bahia Blanca (Argentina); Avena, Marcelo, E-mail: mavena@uns.edu.ar [INQUISUR, Departamento de Quimica, Universidad Nacional del Sur, Bahia Blanca (Argentina); Consejo de Investigaciones Cientificas y Tecnicas de Argentina (CONICET) (Argentina)

    2011-02-28

    Graphical abstract: Arsenate adsorption is much higher in Fe-exchanged montmorillonite (Fe-M) than in Na-exchanged montmorillonite (Na-M). The adsorption takes place in a two-step mechanism. Research highlights: {yields} Adsorption-desorption kinetics of arsenate on a Fe(III)-modified montmorillonite is reported. {yields} Fe(III) species are the responsible for arsenate adsorption. {yields} The adsorption takes place in a two-step mechanism. {yields} Adsorption and desorption studies reflect the presence of externally and internally adsorbed arsenate. {yields} Fe(III) species in Fe-M are more efficient in binding arsenate than in ferrihydrite or goethite. - Abstract: The adsorption-desorption kinetics of arsenate on a Fe(III)-modified montmorillonite (Fe-M) was studied at different arsenate concentrations, pH and stirring rates. The synthesized solid was a porous sample with Fe(III) present as a mix of monomeric and polymeric Fe(III) species in the interlayer and on the external surface. Adsorption took place in a two-step mechanism, with an initial fast binding of arsenate to Fe(III) species at the external surface (half-lives of 1 min or shorter) followed by a slower binding to less accessible Fe(III) species in pores and the interlayer (half-lives of around 1 h). Desorption kinetics also reflected the presence of externally and internally adsorbed arsenate. At pH 6 the maximum adsorbed arsenate was 52 {mu}mol/g, a value that is low as compared to adsorption on ferrihydrite (700 {mu}mol/g) and goethite (192-220 {mu}mol/g). However, since the Fe(III) content of Fe-M is much lower than that of ferrihydrite and goethite, Fe(III) species in Fe-M are more efficient in binding arsenate than in ferrihydrite or goethite (one As atom is attached every 8.95 iron atoms). This high binding efficiency indicates that Fe(III) species are well spread on montmorillonite, forming small oligomeric species or surface clusters containing just a few iron atoms.

  19. Characterization of microbial arsenate reduction in the anoxic bottom waters of Mono Lake, California

    Science.gov (United States)

    Hoeft, S.E.; Lucas, F.; Hollibaugh, J.T.; Oremland, R.S.

    2002-01-01

    Dissimilatory reduction of arsenate (DAsR) occurs in the arsenic-rich, anoxic water column of Mono Lake, California, yet the microorganisms responsible for this observed in situ activity have not been identified. To gain insight as to which microorganisms mediate this phenomenon, as well as to some of the biogeochemical constraints on this activity, we conducted incubations of arsenate-enriched bottom water coupled with inhibition/amendment studies and Denaturing Gradient Gel Electrophoresis (DGGE) characterization techniques. DAsR was totally inhibited by filter-sterilization and by nitrate, partially inhibited (~50%) by selenate, but only slightly (~25%) inhibited by oxyanions that block sulfate-reduction (molybdate and tungstate). The apparent inhibition by nitrate, however, was not due to action as a preferred electron acceptor to arsenate. Rather, nitrate addition caused a rapid, microbial re-oxidation of arsenite to arsenate, which gave the overall appearance of no arsenate loss. A similar microbial oxidation of As(III) was also found with Fe(III), a fact that has implications for the recycling of As(V) in Mono Lake's anoxic bottom waters. DAsR could be slightly (10%) stimulated by substrate amendments of lactate, succinate, malate, or glucose, but not by acetate, suggesting that the DAsR microflora is not electron donor limited. DGGE analysis of amplified 16S rDNA gene fragments from incubated arsenate-enriched bottom waters revealed the presence of two bands that were not present in controls without added arsenate. The resolved sequences of these excised bands indicated the presence of members of the epsilon (Sulfurospirillum) and delta (Desulfovibrio) subgroups of the Proteobacteria, both of which have representative species that are capable of anaerobic growth using arsenate as their electron acceptor.

  20. Behavior of Eucalyptus urophylla and Eucalyptus citriodora Seedlings Grown in Soil Contaminated by Arsenate

    OpenAIRE

    Roseli Freire de Melo; Luiz Eduardo Dias; Igor Rodrigues de Assis

    2016-01-01

    ABSTRACT Persistent areas of tailings and deposits from coal and gold mining may present high levels of arsenic (As), mainly in the arsenate form, endangering the environment and human health. The establishment of vegetation cover is a key step to reclaiming these environments. Thus, this study aimed to evaluate the potential of Eucalyptus urophylla and E. citriodora seedlings for use in phytoremediation programs of arsenate-contaminated areas. Soil samples were incubated at increasing rates ...

  1. Evidence for the aquatic binding of arsenate by natural organic matter-suspended Fe(III)

    Science.gov (United States)

    Ritter, K.; Aiken, G.R.; Ranville, J.F.; Bauer, M. E.; Macalady, D.L.

    2006-01-01

    Dialysis experiments with arsenate and three different NOM samples amended with Fe(III) showed evidence confirming the formation of aquatic arsenate-Fe(III)-NOM associations. A linear relationship was observed between the amount of complexed arsenate and the Fe(III) content of the NOM. The dialysis results were consistent with complex formation through ferric iron cations acting as bridges between the negatively charged arsenate and NOM functional groups and/or a more colloidal association, in which the arsenate is bound by suspended Fe(III)-NOM colloids. Sequential filtration experiments confirmed that a significant proportion of the iron present at all Fe/C ratios used in the dialysis experiments was colloidal in nature. These colloids may include larger NOM species that are coagulated by the presence of chelated Fe(III) and/or NOM-stabilized ferric (oxy)hydroxide colloids, and thus, the solution-phase arsenate-Fe(III)-NOM associations are at least partially colloidal in nature. ?? 2006 American Chemical Society.

  2. A mechanistic study of arsenate removal from artificially contaminated clay soils by electrokinetic remediation.

    Science.gov (United States)

    Suzuki, Tasuma; Moribe, Mai; Okabe, Yohhei; Niinae, Masakazu

    2013-06-15

    Batch desorption experiments and bench-scale electrokinetic experiments were performed to elucidate the electrokinetic remediation mechanisms of arsenate from artificially contaminated kaolinite. The electrokinetic experiments in which a constant voltage was applied demonstrated that high soil pH favored arsenate remediation with respect to both the remediation time and electricity consumption. It was also demonstrated that applying a pulse voltage (1 h ON, 1 h OFF) significantly improved the electricity consumption efficiency when the soil pH was maintained at the initial value during the experiments; this trend was not observed when the soil pH was gradually increased from the cathode side. These electrokinetic experimental results, with the support of arsenate desorption data obtained from batch experiments, indicate that the remediation rate-limiting step varied with soil pH. When the soil pH was maintained at the initial value of 7.2 during the experiments, arsenate desorption was the remediation rate-limiting step rather than the migration of dissolved arsenate toward the anode. Conversely, when the cathode pH was not controlled and the soil pH was correspondingly increased gradually from the cathode side, the migration of hydroxyl and desorbed arsenate ions toward the anode played a more important role in the control of the overall remediation efficiency. PMID:23643955

  3. Bovine arsenic toxicosis from ingestion of ashed copper-chrome-arsenate treated timber.

    Science.gov (United States)

    Hullinger, G; Sangster, L; Colvin, B; Frazier, K

    1998-06-01

    Arsenic toxicosis is reported in a variety of animal species. It occurs most commonly in cattle and ranks second only to lead as a cause of heavy metal poisoning. We describe a case of arsenic toxicosis attributable to ingestion of ashes from burned posts treated with an arsenic-containing preservative. Burning of the posts concentrated the arsenic and rendered lethal a product normally used around livestock. Lack of normal salt supplementation to the herd was conducive to pica-like behavior and ingestion of toxic ashes. Rapid diagnosis led to removal of the arsenic source and limited losses to 4 cows.

  4. Chromatically unique 6-bridge graph theta(a,a,a,b,b,c

    Directory of Open Access Journals (Sweden)

    N.S.A. Karim

    2016-04-01

    Full Text Available For a graph $G$, let $P(G,\\lambda$ denote the chromatic polynomial of $G$. Two graphs $G$ and $H$ are chromatically equivalent if they share the same chromatic polynomial. A graph $G$ is chromatically unique if for any graph chromatically equivalent to $G$ is isomorphic to $G$. In this paper, the chromatically unique of a new family of 6-bridge graph $\\theta(a,a,a,b,b,c$ where $2\\le a\\le b\\le c$ is investigated.

  5. Copper transport.

    Science.gov (United States)

    Linder, M C; Wooten, L; Cerveza, P; Cotton, S; Shulze, R; Lomeli, N

    1998-05-01

    In adult humans, the net absorption of dietary copper is approximately 1 mg/d. Dietary copper joins some 4-5 mg of endogenous copper flowing into the gastrointestinal tract through various digestive juices. Most of this copper returns to the circulation and to the tissues (including liver) that formed them. Much lower amounts of copper flow into and out of other major parts of the body (including heart, skeletal muscle, and brain). Newly absorbed copper is transported to body tissues in two phases, borne primarily by plasma protein carriers (albumin, transcuprein, and ceruloplasmin). In the first phase, copper goes from the intestine to the liver and kidney; in the second phase, copper usually goes from the liver (and perhaps also the kidney) to other organs. Ceruloplasmin plays a role in this second phase. Alternatively, liver copper can also exit via the bile, and in a form that is less easily reabsorbed. Copper is also present in and transported by other body fluids, including those bathing the brain and central nervous system and surrounding the fetus in the amniotic sac. Ceruloplasmin is present in these fluids and may also be involved in copper transport there. The concentrations of copper and ceruloplasmin in milk vary with lactational stage. Parallel changes occur in ceruloplasmin messenger RNA expression in the mammary gland (as determined in pigs). Copper in milk ceruloplasmin appears to be particularly available for absorption, at least in rats.

  6. Copper transport.

    Science.gov (United States)

    Linder, M C; Wooten, L; Cerveza, P; Cotton, S; Shulze, R; Lomeli, N

    1998-05-01

    In adult humans, the net absorption of dietary copper is approximately 1 mg/d. Dietary copper joins some 4-5 mg of endogenous copper flowing into the gastrointestinal tract through various digestive juices. Most of this copper returns to the circulation and to the tissues (including liver) that formed them. Much lower amounts of copper flow into and out of other major parts of the body (including heart, skeletal muscle, and brain). Newly absorbed copper is transported to body tissues in two phases, borne primarily by plasma protein carriers (albumin, transcuprein, and ceruloplasmin). In the first phase, copper goes from the intestine to the liver and kidney; in the second phase, copper usually goes from the liver (and perhaps also the kidney) to other organs. Ceruloplasmin plays a role in this second phase. Alternatively, liver copper can also exit via the bile, and in a form that is less easily reabsorbed. Copper is also present in and transported by other body fluids, including those bathing the brain and central nervous system and surrounding the fetus in the amniotic sac. Ceruloplasmin is present in these fluids and may also be involved in copper transport there. The concentrations of copper and ceruloplasmin in milk vary with lactational stage. Parallel changes occur in ceruloplasmin messenger RNA expression in the mammary gland (as determined in pigs). Copper in milk ceruloplasmin appears to be particularly available for absorption, at least in rats. PMID:9587137

  7. Copper hypersensitivity

    DEFF Research Database (Denmark)

    Fage, Simon W; Faurschou, Annesofie; Thyssen, Jacob P

    2014-01-01

    The world production of copper is steadily increasing. Although humans are widely exposed to copper-containing items on the skin and mucosa, allergic reactions to copper are only infrequently reported. To review the chemistry, biology and accessible data to clarify the implications of copper...... hypersensitivity, a database search of PubMed was performed with the following terms: copper, dermatitis, allergic contact dermatitis, contact hypersensitivity, contact sensitization, contact allergy, patch test, dental, IUD, epidemiology, clinical, and experimental. Human exposure to copper is relatively common....... As a metal, it possesses many of the same qualities as nickel, which is a known strong sensitizer. Cumulative data on subjects with presumed related symptoms and/or suspected exposure showed that a weighted average of 3.8% had a positive patch test reaction to copper. We conclude that copper is a very weak...

  8. Competitive adsorption of arsenate and phosphate onto calcite; experimental results and modeling with CCM and CD-MUSIC

    DEFF Research Database (Denmark)

    Sø, Helle Ugilt; Postma, Dieke; Jakobsen, Rasmus;

    2012-01-01

    The competitive adsorption of arsenate and phosphate onto calcite was studied in batch experiments using calcite-equilibrated solutions. The solutions had circum-neutral pH (7–8.3) and covered a wide span in the activity of Ca2+ and View the MathML source. The results show that the adsorption...... that adsorption of arsenate onto calcite is of minor importance in most groundwater aquifers, as phosphate is often present at concentration levels sufficient to significantly reduce arsenate adsorption. The CD-MUSIC model for calcite was used successfully to model adsorption of arsenate and phosphate separately...

  9. Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenate

    Science.gov (United States)

    Waychunas, G. A.; Rea, B. A.; Fuller, C. C.; Davis, J. A.

    1993-05-01

    EXAFS spectra were collected on both the As and Fe K-edges from samples of two-line ferrihydrite with adsorbed (ADS) and coprecipitated (CPT) arsenate prepared over a range of conditions and arsenate surface coverages. Spectra also were collected for arsenate adsorbed on the surfaces of three FeOOH crystalline polymorphs, α (goethite), β (akaganeite), and γ (lepidocrocite), and as a free ion in aqueous: solution. Analyses of the As EXAFS show clear evidence for inner sphere bidentate (bridging) arsenate complexes on the ferrihydrite surface and on the surfaces of the crystalline FeOOH polymorphs. The bridging arsenate is attached to adjacent apices of edge-sharing Fe oxyhydroxyl octahedra. The arsenic-iron distance at the interface ( 3.28 ±0.01 Å) is close to that expected for this geometry on the FeOOH polymorph surfaces, but is slightly shorter on the ferrihydrite surfaces ( 3.25 ± 0.02 Å). Mono-dentate arsenate linkages ( 3.60 ± 0.03 Å) also occur on the ferrihydrite, but are not generally observed on the crystalline FeOOH polymorphs. The proportion of monodentate bonds appears largest for adsorption samples with the smallest As/Fe molar ratio. In all cases the arsenate tetrahedral complex is relatively undistorted with As-O bonds of 1.66 ± 0.01 Å. Precipitation of arsenate or scorodite-like phases was not observed for any samples, all of which were prepared at a pH value of 8. The Fe EXAFS results confirm that the Fe-Fe correlations in the ferrihydrite are progressively disrupted in the CPT samples as the As/Fe ratio is increased. Coherent crystallite size is probably no more than 10 Å in diameter and no Fe oxyhydroxyl octahedra corner-sharing linkages (as would be present in FeOOH polymorphs) are observed at the largest As/Fe ratios. Comparison of the number and type of Fe-Fe neighbors with the topological constraints imposed by the arsenate saturation limit in the CPT samples (about 0.7 As/Fe) indicates ferrihydrite units consisting mainly of Fe

  10. Surface chemistry of ferrihydrite: Part 1. EXAFS studies of the geometry of coprecipitated and adsorbed arsenate

    Science.gov (United States)

    Waychunas, G.A.; Rea, B.A.; Fuller, C.C.; Davis, J.A.

    1993-01-01

    EXAFS spectra were collected on both the As and Fe K-edges from samples of two-line ferrihydrite with adsorbed (ADS) and coprecipitated (CPT) arsenate prepared over a range of conditions and arsenate surface coverages. Spectra also were collected for arsenate adsorbed on the surfaces of three FeOOH crystalline polymorphs, ?? (goethite), ?? (akaganeite), and ?? (lepidocrocite), and as a free ion in aqueous: solution. Analyses of the As EXAFS show clear evidence for inner sphere bidentate (bridging) arsenate complexes on the ferrihydrite surface and on the surfaces of the crystalline FeOOH polymorphs. The bridging arsenate is attached to adjacent apices of edge-sharing Fe oxyhydroxyl octahedra. The arsenic-iron distance at the interface (3.28 ??0.01 A ??) is close to that expected for this geometry on the FeOOH polymorph surfaces, but is slightly shorter on the ferrihydrite surfaces (3.25 ?? 0.02 A ??). Mono-dentate arsenate linkages (3.60 ?? 0.03 A ??) also occur on the ferrihydrite, but are not generally observed on the crystalline FeOOH polymorphs. The proportion of monodentate bonds appears largest for adsorption samples with the smallest As Fe molar ratio. In all cases the arsenate tetrahedral complex is relatively undistorted with As-O bonds of 1.66 ?? 0.01 A ??. Precipitation of arsenate or scorodite-like phases was not observed for any samples, all of which were prepared at a pH value of 8. The Fe EXAFS results confirm that the Fe-Fe correlations in the ferrihydrite are progressively disrupted in the CPT samples as the As Fe ratio is increased. Coherent crystallite size is probably no more than 10 A?? in diameter and no Fe oxyhydroxyl octahedra corner-sharing linkages (as would be present in FeOOH polymorphs) are observed at the largest As Fe ratios. Comparison of the number and type of Fe-Fe neighbors with the topological constraints imposed by the arsenate saturation limit in the CPT samples (about 0.7 As Fe) indicates ferrihydrite units consisting mainly

  11. Correcting the Chromatic Aberration in Barrel Distortion of Endoscopic Images

    Directory of Open Access Journals (Sweden)

    Y. M. Harry Ng

    2003-04-01

    Full Text Available Modern endoscopes offer physicians a wide-angle field of view (FOV for minimally invasive therapies. However, the high level of barrel distortion may prevent accurate perception of image. Fortunately, this kind of distortion may be corrected by digital image processing. In this paper we investigate the chromatic aberrations in the barrel distortion of endoscopic images. In the past, chromatic aberration in endoscopes is corrected by achromatic lenses or active lens control. In contrast, we take a computational approach by modifying the concept of image warping and the existing barrel distortion correction algorithm to tackle the chromatic aberration problem. In addition, an error function for the determination of the level of centroid coincidence is proposed. Simulation and experimental results confirm the effectiveness of our method.

  12. Particle motion onto a synchrotron chromatic closed orbit

    International Nuclear Information System (INIS)

    This work aims at establishing the analytical expressions used in the code BETA characterizing the motion of particles onto a closed chromatic orbit in a synchrotron. It presents thoroughly the calculations effected some ten years ago but not published so far. The formalism used is the one of second-order aberrations developed for the code TRANSPORT. It leads to expressions for the second-order dispersion function, first-order chromaticities and the second-order momentum compaction as a function of the second-order transfer matrix elements. Moreover, this approach allows obtaining the explicit analytical expression of the second-order momentum compaction. In conclusion, by means of the formalism of second-order aberrations one obtains the analytical expressions for characterizing the behaviour of the beams presenting momentum dispersion, up to first or second order in δ. Minimizing of the chromatic perturbations implies then minimizing the second-order matrix elements Tijk interrelated by symplecticity conditions

  13. ars1, an Arabidopsis mutant exhibiting increased tolerance to arsenate and increased phosphate uptake.

    Science.gov (United States)

    Lee, David A; Chen, Alice; Schroeder, Julian I

    2003-09-01

    Arsenic is one of the most toxic pollutants at contaminated sites, yet little is known about the mechanisms by which certain plants survive exposure to high arsenic levels. To gain insight into the mechanisms of arsenic tolerance in plants, we developed a genetic screen to isolate Arabidopsis thaliana mutants with altered tolerance to arsenic. We report here on the isolation of a mutant arsenic resisant 1 (ars1) with increased tolerance to arsenate. ars1 germinates and develops under conditions that completely inhibit growth of wild-type plants and shows a semi-dominant arsenic resistance phenotype. ars1 accumulates levels of arsenic similar to that accumulated by wild-type plants, suggesting that ars1 plants have an increased ability to detoxify arsenate. However, ars1 plants produce phytochelatin levels similar to levels produced by the wild type, and the enhanced resistance of ars1 is not abolished by the gamma-glutamylcysteine synthetase inhibitor l-buthionine sulfoxime (BSO). Furthermore, ars1 plants do not show resistance to arsenite or other toxic metals such as cadmium and chromium. However, ars1 plants do show a higher rate of phosphate uptake than that shown by wild-type plants, and wild-type plants grown with an excess of phosphate show increased tolerance to arsenate. Traditional models of arsenate tolerance in plants are based on the suppression of phosphate uptake pathways and consequently on the reduced uptake of arsenate. Our data suggest that arsenate tolerance in ars1 could be due to a new mechanism mediated by increased phosphate uptake in ars1. Models discussing how increased phosphate uptake could contribute to arsenate tolerance are discussed.

  14. The Pho4 transcription factor mediates the response to arsenate and arsenite in Candida albicans.

    Science.gov (United States)

    Urrialde, Verónica; Prieto, Daniel; Pla, Jesús; Alonso-Monge, Rebeca

    2015-01-01

    Arsenate (As (V)) is the dominant form of the toxic metalloid arsenic (As). Microorganisms have consequently developed mechanisms to detoxify and tolerate this kind of compounds. In the present work, we have explored the arsenate sensing and signaling mechanisms in the pathogenic fungus Candida albicans. Although mutants impaired in the Hog1 or Mkc1-mediated pathways did not show significant sensitivity to this compound, both Hog1 and Mkc1 became phosphorylated upon addition of sodium arsenate to growing cells. Hog1 phosphorylation upon arsenate challenge was shown to be Ssk1-dependent. A screening designed for the identification of transcription factors involved in the arsenate response identified Pho4, a transcription factor of the myc-family, as pho4 mutants were susceptible to As (V). The expression of PHO4 was shortly induced in the presence of sodium arsenate in a Hog1-independent manner. Pho4 level affects Hog1 phosphorylation upon As (V) challenge, suggesting an indirect relationship between Pho4 activity and signaling in C. albicans. Pho4 also mediates the response to arsenite as revealed by the fact that pho4 defective mutants are sensitive to arsenite and Pho4 becomes phosphorylated upon sodium arsenite addition. Arsenite also triggers Hog1 phosphorylation by a process that is, in this case, independent of the Ssk1 kinase. These results indicate that the HOG pathway mediates the response to arsenate and arsenite in C. albicans and that the Pho4 transcription factor can differentiate among As (III), As (V) and Pi, triggering presumably specific responses. PMID:25717325

  15. Vibrio harveyi Nitroreductase Is Also a Chromate Reductase

    OpenAIRE

    Kwak, Young Hak; Lee, Dong Seok; Kim, Han Bok

    2003-01-01

    The chromate reductase purified from Pseudomonas ambigua was found to be homologous with several nitroreductases. Escherichia coli DH5α and Vibrio harveyi KCTC 2720 nitroreductases were chosen for the present study, and their chromate-reducing activities were determined. A fusion between glutathione S-transferase (GST) and E. coli DH5α NfsA (GST-EcNfsA), a fusion between GST and E. coli DH5α NfsB (GST-EcNfsB), and a fusion between GST and V. harveyi KCTC 2720 NfsA (GST-VhNfsA) were prepared f...

  16. Ultrafast spatiotemporal laser pulse engineering using chromatic dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Li Yuelin; Chemerisov, Sergey [Argonne National Laboratory, Argonne, IL 60439 (United States); Shen Baifei, E-mail: ylli@aps.anl.gov [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, PO Box 800-211, Shanghai 201800 (China)

    2010-12-15

    We discuss a new method for manipulating the optical field distribution in time and space at the focal plane of a chromatic lens. Chromatic dispersion and aberration make it possible to control the photon distribution in both time and space by properly controlling the amplitude and phase of the incident laser pulse, including shortening a laser pulse or generating a specific time-dependent transverse distribution. As an example, we discuss the generation of a quasi-three-dimensional ellipsoidal photon distribution and a proof-of-principle experiment, where favourable agreement between theoretical calculations and the data is observed.

  17. Vertex Distinguishing Equitable Total Chromatic Number of Join Graph

    Institute of Scientific and Technical Information of China (English)

    Zhi-wen Wang; Li-hong Yan; Zhong-fu Zhang

    2007-01-01

    A vertex distinguishing equitable total coloring of graph G is a proper total coloring of graph G such that any two distinct vertices' coloring sets are not identical and the difference of the elements colored by any two colors is not more than 1. In this paper we shall give vertex distinguishing equitable total chromatic number of join graphs Pn∨Pn, Cn∨Cn, and prove that they satisfy conjecture 3, namely, the chromatic numbers of vertex distinguishing total and vertex distinguishing equitable total are the same for join graphs Pn∨Pn and Cn∨Cn.

  18. Adsorption of arsenate on Cu/Mg/Fe/La layered double hydroxide from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yanwei [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Zhu, Zhiliang, E-mail: zzl@tongji.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Qiu, Yanling [Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, Shanghai 200092 (China); Zhao, Jianfu [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer A novel layered double hydroxide containing lanthanum (Cu/Mg/Fe/La-LDH) has been synthesized. Black-Right-Pointing-Pointer The average pore size of the materials with about 16 nm indicated that the mesoporous structures existed in the Cu/Mg/Fe/La-LDHs. Black-Right-Pointing-Pointer The adsorption capacity of As(V) increased with the increment of La{sup 3+} content in the LDH. Black-Right-Pointing-Pointer The maximum adsorption capacity of the synthesized Cu/Mg/Fe/La-LDH for arsenate was 43.5 mg/g. - Abstract: A novel layered double hydroxide containing lanthanum (Cu/Mg/Fe/La-LDH) has been synthesized and used for the removal of arsenate from aqueous solutions. The purpose of incorporation of La{sup 3+} into LDHs was tried to enhance the uptake efficiency of arsenate and broaden the application field of LDHs functional materials. Effects of various physico-chemical factors such as solution pH, adsorbent dosage, contact time and initial arsenate concentrations on the adsorption of arsenate onto Cu/Mg/Fe/La-LDH were investigated. Results showed that the removal efficiency of arsenate increased with the increment of the lanthanum content in Cu/Mg/Fe/La-LDH adsorbents, and the optimized lanthanum content was 20% of the total trivalent metals composition (Fe{sup 3+} and La{sup 3+}). The adsorption isotherms can be well described by Langmuir equation, and the adsorption kinetics of arsenate followed the pseudo-second-order kinetic model. Coexistent ions such as HPO{sub 4}{sup 2-}, CO{sub 3}{sup 2-}, SO{sub 4}{sup 2-}, Cl{sup -} and NO{sub 3}{sup -} exhibited obvious competition with arsenate for the adsorption on Cu/Mg/Fe/La-LDH. The solution pH significantly affected the removal efficiency, which was closely related to the change of arsenate species distribution under different pH conditions. The predominant adsorption mechanism can be mainly attributed to the processes including ion exchange and layer ligand exchange.

  19. Closure plan for the Test Area North-726 chromate water storage and Test Area North-726A chromate treatment units

    International Nuclear Information System (INIS)

    This document describes the proposed plan for closure of the Test Area North-726 chromate water storage and Test Area North-726A chromate treatment units at the Idaho National Engineering Laboratory in accordance with the Resource Conservation and Recovery Act interim status closure requirements. The location, size, capacity, and history of the units are described, and their current status is discussed. The units will be closed by treating remaining waste in storage, followed by thorough decontamination of the systems. Sufficient sampling and analysis, and documentation of all activities will be performed to demonstrate clean closure

  20. Determinants Encoding Resistance to Several Heavy Metals in Newly Isolated Copper-Resistant Bacteria

    OpenAIRE

    Dressler, Cathrin; Kües, Ursula; Nies, Dietrich H.; Friedrich, Bärbel

    1991-01-01

    Three copper-resistant, gram-negative bacteria were isolated and characterized. Of the three strains, Alcaligenes denitrificans AH tolerated the highest copper concentration (MIC = 4 mM CuSO4). All three strains showed various levels of resistance to other metal ions. A. denitrificans AH contains sequences which cross-hybridized with the mer (mercury resistance) determinant of Tn21 and the czc (cobalt, zinc, and cadmium resistance), cnr (cobalt and nickel resistance), and chr (chromate resist...

  1. Utilization of activated CO2-neutralized red mud for removal of arsenate from aqueous solutions.

    Science.gov (United States)

    Sahu, Ramesh Chandra; Patel, Rajkishore; Ray, Bankim Chandra

    2010-07-15

    A laboratory study was conducted to investigate the ability of activated CO(2)-neutralized red mud (ANRM) for the removal of arsenate from the aqueous solutions. The batch adsorption experiments were conducted with respect to adsorbent dose, equilibrium pH, contact time, initial arsenate concentration, kinetics, Langmuir isotherms. The mechanisms involved in adsorption of arsenate ions on ANRM were characterized by using XRD, FT-IR, UV-vis, SEM/EDX, and chemical methods. The percentage removal was found to increase gradually with decrease of pH and maximum removal was achieved at pH approximately 4. Adsorption kinetic studies revealed that the adsorption process followed pseudo-second-order kinetics and equilibrates within 24 h. FT-IR spectra of ANRM before and after adsorption reveals the binding of arsenate to the adsorbent. The adsorption data were fitted to linearly transformed Langmuir isotherm with R(2) (correlation coefficient)>0.99. Arsenate adsorbed ANRM can be regenerated using NaOH solution at pH 12.0.

  2. Localization of the Dissimilatory Arsenate Reductase in Sulfurospirillum Barnesi Strain SeS-3

    Directory of Open Access Journals (Sweden)

    Eman Afkar

    2012-01-01

    Full Text Available Problem statement: Sulfurospirillim barnesii strain SeS-3 is one of the recently known bacterial isolates that can obtain energy to support growth by respiring the toxic oxyanions of arsenic and selenium under anaerobic conditions. Approach: The ultimate goal of this investigation is to localize the active sites for the reduction of arsenate arsenite as well as selenate selenite in S. barnesii strain SeS-3. Results: The ability of the type strain Sulfurospirillium barnesii strain SES-3 (ATCC 700032 to reduce selenate and arsenate were tested using cell grown anaerobically with 20 mM lactate as the carbon source and either 10 mM selenate or 5 mM arsenate as the terminal electron acceptors were harvested after the turbidity reached 0.3, 0.4 absorption units at 600 nm, cell density 4gm wet cells. The results of this study showed that the mobilization of the toxic oxyanions of arsenic and selenium by Sulfurospirillum barnesii strain SES-3 is linked to the membrane. The enzyme is specific for the reduction of arsenate, selenate, selenite, nitrite, thiosulfate and phosphate. Whereas, no specificity was detected for arsenite nitrate, fumarate, when they served as the final electron acceptor. Conclusion/Recommendations: This study concluded that the mechanism of arsenate reduction by S.barnesii strain SeS-3 is connected into the membrane. The environmental significance of this bacterium and its impact to the bioremediation potential in the underground water and sedimentary environment is also discussed.

  3. To question about theory chromatic light paint

    Science.gov (United States)

    Vozchikov, Lev M.

    2002-06-01

    When we give name to color, we usually describe our perception of light, as compared with our own experience and knowledge. Very often perception of color is a complex problem that needs to be described by mathematical, physiological, and physical theories. There is a clear description for the physical task of describing quantities for mixing color pigments. In this article, the author discussed original graphical decision for color equations: the color surface for natural mixtures. Light mixing theories describe the nature of color, originally in mathematical language of the physical principles for color mixing different substances. Color-mixing system were originally developed based on the three-component chromatic model, which tells us how color works in nature and how color mixing works with pigments. Color theory was developed to show how color pigment structures could be measured. In this article, an algebraic system is shown consisting of mathematical equations, given the surface of color mixing, gives measurement principles of color characteristics by the two quantities. This mathematical system has shown by graphical decision color mixing the nature of the physical 3-component vision. The original model of mixing equally well provides the numerical identification for color mixtures of two or three components pigments. Clear descriptions of colors on the color surface show the different characteristics of color, and the value that these colors have in light mixing as estimated by the vision perception system. Color surface is very important as a practical conception for understanding the quantitative description of color measurement technology. The color surface as a graphical model is mathematically necessary to describe the mixing color components of pigments, lights, and substrates. Each single color is positioned as a sum of several primary colors and can be applied in the separate physical task of measuring color, to reproduce color by technology

  4. Totally odd K-4-subdivisions in 4-chromatic graphs

    DEFF Research Database (Denmark)

    Thomassen, Carsten

    2001-01-01

    We prove the conjecture made by Bjarne Toft in 1975 that every 4-chromatic graph contains a subdivision of K-4 in which each edge of K-4 corresponds to a path of odd length. As an auxiliary result we characterize completely the subspace of the cycle space generated by all cycles through two fixed...

  5. CHROMATIC NUMBER OF SQUARE OF MAXIMAL OUTERPLANAR GRAPHS

    Institute of Scientific and Technical Information of China (English)

    Luo Xiaofang

    2007-01-01

    Let χ(G2) denote the chromatic number of the square of a maximal outerplanar graph G and Q denote a maximal outerplanar graph obtained by adding three chords and χ(G2) = Δ + 2 if and only if G is Q, where Δ represents the maximum degree of G.

  6. Chromatic induction effects in the Hermann grid illusion.

    Science.gov (United States)

    McCarter, A

    1979-01-01

    The chromatic Hermann grid illusion was investigated in sixteen subjects, with variation of the lightness contrast between the chromatic inducing squares and the background, and the saturation and hue of the inducing squares. Subjects made magnitude estimates of the sharpness and clarity of perceived dots at the intersections of the grid, and matched the appearances of the dots with Munsell chips. A chromatic induction effect was found to occur in the absence of lightness contrast, but the sharpness of the illusory dots increased with increasing lightness contrast (p less than 0.001). The saturation of the perceived dots increased with increases in the saturation of the inducing squares (p less than 0.05), and was higher for the longer wavelengths than for the shorter wavelengths (p less than 0.005). Neural units with center-surround arrangements responding differentially to light of the same color in the center and the surround, e.g. red off-centers and red on-surrounds, could account for the chromatic induction effect.

  7. Reduced Chromatic Discrimination in Children with Autism Spectrum Disorders

    Science.gov (United States)

    Franklin, Anna; Sowden, Paul; Notman, Leslie; Gonzalez-Dixon, Melissa; West, Dorotea; Alexander, Iona; Loveday, Stephen; White, Alex

    2010-01-01

    Atypical perception in Autism Spectrum Disorders (ASD) is well documented (Dakin & Frith, 2005). However, relatively little is known about colour perception in ASD. Less accurate performance on certain colour tasks has led some to argue that chromatic discrimination is reduced in ASD relative to typical development (Franklin, Sowden, Burley,…

  8. Chromatic number of graphs and edge Folkman numbers

    OpenAIRE

    Nenov, Nedyalko Dimov

    2010-01-01

    In the paper we give a lower bound for the number of vertices of a given graph using its chromatic number. We find the graphs for which this bound is exact. The results are applied in the theory of Foklman numbers.

  9. THE LIST CHROMATIC NUMBERS OF SOME PLANAR GRAPHS

    Institute of Scientific and Technical Information of China (English)

    LǖEnyue; ZhangKemin

    1999-01-01

    In this paper, the choosability of outerplanar graphs, 1-tree and strong 1-outerplanargraphs have been described completely. A precise upper bound of the list chromatic number of 1-outerplanar graphs is given, and that every 1-outerplanar graph with girth at least 4 is 3-choosable is proved.

  10. Electrochemical reduction of dilute chromate solutions on carbon felt electrodes

    NARCIS (Netherlands)

    Frenzel, Ines; Holdik, Hans; Barmashenko, Vladimir; Stamatialis, Dimitrios F.; Wessling, Matthias

    2006-01-01

    Carbon felt is a potential material for electrochemical reduction of chromates. Very dilute solutions may be efficiently treated due to its large specific surface area and high porosity. In this work, the up-scaling of this technology is investigated using a new type of separated cell and once-throu

  11. Removal of arsenate from water by using an Fe-Ce oxide adsorbent: Effects of coexistent fluoride and phosphate

    International Nuclear Information System (INIS)

    The Langmuir two-site equation, X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure spectroscopy have been employed to study the competitive behaviors of fluoride (F) and phosphate (P) in relation to arsenate adsorption on an Fe-Ce adsorbent as well as the mechanisms involved. The two-site isotherm revealed the presence of two kinds of adsorption sites with different binding affinities for arsenate. Both the total and low-binding-energy maximum adsorption capacities (Q and Q1) of arsenate decreased significantly even at a molar ratio of As/P = 1:0.1. The coexistence of F, only influenced the total Q of arsenate at high simultaneous F concentrations. The fact that Fe-Ce released 0.15-0.24 mmol sulfate for every mmol arsenate adsorbed suggested that, while sulfate groups might have played a role for adsorption, surface hydroxyl groups should be the major active sites. The XPS results indicated that arsenate and P are mainly adsorbed through the substitution of Fe surface active sites, while F is mainly adsorbed through substitution of Ce surface active sites. The As k-edge EXAFS data show that the second peak of Fe-Ce after arsenate adsorption is As-Fe shell, which further supported that arsenate adsorption occurs mainly at the Fe surface active sites.

  12. Draft Genome Sequence of Anaeromyxobacter sp. Strain PSR-1, an Arsenate-Respiring Bacterium Isolated from Arsenic-Contaminated Soil

    OpenAIRE

    Tonomura, Mimori; Ehara, Ayaka; Suzuki, Haruo; Amachi, Seigo

    2015-01-01

    Here, we report a draft genome sequence of Anaeromyxobacter sp. strain PSR-1, an arsenate-respiring bacterium isolated from arsenic-contaminated soil. It contained three distinct arsenic resistance gene clusters (ars operons), while no respiratory arsenate reductase gene (arr) was identified.

  13. Arsenate removal by layered double hydroxides embedded into spherical polymer beads: Batch and column studies.

    Science.gov (United States)

    Nhat Ha, Ho Nguyen; Kim Phuong, Nguyen Thi; Boi An, Tran; Mai Tho, Nguyen Thi; Ngoc Thang, Tran; Quang Minh, Bui; Van Du, Cao

    2016-01-01

    In this study, the performance of poly(layered double hydroxides) [poly(LDHs)] beads as an adsorbent for arsenate removal from aqueous solution was investigated. The poly(LDHs) beads were prepared by immobilizing LDHs into spherical alginate/polyvinyl alcohol (PVA)-glutaraldehyde beads (spherical polymer beads). Batch adsorption studies were conducted to assess the effect of contact time, solution pH, initial arsenate concentrations and co-existing anions on arsenate removal performance. The potential reuse of these poly(LDHs) beads was also investigated. Approximately 79.1 to 91.2% of arsenic was removed from an arsenate solution (50 mg As L(-1)) by poly(LDHs). The adsorption data were well described by the pseudo-second-order kinetics model and the Langmuir isotherm model, and the adsorption capacities of these poly(LDHs) beads at pH 8 were from 1.64 to 1.73 mg As g(-1), as calculated from the Langmuir adsorption isotherm. The adsorption ability of the poly(LDHs) beads decreased by approximately 5-6% after 5 adsorption-desorption cycles. Phosphates markedly decreased arsenate removal. The effect of co-existing anions on the adsorption capacity declined in the following order: HPO4 (2-) > HCO3 (-) > SO4 (2-) > Cl(-). A fixed-bed column study was conducted with real-life arsenic-containing water. The breakthrough time was found to be from 7 to 10 h. Under optimized conditions, the poly(LDHs) removed more than 82% of total arsenic. The results obtained in this study will be useful for further extending the adsorbents to the field scale or for designing pilot plants in future studies. From the viewpoint of environmental friendliness, the poly(LDHs) beads are a potential cost-effective adsorbent for arsenate removal in water treatment.

  14. Arsenate removal by layered double hydroxides embedded into spherical polymer beads: Batch and column studies.

    Science.gov (United States)

    Nhat Ha, Ho Nguyen; Kim Phuong, Nguyen Thi; Boi An, Tran; Mai Tho, Nguyen Thi; Ngoc Thang, Tran; Quang Minh, Bui; Van Du, Cao

    2016-01-01

    In this study, the performance of poly(layered double hydroxides) [poly(LDHs)] beads as an adsorbent for arsenate removal from aqueous solution was investigated. The poly(LDHs) beads were prepared by immobilizing LDHs into spherical alginate/polyvinyl alcohol (PVA)-glutaraldehyde beads (spherical polymer beads). Batch adsorption studies were conducted to assess the effect of contact time, solution pH, initial arsenate concentrations and co-existing anions on arsenate removal performance. The potential reuse of these poly(LDHs) beads was also investigated. Approximately 79.1 to 91.2% of arsenic was removed from an arsenate solution (50 mg As L(-1)) by poly(LDHs). The adsorption data were well described by the pseudo-second-order kinetics model and the Langmuir isotherm model, and the adsorption capacities of these poly(LDHs) beads at pH 8 were from 1.64 to 1.73 mg As g(-1), as calculated from the Langmuir adsorption isotherm. The adsorption ability of the poly(LDHs) beads decreased by approximately 5-6% after 5 adsorption-desorption cycles. Phosphates markedly decreased arsenate removal. The effect of co-existing anions on the adsorption capacity declined in the following order: HPO4 (2-) > HCO3 (-) > SO4 (2-) > Cl(-). A fixed-bed column study was conducted with real-life arsenic-containing water. The breakthrough time was found to be from 7 to 10 h. Under optimized conditions, the poly(LDHs) removed more than 82% of total arsenic. The results obtained in this study will be useful for further extending the adsorbents to the field scale or for designing pilot plants in future studies. From the viewpoint of environmental friendliness, the poly(LDHs) beads are a potential cost-effective adsorbent for arsenate removal in water treatment. PMID:26818806

  15. Simultaneous chromate reduction and azo dye decolourization by Brevibacterium casei: Azo dye as electron donor for chromate reduction

    International Nuclear Information System (INIS)

    Chromate [Cr(VI)] and azo dyes are common pollutants which may co-exist in some industrial effluents. Hence studies of biological treatment of industrial wastewater should include investigation of the co-removal of these two pollutants. Brevibacterium casei, which can reduce Cr(VI) in the presence of the azo dye Acid Orange 7 (AO7) under nutrient-limiting condition, was isolated from a sewage sludge sample of a dyeing factory. Response surface methodology, which is commonly used to optimize growth conditions for food microorganisms to maximize product(s) yield, was used to determine the optimal conditions for chromate reduction and dye decolourization by B. casei. The optimal conditions were 0.24 g/L glucose, 3.0 g/L (NH4)2SO4 and 0.2 g/L peptone at pH 7 and 35 deg. C. The predicted maximum chromate reduction efficiencies and dye decolourization were 83.4 ± 0.6 and 40.7 ± 1.7%, respectively. A new mechanism was proposed for chromate reduction coupling with AO7 decolourization by B. casei. Under nutrient-limiting condition, AO7 was used as an e- donor by the reduction enzyme(s) of B. casei for the reduction of Cr(VI). The resulted Cr(III) then complexed with the oxidized AO7 to form a purple coloured intermediate.

  16. Simultaneous chromate reduction and azo dye decolourization by Brevibacterium casei: Azo dye as electron donor for chromate reduction

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Tsz Wai; Cai Qinhong [Department of Biology, Chinese University of Hong Kong, Shatin, N.T. (Hong Kong); Wong, Chong-Kim [Department of Biology, Chinese University of Hong Kong, Shatin, N.T. (Hong Kong); Environmental Science Programme, Chinese University of Hong Kong, Shatin, N.T. (Hong Kong); Chow, Alex T. [Department of Biosystems Engineering, Clemson University, SC 29634 (United States); Department of Forestry and Natural Resources, Clemson University, SC 29634 (United States); Wong, Po-Keung, E-mail: pkwong@cuhk.edu.hk [Department of Biology, Chinese University of Hong Kong, Shatin, N.T. (Hong Kong); Environmental Science Programme, Chinese University of Hong Kong, Shatin, N.T. (Hong Kong)

    2010-10-15

    Chromate [Cr(VI)] and azo dyes are common pollutants which may co-exist in some industrial effluents. Hence studies of biological treatment of industrial wastewater should include investigation of the co-removal of these two pollutants. Brevibacterium casei, which can reduce Cr(VI) in the presence of the azo dye Acid Orange 7 (AO7) under nutrient-limiting condition, was isolated from a sewage sludge sample of a dyeing factory. Response surface methodology, which is commonly used to optimize growth conditions for food microorganisms to maximize product(s) yield, was used to determine the optimal conditions for chromate reduction and dye decolourization by B. casei. The optimal conditions were 0.24 g/L glucose, 3.0 g/L (NH{sub 4}){sub 2}SO{sub 4} and 0.2 g/L peptone at pH 7 and 35 deg. C. The predicted maximum chromate reduction efficiencies and dye decolourization were 83.4 {+-} 0.6 and 40.7 {+-} 1.7%, respectively. A new mechanism was proposed for chromate reduction coupling with AO7 decolourization by B. casei. Under nutrient-limiting condition, AO7 was used as an e{sup -} donor by the reduction enzyme(s) of B. casei for the reduction of Cr(VI). The resulted Cr(III) then complexed with the oxidized AO7 to form a purple coloured intermediate.

  17. Enhanced arsenate reduction by a CDC25-like tyrosine phosphatase explains increased phytochelatin accumulation in arsenate-tolerant Holcus lanatus.

    Science.gov (United States)

    Bleeker, Petra M; Hakvoort, Henk W J; Bliek, Mattijs; Souer, Erik; Schat, Henk

    2006-03-01

    Decreased arsenate [As(V)] uptake is the major mechanism of naturally selected As(V) hypertolerance in plants. However, As(V)-hypertolerant ecotypes also show enhanced rates of phytochelatin (PC) accumulation, suggesting that improved sequestration might additionally contribute to the hypertolerance phenotype. Here, we show that enhanced PC-based sequestration in As(V)-hypertolerant Holcus lanatus is not due to an enhanced capacity for PC synthesis as such, but to increased As(V) reductase activity. Vacuolar transport of arsenite-thiol complexes was equal in both ecotypes. Based on homology with the yeast As(V) reductase, Acr2p, we identified a Cdc25-like plant candidate, HlAsr, and confirmed the As(V) reductase activity of both HlAsr and the homologous protein from Arabidopsis thaliana. The gene appeared to be As(V)-inducible and its expression was enhanced in the As(V)-hypertolerant H. lanatus ecotype, compared with the non-tolerant ecotype. Homologous ectopic overexpression of the AtASR cDNA in A. thaliana produced a dual phenotype. It improved tolerance to mildly toxic levels of As(V) exposure, but caused hypersensitivity to more toxic levels. Arabidopsis asr T-DNA mutants showed increased As(V) sensitivity at low exposure levels and enhanced arsenic retention in the root. It is argued that, next to decreased uptake, enhanced expression of HlASR might act as an additional determinant of As(V) hypertolerance and As transport in H. lanatus.

  18. Phosphate and arsenate removal efficiency by thermostable ferritin enzyme from Pyrococcus furiosus using radioisotopes

    KAUST Repository

    Sevcenco, Ana-Maria

    2015-03-13

    Oxo-anion binding properties of the thermostable enzyme ferritin from Pyrococcus furiosus were characterized with radiography. Radioisotopes 32P and 76As present as oxoanions were used to measure the extent and the rate of their absorption by the ferritin. Thermostable ferritin proved to be an excellent system for rapid phosphate and arsenate removal from aqueous solutions down to residual concentrations at the picomolar level. These very low concentrations make thermostable ferritin a potential tool to considerably mitigate industrial biofouling by phosphate limitation or to remove arsenate from drinking water.

  19. Non-linear optical titanyl arsenates: Crystal growth and properties

    Science.gov (United States)

    Nordborg, Jenni Eva Louise

    Crystals are appreciated not only for their appearance, but also for their unique physical properties which are utilized by the photonic industry in appliances that we come across every day. An important part of enabling the technical use of optical devices is the manufacture of crystals. This dissertation deals with a specific group of materials called the potassium titanyl phosphate (KIP) family, known for their non-linear optical and ferroelectric properties. The isomorphs vary in their linear optical and dielectric properties, which can be tuned to optimize device performance by forming solid solutions of the different materials. Titanyl arsenates have a wide range of near-infrared transmission which makes them useful for tunable infrared lasers. The isomorphs examined in the present work were primarily RbTiOASO4 (RTA) and CsTiOAsO4 (CTA) together with the mixtures RbxCs 1-xTiOAsO4 (RCTA). Large-scale crystals were grown by top seeding solution growth utilizing a three-zone furnace with excellent temperature control. Sufficiently slow cooling and constant upward lifting produced crystals with large volumes useable for technical applications. Optical quality RTA crystals up to 10 x 12 x 20 mm were grown. The greater difficulty in obtaining good crystals of CTA led to the use of mixed RCTA materials. The mixing of rubidium and cesium in RCTA is more favorable to crystal growth than the single components in pure RTA and CTA. Mixed crystals are rubidium-enriched and contain only 20-30% of the cesium concentration in the flux. The cesium atoms show a preference for the larger cation site. The network structure is very little affected by the cation substitution; consequently, the non-linear optical properties of the Rb-rich isomorphic mixtures of RTA and CTA can be expected to remain intact. Crystallographic methods utilizing conventional X-ray tubes, synchrotron radiation and neutron diffraction have been employed to investigate the properties of the atomic

  20. Removal of Arsenic from Wastewaters by Airlift Electrocoagulation: Part 3: Copper Smelter Wastewater Treatment

    DEFF Research Database (Denmark)

    Hansen, H.K.; Ottosen, Lisbeth M.

    2010-01-01

    for arsenic and heavy metals with EC, mainly due to the very low pH. On the other hand, after a preliminary Ca(OH)2 treatment for sulphate and heavy metal removal, arsenic could be removed totally by EC. In addition, EC could also be applied as a final remediation control tool for arsenic since the national......-arsenate precipitates. This work evaluates the feasibility of EC as a treatment process at various stages during conventional copper smelter wastewater treatment - with a focus on arsenic. The reactor used is a batch airlift electrocoagulator. The results showed that raw copper smelter wastewater was difficult to treat...

  1. Chromatic Dispersion Monitoring Method Based on Phase Shift Technique

    Institute of Scientific and Technical Information of China (English)

    L(U) Chengang; WU Xing; ZENG Lizhu; QIN Yifan; ZU Peng; HU Zhixiong; GE Chunfeng

    2007-01-01

    The modulation phase shift method was used to measure chromatic dispersion in a standard single mode fiber for telecommunication. The modulation phase difference of the transmitted light at the wavelength of 1 532. 16 nm modulated by a radio frequency signal was measured, relative to the transmitted light at the wavelength of 1 549.33 nm modulated by the same signal. By introducing a reference light at the wavelength of 1 310 nm, a 1 310/1 550 nm wavelength division multiplexing was used instead of the high cost dense wavelength division multiplexing. In the experiment, two testing lights were coupled with the reference light to the fiber spools of different lengths, respectively. By finite difference method, the chromatic dispersion between the two testing lights was measured, and the fixed errors generated during transmission were less than 0.5 ps/(nm·km).

  2. Investigation of the chromate conversion coating on Alclad 2024 aluminium alloy: effect of the pH of the chromate bath

    NARCIS (Netherlands)

    Campestrini, P.; Westing, E.P.M. van; Hovestad, A.; Wit, J.H.W. de

    2002-01-01

    The parameters of the chromate bath, like temperature, pH, and fluoride content, strongly affect the morphology and chemical composition of the chromate conversion coating and as a consequence have a large influence on its corrosion performance. In this paper, electrochemical impedance spectroscopy

  3. Bioaccumulation and oxidative stress in Daphnia magna exposed to arsenite and arsenate.

    Science.gov (United States)

    Fan, Wenhong; Ren, Jinqian; Li, Xiaomin; Wei, Chaoyang; Xue, Feng; Zhang, Nan

    2015-11-01

    Arsenic pollution and its toxicity to aquatic organisms have attracted worldwide attention. The bioavailability and toxicity of arsenic are highly related to its speciation. The present study investigated the differences in bioaccumulation and oxidative stress responses in an aquatic organism, Daphnia magna, induced by 2 inorganic arsenic species (As(III) and As(V)). The bioaccumulation of arsenic, Na(+) /K(+) -adenosine triphosphatase (ATPase) activity, reactive oxygen species (ROS) content, total superoxide dismutase (SOD) activity, total antioxidative capability, and malondialdehyde content in D. magna were determined after exposure to 500 µg/L of arsenite and arsenate for 48 h. The results showed that the oxidative stress and antioxidative process in D. magna exposed to arsenite and arsenate could be divided into 3 phases, which were antioxidative response, oxidation inhibition, and antioxidative recovery. In addition, differences in bioaccumulation, Na(+) /K(+) -ATPase activity, and total SOD activity were also found in D. magna exposed to As(III) and As(V). These differences might have been the result of the high affinity of As(III) with sulfhydryl groups in enzymes and the structural similarity of As(V) to phosphate. Therefore, arsenate could be taken up by organisms through phosphate transporters, could substitute for phosphate in biochemical reactions, and could lead to a change in the bioaccumulation of arsenic and activity of enzymes. These characteristics were the possible reasons for the different toxicity mechanisms in the oxidative stress process of arsenite and arsenate. PMID:26084717

  4. Arsenate tolerance in Silene paradoxa does not rely on phytochelatin-dependent sequestration

    International Nuclear Information System (INIS)

    Arsenate tolerance, As accumulation and As-induced phytochelatin accumulation were compared in populations of Silene paradoxa, one from a mine site enriched in As, Cu and Zn, the other from an uncontaminated site. The mine population was significantly more arsenate-tolerant. Arsenate uptake and root-to-shoot transport were slightly but significantly higher in the non-mine plants. The difference in uptake was quantitatively insufficient to explain the difference in tolerance between the populations. As accumulation in the roots was similar in both populations, but the mine plants accumulated much less phytochelatins than the non-mine plants. The mean phytochelatin chain length, however, was higher in the mine population, possibly due to a constitutively lower cellular glutathione level. It is argued that the mine plants must possess an arsenic detoxification mechanism other than arsenate reduction and subsequent phytochelatin-based sequestration. This alternative mechanism might explain at least some part of the superior tolerance in the mine plants. - Neither decreased uptake nor phytochelatins seem to play a role in the As tolerance in Silene paradoxa

  5. Relief of arsenate toxicity by Cd-stimulated phytochelatin synthesis in the green alga Chlamydomonas reinhardtii.

    Science.gov (United States)

    Kobayashi, Isao; Fujiwara, Shoko; Saegusa, Hirotaka; Inouhe, Masahiro; Matsumoto, Hiroko; Tsuzuki, Mikio

    2006-01-01

    In most photosynthetic organisms, inorganic arsenic taken up into the cells inhibits photosynthesis and cellular growth. In a green alga, Chlamydomonas reinhardtii, 0.5 mM arsenate inhibited photosynthesis almost completely within 30 min. However, in cells acclimated with a sublethal concentration (0.05 to 0.1 mM) of Cd, the inhibition of photosynthesis at 30 min after the addition of arsenate was relieved by more than 50%. The concentrations of arsenic incorporated into the cells were not significantly different between the Cd-acclimated and the non-acclimated cells. The Cd-acclimated cells accumulated Cd and synthesized phytochelatin (PC) peptides, which are known to play an important role in detoxification of heavy metals in plants. By the addition of an inhibitor of glutathione (an intermediate in the PC biosynthetic pathway) biosynthesis, buthionine sulfoximine, cells lost not only Cd tolerance but also arsenate tolerance. These results suggest that glutathione and/or PCs synthesized in Cd-acclimated cells are involved in mechanisms of arsenate tolerance.

  6. XAFS study of starch-stabilized magnetite nanoparticles and surface speciation of arsenate

    International Nuclear Information System (INIS)

    It has been shown that starch can effectively stabilize nanoscale magnetite particles, and starch-stabilized magnetite nanoparticles (SMNP) are promising for in situ remediation of arsenic-contaminated soils. However, a molecular level understanding has been lacking. Here, we carried out XAFS studies to bridge this knowledge gap. Fe K-edge XAFS spectra indicated that the Fe-O and Fe-Fe coordination numbers of SMNP were lower than those for bare magnetite particles, and these coordination numbers decreased with increasing starch concentration. The decrease in the average coordination number at elevated stabilizer concentration was attributed to the increase in the surface-to-volume ratio. Arsenic K-edge XAFS spectra indicated that adsorbed arsenate on SMNP consisted primarily of binuclear bidentate (BB) complexes and monodentate mononuclear (MM) complexes. More BB complexes (energetically more favorable) were observed at higher starch concentrations, indicating that SMNP not only offered greater adsorption surface area, but also stronger adsorption affinity toward arsenate. - Graphical abstract: Display Omitted Highlights: → Starch as a stabilizer of magnetite nanoparticles. → Characterization of starch-stabilized magnetite nanoparticles by XAFS. → Fe-O and Fe-Fe coordination numbers decreased with starch concentration increasing. → Ratio of two arsenate complexes adsorbed varied with starch concentration. → More binuclear bidentate arsenic complexes formed at higher starch concentrations. - The presence of starch leads to the formation of more effective adsorbing sites and stronger adsorption affinity of arsenate on magnetite nanoparticle surfaces.

  7. Arsenate tolerance in Silene paradoxa does not rely on phytochelatin-dependent sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Arnetoli, Miluscia [Section of Plant Ecology and Physiology, Department of Plant Biology, University of Florence, via Micheli 1, 50121 Firenze (Italy)], E-mail: miluscia@gmail.com; Vooijs, Riet; Bookum, Wilma ten [Institute of Molecular and Cellular Biology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands); Galardi, Francesca; Gonnelli, Cristina; Gabbrielli, Roberto [Section of Plant Ecology and Physiology, Department of Plant Biology, University of Florence, via Micheli 1, 50121 Firenze (Italy); Schat, Henk; Verkleij, Jos A.C. [Institute of Molecular and Cellular Biology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands)

    2008-04-15

    Arsenate tolerance, As accumulation and As-induced phytochelatin accumulation were compared in populations of Silene paradoxa, one from a mine site enriched in As, Cu and Zn, the other from an uncontaminated site. The mine population was significantly more arsenate-tolerant. Arsenate uptake and root-to-shoot transport were slightly but significantly higher in the non-mine plants. The difference in uptake was quantitatively insufficient to explain the difference in tolerance between the populations. As accumulation in the roots was similar in both populations, but the mine plants accumulated much less phytochelatins than the non-mine plants. The mean phytochelatin chain length, however, was higher in the mine population, possibly due to a constitutively lower cellular glutathione level. It is argued that the mine plants must possess an arsenic detoxification mechanism other than arsenate reduction and subsequent phytochelatin-based sequestration. This alternative mechanism might explain at least some part of the superior tolerance in the mine plants. - Neither decreased uptake nor phytochelatins seem to play a role in the As tolerance in Silene paradoxa.

  8. SORPTION OF ARSENATE AND ARSENITE ON A RUTHENIUM COMPOUND: A MACROSCOPIC AND MICROSCOPIC STUDY

    Science.gov (United States)

    Sorption of arsenate and arsenite was examined on a ruthenium compound using macroscopic and microscopic techniques. Batch sorption experiments at pH 4,5,6, 7 and 8 were employed to construct constant solid solution ratio isotherms (CSI). After equilibration at the appropriate pH...

  9. Detection of Perturbation in Chromatic and Luminance-Defined Lines and Square-Waves

    Directory of Open Access Journals (Sweden)

    R.J Sharman

    2014-08-01

    Full Text Available The composition of a stimulus may affect how cues are combined. A thin luminance ring surrounding a uniform chromatic test facilitates contrast detection as much as a uniform luminance pedestal (Cole, Stromeyer & Kronauer, 1990, JOSA A, 7(1, 128-140. This could suggest that there is a specific facilitatory relationship between luminance lines and chromatic edges that is not present in other combinations. Therefore, combining luminance lines and chromatic edges could also improve performance in edge detection tasks. Here we use a novel task, perturbation detection, target gratings were sinusoidally perturbed in space and subjects were asked to detect which of two stimuli was not straight. Perturbation thresholds, were measured for chromatic and luminance defined line and square-wave gratings alone and in combination. The introduction of a line mask produced increased thresholds in all conditions. However, the introduction of a chromatic square-wave mask improved perception of perturbation in luminance lines, whereas the introduction of a luminance defined square-wave mask has little effect on the perturbation thresholds for chromatic lines. This could suggest that when a luminance line is presented with a chromatic edge, such as the chromatic boundaries in a square-wave grating, the chromatic information becomes ‘tied’ to the luminance information. The perceived location of the chromatic edge may be determined by the location of the luminance line.

  10. The total chromatic number of regular graphs of high degree

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The total chromatic number χT (G) of a graph G is the minimum number of colors needed to color the edges and the vertices of G so that incident or adjacent elements have distinct colors. We show that if G is a regular graph and d(G) 32 |V (G)| + 263 , where d(G) denotes the degree of a vertex in G, then χT (G) d(G) + 2.

  11. The total chromatic number of regular graphs of high degree

    Institute of Scientific and Technical Information of China (English)

    XIE DeZheng; YANG WanNian

    2009-01-01

    The total chromatic number XT (G) of a graph G is the minimum number of colors needed to color the edges and the vertices of G so that incident or adjacent elements have distinct colors.We show that if G is a regular graph and d(G)≥2/3|V(G)|+23/6,where d(G) denotes the degree of a vertex in G,then xT(G)≤d(G) + 2.

  12. The dependence of luminous efficiency on chromatic adaptation

    OpenAIRE

    Stockman, A.; Jaegle, H.; Pirzer, M.; Sharpe, L. T.

    2008-01-01

    We investigated the dependence of luminous efficiency on background chromaticity by measuring 25-Hz heterochromatic flicker photometry (HFP) matches in six genotyped male observers on 21 different 1000-photopic-troland adapting fields: 14 spectral ones ranging from 430 to 670 nm and 7 bichromatic mixtures of 478 and 577 nm that varied in luminance ratio. Each function was analyzed in terms of the best-fitting linear combination of the long- (L) and middle- (M) wavelength sensitive cone fundam...

  13. Chromate abatement in the Y-12 Plant's New Hope Pond

    International Nuclear Information System (INIS)

    Results are reported from a 15-months field study that utilized four nonchromate-based water-treatment programs in 16 low-temperature (less than 1000F) cooling towers using corrosion and deposition studies, microbiological control, and plant effluent creek analyses as evaluation parameters. The study succeeded in bringing the chromate content of effluent of the New Hope Pond at the Oak Ridge Y-12 Plant to the limits established by the Environmental Protection Agency. (auth)

  14. Tailoring chromatic dispersion in chalcogenide-tellurite microstructured optical fiber

    Science.gov (United States)

    Kohoutek, Tomas; Duan, Zhongchao; Kawashima, Hiroyasu; Cheng, Tonglei; Suzuki, Takenobu; Matsumoto, Morio; Misumi, Takashi; Ohishi, Yasutake

    2014-08-01

    We report fabrication of a highly nonlinear hybrid microstructured optical fiber composed of chalcogenide glass core and tellurite glass cladding. The flattened chromatic dispersion can be achieved in such an optical fiber with near zero dispersion wavelength at telecommunication wavelengths λ = 1.35-1.7 μm, which cannot be achieved in chalcogenide glass optical fibers due to their high refractive index, i.e. n > 2.1. We demonstrate a hybrid 4-air hole chalcogenide-tellurite optical fiber (Δn = 0.25) with flattened chromatic dispersion around λ = 1.55 μm. In optimized 12-air hole optical fiber composed of the same glasses, the chromatic dispersion values were achieved between -20 and 32 ps/nm/km in a broad wavelength range of 1.5-3.8 μm providing the fiber with extremely high nonlinear coefficient 86,000 km-1W-1. Hybrid chalcogenide/tellurite fibers pumped with the near infrared lasers give good promise for broadband optical amplification, wavelength conversion, and supercontinuum generation in the near- to mid-infrared region.

  15. "Tilt" in color space: Hue changes induced by chromatic surrounds.

    Science.gov (United States)

    Klauke, Susanne; Wachtler, Thomas

    2015-01-01

    The perceived color of a chromatic stimulus is influenced by the chromaticity of its surround. To investigate these influences along the dimension of hue, we measured hue changes induced in stimuli of different hues by isoluminant chromatic surrounds. Generally, induced hue changes were directed in color space away from the hue of the inducing surround and depended on the magnitude on the hue difference between stimulus and surround. With increasing difference in hue between stimulus and surround, induced hue changes increased up to a maximum and then decreased for larger differences. This qualitative pattern was similar for different inducers, but quantitatively, induction was weaker along some directions in cone-opponent color space than along other directions. The strongest induction effects were found along an oblique, blue-yellow axis that corresponds to the daylight axis. The overall pattern of the induction effect shows similarities to the well-known tilt effect, where shifts in perceived angle of oriented stimuli are induced by oriented surrounds. This suggests analogous neural representations and similar mechanisms of contextual processing for different visual features such as orientation and color.

  16. Chemical Effects following Thermal Neutron Capture in Potassium Chromate

    International Nuclear Information System (INIS)

    The chemical effects accompanying radiative thermal neutron capture in potassium chromate have been extensively studied in the past few years. The presence of radioactive chromic ions formed upon dissolving neutron irradiated potassium chromate and the reactions from heating the material above 150°C have been explained by reactions involving the presence of CrO4+ ions in the crystal lattice. A new analytical method, based on the slow rate of exchange between chromo and chromic ions, has been used to show that more than 90% of the reduced chromium ions are present in the +2 valence state. The results obtained, using the new analytical method, indicate that the processes taking place during dissolution are hydration processes while the reduction of chromium fragments takes place in the crystal. Isothermal and isochronical annealing experiments carried out on crystals irradiated at room temperature show that three annealing reactions occur between 60° and 275°C. The influence of quenching and foreign ions on the three annealing reactions has been studied. Investigations made in parallel with chemical changes of Cr51 recoil species and electronic changes in irradiated potassium chromate during post-irradiation treatment have been carried out measuring the thermoluminescence spectrum, the electrical conductivity and the chemical distribution of Cr51 fragments. The results show that the chemical annealing reactions are associated with electronic changes indicating a close relation between chemical annealing and the disappearance of charge carriers. (author)

  17. Evaluating the performance of modified adsorbent of zero valent iron nanoparticles – Chitosan composite for arsenate removal from aqueous solutions

    Directory of Open Access Journals (Sweden)

    K Yaghmaeian

    2016-03-01

    Full Text Available Background and Objective: Arsenic is one of the most toxic pollutants in groundwater and surface water. Arsenic could have lots of adverse impacts on human health. Therefore, access to new technologies is required to achieve the arsenic standard. Materials and Methods: The present study was conducted at laboratory scale in non-continuous batches. The adsorbent of zero-valent iron nanoparticles -Chitosan was produced through reducing ferric iron by sodium borohydride (NaBH4 in the presence of chitosan as a stabilizer. At first, the effect of various parameters such as contact time (5-120 min, pH (3-10, adsorbent dose (0.3-3.5 g/L and initial concentration of arsenate (2-10 mg/L were investigated on process efficiency. Then optimum conditions in terms of contact time, pH, adsorbent dose and initial concentration of arsenate were determined by RSM method. Freundlich and Langmuir isotherm model equilibrium constant, pseudo-first and second order kinetic constants were calculated. The residual arsenate was measured y using ICP-AES. Results: The optimum values based on RSM for pH, absorbent dose, contact time, and initial concentration of arsenate were 7.16, 3.04 g/L, 91.48 min, and 9.71 mg/L respectively. Langmuir isotherm with R2= 0.9904 for Arsenate was the best graph for the experimental data. According to Langmuir isotherm model, the maximum amount of arsenate adsorption was 135.14mg/g. . The investigation of arsenate adsorption kinetics showed that arsenate adsorption follows the pseudo-second kinetics model. Conclusion: This research showed that the adsorption process is depended on pH. With increasing pH, the ability of amine groups in chitosan are decreased to protonation, caused to decrease the efficiency of arsenate removal at high pH.

  18. Competitive adsorption of arsenate and phosphate onto calcite; experimental results and modeling with CCM and CD-MUSIC

    Science.gov (United States)

    Sø, Helle Ugilt; Postma, Dieke; Jakobsen, Rasmus; Larsen, Flemming

    2012-09-01

    The competitive adsorption of arsenate and phosphate onto calcite was studied in batch experiments using calcite-equilibrated solutions. The solutions had circum-neutral pH (7-8.3) and covered a wide span in the activity of Ca2+ and CO32-. The results show that the adsorption of arsenate onto calcite is strongly reduced by the presence of phosphate, whereas phosphate adsorption is only slightly reduced by arsenate addition. Simultaneous and sequential addition (3 h apart) yields the same reduction in adsorption, underlining the high reversibility of the system. The reduction in adsorption of both arsenate and phosphate is most likely due to competition for the same sorption sites at the calcite surface, considering the similarity in sorption edges, pKa's and geometry of the two anions. The strong reduction in arsenate adsorption by competition with phosphate suggests that adsorption of arsenate onto calcite is of minor importance in most groundwater aquifers, as phosphate is often present at concentration levels sufficient to significantly reduce arsenate adsorption. The CD-MUSIC model for calcite was used successfully to model adsorption of arsenate and phosphate separately. By combining the models for single sorbate systems the competitive adsorption of phosphate and arsenate onto calcite in the binary system could be predicted. This is in contrast to the constant capacitance model (CCM) which under-predicted the competition when combining the models for single sorbate systems. This study clearly shows the importance of performing competitive adsorption studies for validation of multi-component models and for estimating the mobility of an ion in the environment.

  19. Effects of sodium arsenate exposure on liver fatty acid profiles and oxidative stress in rats.

    Science.gov (United States)

    Kharroubi, Wafa; Dhibi, Madiha; Haouas, Zohra; Chreif, Imed; Neffati, Fadoua; Hammami, Mohamed; Sakly, Rachid

    2014-02-01

    The present study aimed to evaluate the effect of arsenic on liver fatty acids (FA) composition, hepatotoxicity and oxidative status markers in rats. Male rats were randomly devised to six groups (n=10 per group) and exposed to sodium arsenate at a dose of 1 and 10 mg/l for 45 and 90 days. Arsenate exposure is associated with significant changes in the FA composition in liver. A significant increase of saturated fatty acids (SFA) in all treated groups (p<0.01) and trans unsaturated fatty acids (trans UFA) in rats exposed both for short term for 10 mg/l (p<0.05) and long term for 1 and 10 mg/l (p<0.001) was observed. However, the cis UFA were significantly decreased in these groups (p<0.05). A markedly increase of indicator in cell membrane viscosity expressed as SFA/UFA was reported in the treated groups (p<0.001). A significant increase in the level of malondialdehyde by 38.3 % after 90 days of exposure at 10 mg/l was observed. Compared to control rats, significant liver damage was observed at 10 mg/l of arsenate by increasing plasma marker enzymes after 90 days. It is through the histological investigations in hepatic tissues of exposed rats that these damage effects of arsenate were confirmed. The antioxidant perturbations were observed to be more important at groups treated by the high dose (p<0.05). An increase in the level of protein carbonyls was observed in all treated groups (p<0.05). The present study provides evidence for a direct effect of arsenite on FA composition disturbance causing an increase of SFA and TFAs isomers, liver dysfunction and oxidative stress. Therefore, arsenate can lead to hepatic damage and propensity towards liver cancer. PMID:23949113

  20. Behavior of Eucalyptus urophylla and Eucalyptus citriodora Seedlings Grown in Soil Contaminated by Arsenate

    Directory of Open Access Journals (Sweden)

    Roseli Freire Melo

    2016-01-01

    Full Text Available ABSTRACT Persistent areas of tailings and deposits from coal and gold mining may present high levels of arsenic (As, mainly in the arsenate form, endangering the environment and human health. The establishment of vegetation cover is a key step to reclaiming these environments. Thus, this study aimed to evaluate the potential of Eucalyptus urophylla and E. citriodora seedlings for use in phytoremediation programs of arsenate-contaminated areas. Soil samples were incubated at increasing rates (0, 50, 100, 200 and 400 mg dm-3 of arsenic (arsenate form, using Na2HAsO4 for 15 days. The seedlings were produced in a substrate (vermiculite + sawdust and were transplanted to the pots with soil three months after seed germination. The values of plant height and diameter were taken during transplanting and 30, 60 and 90 days after transplanting. In the last evaluation, the total leaf area and biomass of shoots and roots were also determined. The values of available As in soil which caused a 50 % dry matter reduction (TS50%, the As translocation index (TI from the roots to the shoot of the plants, and its bioconcentration factor (BF were also calculated. Higher levels of arsenate in the soil significantly reduced the dry matter production of roots and shoots and the height of both species, most notably in E. urophylla plants. The highest levels of As were found in the root, with higher values for E. citriodora (ranging from 253.86 to 400 mg dm-3. The TI and BF were also reduced with As doses, but the values found in E. citriodora were significantly higher than in E. urophylla. E. citriodora plants presented a higher capacity to tolerate As and translocate it to the shoot than E. urophylla. Although these species cannot be considered as hyperaccumulators of As, E. citriodora presented the potential to be used in phytoremediation programs in arsenate-contaminated areas due to the long-term growth period of this species.

  1. Chromate Reduction in Serratia marcescens Isolated from Tannery Effluent and Potential Application for Bioremediation of Chromate Pollution

    Directory of Open Access Journals (Sweden)

    M.A. Mondaca

    2002-01-01

    Full Text Available Pollution of aquatic systems by heavy metals has resulted in increasing environmental concern because they cannot be biodegraded. One metal that gives reason for concern due to its toxicity is chromium. Cr(VI and Cr(III are the principal forms of chromium found in natural waters. A chromate-resistant strain of the bacterium S. marcescens was isolated from tannery effluent. The strain was able to reduce Cr(VI to Cr(III, and about 80% of chromate was removed from the medium. The reduction seems to occur on the cell surface. Transmission electron microscopic examination of cells revealed that particles were deposited on the outside of bacterial cells. A stable biofilm was formed in less than 10 h, reaching around 1010 cfu attached per milligram of activated carbon. These findings demonstrate that immobilized S. marcescens might be used in industrial waste treatment processes.

  2. Chromatic Sums of Biloopless Nonseparable Near-Triangulations on the Projective Plane

    Institute of Scientific and Technical Information of China (English)

    Zhao-xiang Li; Yan-pei Liu; Bing-feng Si

    2013-01-01

    In this paper,the chromatic sum functions of rooted biloopless nonseparable near-triangulations on the sphere and the projective plane are studied.The chromatic sum function equations of such maps are obtained.From the chromatic sum equations of such maps,the enumerating function equations of such maps are derived.An asymptotic evaluation and some explicit expression of enumerating functions are also derived.

  3. Preventing potential mixed waste generation by replacing CCW potassium chromate corrosion inhibitor

    International Nuclear Information System (INIS)

    Wisconsin Public Service Corporation personnel at the Kewaunee Nuclear Power Plant decided to replace their potassium chromate inhibitor in the component cooling water (CCW) system in order to eliminate the possibility of needing to dispose of radioactively contaminated chromate solution in the future. This paper discusses the replacement effort, which included identifying an environmentally acceptable replacement inhibitor that was as effective as chromate for corrosion inhibition and implementing the inhibitor changeover program

  4. EVALUATION OF CORRECTION METHODS OF CHROMATIC ABERRATION IN DIGITAL CAMERA IMAGES

    OpenAIRE

    Matsuoka, R; Asonuma, K.; Takahashi, G; Danjo, T.; Hirana, K.

    2012-01-01

    This paper reports an experiment conducted to evaluate correction methods of chromatic aberrations in images acquired by a nonmetric digital camera. The chromatic aberration correction methods evaluated in the experiment are classified into two kinds. One is the method to correct image coordinates by using camera calibration results of color-separated images. The other is the method based on the assumption that the magnitude of chromatic aberrations can be expressed by a function of ...

  5. Removal of chromate in a permeable reactive barrier using zero-valent iron

    DEFF Research Database (Denmark)

    Kjeldsen, Peter; Locht, T

    2002-01-01

    Chromate is a commonly found groundwater contaminant. Permeable reactive barriers containing zero-valent iron as iron filings are able to remove the chromate by a combined reduction/precipitation reaction. However, due to the passivation of the reduction capability of the iron surfaces by the pre......Chromate is a commonly found groundwater contaminant. Permeable reactive barriers containing zero-valent iron as iron filings are able to remove the chromate by a combined reduction/precipitation reaction. However, due to the passivation of the reduction capability of the iron surfaces...

  6. Electrochemical Behavior of 2205 Duplex Stainless Steel in NaCl Solution with Different Chromate Contents

    Science.gov (United States)

    Luo, H.; Dong, C. F.; Cheng, X. Q.; Xiao, K.; Li, X. G.

    2012-07-01

    The electrochemical behavior of 2205 duplex stainless steel in NaCl solution with different chromate contents were investigated by potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis, and scanning electron microscope (SEM). The effect of chromate on passivity and pitting behavior of stainless steel was also studied. The results showed that pitting susceptibility as well as semiconducting properties of passive film is heavily dependent on the chromate concentration. There exists a critical chromate value (about 0.03 M in 1 M NaCl solutions) below which the pitting corrosion on the stainless steel would be inhibited and above which it would be accelerated.

  7. Definition and measurement of the beam propagation factor M2 for chromatic laser beams

    Institute of Scientific and Technical Information of China (English)

    Tao Fang; Xin Ye; Jinfu Niu; Jianqiu Xu

    2006-01-01

    The concept of the beam propagation factor M2 is extended for chromatic laser beams. The definition of the beam propagation factor can be generalized with the weighted effective wavelength. Using the new definition of factor M2, the propagation of chromatic beams can be analyzed by the beam propagation factor M2 as same as that of monochromatic beams. A simple method to measure the chromatic beam factor M2 is demonstrated. The chromatic factor M2 is found invariable while the laser beam propagates through the dispersion-free ABCD system.

  8. Chromatic Sums of Nonseparable Near-Triangulations on the Projective Plane

    Institute of Scientific and Technical Information of China (English)

    Zhao Xiang LI; Wei HE

    2012-01-01

    In this paper,we study the chromatic sum functions of rooted nonseparable neartriangulations on the sphere and the projective plane.The chromatic sum function equations of such maps are obtained.From the chromatic sum equations of such maps,the enumerating function equations of such maps are derived.Applying chromatic sum theory,the enumerating problem of different sorts maps can be studied,and a new method of enumeration can be obtained.Moreover,an asymptotic evaluation and some explicit expression of enumerating functions are also derived.

  9. Genome-wide association mapping identifies a new arsenate reductase enzyme critical for limiting arsenic accumulation in plants.

    Directory of Open Access Journals (Sweden)

    Dai-Yin Chao

    2014-12-01

    Full Text Available Inorganic arsenic is a carcinogen, and its ingestion through foods such as rice presents a significant risk to human health. Plants chemically reduce arsenate to arsenite. Using genome-wide association (GWA mapping of loci controlling natural variation in arsenic accumulation in Arabidopsis thaliana allowed us to identify the arsenate reductase required for this reduction, which we named High Arsenic Content 1 (HAC1. Complementation verified the identity of HAC1, and expression in Escherichia coli lacking a functional arsenate reductase confirmed the arsenate reductase activity of HAC1. The HAC1 protein accumulates in the epidermis, the outer cell layer of the root, and also in the pericycle cells surrounding the central vascular tissue. Plants lacking HAC1 lose their ability to efflux arsenite from roots, leading to both increased transport of arsenic into the central vascular tissue and on into the shoot. HAC1 therefore functions to reduce arsenate to arsenite in the outer cell layer of the root, facilitating efflux of arsenic as arsenite back into the soil to limit both its accumulation in the root and transport to the shoot. Arsenate reduction by HAC1 in the pericycle may play a role in limiting arsenic loading into the xylem. Loss of HAC1-encoded arsenic reduction leads to a significant increase in arsenic accumulation in shoots, causing an increased sensitivity to arsenate toxicity. We also confirmed the previous observation that the ACR2 arsenate reductase in A. thaliana plays no detectable role in arsenic metabolism. Furthermore, ACR2 does not interact epistatically with HAC1, since arsenic metabolism in the acr2 hac1 double mutant is disrupted in an identical manner to that described for the hac1 single mutant. Our identification of HAC1 and its associated natural variation provides an important new resource for the development of low arsenic-containing food such as rice.

  10. Paper-based chromatic toxicity bioassay by analysis of bacterial ferricyanide reduction.

    Science.gov (United States)

    Pujol-Vila, F; Vigués, N; Guerrero-Navarro, A; Jiménez, S; Gómez, D; Fernández, M; Bori, J; Vallès, B; Riva, M C; Muñoz-Berbel, X; Mas, J

    2016-03-01

    Water quality assessment requires a continuous and strict analysis of samples to guarantee compliance with established standards. Nowadays, the increasing number of pollutants and their synergistic effects lead to the development general toxicity bioassays capable to analyse water pollution as a whole. Current general toxicity methods, e.g. Microtox(®), rely on long operation protocols, the use of complex and expensive instrumentation and sample pre-treatment, which should be transported to the laboratory for analysis. These requirements delay sample analysis and hence, the response to avoid an environmental catastrophe. In an attempt to solve it, a fast (15 min) and low-cost toxicity bioassay based on the chromatic changes associated to bacterial ferricyanide reduction is here presented. E. coli cells (used as model bacteria) were stably trapped on low-cost paper matrices (cellulose-based paper discs, PDs) and remained viable for long times (1 month at -20 °C). Apart from bacterial carrier, paper matrices also acted as a fluidic element, allowing fluid management without the need of external pumps. Bioassay evaluation was performed using copper as model toxic agent. Chromatic changes associated to bacterial ferricyanide reduction were determined by three different transduction methods, i.e. (i) optical reflectometry (as reference method), (ii) image analysis and (iii) visual inspection. In all cases, bioassay results (in terms of half maximal effective concentrations, EC50) were in agreement with already reported data, confirming the good performance of the bioassay. The validation of the bioassay was performed by analysis of real samples from natural sources, which were analysed and compared with a reference method (i.e. Microtox). Obtained results showed agreement for about 70% of toxic samples and 80% of non-toxic samples, which may validate the use of this simple and quick protocol in the determination of general toxicity. The minimum instrumentation

  11. Arsenate impact on the metabolite profile, production and arsenic loading of xylem sap in cucumbers (Cucumis sativus L.

    Directory of Open Access Journals (Sweden)

    Kalle eUroic

    2012-04-01

    Full Text Available Arsenic uptake and translocation studies on xylem sap focus generally on the concentration and speciation of arsenic in the xylem. Arsenic impact on the xylem sap metabolite profile and its production during short term exposure has not been reported in detail. To investigate this, cucumbers were grown hydroponically and arsenate (AsV and DMA were used for plant treatment for 24 h. Total arsenic and arsenic speciation in xylem sap was analysed including a metabolite profiling under arsenate stress. Produced xylem sap was quantified and absolute arsenic transported was determined. AsV exposure has a significant impact on the metabolite profile of xylem sap. Four m/z values corresponding to four compounds were up regulated, one compound down regulated by arsenate exposure. The compound down regulated was identified to be isoleucine. Furthermore, arsenate has a significant influence on sap production, leading to a reduction of up to 96 % sap production when plants are exposed to 1000 μg kg-1 arsenate. No difference to control plants was observed when plants were exposed to 1000 μg kg-1 DMA. Absolute arsenic amount in xylem sap was the lowest at high arsenate exposure. These results show that AsV has a significant impact on the production and metabolite profile of xylem sap. The physiological importance of isoleucine needs further attention.

  12. On the Independence Number of Edge Chromatic Critical Graphs

    Directory of Open Access Journals (Sweden)

    Pang Shiyou

    2014-08-01

    Full Text Available In 1968, Vizing conjectured that for any edge chromatic critical graph G = (V,E with maximum degree △ and independence number α (G, α (G ≤. It is known that α (G < |V |. In this paper we improve this bound when △≥ 4. Our precise result depends on the number n2 of 2-vertices in G, but in particular we prove that α (G ≤|V | when △ ≥ 5 and n2 ≤ 2(△− 1

  13. Automated selection of LEDs by luminance and chromaticity coordinate

    CERN Document Server

    Fischer, Ulrich H P; Reinboth, Christian

    2010-01-01

    The increased use of LEDs for lighting purposes has led to the development of numerous applications requiring a pre-selection of LEDs by their luminance and / or their chromaticity coordinate. This paper demonstrates how a manual pre-selection process can be realized using a relatively simple configuration. Since a manual selection service can only be commercially viable as long as only small quantities of LEDs need to be sorted, an automated solution suggests itself. This paper introduces such a solution, which has been developed by Harzoptics in close cooperation with Rundfunk Gernrode. The paper also discusses current challenges in measurement technology as well as market trends.

  14. Chromatic Dispersion Compensation Using Photonic Crystal Fibers with Hexagonal Distribution

    Directory of Open Access Journals (Sweden)

    Erick E. Reyes-Vera

    2013-11-01

    Full Text Available In this paper we show various configurations of photonic crystal fiber with hexagonal holes distribution for compensation of chromatic dispersion in optical communications links. The vectorial finite element method with scattering boundary condition was used for the analysis of the fibers. From these results it was estimated variation of the dispersion and the dispersion slope with respect to change in the diameter of the holes in the microstructure. With the above was possible to obtain values of dispersion in the C and L bands of telecommunications close to -850 ps / nm * km, with confinement losses 10-3 dB / km

  15. Chromatic Shadow Detection and Tracking for Moving Foreground Segmentation

    DEFF Research Database (Denmark)

    Huerta, Ivan; Holte, Michael Boelstoft; Moeslund, Thomas B.;

    2015-01-01

    Advanced segmentation techniques in the surveillance domain deal with shadows to avoid distortions when detecting moving objects. Most approaches for shadow detection are still typically restricted to penumbra shadows and cannot cope well with umbra shadows. Consequently, umbra shadow regions...... chrominance angle and brightness distortions are analysed for each potential shadow region for detecting the umbra shadow regions. Our second contribution refines even further the segmentation results: a tracking-based top-down approach increases the performance of our bottom-up chromatic shadow detection...... for multiple well-known surveillance image databases which contain different shadowed materials and illumination conditions....

  16. Arsenite-oxidizing and arsenate-reducing bacteria associated with arsenic-rich groundwater in Taiwan

    Science.gov (United States)

    Liao, Vivian Hsiu-Chuan; Chu, Yu-Ju; Su, Yu-Chen; Hsiao, Sung-Yun; Wei, Chia-Cheng; Liu, Chen-Wuing; Liao, Chung-Min; Shen, Wei-Chiang; Chang, Fi-John

    2011-04-01

    Drinking highly arsenic-contaminated groundwater is a likely cause of blackfoot disease in Taiwan, but microorganisms that potentially control arsenic mobility in the subsurface remain unstudied. The objective of this study was to investigate the relevant arsenite-oxidizing and arsenate-reducing microbial community that exists in highly arsenic-contaminated groundwater in Taiwan. We cultured and identified arsenic-transforming bacteria, analyzed arsenic resistance and transformation, and determined the presence of genetic markers for arsenic transformation. In total, 11 arsenic-transforming bacterial strains with different colony morphologies and varying arsenic transformation abilities were isolated, including 10 facultative anaerobic arsenate-reducing bacteria and one strictly aerobic arsenite-oxidizing bacterium. All of the isolates exhibited high levels of arsenic resistance with minimum inhibitory concentrations of arsenic ranging from 2 to 200 mM. Strain AR-11 was able to rapidly oxidize arsenite to arsenate at concentrations relevant to environmental groundwater samples without the addition of any electron donors or acceptors. We provide evidence that arsenic-reduction activity may be conferred by the ars operon(s) that were not amplified by the designed primers currently in use. The 16S rRNA sequence analysis grouped the isolates into the following genera: Pseudomonas, Bacillus, Psychrobacter, Vibrio, Citrobacter, Enterobacter, and Bosea. Among these genera, we present the first report of the genus Psychrobacter being involved in arsenic reduction. Our results further support the hypothesis that bacteria capable of either oxidizing arsenite or reducing arsenate coexist and are ubiquitous in arsenic-contaminated groundwater.

  17. Effects of Chromate and Non-Chromate Coating Systems on Environmentally Assisted Fatigue of an Aluminum Alloy

    Science.gov (United States)

    Schubbe, Joel J.; Westmoreland, Sophoria N.

    2014-10-01

    Fatigue crack growth testing of 2024-T3 Aluminum plate was performed using compact tension (CT) specimens with chromate and non-chromate primer paint systems to evaluate the effects of the coatings on fatigue crack growth rates. The tests were conducted in lab air and sea water environments for each of the coating systems. Standard E399 CT specimens were tested to determine the influence level of environmentally assisted cracking (corrosion fatigue) on crack growth rates and cyclic count to prescribed pre-crack and final crack lengths. Increasing stress range (Δ K) tests were conducted at 10 Hz in the range of 6.5 to 26.5 MPa. It was determined that the coated specimens exhibited a 12% shorter total life, on average, than the bare specimens for the lab air cases. In the case of salt water exposure, the coated specimens exhibited approximately 10% life increase over the bare specimens. The number of cycles to the 2.54 mm pre-crack length for the coated specimens was all less than the cycle count for the bare tests. In each case (coated or bare), there was an increased growth rate at the lower stress ranges in the salt water environment, with the chromate system case displaying the smallest change (increase). It can be concluded that the coated specimens initiate cracks and propagate faster than the bare specimens for short cracks at low stress range, but the environmental influence on the specimens is quickly overshadowed as the cracks elongate and the rate of growth increases. The coated specimens exhibited a higher total life cycle count to final crack length for this testing.

  18. Arsenate and phosphate adsorption in relation to oxides composition in soils: LCD modeling.

    Science.gov (United States)

    Cui, Yanshan; Weng, Liping

    2013-07-01

    The pH dependent solid-solution distribution of arsenate and phosphate in five Dutch agricultural soil samples was measured in the pH range 4-8, and the results were interpreted using the LCD (ligand and charge distribution) adsorption modeling. The pH dependency is similar for both oxyanions, with a minimum soluble concentration observed around pH 6-8. This pH dependency can be successfully described with the LCD model and it is attributed mainly to the synergistic effects from Ca adsorption. The solubility of phosphate is much lower than that of arsenate. This big difference cannot be sufficiently explained by the reduction of small amount of As(V) into As(III), neither by slow desorption/adsorption. The difference between phosphate and arsenate in their solid-solution distribution becomes larger with the increase of aluminum (hydr)oxides (Al-oxides) contribution to the total amount of metal (Al and Fe) (hydr)oxides. The influence of Al-oxides is much larger than its relative amount extracted from the soils. When Al-oxides account for >40% of the soil oxides, the whole adsorbents behave apparently similarly to that of pure Al-oxides. These results indicated that surface coating and substitution may have modified significantly oxyanion adsorption to Fe-oxides in soils, and how to account for this complexity is a challenge for geochemical modeling.

  19. Novel phytase from Pteris vittata resistant to arsenate, high temperature, and soil deactivation.

    Science.gov (United States)

    Lessl, Jason T; Ma, Lena Q; Rathinasabapathi, Bala; Guy, Charles

    2013-03-01

    Arsenate interferes with enzymatic processes and inhibits inorganic phosphorus (Pi) uptake in many plants. This study examined the role of phytase and phosphatase in arsenate tolerance and phosphorus (P) acquisition in the arsenic hyperaccumulator Pteris vittata . Enzyme-mediated hydrolysis of phytate in P. vittata extracts was not inhibited by arsenate at 5 mM or by heating at 100 °C for 10 min. Root exudates of P. vittata exhibited the highest phytase activity (18 nmol Pi mg(-1) protein min(-1)) when available P was low, allowing its growth on media amended with phytate as the sole source of P. Phosphorus concentration in P. vittata gametophyte tissue grown on phytate was equivalent to plants grown with inorganic phosphate at 2208 mg kg(-1), and arsenic was increased from 1777 to 2630 mg kg(-1). After 2 h of mixing with three soils, P. vittata phytase retained more activity, decreasing from ∼ 26 to ∼ 25 nmol Pi mg(-1) protein min(-1), whereas those from Pteris ensiformis and wheat decreased from ∼ 18 to ∼ 1 nmol Pi mg(-1) protein min(-1). These results suggest P. vittata has a uniquely stable phytase enabling its P acquisition in P-limiting soil environments. Furthermore, the P. vittata phytase has potential use as a soil amendment, a transgenic tool, or as a feed additive supplement, reducing the need for nonrenewable, polluting P fertilizers.

  20. Arsenate Adsorption Mechanism on Nano-ball Allophane by Langmuir Adsorption Equation

    Directory of Open Access Journals (Sweden)

    Elvis Anup Shukla

    2011-12-01

    Full Text Available Arsenic is considered as the synonym of death. High toxicity of arsenic in nature is a worldwide problem and often referred to as 20th -21st century calamity. High arsenic concentration has been reported recently from USA, China, Chile, Bangladesh, Taiwan, Mexico, Argentina, Poland, Canada, Hungry, Japan and India. Among all the countries Bangladesh and West Bengal of India are at the high risk. Thus arsenic disposal became an important task. In the present study an attempt is made to study the adsorption of toxic arsenic on allophanes.The adsorption of arsenate on a low Si/Al ratio allophane (KyP was found to be very effective in reducing the amount of arsenic below the toxic level. The examination of adsorption isotherm of arsenate on allophane by Langmuir theory indicated that arsenate adsorption increased with the increasing bulk solution concentration. The observed increase in the pH can be attributed to the ligand exchange on allophane. Aluminol groups, Al-OH or Al-OH2, on allophane are responsible for the adsorption in soil.

  1. Fluctuations in the prevalence of chromate allergy in Denmark and exposure to chrome-tanned leather

    DEFF Research Database (Denmark)

    Carøe, Caroline; Andersen, Klaus E; Thyssen, Jacob P;

    2010-01-01

    A recent Danish study showed a significant increase in the prevalence of chromate contact allergy after the mid-1990s, probably as a result of exposure to leather products.......A recent Danish study showed a significant increase in the prevalence of chromate contact allergy after the mid-1990s, probably as a result of exposure to leather products....

  2. Performance Comparison of Steam-Based and Chromate Conversion Coatings on Aluminum Alloy 6060

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    2015-01-01

    In this study, oxide layers generated on aluminum alloy 6060(UNS A96060) using a steam-based process were compared with conventional chromate and chromate-phosphate conversion coatings. Chemical composition and microstructure of the conversion coatings were investigated and their corrosion...

  3. Chromatism compensation in wide-band nulling interferometry for exoplanet detection

    NARCIS (Netherlands)

    Spronck, J.; Pereira, S.F.; Braat, J.J.M.

    2006-01-01

    We introduce the concept of chromatism compensation in nulling interferometry that enables a high rejection ratio in a wide spectral band. Therefore the achromaticity condition considered in most nulling interferometers can be relaxed. We show that this chromatism compensation cannot be applied to a

  4. Chromatic dispersion of liquid crystal infiltrated capillary tubes and photonic crystal fibers

    DEFF Research Database (Denmark)

    Rasmussen, Per Dalgaard; Lægsgaard, Jesper; Bang, Ole

    2006-01-01

    We consider chromatic dispersion of capillary tubes and photonic crystal fibers infiltrated with liquid crystals. A perturbative scheme for inclusion of material dispersion of both liquid crystal and the surrounding waveguide material is derived. The method is used to calculate the chromatic disp...

  5. Flexible OFDM-based access systems with intrinsic function of chromatic dispersion compensation

    Science.gov (United States)

    Konishi, Tsuyoshi; Murakawa, Takuya; Nagashima, Tomotaka; Hasegawa, Makoto; Shimizu, Satoshi; Hattori, Kuninori; Okuno, Masayuki; Mino, Shinji; Himeno, Akira; Uenohara, Hiroyuki; Wada, Naoya; Cincotti, Gabriella

    2015-12-01

    Cost-effective and tunable chromatic dispersion compensation in a fiber link are still an open issue in metro and access networks to cope with increasing costs and power consumption. Intrinsic chromatic dispersion compensation functionality of optical fractional orthogonal frequency division multiplexing is discussed and experimentally demonstrated using dispersion-tunable transmitter and receiver based on wavelength selective switching devices.

  6. Time-multiplexed chromatic-controlled axial diffractive optical elements

    Science.gov (United States)

    Martínez-García, Antonio

    2010-07-01

    Programmable diffractive optical elements (DOEs) with axial response have many interesting applications, including diffractive lenses, axicons, and optical tweezers. In all these cases, it is essential to properly select the modulation configuration of the spatial light modulator (SLM) where the DOE is displayed, in order to avoid the undiffracted zero order component that appears on axis and overlaps the desired axial response. However, in general, the chromatic dispersion in liquid crystal SLMs prevents the cancellation of the zero order for a broadband light source, thus limiting the possibilities for polychromatic programmable axial DOEs. We operate a ferroelectric liquid crystal on silicon display with polychromatic illumination and with a specific polarization configuration that provides binary π-phase modulation for all wavelengths. Since this type of modulation cancels the undiffracted zero order, we use this SLM to display DOEs with axial response. Moreover, chromatic control is achieved by time-multiplexing sequences of properly scaled DOEs with the corresponding selection of the input wavelength by means of an electronically controlled color-filter wheel. The presented experimental results include wavelength-controlled diffraction gratings, axicons, and vortex-producing lenses.

  7. Generalized Ramsey numbers for paths in 2-chromatic graphs

    Directory of Open Access Journals (Sweden)

    R. Meenakshi

    1986-01-01

    Full Text Available Chung and Liu have defined the d-chromatic Ramsey number as follows. Let 1≤d≤c and let t=(cd. Let 1,2,…,t be the ordered subsets of d colors chosen from c distinct colors. Let G1,G2,…,Gt be graphs. The d-chromatic Ramsey number denoted by rdc(G1,G2,…,Gt is defined as the least number p such that, if the edges of the complete graph Kp are colored in any fashion with c colors, then for some i, the subgraph whose edges are colored in the ith subset of colors contains a Gi. In this paper it is shown that r23(Pi,Pj,Pk=[(4k+2j+i−2/6] where i≤j≤k

  8. Detection of chromatic microlensing in Q 2237+0305 A

    CERN Document Server

    Mosquera, A M; Mediavilla, E

    2008-01-01

    We present narrow band images of the gravitational lens system Q~2237+0305 made with the Nordic Optical Telescope in eight different filters covering the wavelength interval 3510-8130 \\AA. Using PSF photometry fitting we have derived the difference in magnitude vs. wavelength between the 4 images of Q~2237+0305. At $\\lambda=4110$ \\AA, the wavelength range covered by the Str\\"omgren-v filter coincides with the position and width of the CIV emission line. This allows us to determine the existence of microlensing in the continuum and not in the emission lines for two images of the quasar. Moreover the brightness of image A shows a significant variation with wavelength which can only be explained as consequence of chromatic microlensing. To perform a complete analysis of this chromatic event our observations were used together with OGLE light curves. Both data sets can not be reproduced by the simple phenomenology described under the caustic crossing approximation; using more realistic representations of microlen...

  9. High Chromaticity Aluminum Plasmonic Pixels for Active Liquid Crystal Displays.

    Science.gov (United States)

    Olson, Jana; Manjavacas, Alejandro; Basu, Tiyash; Huang, Da; Schlather, Andrea E; Zheng, Bob; Halas, Naomi J; Nordlander, Peter; Link, Stephan

    2016-01-26

    Chromatic devices such as flat panel displays could, in principle, be substantially improved by incorporating aluminum plasmonic nanostructures instead of conventional chromophores that are susceptible to photobleaching. In nanostructure form, aluminum is capable of producing colors that span the visible region of the spectrum while contributing exceptional robustness, low cost, and streamlined manufacturability compatible with semiconductor manufacturing technology. However, individual aluminum nanostructures alone lack the vivid chromaticity of currently available chromophores because of the strong damping of the aluminum plasmon resonance in the visible region of the spectrum. In recent work, we showed that pixels formed by periodic arrays of Al nanostructures yield far more vivid coloration than the individual nanostructures. This progress was achieved by exploiting far-field diffractive coupling, which significantly suppresses the scattering response on the long-wavelength side of plasmonic pixel resonances. In the present work, we show that by utilizing another collective coupling effect, Fano interference, it is possible to substantially narrow the short-wavelength side of the pixel spectral response. Together, these two complementary effects provide unprecedented control of plasmonic pixel spectral line shape, resulting in aluminum pixels with far more vivid, monochromatic coloration across the entire RGB color gamut than previously attainable. We further demonstrate that pixels designed in this manner can be used directly as switchable elements in liquid crystal displays and determine the minimum and optimal numbers of nanorods required in an array to achieve good color quality and intensity. PMID:26639191

  10. Chromatic alteration on marble surfaces analysed by molecular biology tools

    Directory of Open Access Journals (Sweden)

    Franco Palla

    2007-07-01

    Full Text Available The patina represents a superficial natural alteration of the constituting matter of the work of art. It emerges from the natural and usual stabilization process that the materials of the surface undergo because of the interaction with outdoor agents characterizing the surrounding environment. Besides, it is not linked to an obvious phenomenon of degradation that can be noticed through the change in the original colour of the matter. This is what we intend when we talk about biological patina usually generated by macro and/or micro-organic colonization (fungi, bacteria, alga which contributes to surface bio-deterioration and thus lead to the formation of orange, red or even brown and dark pigmented areas. The presence of chromatic alterations (rose-coloured areas, as a consequence of bacterial colonization, was most particularly pointed out in different sites, such as in the marble slabs on the facades of both the Cathedral of Siena (Duomo di Siena and the Certosa of Pavia. The present study shows an example of chromatic alteration of the surface of marble works due to bacterial colonization.

  11. Sodium arsenate induce changes in fatty acids profiles and oxidative damage in kidney of rats.

    Science.gov (United States)

    Kharroubi, Wafa; Dhibi, Madiha; Mekni, Manel; Haouas, Zohra; Chreif, Imed; Neffati, Fadoua; Hammami, Mohamed; Sakly, Rachid

    2014-10-01

    Six groups of rats (n = 10 per group) were exposed to 1 and 10 mg/l of sodium arsenate for 45 and 90 days. Kidneys from treated groups exposed to arsenic showed higher levels of trans isomers of oleic and linoleic acids as trans C181n-9, trans C18:1n-11, and trans C18:2n-6 isomers. However, a significant decrease in eicosenoic (C20:1n-9) and arachidonic (C20:4n-6) acids were observed in treated rats. Moreover, the "Δ5 desaturase index" and the saturated/polyunsaturated fatty acids ratio were increased. There was a significant increase in the level of malondialdehyde at 10 mg/l of treatment and in the amount of conjugated dienes after 90 days (p < 0.05). Significant kidney damage was observed at 10 mg/l by increase of plasma marker enzymes. Histological studies on the ultrastructure changes of kidney supported the toxic effect of arsenate exposure. Arsenate intoxication activates significantly the superoxide dismutase at 10 mg/l for 90 days, whereas the catalase activity was markedly inhibited in all treated groups (p < 0.05). In addition, glutathione peroxidase activity was significantly increased at 45 days and dramatically declined after 90 days at 10 mg/l (p < 0.05). A significant increase in the level of glutathione was marked for the groups treated for 45 and 90 days at 1 mg/l followed by a significant decrease for rats exposed to 10 mg/l for 90 days. An increase in the level of protein carbonyl was observed in all treated groups (p < 0.05). In conclusion, the present study provides evidence for a direct effect of arsenate on fatty acid (FA) metabolism which concerns the synthesis pathway of n-6 polyunsaturated fatty acids and leads to an increase in the trans FAs isomers. Therefore, FA-induced arsenate kidney damage could contribute to trigger kidney cancer. PMID:24920263

  12. Refractive and diffractive neutron optics with reduced chromatic aberration

    DEFF Research Database (Denmark)

    Poulsen, Stefan Othmar; Poulsen, Henning Friis; Bentley, P.M.

    2014-01-01

    by the use of optics for focusing and imaging. Refractive and diffractive optical elements, e.g. compound refractive lenses and Fresnel zone plates, are attractive due to their low cost, and simple alignment. These optical elements, however, suffer from chromatic aberration, which limit their effectiveness...... to highly monochromatic beams. This paper presents two novel concepts for focusing and imaging non-monochromatic thermal neutron beams with well-known optical elements: (1) a fast mechanical transfocator based on a compound refractive lens, which actively varies the number of individual lenses in the beam...... path to focus and image a time-of-flight beam, and (2) a passive optical element consisting of a compound refractive lens, and a Fresnel zone plate, which may focus and image both continuous and pulsed neutron beams....

  13. A generalization of the Birthday problem and the chromatic polynomial

    CERN Document Server

    Fadnavis, Sukhada

    2011-01-01

    The birthday paradox states that there is at least half a chance that some two out of twenty-three randomly chosen people will share the same birth date. The calculation for this problem assumes that all birth dates are equally likely. We consider the following two modifications of this question. What if the distribution of birth dates is non-uniform and possibly even unknown? Further, what if we focus on birthdays shared by two friends rather than any two people? In this paper we present some of our results and conjectures in this generalized setting. We will also show how these results are related to the Stanley-Stembridge poset chain chromatic conjecture and the `shameful conjecture', two famous conjectures in combinatorics.

  14. Chromate-free corrosion resistant talc coatings for aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Buchheit, R G [Sandia National Labs., Albuquerque, NM (United States); Stoner, G E [Virginia Univ., Charlottesville, VA (United States). Dept. of Materials Science and Engineering

    1992-01-01

    Passivity developed by immersion in an alkaline Li salt solution is retained when the Al surface is exposed to an aggressive solution like aerated NaCl. A process for coating Al was developed using a method similar to the chromate conversion process, imparts appreciable corrosion resistance, but does not use or produce hazardous chemicals. Coatings are formed by immersion in 0.1 M Li carbonate solution whose pH is adjusted to 11.5-12.0 by LiOH additions. Immersion times of 1.5 to 90 min were used to produce talc coatings; best time is 15 min. Increased corrosion resistance is obtained if the coating is sealed by elevated temperature treatment in air or distilled water.

  15. Some relations between rank, chromatic number and energy of graphs

    International Nuclear Information System (INIS)

    The energy of a graph G is defined as the sum of the absolute values of all eigenvalues of G and denoted by E(G). Let G be a graph and rank(G) be the rank of the adjacency matrix of G. In this paper we characterize all the graphs with E(G) = rank(G). Among other results we show that apart from a few families of graphs, E(G) ≥ 2max(χ(G), n - χ(G--bar)), where G-bar and χ(G) are the complement and the chromatic number of G, respectively. Moreover some new lower bounds for E(G) in terms of rank(G) are given. (author)

  16. Chromatic perception of non-invasive lighting of cave paintings

    Science.gov (United States)

    Zoido, Jesús; Vazquez, Daniel; Álvarez, Antonio; Bernabeu, Eusebio; García, Ángel; Herraez, Juán A.; del Egido, Marian

    2009-08-01

    This work is intended to deal with the problems which arise when illuminanting Paleolithic cave paintings. We have carried out the spectral and colorimetric characterization of some paintings located in the Murcielagos (bats) cave (Zuheros, Córdoba, Spain). From this characterization, the chromatic changes produced under different lighting conditions are analysed. The damage function is also computed for the different illuminants used. From the results obtained, it is proposed an illuminant whose spectral distribution diminishes the damage by minimizing the absorption of radiation and optimises the color perception of the paintings in this cave. The procedure followed in this study can be applied to optimise the lighting systems used when illuminating any other art work

  17. Chromate reduction and heavy metal fixation in soil

    International Nuclear Information System (INIS)

    In situ reduction of chromates and the fixation of the metals Cr, Pb, Zn, Cu, Cd and Ni in soil was investigated using Fe II and soluble silica. Fe II fulfills two functions. It reduces chromates (CrVI) at soil pH to CrIII and the reaction products, Fe(OH)3 and Cr(OH)3, coprecipitate/adsorb heavy metals. In the absence of CrVI iron is added as FeIII. Destabilized silica also fulfills two functions. It reacts with the metal and metal hydroxides and reduces the soil permeability. The leaching rate (mg/m2s) of a metal is the product of leachate flow rate (ell/M2s) and the leachate concentration (mg/ell). The leachate flow rate is directly proportional to the hydraulic coefficient (Darcy's Law). Treatment with destabilized silica reduces the hydraulic coefficient of virgin soil (Kh = 10-2...10-4) to Kh=10-7 (cm/s) resulting in a flow rate reduction of 3--5 orders of magnitude. Iron plus silica treatment results in a leachate concentration reduction of up to 2 orders of magnitude (Cr:95--99%;Pb:99%;Zn 95--99%; Cd:93--99%; Ni:75--94%). Combined effect of flow rate reduction and leachate concentration reduction results in a potential leaching rate reduction of five to seven orders of magnitude. Iron-silica treatment may be developed into an efficient containment technology, provided the silica gel integrity does not change with time

  18. Cloning, nucleotide sequence, and expression of the chromate resistance determinant of Pseudomonas aeruginosa plasmid pUM505.

    OpenAIRE

    Cervantes, C.; Ohtake, H; Chu, L.; Misra, T K; Silver, S

    1990-01-01

    The chromate resistance determinant of Pseudomonas aeruginosa plasmid pUM505 was cloned into broad-host-range vector pSUP104. The hybrid plasmid containing an 11.1-kilobase insert conferred chromate resistance and reduced uptake of chromate in P. aeruginosa PAO1. Resistance to chromate was not expressed in Escherichia coli. Contiguous 1.6- and 6.3-kilobase HindIII fragments from this plasmid hybridized to pUM505 but not to P. aeruginosa chromosomal DNA and only weakly to chromate resistance p...

  19. Stabilization of arsenic and chromium polluted soils using water treatment residues

    OpenAIRE

    Nielsen, Sanne Skov; Jakobsen, Rasmus; Kjeldsen, Peter

    2013-01-01

    Chromated Copper Arsenate (CCA) is a mixture of arsenic, chromium and copper salts which have widely been used for impregnation of wood. World-wide many contaminated sites and brownfields exist, where wood impregnation with CCA has taken place, resulting in soil contamination and leaching of contaminants. Arsenic, chromium and copper cannot be degraded and existing methods for cleaning the soil are rarely used as they are expensive and technically demanding.Chemical stabilization of polluted ...

  20. Characterization of flue gas, fly ash, aerosol and deposit compositions as a function of waste composition and grate operation

    DEFF Research Database (Denmark)

    Pedersen, Anne Juul; Zeuthen, Frederik Jacob; Frandsen, Flemming;

    2007-01-01

    metals, was then mixed with the reference fuel in the individual test runs. The dedicated waste fractions comprised NaCl (road salt), batteries, automotive shredder waste, CCA (Copper-Chromate-Arsenate)-impregnated wood, PVC plastics, and (leather) shoes. Test runs with varying operational parameters, e...

  1. Mitigating Impacts Of Arsenic Contaminated Materials Via Two (2) Stabilization Methods Based On Polymeric And Cement Binders

    Science.gov (United States)

    The primary objective of this study was to evaluate the performance of two selected chemical stabilization and solidification (S/S) techniques to treat three types of arsenic-contaminated wastes 1) chromated copper arsenate (CCA) wood treater waste, 2) La Trinidad Mine tailings, ...

  2. MANAGING SOURCES TO REDUCE RISK IN AND AROUND THE INDOOR ENVIRONMENT: IMPACT OF COATINGS ON DISLODGEABLE ARSENIC ON THE SURFACES OF CCA-TREATED WOOD

    Science.gov (United States)

    Due to the potential for ingestion of chromated copper arsenate (CCA) by the hand-to-mouth activities of young children who contact CCA treated wood, EPA has used wipe samples to study the potential benefits of paint-like coatings on CCA treated wood. Citizens who may be concern...

  3. A PROBABILISTIC EXPOSURE ASSESSMENT FOR CHILDREN WHO CONTACT CCA-TREATED PLAYSETS AND DECKS USING THE STOCHASTIC HUMAN EXPOSURE AND DOSE SIMULATION (SHEDS) MODEL FOR THE WOOD PRESERVATIVE EXPOSURE SCENARIO

    Science.gov (United States)

    The U.S. Environmental Protection Agency has conducted a probabilistic exposure and dose assessment on the arsenic (As) and chromium (Cr) components of Chromated Copper Arsenate (CCA) using the Stochastic Human Exposure and Dose Simulation model for wood preservatives (SHEDS-Wood...

  4. CCA-TREATED WOOD DISPOSED IN LANDFILLS AND LIFE-CYCLE TRADE-OFFS WITH WASTE-TO-ENERGY AND MSW LANDFILL DISPOSAL

    Science.gov (United States)

    Chromated copper arsenate (CCA) treated wood is a preservative treated wood construction product that grew in use in the 1970s for both residential and industrial applications. In the U.S. CCA-treated wood is disposed primarily within landfills, however some of the wood is combu...

  5. Poisoned Playgrounds: Arsenic in "Pressure-Treated" Wood.

    Science.gov (United States)

    Sharp, Renee; Walker, Bill

    This study of 180 pressure-treated wood samples shows that treated wood is a much greater source of arsenic exposure for children than arsenic-contaminated drinking water. The report determines that an average 5-year-old, playing less than 2 weeks on a chromated-copper-arsenate-treated (CCA) wood play set would exceed the lifetime cancer risk…

  6. USEPA SHEDS MODEL: METHODOLOGY FOR EXPOSURE ASSESSMENT FOR WOOD PRESERVATIVES

    Science.gov (United States)

    A physically-based, Monte Carlo probabilistic model (SHEDS-Wood: Stochastic Human Exposure and Dose Simulation model for wood preservatives) has been applied to assess the exposure and dose of children to arsenic (As) and chromium (Cr) from contact with chromated copper arsenat...

  7. Repeated exposures to cobalt or chromate on the hands of patients with hand eczema and contact allergy to that metal

    DEFF Research Database (Denmark)

    Nielsen, N H; Kristiansen, J; Borg, L;

    2000-01-01

    The present study aimed at evaluating the effects of daily repeated exposures to low cobalt or chromate concentrations on the hands of patients with hand eczema and cobalt or chromate allergy. For 2 weeks, the patients immersed a finger for 10 min daily into the appropriate metal salt solution......-sensitive patients. During the exposure period, accumulation of cobalt or chromate in the nail was demonstrated. Standardization of chemical methods of quantification of skin exposure to allergens, combined with experimental exposure studies in patients with specific contact allergy, will increase the possibility...... in water. During the 1st week, this was a 10 or 50 mg/l cobalt concentration or a 10 mg/l chromate concentration, and, during the 2nd week, a 100 or 200 mg/l cobalt concentration or a 100 mg/l chromate concentration. This regimen elicited a flare of hand eczema only in the chromate-exposed chromate...

  8. The Star Chromatic Numbers of Some Planar Graphs Derived from Wheels

    Institute of Scientific and Technical Information of China (English)

    LI De Ming

    2002-01-01

    The notion of the star chromatic number of a graph is a generalization of the chromaticnumber. In this paper, we calculate the star chromatic numbers of three infinite families of planargraphs. The first two families are derived from a 3-or 5-wheel by subdivisions, their star chromaticnumbers being 2+2/(2n + 1), 2+3/(3n + 1) and 2+3/(3n - 1), respectively. The third family of planargraphs are derived from n odd wheels by Hajos construction with star chromatic numbers 3 + 1/n,which is a generalization of one result of Gao et al.

  9. A Genetic Algorithm for Chromaticity Correction in Diffraction Limited Storage Rings

    CERN Document Server

    Ehrlichman, Michael

    2016-01-01

    An multi-objective genetic algorithm is developed for optimizing nonlinearities in diffraction limited storage rings. This algorithm determines sextupole and octupole strengths for chromaticity correction that deliver optimized dynamic aperture and beam lifetime. The algorithm makes use of dominance constraints to breed desirable properties into the early generations. The momentum aperture is optimized indirectly by constraining the chromatic tune footprint and optimizing the off-energy dynamic aperture. The result is an effective and computationally efficient technique for correcting chromaticity in a storage ring while maintaining optimal dynamic aperture and beam lifetime. This framework was developed for the Swiss Light Source (SLS) upgrade project.

  10. Flat Supercontinuum Generated in a Single-Mode Optical Fibre with a New Chromatic Dispersion Profile

    Institute of Scientific and Technical Information of China (English)

    XU Yong-Zhao; REN Xiao-Min; ZHANG Xia; HUANG Yong-Qing; XU Wen-Cheng

    2005-01-01

    @@ A new chromatic dispersion profile of a single-mode opticalfibre is proposed for generating a supercontinuum with a flatly broadened spectrum. The chromatic dispersion D( λ, z) is a convex function of wavelengths and has no zero-dispersion wavelengths over the whole part of thefibre as D(λ, z) is negative. It is shown that the flat supercontinuum spectrum is obtained when the pump wavelength is set in the vicinity of the wavelength at which the peak chromatic dispersion is near zero and the strong residual pump component is eliminated.

  11. Characterization and genomic analysis of chromate resistant and reducing Bacillus cereus strain SJ1

    Directory of Open Access Journals (Sweden)

    He Minyan

    2010-08-01

    Full Text Available Abstract Background Chromium is a toxic heavy metal, which primarily exists in two inorganic forms, Cr(VI and Cr(III. Chromate [Cr(VI] is carcinogenic, mutational, and teratogenic due to its strong oxidizing nature. Biotransformation of Cr(VI to less-toxic Cr(III by chromate-resistant and reducing bacteria has offered an ecological and economical option for chromate detoxification and bioremediation. However, knowledge of the genetic determinants for chromate resistance and reduction has been limited so far. Our main aim was to investigate chromate resistance and reduction by Bacillus cereus SJ1, and to further study the underlying mechanisms at the molecular level using the obtained genome sequence. Results Bacillus cereus SJ1 isolated from chromium-contaminated wastewater of a metal electroplating factory displayed high Cr(VI resistance with a minimal inhibitory concentration (MIC of 30 mM when induced with Cr(VI. A complete bacterial reduction of 1 mM Cr(VI was achieved within 57 h. By genome sequence analysis, a putative chromate transport operon, chrIA1, and two additional chrA genes encoding putative chromate transporters that likely confer chromate resistance were identified. Furthermore, we also found an azoreductase gene azoR and four nitroreductase genes nitR possibly involved in chromate reduction. Using reverse transcription PCR (RT-PCR technology, it was shown that expression of adjacent genes chrA1 and chrI was induced in response to Cr(VI but expression of the other two chromate transporter genes chrA2 and chrA3 was constitutive. In contrast, chromate reduction was constitutive in both phenotypic and gene expression analyses. The presence of a resolvase gene upstream of chrIA1, an arsenic resistance operon and a gene encoding Tn7-like transposition proteins ABBCCCD downstream of chrIA1 in B. cereus SJ1 implied the possibility of recent horizontal gene transfer. Conclusion Our results indicate that expression of the chromate

  12. Arsenic accumulation by the aquatic fern Azolla: comparison of arsenate uptake, speciation and efflux by A. caroliniana and A. filiculoides.

    Science.gov (United States)

    Zhang, Xin; Lin, Ai-Jun; Zhao, Fang-Jie; Xu, Guo-Zhong; Duan, Gui-Lan; Zhu, Yong-Guan

    2008-12-01

    This study investigates As accumulation and tolerance of the aquatic fern Azolla. Fifty strains of Azolla showed a large variation in As accumulation. The highest- and lowest-accumulating ferns among the 50 strains were chosen for further investigations. Azolla caroliniana accumulated two times more As than Azolla filiculoides owing to a higher influx velocity for arsenate. A. filiculoides was more resistant to external arsenate due to a lower uptake. Both strains showed a similar degree of tolerance to internal As. Arsenate and arsenite were the dominant As species in both Azolla strains, with methylated As species accounting for Azolla in paddy fields to reduce As transfer from soil and water to rice should be further evaluated. PMID:18457908

  13. Joint IQ Skew and Chromatic Dispersion Estimation for Coherent Optical Communication Receivers

    DEFF Research Database (Denmark)

    Medeiros Diniz, Júlio César; Porto da Silva, Edson; Piels, Molly;

    2016-01-01

    A low-complexity scanning method for joint estimation of receiver IQ skew and chromatic dispersion is proposed. This method shows less than 1 ps skew error for a 1200-km 32-GBd DP-16QAM optical transmission experiment....

  14. Measurement of Stratospheric Chromatic Scintillation with the AMON-RA Balloonborne Spectrometer.

    Science.gov (United States)

    Renard, J B; Dalaudier, F; Hauchecorne, A; Robert, C; Lemaire, T; Pirre, M; Bertaux, J L

    2001-08-20

    The balloonborne instrument AMON (which is a French acronym for Absorption par les Minoritaires Ozone et NO(x)) has been modified to record chromatic scintillation during stellar occultation by the Earth's atmosphere. A 14-channel spectrophotometer with a sampling rate of 10 Hz was added, and the modified instrument, AMON-RA, performed successful measurements of the setting star Alnilam during the third European Stratospheric Experiment on Ozone (THESEO) project. Unambiguous records of the chromatic scintillation were obtained, to our knowledge for the first time from above the atmosphere, and some of its basic properties are reported. The properties of atmospheric structures that are responsible for this chromatic scintillation were found to be consistent with those of previous monochromatic measurements performed from space. A maximum chromatic delay of 2.5 s was observed for widely different wavelengths.

  15. Measuring chromatic aberrations in imaging systems using plasmonic nano-particles

    CERN Document Server

    Gennaro, Sylvain D; Maier, Stefan A; Oulton, Rupert F

    2015-01-01

    Chromatic aberration in optical systems arises from the wavelength dependence of a glass's refractive index. Polychromatic rays incident upon an optical surface are refracted at slightly different angles and in traversing an optical system follow distinct paths creating images displaced according to color. Although arising from dispersion, it manifests as a spatial distortion correctable only with compound lenses with multiple glasses and accumulates in complicated imaging systems. While chromatic aberration is measured with interferometry, simple methods are attractive for their ease of use and low cost. In this letter we retrieve the longitudinal chromatic focal shift of high numerical aperture (NA) microscope objectives from the extinction spectra of metallic nanoparticles within the focal plane. The method is accurate for high NA objectives with apochromatic correction, and enables rapid assessment of the chromatic aberration of any complete microscopy systems, since it is straightforward to implement

  16. Correction of chromatic aberrations at television registration of image through protective viewing systems

    Science.gov (United States)

    Kulyas, Oleg L.; Nikitin, Konstantin A.

    2016-03-01

    Ways of chromatic aberration in images are examined and analyzed which are generated at television supervision through protective glasses of a considerable thickness. The results of experimental check up of the given method of correction is introduced and described.

  17. Psychophysical Evaluation of Achromatic and Chromatic Vision of Workers Chronically Exposed to Organic Solvents

    OpenAIRE

    Luiz Carlos de Lima Silveira; Dora Fix Ventura; Lauro José Barata de Lima; Cláudio Eduardo Correa Teixeira; Anderson Raiol Rodrigues; Eliza Maria da Costa Brito Lacerda; Monica Gomes Lima

    2012-01-01

    The purpose of this paper was to evaluate achromatic and chromatic vision of workers chronically exposed to organic solvents through psychophysical methods. Thirty-one gas station workers (31.5 ± 8.4 years old) were evaluated. Psychophysical tests were achromatic tests (Snellen chart, spatial and temporal contrast sensitivity, and visual perimetry) and chromatic tests (Ishihara's test, color discrimination ellipses, and Farnsworth-Munsell 100 hue test—FM100). Spatial contrast sensitivities of...

  18. Suppression of mutants aberrant in light intensity responses of complementary chromatic adaptation.

    OpenAIRE

    Casey, E S; Kehoe, D M; Grossman, A R

    1997-01-01

    Complementary chromatic adaptation is a process in which cyanobacteria alter the pigment protein (phycocyanin and phycoerythrin) composition of their light-harvesting complexes, the phycobilisomes, to help optimize the absorbance of prevalent wavelengths of light in the environment. Several classes of mutants that display aberrant complementary chromatic adaptation have been isolated. One of the mutant classes, designated "blue" or FdB, accumulates high levels of the blue chromoprotein phycoc...

  19. A human spatial-chromatic vision model for evaluating electronic displays

    OpenAIRE

    Lloyd, Charles J. C.

    1990-01-01

    This dissertation examines those attributes of full-color display systems (particularly color matrix displays) which degrade image quality. Based on this analysis, it is suggested that a comprehensive metric should measure image quality in terms of transmitted signal and noise modulation, both achromatic and chromatic. Moreover, it is suggested that these signal and noise measurements be weighted in terms of human spatial-chromatic visual characteristics. A review of extant...

  20. The sandstone's chromatic alteration of the florentine cultural heritage

    Science.gov (United States)

    Vettori, S.; Pecchioni, E.; Cantisani, E.; Ricci, M.; Fratini, F.; Garzonio, C. A.

    2012-04-01

    Pietra Serena is one of the materials more used in Florentine architecture. It is a sandstone that outcrops in the hills north of the city in the municipality of Fiesole and it has been employed mainly for ornamental purposes. This litotype belongs to the the Macigno Formation (Oligocene Upper- Miocene Lower) which consists of beds of turbiditic sandstones separated by pelitic levels which are the finest components of each single turbidity layer. Petrographically, Pietra Serena can be defined as a medium-coarse-grained greywacke made of quartz, feldspars, micas, fragments of metamorphic and magmatic rocks. The clayey matrix is quite abundant, mainly composed by illite, kaolinite and chlorite-vermiculite (present only in some quarries). It is well known that the processes of decay of the sandstones are related to the type of matrix, the amount of cement, the kind of clay minerals and to the pore size distribution, which lead to water infiltrations, swelling of the clay minerals, separation of the clayey matrix, with resulting exfoliation and peeling of the stone artefacts. Pietra Serena has a bluish-grey colour in fresh cut, but many times it is easily oxidized acquiring an ochraceous-reddish brown colour on buildings. Such changes in colour, appear to be due in part to the oxidation of iron, proceeding very quickly from the surface to the inside, though the cohesion is not affected. It is possible to hypothesize that the chromatic changes not necessarily involve a progressive state of alteration of the artefact, but they may often to represents a natural patina acquired with the time. Nevertheless it is necessary to remember that the oxidized layer and its hardness could also be the result of treatments performed in the past. In Florence, several monuments and buildings are affected by such phenomenon, in particular it is possible to note an intense and diffuse reddish colouring on the Pietra Serena utilized for columns and for façade's decorations. In this work

  1. Developmental consequences of in utero sodium arsenate exposure in mice with folate transport deficiencies

    International Nuclear Information System (INIS)

    Previous studies have demonstrated that mice lacking a functional folate binding protein 2 gene (Folbp2-/-) were significantly more sensitive to in utero arsenic exposure than were the wild-type mice similarly exposed. When these mice were fed a folate-deficient diet, the embryotoxic effect of arsenate was further exacerbated. Contrary to expectations, studies on 24-h urinary speciation of sodium arsenate did not demonstrate any significant difference in arsenic biotransformation between Folbp2-/- and Folbp2+/+ mice. To better understand the influence of folate pathway genes on arsenic embryotoxicity, the present investigation utilized transgenic mice with disrupted folate binding protein 1 (Folbp1) and reduced folate carrier (RFC) genes. Because complete inactivation of Folbp1 and RFC genes results in embryonic lethality, we used heterozygous animals. Overall, no RFC genotype-related differences in embryonic susceptibility to arsenic exposure were observed. Embryonic lethality and neural tube defect (NTD) frequency in Folbp1 mice was dose-dependent and differed from the RFC mice; however, no genotype-related differences were observed. The RFC heterozygotes tended to have higher plasma levels of S-adenosylhomocysteine (SAH) than did the wild-type controls, although this effect was not robust. It is concluded that genetic modifications at the Folbp1 and RFC loci confers no particular sensitivity to arsenic toxicity compared to wild-type controls, thus disproving the working hypothesis that decreased methylating capacity of the genetically modified mice would put them at increased risk for arsenic-induced reproductive toxicity

  2. Adsorption of fluoride, phosphate, and arsenate ions on lanthanum- impregnated silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Wasay, S.A.; Haron, M.J.; Tokunaga, S. [National Inst. of Materials and Chemicals Research, Ibaraki (Japan)

    1996-05-01

    A lanthanum-impregnated silica gel has been developed for the removal of fluoride, phosphate, and arsenate ions by adsorption. The interaction between silica gel and lanthanum ion was maximum at a final pH of 6. The removal of fluoride and arsenate ions by adsorption on the lanthanum-impregnated silica gel was more than 99. 9% at neutral pH from initial concentration of 0.55 and 0.2 mmol/L, respectively. The removal of phosphate ion was 95% at an initial concentration of 0.5 mmol/L at neutral pH. Arsenite ion was not adsorbed on the material. The rate of adsorption of the anions followed the first-order reaction and fit in the Lagergren equation. The adsorption of each anion followed the Langmuir isotherm. Other anions such as Cl{sup -}, BR{sup -}, I{sup -}, NO{sub 3}{sup -}, and SO{sub 4}{sup 2-} did not interfere with the adsorption. A column study was conducted for the removal of these anions at a fixed flow rate of 0.5 mL/min at pH approximately 7. These anions were removed by more than 99.9% at initial first or second fraction, and the column was regenerated at pH 8.5. The method was applied for the removal of these anions from synthetic and high-tech industrial wastewaters. 30 refs., 8 figs., 1 tab.

  3. Effects of Chronic Exposure to Sodium Arsenate on Kidney of Rats

    Directory of Open Access Journals (Sweden)

    Namdar Yousofvand

    2015-09-01

    Full Text Available Background: In the present study, histopathological effects of chronic exposure to sodium arsenate in drinkable water were studied on a quantity of organs of rat. Methods: Rats were divided into two groups, group I; served as control group, were main-tained on deionized drinkable water for 2 months, and group II; the study group were given 60 g/ml of sodium arsenate in deionized drinkable water for 2 months. Blood and urine samples from two groups of animals were collected under anesthesia and the animals were sacrificed under deep anesthesia (a-chloralose, 100 mg/kg, I.P. Their kidney, liver, aorta, and heart were dissected out and cleaned of surrounding connective tissue. The organs were kept in formaldehyde (10% for histopathologic examination. Serum and urine samples from two groups were collected and analyzed for arsenic level. Total quantity of arsenic in serum and urine of animal was measured through graphic furnace atomic absorption spectrometry (GF-AAS. Results:Examination with light microscopy did not show any visible structural changes in the aorta, myocardium, and liver of chronic arsenic treated animals.However, a significant effect was observed in the kidneys of chronic arsenic treated rats showing distinct changes in proxi-mal tubular cells. There was high concentration of arsenic in serum and urine of arsenic ex-posed animals (group II significantly (P<0.001. Conclusion:Swollen tubular cells in histopathologic study of kidney may suggest toxic effects of arsenic in the body.

  4. Facile synthesis of highly active hydrated yttrium oxide towards arsenate adsorption.

    Science.gov (United States)

    Yu, Yang; Yu, Ling; Sun, Min; Paul Chen, J

    2016-07-15

    A novel hydrated yttrium oxide adsorbent with high capacity towards the arsenate (As(V)) adsorption was fabricated by a one-step hydrothermal process. Structure analysis identified the hydrated yttrium oxide to be Y2O(OH)4·1.5H2O, which displayed as irregular rods in the range of tens to hundreds of nanometers. The adsorbent exhibited favorable As(V) adsorption efficiency in a wide pH range from 4.0 to 7.0, with the maximum adsorption capacity of 480.2mg-As/g obtained at pH 5.0. Both the kinetics and isotherm studies demonstrated that the adsorption of the As(V) was a monolayer chemical adsorption process, in which the ion exchange between the hydroxyl groups on the hydrated yttrium oxide and arsenate anions played a key role in the uptake of the As(V). During the adsorption, the As(V) anions were replaced the hydroxyl groups and bound to the hydrated yttrium oxide via the linkage of AsOY. The presence of fluoride and phosphate greatly hindered the As(V) uptake on the hydrated yttrium oxide, whereas the bicarbonate, sulfate and humic acid showed insignificant impacts on the removal. PMID:27135142

  5. Effect of inorganic and organic ligands on the sorption/desorption of arsenate on/from Al-Mg and Fe-Mg layered double hydroxides

    Science.gov (United States)

    Caporale, A. G.; Pigna, M.; Dynes, J. J.; Cozzolino, V.; Zhu, J.; Violante, A.

    2012-04-01

    In recent decades, a class of anionic clays known as layered double hydroxides (LDHs) has attracted substantial attention due to the potential use in many applications, such as photochemistry, electrochemistry, polymerization, magnetization and biomedical science. There has also been considerable interest in using LDHs as adsorbents to remove environmental contaminants due to their large surface area, high anion exchange capacity and good thermal stability. We studied the sorption of arsenate on Al-Mg and Fe-Mg layered double hydroxides (easily reproducible at low-cost) as affected by pH and varying concentrations of inorganic (nitrate, nitrite, phosphate, selenite and sulphate) and organic (oxalate and tartrate) ligands, ii) the effect of residence time on the arsenate desorption by these ligands, and iii) the kinetics of arsenate desorption by phosphate. The Fe-Mg-LDH sorbed nearly twice the amount of arsenate compared to the Al-Mg-LDH, due, in part, to its greater surface area and lower degree of crystallinity. Moreover, the Fe-Mg-LDH sorbed more arsenate than phosphate, in contrast to the Al-Mg-LDH, which adsorbed more phosphate than arsenate, probably because of the greater affinity of arsenate than phosphate for Fe sites and, vice versa, the greater affinity of phosphate than arsenate for Al sites. Arsenate sorption onto samples decreased by increasing pH, due, maybe, to the high affinity of hydroxyl ions for LDHs and/or to the value of zero point charge of two sorbents. The rate of decline in the amount of arsenate sorbed was, however, relatively constant, decreasing the fastest for the Fe-Mg-LDH compared to the Al-Mg-LDH. The capacity of ligands to inhibit the fixation of arsenate followed the sequence: nitrate tartrate tartrate anions have a stronger affinity for Fe than Al and for the presence in Fe-Mg-LDH of short-range-ordered materials on which arsenate forms very strong inner-sphere complexes not easily desorbable by competing ligands. The longer the

  6. Pigment chromatic adaptation in Cyclotella caspia Grunow (Bacillariophyta

    Directory of Open Access Journals (Sweden)

    Donato Seiji Abe

    1991-01-01

    Full Text Available The diatom Cyclotella caspia Grunow, isolated from surface waters of the Ubatuba region (São Paulo State, Brazil was submitted to different light spectral distributions for examination of its adaptative response. Growth rate and the photosynthetic pigments chlorophyll a, chlorophyll c, carotenoids and phaeopigments were measured under white, blue and red light of the same intensity (8 and 20 µE.cm-2.s-1. Growth rate increased under blue light while red light increased chl a concentration. The relative proportion of chl a and carotenoids did not change, demonstrating the absence of complementary chromatic adaptation.A diatomácea Cyclotella caspia Grunow, isolada de águas superficiais da região de Ubatuba (Estado de São Paulo, Brasil, foi submetida a diferentes intervalos espectrais de luz com a finalidade de se examinar sua resposta adaptativa. Foram medidos a taxa de crescimento e os pigmentos fotossintéticos clorofila a, clorofila c, carotenóides e feopigmentos, sob luz branca, azul e vermelha de mesmas intensidades (8 e 20 µE.cm-2.s-1. A taxa de crescimento aumentou sob luz azul, sendo que a concentração de clorofila a aumentar sob luz vermelha. A proporção relativa de clα e carotenóides não variou, demonstrando a ausência de adapatação cromática complementar.

  7. Refractive and diffractive neutron optics with reduced chromatic aberration

    Energy Technology Data Exchange (ETDEWEB)

    Poulsen, S.O., E-mail: stefan.poulsen@northwestern.edu [NEXMAP, Department of Physics, Technical University of Denmark, Anker Engelunds Vej 1, 2800 Kgs. Lyngby (Denmark); Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Poulsen, H.F. [NEXMAP, Department of Physics, Technical University of Denmark, Anker Engelunds Vej 1, 2800 Kgs. Lyngby (Denmark); Bentley, P.M. [European Spallation Source ESS AB, Box 176, 221 00 Lund (Sweden)

    2014-12-11

    Thermal neutron beams are an indispensable tool in physics research. The spatial and the temporal resolution attainable in experiments are dependent on the flux and collimation of the neutron beam which remain relatively poor, even for modern neutron sources. These difficulties may be mitigated by the use of optics for focusing and imaging. Refractive and diffractive optical elements, e.g. compound refractive lenses and Fresnel zone plates, are attractive due to their low cost, and simple alignment. These optical elements, however, suffer from chromatic aberration, which limit their effectiveness to highly monochromatic beams. This paper presents two novel concepts for focusing and imaging non-monochromatic thermal neutron beams with well-known optical elements: (1) a fast mechanical transfocator based on a compound refractive lens, which actively varies the number of individual lenses in the beam path to focus and image a time-of-flight beam, and (2) a passive optical element consisting of a compound refractive lens, and a Fresnel zone plate, which may focus and image both continuous and pulsed neutron beams.

  8. The dependence of luminous efficiency on chromatic adaptation.

    Science.gov (United States)

    Stockman, Andrew; Jägle, Herbert; Pirzer, Markus; Sharpe, Lindsay T

    2008-12-15

    We investigated the dependence of luminous efficiency on background chromaticity by measuring 25-Hz heterochromatic flicker photometry (HFP) matches in six genotyped male observers on 21 different 1000-photopic-troland adapting fields: 14 spectral ones ranging from 430 to 670 nm and 7 bichromatic mixtures of 478 and 577 nm that varied in luminance ratio. Each function was analyzed in terms of the best-fitting linear combination of the long- (L) and middle- (M) wavelength sensitive cone fundamentals of A. Stockman and L. T. Sharpe (2000). Taking into account the adapting effects of both the backgrounds and the targets, we found that luminous efficiency between 603 and 535 nm could be predicted by a simple model in which the relative L- and M-cone weights are inversely proportional to the mean cone excitations produced in each cone type multiplied by a single factor, which was roughly independent of background wavelength (and may reflect relative L:M cone numerosity). On backgrounds shorter than 535 nm and longer than 603 nm, the M-cone contribution to luminous efficiency falls short of the proportionality prediction but most likely for different reasons in the two spectral regions.

  9. Perceived no reference image quality measurement for chromatic aberration

    Science.gov (United States)

    Lamb, Anupama B.; Khambete, Madhuri

    2016-03-01

    Today there is need for no reference (NR) objective perceived image quality measurement techniques as conducting subjective experiments and making reference image available is a very difficult task. Very few NR perceived image quality measurement algorithms are available for color distortions like chromatic aberration (CA), color quantization with dither, and color saturation. We proposed NR image quality assessment (NR-IQA) algorithms for images distorted with CA. CA is mostly observed in images taken with digital cameras, having higher sensor resolution with inexpensive lenses. We compared our metric performance with two state-of-the-art NR blur techniques, one full reference IQA technique and three general-purpose NR-IQA techniques, although they are not tailored for CA. We used a CA dataset in the TID-2013 color image database to evaluate performance. Proposed algorithms give comparable performance with state-of-the-art techniques in terms of performance parameters and outperform them in terms of monotonicity and computational complexity. We have also discovered that the proposed CA algorithm best predicts perceived image quality of images distorted with realistic CA.

  10. Effect of the gamma radiation in hydrotalcite with chromates

    International Nuclear Information System (INIS)

    At the moment the generation of radioactive wastes is topic of numerous studies. In this work was retained anionic material, chromates, in hydrotalcite that are anionic exchangers. It was proposed to warm the HT at different temperatures of 600 C up to 1200 C with the purpose of immobilizing the chromium inside the hydrotalcite. To high temperatures (1000 and 1200 C) it was formed one spinel (MgCr2O4) that is a very stable compound. It was found that when increasing the heating temperature, the anions are retained strongly. The immobilization of the Cr was determined through the chromium lixiviation with solutions 1N and 5N of NaCl. Also it was studied the effect of the radiation on the heated materials. The radiation dose used for it was of 1000 and 6000 kGy. The results show that for the calcined samples at 1000 and 1200 C irradiated or no irradiated, the chromium is strongly retained in form of spinels that is the structure formed after the calcination of the material. (Author)

  11. Copper Products Capacity Expansion Stimulate the Copper Consumption

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>The dramatic growth of copper consumption in China can directly be seen from the expansion of copper products capacity.According to sta- tistics,in the past 4 years,the improvement on the balance of trade on copper bar,copper,and copper alloy and copper wire & cable has driven the growth of copper consumption a lot.

  12. Facile synthesis of size-tunable gold nanoparticles by pomegranate (Punica granatum) leaf extract: Applications in arsenate sensing

    International Nuclear Information System (INIS)

    Highlights: ► Pomegranate leaf extracts mediated rapid gold nanoparticle (AuNP) synthesis. ► The phyto-inspired AuNPs were size-tuned and characterized. ► The reducing and capping agents in the extract were identified. ► The nanoparticles reacted specifically with arsenate (V) ions. - Abstract: When pomegranate leaf extracts were incubated with chloroauric acid (HAuCl4), gold nanoparticles (AuNPs) were synthesized. These were characterized by a variety of techniques. With an increasing content of the leaf extract, a gradual decrease in size and an increase in monodispersity were observed. Transmission electron microscope (TEM) images showed that the phyto-fabricated AuNPs were surrounded by an amorphous layer. Gallic acid in the extract mediated the reduction and a natural decapeptide capped the nanostructures. Blocking of thiol groups in the decapeptide cysteine residues caused the nanoparticles to aggregate. On interaction with arsenate (V) ions, the UV–vis spectra of the nanoparticles showed a decrease in intensity and a red-shift. Energy dispersive spectra confirmed the presence of arsenate associated with the AuNPs. Thus, by using these AuNPs, a method for sensing the toxic arsenate ions could be developed

  13. Lead and Arsenic Uptake by Carrots Grown on Five Orchard Soils With History of Lead Arsenate Used

    Science.gov (United States)

    Lead arsenate was used to control codling moth in apple and plum orchards from 1900 to 1960. Consequently, many orchard soils are contaminated with lead (Pb) and arsenic (As). Some of these lands are being used for urban development and vegetable crop production. Both soil Pb and As have become i...

  14. TISSUE DISTRIBUTION OF INORGANIC ARSENIC (AS) AND ITS METHYLATED METABOLITES IN MICE FOLLOWING ORAL ADMINISTRATION OF ARSENATE (ASV)

    Science.gov (United States)

    TISSUE DISTRIBUTION OF INORGANIC ARSENIC (iAs) AND ITS METHYLATED METABOLITES IN MICE FOLLOWING ORAL ADMINISTRATION OF ARSENATE (AsV). E M Kenyon1, L M Del Razo2, and M F Hughes1. 1NHEERL, ORD, US EPA, RTP, NC, USA; 2CINVESTAV-IPN, Mexico City, Mexico.The relationship o...

  15. Arsenic accumulation by the aquatic fern Azolla: Comparison of arsenate uptake, speciation and efflux by A. caroliniana and A. filiculoides

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xin [State Key Lab of Urban and ONAL Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China); Lin Aijun [Department of Environmental Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zhao Fangjie [Soil Science Department, Rothamsted Research, Hertfordshire AL5 2JQ (United Kingdom); Xu Guozhong [Agricultural Ecology Institute, Fujian Academy of Agricultural Sciences, Fuzhou 350013 (China); Duan Guilan [State Key Lab of Urban and ONAL Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China); Zhu Yongguan [State Key Lab of Urban and ONAL Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China); Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361003 (China)], E-mail: ygzhu@rcees.ac.cn

    2008-12-15

    This study investigates As accumulation and tolerance of the aquatic fern Azolla. Fifty strains of Azolla showed a large variation in As accumulation. The highest- and lowest-accumulating ferns among the 50 strains were chosen for further investigations. Azolla caroliniana accumulated two times more As than Azolla filiculoides owing to a higher influx velocity for arsenate. A. filiculoides was more resistant to external arsenate due to a lower uptake. Both strains showed a similar degree of tolerance to internal As. Arsenate and arsenite were the dominant As species in both Azolla strains, with methlyated As species accounting for <5% of the total As. A. filiculoides had a higher proportion of arsenite than A. caroliniana. Both strains effluxed more arsenate than arsenite, and the amount of As efflux was proportional to the amount of As accumulation. The potential of growing Azolla in paddy fields to reduce As transfer from soil and water to rice should be further evaluated. - Arsenic accumulation and efflux differ between strains of the aquatic fern Azolla.

  16. Biosynthesis of phytochelatins and arsenic accumulation in the marine microalga Phaeodactylum tricornutum in response to arsenate exposure.

    Science.gov (United States)

    Morelli, Elisabetta; Mascherpa, Marco Carlo; Scarano, Gioacchino

    2005-12-01

    The arsenate-induced synthesis of phytochelatins (PC), intracellular cysteine-rich metal-binding peptides, and its relationship with toxicity and with As accumulation in the cell have been studied in laboratory cultures of the marine microalga Phaeodactylum tricornutum. The time course of cellular PC and As in short-term exposures showed that the involvement of PC in the As detoxification as well as the pathway of cellular As depend on the extent of As accumulation and on the rate of PC synthesis. At arsenate concentrations causing As accumulation at a rate exceeding that of PC synthesis, cells seem to activate a mechanism of release of As mainly in a chemical form not complexed with PC. At arsenate concentrations at which the synthesis of PC occurs at a rate sufficient to allow a significant portion of As accumulated in the cell to be bound, the fate of cellular As seems to be mainly controlled by PC. The occurrence of these different pathways of As detoxification was discussed to explain the pattern of cellular As and PC in cells grown for three days at growth-inhibitory and at no growth-inhibitory concentration of arsenate.

  17. A green sorbent of esterified egg-shell membrane for highly selective uptake of arsenate and speciation of inorganic arsenic.

    Science.gov (United States)

    Chen, Ming-Li; Gu, Cui-Bo; Yang, Ting; Sun, Yan; Wang, Jian-Hua

    2013-11-15

    Egg-shell membrane (ESM) is a promising adsorbent for heavy metal uptake. However, carboxylic groups on ESM surface barrier arsenic adsorption. Herein, ESM is modified by esterification and the methyl esterified egg-shell membrane (MESM) possesses positive charge within pH 1-9. As a novel green sorbent material, MESM exhibits 200-fold improvement on sorption capacity of arsenate with respect to bare ESM. It presents an ultra-high selectivity of 256:1 toward arsenate against arsenite. At pH 6, 100% sorption efficiency is achieved for 2 μg L(-1) As(V) by 10 mg MESM, while virtually no adsorption of As(III) is observed. This provides great potential for selective sorption of arsenate in the presence of arsenite. By loading 4.0 mL sample within 0.05-5.00 μg L(-1) As(V) followed by elution with 300 μL HCl (1.5 mol L(-1)), a detection limit of 15 ng L(-1) is obtained along with a RSD of 3.5% at 0.5 μg L(-1). Total inorganic arsenic is achieved by converting As(III) to As(V) and following the same sorption process. This procedure is applied for arsenate determination and inorganic arsenic speciation in Hijiki and water samples. The results are confirmed by graphite furnace atomic absorption spectrometry and spiking recovery. PMID:24148462

  18. Facile synthesis of size-tunable gold nanoparticles by pomegranate (Punica granatum) leaf extract: Applications in arsenate sensing

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Ashit; Mahajan, Ketakee; Bankar, Ashok [Institute of Bioinformatics and Biotechnology, University of Pune, Pune 411007 (India); Srikanth, Rapole [Proteomics Laboratory, National Centre for Cell Science, Pune 411007 (India); Kumar, Ameeta Ravi [Institute of Bioinformatics and Biotechnology, University of Pune, Pune 411007 (India); Gosavi, Suresh, E-mail: swg@physics.unipune.ac.in [Department of Physics, University of Pune, Pune 411007 (India); Centre for Sensor Studies, University of Pune, Pune 411007 (India); Zinjarde, Smita, E-mail: smita@unipune.ac.in [Institute of Bioinformatics and Biotechnology, University of Pune, Pune 411007 (India); Centre for Sensor Studies, University of Pune, Pune 411007 (India)

    2013-03-15

    Highlights: ► Pomegranate leaf extracts mediated rapid gold nanoparticle (AuNP) synthesis. ► The phyto-inspired AuNPs were size-tuned and characterized. ► The reducing and capping agents in the extract were identified. ► The nanoparticles reacted specifically with arsenate (V) ions. - Abstract: When pomegranate leaf extracts were incubated with chloroauric acid (HAuCl{sub 4}), gold nanoparticles (AuNPs) were synthesized. These were characterized by a variety of techniques. With an increasing content of the leaf extract, a gradual decrease in size and an increase in monodispersity were observed. Transmission electron microscope (TEM) images showed that the phyto-fabricated AuNPs were surrounded by an amorphous layer. Gallic acid in the extract mediated the reduction and a natural decapeptide capped the nanostructures. Blocking of thiol groups in the decapeptide cysteine residues caused the nanoparticles to aggregate. On interaction with arsenate (V) ions, the UV–vis spectra of the nanoparticles showed a decrease in intensity and a red-shift. Energy dispersive spectra confirmed the presence of arsenate associated with the AuNPs. Thus, by using these AuNPs, a method for sensing the toxic arsenate ions could be developed.

  19. Effects of meso-2,3-dimercaptosuccinic acid (DMSA) on the teratogenicity of sodium arsenate in mice

    Energy Technology Data Exchange (ETDEWEB)

    Bosque, M.A.; Domingo, J.L.; Llobet, J.M. (Univ. of Barcelona, Reus (Spain)); Corbella, J. (Univ. of Barcelona (Spain))

    1991-11-01

    Although the effects of arsenic on mammalian development are now well established, very few data on the protective activity of different chelators against embryotoxicity and teratogenicity of arsenic are available. Chelating agents may interact with teratogen metals to augment or ameliorate their actions. Researchers demonstrated that a single dose of 2,3-dimercaptopropanol (BAL) was capable of affording a degree of protection to arsenate exposed fetal mice. Subcutaneous treatment with 50 mg/kg of BAL 4 hr after arsenate reduced the frequency or severity of malformations compared with the effects of arsenate alone. However, BAL has several drawbacks. In recent years dimercaptosuccinic acid (DMSA) is receiving growing attention in the USA and Western Europe. Results of a number of different investigations in rodents have led to the conclusion that DMSA is much less toxic than BAL. Moreover, DMSA has been reported to be effective in inducing arsenic excretion. In the present study, the protective effects of DMSA in alleviating the embryotoxic and teratogenic effects of sodium arsenate were evaluated in mice.

  20. Separation of copper-64 from copper phthalocyanine

    International Nuclear Information System (INIS)

    The separation of copper-64 from irradiated copper phthalocyanine by Szilard-Chalmers effect is studied. Two methods of separation are used: one of them is based on the dissolution of the irradiated dry compound in concentrated sulfuric acid following its precipitation in water. In the other one the compound is irradiated with water in paste form following treatment with water and hydrochloric acid. The influence of the crystal form of the copper phthalocyanine on the separation yield of copper-64 is shown. Preliminary tests using the ionic exchange technique for purification and changing of copper-64 sulfate to chloride form are carried out. The specific activity using the spectrophotometric technique, after the determination of the copper concentration in solution of copper-64, is calculated. (Author)

  1. Copper Metabolism of Astrocytes

    OpenAIRE

    Ralf Dringen; Scheiber, Ivo F.; Julian FB Mercer

    2013-01-01

    This short review will summarize the current knowledge on the uptake, storage, and export of copper ions by astrocytes and will address the potential roles of astrocytes in copper homeostasis in the normal and diseased brain. Astrocytes in culture efficiently accumulate copper by processes that include both the copper transporter Ctr1 and Ctr1-independent mechanisms. Exposure of astrocytes to copper induces an increase in cellular glutathione (GSH) content as well as synthesis of metallothion...

  2. Phylogenetic analysis of bacterial and archaeal arsC gene sequences suggests an ancient, common origin for arsenate reductase

    Directory of Open Access Journals (Sweden)

    Dugas Sandra L

    2003-07-01

    Full Text Available Abstract Background The ars gene system provides arsenic resistance for a variety of microorganisms and can be chromosomal or plasmid-borne. The arsC gene, which codes for an arsenate reductase is essential for arsenate resistance and transforms arsenate into arsenite, which is extruded from the cell. A survey of GenBank shows that arsC appears to be phylogenetically widespread both in organisms with known arsenic resistance and those organisms that have been sequenced as part of whole genome projects. Results Phylogenetic analysis of aligned arsC sequences shows broad similarities to the established 16S rRNA phylogeny, with separation of bacterial, archaeal, and subsequently eukaryotic arsC genes. However, inconsistencies between arsC and 16S rRNA are apparent for some taxa. Cyanobacteria and some of the γ-Proteobacteria appear to possess arsC genes that are similar to those of Low GC Gram-positive Bacteria, and other isolated taxa possess arsC genes that would not be expected based on known evolutionary relationships. There is no clear separation of plasmid-borne and chromosomal arsC genes, although a number of the Enterobacteriales (γ-Proteobacteria possess similar plasmid-encoded arsC sequences. Conclusion The overall phylogeny of the arsenate reductases suggests a single, early origin of the arsC gene and subsequent sequence divergence to give the distinct arsC classes that exist today. Discrepancies between 16S rRNA and arsC phylogenies support the role of horizontal gene transfer (HGT in the evolution of arsenate reductases, with a number of instances of HGT early in bacterial arsC evolution. Plasmid-borne arsC genes are not monophyletic suggesting multiple cases of chromosomal-plasmid exchange and subsequent HGT. Overall, arsC phylogeny is complex and is likely the result of a number of evolutionary mechanisms.

  3. A natural analogue for copper waste canisters: The copper-uranium mineralised concretions in the Permian mudrocks of south Devon, United Kingdom

    Energy Technology Data Exchange (ETDEWEB)

    Milodowski, A.E.; Styles, M.T.; Hards, V.L. [Natural Environment Research Council (United Kingdom). British Geological Survey

    2000-08-01

    mineralisation and alteration that can be related to the burial and diagenetic history of the Permian strata. The native copper mineralisation exhibits close temporal association with the formation of uraniferous and vanadiferous concretions (known as 'fish-eyes') in the same rocks. Petrographical relationships indicate that both the copper and the 'fish-eye' concretions formed during burial diagenesis but before the maximum compaction of the host mudstone and siltstone. The regional burial history Wessex Basin, indicates that the maximum compaction of the Permian strata would have been achieved by at least the end of the Lower Jurassic (possibly even in the Triassic). Therefore, the native copper mineralisation is older than 176 Ma. The native copper sheets display a complex sequence of alteration and subsequent mineral growth of minerals on their surfaces. The earliest alteration was to copper oxides - principally cuprite with minor tenorite, indicating a change to more oxidising groundwater conditions. The dissolution of native silver and the growth of fringes of copper arsenides followed this. Nickel arsenides and chalcocite, associated with the precipitation of uranium silicates occurred in the later stages of alteration. This suggests a return to a more reducing pore water environment. Again, petrographical relationships indicate that this alteration and subsequent mineralisation is geologically old (i.e. Lower Jurassic or older). Secondary malachite, intimately intergrown copper sulphate and copper oxides, copper chloride, copper-uranium arsenate and uranium vanadates have formed as late-stage alteration products of the native copper and earlier diagenetic cuprite, chalcocite, copper-nickel arsenide and uranium silicate alteration and mineralisation. This latest stage alteration is most probably attributable to near-surface weathering processes. Although the native copper is affected by corrosion, the study has shown that a significant proportion (30

  4. Arsenite and arsenate removal from wastewater using cationic polymer-modified waste tyre rubber.

    Science.gov (United States)

    Imyim, Apichat; Sirithaweesit, Thitayati; Ruangpornvisuti, Vithaya

    2016-01-15

    Waste tyre rubber (WTR) granulate was modified with a cationic polymer, poly(3-acrylamidopropyl)trimethylammonium chloride (p(APTMACl)). The resulting WTR/p(APTMACl) was utilized for the adsorption of arsenite, As(III) and arsenate, As(V) from aqueous medium in both batch and column methods. The level of adsorption increased gradually with increasing monomer concentration and contact time. The adsorption behavior obeyed the Freundlich model, and the rate of adsorption could be predicted by employing the pseudo-second order model. In the column method, As(V) could be adsorbed onto the sorbent more effectively than As(III). Remarkable desorption of As(III) and As(V) (99 and 92%, respectively) from the adsorbent was achieved using 0.10 M HCl as eluent. An approach of evaluation of adsorption capacity uncertainty is proposed. PMID:26607568

  5. Rubidium titanyl arsenate difference-frequency generation and validation of new Sellmeier coefficients

    Science.gov (United States)

    Fenimore, D. L.; Schepler, K. L.; Zelmon, D.; Kück, S.; Ramabadran, U. B.; von Richter, P.; Small, D.

    1996-09-01

    Rubidium titanyl arsenate (RTA), a crystallographic isomorph of potassium titanyl phosphate, shows promise for nonlinear-frequency generation throughout the 1-5- mu m spectral region. Difference-frequency generation in an RTA crystal produced tunable output in the 3.2-4.2- mu m wavelength range. A single 1.064- mu m Nd:YAG laser pumped both a LiNbO3 optical parametric oscillator used to generate a tunable signal beam and the RTA crystal used for difference-frequency generation. Conversion efficiencies were limited to 4% primarily by the large beam divergence of the signal beam. Phase-matching measurements were in excellent agreement with new IR-corrected RTA Sellmeier equations based on refractive-index measurements. .

  6. Rice-arsenate interactions in hydroponics: a three-gene model for tolerance.

    Science.gov (United States)

    Norton, Gareth J; Nigar, Meher; Williams, Paul N; Dasgupta, Tapash; Meharg, Andrew A; Price, Adam H

    2008-01-01

    In this study, the genetic mapping of the tolerance of root growth to 13.3 muM arsenate [As(V)] using the BalaxAzucena population is improved, and candidate genes for further study are identified. A remarkable three-gene model of tolerance is advanced, which appears to involve epistatic interaction between three major genes, two on chromosome 6 and one on chromosome 10. Any combination of two of these genes inherited from the tolerant parent leads to the plant having tolerance. Lists of potential positional candidate genes are presented. These are then refined using whole genome transcriptomics data and bioinformatics. Physiological evidence is also provided that genes related to phosphate transport are unlikely to be behind the genetic loci conferring tolerance. These results offer testable hypotheses for genes related to As(V) tolerance that might offer strategies for mitigating arsenic (As) accumulation in consumed rice.

  7. Dose dependent changes in 74As-arsenate metabolism of Flemish giant rabbits

    International Nuclear Information System (INIS)

    The metabolic handling of 74As-arsenate (As(V)) was studied in rabbits injected intraperitoneally (i.p) with increasing doses of As(V) (0.00 to 1.00 mgAs(V)/kg/day) over a period of 10 days. Plasma, packed cells, urine from the bladder and several tissues were analyzed for their 74As content and presence of 74As-As(V) metabolites 4 h after administration of 74As-As(V). 74As showed strong increases with increasing As(V) dose in nails and bone whereas in fat, thyroid and kidneys it decreased. Also with increasing As(V) dose, arsenate was less efficiently methylated to dimethylarsenic acid (DMA) and became more bound to insoluble tissue constituents. As a result 74As-DMA levels in tissues were systematically lower in the groups of rabbits receiving the higher doses, be it with a wide variation from one type of tissue to the other. The behaviour of 74As-monomethylarsonic acid (MMA) was different. The levels did not decrease significantly, occasionally even increased compared to the control group, indicating that especially the second methylation step is sensitive towards increasing doses of As(V). 74As-arsenite (As(III)), formed by in vivo reduction of As(V), reached maximal levels in the 0.25 mg As(V)/kg/day group as a result of the inhibited methylation. At doses >0.25 mg As(V)/kg/day the amount of 74As-As(V) increased especially in plasma, packed cells and the urine in the bladder, indicative for a less efficient reduction of As(V). (orig.)

  8. Thiol metabolism and antioxidant systems complement each other during arsenate detoxification in Ceratophyllum demersum L.

    Science.gov (United States)

    Mishra, Seema; Srivastava, Sudhakar; Tripathi, Rudra D; Trivedi, Prabodh K

    2008-01-31

    Ceratophyllum demersum L. is known to be a potential accumulator of arsenic (As), but mechanisms of As detoxification have not been investigated so far. In the present study, we analyzed the biochemical responses of Ceratophyllum plants to arsenate (As(V); 0-250 microM) exposure to explore the underlying mechanisms of As detoxification. Plants efficiently tolerated As toxicity up to concentrations of 50 microM As(V) and durations of 4 d with no significant effect on growth by modulating various pathways in a coordinated and complementary manner and accumulated about 76 microg As g(-1)dw. Significant increases were observed in the levels of various thiols including phytochelatins (PCs), the activities of enzymes of thiolic metabolism as well as arsenate reductase (AR). These primary responses probably enabled plants to detoxify at least some part of As(V) through its reduction and subsequent complexation. The maximum proportion of As chelated by PCs was found to be about 30% (at 50 microM As(V) after 2 d). Simultaneously, a significant increase in the activities of antioxidant enzymes was observed and hence plants did not experience oxidative stress when exposed to 50 microM As(V) for 4 d. Exposure of plants to higher concentrations (250 microM As(V)) and/or for longer durations (7 d) resulted in a significant increase in the level of As (maximum 525 microgg(-1)dw at 250 microM after 7 d) and an inverse relationship between As accumulation and various detoxification strategies was observed that lead to enhanced oxidative stress and hampered growth.

  9. Investigation of biochemical responses of Bacopa monnieri L. upon exposure to arsenate.

    Science.gov (United States)

    Mishra, Seema; Srivastava, Sudhakar; Dwivedi, Sanjay; Tripathi, Rudra Deo

    2013-08-01

    Widespread contamination of arsenic (As) is recognized as a global problem due to its well-known accumulation by edible and medicinal plants and associated health risks for the humans. In this study, phytotoxicity imposed upon exposure to arsenate [As(V); 0-250 μM for 1-7 days] and ensuing biochemical responses were investigated in a medicinal herb Bacopa monnieri L. vis-à-vis As accumulation. Plants accumulated substantial amount of As (total 768 μg g(-1) dw at 250 μM As(V) after 7 days) with the maximum As retention being in roots (60%) followed by stem (23%) and leaves (17%). The level of cysteine and total nonprotein thiols (NP-SH) increased significantly at all exposure concentrations and durations. Besides, the level of metalloid binding ligands viz., glutathione (GSH) and phytochelatins (PCs) increased significantly at the studied concentrations [50 and 250 μM As(V)] in both roots and leaves. The activities of various enzymes viz., arsenate reductase (AR), glutathione reductase (GR), superoxide dismutase (SOD), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), and catalase (CAT) showed differential but coordinated stimulation in leaves and roots to help plants combat As toxicity up to moderate exposure concentrations (50 μM). However, beyond 50 μM, biomass production was found to decrease along with photosynthetic pigments and total soluble proteins, whereas lipid peroxidation increased. In conclusion, As accumulation potential of Bacopa may warrant its use as a phytoremediator but if Bacopa growing in contaminated areas is consumed by humans, it may prove to be toxic for health.

  10. Investigation of biochemical responses of Bacopa monnieri L. upon exposure to arsenate.

    Science.gov (United States)

    Mishra, Seema; Srivastava, Sudhakar; Dwivedi, Sanjay; Tripathi, Rudra Deo

    2013-08-01

    Widespread contamination of arsenic (As) is recognized as a global problem due to its well-known accumulation by edible and medicinal plants and associated health risks for the humans. In this study, phytotoxicity imposed upon exposure to arsenate [As(V); 0-250 μM for 1-7 days] and ensuing biochemical responses were investigated in a medicinal herb Bacopa monnieri L. vis-à-vis As accumulation. Plants accumulated substantial amount of As (total 768 μg g(-1) dw at 250 μM As(V) after 7 days) with the maximum As retention being in roots (60%) followed by stem (23%) and leaves (17%). The level of cysteine and total nonprotein thiols (NP-SH) increased significantly at all exposure concentrations and durations. Besides, the level of metalloid binding ligands viz., glutathione (GSH) and phytochelatins (PCs) increased significantly at the studied concentrations [50 and 250 μM As(V)] in both roots and leaves. The activities of various enzymes viz., arsenate reductase (AR), glutathione reductase (GR), superoxide dismutase (SOD), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), and catalase (CAT) showed differential but coordinated stimulation in leaves and roots to help plants combat As toxicity up to moderate exposure concentrations (50 μM). However, beyond 50 μM, biomass production was found to decrease along with photosynthetic pigments and total soluble proteins, whereas lipid peroxidation increased. In conclusion, As accumulation potential of Bacopa may warrant its use as a phytoremediator but if Bacopa growing in contaminated areas is consumed by humans, it may prove to be toxic for health. PMID:21656644

  11. Arsenate sorption by hydrous ferric oxide incorporated onto granular activated carbon with phenol formaldehyde resins coating.

    Science.gov (United States)

    Zhuang, J M; Hobenshield, E; Walsh, T

    2008-04-01

    A simple and effective method was developed using phenol formaldehyde (PF) resins to immobilize hydrous ferric oxide (HFO) onto granular activated carbon (GAC). The resulting sorbent possesses advantages for both the ferric oxide and the GAC, such as a great As-affinity of ferric oxide, large surface area of GAC, and enhanced physical strength. The studies showed that within one hour this sorbent was able to remove 85% of As(V) from water containing an initial As(V) concentration of 1.74 mg l(-1). The As(V) adsorption onto the sorbent was found to follow a pseudo-second order kinetics model. The adsorption isotherms were interpreted in terms of the Langmuir and Freundlich models. The equilibrium data fitted very well to both models. Column tests showed that this sorbent was able to achieve residual concentrations of As(V) in a range of 0.1-2.0 microg l(-1) while continuously treating about 180 bed volume (BV, 130 ml-BV) of arsenate water with an initial As(V) concentration of 1886 microg l(-1) at a filtration rate of 13.5 ml min(-1), i.e., an empty bed contact time (EBCT) of 9.6 min and a gram sorbent contact time (GSCT) of 0.15 min. After passing 635 BV of arsenate water, the exhausted sorbent was then tested by the Toxicity Characteristic Leaching Procedure (TCLP, US EPA Method 1311) test, and classified as non-hazardous for disposal. Hence, this HFO-PF-coated GAC has the capability to remove As(V) from industrial wastewater containing As(V) levels of about 2 mg l(-1).

  12. Spectral discrimination in color blind animals via chromatic aberration and pupil shape

    Science.gov (United States)

    Stubbs, Alexander L.; Stubbs, Christopher W.

    2016-01-01

    We present a mechanism by which organisms with only a single photoreceptor, which have a monochromatic view of the world, can achieve color discrimination. An off-axis pupil and the principle of chromatic aberration (where different wavelengths come to focus at different distances behind a lens) can combine to provide “color-blind” animals with a way to distinguish colors. As a specific example, we constructed a computer model of the visual system of cephalopods (octopus, squid, and cuttlefish) that have a single unfiltered photoreceptor type. We compute a quantitative image quality budget for this visual system and show how chromatic blurring dominates the visual acuity in these animals in shallow water. We quantitatively show, through numerical simulations, how chromatic aberration can be exploited to obtain spectral information, especially through nonaxial pupils that are characteristic of coleoid cephalopods. We have also assessed the inherent ambiguity between range and color that is a consequence of the chromatic variation of best focus with wavelength. This proposed mechanism is consistent with the extensive suite of visual/behavioral and physiological data that has been obtained from cephalopod studies and offers a possible solution to the apparent paradox of vivid chromatic behaviors in color blind animals. Moreover, this proposed mechanism has potential applicability in organisms with limited photoreceptor complements, such as spiders and dolphins. PMID:27382180

  13. CLASSIFICATION OF COMPLETE 5-PARTITE GRAPHS AND CHROMATICITY OF 5-PARTITE GRAPHSWITH 5n VERTICES

    Institute of Scientific and Technical Information of China (English)

    ZhaoHaixing; LiuRuying; ZhangShenggui

    2004-01-01

    For a graph G,P(G,λ)denotes the chromatic polynomial of G. Two graphs G and H are said to be chromatically equivalent,denoted by G-H,if P(G,λ)=p(H,λ). Let[G]= {H|H-G}. If [G]={G},then G is said to be chromatically unique. For a complete 5-partite graph G with 5n vertices, define θ(G)=(a(G,6)-2n+1-2n-1+5)/2n-2,where a(G,6) denotes the number of 6-independent partitions of G. In this paper, the authors show that θ(G)≥0 and determine all graphs with θ(G)= 0, 1, 2, 5/2, 7/2, 4, 17/4. By using these results the chromaticity of 5-partite graphs of the form G-S with θ(G)=0,1,2,5/2,7/2,4,17/4 is investigated,where S is a set of edges of G. Many new chromatically unique 5-partite graphs are obtained.

  14. An elementary chromatic reduction for gain graphs and special hyperplane arrangements

    CERN Document Server

    Berthome, Pascal; Forge, David; Ventos, Veronique; Zaslavsky, Thomas

    2010-01-01

    A gain graph is a graph whose edges are labelled invertibly by "gains" from a group. "Switching" is a transformation of gain graphs that generalizes conjugation in a group. A "weak chromatic function" of gain graphs with gains in a fixed group satisfies three laws: deletion-contraction for links with neutral gain, invariance under switching, and nullity on graphs with a neutral loop. The laws lead to the "weak chromatic group" of gain graphs, which is the universal domain for weak chromatic functions. We find expressions, valid in that group, for a gain graph in terms of minors without neutral-gain edges, or with added complete neutral-gain subgraphs, that generalize the expression of an ordinary chromatic polynomial in terms of monomials or falling factorials. These expressions imply relations for chromatic functions of gain graphs. We apply our relations to some special integral gain graphs including those that correspond to the Shi, Linial, and Catalan arrangements, thereby obtaining new evaluations of and...

  15. Chromatic-achromatic perimetry in four clinic cases: Glaucoma and diabetes

    Directory of Open Access Journals (Sweden)

    Inmaculada Cabezos

    2015-01-01

    Full Text Available Background: Some diseases that affect the visual system may show loss of chromatic-achromatic sensitivity before obvious physical signs appear in the usual examination of the eye′s posterior segment. A perimetric study has been conducted with four typical patients with glaucoma and diabetes, at different stages of the disease. Materials and Methods: In addition to the standard white-on-white (standard automated perimetry [SAP], a test battery has been used to study patient′s contrast sensitivity, using stimuli with different chromatic, spatial, and temporal content (multichannel perimetry. The choice of stimuli tries to maximize the response of different visual mechanisms: Achromatic (parvocellular and magnocellular origin; chromatic red-green (parvocellular origin; and chromatic blue-yellow (koniocellular origin. Results: The results seem to indicate losses in the achromatic-parvocellular perimetry and both chromatic perimetry tests, undetected by conventional SAP. Conclusions: Our results illustrate that our patients without visible retinal alterations show signs of suspicion in multichannel perimetry.

  16. The distribution of arsenate and arsenite in shoots and roots of Holcus lanatus is influenced by arsenic tolerance and arsenate and phosphate supply.

    Science.gov (United States)

    Quaghebeur, Mieke; Rengel, Zdenko

    2003-07-01

    The recent discovery that phytochelatins are important for arsenic (As) detoxification in terrestrial plants results in the necessity to understand As speciation and metabolism in plant material. A hydroponic study was therefore conducted to examine the effects of different levels of phosphate and arsenate [As(V)] on As speciation and distribution in tolerant and non-tolerant clones of Holcus lanatus. Speciation of As in tissue (using high-performance liquid chromatography-inductively coupled plasma mass spectrometry) revealed that the predominant species present were the inorganic As species (As(V) and arsenite [As(III)]), although small levels (<1%) of organic As species (dimethylarsinic acid and monomethylarsonic acid) were detected in shoot material. In roots, the proportion of total As present as As(III) generally increased with increasing levels of As(V) in the nutrient solution, whereas in shoots, the proportion of total As present as As(III) generally decreased with increasing levels of As(V). H. lanatus plants growing in the high-phosphorus (P) (100 micro M) solution contained a higher proportion of As(V) (with regard to total As) in both roots and shoots than plants supplied with low P (10 micro M); in addition, tolerant clones generally contained a higher proportion of As(V) with regard to total As than non-tolerant clones. The study further revealed that As(V) can be reduced to As(III) in both roots and shoots. Although the reduction capacity was limited, the reduction was closely regulated by As influx for all treatments. The results therefore provide a new understanding about As metabolism in H. lanatus.

  17. Characteristics of copper meshes coated with carbon nanotubes via electrophoretic deposition

    Science.gov (United States)

    Kim, Bu-Jong; Park, Jong-Seol; Hwang, Young-Jin; Park, Jin-Seok

    2016-09-01

    This study demonstrates the characteristics of a hybrid-type transparent electrode for touch screen panels, which was fabricated by coating carbon nanotubes (CNTs) via electrophoretic deposition (EPD) on copper (Cu)-meshes. The surface morphologies, visible-range transmittance and reflectance, and chromatic properties, such as yellowness and redness, of the fabricated CNTs-coated Cu mesh electrodes were characterized as functions of their dimensions (line-to-line spacing, line width, and electrode thickness) and compared with those of the Cu-mesh electrodes without coating of CNTs. The experimental results showed that the coating of CNTs substantially reduced the reflectance of the Cu-mesh electrodes and also improved their chromatic properties with their transmittance and sheet resistance only slightly changed, subsequently indicating that the CNTs-coated Cu-mesh electrodes possessed desirable characteristics for touch screen panels.

  18. Development of a thermodynamic data base for selected heavy metals

    International Nuclear Information System (INIS)

    The report on the development of a thermodynamic data base for selected heavy metals covers the description of experimental methods, the thermodynamic model for chromate, the thermodynamic model for dichromate, the thermodynamic model for manganese (II), the thermodynamic model for cobalt, the thermodynamic model for nickel, the thermodynamic model for copper (I), the thermodynamic model for copper(II), the thermodynamic model for mercury (0) and mercury (I), the thermodynamic model for mercury (III), the thermodynamic model for arsenate.

  19. Development of a thermodynamic data base for selected heavy metals; Entwicklung einer thermodynamischen Datenbasis fuer ausgewaehlte Schwermetalle

    Energy Technology Data Exchange (ETDEWEB)

    Hageman, Sven; Scharge, Tina; Willms, Thomas

    2015-07-15

    The report on the development of a thermodynamic data base for selected heavy metals covers the description of experimental methods, the thermodynamic model for chromate, the thermodynamic model for dichromate, the thermodynamic model for manganese (II), the thermodynamic model for cobalt, the thermodynamic model for nickel, the thermodynamic model for copper (I), the thermodynamic model for copper(II), the thermodynamic model for mercury (0) and mercury (I), the thermodynamic model for mercury (III), the thermodynamic model for arsenate.

  20. Limits on Foreground Subtraction from Chromatic Beam Effects in Global Redshifted 21 cm Measurements

    CERN Document Server

    Mozdzen, Thomas J; Monsalve, Raul A; Rogers, Alan E E

    2015-01-01

    Foreground subtraction in global redshifted 21 cm measurements is limited by frequency-dependent (chromatic) structure in antenna beam patterns. Chromatic beams couple angular structures in Galactic foreground emission to spectral structures that may not be removed by smooth functional forms. We report results for simulations based on two dipole antennas used by the Experiment to Detect the Global EoR Signature (EDGES). The residual levels in simulated foreground-subtracted spectra are found to differ substantially between the two antennas, suggesting that antenna design must be carefully considered. Residuals are also highly dependent on the right ascension and declination of the antenna pointing, with RMS values differing by as much as a factor of 20 across pointings. For EDGES and other ground-based experiments with zenith pointing antennas, right ascension and declination correspond directly to the local sidereal time and the latitude of the deployment site, hence chromatic beam effects should be taken in...

  1. REMOVAL OF CHROMATE ION FROM CONTAMINATED SYNTHETIC WATER USING MCM-41/ZSM-5 COMPOSITE

    Directory of Open Access Journals (Sweden)

    H. Kazemian, M. H. Mallah

    2008-01-01

    Full Text Available In the present study removal of chromate anion (CrO42- from a synthetic aqueous solution by a synthesized MCM-41/ZSM-5 composite and its modified form with the anionic surfactant of hexadecyl-teri methyl ammonium bromide; (surfactant modified composite was investigated. According to the data obtained from batch test of MCM-41/ZSM-5 composite and surfactant modified composite, it is obvious that modification of the composite with anionic surfactant improves its affinity toward the oxyanion (917mL/g for MCM-41/ZSM-5 composite in comparison to 1870mL/g for surfactant modified composite. It was concluded that sorption capacity and selectivity of the composite will be remarkly improve toward chromate anion by modification of its surface by a surfactant; therefore surfactant modified composite is a suitable candidate for removal of chromate anion from contaminated solutions.

  2. Tune and Chromaticity Control During Snapback and Ramp in 2015 LHC Operation

    CERN Document Server

    Schaumann, Michaela; Lamont, Mike; Solfaroli Camillocci, Matteo; Todesco, Ezio; Wenninger, Jorg

    2016-01-01

    Because of current redistribution on the superconducting cables, the harmonic components of the magnetic fields of the superconducting magnets in the Large Hadron Collider (LHC) show decay during the low field injection plateau. This results in tune and chromaticity variations for the beams. In the first few seconds of the ramp the original hysteresis state of the magnetic field is restored - the field snaps back. These fast dynamic field changes lead to strong tune and chromaticity excursions that, if not properly controlled, induce beam losses and potentially trigger a beam dump. A feed-forward system applies predicted corrections during the injection plateau and to the first part of the ramp to avoid violent changes of beam conditions. This paper discusses the snapback of tune and chromaticity as observed in 2015, as well as the control of beam parameters during the ramp. It also evaluates the quality of the applied feed-forward corrections and their reproducibility.

  3. Molybdate based Alternatives to Chromating as a Passivation Treatment for Zinc

    DEFF Research Database (Denmark)

    Tang, Peter Torben; Bech-Nielsen, G.; Møller, Per

    1994-01-01

    Zinc-plated parts are typically passivated with chromate-based solutions to reduce corrosion. Chromates, however, are a cause of environmental concern, for their toxic effects on plants and wildlife, and allergic effects on workers who come in contact with them. A molybdate-based alternative has...... been developed that can be used to replace chromates in a wide range of applications. The process has been tested in a project set up by the Danish Government in 1989, at the Centre of Advanced Electroplating (CAG)in Denmark. Procedures used for the alternative process are similar to those used...... tests, but not as good in neutral tests, such as salt spray. This edited version of a presentation from the joint AESF/EAST Session at SUR/FIN(R) '94-Indianapolis, discusses the effectiveness, cost, stability, chemistry, layer composition, and performance of this alternative process....

  4. Versatile chromatic dispersion measurement of a single mode fiber using spectral white light interferometry.

    Science.gov (United States)

    Lee, Ji Yong; Kim, Dug Young

    2006-11-27

    We present a versatile and accurate chromatic dispersion measurement method for single mode optical fibers over a wide spectral range (200 nm) using a spectral domain white light interferometer. This technique is based on spectral interferometry with a Mach-Zehnder interferometer setup and a broad band light source. It takes less than a second to obtain a spectral interferogram for a few tens of centimeter length fiber sample. We have demonstrated that the relative group velocity, the chromatic dispersion and the dispersion slope of a sample fiber can be obtained very accurately regardless of the zero-dispersion wavelength (ZDW) of a sample after frequency dependent optical phase was directly retrieved from a spectral interferogram. The measured results with our proposed method were compared with those obtained with a conventional time-domain dispersion measurement method. A good agreement between those results indicates that our proposed method can measure the chromatic dispersion of a short length optical fiber with very high accuracy.

  5. Structure determination and functional analysis of a chromate reductase from Gluconacetobacter hansenii.

    Directory of Open Access Journals (Sweden)

    Hongjun Jin

    Full Text Available Environmental protection through biological mechanisms that aid in the reductive immobilization of toxic metals (e.g., chromate and uranyl has been identified to involve specific NADH-dependent flavoproteins that promote cell viability. To understand the enzyme mechanisms responsible for metal reduction, the enzyme kinetics of a putative chromate reductase from Gluconacetobacter hansenii (Gh-ChrR was measured and the crystal structure of the protein determined at 2.25 Å resolution. Gh-ChrR catalyzes the NADH-dependent reduction of chromate, ferricyanide, and uranyl anions under aerobic conditions. Kinetic measurements indicate that NADH acts as a substrate inhibitor; catalysis requires chromate binding prior to NADH association. The crystal structure of Gh-ChrR shows the protein is a homotetramer with one bound flavin mononucleotide (FMN per subunit. A bound anion is visualized proximal to the FMN at the interface between adjacent subunits within a cationic pocket, which is positioned at an optimal distance for hydride transfer. Site-directed substitutions of residues proposed to involve in both NADH and metal anion binding (N85A or R101A result in 90-95% reductions in enzyme efficiencies for NADH-dependent chromate reduction. In comparison site-directed substitution of a residue (S118A participating in the coordination of FMN in the active site results in only modest (50% reductions in catalytic efficiencies, consistent with the presence of a multitude of side chains that position the FMN in the active site. The proposed proximity relationships between metal anion binding site and enzyme cofactors is discussed in terms of rational design principles for the use of enzymes in chromate and uranyl bioremediation.

  6. Structure Determination and Functional Analysis of a Chromate Reductase from Gluconacetobacter hansenii

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Hongjun; Zhang, Yanfeng; Buchko, Garry W.; Varnum, Susan M.; Robinson, Howard; Squier, Thomas C.; Long, Philip E.

    2012-08-06

    Environmental protection through biological mechanisms that aid in the reductive immobilization of toxic metals (e.g.,chromate and uranyl) has been identified to involve specific NADH-dependent flavoproteins that promote cell viability. To understand the enzyme mechanisms responsible for metal reduction, the enzyme kinetics of a putative chromate reductasefrom Gluconacetobacter hansenii (Gh-ChrR) was measured and the crystal structure of the protein determined at 2.25 A°resolution. Gh-ChrR catalyzes the NADH-dependent reduction of chromate, ferricyanide, and uranyl anions under aerobic conditions. Kinetic measurements indicate that NADH acts as a substrate inhibitor; catalysis requires chromate binding prior to NADH association. The crystal structure of Gh-ChrR shows the protein is a homotetramer with one bound flavin mononucleotide (FMN) per subunit. A bound anion is visualized proximal to the FMN at the interface between adjacentsubunits within a cationic pocket, which is positioned at an optimal distance for hydride transfer. Site-directed substitutions of residues proposed to involve in both NADH and metal anion binding (N85A or R101A) result in 90–95% reductions in enzyme efficiencies for NADH-dependent chromate reduction. In comparison site-directed substitution of a residue (S118A) participating in the coordination of FMN in the active site results in only modest (50%) reductions in catalytic efficiencies, consistent with the presence of a multitude of side chains that position the FMN in the active site. The proposed proximity relationships between metal anion binding site and enzyme cofactors is discussed in terms of rational design principles for the use of enzymes in chromate and uranyl bioremediation.

  7. On Chromatic no. of 3K1-free graphs and R(3, k)

    OpenAIRE

    Dhurandhar, Medha S.

    2012-01-01

    Here we prove that if G has independence no. 2 and clique size omega with omega less than or equal to 11, then (1) chromatic no. is less than or equal to (omega2+12omega-13)/8, if omega is odd, and (2) chromatic no. is less than or equal to (omega2+10omega)/8, if omega is even. We further conjecture that the results are true in general for all omega. We also conjecture that (A) if omega is odd and R(3, omega) is even, then R(3, omega) = (omega2+8omega-9)/4, (B) if omega and R(3, omega) are bo...

  8. Longitudinal measurement of chromatic dispersion along an optical fiber transmission system with a new correction factor

    International Nuclear Information System (INIS)

    At present existence OTDR based techniques have become a standard practice for measuring chromatic dispersion distribution along an optical fiber transmission link. A constructive measurement technique has been offered in this paper, in which a four wavelength bidirectional optical time domain reflectometer (OTDR) has been used to compute the chromatic dispersion allocation beside an optical fiber transmission system. To improve the correction factor a novel formulation has been developed, which leads to an enhanced and defined measurement. The investigational outcomes obtained are in good harmony

  9. Spatial Light Modulator Based on Surface Plasmon Polaritons for Chromatic Display

    Institute of Scientific and Technical Information of China (English)

    WANG Jing-Quan; HUANG Feng; DU Jing-Lei; GUO Yong-Kang; LUO Xian-Gang; DU Chun-Lei

    2008-01-01

    @@ A spatial light modulator (SLM) based on surface plasmon polaritons (SPPs) that can generate chromatic pattern is demonstrated. The device is composed of a waveguide with a thin silver film and an active material The simulated results show that the SLM can modulate the intensity of three different wavelengths at the same time and combine a colour picture in the image surface. The SLM also owns the characteristics of high sensitivity, high contrast, fast time response etc. This means that the SLM is promising in the chromatic display.

  10. Rare earth and silane as chromate replacers for corrosion protection on galvanized steel

    Institute of Scientific and Technical Information of China (English)

    PENG Tianlan; MAN Ruilin

    2009-01-01

    The present work aimed at using rare earth lanthanum salt and trimethoxy(viny)silance as chromate substitutes for galvanized steel passivation, in contrast to zinc coating samples treated with chromate. The corrosion resistance was assessed by electrochemical impedance spectroscopy (EIS) and neutral salt spray tests (NSS). Scanning electron microscopy (SEM) was used to characterize the sample surfaces. The organic coating adhesion on the panel was also investigated via varnishes-cross cut tests. The results indicated that rare earth and silane two-step treatment gave more effective anticorrosion performance than Cr, which also provided good paint adhesion. The coating formation mechanism was also discussed.

  11. New chromaticity compensation approach and dynamic aperture increase in the SSRF storage ring

    Institute of Scientific and Technical Information of China (English)

    TIAN Shun-Qiang; HOU Jie; CHEN Guang-Ling; LIU Gui-Min

    2008-01-01

    Strong chromatic sextupoles used to compensate natural chromaticities in the third generation light source storage ring usually reduce dynamic aperture drastically.Many optimization methods can be used to find solutions that provide large dynamic apertures.This paper discusses a new optimization approach of sextupole strengths with step-by-step procedure,which is applied in the SSRF storage ring,and a better solution is obtained.Investigating driving terms generated by the sextupoles in every step can analyze their convergences and guide the weight setting among different terms in object function of the single resonance approach based on the perturbation theory.

  12. The removal of sulphate from mine water by precipitation as ettringite and the utilisation of the precipitate as a sorbent for arsenate removal.

    Science.gov (United States)

    Tolonen, Emma-Tuulia; Hu, Tao; Rämö, Jaakko; Lassi, Ulla

    2016-10-01

    The aim of this research was to investigate sulphate removal from mine water by precipitation as ettringite (Ca6Al2(SO4)3(OH)12·26H2O) and the utilisation of the precipitate as a sorbent for arsenate removal. The mine water sulphate concentration was reduced by 85-90% from the initial 1400 mg/L during ettringite precipitation depending on the treatment method. The precipitation conditions were also simulated with MINEQL + software, and the computational results were compared with the experimental results. The precipitated solids were characterised with X-ray diffraction and a scanning electron microscope. The precipitated solids were tested as sorbents for arsenate removal from the model solution. The arsenic(V) model solution concentration reduced 86-96% from the initial 1.5 mg/L with a 1 g/L sorbent dosage. The effect of initial arsenate concentration on the sorption of arsenate on the precipitate was studied and Langmuir, Freundlich, and Langmuir-Freundlich sorption isotherm models were fitted to the experimental data. The maximum arsenate sorption capacity (qm = 11.2 ± 4.7 mg/g) of the precipitate was obtained from the Langmuir-Freundlich isotherm. The results indicate that the precipitate produced during sulphate removal from mine water by precipitation as ettringite could be further used as a sorbent for arsenate removal.

  13. Copper Bioleaching in Chile

    OpenAIRE

    Juan Carlos Gentina; Fernando Acevedo

    2016-01-01

    Chile has a great tradition of producing and exporting copper. Over the last several decades, it has become the first producer on an international level. Its copper reserves are also the most important on the planet. However, after years of mineral exploitation, the ease of extracting copper oxides and ore copper content has diminished. To keep the production level high, the introduction of new technologies has become necessary. One that has been successful is bioleaching. Chile had the first...

  14. Copper-tantalum alloy

    Science.gov (United States)

    Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

    1986-07-15

    A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

  15. Copper Metabolism of Astrocytes

    Directory of Open Access Journals (Sweden)

    Ralf eDringen

    2013-03-01

    Full Text Available This short review will summarize the current knowledge on the uptake, storage and export of copper ions by astrocytes and will address the potential roles of astrocytes in copper homeostasis in the normal and diseased brain. Astrocytes in culture efficiently accumulate copper by processes that include both the copper transporter Ctr1 and Ctr1-independent mechanisms. Exposure of astrocytes to copper induces an increase in cellular glutathione (GSH content as well as synthesis of metallothioneins, suggesting that excess of copper is stored as complex with GSH and in metallothioneins. Furthermore, exposure of astrocytes to copper accelerates the release of GSH and of glycolytically generated lactate. Astrocytes are able to export copper and express the Menkes protein ATP7A. This protein undergoes reversible, copper-dependent trafficking between the trans-Golgi network and vesicular structures. The ability of astrocytes to efficiently take up, store and export copper suggests that astrocytes play a key role in the supply of neurons with copper and that astrocytes should be considered as target for therapeutic inventions that aim to correct disturbances in brain copper homeostasis.

  16. [Copper pathology (author's transl)].

    Science.gov (United States)

    Mallet, B; Romette, J; Di Costanzo, J D

    1982-01-30

    Copper is an essential dietary component, being the coenzyme of many enzymes with oxidase activity, e.g. ceruloplasmin, superoxide dismutase, monoamine oxidase, etc. The metabolism of copper is complex and imperfectly known. Active transport of copper through the intestinal epithelial cells involves metallothionein, a protein rich in sulfhydryl groups which also binds the copper in excess and probably prevents absorption in toxic amounts. In hepatocytes a metallothionein facilitates absorption by a similar mechanism and regulates copper distribution in the liver: incorporation in an apoceruloplasmin, storage and synthesis of copper-dependent enzymes. Metallothioneins and ceruloplasmin are essential to adequate copper homeostasis. Apart from genetic disorders, diseases involving copper usually result from hypercupraemia of varied origin. Wilson's disease and Menkes' disease, although clinically and pathogenetically different, are both marked by low ceruloplasmin and copper serum levels. The excessive liver retention of copper in Wilson's disease might be due to increased avidity of hepatic metallothioneins for copper and decreased biliary excretion through lysosomal dysfunction. Menkes' disease might be due to low avidity of intestinal and hepatic metallothioneins for copper. The basic biochemical defect responsible for these two hereditary conditions has not yet been fully elucidated.

  17. Enzyme phylogenies as markers for the oxidation state of the environment: The case of respiratory arsenate reductase and related enzymes

    Directory of Open Access Journals (Sweden)

    Schoepp-Cothenet Barbara

    2008-07-01

    Full Text Available Abstract Background Phylogenies of certain bioenergetic enzymes have proved to be useful tools for deducing evolutionary ancestry of bioenergetic pathways and their relationship to geochemical parameters of the environment. Our previous phylogenetic analysis of arsenite oxidase, the molybdopterin enzyme responsible for the biological oxidation of arsenite to arsenate, indicated its probable emergence prior to the Archaea/Bacteria split more than 3 billion years ago, in line with the geochemical fact that arsenite was present in biological habitats on the early Earth. Respiratory arsenate reductase (Arr, another molybdopterin enzyme involved in microbial arsenic metabolism, serves as terminal oxidase, and is thus situated at the opposite end of bioenergetic electron transfer chains as compared to arsenite oxidase. The evolutionary history of the Arr-enzyme has not been studied in detail so far. Results We performed a genomic search of genes related to arrA coding for the molybdopterin subunit. The multiple alignment of the retrieved sequences served to reconstruct a neighbor-joining phylogeny of Arr and closely related enzymes. Our analysis confirmed the previously proposed proximity of Arr to the cluster of polysulfide/thiosulfate reductases but also unravels a hitherto unrecognized clade even more closely related to Arr. The obtained phylogeny strongly suggests that Arr originated after the Bacteria/Archaea divergence in the domain Bacteria, and was subsequently laterally distributed within this domain. It further more indicates that, as a result of accumulation of arsenate in the environment, an enzyme related to polysulfide reductase and not to arsenite oxidase has evolved into Arr. Conclusion These findings are paleogeochemically rationalized by the fact that the accumulation of arsenate over arsenite required the increase in oxidation state of the environment brought about by oxygenic photosynthesis.

  18. Different arsenate and phosphate incorporation effects on the nucleation and growth of iron(III) (Hydr)oxides on quartz.

    Science.gov (United States)

    Neil, Chelsea W; Lee, Byeongdu; Jun, Young-Shin

    2014-10-21

    Iron(III) (hydr)oxides play an important role in the geochemical cycling of contaminants in natural and engineered aquatic systems. The ability of iron(III) (hydr)oxides to immobilize contaminants can be related to whether the precipitates form heterogeneously (e.g., at mineral surfaces) or homogeneously in solution. Utilizing grazing incidence small-angle X-ray scattering (GISAXS), we studied heterogeneous iron(III) (hydr)oxide nucleation and growth on quartz substrates for systems containing arsenate and phosphate anions. For the iron(III) only system, the radius of gyration (Rg) of heterogeneously formed precipitates grew from 1.5 to 2.5 (± 1.0) nm within 1 h. For the system containing 10(-5) M arsenate, Rg grew from 3.6 to 6.1 (± 0.5) nm, and for the system containing 10(-5) M phosphate, Rg grew from 2.0 to 4.0 (± 0.2) nm. While the systems containing these oxyanions had more growth, the system containing only iron(III) had the most nucleation events on substrates. Ex situ analyses of homogeneously and heterogeneously formed precipitates indicated that precipitates in the arsenate system had the highest water content and that oxyanions may bridge iron(III) hydroxide polymeric embryos to form a structure similar to ferric arsenate or ferric phosphate. These new findings are important because differences in nucleation and growth rates and particle sizes will impact the number of available reactive sites and the reactivity of newly formed particles toward aqueous contaminants.

  19. The oxygen isotope composition of dissolved chromate: a new tool for determining sources of chromium contamination in groundwater

    Science.gov (United States)

    Bullen, T.; Widory, D.

    2009-05-01

    Hexavalent chromium (Cr(VI)) is a widespread carcinogen in groundwater, derived from both anthropogenic and natural sources. A large range of chromium isotope composition has been demonstrated for dissolved Cr(VI) in groundwater, resulting from the large isotope fractionation accompanying reduction of Cr(VI) to trivalent chromium (Cr(III)). As a result, the isotopic composition of chromium in dissolved chromate is beginning to prove useful for determining the sources of chromium in contaminated groundwater, but considered alone can likewise be non-diagnostic due to overlapping compositional ranges of potential anthropogenic and natural sources. Based on the strong Cr-O bond in the chromate molecule implied by the large chromium isotope fractionation accompanying Cr(VI) reduction, we have proposed that oxygen will remain closely linked to chromium in the chromate molecule and thus can be used to better constrain chromate sources through a Cr-O "multi-tracer" approach. In a series of laboratory experiments using isotopically "enriched" water and "normal" chromate, we have demonstrated that there is insignificant isotopic exchange between oxygen in chromate and water for residence times as long as one year, and thus chromate will retain the oxygen isotope composition of its source during extended transport in groundwater. We have likewise demonstrated that sufficient chromate for oxygen isotope analysis can be successfully isolated from a chemically complex groundwater sample through a series of precipitation, ion exchange and heating procedures. Although our current approach of measuring 100 micromolar samples of chromate using TCEA- gas mass spectrometry is straightforward and robust, we are also developing a negative-ion thermal ionization mass spectrometry technique in order to greatly reduce the sample size requirement. We are currently applying this novel technique at an electric power facility in California and a metal plating facility in France in order to

  20. The removal of arsenate from water using iron-modified diatomite (D-Fe): isotherm and column experiments.

    Science.gov (United States)

    Pantoja, M L; Jones, H; Garelick, H; Mohamedbakr, H G; Burkitbayev, M

    2014-01-01

    Iron hydroxide supported onto porous diatomite (D-Fe) is a low-cost material with potential to remove arsenic from contaminated water due to its affinity for the arsenate ion. This affinity was tested under varying conditions of pH, contact time, iron content in D-Fe and the presence of competitive ions, silicate and phosphate. Batch and column experiments were conducted to derive adsorption isotherms and breakthrough behaviours (50 μg L(-1)) for an initial concentration of 1,000 μg L(-1). Maximum capacity at pH 4 and 17% iron was 18.12-40.82 mg of arsenic/g of D-Fe and at pH 4 and 10% iron was 18.48-29.07 mg of arsenic/g of D-Fe. Adsorption decreased in the presence of phosphate and silicate ions. The difference in column adsorption behaviour between 10% and 17% iron was very pronounced, outweighing the impact of all other measured parameters. There was insufficient evidence of a correlation between iron content and arsenic content in isotherm experiments, suggesting that ion exchange is a negligible process occurring in arsenate adsorption using D-Fe nor is there co-precipitation of arsenate by rising iron content of the solute above saturation.

  1. Arsenate tolerance mechanism of Oenothera odorata from a mine population involves the induction of phytochelatins in roots.

    Science.gov (United States)

    Kim, Dae-Yeon; Park, Hyun; Lee, Sang-Hwan; Koo, Namin; Kim, Jeong-Gyu

    2009-04-01

    We investigated the arsenate tolerance mechanisms of Oenothera odorata by comparing two populations [i.e., one population from the mine site (MP) and the other population from an uncontaminated site (UP)] via the exposure of hydroponic solution containing arsenate (i.e., 0-50 microM). The MP plants were significantly more tolerant to arsenate than UP plants. The UP plants accumulated more As in their shoots and roots than did the MP plants. The UP plants translocated up to 21 microg g(-1) of As into shoots, whereas MP plants translocated less As (up to 4.5 microg g(-1)) to shoots over all treatments. The results of lipid peroxidation indicated that MP plants were less damaged by oxidative stress than were UP plants. Phytochelatin (PC) content correlated linearly with root As concentration in the MP (i.e., [PCs](root)=1.69x[As](root), r(2)=0.945) and UP (i.e., [PCs](root)=0.89x[As](root), r(2)=0.979) plants. This relationship means that increased PC to As ratio may be associated with increased tolerance. Our results suggest that PC induction in roots plays a critical role in As tolerance of O. odorata.

  2. Surface chemistry of ferrihydrite: Part 2. Kinetics of arsenate adsorption and coprecipitation

    Science.gov (United States)

    Fuller, C.C.; Dadis, J.A.; Waychunas, G.A.

    1993-01-01

    The kinetics of As(V) adsorption by ferrihydrite was investigated in coprecipitation and postsynthesis adsorption experiments conducted in the pH range 7.5-9.0. In coprecipitation experiments, As(V) was present in solution during the hydrolysis and precipitation of iron. In adsorption experiments, a period of rapid (adsorption sites on ferrihydrite surfaces within aggregates of colloidal particles. The time dependence of As(V) adsorption is well described by a general model for diffusion into a sphere if a subset of surface sites located near the exterior of aggregates is assumed to attain adsorptive equilibrium rapidly. The kinetics of As(V) desorption after an increase in pH were also consistent with diffusion as a rate-limiting process. Aging of pure ferrihydrite prior to As(V) adsorption caused a decrease in adsorption sites on the precipitate owing to crystallite growth. In coprecipitation experiments, the initial As(V) uptake was significantly greater than in post-synthesis adsorption experiments, and the rate of uptake was not diffusion limited because As(V) was coordinated by surface sites before crystallite growth and coagulation processes could proceed. After the initial adsorption, As(V) was slowly released from coprecipitates for at least one month, as crystallite growth caused desorption of As(V). Adsorption densities as high as 0.7 mole As(V) per mole of Fe were measured in coprecipitates, in comparison to 0.25 mole As(V) per mole of Fe in post-synthesis adsorption experiments. Despite the high Concentration of As(V) in the precipitates, EXAFS spectroscopy (Waychunas et al., 1993) showed that neither ferric arsenate nor any other As-bearing surface precipitate or solid solution was formed. The high adsorption densities are possible because the ferrihydrite particles are extremely small, approaching the size of small dioctahedral chains at the highest As(V) adsorption density. The results suggest that the solid solution model proposed by Fox (1989

  3. Copper Bioleaching in Chile

    Directory of Open Access Journals (Sweden)

    Juan Carlos Gentina

    2016-03-01

    Full Text Available Chile has a great tradition of producing and exporting copper. Over the last several decades, it has become the first producer on an international level. Its copper reserves are also the most important on the planet. However, after years of mineral exploitation, the ease of extracting copper oxides and ore copper content has diminished. To keep the production level high, the introduction of new technologies has become necessary. One that has been successful is bioleaching. Chile had the first commercial operation in the world exclusively via bioleaching copper sulfides. Nowadays, all bioleaching operations run in the country contribute to an estimated 10% of total copper production. This article presents antecedents that have contributed to the development of copper bioleaching in Chile.

  4. Accurate chromatic control and color rendering optimization in LED lighting systems using junction temperature feedback

    Science.gov (United States)

    Sisto, Marco Michele; Gauvin, Jonny

    2014-09-01

    Accurate color control of LED lighting systems is a challenging task: noticeable chromaticity shifts are commonly observed in mixed-color and phosphor converted LEDs due to intensity dimming. Furthermore, the emitted color varies with the LED temperature. We present a novel color control method for tri-chromatic and tetra-chromatic LEDs, which enable to set and maintain the LED emission at a target color, or combination of correlated color temperature (CCT) and intensity. The LED color point is maintained over variations in the LED junctions' temperatures and intensity dimming levels. The method does not require color feedback sensors, so to minimize system complexity and cost, but relies on estimation of the LED junctions' temperatures from the junction voltages. If operated with tetra-chromatic LEDs, the method allows meeting an additional optimization criterion: for example, the maximization of a color rendering metric like the Color Rendering Index (CRI) or the Color Quality Scale (CQS), thus providing a high quality and clarity of colors on the surface illuminated by the LED. We demonstrate the control of a RGBW LED at target D65 white point with CIELAB color difference metric triangle;a,bE temperature from 25°C to 58°C. In the same conditions, we demonstrate a CCT error <1%. Furthermore, the method allows varying the LED CCT from 5500K to 8000K while maintaining luminance within 1% of target. Further work is ongoing to evaluate the stability of the method over LED aging.

  5. Segmentation of color images by chromaticity features using self-organizing maps

    Directory of Open Access Journals (Sweden)

    Farid García-Lamont

    2016-08-01

    Full Text Available Usually, the segmentation of color images is performed using cluster-based methods and the RGB space to represent the colors. The drawback with these methods is the a priori knowledge of the number of groups, or colors, in the image; besides, the RGB space issensitive to the intensity of the colors. Humans can identify different sections within a scene by the chromaticity of its colors of, as this is the feature humans employ to tell them apart. In this paper, we propose to emulate the human perception of color by training a self-organizing map (SOM with samples of chromaticity of different colors. The image to process is mapped to the HSV space because in this space the chromaticity is decoupled from the intensity, while in the RGB space this is not possible. Our proposal does not require knowing a priori the number of colors within a scene, and non-uniform illumination does not significantly affect the image segmentation. We present experimental results using some images from the Berkeley segmentation database by employing SOMs with different sizes, which are segmented successfully using only chromaticity features.

  6. Commissioning of the nonlinear chromaticity at injection for LHC Run II

    CERN Document Server

    AUTHOR|(CDS)2080608; Tomas Garcia, Rogelio; Carlier, Felix Simon; Langner, Andy Sven; Malina, Lukas; Persson, Tobias Hakan Bjorn; Coello De Portugal - Martinez Vazquez, Jaime Maria; Skowronski, Piotr Krzysztof; Garcia-Tabares Valdivieso, Ana; CERN. Geneva. ATS Department

    2016-01-01

    For the first time, correction of nonlinear chromaticity and amplitude detuning was included in the LHC commissioning for Run II. The corrections found during the nonlinear optics commissioning have been deployed operationally at injection in the LHC. This note summarizes the relevant measurements and corrections performed during the first commissioning of the LHC in Run II

  7. Orbit, optics and chromaticity correction for PS2 negative momentum compaction lattices

    Energy Technology Data Exchange (ETDEWEB)

    Papaphilippou,Y.; Barranco, J.; Bartmann, W.; Benedikt, M.; Carli, C.; de Maria, R.; Peggs, S.; Trbojevic, D.

    2009-05-04

    The effect of magnet misalignments in the beam orbit and linear optics functions are reviewed and correction schemes are applied to the negative momentum compaction lattice of PS2. Chromaticity correction schemes are also proposed and tested with respect to off-momentum optics properties. The impact of the correction schemes in the dynamic aperture of the lattice is finally evaluated.

  8. Perception of Chromatic cues during host location by the pupal parasitoid Pimpla turionellae (L.) (Hymenoptera: Ichneumonidae)

    NARCIS (Netherlands)

    Fischer, S.; Samietz, J.; Wäckers, F.L.; Dorn, S.

    2004-01-01

    Chromatic and achromatic plant cues are expected to be particularly important for parasitoids of endophytic pupal hosts, because these stages do not feed and therefore avoid volatile emission caused by plant tissue damage. Endophytic feeding can cause discoloration or desiccation, leading to changes

  9. Spatial and temporal aspects of chromatic adaptation and their functional significance for colour constancy.

    Science.gov (United States)

    Werner, Annette

    2014-11-01

    Illumination in natural scenes changes at multiple temporal and spatial scales: slow changes in global illumination occur in the course of a day, and we encounter fast and localised illumination changes when visually exploring the non-uniform light field of three-dimensional scenes; in addition, very long-term chromatic variations may come from the environment, like for example seasonal changes. In this context, I consider the temporal and spatial properties of chromatic adaptation and discuss their functional significance for colour constancy in three-dimensional scenes. A process of fast spatial tuning in chromatic adaptation is proposed as a possible sensory mechanism for linking colour constancy to the spatial structure of a scene. The observed middlewavelength selectivity of this process is particularly suitable for adaptation to the mean chromaticity and the compensation of interreflections in natural scenes. Two types of sensory colour constancy are distinguished, based on the functional differences of their temporal and spatial scales: a slow type, operating at a global scale for the compensation of the ambient illumination; and a fast colour constancy, which is locally restricted and well suited to compensate region-specific variations in the light field of three dimensional scenes. PMID:25449338

  10. On the chromatic number of pentagon-free graphs of large minimum degree

    DEFF Research Database (Denmark)

    Thomassen, Carsten

    2007-01-01

    We prove that, for each fixed real number c > 0, the pentagon-free graphs of minimum degree at least cn (where n is the number of vertices) have bounded chromatic number. This problem was raised by Erdős and Simonovits in 1973. A similar result holds for any other fixed odd cycle, except the tria...

  11. SIMULTANEOUS DTERMINATION OF CHROMATE AND AROMATIC HYDROCARBONS IN ENVIRONMENTAL SAMPLES BY CAPILLARY ELECTROPHORESIS

    Science.gov (United States)

    An analytical method was developed to determine simultaneously, the inorganic anion CrO2-4, and organic aromatic compounds including benzoate, 2-Cl-benzoate, phenol, m-cresol and o-/p-cresol by capillary electrophoresis (CE). Chromate and the aromatics were separated in a relativ...

  12. Experimental verification of the minimum number of diffractive zones for effective chromatic correction in the LWIR

    Science.gov (United States)

    Ramsey, J. L.; Walsh, K. F.; Smith, M.; Deegan, J.

    2016-05-01

    With the move to smaller pixel sizes in the longwave IR region there has been a push for shorter focal length lenses that are smaller, cheaper and lighter and that resolve lower spatial frequencies. As a result lenses must have better correction for both chromatic and monochromatic aberrations. This leads to the increased use of aspheres and diffractive optical elements (kinoforms). With recent developments in the molding of chalcogenide materials these aspheres and kinoforms are more cost effective to manufacture. Without kinoforms the axial color can be on the order of 15 μm which degrades the performance of the lens at the Nyquist frequency. The kinoforms are now on smaller elements and are correcting chromatic aberration which is on the order of the design wavelength. This leads to kinoform structures that do not require large phase changes and therefore have 1.5 to just over 2 zones. The question becomes how many zones are required to correct small amounts of chromatic aberration in the system and are they functioning as predicted by the lens design software? We investigate both the design performance and the as-built performance of two designs that incorporate kinoforms for the correction of axial chromatic aberration.

  13. Effects of iron stress on chromatic adaptation by natural phytoplankton communities in the Southern Ocean

    NARCIS (Netherlands)

    van Leeuwe, M.A.; Timmermans, K.R.; Witte, H.J.; Kraay, G.W.; Veldhuis, M.J.W.; de Baar, H.J.W.

    1998-01-01

    Effects of iron stress on chromatic adaptation were studied in natural phytoplankton communities collected in the Pacific region of the Southern Ocean. Iron enrichment experiments (48 to 72 h) were performed, incubating plankton communities under white, green and blue light respectively, with and wi

  14. Measurement of chromatic dispersion of microstructured polymer fibers by white-light spectral interferometry

    DEFF Research Database (Denmark)

    Hlubina, Petr; Ciprian, Dalibor; Frosz, Michael Henoch;

    2009-01-01

    We present a white-light spectral interferometric method for measuring the chromatic dispersion of microstructured fibers made of polymethyl methacrylate (PMMA). The method uses an unbalanced Mach-Zehnder interferometer with the fiber of known length placed in one of the interferometer arms and t...

  15. Experimental demonstration of the maximum likelihood-based chromatic dispersion estimator for coherent receivers

    DEFF Research Database (Denmark)

    Borkowski, Robert; Johannisson, Pontus; Wymeersch, Henk;

    2014-01-01

    We perform an experimental investigation of a maximum likelihood-based (ML-based) algorithm for bulk chromatic dispersion estimation for digital coherent receivers operating in uncompensated optical networks. We demonstrate the robustness of the method at low optical signal-to-noise ratio (OSNR...

  16. On the chromatic number of a space with forbidden equilateral triangle

    International Nuclear Information System (INIS)

    We improve the Frankl-Rödl estimate for the product of the numbers of edges in uniform hypergraphs with forbidden cardinalities of the intersection of edges. By using this estimate, we obtain explicit bounds for the chromatic number of a space with forbidden monochromatic equilateral triangles. Bibliography: 31 titles

  17. Delay differential models in multimode laser dynamics: taking chromatic dispersion into account

    Science.gov (United States)

    Vladimirov, A. G.; Huyet, G.; Pimenov, A.

    2016-04-01

    A set of differential equations with distributed delay is derived for modeling of multimode ring lasers with intracavity chromatic dispersion. Analytical stability analysis of continuous wave regimes is performed and it is demonstrated that sufficiently strong anomalous dispersion can destabilize these regimes.

  18. Expression profiling of Crambe abyssinica under arsenate stress identifies genes and gene networks involved in arsenic metabolism and detoxification

    Directory of Open Access Journals (Sweden)

    Kandasamy Suganthi

    2010-06-01

    Full Text Available Abstract Background Arsenic contamination is widespread throughout the world and this toxic metalloid is known to cause cancers of organs such as liver, kidney, skin, and lung in human. In spite of a recent surge in arsenic related studies, we are still far from a comprehensive understanding of arsenic uptake, detoxification, and sequestration in plants. Crambe abyssinica, commonly known as 'abyssinian mustard', is a non-food, high biomass oil seed crop that is naturally tolerant to heavy metals. Moreover, it accumulates significantly higher levels of arsenic as compared to other species of the Brassicaceae family. Thus, C. abyssinica has great potential to be utilized as an ideal inedible crop for phytoremediation of heavy metals and metalloids. However, the mechanism of arsenic metabolism in higher plants, including C. abyssinica, remains elusive. Results To identify the differentially expressed transcripts and the pathways involved in arsenic metabolism and detoxification, C. abyssinica plants were subjected to arsenate stress and a PCR-Select Suppression Subtraction Hybridization (SSH approach was employed. A total of 105 differentially expressed subtracted cDNAs were sequenced which were found to represent 38 genes. Those genes encode proteins functioning as antioxidants, metal transporters, reductases, enzymes involved in the protein degradation pathway, and several novel uncharacterized proteins. The transcripts corresponding to the subtracted cDNAs showed strong upregulation by arsenate stress as confirmed by the semi-quantitative RT-PCR. Conclusions Our study revealed novel insights into the plant defense mechanisms and the regulation of genes and gene networks in response to arsenate toxicity. The differential expression of transcripts encoding glutathione-S-transferases, antioxidants, sulfur metabolism, heat-shock proteins, metal transporters, and enzymes in the ubiquitination pathway of protein degradation as well as several unknown

  19. In situ characterization of green rust in the presence of arsenate and phosphate in simulated oxidized and reduced environments.

    Science.gov (United States)

    Root, R. A.; O'Day, P. A.

    2008-12-01

    Nano- to micron-scale particles of mixed-valent iron hydroxide, specifically green rust (GR [FeII6- x(OH)y FeIIIx(OH)12-y]x+[Anionx- + H2O]x-), have been identified and studied as corrosion products of steel, and recently rediscovered in hydromorphic soils and sediments. Green rusts are intermediate phases produced by biotic and abiotic reductive dissolution of ferric oxyhydroxides, or by oxidation of dissolved ferrous iron. Adsorbed oxyanions can stabilize GR phases and inhibit the formation of thermodynamically favored iron phases such as magnetite or lepidocrocite in subsurface environments. This study used synchrotron XRD to characterize iron (hydr)oxide minerals precipitated from solution and subsequent aging products under different environmental conditions of pH and Eh. Here we show the in situ abiotic development of green rust and its stabilization by the addition of adsorbed oxyanions or alternatively, subsequent rapid transformation to magnetite or lepidocrocite in the absence of added anions. A closed batch reactor with an in-line capillary was used to expose the reaction products to continuous synchrotron radiation. Laue patterns were collected at time intervals of 3-5 minutes and used to detect the formation of crystalline iron (hydr)oxide minerals that precipitate as a function time and chemical perturbations to the system, i.e. changing the pH, redox potential, ratio of Fe2+ to OH- , and addition of an oxyanion, arsenate or phosphate. The reactions were monitored by observing the development of diagnostic green rust XRD d-spacing peak at 10.9 Å (300), the 3.29 Å (210) d- spacing for lepidocrocite, and the 2.53 Å (100) d-spacing for magnetite, with continuous in-line measurement of pH and ORP. We found that green rust was stabilized by the adsorption of arsenate and phosphate. In the presence of arsenate or phosphate at pH =7, green rust transformed to lepidocrocite after several hours when anoxic controls were removed. When pH and Eh were constant

  20. 100-D Area In Situ Redox Treatability Test for Chromate-Contaminated Groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Mark D.; Vermeul, Vincent R.; Szecsody, James E.; Fruchter, Jonathan S.

    2000-10-12

    A treatability test was conducted for the In Situ Redox Manipulation (ISRM) technology at the 100 D Area of the U. S. Department of Energy's Hanford Site. The target contaminant was dissolved chromate in groundwater. The ISRM technology creates a permeable subsurface treatment zone to reduce mobile chromate in groundwater to an insoluble form. The ISRM permeable treatment zone is created by reducing ferric iron to ferrous iron within the aquifer sediments, which is accomplished by injecting aqueous sodium dithionite into the aquifer and then withdrawing the reaction products. The goal of the treatability test was to create a linear ISRM barrier by injecting sodium dithionite into five wells. Well installation and site characterization activities began in spring 1997; the first dithionite injection took place in September 1997. The results of this first injection were monitored through the spring of 1998. The remaining four dithionite injections were carried out in May through July of 1998.These five injections created a reduced zone in the Hanford unconfined aquifer approximately 150 feet in length (perpendicular to groundwater flow) and 50 feet wide. The reduced zone extended over the thickness of the unconfined zone. Analysis of post-emplacement groundwater samples showed concentrations of chromate, in the reduced zone decreased from approximately 1.0 mg/L before the tests to below analytical detection limits (<0.007 mg/L). Chromate concentrations also declined in downgradient monitoring wells to as low as 0.020 mg/L. These data, in addition to results from pre-test reducible iron characterization, indicate the barrier should be effective for 20 to 25 years. The 100-D Area ISRM barrier is being expanded to a length of up to 2,300 ft to capture a larger portion of the chromate plume.

  1. Assessing chromate availability in tropical ultramafic soils using isotopic exchange kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Garnier, Jeremie; Quantin, Cecile [Univ. Paris Sud CNRS, Orsay (France); Echevarria, Guillaume [ENSAIA-INPL-INRA, Vandoeuvre-les-Nancy (France); Becquer, Thierry [IRD - Univ. Paris VI and XII, Montpellier (France)

    2009-10-15

    Background, aim, and scope The presence of labile chromate in the soils is an environmental problem because of its high toxicity. The isotopic exchange kinetics (IEK) methods have been shown to be a useful tool to measure the phytoavailability of major (P, K) and trace elements (Cd, Zn, Ni, Pb) in soils. This study focused on the potential of applying IEK for chromate to characterize its availability in two tropical ultramafic Ferralsols. Materials and methods Two Ferralsols (NIQ II and NIQ III) of the ultramafic complex of Niquelandia (Goias, Brazil), known to have a high content of extractable chromate, were investigated. We adapted IEK for chromate in order to distinguish different pools of available chromate according to their rate of exchange kinetic. Results The extractable Cr(III) ranged from 9 to 132 mg kg{sup -1}, whereas extractable Cr(VI) ranged from 64 to 1,014 mg kg{sup -1}. The intensity factor, i.e., concentration of soluble Cr, ranged from 78 to 231 {mu}g L{sup -1} in profile NIQ II and from 6 to 141 {mu}g L{sup -1} in profile NIQ III. The highest concentrations were found in both topsoils and in the NIQ II-5 horizon. Most of the Cr(VI) was labile in short (E{sub 0-1} {sub min}) or medium-term (E{sub 1} {sub min-24} {sub h}) in both soils. The E{sub 0-1} {sub min} and E{sub 1} {sub min-24} {sub h} represented 39 to 83% of labile Cr (VI) in NIQ II and 69 to 80% in NIQ III. A high quantity of Cr(VI) was thus extremely labile and highly available, particularly in NIQ II. Moreover, both soils had a high buffering capacity of soluble Cr(VI) by labile pools. (orig.)

  2. Surface-enhanced Raman imaging of intracellular bioreduction of chromate in Shewanella oneidensis.

    Directory of Open Access Journals (Sweden)

    Sandeep P Ravindranath

    Full Text Available This proposed research aims to use novel nanoparticle sensors and spectroscopic tools constituting surface-enhanced Raman spectroscopy (SERS and Fluorescence Lifetime imaging (FLIM to study intracellular chemical activities within single bioremediating microorganism. The grand challenge is to develop a mechanistic understanding of chromate reduction and localization by the remediating bacterium Shewanella oneidensis MR-1 by chemical and lifetime imaging. MR-1 has attracted wide interest from the research community because of its potential in reducing multiple chemical and metallic electron acceptors. While several biomolecular approaches to decode microbial reduction mechanisms exist, there is a considerable gap in the availability of sensor platforms to advance research from population-based studies to the single cell level. This study is one of the first attempts to incorporate SERS imaging to address this gap. First, we demonstrate that chromate-decorated nanoparticles can be taken up by cells using TEM and Fluorescence Lifetime imaging to confirm the internalization of gold nanoprobes. Second, we demonstrate the utility of a Raman chemical imaging platform to monitor chromate reduction and localization within single cells. Distinctive differences in Raman signatures of Cr(VI and Cr(III enabled their spatial identification within single cells from the Raman images. A comprehensive evaluation of toxicity and cellular interference experiments conducted revealed the inert nature of these probes and that they are non-toxic. Our results strongly suggest the existence of internal reductive machinery and that reduction occurs at specific sites within cells instead of at disperse reductive sites throughout the cell as previously reported. While chromate-decorated gold nanosensors used in this study provide an improved means for the tracking of specific chromate interactions within the cell and on the cell surface, we expect our single cell imaging

  3. Kinetics and mechanism of arsenate removal by nanosized iron oxide-coated perlite.

    Science.gov (United States)

    Mostafa, M G; Chen, Yen-Hua; Jean, Jiin-Shuh; Liu, Chia-Chuan; Lee, Yao-Chang

    2011-03-15

    This study discussed the adsorption kinetics of As(V) onto nanosized iron oxide-coated perlite. The effects of pH, initial concentration of As(V) and common anions on the adsorption efficiency were also investigated. It was observed that a 100% As(V) adsorption was achieved at pH value of 4-8 from the initial concentration containing 1.0 mg-As(V)L(-1) and the adsorption percentage depended on the initial concentration; the phosphate and silicate ions would not interfere with the adsorption efficiency. Furthermore, nanosized iron oxide-coated perlite (IOCP) has been shown to be an effective adsorbent for the removal of arsenate from water. The adsorption kinetics were studied using pseudo-first- and pseudo-second-order models, and the experimental data fitted well with the pseudo-second-order model. Moreover, it suggests that the Langmuir isotherm is more adequate than the Freundlich isotherm in simulating the adsorption isotherm of As(V). The adsorption rate constant is 44.84 L mg(-1) and the maximum adsorption capacity is 0.39 mg g(-1). These findings indicate that the adsorption property of IOCP gives the compound a great potential for applications in environmental remediation.

  4. Tolerance, arsenic uptake, and oxidative stress in Acacia farnesiana under arsenate-stress.

    Science.gov (United States)

    Alcantara-Martinez, Nemi; Guizar, Sandra; Rivera-Cabrera, Fernando; Anicacio-Acevedo, Blanca E; Buendia-Gonzalez, Leticia; Volke-Sepulveda, Tania

    2016-07-01

    Acacia farnesiana is a shrub widely distributed in soils heavily polluted with arsenic in Mexico. However, the mechanisms by which this species tolerates the phytotoxic effects of arsenic are unknown. This study aimed to investigate the tolerance and bioaccumulation of As by A. farnesiana seedlings exposed to high doses of arsenate (AsV) and the role of peroxidases (POX) and glutathione S-transferases (GST) in alleviating As-stress. For that, long-period tests were performed in vitro under different AsV treatments. A. farnesiana showed a remarkable tolerance to AsV, achieving a half-inhibitory concentration (IC50) of about 2.8 mM. Bioaccumulation reached about 940 and 4380 mg As·kg(-1) of dry weight in shoots and roots, respectively, exposed for 60 days to 0.58 mM AsV. Seedlings exposed to such conditions registered a growth delay during the first 15 days, when the fastest As uptake rate (117 mg kg(-1) day(-1)) occurred, coinciding with both the highest rate of lipid peroxidation and the strongest up-regulation of enzyme activities. GST activity showed a strong correlation with the As bioaccumulated, suggesting its role in imparting AsV tolerance. This study demonstrated that besides tolerance to AsV, A. farnesiana bioaccumulates considerable amounts of As, suggesting that it may be useful for phytostabilization purposes. PMID:26618535

  5. Arsenate (As) uptake by and distribution in two cultivars of winter wheat (Triticum aestivum L.).

    Science.gov (United States)

    Geng, Chun-Nu; Zhu, Yong-Guan; Tong, Yi-Ping; Smith, Sally E; Smith, F A

    2006-01-01

    Two cultivars of winter wheat (Triticum aestivum L.) (Jing 411 and Lovrin 10) were used to investigate arsenate (As) uptake and distribution in plants grown in hydroponic culture and in the soil. Results showed that without As addition, Lovrin 10 had higher biomass than Jing 411 in the soil pot experiment; in the hydroponic experiment Lovrin 10 had similar root biomass to and lower shoot biomass than Jing 411. Increasing P supply from 32 to 161 microM resulted in lower tissue As concentrations, and increasing As supply from 0 to 2,000 microM resulted in lower tissue P concentrations. Increasing P supply tended to increase shoot-to-root ratios of As concentrations, and increasing As supply tended to decrease shoot-to-root ratios of As concentrations. Both cultivars invested more in root production under P deficient conditions than under P sufficient conditions. Lovrin 10 invested more biomass production to roots than Jing 411, which might be partly responsible for higher shoot P and As concentrations and higher shoot-to-root ratios of As concentrations. Moreover, Lovrin 10 allocated less As to roots than Jing 411 and the difference disappeared with decreasing P supply. PMID:16081139

  6. Co-adsorption of Trichloroethylene and Arsenate by Iron-Impregnated Granular Activated Carbon.

    Science.gov (United States)

    Deng, Baolin; Kim, Eun-Sik

    2016-05-01

    Co-adsorption of trichloroethylene (TCE) and arsenate [As(V)] was investigated using modified granular activated carbons (GAC): untreated, sodium hypochlorite-treated (NaClO-GAC), and NaClO with iron-treated GAC (NaClO/Fe-GAC). Batch experiments of single- [TCE or As(V)] and binary- [TCE and As(V)] components solutions are evaluated through Langmuir and Freundlich isotherm models and adsorption kinetic tests. In the single-component system, the adsorption capacity of As(V) was increased by the NaClO-GAC and the NaClO/Fe-GAC. The untreated GAC showed a low adsorption capacity for As(V). Adsorption of TCE by the NaClO/Fe-GAC was maximized, with an increased Freundlich constant. Removal of TCE in the binary-component system was decreased 15% by the untreated GAC, and NaClO- and NaClO/Fe-GAC showed similar efficiency to the single-component system because of the different chemical status of the GAC surfaces. Results of the adsorption isotherms of As(V) in the binary-component system were similar to adsorption isotherms of the single-component system. The adsorption affinities of single- and binary-component systems corresponded with electron transfer, competitive adsorption, and physicochemical properties.

  7. Arsenate (As V) in water: quantitative sensitivity relationships among biomarker, ecotoxicity and genotoxicity endpoints.

    Science.gov (United States)

    Silva, Valéria C; Almeida, Sônia M; Resgalla, Charrid; Masfaraud, Jean-François; Cotelle, Sylvie; Radetski, Claudemir M

    2013-06-01

    It is useful to test ecotoxicity and genotoxicity endpoints in the environmental impact assessment. Here, we compare and discuss ecotoxicity and genotoxicity effects in organisms in response to exposure to arsenate (As V) in solution. Eco(geno)toxicity responses in Aliivibrio fischeri, Lytechinus variegatus, Daphnia magna, Skeletonema costatum and Vicia faba were analyzed by assessing different endpoints: biomass growth, peroxidase activity, mitotic index, micronucleus frequency, and lethality in accordance with the international protocols. Quantitative sensitivity relationships (QSR) between these endpoints were established in order to rank endpoint sensitivity. The results for the QSR values based on the lowest observed effect concentration (LOEC) ratios varied from 2 (for ratio of root peroxidase activity to leaf peroxidase activity) to 2286 (for ratio of higher plant biomass growth to root peroxidase activity). The QSR values allowed the following sensitivity ranking to be established: higher plant enzymatic activity>daphnids≈echinoderms>bacteria≈algae>higher plant biomass growth. The LOEC values for the mitotic index and micronucleus frequency (LOEC=0.25mgAsL(-1)) were similar to the lowest LOEC values observed in aquatic organisms. This approach to the QSR of different endpoints could form the basis for monitoring and predicting early effects of pollutants before they give rise to significant changes in natural community structures. PMID:23597676

  8. Effect of arsenate As (V) on the biomarkers of Myriophyllum alterniflorum in oligotrophic and eutrophic conditions.

    Science.gov (United States)

    Krayem, M; Deluchat, V; Rabiet, M; Cleries, K; Lenain, J F; Saad, Z; Kazpard, V; Labrousse, P

    2016-03-01

    Alternate watermilfoil, Myriophyllum alterniflorum is an aquatic macrophyte found in the Limousin rivers (France) whose potential for biomonitoring of metal pollution has been demonstrated. The objective of the present study carried out in vitro was to identify biomarkers for an early detection of the pollution by a metalloid As (V) in eutrophic and oligotrophic conditions. A synthetic medium of similar composition to the waters of the River Vienne was prepared. The morphological development of watermilfoil was monitored for 30 days, with or without contamination by 100 μg L(-1) As (V). In addition, the mineralization of plants and the analysis of biomarkers (chlorophylls, photosynthetic and respiratory intensities …) were investigated after 21 days. Our results indicated that eutrophic medium, induced a decrease in chlorophyll pigments, in growth and an increase in H2O2 compared to the oligotrophic medium. While, the presence of As (V), led to a decrease in the osmotic potential, pigment content, photosynthesis and respiration rates and an inhibition of shoot branching of plants in both conditions. However, a significant increase in H2O2 content was noted in the eutrophic medium. Finally, As (V) was found to be more accumulated in roots than shoots in both conditions but was more accumulated in oligotrophic one. Therefore, we can conclude that the water trophic level modifies the response of M. alterniflorum in presence of arsenate. Thus, M. alterniflorum shows a great promise in water-quality biomonitoring. PMID:26766024

  9. Effect of arsenate As (V) on the biomarkers of Myriophyllum alterniflorum in oligotrophic and eutrophic conditions.

    Science.gov (United States)

    Krayem, M; Deluchat, V; Rabiet, M; Cleries, K; Lenain, J F; Saad, Z; Kazpard, V; Labrousse, P

    2016-03-01

    Alternate watermilfoil, Myriophyllum alterniflorum is an aquatic macrophyte found in the Limousin rivers (France) whose potential for biomonitoring of metal pollution has been demonstrated. The objective of the present study carried out in vitro was to identify biomarkers for an early detection of the pollution by a metalloid As (V) in eutrophic and oligotrophic conditions. A synthetic medium of similar composition to the waters of the River Vienne was prepared. The morphological development of watermilfoil was monitored for 30 days, with or without contamination by 100 μg L(-1) As (V). In addition, the mineralization of plants and the analysis of biomarkers (chlorophylls, photosynthetic and respiratory intensities …) were investigated after 21 days. Our results indicated that eutrophic medium, induced a decrease in chlorophyll pigments, in growth and an increase in H2O2 compared to the oligotrophic medium. While, the presence of As (V), led to a decrease in the osmotic potential, pigment content, photosynthesis and respiration rates and an inhibition of shoot branching of plants in both conditions. However, a significant increase in H2O2 content was noted in the eutrophic medium. Finally, As (V) was found to be more accumulated in roots than shoots in both conditions but was more accumulated in oligotrophic one. Therefore, we can conclude that the water trophic level modifies the response of M. alterniflorum in presence of arsenate. Thus, M. alterniflorum shows a great promise in water-quality biomonitoring.

  10. Co-adsorption of Trichloroethylene and Arsenate by Iron-Impregnated Granular Activated Carbon.

    Science.gov (United States)

    Deng, Baolin; Kim, Eun-Sik

    2016-05-01

    Co-adsorption of trichloroethylene (TCE) and arsenate [As(V)] was investigated using modified granular activated carbons (GAC): untreated, sodium hypochlorite-treated (NaClO-GAC), and NaClO with iron-treated GAC (NaClO/Fe-GAC). Batch experiments of single- [TCE or As(V)] and binary- [TCE and As(V)] components solutions are evaluated through Langmuir and Freundlich isotherm models and adsorption kinetic tests. In the single-component system, the adsorption capacity of As(V) was increased by the NaClO-GAC and the NaClO/Fe-GAC. The untreated GAC showed a low adsorption capacity for As(V). Adsorption of TCE by the NaClO/Fe-GAC was maximized, with an increased Freundlich constant. Removal of TCE in the binary-component system was decreased 15% by the untreated GAC, and NaClO- and NaClO/Fe-GAC showed similar efficiency to the single-component system because of the different chemical status of the GAC surfaces. Results of the adsorption isotherms of As(V) in the binary-component system were similar to adsorption isotherms of the single-component system. The adsorption affinities of single- and binary-component systems corresponded with electron transfer, competitive adsorption, and physicochemical properties. PMID:27131303

  11. Interactive effects of arsenate, selenium, and dietary protein on survival, growth, and physiology in mallard ducklings

    Science.gov (United States)

    Hoffman, D.J.; Sanderson, C.J.; LeCaptain, L.J.; Cromartie, E.; Pendleton, G.W.

    1992-01-01

    High concentrations of arsenic (As) and selenium (Se) have been found in aquatic food chains associated with irrigation drainwater. Total biomass of invertebrates, a maJor source of protein for wild ducklings, may vary in environments that are contaminated with selenium. Dayold mallard (Anas platyrhynchos) ducklings received an untreated diet (controls) containing 22% protein or diets containing 15 ppm Se (as selenomethionine), 60 ppm Se, 200 ppm As (as sodium arsenate), 15 ppm Se with 200 ppm As, or 60 ppm Se with 200 ppm As. In a concurrent experiment, the same sequence was repeated with a proteinrestricted (7%) but isocaloric diet. After 4 weeks, blood and tissue samples were collected for biochemical and histological examination. With 22% protein and 60 ppm Se in the diet, duckling survival and growth was reduced and livers had histopathological lesions. Arsenic alone caused some reduction in growth. Antagonistic interactive effects occurred between As and Se, including complete to partial alleviation of the following Se effects: mortality, impaired growth, hepatic lesions and lipid peroxidation, and altered glutathione and thiol status. With 7% protein, survival and growth of controls was less than that with 22% protein, Se (60 ppm) caused 100% mortality, and As (200 ppm) caused mortality, decreased growth, and liver histopathology. These findings suggest the potential for antagonistic effects of Se and As on duckling survival, growth, and physiology with adequate dietary protein but more severe toxicological effects when dietary protein is diminished.

  12. Competitive sorption and diffusion of chromate and sulphate in a flow system with goethite in gel beads.

    Science.gov (United States)

    van Beinum, Wendy; Meeussen, Johannes C L; van Riemsdijk, Willem H

    2006-08-10

    Column experiments and model simulations were employed to evaluate the processes involved in multicomponent solute transport in a system with heterogeneous flow. Column experiments were performed with goethite embedded in polyacrylamide gel beads. The gel forms an immobile water region that can be accessed by diffusion. A two-region transport model with diffusion into spheres was combined with a surface complexation model to predict reactive transport in the goethite-gel bead system. Chromate and sulphate breakthrough curves were measured in a set of transport experiments, along with corresponding changes in the pH of the effluent. Sorption and transport of sulphate and chromate in separate columns were predicted from independently measured sorption parameters. The model overestimated the pH changes in the effluent, possibly because of proton buffering by the polyacrylamide gel. The effect of competitive sorption on transport was examined in experiments with both anions present. The model predicted the effect of competition very well in a system initially equilibrated with sulphate, followed by infiltration with chromate. However, when sulphate was infiltrated after equilibration with chromate, chromate desorption and sulphate adsorption were clearly overestimated by the transport model. The exchange between the more strongly bound chromate and the sulphate added subsequently may be too slow to cause a substantial chromate peak in the effluent. This suggests that the local equilibrium assumption was not applicable in this case.

  13. Combining material characterization with single and multi-oxyanion adsorption for mechanistic study of chromate removal by cationic hydrogel

    Institute of Scientific and Technical Information of China (English)

    Irene M. C. Lo; Ke Yin; Samuel C. N. Tang

    2011-01-01

    Cationic hydrogel with magnetic property was synthesized via radical polymerization and its removal capacity of chromate from contaminated water was found to be 200 mg/g.Using Fourier transform infrared spectroscopy (FT-IR) study, the mechanism of chromate removal by hydrogel was found to be non-specific adsorption, mainly due to ion exchange, as evidenced by the positively charged functional group, trimethyl ammonium -N+(CH3)3.in the monomer.Verifications were accordingly determined by testing different oxyanion adsorption onto the hydrogel.The results of the chromate adsorption experiments illustrated that the amount of chromate adsorbed was nearly equal to that of the chloride released from the hydrogel, which is part of the evidence for ion exchange.Single and multi-oxyanion adsorption experiments were also performed, and it was demonstrated that ion removal was species independent, but charge dependent, another characteristic of the ion exchange process.It was found that the same Langmuir model can be applied to best fit the findings of single and multi-oxyanion adsorption, which further indicates the mechanism of chromate removal is attributed to ion exchange.In view of the above, the background anions compete for adsorption sites with chromate,evidenced by inhibitive chromate removal in the presence of background electrolytes in the batch studies, further echoing the ion exchange mechanism.

  14. A SAM-dependent methyltransferase cotranscribed with arsenate reductase alters resistance to peptidyl transferase center-binding antibiotics in Azospirillum brasilense Sp7.

    Science.gov (United States)

    Singh, Sudhir; Singh, Chhaya; Tripathi, Anil Kumar

    2014-05-01

    The genome of Azospirillum brasilense harbors a gene encoding S-adenosylmethionine-dependent methyltransferase, which is located downstream of an arsenate reductase gene. Both genes are cotranscribed and translationally coupled. When they were cloned and expressed individually in an arsenate-sensitive strain of Escherichia coli, arsenate reductase conferred tolerance to arsenate; however, methyltransferase failed to do so. Sequence analysis revealed that methyltransferase was more closely related to a PrmB-type N5-glutamine methyltransferase than to the arsenate detoxifying methyltransferase ArsM. Insertional inactivation of prmB gene in A. brasilense resulted in an increased sensitivity to chloramphenicol and resistance to tiamulin and clindamycin, which are known to bind at the peptidyl transferase center (PTC) in the ribosome. These observations suggested that the inability of prmB:km mutant to methylate L3 protein might alter hydrophobicity in the antibiotic-binding pocket of the PTC, which might affect the binding of chloramphenicol, clindamycin, and tiamulin differentially. This is the first report showing the role of PrmB-type N5-glutamine methyltransferases in conferring resistance to tiamulin and clindamycin in any bacterium.

  15. China Copper Processing Industry Focus

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>1. Market Consumption The ’China Factor’ and Copper Price Fluctuation We all know China is an enormous consumer of copper,but the exact levels of consumption and where the copper has gone remains a mystery.

  16. Comparison of four extraction procedures to assess arsenate and arsenite species in contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Giral, Melanie [Department of Civil, Geological and Mining Engineering, Ecole Polytechnique de Montreal, P.O. Box 6079, Station Centre-Ville, Montreal, Quebec H3C 3A7 (Canada); Zagury, Gerald J., E-mail: gerald.zagury@polymtl.c [Department of Civil, Geological and Mining Engineering, Ecole Polytechnique de Montreal, P.O. Box 6079, Station Centre-Ville, Montreal, Quebec H3C 3A7 (Canada); Deschenes, Louise [The Interuniversity Research Centre for the Life Cycle of Products, Processes and Services (CIRAIG), Department of Chemical Engineering, Ecole Polytechnique de Montreal, P.O. Box 6079, Station Centre-Ville, Montreal, Quebec H3C 3A7 (Canada); Blouin, Jean-Pierre [Centre d' expertise en analyse environnementale du Quebec, Ministere de l' Environnement, du Developpement Durable et des Parcs, 850, boulevard Vanier, Laval, Quebec H7C 2M7 (Canada)

    2010-05-15

    Inorganic arsenic in soils poses an important environmental concern. Several studies reported an oxidation of arsenite to arsenate during its extraction from soils. The objectives of this study were to (1) identify, among published procedures, an extraction method which preserves the oxidation state of arsenic and (2) to assess the influence of soil physicochemical properties on the performance of these methods. Four extraction strategies were compared: 1) 10 M HCl, 2) 15% (v/v) H{sub 3}PO{sub 4}, 3) 10 mM phosphate + 0.5% (w/v) NaDDC, and, 4) 1 M H{sub 3}PO{sub 4} + 0.5 M ascorbic acid (C{sub 6}H{sub 8}O{sub 6}). Separation and analysis of As species was performed by HPLC-ICP/MS. Oxidation of As(III) into As(V) during extraction was more important in soils with high content of Mn oxides. Extraction of arsenic from soils with 1 M H{sub 3}PO{sub 4} + 0.5 M C{sub 6}H{sub 8}O{sub 6} under microwaves was the best strategy to extract the majority of As while minimizing conversion of As(III) into As(V). - Extraction of arsenic from soils with 1 M H{sub 3}PO{sub 4} + 0.5 M C{sub 6}H{sub 8}O{sub 6} under microwaves is a suitable method to extract the majority of As while minimizing conversion of As(III) into As(V).

  17. Arsenate and cadmium co-adsorption and co-precipitation on goethite

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Wei [Environment Research Institute, Shandong University, Jinan 250100 (China); Lv, Jitao; Luo, Lei [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Yang, Kun [Department of Environmental Science, Zhejiang University, Hangzhou 310058 (China); Lin, Yongfeng; Hu, Fanbao [Environment Research Institute, Shandong University, Jinan 250100 (China); Zhang, Jing [State Key Laboratory of Synchrotron Radiation, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China); Zhang, Shuzhen, E-mail: szzhang@rcees.ac.cn [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)

    2013-11-15

    Highlights: • As enhances Cd adsorption amount on goethite. • Cd fixed through precipitation is more difficult to get released. • As in co-precipitates is easier to release than in its adsorption complexes. -- Abstract: Arsenate (As(V), AsO{sub 4}{sup 3−}) and cadmium (Cd) are among the toxic elements of most concern. Their sorption behaviors on goethite were studied by batch experiments (pH edges, isotherms and kinetics) and X-ray diffraction (XRD). Arsenic coordination environment was explored by X-ray absorbance fine structure (EXAFS) analysis. Sorption isotherms of both As(V) and Cd on goethite could be divided into the adsorption-dominated and precipitation-dominated parts, while their sorption showed different pH-dependency and sorption reversibility. Cadmium adsorption was enhanced in the presence of AsO{sub 4}{sup 3−}, which could be explained by the decrease in the electrostatic potential due to the sorption of AsO{sub 4}{sup 3−} and the formation of a ternary Cd–As(V)–goethite complex. Based on the EXAFS study, AsO{sub 4}{sup 3−} adsorbed on goethite mainly formed bidentate–binuclear complex. The high loadings of Cd changed the As(V)–Fe distance and its coordination number. However, Cd did not affect the As(V) adsorption amount in the adsorption-dominated region. When As(V) and Cd formed co-precipitates, their sorption amounts were both increased. The formation of co-precipitates decreased the mobility of Cd but increased the mobility of As(V) because less As(V) was sorbed on goethite through surface complexation. This study will provide better understandings on As(V) and Cd transport and useful information on their remediation strategies.

  18. ARSENATE BIOSORPTION BY IRON-MODIFIED PINE SAWDUST IN BATCH SYSTEMS: KINETICS AND EQUILIBRIUM STUDIES

    Directory of Open Access Journals (Sweden)

    María Aranzazú López-Leal,

    2012-02-01

    Full Text Available The biosorption of As(V from aqueous solutions by pine sawdust chemically modified with iron in batch systems was investigated. The loading process of Fe in this biomaterial was achieved by hydrolysis of two different ferric salts. This modification of sawdust is an attempt to improve As(V biosorption for practical applications. The kinetics and maximum biosorption capacities of the unmodified and modified pine sawdust were evaluated. It was found that the pseudo-second order model described the As(V biosorption kinetic data and the Langmuir-Freundlich equation described the arsenate sorption equilibrium. These results indicated that the sorption mechanism was chemisorption on a heterogeneous material. The pH effects governing biosorption capacities were also evaluated, showing a decrease as pH value rises, indicating that this biosorption process is highly pH-dependent. The estimated maximum biosorption capacities of As(V, based on the Langmuir-Freundlich fit to the data were, at pH 4, 4.4 mg/g of untreated sawdust, (UN-SW, 12.85 mg/g of ferric chloride modified sawdust (FeCl-SW, and 6 mg/g of ferric nitrate modified sawdust (FeNit-SW; and at pH 7, 2.6 mg/g of UN-SW, 5.9 mg/g of FeCl-SW, and 4.6 mg/g of FeNit-SW. Sorption capacities of iron-modified pine sawdust were evidently higher than other similar biosorbents previously reported.

  19. Functionalized chitosan electrospun nanofiber for effective removal of trace arsenate from water

    Science.gov (United States)

    Min, Ling-Li; Zhong, Lu-Bin; Zheng, Yu-Ming; Liu, Qing; Yuan, Zhi-Huan; Yang, Li-Ming

    2016-08-01

    An environment-friendly iron functionalized chitosan elctrospun nanofiber (ICS-ENF) was synthesized for trace arsenate removal from water. The ICS-ENF was fabricated by electrospinning a mixture of chitosan, PEO and Fe3+ followed by crosslinking with ammonia vapor. The physicochemical properties of ICS-ENF were characterized by FESEM, TEM-EDX and XRD. The ICS-ENF was found to be highly effective for As(V) adsorption at neutral pH. The As(V) adsorption occurred rapidly and achieved equilibrium within 100 min, which was well fitted by pseudo-second-order kinetics model. The As(V) adsorption decreased with increased ionic strength, suggesting an outer-sphere complexation of As(V) on ICS-ENF. Freundlich model well described the adsorption isotherm, and the maximum adsorption capacity was up to 11.2 mg/g at pH 7.2. Coexisting anions of chloride and sulfate showed negligible influence on As(V) removal, but phosphate and silicate significantly reduced As(V) adsorption by competing for adsorption sites. FTIR and XPS analysis demonstrated –NH, –OH and C–O were responsible for As(V) uptake. ICS-ENF was easily regenerated using 0.003 M NaOH, and the removal rate remained above 98% after ten successively adsorption-desorption recycles. This study extends the potential applicability of electrospun nanofibers for water purification and provides a promising approach for As(V) removal from water.

  20. Arsenic Retention in Foliage and Soil after Monosodium Methyl Arsenate (MSMA) Application to Turfgrass.

    Science.gov (United States)

    Matteson, Audrey R; Gannon, Travis W; Jeffries, Matthew D; Haines, Stephanie; Lewis, Dustin F; Polizzotto, Matthew L

    2014-01-01

    Monosodium methyl arsenate (MSMA) is a commonly used herbicide for weed control in turfgrass systems. There is concern that arsenic from applied MSMA could leach to groundwater or run off into surface water, thereby threatening human and ecosystem health. The USEPA has proposed a phase-out of the herbicide but is seeking additional research about the toxicity and environmental impacts of MSMA before establishing a final ruling. Little research has systematically investigated MSMA in field-based settings; instead, risks have been inferred from isolated field measurements or model-system studies. Accordingly, the overall goal of this study was to quantify the fate of arsenic after MSMA application to a managed turfgrass system. After MSMA application to turfgrass-covered and bareground lysimeters, the majority of arsenic was retained in turfgrass foliage and soils throughout year-long experiments, with 50 to 101% of the applied arsenic recovered in turfgrass systems and 55 to 66% recovered in bareground systems. Dissolved arsenic concentrations from 76.2-cm-depth pore water in the MSMA-treated soils were consistently adsorption isotherm experiments, MSMA retention by the sandy soil from our field site was markedly less than retention by a washed sand and a clay loam. Collectively, these results suggest that under aerobic conditions, minimal arsenic leaching to groundwater would occur after a typical application of MSMA to turfgrass. However, repeated MSMA application may pose environmental risks. Additional work is needed to examine arsenic cycling near the soil surface and to define arsenic speciation changes under different soil conditions. PMID:25602572

  1. Arsenate Accumulation, Distribution, and Toxicity Associated with Titanium Dioxide Nanoparticles in Daphnia magna.

    Science.gov (United States)

    Li, Mengting; Luo, Zhuanxi; Yan, Yameng; Wang, Zhenhong; Chi, Qiaoqiao; Yan, Changzhou; Xing, Baoshan

    2016-09-01

    Titanium dioxide nanoparticles (nano-TiO2) are widely used in consumer products. Nano-TiO2 dispersion could, however, interact with metals and modify their behavior and bioavailability in aquatic environments. In this study, we characterized and examined arsenate (As(V)) accumulation, distribution, and toxicity in Daphnia magna in the presence of nano-TiO2. Nano-TiO2 acts as a positive carrier, significantly facilitating D. magna's ability to uptake As(V). As nano-TiO2 concentrations increased from 2 to 20 mg-Ti/L, total As increased by a factor of 2.3 to 9.8 compared to the uptake from the dissolved phase. This is also supported by significant correlations between arsenic (As) and titanium (Ti) signal intensities at concentrations of 2.0 mg-Ti/L nano-TiO2 (R = 0.676, P distributed in BDM (biologically detoxified metal), but Ti was mainly distributed in MSF (metal-sensitive fractions) with increasing nano-TiO2 levels. Differences in subcellular distribution demonstrated that adsorbed As(V) carried by nano-TiO2 could dissociate itself and be transported separately, which results in increased toxicity at higher nano-TiO2 concentrations. Decreased As(V) toxicity associated with lower nano-TiO2 concentrations results from unaffected As levels in MSFs (when compared to the control), where several As components continued to be adsorbed by nano-TiO2. Therefore, more attention should be paid to the potential influence of nano-TiO2 on bioavailability and toxicity of cocontaminants. PMID:27485179

  2. Mutations in FMN Binding Pocket Diminish Chromate Reduction Rates for Gh-ChrR Isolated from Gluconacetobacter hansenii

    Energy Technology Data Exchange (ETDEWEB)

    Khaleel, Janin A.; Gong, Chunhong; Zhang, Yanfeng; Tan, Ruimin; Squier, Thomas C.; Jin, Hongjun

    2013-06-01

    A putative chromate ion binding site was identified proximal to a rigidly bound FMN from electron densities in the crystal structure of the quinone reductase from Gluconacetobacter hansenii (Gh-ChrR) (3s2y.pdb). To clarify the location of the chromate binding site, and to understand the role of FMN in the NADPH-dependent reduction of chromate, we have expressed and purified four mutant enzymes involving the site-specific substitution of individual side chains within the FMN binding pocket that form non-covalent bonds with the ribityl phosphate (i.e., S15A and R17A in loop 1 between β1 sheet and α1 helix) or the isoalloxanzine ring (E83A or Y84A in loop 4 between the β3 sheet and α4 helix). Mutations that selectively disrupt hydrogen bonds between either the N3 nitrogen on the isoalloxanzine ring (i.e., E83) or the ribitylphos- phoate (i.e., S15) respectively result in 50% or 70% reductions in catalytic rates of chromate reduction. In comparison, mutations that disrupt π-π ring stacking interactions with the isoal-loxanzine ring (i.e., Y84) or a salt bridge with the ribityl phosphate result in 87% and 97% inhibittion. In all cases there are minimal alterations in chromate binding affinities. Collectively, these results support the hypothesis that chromate binds proximal to FMN, and implicate a structural role for FMN positioning for optimal chromate reduction rates. As side chains proximal to the β3/α4 FMN binding loop 4 contribute to both NADH and metal ion binding, we propose a model in which structural changes around the FMN binding pocket couples to both chromate and NADH binding sites.

  3. Hexavalent chromium reduction by chromate-resistant haloalkaliphilic Halomonas sp. M-Cr newly isolated from tannery effluent

    OpenAIRE

    Mabrouk, Mona E.M.; Arayes, Mervat A.; Sabry, Soraya A.

    2014-01-01

    The current study aimed to isolate and characterize a chromate-resistant bacterium from tannery effluent, able to reduce Cr(VI) aerobically at high pH and salinity. Environmental contamination by hexavalent chromium, Cr(VI), presents a serious public health problem. Enrichment led to the isolation of 12 bacteria displaying different degrees of chromate reduction. Phenotypic characterization and phylogenetic analysis based on 16S rDNA sequence comparison indicated that the most potent strain b...

  4. Chromate Reductase YieF from Escherichia coli Enhances Hexavalent Chromium Resistance of Human HepG2 Cells

    Directory of Open Access Journals (Sweden)

    Xuan Liu

    2015-05-01

    Full Text Available Hexavalent chromium (Cr(VI is a serious environmental pollutant and human toxicant. Mammalian cells are very sensitive to chromate as they lack efficient chromate detoxifying strategy, e.g., chromate-reducing genes that are widely present in prokaryotes. To test whether introduction of prokaryotic chromate-reducing gene into mammalian cells could render higher chromate resistance, an Escherichia coli chromate-reducing gene yieF was transfected into human HepG2 cells. The expression of yieF was measured in stably transfected cells HepG2-YieF by quantitative RT-PCR and found up-regulated by 3.89-fold upon Cr(VI induction. In chromate-reducing ability test, HepG2-YieF cells that harbored the reductase showed significantly higher reducing ability of Cr(VI than HepG2 control cells. This result was further supported by the evidence of increased Cr(VI-removing ability of crude cell extract of HepG2-YieF. Moreover, HepG2-YieF demonstrated 10% higher viability and decreased expression of GSH synthesizing enzymes under Cr(VI stress. Subcellular localization of YieF was determined by tracing GFP-YieF fusion protein that was detected in both nucleus and cytoplasm by laser confocal microscopy. Altogether, this study successfully demonstrated that the expression of a prokaryotic Cr(VI-reducing gene yieF endowed mammalian cell HepG2 with enhanced chromate resistance, which brought new insight of Cr(VI detoxification in mammalian cells.

  5. Chromate reduction is expedited by bacteria engineered to produce the compatible solute trehalose.

    Science.gov (United States)

    Frederick, Tamlyn M; Taylor, Erin A; Willis, Jennifer L; Shultz, Matthew S; Woodruff, Peter J

    2013-08-01

    The toxicity and solubility of chromium(VI) can be decreased by certain microbes that reduce chromium(VI) to chromium(III). However, these bacteria do not escape unscathed from this process. Chromium(VI) reduction damages the essential macromolecules of living systems. Trehalose protects organisms from chemical stress but has not been tested in the context of bioremediation. We engineered bacteria to produce trehalose and found that they then reduced 1 mM chromium(VI) to chromium(III), whereas wild-type cells were only able to reduce half that amount. Thus, by providing bacteria with a biochemical defense against the side-effects of chromate reduction may be a new approach to cleaning up sites that are contaminated with high levels of chromate. PMID:23563698

  6. Psychophysical Evaluation of Achromatic and Chromatic Vision of Workers Chronically Exposed to Organic Solvents

    International Nuclear Information System (INIS)

    The purpose of this paper was to evaluate achromatic and chromatic vision of workers chronically exposed to organic solvents through psychophysical methods. Thirty-one gas station workers (31.5 ± 8.4 years old) were evaluated. Psychophysical tests were achromatic tests (Snellen chart, spatial and temporal contrast sensitivity, and visual perimetry) and chromatic tests (Ishihara's test, color discrimination ellipses, and Farnsworth-Munsell 100 hue test FM100). Spatial contrast sensitivities of exposed workers were lower than the control at spatial frequencies of 20 and 30 cpd whilst the temporal contrast sensitivity was preserved. Visual field losses were found in 10-30 degrees of eccentricity in the solvent exposed workers. The exposed workers group had higher error values of FM100 and wider color discrimination ellipses area compared to the controls. Workers occupationally exposed to organic solvents had abnormal visual functions, mainly color vision losses and visual field constriction

  7. Correcting for color crosstalk and chromatic aberration in multicolor particle shadow velocimetry

    International Nuclear Information System (INIS)

    Color crosstalk and chromatic aberration can bias estimates of fluid velocity measured by color particle shadow velocimetry (CPSV), using multicolor illumination and a color camera. This article describes corrections to remove these bias errors, and their evaluation. Color crosstalk removal is demonstrated with linear unmixing. It is also shown that chromatic aberrations may be removed using either scale calibration, or by processing an image illuminated by all colors simultaneously. CPSV measurements of a fully developed turbulent pipe flow of glycerin were conducted. Corrected velocity statistics from these measurements were compared to both single-color PSV and LDV measurements and showed excellent agreement to fourth-order, to well into the viscous sublayer. Recommendations for practical assessment and correction of color aberration and color crosstalk are discussed. (paper)

  8. Investigating the influence of chromatic aberration and optical illumination bandwidth on fundus imaging in rats

    Science.gov (United States)

    Li, Hao; Liu, Wenzhong; Zhang, Hao F.

    2015-10-01

    Rodent models are indispensable in studying various retinal diseases. Noninvasive, high-resolution retinal imaging of rodent models is highly desired for longitudinally investigating the pathogenesis and therapeutic strategies. However, due to severe aberrations, the retinal image quality in rodents can be much worse than that in humans. We numerically and experimentally investigated the influence of chromatic aberration and optical illumination bandwidth on retinal imaging. We confirmed that the rat retinal image quality decreased with increasing illumination bandwidth. We achieved the retinal image resolution of 10 μm using a 19 nm illumination bandwidth centered at 580 nm in a home-built fundus camera. Furthermore, we observed higher chromatic aberration in albino rat eyes than in pigmented rat eyes. This study provides a design guide for high-resolution fundus camera for rodents. Our method is also beneficial to dispersion compensation in multiwavelength retinal imaging applications.

  9. A "Green" Passivation of Zinc containing surfaces as an alternative to chromate

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Maahn, Ernst emanuel; Møller, Per;

    1996-01-01

    With view to a replacement for chromate passivation, Molyphos was developed under the Danish Materials Programme I (MUP I). In the Danish Materials Programme II(MUP II), the further development of Molyphos a molybdate phosphate conversion coating has been undertaken by application of a sealer to...... give added protection against white rust formation of zinc coated components. Various coating systems have been investigated: The types of zinc plated coating include acid zinc, cyanide zinc, and Zn/Fe. Many types of sealer have been employed both water and solvent based. The coating systems have been...... exposed in salt spray tests, humidity tests, prohesion tests and field tests. The results show that a) barrel plated acid zinc specimens coated with Molyphos + sealer give comparable performance to chromate in field tests and b) a Zn/Fe substrate and Molyphos coating (plus selected sealer) gives...

  10. Psychophysical Evaluation of Achromatic and Chromatic Vision of Workers Chronically Exposed to Organic Solvents

    Directory of Open Access Journals (Sweden)

    Eliza Maria da Costa Brito Lacerda

    2012-01-01

    Full Text Available The purpose of this paper was to evaluate achromatic and chromatic vision of workers chronically exposed to organic solvents through psychophysical methods. Thirty-one gas station workers (31.5 ± 8.4 years old were evaluated. Psychophysical tests were achromatic tests (Snellen chart, spatial and temporal contrast sensitivity, and visual perimetry and chromatic tests (Ishihara's test, color discrimination ellipses, and Farnsworth-Munsell 100 hue test—FM100. Spatial contrast sensitivities of exposed workers were lower than the control at spatial frequencies of 20 and 30 cpd whilst the temporal contrast sensitivity was preserved. Visual field losses were found in 10–30 degrees of eccentricity in the solvent exposed workers. The exposed workers group had higher error values of FM100 and wider color discrimination ellipses area compared to the controls. Workers occupationally exposed to organic solvents had abnormal visual functions, mainly color vision losses and visual field constriction.

  11. Design of macro-filter-lens with simultaneous chromatic and geometric aberration correction.

    Science.gov (United States)

    Prasad, Dilip K; Brown, Michael S

    2014-01-01

    A macro-filter-lens design that can correct for chromatic and geometric aberrations simultaneously while providing for a long focal length is presented. The filter is easy to fabricate since it involves two spherical surfaces and a planar surface. Chromatic aberration correction is achieved by making all the rays travel the same optical distance inside the filter element (negative meniscus). Geometric aberration is corrected for by the lens element (plano-convex), which makes the output rays parallel to the optic axis. This macro-filter-lens design does not need additional macro lenses and it provides an inexpensive and optically good (aberration compensated) solution for macro imaging of objects not placed close to the camera.

  12. [A Method for Selecting Self-Adoptive Chromaticity of the Projected Markers].

    Science.gov (United States)

    Zhao, Shou-bo; Zhang, Fu-min; Qu, Xing-hua; Zheng, Shi-wei; Chen, Zhe

    2015-04-01

    The authors designed a self-adaptive projection system which is composed of color camera, projector and PC. In detail, digital micro-mirror device (DMD) as a spatial light modulator for the projector was introduced in the optical path to modulate the illuminant spectrum based on red, green and blue light emitting diodes (LED). However, the color visibility of active markers is affected by the screen which has unknown reflective spectrum as well. Here active markers are projected spot array. And chromaticity feature of markers is sometimes submerged in similar spectral screen. In order to enhance the color visibility of active markers relative to screen, a method for selecting self-adaptive chromaticity of the projected markers in 3D scanning metrology is described. Color camera with 3 channels limits the accuracy of device characterization. For achieving interconversion of device-independent color space and device-dependent color space, high-dimensional linear model of reflective spectrum was built. Prior training samples provide additional constraints to yield high-dimensional linear model with more than three degrees of freedom. Meanwhile, spectral power distribution of ambient light was estimated. Subsequently, markers' chromaticity in CIE color spaces was selected via maximization principle of Euclidean distance. The setting values of RGB were easily estimated via inverse transform. Finally, we implemented a typical experiment to show the performance of the proposed approach. An 24 Munsell Color Checker was used as projective screen. Color difference in the chromaticity coordinates between the active marker and the color patch was utilized to evaluate the color visibility of active markers relative to the screen. The result comparison between self-adaptive projection system and traditional diode-laser light projector was listed and discussed to highlight advantage of our proposed method.

  13. Combined influences of chromatic aberration and scattering in depth-resolved two-photon fluorescence endospectroscopy

    OpenAIRE

    Wu, Yicong; Li, Xingde

    2010-01-01

    The influence of chromatic aberration of an objective lens in two-photon fluorescence (TPF) endospectroscopy of scattering media has been systematically investigated through both experiments and numerical simulations. Experiments were carried out on a uniform 3D scattering gelatin phantom embedded with TiO2 granules (to mimic tissue scattering) and fluorescein-tagged polystyrene beads. It was found that fluorescence spectral intensity and lineshape varied as a function of depth when measured ...

  14. Nitration of phenolic compounds and oxidation of hydroquinones using tetrabutylammonium chromate and dichromate under aprotic conditions

    Indian Academy of Sciences (India)

    Ali Reza Pourali; Arezou Goli

    2011-01-01

    In this work, we have reported a mild, efficient and selective method for the mononitration of phenolic compounds using sodium nitrite in the presence of tetrabutylammonium dichromate (TBAD) and oxidation of hydroquinones to quinones with TBAD in CH2Cl2. Using this method, high yields of nitrophenols and quinones were obtained under neutral aprotic conditions. Tetrabutylammonium chromate (TBAC) can also be used as oxidant at same conditions.

  15. Seeing red: affect modulation and chromatic color responses on the Rorschach.

    Science.gov (United States)

    Malone, Johanna C; Stein, Michelle B; Slavin-Mulford, Jenelle; Bello, Iruma; Sinclair, S Justin; Blais, Mark A

    2013-01-01

    Psychoanalytic theories suggest that color perception on the Rorschach relates to affective modulation. However, this idea has minimal empirical support. Using a clinical sample, the authors explored the cognitive and clinical correlates of Rorschach color determinants and differences among four affective modulation subtypes: Controlled, Balanced, Under-Controlled, and Flooded. Subtypes were differentiated by measures of affective regulation, reality testing/confusion, and personality traits. Initial support for the relationship of chromatic color response styles and affective modulation was found. PMID:23428172

  16. Chromate-tolerant bacteria for enhanced metal uptake by Eichhornia crassipes (Mart.).

    Science.gov (United States)

    Abou-Shanab, R A I; Angle, J S; van Berkum, P

    2007-01-01

    A total of 85 chromate-resistant bacteria were isolated from the rhizosphere of water hyacinth grown in Mariout Lake, Egypt, as well as the sediment and water of this habitat. Only 4 (11%), 2 (8%), and 2 (8%) of isolates from each of the environments, respectively, were able to tolerate 200 mg Cr (VI) L(-1). When these eight isolates were tested for their ability to tolerate other metals or to reduce chromate, they were shown to also be resistant to Zn, Mn, and Pb, and to display different degrees of chromate reduction (28% to 95%) under aerobic conditions. The isolates with the higher chromate reduction rates from 42% to 95%, (RA1, RA2, RA3, RA5, RA7, and RA8) were genetically diverse according to RAPD analysis using four differentprimers. Bacterial isolates RA1, RA2, RA3, RAS, and RA8 had 16 S rRNA gene sequences that were most similar to Pseudomonas diminuta, Brevundimonas diminuta, Nitrobacteria irancium, Ochrobactrum anthropi, and Bacillus cereus, respectively. Water hyacinth inoculated with RA5 and RA8 increased Mn accumulation in roots by 2.4- and 1.2-fold, respectively, compared to uninoculated controls. The highest concentrations of Cr (0.4 g kg(-1)) and Zn (0.18 g kg(-1)) were accumulated in aerial portions of water hyacinth inoculated with RA3. Plants inoculated with RA1, RA2, RA3, RA5, RA7, and RA8 had 7-, 11-, 24-, 29-, 35-, and 21-fold, respectively, higher Cr concentrations in roots compared to the control. These bacterial isolates are potential candidates in phytoremediation for chromium removal. PMID:18246718

  17. The chromatic number of a graph of girth 5 on a fixed surface

    DEFF Research Database (Denmark)

    Thomassen, Carsten

    2003-01-01

    We prove a color extension result implying that, for every fixed surface S, there are only finitely many 4-color-critical graphs of girth 5 on S. The result is best possible in the sense that there are infinitely many 4-color-critical graphs of girth 4 on S, except when S is the sphere, As a cons......, As a consequence, the chromatic number of graphs of girth 5 on S can be found in polynomial time....

  18. A zero-free interval for chromatic polynomials of graphs with 3-leaf spanning trees

    DEFF Research Database (Denmark)

    Perrett, Thomas

    2016-01-01

    It is proved that if G is a graph containing a spanning tree with at most three leaves, then the chromatic polynomial of G has no roots in the interval (1,t1], where t1≈1.2904 is the smallest real root of the polynomial (t-2)6+4(t-1)2 (t-2)3-(t-1)4. We also construct a family of graphs containing...

  19. Comparison of gene expression profiles in chromate transformed BEAS-2B cells.

    Directory of Open Access Journals (Sweden)

    Hong Sun

    Full Text Available BACKGROUND: Hexavalent chromium [Cr(VI] is a potent human carcinogen. Occupational exposure has been associated with increased risk of respiratory cancer. Multiple mechanisms have been shown to contribute to Cr(VI induced carcinogenesis, including DNA damage, genomic instability, and epigenetic modulation, however, the molecular mechanism and downstream genes mediating chromium's carcinogenicity remain to be elucidated. METHODS/RESULTS: We established chromate transformed cell lines by chronic exposure of normal human bronchial epithelial BEAS-2B cells to low doses of Cr(VI followed by anchorage-independent growth. These transformed cell lines not only exhibited consistent morphological changes but also acquired altered and distinct gene expression patterns compared with normal BEAS-2B cells and control cell lines (untreated that arose spontaneously in soft agar. Interestingly, the gene expression profiles of six Cr(VI transformed cell lines were remarkably similar to each other yet differed significantly from that of either control cell lines or normal BEAS-2B cells. A total of 409 differentially expressed genes were identified in Cr(VI transformed cells compared to control cells. Genes related to cell-to-cell junction were upregulated in all Cr(VI transformed cells, while genes associated with the interaction between cells and their extracellular matrices were down-regulated. Additionally, expression of genes involved in cell proliferation and apoptosis were also changed. CONCLUSION: This study is the first to report gene expression profiling of Cr(VI transformed cells. The gene expression changes across individual chromate exposed clones were remarkably similar to each other but differed significantly from the gene expression found in anchorage-independent clones that arose spontaneously. Our analysis identified many novel gene expression changes that may contribute to chromate induced cell transformation, and collectively this type of

  20. Proteomics reveals a core molecular response of Pseudomonas putida F1 to acute chromate challenge

    Directory of Open Access Journals (Sweden)

    McCarthy Andrea T

    2010-05-01

    Full Text Available Abstract Background Pseudomonas putida is a model organism for bioremediation because of its remarkable metabolic versatility, extensive biodegradative functions, and ubiquity in contaminated soil environments. To further the understanding of molecular pathways responding to the heavy metal chromium(VI [Cr(VI], the proteome of aerobically grown, Cr(VI-stressed P. putida strain F1 was characterized within the context of two disparate nutritional environments: rich (LB media and minimal (M9L media containing lactate as the sole carbon source. Results Growth studies demonstrated that F1 sensitivity to Cr(VI was impacted substantially by nutrient conditions, with a carbon-source-dependent hierarchy (lactate > glucose >> acetate observed in minimal media. Two-dimensional HPLC-MS/MS was employed to identify differential proteome profiles generated in response to 1 mM chromate under LB and M9L growth conditions. The immediate response to Cr(VI in LB-grown cells was up-regulation of proteins involved in inorganic ion transport, secondary metabolite biosynthesis and catabolism, and amino acid metabolism. By contrast, the chromate-responsive proteome derived under defined minimal growth conditions was characterized predominantly by up-regulated proteins related to cell envelope biogenesis, inorganic ion transport, and motility. TonB-dependent siderophore receptors involved in ferric iron acquisition and amino acid adenylation domains characterized up-regulated systems under LB-Cr(VI conditions, while DNA repair proteins and systems scavenging sulfur from alternative sources (e.g., aliphatic sulfonates tended to predominate the up-regulated proteome profile obtained under M9L-Cr(VI conditions. Conclusions Comparative analysis indicated that the core molecular response to chromate, irrespective of the nutritional conditions tested, comprised seven up-regulated proteins belonging to six different functional categories including transcription, inorganic ion

  1. Chromaticity calculations and code comparisons for x-ray lithography source XLS and SXLS rings

    International Nuclear Information System (INIS)

    This note presents the chromaticity calculations and code comparison results for the (x-ray lithography source) XLS (Chasman Green, XUV Cosy lattice) and (2 magnet 4T) SXLS lattices, with the standard beam optic codes, including programs SYNCH88.5, MAD6, PATRICIA88.4, PATPET88.2, DIMAD, BETA, and MARYLIE. This analysis is a part of our ongoing accelerator physics code studies. 4 figs., 10 tabs

  2. Chromaticity calculations and code comparisons for x-ray lithography source XLS and SXLS rings

    Energy Technology Data Exchange (ETDEWEB)

    Parsa, Z.

    1988-06-16

    This note presents the chromaticity calculations and code comparison results for the (x-ray lithography source) XLS (Chasman Green, XUV Cosy lattice) and (2 magnet 4T) SXLS lattices, with the standard beam optic codes, including programs SYNCH88.5, MAD6, PATRICIA88.4, PATPET88.2, DIMAD, BETA, and MARYLIE. This analysis is a part of our ongoing accelerator physics code studies. 4 figs., 10 tabs.

  3. Copper and silver halates

    CERN Document Server

    Woolley, EM; Salomon, M

    2013-01-01

    Copper and Silver Halates is the third in a series of four volumes on inorganic metal halates. This volume presents critical evaluations and compilations for halate solubilities of the Group II metals. The solubility data included in this volume are those for the five compounds, copper chlorate and iodate, and silver chlorate, bromate and iodate.

  4. Chromate and selenate hydrocalumite solid solutions and their applications in waste treatment

    Institute of Scientific and Technical Information of China (English)

    ZHANG Min; Eric J. Reardon

    2005-01-01

    Hydrocalumite, a calcium aluminate hydrate phase, consists of positively-charged structure units, and is therefore an ideal candidate for accommodating anionic contaminants. In this study, a series of batch experiments was carried out to examine the uptake of chromate and selenate by hydrocalumite. To determine the uptake capacity and long-term stability, hydrocalumite solid solutions between chromate/selenate and hydroxyl were synthesized over a reaction time of more than one year. At a ratio of water to initial solids added (CaAl2O4+CaO) of 75: 1, the maximum uptake capacities were over 77 and 114 g/kg for Cr and Se, respectively.These values are very close to the theoretical uptake capacities of chromate and selenate hydrocalumite end-members (81 and 118 g/kg, respectively). The oxyanion removal efficiency from solution was above 95%. Due to the high uptake capacity and anion removal efficiency of hydrocalumites, their application in wastewater treatment is promising. Hydrocalumites are also important hydration products of cementitious materials and the long-term stability of these phases is of significance for application in solidification/stabilization technology.

  5. Depth position detection for fast moving objects in sealed microchannel utilizing chromatic aberration.

    Science.gov (United States)

    Lin, Che-Hsin; Su, Shin-Yu

    2016-01-01

    This research reports a novel method for depth position measurement of fast moving objects inside a microfluidic channel based on the chromatic aberration effect. Two band pass filters and two avalanche photodiodes (APD) are used for rapid detecting the scattered light from the passing objected. Chromatic aberration results in the lights of different wavelengths focus at different depth positions in a microchannel. The intensity ratio of two selected bands of 430 nm-470 nm (blue band) and 630 nm-670 nm (red band) scattered from the passing object becomes a significant index for the depth information of the passing object. Results show that microspheres with the size of 20 μm and 2 μm can be resolved while using PMMA (Abbe number, V = 52) and BK7 (V = 64) as the chromatic aberration lens, respectively. The throughput of the developed system is greatly enhanced by the high sensitive APDs as the optical detectors. Human erythrocytes are also successfully detected without fluorescence labeling at a high flow velocity of 2.8 mm/s. With this approach, quantitative measurement for the depth position of rapid moving objects inside a sealed microfluidic channel can be achieved in a simple and low cost way. PMID:26858810

  6. 160 km all-optical OFDM transmission system with inline chromatic dispersion compensation

    Institute of Scientific and Technical Information of China (English)

    Xingyao Gu; Hongwei Chen; Minghua Chen; Shizhong Xie

    2012-01-01

    An experimental demonstration of an all-optical sampling orthogonal frequency division multiplexing (AOS-OFDM) transmission system with inline chromatic dispersion (CD) compensation is carried out to test the nonlinear influence. With five subcarriers non-return-to-zero (NRZ) modulated, the total bit rate is 50 Gb/s without polarization multiplexing. The receiver end is highly simplified with direct detection using optical Fourier transform filter. After transmission in 160-km standard single-mode fiber (SSMF) link with 130-ps/nm residual CD, an optimum input optical power for the system performance is achieved.%An experimental demonstration of an all-optical sampling orthogonal frequency division multiplexing (AOS-OFDM) transmission system with inline chromatic dispersion (CD) compensation is carried out to test the nonlinear influence.With five subcarriers non-return-to-zero (NRZ) modulated,the total bit rate is 50 Gb/s without polarization multiplexing.The receiver end is highly simplified with direct detection using optical Fourier transform filter.After transmission in 160-km standard single-mode fiber (SSMF) link with 130-ps/nm residual CD,an optimum input optical power for the system performance is achieved.Optical orthogonal frequency division multiplexing (OOFDM) method has recently drawn increasing attention as a promising technology for future high-speed optical communication systems[1,2].O-OFDM has high tolerance to chromatic dispersion (CD),polarization mode dispersion,and optical nonlinearity[3-5].

  7. Characterisation of Vranec, Cabernet sauvignon and Merlot wines based on their chromatic and anthocyanin profiles

    Directory of Open Access Journals (Sweden)

    Dimitrovska Maja

    2013-01-01

    Full Text Available Wines of three different grape varieties, Vranec, Cabernet Sauvignon and Merlot were examined for their characterisation in terms of anthocyanin and chromatic profiles, total polyphenols and antioxidant potential. Total, monomeric, polymeric and copigmented anthocyanins were determined by spectrophotometry and the individual anthocyanin compounds were quantified using HPLC-DAD. Chromatic profile was evaluated according to colour density, hue, % red, % blue, % yellow and brilliance (% dA. The established data were submitted to analysis of variance and principle component analysis in order to evaluate their potential for differentiation of wines according to variety and vintage. Vranec wines have shown distinctive characteristics, with the highest content of anthocyanins and values of colour intensity, % red and % dA, compared to the other two studied varieties. The content of petunidin-3-glucoside, peonindin-3-glucoside and anthocyanin acetates were established as possible markers for differentiation of Vranec wines from Cabernet Sauvignon and Merlot wines. However, none of the assayed parameters could be used for differentiation of Cabernet Sauvignon from Merlot wines. It was observed that wine age limits successful classification of the wines by variety according to anthocyanins. The chromatic parameters allowed distinguishing of young (aged up to 1 year from old Vranec wines.

  8. The male blue crab, Callinectes sapidus, uses both chromatic and achromatic cues during mate choice.

    Science.gov (United States)

    Baldwin, Jamie; Johnsen, Sönke

    2012-04-01

    In the blue crab, Callinectes sapidus, claw color varies by sex, sexual maturity and individual. Males rely in part on color cues to select appropriate mates, and these chromatic cues may be perceived through an opponent interaction between two photoreceptors with maximum wavelength sensitivities at 440 and 508 nm. The range of color discrimination of this dichromatic visual system may be limited, however, and it is unclear whether male blue crabs are capable of discriminating the natural variations in claw color that may be important in mate choice. By testing males' innate color preferences in binary choice tests between photographs of red-clawed females and six variations of orange-clawed females, we examined both the chromatic (opponent interaction) and achromatic (relative luminance) cues used in male mate choice. Males significantly preferred red-clawed females to orange-clawed females, except when the test colors were similar in both opponency and relative luminance. Our results are unusual in that they indicate that male mate choice in the blue crab is not guided solely by achromatic or chromatic mechanisms, suggesting that both color and intensity are used to evaluate female claw color.

  9. Chromatic multifocal pupillometer for objective perimetry in patients with macular degeneration (Conference Presentation)

    Science.gov (United States)

    Rotenstreich, Ygal; Ben-Ner, Daniel; Mahajna, Mohamad; Chibel, Ron; Sher, Ifat

    2016-03-01

    Purpose: To objectively assess visual field (VF) defects and retinal cell function in healthy subjects and patients with macular degeneration using a chromatic multifocal pupillometer. Methods: A multifocal chromatic pupillometer (MCP) was used to record pupillary responses (PR) of 17 healthy subjects and 5 Best Vitelliform macular dystrophy patients. Blue and red light stimuli (peak 485nm and 620nm, respectively) were presented at light intensities of 400 and 1000 cd/m2, respectively at 76 different points in a 16.2 degree VF. The PR of patients were compared with their findings on Humphrey's 24-2 perimetry, optical coherence tomography and the PR obtained from healthy subjects. Results: Patients demonstrated reduced percentage of pupillary contraction and slower maximal contraction velocity, more than two standard errors (SE) away from the mean of healthy subjects in response to red light in majority of VF locations. In response to blue light, the percentage of pupillary contraction was lower (by over two SE) compared with normal controls only in central locations. The latency of maximal contraction velocity was shorter in patients compared with healthy subjects in response to both colors. Conclusions: This study demonstrated the advantage of using MCP-based objective VF to assess central scotoma in macular degeneration. Our finding also suggests that chromatic perimetry may differentiate between PR mediated by cones and rods, and can specifically detect defects in macular cones. Different parameters of PR such as latency of maximal contraction velocity may shed light on the pathophysiology of different blinding diseases.

  10. Chromatic energy filter and characterization of laser-accelerated proton beams for particle therapy

    Science.gov (United States)

    Hofmann, Ingo; Meyer-ter-Vehn, Jürgen; Yan, Xueqing; Al-Omari, Husam

    2012-07-01

    The application of laser accelerated protons or ions for particle therapy has to cope with relatively large energy and angular spreads as well as possibly significant random fluctuations. We suggest a method for combined focusing and energy selection, which is an effective alternative to the commonly considered dispersive energy selection by magnetic dipoles. Our method is based on the chromatic effect of a magnetic solenoid (or any other energy dependent focusing device) in combination with an aperture to select a certain energy width defined by the aperture radius. It is applied to an initial 6D phase space distribution of protons following the simulation output from a Radiation Pressure Acceleration model. Analytical formula for the selection aperture and chromatic emittance are confirmed by simulation results using the TRACEWIN code. The energy selection is supported by properly placed scattering targets to remove the imprint of the chromatic effect on the beam and to enable well-controlled and shot-to-shot reproducible energy and transverse density profiles.

  11. Chromaticity and color saturation of ultraviolet irradiated poly(vinyl alcohol)-anthocyanin coatings

    Science.gov (United States)

    Mat Nor, N. A.; Aziz, N.; Mohd-Adnan, A. F.; Taha, R. M.; Arof, A. K.

    2016-06-01

    The purpose of this paper is to evaluate the chromaticity and color saturation of anthocyanin extraction from fruit pericarps of Ixora siamensis in a poly(vinyl alcohol) (PVA) matrix. The colored PVA matrix was exposed to UV-B irradiation for 93 days at UV intensity of 17.55 lux. Anthocyanin colorant has been extracted using methanol acidified with 0.5% trifluoroacetic acid (TFA). Different concentrations of ferulic acid (FA) (0, 1, 2, 3, 4 and 5 wt.%) have been added to the anthocyanin extractions before mixing with PVA to form a coating system. The PVA-anthocyanin-FA mixtures have been coated on glass slides and kept overnight in the dark for curing before exposure to UV-B irradiation. The FA-free sample undergoes more color degradation compared to samples containing FA. The coating with 2% FA has the most stable color with chromaticity of 41% and color saturation of 0.88 compared to other FA containing coats. The FA-free coat exhibits 29% chromaticity and color saturation of 0.38 at the end of the experiment.

  12. ANALYSIS OF CHROMIUM BIOACCUMULATION IN BLOOD, URINE AND NAIL SAMPLES OF CHROMATE FACTORY WORKERS

    Directory of Open Access Journals (Sweden)

    M. JOB GOPINATH

    2006-01-01

    Full Text Available Industrial play a major role in country's economy. Air pollution is an occupational health problem in industries. Generaly, there are more man made pollution in the air of heavy industries and major cities around the industries, Exposure as inhalation represents one of the major routes by which the body can be exposed by accident or design to foreign materials. One having entered to the respiratory tract, inhaled materails may be readly absorbed or may react directly with the alveolar epithelium and entered in to the blood steam. These air pollution induce many changes in physiological and biochemical process. The present study was contucted on chromate industrial workers as these workers were repeatedly exposed to pollutants in chromium factors (Tamil Nadu Chromate and Chemical Ltd., Ranipet industrial Town, Tamil Nadu. The bioaccumulation of chromium was estimated from one hundred samples of blood and urine as well as twenty five samples of nails collected from TCC industrial workers and control subject. The workers and control subject were randomly selected. Estimation was carried out by Atomic Absorption spectrometry. From the results it was obeserved tha the accumulation of heavy metal chromium in the blood. urine and nail samples of chromate factory worker are above the normal ranges. Results are statistically significant.

  13. Estimation of chromatic errors from broadband images for high contrast imaging

    Science.gov (United States)

    Sirbu, Dan; Belikov, Ruslan

    2015-09-01

    Usage of an internal coronagraph with an adaptive optical system for wavefront correction for direct imaging of exoplanets is currently being considered for many mission concepts, including as an instrument addition to the WFIRST-AFTA mission to follow the James Web Space Telescope. The main technical challenge associated with direct imaging of exoplanets with an internal coronagraph is to effectively control both the diffraction and scattered light from the star so that the dim planetary companion can be seen. For the deformable mirror (DM) to recover a dark hole region with sufficiently high contrast in the image plane, wavefront errors are usually estimated using probes on the DM. To date, most broadband lab demonstrations use narrowband filters to estimate the chromaticity of the wavefront error, but this reduces the photon flux per filter and requires a filter system. Here, we propose a method to estimate the chromaticity of wavefront errors using only a broadband image. This is achieved by using special DM probes that have sufficient chromatic diversity. As a case example, we simulate the retrieval of the spectrum of the central wavelength from broadband images for a simple shaped- pupil coronagraph with a conjugate DM and compute the resulting estimation error.

  14. XPS characterization of (copper-based) coloured stains formed on limestone surfaces of outdoor Roman monuments.

    Science.gov (United States)

    Salvi, Anna Maria; Langerame, Fausto; Macchia, Andrea; Sammartino, Maria Pia; Tabasso, Marisa Laurenzi

    2012-01-01

    Limestone basements holding bronzes or other copper alloys artefacts such as sculptures, decorations and dedicatory inscriptions are frequently met both in modern and ancient monuments. In outdoor conditions, such a combination implies the corrosion products of the copper based alloy, directly exposed to rainwater, will be drained off and migrate through the porous surfaces, forming stains of different colours and intensities, finally causing the limestone structures to deteriorate.In this work we have analysed samples from two modern limestone monuments in Rome, the Botticino surfaces of the 'Vittoriano' (by G.Sacconi, 1885-1911- Piazza Venezia) and the travertine basement of the 'Statua dello Studente' (by A.Cataldi, 1920- University city, La Sapienza), and focussed our investigation on the chemical composition of the copper-stained zones using XPS (X-ray Photoelectron Spectroscopy) as a surface-specific technique.Based on observations reporting on the structure and bonding at the calcite surfaces we have identified copper complexes and mixed calcium/copper carbonates associated with the stains, as well as the chemical state of other elements therein included, and related the compositional changes with differences in chromatic characteristics and sampling locations. PMID:22594435

  15. Kunpeng Copper:The largest Copper Smelting Company of Sichuan

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>On September 9,Liangshan Mining Company’s 100,000 tons/year cathode copper project kicked off.It is another key project of the company following the successful launch of the 100,000 tons/year anode copper project.Based on ISA copper smelting technology of the largest open-cast copper mine in southwest China,

  16. Degradation of azurite in mural paintings: distribution of copper carbonate, chlorides and oxalates by SRFTIR

    Science.gov (United States)

    Lluveras, A.; Boularand, S.; Andreotti, A.; Vendrell-Saz, M.

    2010-05-01

    This article illustrates the analysis by synchrotron micro-analytical techniques of an azurite painting presenting greenish chromatic degradation. The challenge of the experiments was to obtain the spatial distribution of the degradation products of azurite. Copper hydroxychlorides, carbonates and copper oxalates have been mapped by SR FTIR imaging of cross sections in transmission mode. To complement the information, Py/GC/MS and GC/MS techniques were applied in order to characterize the binding media and organic materials present as well as their degradation products. Results contribute to a better understanding of the decay of blue areas in ancient paintings not only from the particular point of view of azurite weathering, but also by adding information regarding the oxalates’ formation and their distribution in painting samples. Synchrotron radiation demonstrates its capability for the mapping in painting cross sections.

  17. Thermodynamics of arsenates, selenites, and sulfates in the oxidation zone of sulfide ores: I. Thermodynamic constants at ambient conditions

    Science.gov (United States)

    Charykova, M. V.; Krivovichev, V. G.; Depmeir, W.

    2010-12-01

    Understanding and deciphering processes proceeding near the surface are among the urgent tasks of contemporary mineralogy and geochemistry, which are especially important for resolving ecological challenges and developing principles of rational environmental management. The paper presents systematized data published on thermodynamics of minerals (arsenates, sulfates, selenites, and selenates), which are formed in the weathering zone of sulfide ores, and determines approaches to quantitative physicochemical modeling of their formation conditions. Diagrams of phase and chemical equilibria (Eh-pH, diagrams of solubility) of the subsystems of the model system Fe-Cu-Zn-Pb-Co-Ni-As-Se-S-H2O (Fe2+, Fe3+, Cu2+, Zn2+, Pb2+, Ni2+, Co2+, H+//SeO{3/2-}, SeO{4/2-}, AsO{4/3-}, SO{4/2-}, OH--H2O) are used as a thermodynamic basis for modeling mineral-forming processes in the weathering zone of ore deposits. Seventy-two arsenates, about 70 sulfates, and 7 selenites and selenates have been identified in the framework of this system. The available published values of standard thermodynamic functions of the formation of minerals and chemical compounds are given, as well as the Pitzer equation parameters to describe the sulfate systems, which are substantially specific due to the high solubility of their components.

  18. Post-column reaction for simultaneous analysis of chromatic and leuco forms of malachite green and crystal violet by high-performance liquid chromatography with photometric detection

    Science.gov (United States)

    Allen, J.L.; Meinertz, J.R.

    1991-01-01

    The chromatic and leuco forms of malachite green and crystal violet were readily separated and detected by a sensitive and selective high-performance liquid chromatographic procedure. The chromatic and leuco forms of the dyes were separated within 11 min on a C18 column with a mobile phase of 0.05 M sodium acetate and 0.05 M acetic acid in water (19%) and methanol (81%). A reaction chamber, containing 10% PbO2 in Celite 545, was placed between the column and the spectrophotometric detector to oxidize the leuco forms of the dyes to their chromatic forms. Chromatic and leuco malachite green were quantified by their absorbance at 618 nm; and chromatic and leuco Crystal Violet by their absorbance at 588 nm. Detection limits for chromatic and leuco forms of both dyes ranged from 0.12 to 0.28 ng. A linear range of 1 to 100 ng was established for both forms of the dyes.

  19. Fabricating Copper Nanotubes by Electrodeposition

    Science.gov (United States)

    Yang, E. H.; Ramsey, Christopher; Bae, Youngsam; Choi, Daniel

    2009-01-01

    Copper tubes having diameters between about 100 and about 200 nm have been fabricated by electrodeposition of copper into the pores of alumina nanopore membranes. Copper nanotubes are under consideration as alternatives to copper nanorods and nanowires for applications involving thermal and/or electrical contacts, wherein the greater specific areas of nanotubes could afford lower effective thermal and/or electrical resistivities. Heretofore, copper nanorods and nanowires have been fabricated by a combination of electrodeposition and a conventional expensive lithographic process. The present electrodeposition-based process for fabricating copper nanotubes costs less and enables production of copper nanotubes at greater rate.

  20. Targeting copper in cancer therapy: 'Copper That Cancer'.

    Science.gov (United States)

    Denoyer, Delphine; Masaldan, Shashank; La Fontaine, Sharon; Cater, Michael A

    2015-11-01

    Copper is an essential micronutrient involved in fundamental life processes that are conserved throughout all forms of life. The ability of copper to catalyze oxidation-reduction (redox) reactions, which can inadvertently lead to the production of reactive oxygen species (ROS), necessitates the tight homeostatic regulation of copper within the body. Many cancer types exhibit increased intratumoral copper and/or altered systemic copper distribution. The realization that copper serves as a limiting factor for multiple aspects of tumor progression, including growth, angiogenesis and metastasis, has prompted the development of copper-specific chelators as therapies to inhibit these processes. Another therapeutic approach utilizes specific ionophores that deliver copper to cells to increase intracellular copper levels. The therapeutic window between normal and cancerous cells when intracellular copper is forcibly increased, is the premise for the development of copper-ionophores endowed with anticancer properties. Also under investigation is the use of copper to replace platinum in coordination complexes currently used as mainstream chemotherapies. In comparison to platinum-based drugs, these promising copper coordination complexes may be more potent anticancer agents, with reduced toxicity toward normal cells and they may potentially circumvent the chemoresistance associated with recurrent platinum treatment. In addition, cancerous cells can adapt their copper homeostatic mechanisms to acquire resistance to conventional platinum-based drugs and certain copper coordination complexes can re-sensitize cancer cells to these drugs. This review will outline the biological importance of copper and copper homeostasis in mammalian cells, followed by a discussion of our current understanding of copper dysregulation in cancer, and the recent therapeutic advances using copper coordination complexes as anticancer agents.

  1. Arsenic on the Hands of Children after Playing in Playgrounds

    OpenAIRE

    Kwon, Elena; Zhang, Hongquan; Wang, Zhongwen; Jhangri, Gian S; Lu, Xiufen; Fok, Nelson; Gabos, Stephan; Li, Xing-Fang; Le, X. Chris

    2004-01-01

    Increasing concerns over the use of wood treated with chromated copper arsenate (CCA) in playground structures arise from potential exposure to arsenic of children playing in these playgrounds. Limited data from previous studies analyzing arsenic levels in sand samples collected from CCA playgrounds are inconsistent and cannot be directly translated to the amount of children’s exposure to arsenic. The objective of this study was to determine the quantitative amounts of arsenic on the hands of...

  2. Characterization and Low-Cost Remediation of Soils Contaminated by Timbers in Community Gardens

    OpenAIRE

    Heiger-Bernays, W.; Fraser, A.; Burns, V.; Diskin, K.; Pierotti, D.; Merchant-Borna, K.; McClean, M; Brabander, D.; Hynes, H. P.

    2009-01-01

    Urban community gardens worldwide provide significant health benefits to those gardening and consuming fresh produce from them. Urban gardens are most often placed in locations and on land in which soil contaminants reflect past practices and often contain elevated levels of metals and organic contaminants. Garden plot dividers made from either railroad ties or chromated copper arsenate (CCA) pressure treated lumber contribute to the soil contamination and provide a continuous source of conta...

  3. Method of removing arsenic and other anionic contaminants from contaminated water using enhanced coagulation

    Science.gov (United States)

    Teter, David M.; Brady, Patrick V.; Krumhansl, James L.; Khandaker, Nadim R.

    2006-11-21

    An improved water decontamination process comprising contacting water containing anionic contaminants with an enhanced coagulant to form an enhanced floc, which more efficiently binds anionic species (e.g., arsenate, arsenite, chromate, fluoride, selenate, and borate, and combinations thereof) predominantly through the formation of surface complexes. The enhanced coagulant comprises a trivalent metal cation coagulant (e.g., ferric chloride or aluminum sulfate) mixed with a divalent metal cation modifier (e.g., copper sulfate or zinc sulfate).

  4. SORPTION OF ARSENATE AND ARSENITE ON RUO2 X H2O: ANALYSIS OF SORBED PHASE OXIDATION STATE BY XANES IN ADVANCED PHOTON SOURCE ACTIVITY REPORT 2002

    Science.gov (United States)

    The sorption reactions of arsenate (As(V)) and arsenite (As(III)) on RuO2 x H2O were examined by X-ray Absorption Near Edge Spectroscopy (XANES) to elucidate the solid state speciation of sorbed As. At all pH values studied (pH 4-8), RuO2 x H

  5. Molecular characterization of two glutathione peroxidase genes in Mytilus galloprovincialis and their transcriptional responses to sub-chronic arsenate and cadmium exposure

    Directory of Open Access Journals (Sweden)

    Q Wang

    2014-05-01

    Full Text Available Glutathione peroxidases (GPxs are key enzymes in the antioxidant defense system of living organisms, and protect organisms against oxidative stresses. In this study, the full-length cDNA sequences encoding cytosolic GPx (MgcGPx and phospholipid-hydroperoxide GPx (MgGPx4 were identified from Mytilus galloprovincialis. The mussels were exposed to 0, 1, 10, and 100 μg/L cadmium and arsenate for 30 days. The mRNA transcripts of these two genes and total GPx activity were examined in the gills and digestive gland after contaminants exposure. The mussels exposed to cadmium and arsenate responded mainly by down-regulating MgcGPx and MgGPx4 mRNA transcription in gills and up-regulating transcription in digestive gland. However, total GPx activities increased following cadmium exposure but decreased after arsenate stress in both tissues. These results suggest that MgcGPx and MgGPx4 perhaps play an important role in maintaining cellular redox homeostasis and protecting M. galloprovincialis against cadmium and arsenate toxicity. It can also be inferred that these genes have the potential to be used as molecular biomarkers for assessing cellular stress and toxicity of contaminants in this mussel.

  6. LEP copper accelerating cavities

    CERN Multimedia

    Laurent Guiraud

    1999-01-01

    These copper cavities were used to generate the radio frequency electric field that was used to accelerate electrons and positrons around the 27-km Large Electron-Positron (LEP) collider at CERN, which ran from 1989 to 2000. The copper cavities were gradually replaced from 1996 with new superconducting cavities allowing the collision energy to rise from 90 GeV to 200 GeV by mid-1999.

  7. Copper wire bonding

    CERN Document Server

    Chauhan, Preeti S; Zhong, ZhaoWei; Pecht, Michael G

    2014-01-01

    This critical volume provides an in-depth presentation of copper wire bonding technologies, processes and equipment, along with the economic benefits and risks.  Due to the increasing cost of materials used to make electronic components, the electronics industry has been rapidly moving from high cost gold to significantly lower cost copper as a wire bonding material.  However, copper wire bonding has several process and reliability concerns due to its material properties.  Copper Wire Bonding book lays out the challenges involved in replacing gold with copper as a wire bond material, and includes the bonding process changes—bond force, electric flame off, current and ultrasonic energy optimization, and bonding tools and equipment changes for first and second bond formation.  In addition, the bond–pad metallurgies and the use of bare and palladium-coated copper wires on aluminum are presented, and gold, nickel and palladium surface finishes are discussed.  The book also discusses best practices and re...

  8. A natural analogue for copper waste canisters: The copper-uranium mineralised concretions in the Permian mudrocks of south Devon, United Kingdom

    International Nuclear Information System (INIS)

    mineralisation and alteration that can be related to the burial and diagenetic history of the Permian strata. The native copper mineralisation exhibits close temporal association with the formation of uraniferous and vanadiferous concretions (known as 'fish-eyes') in the same rocks. Petrographical relationships indicate that both the copper and the 'fish-eye' concretions formed during burial diagenesis but before the maximum compaction of the host mudstone and siltstone. The regional burial history Wessex Basin, indicates that the maximum compaction of the Permian strata would have been achieved by at least the end of the Lower Jurassic (possibly even in the Triassic). Therefore, the native copper mineralisation is older than 176 Ma. The native copper sheets display a complex sequence of alteration and subsequent mineral growth of minerals on their surfaces. The earliest alteration was to copper oxides - principally cuprite with minor tenorite, indicating a change to more oxidising groundwater conditions. The dissolution of native silver and the growth of fringes of copper arsenides followed this. Nickel arsenides and chalcocite, associated with the precipitation of uranium silicates occurred in the later stages of alteration. This suggests a return to a more reducing pore water environment. Again, petrographical relationships indicate that this alteration and subsequent mineralisation is geologically old (i.e. Lower Jurassic or older). Secondary malachite, intimately intergrown copper sulphate and copper oxides, copper chloride, copper-uranium arsenate and uranium vanadates have formed as late-stage alteration products of the native copper and earlier diagenetic cuprite, chalcocite, copper-nickel arsenide and uranium silicate alteration and mineralisation. This latest stage alteration is most probably attributable to near-surface weathering processes. Although the native copper is affected by corrosion, the study has shown that a significant proportion (30-80% of the original

  9. A natural analogue for copper waste canisters: The copper-uranium mineralised concretions in the Permian mudrocks of south Devon, United Kingdom

    Energy Technology Data Exchange (ETDEWEB)

    Milodowski, A.E.; Styles, M.T.; Hards, V.L. [Natural Environment Research Council (United Kingdom). British Geological Survey

    2000-08-01

    mineralisation and alteration that can be related to the burial and diagenetic history of the Permian strata. The native copper mineralisation exhibits close temporal association with the formation of uraniferous and vanadiferous concretions (known as 'fish-eyes') in the same rocks. Petrographical relationships indicate that both the copper and the 'fish-eye' concretions formed during burial diagenesis but before the maximum compaction of the host mudstone and siltstone. The regional burial history Wessex Basin, indicates that the maximum compaction of the Permian strata would have been achieved by at least the end of the Lower Jurassic (possibly even in the Triassic). Therefore, the native copper mineralisation is older than 176 Ma. The native copper sheets display a complex sequence of alteration and subsequent mineral growth of minerals on their surfaces. The earliest alteration was to copper oxides - principally cuprite with minor tenorite, indicating a change to more oxidising groundwater conditions. The dissolution of native silver and the growth of fringes of copper arsenides followed this. Nickel arsenides and chalcocite, associated with the precipitation of uranium silicates occurred in the later stages of alteration. This suggests a return to a more reducing pore water environment. Again, petrographical relationships indicate that this alteration and subsequent mineralisation is geologically old (i.e. Lower Jurassic or older). Secondary malachite, intimately intergrown copper sulphate and copper oxides, copper chloride, copper-uranium arsenate and uranium vanadates have formed as late-stage alteration products of the native copper and earlier diagenetic cuprite, chalcocite, copper-nickel arsenide and uranium silicate alteration and mineralisation. This latest stage alteration is most probably attributable to near-surface weathering processes. Although the native copper is affected by corrosion, the study has shown that a significant proportion (30

  10. Reduction of chromate and carotene-synthesizing activity of selenite-resistant mutants of the yeast Xanthophyllomyces dendrorhous (Phaffia rhodozyma

    Directory of Open Access Journals (Sweden)

    Grzàdka M.

    2009-08-01

    Full Text Available Aim. The yeast P. rhodozyma is a perspective microbial producer of carotenoid pigment astaxanthin with a high antioxidant power. The aim of the work was to study the ability of the selenite-resistant strains of this yeast to reduce chrome(VI compounds, as well as to analyze the relations between synthesis of carotenoids, resistance to selenite and chromate-reducing activity of P. rhodozyma. Methods. The yeast cells were grown at standard conditions for this species. The residual chromate content in cultural liquid was determined colorimetrically using diphenylcarbazide. The carotenoid content was determined after extraction of the pigments from the previously permeabilized cells by organic solvents. Results. The selected selenite-resistant mutants of the yeast P. rhodozyma revealed the different combinations of the phenotypes related with tolerance/sensitivity to chromate and selenite, as well as ability to reduce chromate. Conclusions. The obtained results give reasons for suggesting that pathways of detoxification of chromate and selenite by the yeast P. rhodozyma are different, although run through a common reductive type. The isolated mutant strains would be served as the useful models to study relations between homeostasis of Se and Cr oxyanions and biosynthesis of carotenes.

  11. Chromatic line-profile tomography to reveal exoplanetary atmospheres: application to HD 189733b

    Science.gov (United States)

    Borsa, F.; Rainer, M.; Poretti, E.

    2016-05-01

    Context. Transmission spectroscopy can be used to constrain the properties of exoplanetary atmospheres. During a transit, the light blocked from the atmosphere of the planet leaves an imprint in the light coming from the star. This has been shown for many exoplanets with both photometry and spectroscopy, using different analysis methods. Aims: We test chromatic line-profile tomography as a new tool to investigate exoplanetary atmospheres. The signal imprinted on the cross-correlation function (CCF) by a planet transiting its star is dependent on the planet-to-star radius ratio. We want to verify whether the precision reachable on the CCF obtained from a subset of the spectral orders of the HARPS spectrograph is high enough to determine the radius of a planet at different wavelengths. Methods: We analyze HARPS archival data of three transits of HD 189733b. We divide the HARPS spectral range into seven broadbands, calculating for each band the ratio between the area of the out-of-transit CCF and the area of the signal imprinted by the planet on it during the full part of the transit. We take into account the effect of the limb darkening using the theoretical coefficients of a linear law. Averaging the results of three different transits allows us to obtain a good-quality broadband transmission spectrum of HD 189733b with a greater precision than that of the chromatic Rossiter McLaughlin effect. Results: We proved that chromatic line-profile tomography is an interesting way to reveal broadband transmission spectra of exoplanets: our analysis of the atmosphere of HD 189733b is in agreement with other ground- and space-based observations. The independent analysis of different transits emphasizes the probability that stellar activity plays a role in the extracted transmission spectrum. Therefore, care should be taken when claiming that Rayleigh scattering is present in the atmosphere of exoplanets orbiting active stars using only one transit.

  12. A Light-Activated Olefin Metathesis Catalyst Equipped with a Chromatic Orthogonal Self-Destruct Function.

    Science.gov (United States)

    Sutar, Revannath L; Levin, Efrat; Butilkov, Danielle; Goldberg, Israel; Reany, Ofer; Lemcoff, N Gabriel

    2016-01-11

    A sulfur-chelated photolatent ruthenium olefin metathesis catalyst has been equipped with supersilyl protecting groups on the N-heterocyclic carbene ligand. The silyl groups function as an irreversible chromatic kill switch, thus decomposing the catalyst when it is irradiated with 254 nm UV light. Therefore, different types of olefin metathesis reactions may be started by irradiation with 350 nm UV light and prevented by irradiation with shorter wavelengths. The possibility to induce and impede catalysis just by using light of different frequencies opens the pathway for stereolithographic applications and novel light-guided chemical sequences. PMID:26586469

  13. New Categorifications of the Chromatic and the Dichromatic Polynomials for Graphs

    OpenAIRE

    Stosic, Marko

    2005-01-01

    In this paper, for each graph $G$, we def\\mbox{}ine a chain complex of graded modules over the ring of polynomials, whose graded Euler characteristic is equal to the chromatic polynomial of $G$. Furthermore, we def\\mbox{}ine a chain complex of doubly-graded modules, whose (doubly) graded Euler characteristic is equal to the dichromatic polynomial of $G$. Both constructions use Koszul complexes, and are similar to the new Khovanov-Rozansky categorif\\mbox{}ications of HOMFLYPT polynomial. We al...

  14. Oscillations of the Chromatic States and Accelerated Expansion of the Universe

    Directory of Open Access Journals (Sweden)

    Quznetsov G.

    2010-04-01

    Full Text Available It is known (Quznetsov G. Higgsless Glashow’s and quark-gluon theories and gravity without superstrings. Progress in Physics , 2009, v. 3, 32–40 that probabilities of point- like events are defined by some generalization of Dirac’s equation. One part of such generalized equation corresponds to the Dirac’s leptonic equation, and the other part corresponds to the Dirac’s quark equation. The quark part of this equation is invariant under the oscillations of chromatic states. And it turns out that these oscillations bend space-time so that at large distances the space expands with acceleration according to Hubble’s law.

  15. Oscillations of the Chromatic States and Accelerated Expansion of the Universe

    Directory of Open Access Journals (Sweden)

    Quznetsov G.

    2010-04-01

    Full Text Available It is known (Quznetsov G. Higgsless Glashow's and quark-gluon theories and gravity without superstrings. Progress in Physics, 2009, v.3, 32-40 that probabilities of pointlike events are defined by some generalization of Dirac's equation. One part of such generalized equation corresponds to the Dirac's leptonic equation, and the other part corresponds to the Dirac's quark equation. The quark part of this equation is invariant under the oscillations of chromatic states. And it turns out that these oscillations bend space-time so that at large distances the space expands with acceleration according to Hubble's law.

  16. Frequency-Domain Chromatic Dispersion Equalization Using Overlap-Add Methods in Coherent Optical System

    CERN Document Server

    Xu, Tianhua; Popov, Sergei; Forzati, Marco; Martensson, Jonas; Mussolin, Marco; Li, Jie; Wang, Ke; Zhang, Yimo; Friberg, Ari T

    2016-01-01

    The frequency domain equalizers (FDEs) employing two types of overlap-add zero-padding (OLA-ZP) methods are applied to compensate the chromatic dispersion in a 112-Gbit/s non-return-to-zero polarization division multiplexed quadrature phase shift keying (NRZ-PDM-QPSK) coherent optical transmission system. Simulation results demonstrate that the OLA-ZP methods can achieve the same acceptable performance as the overlap-save method. The required minimum overlap (or zero-padding) in the FDE is derived, and the optimum fast Fourier transform length to minimize the computational complexity is also analyzed.

  17. A Light-Activated Olefin Metathesis Catalyst Equipped with a Chromatic Orthogonal Self-Destruct Function.

    Science.gov (United States)

    Sutar, Revannath L; Levin, Efrat; Butilkov, Danielle; Goldberg, Israel; Reany, Ofer; Lemcoff, N Gabriel

    2016-01-11

    A sulfur-chelated photolatent ruthenium olefin metathesis catalyst has been equipped with supersilyl protecting groups on the N-heterocyclic carbene ligand. The silyl groups function as an irreversible chromatic kill switch, thus decomposing the catalyst when it is irradiated with 254 nm UV light. Therefore, different types of olefin metathesis reactions may be started by irradiation with 350 nm UV light and prevented by irradiation with shorter wavelengths. The possibility to induce and impede catalysis just by using light of different frequencies opens the pathway for stereolithographic applications and novel light-guided chemical sequences.

  18. Cloning and expression of plasmid genes encoding resistances to chromate and cobalt in Alcaligenes eutrophus.

    OpenAIRE

    Nies, A; Nies, D H; Silver, S

    1989-01-01

    Resistances to chromate and cobalt were cloned on a 30-kilobase-pair (kb) DNA region from the large Alcaligenes eutrophus plasmid pMOL28 into the broad-host-range mobilizable cosmid vector pVK102. A restriction nuclease map of the 30-kb region was generated. The resistances expressed from the hybrid plasmids after transfer back into A. eutrophus were inducible and conferred the same degree of resistance as the parent plasmid pMOL28. Resistances were expressed in metal-sensitive Alcaligenes st...

  19. Standard Specification for Copper-Aluminum-Silicon-Cobalt Alloy, Copper-Nickel-Silicon-Magnesium Alloy, Copper-Nickel-Silicon Alloy, Copper-Nickel-Aluminum-Magnesium Alloy, and Copper-Nickel-Tin Alloy Sheet and Strip

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2015-01-01

    Standard Specification for Copper-Aluminum-Silicon-Cobalt Alloy, Copper-Nickel-Silicon-Magnesium Alloy, Copper-Nickel-Silicon Alloy, Copper-Nickel-Aluminum-Magnesium Alloy, and Copper-Nickel-Tin Alloy Sheet and Strip

  20. Conjugative plasmid in Corynebacterium flaccumfaciens subsp. oortii that confers resistance to arsenite, arsenate, and antimony(III)

    Energy Technology Data Exchange (ETDEWEB)

    Hendrick, C.A.; Haskins, W.P.; Vidaver, A.K.

    1984-07-01

    Gene transfer systems for phytopathogenic corynebacteria have not been reported previously. In this paper a conjugative 46-megadalton plasmid (pDG101) found in Corynebacterium flaccumfaciens subsp. oorii CO101 is described that mediates resistance to arsenite, arsenate, and antimony(III). Transfer of the plasmid from CO101 to four other strains from the C. flaccumfaciens group occurred between cells immobilized on nitrocellulose filters or on agar surfaces. Transconjugant strains expressed the same levels of metal resistance as the donor strain and were able to act as donor strains in subsequent matings. The physical presence of the plasmid was detected by agarose gel electrophoresis. Arsenite-sensitive derivatives of the donor and transconjugant strains were obtained after heat treatment; these were cured of pDG101.

  1. Evaluation of Corrosion Behavior of Galvanized Steel Treated with Conventional Conversion Coatings and a Chromate-Free Organic Inhibitor

    Directory of Open Access Journals (Sweden)

    Laura A. Hernandez-Alvarado

    2012-01-01

    Full Text Available Conventional weight loss tests and both DC and AC electrochemical techniques were used to study if an organic inhibitor containing an alkanolamine salt of a polycarboxylic acid can substitute toxic coatings as chromating and certain phosphating procedures in the protection of galvanized steel. The electrolyte used was a 0.5 M aerated NaCl solution. All tests gave concordant results, indicating that the chromate-free organic inhibitor does protect galvanized steel in this environment, even though the provided protection was less than that of the chromate conversion coating. It was observed that, after a moderate initial attack, the corrosion rate diminishes due to the appearance and growth of passivating corrosion products layers, mainly constituted by zinc hydroxychloride (Zn5(OH8CI2⋅H2O and two varieties of zinc hydroxide, among other crystalline compounds.

  2. Treatment tests for ex situ removal of chromate, nitrate, and uranium (VI) from Hanford (100-HR-3) groundwater

    International Nuclear Information System (INIS)

    This report describes batch and anion exchange column laboratory-scale studies investigating ex situ methods to remove chromate (chromium [VI]), nitrate (NO3), and uranium (present as uranyl (uranium [VI]) carbonato anionic species) 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 (DOE-RL 1993). The goal of these tests was to determine the best method to remove selected contaminants to below the concentration of the project performance goals. The raw data and observations made during these tests can be found in the Westinghouse Hanford Company (WHC) laboratory notebooks (Beck 1992, Herting 1993). The method recommended for future study is anion exchange with Dowex 21K resin

  3. Dissociation of equilibrium points for color-discrimination and color-appearance mechanisms in incomplete chromatic adaptation.

    Science.gov (United States)

    Sato, Tomoharu; Nagai, Takehiro; Kuriki, Ichiro; Nakauchi, Shigeki

    2016-03-01

    We compared the color-discrimination thresholds and supra-threshold color differences (STCDs) obtained in complete chromatic adaptation (gray) and incomplete chromatic adaptation (red). The color-difference profiles were examined by evaluating the perceptual distances between various color pairs using maximum likelihood difference scaling. In the gray condition, the chromaticities corresponding with the smallest threshold and the largest color difference were almost identical. In contrast, in the red condition, they were dissociated. The peaks of the sensitivity functions derived from the color-discrimination thresholds and STCDs along the L-M axis were systematically different between the adaptation conditions. These results suggest that the color signals involved in color discrimination and STCD tasks are controlled by separate mechanisms with different characteristic properties.

  4. Treatment tests for ex situ removal of chromate, nitrate, and uranium (VI) from Hanford (100-HR-3) groundwater. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Beck, M.A.; Duncan, J.B.

    1993-11-15

    This report describes batch and anion exchange column laboratory-scale studies investigating ex situ methods to remove chromate (chromium [VI]), nitrate (NO{sub 3}), and uranium (present as uranyl (uranium [VI]) carbonato anionic species) 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 (DOE-RL 1993). The goal of these tests was to determine the best method to remove selected contaminants to below the concentration of the project performance goals. The raw data and observations made during these tests can be found in the Westinghouse Hanford Company (WHC) laboratory notebooks (Beck 1992, Herting 1993). The method recommended for future study is anion exchange with Dowex 21K resin.

  5. Possible Roles of Plant Sulfurtransferases in Detoxification of Cyanide, Reactive Oxygen Species, Selected Heavy Metals and Arsenate

    Directory of Open Access Journals (Sweden)

    Parvin Most

    2015-01-01

    Full Text Available Plants and animals have evolved various potential mechanisms to surmount the adverse effects of heavy metal toxicity. Plants possess low molecular weight compounds containing sulfhydryl groups (-SH that actively react with toxic metals. For instance, glutathione (γ-Glu-Cys-Gly is a sulfur-containing tripeptide thiol and a substrate of cysteine-rich phytochelatins (γ-Glu-Cys2–11-Gly (PCs. Phytochelatins react with heavy metal ions by glutathione S-transferase in the cytosol and afterwards they are sequestered into the vacuole for degradation. Furthermore, heavy metals induce reactive oxygen species (ROS, which directly or indirectly influence metabolic processes. Reduced glutathione (GSH attributes as an antioxidant and participates to control ROS during stress. Maintenance of the GSH/GSSG ratio is important for cellular redox balance, which is crucial for the survival of the plants. In this context, sulfurtransferases (Str, also called rhodaneses, comprise a group of enzymes widely distributed in all phyla, paving the way for the transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors, at least in vitro. The best characterized in vitro reaction is the transfer of a sulfane sulfur atom from thiosulfate to cyanide, leading to the formation of sulfite and thiocyanate. Plants as well as other organisms have multi-protein families (MPF of Str. Despite the presence of Str activities in many living organisms, their physiological role has not been clarified unambiguously. In mammals, these proteins are involved in the elimination of cyanide released from cyanogenic compounds. However, their ubiquity suggests additional physiological functions. Furthermore, it is speculated that a member of the Str family acts as arsenate reductase (AR and is involved in arsenate detoxification. In summary, the role of Str in detoxification processes is still not well understood but seems to be a major function in the organism.

  6. Estimating and controlling chromatic aberration losses for two-junction, two-terminal devices in refractive concentrator systems

    Energy Technology Data Exchange (ETDEWEB)

    Kurtz, S.R. [National Renewable Energy Lab., Golden, CO (United States); O`Neill, M.J. [ENTECH, Inc., Keller, TX (United States)

    1996-05-01

    Although previous studies have measured and calculated chromatic aberration losses and proposed methods for reducing these by modifying the optics, significant work remains to be done toward understanding how to quantity the losses and how various parameters affect this loss. This paper presents an analytical definition and calculation method for chromatic aberration losses. The effects of sheet resistance of the midlayers of the cell, total irradiance, incident spectrum, cell width, and diode quality factor are studied. A method for measuring the midlayer resistance in finished sells is described.

  7. Experimental and numerical analysis of the chromatic dispersion dependence upon the actual profile of small core microstructured fibres

    CERN Document Server

    Labonté, Laurent; Pagnoux, Dominique; Louradour, Frédéric; Restoin, Christine; Mélin, Gilles; Burov, Ekatarina

    2010-01-01

    The chromatic dispersion curve of the fundamental mode in small core microstructured fibres (SCMF) is both calculated using a Finite Element Method (FEM) and measured with a low coherence interferometric method. The great sensitivity of the chromatic dispersion to variations of the geometrical parameters of SCMFs (the pitch and the diameter) is pointed out. An excellent agreement is obtained between the numerical and the experimental results over a half micrometer spectral bandwidth [1.1 $\\mu$m-1.6 $\\mu$m].

  8. Use of a spectrally tunable source to explore improvement in chromatic contrast for illumination of tissues

    Science.gov (United States)

    Litorja, Maritoni; Ecker, Ben

    2010-02-01

    Human vision by a clinical practitioner is often the first disease detection tool. Illumination for such procedures as endoscopy use broadband white light, with luminance level being the only control available. The use of staining dyes for contrast improvement have shown limited adoption due to the additional steps needed and small number of approved dyes for in vivo use. Here we explore the control of the illuminant spectral distribution to improve chromatic contrast without the use of dyes. The computational steps used in converting spectral data to RGB and use of the CIELAB chromatic and luminance contrast metric as criteria in determining the appropriate lighting spectral distribution will be discussed. The skin on the back of the hand and the skin section over a vein are used as examples of tissue features to be contrasted. A 3-wavelelength LED lamp and an incandescent lamp with the yellow spectral region filtered out are shown as examples that spectrally-shaped illumination can enhance visual contrast.

  9. Laser weld process monitoring and control using chromatic filtering of thermal radiation from a weld pool

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Cheol Jung; Kim, Min Suk; Baik, Sung Hoon; Chung, Chin Man

    2000-06-01

    The application of high power Nd: YAG lasers for precision welding in industry has been growing quite fast these days in diverse areas such as the automobile, the electronics and the aerospace industries. These diverse applications also require the new developments for the precise control and the reliable process monitoring. Due to the hostile environment in laser welding, a remote monitoring is required. The present development relates in general to weld process monitoring techniques, and more particularly to improved methods and apparatus for real-time monitoring of thermal radiation of a weld pool to monitor a size variation and a focus shift of the weld pool for weld process control, utilizing the chromatic aberration of focusing lens or lenses. The monitoring technique of the size variation and the focus shift of a weld pool is developed by using the chromatic filtering of the thermal radiation from a weld pool. The monitoring of weld pool size variation can also be used to monitor the weld depth in a laser welding. Furthermore, the monitoring of the size variation of a weld pool is independent of the focus shift of a weld pool and the monitoring of the focus shift of a weld pool is independent of the size variation of a weld pool.

  10. Ponceau 6R dye decoloration and chromate reduction simultaneously in acid medium

    Directory of Open Access Journals (Sweden)

    Seddique M. Ahmed

    2015-07-01

    Full Text Available The degradation efficiency and kinetic degradation reaction of Ponceau 6R dye using potassium chromate have been investigated under various experimental conditions: different concentrations of H2SO4 and temperatures. The immediate change of the red coloration (λmax = 518 nm to colorless was observed after addition of inorganic oxidizing agent (K2CrO4 into the protonated form of Ponceau 6R dye after 48 h. This observation could be attributed to the highest oxidized form of this dye obtained (the quinoid one, which undergoes a hydrolysis reaction to produce p-hydroquinone (H2Q by a mechanism similar to Schiff-base hydrolysis. The cationic form of this matrix is a crucial feature for the hydrolysis process. A kinetic model for oxidation of Ponceau 6R by the combination of chromate was developed based on experimental results. The observed kinetic reaction coefficient was determined and correlated as a function of UV spectral intensity of Ponceau 6R at 518 nm. The degradation rate follows pseudo-first order kinetics with respect to dye concentration.

  11. Structural and magnetic studies of the Zn-substituted magnesium ferrite chromate

    Science.gov (United States)

    Gismelseed, A. M.; Mohammed, K. A.; Al-Rawas, A. D.; Yousif, A. A.; Widatallah, H. M.; Elzain, M. E.

    2014-04-01

    The mixed zinc-magnesium ferrite chromate with composition Mg1-xZnxFeCrO4 (0.0 ≤ x ≤ 1.0) prepared by the conventional solid state double sintering ceramic technique were characterized using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Mössbauer Spectroscopy (MS). The analysis of the X-ray pattern reveal that the samples crystalize in a single-phase cubic spinel structure and the lattice parameter increases linearly with increasing the Zn content. The SEM micrographs showed aggregates of stacked grains of about (0.2 ˜ 1.5 μm) in diameter. The 78 K Mössbauer spectrum of pure magnesium chromate shows an ordered magnetic structure with well resolved tetrahedral and octahedral sites. As Zn substitutes for Mg, the 78 K spectra started to show the presence of a paramagnetic component superimposed on broadened magnetic sextets. This behavior is attributed to the presence of superparamagnetic domains in the samples which will be discussed based on the weakening of A-B exchange interaction in ferrite lattice due to replacement of Fe3+ ions in tetrahedral sites by Zn2+ ions.

  12. Laser weld process monitoring and control using chromatic filtering of thermal radiation from a weld pool

    International Nuclear Information System (INIS)

    The application of high power Nd: YAG lasers for precision welding in industry has been growing quite fast these days in diverse areas such as the automobile, the electronics and the aerospace industries. These diverse applications also require the new developments for the precise control and the reliable process monitoring. Due to the hostile environment in laser welding, a remote monitoring is required. The present development relates in general to weld process monitoring techniques, and more particularly to improved methods and apparatus for real-time monitoring of thermal radiation of a weld pool to monitor a size variation and a focus shift of the weld pool for weld process control, utilizing the chromatic aberration of focusing lens or lenses. The monitoring technique of the size variation and the focus shift of a weld pool is developed by using the chromatic filtering of the thermal radiation from a weld pool. The monitoring of weld pool size variation can also be used to monitor the weld depth in a laser welding. Furthermore, the monitoring of the size variation of a weld pool is independent of the focus shift of a weld pool and the monitoring of the focus shift of a weld pool is independent of the size variation of a weld pool

  13. Correction of axial chromatic aberrations in confocal Raman microspectroscopic measurements of a single microbial spore.

    Science.gov (United States)

    Lasch, Peter; Hermelink, Antje; Naumann, Dieter

    2009-06-01

    Herein we describe a strategy for correcting the longitudinal or axial component of chromatic aberration in confocal Raman microspectroscopy. The method is based on measuring a vertical series of confocal Raman sections of samples by a high numerical aperture Raman microscope. Using the known characteristics of the wavelength-dependent focal shift of the optical system, the Raman intensities can be corrected to allow the rearrangement of Raman data from different focal planes. In the present study the computational correction routine was applied to an experimental data set of 4-dimensional (xyz spatial and the spectral dimension) confocal Raman spectra collected from single spores of Bacillus cereus. After correcting the axial component of the chromatic aberration, univariate and multivariate spectral parameters were obtained and used in the following for 3D segmentation and volume rendering on the basis of the structural and compositional information contained in the Raman spectra of the spore. Using univariate Raman intensities from defined functional group frequencies or k-means cluster membership values as a multivariate parameter for volume rendering, we demonstrate a high degree of correlation between confocal Raman microspectroscopy and the spores' morphology. In this paper we will also present cluster mean spectra which will be discussed in light of the presence of proteins and Ca-DPA, a calcium chelate of dipicolinic acid in the spore. PMID:19475143

  14. Single bunch transverse instability in a circular accelerator with chromaticity and space charge

    International Nuclear Information System (INIS)

    The transverse instability of a bunch in a circular accelerator is elaborated in this paper. A new tree-modes model is proposed and developed to describe the most unstable modes of the bunch. This simple and flexible model includes chromaticity and space charge, and can be used with any bunch and wake forms. The dispersion equation for the bunch eigentunes is obtained in form of a third-order algebraic equation. The known head-tail and TMCI modes appear as the limiting cases which are distinctly bounded at zero chromaticity only. It is shown that the instability parameters depend only slightly on the bunch model but they are rather sensitive to the wake shape. In particular, space charge effects are investigated in the paper and it is shown that their influence depends on sign of wake field enhancing the bunch stability if the wake is negative. The resistive wall wake is considered in detail including a comparison of single and collective effects. A comparison of the results with earlier publications is carried out

  15. Study of Gravitational Lens Chromaticity from Ground-based Narrow Band Photometry

    CERN Document Server

    Mosquera, Ana M; Mediavilla, Evencio; Kochanek, Christopher S

    2010-01-01

    We present observations of wavelength-dependent flux ratios for 4 gravitational lens systems (SDSS~J1650+4251, HE~0435$-$1223, FBQ 0951+2635, and Q~0142$-$100) obtained with the Nordic Optical telescope (NOT). The use of narrow band photometry, as well as the excellent seeing conditions during the observations, allow us to set good baselines to study their chromatic behavior. For SDSS~J1650+4251 we determine the extinction curve of the dust in the $z_L=0.58$ lens galaxy, and find that the 2175 \\AA \\ feature is absent. In the case of HE~0435$-$1223 we clearly detect chromatic microlensing. This allows us to estimate the wavelength dependent size of the accretion disk. We found an R-band disk size of $r^{R}_s=13\\pm5$ light days for a linear prior on $r^{R}_s$ and of $r^{R}_s=7\\pm6$ light days for a logarithmic prior. For a power law size-wavelength scaling of $r_s\\propto\\lambda^{p}$, we were able to constrain the value of the exponent to $p=1.3\\pm0.3$ for both $r^{R}_s$ priors, which is in agreement with the te...

  16. The reduction of chromate ions by Fe(II layered hydroxides

    Directory of Open Access Journals (Sweden)

    S. Loyaux-Lawniczak

    1999-01-01

    Full Text Available The reduction of chromate ions by Fe(OH2 and the iron (II-iron (III hydroxysulphate green rust, GR(SO42-, was studied to evaluate whether such synthetic layered hydroxides and the corresponding natural green rust mineral could be involved in the natural attenuation of contaminated environments. The resulting Cr (III bearing phases, which would govern the subsequent behaviour of chromium, were clearly characterised. Both compounds proved to be very reactive and oxidised instantaneously while chromate ions were reduced to Cr (III as evidenced by X-ray photoelectron spectroscopy. Mass balance (ICP-AES demonstrated that the Fe/Cr ratio inside the solid end product was equal to the initial Fe/Cr ratio. The solid phases, analysed by X-ray diffraction, Raman and Mossbauer spectroscopies were identified as Cr-substituted poorly crystallised iron (III oxyhydroxides in both cases, more precisely δ-FeOOH when starting with Fe(OH2 and ferrihydrite when starting with GR(SO42-.

  17. FORMATION OF CHROMATE CONVERSION COATINGS ON ALUMINUM AND ITS ALLOYS: AN IN SITU XANES STUDY.

    Energy Technology Data Exchange (ETDEWEB)

    SASAKI,K.; ISAACS,H.S.; JAFFCOATE,C.S.; BUCHHAIT,R.; LEGAT,V.; LEE,H.; SRINIVASAMURTHI,V.

    2001-09-02

    We used in situ X-ray adsorption near-edge structure (XANES) to investigate the formation of chromate conversion coatings on pure Al, commercial Al alloys (AA 1100, AA2024, and AA7075), and a series of binary Al-Cu alloys. The method employed a new electrochemical cell that can determine the ratio of hexavalent chromium (Cr(VI)) to total chromium (Cr(total)) speciation in conversion coatings as a function of exposure time to a chromate solution. The spectra showed that the initial Cr(VI)/Cr(total) ratios are greater than later ones for pure Al and AA1100, but not for AA2024 and AA7075. Measurements with Al-Cu alloys demonstrated that the difference observed in AA2024 and AA7075 may not be due to Cu alloying. The proportion of Cr(VI) in the coatings becomes approximately constant after 180 s of exposure for all the specimens examined even though the coatings continue to grow.

  18. Recycler Chromaticities and End Shims for NOvA at Fermilab

    CERN Document Server

    Xiao, M

    2013-01-01

    In era of NOvA operation, it is planned to slip-stack six on six Booster proton batches in the Recycler ring for a total intensity of 5 1013 protons/cycle. During the slip-stacking, the chromaticities are required to be jumped from (-2,-2) to (-20,-20). However, they can only be adjusted to (-12,-12) from (-2,-2) using existing 2 families of powered sextupoles. On the other hand, the presently designed Recycler lattice for Nova replaces the 30 straight section with 8 D-D half FODO cells . We use 3 quads in a half-cell to obtain the working point under the limit of the feasible quad strength, and the maximum beta-function in this section cannot be less than 80 m. In this paper, we re-designed the end shims of the permanent magnets in the ring lattice with appropriate quadrupole and sextupole components to meet both chromaticity and tune requirements. We are able to use 2 quads in a half cell in RR30 straight section within feasible quad strength. The maximum beta-functions are also lowered to around 55 m. The ...

  19. Chromatic Mechanical Response in 2-D Layered Transition Metal Dichalcogenide (TMDs) based Nanocomposites

    Science.gov (United States)

    Rahneshin, Vahid; Khosravi, Farhad; Ziolkowska, Dominika A.; Jasinski, Jacek B.; Panchapakesan, Balaji

    2016-10-01

    The ability to convert photons of different wavelengths directly into mechanical motion is of significant interest in many energy conversion and reconfigurable technologies. Here, using few layer 2H-MoS2 nanosheets, layer by layer process of nanocomposite fabrication, and strain engineering, we demonstrate a reversible and chromatic mechanical response in MoS2-nanocomposites between 405 nm to 808 nm with large stress release. The chromatic mechanical response originates from the d orbitals and is related to the strength of the direct exciton resonance A and B of the few layer 2H-MoS2 affecting optical absorption and subsequent mechanical response of the nanocomposite. Applying uniaxial tensile strains to the semiconducting few-layer 2H-MoS2 crystals in the nanocomposite resulted in spatially varying energy levels inside the nanocomposite that enhanced the broadband optical absorption up to 2.3 eV and subsequent mechanical response. The unique photomechanical response in 2H-MoS2 based nanocomposites is a result of the rich d electron physics not available to nanocomposites based on sp bonded graphene and carbon nanotubes, as well as nanocomposite based on metallic nanoparticles. The reversible strain dependent optical absorption suggest applications in broad range of energy conversion technologies that is not achievable using conventional thin film semiconductors.

  20. Reduction of chromatic aberration influences in vertical scanning white-light interferometry

    International Nuclear Information System (INIS)

    Vertical scanning white-light interferometry (SWLI) is a well-established method that is widely used in high precision surface topography measurement. However, SWLI results show characteristic slope-dependent errors due to dispersion effects and lateral chromatic aberrations of the optical imaging system. In this paper, we present methods to characterize these systematic errors related to dispersion and lateral colour. Lateral colour leads to field-dependent systematic discrepancies of the topography data obtained from the envelope position of a low-coherence interference signal and the data resulting from its interference phase. Hence, an erroneous fringe order obtained from the envelope position leads to a 2π phase jump and thus to a so-called ghost step in the measured topography. Our first approach to solve this problem is based on the measurement of a surface standard of well-known geometry. By comparison of measurement results related to the envelope position and the phase of SWLI signals, the systematic error is estimated and a numerical error compensation method is proposed. Both experimental and simulation results confirm the validity of this numerical method. In addition, using an improved design of a white-light Michelson interferometer we demonstrate experimentally that lateral chromatic aberrations and dispersion influences can be reduced also in a physical way. In this context, a conventional long working distance microscope objective is used which was not originally designed for a Michelson interference microscope. (paper)

  1. Chromaticity decay due to superconducting dipoles on the injection plateau of the Large Hadron Collider

    CERN Document Server

    Aquilina, N; Sammut, N; Strzeclzyk, M; Todesco, E

    2012-01-01

    It is well known that in a superconducting accelerator a significant chromaticity drift can be induced by the decay of the sextupolar component of the main dipoles. In this paper we give a brief overview of what was expected for the Large Hadron Collider on the grounds of magnetic measurements of individual dipoles carried out during the production. According to this analysis, the decay time constants were of the order of 200 s: since the injection in the LHC starts at least 30 minutes after the magnets are at constant current, the dynamic correction of this effect was not considered to be necessary. The first beam measurements of chromaticity showed significant decay even after few hours. For this reason, a dynamic correction of decay on the injection plateau was implemented based on beam measurements. This means that during the injection plateau the sextupole correctors are powered with a varying current to cancel out the decay of the dipoles. This strategy has been implemented successfully. A similar pheno...

  2. Jiangxi Copper Plans to Increase its Refined Copper Output

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>According to news published on March 30th, China’s largest copper producer--Jiangxi Copper alleged in its 2010 Financial Report Statement that it plans to improve its output of refined copper by 4.4% in 2011, to increase from 900,000 tonnes last year to 940,000 tons.

  3. Chinese Copper Manufacturers Expand Overseas

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>In 2012,China’s apparent copper consumption reached 8.84 million tons,accounting for 43%of the global total demand.Spurred by strong demand,China’s copper smelting capacity roars with annual average growth in domestic copper smelting capacity reaching approx-

  4. Fabrication and Characterization of Metallic Copper and Copper Oxide Nanoflowers

    Directory of Open Access Journals (Sweden)

    *H. S. Virk

    2011-12-01

    Full Text Available Copper nanoflowers have been fabricated using two different techniques; electro-deposition of copper in polymer and anodic alumina templates, and cytyltrimethal ammonium bromide (CTAB-assisted hydrothermal method. Scanning Electron Microscope (SEM images record some interesting morphologies of metallic copper nanoflowers. Field Emission Scanning Electron Microscope (FESEM has been used to determine morphology and composition of copper oxide nanoflowers. X-ray diffraction (XRD pattern reveals the monoclinic phase of CuO in the crystallographic structure of copper oxide nanoflowers. There is an element of random artistic design of nature, rather than science, in exotic patterns of nanoflowers fabricated in our laboratory.

  5. Copper and Copper Proteins in Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Sergio Montes

    2014-01-01

    Full Text Available Copper is a transition metal that has been linked to pathological and beneficial effects in neurodegenerative diseases. In Parkinson’s disease, free copper is related to increased oxidative stress, alpha-synuclein oligomerization, and Lewy body formation. Decreased copper along with increased iron has been found in substantia nigra and caudate nucleus of Parkinson’s disease patients. Copper influences iron content in the brain through ferroxidase ceruloplasmin activity; therefore decreased protein-bound copper in brain may enhance iron accumulation and the associated oxidative stress. The function of other copper-binding proteins such as Cu/Zn-SOD and metallothioneins is also beneficial to prevent neurodegeneration. Copper may regulate neurotransmission since it is released after neuronal stimulus and the metal is able to modulate the function of NMDA and GABA A receptors. Some of the proteins involved in copper transport are the transporters CTR1, ATP7A, and ATP7B and the chaperone ATOX1. There is limited information about the role of those biomolecules in the pathophysiology of Parkinson’s disease; for instance, it is known that CTR1 is decreased in substantia nigra pars compacta in Parkinson’s disease and that a mutation in ATP7B could be associated with Parkinson’s disease. Regarding copper-related therapies, copper supplementation can represent a plausible alternative, while copper chelation may even aggravate the pathology.

  6. Industrial experiment of copper electrolyte purification by copper arsenite

    Institute of Scientific and Technical Information of China (English)

    ZHENG Ya-jie; XIAO Fa-xin; WANG Yong; LI Chun-hua; XU Wei; JIAN Hong-sheng; MA Yut-ian

    2008-01-01

    Copper electrolyte was purified by copper arsenite that was prepared with As2O3. And electrolysis experiments of purified electrolyte were carried out at 235 and 305 A/m2, respectively. The results show that the yield of copper arsenite is up to 98.64% when the molar ratio of Cu to As is 1.5 in the preparation of copper arsenite. The removal rates of Sb and Bi reach 74.11% and 65.60% respectively after copper arsenite is added in electrolyte. The concentrations of As, Sb and Bi in electrolyte nearly remain constant during electrolysis of 13 d. The appearances of cathode copper obtained at 235 and 305 A/m2 are slippery and even, and the qualification rate is 100% according to the Chinese standard of high-pure cathode copper(GB/T467-97).

  7. Structure and function of ferricyanide in the formation of chromate conversion coatings on aluminum aircraft alloy

    Energy Technology Data Exchange (ETDEWEB)

    Xia, L.; McCreery, R.L.

    1999-10-01

    Raman and infrared spectroscopy were used to determine the structure of Fe(CN){sup {minus}3}{sub 6} and its reaction products in chromate conversion coatings (CCCs) on AA 2024-T3 aluminum aircraft alloy. In addition, Raman spectroscopy was used to monitor CCC growth rates and their dependence on coating bath composition. The IR and Raman spectra of the air-dried CCC corresponded to those of Berlin green, a Fe{sup +3}-CN-FE{sup +3} polymer, and Fe(CN){sub 6}{sup {minus}3} physisorbed on Cr(OH){sub 3}. No other cyano-containing products were observed. When Fe(CN){sub 6}{sup {minus}3} was excluded from the coating bath, CCC formation rate greatly decreased. In addition, it was observed that Fe(CN){sub 6}{sup {minus}3} could rapidly oxidize AA 2024-T3, and Fe(CN){sub 6}{sup {minus}4} rapidly reduced Cr(VI) in bath conditions. These results indicate a redox mediation action for Fe(CN){sub 6}{sup {minus}3/{minus}4}, which greatly increases the reduction of Cr(VI) to Cr(III) by the alloy. This process is normally quite slow, and redox mediation by Fe(CN){sub 6}{sup {minus}3} is critical to CCC formation. IrCl{sub 6}{sup {minus}3}/{sup {minus}2} could substitute for Fe(CN){sub 6}{sup {minus}3/{minus}4} to produce a chromate film with properties very similar to a conventional CCC. The results establish redox mediation as the mechanism of acceleration of CCC formation, but provide no evidence for any additional role of Fe(CN){sub 6}{sup {minus}3/{minus}4} to produce a chromate film with properties very similar to a conventional CCC. The results establish redox mediation as the mechanism of acceleration of CCC formation, but provide no evidence for any additional role of Fe(CN){sub 6}{sup {minus}3/{minus}4} in corrosion protection.

  8. Coping with copper

    DEFF Research Database (Denmark)

    Nunes, Ines Marques; Jacquiod, Samuel Jehan Auguste; Brejnrod, Asker Daniel;

    2016-01-01

    Copper has been intensively used in industry and agriculture since mid-18(th) century and is currently accumulating in soils. We investigated the diversity of potential active bacteria by 16S rRNA gene transcript amplicon sequencing in a temperate grassland soil subjected to century-long exposure...

  9. Creative Copper Crests

    Science.gov (United States)

    Knab, Thomas

    2011-01-01

    In this article, the author discusses how to create an art activity that would link the computer-created business cards of fourth-grade students with an upcoming school-wide medieval event. Creating family crests from copper foil would be a great connection, since they, like business cards, are an individual's way to identify themselves to others.…

  10. Chromatic aberration and the roles of double-opponent and color-luminance neurons in color vision

    NARCIS (Netherlands)

    Vladusich, Tony

    2007-01-01

    How does the visual cortex encode color? I summarize a theory in which cortical double-opponent color neurons perform a role in color constancy and a complementary set of color-luminance neurons function to selectively correct for color fringes induced by chromatic aberration in the eye. The theory

  11. Hypoxia targeting copper complexes

    International Nuclear Information System (INIS)

    The importance and incidence of tumour hypoxia, its measurement and current treatments available, including pharmacological and radiopharmacological methods of targeting hypoxia, are discussed. A variety of in vitro and in vivo methods for imposing hypoxia have been developed and are reviewed. Copper, its chemistry, biochemistry and radiochemistry, the potential for use of copper radionuclides and its use to date in this field is considered with particular reference to the thiosemicarbazones. Their biological activity, metal chelation, in vitro and in vivo studies of their radiocopper complexes and the potential for their use as hypoxia targeting radiopharmaceuticals is described. The reduction of the copper(II) complex to copper(l), its pivotal importance in their biological behaviour, and the potential for manipulation of this to effect hypoxia selectivity are described. An in vitro method for assessing the hypoxia selectivity of radiopharmaceuticals is reported. The rapid deoxygenation and high viability of a mammalian cell culture in this system is discussed and factors which may affect the cellular uptake of a radiopharmaceutical are described. The design, synthesis and complexation with copper and radiocopper of a range of bis(thiosemicarbazones) is reported. Synthesis of these compounds is simple giving high yields of pure products. The characteristics of the radiocopper complexes (64Cu) including lipophilicity and redox activity are reported (reduction potentials in the range -0.314 - -0.590 V). High cellular uptakes of the radiocopper complexes of the ligands, in hypoxic and normoxic EMT6 and CHO320 cells, were observed. Extremes of selectivity are shown ranging from the hypoxia selective 64Cu(II)ATSM to normoxic cell selective 64Cu(II)GTS. The selectivities observed are compared with the physico chemical characteristics of the complexes. A good correlation exists between selectivity of the complex and its Cu(II)/Cu(I) reduction potential, with hypoxia

  12. Hypoxia targeting copper complexes

    Energy Technology Data Exchange (ETDEWEB)

    Dearling, J.L

    1998-11-01

    The importance and incidence of tumour hypoxia, its measurement and current treatments available, including pharmacological and radiopharmacological methods of targeting hypoxia, are discussed. A variety of in vitro and in vivo methods for imposing hypoxia have been developed and are reviewed. Copper, its chemistry, biochemistry and radiochemistry, the potential for use of copper radionuclides and its use to date in this field is considered with particular reference to the thiosemicarbazones. Their biological activity, metal chelation, in vitro and in vivo studies of their radiocopper complexes and the potential for their use as hypoxia targeting radiopharmaceuticals is described. The reduction of the copper(II) complex to copper(l), its pivotal importance in their biological behaviour, and the potential for manipulation of this to effect hypoxia selectivity are described. An in vitro method for assessing the hypoxia selectivity of radiopharmaceuticals is reported. The rapid deoxygenation and high viability of a mammalian cell culture in this system is discussed and factors which may affect the cellular uptake of a radiopharmaceutical are described. The design, synthesis and complexation with copper and radiocopper of a range of bis(thiosemicarbazones) is reported. Synthesis of these compounds is simple giving high yields of pure products. The characteristics of the radiocopper complexes ({sup 64}Cu) including lipophilicity and redox activity are reported (reduction potentials in the range -0.314 - -0.590 V). High cellular uptakes of the radiocopper complexes of the ligands, in hypoxic and normoxic EMT6 and CHO320 cells, were observed. Extremes of selectivity are shown ranging from the hypoxia selective {sup 64}Cu(II)ATSM to normoxic cell selective {sup 64}Cu(II)GTS. The selectivities observed are compared with the physico chemical characteristics of the complexes. A good correlation exists between selectivity of the complex and its Cu(II)/Cu(I) reduction potential

  13. Presenilin promotes dietary copper uptake.

    Directory of Open Access Journals (Sweden)

    Adam Southon

    Full Text Available Dietary copper is essential for multicellular organisms. Copper is redox active and required as a cofactor for enzymes such as the antioxidant Superoxide Dismutase 1 (SOD1. Copper dyshomeostasis has been implicated in Alzheimer's disease. Mutations in the presenilin genes encoding PS1 and PS2 are major causes of early-onset familial Alzheimer's disease. PS1 and PS2 are required for efficient copper uptake in mammalian systems. Here we demonstrate a conserved role for presenilin in dietary copper uptake in the fly Drosophila melanogaster. Ubiquitous RNA interference-mediated knockdown of the single Drosophila presenilin (PSN gene is lethal. However, PSN knockdown in the midgut produces viable flies. These flies have reduced copper levels and are more tolerant to excess dietary copper. Expression of a copper-responsive EYFP construct was also lower in the midgut of these larvae, indicative of reduced dietary copper uptake. SOD activity was reduced by midgut PSN knockdown, and these flies were sensitive to the superoxide-inducing chemical paraquat. These data support presenilin being needed for dietary copper uptake in the gut and so impacting on SOD activity and tolerance to oxidative stress. These results are consistent with previous studies of mammalian presenilins, supporting a conserved role for these proteins in mediating copper uptake.

  14. Copper uptake across rainbow trout gills: mechanisms of apical entry

    DEFF Research Database (Denmark)

    Grosell, Martin Hautopp; Wood, C. M.

    2002-01-01

    Copper, Homeostasis, sodium uptake, copper/sodium interactions, gill, rainbow trout, Oncorhynchus mykiss......Copper, Homeostasis, sodium uptake, copper/sodium interactions, gill, rainbow trout, Oncorhynchus mykiss...

  15. Cone photoreceptor sensitivities and unique hue chromatic responses: correlation and causation imply the physiological basis of unique hues.

    Directory of Open Access Journals (Sweden)

    Ralph W Pridmore

    Full Text Available This paper relates major functions at the start and end of the color vision process. The process starts with three cone photoreceptors transducing light into electrical responses. Cone sensitivities were once expected to be Red Green Blue color matching functions (to mix colors but microspectrometry proved otherwise: they instead peak in yellowish, greenish, and blueish hues. These physiological functions are an enigma, unmatched with any set of psychophysical (behavioral functions. The end-result of the visual process is color sensation, whose essential percepts are unique (or pure hues red, yellow, green, blue. Unique hues cannot be described by other hues, but can describe all other hues, e.g., that hue is reddish-blue. They are carried by four opponent chromatic response curves but the literature does not specify whether each curve represents a range of hues or only one hue (a unique over its wavelength range. Here the latter is demonstrated, confirming that opponent chromatic responses define, and may be termed, unique hue chromatic responses. These psychophysical functions also are an enigma, unmatched with any physiological functions or basis. Here both enigmas are solved by demonstrating the three cone sensitivity curves and the three spectral chromatic response curves are almost identical sets (Pearson correlation coefficients r from 0.95-1.0 in peak wavelengths, curve shapes, math functions, and curve crossover wavelengths, though previously unrecognized due to presentation of curves in different formats, e.g., log, linear. (Red chromatic response curve is largely nonspectral and thus derives from two cones. Close correlation combined with deterministic causation implies cones are the physiological basis of unique hues. This match of three physiological and three psychophysical functions is unique in color vision.

  16. White Organic Light-Emitting Diodes with fine chromaticity tuning via ultrathin layer position shifting

    CERN Document Server

    Choukri, H; Forget, S; Chenais, S; Castex, M C; Ades, D; Siove, A; Geffroy, B; Choukri, Hakim; Fischer, Alexis; Forget, Sebastien; Chenais, Sebastien; Castex, Marie-Claude; Ades, Dominique; Siove, Alain; Geffroy, Bernard

    2006-01-01

    Non-doped white organic light-emitting diodes using an ultrathin yellow-emitting layer of rubrene (5,6,11,12-tetraphenylnaphtacene) inserted on either side of the interface between a hole-transporting NPB (4,4'-bis[N-(1-naphtyl)-N-phenylamino]biphenyl) layer and a blue-emitting DPVBi (4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl) layer are described. Both the thickness and the position of the rubrene layer allow fine chromaticity tuning from deep-blue to pure-yellow via bright-white with CIE coordinates (x= 0.33, y= 0.32), a external quantum efficiency of 1.9%, and a color rendering index of 70. Such a structure also provides an accurate sensing tool to measure the exciton diffusion length in both DPVBi and NPB (8.7 and 4.9 nm respectively).

  17. Accurate control of chromaticity and spectra by feedback phosphor-coating.

    Science.gov (United States)

    Wang, Mei-Tan; Huang, Jung-Min

    2015-05-01

    The chromaticity coordinates and spectra of phosphor-converted LEDs are demonstrated to be well controlled in this study. Through the feedback coating method of stacked yellow, green, and red phosphor layers, the color rendering index (CRI), correlated color temperature (CCT), and spectra are determined to match precisely the desired target. In addition, the reabsorption effect is strongly influenced by the order of stacked phosphor layers and the selected excitation wavelength of phosphors. The degree of reabsorption will modify the original spectra and cause a mismatch between the experimental measurement and the simulation based on the linear superposition of blue light and phosphor-emitted light. This feedback coating method offers an easy approach towards optimized spectra, which can offer the highest luminous efficacy of radiation with excellent color-rendering properties. PMID:25969251

  18. Engineering chromatic dispersion and effective nonlinearity in a dual-slot waveguide.

    Science.gov (United States)

    Liu, Yan; Yan, Jing; Han, Genquan

    2014-09-20

    In this paper, we propose a new dual slot based on rib-like structure, which exhibits a flat and near-zero dispersion over a 198 nm wide wavelength range. Chromatic dispersion of dual-slot silicon (Si) waveguide is mainly determined by waveguide dispersion due to the manipulating mode effective area rather than by the material dispersion. Moreover, the nonlinear coefficient and effective mode area of the waveguide are also explored in detail. A nonlinear coefficient of 1460/m/W at 1550 nm is achieved, which is 10 times larger than that of the Si rib waveguide. By changing different waveguide variables, both the dispersion and nonlinear coefficient can be tailored, thus enabling the potential for a highly nonlinear waveguide with uniform dispersion over a wide wavelength range, which could benefit the performance of broadband optical signal systems.

  19. SPARCO : a semi-parametric approach for image reconstruction of chromatic objects

    CERN Document Server

    Kluska, J; Berger, J -P; Baron, F; Lazareff, B; Bouquin, J -B Le; Monnier, J D; Soulez, F; Thiébaut, E

    2014-01-01

    The emergence of optical interferometers with three and more telescopes allows image reconstruction of astronomical objects at the milliarcsecond scale. However, some objects contain components with very different spectral energy distributions (SED; i.e. different temperatures), which produces strong chromatic effects on the interferograms that have to be managed with care by image reconstruction algorithms. For example, the gray approximation for the image reconstruction process results in a degraded image if the total (u, v)-coverage given by the spectral supersynthesis is used. The relative flux contribution of the central object and an extended structure changes with wavelength for different temperatures. For young stellar objects, the known characteristics of the central object (i.e., stellar SED), or even the fit of the spectral index and the relative flux ratio, can be used to model the central star while reconstructing the image of the extended structure separately. Methods. We present a new method, c...

  20. INFLUENCE OF CHROMATIC DISPERSION, DISPERSION SLOPE, DISPERSION CURVATURE ON MICROWAVE GENERATION USING TWO CASCADE MODULATORS

    Directory of Open Access Journals (Sweden)

    Mandeep Singh

    2013-03-01

    Full Text Available This work presents a theoretical study of harmonic generation of microwave signals after detection of a modulated optical carrier in cascaded two electro-optic modulators. Dispersion is one of the major limiting factors for microwave generation in microwave photonics. In this paper, we analyze influence of chromatic dispersion, dispersion slope, dispersion curvature on microwave generation using two cascaded MZMs and it has been found that output intensity of photodetector reduces when dispersion term up to fifth order are added. We have used the two cascaded Mach-Zehnder Modulators for our proposed model and tried to show the dispersion effect with the help of modulation depth factor of MZM, which have been not discussed earlier.

  1. Tellurite Composite Microstructured Optical Fibers with Tailored Chromatic Dispersion for Nonlinear Applications

    Science.gov (United States)

    Duan, Zhongchao; Liao, Meisong; Yan, Xin; Kito, Chihiro; Suzuki, Takenobu; Ohishi, Yasutake

    2011-07-01

    We report the fabrication of tellurite composite microstructured optical fibers (CMOFs) which consist of a TeO2-Li2O-WO3-MoO3-Nb2O5 (TLWMN) tellurite glass core and TeO2-ZnO-Na2O-La2O3 (TZNL) tellurite glass cladding. Flattened chromatic dispersion and tunable zero dispersion wavelength (ZDW) were realized in the small core diameter (˜1.5 µm) fiber with six surrounding air holes. The optical loss was measured to be about 4.0 dB/m in the spectral range of 1510-1640 nm. Supercontinuum (SC) generation was demonstrated by a femtosecond laser pumping at 1.55 µm. The threshold pump power for this novel tellurite CMOF was the lowest among tellurite microstructured optical fibers (MOFs).

  2. Humidity sensing behaviour of polyaniline/magnesium chromate (MgCrO4) composite

    Indian Academy of Sciences (India)

    T Machappa; M V N Ambika Prasad

    2012-02-01

    ‘in situ’ polymerization of polyaniline (PANI) was carried out in the presence of magnesium chromate (MgCrO4) to synthesize PANI/ceramic (MgCrO4) composite. These prepared composites were characterized by XRD, FTIR and SEM, which confirm the presence of MgCrO4 in polyaniline matrix. The temperature dependent conductivity measurement shows the thermally activated exponential behaviour of PANI /MgCrO4 composites. The decrease in electrical resistance was observed when the polymer composites were exposed to the broad range of relative humidity (ranging between 20 and 95% RH). This decrease is due to increase in surface electrical conductivity resulting from moisture absorption and due to capillary condensation of water causing change in conductivity within the sensing materials. PANI / MgCrO4 composites are found to be sensitive to low humidity ranging from 20 to 50% RH.

  3. Studies of the chromatic properties and dynamic aperture of the BNL colliding beam accelerator

    International Nuclear Information System (INIS)

    The PATRICIA particle tracking program has been used to study chromatic effects in the Brookhaven CBA (Colliding Beam Accelerator). The short term behavior of particles in the CBA has been followed for particle histories of 300 turns. Contributions from magnet multipoles characteristic of superconducting magnets and closed orbit errors have been included in determining the dynamic aperture of the CBA for on and off momentum particles. The width of the third integer stopband produced by the temperature dependence of magnetization induced sextupoles in the CBA cable dipoles is evaluated for helium distribution systems having periodicity of one and six. The stopband width at a tune of 68/3 is naturally zero for the system having a periodicity of six and is ∫10-4 for the system having a periodicity of one. Results from theory are compared with results obtained with PATRICIA; the results agree within a factor of slightly more than two

  4. An Upper Bound for the Adjacent Vertex Distinguishing Acyclic Edge Chromatic Number of a Graph

    Institute of Scientific and Technical Information of China (English)

    Xin-sheng Liu; Ming-qiang An; Yang Gao

    2009-01-01

    A proper k-edge coloring of a graph G is called adjacent vertex distinguishing acyclic edge coloring if there is no 2-colored cycle in G and the color set of edges incident to u is not equal to the color set of edges incident to v,where uv ∈ E(G).The adjacent vertex distinguishing acyclic edge chromatic number of G,denoted by χαα(G),is the minimal number of colors in an adjacent vertex distinguishing acyclic edge coloring of G.In this paper we prove that if G(V,E)is a graph with no isolated edges,then χαα(G)≤32△.

  5. Simultaneous chromatic dispersion, polarization-mode-dispersion and OSNR monitoring at 40Gbit/s.

    Science.gov (United States)

    Baker-Meflah, Lamia; Thomsen, Benn; Mitchell, John; Bayvel, Polina

    2008-09-29

    A novel method for independent and simultaneous monitoring of chromatic dispersion (CD), first-order PMD and OSNR in 40Gbit/s systems is proposed and demonstrated. This is performed using in-band tone monitoring of 5GHz, optically down-converted to a low intermediate-frequency (IF) of 10kHz. The measurement provides a large monitoring range with good accuracies for CD (4742+/-100ps/nm), differential group delay (DGD) (200+/-4ps) and OSNR (23+/-1dB), independently of the bit-rate. In addition, the use of electro-absorption modulators (EAM) for the simultaneous down-conversion of all channels and the use of low-speed detectors makes it cost effective for multi-channel operation.

  6. Feed-Forward Corrections for Tune and Chromaticity Injection Decay During 2015 LHC Operation

    CERN Document Server

    Solfaroli Camillocci, Matteo; Lamont, Mike; Schaumann, Michaela; Todesco, Ezio; Wenninger, Jorg

    2016-01-01

    After two years of shutdown, the Large Hadron Collider (LHC) has been operated in 2015 at 6.5 TeV, close to its designed energy. When the current is stable at low field, the harmonic components of the main circuits are subject to a dynamic variation induced by current redistribution on the superconducting cables. The Field Description of the LHC (FiDel) foresaw an increase of the decay at injection of tune (quadrupolar components) and chromaticity (sextupolar components) of about 50% with respect to LHC Run1 due to the higher operational current. This paper discusses the beam-based measurements of the decay during the injection plateau and the implementation and accuracy of the feed-forward corrections as present in 2015. Moreover, the observed tune shift proportional to the circulating beam intensity and it's foreseen feed-forward correction are covered.

  7. Use of sodium chromate Cr51 in diagnosing childhood idiopathic pulmonary hemosiderosis

    International Nuclear Information System (INIS)

    The diagnosis of idiopathic pulmonary hemosiderosis (IPH) may be elusive. A 6-year-old boy had microcytic hypochromic anemia and a hemolytic component. Hemosiderin-laden macrophages were not found in the gastric aspirate. He had no pulmonary signs or symptoms. Extensive hematologic and roentgenologic investigations failed to reveal the cause of the anemia. Quantitative serial scintigraphic scanning showed significant (35%) pulmonary sequestration of autologous erythrocytes labeled with sodium chromate Cr51. The half-life of the RBCs was moderately decreased (half-life, 15 days; normal, 25 to 35 days). An open-lung biopsy spece Cr51. The half-life of the RBCs was moderately decreased (half-life, 15 days; normal, 25 to 35 days). An open-lung biopsy specimen confirmed the diagnosis of IPH. A diagnosis of IPH should be considered when children have iron deficiency anemia and pulmonary signs or symptoms. Organ sequestration studies may be helpful in equivocal cases

  8. Chromatic effects in beam wander correction for free-space quantum communications

    CERN Document Server

    Carrasco-Casado, Alberto; Fernandez, Veronica

    2016-01-01

    Beam wander caused by atmospheric turbulence can significantly degrade the performance of horizontal free-space quantum communication links. Classical beam wander correction techniques cannot be applied due to the stronger requirements of transmitting single photons. One strategy to overcome this limitation consists in using a separate wavelength from that of the quantum signal to analyze the beam wander and use this information for its correction. For this strategy to work adequately, both wavelengths should be affected equally by atmospheric turbulence, i.e. no chromatic effects should be originated from beam wander. In this letter, a series of experiments are performed to prove that this is the case for {\\lambda} ~ 850 nm as the quantum signal and {\\lambda} ~ 1550 nm as the tracking signal of a quantum communication system.

  9. [Chemical composition and chromaticity characteristic of Jilan glaze of Ming and Qing official kilns].

    Science.gov (United States)

    Wu, Jun-ming; Zhang, Mao-lin; Li, Qi-jiang; Wu, Juan; Quan, Kui-shan; Cao, Jian-wen

    2012-08-01

    Color glazes of Ming and Qing official kilns are excellent representatives of the famous ancient Chinese porcelains. The study of official ware with Jilan glaze has been an important topic. But it made slow progress due to the rarity of samples with strict production management and using system. The recipes, chemical composition and chromaticity characteristic of the Jilan samples excavated from official kilns in the Ming and Qing dynasties were first discussed by systematical testing with the energy dispersive X-ray fluorescence (EDXRF) and color difference meter. The results showed that the porcelain stone content in Jilan bodies of official kiln in the Ming dynasty is higher than the samples of the Qing dynasty. The manganese content in Jilan glazes of the Ming dynasty is higher than that in the Qing dynasty, while the glaze ash addition and the lightness value in the glaze are opposite. PMID:23156793

  10. Chromaticity of the lattice and beam stability in energy-recovery linacs

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, V.N.

    2011-12-23

    Energy recovery linacs (ERLs) are an emerging generation of accelerators promising to revolutionize the fields of high-energy physics and photon sciences. These accelerators combine the advantages of linear accelerators with that of storage rings, and hold the promise of delivering electron beams of unprecedented power and quality. Use of superconducting radio-frequency (SRF) cavities converts ERLs into nearly perfect 'perpetuum mobile' accelerators, wherein the beam is accelerated to a desirable energy, used, and then gives the energy back to the RF field. One potential weakness of these devices is transverse beam break-up instability that could severely limit the available beam current. In this paper, I present a method of suppressing these dangerous effects using a natural phenomenon in the accelerators, viz., the chromaticity of the transverse motion.

  11. Performance Of Five Chromatic Adaptation Transforms Using Large Number Of Color Patches

    Directory of Open Access Journals (Sweden)

    Aleš Hladnik

    2009-01-01

    Full Text Available Input devices in general use light sources with different color temperatures. As a consequence, in color acquisition, display and rendering processes a number of chromatic adaptations transforms (cats are being used. In our study, color transformations between three illuminant source pairs (d50-a, d50-d65 and d65-a were investigated using five cats (Bradford, von Kries, xyz Scaling, cmccat97 and cmccat00. Research was made on 8190 color patches that were printed with inkjet printer. Results showed that color differences obtained with the Bradford method were the lowest regardless of the implemented illuminant source pair. The same ranking of cats was observed in all combination of illuminant source pairs, however the smallest color differences were generated with d50-d65 cats and the biggest with d65-a models.

  12. Performance Of Five Chromatic Adaptation Transforms Using Large Number Of Color Patches

    Directory of Open Access Journals (Sweden)

    Dajana Dordevic

    2009-11-01

    Full Text Available Input devices in general use light sources with different color temperatures. As a consequence, in color acquisition, display and rendering processes a number of chromatic adaptations transforms (CATS are being used. In our study, color transformations between three illuminant source pairs (D50-A, D50-D65 and D65-A were investigated using five cats (Bradford, von Kries, XYZ Scaling, CMCCAT97 and CMCCAT00. Research was made on 8190 color patches that were printed with inkjet printer. Results showed that color differences obtained with the Bradford method were the lowest regardless of the implemented illuminant source pair. The same ranking of CATSwas observed in all combinations of illuminant source pairs, however the smallest color differences were generated with D50-D65 CATS and the biggest with D65-A models.

  13. Separation/Preconcentration and Speciation Analysis of Trace Amounts of Arsenate and Arsenite in Water Samples Using Modified Magnetite Nanoparticles and Molybdenum Blue Method

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Karimi

    2014-01-01

    Full Text Available A new, simple, and fast method for the separation/preconcentration and speciation analysis of arsenate and arsenite ions using cetyltrimethyl ammonium bromide immobilized on alumina-coated magnetite nanoparticles (CTAB@ACMNPs followed by molybdenum blue method is proposed. The method is based on the adsorption of arsenate on CTAB@ACMNPs. Total arsenic in different samples was determined as As(V after oxidation of As(III to As(V using potassium permanganate. The arsenic concentration has been determined by UV-Visible spectrometric technique based on molybdenum blue method and amount of As(III was calculated by subtracting the concentration of As(V from total arsenic concentration. MNPs and ACMNPs were characterized by VSM, XRD, SEM, and FT-IR spectroscopy. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range, and relative standard deviation (RSD of arsenate were 175 (for 350 mL of sample solution, 0.028 μg mL−1, 0.090–4.0 μg mL−1, and 2.8% (for 2.0 μg mL−1, n=7, respectively. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of CTAB@ACMNPs with an adscititious magnet. The proposed method was successfully applied to the determination and speciation of arsenic in different water samples and suitable recoveries were obtained.

  14. [Chemical composition and chromaticity characteristic of purple-gold glaze of Jingdezhen imperial kiln].

    Science.gov (United States)

    Wu, Jun-Ming; Li, Qi-Jiang; Zhang, Mao-Lin; Ding, Yin-Zhong; Cao, Jian-Wen; Liu, Xiao-Jing

    2014-03-01

    Color glaze is one of the four famous traditional ceramics of Jingdezhen, especially for the products from Ming and Qing Dynasties' official kilns which have rich connotation of technology and culture. The chemical composition and chromaticity characteristic of glaze and body of purple-gold glaze samples from Jingdezhen Ming and Qing Dynasties' official kilns were analyzed by energy dispersive X ray fluorescence (EDXRF) and colorimeter. Preliminary study on the composition, formula and chromaticity characteristic of glaze of purple-gold glaze samples of different period was carried out and the intrinsic causes of ifferences were discussed. The result shows that the concentration of magnesium and calcium in purple-gold glaze is different from the other glazes in Jingdezhen in the same time, probably due to the addition of auburn or brown limestone which is rich in magnesium. The purple-gold glaze sample of Ming Dynasty is darker chiefly because the concentration of magnesium and calcium is higher than the sample of Ming Dynasty which led to iron crystal separated, reducing the brightness and glossiness of glaze. In addition, the body of purple-gold glaze samples from Jingdezhen Ming and Qing Dynasties' official kilns has the characteristics of high silicon and low aluminum and the molar ratio of silicon to aluminum of samples from Ming Dynasty to Qing Dynasty declined, showing that the concentration of kaolin of sample's body of Ming dynasty was increased. The result of this experiment fill deficiency in the ceramic science and technology research in our country about purple-gold glaze from Ming and Qing Dynasties' official kilns and provides scientific material for comprehensive understanding of porcelain marking technology and intrinsic value of Jingdezhen official kiln. PMID:25208422

  15. Creation of a subsurface permeable treatment zone for aqueous chromate contamination using in situ redox manipulation

    International Nuclear Information System (INIS)

    An in situ redox manipulation (ISRM) method for creating a permeable treatment zone in the subsurface has been developed at the laboratory bench and intermediate scales and deployed at the field scale for reduction/immobilization of chromate contamination. At other sites, the same redox technology is currently being tested for dechlorination of TCE. The reduced zone is created by injected reagents that reduce iron naturally present in the aquifer sediments from Fe(III) to surface-bound and structural Fe(II) species. Standard ground water wells are used, allowing treatment of contaminants too deep below the ground surface for conventional trench-and-fill technologies. A proof-of-principle field experiment was conducted in September 1995 at a chromate (hexavalent chromium) contaminated ground water site on the Hanford Site in Washington. The test created a 15 m diameter cylindrical treatment zone. The three phases of the test consisted of (1) injection of 77,000 L of buffered sodium dithionite solution in 17.1 hours, (2) reaction for 18.5 hours, and (3) withdrawal of 375,000 L in 83 hours. The withdrawal phase recovered 87% to 90% of the reaction products. Analysis of post-experimental sediment cores indicated that 60% to 100% of the available reactive iron in the treated zone was reduced. The longevity of the reduced zone is estimated between seven and 12 years based on the post-experiment core samples. Three and half years after the field test, the treatment zone remains anoxic, and hexavalent chromium levels have been reduced from 0.060 mg/L to below detection limits (0.008 mg/L). Additionally, no significant permeability changes have been detected during any phase of the experiment

  16. Chromatically encoded high-speed photography of cavitation bubble dynamics inside inhomogeneous ophthalmic tissue

    Science.gov (United States)

    Tinne, N.; Matthias, B.; Kranert, F.; Wetzel, C.; Krüger, A.; Ripken, T.

    2016-03-01

    The interaction effect of photodisruption, which is used for dissection of biological tissue with fs-laser pulses, has been intensively studied inside water as prevalent sample medium. In this case, the single effect is highly reproducible and, hence, the method of time-resolved photography is sufficiently applicable. In contrast, the reproducibility significantly decreases analyzing more solid and anisotropic media like biological tissue. Therefore, a high-speed photographic approach is necessary in this case. The presented study introduces a novel technique for high-speed photography based on the principle of chromatic encoding. For illumination of the region of interest within the sample medium, the light paths of up to 12 LEDs with various emission wavelengths are overlaid via optical filters. Here, MOSFET-electronics provide a LED flash with a duration <100 ns; the diodes are externally triggered with a distinct delay for every LED. Furthermore, the different illumination wavelengths are chromatically separated again for detection via camera chip. Thus, the experimental setup enables the generation of a time-sequence of <= 12 images of a single cavitation bubble dynamics. In comparison to conventional time-resolved photography, images in sample media like water and HEMA show the significant advantages of this novel illumination technique. In conclusion, the results of this study are of great importance for the fundamental evaluation of the laser-tissue interaction inside anisotropic biological tissue and for the optimization of the surgical process with high-repetition rate fs-lasers. Additionally, this application is also suitable for the investigation of other microscopic, ultra-fast events in transparent inhomogeneous materials.

  17. Production of a microcapsule agent of chromate-reducing Lysinibacillus fusiformis ZC1 and its application in remediation of chromate-spiked soil.

    Science.gov (United States)

    Huang, Jun; Li, Jingxin; Wang, Gejiao

    2016-01-01

    Lysinibacillus fusiformis ZC1 is an efficient Cr(VI)-reducing bacterium that can transform the toxic and soluble chromate [Cr(VI)] form to the less toxic and precipitated chromite form [Cr(III)]. As such, this strain might be applicable for bioremediation of Cr(VI) in soil by reducing its bioavailability. The study objective was to prepare a microcapsule agent of strain ZC1 for bioremediation of Cr(VI)-contaminated soil. Using a single-factor orthogonal array design, the optimal fermentation medium was obtained and consisted of 6 g/L corn flour, 12 g/L soybean flour, 8 g/L NH4Cl and 6 g/L CaCl2. After enlarged fermentation, the cell and spore densities were 5.9 × 10(9) and 1.7 × 10(8) cfu/mL, respectively. The fermentation products were collected and embedded with 1 % gum arabic and 1 % sorbitol as the microcapsule carriers and were subsequently spray-dried. Strain ZC1 exhibited viable cell counts of (3.6 ± 0.44) × 10(10) cfu/g dw after 50-day storage at room temperature. In simulated soil bioremediation experiments, 67 % of Cr(VI) was reduced in 5 days with the inoculation of this microcapsule agent, and the Cr(VI) concentration was below the soil Cr(VI) standard level. The results demonstrated that the microcapsule agent of strain ZC1 is efficient for bioremediation of Cr(VI)-contaminated soil.

  18. Multilevel cycle of anthropogenic copper.

    Science.gov (United States)

    Graedel, T E; van Beers, D; Bertram, M; Fuse, K; Gordon, R B; Gritsinin, A; Kapur, A; Klee, R J; Lifset, R J; Memon, L; Rechberger, H; Spatari, S; Vexler, D

    2004-02-15

    A comprehensive contemporary cycle for stocks and flows of copper is characterized and presented, incorporating information on extraction, processing, fabrication and manufacturing, use, discard, recycling, final disposal, and dissipation. The analysis is performed on an annual basis, ca. 1994, at three discrete governmental unit levels--56 countries or country groups that together comprise essentially all global anthropogenic copper stocks and flows, nine world regions, and the planet as a whole. Cycles for all of these are presented and discussed, and a "best estimate" global copper cycle is constructed to resolve aggregation discrepancies. Among the most interesting results are (1) transformation rates and recycling rates in apparently similar national economies differ by factors of two or more (country level); (2) the discard flows that have the greatest potential for copper recycling are those with low magnitude flows but high copper concentrations--electronics, electrical equipment, and vehicles (regional level); (3) worldwide, about 53% of the copper that was discarded in various forms was recovered and reused or recycled (global level); (4) the highest rate of transfer of discarded copper to repositories is into landfills, but the annual amount of copper deposited in mine tailings is nearly as high (global level); and (5) nearly 30% of copper mining occurred merely to replace copper that was discarded. The results provide a framework for similar studies of other anthropogenic resource cycles as well as a basis for supplementary studies in resource stocks, industrial resource utilization, waste management, industrial economics, and environmental impacts. PMID:14998044

  19. Molecular characterization of Alr1105 a novel arsenate reductase of the diazotrophic cyanobacterium Anabaena sp. PCC7120 and decoding its role in abiotic stress management in Escherichia coli.

    Science.gov (United States)

    Pandey, Sarita; Shrivastava, Alok K; Rai, Rashmi; Rai, Lal Chand

    2013-11-01

    This paper constitutes the first report on the Alr1105 of Anabaena sp. PCC7120 which functions as arsenate reductase and phosphatase and offers tolerance against oxidative and other abiotic stresses in the alr1105 transformed Escherichia coli. The bonafide of 40.8 kDa recombinant GST+Alr1105 fusion protein was confirmed by immunoblotting. The purified Alr1105 protein (mw 14.8 kDa) possessed strong arsenate reductase (Km 16.0 ± 1.2 mM and Vmax 5.6 ± 0.31 μmol min⁻¹ mg protein⁻¹) and phosphatase activity (Km 27.38 ± 3.1 mM and Vmax 0.077 ± 0.005 μmol min⁻¹ mg protein⁻¹) at an optimum temperature 37 °C and 6.5 pH. Native Alr1105 was found as a monomeric protein in contrast to its homologous Synechocystis ArsC protein. Expression of Alr1105 enhanced the arsenic tolerance in the arsenate reductase mutant E. coli WC3110 (∆arsC) and rendered better growth than the wild type W3110 up to 40 mM As (V). Notwithstanding above, the recombinant E. coli strain when exposed to CdCl₂, ZnSO₄, NiCl₂, CoCl₂, CuCl₂, heat, UV-B and carbofuron showed increase in growth over the wild type and mutant E. coli transformed with the empty vector. Furthermore, an enhanced growth of the recombinant E. coli in the presence of oxidative stress producing chemicals (MV, PMS and H₂O₂), suggested its protective role against these stresses. Appreciable expression of alr1105 gene as measured by qRT-PCR at different time points under selected stresses reconfirmed its role in stress tolerance. Thus the Alr1105 of Anabaena sp. PCC7120 functions as an arsenate reductase and possess novel properties different from the arsenate reductases known so far.

  20. Tongling:Copper Industry Giant Takes Shape

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>Centering on the strategic goal of building "World Copper Capital", Tongling constantly extends its product lines and improves the copper industry chain. Now, the copper industry with a production value of RMB 100 billion has taken shape.As the largest copper wire rod manufacturer in Asia, Tongling Quanwei Copper Technologies Co., Ltd., upon its moving into the local market,

  1. Arsenate Impact on the Metabolite Profile, Production, and Arsenic Loading of Xylem Sap in Cucumbers (Cucumis sativus L.).

    Science.gov (United States)

    Uroic, M Kalle; Salaün, Pascal; Raab, Andrea; Feldmann, Jörg

    2012-01-01

    Arsenic uptake and translocation studies on xylem sap focus generally on the concentration and speciation of arsenic in the xylem. Arsenic impact on the xylem sap metabolite profile and its production during short term exposure has not been reported in detail. To investigate this, cucumbers were grown hydroponically and arsenate (As(V)) and DMA were used for plant treatment for 24 h. Total arsenic and arsenic speciation in xylem sap was analyzed including a metabolite profiling under As(V) stress. Produced xylem sap was quantified and absolute arsenic transported was determined. As(V) exposure had a significant impact on the metabolite profile of xylem sap. Four m/z values corresponding to four compounds were up-regulated, one compound down-regulated by As(V) exposure. The compound down-regulated was identified to be isoleucine. Furthermore, As(V) exposure had a significant influence on sap production, leading to a reduction of up to 96% sap production when plants were exposed to 1000 μg kg(-1) As(V). No difference to control plants was observed when plants were exposed to 1000 μg kg(-1) DMA. Absolute arsenic amount in xylem sap was the lowest at high As(V) exposure. These results show that As(V) has a significant impact on the production and metabolite profile of xylem sap. The physiological importance of isoleucine needs further attention.

  2. Transcriptomics profiling of Indian mustard (Brassica juncea) under arsenate stress identifies key candidate genes and regulatory pathways.

    Science.gov (United States)

    Srivastava, Sudhakar; Srivastava, Ashish K; Sablok, Gaurav; Deshpande, Tejaswini U; Suprasanna, Penna

    2015-01-01

    Arsenic (As) is a non-essential element, a groundwater pollutant, whose uptake by plants produces toxic effects. The use of As-contaminated groundwater for irrigation can affect the crop productivity. Realizing the importance of the Brassica juncea as a crop plant in terms of oil-yield, there is a need to unravel mechanistic details of response to As stress and identify key functional genes and pathways. In this research, we studied time-dependent (4-96 h) transcriptome changes in roots and shoots of B. juncea under arsenate [As(V)] stress using Agilent platform. Among the whole transcriptome profiled genes, a total of 1,285 genes showed significant change in expression pattern upon As(V) exposure. The differentially expressed genes were categorized to various signaling pathways including hormones (jasmonate, abscisic acid, auxin, and ethylene) and kinases. Significant effects were also noticed on genes related to sulfur, nitrogen, CHO, and lipid metabolisms along with photosynthesis. Biochemical assays were conducted using specific inhibitors of glutathione and jasmonate biosynthesis, and kinases. The inhibitor studies revealed interconnection among sulfur metabolism, jasmonate, and kinase signaling pathways. In addition, various transposons also constituted a part of the altered transcriptome. Lastly, we profiled a set of key functional up- and down-regulated genes using real-time RT-PCR, which could act as an early indicators of the As stress.

  3. Raman spectroscopic identification of arsenate minerals in situ at outcrops with handheld (532 nm, 785 nm) instruments.

    Science.gov (United States)

    Culka, Adam; Kindlová, Helena; Drahota, Petr; Jehlička, Jan

    2016-02-01

    Minerals are traditionally identified under field conditions by experienced mineralogists observing the basic physical properties of the samples. Under laboratory conditions, a plethora of techniques are commonly used for identification of the geological phases based on their structural and spectroscopic parameters. In this area, Raman spectrometry has become a useful tool to complement the more widely applied XRD. Today, however, there is an acute need for a technique for unambiguous in situ identification of minerals, within the geological as well as planetary/exobiology realms. With the potential for miniaturization, Raman spectroscopy can be viewed as a practical technique to achieve these goals. Here, for the first time, the successful application of handheld Raman spectrometers is demonstrated to detect and discriminate arsenic phases in the form of earthy aggregates. The Raman spectroscopic analyses of arsenate minerals were performed in situ using two handheld instruments, using 532 and 785 nm excitation. Bukovskýite, kaňkite, parascorodite, and scorodite were identified from Kaňk near Kutná Hora, CZE; kaňkite, scorodite, and zýkaite were identified at the Lehnschafter gallery in an old silver mine at Mikulov near Teplice, Bohemian Massif, CZE. PMID:26523686

  4. Slurry bioreactor modeling using a dissimilatory arsenate-reducing bacterium for remediation of arsenic-contaminated soil.

    Science.gov (United States)

    Soda, Satoshi; Kanzaki, Masaya; Yamamuara, Shigeki; Kashiwa, Masami; Fujita, Masanori; Ike, Michihiko

    2009-02-01

    A slurry bioreactor using a dissimilatory arsenate (As(V))-reducing bacterium is proposed for remediation of arsenic-contaminated soils. Bacterial As(V) reduction can cause arsenic extraction from the solid to the liquid phase because arsenite, As(III), is much less adsorptive than As(V). A mathematical model was developed incorporating the reversible sorption process of arsenic as well as bacterial growth and decay via As(V) reduction. A linear isotherm equation expressed the sorption process. The model included Haldane kinetics with high As(V) concentrations and cell inactivation by toxicity due to As(III). Extraction experiments used synthetic contaminated soils (forest soil, Soil SF, 1100 mg kg(-1); paddy soil, Soil SP, 1100 mg kg(-1)) and actual contaminated soils (Soil AH 2200 mg kg(-1) and Soil AL, 220 mg kg(-1)) at 5% w/v slurry concentration. Simulation results matched the observed changes of arsenic concentrations in the liquid phase. The respective extraction efficiencies of arsenic were 63%, 41%, 20%, and 55% for SF, SP, AH, and AL soils. Sensitivity analyses showed that the rate-limiting step was the desorption rate of As(V) from the solid to the liquid phase, rather than the As(V)-reducing rate. The proposed model provides a useful framework for understanding and predicting the extraction of arsenic from soil.

  5. Effects of arsenate (AS5+) on growth and production of glutathione (GSH) and phytochelatins (PCS) in Chlorella vulgaris.

    Science.gov (United States)

    Jiang, Ying; Purchase, Diane; Jones, Huw; Garelick, Hemda

    2011-09-01

    The effect of arsenate (As5+) on growth and chlorophyll a production in Chlorella vulgaris, its removal by C. vulgaris and the role of glutathione (GSH) and phytochelatins (PCs) were investigated. C. vulgaris was tolerant to As5+ at up to 200 mg/L and was capable of consistently removing around 70% of the As5+ present in growth media over a wide range of exposure concentrations. Spectral analysis revealed that PCs and their arsenic-combined complexes were absent, indicating that the high bioaccumulation and tolerance to arsenic observed was not due to intracellular chelation. In contrast, GSH was found in all samples ranging from 0.8 mg/L in the control to 6.5 mg/L in media containing 200 mg/L As5+ suggesting that GSH plays a more prominent role in the detoxification of As5+ in C. vulgaris than PC. At concentrations below 100 mg/L cell surface binding and other mechanisms may play the primary role in As5+ detoxification, whereas above this concentration As5+ begins to accumulate inside the algal cells and activates a number of intracellular cell defense mechanisms, such as increased production of GSH. The overall findings complement field studies which suggest C. vulgaris as an increasingly promising low cost As phytoremediation method for developing countries.

  6. Natural variations in expression of regulatory and detoxification related genes under limiting phosphate and arsenate stress in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Tapsi eShukla

    2015-10-01

    Full Text Available Abiotic stress including nutrient deficiency and heavy metal toxicity severely affects plant growth, development, and productivity. Genetic variations within and in between species are one of the important factors in establishing interactions and responses of plants with the environment. In the recent past, natural variations in Arabidopsis thaliana have been used to understand plant development and response towards different stresses at genetic level. Phosphorus (Pi deficiency negatively affects plant growth and metabolism and modulates expression of the genes involved in Pi homeostasis. Arsenate, As(V, a chemical analogue of Pi, is taken up by the plants via phosphate transport system. Studies suggest that during Pi deficiency, enhanced As(V uptake leads to increased toxicity in plants. Here, the natural variations in Arabidopsis have been utilized to study the As(V stress response under limiting Pi condition. The primary root length was compared to identify differential response of three Arabidopsis accessions (Col-0, Sij-1 and Slavi-1 under limiting Pi and As(V stress. To study the molecular mechanisms responsible for the differential response, comprehensive expression profiling of the genes involved in uptake, detoxification and regulatory mechanisms was carried out. Analysis suggests genetic variation-dependent regulatory mechanisms may affect differential response of Arabidopsis natural variants towards As(V stress under limiting Pi condition. Therefore, it is hypothesized that detailed analysis of the natural variations under multiple stress conditions might help in the better understanding of the biological processes involved in stress tolerance and adaptation.

  7. Determination of arsenate in water by anion selective membrane electrode using polyurethane–silica gel fibrous anion exchanger composite

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Asif Ali, E-mail: asifkhan42003@yahoo.com; Shaheen, Shakeeba, E-mail: shakeebashaheen@ymail.com

    2014-01-15

    Highlights: • PU–Si gel is new anion exchanger material synthesized and characterized. • This material used as anion exchange membrane is applied for electroanalytical studies. • The method for detection and determination of AsO{sub 4}{sup 3−} in traces amounts discussed. • The results are also verified from arsenic analyzer. -- Abstract: Polyurethane (PU)–silica (Si gel) based fibrous anion exchanger composites were prepared by solid–gel polymerization of polyurethane in the presence of different amounts of silica gel. The formation of PU–Si gel fibrous anion exchanger composite was characterized by Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTA), scanning electron microscopy (SEM) and elemental analysis. The membrane having a composition of 5:3 (PU:Si gel) shows best results for water content, porosity, thickness and swelling. Our studies show that the present ion selective membrane electrode is selective for arsenic, having detection limit (1 × 10{sup −8} M to 1 × 10{sup −1} M), response time (45 s) and working pH range (5–8). The selectivity coefficient values for interfering ions indicate good selectivity for arsenate (AsO{sub 4}{sup 3−}) over interfering anions. The accuracy of the detection limit results was compared by PCA-Arsenomat.

  8. Determination of arsenate in water by anion selective membrane electrode using polyurethane-silica gel fibrous anion exchanger composite.

    Science.gov (United States)

    Khan, Asif Ali; Shaheen, Shakeeba

    2014-01-15

    Polyurethane (PU)-silica (Si gel) based fibrous anion exchanger composites were prepared by solid-gel polymerization of polyurethane in the presence of different amounts of silica gel. The formation of PU-Si gel fibrous anion exchanger composite was characterized by Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTA), scanning electron microscopy (SEM) and elemental analysis. The membrane having a composition of 5:3 (PU:Si gel) shows best results for water content, porosity, thickness and swelling. Our studies show that the present ion selective membrane electrode is selective for arsenic, having detection limit (1×10(-8)M to 1×10(-1)M), response time (45s) and working pH range (5-8). The selectivity coefficient values for interfering ions indicate good selectivity for arsenate (AsO4(3-)) over interfering anions. The accuracy of the detection limit results was compared by PCA-Arsenomat.

  9. Synthesis, crystal structure and charge distribution of Na7As11O31: An oxygen-deficient layered sodium arsenate

    International Nuclear Information System (INIS)

    A new sodium arsenate with layer structure has been synthesized and its crystal structure solved and refined by single-crystal X-ray diffraction. The crystal is trigonal, space group P3-bar m1, a=11.199(3)A, c=5.411(2)A, V=587.80(3)A3, Z=1; the refinement converged to R=0.0282 and wR=0.0751 for 590 reflections with (I)>2sigma(I). The structural model gives the formula Na7As11O32, which would be non-neutral; besides, the structural model is not validated by the charge distribution (CD) analysis, which gives an unsatisfactory agreement on the computed charges of the cations. The CD analysis suggest incomplete (5/6) occupation of the O5 site, which leads to the deficiency of an oxygen atom per unit cell and to formula Na7As11O31: this new structural model corresponds to a neutral compound, is validated by the CD analysis, and results in better displacement parameters for O5 than its non neutral counterpart. The (001) anionic layers are built up from corner and edge sharing of As1 and As2 distorted octahedra and As3 distorted tetrahedra, the sodium cations playing the role of interlayer cations. The effects of the oxygen deficiency on the crystal structure are discussed

  10. Direct Production of Copper

    Science.gov (United States)

    Victorovich, G. S.; Bell, M. C.; Diaz, C. M.; Bell, J. A. E.

    1987-09-01

    The use of commercially pure oxygen in flash smelting a typical chalcopyrite concentrate or a low grade comminuted matte directly to copper produces a large excess of heat. The heat balance is controlled by adjusting the calorific value of the solid feed. A portion of the sulfide material is roasted to produce a calcine which is blended with unroasted material, and the blend is then autogeneously smelted with oxygen and flux directly to copper. Either iron silicate or iron calcareous slags are produced, both being subject to a slag cleaning treatment. Practically all of the sulfur is contained in a continuous stream of SO2 gas, most of which is strong enough for liquefaction. A particularly attractive feature of these technologies is that no radically new metallurgical equipment needs to be developed. The oxygen smelting can be carried out not only in the Inco type flash furnace but in other suitable smelters such as cyclone furnaces. Another major advantage stems from abolishion of the ever-troublesome converter aisle, which is replaced with continuous roasting of a fraction of the copper sulfide feed.

  11. Copper minerals under the microscope

    OpenAIRE

    Hjeltström, Anna

    2015-01-01

    From many perspectives copper is a very important metal for the modern society. It can be found in everything from jewellery to electronics. For this reason it is very important for geologists to be able to develop efficient methods for identification, characterisation, extraction and processing of copper. One method for the identification of copper bearing minerals is ore microscopy which has been used in this paper along with a general introduction. Samples from the study collection of the ...

  12. Copper and copper-nickel-alloys - An overview

    Energy Technology Data Exchange (ETDEWEB)

    Klassert, Anton; Tikana, Ladji [Deutsches Kupferinstitut e.V. Am Bonneshof 5, 40474 Duesseldorf (Germany)

    2004-07-01

    With the increasing level of industrialization the demand for and the number of copper alloys rose in an uninterrupted way. Today, the copper alloys take an important position amongst metallic materials due to the large variety of their technological properties and applications. Nowadays there exist over 3.000 standardized alloys. Copper takes the third place of all metals with a worldwide consumption of over 15 millions tons per year, following only to steel and aluminum. In a modern industrial society we meet copper in all ranges of the life (electro-technology, building and construction industry, mechanical engineering, automotive, chemistry, offshore, marine engineering, medical applications and others.). Copper is the first metal customized by humanity. Its name is attributed to the island Cyprus, which supplied in the antiquity copper to Greece, Rome and the other Mediterranean countries. The Romans called it 'ore from Cyprus' (aes cyprium), later cuprum. Copper deposited occasionally also dapper and could be processed in the recent stone age simply by hammering. Already in early historical time copper alloys with 20 to 50 percent tin was used for the production of mirrors because of their high reflecting power. Although the elementary nickel is an element discovered only recently from a historical perspective, its application in alloys - without any knowledge of the alloy composition - occurred at least throughout the last 2.000 years. The oldest copper-nickel coin originates from the time around 235 B.C.. Only around 1800 AD nickel was isolated as a metallic element. In particular in the sea and offshore technology copper nickel alloys found a broad field of applications in piping systems and for valves and armatures. The excellent combination of characteristics like corrosion resistance, erosion stability and bio-fouling resistance with excellent mechanical strength are at the basis of this success. An experience of many decades supports the use

  13. Mechanochemical reactions on copper-based compounds

    NARCIS (Netherlands)

    H.L. Castricum; H. Bakker; E.K. Poels

    1998-01-01

    Mechanochemical reactions of copper and copper oxides with oxygen and carbon dioxide are discussed, as well as decomposition and reduction of copper compounds by mechanical milling under high-vacuum conditions.

  14. Polarization Studies on Inhibitory Effect of Chromates and Dichromates on Corrosion of Tin Coated Steel in 0.5M Monochloroacetic Acid

    Directory of Open Access Journals (Sweden)

    Sangita Sharma

    2008-01-01

    Full Text Available Chromates and Dichromates have been tested for its inhibitory effects towards tin coated steel in 0.5M monochloroacetic acid. The corrosion behaviour of potassium chromate, sodium chromate, potassium dichromate, sodium dichromate and ammonium dichromate was studied by polarization curves, Tafel parameters like Tafel slopes, extrapolation of cathodic Tafel line and intersection of cathodic and anodic line at open circuit potential in presence of inhibitors have been tabulated along with other electrochemical parameters and corrosion current have been calculated from Tafel lines. The efficiencies are calculated and compared reasonably well with those obtained from loss in weight data. All the inhibitors induce a significant increase of potential positive and direction accounts for cathodic polarization. The Icorr has also been calculated and that accounts well for cathodic reactions in presence of chromates and dichromates as inhibitors.

  15. Study of Copper Substitute in High Copper Price Market Environment

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>The high price of copper drives up industry cost,also it is difficult for terminal products to raise price to transfer the cost pressure brought by increase in copper price,as a result downstream consumption markets instead try to seek

  16. Techniques of copper recovery from Mexican copper oxide ore

    Institute of Scientific and Technical Information of China (English)

    CAO Zhan-fang; ZHONG Hong; LIU Guang-yi; ZHAO Shu-juan

    2009-01-01

    Mexican copper ore is a mixed ore containing mainly copper oxide and some copper sulfide that responds well to flotation. The joint techniques of flotation and leaching were studied. The results indicate that an ore containing 19.01% copper could be obtained at a recovery ratio of 35.02% by using sodium sulfide and butyl xanthate flotation. Over 83.33% of the copper oxide can be recovered from the tailings by leaching in suitable conditions, such as 1 h stirring at a temperature around 25 ℃ with a mixing speed of 500 r/min, an H2SO4 concentration of 1.0 mol/L and a mass ratio of the ore-slurry-liquid to solid (mL/mS) of 3. The overall yield of refined ore after flotation and leaching is over 89.18% of the copper, which is much better than sole flotation or leaching. A copper product containing more than 99.9% copper was obtained by using the process: flotation-agitation leaching-solvent extraction-electro-winning.

  17. Analysis of Early 20th century Chromatic Modal Music with the use of the Generative Theory of Tonal Music - Pitch Space and Prolongational issues in selected modal idioms

    OpenAIRE

    Tsougras, Costas

    2009-01-01

    The Generative Theory of Tonal Music in its original form (Lerdahl & Jackendoff 1983) applied to music belonging to the Western tonal idiom only. However, during the last decade, theoretical and analytical research has been conducted on its application on diatonic or chromatic modal music. More specifically, Lerdahl addresses chromatic pitch spaces in chapters 6 & 7 of his "Tonal Pitch Space" (2001) and conducts analyses of late 19th century and 20th century music, while Temperley (The Cognit...

  18. Optical frequency-domain chromatic dispersion measurement method for higher-order modes in an optical fiber.

    Science.gov (United States)

    Ahn, Tae-Jung; Jung, Yongmin; Oh, Kyunghwan; Kim, Dug Young

    2005-12-12

    We propose a new chromatic dispersion measurement method for the higher-order modes of an optical fiber using optical frequency modulated continuous-wave (FMCW) interferometry. An optical fiber which supports few excited modes was prepared for our experiments. Three different guiding modes of the fiber were identified by using far-field spatial beam profile measurements and confirmed with numerical mode analysis. By using the principle of a conventional FMWC interferometry with a tunable external cavity laser, we have demonstrated that the chromatic dispersion of a few-mode optical fiber can be obtained directly and quantitatively as well as qualitatively. We have also compared our measurement results with those of conventional modulation phase-shift method. PMID:19503215

  19. Influence of Pre- and Post-compensation of Chromatic Dispersion on Equalization Enhanced Phase Noise in Coherent Multilevel Systems

    CERN Document Server

    Jacobsen, Gunnar; Xu, Tianhua; Popov, Sergei; Friberg, Ari T; Zhang, Yimo

    2016-01-01

    In this paper we present a comparative study in order to specify the influence of equalization enhanced phase noise (EEPN) for pre- and post-compensation of chromatic dispersion in high capacity and high constellation systems. This is - to our knowledge - the first detailed study in this area for pre-compensation systems. Our main results show that the local oscillator phase noise determines the EEPN influence in post-compensation implementations whereas the transmitter laser determines the EEPN in pre-compensation implementations. As a result of significance for the implementation of practical longer-range systems it is to be emphasized that the use of chromatic dispersion equalization in the optical domain - e.g. by the use of dispersion compensation fibers - eliminates the EEPN entirely. Thus, this seems a good option for such systems operating at high constellations in the future.

  20. Pupillary responses of chromatic stimulus in the visible spectrum 400 nm of 650 nm, in the stable state

    Science.gov (United States)

    Guzman, D. R.; Lopez, A. Z.; Gomez, E. S.

    2005-08-01

    an instrumental methodology was implemented to analyze the pupillary responses in the dilation and contraction process elicited by chromatic stimulus. Chromatic stimuli were employed in the visible spectrum from 400 nm to 650 nm. Three different stimulation software was developed and used in order to obtain a contrasted pupillary response PG0, PG12 and PG20. This test was applied to 39 subjects (29 male, 9 female and I child, 22-52 years and 6 years), 10 of them were stimulated with PG0, 21 were stimulated with PG12 and 16 with PG20. 6 subjects participate at least in 2 tests. Ishihara plates were exhibited to the Subjects before the stimulation, 37 of the present a normal vision color, I present deuteranopy.

  1. Generation of Flat Supercontinuum in a Single-mode Optical Fiber with a Convex Chromatic Dispersion Profile

    Institute of Scientific and Technical Information of China (English)

    XU Yong-zhao; WANG Hong-chen; ZHOU Shou-li

    2009-01-01

    A single-mode optical fiber with a convex chromatic dispersion profile is proposed for generating a flat supercontinuum(SC). The fiber has normal dispersion and the dispersion parameter D(λ,z) is a convex function of wavelengths. It is shown from the numerical results that the chromatic dispersion, the flatness of the dispersion curve and the pump conditions have significant effect on SC generation. A flat and broad SC without strong residual pump component can be obtained when the pump wavelength is set in the vicinity of the wavelength at which the fiber has small normal group-velocity dispersion(GVD) and small dispersion slope. The fiber with a smaller normal GVD, a flatter dispersion profile and a higher nonlinear coefficient are more suitable for broad SC generation.

  2. Experimental demonstration of adaptive digital monitoring and compensation of chromatic dispersion for coherent DP-QPSK receiver

    DEFF Research Database (Denmark)

    Borkowski, Robert; Zhang, Xu; Zibar, Darko;

    2011-01-01

    We experimentally demonstrate a digital signal processing (DSP)-based optical performance monitoring (OPM) algorithm for inservice monitoring of chromatic dispersion (CD) in coherent transport networks. Dispersion accumulated in 40 Gbit/s QPSK signal after 80 km of fiber transmission is successfu......We experimentally demonstrate a digital signal processing (DSP)-based optical performance monitoring (OPM) algorithm for inservice monitoring of chromatic dispersion (CD) in coherent transport networks. Dispersion accumulated in 40 Gbit/s QPSK signal after 80 km of fiber transmission...... is successfully monitored and automatically compensated without prior knowledge of fiber dispersion coefficient. Four different metrics for assessing CD mitigation are implemented and simultaneously verified proving to have high estimation accuracy. No observable penalty is measured when the monitoring module...

  3. Strong chromatic microlensing in HE0047–1756 and SDSS1155+6346

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, K.; Motta, V. [Instituto de Física y Astronomía, Universidad de Valparaíso, Avda. Gran Bretaña 1111, Playa Ancha, Valparaíso 2360102 (Chile); Mediavilla, E. [Instituto de Astrofísica de Canarias, Avda. Vía Lactea s/n, La Laguna, E-38200 Tenerife (Spain); Falco, E. [Whipple Observatory, Smithsonian Institution, 670 Mt. Hopkins Road, PO Box 6369, Amado, AZ 85645 (United States); Jiménez-Vicente, J. [Departamento de Física Teórica y del Cosmos, Universidad de Granada, Campus de Fuentenueva, E-18071 Granada (Spain); Muñoz, J. A., E-mail: karina.rojas@uv.cl, E-mail: veronica.motta@uv.cl, E-mail: emg@iac.es, E-mail: falco@cfa.harvard.edu, E-mail: jjimenez@ugr.es, E-mail: jmunoz@uv.es [Departamento de Astronomía y Astrofísica, Universidad de Valencia, Burjassot, E-46100 Valencia (Spain)

    2014-12-10

    We use spectra of the double-lensed quasars HE0047–1756 and SDSS1155+6346 to study their unresolved structure through the impact of microlensing. There is no significant evidence of microlensing in the emission line profiles except for the Lyα line of SDSS1155+6346, which shows strong differences in the shapes for images A and B. However, the continuum of the B image spectrum in SDSS1155+6346 is strongly contaminated by the lens galaxy, and these differences should be considered with caution. Using the flux ratios of the emission lines for image pairs as a baseline to remove macro-magnification and extinction, we have detected strong chromatic microlensing in the continuum measured by CASTLES (www.cfa.harvard.edu/castles/) in both lens systems, with amplitudes 0.09(λ16000) ≲ |Δm| ≲ 0.8(λ5439) for HE0047–1756, and 0.2(λ16000) ≲ |Δm| ≲ 0.8(λ5439) for SDSS1155+6346. Using magnification maps to simulate microlensing and modeling the accretion disk as a Gaussian source (I ∝ exp(–R {sup 2}/2r {sub s}{sup 2})) of size r {sub s} ∝ λ {sup p}, we find r {sub s} = 2.5{sub −1.4}{sup +3.0} √(M/0.3M{sub ⊙}) lt-day and p = 2.3 ± 0.8 at the rest frame for λ = 2045 for HE0047–1756 (log prior) and r {sub s} = 5.5{sub −3.3}{sup +8.2} √(M/0.3M{sub ⊙}) lt-day and p = 1.5 ± 0.6 at the rest frame of λ = 1398 for SDSS1155+6346 (log prior). Contrary to other studied lens systems, the chromaticity detected in HE0047–1756 and SDSS1155+6346 is large enough to fulfill the thin disk prediction. The inferred sizes, however, are very large compared to the predictions of this model, especially in the case of SDSS1155+6346.

  4. Design procedure for photonic crystal fibers with ultra-flattened chromatic dispersion

    Institute of Scientific and Technical Information of China (English)

    Huizhen Xu; Jian Wu; Yitang Dai; Cong Xu; Jintong Lin

    2011-01-01

    @@ A simple design procedure is used to generate photonic crystal fibers (PCFs) with ultra-flattened chromatic dispersion.Only four parameters are required, which not only considerably saves the computing time,but also distinctly reduces the air-hole quantity.The influence of the air-hole diameters of each ring of hexagonal PCFs (H-PCF, including 1-hole-missing and 7-hole-missing H-PCFs), circular PCFs (C-PCF),square PCFs (S-PCF), and octagonal PCFs (O-PCF) is investigated through simulations.%A simple design procedure is used to generate photonic crystal fibers (PCFs) with ultra-flattened chromatic dispersion. Only four parameters are required, which not only considerably saves the computing time,but also distinctly reduces the air-hole quantity. The influence of the air-hole diameters of each ring of hexagonal PCFs (H-PCF, including 1-hole-missing and 7-hole-missing H-PCFs), circular PCFs (C-PCF),square PCFs (S-PCF), and octagonal PCFs (O-PCF) is investigated through simulations. Results show that regardless of the cross section structures of the PCFs, the 1st ring air-hole diameter has the greatest influence on the dispersion curve followed by that of the 2nd ring. The 3rd ring diameter only affects the dispersion curve within longer wavelengths, whereas the 4th and 5th rings have almost no influence on the dispersion curve. The hole-to-hole pitch between rings changes the dispersion curve as a whole.Based on the simulation results, a procedure is proposed to design PCFs with ultra-flattened dispersion.Through the adjustment of air-hole diameters of the inner three rings and hole-to-hole pitch, a flattened dispersion of 0±0.5 ps/(nm·km) within a wavelength range of 1.239-2.083 μm for 5-ring 1-hole -missing H-PCF, 1.248-1.992μm for 5-ring C-PCF, 1.237-2.21 μm for 5-ring S-PCF, 1.149-1.926μgm for 5-ring O-PCF, and 1.294-1.663μm for 7-hole-missing H-PCF is achieved.

  5. Application of chitosan/polyacrylamide nanofibres for removal of chromate and phosphate in water

    Science.gov (United States)

    Nthumbi, Richard M.; Catherine Ngila, J.; Moodley, Brenda; Kindness, Andrew; Petrik, Leslie

    Water pollution is an intractable environmental problem in South Africa. Management of the water resource is vital in order to address the water scarcity issues. Research on remediation of contaminated water has focused mainly on the removal of heavy metals such as Pb, Cd, Zn, Hg and Cu and neglected other inorganic pollutants. In this work we focus on the removal of anions, namely chromate and phosphate. Chromium is extensively used in the textile, leather and metallurgy industries and contaminates surface water and groundwater when inadequately treated industrial effluents are discharged. Chromium has been associated with irregular sugar metabolism, nosebleeds and ulcers, and it is also carcinogenic. The phosphate ion is an essential micronutrient responsible for healthy plant growth. However, excess phosphate intake stimulates rapid growth of photosynthetic algae and cyanobacteria, resulting in eutrophication. This phenomenon (algal bloom) causes other organisms to die due to reduced oxygen in the water. In order to offer remediation measures, this study reports the use of electrospun nanofibres for the removal of chromate and phosphate anions. Adsorption experiments were carried out using nanofibres electrospun from chitosan and polyacrylamide polymer blends, cross-linked with glutaraldehyde. Quantification of chromium was done using ICP-OES while UV-Vis spectrophotometry was used for the determination of phosphates. Batch adsorption experiments were done to determine optimum adsorption parameters such as pH, contact time, temperature and initial analyte concentration. Removal of the ions using a flow-adsorption technique through a micro-column was performed. The experimental data obtained were analysed using Langmuir and Freundlich models to study the adsorption mechanisms. The nanofibres had an adsorption capacity for Cr(VI) and PO43- of 0.26 mg g-1 and 392 mg g-1, respectively, and removal efficiencies of 93% and 97.4%, in the same order, in synthetic water

  6. Size distribution of chromate paint aerosol generated in a bench-scale spray booth.

    Science.gov (United States)

    Sabty-Daily, Rania A; Hinds, William C; Froines, John R

    2005-01-01

    Spray painters are potentially exposed to aerosols containing hexavalent chromium [Cr(VI)] via inhalation of chromate-based paint sprays. Evaluating the particle size distribution of a paint spray aerosol, and the variables that may affect this distribution, is necessary to determine the site and degree of respiratory deposition and the damage that may result from inhaled Cr(VI)-containing paint particles. This study examined the effect of spray gun atomization pressure, aerosol generation source and aerosol aging on the size distribution of chromate-based paint overspray aerosols generated in a bench-scale paint spray booth. The study also determined the effect of particle bounce inside a Marple personal cascade impactor on measured size distributions of paint spray aerosols. Marple personal cascade impactors with a modified inlet were used for sample collection. The data indicated that paint particle bounce did not occur inside the cascade impactors sufficiently to affect size distribution when using uncoated stainless steel or PVC substrate sampling media. A decrease in paint aerosol mass median aerodynamic diameter (MMAD) from 8.2 to 7.0 mum was observed as gun atomization pressure increased from 6 to 10 psi. Overspray aerosols were sampled at two locations in the spray booth. A downstream sampling position simulated the exposure of a worker standing between the painted surface and exhaust, a situation encountered in booths with multiple workers. The measured mean MMAD was 7.2 mum. The distance between the painted surface and sampler was varied to sample oversprays of varying ages between 2.8 and 7.7 s. Age was not a significant factor for determining MMAD. Overspray was sampled at a 90 degrees position to simulate a worker standing in front of the surface being painted with air flowing to the worker's side, a common situation in field applications. The resulting overspray MMAD averaged 5.9 mum. Direct-spray aerosols were sampled at ages from 5.3 to 11.7 s

  7. Leaching from CCA-Treated Wood into Soils: Preliminary PIXE Studies

    Science.gov (United States)

    Kelly, R. F.; Kravchenko, I. I.; Kuharik, J. C.; Van Rinsvelt, H. A.; Dunnam, F. E.; Huffman, J.

    2003-08-01

    Widespread use of chromated copper arsenate (CCA) as a wood preservative has led to increasing public concern regarding possible toxic contamination of areas surrounding CCA-treated structures, e.g., decks, playground equipment, etc. Appreciable leaching of arsenic, chromium, and copper into soils adjacent to such structures has been demonstrated via standard techniques of analytical chemistry. The advantages of PIXE [rapid analysis, quick sample turnover, possible lower cost] suggest its application to this area of interest. PIXE studies in our laboratory of CCA-contaminated soil samples show good agreement with previous analyses of As, Cu, Cr, and other heavy-elemental content, with some variability in diffusion rates.

  8. Electroleaching of Copper Waste with Recovery of Copper by Electrodialysis

    Directory of Open Access Journals (Sweden)

    Nuñez P.

    2013-04-01

    Full Text Available A new process to leach and recover copper from solid waste using electric fields was designed. The leaching with electro migration is presented as an alternative to traditional leaching. Preliminary data indicate that the copper ion migration is facilitated by using the electrical potential difference; therefore applying a potential difference in the processes of leaching facilitates the removal of copper. This is especially useful when mineral concentrations are very low. Different phenomena associated with transport of copper in solution are studied to generate a model able predict the state of the copper ion concentration in time. A kinetic model for the process was developed and fitted very well the experimental data.

  9. Chromatic aberration and the roles of double-opponent and color-luminance neurons in color vision.

    Science.gov (United States)

    Vladusich, Tony

    2007-03-01

    How does the visual cortex encode color? I summarize a theory in which cortical double-opponent color neurons perform a role in color constancy and a complementary set of color-luminance neurons function to selectively correct for color fringes induced by chromatic aberration in the eye. The theory may help to resolve an ongoing debate concerning the functional properties of cortical receptive fields involved in color coding.

  10. Chromatic and Wavefront Aberrations: L-, M- and S-cone Stimulation with Typical and Extreme Retinal Image Quality

    OpenAIRE

    Autrusseau, Florent; THIBOS, LARRY; Shevell, Steven

    2011-01-01

    The first physiological process influencing visual perception is the optics of the eye. The retinal image is affected by diffraction at the pupil and several kinds of optical imperfections. A model of the eye (Thibos & Bradley, 1999), which takes account of pupil aperture, chromatic aberration and wavefront aberrations, was used to determine wavelength-dependent point-spread functions, which can be convolved with any stimulus specified by its spectral distribution of light at each point. The ...

  11. 100-D Area In Situ Redox Treatability Test for Chromate-Contaminated Groundwater: FY 1998 Year-End Report

    Energy Technology Data Exchange (ETDEWEB)

    Williams, M.D.; Vermeul, V.R.; Szecsody, J.E.; Fruchter, J.S.; Cole, C.R.

    1999-04-15

    A treatability test was conducted for the In Situ Redox Manipulation (ISRM) technology at the US Department of Energy's Hanford, Washington 100D Area. The target contaminant was dissolved chromate [Cr(VI)] in groundwater. The ISRM technology involves creating a permeable subsurface treatment zone to reduce mobile chromate in groundwater to an insoluble form. The ISRM permeable treatment zone is created by reducing ferric iron [Fe(III)] to ferrous iron [Fe(II)] within the aquifer sediments. This is accomplished by injecting aqueous sodium dithionite into the aquifer and withdrawing the reaction products. The goal of the treatability test was to create a linear ISRM barrier by injecting sodium dithionite into five wells. Well installation and site characterization activities began in the spring of 1997. The first dithionite injection took place in September 1997. The results of this first injection were monitored through the spring of 1998; the remaining four dithionite injections were carried out in May through July of 1998. These five injections created a reduced zone in the Hanford unconfined aquifer 150 feet in length (perpendicular to groundwater flow) by 50 feet wide. The reduced zone extended over the thickness of the unconfined zone, which is approximately 15 feet. Analysis of recent groundwater sampling events shows that the concentrations of chromate [Cr(VI)] in groundwater in the reduced zone have been decreased from starting concentrations of approximately 900 ppb to below analytical detection limits (<7 ppb). Chromate concentrations are also declining in some downgradient monitoring wells. Laboratory analysis of iron in the soil indicates that the barrier should remain in place for approximately 20 to 25 years. These measurements will be confirmed by analysis of sediment cores in FY 1999.

  12. KEY COMPARISON: EUROMET Project 666, EUROMET-PR.S1 Final Report: Intercomparison of chromatic dispersion reference fibres

    Science.gov (United States)

    Morel, Jacques

    2006-01-01

    The calibration of the chromatic dispersion properties of single-mode fibres is of critical importance for a proper optimization of optical fibre communication systems. Although extensive analyses of the commonly used calibration techniques were already performed by some NMIs, no large scale interlaboratory comparisons that could be used as a basis for the MRA existed at this time. The aim of this project was to perform a comparison of chromatic dispersion measurements that were carried out on four of the most commonly used fibre types, namely G652, G653, G655-TeraLight and G655-Leaf. This intercomparison was also registered as a supplementary comparison (Euromet-PR-S1) and will serve as a basis for the review of the CMC entries on chromatic dispersion. This intercomparison addressed the calibration of the three relevant quantities, namely the chromatic dispersion, the zero dispersion wavelength and the dispersion slope. All laboratories used quite similar equipment, but applied very different measurement strategies and data processing techniques. Very good agreement was found between the results provided by most of the participants. One laboratory obtained results with more significant deviations, probably due to a problem in its measurement setup. The results of this laboratory have been analyzed in this report, but have not been used for the determination of the mean value of the reported quantities. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EUROMET, according to the provisions of the Mutual Recognition Arrangement (MRA).

  13. Fixation Property of Copper Triazole Wood Preservatives

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    According to AWPA E11-2006 standard,copper fixation rates of several copper-based formulations,such as ammoniacal copper,amine copper,and ammoniacal-ethanolamine copper,as well as alkaline copper quaternary(ACQ),were tested and compared in this paper.And the fixation rates of tebuconazole(TEB) and propiconazole(PPZ) in several formulations,such as copper azole,emulsified type and solvent type,were also compared.The determination of copper content in the leachate was analyzed by atomic absorption spectrom...

  14. Studies of copper transport in mammalian cells using copper radioisotopes

    Energy Technology Data Exchange (ETDEWEB)

    Camakaris, J.; Voskoboinik, I.; Brooks, H.; Greenough, M. [University of Melbourne, Parkville, VIC (Australia). Department of Genetics; Smith, S. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia). Radiopharmaceuticals Division; Mercer, J. [Deakin University, Clayton, VIC (Australia). Centre of Cellular and Molecular Biology

    1998-12-31

    The trace element copper poses a major problem for all organisms. It is essential as a number of vital enzymes require it. Copper deficiency can lead to neurological disorders, osteoporosis and weakening of arteries. However Cu is also highly toxic and homeostatic mechanisms have evolved to maintain Cu at levels which satisfy requirements but do not cause toxicity. Toxicity is mediated by the oxidative capacity of Cu and its ability to generate toxic free radicals. There are several acquired and inherited diseases due to either Cu toxicity or Cu deficiency. The study of these diseases facilitates identification of genes and proteins involved in copper homeostasis, and this in turn will provide rational therapeutic approaches. Using the copper radioisotopes {sup 64}Cu (t1/2 = 12.8 hr) and {sup 67}Cu (t1/2 = 61 hr) we have developed a number of systems for studying copper transport in mammalian cells. These include investigation of copper uptake, copper efflux and ligand blot assays for Cu-binding proteins. Our studies have focused on Menkes disease which is an inherited and usually lethal copper deficiency disorder in humans. We have demonstrated that the Menkes protein is directly involved as a copper efflux pump in mammalian cells. Using cells overexpressing the Menkes protein we have provided the first biochemical evidence that this functions as a Cu translocating (across the membrane) P-type ATPase (Voskoboinik et al., FEBS Letters, in press). These studies were carried out using purified plasma membrane vesicles. We are now carrying out structure- function studies on this protein using targeted mutations and assaying using the radiocopper vesicle assay. Recently we have commenced studies on the role of amyloid precursor protein (APP) in copper transport and relationship of this to Alzheimers disease

  15. Assessment of chronic wounds by three-dimensional optical imaging based on integrating geometrical, chromatic, and thermal data.

    Science.gov (United States)

    Barone, S; Paoli, A; Razionale, A V

    2011-02-01

    Chronic wounds represent a particular debilitating health care problem, mainly affecting elderly people. A full and correct diagnosis of tissue damage should be carried out considering both dimensional, chromatic, and thermal parameters. A great variety of methods have been proposed with the aim of producing objective assessment of skin lesions, but none of the existing technologies seem to be robust enough to work for all ulcer typologies. This paper describes an innovative and non-invasive system that allows the automatic measurement of non-healing chronic wounds. The methodology involves the integration of a three-dimensional (3D) optical scanner, based on a structured light approach, with a thermal imager. The system enables the acquisition of geometrical data, which are directly related to chromatic and temperature patterns through a mapping procedure. Damaged skin areas are detected by combining visible and thermal imaging. This approach allows for the automatic measurement of extension and depth of ulcers, even in the absence of significant and well-defined chromatic patterns. The proposed technology has been tested in the measurement of ulcers on human legs. Clinical tests have demonstrated the effectiveness of this methodology in supporting medical experts for the assessment of chronic wounds. PMID:21428152

  16. Coupling of cerebral blood flow and oxygen metabolism is conserved for chromatic and luminance stimuli in human visual cortex.

    Science.gov (United States)

    Leontiev, Oleg; Buracas, Giedrius T; Liang, Christine; Ances, Beau M; Perthen, Joanna E; Shmuel, Amir; Buxton, Richard B

    2013-03-01

    The ratio of the changes in cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO(2)) during brain activation is a critical determinant of the magnitude of the blood oxygenation level dependent (BOLD) response measured with functional magnetic resonance imaging (fMRI). Cytochrome oxidase (CO), a key component of oxidative metabolism in the mitochondria, is non-uniformly distributed in visual area V1 in distinct blob and interblob regions, suggesting significant spatial variation in the capacity for oxygen metabolism. The goal of this study was to test whether CBF/CMRO(2) coupling differed when these subpopulations of neurons were preferentially stimulated, using chromatic and luminance stimuli to preferentially stimulate either the blob or interblob regions. A dual-echo spiral arterial spin labeling (ASL) technique was used to measure CBF and BOLD responses simultaneously in 7 healthy human subjects. When the stimulus contrast levels were adjusted to evoke similar CBF responses (mean 65.4% ± 19.0% and 64.6% ± 19.9%, respectively for chromatic and luminance contrast), the BOLD responses were remarkably similar (1.57% ± 0.39% and 1.59% ± 0.35%) for both types of stimuli. We conclude that CBF-CMRO(2) coupling is conserved for the chromatic and luminance stimuli used, suggesting a consistent coupling for blob and inter-blob neuronal populations despite the difference in CO concentration. PMID:23238435

  17. Integrated iinvestiigatiion on the productiion and fate of organo-Cr(III) compllexes from miicrobiiall reductiion of chromate

    Energy Technology Data Exchange (ETDEWEB)

    Luying Xun; Clark, Sue; Peyton, Brent; Yonge, David

    2004-03-17

    Chromium contamination exists at 13 of the 18 Department of Energy facilities studied; microbial reduction to form insoluble trivalent Cr, Cr(III), is a potential treatment for such sites. In our prior research on Cr(VI) reduction, we have discovered that soluble organo-Cr(III) complexes are likely formed and then, perhaps, further transformed to insoluble Cr(III) precipitates. The production of organo-Cr(III) complexes from chromate reduction is documented in eukaryotic systems because the stable DNA-Cr adducts are mutagenic. However, the formation of soluble organo-Cr(III) complexes from microbial reduction of chromate has only recently been discovered, bringing up the necessity for investigating the significance of the soluble complexes in Cr bioremediation. The proposed research is aimed at: (1) characterizing the scope and extent of organo-Cr(III) complex formation by chromate reducing microorganisms, (2) evaluating cellular components that can potentially form organo-Cr(III) complexes, (3) addressing the stability and biodegradability of these organo-CR(III) complexes, and (4) assessing the fate and transport of these compounds in soils. The results will provide scientific guidance on whether organo-Cr(III) should be considered during application of Cr bioremediation. The information will also help establish a more complete biogeochemical cycle for Cr, which is currently lacking organo-Cr(III) complexes.

  18. In silico analysis of bacterial arsenic islands reveals remarkable synteny and functional relatedness between arsenate and phosphate

    Directory of Open Access Journals (Sweden)

    Christopher eRensing

    2013-11-01

    Full Text Available In order to construct a more universal model for understanding the genetic requirements for bacterial AsIII oxidation, an in silico examination of the available sequences in the GenBank was assessed and revealed 21 conserved 5-71 kb arsenic islands within phylogenetically diverse bacterial genomes. The arsenic islands included the AsIII oxidase structural genes aioBA, ars operons (e.g. arsRCB which code for arsenic resistance, and pho, pst, and phn genes known to be part of the classical phosphate stress response and that encode functions associated with regulating and acquiring organic and inorganic phosphorus. The regulatory genes aioXSR were also an island component, but only in Proteobacteria and orientated differently depending on whether they were in α-Proteobacteria or β-/γ-Proteobacteria. Curiously though, while these regulatory genes have been shown to be essential to AsIII oxidation in the Proteobacteria, they are absent in most other organisms examined, inferring different regulatory mechanism(s yet to be discovered. Phylogenetic analysis of the aio, ars, pst and phn genes revealed evidence of both vertical inheritance and horizontal gene transfer. It is therefore likely the arsenic islands did not evolve as a whole unit but formed independently by acquisition of functionally related genes and operons in respective strains. Considering gene synteny and structural analogies between arsenate and phosphate, we presumed that these genes function together in helping these microbes to be able to use even low concentrations of phosphorus needed for vital functions under high concentrations of arsenic, and defined these sequences as the arsenic islands.

  19. Behavioural and Physiological Responses of Gammarus pulex Exposed to Cadmium and Arsenate at Three Temperatures: Individual and Combined Effects

    Science.gov (United States)

    Vellinger, Céline; Felten, Vincent; Sornom, Pascal; Rousselle, Philippe; Beisel, Jean-Nicolas; Usseglio-Polatera, Philippe

    2012-01-01

    This study aimed at investigating both the individual and combined effects of cadmium (Cd) and arsenate (AsV) on the physiology and behaviour of the Crustacean Gammarus pulex at three temperatures (5, 10 and15°C). G. pulex was exposed during 96 h to (i) two [Cd] alone, (ii) two [AsV] alone, and (iii) four combinations of [Cd] and [AsV] to obtain a complete factorial plane. After exposure, survival, [AsV] or [Cd] in body tissues, behavioural (ventilatory and locomotor activities) and physiological responses (iono-regulation of [Na+] and [Cl−] in haemolymph) were examined. The interactive effects (antagonistic, additive or synergistic) of binary mixtures were evaluated for each tested temperature using a predictive model for the theoretically expected interactive effect of chemicals. In single metal exposure, both the internal metal concentration in body tissues and the mortality rate increased along metallic gradient concentration. Cd alone significantly impaired both [Na+] and [Cl−] while AsV alone had a weak impact only on [Cl−]. The behavioural responses of G. pulex declined with increasing metal concentration suggesting a reallocation of energy from behavioural responses to maintenance functions. The interaction between AsV and Cd was considered as ‘additive’ for all the tested binary mixtures and temperatures (except for the lowest combination at 10°C considered as “antagonistic”). In binary mixtures, the decrease in both ventilatory and locomotor activities and the decline in haemolymphatic [Cl−] were amplified when respectively compared to those observed with the same concentrations of AsV or Cd alone. However, the presence of AsV decreased the haemolymphatic [Na+] loss when G. pulex was exposed to the lowest Cd concentration. Finally, the observed physiological and behavioural effects (except ventilation) in G. pulex exposed to AsV and/or Cd were exacerbated under the highest temperature. The discussion encompasses both the toxicity

  20. Redox state and energetic equilibrium determine the magnitude of stress in Hydrilla verticillata upon exposure to arsenate.

    Science.gov (United States)

    Srivastava, Sudhakar; Suprasanna, Penna; D'Souza, Stanislaus Francis

    2011-10-01

    Arsenic (As) is a potential hazard to plants' health, however the mechanisms of its toxicity are yet to be properly understood. To determine the impact of redox state and energetic in stress imposition, plants of Hydrilla verticillata (L.f.) Royle, which are known to be potential accumulator of As, were exposed to 100 and 500 μM arsenate (AsV) for 4 to 96 h. Plants demonstrated significant As accumulation with the maximum being at 500 μM after 96 h (568 μg g(-1) dry weight, dw). The accumulation of As led to a significant increase in the level of reactive oxygen species, nitric oxide, carbonyl, malondialdehyde, and percentage of DNA degradation. In addition, the activity of pro-oxidant enzymes like NADPH oxidase and ascorbate oxidase also showed significant increases. These parameters collectively indicated oxidative stress, which in turn caused an increase in percentage of cell death. These negative effects were seemingly linked to an altered energetic and redox equilibrium [analyzed in terms of ATP/ADP, NADH/NAD, NADPH/NADP, reduced glutathione/oxidized glutathione, and ascorbate/dehydroascobate ratios]. Although there was significant increase in the levels of phytochelatins, the As chelating ligands, a large amount of As was presumably present as free ion particularly at 500 μM AsV, which supposedly produced toxic responses. In conclusion, the study demonstrated that the magnitude of disturbance to redox and energetic equilibrium of plants upon AsV exposure determines the extent of toxicity to plants.