WorldWideScience

Sample records for chromium 55

  1. Chromium

    Science.gov (United States)

    ... health risks of too much chromium? Chromium and medication interactions Supplemental sources of chromium Chromium and Healthful Diets References Disclaimer What foods provide chromium? Chromium is widely distributed in the ...

  2. Heterogeneous chromium catalysts

    OpenAIRE

    2005-01-01

    The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based silica-containing support, (c) activating the chromium-based silica-containing support, (d) chemically reducing the activated chromium-based silica-containing support to produce a precursor catalyst, (e) r...

  3. Enhancement of the acute phase response to lipopolysaccharide (LPS) challenge in steers supplemented with chromium

    Science.gov (United States)

    The study examined the effect of chromium supplementation on the response of steers to an LPS challenge. Twenty steers received a premix that added 0 (control) or 0.2 mg/kg of chromium (KemTRACE®brandChromiumProprionate 0.04%, Kemin Industries) to the total diet on a dry matter basis for 55 d. Steer...

  4. Hexavalent Chromium Workshop

    Science.gov (United States)

    EPA is developing an updated IRIS assessment of hexavalent chromium. This assessment will evaluate the potential health effects of hexavalent chromium from oral and inhalation exposures. An important component of determining the cancer causing potential of ingested hexavalent chr...

  5. Chromium and Genomic Stability

    OpenAIRE

    Wise, Sandra S.; Wise, John Pierce

    2011-01-01

    Many metals serve as micronutrients which protect against genomic instability. Chromium is most abundant in its trivalent and hexavalent forms. Trivalent chromium has historically been considered an essential element, though recent data indicate that while it can have pharmacological effects and value, it is not essential. There are no data indicating that trivalent chromium promotes genomic stability and, instead may promote genomic instability. Hexavalent chromium is widely accepted as high...

  6. CLUB 55

    Directory of Open Access Journals (Sweden)

    Ramón Rojano

    2000-01-01

    Full Text Available Este artículo presenta una reconceptualización del concepto de envejecimento. Se plantea la necesidad de revisar las etapas del desarrollo psicológico descritas por Erikson. Los recientes cambios demográficos y la prolongación de la expectativa de vida justifican el replanteamiento conceptual. Actualmente la tercera edad no es la última edad. Características que se le atribuían a este período de la vida ahora corresponden a la cuarta edad. El Departamento de Servicios Humanos de Hartford ha creado el Club 55, un proyecto basado en este nuevo paradigma.

  7. Hidroroute 55

    Science.gov (United States)

    Mas, M.; Eixarch, E.; Ortonobes, C.

    2012-04-01

    "HIDROROUTE 55" Saving water is a recurrent topic for students in Spain because the Mediterranean zone suffers periodically severe droughts. Any student knows it and is able to repeat some basic advices like "take showers instead of baths, or "close the tap when brushing your teeth..." But maybe this is a quite superficial awareness about shortage and saving water. Where does the home flowing water come from? How can we be sure that this water is clean and safe to drink? And, tomorrow or next week, will be there water in our tap? Perhaps working in these questions is a good way to understand how difficult is to get water to our homes. In order to deepen in the question we are preparing a teaching unit titled "Hydro route 55: from the Earth to la Maurina trough the water" on 1rst ESO level students (12 years old) of the secondary public school "Institut les Aymerigues" in Terrassa (Barcelona). Students' tasks will be to search information about the way water gets to their homes, including water cycle, treatment and saving water... This unit belongs to an integrated project with all areas involved (history, mathematics, technology, languages and music) that aims to approach students to different aspects of their zone in Terrassa (La Maurina) and it will be implemented at the end of the second term, just some weeks before the Vienna's meeting. School and teaching team: Institut les Aymerigues is a new school that this year has only 1rst ESO students (12 years old). Teaching staff is engaged in developing an integrated and based on competences curriculum. In this context we integrate English and Science content in a unified teaching schedule of six hours per week for the students. One English teacher and two Science teachers are involved in it. In addition we have three student teachers from "Master of Secondary Teachers Training" that are in charge of preparing the Hydroroute 55 activities with the titular teachers. We illustrate students' tasks such as the

  8. Oxidation of chromium telluride

    International Nuclear Information System (INIS)

    The authors study the interaction between chromium telluride and oxygen at elevated temperatures in view of its application in semiconductor technology. Thermodynamic analysis of the oxidation process and experimental data showed that the alloys of chromium telluride suffer oxidation in the presence of even traces of oxygen in a gaseous medium. Chromium telluride oxidation is a complex process that gives rise to various oxides and is accompanied by partial sublimation

  9. Oxidation of chromium telluride

    Energy Technology Data Exchange (ETDEWEB)

    Pakhomovskaya, N.S.; Iorga, E.V.; Sheveleva, T.F.; Solov' eva, A.E.

    1986-03-01

    The authors study the interaction between chromium telluride and oxygen at elevated temperatures in view of its application in semiconductor technology. Thermodynamic analysis of the oxidation process and experimental data showed that the alloys of chromium telluride suffer oxidation in the presence of even traces of oxygen in a gaseous medium. Chromium telluride oxidation is a complex process that gives rise to various oxides and is accompanied by partial sublimation.

  10. 10 CFR 55.55 - Expiration.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Expiration. 55.55 Section 55.55 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) OPERATORS' LICENSES Licenses § 55.55 Expiration. (a) Each operator license and senior... existing license on Form NRC-398 at least 30 days before the expiration of the existing license, it...

  11. Specific features of the electrocrystallization of chromium together with molybdenum

    International Nuclear Information System (INIS)

    A study was made on molybdenum effect on surface structure and some physicomechanical properties of electrolytic chromium during Cr-Mo electrodeposition from CrO3 solutions with additions of SO42- and SiFe62- anions. Cr-Mo deposition was conducted at 55 deg C and 0.5 A/cm2 current density which corresponds to conditions of hard chromizing. It is shown that the change hardness, hydridation and internal stresses of chromium coatings during their alloying with molybdenum is conditioned by structure change. Mo introduction into chromium is not manifested clearly in these characteristics. The change of chromium structure during deposition with molybdenum is probably related both with change of anion relation in cathode film (decrease of catalytic anion content in it) and peculiarities of chromium electrocrystallization. This requires special study with application of methods for investigation into fine and surface structure

  12. Hair chromium concentration and chromium excretion in tannery workers.

    OpenAIRE

    Saner, G; Yüzbasiyan, V; Cigdem, S

    1984-01-01

    Hair and urine samples were collected from 34 male tannery workers and from 12 normal adults. Eighteen of the workers dealt directly with chromium and the remaining 16 (controls) worked in the offices and kitchen of the same factory. All were found to be clinically healthy. Chromium was determined by flameless atomic absorption spectroscopy. When compared with normal adult values, urinary chromium concentration, Cr/Creatinine ratio, daily chromium excretion, and hair chromium, concentrations ...

  13. High-Purity Chromium Targets

    OpenAIRE

    Rudoy, A.; Milman, Yu.; Korzhova, N.

    1995-01-01

    A procedure for producing large-scale chromium ingots by means of induction-arc melting was developed. From the high-purity, low-alloyed chromium ingots obtained, chromium targets were produced by of thermoplastic treatment techniques. The method of electron-beam evaporation of high-purity chromium was also used for production of targets.

  14. Microstructural characterisation of chromium slags

    OpenAIRE

    Burja, J.; F. Tehovnik; Vode, F.; Arh, B.

    2015-01-01

    In this chromium slags that form during melting of chromium alloyed steels are examined. During melting and oxidation of these steel grades a considerable amount of chromium is lost, and gained back with slag reduction. Laboratory experiments were performed to study the mechanism of chromium oxide reduction by silicon. Slags chemistry and phase composition have a strong effect on the steelmaking process. Phase analysis revealed two types of chromium oxides, calcium chromites and chromite spin...

  15. Neutron scattering and models: Chromium

    International Nuclear Information System (INIS)

    Differential neutron elastic-scattering cross sections of elemental chromium are measured from 4.5 ∼ 10 MeV in steps of ∼ 0.5 MeV and at ≥ 40 scattering angles distributed between ∼ 17 degree--160 degree. Concurrently differential cross sections for the inelastic neutron excitation of the yrast 2+ (1.434 MeV) level in d52Cr are determined. In addition, broad inelastically-scattered neutron groups are observed corresponding to composite excitation of levels up to ∼ 5.5 MeV in the various chromium isotopes. These experimental results are combined with low-energy values previously reported from this laboratory, with recent ∼ 8 → 15 MeV data measured at the Physikalisch-Technische Bundesanstalt and with a 21.6 MeV result from the literature to form an extensive neutron-scattering data base which is interpreted in the context of spherical-optical and coupled-channels (rotational and vibrational) models. These models reasonably describe the observables but indicate rather large energy-dependent parameter trends at low energies similar to those previously reported near the peak of the So strength function in studies at this laboratory. The physical implications of the measurements and models are discussed including deformation, coupling, dispersive and asymmetry effects

  16. Substoichiometric extraction of chromium

    International Nuclear Information System (INIS)

    Substoichiometric extraction of chromium with tetraphenylarsonium chloride (TPACl), tri-n-octylamine (TNOA), diethylammonium diethyldithiocarbamate (DDDC) and ammonium pyrrolidinedithiocarbamate (APDC) was examined in detail. Chromium can be extracted substoichiometrically in a pH range, which is 1.1-2.6 for the TPACl compound, 0.6-2.3 for the TNOA compound, 5.1-6.4 for the DDDC chelate and 3.9-4.9 for the APDC chelate. Chromium in high-purity calcium carbonate, Orchard Leaves (NBS SRM-1571) and Brewers Yeast (NBS SRM-1569) was determined by neutron activation analysis combined with substoichiometric extraction by DDDC and APDC. The values of 2.0+-0.02 ppm and 2.6+-0.2 ppm were obtained for Brewers Yeast and Orchard Leaves, respectively. These values were in good agreement with those reported by NBS. The reaction mechanism and the reaction ratio between hexavalent chromium and dithiocarbamate are also discussed. (author)

  17. Chromium in diet

    Science.gov (United States)

    ... Chromium deficiency may be seen as impaired glucose tolerance. It occurs in older people with type 2 ... PhD, and the A.D.A.M. Editorial team. Related MedlinePlus Health Topics Minerals Browse the Encyclopedia ...

  18. The carcinogenicity of chromium

    OpenAIRE

    Norseth, Tor

    1981-01-01

    The carcinogenicity of chromium compounds is reviewed with specific attention to the gaps in knowledge for risk estimation and research needs. The most important problems at present are whether trivalent chromium compounds cause cancer, and whether there is a difference in cancer causing effects between the soluble and the slightly soluble hexavalent compounds in the practical exposure situation. Dose estimates for risk estimation based on epidemiological investigations are also lacking. Pres...

  19. Chromium supplementation enhances the acute phase response of steers to a lipopolysaccharide (LPS) challenge

    Science.gov (United States)

    The study examined the effect of chromium supplementation on the response of steers to an LPS challenge. Twenty crossbred steers (235±4 kg BW) received 0 ppb (Control; C) or 200 ppb chromium propionate (CHR) for 55 days. Steers were fitted with jugular catheters and rectal temperature (RT) recording...

  20. Obtaining decorative chromium plating from trivalent chromium solutions

    OpenAIRE

    Óscar Javier Suárez García

    2010-01-01

    The present work was aimed at a qualitative evaluation, in the laboratory, of different alternatives for assembling and operating a trivalent chromium bath for decorative chromium plating. Different chromium concentration solutions and different complexing agents were used. The initial result of this analysis was that chloride, formate and acetate solutions produced the best results. Solution preparation conditions were evaluated: temperature, chromium III complex formation time and also ...

  1. Design and performance of chromium mist generator

    Directory of Open Access Journals (Sweden)

    Tirgar Aram

    2006-01-01

    Full Text Available Chromium mist generator is an essential tool for conducting researches and making science-based recommendations to evaluate air pollution and its control systems. The purpose of this research was to design and construct a homogenous chromium mist generator and the study of some effective factors including sampling height and distances between samplers in side-by-side sampling on chromium mist sampling method. A mist generator was constructed, using a chromium electroplating bath in pilot scale. Concentration of CrO3 and sulfuric acid in plating solution was 125 g L-1 and 1.25 g L-1, respectively. In order to create permanent air sampling locations, a Plexiglas cylindrical chamber (75 cm height, 55 cm i.d was installed the bath overhead. Sixty holes were produced on the chamber in 3 rows (each 20. The distance between rows and holes was 15 and 7.5 cm, respectively. Homogeneity and effective factors were studied via side-by-side air sampling method. So, 48 clusters of samples were collected on polyvinyl chloride (PVC filters housed in sampling cassettes. Cassettes were located in 35, 50, and 65 cm above the solution surface with less than 7.5 and/or 7.5-15 cm distance between heads. All samples were analyzed according to the NIOSH method 7600. According to the ANOVA test, no significant differences were observed between different sampling locations in side-by-side sampling (P=0.82 and between sampling heights and different samplers distances (P=0.86 and 0.86, respectively. However, there were notable differences between means of coefficient of variations (CV in various heights and distances. It is concluded that the most chromium mist homogeneity could be obtained at height 50 cm from the bath solution surface and samplers distance of < 7.5 cm.

  2. The analytical biochemistry of chromium.

    OpenAIRE

    Katz, S A

    1991-01-01

    The essentiality and carcinogenicity of chromium depend on its chemical form. Oxidation state and solubility are particularly important in determining the biological effects of chromium compounds. For this reason, total chromium measurements are of little value in assessing its nutritional benefits or its toxicological hazards. Aqueous sodium carbonate-sodium hydroxide solutions have been successfully used for extracting hexavalent chromium from a variety of environmental and biological matri...

  3. Chromium in potatoes

    International Nuclear Information System (INIS)

    Chromium concentration in potatoes was determined, and tubes were labeled either intrinsically or extrinsically with radioactive chromate (51Cr). A labeled chromium complex was isolated from preparations of raw, baked, or fried potatoes and chromatographed on gel permeation media. Potato pulp and peel contained 1.63 and 2.70 μg of Cr/g tissue, respectively. There was no correlation between the two, nor did they respond similarly to changes of variety or locations. No significant differences were apparent in relative migration of the isolated complexes except between raw and cooked extrinsically labeled preparations

  4. The chromium accumulation and its physiological effects in juvenile rockfish, Sebastes schlegelii, exposed to different levels of dietary chromium (Cr(6+)) concentrations.

    Science.gov (United States)

    Kim, Jun-Hwan; Kang, Ju-Chan

    2016-01-01

    Juvenile rockfish (mean length 13.7±1.7 cm, and mean weight 55.6±4.8 g) were exposed for 4 weeks with the different levels of dietary chromium (Cr(6+)) at 0, 30, 60, 120 and 240 mg/kg. The profile of chromium in the tissues of rockfish is dependent on the exposure periods and chromium concentration. After 4 weeks, the order of chromium accumulation in tissues was liver>kidney>spleen>intestine>gill>muscle. The dietary chromium exposure decreased the growth rate and hepatosomatic index of rockfish. The major hematological findings were significant decrease in the red blood cell (RBC) count, hematocrit (Ht) value, and hemoglobin (Hb) concentration exposed to ≥120 mg/kg chromium concentrations. The dietary chromium exposure (≥120 mg/kg) led to notable increase in glucose, cholesterol, glutamic oxalate transaminase (GOT), and glutamic pyruvate transaminase (GPT) in plasma, whereas there was no considerable change in calcium, magnesium, total protein, and alkaline phosphatase (ALP). The results indicated that the dietary chromium exposure to rockfish can induce significant chromium accumulation in the specific tissues, inhibition of growth, and hematological alterations. PMID:26705966

  5. 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...

  6. Studies of chromium gettering

    International Nuclear Information System (INIS)

    Preliminary results have shown that hydrogen pumping by chromium is a surface effect. Unlike with titanium, the getter material used in many present day tokamaks, there is no significant diffusion into the bulk. Additional experiments have been carried out to measure the basic characteristics of chromium films for gases of interest in tokamak research. These gases include deuterium, oxygen and nitrogen. A vacuum system is described which allowed precise control of the test gas, a constant wall temperature and determination of the projected getter surface area. A quadrupole mass spectrometer, rather than simply a total pressure gauge, was utilized to measure the partial pressure of the test gas as well as the residual gas composition in the system. A quartz crystal monitor was used to measure film thickness. Pumping speeds and sticking coefficients are given as a function of surface coverage for each test gas. A comparison will be made with titanium films deposited in the same vacuum system and under similar conditions

  7. Catalytic Spectrophotometric Determination of Chromium

    OpenAIRE

    STOYANOVA, Angelina Miltcheva

    2005-01-01

    The catalytic effect of chromium(III) and chromium(VI) on the oxidation of sulfanilic acid by hydrogen peroxide was studied. The reaction was followed spectrophotometrically by measuring the absorbance of the reaction product at 360 nm. Under the optimum conditions 2 calibration graphs (for chromium(III) up to 100 ng mL-1, and for chromium(VI) up to 200 ng mL-1) were obtained, using the ``fixed time'' method with detection limits of 4.9 ng mL-1 and 3.8 ng mL-1, respectively...

  8. Conversion of Chromium(III) Propionate to Chromate/dichromate(VI) by the Advanced Oxidation Process. Pretreatment of a Biomimetic Complex for Metal Analysis

    OpenAIRE

    Lynn Rodman, D.; Carrington, Nathan A.; Xue, Zi-Ling

    2006-01-01

    The use of H2O2 and UV irradiation to remove organic ligands in a chromium(III) complex for the subsequent chromium analysis is reported. The Advanced Oxidation Process (AOP) using a 5.5-W UV lamp, H2O2 and Fe2+/Fe3+ as catalyst (photo Fenton process) was found to give complete and quantitative Cr(III) → Cr(VI) conversion and removal of ligands in chromium(III) propionate [Cr3O(O2CCH2CH3)6(H2O)3]NO3, a biomimetic chromium species, as subsequent chromium analyses by the 1,5-diphenylcarbazide m...

  9. CHROMIUM, METABOLIC SYNDROME AND DIABESITY

    Science.gov (United States)

    Suboptimal intakes of the essential nutrient, chromium, are characterized by elevated blood glucose, insulin resistance, obesity, hypertriglyceridemia, and low HDL. These are also signs and symptoms of the metabolic syndrome. Improvements due to increased intake of chromium are related to the degr...

  10. Anti-diabetic potential of chromium histidinate in diabetic retinopathy rats

    OpenAIRE

    Ulas, Mustafa; Orhan, Cemal; Tuzcu, Mehmet; Ozercan, Ibrahim Hanifi; Sahin, Nurhan; Gencoglu, Hasan; Komorowski, James R; Sahin, Kazim

    2015-01-01

    Background Chromium (Cr) is commonly used as a complementary medicine for diabetes mellitus. Several studies suggest that Cr intakes may improve glucose metabolism and decrease oxidative stress. Therefore, we aimed to assess the effects of chromium histidinate (CrHis) supplementation using a range of reliable biomarkers of oxidative damage and histopathological changes in rats with diabetic retinopathy. Methods Diabetes was induced with streptozotocin [(STZ), 55 mg/kg] by intraperitoneal inje...

  11. Groundwater contaminant by hexavalent chromium

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, C. [Univ. of Texas, Austin, TX (United States)

    1995-11-01

    Oxidation of trivalent chromium to hexavalent chromium has been investigated as a function of total manganese in soils as well as various incubation conditions. Chromium and manganese contents were analyzed by atomic absorption (graphite furnace and flame emission respectively) following acid digestion. Total hexavalent chromium generation capacity was determined by addition of 0.001 M CrCL3, incubation, and analysis by s-diphenyl carbazide. Samples were then leached with CaSO{sub 4} and MgSO{sub 4} and incubated in various environments (oven, freeze-drier, field moist, ultrafreeze) to test for geogenic generation of Cr(IV). The degree of geogenic generation of hexavalent chromium was compared with total Mn and Cr content as well as hexavalent generational capacity.

  12. 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...

  13. Fate and transport of chromium through soil

    International Nuclear Information System (INIS)

    Chromium chemistry relevant to the problem facing state of New Jersey (Usa) was examined. Transport of chromium through soil depends on its chemical forms. Transformation of chromium within bulk of soil depends on soil constituents, soil condition, such as pH, Eh and organic compounds applied onto soil or present in soil. Total chromium in soil can be determined. Speciation of chromium based on ionization, hydrolysis, complex formation, redox reactions and adsorption is predicted using MINIQ program

  14. Release of Chromium from Orthopaedic Arthroplasties

    OpenAIRE

    Afolaranmi, G.A.; Tettey, J; Meek, R.M.D; Grant, M.H

    2008-01-01

    Many orthopaedic implants are composed of alloys containing chromium. Of particular relevance is the increasing number of Cobalt Chromium bearing arthroplasies being inserted into young patients with osteoarthritis. Such implants will release chromium ions. These patients will be exposed to the released chromium for over 50 years in some cases. The subsequent chromium ion metabolism and redistribution in fluid and tissue compartments is complex. In addition, the potential biological effects o...

  15. 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...... is incorporated into carbonates. Hence, ancient carbonates can potentially record the Cr isotopic composition (δ53Cr ‰) of seawater in the geological past. Reliable application and interpretation of this proxy requires a detailed knowledge about processes that fractionate Cr on the Earth’s surface......, and the quantification the Cr isotope composition of major Cr fluxes into and out of ocean. This thesis adds to the current knowledge of the Cr isotope system and is divided into two studies. The focus of the first study was to determine what processes control the Cr isotopic compositionof river...

  16. Chromium reduction in Pseudomonas putida.

    OpenAIRE

    Ishibashi, Y.; Cervantes, C; Silver, S

    1990-01-01

    Reduction of hexavalent chromium (chromate) to less-toxic trivalent chromium was studied by using cell suspensions and cell-free supernatant fluids from Pseudomonas putida PRS2000. Chromate reductase activity was associated with soluble protein and not with the membrane fraction. The crude enzyme activity was heat labile and showed a Km of 40 microM CrO4(2-). Neither sulfate nor nitrate affected chromate reduction either in vitro or with intact cells.

  17. Chromium reduction in Pseudomonas putida.

    Science.gov (United States)

    Ishibashi, Y; Cervantes, C; Silver, S

    1990-01-01

    Reduction of hexavalent chromium (chromate) to less-toxic trivalent chromium was studied by using cell suspensions and cell-free supernatant fluids from Pseudomonas putida PRS2000. Chromate reductase activity was associated with soluble protein and not with the membrane fraction. The crude enzyme activity was heat labile and showed a Km of 40 microM CrO4(2-). Neither sulfate nor nitrate affected chromate reduction either in vitro or with intact cells. PMID:2389940

  18. REMOVAL OF LEAD AND CHROMIUM FROM AQUEOUS SOLUTION BY BACILLUS CIRCULANS BIOFILM

    Directory of Open Access Journals (Sweden)

    A. Khanafari, S. Eshghdoost, A. Mashinchian

    2008-07-01

    Full Text Available The different methods are used for the removal of heavy metals as important contaminants in water and wastewater. Biosorption is an alternative to traditional physicochemical in removing toxic metals from wastewaters and groundwater resources. In this study biosorption of lead and chromium ions from solution was studied using Bacillus circulans isolated from Anzali wetland in batch and biofilter modes and optimum conditions were determined. The experimental results showed 900-950 mg/L and 1050-1100 mg/L, for minimum bactericidal concentration and minimum inhibitory concenteration for lead and chromium, respectively. Results of metal concentration in solution containing 500 mg/L in batch culture showed a reduction about 65% and 48% in five and four days for lead and chromium, respectively. The highest value of lead and chromium uptake in solution with 500 mg/L was 78% and 40% in biofilter mode, respectively. The biosorption of lead and chromium were increased up to pH=5.5, 6, 5.5 and 7, respectively. In the other hand, maximum sorption occurred at neutral pH. There was a significant decreasing of biosorption levels by lowering pH fewer than 3. Accumulation of lead and chromium was determined by scanning electron microscopy analysis of the biofilm exposed to 500 mg/L metal concentration. Based on this analysis, the highest metal concentrations were observed in regions with including bacteria.

  19. New alloys to conserve critical elements. [replacing chromium in steels

    Science.gov (United States)

    Stephens, J. R.

    1978-01-01

    Previous studies and surveys on availability of domestic reserves have shown that chromium is a most critical element within the U.S. metal industry. More precisely, the bulk of chromium is consumed in the production of stainless steels, specifically Type 304 stainless steel (304SS) which contains 18% Cr. The present paper deals with means of reducing chromium in commercial stainless steels by substituting more abundant or less expensive elements with the intent of maintaining the properties of 304SS. The discussion focuses on some of the oxidation and corrosion properties of new substitute stainless steels with only 12% Cr, which represents a potential saving of 33% of the chromium consumed in the production of 304SS. The alloying elements substituted for Cr in 304SS are selected according to their potential for protective oxide formation during high-temperature oxidation; these are Al, Si, Ti, Y, and misch metal which is 99.7% rare-earth metals containing 50 to 55% cerium. Other alloying elements to impart corrosion resistance are Mn, Mo, and V.

  20. Development of a hexavalent chromium ISFET sensor with a polymeric membrane including tributylphosphate

    International Nuclear Information System (INIS)

    This paper presents a first report on chromium ISFET (ion-sensitive field effect transistor) based on a polymeric membrane (siloprene) including an ionophore (tributylphosphate) sensitive for hexavalent chromium. The sensor sensitivity as a function of the pH was studied; its value is minimum in a pH interval from 5.5 to 7.5. The sensitivity for hexavalent chromium was found to be 15 mV/loga Cr6+ in the range of 10-4 to 10-2 M. The detection limit was found to be 10-5 M. The studied interfering ions are Pb(II) and Cd(II) that do not represent a great perturbation upon the response for hexavalent chromium

  1. Hydrogen permeation through chromium

    International Nuclear Information System (INIS)

    Steady state and non-steady state measurements of hydrogen permeation through metallic chromium are reported. The experiments have been conducted by use of hydrogen and deuterium within a pressure range of 10-8 - 1 bar and temperatures between 600 - 8000C. Numerical values for the physical quantities permeability, diffusion constant and solubility could be derived. At an upstream pressure above around 10-3 bar classical Sieverts-low was found (permeation rate proportional √p) with activation energies Qsub(perm) = 65 kJoule/mole, Qsub(Diff) = 4-8 kJoule/mole, Qsub(Sol) = 57-61 kJoule/mole for the respective processes involved. The isotopic effect between H and D of the permeabilities could be represented by a factor of 1,5 independence on temperature. All non steady-state measurements could be approximated reasonably well by classical diffusion kinetics. Below up-stream pressures of approx.= 10-7 bar the kinetics was no longer diffusion controlled, the dependence on up-stream pressure changed from √p -> p, the activation energy for permetation increased to 127 kJoule/mole and the isotopic factor resulted in about 2-3. (orig.)

  2. Phase equilibria in the uranium-chromium-carbon system

    International Nuclear Information System (INIS)

    The alloys for this study (40 different compositions) were prepared by melting a charge comprising appropriate amounts of the various components and a 'master' alloy under an argon atmosphere on a water-cooled copper tray in an arc furnace equipped with a tungsten electrode. The starting components were uranium of 99.7% purity, graphite with an 0.004% ash content and electrolytically prepared chromium. The alloys were analysed by X-ray spectroscopy, X-ray diffraction analysis and microstructural methods, and a selective chemical analysis was made. As a result of these studies, a new compound of composition 45 at.%Cr - 10 at.%U - 45 at.%C was found; it was subjected to X-ray diffraction analysis. The composition of the compound x(UCr2C3) was refined. The crystallization characteristics of the alloys were established over the entire composition range, a diagram of the non- and monovariant equilibria was drawn and the section for the sub-solidus temperature was constructed over the entire range of concentrations. The isothermal section at 1500-16000C was constructed for the UC2-UC-UCrC2 region; this is characterized by a broad region consisting of a homogeneous solid solution of chromium in the high-temperature (UC-β-UC2) solid solution, which the chromium stabilizes down to a lower temperature. The observed increase of the carbon content in the solid solution with increase in the content of iron can apparently explain the improvement of chromium-modified monocarbide nuclear fuel reported in the literature. The carbon content in uranium-based monocarbide fuel can be increased to approximately 55 at.% by the addition of approximately 7 at.% chromium without change in the crystal structure. The parameters of the tetragonal (UC-β-UC2) lattice were determined to be a=5.041 A and c=5.128 A

  3. 5.5 Summary

    Science.gov (United States)

    Almén, A.; Valentin, J.

    This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Section '5.5 Summary' of the Chapter '5 Medical Radiological Protection'.

  4. Trivalent chromium sorption on alginate beads

    OpenAIRE

    Araújo, M. Manuela; Teixeira, J.A.

    1997-01-01

    The applicability of trivalent chromium removal from aqueous solutions using calcium alginate beads was studied. The equilibrium isotherms were plotted at two temperatures. The relationship between the chromium sorbed and the calcium released was determined as well as the effect of alginate amount and initial pH on the equilibrium results. Chromium sorption kinetics were evaluated as a function of chromium initial concentration and temperature. Transport properties of trival...

  5. 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...

  6. EPR study of charge compensation of chromium centers in the strontium titanate crystal

    Czech Academy of Sciences Publication Activity Database

    Badalyan, A. G.; Azamat, Dmitry; Babunts, R.A.; Neverova, E.V.; Dejneka, Alexandr; Trepakov, Vladimír; Jastrabík, Lubomír

    2013-01-01

    Roč. 55, č. 7 (2013), 1454-1458. ISSN 1063-7834 R&D Projects: GA ČR GAP108/12/1941 Institutional support: RVO:68378271 Keywords : EPR spectroscopy * SrTiO3:Cr crystal * chromium centers Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.782, year: 2013

  7. Chromium Salen Mediated Alkene Epoxidation

    DEFF Research Database (Denmark)

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

    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......-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...

  8. Chromium content of selected Greek foods.

    Science.gov (United States)

    Bratakos, Michael S; Lazos, Evangelos S; Bratakos, Sotirios M

    2002-05-01

    The total chromium content of a wide variety of Greek foods was determined by graphite furnace atomic absorption spectroscopy (GFAAS). Meat, fish and seafood, cereals and pulses were rich sources of chromium (>0.100 microg/g). Fruits, milk, oils and fats and sugar were poor sources. Differences in chromium content were found between different food classes from Greece and those from some other countries. Based on available food consumption data and chromium levels in this study, it was estimated that the chromium intake of Greeks is 143 microg/day, with vegetables, cereals and meat being the main contributors. PMID:12083715

  9. Determination of chromium combined with DNA, RNA and protein in chromium-rich brewer's yeast

    International Nuclear Information System (INIS)

    The contents of chromium in the DNA, RNA and protein fractions separated from chromium-rich and normal brewer's yeast were determined with the neutron activation analysis in order to study the combination of Cr with DNA, RNA and protein in chromium-rich brewer's yeast. The results showed that the extracting rats and concentrations of DNA, RNA and protein had no significant difference in two types of yeast, but the chromium contents of DNA, RNA and protein in the chromium-rich yeast were significantly higher than those in the normal. In addition, the content of chromium in DNA was much higher than that in RNA and protein, which indicated that the inorganic chromium compounds entered into the yeast cell, during the yeast cultivation in the culture medium containing chromium were converted into organic chromium compounds combined with DNA, RNA and protein

  10. Chromium(VI) reduction by ascorbate: role of reactive intermediates in DNA damage in vitro.

    OpenAIRE

    Stearns, D M; Courtney, K D; Giangrande, P H; Phieffer, L S; Wetterhahn, K E

    1994-01-01

    Reaction of chromium(VI) with one equivalent of ascorbate was studied by electron paramagnetic resonance spectroscopy in the presence of 0.10 M 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) at room temperature in 0.10 M (N-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid]) (HEPES) and 0.05 M tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) buffers (pH 7.0 room temperature). Chromium(V), ascorbyl radical, and carbon-based DMPO-radical adducts were observed. A higher level of Cr(V) was ob...

  11. Tissues and urinary chromium concentrations in rats fed high-chromium diets

    International Nuclear Information System (INIS)

    Complete text of publication follows. Chromium is an essential trace elements and enhances the function of insulin as a form of chromodulin. In the subjects with a certain type of diabetics, 200 to 1,000 μg/d of chromium is administered to reduced the symptoms of diabetics. However, although there are not any health-promotive effects of chromium-administration in healthy subjects, various types of chromium supplements are commercially available in many countries; the adverse effects caused by an excessive chromium intake are feared. In the present study, to clarify the tolerable upper limit of chromium, tissue and urinary chromium concentrations, liver function and iron status were examined in rats fed high-chromium diets. Thirty-six male 4-weeks Wistar rats were divided into six groups and fed casein-based diets containing 1, 10 or 100 μg/g of chromium as chromium chloride (CrCl3) or chromium picolinate (CrPic) for 4 weeks. After the feeding, chromium concentrations in liver, kidney, small intestine and tibia were determined by inductively coupled plasma-mass spectrometry. In addition, urine samples were collected on 3rd to 4th week and their chromium concentrations were also determined. Chromium concentrations in liver, kidney, small intestine and tibia were elevated with increase of dietary chromium concentration. Urinary chromium excretion was also elevated with the increase of dietary chromium and the rate of urinary chromium excretion was less than 2% to dietary chromium intake in all the experimental groups. In the administration of 100 μg/g of chromium, rats given CrCl3 showed significantly higher tibia chromium concentration and lower urinary chromium excretion than those given CrPic. There were not any differences in iron status among the experimental groups. Activities of serum aspartate aminotransferase and alanine aminotransferase in rats fed diet containing 100 μg/g of chromium as CrPic were significantly higher than those in rats fed other diets.

  12. Food Chromium Contents, Chromium Dietary Intakes And Related Biological Variables In French Free-Living Elderly

    Science.gov (United States)

    Chromium (Cr III), an essential trace element, functions in potentiating insulin sensitivity, regulating glucose homeostasis, improving lipid profile, and maintaining lean body mass. Glucose intolerance and chromium deficiency increase with age, and could be aggravating factors of the metabolic synd...

  13. Soils contaminated with hexavalent chromium

    OpenAIRE

    Fonseca, Bruna Catarina da Silva

    2011-01-01

    Tese de doutoramento em Engenharia Química e Biológica The interest in environmental soil science has been growing in the last years due to the continuous degradation of this major natural resource. With this in mind, and because chromium and lead are two of the most toxic heavy metals frequently detected as soil contaminants in the Portuguese territory, the study and development of few remediation techniques and the indissociable description of the sorption and migration of...

  14. Carbon, chromium and molybdenum contents

    International Nuclear Information System (INIS)

    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

  15. Preparation and Characterization of Nanocrystalline Hard Chromium Coatings Using Eco-Friendly Trivalent Chromium Bath

    OpenAIRE

    V. S. Protsenko; V. O Gordiienko; Danilov, F. I.; Kwon, S.C.

    2011-01-01

    A new aqueous sulfate trivalent chromium bath is described. The chromium bath contains formic acid and carbamide as complexing agents. Chromium was deposited at a temperature of 30÷40 oC and a cathode current density of 10÷25 A dm-2. The bath allows obtaining thick (up to several hundred micrometers) hard chromium coatings with nanocrystalline structure. The electrodeposition rate reaches 0.8÷0.9 µm min-1.

  16. REMOVAL OF HEXAVALENT CHROMIUM FROM DRINKING WATER

    OpenAIRE

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

    2008-01-01

    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 ...

  17. 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.

  18. Inoculation of chromium white cast iron

    OpenAIRE

    D. Kopyciński

    2009-01-01

    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.

  19. Permeation of chromium salts through human skin in vitro

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Fullerton, A; Avnstorp, C;

    1992-01-01

    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...... barrier function of the skin. The amount of chromium found in all skin layers after application of chromium chloride decreased with increasing pH due to lower solubility of the salt. The % of chromium found in the recipient phase as chromium(VI) increased with increasing total chromium concentration...... indicating a limited reduction ability of the skin in vitro....

  20. In situ Carica papaya stem matrix and Fusarium oxysporum (NCBT-156) mediated bioremediation of chromium.

    Science.gov (United States)

    Amatussalam, A; Abubacker, M N; Rajendran, R Babu

    2011-12-01

    Removal of heavy metal chromium was carried out using the fungus Fusarium oxysporum NCBT-156 strain isolated from soil of leather tanning effluent in in situ condition using potassium dichromate solution with 10 per cent Czapek-dox liquid medium. Biosorbent matrix was developed using Carica papaya plant dry stem to colonize the fungal strain to facilitate bioabsorption process. Bioabsorption of chromium was by metabolically mediated intracellular accumulation process. Maximum efficiency of chromium removal by biosorption upto 90 per cent was achieved at the end of 5th day of incubation (120 h of contact time) for 100 and 200 ppm concentration, upto 80 per cent for 300 and 400 ppm, and upto 65 per cent for 500 ppm to 1000 ppm concentrations with pH ranging from 5.8, 5.6, 5.5, 5.4 and 5.2, respectively for 100, 200, 300, 400, 500-1000 ppm concentration. SDS-PAGE protein profile showed significant difference in 34 kDa protein band after chromium absorption by the fungus. FTIR spectroscopic analysis revealed that the main functional groups involved in the uptake of chromium by F. oxysporium strain were carbonyl, carboxyl, amino and hydroxyl groups. PMID:22403866

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

    International Nuclear Information System (INIS)

    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. Alkane dehydrogenation over supported chromium oxide catalysts

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    1999-01-01

    The dehydrogenation of alkanes over supported chromium oxide catalysts in the absence of oxygen is of high interest for the industrial production of propene and isobutene. In this review, a critical overview is given of the current knowledge nowadays available about chromium-based dehydrogenation ca

  3. Study of Chromium Multilayers Properties Obtained by Pulsed Current Density: Residual Stress and Microhardness

    Directory of Open Access Journals (Sweden)

    Julieta TORRES-GONZÁLEZ

    2010-12-01

    Full Text Available Chromium multilayers deposits were obtained from three different bath solutions, they were prepared by switching current density between 10 and 70 Adm-2. Two temperatures were studied, 35°C and 55°C. At 35°C two different microstructures are alternated: columnar obtained at 10 Adm-2 and equiaxial obtained at 70 Adm-2. At 55°C only the columnar type microstructure is present, at 10 and 70 Adm-2, the only difference among the layers is a slight disorientation of grains. The properties of these chromium multilayers were characterized by scanning electron microscopy (SEM and X-ray diffraction (XRD. In general the deposits are microcracked with a high microhardness, high residual stress and a small grain size.

  4. Determination of the total blood volume of the rat using chromium 51 (1962)

    International Nuclear Information System (INIS)

    In various experiments it is important that the rat's blood volume should be known and it is essential that it could be worked out by simply weighing the animal. Therefore authors decided to work out systematically with chromium 51 blood volume for rats with different weights. Results have shown that blood volume for 100 g is 5.55 ml and that it does not seen to vary with the weight of animals. (authors)

  5. Iron(II) modified natural zeolites for hexavalent chromium removal from contaminated water

    OpenAIRE

    Lofù Antonio; Mastrorilli Piero; Dell’Anna Maria Michela; Mali Matilda; Sisto Raffaello; Vignola Rodolfo

    2016-01-01

    Three different types of Fe(II)-modified natural zeolites were tested as supports in continuous-flow columns for the treatment of Cr(VI) contaminated water. The natural zeolites chosen as support were commercially available Zeosand (80% clinoptilolite), ATZ (79% phillipsite/chabazite), and ZS-55RW (90% Chabazite). All the examined modified zeolites turned out active for hexavalent chromium abatement, lowering its concentration below the European regulation level, even at relatively high flow ...

  6. Chemical Stability of Chromium Carbide and Chromium Nitride Powders Compared with Chromium Metal in Synthetic Biological Solutions

    OpenAIRE

    Tao Jiang; Inger Odnevall Wallinder; Gunilla Herting

    2012-01-01

    Chromium carbide (Cr-C) and chromium nitride (Cr-N) powders were compared with a chromium metal powder (Cr-metal) to evaluate their chemical stability in solution. All three powders were exposed in five different synthetic biological solutions of varying pH and chemical composition simulating selected human exposure conditions. Characterisation of the powders, using GI-XRD, revealed that the predominant bulk crystalline phases were Cr7C3 and Cr2N for Cr-C and Cr-N respectively. The outermost ...

  7. 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.

  8. Bainitic chromium-tungsten steels with 3 pct chromium

    International Nuclear Information System (INIS)

    Previous work on 3Cr-1.5MoV (nominally Fe-3Cr-2.5Mo-0.25V-0.1C), 2.25Cr-2W (Fe-2.25Cr-2W-0.1C), and 2.25Cr-2WV (Fe-2.25Cr-2W-0.25V-0.1C) steels indicated that the impact toughness of these steels depended on the microstructure of the bainite formed during continuous cooling from the austenization temperature. Microstructures formed during continuous cooling can differ from classical upper and lower bainite formed during isothermal transformation. Two types of nonclassical microstructures 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 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 2.25Cr-2W and 2.25Cr-2WV steel compositions to increase their hardenability. Charpy testing indicated that the new 3Cr-W and 3Cr-WV steels had improved impact toughness, as demonstrated by lower ductile-brittle transition temperatures and higher upper-shelf energies. This improvement occurred with less tempering than was necessary to achieve similar toughness for the 2.25Cr steels and for high-chromium (9 to 12 pct Cr) Cr-W and Cr-Mo steels

  9. Reproductive toxicological aspects of chromium in males

    International Nuclear Information System (INIS)

    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)

  10. Synthesis of Chromium (Ⅲ) 5-aminosalicylate

    Institute of Scientific and Technical Information of China (English)

    LI Wei; HAO Er-jun; JIANG Yu-qin

    2004-01-01

    As we all known that diabetes is a chronic disease with major health consequences.Research has revealed that the occurrence of diabetes have great thing to do with the chromium deficient. Almost 40 years after the first report of glucose tolerance factor(GTF) [1], no conclusive evidence for an isolable ,biologically active form of chromium exited. Three materials have been proposed to be the biologically active form of chromium: "glucose tolerance factor", chromium Picolinate and low-molecular-weight chromium-binding substance (LWMCr) [2] . So there is potential for the design of new chromium drugs .5-Aminosalicylic acid (5-ASA) is identified as an active component in the therapy of inflammatory bowel disease (IBD) such as Crohn's disease and ulcerative colitis . The therapeutic action of 5-ASA is believed to be coupled to its ability to act as a free radical scavenger [3-4],acting locally on the inflamed colonic mucosa [5-7]. However, the clinical use of 5-ASA is limited, since orally administered 5-ASA is rapidly and completely absorbed from the upper gastrointestinal tract and therefore the local therapeutic effects of 5-ASA in the colon is hardly expected.In this paper, we report the synthesis of chromium(Ⅲ)5-aminosalicylate from 5-ASA and CrCl3. 6H2O.The synthesis route is as follow:The complex has been characterized by elemental analysis, IR spectra, X-ray powder diffractionand TG-DTA . They indicate that the structure is tris(5-ASA) Chromium . Experiments show that thecomplex has a good activity for supplement tiny dietary chromium, lowering blood glucose levels,lowering serum lipid levels and in creasing lean body mass .

  11. 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...

  12. 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...

  13. Chromium intensification of a processed dental radiograph

    International Nuclear Information System (INIS)

    This study was undertaken to determine (1) the usefulness of chromium intensifier to improve the diagnostic quality of light radiograph; (2) the effect of chromium intensifier on density contrast; and (3) the effect of various chemical concentrations on density. The following results obtained: 1. CHROMIUM INTENSIFIER is useful for intensifying and improving the diagnostic quality of a light dental radiograph. 2. The degree of intensification can be controlled by varying bleaching time, repeating the processing, varying the proportions of the potassium bicarbonate and hydrochloric acid solutions. 3. The image produced is black and permanent. 4. The intensifier increases density and contrast

  14. Chromium (VI) adsorption on boehmite

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-03-15

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

  15. Chromium – An essential mineral

    Directory of Open Access Journals (Sweden)

    Merlin D Lindemann

    2009-09-01

    Full Text Available The status of chromium (Cr is not a new question. Cr is clearly an essential nutrient; this is a position that has been held for over three decades by individual scientists, groups of scientists, and governmental committees. The most uniform response across species with regard to Cr deficiency symptoms that are responsive to Cr supplementation are alterations in glucose metabolism with special reference to peripheral tissue sensitivity to insulin. Because the body’s ability to control blood glucose is critical to many life functions, and loss of ability to adequately control blood glucose can lead to many health debilitations, a consequence of Cr supplementation can be improved health and reproductive outcomes as well as improved survival rate or life span.

  16. Occupational asthma due to chromium.

    Science.gov (United States)

    Leroyer, C; Dewitte, J D; Bassanets, A; Boutoux, M; Daniel, C; Clavier, J

    1998-01-01

    We describe a 28-year-old subject employed as a roofer in a construction company since the age of 19, who developed work-related symptoms of a cough, shortness of breath, wheezing, rhinitis and headaches. A description of a usual day at work suggested that the symptoms worsened while he was sawing corrugated fiber cement. Baseline spirometry was normal, and there was a mild bronchial hyperresponsiveness to carbachol. A skin patch test to chromium was negative. A specific inhalation challenge showed a boderline fall in forced expiratory volume in 1 s (FEV1) after exposure to fiber cement dust. Exposure to nebulization of potassium dichromate (K2Cr2O7), at 0.1 mg.ml-1 for 30 min, was followed by an immediate fall by 20% FEV1. Simultaneously, a significant increase in bronchial hyperresponsiveness was demonstrated. PMID:9782225

  17. 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....... Processes that potentially fractionate Cr isotopes, perhaps during deposition, burial and alteration need to be constrained.Previous studies have shown that Cr isotopes are fractionated during oxidative weathering on land, where heavy Cr isotopes are preferentially removed with Cr(VI) while residual soils...... retain an isotopically light Cr signature. Cr(VI) enriched in heavy Cr isotopes is then transported via river waters to the oceans and sequestered into marine sediments. Marine chemical sediments such asbanded iron formations and modern marine carbonates have proven useful in recording the Cr isotope...

  18. 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 sp....... The detection limit was 0.5 micrograms l-1 for both species. Data were in agreement with Zeeman-effect background corrected atomic absorption spectrometry measurements....

  19. AEROSOL BEHAVIOR IN CHROMIUM WASTE INCINERATION

    Institute of Scientific and Technical Information of China (English)

    Suyuan Yu

    2003-01-01

    Cr2O3 is considered as the dominant incineration product during the combustion disposal of chromium waste. A hydrogen/air diffusion flame was employed to simulate the industrial process of incineration. Cr2O3 aerosols were generated inside the flame by the gas phase reaction of chromium and oxygen. Chromium came from the rapid decomposition of chromium hexacarbonyl (Cr(CO)6) at room temperature and was carried into the combustion chamber by hydrogen. Aerosol and clusters can then be easily formed in the flame by nucleation and coagulation. A two dimensional Discrete-Sectional Model (DSM) was adopted to calculate the Cr2O3 aerosol behavior. The experimental measurement method was Dynamic Light Scattering. The numerically predicted results agreed well with those of the experimental measurement. Both results show that the Cr2O3 aerosol size reached about 70 nanometers at the flame top.

  20. Potentiometry: A Chromium (III) -- EDTA Complex

    Science.gov (United States)

    Hoppe, J. I.; Howell, P. J.

    1975-01-01

    Describes an experiment that involves the preparation of a chromium (III)-EDTA compound, a study of its infrared spectrum, and the potentiometric determination of two successive acid dissociation constants. (Author/GS)

  1. Bioremediation of chromium solutions and chromium containing wastewaters.

    Science.gov (United States)

    Malaviya, Piyush; Singh, Asha

    2016-08-01

    Cr(VI) represents a serious threat to human health, living resources and ecological system as it is persistent, carcinogenic and toxic, whereas, Cr(III), another stable oxidation state of Cr, is less toxic and can be readily precipitated out of solution. The conventional methods of Cr(VI) removal from wastewaters comprise of chemical reduction followed by chemical precipitation. However, these methods utilize large amounts of chemicals and generate toxic sludge. This necessitates the need for devising an eco-technological strategy that would use the untapped potential of the biological world for remediation of Cr(VI) containing wastewaters. Among several viable approaches, biotransformation of Cr(VI) to relatively non-toxic Cr(III) by chromium resistant bacteria offers an economical- and environment-friendly option for its detoxification. Various studies on use of Cr(VI) tolerant viable bacterial isolates for treatment of Cr(VI) containing solutions and wastewater have been reported. Therefore, a detailed account of mechanisms and processes involved in bioreduction of Cr(VI) from solutions and wastewaters by bacterial isolates are the focus of this review article in addition to a discussion on toxicity of Cr(VI) on bacterial strains and various factors affecting Cr(VI) bioreduction. PMID:25358056

  2. 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.

  3. Lateral stress evolution in chromium sulfide cermets with varying excess chromium

    Science.gov (United States)

    Petel, O. E.; Appleby-Thomas, G. J.; Wood, D. C.; Capozzi, A.; Nabavi, A.; Goroshin, S.; Frost, D. L.; Hazell, P. J.

    2016-04-01

    The shock response of chromium sulfide-chromium, a cermet of potential interest as a matrix material for ballistic applications, has been investigated at two molar ratios. Using a combustion synthesis technique allowed for control of the molar ratio of the material, which was investigated under near-stoichiometric (cermet) and excess chromium (interpenetrating composite) conditions, representing chromium:sulfur molar ratios of 1.15:1 and 4:1, respectively. The compacts were investigated via the plate-impact technique, which allowed the material to be loaded under a one-dimensional state of strain. Embedded manganin stress gauges were employed to monitor the temporal evolution of longitudinal and lateral components of stress in both materials. Comparison of these two components has allowed assessment of the variation of material shear strength both with impact pressure/strain-rate and time for the two molar ratio conditions. The two materials exhibited identical material strength despite variations in their excess chromium contents.

  4. The enriched chromium neutrino source for GALLEX

    International Nuclear Information System (INIS)

    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

  5. Serum chromium levels in gestational diabetes mellitus

    Directory of Open Access Journals (Sweden)

    P G Sundararaman

    2012-01-01

    Full Text Available Objective: To measure serum chromium level in women with gestational diabetes mellitus (GDM from Chennai, South India. Materials and Methods: Thirty women with gestational diabetes, 60 age matched controls. Inclusion criteria: Gestational age 22-28 weeks, age group 20-35 years. Exclusion Criteria: Gestational age beyond 28 weeks, malnutrition or presence of infection. Serum chromium was measured using inductive couple plasma emission spectrometer. Results: Serum chromium levels of women with GDM, 1.59+/-0.02 ng/ml (range: 0.16-4.0 ng/ml were lower than in controls (4.58+/-0.62 ng/ml; range 0.82-5.33 ng/ml (P < 0.001. However, there were no significant differences among cases and controls when subdivided by parity. Conclusions: Women with GDM from a South Indian city had lower levels of serum chromium compared to pregnant women without GDM. Studies may be done whether chromium supplementation is useful in this group of women.

  6. Occupational exposure to chromium(VI compounds

    Directory of Open Access Journals (Sweden)

    Jolanta Skowroń

    2015-07-01

    Full Text Available This article discusses the effect of chromium(VI (Cr(VI on human health under conditions of acute and chronic exposure in the workplace. Chromium(VI compounds as carcinogens and/or mutagens pose a direct danger to people exposed to them. If carcinogens cannot be eliminated from the work and living environments, their exposure should be reduced to a minimum. In the European Union the proposed binding occupational exposure limit value (BOELV for chromium(VI of 0.025 mg/m³ is still associated with high cancer risk. Based on the Scientific Commitee of Occupational Exposure Limits (SCOEL document chromium(VI concentrations at 0.025 mg/m³ increases the risk of lung cancer in 2–14 cases per 1000 exposed workers. Exposure to chromium(VI compounds expressed in Cr(VI of 0.01 mg Cr(VI/m3 is responsible for the increased number of lung cancer cases in 1–6 per 1000 people employed in this condition for the whole period of professional activity. Med Pr 2015;66(3:407–427

  7. [Occupational exposure to chromium(VI) compounds].

    Science.gov (United States)

    Skowroń, Jolanta; Konieczko, Katarzyna

    2015-01-01

    This article discusses the effect of chromium(VI) (Cr(VI)) on human health under conditions of acute and chronic exposure in the workplace. Chromium(VI) compounds as carcinogens and/or mutagens pose a direct danger to people exposed to them. If carcinogens cannot be eliminated from the work and living environments, their exposure should be reduced to a minimum. In the European Union the proposed binding occupational exposure limit value (BOELV) for chromium(VI) of 0.025 mg/m³ is still associated with high cancer risk. Based on the Scientific Commitee of Occupational Exposure Limits (SCOEL) document chromium(VI) concentrations at 0.025 mg/m³ increases the risk of lung cancer in 2-14 cases per 1000 exposed workers. Exposure to chromium(VI) compounds expressed in Cr(VI) of 0.01 mg Cr(VI)/m3; is responsible for the increased number of lung cancer cases in 1-6 per 1000 people employed in this condition for the whole period of professional activity. PMID:26325053

  8. Liquid-liquid extraction of chromium (VI) from sulfuric acid solutions using tri-n-dodecylamine/kerosene

    International Nuclear Information System (INIS)

    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)2SO4 TDAHHSO4 and (TDAH)2 Cγ2O7 at 25 Centigrade and have been found to be K1=109.642(14/mol4), K2= 10-0.899(L/mol) and Kex 1010.55 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. Flashlamp-pumped lasing of chromium-doped GSG garnet

    International Nuclear Information System (INIS)

    The implications for the practical use of chromium:GSGG in lamp-pumped tunable lasers are discussed in this paper. The authors report here some major improvements in the performance of the flashlamp-pumped chromium:GSGG laser

  10. Surface Chemistry and Spectroscopy of Chromium in Inorganic Oxides

    OpenAIRE

    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.

  11. TA-55 change control manual

    Energy Technology Data Exchange (ETDEWEB)

    Blum, T.W.; Selvage, R.D.; Courtney, K.H.

    1997-11-01

    This manual is the guide for initiating change at the Plutonium Facility, which handles the processing of plutonium as well as research on plutonium metallurgy. It describes the change and work control processes employed at TA-55 to ensure that all proposed changes are properly identified, reviewed, approved, implemented, tested, and documented so that operations are maintained within the approved safety envelope. All Laboratory groups, their contractors, and subcontractors doing work at TA-55 follow requirements set forth herein. This manual applies to all new and modified processes and experiments inside the TA-55 Plutonium Facility; general plant project (GPP) and line item funded construction projects at TA-55; temporary and permanent changes that directly or indirectly affect structures, systems, or components (SSCs) as described in the safety analysis, including Facility Control System (FCS) software; and major modifications to procedures. This manual does not apply to maintenance performed on process equipment or facility SSCs or the replacement of SSCs or equipment with documented approved equivalents.

  12. TA-55 change control manual

    International Nuclear Information System (INIS)

    This manual is the guide for initiating change at the Plutonium Facility, which handles the processing of plutonium as well as research on plutonium metallurgy. It describes the change and work control processes employed at TA-55 to ensure that all proposed changes are properly identified, reviewed, approved, implemented, tested, and documented so that operations are maintained within the approved safety envelope. All Laboratory groups, their contractors, and subcontractors doing work at TA-55 follow requirements set forth herein. This manual applies to all new and modified processes and experiments inside the TA-55 Plutonium Facility; general plant project (GPP) and line item funded construction projects at TA-55; temporary and permanent changes that directly or indirectly affect structures, systems, or components (SSCs) as described in the safety analysis, including Facility Control System (FCS) software; and major modifications to procedures. This manual does not apply to maintenance performed on process equipment or facility SSCs or the replacement of SSCs or equipment with documented approved equivalents

  13. Proposing and evaluating applications for products obtained during chromium chip alkaline hydrolysis produced during leather tanning

    Directory of Open Access Journals (Sweden)

    Andrea Díaz

    2010-04-01

    Full Text Available Some applications for products obtained by chromium chip alkaline hydrolysis produced during leather tanning were evaluated in this work, considering the concept of maximising tanneries’ solid residue reuse for different industrial applications and minimising the environmental impact so produced. When Cr(OH is transformed into Cr (OH(SO it can be used in tanning leather (i.e. as tanning salt. When compared to commercial salts, 2 4 it was determined that it could be applied to mixtures containing this salt, replacing it by up to 40%. Chromium content reduction was evaluated for collagen hydrolyzate by pH control after alkaline hydrolysis of the chips and by applying adsorbent materials such as bentonite, alfalfa and sorghum biomass and activated charcoal, a maximum 55% Cr removal being obtained when the first two adsorbent materials were used.

  14. Studies of Some Novel Chromium Pyridine Dicarboxylate Complexes

    OpenAIRE

    Chauhan Jayprakash S; Patel Rameshchandra P; Pandya Ajit V

    2014-01-01

    Chromium pyridine di-carboxylate complexes are synthesized from Chromium (III) with pyridine 2, 6- dicarboxylic acid, pyridine 2, 3 and 2, 5- dicarboxylic acids. Chromium forms colored complexes. Chromium (III) forms a violate complex with pyridine 2, 6- dicarboxylic acid and purple violate complex with pyridine 2, 3 and 2, 5- dicarboxylic acids. The job’s method indicates metal ligand ratio to be 1:2. The interpretation of UV-VIS spectra indicates octahedral geometry and IR spectra give clue...

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

    International Nuclear Information System (INIS)

    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)

  16. 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...

  17. 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...

  18. 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...

  19. Thermodynamic properties of chromium bearing slags and minerals. A review

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Yanping; Holappa, L.

    1996-12-31

    In this report, the thermodynamic properties of chromium bearing slags and minerals were reviewed based on the available information in the literature. It includes the analysing methods for oxidation state of chromium in slags, oxidation state of chromium and activities of chromium oxides in slags and minerals. The phase diagrams of chromium oxide systems and chromium distributions between slag and metal phases are also covered ill this review. Concerning the analysing methods, it was found that most of the available approaches are limited to iron free slag systems and the sample preparation is very sensitive to the analysing results. In silicate slags under reducing atmosphere, divalent and trivalent chromium co-exist in the slags. It is agreed that the fraction of divalent chromium to total chromium increases with higher temperature, lower slag basicity and oxygen potential. For the slags under oxidising atmosphere, trivalent, pentavalent and hexavalent states were reported to be stable. The activities of CrO and CrO{sub 1.5} were concluded to have positive deviation from ideal solution. Slag basicity has a positive effect and temperature has a negative effect on the activities of chromium oxides. The phase diagrams of the Cr-O, binary, and ternary chromium containing oxide systems have been examined systematically. The analysis shows that the data on the quaternary and quinary systems are insufficient, and require further investigation. The most important features of the chromium containing silicate slags are the large miscibility gaps and the stability of the chromite spinel. (orig.) (76 refs.)

  20. 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...

  1. Hexavalent and trivalent chromium in leather: What should be done?

    Science.gov (United States)

    Moretto, Angelo

    2015-11-01

    Trivalent chromium compounds are used for leather tanning, and chromium may be released during use of leather goods. In certain instances, small amounts of hexavalent chromium can be formed and released. Both trivalent and hexavalent chromium can elicit allergic skin reaction in chromium sensitised subjects, the latter being significantly more potent. Induction of sensitisation only occurs after exposure to hexavalent chromium. A minority of subjects are sensitised to chromium, and in a fraction of these subjects allergic skin reaction have been described after wearing leather shoes or, less frequently, other leather goods. The evidence that in all these cases the reaction is related to hexavalent chromium is not always strong. The content of hexavalent chromium in leather is regulated in European Union, but rate of release rather than content is relevant for allergic skin reaction. The role of trivalent chromium appear much less relevant if at all. Modern tanning procedure do not pose significant risk due to either hexavalent or trivalent chromium. Dismissing bad quality and worn-off leather goods is relevant in reducing or eliminating the skin reaction. It should also be pointed out that shoe components or substances other than chromium in leather may cause allergic/irritative skin reactions. PMID:26361854

  2. SAFETY OF TRIVALENT CHROMIUM COMPLEXES USED IN NUTRIENT SUPPLEMENTS

    Science.gov (United States)

    Toxicity studies regarding trivalent chromium have often been completed under conditions that are not designed to reflect conditions that would be encountered under normal physiological conditions. We have shown that the incorporation of chromium into tissues of rats from chromium chloride and chro...

  3. Strategies for chromium bioremediation of tannery effluent.

    Science.gov (United States)

    Garg, Satyendra Kumar; Tripathi, Manikant; Srinath, Thiruneelakantan

    2012-01-01

    Bioremediation offers the possibility of using living organisms (bacteria, fungi, algae,or plants), but primarily microorganisms, to degrade or remove environmental contaminants, and transform them into nontoxic or less-toxic forms. The major advantages of bioremediation over conventional physicochemical and biological treatment methods include low cost, good efficiency, minimization of chemicals, reduced quantity of secondary sludge, regeneration of cell biomass, and the possibility of recover-ing pollutant metals. Leather industries, which extensively employ chromium compounds in the tanning process, discharge spent-chromium-laden effluent into nearby water bodies. Worldwide, chromium is known to be one of the most common inorganic contaminants of groundwater at pollutant hazardous sites. Hexavalent chromium poses a health risk to all forms of life. Bioremediation of chromium extant in tannery waste involves different strategies that include biosorption, bioaccumulation,bioreduction, and immobilization of biomaterial(s). Biosorption is a nondirected physiochemical interaction that occurs between metal species and the cellular components of biological species. It is metabolism-dependent when living biomass is employed, and metabolism-independent in dead cell biomass. Dead cell biomass is much more effective than living cell biomass at biosorping heavy metals, including chromium. Bioaccumulation is a metabolically active process in living organisms that works through adsorption, intracellular accumulation, and bioprecipitation mechanisms. In bioreduction processes, microorganisms alter the oxidation/reduction state of toxic metals through direct or indirect biological and chemical process(es).Bioreduction of Cr6+ to Cr3+ not only decreases the chromium toxicity to living organisms, but also helps precipitate chromium at a neutral pH for further physical removal,thus offering promise as a bioremediation strategy. However, biosorption, bioaccumulation, and

  4. Collisional properties of trapped cold chromium atoms

    CERN Document Server

    Pavlovich, Z; Côté, R; Sadeghpour, H R; Pavlovic, Zoran; Roos, Bjoern O.; Côté, Robin

    2004-01-01

    We report on calculations of the elastic cross section and thermalization rate for collision between two maximally spin-polarized chromium atoms in the cold and ultracold regimes, relevant to buffer-gas and magneto-optical cooling of chromium atoms. We calculate ab initio potential energy curves for Cr2 and the van der Waals coefficient C6, and construct interaction potentials between two colliding Cr atoms. We explore the effect of shape resonances on elastic cross section, and find that they dramatically affect the thermalization rate. Our calculated value for the s-wave scattering length is compared in magnitude with a recent measurement at ultracold temperatures.

  5. Influence of nitrogen on the structure and properties of chromium, chromium-molybdenum and chromium-manganese steels

    International Nuclear Information System (INIS)

    Phase transformations, precipitation processes and properties of the chromium, chromium-molybdenum and chromium-manganese steels with a high content of nitrogen as the dependence on thermal treatment were investigated. In case of Fe-0.08C-18Cr-18Mn-N and Fe-0.08C-18Cr-18Mn-2Mo-N steels the samples in the state after solution at temperature 1050oC and 1150oC and 1250oC and after subsequent annealing in 600oC and 800oC were investigated. heat treatment of the Fe-0.5C-10Cr-N and Fe-0.5C-10Cr-1Mo-N steels included austenitizment from 1000oC with air cooling and hardening from 1000oC with oil cooling and tempering in 650oC and 750oC in two hours with cooling in the air. These investigations show that the influence of nitrogen as an alloy element on the phase transformations, precipitation processes, mechanical and corrosion properties is connected with the presence of molybdenum and chromium in the steel. Nitrogen with these elements creates complex ions with the coordinate number 6. This statement is formed on the base of both calculations and investigation results. (author)

  6. High-Quality Draft Genome Sequence of Leucobacter sp. Strain G161, a Distinct and Effective Chromium Reducer

    OpenAIRE

    Ge, Shimei; Ai, Wenjing; Dong, Xinjiao

    2016-01-01

    Here, we report the genome sequence for Leucobacter sp. strain G161 due to its distinct and effective hexavalent chromium reduction under aerobic growth conditions, followed by facultative anaerobic incubation. The draft genome sequence of Leucobacter sp. G161 comprises 3,554,188 bp, with an average G+C content of 65.3%, exhibiting 3,341 protein-coding genes and 55 predicted RNA genes.

  7. Electrodeposition of black chromium thin films from trivalent chromium-ionic liquid solution

    OpenAIRE

    Eugénio, S.; Vilar, Rui; C. M. Rangel; Baskaran, I.

    2009-01-01

    In the present study, black chromium thin films were electrodeposited from a solution of 1-butyl-3- methylimidazolium tetrafluoroborate ([BMIm][BF4] ionic liquid containing trivalent chromium (Cr(III)). Homogeneous and well adherent coatings have been obtained on nickel, copper and stainless steel substrates. The nucleation and growth of the films were investigated by cyclic voltammetry and current-density/time transient techniques. SEM/EDS, XPS and XRD were used to study the morphology, chem...

  8. Reduction of Hexavalent Chromium by Viable Cells of Chromium Resistant Bacteria Isolated from Chromite Mining Environment

    OpenAIRE

    Satarupa Dey; Baishali Pandit; A. K. Paul

    2014-01-01

    Environmental contamination of hexavalent chromium [Cr(VI)] is of serious concern for its toxicity as well as mutagenic and carcinogenic effects. Bacterial chromate reduction is a cost-effective technology for detoxification as well as removal of Cr(VI) from polluted environment. Chromium resistant and reducing bacteria, belonging to Arthrobacter, Pseudomonas, and Corynebacterium isolated from chromite mine overburden and seepage samples of Orissa, India, were found to tolerate 12–18 mM Cr(VI...

  9. Reduction of Chromium-VI by Chromium Resistant Lactobacilli: A Prospective Bacterium for Bioremediation

    OpenAIRE

    Mishra, Ritesh; Sinha, Vartika; Kannan, Ambrose; Upreti, Raj K.

    2012-01-01

    Chromium is a toxic heavy metal, which primarily exists in two inorganic forms, Cr (VI) and Cr (III). Highly soluble hexavalent chromium is carcinogenic due to its oxidizing nature. It is well established that the intestinal bacteria including Lactobacilli have regulatory effect on intestinal homeostasis and a breakdown in the relationship between intestinal cells and bacteria results in the manifestation of gastrointestinal (GI) disorders. In this study Cr (VI) resistance was developed in La...

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

    OpenAIRE

    Mirković Nemanja

    2007-01-01

    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 experimenta...

  11. Chromium-manganese steels of transition class

    International Nuclear Information System (INIS)

    Possibilities of nickel replacing by manganese and preparing the same level of mechanical properties as in chromium-nickel steels due to γ-α transformations taking place during property tests, are studied. Chromium-manganese steels with the composition of 0.05-0.1%C, 13-14%Cr, 5.0-6.5%Mn, 0.2-0.5%Si, 0.03-0.13%N, 0.05-0.01%Al and additionally alloyed 0.3-2.0%Cu, 0.05-0.6%V, 0.3-1.0%Mo, 0.02-0.05%Ca in various combinations have been melted. It is shown, that using alloying and heat treatment one can control the phase composition, austenite resistance to martensite transformation during loading and mechanical properties of chromium-manganese steels of the transition class. The use of the phase transformation in the process of testing determines the level of mechanical properties. The optimum development of the transformation accompanied by a sufficient development of processes of hardening and microstresses relaxation permits to obtain a high level of mechanical properties: σsub(B)=1500 MPa, σsub(0.2)-1130MPa, delta=15%, psi=37%, asub(H)=1000 kJ/msup(2) which exceeds the level for chromium-nickel steels. Steels have a lower cost and do not require any complecated heat treatment regime

  12. Defect structure of electrodeposited chromium layers

    International Nuclear Information System (INIS)

    Positron annihilation spectroscopy was applied to study the effects of pre-treatment and composition of substrates on the quality and defect structure of electrodeposited thick chromium coatings. The results show that both parameters are important, and a scenario is proposed why the mechanically polished substrate gives more defective film than the electro polished one.

  13. Defect structure of electrodeposited chromium layers

    CERN Document Server

    Marek, T; Vertes, A; El-Sharif, M; McDougall, J; Chisolm, C U

    2000-01-01

    Positron annihilation spectroscopy was applied to study the effects of pre-treatment and composition of substrates on the quality and defect structure of electrodeposited thick chromium coatings. The results show that both parameters are important, and a scenario is proposed why the mechanically polished substrate gives more defective film than the electro polished one.

  14. Flashlamp-pumped lasing of chromium: GSGG

    International Nuclear Information System (INIS)

    Lasing action in chromium-doped gadolinium scandium gallium garnet (Cr:GSGG) is well established for both CW/sup (1)/ and flashlamp/sup (2)/ pumping. This paper describes an investigation of flashlamp-pumped Cr:GSGG lasers and indicates some of the factors which limit performance

  15. Trace Elements Excluding Iron - Chromium and Zinc

    Science.gov (United States)

    The percentage of middle-aged US adults who are participating in leisure-time physical activities is growing. These adults also seek credible information about specific supplements that the public press routinely describes as necessary to enable increases in physical performance. Chromium and zinc a...

  16. HEALTH ASSESSMENT DOCUMENT FOR CHROMIUM. FINAL REPORT

    Science.gov (United States)

    The full document represents a comprehensive data base that considers all sources of chromium in the environment, the likelihood for its exposure to humans, and the possible consequences to man and lower organisms from its absorption. This information is integrated into a format ...

  17. 29 CFR 1926.1126 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... CFR 1926.51 Where skin contact with chromium (VI) occurs, the employer shall provide washing facilities in conformance with 29 CFR 1926.51. Eating and drinking areas provided by the employer shall also... requirements of the Hazard Communication Standard, 29 CFR 1910.1200. (3) Cleaning and replacement. (i)...

  18. 29 CFR 1910.1026 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... CFR 1910.141. Where skin contact with chromium (VI) occurs, the employer shall provide washing facilities in conformance with 29 CFR 1910.141. Eating and drinking areas provided by the employer shall also... requirements of the Hazard Communication Standard, 29 CFR 1910.1200. (3) Cleaning and replacement. (i)...

  19. 29 CFR 1915.1026 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... CFR 1910.141. Where skin contact with chromium (VI) occurs, the employer shall provide washing facilities in conformance with 29 CFR 1915.97. Eating and drinking areas provided by the employer shall also... requirements of the Hazard Communication Standard, 29 CFR 1910.1200. (3) Cleaning and replacement. (i)...

  20. Chromium(III) and chromium(VI) surface treated galvanized steel for outdoor constructions: environmental aspects.

    Science.gov (United States)

    Lindström, David; Hedberg, Yolanda; Odnevall Wallinder, Inger

    2010-06-01

    The long-term degradation of chromium(III) (Zn-Cr(III)) and chromium(VI)-based (Zn-Cr(VI)) surface treatments on galvanized steel and their capacities to hinder the release of zinc induced by atmospheric corrosion at nonsheltered urban and marine exposure conditions for 2 years are investigated. Compared to bare zinc sheet, both surface treatments revealed high corrosion protection abilities and capacities to hinder the release of zinc, still evident after 2 years of exposure. The zinc barrier properties of the thinner Zn-Cr(VI) (10 nm) treatment were during the first 100 days of urban exposure slightly improved compared with Zn-Cr(III) (35 nm). However, their long-term protection capacities were inverse. Released concentrations of total chromium correspond to annual release rates less than 0.000032 (Zn-Cr(III)) and 0.00014 g Cr m(-2) yr(-1) (Zn-Cr(VI)) after 1 year of urban exposure. Aging by indoor storage of the surface treatments prior to outdoor exposure reduced the released Cr concentrations from the surface treatments. No Cr(VI) was released from the aged surfaces but from the freshly exposed Zn-Cr(VI). Marine exposure conditions resulted in a faster reduction of chromate to chromium(III)oxide compared with urban conditions, and a significantly lower amount of both chromium(III) and chromium(VI) released from Zn-Cr(VI) at the marine site compared with the urban site. PMID:20462267

  1. Biological groundwater treatment for chromium removal at low hexavalent chromium concentrations.

    Science.gov (United States)

    Mamais, Daniel; Noutsopoulos, Constantinos; Kavallari, Ioanna; Nyktari, Eleni; Kaldis, Apostolos; Panousi, Eleni; Nikitopoulos, George; Antoniou, Kornilia; Nasioka, Maria

    2016-06-01

    The objective of this work is to develop and evaluate biological groundwater treatment systems that will achieve hexavalent chromium reduction and total chromium removal from groundwater at hexavalent chromium (Cr(VI)) groundwater concentrations in the 0-200 μg/L range. Three lab-scale units operated, as sequencing batch reactors (SBR) under aerobic, anaerobic and anaerobic-aerobic conditions. All systems received groundwater with a Cr(VI) content of 200 μg/L. In order to support biological growth, groundwater was supplemented with milk, liquid cheese whey or a mixture of sugar and milk to achieve a COD concentration of 200 mg/L. The results demonstrate that a fully anaerobic system or an anaerobic-aerobic system dosed with simple or complex external organic carbon sources can lead to practically complete Cr(VI) reduction to Cr(III). The temperature dependency of maximum Cr(VI) removal rates can be described by the Arrhenius relationship. Total chromium removal in the biological treatment systems was not complete because a significant portion of Cr(III) remained in solution. An integrated system comprising of an anaerobic SBR followed by a sand filter achieved more than 95% total chromium removal thus resulting in average effluent total and dissolved chromium concentrations of 7 μg/L and 3 μg/L, respectively. PMID:26971177

  2. Nephrotoxic and hepatotoxic effects of chromium compounds in rats

    Energy Technology Data Exchange (ETDEWEB)

    Laborda, R.; Diaz-Mayans, J.; Nunez, A.

    1986-03-01

    The nephrotoxic, hepatotoxic and cardiotoxic actions of hexavalent chromium compounds, as well as their effects on lung, blood and circulation may contribute to the fatal outcome of chromium intoxication. Although trivalent chromium have been regarded as relatively biologically inert, there are a few salts of chromium III that have been found to be carcinogenic when inhaled, ingested or brought in contact with the tissues. Sensitive persons and industry workers have been subjects of dermatitis, respiratory tract injuries and digestive ulcers due to chromium compounds. In this work, the authors have studied the effect of trivalent and hexavalent chromium compounds on rats measuring the transaminases (GOT and GPT), urea and creatinine levels in serum of chromium poisoned animals at different times.

  3. A Kinetic Model of Chromium in a Flame

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Chromium has been identified as a carcinogenic metal.Incineration is the useful method for disposal of toxic chromium hazard waste and a chromium kinetic model in a flame is very important to study chromium oxidation.Chromium chemical kinetics over a range of temperatures of a hydrogen/air flame is proposed.Nine chromium compounds and fifty-eight reversible chemical reactions were considered The forward reaction rates are calculated based on the molecular collision approach for unknown ones and Arrhenius's Law for known ones.The backward reaction rates were calculated according to forward reaction rates, the equilibrium constants and chemical thermodynamics.It is verified by several equilibrium cases and is tested by a hydrogen/air diffusion flame.The results show that the kinetic model could be used in cases in which the chromium kinetics play an important role in a flame

  4. The Chromium is an essential element in the human

    International Nuclear Information System (INIS)

    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)

  5. Reaction of chromium(VI) with glutathione or with hydrogen peroxide: identification of reactive intermediates and their role in chromium(VI)-induced DNA damage.

    OpenAIRE

    Aiyar, J; Berkovits, H J; Floyd, R A; Wetterhahn, K E

    1991-01-01

    The types of reactive intermediates generated upon reduction of chromium(VI) by glutathione or hydrogen peroxide and the resulting DNA damage have been determined. In vitro, reaction of chromium(VI) with glutathione led to formation of two chromium(V) complexes and the glutathione thiyl radical. When chromium(VI) was reacted with DNA in the presence of glutathione, chromium-DNA adducts were obtained, with no DNA strand breakage. The level of chromium-DNA adduct formation correlated with chrom...

  6. The Incorporation of Chromium in Rice Straw Fermented with Ganoderma lucidum

    Directory of Open Access Journals (Sweden)

    F. Agustin

    2013-04-01

    Full Text Available The research was designed to evaluate chromium incorporation by Ganoderma lucidum in rice straw substrate supplemented with chromium chloride. Treatments were combination of Cr level (0, 500, 1000, 1500, 2000, 25000, and 3000 ppm and fermentation time (0, 2, 3, and 4 wk. The treatments were arranged in a factorial 7 x 4 and allocated in completely randomized design with three replications. G. lucidum was grown in potato dextrose agar (PDA medium for 10 days and was inoculated to the substrate which have been sterilized and mixed with CrCl3.6H2O. The moisture of substrate was maintained at 70%. Fiber and protein components of growth media of G. lucidum was determined and analyzed for their Cr content. The finding result showed that addition of Cr up to 3000 ppm into the substrate stimulated the G. lucidum growth. Chromium was incorporated into the fiber and protein components of the growth substrate of G. lucidum during fermentation. Incorporation of Cr into the protein of substrate containing 3000 ppm Cr was highest when fermented for 4 wk. Protein component of substrate contained 9.29% Cr while in NDF and ADF was 27.20% and 10.55% Cr, respectively. It is concluded that Cr was incorporated into the G. lucidum cells during fermentation.

  7. Sliding wear studies of sprayed chromium carbide-nichrome coatings for gas-cooled reactor applications

    International Nuclear Information System (INIS)

    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 8160C 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

  8. 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. PMID:26477944

  9. 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%.

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

    International Nuclear Information System (INIS)

    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-Cr2O3 layer at the surface; higher is the input laser power, enhanced is the crystallinity of the α-Cr2O3 layer. The α-Cr2O3 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%

  11. Production of basic chromium sulfate by using recovered chromium from ashes of thermally treated leather.

    Science.gov (United States)

    Dettmer, Aline; Nunes, Keila Guerra Pacheco; Gutterres, Mariliz; Marcílio, Nilson Romeu

    2010-04-15

    Leather wastes tanned with chromium are generated during the production process of leather, hence the wastes from hand crafted goods and footwear industries are a serious environmental problem. The thermal treatment of leather wastes can be one of the treatment options because the wastes are rich in chromium and can be used as a raw material for sodium chromate production and further to obtain several chromium compounds. The objective of this study was to utilize the chromium from leather wastes via basic chromium sulfate production to be subsequently applied in a hide tanning. The obtained results have shown that this is the first successful attempt to achieve desired base properties of the product. The result was achieved when the following conditions were applied: a molar ratio between sodium sulfite and sodium dichromate equal to 6; reaction time equal to 5 min before addition of sulfuric acid; pH of sodium dichromate solution equal to 2. Summarizing, there is an opportunity to utilize the dangerous wastes and reused them in the production scheme by minimizing or annulling the environmental impact and to attend a sustainable process development concept. PMID:20031309

  12. Inelastic Scattering of Neutrons in Chromium

    International Nuclear Information System (INIS)

    The phonon spectrum of chromium has been studied by neutron inelastic scattering. The dispersion curves are very similar, in form to those of tungsten and molybdenum, indicating similar interionic force constants. The neutron groups broaden but do not shift appreciably when the temperature is raised. No effect has been observed which can be attributed to the interaction between the phonons and the crystal magnetization in the antiferromagnetic phase. (author)

  13. Observational Approach to Chromium Site Remediation - 13266

    International Nuclear Information System (INIS)

    Production reactors at the U.S. Department of Energy's (DOE) Hanford Site in Richland, Washington, required massive quantities of water for reactor cooling and material processing. To reduce corrosion and the build-up of scale in pipelines and cooling systems, sodium dichromate was added to the water feedstock. Spills and other releases at the makeup facilities, as well as leaks from miles of pipelines, have led to numerous areas with chromium-contaminated soil and groundwater, threatening fish populations in the nearby Columbia River. Pump-and-treat systems have been installed to remove chromium from the groundwater, but significant contamination remain in the soil column and poses a continuing threat to groundwater and the Columbia River. Washington Closure Hanford, DOE, and regulators are working on a team approach that implements the observational approach, a strategy for effectively dealing with the uncertainties inherent in subsurface conditions. Remediation of large, complex waste sites at a federal facility is a daunting effort. It is particularly difficult to perform the work in an environment of rapid response to changing field and contamination conditions. The observational approach, developed by geotechnical engineers to accommodate the inherent uncertainties in subsurface conditions, is a powerful and appropriate method for site remediation. It offers a structured means of quickly moving into full remediation and responding to the variations and changing conditions inherent in waste site cleanups. A number of significant factors, however, complicate the application of the observational approach for chromium site remediation. Conceptual models of contamination and site conditions are difficult to establish and get consensus on. Mid-stream revisions to the design of large excavations are time-consuming and costly. And regulatory constraints and contract performance incentives can be impediments to the flexible responses required under the observational

  14. Stainless chromium-nickel steels. Chapter I

    International Nuclear Information System (INIS)

    The chemical composition is tabulated of 90 chromium-nickel stainless steels and alloys given in volume %. The values are also given of the corrosion resistance of the steels and alloys. The tables show data on the surface condition or the methods of material working, types and chemical composition of the medium where corrosion resistance tests were carried out, temperature, pressure, time of tests, corrosion rates, corrosion types, and literature references. A total of 35 references is given. (J.B.)

  15. Loading chromium atoms in a magnetic guide

    OpenAIRE

    Greiner, A; Sebastian, J.; Rehme, P.; Aghajani-Talesh, A.; Griesmaier, A.; Pfau, T.

    2007-01-01

    We have realized a magnetic guide for ultracold chromium atoms by continuously loading atoms directly from a Zeeman slower into a horizontal guide. We observe an atomic flux of $2 \\cdot 10^7$ atoms/s and are able to control the mean velocity of the guided atoms between 0 m/s and 3 m/s. We present our experimental results on loading and controlling the mean velocity of the guided atoms and discuss the experimental techniques that are used.

  16. X-616 Chromium Sludge Lagoons pictorial overview, Piketon, Ohio

    International Nuclear Information System (INIS)

    The Portsmouth Gaseous Diffusion Plant uses large quantities of water for process cooling. The X-616 Liquid Effluent Control Facility was placed in operation in December 1976 to treat recirculation cooling water blowdown from the process cooling system. A chromium-based corrosion inhibitor was used in the cooling water system. A chromium sludge was produced in a clarifier to control chromium levels in the water. Chromium sludge produced by this process was stored in two surface impoundments called the X-616 Chromium Sludge Lagoons. The sludge was toxic due to its chromium concentration and therefore required treatment. The sludge was treated, turning it into a sanitary waste, and buried in an Ohio EPA approved landfill. The plant's process cooling water system has changed to a more environmentally acceptable phosphate-based inhibitor. Closure activities at X-616 began in August 1990, with all construction activities completed in June 1991, at a total cost of $8.0 million

  17. Chromium oxidation state mapping in human cells

    Science.gov (United States)

    Ortega, R.; Fayard, B.; Salomé, M.; Devès, G.; Susini, J.

    2003-03-01

    The widespread use of chromium in industrial applications such as chemical production of pigments, refractory brick production, tanning, metallurgy, electroplating, and combustion of fuels has lead to human occupational exposure and to its increased introduction into the environment. Hexavalent chromium compounds are established carcinogens but their mechanism of cell transformation is not known. Up to now, no microanalytical technique was sensitive enough to allow the observation of chromium distribution, and oxidation state identification, within isolated cells at carcinogenic concentrations. In this experiment, we used successfully the ID-21 X-ray microscope to map Cr(VI) and total Cr distributions in cells exposed in vitro to soluble, and insoluble, Cr(VI) compounds. Exposure to soluble compounds, weak carcinogens, resulted in a homogeneous intracellular distribution of Cr, confirming by in situ measurement that Cr is present in the cell nucleus. Cr(VI) was never detected in cells which suggests a mechanism of rapid intracellular reducticn. On the other hand, exposure to insoluble compounds, strong carcinogens, also resulted in a homogeneous distribution of reduced forms of Cr in cells, and their nucleus. However, in this case, Cr(VI)-rich structures were observed into the cells suggesting that carcinogenicity is enhanced when oxidation reactions due to Cr(VI) chronic exposure are associated to Cr-DNA alterations.

  18. Dimensionally Controlled Lithiation of Chromium Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Fister, Tim T. [Argonne National Lab. (ANL), Argonne, IL (United States); Hu, Xianyi [Northwestern Univ., Evanston, IL (United States); Esbenshade, Jennifer [Univ. of Illinois, Urbana-Champaign, IL (United States); Chen, Xiao [Northwestern Univ., Evanston, IL (United States); Wu, Jinsong [Northwestern Univ., Evanston, IL (United States); Dravid, Vinayak [Northwestern Univ., Evanston, IL (United States); Bedzyk, Michael [Northwestern Univ., Evanston, IL (United States); Long, Brandon [Argonne National Lab. (ANL), Argonne, IL (United States); Gewirth, Andrew A. [Univ. of Illinois, Urbana-Champaign, IL (United States); Shi, Bing [Argonne National Lab. (ANL), Argonne, IL (United States); Schlepütz, Christian M. [Argonne National Lab. (ANL), Argonne, IL (United States); Fenter, Paul [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-12

    Oxide conversion reactions are an alternative approach for high capacity lithium ion batteries but are known to suffer from structural irreversibility associated with the phase separation and reconstitution of reduced metal species and Li2O. In particular, the morphology of the reduced metal species is thought to play a critical role in the electrochemical properties of a conversion material. Here we use a model electrode with alternating layers of chromium and chromium oxide to better understand and control these phase changes in real-time and at molecular length scales. Despite lacking crystallinity at the atomic scale, this superstructure is observed (with X-ray reflectivity, XR) to lithiate and delithiate in a purely one-dimensional manner, preserving the layered structure. The XR data show that the metal layers act as nucleation sites for the reduction of chromium in the conversion reaction. Irreversibility during delithiation is due to the formation of a ternary phase, LiCrO2, which can be further delithiated at higher potentials. The results reveal that the combination of confining lithiation to nanoscale sheets of Li2O and the availability of reaction sites in the metal layers in the layered structure is a strategy for improving the reversibility and mass transport properties that can be used in a wide range of conversion materials.

  19. Chromium--a material for fusion technology

    International Nuclear Information System (INIS)

    Due to their low neutron-induced radioactivity chromium based materials are considered to be candidates for structure materials in fusion technology. In this paper investigations are presented of unirradiated chromium with a purity of 99.96% (DUCROPUR) and a dispersion strengthened chromium alloy Cr5Fe1Y2O3 (DUCROLLOY). Both materials have been produced in a powder metallurgical route. Mechanical tests of smooth and pre-cracked specimens have been performed in a wide temperature range. Below 280 deg. C the fracture toughness values of DUCROPUR are very low (1/2), above the transition temperature they exceed 500 MPa m1/2. Large plastic deformations have been observed. DUCROLLOY does not indicate such a significant increase of fracture toughness in the tested temperature range. But above 400 deg. C large plastic deformations can be obtained in bending samples, too. The fatigue crack propagation behaviour of DUCROPUR at 300 deg. C is similar to that of a ductile metal

  20. A REVIEW OF BIOSORPTION OF CHROMIUM IONS BY MICROORGANISMS

    OpenAIRE

    Inga Zinicovscaia

    2012-01-01

    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...

  1. CHROMIUM INDUCED CYTOTOXICITY IN BLACKGRAM (VIGNA MUNGO L.)

    OpenAIRE

    A. Chidambaram ، P. Sundaramoorthy ، A. Murugan ، K. Sankar Ganesh ، L. Baskaran

    2009-01-01

    Chromium is known to be highly toxic to biological systems. This study was designed to determine the mutagenic effects of different concentrations (0, 10, 25, 50, 100 and 200 mg/L) of hexavalent chromium on root tip cells of blackgram (Vigna mungo L. Hepper). The blackgram seeds were equi-spacially arranged in sterilized petriplates lined with filter paper and they were treated with different concentrations of chromium solution. In germination studies, the morphological growth parameters such...

  2. Processes affecting the remediation of chromium-contaminated sites.

    OpenAIRE

    Palmer, C.D.; Wittbrodt, P R

    1991-01-01

    The remediation of chromium-contaminated sites requires knowledge of the processes that control the migration and transformation of chromium. Advection, dispersion, and diffusion are physical processes affecting the rate at which contaminants can migrate in the subsurface. Heterogeneity is an important factor that affects the contribution of each of these mechanisms to the migration of chromium-laden waters. Redox reactions, chemical speciation, adsorption/desorption phenomena, and precipitat...

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

    International Nuclear Information System (INIS)

    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

  4. Production of a chromium Bose-Einstein condensate

    OpenAIRE

    Griesmaier, Axel; Stuhler, Jürgen; Pfau, Tilman

    2005-01-01

    The recent achievement of Bose-Einstein condensation of chromium atoms [1] has opened longed-for experimental access to a degenerate quantum gas with long-range and anisotropic interaction. Due to the large magnetic moment of chromium atoms of 6 {$\\mu$}B, in contrast to other Bose- Einstein condensates (BECs), magnetic dipole-dipole interaction plays an important role in a chromium BEC. Many new physical properties of degenerate gases arising from these magnetic forces have been predicted in ...

  5. Removal of chromium(VI) from saline wastewaters by

    OpenAIRE

    AKSU, Zümriye

    2002-01-01

    Some industrial wastewaters contain higher quantities of salts besides chromium(VI) ions so the effect of these salts on the biosorption of chromium(VI) should be investigated. The biosorption of chromium (VI) from saline solutions on two strains of living Dunaliella algae were tested under laboratory conditions as a function of pH, initial metal ion and salt (NaCl) concentrations in a batch system. The biosorption capacity of both Dunaliella strains strongly de...

  6. Increase of chromium utilization in stainless steel melting

    International Nuclear Information System (INIS)

    The processes of deoxidizing when melting stainless 18-10 steels in electric are furnaces by the method of remelting with wastes are investigated. The dependences of amount of reduced chromium on silicon consumption are made more precise. It is shown that it is useful to apply aluminium for deoxidation of acid high-chromium slags. Based on the data on pilot melts the extent to which aluminium can be used as a reducing agent for chromium is estimated. 3 refs., 2 figs

  7. Scientific Opinion on ChromoPrecise® cellular bound chromium yeast added for nutritional purposes as a source of chromium in food supplements and the bioavailability of chromium from this source

    OpenAIRE

    EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS)

    2012-01-01

    The Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re-evaluating the safety of ChromoPrecise® cellular bound chromium yeast added for nutritional purposes as a source of chromium in food supplements and the bioavailability of chromium from this source. ChromoPrecise® is a yeast preparation with an enriched trivalent chromium content, obtained by culture of Saccharomyces cerevisiae in the presence of chromium chloride. A daily intake of 100 µg ch...

  8. 10 CFR 1003.55 - OHA evaluation.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false OHA evaluation. 1003.55 Section 1003.55 Energy DEPARTMENT... Rescission § 1003.55 OHA evaluation. (a)(1) The OHA may initiate an investigation of any statement in an application and utilize in its evaluation any relevant facts obtained by such investigation. The OHA...

  9. 14 CFR 437.55 - Hazard analysis.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Hazard analysis. 437.55 Section 437.55... TRANSPORTATION LICENSING EXPERIMENTAL PERMITS Safety Requirements § 437.55 Hazard analysis. (a) A permittee must identify and characterize each of the hazards and assess the risk to public health and safety and...

  10. 39 CFR 3020.55 - Review.

    Science.gov (United States)

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Review. 3020.55 Section 3020.55 Postal Service... the Product Lists Described Within the Mail Classification Schedule § 3020.55 Review. The Commission shall review the request, the Postal Service reply, and any public comment to determine whether...

  11. 24 CFR 55.24 - Aggregation.

    Science.gov (United States)

    2010-04-01

    ... 24 CFR part 58), individual or aggregated approvals may be issued. A single compliance review and... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Aggregation. 55.24 Section 55.24... FLOODPLAIN MANAGEMENT Procedures for Making Determinations on Floodplain Management § 55.24...

  12. 49 CFR 192.55 - Steel pipe.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Steel pipe. 192.55 Section 192.55 Transportation... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Materials § 192.55 Steel pipe. (a) New steel pipe is... in accordance with paragraph (c) or (d) of this section. (b) Used steel pipe is qualified for...

  13. 36 CFR 5.5 - Commercial photography.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Commercial photography. 5.5 Section 5.5 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR COMMERCIAL AND PRIVATE OPERATIONS § 5.5 Commercial photography. (a) Motion pictures, television. Before any motion picture may be filmed or...

  14. 7 CFR 1700.55 - Telecommunications Program.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 11 2010-01-01 2010-01-01 false Telecommunications Program. 1700.55 Section 1700.55... AGRICULTURE GENERAL INFORMATION Loan and Grant Approval Authorities § 1700.55 Telecommunications Program. (a..., Telecommunications Program, has the authority to approve the following loans, loan guarantees, and...

  15. 10 CFR 55.73 - Criminal penalties.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Criminal penalties. 55.73 Section 55.73 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) OPERATORS' LICENSES Enforcement § 55.73 Criminal penalties. (a) Section 223 of the Atomic Energy Act of 1954, as amended, provides for criminal sanctions for willful...

  16. 40 CFR 96.55 - Banking.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Banking. 96.55 Section 96.55 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NOX BUDGET... Tracking System § 96.55 Banking. (a) NOX allowances may be banked for future use or transfer in...

  17. 28 CFR 345.55 - Longevity pay.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Longevity pay. 345.55 Section 345.55... (FPI) INMATE WORK PROGRAMS Inmate Pay and Benefits § 345.55 Longevity pay. (a) Except as provided in paragraph (b) of this section, an inmate earns longevity pay raises after 18 months spent in FPI work...

  18. 10 CFR 55.21 - Medical examination.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Medical examination. 55.21 Section 55.21 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) OPERATORS' LICENSES Medical Requirements § 55.21 Medical examination. An applicant for a license shall have a medical examination by a physician. A licensee shall have a...

  19. 10 CFR 30.55 - Tritium reports.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Tritium reports. 30.55 Section 30.55 Energy NUCLEAR..., Inspections, Tests, and Reports § 30.55 Tritium reports. (a)-(b) (c) Except as specified in paragraph (d) of this section, each licensee who is authorized to possess tritium shall report promptly to...

  20. 46 CFR 168.15-55 - Screening.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Screening. 168.15-55 Section 168.15-55 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS CIVILIAN NAUTICAL SCHOOL VESSELS Accommodations § 168.15-55 Screening. Provision must be made to protect the quarters against the admission...

  1. 10 CFR 61.55 - Waste classification.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Waste classification. 61.55 Section 61.55 Energy NUCLEAR... Requirements for Land Disposal Facilities § 61.55 Waste classification. (a) Classification of waste for near surface disposal—(1) Considerations. Determination of the classification of radioactive waste involves...

  2. 17 CFR 200.55 - Statutory obligations.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 2 2010-04-01 2010-04-01 false Statutory obligations. 200.55 Section 200.55 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION ORGANIZATION; CONDUCT AND ETHICS; AND INFORMATION AND REQUESTS Canons of Ethics § 200.55 Statutory obligations. In administering the law, members of this...

  3. 40 CFR 205.55 - Requirements.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Requirements. 205.55 Section 205.55 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks § 205.55 Requirements....

  4. 34 CFR 668.55 - Updating information.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 3 2010-07-01 2010-07-01 false Updating information. 668.55 Section 668.55 Education... Information § 668.55 Updating information. (a)(1) Unless the provisions of paragraph (a)(2) or (a)(3) of this... applicant to verify the information contained in his or her application for assistance in an award year...

  5. 7 CFR 52.55 - Political activity.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Political activity. 52.55 Section 52.55 Agriculture... Regulations Governing Inspection and Certification Miscellaneous § 52.55 Political activity. All inspectors..., to take an active part in political management or in political campaigns. Political activities...

  6. Chromium depletion from stainless steels during vacuum annealing

    International Nuclear Information System (INIS)

    The behaviour of chromium during selective evaporation by high temperature vacuum annealing has been investigated by means of energy dispersive X-ray analysis and by neutron activation analysis. It was established that the rate of chromium loss from austenitic stainless steels 316 and 321 is controlled by chromium inter-diffusion rather than tracer diffusion in the alloy. Two important parameters in selective removal of chromium from alloy steels are the variation in the chromium surface concentration with time and the depletion profile in the alloy. The present work gives support for the model in which loss of chromium is dependent on its diffusivity in the alloy and on an interface transfer coefficient. The results showed that the surface concentration of chromium decreased with increasing vacuum annealing time. The chromium depletion profile in the metal was in accord with the previous derived model, apart from an anomalous near surface region. Here the higher resolution of a neutron activation technique indicated a region within approximately 2 microns of the surface where the chromium concentration decreased more steeply than expected. (author)

  7. 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.

  8. Method of trivalent chromium concentration determination by atomic spectrometry

    Science.gov (United States)

    Reheulishvili, Aleksandre N.; Tsibakhashvili, Neli Ya.

    2006-12-12

    A method is disclosed for determining the concentration of trivalent chromium Cr(III) in a sample. The addition of perchloric acid has been found to increase the atomic chromium spectrometric signal due to Cr(III), while leaving the signal due to hexavalent chromium Cr(VI) unchanged. This enables determination of the Cr(III) concentration without pre-concentration or pre-separation from chromium of other valences. The Cr(III) concentration may be measured using atomic absorption spectrometry, atomic emission spectrometry or atomic fluorescence spectrometry.

  9. Tribological Characteristics of Chromium-active Carbon Electroplated Composite Coatings

    Institute of Scientific and Technical Information of China (English)

    GUKa-fi; HUAMeng; Yi-min

    2004-01-01

    A process of chromium electroplating using a standard bath with additives and active carbon particles was reported, and the tribological behaviors of the composite coatings using the pin-on-disk tester and the table wear tester were i nvestig(aed. Experimental results indicate that the electroplated chromium-active carbon composite coatings exhibited the low friction coefficient anti excellent anti-wear properties whets coffered with the normal chromium electroplated ones. The formation of active carbon particles within the chromium matrices can be explained by SEM analysis and the mechanis of wear resistance of the composite coatings were studied.

  10. Defect transformation in GSGG crystals during chromium ion activation

    International Nuclear Information System (INIS)

    Absorption and induced absorption spectra, dose dependence of induced absorption, thermoluminescence of GSGG crystals, nominally pure and activated with chromium and neodymium ions in different concentrations, are investigated. It is shown that it is chromium ion presence in large concentration that decreases the induced coloration in GSGG crystals after γ-irradiation at 300 K. Optimum concentration of chromium ions for the minimum of induced coloration are found. The mechanism of decrease of induced coloration consisting in Fermi level displacement by chromium ion activation is established. Defect concentration and localization and recombination possibilities of electrons and holes in GSGG crystals are estimated by computer simulation

  11. Oral bioavailability of chromium from a specific site.

    OpenAIRE

    Witmer, C M; Harris, R.; Shupack, S I

    1991-01-01

    Analysis of soil from a specific site in New Jersey indicated a low level of sodium and chromium present as a calcium compound. Chromium was then administered orally to young, mature male rats at a level of 240 micrograms/kg for 14 days as chromium-contaminated soil, as CaCrO4, and as an equimolar mixture of the soil and calcium salts for 14 days. The rats were sacrificed 24 hr after the last dosing, and tissues were taken immediately for chromium analysis. Blood, muscle, and liver contained ...

  12. MICRO-SEGREGATION OF CHROMIUM IN Fe-Cr ALLOY

    OpenAIRE

    Igata, N.; Sato, S; ANDO, T.; H. Doi; Nishikawa, O.; Shibata, M.

    1984-01-01

    The objective of this investigation is to clarify the behavior of chromium atoms in iron-5at.% chromium alloy. When the specimens were quenched after soultion annealing at 1150°C for 1hr, FIM image was only a bright area, but when they were tempered from 450°C to 650°C, both bright areas and dark areas were observed in the FIM image. In these quenched specimens there was microsegregation of chromium atoms : In bright areas the chromium concentration was lower, and in dark areas it was higher ...

  13. Influence of Chelating Agents on Chromium Fate in Sediment

    Institute of Scientific and Technical Information of China (English)

    WANGXIAOCHANG; SUNJINHE; 等

    1996-01-01

    A laboratory investigation on reaction between chelating agents and chromium was conducted to evaluate the effect of chelating agents on the adsorption and desorption of chromium in sediment.The amount of adsorbed chromium(VI) in sediment decreased slightly by 5%-10% because of addition of chelating agents.Chelating agents inhibited the removal of Cr(Ⅲ)by sediment from solutions and the inhibiting effect was in the order:citric acid>tartaric acid>EDTA,Salicylic acid.No effect of chelating agents on desorption of chromium in sediment was observed.

  14. Analysing the chromium-chromium multiple bond using multiconfigurational quantum chemistry

    OpenAIRE

    Brynda, Marcin; Gagliardi, Laura; Roos, Björn O.

    2009-01-01

    This Letter discusses the nature of the chemical bond between two chromium atoms in different di-chromium complexes with the metal atoms in different oxidation states. Starting with the Cr diatom, with its formally sextuple bond and oxidation number zero, we proceed to analyse the bonding in some Cr(I)–Cr(I) XCrCrX complexes with X varying from F, to Phenyl, and Aryl. The bond distance in these complexes varies over a large range: 1.65–1.83 Å and we suggest explanations for these variations. ...

  15. The effect of chromium picolinate on serum cholesterol and apolipoprotein fractions in human subjects.

    OpenAIRE

    Press, R. I.; Geller, J.; Evans, G. W.

    1990-01-01

    Chromium has been implicated as a cofactor in the maintenance of normal lipid and carbohydrate metabolism. A deficiency of chromium results from diets low in biologically available chromium. Picolinic acid, a metabolite of tryptophan, forms stable complexes with transitional metal ions, which results in an improved bioavailability of the metal ion chromium. To determine whether or not chromium picolinate is effective in humans, 28 volunteer subjects were given either chromium tripicolinate (3...

  16. The Effect of Chromium Added into Basal Diet on Serum Total Protein, Urea, Triglyceride, Cholesterol and Serum and Tissue Chromium, Zinc, Copper Levels in Rabbits

    OpenAIRE

    *, Kâzim ŞAHİN; *, Talat GÜLER; +, N. ŞAHİN; *, O. N. ERTAS; +, N. ERKAL

    1999-01-01

    This study was conducted to determine the effect of supplemantal dietary chromium on serum total protein, urea, triglycerides, cholesterol, and serum and tissue chromium, zinc, and copper contents of pregnant rabbits, their offspring and their young rabbits. Treatment groups consisted of chromium level as follows: Control Group no supplementation chromium into basal diet, Treatment I (200 ppb Group) contained 200 ppb of supplemental chromium into basal diet, and Treatment II (400 ppb Group...

  17. STABILITY AND ABSORPTION OF CHROMIUM AND ABSORPTION OF CHROMIUM HISTIDINE BY HUMANS

    Science.gov (United States)

    Increased intake of chromium has been shown to lead to improvements in glucose, insulin, lipids, and related variables in studies involving humans, experimental and farm animals. However, the results are often variable depending not only upon the selection of subjects, but also dietary conditions a...

  18. Chromium and Polyphenols From Cinnamon Improve Insulin Sensitivity

    Science.gov (United States)

    Naturally occurring compounds that have been shown to improve insulin sensitivity include chromium and polyphenols found in cinnamon. These compounds also have similar effects on insulin signaling and glucose control. The signs of chromium deficiency are similar to those for the metabolic syndrome ...

  19. IRIS Toxicological Review of Hexavalent Chromium (2010 External Review Draft)

    Science.gov (United States)

    [UPDATE] New Schedule for IRIS Hexavalent Chromium Assessment In Feb 2012, EPA developed a new schedule for completing the IRIS hexavalent chromium assessment. Based on the recommendations of the external peer review panel, which met in May 2011 to review the dra...

  20. Composition and structure of plasma sprayed chromium steel powders

    Czech Academy of Sciences Publication Activity Database

    Schneeweiss, O.; Voleník, Karel; Kolman, Blahoslav Jan

    Praha, 2005, s. 105-111. ISBN 1899072 18 7. [EURO Powder Metallurgy Congress & Exhibition. Prague (CZ), 02.10.2005-05.10.2005] Institutional research plan: CEZ:AV0Z20430508 Keywords : chromium steel * plasma spraying * chromium depletion * Mössbauer spectroscopy Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  1. Safety, absorption, and antioxidant effects of chromium histidine

    Science.gov (United States)

    Supplemental chromium has been shown to be involved in the alleviation of the metabolic syndrome, glucose intolerance, polycystic ovary syndrome, depression, excess body fat, and gestational, steroid-induced, and type 2 diabetes. Chromium amino acid complexes that contained histidine displayed cons...

  2. Toxicity and adaptation of Dictyosphaerium chlorelloides to extreme chromium contamination.

    Science.gov (United States)

    Sánchez-Fortún, Sebastián; López-Rodas, Victoria; Navarro, Macarena; Marvá, Fernando; D'ors, Ana; Rouco, Mónica; Haigh-Florez, David; Costas, Eduardo

    2009-09-01

    Metals are often spilled by industries into inland water environments, with adverse consequences. Numerous papers have reported that heavy metals produce massive destruction of algae. Nevertheless, algal populations seem to become tolerant when they have had previous exposures to heavy metals. Because the mechanisms allowing heavy metal tolerance of algae are not yet known, the present study analyzed the effect of hexavalent chromium on growth and photosynthetic performance of Dictyosphaerium chlorelloides, stressing on the adaptation mechanisms to chromium contamination. Growth and photosynthetic performance of algal cells were inhibited by Cr(VI) at 10 mg/L, and the 72-h median inhibition concentration was established as 1.64 and 1.54 mg/L, respectively. However, after further incubation for a three month period in an environment with 25 mg/L of chromium, some rare, chromium-resistant cells occasionally were found. A Luria-Delbrück fluctuation analysis was performed to distinguish between resistant algae arising from rare, spontaneous mutations and resistant algae arising from physiological adaptation and other adaptive mechanisms. Resistant cells arose only by spontaneous mutations before the addition of chromium, with a rate of 1.77 x 10(-6) mutants per cell division. From a practical point of view, the use of both chromium-sensitive and chromium-resistant genotypes could make possible a specific algal biosensor for chromium. PMID:19323601

  3. Residual Chromium in Leather by Instrumental Neutron Activation Analysis

    Directory of Open Access Journals (Sweden)

    S. Okoh

    2012-01-01

    Full Text Available Problem statement: Most tanning processes employ the use of chromium sulphate. For chromium tanned leather, finished products may contain high amount of residual chromium. This may pose some health hazards, since chromium is known to be toxic at elevated concentration. This justifies the need for the study. Approach: Various samples of leather were collected from a tannery, a leather crafts market, a leather dump site and from local tanners all in Kano, Nigeria in 2009. The samples were irradiated for 6 h in the inner site of the Nigerian Research Reactor (NIRR-1 at a flux of 5×1011 ncm-2 sec-1. Results: After evaluating the spectrum, the mean results for chromium in the samples were determined as 2.33±0.3, 2.23±0.3 and 2.93±0.4% for samples from the tannery, leather crafts market and leather dump sites respectively. Chromium concentration in samples collected from local tanners who use tannins from Acacia nilotica as tanning agent was below the detection limit of Instrumental Neutron Activation Analysis (INAA technique used in the study. Conclusion: Although, the concentrations of chromium in the analysed samples were not much higher than what were obtained in literature, they may be enough to sensitize the population that is allergic to chromium.

  4. AMORPHOUS ALLOY SURFACE COATINGS FOR HARD CHROMIUM REPLACEMENT - PHASE I

    Science.gov (United States)

    Hard chromium coatings (0.25 to10 mil thick) are used extensively for imparting wear and erosion resistance to components in both industrial and military applications. The most common means of depositing hard chromium has been through the use of chromic acid baths containing ...

  5. ADVANCES IN HEXAVALENT CHROMIUM REMOVAL AT HANFORD

    Energy Technology Data Exchange (ETDEWEB)

    NESHEM DO; RIDDELLE J

    2012-01-30

    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

  6. 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.

  7. 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...... the calculated ground state properties into agreement with experiment. The magnetisation is studied as function of volume in several models, and it is shown that a Stoner picture provides an extremely accurate description of the full calculation provided the sp-d hybridisation is taken into account. It is found...

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

    International Nuclear Information System (INIS)

    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

  9. 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.

  10. Biosorption potency of Aspergillus niger for removal of chromium (VI).

    Science.gov (United States)

    Srivastava, Shaili; Thakur, Indu Shekhar

    2006-09-01

    Aspergillus niger isolated from soil and effluent of leather tanning mills had higher activity to remove chromium. The potency of Aspergillus niger was evaluated in shake flask culture by absorption of chromium at pH 6 and temperature 30 degrees C. The results of the study indicated removal of more than 75% chromium by Aspergillus niger determined by diphenylcarbazide colorimetric assay and atomic absorption spectrophotometry after 7 days. Study of microbial Cr(VI) reduction and identification of reduction intermediates has been hindered by the lack of analytical techniques that can identify the oxidation state with subcellular spatial resolution. Therefore, removal of chromium was further substantiated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), which indicated an accumulation of chromium in the fungal mycelium. PMID:16874547

  11. 15 CFR 5.5 - Vending machines.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Vending machines. 5.5 Section 5.5 Commerce and Foreign Trade Office of the Secretary of Commerce OPERATION OF VENDING STANDS § 5.5 Vending machines. (a) The income from any vending machines which are located within reasonable proximity to and are in direct competition with a...

  12. Selenium protection from cadmium and chromium poisoning

    International Nuclear Information System (INIS)

    The interaction of selenium with cadmium and chromium was studied in 168 chicken-broilers (DWCxWR) divided into four equal groups. Eight-week old control animals received an intravenous dose of /sup 115m/Cd Chloride 370 KBq/Kg (Group I), or 51Cr Chloride 370 KBq/Kg (Group II). The kinetics of these isotopes were studied by scintillation spectrometry (NaI/TI) carried out for whole blood, plasma, plasma proteins, urine, feces and homogenates of all organs at various time intervals. Animals in Groups III and IV received eight subcutaneous doses of sodium selenate (5ug) at 8-week intervals prior to /sup 115m/Cd or 51Cr. The kinetics of these elements were studied as in the previous two groups. It was found that selenium affected those kinetics in two ways: (a) by increasing the excretion of Cd by 11 +/- 3% (P < 0.001) and that of Cr by 7 +/- 1% (P < 0.001); and (b) by favoring redistribution of those elements, with significant (P < 0.001) reductions in liver, endocrine glands and kidney and increases (P < 0.01) in bone. The study suggests that selenium protects the animals' vital organs from environmental pollutants, such as cadmium and chromium

  13. The hydrogen anode in chromium electrowinning

    International Nuclear Information System (INIS)

    The use of a hydrogen anode for electrowinning of chromium from an ammonium chromium sulfate electrolyte (chrome alum process) was investigated in a laboratory-scale cell equipped with a diaphragm. The composition of the solution and the temperature followed industrial practice. Current density, pH, and anolyte flow rate through the diaphragm were varied and optimized for the cell. For a cathodic current density of 915 A/m2 at 50oC, the optimum initial pH was 2.37. The hydrogen anode was made of a platinized Toray carbon paper (0.35 mg Pt per cm2) supplied by E-TEK. The hydrogen pressure was maintained at 2 cm H20 above ambient atmosphere. The potential of the hydrogen anode was about 1 V lower than that of a Pb-Ag anode (1%Ag) in a similar cell. As expected, no Cr+6 was generated in the anolyte. The cathodic current efficiency was slightly lower with the hydrogen anode than with the Pb-Ag anode. (author)

  14. Biliary excretion of chromium in the rat

    International Nuclear Information System (INIS)

    The relative amount of chromium excreted in rat bile after injection of Cr-III is much less than after injection of Cr-VI, about 0.1% and from 6-8% during 5 hours respectively, for corresponding dose levels. The liver to bile ratio was 50-100 for Cr-III injection for Cr-VI the ratio was 2-3. With doses up to 18 μmol Cr/kg, only Cr-III was found in bile even after injection of CR-VI.Glutathione depletion of the liver with cyclohexene oxide decreased chromium excretion in bile. Such treatment also decresed the reduction of Cr-VI to Cr-III in the liver cell as only Cr-VI was found in bile. A different distribution of Cr-III in the liver dependent on whether derived from Cr-VI or taken up by the liver as such must be assumed. Taking into account the usual low penetration of biological membranes by Cr-III, a possible active transport mechanism or a specific diffusable Cr-III compound must be postulated. (author)

  15. 40 CFR 55.10 - Fees.

    Science.gov (United States)

    2010-07-01

    ... of 40 CFR part 71. (2) EPA will collect all other fees from OCS sources calculated in accordance with... from OCS sources in accordance with the requirements of 40 CFR part 71. ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Fees. 55.10 Section 55.10 Protection...

  16. 40 CFR 97.55 - Banking.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Banking. 97.55 Section 97.55 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) FEDERAL NOX... Banking. NOX allowances may be banked for future use or transfer in a compliance account, an...

  17. 34 CFR 5.5 - Records.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Records. 5.5 Section 5.5 Education Office of the Secretary, Department of Education AVAILABILITY OF INFORMATION TO THE PUBLIC PURSUANT TO PUB. L. 90-23 (Eff... pictures, or other documentary materials, regardless of physical form or characteristics, made or...

  18. 49 CFR 229.55 - Piston travel.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Piston travel. 229.55 Section 229.55... Piston travel. (a) Brake cylinder piston travel shall be sufficient to provide brake shoe clearance when... piston travel may not exceed 11/2 inches less than the total possible piston travel. The total...

  19. 40 CFR 142.55 - Final schedule.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Final schedule. 142.55 Section 142.55... schedule. (a) Within 30 days after the termination of the public hearing pursuant to § 142.54, the... schedule as necessary and prescribe the final schedule for compliance and interim measures for the...

  20. 41 CFR 105-55.002 - Definitions.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Definitions. 105-55.002 Section 105-55.002 Public Contracts and Property Management Federal Property Management Regulations System... corporations. (k) Hearing means a review of the documentary evidence concerning the existence and/or amount...

  1. 40 CFR 716.55 - Confidentiality claims.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Confidentiality claims. 716.55 Section 716.55 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL... for commercial distribution (including for test marketing purposes and for use in research...

  2. 27 CFR 7.55 - Comparative advertising.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Comparative advertising. 7.55 Section 7.55 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS LABELING AND ADVERTISING OF MALT BEVERAGES Advertising of Malt...

  3. Workshop on effects of chromium coating on Nb3Sn superconductor strand: Proceedings

    International Nuclear Information System (INIS)

    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 Nb3Sn strand

  4. Stabilization of chromium salt in ordinary portland cement

    Indian Academy of Sciences (India)

    Damir Barbir; Pero Dabić; Petar Krolo

    2012-12-01

    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. The microcalorimetrical results show that with increasing the share of chromium salt, heat maximums assume lower values and the occurrence of the maximum registered in the earlier hydration times. Conductometrical measurements show that with increasing addition of chromium salt, curve did not show any specific shape, immediate drop in specific conductivity is noticed and the maximum is reached earlier. This coincides with microcalorimetrical results. It can be concluded that the addition of chromium does not affect the mechanism of the hydration process, but it does affect the kinetic parameters and dynamics of the cement hydration process. It was found that chromium salt addition to the cement–water system is acceptable up to 2 wt.%. According to standard EN 196-3 for OPC, the beginning of binding time should occur after 60 minutes. Increased amount of chromium over 2 wt.% significantly accelerate the beginning of binding time and for the system it is not acceptable.

  5. Chromium speciation in rainwater: temporal variability and atmospheric deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kieber, R.J.; Willey, J.D.; Zvalaren, S.D. [University of North Carolina at Wilmington, Wilmington, NC (United States). Dept. of Chemistry

    2002-12-15

    Chromium is released into the atmosphere by a variety of anthropogenic activities which include steel manufacturing, leather tanning, wood presentation and fossil fuel combustion. The concentrations of the various chromium species were determined in 89 rainwater samples collected in Wilmington, NC from October 1, 1999 to December 31, 2001. Volume weighted annual average concentrations of Cr{sub total}, particulate Cr, Cr(III)(aq), and Cr(VI)(aq) were 4.6, 2.2, 0.8 and 1.2 nM, respectively. There was distinct seasonal and diurnal variability in the concentrations of the various chromium species. Chromium emissions to the global atmosphere by both natural and anthropogenic sources are estimated to be 2.2 x 10{sup 9} mol/yr. Using rainwater concentration data along with other published rainwater Cr concentrations and an estimate for total global annual rain, the total global flux of chromium removed from the atmosphere via wet deposition is 2.1 x 10{sup 9} mol/yr. This represents complete removal of Cr and indicates that essentially all chromium released into the global atmosphere is removed via rain. About half this chromium is dissolved with roughly equal concentrations of toxic Cr(VI) and relatively harmless Cr(III) species. 48 refs., 4 figs., 3 tabs.

  6. Bioavailability of a potato chromium complex to the laboratory rat

    International Nuclear Information System (INIS)

    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

  7. Chromium-induced membrane damage: protective role of ascorbic acid

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Importance of chromium as environmental toxicant is largely due to impact on the body to produce cellular toxicity. The impact of chromium and their supplementation with ascorbic acid was studied on plasma membrane of liver and kidney in male Wistar rats (80 - 100gbody weight). It has been observed that the intoxication with chromium ( i. p. ) at the dose of 0.8 mg/100g body weight per day for a period of 28 days causes significant increase in the level of cholesterol and decrease in the level of phospbolipid of both liver and kidney. The alkaline pbosphatase, total ATPase and Na + -K + -ATPase activities were significantly decreased in both liver and kidney after chromium treatment,except total ATPase activity of kidney. It is suggested that chromium exposure at the present dose and duration induce for the alterations of structure and function of both liver and kidney plasma membrane. Ascorbic acid ( i.p. at the dose of 0.5 mg,/100g body weight per day for period of 28 days) supplementation can reduce these structural changes in the plasma membrane of liver and kidney. But the functional changes can not be completely replenished by the ascorbic acid supplementation in response to chromium exposure. So it is also suggested that ascorbic acid (nutritional antioxidant) is useful free radical scavenger to restrain the chromium-induced membrane damage.

  8. Speciation of chromium using chronoamperometric biosensors based on screen-printed electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Calvo-Pérez, Ana, E-mail: anacp@ubu.es; Domínguez-Renedo, Olga, E-mail: olgado@ubu.es; Alonso-Lomillo, MAsunción, E-mail: malomillo@ubu.es; Arcos-Martínez, MJulia, E-mail: jarcos@ubu.es

    2014-06-23

    Highlights: • Chronoamperometric determination of Cr(III) on tyrosinase based biosensors using SPCEs. • Chronoamperometric determination of Cr(VI) on GOx based biosensors using SPCEs. • High degree of sensitivity and selectivity in the analysis of both chromium species. • Bipotentiostatic chronoamperometric determination of both chromium species in the same sample. - Abstract: Chronoamperometric assays based on tyrosinase and glucose oxidase (GOx) inactivation have been developed for the monitoring of Cr(III) and Cr(VI). Tyrosinase was immobilized by crosslinking on screen-printed carbon electrodes (SPCEs) containing tetrathiafulvalene (TTF) as electron transfer mediator. The tyrosinase/SPC{sub TTF}E response to pyrocatechol is inhibited by Cr(III). This process, that is not affected by Cr(VI), allows the determination of Cr(III) with a capability of detection of 2.0 ± 0.2 μM and a reproducibility of 5.5%. GOx modified screen-printed carbon platinised electrodes (SPC{sub Pt}Es) were developed for the selective determination of Cr(VI) using ferricyanide as redox mediator. The biosensor was able to discriminate two different oxidation states of chromium being able to reject Cr(III) and to detect the toxic species Cr(VI). Chronoamperometric response of the biosensor towards glucose decreases with the presence of Cr(VI), with a capability of detection of 90.5 ± 7.6 nM and a reproducibility of 6.2%. A bipotentiostatic chronoamperometric biosensor was finally developed using a tyrosinase/SPC{sub TTF}E and a GOx/SPC{sub Pt}E connected in array mode for the simultaneous determination of Cr(III) and Cr(VI) in spiked tap water and in waste water from a tannery factory samples.

  9. Speciation of chromium using chronoamperometric biosensors based on screen-printed electrodes

    International Nuclear Information System (INIS)

    Highlights: • Chronoamperometric determination of Cr(III) on tyrosinase based biosensors using SPCEs. • Chronoamperometric determination of Cr(VI) on GOx based biosensors using SPCEs. • High degree of sensitivity and selectivity in the analysis of both chromium species. • Bipotentiostatic chronoamperometric determination of both chromium species in the same sample. - Abstract: Chronoamperometric assays based on tyrosinase and glucose oxidase (GOx) inactivation have been developed for the monitoring of Cr(III) and Cr(VI). Tyrosinase was immobilized by crosslinking on screen-printed carbon electrodes (SPCEs) containing tetrathiafulvalene (TTF) as electron transfer mediator. The tyrosinase/SPCTTFE response to pyrocatechol is inhibited by Cr(III). This process, that is not affected by Cr(VI), allows the determination of Cr(III) with a capability of detection of 2.0 ± 0.2 μM and a reproducibility of 5.5%. GOx modified screen-printed carbon platinised electrodes (SPCPtEs) were developed for the selective determination of Cr(VI) using ferricyanide as redox mediator. The biosensor was able to discriminate two different oxidation states of chromium being able to reject Cr(III) and to detect the toxic species Cr(VI). Chronoamperometric response of the biosensor towards glucose decreases with the presence of Cr(VI), with a capability of detection of 90.5 ± 7.6 nM and a reproducibility of 6.2%. A bipotentiostatic chronoamperometric biosensor was finally developed using a tyrosinase/SPCTTFE and a GOx/SPCPtE connected in array mode for the simultaneous determination of Cr(III) and Cr(VI) in spiked tap water and in waste water from a tannery factory samples

  10. REDUKSI LOGAM BERAT CHROMIUM (VI DENGAN FOTOKATALIS KOMPOSIT TiO2-SiO2

    Directory of Open Access Journals (Sweden)

    Candra Purnawan

    2013-10-01

    Full Text Available AbstractsComposite TiO2-SiO2 has been synthesized using sol-gel process with starting materialsTiCl4 and Na2SiO3. The purposes of this research were to know the effect of compositecomposition, pH solution and UV radiation time for reduced Chromium (VI cations. Theidentification and characterization of composite were done by infrared spectroscopy (IRand X-Ray Diffraction. Condition of Chromium (VI reduction by composite TiO2-SiO2 werecarried out with variation of composite TiO2-SiO2 concentration or the ratio Ti:Si were1:0,1 ; 1:0,5 ; 1:1 ; 1:1,5 ; 1:2. Variation of pH solution in 3,0; 3,5; 4,0; 4,5; 5,0; 5,5; 6,0; 6,5;7,0 and variation of UV radiation times in 2, 4, 6, 12, 18, 24, 30, 36, 42, 48 hours.The result showed that XRD characteristic of TiO2-SiO2 composite showed 2q peaks at 22.94degrees and 36.24 degrees. IR characteristic of TiO2-SiO2 showed absorption of Ti-O-Si inthe wave number 962 cm-1. The optimum reduction of Chromium (VI cations using TiO2-SiO2 composite in Ti:Si = 1:1 composition, pH 3 and with 18 hours radiation times.

  11. Fertilizers and Mixed Crop Cultivation of Chromium Tolerant and Sensitive Plants under Chromium Toxicity

    OpenAIRE

    B. Dheeba; Sampathkumar, P; Kannan, K.

    2015-01-01

    Zea mays (maize) and Vigna radiata (green gram) are found to be the chromium (Cr) tolerant and sensitive plants, respectively. In the present paper, we investigate the reduction of the toxicity of Cr in the sensitive plants by the mixed crop cultivation in the field using various amendments. Further, the potassium dichromate was used as the source of hexavalent Cr. The results indicated that Cr adversely affects both the growth and yield of plants. The soil properties vary with Cr and differe...

  12. Microbial Diversity of Chromium-Contaminated Soils and Characterization of Six Chromium-Removing Bacteria

    Science.gov (United States)

    He, Zhiguo; Hu, Yuting; Yin, Zhen; Hu, Yuehua; Zhong, Hui

    2016-06-01

    Three soil samples obtained from different sites adjacent to a chromium slag heap in a steel alloy factory were taken to examine the effect of chromium contamination on soil bacterial diversity as determined by construction of 16S rDNA clone libraries and sequencing of selected clones based on restriction fragment length polymorphism (RFLP) analysis. Results revealed that Betaproteobacteria, Gammaproteobacteria, Firmicutes, and Alphaproteobacteria occurred in all three soil samples, although the three samples differed in their total diversity. Sample 1 had the highest microbial diversity covering 12 different classes, while Sample 3 had the lowest microbial diversity. Strains of six different species were successfully isolated, one of which was identified as Zobellella denitrificans. To our knowledge, this is the first report of a strain belonging to the genus Zobellella able to resist and reduce chromium. Among all isolates studied, Bacillus odysseyi YH2 exhibited the highest Cr(VI)-reducing capability, with a total removal of 23.5 % of an initial Cr(VI) concentration of 350 mg L-1.

  13. Chromium removal from tannery wastewater by using of flying ash

    International Nuclear Information System (INIS)

    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

  14. 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

  15. Thermal incorporation behavior during the reduction and stabilization of chromium wastes

    OpenAIRE

    Yang, Jun; 楊駿

    2015-01-01

    The possibility of employing periclase to stabilize chromium in chromium wastes into spinel-based ceramics through thermal method was investigated by heating mixture of simulated chromium waste and magnesium oxide. Different types of magnesium oxide precursors were introduced to incorporate chromium oxide into magnesiochromite (MgCr2O4) ranging from 550 ºC to 1350 ºC. Magnesium oxide precursors of both types can effectively incorporate chromium oxide but via different mechanisms. Three main f...

  16. Effects of Supplemental Dietary Chromium on Yield and Nutrient Digestibility of Laying Hens Under Low Temperature

    OpenAIRE

    ŞAHİN, Kazım; ERTAŞ, O. Nihat; GÜLER, Talat; ÇİFTÇİ, Mehmet

    2001-01-01

    This study was conducted to determine the effects of chromium picolinate (CrPi) added into diet containing 710.3 ppb chromium on yield and nutrient digestibility of laying hens at low temperature. Forty-six-week-old laying hens were randomly assigned to four groups of 30 hens per group. Treatment groups were fed different supplemental dietary chromium levels. Thus, hens were fed diets with no supplemental chromium (Control Group), 100 ppb of supplemental chromium (100 Group), 200 ppb of s...

  17. Evaluation of the comprehensiveness and reliability of the chromium composition of foods in the literature ☆

    OpenAIRE

    Thor, Mayly Y.; Harnack, Lisa; King, Denise; Jasthi, Bhaskarani; Pettit, Janet

    2011-01-01

    In the early 1960s, trivalent chromium Cr3+ became recognized as an essential trace element due to its potential metabolic and cardiovascular benefits. No comprehensive chromium database currently exists; thus a thorough review of the literature was conducted to examine the availability and reliability of chromium data for foods. A number of key issues were identified that challenge the feasibility of adding chromium to a food and nutrient database. Foremost, dietary chromium data reported in...

  18. Chromium(III) complexation to natural organic matter : Mechanisms and modeling

    OpenAIRE

    Gustafsson, Jon Petter; Persson, I.; Oromieh, A. G.; Van Schaik, J. W. J.; Sjöstedt, Carin; Kleja, D. B.

    2014-01-01

    Chromium is a common soil contaminant, and it often exists as chromium(III). However, limited information exists on the coordination chemistry and stability of chromium(III) complexes with natural organic matter (NOM). Here, the complexation of chromium(III) to mor layer material and to Suwannee River Fulvic Acid (SRFA) was investigated using EXAFS spectroscopy and batch experiments. The EXAFS results showed a predominance of monomeric chromium(III)-NOM complexes at low pH (<5), in which o...

  19. Abatement of Chromium Emissions from Steelmaking Slags - Cr Stabilization by Phase Separation

    OpenAIRE

    Albertsson, Galina

    2013-01-01

    Chromium is an important alloying element in stainless steel but also environmentally harmful element. A number of mineralogical phases present in the slag matrix can contain chromium and lead to chromium leaching. Chromium in slag if not stabilized, could oxidize to the cancerogenic hexavalent state, and leach out if exposed to acidic and oxygen rich environment. Other environmental concerns are slag dusting and chromium escape to the atmosphere. Despite the fact that there is a certain risk...

  20. The oxidation and reduction of chromium of stainless steels in an eletric arc furnace

    OpenAIRE

    Arh, B.; F. Tehovnik

    2011-01-01

    The oxidation of chromium during the elaboration of stainless steels occurs with oxygen in solution blown inthe melt and with oxides in the slag. A higher content of silicon in the furnace charge decreases the extent of oxidation of chromium, however, the efficient reduction of chromium from the slag is of essential importance for a minimal loss of chromium. In this survey, the theory of the oxidation of chromium, its reduction from the slag and the conditions for the formation of foaming sla...

  1. Chromium accumulation, microorganism population and enzyme activities in soils around chromium-containing slag heap of steel alloy factory

    Institute of Scientific and Technical Information of China (English)

    HUANG Shun-hong; PENG Bing; YANG Zhi-hui; CHAI Li-yuan; ZHOU Li-cheng

    2009-01-01

    The environmental risk of chromium pollution is pronounced in soils adjacent to chromate industry. It is important to investigate the functioning of soil microorganisms in ecosystems exposed to long-term contamination by chromium. 45 soil samples obtained from different places of the slag heap in a steel alloy factory were analyzed for chromium contamination level and its effect on soil microorganisms and enzyme activities. The results show that the average concentrations of total Cr in the soil under the slag heap, adjacent to the slag heap and outside the factory exceed the threshold of Secondary Environmental Quality Standard for Soil in China by 354%, 540% and 184%, respectively, and are 15, 21 and 9 times higher than the local background value, respectively. Elevated chromium loadings result in changes in the activity of the soil microbe, as indicated by the negative correlations between soil microbial population and chromium contents. Dehydrogenase activity is greatly depressed by chromium in the soil. The results imply that dehydrogenase activity can be used as an indicator for the chromium pollution level in the area of the steel alloy factory.

  2. Evaluation of chromium in red blood cells as an indicator of exposure to hexavalent chromium: An in vitro study.

    Science.gov (United States)

    Devoy, Jérôme; Géhin, Antoine; Müller, Samuel; Melczer, Mathieu; Remy, Aurélie; Antoine, Guillaume; Sponne, Isabelle

    2016-07-25

    Chromium(VI) compounds are classified as carcinogenic to humans. Whereas chromium measurements in urine and whole blood (i.e., including plasma) are indicative of recent exposure, chromium in red blood cells (RBC) is attributable specifically to Cr(VI) exposure. Before recommending Cr in RBC as a biological indicator of Cr(VI) exposure, in-vitro studies must be undertaken to assess its reliability. The present study examines the relationship between the chromium added to a blood sample and that subsequently found in the RBC. After incubation of total blood with chromium, RBC were isolated, counted and their viability assessed. Direct analysis of chromium in RBC was conducted using Atomic Absorption Spectrometry. Hexavalent, but not trivalent Cr, was seen to accumulate in the RBC and we found a strong correlation between the Cr(VI) concentration added to a blood sample and the amount of Cr in RBC. This relationship appears to be independent of the chemical properties of the human blood samples (e.g., different blood donors or different reducing capacities). Even though in-vivo studies are still needed to integrate our understanding of Cr(VI) toxicokinetics, our findings reinforce the idea that a single determination of the chromium concentration in RBC would enable biomonitoring of critical cases of Cr(VI) exposure. PMID:27178267

  3. 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...... weathering profile. The negatively fractionated δ53Cr values measured in the weathering profile relative to the unaltered tonalitic bedrock characterized by a high temperature magmatic inventory Cr isotope signature are consistent with loss of a positively fractionated Cr(VI) pool formed during weathering...... highly oxidative conditions, which in well drained sulfide-bearing parent bedrocks potentially lead to both, acid dissolution of sulfide-hosted Cr and redox-promoted mobilization of Cr(VI) from silicates during later stages of weathering under basic pH conditions....

  4. Neutron capture by the chromium isotopes

    International Nuclear Information System (INIS)

    Capture cross sections of the chromium isotopes have been measured at neutron energies up to 350 keV using the capture cross section facility at the 40 m station of the Oak Ridge Electron Linear Accelerator. Parameters have been derived for 180 resonances. A moderate correlation [rho(gamma-n-0,gamma-gamma) approximately 0.45] is observed between reduced neutron widths and radiative widths for s-wave resonances. Calculations of valence widths show that valence capture can only account for the correlated component of the observed radiative widths. An additional mechanism such as a 2p-1h doorway state must therefore be occurring to explain the uncorrelated component. (author)

  5. Biosorption of chromium(VI) ion from aqueous solutions using walnut, hazelnut and almond shell.

    Science.gov (United States)

    Pehlivan, Erol; Altun, Türkan

    2008-06-30

    The potential to remove Cr(VI) ion from aqueous solutions through biosorption using, the shells of Walnut (WNS) (Juglans regia), Hazelnut (HNS) (Corylus avellana) and Almond (AS) (Prunus dulcis) was investigated in batch experiments. The equilibrium adsorption level was determined to be a function of the solution contact time and concentration. Kinetic experiments revealed that the dilute chromium solutions reached equilibrium within 100 min. The biosorptive capacity of the shells was dependent on the pH of the chromium solution, with pH 3.5 being optimal. Adsorption of Cr(VI) ion uptake is in all cases pH-dependent showing a maximum at equilibrium pH values between 2.0 and 3.5, depending on the biomaterial, that correspond to equilibrium pH values of 3.5 for (WNS), 3.5 for (HNS) and 3.2 for (AS). The adsorption data fit well with the Langmuir isotherm model. The sorption process conformed to the Langmuir isotherm with maximum Cr(VI) ion sorption capacities of 8.01, 8.28, and 3.40 mg/g for WNS, HNS and AS, respectively. Percentage removal by WNS, HNS and AS was 85.32, 88.46 and 55.00%, respectively at a concentration of 0.5 mM. HNS presented the highest adsorption capacities for the Cr(VI) ion. PMID:18179865

  6. The toxic effects on the stress and immune responses in juvenile rockfish, Sebastes schlegelii exposed to hexavalent chromium.

    Science.gov (United States)

    Kim, Jun-Hwan; Kang, Ju-Chan

    2016-04-01

    Juvenile Sebastes schlegelii (mean length 13.7±1.7cm, and mean weight 55.6±4.8g) were exposed for 4 weeks with the different levels of dietary chromium (Cr(6+)) concentration (0, 30, 60, 120 and 200mg/L). The plasma cortisol and heat shock protein 70 was evaluated as stress indicators. Plasma cortisol was significantly increased in response to the dietary chromium exposure over 120mg/kg at 2 and 4 weeks. Heat shock protein 70 was also notably increased over 120mg/kg at 2 weeks and over 60mg/kg at 4 weeks. In the immune response, immunoglobulin M was considerably increased in the concentration of 240mg/kg at 2 weeks and over 120mg/kg at 4 weeks. Lysozyme activity was considerably induced by the dietary hexavalent chromium exposure. A significant increase in plasma lysozyme activity was observed at 240mg/kg after 2 weeks and over 60mg/kg after 4 weeks, kidney lysozyme was also increased over 120mg/kg at 2 and 4 weeks. The results demonstrate that dietary Cr exposure can induce a significant stress and immune stimulation. PMID:26991846

  7. Chromium and Polyphenols from Cinnamon and Insulin Sensitivity

    Science.gov (United States)

    Factors that improve insulin sensitivity usually lead to improvements in risk factors associated with the metabolic syndrome, diabetes, and cardiovascular diseases. Naturally occurring bioactive compounds that have been shown to improve insulin sensitivity include chromium and polyphenols found in ...

  8. Contingency plans for chromium utilization. Publication NMAB-335

    International Nuclear Information System (INIS)

    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

  9. Synthesis and characterization of novel chromium pillared clays

    International Nuclear Information System (INIS)

    New chromium pillared clays of basal spacing 2.45 nm were synthesized and characterized. The chromium oligomers used for intercalation were prepared by quick addition of base and acid to Cr(III) monomeric solutions followed by reflux. The synthesized clays exhibit increased BET surface area and higher micropore volume compared to clays with lower galleries, pillared either by smaller Cr(III) oligomers or by Cr(III) monomers. Important parameters affecting the d001 basal spacing were studied, e.g. the pH of the pillaring solution, the intercalation time, the chromium concentration and the counter-anion present in the chromium solutions. Scanning electron micrographs were acquired to demonstrate changes of the clay texture before and after pillaring. The thermal behavior of the synthesized clays was also examined

  10. Adsorption Properties of Chromium (VI by Chitosan Coated Montmorillonite

    Directory of Open Access Journals (Sweden)

    Dahe Fan

    2006-01-01

    Full Text Available The adsorption of chromium (VI by Chitosan Coated Montmorillonite (CCM from aqueous solution was studied. To evaluate the adsorption capacity, the effects of pH, initial concentration and temperature on the adsorption were investigated. The isothermal data was applied to Langmuir linear and the Freundlich linear isotherm equation and the thermodynamic parameters (ΔH, ΔG, ΔS were calculated according to the values of binding Langmuir constant, KL. Results indicated that the adsorption between CCM and chromium (VI was significantly physical, the negative ΔH constant at lower temperature confirmed that the more chromium (VI was adsorbed by chitosan coated montmorillonite at lower temperature. The kinetics of the sorption process of chromium (VI on chitosan coated montmorillonite were investigated using the pseudo-first order and pseudo-second order kinetics, results showed that the pseudo-second order equation model provided the best correlation with the experimental results.

  11. 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.

  12. Fabrication of high rate chromium getter sources for fusion applications

    International Nuclear Information System (INIS)

    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

  13. Detecting Grain-Boundary Chromium Depletion in Inconel 600

    Science.gov (United States)

    Airey, G. P.; Vaia, A. R.; Pessall, N.; Aspden, R. G.

    1981-11-01

    Techniques to evaluate grain-boundary chromium depletion in Inconel Alloy 600 were investigated. Procedures studied were a modified Huey test, reactivation polarization, magnetic permeability measurements, and eddy current measurements. Results from these tests were correlated with susceptibility to stress-assisted intergranular cracking in polythionic acid. Thermally treated Inconel Alloy 600 steam generator tubing was the principal source of material evaluated, but experimental heats of Ni-Cr-Fe alloys with 8-18 wt.% Cr were prepared to determine the critical chromium level below which stress-assisted intergranular cracking occurs; this critical chromium content was found to be between 9.8 and 11.7 wt.%. All four techniques were considered suitable to evaluate grain-boundary chromium depletion; the modified Huey test and reactivation polarization technique showed a greater sensitivity than the magnetic permeability and eddy current measurements.

  14. The diffusion of chromium in a duplex alloy steel

    International Nuclear Information System (INIS)

    Diffusion of chromium in a duplex stainless steel containing approximately 8% ferrite has been investigated in the temperature range 600 to 10000C using the standard serial sectioning technique. The resulting concentration profiles exhibited up to four distinct regions. The two main regions are attributed to volume diffusion in the austenite and ferrite phases, the other zones being due to short circuiting paths. Volume diffusion in the austenite phase is in good agreement with chromium diffusion in Type 316 steel. The chromium diffusion coefficient in the ferrite phase of approximate composition 25 wt % Cr, 5 wt % Ni is given by: Dsub(α) = (6.0(+11,-3)) x 10-6 exp - ((212+-5)/RT) m2s-1 the activation energy being expressed in kJ.mol-1. Little evidence was found for enhanced chromium diffusion along austenite/ferrite interface boundaries. (author)

  15. Chromium plating pollution source reduction by plasma source ion implantation

    International Nuclear Information System (INIS)

    There is growing concern over the environmental toxicity and workers' health issues due to the chemical baths and rinse water used in the hard chromium plating process. In this regard the significant hardening response of chromium to nitrogen ion implantation can be environmentally beneficial from the standpoint of decreasing the thickness and the frequency of application of chromium plating. In this paper the results of a study of nitrogen ion implantation of chrome plated test flats using the non-line-of-sight Plasma Source Ion Implantation (PSII) process, are discussed. Surface characterization was performed using Scanning Electron Microscopy (SEM), Auger Electron Spectroscopy (AES), and Electron Spectroscopy for Chemical Analysis (ESCA). The surface properties were evaluated using a microhardness tester, a pin-on-disk wear tester, and a corrosion measurement system. Industrial field testing of nitrogen PSII treated chromium plated parts showed an improvement by a factor of two compared to the unimplanted case

  16. New Chromium Carbonyl Catalysts for [6+2] Cycloaddition Reactions

    OpenAIRE

    Kundig, Ernst Peter; Robvieux, Fabrice; Kondratenko, Mikhail

    2002-01-01

    The complexes, (benzene)chromiumdicarbonyl(methyl acrylate) and chromiumdicarbonylbis(cyclohexadiene), are precursors for the highly coordinatively unsaturated chromium dicarbonyl fragment 3, a catalyst for the cycloaddition of activated olefins to cycloheptatriene.

  17. Jõgevamaa ettevõtete TOP 55

    Index Scriptorium Estoniae

    2004-01-01

    Jõgevamaa ettevõtete TOP 55 aastal 2003. Käibe TOP 40. Kasumi TOP 40. Käibe kasvu TOP 20. Kasumi kasvu TOP 20. Rentaabluse TOP 20. Omakapitali tootlikkuse TOP 20. Jõgevamaa firmade üld- ja finantsandmed

  18. Comparative Biosorption Studies of Hexavalent Chromium Ion onto Raw and Modified Palm Branches

    Directory of Open Access Journals (Sweden)

    Mona A. Shouman

    2013-01-01

    Full Text Available The waste of palm branches (PB was tested for its ability to remove chromium (VI from aqueous solution by batch and column experiments. Palm branches chemically modified with an oxidizing agent (sulphuric acid then coated with chitosan and surfactant (hexadecyl trimethyl ammonium bromide surfactant, HDTMA, respectively, were carried out to improve the removal performance of PB. The results of their Cr (VI removal performances are pH dependent. The adsorption data could be well interpreted by the Langmuir, Freundlich, and Flory-Huggins isotherm models. The maximum adsorption capacity obtained from the Langmuir model for the chitosan coated oxidized palm branches is 55 mg/mg. The adsorption process could be described by pseudo-second-order kinetic model. The intraparticle diffusion study revealed that film diffusion might be involved. The biosorbents were successfully regenerated using 1 M HCL solution.

  19. On some properties of vanadium-, chromium- and manganese compounds under floatation

    International Nuclear Information System (INIS)

    Properties of compounds, formed by vanadium-, chromium- and manganese anions with quaternary ammonium bases (QAB) during their flotation separation from aqueous solutions are studied. Compounds of alcylbenzyldimethylammoniumchloride and alcyltrimethylammoniumchloride are used as surfactants. Optimum pH values in the case of vanadium flotation equal 25 to 5.5. Negatively charged vanadium polyanions interact with positively charged QAB hydrocarbon radical thus forming hydrophobic precipitates which are easil floated. Thermogravimetric analysis of the precipitate destruction process at heating has been used to show, that in the vanadium-containing compound the first stage of decomposition (low temperature) is less power-consuming, than the second one (high temperature). Vanadium containing precipitate decomposes with the formation of a metal phase. The supposition is made on the kinetics of chemical interaction between metal polyanions and cation-active collectors

  20. Iron(II modified natural zeolites for hexavalent chromium removal from contaminated water

    Directory of Open Access Journals (Sweden)

    Lofù Antonio

    2016-03-01

    Full Text Available Three different types of Fe(II-modified natural zeolites were tested as supports in continuous-flow columns for the treatment of Cr(VI contaminated water. The natural zeolites chosen as support were commercially available Zeosand (80% clinoptilolite, ATZ (79% phillipsite/chabazite, and ZS-55RW (90% Chabazite. All the examined modified zeolites turned out active for hexavalent chromium abatement, lowering its concentration below the European regulation level, even at relatively high flow rates (40 mL/h, linear velocity 15 cm/h. Zeosand, having a broader pH range of stability, was found to be the best one in terms of both Fe(II uptake (0.54 wt% and Cr removal (90 mg Cr/Kg zeolite.

  1. First observation of $^{55,56}$Zn

    CERN Document Server

    Giovinazzo, J; Borcea, C; Chartier, M; Czajkowski, S; De France, G; Grzywacz, R; Janas, Z; Lewitowicz, M; De Santos, F O; Pfützner, M; Pravikoff, M S; Thomas, J C

    2001-01-01

    In an experiment at the SISSI/LISE3 facility of GANIL, the most proton-rich zinc isotopes 55,56Zn have been observed for the first time. The experiment was performed using a high-intensity 58Ni beam at 74.5 MeV/nucleon impinging on a nickel target. The identification of 55,56Zn opens the way to 54Zn, a good candidate for two-proton radioactivity according to theoretical predictions.

  2. Biosorption of Chromium (VI) from Aqueous Solutions onto Fungal Biomass

    OpenAIRE

    Ismael Acosta R.; Xöchitl Rodríguez; Conrado Gutiérrez; Ma. de Guadalupe Moctezuma

    2004-01-01

    The biosorption of chromium (VI) on eighteen different natural biosorbents: Natural sediment, chitosan, chitin, Aspergillus flavus I-V, Aspergillus fumigatus I-ll, Helmintosporium sp, Cladosporium sp, Mucor rouxii mutant, M. rouxii IM-80, Mucor sp-I and 2, Candida albicans and Cryptococcus neoformans was studied in this work. It was found that the biomass of C. neoformans, natural sediment, Helmintosporium sp and chitosan was more efficient to remove chromium (VI) (determined spectrophotometr...

  3. Stainless Steel Leaches Nickel and Chromium into Foods During Cooking

    OpenAIRE

    Kamerud, Kristin L.; Hobbie, Kevin A.; Anderson, Kim A.

    2013-01-01

    Toxicological studies show that oral doses of nickel and chromium can cause cutaneous adverse reactions such as dermatitis. Additional dietary sources, such as leaching from stainless steel cookware during food preparation, are not well characterized. This study examined stainless steel grades, cooking time, repetitive cooking cycles, and multiple types of tomato sauces for their effects on nickel and chromium leaching. Trials included three types of stainless steels and a stainless steel sau...

  4. Genetic Predisposition for Dermal Problems in Hexavalent Chromium Exposed Population

    OpenAIRE

    Priti Sharma; Vipin Bihari; Agarwal, Sudhir K.; Goel, Sudhir K.

    2012-01-01

    We studied the effect of genetic susceptibility on hexavalent chromium induced dermal adversities. The health status of population was examined from the areas of Kanpur (India) having the elevated hexavalent chromium levels in groundwater. Blood samples were collected for DNA isolation to conduct polymorphic determination of genes, namely: NQO1 (C609T), hOGG1 (C1245G), GSTT1, and GSTM1 (deletion). Symptomatic exposed subjects (n = 38) were compared with asymptomatic exposed subjects (n = 108)...

  5. 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.

  6. 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

  7. DANGER OF HEXAVALENT CHROMIUM AND STRATEGY FOR THE REMEDITATION

    OpenAIRE

    Aniruddha Roy; Ayan Das; Nirmal Paul

    2013-01-01

    Some metals as micronutrients have a major role in the life and growth process of plants and animals. However, certain forms of some metals may also act as toxic material even in relatively small quantities. Chromium is such a metal, whose concentration above a certain limit may cause a serious problem to the health of living organisms. Chromium (Cr) may occur in several chemical forms in organic and inorganic systems. In biological systems only Cr (III) and Cr (VI) are signifi...

  8. 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.

  9. Stereology of carbide phase in modified hypereutectic chromium cast iron

    OpenAIRE

    J. Suchoń; A. Studnicki; M. Przybył

    2010-01-01

    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.

  10. Chromium reduction from slag on electromelting of stainless steel

    International Nuclear Information System (INIS)

    Specific features of chromium reduction from the slag on electromelting of stainless steel type Kh18N10T according to one- or two-slag procedure were studied. It was shown that one-slag melting technology allows double decrease of chromium losses in the form of incompletely reduced oxides. This occurs due to additional chemical reactions between metal and slag on their combined pouring into the ladle. 1 ref.; 3 figs

  11. 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...

  12. Evaluating trivalent chromium toxicity on wild terrestrial and wetland plants.

    Science.gov (United States)

    Lukina, A O; Boutin, C; Rowland, O; Carpenter, D J

    2016-11-01

    Elevated chromium levels in soil from mining can impact the environment, including plants. Mining of chromium is concentrated in South Africa, several Asian countries, and potentially in Northern Ontario, Canada, raising concerns since chromium toxicity to wild plants is poorly understood. In the first experiment, concentration-response tests were conducted to evaluate effects of chromium on terrestrial and wetland plants. Following established guidelines using artificial soil, seeds of 32 species were exposed to chromium (Cr(3+)) at concentrations simulating contamination (0-1000 mg kg(-1)). This study found that low levels of chromium (250 mg kg(-1)) adversely affected the germination of 22% of species (33% of all families), while higher levels (500 and 1000 mg kg(-1)) affected 69% and 94% of species, respectively, from 89% of the families. Secondly, effects on seedbanks were studied using soil collected in Northern Ontario and exposed to Cr(3+) at equivalent concentrations (0-1000 mg kg(-1)). Effects were less severe in the seedbank study with significant differences only observed at 1000 mg kg(-1). Seeds exposed to Cr(3+) during stratification were greatly affected. Seed size was a contributing factor as was possibly the seed coat barrier. This study represents an initial step in understanding Cr(3+) toxicity on wild plants and could form the basis for future risk assessments. PMID:27543852

  13. Wear resistance of chromium cast iron – research and application

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2006-04-01

    Full Text Available Purpose: A short characteristic of wear resistance chromium cast iron has been presented as well as possibilities of this material researches realization in Foundry Department have been discussed.Design/methodology/approach: Main attention was given on research process of crystallization and analysis of chromium cast iron microstructure and its resistance on erosion wears. Separate part of paper was devoted to discuss the bimetallic castings with chromium cast iron layer as well as typical applications of chromium cast iron castings in minig, proccesing, metallurgical and power industry.Findings: The new method of crystallization process research with three testers (DTA-K3 was found in the work. The method makes possible to characterize sensitivity of chromium cast iron on cooling kinetic.Research limitations/implications: DTA-K3 method can be used for research of crystallization proccess of cast materials particularly for abrasion-resisting alloy.Practical implications: Wide scope researches of chromium cast iron in Foundry Department enable extending applications its material in many industries.Originality/value: Value of the paper is the presentation of researches possibilities which undertaken in Foundry Department within the range of wear resistant materials.

  14. 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...

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

    OpenAIRE

    Mirković Nemanja; Draganjac Miroslav; Stamenković Dragoslav; Ristić Ljubiša

    2008-01-01

    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...

  16. USE OF TWO DIGESTION METHODS IN THE EVALUATION OF CHROMIUM CONTENT IN CATTLE'S MEAT SUPPLEMENTED WITH CHROMIUM CHELATES

    OpenAIRE

    R. L. T. Andrade; P.S.A. Moreira; R. Arruda; F. J. Lourenço; C. Palhari, F. F. Faria, V. B. Arevalo; Faria, F. F.; V. B. Arevalo

    2015-01-01

    The present study aimed to analyze the chromium content in beef using two digestion methods. There were used samples from 24 18-month-old male cattle, and twelve of them were supplemented and twelve were not supplemented with chromium chelate. These samples were evaluated by atomic absorption spectroscopy, previously submitted to digestion method using nitric acid (65%) with hydrogen peroxide (35%) and to digestion method, using solution of nitric perchloric acid in the proportion 3:1. Immedi...

  17. Activation of bentonite to remove the chromium from waste water produced by panning industry, and studying the chromium recovery efficiency

    International Nuclear Information System (INIS)

    The fast development of tanning industry led to an increase in environmental problems resulting from discharging its wastes to the surrounding environment. Thus solving this problem became one of the most important aims that the researchers work on. The chromium content of the industrial water wastes of the tanning industry considered as the main pollutant for the environment. The Aleppo Bentonite is used in early research to remove the chromium from the industrial waste water.The current research aims to find a method to activate the Aleppo Bentonite in order to increase the effective removal of chromium from the industrial waste water which is produced by tanning industry, as well as to specify the optimal conditions for chromium recovery.This study used the Aleppo Bentonite, whose origin is Tal Ajar-Aleppo to study the activation aspects using Sulfuric Acid, Hydrochloric Acid and Nitric Acid, in addition to study the recovery aspects using the same acids and hydrogen peroxide and to specify the optimal conditions for chromium recovery through applying some experiments based on three main factors: concentration, settling time and temperature.It was observed from the applied experiments that it is possible to recover chromium from Bentonite efficiently up to (80% - 90%) by treating the Bentonite with hydrogen peroxide(33% concentration) at room temperature, or by treating it with hydrogen peroxide(8.25% concentration) at 75oC, while the settling time factor proved that full recovery of chromium is obtained during the first hour, and increasing the time factor does not affect the efficiency of chromium recovery. (author)

  18. The influence of chromium on structure and mechanical properties of B2 nickel aluminide alloys. Ph.D. Thesis - Florida Univ., 1991 Final Report

    Science.gov (United States)

    Cotton, James Dean

    1992-01-01

    Major obstacles to the use of NiAl-based alloys and composites are low ductility and toughness. These shortcomings result in part from a lack of sufficient slip systems to accommodate plastic deformation of polycrystalline material (von Mises Criterion). It has been reported that minor additions of chromium to polycrystalline NiAl cause the predominant slip system to shift from the usual. If true, then a major step toward increasing ductility in this compound may be realized. The purpose of the present study was to verify this phenomenon, characterize it with respect to chromium level and Ni to Al ratio, and correlate any change in slip system with microstructure and mechanical properties. Compression and tensile specimens were prepared from alloys containing 0 to 5 percent chromium and 45 to 55 percent aluminum. Following about one percent strain, transmission electron microscopy foils were produced and the slip systems determined using the g x b = 0 invisibility criterion. Contrary to previous results, chromium was found to have no effect on the preferred slip system of any of the alloys studied. Possible reasons for the inconsistency of the current results with previous work are considered. Composition-structure-property relationships are discerned for the alloys, and good correlation are demonstrated in terms of conventional strengthening models for metallic systems.

  19. Comparison of the Spectral Characteristics of Chromium-Containing Crystals of the Calcium Gallogermanate Type with Their Structural Features

    International Nuclear Information System (INIS)

    The molecular refractions and characteristics of the circular dichroism spectra of unactivated and chromiumactivated La3Ga5.5Ta0.5O14, La3Ga5.5Nb0.5O14, La3Ga5GeO14, La3Ga5SiO14, Sr3Ga2Ge4O14, and Ca3Ga2Ge4O14crystals are compared with their structural parameters. Correlations between the molecular refractions and the structural distortions responsible for the optical activity of crystals and correlations between the characteristics of circular dichroism bands of defects and chromium ions and the interatomic distances in polyhedra and their distortions are found. The calcium gallogermanate structures exhibit a unique correspondence between the electronic configuration of host ions and the local symmetry.

  20. Scientific Opinion on chromium(III) lactate tri-hydrate as a source of chromium added for nutritional purposes to foodstuff

    OpenAIRE

    EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS)

    2012-01-01

    The Panel on Food Additives and Nutrient Sources added to Food provides a scientific opinion on the safety and bioavailability of chromium(III) lactate tri-hydrate as a source of chromium(III) added for nutritional purposes to foodstuffs. The safety of chromium itself, in terms of the amounts that may be consumed, is outside the remit of this Panel. No new data have been provided as regards the safety and bioavailability of chromium from chromium(III) lactate tri-hydrate. The Panel c...

  1. Creep deformation of TD--nickel chromium

    International Nuclear Information System (INIS)

    The creep behavior of thoria dispersed nickel-chromium (TD-NiCr) was examined at 10930C. Major emphasis was placed on 1) the effects of the material and the test related variables (grain size, temperature, stress, strain and strain rate) on the deformation characteristics, and 2) the evaluation of single crystal TD-NiCr material produced by a directional recrystallization technique. Creep activation enthalpies were found to increase with increasing grain size reaching maximum values for the single crystal TD-NiCr. Stress exponent of the steady state creep rate was also significantly higher for the single crystal material as compared with that determined for the polycrystalline TD-NiCr. The elevated temperature deformation of TD-NiCr was analyzed in terms of two parallel-concurrent processes: 1) diffusion controlled grain boundary sliding and 2) dislocation motion. The characteristics of the dislocation motion deformation mode (as observed in the single crystal TD-NiCr) suggest that strong particle-dislocation interactions are present. The relative contributions of dislocation motion and grain boundary sliding in TD-NiCr were estimated. In creep, grain boundary sliding was found to predominate for the small, equiaxed grain structures, whereas the dislocation deformation mode became significant for only the large grain TD-NiCr and the single crystal material

  2. Low energy spin excitations in chromium metal

    Energy Technology Data Exchange (ETDEWEB)

    Pynn, R. [Los Alamos National Lab., NM (United States); Azuah, R.T. [Hahn-Meitner-Inst., Berlin (Germany); Stirling, W.G. [Univ. of Liverpool (United Kingdom). Dept. of Physics; Kulda, J. [Inst. Laue Langevin, Grenoble (France)

    1997-12-31

    Neutron scattering experiments with full polarization analysis have been performed with a single crystal of chromium to study the low-energy spin fluctuations in the transverse spin density wave (TSDW) state. A number of remarkable results have been found. Inelastic scattering observed close to the TSDW satellite positions at (1 {+-} {delta},0,0) does not behave as expected for magnon scattering. In particular, the scattering corresponds to almost equally strong magnetization fluctuations both parallel and perpendicular to the ordered moments of the TSDW phase. As the Neel temperature is approached from below, scattering at the commensurate wavevector (1,0,0) increases in intensity as a result of critical scattering at silent satellites (1,0, {+-} {delta}) being included within the spectrometer resolution function. This effect, first observed by Sternlieb et al, does not account for all of the inelastic scattering around the (1,0,0) position, however, Rather, there are further collective excitations, apparently emanating from the TSDW satellites, which correspond to magnetic fluctuations parallel to the ordered TSDW moments. These branches have a group velocity that is close to that of (1,0,0) longitudinal acoustic (LA) phonons, but assigning their origin to magneto-elastic scattering raises other unanswered questions.

  3. 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.

  4. A Rare Terminal Dinitrogen Complex of Chromium

    International Nuclear Information System (INIS)

    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.

  5. Hexavalent Chromium Reduction and Its Distribution in the Cell and Medium by Chromium Resistant Fusarium solani

    Directory of Open Access Journals (Sweden)

    Mousumi Sen

    2013-01-01

    Full Text Available In the present work, batch biosorption of Cr(VI was studied using the fungal strain isolated from soil. The fungal strain was characterized as Fusarium solani. The total Cr distribution in the biomass (fungus and in the media obtained from the experiment conducted at 500 mg l -1 initial Cr(VI concentration and pH 5.0. The results indicated both intracellular and extracellular accumulation and enzymatic reduction of Cr(VI and this was supported by the Transmission Electron Microscopic (TEM observation at the same Cr(VI concentration and pH value. Chromium elution from Fusarium solani containing Cr was then tried out using a number of chromium eluting reagents and a maximum Cr could be eluted using 0.5N sodium hydroxide solution without destructing the biomass structure. The total Cr was recovered by pH adjustment from both biomass and media was found to be 44% of the initial Cr(VI concentration (500 mg l-1.

  6. Electron transfer. 75. Reduction of carboxylato-bound chromium(V) with vanadium(IV). Intervention of chromium(IV)

    International Nuclear Information System (INIS)

    The chelated (carboxylato)chromium(V) anion bis(2-hydroxy-2-ethylbutyrato)oxochromate(V) (I), [(Lig)2Cr(O)]-, reacts with oxovanadium(IV) to form a strongly absorbing species (lambda/sub max/ = 515 nm; epsilon = 1.7 x 103 M-1) in the presence of 2-hydroxy-2-ethylbutyric acid buffers (pH 2-4). EPR data support 1:1 stoichiometry with VO2+ in deficiency, indicating the formation of a chromium(IV) species by reduction. With excess VO2+ a chromium(III) product was obtained. Spectral and ion-exchange properties of this product correspond to those observed for the titanium(III) and iron(II) reductions of chromium(V) and are consistent with the formulation of the product as a bis(hydroxycarboxylate) chelate of (H2O)2Cr/sup III/. With excess vanadium(IV), the reaction exhibits triphasic kinetics. The remaining step of the reaction is the reduction of the chromium(IV) intermediate with VO2+. Rates for all steps increase with decreasing [H+] and level off at low [H+]. The limiting rate constants for the formation of the chromium(IV) intermediate by the (Lig)3Cr(O)2- and (Lig)2Cr(O)- pathways are 2.8 x 103 and 2.2 x 102 M-1s-1. The bimolecular limiting rate constant for the reduction of chromium(IV) is computed to be 7.7 x 102 M-1 s-1. 33 references, 7 tables

  7. Chromium propionate enhances adipogenic differentiation of bovine intramuscular adipocytes

    Directory of Open Access Journals (Sweden)

    Rebecca eTokach

    2015-09-01

    Full Text Available In vitro experiments were performed to determine the effects of increasing concentrations of chromium propionate on mRNA and protein abundance of different enzymes and receptors. Intramuscular and subcutaneous preadipocytes and bovine satellite cells were isolated from the longissimus muscle to determine the effect of treatment on glucose transporter type 4 (GLUT4 and peroxisome proliferator-activated receptor γ mRNA and GLUT4 protein abundance. Preadipocyte cultures were treated with differentiation media plus either sodium propionate or different concentrations of chromium propionate (CrPro for 96, 120, and 144 h before harvest. This study indicated adipogenesis of the bovine intramuscular adipocytes were more sensitive to the treatment of chromium propionate as compared to subcutaneous adipocytes. Enhancement of adenosine monophosphate-activated protein kinase and GLUT4 mRNA by CrPro treatment may enhance glucose uptake in intramuscular adipocytes. Chromium propionate decreased GLUT4 protein levels in muscle cell cultures suggesting those cells have increased efficiency of glucose uptake due to exposure to increased levels of CrPro. In contrast, each of the two adipogenic lines had opposing responses to the CrPro. It appeared that CrPro had the most stimulative effect of GLUT4 response in the intramuscular adipocytes as compared to subcutaneous adipocytes. These findings indicated opportunities to potentially augment marbling in beef cattle fed chromium propionate during the finishing phase.

  8. Anthropogenic chromium emissions in china from 1990 to 2009.

    Science.gov (United States)

    Cheng, Hongguang; Zhou, Tan; Li, Qian; Lu, Lu; Lin, Chunye

    2014-01-01

    An inventory of chromium emission into the atmosphere and water from anthropogenic activities in China was compiled for 1990 through to 2009. We estimate that the total emission of chromium to the atmosphere is about 1.92×10⁵ t. Coal and oil combustion were the two leading sources of chromium emission to the atmosphere in China, while the contribution of them showed opposite annual growth trend. In total, nearly 1.34×10⁴ t of chromium was discharged to water, mainly from six industrial categories in 20 years. Among them, the metal fabrication industry and the leather tanning sector were the dominant sources of chromium emissions, accounting for approximately 68.0% and 20.0% of the total emissions and representing increases of 15.6% and 10.3% annually, respectively. The spatial trends of Cr emissions show significant variation based on emissions from 2005 to 2009. The emission to the atmosphere was heaviest in Hebei, Shandong, Guangdong, Zhejiang and Shanxi, whose annual emissions reached more than 1000t for the high level of coal and oil consumption. In terms of emission to water, the largest contributors were Guangdong, Jiangsu, Shandong and Zhejiang, where most of the leather production and metal manufacturing occur and these four regions accounted for nearly 47.4% of the total emission to water. PMID:24505309

  9. Anthropogenic chromium emissions in china from 1990 to 2009.

    Directory of Open Access Journals (Sweden)

    Hongguang Cheng

    Full Text Available An inventory of chromium emission into the atmosphere and water from anthropogenic activities in China was compiled for 1990 through to 2009. We estimate that the total emission of chromium to the atmosphere is about 1.92×10⁵ t. Coal and oil combustion were the two leading sources of chromium emission to the atmosphere in China, while the contribution of them showed opposite annual growth trend. In total, nearly 1.34×10⁴ t of chromium was discharged to water, mainly from six industrial categories in 20 years. Among them, the metal fabrication industry and the leather tanning sector were the dominant sources of chromium emissions, accounting for approximately 68.0% and 20.0% of the total emissions and representing increases of 15.6% and 10.3% annually, respectively. The spatial trends of Cr emissions show significant variation based on emissions from 2005 to 2009. The emission to the atmosphere was heaviest in Hebei, Shandong, Guangdong, Zhejiang and Shanxi, whose annual emissions reached more than 1000t for the high level of coal and oil consumption. In terms of emission to water, the largest contributors were Guangdong, Jiangsu, Shandong and Zhejiang, where most of the leather production and metal manufacturing occur and these four regions accounted for nearly 47.4% of the total emission to water.

  10. Enhancement of chromium uptake in tanning using oxazolidine.

    Science.gov (United States)

    Sundarapandiyan, S; Brutto, Patrick E; Siddhartha, G; Ramesh, R; Ramanaiah, B; Saravanan, P; Mandal, A B

    2011-06-15

    Monocyclic and bicyclic oxazolidines were offered at three different junctures of chrome tanning process viz. prior to BCS offer, along with BCS and after basification. It was found that oxazolidine when offered after basification brought about better chromium uptake and reduction of chromium load in the wastewater. Offer of oxazolidine was also varied. Increase in offer of oxazolidine from 0.25% to 1% was found to enhance the chromium uptake and decrease the chromium load in wastewater. But the increase in uptake was not proportionate to the increase in oxazolidine offer more than 0.75%. Offer of 1% Zoldine ZA 78 (monocyclic oxazolidine) and Zoldine ZE (bicyclic oxazolidine) after basification brought about 63.4% and 73.1% enhancement in chrome content in leather compared to control where oxazolidine was not offered. The tone of the wetblue was found to be altered moderately. However this did not call for any process adjustments in wet-finishing. The oxazolidine treated leathers were found to be immensely fuller and tighter. It was found experimentally that offer of 1% of oxazolidine facilitated reduction in the offer of syntans administered for filling and grain tightening by around 46%. Oxazolidine could bring about significant reduction in cost of chemicals apart from resulting environmental benefits due to enhancement of chromium uptake during tanning. PMID:21536383

  11. Low-chromium reduced-activation ferritic steels for fusion

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L.; Alexander, D.J.; Kenik, E.A. [Oak Ridge National Laboratory, TN (United States)

    1996-04-01

    Development of reduced-activation ferritic steels has concentrated on high-chromium (8-10 wt% Cr) steels. However, there are advantages for a low-chromium steel, and initial ORNL studies on reduced-activation steels were on compositions with 2.25 to 12% Cr. Those studies showed an Fe-2.25Cr-2W-0.25V-0.1C (2 1/4Cr-2WV) steel to have the highest strenglth of the steels studied. Although this steel had the best strength, Charpy impact properties were inferior to those of an Fe-9Cr-2W-0.25V-0.07Ta-0.1C (9Cr-2WVTa) and an Fe-2.25Cr-2W-0.1C (2 1/4Cr-2W) steel. Therefore, further development of the low-chromium Cr-W steels was required. These results indicate that it is possible to develop low-chromium reduced-activation ferritic steels that have tensile and impact properties as good or better than those of high-chromium (7-9% Cr) steels. Further improvement of properties should be possible by optimizing the composition.

  12. 21 CFR 558.55 - Amprolium.

    Science.gov (United States)

    2010-04-01

    ... Federal Register citations affecting § 558.55, see the List of CFR Sections Affected, which appears in the...; improving pigmentation; as an aid in the prevention of infectious coryza Feed for 7 to 14 d; withdraw 5 d... coryza Feed for 7 to 14 d; withdraw 24 h before slaughter. Feed according to subtable in item (i)...

  13. 27 CFR 9.55 - Bell Mountain.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bell Mountain. 9.55... Mountain. (a) Name. The name of the viticultural area described in this section is “Bell Mountain.” (b) Approved map. The appropriate map for determining the boundaries of the Bell Mountain viticultural area...

  14. 10 CFR 55.27 - Documentation.

    Science.gov (United States)

    2010-01-01

    ... REGULATORY COMMISSION (CONTINUED) OPERATORS' LICENSES Medical Requirements § 55.27 Documentation. The facility licensee shall document and maintain the results of medical qualifications data, test results, and each operator's or senior operator's medical history for the current license period and provide...

  15. 9 CFR 55.24 - Herd status.

    Science.gov (United States)

    2010-01-01

    ... available for testing (i.e., a trace animal from a known positive herd died and was not tested) or for other... with program requirements for animal identification, animal testing, and recordkeeping, the herd will... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Herd status. 55.24 Section...

  16. 28 CFR 0.55 - General functions.

    Science.gov (United States)

    2010-07-01

    .... 1171 et seq., including registration thereunder. (See also 28 CFR 3.2) (i) All civil proceedings... enforcement operation. Editorial Note: For Federal Register citations affecting § 0.55, see the List of CFR..., locomotive inspection (45 U.S.C. 22, 23, 28-34), the Organized Crime Control Act of 1970, prison-made...

  17. 46 CFR 503.55 - Derivative classification.

    Science.gov (United States)

    2010-10-01

    ... markings prescribed by 32 CFR 2001.20 through 2001.23 and shall otherwise conform to the requirements of 32 CFR 2001.20 through 2001.23. ... 46 Shipping 9 2010-10-01 2010-10-01 false Derivative classification. 503.55 Section...

  18. 7 CFR 1786.55 - Application procedure.

    Science.gov (United States)

    2010-01-01

    ... AGRICULTURE (CONTINUED) PREPAYMENT OF RUS GUARANTEED AND INSURED LOANS TO ELECTRIC AND TELEPHONE BORROWERS Special Discounted Prepayments on RUS Direct/Insured Loans § 1786.55 Application procedure. Any borrower seeking to prepay its RUS Notes under this subpart should apply to the appropriate RUS Area Director...

  19. Locks & keys service moves to building 55

    CERN Multimedia

    2012-01-01

    Please note that as of July 12 Locks & keys service will be at building 55 second floor. The opening hours are as follows: 08:30 am to 12:30 pm - 1:30 pm to 5:30 pm. The procedures and rules relating to applications for key and cylinder have not changed. GI-IS Group

  20. 33 CFR 151.55 - Recordkeeping requirements.

    Science.gov (United States)

    2010-07-01

    ... (CONTINUED) POLLUTION VESSELS CARRYING OIL, NOXIOUS LIQUID SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE... Antarctic Treaty as it Pertains to Pollution from Ships Garbage Pollution and Sewage § 151.55 Recordkeeping...) Plastic material. (ii) Floating dunnage, lining, or packing material. (iii) Ground paper products,...

  1. FORMATION AND DESTRUCTION OF HEXAVALENT CHROMIUM IN A LABORATORY SWIRL FLAME INCINERATOR

    Science.gov (United States)

    The partitioning of chromium (Cr) in combustion systems was investigated theoretically and experimentally. Theoretical predictions were based on chemical equilibrium and suggested that hexavalent chromium [Cr(VI)] was favored by the presence of chlorine (Cl) and diminished by the...

  2. Chromium solubility in anhydrous Phase B

    Science.gov (United States)

    Bindi, Luca; Sirotkina, Ekaterina A.; Bobrov, Andrey V.; Nestola, Fabrizio; Irifune, Tetsuo

    2016-02-01

    The crystal structure and chemical composition of a crystal of (Mg14- x Cr x )(Si5- x Cr x )O24 ( x ≈ 0.30) anhydrous Phase B (Anh-B) synthesized in the model system MgCr2O4-Mg2SiO4 at 12 GPa and 1600 °C have been investigated. The compound was found to be orthorhombic, space group Pmcb, with lattice parameters a = 5.900(1), b = 14.218(2), c = 10.029(2) Å, V = 841.3(2) Å3 and Z = 2. The structure was refined to R 1 = 0.065 using 1492 independent reflections. Chromium was found to substitute for both Mg at the M3 site (with a mean bond distance of 2.145 Å) and Si at the octahedral Si1 site (mean bond distance: 1.856 Å), according to the reaction Mg2+ + Si4+ = 2Cr3+. Such substitutions cause a reduction in the volume of the M3 site and an increase in the volume of the Si-dominant octahedron with respect to the values typically observed for pure Anh-B and Fe2+-bearing Anh-B. Taking into account that Cr3+ is not expected to be Jahn-Teller active, it appears that both the Cr3+-for-Mg and Cr3+-for-Si substitutions in the Anh-B structure decrease the distortion of the octahedra. Electron microprobe analysis gave the Mg13.66(8)Si4.70(6)Cr0.62(4)O24 stoichiometry for the studied phase. The successful synthesis of this phase provides new information for the possible mineral assemblages occurring in the Earth's deep upper mantle and shed new light on the so-called X discontinuity that has been observed at 275-345 km depth in several subcontinental and subduction zone environments.

  3. Scientific Opinion on chromium(III lactate tri-hydrate as a source of chromium added for nutritional purposes to foodstuff

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS

    2012-10-01

    Full Text Available

    The Panel on Food Additives and Nutrient Sources added to Food provides a scientific opinion on the safety and bioavailability of chromium(III lactate tri-hydrate as a source of chromium(III added for nutritional purposes to foodstuffs. The safety of chromium itself, in terms of the amounts that may be consumed, is outside the remit of this Panel. No new data have been provided as regards the safety and bioavailability of chromium from chromium(III lactate tri-hydrate. The Panel concurs with its earlier views stating that no evidence was provided supporting the bioavailability of chromium from chromium(III lactate tri-hydrate. Chromium(III lactate tri-hydrate is claimed to be freely soluble in water, however, chromium(III lactate tri-hydrate exists as a weak complex that may influence the bioavailability of chromium(III in the gastrointestinal tract. The Panel re-iterates that because of the complex chemistry of chromium(III lactate tri-hydrate in aqueous solutions and its limited solubility at pH >5, the bioavailability of chromium(III from chromium(III lactate tri-hydrate is low. Based on a conservative exposure estimate, the Panel calculated the combined intake of chromium(III from supplements and from foods fortified with chromium(III lactate tri-hydrate, for both adults and children, to be approximately 240 μg chromium(III/day, which is below the value of 250 µg/day established by the WHO for supplemental intake of chromium that should not be exceeded. The Panel noted that the use of chromium(III lactate tri-hydrate in the form of a premix with lactose, added to foods, would result in an exposure at the mean for adults of approximately 7-37 mg lactose/day (0.12-0.62 μg lactose/kg bw/day and to 36-192 μg lactate/day (0.60-3.20 μg/kg bw/day. Given that subjects with lactose maldigestion will tolerate up to 12 g of lactose with no or minor symptoms, these levels are not of safety concern.

  4. Biosorption of hexavalent chromium in a tannery industry wastewater using fungi species

    OpenAIRE

    Sivakumar, D.

    2016-01-01

    The isolated fungi species of different kinds from chromium contaminated soil sites located in Nagalkeni, Chennai were used for reducing chromium(VI) in a tannery industry wastewater of Nagalkeni, Chennai.  The experiments were conducted to know biosorption potential of isolated fungi species for removing chromium(VI) in a tannery industry wastewater against the different pH, fungi biomass and chromium(VI) concentration (dilution ratio).  The results of this study indicated that the order of ...

  5. Investigation of hexavalent chromium removal from Synthetic wastewater by using Peaganum

    OpenAIRE

    Ali Akbar Taghizadeh; Maryam khodadadi; Taher Shahriary; Hadighe Dorri; mahla zaferanieh; rasoul khosravi

    2012-01-01

    Background and Aim: Discharge of industrial wastewater containing hexavalent chromium into the environment can have harmful effects to the types of organisms. So, chromium should remove before discharging to the environment with an effective method. The purpose of this study of is hexavalent chromium removed with Peganum harmala granular seeds(PGS).   Materials and Methods: In this experimental study, The removal of hexavalent chromium with using PGS, with changes in time, pH, adsorbent dose,...

  6. Chromium Exposure and Hygienic Behaviors in Printing Workers in Southern Thailand

    OpenAIRE

    Somsiri Decharat

    2015-01-01

    Objectives. The main objective of this study was to assess the chromium exposure levels in printing workers. The study evaluated the airborne, serum, and urinary chromium levels and determines any correlation between level of chromium in specimen and airborne chromium levels. Material and Methods. A cross-sectional study was conducted with 75 exposed and 75 matched nonexposed subjects. Air breathing zone was measured by furnace atomic absorption spectrophotometer. Serum and urine samples were...

  7. Structure and morphology studies of chromium film at elevated temperature in hypersonic environment

    OpenAIRE

    Hegde, GM; Kulkarni, V; Nagaboopathy, M; Reddy, KPJ

    2012-01-01

    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. Surface morphology changes of chromium coating have been studied using scanning electron microscopy (SEM) before and after shock heating. Significant amount of chromium ablation and sub...

  8. Cutaneous absorption of trivalent chromium: tissue levels and treatment by exchange transfusion

    OpenAIRE

    Kelly, W F; Ackrill, P; Day, J P; O'Hara, Maureen; Tye, C T; Burton, I.; Orton, C.; Harris, M.

    1982-01-01

    ABSTRACT A man was accidentally immersed in hot acidic trivalent chromium sulphate solution but none was swallowed. The clinical course was dominated by burns, intravascular haemolysis, and acute renal failure. Blood concentrations of chromium were measured during treatment and tissue concentrations were measured at death. Exchange transfusion reduced blood chromium concentrations by two-thirds. The total quantities of chromium absorbed and removed by various routes were calculated. In-vitro ...

  9. The risk to groundwater from wastewater irrigation using high chromium tannery effluent

    OpenAIRE

    Stuart, M E; Milne, C. J.

    2001-01-01

    Wastewater from Leon containing high concentrations of chromium from the tanning industry is used to irrigate agricultural land overlying an aquifer used for to supply potable water. Chromium from irrigation water is accumulating in agricultural soils, and in the lagoon and canal sediments, but groundwater appears to be unaffected and chromium concentrations remain low. A limited area of very high chromium concnetrations in groundwater was confirmed to be derived from a factory supplying the ...

  10. Liver Toxicity Resulted From Ingestion of Chromium Picolinate

    Directory of Open Access Journals (Sweden)

    Baltacı D et al.

    2010-03-01

    Full Text Available Herein, liver toxicity resulted from chronic ingestion of chromium picolinate, recommended daily allowance of over-the-counter (OTC have been presented. A woman of 32 years-old presented with pruritis since three days. On physical examination, she had no skin rashes, discoloration and urticarial lesions. With detailed inquiry of the patient, it has been determined that she had been using over-the-counter medicine containing chromium picolinate to enhance weight loss and increase lean body mass. On blood test examination follows: ALT: 484 U/I, AST: 182, Total/direct Bilirubin: 0,43/0,88 mg/dl. Complete Blood Count (CBC was normal. Chromium supplements may cause serious liver function impairment although when ingested within normal doses. Medication histories should include attention to the use of OTC nutritional supplements.

  11. Influence of chromium, oxygen, carbon and nitrogen on iron viscosity

    International Nuclear Information System (INIS)

    Kinetic viscosity of 70 beforehand melted iron samples with additions of chromium (up to 2%) and carbon (up to 1%) has been investigated. Different conditions of melting brought about differences in oxygen and nitrogen contents. Viscosity of most samples has been determined in the 1550-1650 deg C temperature range. It is stated that small additions to pure iron of each of the investigated elements (O, Cr, C, N) decrease its viscosity. Combined effect of these additions on viscosity is inadditive. Simultaneous introduction of oxygen and carbon may result in increase of melt viscosity. The same fact is observed at combined introduction of chromium and nitrogen. Simultaneous introduction of other impurities-chromium with oxygen or carbon, nitrogen with oxygen causes amplification of their individual effect. Reasons for the observed regularities result from changes in energies of interparticle interactions in the melt and therefore rebuilding of structure of its short-range order

  12. A study of the process of desorption of hexavalent chromium

    Directory of Open Access Journals (Sweden)

    W.B. Amorim

    2003-09-01

    Full Text Available In this work the process of desorption of hexavalent chromium, a toxic metal ion, from the marine algae Sargassum sp, following biosorption experiments 2³ factorial design was studied. A technique was applied to three eluents: HCl, H2SO4 and EDTA. Three factors of importance were evaluated: concentration of eluent, the ratio between mass of biosorbent and volume of eluent (S/L and process time. A statistical analysis of the experimental results showed that the three variables evaluated are significant for all three eluents. The models for chromium desorption were validated, as the results agreed well with the observed values. Through use of the response surface methodology, a factorial design based optimization technique; it was possible to identify the most suitable eluent and the interval of values for the process variables that resulted in the most significant desorption of chromium, which is relevant information for work aiming at process optimization.

  13. Structural and magnetic properties of chromium doped zinc ferrite

    International Nuclear Information System (INIS)

    Zinc chromium ferrites with chemical formula ZnCrxFe2−xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by Sol - Gel technique. The structural as well as magnetic properties of the synthesized samples have been studied and reported here. The structural characterizations of the samples were analyzed by using X – Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and Transmission Electron Microscope (TEM). The single phase spinel cubic structure of all the prepared samples was tested by XRD and FTIR. The particle size was observed to decrease from 18.636 nm to 6.125 nm by chromium doping and induced a tensile strain in all the zinc chromium mixed ferrites. The magnetic properties of few samples (x = 0.0, 0.4, 1.0) were investigated using Vibrating Sample Magnetometer (VSM)

  14. Chromium Resistant Bacteria: Impact on Plant Growth in Soil Microcosm

    Directory of Open Access Journals (Sweden)

    Sayel Hanane

    2014-07-01

    Full Text Available Three chromium resistant bacterial strains, Pseudomonas fluorescens PF28, Enterobacter amnigenus EA31 and Enterococcus gallinarum S34 isolated from tannery waste contaminated soil were used in this study. All strains could resist a high concentration of K2Cr2O7 that is up to 300 mg/L. The effect of these strains on clover plants (Trifolium campestre in the presence of two chromium salts CrCl3 and K2Cr2O7 was studied in soil microcosm. Application of chromium salts adversely affected seed germination, root and shoot length. Bacterial inoculation improved the growth parameters under chromate stress when compared with non inoculated respective controls. There was observed more than 50% reduction of Cr(VI in inoculated soil microcosms, as compared to the uninoculated soil under the same conditions. The results obtained in this study are significant for the bioremediation of chromate pollution.

  15. Studies of removal of chromium by model constructed wetland

    Directory of Open Access Journals (Sweden)

    C. Mant

    2005-09-01

    Full Text Available Chromium is a pollutant present in tannery wastewater, its removal is necessary for protection of the environment. Penisetum purpureum, Brancharia decumbens and Phragmites australis were grown hydroponically in experimental gravel beds to determine their potential for the phytoremediation of solutions containing 10 and 20 mg Cr dm-3. These concentrations, similar to tannery wastewater after initial physico-chemical treatment were used with the aim of developing an economic secondary treatment to protect the environment. All the systems achieved removal efficiencies of 97 - 99.6% within 24 hours. P. purpureum and B. decumbens removed 78.1% and 68.5% respectively within the first hour. Both P. purpureum and B. decumbens were tolerant of the concentrations of chromium applied, but P. purpureum showed the greatest potential because its faster growth and larger biomass achieved a much greater chromium removal over the whole length of time of the experiment.

  16. On the rational alloying of structural chromium-nickel steels

    International Nuclear Information System (INIS)

    A study was made on the influence of chromium nickel, phosphorus on the critical brittleness temperature of Cr-Ni-Mo-V structural steels. It is shown that the critical brittleness temperature of these steels increases at chromium content more over than 2% and nickel content more than 2% in the result of carbide transformations during tempering. Increase of nickel content in Cr-Ni-Mo-V-steels strengthens the tendency to embrittlement during slow cooling, from tempering temperature owing to development of process of phosphorus grain-boundary segregation. Two mentioned mechanisms of embrittlement determine principles of rational steel alloying. The extreme dependence of the critical brittleness temperature on chromium and nickel content, which enables to choose the optimum composition of Cr-Ni-Mo-V-steels, was established

  17. Chromium accumulation by the hyperaccumulator plant Leersia hexandra Swartz.

    Science.gov (United States)

    Zhang, Xue-Hong; Liu, Jie; Huang, Hai-Tao; Chen, Jun; Zhu, Yi-Nian; Wang, Dun-Qiu

    2007-04-01

    Leersia hexandra Swartz (Gramineae), which occurs in Southern China, has been found to be a new chromium hyperaccumulator by means of field survey and pot-culture experiment. The field survey showed that this species had an extraordinary accumulation capacity for chromium. The maximum Cr concentration in the dry leaf matter was 2978 mg kg(-1) on the side of a pond near an electroplating factory. The average concentration of chromium in the leaves was 18.86 times as that in the pond sediment, and 297.41 times as that in the pond water. Under conditions of the nutrient solution culture, it was found that L. hexandra had a high tolerance and accumulation capacity to Cr(III) and Cr(VI). Under 60 mg l(-1) Cr(III) and 10 mg l(-1) Cr(VI) treatment, there was no significant decrease of biomass in the leaves of L. hexandra (p>0.05). The highest bioaccumulation coefficients of the leaves for Cr(III) and Cr(VI) were 486.8 and 72.1, respectively. However, L. hexandra had a higher accumulation capacity for Cr(III) than for Cr(VI). At the Cr(III) concentration of 10 mg l(-1) in the culture solution, the concentration of chromium in leaves was 4868 mg kg(-1), while at the same Cr(VI) concentration, the concentration of chromium in leaves was only 597 mg kg(-1). These results confirmed that L. hexandra is a chromium hyperaccumulator which grows rapidly with a great tolerance to Cr and broad ecological amplitude. This species could provide a new plant resource that explores the mechanism of Cr hyperaccumulation, and has potential for usage in the phytoremediation of Cr-contaminated soil and water. PMID:17207838

  18. Heat resistance of carbon steel with chromium-based gas-thermal sprayed coatings

    International Nuclear Information System (INIS)

    Heat resistance of steel with chromium-base plasma sprayed coating is studied in comparison with chromium coating and base material. The specimens were oxidized at the air under 1250 K during 48 h. Investigations into steel-chromium coating interface were carried out and the structure of cinder was studied. Refs. 7, figs. 2

  19. Evaluation of flexural bond strength of porcelain to used nickel-chromium alloy in various percentages

    Directory of Open Access Journals (Sweden)

    VNV Madhav

    2012-01-01

    Fresh nickel-chromium alloy shows the greatest porcelain adherence.There is no significant change in bond strength of ceramic to alloy with up to 75% of used nickel-chromium alloy.At least 25%- of new alloy should be added when recycled nickel-chromium alloy is being used for metal ceramic restorations.

  20. 75 FR 60454 - Draft Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the...

    Science.gov (United States)

    2010-09-30

    ... AGENCY Draft Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the..., ``Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the Integrated Risk..., 2010. The listening session on the draft assessment for hexavalent chromium will be held on November...

  1. 76 FR 20349 - Draft Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the...

    Science.gov (United States)

    2011-04-12

    ... AGENCY Draft Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the..., ``Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the Integrated Risk... workshop on the draft assessment for Hexavalent Chromium will be held on May 12, 2011, beginning at 8:30...

  2. 77 FR 61431 - Hexavalent Chromium Standards; Extension of the Office of Management and Budget's (OMB) Approval...

    Science.gov (United States)

    2012-10-09

    ... Occupational Safety and Health Administration Hexavalent Chromium Standards; Extension of the Office of...) approval of the information collection requirements specified in the Hexavalent Chromium Standards for... requirements specified in the Hexavalent Chromium (Cr(VI)) Standards for General Industry (29 CFR...

  3. 21 CFR 73.3110a - 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. 73.3110a Section... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide (Pigment Blue 36) (CAS Reg....

  4. Speciation dependent radiotracer studies on chromium preconcentration using iron doped calcium alginate biopolymer

    International Nuclear Information System (INIS)

    The work aims to study the differential attitude of Ca-alginate (CA) and Fe-doped calcium alginate (Fe-CA) and towards Cr(III) and Cr (IV) so that, depending on the oxidation state of chromium effluent, environmentally sustainable methodologies can be prescribed for removal of chromium. Throughout the experiment 51Cr has been used as the precursor of stable chromium

  5. 40 CFR 749.68 - Hexavalent chromium-based water treatment chemicals in cooling systems.

    Science.gov (United States)

    2010-07-01

    ... Cooling Systems § 749.68 Hexavalent chromium-based water treatment chemicals in cooling systems. (a... distribution in commerce of hexavalent chromium-based water treatment chemicals for use in cooling systems. (d... holds hexavalent chromium-based water treatment chemicals for use in cooling systems. (6) Cooling...

  6. Chromium supplementation alters both glucose and lipid metabolism in feedlot cattle during the receiving period

    Science.gov (United States)

    Crossbred steers (n = 20; 235 +/- 4 kg) were fed 53 days during a receiving period to determine if supplementing chromium (Cr; KemTRACE®brandChromium Propionate 0.04%, Kemin Industries) would alter the glucose or lipid metabolism of newly received cattle. Chromium premixes were supplemented to add 0...

  7. Chromium supplementation alters the glucose and lipid metabolism of feedlot cattle during the receiving period

    Science.gov (United States)

    Crossbreed steers (n = 20; 235 ± 4 kg) were fed 53 d during a receiving period to determine if supplementing chromium (Cr; KemTRACE®brand Chromium Propionate 0.04%, Kemin Industries) would alter the glucose or lipid metabolism of newly received cattle. Chromium premixes were supplemented to add 0 (C...

  8. Soil dehydrogenase activity in the presence of chromium (III) and (VI)

    OpenAIRE

    Wolińska A.; Stępniewska Z.

    2005-01-01

    The paper presents the influence of chromium forms (III) and (VI) on the soil dehydrogenase activity. Enzyme activities can be considered effective indicators of soil quality changes resulting from environmental stress or management practices. It was found that chromium compounds have detrimental effects on soil dehydrogenase activity. After the addition of chromium, a rapid and significant decrease in enzymatic activities was observed.

  9. 40 CFR 721.981 - Substituted naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex.

    Science.gov (United States)

    2010-07-01

    ... naphthalenyl-substituted azonaphthol chromium complex. 721.981 Section 721.981 Protection of Environment...-substituted naphthalenyl-substituted azonaphthol chromium complex. (a) Chemical substance and significant new... naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex (PMN P-93-1631) is subject...

  10. 40 CFR 721.2097 - Azo chromium complex dyestuff preparation (generic name).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Azo chromium complex dyestuff... New Uses for Specific Chemical Substances § 721.2097 Azo chromium complex dyestuff preparation... substance identified generically as an azo chromium complex dyestuff preparation (PMN P-95-240) is...

  11. Hot corrosion resistance of nickel-chromium-aluminum alloys

    Science.gov (United States)

    Santoro, G. J.; Barret, C. A.

    1977-01-01

    The hot corrosion resistance of nickel-chromium-aluminum alloys was examined by cyclically oxidizing sodium sulfate-coated specimens in still air at 900, 1000, and 1100 C. The compositions tested were within the ternary region: Ni, Ni-50 at.% Cr, and Ni-50 at.% Al. At each temperature the corrosion data were statistically fitted to a third order regression equation as a function of chromium and aluminum contents. From these equations corrosion isopleths were prepared. Compositional regions with the best hot corrosion resistance were identified.

  12. 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.

  13. Electrodeposited tungsten-nickel-boron: A replacement for hexavalent chromium

    International Nuclear Information System (INIS)

    Chromium, deposited from acidic solutions of its hexavalent ion, has been the rule for wear resistant, corrosion resistant coatings for many years. Although chromium coatings are durable, the plating process generates air emissions, effluent rinse waters, and process solutions that are toxic, suspected carcinogens, and a risk to human health and the environment. Tungsten-nickel-boron (W-Ni-B) alloy deposition is a potential substitute for hexavalent chrome. It has excellent wear, corrosion, and mechanical properties and also may be less of an environmental risk. This study examines the electroplating process and deposit properties of W-Ni-B and compares them with those of hexavalent chrome

  14. The oxidation and reduction of chromium of stainless steels in an eletric arc furnace

    Directory of Open Access Journals (Sweden)

    B. Arh

    2011-07-01

    Full Text Available The oxidation of chromium during the elaboration of stainless steels occurs with oxygen in solution blown inthe melt and with oxides in the slag. A higher content of silicon in the furnace charge decreases the extent of oxidation of chromium, however, the efficient reduction of chromium from the slag is of essential importance for a minimal loss of chromium. In this survey, the theory of the oxidation of chromium, its reduction from the slag and the conditions for the formation of foaming slag are discussed.

  15. Possibility of sorption purification of chromium comprising waste waters of galvanic production by inorganic ion exchangers

    International Nuclear Information System (INIS)

    Present work is devoted to possibilities of sorption purification of chromium comprising waste waters of galvanic production by inorganic ion exchangers. Thus, the comparative study of sorption of chromium ions on anion exchanger A B-17 and on inorganic ion exchangers on the basis of hydrated titanium and zirconium dioxides in static and dynamic conditions is conducted. The influence of chromium ions concentration, solutions acidity (ph=1÷12) and presence of base electrolyte on sorption is studied. The state of chromium ions sorbed by inorganic ion exchangers is studied by means of infrared spectroscopy and spectroscopy. It is defined that inorganic sorbents could be used for chromium extraction from different solutions.

  16. Half life of chromium in serum and urine in a former plasma cutter of stainless steel

    OpenAIRE

    Petersen, R.; Thomsen, J. F.; Jorgensen, N. K.; Mikkelsen, S

    2000-01-01

    For 8 years chromium in serum and urine has been followed up in a former plasma cutter of stainless steel who was exposed to airborne dust and fumes containing chromium during this work. After the first examination for serum chromium the exposure ended. Serum chromium concentration has been measured seven times during the period and was initially very high and has subsequently dropped slowly. The half life was 40 months in serum. Urinary chromium has been measured five times. The half life wa...

  17. Reactor target from metal chromium for "pure" high-intensive artificial neutrino source

    Science.gov (United States)

    Gavrin, V. N.; Kozlova, Yu. P.; Veretenkin, E. P.; Logachev, A. V.; Logacheva, A. I.; Lednev, I. S.; Okunkova, A. A.

    2016-03-01

    The paper presents the first results of development of manufacturing technology of metallic chromium targets from highly enriched isotope 50Cr for irradiation in a high flux nuclear reactor to obtain a compact high intensity neutrino source with low content of radionuclide impurities and minimum losses of enriched isotope. The main technological stages are the hydrolysis of chromyl fluoride, the electrochemical reduction of metallic chromium, the hot isostatic pressing of chromium powder and the electrical discharge machining of chromium bars. The technological stages of hot isostatic pressing of chromium powder and of electrical discharge machining of Cr rods have been tested.

  18. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Chromium (Cr III) complex of N-ethyl-N... § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium... by weight of the chromium (Cr III) complex of heptadecylfluoro-octane sulfonic acid may be...

  19. SCIENCE AND TECHNOLOGY ACTIVITIES FOR CHROMIUM IN THE 100 AREAS

    International Nuclear Information System (INIS)

    (smbullet) Primary Objective: Protect the Columbia River - Focus is control and treatment of contamination at or near the shoreline, which is influenced by bank storage (smbullet) Secondary Objective: Reduce hexavalent chromium to 40,000 ppb), - Unknown source location(s); probably originating in reactor operation areas

  20. Intestinal absorption of chromium as affected by wheat bran

    International Nuclear Information System (INIS)

    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

  1. Differents remediation methodos for lead, chromium and cadmium contaminated soils

    International Nuclear Information System (INIS)

    The usage of phosphates in the remediation of plots contaminated with heavy metals appears to be a good strategy to lessen the danger of these metals. This study analyses the effect of the mobilization of: Lead, chromium and cadmium by utilizing diverse forms of phosphates in contaminated soils of three different origins with ph modification and without it

  2. FEATURES OF CHROMIUM DOPING OF WEAR-RESISTANT CAST IRON

    Directory of Open Access Journals (Sweden)

    V. V. Netrebko

    2015-05-01

    Full Text Available The aim of this work analysis of the influence of chromium on the process of carbide formation, changes in chemical composition of the metal substrate in the areas adjacent to the carbides and at the hardness of iron while economy nickel and manganesealloying.

  3. DANGER OF HEXAVALENT CHROMIUM AND STRATEGY FOR THE REMEDITATION

    Directory of Open Access Journals (Sweden)

    Aniruddha Roy

    2013-02-01

    Full Text Available Some metals as micronutrients have a major role in the life and growth process of plants and animals. However, certain forms of some metals may also act as toxic material even in relatively small quantities. Chromium is such a metal, whose concentration above a certain limit may cause a serious problem to the health of living organisms. Chromium (Cr may occur in several chemical forms in organic and inorganic systems. In biological systems only Cr (III and Cr (VI are significant. Among these two states, trivalent chromium (Cr-III is considered as an essential component, while hexavalent Chromium (Cr-VI in biological system has been detected as responsible for so many diseases, even some specific forms of cancer. This paper intends to present the adverse effect of Cr(VI on environment as well as on human beings and also try to find a way out to dissolve the problem by a newly developed efficient and cost effective technique.

  4. IRIS TOXICOLOGICAL REVIEW OF HEXAVALENT CHROMIUM (INTERAGENCY SCIENCE CONSULTATION DRAFT)

    Science.gov (United States)

    On Septemeber 30, 2010, the draft Toxicological Review of Hexavalent Chromium and the charge to external peer reviewers were released for external peer review and public comment. The Toxicological Review and charge were reviewed internally by EPA and by other federal agenc...

  5. Chromium toxicity to nitrifying bacteria: implications to wastewater treatment

    Science.gov (United States)

    Chromium, a heavy metal that enters wastewater treatment plants (WWTPs) through industrial discharges, can be toxic to microorganisms carrying out important processes within biological wastewater treatment systems. The effect of Cr(III) and Cr(VI) on ammonia dependent specific ox...

  6. Electrochemistry of active chromium. Part III. Effects of temperature

    Directory of Open Access Journals (Sweden)

    J. P. POPIC

    2003-11-01

    Full Text Available It was shown that the temperature in the range 20 – 65 ºC has considerable effects on the electrochemical anodic dissolution of chromium in the active potential range as well as on the electrochemical hydrogen evolution reactions on bare and oxide covered chromium surfaces. Also, the chemical dissolution of chromium is strongly affected. The apparent energy of activation for anodic dissolution is 63.1 kJ mol-1, for hydrogen evolution on a bare Cr surface 19.5 kJ mol-1, for the same reaction on an oxide covered surface 44.0 kJ mol-1 and for the chemical (“anomalous” dissolution 66.9 kJ mol-1. The temperature dependences of the total corrosion rate, and the electrochemical corrosion rate alone, are presented in polynomial forms with the appropriate constants obtained by the best fit of the experimental data. For the hydrogen evolution reaction on both bare and oxide covered chromium, the Volmer-Heyrovsky reaction mechanism with the second step as rate determining was proposed.

  7. 76 FR 8773 - Superalloy Degassed Chromium From Japan

    Science.gov (United States)

    2011-02-15

    ... applicable deadline.'' (75 FR 80457). Accordingly, pursuant to section 751(c) of the Tariff Act of 1930 (19 U... COMMISSION Superalloy Degassed Chromium From Japan AGENCY: United States International Trade Commission... Japan would be likely to lead to continuation or recurrence of material injury. On December 22,...

  8. 75 FR 67100 - Superalloy Degassed Chromium From Japan

    Science.gov (United States)

    2010-11-01

    ... superalloy degassed chromium from Japan (70 FR 76030). The Commission is conducting a review to determine..., subparts A, D, E, and F (19 CFR part 207), as most recently amended at 74 FR 2847 (January 16, 2009). \\1... rule 201.15(b)(19 CFR 201.15(b)), 73 FR 24609 (May 5, 2008). This advice was developed in...

  9. Microbial biotechnology for remediation of aquatic habitats polluted with chromium

    Directory of Open Access Journals (Sweden)

    Viorica Coşier

    2008-12-01

    Full Text Available Chromium may occur in nine different forms of oxidation ranging from ?II to +VI, with forms II, III and VI as the most commonly encountered. In Cluj county, chromium pollution dates well back in time and has caused important dysfunction to the mechanical-biological wastewater purification station of the city of Cluj (Coşier & Diţă 1996. The purpose of this study was to develop one microbial method able to reduce hexavalent chromium (mobile, permeable to cell membrane, carcinogenic and mutagenic (Ishikawa et al 1994 to the trivalent form (insoluble and an essential element for humans (Song et al 2006. Different sources of chromium-reducing bacteria and many sources of carbon and energy added to the Kvasnikov mineral basal medium (Komori et al 1990 with increasing amount of chromate (200- 1000 mg/l were tested. Two bacterial strains, able to reduce even 1000 mg chromate/l, were isolated in pure culture. For one of these bacterial strains, we determined the optimum conditions for the reduction of Cr (VI.

  10. Developing of chromium cast steel on sleeves of heavy machines

    Directory of Open Access Journals (Sweden)

    J. Kilarski

    2010-10-01

    Full Text Available The results of investigations of hardness, impact resistance, abrasive and corrosive wear of selected chromium cast steel with destination on sleeves of heavy machines were introduced in the article. First results of exploational investigations talked over on the end.

  11. Production performance of quails given chromium organic in ration

    Directory of Open Access Journals (Sweden)

    Deden Sudrajat

    2014-12-01

    Full Text Available Egg production of quails depends on quality of ration. Nutrient manipulation by chromiun inclusion in ration is a possible way to improve production. It is known that chromium mineral in form of GTF in blood has a role not only in enhancement of glucose entering cells through improvement of insulin activity but also in metabolism of lipid and synthesis of protein and elimination of heat stress to improve egg production. This study aimed at assessing egg production of quails fed ration containing chromium-yeast. Sixty-four quails aged 40 days were used. A completely randomized design with 4 treatments and 4 replication was applied in this study. Treatment consisted of commercial ration + Cr 0 ppm (R1, commercial ration + Cr 0.5 ppm (R2, commercial ration + Cr 1 ppm (R3, and commercial ration+ Cr 1.5 ppm (R4. Measurements were taken on feed intake, egg weight, egg mass production, hen day, feed conversion rate, egg index, and egg shell thickness. Results showed that A ration containing organic chromium as much as 1,5 ppm did not affect feed intake, egg production, egg weight, and eggshell thickness, however lowered feed conversion rate by up to 32.25% from that of control. Supplementation of 0,5 ppm chromium in the ration lowered the value of eggs index in the fourth week.

  12. Discovery of Chromium, Manganese, Nickel, and Copper Isotopes

    OpenAIRE

    Garofali, K.; Robinson, R; Thoennessen, M

    2010-01-01

    Twenty-seven chromium, twenty-five manganese, thirty-one nickel and twenty-six copper isotopes have so far been observed and the discovery of these isotopes is discussed. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  13. Invariant coefficients of diffusion in iron-chromium-nickel system

    Energy Technology Data Exchange (ETDEWEB)

    Mokrov, A.P.; Akimov, V.K.; Golubev, V.G.

    1984-02-01

    The temperature and concentration dependences of the Dsub(c) coefficients in the ..gamma..-phase of iron-chromium-nickel system are determined. It is proposed to described mutual diffusion in multicomponent systems using invariant, i.e. independent of the choice of solvent, coefficients of diffusion. The assumption that their temperature dependence follows the Arrhenius law is confirmed by the experiment.

  14. Invariant coefficients of diffusion in iron-chromium-nickel system

    International Nuclear Information System (INIS)

    The temperature and concentration dependences of the Dsub(c) coefficients in the γ-phase of iron-chromium-nickel system are determined. It is proposed to described mutual diffusion in mul-- ticomponent systems using invariant, i. e. independent of the choice of solvent, coefficients of diffusion. The assumption that their temperature dependence follows the Arrhenius law is confirmed by the experiment

  15. Friction and wear behavior of chromium carbide coatings

    International Nuclear Information System (INIS)

    Chromium carbides, tungsten carbide, and chromium oxide have been tested and evaluated as coatings to protect high-temperature gas-cooled reactor (HTGR) steam generator and other HTGR components from adhesion, galling associated with sliding wear or from fretting. Tests were performed in commercially-pure helium and in helium doped with various gaseous impurities (H2, H2O, CH4, CO) to simulate the primary coolant of an HTGR. Several types of chromium carbide coatings including Cr3C2, Cr7C3, and Cr23C6, were tested for wear resistance and resistance to long-term spalling. Tungsten carbide and chromium oxide coatings were tested in sliding wear tests. Cr23C6-NiCr coatings showed the best performance (from 400 to 8160C) whether they were applied by detonation gun or plasma gun spraying methods. The presence of the Cr23C6-NiCr coatings did not affect the creep rupture properties of Alloy 800H substrates at temperatures up to 7600C. Low-cycle fatigue life of similar specimens at 5930C was reduced to 10 to 20% when tested in the 1 to 0.6% strain range

  16. Porosity of detonation coatings on the base of chromium carbide

    International Nuclear Information System (INIS)

    Porosity of detonation coatings on the base of chromium carbide is estimated by the hydrostatic weighing. The open porosity value dependence on the distance of spraying, depth of the charge, ratio and volume of the detonator barrie filing with gas components is established. Pore distribution in the cross section of a specimen tested for porosity is studied by the methods of metallographic analysis

  17. Structure and morphology studies of chromium film at elevated temperature in hypersonic environment

    Indian Academy of Sciences (India)

    G M Hegde; V Kulkarni; M Nagaboopathy; K P J Reddy

    2012-06-01

    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. Surface morphology changes of chromium coating have been studied using scanning electron microscopy (SEM) before and after shock heating. Significant amount of chromium ablation and sublimation from the model surface is noticed from SEM micrographs. Traces of randomly oriented chromium oxides formed along the coated surface confirm surface reaction of chromium with oxygen present behind the shock. Large traces of amorphous chromium oxide phases are also observed.

  18. Contribution of photoelectron spectrometry and infrared spectrometry to the study of various oxidised forms of chromium

    International Nuclear Information System (INIS)

    Securate knowledge of internal surface of primary coolant circuits of PWR is required for an estimation of dissolution of used materials and for estimation of decontamination efficiency. The binding energies of various electron levels of chromium were determined by photoelectron spectrometry (ESCA), both for the metal and for certain compounds. Because of the intensities of the signals obtained the 2 p 3/2 level alone can be used for analytical purposes. Owing to a possible interference between this level due to hexavalent chromium and a satellite peak caused by trivalent chromium the method is not able to show up small amounts of chromium VI in chromium III. Simultaneous detection of the hexavalent and trivalent forms was achieved by infrared spectrometry. The problem of revealing traces of chromium VI in surface layers of trivalent chromium oxide has thus been solved

  19. 10 CFR 55.57 - Renewal of licenses.

    Science.gov (United States)

    2010-01-01

    ... Administrator specified in § 55.5(b). (3) Provide written evidence of the applicant's experience under the... 10 Energy 2 2010-01-01 2010-01-01 false Renewal of licenses. 55.57 Section 55.57 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) OPERATORS' LICENSES Licenses § 55.57 Renewal of licenses. (a) The...

  20. Dreamweaver CS55 The Missing Manual

    CERN Document Server

    McFarland, David

    2011-01-01

    Dreamweaver is the tool most widely used for designing and managing professional-looking websites, but it's a complex program. That's where Dreamweaver CS5.5: The Missing Manual comes in. With its jargon-free explanations, 13 hands-on tutorials, and savvy advice from Dreamweaver expert Dave McFarland, you'll master this versatile program with ease. Get A to Z guidance. Go from building your first web page to creating interactive, database-driven sites.Build skills as you learn. Apply your knowledge through tutorials and downloadable practice files.Create a state-of-the-art website. Use powerf

  1. Division XII: Commission 55: Communicating Astronomy with the Public

    Science.gov (United States)

    Christensen, Lars Lindberg; Russo, Pedro; Robson, Ian; Arcand, Kimberly Kowal; Fienberg, Richard Tresch; Ödman-Govender, Carolina; Sekiguchi, Kazuhiro; Wheeler, Pete; Zhu, Jin

    2015-08-01

    A good fraction of the Commission 55 (C55) Organizing Committee met in Beijing in August at the XXVIII IAU General Assembly, where C55 organized Special Session 14 (SpS14) entitled ``Communicating Astronomy with the Public for Scientists.'' During our C55 business meeting, and again during an impromptu gathering a few days later, we discussed changes in the IAU's organizational and programmatic structure and how these changes might affect C55. This report summarizes key points and offers some ideas about what we're calling ``C55 v2.0.'' For background and reference, see the C55 website at http://www.communicatingastronomy.org.

  2. Laboratory scale studies on removal of chromium from industrial wastes

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Chromium being one of the major toxic pollutants is discharged from electroplating and chrome tanning processes and is also found in the effluents of dyes, paint pigments, manufacturing units etc. Chromium exists in aqueous systems in both trivalent (Cr 3+) and hexavalent (Cr 6+) forms. The hexavalent form is carcinogenic and toxic to aquatic life, whereas Cr3+ is however comparatively less toxic. This study was undertaken to investigate the total chromium removal from industrial effluents by chemical means in order to achieve the Pakistan NEQS level of 1 mg/L by the methods of reduction and precipitation. The study was conducted in four phases.In phase I, the optimum pH and cost effective reducing agent among the four popular commercial chemicals was selected. As a result, pH of 2 was found to be most suitable and sodium meta bisulfate was found to be the most cost effective reducing agent respectively. Phase II showed that lower dose of sodium meta bisulfate was sufficient to obtain 100 % efficiency in reducing Cr6+ to Cr3+, and it was noted that reaction time had no significance in the whole process. A design curve for reduction process was established which can act as a tool for treatment of industrial effluents.Phase III studies indicated the best pH was 8.5 for precipitation of Cr 3+ to chromium hydroxide by using lime. An efficiency of 100 % was achievable and a settling time of 30 minutes produced clear effluent. Finally in Phase IV actual waste samples from chrome tanning and electroplating industries, when precipitated at pH of 12 gave 100 % efficiency at a settling time of 30 minutes and confirmed that chemical means of reduction and precipitation is a feasible and viable solution for treating chromium wastes from industries.

  3. Sorption of chromium in soils of the Cerrado Goias, Brazil

    Directory of Open Access Journals (Sweden)

    Welershon José de Castro

    2010-08-01

    Full Text Available Land application of tannery sludge, which usually contain high levels of chromium, and considerable amounts of organic matter, macronutrients and micronutrients may contribute to the improvement of soil fertility and plant nutrition, and constitutes a form of disposal residue in the environment. The objective of this work was to determine the sorption isotherms of metal chromium (Cr+3 in a Ultisol, Oxisol Typic Acrustox, Quartzipsamment and Kandic Oxisol, identify soil classes that are prone to chromium mobility, and characterize the potential of agricultural soils of Goiás that are subject to groundwater contamination by the potentially toxic metal. For the establishment of sorption isotherms, solutions were prepared at 1:10 in volume. Air dried samples of 5.0 cm3 of each class of soil were placed in triplicates in beakers of 250.0 cm3. A solution containing 50.0 cm3 of the potentially toxic metal was added to solution. The solutions were prepared in CaCl2.(2H2O (0.01 mol.L-1 as electrolyte support and employing the basic chromium sulphate as a source of metal. Adjustments were made to the polynomial regression between the concentrations of potentially toxic levels of metal contaminants in the solution depending on the concentration of metal in the filtered solution after equilibrium. The Quartzipsamment showed lower retention compared to other classes of soils. Therefore it is more vulnerable to groundwater contamination if industrial wastes containing trivalent chromium are used as fertilizer.

  4. Raman spectroscopy of supported chromium oxide catalysts : determination of chromium-oxygen bond distances and bond orders

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Wachs, I.E.

    1996-01-01

    An empirical correlation is described for relating Raman stretching frequencies of chromium—oxygen (Cr—O) bonds to their bond lengths in chromium oxide reference compounds. An exponential fit of crystallographically determined Cr—O bond lengths to Cr—O Raman symmetric stretching frequencies (800–130

  5. 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...

  6. The effect of dietary supplementation with different forms and levels of organic chromium on broilers meat quality

    OpenAIRE

    Keleman Svetlana P.; Kevrešan Slavko E.; Supić Boriša; Perić Lidija; Strugar Vladimir

    2006-01-01

    This paper deals with the effect of supplementation with the three different preparations of organic chromium complexes: the ethylenediaminetetraacetic acid complex with chromium; chromium (III)­lysine and chromium picolinate, on broilers meat quality. In every preparation supplementing broilers diet chromium was present at the three different levels: 0.2; 0.4 and 0.6 mg/kg. The meat quality was monitored with respect to the following parameters: the contents of fat, protein, minerals and wat...

  7. Chromium, chromium isotopes and selected trace elements, western Mojave Desert, USA

    Science.gov (United States)

    Izbicki, J.A.; Ball, J.W.; Bullen, T.D.; Sutley, S.J.

    2008-01-01

    Chromium(VI) concentrations in excess of the California Maximum Contaminant Level (MCL) of 50 ??g/L occur naturally in alkaline, oxic ground-water in alluvial aquifers in the western Mojave Desert, southern California. The highest concentrations were measured in aquifers eroded from mafic rock, but Cr(VI) as high as 27 ??g/L was measured in aquifers eroded from granitic rock. Chromium(VI) concentrations did not exceed 5 ??g/L at pH < 7.5 regardless of geology. ??53Cr values in native ground-water ranged from 0.7 to 5.1??? and values were fractionated relative to the average ??53Cr composition of 0??? in the earth's crust. Positive ??53Cr values of 1.2 and 2.3??? were measured in ground-water recharge areas having low Cr concentrations, consistent with the addition of Cr(VI) that was fractionated on mineral surfaces prior to entering solution. ??53Cr values, although variable, did not consistently increase or decrease with increasing Cr concentrations as ground-water flowed down gradient through more oxic portions of the aquifer. However, increasing ??53Cr values were observed as dissolved O2 concentrations decreased, and Cr(VI) was reduced to Cr(III), and subsequently removed from solution. As a result, the highest ??53Cr values were measured in water from deep wells, and wells in discharge areas near dry lakes at the downgradient end of long flow paths through alluvial aquifers. ??53Cr values at an industrial site overlying mafic alluvium having high natural background Cr(VI) concentrations ranged from -0.1 to 3.2???. Near zero ??53Cr values at the site were the result of anthropogenic Cr. However, mixing with native ground-water and fractionation of Cr within the plume increased ??53Cr values at the site. Although ??53Cr was not necessarily diagnostic of anthropogenic Cr, it was possible to identify the extent of anthropogenic Cr at the site on the basis of the ??53Cr values in conjunction with major-ion data, and the ??18O and ??D composition of water from wells.

  8. Accident selection methodology for TA-55 FSAR

    International Nuclear Information System (INIS)

    In the past, the selection of representative accidents for refined analysis from the numerous scenarios identified in hazards analyses (HAs) has involved significant judgment and has been difficult to defend. As part of upgrading the Final Safety Analysis Report (FSAR) for the TA-55 plutonium facility at the Los Alamos National Laboratory, an accident selection process was developed that is mostly mechanical and reproducible in nature and fulfills the requirements of the Department of Energy (DOE) Standard 3009 and DOE Order 5480.23. Among the objectives specified by this guidance are the requirements that accident screening (1) consider accidents during normal and abnormal operating conditions, (2) consider both design basis and beyond design basis accidents, (3) characterize accidents by category (operational, natural phenomena, etc.) and by type (spill, explosion, fire, etc.), and (4) identify accidents that bound all foreseeable accident types. The accident selection process described here in the context of the TA-55 FSAR is applicable to all types of DOE facilities

  9. 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.

  10. Bioadsorption and bioaccumulation of chromium trivalent in Cr(III)-tolerant microalgae: a mechanisms for chromium resistance.

    Science.gov (United States)

    Pereira, M; Bartolomé, M C; Sánchez-Fortún, S

    2013-10-01

    Anthropogenic activity constantly releases heavy metals into the environment. The heavy metal chromium has a wide industrial use and exists in two stable oxidation states: trivalent and hexavalent. While hexavalent chromium uptake in plant cells has been reported that an active process by carrying essential anions, the cation Cr(III) appears to be taken up inactively. Dictyosphaerium chlorelloides (Dc1M), an unicellular green alga is a well-studied cell biological model organism. The present study was carried out to investigate the toxic effect of chromium exposures on wild-type Cr(III)-sensitive (Dc1M(wt)) and Cr(III)-tolerant (Dc1M(Cr(III)R30)) strains of these green algae, and to determine the potential mechanism of chromium resistance. Using cell growth as endpoint to determine Cr(III)-sensitivity, the IC₅₀(₇₂) values obtained show significant differences of sensitivity between wild type and Cr(III)-tolerant cells. Scanning electron microscopy (SEM) showed significant morphological differences between both strains, such as decrease in cell size or reducing the coefficient of form; and transmission electron microscopy (TEM) revealed ultrastructural changes such as increased vacuolization and cell wall thickening in the Cr(III)-tolerant strain with respect to the wild-type strain. Energy dispersive X-ray analysis (SEM/XEDS) revealed that Cr(III)-tolerant D. chlorelloides cells are able to accumulate considerable amounts of chromium distributed in cell wall (bioadsorption) as well as in cytoplasm, vacuoles, and chloroplast (bio-accumulation). Morphological changes of Cr(III)-tolerant D. chlorelloides cells and the presence of these electron-dense bodies in their cell structures can be understood as a Cr(III) detoxification mechanism. PMID:23810518

  11. Influence of Age, Gender and Duration of Diabetes on Serum and Urine Levels of Zinc, Magnesium, Seleniumand Chromium in Type 2 Diabetics in Calabar, Nigeria

    Directory of Open Access Journals (Sweden)

    Augusta Chinyere Nsonwu

    2006-09-01

    Full Text Available The study aimed to demonstrate the possible effect of some variables such as age,gender and duration of diabetes on the serum and urine levels of zinc, magnesium,selenium and chromium in type 2 diabetic subjects and a control group of nondiabetic individuals. Serum and urine zinc (Zn, magnesium (Mg, selenium (Se, chromium (Cr and creatinine; fasting plasma glucose (FPG and serum urea levelswere determined in 60 diabetic subjects of both genders aged between 40-75 years and 40 age matched non diabetic subjects from Calabar, Nigeria using colorimetric methods and atomic absorption spectrophotometry (AAS. Elderly diabetics (55-75 have significantly (p<0.05 lower serum Se and Cr and higher urinary traceelements than the younger age group (40-54. Female diabetics have significantly (p<0.05 higher serum Zn and Se and lower urinary Mg and Zn than diabetic males. Serum and urine trace elements concentrations varied significantly (p<0.05 with the duration of diabetes. Aging and increasing duration of diabetes alters the metabolism of Zinc, Magnesium, Selenium and Chromium by decreasing their serum concentration and increasing their urinary excretion. The gender related differences in trace element levels in diabetics, might be attributed to hormonal imbalance associated with the diabetic state.

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

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

    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 〈 1 month of the restoration duration, among which higher Ni excretions were found in those with either a higher number of teeth replaced by 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 〈1, 1 to 〈3 and 3 to 〈6 months, especially in those with a higher 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.

  13. A Study of the High Temperature on Chromium Carbide

    International Nuclear Information System (INIS)

    The oxidation rates of chromium carbide have been measured at 900 to 1300 .deg. C and oxygen pressures between 2x10-2 8 x 10-2 Pa using thermogravimetric analysis method. Oxidation behavior of chromium carbide appeared to change very sensitively with both temperature and oxygen pressure. In case with the oxygen pressure lower than 8 x 10-2 Pa, the weight gain in the specimen due to the formation of chromium oxide occurred linearly with time at the every temperature studied, but when the oxygen pressure was increased up to 8 x 10-2Pa, the weight gain behavior versus time showed entirely different tendency. That is, in the temperature range of 900 .deg. C to 1000 .deg. C weight gain occurred, however in the range of 1000 .deg. C to 1300 .deg. C weight lost was observed. The reason for the observed linear kinetics could be inferred as follows. As the oxidation of carbide proceeded carbon monoxide would build up at the interface of the chromium oxide and carbide. If the equilibrium pressure of carbon monoxide at the interface exceeds the gas pressure at the outer specimen surface, the oxide scale formed on it might be cracked exposing new carbide sites on which oxidation could occur successively. Through a thermodynamic consideration it was judged that the above deduction was reasonable. On the other hand, the weight lost mentioned above was explained that it could occur mainly due to the further oxidation of Cr2O3 to the volatile CrO3 at the corresponding experimental conditions. Weight loss phenomenon mentioned before which was observed in the oxidation of chromium carbide was also clearified by X-ray diffraction method and SEM. That is, at 900 .deg. C stable oxide of chromium, (Cr2O3) was identified easily on the specimen surface. However, at 1300 .deg. C, only a few amount of this stable oxide could be found on to specimen surface, indicating Cr2O3 had been evaporated to CrO3 gas

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

    Energy Technology Data Exchange (ETDEWEB)

    Survilienė, S., E-mail: sveta@ktl.mii.lt; 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.

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

    International Nuclear Information System (INIS)

    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

  16. Bionanocomposites based on layered silicates and cationic starch as eco-friendly adsorbents for hexavalent chromium removal.

    Science.gov (United States)

    Koriche, Yamina; Darder, Margarita; Aranda, Pilar; Semsari, Saida; Ruiz-Hitzky, Eduardo

    2014-07-21

    Functional bionanocomposites based on two layered silicates, the commercial montmorillonite known as Cloisite®Na and a natural bentonite from Algeria, were prepared by intercalation of cationic starch, synthesized with two different degrees of substitution, 0.85 and 0.55. After characterization of the prepared bionanocomposites by XRD and zeta potential measurements, batch studies were conducted to evaluate the adsorption capacity of hexavalent chromium anions from aqueous solution. The adsorption isotherms, adsorption kinetics, and the effect of pH on the process were studied. The removal efficiency was evaluated in the presence of competing anions such as NO3(-), ClO4(-), SO4(2-) and Cl(-). In order to regenerate the adsorbent for its repeated use, the regeneration process was studied in two different extractant solutions, 0.1 M NaCl at pH 10 and 0.28 M Na2CO3 at pH 12. PMID:24658793

  17. Internal Friction In The PFN Ceramics With Chromium Dopand

    OpenAIRE

    Zachariasz R.; Bochenek D.; Bruś B.

    2015-01-01

    An aim of this work was to determine an influence of an admixture, the chromium (for x from 0.01 to 0.06), on the mechanical properties of the PFN ceramics. The ceramics with chemical composition Pb(Fe0.5−xCrxNb0.5)O3 was synthesized in two steps from simple oxides PbO, Fe2O3, Nb2O5, Cr2O3. The first stage was based on obtaining the FeNbO4 from the Fe2O3 and Nb2O5 simple oxides. At this stage an admixture in a form the Cr2O3 chromium oxide was added to the solution. In the second stage the Pb...

  18. Hexavalent chromium effects on carbon assimilation in Selenastrum capricornutum

    International Nuclear Information System (INIS)

    One of the difficulties in assessing toxic substances such as metals and complex organic compounds is the duration of the necessary tests. It would be beneficial to have available standardized tests of short duration that would allow a reduction in necessary manpower and overall cost as well as provide a method to evaluate chemicals that are readily degraded (i.e., within a few hours). One method available is the short-term photosynthesis response of algae to a given toxicant. Photosynthesis is not only a critical physiological response but is also one for which standard, accurate methods are available. The 14C method has been used to study the effects of chromium on algae. More recently, it was proposed that the 14C method be used to measure short-term photosynthetic response as a standard algal bioassay. The present study was designed to further evaluate, via photosynthetic response, the potential effects of hexavalent chromium on Selenastrum capricornutum

  19. How to Bypass Verified Boot Security in Chromium OS

    CERN Document Server

    Husain, Mohammad Iftekhar; Qiao, Chunming; Sridhar, Ramalingam

    2012-01-01

    Verified boot is an interesting feature of Chromium OS that should detect any modification in the firmware, kernel or the root file system (rootfs) by a dedicated adversary. However, by exploiting a design flaw in verified boot, we show that an adversary can replace the original rootfs by a malicious rootfs containing exploits such as a spyware and still pass the verified boot process. The exploit is based on the fact that although a kernel partition is paired with a rootfs, verification of kernel partition and rootfs are independent of each other. We experimentally demonstrate an attack using both the base and developer version of Chromium OS in which the adversary installs a spyware in the target system to send cached user data to the attacker machine in plain text which are otherwise inaccessible in encrypted form. We also discuss possible directions to mitigate the vulnerability.

  20. Statistical screening of hexavalent chromium biosorption by Sargassum

    Directory of Open Access Journals (Sweden)

    Abbas Rezaee

    2014-01-01

    Full Text Available The aim of this study was to investigate the statistical screening of hexavalent chromium, Cr (VI, from an aqueous solution using brown seaweed Sargassum as a biosorbent. The biosorption process conditions were evaluated with the statistical screening followed by Plackett-Burman design. The effect of solution pH, contact time, initial chromium and nitrate concentrations were studied. The experimental data were fitted to the Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. Plackett-Burman design showed the contact time and pH are the most important parameters influencing the Cr (VI biosorption onto Sargassum. The optimum pH, contact time, the initial biosorbent dosage and initial Cr (VI and nitrate concentration were found to be 3, 120 min, 1.3 g, 50 mg/L and 1000 mg/L, respectively. The results indicated that the Freundlich model was the most suitable for Cr (VI biosorption onto Sargassum.

  1. Intragranular Chromium Nitride Precipitates in Duplex and Superduplex Stainless Steel

    OpenAIRE

    Iversen, Torunn Hjulstad

    2012-01-01

    Intragranular chromium nitrides is a phenomenon with detrimental effects on material properties in superduplex stainless steels which have not received much attention. Precipitation of nitrides occurs when the ferritic phase becomes supersaturated with nitrogen and there is insufficient time during cooling for diffusion of nitrogen into austenite. Heat treatment was carried out at between 1060◦C and 1160◦C to study the materials susceptibility to nitride precipitation with...

  2. Identification Trial of Crystallization Parameters of Modified Chromium Cast Iron

    OpenAIRE

    A. Studnicki

    2007-01-01

    In the paper results of researches of abrasion-resisting chromium cast iron inoculated with boron carbide B4C primary crystallization are presented. The main aim of work was make an attempt to identification of crystallization parameters that changed in reason of inoculation. Essential primary crystallization parameters, with the help of which, will be possible to evaluate the inoculation capacity were searched. It was found that in the result of inoculant actions characteristic temperatures ...

  3. Fabrication and characterisation of uranium, molybdenum, chromium, niobium and aluminium

    International Nuclear Information System (INIS)

    This paper describes fabrication of binary uranium alloys by melting and casting. The following alloys with nominal composition were obtained by melting in the vacuum furnace: uranium with niobium contents from 0.5%- 4.0% and uranium with molybdenum contents from 0.4% - 1.2%. Uranium alloys with chromium content from 0.4% - 1.2% and uranium alloy with 0.12% of aluminium were obtained by vacuum induction furnace (electric arc melting)

  4. Recovery of Chromium from Waste Taning Liquors by Magnesium Oxide

    Directory of Open Access Journals (Sweden)

    Mahmood M. Barbooti

    2010-10-01

    Full Text Available This is a case study of AL-Za’afaraniya tanning factory, 15 km to the south of Baghdad, to spot light on simple chemical treatment of the discharged water to solve the environmental problems associated with its chromium content management. The treatment was extended to the recovery and reuse of chromium. Chromium was precipitated by the addition of magnesium oxide which also aid as a neutralizer for the acidic effluent. The laboratory treatment was carried out to find the optimum conditions. The wastewater samples were taken from the outline area of the tannery. Box-Wilson method was adopted to find useful relationships between the operating variables (temperature, mixing period and magnesium oxide dose and the pH and chromium content of effluent. The experimental data were successfully fitted to second order polynomial mathematical models for the treatment. The most favorable operating conditions for the treatment were: temperature, 30 ºC; mixing period, 50 min and magnesium oxide concentration, 3000 mg/L. On using the optimum conditions a mathematical model simulating the operation for the treatment was obtained as follows:Cr = 6.0848 – 0.001839 X11 – 0.105334 X12 – 0.041038 X13pH = 10.29086 – 0.001223 X11 – 0.140043 X12 – 0.00953 X13Experimentally Cr concentration was decreased to about (0.5 mg/L in wastewater after raising the pH value to (7.35 by adding magnesium oxide.

  5. Analysis of chromium behaviour and speciation during the electrodialytic process

    OpenAIRE

    Gonçalves, Ana Rita Sarmento

    2015-01-01

    The interest in chromium (Cr) arises from the widespread use of this heavy metal in various industrial processes that cause its release as liquid, solid and gaseous waste into the environment. The impact of Cr on the environment and living organisms primarily depends on its chemical form, since Cr(III) is an essential micronutrient for humans, other animals and plants, and Cr(VI) is highly toxic and a known human carcinogen. This study aimed to evaluate if the electrodialytic process (ED) ...

  6. Soils contaminated with hexavalent chromium : sorption, migration and remediation

    OpenAIRE

    Fonseca, Bruna

    2011-01-01

    The interest in environmental soil science has been growing in the last years due to the continuous degradation of this major natural resource. In this work, a representative sample of a typical loamy sand soil was collected in Porto, Portugal, in a zone of intensive agriculture activity. This soil was used for a series of tests concerning the adsorption, transport and fate of hexavalent chromium. The adsorption equilibrium and sorption kinetics were evaluated through the fitting of several m...

  7. Bioleaching of hexavalent chromium from soils using acidithiobacillus thiooxidans

    OpenAIRE

    Fonseca, Bruna; Rodrigues, Joana; Queiroz, A.M.; Tavares, Teresa

    2010-01-01

    The continuous and growing degradation of the environment, due to several anthropogenic activities, is a main concern of the scientific community. Consequently, the development of low cost techniques to clean air, water and soils are under intense investigation. In this study, the focused problem is the soil contamination by hexavalent chromium, which is known for its several industrial applications - production of stainless steel, textile dyes, wood preservation and leather tanning - its hig...

  8. Biosorption of Hexavalent Chromium from Aqueous Medium with Opuntia Biomass

    OpenAIRE

    José A. Fernández-López; Angosto, José M.; María D. Avilés

    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 ...

  9. Low energy magnetic fluctuations in the TSDW phase of chromium

    Energy Technology Data Exchange (ETDEWEB)

    Azuah, R.T. [Hahn-Meitner Inst., Berlin (Germany); Kulda, J. [Inst. Laue Langevin, Grenoble (France); Pynn, R. [Los Alamos National Lab., NM (United States); Stirling, W.G. [Univ. of Liverpool (United Kingdom). Dept. of Physics

    1997-12-01

    A polarized neutron study of chromium carried out in a field of 6T applied to a single-domain single-Q crystal indicates that the inelastic intensity observed close to the transverse spin density wave (TSDW) satellite positions (1 {+-} {delta}, 0,0) does not behave as expected for spin-wave scattering. In particular, the signal corresponds to magnetization fluctuations of almost equal magnitude both parallel and perpendicular to the ordered moments in the TSDW phase.

  10. Characterisation of chromium nitride films produced by PVD techniques

    OpenAIRE

    Barata, A.; CUNHA L.; Moura, C.

    2001-01-01

    Chromium nitride thin films have been deposited on stainless steel substrates by r.f. reactive magnetron sputtering. The influence of process parameters such as substrate bias and partial pressure of reactive gas have been investigated. The characterisation of the coatings was performed by X-ray diffraction (XRD), Raman Spectroscopy (RS) and nano-indentation experiments. These studies allow to analyse the influence of deposition parameters in crystal phases, crystal orientationytextu...

  11. Chromium speciation in solid matrices and regulation: a review.

    Science.gov (United States)

    Unceta, N; Séby, F; Malherbe, J; Donard, O F X

    2010-06-01

    In recent years, the extensive use of chromium in industrial processes has led to the promotion of several directives and recommendations by the European Union, that try to limit and regulate the presence of Cr(VI) in the environment and to protect industrial workers using chromium and end-users of manufactured products. As a consequence, new standard methods and analytical procedures have been published at the EU level for Cr(VI) determination in soil, sludge, sediment, and similar waste materials, workplace atmospheres, cement, packaging materials, industrially produced samples, and corrosion-protection layers on some components of vehicles and electrical and electronic equipment. The objective of this article is to summarize the different directives and recommendations and to critically review the currently existing standard methods and the methods published in the literature for chromium speciation in the above mentioned solid matrices, putting the emphasis on the different extraction procedures which have been developed for each matrix. Particular attention has been paid to Cr(III) and Cr(VI) inter-conversions that can occur during extraction and efforts to minimize these unwanted reactions. Although the use of NaOH-Na(2)CO(3) solutions with hot plate extraction seems to be the more widespread procedure, species transformation can still occur and several studies suggest that speciated isotope-dilution mass spectrometry (SIDMS) could be a suitable tool for correction of these interconversions. Besides, recent studies have proved the role of Cr(III) in chromium toxicology. As a consequence, the authors suggest an update of standard methods in the near future. PMID:20099060

  12. Study of Chromium Oxide Activities in EAF Slags

    Science.gov (United States)

    Yan, Baijun; Li, Fan; Wang, Hui; Sichen, Du

    2016-02-01

    The activity coefficients of chromium in Cu-Cr melts were determined by equilibrating liquid copper with solid Cr2O3 in CO-CO2 atmosphere. The temperature dependence of the activity coefficients of chromium in Cu-Cr melts could be expressed as lg γ_{Cr}(s)^{0} = { 3 2 5 9( ± 1 8 6} )/T - 0. 5 9( { ± 0. 1} ). Based on the above results, the activities of bivalent and trivalent chromium oxide in some slags at 1873 K (1600 °C) were measured. The slags were equilibrated with Cu-Cr melts under two oxygen partial pressures ( {p_{O}_{ 2} }} } = 6.9 × 10-4 and 1.8 × 10-6 Pa, respectively). The morphology of the quenched slags and the solubility of chromium oxide in the melts were investigated by EPMA, SEM, and XRD. Under both oxygen partial pressures, the slags were saturated by the solid solution MgAl2- x Cr x O4- δ . At the low oxygen partial pressure (1.8 × 10-6 Pa), the content of Cr in the liquid phase varied from 0.4 to 1.6 mass pct with the total Cr content in the slags increasing from 1.3 to 10.8 mass pct. At the high oxygen partial pressure (6.9 × 10-4 Pa), the content of Cr in the liquid phase decreased to the level of 0.2 to 0.6 mass pct. Both the activities of CrO and Cr2O3 in slag were found to increase approximately linearly with the increase of the total Cr content in slag. While the oxygen partial pressure had minor effect on the activity of Cr2O3 in the slag, it had significant effect on the activity of CrO.

  13. Fretting damage of high carbon chromium bearing steel

    OpenAIRE

    Kuno, Masato

    1988-01-01

    This thesis consists of four sections, the fretting wear properties of high carbon chromium bearing steel; the effect of debris during fretting wear; an introduction of a new fretting wear test apparatus used in this study; and the effects of fretting damage parameters on rolling bearings. The tests were operated under unlubricated conditions. Using a crossed cylinder contact arrangement, the tests were carried out with the normal load of 3N, slip amplitude of 50µm, and frequency of 30Hz ...

  14. Cytokine detection for the diagnosis of chromium allergy *

    OpenAIRE

    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,...

  15. Chromium propionate enhances adipogenic differentiation of bovine intramuscular adipocytes

    OpenAIRE

    Rebecca eTokach; Flavio eRibeiro; Ki Yong eChung; Whitney eRounds; Johnson, Bradley J.

    2015-01-01

    In vitro experiments were performed to determine the effects of increasing concentrations of chromium propionate on mRNA and protein abundance of different enzymes and receptors. Intramuscular and subcutaneous preadipocytes and bovine satellite cells were isolated from the longissimus muscle to determine the effect of treatment on glucose transporter type 4 (GLUT4) and peroxisome proliferator-activated receptor γ mRNA and GLUT4 protein abundance. Preadipocyte cultures were treated with diffe...

  16. Chromium Propionate Enhances Adipogenic Differentiation of Bovine Intramuscular Adipocytes

    OpenAIRE

    Tokach, Rebecca J.; Ribeiro, Flavio R. B.; Chung, Ki Yong; Rounds, Whitney; Johnson, Bradley J.

    2015-01-01

    In vitro experiments were performed to determine the effects of increasing concentrations of chromium propionate (CrPro) on mRNA and protein abundance of different enzymes and receptors. Intramuscular (IM) and subcutaneous (SC) preadipocytes and bovine satellite cells were isolated from the longissimus muscle to determine the effect of treatment on glucose transporter type 4 (GLUT4) and peroxisome proliferator-activated receptor γ mRNA and GLUT4 protein abundance. Preadipocyte cultures were t...

  17. The behaviour of chromium in aquatic and terrestrial food chains

    International Nuclear Information System (INIS)

    Chromium has been considered both as potential radioactive and conventional pollutant. Chromium-51 is produced by the activation of 50Cr, which may be present either as a component of steel alloys used in reactors, or in Na2CrO4 added as an anticorrosion agent to the cooling water. Only small amounts of 51Cr are normally found in the liquid waste of nuclear power plants before discharge into rivers. In exceptional situations, however, as a result of the direct release of cooling waters, the aquatic environments may receive relatively large quantities of 51Cr. Part of this 51Cr is adsorbed e.g. to the sediments, but a fraction remains in solution in the river water. Somme accumulation of the radionuclide is observed in fresh water and marine organisms. Therefore, although 51Cr has a relatively short physical half life (27.8d), it is of interest to acquire better information on its accumulation by different species of fresh water organisms and plants, as well as on its behaviour in soils, in order to evaluate the relative importance of this nuclide in the radioactive contamination of the aquatic and terrestrial food chains. As a related and sometimes associated pollutant, stable chromium is also taken into consideration. This element occurs fairly frequently as an environmental pollutant in many countries, either because of its abundance in soils derived from serpentine or because of its release to the environment from industrial wastes. The sequence of presentation of the experiment data is based on the consecutive steps of the contamination process: aquatic environment, soils, plant link of the food chain. Special attention is paid, in the different chapters, to the behaviour of various chemical forms of chromium and to their distribution in different fractions: soluble in water, adsorbed, precipitated on particles or complexed with organic material

  18. Plasma source ion implantation of ammonia into electroplated chromium

    International Nuclear Information System (INIS)

    Ammonia gas (NH3) has been used as a nitrogen source for plasma source ion implantation processing of electroplated chromium. No evidence was found of increased hydrogen concentrations in the bulk material, implying that ammonia can be used without risking hydrogen embrittlement. The retained nitrogen dose of 2.1 x 1017 N-at/cm2 is sufficient to increase the surface hardness of electroplated Cr by 24% and decrease the wear rate by a factor of 4

  19. Occupational Exposure to Chromium of Assembly Workers in Aviation Industries.

    Science.gov (United States)

    Genovese, G; Castiglia, L; Pieri, M; Novi, C; d'Angelo, R; Sannolo, N; Lamberti, M; Miraglia, N

    2015-01-01

    Aircraft are constructed by modules that are covered by a "primer" layer, which can often contain hexavalent chromium [Cr(VI)], known carcinogen to humans. While the occupational exposure to Cr(VI) during aircraft painting is ascertained, the exposure assessment of assembly workers (assemblers) requires investigations. Three biological monitoring campaigns (BM-I,II,III) were performed in an aviation industry, on homogeneous groups of assemblers (N = 43) and controls (N = 23), by measuring chromium concentrations in end-shift urine collected at the end of the working week and the chromium concentration difference between end- and before-shift urines. BM-I was conducted on full-time workers, BM-II was performed on workers after a 3-4 day absence from work, BM-III on workers using ecoprimers with lower Cr(VI) content. Samples were analyzed by atomic absorption spectroscopy and mean values were compared by T-test. Even if Cr concentrations measured during BM-I were lower than Biological Exposure Indices by ACGIH, statistically significant differences were found between urinary Cr concentrations of workers and controls. Despite 3-4 days of absence from work, urinary chromium concentrations measured during BM-II were still higher than references from nonoccupationally exposed populations. In the BM-III campaign, the obtained preliminary results suggested the efficacy of using ecoprimers. The healthcare of workers exposed to carcinogenic agents follows the principle of limiting the exposure to "the minimum technically possible". The obtained results evidence that assemblers of aviation industries, whose task does not involve the direct use of primers containing Cr(VI), show an albeit slight occupational exposure to Cr(VI), that must be carefully taken into consideration in planning suitable prevention measures during risk assessment and management processes. PMID:25793365

  20. Chronic Maternal Dietary Chromium Restriction Modulates Visceral Adiposity

    OpenAIRE

    Padmavathi, Inagadapa J.N.; Rao, K Rajender; Venu, Lagishetty; Ganeshan, Manisha; Kumar, K. Anand; Rao, Ch. Narasima; Harishankar, Nemani; Ismail, Ayesha; Raghunath, Manchala

    2009-01-01

    OBJECTIVE We demonstrated previously that chronic maternal micronutrient restriction altered the body composition in rat offspring and may predispose offspring to adult-onset diseases. Chromium (Cr) regulates glucose and fat metabolism. The objective of this study is to determine the long-term effects of maternal Cr restriction on adipose tissue development and function in a rat model. RESEARCH DESIGN AND METHODS Female weanling WNIN rats received, ad libitum, a control diet or the same with ...

  1. Performance characteristics of mill rolls from graphite chromium cast iron

    OpenAIRE

    Lecomte-Beckers, Jacqueline; Terziev, L.; Breyer, J. P.

    2000-01-01

    The main requirements for the development of a new grade for the later finishing section of the mill are : good oxidation and thermal behaviour, high wear resistance, good resistance to rolling incidents. The approach of Marichal Ketin to improve the rolling performances in the last finishing stands is presented. The Hi-Cr cast iron possesses excellent wear resistance due to the presence of hard chromium carbides, but its thermal conductivity and sticking properties are fairly low. A graphite...

  2. Effect of oxygen concentration and temperature on compatibility of ODS steel with liquid, Stagnant Pb45Bi55

    International Nuclear Information System (INIS)

    Exposure tests of an oxide dispersion strengthened martensitic type steel (ODS) were performed in stagnant lead bismuth eutectic (LBE) containing 10-4, 10-6 and 10-8 wt% of oxygen at 500-650 deg. C up to 10 000 h. It resulted that the base metal was protected from corrosion by the formation of a magnetite and spinel layer in liquid Pb45Bi55 containing 10-6 wt% of oxygen at 550 deg. C or less, not however, at higher temperatures. At 650 deg. C and 10-8 wt% of oxygen, the ODS steel showed good compatibility with LBE by formation of a thin mixed high chromium spinel layer, while at 10-4 wt% multilayers of magnetite and spinel develop at this temperature which break off but are renewed by oxide layers which protect the steel again

  3. Effect of tritium on corrosion behavior of chromium in 0.01 N sulfuric acid solution

    International Nuclear Information System (INIS)

    The effects of tritium on the corrosion behavior of chromium in 0.01 N sulfuric solution have been investigated in the present study. Electrochemical experiments have been carried our for pure chromium. At first, the concentration dependence of sulfuric acid solution on anodic polarization behavior of chromium was experimented, resulting in that 0.01 N one was found appropriate. The dependence of both dissolved oxygen and tritium concentration on anodic behavior of chromium were performed. It was found from that the self-passivation of chromium induced by dissolved oxygen was inhibited in tritiated solution resulting in the enhancement of the corrosion. As a consequence it is highly likely that the elution of chromium by highly oxidative radiolysis products would explain the passivation inhibitory effect of SUS304 stainless steel observed in tritiated solutions

  4. Determination of Chromium(III) Picolinate Using High Performance Liquid Chromatography-Ultraviolet Spectrophotometry

    International Nuclear Information System (INIS)

    Cr-(pic)3 has been widely used as food additives, drugs, and feed additives. Accordingly, its determination method should be established. In the present paper, we have studied the determination method of chromium(III) picolinate accurately using ESI-MS on-lined with HPLC. Chromium(III) picolinate in feed products was determined successfully. Chromium(III) is very well known as an essential mineral. It is suggested as a cofactor in the maintenance of both normal lipid and carbohydrate metabolism by assisting the action of insulin on a cell membrane. According to the National Research Council, the daily recommended intake of chromium(III) is 50-200 μg. Several organic chromium(III) complexes have been reported to have significantly higher absorption and tissue incorporation activity than inorganic salts such as chromium(III) chloride

  5. Chemical composition and structural transformations of amorphous chromium coatings electrodeposited from Cr(III) electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Safonova, Olga V. [Swiss-Norwegian Beamlines at European Synchrotron Radiation Facility, 38043 Grenoble Cedex (France); Vykhodtseva, Ludmila N. [Department of Electrochemistry, Faculty of Chemistry, Moscow State University, 119991 Moscow (Russian Federation); Polyakov, Nikolai A. [A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119991 Moscow (Russian Federation); Swarbrick, Janine C. [European Synchrotron Radiation Facility, 38043 Grenoble Cedex (France); Sikora, Marcin [European Synchrotron Radiation Facility, 38043 Grenoble Cedex (France); Department of Solid State Physics, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Av. Mickiewicza 30, 30-059 Krakow (Poland); Glatzel, Pieter [European Synchrotron Radiation Facility, 38043 Grenoble Cedex (France); Safonov, Viktor A., E-mail: safon@elch.chem.msu.r [Department of Electrochemistry, Faculty of Chemistry, Moscow State University, 119991 Moscow (Russian Federation)

    2010-12-15

    Amorphous chromium coatings were electrodeposited from Cr(III)-based solutions containing organic (HCOONa) or phosphorus-containing (NaH{sub 2}PO{sub 2}) additives. Their structure was studied by a combination of X-ray diffraction (XRD), valence-to-core X-ray emission spectroscopy (XES) and X-ray absorption spectroscopy (XAS) at the Cr K-edge. Metalloid atoms (C or P) incorporated in electroplates structure are chemically bonded to chromium (i.e. are located in the first coordination shell). Upon annealing at elevated temperatures in vacuum, these amorphous coatings crystallize into a mixture of phases containing metallic chromium and chromium carbides or chromium phosphides. Quantitative analysis of valence-to-core XES data demonstrates that the average local structure of chromium in the amorphous coatings does not change significantly during crystallization.

  6. Fabrication of chitosan-magnetite nanocomposite strip for chromium removal

    Science.gov (United States)

    Sureshkumar, Vaishnavi; Kiruba Daniel, S. C. G.; Ruckmani, K.; Sivakumar, M.

    2016-02-01

    Environmental pollution caused by heavy metals is a serious threat. In the present work, removal of chromium was carried out using chitosan-magnetite nanocomposite strip. Magnetite nanoparticles (Fe3O4) were synthesized using chemical co-precipitation method at 80 °C. The nanoparticles were characterized using UV-visible spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction spectrometer, atomic force microscope, dynamic light scattering and vibrating sample magnetometer, which confirm the size, shape, crystalline nature and magnetic behaviour of nanoparticles. Atomic force microscope revealed that the particle size was 15-30 nm and spherical in shape. The magnetite nanoparticles were mixed with chitosan solution to form hybrid nanocomposite. Chitosan strip was casted with and without nanoparticle. The affinity of hybrid nanocomposite for chromium was studied using K2Cr2O7 (potassium dichromate) solution as the heavy metal solution containing Cr(VI) ions. Adsorption tests were carried out using chitosan strip and hybrid nanocomposite strip at different time intervals. Amount of chromium adsorbed by chitosan strip and chitosan-magnetite nanocomposite strip from aqueous solution was evaluated using UV-visible spectroscopy. The results confirm that the heavy metal removal efficiency of chitosan-magnetite nanocomposite strip is 92.33 %, which is higher when compared to chitosan strip, which is 29.39 %.

  7. Eolian transport of geogenic hexavalent chromium to ground water

    Science.gov (United States)

    Wood, W.W.; Clark, D.; Imes, J.L.; Councell, T.B.

    2010-01-01

    A conceptual model of eolian transport is proposed to address the widely distributed, high concentrations of hexavalent chromium (Cr+6) observed in ground water in the Emirate of Abu Dhabi, United Arab Emirates. Concentrations (30 to more than 1000 μg/L Cr+6) extend over thousands of square kilometers of ground water systems. It is hypothesized that the Cr is derived from weathering of chromium-rich pyroxenes and olivines present in ophiolite sequence of the adjacent Oman (Hajar) Mountains. Cr+3 in the minerals is oxidized to Cr+6 by reduction of manganese and is subsequently sorbed on iron and manganese oxide coatings of particles. When the surfaces of these particles are abraded in this arid environment, they release fine, micrometer-sized, coated particles that are easily transported over large distances by wind and subsequently deposited on the surface. During ground water recharge events, the readily soluble Cr+6 is mobilized by rain water and transported by advective flow into the underlying aquifer. Chromium analyses of ground water, rain, dust, and surface (soil) deposits are consistent with this model, as are electron probe analyses of clasts derived from the eroding Oman ophiolite sequence. Ground water recharge flux is proposed to exercise some control over Cr+6 concentration in the aquifer.

  8. Bioremediation of hexavalent chromium by a cyanobacterial mat

    Science.gov (United States)

    Shukla, Dhara; Vankar, Padma S.; Srivastava, Sarvesh Kumar

    2012-12-01

    The study comprises the use of cyanobacterial mat (collected from tannery effluent site) to remove hexavalent chromium. This mat was consortium of cyanobacteria/blue-green algae such as Chlorella sp., Phormidium sp. and Oscillatoria sp. The adsorption experiments were carried out in batches using chromium concentrations 2-10, 15-30 and 300 ppm at pH 5.5-6.2. The adsorption started within 15 min; however, 96 % reduction in metal concentration was observed within 210 min. The adsorption phenomenon was confirmed by Fourier transform-infrared spectroscopy and energy dispersive X-ray analysis. This biosorption fitted Freundlich adsorption isotherm very well. It was observed that the best adsorption was at 4 ppm, and at 25 ppm in the chosen concentration ranges. Scanning electron micrograph showed the physiology of mat, indicating sites for metal uptake. The main focus was collection of the cyanobacterial mat from local environments and its chromium removal potential at pH 5.5-6.2.

  9. Fabrication of Carbon Nanotube - Chromium Carbide Composite Through Laser Sintering

    Science.gov (United States)

    Liu, Ze; Gao, Yibo; Liang, Fei; Wu, Benxin; Gou, Jihua; Detrois, Martin; Tin, Sammy; Yin, Ming; Nash, Philip; Tang, Xiaoduan; Wang, Xinwei

    2016-03-01

    Ceramics often have high hardness and strength, and good wear and corrosion resistance, and hence have many important applications, which, however, are often limited by their poor fracture toughness. Carbon nanotubes (CNTs) may enhance ceramic fracture toughness, but hot pressing (which is one typical approach of fabricating CNT-ceramic composites) is difficult to apply for applications that require localized heat input, such as fabricating composites as surface coatings. Laser beam may realize localized material sintering with little thermal effect on the surrounding regions. However, for the typical ceramics for hard coating applications (as listed in Ref.[1]), previous work on laser sintering of CNT-ceramic composites with mechanical property characterizations has been very limited. In this paper, research work has been reported on the fabrication and characterization of CNT-ceramic composites through laser sintering of mixtures of CNTs and chromium carbide powders. Under the studied conditions, it has been found that laser-sintered composites have a much higher hardness than that for plasma-sprayed composites reported in the literature. It has also been found that the composites obtained by laser sintering of CNTs and chromium carbide powder mixtures have a fracture toughness that is ~23 % higher than the material obtained by laser sintering of chromium carbide powders without CNTs.

  10. Response of soil catalase activity to chromium contamination

    Institute of Scientific and Technical Information of China (English)

    Zofia St(e)pniewska; Agnieszka Woli(n)ska; Joanna Ziomek

    2009-01-01

    The impact of chromium (III) and (VI) forms on soil catalase activity is presented.The Orthic Podzol, Haplic Phaeozem and Mollic Gleysol from different depths were used in the experiment.The soil samples were amended with solution of Cr(III) using CrCl3, and with Cr(VI) using K2Cr2O7 in the concentration range from 0 to 20 mg/kg, whereas the samples without the addition of chromium served as control.Catalase activity was assayed by one of the commonly used spectrophotometric methods.As it is demonstrated in the experiment, both Cr(III) and Cr(VI) forms have ability to reduce soil catalase activity.A chromium dose of 20 mg/kg caused the inhibition of catalase activity and the corresponding contamination levels ranged from 75% to 92% for Cr(III) and 68% to 76% for Cr(VI), with relation to the control.Catalase activity reached maximum in the soil material from surface layers (0-25 cm), typically characterized by the highest content of organic matter creating favorable conditions for microorganisms.

  11. Selective Chromium(VI) Ligands Identified Using Combinatorial Peptoid Libraries

    Science.gov (United States)

    Knight, Abigail S.; Zhou, Effie Y.; Pelton, Jeffrey G.; Francis, Matthew B.

    2013-01-01

    Hexavalent chromium (Cr(VI)) is a world-wide water contaminant that is currently without cost-effective and efficient remediation strategies. This is in part due to a lack of ligands that can bind it amid an excess of innocuous ions in aqueous solution. We present herein the design and application of a peptoid-based library of ligand candidates for toxic metal ions. A selective screening process was used to identify members of the library that can bind to Cr(VI) species at neutral pH and in the presence of a large excess of spectator ions. Eleven sequences were identified, and their affinities were compared using titrations monitored with UV-Vis spectroscopy. To identify the interactions involved in coordination and specificity, we evaluated the effects of sequence substitutions and backbone variation in the highest affinity structure. Additional characterization of the complex formed between this sequence and Cr(VI) was performed using NMR spectroscopy. To evaluate the ability of the developed sequences to remediate contaminated solutions, the structures were synthesized on a solid-phase resin and incubated with environmental water samples that contained simulated levels of chromium contamination. The synthetic structures demonstrated the ability to reduce the amount of toxic chromium to levels within the range of the EPA contamination guidelines. In addition to providing some of the first selective ligands for Cr(VI), these studies highlight the promise of peptoid sequences as easily-prepared components of environmental remediation materials. PMID:24195610

  12. Structure and growth of oxide on iron-chromium alloys

    International Nuclear Information System (INIS)

    Several oxides form during the initial stages of oxidation of iron-chromium alloys at 400 to 6000C in CO2-1%CO gas. The nature of the oxidation product depends upon crystallographic orientation and composition of the substrate, and can be explained by considering the maximum solubility of chromium in different oxide phases together with interfacial and strain energy factors. Kinetics of oxidation together with micrographic observations indicate that, as oxidation proceeds spinel oxide M3O4 nucleates at sites on the substrate surface associated with asperities. The spinel nuclei grow laterally and vertically until they coalesce and the scale subsequently thickens according to a parabolic rate law. The duplex structure of scales is interpreted in terms of an outward diffusion of cations together with simultaneous growth of an inner layer in the space created by this outward movement. Scale porosity provides a route for gas-phase transport of oxidant to support the growth of the inner layer. Regularly spaced lamellar voids which may form in the inner layer are believed to be associated with a cyclic vacancy condensation process. Enrichment of the inner layer in chromium is explained by analysis of the possible diffusion path networks in close-packed oxides. Some comments are made concerning possible practical applications of these data. (author)

  13. [Remediation of chromium (VI) contaminated soils using permeable reactive composite electrodes technology].

    Science.gov (United States)

    Fu, Rong-Bing; Liu, Fang; Ma, Jin; Zhang, Chang-Bo; He, Guo-Fu

    2012-01-01

    Electrokinetic transport processes have been shown to have potential for the effective removal of heavy metals from soils. However, pH changes near the anode and cathode limit their widespread application in the remediation of contaminated soils. Permeable reactive composite electrodes (PRCE) were made by attaching reactive materials such as Fe(0) and zeolite to the electrodes, and the effects of the composite electrodes on pH control, chromium removal efficiency and Cr speciation changes were studied in the electrokinetic remediation process of Cr( VI) contaminated soil. Composite electrodes consisting of permeable reactive materials gave better pH control and Cr removal efficiency compared to traditional electrodes, and a Fe(0) + zeolite reactive layer in the anode exhibited the best performance compared to zeolite or Fe(0) alone. After 5 days of electrokinetic remediation with a DC voltage of 2 V x cm(-1), the Fe(0) + zeolite reactive layer lowered the pH fluctuation, maintained the soil pH in the range of 5.5 to 8.5, raised the Cr(VI) removal efficiency up to 97% in any soil section, produced lower Cr(III) residues, enhanced the amount of Cr retention up to 8 and 1.8 times respectively, and transformed 98% of the Cr(VI) into lower toxicity Cr(III). This study provides a theoretical basis for the exploitation of permeable reactive composite electrodes which are a practical option for future applications. PMID:22452223

  14. Speciation of chromium using chronoamperometric biosensors based on screen-printed electrodes.

    Science.gov (United States)

    Calvo-Pérez, Ana; Domínguez-Renedo, Olga; Alonso-Lomillo, M Asunción; Arcos-Martínez, M Julia

    2014-06-23

    Chronoamperometric assays based on tyrosinase and glucose oxidase (GOx) inactivation have been developed for the monitoring of Cr(III) and Cr(VI). Tyrosinase was immobilized by crosslinking on screen-printed carbon electrodes (SPCEs) containing tetrathiafulvalene (TTF) as electron transfer mediator. The tyrosinase/SPC(TTF)E response to pyrocatechol is inhibited by Cr(III). This process, that is not affected by Cr(VI), allows the determination of Cr(III) with a capability of detection of 2.0±0.2 μM and a reproducibility of 5.5%. GOx modified screen-printed carbon platinised electrodes (SPCPtEs) were developed for the selective determination of Cr(VI) using ferricyanide as redox mediator. The biosensor was able to discriminate two different oxidation states of chromium being able to reject Cr(III) and to detect the toxic species Cr(VI). Chronoamperometric response of the biosensor towards glucose decreases with the presence of Cr(VI), with a capability of detection of 90.5±7.6 nM and a reproducibility of 6.2%. A bipotentiostatic chronoamperometric biosensor was finally developed using a tyrosinase/SPC(TTF)E and a GOx/SPC(Pt)E connected in array mode for the simultaneous determination of Cr(III) and Cr(VI) in spiked tap water and in waste water from a tannery factory samples. PMID:24909769

  15. Chromium related degradation of solid oxide fuel cells; Chrom-bezogene Degradation von Festoxid-Brennstoffzellen

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, Anita

    2011-05-04

    Solid Oxide Fuel Cells (SOFCs) offer a high potential for application as an auxiliary power unit (APU) for heavy goods vehicles as well as combined heat and power (CHP) systems. SOFCs are especially attractive due to their high efficiencies and the use of different fuel types. However, optimization in terms of long term stability and costs are still necessary. This work characterized the degradation of SOFCs with lanthanum strontium manganite (LSM) cathodes under chromium influence. Galvanostatic cell tests were carried out at 800 C with operation times from 250 - 3000 h and variation of the chromium source and current density. The current densities of j = 0 (A)/(cm{sup 2}), j = 0,3 (A)/(cm{sup 2}) and j = 0,5 (A)/(cm{sup 2}) were applied. The high temperature ferritic alloy Crofer22APU was used as a chromium source. Variation of the chromium source was realized by coating the Crofer22APU insert with the chromium retention layer Mn{sub 3}O{sub 4} and the cathode contact layer LCC10. Cell degradation was analyzed with regard to cell voltage, current density and area specific resistance (ASR). Microstructural alterations of the cathode as well as chromium content and distribution across the cell were investigated after completion of the cell tests. For cells with a chromium source present and operation with a nonzero current density, the course of cell degradation was divided into three phases: a run-in, weak linear degradation and strong linear degradation. A decrease of the chromium release rate by means of different coatings stretched the course of degradation along the timescale. Strong degradation, which is characterized by a significant increase in ASR as well as a decrease of current density at the operating point, was only observed when a chromium source in the setup was comb ined with operation of the cell with a non-zero current density. Operation of the cell with a chromium source but no current density caused a degradation of current density at the

  16. Determination of Chromium Content in Human Skin by Means of Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Chromium eczema is a well-known phenomenon in dermatological practice. Different explanations may be given for it. According to one of these the specific texture of the skin of patients is assumed to allow more chromium to pass through the upper layers. As a result, the chromium accumulates faster in the dermis of patients so that a critical value is reached sooner. Another explanation might be that die sensitivity threshold for chromium in patients is lower than in normal persons and can more easily be exceeded. To distinguish between these possibilities and to obtain more information, an investigation was started in which the chromium content in the skin was compared for eczema patients and normal people. The sample weight (10 mg) and the chromium content (0.2 - 0.4 ppm) involved require a sensitive technique. Neutron activation analysis is well suited to this purpose. Under our operation conditions (irradiation time 10 days, neutron flux 1014n/cm2s) it is possible to determine quantities as low as 5 x 10-11 g of chromium. Preliminary experiments show relatively large variations in chromium content of comparable samples, even in skin samples taken from the back of a single person. It is further suggested by the results of these experiments that the chromium content in the skin of eczema patients is lower than in that of normal patients. The results of the analysis may be seriously affected by chromium contamination during sample preparation. Therefore chromium-free instruments must be used. To avoid chromium migration in the skin due to degeneration processes, samples must be taken from persons alive or shortly after their death. (author)

  17. Characteristics of Aerosols Containing Chromium and Nickel From Some Thermal Spraying Operations

    OpenAIRE

    Bohgard, Mats; Welinder, Hans; Akselsson, Roland

    1983-01-01

    Characterization of aerosols, emitted from five methods of thermal spraying with materials containing chromium and nickel were carried out. The characterization procedure includes the determinations of the metal content, the particle size distribution, the oxidation state of chromium and a measure of the solubility of chromium. Three different kinds of samplers and the analytical methods PIXE (Particle Induced X-ray Emission analysis), ESCA (Electron Spectroscopy for Chemical Analysis), AAS (...

  18. Optimization and Modeling of Hexavalent Chromium Removal from Aqueous Solution Via Adsorption on Multiwalled Carbon Nanotubes

    OpenAIRE

    Mina Gholipour; Hassan Hashemipour Rafsanjani; Ataollah Soltani Goharrizi

    2011-01-01

    Hexavalent chromium and its derivatives are potential pollutant due to their mortal affects. Therefore, It is essential to remove these components from wastewaters before disposal. Adsorption can be effective and versatile method for removing of hexavalent chromium. In this article, removal of hexavalent chromium via adsorption on multiwalled carbon nanotubes was investigated as a function of adsorbent dosage, initial solution pH, initial Cr(VI) concentrations, contact time and temperature. T...

  19. Enhancing phytoremediation of chromium-stressed soils through plant-growth-promoting bacteria

    OpenAIRE

    Munees Ahemad

    2015-01-01

    Chromium, specifically hexavalent chromium is one of the most toxic pollutants that are released into soils by various anthropogenic activities. It has numerous adverse effects not only on plant system but also on beneficial soil microorganisms which are the indicators of soil fertility and health. Recent emergence of phytoremediation as an environmental friendly and economical approach to decontaminate the chromium stressed soils has received wider attention. But major drawback of this proce...

  20. Si doped and undoped chromium nitride coatings : a comparative study of physical properties

    OpenAIRE

    CUNHA L.; Moura, C.

    2011-01-01

    Chromium nitride and silicon doped chromium nitride thin films have been deposited by r.f. reactive magnetron sputtering. This study corresponds to the investigation of the influence of processing parameters and of the addition of silicon on the chromium nitride matrix on the properties of the produced films. The characterization of the coatings was performed by X-ray diffraction (XRD), and nano-indentation experiments. Results concerning the crystalline phases, crystal orientation/texture...

  1. Removal of hexavalent chromium of contaminated soil by coupling electrokinetic remediation and permeable reactive biobarriers

    OpenAIRE

    Fonseca, Bruna; Pazos, M.; Tavares, M. T.; Sanromán, M. A.

    2012-01-01

    PURPOSE: In this study, a novel and ecological alternative have been developed to treat soils contaminated with hexavalent chromium coupling two well-known systems: electrokinetic remediation and permeable reactive biobarriers. The electric field promotes the electromigration of the hexavalent chromium oxyanions towards the anode. The biobarriers were placed before the anode electrode, in order to promote the reduction and retention of the chromium migrating in its direction. Thus, this t...

  2. Evaluation of a method for the determination of chromium in urine by atomic absorption spectrometry

    International Nuclear Information System (INIS)

    A method for the determination of chromium in urine by atomic absorption spectrometry, using electrothermic atomization with pyrolytic graphite tubes, is proposed. The determinations are performed by standard addition. The method is applicable to biologic monitoring of populations with different degrees of exposition. It is also used in the analysis of chromium in sediments. Results of chromium in urine of a population group non-exposed to the metal are presented. 11 refs

  3. Chromium does not belong in the diabetes treatment arsenal: Current evidence and future perspectives

    OpenAIRE

    Landman, Gijs WD; Bilo, Henk JG; Houweling, Sebastiaan T.; Kleefstra, Nanne

    2014-01-01

    Chromium is considered to have positive effects on insulin sensitivity and is marketed as an adjunctive therapy for inducing glucose tolerance in cases of insulin resistance (“the glucose tolerance factor”). Case reports on patients who received prolonged parenteral nutrition indeed showed that the absence of trivalent chromium caused insulin resistance and diabetes. However, whether patients with type 2 diabetes can develop a clinically relevant chromium deficiency is unclear. This review su...

  4. Environmental optimization of chromium recovery from tannery sludge using a life cycle assessment approach

    OpenAIRE

    Kiliç, Eylem; Puig Vidal, Rita; Baquero Armans, Grau; Font Vallès, Joaquim; Colak, Selime; Gürler, Deniz

    2011-01-01

    Life cycle assessment (LCA) was used to evaluate the environmental impact of an oxidative chromium recovery method from tannery sludge, in comparison with the usual landfilling process. Three improvement options (water reduction, byproduct use and anaerobic sludge digestion) were considered. The results showed that the proposed chromium recovery process would be better environmentally than conventional landfilling in all the evaluated impact categories if the amount of chromium recovered w...

  5. Use of molecular epidemiological techniques in a pilot study on workers exposed to chromium.

    OpenAIRE

    Gao, M; Levy, L S; Faux, S. P.; AW, T C; Braithwaite, R. A.; Brown, S. S.

    1994-01-01

    OBJECTIVES--Molecular epidemiological techniques, capable of detecting damage to DNA, were used to see if such damage occurred in the lymphocytes of a group of workers exposed to chromium. The two aims of this pilot study were to see if these new techniques might make useful biological monitoring tools for workers exposed to chromium and also, to help assess whether the current occupational exposure limit for chromium (VI) was sufficiently protective in this specific working situation. METHOD...

  6. Effects of chromic-acid concentration on the structure and properties of chromium coatings

    Energy Technology Data Exchange (ETDEWEB)

    Solodkova, L.N.; Solov' eva, Z.A.; Monev, M.; Nikolova, S.; Rashkov, S.; Dobrev, Ts.

    1987-10-01

    In the interest of decreasing the amount of chromium and other electrolytic effluents that enter the waste stream during chromium electrodeposition processes, and of optimizing plating speeds at reduced chromic acid concentrations, the authors seek to establish the effects of decreasing the chromic acid concentration in the electrolyte on the microstructure, microhardness, internal stress behavior, and tendency toward hydridation of chromium coatings obtained from various electrolyte compositions. Plating kinetics and lattice parameters were also investigated.

  7. Severe insulin resistance treatment with intravenous chromium in septic shock patient

    OpenAIRE

    2012-01-01

    Insulin resistance has been well documented in critically ill patients. Adequate blood sugar control has been associated with better wound healing, and better outcomes in selected patient populations. Chromium is an essential component of human diet. It is believed to affect changes in glucose uptake. Several studies have shown beneficial effects of oral chromium in diabetic patients with insulin resistance, but role of intravenous chromium infusion has not been completely evaluated. We prese...

  8. Chromium picolinate improves insulin sensitivity in obese subjects with polycystic ovary syndrome.

    Science.gov (United States)

    Lydic, Michael L; McNurlan, Margaret; Bembo, Shirley; Mitchell, Lina; Komaroff, Eugene; Gelato, Marie

    2006-07-01

    Trivalent chromium (1000 microg), as chromium picolinate, given without change in diet or activity level, caused a 38% mean improvement in glucose disposal rate in five obese subjects with polycystic ovary syndrome who were tested with a euglycemic hyperinsulinemic clamp technique. This suggests that chromium picolinate, an over-the-counter dietary product, may be useful as an insulin sensitizer in the treatment of polycystic ovary syndrome. PMID:16730719

  9. 36 CFR 251.55 - Nature of interest.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Nature of interest. 251.55 Section 251.55 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE LAND USES Special Uses § 251.55 Nature of interest. (a) A holder is authorized only to occupy such land...

  10. 47 CFR 61.55 - Contract-based tariffs.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Contract-based tariffs. 61.55 Section 61.55 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) TARIFFS General Rules for Dominant Carriers § 61.55 Contract-based tariffs. (a) This section shall apply to price...

  11. 9 CFR 55.6 - Mortgage against animals.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Mortgage against animals. 55.6 Section 55.6 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF... DISEASE Chronic Wasting Disease Indemnification Program § 55.6 Mortgage against animals. When cervids...

  12. 9 CFR 55.5 - Presentation of claims for indemnity.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Presentation of claims for indemnity. 55.5 Section 55.5 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT... CHRONIC WASTING DISEASE Chronic Wasting Disease Indemnification Program § 55.5 Presentation of claims...

  13. 10 CFR 1.55 - Establishment of official NRC flag.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Establishment of official NRC flag. 1.55 Section 1.55 Energy NUCLEAR REGULATORY COMMISSION STATEMENT OF ORGANIZATION AND GENERAL INFORMATION NRC Seal and Flag § 1.55 Establishment of official NRC flag. The official flag is based on the design of the NRC...

  14. 30 CFR 47.55 - Retaining an MSDS.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Retaining an MSDS. 47.55 Section 47.55 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR EDUCATION AND TRAINING HAZARD COMMUNICATION (HazCom) Material Safety Data Sheets (MSDS) § 47.55 Retaining an MSDS. The operator must— (a) Retain its MSDS for as long as...

  15. 36 CFR 1192.55 - Priority seating signs.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Priority seating signs. 1192.55 Section 1192.55 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS... Rapid Rail Vehicles and Systems § 1192.55 Priority seating signs. (a) Each vehicle shall contain...

  16. 49 CFR 38.55 - Priority seating signs.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Priority seating signs. 38.55 Section 38.55 Transportation Office of the Secretary of Transportation AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES Rapid Rail Vehicles and Systems § 38.55 Priority seating signs....

  17. 42 CFR 432.55 - Reporting training and administrative costs.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 4 2010-10-01 2010-10-01 false Reporting training and administrative costs. 432.55 Section 432.55 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL ASSISTANCE PROGRAMS STATE PERSONNEL ADMINISTRATION Staffing and Training Expenditures § 432.55 Reporting training...

  18. 46 CFR 201.55 - Postponement of hearing.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 8 2010-10-01 2010-10-01 false Postponement of hearing. 201.55 Section 201.55 Shipping MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION POLICY, PRACTICE AND PROCEDURE RULES OF PRACTICE AND PROCEDURE Time (Rule 5) § 201.55 Postponement of hearing. Applications for postponement of any hearing...

  19. 28 CFR 55.20 - Oral assistance and publicity.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Oral assistance and publicity. 55.20 Section 55.20 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS... Assistance § 55.20 Oral assistance and publicity. (a) General. Announcements, publicity, and...

  20. 46 CFR 112.55-10 - Storage battery charging.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Storage battery charging. 112.55-10 Section 112.55-10... AND POWER SYSTEMS Storage Battery Installation § 112.55-10 Storage battery charging. (a) Each storage battery installation for emergency lighting and power, and starting batteries for an emergency diesel...

  1. 49 CFR 570.55 - Hydraulic brake system.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 6 2010-10-01 2010-10-01 false Hydraulic brake system. 570.55 Section 570.55... 10,000 Pounds § 570.55 Hydraulic brake system. The following requirements apply to vehicles with hydraulic brake systems. (a) Brake system failure indicator. The hydraulic brake system failure...

  2. 4 CFR 5.5 - Travel, transportation, and subsistence.

    Science.gov (United States)

    2010-01-01

    ... 4 Accounts 1 2010-01-01 2010-01-01 false Travel, transportation, and subsistence. 5.5 Section 5.5 Accounts GOVERNMENT ACCOUNTABILITY OFFICE PERSONNEL SYSTEM COMPENSATION § 5.5 Travel, transportation, and subsistence. The provisions of chapter 57 of title 5, U.S. Code and the implementing regulations for...

  3. 31 CFR 103.55 - Exceptions, exemptions, and reports.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Exceptions, exemptions, and reports. 103.55 Section 103.55 Money and Finance: Treasury Regulations Relating to Money and Finance FINANCIAL RECORDKEEPING AND REPORTING OF CURRENCY AND FOREIGN TRANSACTIONS General Provisions § 103.55...

  4. 49 CFR 37.55 - Intercity rail station accessibility.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Intercity rail station accessibility. 37.55 Section 37.55 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.55 Intercity rail station...

  5. 4 CFR 28.55 - Scheduling the hearing.

    Science.gov (United States)

    2010-01-01

    ... 4 Accounts 1 2010-01-01 2010-01-01 false Scheduling the hearing. 28.55 Section 28.55 Accounts GOVERNMENT ACCOUNTABILITY OFFICE GENERAL PROCEDURES GOVERNMENT ACCOUNTABILITY OFFICE PERSONNEL APPEALS BOARD... Procedures Hearings § 28.55 Scheduling the hearing. The notice of initial hearing shall fix the date,...

  6. 40 CFR 205.55-1 - General requirements.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false General requirements. 205.55-1 Section 205.55-1 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks § 205.55-1...

  7. 40 CFR 205.55-2 - Compliance with standards.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Compliance with standards. 205.55-2 Section 205.55-2 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks § 205.55-2...

  8. 40 CFR 205.55-4 - Labeling-compliance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Labeling-compliance. 205.55-4 Section 205.55-4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks § 205.55-4...

  9. 40 CFR 205.55-3 - Configuration identification.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Configuration identification. 205.55-3 Section 205.55-3 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks § 205.55-3...

  10. 40 CFR 205.55-5 - Labeling-exterior. [Reserved

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Labeling-exterior. 205.55-5 Section 205.55-5 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Medium and Heavy Trucks § 205.55-5...

  11. 46 CFR 64.55 - Relief device location.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Relief device location. 64.55 Section 64.55 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Standards for an MPT § 64.55 Relief device location. A pressure relief...

  12. 7 CFR 1788.55 - Providing RUS evidence.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 12 2010-01-01 2010-01-01 false Providing RUS evidence. 1788.55 Section 1788.55... AGRICULTURE (CONTINUED) RUS FIDELITY AND INSURANCE REQUIREMENTS FOR ELECTRIC AND TELECOMMUNICATIONS BORROWERS Insurance for Contractors, Engineers, and Architects, Telecommunications Borrowers § 1788.55 Providing...

  13. 21 CFR 7.55 - Termination of a recall.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Termination of a recall. 7.55 Section 7.55 Food... POLICY Recalls (Including Product Corrections)-Guidance on Policy, Procedures, and Industry Responsibilities § 7.55 Termination of a recall. (a) A recall will be terminated when the Food and...

  14. USE OF TWO DIGESTION METHODS IN THE EVALUATION OF CHROMIUM CONTENT IN CATTLE'S MEAT SUPPLEMENTED WITH CHROMIUM CHELATES

    Directory of Open Access Journals (Sweden)

    R. L. T. de Andrade

    2015-06-01

    Full Text Available The present study aimed to analyze the chromium content in beef using two digestion methods. There were used samples from 24 18-month-old male cattle, and twelve of them were supplemented and twelve were not supplemented with chromium chelate. These samples were evaluated by atomic absorption spectroscopy, previously submitted to digestion method using nitric acid (65% with hydrogen peroxide (35% and to digestion method, using solution of nitric perchloric acid in the proportion 3:1. Immediately after the slaughter, the carcasses were sent to sanitary maturation. After 24 hours, samples between 12th and 13th rib in the muscle Longissimus Thoracis were taken. For evaluation, it was used completely randomized design (Die and analysis of variance (ANOVA at 5% of significance level. The results didn't evidenced any significant difference (p>0,05 between the (cromo content, regardless the supplementation. The same happened with the digestion methods used.

  15. 14-3-3/HIP-55 complex increases the stability of HIP-55%14-3-3/HIP-55复合体增强HIP-55蛋白稳定性

    Institute of Scientific and Technical Information of China (English)

    田爱炬; 李子健

    2015-01-01

    目的:用双分子荧光互补及免疫共沉淀技术验证HIP-55与14-3-3在HEK293细胞中存在相互作用,并进一步研究其生物学意义. 方法:利用GATEWAY系统构建PDEST-N-Venus-HIP-55WT(野生型),PDEST-N-Venus-HIP-55AA(突变体S269A/T291A),PDEST-GST-HIP-55WT及PDEST-C-Venus-14-3-3τ重组质粒,利用双分子荧光互补及免疫共沉淀技术检测两者的相互作用,同时应用14-3-3蛋白相互作用抑制肽R18和HIP-55蛋白突变体( HIP-55AA突变体S269A/T291A不能与14-3-3相互作用)作为工具研究两者结合后对嘌呤霉素诱导的HIP-55蛋白表达的影响. 结果:外源转入的Venus-HIP-55WT、Venus-HIP-55AA及Venus-14-3-3蛋白能够在HEK293细胞中表达;双分子荧光互补实验结果表明HIP-55与14-3-3存在相互作用,HIP-55蛋白的S269/T291位点介导HIP-55与14-3-3的相互作用;免疫共沉淀技术表明内源性HIP-55与14-3-3存在相互作用;进一步研究发现HIP-55与14-3-3复合体增强HIP-55蛋白的稳定性,保护HIP-55不被降解. 结论:14-3-3与HIP-55存在相互作用,14-3-3/HIP-55复合体可以促进HIP-55蛋白的稳定性.%Objective:To further demonstrate the interaction of a new 14-3-3 interaction protein hema-topoietic progenitor kinase 1 [ HPK1 ]-interacting protein ( HIP-55 ) and 14-3-3 proteins and its potential biological function in HEK293 cells. Methods:PDEST-N-Venus-HIP-55WT (wild type),PDEST-N-Ve-nus-HIP-55AA (mutants, S269A/T291A, abolishing the binding of HIP-55 to 14-3-3),PDEST-GST-HIP-55WT and PDEST-C-Venus-14-3-3τplasmids were constructed by gateway system. Their expressions were demonstrated by Western blotting method. Then we used Bimolecular Fluorescence Complementation ( BiFC) and co-immunoprecipitation ( co-IP) methods to demonstrate the interaction of HIP-55 and 14-3-3 in HEK293 cells. Moreover, the 14-3-3 antagonist peptide, R18 and HIP-55 protein mutant plasmid HIP-55 AA were used to detect the protein synthesis of HIP-55 at different time points

  16. Corrosion behavior of HVOF-sprayed and Nd-YAG laser-remelted high-chromium, nickel-chromium coatings

    Science.gov (United States)

    Tuominen, J.; Vuoristo, P.; Mäntylä, T.; Ahmaniemi, S.; Vihinen, J.; Andersson, P. H.

    2002-06-01

    Thermal spray processes are widely used to deposit high-chromium, nickel-chromium coatings to improve high temperature oxidation and corrosion behavior. However, despite the efforts made to improve the present spraying techniques, such as high-velocity oxyfuel (HVOF) and plasma spraying, these coatings may still exhibit certain defects, such as unmelted particles, oxide layers at splat boundaries, porosity, and cracks, which are detrimental to corrosion performance in severe operating conditions. Because of the process temperature, only mechanical bonding is obtained between the coating and substrate. Laser remelting of the sprayed coatings was studied in order to overcome the drawbacks of sprayed structures and to markedly improve the coating properties. The coating material was high-chromium, nickel-chromium alloy, which contains small amounts of molybdenum and boron (53.3% Cr, 42.5% Ni, 2.5% Mo, 0.5% B). The coatings were prepared by HVOF spraying onto mild steel substrates. A high-power, fiber-coupled, continuous-wave Nd:YAG laser equipped with large beam optics was used to remelt the HVOF-sprayed coating using different levels of scanning speed and beam width (10 or 20 mm). Coating that was remelted with the highest traverse speed suffered from cracking because of the rapid solidification inherent to laser processing. However, after the appropriate laser parameters were chosen, nonporous, crack-free coatings with minimal dilution between coating and substrate were produced. Laser remelting resulted in the formation of a dense oxide layer on top of the coatings and full homogenization of the sprayed structure. The coatings as sprayed and after laser remelting were characterized by optical and electron microscopy (OM, SEM, respectively). Dilution between coating and substrate was studied with energy dispersive spectrometry (EDS). The properties of the laser-remelted coatings were directly compared with properties of as-sprayed HVOF coatings.

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

    Energy Technology Data Exchange (ETDEWEB)

    Krumpolc, M. (Illinois Univ., Chicago, IL (USA)); Hill, D. (Argonne National Lab., IL (USA)); Struhrmann, H.B. (Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany, F.R.). Hamburger Synchrotronstrahlungslabor)

    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.

  18. Improvement on simultaneous determination of chromium species in aqueous solution by ion chromatography and chemiluminescence detection

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Liao, Y.P.; Jons, O.

    sulphite, whereupon both species were detected by use of the luminol-hydrogen peroxide chemiluminescence system. Parameters affecting retention times and resolution of the separator columns, such as eluent pH, eluent composition, reductant pH and concentration, and flow rates were optimized. Furthermore......, the stabilities of reductant and luminol solutions were studied. The linear range of the calibration curve for chromium(III) and chromium(VI) was 1-400 mu g l(-1). The detection limit was 0.12 mu g l(-1) for chromium(III) and 0.09 mu g l(-1) for chromium(VI), respectively. The precision at the 20 mu g...

  19. Detergents and bleaches are sources of chromium contact dermatitis in Israel

    DEFF Research Database (Denmark)

    Ingber, A; Gammelgaard, Bente; David, M

    1998-01-01

    Total chromium levels were determined in 38 detergents and 12 bleaches on the market in Israel (45 locally produced, 5 imported). The samples were analyzed by Zeeman-corrected graphite furnace atomic absorption spectrophotometry. Chromium levels were higher than 5 ppm in 28 (56%) of the 50 products......, from 1 to 5 ppm in 16 (32%), and lower than 1 ppm in only 6 (12%). Among the 5 imported products, only 1 had a chromium level below 1 ppm and the other 4 (1 from Germany, 3 from the USA) had high levels. Since a most 90% of the detergents and bleaches examined contained chromium levels higher than 1...

  20. The determination of nanogram amounts of Chromium in urine by x-ray fluorescence spectroscopy

    Science.gov (United States)

    Beyermann, K.; Rose, H.J., Jr.; Christian, R.P.

    1969-01-01

    Nanogram amounts of chromium can be extracted as oxinate into chloform. By treatment of the chloroform layer 3 M hydrochloric acid, oxinates of other elements and excess of reagent are removed, leaving a chloroform solution of the chromium chelate only. This solution is concentrated and transferred to the top of a small brass rod acting as sample holder. The intensity of the X-ray fluorescence of the Cr K?? line is measured with curved crystal optics. Chromium amounts greater than 5 ng can be detected. The application of the procedure to the analysis of the chromium content of urine is demonstrated. ?? 1969.

  1. Hexavalent chromium and its effect on health: possible protective role of garlic (Allium sativum Linn).

    Science.gov (United States)

    Das, Kusal K; Dhundasi, Salim A; Das, Swastika N

    2011-01-01

    Hexavalent chromium or chromium (VI) is a powerful epithelial irritant and a confirmed human carcinogen. This heavy metal is toxic to many plants, aquatic animals, and bacteria. Chromium (VI) which consists of 10%-15% total chromium usage, is principally used for metal plating (H2Cr2O7), as dyes, paint pigments, and leather tanning, etc. Industrial production of chromium (II) and (III) compounds are also available but in small amounts as compared to chromium (VI). Chromium (VI) can act as an oxidant directly on the skin surface or it can be absorbed through the skin, especially if the skin surface is damaged. The prooxidative effects of chromium (VI) inhibit antioxidant enzymes and deplete intracellular glutathione in living systems and act as hematotoxic, immunotoxic, hepatotoxic, pulmonary toxic, and nephrotoxic agents. In this review, we particularly address the hexavalent chromium-induced generation of reactive oxygen species and increased lipid peroxidation in humans and animals, and the possible role of garlic (Allium sativum Linn) as a protective antioxidant. PMID:22865357

  2. Biosorption and biotransformation of chromium by Serratia sp. isolated from tannery effluent.

    Science.gov (United States)

    Srivastava, Shaili; Thakur, Indu Shekhar

    2012-01-01

    A bacterium isolated from soil and sediment ofa leather tanning mill's effluent was identified as Serratia sp. by the analysis of 16S rDNA. Scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) and transmission electron microscopy (TEM) were used to assess morphological changes and confirm chromium biosorption in Serratia sp. both in a shake-flask culture containing chromium and in a tannery wastewater. The SEMEDX and the elemental analysis of the chromate-containing samples confirmed the binding of chromium with the bacterial biomass. The TEM exhibited chromium accumulation throughout the bacterial cell, with some granular deposits in the cell periphery and in the cytoplasm. X-ray diffraction analysis (XRD) was used to quantify the chromium and to determine the chemical nature of the metal-microbe interaction. The XRD data showed the crystalline character of the precipitates, which consisted of mainly calcium chromium oxide, chromium fluoride phosphate and related organo-Cr(III) complex crystals. The XRD data also revealed a strong involvement of cellular carboxyl and phosphate groups in chromium binding by the bacterial biomass. The results of the study indicated that a combined mechanism of ion-exchange, complexation, croprecipitation and immobilization was involved in the biosorption of chromium by bacterial cells in contaminated environments. PMID:22519094

  3. Chromium recovery from exhausted baths generated in plating processes and its reuse in the tanning industry.

    Science.gov (United States)

    Torras, Josep; Buj, Irene; Rovira, Miquel; de Pablo, Joan

    2012-03-30

    Chromium plating used for functional purposes provides an extremely hard, wear and corrosion resistant layer by means of electrolytic deposition. Typical layer thicknesses range between 2.5 and 500 μm. Chromium electroplating baths contain high concentrations of Cr(VI) with chromium trioxide (CrO(3)) as the chromium source. When because of technical or economic reasons a bath gets exhausted, a waste containing mainly chromium as dichromate as well as other heavy metals is generated. Chromium may then be purified for use in other industrial processes with different requirements. In this work, a sustainable system for using galvanic wastes as reagents in the leather tanning industry, thus reducing quantity of wastes to be treated, is presented. Metal cations present in the chromium exhausted bath were precipitated with NaOH. Then, the solution containing mainly soluble Cr(VI) was separated. By means of sodium sulphite in acidic conditions, Cr(VI) was reduced to Cr(III) as chromium (III) sulphate. From chromium (III) sulphate a basic Cr(III) sulphate may be obtained, which is one of most used compounds in the tanning industry. Cr(III) concentration in the final solution allows its reuse without concentration, but with a slight dilution. PMID:22326242

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

    International Nuclear Information System (INIS)

    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

  5. ANTIBIOTIC RESISTANCE AND CHROMIUM REDUCTION PATTERN AMONG ACTINOMYCETES

    Directory of Open Access Journals (Sweden)

    Preeti Jain

    2012-01-01

    Full Text Available Actinomycetes, one of the most important groups of microbes, exhibit many interesting activities such as degradation and transformation of organic and metal substrates together with production of antibiotics. With these bioactivities, actinomycetes would play an important role in the webs of the marine environment. The present study was designed to evaluate the antibiotic resistance pattern, antibiotic producing potential and chromium resistance as well as chromium reduction potential of a range of actinomycetes isolated from marine environments. Actinomycetes were isolated from marine sediment samples obtained from St. Martin’s Island in Bangladesh. Antibiotic resistance among the selected isolates was studied against 10 different antibiotics by disc diffusion method and antibiotic producing potential was assessed by the perpendicular streak method. The isolates were screened for resistance towards heavy metal Cr(VI on culture plates supplemented with Cr(VI at concentrations ranging from 1-5 mM of Cr(VI. Highly resistant isolates were subjected to screening for Cr(VI reduction activity, which was estimated using the Cr(VI specific colorimetric reagent 1, 5-diphenylcarbazide. Out of the total 30 different selected isolates, 25 (83.33% showed resistance against more than three antibiotics and 6 (20% showed resistance to more than six antibiotics. Ninety three percent of the isolates showed MAR index greater than 0.2 and tolerance to Cr(VI at 1mM of initial Cr(VI. None of the isolates displayed antimicrobial activity against the organisms tested. Among the isolates tested for chromate reduction, two were most efficient showing complete reduction of 1mM Cr(VI within 24 h. These two isolates (SM-11, SM-20 were capable of reducing chromate even at high initial Cr(VI concentrations. Remarkably, the isolate SM-11 was found to reduce 82.67%, 44.34% of Cr(VI at 2.5mM, 5mM of initial Cr(VI concentrations respectively, within 72h of incubation. The

  6. Investigation of surrogate method for 55Fe(n,p)55Mn reaction cross-section measurement

    International Nuclear Information System (INIS)

    In the present work the feasibility study of surrogate technique for the cross-section measurement of 55Fe(n, p)55Mn is done. This reaction is very important in fusion environment as 55Fe (t1/2=2.73 years) is produced via 56Fe(n,2n)55Fe nuclear reaction with fast neutrons. It will be first time that we use surrogate method in fusion applications in this mass region

  7. 49 CFR 1242.82 - Other and casualties and insurance (accounts XX-55-99 and 50-55-00).

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Other and casualties and insurance (accounts XX-55... RAILROADS 1 Operating Expenses-Transportation § 1242.82 Other and casualties and insurance (accounts XX-55... separation of administration (account XX-55-01). Operating Expenses general and administration...

  8. Effect of Chromium Supplementation on Glucose Metabolism and Lipids: A Systematic Review with Meta-Analysis of Randomized Controlled Trials

    Science.gov (United States)

    Objective. A systematic review of the effect of chromium supplementation on glucose metabolism and lipid levels. Research Design and Methods. Literature search conducted in MEDLINE and Commonwealth Agricultural Bureau. Eligible studies were English language randomized controlled trials of chromium ...

  9. 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

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

    OpenAIRE

    Bagdon, R E; Hazen, R E

    1991-01-01

    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 hr after application. Ultrastructural investigations showed that hexavalent chromium localized...

  11. BIOSORPTION OF CHROMIUM (VI) FROM INDUSTRIAL EFFLUENT BY WILD ANDMUTANT TYPE STRAIN OF SACCHAROMYCES CEREVISIAE AND ITS IMMOBILIZED FORM

    OpenAIRE

    K Selvam, K Arungandhi, B Vishnupriya, T Shanmuga priya and M Yamuna

    2013-01-01

    Biosorption of chromium was studied by wild type Saccharomyces cerevisiae strain, mutant strain, immobilized-wild type and mutant strain. Chromium absorption pattern was observed in all experimental conditions. Hexavalent chromium (VI) was analyzed by diphenyl carbazide method, by oxidizing the trivalent chromium (III). The percentage efficiency of wild type S. cerevisiae and its mutant strain, immobilized-wild type and mutant strain were 94.8%, 98.7%, 97.4% and 100% respectively. S. cerevisi...

  12. O impacto do crômio nos sistemas biológicos The impact of chromium on biological systems

    OpenAIRE

    Alba Denise de Queiroz Ferreira

    2002-01-01

    The impact of biological chromium's activity may be beneficial or not. This review presents the most relevant chemical aspects of these "two faces" of chromium by covering first, the efforts toward a clearer understanding of the carcinogenic properties of chromium compounds. The biomimetic chemistry of Cr(V) complexes illustrates the interactions of the intermediates formed by Cr(VI) reduction with DNA or oligonucleotides. The importance of trivalent chromium as an essential element is also e...

  13. [Effect of food diet supplements with chromium on the clinical and metabolic parameters in type 2 diabetic patients].

    Science.gov (United States)

    Sharafetdinov, Kh Kh; Meshcheriakova, V A; Plotnikova, O A; Mazo, V K; Gmoshinskiĭ, I V; Nechaeva, S V

    2004-01-01

    It was investigated the influence of food diet supplements with chromium on dynamic of glycaemia, lipid profile, blood pressure and weight in type 2 diabetic patients. Traditional hypocaloric diet was supplemented with chromium-spirulina (50 mcg chromium per day). The results investigations indicated that a chromium-enriched diet has beneficial effects on basal and postprandial glycaemia, the content of cholesterol and triglycerides in serum in compared with a traditional hypocaloric diet. PMID:15754482

  14. Thermal stabilization of chromium(VI) in kaolin.

    Science.gov (United States)

    Wei, Yu-Ling; Chiu, Shu-Yuan; Tsai, Hsien-Neng; Yang, Yaw-Wen; Lee, Jyh-Fu

    2002-11-01

    Reduction of Cr(VI) by heating may be a useful detoxification mechanism for thermal immobilization. Using X-ray absorption spectroscopy, the change of speciation of chromium in 105 degrees C dried 3.7% Cr(VI)-sorbed kaolin further heated at 500, 900, or 1100 degrees C was studied. The 105 degrees C dried 3.7% Cr(VI)-sorbed kaolin sample was prepared by mixing 1.5 L of 0.257 M CrO3 solution (pH 0.71) with 0.5 kg of kaolin powder for 48 h, and then the slurry was heated (dried) at 105 degrees C until a constant weight was reached. The toxicity characteristic leaching procedure method was used to determine the percentage of leached chromium from all heated samples. In all 500-900 degrees C heated Cr(VI)-sorbed kaolin samples, Cr2O3 transformed from the hydrated Cr(VI) by a 4-h heat application was identified by the X-ray absorption near edge structure and extended X-ray absorption fine structure (EXAFS) spectroscopy as the key species that is leaching-resistant due to its low solubility. For the 1100 degrees C heated Cr(VI)-sorbed kaolin sample, the Fourier transform of its EXAFS spectrum indicates that the intensity of the peaks at 2.45 (Cr-Cr shell of Cr2O3) and 5.00 A (Cr-Cr and Cr-O shells of Cr2O3) without phase shift correction is either relatively smaller or disappearing, compared with that of the 500-900 degrees C heated Cr(VI)-sorbed kaolin samples. It is suggested that chromium octahedra were bridged to silica tetrahedra and incorporated in minerals formed at 1100 degrees C, such as mullite or sillimanite, since these phases were detected by XRD. Cr of this form is not easily leached. PMID:12433175

  15. Evaluation of chromium concentration in cattle feces using different acid digestion and spectrophotometric quantification techniques

    Directory of Open Access Journals (Sweden)

    N.K.P. Souza

    2013-10-01

    Full Text Available The objective of this work was to evaluate combinations between acid digestion techniques and spectrophotometric quantification to measure chromium concentration in cattle feces. Digestion techniques were evaluated based on the use of nitric and perchloric acids, sulfuric and perchloric acids, and phosphoric acid. The chromium quantification in the solutions was performed by colorimetry and by atomic absorption spectrophotometry (AAS. When AAS was used, the addition of calcium chloride to the solutions as a releasing agent was also evaluated. Several standard samples containing known chromium contents were produced (0, 2, 4, 6, 8 and 10g of chromium per kg of feces using cattle feces obtained from three different animals to evaluate the accuracy of the different combinations of techniques. The accuracy was evaluated by adjusting a simple linear regression model of the estimated values on the actual values of chromium content in the standard samples. Regardless of the digestion technique, the chromium content estimates in the standard samples obtained by colorimetry were not accurate (P0.05. The use of the digestion technique in phosphoric acid provided incomplete recovery of the fecal chromium (P0.05 fecal chromium contents.

  16. TOXICITY OF TRIVALENT CHROMIUM TO EARLY LIFE STAGES OF STEELHEAD TROUT

    Science.gov (United States)

    Acute and early life stage toxicity tests were conducted with trivalent chromium and steelhead trout (Salmo gairdneri). A 96-h LC50 of 4,400 micrograms/l chromium was obtained with two-month-old juvenile fish. Early life stage exposure from newly fertilized eggs to 30-d post-swim...

  17. Chromium trace determination in inorganic, organic and aqueous samples with isotope dilution mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Goetz, A.; Heumann, K.G.

    1988-06-01

    It is shown that chromium traces in different inorganic, organic and aqueous samples can be determined over a wide concentration range with isotope dilution mass spectrometry. Electrolytic or chromatographic isolation steps are added to a system of sample preparation units for oligo-element determinations to analyse chromium besides other heavy metals. The isotope ratio /sup 52/Cr//sup 53/Cr is measured in a thermal quadrupole mass spectrometer using a single-filament ion source with additions of silica gel and boric acid. In water samples, which contain humic substances, chromium concentrations of a few ng/g and less can be determined with relative standard deviations of about 1% and better. A differentiation is possible into the total chromium content and into chromium species which carry out isotope exchange reactions and those which are inert for an isotope exchange reaction. The chromium concentrations of four standard reference materials (two plants BCR 60 and 61, one tissue BCR 278, one sewage sludge BCR 144), which are not certified for chromium, are determined to be 29.4 ..mu..g/g, 534 ..mu..g/g, 0.78 ..mu..g/g, and 466.1 ..mu..g/g, respectively. In three different sediments total chromium concentrations between 100 ..mu..g/g and 180 ..mu..g/g are analysed with relative standard deviations of 0.6%-1.2%.

  18. Assessment of chromium contamination in the Monte Alegre stream: a case study

    OpenAIRE

    Juliano José Corbi; Felipe André dos Santos; Ricardo Zerlin; Ademir dos Santos; Claudio Gilberto Froehlich; Susana Trivinho-Strixino

    2011-01-01

    The aim of this work was to study the contamination by chromium in the sediments of the Monte Alegre stream and in the larvae of Odonata and the possible impact caused by them on the stream macroinvertebrates community. It was found that chromium contaminated the sediments and the aquatic biota. Although, the stream macroinvertebrates community structure did not appear to be modified.

  19. The impact of humic acid on chromium phytoextraction by aquatic macrophyte Lemna minor.

    Science.gov (United States)

    Kalčíková, Gabriela; Zupančič, Marija; Jemec, Anita; Gotvajn, Andreja Žgajnar

    2016-03-01

    Studies assessing chromium phytoextration from natural waters rarely consider potential implications of chromium speciation in the presence of ubiquitous humic substances. Therefore, the present study investigated the influence of environmentally relevant concentration of humic acid (TOC = 10 mg L(-1)) on chromium speciation (Cr = 0.15 mg L(-1)) and consequently on phytoextraction by aquatic macrophyte duckweed Lemna minor. In absence of humic acid, only hexavalent chromium was present in water samples and easily taken up by L. minor. Chromium uptake resulted in a significant reduction of growth rate by 22% and decrease of chlorophyll a and chlorophyll b contents by 48% and 43%, respectively. On the other hand, presence of humic acid significantly reduced chromium bioavailability (57% Cr uptake decrease) and consequently it did not cause any measurable effect to duckweed. Such effect was related to abiotic reduction of hexavalent chromium species to trivalent. Hence, findings of our study suggest that presence of humic acid and chromium speciation cannot be neglected during phytoextraction studies. PMID:26766370

  20. 76 FR 71926 - Defense Federal Acquisition Regulation Supplement: Applicability of Hexavalent Chromium Policy to...

    Science.gov (United States)

    2011-11-21

    ... Acquisition Regulation Supplement: Applicability of Hexavalent Chromium Policy to Commercial Items (DFARS Case... hexavalent chromium. DATES: Comment Date: Comments on the proposed rule should be submitted in writing to the.... SUPPLEMENTARY INFORMATION: I. Background DoD published a final rule at in the Federal Register at 76 FR 25569...

  1. 77 FR 39141 - Defense Federal Acquisition Regulation Supplement: Applicability of Hexavalent Chromium Policy to...

    Science.gov (United States)

    2012-06-29

    ... Acquisition Regulation Supplement: Applicability of Hexavalent Chromium Policy to Commercial Items (DFARS Case... material containing hexavalent chromium. DATES: Effective Date: June 29, 2012. FOR FURTHER INFORMATION... published a final rule (DFARS Case 2009-D004) in the Federal Register at 76 FR 25569 on May 5, 2011,...

  2. 75 FR 69064 - Draft Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the...

    Science.gov (United States)

    2010-11-10

    ... AGENCY Draft Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the... period on September 30, 2010 (75 FR 60454) for the external review draft human health assessment titled, ``Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the Integrated...

  3. 75 FR 18041 - Defense Federal Acquisition Regulation Supplement; Minimizing Use of Hexavalent Chromium (DFARS...

    Science.gov (United States)

    2010-04-08

    ... Supplement; Minimizing Use of Hexavalent Chromium (DFARS Case 2009-D004) AGENCY: Defense Acquisition... requirements for minimizing the use of hexavalent chromium in defense weapon systems, subsystems, components, and other items. The proposed rule prohibits the delivery of items containing hexavalent...

  4. A routine chromium determination in biological materials; application to various reference materials and standard reference materials

    International Nuclear Information System (INIS)

    The determination limit under standard working conditions of chromium in biological materials is discussed. Neutron activation analysis and atomic spectrometry have been described for some analytical experiences with NBS SRM 1577 reference material. The chromium determination is a part of a larger multi-element scheme for the determination of 12 elements in biological materials

  5. Toxicity assessment and geochemical model of chromium leaching from AOD slag.

    Science.gov (United States)

    Liu, Bao; Li, Junguo; Zeng, Yanan; Wang, Ziming

    2016-02-01

    AOD (Argon Oxygen Decarburization) slag is a by-product of the stainless steel refining process. The leaching toxicity of chromium from AOD slag cannot be ignored in the recycling process of the AOD slag. To assess the leaching toxicity of the AOD slag, batch leaching tests have been performed. PHREEQC simulations combined with FactSage were carried out based on the detailed mineralogical analysis and petrophysical data. Moreover, Pourbaix diagram of the Cr-H2O system was protracted by HSC 5.0 software to explore the chromium speciation in leachates. It was found that AOD slag leachate is an alkaline and reductive solution. The Pourbaix diagram of the Cr-H2O system indicated that trivalent chromium, such as Cr(OH)4(-), is the major chromium species in the experimental Eh-pH region considered. However, toxic hexavalent chromium was released with maximum concentrations of 30 µg L(-1) and 18 µg L(-1) at L/S 10 and 100, respectively, during the earlier leaching stage. It concluded that the AOD slag possessed a certain leaching toxicity. After 10 d of leaching, trivalent chromium was the dominant species in the leachates, which corresponded to the results of PHREEQC simulation. Leaching toxicity of AOD slag is based on the chromium speciation and its transformation. Great attention should be focused on such factors as aging, crystal form of chromium-enriched minerals, and electrochemical characteristics of the leachates. PMID:26583286

  6. Determination of hexavalent chromium in cosmetic products by ion chromatography and postcolumn derivatization.

    Science.gov (United States)

    Kang, Eun Kyung; Lee, Somi; Park, Jin-Hee; Joo, Kyung-Mi; Jeong, Hye-Jin; Chang, Ih Seop

    2006-05-01

    Chromium hydroxide green [Cr(2)O(OH)(4)] and chromium oxide green (Cr(2)O(3)) are colouring agents for use in cosmetic products. These colourants may contain chromium (VI), which cause skin allergies through percutaneous adsorption on the skin. Eye shadow is a representative cosmetic product in which significant colourants are used. We analysed the chromium (VI) in the eye shadows by ion chromatography and post column derivatization. We optimize conditions of chromium (VI) analysis in eye shadows. During the pretreatment procedure, there are no exchange of chromium (III) to chromium (VI). This method has a limit of quantification for chromium (VI) of 1.0 microg l(-1), recovery rate of 100 +/- 3% and analysis time less than 10 min. This result is 300 times more sensitive than the high-performance liquid chromatography method. We applied the optimized method to analyse 22 eye shadows and 6 colouring agents. 2 out of 22 of the products contained more than 5 mg l(-1). In our previous work, 5 mg l(-1) of Cr represented a threshold level. There was much more Cr(VI) in the colouring agents. The Cr(VI) in one of the colouring agents was 97.6 mg l(-1). PMID:16689807

  7. Chromium(III) Based Ziegler-Natta Catalysts for Olefin Polymerization

    International Nuclear Information System (INIS)

    Four chromium based oxo-trinuclear carboxylate complexes were prepared by reacting chromium(III) nitrate nonahydrate with acetic acid and substituted carboxylic acids. They were characterized using infrared spectroscopy (FT-IR). Chromium content of the complexes was determined by titrimetry method. The chromium(III) monochloroacetate complex, [Cr3O(ClCH2COO)6.3H2O]NO3.3H2O in combination with diethylaluminium chloride formed heterogeneous catalyst system for ethylene polymerization. Both Al/ Cr ratio and temperature influenced the catalytic activity. The maximum activity was 1768 gPE/ gCr/ hr/ atm, achieved by polymerizing at 29 degree Celsius and monomer pressure around 1 atm, with Al/ Cr ratio 30.8. Effect of chloro-substituent groups on carboxylic ligand was studied by comparing the catalytic activities of chromium(III) monochloroacetate, chromium(III) dichloroacetate, chromium(III) trichloroacetate and chromium(III) acetate.The polymerization reaction was found to be first order with respect to the monomer during the initial stage. The activity decreases very rapidly presumably due to fast decay of the active sites. The polyethylene was characterized using FT-IR and DSC, and the results showed that it was of high density and crystallinity. (author)

  8. Isolation and characterization of chromium-resistant bacteria from tannery effluents

    Energy Technology Data Exchange (ETDEWEB)

    Basu, M.; Bhattacharya, S.; Paul, A.K. [Univ. of Calcutta (India)

    1997-04-01

    Chromium (Cr), a transition metal, is one of the major sources of environmental pollution. It is discharged into the environment through the disposal of wastes from industries like leather tanning, metallurgical and metal finishing, textiles and ceramics, pigment and wood preservatives, photographic sensitizer manufacturing, etc. In the environment chromium occurs mainly in trivalent and hexavalent forms. The hexavalent chromium (Cr{sup 6+}) compounds are comparatively much more toxic than those of trivalent chromium (Cr{sup 3+}). The reason for such toxicity appears to be due to its rapid permeability through biological membranes and subsequent interaction with intracellular proteins and nucleic acids. The tanning industry, which commonly utilizes {open_quotes}chrome liquor{close_quotes} in the tanning process, discharges the effluents into the environment containing chrome salts in excess of the maximum permissible limits. Sludge deposition from such effluents, therefore, provides a natural environment for enrichment of chromium-resistant bacteria. Chromium-resistant microorganisms from such chromium-contaminated sediments have been isolated by several investigators. The present study was an attempt to evaluate the status of chromium-resistant bacteria in the tannery effluent sediments of Calcutta-based tanning industries. 14 refs., 2 figs., 6 tabs.

  9. Chromium supplementation enhances the metabolic response of steers to lipopolysaccharide (LPS) challenge

    Science.gov (United States)

    The effect of chromium (Cr; KemTRACE®brandChromiumProprionate 0.04%, Kemin Industries) supplementation on the metabolic response to LPS challenge was examined. Steers (n=20; 235±4 kg body weight (BW)) received a premix that added 0 (Con) or 0.2 mg/kg Cr to the total diet (DM (dry matter) basis) for ...

  10. Chromium supplementation alters the performance, metabolism, and immune response of feedlot cattle during the receiving period

    Science.gov (United States)

    Crossbreed steers (n = 180; 507 +/- 13 lb) were fed during a 56-d receiving period to determine if supplementing chromium (Cr; KemTRACEbrandChromiumPropionate 0.04%, Kemin Industries) would improve feedlot performance and health of newly received cattle. A completely randomized block design (36 pens...

  11. 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.

  12. Insulin Resistance and Body Weight: Recent Human Studies Documenting the Benefits of Supplemental Chromium

    Science.gov (United States)

    The essentiality of chromium for humans was confirmed more than three decades ago with the studies showing that patients on total parenteral nutritrion (TPN) developed severe diabetic-like symptoms that could be reversed by the addition of chromium to their parenteral nutrition solutions. Since the...

  13. Chromium stress induced alterations in biochemical and enzyme metabolism in aquatic and terrestrial plants.

    Science.gov (United States)

    Ganesh, K Sankar; Baskaran, L; Rajasekaran, S; Sumathi, K; Chidambaram, A L A; Sundaramoorthy, P

    2008-06-01

    Water is seriously polluted by the discharge of various industrial wastewater containing heavy metals. Among them, chromium is considered to be toxic to living organisms and it is released mostly from tanneries. The chromium-contaminated water is discharged into nearby water bodies and it affects both aquatic and terrestrial plants. So the present experiment was conducted with an aquatic plant, water lettuce (Pistia stratiotes L.) and a terrestrial plant soybean (Glycine max L. Merr.). They were treated with different concentrations (0, 5, 10, 25, 50, 100 and 200mg/L) of potassium dichromate solution. The biochemical parameters such as total chlorophyll, carotenoid, protein and amino acid content and the enzymatic activities like catalase and peroxidase were estimated. The accumulation of chromium was also analysed in both the plants. All the biochemical contents and enzyme activities of water lettuce and soybean seedlings showed a great variation with respect to the increase in chromium concentrations. The accumulation of chromium increased gradually with the increase of chromium concentrations. Total inhibition of all the parameters were observed at 300 mg/L chromium concentration. The terrestrial plant soybean was sensitive than the aquatic plant water lettuce towards chromium stress. PMID:18206355

  14. Effects of vitamins on chromium(VI)-induced damage.

    OpenAIRE

    Sugiyama, M

    1991-01-01

    The effects of vitamin E and vitamin B2 on DNA damage and cellular reduction of chromium(VI) were investigated using Chinese hamster V-79 cells. Pretreatment with alpha-tocopherol succinate (vitamin E) resulted in a decrease of DNA single-strand breaks produced by Na2CrO4, while similar treatment with riboflavin (vitamin B2) enhanced levels of DNA breaks. In contrast, levels of DNA-protein crosslinks induced by Na2CrO4 were unaffected by these vitamins. Electron spin resonance (ESR) studies s...

  15. Retention of chromium by modified Al-Bentonite

    OpenAIRE

    Volzone C.; Garrido L. B.

    2002-01-01

    Retention of chromium (III) from a tanning wastewater by modified Al-bentonites was studied. One bentonite from San Juan province, Argentina, was used. Al-bentonite was prepared by contact of bentonite with hydrolyzed OH-Al solutions (0.10 M in Al) for 24 hours. The modified Al-bentonites were obtained by: a) treatment with 0.5 M sodium chloride; b) with 0.5 M sodium chloride adjusted at pH 8; and c) treatment with an hexametaphosphate solution after sodium addition. Then, the samples were dr...

  16. Study on anaerobic treatment of wastewater containing hexavalent chromium*

    OpenAIRE

    Xu, Yan-Bin; Xiao, Hua-hua; Sun, Shui-yu

    2005-01-01

    A self-made anaerobic bio-filter bed which was inoculated with special sludge showed high efficiency in removing hexavalent chromium. When pump flow was 47 ml/min and CODCr of wastewater was about 140 mg/L, it took 4 h to decrease the Cr6+ concentrations from about 60 mg/L to under 0.5 mg/L, compared with 14 h without carbon source addition. Cr6+ concentrations ranged from 64.66 mg/L to 75.53 mg/L, the system efficiency was excellent. When Cr6+ concentration reached 95.47 mg/L, the treatment ...

  17. Chromium Renderserver: Scalable and Open Source Remote RenderingInfrastructure

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Brian; Ahern, Sean; Bethel, E. Wes; Brugger, Eric; Cook,Rich; Daniel, Jamison; Lewis, Ken; Owen, Jens; Southard, Dale

    2007-12-01

    Chromium Renderserver (CRRS) is software infrastructure thatprovides the ability for one or more users to run and view image outputfrom unmodified, interactive OpenGL and X11 applications on a remote,parallel computational platform equipped with graphics hardwareaccelerators via industry-standard Layer 7 network protocolsand clientviewers. The new contributions of this work include a solution to theproblem of synchronizing X11 and OpenGL command streams, remote deliveryof parallel hardware-accelerated rendering, and a performance analysis ofseveral different optimizations that are generally applicable to avariety of rendering architectures. CRRSis fully operational, Open Sourcesoftware.

  18. Chromium Doped ZnS Nanostructures: Structural and Optical Characteristics

    Science.gov (United States)

    Gogoi, D. P.; Das, U.; Ahmed, G. A.; Mohanta, D.; Choudhury, A.; Stanciu, G. A.

    2009-06-01

    Chromium doped ZnS nanoparticles arranged in the form of fractals were fabricated by using inexpensive physico-chemical route. The Cr:ZnS samples were characterized by diffraction and spectroscopic techniques. Unexpected growth of fractals with several micrometer dimensions and of core size 1 μm (tip to tip) was confirmed through TEM micrographs. At higher magnification, we found that individual fractals consist of spherical nanoparticles of average size leading to such organized structures describing fractal pattern is encountered in this work.

  19. Alkaline stress corrosion of iron-nickel-chromium austenitic alloys

    International Nuclear Information System (INIS)

    This research thesis reports the study of the behaviour in stress corrosion of austenitic iron-nickel-chromium alloys by means of tensile tests at imposed strain rate, in a soda solution at 50 pc in water and 350 degrees C. The author shows that the mechanical-chemical model allows the experimental curves to be found again, provided the adjustment of characteristic parameters, on the one hand, of corrosion kinetics, and on the other hand, of deformation kinetics. A classification of the studied alloys is proposed

  20. Structural, morphological and optical properties of chromium oxide nanoparticles

    Science.gov (United States)

    Babukutty, Blessy; Parakkal, Fasalurahman; Bhalero, G. M.; Aravind, P. B.; Nair, Swapna S.

    2015-06-01

    Chromium oxide nanoparticles are synthesized by reduction route from chloride precursors with surfactant, trioctylphosphine oxide (TOPO). Structural and morphological characterization are analyzed using X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Transmission Electron micrographs show that the average grain size lies in the range 5nm to 10nm. Optical characterization has been done by UV-VIS spectrophotometer. Distinct optical absorptions of Cr3+ ions show hinting towards the presence of Cr2O3. Presence of oxygen is also confirmed from Electron Energy Loss Spectroscopy (EELS) studies.

  1. Structural, morphological and optical properties of chromium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Babukutty, Blessy; Parakkal, Fasalurahman; Nair, Swapna S., E-mail: swapna.s.nair@gmail.com [School of Mathematical and Physical Sciences, Department of Physics, Central University of Kerala, Kasaragod 671314 (India); Bhalero, G. M. [UGC-DAE, IGCAR, Kalpakkam, TamilNadu (India); Aravind, P. B. [Cochin University of Science and Technology(CUSAT), Cochin (India)

    2015-06-24

    Chromium oxide nanoparticles are synthesized by reduction route from chloride precursors with surfactant, trioctylphosphine oxide (TOPO). Structural and morphological characterization are analyzed using X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Transmission Electron micrographs show that the average grain size lies in the range 5nm to 10nm. Optical characterization has been done by UV-VIS spectrophotometer. Distinct optical absorptions of Cr{sup 3+} ions show hinting towards the presence of Cr{sub 2}O{sub 3}. Presence of oxygen is also confirmed from Electron Energy Loss Spectroscopy (EELS) studies.

  2. A mortality study of nickel/chromium platers.

    OpenAIRE

    Sorahan, T; Burges, D. C.; Waterhouse, J. A.

    1987-01-01

    The mortality experienced by a cohort of 2689 nickel/chromium platers between 1946 and 1983 has been investigated. All members of the study cohort had some period of chrome exposed employment. Overall, compared with the general population of England and Wales, statistically significant differences relating to cancer were found for cancer of the stomach (E = 16.2, O = 25), primary cancer of the liver (E = 0.8, O = 4), cancer of the nose and nasal cavities (E = 0.3, O = 3), cancers of the lung ...

  3. Structural, morphological and optical properties of chromium oxide nanoparticles

    International Nuclear Information System (INIS)

    Chromium oxide nanoparticles are synthesized by reduction route from chloride precursors with surfactant, trioctylphosphine oxide (TOPO). Structural and morphological characterization are analyzed using X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Transmission Electron micrographs show that the average grain size lies in the range 5nm to 10nm. Optical characterization has been done by UV-VIS spectrophotometer. Distinct optical absorptions of Cr3+ ions show hinting towards the presence of Cr2O3. Presence of oxygen is also confirmed from Electron Energy Loss Spectroscopy (EELS) studies

  4. Chromium removal by zeolite-rich materials obtained from an exhausted FCC catalyst: Influence of chromium incorporation on the sorbent structure.

    Science.gov (United States)

    Gonzalez, Maximiliano R; Pereyra, Andrea M; Torres Sánchez, Rosa M; Basaldella, Elena I

    2013-10-15

    A spent FCC catalyst was converted into a zeolitic mixture, and the product obtained was afterward used as trapping material for Cr(III) species frequently found in aqueous solutions. Eventual changes in the sorbent structure produced by Cr incorporation were studied by different characterization techniques such as point of zero charge determinations (PZC), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and infrared absorption (FTIR). The XRD and FTIR analyses indicated that chromium incorporation produces an amorphization of the material, and PZC measurements show no surface adsorption of charged chromium species. SEM and EDX analyses clearly show that after chromium sorption, the initial microspheroidal catalyst morphology was maintained, and the presence of chromium species was mainly detected in the outer microsphere surface, where the zeolite crystals were hydrothermally grown. PMID:23910499

  5. 40 CFR Appendix A to Part 419 - Processes Included in the Determination of BAT Effluent Limitations for Total Chromium...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Processes Included in the Determination of BAT Effluent Limitations for Total Chromium, Hexavalent Chromium, and Phenolic Compounds (4AAP) A...—Processes Included in the Determination of BAT Effluent Limitations for Total Chromium, Hexavalent...

  6. Verification and Validation of RADTRAN 5.5.

    Energy Technology Data Exchange (ETDEWEB)

    Osborn, Douglas.; Weiner, Ruth F.; Mills, George Scott; Hamp, Steve C.

    2005-02-01

    This document contains a description of the verification and validation process used for the RADTRAN 5.5 code. The verification and validation process ensured the proper calculational models and mathematical and numerical methods were used in the RADTRAN 5.5 code for the determination of risk and consequence assessments. The differences between RADTRAN 5 and RADTRAN 5.5 are the addition of tables, an expanded isotope library, and the additional User-Defined meteorological option for accident dispersion. 3

  7. GPR55: a new member of the cannabinoid receptor clan?

    OpenAIRE

    Pertwee, R. G.

    2007-01-01

    In this issue of the British Journal of Pharmacology, Ryberg et al. present convincing in vitro evidence that the orphan GPCR, GPR55, is a cannabinoid receptor. GPR55 was activated by a range of plant, synthetic and endogenous cannabinoids and blocked by the non-psychoactive phytocannabinoid, cannabidiol. Their experiments have revealed several differences between the pharmacology of GPR55 and the established cannabinoid CB1 and CB2 receptors. For example, the CB1 receptor antagonist, AM251, ...

  8. Effect of recasting on the elastic modulus of metal-ceramic systems from nickel-chromium and cobalt-chromium alloys

    OpenAIRE

    Mirković Nemanja

    2007-01-01

    Background/Aim. Elastic modulus of metal-ceramic systems determines their flexural strength and prevents damages on ceramics during mastication. Recycling of basic alloys is often a clinical practice, despite the possible effects on the quality of the future metal-ceramic dentures. This research was done to establish recasting effects of nickel-chromium and cobalt-chromium alloys on the elastic modulus of metalceramic systems in making fixed partial dentures. Methods. The research was perform...

  9. 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

    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...... at 0.5 ppm without interference from other pure metals, alloys, or leather. A market survey using the test showed no chromium(VI) release from work tools (0/100). However, chromium(VI) release from metal screws (7/60), one earring (1/50), leather shoes (4/100) and leather gloves (6/11) was observed...

  10. The correlation between swelling and radiation-induced segregation in iron-chromium-nickel alloys

    International Nuclear Information System (INIS)

    The magnitudes of both void swelling and radiation-induced segregation (RIS) in iron-chromium-nickel alloys are dependent on bulk alloy composition. Because the diffusivity of nickel via the vacancy flux is slow relative to chromium, nickel enriches and chromium depletes at void surfaces during irradiation. This local composition change reduces the subsequent vacancy flux to the void, thereby reducing void swelling. In this work, the resistance to swelling from major element segregation is estimated using diffusivities derived from grain boundary segregation measurements in irradiated iron-chromium-nickel alloys. The resistance to void swelling in iron- and nickel-base alloys correlates with the segregation and both are functions of bulk alloy composition. Alloys that display the greatest amount of nickel enrichment and chromium depletion are found to be most resistant to void swelling, as predicted. Additionally, swelling is shown to be greater in alloys in which the RIS profiles are slow to develop

  11. Development of Alkaline Oxidative Dissolution Methods for Chromium (III) Compounds Present in Hanford Site Tank Sludges

    Energy Technology Data Exchange (ETDEWEB)

    NN Krot; VP Shilov; AM Fedoseev; NA Budantseva; MV Nikonov; AB Yusov; AYu Garnov; IA Charushnikova; VP Perminov; LN Astafurova; TS Lapitskaya; VI Makarenkov

    1999-07-02

    The high-level radioactive waste sludge in the underground storage tanks at the Hanford Site contains various chromium(III)solid phases. Dissolution and removal of chromium from tank waste sludges is desirable prior to high-level waste vitrification because increased volume is required to incorporate the residual chromium. Unfortunately, dissolution of chromium from the sludge to form Cr(OH){sub 4}{sup {minus}} through treatment with heated NaOH solution (also used to dissolve aluminum phases and metathesize phosphates to sodium salts) generally has been unsuccessful in tests with both simulated and genuine Hanford waste sludges. Oxidative dissolution of the Cr(III) compounds to form soluble chromate has been proposed as an alternative chromium solid phase dissolution method and results of limited prior testing have been reported.

  12. Unconventional drop in the electrical resistance of chromium metal thin films at low temperature

    Science.gov (United States)

    Ohashi, M.; Ohashi, K.; Sawabu, M.; Miyagawa, M.; Kubota, T.; Takanashi, K.

    2016-09-01

    We studied the electrical resistance of single-crystal and polycrystalline chromium films. The ρ (T) curve of single-crystal films decrease with decreasing temperature and show humps at around 300 K consistent with the bulk chromium being an itinerant antiferromagnet. In the polycrystalline films, on the other hand, the ρ (T) curves deviate from those of the bulk chromium. Moreover, we observed sudden decrease in the resistance around 1.5 K. Although previous studies suggested that chromium films become superconductive (Schmidt et al. (1972) [12]), it is difficult to conclude whether a superconducting transition occurs because the electrical resistivity is not zero in all films. No anomaly was detected by resistance measurements around room temperature, and the sudden decrease in the resistance at low temperature may be attributed to the suppression of antiferromagnetic interaction by thinning down the chromium element.

  13. Special features of joint chromium and molybdenum electrocrystallization surface morphology of physicomechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Vashchenko, S.V.; Adzhiev, B.U.; Solov' eva, Z.A.

    1987-10-01

    The authors studied the effect of molybdenum on the surface structure and certain physicomechanical properties of the electrolytic chromium produced by Cr-Mo electrodeposition from CrO/sub 3/ solutions with added SO/sub 4//sup 2 -/ and SiF/sub 6//sup 2 -/ ions. The results indicate that the changes in hardness, hydrogenation, and internal stresses of the chromium coatings which occur upon alloying with molybdenum are chiefly due to structural changes, while the incorporation of Mo into chromium by itself does not markedly affect these characteristics. The structural changes of chromium which occur following the codeposition of molybdenum evidently are due, not only to a change in the relative concentration of anions in the cathodic film, particularly a decrease in the content of catalytic anions in the film, but also to special features in chromium electrocrystallization, an aspect which requires special consideration involving methods of investigating fine structure and surface composition.

  14. Role of the lysophosphatidylinositol/GPR55 axis in cancer.

    Science.gov (United States)

    Falasca, Marco; Ferro, Riccardo

    2016-01-01

    Lysophosphatidylinositol (LPI) is a well-known bioactive lipid that is able to activate signalling cascades relevant to cell proliferation, migration, survival and tumourigenesis. It is well-established that the G protein-coupled receptor 55 (GPR55) is the specific receptor for LPI. Several investigations have demonstrated that the signalling pathways activated by LPI through its receptor GPR55 play a pivotal role in different cancer type. This review focuses on the role of the LPI/GPR55 axis, in particular with regards to its pharmacological potential therapeutic exploitation. PMID:26588872

  15. Removal of toxic chromium from wastewater using green alga Ulva lactuca and its activated carbon

    International Nuclear Information System (INIS)

    Biosorption of heavy metals can be an effective process for the removal of toxic chromium ions from wastewater. In this study, the batch removal of toxic hexavalent chromium ions from aqueous solution, saline water and wastewater using marine dried green alga Ulva lactuca was investigated. Activated carbon prepared from U. lactuca by acid decomposition was also used for the removal of chromium from aqueous solution, saline water and wastewater. The chromium uptake was dependent on the initial pH and the initial chromium concentration, with pH ∼1.0, being the optimum pH value. Langmuir, Freundlich, Redlich-Peterson and Koble-Corrigan isotherm models were fitted well the equilibrium data for both sorbents. The maximum efficiencies of chromium removal were 92 and 98% for U. lactuca and its activated carbon, respectively. The maximum adsorption capacity was found to be 10.61 and 112.36 mg g-1 for dried green alga and activated carbon developed from it, respectively. The adsorption capacities of U. lactuca and its activated carbon were independent on the type of solution containing toxic chromium and the efficiency of removal was not affected by the replacing of aqueous solution by saline water or wastewater containing the same chromium concentration. Two hours were necessary to reach the sorption equilibrium. The chromium uptake by U. lactuca and its activated carbon form were best described by pseudo second-order rate model. This study verifies the possibility of using inactivated marine green alga U. lactuca and its activated carbon as valuable material for the removal of chromium from aqueous solutions, saline water or wastewater

  16. Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) rod, bar, and wire

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) rod, bar, and wire

  17. Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nikel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) seamless pipe and tube

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nikel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) seamless pipe and tube

  18. Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045 and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) plate, sheet and strip

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045 and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) plate, sheet and strip

  19. Effects of chromium nanoparticle dosage on growth, body composition, serum hormones and tissue chromium in Sprague-Dawley rats*

    OpenAIRE

    Zha, Long-ying; Xu, Zi-Rong; Wang, Min-qi; Gu, Liang-ying

    2007-01-01

    This 6-week study was conducted to evaluate the effects of seven different levels of dietary chromium (Cr) (0, 75, 150, 300, 450, 600, and 1 200 ppb Cr) in the form of Cr nanoparticle (CrNano) on growth, body composition, serum hormones and tissue Cr in Sprague-Dawley (SD) rats. Seventy male SD rats (average initial body weight of (83.2±4.4) g) were randomly assigned to seven dietary treatments (n=10). At the end of the trial, body composition was assessed via dual energy X-ray absorptiometry...

  20. Boriding of high carbon high chromium cold work tool steel

    International Nuclear Information System (INIS)

    High-carbon high-chromium cold work tool steels are widely used for blanking and cold forming of punches and dies. It is always advantageous to obtain an increased wear resistant surface to improve life and performance of these steels. In this connection boriding of a high-carbon high-chromium cold work die steel, D3, was conducted in a mixture of 30 percentage B4C, 70 percentage borax at 950 degree C for two, four and six hours. Case depth of the borided layer obtained was between 40 to 80 micro m. After boriding, the surface hardness achieved was between 1430 to 1544 HV depending upon the process time. X-ray diffraction studies confirmed the formation of a duplex compound layer consisting of FeB and Fe2B. It is generally considered that FeB is undesirable because of its inherent brittleness. Post boriding treatment (homogenization) transformed the compound layer into single-phase layer of Fe2B, while surface hardness decreased to 1345-1430 HV. Pin-on-disc were test showed that wear resistance of the borided samples was superior as compared to non-borided material and increased with boriding time. (author)