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Sample records for investigations targeting chromium

  1. RESULTS FROM RECENT SCIENCE AND TECHNOLOGY INVESTIGATIONS TARGETING CHROMIUM IN THE 100D AREA HANFORD SITE WASHINGTON USA

    Energy Technology Data Exchange (ETDEWEB)

    PETERSEN SW; THOMPSON KM; TONKIN MJ

    2009-12-03

    Sodium dichromate was used in Hanford's 100D Area during the reactor operations period of 1950 to 1964 to retard corrosion in the reactor cooling systems. Some of the sodium dichromate was released to the environment by spills and/or leaks from pipelines used to deliver the chemical to water treatment plants in the area. As a result, hexavalent chromium [Cr(VI)] has migrated through the vadose zone to the groundwater and contaminated nearly 1 km{sup 2} of groundwater to above the drinking water standard of 48 {micro}g/L. Three technology tests have recently been completed in this area to characterize the source area of the plumes and evaluate alternative methods to remove Cr(VI) from groundwater. These are (1) refine the source area of the southern plume; (2) test electrocoagulation as an alternative groundwater treatment technology; and (3) test the ability to repair a permeable reactive barrier by injecting micron or nanometer-size zero-valent iron (ZVI). The projects were funded by the US Department of Energy as part of a program to interject new technologies and accelerate active cleanup. Groundwater monitoring over the past 10 years has shown that Cr(VI) concentrations in the southern plume have not significantly diminished, strongly indicating a continuing source. Eleven groundwater wells were installed in 2007 and 2008 near a suspected source area and monitored for Cr(VI) and groundwater levels. Interpretation of these data has led to refinement of the source area location to an area of less than 1 hectare (ha, 2.5 acres). Vadose zone soil samples collected during drilling did not discover significant concentrations of Cr(VI), indicating the source is localized, with a narrow wetted path from the surface to the water table. Electrocoagulation was evaluated through a pilot-scale treatability test. Over 8 million liters of groundwater were treated to Cr(VI) concentrations of {le}20 {micro}g/L. The test determined that this technology has the potential to

  2. Chromium

    Science.gov (United States)

    ... Office of Dietary Supplements Health Professional Other Resources Chromium Dietary Supplement Fact Sheet Have a question? Ask ... of chromium Chromium and Healthful Diets References Disclaimer Chromium: What is it? Chromium is a mineral that ...

  3. Roentgenoelectronic investigation into oxidation of iron-chromium and iron-chromium-nickel alloys

    International Nuclear Information System (INIS)

    Akimov, A.G.; Rozenfel'd, I.L.; Kazanskij, L.P.; Machavariani, G.V.

    1978-01-01

    Kinetics of iron-chromium and iron-chromium-nickel alloy oxidation (of the Kh13 and Kh18N10T steels) in oxygen was investigated using X-ray electron spectroscopy. It was found that according to X-ray electron spectra chromium oxidation kinetics in the iron-chromium alloy differs significantly from oxidation kinetics of chromium pattern. Layer by layer X-ray electron analysis showed that chromium is subjected to a deeper oxidation as compared to iron, and accordingly, Cr 2 O 3 layer with pure iron impregnations is placed between the layer of mixed oxide (Fe 3 O 4 +Cr 2 O 3 ) and metal. A model of the iron-chromium alloy surface is suggested. The mixed oxide composition on the steel surface is presented as spinel Fesub(2+x)Crsub(1-x)Osub(y)

  4. Synthesis of chromium (V) complex in deuterated propanediol for a target with ``frozen'' polarisation of deuterons

    Science.gov (United States)

    Bunyatova, E. I.; Bubnov, N. N.

    1987-02-01

    A deuteron polarized frozen spin target was developed. To reach higher deuteron content and maximum polarization, the chromium (V) complex with ligands on the basis of fully deuterated propanediol-1,2 was synthesized. The synthesis and the EPR investigation is described. The research has been performed at the Laboratory of Nuclear Problems, JINR.

  5. Synthesis of chromium (V) complex on the basis of deuterated ethanediol for a polarized deuteron target

    Energy Technology Data Exchange (ETDEWEB)

    Bunyatova, E.I.; Bubnov, N.N. (Joint Inst. for Nuclear Research, Moscow (USSR). Lab. of Nuclear Problems)

    1984-01-15

    To develop a target with polarised deuterons the chromium (V) complex with deuterated ethanediol ligands was synthesized. The electron paramagnetic resonance (EPR) spectra were employed to determine the concentration and g-factor of the complex. The procedure to obtain the chromium (V) complex with partly deuterated ethanediol ligands is also discussed.

  6. Synthesis of chromium (V) complex on the basis of deuterated ethanediol for a polarized deuteron target

    Science.gov (United States)

    Bunyatova, E. I.; Bubnov, N. N.

    1984-01-01

    To develop a target with polarised deuterons the chromium (V) complex with deuterated ethanediol ligands was synthesized. The electron paramagnetic resonance (EPR) spectra were employed to determine the concentration and g-factor of the complex. The procedure to obtain the chromium (V) complex with partly deuterated ethanediol ligands is also discussed.

  7. Investigations on the fracture toughness of austempered ductile iron alloyed with chromium

    Energy Technology Data Exchange (ETDEWEB)

    Rao, P. Prasad; Putatunda, Susil K

    2003-04-15

    An investigation was carried out to examine the influence of chromium content on the plane strain fracture toughness of austempered ductile iron (ADI). ADIs containing 0, 0.3 and 0.5 wt.% chromium were austempered over a range of temperatures to produce different microstructures. The microstructures were characterized by optical microscopy and X-ray diffraction. Plane strain fracture toughness of all these materials was determined and correlated with microstructure and chromium content. The chromium content was found to influence the fracture toughness through its influence on the processing window. Since the chromium addition shifts the processing window to shorter durations, the higher chromium alloys at higher austempering temperatures tend to fall outside of the processing window, resulting in less than optimum microstructure and inferior fracture toughness. A small chromium addition of 0.3 wt.% was found to be beneficial for the fracture toughness of ADI.

  8. An investigation of the bioaccumulation of chromium and uranium ...

    African Journals Online (AJOL)

    KONANANI

    2013-11-13

    Nov 13, 2013 ... heavy metal such as chromium (Cr) and uranium (U) which poses enormous threat to the environment even at small quantity. The study focuses mainly on bioaccumulation of Cr and U in soil by Cynodon ... bioaccumulate toxic metals Cr and U from the mine tailings making them potential phytoremediation.

  9. An investigation of the bioaccumulation of chromium and uranium ...

    African Journals Online (AJOL)

    Mine waste, including tailings is generally outlined as one of the largest environmental concern which faces defunct mines in South Africa and New Union Gold Mine is no exception. These tailing contain heavy metal such as chromium (Cr) and uranium (U) which poses enormous threat to the environment even at small ...

  10. Synthesis of chromium (V) complex in deuterated propanediol for a target with ''frozen'' polarization of deuterons

    Energy Technology Data Exchange (ETDEWEB)

    Bunyatova, E.I.; Bubnov, N.N.

    1987-02-15

    A deutron polarized frozen spin target was developed. To reach higher deuteron content and maximum polarization, the chromium (V) complex with ligands on the basis of fully deuterated propanediol-1,2 was synthesized. The synthesis and the EPR investigation is described. The research has been performed at the Laboratory of Nuclear Problems, JINR.

  11. EXPERIMENTAL INVESTIGATION ON CHROMIUM(VI REMOVAL FROM AQUEOUS SOLUTION USING ACTIVATED CARBON RESORCINOL FORMALDEHYDE XEROGELS

    Directory of Open Access Journals (Sweden)

    Eghe A. Oyedoh

    2016-10-01

    Full Text Available The adsorption of chromium(VI metal ion in aqueous solutions by activated carbon resorcinol formaldehyde xerogels (ACRF was investigated. The results showed that pore structure, surface area and the adsorbent surface chemistry are important factors in the control of the adsorption of chromium(VI metal ions. The isotherm parameters were obtained from plots of the isotherms and from the application of Langmuir and Freundlich Isotherms. Based on regression analysis, the Langmuir isotherm model was the best fit. The maximum adsorption capacity of ACRF for chromium (VI was 241.9 mg/g. The pseudo-second-order kinetic model was the best fit to the experimental data for the adsorption of chromium metal ions by activated carbon resorcinol formaldehyde xerogels. The thermodynamics of Cr(VI ions adsorption onto ACRF was a spontaneous and endothermic process.

  12. Application of the Positron Annihilation Spectroscopy for Chromium Effect Investigation in Binary Fe-Cr Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sojak, S.; Krsjak, V.; Slugen, V.; Stancek, S.; Petriska, M.; Vitazek, K.; Stacho, M. [Department of Nuclear Physics and Technology, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia)

    2008-07-01

    Positron annihilation spectroscopy (PAS) is one of the non-destructive techniques applied with advantage for evaluation of the radiation treated materials microstructure. In this work, the PAS was used for study of different Fe-Cr alloys implanted by ions of helium. Investigation was focused on the chromium effect and the radiation defects resistance. In particular, the vacancy type defects (mono-vacancies, vacancy clusters) have been studied. The results show that the specific content of chromium has important influence on the size and distribution of induced defects. (authors)

  13. Chromium allergy

    DEFF Research Database (Denmark)

    Hansen, M B; Johansen, J D; Menné, Torkil

    2003-01-01

    Most studies investigating chromium allergy have been performed with Cr(VI). However, real exposure to chromium from leather products includes both Cr(III) and Cr(VI). We have determined and compared the minimum elicitation threshold (MET) concentration for Cr(III) and Cr(VI) in Cr......(III) was concluded to play an important role in chromium allergy, because Cr(III) and Cr(VI) were both capable of eliciting eczema at low concentrations. Rather than regarding chromium dermatitis as a result of Cr(VI) allergy alone, it may be more correct to consider it as a result of a combined Cr(III) and Cr...

  14. AQUIFER TESTING AND REBOUND STUDY IN SUPPORT OF THE 100-H DEEP CHROMIUM INVESTIGATION

    Energy Technology Data Exchange (ETDEWEB)

    SMOOT JL

    2010-11-05

    The 100-HR-3 Groundwater Operable Unit (OU) second Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) 5-year review (DOEIRL-2006-20, The Second CERCLA Five-Year Review Report for the Hanford Site) set a milestone to conduct an investigation of deep hexavalent chromium contamination in the sediments of the Ringold upper mud (RUM) unit, which underlies the unconfined aquifer in the 100-H Area. The 5-year review noted that groundwater samples from one deep well extending below the aquitard (i.e., RUM) exceeded both the groundwater standard of 48 parts per billion (ppb) (Ecology Publication 94-06, Model Toxics Control Act Cleanup Statute and Regulation) and the federal drinking water standard of 100 {mu}g/L for hexavalent chromium. The extent of hexavalent chromium contamination in this zone is not well understood. Action 12-1 from the 5-year review is to perform additional characterization of the aquifer below the initial aquitard. Field characterization and aquifer testing were performed in the Hanford Site's 100-H Area to address this milestone. The aquifer tests were conducted to gather data to answer several fundamental questions regarding the presence of the hexavalent chromium in the deep sediments of the RUM and to determine the extent and magnitude of deeper contamination. The pumping tests were performed in accordance with the Description of Work for Aquifer Testing in Support of the 100-H Deep Chromium Investigation (SGW-41302). The specific objectives for the series of tests were as follows: (1) Evaluate the sustainable production of the subject wells using step-drawdown and constant-rate pumping tests. (2) Collect water-level data to evaluate the degree of hydraulic connection between the RUM and the unconfined (upper) aquifer (natural or induced along the well casing). (3) Evaluate the hydraulic properties of a confined permeable layer within the RUM.; (4) Collect time-series groundwater samples during testing to

  15. Investigation of the removal of chromium (VI by Nanocomposites Chitosan-tragacanth solution from aqueous solution

    Directory of Open Access Journals (Sweden)

    Adel Almasi Nahnaji

    2016-03-01

    Full Text Available Background: The aim of this study was to investigate the removal of chromium (VI by Nanocomposites Chitosan-tragacanth solution from aqueous solution. Methods: In this study, chitosan-tragacanth nanocomposites were synthesized and analyzed by electron microscopy (SEM, (TEM and Fourier transform spectroscopy (FT-IR for the size and shape of the surface. The nano-composite of chitosan-tragacanth, for the adsorption of chromium (VI in aqueous solution was used as adsorbent. Results: The optimum conditions with multiple experiments to enhance the absorption were evaluated. The highest absorption of Cr (VI was occurred in the adsorbent dosage of 0.2 g, 8 ppm concentration of chromium ions, the pH=6 and also retention time of 50 min; in 298 ˚K temperature. After determining optimal conditions of adsorption, isotherms equations and study and thermodynamic parameters were applied. Adsorption process of chromium (VI on nano-composite chitosan - Tragacanth was conformed with Temkin isotherm. Conclusion: The thermodynamic parameters such as standard Gibbs free energy changes, changes in enthalpy and entropy changes in the standard showed that the adsorption process of Cr (VI is spontaneous and heating, and kinetics studies of models Lagergren, Ho , Alovich and intraparticle is used, the results show that the adsorption kinetics follows the pseudo-second order.

  16. Chromium-nanodiamond coatings obtained by magnetron sputtering and their tribological properties

    Science.gov (United States)

    Atamanov, M. V.; Khrushchov, M. M.; Marchenko, E. A.; Shevchenko, N. V.; Levin, I. S.; Petrzhik, M. I.; Miroshnichenko, V. I.; Relianu, M. D.

    2017-07-01

    Peculiarities of structure, chemical and phase composition, micromechanical and tribological properties of chromium-based coatings obtained by magnetron-sputtering of composite and/or compacted chromium-nanodiamond targets have been investigated.

  17. Investigation on the structural and mechanical properties of anti-sticking sputtered tungsten chromium nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Tai-Nan [Chemical Engineering Division, Institute of Nuclear Energy Research, Taiwan, ROC (China); Han, Sheng [Department of Leisure and Recreation Management, National Taichung University of Science and Technology, Taiwan, ROC (China); Weng, Ko-Wei, E-mail: kowei@nqu.edu.tw [Department of Electronic Engineering, National Quemoy University, Taiwan, ROC (China); Lee, Chin-Tan [Department of Electronic Engineering, National Quemoy University, Taiwan, ROC (China)

    2013-02-01

    Tungsten chromium nitride (WCrN) thin films are prepared by dual-gun co-sputter process. As the surface coatings on the molding die for glass forming, WCrN films show less deterioration at high temperature than the conventional CrN coating. WCrN thin films are deposited via the reactive co-sputtering of Cr/W targets. The working pressure is kept at 2.66 Pa and the argon/nitrogen ratio is 10. Applied power of chromium is fixed and the applied power of tungsten is varied. Experimental results indicate that the atomic ratio of tungsten in the films increases with the applied power of tungsten. The dominant crystalline phase is chromium nitride when the tungsten target power is below 100 W, while tungsten nitride dominates in the film structure when the tungsten target power is beyond 200 W. A dense structure with much finer particles is developed as the tungsten power is 200 W. As the power is increased to 300 W, the particles become coarser in size. The film roughness exhibits a decreasing trend at low tungsten power and then increases as the tungsten power increased up to 300 and 400 W, presumably due to the phase change from chromium nitrides to tungsten nitrides. Further annealing of the WCrN thin films is simulated as the glass molding condition to check the anti-sticking property which is a critical requirement in molding die surface coating application. The WCrN thin film coating shows good anti-sticking property at 400 °C annealing when the tungsten target power is 200 W. - Highlights: ► WCrN films are deposited by dual sputtering of pure Cr and W targets. ► The covalent bonding character of WCrN films explains the difference in hardness. ► WCrN (200 W W-target-power/400 °C-annealing) exhibits the best anti-sticking performance.

  18. PALS investigation of chromium effect in ferritic/martensitic steels implanted with helium

    Energy Technology Data Exchange (ETDEWEB)

    Krsjak, Vladimir [Institute for Energy, Joint Research Centre of the European Commission, Petten (Netherlands); Slugen, Vladimir; Petriska, Martin; Veternikova, Jana [Slovak University of Technology, FEI, Bratislava (Slovakia); Sojak, Stanislav

    2009-11-15

    Chromium is an element with significant effect on the elevated temperature corrosion resistance and the low radiation induced void swelling. There were several studies carried out with regard to effect of Cr on the defect creation and stability[1,2], but this issue is not fully understood yet. This paper contributes to this research with the study of Fe-Cr binary alloys with different Cr content, implanted by helium by the use of cascade accelerator and investigated by conventional PALS set-up. Our measurements show that chromium plays a role in the formation of small vacancy clusters, affecting the size and distribution of these defects. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Dietary Chromium Supplementation for Targeted Treatment of Diabetes Patients with Comorbid Depression and Binge Eating

    Science.gov (United States)

    Brownley, Kimberly A.; Boettiger, Charlotte A.; Young, Laura; Cefalu, William T.

    2015-01-01

    Dietary chromium supplementation for the treatment of diabetes remains controversial. The prevailing view that chromium supplementation for glucose regulation is unjustified has been based upon prior studies showing mixed, modest-sized effects in patients with type 2 diabetes (T2DM). Based on chromium's potential to improve insulin, dopamine, and serotonin function, we hypothesize that chromium has a greater glucoregulatory effect in individuals who have concurrent disturbances in dopamine and serotonin function – that is, complex patients with comorbid diabetes, depression, and binge eating. We propose, as suggested by the collective data to date, the need to go beyond the “one size fits all” approach to chromium supplementation and put forth a series of experiments designed to link physiological and neurobehavioral processes in the chromium response phenotype. PMID:25838140

  20. Progress in the chemistry of chromium(V) doping agents used in polarized target materials

    International Nuclear Information System (INIS)

    Krumpolc, M.; Hill, D.; Struhrmann, H.B.

    1990-01-01

    We wish to report progress in two areas of the chromium (V)-based doping agents: Two commonly used chromium (V) complexes, I and II, have been synthesized in perdeuterated form (i.e., all hydrogens replaced by deuterium). They are sodium bis(2-ethyl-2-deuteroxy-butyrato)oxochromate(V)monodeuterate, IV, (acronym EDBA-Cr(V)), and sodium bis(2-deuteroxy-2-methylpropionato)oxochromate(V), III, (acronym DMPA-Cr(V)). A synthetic route leading to the preparation of stable, chromium(III)-free solutions of chromium(V) in diols (1,2-ethanediol/ethylene glycol/and 1,2-propanediol/propylene glycol/) has been outlined

  1. Investigation of the surface composition of electrodeposited black chromium by X-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Survilienė, S.; Češūnienė, A.; Jasulaitienė, V.; Jurevičiūtė, I.

    2015-01-01

    Highlights: • Black chromium electrodeposited from a Cr(III) bath is composed of oxide, hydroxide and metallic chromium. • Metallic phase is absent in black chromium electrodeposited from a Cr(III) + ZnO bath. • The near-surface layer is rich in hydroxides, whereas oxides of both metals predominate in the depth of the coatings. - Abstract: The paper reviews black chromium electrodeposited from a trivalent chromium bath containing ZnO as a second main component. The chemical compositions of the top layers of the black chromium coatings were studied by the X-ray photoelectron spectroscopy method. The surface of black chromium was found to be almost entirely covered with organic substances. To gain information on the state of each element in the deposit bulk, the layer-by-layer etching of the black chromium surface with argon gas was used. Analysis of XPS spectra has shown that the top layers of black chromium without zinc are composed of various Cr(III) components, organic substances and metallic Cr, whereas metallic Cr is almost absent in black chromium containing some amount of Zn(II) compounds. The ratios of metal/oxide phases were found to be 10/27 and 2/28 for black chromium without and with zinc, respectively. It has been determined that owing to the presence of ZnO in the Cr(III) bath, the percentage of metallic chromium is substantially reduced in black chromium which is quite important for good solar selective characteristics of the coating. The results confirm some of earlier observations and provide new information on the composition of the near-surface layers

  2. Investigation into rammed zircon masses on aluminium-chromium-phosphate bond for induction furnace lining

    International Nuclear Information System (INIS)

    Pastushkov, V.G.; Baronov, V.A.; Borisov, G.B.; Novoselov, G.P.; Klement'eva, V.S.; Filimonova, N.I.

    1978-01-01

    The physical and thermomechanical properties of packing zircon masses on aluminochromophosphate binders (ACPB), which are concentrated aqueous solutions of mixed aluminium and chromium phosphates, were investigated. The conditions of drying and annealing of zircon masses on ACPB and the solid-phase reaction with the mixed (U, Pu)O 2 nuclear fuel at 1500 deg C are described. The optimum composition of packing mass was determined: 95% zircon of fraction 0.06 - 3.0 mm, 5% refractory clay finer than 0.5 mm, and 7% ACPB with 1.5 g/cm 2 density. The mass is characterized by a high strength, and low porosity and water absorption. The packing zircon mass an ACPB is recommended for use in induction furnaces of apparatus for thermal unsealing of spent fuel elements of fast reactors

  3. Small-angle neutron scattering investigation of the nanostructure of ferritic-martensitic 12%-chromium steels

    Science.gov (United States)

    Bogdanov, S. G.; Goshchitskii, B. N.; Parkhomenko, V. D.; Leontieva-Smirnova, M. V.; Chernov, V. M.

    2014-01-01

    The nanostructure (nanoparticle distribution) of ferritic-martensitic 12%-chromium steels EK-181 (Fe-12Cr-2W-V-Ta-B) and ChS-139 (Fe-12Cr-2W-V-Ta-B-Nb-Mo) subjected to different modes of mechanical and heat treatments and neutron irradiation has been investigated using small-angle neutron scattering. The samples have been studied in the initial state and after neutron irradiation (IVV-2M reactor) at a temperature of 80°C with fluences of 1018, 1019, and 5 × 1019 cm-2 ( E ≥ 0.1 MeV). The nanostructure of the steels is characterized by precipitations of nanoparticles with two characteristic sizes of 1.0-1.5 and 7-8 nm. The dependence of the nanostructure parameters on the composition of the steels and on the conditions of heat treatment and irradiation has been discussed.

  4. Investigation of performance degradation of SOFC using chromium-containing alloy interconnects

    DEFF Research Database (Denmark)

    Beeaff, D.R.; Dinesen, A.; Hendriksen, Peter Vang

    2007-01-01

    of chromia-forming stainless steels can lead to the deposition of material at the triple phase boundary (TPB), a process known as chromium poisoning, which leads to a reduction in the electrochemical performance of the cell over time. Scaling was accomplished using aluminosilicate glass with 30wt. % Mg...

  5. Investigation of Apple Scum and Its Modification with Magnesium Chloride and Hydrogen Peroxide for Removal of Toxic Hexavalent Chromium from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    M. Noori Sepehr

    2014-12-01

    Full Text Available Introduction: Chromium is one of the heavy metals present in effluents produced from industrial activities and exists in the trivalent and hexavalent state. It is mentioned that hexavalent chromium has is more hazardous due to its carcinogenic properties. Due to its hazard, Cr(VI must be removed from wastewaters prior discharge into the environment. For this reason, the present aimed for removal of hexavalent chromium by Apple Scum and its modification with magnesium chloride and hydrogen peroxide. Material and Methods: Apple Scum was obtained from Galin Plan as waste materials. The Apple Scum was modified with 2M MgCl2 and 30% H2O2. Several experimental parameters such as solution pH (1-9, contact time (1-100 min, solution temperature (20-60oC, adsorbent dosage (2-10 g/L and initial chromium concentration (10-100 mg/L was investigated. All experiments were done in batch system. Results: The results of present work reveals that chromium removal efficiency was increased with increase in adsorbent dosage, contact time and initial chromium concentration, while decreased for increase in solution pH and temperature. Higher removal efficiency was observed at pH 1, 100 min contact time, 100 mg/L chromium concentration and 20oC temperature. At this optimal condition up to 90% of chromium was removed. In addition, the modification of Apple Scum leads to increase in chromium removal efficiency up to 98% for MgCl2 modified adsorbent and up to 95% forH2O2 modified one. Conclusion: The results of present work well demonstrate the waste Apple Scum for removal of hexavalent chromium and its sorption capacity will be improved in the case of modification with H2O2 and MgCl2.

  6. Investigation of alternative phosphating treatments for nickel and hexavalent chromium elimination

    International Nuclear Information System (INIS)

    Jazbinsek, Luiz Antonio Rossi

    2014-01-01

    The phosphating processes are widely used in industry as surface treatments for metals, especially for low thickness plates, improving the adhesion between the metallic surface and the paint coating, and increasing the durability of paint systems against corrosion attacks. The tricationic phosphates containing zinc, nickel and manganese are commonly applied on steel. There is much discussion about the replacement of nickel by another element in order to have an environmentally friendly phosphating process. Niobium as a replacement for nickel has been evaluated. The most significant environmental impacts of phosphating processes are related to the presence of nickel and hexavalent chromium used in the process, this last as a passivation treatment. Nickel and hexavalent chromium are harmful to human and environment leading to contamination of water and soil. In the present study phosphate layers containing zinc, manganese and niobium have been evaluated and characterized on galvanized steel, and the results were compared with phosphates containing zinc, manganese and nickel, or a bicationic phosphate layer with zinc and manganese. Although the use of hexavalent chromium is not recommended worldwide, it is still used in processes for sealing the porosity of phosphate layers. This element is carcinogenic and has been associated with various diseases. Due to the passivation characteristics of niobium, this study also evaluated the tricationic bath containing niobium ammonium oxalate as a passivation treatment. The results showed that it could act as a replacement for the hexavalent chromium. The results of the present study showed that formulations containing niobium are potential replacements for hexavalent chromium and similar corrosion protection was obtained for the phosphate containing nickel or that with niobium. The morphology observed by scanning electron microscopy, gravimetric tests, porosity and adhesion evaluation results indicated that the phosphate

  7. Technological investigations of ferritic chromium steels with extra low concentrations of carbon and nitrogen

    International Nuclear Information System (INIS)

    Mueller, E.

    1976-01-01

    Ferritic chromium steels with extra low concentrations of C and N were examined by the Strauss Test and by other methods. The results show that resistance against intergranular corrosion can be reached by titanium concentrations ten times higher than the sum of C and N concentrations, whereas stability against pitting corrosion can be achieved by adding 1.3 % Mo. On grounds of the excellent corrosion resistance these steels will be of interest in nuclear technology

  8. Experimental and theoretical investigation of the chromium-vanadium-antimony system

    Energy Technology Data Exchange (ETDEWEB)

    Regus, Matthias; Bensch, Wolfgang [Kiel Univ. (Germany). Inst. of Inorganic Chemistry; Polesya, Svitlana; Kuhn, Gerhard; Mankovsky, Sergiy; Ebert, Hubert [Muenchen Univ. (Germany). Dept. of Chemistry; Bauers, Sage R.; Johnson, David C. [Oregon Univ., Eugene, OR (United States). Dept. of Chemistry

    2017-03-01

    The binary compound V{sub 3}Sb (V{sub 2.64}Sb, V{sub 3}Sb and V{sub 3.24}Sb) was synthesized as thin multilayered films with varying V:Sb ratios. The V-content determines the crystallization temperature and it is highest for the film with the lowest amount of V. Ternary chromium-vanadium-antimony (Cr-V-Sb) films were prepared containing Cr from 10 to 51 at-% with the Sb content fixed to yield M{sub 3}Sb (M=Cr, V). In the as-deposited state the layers are already interdiffused which is most likely caused by the very low repeating unit thickness between 0.29 and 0.68 nm investigated by X-ray diffraction experiments. All ternary compounds crystallized from the amorphous state with crystallization temperatures depending more on the repeating unit thickness than on chemical composition. For most samples the simultaneous crystallization of the two phases M{sub 3}Sb (A15 structure type) and MSb is observed. The crystalline A15 compounds are only stable in a limited temperature range and decompose at elevated temperatures. Compared to the binary Cr-Sb system crystallization of the hexagonal phase MSb (M=Cr, V) occurs at remarkably higher temperatures, i.e. in the ternary system nucleation and crystallization of this phase is hindered. The chemical composition requires short-range composition fluctuations to nucleate the binary phase. The first principles total energy calculations using the spin-polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) method confirm the experimental observations concerning the concentration-dependent stability of different phases of the Cr-V-Sb system. For the ratio M:Sb=3:1 the system is preferably stabilized in the A15 crystal structure for all possible Cr and V concentrations, while an increase of Sb content up to M:Sb=2:1 results in the stabilization of the Ni{sub 2}In structure for almost all Cr concentrations. Only in the V-rich regime of the system the Heusler Ni{sub 2}MnAl-type structure was found to be energetically more preferable.

  9. Investigation of the influence of cementation of chromium onto aluminium on the characteristics of non-printing elements of an offset printing plate

    Directory of Open Access Journals (Sweden)

    Živković Predrag M.

    2004-01-01

    Full Text Available The possibility of the electro less deposition of chromium onto aluminum was investigated in order to improve non-printing element properties. It was determined that the electrochemical deposition of trivalent chromium was possible from alkaline solutions. The presence of chromium was confirmed by the EDAX procedure in three different laboratories. The influence of chromium on the wet ability of the nonprinting elements of the printing form was examined by drop spreading. Specimens were examined by pouring distilled water in drops onto the surface of the specimen. The picture of the drop was taken by a digital camera from two directions, in order to measure the diameter of the spreaded drop (a measuring gauge was recorded together with the drop and contact angle. The chromium-treated samples showed increased wettability compared with the non-chromium-treated samples. Improvement of the non-printing elements was confirmed during a printing test that was performed under real printing conditions. The purity of the prints made by two types of printing forms was analyzed in two ways: based on densitometric measurements and based on statistical analysis of the scanned print. Both methods of analysis of the control prints showed that the control prints made from chromium-treated specimens were purer than the prints made from the non-chromium-treated specimens. Considering that all the conditions of making the printing forms and the printing conditions, except the electro less deposition procedure were the same, it could be concluded that the electro less deposited layer of chromium improved the printing properties of the offset printing form because of the increased wettability.

  10. UV-visible and Raman investigations of matrix isolated adducts between metal vapors of chromium and benzene: selective photo-irradiations effects

    Science.gov (United States)

    Dalibart, M.; Derouault, J.

    1989-03-01

    The UV-visible absorption and the Raman spectra of chromium vapors trapped either in Ar-benzene mixtures or in neat benzene have been investigated. The data give evidence for the formation of the well-known dibenzene chromium sandwich complex but show also the formation of benzene complexes with the dimer Cr2 and with the cluster Cr3 photo-irradiations effects have been studied.

  11. On texture formation of chromium electrodeposits

    DEFF Research Database (Denmark)

    Nielsen, Christian Bergenstof; Leisner, Peter; Horsewell, Andy

    1998-01-01

    The microstructure, texture and hardness of electrodeposited hard, direct current (DC) chromium and pulsed reversed chromium has been investigated. These investigations suggest that the growth and texture of hard chromium is controlled by inhibition processes and reactions. Further, it has been...... established that codeposition of Cr2O3 nanoparticles is a general feature of DC chromium electrodeposition....

  12. EPR investigation of the trivalent chromium complexes in SrTiO.sub.3./sub..

    Czech Academy of Sciences Publication Activity Database

    Azamat, Dmitry; Dejneka, Alexandr; Lančok, Ján; Jastrabík, Lubomír; Trepakov, Vladimír; Bryknar, Z.; Neverova, E.V.; Badalyan, A. G.

    2014-01-01

    Roč. 75, č. 2 (2014), s. 271-275 ISSN 0022-3697 R&D Projects: GA MŠk(CZ) LM2011029; GA TA ČR TA01010517; GA ČR GAP108/12/1941 Grant - others:SAFMAT(XE) CZ.2.16/3.1.00/22132 Institutional support: RVO:68378271 Keywords : electron paramagnetic resonance (EPR) * SrTiO 3 * chromium complexes Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.853, year: 2014

  13. Investigation of IFMIF target assembly structure design

    International Nuclear Information System (INIS)

    Ida, Mizuho; Nakamura, Hiroo; Sugimoto, Masayoshi; Yamamura, Toshio

    2006-10-01

    In the International Fusion Materials Irradiation Facility (IFMIF), the back-wall of target assembly is the part suffered the highest neutron-flux. The back-wall and the assembly are designed to have lips for cutting/welding at the back-wall replacement. To reduce thermal stress and deformation of the back-wall under neutron irradiation, contact pressure between the back-wall and the assembly is one of dominant factors. Therefore, an investigation was performed for feasible clamping pressure of a mechanical clamp set in limited space around the back-wall. It was clarified that the clamp can give a pressure difference up to 0.4 MPa between the contact pressure and atmosphere pressure in the test cell room. Also a research was performed for the dissimilar metal welding in the back-wall. Use of 309 steel was found adequate as the intermediate filler metal through the research of previous welding. Maintaining a temperature of the target assembly so as to avoid a freezing of liquid lithium is needed at the lithium charge into the loop before the beam injection. The assembly is covered with thermal insulation. Therefore, a research and an investigation were performed for compact and light thermal-insulation effective even under helium (i.e. high heat-conduction) condition of the test cell room. The result was as follows; in the case that a thermal conductivity 0.008 W/m·K of one of found insulation materials is available in the temperature range up to 300degC of the IFMIF target assembly, needed thickness and weight of the insulation were respectively only 8.2 mm and 32 kg. Also a research was performed for high-heat-density heaters to maintain temperature of the back-wall which can not be cover with insulation due to limited space. A heater made of silicon-nitride was found to be adequate. Total heat of 8.4 kW on the back-wall was found to be achievable through an investigations of heater arrange. Also an investigation was performed for remote-handling device to

  14. Numerical Investigation of the IFMIF Lithium Target

    International Nuclear Information System (INIS)

    Gordeev, S.; Heinzel, V.; Slobodchuk, V.; Leichtle, D.; Anton Moeslang, A.

    2006-01-01

    The International Fusion Materials Facility (IFMIF) facility uses a high speed (10-20 m/s) Lithium (Li) jet flow as a target for two 40 MeV / 125 mA deuteron beams. The major function of the Li target is to provide a stable Li jet for the production of an intense neutron flux. For the understanding the lithium jet behaviour and elimination of the free-surface flow instabilities a detailed analysis of the Li jet flow is necessary. Numerical investigations of the IFMIF Li - Target have been performed with the CFD code Star-CD. A number of turbulence models were tested on the experimental data obtained at the water jet test facility of the Institute for Physics and Power Engineering (IPPE), Obninsk, Russia. Calculated and measured velocity profiles and thickness of the flow cross sections have been compared. The most suitable turbulence models were used for numerical investigations of the IFMIF Li-jet. For the analysis of the IFMIF Li target 3D models of the nozzle and jet flows have been developed. In the first part of analyses the nozzle flow effects, such as relaminarization of the accelerated flow, secondary motions and their influence on the development of the viscous layer and velocity profile have been investigated. Further evaluation of turbulence models was performed and recommendations for suitable turbulence models are given. Calculations predict the complete laminarization of the flow at the nozzle outlet for velocities less than 10 m/s. Within the transition region of velocities between 10 and 20 m/s calculations show the laminarization only in the first convergent part. In this case the acceleration dose not suppress secondary flows in the straight part near the nozzle exit. The second task is devoted to the stability of the Li jet flow. To this end, the influence of the nozzle outlet boundaries, jet curvature effects, gravity and surface tension on the free surface stability has been analysed. First calculations show, that such factors as gravity and

  15. An Investigation into the Accuracy of Two Currently Available Dental Impression Materials in the Construction of Cobalt-Chromium Frameworks for Removable Partial Dentures.

    Science.gov (United States)

    Dubal, Rajesh Kumar; Friel, Tim; Taylor, Philip D

    2015-03-01

    This study investigated the suitability of irreversible hydrocolloid as an impression material for cobalt-chromium framework construction. Scans of casts derived from (1) alginate and (2) addition-cured polyvinylsiloxane impressions were superposed on to a control. The differences within and between groups were compared at fixed landmarks. The investigation revealed a high degree of scan coincidence within and between groups. However, certain features, such as undercuts, resulted in a lower degree of scan coincidence. Irreversible hydrocolloid appears to be a viable alternative to addition-cured polyvinyl-siloxane as an impression material for cobalt-chromium framework construction.

  16. Investigation of Hexavalent Chromium Flux to Groundwater at the 100-C-7:1 Excavation Site

    Energy Technology Data Exchange (ETDEWEB)

    Truex, Michael J.; Vermeul, Vincent R.; Fritz, Brad G.; Mackley, Rob D.; Horner, Jacob A.; Johnson, Christian D.; Newcomer, Darrell R.

    2012-11-16

    Deep excavation of soil has been conducted at the 100-C-7 and 100-C-7:1 waste sites within the 100-BC Operable Unit at the Department of Energy (DOE) Hanford Site to remove hexavalent chromium (Cr(VI)) contamination with the excavations reaching to near the water table. Soil sampling showed that Cr(VI) contamination was still present at the bottom of the 100-C-7:1 excavation. In addition, Cr(VI) concentrations in a downgradient monitoring well have shown a transient spike of increased Cr(VI) concentration following initiation of excavation. Potentially, the increased Cr(VI) concentrations in the downgradient monitoring well are due to Cr(VI) from the excavation site. However, data were needed to evaluate this possibility and to quantify the overall impact of the 100-C-7:1 excavation site on groundwater. Data collected from a network of aquifer tubes installed across the floor of the 100-C-7:1 excavation and from temporary wells installed at the bottom of the entrance ramp to the excavation were used to evaluate Cr(VI) releases into the aquifer and to estimate local-scale hydraulic properties and groundwater flow velocity.

  17. Investigate of atmospheric arsenic, cadmium, chromium, lead, and mercury levels in moss species found around Zilkale, by EDXRF Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Akçay, Nilay, E-mail: nilay.akcay@erdogan.edu.tr [Recep Tayyip Erdoğan University, Faculty of Art and Science, Department of Physics, Rize (Turkey); Batan, Nevzat, E-mail: nbatan@ktu.edu.tr [Karadeniz Technical University, Maçka Vocational School, Trabzon (Turkey); Çinar, Yunus, E-mail: yunus.cinar@erdogan.edu.tr [Recep Tayyip Erdoğan University, Vocational School of Technical Studies, Rize (Turkey)

    2016-04-18

    Zilkale is a castle located in Fırtına Valley and it is one of the most important historical structures in Çamlihemşin district of Rize Province in the Black Sea Region of Turkey. The castle surrounded by very high mountains that poke up into the clouds, and it rains here all year round. Tourism businesses or industrial plants are not so much there yet. In recent years, Zilkale region has begun the attract tourist, people on treaking holidays in the Kaçkar. But many domestic and foreign tourists come to this region by own car or tour buses. The aim of this study is to investigate the atmospheric concentrations of arsenic, cadmium, chromium, lead, and mercury levels in five different moss species collected around Zilkale by using Energy Dispersive X-ray Fluorescence (EDXRF) Spectrometry. The average concentrations of heavy metals in moss samples ranged from 0.79-4.63 ppm for arsenic, 54.47-143.39 ppm for chromium, 39.97-81.03 ppm for lead. The values of cadmium and mercury were found below the detection limit. This study has shown that Hypnum cupressiforme, Abietinella abietina, Rhytidium rugosum, Plagiomnium undulate, and Thuidium tamariscinum samples collected around Zilkale were used to assess the potential contamination of atmospheric As, Cd, Cr, Pb, Hg contamination in the region and made important contributions toward the understanding of atmospheric As, Cd, Cr, Pb, Hg baseline data can be used for identification of changes in the levels of these heavy metals in the studied area.

  18. Investigation of thermal fatigue of chromium-molybdenum steels, used for calcining and agglomeration constructions

    International Nuclear Information System (INIS)

    Sinyavskij, D.P.; Gorkalo, A.P.

    1979-01-01

    The technique for investigating thermal fatigue of materials is described. The data on sample stress deformed state and current temperature values are taken from the local volume of the material studied. Results of investigating thermal fatigue of the 15KhMl and 20KhMl steels are presented

  19. Rapid Prototyping for In Vitro Knee Rig Investigations of Prosthetized Knee Biomechanics: Comparison with Cobalt-Chromium Alloy Implant Material

    Directory of Open Access Journals (Sweden)

    Christian Schröder

    2015-01-01

    Full Text Available Retropatellar complications after total knee arthroplasty (TKA such as anterior knee pain and subluxations might be related to altered patellofemoral biomechanics, in particular to trochlear design and femorotibial joint positioning. A method was developed to test femorotibial and patellofemoral joint modifications separately with 3D-rapid prototyped components for in vitro tests, but material differences may further influence results. This pilot study aims at validating the use of prostheses made of photopolymerized rapid prototype material (RPM by measuring the sliding friction with a ring-on-disc setup as well as knee kinematics and retropatellar pressure on a knee rig. Cobalt-chromium alloy (standard prosthesis material, SPM prostheses served as validation standard. Friction coefficients between these materials and polytetrafluoroethylene (PTFE were additionally tested as this latter material is commonly used to protect pressure sensors in experiments. No statistical differences were found between friction coefficients of both materials to PTFE. UHMWPE shows higher friction coefficient at low axial loads for RPM, a difference that disappears at higher load. No measurable statistical differences were found in knee kinematics and retropatellar pressure distribution. This suggests that using polymer prototypes may be a valid alternative to original components for in vitro TKA studies and future investigations on knee biomechanics.

  20. Rapid Prototyping for In Vitro Knee Rig Investigations of Prosthetized Knee Biomechanics: Comparison with Cobalt-Chromium Alloy Implant Material

    Science.gov (United States)

    Schröder, Christian; Steinbrück, Arnd; Müller, Tatjana; Woiczinski, Matthias; Chevalier, Yan; Müller, Peter E.; Jansson, Volkmar

    2015-01-01

    Retropatellar complications after total knee arthroplasty (TKA) such as anterior knee pain and subluxations might be related to altered patellofemoral biomechanics, in particular to trochlear design and femorotibial joint positioning. A method was developed to test femorotibial and patellofemoral joint modifications separately with 3D-rapid prototyped components for in vitro tests, but material differences may further influence results. This pilot study aims at validating the use of prostheses made of photopolymerized rapid prototype material (RPM) by measuring the sliding friction with a ring-on-disc setup as well as knee kinematics and retropatellar pressure on a knee rig. Cobalt-chromium alloy (standard prosthesis material, SPM) prostheses served as validation standard. Friction coefficients between these materials and polytetrafluoroethylene (PTFE) were additionally tested as this latter material is commonly used to protect pressure sensors in experiments. No statistical differences were found between friction coefficients of both materials to PTFE. UHMWPE shows higher friction coefficient at low axial loads for RPM, a difference that disappears at higher load. No measurable statistical differences were found in knee kinematics and retropatellar pressure distribution. This suggests that using polymer prototypes may be a valid alternative to original components for in vitro TKA studies and future investigations on knee biomechanics. PMID:25879019

  1. Spectroscopic investigations of matrix isolated adducts between metal vapors of chromium and benzene

    Science.gov (United States)

    Dalibart, M.; Derouault, J.; Labarrere, H.; Tranquille, M.

    1988-05-01

    UV-visible, infrared and Raman + fluorescence spectra of complexes of Cr with benzene have been investigated using cryogenic techniques. The formation of several different complexes is demonstrated and tentative identifications are proposed.

  2. Chromium doped TiO2 sputtered thin films synthesis, physical investigations and applications

    CERN Document Server

    Hajjaji, Anouar; Gaidi, Mounir; Bessais, Brahim; El Khakani, My Ali

    2014-01-01

    This book presents co-sputtered processes ways to produce chrome doped TiO2 thin films onto various substrates such as quartz, silicon and porous silicon. Emphasis is given on the link between the experimental preparation and physical characterization in terms of Cr content. Moreover, the structural, optical and optoelectronic investigations are emphasized throughout. The book explores the potencial applications of devices based on Cr doped TiO2 thin films as gas sensors and in photocatalysis and in the photovoltaic industry. Also, this book provides extensive leads into research literature, and each chapter contains details which aim to develop awareness of the subject and the methods used. The content presented here will be useful for graduate students as well as researchers in materials science, physics, chemistry and engineering.

  3. TEM investigations on the effect of chromium content and of stress relief treatment on precipitation in Alloy 82

    International Nuclear Information System (INIS)

    Sennour, M.; Chaumun, E.; Crépin, J.; Duhamel, C.; Gaslain, F.; Guerre, C.; Curières, I. de

    2013-01-01

    Highlights: •Slight change of the Cr content does not affect the microstructure of the butt welds. •Stress relief thermal treatment leads to the intergranular precipitation of Cr 23 C 6 . •The Cr 23 C 6 carbides are supposed to improve the SCC resistance of the butt welds. -- Abstract: Nickel-base alloys are widely used in nuclear Pressurized Water Reactors (PWRs). Most of them have been found susceptible to Stress Corrosion Cracking (SCC) in nominal PWR primary water. The time to initiation depends on the material and is longer for weld metals than for Alloy 600. This study will focus on Alloy 82, which is used in Dissimilar Metal Welds (DMWs). In service, DMWs are either in the as-welded state or have undergone a stress relief treatment. Previous SCC studies showed that the heat treatment reduces significantly the SCC susceptibility of the weld. In this context, this study focuses on the microstructure characterization of the weld in the as-welded state and in the heat-treated state. As chromium content is also a key factor for the SCC susceptibility, welds with low chromium content and medium chromium content were studied. The lower SCC susceptibility of the heat-treated welds was attributed to intergranular Cr 23 C 6 resulting from a combined effect of heat treatment and chromium and carbon contents. These intergranular carbides could explain the better behavior of Alloy 82, compared to other nickel-base alloys

  4. Investigating Festival's target cost function using perceptual experiments

    OpenAIRE

    Strom, Volker; King, Simon

    2008-01-01

    We describe an investigation of the target cost used in the Festival unit selection speech synthesis system. Our ultimate goal is to automatically learn a perceptually optimal target cost function. In this study, we investigated the behaviour of the target cost for one segment type. The target cost is based on counting the mismatches in several context features. A carrier sentence (``My name is Roger'') was synthesised using all 147,820 possible combinations of the diphones /n_ei/ and /ei_m/....

  5. Electrochemical investigation of chromium oxide-coated Ti-6Al-4V and Co-Cr-Mo alloy substrates.

    Science.gov (United States)

    Swaminathan, Viswanathan; Zeng, Haitong; Lawrynowicz, Daniel; Zhang, Zongtao; Gilbert, Jeremy L

    2011-08-01

    Hard coatings for articulating surfaces of total joint replacements may improve the overall wear resistance. However, any coating approach must take account of changes in corrosion behavior. This preliminary assessment analyzes the corrosion kinetics, impedance and mechanical-electrochemical stability of 100 μm thick plasma sprayed chromium oxide (Cr₂O₃) coatings on bearing surfaces in comparison to the native alloy oxide films on Co-Cr-Mo and Ti-6Al-6V. Cyclic potentiodynamic polarization, electrochemical impedance spectroscopy, and mechanical abrasion under potentiostatic conditions were performed on coated and substrate surfaces in physiological saline. SEM analysis characterized the coating morphology. The results showed that the corrosion current density values of chromium oxide coatings (0.4-1.2 μA/cm²) were of the same order of magnitude as Ti-6Al-4V alloy. Mechanical abrasion did not increase corrosion rates of chromium oxide coatings but did for uncoated Co-Cr-Mo and Ti-6Al-4V. The impedance response of chromium oxide coatings was very different than Co-Cr-Mo and Ti-6Al-4V native oxides characterized by a defected coating model. More of a frequency-independent purely resistive response was seen in mid-frequency range for the coatings (CPE(coat) : 40-280 nF/cm² (rad/s)(1-α) , α: 0.67-0.83) whereas a more capacitive character is seen for Co-Cr-Mo and Ti-6Al-4V (CPE(ox) around 20 μF/cm² (rad/s)(1-α) , α around 0.9). Pores, interparticle gaps and incomplete fusion typical for thermal spray coatings were present in these oxides which could have influenced corrosion resistance. The coating microstructure could have allowed some fluid penetration. Overall, these coatings appear to have suitable corrosion properties for wear surfaces. Copyright © 2011 Wiley Periodicals, Inc.

  6. Various X-ray diffraction investigations to study the oxidation mechanism of yttrium implanted chromium at elevate temperatures

    Science.gov (United States)

    Jacob, Y. P.; Buscail, H.; Caudron, E.; Cueff, R.; Stroosnijder, M. F.

    2002-07-01

    Attention is paid on the role played by yttrium implantation on the isothermal oxidation behaviour of pure chromium at high temperature. Chromium specimens were oxidized in synthetic air at 800, 900 and 1000 ^{circ}C. Many techniques such as Thermogravimetry, Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD) and in situ XRD were used to characterise the oxide scale formed on chromium-implanted specimens. We have shown that the presence of yttrium limits the nitrogen diffusion through the scale into the metallic matrix. Thus the formation of chromium nitrides is reduced and a better scale adherence is observed. Implanted yttrium has a beneficial effect on the chromium oxidation up to 900^{circ}C. We have shown, by in situ XRD, that it is related to the presence of the yttrium mixed oxide YCrO3 in the scale at high temperature. Cette étude porte sur l'oxydation du chrome pur dans l'air synthétique à 800, 900 et 1000 ^{circ}C. Plusieurs techniques, telles que l'analyse thermogravimétrique (ATG), la microscopie électronique à balayage (MEB) et la diffraction des rayons X (DRX) in situ, ont été employées pour caractériser les couches d'oxyde formées sur le chrome implanté à l'yttrium. Nous avons pu montrer que la présence de l'yttrium limite la diffusion de l'azote au travers de la couche d'oxyde et dans la matrice métallique sous-jacente. Ainsi, la formation des nitrures de chrome est plus faible et une meilleure adhérence de la couche d'oxyde est observée. L'yttrium implanté montre un effet bénéfique sur l'oxydation du chrome jusqu'à une temperature de 900^{circ}C. Nous avons pu montrer par diffraction des rayons X in situ que ce phénomène est lié à la présence de l'oxyde mixte YCrO3 dans la couche formée à haute température.

  7. Investigation of Creep Processes and Microdamages in 10Kh9V2MFBR-Sh High-Chromium Steel

    Science.gov (United States)

    Grin', E. A.; Pchelintsev, A. V.

    2018-01-01

    During the modernization and the new construction of power units at TPPs in Russia, high-chromium martensitic steels with higher heat-resistant properties than the traditional perlite steels are increasingly used as structural materials. High-chromium steels have a necessary regulatory support for their use in domestic power engineering. However, up to the present time, the issue of assessing the quality of these steels at the analysis of their state during long-term operation remains open. The article proposed is one of the first attempts to create a system of quality criteria for martensitic steels based on their microdamage parameters. Tests were carried out on the long-term strength and creep of samples from 10Kh9V2MFBR-Sh steel at high temperatures with the construction of creep curves in relative coordinates "deformation related to the deformation of fracture, current time related to time to failure." For some samples, the tests were interrupted and the metal was subjected to metallographic studies consisting of the analysis of microdamage with reference to the accumulated creep strain. It has been shown experimentally that the deformation curve of high-chromium steel differs from the analogous curve of pearlitic steel by a longer and flat section of steady creep and by a sharper transition to the third accelerated creep stage, which has a very short time period (approximately 10% of the total durability). The tendency to the increase in the microdamage of the structure of steel as the accumulated creep strain increases with time was confirmed. The beginning of transition to the final creep phase is characterized by the formation of contours of future pore chains and by the appearance of individual large pores of up to 6 μm in size, the presence of which in the microstructure of the martensitic steel indicates a very significant accumulation of creep strain, and corresponds to the predestruction stage of metal. It is necessary to continue the research to

  8. Remediation of soils contaminated with chromium using citric and hydrochloric acids: the role of chromium fractionation in chromium leaching.

    Science.gov (United States)

    Cheng, Shu-Fen; Huang, Chin-Yuan; Tu, Yao-Ting

    2011-01-01

    Acid washing is a common method for soil remediation, but is not always efficient for chromium-contaminated soil. Both soil particle size and the forms of chromium existing in the soil affect the efficiency of soil washing. Laboratory batch and column dissolution experiments were conducted to determine the efficiencies of citric and hydrochloric acids as agents to extract chromium from soils contaminated with chromium. The effects of soil particle size and chromium fractionation on Cr leaching were also investigated. About 90% of chromium in the studied soil existed either in residual form or bound to iron and manganese oxides, and Cr fraction distributions were similar for all soil particle sizes. Almost all exchangeable and carbonate-bound chromium was removed by washing once with 0.5 M HCl, whereas organic chromium was more effectively removed by washing with citric acid rather than with HCl solution of the same concentration. For chromium fractions that were either bound to Fe-Mn oxides or existed as residual forms, the efficiencies of acid washing were usually 20% or less, except for 0.5 M HCl solution, which had much higher efficiencies. Separation of the soil sample by particle size before the separate washing of the soil fractions had little improvement on the chromium removal.

  9. Final Work Plan: Targeted Investigation at York, Nebraska

    Energy Technology Data Exchange (ETDEWEB)

    LaFreniere, Lorraine M. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-08-01

    The targeted investigation at York will be implemented in phases, so that data collected and interpretations developed at each stage of the program can be evaluated to guide subsequent phases most effectively. Section 2 of this Work Plan presents a brief overview of the York site, its geologic and hydrologic setting, and the previous CCC/USDA investigations. Section 3, outlines the proposed technical program for the targeted investigation, and Section 4 describes the investigative methods to be employed. A community relations plan is in Section 5, and Section 6 includes health and safety information. In addition to this site-specific Work Plan, the Master Work Plan (Argonne 2002) developed by Argonne for CCC/USDA investigations in Nebraska should be consulted for complete details of the methods and procedures to be used at York.

  10. Stabilization of chromium salt in ordinary portland cement

    Indian Academy of Sciences (India)

    Ordinary Portland cement (OPC) samples containing the chromium salt have been investigated using differential microcalorimetry, conductometry and Fourier transform infrared spectroscopic analysis. The effect of chromium on OPC hydration was evaluated by continuous observing of early hydration.

  11. An investigation of force components in orthogonal cutting of medical grade cobalt-chromium alloy (ASTM F1537).

    Science.gov (United States)

    Baron, Szymon; Ahearne, Eamonn

    2017-04-01

    An ageing population, increased physical activity and obesity are identified as lifestyle changes that are contributing to the ongoing growth in the use of in-vivo prosthetics for total hip and knee arthroplasty. Cobalt-chromium-molybdenum (Co-Cr-Mo) alloys, due to their mechanical properties and excellent biocompatibility, qualify as a class of materials that meet the stringent functional requirements of these devices. To cost effectively assure the required dimensional and geometric tolerances, manufacturers rely on high-precision machining. However, a comprehensive literature review has shown that there has been limited research into the fundamental mechanisms in mechanical cutting of these alloys. This article reports on the determination of the basic cutting-force coefficients in orthogonal cutting of medical grade Co-Cr-Mo alloy ASTM F1537 over an extended range of cutting speeds ([Formula: see text]) and levels of undeformed chip thickness ([Formula: see text]). A detailed characterisation of the segmented chip morphology over this range is also reported, allowing for an estimation of the shear plane angle and, overall, providing a basis for macro-mechanic modelling of more complex cutting processes. The results are compared with a baseline medical grade titanium alloy, Ti-6Al-4V ASTM F136, and it is shown that the tangential and thrust-force components generated were, respectively, ≈35% and ≈84% higher, depending primarily on undeformed chip thickness but with some influence of the cutting speed.

  12. Chromium tolerance and reduction potential of Staphylococci ...

    African Journals Online (AJOL)

    In order to study the microbiology of chromium tolerance and reduction at a fly ash dumping site in South Africa, 15 core samples were investigated. It was shown that the 30 year old dumping site exhibited high concentrations of Cr (VI) ranging from 1.6 to 9.6 mg/g. From this contaminated fly ash dumping site, 67 chromium ...

  13. Environmental surveillance of commonly-grown vegetables for investigating potential lead and chromium contamination intensification in Bangladesh.

    Science.gov (United States)

    Hossain, A M M Maruf; Islam, M Shahidul; Mamun, M Mustafa; Al-Jonaed, H M; Imran, M; Rahman, M Hasibur; Kazi, M Azizul Islam; Elahi, Syed Fazle

    2016-01-01

    With regard to previously reported Lead (Pb) and Chromium (Cr) contamination in egg, a semi-quantitative assessment of the general environment of Bangladesh is carried out through nation-wide sampling of commonly grown and consumed vegetables. Five vegetables, namely, White Potato ( Solanum tuberosum ), Green Cabbage ( Brassica oleracea capitata var. alba L.), Red Spinach ( Amaranthus dubius ), White Radish ( Raphanus sativus var. longipinnatus ), and Green Bean ( Phaseolus vulgaris ) were selected for sampling from all 64 Districts of the country as per their availability during the sampling season. This results in a collection of 292 samples. Due to the necessity of incorporating a wide spectrum of vegetable types (e.g. tuber, brassica, leafy, root, and fruiting vegetables) as well as the need for including the geographic expanse of the whole country, replicates were not accommodated in the study, hence, the study being semi-quantitative in nature. The results do not substantiate evidence of public health risk due to Cr yet, with only 0.69 % of the samples found contaminated with Cr. Pb contamination (concentrations above a health-based guidance value) is found in 29.47 % of the samples; and together with the insight of such contamination likely being non-point origin, communicates on potential public health risk due to Pb as residual effects of extensive ambient atmospheric Pb pollution in recent history of the country. For the purpose of comparison, Cadmium (Cd) contents of the samples are also analyzed. Although there is no extensive Cd pollution history/source in the country, the likely point-source nature of Cd contamination found in 17.83 % of the samples indicates the scope of managing any existing contamination source by directing efforts into the potential point-sources.

  14. Final work plan for targeted investigation at Hilton, Kansas.

    Energy Technology Data Exchange (ETDEWEB)

    LaFreniere, L. M.; Environmental Science Division

    2007-08-28

    This Work Plan outlines the scope of a targeted investigation to update the status of carbon tetrachloride contamination in groundwater associated with grain storage operations at Hilton, Kansas. The Commodity Credit Corporation (CCC), an agency of the U.S. Department of Agriculture (USDA), operated a grain storage facility in Hilton during the 1950s and 1960s. At the time of the CCC/USDA operation in Hilton, grain storage facilities (CCC/USDA and private) were located along the both sides of the former Union Pacific railroad tracks (Figure 1.1). The main grain storage structures were on or near the railroad right-of-way. The proposed targeted investigation, to be conducted by Argonne National Laboratory on the behalf of CCC/USDA, will supplement Argonne's Phase I and Phase II investigations in 1996-1997. The earlier investigations erroneously focused on an area east of the railroad property where the CCC/USDA did not operate, specifically on a private grain storage facility. In addition, the investigation was limited in scope, because access to railroad property was denied (Argonne 1997a,b). The hydrogeologic system at Hilton is potentially complex.

  15. Investigation of the Mode of Action Underlying the Tumorigenic Response Induced in B6C3F1 Mice Exposed Orally to Hexavalent Chromium

    Science.gov (United States)

    Thompson, Chad M.; Proctor, Deborah M.; Haws, Laurie C.; Hébert, Charles D.; Grimes, Sheila D.; Shertzer, Howard G.; Kopec, Anna K.; Hixon, J.Gregory; Zacharewski, Timothy R.; Harris, Mark A.

    2011-01-01

    Chronic ingestion of high concentrations of hexavalent chromium [Cr(VI)] in drinking water induces intestinal tumors in mice. To investigate the mode of action (MOA) underlying these tumors, a 90-day drinking water study was conducted using similar exposure conditions as in a previous cancer bioassay, as well as lower (heretofore unexamined) drinking water concentrations. Tissue samples were collected in mice exposed for 7 or 90 days and subjected to histopathological, biochemical, toxicogenomic, and toxicokinetic analyses. Described herein are the results of toxicokinetic, biochemical, and pathological findings. Following 90 days of exposure to 0.3–520 mg/l of sodium dichromate dihydrate (SDD), total chromium concentrations in the duodenum were significantly elevated at ≥ 14 mg/l. At these concentrations, significant decreases in the reduced-to-oxidized glutathione ratio (GSH/GSSG) were observed. Beginning at 60 mg/l, intestinal lesions were observed including villous cytoplasmic vacuolization. Atrophy, apoptosis, and crypt hyperplasia were evident at ≥ 170 mg/l. Protein carbonyls were elevated at concentrations ≥ 4 mg/l SDD, whereas oxidative DNA damage, as assessed by 8-hydroxydeoxyguanosine, was not increased in any treatment group. Significant decreases in the GSH/GSSG ratio and similar histopathological lesions as observed in the duodenum were also observed in the jejunum following 90 days of exposure. Cytokine levels (e.g., interleukin-1β) were generally depressed or unaltered at the termination of the study. Overall, the data suggest that Cr(VI) in drinking water can induce oxidative stress, villous cytotoxicity, and crypt hyperplasia in the mouse intestine and may underlie the MOA of intestinal carcinogenesis in mice. PMID:21712504

  16. Chromium-induced skin damage among Taiwanese cement workers.

    Science.gov (United States)

    Chou, Tzu-Chieh; Wang, Po-Chih; Wu, Jyun-De; Sheu, Shiann-Cherng

    2016-10-01

    Little research has been done on the relationships between chromium exposure, skin barrier function, and other hygienic habits in cement workers. Our purpose was to investigate chromium-induced skin barrier disruption due to cement exposure among cement workers. One hundred and eight cement workers were recruited in this study. Urinary chromium concentration was used to characterize exposure levels. The biological exposure index was used to separate high and low chromium exposure. Transepidermal water loss (TEWL) was used to assess the skin barrier function. TEWL was significantly increased in workers with high chromium exposure levels than those with low chromium exposure levels (p = 0.048). A positive correlation was also found between urinary chromium concentration and TEWL (R = 0.28, p = 0.004). After adjusting for smoking status and glove use, a significant correlation between urinary chromium concentrations and TEWL remained. Moreover, workers who smoked and had a high chromium exposure had significantly increased TEWL compared to nonsmokers with low chromium exposure (p = 0.01). Skin barrier function of cement workers may have been disrupted by chromium in cement, and smoking might significantly enhance such skin barrier perturbation with chromium exposure. Decreased chromium skin exposure and smoking cessation should be encouraged at work. © The Author(s) 2015.

  17. Hexavalent Chromium Compounds

    Science.gov (United States)

    Learn about chromium, exposure to which can increase your risk of lung cancer and cancer of the paranasal sinuses and nasal cavity. Hexavalent chromium compounds have been used as corrosion inhibitors in a wide variety of products and processes.

  18. Experimental investigation of the IFMIF target mock-up

    International Nuclear Information System (INIS)

    Loginov, N.; Mikheyev, A.; Morozov, V.; Aksenov, Yu.; Arnol'dov, M.; Berensky, L.; Fedotovsky, V.; Chernov, V.; Nakamura, H.

    2009-01-01

    The international fusion materials irradiation facility (IFMIF) lithium neutron target mock-ups have been constructed and tested at water and lithium test facilities in the IPPE of Russia. Jet velocity in both mock-ups was up to 20 m/s. Calculations and experiments showed lithium flow instability at conjunction point of straight and concave sections of the mock-up back wall. Water velocity profile across the mock-up width, jet thickness, and wave height were measured. The significant increase of thickness of both water and lithium jets near the mock-up sidewalls was observed. The influence of shape of the nozzle outlet part on jet stability was investigated. Lithium evaporation from the jet free surface was investigated as well as lithium deposition on vacuum pipe walls of the target mock-up. It was shown that these phenomena are not very critical for the target efficiency. The possibility of lithium denitration down to 2 ppm (at 10 ppm requested) by means of aluminium getter was shown. Two types of cold traps and plug indicators of impurities were tested. The results are presented in the paper.

  19. Sorption of chromium(III) and chromium(VI) on lead sulfide

    International Nuclear Information System (INIS)

    Music, S.

    1985-01-01

    The sorption of chromium(III) and chromium(VI) on lead sulfide was investigated in dependence on pH, time of sorption, and on the concnetrations of sorbate and sorbent. The mechanisms of the sorption of Crsup(3+) and CrOsub(4)sup(2-) traces on lead sulfide are discussed; a difference between CrOsub(4)sup(2-) sorption on PbS and α-Fesub(2)Osub(3) was found. Sulfates and molybdates affect the removal of chromates from aqueous solutions. Lead sulfide carrier prepared in this work was also used for the preconcentration of chromium(III) and chromium(VI) from tap water. (author)

  20. Chromium allergy and dermatitis: prevalence and main findings

    DEFF Research Database (Denmark)

    Bregnbak, David; Johansen, Jeanne D.; Jellesen, Morten Stendahl

    2015-01-01

    The history of chromium as an allergen goes back more than a century, and includesan interventional success with national legislation that led to significant changes inthe epidemiology of chromium allergy in construction workers. The 2015 EU Leather Regulation once again put a focus on chromium...... allergy, emphasizing that the investigation of chromium allergy is still far from complete. Our review article on chromium focuses on the allergen’s chemical properties, its potential exposure sources, and the allergen’s interaction with the skin, and also provides an overview of the regulations...

  1. Hydraulic investigation on free surface flow of windowless target

    International Nuclear Information System (INIS)

    Hu Chen; Gu Hanyang

    2015-01-01

    The formation and control of free surface are the most essential parts in the studies of windowless target in ACCELERATOR-DRIVEN sub-critical system (ADS). Water model experiments and 360° full scale three dimensional simulations were conducted. The experimental study demonstrates that the free surface is significantly affected by the inlet flow velocity and outlet pressure. The length of free surface decreases in the second order with the increase of inlet flow velocity, while it decreases linearly with the outlet pressure. The structure and feature of flow field were investigated. The results show that the free surface is vulnerable to the vortex movement. Transient simulations were performed with volume of fluid (VOF) method, large eddy simulation (LES) and the pressure implicit with splitting of operators (PISO) algorithm. The simulation results agree qualitatively well with the experimental data related to both free surface flow and flow field. These simulation models and methods are proved to be applicable in the hydraulic simulations of liquid heavy metal target. (authors)

  2. Reproductive toxicological aspects of chromium in males

    International Nuclear Information System (INIS)

    Ernst, E.

    1994-01-01

    To expand our present understanding of the effects of chromium on male fertility a number of studies were designed to achieve this through the use of chromium intoxicated experimental animals and through investigation of sexual hormones and sperm quality in welders. Also in view of the lack of an experimental model for effects of noxious substance on the epididymal spermatozoa the main objectives of the series of studies reviewed here were: A. To establish a model for evaluation of epididymal sperm count and motility in the rat. B. To investigate and compare the effects of tri- and hexavalent chromium on epididymal spermatozoa. Further to describe the effects of low-dose long-time exposure of rats to the most toxicological interesting chromium oxidative state - hexavalent chromium. C. By the use of autoradiography and γ-countinuing to expand the present knowledge on the distribution of chromium in the body with special reference to the male reproductive organs. D. To describe the effects of exposure to hexavalent chromium in welding fume on levels of sexual hormones and semen parameters in welders. (EG)

  3. Reproductive toxicological aspects of chromium in males

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, E.

    1994-12-31

    To expand our present understanding of the effects of chromium on male fertility a number of studies were designed to achieve this through the use of chromium intoxicated experimental animals and through investigation of sexual hormones and sperm quality in welders. Also in view of the lack of an experimental model for effects of noxious substance on the epididymal spermatozoa the main objectives of the series of studies reviewed here were: A. To establish a model for evaluation of epididymal sperm count and motility in the rat. B. To investigate and compare the effects of tri- and hexavalent chromium on epididymal spermatozoa. Further to describe the effects of low-dose long-time exposure of rats to the most toxicological interesting chromium oxidative state - hexavalent chromium. C. By the use of autoradiography and {gamma}-countinuing to expand the present knowledge on the distribution of chromium in the body with special reference to the male reproductive organs. D. To describe the effects of exposure to hexavalent chromium in welding fume on levels of sexual hormones and semen parameters in welders. (EG).

  4. Nickel and chromium release from stents into isotonic NaCl solution investigated with the aid of neutron activation analysis

    International Nuclear Information System (INIS)

    Lin, X.; Portenlaenger, G.; Henkelmann, R.; Schulz, Ch.; Alt, E.

    1999-01-01

    Stent placement has become an effective treatment for abrupt or threatened vessel closure in recent years. As a preliminary investigation on the allergy problem towards to Ni and Cr metals from implanted stent, the release of the two elements from stents into isotonic NaCl solution was investigated. Trace amounts of Ni and Cr metals released from stents are successfully determined by neutron activation analysis (NAA). An extreme experimental condition is applied in the NAA procedure to reach a low detection limit of 1 ng Ni. A conclusion is given about the influence on the Ni and Cr release from gold coating, from the expansion, and from the different incubation periods. (author)

  5. Separation of valent forms of chromium (3) and chromium (6) by coprecipitation with iron (3) hydroxide

    International Nuclear Information System (INIS)

    Nazirmadov, B.; Khamidov, B.O.; Egorova, L.A.

    1988-01-01

    Soption 9.62x10 -5 mol/l of 51 Cr radioactive isotope in oxidation states 3 and 6 by iron(3) hydroxide in 1 mol/l of KNO 3 and KCl depending on pH medium is investigated. The region of practically total concentration of Cr(3) and Cr(6 + ) (pH=3-6.5) is determined. The results of spectrophotometric investigations, calculational data on distribution of hydroxocation forms of chromium (3) and of chromium (6) anions and sorption by iron (3) hydroxide permit to characterize sorption of chromium forms in different stages of oxidation. The methods of chromium (3) and chromium (6) separation by coprecipitation of iron (3) hydroxide and their precipitation from it is developed on the above foundation

  6. Experimental Investigation of the IFMIF Target Mock-up

    International Nuclear Information System (INIS)

    Loginov, N.; Mikheyev, A.; Morozov, V.; Aksenov, Y.; Arnoldov, M.; Berensky, L.; Fedotovsky, V.; Chernov, V.M.; Nakamura, H.

    2007-01-01

    Full text of publication follows: The IFMIF lithium neutron target mock-ups have been constructed and tested at the water and lithium test facilities. Description of the mock-ups and test facilities is presented in the paper, as well as the main results obtained. Reference geometry was used but the mockup flow cross-section was decreased. Velocity of water and lithium was up to reference value of 20 m/s. Features of lithium and water hydrodynamics were observed. The calculations and experiments showed that conjunction point of back wall straight and concave sections generated instability of lithium flow because of centrifugal force sudden change at this place. Therefore, it was proposed to use parabolic shape of the target back wall. Generation of wakes at the corners of cross-section of the Shima nozzle outlet was observed, and, as a result, surface waves appeared on the lithium jet. Observations of lithium and water jets and measurements of water jet thickness showed significant increasing the thickness near sidewalls of the mock-up concave section. It is because of absence of the centrifugal force at these places. Very large instability of the water jet surface was observed when outlet part of the Shima nozzle was divergent slightly (about 1 deg.), and vice versa very smooth jet surface occurred in confusing case (of about 0.5 deg.). So, nozzle outlet shape is very critical. Evaporation of lithium from the jet surface was investigated as well as deposition of vapor on vacuum pipe wall. It turned out to be not so critical. Significant part of the work concerned purification of lithium and monitoring impurities. The possibility of denitration of lithium down to 2 ppm by means of aluminum soluble getter was showed. Two types of both cold traps and plug indicators of impurities were tested. The results are presented in the paper. (authors)

  7. Final report : Phase III targeted investigation, Everest, Kansas.

    Energy Technology Data Exchange (ETDEWEB)

    LaFreniere, L. M.; Environmental Science Division

    2006-01-31

    The Commodity Credit Corporation (CCC), an agency of the U.S. Department of Agriculture (USDA), formerly operated grain storage facilities at two different locations at Everest, Kansas (Figure 1.1). One facility (referred to in this report as the Everest facility) was at the western edge of the city. The second facility (referred to in this report as Everest East) was about 0.5 mi northeast of the town. The CCC/USDA operated these facilities from the early 1950s until the early 1970s, at a time when commercial fumigants containing carbon tetrachloride were in common use by the CCC/USDA and private industry for the preservation of grain in storage. In 1997 the Kansas Department of Health and Environment (KDHE) sampled several domestic drinking water and non-drinking water wells in the Everest area as part of the CCC/USDA Private Well Sampling Program. All of the sampled wells were outside the Everest city limits. Carbon tetrachloride contamination was identified at a single domestic drinking water well (the Nigh well, DW06; Figure 1.1) approximately 3/8 mi northwest of the former Everest CCC/USDA grain storage facility. Subsequent KDHE investigations suggested that the contamination in DW06 could be linked to the former use of grain fumigants at the CCC/USDA facility. For this reason, the CCC/USDA is conducting a phased environmental study to determine the source and extent of the carbon tetrachloride contamination at Everest and to identify potential remedial options. The studies are being performed by the Environmental Research Division of Argonne National Laboratory. Two phases of investigation were completed previously; this report presents the findings of the targeted Phase III investigation at Everest.

  8. Exposure to chromium dust from homes in a Chromium Surveillance Project.

    Science.gov (United States)

    Freeman, N C; Stern, A H; Lioy, P J

    1997-01-01

    Investigators used a Lioy-Weisel-Wainman sampler to analyze the chromium content in house-dust samples obtained from households near chromium waste sites in Hudson County, New Jersey. Chromium concentrations in dust (microg/g)-indicative of non-background source contributions-were significantly higher in Jersey City homes than in control homes outside of Hudson County (228 and 111 microg/g, respectively; p amount of chromium available for contact and a direct measure of exposure potential, were also higher in Jersey City homes than in control homes (31 ng/cm2 and 14 ng/cm2, respectively; p = .008). Near some of the sites, investigators found elevated chromium dust loads more frequently in homes occupied by at least one household member who had elevated urine chromium, as determined in a separate screening project, than in homes occupied by members whose urine chromium was not elevated. Individuals with elevated urine chromium levels were found less frequently in homes in which good housekeeping practices were evident than in homes absent such practices.

  9. Diminishing Chromium Use on Combined Chromium-Gambier Tanning Process Upon the Characteristics of Tanned Leather

    Directory of Open Access Journals (Sweden)

    A. Kasim

    2014-04-01

    Full Text Available The research was aimed to investigate the influence of minimizing chromium use on combined chromium-gambier process upon the characteristics of tanned leather. At the first stage of tanning process, chromium was used and in the second stage it was replaced by gambier. The raw material used was dried saline-preserved goat skin. The treatments applied on the tanning process were the different concentrations of chromium ranging from the highest level of 6% to the lowest level of 1% which was then re-tanned by using 8% concentration of gambier. The examination parameters included chemical and physical properties as well as visual investigation on the tanned leather in accordance with SNI-06-0463-1989-A. The result showed that the tanning process by using 2% chromium in the first step and 8% gambier in the second step was a treatment combination producing tanned leather that met the standard. The examination on tanned leather resulted from such treatment showed 56.33% rawhide, 17.45% of bound tannin, 31.22% of tanning level, tensile strength 386.30 kg/cm2, flexibility 31.91%, leather width 1.3 mm, density 0.75 g/cm3, the leather was quite elastic with light brownish color. In conclusion, minimizing the use of chromium in the combined tanning process of chromium and gambier can be implemented to the lowest of 2% chromium concentration and 8% gambier in the first and second step, respectively.

  10. Chromium in diet

    Science.gov (United States)

    ... is important in the metabolism of fats and carbohydrates . It stimulates fatty acid and cholesterol synthesis, which are important for brain function and other body processes. Chromium also aids in insulin action and glucose metabolism. Food Sources The best source of chromium is brewer's yeast. ...

  11. Investigating different computed tomography techniques for internal target volume definition

    Directory of Open Access Journals (Sweden)

    S A Yoganathan

    2017-01-01

    Conclusions: When comparing with 4DCT, all the CT techniques underestimated ITV. In the absence of 4DCT, the HF-CBCT target volumes with appropriate margin may be a reasonable approach for defining the ITV.

  12. Electrochemistry of chromium(0)-aminocarbene complexes

    International Nuclear Information System (INIS)

    Hoskovcova, Irena; Rohacova, Jana; Meca, Ludek; Tobrman, Tomas; Dvorak, Dalimil; Ludvik, Jiri

    2005-01-01

    Two series of chromium(0)-(aryl)aminocarbene complexes substituted on the ligand phenyl ring were prepared and electrochemically investigated: pentacarbonyl((N,N-dimethylamino)(phenyl)carbene(chromium(0) (Ia-e) and chelated tetracarbonyl((η 2 -N-allyl-N-allylamino)(phenyl)carbene(chromium(0) (IIa, c-e). For comparison, a tungsten analogue of IIc (III) and a chromium chelate bearing a methyl substituent instead of the phenyl group IV were taken into the study. The intramolecular interactions of p-substituents on the ligand phenyl ring with the reduction and oxidation centres of the molecule of complex (followed electrochemically using LFER [P. Zuman, Substituent Effects in Organic Polarography, Plenum Press, New York, 1967]) enabled to localize the corresponding electron transfer. The influence of the type of coordination, the substituent on the ligand phenyl ring and the central metal atom on oxidation and reduction potentials is discussed

  13. Ex vivo investigation of magnetically targeted drug delivery system

    International Nuclear Information System (INIS)

    Yoshida, Y.; Fukui, S.; Fujimoto, S.; Mishima, F.; Takeda, S.; Izumi, Y.; Ohtani, S.; Fujitani, Y.; Nishijima, S.

    2007-01-01

    In conventional systemic drug delivery the drug is administered by intravenous injection; it then travels to the heart from where it is pumped to all regions of the body. When the drug is aimed at a small target region, this method is extremely inefficient and leads to require much larger doses than those being necessary. In order to overcome this problem a number of targeted drug delivery methods are developed. One of these, magnetically targeted drug delivery system (MT-DDS) will be a promising way, which involves binding a drug to small biocompatible magnetic particles, injecting these into the blood stream and using a high gradient magnetic field to pull them out of suspension in the target region. In the present paper, we describe an ex vivo experimental work. It is also reported that navigation and accumulation test of the magnetic particles in the Y-shaped glass tube was performed in order to examine the threshold of the magnetic force for accumulation. It is found that accumulation of the magnetic particles was succeeded in the blood vessel when a permanent magnet was placed at the vicinity of the blood vessel. This result indicates the feasibility of the magnetically drug targeting in the blood vessel

  14. Chromium supplementation improved post-stroke brain infarction and hyperglycemia.

    Science.gov (United States)

    Chen, Wen-Ying; Mao, Frank Chiahung; Liu, Chia-Hsin; Kuan, Yu-Hsiang; Lai, Nai-Wei; Wu, Chih-Cheng; Chen, Chun-Jung

    2016-04-01

    Hyperglycemia is common after acute stroke and is associated with a worse outcome of stroke. Thus, a better understanding of stress hyperglycemia is helpful to the prevention and therapeutic treatment of stroke. Chromium is an essential nutrient required for optimal insulin activity and normal carbohydrate and lipid metabolism. Beyond its nutritional effects, dietary supplement of chromium causes beneficial outcomes against several diseases, in particular diabetes-associated complications. In this study, we investigated whether post-stroke hyperglycemia involved chromium dynamic mobilization in a rat model of permanent focal cerebral ischemia and whether dietary supplement of chromium improved post-stroke injury and alterations. Stroke rats developed brain infarction, hyperglycemia, hyperinsulinemia, glucose intolerance, and insulin resistance. Post-stroke hyperglycemia was accompanied by elevated secretion of counter-regulatory hormones including glucagon, corticosterone, and norepinephrine, decreased insulin signaling in skeletal muscles, and increased hepatic gluconeogenesis. Correlation studies revealed that counter-regulatory hormone secretion showed a positive correlation with chromium loss and blood glucose increased together with chromium loss. Daily chromium supplementation increased tissue chromium levels, attenuated brain infarction, improved hyperglycemia, and decreased plasma levels of glucagon and corticosterone in stroke rats. Our findings suggest that stroke rats show disturbance of tissue chromium homeostasis with a net loss through urinary excretion and chromium mobilization and loss might be an alternative mechanism responsible for post-stroke hyperglycemia.

  15. Investigation of alternative phosphating treatments for nickel and hexavalent chromium elimination; Investigacao de tratamentos alternativos de fosfatizacao para eliminacao do niquel e cromo hexavalente

    Energy Technology Data Exchange (ETDEWEB)

    Jazbinsek, Luiz Antonio Rossi

    2014-07-01

    The phosphating processes are widely used in industry as surface treatments for metals, especially for low thickness plates, improving the adhesion between the metallic surface and the paint coating, and increasing the durability of paint systems against corrosion attacks. The tricationic phosphates containing zinc, nickel and manganese are commonly applied on steel. There is much discussion about the replacement of nickel by another element in order to have an environmentally friendly phosphating process. Niobium as a replacement for nickel has been evaluated. The most significant environmental impacts of phosphating processes are related to the presence of nickel and hexavalent chromium used in the process, this last as a passivation treatment. Nickel and hexavalent chromium are harmful to human and environment leading to contamination of water and soil. In the present study phosphate layers containing zinc, manganese and niobium have been evaluated and characterized on galvanized steel, and the results were compared with phosphates containing zinc, manganese and nickel, or a bicationic phosphate layer with zinc and manganese. Although the use of hexavalent chromium is not recommended worldwide, it is still used in processes for sealing the porosity of phosphate layers. This element is carcinogenic and has been associated with various diseases. Due to the passivation characteristics of niobium, this study also evaluated the tricationic bath containing niobium ammonium oxalate as a passivation treatment. The results showed that it could act as a replacement for the hexavalent chromium. The results of the present study showed that formulations containing niobium are potential replacements for hexavalent chromium and similar corrosion protection was obtained for the phosphate containing nickel or that with niobium. The morphology observed by scanning electron microscopy, gravimetric tests, porosity and adhesion evaluation results indicated that the phosphate

  16. Chromium carcinogenicity: California strategies.

    Science.gov (United States)

    Alexeeff, G V; Satin, K; Painter, P; Zeise, L; Popejoy, C; Murchison, G

    1989-10-01

    Hexavalent chromium was identified by California as a toxic air contaminant (TAC) in January 1986. The California Department of Health Services (CDHS) concurred with the findings of the International Agency for Research on Cancer that there is sufficient evidence to demonstrate the carcinogenicity of chromium in both animals and humans. CDHS did not find any compelling evidence demonstrating the existence of a threshold with respect to chromium carcinogenesis. Experimental data was judged inadequate to assess potential human reproductive risks from ambient exposures. Other health effects were not expected to occur at ambient levels. The theoretically increased lifetime carcinogenic risk from a continuous lifetime exposure to hexavalent chromium fell within the range 12-146 cancer cases per nanogram hexavalent chromium per cubic meter of air per million people exposed, depending on the potency estimate used. The primary sources found to contribute significantly to the risk of exposure were chrome platers, chromic acid anodizing facilities and cooling towers utilizing hexavalent chromium as a corrosion inhibitor. Evaluation of genotoxicity data, animal studies and epidemiological studies indicates that further consideration should be given to the potential carcinogenicity of hexavalent chromium via the oral route.

  17. Environmental exposure to arsenic and chromium in an industrial area

    OpenAIRE

    Vimercati, Luigi; Gatti, Maria F; Gagliardi, Tommaso; Cuccaro, Francesco; De Maria, Luigi; Caputi, Antonio; Quarato, Marco; Baldassarre, Antonio

    2017-01-01

    Arsenic and chromium are widespread environmental contaminants that affect global health due to their toxicity and carcinogenicity. To date, few studies have investigated exposure to arsenic and chromium in a population residing in a high-risk environmental area. The aim of this study is to evaluate the exposure to arsenic and chromium in the general population with no occupational exposure to these metals, resident in the industrial area of Taranto, Southern Italy, through biological monitor...

  18. Synthesis of chromium containing pigments from chromium galvanic sludges

    International Nuclear Information System (INIS)

    Andreola, F.; Barbieri, L.; Bondioli, F.; Cannio, M.; Ferrari, A.M.; Lancellotti, I.

    2008-01-01

    In this work the screening results of the scientific activity conducted on laboratory scale to valorise chromium(III) contained in the galvanic sludge as chromium precursor for ceramic pigments are reported. The valorisation of this waste as a secondary raw material (SRM) is obtained by achievement of thermal and chemical stable crystal structures able to color ceramic material. Two different pigments pink CaCr 0.04 Sn 0.97 SiO 5 and green Ca 3 Cr 2 (SiO 4 ) 3 were synthesized by solid-state reactions using dried Cr sludge as chromium oxide precursor. The obtained pigments were characterized by X-ray diffraction and SEM analysis. Furthermore the color developed in a suitable ceramic glaze was investigated in comparison with the color developed by the pigments prepared from pure Cr 2 O 3 . The characterization carried out corroborates the thermal and chemical stability of the synthesized pigments and, especially for the Cr-Sn pink pigment, the powders develop an intense color that is very similar to the color developed by the pigments obtained starting from pure Cr 2 O 3

  19. INVESTIGATION ON THE RESPONSE OF SEGMENTED CONCRETE TARGETS TO PROJECTILE IMPACTS

    Energy Technology Data Exchange (ETDEWEB)

    Booker, Paul M.; Cargile, James D.; Kistler, Bruce L.; La Saponara, Valeria

    2009-07-19

    The study of penetrator performance without free-surface effects can require prohibitively large monolithic targets. One alternative to monolithic targets is to use segmented targets made by stacking multiple concrete slabs in series. This paper presents an experimental investigation on the performance of segmented concrete targets. Six experiments were carried out on available small scale segmented and monolithic targets using instrumented projectiles. In all but one experiment using stacked slabs, the gap between slabs remained open. In the final experiment design, grout was inserted between the slabs, and this modification produced a target response that more closely represents that of the monolithic target. The results from this study suggest that further research on segmented targets is justified, to explore in more detail the response of segmented targets and the results of large scale tests when using segmented targets versus monolithic targets.

  20. Stabilization and solidification of chromium-contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Cherne, C.A.; Thomson, B.M. [Univ. of New Mexico, Albuquerque, NM (United States). Civil Engineering Dept.; Conway, R. [Sandia National Labs., Albuquerque, NM (United States)

    1997-11-01

    Chromium-contaminated soil is a common environmental problem in the United States as a result of numerous industrial processes involving chromium. Hexavalent chromium [Cr(VI)] is the species of most concern because of its toxicity and mobility in groundwater. One method of diminishing the environmental impact of chromium is to reduce it to a trivalent oxidation state [Cr(III)], in which it is relatively insoluble and nontoxic. This study investigated a stabilization and solidification process to minimize the chromium concentration in the Toxicity Characteristic Leaching Procedure (TCLP) extract and to produce a solidified waste form with a compressive strength in the range of 150 to 300 pounds per square inch (psi). To minimize the chromium in the TCLP extract, the chromium had to be reduced to the trivalent oxidation state. The average used in this study was an alluvium contaminated with chromic and sulfuric acid solutions. The chromium concentration in the in the in situ soil was 1212 milligrams per kilogram (mg/kg) total chromium and 275 mg/kg Cr(VI). The effectiveness of iron, ferrous sulfate to reduce Cr(VI) was tested in batch experiments.

  1. Chromium depletion from stainless steels during vacuum annealing

    International Nuclear Information System (INIS)

    Smith, A.F.; Hales, R.

    1977-01-01

    During selective chromium oxidation of stainless steels the changes in chromium concentration at the metal surface and in the metal have an important bearing on the overall oxidation performance. It has been proposed that an analogue of chromium behaviour during selective oxidation is obtained from volatilisation of chromium during high temperature vacuum annealing. In the present report the evaporation of chromium from 316 type of steel, vacuum annealed at 1,000 0 C, has been investigated by means of energy dispersive X-ray analysis and by neutron activation analysis. It was established that chromium loss from austenitic stainless steels is rate controlled by interdiffusion in the alloy. As predicted the chromium concentration at the metal surface decreased with increasing vacuum annealing time. The chromium depletion profile in the metal was in good agreement with the previously derived model apart from an anomalous region near the surface. Here the higher resolution of the neutron activation technique indicated a zone within approximately 2μm of the surface where the chromium concentration decreased more steeply than expected. (orig.) [de

  2. Removal of hexavalent chromium from aqueous solution using ...

    African Journals Online (AJOL)

    Removal of hexavalent chromium from aqueous solution using activated carbon derived from palmyra palm fruit seed. A. Kannan, S. Thambidurai. Abstract. In this study, removal of chromium(VI) from aqueous solutions by Palmyra palm fruit seed carbon (PPFSC) and commercial activated carbon (CAC) was investigated.

  3. Predicting chromium (VI) adsorption rate in the treatment of liquid ...

    African Journals Online (AJOL)

    The adsorption rate of chromium (VI) on commercial activated carbon during the treatment of the flocculation effluent of liquid-phase oil-based drill-cuttings has been investigated in terms of contact time and initial chromium (VI) ion concentration. Homogenizing 1 g of the activated carbon with 100 ml of the flocculation ...

  4. Biosorption of chromium by mangrove-derived Aplanochytrium sp ...

    African Journals Online (AJOL)

    The microbial dried biomass of Thraustochytrids is used as bioadsorbent for the removal of the chromium in aqueous solution. In this investigation, three species of Thraustochydrids namely Aplanochytrium sp., Thraustochytrium sp. and Schizochytrium sp. were tested for the efficiency of chromium accumulation by culturing ...

  5. 76 FR 8773 - Superalloy Degassed Chromium From Japan

    Science.gov (United States)

    2011-02-15

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-1090 (Review)] Superalloy Degassed Chromium From Japan AGENCY: United States International Trade Commission. ACTION: Termination of five-year... revocation of the antidumping duty order on superalloy degassed chromium from Japan would be likely to lead...

  6. The removal of chromium from wastewaters by activated bentonite

    International Nuclear Information System (INIS)

    Mellah, A.; Chegrouche, S.; Ait Ghezala, H.; Douar, L.

    1994-12-01

    The adsorption of chromium onto activated bentonite has been investigated. Adsorption isotherms were analysed to obtain the Langmuir and freundlich constants. The operating parameters (i.e pH, contact time, solid/liquid ratio, temperatureand initial chromium concentration) influenced the rate of adsorption have been studied

  7. Studies of ion implanted thermally oxidised chromium

    International Nuclear Information System (INIS)

    Muhl, S.

    1977-01-01

    The thermal oxidation of 99.99% pure chromium containing precise amounts of foreign elements has been studied and compared to the oxidation of pure chromium. Thirty-three foreign elements including all of the naturally occurring rare earth metals were ion implanted into chromium samples prior to oxidation at 750 0 C in oxygen. The role of radiation induced damage, inherent in this doping technique, has been studied by chromium implantations at various energies and doses. The repair of the damage has been studied by vacuum annealing at temperatures up to 800 0 C prior to oxidation. Many of the implants caused an inhibition of oxidation, the greatest being a 93% reduction for 2 x 10 16 ions/cm 2 of praseodymium. The distribution of the implant was investigated by the use of 2 MeV alpha backscattering and ion microprobe analysis. Differences in the topography and structure of the chromic oxide on and off the implanted area were studied using scanning electron and optical microscopy. X-ray diffraction analysis was used to investigate if a rare earth-chromium compound of a perovskite-type structure had been formed. Lastly, the electrical conductivity of chromic oxide on and off the implanted region was examined at low voltages. (author)

  8. 77 FR 32998 - Tin- and Chromium-Coated Steel Sheet From Japan

    Science.gov (United States)

    2012-06-04

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-860 (Second Review)] Tin- and Chromium... order on tin- and chromium-coated steel sheet from Japan would be likely to lead to continuation or... USITC Publication 4325 (May 2012), entitled Tin- and Chromium-Coated Steel Sheet from Japan...

  9. Determination of chromium in treated crayfish, Procambarus clarkii, by electrothermal ASS: study of chromium accumulation in different tissues

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, F.; Diaz, J.; Medina, J.; Del Ramo, J.; Pastor, A.

    1986-06-01

    In the present study, the authors investigated the accumulation of chromium in muscle, hepatopancreas, antennal glands, and gills of Procambarus clarkii (Girard) from Lake Albufera following Cr(VI)-exposure. Determinations of chromium were made by using Electrothermal Atomic Absorption Spectroscopy and the standard additions method.

  10. Investigation of americium-241 metal alloys for target applications

    International Nuclear Information System (INIS)

    Conner, W.V.; Rockwell International Corp., Golden, CO

    1982-01-01

    Several 241 Am metal alloys have been investigated for possible use in the Lawrence Livermore National Laboratory Radiochemical Diagnostic Tracer Program. Several properties were desired for an alloy to be useful for tracer program applications. A suitable alloy would have a fairly high density, be ductile, homogeneous and easy to prepare. Alloys investigated have included uranium-americium, aluminium-americium, and cerium-americium. Uranium-americium alloys with the desired properties proved to be difficult to prepare, and work with this alloy was discontinued. Aluminium-americium alloys were much easier to prepare, but the alloy consisted of an aluminium-americium intermetallic compound (AmAl 4 ) in an aluminum matrix. This alloy could be cast and formed into shapes, but the low density of aluminum, and other problems, made the alloy unsuitable for the intended application. Americium metal was found to have a high solid solubility in cerium and alloys prepared from these two elements exhibited all of the properties desired for the tracer program application. Cerium-americium alloys containing up to 34 wt% americium have been prepared using both co-melting and co-reduction techniques. The latter technique involves co-reduction of cerium tetrafluoride and americium tetrafluoride with calcium metal in a sealed reduction vessel. Casting techniques have been developed for preparing up to eight 2.2 cm (0.87 in) diameter disks in a single casting, and cerium-americium metal alloy disks containing from 10 to 25 wt% 241 Am have been prepared using these techniques. (orig.)

  11. Development of a coprecipitation system for the speciation/preconcentration of chromium in tap waters

    Energy Technology Data Exchange (ETDEWEB)

    Karatepe, Aslihan, E-mail: karatepea@gmail.com [Nevsehir University, Faculty of Science and Arts, Department of Chemistry, 50000 Nevsehir (Turkey); Korkmaz, Esra [Bozok University, Faculty of Science and Arts, Department of Chemistry, Yozgat (Turkey); Soylak, Mustafa [Erciyes University, Faculty of Science and Arts, Chemistry Department, 38039 Kayseri (Turkey); Elci, Latif [Pamukkale University, Faculty of Science and Arts, Department of Chemistry, 20020 Denizli (Turkey)

    2010-01-15

    A method for the speciation of chromium(III), chromium(VI) and determination of total chromium based on coprecipitation of chromium(III) with dysprosium hydroxide has been investigated and applied to tap water samples. Chromium(III) was quantitatively recovered by the presented method, while the recovery values for chromium(VI) was below 10%. The influences of analytical parameters including amount of dysprosium(III), pH, centrifugation speed and sample volume for the quantitative precipitation were examined. No interferic effects were observed from alkali, earth alkali and some transition metals for the analyte ions. The detection limits (k = 3, N = 15) were 0.65 {mu}g/L for chromium(III) and 0.78 {mu}g/L for chromium(VI). The validation of the presented method was checked by the analysis of certified reference materials.

  12. Development of a coprecipitation system for the speciation/preconcentration of chromium in tap waters

    International Nuclear Information System (INIS)

    Karatepe, Aslihan; Korkmaz, Esra; Soylak, Mustafa; Elci, Latif

    2010-01-01

    A method for the speciation of chromium(III), chromium(VI) and determination of total chromium based on coprecipitation of chromium(III) with dysprosium hydroxide has been investigated and applied to tap water samples. Chromium(III) was quantitatively recovered by the presented method, while the recovery values for chromium(VI) was below 10%. The influences of analytical parameters including amount of dysprosium(III), pH, centrifugation speed and sample volume for the quantitative precipitation were examined. No interferic effects were observed from alkali, earth alkali and some transition metals for the analyte ions. The detection limits (k = 3, N = 15) were 0.65 μg/L for chromium(III) and 0.78 μg/L for chromium(VI). The validation of the presented method was checked by the analysis of certified reference materials.

  13. The enriched chromium neutrino source for GALLEX

    International Nuclear Information System (INIS)

    Hartmann, F.X.; Hahn, R.L.

    1991-01-01

    The preparation and study of an intense source of neutrinos in the form of neutron irradiated materials which are enriched in Cr-50 for use in the GALLEX solar neutrino experiment are discussed. Chromyl fluoride gas is enriched in the Cr-50 isotope by gas centrifugation and subsequently converted to a very stable form of chromium oxide. The results of neutron activation analyses of such chromium samples indicate low levels of any long-lived activities, but show that short-lived activities, in particular Na-24, may be of concern. These results show that irradiating chromium oxide enriched in Cr-50 is preferable to irradiating either natural chromium or argon gas as a means of producing a neutrino source to calibrate the GALLEX detector. These results of the impurity level analysis of the enriched chromyl fluoride gas and its conversion to the oxide are also of interest to work in progress by other members of the Collaboration investigating an alternative conversion of the enriched gas to chromium metal. 35 refs., 12 figs., 5 tabs

  14. The effect of chronic chromium exposure on the health of Chinook salmon (Oncorhynchus tshawytscha)

    Science.gov (United States)

    Farag, A.M.; May, T.; Marty, G.D.; Easton, M.; Harper, D.D.; Little, E.E.; Cleveland, L.

    2006-01-01

    This study was designed to determine fish health impairment of Chinook salmon (Oncorhynchus tshawytscha) exposed to chromium. Juvenile Chinook salmon were exposed to aqueous chromium concentrations (0–266 μg l−1) that have been documented in porewater from bottom sediments and in well waters near salmon spawning areas in the Columbia River in the northwestern United States. After Chinook salmon parr were exposed to 24 and 54 μg Cr l−1 for 105 days, neither growth nor survival of parr was affected. On day 105, concentrations were increased from 24 to 120 μg Cr l−1and from 54 to 266 μg Cr l−1 until the end of the experiment on day 134. Weight of parr was decreased in the 24/120 μg Cr l−1 treatment, and survival was decreased in the 54/266 μg Cr l−1 treatment. Fish health was significantly impaired in both the 24/120 and 54/266 μg Cr l−1 treatments. The kidney is the target organ during chromium exposures through the water column. The kidneys of fish exposed to the greatest concentrations of chromium had gross and microscopic lesions (e.g. necrosis of cells lining kidney tububules) and products of lipid peroxidation were elevated. These changes were associated with elevated concentrations of chromium in the kidney, and reduced growth and survival. Also, variations in DNA in the blood were associated with pathological changes in the kidney and spleen. These changes suggest that chromium accumulates and enters the lipid peroxidation pathway where fatty acid damage and DNA damage (expressed as chromosome changes) occur to cause cell death and tissue damage. While most of the physiological malfunctions occurred following parr exposures to concentrations ≥120 μg Cr l−1, nuclear DNA damage followed exposures to 24 μg Cr l−1, which was the smallest concentration tested. The abnormalities measured during this study are particularly important because they are associated with impaired growth and reduced survival at

  15. Development of colloids for cell and tissue targeting: bisphosphonate-functionalized gold nanoparticles for the investigation of bone targeting

    OpenAIRE

    Zayed, Gamal

    2010-01-01

    Gold nanoparticles (GNPs) possess a great potential as model systems for the investigation of nanoparticulate drug delivery due to their ease of production, low toxicity and also the high stability of the noble metal in biological fluids. Due to their unique surface chemistry, they can be used as building platform for stable self assembled monolayers of thioalkylated poly(ethylene glycol)s with different surface functionalities, allowing the investigation of different drug targeting principle...

  16. Structure and magnetic properties of chromium doped cobalt molybdenum nitrides

    International Nuclear Information System (INIS)

    Guskos, Niko; Żołnierkiewicz, Grzegorz; Typek, Janusz; Guskos, Aleksander; Adamski, Paweł; Moszyński, Dariusz

    2016-01-01

    Four nanocomposites containing mixed phases of Co 3 Mo 3 N and Co 2 Mo 3 N doped with chromium have been prepared. A linear fit is found for relation between Co 2 Mo 3 N and chromium concentrations. The magnetization in ZFC and FC modes at different temperatures (2–300 K) and in applied magnetic fields (up to 70 kOe) have been investigated. It has been detected that many magnetic characteristics of the studied four nanocomposites correlate not with the chromium concentration but with nanocrystallite sizes. The obtained results were interpreted in terms of magnetic core-shell model of a nanoparticle involving paramagnetic core with two magnetic sublattices and a ferromagnetic shell related to chromium doping. - Highlights: • A new chromium doped mixed Co-Mn-N nanocomposites were synthesized. • Surface ferromagnetism was detected in a wide temperature range. • Core-shell model was applied to explain nanocomposites magnetism.

  17. Effects of UV light and chromium ions on wood flavonoids

    International Nuclear Information System (INIS)

    Molnárné Hamvas, L.; Németh, K.; Stipta, J.

    2003-01-01

    The individual and simultaneous effect of UV light and chromium ions was investigated by spectrophotometric methods on inert surfaces impregnated with quercetin or robinetin. The UV-VIS spectra of the silica gel plates impregnated with these flavonoids were modified characteristically after irradiating ultraviolet light. Even a half an hour of irradiation has caused irreversible changes in the molecule structure. A certain chemical - presumably complexation - was concluded from the change of spectral bands assigned to flavonoids when impregnated with chromic ions. Hexavalent chromium caused more complex changes in the absorption spectra. The differences in the spectra could indicate either the oxidation and decomposition of flavonoids, or some kind of coordination process and the reduction of hexavalent chromium. The simultaneous application of UV light and chromium ions caused more pronounced effects. The complexation process between chromium(III) and flavonoid was completed

  18. CHROMIUM BIOACCUMULATION FROM COMPOSTS AND VERMICOMPOSTS BASED ON TANNERY SLUDGES

    Directory of Open Access Journals (Sweden)

    Krzysztof GONDEK

    2008-07-01

    Full Text Available Storage of waste substances is not indifferent to ecological equilibrium in the environment therefore should not be the ultimate way to limit waste arduousness. Therefore, the conducted investigations aimed to determine the effect of tannery composts and vermicomposts loaded with chromium on this element bioaccumulation in earthworm bodies and biomass of selected plants. Chromium in composts and vermicomposts based on tannery sludges occurred in small quantities and easily soluble compounds. Chromium concentrations in redworm biomass points to this metal accumulation in Eisenia fetida body tissues. This element content in redworm biomass was signifi cantly positively correlated with its content in composts. Chromium content in plants was diversifi ed and on treatments was generally smaller than on mineral treatment or farmyard manure. Chromium absorbed by plants was stored mainly in the root systems, and over the norm content of this element found in vermicomposts did not cause its excessive accumulation in plant biomass.

  19. Chromium and aging

    Science.gov (United States)

    Aging is associated with increased blood glucose, insulin, blood lipids, and fat mass, and decreased lean body mass leading to increased incidences of diabetes and cardiovascular diseases. Improved chromium nutrition is associated with improvements in all of these variables. Insulin sensitivity de...

  20. Chromium isotope variations

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary

    Chromium (Cr) stable isotopes are a useful tracer of changes in redox conditions because changes in its oxidation state are accompanied by an isotopic fractionation. For this reason the Cr isotope system is being developed as a potential tool for paleo-redox reconstruction. Dissolved Cr in seawater...

  1. Thermodynamic Properties of Chromium Adsorption by Sediments ...

    African Journals Online (AJOL)

    The adsorption of Chromium from aqueous solution using river Watari sediment as an adsorbent was modeled. The influence of initial pH, solution temperature, adsorbent and adsorbate concentrations on the adsorption efficiency was investigated using batch equilibrium assays. From the results obtained for the adsorption ...

  2. seasonal variation in chromium hexavalent and copper ...

    African Journals Online (AJOL)

    Admin

    GLOBAL JOURNAL OF GEOLOGICAL SCIENCES VOL 8, NO. 2, 2010: 143- ... Seasonal variation in heavy metal contamination of groundwater in the Jimeta- Yola area was investigated. The objectives ... and anthropogenic input is the only source influencing the contamination indices in the case of chromium hexavalent.

  3. Increased chromium uptake in polymorphonuclear leukocytes from burned patients

    International Nuclear Information System (INIS)

    Davis, J.M.; Illner, H.; Dineen, P.

    1984-01-01

    Following thermal injury neutrophil function is severely impaired and thought to be hypometabolic; however, the host is considered to be hypermetabolic. To further investigate the metabolism and the function of neutrophils following thermal injury, neutrophil migration and chromium uptake were studied using radio-labelled neutrophils. Random and directed migration were found to be significantly reduced compared to control values. Neutrophil lysozyme content was also reduced in these burn cells while serum lysozyme from the same patients was significantly elevated over control values. These data suggest lysozyme is released by the neutrophil into the circulatory system. The influx of chromium in cells from burned patients was much greater than the influx in normal cells used in studies for chemotaxis. Influx of chromium over time and over varying concentrations of chromium was linear in cells from burned patients and normals. Cells from burned patients, however, took up more chromium than normals. Influx velocity of chromium was also determined and found to be greater in burn cells than normal cells. Since it has been shown that chromium influx is an energy-dependent reaction it is suggested that cellular energy stores are being depleted by the influx of chromium. Whether this is a response to an intracellular deficit or uncoupling of metabolic pathways is not known at this time

  4. Investigation of polarized-proton target materials by differential calorimetry: preliminary results

    International Nuclear Information System (INIS)

    Hill, D.A.; Hill, J.J.

    1980-01-01

    A simple differential calorimeter was designed and operated for an investigation of the thermodynamic properties of polarized target materials. The calibration and use of the calorimeter are discussed, after a brief exposition of our motivation for this work. The results of a preliminary study of target materials is presented with emphasis on the relevance of the glass state to dynamic polarization in chemically-doped targets

  5. Radiochemical Study on the Separation of Chromium-51 from the Irradiated Target by Using Commercial and/or Synthesized Ion Exchanger

    International Nuclear Information System (INIS)

    Aydia, M.I.M.M.

    2012-01-01

    This work involves the following steps:1- Preparation of Triton X-100 Cerium(IV) Phosphate (TX-100CeP) as a surface active ion exchanger or organometallic molecules. 2- Characterization of the TX-100CeP by different methods (i.e. IR, TGA/DTA X-ray diffraction, X-ray fluorescence and elemental analysis). 3- Development a method for separation and quantification of Cr(III) and Cr(VI) by using high pressure liquid chromatography (HPLC). 4- Separation of 51 Cr(III) from Cr(VI) in the target of K 2 CrO 4 on TX-100CeP and Permutit as a commercial ion exchanger. 5- Quality control on the separated 51 Cr(III).

  6. Investigation on powder metallurgy Cr-Si-Ta-Al alloy target for high-resistance thin film resistors with low temperature coefficient of resistance

    International Nuclear Information System (INIS)

    Wang, X.Y.; Zhang, Z.S.; Bai, T.

    2010-01-01

    The sputtering target for high-resistance thin film resistors plays a decisive role in temperature coefficient of resistance (TCR). Silicon-rich chromium (Cr)-silicon (Si) target was designed and smelted for high-resistance thin film resistors with low TCR. Valve metal tantalum (Ta) and aluminum (Al) were introduced to the Cr-Si target to improve the performance of the target prepared. The measures for grain refining in smelting Cr-Si-Ta-Al target were taken to improve the performance of the prepared target. The mechanism and role of grain refinement were discussed in the paper. The phase structure of the prepared target was detected by X-ray diffraction (XRD). Rate of temperature drop was studied to reduce the internal stress of alloy target and conquer the easy cracking disadvantage of silicon-rich target. The electrical properties of sputtered thin film resistors were tested to evaluate the performance of the prepared target indirectly.

  7. Separation of valence forms of chromium(III) and chromium(VI) by coprecipitation with iron(III) hydroxide

    International Nuclear Information System (INIS)

    Nazirmadov, B.; Khamidov, B.O.; Egorova, L.A.

    1989-01-01

    The sorption of 9.62·10 -5 M of Cr (III) and Cr (VI) with iron hydroxide in 1 M potassium nitrate and potassium chloride was investigated in relation to the pH of the medium. Experimental data on the sorption of chromium(III) and chromium(VI) with iron(III) hydroxide made it possible to determine the region of practically complete concentration of Cr (III) and Cr (VI) (pH = 3-6.5). The results from spectrophotometric investigations, calculated data on the distribution of the hydroxocationic forms of chromium(III) and the anions of chromium(IV), and their sorption by iron-(III) hydroxide made it possible to characterize the sorbability of the cationic and anionic forms of chromium in various degrees of oxidation. On this basis a method was developed for the separation of chromium(III) and chromium(VI) by coprecipitation on iron(III) hydroxide and their separation from the iron(III) hydroxide support

  8. Femtosecond laser surface structuring and oxidation of chromium thin coatings: Black chromium

    Energy Technology Data Exchange (ETDEWEB)

    Kotsedi, L., E-mail: Kotsedi@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Nuru, Z.Y. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Mthunzi, P. [National Laser Centre, Council for Scientific and Industrial Research, 0001 Pretoria (South Africa); Muller, T.F.G. [University of the Western Cape, Physics Department, Bellville, 7535 Cape Town (South Africa); Eaton, S.M. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Julies, B. [University of the Western Cape, Physics Department, Bellville, 7535 Cape Town (South Africa); Manikandan, E. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Ramponi, R. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa)

    2014-12-01

    Highlights: • Oxidation of the chromium thin film to chromium oxide by femtosecond laser with a fundamental wavelength of 1064 nm. • Solar absorber from chromium oxide that low percentage reflectance. • Femtosecond laser oxidation, with a de-focused laser. • Chromium oxide formation by femtosecond laser in normal ambient. - Abstract: In view of their potential applications as selective solar absorbers, chromium coatings on float glass substrates were nano/micro structured by femtosecond laser in air. Raman and X-rays diffraction investigations confirmed the formation of an ultra-porous α-Cr{sub 2}O{sub 3} layer at the surface; higher is the input laser power, enhanced is the crystallinity of the α-Cr{sub 2}O{sub 3} layer. The α-Cr{sub 2}O{sub 3} layer with the Cr underneath it in addition to the photo-induced porosity acted as a classical ceramic–metal nano-composite making the reflectance to decrease significantly within the spectral range of 190–1100 nm. The average reflectance decreased from 70 to 2%.

  9. Cavitation erosion of chromium-manganese and chromium-cobalt coatings processed by laser beam

    International Nuclear Information System (INIS)

    Giren, B.G.; Szkodo, M.

    2002-01-01

    In this work the cavitation erosion of chromium-manganese and chromium-cobalt clads were tested, each of them for three cases: (1) without additional processing; (2) after laser heating of the solid state and (3) after laser remelting of the material. Armco iron, carbon steel 45 and chromium-nickel steel 0H18N9T were used as substrates. C.W. CO 2 laser with a beam power of 1000 W was used as a source of radiation. The investigated samples were subjected to cavitation impingement in a rotating disk facility. The results indicate that laser processing of the thick, electrode deposited coatings by laser beam leads in some cases to an increase of their cavitation resistance. Strong dependence of the coatings performance on the substrate, both for the laser processed or unprocessed parts of the materials was also discovered. (author)

  10. Continuing investigations for technology assessment of 99Mo production from LEU [low enriched uranium] targets

    International Nuclear Information System (INIS)

    Vandegrift, G.F.; Kwok, J.D.; Marshall, S.L.; Vissers, D.R.; Matos, J.E.

    1987-01-01

    Currently much of the world's supply of 99m Tc for medical purposes is produced from 99 Mo derived from the fissioning of high enriched uranium (HEU). This paper presents the results of our continuing studies on the effects of substituting low enriched uranium (LEU) for HEU in targets for the production of fission product 99 Mo. Improvements in the electrodeposition of thin films of uranium metal continue to increase the appeal for the substitution of LEU metal for HEU oxide films in cylindrical targets. The process is effective for targets fabricated from stainless steel or zircaloy. Included is a cost estimate for setting up the necessary equipment to electrodeposit uranium metal on cylindrical targets. Further investigations on the effect of LEU substitution on processing of these targets are also reported. Substitution of uranium silicides for the uranium-aluminium alloy or uranium aluminide dispersed fuel used in current target designs will allow the substitution of LEU for HEU in these targets with equivalent 99 Mo-yield per target and no change in target geometries. However, this substitution will require modifications in current processing steps due to 1) the insolubility of uranium silicides in alkaline solutions and 2) the presence of significant quantities of silicate in solution. Results to date suggest that substitution of LEU for HEU can be achieved. (Author)

  11. 76 FR 58536 - Tin- and Chromium-Coated Steel Sheet From Japan; Notice of Commission Determination To Conduct a...

    Science.gov (United States)

    2011-09-21

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-860 (Second Review)] Tin- and Chromium... Concerning the Antidumping Duty Order on Tin- and Chromium-Coated Steel Sheet From Japan AGENCY: United.... 1675(c)(5)) to determine whether revocation of the antidumping duty order on tin- and chromium-coated...

  12. Femtosecond laser surface structuring and oxidation of chromium thin coatings: black chromium.

    CSIR Research Space (South Africa)

    Kotsedi, L

    2014-12-01

    Full Text Available In view of their potential applications as selective solar absorbers, chromium coatings on float glass substrates were nano/micro structured by femtosecond laser in air. Raman and X-rays diffraction investigations confirmed the formation of an ultra...

  13. Measuring Cytotoxicity by Bioluminescence Imaging Outperforms the Standard Chromium-51 Release Assay

    Science.gov (United States)

    Karimi, Mobin A.; Lee, Eric; Bachmann, Michael H.; Salicioni, Ana Maria; Behrens, Edward M.; Kambayashi, Taku; Baldwin, Cynthia L.

    2014-01-01

    The chromium-release assay developed in 1968 is still the most commonly used method to measure cytotoxicity by T cells and by natural killer cells. Target cells are loaded in vitro with radioactive chromium and lysis is determined by measuring chromium in the supernatant released by dying cells. Since then, alternative methods have been developed using different markers of target cell viability that do not involve radioactivity. Here, we compared and contrasted a bioluminescence (BLI)-based cytotoxicity assay to the standard radioactive chromium-release assay using an identical set of effector cells and tumor target cells. For this, we stably transduced several human and murine tumor cell lines to express luciferase. When co-cultured with cytotoxic effector cells, highly reproducible decreases in BLI were seen in an effector to target cell dose-dependent manner. When compared to results obtained from the chromium release assay, the performance of the BLI-based assay was superior, because of its robustness, increased signal-to-noise ratio, and faster kinetics. The reduced/delayed detection of cytotoxicity by the chromium release method was attributable to the association of chromium with structural components of the cell, which are released quickly by detergent solubilization but not by hypotonic lysis. We conclude that the (BLI)-based measurement of cytotoxicity offers a superior non-radioactive alternative to the chromium-release assay that is more robust and quicker to perform. PMID:24586714

  14. Chromium in Postmortem Material.

    Science.gov (United States)

    Dudek-Adamska, Danuta; Lech, Teresa; Konopka, Tomasz; Kościelniak, Paweł

    2018-04-17

    Recently, considerable attention has been paid to the negative effects caused by the presence and constant increase in concentration of heavy metals in the environment, as well as to the determination of their content in human biological samples. In this paper, the concentration of chromium in samples of blood and internal organs collected at autopsy from 21 female and 39 male non-occupationally exposed subjects is presented. Elemental analysis was carried out by an electrothermal atomic absorption spectrometer after microwave-assisted acid digestion. Reference ranges of chromium in the blood, brain, stomach, liver, kidneys, lungs, and heart (wet weight) in the population of Southern Poland were found to be 0.11-16.4 ng/mL, 4.7-136 ng/g, 6.1-76.4 ng/g, 11-506 ng/g, 2.9-298 ng/g, 13-798 ng/g, and 3.6-320 ng/g, respectively.

  15. Role of paramagnetic chromium in chromium(VI)-induced damage in cultured mammalian cells.

    OpenAIRE

    Sugiyama, M

    1994-01-01

    Chromium(VI) compounds are known to be potent toxic and carcinogenic agents. Because chromium(VI) is easily taken up by cells and is subsequently reduced to chromium(III), the formation of paramagnetic chromium such as chromium(V) and chromium(III) is believed to play a role in the adverse biological effects of chromium(VI) compounds. The present report, uses electron spin resonance (ESR) spectroscopy; the importance of the role of paramagnetic chromium in chromium(VI)-induced damage in intac...

  16. Specification for corrosion-resisting chromium and chromium-nickel steel covered welding electrodes

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    This specification prescribes requirements for covered corrosion-resisting chromium and chromium-nickel steel electrodes. These electrodes are normally used for shielded metal arc welding, and include those alloy steels designated as corrosion or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4.0% and nickel does not exceed 50.0%

  17. Specification for corrosion-resisting chromium and chromium-nickel steel covered welding electrodes

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    This specification prescribes requirements for covered corrosion-resisting chromium and chromium-nickel steel electrodes. These electrodes are normally used for shielded metal arc welding, and include those alloy steels designated as corrosion or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4.0 percent and nickel does not exceed 50.0 percent

  18. 29 CFR 1915.1026 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Chromium (VI). 1915.1026 Section 1915.1026 Labor... § 1915.1026 Chromium (VI). (a) Scope. (1) This standard applies to occupational exposures to chromium (VI... cement; or (4) Where the employer has objective data demonstrating that a material containing chromium or...

  19. 29 CFR 1926.1126 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Chromium (VI). 1926.1126 Section 1926.1126 Labor... Chromium (VI). (a) Scope. (1) This standard applies to occupational exposures to chromium (VI) in all forms... objective data demonstrating that a material containing chromium or a specific process, operation, or...

  20. 29 CFR 1910.1026 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 6 2010-07-01 2010-07-01 false Chromium (VI). 1910.1026 Section 1910.1026 Labor... Chromium (VI). (a) Scope. (1) This standard applies to occupational exposures to chromium (VI) in all forms... objective data demonstrating that a material containing chromium or a specific process, operation, or...

  1. Thermal hydraulic numerical investigation of the heavy liquid metal free surface of MYRRHA spallation target experimental

    International Nuclear Information System (INIS)

    Batta, A.; Class, A.

    2015-01-01

    The first advanced design of accelerator-driven systems (ADS) is currently being built in SCK-CEN (Mol, Belgium): MYRRHA (Multi-purpose hybrid research reactor for high-tech applications). The experiment investigates the free surface design of the MYRRHA target. The free surface lead-bismuth eutectic (LBE) liquid metal experiment is a full-scale model of the concentric MYRRHA target. The design of the target is combined with CFD simulations using a volume of fluid method accounting for mass transfer across the free surface. The model used has been validated with water experimental results. The design of the target enables a high fluid velocity and a stable surface at the beam entry. In the current work, we present numerical results of Star- CD simulations employing a high-resolution interface-capturing scheme in conjunction with the cavitation model for the nominal operation conditions. Thermal hydraulic of the target is considered for the nominal flow rate and nominal heat load. Results show that the target has a very stable free surface configuration for the considered flow rate and heat load

  2. Effect of compost and humic acid in mobility and concentration of cadmium and chromium in soil and plant

    Directory of Open Access Journals (Sweden)

    A. Chaab

    2016-12-01

    Full Text Available The effect of compost and humic acid in mobility and concentration of cadmium and chromium in contaminated soil were investigated. Experiment was carried out with three levels of soil cadmium and chromium and two organic matters (compost and humic acid. The study was performed in a randomized complete block design with 3 replicates. Results indicated that application of organic substances enhanced movement of cadmium and chromium in soil column. Humic acid is more effective than compost on the mobility of cadmium and chromium in soil. Mobility of cadmium and chromium in the lower depths of soil column were increased. Cadmium and chromium concentration in shoots and roots enhanced due to increasing those concentration in soil and application of organic substances. Increase in cadmium in shoots can be attributed to the high mobility of this element in maize plant. Maize root chromium concentration was greater than shoot chromium concentration. Humic acid was more effective than compost as cadmium and chromium concentration in root and shoot was concerned. Low mobility of chromium in plant and accumulation of chromium in roots can be reasons of decreasing of chromium concentration in shoot of plant and its bioaccumulation.

  3. Oral Chromium Exposure and Toxicity

    Science.gov (United States)

    Sun, Hong; Brocato, Jason

    2015-01-01

    Hexavalent chromium [Cr(VI)] is a known carcinogen when inhaled. However, inhalational exposure to Cr(VI) affects only a small portion of the population, mainly by occupational exposures. In contrast, oral exposure to Cr(VI) is widespread and affects many people throughout the globe. In 2008, the National Toxicology Program (NTP) released a 2-year study demonstrating that ingested Cr(VI) was carcinogenic in rats and mice. The effects of Cr(VI) oral exposure is mitigated by reduction in the gut, however a portion evades the reductive detoxification and reaches target tissues. Once Cr(VI) enters the cell, it ultimately gets reduced to Cr(III), which mediates its toxicity via induction of oxidative stress during the reduction while Cr intermediates react with protein and DNA. Cr(III) can form adducts with DNA that may lead to mutations. This review will discuss the potential adverse effects of oral exposure to Cr(VI) by presenting up-to-date human and animal studies, examining the underlying mechanisms that mediate Cr(VI) toxicity, as well as highlighting opportunities for future research. PMID:26231506

  4. Oral Chromium Exposure and Toxicity.

    Science.gov (United States)

    Sun, Hong; Brocato, Jason; Costa, Max

    2015-09-01

    Hexavalent chromium [Cr(VI)] is a known carcinogen when inhaled. However, inhalational exposure to Cr(VI) affects only a small portion of the population, mainly by occupational exposures. In contrast, oral exposure to Cr(VI) is widespread and affects many people throughout the globe. In 2008, the National Toxicology Program (NTP) released a 2-year study demonstrating that ingested Cr(VI) was carcinogenic in rats and mice. The effects of Cr(VI) oral exposure are mitigated by reduction in the gut; however, a portion evades the reductive detoxification and reaches target tissues. Once Cr(VI) enters the cell, it ultimately gets reduced to Cr(III), which mediates its toxicity via induction of oxidative stress during the reduction while Cr intermediates react with protein and DNA. Cr(III) can form adducts with DNA that may lead to mutations. This review will discuss the potential adverse effects of oral exposure to Cr(VI) by presenting up-to-date human and animal studies, examining the underlying mechanisms that mediate Cr(VI) toxicity, as well as highlighting opportunities for future research.

  5. Thermal-hydraulics investigations for the Liquid Lead-Bismuth Target of the SINQ spallation source

    International Nuclear Information System (INIS)

    Sigg, B.; Dury, T.; Hudina, M.; Smith, B.

    1991-01-01

    The paper contains a discussion of the thermal-hydraulic problems of the target which require detailed analysis by means of a two- or three-dimensional space- and in part also time-dependent fluid dynamics code. There follows a short description of the general-purpose code ASTEC, which is being used for these investigations, and examples of the target modelling, including results. The final part of the paper is devoted to a short discussion of experiments against which this application of the code has to be validated. (author)

  6. Nanoscale investigation of the degradation mechanism of a historical chrome yellow paint by quantitative electron energy loss spectroscopy mapping of chromium species.

    Science.gov (United States)

    Tan, Haiyan; Tian, He; Verbeeck, Jo; Monico, Letizia; Janssens, Koen; Van Tendeloo, Gustaaf

    2013-10-18

    Getting the picture: The investigation of 100 year old chrome yellow paint by transmission electron microscopy and spectroscopy has led to the identification of four types of core-shell particles. This nanoscale investigation has allowed a mechanism to be proposed for the darkening of some bright yellow colors in Van Gogh's paintings (e.g. in Falling leaves (Les Alyscamps), 1888). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Preparation of Silica Modified with 2-Mercaptoimidazole and its SorptionProperties of Chromium(III

    Directory of Open Access Journals (Sweden)

    Harry Budiman

    2009-01-01

    Full Text Available Modified silica gel was prepared to remove the heavy metal of chromium(III from water sample. Silica gel was used as supporting material and the 2-mercaptoimidazole was immobilized onto surface silica so that the silica would have selective properties to adsorb the heavy metal chromium(III through the formation of coordination compound between the 2-mercaptoimidazole and chromium(III. The characterization of modified silica gel was carried out by analyzing the Fourier Transform Infrared Spectrum of this material in order to ensure the immobilization of 2-mercaptoimidazole onto the surface. The effect of pH solution, initial concentration of chromium(III, and interaction time were investigated in batch mode to find the adsorption properties of chromium(III onto modified silica. The condition optimum of these parameters was applied to determine the removal percentage of chromium(III in water sample using the modified silica gel

  8. The prevalence of chromium allergy in Denmark is currently increasing as a result of leather exposure

    DEFF Research Database (Denmark)

    Thyssen, J P; Jensen, P; Carlsen, B C

    2009-01-01

    BACKGROUND: Chromium allergy has traditionally been caused by occupational skin contact with cement. In 1983, Danish legislation made the addition of ferrous sulphate compulsory in cement to reduce the water-soluble chromium content to not more than 2 ppm. An effect from this intervention has...... previously been demonstrated among Danish construction workers. OBJECTIVES: To investigate the development of chromium allergy among patients with dermatitis tested between 1985 and 2007 in Denmark. Furthermore, to determine causative exposures in patients with chromium allergy. PATIENTS AND METHODS......: A retrospective analysis of patch test data was performed (n = 16,228) and charts from patients with chromium allergy were reviewed. Comparisons were made using a chi(2) test. Logistic regression analyses were used to test for associations. RESULTS: The prevalence of chromium allergy decreased significantly from...

  9. A highly selective chemiluminescent probe for the detection of chromium(VI)

    Science.gov (United States)

    Jin, Yan; Sun, Yonghua; Li, Chongying; Yang, Chao

    2018-03-01

    In present work, rhodamine B hydrazide and rhodamine 6G hydrazide were synthesized and the chemiluminescence performance has been investigated. Based on the chemiluminescence of rhodamine 6G hydrazide‑chromium(VI), a selective and sensitive method for the direct detection of chromium(VI) was developed. The chemiluminescence intensity was linearly related to the concentration of chromium(VI) in the range of 2.60 × 10- 8-8.00 × 10- 6 mol/L with a correlation coefficient of r = 0.998 and a detection limit of 1.4 × 10- 8 mol/L (S/N = 3). The results indicated rhodamine 6G hydrazide was an excellent chemiluminescent probe for chromium(VI) without reduction of chromium(VI) to chromium(III). A possible mechanism of CL emission was also suggested.

  10. Influence of the laser pre-quenched substrate on an electroplated chromium coating/steel substrate

    Science.gov (United States)

    Chen, Xuejun; Yan, Qian; Ma, Qian

    2017-05-01

    The chromium coatings were electroplated onto a laser pre-quenched steel substrate to improve the interfacial adhesion properties of chromium coating/steel substrate system. The influence of laser pre-treatment on the substrate, coating as well as interface was investigated by using microstructure characterization, hardness testing, tensile testing and finite element analysis. An apparent boundary line instead of an interlayer was identified between chromium coating/pre-quenched steel substrate. The Vickers hardness and yield strength of steel substrate were significantly improved after laser pre-quenching. The fracture toughness of chromium coating was increased by about 28.6% compared to the un-treated counterpart. The energy release rate for an interfacial crack in the chromium coating/laser-quenched substrate was smaller than that in the untreated specimen. These results may help understand the life prolongation mechanism for the laser pre-quenched chromium/coated steel parts.

  11. Chemical investigations of isotope separation on line target units for carbon and nitrogen beams

    CERN Document Server

    Franberg, H; Gäggeler, H W; Köster, U

    2006-01-01

    Radioactive ion beams (RIBs) are of significant interest in a number of applications. Isotope separation on line (ISOL) facilities provide RIB with high beam intensities and good beam quality. An atom that is produced within the ISOL target will first diffuse out from the target material. During the effusion towards the transfer line and into the ion source the many contacts with the surrounding surfaces may cause unacceptable delays in the transport and, hence, losses of the shorter-lived isotopes. We performed systematic chemical investigations of adsorption in a temperature and concentration regime relevant for ISOL targets and ion source units, with regard to CO/sub x/ and NOmaterials are potential construction materials for the above-mentioned areas. Off-line and on-line tests have been performed using a gas thermochromatography setup with radioactive tracers. The experiments were performed at the production of tracers for atmospheric chemistry (PROTRAC) facility at the Paul Schener Institute in Villigen...

  12. Influence of IR-laser irradiation on α-SiC-chromium silicides ceramics

    International Nuclear Information System (INIS)

    Vlasova, M.; Marquez Aguilar, P.A.; Resendiz-Gonzalez, M.C.; Kakazey, M.; Bykov, A.; Gonzalez Morales, I.

    2005-01-01

    This project investigated the influence of IR-laser irradiation (λ = 1064 nm, P = 240 mW) on composite ceramics SiC-chromium silicides (CrSi 2 , CrSi, Cr 5 Si 3 ) by methods of X-ray diffraction, electron microscopy, atomic force microscopy, and X-ray microanalysis. Samples were irradiated in air. It was established that a surface temperature of 1990 K was required to melt chromium silicides, evaporate silicon from SiC, oxidize chromium silicides, and enrich superficial layer by carbon and chromium oxide

  13. An investigative approach to explore optimum assembly process design for annular targets carrying LEU foil

    Science.gov (United States)

    Hoyer, Annemarie

    Technetium-99m is the most widely used nuclear isotope in the medical field, with nearly 80 to 85% of all diagnostic imaging procedures. The daughter isotope of molybdenum-99 is currently produced using weapons-grade uranium. A suggested design for aluminum targets carrying low-enriched uranium (LEU) foil is presented for the fulfillment of eliminating highly enriched uranium (HEU) for medical isotope production. The assembly process that this research focuses on is the conventional draw-plug process which is currently used and lastly the sealing process. The research is unique in that it is a systematic approach to explore the optimal target assembly process to produce those targets with the required quality and integrity. Conducting 9 parametric experiments, aluminum tubes with a nickel foil fission-barrier and a surrogate stainless steel foil are assembled, welded and then examined to find defects, to determine residual stresses, and to find the best cost-effective target dimensions. The experimental design consists of 9 assembly combinations that were found through orthogonal arrays in order to explore the significance of each factor. Using probabilistic modeling, the parametric study is investigated using the Taguchi method of robust analysis. Depending on the situation, optimal conditions may be a nominal, a minimized or occasionally a maximized condition. The results will provide the best target design and will give optimal quality with little or no assembly defects.

  14. Final report : results of the 2007 targeted investigation at Hilton, Kansas.

    Energy Technology Data Exchange (ETDEWEB)

    LaFreniere, L. M.; Environmental Science Division

    2008-04-29

    The Commodity Credit Corporation (CCC), an agency of the U.S. Department of Agriculture (USDA), operated a grain storage facility in Hilton, Kansas, in 1954-1965. In 1992, carbon tetrachloride was first identified, at a concentration of 910 {micro}g/L, in groundwater from well GW01 at Hilton. This discovery occurred in association with the sale of the private grain storage facility on which well GW01 is located to the current owner, the Mid-Kansas Cooperative Association. The Kansas Department of Health and Environment conducted investigations at Hilton in 1992-1994. In 1996-1997, Argonne National Laboratory conducted Phase I and Phase II investigations on behalf of the CCC/USDA to characterize the distribution of the carbon tetrachloride contamination identified in well GW01, the stratigraphic units potentially hosting contaminant migration, and local hydrogeology in the Hilton area. The 2007 targeted investigation reported here focused specifically on the former CCC/USDA property at Hilton, west of the railroad tracks. (Until a property record search in 2005, the location of the CCC/USDA's former facility at Hilton was not known with certainty.) The objectives of the investigation, as implemented, were to (1) investigate for carbon tetrachloride contamination in the shallower soil and shallow aquifer units below the former CCC/USDA property and (2) investigate groundwater flow patterns. The key results of the 2007 targeted investigation are as follows: (1) No carbon tetrachloride or chloroform contamination was found in soil or groundwater below the former CCC/USDA facility. (2) The 2007 groundwater level data support a southwesterly direction for groundwater flow in the main Hilton aquifer (Equus Beds), consistent with findings of previous investigations. Contaminated well GW01 was confirmed to be upgradient from the former CCC/USDA facility. (3) The contaminants carbon tetrachloride, chloroform, and 1,2-dibromoethane (ethylene dibromide) were found in

  15. Effects of vacuum processing erbium dideuteride/ditritide films deposited on chromium underlays on copper substrates

    International Nuclear Information System (INIS)

    Provo, J.L.

    1978-01-01

    Thin films of erbium dideuteride/ditritide were experimentally produced on chromium underlays deposited on copper substrates. The chromium underlay is required to prevent erbium occluder/copper substrate alloying which inhibits hydriding. Data taken has shown that vacuum processing affects the erbium/chromium/copper interaction. With an in situ process in which underlay/occluder films are vacuum deposited onto copper substrates and hydrided with no air exposure between these steps, data indicates a minimum of 1500A of chromium is required for optimum hydriding. If films are vacuum deposited as above and air-exposed before hydriding, a minimum of 3000A of chromium was shown to be required for equivalent hydriding. Data suggests that the activation step (600 0 C for 1 hour) required for hydriding the film of the second type is responsible for the difference observed. Such underlay thickness parameters are important, with regard to heat transfer considerations in thin hydride targets used for neutron generation

  16. Genotoxic Effects Due to Exposure to Chromium and Nickel Among Electroplating Workers.

    Science.gov (United States)

    El Safty, Amal Mohamed Kamal; Samir, Aisha Mohamed; Mekkawy, Mona Kamal; Fouad, Marwa Mohamed

    2018-01-01

    Using chromium and nickel for electroplating is important in many industries. This process induces variable adverse health effects among exposed workers. The aim of this study is to detect the genotoxic effects of combined exposure to chromium and nickel among electroplating workers. This study was conducted on 41 male workers occupationally exposed to chromium and nickel in the electroplating section of a factory compared to 41 male nonexposed individuals, where full history and clinical examination were performed. Laboratory investigations included measurement of serum chromium, nickel, 8-hydroxydeoxyguanosine (8-OHdG), and micronuclei were measured in buccal cells. In exposed workers, serum chromium ranged from 0.09 to 7.20 µg/L, serum nickel ranged from 1.20 to 28.00 µg/L, serum 8-OHdG ranged from 1.09 to12.60 ng/mL, and these results were statistically significantly increased compared to nonexposed group ( P exposure to chromium and nickel increases serum 8-OHdG by 4.754 (95% confidence interval [CI]: 3.54-5.96). The model found that exposure to chromium and nickel increases micronucleus by 35.927 (95% CI: 28.517-43.337). Serum 8-OHdG and micronucleus test in buccal cells were increased with combined exposure to chromium and nickel. The current research concluded that workers exposed to nickel and chromium in electroplating industry are at risk of significant cytogenetic damage.

  17. Toxicokinetics of hexavalent chromium in the rat after intratracheal administration of chromates of different solubilities

    NARCIS (Netherlands)

    Bragt, P.C.; Dura, E.A. van

    1983-01-01

    The kinetics of chromium in the rat after a single intratracheal dose of sodium, zinc or lead 51Cr-chromate have been investigated. Sodium chromate and the less soluble zinc chromate were absorbed into the blood and this resulted in increased excretion of chromium into the urine. The insoluble lead

  18. The temperature gradient on section of casting in process of primary crystallization of chromium cast iron

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2008-08-01

    Full Text Available The methodology of defining in article was introduced the temperature gradient in process of primary crystallization during cooling the casting from chromium cast iron on basis of measurements of thermal field in test DTA-K3. Insert also the preliminary results of investigations of influence temperature gradient on structure of studied wear resistance chromium cast iron.

  19. Teaching the Properties of Chromium's Oxidation States with a Case Study Method

    Science.gov (United States)

    Ozdilek, Zehra

    2015-01-01

    The purpose of this study was to investigate how a mixed-method case study affects pre-service science teachers' awareness of hexavalent chromium pollution and content knowledge about the properties of chromium's different oxidation states. The study was conducted in Turkey with 55 sophomores during the fall semester of 2013-2014. The students…

  20. Experimental and numerical investigation of liquid-metal free-surface flows in spallation targets

    Energy Technology Data Exchange (ETDEWEB)

    Batta, A., E-mail: batta@kit.edu [Karlsruhe Institute of Technology, Germany Hermann-von-Helmholtz-PLATZ 1, 76344 Eggenstein-Leopoldshafen (Germany); Class, A.G.; Litfin, K.; Wetzel, Th. [Karlsruhe Institute of Technology, Germany Hermann-von-Helmholtz-PLATZ 1, 76344 Eggenstein-Leopoldshafen (Germany); Moreau, V.; Massidda, L. [CRS4 Centre for Advanced Studies, Research and Development in Sardinia, Polaris, Edificio 1, 09010 Pula, CA (Italy); Thomas, S.; Lakehal, D. [ASCOMP GmbH Zurich, Zurich (Switzerland); Angeli, D.; Losi, G. [DIEF – Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, via Vignolese 905, 41125 Modena (Italy); Mooney, K.G. [University of Massachusetts Amherst, Department of Mechanical and Industrial Engineering, Amherst (United States); Van Tichelen, K. [SCK-CEN, Belgian Nuclear Research Centre, Boeretang 200, 2400 Mol (Belgium)

    2015-08-15

    Highlights: • Experimental study of free surface for lead bismuth eutectic target. • Numerical investigation of free surface of a liquid metal target. • Advanced free surface modelling. - Abstract: Accelerator Driven Systems (ADS) are extensively investigated for the transmutation of high-level nuclear waste within many worldwide research programs. The first advanced design of an ADS system is currently developed in SCK• CEN, Mol, Belgium: the Multi-purpose hYbrid Research Reactor for High-tech Applications (MYRRHA). Many European research programs support the design of MYRRHA. In the framework of the Euratom project ‘Thermal Hydraulics of Innovative nuclear Systems (THINS)’ a liquid-metal free-surface experiment is performed at the Karlsruhe Liquid Metal Laboratory (KALLA) of Karlsruhe Institute of Technology (KIT). The experiment investigates a full-scale model of the concentric free-surface spallation target of MYRRHA using Lead Bismuth Eutectic (LBE) as coolant. In parallel, numerical free surface models are developed and tested which are reviewed in the article. A volume-of-fluid method, a moving mesh model, a free surface model combining the Level-Set method with Large-Eddy Simulation model and a smoothed-particle hydrodynamics approach are investigated. Verification of the tested models is based on the experimental results obtained within the THINS project and on previous water experiments performed at the University Catholic de Louvain (UCL) within the Euratom project ‘EUROpean Research Programme for the TRANSmutation of High Level Nuclear Waste in Accelerator Driven System (EUROTRANS)’. The design of the target enables a high fluid velocity and a stable surface at the beam entry. The purpose of this paper is to present an overview of both experimental and numerical results obtained for free surface target characterization. Without entering in technical details, the status, the major achievements and lessons for the future with respect to

  1. Mechanisms of Chromium and Uranium Toxicity in Pseudomonas stutzeri RCH2 Grown under Anaerobic Nitrate-Reducing Conditions.

    Science.gov (United States)

    Thorgersen, Michael P; Lancaster, W Andrew; Ge, Xiaoxuan; Zane, Grant M; Wetmore, Kelly M; Vaccaro, Brian J; Poole, Farris L; Younkin, Adam D; Deutschbauer, Adam M; Arkin, Adam P; Wall, Judy D; Adams, Michael W W

    2017-01-01

    Chromium and uranium are highly toxic metals that contaminate many natural environments. We investigated their mechanisms of toxicity under anaerobic conditions using nitrate-reducing Pseudomonas stutzeri RCH2, which was originally isolated from a chromium-contaminated aquifer. A random barcode transposon site sequencing library of RCH2 was grown in the presence of the chromate oxyanion (Cr[VI][Formula: see text]) or uranyl oxycation (U[VI][Formula: see text]). Strains lacking genes required for a functional nitrate reductase had decreased fitness as both metals interacted with heme-containing enzymes required for the later steps in the denitrification pathway after nitrate is reduced to nitrite. Cr[VI]-resistance also required genes in the homologous recombination and nucleotide excision DNA repair pathways, showing that DNA is a target of Cr[VI] even under anaerobic conditions. The reduced thiol pool was also identified as a target of Cr[VI] toxicity and psest_2088 , a gene of previously unknown function, was shown to have a role in the reduction of sulfite to sulfide. U[VI] resistance mechanisms involved exopolysaccharide synthesis and the universal stress protein UspA. As the first genome-wide fitness analysis of Cr[VI] and U[VI] toxicity under anaerobic conditions, this study provides new insight into the impact of Cr[VI] and U[VI] on an environmental isolate from a chromium contaminated site, as well as into the role of a ubiquitous protein, Psest_2088.

  2. Mechanisms of Chromium and Uranium Toxicity in Pseudomonas stutzeri RCH2 Grown under Anaerobic Nitrate-Reducing Conditions

    Directory of Open Access Journals (Sweden)

    Michael P. Thorgersen

    2017-08-01

    Full Text Available Chromium and uranium are highly toxic metals that contaminate many natural environments. We investigated their mechanisms of toxicity under anaerobic conditions using nitrate-reducing Pseudomonas stutzeri RCH2, which was originally isolated from a chromium-contaminated aquifer. A random barcode transposon site sequencing library of RCH2 was grown in the presence of the chromate oxyanion (Cr[VI]O42− or uranyl oxycation (U[VI]O22+. Strains lacking genes required for a functional nitrate reductase had decreased fitness as both metals interacted with heme-containing enzymes required for the later steps in the denitrification pathway after nitrate is reduced to nitrite. Cr[VI]-resistance also required genes in the homologous recombination and nucleotide excision DNA repair pathways, showing that DNA is a target of Cr[VI] even under anaerobic conditions. The reduced thiol pool was also identified as a target of Cr[VI] toxicity and psest_2088, a gene of previously unknown function, was shown to have a role in the reduction of sulfite to sulfide. U[VI] resistance mechanisms involved exopolysaccharide synthesis and the universal stress protein UspA. As the first genome-wide fitness analysis of Cr[VI] and U[VI] toxicity under anaerobic conditions, this study provides new insight into the impact of Cr[VI] and U[VI] on an environmental isolate from a chromium contaminated site, as well as into the role of a ubiquitous protein, Psest_2088.

  3. Primary and secondary crystallization of modified hypoeutectic chromium cast iron

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2010-04-01

    Full Text Available The paper presents investigations of crystallization of modified hypoeutectic wear resistant chromium cast iron which contains carbon about 2% and chromium on three levels (12%, 18% and 25%. Three substances were applied to the modification ( boron carbide (B4C, ferroniobium (FeNb and mixture of ferroniobium and mischmetal (RE. The investigations of crystallization were conducted the DTA method in DTA-C and DTA-Is testers. The influence on the course of the process of primary and secondary crystallization was observed.

  4. Spectroscopic investigation of the charge dynamics of heavy ions penetrating solid and gaseous targets

    Energy Technology Data Exchange (ETDEWEB)

    Korostiy, S.

    2007-01-15

    This thesis presents the study of the slowing down process of fast heavy ions inside matter. In the framework of this research, the influence of the target density on the stopping process is investigated. Experiments on the interaction of {sup 48}Ca{sup 6+}-{sup 48}Ca{sup 10+} and {sup 26}Mg{sup 5+} ion beams with initial energies of 11.4 MeV/u and 5.9 MeV/u with solid and gaseous targets have been carried out. A novel diagnostic method, X-ray spectroscopy of K-shell projectile radiation, is used to determine the ion charge state in relation to its velocity during the penetration of fast heavy ions inside the stopping material. A spatially resolved analysis of the projectile and target radiation in solids is achieved for the first time. The application of low-density silica aerogels as stopping media provided a stretching of the ion stopping length by 20 - 100 times in comparison with solid quartz. The Doppler Effect observed on the projectile K-shell spectra is used to calculate the ion velocity in dependence on the ion penetration depth in the target material. A comparative analysis of K{sub {alpha}} spectra of fast heavy ions is performed in solid (silica aerogels) and gaseous targets (Ar and Ne gases) at the same ion energy. It is shown that the dominant role of collisions in dense matter leads to an increase of the effective ionization cross section at high ion velocity and suppression of the electron capture to the projectile ion excited states at low ion velocity. As a result, an increase of the ion charge state in dense matter is observed. The experimentally detected effects are interpreted with numerical calculations of the projectile population kinetics, which are in good agreement with measurements. (orig.)

  5. Using Peptide Aptamer Targeted Polymers as a Model Nanomedicine for Investigating Drug Distribution in Cancer Nanotheranostics.

    Science.gov (United States)

    Zhao, Yongmei; Houston, Zachary H; Simpson, Joshua D; Chen, Liyu; Fletcher, Nicholas L; Fuchs, Adrian V; Blakey, Idriss; Thurecht, Kristofer J

    2017-10-02

    Theranostics is a strategy that combines multiple functions such as targeting, stimulus-responsive drug release, and diagnostic imaging into a single platform, often with the aim of developing personalized medicine.1,2 Based on this concept, several well-established hyperbranched polymeric theranostic nanoparticles were synthesized and characterized as model nanomedicines to investigate how their properties affect the distribution of loaded drugs at both the cell and whole animal levels. An 8-mer peptide aptamer was covalently bound to the periphery of the nanoparticles to achieve both targeting and potential chemosensitization functionality against heat shock protein 70 (Hsp70). Doxorubicin was also bound to the polymeric carrier as a model chemotherapeutic drug through a degradable hydrazone bond, enabling pH-controlled release under the mildly acid conditions that are found in the intracellular compartments of tumor cells. In order to track the nanoparticles, cyanine-5 (Cy5) was incorporated into the polymer as an optical imaging agent. In vitro cellular uptake was assessed for the hyperbranched polymer containing both doxorubicin (DOX) and Hsp70 targeted peptide aptamer in live MDA-MB-468 cells, and was found to be greater than that of either the untargeted, DOX-loaded polymer or polymer alone due to the specific affinity of the peptide aptamer for the breast cancer cells. This was also validated in vivo with the targeted polymers showing much higher accumulation within the tumor 48 h postinjection than the untargeted analogue. More detailed assessment of the nanomedicine distribution was achieved by directly following the polymeric carrier and the doxorubicin at both the in vitro cellular level via compartmental analysis of confocal images of live cells and in whole tumors ex vivo using confocal imaging to visualize the distribution of the drug in tumor tissue as a function of distance from blood vessels. Our results indicate that this polymeric carrier shows

  6. Spectroscopic investigation of the charge dynamics of heavy ions penetrating solid and gaseous targets

    International Nuclear Information System (INIS)

    Korostiy, S.

    2007-01-01

    This thesis presents the study of the slowing down process of fast heavy ions inside matter. In the framework of this research, the influence of the target density on the stopping process is investigated. Experiments on the interaction of 48 Ca 6+ - 48 Ca 10+ and 26 Mg 5+ ion beams with initial energies of 11.4 MeV/u and 5.9 MeV/u with solid and gaseous targets have been carried out. A novel diagnostic method, X-ray spectroscopy of K-shell projectile radiation, is used to determine the ion charge state in relation to its velocity during the penetration of fast heavy ions inside the stopping material. A spatially resolved analysis of the projectile and target radiation in solids is achieved for the first time. The application of low-density silica aerogels as stopping media provided a stretching of the ion stopping length by 20 - 100 times in comparison with solid quartz. The Doppler Effect observed on the projectile K-shell spectra is used to calculate the ion velocity in dependence on the ion penetration depth in the target material. A comparative analysis of K α spectra of fast heavy ions is performed in solid (silica aerogels) and gaseous targets (Ar and Ne gases) at the same ion energy. It is shown that the dominant role of collisions in dense matter leads to an increase of the effective ionization cross section at high ion velocity and suppression of the electron capture to the projectile ion excited states at low ion velocity. As a result, an increase of the ion charge state in dense matter is observed. The experimentally detected effects are interpreted with numerical calculations of the projectile population kinetics, which are in good agreement with measurements. (orig.)

  7. 76 FR 31633 - Tin- and Chromium-Coated Steel Sheet from Japan; Institution of a Five-Year Review Concerning the...

    Science.gov (United States)

    2011-06-01

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-860 (Second Review)] Tin- and Chromium... Tin- and Chromium-Coated Steel Sheet from Japan AGENCY: United States International Trade Commission... the antidumping duty order on tin- and chromium-coated steel sheet from Japan would be likely to lead...

  8. Acute Severe Chromium Poisoning After Dermal Exposure to Hexavalent Chromium

    Directory of Open Access Journals (Sweden)

    Chun-Chi Lin

    2009-04-01

    Full Text Available Severe acute chromium poisoning related to dermal involvement has rarely been reported in the literature. We report a case of acute severe chromium poisoning through skin exposure as a result of a chemical burn of 15% of the body surface area and multiple organ failure after short-term exposure. Medical interventions, including mechanical ventilation, continuous venovenous hemofiltration, and plasmapheresis were performed. In addition, a chelating agent, dimercapto-propane sulfonic acid, was infused intravenously, combined with intravenous N-acetylcysteine and ascorbic acid as adjuvant therapy. The patient was discharged on day 33 without long-term sequelae. The consequence of transdermal exposure of hexavalent chromium should not be overlooked.

  9. Specification for corrosion-resisting chromium and chromium-nickel steel covered welding electrodes

    International Nuclear Information System (INIS)

    Anon.

    1983-01-01

    This specification prescribes requirements for covered corrosion-resisting chromium and chromium-nickel steel electrodes. These electrodes normally are used for shielded metal arc welding, and include those alloy steels designated as corrosion or heat-resisting chromium-nickel steels in which chromium exceeds 4.0 percent and nickel does not exceed 50.0 percent

  10. Investigation of residual nuclei in spallation produced in lead and tungsten thin targets and in a thick lead target

    International Nuclear Information System (INIS)

    Ducauze, Marie

    2001-01-01

    As spallation has a lot of potential applications, and aroused many theoretical works and phenomenological modelling, this research thesis deals with the measurement of residual nucleus cross sections in lead and tungsten targets irradiated by protons with intermediate energy level. Experiments have been performed on the SATURNE accelerator. With respect to spallation properties, two measurement types are addressed: measurements in thin targets to study the nucleon-nucleus reactions, and measurements in thick targets to study particle transport through matter. After a brief presentation of the experimental conditions, the author presents the method used to analyse gamma radiation spectra: spectrum deconvolution, time analysis, identification of created nuclei and extraction of residual production cross-sections. An overview of simulation code is given. Results of cross-section measurements are discussed and commented for the case of thin lead and tungsten targets. They are also compared with those obtained with the HETC code (High Energy Transport Code). Data obtained with a thick lead target are presented, interpreted and compared with those obtained with the TIERCE code

  11. Chemical Investigations of ISOL target units for carbon and nitrogen beams

    CERN Document Server

    Franberg, H; Gäggeler, H W; Köster, U

    2006-01-01

    Radioactive Ion Beams (RIB) are of significant interest in a number of applications. ISOL (Isotope Separation On Line) facilities provide RIB with high beam intensities and good beam quality. An atom that is produced within the ISOL target will first diffuse out from the target material. During the effusion towards the transfer line and into the ion source the many contacts with the surrounding surfaces may cause unacceptable delays in the transport and, hence, losses of the shorter-lived isotopes. We performed systematic chemical investigations of adsorption in a temperature and concentration regime relevant for ISOL targets and ion source units, with regard to COx and NOx on Al2O3 and SiO2. These materials are potential construction materials for the above mentioned areas. Off-line and on-line tests have been performed using a gas thermo-chromatography set-up with radioactive tracers. The experiments were performed at the PROTRAC facility at Paul Scherrer Institute in Villigen, Switzerland.

  12. EURISOL Multi-MW Target: Investigation of the hydrodynamics of liquid metal (Hg) jet

    CERN Document Server

    Freibergs, J

    In order to develop a windowless target it is necessary to investigate the hydrodynamics of liquid metal (Hg) jet. On the basis of the schematic layout of a high-power target module presented in Ref. [2], and the parameters of the windowless target (speed of the mercury jet up to 30 m/s, diameter of jet 10-20 mm and length of jet about 1 m), a first estimation of the parameters of the main components of a Hg-loop has been obtained by the Institute of Physics, University of Latvia. A preliminary engineering design of a functional Hg-loop to be constructed soon is also proposed. A simplified water stand has been developed with the ability of testing different Hg-nozzle configurations. The tests carried out showed that the kinetic energy of the jet is so high that the coaxial water flow at contact point is transformed into small bubbles (spray). The characteristics of the jet were shown to depend on the pressure of the stand.

  13. Chromium Salen Mediated Alkene Epoxidation

    DEFF Research Database (Denmark)

    Petersen, Kaare Brandt; Norrby, Per-Ola; Daly, Adrian M.

    2002-01-01

    The mechanism of alkene epoxidation by chromium(v) oxo salen complexes has been studied by DFT and experimental methods. The reaction is compared to the closely related Mn-catalyzed process in an attempt to understand the dramatic difference in selectivity between the two systems. Overall......, the studies show that the reactions have many similarities, but also a few critical differences. In agreement with experiment, the chromium system requires a change from low- to high-spin in the catalytic cycle, whereas the manganese system can proceed either with spin inversion or entirely on the high......-spin surface. The low-spin addition of metal oxo species to an alkene leads to an intermediate which forms epoxide either with a barrier on the low-spin surface or without a barrier after spin inversion. Supporting evidence for this intermediate was obtained by using vinylcyclopropane traps. The chromium...

  14. Sorption of chromium(VI) and chromium(III) on aluminium hydroxide

    International Nuclear Information System (INIS)

    Music, S.

    1986-01-01

    Factors that influence the sorption of Cr(VI) and Cr(III) on aluminium hydroxide were investigated. The sorption of chromates decreases as the pH of the suspension increases. The mechanism of CrOsub(4)sup(2-) sorption was interpreted in terms of reactions between chromates and -OH and/or Hsub(2)O groups at the hydroxide/liquid interface. It was shown that chromates are more tightly sorbed on aluminium hydroxide compared to other anions, e.g. chlorides. On the other hand, specifically absorbed anions, such as molybdates, compete strongly with chromates for the sorption sites. The sorption of chromium(III) increases with the pH of the suspension. Also, the sorption of chromium(III) is suppressed in the presence of citrate ions. The best conditions for the fixation of Cr(VI) and Cr(III) by aluminium hydroxide are presented. (author)

  15. Structure and magnetic properties of chromium doped cobalt molybdenum nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Guskos, Niko; Żołnierkiewicz, Grzegorz; Typek, Janusz; Guskos, Aleksander [Institute of Physics, Faculty of Mechanical Engineering and Mechatronics, West Pomeranian University of Technology, Szczecin, Piastów 48, 70-311 Szczecin (Poland); Adamski, Paweł; Moszyński, Dariusz [Institute of Inorganic Chemical Technology and Environment Engineering, West Pomeranian University of Technology, Szczecin, Pułaskiego 10, 70-322 Szczecin (Poland)

    2016-09-15

    Four nanocomposites containing mixed phases of Co{sub 3}Mo{sub 3}N and Co{sub 2}Mo{sub 3}N doped with chromium have been prepared. A linear fit is found for relation between Co{sub 2}Mo{sub 3}N and chromium concentrations. The magnetization in ZFC and FC modes at different temperatures (2–300 K) and in applied magnetic fields (up to 70 kOe) have been investigated. It has been detected that many magnetic characteristics of the studied four nanocomposites correlate not with the chromium concentration but with nanocrystallite sizes. The obtained results were interpreted in terms of magnetic core-shell model of a nanoparticle involving paramagnetic core with two magnetic sublattices and a ferromagnetic shell related to chromium doping. - Highlights: • A new chromium doped mixed Co-Mn-N nanocomposites were synthesized. • Surface ferromagnetism was detected in a wide temperature range. • Core-shell model was applied to explain nanocomposites magnetism.

  16. Chromium Uptake Efficiency of Spinacea olaracea from ...

    African Journals Online (AJOL)

    The aim of the study was to evaluate the uptake of chromium by Spinacea olaracea and its accumulation in roots and shoots of plants grown in pots at various concentrations of chromium (30, 60, 90,120,150 mg/l). The results revealed that the levels of chromium accumulation in roots and shoots were higher at minimum ...

  17. Investigation of magnetic nanoparticle targeting in a simplified model of small vessel aneurysm

    Energy Technology Data Exchange (ETDEWEB)

    Mirzababaei, S.N. [Department of Chemical Engineering, Noshirvani Babol University of Technology, Babol (Iran, Islamic Republic of); Gorji, Tahereh B., E-mail: gorji.tahereh@stu.nit.ac.ir [Department of Mechanical Engineering, Noshirvani Babol University of Technology, Babol (Iran, Islamic Republic of); Baou, M.; Gorji-Bandpy, M. [Department of Mechanical Engineering, Noshirvani Babol University of Technology, Babol (Iran, Islamic Republic of); Fatouraee, Nasser [Department of Biomedical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2017-03-15

    An in simulacra study was conducted to investigate the capture efficiency (CE) of magnetic nanoparticles (MNPs) in aneurysm model, under the effect of a bipolar permanent magnetic system positioned at the vicinity of the model vessel. The bipolar magnetic system with an active space of 9 cm was designed by FEMM software. The MNPs were magnetite nanoparticles synthesized by the hydrothermal method which were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope and magnetometer measurements. Ferrofluid velocity, magnetic field strength, and aneurysm volume all proved to be important parameters which affect the capturing of MNPs. Overall, the results of this in simulacra study confirmed the effectiveness of magnetic targeting for possible aneurysm embolization. - Highlights: • An in simulacra investigation of the magnetic targeting in mechanical aneurysm embolization was conducted. • A bipolar permanent magnetic system with an active space of 9 cm was designed by FEMM software. • Magnetic nanofluid was synthetized and applied in an experimental setup to study the effect of different flow, magnetic field and geometry parameters on the capture efficiency of the magnetic particles acting as a dug carrier agent.

  18. Investigator-initiated trials of targeted oncology agents: why independent research is at risk?

    Science.gov (United States)

    Bergmann, L; Berns, B; Dalgleish, A G; von Euler, M; Hecht, T T; Lappin, G L; Reed, N; Palmeri, S; Smyth, J; Embacher-Aichorn, S; Zwierzina, H

    2010-08-01

    Drug development traditionally has relied upon the complementary contributions of clinicians and scientists at academic institutions and at pharmaceutical companies. Greater regulatory burdens, increased bureaucratic requirements, restricted reimbursement, and spiralling research and development costs are exerting pressure on the drug development pipeline. The result is a de-emphasis of exploratory research, particularly independent academic research, despite its proven value in identifying new drug targets and developing innovative cancer therapies. An expert panel assembled by the Biotherapy Development Association-a nonprofit international forum for academic and industry researchers, patients, and government regulatory and postregulatory agencies-examined the growing schism between academia and industry and identified several causes of declining academic research. The authors propose solutions to sustain investigator-initiated research and provide a new model whereby expert organisations provide a forum for academia and industry to plan studies within a regulatory framework to support licensure/authorisation and reimbursement for new molecularly targeted agents and biomarkers. Investigator-initiated trials have led to the discovery and development of innovative, safe, and effective cancer treatments. To ensure that such research continues, action will be required on the parts of legislative and regulatory bodies, industry, universities, patient advocacy organisations, and preclinical and clinical academic scientists.

  19. Chromium in urothelial carcinoma of the bladder.

    Science.gov (United States)

    Golabek, Tomasz; Socha, Katarzyna; Kudelski, Jacek; Darewicz, Barbara; Markiewicz-Zukowska, Renata; Chlosta, Piotr; Borawska, Maria

    2017-12-23

    Many epidemiological and experimental studies report a strong role of chemical carcinogens in the etiology of bladder cancer. However, the involvement of heavy metals in tumourigenesis of urothelial carcinoma of the bladder has been poorly investigated. Therefore, the aim of this study was to examine the relationship between chromium (Cr) and bladder cancer. Chromium concentration in two 36-sample series of bladder cancer tissue and sera from patients with this neoplasm were matched with those of a control group. The amount of trace elements in every tissue sample was determined using atomic absorption spectrometry. This was correlated with tumour stage. While the median chromium concentration levels reached statistically higher values in the bladder cancer tissue, compared with the non-cancer tissue (99.632ng/g and 33.144ng/g, respectively; p<0.001), the median Cr levels in the sera of the patients with this carcinoma showed no statistical difference when compared to those of the control group (0.511μg/l and 0.710μg/l, respectively; p=0.408). The median levels of Cr in the bladder tissue, depending on the stage of the tumour, compared with the tissue without the neoplasm, observed the same relationship for both non-muscle invasive and muscle-invasive tumours (p<0.001 and p<0.01, respectively). This study shows that patients with urothelial carcinoma of the bladder had higher tissue Cr levels than people without tumour, while no difference was found in the Cr serum levels between the two groups of patients under investigation.

  20. Portable x-ray fluorescence for the analysis of chromium in nail and nail clippings

    International Nuclear Information System (INIS)

    Fleming, David E.B.; Ware, Chris S.

    2017-01-01

    Assessment of chromium content in human nail or nail clippings could serve as an effective biomarker of chromium status. The feasibility of a new portable x-ray fluorescence (XRF) approach to chromium measurement was investigated through analysis of nail and nail clipping phantoms. Five measurements of 180 s (real time) duration were first performed on six whole nail phantoms having chromium concentrations of 0, 2, 5, 10, 15, and 20 µg/g. Using nail clippers, these phantoms were then converted to nail clippings, and assembled into different mass groups of 20, 40, 60, 80, and 100 mg for additional measurements. The amplitude of the chromium Kα characteristic x-ray energy peak was examined as a function of phantom concentration for all measurement conditions to create a series of calibration lines. The minimum detection limit (MDL) for chromium was also calculated for each case. The chromium MDL determined from the whole nail intact phantoms was 0.88±0.03 µg/g. For the clipping phantoms, the MDL ranged from 1.2 to 3.3 µg/g, depending on the mass group analyzed. For the 40 mg clipping group, the MDL was 1.2±0.1 µg/g, and higher mass collections did not improve upon this result. This MDL is comparable to chromium concentration levels seen in various studies involving human nail clippings. Further improvements to the portable XRF technique would be required to detect chromium levels expected from the lower end of a typical population. - Highlights: • Portable x-ray fluorescence (XRF) was explored as a technique to assess levels of chromium in human nails or nail clippings. • Results were found to depend on the mass of clipping sample provided. • Minimum detection limits for chromium were similar to concentration levels found in previous studies of human nail clippings.

  1. Biosorption of hexavalent chromium (chromium (VI) ion from ...

    African Journals Online (AJOL)

    taye

    2015-04-01

    Apr 1, 2015 ... industrial discharges (Wang and Cheng, 2009). Hexavalent Chromium (Cr (VI) is a by-product released into the aquatic environment by many industrial activities such as leather tanning, chrome plating, stainless steel welding, pigment production and nuclear weapon production (Gonzalez et al., 2003).

  2. Impurities in chromium deposits produced by electroplating and physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dini, J.W.

    1994-05-01

    Impurity contents in electrodeposited (hexavalent and trivalent) chromium deposits and physically vapor deposited (thermal evaporation, electron beam evaporation and rf-sputtering) were compared. Oxygen is the key impurity obtained in electrodeposited films but it can be minimized in hexavalent plating solutions by operating at high temperature, e. g., 85 C. Electrodeposits produced in trivalent chromium plating solutions and physically vapor deposited films have much higher oxygen contents than electrodeposits produced in hexavalent chromium solutions operated at temperatures around 85 C. Depending on the target material used for physically vapor deposited films, these films can also have high amounts of other impurities.

  3. Environmental biochemistry of chromium.

    Science.gov (United States)

    Losi, M E; Amrhein, C; Frankenberger, W T

    1994-01-01

    Chromium is a d-block transitional element with many industrial uses. It occurs naturally in various crustal materials and is discharged to the environment as industrial waste. Although it can occur in a number of oxidation states, only 3+ and 6+ are found in environmental systems. The environmental behavior of Cr is largely a function of its oxidation state. Hexavalent Cr compounds (mainly chromates and dichromates) are considered toxic to a variety of terrestrial and aquatic organisms and are mobile in soil/water systems, much more so than trivalent Cr compounds. This is largely because of differing chemical properties: Hexavalent Cr compounds are strong oxidizers and highly soluble, while trivalent Cr compounds tend to form relatively inert precipitates at near-neutral pH. The trivalent state is generally considered to be the stable form in equilibrium with most soil/water systems. A diagram of the Cr cycle in soils and water is given in Fig. 6 (Bartlett 1991). This illustration provides a summary of environmentally relevant reactions. Beginning with hexavalent Cr that is released into the environment as industrial waste, there are a number of possible fates, including pollution of soil and surface water and leaching into groundwater, where it may remain stable and, in turn, can be taken up by plants or animals, and adsorption/precipitation, involving soil colloids and/or organic matter. Herein lies much of the environmental concern associated with the hexavalent form. A portion of the Cr(VI) will be reduced to the trivalent form by inorganic electron donors, such as Fe2+ and S2-, or by bioprocesses involving organic matter. Following this conversion, Cr3+ can be expected to precipitate as oxides and hydroxides or to form complexes with numerous ligands. This fraction includes a vast majority of global Cr reserves. Soluble Cr3+ complexes, such as those formed with citrate, can undergo oxidation when they come in contact with manganese dioxide, thus reforming

  4. The electrochemistry of chromium, chromium-boron and chromium-phosphorus alloys

    International Nuclear Information System (INIS)

    Moffat, T.P.; Ruf, R.R.; Latanision, R.M.

    1987-01-01

    It is fairly well established that chromium-metalloid interactions represent the key to understanding the remarkable corrosion behavior of TM-Cr-M glasses; (Fe, Ni, Co,...)-Cr-(P, Si, C, S). The character and kinetics of passive film growth on the glasses are being studied ni order to assess the role of the film former, chromium, and the metalloids in the passivation process. A series of thin film microcrystalline chromium, Cr-B and Cr-P binary alloys have been fabricated by physical vapor deposition techniques. Vacuum melted conventionally processed chromium has also been studied. Examination of these materials in lM H/sub 2/SO/sub 4/ and lM HCl by voltammetry, potentiostatic and impedance techniques yields the following conclusion: 1. Pure chromium with a grain size varying from < 400 A to 0.5 mm exhibits no well defined differences in electrochemical behavior in lM H/sub 2/SO/sub 4/. 2. The tremendous corrosion resistance of Cr-B alloys has been confirmed. 3. The beneficial effects observed for boron alloyed with chromium may be considered surprising in view of the neutral/negative influence of alloying boron with iron, i.e. Fe/sub 80/B/sub 20/. 4. The interaction of the electrochemistry of the metalloid constituent with that of the transition base element determines the corrosion behavior. 5. Preliminary work with Cr-P alloys indicates that certain compositions exhibit promising properties - certain films were found to be intact after two days of immersion in concentrated HCl. Further work is in progress

  5. FP corrosion dependence on carbon and chromium content in Fe-Cr steel

    International Nuclear Information System (INIS)

    Sasaki, Koei; Tanigaki, Takanori; Fukumoto, Ken-ichi; Uno, Masayoshi

    2015-01-01

    In an attempt to investigate Cs or Cs-Te corrosion dependence on chromium or carbon content in Fe-Cr steel, cesium and Cs-Te corrosion test were performed to three specimens, Fe-9Cr-0C, Fe-9Cr-0.14C and Fe-13Cr-0.14C, for 100 hours at 973K in simulated high burn-up fuel pin environment. Cesium corrosion depth has no dependence on chromium or carbon content in Fe-Cr steel. Cs-Te corrosion was appeared in only Fe-13Cr-0.14C which has chromium carbides ranged along grain boundary. Appearance of the Cs-Te corrosion was determined by distribution or arrangement of chromium carbides which depends on chromium and carbon content. (author)

  6. Polymorphisms of Selected DNA Repair Genes and Lung Cancer in Chromium Exposure.

    Science.gov (United States)

    Halasova, E; Matakova, T; Skerenova, M; Krutakova, M; Slovakova, P; Dzian, A; Javorkova, S; Pec, M; Kypusova, K; Hamzik, J

    2016-01-01

    Chromium is a well-known mutagen and carcinogen involved in lung cancer development. DNA repair genes play an important role in the elimination of genetic changes caused by chromium exposure. In the present study, we investigated the polymorphisms of the following DNA repair genes: XRCC3, participating in the homologous recombination repair, and hMLH1 and hMSH2, functioning in the mismatch repair. We focused on the risk the polymorphisms present in the development of lung cancer regarding the exposure to chromium. We analyzed 106 individuals; 45 patients exposed to chromium with diagnosed lung cancer and 61 healthy controls. Genotypes were determined by a PCR-RFLP method. We unravelled a potential for increased risk of lung cancer development in the hMLH1 (rs1800734) AA genotype in the recessive model. In conclusion, gene polymorphisms in the DNA repair genes underscores the risk of lung cancer development in chromium exposed individuals.

  7. Iron-nickel-chromium alloys

    International Nuclear Information System (INIS)

    Karenko, M.K.

    1981-01-01

    A specification is given for iron-nickel-chromium age-hardenable alloys suitable for use in fast breeder reactor ducts and cladding, which utilize the gamma-double prime strengthening phase and are characterized in having a delta or eta phase distributed at or near grain boundaries. A range of compositions is given. (author)

  8. Chromium isotope uptake in carbonates

    DEFF Research Database (Denmark)

    Rodler, Alexandra

    Chromium (Cr) is a redox sensitive element potentially capable of tracing fine-scale fluctuations of the oxygenation of Earth’s early surface environments and seawater. The Cr isotope composition of carbonates could perhaps be used as paleo-redox proxy to elucidate changes in the geological past...

  9. Chromium Chemistry in the Subsurface

    Science.gov (United States)

    Chromium (VI) (Cr) is carcinogenic and a threat to human and ecological health. There are adequate and acceptable methods to characterize and assess Cr contaminated sites. Cr chemistry in the environment is well understood. There are documented methods to address Cr contaminat...

  10. Predicting chromium (VI) adsorption rate in the treatment of liquid ...

    African Journals Online (AJOL)

    Administrator

    flocculation effluent of liquid-phase oil-based drill-cuttings has been investigated in terms of contact time and initial chromium (VI) ion ... currently being done by oil drilling and exploration and production (E and P) waste .... model, the separation factor r, according to Calvo et al (2001) cited in Rozada et al. (2005), may be ...

  11. Removal of Lead and Chromium from Aqueous Solution onto ...

    African Journals Online (AJOL)

    OLUWASOGO

    pH, initial concentration as well as adsorbent dosage on the removal efficiency of both metal ions was investigated via batch adsorption. ... lead and chromium in wastewater as indicated by the United. States Environmental Protection ... electro dialysis, membrane separations, reverse osmosis and solvent extraction in the ...

  12. Chromium-induced accumulation of peroxide content, stimulation of ...

    African Journals Online (AJOL)

    Chromium (Cr)-induced oxidative damage and changes in contents of chlorophyll, protein, peroxide and malondialdehyde (MDA) and activities of enzymatic antioxidants were investigated in 4-day-old green gram (Vigna radiata L. cv. Wilczek) seedlings. Cr increased the contents of peroxide and MDA but decreased the ...

  13. Selective removal of chromium from sulphuric acid leach liquor of ...

    African Journals Online (AJOL)

    The selective removal of chromium, a trace impurity that degrades the whiteness of titanium(IV) oxide pigments, from sulphuric acid leach liquor of ilmenite, was investigated by solvent extraction with xylene solutions of trioctylamine. Important factors of commercial significance affecting the extraction operation have been ...

  14. Chromium in Drinking Water: Association with Biomarkers of Exposure and Effect

    Science.gov (United States)

    Sazakli, Eleni; Villanueva, Cristina M.; Kogevinas, Manolis; Maltezis, Kyriakos; Mouzaki, Athanasia; Leotsinidis, Michalis

    2014-01-01

    An epidemiological cross-sectional study was conducted in Greece to investigate health outcomes associated with long-term exposure to chromium via drinking water. The study population consisted of 304 participants. Socio-demographics, lifestyle, drinking water intake, dietary habits, occupational and medical history data were recorded through a personal interview. Physical examination and a motor test were carried out on the individuals. Total chromium concentrations were measured in blood and hair of the study subjects. Hematological, biochemical and inflammatory parameters were determined in blood. Chromium in drinking water ranged from Chromium levels in blood (median 0.32 μg·L−1, range chromium exposure dose via drinking water, calculated from the results of the water analyses and the questionnaire data, showed associations with blood and hair chromium levels and certain hematological and biochemical parameters. Groups of subjects whose hematological or biochemical parameters were outside the normal range were not correlated with chromium exposure dose, except for groups of subjects with high triglycerides or low sodium. Motor impairment score was not associated with exposure to chromium. PMID:25268509

  15. Treatment of chromium contaminated soil using bioremediation

    Science.gov (United States)

    Purwanti, Ipung Fitri; Putri, Tesya Paramita; Kurniawan, Setyo Budi

    2017-11-01

    Chromium contamination in soil occurs due to the disposal of chromium industrial wastewater or sludge that excess the quality standard. Chromium concentration in soil is ranged between 1 to 300 mg/kg while the maximum health standard is 2.5 mg/kg. Bioremediation is one of technology that could be used for remediating heavy metal contamination in soil. Bacteria have an ability to remove heavy metal from soil. One bacteria species that capable to remove chromium from soil is Bacillus subtilis. The aim of this research was to know the chromium removal percentage in contaminated soil by Bacillus subtilis. Artificial chromium contaminated soil was used by mixing 425gram sand and chromium trichloride solution. Concentration of chromium added into the spiked soil were 50, 75, and 100 mg/L. During 14 days, pH, soil temperature and soil moisture were tested. Initial and final number of bacterial colony and chromium concentration analysed. The result showed that the highest percentage of chromium removal was 11% at a chromium concentration of 75 mg/L

  16. Application of Targeted Metabolomics to Investigate Optimum Growing Conditions to Enhance Bioactive Content of Strawberry.

    Science.gov (United States)

    Akhatou, Ikram; Sayago, Ana; González-Domínguez, Raúl; Fernández-Recamales, Ángeles

    2017-11-01

    A simple, sensitive, and rapid assay based on liquid chromatography coupled to tandem mass spectrometry was designed for simultaneous quantitation of secondary metabolites in order to investigate the influence of variety and agronomic conditions on the biosynthesis of bioactive compounds in strawberry. For this purpose, strawberries belonging to three varieties with different sensitivity to environmental conditions ('Camarosa', 'Festival', 'Palomar') were grown in a soilless system under multiple agronomic conditions (electrical conductivity, substrate type, and coverage). Targeted metabolomic analysis of polyphenolic compounds, combined with advanced chemometric methods based on learning machines, revealed significant differences in multiple bioactives, such as chlorogenic acid, ellagic acid rhamnoside, sanguiin H10, quercetin 3-O-glucuronide, catechin, procyanidin B2, pelargonidin 3-O-glucoside, cyanidin 3-O-glucoside, and pelargonidin 3-O-rutinoside, which play a pivotal role in organoleptic properties and beneficial healthy effects of these polyphenol-rich foods.

  17. Pentanol-based target material with polarized protons

    International Nuclear Information System (INIS)

    Bunyatova, E.I.

    1992-01-01

    1-pentanol is a promising material for a target with polarized protons owing to its high resistance to radiation damage. To develop the target, the solutions of 1-pentanol or 2-pentanol with complexes of pentavalent chromium ware investigated. The material based EHBA-Cr(V) solution in a glass-like matrix, consisting of 1-pentanol, 3-pentanol and 1,2-propanediol, was proposed as a target material. It was investigated by the electron paramagnetic resonance and differential scanning calorimetry methods. 24 refs.; 3 figs.; 1 tab

  18. The rf-power dependences of the deposition rate, the hardness and the corrosion-resistance of the chromium nitride film deposited by using a dual ion beam sputtering system

    International Nuclear Information System (INIS)

    Lim, Jongmin; Lee, Chongmu

    2006-01-01

    The hexavalent chromium used in chromium plating is so toxic that it is very hazardous to human body and possibly causes cancer in humans. Therefore, it is indispensable to develop an alternative deposition technique. Dependences of the deposition rate, the phases, the hardness, the surface roughness and the corrosion-resistance of CrN x deposited on the high speed steel substrate by using a dual ion beam sputtering system on the rf-power were investigated to see the feasibility of sputtering as an alternative technique for chromium plating. The dual ion beam sputtering system used in this study was designed in such a way as the primary argon ion beam and the secondary nitrogen ion beam are injected toward the target and the substrate, respectively so that the chromium atoms at the chromium target surface may not nearly react with nitrogen atoms. The hardness and the surface roughness were measured by a micro-Vicker's hardness tester and an atomic force microscope (AFM), respectively. X-ray diffraction analyses were performed to identify phases in the films. The deposition rate of CrN x depends more strongly upon the rf-power for argon ion beam than that for nitrogen ion beam. The hardness of the CrN x film is highest when the volume percent of the Cr 2 N phase in the film is highest. Amorphous films are obtained when the rf-power for nitrogen ion beam is much higher than that for argon ion beam. The CrN x film deposited by using the sputtering technique under the optimal condition provides corrosion-resistance comparable to that of the electroplated chromium

  19. Opto-electronic properties of chromium doped indium-tin-oxide films deposited at room temperature

    International Nuclear Information System (INIS)

    Chang Weiche; Lee Shihchin; Yang Chihhao; Lin Tienchai

    2008-01-01

    Indium-tin-oxide (ITO) doped chromium films were deposited on Corning 7059 glass prepared by radio frequency (RF) magnetron sputtering under various levels of sputtering power for the chromium target. Experimental results show that the surface roughness slightly decreases by co-sputtering Cr. The pure ITO films deposited at room temperature were amorphous-like. At 15 W of chromium target power, the structure of ITO: Cr film mainly consists of (2 2 2) crystallization plane, with minority of (2 1 1), (4 4 0), (6 6 2) crystallization planes. The carrier concentration of the ITO films increases with increasing the doping of chromium, however the mobility of the carrier decreases. When the sputtering power of the chromium target is at 7.5 W, there has a maximum carrier mobility of 27.3 cm 2 V -1 s -1 , minimum carrier concentration of 2.47 x 10 20 cm -3 , and lowest resistivity of 7.32 x 10 -4 Ω cm. The transmittance of all the chromium doped ITO films at the 300-800 nm wavelength region in this experiment can reach up to 70-85%. In addition, the blue shift of UV-Vis spectrum is not observed with the increase of carrier concentration

  20. Reduction of hexavalent chromium by ferrous iron: A process of chromium isotope fractionation and its relevance to natural environments

    DEFF Research Database (Denmark)

    Døssing, Lasse Nørbye; Dideriksen, Knud; Stipp, Susan Louise Svane

    2011-01-01

    Stable chromium (Cr) isotopes can be used as a tracer for changing redox conditions in modern marine systems and in the geological record. We have investigated isotope fractionation during reduction of Cr(VI)aq by Fe(II)aq. Reduction of Cr(VI)aq by Fe(II)aq in batch experiments leads to significant...

  1. Chromium in aqueous nitrate plutonium process streams: Corrosion of 316 stainless steel and chromium speciation

    International Nuclear Information System (INIS)

    Smith, W.H.; Purdy, G.

    1994-01-01

    According to the measurements made in this study, the only situation in which chromium (+6) could exist in a plutonium process solution is one in which a feed containing chromium is dissolved in a glass pot dissolver in high nitric acid concentration and at high temperature. But when the resulting feed is prepared for ion exchange, the chemical treatment reduces chromium to the +3 state. Any solution being processed through the evaporator will only contain chromium in the +3 state and any chromium salts remaining in the evaporator bottoms will be chromium +3 salts

  2. Clinical investigation of TROP-2 as an independent biomarker and potential therapeutic target in colon cancer.

    Science.gov (United States)

    Zhao, Peng; Yu, Hai-Zheng; Cai, Jian-Hui

    2015-09-01

    Colon cancer is associated with a severe demographic and economic burden worldwide. The pathogenesis of colon cancer is highly complex and involves sequential genetic and epigenetic mechanisms. Despite extensive investigation, the pathogenesis of colon cancer remains to be elucidated. As the third most common type of cancer worldwide, the treatment options for colon cancer are currently limited. Human trophoblast cell‑surface marker (TROP‑2), is a cell‑surface transmembrane glycoprotein overexpressed by several types of epithelial carcinoma. In addition, TROP‑2 has been demonstrated to be associated with tumorigenesis and invasiveness in solid types of tumor. The aim of the present study was to investigate the protein expression of TROP‑2 in colon cancer tissues, and further explore the association between the expression of TROP‑2 and clinicopathological features of patients with colon cancer. The expression and localization of the TROP‑2 protein was examined using western blot analysis and immunofluorescence staining. Finally, the expression of TROP‑2 expression was correlated to conventional clinicopathological features of colon cancer using a χ2 test. The results revealed that TROP‑2 protein was expressed at high levels in the colon cancer tissues, which was associated with the development and pathological process of colon cancer. Therefore, TROP‑2 may be used as a biomarker to determine the clinical prognosis, and as a potential therapeutic target in colon cancer.

  3. Responses of endogenous proline in rice seedlings under chromium exposure

    Directory of Open Access Journals (Sweden)

    X.Z. Yu

    2016-12-01

    Full Text Available Hydroponic experiments were performed to exam the dynamic change of endogenous proline in rice seedlings exposed to potassium chromate chromium (VI or chromium nitrate chromium (III. Although accumulation of both chromium species in rice seedlings was obvious, more chromium was detected in plant tissues of rice seedlings exposed to chromium (III than those in chromium (VI, majority being in roots rather than shoots. Results also showed that the accumulation capacity of chromium by rice seedlings was positively correlated to chromium concentrations supplied in both chromium variants and the accumulation curve depicted an exponential trend in both chromium treatments over the entire period of exposure. Proline assays showed that both chromium variants induced the change of endogenous proline in shoots and roots of rice seedlings. Chromium (VI of 12.8 mg/L increased proline content significantly (p

  4. Proteomic Responses of BEAS-2B Cells to Nontoxic and Toxic Chromium: Protein Indicators of Cytotoxicity Conversion

    Science.gov (United States)

    Hexavalent chromium (Cr (VI)) is an environmental human carcinogen which primarily targets lungs. Among a variety of toxic mechanisms, disruption of biological pathways via translational and post-translational modifications represents a key mechanism through which Cr (VI) induces...

  5. Carbon, chromium and molybdenum contents

    International Nuclear Information System (INIS)

    Sinatora, A; Goldenstein, H.; Mei, P.R.; Albertin, E.; Fuoco, R.; Mariotto, C.L.

    1992-01-01

    This work describes solidification experiments on white cast iron, with 15 and 20% of chromium, 2.3, 3.0 and 3.6 % of carbon and 0.0, 1.5 and 2.5 % of molybdenum in test de samples with 30 mm diameter. Measurements were performed on the austenite and eutectic formation arrests, the number of the eutectic carbide particles relative to the total and the eutectic volumes, and the volume fraction of the primary austenite

  6. Investigation of spherical and cylindrical catural Iridium targets by photonuclear reaction

    Science.gov (United States)

    Korkmaz, Mehmet Emin; Agar, Osman; Yigit, Mustafa

    2017-09-01

    In this study, natural iridium consisting of Ir-191 and Ir-193 isotopes has been irradiated with 21 MeV photons. The distribution of photons, electrons and neutrons fluxes in the spherical and cylindrical natural iridium target have been calculated using MCNPX 2.7.0 Monte Carlo code. The intensity of the photon fluxes on both targets has been compared to the 106 particle story by showing them as mesh and optimizing the two targets.

  7. THE DISTRIBUTION OF ZINC, NICKEL AND CHROMIUM IN BIOMASS OF FERTILIZED Salix viminalis L.

    Directory of Open Access Journals (Sweden)

    Dorota Kalembasa

    2014-10-01

    Full Text Available The distribution of zinc, nickel and chromium in the leaves and branches of three varieties of Salix viminalis differentiated fertilized was investigated. The biomass of Salix viminalis was harvested for investigation in the first and second year of application of mineral fertilizers and waste activate sludge in doses which contained 50, 150 and 200 kg of total nitrogen. The content of investigated metals was significantly differentiated upon the part of plant and fertilization. The amount of zinc, nickel and chromium were higher in leaves than in branches. The biomass of Salix viminalis contained the highest amount of zinc and the lowest of chromium. The highest content of zinc was determined in the biomass of Salix purpurea but lowest nickel and chromium in S. alba. The fertilization had differentiated influence upon the content of determined elements.

  8. Inoculation of chromium white cast iron

    Directory of Open Access Journals (Sweden)

    D. Kopyciński

    2009-01-01

    Full Text Available It has been proved that an addition of boron carbide introduced as an inoculant to the chromium white cast iron changes the structureof castings. Castings after inoculation revealed a different structure with numerous grains. Primary precipitates of chromium carbide also appeared, reducing the mechanical properties of as-cast parts. Properly established heat treatment regime makes chromium iron castings regain their, originally high, mechanical properties.

  9. A homoleptic chromium(iii) carboxylate.

    Science.gov (United States)

    Sydora, O L; Hart, R T; Eckert, N A; Martinez Baez, E; Clark, A E; Benmore, C J

    2018-04-03

    Structurally characterized chromium(iii) carboxylates form clusters with a variety of bridging groups introduced from aqueous reaction conditions. The first homoleptic monomeric chromium(iii) carboxylate has been prepared using an anhydrous salt metathesis synthetic route. The carboxylate groups coordinate the chromium in a bidentate chelate yielding an aliphatic soluble complex. The complex was characterized by a variety of methods including high energy X-ray diffraction, FD-MS, IR and Raman spectroscopy, complemented by DFT modeling.

  10. Skin permeation and cutaneous hypersensitivity as a basis for making risk assessments of chromium as a soil contaminant

    Energy Technology Data Exchange (ETDEWEB)

    Bagdon, R.E. (UMDNJ-Robert Wood Johnson Medical School, Piscataway, NJ (United States) Rutgers, The State Univ. of New Jersey, Piscataway (United States)); Hazen, R.E. (New Jersey Dept. of Environmental Protection, Trenton (United States))

    1991-05-01

    A literature review of experimental and human exposure studies of skin permeation and cutaneous hypersensitivity reactions evoked by chromium was carried out to provide a basis for making a risk assessment of chromium as a soil contaminant. In vitro and in vivo studies demonstrated that 1 to 4% of the applied dose of hexavalent and trivalent chromium to guinea pig skin penetrated skin within 5 to 24 hours after application. Ultrastructural investigations showed that hexavalent chromium localized intracellularly and extracellularly in the upper layers of guinea pig epidermis. The potential of hexavalent chromium to produce a skin sensitization reaction is readily demonstrated using animal models. The incidence and characteristics of chromium-induced skin hypersensitivity as a clinical entity are described. A health effects survey of populations exposed to chromium slag in soil in Tokyo, Japan extending over 8 years indicated a tendency toward symptoms characterized as headache, chromic fatigue, and gastrointestinal complaints, positive occult blood tests, minute hematuria and albuminuria suggestive of incipient renal disease, and a tendency toward an increase in contact dermatitis that was seasonally related. Based on these data, the cleanup level of total chromium in soil is designated as 75 mg/kg. It is proposed that levels of total chromium lower than 75 mg/kg in soil would avoid undue risk of contact dermatitis.

  11. Serum chromium concentrations in type 2 diabetic patients attending ...

    African Journals Online (AJOL)

    FPG). Lower serum chromium concentrations and poor chromium status are common in type 2 diabetics in Osogbo, Nigeria. Keywords: Diabetes, serum chromium, glucose tolerance, insulin. International Journal of Natural and Applied Sciences ...

  12. Intestinal absorption of chromium as affected by wheat bran

    International Nuclear Information System (INIS)

    Keim, K.S.; Holloway, C.L.; Hegsted, M.

    1986-01-01

    This study was designed to investigate the influence of dietary fiber, as found in wheat bran, on the absorption of chromium. Twenty male Sprague-Dawley rats were divided into two groups of 10. The control was fed a semi-purified diet containing casein, methionine, cornstarch, sucrose, corn oil, mineral and vitamin mix, and choline bitartrate. The experimental group was fed the same diet but with soft red winter wheat bran added to a level of 35% of the diet at the expense of sucrose. To determine chromium absorption and uptake by selected tissues, rats were fasted for 24 hr, fed 5 g of the respective diet, 2 hr later intubated with 100μCi of Cr-51of sacrificed 24 hr later. The rats wee housed in metabolic cages after the Cr-51 intubation. The addition of wheat brand to the diet did not significantly affect chromium absorption as measured by percent dose of Cr-51 in the 24 hr urine. The percent dose in the control group was 0.68 +/- 0.20% (mean +/- SEM) and in the experimental group 0.63 +/- 0.24% (mean +/-SEM) (N.S.). The cr-51 uptake of liver, spleen, jejunum, and blood was not statistically different between groups. These results indicate that dietary fiber as found in wheat bran does not impair intestinal absorption of chromium

  13. Molecular and biopharmaceutical investigation of alginate-inulin synbiotic coencapsulation of probiotic to target the colon.

    Science.gov (United States)

    Atia, Abdelbasset; Gomma, Ahmed I; Fliss, Ismail; Beyssac, Eric; Garrait, Ghislain; Subirade, Muriel

    2017-03-01

    Colon targeting, as a site-specific delivery for oral formulation, remains a major challenge, especially for sensitive bioactive components such as therapeutic forms of phages, live attenuated virus and prebiotics-probiotics association. Synbiotics could be used to protect encapsulated probiotics during the gastrointestinal tract and control their release in the colon. To achieve these goals, effective prebiotics, such as inulin, could be combined with alginate - the most exploited polymer used for probiotic encapsulation - in the form of beads. This work aimed to study the biopharmaceutical behaviour of alginate beads (A) and inulin-alginate beads of different inulin concentrations (5 or 20%) in 2% alginate (AI5, AI20). Beads were loaded with three probiotic strains (Pediococcus acidilactici Ul5, Lactobacillus reuteri and Lactobacillus salivarius). Dissolution of beads was studied by USP4 under conditions simulating the gastrointestinal condition. The survival rates of the bacterial strains were measured by a specific qPCR bacterial count. Mucoadhesiveness of beads was studied by an ex vivo method using intestinal mucosa. To understand the behaviour of each formulation, the ultrastructure of the polymeric network was studied using scanning electron microscopy (SEM). Molecular interactions between alginate and inulin were studied by Fourier transform infra-red spectroscopy (FTIR). Dissolution results suggested that the presence of inulin in beads provided more protection for the tested bacterial strains against the acidic pH. AI5 was the most effective formulation to deliver probiotics to the colon simulation conditions. FTIR and SEM investigations explained the differences in behaviour of each formula. The developed symbiotic form provided a promising matrix for the development of colonic controlled release systems.

  14. Electronic structure of chromium-doped lead telluride-based diluted magnetic semiconductors

    International Nuclear Information System (INIS)

    Skipetrov, E.P.; Pichugin, N.A.; Slyn'ko, E.I.; Slyn'ko, V.E.

    2011-01-01

    The crystal structure, composition, galvanomagnetic and oscillatory properties of the Pb 1-x-y Sn x Cr y Te (x = 0, 0.05-0.30, y ≤ 0.01) alloys have been investigated with varying matrix composition and chromium impurity concentration. It is shown that the chromium impurity atoms dissolve in the crystal lattice at least up to 1 mol.%. The following increase of the chromium concentration leads to the appearance of microscopic regions enriched with chromium and inclusions of Cr-Te compounds. A decrease of the hole concentration, a p-n-conversion of the conductivity type and a pinning of the Fermi level by the chromium resonant level are observed with increasing chromium content. Initial rates of changes in the free carrier concentration on doping are determined. The dependences of electron concentration and Fermi level on tin content are calculated by the two-band Kane dispersion relation. A diagram of electronic structure rearrangement for the chromium-doped alloys with varying the matrix composition is proposed.

  15. Comparison of Ultrasound-Assisted and Regular Leaching of Vanadium and Chromium from Roasted High Chromium Vanadium Slag

    Science.gov (United States)

    Wen, Jing; Jiang, Tao; Gao, Huiyang; Liu, Yajing; Zheng, Xiaole; Xue, Xiangxin

    2018-02-01

    Ultrasound-assisted leaching (UAL) was used for vanadium and chromium leaching from roasted material obtained by the calcification roasting of high-chromium-vanadium slag. UAL was compared with regular leaching. The effect of the leaching time and temperature, acid concentration, and liquid-solid ratio on the vanadium and chromium leaching behaviors was investigated. The UAL mechanism was determined from particle-size-distribution and microstructure analyses. UAL decreased the reaction time and leaching temperature significantly. Furthermore, 96.67% vanadium and less than 1% chromium were leached at 60°C for 60 min with 20% H2SO4 at a liquid-solid ratio of 8, which was higher than the maximum vanadium leaching rate of 90.89% obtained using regular leaching at 80°C for 120 min. Ultrasonic waves broke and dispersed the solid sample because of ultrasonic cavitation, which increased the contact area of the roasted sample and the leaching medium, the solid-liquid mass transfer, and the vanadium leaching rate.

  16. In vitro and in vivo investigations of targeted chemotherapy with magnetic nanoparticles

    International Nuclear Information System (INIS)

    Alexiou, Christoph; Jurgons, Roland; Schmid, Roswitha; Hilpert, Andrea; Bergemann, Christian; Parak, Fritz; Iro, Heinrich

    2005-01-01

    Magnetic drug targeting is a local drug delivery system. Electromicroscopic pictures document the ferrofluid enrichment in the intracellular space in vitro. In vivo experiments were performed in VX2 tumor-bearing rabbits using magnetic nanoparticles bound to mitoxantrone. High-pressure liquid chromatography (HPLC) analyses after magnetic drug targeting showed an increasing concentration of the chemotherapeutic agent in the tumor region compared to regular systemic chemotherapy

  17. Investigation of radiation characteristics of laser plasma on a surface of metal targets

    Science.gov (United States)

    Anikeev, Boris V.; Khaydukov, Evgeny V.; Khramov, Vladimir N.; Sevost'yanov, Andrey V.; Zatrudina, Rimma S.

    2007-06-01

    Results of numerical model operation of the x-ray radiation spectra and values of the magnetic field induction of the laser plasma received on aluminium and copper targets under action of USP are presented in this work. In calculations the mathematcial model including combined equations of ideal magnetohydrodynamics in vie of tranpsor ot laser radiation and a self-radiation of laser plasm, supplemented by equations of state and tabulared absorption constant was used. Calculations have shown the oscillation of the x-rays in a pectral rang 1-10 keV with intensity up to 10 11 W/cm2. It is revealed that the accoutn of a heating of plasma by the laser USP changes sharply the morphology of a powerful shock plams wave. Calucation has shown that near to a surface of a target there is an oscillation of spontaneous magnetic fields with an induction about 5•10 7 Gs. And medial value of a magnetic field induction on a copper target in 1. times is more than on an aluminium target. The electron concnetration in laser plams on a copper target, on the average, in 1.3 times is more than on an aluminium target. The velocity of a motion of front of laser plama is ovservationally estimaed at an optical breakdown in atmosphere which ahs made quantity about 7.5•10 6cm/s.

  18. Investigation of flow asymmetry and instability in the liquid mercury target of the Spallation Neutron Source

    International Nuclear Information System (INIS)

    Pointer, D.; Ruggles, A.; Wendel, M.; Crye, J.

    2000-01-01

    The Spallation Neutron Source (SNS) will utilize a liquid mercury target placed in the path of a high-energy proton beam to produce neutrons for research activities. As the high-energy protons interact with the mercury target, the majority of the beam energy is converted to thermal energy. The liquid mercury must provide sufficient heat transfer to maintain the temperature of the target structure within the thermal limits of the structural materials. Therefore, the behavior of the liquid mercury flow must be characterized in sufficient detail to ensure accurate evaluation of heat transfer in the mercury target. A combination of experimental and computational methods is utilized to characterize the flow in these preliminary analyses. Preliminary studies of the liquid mercury flow in the SNS target indicate that the flow in the exit channel may exhibit multiple recirculation zones, flow asymmetries, and possibly large-scale flow instabilities. While these studies are not conclusive, they serve to focus the efforts of subsequent CFD modeling and experimental programs to better characterize the flow patterns in the SNS mercury target

  19. Development of ductile high-strength chromium alloys, phase 2

    Science.gov (United States)

    Filippi, A. M.

    1973-01-01

    Strength and ductility were evaluated for chromium alloys dispersion hardened with the putative TaC, TaB, CbC, and CbB compounds. TaC and TaB proved to be the most potent strengtheners, but when combined, their effect far outweighed that produced individually. Tests at 1422 K (2100 F) on an alloy containing these two compounds at the combined level of 0.5 m/o revealed a 495 MN/sq m (70 ksi) tensile strength for wrought material, and a 100 hour rupture strength of 208 MN/sq m (30 ksi) when solution annealed and aged to maximize creep resistance. These levels of high temperature strength greatly exceed that reported for any other chromium-base alloy. The ductile-to-brittle transition temperature (DBTT) of the two phase strengthened alloy occurred at approximately 588 K (600 F) when heat treated to optimize creep strength and was not improved by fabrication to produce a wrought and recovered microstructure. The lowest DBTT measured on any of the alloys investigated was 422 K (300 F). Strengthening phases actually formed in Cr-Ta-B and Cr-Cb-B compositions are probable M2CrB2 (M=Ta or Cb) compounds of tetragonal crystal structure. The likely habit relationship between these compounds and chromium is postulated. Cube habit coherency was identified for TaC precipitation in chromium by electron microscopy. In another study, the maximum solubility of carbon in chromium was indicated to lie between 3/4 and 1 a/o and that of boron to be 1/2 a/o.

  20. The influence of solidification speed during heating on allotropic transformations of chromium cast iron casting

    Directory of Open Access Journals (Sweden)

    M. Przybył

    2008-08-01

    Full Text Available The unique stand to founding dilatometric samples ("on ready” which solidify with different cooling speeds was presented. The dilatometric investigations, X-ray, metallographic they disclosed the occurrence in matrix of chromium cast iron of considerable quantity of austenite in dependence from concentration of chromium (18% and 23% and the speed of solidification. Castings these despite large part of austenite mark with high hardness in raw state.

  1. Chromium in aqueous nitrate plutonium process streams: Corrosion of 316 stainless steel and chromium speciation

    International Nuclear Information System (INIS)

    Smith, W.H.; Purdy, G.M.

    1995-01-01

    This study was undertaken to determine if chromium(+6) could exist in plutonium process solutions under normal operating conditions. Four individual reactions were studied: the rate of dissolution of stainless steel, which is the principal source of chromium in process solutions; the rate of oxidation of chromium(+3) to chromium(+6) by nitric acid; and the reduction of chromium(+6) back to chromium(+3) by reaction with stainless steel and with oxalic acid. The stainless steel corrosion rate was found to increase with increasing nitric acid concentration, increasing hydrofluoric acid concentration, and increasing temperature. Oxidation of chromium(+3) to chromium(+6) was negligible at room temperature and only became significant in hot concentrated nitric acid. The rate of reduction of chromium(+6) back to chromium(+3) by reaction with stainless steel or oxalic acid was found to be much greater than the rate of the reverse oxidation reaction. Based on these findings and taking into account normal operating conditions, it was determined that although there would be considerable chromium in plutonium process streams it would rarely be found in the (+6) oxidation state and would not exist in the (+6) state in the final process waste solutions

  2. Chromium in aqueous nitrate plutonium process streams: Corrosion of 316 stainless steel and chromium speciation

    International Nuclear Information System (INIS)

    Smith, W.H.; Purdy, G.

    1995-01-01

    This study was undertaken to determine if chromium +6 could exist in plutonium process solutions under normal operating conditions. Four individual reactions were studied: the rate of dissolution of stainless steel, which is the principal source of chromium in process solutions; the rate of oxidation of chromium +3 to chromium +6 by nitric. acid; and the reduction of chromium +6 back to chromium +3 by reaction with stainless steel and with oxalic acid. The stainless steel corrosion rate was found to increase with increasing nitric acid concentration, increasing hydrofluoric acid concentration, and increasing temperature. Oxidation of chromium +3 to chromium +6 was negligible at room temperature and only became significant in hot concentrated nitric acid. The rate of reduction of chromium +6 back to chromium +3 by reaction with stainless steel or oxalic acid was found to be much greater than the rate of the reverse oxidation reaction. Based on these findings and taking into account normal operating conditions, it was determined that although there would be considerable chromium in plutonium process streams it would rarely be found in the +6 oxidation state and would not exist in the +6 state in the final process waste solutions

  3. Maternal chromium restriction modulates miRNA profiles related to lipid metabolism disorder in mice offspring.

    Science.gov (United States)

    Zhang, Qian; Xiao, Xinhua; Zheng, Jia; Li, Ming; Yu, Miao; Ping, Fan; Wang, Zhixin; Qi, Cuijuan; Wang, Tong; Wang, Xiaojing

    2017-08-01

    Increasing evidence shows that maternal nutrition status has a vital effect on offspring susceptibility to obesity. MicroRNAs are related to lipid metabolism processes. This study aimed to evaluate whether maternal chromium restriction could affect miRNA expression involved in lipid metabolism in offspring. Weaning C57BL/6J mice born from mothers fed with normal control diet or chromium-restricted diet were fed for 13 weeks. The adipose miRNA expression profile was analyzed by miRNA array analysis. At 16 weeks old, pups from dams fed with chromium-restricted diet exhibit higher body weight, fat weight, and serum TC, TG levels. Six miRNAs were identified as upregulated in the RC group compared with the CC group, whereas eight miRNAs were lower than the threshold level set in the RC group. In the validated target genes of these differentially expressed miRNA, the MAPK signaling pathway serves an important role in the influence of early life chromium-restricted diet on lipid metabolism through miRNA. Long-term programming on various specific miRNA and MAPK signaling pathway may be involved in maternal chromium restriction in the adipose of female offspring. Impact statement For the first time, our study demonstrates important miRNA differences in the effect of maternal chromium restriction in offspring. These miRNAs may serve as "bridges" between the mother and the offspring by affecting the MAPK pathway.

  4. Effect of recasting on the thickness of metal-ceramic interface of nickel-chromium and cobalt-chromium alloys

    Directory of Open Access Journals (Sweden)

    Mirković Nemanja

    2008-01-01

    Full Text Available Introduction/Aim. This research was done to establish recasting effects of nickel-chromium and cobalt-chromium alloys on the thickness of their metal-ceramic interface in making fixed partial dentures. Metal-ceramic interface determines their functional integrity and prevents damages on ceramics during mastication. Investigation of metal-ceramic samples is supposed to show if base metal alloys for metalceramics are successfully recycled without any risk of reduction of metal-ceramic interface thickness. Methods. The research was performed as an experimental study. Per six metal-ceramic samples of nickel-chromium alloy (Wiron99 and cobalt-chromium alloy (Wirobond C were made each. Alloy residues were recycled through twelve casting generations with the addition of 50% of new alloy on the occasion of every recasting. Analysis Energy Dispersive X-ray (EDX (Oxford Instruments and Scanning Electon Microscop (SEM analysis (JEOL were used to determine thickness of metal-ceramic interface together with PC Software for quantification of visual information's (KVI POPOVAC. Results. Results of this research introduced significant differences between thickness of metal-ceramic interface in every examined recycle generation. Recasting had negative effect on thickness of metal-ceramic interface of the examined alloys. This research showed almost linear reduction of elastic modulus up to the 12th generation of recycling. Conclusion. Recasting of nickel-chromium and cobaltchromium alloys is not recommended because of reduced thickness of metal-ceramic interface of these alloys. Instead of recycling, the alloy residues should be returned to the manufacturers.

  5. Preliminary investigations for technology assessment of 99Mo production from LEU [low enriched uranium] targets

    International Nuclear Information System (INIS)

    Vandegrift, G.F.; Chaiko, D.J.; Heinrich, R.R.; Kucera, E.T.; Jensen, K.J.; Poa, D.S.; Varma, R.; Vissers, D.R.

    1986-11-01

    This paper presents the results of preliminary studies on the effects of substituting low enriched uranium (LEU) for highly enriched uranium (HEU) in targets for the production of fission product 99 Mo. Issues that were addressed are: (1) purity and yield of the 99 Mo//sup 99m/Tc product, (2) fabrication of LEU targets and related concerns, and (3) radioactive waste. Laboratory experimentation was part of the efforts for issues (1) and (2); thus far, radioactive waste disposal has only been addressed in a paper study. Although the reported results are still preliminary, there is reason to be optimistic about the feasibility of utilizing LEU targets for 99 Mo production. 37 refs., 1 fig., 5 tabs

  6. Utilization of alum sludge as chromium removal

    Science.gov (United States)

    Zahari, Nazirul Mubin; Sidek, Lariyah Mohd; Zulkifli, Muhammad Azmeer Asyraf; Hua, Chua Kok; Jalil, Nurulhidayah Abdul

    2017-09-01

    The amount of alum sludge produced at water treatment plant has become a problem where it is highly costly in order to dispose them. Various research was conducted to find the most suitable and economic alternative to recycle and reused of alum sludge. In this study, alum sludge was retrieved from Waterworks where it was dewatered, dried, grounded and sieved to obtain smallest particle sizes of alum sludge. The synthetic water was prepared at the laboratory in as it was used to imitate the properties of real water contaminated with chromium. This study was conducted to determine the percentage reduction of chromium concentration in synthetic water by using alum sludge as absorbent. The percentage reduction of chromium was observed under the effect of initial concentration of chromium and the height of alum sludge. The result indicates that chromium concentration reduction was the highest at the lowest initial concentration and at the highest height of alum sludge and vice versa.

  7. Adsorption of chromium(VI) on pomace-An olive oil industry waste: Batch and column studies

    International Nuclear Information System (INIS)

    Malkoc, Emine; Nuhoglu, Yasar; Dundar, Murat

    2006-01-01

    The waste pomace of olive oil factory (WPOOF) was tested for its ability to remove chromium(VI) from aqueous solution by batch and column experiments. Various thermodynamic parameters, such as ΔG o , ΔH o and ΔS o have been calculated. The thermodynamics of chromium(VI) ion onto WPOOF system indicates spontaneous and endothermic nature of the process. The ability of WPOOF to adsorb chromium(VI) in a fixed bed column was investigated, as well. The effect of operating parameters such as flow rate and inlet metal ion concentration on the sorption characteristics of WPOOF was investigated. The longest breakthrough time and maximum of Cr(VI) adsorption is obtained at pH 2.0. The total adsorbed quantities, equilibrium uptakes and total removal percents of chromium(VI) related to the effluent volumes were determined by evaluating the breakthrough curves obtained at different flow rates and different inlet chromium(VI) concentrations for adsorbent. The data confirmed that the total amount of sorbed chromium(VI) and equilibrium chromium(VI) uptake decreased with increasing flow rate and increased with increasing inlet chromium(VI) concentration. The Adams-Bohart model were used to analyze the experimental data and the model parameters were evaluated

  8. Initial investigations of (np)-scattering with a polarized deuterium target at ANKE-COSY

    Energy Technology Data Exchange (ETDEWEB)

    Gou, Boxing

    2015-07-01

    The understanding of the forces among nucleons is fundamental to the whole of nuclear and hadronic physics. The nucleon-nucleon (NN) scattering is the ideal probe to study the nuclear forces. The scattering amplitudes for the complete description of the NN interactions can be reconstructed from phase-shift analyses (PSA), which requires measurements with polarized experiments. The existing data allow to extract unambiguous proton-proton (pp) amplitudes below 2 GeV. However, there is very little known about the neutron-proton (np) system above 800 MeV nucleon energy. THE ANKE-COSY collaboration has embarked on a systematic program which aims to extract the np scattering amplitudes through the deuteron-proton charge-exchange process dp→{pp}{sub s}n. First part of the program via polarized deuteron beam and hydrogen target allowed successful measurement of np amplitudes up to 1.135 GeV nucleon energy, which is the maximum nucleon energy that can be accessed with deuteron beam at COSY. Via inverse kinematics, i.e. using a proton beam incident on a polarized deuterium target will allow to enhance the np study up to 2.8 GeV, the highest energy available at COSY. The method of inverse kinematics has to be validated prior to the production experiment. As the proof-of-principle (POP) experiment, the initial research has been conducted at proton energy T{sub p}=600 MeV using a polarized deuterium target. The projectiles were measured by two silicon tracking telescopes (STT) placed closed to the target and by the ANKE sub-detection systems. Four polarization modes of the deuterium target were employed. In order to increase the effective target thickness, polarized deuterium atoms produced by the atomic beam source (ABS) was filled into a storage cell, where the circulating COSY beam collides with the target. The target polarizations were measured using the proton-deuteron elastic reaction. The vector and tensor analyzing powers A{sub y} and A{sub yy} of pvector d

  9. Molecular investigations of protriptyline as a multi-target directed ligand in Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Sneha B Bansode

    Full Text Available Alzheimer's disease (AD is a complex neurodegenerative disorder involving multiple cellular and molecular processes. The discovery of drug molecules capable of targeting multiple factors involved in AD pathogenesis would greatly facilitate in improving therapeutic strategies. The repositioning of existing non-toxic drugs could dramatically reduce the time and costs involved in developmental and clinical trial stages. In this study, preliminary screening of 140 FDA approved nervous system drugs by docking suggested the viability of the tricyclic group of antidepressants against three major AD targets, viz. Acetylcholinesterase (AChE, β-secretase (BACE-1, and amyloid β (Aβ aggregation, with one member, protriptyline, showing highest inhibitory activity. Detailed biophysical assays, together with isothermal calorimetry, fluorescence quenching experiments, kinetic studies and atomic force microscopy established the strong inhibitory activity of protriptyline against all three major targets. The molecular basis of inhibition was supported with comprehensive molecular dynamics simulations. Further, the drug inhibited glycation induced amyloid aggregation, another important causal factor in AD progression. This study has led to the discovery of protriptyline as a potent multi target directed ligand and established its viability as a promising candidate for AD treatment.

  10. New investigations of organic compounds for targets with polarized hydrogen nuclei

    Science.gov (United States)

    Bunyatova, E. I.

    1995-02-01

    Pentanol C 5H 12O, polyethylene (CH 2) n and their deuterated analogues C 5D 12O and (CD 2) n are proposed as target materials. Particular attention is paid to the production of materials in a glass-like (amorphous) state.

  11. New investigations of organic compounds for targets with polarized hydrogen nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Bunyatova, E.I. [Joint Inst. for Nuclear Research, Dubna (Russian Federation)

    1995-03-01

    Pentanol C{sub 5}H{sub 12}O, polyethylene (CH{sub 2}){sub n} and their deuterated analogues C{sub 5}D{sub 12}O and (CD{sub 2}){sub n} are proposed as target materials. Particular attention is paid to the production of materials in a glass-like (amorphous) state. ((orig.))

  12. Investigation of hopped frequency waveforms for range and velocity measurements of radar targets

    CSIR Research Space (South Africa)

    Kathree, U

    2015-10-01

    Full Text Available In the field of radar, High Range Resolution (HRR) profiles are often used to improve target tracking accuracy in range and to allow the radar system to produce an image of an object using techniques such as inverse synthetic aperture radar (ISAR...

  13. Investigations on the necessity of dose calculations for several planes of the target volume

    International Nuclear Information System (INIS)

    Richter, E.

    1987-01-01

    In radiotherapy planning, the shape of a target volume can at present be exactly delimited by means of computed tomography. A method often applied is to project the largest target volume scan on the plane of the central ray and to calculate the dose in this plane. This method does not allow to take into account any change of the target volume scan which will be mainly due to the body contours of the patient. The results of dose calculations made in several planes for pharyngeal and laryngeal tumors are presented. With this procedure, 33 out of 60 irradiation techniques for nine tumor sites meet the requirements with regard to the central ray plane. If several planes are regarded, this is only true for ten irradiation plans. If is therefore absolutely necessary to calculate the doses of several planes if the target volume has an irregular shape or if the body contours vary considerably. This is the only way to prevent a false treatment caused by possibly severe dose excesses or dose insufficiencies in radiotherapy. (orig.) [de

  14. On-Demand Targeting: Investigating Biology with Proximity-Directed Chemistry.

    Science.gov (United States)

    Long, Marcus J C; Poganik, Jesse R; Aye, Yimon

    2016-03-23

    Proximity enhancement is a central chemical tenet underpinning an exciting suite of small-molecule toolsets that have allowed us to unravel many biological complexities. The leitmotif of this opus is "tethering"-a strategy in which a multifunctional small molecule serves as a template to bring proteins/biomolecules together. Scaffolding approaches have been powerfully applied to control diverse biological outcomes such as protein-protein association, protein stability, activity, and improve imaging capabilities. A new twist on this strategy has recently appeared, in which the small-molecule probe is engineered to unleash controlled amounts of reactive chemical signals within the microenvironment of a target protein. Modification of a specific target elicits a precisely timed and spatially controlled gain-of-function (or dominant loss-of-function) signaling response. Presented herein is a unique personal outlook conceptualizing the powerful proximity-enhanced chemical biology toolsets into two paradigms: "multifunctional scaffolding" versus "on-demand targeting". By addressing the latest advances and challenges in the established yet constantly evolving multifunctional scaffolding strategies as well as in the emerging on-demand precision targeting (and related) systems, this Perspective is aimed at choosing when it is best to employ each of the two strategies, with an emphasis toward further promoting novel applications and discoveries stemming from these innovative chemical biology platforms.

  15. Perceived-Target-Language-Use Survey in the English Classrooms in China: Investigation of Classroom-Related and Institutional Factors

    Science.gov (United States)

    Yan, Edith M. Y.; Fung, Irene Y. Y.; Liu, Lili; Huang, Xiaoyan

    2016-01-01

    This quantitative study investigated the extent and contexts of target language (TL) use in English language classrooms. Participants were 2,906 students from seven secondary schools and four universities in the more developed cities in southern China. They were put into five groups according to their educational stage and whether their content…

  16. Chemical bonding of nitrogen in low-energy implanted chromium

    International Nuclear Information System (INIS)

    Palacio, C.; Arranz, A.; Diaz, D.

    2006-01-01

    Chromium nitride films have been grown by nitrogen implantation of metallic chromium at room temperature in the energy range of 0.25-5 keV varying the ion dose, the ion beam energy and the angle between the ion beam and the normal to the surface. X-ray photoelectron spectroscopy (XPS) and Factor Analysis (FA) have been used to characterize in situ the chemical composition of the films. The number and spectral shape of the different Cr-N phases formed during nitrogen implantation, as well as their concentrations, have been obtained by means of FA, involving principal component analysis and target testing transformation, of the Cr 2p and N 1s XPS bands. FA results show that the composition of the chromium nitride films depends on the ion dose, on the ion energy and on the angle between the ion beam and the normal to the surface. For all ion beam energies two chromium nitride phases are formed, that is, Cr 2 N and CrN, however, for ion beam energies ≤ 0.5 k eV and normal incidence, the films are only composed of CrN, that is, the phase with the highest nitrogen content. For those experimental conditions, comparison of the experimental nitrogen concentration obtained by FA with that obtained from TRIDYN simulations suggests that in addition to nitrogen implantation and atomic mixing, other mechanisms like ion beam enhanced diffusion or the chemical reactivity of the Cr substrate towards nitrogen should be taken into account at low ion energies

  17. Investigations of astrophysically interesting nuclear reactions by the use of gas target techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hammer, J.W. [Inst. fuer Strahlenphysik, Univ. Stuttgart, Stuttgart (Germany)

    1998-06-01

    A brief review of the common properties of windowless and recirculating gas targets is presented. As example the Stuttgart gas target facility Rhinoceros in the extended and in the supersonic jet mode with its properties and techniques is explained, also with respect to gas purification techniques. Furthermore several typical experiments from the field of nuclear astrophysics with characteristic results are described (D({alpha},{gamma}){sup 6}Li, {sup 15}N({alpha},{gamma}){sup 19}F, {sup 16}O(p,{gamma}){sup 17}F, {sup 16}O({alpha},{gamma}){sup 20}Ne, {sup 20}Ne({alpha},{gamma}){sup 24}Mg, {sup 21}Ne({alpha},n){sup 24}Mg, {sup 18}O({alpha},n){sup 21}Ne, {sup 17}O({alpha},n){sup 20}Ne). In several cases the experimental sensitivity could be raised by up to a factor of 10{sup 6}. (orig.)

  18. Low-chromium reduced-activation chromium-tungsten steels

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L.; Alexander, D.J.; Maziasz, P.J. [Oak Ridge National Lab., TN (United States)

    1996-10-01

    Bainitic microstructures formed during continuous cooling can differ from classical upper and lower bainite formed during isothermal transformation. Two types of non-classical bainite were observed depending on the cooling rate: carbide-free acicular bainite at rapid cooling rates and granular bainite at slower cooling rates. The Charpy impact toughness of the acicular ferrite was found to be considerably better than for the granular bainite. It was postulated that alloying to improve the hardenability of the steel would promote the formation of acicular bainite, just as increasing the cooling rate does. To test this, chromium and tungsten were added to the 2 1/4Cr-2W and 2 1/4Cr-2WV steel compositions to increase their hardenability, and the microstructures and mechanical properties were examined.

  19. Optimization of chromium and tannic acid bioremediation by Aspergillus niveus using Plackett-Burman design and response surface methodology.

    Science.gov (United States)

    Chaudhary, Prachi; Chhokar, Vinod; Choudhary, Pragati; Kumar, Anil; Beniwal, Vikas

    2017-11-14

    A chromium and tannic acid resistance fungal strain was isolated from tannery effluent, and identified as Aspergillus niveus MCC 1318 based on its rDNA gene sequence. The MIC (minimum inhibitory concentration) of the isolate against chromium and tannic acid was found to be 200 ppm and 5% respectively. Optimization of physiochemical parameters for biosorption of chromium and tannic acid degradation was carried out by Plackett-Burman design followed by response surface methodology (RSM). The maximum chromium removal and tannic acid degradation was found to be 92 and 68% respectively by A. niveus. Chromium removal and tannic acid degradation was increased up to 11 and 6% respectively after optimization. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) was used to investigate biosorption phenomena.

  20. Investigation of potential targets of Porphyromonas CRISPRs among the genomes of Porphyromonas species.

    Science.gov (United States)

    Watanabe, Takayasu; Shibasaki, Masaki; Maruyama, Fumito; Sekizaki, Tsutomu; Nakagawa, Ichiro

    2017-01-01

    The oral bacterial species Porphyromonas gingivalis, a periodontal pathogen, has plastic genomes that may be driven by homologous recombination with exogenous deoxyribonucleic acid (DNA) that is incorporated by natural transformation and conjugation. However, bacteriophages and plasmids, both of which are main resources of exogenous DNA, do not exist in the known P. gingivalis genomes. This could be associated with an adaptive immunity system conferred by clustered regularly interspaced short palindromic repeat (CRISPR) and CRISPR-associated (cas) genes in P. gingivalis as well as innate immune systems such as a restriction-modification system. In a previous study, few immune targets were predicted for P. gingivalis CRISPR/Cas. In this paper, we analyzed 51 P. gingivalis genomes, which were newly sequenced, and publicly available genomes of 13 P. gingivalis and 46 other Porphyromonas species. We detected 6 CRISPR/Cas types (classified by sequence similarity of repeat) in P. gingivalis and 12 other types in the remaining species. The Porphyromonas CRISPR spacers with potential targets in the genus Porphyromonas were approximately 23 times more abundant than those with potential targets in other genus taxa (1,720/6,896 spacers vs. 74/6,896 spacers). Porphyromonas CRISPR/Cas may be involved in genome plasticity by exhibiting selective interference against intra- and interspecies nucleic acids.

  1. [Experimental investigation of laser plasma soft X-ray source with gas target].

    Science.gov (United States)

    Ni, Qi-liang; Gong, Yan; Lin, Jing-quan; Chen, Bo; Cao, Jian-lin

    2003-02-01

    This paper describes a debris-free laser plasma soft X-ray source with a gas target, which has high operating frequency and can produce strong soft X-ray radiation. The valve of this light source is drived by a piezoelectrical ceramic whose operating frequency is up to 400 Hz. In comparison with laser plasma soft X-ray sources using metal target, the light source is debris-free. And it has higher operating frequency than gas target soft X-ray sources whose nozzle is controlled by a solenoid valve. A channel electron multiplier (CEM) operating in analog mode is used to detect the soft X-ray generated by the laser plasma source, and the CEM's output is fed to to a charge-sensitive preamplifier for further amplification purpose. Output charges from the CEM are proportional to the amplitude of the preamplifier's output voltage. Spectra of CO2, Xe and Kr at 8-14 nm wavelength which can be used for soft X-ray projection lithography are measured. The spectrum for CO2 consists of separate spectral lines originate mainly from the transitions in Li-like and Be-like ions. The Xe spectrum originating mainly from 4d-5f, 4d-4f, 4d-6p and 4d-5p transitions in multiply charged xenon ions. The spectrum for Kr consists of separate spectral lines and continuous broad spectra originating mainly from the transitions in Cu-, Ni-, Co- and Fe-like ions.

  2. QbD approach to investigate product and process variabilities for brain targeting liposomes.

    Science.gov (United States)

    Kamal, Nahid; Cutie, Anthony J; Habib, Muhammad J; Zidan, Ahmed S

    2014-10-13

    Abstract Efficacy of central nervous system-acting medications is limited by its localization and ability to cross the blood-brain barrier (BBB); therefore, the crux is in designing delivery systems targeted to cross the BBB. Toward this objective, this study proposed pegylated and glycosylated citalopram hydrobromide (Cit-HBr) liposomes as a delivery approach for brain targeting. The multicomponent liposomes were evaluated for drug encapsulation, vesicular size, size distribution, conductivity and drug release characteristics. Moreover, the interaction among the employed components was evaluated by Fourier transform infrared, differential scanning calorimetric and X-ray diffraction analysis. Through a systematic screening design of formulation and process variables in the optimization phase, an improvement of Cit-HBr loading, fine vesicular size with narrow size distribution, greater stability and sustained release features were achieved. The compatibility studies unveiled a significant interaction between Cit-HBr and dicetyl phosphate to control drug encapsulation and release properties. The optimization process showed a minimal range of design space to achieve the preset desirability; more precisely dicetyl phosphate, polyethylene glycol, N-acetyl glucosamine and freeze-thaw cycles of 3%, 5%, 4% and 2 cycles, respectively, were used. Using brain endothelial cell models, the optimized formulations showed an acceptable cell viability with preserved monolayer integrity and an enhanced flux and permeability. Thus, this study has proposed an optimized pegylated and glycosylated vector that is a promising step for brain targeting.

  3. Experimental patch testing with chromium-coated materials

    DEFF Research Database (Denmark)

    Bregnbak, David; Thyssen, Jacob P; Jellesen, Morten Stendahl

    2017-01-01

    Chromium coatings on metal alloys can be decorative, and prevent corrosion and metal ion release. We recently showed that handling of a chromium-containing disc resulted in chromium deposition on the skin. To examine patch test reactivity to chromium-coated discs. We included 15 patients: 10...

  4. Evaluation of chromium speciation and transport characteristics in the Hanford Site 100D and 100H areas

    International Nuclear Information System (INIS)

    Thornton, E.C.; Amonette, J.E.; Olivier, J.

    1995-08-01

    Field and laboratory investigations have been conducted to define the fate and transport characteristics of chromium contamination present in the 100D/H Areas of the Hanford Site. This information is relevant to assessing the impact of the release of hexavalent chromium to the Columbia River. Included in this study was the determination of the concentration and aqueous speciation of chromium in the unconfined acquifer and an assessment of potential changes in speciation as groundwater passes through the river/acquifer transition zone and mixes with the Columbia River. The results of this study indicate that chromium present within the Hanford acquifer is predominantly in the oxidized hexavalent state. Chromium is apparently stable in the oxidized form owing to its lack of organic matter within the acquifer. A portion of the chromium is removed as groundwater passes through the transition zone due to reduction and precipitation associated with sediment/water interaction processes. Chemical data collected from seep water samples, however, suggests, that most of the hexavalent chromium ultimately discharges into the Columbia River. Dilution of hexavalent chromium subsequently occurs during the mixing of groundwater and river water, with relatively little change taking place in speciation

  5. Investigations of effect of target thickness and detector collimation on 662 keV multiply backscattered gamma photons

    International Nuclear Information System (INIS)

    Sabharwal, Arvind D.; Sandhu, B.S.; Singh, Bhajan

    2009-01-01

    The present studies aimed to investigate the effects of detector collimation and target thickness on multiply backscattered gamma photons. The numbers of multiply backscattered events, having energy the same as in singly scattered distribution, are found to be increasing with target thickness, and saturate for a particular thickness known as saturation thickness. The saturation thickness is not altered by the variation in the collimator opening. The number and energy albedos, characterizing the reflection probability of a material, are also evaluated. Monte Carlo calculations support the present experimental work.

  6. Adsorption of chromium onto activated alumina: kinetics and thermodynamics studies.

    Science.gov (United States)

    Marzouk, Ikhlass; Dammak, Lassaad; Hamrouni, Béchir

    2013-02-01

    In this study, the removal of chromium (VI) by adsorption on activated alumina was investigated and the results were fitted to Langmuir, Freundlich, Dubinin-Redushkevich, and Temkin adsorption models at various temperatures. The constants of each model were evaluated depending on temperature. Thermodynamic parameters for the adsorption system were determined at 10, 25 and 40 degrees C. (deltaH degrees = -21.18 kJ x mol(-1); deltaG degrees = -8.75 to -7.43 kJ x mol(-1) and deltaS degrees = -0.043 kJ x K(-1) x mol(-1)). The obtained values showed that chromium (VI) adsorption is a spontaneous and exothermic process. The kinetic process was evaluated by first-order, second-order and Elovich kinetic models.

  7. Chromium in leather footwear-risk assessment of chromium allergy and dermatitis

    DEFF Research Database (Denmark)

    Thyssen, Jacob P; Strandesen, Maria; Poulsen, Pia B

    2012-01-01

    Background. Chromium-tanned leather footwear, which releases >3 ppm hexavalent Cr(VI), may pose a risk of sensitizing and eliciting allergic dermatitis. Objectives. To determine the content and potential release of chromium in leather footwear and to discuss the prevention of chromium contact...... allergy and dermatitis. Methods. Sixty pairs of leather shoes, sandals and boots (20 children's, 20 men's, and 20 women's) were purchased in Copenhagen and examined with X-ray fluorescence spectroscopy. Chromium was extracted according to the International Standard, ISO 17075. The detection level for Cr......(VI) was 3 ppm. Results. Chromium was identified in 95% of leather footwear products, the median content being 1.7% (range 0-3.3%). No association with store category or footwear category was found. A tendency for there to be a higher chromium content in footwear with high prices was shown (p(trend) = 0...

  8. Characteristics of chromium-allergic dermatitis patients prior to regulatory intervention for chromium in leather

    DEFF Research Database (Denmark)

    Bregnbak, David; Thyssen, Jacob P; Zachariae, Claus

    2014-01-01

    BACKGROUND: Chromium-tanned leather articles currently constitute the most important cause of contact allergy to chromium in Denmark. A regulation on the content of hexavalent chromium in leather was adopted in November 2013 by the EU member states. OBJECTIVES: To characterize patients...... with chromium allergy and their disease, to serve as a baseline for future studies on the potential effect of the new regulation on chromium in leather. METHODS: A questionnaire case-control study was performed on 155 dermatitis patients with positive patch test reactions to potassium dichromate and a matched...... control group of 621 dermatitis patients. Comparisons were made by use of a χ(2) -test and the Mann-Whitney U-test. Logistic regression analyses were used to test for associations. RESULTS: Sixty-six per cent of chromium-allergic patients had a positive history of contact dermatitis caused by leather...

  9. Leaching of chromium from chromium contaminated soil: Speciation study and geochemical modeling

    Directory of Open Access Journals (Sweden)

    Anđelković Darko H.

    2012-01-01

    Full Text Available Distribution of chromium between soil and leachate was monitored. A natural process of percolating rainwater through the soil was simulated in the laboratory conditions and studied with column leaching extraction. Migration of chromium in the soil is conditioned by the level of chromium soil contamination, the soil organic matter content, and rainwater acidity. Chromium (III and chromium(VI were determined by spectrophotometric method with diphenilcarbazide in acidic media. Comparing the results of chromium speciation in leachate obtained by experimental model systems and geochemical modelling calculations using Visual MINTEQ model, a correlation was observed regarding the influence of the tested parameters. Leachate solutions showed that the concentration of Cr depended on the organic matter content. The influence of pH and soil organic matter content is in compliance after its definition through experimental and theoretical way. The computer model - Stockholm Humic Model used to evaluate the leaching results corresponded rather well with the measured values.

  10. Experimental and theoretical investigations of crates information in an aluminium target in a PALS experiment

    Czech Academy of Sciences Publication Activity Database

    Borodziuk, S.; Doskach, I. Y.; Gus'kov, S.; Jungwirth, Karel; Kasperczuk, A.; Králiková, Božena; Krouský, Eduard; Limpouch, Jiří; Mašek, Karel; Pfeifer, Miroslav; Pisarczyk, P.; Pisarczyk, T.; Rohlena, Karel; Rozanov, V.; Skála, Jiří; Ullschmied, Jiří; Kálal, M.

    2004-01-01

    Roč. 49, č. 1 (2004), s. 7-14 ISSN 0029-5922 R&D Projects: GA MŠk LN00A100 Grant - others:HPRI-CT(XX) 1999-00053 Institutional research plan: CEZ:AV0Z2043910; CEZ:AV0Z1010921 Source of funding: R - rámcový projekt EK Keywords : laser -produced plasma * laser s targets * aluminium Subject RIV: BH - Optics, Masers, Laser s Impact factor: 0.167, year: 2004

  11. High-carbon chromium steel resistance to small plastic deformation

    International Nuclear Information System (INIS)

    Gajduchenya, V.F.; Madyanov, S.A.; Apaev, B.A.; Kirillov, Yu.V.; Sokolov, L.D.

    1978-01-01

    The phase composition of a steel with 1.08% C and 2.1% Cr, and the variation in the level of microstresses in the matrix as related to the annealing temperature in the range of 400-600 deg C and in the applied compression stress were investigated. To study the phase composition, and chromium content in the α-solution and the carbide phases, magnetic, chemical, and X-ray spectrum analyses were carried out. The change in the level of microstresses was determined roentgenographically. During the stress relaxation test at temperatures of 20-180 deg C, the mechanism of plastic deformation near the yield point was investigated. It is shown that three dislocation mechanisms operate in high-carbon chromium steel under the conditions at hand: overcoming the Pierls-Nabarro barriers by the dislocations, overcoming the stress fields of coherent carbide particles by dislocations, and circumvention of second-phase particles by dislocations. The dependence of the realization of the different plastic deformation mechanisms on the number of carbide particles and the chromium concentration in the matrix was established. The thermally activated nature of the motion of the dislocations under conditions of stress relaxation at an elevated temperature is noted

  12. Chromium in Drinking Water: Association with Biomarkers of Exposure and Effect

    Directory of Open Access Journals (Sweden)

    Eleni Sazakli

    2014-09-01

    Full Text Available An epidemiological cross-sectional study was conducted in Greece to investigate health outcomes associated with long-term exposure to chromium via drinking water. The study population consisted of 304 participants. Socio-demographics, lifestyle, drinking water intake, dietary habits, occupational and medical history data were recorded through a personal interview. Physical examination and a motor test were carried out on the individuals. Total chromium concentrations were measured in blood and hair of the study subjects. Hematological, biochemical and inflammatory parameters were determined in blood. Chromium in drinking water ranged from <0.5 to 90 μg·L−1 in all samples but one (220 μg·L−1, with a median concentration of 21.2 μg·L−1. Chromium levels in blood (median 0.32 μg·L−1, range <0.18–0.92 μg·L−1 and hair (median 0.22 μg·g−1, range 0.03–1.26 μg·g−1 were found within “normal range” according to the literature. Personal lifetime chromium exposure dose via drinking water, calculated from the results of the water analyses and the questionnaire data, showed associations with blood and hair chromium levels and certain hematological and biochemical parameters. Groups of subjects whose hematological or biochemical parameters were outside the normal range were not correlated with chromium exposure dose, except for groups of subjects with high triglycerides or low sodium. Motor impairment score was not associated with exposure to chromium.

  13. Simultaneous determination of chromium(III) and chromium(VI) in aqueous solutions by ion chromatography and chemiluminescence detection

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Jøns, O; Nielsen, B

    1992-01-01

    A method for the simultaneous determination of chromium(iii) and chromium(vi) in a flow system based on chemiluminescence was developed. A Dionex cation-exchange guard column was used to separate chromium(iii) from chromium(vi), and chromium(vi) was reduced by potassium sulfite, whereupon both...... species were detected by use of the luminol-hydrogen peroxide chemiluminescence system. Linear calibration for both species was established over the concentration range 1-1000 micrograms l-1. The precision at the 20 micrograms l-1 level was 3.5% for chromium(iii) and 3.3% for chromium(vi), respectively...

  14. Effect of chromium underlayer on the properties of nano-crystalline diamond films

    Science.gov (United States)

    Garratt, E.; AlFaify, S.; Yoshitake, T.; Katamune, Y.; Bowden, M.; Nandasiri, M.; Ghantasala, M.; Mancini, D. C.; Thevuthasan, S.; Kayani, A.

    2013-01-01

    This paper investigated the effect of chromium underlayer on the structure, microstructure, and composition of the nano-crystalline diamond films. Nano-crystalline diamond thin films were deposited at high temperature in microwave-induced plasma diluted with nitrogen, on single crystal silicon substrate with a thin film of chromium as an underlayer. Characterization of the film was implemented using non-Rutherford backscattering spectrometry, Raman spectroscopy, near-edge x-ray absorption fine structure, x-ray diffraction, and atomic force microscopy. Nanoindentation studies showed that the films deposited on chromium underlayer have higher hardness values compared to those deposited on silicon without an underlayer. Diamond and graphitic phases of the films evaluated by x-ray and optical spectroscopic analyses determined consistency between the sp2 and sp3 phases of carbon in chromium sample to that of diamond grown on silicon. Diffusion of chromium was observed using ion beam analysis which was correlated with the formation of chromium complexes by x-ray diffraction.

  15. A novel surface cleaning method for chemical removal of fouling lead layer from chromium surfaces

    Science.gov (United States)

    Gholivand, Kh.; Khosravi, M.; Hosseini, S. G.; Fathollahi, M.

    2010-10-01

    Most products especially metallic surfaces require cleaning treatment to remove surface contaminations that remain after processing or usage. Lead fouling is a general problem which arises from lead fouling on the chromium surfaces of bores and other interior parts of systems which have interaction with metallic lead in high temperatures and pressures. In this study, a novel chemical solution was introduced as a cleaner reagent for removing metallic lead pollution, as a fouling metal, from chromium surfaces. The cleaner aqueous solution contains hydrogen peroxide (H 2O 2) as oxidizing agent of lead layer on the chromium surface and acetic acid (CH 3COOH) as chelating agent of lead ions. The effect of some experimental parameters such as acetic acid concentration, hydrogen peroxide concentration and temperature of the cleaner solution during the operation on the efficiency of lead cleaning procedure was investigated. The results of scanning electron microscopy (SEM) showed that using this procedure, the lead pollution layer could be completely removed from real chromium surfaces without corrosion of the original surface. Finally, the optimum conditions for the complete and fast removing of lead pollution layer from chromium surfaces were proposed. The experimental results showed that at the optimum condition (acetic acid concentration 28% (V/V), hydrogen peroxide 8% (V/V) and temperature 35 °C), only 15-min time is needed for complete removal of 3 g fouling lead from a chromium surface.

  16. The effect of chromium diffusion redistribution on wear resistance of carburized 3Kh13 steel

    International Nuclear Information System (INIS)

    Shcherbedinskij, G.V.; Shumakov, A.I.; Zemskij, S.V.; Pereverzev, V.M.

    1977-01-01

    The redistribution of chromium in steel 3Kh13 on carburization in a high-activity carburizer and the wear-resistance of the steel have been investigated. Surface layers with an increased chromium concentration show the highest wear-resistance. The chromium content in the surface layer increases due to its diffusion from the interior. The distribution of carbon and chromium in the carburized layers has been studied with the aid of the radioactive isotope 14 C by the method of layer-by-layer spectral analysis on a vacuum quantometer, layer-by-layer chemical and X-ray structure analysis. The composition of the carbides has been determined by physicochemical analysis. It has been established that the carburized layer can be divided into four zones with respect to its phase composition: first zone - hematite and spinal with 0.5-2.0% C; second zone - solid carbides (Fe,Cr) 7 C 3 ; up to 5% C; third zone - globular carbides in a troostite matrix (Cr,Fe) 7 C 3 and Cr 23 C 6 ; up to 3.5% C; fourth, transitional, zone - troostite carbide mixture Cr 23 C 6 ; up to 1% C. The chromium diffusion in the carburized layer is faster than in the initial austenite. The chromium counterdiffusion is due to the development of a zone of solid carbides M 7 C 3

  17. Investigating a multi-purpose target for electron linac based photoneutron sources for BNCT of deep-seated tumors

    International Nuclear Information System (INIS)

    Masoudi, S. Farhad; Rasouli, Fatemeh S.

    2015-01-01

    Recent studies in BNCT have focused on investigating appropriate neutron sources as alternatives for nuclear reactors. As the most prominent facilities, the electron linac based photoneutron sources benefit from two consecutive reactions, (e, γ) and (γ, n). The photoneutron sources designed so far are composed of bipartite targets which involve practical problems and are far from the objective of achieving an optimized neutron source. This simulation study deals with designing a compact, optimized, and geometrically simple target for a photoneutron source based on an electron linac. Based on a set of MCNPX simulations, tungsten is found to have the potential of utilizing as both photon converter and photoneutron target. Besides, it is shown that an optimized dimension for such a target slows-down the produced neutrons toward the desired energy range while keeping them economy, which makes achieving the recommended criteria for BNCT of deep-tumors more available. This multi-purpose target does not involve complicated designing, and can be considered as a significant step toward finding application of photoneutron sources for in-hospital treatments. In order to shape the neutron beam emitted from such a target, the beam is planned to pass through an optimized arrangement of materials composed of moderators, filters, reflector, and collimator. By assessment with the recommended in-air parameters, it is shown that the designed beam provides high intensity of desired neutrons, as well as low background contamination. The last section of this study is devoted to investigate the performance of the resultant beam in deep tissue. A typical simulated liver tumor, located within a phantom of human body, was subjected to the irradiation of the designed spectrum. The dosimetric results, including evaluated depth-dose curves and carried out in-phantom parameters show that the proposed configuration establishes acceptable agreement between the appropriate neutron intensity, and

  18. Studies of iron, cobalt and chromium distribution in some continental aquatic ecosystems and biological materials

    International Nuclear Information System (INIS)

    Kostic, K.

    1982-01-01

    The aim of the present work was to investigate iron, cobalt and chromium distribution in samples of living and non-living matter by using instrumental neutron activation analysis (INAA). The samples were irradiated by thermal neutron flux of 1-5x10 17 n/m 2 xs (for 3-7 days). Investigations were carried out starting with water systems components, such also species living in these systems and biological tissues from rat and human organs. The following conclusions have been drawn for elements distribution in the relation environment/living matter: (1) iron, cobalt and chromium contents in plankton are very close to these found in suspended materials; (2) among all the investigated living organisms, the highest contents of investigated elements have been found in fish; (3) inspite of the contents of iron, cobalt and chromium being somewhat lower in bentos and crustacea than in suspended materials, all the obtained values are very close, and (4) human liver has somewhat higher iron- and cobalt- contents than rat liver, which, however, has higher chromium concentration. Of all the investigated living organisms chromium content was the lowest in human liver. (author)

  19. Reaction of Oxygen with Chromium and Chromium Carbide at Low O2 Pressures and High Temperatures

    International Nuclear Information System (INIS)

    Hur, Dong O.; Kang, Sung G.; Paik, Young N.

    1984-01-01

    The oxidation rate of chromium carbide has been measured continuously using thermogravimetric analysis at different oxygen pressures ranging from 1.33x10 -2 to 2.67x10 -1 Pa O 2 at 1000-1300 .deg. C. The oxidation of pure chromium has also been studied between 1000-1300 .deg. C under 6.67x10 -2 Pa O 2 and compared with that of chromium carbide. The oxidation of chromium carbide showed a linear behavior which was different from that of chromium. The oxidation rate of chromium carbide increased with increasing temperature and oxygen pressure was lower than of pure chromium. Above 1200 .deg. C, the volatile oxide was formed and evaporated causing a weight loss. The compositions and morphology of the oxide were studied with X-ray diffractometer and scanning electron microscope, respectively. The morphology of oxide changed with varying temperature and pressure. The oxide scale was consisted of mainly two different layers of Cr 2 O 3 and CrO, and the properties of oxide scale were correlated with oxidation behavior. The oxide film formed in the above test condition has been detached from the carbide surface. The crack and pore were thought to be from CO gas evolving at the interface of chromium carbide and its oxide and the major factor of the linear behavior of chromium carbide

  20. Potential of Live Spirulina platensis on Biosorption of Hexavalent Chromium and Its Conversion to Trivalent Chromium.

    Science.gov (United States)

    Colla, Luciane Maria; Dal'Magro, Clinei; De Rossi, Andreia; Thomé, Antônio; Reinehr, Christian Oliveira; Bertolin, Telma Elita; Costa, Jorge Alberto Vieira

    2015-01-01

    Microalga biomass has been described worldwide according their capacity to realize biosorption of toxic metals. Chromium is one of the most toxic metals that could contaminate superficial and underground water. Considering the importance of Spirulina biomass in production of supplements for humans and for animal feed we assessed the biosorption of hexavalent chromium by living Spirulina platensis and its capacity to convert hexavalent chromium to trivalent chromium, less toxic, through its metabolism during growth. The active biomass was grown in Zarrouk medium diluted to 50% with distilled water, keeping the experiments under controlled conditions of aeration, temperature of 30°C and lighting of 1,800 lux. Hexavalent chromium was added using a potassium dichromate solution in fed-batch mode with the aim of evaluate the effect of several additions contaminant in the kinetic parameters of the culture. Cell growth was affected by the presence of chromium added at the beginning of cultures, and the best growth rates were obtained at lower metal concentrations in the medium. The biomass removed until 65.2% of hexavalent chromium added to the media, being 90.4% converted into trivalent chromium in the media and 9.6% retained in the biomass as trivalent chromium (0.931 mg.g(-1)).

  1. Mechanical properties of metal-ceramic systems from nickel-chromium and cobalt-chromium alloys

    Directory of Open Access Journals (Sweden)

    Mirković Nemanja

    2007-01-01

    Full Text Available Background/Aim. Metal-ceramic bond strength and alloys' elastic modulus clearly determine the potential of alloy application, because the ceramic integrity during mastication depends on these two characteristics. The aim of this study was to evaluate metal-ceramic bond strength and elastic modulus of cobalt-chromium alloys in making porcelainfused- to-metal restorations, regarding the application of the most frequent nickel-chromium alloy. Methods. The research was performed as an experimental study. Six metalceramic samples were made from nickel-chromium alloy (Wiron 99 and cobalt-chromium alloy (Wirobond C, according to the manufactures manuals and instructions from ISO 9693: 1996. Three-point bending test was performed up to the ceramic fracture. The fracture load was measured on an universal testing machine (Zwick, type 1464, with cross-head speed of 0,05mm/min. Results. The results of this study confirmed the significant differences between the metal-ceramic bond strength (p < 0.01 and elastic modulus (p < 0.001 of nickel-chromium and cobalt-chromium alloys, where cobalt-chromium alloys showed higher values for both tested parameters. Conclusion. Cobalt-chromium metal-ceramic alloys can successfully replace nickel-chromium alloys, especially for fabrication of long-span metal-ceramic bridges due to the great flexural strength.

  2. Experimental patch testing with chromium-coated materials.

    Science.gov (United States)

    Bregnbak, David; Thyssen, Jacob P; Jellesen, Morten S; Zachariae, Claus; Johansen, Jeanne D

    2017-06-01

    Chromium coatings on metal alloys can be decorative, and prevent corrosion and metal ion release. We recently showed that handling of a chromium-containing disc resulted in chromium deposition on the skin. To examine patch test reactivity to chromium-coated discs. We included 15 patients: 10 chromium-allergic patients, and 5 patients without chromium allergy. All were patch tested with potassium dichromate, cobalt chloride, nickel sulfate, and nine different metallic discs. The chromium-allergic patients were also patch tested with serial dilutions of potassium dichromate. Positive/weaker reactions were observed to disc B (1 of 10), disc C (1 of 10), and disc D, disc E, and disc I (4 of 10 each). As no controls reacted to any of the discs, the weak reactions indicate allergic reactions. Positive patch test reactions to 1770 ppm chromium(VI) in the serial dilutions of potassium dichromate were observed in 7 of 10 patients. When the case group was narrowed down to include only the patients with a current positive patch test reaction to potassium dichromate, elicitation of dermatitis by both chromium(III) and chromium(VI) discs was observed in 4 of 7 of patients. Many of the patients reacted to both chromium(III) and chromium(VI) surfaces. Our results indicate that both chromium(VI) and chromium(III) pose a risk to chromium-allergic patients. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Simultaneous Investigation of Hot-electron Transport and Preplasma Formation in Cone-wire Targets

    Science.gov (United States)

    Friesen, H.; Tiedje, H. F.; Singh, S.; Tsui, Y. Y.; Fedosejevs, R.; Ma, T.; Hey, D.; Ping, Y.; Chen, C. D.; Macphee, A.; Key, M. H.; McLean, H. S.; Patel, P.; MacKinnon, A.; Pasley, J.; Akli, K. U.; Stephens, R.; Link, A.; Schumacher, D. W.; Freeman, R. R.; van Woerkom, L. D.; Westover, B.; Wei, M. S.; Beg, F. N.

    2010-11-01

    The generation and transport of MeV electrons is essential to the realization of Fast Ignition fusion. An important factor in determining the hot electron source is the preplasma distribution that is inevitably formed even in high-contrast short-pulse laser systems. A larger preplasma moves the critical surface further from the region where heating is required, and has a significant effect on the electron source and transport. In this paper we present analysis of results where bremstrahhlung emission from the preplasma region was imaged simultaneously with k-alpha emission from a copper tracer in cone-wire targets using a grazing-incidence x-Kirkpatrick-Baez x-ray microscope. The predicted scalings from simulations and theory will be compared with experimental results to determine unique characteristics of how the hot electron source and transport are affected by the presence of the wire as well as preplasma.

  4. Specification for corrosion-resisting chromium and chromium-nickel steel welding rods and bare electrodes - approved 1969

    International Nuclear Information System (INIS)

    Anon.

    1975-01-01

    This specification covers corrosion-resisting chromium and chromium-nickel steel welding rods for use with the atomic hydrogen and gas-tungsten-arc welding processes and bare electrodes for use with the submerged arc and gas metal-arc welding processes. These welding rods and electrodes include those alloy steels designated as corrosion- or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4% and nickel does not exceed 50%

  5. Association between maternal urinary chromium and premature rupture of membranes in the Healthy Baby Cohort study in China.

    Science.gov (United States)

    Huang, Sha; Xia, Wei; Li, Yuanyuan; Zhang, Bin; Zhou, Aifen; Zheng, Tongzhang; Qian, Zhengmin; Huang, Zheng; Lu, Shi; Chen, Zhong; Wang, Youjie; Pan, Xinyun; Huo, Wenqian; Jin, Shuna; Jiang, Yangqian; Xu, Shunqing

    2017-11-01

    Chromium exposure from increasing industrial releases has become a threat for pregnant women due to the potential health effects on vulnerable embryos. Previous studies have suggested that maternal chromium exposure is associated with adverse birth outcomes, but no epidemiological research has been conducted to examine the relationship between chromium exposure and premature rupture of membranes (PROM). This study aimed at investigating the association of maternal urinary chromium exposure levels with PROM and was performed with 5408 pregnant women recruited from 2012 to 2014 in the city of Wuhan, China. Maternal urinary chromium collected before labor was adjusted with creatinine, and its association with PROM was evaluated using logistic regression. Each one unit increase in the natural logarithm transformed maternal urinary chromium concentration (μg/g creatinine), an odds ratio (OR) of 1.47 [95% confidence interval (CI): 1.36, 1.58] for PROM was observed. Compared to the lowest tertile of maternal urinary chromium, PROM was positively correlated with increased urinary levels of chromium (adjusted OR = 1.42; 95% CI: 1.09, 1.84 for the medium tertile; adjusted OR = 2.77; 95% CI: 2.18, 3.52 for the highest tertile). Additionally, the association of chromium with PROM appeared to be more significant among male infants (adjusted OR = 3.52; 95% CI: 2.51, 4.94 for the highest tertile) than female infants (adjusted OR = 2.16; 95% CI: 1.52, 3.06 for the highest tertile) (p for interaction = 0.05). Our large birth cohort showed an association between maternal urinary chromium levels and PROM, and the association may differ by infant gender. Further studies from different populations are needed to confirm the observed association. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Synthesis and investigation of CrB{sub 4}, MnB{sub 4} and new ternary chromium and rhenium manganese borides; Synthese und Untersuchung von CrB{sub 4}, MnB{sub 4} sowie neuen ternaeren Chrom- und Rheniummanganboriden

    Energy Technology Data Exchange (ETDEWEB)

    Knappschneider, Arno

    2014-10-13

    In the present work single crystals of the tetraborides of chromium and manganese have been grown and allowed a structure refinement of the compounds. Furthermore the physical characteristics for example hardness, electronic properties and magnetism were been determined. Also the ternary tetraboride phase of chromium and manganese was synthesized and a new ternary rhenium manganese diboride could be obtained.

  7. VOLTAMMETRIC INVESTIGATION OF THE DISTRIBUTION OF ...

    African Journals Online (AJOL)

    VOLTAMMETRIC INVESTIGATION OF THE DISTRIBUTION OF HYDROXO-, CHLORO-, EDTA AND CARBOHYDRATE COMPLEXES OF LEAD, CHROMIUM, ZINC, CADMIUM AND COPPER: POTENTIAL APPLICATION TO METAL SPECIATION STUDIES IN BREWERY WASTEWATER.

  8. Lead and chromium removal from leachate using horsetail (Equisetum hyemale

    Directory of Open Access Journals (Sweden)

    E. Kurniati

    2014-01-01

    Full Text Available Phytoremediation has been widely used for wastewater treatment technology. Horsetail was investigated for its capacity to remediate lead and chromium in leachate. This plant seemed to be an effective choice for phytoremediation due to its survival in extreme to moderate conditions, the availability of annual or perennial varieties and a deep root system. Conducted in a greenhouse, this research used leachate from final disposal. The leachate was exposed to six treated plants with three multiplications using activated natural zeolite media for one month. The treatments were flow system i.e. batch and continue, and living plants weight that is 0, 153 and 306 g planted in 20 cm diameter and 30 cm deep pots. The leachate pH, temperature, lead, and chromium concentration were observed and also the surrounding temperature and humidity. Results showed that 82.2% of lead can be removed by 153 gram horsetail on batch system as well as 61.2% chromium removal by 153 gram horsetail on continue system. Horsetail seemed to have future to be applied in phytoremediation of artisanal and small scale mining waste.

  9. A targeted investigation to demonstrate the freedom of West Timor from HPAI H5N1.

    Science.gov (United States)

    Bulu, Petrus Malo; Robertson, Ian D; Geong, Maria

    2018-02-01

    In early 2004 highly pathogenic avian influenza (HPAI) H5N1 virus caused major outbreaks of disease in poultry in Indonesia. The disease was first reported in West Timor in eastern Indonesia in the same year, resulting in the death of approximately one hundred chickens from both commercial and backyard farms; however no evidence of disease has subsequently been reported in West Timor since 2007. A targeted survey was undertaken in 2013 in 2 districts of West Timor. Three hundred village and commercial poultry (292 chickens and 8 Muscovy ducks) from 10 villages and 5 live bird markets (LBMs) were sampled between August and October 2013. Swabs of the cloaca and trachea of the sampled birds were tested using the Anigen ® Rapid Test (Bionote). All samples were negative on testing (0%; 95%CI: 0.0-1.2%). From these results it was concluded with a high level of confidence (100%, 95%CI: 99.988, 100) that this population is not infected, and these results, along with a lack of clinical evidence of disease, support the conclusion that West Timor was free from HPAI infection at the time of the survey. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Investigation and conformational analysis of fluorinated nucleoside antibiotics targeting siderophore biosynthesis.

    Science.gov (United States)

    Dawadi, Surendra; Viswanathan, Kishore; Boshoff, Helena I; Barry, Clifton E; Aldrich, Courtney C

    2015-05-15

    Antibiotic resistance represents one of the greatest threats to public health. The adenylation inhibitor 5'-O-[N-(salicyl)sulfamoyl]adenosine (SAL-AMS) is the archetype for a new class of nucleoside antibiotics that target iron acquisition in pathogenic microorganisms and is especially effective against Mycobacterium tuberculosis, the causative agent of tuberculosis. Strategic incorporation of fluorine at the 2' and 3' positions of the nucleoside was performed by direct fluorination to enhance activity and improve drug disposition properties. The resulting SAL-AMS analogues were comprehensively assessed for biochemical potency, whole-cell antitubercular activity, and in vivo pharmacokinetic parameters. Conformational analysis suggested a strong preference of fluorinated sugar rings for either a 2'-endo, 3'-exo (South), or a 3'-endo,2'-exo (North) conformation. The structure-activity relationships revealed a strong conformational bias for the C3'-endo conformation to maintain potent biochemical and whole-cell activity, whereas improved pharmacokinetic properties were associated with the C2'-endo conformation.

  11. REMOVAL OF HEXAVALENT CHROMIUM FROM DRINKING WATER

    Directory of Open Access Journals (Sweden)

    A. R. Asgari ، F. Vaezi ، S. Nasseri ، O. Dördelmann ، A. H. Mahvi ، E. Dehghani Fard

    2008-10-01

    Full Text Available Removal of chromium can be accomplished by various methods but none of them is cost-effective in meeting drinking water standards. For this study, granular ferric hydroxide was used as adsorbent for removal of hexavalent chromium. Besides, the effects of changing contact time, pH and concentrations of competitive anions were determined for different amounts of granular ferric hydroxide. It was found that granular ferric hydroxide has a high capacity for adsorption of hexavalent chromium from water at pH≤7 and in 90 min contact time. Maximum adsorption capacity was determined to be 0.788 mg Cr+6/g granular ferric hydroxide. Although relatively good adsorption of sulfate and chloride had been specified in this study, the interfering effects of these two anions had not been detected in concentrations of 200 and 400 mg/L. The absorbability of hexavalent chromium by granular ferric hydroxide could be expressed by Freundlich isotherm with R2>0.968. However, the disadvantage was that the iron concentration in water was increased by the granular ferric hydroxide. Nevertheless, granular ferric hydroxide is a promising adsorbent for chromium removal, even in the presence of other interfering compounds, because granular ferric hydroxide treatment can easily be accomplished and removal of excess iron is a simple practice for conventional water treatment plants. Thus, this method could be regarded as a safe and convenient solution to the problem of chromium-polluted water resources.

  12. Chromium in human nutrition: a review.

    Science.gov (United States)

    Mertz, W

    1993-04-01

    This review summarizes the results of 15 controlled studies supplementing defined Cr(III) compounds to subjects with impaired glucose tolerance. Three of these (3-4 mumol Cr/d for > 2 mo) produced no beneficial effects: serum glucose, insulin and lipid concentrations remained unchanged. The remaining 12 interventions improved the efficiency of insulin or the blood lipid profile of subjects (ranging from malnourished children and healthy middle-aged individuals to insulin-requiring diabetics). In addition, three cases of impaired glucose tolerance after long-term total parenteral alimentation responding to Cr supplementation have been reported. Chromium potentiates the action of insulin in vitro and in vivo; maximal in vitro activity requires a special chemical form, termed Glucose Tolerance Factor and tentatively identified as a Cr-nicotinic acid complex. Its complete structural identification is a major challenge to chromium research. The development and validation of a procedure to diagnose chromium status is the second challenge. Such a test would allow the assessment of incidence and severity of deficiency in the population and the selection of deficiency in the population and the selection of chromium-responsive individuals. The third challenge is the definition of chromium's mode of action on parameters of lipid metabolism that have been reported from some studies but not others. Future research along these lines might establish whether chromium deficiency is a factor in the much discussed "Syndrome X" of insulin resistance.

  13. Effects of metals cadmium and chromium alone and in combination on the liver and kidney tissue of male Spraque-Dawley rats: An ultrastructural and electron-energy-loss spectroscopy investigation.

    Science.gov (United States)

    Venter, Chantelle; Oberholzer, Hester Magdalena; Cummings, Franscious Riccardo; Bester, Megan Jean

    2017-08-01

    Heavy metal pollution has increased in the last decades. Water sources are contaminated and human exposure is often long term exposure to variable amounts of different metals. In this study, male Sprague-Dawley rats were exposed via oral gavage for 28 days to cadmium (Cd) and chromium (Cr), alone and in combination at concentrations 1000 times the human World Health Organization's acceptable water limits. Rat equivalent dosages were used. Blood markers of liver and kidney function were measured, changes to cellular morphology was determined with transmission electron microscopy and the intracellular metal localisation was determined with the electron energy-loss spectroscopy and energy filtered transmission electron microscopy analysis. Both Cd and Cr caused changes to the nuclear and mitochondrial membranes and irregular chromatin condensation of hepatocytes. Cr exposure caused dilation of the rough endoplasmic reticulum (rER). The combination caused nuclear and mitochondrial membrane damage as well as irregular chromatin condensation. In the kidney tissue, Cd caused irregular chromatin condensation in the cells of the proximal convoluted tubule (PCT). Cr caused changes to the outer nuclear and mitochondrial membrane and chromatin structure. The combination group caused membrane damage, irregular chromatin condensation and rER changes in the PCT. All the metal groups showed damage to the endothelial cells and pedicles, but not to the mesangial cells. Cd and Cr bio-accumulation was observed in the nucleus, mitochondria and rER of the liver and kidney and therefore are responsible for the cellular observed damage that can cause functional changes to the tissues and organs. © 2017 Wiley Periodicals, Inc.

  14. Investigating Spatial Patterns of Persistent Scatterer Interferometry Point Targets and Landslide Occurrences in the Arno River Basin

    Directory of Open Access Journals (Sweden)

    Ping Lu

    2014-07-01

    Full Text Available Persistent Scatterer Interferometry (PSI has been widely used for landslide studies in recent years. This paper investigated the spatial patterns of PSI point targets and landslide occurrences in the Arno River basin in Central Italy. The main purpose is to analyze whether spatial patterns of Persistent Scatterers (PS can be recognized as indicators of landslide occurrences throughout the whole basin. The bivariate K-function was employed to assess spatial relationships between PS and landslides. The PSI point targets were acquired from almost 4 years (from March 2003 to January 2007 of RADARSAT-1 images. The landslide inventory was collected from 15 years (from 1992–2007 of surveying and mapping data, mainly including remote sensing data, topographic maps and field investigations. The proposed approach is able to assess spatial patterns between a variety of PS and landslides, in particular, to understand if PSI point targets are spatially clustered (spatial attraction or randomly distributed (spatial independency on various types of landslides across the basin. Additionally, the degree and scale distances of PS clustering on a variety of landslides can be characterized. The results rejected the null hypothesis that PSI point targets appear to cluster similarly on four types of landslides (slides, flows, falls and creeps in the Arno River basin. Significant influence of PS velocities and acquisition orbits can be noticed on detecting landslides with different states of activities. Despite that the assessment may be influenced by the quality of landslide inventory and Synthetic Aperture Radar (SAR images, the proposed approach is expected to provide guidelines for studies trying to detect and investigate landslide occurrences at a regional scale through spatial statistical analysis of PS, for which an advanced understanding of the impact of scale distances on landslide clustering is fundamentally needed.

  15. Permeation of chromium salts through human skin in vitro

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Fullerton, A; Avnstorp, C

    1992-01-01

    Chromium permeation studies were performed on full thickness human skin in diffusion cells. All samples were analysed for the total chromium content by graphite furnace Zeeman-corrected atomic absorption spectrometry. Some samples were analysed by an ion chromatographic method permitting...... the simultaneous determination of Cr(VI) and Cr(III) as well. The amounts of chromium found in all skin layers were significantly higher when potassium dichromate was applied to the skin compared with chromium chloride or chromium nitrate. Chromium could only be detected in the recipient phase after application...... of the dichromate solution. Chromium skin levels increased with increasing concentrations of applied chromium salts up to 0.034 M Cr. The amount of chromium in recipient phase and skin layers increased with increasing pH when the applied solution contained potassium dichromate. This was ascribed to a decreased skin...

  16. Investigation of Control System and Display Variations on Spacecraft Handling Qualities for Docking with Stationary and Rotating Targets

    Science.gov (United States)

    Jackson, E. Bruce; Goodrich, Kenneth H.; Bailey, Randall E.; Barnes, James R.; Ragsdale, William A.; Neuhaus, Jason R.

    2010-01-01

    This paper documents the investigation into the manual docking of a preliminary version of the Crew Exploration Vehicle with stationary and rotating targets in Low Earth Orbit. The investigation was conducted at NASA Langley Research Center in the summer of 2008 in a repurposed fixed-base transport aircraft cockpit and involved nine evaluation astronauts and research pilots. The investigation quantified the benefits of a feed-forward reaction control system thruster mixing scheme to reduce translation-into-rotation coupling, despite unmodeled variations in individual thruster force levels and off-axis center of mass locations up to 12 inches. A reduced rate dead-band in the phase-plane attitude controller also showed some promise. Candidate predictive symbology overlaid on a docking ring centerline camera image did not improve handling qualities, but an innovative attitude status indicator symbol was beneficial. The investigation also showed high workload and handling quality problems when manual dockings were performed with a rotating target. These concerns indicate achieving satisfactory handling quality ratings with a vehicle configuration similar to the nominal Crew Exploration Vehicle may require additional automation.

  17. Recovery of Chromium Ions From Electroplating Wastewater by Flotation, Gamma Irradiation and Adsorption onto Hydrogels

    International Nuclear Information System (INIS)

    Eid, M.; Dessouki, A.M.; Omar, A.M.

    2005-01-01

    At present, the wastewater treatment facilities in many plating plants are approaching their time for replacement. On this occasion there is a strong requirement to re-evaluate the wastewater treatment measures from the point of view of treatment technology. Laboratory investigation was undertaken on the flotation of Cr (VI) from aqueous suspension over whole ph range, aiming at the separation of chromium by flotation. The cationic surfactant (hexadecyl triethyl ammonium bromide) was applied as a collector. Surface properties, in particular the critical micelle concentration, the effectiveness of surface tension reduction, efficiency, surface excess and the minimum surface area were measured at 30 μ C. The electro-flotation was applied with and without the collector at different times for the removal of chromium (VI). The results were discussed in term of surface properties of the collectors at the solution/air interface. Further work took place by irradiating the water samples by gamma- irradiation to reduce the highly toxic Cr(VI) to the much less toxic and less soluble Cr1 in water; therefore, there is a potential for the complete removal of chromium from aqueous solutions. The possibility of using hydrogels for the uptake of irradiated chromium solutions by different hydrogels was investigated. The structure of the hydrogels was estimated by using FT1R and the pore structure of the hydrogels before and after dictating with chromium ions was monitored by SEM. The adsorption studies show that, it is ph dependent. Lowering of the chromium concentration below the maximum permissible value have been achieved after the treatment of chromium solution by flotation, gamma irradiation and adsorption onto hydrogels

  18. A novel solid phase extraction procedure on Amberlite XAD-1180 for speciation of Cr(III), Cr(VI) and total chromium in environmental and pharmaceutical samples

    International Nuclear Information System (INIS)

    Narin, Ibrahim; Kars, Ayse; Soylak, Mustafa

    2008-01-01

    Due to the toxicity of chromium, species depend on their chemical properties and bioavailabilities, speciation of chromium is very important in environmental samples. A speciation procedure for chromium(III), chromium(VI) and total chromium in environmental samples is presented in this work, prior to flame atomic absorption spectrometric determination of chromium. The procedure is based on the adsorption of Cr(III)-diphenylcarbazone complex on Amberlite XAD-1180 resin. After oxidation of Cr(III), the developed solid phase extraction system was applied to determinate the total chromium. Cr(III) was calculated as the difference between the total Cr content and the Cr(VI) content. The analytical conditions for the quantitative recoveries of Cr(VI) on Amberlite XAD-1180 resin were investigated. The effects of some alkaline, earth alkaline, metal ions and also some anions were also examined. Preconcentration factor was found to be 75. The detection limits (LOD) based on three times sigma of the blank (N: 21) for Cr(VI) and total chromium were 7.7 and 8.6 μg/L, respectively. Satisfactory results for the analysis of total chromium in the stream sediment (GBW7310) certified reference material for the validation of the presented method was obtained. The procedure was applied to food, water and pharmaceutical samples successfully

  19. Chromium getter studies in TFTR

    International Nuclear Information System (INIS)

    Dylla, H.F.; LaMarche, P.H.; Blanchard, W.R.

    1986-02-01

    We have studied the effects of the deposition of thin films (approx.0.1 μm) of chromium onto approx.70% of the torus area of the Tokamak Fusion Test Reactor (TFTR). The purpose of these experiments was to test the difference between high surface coverage and high pumping speed gettering schemes with respect to minimizing oxygen impurity generation in high power tokamak discharges. The initial Cr deposition had significant effects on vessel outgassing and subsequent plasma performance: the outgassing of H 2 O, CO, and CO 2 decreased by a factor of ten, oxygen impurity radiation decreased by a factor of two, the plasma Z/sub eff/ decreased from 1.3 to 1.1, and the plasma density limit increased by 20%. This improvement correlates with a significant reduction of the edge radiation as the density limit is approached. The effects of the initial and subsequent Cr depositions were relatively long lasting, exhibiting time constants of the order of weeks. We attribute the observed impurity reduction to a modification of the oxide surface on the vessel wall, which is apparently a significant impurity source for oxygen. 17 refs., 6 figs

  20. Genesis and transport of hexavalent chromium in the system ophiolitic rocks - groundwater

    Science.gov (United States)

    Shchegolikhina, Anastasia; Guadagnini, Laura; Guadagnini, Alberto

    2015-04-01

    Our study aims at contributing to the quantification and characterization of chromium transport processes from host rocks and soil matrices to groundwater. We focus on dissolved hexavalent chromium detected in groundwaters of geological regions with ophiolitic rocks (ophiolites and serpentinites) inclusions due to its critical ecological impact. (Oze et al., 2004). Despite the large number of analyses on the occurrence of high concentrations of hazardous hexavalent chromium ions in natural waters, only few studies were performed with the objective of identifying and investigating the geochemical reactions which could occur in the natural system rock - groundwater - dissolved chromium (Fantoni et al., 2002, Stephen and James, 2004, Lelli et al., 2013). In this context, there is a need for integration of results obtained from diverse studies in various regions and settings to improve our knowledge repository. Our theoretical analyses are grounded and driven by practical scenarios detected in subsurface reservoirs exploited for civil and industrial use located in the Emilia-Romagna region (Italy). Available experimental datasets are complemented with data from other international regional-scale settings (Altay mountains region, Russia). Modeling of chromium transformation and migration particularly includes characterization of the multispecies geochemical system. A key aspect of our study is the analysis of the complex competitive sorption processes governing heavy metal evolution in groundwater. The results of the research allow assessing the critical qualitative features of the mechanisms of hexavalent chromium ion mobilization from host rocks and soils and the ensuing transformation and migration to groundwater under the influence of diverse environmental factors. The study is then complemented by the quantification of the main sources of uncertainty associated with prediction of heavy metal contamination levels in the groundwater system explored. Fantoni, D

  1. On the Orientation Error of IMU: Investigating Static and Dynamic Accuracy Targeting Human Motion.

    Directory of Open Access Journals (Sweden)

    Luca Ricci

    Full Text Available The accuracy in orientation tracking attainable by using inertial measurement units (IMU when measuring human motion is still an open issue. This study presents a systematic quantification of the accuracy under static conditions and typical human dynamics, simulated by means of a robotic arm. Two sensor fusion algorithms, selected from the classes of the stochastic and complementary methods, are considered. The proposed protocol implements controlled and repeatable experimental conditions and validates accuracy for an extensive set of dynamic movements, that differ in frequency and amplitude of the movement. We found that dynamic performance of the tracking is only slightly dependent on the sensor fusion algorithm. Instead, it is dependent on the amplitude and frequency of the movement and a major contribution to the error derives from the orientation of the rotation axis w.r.t. the gravity vector. Absolute and relative errors upper bounds are found respectively in the range [0.7° ÷ 8.2°] and [1.0° ÷ 10.3°]. Alongside dynamic, static accuracy is thoroughly investigated, also with an emphasis on convergence behavior of the different algorithms. Reported results emphasize critical issues associated with the use of this technology and provide a baseline level of performance for the human motion related application.

  2. On the Orientation Error of IMU: Investigating Static and Dynamic Accuracy Targeting Human Motion.

    Science.gov (United States)

    Ricci, Luca; Taffoni, Fabrizio; Formica, Domenico

    2016-01-01

    The accuracy in orientation tracking attainable by using inertial measurement units (IMU) when measuring human motion is still an open issue. This study presents a systematic quantification of the accuracy under static conditions and typical human dynamics, simulated by means of a robotic arm. Two sensor fusion algorithms, selected from the classes of the stochastic and complementary methods, are considered. The proposed protocol implements controlled and repeatable experimental conditions and validates accuracy for an extensive set of dynamic movements, that differ in frequency and amplitude of the movement. We found that dynamic performance of the tracking is only slightly dependent on the sensor fusion algorithm. Instead, it is dependent on the amplitude and frequency of the movement and a major contribution to the error derives from the orientation of the rotation axis w.r.t. the gravity vector. Absolute and relative errors upper bounds are found respectively in the range [0.7° ÷ 8.2°] and [1.0° ÷ 10.3°]. Alongside dynamic, static accuracy is thoroughly investigated, also with an emphasis on convergence behavior of the different algorithms. Reported results emphasize critical issues associated with the use of this technology and provide a baseline level of performance for the human motion related application.

  3. Investigation of Welfare Impacts of Targeting Subsidies on Fishery Households in Fars Province

    Directory of Open Access Journals (Sweden)

    seyed nemat mousavi

    2015-05-01

    Full Text Available Pisciculture, especially in countries which are unable to develop their marine resources, is a desired to provide part of their food and protein needs. This study aims at investigating welfare impacts of energy subsidy removal on fish producers in Fars province. To achieve the objective, cross-sectional data obtained from fish producers of Fars Province in 2010 was used. Cost, input demand and production functions were estimated using the collected data. The findings showed that in Fars Province removing fuel subsidies is led to decreased demand for fuel and production as well as a reduction in producers' revenue. As a result of that, in Fars Province benefits from fish are reduced by0.16 percent .The results also showed that food is the most important input in the fish production.a10 percent increases in food consumption is expected to raise the fish production by 4.8 percent. On the other hand, a 50 percent increase in the energy price will reduce the energy consumption by 9.5 percent, and as a result of that, the production and the benefit will be reduced by 0.057% (0.036 tons and 0.06%, respectively. Regarding the importance of food in production, it is suggested to focus on improving the food productivity.

  4. 76 FR 77013 - Tin- and Chromium-Coated Steel Sheet From Japan; Scheduling of a Full Five-Year Review Concerning...

    Science.gov (United States)

    2011-12-09

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-860 (Second Review)] Tin- and Chromium-Coated Steel Sheet From Japan; Scheduling of a Full Five-Year Review Concerning the Antidumping Duty... order on tin- and chromium-coated steel sheet from Japan would be likely to lead to continuation or...

  5. Electrochemical and chemical corrosion of chromium

    International Nuclear Information System (INIS)

    Drazic, Dragutin M.; Popic, Jovan P.

    2004-01-01

    It was shown that chromium in deaerated sulfuric acid of pH 1 exhibits two stable corrosion potentials, depending whether the metal had previously been in contact with air or subjected to activation by cathodic evolving hydrogen. Electrochemical polarization measurements, as well as the measurements of the actual metal dissolution rate at the corrosion potential, anodic or cathodic polarization, using the analytical determination of Cr ions in the solution, or volumes of hydrogen evolved, showed that hydrogen can evolve on chromium by three different reaction mechanisms. The first one is the electrochemical hydrogen evolution reaction from H + ions at the bare chromium surface obtained by cathodic activation. This reaction and the active anodic dissolution of chromium determine one stable corrosion potential. The second reaction is the reaction of H + ions on the oxidized chromium surface which, coupled with the anodic dissolution of passivated chromium determines the other stable corrosion potential. The third one is the 'anomalous' or chemical reaction of chromium with water molecules and hydrogen ions whereby hydrogen is liberated. This is a potential independent reaction, occurring on the bare metal surface, and which is at pH 1 several times faster at the corrosion potential than the electrochemical hydrogen evolution reaction. The consequence is that the overall corrosion rate is several times faster than that determined by the usual electrochemical methods. The measurements were performed in the temperature interval 20 - 65 o C and apparent energies of activation for anodic, cathodic and anomalous dissolution reactions were estimated as 63.1, 19.5 and 66.9 kJ mol -1 , respectively. This implies that the anomalous dissolution rate increases more with the increase of temperature than the electrochemical corrosion rate. The applicability of the different methods of measuring electrochemical corrosion rates is discussed. (Author)

  6. Image quality assessment using the dead leaves target: experience with the latest approach and further investigations

    Science.gov (United States)

    Artmann, Uwe

    2015-02-01

    The so-called texture loss is a critical parameter in the objective image quality assessment of todays cameras. Especially cameras build in mobile phones show significant loss of low contrast, fine details which are hard to describe using standard resolution measurement procedures. The combination of very small form factor and high pixel count leads to a high demand of noise reduction in the signal-processing pipeline of these cameras. Different work groups within ISO and IEEE are investigating methods to describe the texture loss with an objective method. The so-called dead leaves pattern has been used for quite a while in this context. Image Engineering presented a new intrinsic approach at the Electronic Imaging Conference 2014, which promises to solve the open issue of the original approach, which could be influenced by noise and artifacts. In this paper, we present our experience with the new approach for a large set of different imaging devices. We show, that some sharpening algorithm found in todays cameras can significantly influence the Spatial Frequency Response based on the Dead Leaves structure (SFRDeadLeaves) results and therefore make an objective evaluation of the perceived image quality even harder. For an objective comparison of cameras, the resulting SFR needs to be reduced to a small set of numbers, ideally a single number. The observed sharpening algorithms lead to much better numerical results, while the image quality already degrades due to strong sharpening. So the measured, high SFRDeadLeaves result is not wrong, as it reflects the artificially enhanced SFR, but the numerical result cannot be used as the only number to describe the image quality. We propose to combine the SFRDeadLeaves measurement with other SFR measurement procedures as described in ISO12233:2014. Based on the three different SFR functions using the dead leaves pattern, sinusoidal Siemens Stars and slanted edges, it is possible to obtain a much better description if the

  7. Investigation of ultrashort pulse laser ablation of solid targets by measuring the ablation-generated momentum using a torsion pendulum.

    Science.gov (United States)

    Zhang, Nan; Wang, Wentao; Zhu, Xiaonong; Liu, Jiansheng; Xu, Kuanhong; Huang, Peng; Zhao, Jiefeng; Li, Ruxin; Wang, Mingwei

    2011-04-25

    50 fs - 12 ps laser pulses are employed to ablate aluminum, copper, iron, and graphite targets. The ablation-generated momentum is measured with a torsion pendulum. Corresponding time-resolved shadowgraphic measurements show that the ablation process at the optimal laser fluence achieving the maximal momentum is primarily dominated by the photomechanical mechanism. When laser pulses with specific laser fluence are used and the pulse duration is tuned from 50 fs to 12 ps, the generated momentum firstly increases and then remains almost constant, which could be attributed to the change of the ablation mechanism involved from atomization to phase explosion. The investigation of the ablation-generated momentum also reveals a nonlinear momentum-energy conversion scaling law, namely, as the pulse energy increases, the momentum obtained by the target increases nonlinearly. This may be caused by the effective reduction of the dissipated energy into the surrounding of the ablation zone as the pulse energy increases, which indicates that for femtosecond laser the dissipated energy into the surrounding target is still significant.

  8. Investigation of the effects of tumor size and type of radionuclide on tumor curability in targeted radiotherapy

    Directory of Open Access Journals (Sweden)

    Hassan Ranjbar

    2015-07-01

    Full Text Available Background: Targeted radiotherapy is one of the important methods of radiotherapy that involves the use of beta-emitting radionuclides to deliver a dose of radiation to tumor cells. An important feature of this method is the tumor size and the finite range of beta particles emitted as a result of radionuclide disintegration those have significant effects for the curability of tumors. Material and Methods: Monte Carlo simulations and mathematical models have been used to investigate the relationship of curability to tumors size for tumors treated with targeted 131I and 90Y. The model assumed that radionuclides are distributed uniformly throughout tumors. Results: The results show that there is an optimal tumor size for cure. For any given cumulated activity, cure probability is greatest for tumors whose diameter is close to the optimum value. There is a maximum value of curability that occurs at a diameter of approximately 3.5 mm for 131I. For 90Y maximum curability occurs at a tumor diameter of approximately 3.5 cm. Tumors smaller than the optimal size are less vulnerable to irradiation from radionuclides because a significant proportion of the disintegration energy escapes and is deposited outside the tumor volume. Tumors larger than the optimal size are less curable because of greater clonogenic cell number. Conclusion: With single radionuclide targeted radiotherapy, there is an optimal tumor size for tumor cure. It is suggested that single agent targeted radiotherapy should not be used for treatment of disseminated disease when multiple tumors of differing size may be present. The use of several radionuclides concurrently would be more effective than reliance on single radionuclide. This approach of using combination of radionuclides with complementary properties could hopefully prepare new measures and improve the efficiency of tumor therapy.

  9. Systems Biology-Based Investigation of Cellular Antiviral Drug Targets Identified by Gene-Trap Insertional Mutagenesis.

    Directory of Open Access Journals (Sweden)

    Feixiong Cheng

    2016-09-01

    Full Text Available Viruses require host cellular factors for successful replication. A comprehensive systems-level investigation of the virus-host interactome is critical for understanding the roles of host factors with the end goal of discovering new druggable antiviral targets. Gene-trap insertional mutagenesis is a high-throughput forward genetics approach to randomly disrupt (trap host genes and discover host genes that are essential for viral replication, but not for host cell survival. In this study, we used libraries of randomly mutagenized cells to discover cellular genes that are essential for the replication of 10 distinct cytotoxic mammalian viruses, 1 gram-negative bacterium, and 5 toxins. We herein reported 712 candidate cellular genes, characterizing distinct topological network and evolutionary signatures, and occupying central hubs in the human interactome. Cell cycle phase-specific network analysis showed that host cell cycle programs played critical roles during viral replication (e.g. MYC and TAF4 regulating G0/1 phase. Moreover, the viral perturbation of host cellular networks reflected disease etiology in that host genes (e.g. CTCF, RHOA, and CDKN1B identified were frequently essential and significantly associated with Mendelian and orphan diseases, or somatic mutations in cancer. Computational drug repositioning framework via incorporating drug-gene signatures from the Connectivity Map into the virus-host interactome identified 110 putative druggable antiviral targets and prioritized several existing drugs (e.g. ajmaline that may be potential for antiviral indication (e.g. anti-Ebola. In summary, this work provides a powerful methodology with a tight integration of gene-trap insertional mutagenesis testing and systems biology to identify new antiviral targets and drugs for the development of broadly acting and targeted clinical antiviral therapeutics.

  10. Investigations of charge-changing processes for light proton-rich nuclei on carbon and solid-hydrogen targets

    Energy Technology Data Exchange (ETDEWEB)

    Sawahata, K. [Institute of Physics, University of Tsukuba, Ibaraki 305-8571 (Japan); Ozawa, A., E-mail: ozawa@tac.tsukuba.ac.jp [Institute of Physics, University of Tsukuba, Ibaraki 305-8571 (Japan); Saito, Y.; Abe, Y.; Ichikawa, Y.; Inaba, N.; Ishibashi, Y. [Institute of Physics, University of Tsukuba, Ibaraki 305-8571 (Japan); Kitagawa, A. [National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Matsunaga, S. [Department of Physics, Saitama University, Saitama 338-8570 (Japan); Moriguchi, T.; Nagae, D.; Okada, S. [Institute of Physics, University of Tsukuba, Ibaraki 305-8571 (Japan); Sato, S. [National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Suzuki, S. [Institute of Physics, University of Tsukuba, Ibaraki 305-8571 (Japan); Suzuki, T.; Takeuchi, Y.; Yamaguchi, T. [Department of Physics, Saitama University, Saitama 338-8570 (Japan); Zenihiro, J. [RIKEN Nishina Center, Wako, Saitama 351-0198 (Japan)

    2017-05-15

    We investigated charge-changing processes (total charge-changing cross sections and partial charge-changing cross sections) for light proton-rich nuclei ({sup 34–36}Ar, {sup 33}Cl, {sup 25–28}Si) at around 300A MeV on carbon and solid-hydrogen targets. We estimated the nuclear proton point radii of {sup 33}Cl and {sup 25,26,27}Si from the observed total charge-changing cross sections by using Glauber-model calculations with a phenomenological correction factor. Furthermore, we estimated the proton skin thickness for {sup 33}Cl coupled with its previously observed matter radius. From investigations of the partial charge-changing cross sections, clear zigzag pattern was observed for all isotopes. The present studies suggest that the pattern may be common in the proton-rich side, and depends on the odd–even nature of the fragment charge.

  11. Surface Chemistry and Spectroscopy of Chromium in Inorganic Oxides

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Wachs, I.E.; Schoonheydt, R.A.

    1996-01-01

    Focuses on the surface chemistry and spectroscopy of chromium in inorganic oxides. Characterization of the molecular structures of chromium; Mechanics of hydrogenation-dehydrogenation reactions; Mobility and reactivity on oxidic surfaces.

  12. Interaction of the wood surface with metal ions. Part 3: The effects of light on chromium impregnated wood surface

    International Nuclear Information System (INIS)

    Stipta, J.; Németh, K.; Molnárné Hamvas, L.

    2004-01-01

    UV-light changes of untreated and chromium impregnated wood surface were investigated by absorption spectrophotometric methods. The properties of indifferent silicagel and celulose layers were to the behaviour of poplar and black locust surface. Chromic-ion-impregnation had no significant effect on the absorption spectra of these layers. On the other hand, hexavalent chromium was reduced and UV-light caused irreversible wood degradation. Surface treatment caused considerable modification in black locust

  13. Response surface optimization, Ex vivo and In vivo investigation of nasal spanlastics for bioavailability enhancement and brain targeting of risperidone.

    Science.gov (United States)

    Abdelrahman, Fatma Elzahraa; Elsayed, Ibrahim; Gad, Mary Kamal; Elshafeey, Ahmed Hassen; Mohamed, Magdi Ibrahim

    2017-09-15

    Transnasal brain drug targeting could ensure better drug delivery to the brain through the olfactory pathway. Risperidone bioavailability is 66% in extensive metabolizers and 82% in slow metabolizers. The aim of this study is to investigate the ability of the nanovesicular spanlastics to effectively deliver risperidone through the nasal route to the brain and increase its bioavailability. Spanlastics formulae, composed of span and polyvinyl alcohol, were designed based on central composite statistical design. The planned formulae were prepared using ethanol injection method. The prepared formulae were characterized by testing their particle size, polydispersity index, zeta potential and encapsulation efficiency. The optimized formula having the lowest particle size, polydispersity index, the highest zeta potential and encapsulation efficiency was subjected to further investigations including characterization of its rheological properties, elasticity, transmission electron microscopy, in vitro diffusion, ex vivo permeation, histopathology and in vivo biodistribution. The optimized formula was composed of 5mg/mL span and 30mg/mL polyvinyl alcohol. It showed significantly higher transnasal permeation and better distribution to the brain, when compared to the used control regarding the brain targeting efficiency and the drug transport percentage (2.16 and 1.43 folds increase, respectively). The study introduced a successful and promising formula to directly and effectively carry the drug from nose to brain. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Chromium Stable Isotope Fractionation - An Indicator of Hexavalent Chromium Reduction.

    Science.gov (United States)

    Ellis, A.; Johnson, T. M.; Bullen, T. D.

    2001-12-01

    Chromium is a common anthropogenic contaminant in surface water and ground water, and is also of interest in oceanography. It is redox-active; the two common valences in natural waters are Cr(VI), which is highly soluble and toxic, and Cr(III), which is relatively insoluble. Redox reactions thus control Cr mobility in aqueous solutions, and reduction of Cr(VI) to Cr(III) is the most important reaction controlling attenuation of Cr in groundwater. Our results show that Cr(VI) reduction favors the lighter isotopes and leads to enrichment of heavier isotopes in the remaining Cr(VI). Cr isotope measurements thus show great promise as indicators of Cr(VI) reduction. We report here the first measurements of the magnitude of Cr isotope fractionation during Cr(VI) reduction and variations in δ 53Cr values obtained from three contaminated sites. Experiments were conducted to measure Cr isotope fractionation during Cr(VI) reduction by suspensions of magnetite and unamended sediments from a local pond, Urbana, IL and San Francisco Estuary near Martinez, CA. Suspensions were incubated anaerobically with constant shaking, and complete Cr(VI) reduction occurred within a few days. Cr(VI) from intermediate time points in the experiments was purified via ion exchange and 53Cr/52Cr ratios were measured via TIMS with a double isotope spike. The instantaneous per mil fractionation, ɛ , was calculated assuming a Rayleigh fractionation model. The ɛ for Cr(VI) reduction on magnetite surfaces yielded a fractionation of -3.5 ‰ . The ɛ values for the pond and estuary sediments were -3.5 ‰ and -3.3 ‰ respectively. The size of this Cr isotope fractionation is encouraging, as current precision is 0.2 \\permil. δ 53Cr values in dissolved Cr(VI) from three contaminated sites range from 1.1 ‰ to 5.8 ‰ , suggesting that Cr(VI) reduction has occurred and has induced isotopic fractionation in these settings. δ 53Cr values measured from Cr(VI) in plating baths show little or no

  15. Hexavalent Chromium IV-Free Primer Development

    Science.gov (United States)

    Alldredge, Michael J.; Buck, Amy L.

    2015-01-01

    Primer materials provide corrosion protection for metal parts as well as an increased adhesion between metallic substrates and thermal protection systems (TPSs). Current primers for use in cryogenic applications contain hexavalent chromium. This hexavalent chromium provides excellent corrosion protection even in a cryogenic environment, but it is a carcinogen that requires special equipment and waste control procedures to use. The hazardous nature of hexavalent chromium makes it an obsolescence risk in the future. This study included two phases of evaluation. Thirteen primers were initially identified as candidates and twelve of those primers were tested in phase 1. Four of the best performing candidates from phase 1 continued into phase 2 testing. Phase 1 testing consisted mostly of liquid constituent and physical property testing. Cryoflex and salt fog testing were included in phase 1 because of their importance to the overall success of a candidate material. Phase 2 consisted of physical, thermal, and mechanical properties for nominally processed and fabricated specimens.

  16. Recovery of Proteins and Chromium Complexes from Chromium – Containing Leather Waste (CCLW

    Directory of Open Access Journals (Sweden)

    B. Gutti

    2010-08-01

    Full Text Available Chromium – Containing Leather Waste (CCLW constitutes an environmental pollution problem to leather industries disposing the waste by landfill. The waste mainly consists of collagen and chromium III complexes. This work is a design of reactors to recover gelatin, polypeptides and chromium from CCLW. The results of the experiment shows that 68% of protein, based on dry weight of leather scraps, could be recovered. Three reactors with a total volume of 18 m3 was designed to handle 10,431 kg of waste generated from the tanning industries.

  17. REMOVAL OF CHROMIUM FROM AQUEOUS SOLUTION USING LOCALLY AVAILABLE INEXPENSIVE TARO AND WATER HYACINTH AS BIOSORBENT

    Directory of Open Access Journals (Sweden)

    Shahjalal Khandaker

    2016-04-01

    Full Text Available In this investigation, locally available and inexpensive Taro and Water Hyacinth were used as biosorbents to remove chromium from synthetic wastewater. The removal of this metal ion from water in the batch and column method have been studied and discussed. Adsorption kinetics and equilibrium isotherm studies were also carried out. The material exhibits good adsorption capacity and the data follow both Freundlich and Langmuir models. Scanning Electronic Microscopic image was also used to understand the surface characteristics of biosorbent before and after biosorption studies. Effects of various factors such as pH, adsorbent dose, adsorbate initial concentration, particle size etc. were analyzed. The initial concentrations of chromium were considered 5-30mgL-1 in batch method and only 4mgL-1 in column method. The maximum chromium adsorbed was 1.64 mgg-1 and 4.44 mgg-1 in Batch method and 1.15 mgg-1 and 0.75 mgg-1 in Column method. Batch and Column desorption and regeneration studies were conducted. Column desorption studies indicated that both of these biosorbents could be reused for removing heavy metals. Results of the laboratory experiments show that the performance of Taro and Water Hyacinth prove that they can effectively be used as low cost biosorbents for the removal of chromium from wastewater.KEYWORDS:   adsorption; chromium removal; Taro; water hyacinth; batch method; column studies

  18. Effect of nickel and chromium exposure on buccal cells of electroplaters.

    Science.gov (United States)

    Qayyum, Saba; Ara, Anjum; Usmani, Jawed Ahmad

    2012-02-01

    The electroplating industry commonly involves the use of nickel and chromium. An assessment of the genotoxic effects of these metals can be carried out by micronucleus (MN) test in buccal cells. Other nuclear anomalies (NA) observed in buccal cells viz., karyorrhexis, pyknosis and karyolysis are also the indicators of genotoxicity. The current study aims at determining the extent of genotoxic damage in relation to the duration of exposure to nickel and hexavalent chromium via micronuclei induction and other nuclear anomalies. The present investigation included 150 subjects of which 50 individuals with no history of nickel/chromium exposure (Group I) were taken as control, 50 electroplaters exposed to nickel and hexavalent chromium for duration of less than 10 years (Group II) and 50 electroplaters exposed for ≥10 years (Group III) were included. Slides of buccal cells were prepared and the frequency of MN (‰) and NA (‰) were calculated. ANOVA was applied to test significance. Results were considered significant at p exposure increased. Plasma nickel and chromium levels were also determined which showed a positive correlation with frequency MN and other nuclear abnormalities (p < 0.01).

  19. Analysis on the stability of chromium in mineral phases in stainless steel slag

    Science.gov (United States)

    Cao, Long-hu; Liu, Cheng-jun; Zhao, Qing; Jiang, Mao-fa

    2017-11-01

    Stainless steel slag from high alloy steel is hardly used in the construction industry. The chromium leaching in unstable phase is the limiting factor for the application in the slag. The aim of this study is to investigate the stability of mineral phases in stainless steel slag. In this work, the mineral phases were firstly confirmed through experimental results by SEM-EDS and XRD. Thermodynamic calculation and leaching test were adopted to characterize the theoretical stability of mineral phases in aqueous solution. The results showed that the main phases in the stainless steel slag were spinel, melilite [solid solution of gehlenite (Ca2Al2SiO7) and akermanite (Ca2MgSi2O7)], dicalcium silicate, merwinite and periclase phases. It can be concluded that the minerals behave differently when dissolving in aqueous solution and the dissolution of dicalcium silicate (Ca2SiO4), merwinite (Ca3MgSi2O8), akermanite (Ca2MgSi2O7) and periclase phase could be generally higher, especially at lower pH values. In addition, the solubility of chromium in the spinel phase is considered low. The leaching test demonstrated that the formation of spinel phase can limit the leaching of chromium and the chromium existing in the silicate and periclase phases can facilitate the chromium leaching.

  20. The determination of chromium in water samples by neutron activation analysis after preconcentration on activated carbon

    International Nuclear Information System (INIS)

    Sloot, H.A. van der

    1977-01-01

    A method is presented for the determination of chromium in sea- and fresh water. Chromium is concentrated on activated carbon from a neutral solution after a previous reduction of chromate with sodium sulfite at pH 1.5. The adsorption conditions, acidity, concentrations, amount of carbon, stirring-time, sample-volume, salinity, the influence of storage on the ratio of tervalent to hexavalent chromium, were investigated. The final determination of the total chromium content is performed by instrumental neutron-activation analysis. By preconcentration on activated carbon, a differentiation between tervalent and hexavalent chromium is possible. A separate determination of both species is not yet feasible due to the high carbon blank and to the necessity of measuring the adsorption percentage on carbon. The lower limit of determination, which depends on the value of the carbon blank, is 0.05 μg Cr/l with a precision of 20%. The determination is hampered by the considerable blank from the carbon. The use of activated carbon prepared from recrystallized sugar will probably improve the lower limit of determination and possibly allow the determination of chromate. (T.G.)

  1. Determination of chromium combined with DNA, RNA and proteins in chromium-rich brewer's yeast by NAA

    International Nuclear Information System (INIS)

    Ding, W.J.; Qian, Q.F.; Hou, X.L.; Feng, W.Y.; Chai, Z.F.

    2000-01-01

    The content of chromium in the DNA, RNA and protein fractions separated from chromium-rich and normal brewer's yeast was determined by neutron activation analysis (NAA). Our results show that the extracted relative amounts and concentrations of DNA, RNA and proteins have no significant difference for two types of yeast, but the chromium content in DNA, RNA and proteins fractions extracted from the chromium-rich yeast are substantially higher than those from the normal. In addition, the concentration of chromium in DNA is much higher than that in RNA and proteins. It is evident that the inorganic chromium compounds can enter the yeast cell during the yeast cultivation in the chromium-containing culture medium and are converted into organic chromium species, which are combined with DNA, RNA and proteins. (author)

  2. Native Chromium Resistant Staphylococci Species from a Fly Ash ...

    African Journals Online (AJOL)

    Sixty-six chromium-resistant Staphylococci species belonging to S. epidermidis, S. aureus, S. saprophyticus and S. arlettae were previously isolated from a chromium-polluted Fly ash (FA) dumping site in South Africa. However the genetic mechanisms responsible for chromium resistance were not known. Polymerase chain ...

  3. Quantitative determination of chromium in some vegetables in ...

    African Journals Online (AJOL)

    Chromium has been known to be a micronutrient for mammals for more than four decades. Deficiency in the body results to diabetes, infertility and cardiovascular diseases. However, progress in elucidating the role of chromium has proceeded slowly. Recent studies have shown a potential role of chromium in maintaining ...

  4. Assessment of the level of chromium species in the discharged ...

    African Journals Online (AJOL)

    The purpose of this study was to assess the level of chromium species in the discharged effluents of selected tanneries in the Amhara Region; Haik and Debre Berhan tanneries. The level of total chromium, and hexavalent chromium in the discharged effluent of the studied tanneries were determined using the ICP-OES, and ...

  5. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1015 Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide is a blue-green pigment obtained by calcining a...

  6. 21 CFR 73.2327 - Chromium oxide greens.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium oxide greens. 73.2327 Section 73.2327... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2327 Chromium oxide greens. (a) Identity and specifications. The color additive chromium oxide greens shall conform in identify and specifications to the...

  7. 21 CFR 73.1327 - Chromium oxide greens.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium oxide greens. 73.1327 Section 73.1327... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1327 Chromium oxide greens. (a) Identity. (1) The color additive chromium oxide greens is principally chromic sesquioxide (Cr2O3). (2) Color additive...

  8. 21 CFR 73.3111 - Chromium oxide greens.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium oxide greens. 73.3111 Section 73.3111... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3111 Chromium oxide greens. (a) Identity and specifications. The color additive chromium oxide greens (chromic oxide) (CAS Reg. No. 1308-38-9...

  9. 75 FR 67100 - Superalloy Degassed Chromium From Japan

    Science.gov (United States)

    2010-11-01

    ... Chromium From Japan AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the antidumping duty order on superalloy degassed chromium from Japan. SUMMARY... order on superalloy degassed chromium from Japan would be likely to lead to continuation or recurrence...

  10. 21 CFR 73.1326 - Chromium hydroxide green.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium hydroxide green. 73.1326 Section 73.1326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1326 Chromium hydroxide green. (a) Identity. (1) The color additive chromium hydroxide green is principally hydrated chromic sesquioxide (Cr2O3·XH2O...

  11. 21 CFR 73.2326 - Chromium hydroxide green.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium hydroxide green. 73.2326 Section 73.2326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2326 Chromium hydroxide green. (a) Identity and specifications.The color additive chromium hydroxide green shall conform in identity and specifications to the...

  12. Levels of Lead, Cadmium and Chromium in Oreochromis Niloticus ...

    African Journals Online (AJOL)

    Lead (Pb), Cadmium (Cd) and Chromium (Cr) levels in Oreochromis niloticus, aquatic plants, water and sawdust were collected and analyzed for Lead, Cadmium and Chromium using atomic absorption spectroscopy. Results obtained showed that sawdust had the highest Lead and Chromium contents of 32.0 + 0.99 μg/g ...

  13. Preparation of liposomal amiodarone and investigation of its cardiomyocyte-targeting ability in cardiac radiofrequency ablation rat model

    Directory of Open Access Journals (Sweden)

    Zhuge Y

    2016-05-01

    Full Text Available Ying Zhuge,1,* Zhi-Feng Zheng,1,* Mu-Qing Xie,2 Lin Li,2 Fang Wang,1 Feng Gao2,3 1Department of Cardiology, Shanghai First People’s Hospital of Nanjing Medical University, 2Department of Pharmaceutics, School of Pharmacy, 3Shanghai Key Laboratory of Functional Materials Chemistry, East China University of Science and Technology, Shanghai, People’s Republic of China*These authors contributed equally to this workAbstract: The objective of this study was to develop an amiodarone hydrochloride (ADHC-loaded liposome (ADHC-L formulation and investigate its potential for cardiomyocyte targeting after cardiac radiofrequency ablation (CA in vivo. The ADHC-L was prepared by thin-film method combined with ultrasonication and extrusion. The preparation process was optimized by Box–Behnken design with encapsulation efficiency as the main evaluation index. The optimum formulation was quantitatively obtained with a diameter of 99.9±0.4 nm, a zeta potential of 35.1±10.9 mV, and an encapsulation efficiency of 99.5%±13.3%. Transmission electron microscopy showed that the liposomes were spherical particles with integrated bilayers and well dispersed with high colloidal stability. Pharmacokinetic studies were investigated in rats after intravenous administration, which revealed that compared with free ADHC treatment, ADHC-L treatment showed a 5.1-fold increase in the area under the plasma drug concentration–time curve over a period of 24 hours (AUC0–24 h and an 8.5-fold increase in mean residence time, suggesting that ADHC-L could facilitate drug release in a more stable and sustained manner while increasing the circulation time of ADHC, especially in the blood. Biodistribution studies of ADHC-L demonstrated that ADHC concentration in the heart was 4.1 times higher after ADHC-L treatment in CA rat model compared with ADHC-L sham-operated treatment at 20 minutes postinjection. Fluorescence imaging studies further proved that the heart-targeting

  14. An experimental model to investigate the targeting accuracy of MR-guided focused ultrasound ablation in liver.

    Science.gov (United States)

    Petrusca, Lorena; Viallon, Magalie; Breguet, Romain; Terraz, Sylvain; Manasseh, Gibran; Auboiroux, Vincent; Goget, Thomas; Baboi, Loredana; Gross, Patrick; Sekins, K Michael; Becker, Christoph D; Salomir, Rares

    2014-01-16

    Magnetic Resonance-guided High Intensity Focused Ultrasound (MRgHIFU) is a hybrid technology that aims to offer non-invasive thermal ablation of targeted tumors or other pathological tissues. Acoustic aberrations and non-linear wave propagating effects may shift the focal point significantly away from the prescribed (or, theoretical) position. It is therefore mandatory to evaluate the spatial accuracy of ablation for a given HIFU protocol and/or device. We describe here a method for producing a user-defined ballistic target as an absolute reference marker for MRgHIFU ablations. The investigated method is based on trapping a mixture of MR contrast agent and histology stain using radiofrequency (RF) ablation causing cell death and coagulation. A dedicated RF-electrode was used for the marker fixation as follows: a RF coagulation (4 W, 15 seconds) and injection of the mixture followed by a second RF coagulation. As a result, the contrast agent/stain is encapsulated in the intercellular space. Ultrasonography imaging was performed during the procedure, while high resolution T1w 3D VIBE MR acquisition was used right after to identify the position of the ballistic marker and hence the target tissue. For some cases, after the marker fixation procedure, HIFU volumetric ablations were produced by a phased-array HIFU platform. First ex vivo experiments were followed by in vivo investigation on four rabbits in thigh muscle and six pigs in liver, with follow-up at Day 7. At the end of the procedure, no ultrasound indication of the marker's presence could be observed, while it was clearly visible under MR and could be conveniently used to prescribe the HIFU ablation, centered on the so-created target. The marker was identified at Day 7 after treatment, immediately after animal sacrifice, after 3 weeks of post-mortem formalin fixation and during histology analysis. Its size ranged between 2.5 and 4 mm. Experimental validation of this new ballistic marker method was performed for

  15. Dynamics of Hexavalent Chromium in Four Types of Aquaculture Ponds and Its Effects on the Morphology and Behavior of Cultured Clarias gariepinus (Burchell 1822).

    Science.gov (United States)

    Mustapha, Moshood Keke

    2017-04-01

    Hexavalent chromium is a bio accumulative toxic metal in water and fish. It enters aquaculture ponds mainly through anthropogenic sources. Hexavalent chromium concentrations and its effects on the morphology and behavior of Clarias gariepinus were investigated from four aquaculture ponds for 12 weeks. Chromium was measured using diphenyl carbohdrazide method; alkalinity and hardness were measured using colometric method and analyzed with Bench Photometer. Temperature and pH were measured using pH/EC/TDS/Temp combined tester. Temporal and spatial replications of samples were done with triplicates morphological and behavioural effects of the metal on fish were observed visually. Chromium ranged from no detection to 0.05 mg/L, alkalinity 105 to 245 mg/L, hardness 80 to 165 mg/L, pH 6.35 to 8.03 and temperature 29.1 to 35.9°C. Trend in the chromium concentrations in the ponds is natural > earthen > concrete > collapsible. There was a significant difference ( P < 0.05) in chromium, alkalinity, water hardness, pH and temperature among the four ponds. Significant positive correlation also existed between alkalinity, water hardness, pH, with chromium. Morphological and behavioural changes observed in the fish include irregular swimming, frequent coming to the surface, dark body colouration, mucous secretion on the body, erosion of gill epithelium, fin disintegration, abdominal distension and lethargy. High chromium concentration in natural pond was due to anthropogenic run-off of materials in to the pond. Acidic pH, low alkalinity, low water hardness also contributed to the high chromium concentration. Morphological and behavioural changes observed were attributed to the high concentrations, toxicity and bio accumulative effect of the metal. Toxicity of chromium to fish in aquaculture could threaten food security. Watershed best management practices and remediation could be adopted to reduce the effects of toxicity of chromium on pond water quality, fish flesh quality and

  16. High temperature oxidation of iron-chromium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelsen, Lars

    2003-06-15

    The high temperature oxidation of the ferritic alloy Fe78Cr22 has been investigated in the present work. The effect of small alloying additions of cerium and/or silicon was also investigated. The alloys were oxidized at 973, 1173 and 1373 K in either air or a hydrogen/argon mixture. The various reaction atmospheres contained between 0.02 and 50% water vapour. The oxide scales formed on the various alloys at 973 K consisted of thin chromia layers. The oxide scales grown on the alloys at 1173 K also consisted of a chromia layer. The microstructure of the chromia scales was found to depend on the reaction atmosphere. The chromia scales grown in hydrogen/argon atmospheres formed oxide whiskers and oxide ridges at the surface of the scales, while the chromia scales grown in air formed larger oxide grains near the surface. This difference in oxide microstructure was due to the vaporization of chromium species from the chromia scales grown in air. Two different growth mechanisms are proposed for the growth of oxide whiskers. The growth rate of the chromia scales was independent of the oxygen activity. This is explained by a growth mechanism of the chromia scales, where the growth is governed by the diffusion of interstitial chromium. The addition of silicon to the iron-chromium alloy resulted in the formation of silica particles beneath the chromia scale. The presence of silicon in the alloy was found to decrease the growth rate of the chromia scale. This is explained by a blocking mechanism, where the silica particles beneath the chromia scale partly block the outwards diffusion of chromium from the alloy to the chromia scale. The addition of cerium to the iron-chromium alloy improved the adhesion of the chromia scale to the alloy and decreased the growth rate of chromia. It was observed that the minimum concentration of cerium in the alloy should be 0.3 at.% in order to observe an effect of the cerium addition. The effect of cerium is explained by the &apos

  17. Microbeam x-ray absorption spectroscopy study of chromium in large-grain uranium dioxide fuel

    Science.gov (United States)

    Mieszczynski, C.; Kuri, G.; Bertsch, J.; Martin, M.; Borca, C. N.; Delafoy, Ch; Simoni, E.

    2014-09-01

    Synchrotron-based microprobe x-ray absorption spectroscopy (XAS) has been used to study the local atomic structure of chromium in chromia-doped uranium dioxide (UO2) grains. The specimens investigated were a commercial grade chromia-doped UO2 fresh fuel pellet, and materials from a spent fuel pellet of the same batch, irradiated with an average burnup of ~40 MW d kg-1. Uranium L3-edge and chromium K-edge XAS have been measured, and the structural environments of central uranium and chromium atoms have been elucidated. The Fourier transform of uranium L3-edge extended x-ray absorption fine structure shows two well-defined peaks of U-O and U-U bonds at average distances of 2.36 and 3.83 Å. Their coordination numbers are determined as 8 and 11, respectively. The chromium Fourier transform extended x-ray absorption fine structure of the pristine UO2 matrix shows similar structural features with the corresponding spectrum of the irradiated spent fuel, indicative of analogous chromium environments in the two samples studied. From the chromium XAS experimental data, detectable next neighbor atoms are oxygen and uranium of the cation-substituted UO2 lattice, and two distinct subshells of chromium and oxygen neighbors, possibly because of undissolved chromia particles present in the doped fuels. Curve-fitting analyses using theoretical amplitude and phase-shift functions of the closest Cr-O shell and calculations with ab initio computer code FEFF and atomic clusters generated from the chromium-dissolved UO2 structure have been carried out. There is a prominent reduction in the length of the adjacent Cr-O bond of about 0.3 Å in chromia-doped UO2 compared with the ideal U-O bond length in standard UO2 that would be expected because of the change in effective Coulomb interactions resulting from replacing U4+ with Cr3+ and their ionic size differences. The contraction of shortest Cr-U bond is ~0.1 Å relative to the U-U bond length in bulk UO2. The difference in the

  18. Electronic structure simulation of chromium aluminum oxynitride by discrete variational-X alpha method and X-ray photoelectron spectroscopy

    CERN Document Server

    Choi, Y; Lee, J D; Kim, E; No, K

    2002-01-01

    We use a first-principles discrete variational (DV)-X alpha method to investigate the electronic structure of chromium aluminum oxynitride. When nitrogen is substituted for oxygen in the Cr-Al-O system, the N2p level appears in the energy range between O2p and Cr3d levels. Consequently, the valence band of chromium aluminum oxynitride becomes broader and the band gap becomes smaller than that of chromium aluminum oxide, which is consistent with the photoelectron spectra for the valence band using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). We expect that this valence band structure of chromium aluminum oxynitride will modify the transmittance slope which is a requirement for photomask application.

  19. Synthesis of chromium and ferrochromium alloy in molten salts by the electro-reduction method

    Directory of Open Access Journals (Sweden)

    Ge X.

    2015-01-01

    Full Text Available In this work, we successfully applied the Fray-Farthing-Chen Cambridge electro-reduction process on the preparation of chromium from chromium oxide, and for the first time, the synthesis of ferrochromium alloy from chromium oxide and iron oxide mixture and the chromite ore in molten calcium chloride. The present work systematically investigated the influences of sintered temperature of the solid precursor, electrochemical potential, electrolysis temperature and time on the products by using a set of advanced characterization techniques, including XRD and SEM/EDS analyses. In particular, our results show that this process is energy-friendly and technically-feasible for the direct extraction of ferrochromium alloy from chromite ore. Our findings thus provide useful insights for designing a novel green process to produce ferrochromium alloy from low-grade chromite ore or stainless steel slag.

  20. Galvanic Interaction between Chalcopyrite and Pyrite with Low Alloy and High Carbon Chromium Steel Ball

    Directory of Open Access Journals (Sweden)

    Asghar Azizi

    2013-01-01

    Full Text Available This study was aimed to investigate the galvanic interaction between pyrite and chalcopyrite with two types of grinding media (low alloy and high carbon chromium steel ball in grinding of a porphyry copper sulphide ore. Results indicated that injection of different gases into mill altered the oxidation-reduction environment during grinding. High carbon chromium steel ball under nitrogen gas has the lowest galvanic current, and low alloy steel ball under oxygen gas had the highest galvanic current. Also, results showed that the media is anodic relative to pyrite and chalcopyrite, and therefore pyrite or chalcopyrite with a higher rest potential acted as the cathode, whilst the grinding media with a lower rest potential acted as the anode, when they are electrochemically contacted. It was also found that low alloy steel under oxygen produced the highest amount of EDTA extractable iron in the slurry, whilst high carbon chromium steel under nitrogen atmosphere led to the lowest amount.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-03-29

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

  2. Positron lifetime calculations of defects in chromium containing hydrogen or helium

    International Nuclear Information System (INIS)

    Troev, T.; Markovski, A.; Peneva, S.; Yoshiie, T.

    2006-01-01

    The characteristics of defects in chromium containing hydrogen or helium atoms have been investigated by positron lifetime quantum calculations. On the basis of calculated results, the behaviors of empty nano-voids and nano-voids with hydrogen or helium were discussed. It was found that hydrogen and helium in larger three-dimensional vacancy clusters change the annihilation characteristics dramatically. The hydrogen and helium atoms are trapped by lattice vacancies. Helium bound with vacancies can form larger size cluster in chromium. These results provide physical insight for positron interactions with defects in chromium and can be used for prediction of hydrogen or helium generation for the design of fission and fusion reactors. The positron lifetime calculations were performed by the standard DFT density functional theory method. The electron wave functions have been obtained in the local density approximation LDA to the DFT

  3. Effect of boron carbide on primary crystallization of chromium cast iron

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2008-04-01

    Full Text Available In the paper results of the influence of boron carbide (B4C as inoculant of abrasion-resisting chromium cast iron (about 2,8% carbon and 18% chromium on primary crystallization researches are presented. Boron carbide dispersion was introduced at the bottom of pouring ladle before tap of liquid cast iron. In this investigations were used three different quantities of inoculant in amounts 0,1%; 0,2% and 0,3% with relation to bath weight. It has been demonstrated that such small additions of boron carbide change primary crystallization parameters, particularly temperature characteristic of process, their time and kinetics.

  4. Adhesive wear of iron chromium nickel silicon manganese molybdenum niobium alloys with duplex structure

    International Nuclear Information System (INIS)

    Lugscheider, E.; Deppe, E.; Ambroziak, A.; Melzer, A.

    1991-01-01

    Iron nickel chromium manganese silicon and iron chromium nickel manganese silicon molybdenum niobium alloys have a so-called duplex structure in a wide concentration range. This causes an excellent resistance to wear superior in the case of adhesive stress with optimized concentrations of manganese, silicon, molybdenum and niobium. The materials can be used for welded armouring structures wherever cobalt and boron-containing alloy systems are not permissible, e.g. in nuclear science. Within the framework of pre-investigations for manufacturing of filling wire electrodes, cast test pieces were set up with duplex structure, and their wear behavior was examined. (orig.) [de

  5. Using the "target constituent removal combined with bioactivity assay" strategy to investigate the optimum arecoline content in charred areca nut.

    Science.gov (United States)

    Peng, Wei; Liu, Yu-Jie; Hu, Mei-Bian; Yan, Dan; Gao, Yong-Xiang; Wu, Chun-Jie

    2017-01-05

    Charred areca nut (CAN) is used to treat dyspepsia and abdominal distension in children. However, reports revealed that arecoline, the most important active constituent of CAN, possesses potential toxicities. This study was designed to investigate the optimum arecoline content in CAN, using the "target constituent removal combined with bioactivity assay" strategy. Based on PTLC method, we prepared CAN lacking all arecoline (WAC-100R) and a series of different ratios of arecoline-removed CAN samples (WAC-Rx). MTT and acute toxicity assays indicated that decreasing content by 50% decreased CAN toxicity significantly. Animal results revealed arecoline contents over 50% could guarantee the beneficial effects of CAN on gastrointestinal tract. Additionally, decreasing arecoline content in CAN by 50% decreased its pro-apoptotic effects significantly. Furthermore, decreasing 50% arecoline content in CAN down-regulated the expressions of Cleaved-Caspase-3, c-jun, c-fos, COX-2, PGE2, and IL-1α. Thus, our results revealed that CAN with 50% arecoline content (WAC-50R) has similar beneficial effects on the gastrointestinal tract to CAN, whereas its toxicity was decreased significantly. Collectively, our study suggested that the strategy of "target constituent removal combined with bioactivity assay" is a promising method to identify the optimum arecoline content in CAN, which is approximately 0.12%.

  6. Cysteine Specific Targeting of the Functionally Distinct Peroxiredoxin and Glutaredoxin Proteins by the Investigational Disulfide BNP7787

    Directory of Open Access Journals (Sweden)

    Aulma R. Parker

    2015-03-01

    Full Text Available Glutaredoxin (Grx, peroxiredoxin (Prx, and thioredoxin (Trx are redoxin family proteins that catalyze different types of chemical reactions that impact cell growth and survival through functionally distinct intracellular pathways. Much research is focused on understanding the roles of these redoxin proteins in the development and/or progression of human diseases. Grx and Prx are overexpressed in human cancers, including human lung cancers. BNP7787 is a novel investigational agent that has been evaluated in previous clinical studies, including non-small cell lung cancer (NSCLC studies. Herein, data from activity assays, mass spectrometry analyses, and X-ray crystallographic studies indicate that BNP7787 forms mixed disulfides with select cysteine residues on Grx and Prx and modulates their function. Studies of interactions between BNP7787 and Trx have been conducted and reported separately. Despite the fact that Trx, Grx, and Prx are functionally distinct proteins that impact oxidative stress, cell proliferation and disease processes through different intracellular pathways, BNP7787 can modify each protein and appears to modulate function through mechanisms that are unique to each target protein. Tumor cells are often genomically heterogeneous containing subpopulations of cancer cells that often express different tumor-promoting proteins or that have multiple dysregulated signaling pathways modulating cell proliferation and drug resistance. A multi-targeted agent that simultaneously modulates activity of proteins important in mediating cell proliferation by functionally distinct intracellular pathways could have many potentially useful therapeutic applications.

  7. Effect of carbon and silicon on nitrogen solubility in liquid chromium and iron-chromium alloys

    International Nuclear Information System (INIS)

    Khyakkinen, V.I.; Bezobrazov, S.V.

    1986-01-01

    The study is aimed at specifying the role of carbon and silicon in high-chromium melts nitridation processes. It is shown that in high-chromium melts of the Cr-Fe-C system the nitrogen solubility is reduced with the growth of carbon content and in the chromium concentration range of 70-100% at 1873 K and P N 2 =0.1 MPa it is described by the lg[%N] Cr-Fe-C =lg[%N] cr-fe -0.098[%C] equation. While decreasing the temperature the nitrogen solubility in alloys is increased. Silicon essentially decreases the nitrogen solubility in liquid chromium. For the 0-10% silicon concentration range the relation between the equilibrium content of nitrogen and silicon at 1873 K and P N 2 =0.1 MPa is described by the straight line equation [%N] Cr-Si =6.1-0.338 [%Si

  8. Physiochemical Influence of Soil Minerals on the Organic Reduction of Soil Chromium

    International Nuclear Information System (INIS)

    Njoku, P.C.; Nweze, C.A.

    2009-01-01

    The physiochemical influence of soil minerals (Bentonite, Kaolinite, Diatomite,Rutile and Ferrihydrite) on the organic reduction ofchromium (VI) has been investigated with Oxalic acid as the organic reductant. The effect of pH and particle sizes of the soil minerals were also investigated. Results showed that with 0.1mol/dm3 concentration of Oxalic acid, the concentration of chromium(VI) remaining was 0.28, 0.34,0.38, 0.46 and 0.52mg/kgfor Bentonite, Rutile, Diatomite, Kaolinite and Ferrihydrite respectively whereas at 0.5mol/dm3of oxalic acid, the concentration of chromium reduced to 0.20,0.26, 0.30, 0.38, and0.44mg/kg for Bentonite, Rutile, Diatomite, Kaolinite and Ferrihydrite. Increasedconcentration of oxalic acid increased the reduction of chromium(VI) to chromium(III). At pH 5.0, the concentration of chromium(VI)left was 0.28, 0.34, 0.38,0.46 and 0.52mg/kg forBentonite, Rutile, Diatomite, Kaolinite and Ferrihydrite while at pH 2.5, concentration was0.16, 0.22, 0.26, 0.34 and 0.43mg/kg respectively. At particle size of 47-42 microns, concentration of chromium(VI) was 0.28, 0.34,0.38, 0.46, 0.52mg/kg for the same order ofthe soil minerals. At micron sizes of33-29 and 28-25 ranges the concentration ofchromium(VI) left was 0.23, 0.29, 0.33,0.41 and 0.47mg/kg for both micron sizes and corresponding minerals as well. These results showed that above 33-29 micron sizes, the influence of particle size was negligible. (author)

  9. Metallic component with a chromium carbide base protective coating

    International Nuclear Information System (INIS)

    Wolfla, T.A.; Tucker, R.C. Jr.

    1976-01-01

    The invention concerns a coating system to protect metal components in sodium and helium cooled nuclear reactors. It includes a nickel or iron based alloy metal substrate, a first coat formed on the substrate and comprising chromium carbides and a binder selected among the chromium-nickel, chromium-cobalt, chromium-iron alloys and the super-alloys, the first coating being between 25 and 380 microns thick, and a surface coating comprising pure chromium carbides and being between 12.5 and 125 microns thick [fr

  10. Urinary levels of nickel and chromium associated with dental restoration by nickel-chromium based alloys.

    Science.gov (United States)

    Chen, Bo; Xia, Gang; Cao, Xin-Ming; Wang, Jue; Xu, Bi-Yao; Huang, Pu; Chen, Yue; Jiang, Qing-Wu

    2013-03-01

    This paper aims to investigate if the dental restoration of nickel-chromium based alloy (Ni-Cr) leads to the enhanced excretions of Ni and Cr in urine. Seven hundred and ninety-five patients in a dental hospital had single or multiple Ni-Cr alloy restoration recently and 198 controls were recruited to collect information on dental restoration by questionnaire and clinical examination. Urinary concentrations of Ni and Cr from each subject were measure by graphite furnace atomic absorption spectrometry. Compared to the control group, the urinary level of Ni was significantly higher in the patient group of dental alloys or a higher index of metal crown not covered with the porcelain. Urinary levels of Cr were significantly higher in the three patient groups of metal crown exposure index. Linear curve estimations showed better relationships between urinary Ni and Cr in patients within 6-month groups. Our data suggested significant increased excretions of urinary Ni and Cr after dental restoration. Potential short- and long-term effects of Ni-Cr alloy restoration need to be investigated.

  11. Experimental investigation of a moving averaging algorithm for motion perpendicular to the leaf travel direction in dynamic MLC target tracking

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jai-Woong; Sawant, Amit; Suh, Yelin; Cho, Byung-Chul; Suh, Tae-Suk; Keall, Paul [Department of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul, Korea 131-700 and Research Institute of Biomedical Engineering, Catholic University of Korea, Seoul, 131-700 (Korea, Republic of); Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States); Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States) and Department of Radiation Oncology, Asan Medical Center, Seoul, 138-736 (Korea, Republic of); Department of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul, 131-700 and Research Institute of Biomedical Engineering, Catholic University of Korea, Seoul, 131-700 (Korea, Republic of); Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States) and Radiation Physics Laboratory, Sydney Medical School, University of Sydney, 2006 (Australia)

    2011-07-15

    Purpose: In dynamic multileaf collimator (MLC) motion tracking with complex intensity-modulated radiation therapy (IMRT) fields, target motion perpendicular to the MLC leaf travel direction can cause beam holds, which increase beam delivery time by up to a factor of 4. As a means to balance delivery efficiency and accuracy, a moving average algorithm was incorporated into a dynamic MLC motion tracking system (i.e., moving average tracking) to account for target motion perpendicular to the MLC leaf travel direction. The experimental investigation of the moving average algorithm compared with real-time tracking and no compensation beam delivery is described. Methods: The properties of the moving average algorithm were measured and compared with those of real-time tracking (dynamic MLC motion tracking accounting for both target motion parallel and perpendicular to the leaf travel direction) and no compensation beam delivery. The algorithm was investigated using a synthetic motion trace with a baseline drift and four patient-measured 3D tumor motion traces representing regular and irregular motions with varying baseline drifts. Each motion trace was reproduced by a moving platform. The delivery efficiency, geometric accuracy, and dosimetric accuracy were evaluated for conformal, step-and-shoot IMRT, and dynamic sliding window IMRT treatment plans using the synthetic and patient motion traces. The dosimetric accuracy was quantified via a {gamma}-test with a 3%/3 mm criterion. Results: The delivery efficiency ranged from 89 to 100% for moving average tracking, 26%-100% for real-time tracking, and 100% (by definition) for no compensation. The root-mean-square geometric error ranged from 3.2 to 4.0 mm for moving average tracking, 0.7-1.1 mm for real-time tracking, and 3.7-7.2 mm for no compensation. The percentage of dosimetric points failing the {gamma}-test ranged from 4 to 30% for moving average tracking, 0%-23% for real-time tracking, and 10%-47% for no compensation

  12. Experimental investigation of a moving averaging algorithm for motion perpendicular to the leaf travel direction in dynamic MLC target tracking

    International Nuclear Information System (INIS)

    Yoon, Jai-Woong; Sawant, Amit; Suh, Yelin; Cho, Byung-Chul; Suh, Tae-Suk; Keall, Paul

    2011-01-01

    Purpose: In dynamic multileaf collimator (MLC) motion tracking with complex intensity-modulated radiation therapy (IMRT) fields, target motion perpendicular to the MLC leaf travel direction can cause beam holds, which increase beam delivery time by up to a factor of 4. As a means to balance delivery efficiency and accuracy, a moving average algorithm was incorporated into a dynamic MLC motion tracking system (i.e., moving average tracking) to account for target motion perpendicular to the MLC leaf travel direction. The experimental investigation of the moving average algorithm compared with real-time tracking and no compensation beam delivery is described. Methods: The properties of the moving average algorithm were measured and compared with those of real-time tracking (dynamic MLC motion tracking accounting for both target motion parallel and perpendicular to the leaf travel direction) and no compensation beam delivery. The algorithm was investigated using a synthetic motion trace with a baseline drift and four patient-measured 3D tumor motion traces representing regular and irregular motions with varying baseline drifts. Each motion trace was reproduced by a moving platform. The delivery efficiency, geometric accuracy, and dosimetric accuracy were evaluated for conformal, step-and-shoot IMRT, and dynamic sliding window IMRT treatment plans using the synthetic and patient motion traces. The dosimetric accuracy was quantified via a γ-test with a 3%/3 mm criterion. Results: The delivery efficiency ranged from 89 to 100% for moving average tracking, 26%-100% for real-time tracking, and 100% (by definition) for no compensation. The root-mean-square geometric error ranged from 3.2 to 4.0 mm for moving average tracking, 0.7-1.1 mm for real-time tracking, and 3.7-7.2 mm for no compensation. The percentage of dosimetric points failing the γ-test ranged from 4 to 30% for moving average tracking, 0%-23% for real-time tracking, and 10%-47% for no compensation. Conclusions

  13. Experimental investigation of a moving averaging algorithm for motion perpendicular to the leaf travel direction in dynamic MLC target tracking.

    Science.gov (United States)

    Yoon, Jai-Woong; Sawant, Amit; Suh, Yelin; Cho, Byung-Chul; Suh, Tae-Suk; Keall, Paul

    2011-07-01

    In dynamic multileaf collimator (MLC) motion tracking with complex intensity-modulated radiation therapy (IMRT) fields, target motion perpendicular to the MLC leaf travel direction can cause beam holds, which increase beam delivery time by up to a factor of 4. As a means to balance delivery efficiency and accuracy, a moving average algorithm was incorporated into a dynamic MLC motion tracking system (i.e., moving average tracking) to account for target motion perpendicular to the MLC leaf travel direction. The experimental investigation of the moving average algorithm compared with real-time tracking and no compensation beam delivery is described. The properties of the moving average algorithm were measured and compared with those of real-time tracking (dynamic MLC motion tracking accounting for both target motion parallel and perpendicular to the leaf travel direction) and no compensation beam delivery. The algorithm was investigated using a synthetic motion trace with a baseline drift and four patient-measured 3D tumor motion traces representing regular and irregular motions with varying baseline drifts. Each motion trace was reproduced by a moving platform. The delivery efficiency, geometric accuracy, and dosimetric accuracy were evaluated for conformal, step-and-shoot IMRT, and dynamic sliding window IMRT treatment plans using the synthetic and patient motion traces. The dosimetric accuracy was quantified via a tgamma-test with a 3%/3 mm criterion. The delivery efficiency ranged from 89 to 100% for moving average tracking, 26%-100% for real-time tracking, and 100% (by definition) for no compensation. The root-mean-square geometric error ranged from 3.2 to 4.0 mm for moving average tracking, 0.7-1.1 mm for real-time tracking, and 3.7-7.2 mm for no compensation. The percentage of dosimetric points failing the gamma-test ranged from 4 to 30% for moving average tracking, 0%-23% for real-time tracking, and 10%-47% for no compensation. The delivery efficiency of

  14. Method for welding chromium molybdenum steels

    Science.gov (United States)

    Sikka, Vinod K.

    1986-01-01

    Chromium-molybdenum steels exhibit a weakening after welding in an area adjacent to the weld. This invention is an improved method for welding to eliminate the weakness by subjecting normalized steel to a partial temper prior to welding and subsequently fully tempering the welded article for optimum strength and ductility.

  15. The fate of chromium during tropical weathering

    DEFF Research Database (Denmark)

    Berger, Alfons; Frei, Robert

    2014-01-01

    We performed a mineral, geochemical and Cr–Sr–Pb isotope study on a laterite profile developed on ca. 540 Ma old tonalitic bedrock in Madagascar with special emphasis on the behavior of chromium during tropical weathering. The observed strong depletions of Ca, Si, and P, and enrichment of Fe and Al...

  16. The electronic structure of antiferromagnetic chromium

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt

    1981-01-01

    The author has used the local spin density formalism to perform self-consistent calculations of the electronic structure of chromium in the non-magnetic and commensurate antiferromagnetic phases, as a function of the lattice parameter. A change of a few per cent in the atomic radius brings...

  17. Chromium Tolerance and Bioremoval by Cyanobacteria Isolated ...

    African Journals Online (AJOL)

    Two cyanobacterial species Nostoc calcicola HH-12 and Chroococcus minutus HH-11 isolated from a textile mill oxidation pond were examined individually and as consortium for their chromium(VI) tolerance and bioremoval from aqueous solutions. Both species were tolerant to the metal and showed significant increase ...

  18. REMOVAL OF HEXAVALENT CHROMIUM FROM AQUEOUS ...

    African Journals Online (AJOL)

    a

    In this study, removal of chromium(VI) from aqueous solutions by Palmyra palm fruit seed carbon. (PPFSC) and commercial ... have studied the feasibility of less expensive materials such as alginate beads [15], wheat straw. [16], carbon develop from ... Arecaceae) is a largely populated tree in south India. EXPERIMENTAL.

  19. An assessment of the environmental toxicity of hexavalent chromium in fish

    NARCIS (Netherlands)

    Putte, van der I.

    1981-01-01

    At present chromium is a common contaminant in surface waters in many countries. In water the metal may be present in the trivalent form (CrIII) or in the hexavalent form (CrVI), the latter of which is more toxic to aquatic organisms.
    The investigations presented in this thesis

  20. PARTITIONING OF THE REFRACTORY METALS, NICKEL AND CHROMIUM, IN COMBUSTION SYSTEMS

    Science.gov (United States)

    The partitioning of nickel (Ni) and Chromium (Cr) in combustion systems was investigated theoretically and experimentally. In comparison to other volatile and semi-volatile metals, both Ni and Cr are usually considered to be refractory (non-volatile). Theoretical predictions ba...

  1. Electron microscopic study on pyrolysis of CCA (chromium, copper and arsenic oxide)-treated wood

    NARCIS (Netherlands)

    Hata, T.; Bronsveld, P.M; Vystavel, T.; Kooi, B.J.; de Hosson, J.T.M.; Kakitani, T.; Otono, A.; Imamura, Y.

    The effectiveness of pyrolysis as a possible technique for disposing of CCA (chromium, copper and arsenic oxide)-treated wood was studied. A CCA-treated sample given an extra heat treatment at 450 degreesC for 10 min was thoroughly investigated in order to establish the details of the reaction in

  2. Chromium removal from electroplating wastewater by coir pith

    International Nuclear Information System (INIS)

    Suksabye, Parinda; Thiravetyan, Paitip; Nakbanpote, Woranan; Chayabutra, Supanee

    2007-01-01

    Coir pith is a by-product from padding used in mattress factories. It contains a high amount of lignin. Therefore, this study investigated the use of coir pith in the removal of hexavalent chromium from electroplating wastewater by varying the parameters, such as the system pH, contact time, adsorbent dosage, and temperature. The maximum removal (99.99%) was obtained at 2% (w/v) dosage, particle size -1 , system pH 2, and an equilibrium time of 18 h. The adsorption isotherm of coir pith fitted reasonably well with the Langmuir model. The maximum Cr(VI) adsorption capacity of coir pith at 15, 30, 45 and 60 deg. C was 138.04, 197.23, 262.89 and 317.65 mg Cr(VI) g -1 coir pith, respectively. Thermodynamic parameters indicated an endothermic process and the adsorption process was favored at high temperature. Desorption studies of Cr(VI) on coir pith and X-ray absorption near edge structure (XANES) suggested that most of the chromium bound on the coir pith was in Cr(III) form due to the fact that the toxic Cr(VI) adsorbed on the coir pith by electrostatic attraction was easily reduced to less toxic Cr(III). Fourier transform infrared (FT-IR) spectrometry analysis indicated that the carbonyl (C=O) groups and methoxy (O-CH 3 ) groups from the lignin structure in coir pith may be involved in the mechanism of chromium adsorption. The reduced Cr(III) on the coir pith surface may be bound with C=O groups and O-CH 3 groups through coordinate covalent bonding in which a lone pair of electrons in the oxygen atoms of the methoxy and carbonyl groups can be donated to form a shared bond with Cr(III)

  3. Permeation of chromium salts through human skin in vitro

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Fullerton, A; Avnstorp, C

    1992-01-01

    Chromium permeation studies were performed on full thickness human skin in diffusion cells. All samples were analysed for the total chromium content by graphite furnace Zeeman-corrected atomic absorption spectrometry. Some samples were analysed by an ion chromatographic method permitting the simu......Chromium permeation studies were performed on full thickness human skin in diffusion cells. All samples were analysed for the total chromium content by graphite furnace Zeeman-corrected atomic absorption spectrometry. Some samples were analysed by an ion chromatographic method permitting...... the simultaneous determination of Cr(VI) and Cr(III) as well. The amounts of chromium found in all skin layers were significantly higher when potassium dichromate was applied to the skin compared with chromium chloride or chromium nitrate. Chromium could only be detected in the recipient phase after application...... of the dichromate solution. Chromium skin levels increased with increasing concentrations of applied chromium salts up to 0.034 M Cr. The amount of chromium in recipient phase and skin layers increased with increasing pH when the applied solution contained potassium dichromate. This was ascribed to a decreased skin...

  4. The Chromium is an essential element in the human

    International Nuclear Information System (INIS)

    Alvarado Gamez, A.; Blanco Saenz, R.; Mora Morales, E.

    2002-01-01

    The Chromium is an essential element for human and animals, because it a preponderant function in the insulin metabolism as a glucose tolerance factor (GTF). The deficiency of chromium engenders a deterioration in the glucose metabolism due to bad efficiency of insulin. Because the importance of this element an exhaustive reference review was made and this presents some studies realized in laboratory animals and in human beings where it is prove with resuits the effect of chromium over the improvement of patients with non-insulin dependant diabetes. Three substances are presented as chromium active biological forms: a material rich in chromium known as glucose tolerance factor, chromium picolinate and a substance of low molecular weight LMWCr in its forms of apo and holo that contains chromium and it links the insulin receptor and improves its activity. Also this paper presents information about the condition of diabetes in Costa Rica. (Author) [es

  5. Extraction Of Chromium From Leather Chrome Shaving Dust.

    Directory of Open Access Journals (Sweden)

    Ashiqur Rahaman

    2015-08-01

    Full Text Available Leather processing involves transformation of putrescible animal hides and skin into non putrescible leather. Leather industry generates a huge amount of solid waste containing chromium. These solid wastes were disposed of through land filling which causes leaching out of in soil and water. Now a day increasing environmental legislations have encouraged tannery industry to develop a new technology. In this study we incinerated chrome shaving dust at 500oC to 7000C for chromium extraction. Various oxidizing acids with different concentration were used for chromium extraction. Extracted chromium was measured by Atomic Absorption Spectrometry. Recovery of chromium was in the range of 297 mgL to 222 mgL. Nitric acid extracted maximum amount of chromium while sulfuric acid extracted minimum amount of chromium.

  6. Investigating the Target Language Usage in and outside Business English Classrooms for Non-English Major Undergraduates at a Chinese University

    Science.gov (United States)

    Xie, Qing

    2017-01-01

    This article reports an investigative study on the target language use in and outside business English classrooms for non-English major undergraduates in a Chinese university context. The aims of the study are to identify the actual situation of target language use in business English teaching and to suggest ways for improvements. The study uses…

  7. Investigating the foil-generated deuteron beam interaction with a DT target in degenerate and classical plasma

    Science.gov (United States)

    Mehrangiz, M.; Ghasemizad, A.

    2017-06-01

    Deuteron fast ignition of a conically guided pre-compressed DT fuel is investigated. For this purpose, the acceleration of the deuterated thin foil by the intense laser beam is evaluated. The acceleration values and the number of foil-generated deuterons are calculated in terms of the laser pulse duration. Using the created deuterons as the fast ignitors, we investigate the fast ignition scheme by comparing fully degenerate, partial degenerate and classical types of DT plasma. The total energy gain of deuterons "beam fusion" is calculated to show the efficiency of beam reactions in increasing fusion rate. Besides, the stopping time and stopping range of incident deuterons are evaluated. Our numerical results indicate that degeneracy increases the beam-target collisions. Thus, it prepares the ignition situation sooner than the classical plasma. Moreover, the number of generated deuterons and their acceleration depend on the foil thickness and laser parameters. We show that when a 4ps laser with intensity of 10^{19} W/cm^2 focused onto a 20μm foil, 35× 10^{15} deuterons are generated. Moreover, under our analysis, in order to have a practicable fast ignition, 18% of the laser energy is necessary to convert into a deuteron driver.

  8. The hazard of chromium exposure to neonates in Guiyu of China

    Energy Technology Data Exchange (ETDEWEB)

    Li Yan; Xu Xijin; Liu Junxiao; Wu Kusheng; Gu Chengwu; Shao Guo; Chen Songjian; Chen Gangjian [Central Laboratory and the Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou (China); Huo Xia [Central Laboratory and the Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou (China)], E-mail: xhuo@stu.edu.cn

    2008-09-15

    Guiyu is one of the most heavily chromium-polluted areas in China due to the presence of numerous electronic waste (e-waste) recycling sites in the region. In this study, we investigate the effect of umbilical cord blood chromium levels (UCBCLs) on neonates from Guiyu and discuss chromium-induced DNA damage of cord blood lymphocyte. Umbilical cord blood samples were collected from neonates of Guiyu (in 2006, n = 100; in 2007, n = 100) and the neighboring town of Chaonan (in 2006, n = 52; in 2007, n = 50) that is associated with the fishery. UCBCLs of the neonates were determined by graphite atomizer absorption spectrophotometer. Comet experiment was used to examine lymphocyte DNA damage. Questionnaires to gauge chromium exposure were administered to the mothers of the neonates. The mean UCBCLs of neonates in the Guiyu group in 2006 and 2007 were 303.38 {mu}g/L and 99.90 {mu}g/L with median 93.89 {mu}g/L and 70.60 {mu}g/L, respectively. We observed significant differences between the results in UCBCLs of neonates in Guiyu and the control group (P < 0.01). There was no significant difference of UCBCLs in neonates between 2006 and 2007 in Guiyu (P > 0.05). Higher levels of chromium in neonates were found to correlate with their mothers' exposure to e-waste recycling. There were significant differences in terms of DNA damage between the Guiyu group and the control group (P < 0.05). There was a correlation between DNA damage and the UCBCLs of neonates (P < 0.05). There is conclusive evidence that high UCBCLs in neonates exists in e-waste recycling areas in Guiyu and that e-waste recycling activity poses serious environmental problems. Chromium pollution is threatening the health of neonates around the recycling sites.

  9. [The effect of hydrogen peroxide on the electrochemical corrosion properties and metal ions release of nickel-chromium dental alloys].

    Science.gov (United States)

    Wang, Jue; Qiao, Guang-yan

    2013-04-01

    To investigate the effect of hydrogen peroxide on the electrochemical corrosion and metal ions release of nickel-chromium dental alloys. The corrosion resistance of nickel-chromium dental alloys was compared by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve (PD) methods in artificial saliva after immersed in different concentrations of hydrogen peroxide for 112 h. The metal ions released from nickel-chromium dental alloys to the artificial saliva were detected after electrochemical measurements using inductively coupled plasma mass spectrometry (ICP-MS). The data was statistically analyzed by analysis of variance (ANOVA) using SPSS 13.0 software package. The electrochemical experiment showed that the sequence of polarization resistance in equivalent circuit (Rct), corrosion potential (Ecorr), pitting breakdown potential (Eb), and the difference between Ecorr and Eb representing the "pseudo-passivation" (δE) of nickel-chromium alloys in artificial saliva was 30% alloys to the artificial saliva, and the order of the concentrations of metal ions was 0% corrosion resistance of nickel-chromium dental alloys decrease after immersed in different concentrations of hydrogen peroxide for 112 h. Nickel-chromium dental alloys are more prone to corrosion in the artificial saliva with the concentration of hydrogen peroxide increased, and more metal ions are released in the artificial saliva.

  10. Concentrations of zinc and chromium in aquatic macrophytes from the sudbury and muskoka regions of Ontario, Canada.

    Science.gov (United States)

    Reimer, P; Duthie, H C

    1993-01-01

    Root and shoot samples of Eriocaulon septangulare, Nuphar variegatum, Nymphaea odorata and Pontederia cordata were collected from 15 lakes in central Ontario during the summer of 1988 to investigate possible relationships between zinc and chromium levels in aquatic macrophytes and water and sediment variables. Although concentrations of zinc and chromium differed greatly among the four species, both metals were consistently higher in Eriocaulon. Generally, root and rhizome tissue contained higher zinc and chromium than shoot tissues of the same species and site. Zinc concentrations (dry weight) ranged from 6.3 microg g(-1) in Nuphar shoots to 87.7 microg g(-1) in whole Eriocaulon. Chromium ranged from 0.23 microg g(-1) in Pontederia shoots to 23.9 microg g(-1) in whole Eriocaulon. No significant trends were detected throughout the growing season in macrophyte or sediment concentrations of either metal. Results of multiple linear regression analyses of several water quality and environmental variables on Eriocaulon indicated that sediment zinc was the best predictor of plant zinc, and sediment chromium and calcium were the best predictors of plant chromium.

  11. Biotransformation of chromium (VI) in liquid effluents by resistant bacteria isolated from the Matanza-Riachuelo basin, in Argentina.

    Science.gov (United States)

    González, Ana Julieta; Caimán, Carolina; Gorino, Natalia; Fortunato, María Susana; Radice, Marcela; Gómez, Carlos; Mujica, Carolina; Marquina, Lorena; Gallego, Alfredo; Korol, Sonia Edith

    2017-10-10

    The aims of this investigation were to evaluate the bacterial resistance to zinc, copper, chromium (VI) and lead in surface water streams from Buenos Aires, Argentina; to select a chromium-resistant strain able to remove the metal in batch process and to evaluate the potential of this strain to remove chromium (VI) in liquid effluents. Bacterial resistance to the metals was evaluated by determining the minimal inhibitory concentration. The kinetic of chromium (VI) removal by one of the resistant strains was studied in nutrient broth with 50 and 100 mg L -1 of the metal, as well as an effluent from an electroplating industry. High resistance to all the metals under study was observed in the bacterial communities of the Matanza-Riachuelo basin. A chromium-resistant strain was isolated and identified as Microbacterium sp. It was able to remove 50 and 100 mg L -1 of Cr (VI) in 36 and 66 h respectively, with efficiency higher than 99%. Experiments with liquid effluents showed the ability of the strain to transform 150 mg L -1 of the metal in 84 h, with efficiency higher than 99%. These results show the potential of this native strain for the treatment of liquid effluents that contain chromium (VI).

  12. Numerical Investigation of the Time Discretization Impact on the Accuracy of a Point Target Localization by UWB Radar

    Science.gov (United States)

    Buša, Ján; Kocur, Dušan; Švecová, Mária

    2018-02-01

    UWB radar technologies enable localization of moving persons (targets) situated behind nonmetallic obstacles. Under exact knowledge of the propagation times, from the transmitting to the receiving antennas, of the radar emitted electromagnetic wave (time of arrival, TOA), a highly accurate target localization can be achieved. Since TOA estimates only are available, their use for target localization may result in a sizeable target localization error. In this paper we study the influence of TOA quantization on the point target localization accuracy using numerical simulation methods.

  13. Response of the pearl oyster Pinctada margaritifera to cadmium and chromium: Identification of molecular biomarkers

    OpenAIRE

    Gueguen, Yannick; Saulnier, Denis; Santini, Adrien; Magre, Kevin; Garen, Pierre; Bernagout, Solene; Nohl, Marine; Bouisset, Patrick; Helme, Herehia; Planes, Serge; Le Moullac, Gilles

    2017-01-01

    This study was designed to identify in the pearl oyster Pinctada margaritifera, used as a bio-accumulator, molecular biomarkers for the presence of heavy metals in the lagoon environment. Pearl oysters were exposed to 2 concentrations (1 and 10 μg L− 1) of cadmium (Cd) and chromium (Cr) compared to a control. Twelve target genes encoding proteins potentially involved in the response to heavy metal contamination with antioxidant, detoxification or apoptosis activities were selected. P. margari...

  14. Experimental investigation of adiabatic compression and heating using collision of an MHD-driven jet with a gas target cloud for magnetized target fusion

    Science.gov (United States)

    Seo, Byonghoon; Li, Hui; Bellan, Paul

    2017-10-01

    We are studying magnetized target fusion using an experimental method where an imploding liner compressing a plasma is simulated by a high-speed MHD-driven plasma jet colliding with a gas target cloud. This has the advantage of being non-destructive so orders of magnitude more shots are possible. Since the actual density and temperature are much more modest than fusion-relevant values, the goal is to determine the scaling of the increase in density and temperature when an actual experimental plasma is adiabatically compressed. Two new-developed diagnostics are operating and providing data. The first new diagnostic is a fiber-coupled interferometer which measures line-integrated electron density not only as a function of time, but also as a function of position along the jet. The second new diagnostic is laser Thomson scattering which measures electron density and temperature at the location where the jet collides with the cloud. These diagnostics show that when the jet collides with a target cloud the jet slows down substantially and both the electron density and temperature increase. The experimental measurements are being compared with 3D MHD and hybrid kinetic numerical simulations that model the actual experimental geometry.

  15. Sorption of Chromium (VI Using Excess Municipal Sludge

    Directory of Open Access Journals (Sweden)

    Farzaneh Mohammadi

    2014-04-01

    Full Text Available Removing or decreasing hexavalent Chromium from wastewater to the permitted levels is important due to its non-biodegradation, bioaccumulation, cancer-causing and toxic effects. In this study, biosorption of Cr(VI from aqueous solutions by Excess Active Municipal Sludge was investigated as a function of initial Chromium (VI concentration (in the range of 5-90 mg/l, initial pH (in the range of 2-8, agitation speed (in the range of 50-200 rpm, adsorbent dosage (in the range of 2-10 g/l and agitation time (in the range of 5-480 min in a batch system. The optimum conditions were found by full factorial design approach. The results showed that the equilibrium time for adsorbent is 120 minutes. Also, sorption data have a good fitness by Freundlich isotherm model and adsorption kinetic is adopted with pseudo-second order model. In batch studies, at optimum condition (90 mg/l initial concentration, pH 2, agitation speed 200 rpm and adsorbent dosage 4 g/l, the adsorption performance was about 96%; the maximum adsorption capacity was calculated about 41.69 mg of Cr/g of adsorbent. Overall, it can be concluded that Excess Active Municipal Sludge, has a good performance as a biological, biodegradable, abundant and low-cost adsorbent for the removal of Cr (VI from aqueous solutions.

  16. Interpreting atom probe data from chromium oxide scales

    International Nuclear Information System (INIS)

    La Fontaine, Alexandre; Gault, Baptiste; Breen, Andrew; Stephenson, Leigh; Ceguerra, Anna V.; Yang, Limei; Dinh Nguyen, Thuan; Zhang, Jianqiang; Young, David J.; Cairney, Julie M.

    2015-01-01

    Picosecond-pulsed ultraviolet-laser (UV-355 nm) assisted atom probe tomography (APT) was used to analyze protective, thermally grown chromium oxides formed on stainless steel. The influence of analysis parameters on the thermal tail observed in the mass spectra and the chemical composition is investigated. A new parameter termed “laser sensitivity factor” is introduced in order to quantify the effect of laser energy on the extent of the thermal tail. This parameter is used to compare the effect of increasing laser energy on thermal tails in chromia and chromite samples. Also explored is the effect of increasing laser energy on the measured oxygen content and the effect of specimen base temperature and laser pulse frequency on the mass spectrum. Finally, we report a preliminary analysis of molecular ion dissociations in chromia. - Highlights: • Chromium oxide scales are analyzed by picosecond-pulsed ultraviolet-laser assisted atom probe tomography. • The influence of laser energy, pulse frequency and temperature on thermal tail and composition is reported. • “Laser sensitivity factor”, a new thermal tail quantification parameter was introduced. • Ions dissociations in chromia during the analysis are discussed.

  17. Interpreting atom probe data from chromium oxide scales

    Energy Technology Data Exchange (ETDEWEB)

    La Fontaine, Alexandre [School of Aerospace, Mechanical, Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Gault, Baptiste [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Breen, Andrew; Stephenson, Leigh; Ceguerra, Anna V.; Yang, Limei [School of Aerospace, Mechanical, Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Dinh Nguyen, Thuan; Zhang, Jianqiang; Young, David J. [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Cairney, Julie M., E-mail: julie.cairney@sydney.edu.au [School of Aerospace, Mechanical, Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia)

    2015-12-15

    Picosecond-pulsed ultraviolet-laser (UV-355 nm) assisted atom probe tomography (APT) was used to analyze protective, thermally grown chromium oxides formed on stainless steel. The influence of analysis parameters on the thermal tail observed in the mass spectra and the chemical composition is investigated. A new parameter termed “laser sensitivity factor” is introduced in order to quantify the effect of laser energy on the extent of the thermal tail. This parameter is used to compare the effect of increasing laser energy on thermal tails in chromia and chromite samples. Also explored is the effect of increasing laser energy on the measured oxygen content and the effect of specimen base temperature and laser pulse frequency on the mass spectrum. Finally, we report a preliminary analysis of molecular ion dissociations in chromia. - Highlights: • Chromium oxide scales are analyzed by picosecond-pulsed ultraviolet-laser assisted atom probe tomography. • The influence of laser energy, pulse frequency and temperature on thermal tail and composition is reported. • “Laser sensitivity factor”, a new thermal tail quantification parameter was introduced. • Ions dissociations in chromia during the analysis are discussed.

  18. 75 FR 65067 - National Emission Standards for Hazardous Air Pollutant Emissions: Hard and Decorative Chromium...

    Science.gov (United States)

    2010-10-21

    ... Air Pollutant Emissions: Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks... Decorative Chromium Electroplating and Chromium Anodizing Tanks; Group I Polymers and Resins; Marine Tank... Proposed Action NESHAP for: OECA contact \\1\\ OAQPS contact \\2\\ Hard and Decorative Chromium Scott Throwe...

  19. Experimental Investigation of Proton Induced Thermal Shocks and Magnetohydrodynamic Effects in Molten Metal Pion Production Targets for a Neutrino Factory

    CERN Document Server

    Schaffarzick, D

    2001-01-01

    Neutrinos are one of the basic subatomic particles among electrons, protons and many more, which build all matter. Neutrinos appear in three different types. Sources of neutrinos are the sun and nuclear power plants. But the type of neutrinos created there is not exactly known and the type changes between their creation to their detection, so only assumptions can be made. This change of type is called “neutrino oscillation”. In order to enable the nuclear physisists to find out more about the neutrinos and the neutrino oscillation, a neutrino factory will be built which will produce a high intensity neutrino beam with exactly known parameters like number of particles and type of neutrinos. This neutrino beam can then be used to investigate the properties of the neutrinos at near and far detectors. In cooperation with other laboratories CERN has started a study of some of the many technological challenges of a neutrino factory. A major issue of the facility is the pion production target where p...

  20. Spin-polarized scanning tunneling microscopy and spectroscopy study of chromium on a Cr(001) surface.

    Science.gov (United States)

    Lagoute, J; Kawahara, S L; Chacon, C; Repain, V; Girard, Y; Rousset, S

    2011-02-02

    Several tens of chromium layers were deposited at 250 °C on a Cr(001) surface and investigated by spin-polarized scanning tunneling microscopy (SP-STM), Auger electron spectroscopy (AES) and scanning tunneling spectroscopy (STS). Chromium is found to grow with a mound-like morphology resulting from the stacking of several monolayers which do not uniformly cover the whole surface of the substrate. The terminal plane consists of an irregular array of Cr islands with lateral sizes smaller than 20 × 20 nm(2). Combined AES and STS measurements reveal the presence of a significant amount of segregants prior to and after deposition. A detailed investigation of the surface shows that it consists of two types of patches. Thanks to STS measurements, the two types of area have been identified as being either chromium pure or segregant rich. SP-STM experiments have evidenced that the antiferromagnetic layer coupling remains in the chromium mounds after deposition and is not significantly affected by the presence of the segregants.

  1. Investigation on fabrication and positioning of cryogenic shell laser fusion targets. Annual report, October 1, 1977--November 30, 1978

    International Nuclear Information System (INIS)

    Kim, K.

    1978-01-01

    The research has been directed toward fabrication and positioning of cryogenic shell laser fusion targets, with particular emphasis on the development of a scheme which would allow for continuous fabrication, inspection, and delivery of the targets. Specifically, progress has been made in each of the following areas: (1) fabrication of a uniform layer of solid DT inside a glass microshell using a combination of helium gas jets and a heater wire; (2) levitation-freezing of a DT-filled glass microshell as a method for fabricating and positioning a cryogenic shell target; (3) a target fabrication system intended for continuous fabrication, inspection, and delivery of cryogenic targets; and (4) development of diagnostics for inspection, recording, and analysis of a solid DT layer inside a glass microshell, and for observing the parameters controlling the target freezing process

  2. Modelling small groundwater systems - the role of targeted field investigations and observational data in reducing model uncertainty

    Science.gov (United States)

    Abesser, Corinna; Hughes, Andrew; Boon, David

    2017-04-01

    Coastal dunes are delicate systems that are under threat from a variety of human and natural influences. Groundwater modelling can provide a better understanding of how these systems operate and can be a useful tool towards the effective management of a coastal dune system, e.g. through predicting impacts from climatic change, sea level rise and land use management. Because of their small size, typically 10 - 100 km2, models representing small dune aquifer systems are more sensitive to uncertainties in input data, model geometry and model parameterisation as well as to the availability of observational data. This study describes the development of a groundwater flow model for a small (8 km2) spit dune system, Braunton Burrows, on the Southwest coast of England, UK. The system has been extensively studied and its hydrology is thought to be well understood. However, model development revealed a high degree of uncertainty relating to model structure (definition of model boundary conditions) and parameterisation (e.g., transmissivity distributions within the model domain). An iterative approach was employed, integrating (1) sensitivity analyses, (2) targeted field investigations and (3) Monte Carlo simulations within a cycle of repeated interrogation of the model outputs, observed data and conceptual understanding. Assessment of "soft information" and targeted field investigations were an important part of this iterative modelling process. For example, a passive seismic survey (TROMINO®) provided valuable new data for the characterisation of concealed bedrock topography and thickness of superficial deposits. The data confirmed a generally inclined underlying wave cut rock shelf platform (as suggested by literature sources), revealed a buried valley, and led to a more detailed delineation of transmissivity zones within the model domain. Constructing models with increasingly more complex spatial distributions of transmissivity, resulted in considerable improvements in

  3. Citric-acid preacidification enhanced electrokinetic remediation for removal of chromium from chromium-residue-contaminated soil.

    Science.gov (United States)

    Meng, Fansheng; Xue, Hao; Wang, Yeyao; Zheng, Binghui; Wang, Juling

    2018-02-01

    Electrokinetic experiments were conducted on chromium-residue-contaminated soils collected from a chemical plant in China. Acidification-electrokinetic remediation technology was proposed in order to solve the problem of removing inefficient with ordinary electrokinetic. The results showed that electrokinetic remediation removal efficiency of chromium from chromium-contaminated soil was significantly enhanced with acidizing pretreatment. The total chromium [Cr(T)] and hexavalent chromium [Cr(VI)] removal rate of the group acidized by citric acid (0.9 mol/L) for 5 days was increased from 6.23% and 19.01% in the acid-free experiments to 26.97% and 77.66% in the acidification-treated experiments, respectively. In addition, part of chromium with the state of carbonate-combined will be converted into water-soluble state through acidification to improve the removal efficiency. Within the appropriate concentration range, the higher concentration of acid was, the more chromium was released. So the removal efficiency of chromium depended on the acid concentration. The citric acid is also a kind of complexing agent, which produced complexation with Cr that was released by the electrokinetic treatment and then enhanced the removal efficiency. The major speciation of chromium that was removed from soils by acidification-electrokinetics remediation was acid-soluble speciation, revivification speciation and oxidation speciation, which reduced biological availability of chromium.

  4. Health risk assessment of zinc, chromium, and nickel from cow meat consumption in an urban Nigerian population.

    Science.gov (United States)

    Ihedioha, Janefrances N; Okoye, Chukwuma O B; Onyechi, Uchenna A

    2014-10-01

    Meat consumption is increasingly becoming a larger part of diets worldwide. However, the bioaccumulation of toxic metals from anthropogenic pollution is a potential health risk to human health. To measure the daily intake of zinc, chromium, and nickel from cow meat consumption and assess the possible health risks in an urban population in Nigeria. Dried meat samples were digested with 3 : 2HNO3 : HClO4 v/v. Zinc, chromium, and nickel concentrations were determined with atomic absorption spectrophotometer. Daily intakes of meat were obtained using a food frequency questionnaire (FFQ). The estimated daily intakes (EDI) (μg/person/day) ranges were: zinc (10 496-13 459), chromium (310·90-393·73), and nickel (26·72-34·87). Estimated daily intake for zinc was 15-30% of provisional maximum tolerable daily intake (PMTDI) and for nickel it was 8-15% of tolerable daily intake (TDI). Chromium intakes were above recommended daily intake (RDI). Target hazard quotient (THQ) for nickel and zinc were within WHO/FAO limit. There was no evidence of possible health risk to consumers with regard to zinc and nickel. However, chromium intake should be of utmost concern, while disposal of tanning waste should be checked.

  5. Investigating the effect of tumor vascularization on magnetic targeting in vivo using retrospective design of experiment.

    Science.gov (United States)

    Mei, Kuo-Ching; Bai, Jie; Lorrio, Silvia; Wang, Julie Tzu-Wen; Al-Jamal, Khuloud T

    2016-11-01

    Nanocarriers take advantages of the enhanced permeability and retention (EPR) to accumulate passively in solid tumors. Magnetic targeting has shown to further enhance tumor accumulation in response to a magnetic field gradient. It is widely known that passive accumulation of nanocarriers varies hugely in tumor tissues of different tumor vascularization. It is hypothesized that magnetic targeting is likely to be influenced by such factors. In this work, magnetic targeting is assessed in a range of subcutaneously implanted murine tumors, namely, colon (CT26), breast (4T1), lung (Lewis lung carcinoma) cancer and melanoma (B16F10). Passively- and magnetically-driven tumor accumulation of the radiolabeled polymeric magnetic nanocapsules are assessed with gamma counting. The influence of tumor vasculature, namely, the tumor microvessel density, permeability and diameter on passive and magnetic tumor targeting is assessed with the aid of the retrospective design of experiment (DoE) approach. It is clear that the three tumor vascular parameters contribute greatly to both passive and magnetically targeted tumor accumulation but play different roles when nanocarriers are targeted to the tumor with different strategies. It is concluded that tumor permeability is a rate-limiting factor in both targeting modes. Diameter and microvessel density influence passive and magnetic tumor targeting, respectively. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  6. Determination of tracer quantities of chromium in uranium

    International Nuclear Information System (INIS)

    Huart, A.

    1959-01-01

    A method is described for the photometric determination of chromium in uranium by absorbency at 540 mμ of the Cr(VI) diphenylcarbazide combination. After attack by nitric acid, the solution is made perchloric, and the chromium oxidised at the boiling point by permanganate. Excess oxidant is removed by hydrochloric acid. Study of operating conditions resulted in a method with an accuracy of ± 0,5 ppm for 0,5 to 15 ppm chromium in the metal. (author) [fr

  7. Analysis of molybdenum, chromium, vanadium and iron by polarographic techniques

    International Nuclear Information System (INIS)

    Al-Zand, T.K.

    1986-01-01

    The application of direct current Tast polarograph, differential pulse polarography and phase-selective alternative current Tast polarography to the problem of determining molybdenum, chromium, vanadium and iron in various supporting electrolytes is reported. The effect of the supporting electrolyte on the wave/peak potential and sensitivity of the metal ion have been examined. The polarographic methods were applied for simultaneous determination of chromium (3)/chromium (6), vanadium (4), vanadium (5) and iron (2)/iron (3) in different supporting electrolytes

  8. Electrodeposition of chromium on nickel electrode modified with pyridine

    International Nuclear Information System (INIS)

    Khomchenko, I.G.; Zolotovitskaya, L.V.

    1995-01-01

    Organic substance adsorption layer effect on chromium electrodeposition on the surface of a nickel electrode is studied. Pyridine, possessing high chemical resistance to oxidation including such medium as chromium acid, is used as a modifying agent. Electrode modification does not lead to a change of polarization curve slope. E-lg i - curve slope changes in electrolyte with pyridine addition which may be linked with the change of chromium electrodeposition mechanism in the presence of pyridine addition in electrolyte. 6 refs.; 5 figs

  9. Chromium oxide catalysts in the dehydrogenation of alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Airaksinen, S.

    2005-07-01

    Light alkenes, such as propene and butenes, are important intermediates in the manufacture of fuel components and chemicals. The direct catalytic dehydrogenation of the corresponding alkanes is a selective way to produce these alkenes and is frequently carried out using chromia/alumina catalysts. The aim of this work was to obtain structure-activity information, which could be utilised in the optimisation of this catalytic system. The properties of chromia/alumina catalysts were investigated by advanced in situ and ex situ spectroscopic methods, and the activities were measured in the dehydrogenation of isobutane. The dehydrogenation activity of chromia/alumina was attributed to coordinatively unsaturated redox and non- redox Cr{sup 3+} ions at all chromium loadings. In addition, the oxygen ions in the catalyst appeared to participate in the reaction. The reduction of chromia/alumina resulted in formation of adsorbed surface species: hydroxyl groups bonded to chromia and alumina were formed in reduction by hydrogen and alkanes, and carbon- containing species in reduction by carbon monoxide and alkanes. Prereduction with hydrogen or carbon monoxide decreased the dehydrogenation activity. The effect by hydrogen was suggested to be related to the amount of OH/H species on the reduced surface affecting the number of coordinatively unsaturated chromium sites, and the effect by carbon monoxide to the formation of unselective chromium sites and carboncontaining species. The chromia/alumina catalysts were deactivated with time on stream and in cycles of (pre)reduction- dehydrogenation-regeneration. The deactivation with time on stream was caused mainly by coke formation. The nature of the coke species changed during dehydrogenation. Carboxylates and aliphatic hydrocarbon species formed at the beginning of the reaction and unsaturated/aromatic hydrocarbons and graphite- like species with increasing time on stream. The deactivation in several dehydrogenation- regeneration

  10. Laboratory Automatic Titration of Chromium Plating and Electropolishing Solutions

    National Research Council Canada - National Science Library

    Sopok, Samuel

    2001-01-01

    .... The analytical chemistry literature lacks an adequate automatic titration method for the monitoring of chromic acid in chromium plating solutions and the monitoring of phosphoric and sulfuric acids...

  11. Adsorption of basic chromium sulfate used in the tannery industries by calcined hydrotalcite

    International Nuclear Information System (INIS)

    Lopez M, B. E.; Rivera R, R.; Iturbe G, J. L.; Olguin G, M. T.

    2011-01-01

    The sorption behavior of the chemical species of Cr(III) from aqueous solutions by hydrotalcite calcined products was investigated considering the equilibrium ph (5.0 to 8.9) and the chromium concentration in aqueous solution (from 10.6 to 430.0 mmol/L) to obtain the corresponding isotherms. Each solution was prepared from basic Cr(III) sulphate which is a primary tanning agent used in the tannery industries. In this work no previous oxidation treatment was done to form Cr(vi) in order to remove the chromium from aqueous solutions by hydrotalcite. The amount of chromium in the remaining solutions after the sorption processes in a batch system by visible spectroscopy (Vis) was determined. The calcined hydrotalcite before and after the contact with the chromium(III) solutions by X-ray power diffraction, thermogravimetric analysis and Fourier transformed infrared spectroscopy, were characterized. The specific are by Brunauer, Emmett and Teller (Bet) method of each sample was also evaluated. It was found that under the experimental conditions of this work hydrolyzed species of Cr(III) are precipitated on the surface of the calcined hydrotalcite instead other adsorption mechanism, and the sulfate ions were the responsible to regenerated the crystalline structure of hydrotalcite, therefore the results are discussed in terms of both Cr(III) and sulfate chemical species. (Author)

  12. Adsorption of basic chromium sulfate used in the tannery industries by calcined hydrotalcite

    Energy Technology Data Exchange (ETDEWEB)

    Lopez M, B. E.; Rivera R, R.; Iturbe G, J. L.; Olguin G, M. T., E-mail: beatriz.lopez@inin.gob.mx [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2011-07-01

    The sorption behavior of the chemical species of Cr(III) from aqueous solutions by hydrotalcite calcined products was investigated considering the equilibrium ph (5.0 to 8.9) and the chromium concentration in aqueous solution (from 10.6 to 430.0 mmol/L) to obtain the corresponding isotherms. Each solution was prepared from basic Cr(III) sulphate which is a primary tanning agent used in the tannery industries. In this work no previous oxidation treatment was done to form Cr(vi) in order to remove the chromium from aqueous solutions by hydrotalcite. The amount of chromium in the remaining solutions after the sorption processes in a batch system by visible spectroscopy (Vis) was determined. The calcined hydrotalcite before and after the contact with the chromium(III) solutions by X-ray power diffraction, thermogravimetric analysis and Fourier transformed infrared spectroscopy, were characterized. The specific are by Brunauer, Emmett and Teller (Bet) method of each sample was also evaluated. It was found that under the experimental conditions of this work hydrolyzed species of Cr(III) are precipitated on the surface of the calcined hydrotalcite instead other adsorption mechanism, and the sulfate ions were the responsible to regenerated the crystalline structure of hydrotalcite, therefore the results are discussed in terms of both Cr(III) and sulfate chemical species. (Author)

  13. Experimental evaluation of chromium-carbide-based solid lubricant coatings for use to 760 C

    Science.gov (United States)

    Dellacorte, Christopher

    1987-01-01

    A research program is described which further developed and investigated chromium carbide based self-lubricating coatings for use to 760 C. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The three coating components were blended in powder form, applied to stainless steel substrates by plasma spraying and then diamond ground to the desired coating thickness. A variety of coating compositions was tested to determine the coating composition which gave optimum tribological results. Coatings were tested in air, helium, and hydrogen at temperatures from 25 to 760 C. Several counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications, such as piston ring/cylinder liner couples for Stirling engines. In general, silver and fluoride additions to chromium carbide reduced the friction coefficient and increased the wear resistance relative to the unmodified coating. The lubricant additives acted synergistically in reducing friction and wear.

  14. Preliminary assessment of modified borosilicate glasses for chromium and ruthenium immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Farid, Osama M. [Reactors Department, Nuclear Research Center, Atomic Energy Authority of Egypt, P.O. 13759, Inshas, Cairo (Egypt); Centre of Nuclear Engineering (CNE), Department of Materials, Imperial College London, London, SW7 2BP (United Kingdom); Abdel Rahman, R.O., E-mail: alaarehab@yahoo.com [Hot Laboratory Center, Atomic Energy Authority of Egypt, P.O. 13759, Inshas, Cairo (Egypt)

    2017-01-15

    The feasibility of using modified alkali borosilicate glasses for ruthenium and chromium immobilization is preliminary assessed by investigating the immobilization system structure under normal conditions. Within this context, reference alkali borosilicate, and simulated Magnox-modified glasses were prepared and studied. The results indicate that ruthenium is immobilized in the vitreous structure as encapsulated RuO{sub 2} crystallites that act as seeds for heterogeneous nucleation of other crystalline phases. The presence of Zn, as modifier, has contributed to chromium immobilization in zincochromite spinel structure, whereas Ca is accommodated in the vitreous structure. Immobilization performance was evaluated by conducting conservative static leach test and studying the leached glass. Leached glass morphology was altered, where near surface reference glass is leached over 400 nm and simulated Magnox-modified sample is altered over 300 nm. Normalized release rates are within normal range for borosilicate material. For simulated Magnox-modified sample, Ca and alkali structural element, i.e. Na and Li, are leached via ion-exchange reaction. The ion-exchanged fraction equals 1.06 × 10{sup −8} mol/m{sup 2} s and chromium has slightly lower normalized release rate value than ruthenium. - Highlights: • The presence of modifiers and waste oxides led to localized de-vitrification. • Ruthenium is encapsulated within the vitreous glass network as RuO{sub 2} crystals. • Chromium is immobilized within the zincochromite spinel structure. • Pitting and cracks induced by leaching did not affect the immobilization performance.

  15. The soda-ash roasting of chromite ore processing residue for the reclamation of chromium

    Science.gov (United States)

    Antony, M. P.; Tathavadkar, V. D.; Calvert, C. C.; Jha, A.

    2001-12-01

    Sodium chromate is produced via the soda-ash roasting of chromite ore with sodium carbonate. After the reaction, nearly 15 pct of the chromium oxide remains unreacted and ends up in the waste stream, for landfills. In recent years, the concern over environmental pollution from hexavalent chromium (Cr6+) from the waste residue has become a major problem for the chromium chemical industry. The main purpose of this investigation is to recover chromium oxide present in the waste residue as sodium chromate. Cr2O3 in the residue is distributed between the two spinel solid solutions, Mg(Al,Cr)2O4 and γ-Fe2O3. The residue from the sodium chromate production process was analyzed both physically and chemically. The compositions of the mineral phases were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). The influence of alkali addition on the overall reaction rate is examined. The kinetics of the chromium extraction reaction resulting from the residue of the soda-ash roasting process under an oxidizing atmosphere is also investigated. It is shown that the experimental results for the roasting reaction can be best described by the Ginstling and Brounshtein (GB) equation for diffusion-controlled kinetics. The apparent activation energy for the roasting reaction was calculated to be between 85 and 90 kJ·mol-1 in the temperature range 1223 to 1473 K. The kinetics of leaching of Cr3+ ions using the aqueous phase from the process residue is also studied by treating the waste into acid solutions with different concentrations.

  16. Influence of selected modifiers on crystallization curve of chromium cast iron

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2009-07-01

    Full Text Available In article was introduced the results of investigations of modified chromium cast iron crystallization process. It the cast iron about composition of basic elements C = 2,8 % and Cr = 18% was modified with five substances (boron carbide, ferrosilicon, ferrocalciumsilicon, ferroniobium and ferroniobium with ferrovanadium. Influence on course of primary and secondary crystallization process was observed. The investigations of crystallization was conducted DTA method in tester DTA - C.

  17. Formation and properties of chromium nitride coatings on martensitic steels

    International Nuclear Information System (INIS)

    Mendala, B.; Swadzba, L.; Hetmanczyk, M.

    1999-01-01

    In this paper the results of investigation of coatings obtained by ARC-PVD method on martensitic E1961 (13H12NWMFA) steel, which is used on compressor blades in the aircraft engines, were presented. The chemical composition of E1961 was given. The PVT-550 device was used for coating. The protective chromium nitride coatings were tested. The influence of ARC-PVD method parameters for example: bias, pressure and flow rate of reactive gases on the structure and properties of the CrN coatings in corrosion tests were investigated. Technical parameters of obtained CrN coatings were given. The phase analysis of chromium nitride coatings obtained with different technical parameters were tested. The results of phase analysis are given. The pitting corrosion resistance tests in 10% FeCl 3 solution was conducted. The corrosion rate for CrN coated samples were defined. It was found that 50 V and 100 V bias, about 0.5 and 0.7 Pa pressure and 140 sccm (standard cubic centimeter) flow rate of nitride during coating favour the CrN monophase structure while increasing bias to 150 V, decreasing the pressure to about 0.5 Pa and 0.3 Pa and increasing the flow rate of nitride to 160 - 180 sccm favour the CrN+Cr 2 N diphase structure. On the basis of corrosion investigations for CrN coatings obtained with different ARC-PVD parameters the best corrosion resistance in 10% FeCl 3 solution for CrN+Cr 2 N diphase structure was found. (author)

  18. Establishing human heart chromium, cobalt and vanadium concentrations by inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Day, Patrick L; Eckdahl, Steven J; Maleszewski, Joseph J; Wright, Thomas C; Murray, David L

    2017-05-01

    Chromium, cobalt, and vanadium are used in metallic joint prosthesis. Case studies have associated elevated heart tissue cobalt concentrations with myocardial injury. To document the long term heart metal ion concentrations, a validated inductively coupled plasma mass spectroscopy (ICP-MS) method was needed. The method utilized a closed-vessel microwave digestion system to digest the samples. An ICP-MS method utilizing Universal Cell Technology was used to determine our target analyte concentrations. Accuracy was verified using reference materials. Precision, sensitivity, recovery and linearity studies were performed. This method was used to establish a reference range for a non-implant containing cohort of 80 autopsy human heart tissues RESULTS: This method demonstrated an analytic measurement range of 0.5-100ng/mL for each element. Accuracy was within ±10% of target value for each element. Within-run precision for each element was below 20% CV. The chromium, vanadium and cobalt concentrations (mean±SD) were 0.1523±0.2157μg/g, 0.0094±0.0211μg/g and 0.1039±0.1305μg/g respectively in 80 non-implant containing human heart tissue samples. This method provides acceptable recovery of the chromium, cobalt and vanadium in heart tissue; allowing assessment of the effects of metallic joint prosthesis on myocardial health. Copyright © 2017 Elsevier GmbH. All rights reserved.

  19. Evaluation of polymorphonuclear leukocyte chemotaxis of adult and neonatal rhesus monkeys using 51-chromium labeling method

    International Nuclear Information System (INIS)

    Kinoshita, Yo; Masuda, Kiyokazu; Kobayashi, Yohnosuke

    1987-01-01

    Chemotaxis of polymorphonuclear leukocytes (PMN) from heparinized venous blood of 8 adult rhesus monkeys (Macaca Mulatta) and 13 rhesus monkey neonates within 48 hours of birth were evaluated by using 51-chromium labeling method. PMNs were prepared by Ficoll-Hypaque gradient and dextran sedimentation procedures and the final 51-chromium uptake was 3.21 ± 1.27 % to original count. PMN chemotaxis was succeeded by using two different chemotaxis filters (Nuclepore filter on top of Millipore filter) with incubation at 37 deg C for 90 min. The mean value of target: non target ratio (CPM in lower filter with chemoattractant/CPM in lower filter without chemoattractant) of 3.56 ± 2.49 from neonates showed no significant difference from that of 4.44 ± 1.24 from adults. Only about 30 % of neonates showed an impaired chemotaxis, but others showed similar chemotactic activity as adults. The results show that the 51-chromium labeling method is useful to assess neutrophil functions in rhesus monkey species and suggest that host defense mechanism of the rhesus monkey may differ from that of human in neonatal period. (author)

  20. Study on the properties of chromium residue-cement matrices (CRCM) and the influences of superplasticizers on chromium(VI)-immobilising capability of cement matrices.

    Science.gov (United States)

    Shi, Hui-Sheng; Kan, Li-Li

    2009-03-15

    The study of cementitious activity of chromium residue (CR) was carried out to formulate the properties of chromium residue-cement matrices (CRCM) by blending CR with Ordinary Portland Cement (OPC). The particle size distribution, microstructures of CR were investigated by some apparatuses, and physical properties, leaching behavior of hexavalent chromium [Cr(VI)] of CRCM were also determined by some experiments. Three types of commonly used superplasticizers (sulphonated acetone formaldehyde superplasticizer (J1), polycarboxylate-based superplasticizer (J2) and naphthalene superplasticizer (J3)) were chosen to investigate their influences on the physical properties and the Cr(VI)-immobilisation in the leachate of the CRCM hardened pastes. The results show that the CR has a certain cementitious activity. The incorporation of CR improves the pore size distribution of CRCM. The Cr(VI) concentrations in the leachate of CRCM significantly decrease by incorporation of J2. Among three superplasticizers, J2 achieves lowest Cr(VI) leaching ratio. Based on this study, it is likely to develop CR as a potential new additive used in cement-based materials.

  1. Utilization of Ion Chromatography and Statistics to Determine Important Acids in Chromium Plating and Electropolishing Solutions

    National Research Council Canada - National Science Library

    Sopok, Samuel

    1991-01-01

    Inadequate monitoring of sulfuric and chromic acids in chromium plating solutions and phosphoric and sulfluric acids in electropolishing solutions can cause serious problems for the chromium plating...

  2. Chromium and nickel mobilization from a contaminated soil using chelants

    International Nuclear Information System (INIS)

    Jean, Liliane; Bordas, Francois; Bollinger, Jean-Claude

    2007-01-01

    The mobilization of chromium and nickel from an industrial soil was investigated using two biodegradable chelants (citric acid and histidine), compared with a persistent one (ethylenediaminetetraacetic acid). Successive metal mobilizations were carried out in batch experiments. The main reactions involved were estimated by modeling the system with MINEQL+. For a single mobilization, citric acid was the most effective for Cr mobilization and EDTA for Ni. Their effectiveness could be explained by their ability to solubilize the mineral matrix and by the competition for the surfaces sites to desorb Cr(VI). Before and after the mobilizations, the distribution of metals was determined by a sequential extraction procedure. Only slight modifications were observed due to the low percentage of solubilized metal. A concentration of 0.05 mol L -1 (citric acid and EDTA) allows a good compromise between metal mobilization and preservation of the soil mineral integrity. - Chelant-induced dissolution of soil mineral matrix controls metal solubilization

  3. Chromium and nickel mobilization from a contaminated soil using chelants

    Energy Technology Data Exchange (ETDEWEB)

    Jean, Liliane [Laboratoire des Sciences de l' Eau et de l' Environnement, Universite de Limoges, 123 avenue Albert Thomas, 87060 Limoges (France); Bordas, Francois [Laboratoire des Sciences de l' Eau et de l' Environnement, Universite de Limoges, 123 avenue Albert Thomas, 87060 Limoges (France)]. E-mail: francois.bordas@unilim.fr; Bollinger, Jean-Claude [Laboratoire des Sciences de l' Eau et de l' Environnement, Universite de Limoges, 123 avenue Albert Thomas, 87060 Limoges (France)

    2007-06-15

    The mobilization of chromium and nickel from an industrial soil was investigated using two biodegradable chelants (citric acid and histidine), compared with a persistent one (ethylenediaminetetraacetic acid). Successive metal mobilizations were carried out in batch experiments. The main reactions involved were estimated by modeling the system with MINEQL+. For a single mobilization, citric acid was the most effective for Cr mobilization and EDTA for Ni. Their effectiveness could be explained by their ability to solubilize the mineral matrix and by the competition for the surfaces sites to desorb Cr(VI). Before and after the mobilizations, the distribution of metals was determined by a sequential extraction procedure. Only slight modifications were observed due to the low percentage of solubilized metal. A concentration of 0.05 mol L{sup -1} (citric acid and EDTA) allows a good compromise between metal mobilization and preservation of the soil mineral integrity. - Chelant-induced dissolution of soil mineral matrix controls metal solubilization.

  4. Interpreting atom probe data from chromium oxide scales.

    Science.gov (United States)

    La Fontaine, Alexandre; Gault, Baptiste; Breen, Andrew; Stephenson, Leigh; Ceguerra, Anna V; Yang, Limei; Nguyen, Thuan Dinh; Zhang, Jianqiang; Young, David J; Cairney, Julie M

    2015-12-01

    Picosecond-pulsed ultraviolet-laser (UV-355 nm) assisted atom probe tomography (APT) was used to analyze protective, thermally grown chromium oxides formed on stainless steel. The influence of analysis parameters on the thermal tail observed in the mass spectra and the chemical composition is investigated. A new parameter termed "laser sensitivity factor" is introduced in order to quantify the effect of laser energy on the extent of the thermal tail. This parameter is used to compare the effect of increasing laser energy on thermal tails in chromia and chromite samples. Also explored is the effect of increasing laser energy on the measured oxygen content and the effect of specimen base temperature and laser pulse frequency on the mass spectrum. Finally, we report a preliminary analysis of molecular ion dissociations in chromia. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Tumor targeting using {sup 67}Ga-DOTA-Bz-folate - investigations of methods to improve the tissue distribution of radiofolates

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Cristina, E-mail: cristina.mueller@psi.ch [Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen-PSI (Switzerland); Vlahov, Iontcho R.; Santhapuram, Hari Krishna R.; Leamon, Christopher P. [Endocyte Inc., West Lafayette, IN 47906 (United States); Schibli, Roger [Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen-PSI (Switzerland); Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich (Switzerland)

    2011-07-15

    Introduction: Use of folic acid radioconjugates for folate receptor (FR) targeting is a promising strategy for imaging purposes as well as for potential therapy of cancer and inflammatory diseases due to the frequent FR overexpression found on cancer cells and activated macrophages. Herein, we report on preclinical results using a novel DOTA-Bz-EDA-folate conjugate radiolabeled with [{sup 67}Ga]-gallium. Methods: DOTA-Bz-EDA-folate was prepared by conjugation of ethylenediamine-({gamma})-folate with 2-(p-isothiocyanobenzyl)-DOTA. Radiolabeling was carried out with {sup 67}GaCl{sub 3} according to standard procedures. Biodistribution studies of the tracer were performed in mice bearing FR-positive KB tumor xenografts. The effects on radiofolate biodistribution with coadministered renal uptake-blocking amino acids, diuretic agents, antifolates as well as different routes of administration were likewise investigated. Supportive imaging studies were performed using a small-animal single photon emission computed tomography (SPECT)/CT scanner. Results: {sup 67}Ga-DOTA-Bz-EDA-folate showed a high and specific accumulation in tumors (6.30%{+-}0.75% ID/g, 1 h pi and 6.08%{+-}0.89% ID/g, 4 h pi). Nonspecific radioactivity uptake in nontargeted tissues was negligible, but significant accumulation was found in FR-positive kidneys, which resulted in unfavorably low tumor-to-kidney ratios (<0.1). Coadministered amino acids or diuretics did not effectively reduce renal accumulation; in contrast, predosed pemetrexed did significantly reduce kidney uptake (<29% of control values). The SPECT/CT studies confirmed the excellent tumor-to-background contrast of {sup 67}Ga-radiofolate and the favorable reduction in kidney uptake (with improved imaging quality) resulting from pemetrexed administration. Conclusion: Conventional methods to reduce kidney uptake of radiofolates fail. However, the novel {sup 67}Ga-radiolabeled DOTA-Bz-EDA-folate can effectively be used to image FR

  6. Specification for corrosion-resisting chromium and chromium-nickel steel bare and composite metal cored and stranded arc welding electrodes and welding rods

    International Nuclear Information System (INIS)

    Anon.

    1983-01-01

    This specification prescribes requirements for corrosion or heat resisting chromium and chromium-nickel steel electrodes and welding rods. These electrodes and welding rods are normally used for arc welding and include those alloy steels designated as corrosion or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4.0 percent and nickel does not exceed 50.0 percent

  7. Investigation of superparamagnetism in pure and chromium substituted cobalt nanoferrite

    Energy Technology Data Exchange (ETDEWEB)

    Raghasudha, M., E-mail: raghasudha_m@yahoo.co.in [Department of Chemistry, University College of Science, Osmania University, Hyderabad 500007, Telangana (India); Ravinder, D. [Department of Physics, University College of Science, Osmania University, Hyderabad 500007, Telangana (India); Veerasomaiah, P. [Department of Chemistry, University College of Science, Osmania University, Hyderabad 500007, Telangana (India)

    2016-12-15

    Nanostructured magnetic materials with the chemical composition CoFe{sub 2}O{sub 4} and CoCr{sub 0.9}Fe{sub 1.1}O{sub 4} were synthesized through Citrate-gel chemical synthesis with a crystallite size of 6.5 nm and 10.7 nm respectively. Structural characterization of the samples was performed by X-ray diffraction analysis and magnetic properties were studied using Vibrating Sample Magnetometer (VSM). Magnetization measurements as a function of applied magnetic field ±10 T at various temperatures 5 K, 25 K, 310 K and 355 K were carried out. Field cooled (FC) and Zero field cooled (ZFC) magnetization measurements under a magnetic field of 100 Oe for temperature ranging from 5–400 K were studied. The blocking temperature (T{sub b}) for both the ferrites was observed to be around 355 K. Below blocking temperature they showed ferromagnetic behavior and above which they are superparamagnetic in nature that favors their application in the biomedical field. The substitution of paramagnetic Cr{sup 3+} ions for magnetic Fe{sup 3+} ion in cobalt ferrite has resulted in a decrease in magnetization and the coercivity of the samples. CoCr{sub 0.9}Fe{sub 1.1}O{sub 4} nanoferrites with observed low coercivity of 338 Oe make them desirable in high frequency transformers due to their very soft magnetic behavior. - Highlights: • Particle size of CoFe{sub 2}O{sub 4} and CoCr{sub 0.9}Fe{sub 1.1}O{sub 4} is 6.5 nm and 10.7 nm respectively. • At 5 K and 25 K the materials were ferromagnetic in nature with high coercivity. • Materials show superparamagnetic behavior above room temperature. • Blocking temperature is at around 355 K where coercivity and remanence are zero. • Materials are suitable for hyperthermia cancer therapy.

  8. Ultra low nanowear in novel chromium/amorphous chromium carbide nanocomposite films

    Science.gov (United States)

    Yate, Luis; Martínez-de-Olcoz, Leyre; Esteve, Joan; Lousa, Arturo

    2017-10-01

    In this work, we report the first observation of novel nanocomposite thin films consisting of nanocrystalline chromium embedded in an amorphous chromium carbide matrix (nc-Cr/a-CrC) with relatively high hardness (∼22,3 GPa) and ultra low nanowear. The films were deposited onto silicon substrates using a magnetic filtered cathodic arc deposition system at various negative bias voltages, from 50 to 450 V. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) suggested the co-existence of chromium and chromium carbide phases, while high resolution transmission electron microscopy (HRTEM) confirmed the presence of the nc-Cr/a-CrC structure. The friction coefficient measured with the ball-on disk technique and the nanowear results showed a strong correlation between the macro and nano-tribological properties of the samples. These novel nanocomposite films show promising properties as solid lubricant and wear resistant coatings with relatively high hardness, low friction coefficient and ultra low nanowear.

  9. Bioreduction of chromium (VI) to chromium (III) by a novel yeast ...

    African Journals Online (AJOL)

    Introduction of heavy metal compounds like chromium, lead, arsenic and mercury into the environment generally induces morphological and physiological changes in the microbial communities hence exerting a selective pressure on the microorganisms. Generally, sites which are contaminated with heavy metals are the ...

  10. Relative effects of chromium and niobium on microstructure and mechanical properties as a function of oxygen content in TiAl alloys

    International Nuclear Information System (INIS)

    Lamirand, M.; Bonnentien, J.-L.; Ferriere, G.; Guerin, S.; Chevalier, J.-P.

    2007-01-01

    The effects of 2 at.% chromium and niobium on microstructure and mechanical properties of Ti-48Al-x(Cr, Nb) have been investigated for alloys with different oxygen content, ranging from ultra-high purity to doped alloys. Chromium and niobium additions have significant effects for the high purity alloys, whereas for alloys containing oxygen, no significant modification is observed due to the strong stabilizing effect of oxygen on the lamellar microstructure

  11. Chromium-Makes stainless steel stainless

    Science.gov (United States)

    Kropschot, S.J.; Doebrich, Jeff

    2010-01-01

    Chromium, a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point, is a silvery white, hard, and bright metal plating on steel and other material. Commonly known as chrome, it is one of the most important and indispensable industrial metals because of its hardness and resistance to corrosion. But it is used for more than the production of stainless steel and nonferrous alloys; it is also used to create pigments and chemicals used to process leather.

  12. Advances In Hexavalent Chromium Removal At Hanford

    International Nuclear Information System (INIS)

    Neshem, D.O.; Riddelle, J.

    2012-01-01

    At the Hanford Site, chromium was used as a corrosion inhibitor in the reactor cooling water and was introduced into the groundwater as a result of planned and unplanned discharges from reactors during plutonium production since 1944. Beginning in 1995, groundwater treatment methods were evaluated leading to the use of pump and treat facilities with ion exchange using Dowex 21 K, a regenerable strong base anion exchange resin. This required regeneration of the resin, which is currently performed offsite. Resin was installed in a 4 vessel train, with resin removal required from the lead vessel approximately once a month. In 2007, there were 8 trains (32 vessels) in operation. In 2008, DOE recognized that regulatory agreements would require significant expansion in the groundwater chromium treatment capacity. Previous experience from one of the DOE project managers led to identification of a possible alternative resin, and the contractor was requested to evaluate alternative resins for both cost and programmatic risk reductions. Testing was performed onsite in 2009 and 2010, using a variety of potential resins in two separate facilities with groundwater from specific remediation sites to demonstrate resin performance in the specific groundwater chemistry at each site. The testing demonstrated that a weak base anion single-use resin, ResinTech SIR-700, was effective at removing chromium, had a significantly higher capacity, could be disposed of efficiently on site, and would eliminate the complexities and programmatic risks from sampling, packaging, transportation and return of resin for regeneration. This resin was installed in Hanford's newest groundwater treatment facility, called 100-DX, which began operations in November, 2010, and used in a sister facility, 100-HX, which started up in September of 2011. This increased chromium treatment capacity to 25 trains (100 vessels). The resin is also being tested in existing facilities that utilize Dowex 21 K for

  13. Chromium, Nickel and Zinc Induced Histopathological Alterations in ...

    African Journals Online (AJOL)

    Degenerative histopathalogical alterations were seen in liver due to chronic exposure of the fish, Labeo rohita to chlorides of chromium, nickel and zinc for 30 days. However, more severe degenerative changes were observed in case of zinc chloride exposed fish than nickel chloride and chromium chloride treated fishes, ...

  14. Optical emission from laser-produced chromium and magnesium

    Indian Academy of Sciences (India)

    Parametric study of optical emission from two successive laser pulses produced chromium and magnesium plasma is presented. The line emission from chromium and magnesium plasma showed an increase by more than six times for double laser pulse excitation than for single-pulse excitation. An optimum increase in ...

  15. Chromium, Nickel and Zinc Induced Histopathological Alterations in ...

    African Journals Online (AJOL)

    Michael Horsfall

    ABSTRACT: Degenerative histopathalogical alterations were seen in liver due to chronic exposure of the fish, Labeo rohita to chlorides of chromium, nickel and zinc for 30 days. However, more severe degenerative changes were observed in case of zinc chloride exposed fish than nickel chloride and chromium chloride ...

  16. Removal of chromium and lead from drill cuttings using activated ...

    African Journals Online (AJOL)

    Palm kernel shell and Palm kernel husk, two readily available agricultural waste products have been used as low-cost potential adsorbents to remove chromium and lead from drill cuttings. Batch adsorption studies were carried out as a function of parameters such as pH, contact time and carbon dosage. Chromium and ...

  17. Optical emission from laser-produced chromium and magnesium ...

    Indian Academy of Sciences (India)

    Abstract. Parametric study of optical emission from two successive laser pulses pro- duced chromium and magnesium plasma is presented. The line emission from chromium and magnesium plasma showed an increase by more than six times for double laser pulse excitation than for single-pulse excitation. An optimum ...

  18. Optical emission from laser-produced chromium and magnesium ...

    Indian Academy of Sciences (India)

    Parametric study of optical emission from two successive laser pulses produced chromium and magnesium plasma is presented. The line emission from chromium and magnesium plasma showed an increase by more than six times for double laser pulse excitation than for single-pulse excitation. An optimum increase in ...

  19. Effect of chromium toxicity on germination and early seedling growth ...

    African Journals Online (AJOL)

    USER

    2010-07-19

    Jul 19, 2010 ... This study was conducted to determine and compare the inhibitory effects of chromium on seed germination and early seedling growth of melon (Cucumis melo L.). Chromium applications were controls; 2.5, 5, 10, 25, 50, 75, 100, 200 and 300 mgl-1 Cr in germination stage, and controls; 2.5, 5, 10,. 20, 30 ...

  20. remediation potential of Eichornia sp in conjunction with chromium

    African Journals Online (AJOL)

    Purpose: Evaluation of Cr (VI) removal by indigenous chromium resistant bacterial strains alone and in ... Chromium (Cr) is one of the toxic heavy metals ... membranes, ion exchange resins and reverse osmosis [3]. These expensive methodologies generate toxic by-products, so ecologically cost effective methods are ...

  1. Structure and morphology studies of chromium film at elevated ...

    Indian Academy of Sciences (India)

    Abstract. This paper presents the after shock heated structural and morphological studies of chromium film coated on hypersonic test model as a passive drag reduction element. The structural changes and the composition of phases of chromium due to shock heating (2850 K) are characterized using X-ray diffraction studies ...

  2. Optimization of chromium biosorption in aqueous solution by marine ...

    African Journals Online (AJOL)

    Optimization of a chromium biosorption process was performed by varying three independent variables pH (0.5 to 3.5), initial chromium ion concentration (10 to 30 mg/L), and Yarrowia lipolytica dosage (2 to 4 g/L) using a Doehlert experimental design (DD) involving response surface methodology (RSM). For the maximum ...

  3. Serum chromium concentrations in type 2 diabetic patients attending ...

    African Journals Online (AJOL)

    A highly refined diet that contains too few micronutrients has been recognized as the dominant factor in the rising incidence of diabetes and other insulin related conditions. Among the missing micronutrients, chromium has the greatest impact on insulin response. The objective of this study was to determine serum chromium ...

  4. Effects of chromium uptake on the growth characteristics of ...

    African Journals Online (AJOL)

    There were positive correlations between the concentration of chromium in the culture media and the amounts of the metal accumulated in the tissues of E. crassipes at any ... Plant growth analysis techniques were applied to assess the effects of chromium on the growth characteristics of the treated E. crassipes plants.

  5. induced Oxidation of Chromium(iii) by Peroxodisulphate

    African Journals Online (AJOL)

    plating, production of paints and pigments and paper and pulp production. The chemistry of chromium tailings from these industries in the environment is rather complex and not fully quantified.2,3. It is estimated that South Africa holds about 72% of the world's chromium reserves and is currently one of the largest chromate.

  6. Bioremediation of chromium in tannery effluent by microbial consortia

    African Journals Online (AJOL)

    USER

    2010-05-24

    May 24, 2010 ... Chromium is the most toxic and common among the heavy metal pollutants of industrial effluents. In the present work the chromium ... Heavy metals are ubiquitous and persistent environmen- tal pollutants that are introduced .... of other heavy metals like uranium in its cells might also match with its tendency.

  7. EFFECTS OF HIGHER LEVELS OF CHROMIUM AND COPPER ON SOME HAEMATOLOGICAL PARAMETERS AND SERUM PROTEINS IN BROILERS

    Directory of Open Access Journals (Sweden)

    M. Tariq Javed, F, Ahmad. N, Z, Rafique1 and M, Bashir

    2003-01-01

    Full Text Available Effects of higher levels of chromium alone and in combination with copper were investigated in broiler chicks divided into seven equal groups viz. A, B, C, D, E, F and G. Group G served as control receiving no treatment. Groups A, B and F received chromium chloride at the rate of 2 g/kg and nicotinic acid 150 mg/kg feed while C, D and F received chromium chloride 8 g/kg and nicotinic acid 150mg/kg. Broilers of groups A and C received copper sulfate at the rate of 200 mg/kg while groups Band D 400 mg/kg feed. Haematological parameters studied revealed non-significant difference between treatment groups and control in haemoglobin concentration and total erythrocyte counts. However, only at 4th week, lower PCV was observed in birds fed higher levels of chromium chloride alone. Increase in TLC was observed in birds fed low chromium alone or' with low levels of copper. Results of serum proteins including total protein, albumin and globulin during first three weeks showed significantly or relatively lower values in treatment groups than control. Serum globulins generally revealed non-significant difference between treatment groups and control.

  8. Liquid-liquid extraction of chromium (VI) from sulfuric acid solutions using tri-n-dodecylamine/kerosene

    International Nuclear Information System (INIS)

    Stas, J.

    2008-01-01

    Extraction of chromium (VI) from sulfuric acid solutions with tri-n-dodecylamine containing octanol-1 as a modifier in kerosene was investigated. All parameters influencing the extraction of chromium (VI) (time of agitation, concentrations of chromium (VI), sulfuric acid, tri-n-dodecylamine and temperature) were studied. Forst of all, tri-n-dodecylamine reacts with sulfuric acid to form tri-n-dodecylamine sulfate and bisulfate salts, then, dichromate ions is extracted by amine bisulfate. The mathematical treatment of the obtained date enabled us to calculate the formation of equilibrium constant of (TDAH) 2 SO 4 TDAHHSO 4 and (TDAH) 2 Cγ 2 O 7 at 25 Centigrade and have been found to be K 1 =10 9.642 (14/mol 4 ), K 2 = 10 -0.899 (L/mol) and K ex 10 10.55 respectively. Stripping of more than 99% of chromium (VI) from the organic phase of tri-n-dodecylamine/kerosene can be easily achieved in two stages using 0.05 M sodium carbonate solution. The synergistic effect of tri-n-butylphosphate and tri-n-octylphosphine oxide on the extraction of chromium (VI) were also studied. (author)

  9. Effect of Peroral Administration of Chromium on Insulin Signaling Pathway in Skeletal Muscle Tissue of Holstein Calves.

    Science.gov (United States)

    Jovanović, Ljubomir; Pantelić, Marija; Prodanović, Radiša; Vujanac, Ivan; Đurić, Miloje; Tepavčević, Snežana; Vranješ-Đurić, Sanja; Korićanac, Goran; Kirovski, Danijela

    2017-12-01

    The objective of this study was to investigate the effects of peroral administration of chromium-enriched yeast on glucose tolerance in Holstein calves, assessed by insulin signaling pathway molecule determination and intravenous glucose tolerance test (IVGTT). Twenty-four Holstein calves, aged 1 month, were chosen for the study and divided into two groups: the PoCr group (n = 12) that perorally received 0.04 mg of Cr/kg of body mass daily, for 70 days, and the NCr group (n = 12) that received no chromium supplementation. Skeletal tissue samples from each calf were obtained on day 0 and day 70 of the experiment. Chromium supplementation increased protein content of the insulin β-subunit receptor, phosphorylation of insulin receptor substrate 1 at Tyrosine 632, phosphorylation of Akt at Serine 473, glucose transporter-4, and AMP-activated protein kinase in skeletal muscle tissue, while phosphorylation of insulin receptor substrate 1 at Serine 307 was not affected by chromium treatment. Results obtained during IVGTT, which was conducted on days 0, 30, 50, and 70, suggested an increased insulin sensitivity and, consequently, a better utilization of glucose in the PoCr group. Lower basal concentrations of glucose and insulin in the PoCr group on days 30 and 70 were also obtained. Our results indicate that chromium supplementation improves glucose utilization in calves by enhancing insulin intracellular signaling in the skeletal muscle tissue.

  10. New Evidence against Chromium as an Essential Trace Element.

    Science.gov (United States)

    Vincent, John B

    2017-12-01

    Nearly 60 y ago, chromium, as the trivalent ion, was proposed to be an essential element, but the results of new studies indicate that chromium currently can only be considered pharmacologically active and not an essential element. Regardless, articles still continue to appear in the literature claiming chromium is an essential element. Chromium has been marketed as an agent to reduce body mass and develop muscle; however, such marketing claims are no longer allowed in the United States because these claims, similar to claims of essential status, are not supported by experiments. Trivalent chromium has also been proposed as a therapeutic agent to increase insulin sensitivity and affect lipid metabolism. Although effective in certain rodent models, beneficial effects in humans have not been unequivocally established. Molecular mechanisms have been proposed for the beneficial effects but have not been definitively shown to occur in animals. © 2017 American Society for Nutrition.

  11. Interaction of chromium(III) or chromium(VI) with catalase and its effect on the structure and function of catalase: An in vitro study.

    Science.gov (United States)

    Chen, Linfeng; Zhang, Jing; Zhu, Yaxian; Zhang, Yong

    2018-04-01

    Heavy metal chromium (Cr) poses a severe health risk to humans via food chain contamination. In this study, the interactions of either trivalent chromium (Cr(III)) or hexavalent chromium (Cr(VI)) with catalase (CAT) were investigated via multi-spectroscopic studies and computational simulations. The fluorescence analysis showed that Cr(III) and Cr(VI) quenched the fluorescence of CAT through a dynamic and a static quenching mechanism, respectively. The binding constant of Cr(VI) with CAT was 3.44×10 4 lmol -1 at 298K. Other detailed binding characterizations of the Cr(VI)-CAT complex were also obtained using spectra analysis and molecular docking. Synchronous fluorescence, UV-vis and circular dichroism (CD) spectral studies showed that either Cr(III) or Cr(VI) induced conformational changes of CAT, but the degree of influence was different. The response of CAT activity to Cr(III) or Cr(VI) was found to be variable depending on their valence states and concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Phosphate solubilization and chromium (VI) remediation potential of Klebsiella sp. strain CPSB4 isolated from the chromium contaminated agricultural soil.

    Science.gov (United States)

    Gupta, Pratishtha; Kumar, Vipin; Usmani, Zeba; Rani, Rupa; Chandra, Avantika

    2018-02-01

    In this study, an effort was made to identify an efficient phosphate solubilizing bacterial strain from chromium contaminated agricultural soils. Based on the formation of a solubilized halo around the colonies on Pikovskaya's agar amended with chromium (VI), 10 strains were initially screened out. Out of 10, strain CPSB4, which showed significantly high solubilization zone at different chromium concentrations, was selected for further study. The strain CPSB4 showed significant plant growth promotion traits with chromium (VI) stress under in-vitro conditions in broth. The plant growth promotion activities of the strain decreased regularly, but were not completely lost with the increase in concentration of chromium up to 200 mg L -1 . On subjected to FT-IR analysis, the presence of the functional group, indicating the organic acid aiding in phosphate solubilization was identified. At an optimal temperature of 30  ° C and pH 7.0, the strain showed around 93% chromium (VI) reduction under in-vitro conditions in broth study. In soil condition, the maximum chromium (VI) reduction obtained was 95% under in-vitro conditions. The strain CPSB4 was identified as Klebsiella sp. on the basis of morphological, biochemical and 16S rRNA gene sequencing. This study shows that the diverse role of the bacterial strain CPSB4 would be useful in the chromium contaminated soil as a good bioremediation and plant growth promoting agent as well. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. High-strength chromium--molybdenum rails

    International Nuclear Information System (INIS)

    Smith, Y.E.; Sawhill, J.M. Jr.; Cias, W.W.; Eldis, G.T.

    1976-01-01

    A laboratory study was conducted with the aim of developing an as-rolled rail of over 100 ksi (689 N/mm 2 ) yield strength. A series of compositions providing both pearlitic and bainitic microstructures was evaluated. A fine pearlitic structure was developed in a 0.73 percent C -- 0.83 percent Mn -- 0.16 percent Si -- 0.75 percent Cr -- 0.21 percent Mo steel by simulating the mill cooling rate of 132-lb/yd (65.5-kg/m) rail. Two 100-ton commercial heats were made of this approximate composition and processed into 132-lb/yd (65.5-kg/m) rail. Samples tested in the laboratory ranged from 109 to 125 ksi (750 to 860 N/mm 2 ) in yield strength. The chromium-molybdenum rails also exhibited excellent fracture toughness and fatigue properties. Sections of the rail were joined by both flash-butt welding and thermite welding. The hardness peaks produced in the flash-butt welds could be reduced by applying either a postweld current or an induction heating cycle. The high-strength chromium-molybdenum rails have been in service for over eight months in curved sections of an ore railway that carries over 55 million gross long tons per year. 7 tables, 18 figs

  14. Chromium(VI) bioremediation by probiotics.

    Science.gov (United States)

    Younan, Soraia; Sakita, Gabriel Z; Albuquerque, Talita R; Keller, Rogéria; Bremer-Neto, Hermann

    2016-09-01

    Chromium is a common mineral in the earth's crust and can be released into the environment from anthropogenic sources. Intake of hexavalent chromium (Cr(VI)) through drinking water and food causes toxic effects, leading to serious diseases, and is a commonly reported environmental problem. Microorganisms can mitigate or prevent the toxic effects caused by heavy metals in addition to having effective resistance mechanisms to prevent cell damage and bind to these metals, sequestering them from the cell surface and removing them from the body. Species of Lactobacillus, Streptococcus, Bacillus and Bifidobacterium present in the human mouth and gut and in fermented foods have the ability to bind and detoxify some of these substances. This review address the primary topics related to Cr(VI) poisoning in animals and humans and the use of probiotics as a way to mitigate or prevent the toxic effects caused by Cr(VI). Further advances in the genetic knowledge of such microorganisms may lead to discoveries which will clarify the most active microorganisms that act as bioprotectants in bodies exposed to Cr(VI) and are an affordable option for people and animals intoxicated by the oral route. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  15. Agroindustrial Waste for Lead and Chromium Biosorption

    Directory of Open Access Journals (Sweden)

    Susana P. Boeykens

    2018-06-01

    Full Text Available There is a need to re-evaluate the residues generated in industrial processes for the production of new raw material, reducing the volume of waste. In this regard, the biosorption is a low-cost alternative method for treating effluents compared to conventional methods. The main objectives of this research were: the evaluation of the biosorbent capacity of six waste materials for the extraction of chromium(VI and lead(II ions from aqueous solutions and, the determination of the adsorption and kinetic parameters for the more efficient system. The materials evaluated were: peanut shell (Arachis hypagaea, sugarcane bagasse (Saccharum officinarum, avocado peel (Persea americana, pecan nutshell (Carya illinoinensis, wheat bran (Triticum aestivum and banana peel (Mussa paradisiaca. The highest percentage of lead removal was obtained with wheat bran (89%. For chromium, the percentage was generally much lower compared with lead for all tested biosorbents, the banana peel being the most efficient with a 10% removal. The models that better describe the adsorption processes were: Langmuir and Freundlich. The pseudo-second order kinetic model allowed obtaining the parameters for both systems. The equilibrium time, in both systems, was reached after 60 minutes. The study of Fourier Transformed Infrared spectra and the results of desorption experiments allowed to hypothesize on the mechanisms involved in the adsorption of these metals.

  16. Chromium content in human skin after in vitro application of ordinary cement and ferrous-sulphate-reduced cement

    DEFF Research Database (Denmark)

    Fullerton, A; Gammelgaard, Bente; Avnstorp, C

    1993-01-01

    The amount of chromium found in human skin after in vitro application of cement suspensions on full-thickness human skin in diffusion cells was investigated. Cement suspensions made from ordinary Portland cement or Portland cement with the chromate reduced with added ferrous sulphate were used....... The cement suspensions were either applied on the skin surface under occlusion for 48 h or applied repeatedly every 24 h for 96 h. No statistically significant difference in chromium content of skin layers between skin exposed to ordinary Portland cement, skin exposed to cement with added ferrous sulphate...... and unexposed skin was observed, despite a more permeable skin barrier at the alkaline pH of the cement suspensions, i.e., pH 12.5. Increased chromium levels in epidermis and dermis were seen when ordinary Portland cement was applied as a suspension with added sodium sulphate (20%) on the skin surface for 96 h...

  17. Evaluation of NaX and NaY packed beds for chromium uptake from multicomponent solution

    Directory of Open Access Journals (Sweden)

    Maria Angélica Simões Dornellas de Barros

    2014-04-01

    Full Text Available In this paper the removal of chromium from Cr/Ca/Mg/K and Cr/Ca/Mg/K/Na solutions was investigated in NaX and NaY packed beds. The breakthrough curves presented some overshooting phenomena where chromium ions displaced the previous exchanged cations. Length of unused bed, overall mass transfer coefficient, operational ratio and dimensionless variance were obtained. According to such mass transfer parameters it was concluded that the chromium uptake is influenced by the competition and interaction of the entering ions. Such influences were verified through some differences in the dynamic selectivity obtained for each system. NaY seemed to have a higher affinity towards Cr3+ and its sites were more efficiently used in the ion exchange process.

  18. Effects of surface chromium depletion on localized corrosion of alloy 825 as a high-level nuclear waste container material

    International Nuclear Information System (INIS)

    Dunn, D.S.; Sridhar, N.; Cragnolino, G.A.

    1995-01-01

    Effects of the chromium-depleted, mill-finished surface on the localized corrosion resistance of alloy 825 (UNS N08825) were investigated. Tests were conducted in solutions based on the ground water at Yucca mountain, Nevada, but with a higher concentration of chloride. Results indicated that breakdown (E p ) and repassivation (E rp ) potentials for mill-finished surfaces were more active than those for polished surfaces. Potentiodynamic polarization tests indicated pits could be initiated on the chromium-depleted surface at potentials of 220 mV SCE in a solution containing 1,000 ppm Cl - at 95 C. Potentiostatic tests identified a similar pit initiation potential for the mill-finished surface. However, under longterm potentiostatic tests, a higher potential of 300 mV SCE was needed to sustain stable pit growth beyond the chromium-depleted layer. An increase in surface roughness also was observed to decrease localized corrosion resistance of the material

  19. Relation of Nickel Allergy with in-Stent Restenosis in Patients Treated with Cobalt Chromium Stents

    OpenAIRE

    Aliağaoğlu, Cihangir; Turan, Hakan; Erden, İsmail; Albayrak, Hülya; Özhan, Hakan; Başar, Cengiz; Gürlevik, Zehra; Alçelik, Ayşegül

    2012-01-01

    Background In-stent restenosis (ISR) is the major limitation of percutaneous coronary stenting procedure. The elements like nickel, chromate and molybdenum are known to cause contact allergy. Hypersensitivity reaction, against these metal ions, may be one of the reasons of ISR. Cobalt chromium coronary stents, which are increasingly being used in percutaneous coronary interventions, have more nickel amount than the stainless steel stents. Objective We aimed to investigate the association betw...

  20. Study of interaction products of chromium, molybdenum and tungsten carbonyls with ethanolamines

    Energy Technology Data Exchange (ETDEWEB)

    Mozgin, S.V.; Felin, M.G.; Subbotina, N.A.; Spitsyn, V.I. (Moskovskij Gosudarstvennyj Univ. (USSR))

    1982-11-01

    The interaction of the 6th group metal carbonyls with mono-, di-, and triethanolamines was investigated. It was established that chromium, molybdenum and tungsten carbonyls could react with ethanolamines. Complex compounds of the mentioned metals that had been separated after carrying out those reactions were characterized by chemical analysis data. Properties of the produced complexes were studied by methods of UV, visible and IR spectroscopy, thermomagnetic and thermal analyses and their structure is proposed.

  1. Electrodeposited nanocrystalline Ni-Co and Co-Ni-P coatings for hard chromium replacement

    OpenAIRE

    Ma, Chao

    2013-01-01

    This thesis describes the preparation and characterisation of environmentally friendly and low-cost nanocrystalline Ni-Co coatings and Co-Ni-P coatings to replace hard chromium coatings for anti-wear and anti-corrosion applications. nanocrystalline Ni–Co coatings with different cobalt contents were electrodeposited.The investigation on the role of tribofilms and wear debris in the tribological behavior sliding against AISI-52100 stainless steel under unlubricated conditions shows that the tri...

  2. Investigations of radionuclide production in a spallation target carried out in the frame of MUSE and SAD projects

    Energy Technology Data Exchange (ETDEWEB)

    Pohorecki, W.; Janczyszyn, J; Taczanowski, S. [AGH-University of Science and Technology, Faculty of Nuclear Physics, Al Mickiewicza 30, PL-30059 Krakow (Poland); Mirokhin, I.V.; Molokanov, A.G. [Dzhelepov Laboratory of Nuclear Problems, Joint Institute of Nuclear Research, JINR, 6 Joliot Curie Street, Dubna, Moscow Region 141980 (Russian Federation); Horwacik, T. [Institute of Nuclear Physics, ul. Radzikowskiego 152 31-342 Cracow (Poland); Polanki, A. [Laboratory of Information Technologies, Joint Institute for Nuclear Research, 6 Joliot Curie Street, Dubna, Moscow Region 141980 (Russian Federation)

    2004-07-01

    Designing of an accelerator driven system needs a thorough evaluation of build-up of long-lived radioactivity and changes in elemental composition in construction materials. This data can be only calculated with the use of experimentally verified computer codes and data libraries. The present experiment is thought as a part of such validation. Two types of detectors were irradiated inside and/or on the surface of a cylindrical Pb targets irradiated with 660 MeV protons: activation detectors made of typical target materials - Pb, Bi, and track detectors with heavy metal radiators - Bi, Pb, Au, W, Ta. Activities of several radionuclides in Pb and Bi samples were determined and compared with values obtained from LAHET, MCNPX and FLUKA-2002 calculations. In the track detectors density of tracks and their size distributions were measured. (authors)

  3. EXTRACTION AND SPECIATION OF CHROMIUM(VI AND CHROMIUM(III AS ION-ASSOCIATION COMPLEXES OF TETRAMETHYLAMMONIUM-CHROMATE

    Directory of Open Access Journals (Sweden)

    Valencia Widiyaningrum Wandoyo

    2010-06-01

    Full Text Available A specific, selective and simple method for speciation of chromium(VI and chromium(III has been developed. This method is based on the quantitative extraction of chromium(VI and chromium(III as an ion association of tetramethylammonium-chromate in methyl isobutyl ketone (MIBK, followed by back extraction and preconcentration with an acidic diphenylcarbazide (DPC solution. Back extraction was applied to achieve further preconcentration by a final factor of 20. The chromium(VI-DPC complex was determined by a UV-Visible spectrophotometer. The optimum conditions of this method are as follows, optimum wavelength at 545 nm, MIBK as organic solvent, 7.5 mL of nitric acid (65% for each 100 mL sample, mole ratio of TMAC to Cr(VI of 2x104:1, 5 min shaking time, mole ratio of DPC to chromium(VI of 8:1, and immediate UV-Vis measurement after obtaining of back-extract. The calibration curve was linear in the concentration range 0.00-0.40 µg.mL-1 of chromium(VI with a regression equation of Abs=0.0038+1.7427x, in which x was the chromium species concentration ( µg.mL-1. The correlation coefficient (r for the curve was 0.9991 and the detection limit was found to be 0.946 µg.mL-1. The result of analysis and speciation of chromium in water samples from a river near a leather processing plant in Yogyakarta area showed that the total content of chromium was in the range of 0.04 - 0.05 µg.mL-1 consisting of 0.03 - 0.04 µg.mL-1 of chromium(VI and 0.002 - 0.01 µg.mL-1 of chromium(III. This result indicates that the concentration of chromium in the river is still below the safety limit.   Keywords: extraction, speciation, chromium, preconcentration, ion-association, tetramethylammonium

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

    Directory of Open Access Journals (Sweden)

    Abdulsalam A. Shyaa

    2015-01-01

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

  5. Chromium(VI Removal from Aqueous Solution by Magnetite Coated by a Polymeric Ionic Liquid-Based Adsorbent

    Directory of Open Access Journals (Sweden)

    Thania Alexandra Ferreira

    2017-05-01

    Full Text Available An evaluation of the chromium(VI adsorption capacity of four magnetite sorbents coated with a polymer phase containing polymethacrylic acid or polyallyl-3-methylimidazolium is presented. Factors that influence the chromium(VI removal such as solution pH and contact time were investigated in batch experiments and in stirred tank reactor mode. Affinity and rate constants increased with the molar ratio of the imidazolium. The highest adsorption was obtained at pH 2.0 due to the contribution of electrostatic interactions.

  6. Removal of toxic chromium from aqueous solution, wastewater and saline water by marine red alga Pterocladia capillacea and its activated carbon

    Directory of Open Access Journals (Sweden)

    Ahmed El Nemr

    2015-01-01

    Full Text Available Pterocladia capillacea, a red marine macroalgae, was tested for its ability to remove toxic hexavalent chromium from aqueous solution. A new activated carbon obtained from P. capillacea via acid dehydration was also investigated as an adsorbent for toxic chromium. The experiments were conducted to study the effect of important parameters such as pH, chromium concentration and adsorbent weight. Batch equilibrium tests at different pH conditions showed that at pH 1.0, a maximum chromium uptake was observed for both inactivated dried red alga P. capillacea and its activated carbon. The maximum sorption capacities for dried red alga and its activated carbon were about 12 and 66 mgg−1, respectively, as calculated by Langmuir model. The ability of inactivated red alga P. capillacea and developed activated carbon to remove chromium from synthetic sea water, natural sea water and wastewater was investigated as well. Different isotherm models were used to analyze the experimental data and the models parameters were evaluated. This study showed that the activated carbon developed from red alga P. capillacea is a promising activated carbon for removal of toxic chromium.

  7. Determination of chromium(III) and total chromium using dual channels on glass chip with chemiluminescence detection.

    Science.gov (United States)

    Som-Aum, Waraporn; Threeprom, Jirasak; Li, Haifang; Lin, Jin-Ming

    2007-03-30

    A simple, rapid and sensitive method for the determination of chromium(III) and total chromium using the simple dual T channels on glass chip with negative pressure pumping system and chemiluminescence (CL) detection is presented. The CL reaction was based on luminol oxidation by hydrogen peroxide in basic aqueous solution catalyzed by chromium(III). Total chromium in form of chromium(III) was achieved after chromium(VI) was completely reduced by acidic sodium hydrogen sulfite. Total chromium could then be determined with the same strategy as the chromium(III). The CL reagent was composed of 1.0x10(-4)mol/L luminol, 1.0x10(-2)mol/L hydrogen peroxide and 0.10mol/L sodium bromide in 0.050mol/L carbonate buffer (pH 11.00). The 1.0x10(-2)mol/L ethylenediaminetetraacetic acid was added into the sample solution in order to improve the selectivity. Chromium(III) could be detected at a notably concentration of 1.6x10(-16)mol/L and a linear calibration curve was obtained from 1.0x10(-15) to 1.0x10(-13)mol/L. The sample and CL reagent consumption were only 15 and 20microL, respectively. The analysis time was less than 1 min per sample with the precision (%R.S.D.) was 4.7%. The proposed method has been applied successfully to the analysis of river water, mineral waters, drinking waters and tap water. Its performance was verified by the analysis of certified total chromium-reference materials and by recovery measurement on spiked synthetic seawater sample.

  8. Coordination chemistry of sterically encumbered pyrrolyl ligands to chromium(II): mono(pyrrolyl)chromium and diazachromocene formation.

    Science.gov (United States)

    Kreye, Markus; Daniliuc, Constantin G; Freytag, Matthias; Jones, Peter G; Walter, Marc D

    2014-06-28

    A series of diazachromocenes with sterically demanding pyrrolyl ligands, 2,5-(Me3C)2C4H2N (1), 2,5-(Me3C)2-3,4-Me2C4N (2) and 2,3,5-(Me3C)3C4HN (3), was prepared and investigated by various spectroscopic techniques, and in some cases by X-ray diffraction and magnetic susceptibility studies. The diazachromocenes exhibit an S = 1 ground state; no indication of a spin-equilibrium was obtained. With the same ligands mono(pyrrolyl)chromium(II) complexes are accessible, [{(κN-2,5-(Me3C)2C4H2N)Cr(thf)}2(μ-Cl)2] (1-CrCl(thf)), [(κN-2,5-(Me3C)2-3,4-Me2-C4H2N)Cr(Cl)(tmeda)] (2-CrCl(tmeda) and [(η(5)-2,3,5-(Me3C)3C4HN)Cr(μ-Cl)2] (3-CrCl), which show either η(5)- or η(1)-(κN) coordination depending on the substitution pattern. (1)H NMR spectroscopy serves as a valuable tool to distinguish between these coordination modes. The Cr(II) atoms in the mono(pyrrolyl) complexes adopt a high spin configuration (S = 2) and in dimeric species antiferromagnetic coupling between the spin carriers was observed. However, none of these mono(pyrrolyl)chromium complexes is an effective or selective ethylene oligomerization catalyst on activation with MAO or AlMe3, supporting the importance of a Cr(I)/Cr(III)-based catalytic cycle.

  9. 77 FR 39141 - Defense Federal Acquisition Regulation Supplement: Applicability of Hexavalent Chromium Policy to...

    Science.gov (United States)

    2012-06-29

    ... 0750-AH39 Defense Federal Acquisition Regulation Supplement: Applicability of Hexavalent Chromium... policies relating to the use of material containing hexavalent chromium. DATES: Effective Date: June 29... environmental risks related to the use of hexavalent chromium. Hexavalent chromium is a chemical that has been...

  10. Electrochemical modification of chromium surfaces using 4-nitro- and4-fluorobenzenediazonium salts

    DEFF Research Database (Denmark)

    Hinge, Mogens; Cecatto, Marcel; Kingshott, Peter

    2009-01-01

    Chromium surfaces can be electrografted with organic surface films using 4-nitro- or 4-fluorobenzenediazonium salts, despite the fact that the surfaces are covered with a protective chromium oxide layer......Chromium surfaces can be electrografted with organic surface films using 4-nitro- or 4-fluorobenzenediazonium salts, despite the fact that the surfaces are covered with a protective chromium oxide layer...

  11. 76 FR 71926 - Defense Federal Acquisition Regulation Supplement: Applicability of Hexavalent Chromium Policy to...

    Science.gov (United States)

    2011-11-21

    ... 0750-AH39 Defense Federal Acquisition Regulation Supplement: Applicability of Hexavalent Chromium... the use of materials containing hexavalent chromium. DATES: Comment Date: Comments on the proposed... human health and environmental risks related to the use of hexavalent chromium. Hexavalent chromium is a...

  12. 40 CFR 424.70 - Applicability; description of the electrolytic chromium subcategory.

    Science.gov (United States)

    2010-07-01

    ... electrolytic chromium subcategory. 424.70 Section 424.70 Protection of Environment ENVIRONMENTAL PROTECTION... Electrolytic Chromium Subcategory § 424.70 Applicability; description of the electrolytic chromium subcategory. The provisions of this subpart are applicable to discharges resulting from the manufacture of chromium...

  13. Investigating the effect of a targets time-varying doppler generating axis of rotation on isar image distortion

    CSIR Research Space (South Africa)

    Abdul Gaffar, MY

    2007-10-01

    Full Text Available of the target and transformations between two co-ordinate systems can be expressed using quaternion algebra. 2.1 The quaternion as a rotational operator The concept of quaternions was introduced by Hamilton as an extension of complex numbers [9, 10... quaternion multiplication and a , b are quaternion vectors of the 3-D vectors a and b . Note that the rotated point b in 3D is given by the vector component of the quaternion b . 2.2 Transformation from the local to the global co- ordinate frame...

  14. Towards real-time spectroscopic process control for the dehydrogenation of propane over supported chromium oxide catalysts

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Nijhuis, T.A.; Tinnemans, S.J.; Visser, T.

    2004-01-01

    UV–Vis and Raman spectroscopy are applied under realistic reaction conditions to investigate the changes occurring to an industrial-like supported chromium oxide catalyst during the dehydrogenation of propane. Linking the catalytic activity to the simultaneously collected spectroscopic data has

  15. Chromium regulation of multiple gene expression in rats with high-fructose diet-induced metabolic syndrome

    Science.gov (United States)

    Chromium (Cr) supplementation alleviates the metabolic syndrome, glucose intolerance, depression, excess body fat, and type 2 diabetes. However, not all studies have reported beneficial effects of Cr. Molecular evidence is lacking on the effects of Cr. The objective of this study was to investigate ...

  16. Bioavailability of a potato chromium complex to the laboratory rat

    International Nuclear Information System (INIS)

    Gilbert, H.K.

    1985-01-01

    Research objectives were to study the effect of food source, preparation method and chemical form on bioavailability of chromium. Chromium concentration in potatoes was determined and tubers labeled either intrinsically or extrinsically with radioactive chromate. A labeled chromium complexes was isolated from preparations of raw, baked or fried potatoes and chromatographed on gel permeation media. Availability of the potato chromium complex to the rat was examined in three feeding studies. Animals were dosed with radioactive extrinsically or intrinsically labeled potato extract or with chromate. A labeled chromium complex was isolated from gastrointestinal contents of rats and chromatographed. Potato pulp and peel contained 1.63 and 2.70 μg Cr/g tissue respectively. True and apparent absorption from extrinsically labeled feedings were 33.4 +/- 4.7 and 29.8 +/- 11.2% respectively, and no differences existed between absorption from raw and cooked potatoes. Absorption from the extrinsic labeled potatoes differed significantly from absorption of inorganic chromatium. Apparent absorption of raw (11.1 +/- 7.9%) and cooked (-0.7 +/- 2.8%) intrinsically labeled feedings differed significantly. Absorption of inorganic chromium was 17.8% (true) and 11.5% (apparent). Examination of the chromium complex isolated from gastrointestinal tract contents showed enlargement of the complex in the stomach after consumption

  17. Substoichiometric determination of chromium by neutron activation analysis

    International Nuclear Information System (INIS)

    Kudo, K.; Shigematsu, T.; Kobayashi, K.

    1977-01-01

    A method of radioactivation analysis has been developed for the determination of chromium. It is based on the substoichiometric extraction of chromium diethyldithiocarbamate into methyl-isobutyl-ketone from acetate buffer solution in the presence of EDTA and potassium cyanide. A solution of NaDDC was prepared by dissolving an appropriate amount of GR grade salt in bidistelled water. The concentration of NaDDC was determined by substoichiometric isotope dilution method using 64 Cu or sup(114m)In tracer of known specific activity. The extraction of chromium is not influenced by the presence of EDTA or potassium cyanide while the extraction of chromium is inhibited in tartrate or citrate solution. All metal ions examined are extracted by NaDDC together with chromium and become to interfere for the substoichiometric extraction of chromium. This can be avoided, however, by the addition of EDTA except for copper and silver. The method has been applied for the determination of chromium in high-purity calcium carbonate and NBS glasses as standard reference materials. (T.G.)

  18. Electro-deposition behaviors of trivalent chromium during pulse plating

    Science.gov (United States)

    Choi, Yong

    2010-10-01

    Thick trivalent chromium layers were prepared in a modified chromium sulfate bath by pulse plating to replace hexavalent hard chromium coating in industrial fields; layer microstructure development was systematically studied by using electron microscopy and small angle neutron scattering (SANS) to give a model for nucleation and growth behaviors during the pulse plating. Finer columnar grain was formed by pulse plating due to its high nucleation rate at the same current density. Average deposition rate of the trivalent chromium layers is in the range of 32.4 μm/h to 49.7 μm/h. The deposition rate increases as the diameter of cylindrical shape of chromium cluster in a columnar grain is reduced. The highest deposition rate in this study was observed under the conditions of direct current density of 0.4 Acm-2, combined with a rectangular shape pulse current density of 1.5 Acm-2 with a 10/2 on-off time ratio. Most of the inner-cracks of the trivalent chromium layers have dimensions in the range of about 39 nm. Ultrasonic agitation during pulse plating resulted in an increase of neutral salt fog spray life, which is related to smaller crack size and broader size distribution in the trivalent chromium.

  19. Workshop on effects of chromium coating on Nb3Sn superconductor strand: Proceedings

    International Nuclear Information System (INIS)

    1994-01-01

    This report discusses the following topics: Chromium coating on superconductor strand -- an overview; technology of chromium plating; comparison of wires plated by different platers; search for chromium in copper; strand manufactures' presentations; chromium plating at the Lawrence Livermore National Laboratory; a first look at a chromium plating process development project tailored for T.P.X. and I.T.E.R. strand; and influence of chromium diffusion and related phenomena on the reference ratios of bare and chromium plated Nb 3 Sn strand

  20. A Monte Carlo investigation of low-Z target image quality generated in a linear accelerator using Varian's VirtuaLinac

    International Nuclear Information System (INIS)

    Parsons, David; Robar, James L.; Sawkey, Daren

    2014-01-01

    Purpose: The focus of this work was the demonstration and validation of VirtuaLinac with clinical photon beams and to investigate the implementation of low-Z targets in a TrueBeam linear accelerator (Linac) using Monte Carlo modeling. Methods: VirtuaLinac, a cloud based web application utilizing Geant4 Monte Carlo code, was used to model the Linac treatment head components. Particles were propagated through the lower portion of the treatment head using BEAMnrc. Dose distributions and spectral distributions were calculated using DOSXYZnrc and BEAMdp, respectively. For validation, 6 MV flattened and flattening filter free (FFF) photon beams were generated and compared to measurement for square fields, 10 and 40 cm wide and at d max for diagonal profiles. Two low-Z targets were investigated: a 2.35 MeV carbon target and the proposed 2.50 MeV commercial imaging target for the TrueBeam platform. A 2.35 MeV carbon target was also simulated in a 2100EX Clinac using BEAMnrc. Contrast simulations were made by scoring the dose in the phosphor layer of an IDU20 aSi detector after propagating through a 4 or 20 cm thick phantom composed of water and ICRP bone. Results: Measured and modeled depth dose curves for 6 MV flattened and FFF beams agree within 1% for 98.3% of points at depths greater than 0.85 cm. Ninety three percent or greater of points analyzed for the diagonal profiles had a gamma value less than one for the criteria of 1.5 mm and 1.5%. The two low-Z target photon spectra produced in TrueBeam are harder than that from the carbon target in the Clinac. Percent dose at depth 10 cm is greater by 3.6% and 8.9%; the fraction of photons in the diagnostic energy range (25–150 keV) is lower by 10% and 28%; and contrasts are lower by factors of 1.1 and 1.4 (4 cm thick phantom) and 1.03 and 1.4 (20 cm thick phantom), for the TrueBeam 2.35 MV/carbon and commercial imaging beams, respectively. Conclusions: VirtuaLinac is a promising new tool for Monte Carlo modeling of novel

  1. Spectroscopic analysis of chromium bioremediation products

    Science.gov (United States)

    Varadharajan, C.; Nico, P. S.; Yang, L.; Marcus, M. A.; Steefel, C.; Larsen, J. T.; Beller, H. R.; Brodie, E. L.

    2010-12-01

    Remediation of chromium contamination frequently involves reducing the toxic and soluble hexavalent form, Cr(VI), to the relatively harmless and mostly immobile trivalent state, Cr(III). The objective of this study is to identify the biogeochemical reactions that control in situ chromium reduction in the presence of different dominant electron acceptors, i.e., NO3-, Fe(III), and SO42-. It was hypothesized that indirect, abiotic reduction of Cr(VI) by reduced metabolic products [Fe(II) and sulfides] would dominate over direct enzymatic reduction by denitrifying, iron-reducing, or sulfate-reducing bacteria. It is further hypothesized that the enzymatic reduction of Cr(VI) would produce relatively pure chromium hydroxide precipitates, whereas indirect reduction would result in mixed Cr-Fe hydroxide solid phases. Flow-through columns containing homogenized sediments from the 100H site at Hanford, WA were subjected to nitrate-, sulfate- or iron-reducing conditions in the presence of 5 µM Cr(VI) and 5 mM lactate. Cr(VI) was depleted in the effluent solutions from the nitrate- and sulfate-reducing columns; however only a small amount of Cr(VI) was removed under iron-reducing conditions. Preliminary analysis of micro X-ray absorption spectra indicate that the untreated and iron-reducing column sediments contained pre-existing Cr in the form of primary minerals, e.g. chromite and/or Cr-bearing micas. However, there was an increase in the relative abundance of mixed-phase Cr-Fe hydroxides, i.e., Cr1-xFex(OH)3 in the nitrate- and sulfate-treated columns. A possible explanation for the observations is that the production of Fe(II) was enhanced under the nitrate- and sulfate- reducing conditions, and was most likely sulfide-driven in the latter case. The Fe(II) was subsequently available for reduction of Cr(VI) resulting in the mixed-phase precipitates. The results from the spectroscopic analysis support the hypothesis that Fe(II)-mediated Cr reduction prevails over direct

  2. Plasma Spraying and Characterization of Chromium Carbide-Nickel Chromium Coatings

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Prantnerová, M.

    2016-01-01

    Roč. 9, č. 4 (2016), s. 281-290, č. článku PCCC-2016-09-16-339. ISSN 2008-2134 Institutional support: RVO:61389021 Keywords : Plasma spraying * Chromium carbide * Slurry abrasion * Dry rubber wheel test * Friction * Microhardness Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass http://www.pccc.icrc.ac.ir/?xid=0113010121000001804&id=976

  3. Chromium recovery from sludges produced from chromate-inhibited cooling water

    International Nuclear Information System (INIS)

    Deacon, L.E.; Holland, M.E.; Kaplan, R.I.

    1975-01-01

    Laboratory investigations of methods to reclaim chromium from sludge are summarized. Among the methods tried were wet oxidation techniques using peroxide, persulfate, and permanganate salts as oxidants and gaseous oxidation techniques using ozone, chlorine, and fluorine. However, the most successful and technically feasible approach discovered was calcination of the sludge with added soda ash at 850 to 900 0 C for about 30 minutes in an open-air calciner. Recovery yields of up to 75 percent were recorded. Calcination converts the chromium to sodium chromate, which is water-leachable and, hence, can be returned to the cooling water system. Residue after leaching may contain sufficient lime to warrant its reuse as a precipitation agent in the process

  4. Tensile strength of laser welded cobalt-chromium alloy with and without an argon atmosphere.

    Science.gov (United States)

    Tartari, Anna; Clark, Robert K F; Juszczyk, Andrzej S; Radford, David R

    2010-06-01

    The tensile strength and depth of weld of two cobalt chromium alloys before and after laser welding with and without an argon gas atmosphere were investigated. Using two cobalt chromium alloys, rod shaped specimens (5 cm x 1.5 mm) were cast. Specimens were sand blasted, sectioned and welded with a pulsed Nd: YAG laser welding machine and tested in tension using an Instron universal testing machine. A statistically significant difference in tensile strength was observed between the two alloys. The tensile strength of specimens following laser welding was significantly less than the unwelded controls. Scanning electron microscopy showed that the micro-structure of the cast alloy was altered in the region of the weld. No statistically significant difference was found between specimens welded with or without an argon atmosphere.

  5. Study on the DNA-protein crosslinks induced by chromium (VI) in SPC-A1

    Science.gov (United States)

    Liu, Yanqun; Ding, Jianjun; Lu, Xiongbing; You, Hao

    2018-01-01

    Objective: This study was designed to investigate the effect of chromium (VI) on DNA-protein crosslinks (DPC) of SPC-A1 cells. Methods: We exposed SPC-A1 cells were cultured in 1640 medium and treated with the SPC-A1 cells in vitro to different concentrations of Hexavalent chromium Cr(VI) for 2h, the KC1-SDS precipitation assay were used to measure the DNA-protein cross-linking effect. Results: All the different concentrations of Cr(VI) could cause the increase of DPC coefficient in SPC-A1 cells. But this effect was not significant (P>0.05) at low concentrations; while in high concentration Cr(VI) induced SPC-A1 cells could produce DNA-protein cross-linking effect significantly (PDNA-protein crosslink.

  6. Sublethal Effects of Chromium on Enzymatic Activities of the African Catfish: Clarias Gariepinus (Burchell, 1822

    Directory of Open Access Journals (Sweden)

    Ovie KORI-SIAKPERE

    2012-02-01

    Full Text Available The effect of sublethal concentration (0.00, 2.00, 4.00 and 8.00 mg/l of chromium was determined on the activities of some enzymes (creatine-kinase, lactate dehydrogenase, cholinesterase, gamma glutamyltransferase in the plasma, liver and kidney of the exposed juvenile African Catfish Clarias gariepinus (length 23.000.86 cm and weight 96.975.31 g respectively after the 7 days exposure period. The activity of lactate dehydrogenase was significantly (p0.05 in plasma and liver and a significant decrease (p0.05 in plasma, liver and kidney expect liver creatine-kinase that was significantly decreased. Generally, the activities of the determined enzymes were most significant in the liver than in plasma and kidney. Therefore, sublethal concentrations of chromium have some deleterious effect on the basic activities of enzymes of the plasma, liver and kidney of Clarias gariepinus as revealed in this investigation.

  7. A REVIEW OF BIOSORPTION OF CHROMIUM IONS BY MICROORGANISMS

    Directory of Open Access Journals (Sweden)

    Inga Zinicovscaia

    2012-12-01

    Full Text Available Due to its widespread industrial use, chromium has become a serious pollutant in diverse environmental settings. The main source of chromium pollution including the Republic o Moldova is industry. It is a great need to develop new eco-friendly methods of chromium removal. Biosorption of heavy metals is a most promising technology involved in the removal of toxic metals from industrial waste streams and natural waters. This article is an extended abstract of a communication presented at the Conference Ecological Chemistry 2012

  8. Surfactant Enhanced Chromium Removal Using a Silica Gel Column

    Directory of Open Access Journals (Sweden)

    N. Rajesh

    2001-06-01

    Full Text Available A simple and rapid method is proposed for the removal of chromium based on its adsorption as an ion pair with Cetyl Trimethyl Ammonium Bromide (CTABr on a silica gel colurnn. The surfactant (CTABr is bonded to chromate by electrostatic force of attraction and the resulting ion-association complex is held on a silica gel column. The resulting solution from the column is analyzed for chromium by the standard diphenyl carbazide spectrophotometric procedure. The method has been applied successfully to study the recovery of chromium in various synthetic mixtures.

  9. Chromium removal from tannery wastewater by using of flying ash

    International Nuclear Information System (INIS)

    Gil P, E.; Saldarriaga M, C.

    1998-01-01

    A simple and economic method to chromium removal from tannery wastewater by means of flying ash is presented. The chromium removal operation is a discontinuous process that involve the mass of flying ash, time of contact and temperature or ph as variables, their which are optimized through Box-Wilson type experimental design. The results were successful: From an initial fluid whit chromium concentration of 1850m ppm, final concentrations of 0.008 ppm and 0.5 ppm of Cr+3 and Cr+6 respectively were achieved. These post-treatment concentrations are into the approved range definite by Government's Laws to this waste type

  10. Germination and seedling growth of Indian mustard exposed to cadmium and chromium

    Directory of Open Access Journals (Sweden)

    Giuseppe Zerbi

    2006-03-01

    Full Text Available To make phytoremediation a technically viable option for large-scale applications we need plants that are able to guarantee high biomass yield as well as high accumulation of heavy metals in their aerial parts. The aim of this investigation was to study the performance of aquacultured plants of Indian mustard in the presence of different concentrations of cadmium and chromium since seed germination. The effects on germination and growth of seedlings of Indian mustard (Brassica juncea L. Czern cv. WNFP, Varuna and Barton, were investigated in/under hydroponic conditions during a 4-week experiment. Cadmium and chromium were provided since germination as cadmium nitrate Cd(NO32 and chromium bichromate K2Cr2O7 (0.5, 1 and 1.5 M. Plant biomass growth measured at the end of the experiments varied with the different metal concentrations in the nutrient solution and the accumulation of the elements in the plant fractions differed significantly among/between cultivars. Ability in the uptake of metals and their mobilization and storage in the aerial plant biomass, expressed by the bioconcentration factor (BCF and translocation factor (TF, respectively, are the most important traits of plants with phytoextraction potential. Brassica juncea was confirmed as being a highly tolerant species, but poor metal translocation values were registered, therefore the high amount of Cd and Cr concentrated in the root systems did not migrate to the aerial, harvestable, part of the plant.

  11. Selenium, Vanadium, and Chromium as Micronutrients to Improve Metabolic Syndrome.

    Science.gov (United States)

    Panchal, Sunil K; Wanyonyi, Stephen; Brown, Lindsay

    2017-03-01

    Trace metals play an important role in the proper functioning of carbohydrate and lipid metabolism. Some of the trace metals are thus essential for maintaining homeostasis, while deficiency of these trace metals can cause disorders with metabolic and physiological imbalances. This article concentrates on three trace metals (selenium, vanadium, and chromium) that may play crucial roles in controlling blood glucose concentrations possibly through their insulin-mimetic effects. For these trace metals, the level of evidence available for their health effects as supplements is weak. Thus, their potential is not fully exploited for the target of metabolic syndrome, a constellation that increases the risk for cardiovascular disease and type 2 diabetes. Given that the prevalence of metabolic syndrome is increasing throughout the world, a simpler option of interventions with food supplemented with well-studied trace metals could serve as an answer to this problem. The oxidation state and coordination chemistry play crucial roles in defining the responses to these trace metals, so further research is warranted to understand fully their metabolic and cardiovascular effects in human metabolic syndrome.

  12. Ultrasound effects on brain-targeting mannosylated liposomes: in vitro and blood–brain barrier transport investigations

    Directory of Open Access Journals (Sweden)

    Zidan AS

    2015-07-01

    Full Text Available Ahmed S Zidan,1,2 Hibah Aldawsari1 1Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia; 2Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Zagazig University, Zagazig, Egypt Abstract: Delivering drugs to intracerebral regions can be accomplished by improving the capacity of transport through blood–brain barrier. Using sertraline as model drug for brain targeting, the current study aimed at modifying its liposomal vesicles with mannopyranoside. Box-Behnken design was employed to statistically optimize the ultrasound parameters, namely ultrasound amplitude, time, and temperature, for maximum mannosylation capacity, sertraline entrapment, and surface charge while minimizing vesicular size. Moreover, in vitro blood–brain barrier transport model was established to assess the transendothelial capacity of the optimized mannosylated vesicles. Results showed a dependence of vesicular size, mannosylation capacity, and sertraline entrapment on cavitation and bubble implosion events that were related to ultrasound power amplitude, temperature. However, short ultrasound duration was required to achieve >90% mannosylation with nanosized vesicles (<200 nm of narrow size distribution. Optimized ultrasound parameters of 65°C, 27%, and 59 seconds for ultrasound temperature, amplitude, and time were elucidated to produce 81.1%, 46.6 nm, and 77.6% sertraline entrapment, vesicular size, and mannosylation capacity, respectively. Moreover, the transendothelial ability was significantly increased by 2.5-fold by mannosylation through binding with glucose transporters. Hence, mannosylated liposomes processed by ultrasound could be a promising approach for manufacturing and scale-up of brain-targeting liposomes. Keywords: CNS delivery, sizing, lipid based formulations, quality by design, sertraline hydrochloride

  13. SEM and Raman spectroscopy analyses of laser-induced periodic surface structures grown by ethanol-assisted femtosecond laser ablation of chromium

    Science.gov (United States)

    Bashir, Shazia; Shahid Rafique, M.; Nathala, Chandra S. R.; Ajami, Ali; Husinsky, Wolfgang

    2015-05-01

    The effect of fluence and pulse duration on the growth of nanostructures on chromium (Cr) surfaces has been investigated upon irradiation of femtosecond (fs) laser pulses in a liquid confined environment of ethanol. In order to explore the effect of fluence, targets were exposed to 1000 pulses at various peak fluences ranging from 4.7 to 11.8 J cm-2 for pulse duration of ∼25 fs. In order to explore the effect of pulse duration, targets were exposed to fs laser pulses of various pulse durations ranging from 25 to 100 fs, for a constant fluence of 11.8 J cm-2. Surface morphology and structural transformations have been analyzed by scanning electron microscopy and Raman spectroscopy, respectively. After laser irradiation, disordered sputtered surface with intense melting and cracking is obtained at the central ablated areas, which are augmented with increasing laser fluence due to enhanced thermal effects. At the peripheral ablated areas, where local fluence is approximately in the range of 1.4-4 mJ cm-2, very well-defined laser-induced periodic surface structures (LIPSS) with periodicity ranging from 270 to 370 nm along with dot-like structures are formed. As far as the pulse duration is concerned, a significant effect on the surface modification of Cr has been revealed. In the central ablated areas, for the shortest pulse duration (25 fs), only melting has been observed. However, LIPSS with dot-like structures and droplets have been grown for longer pulse durations. The periodicity of LIPSS increases and density of dot-like structures decreases with increasing pulse duration. The chemical and structural modifications of irradiated Cr have been revealed by Raman spectroscopy. It confirms the formation of new bands of chromium oxides and enol complexes or Cr-carbonyl compounds. The peak intensities of identified bands are dependent upon laser fluence and pulse duration.

  14. Outcomes of patients treated with durable polymer platinum-chromium everolimus-eluting stents: a meta-analysis of randomised trials.

    Science.gov (United States)

    Cassese, Salvatore; Ndrepepa, Gjin; Byrne, Robert A; Kufner, Sebastian; Xhepa, Erion; de Waha, Antoinette; Rheude, Tobias; Colleran, Roisin; Giacoppo, Daniele; Harada, Yukinori; Laugwitz, Karl-Ludwig; Schunkert, Heribert; Fusaro, Massimiliano; Kastrati, Adnan

    2017-10-20

    The durable polymer platinum-chromium everolimus-eluting stent (PtCr-EES) is a new-generation drug-eluting stent (DES) with a platinum-enriched metallic platform developed to improve the percutaneous treatment of patients with coronary artery disease. We sought to investigate the performance of durable polymer PtCr-EES versus other new-generation DES. We undertook a meta-analysis of trials in which patients receiving percutaneous coronary intervention (PCI) were randomly assigned to durable polymer PtCr-EES versus other new-generation DES (other DES). Primary efficacy and safety outcomes were target lesion revascularisation (TLR) and definite/probable stent thrombosis (ST), respectively. Secondary outcomes were myocardial infarction (MI), target vessel revascularisation (TVR), death, cardiac death and longitudinal stent deformation (LSD). A total of 11,036 patients in seven trials received a PCI with either durable polymer PtCr-EES (n=6,613) or other DES (n=4,423). This latter group comprised patients treated with biolimus- (n=325), cobalt-chromium everolimus- (n=1,940) or zotarolimus-eluting stents (n=2,158). After a median follow-up of 12 months (interquartile range 12-24), durable polymer PtCr-EES displayed a risk of TLR (odds ratio 0.98, 95% confidence interval [CI]: 0.75-1.29; p=0.90) and definite/probable ST (0.89 [0.55-1.45]; p=0.63) comparable to that of other DES. However, the durable polymer PtCr-EES was associated with a higher risk of LSD (12.05 [1.60-90.71], p=0.02) compared to other DES. There was no significant difference with regard to other secondary outcomes nor was there heterogeneity across trials. At one-year follow-up, the durable polymer PtCr-EES displays a performance comparable to that of other new-generation DES platforms.

  15. High frequency of serum chromium deficiency and association of chromium with triglyceride and cholesterol concentrations in patients awaiting bariatric surgery.

    Science.gov (United States)

    Lima, Karla V G; Lima, Raquel P A; Gonçalves, Maria C R; Faintuch, Joel; Morais, Liana C S L; Asciutti, Luiza S R; Costa, Maria J C

    2014-05-01

    To our knowledge, the frequency of serum chromium deficiency in patients awaiting bariatric surgery has not been determined. This study was designed to assess chromium concentration and its association with glycemic levels and lipid profile in patients prior to bariatric surgery. This study recruited 73 candidates for bariatric surgery between March and September 2012. Their sociodemographic, anthropometric, and biochemical data were collected. Of the 73 patients, 55 (75.3%) were women (75.34%). Mean patient age was 37.20 ± 9.92 years, and mean body mass index was 47.48 kg/m2 (range, 43.59 to 52.50 kg/m2). Chromium deficiency was observed in 64 patients (87.7%). Correlation analysis showed significant negative relationships between chromium concentration and BMI and zinc concentration and a significant positive relationship between chromium and glycated hemoglobin. Multiple linear regression analysis showed that serum chromium concentration was significantly associated with total cholesterol (β = 0.171, p = 0.048) and triglyceride (β = -0.181, p = 0.039) concentrations. Serum chromium deficiency is frequent in candidates for bariatric surgery and is associated with total cholesterol and triglyceride concentrations. Early nutritional interventions are needed to reduce nutritional deficiencies and improve the lipid profile of these patients.

  16. Arsenic and Chromium in Canned and Non-Canned Beverages in Nigeria: A Potential Public Health Concern

    Directory of Open Access Journals (Sweden)

    Orish E. Orisakwe

    2007-03-01

    Full Text Available Numerous studies have described environmental exposure of humans to heavy metals in African populations. Little is known about the exposure to heavy metal toxins from processed or unprocessed foods consumed in Africa, and no data exists on the food concentrations of arsenic and chromium, which are potential carcinogens and systemic toxicants. This study determined the concentrations of arsenic and chromium in beverages and fruit drinks commonly sold in Nigeria. Fifty samples of commonly consumed canned and non-canned beverages (imported and locally manufactured purchased in Nigeria were digested in nitric acid and analyzed by atomic absorption spectrophotometry (AAS. 33.3% of the canned beverages had arsenic levels that exceeded the maximum contaminant level (MCL of 0.01 mg/L set by U.S. EPA while 55.2% of non-canned beverages had their arsenic levels exceeding the MCL. The arsenic concentrations ranged from 0.003 to 0.161 mg/L for the canned and 0.002 to 0.261 mg/l for the non-canned beverages. Whereas 68.9% of the non-canned beverages showed chromium levels that exceeded the US EPA’s MCL of 0.10 mg/L, 76.2% of the canned beverages had chromium levels that were greater than the MCL. The concentration range of total chromium in the canned beverages was 0.04 to 0.59 mg/L and 0.01 to 0.55 mg/L for the non-canned beverages. The sources of arsenic and chromium in the commercially available beverages are unclear and merit further investigation. This preliminary study highlights the need to study the toxicological implications of chronic low-level exposure to heavy metals from African markets.

  17. [The effect of epigallocatechin gallate (EGCG) on the surface properties of nickel-chromium dental casting alloys after electrochemical corrosion].

    Science.gov (United States)

    Qiao, Guang-yan; Zhang, Li-xia; Wang, Jue; Shen, Qing-ping; Su, Jian-sheng

    2014-08-01

    To investigate the effect of epigallocatechin gallate (EGCG) on the surface properties of nickel-chromium dental alloys after electrochemical corrosion. The surface morphology and surface structure of nickel-chromium dental alloys were examined by stereomicroscope and scanning electron microscopy before and after electrochemical tests in 0 g/L and 1.0 g/L EGCG artificial saliva. The surface element component and chemical states of nickel-chromium dental alloys were analyzed by X-ray photoelectron spectrograph after electrochemical tests in 0 g/L and 1.0 g/L EGCG artificial saliva. More serious corrosion happened on the surface of nickel-chromium alloy in 1.0 g/L EGCG artificial saliva than in 0 g/L EGCG. The diameters of corrosion pits were smaller, and the dendrite structure of the alloy surface was not affected in 0 g/L EGCG. While the diameters of corrosion pits were larger, the dendritic interval of the alloy surface began to merge, and the dendrite structure was fuzzy in 1.0 g/L EGCG. In addition, the O, Ni, Cr, Be, C and Mo elements were detected on the surface of nickel-chromium alloys after sputtered for 120 s in 0 g/L EGCG and 1.0 g/L EGCG artificial saliva after electrochemical corrosion, and the surface oxides were mainly NiO and Cr(2)O(3). Compared with 0 g/L EGCG artificial saliva, the content of O, NiO and Cr(2)O(3) were lower in 1.0 g/L EGCG. The results of surface morphology and the corrosion products both show that the corrosion resistance of nickel-chromium alloys become worse and the oxide content of corrosion products on the surface reduce in 1.0 g/L EGCG artificial saliva.

  18. Preplastic strain effect on chromium carbides precipitation of type 316 stainless steel during high-temperature ageing

    International Nuclear Information System (INIS)

    Mao, X.; Zhao, W.

    1992-01-01

    Long exposure of Type 316 stainless steel to elevated temperature (400-900 o C) is known to cause high-temperature embrittlement due to chromium carbides and σ-phase precipitating in grain boundaries. Numerous investigations have been published on the mechanical properties and microstructure changes occurring during such exposure. However, no investigations exist on the preplastic deformation effect on chromium carbide precipitation in the grain matrix and grain boundary during high-temperature ageing of Type 316 stainless steel and then its effects on the room-temperature tensile properties. Since the stainless steel sometimes is deformed before use at high temperatures, it is necessary to study the preplastic strain effect of the stainless steel on the microstructure change and mechanical property change during high-temperature exposure. The purpose of the present investigation was to carry out such a study. The conclusions reached are as follows. First, chromium carbides are precipitated in deformation lines (slip lines) and then the amount of chromium carbides precipitation in the grain boundary is relatively reduced in predeformed stainless steel after ageing. Secondly, plastic strain pretreatments of and subsequent ageing treatments of Type 316 stainless steel can improve its tensile ductility. Finally, secondary cracking of aged stainless steel occurs in a normal tensile test. The secondary cracking can be reduced by adding preplastic strain into the material. (Author)

  19. Cobalt-Chromium Metallosis With Normal Electroretinogram.

    Science.gov (United States)

    Grillo, Lola M; Nguyen, Huy V; Tsang, Stephen H; Hood, Donald C; Odel, Jeffrey G

    2016-12-01

    Ocular cobalt toxicity is a rare phenomenon reported with increased frequency due to the rise of cobalt-chromium metal hip implants. We report the case of a 66-year-old previously healthy man who developed decreased vision due to cobalt-chromium toxicity from a metal-on-metal hip arthroplasty. Our objective was to determine whether the origin of his visual loss was due to toxicity of the optic nerve, of the retina, or of both. Ocular examination, 10-2 SITA-Standard Humphrey Visual Field (VF), standard full-field electroretinogram (ERG) as indicated by the International Society for Clinical Electrophysiology of Vision (ISCEV), multifocal electroretinogram (mfERG), multifocal visual evoked potentials (mfVEP), and optical coherence tomography (OCT) were conducted. Ocular examination revealed decreased visual acuity, poor color vision, normal funduscopy, and cecocentral scotomas on VF testing. Because his right eye was amblyopic since childhood, test results from only the left eye are shown. Electrophysiology studies revealed an ISCEV standard full-field ERG with photopic and scotopic responses within normal limits, mfERG with amplitudes and latencies within normal limits, and mfVEP with latencies within normal limits, but with decreased central amplitudes. Peripapillary and macular OCT showed retinal nerve fiber layer and retinal ganglion cell-inner plexiform layer thickness within normal limits. Because decreased color vision and cecocentral scotoma on 10-2 VF are most consistent with toxic optic neuropathy, and decreased central amplitudes on mfVEP are suggestive of neural dysfunction, we hypothesize that our patient presented with an early stage of optic nerve toxicity that was not yet apparent as a structural abnormality on OCT.

  20. Study of the biosorption of chromium (VI) on crosslinked-quaternary chitosan for their application on the bioremediation of waster waters

    International Nuclear Information System (INIS)

    Diaz, Carlos; Jacinto, Cristian; Medina, Rosa; Navarro, Abel; Cuizano, N.; Llanos, Bertha

    2013-01-01

    In this work, the stoichiometric amounts of the amino-quaternaries and cross-linker were studied to produce the most stable cross-linked quaternary Chitosan (QC2). Preliminary assays were carried out to test the improvement in their mechanical and chemical properties (extreme conditions, surface area and thermogravimetry). Then, the adsorption of chromium (VI) on the QC2 was studied at changing experimental conditions like: pH, adsorbent dose, initial chromium concentration and ionic strength. Moreover, the kinetics of the process was also evaluated as well as the optimization, the desorption of chromium (VI) from the adsorbent for metal recovery and adsorbent recycling. Finally, was characterized by using instrumental techniques such as FTIR, SEM. These tools allowed us to investigate the adsorption mechanism. The calculated parameters indicate a high adsorbent/adsorbato affinity for QC2 with a maximum adsorption capacity of 208 mg g -1 for Cr (VI), elucidating its potential use for the removal of chromium from aqueous solutions. Also showed a pseudo-second order adsorption kinetics with a velocity constant of 0.289 g.mg -1 .min -1 . Desorption of chromium was efficiently accomplish with a mixture of 1M of NaCl and NaOH, reaching a recovery up to 99.78% of the initial metal concentration at pH 4.5. Finally, high ionic strength shows an effect on the adsorption of chromium (VI) onto the studied adsorbents. (author)

  1. Dielectric and spectral properties of DMAAS ferroelectric crystals doped with chromium

    Science.gov (United States)

    Kapustianik, V.; Czapla, Z.; Tchukvinskyi, R.; Batiuk, A.; Eliyachevskyy, Yu.; Korchak, Yu.; Rudyk, V.

    2004-01-01

    This paper presents the results of investigations of the dielectric and spectral properties of NH2(CH3)2Al(SO4)2 × 6 H2O crystals doped with chromium. In particular, it is shown that the dopant noticeably changes the temperature of ferroelectric phase transition and corresponding thermal dipole relaxation with a critical slowing-down at Tc1. The Cr3+ ions were used as a convenient probe for investigations of crystalline structure. On the basis of absorption and luminescence spectroscopy and resonance Raman scattering study it has been shown that the metal-hydrate complexes in the investigated crystals possess the considerably distorted octahedral shape. (

  2. Investigations of RF magnetron sputtered CZTS absorber layer thin films prepared using sulfur induced binary targets without sulfurization

    Science.gov (United States)

    Balaji, G.; Balasundaraprabhu, R.; Prasanna, S.; Prabavathy, N.; McIlroy, D. N.; Kannan, M. D.

    2018-01-01

    Thin films of copper zinc tin sulfide (CZTS), a quaternary semiconductor, was deposited onto well-cleaned soda lime glass substrates using binary sulfur based sputtering targets - copper sulfide (CuS), zinc sulfide (ZnS), and tin sulfide (SnS) by RF Magnetron Sputtering at 300 °C. The stacking order of ZnS/CuS/SnS was used to deposit CZTS thin films. The composition of CZTS thin films were confirmed using X- Ray photoelectron spectroscopy (XPS) and the atomic ratio of the individual elements were quantitatively estimated. X-ray diffraction (XRD) studies were used to understand the CZTS phase formation and the presence of CZTS kesterite phase along direction was detected with the secondary phase of SnS and ZnS. XRD results were validated with Raman results were the presence of CZTS and SnS was corroborated. The optical properties of CZTS thin films were studied using UV-Vis-NIR spectrophotometer where the optical band gap was 1.46 eV and as well as other optical parameters such as interference and optical band gap were ascertained and the results are discussed.

  3. Experimental investigation of the formation of negative hydrogen ions in collisions between positive ions and atomic or molecular targets

    International Nuclear Information System (INIS)

    Lattouf, Elie

    2013-01-01

    The formation of the negative hydrogen ion (H - ) in collisions between a positive ion and a neutral atomic or molecular target is studied experimentally at impact energies of a few keV. The doubly-differential cross sections for H - formation are measured as a function of the kinetic energy and emission angle for the collision systems OH + + Ar and O + + H 2 O at 412 eV/a.m.u. These H - ions can be emitted at high energies (keV) in hard quasi-elastic two-body collisions involving a large momentum transfer to the H center. However, H - anions are preferentially emitted at low energy (eV) due to soft many-body (≥ 2) collisions resulting in a low momentum transfer. The formation of H - ions by electron capture follows excitation or ionization of the molecule. The molecular fragmentation dynamics is modeled to simulate the emission of H - ions. The overall good agreement between the simulation and the experiment leads to the understanding of most of the experimental observations. (author) [fr

  4. Strategies for public health initiatives targeting dairy consumption in young children: a qualitative formative investigation of parent perceptions.

    Science.gov (United States)

    Jung, Mary E; Bourne, Jessica E; Buchholz, Andrea; Martin Ginis, Kathleen A

    2017-11-01

    Dairy products contain essential nutrients to ensure healthy growth and bone development in children. However, a significant proportion of children in developed countries fail to consume the daily recommended intake of dairy products. Parents are the gatekeepers of familial nutritional intake and represent a potential vehicle through which to increase dairy consumption in children. As such, formative research was conducted to gain insight into parents' perceived barriers to and benefits of purchasing and consuming dairy products and to develop innovative message content that could be utilized in future public health campaigns. Seven in-depth group interviews were conducted in two phases between February and May 2015. Interviews were conducted in local recreational centres and libraries in British Columbia, Canada. Mothers (n 21, mean age 38 (sd 5) years) and fathers (n 9, mean age 38 (sd 3) years) of children aged 4-10 years. Parents perceived both positive and negative physical outcomes associated with consuming dairy. Lack of trustworthy information was a frequently discussed barrier theme to purchasing and consuming dairy products. Mothers were concerned about the cost of dairy products. Differences in purchasing and consumption strategies were reported between parents of children who consumed adequate dairy and those who did not. Parents believed the most appropriate communication channel was through print material. Messages targeting parents, as a means of increasing dairy consumption in children, should address barriers identified by parents. In addition, practical tips should be provided to promote purchasing and consumption of dairy products.

  5. Cholesterol-lowering drug, in combination with chromium chloride ...

    Indian Academy of Sciences (India)

    Lovastatin, being an inhibitor of HMG-CoA-Reductase, inhibitsinfection by cholesterol depletion, while chromium chloride complexes, at their higher concentrations, are reported toexhibit cytotoxicity. In intracellular amastigotes, cytotoxicity has been checked by assessing various manifestation of celldeath, viz.

  6. Arsenic, chromium, copper, iron, manganese, lead, selenium and ...

    African Journals Online (AJOL)

    Arsenic, chromium, copper, iron, manganese, lead, selenium and zinc in the tissues of the largemouth yellowfish, Labeobarbus kimberleyensis (Gilchrist and Thompson, 1913), from the Vaal Dam, South Africa, and associated consumption risks.

  7. Contingency plans for chromium utilization. Publication NMAB-335

    International Nuclear Information System (INIS)

    1978-01-01

    The United States depends entirely on foreign sources for the critical material, chromium, making it very vulnerable to supply disruptions. This vulnerability results because chromium is essential for the fabrication of corrosion-resisting steels and high-temperature, oxidation-resisting alloys in applications that are vital to the nation's technological well-being; because no substitutes are known for these materials in those applications; and because the known, substantial deposits of chromite ore are only in a few geographical locations that could become inaccessible to the United States as a result of political actions. The effectiveness of programs such as stockpiling, conservation, and research and development for substitutes to reduce the impact of disruption of imports of chromite and ferrochromium are discussed. Alternatives for decreasing chromium consumption also are identified for chromium-containing materials in the areas of design, processing, and substitution

  8. Synthesis and spectral properties of Chromium(III) complex of ...

    African Journals Online (AJOL)

    ISSCH) with chromium(III) chloride. The complex was characterized by molar conductance, magnetic moment, infrared, far-infrared and electronic spectra and elemental analysis. The ligand exists in keto tantomeric form and it coordinates through ...

  9. IRIS Toxicological Review of Hexavalent Chromium (Peer Review Plan)

    Science.gov (United States)

    EPA is conducting a peer review of the scientific basis supporting the human health hazard and dose-response assessment of hexavalent chromium that will appear on the Integrated Risk Information System (IRIS) database.

  10. Molecular Mechanisms of Chromium in Alleviating Insulin Resistance

    Science.gov (United States)

    Hua, Yinan; Clark, Suzanne; Ren, Jun; Sreejayan, Nair

    2011-01-01

    Type 2 diabetes is often associated with obesity, dyslipidemia, and cardiovascular anomalies and is a major health problem approaching global epidemic proportions. Insulin resistance, a prediabetic condition, precedes the onset of frank type 2 diabetes and offers potential avenues for early intervention to treat the disease. Although lifestyle modifications and exercise can reduce the incidence of diabetes, compliance has proved to be difficult, warranting pharmacological interventions. However, most of the currently available drugs that improve insulin sensitivity have adverse effects. Therefore, attractive strategies to alleviate insulin resistance include dietary supplements. One such supplement is chromium, which has been shown reduce insulin resistance in some, but not all, studies. Furthermore, the molecular mechanisms of chromium in alleviating insulin resistance remain elusive. This review examines emerging reports on the effect of chromium, as well as molecular and cellular mechanisms by which chromium may provide beneficial effects in alleviating insulin resistance. PMID:22423897

  11. Mössbauer and magnetization studies of nanosize chromium ferrite

    African Journals Online (AJOL)

    user

    ray diffraction (XRD), vibrating sample magnetometer (VSM) and Mössbauer spectroscopic techniques. Synthesized chromium ferrite powders were in good phase and showed spinel structure in the XRD pattern. Nanocrystalline CrF powder ...

  12. Study of effect of chromium on titanium dioxide phase transformation ...

    Indian Academy of Sciences (India)

    Administrator

    Electronic Supplementary Material. Study of effect of chromium on titanium dioxide phase transformation by A Bellifa (pp 669–677). Figure S1. Structural schemes of anatase to rutile transition. Figure S2. Analysis ATG-ATD for different samples.

  13. Stabilization of chromium salt in ordinary portland cement

    Indian Academy of Sciences (India)

    Keywords. Stabilization/solidification; ordinary portland cement; ammonium dichromate; differential microcalorimetry; conductometry;. Fourier transform infrared spectroscopy. 1. Introduction. The stabilization/solidification process of the chromium wastes generated from steel production, chrome plating, pigments and leather ...

  14. Recovery of Chromium (III) from Tannery wastewater | ALI AWAN ...

    African Journals Online (AJOL)

    Three aqueous oxidants, Hydrogen peroxide, Sodium Hypochlorite and Calcium Hypochlorite were employed independently in oxidizing Chromium (III) containing tannery wastewaters to soluble chromate (CrO42-) under alkaline conditions. The amount of chromate recovered was determined via spectrophotometry.

  15. Fabrication of high rate chromium getter sources for fusion applications

    International Nuclear Information System (INIS)

    Gabbard, W.A.; Simpkins, J.E.; Mioduszewski, P.; Edmonds, P.H.

    1983-01-01

    Design and fabrication techniques are described for the manufacture of large-capacity chromium getter sources, analogous to the commercially available titanium getter source known as Ti-Ball, manufactured by Varian Associates

  16. Composite Coatings of Chromium and Nanodiamond Particles on Steel

    Directory of Open Access Journals (Sweden)

    Gidikova N.

    2017-12-01

    Full Text Available Chrome plating is used to improve the properties of metal surfaces like hardness, corrosion resistance and wear resistance in machine building. To further improve these properties, an electrodeposited chromium coating on steel, modified with nanodiamond particles is proposed. The nanodiamond particles (average size 4 nm measured by TEM are produced by detonation synthesis (NDDS. The composite coating (Cr+NDDS has an increased thickness, about two times greater microhardness and finer micro-structure compared to that of unmodified chromium coating obtained under the same galvanization conditions. In the microstructure of specimen obtained from chrome electrolyte with concentration of NDDS 25 g/l or more, “minisections” with chromium shell were found. They were identified by metallographic microscope and X-ray analyser on etched section of chromium plated sample. The object of further research is the dependence of the presence of NDDS in the composite coating from the nanodiamond particles concentration in the chroming electrolyte.

  17. Determination of Wastewater Acids from Chromium Plating and Electropolishing Solutions

    National Research Council Canada - National Science Library

    Sopok, Samuel

    1995-01-01

    ... Laboratories vessel plating program. The chemical literature provides offline laboratory detection of chromic acid from chromium plating wastewater solutions, as well as phosphoric and sulfuric acids from electropolishing wastewater solutions...

  18. Removal of Hexavalent Chromium from Aqueous Solutions Using Magnetic Nanoparticles Coated with Alumina and Modified by Cetyl Trimethyl Ammonium Bromide

    Directory of Open Access Journals (Sweden)

    Mohammad Malakootian

    2015-12-01

    Full Text Available Introduction: The development of an effective method regarding chromium removal from the environment is of great importance. Therefore, the present study aimed to examiner magnetic nanoparticles coated with alumina modified by Cetyl Trimethyl Ammonium Bromide (CTAB in the removal of Cr6+ through magnetic solid phase extraction method. Materials & Methods: At first, iron oxide nanoparticles were synthesized, coated with alumina, modified with CTAB and characterized with suitable instruments. The factors affecting the process of chromium removal were investigated, including the concentration of CTAB, the pH, the amount of nanoparticles, the sample volume, a proper eluent, the adsorption and desorption time, and the effect of interfering ions. Moreover, the chromium concentration was determined by flame atomic absorption spectrometric (FAAS technique. The adsorption isotherm, adsorption capacity, and recoverability of the adsorbent were further examined. Results: The modified magnetic nanoparticles were demonstrated to be homogeneous, spherical, with a size lower than 20 nanometer having a magnetic property. The optimal conditions for chromium removal entailed 7*10-6 mol/L concentration of CTAB, pH range of 6-8, 0.1 g of the nanoparticles, 10 mL volume of the chromium sample (5 &mug mL-1, nitric acid 2 M as a suitable eluent, 15 minutes of adsorption and desorption, and no interference of interfering ions in the process of chromium separation. The process efficiency under optimal conditions was determined to be over 95%, which this process followed the Langmuir adsorption isotherm. The adsorption capacity proved to be 23.8 mg/g. Reusing after four times of adsorbent recovering was effective in the chromium removal (80%. The method accuracy for five measurement times was 4.155% and the method’s LOD was 0.081 mg/L. Conclusion: The method enjoys the benefits of convenient preparation of the adsorbent, high selectivity, high accuracy, short process

  19. Pengaruh konsentrasi cobalt chromium pada uji hemolisis sebagai implan gigi

    Directory of Open Access Journals (Sweden)

    Yosaphat Bayu Rosanto

    2016-12-01

    Full Text Available The effect of concentration of cobalt chromium in hemolysis test for dental implant. Dental implants are used to replace tooth/teeth loss and its function. Cobalt chromium has ideal characteristics to be made as dental implants material. It is required that the material to be implanted must be biocompatible with cells and tissues. One of biocompatibility characteristics is hemocompatibility. Hemocompatibility of materials can be observed with hemolysis test. Thus the purpose of this research is to know whether cobalt chromium as dental implants material affect the hemolysis of rabbit blood or not. This research was done with rabbit blood (Oryctolagus cuniculus and devided into 3 groups (treatment, positive and negative control. The tested material was cobalt chromium Remanium® GM 800, a product from Dentaurum. The contact between blood and material was done with ASTM-F075 hemolysis test. Cobalt chromium was not hemolytic at 2,5%, 5%, and 10% of concentration, slightly hemolytic at 20% of concentration, and hemolytic at 40% and 80% of concentration. The conclusion of this research was variety of concentration of cobalt chromium affected hemolysis percentage signi cantly. ABSTRAK Implan gigi digunakan untuk mengganti gigi yang hilang untuk dan dapat mengembalikan fungsi gigi. Cobalt chromium memiliki sifat-sifat yang memenuhi persyaratan sebagai material implan. Material yang diimplankan dalam tubuh harus memiliki sifat biokompatibilitas. Salah satu sifat biokompatibilitas yang harus dimiliki material yang diimplankan dalam tubuh adalah sifat hemokompatibilitas. Sifat hemokompatibilitas dapat diketahui dengan uji hemolisis. Penelitian ini bertujuan untuk mengetahui ada/tidaknya pengaruh logam cobalt chromium sebagai material implan gigi terhadap hemolisis pada darah kelinci. Penelitian ini dilakukan menggunakan sampel darah yang didapat dari kelinci (Oryctolagus cuniculus yang dibagi menjadi 3 kelompok, yaitu perlakuan, kontrol

  20. Investigating the non-linearity of the BOLD cerebrovascular reactivity response to targeted hypo/hypercapnia at 7T.

    Science.gov (United States)

    Bhogal, Alex A; Siero, Jeroen C W; Fisher, Joseph A; Froeling, Martijn; Luijten, Peter; Philippens, Marielle; Hoogduin, Hans

    2014-09-01

    Cerebrovascular reactivity (CVR) is a mechanism responsible for maintaining stable perfusion pressure within the brain via smooth muscle mediated modulations of vascular tone. The amplitude of cerebral blood flow (CBF) change in response to a stimulus has been evaluated using Blood Oxygen Level Dependent (BOLD) MRI, however the relationship between the stimulus and the measured signal remains unclear. CVR measured invasively in animal models and using blood-velocity based measurements in humans has demonstrated a sigmoidal relationship between cerebral blood flow and CO2 partial pressure. Using an ultra-high magnetic field strength (7T) MRI scanner and a computer controlled gas delivery system, we examined the regional and voxel-wise CVR response in relation to a targeted progressively increasing hypo- to hypercapnic stimulus. The aim of this study was to assess the non-linearity/sigmoidal behavior of the CVR response at varying arterial CO2 (PaCO2) levels. We find that a sigmoidal model provides a better description of the BOLD signal response to increasing PaCO2 than a linear model. A distinct whole-brain and gray matter BOLD-CVR signal plateau was observed in both voxel-wise and regional analysis. Furthermore, we demonstrate that a progressively increasing stimulus in combination with a sigmoidal response model can be used to obtain CVR values and provides additional physiologically relevant information (such as linear and non-linear response domains, and maximum response amplitudes) that may be more difficult to obtain from blocked CVR experiments. Considering these results, we propose an alternative way in which to define CVR based on the derivative of the BOLD-CVR response curve, which can potentially be used to differentiate between healthy and diseased vascular states. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Stereology of carbide phase in modified hypereutectic chromium cast iron

    Directory of Open Access Journals (Sweden)

    J. Suchoń

    2010-04-01

    Full Text Available In paper are presented results of studies of carbide phase stereology modified hypereutectic wear resistance chromium cast iron which contains carbon about 3,5% and chromium about 25%. Three substances were applied to the modification: boron carbide (B4C, ferroniobium (FeNb and mixture of ferroniobium and rare-earth (RE. The measurements of geometrical features of carbides were conducted on microsection taken from castings wich were cooled with various velocities.

  2. SCIENCE AND TECHNOLOGY ACTIVITIES FOR CHROMIUM IN THE 100 AREAS

    Energy Technology Data Exchange (ETDEWEB)

    PETERSEN SW

    2009-07-02

    {sm_bullet} Primary Objective: Protect the Columbia River - Focus is control and treatment of contamination at or near the shoreline, which is influenced by bank storage {sm_bullet} Secondary Objective: Reduce hexavalent chromium to <48 parts per billion (ppb) in aquifer (drinking water standard) - Large plumes with isolated areas of high chromium concentrations (> 40,000 ppb), - Unknown source location(s); probably originating in reactor operation areas

  3. Chromium (V) compounds as cathode material in electrochemical power sources

    Science.gov (United States)

    Delnick, F.M.; Guidotti, R.A.; McCarthy, D.K.

    A cathode for use in a thermal battery, comprising a chromium (V) compound. The preferred materials for this use are Ca/sub 5/(CrO/sub 4/)/sub 3/Cl, Ca/sub 5/(CrO/sub 4/)OH, and Cr/sub 2/O/sub 5/. The chromium (V) compound can be employed as a cathode material in ambient temperature batteries when blended with a suitably conductive filler, preferably carbon black.

  4. Method for heat treating iron-nickel-chromium alloys

    International Nuclear Information System (INIS)

    Merrick, H.F.; Korenko, M.K.

    1981-01-01

    A method is specified for heat treating age-hardenable iron-nickel-chromium alloys to obtain a morphology of the gamma-double prime phase enveloping the gamma-prime, the alloy consisting essentially of from 25% to 45% nickel, 10% to 16% chromium, 1.5% to 3% of molybdenum or niobium, about 2% titanium, about 3% aluminum, and the remainder substantially all iron. (author)

  5. Chromium Ions Improve Moisure Resistance of Epoxy Resins

    Science.gov (United States)

    St. Clair, A. K.; St. Clair, T. L.; Stoakley, D. M.; Singh, J. J.; Sprinkle, D. R.

    1986-01-01

    Broad spectrum of thermosetting epoxy resins used on commercial and military aircraft, primarily as composite matrices and adhesives. In new technique, chromium-ion containing epoxy with improved resistance to moisture produced where chromium ions believed to prevent absorption of water molecules by coordinating themselves to hydroxyl groups on epoxy chain. Anticipated that improved epoxy formulation useful as composite matrix resin, adhesive, or casting resin for applications on commercial and advanced aircraft. Improvement made without sacrifice in mechanical properties of polymer.

  6. The suppression of dissolution for alloy 690 in high temperature and high pressure water with chromium ion implantation

    International Nuclear Information System (INIS)

    Shibata, Toshio; Fujimoto, Shinji; Ohtani, Saburou; Watanabe, Masanori; Hirao, Kyozo; Okumoto, Masaru; Shibaike, Hiroyuki.

    1994-01-01

    As the material of heat exchanger tubes for PWRs, the nickel alloys such as alloy 690 and alloy 600 have been used, but 58 Ni and 60 Co contained as an impurity elute in primary cooling water, and are radioactivated, in this way, they become the cause of radiation exposure. By increasing chromium concentration, the corrosion resistance of nickel alloys is improved, and for modern heat exchangers, the alloy 690, of which the chromium content is increased up to 30%, has been adopted, and excellent results have been obtained. In this research, aiming at the further reduction of radiation exposure, by increasing the chromium concentration in surface layer using ion implantation technology, the change of the corrosion behavior of alloy 690 in high temperature, high pressure water was investigated. The chemical composition of the alloy 690 used, and the making of plate specimens are shown. The polarization behavior of alloy 690 in 0.1 mol/l sulfuric acid deaerated at normal temperature is reported, and the effect of suppressing dissolution was remarkable in the specimens with much implantation. The electrochemical behavior of alloy 690 in simulated cooling water was investigated. Immobile case has high chromium content and is thin. (K.I.)

  7. In Silico Investigations of Chemical Constituents of Clerodendrum colebrookianum in the Anti-Hypertensive Drug Targets: ROCK, ACE, and PDE5.

    Science.gov (United States)

    Arya, Hemant; Syed, Safiulla Basha; Singh, Sorokhaibam Sureshkumar; Ampasala, Dinakar R; Coumar, Mohane Selvaraj

    2017-06-16

    Understanding the molecular mode of action of natural product is a key step for developing drugs from them. In this regard, this study is aimed to understand the molecular-level interactions of chemical constituents of Clerodendrum colebrookianum Walp., with anti-hypertensive drug targets using computational approaches. The plant has ethno-medicinal importance for the treatment of hypertension and reported to show activity against anti-hypertensive drug targets-Rho-associated coiled-coil protein kinase (ROCK), angiotensin-converting enzyme, and phosphodiesterase 5 (PDE5). Docking studies showed that three chemical constituents (acteoside, martinoside, and osmanthuside β6) out of 21 reported from the plant to interact with the anti-hypertensive drug targets with good glide score. In addition, they formed H-bond interactions with the key residues Met156/Met157 of ROCK I/ROCK II and Gln817 of PDE5. Further, molecular dynamics (MD) simulation of protein-ligand complexes suggest that H-bond interactions between acteoside/osmanthuside β6 and Met156/Met157 (ROCK I/ROCK II), acteoside and Gln817 (PDE5) were stable. The present investigation suggests that the anti-hypertensive activity of the plant is due to the interaction of acteoside and osmanthuside β6 with ROCK and PDE5 drug targets. The identified molecular mode of binding of the plant constituents could help to design new drugs to treat hypertension.

  8. Influence of chromium ions on the color center formation in crystals with garnet structure

    International Nuclear Information System (INIS)

    Ashurov, M.Kh.; Zharikov, E.V.; Laptev, V.V.

    1985-01-01

    The in fluence of chromium ions on the color center formation in crystals of yttrium-aluminium garnet, gadolinium-gallium garnet, gadolinium-scandium-gallium garnet, and yttrium-scandium-gallium garnet is studied. In addition to basic activator ions these crystals were coactivated also by chromium ions with two wide bands of fundamental absorption within the range of pump tube radiation with maximas close to 450 and 650 nm. The color centers for γ-irradiated samples were observed at 300 K by measuring the adsorption spectra within the 300-800 nm range. Temperature of destruction of the charge trapping sites was determined by the method of thermoluminescence measuring in the 100-500 K temperature range. Detection of recombination center luminescence was accomplished within the 200-1600 nm wavelength range. Chromium ions are found to hinder the formation of color centers as a result of γ-irradiation at room and higher temperatures within the wavelength range over 300 nm; i.e. Cr 3+ ions increase radiation resistance of all the investigated crystals

  9. Photoconductivity, photoluminescence and optical Kerr nonlinear effects in zinc oxide films containing chromium nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Torres, C., E-mail: crstorres@yahoo.com.mx [Seccion de Estudios de Posgrado e Investigacion, ESIME-Z, Instituto Politecnico Nacional, Mexico, DF 07738 (Mexico); Garcia-Cruz, M.L. [Centro de Investigacion en Dispositivos Semiconductores, Benemerita Universidad Autonoma de Puebla, A. P. J-48, Puebla 72570, Mexico (Mexico); Castaneda, L., E-mail: luisca@sirio.ifuap.buap.mx [Instituto de Fisica, Benemerita Universidad Autonoma de Puebla, A. P. J-48, Puebla 72570, Mexico (Mexico); Rangel Rojo, R. [CICESE/Depto. de Optica, A. P. 360, Ensenada, BC 22860 (Mexico); Tamayo-Rivera, L. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Mexico, DF 01000 (Mexico); Maldonado, A. [Depto. de Ing. Electrica, CINVESTAV IPN-SEES, A. P. 14740, Mexico DF 07000 (Mexico); Avendano-Alejo, M., E-mail: imax_aa@yahoo.com.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, A. P. 70-186, 04510, DF (Mexico); and others

    2012-04-15

    Chromium doped zinc oxide thin solid films were deposited on soda-lime glass substrates. The photoconductivity of the material and its influence on the optical behavior was evaluated. A non-alkoxide sol-gel synthesis approach was used for the preparation of the samples. An enhancement of the photoluminescence response exhibited by the resulting photoconductive films with embedded chromium nanoclusters is presented. The modification in the photoconduction induced by a 445 nm wavelength was measured and then associated with the participation of the optical absorptive response. In order to investigate the third order optical nonlinearities of the samples, a standard time-resolved Optical Kerr Gate configuration with 80 fs pulses at 830 nm was used and a quasi-instantaneous pure electronic nonlinearity without the contribution of nonlinear optical absorption was observed. We estimate that from the inclusion of Cr nanoclusters into the sample results a strong optical Kerr effect originated by quantum confinement. The large photoluminescence response and the important refractive nonlinearity of the photoconductive samples seem to promise potential applications for the development of multifunctional all-optical nanodevices. - Highlights: Black-Right-Pointing-Pointer Enhancement in photoluminescence for chromium doped zinc oxide films is presented. Black-Right-Pointing-Pointer A strong and ultrafast optical Kerr effect seems to result from quantum confinement. Black-Right-Pointing-Pointer Photoconductive properties for optical and optoelectronic functions were observed.

  10. Reliability of thickness of oxide layer of stainless steels with chromium using cellular automaton model

    International Nuclear Information System (INIS)

    Lan, K. C.; Chen, Y.; Yu, G. P.; Hung, T. C.

    2012-01-01

    A cellular automaton (CA) model based on the stochastic approach was proposed to simulate the process of oxidation and corrosion of stainless steels with different contents of chromium in-flowing lead bismuth eutectic (LBE). Chromium is a crucial alloying element added in stainless steels and nickel based alloys which have been proposed to be used in advanced nuclear reactors to improve resistance of the oxidation and corrosion. To verify the reliability of the thickness of the oxide layer by CA model, the influence of the stochastic character on the simulating results was investigated as changing parameter of chromium content of structure material in this study. Ten independent simulations were run for each specific environment. A stable and reasonable results were obtained according to the chi-square of goodness-of-fit test, the chi-square of the thickness of oxide layer for each case were significant smaller than critical chi-square value with a confidence level of 95% (Χ 2 α, v = Χ 2 0.05,9 = 16.92). (authors)

  11. Factors Affecting the Adsorption of Trivalent Chromium Ions by Activated Carbon Prepared from Waste Rubber Tyres

    Directory of Open Access Journals (Sweden)

    Sylvia E. Benjamin

    2017-08-01

    Full Text Available Economic gains are generally the outcome of industrialization and consequently urbanization. However, positive fiscal index generates a negative impact on natural environment sources heaving pollutant burden on soil, air and water. Industries throw tones of contaminated water into soil and water bodies without proper treatment and create a potential threat for both living and non-living species. Chromium in trivalent state (Cr3+ is added in water bodies and soil through waste water from tanneries, cooling water systems, chemical and pulp and paper industries. The present research work aims at the preparation of an inexpensive activated carbon prepared from non- degradable waste scrap rubber tyres. The carbon produced from scrap rubber tyres was activated by 5% solution of BaCl2 and 0.4 N solution of HCl and verified by ethylene blue solution. The adsorption capacity of the Tyre activated carbon (TAC was investigated for different parameters i.e., initial chromium (III ion concentration, activated carbon dosage, contact/ stirring time and pH. The adsorption capacity of TAC depends on the initial metal ion concentration and the TAC dose. pH of the chromium solution effects the adsorption capacity of TAC due to the formation of tetra hydroxochromate(III complexes,. The results show that TAC offers a cost effective reclamation process for the removal of Cr3+ from effluent waters.

  12. Hexavalent chromium removal from aqueous solutions by a novel powder prepared from Colocasia esculenta leaves.

    Science.gov (United States)

    Nakkeeran, E; Saranya, N; Giri Nandagopal, M S; Santhiagu, A; Selvaraju, N

    2016-08-02

    In this study, batch removal of hexavalent chromium from aqueous solutions by powdered Colocasia esculenta leaves was investigated. Batch experiments were conducted to study the effects of adsorption of Cr(VI) at different pH values, initial concentrations, agitation speeds, temperatures, and contact times. The biosorbent was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectrometer analysis. The biosorptive capacity of the adsorbent was dependent on the pH of the chromium solution in which maximum removal was observed at pH 2. The adsorption equilibrium data were evaluated for various adsorption isotherm models, kinetic models, and thermodynamics. The equilibrium data fitted well with Freundlich and Halsey models. The adsorption capacity calculated was 47.62 mg/g at pH 2. The adsorption kinetic data were best described by pseudo-second-order kinetic model. Thus, Colocasia esculenta leaves can be considered as one of the efficient and cheap biosorbents for hexavalent chromium removal from aqueous solutions.

  13. Comparison of chromium and nickel uptake of plants grown in different soils

    Energy Technology Data Exchange (ETDEWEB)

    Vago, I. [University of Agriculture, Faculty of Agronomy, H-4015 Debrecen, P.O. Box 36 (Hungary); Gyoeri, Z. [University of Agriculture, Faculty of Agronomy, H-4015 Debrecen, P.O. Box 36 (Hungary); Loch, J. [University of Agriculture, Faculty of Agronomy, H-4015 Debrecen, P.O. Box 36 (Hungary)

    1996-03-01

    The chromium and nickel uptake of ryegrass has been examined in pot experiments in extremely different soils, poor sandy and fertile black chernozem. The effect of calcium carbonate doses and nitrogen supply on heavy metal uptake of the plant has been studied for chromium and nickel loadings (0-100 mg/kg Cr{sup 3+} or Ni{sup 2+}) applied as inorganic salts. The ability to uptake Cr{sup 3+} and Ni{sup 2+} differs significantly and is highly affected by the characteristics of soils, and depends on the metal investigated. The heavy metal uptake of the plant differs significantly in acid, colloid deficient sandy soils; while artificial chromium contamination did not modify the dry-matter production in the pots in either soil, a large quantity of nickel reduced the yields significantly. Nitrogen application did not change significantly the uptake of heavy metals. Lime application reduced the Ni{sup 2+} uptake of plants considerably, especially in sandy soil. In case of a calcium carbonate addition the dry-matter production of the plant was not affected by nickel. In chernozem soil the effect of lime application - i.e., the reduction of nickel uptake - was of a lesser degree. The significantly lesser Cr{sup 3+} uptake was further limited by a calcium carbonate application for both soils studied. A graphic presentation of these effects is given. (orig.). With 3 figs., 3 tabs.

  14. Chromium exposure among children from an electronic waste recycling town of China.

    Science.gov (United States)

    Xu, Xijin; Yekeen, Taofeek Akangbe; Liu, Junxiao; Zhuang, Bingrong; Li, Weiqiu; Huo, Xia

    2015-02-01

    Guiyu is one of the most heavily chromium-polluted areas in China due to the numerous informal electronic waste (e-waste) recycling activities. A 3-year (2004, 2006, and 2008) independent cross-sectional study on blood chromium (BCr) levels of 711 children from Guiyu and a control area was investigated. Questionnaire completed by parents/guardians was used to assess the risk factors of chromium (Cr) exposure, while physical examination, for the year 2008 only, was used to evaluate the effects of long-term exposure to Cr on child physical development. Children living in Guiyu had significantly higher BCr levels compared with those living in Chendian at the same period from 2004 to 2008 (P e-waste recycling, and child residence in Guiyu. Children's weight and chest circumferences in group with high exposure to Cr (upper quartile) were higher than in the low-exposure group (P e-waste recycling activities might be threatening the health of children, with implications on physical growth and development.

  15. Relation of Nickel Allergy with in-Stent Restenosis in Patients Treated with Cobalt Chromium Stents.

    Science.gov (United States)

    Aliağaoğlu, Cihangir; Turan, Hakan; Erden, Ismail; Albayrak, Hülya; Ozhan, Hakan; Başar, Cengiz; Gürlevik, Zehra; Alçelik, Ayşegül

    2012-11-01

    In-stent restenosis (ISR) is the major limitation of percutaneous coronary stenting procedure. The elements like nickel, chromate and molybdenum are known to cause contact allergy. Hypersensitivity reaction, against these metal ions, may be one of the reasons of ISR. Cobalt chromium coronary stents, which are increasingly being used in percutaneous coronary interventions, have more nickel amount than the stainless steel stents. We aimed to investigate the association between nickel hypersensitivity reaction and ISR in patients treated with cobalt chromium coronary stents. Epicutaneous patch tests for nickel were applied to 31 patients who had undergone elective cobalt chromium coronary stent implantation and had ISR in control angiogram. Thirty patients, without ISR, were included as the control group. Patch test results and other clinical variables were compared. There was no statistically significant difference of the mean age, sex, body mass index, rate of hypercholesterolemia, diabetes, hypertension and smoking between the patients with and without ISR. All other lesion characteristics were similar in the 2 groups. According to the patch test results, 7 patients had nickel contact allergy. All of these patients were in the ISR group, which was statistically significant (pnickel allergy than the control group. Nickel allergy may play role in restenosis pathophysiology.

  16. Sliding wear studies of sprayed chromium carbide-nichrome coatings for gas-cooled reactor applications

    International Nuclear Information System (INIS)

    Li, C.C.; Lai, G.Y.

    1978-09-01

    Chromium carbide-nichrome coatings being considered for wear protection of some critical components in high-temperature gas-cooled reactors (HTGR's) were investigated. The coatings were deposited either by the detonation gun or the plasma-arc process. Sliding wear tests were conducted on specimens in a button-on-plate arrangement with sliding velocities of 7.1 x 10 -3 and 7.9 mm/s at 816 0 C in a helium environment simulates HTGR primary coolant chemistry. The coatings containing 75 or 80 wt % chromium carbide exhibited excellent wear resistance. As the chromium carbide content decreased from either 80 or 75 to 55 wt %, with a concurrent decrease in coating hardness, wear-resistance deteriorated. The friction and wear behavior of the soft coating was similar to that of the bare metal--showing severe galling and significant amounts of wear debris. The friction characteristics of the hard coating exhibited a strong velocity dependence with high friction coefficients in low sliding velocity tests ad vice versa. Both the soft coating and bare metal showed no dependence on sliding velocity. The wear behavior observed in this study is of adhesive type, and the wear damage is believed to be controlled primarily by the delamination process

  17. Accumulation and tolerance characteristics of chromium in a cordgrass Cr-hyperaccumulator, Spartina argentinensis

    Energy Technology Data Exchange (ETDEWEB)

    Redondo-Gomez, Susana, E-mail: susana@us.es [Departamento de Biologia Vegetal y Ecologia, Facultad de Biologia, Universidad de Sevilla, Apartado 1095, 41080 Sevilla (Spain); Mateos-Naranjo, Enrique; Vecino-Bueno, Inmaculada [Departamento de Biologia Vegetal y Ecologia, Facultad de Biologia, Universidad de Sevilla, Apartado 1095, 41080 Sevilla (Spain); Feldman, Susana R. [Biologia, Facultad de Ciencias Agrarias y CIUNR, Universidad Nacional de Rosario (Spain)

    2011-01-30

    The cordgrass Spartina argentinensis, which occurs in inland marshes of the Chaco-Pampean regions of Argentina, has been found to be a new chromium hyperaccumulator. A glasshouse experiment was designed to investigate the effect of Cr{sup 6+} from 0 to 20 mmol l{sup -1} on growth and photosynthetic apparatus of S. argentinensis by measuring chlorophyll fluorescence parameters, gas exchange and photosynthetic pigment concentrations. Boron, calcium, chromium, copper, iron, manganese, magnesium, potassium and phosphorous concentrations were also determined. S. argentinensis showed phytotoxicity at tiller concentration of 4 mg g{sup -1} Cr, and symptoms of stress at tiller concentration of 1.5 mg g{sup -1} Cr, as well as reductions in leaf gas exchange, in chlorophyll a fluorescence parameters, in photosynthetic pigment contents and in the uptake of essential nutrients. Reductions in net photosynthetic rate could be accounted for by non-stomatal limitations. Moreover, the bioaccumulator factors exceeded greatly the critical value (1.0) for all Cr treatments, and the transport factors indicated that this species has a higher ability to transfer Cr from roots to tillers at higher Cr concentrations. These results confirmed that S. argentinensis is a chromium hyperaccumulator and that it may be useful for restoring Cr-contaminated sites.

  18. 40 CFR Appendix Xii to Part 266 - Nickel or Chromium-Bearing Materials that may be Processed in Exempt Nickel-Chromium Recovery...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Nickel or Chromium-Bearing Materials that may be Processed in Exempt Nickel-Chromium Recovery Furnaces XII Appendix XII to Part 266... FACILITIES Pt. 266, App. XII Appendix XII to Part 266—Nickel or Chromium-Bearing Materials that may be...

  19. Stabilization of carbon dioxide and chromium slag via carbonation.

    Science.gov (United States)

    Wu, Xingxing; Yu, Binbin; Xu, Wei; Fan, Zheng; Wu, Zucheng; Zhang, Huimin

    2017-08-01

    As the main greenhouse gas, CO 2 is considered as a threat in the context of global warming. Many available technologies to reduce CO 2 emission was about CO 2 separation from coal combustion and geological sequestration. However, how to deal with the cost-effective storage of CO 2 has become a new challenge. Moreover, chromium pollution, the treatment of which requires huge energy consumption, has attracted people's widespread attention. This study is aimed to develop the sequestration of CO 2 via chromium slag. A dynamic leaching experiment of chromium slag was designed to testify the ability of CO 2 adsorption onto chromium slag and to release Cr(VI) for stabilization. The results showed that the accumulative amounts of Cr(VI) were ca. 2.6 mg/g released from the chromium slag after 24 h of leaching. In addition, ca. 89 mg/g CO 2 was adsorbed by using pure CO 2 in the experiment at 12 h. Calcite is the only carbonate species in the post-carbonated slag analyzed by powder X-ray diffraction and thermal analysis. The approach provides the feasibility of the utilization of chromium slag and sequestration of the carbon dioxide at the same time at ordinary temperatures and pressures.

  20. Cytokine detection for the diagnosis of chromium allergy*

    Science.gov (United States)

    Martins, Luis Eduardo Agner Machado; dos Reis, Vitor Manoel Silva

    2013-01-01

    BACKGROUND Patch testing remains the gold standard method for the identification of the etiologic agent of allergic contact dermatitis. However, it is a subjective, time-consuming exam whose technique demands special care and which presents some contraindications, which hamper its use. In a recent study, we showed that the proliferation assay can suitably replace patch testing for the diagnosis of chromium allergy, which had been previously demonstrated only for nickel allergy. In this study, we try to refine the method by reducing the incubation period of cultures for lymphocyte proliferation assays in response to chromium. OBJECTIVE Develop an alternative or complementary diagnostic test for chromium allergic contact dermatitis. METHODS We compared the production of 9 cytokines (IFN-γ, IL-2, IL-4, IL-5, IL-10, IL-12, IL-13, IL-17 and RANTES) between 18 chromium-allergic patients and 19 controls. RESULTS Chromium increased the production of IFN-y, IL-5, IL-2 and IL-13 in allergic patients, but only IL-2 and especially IL-13 helped discriminate allergic patients from controls. The sensitivity, specificity and accuracy found with IL-13 were about 80%. CONCLUSIONS IL-13 and IL-2 detection may be used to diagnose chromium allergy in 2-day cultures. However, in general, the 6-day cultures seem to be superior for this purpose. PMID:24173176

  1. Removal of Chromium and Lead from Industrial Wastewater Using

    Directory of Open Access Journals (Sweden)

    Mohamed Hilal

    2013-04-01

    Full Text Available In this research an attempt is made on the ability of aerobic treatment of synthetic solutions containing lead and chromium using effective microorganisms within the reactor. To achieve the desired objectives of the research, synthetic aqueous solutions of lead and chromium was used in the concentration of chromium and lead ions of 5, 10,50 and 100 mg / l .The work was done at constant pH equal to 4.5 and temperature of 30 ± 1 º C. Effective microorganisms solutions was added to the reactor at Vol.% of 1/50 ,1/100 ,1/500 and 1/1000, with retention time was 24 hours to measure the heavy metals concentration the atomic absorption device was used. The experimental results showed that each 1mg / l of lead and chromium ions need 24 mg of effective microorganisms to achieve removal of 92.0% and 82.60% for lead and chromium respectively. Increasing the concentration of effective microorganisms increases the surface of adsorption and thus increasing the removal efficiency. It is found that the microorganisms activity occur in the first five hours of processing and about 94% of adsorption capacity of biomass will take place. It is also found the selectivity of microorganisms to lead ions is higher than for chromium ions.

  2. Cobalt, nickel and chromium release from dental tools and alloys.

    Science.gov (United States)

    Kettelarij, Jolinde A B; Lidén, Carola; Axén, Emmy; Julander, Anneli

    2014-01-01

    Cobalt-chromium alloys are used as casting alloys by dental technicians when producing dental prostheses and implants. Skin exposure and metal release from alloys and tools used by the dental technicians have not been studied previously. To study the release of cobalt, nickel and chromium from alloys and tools that come into contact with the skin of dental technicians. Cobalt and nickel release from tools and alloys was tested with the cobalt spot test and the dimethylglyoxime test for nickel. Also, the release of cobalt, nickel and chromium in artificial sweat (EN1811) at different time-points was assessed. Analysis was performed with inductively coupled plasma-mass spectrometry. Sixty-one tools were spot tested; 20% released nickel and 23% released cobalt. Twenty-one tools and five dental alloys were immersed in artificial sweat. All tools released cobalt, nickel and chromium. The ranges were 0.0047-820, 0.0051-10 and 0.010-160 µg/cm(2) /week for cobalt, nickel and chromium, respectively. All dental alloys released cobalt in artificial sweat, with a range of 0.0010-17 µg/cm(2) /week, and they also released nickel and chromium at low concentrations. Sensitizing metals are released from tools and alloys used by dental technicians. This may cause contact allergy and hand eczema. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Using voltage-sensor toxins and their molecular targets to investigate NaV1.8 gating.

    Science.gov (United States)

    Gilchrist, John; Bosmans, Frank

    2017-11-29

    Voltage-gated sodium (Na V ) channel gating is a complex phenomenon which involves a distinct contribution of four integral voltage-sensing domains (VSDI, VSDII, VSDIII and VSDIV). Utilizing accrued pharmacological and structural insights, we build on an established chimera approach to introduce animal toxin sensitivity in each VSD of an acceptor channel by transferring in portable S3b-S4 motifs from the four VSDs of a toxin-susceptible donor channel (Na V 1.2). By doing so, we observe that in Na V 1.8, a relatively unexplored channel subtype with distinctly slow gating kinetics, VSDI-III participate in channel opening whereas VSDIV can regulate opening as well as fast inactivation. These results illustrate the effectiveness of a pharmacological approach to investigate the mechanism underlying gating of a mammalian Na V channel complex. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

  4. Using of the Boolean Stochastic Generation method to target field investigations: the Mortisa landslide (eastern Italian Alps) case study

    Science.gov (United States)

    Bossi, Giulia; Marcato, Gianluca; Gottardi, Guido; Borgatti, Lisa

    2016-04-01

    When designing the geotechnical model of a landslide the information to define the soil profile within the slope is usually inferred from a small amount of data. This is particularly true for large landslides where the study area is vast and the variability of terrains is high. In this framework, a method allowing the best locations for further field investigation campaigns to be identified would be extremely useful. The Boolean Stochastic Generation method (BoSG), which randomly generates different soil distributions of two definite soil types in both 2D and 3D models, is a newly developed algorithm that can guide in this process. In this work the method has been applied to the Mortisa landslide case study, which is located in the Cortina d'Ampezzo valley (Veneto, Italy), part of the Dolomites UNESCO World Heritage list. The mudslide is 3.5 km long, stretching from 1750 to 1300 m a.s.l., and is located in a highly antrophized area where is damaging some buildings and a national road with its almost continuous movements. In fact, from year 2008, GNSS surveys recorded rates of displacements reaching 1.2 m/year in the most active parts of the landslide; the movements occur on a slip surfaces are located between 20 and 50 m below the surface. From the borecores some wooden samples were extracted allowing to reconstruct the sequence of events that led to the development of the present-day Mortisa slope. Interdigitated layers of gravel in a silty clay matrix originated from subsequent earth and debris flows events since the Lateglacial compose the landslide body, a condition that is particularly apt to be investigated with BoSG. A BoSG run for the Mortisa landslide was performed calculating 1200 soil configurations and using laboratory test parameters for the silty-clay matrix. The results were stacked in a tridimensional matrix in order to calculate the mean and the standard deviation (SD) of displacements for each element of the model mesh. In this way maps of the SD

  5. Experimental skin deposition of chromium on the hands following handling of samples of leather and metal

    DEFF Research Database (Denmark)

    Bregnbak, David; Thyssen, Jacob P.; Jellesen, Morten Stendahl

    2016-01-01

    Background: Chromium is an important skin sensitizer. Exposure to it has been regulated in cement, and recently in leather. Studies on the deposition of chromium ions on the skin as a result of handling different chromium-containing materials are sparse, but could improve the risk assessment...... of contact sensitization and allergic contact dermatitis caused by chromium. Objectives: To determine whether the handling of chromium-containing samples of leather and metal results in the deposition of chromium onto the skin. Methods: Five healthy volunteers participated. For 30 min, they handled samples...... of leather and metal known to contain and release chromium. Skin deposition of chromium was assessed with the acid wipe sampling technique. Results: Acid wipe sampling of the participants' fingers showed chromium deposition on the skin in all participants who had been exposed to leather (range 0.01–0.20 µg...

  6. Coupling of Nanoporous Chromium, Aluminium-Containing Silicates with an Ionic Liquid for the Transformation of Glucose into 5-(Hydroxymethyl-2-furaldehyde

    Directory of Open Access Journals (Sweden)

    Anabela A. Valente

    2012-03-01

    Full Text Available Micro/mesoporous chromium, aluminium-containing silicates of the type TUD-1 (Al-TUD-1, Cr-TUD-1, CrAl-TUD-1 and zeolite BEA, Cr-BEA, and related composites BEA/TUD-1 and Cr-BEA/TUD-1, were prepared, characterised, and tested as solid acids coupled with the ionic liquid (IL 1-butyl-3-methylimidazolium chloride ([bmim]Cl as solvent, in the transformation of d-glucose into 5-(hydroxymethyl-2-furaldehyde (Hmf, at 120 °C. The chromium-containing catalytic systems lead to considerably higher Hmf yields in comparison to the related systems without chromium. The IL is a favourable solvent for this target reaction (in terms of Hmf yields reached compared to water or dimethylsulfoxide. A detailed study on the stabilities of the nanoporous solid acids in the IL medium is presented.

  7. Chromium, CLA, and ractopamine for finishing pigs.

    Science.gov (United States)

    Marcolla, C S; Holanda, D M; Ferreira, S V; Rocha, G C; Serão, N V L; Duarte, M S; Abreu, M L T; Saraiva, A

    2017-10-01

    This study aimed to evaluate the effects of dietary chromium, CLA, and ractopamine on performance, carcass traits, and pork quality of finishing pigs slaughtered at 115 kg BW. Ninety-six crossbred barrows (initial BW = 70.21 ± 1.98 kg) were randomly assigned to 1 of 6 dietary treatments. There were 8 replicates per treatment (48 pens; 2 pigs/pen). A diet formulated according to the nutritional requirements was used as the control (CON). The other 5 diets were based on the CON and supplemented as follows: 0.4 mg/kg Cr yeast (CrY); 0.5% CLA; 0.4 mg/kg CrY and 0.5% CLA (CrY + CLA); 20 mg/kg ractopamine (RAC); 0.4 mg/kg CrY and 20 mg/kg RAC (CrY + RAC). Lysine levels on diets containing ractopamine were raised by 20% compared to CON to meet the greater requirements of pigs fed ractopamine. Pigs fed RAC and CrY + RAC were fed CON for the first 17 d, and then the respective diets for the last 28 d on trial. Data were analyzed in a model including the fixed effect of treatment (6 levels) and initial BW as a covariate for all characteristics, with the exception of carcass traits, in which final BW was used as a covariate. Least-squares means were separated using Tukey-Kramer's method. Differences were considered when probability values were lower than 0.05. Pigs fed RAC and CrY + RAC had the greatest ( 0.05) pork quality, except for color. No differences ( > 0.05) were observed for carcasses pH and temperature. The values for pigs fed RAC were greater ( = 0.01) than pigs fed other diets. Pigs fed RAC had lower ( < 0.01) values compared to pigs fed other experimental diets. Serum urea nitrogen concentration (SUN) was lower ( = 0.02) in pigs fed CrY + RAC than in pigs fed CON and RAC and similar to pigs fed the other feeding additives. In summary, it was demonstrated that, when combined, CrY and RAC increase LM area and carcass yield, and reduce SUN, suggesting that chromium could improve nutrient utilization by muscle cells in RAC-fed pigs. Additionally, the additives have

  8. Investigation of mixed ion fields in the forward direction for 220.5 MeV/u helium ion beams: comparison between water and PMMA targets

    Science.gov (United States)

    Aricò, G.; Gehrke, T.; Jakubek, J.; Gallas, R.; Berke, S.; Jäkel, O.; Mairani, A.; Ferrari, A.; Martišíková, M.

    2017-10-01

    Currently there is a rising interest in helium ion beams for radiotherapy. For benchmarking of the physical beam models used in treatment planning, there is a need for experimental data on the composition and spatial distribution of mixed ion fields. Of particular interest are the attenuation of the primary helium ion fluence and the build-up of secondary hydrogen ions due to nuclear interactions. The aim of this work was to provide such data with an enhanced precision. Moreover, the validity and limits of the mixed ion field equivalence between water and PMMA targets were investigated. Experiments with a 220.5 MeV/u helium ion pencil beam were performed at the Heidelberg Ion-Beam Therapy Center in Germany. The compact detection system used for ion tracking and identification was solely based on Timepix position-sensitive semiconductor detectors. In comparison to standard techniques, this system is two orders of magnitude smaller, and provides higher precision and flexibility. The numbers of outgoing helium and hydrogen ions per primary helium ion as well as the lateral particle distributions were quantitatively investigated in the forward direction behind water and PMMA targets with 5.2-18 cm water equivalent thickness (WET). Comparing water and PMMA targets with the same WET, we found that significant differences in the amount of outgoing helium and hydrogen ions and in the lateral particle distributions arise for target thicknesses above 10 cm WET. The experimental results concerning hydrogen ions emerging from the targets were reproduced reasonably well by Monte Carlo simulations using the FLUKA code. Concerning the amount of outgoing helium ions, significant differences of 3-15% were found between experiments and simulations. We conclude that if PMMA is used in place of water in dosimetry, differences in the dose distributions could arise close to the edges of the field, in particular for deep seated targets. The results presented in this publication are

  9. An in situ study of growth of Lemongrass Cymbopogon flexuosus (Nees ex Steud.) W. Watson on varying concentration of Chromium (Cr+6) on soil and its bioaccumulation: Perspectives on phytoremediation potential and phytostabilisation of chromium toxicity.

    Science.gov (United States)

    Patra, Deepak Kumar; Pradhan, Chinmay; Patra, Hemanta Kumar

    2018-02-01

    Chromium (Cr) contamination in soil is a growing concern in sustainable agricultural production and food safety. Remediation of Cr from contaminated soils is a challenging task which may not only help in sustaining agriculture but also in minimizing adverse environmental impacts. Pot culture experiments were performed with the application of varied concentration of Cr +6 to assess the Chromium accumulation potential of Lemongrass and to study the impact of toxic concentration of Cr +6 on morphological, physiological and biochemical parameters of the plant. The results showed an increasing accumulation trend of Chromium with increasing Chromium concentrations in both root and shoot of 60 days old Lemongrass plants, while the protein and chlorophyll contents decreased. Similarly, accumulation of Cr increased the levels of proline and antioxidant enzymes indicating the enhanced damage control activity. The potentiality of the plant with the capacity to accumulate and stabilize Cr compound in Cr contaminated soil by phytoremediation process has been explored in the present investigation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Determination of oral uptake and biodistribution of platinum and chromium by the garden snail (Helix aspersa) employing nano-secondary ion mass-spectrometry.

    Science.gov (United States)

    Eybe, Tanja; Audinot, Jean-Nicolas; Udelhoven, Thomas; Lentzen, Esther; El Adib, Brahime; Ziebel, Johanna; Hoffmann, Lucien; Bohn, Torsten

    2013-02-01

    Environmental heavy metal contamination is a case of concern for both animal and human health. Studying the fate of metals in plant or animal tissues may provide information on pollution. In the present study, we investigated the possibility to follow the biological fate of chromium and platinum uptake in common garden snails (Helix aspersa), typically accumulating high concentrations of metals from their environment. Chromium and platinum were administered orally to snails in 5 groups (n=25/group): control, food contaminated by ca. 2.5 μg g(-1) and 19 μg g(-1) chromium and 2.5 μg g(-1) and 25 μg g(-1) platinum, for 8 weeks. Following exposure, surviving snails were sacrificed, shell and remaining tissue investigated by ICP-MS, and shell, midgut gland and mantle by nano-secondary ion mass-spectrometry (Nano-SIMS). (12)C(14)N-normalized platinum and (40)Ca-normalized chromium measurements indicated highest enrichments in cellular vesicles of the midgut gland, and lower concentrations in mantle and shell, with significantly higher platinum and chromium concentrations in the 2 exposure groups vs. control (Psnails showing drastically elevated concentrations of metals in shell (up to 78 and 122 μg g(-1) dw platinum and chromium, respectively) and in other tissues (up to 200 and 1125 μg g(-1) dw platinum and chromium, respectively). Nano-SIMS allowed for semi-quantitative comparison of metal fate in snail tissues, making this an interesting technique for future studies in the area of environmental pollution. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. A higher chromium weld overlay alloy for waterwalls and superheaters

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Larry; Clark, Gregg [ThyssenKrupp VDM USA, Inc., Tipton, IN (United States)

    2009-08-15

    generally referred to as ''circumferential cracking'' in the industry. After 5 years of operation in multiple boilers, the high chromium Alloy 33 continues to perform very well with excellent resistance to both corrosion and cracking. In the convection pass of boilers, high temperature corrosion can severely limit the life of tubing, particularly if a coal ash corrosion (molten salt) mechanism is operating. Some recent investigations have identified carburization and sulfidation as serious problems for convection pass tubes. Corrosion problems in the convection pass area seem to be aggravated by low NOx firing; the completion of combustion further up in the boiler fundamentally changes the corrosive environment that superheater and reheater tubes face. Fortunately, the resistance to all of these forms of corrosion has a common thread: increasing the chromium content of a material increases resistance to carburization, sulfidation, and coal ash corrosion. Because of its high chromium level Alloy 33 has been gaining increasing interest for use on high temperature convection pass tubing. Alloy 33 has been seen to resist corrosion in oil-fired boilers, black liquor recovery boilers, and of course in coal-fired boilers; the previously mentioned corrosion mechanisms operate in these other boiler types as well. Alloy 33 has now been in commercial service for over 3 years and continues to gain positive experience in the field. (orig.)

  12. Study on Leaching of Hexavalent Chromium from Hardened Concretes Using Tank Leaching Test

    OpenAIRE

    Takahashi, Shigeru; Sakai, Etsuo; Sugiyama, Takafumi

    2007-01-01

    Tank leaching tests were carried out to investigate the behavior of leaching trace elements from monolith samples. This study consists of two series, and the trace element used was hexavalent chromium. In Series I, the influence of the leachant/surface area of the specimen (L/S ratio) on the leaching amount was investigated. The leaching amount was found to increase with the amount of worked water. This shows that any L/S ratio can be selected in the tank leaching test. In Series II, th...

  13. Investigation of in vivo potential of scorpion venom against skin tumorigenesis in mice via targeting markers associated with cancer development

    Directory of Open Access Journals (Sweden)

    Al Asmari AK

    2016-10-01

    Full Text Available Abdulrahman K Al Asmari, Abdul Quaiyoom Khan Research Centre, Prince Sultan Military Medical City, Riyadh, Saudi Arabia Abstract: Cancer is the leading cause of morbidity and mortality all over the world in spite of the advances made in its management. In this study, we investigated the in vivo antitumorigenic potential of the venom obtained from a medically important scorpion species Leiurus quinquestriatus on chemically induced skin cancer in mice. Animals were divided into five groups, with 13 animals in each group. All the treatments were given topically on the shaved dorsal surface of the skin. Animals in Group 1 received vehicle only (0.2 mL acetone. Moreover, 7,12-dimethylbenz[a]anthracene (DMBA, 400 nmol per mouse was applied to all the animals in the remaining four groups. After 1 week, different concentrations of venom (17.5 µg, 35 µg, and 52.5 µg per animal were applied to each animal in the Groups III–V. Thirty minutes after the application of venom, croton oil was applied on the same position where venom was administered to the animals of Groups III–V. Animals in Group II were treated as the positive control (without venom and received croton oil as in Groups III–V. The findings of this study revealed that venom extract of L. quinquestriatus inhibits DMBA + croton oil-induced mouse skin tumor incidence and tumor multiplicity. Venom treatment also decreased the expression of proinflammatory cytokines. Immunohistochemistry results showed a downregulation of the expression of molecular markers such as Ki-67, nuclear factor kappa-B, cyclooxygenase-2, B-cell lymphoma-2, and vascular endothelial growth factor, in venom-treated animals. Our findings suggest that the venom of L. quinquestriatus possesses in vivo anticancer potential and may be used in the development of anticancer molecules. Keywords: Leiurus quinquestriatus, skin cancer, apoptosis, immunosuppression

  14. Chromium(VI) release from leather and metals can be detected with a diphenylcarbazide spot test

    DEFF Research Database (Denmark)

    Bregnbak, David; Johansen, Jeanne D.; Jellesen, Morten Stendahl

    2015-01-01

    Along with chromium, nickel and cobalt are the clinically most important metal allergens. However, unlike for nickel and cobalt, there is no validated colorimetric spot test that detects chromium. Such a test could help both clinicians and their patients with chromium dermatitis to identify culprit...... exposures. To evaluate the use of diphenylcarbazide (DPC) as a spot test reagent for the identification of chromium(VI) release. A colorimetric chromium(VI) spot test based on DPC was prepared and used on different items from small market surveys. The DPC spot test was able to identify chromium(VI) release...

  15. Colloidal gold nanoparticle probe-based immunochromatographic assay for the rapid detection of chromium ions in water and serum samples

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xi; Xiang, Jun-Jian; Tang, Yong; Zhang, Xiao-Li; Fu, Qiang-Qiang; Zou, Jun-Hui; Lin, Yuehe

    2012-09-01

    An immunochromatographic assay (ICA) using gold nanoparticles coated with monoclonal antibody (McAb) for the detection of chromium ions (Cr) in water and serum samples was developed, optimized, and validated. Gold nanoparticles coated with affinity- purified monoclonal antibodies against isothiocyanobenzyl-EDTA (iEDTA)-chelated Cr3+ were used as the detecting reagent in this completive immunoassay-based one- step test strip. The ICA was investigated to measure chromium speciation in water samples. Chromium standard samples of 0-80 ng/mL in water were determined by the test strips. The results showed that the visual lowest detection limit (LDL) of the test strip was 50.0 ng/mL. A portable colorimetric lateral flow reader was used for the quantification of Cr. The results indicated that the linear range of the ICA with colorimetric detection was 5-80 ng/mL. The ICA was also validated for the detection of chromium ions in serum samples. The test trips showed high stability in that they could be stored at at 37 C for at least 12 weeks without significant loss of activity. The test strip also showed good selectivity for Cr detection with negligible interference from other heavy metals. Because of its low cost and short testing time (within 5 min), the test strip is especially suitable for on-site large- scale screening of Cr-polluted water samples, biomonitoring of Cr exposure, and many other field applications.

  16. Mechanical and tribological characterization of the Al 6061-T651 and the Al 6061-T651 with chromium phosphate coating

    International Nuclear Information System (INIS)

    Pena B, A.

    2002-01-01

    This work consist of two parts. The first one, related with theoretic concepts of tribology, condensed the friction and wear phenomena, considering aspects to bring something relevant into a process. In this conditions, to add lubricant cause a significant performance change during the phenomena mentioned above. The second part of this work, described experimental aspects as how we do a chromium phosphate coating in immersion cell, using 6061-T651 aluminum as substrate. In the process, we consider values of parameters in optimum conditions, obtained by commercial aluminum during previous investigations made in National Institute of Nuclear Research. Here, we characterized chromium phosphate coating and, 6061-T651 aluminum alloy using Sem and X-Ray Diffraction techniques. The measurement of some chromium phosphate characteristic as thickness, weight for area unit, density, roughness, microhardness, adhesion and corrosion resistant were made with appropriately equipment and, in accordance with international standards procedures. In tribological aspect, we determinate adhesive wear resistance and abrasive wear resistance for 6061-T651 aluminum alloy and chromium phosphate coating. Adhesive wear resistance was made for dry condition while abrasive wear resistance were made for dry and wet conditions. Tests are to guide by ASTM G99, G65 and G105 designations respectively. (Author)

  17. A Rare Terminal Dinitrogen Complex of Chromium

    Energy Technology Data Exchange (ETDEWEB)

    Mock, Michael T.; Chen, Shentan; Rousseau, Roger J.; O' Hagan, Molly J.; Dougherty, William G.; Kassel, W. S.; DuBois, Daniel L.; Bullock, R. Morris

    2011-10-12

    The reduction of dinitrogen to ammonia from N2 and H2 is currently carried out by the Haber-Bosch process, an energy intensive process that requires high pressures and high temperatures and accounts for the production of millions of tons of ammonia per year. The development of a catalytic, energy-efficient process for N2 reduction is of great interest and remains a formidable challenge. In this communication, we are reporting the preparation, characterization and computational electronic structure analysis of a rare 'Chatt-type' ((P-P)2M(N2)2, P-P = diphosphine ligand) complex of chromium, cis-[Cr(N2)2(PPh2NBn2)2] and its reactivity with CO. This complex is supported by the diphosphine ligand PPh2NBn2, containing non-coordinating pendant amine bases, to serve as proton relays. Future studies for this complex are aimed at answering fundamental questions regarding the role of proton relays in the second coordination sphere in their ability to facilitate proton movement from an external acid to metal-bound dinitrogen ligands in the challenging multi-proton/electron reduction of N2 to ammonia.

  18. Neutron Scattering Studies of Pure and Chromium - Vanadium Sesquioxide

    Science.gov (United States)

    Yethiraj, Mohana

    1985-12-01

    The metal insulator transitions in pure and chromium -doped vanadium sesquioxide (V(,2)O(,3)) were investigated using elastic and inelastic neutron scattering techniques. These samples undergo a number of transitions as a function of temperature and doping. At the highest temperature, all specimens are in a metallic (M') phase. As the temperature is lowered, samples with less than 0.5% Cr transform to a second metallic (M) state. For those samples with Cr content between 0.5% and 1.8%, the system transforms to an insulating (I') phase prior to the transition to the M phase. For samples with >1.8% Cr, the M phase is entirely bypassed. At temperatures below (TURN)160K, all samples transform to an antiferromagnetic insulating (AFI) phase. The transition to the AFI state is accompanied by a structural distortion as well. The aim of this study was to add to our understanding of the driving mechanism(s) effecting the various metal-insulator transformations and in particular, the low temperature magnetic transition.

  19. Hexavalent chromium removal by viable, granular anaerobic biomass.

    Science.gov (United States)

    Massara, Hafez; Mulligan, Catherine N; Hadjinicolaou, John

    2008-12-01

    Hexavalent chromium in industrial wastewater is a major concern due to its extreme toxicity. This study investigates the removal of Cr(VI) using viable anaerobic granular biomass as a biosorbent. The effect of Cr(VI) concentration on biogas content and COD removal using batch studies indicated that the phase II (methanogenic-rich) culture was more sensitive than the phase I (acidogenic-rich) culture. Toxicity indices for both cultures using COD removal were developed based on linear-log interpolation. The median inhibition Cr(VI) concentration (IC(50)), for phase II cultures was found to be 263mg/L, while that for phase I cultures was 309mg/L. A sorption study was conducted on viable and non-viable (dried) phase I-rich biomass: both followed the Langmuir model. In addition, the biosorption capacity for metabolically inhibited biomass was 25% less indicating some level of cellular uptake associated with Cr(VI) removal. This study demonstrated the potential for a two-phase anaerobic treatment system for a Cr(VI)-contaminated effluent.

  20. Biosorption of hexavalent chromium from aqueous medium with Opuntia biomass.

    Science.gov (United States)

    Fernández-López, José A; Angosto, José M; Avilés, María D

    2014-01-01

    The biosorption of hexavalent chromium from aqueous solutions by Opuntia cladodes and ectodermis from cactus fruits was investigated. Both types of biomass are considered low-cost, natural, and ecofriendly biosorbents. Batch experiments were carried out to determine Cr(VI) biosorption capacity and the efficiency of the biosorption process under different pH, initial Cr(VI) concentration, and sorbent dosage. The biosorption of Cr(VI) by Opuntia biomass was highly pH dependent, favoring higher metal uptake at low pH. The higher biosorption capacity was exhibited at pH 2. The optimal conditions were obtained at a sorbent dosage of 1 g L(-1) and initial metal concentration of 10 mg L(-1). Biosorption kinetic data were properly fitted with the pseudo-second-order kinetic model. The rate constant, the initial biosorption rate, and the equilibrium biosorption capacity were determined. The experimental equilibrium data obtained were analyzed using two-parameter isotherm models (Langmuir, Freundlich, and Temkin). The Langmuir maximum monolayer biosorption capacity (q max) was 18.5 mg g(-1) for cladodes and 16.4 mg g(-1) for ectodermis. The results suggest that Opuntia biomass could be considered a promising low-cost biosorbent for the ecofriendly removal of Cr(VI) from aqueous systems.