Sputtered silver films to improve chromium carbide based solid lubricant coatings for use to 900 C

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher; Sliney, Harold E.; Deadmore, Daniel L.

1988-01-01

Thin silver films, 250 to 3500 A thick, were sputtered onto PS200, a plasma sprayed, chromium carbide based solid lubricant coating, to reduce run-in wear and improve tribological properties. The coating contains bonded chromium carbide as the wear resistant base stock with silver and barium fluoride/calcium fluoride eutectic added as low and high temperature lubricants respectively. Potential applications for the PS200 coating are cylinder wall/piston ring lubrication for Stirling engines and foil bearing journal lubrication. In this preliminary program, the silver film overlay thickness was optimized based on tests using a pin-on-disk tribometer. The friction and wear studies were performed in a helium atmosphere at temperatures from 25 to 760 C with a sliding velocity of 2.7 m/s under a 4.9 N load. Films between 1000 and 1500 A provide the best lubrication of the counterface material. The films enrich the sliding surface with lubricant and reduce the initial abrasiveness of the as ground, plasma-sprayed coating surface, thus reducing wear.

Studies on copper alloys containing chromium on the copper side phase diagram

NASA Technical Reports Server (NTRS)

Doi, T.

1984-01-01

Specimens were prepared from vacuum melted alloys of high purity vacuum melted copper and electrolytic chromium. The liquidus and eutectic point were determined by thermal analysis. The eutectic temperature is 1974.8 F and its composition is 1.28 wt% of chromium. The determination of solid solubility of chromium in copper was made by microscopic observation and electrical resistivity measurement. The solubility of chromium in solid copper is 0.6 wt% at 1050 F, 0.4 wt% at 1000 F, 0.25 wt% at 950 F, 0.17 wt% at 900 F, and 0.30 wt% at 840 F.

Diffusion of Chromium in Alpha Cobalt-Chromium Solid Solutions

NASA Technical Reports Server (NTRS)

Weeton, John W

1951-01-01

Diffusion of chromium in cobalt-chromium solid solutions was investigated in the range 0 to 40 atomic percent at temperatures of 1360 degrees, 1300 degrees, 1150 degrees, and 10000 degrees c. The diffusion coefficients were found to be relatively constant within the composition range covered by each specimen. The activation heat of diffusion was determined to be 63,000 calories per mole. This value agrees closely with the value of 63,400 calories per mole calculated by means of the Dushman-Langmuir equation.

Composition optimization of chromium carbide based solid lubricant coatings for foil gas bearings at temperatures to 650 C

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher

1987-01-01

A test program to determine the optimum composition of chromium carbide based solid lubricant coatings for compliant gas bearings is described. The friction and wear properties of the coatings are evaluated using a foil gas bearing test apparatus. The various coatings were prepared by powder blending, then plasma sprayed onto Inconel 718 test journals and diamond ground to the desired coating thickness and surface finish. The journals were operated against preoxidized nickel-chromium alloy foils. The test bearings were subjected to repeated start/stop cycles under a 14 kPa (2 psi) bearing unit load. The bearings were tested for 9000 start/stop cycles or until the specimen wear reached a predetermined failure level. In general, the addition of silver and eutectic to the chromium carbide base stock significantly reduced foil wear and increased journal coating wear. The optimum coating composition, PS212 (70 wt% metal bonded Cr3C2, 15 wt% Ag, 15% BaF2/CaF2 eutectic), reduced foil wear by a factor of two and displayed coating wear well within acceptable limits. The load capacity of the bearing using the plasma-sprayed coating prior to and after a run-in period was ascertained and compared to polished Inconel 718 specimens.

Coagulant from Leucaena leucocephala for Chromium Removal

NASA Astrophysics Data System (ADS)

Razak, N. H. Abd; Khairuddin, N.; Ismail, K. N.; Musa, M.

2018-05-01

This research investigated the effectiveness of leucaena leucocephala as a natural coagulant for chromium removal. Leucaena leucocephala is a permanent non-climbing shrub tree which is wild and abundant in Malaysia and commonly known as petai belalang. Coagulation experiment using jar test were performed where the effect of coagulant dosage and pH were examined. The parameters investigated were suspended solid (SS), chemical oxygen demand (COD), biological oxygen demand (BOD), turbidity and chromium content. The optimum of leucaena leucocephala coagulant dosage for removal of suspended solid, turbidity, COD, BOD and Chromium is at range 400-600 mg/L which yielded 45, 31.4, 38.5, 27.5 and 4.05% removal respectively. While the optimum pH is at pH 2-4 (acidic) which give 33.3, 26.8, 33.75, 31.4 and 14.06% removal of suspended solid, COD, BOD, turbidity and chromium content respectively. It is concluded that the leucaena leucocephala showed tremendous potential for chromium removal.

Soybean plant growth study conducted using purified protein hydrolysate-based fertilizer made from chrome-tanned leather waste.

PubMed

Pati, Anupama; Chaudhary, Rubina

2015-12-01

Leather processing discharges enormous amount of chrome containing leather solid waste which creates a major disposal problem. Chrome-tanned leather solid waste is a complex of collagen and chromium. The presence of chromium limits protein application in fertilizer industry. The purified protein hydrolysate with zero chromium could be used as a nitrogen source for fertilizer formulation. In this study, an attempt has been made to employ purified protein hydrolysate derived from chrome-tanned leather shavings (CTLS) in formulation of fertilizer. The formulated fertilizer (1–3 t ha(-1)) is employed as nitrogen source in production of soybean. Plant growth study demonstrates that formulated fertilizer dosage 3 t ha(-1) produced similar effects of commercial fertilizer-treated plants. Application of formulated fertilizer yielded higher seed in plant than commercial fertilizer.

The influence of precipitation kinetics on trace element partitioning between solid and liquid solutions: A coupled fluid dynamics/thermodynamics framework to predict distribution coefficients

NASA Astrophysics Data System (ADS)

Kavner, A.

2017-12-01

In a multicomponent multiphase geochemical system undergoing a chemical reaction such as precipitation and/or dissolution, the partitioning of species between phases is determined by a combination of thermodynamic properties and transport processes. The interpretation of the observed distribution of trace elements requires models integrating coupled chemistry and mechanical transport. Here, a framework is presented that predicts the kinetic effects on the distribution of species between two reacting phases. Based on a perturbation theory combining Navier-Stokes fluid flow and chemical reactivity, the framework predicts rate-dependent partition coefficients in a variety of different systems. We present the theoretical framework, with applications to two systems: 1. species- and isotope-dependent Soret diffusion of species in a multicomponent silicate melt subjected to a temperature gradient, and 2. Elemental partitioning and isotope fractionation during precipitation of a multicomponent solid from a multicomponent liquid phase. Predictions will be compared with results from experimental studies. The approach has applications for understanding chemical exchange in at boundary layers such as the Earth's surface magmatic systems and at the core/mantle boundary.

Tribological composition optimization of chromium-carbide-based solid lubricant coatings for foil gas bearings at temperatures to 650 C

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher

1988-01-01

The determination of the tribilogically optimum composition of chromium-carbide-based solid lubricant coatings using a foil gas bearing test apparatus is described. The coatings contain a wear resistant chromium carbide `base stock' with the lubricant additives silver and BaF2-CaF2 eutectic. The coating composition is optimized for air-lubricated foil gas bearings at temperatures ranging from 25 to 650 C. The various compositions were prepared by powder blending, then plasma sprayed onto Inconel 718 test journals and diamond ground to the desired coating thickness and surface finish. The journals were operated against preoxidized Ni-Cr alloy foils, and the test bearings were subjected to repeated start-stop cycles under a bearing unit of 14 kPa. Sliding contact between the coated journal and the smooth foil occurs during bearing start-up before lift-off or hydrodynamic lubrication by the air film and during bearing coast-down. The bearings were tested for 9000 start-stop cycles or until specimen reached a predetermined failure level.

Antioxidant-Based Eutectics of Irbesartan: Viable Multicomponent Forms for the Management of Hypertension.

PubMed

Haneef, Jamshed; Chadha, Renu

2018-04-01

The present research work highlights the development of multicomponent solid form of the antihypertensive drug irbesartan (IRB) to improve its biopharmaceutical attributes. Mechanochemical synthesis of a new solid form of IRB with coformers having antioxidant properties (syringic acid, nicotinic acid, and ascorbic acid) resulted into three eutectic mixtures (EMs). Formation of eutectic was ascertained by differential scanning calorimetry whereas exact stoichiometry (50/50% w/w) was established by phase diagram and Tamman's triangle. The strong homomeric interaction between individual components and steric hindrances is responsible for the eutectic formation. EMs exhibited superior apparent solubility (five- to nine fold) and significant enhancement in intrinsic dissolution rate (two- to three fold) as compared to the plain drug. In vivo pharmacokinetic and in vivo pharmacodynamic studies revealed a significant improvement in the biopharmaceutical performance of EMs. Marked protection against oxidative stress was observed in EMs over plain drug by controlling the level/activity of plasma H 2 O 2 and antioxidant enzymes (superoxide dismutase and catalase) in the kidney matrix of dexamethasone (Dexa)-induced hypertensive rats. Thus, these solid forms of IRB can serve as viable multicomponent forms to be translated into product development for better therapeutic efficacy in the management of hypertension.

Direct determination of chromium in infant formulas employing high-resolution continuum source electrothermal atomic absorption spectrometry and solid sample analysis.

PubMed

Silva, Arlene S; Brandao, Geovani C; Matos, Geraldo D; Ferreira, Sergio L C

2015-11-01

The present work proposed an analytical method for the direct determination of chromium in infant formulas employing the high-resolution continuum source electrothermal atomic absorption spectrometry combined with the solid sample analysis (SS-HR-CS ET AAS). Sample masses up to 2.0mg were directly weighted on a solid sampling platform and introduced into the graphite tube. In order to minimize the formation of carbonaceous residues and to improve the contact of the modifier solution with the solid sample, a volume of 10 µL of a solution containing 6% (v/v) H2O2, 20% (v/v) ethanol and 1% (v/v) HNO3 was added. The pyrolysis and atomization temperatures established were 1600 and 2400 °C, respectively, using magnesium as chemical modifier. The calibration technique was evaluated by comparing the slopes of calibration curves established using aqueous and solid standards. This test revealed that chromium can be determined employing the external calibration technique using aqueous standards. Under these conditions, the method developed allows the direct determination of chromium with limit of quantification of 11.5 ng g(-1), precision expressed as relative standard deviation (RSD) in the range of 4.0-17.9% (n=3) and a characteristic mass of 1.2 pg of chromium. The accuracy was confirmed by analysis of a certified reference material of tomato leaves furnished by National Institute of Standards and Technology. The method proposed was applied for the determination of chromium in five different infant formula samples. The chromium content found varied in the range of 33.9-58.1 ng g(-1) (n=3). These samples were also analyzed employing ICP-MS. A statistical test demonstrated that there is no significant difference between the results found by two methods. The chromium concentrations achieved are lower than the maximum limit permissible for chromium in foods by Brazilian Legislation. Copyright © 2015. Published by Elsevier B.V.

Characterization of low-dose doxorubicin-loaded silica-based nanocomposites

NASA Astrophysics Data System (ADS)

Prokopowicz, Magdalena

2018-01-01

In this study, we synthesized multicomponent solid films of low-dose doxorubicin (DOX)-loaded polydimethylsiloxane (PDMS)-SiO2/CaP nanocomposites via sol-gel process combined with the method of evaporation-induced self-assembly (EISA) at low temperature. Nanomechanical properties (elasticity and adhesion) of the synthesized multicomponent films were determined by using atomic force microscopy with a PeakForce™ quantitative nanomechanical mapping imaging technique. Solid state of DOX in the synthesized films was studied by using UV-vis and fluorescence spectroscopy. The release profile of different concentrations of DOX loaded (1, 3, and 5 wt%) on the multicomponent films was assessed using USP Apparatus 4 and via UV-vis end analysis. Results indicate drug-component interactions on the overall morphology of domains (size and shape), nanomechanical properties, and release behavior of the DOX-loaded nanocomposites. We observed a progressive increase in surface roughness and mean adhesive value with increasing concentration of DOX loaded (0-5 wt%). In addition, for all the different concentrations of DOX-loaded, we observed a diffusion-controlled drug release.

Development of Surface Complexation Models of Cr(VI) Adsorption on Soils, Sediments and Model Mixtures of Kaolinite, Montmorillonite, γ-Alumina, Hydrous Manganese and Ferric Oxides and Goethite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koretsky, Carla

Hexavalent chromium is a highly toxic contaminant that has been introduced into aquifers and shallow sediments and soils via many anthropogenic activities. Hexavalent chromium contamination is a problem or potential problem in the shallow subsurface at several DOE sites, including Hanford, Idaho National Laboratory, Los Alamos National Laboratory and the Oak Ridge Reservation (DOE, 2008). To accurately quantify the fate and transport of hexavalent chromium at DOE and other contaminated sites, robust geochemical models, capable of correctly predicting changes in chromium chemical form resulting from chemical reactions occurring in subsurface environments are needed. One important chemical reaction that may greatlymore » impact the bioavailability and mobility of hexavalent chromium in the subsurface is chemical binding to the surfaces of particulates, termed adsorption or surface complexation. Quantitative thermodynamic surface complexation models have been derived that can correctly calculate hexavalent chromium adsorption on well-characterized materials over ranges in subsurface conditions, such pH and salinity. However, models have not yet been developed for hexavalent chromium adsorption on many important constituents of natural soils and sediments, such as clay minerals. Furthermore, most of the existing thermodynamic models have been developed for relatively simple, single solid systems and have rarely been tested for the complex mixtures of solids present in real sediments and soils. In this study, the adsorption of hexavalent chromium was measured as a function of pH (3-10), salinity (0.001 to 0.1 M NaNO3), and partial pressure of carbon dioxide(0-5%) on a suite of naturally-occurring solids including goethite (FeOOH), hydrous manganese oxide (MnOOH), hydrous ferric oxide (Fe(OH)3), γ-alumina (Al2O3), kaolinite (Al2Si2O5(OH)4), and montmorillonite (Na3(Al, Mg)2Si4O10(OH)2-nH2O). The results show that all of these materials can bind substantial quantities of hexavalent chromium, especially at low pH. Unexpectedly, experiments with the clay minerals kaolinite and montmorillonite suggest that hexavalent chromium may interact with these solids over much longer periods of time than expected. Furthermore, hexavalent chromium may irreversibly bind to these solids, perhaps because of oxidation-reduction reactions occurring on the surfaces of the clay minerals. More work should be done to investigate and quantify these chemical reactions. Experiments conducted with mixtures of goethite, hydrous manganese oxide, hydrous ferric oxide, γ-alumina, montmorillonite and kaolinite demonstrate that it is possible to correctly predict hexavalent chromium binding in the presence of multiple minerals using thermodynamic models derived for the simpler systems. Further, these models suggest that of the six solid considered in this study, goethite is typically the solid to which most of the hexavalent chromium will bind. Experiments completed with organic-rich and organic-poor natural sediments demonstrate that in organic-rich substrates, organic matter is likely to control uptake of the hexavalent chromium. The models derived and tested in this study for hexavalent chromium binding to γ-alumina, hydrous manganese oxide, goethite, hydrous ferric oxide and clay minerals can be used to better predict changes in hexavalent chromium bioavailability and mobility in contaminated sediments and soils.« less

Survey of Portions of the Chromium-Cobalt-Nickel-Molybdenum Quaternary System at 1,200 Degrees C

NASA Technical Reports Server (NTRS)

Rideout, Sheldon Paul; Beck, Paul A

1953-01-01

A survey was made of portions of the chromium-cobalt-nickel-molybdenum quaternary system at 1,200 degrees c by means of microscopic and x-ray diffraction studies. Since the face-centered cubic (alpha) solid solutions form the matrix of almost all practically useful high-temperature alloys, the solid solubility limits of the quaternary alpha phase were determined up to 20 percent molybdenum. The component cobalt-nickel-molybdenum, chromium-cobalt-molybdenum, and chromium-nickel-molybdenum ternary systems were also studied. The survey of these systems was confined to the determination of the boundaries of the face-centered cubic (alpha) solid solutions and of the phases coexisting with alpha at 1,200 degrees c.

Stability of chromium (III) sulfate in atmospheres containing oxygen and sulfur

NASA Technical Reports Server (NTRS)

Jacob, K. T.; Rao, B. D.; Nelson, H. G.

1978-01-01

The stability of chromium sulfate in the temperature range from 880 K to 1040 K was determined by employing a dynamic gas-solid equilibration technique. The solid chromium sulfate was equilibrated in a gas stream of controlled SO3 potential. Thermogravimetric and differential thermal analyses were used to follow the decomposition of chromium sulfate. X-ray diffraction analysis indicated that the decomposition product was crystalline Cr2O3 and that the mutual solubility between Cr2(SO4)3 and Cr2O3 was negligible. Over the temperature range investigated, the decomposition pressure were significantly high so that chromium sulfate is not expected to form on commercial alloys containing chromium when exposed to gaseous environments containing oxygen and sulfur (such as those encountered in coal gasification).

Auxiliary Electrodes for Chromium Vapor Sensors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fergus, Jeffrey; Shahzad, Moaiz; Britt, Tommy

Measurement of chromia-containing vapors in solid oxide fuel cell systems is useful for monitoring and addressing cell degradation caused by oxidation of the chomia scale formed on alloys for interconnects and balance-of-plant components. One approach to measuring chromium is to use a solid electrolyte with an auxiliary electrode that relates the partial pressure of the chromium containing species to the mobile species in the electrolyte. One example is YCrO3 which can equilibrate with the chromium containing vapor and yttrium in yttria stabilized zirconia to establish an oxygen activity. Another is Na2CrO4 which can equilibrate with the chromium-containing vapor to establishmore » a sodium activity.« less

FERRATE TREATMENT FOR REMOVING CHROMIUM FROM HIGH-LEVEL RADIOACTIVE TANK WASTE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sylvester, Paul; Rutherford, Andy; Gonzalez-Martin, Anuncia

2000-12-01

A method has been developed for removing chromium from alkaline high-level radioactive tank waste. Removing chromium from these wastes is critical in reducing the volume of waste requiring expensive immobilization and deep geologic disposition. The method developed is based on the oxidation of insoluble chromium(III) compounds to soluble chromate using ferrate. The tests conducted with a simulated Hanford tank sludge indicate that the chromium removal with ferrate is more efficient at 5 M NaOH than at 3 M NaOH. Chromium removal increases with increasing Fe(VI)/Cr(III) molar ratio, but the chromium removal tends to level out for Fe(VI)/Cr(III) greater than 10.more » Increasing temperature leads to better chromium removal, but higher temperatures also led to more rapid ferrate decomposition. Tests with radioactive Hanford tank waste generally confirmed the simulant results. In all cases examined, ferrate enhanced the chromium removal, with a typical removal of around 60-70% of the total chromium present in the washed sludge solids. The ferrate leachate solutions did not contain significant concentrations of transuranic elements, so these solutions could be handled as low-activity waste.« less

Experimental evaluation of chromium-carbide-based solid lubricant coatings for use to 760 C

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher

1987-01-01

A research program is described which further developed and investigated chromium carbide based self-lubricating coatings for use to 760 C. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The three coating components were blended in powder form, applied to stainless steel substrates by plasma spraying and then diamond ground to the desired coating thickness. A variety of coating compositions was tested to determine the coating composition which gave optimum tribological results. Coatings were tested in air, helium, and hydrogen at temperatures from 25 to 760 C. Several counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications, such as piston ring/cylinder liner couples for Stirling engines. In general, silver and fluoride additions to chromium carbide reduced the friction coefficient and increased the wear resistance relative to the unmodified coating. The lubricant additives acted synergistically in reducing friction and wear.

Calculation of open and closed system elastic coefficients for multicomponent solids

NASA Astrophysics Data System (ADS)

Mishin, Y.

2015-06-01

Thermodynamic equilibrium in multicomponent solids subject to mechanical stresses is a complex nonlinear problem whose exact solution requires extensive computations. A few decades ago, Larché and Cahn proposed a linearized solution of the mechanochemical equilibrium problem by introducing the concept of open system elastic coefficients [Acta Metall. 21, 1051 (1973), 10.1016/0001-6160(73)90021-7]. Using the Ni-Al solid solution as a model system, we demonstrate that open system elastic coefficients can be readily computed by semigrand canonical Monte Carlo simulations in conjunction with the shape fluctuation approach. Such coefficients can be derived from a single simulation run, together with other thermodynamic properties needed for prediction of compositional fields in solid solutions containing defects. The proposed calculation approach enables streamlined solutions of mechanochemical equilibrium problems in complex alloys. Second order corrections to the linear theory are extended to multicomponent systems.

Finite-deformation phase-field chemomechanics for multiphase, multicomponent solids

NASA Astrophysics Data System (ADS)

Svendsen, Bob; Shanthraj, Pratheek; Raabe, Dierk

2018-03-01

The purpose of this work is the development of a framework for the formulation of geometrically non-linear inelastic chemomechanical models for a mixture of multiple chemical components diffusing among multiple transforming solid phases. The focus here is on general model formulation. No specific model or application is pursued in this work. To this end, basic balance and constitutive relations from non-equilibrium thermodynamics and continuum mixture theory are combined with a phase-field-based description of multicomponent solid phases and their interfaces. Solid phase modeling is based in particular on a chemomechanical free energy and stress relaxation via the evolution of phase-specific concentration fields, order-parameter fields (e.g., related to chemical ordering, structural ordering, or defects), and local internal variables. At the mixture level, differences or contrasts in phase composition and phase local deformation in phase interface regions are treated as mixture internal variables. In this context, various phase interface models are considered. In the equilibrium limit, phase contrasts in composition and local deformation in the phase interface region are determined via bulk energy minimization. On the chemical side, the equilibrium limit of the current model formulation reduces to a multicomponent, multiphase, generalization of existing two-phase binary alloy interface equilibrium conditions (e.g., KKS). On the mechanical side, the equilibrium limit of one interface model considered represents a multiphase generalization of Reuss-Sachs conditions from mechanical homogenization theory. Analogously, other interface models considered represent generalizations of interface equilibrium conditions consistent with laminate and sharp-interface theory. In the last part of the work, selected existing models are formulated within the current framework as special cases and discussed in detail.

Hot-tearing of multicomponent Al-Cu alloys based on casting load measurements in a constrained permanent mold

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sabau, Adrian S; Mirmiran, Seyed; Glaspie, Christopher

Hot-tearing is a major casting defect that is often difficult to characterize, especially for multicomponent Al alloys used for cylinder head castings. The susceptibility of multicomponent Al-Cu alloys to hot-tearing during permanent mold casting was investigated using a constrained permanent mold in which the load and displacement was measured. The experimental results for hot tearing susceptibility are compared with those obtained from a hot-tearing criterion based temperature range evaluated at fraction solids of 0.87 and 0.94. The Cu composition was varied from approximately 5 to 8 pct. (weight). Casting experiments were conducted without grain refining. The measured load during castingmore » can be used to indicate the severity of hot tearing. However, when small hot-tears are present, the load variation cannot be used to detect and assess hot-tearing susceptibility.« less

Chemical ageing and transformation of diffusivity in semi-solid multi-component organic aerosol particles

NASA Astrophysics Data System (ADS)

Pfrang, C.; Shiraiwa, M.; Pöschl, U.

2011-04-01

Recent experimental evidence underlines the importance of reduced diffusivity in amorphous semi-solid or glassy atmospheric aerosols. This paper investigates the impact of diffusivity on the ageing of multi-component reactive organic particles representative of atmospheric cooking aerosols. We apply and extend the recently developed KM-SUB model in a study of a 12-component mixture containing oleic and palmitoleic acids. We demonstrate that changes in the diffusivity may explain the evolution of chemical loss rates in ageing semi-solid particles, and we resolve surface and bulk processes under transient reaction conditions considering diffusivities altered by oligomerisation. This new model treatment allows prediction of the ageing of mixed organic multi-component aerosols over atmospherically relevant time scales and conditions. We illustrate the impact of changing diffusivity on the chemical half-life of reactive components in semi-solid particles, and we demonstrate how solidification and crust formation at the particle surface can affect the chemical transformation of organic aerosols.

Chemical ageing and transformation of diffusivity in semi-solid multi-component organic aerosol particles

NASA Astrophysics Data System (ADS)

Pfrang, C.; Shiraiwa, M.; Pöschl, U.

2011-07-01

Recent experimental evidence underlines the importance of reduced diffusivity in amorphous semi-solid or glassy atmospheric aerosols. This paper investigates the impact of diffusivity on the ageing of multi-component reactive organic particles approximating atmospheric cooking aerosols. We apply and extend the recently developed KM-SUB model in a study of a 12-component mixture containing oleic and palmitoleic acids. We demonstrate that changes in the diffusivity may explain the evolution of chemical loss rates in ageing semi-solid particles, and we resolve surface and bulk processes under transient reaction conditions considering diffusivities altered by oligomerisation. This new model treatment allows prediction of the ageing of mixed organic multi-component aerosols over atmospherically relevant timescales and conditions. We illustrate the impact of changing diffusivity on the chemical half-life of reactive components in semi-solid particles, and we demonstrate how solidification and crust formation at the particle surface can affect the chemical transformation of organic aerosols.

The Solidification of Multicomponent Alloys

PubMed Central

Boettinger, William J.

2017-01-01

Various topics taken from the author’s research portfolio that involve multicomponent alloy solidification are reviewed. Topics include: ternary eutectic solidification and Scheil-Gulliver paths in ternary systems. A case study of the solidification of commercial 2219 aluminum alloy is described. Also described are modifications of the Scheil-Gulliver analysis to treat dendrite tip kinetics and solid diffusion for multicomponent alloys. PMID:28819348

Chromium speciation in environmental samples using a solid phase spectrophotometric method

NASA Astrophysics Data System (ADS)

Amin, Alaa S.; Kassem, Mohammed A.

2012-10-01

A solid phase extraction technique is proposed for preconcentration and speciation of chromium in natural waters using spectrophotometric analysis. The procedure is based on sorption of chromium(III) as 4-(2-benzothiazolylazo)2,2'-biphenyldiol complex on dextran-type anion-exchange gel (Sephadex DEAE A-25). After reduction of Cr(VI) by 0.5 ml of 96% concentrated H2SO4 and ethanol, the system was applied to the total chromium. The concentration of Cr(VI) was calculated as the difference between the total Cr and the Cr(III) content. The influences of some analytical parameters such as: pH of the aqueous solution, amounts of 4-(2-benzothiazolylazo)2,2'-biphenyldiol (BTABD), and sample volumes were investigated. The absorbance of the gel, at 628 and 750 nm, packed in a 1.0 mm cell, is measured directly. The molar absorptivities were found to be 2.11 × 107 and 3.90 × 107 L mol-1 cm-1 for 500 and 1000 ml, respectively. Calibration is linear over the range 0.05-1.45 μg L-1 with RSD of <1.85% (n = 8.0). Using 35 mg exchanger, the detection and quantification limits were 13 and 44 ng L-1 for 500 ml sample, whereas for 1000 ml sample were 8.0 and 27 ng L-1, respectively. Increasing the sample volume can enhance the sensitivity. No considerable interferences have been observed from other investigated anions and cations on the chromium speciation. The proposed method was applied to the speciation of chromium in natural waters and total chromium preconcentration in microwave digested tobacco, coffee, tea, and soil samples. The results were simultaneously compared with those obtained using an ET AAS method, whereby the validity of the method has been tested.

Adsorption and mobility of metals in build-up on road surfaces.

PubMed

Gunawardana, Chandima; Egodawatta, Prasanna; Goonetilleke, Ashantha

2015-01-01

The study investigated the adsorption and bioavailability characteristics of traffic generated metals common to urban land uses, in road deposited solids particles. To validate the outcomes derived from the analysis of field samples, adsorption and desorption experiments were undertaken. The analysis of field samples revealed that metals are selectively adsorbed to different charge sites on solids. Zinc, copper, lead and nickel are adsorbed preferentially to oxides of manganese, iron and aluminium. Lead is adsorbed to organic matter through chemisorption. Cadmium and chromium form weak bonding through cation exchange with most of the particle sizes. Adsorption and desorption experiments revealed that at high metal concentrations, chromium, copper and lead form relatively strong bonds with solids particles while zinc is adsorbed through cation exchange with high likelihood of being released back into solution. Outcomes from this study provide specific guidance for the removal of metals from stormwater based on solids removal. Copyright © 2014 Elsevier Ltd. All rights reserved.

Stratiform chromite deposit model: Chapter E in Mineral deposit models for resource assessment

USGS Publications Warehouse

Schulte, Ruth F.; Taylor, Ryan D.; Piatak, Nadine M.; Seal, Robert R.

2012-01-01

Most environmental concerns associated with the mining and processing of chromite ore focus on the solubility of chromium and its oxidation state. Although trivalent chromium (Cr3+) is an essential micronutrient for humans, hexavalent chromium (Cr6+) is highly toxic. Chromium-bearing solid phases that occur in the chromite ore-processing residue, for example, can effect the geochemical behavior and oxidation state of chromium in the environment.

Mathematical Modeling and Optimization Studies on Development of Fuel Cells for Multifarious Applications

DTIC Science & Technology

2010-05-12

multicomponent steady-state model for liquid -feed solid polymer electrolyte DBFCs. These fuel cells use sodium borohydride (NaBH4) in alkaline media...layers, diffusion layers and the polymer electrolyte membrane for a liquid feed DBFC. Diffusion of reactants within and between the pores is accounted...projected for futuristic portable applications. In this project we developed a three- dimensional, multicomponent steady-state model for liquid -feed solid

Predicting the tensile strength of compacted multi-component mixtures of pharmaceutical powders.

PubMed

Wu, Chuan-Yu; Best, Serena M; Bentham, A Craig; Hancock, Bruno C; Bonfield, William

2006-08-01

Pharmaceutical tablets are generally produced by compacting a mixture of several ingredients, including active drugs and excipients. It is of practical importance if the properties of such tablets can be predicted on the basis of the ones for constituent components. The purpose of this work is to develop a theoretical model which can predict the tensile strength of compacted multi-component pharmaceutical mixtures. The model was derived on the basis of the Ryshkewitch-Duckworth equation that was originally proposed for porous materials. The required input parameters for the model are the relative density or solid fraction (ratio of the volume of solid materials to the total volume of the tablets) of the multi-component tablets and parameters associated with the constituent single-component powders, which are readily accessible. The tensile strength of tablets made of various powder blends at different relative density was also measured using diametrical compression. It has been shown that the tensile strength of the multi-component powder compacts is primarily a function of the solid fraction. Excellent agreement between prediction and experimental data for tablets of binary, ternary and four-component blends of some widely used pharmaceutical excipients was obtained. It has been demonstrated that the proposed model can well predict the tensile strength of multi-component pharmaceutical tablets. Thus, the model will be a useful design tool for formulation engineers in the pharmaceutical industry.

Reconceptualizing Working Memory in Educational Research

ERIC Educational Resources Information Center

Fenesi, Barbara; Sana, Faria; Kim, Joseph A.; Shore, David I.

2015-01-01

In recent years, research from cognitive science has provided a solid theoretical framework to develop evidence-based interventions in education. In particular, research into reading, writing, language, mathematics and multimedia learning has been guided by the application of Baddeley's multicomponent model of working memory. However, an…

TREATMENT OF HEXAVALENT CHROMIUM IN CHROMITE ORE PROCESSING SOLID WASTE USING A MIXED REDUCTANT SOLUTION OF FERROUS SULFATE AND SODIUM DITHIONITE

EPA Science Inventory

We developed a method for disseminating ferrous iron in the subsurface to enhance chemical reduction of hexavalent chromium (Cr(VI)) in a chromite ore processing solid waste derived from the production of ferrochrome alloy. The method utilizes ferrous sulfate (FeSO4) in combinati...

Analysis and Thermodynamic Prediction of Hydrogen Solution in Solid and Liquid Multicomponent Aluminum Alloys

NASA Astrophysics Data System (ADS)

Anyalebechi, P. N.

Reported experimentally determined values of hydrogen solubility in liquid and solid Al-H and Al-H-X (where X = Cu, Si, Zn, Mg, Li, Fe or Ti) systems have been critically reviewed and analyzed in terms of Wagner's interaction parameter. An attempt has been made to use Wagner's interaction parameter and statistic linear regression models derived from reported hydrogen solubility limits for binary aluminum alloys to predict the hydrogen solubility limits in liquid and solid (commercial) multicomponent aluminum alloys. Reasons for the observed poor agreement between the predicted and experimentally determined hydrogen solubility limits are discussed.

The Structure and Properties of Plasma Sprayed Iron Oxide Doped Manganese Cobalt Oxide Spinel Coatings for SOFC Metallic Interconnectors

NASA Astrophysics Data System (ADS)

Puranen, Jouni; Lagerbom, Juha; Hyvärinen, Leo; Kylmälahti, Mikko; Himanen, Olli; Pihlatie, Mikko; Kiviaho, Jari; Vuoristo, Petri

2011-01-01

Manganese cobalt oxide spinel doped with Fe2O3 was studied as a protective coating on ferritic stainless steel interconnects. Chromium alloying causes problems at high operation temperatures in such oxidizing conditions where chromium compounds evaporate and poison the cathode active area, causing the degradation of the solid oxide fuel cell. In order to prevent chromium evaporation, these interconnectors need a protective coating to block the chromium evaporation and to maintain an adequate electrical conductivity. Thermal spraying is regarded as a promising way to produce dense and protective layers. In the present work, the ceramic Mn-Co-Fe oxide spinel coatings were produced by using the atmospheric plasma spray process. Coatings with low thickness and low amount of porosity were produced by optimizing deposition conditions. The original spinel structure decomposed because of the fast transformation of solid-liquid-solid states but was partially restored by using post-annealing treatment.

Acceptable aluminum additions for minimal environmental effect in iron-aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sikka, V.K.; Viswanathan, S.; Vyas, S.

A systematic study of iron-aluminum alloys has shown that Fe-16 at. % Al alloys are not very sensitive to environmental embrittlement. The Fe-22 and -28 at. % Al alloys are sensitive to environmental embrittlement, and the effect can be reduced by the addition of chromium and through the control of grain size by additions of zirconium and carbon. The Fe-16 at. % Al binary, and alloys based on it, yielded over 20% room-temperature (RT) elongation even after high-temperature annealing treatments at 1100[degree]C. The best values for the Fe-22 and -28 at. % Al-base alloys after similar annealing treatments were 5more » and 10%, respectively. A multicomponent alloy, FAP, based on Fe- 16 at. % Al was designed, which gave an RT ductility of over 25%.« less

Acceptable aluminum additions for minimal environmental effect in iron-aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sikka, V.K.; Viswanathan, S.; Vyas, S.

A systematic study of iron-aluminum alloys has shown that Fe-16 at. % Al alloys are not very sensitive to environmental embrittlement. The Fe-22 and -28 at. % Al alloys are sensitive to environmental embrittlement, and the effect can be reduced by the addition of chromium and through the control of grain size by additions of zirconium and carbon. The Fe-16 at. % Al binary, and alloys based on it, yielded over 20% room-temperature (RT) elongation even after high-temperature annealing treatments at 1100{degree}C. The best values for the Fe-22 and -28 at. % Al-base alloys after similar annealing treatments were 5more » and 10%, respectively. A multicomponent alloy, FAP, based on Fe- 16 at. % Al was designed, which gave an RT ductility of over 25%.« less

Multicomponent Transport through Realistic Zeolite Membranes: Characterization & Transport in Nanoporous Networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

William C. Conner

These research studies focused on the characterization and transport for porous solids which comprise both microporosity and mesoporosity. Such materials represent membranes made from zeolites as well as for many new nanoporous solids. Several analytical sorption techniques were developed and evaluated by which these multi-dimensional porous solids could be quantitatively characterized. Notably an approach by which intact membranes could be studied was developed and applied to plate-like and tubular supported zeolitic membranes. Transport processes were studied experimentally and theoretically based on the characterization studies.

Activated microporous materials through polymerization of microemulsion precursors

NASA Astrophysics Data System (ADS)

Venkatesan, Arunkumar

Microemulsions have been well studied for their unique characteristics. They are isotropic, thermodynamically stable and microstructured mixtures of oil and water stabilized by one or more surfactant species. They are formed spontaneously and are thermodynamically stable. Microemulsion precursors can be polymerized to make microporous solids with controlled pore structure and sizes. These polymeric solids have been studied extensively in the past. Although the fundamental properties of the microporous solids have been studied in depth, the development of specific applications that will utilize the unique properties of these solids has not been exhaustively researched. The current work establishes the feasibility of making activated microporous solids from microemulsion precursors, by the use of a ligand that chelates metals and also attaches itself to the polymer monolith. It also uses a novel 'in-situ' incorporation by combining the formulation and incorporation steps into one. The research objectives are, to formulate a microemulsion system that can yield useful microporous solids upon polymerization and activation, to characterize these solids using existing techniques available for analysis of similar microporous solids, to identify and understand the effect of the variables in the system and to study the influence of these variables on the performance characteristics of this material. Characterization techniques like Differential Scanning Calorimetry, Thermogravimetric Analysis and Scanning Electron Microscopy were used. A hydroxyethylmethylmethacrylate/methylmethacrylate/aqueous phase containing 10% SDS' system was chosen as the precursor microemulsion and the corresponding microporous solids were made. A metal chelating ligand, Congo Red, was incorporated onto the microporous polymer using NaOH as a binding agent. The ability of the resultant 'activated' microporous solid to remove metal ions from solution, was evaluated. The metal ion chosen was chromium and the influence of variables such as NaOH loading, Congo Red loading, Cross linker content etc. were studied. It was found that the microporous solids were effective in removing chromium from solution. They outperformed similar polymeric solids with ligands (reported in literature) in chromium removal. A removal of about 1500 micro moles of chromium ions per gram of dry polymer from a solution of 5 mMol/L initial concentration of chromium was observed. This is much more than the removal of 340 micro moles/gram of dry polymer reported in literature for comparable non-microporous systems.

INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Method for calculation of electrical and optical properties of laser active media

NASA Astrophysics Data System (ADS)

Aleksandrov, D. G.; Filipov, F. I.

1988-11-01

A method is proposed for calculation of the electron band structure of multicomponent semiconductor solid solutions. Use is made of virtual atomic orbitals formed from real orbitals. The method represents essentially an approximation of a multicomponent solid solution by a binary one. The matrix elements of the Hamiltonian are obtained in the methods of linear combinations of atomic and bound orbitals. Some approximations used in these methods are described.

MODELING MULTICOMPONENT ORGANIC CHEMICAL TRANSPORT IN THREE-FLUID-PHASE POROUS MEDIA

EPA Science Inventory

A two dimensional finite-element model was developed to predict coupled transient flow and multicomponent transport of organic chemicals which can partition between NAPL, water, gas and solid phases in porous media under the assumption of local chemical equilibrium. as-phase pres...

MODELING MULTICOMPONENT ORGANIC CHEMICAL TRANSPORT IN THREE FLUID PHASE POROUS MEDIA

EPA Science Inventory

A two-dimensional finite-element model was developed to predict coupled transient flow and multicomponent transport of organic chemicals which can partition between nonaqueous phase liquid, water, gas and solid phases in porous media under the assumption of local chemical equilib...

Chromium speciation in environmental samples using a solid phase spectrophotometric method.

PubMed

Amin, Alaa S; Kassem, Mohammed A

2012-10-01

A solid phase extraction technique is proposed for preconcentration and speciation of chromium in natural waters using spectrophotometric analysis. The procedure is based on sorption of chromium(III) as 4-(2-benzothiazolylazo)2,2'-biphenyldiol complex on dextran-type anion-exchange gel (Sephadex DEAE A-25). After reduction of Cr(VI) by 0.5 ml of 96% concentrated H(2)SO(4) and ethanol, the system was applied to the total chromium. The concentration of Cr(VI) was calculated as the difference between the total Cr and the Cr(III) content. The influences of some analytical parameters such as: pH of the aqueous solution, amounts of 4-(2-benzothiazolylazo)2,2'-biphenyldiol (BTABD), and sample volumes were investigated. The absorbance of the gel, at 628 and 750 nm, packed in a 1.0 mm cell, is measured directly. The molar absorptivities were found to be 2.11×10(7) and 3.90×10(7) L mol(-1)cm(-1) for 500 and 1000 ml, respectively. Calibration is linear over the range 0.05-1.45 μg L(-1) with RSD of <1.85% (n=8.0). Using 35 mg exchanger, the detection and quantification limits were 13 and 44 ng L(-1) for 500 ml sample, whereas for 1000 ml sample were 8.0 and 27 ng L(-1), respectively. Increasing the sample volume can enhance the sensitivity. No considerable interferences have been observed from other investigated anions and cations on the chromium speciation. The proposed method was applied to the speciation of chromium in natural waters and total chromium preconcentration in microwave digested tobacco, coffee, tea, and soil samples. The results were simultaneously compared with those obtained using an ET AAS method, whereby the validity of the method has been tested. Copyright © 2012 Elsevier B.V. All rights reserved.

Method for fabricating cermets of alumina-chromium systems

DOEpatents

Morgan, Chester S.

1983-01-01

Cermet insulators resistant to thermal and mechanical shock are prepared from alumina-chromium systems by providing an Al.sub.2 O.sub.3 material of about 0.5 to 7.0 micron size with a solid-hydrocarbon overcoating by slurring an effective amount of said solid hydrocarbon in a solvent mixture containing said Al.sub.2 O.sub.3 and thereafter evaporating said solvent, contacting said coated Al.sub.2 O.sub.3 with a solution of chromium precursor compound, heating the resulting mixture in a reducing environment to a temperature above the decomposition temperature of said chromium precursor compound but less than the melting temperature of the Al.sub.2 O.sub.3 or chromium for sufficient duration to yield a particulate compound having chromium essentially dispersed throughout the Al.sub.2 O.sub.3, and then densifying said particulate to provide said cermet characterized by a theoretical density in excess of 96% and having 0.1 to 10.0 vol.% elemental chromium metal present therein as a dispersed phase at the boundaries of the Al.sub.2 O.sub.3 material. Cermet components prepared thereby are useful in high temperature equipment, advanced heat engines, and nuclear-related equipment applications where electrical or thermal insulators are required.

Method for fabricating cermets of alumina-chromium systems. [Patent application

DOEpatents

Morgan, C.S.

1981-10-05

Cermet insulators resistant to thermal and mechanical shock are prepared from alumina-chromium systems in the following way: by providing an Al/sub 2/O/sub 3/ material of about 0.5 to 7.0 micron size with a solid-hydrocarbon overcoating by slurrying an effective amount of said solid hydrocarbon in a solvent mixture containing said Al/sub 2/O/sub 3/ and thereafter evaporating said solvent, contacting said coated Al/sub 2/O/sub 3/ with a solution of chromium precursor compound, heating the resulting mixture in a reducing environment to a temperature above the decomposition temperature of said chromium precursor compound but less than the melting temperature of the Al/sub 2/O/sub 3/ or chromium for sufficient duration to yield a particulate compound having chromium essentially dispersed throughout the Al/sub 2/O/sub 3/, and then densifying said particulate to provide said cermet characterized by a theoretical density in excess of 96% and having 0.1 to 10.0 vol. % elemental chromium metal present therein as a dispersed phase at the boundaries of the Al/sub 2/O/sub 3/ material. Cermet components prepared thereby are useful in high temperature equipment, advanced heat engines, and nuclear-related equipment applications where electrical or thermal insulators are required.

CrIII as an alternative to RuII in metallo-supramolecular chemistry.

PubMed

Zare, Davood; Doistau, Benjamin; Nozary, Homayoun; Besnard, Céline; Guénée, Laure; Suffren, Yan; Pelé, Anne-Laure; Hauser, Andreas; Piguet, Claude

2017-07-18

Compared to divalent ruthenium coordination complexes, which are widely exploited as parts of multi-component photonic devices, optically active trivalent chromium complexes are under-represented in multi-metallic supramolecular architectures performing energy conversion mainly because of the tricky preparation of stable heteroleptic Cr III building blocks. We herein propose some improvements with the synthesis of a novel family of kinetically inert heteroleptic bis-terdentate mononuclear complexes, which can be incorporated into dinuclear rod-like dyads as a proof-of-concept. The mechanism and magnitude of intermetallic CrCr communication have been unraveled by a combination of magnetic, photophysical and thermodynamic investigations. Alternated aromatic/alkyne connectors provided by Sonogashira coupling reactions emerge as the most efficient wires for long-distance communication between two chromium centres bridged by Janus-type back-to-back bis-terdentate receptors.

X-ray diffraction, FTIR, UV-VIS and SEM studies on chromium (III) complexes

NASA Astrophysics Data System (ADS)

Mishra, Ashutosh; Dwivedi, Jagrati; Shukla, Kritika

2015-06-01

Five Chromium (III) complexes have been prepared using Schiff base ligands which derived from benzoin and five different amino acids (H2N-R). Samples were characterized by XRD, FTIR, UV-VIS and SEM method. X-Ray diffraction pattern analyzed that all chromium (III) complexes have hexagonal structure and crystalline, in nature, using Bruker D8 Advance instrument. Using VERTAX 70, FTIR spectroscopy reveals that Samples have (C=N), (C-O), (M-N) and (M-O) bonds in the range of 4000-400cm-1. UV-VIS spectroscopy give information that samples absorb the visible light which is in the range of 380-780nm. For this, Lambda 960 spectrometer used. SEM is designed for studying of the solid objects, using JEOL JSM 5600 instrument.

Core-shell chromium silicide-silicon nanopillars: a contact material for future nanosystems.

PubMed

Chang, Mu-Tung; Chen, Chih-Yen; Chou, Li-Jen; Chen, Lih-Juann

2009-11-24

Chromium silicide nanostructures are fabricated inside silicon nanopillars grown by the vapor-liquid-solid mechanism. The remarkable field-emission behavior of these nanostructures results from extensive improvement of carrier transport due to the reduced energy barrier between the metal and semiconductor layers. The results warrant consideration of chromium silicide as a potentially important contact material in future nanosystems.

Radiationless Transitions and Excited-State Absorption of Low-Field Chromium Complexes in Solids

DTIC Science & Technology

1989-07-20

host-lattice modes and, in the case of the scandium compound with 5 % chromium concentration, of the a and tIg 2g localized modes. The local-mode...Radiationless transitions and excited-state Final report I/I/86-5/31/89 absorption of low-field chromium complexes 6. PERFORMING ORG. REPORT NUMBER ( 1 in...complexes, chromium ; tunable lasers, high pressure,-photoluminescence 4. 26, AMTVrAC? (Cbm e @CAP N Igemem’ a IdoMit’ by block nambew) The continuation of a

Competition between Bose-Einstein Condensation and Spin Dynamics.

PubMed

Naylor, B; Brewczyk, M; Gajda, M; Gorceix, O; Maréchal, E; Vernac, L; Laburthe-Tolra, B

2016-10-28

We study the impact of spin-exchange collisions on the dynamics of Bose-Einstein condensation by rapidly cooling a chromium multicomponent Bose gas. Despite relatively strong spin-dependent interactions, the critical temperature for Bose-Einstein condensation is reached before the spin degrees of freedom fully thermalize. The increase in density due to Bose-Einstein condensation then triggers spin dynamics, hampering the formation of condensates in spin-excited states. Small metastable spinor condensates are, nevertheless, produced, and they manifest in strong spin fluctuations.

New ceramics incorporated with industrial by-products as pore formers for sorption of toxic chromium from aqueous media

NASA Astrophysics Data System (ADS)

Domopoulou, Artemi

2015-04-01

The incorporation of secondary resources including various industrial wastes as pore-forming agents into clayey raw material mixtures for the development of tailored porous ceramic microstructures is currently of increasing interest. In the present research, sintered ceramic compacts were developed incorporated with industrial solid by-products as pore formers, and then used as new sorbents for chromium removal from aqueous media. The microstructures obtained were characterized through X-ray diffraction (XRD) analysis as well as scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). Sorption potential of chromium from synthetic solutions on the porous ceramics was studied by static adsorption experiments as a function of the pore-former percentage in the ceramic matrix as well as the initial heavy metal (chromium) concentration, solution pH and temperature. Kinetic studies were conducted and adsorption isotherms of chromium were determined using the Langmuir equation. Preliminary experimental results concerning the adsorption characteristics of chromium on the ceramic materials produced appear encouraging for their possible beneficial use as new sorbents for the removal of toxic chromium from aqueous media. Keywords: sorbents, ceramics, industrial solid by-products, pore-former, chromium. Acknowledgements: This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program ARCHIMEDES III: Investing in knowledge society through the European Social Fund.

New ceramics incorporated with industrial by-products as pore formers for sorption of toxic chromium from aqueous media

NASA Astrophysics Data System (ADS)

Domopoulou, Asimina; Spiliotis, Xenofon; Baklavaridis, Apostolos; Papapolymerou, George; Karayannis, Vayos

2015-04-01

The incorporation of secondary resources including various industrial wastes as pore-forming agents into clayey raw material mixtures for the development of tailored porous ceramic microstructures is currently of increasing interest. In the present research, sintered ceramic compacts were developed incorporated with industrial solid by-products as pore formers, and then used as new sorbents for chromium removal from aqueous media. The microstructures obtained were characterized through X-ray diffraction (XRD) analysis as well as scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). Sorption potential of chromium from synthetic solutions on the porous ceramics was studied by static adsorption experiments as a function of the pore-former percentage in the ceramic matrix as well as the initial heavy metal (chromium) concentration, solution pH and temperature. Kinetic studies were conducted and adsorption isotherms of chromium were determined using the Langmuir equation. Preliminary experimental results concerning the adsorption characteristics of chromium on the ceramic materials produced appear encouraging for their possible beneficial use as new sorbents for the removal of toxic chromium from aqueous media. Keywords: sorbents, ceramics, industrial solid by-products, pore former, chromium. Acknowledgements: This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program ARCHIMEDES III: Investing in knowledge society through the European Social Fund.

Life Cycle Assessment for PC Blend 2 Aircraft Radome Depainter

DTIC Science & Technology

1996-09-01

Trivalent chromium compounds are considerably less toxic than hexavalent forms and are neither irritating nor corrosive. 25. IRON (W) Ecosystem: Visibility...acquisition and combustion is a source of waterborne acid, ammonia, BOD, chromium , COD, dissolved solids, iron, lead, metal ion, oil, phenol...intermediates for DBE. Chromium , phenol, zinc, and COD process emissions come from petroleum refinery operations. The production of ammonia also produces

Avoiding chromium transport from stainless steel interconnects into contact layers and oxygen electrodes in intermediate temperature solid oxide electrolysis stacks

NASA Astrophysics Data System (ADS)

Schlupp, Meike V. F.; Kim, Ji Woo; Brevet, Aude; Rado, Cyril; Couturier, Karine; Vogt, Ulrich F.; Lefebvre-Joud, Florence; Züttel, Andreas

2014-12-01

We investigated the ability of (La0.8Sr0.2)(Mn0.5Co0.5)O3-δ (LSMC) and La(Ni0.6Fe0.4)O3-δ (LNF) contact coatings to avoid the transport of Cr from steel interconnects to solid oxide electrolysis electrodes, especially to the anode. The transport of chromium from commercial Crofer 22 APU (ThyssenKrupp) and K41X (AISI441, Aperam Isbergues) steels through LSMC and LNF contact coatings into adjacent (La0.8Sr0.2)MnO3-δ (LSM) oxygen electrodes was investigated in an oxygen atmosphere at 700 °C. Chromium concentrations of up to 4 atom% were detected in the contact coatings after thermal treatments for 3000 h, which also lead to the presence of chromium in adjacent LSM electrodes. Introduction of a dense (Co,Mn)3O4 coating between steel and contact coating was necessary to prevent the diffusion of chromium into contact coatings and electrodes and should lead to extended stack performance and lifetime.

Improvement of chemical composition, structure and mechanical properties of heat-resistant chromium-nickel alloy

NASA Astrophysics Data System (ADS)

Varlamova, S.; Trushnikova, A.; Rumyantsev, B.; Butrim, V.; Simonov, V.

2018-04-01

A thermodynamic analysis of a multicomponent system of the Cr-Ni alloy (Cr-32Ni-1,5W-0,25V-0,5Ti) with small additions of refractory metals was carried out. The microstructure and phase composition of the base alloy (I) and alloy with additional alloying (II) were studied. The effect of additives on the mechanical properties of the Cr-Ni alloy at 20, 900 and 1080 °C was shown. The microstructure of alloys I and II was studied in the fracture zone of samples after tensile tests at different temperatures. We studied the effect of small additives on the microstructure of alloys and changes in the morphology of the structural components (phases) as a function of temperature and degree of deformation.

Study of Chromium Oxide Activities in EAF Slags

NASA Astrophysics Data System (ADS)

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.

Characterization of Pharmaceutical Cocrystals and Salts by Dynamic Nuclear Polarization-Enhanced Solid-State NMR Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Li; Hanrahan, Michael P.; Chakravarty, Paroma

Multicomponent solids such as cocrystals have emerged as a way to control and engineer the stability, solubility and manufacturability of solid active pharmaceutical ingredients (APIs). Cocrystals are typically formed by solution- or solid-phase reactions of APIs with suitable cocrystal coformers, which are often weak acids. One key structural question about a given multicomponent solid is whether it should be classified as a salt, where the basic API is protonated by the acid, or as a cocrystal, where the API and coformer remain neutral and engage in hydrogen bonding interactions. It has previously been demonstrated that solid-state NMR spectroscopy is amore » powerful probe of structure in cocrystals and salts of APIs, however, the poor sensitivity of solid-state NMR spectroscopy usually restricts the types of experiments that can be performed. Here relayed dynamic nuclear polarization (DNP) was applied to reduce solid-state NMR experiments by one to two orders of magnitude for salts and cocrystals of a complex API. The large sensitivity gains from DNP facilitates rapid acquisition of natural isotopic abundance 13C and 15N solid-state NMR spectra. Critically, DNP enables double resonance 1H-15N solid-state NMR experiments such as 2D 1H-15N HETCOR, 1H-15N CP-build up, 15N{1H} J-resolved/attached proton tests, 1H-15N DIPSHIFT and 1H-15N PRESTO. The latter two experiments allow 1H-15N dipolar coupling constants and H-N bond lengths to be accurately measured, providing an unambiguous assignment of nitrogen protonation state and definitive classification of the multi-component solids as cocrystals or salts. In conclusion, these types of measurements should also be extremely useful in the context of polymorph discrimination, NMR crystallography structure determination and for probing hydrogen bonding in a variety of organic materials.« less

Characterization of Pharmaceutical Cocrystals and Salts by Dynamic Nuclear Polarization-Enhanced Solid-State NMR Spectroscopy

DOE PAGES

Zhao, Li; Hanrahan, Michael P.; Chakravarty, Paroma; ...

2018-02-15

Multicomponent solids such as cocrystals have emerged as a way to control and engineer the stability, solubility and manufacturability of solid active pharmaceutical ingredients (APIs). Cocrystals are typically formed by solution- or solid-phase reactions of APIs with suitable cocrystal coformers, which are often weak acids. One key structural question about a given multicomponent solid is whether it should be classified as a salt, where the basic API is protonated by the acid, or as a cocrystal, where the API and coformer remain neutral and engage in hydrogen bonding interactions. It has previously been demonstrated that solid-state NMR spectroscopy is amore » powerful probe of structure in cocrystals and salts of APIs, however, the poor sensitivity of solid-state NMR spectroscopy usually restricts the types of experiments that can be performed. Here relayed dynamic nuclear polarization (DNP) was applied to reduce solid-state NMR experiments by one to two orders of magnitude for salts and cocrystals of a complex API. The large sensitivity gains from DNP facilitates rapid acquisition of natural isotopic abundance 13C and 15N solid-state NMR spectra. Critically, DNP enables double resonance 1H-15N solid-state NMR experiments such as 2D 1H-15N HETCOR, 1H-15N CP-build up, 15N{1H} J-resolved/attached proton tests, 1H-15N DIPSHIFT and 1H-15N PRESTO. The latter two experiments allow 1H-15N dipolar coupling constants and H-N bond lengths to be accurately measured, providing an unambiguous assignment of nitrogen protonation state and definitive classification of the multi-component solids as cocrystals or salts. In conclusion, these types of measurements should also be extremely useful in the context of polymorph discrimination, NMR crystallography structure determination and for probing hydrogen bonding in a variety of organic materials.« less

Pharmaceutical cocrystals, salts and multicomponent systems; intermolecular interactions and property based design.

PubMed

Berry, David J; Steed, Jonathan W

2017-08-01

As small molecule drugs become harder to develop and less cost effective for patient use, efficient strategies for their property improvement become increasingly important to global health initiatives. Improvements in the physical properties of Active Pharmaceutical Ingredients (APIs), without changes in the covalent chemistry, have long been possible through the application of binary component solids. This was first achieved through the use of pharmaceutical salts, within the last 10-15years with cocrystals and more recently coamorphous systems have also been consciously applied to this problem. In order to rationally discover the best multicomponent phase for drug development, intermolecular interactions need to be considered at all stages of the process. This review highlights the current thinking in this area and the state of the art in: pharmaceutical multicomponent phase design, the intermolecular interactions in these phases, the implications of these interactions on the material properties and the pharmacokinetics in a patient. Copyright © 2017 Elsevier B.V. All rights reserved.

Laser Spectroscopy Characterization of Materials for Frequency Agile Solid State Laser Systems

DTIC Science & Technology

1991-03-15

Lasing Properties of Nd3+:Ba2 ZnGe 2O 7 III. SPECTROSCOPIC PROPERTIES OF CHROMIUM -DOPED LASER CRYSTALS III.1 Laser-Induced Grating Spectroscopy of...rare earth- and chromium -doped Iasor crystals, rare earth-doped glasses, and potassium niobate. Ilas or- spectroscopy techniques were used to...being investigated: rare ea’-Lh-doped laser crystals; chromium -doped laser crystals; and photorefractive crystals and glasses. The important results

Microstructures and Surface Stabilities of {Ni-0.4C-6Ta- xCr, 0 ≤ x ≤ 50 Wt Pct} Cast Alloys at High Temperature

NASA Astrophysics Data System (ADS)

Berthod, Patrice

2018-06-01

Nickel-based cast alloys rich in chromium and reinforced by TaC carbides are potentially very interesting alloys for applications at elevated temperatures. Unfortunately, unlike cobalt-chromium and iron-chromium alloys, it is difficult to obtain exclusively TaC as primary carbides in Ni-Cr alloys. In alloys containing 30 wt pct Cr tantalum, carbides coexist with chromium carbides. The latter tend to weaken the alloy at elevated temperatures because they become rapidly spherical and then quickly lose their reinforcing effect. In this work, we attempted to stabilize TaC as a single carbide phase by testing different chromium contents in the [0, 50 wt pct] range. Six alloys containing 0.4C and 6Ta, weight contents corresponding to equivalent molar contents, were elaborated by foundry, and their as-cast microstructures were characterized. Samples of all alloys were exposed to 1127 °C and 1237 °C for 24 hours to characterize their stabilized microstructures. The surface fractions of chromium carbides and tantalum carbides were measured by image analysis, and their evolutions vs the chromium content were studied. For the chosen C and Ta contents, it appears that obtaining TaC only is possible by decreasing the chromium content to 10 wt pct. At the same time, TaC fractions are unfortunately too low because a large portion of tantalum integrates into the solid solution in the matrix. A second consequence is a critical decrease in oxidation resistance. Other possible methods to stabilize TaC as a single carbide are evocated, such as the simultaneous increase in Ta and decrease in chromium from 30 wt pct Cr.

Solid surface dependent layering of self-arranged structures with fibril-like assemblies of alpha-synuclein

NASA Astrophysics Data System (ADS)

Bukauskas, V.; Šetkus, A.; Šimkienė, I.; Tumėnas, S.; Kašalynas, I.; Rėza, A.; Babonas, J.; Časaitė, V.; Povilonienė, S.; Meškys, R.

2012-03-01

In present work the formation of hybrid constructions composed of alpha-synuclein-based colloidal solutions on various solid surfaces (silica coated Si, mica, CaF2 and KBr) is investigated by scanning probe microscopy, spectrocopic ellipsometry, Fourier transformed infrared spectroscopy and vibrational circular dichroism. Prior to the modification of the solids, the proteins were intentionally fibrilled under special conditions. It is proved that the multi-component coatings are self-arranged on the solid substrates. Depending on the substrate material, the interface films consisting of individual biomolecules can be detected on the solid surfaces. The coatings with fibril-like alpha-synuclein objects can be obtained on solid surfaces with negligible or comparatively thick interface films. The results are interpreted in terms of the charged surface-controlled electrostatic interaction between the substrate and the biomolecules. Solubility of solids is considered in this interpretation.

Removal of elevated level of chromium in groundwater by the fabricated PANI/Fe3O4 nanocomposites.

PubMed

Ramachandran, Aruna; Prasankumar, T; Sivaprakash, S; Wiston, Biny R; Biradar, Santhosh; Jose, Sujin

2017-03-01

In this work, we report the reduction of chromium concentration in the polluted groundwater samples from Madurai Kamaraj University area, India, where the dissolved salts in groundwater are reported as serious health hazards for its inhabitants. The water samples have intolerable amounts of total dissolved solids (TDS) and chromium is a prominent pollutant among them. Chromium reduction was achieved by treating the polluted groundwater with PANI/Fe 3 O 4 nanocomposites synthesized by in situ polymerization method. Further experimentation showed that the nanocomposites exhibit better chromium removal characteristics upon increasing the aniline concentration during the synthesis. We were able to reduce chromium concentration in the samples from 0.295 mg L -1 to a tolerable amount of 0.144 mg L -1 . This work is expected to open doors for chromium-free groundwater in various regions of India, when improved to an industrial scale.

Effects of chromium and aluminum on mechanical and oxidation properties of iron-nickel-base superalloys based on CG-27

NASA Technical Reports Server (NTRS)

Schuon, S. R.

1985-01-01

The effects of chromium and aluminum on the mechanical and oxidation properties of a series of gamma-prime-strengthened alloys based on CG-27 were studied. Gamma-prime dispersion and solid-solution strengthening were the principal modes of alloy strengthening. The oxidation attack parameter K sub a decreased with increasing Cr and Al contents for each alloy group based on Al content. As a group, alloys with 3 wt % Al had the lowest attack parameters. Therefore, 3 wt % is the optimum level of Al for parabolic oxidation behavior. Spalling, due to diffusion-induced grain growth, was controlled by the overall Cr and Al levels. The alloy with 4 wt % Cr and 3 wt % Al had stress-rupture properties superior to those of the base alloy, CG-27, and maintained parabolic oxidation behavior while the Cr content was reduced by two-thirds of its value in cast CG-27.

Preliminary Evaluation of PS300: A New Self-Lubricating High Temperature Composite Coating for Use to 800 C

NASA Technical Reports Server (NTRS)

Dellacorte, C.; Edmonds, B. J.

1995-01-01

This paper introduces PS300, a plasma sprayed, self-lubricating composite coating for use in sliding contacts at temperatures to 800 C. PS300 is a metal bonded chrome oxide coating with silver and BaF2/CaF2 eutectic solid lubricant additives. PS300 is similar to PS200, a chromium carbide based coating, which is currently being investigated for a variety of tribological applications. In pin-on-disk testing up to 650 C, PS300 exhibited comparable friction and wear properties to PS200. The PS300 matrix, which is predominantly chromium oxide rather than chromium carbide, does not require diamond grinding and polishes readily with silicon carbide abrasives greatly reducing manufacturing costs compared to PS200. It is anticipated that PS300 has potential for sliding bearing and seal applications in both aerospace and general industry.

Eutectics as improved pharmaceutical materials: design, properties and characterization.

PubMed

Cherukuvada, Suryanarayan; Nangia, Ashwini

2014-01-28

Eutectics are a long known class of multi-component solids with important and useful applications in daily life. In comparison to other multi-component crystalline solids, such as salts, solid solutions, molecular complexes and cocrystals, eutectics are less studied in terms of molecular structure organization and bonding interactions. Classically, a eutectic is defined based on its low melting point compared to the individual components. In this article, we attempt to define eutectics not just based on thermal methods but from a structural organization view point, and discuss their microstructures and properties as organic materials vis-a-vis solid solutions and cocrystals. The X-ray crystal structure of a cocrystal is different from that of the individual components whereas the unit cell of a solid solution is similar to that of one of the components. Eutectics are closer to the latter species in that their crystalline arrangement is similar to the parent components but they are different with respect to the structural integrity. A solid solution possesses structural homogeneity throughout the structure (single phase) but a eutectic is a heterogeneous ensemble of individual components whose crystal structures are like discontinuous solid solutions (phase separated). Thus, a eutectic may be better defined as a conglomerate of solid solutions. A structural analysis of cocrystals, solid solutions and eutectics has led to an understanding that materials with strong adhesive (hetero) interactions between the unlike components will lead to cocrystals whereas those having stronger cohesive (homo/self) interactions will more often give rise to solid solutions (for similar structures of components) and eutectics (for different structures of components). We demonstrate that the same crystal engineering principles which have been profitably utilized for cocrystal design in the past decade can now be applied to make eutectics as novel composite materials, illustrated by stable eutectics of the hygroscopic salt of the anti-tuberculosis drug ethambutol as a case study. A current gap in the characterization of eutectic microstructure may be fulfilled through pair distribution function (PDF) analysis of X-ray diffraction data, which could be a rapid signature technique to differentiate eutectics from their components.

CHROMIUM REMOVAL PROCESSES DURING GROUNDWATER REMEDIATION BY A ZEROVALENT IRON PERMEABLE REACTIVE BARRIER

EPA Science Inventory

Solid-phase associations of chromium were examined in core materials collected from a full-scale, zerovalent iron, permeable reactive barrier (PRB) at the U.S. Coast Guard Support Center located near Elizabeth City (NC). The PRB was installed in 1996 to treat groundwater contami...

Poultry feed based on protein hydrolysate derived from chrome-tanned leather solid waste: creating value from waste.

PubMed

Chaudhary, Rubina; Pati, Anupama

2016-04-01

Leather industry generates huge amount of chrome-containing leather solid waste which creates major environment problems to tanners worldwide. Chrome-tanned leather solid waste is primarily chromium complex of collagen protein. The presence of chromium limits its protein application in animal feed industry. The purified protein hydrolysate with zero chromium could be used in poultry feed. In this study, an attempt has been made to assess performance of poultry with purified protein hydrolysate as a feed derived from chrome-tanned leather waste as partial replacement of soyabean meal as a sole source of protein for growing broiler chickens. Growth study was conducted to evaluate the effect of feeding protein hydrolysate on performance and physiochemical characteristics of meat of broiler chickens. Two experimental diets containing various levels of protein hydrolysate (EI-20 % and EII-30 %) were evaluated. The comparative study was performed as control with soyabean meal. Daily feed intake, body weight gain and feed conversion ratio were measured from day 8 to day 35. At the end of the study, birds were randomly selected and slaughtered to evaluate for physiochemical characteristics of meat. Diet had significant effects on feed intake and body weight gain. Birds fed with 20 and 30 % protein hydrolysate consumed 9.5 and 17.5 % higher amount of feed and gained 6.5 and 16.6 % higher than soyabean meal-fed birds. The current study produced evidence that protein hydrolysate can replace up to 75 % of soyabean meal in broiler diets without affecting either growth performance or meat characteristics.

Complex coacervation of collagen hydrolysate extracted from leather solid wastes and chitosan for controlled release of lavender oil.

PubMed

Ocak, Buğra

2012-06-15

In the world, approximately 600,000 metric tonnes of chromium-containing solid wastes are generated by the leather industry each year. Environmental concerns and escalating landfill costs are becoming increasingly serious problems to the leather industry and seeking solutions to these problems is a prime concern in much research today. In this study, solid collagen-based protein hydrolysate was isolated from chromium-tanned leather wastes and its chemical properties were determined. Microcapsules of collagen hydrolysate (CH) - chitosan (C) crosslinked with glutaraldehyde (GA) containing Lavender oil (LO) were prepared by complex coacervation method. The effects of various processing parameters, including the CH to C ratio, LO content, and GA, on the oil load (%), oil content (%), encapsulation efficiency (%) and release rate of LO from microcapsules were investigated. As the ratio of C present in the CH/C mixture and crosslinking density increased, the release rate of LO from microcapsules slowed down. Optical and scanning electron microscopy images illustrated that the LO microcapsules were spherical in shape. Fourier transform infrared spectroscopy (FTIR) studies confirmed that there was no significant interaction between CH/C complex and LO. Copyright © 2012 Elsevier Ltd. All rights reserved.

Chromium uptake by rice and accumulation in soil amended with municipal solid waste compost.

PubMed

Bhattacharyya, P; Chakraborty, A; Chakrabarti, K; Tripathy, S; Powell, M A

2005-09-01

Effect of addition of municipal solid waste compost (MSWC) on chromium (Cr) content of submerged rice paddies was studied. Experiments were conducted during the three consecutive wet seasons from 1997 to 1999 on rice grown under submergence, at the Experimental Farm of Calcutta University, India. A sequential extraction method was used to determine the various chromium fractions in MSWC and cow dung manure (CDM). Chromium was significantly bound to the organic matter and Fe and Mn oxides in MSWC and CDM. Chromium content in rice straw was higher than in rice grain. Chromium bound with organic matter in MSWC best correlated with straw Cr (r=0.99**) followed by Fe and Mn oxides (r=0.97*) and water soluble as well as exchangeable fractions (r=0.96*). The water soluble and the exchangeable fractions in MSWC best correlated with grain Cr (r=0.98*). The Cr content of rice grain had the highest correlation with water soluble and exchangeable Cr (r=0.99**) while the straw Cr best correlated with the Fe and Mn oxides (r=0.98*). Both the carbonate bound and residual fractions in MSWC and CDM did not significantly correlate with rice straw and grain Cr. MSWC would be a valuable resource for agriculture if it can be used safely, but long-term use may require the cessation of the dumping by the leather tanneries and other major contributors of pollutants.

Microbial exudate promoted dissolution and transformation of chromium containing minerals

NASA Astrophysics Data System (ADS)

Saad, E. M.; Sun, J.; Tang, Y.

2015-12-01

Because of its utility in many industrial processes, chromium has become the second most common metal contaminant in the United States. The two most common oxidation states of chromium in nature are Cr(III), which is highly immobile, and Cr(VI), which is highly mobile and toxic. In both natural and engineered environments, the most common remediation of Cr(VI) is through reduction, which results in chromium sequestration in the low solubility mixed Cr(III)-Fe(III) (oxy)hydroxide phases. Consequently, the stability of these minerals must be examined to assess the fate of chromium in the subsurface. We examined the dissolution of mixed Cr(III)-Fe(III) (oxy)hydroxides in the presence of common microbial exudates, including the siderophore desferrioxamine B (DFOB; a common organic ligand secreted by most microbes with high affinity for ferric iron and other trivalent metal ions) and oxalate (a common organic acid produced by microbes). The solids exhibited incongruent dissolution with preferential leaching of Fe from the solid phase. Over time, this leads to a more Cr rich mineral, which is known to be more soluble than the corresponding mixed mineral phase. We are currently investigating the structure of the reacted mineral phases and soluble Cr(III) species, as well as the potential oxidation and remobilization of the soluble Cr species. Results from this study will provide insights regarding the long term transport and fate of chromium in the natural environment in the presence of microbial activities.

Quantitative determination of chromium picolinate in animal feeds by solid phase extraction and liquid chromatography-tandem mass spectrometry.

PubMed

Han, Miaomiao; Tian, Ying; Li, Zhen; Chen, Yiqiang; Yang, Wenjun; Zhang, Liying

2017-12-01

Chromium picolinate is one of the important Cr 3+ resources and is widely used in animal production. A convenient, reliable and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitative determination of chromium picolinate in animal feeds. Feed samples were extracted with acetonitrile and subsequently cleaned up by solid phase extraction cartridges Supelclean™ LC-18. Chromium picolinate was efficiently separated with a Waters ACQUITY UPLC ® BEH C18 column, ionized with electrospray ion source in positive mode (ESI + ), and quantitatively determined by tandem mass spectrometry in multiple reaction monitoring mode. Standard calibration curve of chromium picolinate in the concentration range from 0.5 to 1000ng/mL was obtained with good linearity correlation coefficient (R 2 =0.9982). Average recoveries ranged from 95.37%∼105.54%, as detected by spiking 0.02∼640mg/kg of chromium picolinate in complete feed, concentrated feed and premix. Intra-day and inter-day coefficient of variation were 0.59%∼6.67% and 2.36%∼6.97%, respectively. The limits of quantitation were 0.02mg/kg, 0.025mg/kg, and 2mg/kg for complete feed, concentrated feed, and premix, respectively. Actual sample analysis indicated that the developed method can be an effective tool to monitoring CrPic content in animal feed. Copyright © 2017. Published by Elsevier B.V.

Chemical and microbial remediation of hexavalent chromium from contaminated soil and mining/metallurgical solid waste: a review.

PubMed

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

2013-04-15

Chromium is a highly toxic non-essential metal for microorganisms and plants, and its occurrence is rare in nature. Lower to higher chromium containing effluents and solid wastes released by activities such as mining, metal plating, wood preservation, ink manufacture, dyes, pigments, glass and ceramics, tanning and textile industries, and corrosion inhibitors in cooling water, induce pollution and may cause major health hazards. Besides, natural processes (weathering and biochemical) also contribute to the mobility of chromium which enters in to the soil affecting the plant growth and metabolic functions of the living species. Generally, chemical processes are used for Cr- remediation. However, with the inference derived from the diverse Cr-resistance mechanism displayed by microorganisms and the plants including biosorption, diminished accumulation, precipitation, reduction of Cr(VI) to Cr(III), and chromate efflux, bioremediation is emerging as a potential tool to address the problem of Cr(VI) pollution. This review focuses on the chemistry of chromium, its use, and toxicity and mobility in soil, while assessing its concentration in effluents/wastes which becomes the source of pollution. In order to conserve the environment and resources, the chemical/biological remediation processes for Cr(VI) and their efficiency have been summarised in some detail. The interaction of chromium with various microbial/bacterial strains isolated and their reduction capacity towards Cr(VI) are also discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

Host Materials for Transition-Metal Ions with the ndN Electronic Configuration.

DTIC Science & Technology

1985-10-01

B. Manson, G. A. Shah, B. Howes, and C. D. Flint, 4A9 - Spectrum of Chromium - Doped Ammonium Aluminum Sulphate,2E Transition of Mn4 in Cs2 TiF 6.MnF6... Chromium Spinels , J. Phys. Chem. Solids 27 (1966),adVS.evsynSp-LtieRlxioofC3Insn 1379.Emerald, Soy. Phys. Solid State 22 (1980), 563. (15) W. Low...3d3 Sviridov, and 1. N. Kalinkina, Absoroption Spectra and Calculation Cr 3 -24,350 5376 4,2 - 3 10 d3 of Energy-Level Diagram of Fe3+ and Mn 24

Experimental research results of solid particle erosion resistance of blade steel with protective coating

NASA Astrophysics Data System (ADS)

Kachalin, G. V.; Mednikov, A. F.; Tkhabisimov, A. B.; Seleznev, L. I.

2017-11-01

The paper presents the results of metallographic studies and solid particle erosion tests of uncoated blade steel 20kH13 samples and samples with a protective coating based on chromium carbide (Cr-CrC) at a flow (air) velocity CA = 180 m/s, flow temperature tA = 25 °C, attack angle α = 30° and consumption of solid abrasive particles GP = 5·10-4 kg/s. It was found that the coating has a granular structure, a thickness is about 11 μm, the microhardness of the surface is 1520 ± 50 HV0.05. Processing of the obtained data by statistical analysis methods showed that the protective coating based on Cr-CrC increases the solid particle erosion resistance of the blade steel 20kH13 by the incubation-transitional period duration more than 2.5 times.

Simultaneous speciation analysis of inorganic arsenic, chromium and selenium in environmental waters by 3-(2-aminoethylamino) propyltrimethoxysilane modified multi-wall carbon nanotubes packed microcolumn solid phase extraction and ICP-MS.

PubMed

Peng, Hanyong; Zhang, Nan; He, Man; Chen, Beibei; Hu, Bin

2015-01-01

Speciation analysis of inorganic arsenic, chromium and selenium in environmental waters is of great significance for the monitoring of environmental pollution. In this work, 3-(2-aminoethylamino) propyltrimethoxysilane (AAPTS) functionalized multi-wall carbon nanotubes (MWCNTs) were synthesized and employed as the adsorbent for simultaneous speciation analysis of inorganic arsenic, chromium and selenium in environmental waters by microcolumn solid-phase extraction (SPE)-inductively coupled plasma mass spectrometry (ICP-MS). It was found that As(V), Cr(VI) and Se(VI) could be selectively adsorbed on the microcolumn packed with AAPTS-MWCNTs adsorbent at pH around 2.2, while As(III), Cr(III) and Se(IV) could not be retained at this pH and passed through the microcolumn directly. Total inorganic arsenic, chromium and selenium was determined after the oxidation of As(III), Cr(III) and Se(IV) to As(V), Cr(VI) and Se(VI) with 10.0 μmol L(-1) KMnO4. The assay of As(III), Cr(III) and Se(IV) was based on subtracting As(V), Cr(VI) and Se(VI) from the total As, Cr and Se, respectively. Under the optimized conditions, the detection limits of 15, 38 and 16 ng L(-1) with the relative standard deviations (RSDs) of 7.4, 2.4 and 6.2% (c=1 µg L(-1), n=7) were obtained for As(V), Cr(VI) and Se(VI), respectively. The developed method was validated by analyzing four Certified Reference Materials, rainwater, Yangtze River and East Lake waters. Copyright © 2014 Elsevier B.V. All rights reserved.

A solid-state NMR method to determine domain sizes in multi-component polymer formulations

NASA Astrophysics Data System (ADS)

Schlagnitweit, Judith; Tang, Mingxue; Baias, Maria; Richardson, Sara; Schantz, Staffan; Emsley, Lyndon

2015-12-01

Polymer domain sizes are related to many of the physical properties of polymers. Here we present a solid-state NMR experiment that is capable of measuring domain sizes in multi-component mixtures. The method combines selective excitation of carbon magnetization to isolate a specific component with proton spin diffusion to report on domain size. We demonstrate the method in the context of controlled release formulations, which represents one of today's challenges in pharmaceutical science. We show that we can measure domain sizes of interest in the different components of industrial pharmaceutical formulations at natural isotopic abundance containing various (modified) cellulose derivatives, such as microcrystalline cellulose matrixes that are film-coated with a mixture of ethyl cellulose (EC) and hydroxypropyl cellulose (HPC).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, Ashutosh; Dwivedi, Jagrati, E-mail: hemu.dwi@gmail.com; Shukla, Kritika

Five Chromium (III) complexes have been prepared using Schiff base ligands which derived from benzoin and five different amino acids (H{sub 2}N-R). Samples were characterized by XRD, FTIR, UV-VIS and SEM method. X-Ray diffraction pattern analyzed that all chromium (III) complexes have hexagonal structure and crystalline, in nature, using Bruker D8 Advance instrument. Using VERTAX 70, FTIR spectroscopy reveals that Samples have (C=N), (C-O), (M-N) and (M-O) bonds in the range of 4000-400cm{sup −1}. UV-VIS spectroscopy give information that samples absorb the visible light which is in the range of 380-780nm. For this, Lambda 960 spectrometer used. SEM is designedmore » for studying of the solid objects, using JEOL JSM 5600 instrument.« less

Field method for the determination of hexavalent chromium by ultrasonication and strong anion-exchange solid-phase extraction.

PubMed

Wang, J; Ashley, K; Marlow, D; England, E C; Carlton, G

1999-03-01

A simple, fast, sensitive, and economical field method was developed and evaluated for the determination of hexavalent chromium (CrVI) in environmental and workplace air samples. By means of ultrasonic extraction in combination with a strong anion-exchange solid-phase extraction (SAE-SPE) technique, the filtration, isolation, and determination of CrVI in the presence of trivalent chromium (CrIII) and potential interferents was achieved. The method entails (1) ultrasonication in basic ammonium buffer solution to extract CrVI from environmental matrixes; (2) SAE-SPE to separate CrVI from CrIII and interferences; (3) elution/acidification of the eluate; (4) complexation of chromium with 1,5-diphenylcarbazide; and (5) spectrophotometric determination of the colored chromium-diphenylcarbazone complex. Several critical parameters were optimized in order to effect the extraction of both soluble (K2CrO4) and insoluble (PbCrO4) forms of CrVI without inducing CrIII oxidation or CrVI reduction. The method allowed for the dissolution and purification of CrVI from environmental and workplace air sample matrixes for up to 24 samples simultaneously in less than 90 min (including ultrasonication). The results demonstrated that the method was simple, fast, quantitative, and sufficiently sensitive for the determination of occupational exposures of CrVI. The method is applicable for on-site monitoring of CrVI in environmental and industrial hygiene samples.

Hot-Tearing Assessment of Multicomponent Nongrain-Refined Al-Cu Alloys for Permanent Mold Castings Based on Load Measurements in a Constrained Mold

NASA Astrophysics Data System (ADS)

Sabau, Adrian S.; Mirmiran, Seyed; Glaspie, Christopher; Li, Shimin; Apelian, Diran; Shyam, Amit; Allen Haynes, J.; Rodriguez, Andres F.

2018-06-01

The hot-tearing resistance of multicomponent Al-Cu alloys during permanent mold casting was investigated using a constrained permanent mold in which the load and temperature were measured. The nominal Cu composition was varied from 5 to 8 wt pct. Casting experiments were conducted without adding any grain-refining inoculants. The following variables, which were obtained from the measured load data during casting, were considered to assess the hot-tearing resistance of the Al-Cu multicomponent alloys: "V"-like signature in the load rate variation, load at solidus point, and load rate average over the freezing range. In addition, a hot-tearing criterion based on the variation of the fraction of solid in the late stages of solidification was used. It was found that all criteria considered can accurately predict the alloys with the lowest and highest hot-tear resistance, respectively. It was found that the rate of measured load during casting could be used to indicate substantial hot tearing. However, the load rate variation could not be used to detect when small hot tears were present. Among all the criteria considered, the load at the solidus point shows an excellent agreement with experimentally observed hot-tearing resistance for all but one alloy. The poorly resistant hot-tearing alloys exhibited mainly coarse columnar grains while the most hot-tearing resistant alloys exhibited a much more refined grain microstructure. This is the first study in which good hot-tear resistance is demonstrated for multicomponent Al-Cu alloys with nominal Cu content greater than 7 wt pct.

Spectroscopic and Thermal Behavior of Chromium Soaps

NASA Astrophysics Data System (ADS)

Mehrotra, K. N.; Jain, Mamta

1996-02-01

The physicochemical characteristics of chromium soaps (myristate and stearate) were investigated in the solid state (thermal, X-ray, and IR measurements) and in solutions (spectrophotometric measurements). The thermal measurements showed that the decomposition of chromium soaps is a two-step process. The soap decomposed into chromium oxycarboxylate, ketone, and carbon dioxide in the first step and the intermediate oxycarboxylate underwent further decomposition to chromium trioxide in the second step. The results showed that the second step is kinetically of zero order and the values of energy of activation for the first and second steps lie in the ranges 6-7 and 17-18 kcal mol-1, respectively. The X-ray diffraction results showed that these soaps possess double-layer structure with molecular axes slightly inclined to the basal plane. The infrared results revealed that the fatty acids exist with dimeric structure through hydrogen bonding between two molecules of fatty acids whereas the metal-to-oxygen bonds in chromium soaps are not purely ionic but possess considerable covalent character. The results of spectrophotometric measurements also confirmed the somewhat covalent nature of chromium soaps in solutions in dichloromethane.

Spectroscopic, structural characterizations and antioxidant capacity of the chromium (III) niacinamide compound as a diabetes mellitus drug model

NASA Astrophysics Data System (ADS)

Refat, Moamen S.; El-Megharbel, Samy M.; Hussien, M. A.; Hamza, Reham Z.; Al-Omar, Mohamed A.; Naglah, Ahmed M.; Afifi, Walid M.; Kobeasy, Mohamed I.

2017-02-01

New binuclear chromium (III) niacinamide compound with chemical formula [Cr2(Nic)(Cl)6(H2O)4]·H2O was obtained upon the reaction of chromium (III) chloride with niacinamide (Nic) in methanol solvent at 60 °C. The proposed structure was discussed with the help of microanalytical analyses, conductivity, spectroscopic (FT-IR and UV-vis.), magnetic calculations, thermogravimetric analyses (TG/TGA), and morphological studies (X-ray of solid powder and scan electron microscopy. The infrared spectrum of free niacinamide in comparison with its chromium (III) compound indicated that the chelation mode occurs via both nitrogen atoms of pyridine ring and primary -NH2 group. The efficiency of chromium (III) niacinamide compound in decreasing of glucose level of blood and HbA1c in case of diabetic rats was checked. The ameliorating gluconeogenic enzymes, lipid profile and antioxidant defense capacities are considered as an indicator of the efficiency of new chromium (III) compound as antidiabetic drug model.

Processes affecting the remediation of chromium-contaminated sites.

PubMed

Palmer, C D; Wittbrodt, P R

1991-05-01

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 precipitation/dissolution reactions control the transformation and mobility of chromium. The reduction of CrVI to CrIII can occur in the presence of ferrous iron in solution or in mineral phases, reduced sulfur compounds, or soil organic matter. At neutral to alkaline pH, the CrIII precipitates as amorphous hydroxides or forms complexes with organic matter. CrIII is oxidized by manganese dioxide, a common mineral found in many soils. Solid-phase precipitates of hexavalent chromium such as barium chromate can serve either as sources or sinks for CrVI. Adsorption of CrVI in soils increases with decreasing chromium concentration, making it more difficult to remove the chromium as the concentration decreases during pump-and-treat remediation. Knowledge of these chemical and physical processes is important in developing and selecting effective, cost-efficient remediation designs for chromium-contaminated sites.

Tensile Properties and Structure of Several Superalloys after Long- Term Exposure to LiF and Vacuum at 1173 K

NASA Astrophysics Data System (ADS)

Whittenberger, J. D.

1995-12-01

The use of the solid- to- liquid phase transformation of LiF to store thermal energy is under consideration for a space- based solar dynamic system. Although advantageous in terms of its energy density, the melting point of this salt (1121K) is beyond the commonly accepted upper- use temperature of 1100 K for chromium- bearing superalloys in vacuum. However, one commercially available nickel- base superalloy (Hastelloy B- 2) is chromium free; unfortunately, because of its high molybdenum content, this alloy can form phases that cause high- temperature embrittlement. To test the suitability of Hastelloy B- 2, it has been exposed to molten LiF, its vapor and vacuum at 1173 K for 2500, 5000, and 10 h. For control, the chromium- containing cobalt- base Haynes alloy 188 and nickel- base Haynes alloy 230 were also exposed to LiF and vacuum at 1173 K for 5000 h. Neither LiF nor vacuum exposures had any significant effect on Hastelloy B- 2 in terms of microstructural surface damage or weight change. Measurement of the post exposure tensile properties of Hastelloy B- 2, nevertheless, revealed low tensile ductility at 1050 K. Such embrittlement and low strength at elevated temperatures appear to preclude the use of Hastelloy B- 2 as a containment material for LiF. Little evidence of significant attack by LiF was seen in either of the chromium- containing superalloys; however, considerable weight loss and near- surface microstructural damage occurred in both alloys exposed to vacuum. Although measurement of the post exposure room-temperature tensile properties of Haynes alloys 188 and 230 revealed no significant loss of strength or ductility, the severe degree of microstructural damage found in unshielded alloys exposed to vacuum indicates that chromium-bearing superalloys might also be unsuitable for prolonged containment of LiF in space above 1100 K. Keywords

Solid waste from leather industry as adsorbent of organic dyes in aqueous-medium.

PubMed

Oliveira, Luiz C A; Gonçalves, Maraísa; Oliveira, Diana Q L; Guerreiro, Mário C; Guilherme, Luiz R G; Dallago, Rogério M

2007-03-06

The industrial tanning of leather usually produces considerable amounts of chromium-containing solid waste and liquid effluents and raises many concerns on its environmental effect as well as on escalating landfill costs. Actually, these shortcomings are becoming increasingly a limiting factor to this industrial activity that claims for alternative methods of residue disposals. In this work, it is proposed a novel alternative destination of the solid waste, based on the removal of organic contaminants from the out coming aqueous-residue. The adsorption isotherm pattern for the wet blue leather from the Aurea tanning industry in Erechim-RS (Brazil) showed that these materials present high activity on adsorbing the reactive red textile dye as well as other compounds. The adsorbent materials were characterized by IR spectroscopy and SEM and tested for the dye adsorption (reactive textile and methylene blue dyes). The concentrations of dyes were measured by UV-vis spectrophotometry and the chromium extraction from leather waste was realized by basic hydrolysis and determined by atomic absorption. As a low cost abundant adsorbent material with high adsorption ability on removing dye methylene blue (80mgg(-1)) and textile dye reactive red (163mgg(-1)), the leather waste is revealed to be a interesting alternative relatively to more costly adsorbent materials.

Environmental exposure to chromium compounds in the valley of León, México.

PubMed Central

Armienta-Hernández, M A; Rodríguez-Castillo, R

1995-01-01

The effects on the environment and health of the operation of a chromate compounds factory and tanneries in the León valley in central México are discussed. Sampling and analysis of chromium were performed in water, soil, and human urine. Groundwater has been polluted in an area of about 5 km2 by the leaching of a solid factory waste, which results in concentrations up to 50 mg/l of hexavalent chromium. The plume shape and extension appear to be controlled by the prevailing well extraction regime. Total chromium was detected in the soil around the factory as a result of both aerial transport and deposition of dust produced in the chromate process and irrigation with tannery-contaminated water. Analysis of the impact of chromium in air and water on populations with various degrees of exposure revealed that highly harmful health effects were not observed. PMID:7621799

Determination of heavy metal toxicity of finished leather solid waste.

PubMed

Aslan, Ahmet

2009-05-01

This paper investigates the toxicity in leather products of heavy metals known to be detrimental to the ecosystem. Heavy metal concentrations in leather samples were identified with ICP-OES, and toxicity was determined using a MetPLATE bioassay. Chromium and aluminium were found to constitute 98% of the total concentration of heavy metals in finished leather tanned with chromium and aluminium salts, while in some vegetable-tanned leather, zirconium was the only heavy metal identified. The average inhibition values for chromium, aluminium and vegetable tanned leather were 98.08%, 97.04% and 62.36%, respectively.

Sedimentation Time Measurements of Soil Particles by Light Scattering and Determination of Chromium, Lead, and Iron in Soil Samples via ICP

ERIC Educational Resources Information Center

Todebush, Patricia Metthe; Geiger, Franz M.

2005-01-01

The study of soil samples, using light scattering and Inductively Coupled Plasma spectrometry (ICP) to determine colloid sedimentation rates and the quantity of chromium, lead, and iron in the sample is described. It shows the physical and chemical behavior of solid components in soil, and how such pollutant binding colloid surfaces directly…

Modelling of the Thermo-Physical and Physical Properties for Solidification of Al-Alloys

NASA Astrophysics Data System (ADS)

Saunders, N.; Li, X.; Miodownik, A. P.; Schillé, J.-P.

The thermo-physical and physical properties of the liquid and solid phases are critical components in casting simulations. Such properties include the fraction solid transformed, enthalpy release, thermal conductivity, volume and density, all as a function of temperature. Due to the difficulty in experimentally determining such properties at solidification temperatures, little information exists for multi-component alloys. As part of the development of a new computer program for modelling of materials properties (JMatPro) extensive work has been carried out on the development of sound, physically based models for these properties. Wide ranging results will presented for Al-based alloys, which will include more detailed information concerning the density change of the liquid that intrinsically occurs during solidification due to its change in composition.

Solid-Liquid Interface Thermal Resistance Affects the Evaporation Rate of Droplets from a Surface: A Study of Perfluorohexane on Chromium Using Molecular Dynamics and Continuum Theory.

PubMed

Han, Haoxue; Schlawitschek, Christiane; Katyal, Naman; Stephan, Peter; Gambaryan-Roisman, Tatiana; Leroy, Frédéric; Müller-Plathe, Florian

2017-05-30

We study the role of solid-liquid interface thermal resistance (Kapitza resistance) on the evaporation rate of droplets on a heated surface by using a multiscale combination of molecular dynamics (MD) simulations and analytical continuum theory. We parametrize the nonbonded interaction potential between perfluorohexane (C 6 F 14 ) and a face-centered-cubic solid surface to reproduce the experimental wetting behavior of C 6 F 14 on black chromium through the solid-liquid work of adhesion (quantity directly related to the wetting angle). The thermal conductances between C 6 F 14 and (100) and (111) solid substrates are evaluated by a nonequilibrium molecular dynamics approach for a liquid pressure lower than 2 MPa. Finally, we examine the influence of the Kapitza resistance on evaporation of droplets in the vicinity of a three-phase contact line with continuum theory, where the thermal resistance of liquid layer is comparable with the Kapitza resistance. We determine the thermodynamic conditions under which the Kapitza resistance plays an important role in correctly predicting the evaporation heat flux.

The nature of temper brittleness of high-chromium ferrite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarrak, V.I.; Suvorova, S.O.; Golovin, I.S.

The reasons for development of {open_quotes}475{degrees}C brittleness{close_quotes} of high-chromium ferritic steels are considered from the standpoint of fracture mechanics. It is shown that the general rise in the curve of temperature-dependent local flow stress has the decisive influence on the position of the ductile-to-brittle transformation temperature and the increase in it as the result of a hold at temperatures of development of brittleness. The established effect is related to the change in the parameters determining dislocation mobility, that is, the activation energy of dislocation movement in high-chromium ferrite and the resistance to microplastic deformation, both caused by processes of separationmore » into layers of high-chromium ferrite and decomposition of the interstitial solid solution.« less

Thermodynamic description of multicomponent nickel-base superalloys containing aluminum, chromium, ruthenium and platinum: A computational thermodynamic approach coupled with experiments

NASA Astrophysics Data System (ADS)

Zhu, Jun

Ru and Pt are candidate additional component for improving the high temperature properties of Ni-base superalloys. A thermodynamic description of the Ni-Al-Cr-Ru-Pt system, serving as an essential knowledge base for better alloy design and processing control, was developed in the present study by means of thermodynamic modeling coupled with experimental investigations of phase equilibria. To deal with the order/disorder transition occurring in the Ni-base superalloys, a physical sound model, Cluster/Site Approximation (CSA) was used to describe the fcc phases. The CSA offers computational advantages, without loss of accuracy, over the Cluster Variation Method (CVM) in the calculation of multicomponent phase diagrams. It has been successfully applied to fcc phases in calculating technologically important Ni-Al-Cr phase diagrams. Our effort in this study focused on the two key ternary systems: Ni-Al-Ru and Ni-Al-Pt. The CSA calculated Ni-Al-Ru ternary phase diagrams are in good agreement with the experimental results in the literature and from the current study. A thermodynamic description of quaternary Ni-Al-Cr-Ru was obtained based on the descriptions of the lower order systems and the calculated results agree with experimental data available in literature and in the current study. The Ni-Al-Pt system was thermodynamically modeled based on the limited experimental data available in the literature and obtained from the current study. With the help of the preliminary description, a number of alloy compositions were selected for further investigation. The information obtained was used to improve the current modeling. A thermodynamic description of the Ni-Al-Cr-Pt quaternary was then obtained via extrapolation from its constituent lower order systems. The thermodynamic description for Ni-base superalloy containing Al, Cr, Ru and Pt was obtained via extrapolation. It is believed to be reliable and useful to guide the alloy design and further experimental investigation.

Hot-Tearing Assessment of Multicomponent Nongrain-Refined Al-Cu Alloys for Permanent Mold Castings Based on Load Measurements in a Constrained Mold

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sabau, Adrian S.; Mirmiran, Seyed; Glaspie, Christopher

Here, the hot-tearing resistance of multicomponent Al-Cu alloys during permanent mold casting was investigated using a constrained permanent mold in which the load and temperature were measured. The nominal Cu composition was varied from 5 to 8 wt pct. Casting experiments were conducted without adding any grain-refining inoculants. The following variables, which were obtained from the measured load data during casting, were considered to assess the hot-tearing resistance of the Al-Cu multicomponent alloys: “V”-like signature in the load rate variation, load at solidus point, and load rate average over the freezing range. In addition, a hot-tearing criterion based on themore » variation of the fraction of solid in the late stages of solidification was used. It was found that all criteria considered can accurately predict the alloys with the lowest and highest hot-tear resistance, respectively. It was found that the rate of measured load during casting could be used to indicate substantial hot tearing. However, the load rate variation could not be used to detect when small hot tears were present. Among all the criteria considered, the load at the solidus point shows an excellent agreement with experimentally observed hot-tearing resistance for all but one alloy. The poorly resistant hot-tearing alloys exhibited mainly coarse columnar grains while the most hot-tearing resistant alloys exhibited a much more refined grain microstructure. This is the first study in which good hot-tear resistance is demonstrated for multicomponent Al-Cu alloys with nominal Cu content greater than 7 wt pct.« less

Hot-Tearing Assessment of Multicomponent Nongrain-Refined Al-Cu Alloys for Permanent Mold Castings Based on Load Measurements in a Constrained Mold

DOE PAGES

Sabau, Adrian S.; Mirmiran, Seyed; Glaspie, Christopher; ...

2018-02-16

Here, the hot-tearing resistance of multicomponent Al-Cu alloys during permanent mold casting was investigated using a constrained permanent mold in which the load and temperature were measured. The nominal Cu composition was varied from 5 to 8 wt pct. Casting experiments were conducted without adding any grain-refining inoculants. The following variables, which were obtained from the measured load data during casting, were considered to assess the hot-tearing resistance of the Al-Cu multicomponent alloys: “V”-like signature in the load rate variation, load at solidus point, and load rate average over the freezing range. In addition, a hot-tearing criterion based on themore » variation of the fraction of solid in the late stages of solidification was used. It was found that all criteria considered can accurately predict the alloys with the lowest and highest hot-tear resistance, respectively. It was found that the rate of measured load during casting could be used to indicate substantial hot tearing. However, the load rate variation could not be used to detect when small hot tears were present. Among all the criteria considered, the load at the solidus point shows an excellent agreement with experimentally observed hot-tearing resistance for all but one alloy. The poorly resistant hot-tearing alloys exhibited mainly coarse columnar grains while the most hot-tearing resistant alloys exhibited a much more refined grain microstructure. This is the first study in which good hot-tear resistance is demonstrated for multicomponent Al-Cu alloys with nominal Cu content greater than 7 wt pct.« less

A MIXED CHEMICAL REDUCTANT FOR TREATING HEXAVALENT CHROMIUM IN A CHROMITE ORE PROCESSING SOLID WASTE

EPA Science Inventory

We evaluated a method for delivering ferrous iron into the subsurface to enhance chemical reduction of Cr(VI) in a chromite ore processing solid waste (COPSW). The COPSW is characterized by high pH (8.5 -11.5), high Cr(VI) concentrations in the solid phase (up to 550 mg kg-1) and...

Assessing the impact of geogenic chromium uptake by carrots (Daucus carota) grown in Asopos river basin.

PubMed

Lilli, Maria A; Syranidou, Evdokia; Palliou, Andriana; Nikolaidis, Nikolaos P; Karatzas, George; Kalogerakis, Nicolas

2017-01-01

A methodology was developed to assess the impact of geogenic origin hexavalent chromium uptake by carrots, and the risk of human consumption of carrots grown in Asopos River basin in Greece. A field scale experiment was conducted with carrots cultivated in treatment plots, with and without compost amendment, in order to assess the impact of carbon in the mobility and uptake of chromium by plants. The results suggested that there is a trend for chromium mobilization and uptake in the surface and the leaves of the carrots cultivated in the treatment plot with the higher carbon addition, but not in the core of the carrots. Limited mobility of hexavalent chromium in the soil-plant-water system is presented due to the affinity of chromium to be retained in the solid phase and be uptaken by plants. Hexavalent chromium tolerant bacterial strains were isolated from the carrots. These endophytic bacteria, present in all parts of the plant, were able to reduce hexavalent chromium to trivalent form to levels below the detection limit. Finally, a site-specific risk assessment analysis suggested no adverse effects to human health due to the consumption of carrots. These findings are of particular importance since they confirm that carrots grown in soils with geogenic origin chromium does not pose any adverse risk for human consumption, but could also have the beneficial effect of the micronutrient trivalent chromium. Copyright © 2016 Elsevier Inc. All rights reserved.

Method of doping interconnections for electrochemical cells

DOEpatents

Pal, Uday B.; Singhal, Subhash C.; Moon, David M.; Folser, George R.

1990-01-01

A dense, electronically conductive interconnection layer 26 is bonded on a porous, tubular, electronically conductive air electrode structure 16, optionally supported by a ceramic support 22, by (A) forming a layer of oxide particles of at least one of the metals Ca, Sr, Co, Ba or Mg on a part 24 of a first surface of the air electrode 16, (B) heating the electrode structure, (C) applying a halide vapor containing at least lanthanum halide and chromium halide to the first surface and applying a source of oxygen to a second opposite surface of the air electrode so that they contact at said first surface, to cause a reaction of the oxygen and halide and cause a dense lanthanum-chromium oxide structure to grow, from the first electrode surface, between and around the oxide particles, where the metal oxide particles get incoporated into the lanthanum-chromium oxide structure as it grows thicker with time, and the metal ions in the oxide particles diffuse into the bulk of the lanthamum-chromium oxide structure, to provide a dense, top, interconnection layer 26 on top of the air electrode 16. A solid electrolyte layer 18 can be applied to the uncovered portion of the air electrode, and a fuel electrode 20 can be applied to the solid electrolyte, to provide an electrochemical cell 10.

Analysis of thermoelectric properties of high-temperature complex alloys of nickel-base, iron-base and cobalt-base groups

NASA Technical Reports Server (NTRS)

Holanda, R.

1984-01-01

The thermoelectric properties alloys of the nickel-base, iron-base, and cobalt-base groups containing from 1% to 25% 106 chromium were compared and correlated with the following material characteristics: atomic percent of the principle alloy constituent; ratio of concentration of two constituents; alloy physical property (electrical resistivity); alloy phase structure (percent precipitate or percent hardener content); alloy electronic structure (electron concentration). For solid-solution-type alloys the most consistent correlation was obtained with electron concentration, for precipitation-hardenable alloys of the nickel-base superalloy group, the thermoelectric potential correlated with hardener content in the alloy structure. For solid-solution-type alloys, no problems were found with thermoelectric stability to 1000; for precipitation-hardenable alloys, thermoelectric stability was dependent on phase stability. The effects of the compositional range of alloy constituents on temperature measurement uncertainty are discussed.

Effects of silver and group II fluoride solid lubricant additions to plasma-sprayed chromium carbide coatings for foil gas bearings to 650 C

NASA Technical Reports Server (NTRS)

Wagner, R. C.; Sliney, Harold E.

1986-01-01

A new self-lubricating coating composition of nickel aluminide-bonded chromium carbide formulated with silver and Group II fluorides was developed in a research program on high temperature solid lubricants. One of the proposed applications for this new coating composition is as a wide temperature spectrum solid lubricant for complaint foil gas bearings. Friction and wear properties were obtained using a foil gas bearing start-stop apparatus at temperatures from 25 to 650 C. The journals were Inconel 748. Some were coated with the plasma sprayed experimental coating, others with unmodified nickel aluminide/chromium carbide as a baseline for comparison. The additional components were provided to assist in achieving low friction over the temperature range of interest. Uncoated, preoxidized Inconel X-750 foil bearings were operated against these surfaces. The foils were subjected to repeated start/stop cycles under a 14-kPa (2-Psi) bearing unit loading. Sliding contact occurred during lift-off and coastdown at surface velocities less than 6 m/s (3000 rPm). Testing continued until 9000 start/stop cycles were accumulated or until a rise in starting torque indicated the journal/bearing had failed. Comparison in coating performance as well as discussions of their properties and methods of application are given.

Effects of silver and group 2 fluorides addition to plasma sprayed chromium carbide high temperature solid lubricant for foil gas bearing to 650 deg C

NASA Technical Reports Server (NTRS)

Wagner, R. C.; Sliney, H. E.

1984-01-01

A new self-lubricating coating composition of nickel aluminide-bonded chromium carbide formulated with silver and Group II fluorides was developed in a research program on high temperature solid lubricants. One of the proposed applications for this new coating composition is as a wide temperature spectrum solid lubricant for complaint foil gas bearings. Friction and wear properties were obtained using a foil gas bearing start/stop apparatus at temperatures from 25 to 650 C. The journals were Inconel 718. Some were coated with the plasma sprayed experimental coating, others with unmodified nickel aluminide/chromium carbide as a baseline for comparison. The addtitional components were provided to assist in achieving low friction over the temperature range of interest. Uncoated, preoxidized Inconel X-750 foil bearings were operated against these surfaces. The foils were subjected to repeated start/stop cycles under a 14-kPa (2-psi) bearing unit loading. Sliding contact occurred during lift-off and coastdown at surface velocities less than 6 m/s (3000 rpm). Testing continued until 9000 start/stop cycles were accumulated or until a rise in starting torque indicated the journal/bearing had failed. Comparison in coating performance as well as discussions of their properties and methods of application are given.

Vacuum-assisted headspace-solid phase microextraction for determining volatile free fatty acids and phenols. Investigations on the effect of pressure on competitive adsorption phenomena in a multicomponent system.

PubMed

Trujillo-Rodríguez, María J; Pino, Verónica; Psillakis, Elefteria; Anderson, Jared L; Ayala, Juan H; Yiantzi, Evangelia; Afonso, Ana M

2017-04-15

This work proposes a new vacuum headspace solid-phase microextraction (Vac-HSSPME) method combined to gas chromatography-flame ionization detection for the determination of free fatty acids (FFAs) and phenols. All target analytes of the multicomponent solution were volatiles but their low Henry's Law constants rendered them amenable to Vac-HSSPME. The ability of a new and easy to construct Vac-HSSPME sampler to maintain low-pressure conditions for extended sampling times was concurrently demonstrated. Vac-HSSPME and regular HSSPME methods were independently optimized and the results were compared at all times. The performances of four commercial SPME fibers and two polymeric ionic liquid (PIL)-based SPME fibers were evaluated and the best overall results were obtained with the adsorbent-type CAR/PDMS fiber. For the concentrations used here, competitive displacement became more intense for the smaller and more volatile analytes of the multi-component solution when lowering the sampling pressure. The extraction time profiles showed that Vac-HSSPME had a dramatic positive effect on extraction kinetics. The local maxima of adsorbed analytes recorded with Vac-HSSPME occurred faster, but were always lower than that with regular HSSPME due to the faster analyte-loading from the multicomponent solution. Increasing the sampling temperature during Vac-HSSPME reduced the extraction efficiency of smaller analytes due to the enhancement in water molecule collisions with the fiber. This effect was not recorded for the larger phenolic compounds. Based on the optimum values selected, Vac-HSSPME required a shorter extraction time and milder sampling conditions than regular HSSPME: 20 min and 35 °C for Vac-HSSPME versus 40 min and 45 °C for regular HSSPME. The performance of the optimized Vac-HSSPME and regular HSSPME procedures were assessed and Vac-HSSPME method proved to be more sensitive, with lower limits of detection (from 0.14 to 13 μg L -1 ), and better intra-day precision (relative standard deviations values < 10% at the lowest spiked level) than regular HSSPME for almost all target analytes. The proposed Vac-HSSPME method was successfully applied to quantify FFAs and phenols in milk and milk derivatives samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Multicomponent Gas Diffusion and an Appropriate Momentum Boundary Condition

NASA Technical Reports Server (NTRS)

Noever, David A.

1994-01-01

Multicomponent gas diffusion is reviewed with particular emphasis on gas flows near solid boundaries-the so-called Kramers-Kistemaker effect. The aim is to derive an appropriate momentum boundary condition which governs many gaseous species diffusing together. The many species' generalization of the traditional single gas condition, either as slip or stick (no-slip), is not obvious, particularly for technologically important cases of lower gas pressures and very dissimilar molecular weight gases. No convincing theoretical case exists for why two gases should interact with solid boundaries equally but in opposite flow directions, such that the total gas flow exactly vanishes. ln this way, the multicomponent no-slip boundary requires careful treatment The approaches discussed here generally adopt a microscopic model for gas-solid contact. The method has the advantage that the mathematics remain tractable and hence experimentally testable. Two new proposals are put forward, the first building in some molecular collision physics, the second drawing on a detailed view of surface diffusion which does not unphysically extrapolate bulk gas properties to govern the adsorbed molecules. The outcome is a better accounting of previously anomalous experiments. Models predict novel slip conditions appearing even for the case of equal molecular weight components. These approaches become particularly significant in view of a conceptual contradiction found to arise in previous derivations of the appropriate boundary conditions. The analogous case of three gases, one of which is uniformly distributed and hence non-diffusing, presents a further refinement which gives unexpected flow reversals near solid boundaries. This case is investigated alone and for aggregating gas species near their condensation point. In addition to predicting new physics, this investigation carries practical implications for controlling vapor diffusion in the growth of crystals used in medical diagnosis (e.g. mercuric iodide) and semiconductors.

Heat treatment giving a stable high temperature micro-structure in cast austenitic stainless steel

DOEpatents

Anton, Donald L.; Lemkey, Franklin D.

1988-01-01

A novel micro-structure developed in a cast austenitic stainless steel alloy and a heat treatment thereof are disclosed. The alloy is based on a multicomponent Fe-Cr-Mn-Mo-Si-Nb-C system consisting of an austenitic iron solid solution (.gamma.) matrix reinforced by finely dispersed carbide phases and a heat treatment to produce the micro-structure. The heat treatment includes a prebraze heat treatment followed by a three stage braze cycle heat treatment.

Thin Film Solid Lubricant Development

NASA Technical Reports Server (NTRS)

Benoy, Patricia A.

1997-01-01

Tribological coatings for high temperature sliding applications are addressed. A sputter-deposited bilayer coating of gold and chromium is investigated as a potential solid lubricant for protection of alumina substrates during sliding at high temperature. Evaluation of the tribological properties of alumina pins sliding against thin sputtered gold films on alumina substrates is presented.

Flowfield predictions for multiple body launch vehicles

NASA Technical Reports Server (NTRS)

Deese, Jerry E.; Pavish, D. L.; Johnson, Jerry G.; Agarwal, Ramesh K.; Soni, Bharat K.

1992-01-01

A method is developed for simulating inviscid and viscous flow around multicomponent launch vehicles. Grids are generated by the GENIE general-purpose grid-generation code, and the flow solver is a finite-volume Runge-Kutta time-stepping method. Turbulence effects are simulated using Baldwin and Lomax (1978) turbulence model. Calculations are presented for three multibody launch vehicle configurations: one with two small-diameter solid motors, one with nine small-diameter solid motors, and one with three large-diameter solid motors.

Amorphous salts formed from rapid dehydration of multicomponent chloride and ferric sulfate brines: Implications for Mars.

PubMed

Sklute, Elizabeth C; Rogers, A Deanne; Gregerson, Jason C; Jensen, Heidi B; Reeder, Richard J; Dyar, M Darby

2018-03-01

Salts with high hydration states have the potential to maintain high levels of relative humidity (RH) in the near subsurface of Mars, even at moderate temperatures. These conditions could promote deliquescence of lower hydrates of ferric sulfate, chlorides, and other salts. Previous work on deliquesced ferric sulfates has shown that when these materials undergo rapid dehydration, such as that which would occur upon exposure to present day Martian surface conditions, an amorphous phase forms. However, the fate of deliquesced halides or mixed ferric sulfate-bearing brines are presently unknown. Here we present results of rapid dehydration experiments on Ca-, Na-, Mg- and Fe-chloride brines and multi-component (Fe 2 (SO 4 ) 3 ± Ca, Na, Mg, Fe, Cl, HCO 3 ) brines at ∼21°C, and characterize the dehydration products using visible/near-infrared (VNIR) reflectance spectroscopy, mid-infrared attenuated total reflectance spectroscopy, and X-ray diffraction (XRD) analysis. We find that rapid dehydration of many multicomponent brines can form amorphous solids or solids with an amorphous component, and that the presence of other elements affects the persistence of the amorphous phase under RH fluctuations. Of the pure chloride brines, only Fe-chloride formed an amorphous solid. XRD patterns of the multicomponent amorphous salts show changes in position, shape, and magnitude of the characteristic diffuse scattering observed in all amorphous materials that could be used to help constrain the composition of the amorphous salt. Amorphous salts deliquesce at lower RH values compared to their crystalline counterparts, opening up the possibility of their role in potential deliquescence-related geologic phenomena such as recurring slope lineae (RSLs) or soil induration. This work suggests that a wide range of aqueous mixed salt solutions can lead to the formation of amorphous salts and are possible for Mars; detailed studies of the formation mechanisms, stability and transformation behaviors of amorphous salts are necessary to further constrain their contribution to Martian surface materials.

Amorphous salts formed from rapid dehydration of multicomponent chloride and ferric sulfate brines: Implications for Mars

NASA Astrophysics Data System (ADS)

Sklute, Elizabeth C.; Rogers, A. Deanne; Gregerson, Jason C.; Jensen, Heidi B.; Reeder, Richard J.; Dyar, M. Darby

2018-03-01

Salts with high hydration states have the potential to maintain high levels of relative humidity (RH) in the near subsurface of Mars, even at moderate temperatures. These conditions could promote deliquescence of lower hydrates of ferric sulfate, chlorides, and other salts. Previous work on deliquesced ferric sulfates has shown that when these materials undergo rapid dehydration, such as that which would occur upon exposure to present day Martian surface conditions, an amorphous phase forms. However, the fate of deliquesced halides or mixed ferric sulfate-bearing brines are presently unknown. Here we present results of rapid dehydration experiments on Ca-, Na-, Mg- and Fe-chloride brines and multicomponent (Fe2(SO4)3 ± Ca, Na, Mg, Fe, Cl, HCO3) brines at ∼21 °C, and characterize the dehydration products using visible/near-infrared (VNIR) reflectance spectroscopy, mid-infrared attenuated total reflectance spectroscopy, and X-ray diffraction (XRD) analysis. We find that rapid dehydration of many multicomponent brines can form amorphous solids or solids with an amorphous component, and that the presence of other elements affects the persistence of the amorphous phase under RH fluctuations. Of the pure chloride brines, only Fe-chloride formed an amorphous solid. XRD patterns of the multicomponent amorphous salts show changes in position, shape, and magnitude of the characteristic diffuse scattering observed in all amorphous materials that could be used to help constrain the composition of the amorphous salt. Amorphous salts deliquesce at lower RH values compared to their crystalline counterparts, opening up the possibility of their role in potential deliquescence-related geologic phenomena such as recurring slope lineae (RSLs) or soil induration. This work suggests that a wide range of aqueous mixed salt solutions can lead to the formation of amorphous salts and are possible for Mars; detailed studies of the formation mechanisms, stability and transformation behaviors of amorphous salts are necessary to further constrain their contribution to Martian surface materials.

Amorphous salts formed from rapid dehydration of multicomponent chloride and ferric sulfate brines: Implications for Mars

PubMed Central

Sklute, Elizabeth C.; Rogers, A. Deanne; Gregerson, Jason C.; Jensen, Heidi B.; Reeder, Richard J.; Dyar, M. Darby

2018-01-01

Salts with high hydration states have the potential to maintain high levels of relative humidity (RH) in the near subsurface of Mars, even at moderate temperatures. These conditions could promote deliquescence of lower hydrates of ferric sulfate, chlorides, and other salts. Previous work on deliquesced ferric sulfates has shown that when these materials undergo rapid dehydration, such as that which would occur upon exposure to present day Martian surface conditions, an amorphous phase forms. However, the fate of deliquesced halides or mixed ferric sulfate-bearing brines are presently unknown. Here we present results of rapid dehydration experiments on Ca–, Na–, Mg– and Fe–chloride brines and multi-component (Fe2 (SO4)3 ± Ca, Na, Mg, Fe, Cl, HCO3) brines at ∼21°C, and characterize the dehydration products using visible/near-infrared (VNIR) reflectance spectroscopy, mid-infrared attenuated total reflectance spectroscopy, and X-ray diffraction (XRD) analysis. We find that rapid dehydration of many multicomponent brines can form amorphous solids or solids with an amorphous component, and that the presence of other elements affects the persistence of the amorphous phase under RH fluctuations. Of the pure chloride brines, only Fe–chloride formed an amorphous solid. XRD patterns of the multicomponent amorphous salts show changes in position, shape, and magnitude of the characteristic diffuse scattering observed in all amorphous materials that could be used to help constrain the composition of the amorphous salt. Amorphous salts deliquesce at lower RH values compared to their crystalline counterparts, opening up the possibility of their role in potential deliquescence-related geologic phenomena such as recurring slope lineae (RSLs) or soil induration. This work suggests that a wide range of aqueous mixed salt solutions can lead to the formation of amorphous salts and are possible for Mars; detailed studies of the formation mechanisms, stability and transformation behaviors of amorphous salts are necessary to further constrain their contribution to Martian surface materials. PMID:29670302

Chromium Grain-boundary Segregation and Effect of Ion Beam Cleaning on Fe-Ni-Cr Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saraf, Laxmikant V.

2011-04-01

The grain boundaries play important role to control the mechanical strength of ternary alloys. From spacecrafts to naval vessels to nuclear reactors, stress corrosion cracking, brittleness, oxidation mostly originates at the grain boundaries and cause long term structural stability problems in most of the metallic structures [1]. Fe-Ni-Cr based ternary metal alloys have been widely studied for more than fifty years [2, 3]. Despite of vast amount of research, chromium diffusion in stainless steel or other Ni-Fe-Cr based ternary alloys is still an open scientific problem with challenges in structural stability and corrosion resistance [4]. Particularly, austenite Fe-Ni-Cr is lookedmore » upon favorably in space and jet engine industry for their improved resistance to stress corrosion cracking [5]. In solid oxide fuel cells (SOFC), Ni-alloys are frequently used as interconnects and seals [6]. In this communication, simultaneous energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) mapping is utilized to study chemical and structural aspects of chromium segregation in Fe-Ni-Cr alloy. A focused Ga-ion beam is also utilized to study the effect of ion beam cleaning on EBSD image quality (IQ) and inverse pole figure (IPF) maps of Fe-Ni-Cr alloy.« less

Welding Emissions in Shipbuilding and Repair (Briefing Charts)

DTIC Science & Technology

2009-09-03

not just about Hexavalent Chromium • http://www.weldinglawsuits.com/ 5 Naval Facilities Engineering Command/ Engineering Service Center Driving...Regulations ( the Dry Stuff) • OSHA 1910.1026 – Hexavalent Chromium Regulation • OSHA 1910.1000 – Limits for Air Contaminants – e.g. Manganese, Nickel...gas – GTAW –uses shield gas, but low emissions –aka TIG – SAW – lowest rate, solid wire weld covered with flux material 7 Naval Facilities

Maraging superalloys and heat treatment processes

DOEpatents

Korenko, Michael K.; Gelles, David S.; Thomas, Larry E.

1986-01-01

Described herein are nickel-chromium-iron maraging, gamma prime strengthened superalloys containing about 18 to 25 weight percent nickel, about 4 to 8 weight percent chromium, gamma prime forming elements such as aluminum and/or titanium, and a solid solution strengthening element, such as molybdenum. After heat treatment, which includes at least one ausaging treatment and at least one maraging treatment, a microstructure containing gamma prime phase and decomposed Fe-Ni-Cr type martensite is produced.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bradley, D. J.

The activity coefficient of carbon in nickel, nickel-titanium, nickel-titanium-chromium, nickel-titanium-molybdenum and nickel-titanium-molybdenum-chromium alloys has been measured at 900, 1100 and 1215/sup 0/C. The results indicate that carbon obeys Henry's Law over the range studied (0 to 2 at. percent). The literature for the nickel-carbon and iron-carbon systems are reviewed and corrected. For the activity of carbon in iron as a function of composition, a new relationship based on re-evaluation of the thermodynamics of the CO/CO/sub 2/ equilibrium is proposed. Calculations using this relationship reproduce the data to within 2.5 percent, but the accuracy of the calibrating standards used by manymore » investigators to analyze for carbon is at best 5 percent. This explains the lack of agreement between the many precise sets of data. The values of the activity coefficient of carbon in the various solid solutions are used to calculate a set of parameters for the Kohler-Kaufman equation. The calculations indicate that binary interaction energies are not sufficient to describe the thermodynamics of carbon in some of the nickel-based solid solutions. The results of previous workers for carbon in nickel-iron alloys are completely described by inclusion of ternary terms in the Kohler-Kaufman equation. Most of the carbon solid solution at high temperatures in nickel and nickel-titantium alloys precipitates from solution on quenching in water. The precipitate is composed of very small particles (greater than 2.5 nm) of elemental carbon. The results of some preliminary thermomigration experiments are discussed and recommendations for further work are presented.« less

Development of oxidation resistance in thoriated nickel-chromium base alloys

NASA Technical Reports Server (NTRS)

Seltzer, M. S.; Wilcox, B. A.; Jaffee, R. I.; Stringer, J.

1971-01-01

A pack process was developed which permits the introduction of nearly six weight percent aluminum into solid solution in the near-surface region of TDNiCr (Ni-20Cr-2ThO2. At this aluminum concentration an adherent alumina scale is produced on the alloy surface upon exposure to an environment of 1330 n/sq m (10 torr) or 101,000 n/sq m (760 torr) air at temperatures of 1093 C (2000 F) and 1204 C (2200 F). Room temperature mechanical properties of the aluminized alloys compare favorably with those of TDNiCr as received. While diffusivities for aluminum are a factor of three higher than those for chromium in TDNiCr or Ni-20Cr, the diffusion rates are similar for either of these elements in the thoriated or unthoriated alloy for a given temperature and grain size.

Vaporisation of candidate nuclear fuels and targets for transmutation of minor actinides

NASA Astrophysics Data System (ADS)

Gotcu-Freis, P.; Hiernaut, J.-P.; Colle, J.-Y.; Nästrén, C.; Carretero, A. Fernandez; Konings, R. J. M.

2011-04-01

The thermal stability and high temperature behaviour of candidate fuels and targets for transmutation of minor actinides has been investigated. Zirconia-based solid solution, MgO-based CERCER and molybdenum-based CERMET fuels containing Am and/or Pu in various concentrations were heated up to 2700 K in a Knudsen cell coupled with a quadrupole mass spectrometer, to measure their vapour pressure and vapour composition. The results reveal that the vaporisation of the actinides from the samples is not only determined by the thermodynamics of the system but is also related to the dynamic evolution of multi-component mixtures with complex composition or microstructure.

Femtosecond pulses generated from a synchronously pumped chromium-doped forsterite laser

NASA Technical Reports Server (NTRS)

Seas, A.; Petricevic, V.; Alfano, R. R.

1993-01-01

Kerr lens mode-locking (KLM) has become a standard method to produce femtosecond pulses from tunable solid state lasers. High power inside the laser resonator propagating through the laser-medium with nonlinear index of refraction, coupled with the stability conditions of the laser modes in the resonator, result in a passive amplitude modulation which explains the mechanism for pulse shortening. Recently, chromium doped forsterite was shown to exhibit similar pulse behavior. A successful attempt to generate femtosecond pulses from a synchronously pumped chromium-doped forsterite laser with intracavity dispersion compensation is reported. Stable, transform limited pulses with duration of 105 fs were routinely generated, tunable between 1240 to 1270 nm.

Direct Sampling and Analysis from Solid Phase Extraction Cards using an Automated Liquid Extraction Surface Analysis Nanoelectrospray Mass Spectrometry System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walworth, Matthew J; ElNaggar, Mariam S; Stankovich, Joseph J

Direct liquid extraction based surface sampling, a technique previously demonstrated with continuous flow and autonomous pipette liquid microjunction surface sampling probes, has recently been implemented as the Liquid Extraction Surface Analysis (LESA) mode on the commercially available Advion NanoMate chip-based infusion nanoelectrospray ionization system. In the present paper, the LESA mode was applied to the analysis of 96-well format custom solid phase extraction (SPE) cards, with each well consisting of either a 1 or 2 mm diameter monolithic hydrophobic stationary phase. These substrate wells were conditioned, loaded with either single or multi-component aqueous mixtures, and read out using the LESAmore » mode of a TriVersa NanoMate or a Nanomate 100 coupled to an ABI/Sciex 4000QTRAPTM hybrid triple quadrupole/linear ion trap mass spectrometer and a Thermo LTQ XL linear ion trap mass spectrometer. Extraction conditions, including extraction/nanoESI solvent composition, volume, and dwell times, were optimized in the analysis of targeted compounds. Limit of detection and quantitation as well as analysis reproducibility figures of merit were measured. Calibration data was obtained for propranolol using a deuterated internal standard which demonstrated linearity and reproducibility. A 10x increase in signal and cleanup of micromolar Angiotensin II from a concentrated salt solution was demonstrated. Additionally, a multicomponent herbicide mixture at ppb concentration levels was analyzed using MS3 spectra for compound identification in the presence of isobaric interferences.« less

Diffusion Behavior of Mn and Si Between Liquid Oxide Inclusions and Solid Iron-Based Alloy at 1473 K

NASA Astrophysics Data System (ADS)

Kim, Sun-Joong; Tago, Hanae; Kim, Kyung-Ho; Kitamura, Shin-ya; Shibata, Hiroyuki

2018-06-01

In order to clarify the changes in the composition of oxide inclusions in steel, the effect of the metal and oxide composition on the reaction between solid Fe-based alloys and liquid multi-component oxides was investigated using the diffusion couple method at 1473 K. The measured concentration gradients of Mn and Si in the metal indicated that Mn diffused into the metal from the oxide, while the diffusion of Si occurred in the opposite direction. In addition, the MnO content in the oxide decreased with heat treatment time, while the SiO2 content increased. The compositional changes in both phases indicated that the Mn content in the metal near the interface increased with heat treatment with decreasing MnO content in the oxide. Assuming local equilibrium at the interface, the calculated [Mn]2/[Si] ratio at the interface in equilibrium with the oxide increased with increases in the MnO/SiO2 ratio in the oxide. The difference in the [Mn]2/[Si] ratios between the interface and the metal matrix increased, which caused the diffusion of Mn and Si between the multi-component oxide and metal. By measuring the diffusion lengths of Mn and Si in the metal, the chemical diffusion coefficients of Mn and Si were obtained to calculate the composition changes in Mn and Si in the metal. The calculated changes in Mn and Si in the metal agreed with the experimental results.

The effect of moisture on the release and enrichment of heavy metals during pyrolysis of municipal solid waste.

PubMed

Raclavská, Helena; Corsaro, Agnieszka; Hlavsová, Adéla; Juchelková, Dagmar; Zajonc, Ondřej

2015-03-01

The investigation of the effect of moisture on the release and enrichment of heavy metals during pyrolysis of municipal solid waste is essential. This is important owing to: (i) the increasing amount of metals in the solid product of pyrolysis beyond the normalised level; (ii) the effect of moisture on the overall cost of pyrolysis process; and (iii) the utilisation of pyrolysis products. Seven metals were selected for evaluation: arsenic, cadmium, chromium, mercury, nickel, lead, and vanadium. Pyrolysis experiments were conducted in a steel retort at 650 °C. The municipal solid waste samples with moisture contents of 0, 30, and 65 wt% were investigated. The relative enrichment index and release of heavy metals were evaluated individually for liquid and solid fractions. A consistent trend was observed for the majority of metals investigated. Reductions of relative enrichment index and release, i.e. an increase of volatility, were observed for arsenic, chromium, cadmium, nickel, and vanadium, with an increase of municipal solid waste moisture. Whereas divergent results were obtained for lead and mercury. The effect of moisture on the relative enrichment index and release was greater at 65 wt% moisture than at 30 wt% for lead, and more remarkable at 30 wt% than at 65 wt% for mercury. © The Author(s) 2015.

Cracking Tendancies of Restrained Welds in High Strength Low Alloy Steels under Hyperbaric Conditions.

DTIC Science & Technology

1987-06-01

refinement of NICUAGE by addition of Chromium and Molybdenum with prescribed heat ’I. 24 [I.% treatments to even further lower the DBTT to -115 degrees F...sulpher a., reduces hi temp transformation products " provides solid solution strengthening copper - precipitation strengthening O chromium - optimize...contractors and oil companies include GTAW , GMAW, FCAW, and SMAW. My sense was -, that the most popular technique was the GTAW root pass * followed by the

Multicomponent chemical imaging of pharmaceutical solid dosage forms with broadband CARS microscopy.

PubMed

Hartshorn, Christopher M; Lee, Young Jong; Camp, Charles H; Liu, Zhen; Heddleston, John; Canfield, Nicole; Rhodes, Timothy A; Hight Walker, Angela R; Marsac, Patrick J; Cicerone, Marcus T

2013-09-03

We compare a coherent Raman imaging modality, broadband coherent anti-Stokes Raman scattering (BCARS) microscopy, with spontaneous Raman microscopy for quantitative and qualitative assessment of multicomponent pharmaceuticals. Indomethacin was used as a model active pharmaceutical ingredient (API) and was analyzed in a tabulated solid dosage form, embedded within commonly used excipients. In comparison with wide-field spontaneous Raman chemical imaging, BCARS acquired images 10× faster, at higher spatiochemical resolution and with spectra of much higher SNR, eliminating the need for multivariate methods to identify chemical components. The significant increase in spatiochemical resolution allowed identification of an unanticipated API phase that was missed by the spontaneous wide-field method and bulk Raman spectroscopy. We confirmed the presence of the unanticipated API phase using confocal spontaneous Raman, which provided spatiochemical resolution similar to BCARS but at 100× slower acquisition times.

Electroepitaxy of multicomponent systems - Ternary and quarternary compounds

NASA Technical Reports Server (NTRS)

Bryskiewicz, T.; Lagowski, J.; Gatos, H. C.

1980-01-01

A theoretical model is presented which accounts for the electroepitaxial growth kinetics and composition of multicomponent compounds in terms of mass transport in the liquid and phase diagram relationships. The mass transport in the interface is dominated by electromigration in the absence of convection and by diffusion in the presence of convection. The composition of the solid is controlled by the Peltier effect at the growth interface and by the diffusion and mobility constants of the solute components and the growth velocity (current density). Thus, for a given solution composition, the composition of the solid can be varied by varying the current density. For a given current density the composition remains constant even in the case of relatively thick epitaxial layers. All aspects of the model were found to be in good agreement with the growth and composition characteristics of Ga/x-1/Al/x/As layers.

Synthesis and structure characterization of chromium oxide prepared by solid thermal decomposition reaction.

PubMed

Li, Li; Yan, Zi F; Lu, Gao Q; Zhu, Zhong H

2006-01-12

Mesoporous chromium oxide (Cr2O3) nanocrystals were first synthesized by the thermal decomposition reaction of Cr(NO3)3.9H2O using citric acid monohydrate (CA) as the mesoporous template agent. The texture and chemistry of chromium oxide nanocrystals were characterized by N2 adsorption-desorption isotherms, FTIR, X-ray diffraction (XRD), UV-vis, and thermoanalytical methods. It was shown that the hydrate water and CA are the crucial factors in influencing the formation of mesoporous Cr2O3 nanocrystals in the mixture system. The decomposition of CA results in the formation of a mesoporous structure with wormlike pores. The hydrate water of the mixture provides surface hydroxyls that act as binders, making the nanocrystals aggregate. The pore structures and phases of chromium oxide are affected by the ratio of precursor-to-CA, thermal temperature, and time.

Machine learning assisted first-principles calculation of multicomponent solid solutions: estimation of interface energy in Ni-based superalloys

NASA Astrophysics Data System (ADS)

Chandran, Mahesh; Lee, S. C.; Shim, Jae-Hyeok

2018-02-01

A disordered configuration of atoms in a multicomponent solid solution presents a computational challenge for first-principles calculations using density functional theory (DFT). The challenge is in identifying the few probable (low energy) configurations from a large configurational space before DFT calculation can be performed. The search for these probable configurations is possible if the configurational energy E({\\boldsymbol{σ }}) can be calculated accurately and rapidly (with a negligibly small computational cost). In this paper, we demonstrate such a possibility by constructing a machine learning (ML) model for E({\\boldsymbol{σ }}) trained with DFT-calculated energies. The feature vector for the ML model is formed by concatenating histograms of pair and triplet (only equilateral triangle) correlation functions, {g}(2)(r) and {g}(3)(r,r,r), respectively. These functions are a quantitative ‘fingerprint’ of the spatial arrangement of atoms, familiar in the field of amorphous materials and liquids. The ML model is used to generate an accurate distribution P(E({\\boldsymbol{σ }})) by rapidly spanning a large number of configurations. The P(E) contains full configurational information of the solid solution and can be selectively sampled to choose a few configurations for targeted DFT calculations. This new framework is employed to estimate (100) interface energy ({σ }{{IE}}) between γ and γ \\prime at 700 °C in Alloy 617, a Ni-based superalloy, with composition reduced to five components. The estimated {σ }{{IE}} ≈ 25.95 mJ m-2 is in good agreement with the value inferred by the precipitation model fit to experimental data. The proposed new ML-based ab initio framework can be applied to calculate the parameters and properties of alloys with any number of components, thus widening the reach of first-principles calculation to realistic compositions of industrially relevant materials and alloys.

Some aspects of analytical chemistry as applied to water quality assurance techniques for reclaimed water: The potential use of X-ray fluorescence spectrometry for automated on-line fast real-time simultaneous multi-component analysis of inorganic pollutants in reclaimed water

NASA Technical Reports Server (NTRS)

Ling, A. C.; Macpherson, L. H.; Rey, M.

1981-01-01

The potential use of isotopically excited energy dispersive X-ray fluorescence (XRF) spectrometry for automated on line fast real time (5 to 15 minutes) simultaneous multicomponent (up to 20) trace (1 to 10 parts per billion) analysis of inorganic pollutants in reclaimed water was examined. Three anionic elements (chromium 6, arsenic and selenium) were studied. The inherent lack of sensitivity of XRF spectrometry for these elements mandates use of a preconcentration technique and various methods were examined, including: several direct and indirect evaporation methods; ion exchange membranes; selective and nonselective precipitation; and complexation processes. It is shown tha XRF spectrometry itself is well suited for automated on line quality assurance, and can provide a nondestructive (and thus sample storage and repeat analysis capabilities) and particularly convenient analytical method. Further, the use of an isotopically excited energy dispersive unit (50 mCi Cd-109 source) coupled with a suitable preconcentration process can provide sufficient sensitivity to achieve the current mandated minimum levels of detection without the need for high power X-ray generating tubes.

Wear Behavior of Low-Cost, Lightweight TiC/Ti-6Al-4V Composite Under Fretting: Effectiveness of Solid-Film Lubricant Counterparts

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa; Street, Kenneth W., Jr.; Sanders, Jeffrey H.; Hager, Carl H., Jr.; Zabinski, Jeffrey S.; VanderWal, Randall L.; Andrews, Rodney; Lerch, Bradley A.

2007-01-01

The wear behavior of low-cost, lightweight 10-wt% TiC-particulate-reinforced Ti-6Al-4V matrix composite (TiC/Ti- 6Al-4V) was examined under fretting at 296, 423, and 523 K in air. Bare 10-wt% TiC/Ti-6Al-4V hemispherical pins were used in contact with dispersed multiwalled carbon nanotubes (MWNTs), magnetron-sputtered diamondlike carbon/chromium (DLC/Cr), magnetron-sputtered graphite-like carbon/chromium (GLC/Cr), and magnetron-sputtered molybdenum disulphide/titanium (MoS2/Ti) deposited on Ti-6Al-4V, Ti-48Al-2Cr-2Nb, and nickel-based superalloy 718. When TiC/Ti-6Al-4V was brought into contact with bare Ti-6Al-4V, bare Ti-48Al-2Cr-2Nb, and bare nickel-based superalloy 718, strong adhesion, severe galling, and severe wear occurred. However, when TiC/Ti-6Al-4V was brought into contact with MWNT, DLC/Cr, GLC/Cr, and MoS2/Ti coatings, no galling occurred in the contact, and relatively minor wear was observed regardless of the coating. All the solid-film lubricants were effective from 296 to 523 K, but the effectiveness of the MWNT, DLC/Cr, GLC/Cr, and MoS2/Ti coatings decreased as temperature increased.

FOURTH ANNUAL REPORT ON DISTRIBUTION STUDIES BETWEEN MELTS AND SOLID PHASES USING RADIOACTIVE TRACERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, R.; Orr, W.C.; Katz, L.

Cerium(III) ion in a barium chloride flux does not readily exchangs with any of the ions in solid BaZrO/sub 3/ or BaTiO/sub 3/. It reacts to form new solid phases, which are identified, and does not enter the original crystal lattices at an appreciable rate. The strontium was found to exchange at a measurable rate with barium in BaTiO/sub 3/ and with the corresponding ions in alkaline-earth zirconates. Results of a series of equilibrium and rate measurements were interpreted to ahow that the exchange produces an additional solid phase, SrTiO/sub 3/, rather than the mixed phase, or solid solution, thatmore » ndght have been expected. The significance of this observation is discussed. The self-exchange of yttnium ions between a solid compound of yttrium and an alkali chloride flux in which yttrium chloride is dissolved appears in the systems studied to depend primaaily on the solubility of the solid. Exchange is rapid and complete in the case of yttrium oxychlonide, which is soluble to the extent of 0.6%, but is limited to the surface of yttrium chromium oxide, which has no measurable solubility in the flux. The introduction of yttrium ion vacancies in the lattice of yttrium chromium oxide has no detectable effect in promoting exchange. (For preceding period see NYO-3279.) (auth)« less

Chromium Ions in Tetrahedral Sites

DTIC Science & Technology

1991-09-01

octahedral sites-the inversion site and the mirror site.4 After energy level calculations were performed, it was found that chromium ions in octahedral sites...octahedral site with symmetry C, the other half at the mirror octahedral sites with symmetry Cs. Its structure projected on (100) plane is shown in Fig... mirror symmetry. I 181 !U 10O 0 0 Fig. 2.1 Unit cell of forsterite, Mg2SiO4. Small open and solid circles are Mg atoms, big circles are 0 atoms and

Modified Ion-Conducting Ceramics Based on Lanthanum Gallate: Synthesis, Structure, and Properties

NASA Astrophysics Data System (ADS)

Kaleva, G. M.; Politova, E. D.; Mosunov, A. V.; Sadovskaya, N. V.

2018-06-01

A review is presented of the synthesis and complex investigation of modified ion-conducting ceramics based on heterosubstituted lanthanum gallate as a promising electrolyte material for solid oxide fuel cells. The effect the composition of multicomponent complex oxides has on the structure, microstructure, and electrophysical properties of ceramics is examined. Samples of ceramics with new compositions are produced via solid-state synthesis and modified with lithium fluoride. A drop is observed in the sintering temperature of the ceramics, caused by the liquid phase mechanism of sintering as a result of the low-melting superstoichiometric quantities of the additive. The effect lithium fluoride has on the process of phase formation, microstructure, and conductivity of the ceramics is investigated. It is found that samples modified with lithium fluoride display high density, dense grain packing, and high values of electrical conductivity at high temperatures.

Local electronic effects and irradiation resistance in high-entropy alloys

DOE PAGES

Egami, Takeshi; Stocks, George Malcolm; Nicholson, Don; ...

2015-08-14

High-entropy alloys are multicomponent solid solutions in which various elements with different chemistries and sizes occupy the same crystallographic lattice sites. Thus, none of the atoms perfectly fit the lattice site, giving rise to considerable local lattice distortions and atomic-level stresses. These characteristics can be beneficial for performance under both radiation and in a high-temperature environment, making them attractive candidates as nuclear materials. We discuss electronic origin of the atomic-level stresses based upon first-principles calculations using a density functional theory approach.

40 CFR 63.702 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... tape manufacturing are: y-oxide, doped iron oxides, chromium dioxide, barium ferrite, and metallic... uncombined water, that exists as liquid or solid particles such as dust, smoke, mist, or fumes at standard...

40 CFR 63.702 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... tape manufacturing are: y-oxide, doped iron oxides, chromium dioxide, barium ferrite, and metallic... uncombined water, that exists as liquid or solid particles such as dust, smoke, mist, or fumes at standard...

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

PubMed

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

2016-10-01

In this study bacterial cellulose-magnetite composites were synthesised for the removal of chromium(VI) from aqueous solutions. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis and X-ray Photoelectron Spectroscopy (XPS) were used to characterize the bacterial cellulose-magnetite composites and to reveal the uniform dispersion of nanomagnetite in the BC matrix. Magnetic properties were also measured to confirm the magnetite immobilization on bacterial cellulose membrane. The effects of initial Cr(VI) concentration, solution pH and solid/liquid ratio upon chromium removal were examined using the statistical Box-Behnken Design. Because of the possibility of magnetite dissolution during chromium(VI) adsorption, the degree of iron leaching was also analysed in the same conditions as Cr(VI) adsorption. From the factors affecting chromium(VI) adsorption the most important was solution pH. The highest Cr(VI) removal efficiency was observed at pH 4, accompanied by the lowest iron leaching in the solution. The adsorption experiments also indicated that the adsorption process of chromium(VI) is well described by Freundlich adsorption model. Our results proved that the BC-magnetite composites could be used for an efficient removal of chromium(VI) from diluted solutions with a minimum magnetite dissolution during operation. Copyright © 2016 Elsevier B.V. All rights reserved.

Site-specific transition metal occupation in multicomponent pyrophosphate for improved electrochemical and thermal properties in lithium battery cathodes: a combined experimental and theoretical study.

PubMed

Shakoor, Rana A; Kim, Heejin; Cho, Woosuk; Lim, Soo Yeon; Song, Hannah; Lee, Jung Woo; Kang, Jeung Ku; Kim, Yong-Tae; Jung, Yousung; Choi, Jang Wook

2012-07-18

As an attempt to develop lithium ion batteries with excellent performance, which is desirable for a variety of applications including mobile electronics, electrical vehicles, and utility grids, the battery community has continuously pursued cathode materials that function at higher potentials with efficient kinetics for lithium insertion and extraction. By employing both experimental and theoretical tools, herein we report multicomponent pyrophosphate (Li(2)MP(2)O(7), M = Fe(1/3)Mn(1/3)Co(1/3)) cathode materials with novel and advantageous properties as compared to the single-component analogues and other multicomponent polyanions. Li(2)Fe(1/3)Mn(1/3)Co(1/3)P(2)O(7) is formed on the basis of a solid solution among the three individual transition-metal-based pyrophosphates. The unique crystal structure of pyrophosphate and the first principles calculations show that different transition metals have a tendency to preferentially occupy either octahedral or pyramidal sites, and this site-specific transition metal occupation leads to significant improvements in various battery properties: a single-phase mode for Li insertion/extraction, improved cell potentials for Fe(2+)/Fe(3+) (raised by 0.18 eV) and Co(2+)/Co(3+) (lowered by 0.26 eV), and increased activity for Mn(2+)/Mn(3+) with significantly reduced overpotential. We reveal that the favorable energy of transition metal mixing and the sequential redox reaction for each TM element with a sufficient redox gap is the underlying physical reason for the preferential single-phase mode of Li intercalation/deintercalation reaction in pyrophosphate, a general concept that can be applied to other multicomponent systems. Furthermore, an extremely small volume change of ~0.7% between the fully charged and discharged states and the significantly enhanced thermal stability are observed for the present material, the effects unseen in previous multicomponent battery materials.

Predicting Microstructure and Microsegregation in Multicomponent Aluminum Alloys

NASA Astrophysics Data System (ADS)

Yan, Xinyan; Ding, Ling; Chen, ShuangLin; Xie, Fanyou; Chu, M.; Chang, Y. Austin

Accurate predictions of microstructure and microsegregation in metallic alloys are highly important for applications such as alloy design and process optimization. Restricted assumptions concerning the phase diagram could easily lead to erroneous predictions. The best approach is to couple microsegregation modeling with phase diagram computations. A newly developed numerical model for the prediction of microstructure and microsegregation in multicomponent alloys during dendritic solidification was introduced. The micromodel is directly coupled with phase diagram calculations using a user-friendly and robust phase diagram calculation engine-PANDAT. Solid state back diffusion, undercooling and coarsening effects are included in this model, and the experimentally measured cooling curves are used as the inputs to carry out the calculations. This model has been used to predict the microstructure and microsegregation in two multicomponent aluminum alloys, 2219 and 7050. The calculated values were confirmed using results obtained from directional solidification.

The reactivity of Fe(II) associated with goethite formed during short redox cycles toward Cr(VI) reduction under oxic conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tomaszewski, Elizabeth J.; Lee, Seungyeol; Rudolph, Jared

Chromium (Cr) is a toxic metal that causes a myriad of health problems and enters the environment as a result of anthropogenic activities and/or natural processes. The toxicity and solubility of chromium is linked to its oxidation state; Cr(III) is poorly soluble and relatively nontoxic, while Cr(VI) is soluble and a known carcinogen. Solid Fe(II) in iron-bearing minerals, such as pyrite, magnetite, and green rusts, reduce the oxidation state of chromium, reducing its toxicity and mobility. However, these minerals are not the only potential sources of solid-associated Fe(II) available for Cr(VI) reduction. For example, ferric (Fe(III)) (hydr)oxides, such as goethitemore » or hematite, can have Fe(II) in the solid without phase transformation; however, the reactivity of Fe(II) within Fe(III) (hydr)oxides with contaminants, has not been previously investigated. Here, we cyclically react goethite with dissolved Fe(II) followed by dissolved O2, leading to the formation of reactive Fe(II) associated with goethite. In separate reactors, the reactivity of this Fe(II) is probed under oxic conditions, by exposure to chromate (CrO42 -) after either one, two, three or four redox cycles. Cr is not present during redox cycling; rather, it is introduced to a subset of the solid after each oxidation half-cycle. Analysis of X-ray absorption near edge structure (XANES) spectra reveals that the extent of Cr(VI) reduction to Cr(III) depends not only on solid Fe(II) content but also surface area and mean size of ordered crystalline domains, determined by BET surface area analysis and X-ray diffraction (XRD), respectively. Shell-by-shell fitting of the extended X-ray absorption fine structure (EXAFS) spectra demonstrates chromium forms both single and double corner sharing complexes on the surface of goethite, in addition to sorbed Cr(III) species. Finally, transmission electron microscope (TEM) imaging and X-ray energy-dispersive spectroscopy (EDS) illustrate that Cr preferentially localizes on the (100) face of goethite, independent of the number of redox cycles goethite undergoes. This work demonstrates that under oxic conditions, solid Fe(II) associated with goethite resulting from rapid redox cycling is reactive and available for electron transfer to Cr(VI), suggesting Fe(III) (hydr)oxides may act as reservoirs of reactive electron density, even in oxygen saturated environments.« less

Regeneration of pilot-scale ion exchange columns for hexavalent chromium removal.

PubMed

Korak, Julie A; Huggins, Richard; Arias-Paic, Miguel

2017-07-01

Due to stricter regulations, some drinking water utilities must implement additional treatment processes to meet potable water standards for hexavalent chromium (Cr(VI)), such as the California limit of 10 μg/L. Strong base anion exchange is effective for Cr(VI) removal, but efficient resin regeneration and waste minimization are important for operational, economic and environmental considerations. This study compared multiple regeneration methods on pilot-scale columns on the basis of regeneration efficiency, waste production and salt usage. A conventional 1-Stage regeneration using 2 N sodium chloride (NaCl) was compared to 1) a 2-Stage process with 0.2 N NaCl followed by 2 N NaCl and 2) a mixed regenerant solution with 2 N NaCl and 0.2 N sodium bicarbonate. All methods eluted similar cumulative amounts of chromium with 2 N NaCl. The 2-Stage process eluted an additional 20-30% of chromium in the 0.2 N fraction, but total resin capacity is unaffected if this fraction is recycled to the ion exchange headworks. The 2-Stage approach selectively eluted bicarbonate and sulfate with 0.2 N NaCl before regeneration using 2 N NaCl. Regeneration approach impacted the elution efficiency of both uranium and vanadium. Regeneration without co-eluting sulfate and bicarbonate led to incomplete uranium elution and potential formation of insoluble uranium hydroxides that could lead to long-term resin fouling, decreased capacity and render the resin a low-level radioactive solid waste. Partial vanadium elution occurred during regeneration due to co-eluting sulfate suppressing vanadium release. Waste production and salt usage were comparable for the 1- and 2-Stage regeneration processes with similar operational setpoints with respect to chromium or nitrate elution. Published by Elsevier Ltd.

Mechanical, Corrosion, and Fatigue Properties of 15-5 PH, Inconel 718, and Rene 41 Weldments

DTIC Science & Technology

1975-05-01

TUCUMvARI (PGH 2) It was originally developed for high - temperature use by Armco Steel Corporation. 2 High strength is obtained by the precipitation...Rene 41 was developed by General Electric Company as a high - temperature turbine alloy. It is a nickel-base alloy, high in chromium, cobalt, and... molybdenum . Its high strength comes from the precipitation of a gamma-prime phase consisting of Ni3AI and Ni5Ti, and from the solid solution effects of

Process for the production of star-tracking reticles

NASA Technical Reports Server (NTRS)

Toft, A. R.; Smith, W. O.

1974-01-01

Reticles designed with quartz bases are masked with desired pattern and then are coated with highly adherent layers of chromium, chromium silver alloy, silver, copper, and black chromium (mixture of chromium and chromium oxides). Black chromium final layer produces required nonreflective surface.

Background Paper on Aerospace & Missile Needs

DTIC Science & Technology

2006-05-01

Micro- welding based coatings Trivalent chromium plated coatings Nano-composite Ni-P and Co-P based plated coatings Thermal diffusion coatings Plasma...working in conjunction with Advanced Surfaces and Processes, Inc. to determine the applicability of another type of ESD process. Trivalent Chromium ...Plating: Trivalent chromium is considered to be much less toxic than hexavalent chromium . Consequently, trivalent chromium coatings are being

Hard Chrome-Coated and Fullerene-Doped Metal Surfaces in Orthopedic Bearings.

PubMed

Sonntag, Robert; Feige, Katja; Dos Santos, Claudia Beatriz; Kretzer, Jan Philippe

2017-12-20

Metal-on-metal bearings for total hip replacements have been introduced as an alternative to polyethylene in young and more active patients. These have, however, been shown to be prone to implant malpositioning and have been limited by some specific design features. In that context, coatings present an option to increase wear resistance by keeping the high fracture strength of the metal substrate. A custom-made electroplating setup was designed for the coating of CoCr substrates using (a) an industrial standard chromium electrolyte; (b) a custom-made hexavalent chromium (Cr 6+ ) electrolyte with a reduced chromium trioxide (CrO₃) content, both without solid additives and (c) with the addition of fullerene (C 60 ) nanoparticles; and (d) a trivalent chromium (Cr 3+ ) electrolyte with C 60 addition. All coatings showed an increase in microhardness compared with the metal substrate. Trivalent coatings were thinner (10 µm) than the hexavalent coatings (23-40 µm) and resulted in increased roughness and crack density. Wear was found to be reduced for the hexavalent chromium coatings by 70-84% compared with the CoCr-CoCr reference bearing while the trivalent chromium coating even increased wear by more than 300%. The addition of fullerenes to the electrolyte did not show any further tribological effect.

Hard Chrome-Coated and Fullerene-Doped Metal Surfaces in Orthopedic Bearings

PubMed Central

Feige, Katja; dos Santos, Claudia Beatriz; Kretzer, Jan Philippe

2017-01-01

Metal-on-metal bearings for total hip replacements have been introduced as an alternative to polyethylene in young and more active patients. These have, however, been shown to be prone to implant malpositioning and have been limited by some specific design features. In that context, coatings present an option to increase wear resistance by keeping the high fracture strength of the metal substrate. A custom-made electroplating setup was designed for the coating of CoCr substrates using (a) an industrial standard chromium electrolyte; (b) a custom-made hexavalent chromium (Cr6+) electrolyte with a reduced chromium trioxide (CrO3) content, both without solid additives and (c) with the addition of fullerene (C60) nanoparticles; and (d) a trivalent chromium (Cr3+) electrolyte with C60 addition. All coatings showed an increase in microhardness compared with the metal substrate. Trivalent coatings were thinner (10 µm) than the hexavalent coatings (23–40 µm) and resulted in increased roughness and crack density. Wear was found to be reduced for the hexavalent chromium coatings by 70–84% compared with the CoCr–CoCr reference bearing while the trivalent chromium coating even increased wear by more than 300%. The addition of fullerenes to the electrolyte did not show any further tribological effect. PMID:29261128

Diffusion in thoriated and nonthoriated nickel and nickel-chromium alloys at 1260 C

NASA Technical Reports Server (NTRS)

Whittenberger, J. D.

1972-01-01

Various solid-solid diffusion couples were assembled from thoriated and nonthoriated nickel-base alloys, welded, and diffusion annealed at 1260 C. Concentration profiles indicated that a thoria dispersion does not affect diffusion in Cr(alloy):Ni and Ni-4.8Al:Ni types of couples unless a fine grain structure is retained by the thoria particles. Metallography revealed the presence of thoria-free bands in the thoriated-Ni side of the diffusion zone. The bands contained grain boundaries and, in some cases, non-Kirkendall porosity. A mechanism based on the operation of vacancy sources is proposed to explain the thoria-free bands. In addition, a particular DS-NiCr:Ni couple had negligible Kirkendall porosity. This behavior was related to the grain structure of the particular lot of DS-NiCr.

Elemental speciation for chromium in chromium picolinate products

NASA Astrophysics Data System (ADS)

Ding, Hong; Olson, Lisa K.; Caruso, Joseph A.

1996-12-01

Chromium picolinate products have been examined for different forms of chromium, using chromatographic separation and inductively coupled plasma mass spectrometric detection. The brands we evaluated contained no detectable amount of elemental chromium(VI), the toxic form. Since chromium picolinate might have other chromium forms as impurities, different products may contain different forms of chromium species. Compared with ion-exchange, reversed-phase chromatography showed excellent chromium recovery based on the amount stated on the product label.

High Power Diode Laser-Treated HP-HVOF and Twin Wire Arc-Sprayed Coatings for Fossil Fuel Power Plants

NASA Astrophysics Data System (ADS)

Mann, B. S.

2013-08-01

This article deals with high power diode laser (HPDL) surface modification of twin wire arc-sprayed (TWAS) and high pressure high velocity oxy-fuel (HP-HVOF) coatings to combat solid particle erosion occurring in fossil fuel power plants. To overcome solid particle impact wear above 673 K, Cr3C2-NiCr-, Cr3C2-CoNiCrAlY-, and WC-CrC-Ni-based HVOF coatings are used. WC-CoCr-based HVOF coatings are generally used below 673 K. Twin wire arc (TWA) spraying of Tafa 140 MXC and SHS 7170 cored wires is used for a wide range of applications for a temperature up to 1073 K. Laser surface modification of high chromium stainless steels for steam valve components and LPST blades is carried out regularly. TWA spraying using SHS 7170 cored wire, HP-HVOF coating using WC-CoCr powder, Ti6Al4V alloy, and high chromium stainless steels (X20Cr13, AISI 410, X10CrNiMoV1222, 13Cr4Ni, 17Cr4Ni) were selected in the present study. Using robotically controlled parameters, HPDL surface treatments of TWAS-coated high strength X10CrNiMoV1222 stainless steel and HP-HVOF-coated AISI 410 stainless steel samples were carried out and these were compared with HPDL-treated high chromium stainless steels and titanium alloy for high energy particle impact wear (HEPIW) resistance. The HPDL surface treatment of the coatings has improved the HEPIW resistance manifold. The improvement in HPDL-treated stainless steels and titanium alloys is marginal and it is not comparable with that of HPDL-treated coatings. These coatings were also compared with "as-sprayed" coatings for fracture toughness, microhardness, microstructure, and phase analyses. The HEPIW resistance has a strong relationship with the product of fracture toughness and microhardness of the HPDL-treated HP-HVOF and TWAS SHS 7170 coatings. This development opens up a possibility of using HPDL surface treatments in specialized areas where the problem of HEPIW is very severe. The HEPIW resistance of HPDL-treated high chromium stainless steels and titanium alloys, HPDL-treated TWAS SHS 7170 and HP-HVOF coatings, and their micrographs and X-ray diffraction analysis is reported in this article.

40 CFR 302.6 - Notification requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... RQ of solid particles of antimony, arsenic, beryllium, cadmium, chromium, copper, lead, nickel.... 14, 1989; 63 FR 13475, Mar. 19, 1998; 63 FR 42189, Aug. 6, 1998; 64 FR 13114, Mar. 17, 1999; 65 FR...

40 CFR 302.6 - Notification requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... RQ of solid particles of antimony, arsenic, beryllium, cadmium, chromium, copper, lead, nickel.... 14, 1989; 63 FR 13475, Mar. 19, 1998; 63 FR 42189, Aug. 6, 1998; 64 FR 13114, Mar. 17, 1999; 65 FR...

40 CFR 302.6 - Notification requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... RQ of solid particles of antimony, arsenic, beryllium, cadmium, chromium, copper, lead, nickel.... 14, 1989; 63 FR 13475, Mar. 19, 1998; 63 FR 42189, Aug. 6, 1998; 64 FR 13114, Mar. 17, 1999; 65 FR...

SORPTION OF TOXIC ORGANIC COMPOUNDS ON WATERWATER SOLIDS: MECHANISMS AND MODELING

EPA Science Inventory

It is proposed that sorption is a combination of two fundamentally different processes: adsorption and partitioning. A sorption model was developed for both single-component and multicomponent systems. The model was tested using single-component experimental isotherm data of eig...

Energy dissipation in Ni-containing concentrated solid solutions.

NASA Astrophysics Data System (ADS)

Samolyuk, German; Mu, Sai; Jin, Ke; Bei, Hongbin; Stocks, G. Malcolm

Due to high disorder the diffusion processes are noticeably suppressed concentrated solid solution, so called high entropy alloys. It makes these alloys promising candidate for energy application under extreme conditions. Understanding of the energy dissipation in these alloys during the irradiation or interaction with laser bean is extremely important. In the metals and alloys the main channel of energy dissipation is provided by the electronic subsystem. The first principles approach was used to investigate the electronic structure properties of the alloys. The obtained results were used to calculate the electronic part of thermal resistivity caused by scattering of electrons on atomic disorder, magnetic and phonon excitations The contribution of last two excitations to the temperature dependence of thermal resistivity is discussed. The importance of magnetism in 3d transition metals based alloy was demonstrated. In particular, it was shown that antiferromagnetic ordering of chromium or manganese leads to significant increase of electron scattering in alloy containing these elements. It results in significant reduction of conductivity in chromium or manganese containing alloys. The comparison with the existing experimental data is discussed. This work was supported as part of the Energy Dissipation to Defect Evolution (EDDE), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences.

High performance superconducting devices enabled by three dimensionally ordered nanodots and/or nanorods

DOEpatents

Goyal, Amit

2013-09-17

Novel articles and methods to fabricate same with self-assembled nanodots and/or nanorods of a single or multicomponent material within another single or multicomponent material for use in electrical, electronic, magnetic, electromagnetic and electrooptical devices is disclosed. Self-assembled nanodots and/or nanorods are ordered arrays wherein ordering occurs due to strain minimization during growth of the materials. A simple method to accomplish this when depositing in-situ films is also disclosed. Device applications of resulting materials are in areas of superconductivity, photovoltaics, ferroelectrics, magnetoresistance, high density storage, solid state lighting, non-volatile memory, photoluminescence, thermoelectrics and in quantum dot lasers.

High performance electrical, magnetic, electromagnetic and electrooptical devices enabled by three dimensionally ordered nanodots and nanorods

DOEpatents

Goyal, Amit , Kang; Sukill, [Knoxville, TN

2012-02-21

Novel articles and methods to fabricate same with self-assembled nanodots and/or nanorods of a single or multicomponent material within another single or multicomponent material for use in electrical, electronic, magnetic, electromagnetic and electrooptical devices is disclosed. Self-assembled nanodots and/or nanorods are ordered arrays wherein ordering occurs due to strain minimization during growth of the materials. A simple method to accomplish this when depositing in-situ films is also disclosed. Device applications of resulting materials are in areas of superconductivity, photovoltaics, ferroelectrics, magnetoresistance, high density storage, solid state lighting, non-volatile memory, photoluminescence, thermoelectrics and in quantum dot lasers.

High performance devices enabled by epitaxial, preferentially oriented, nanodots and/or nanorods

DOEpatents

Goyal, Amit [Knoxville, TN

2011-10-11

Novel articles and methods to fabricate same with self-assembled nanodots and/or nanorods of a single or multicomponent material within another single or multicomponent material for use in electrical, electronic, magnetic, electromagnetic, superconducting and electrooptical devices is disclosed. Self-assembled nanodots and/or nanorods are ordered arrays wherein ordering occurs due to strain minimization during growth of the materials. A simple method to accomplish this when depositing in-situ films is also disclosed. Device applications of resulting materials are in areas of superconductivity, photovoltaics, ferroelectrics, magnetoresistance, high density storage, solid state lighting, non-volatile memory, photoluminescence, thermoelectrics and in quantum dot lasers.

Effects of land use on water quality and transport of selected constituents in streams in Mecklenburg County, North Carolina, 1994–98

USGS Publications Warehouse

Ferrell, Gloria M.

2001-01-01

Transport rates for total solids, total nitrogen, total phosphorus, biochemical oxygen demand, chromium, copper, lead, nickel, and zinc during 1994–98 were computed for six stormwater-monitoring sites in Mecklenburg County, North Carolina. These six stormwater-monitoring sites were operated by the Mecklenburg County Department of Environmental Protection, in cooperation with the City of Charlotte, and are located near the mouths of major streams. Constituent transport at the six study sites generally was dominated by nonpoint sources, except for nitrogen and phosphorus at two sites located downstream from the outfalls of major municipal wastewater-treatment plants.To relate land use to constituent transport, regression equations to predict constituent yield were developed by using water-quality data from a previous study of nine stormwater-monitoring sites on small streams in Mecklenburg County. The drainage basins of these nine stormwater sites have relatively homogeneous land-use characteristics compared to the six study sites. Mean annual construction activity, based on building permit files, was estimated for all stormwater-monitoring sites and included as an explanatory variable in the regression equations. These regression equations were used to predict constituent yield for the six study sites. Predicted yields generally were in agreement with computed yields. In addition, yields were predicted by using regression equations derived from a national urban water-quality database. Yields predicted from the regional regression equations generally were about an order of magnitude lower than computed yields.Regression analysis indicated that construction activity was a major contributor to transport of the constituents evaluated in this study except for total nitrogen and biochemical oxygen demand. Transport of total nitrogen and biochemical oxygen demand was dominated by point-source contributions. The two study basins that had the largest amounts of construction activity also had the highest total solids yields (1,300 and 1,500 tons per square mile per year). The highest total phosphorus yields (3.2 and 1.7 tons per square mile per year) attributable to nonpoint sources also occurred in these basins. Concentrations of chromium, copper, lead, nickel, and zinc were positively correlated with total solids concentrations at most of the study sites (Pearson product-moment correlation >0.50). The site having the highest median concentrations of chromium, copper, and nickel also was the site having the highest computed yield for total solids.

Chemoselective chromium(II)-catalyzed cross-coupling reactions of dichlorinated heteroaromatics with functionalized aryl grignard reagents.

PubMed

Steib, Andreas K; Kuzmina, Olesya M; Fernandez, Sarah; Malhotra, Sushant; Knochel, Paul

2015-01-26

Chromium(II) chloride catalyzes the chemoselective cross-coupling reaction of dichloropyridines with a range of functionalized (hetero)aromatic Grignard reagents at room temperature. Functional groups, such as esters and acetals, are well tolerated in this transformation. Previously challenging substrates, quinolines and isoquinolines, participate in the selective Cr-catalyzed cross-coupling in cyclopentyl methyl ether (CPME) as the solvent. The effective purging of Cr salts is demonstrated by using various solid supports. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Procedure to Determine the Coordinated Chromium and Calcium Isotopic Composition of Astromaterials Including the Chelyabinsk Meteorite

NASA Technical Reports Server (NTRS)

Tappa, M. J.; Mills, R. D.; Ware, B.; Simon, J. I.

2014-01-01

The isotopic compositions of elements are often used to characterize nucelosynthetic contributions in early Solar System objects. Coordinated multiple middle-mass elements with differing volatilities may provide information regarding the location of condensation of early Solar System solids. Here we detail new procedures that we have developed to make high-precision multi-isotope measurements of chromium and calcium using thermal ionization mass spectrometry, and characterize a suite of chondritic and terrestrial material including two fragments of the Chelyabinsk LL-chondrite.

Development of Low Cost Filler Materials for Welding High Strength Steels.

DTIC Science & Technology

1984-04-29

solid wire form for use in GMAW and GTAW welding of HY-130, Linde 140S and Airco AXI40. As can be seen from Table 2, they achieve their properties with...as pure powder and ferroalloys, 16 2 ’ Transfer efficiencies of elements (e.g. Nickel, Chromium and Molybdenum) from the electrode to weld metal then...chemical compositions of the deposits (as shown in Table 5) was "lean" in carbon, nickel, manganese and molybdenum but "rich" in chromium , compared to

X-ray Absorption and Emission Spectroscopy of CrIII (Hydr)Oxides: Analysis of the K-Pre-Edge Region

NASA Astrophysics Data System (ADS)

Frommer, Jakob; Nachtegaal, Maarten; Czekaj, Izabela; Weng, Tsu-Chien; Kretzschmar, Ruben

2009-10-01

Pre-edge spectral features below the main X-ray absorption K-edge of transition metals show a pronounced chemical sensitivity and are promising sources of structural information. Nevertheless, the use of pre-edge analysis in applied research is limited because of the lack of definite theoretical peak-assignments. The aim of this study was to determine the factors affecting the chromium K-pre-edge features in trivalent chromium-bearing oxides and oxyhydroxides. The selected phases varied in the degree of octahedral polymerization and the degree of iron-for-chromium substitution in the crystal structure. We investigated the pre-edge fine structure by means of high-energy-resolution fluorescence detected X-ray absorption spectroscopy and by 1s2p resonant X-ray emission spectroscopy. Multiplet theory and full multiple-scattering calculations were used to analyze the experimental data. We show that the chromium K-pre-edge contains localized and nonlocalized transitions. Contributions arising from nonlocalized metal-metal transitions are sensitive to the nearest metal type and to the linkage mode between neighboring metal octahedra. Analyzing these transitions opens up new opportunities for investigating the local coordination environment of chromium in poorly ordered solids of environmental relevance.

Green route for the utilization of chrome shavings (chromium-containing solid waste) in tanning industry.

PubMed

Rao, Jonnalagadda Raghava; Thanikaivelan, Palanisamy; Sreeram, Kalarical Janardhanan; Nair, Balachandran Unni

2002-03-15

Chromium-containing wastes from various industrial sectors are under critical review. Leather processing is one such industrial activity that generates chromium-bearing wastes in different forms. One of them is chrome shavings, and this contributes to an extent of 10% of the quantum of raw skins/hides processed, amounting to 0.8 million ton globally. In this study, the high protein content of chrome shavings has been utilized for reduction of chromium(VI) in the preparation of chrome tanning agent. This approach has been exploited for the development of two products: one with chrome shavings alone as reducing agent and the other with equal proportion of chrome shavings and molasses. The developed products exhibit more masking due to the formation of intermediate organic oligopeptides. This has been corroborated through the spectral, hydrolysis, and species-wise distribution studies. The formation of these organic masking agents helps in chrome tanning by shifting the precipitation point of chromium to relatively higher pH levels. Hence, the developed products find use as chrome tanning agents for leather processing, thus providing a means for better utilization of chrome shaving wastes.

Diffusion relaxation times of nonequilibrium isolated small bodies and their solid phase ensembles to equilibrium states

NASA Astrophysics Data System (ADS)

Tovbin, Yu. K.

2017-08-01

The possibility of obtaining analytical estimates in a diffusion approximation of the times needed by nonequilibrium small bodies to relax to their equilibrium states based on knowledge of the mass transfer coefficient is considered. This coefficient is expressed as the product of the self-diffusion coefficient and the thermodynamic factor. A set of equations for the diffusion transport of mixture components is formulated, characteristic scales of the size of microheterogeneous phases are identified, and effective mass transfer coefficients are constructed for them. Allowing for the developed interface of coexisting and immiscible phases along with the porosity of solid phases is discussed. This approach can be applied to the diffusion equalization of concentrations of solid mixture components in many physicochemical systems: the mutual diffusion of components in multicomponent systems (alloys, semiconductors, solid mixtures of inert gases) and the mass transfer of an absorbed mobile component in the voids of a matrix consisting of slow components or a mixed composition of mobile and slow components (e.g., hydrogen in metals, oxygen in oxides, and the transfer of molecules through membranes of different natures, including polymeric).

A review on management of chrome-tanned leather shavings: a holistic paradigm to combat the environmental issues.

PubMed

Pati, Anupama; Chaudhary, Rubina; Subramani, Saravanabhavan

2014-10-01

Raw hide/skins come to the tanners as a by-product of meat industry which is converted into value-added leather as product for fashion market. Leather manufacturing is a chemical process of natural biological matrix. It employs a huge quantity of water and inorganic and organic chemicals for processing and thereby discharges solid and liquid wastes into the environment. One of the potential solid wastes generated from leather industry is chrome-tanned leather shavings (CTLSs), and its disposal is increasingly becoming a huge challenge on disposal to tanners due to presence of heavy metal chromium. Hence, finding a sustainable solution to the CTLS disposal problem is a prime challenge for global tanners and researchers. This paper aims to the deeper review of various disposal methods on CTLS such as protein, chromium, and energy recovery processes and its utilization methodologies. Sustainable technologies have been developed to overcome CTLS solid wastes emanating from leather processing operations. Further, this review paper brings a broader classification of developed methodologies for treatment of CTLSs.

False-positive result when a diphenylcarbazide spot test is used on trivalent chromium-passivated zinc surfaces.

PubMed

Reveko, Valeriia; Lampert, Felix; Din, Rameez U; Thyssen, Jacob P; Møller, Per

2018-05-01

A colorimetric 1,5-diphenylcarbazide (DPC)-based spot test can be used to identify hexavalent chromium on various metallic and leather surfaces. DPC testing on trivalent chromium-passivated zinc surfaces has unexpectedly given positive results in some cases, apparently indicating the presence of hexavalent chromium; however, the presence of hexavalent chromium has never been confirmed with more sensitive and accurate test methods. To examine the presence of hexavalent chromium on trivalent chromium-passivated zinc surfaces with a DPC-based spot test. A colorimetric DPC spot test was used for the initial detection of hexavalent chromium on new and 1-year-aged trivalent chromium-passivated zinc surfaces. Then, X-ray photoelectron spectroscopy (XPS) was performed for all samples. The DPC spot test indicated the presence of hexavalent chromium in aged, but not new, trivalent chromium passivation on zinc; however, subsequent analysis by XPS could not confirm the presence of chromium in a hexavalent state. Unintended oxidation of DPC induced by atmospheric corrosion is suggested as a possible reason for the false-positive reaction of the DPC test on a trivalent chromium-passivated zinc surface. Further validation of the use of the DPC test for chromium-containing metallic surfaces is required. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Ionization behavior of polyphosphoinositides determined via the preparation of pH titration curves using solid-state 31P NMR.

PubMed

Graber, Zachary T; Kooijman, Edgar E

2013-01-01

Detailed knowledge of the degree of ionization of lipid titratable groups is important for the evaluation of protein-lipid and lipid-lipid interactions. The degree of ionization is commonly evaluated by acid-base titration, but for lipids localized in a multicomponent membrane interface this is not a suitable technique. For phosphomonoester-containing lipids such as the polyphosphoinositides, phosphatidic acid, and ceramide-1-phosphate, this is more conveniently accomplished by (31)P NMR. Here, we describe a solid-state (31)P NMR procedure to construct pH titration curves to determine the degree of ionization of phosphomonoester groups in polyphosphoinositides. This procedure can also be used, with suitable sample preparation conditions, for other important signaling lipids. Access to a solid-state, i.e., magic angle spinning, capable NMR spectrometer is assumed. The procedures described here are valid for a Bruker instrument, but can be adapted for other spectrometers as needed.

Process for the Production of Star Tracklng [Tracking] Reticles

NASA Technical Reports Server (NTRS)

Smith, Wade O. (Inventor); Toft, Albert R. (Inventor)

1972-01-01

A method for the production of reticles, particularly those for use in outer space, wherein the product is a quartz base coated with highly adherent layers of chromium, chromium-silver, and silver vacuum deposited through a mask, and then coated with an electrodeposit of copper from a copper sulfate solution followed by an electrodeposit of black chromium. The masks are produced by coating a beryllium-copper alloy substrate with a positive working photoresist, developing the photoresist according to a pattern to leave a positive mask, plating uncoated areas with gold, removing the photoresist, coating the substrate with a negative working photoresist, developing the negative working photoresist to expose the base metal of the pattern, and chemically etching the unplated side of the pattern to produce the mask. The mask produced is then used in the vacuum deposition of: (1) chromium metal on the surface of a quartz base to obtain a highly adherent quartz-chromium interface; (2) silver on the chromium deposit, during the final stage of chromium deposit, to produce a silver chromium alloy layer; and (3) silver onto the surface of the alloy layer. The coated quartz base is then coated by electroplating utilizing an acid copper deposit followed by a black chromium electrodeposit to produce the product of the present invention.

Pharmacokinetic Modeling of Trivalent and Hexavalent Chromium Based on Ingestion and Inhalation of Soluble Chromium Compounds.

DTIC Science & Technology

1991-12-01

34 0-0-° AD-A256 238 - DTIC 7 ELECTE A S OCTI 6 1992 R CM S PHARMACOKINETIC MODELING OF T TRIVALENT AND HEXAVALENT CHROMIUM R BASED ON INGESTION AND...or inhalation of trivalent or hexavalent soluble chromium compounds. The research described herein began in June 1990 and was completed in December... trivalent and hexavalent chromium compounds, chromic chloride-hexahydrate and sodium dichromate, respectively (Table I). An inhalation control group was

A physiologically based model of chromium kinetics in the rat.

PubMed

O'Flaherty, E J

1996-05-01

A physiologically based model of chromium kinetics in rats has been developed. The general structure of the model is similar to that of a model of lead kinetics in rats. Like lead chromium exchanges between plasma and the bone surfaces in contact with plasma, and also like lead, although with much lower efficiency, it can become incorporated into actively mineralizing bone. Both processes are included in the model. Parallel absorption and disposition schemes for chromium(VI) and chromium(III) are linked in the model by reduction processes occurring throughout the body, including the lung and gastrointestinal tract. Examination of a number of data sets from studies in which chromium salts were administered to rats intravenously, orally, or by intratracheal instillation established that intravenous administration, on the one hand, and oral or pulmonary administration, on the other hand, result in different disposition patterns. The model was calibrated based on published oral and intratracheal kinetic studies in rats given soluble chromium(III) and chromium(VI) salts. In the most complete of these studies, chromium concentrations were monitored in individual tissues for 42 days following intratracheal administration of a soluble chromium(VI) salt. Inclusion in the model of a urinary excretion delay was necessary in order to fit excretion data from two other intratracheal studies. Model predictions of blood chromium concentrations are compared with the results of a published kinetic study in which rats were administered a soluble chromium(VI) salt by inhalation.

A New All Solid State Approach to Gaseous Pollutant Detection

NASA Technical Reports Server (NTRS)

Brown, V.; Tamstorf, K.

1971-01-01

Recent efforts in our laboratories have concentrated on the development of an all solid state gas sensor, by combining solid electrolyte (ion exchange membrane) technology with advanced thin film deposition processes. With the proper bias magnitude and polarity these miniature electro-chemical,cells show remarkable current responses for many common pollution gases. Current activity is now focused on complementing a multiple array (matrix) of these solid state sensors, with a digital electronic scanner device possessing "scan-compare-identify-alarm: capability. This innovative approach to multi-component pollutant gas analysis may indeed be the advanced prototype for the "third generation" class of pollution analysis instrumentation so urgently needed in the decade ahead.

Utilization of modified corn silk as a biosorbent for solid-phase extraction of Cr(III) and chromium speciation.

PubMed

Yu, Hongmei; Pang, Jing; Wu, Mei; Wu, Qiaoli; Huo, Cuixiu

2014-01-01

The ues of corn silk modified with diluted nitric acid (HNO3-MCS) as a novel biosorbent has been established for solid-phase extraction of Cr(III) and chromium speciation in water samples. The functional groups of the HNO3-MCS surface are favorable for the adsorption of Cr(III). Effective extraction conditions were optimized in both batch and column methods. At pH 3.0 - 6.0, a discrimination of Cr(III) and Cr(VI) is achieved on the HNO3-MCS surface. Cr(III) ions are retained onto the HNO3-MCS surface, however, the adsorption of Cr(VI) is negligible under the same conditions. The adsorption isotherm of HNO3-MCS for Cr(III) has been demonstrated in accordance with a linear form of the Langmuir equation, and the maximum adsorption capacity is 35.21 mg g(-1). The well fitted linear regression of the pseudo-second order model showed the indication of a chemisorption mechanism for the entire concentration range. Thermodynamic studies have shown that the adsorption process is spontaneous and endothermic. The adsorbed Cr(III) was quantitatively eluted by a nitric acid solution with detection by flame atomic absorption spectrometry (FAAS). With a sample volume of 30 mL, a detection limit (3σ) of 0.85 μg L(-1) and a precision of 2.0% RSD at the 40 μg L(-1) level were achieved. The concentration of Cr(III) could be accurately quantified within a linear range of 3 - 200 μg L(-1). After Cr(VI) has been reduced to Cr(III) with hydroxylamine hydrochloride, the total amount of chromium was obtained, and the content of Cr(VI) was given by subtraction. The procedure was validated by analyzing chromium in a certified reference material (GBW (E) 080039). It was also successfully applied for the speciation of chromium in wastewater samples.

Multiscale Transient and Steady-State Study of the Influence of Microstructure Degradation and Chromium Oxide Poisoning on Solid Oxide Fuel Cell Cathode Performance

NASA Astrophysics Data System (ADS)

Li, Guanchen; von Spakovsky, Michael R.; Shen, Fengyu; Lu, Kathy

2018-01-01

Oxygen reduction in a solid oxide fuel cell cathode involves a nonequilibrium process of coupled mass and heat diffusion and electrochemical and chemical reactions. These phenomena occur at multiple temporal and spatial scales, making the modeling, especially in the transient regime, very difficult. Nonetheless, multiscale models are needed to improve the understanding of oxygen reduction and guide cathode design. Of particular importance for long-term operation are microstructure degradation and chromium oxide poisoning both of which degrade cathode performance. Existing methods are phenomenological or empirical in nature and their application limited to the continuum realm with quantum effects not captured. In contrast, steepest-entropy-ascent quantum thermodynamics can be used to model nonequilibrium processes (even those far-from equilibrium) at all scales. The nonequilibrium relaxation is characterized by entropy generation, which can unify coupled phenomena into one framework to model transient and steady behavior. The results reveal the effects on performance of the different timescales of the varied phenomena involved and their coupling. Results are included here for the effects of chromium oxide concentrations on cathode output as is a parametric study of the effects of interconnect-three-phase-boundary length, oxygen mean free path, and adsorption site effectiveness. A qualitative comparison with experimental results is made.

Modeling the Hydrogen Solubility in Liquid Aluminum Alloys

NASA Astrophysics Data System (ADS)

Harvey, Jean-Philippe; Chartrand, Patrice

2010-08-01

The modeling of hydrogen solubility in multicomponent Al-(Li, Mg, Cu, and Si) liquid phase has been performed with a thermodynamic approach using the modified quasichemical model with the pair approximation (MQMPA). All hydrogen solubility data available in literature was assessed critically to obtain the binary parameters of the MQMPA model for the Al-H, Li-H, Mg-H, Cu-H, Zn-H, and Si-H melts. For the Li-H system, a new thermodynamic description of the stable solid lithium hydride was determined based on the c p found in literature. The thermodynamic model for the Al-Li system also was reassessed in this work to take into account the short-range ordering observed for this system. Built-in interpolation techniques allow the model to estimate the thermodynamic properties of the multicomponent liquid solution from the liquid model parameters of the lower order subsystems. A comparison of the calculated hydrogen solubility performed at various equilibrium conditions of temperature, pressure, and composition with the available experimental data found in the literature is presented in this work, as well as a comparison with some results from previous modeling.

Rapid quantification of multi-components in alcohol precipitation liquid of Codonopsis Radix using near infrared spectroscopy (NIRS).

PubMed

Luo, Yu; Li, Wen-Long; Huang, Wen-Hua; Liu, Xue-Hua; Song, Yan-Gang; Qu, Hai-Bin

2017-05-01

A near infrared spectroscopy (NIRS) approach was established for quality control of the alcohol precipitation liquid in the manufacture of Codonopsis Radix. By applying NIRS with multivariate analysis, it was possible to build variation into the calibration sample set, and the Plackett-Burman design, Box-Behnken design, and a concentrating-diluting method were used to obtain the sample set covered with sufficient fluctuation of process parameters and extended concentration information. NIR data were calibrated to predict the four quality indicators using partial least squares regression (PLSR). In the four calibration models, the root mean squares errors of prediction (RMSEPs) were 1.22 μg/ml, 10.5 μg/ml, 1.43 μg/ml, and 0.433% for lobetyolin, total flavonoids, pigments, and total solid contents, respectively. The results indicated that multi-components quantification of the alcohol precipitation liquid of Codonopsis Radix could be achieved with an NIRS-based method, which offers a useful tool for real-time release testing (RTRT) of intermediates in the manufacture of Codonopsis Radix.

Thermal and hydrometallurgical recovery methods of heavy metals from municipal solid waste fly ash.

PubMed

Kuboňová, L; Langová, Š; Nowak, B; Winter, F

2013-11-01

Heavy metals in fly ash from municipal solid waste incinerators are present in high concentrations. Therefore fly ash must be treated as a hazardous material. On the other hand, it may be a potential source of heavy metals. Zinc, lead, cadmium, and copper can be relatively easily removed during the thermal treatment of fly ash, e.g. in the form of chlorides. In return, wet extraction methods could provide promising results for these elements including chromium and nickel. The aim of this study was to investigate and compare thermal and hydrometallurgical treatment of municipal solid waste fly ash. Thermal treatment of fly ash was performed in a rotary reactor at temperatures between 950 and 1050°C and in a muffle oven at temperatures from 500 to 1200°C. The removal more than 90% was reached by easy volatile heavy metals such as cadmium and lead and also by copper, however at higher temperature in the muffle oven. The alkaline (sodium hydroxide) and acid (sulphuric acid) leaching of the fly ash was carried out while the influence of temperature, time, concentration, and liquid/solid ratio were investigated. The combination of alkaline-acidic leaching enhanced the removal of, namely, zinc, chromium and nickel. Copyright © 2013 Elsevier Ltd. All rights reserved.

Tetravalent chromium (Cr(4+)) as laser-active ion for tunable solid-state lasers

NASA Technical Reports Server (NTRS)

Seas, A.; Petricevic, V.; Alfano, Robert R.

1992-01-01

Generation of femtosecond pulses from a continuous-wave mode-locked chromium-doped forsterite (Cr(4+):Mg2SiO4) laser has been accomplished. The forsterite laser was actively mode-locked using an acousto-optic modulator operating at 78 MHz with two Brewster high-dispersion glass prisms for intra-cavity chirp compensation. Transform-limited sub-100-fs pulses were routinely generated in the TEM(sub 00) mode with 85 mW of continuous power (with 1 percent output coupler), tunable over 1230-1280 nm. The shortest pulses of 60-fs pulsewidth were measured.

Modeling multicomponent ion exchange equilibrium utilizing hydrous crystalline silicotitanates by a multiple interactive ion exchange site model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Z.; Anthony, R.G.; Miller, J.E.

1997-06-01

An equilibrium multicomponent ion exchange model is presented for the ion exchange of group I metals by TAM-5, a hydrous crystalline silicotitanate. On the basis of the data from ion exchange and structure studies, the solid phase is represented as Na{sub 3}X instead of the usual form of NaX. By using this solid phase representation, the solid can be considered as an ideal phase. A set of model ion exchange reactions is proposed for ion exchange between H{sup +}, Na{sup +}, K{sup +}, Rb{sup +}, and Cs{sup +}. The equilibrium constants for these reactions were estimated from experiments with simplemore » ion exchange systems. Bromley`s model for activity coefficients of electrolytic solutions was used to account for liquid phase nonideality. Bromley`s model parameters for CsOH at high ionic strength and for NO{sub 2}{sup {minus}} and Al(OH){sub 4}{sup {minus}} were estimated in order to apply the model for complex waste simulants. The equilibrium compositions and distribution coefficients of counterions were calculated for complex simulants typical of DOE wastes by solving the equilibrium equations for the model reactions and material balance equations. The predictions match the experimental results within 10% for all of these solutions.« less

Development of a Method for the Determination of Chromium and Cadmium in Tannery Wastewater Using Laser-Induced Breakdown Spectroscopy

PubMed Central

Bukhari, Mahwish; Awan, M. Ali; Qazi, Ishtiaq A.; Baig, M. Anwar

2012-01-01

This paper illustrates systematic development of a convenient analytical method for the determination of chromium and cadmium in tannery wastewater using laser-induced breakdown spectroscopy (LIBS). A new approach was developed by which liquid was converted into solid phase sample surface using absorption paper for subsequent LIBS analysis. The optimized values of LIBS parameters were 146.7 mJ for chromium and 89.5 mJ for cadmium (laser pulse energy), 4.5 μs (delay time), 70 mm (lens to sample surface distance), and 7 mm (light collection system to sample surface distance). Optimized values of LIBS parameters demonstrated strong spectrum lines for each metal keeping the background noise at minimum level. The new method of preparing metal standards on absorption papers exhibited calibration curves with good linearity with correlation coefficients, R2 in the range of 0.992 to 0.998. The developed method was tested on real tannery wastewater samples for determination of chromium and cadmium. PMID:22567570

A new method for multicomponent activity coefficients of electrolytes in aqueous atmospheric aerosols

NASA Astrophysics Data System (ADS)

Zaveri, Rahul A.; Easter, Richard C.; Wexler, Anthony S.

2005-01-01

Three-dimensional models of atmospheric inorganic aerosols need accurate and computationally efficient parameterizations of activity coefficients of various electrolytes in multicomponent aqueous solutions. In this paper, we extend the Taylor's series expansion mixing rule used by C. Wagner in 1952 for estimating activity coefficients in dilute alloy solutions to aqueous electrolyte solutions at any concentration. The resulting method, called the multicomponent Taylor expansion method (MTEM), estimates the mean activity coefficient of an electrolyte in a multicomponent solution on the basis of its values in binary solutions of all the electrolytes present in the mixture at the solution water activity aw, assuming aw is equal to the ambient relative humidity. MTEM is applied here for atmospheric aerosol systems containing H+, NH4+, Na+, Ca2+, SO42-, HSO4-, NO3-, and Cl- ions. The aerosol water content is calculated using the Zdanovskii-Stokes-Robinson (ZSR) method. For self-consistency, most of the MTEM and ZSR parameters are derived using the comprehensive Pitzer-Simonson-Clegg model at 298.15 K and are valid for an aw range of 0.2-0.97. Because CaSO4 is sparingly soluble, it is treated as a solid in the model over the entire aw range. MTEM is evaluated for several multicomponent systems representing various continental and marine aerosols and is contrasted against the mixing rule of C. L. Kusik and H. P. Meissner and of L. A. Bromley and the newer approach of S. Metzger and colleagues. Predictions of MTEM are found to be generally within a factor of 0.8-1.25 of the comprehensive Pitzer-Simonson-Clegg model and are shown to be significantly more accurate than predictions of the other three methods. MTEM also yields a noniterative solution of the bisulfate ion dissociation in sulfate-rich systems: a major computational advantage over other ionic-strength-based methods that require an iterative solution. CPU time requirements of MTEM relative to other methods for sulfate-poor and sulfate-rich systems are also discussed.

Phytoremediation of industrial mines wastewater using water hyacinth.

PubMed

Saha, Priyanka; Shinde, Omkar; Sarkar, Supriya

2017-01-02

The wastewater at Sukinda chromite mines (SCM) area of Orissa (India) showed high levels of toxic hexavalent chromium (Cr VI). Wastewater from chromium-contaminated mines exhibit potential threats for biotic community in the vicinity. The aim of the present investigation is to develop a suitable phytoremediation technology for the effective removal of toxic hexavalent chromium from mines wastewater. A water hyacinth species Eichhornia crassipes was chosen to remediate the problem of Cr (VI) pollution from wastewater. It has been observed that this plant was able to remove 99.5% Cr (VI) of the processed water of SCM in 15 days. This aquatic plant not only removed hexavalent Cr, but is also capable of reducing total dissolved solids (TDS), biological oxygen demand (BOD), chemical oxygen demand (COD), and other elements of water also. Large-scale experiment was also performed using 100 L of water from SCM and the same removal efficiency was achieved.

Phytoremediation of industrial mines wastewater using water hyacinth

PubMed Central

Saha, Priyanka; Shinde, Omkar; Sarkar, Supriya

2017-01-01

ABSTRACT The wastewater at Sukinda chromite mines (SCM) area of Orissa (India) showed high levels of toxic hexavalent chromium (Cr VI). Wastewater from chromium-contaminated mines exhibit potential threats for biotic community in the vicinity. The aim of the present investigation is to develop a suitable phytoremediation technology for the effective removal of toxic hexavalent chromium from mines wastewater. A water hyacinth species Eichhornia crassipes was chosen to remediate the problem of Cr (VI) pollution from wastewater. It has been observed that this plant was able to remove 99.5% Cr (VI) of the processed water of SCM in 15 days. This aquatic plant not only removed hexavalent Cr, but is also capable of reducing total dissolved solids (TDS), biological oxygen demand (BOD), chemical oxygen demand (COD), and other elements of water also. Large-scale experiment was also performed using 100 L of water from SCM and the same removal efficiency was achieved. PMID:27551860

A fundamental study of chromium deposition on solid oxide fuel cell cathode materials

NASA Astrophysics Data System (ADS)

Tucker, Michael C.; Kurokawa, Hideto; Jacobson, Craig P.; De Jonghe, Lutgard C.; Visco, Steven J.

Chromium contamination of metal oxides and SOFC cathode catalysts is studied in the range 700-1000 °C. Samples are exposed to a moist air atmosphere saturated with volatile Cr species in the presence and absence of direct contact between the sample and ferritic stainless steel powder. Chromium contamination of the samples is observed to occur via two separate pathways: surface diffusion from the stainless steel surface and vapor deposition from the atmosphere. Surface diffusion dominates in all cases. Surface diffusion is found to be a significant source of Cr contamination for LSM and LSCF at 700, 800, and 1000 °C. Vapor deposition of Cr onto LSCF was observed at each of these temperatures, but was not observed for LSM at 700 or 800 °C. Comparison of the behavior for LSM, LSCF, and single metal oxides suggests that Mn and Co, respectively, are responsible for the Cr contamination of these catalysts.

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

PubMed Central

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

2015-01-01

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

Effect of Antifoam Agent on Oxidative Leaching of Hanford Tank Sludge Simulants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapko, Brian M.; Jones, Susan A.; Lumetta, Gregg J.

2010-02-26

Oxidative leaching of simulant tank waste containing an antifoam agent (AFA) to reduce the chromium content of the sludge was tested using permanganate as the oxidant in 0.25 M NaOH solutions. AFA is added to the waste treatment process to prevent foaming. The AFA, Dow Corning Q2-3183A, is a surface-active polymer that consists of polypropylene glycol, polydimethylsiloxane, octylphenoxy polyethoxy ethanol, treated silica, and polyether polyol. Some of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) waste slurries contain high concentrations of undissolved solids that would exhibit undesirable behavior without AFA addition. These tests were conducted to determine the effectmore » of the AFA on oxidative leaching of Cr(III) in waste by permanganate. It has not previously been determined what effect AFA has on the permanganate reaction. This study was conducted to determine the effect AFA has on the oxidation of the chromium, plus plutonium and other criticality-related elements, specifically Fe, Ni and Mn. During the oxidative leaching process, Mn is added as liquid permanganate solution and is converted to an insoluble solid that precipitates as MnO2 and becomes part of the solid waste. Caustic leaching was performed followed by an oxidative leach at either 25°C or 45°C. Samples of the leachate and solids were collected at each step of the process. Initially, Battelle-Pacific Northwest Division (PNWD) was contracted by Bechtel National, Inc. to perform these further scoping studies on oxidative alkaline leaching. The data obtained from the testing will be used by the WTP operations to develop procedures for permanganate dosing of Hanford tank sludge solids during oxidative leaching. Work was initially conducted under contract number 24590-101-TSA-W000-00004. In February 2007, the contract mechanism was switched to Pacific Northwest National Laboratory (PNNL) operating Contract DE-AC05-76RL01830. In summary, this report describes work focused on determining the effect of AFA on chromium oxidation by permanganate with Hanford sludge simulant.« less

Lattice mismatch modeling of aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shin, Dongwon; Roy, Shibayan; Watkins, Thomas R.

We present a theoretical framework to accurately predict the lattice mismatch between the fcc matrix and precipitates in the multi-component aluminum alloys as a function of temperature and composition. We use a computational thermodynamic approach to model the lattice parameters of the multi-component fcc solid solution and θ'-Al2Cu precipitate phase. Better agreement between the predicted lattice parameters of fcc aluminum in five commercial alloys (206, 319, 356, A356, and A356 + 0.5Cu) and experimental data from the synchrotron X-ray diffraction (SXD) has been obtained when simulating supersaturated rather than equilibrium solid solutions. We use the thermal expansion coefficient of thermodynamicallymore » stable θ-Al2Cu to describe temperature-dependent lattice parameters of meta-stable θ' and to show good agreement with the SXD data. Both coherent and semi-coherent interface mismatches between the fcc aluminum matrix and θ' in Al-Cu alloys are presented as a function of temperature. Our calculation results show that the concentration of solute atoms, particularly Cu, in the matrix greatly affects the lattice mismatch« less

The effect of pH and triethanolamine on sulfisoxazole complexation with hydroxypropyl-beta-cyclodextrin.

PubMed

Gladys, Granero; Claudia, Garnero; Marcela, Longhi

2003-11-01

A novel complexation of sulfisoxazole with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) was studied. Two systems were used: binary complexes prepared with HP-beta-CD and multicomponent system (HP-beta-CD and the basic compound triethanolamine (TEA)). Inclusion complex formation in aqueous solutions and in solid state were investigated by the solubility method, thermal analysis (differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)), Fourier-transform infrared spectroscopy (FT-IR) and dissolution studies. The solid complexes of sulfisoxazole were prepared by freeze-drying the homogeneous concentrated aqueous solutions in molar ratios of sulfisoxazole:HP-beta-CD 1:1 and 1:2, and sulfisoxazole:TEA:HP-beta-CD 1:1:2. FT-IR and thermal analysis showed differences among sulfisoxazole:HP-beta-CD and sulfisoxazole:TEA:HP-beta-CD and their corresponding physical mixtures and individual components. The HP-beta-CD solubilization of sulfisoxazole could be improved by ionization of the drug molecule through pH adjustments. However, larger improvements of the HP-beta-CD solubilization are obtained when multicomponent systems are used, allowing to reduce the amount of CD necessary to prepare the target formulation.

Chromium(III)-imprinted silica gel for speciation analysis of chromium in environmental water samples with ICP-MS detection.

PubMed

Zhang, Nan; Suleiman, Jibrin Sabo; He, Man; Hu, Bin

2008-04-15

A new chromium(III)-imprinted 3-(2-aminoethylamino) propyltrimethoxysilane (AAPTS)-functionalized silica gel sorbent was synthesized by a surface imprinting technique and was employed as a selective solid-phase extraction material for speciation analysis of chromium in environmental water samples prior to its determination by inductively coupled plasma mass spectrometry (ICP-MS). The prepared Cr(III)-imprinted silica gel shows the selectivity coefficient of more than 700 for Cr(III) in the presence of Mn(II). The static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Cr(III) were 30.5 mg g(-1) and 13.4 mg g(-1). It was also found that Cr(VI) could be adsorbed at low pH by the prepared imprinted silica gel, and this finding makes it feasible to enrich and determine Cr(VI) at low pH without adding reducing reagents. The imprinted silica gel sorbent offered a fast kinetics for the adsorption and desorption of both chromium species. Under the optimized conditions, the detection limits of 4.43 pg mL(-1) and 8.30 pg mL(-1) with the relative standard deviations (R.S.D.s) of 4.44% and 4.41% (C=0.5 ng mL(-1), n=7) for Cr(III) and Cr(VI) were obtained, respectively. The proposed method was successfully applied to the speciation of trace chromium in environmental water samples. To validate the proposed method, two certified reference materials were analyzed and the determined values were in a good agreement with the certified values. The developed method is rapid, selective, sensitive and applicable for the speciation of trace chromium in environmental water samples.

Mechanosynthesis of A Ferritic ODS (Oxide Dispersion Strengthened) Steel Containing 14% Chromium and Its Characterization

NASA Astrophysics Data System (ADS)

Rivai, A. K.; Dimyati, A.; Adi, W. A.

2017-05-01

One of the advanced materials for application at high temperatures which is aggressively developed in the world is ODS (Oxide Dispersion strengthened) steel. ODS ferritic steels are one of the candidate materials for future nuclear reactors in the world (Generation IV reactors) because it is able to be used in the reactor above 600 °C. ODS ferritic steels have also been developed for the interconnect material of SOFC (Solid Oxide Fuel Cell) which will be exposed to about 800 °C of temperature. The steel is strengthened by dispersing homogeneously of oxide particles (ceramic) in nano-meter sized in the matrix of the steel. Synthesis of a ferritic ODS steel by dispersion of nano-particles of yttrium oxide (yttria: Y2O3) as the dispersion particles, and containing high-chromium i.e. 14% has been conducted. Synthesis of the ODS steels was done mechanically (mechanosynthesis) using HEM (High Energy ball Milling) technique for 40 and 100 hours. The resulted samples were characterized using SEM-EDS (Scanning Electron Microscope-Energy Dispersive Spectroscope), and XRD (X-ray diffraction) to analyze the microstructure characteristics. The results showed that the crystal grains of the sample with 100 hours milling time was much smaller than the sample with 40 hours milling time, and some amount of alloy was formed during the milling process even for 40 hours milling time. Furthermore, the structure analysis revealed that some amount of iron atom substituted by a slight amount of chromium atom as a solid solution. The quantitative analysis showed that the phase mostly consisted of FeCr solid-solution with the structure was BCC (body-centered cubic).

Multicomponent patterned ultrathin carbon nanomembranes by laser ablation

NASA Astrophysics Data System (ADS)

Frese, Natalie; Scherr, Julian; Beyer, André; Terfort, Andreas; Gölzhäuser, Armin; Hampp, Norbert; Rhinow, Daniel

2018-01-01

Carbon nanomembranes (CNMs) are a class of two-dimensional materials, which are obtained by electron beam-induced crosslinking of aromatic self-assembled monolayers (SAMs) on solid substrates. CNMs made from a single type of precursor molecule are uniform with homogeneous chemical and physical properties. We have developed a method for the fabrication of internally patterned CNMs resembling a key feature of biological membranes. Direct laser patterning is used to obtain multicomponent patterned SAMs on gold, which are subsequently crosslinked by electron irradiation. We demonstrate that the structure of internally patterned CNMs is preserved upon transfer to different substrates. The method enables rapid fabrication of patterned 2D materials with local variations in chemical and physical properties on the micrometer to centimeter scale.

Materials and energy flow in the life cycle of leather: a case study of Bangladesh

NASA Astrophysics Data System (ADS)

Chowdhury, Zia Uddin Md.; Ahmed, Tanvir; Hashem, Md. Abul

2018-05-01

This article presents the results of the materials and energy flow analysis for leather produced in Bangladesh and establishes an inventory for the life cycle assessment. Also, a comparison is made with the material and energy flow of the Indian leather. A cradle to gate analysis is performed for full-chrome leather (FCL), a representative leather article from an export-oriented industry in Bangladesh, taking into consideration the main processes associated with leather production and the corresponding materials and energy input. Data was collected on annual wet-salted rawhide consumption, water, and steam consumption, chemicals requirement, tannery solid waste generation, electricity, fuel oil use for the generator and steam boiler. Moreover, an analysis of the physical and chemical properties of wastewater emissions of the different leather unit processes was performed. The input and output profiles of the FCL were compared to those of an Indian leather. It was seen that FCL consumed water 2 times higher than the Indian leather while the electricity consumption of Indian leather was almost 2 times higher than its Bangladeshi counterpart. The Indian leather had significantly higher carbon footprint (in terms of CO2 equivalent emission) mainly because of the consumption of grid electricity that comes from coal-based power generation. Wastewater parameters such as chloride, Total Dissolved Solids (TDS) and Total Solids (TS) for the Indian leather are more than 4.5, 3 and 3 times higher respectively than that of corresponding emissions for the Bangladeshi FCL, which can be attributed to the higher use of inorganic salts in the process. Despite similar input of chromium compounds for both the leathers, the emission of total chromium was slightly higher in the case of Indian leather probably due to lower uptake of chromium by the substrate. Bangladeshi FCL used twice in the amount of (NH4)2SO4 than India, which may be responsible for the higher BOD load in the wastewater. It can also be seen that a significant amount of rawhide input is not converted into the usable leather as demonstrated by the high proportion of solid waste generation (70% and 55% for Bangladeshi FCL and Indian leather respectively). This study highlights that wide variations exist in the materials and energy flows from different tanneries. Understanding these variations is essential to pinpoint areas where resources can be used more efficiently and optimally in the leather manufacturing process.

Thermal Effects on a Low Cr Modification of PS304 Solid Lubricant Coating

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.; Yanke, Anne M.; DellaCorte, Christopher

2004-01-01

PS304 is a high temperature composite solid lubricant coating composed of Ni-Cr, Cr2O3, BaF2-CaF2 and Ag. The effect of reducing chromium content on the formation of voids in the Ni-Cr particles after heat treatment in PS304 coating was investigated. Coatings were prepared with Ni-20Cr or Ni-10Cr powder and in various combinations with the other constituents of PS304 (i.e., chromia, silver and eutectic BaF2-CaF2 powders) and deposited on metal substrates by plasma spray. Specimens were exposed to 650 C for 24 hr or 1090 C for 15 hr and then examined for changes in thickness, coating microstructure and adhesion strength. Specimens with Ni-10Cr generally had less thickness increase than specimens with Ni-20Cr, but there was great variance in the data. Reduction of chromium concentration in Ni-Cr powder tended to reduce the appearance of voids in the Ni-Cr phase after heat exposure. The presence of BaF2-CaF2 resulted in a significant increase in coating adhesion strength after heat treatment, while coatings without BaF2-CaF2 had no significant change. Chemical composition analysis suggested that the void formation was due to oxidation of chromium in the Ni-Cr constituent.

Plant Line Trial Evaluation of Viable Non-Chromium Passivation Systems for Electrolytin Tinplate, ETP (TRP 9911)

DOE Office of Scientific and Technical Information (OSTI.GOV)

John A. Sinsel

2003-06-30

Plant trial evaluations have been completed for two zirconium-based, non-chromium passivation systems previously identified as possible alternatives to cathodic dichromate (CDC) passivation for electrolytic tinplate (ETP). These trials were done on a commercial electrolytic tin plating line at Weirton Steel and extensive evaluations of the materials resulting from these trials have been completed. All this was accomplished as a collaborative effort under the AISI Technology Roadmap Program and was executed by seven North American Tin Mill Products producers [Bethlehem Steel (now acquired by International Steel Group (ISG)), Dofasco Inc., National Steel (now acquired by U.S. Steel), U.S. Steel, USS-Posco, Weirtonmore » Steel, and Wheeling-Pittsburgh Steel] with funding partially from the Department of Energy (DOE) and partially on an equal cost sharing basis among project participants. The initial phases of this project involved optimization of application procedures for the non-chromium systems in the laboratories at Bethlehem Steel and Betz Dearborn followed by extensive testing with various lacquer formulations and food simulants in the laboratories at Valspar and PPG. Work was also completed at Dofasco and Weirton Steel to develop methods to prevent precipitation of insoluble solids as a function of time from the zirconate system. The results of this testing indicated that sulfide staining characteristics for the non-chromium passivation systems could be minimized but not totally eliminated and neither system was found to perform quite as good, in this respect, as the standard CDC system. As for the stability of zirconate treatment, a method was developed to stabilize this system for a sufficient period of time to conduct plant trial evaluations but, working with a major supplier of zirconium orthosulfate, a method for long term stabilization is still under development.« less

Stabilization of chromium-bearing electroplating sludge with MSWI fly ash-based Friedel matrices.

PubMed

Qian, Guangren; Yang, Xiaoyan; Dong, Shixiang; Zhou, Jizhi; Sun, Ying; Xu, Yunfeng; Liu, Qiang

2009-06-15

This work investigated the feasibility and effectiveness of MSWI fly ash-based Friedel matrices on stabilizing/solidifying industrial chromium-bearing electroplating sludge using MSWI fly ash as the main raw material with a small addition of active aluminum. The compressive strength, leaching behavior and chemical speciation of heavy metals and hydration phases of matrices were characterized by TCLP, XRD, FTIR and other experimental methods. The results revealed that MSWI fly ash-based Friedel matrices could effectively stabilize chromium-bearing electroplating sludge, the formed ettringite and Friedel phases played a significant role in the fixation of heavy metals in electroplating sludge. The co-disposal of chromium-bearing electroplating sludge and MSWI fly ash-based Friedel matrices with a small addition of active aluminum is promising to be an effective way of stabilizing chromium-bearing electroplating sludge.

Solid-phase equilibria on Pluto's surface

NASA Astrophysics Data System (ADS)

Tan, Sugata P.; Kargel, Jeffrey S.

2018-03-01

Pluto's surface is covered by volatile ices that are in equilibrium with the atmosphere. Multicomponent phase equilibria may be calculated using a thermodynamic equation of state and, without additional assumptions, result in methane-rich and nitrogen-rich solid phases. The former is formed at temperature range between the atmospheric pressure-dependent sublimation and condensation points, while the latter is formed at temperatures lower than the sublimation point. The results, calculated for the observed 11 μbar atmospheric pressure and composition, are consistent with recent work derived from observations by New Horizons.

LEATHER TANNERY WASTE MANAGEMENT THROUGH PROCESS CHANGE, REUSE AND PRETREATMENT

EPA Science Inventory

Reduction of tannery waste, i.e., trivalent chromium, sulfide and oil and grease components has been accomplished by process change. Protein recovery and hydroclonic separation of solids was shown to be possible in tannery processing in reducing waste loading. All waste load redu...

Multicomponent Reactions in Ligation and Bioconjugation Chemistry.

PubMed

Reguera, Leslie; Méndez, Yanira; Humpierre, Ana R; Valdés, Oscar; Rivera, Daniel G

2018-05-25

Multicomponent reactions (MCRs) encompass an exciting class of chemical transformations that have proven success in almost all fields of synthetic organic chemistry. These convergent procedures incorporate three or more reactants into a final product in one pot, thus combining high levels of complexity and diversity generation with low synthetic cost. Striking applications of these processes are found in heterocycle, peptidomimetic, and natural product syntheses. However, their potential in the preparation of large macro- and biomolecular constructs has been realized just recently. This Account describes the most relevant results of our group in the utilization of MCRs for ligation/conjugation of biomolecules along with significant contributions from other laboratories that validate the utility of this special class of bioconjugation process. Thus, MCRs have proven to be efficient in the ligation of lipids to peptides and oligosaccharides as well as the ligation of steroids, carbohydrates, and fluorescent and affinity tags to peptides and proteins. In the field of glycolipids, we highlight the power of isocyanide-based MCRs with the one-pot double lipidation of glycan fragments functionalized as either the carboxylic acid or amine. In peptide chemistry, the versatility of the multicomponent ligation strategy is demonstrated in both solution-phase lipidation protocols and solid-phase procedures enabling the simultaneous lipidation and biotinylation of peptides. In addition, we show that MCRs are powerful methods for synchronized lipidation/labeling and macrocyclization of peptides, thus accomplishing in one step what usually requires long sequences. In the realm of protein bioconjugation, MCRs have also proven to be effective in labeling, site-selective modification, immobilization, and glycoconjugation processes. For example, we illustrate a successful application of multicomponent polysaccharide-protein conjugation with the preparation of multivalent glycoconjugate vaccine candidates by the ligation of two antigenic capsular polysaccharides of a pathogenic bacterium to carrier proteins. By highlighting the ability to join several biomolecules in only one synthetic operation, we hope to encourage the biomolecular chemistry community to apply this powerful chemistry to novel biomedicinal challenges.

Dual-phase Cr-Ta alloys for structural applications

DOEpatents

Liu, Chain T.; Brady, Michael P.; Zhu, Jiahong; Tortorelli, Peter F.

2001-01-01

Dual phase alloys of chromium containing 2 to 11 atomic percent tantalum with minor amounts of Mo, Cr, Ti, Y, La, Cr, Si and Ge are disclosed. These alloys contain two phases including Laves phase and Cr-rich solid solution in either eutectic structures or dispersed Laves phase particles in the Cr-rich solid solution matrix. The alloys have superior mechanical properties at high temperature and good oxidation resistance when heated to above 1000.degree. C. in air.

Multicomponent self-assembly as a tool to harness new properties from peptides and proteins in material design.

PubMed

Okesola, Babatunde O; Mata, Alvaro

2018-05-21

Nature is enriched with a wide variety of complex, synergistic, and highly functional protein-based multicomponent assemblies. As such, nature has served as a source of inspiration for using multicomponent self-assembly as a platform to create highly ordered, complex, and dynamic protein and peptide-based nanostructures. Such an assembly system relies on the initial interaction of distinct individual building blocks leading to the formation of a complex that subsequently assembles into supramolecular architectures. This approach not only serves as a powerful platform for gaining insight into how proteins co-assemble in nature but also offers huge opportunities to harness new properties not inherent in the individual building blocks. In the past decades, various multicomponent self-assembly strategies have been used to extract synergistic properties from proteins and peptides. This review highlights the updates in the field of multicomponent self-assembly of proteins and peptides and summarizes various strategies, including covalent conjugation, ligand-receptor interactions, templated/directed assembly and non-specific co-assembly, for driving the self-assembly of multiple proteins and peptide-based building blocks into functional materials. In particular, we focus on peptide- or protein-containing multicomponent systems that, upon self-assembly, enable the emergence of new properties or phenomena. The ultimate goal of this review is to highlight the importance of multicomponent self-assembly in protein and peptide engineering, and to advocate its growth in the fields of materials science and nanotechnology.

Multicomponent Diffusion of Penetrant Mixtures in Rubbery Polymers: A Molecular Dynamics Study

NASA Astrophysics Data System (ADS)

Bringuier, Stefan; Varady, Mark; Knox, Craig; Cabalo, Jerry; Pearl, Thomas; Mantooth, Brent

The importance of understanding transport of chemical species across liquid-solid boundaries is of particular interest in the decontamination of harmful chemicals absorbed within polymeric materials. To characterize processes associated with liquid-phase extraction of absorbed species from polymers, it is necessary to determine an appropriate physical description of species transport in multicomponent systems. The Maxwell-Stefan (M-S) formulation is a rigorous description of mass transport in multicomponent solutions, in which, mutual diffusivities determine the degree of relative motion between interacting molecules in response to a chemical potential gradient. The work presented focuses on the determination of M-S diffusivities from molecular dynamics (MD) simulations of nerve agent O-ethyl S-[2(diisopropylamino)ethyl] methylphosphonothioate (VX), water, and methanol mixtures within a poly(dimethylsiloxane) matrix. We investigate the composition dependence of M-S diffusivities and compare the results to values predicted using empirical relations for binary and ternary mixtures. Finally, we highlight the pertinent differences in molecular mechanisms associated with species transport and employ non-equilibrium MD to probe transport across the mixture-polymer interface.

Application of a High-Throughput Analyzer in Evaluating Solid Adsorbents for Post-Combustion Carbon Capture via Multicomponent Adsorption of CO2, N-2, and H2O

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mason, JA; McDonald, TM; Bae, TH

Despite the large number of metal-organic frameworks that have been studied in the context of post-combustion carbon capture, adsorption equilibria of gas mixtures including CO2, N-2, and H2O, which are the three biggest components of the flue gas emanating from a coal- or natural gas-fired power plant, have never been reported. Here, we disclose the design and validation of a high-throughput multicomponent adsorption instrument that can measure equilibrium adsorption isotherms for mixtures of gases at conditions that are representative of an actual flue gas from a power plant. This instrument is used to study 15 different metal-organic frameworks, zeolites, mesoporousmore » silicas, and activated carbons representative of the broad range of solid adsorbents that have received attention for CO2 capture. While the multicomponent results presented in this work provide many interesting fundamental insights, only adsorbents functionalized with alkylamines are shown to have any significant CO2 capacity in the presence of N-2 and H2O at equilibrium partial pressures similar to those expected in a carbon capture process. Most significantly, the amine-appended metal organic framework mmen-Mg-2(dobpdc) (mmen = N,N'-dimethylethylenediamine, dobpdc (4-) = 4,4'-dioxido-3,3'-biphenyldicarboxylate) exhibits a record CO2 capacity of 4.2 +/- 0.2 mmol/g (16 wt %) at 0.1 bar and 40 degrees C in the presence of a high partial pressure of H2O.« less

Application of a high-throughput analyzer in evaluating solid adsorbents for post-combustion carbon capture via multicomponent adsorption of CO2, N2, and H2O.

PubMed

Mason, Jarad A; McDonald, Thomas M; Bae, Tae-Hyun; Bachman, Jonathan E; Sumida, Kenji; Dutton, Justin J; Kaye, Steven S; Long, Jeffrey R

2015-04-15

Despite the large number of metal-organic frameworks that have been studied in the context of post-combustion carbon capture, adsorption equilibria of gas mixtures including CO2, N2, and H2O, which are the three biggest components of the flue gas emanating from a coal- or natural gas-fired power plant, have never been reported. Here, we disclose the design and validation of a high-throughput multicomponent adsorption instrument that can measure equilibrium adsorption isotherms for mixtures of gases at conditions that are representative of an actual flue gas from a power plant. This instrument is used to study 15 different metal-organic frameworks, zeolites, mesoporous silicas, and activated carbons representative of the broad range of solid adsorbents that have received attention for CO2 capture. While the multicomponent results presented in this work provide many interesting fundamental insights, only adsorbents functionalized with alkylamines are shown to have any significant CO2 capacity in the presence of N2 and H2O at equilibrium partial pressures similar to those expected in a carbon capture process. Most significantly, the amine-appended metal organic framework mmen-Mg2(dobpdc) (mmen = N,N'-dimethylethylenediamine, dobpdc (4-) = 4,4'-dioxido-3,3'-biphenyldicarboxylate) exhibits a record CO2 capacity of 4.2 ± 0.2 mmol/g (16 wt %) at 0.1 bar and 40 °C in the presence of a high partial pressure of H2O.

Phase transitions in mixed gas hydrates: experimental observations versus calculated data.

PubMed

Schicks, Judith M; Naumann, Rudolf; Erzinger, Jörg; Hester, Keith C; Koh, Carolyn A; Sloan, E Dendy

2006-06-15

This paper presents the phase behavior of multicomponent gas hydrate systems formed from primarily methane with small amounts of ethane and propane. Experimental conditions were typically in a pressure range between 1 and 6 MPa, and the temperature range was between 260 and 290 K. These multicomponent systems have been investigated using a variety of techniques including microscopic observations, Raman spectroscopy, and X-ray diffraction. These techniques, used in combination, allowed for measurement of the hydrate structure and composition, while observing the morphology of the hydrate crystals measured. The hydrate formed immediately below the three-phase line (V-L --> V-L-H) and contained crystals that were both light and dark in appearance. The light crystals, which visually were a single solid phase, showed a spectroscopic indication for the presence of occluded free gas in the hydrate. In contrast, the dark crystals were measured to be structure II (sII) without the presence of these occluded phases. Along with hydrate measurements near the decomposition line, an unexpected transformation process was visually observed at P-T-conditions in the stability field of the hydrates. Larger crystallites transformed into a foamy solid upon cooling over this transition line (between 5 and 10 K below the decomposition temperature). Below the transition line, a mixture of sI and sII was detected. This is the first time that these multicomponent systems have been investigated at these pressure and temperature conditions using both visual and spectroscopic techniques. These techniques enabled us to observe and measure the unexpected transformation process showing coexistence of different gas hydrate phases.

The soda-ash roasting of chromite ore processing residue for the reclamation of chromium

NASA Astrophysics Data System (ADS)

Antony, M. P.; Tathavadkar, V. D.; Calvert, C. C.; Jha, A.

2001-12-01

Sodium chromate is produced via the soda-ash roasting of chromite ore with sodium carbonate. After the reaction, nearly 15 pct of the chromium oxide remains unreacted and ends up in the waste stream, for landfills. In recent years, the concern over environmental pollution from hexavalent chromium (Cr6+) from the waste residue has become a major problem for the chromium chemical industry. The main purpose of this investigation is to recover chromium oxide present in the waste residue as sodium chromate. Cr2O3 in the residue is distributed between the two spinel solid solutions, Mg(Al,Cr)2O4 and γ-Fe2O3. The residue from the sodium chromate production process was analyzed both physically and chemically. The compositions of the mineral phases were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). The influence of alkali addition on the overall reaction rate is examined. The kinetics of the chromium extraction reaction resulting from the residue of the soda-ash roasting process under an oxidizing atmosphere is also investigated. It is shown that the experimental results for the roasting reaction can be best described by the Ginstling and Brounshtein (GB) equation for diffusion-controlled kinetics. The apparent activation energy for the roasting reaction was calculated to be between 85 and 90 kJ·mol-1 in the temperature range 1223 to 1473 K. The kinetics of leaching of Cr3+ ions using the aqueous phase from the process residue is also studied by treating the waste into acid solutions with different concentrations.

Mineralogy and pore water chemistry of a boiler ash from a MSW fluidized-bed incinerator.

PubMed

Bodénan, F; Guyonnet, D; Piantone, P; Blanc, P

2010-07-01

This paper presents an investigation of the mineralogy and pore water chemistry of a boiler ash sampled from a municipal solid waste fluidized-bed incinerator, subject to 18 months of dynamic leaching in a large percolation column experiment. A particular focus is on the redox behaviour of Cr(VI) in relation to metal aluminium Al(0), as chromium may represent an environmental or health hazard. The leaching behaviour and interaction between Cr(VI) and Al(0) are interpreted on the basis of mineralogical evolutions observed over the 18-month period and of saturation indices calculated with the geochemical code PhreeqC and reviewed thermodynamic data. Results of mineralogical analyses show in particular the alteration of mineral phases during leaching (e.g. quartz and metal aluminium grains), while geochemical calculations suggest equilibria of percolating fluids with respect to specific mineral phases (e.g. monohydrocalcite and aluminium hydroxide). The combination of leaching data on a large scale and mineralogical analyses document the coupled leaching behaviour of aluminium and chromium, with chromium appearing in the pore fluids in its hexavalent and mobile state once metal aluminium is no longer available for chromium reduction. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Effect of Particle Morphology on Cold Spray Deposition of Chromium Carbide-Nickel Chromium Cermet Powders

NASA Astrophysics Data System (ADS)

Fernandez, Ruben; Jodoin, Bertrand

2017-08-01

Nickel chromium-chromium carbide coatings provide good corrosion and wear resistance at high temperatures, making them ideal for applications where a harsh environment and high temperatures are expected. Thermal spray processes are preferred as deposition technique of cermets, but the high process temperatures can lead to decarburization and reduction of the coatings properties. Cold spray uses lower temperatures preventing decarburization. Since the metallic phase remains solid, the feedstock powder morphology becomes crucial on the deposition behavior. Six commercially available powders were studied, varying in morphology and metal/ceramic ratios. The powders were categorized into 4 groups depending on their morphology. Spherical powders lead to substrate erosion due to their limited overall ductility. Porous agglomerated and sintered powders lead to severely cracked coatings. For dense agglomerated and sintered powders, the outcome depended on the initial metal/ceramic ratio: powders with 25 wt.% NiCr led to substrate erosion while 35 wt.% NiCr powders led to dense coatings. Finally, blended ceramic-metal mixtures also lead to dense coatings. All coatings obtained had lower ceramic content than the initial feedstock powders. Interrupted spray tests, combined with FEA, helped drawing conclusions on the deposition behavior to explain the obtained results.

Method of electrode fabrication for solid oxide electrochemical cells

DOEpatents

Jensen, R.R.

1990-11-20

A process for fabricating cermet electrodes for solid oxide electrochemical cells by sintering is disclosed. First, a porous metal electrode is fabricated on a solid oxide cell, such as a fuel cell by, for example, sintering, and is then infiltrated with a high volume fraction stabilized zirconia suspension. A second sintering step is used to sinter the infiltrated zirconia to a high density in order to more securely attach the electrode to the solid oxide electrolyte of the cell. High performance fuel electrodes can be obtained with this process. Further electrode performance enhancement may be achieved if stabilized zirconia doped with cerium oxide, chromium oxide, titanium oxide, and/or praseodymium oxide for electronic conduction is used. 5 figs.

Method of electrode fabrication for solid oxide electrochemical cells

DOEpatents

Jensen, Russell R.

1990-01-01

A process for fabricating cermet electrodes for solid oxide electrochemical cells by sintering is disclosed. First, a porous metal electrode is fabricated on a solid oxide cell, such as a fuel cell by, for example, sintering, and is then infiltrated with a high volume fraction stabilized zirconia suspension. A second sintering step is used to sinter the infiltrated zirconia to a high density in order to more securely attach the electrode to the solid oxide electrolyte of the cell. High performance fuel electrodes can be obtained with this process. Further electrode performance enhancement may be achieved if stabilized zirconia doped with cerium oxide, chromium oxide, titanium oxide, and/or praseodymium oxide for electronic conduction is used.

New alloys to conserve critical elements

NASA Technical Reports Server (NTRS)

Stephens, J. R.

1978-01-01

Based on availability of domestic reserves, chromium is one of the most critical elements within the U.S. metal industry. New alloys having reduced chromium contents which offer potential as substitutes for higher chromium containing alloys currently in use are being investigated. This paper focuses primarily on modified Type 304 stainless steels having one-third less chromium, but maintaining comparable oxidation and corrosion properties to that of type 304 stainless steel, the largest single use of chromium. Substitutes for chromium in these modified Type 304 stainless steel alloys include silicon and aluminum plus molybdenum.

Field-Integrated Studies of Long-Term Sustainability of Chromium Bioreduction at Hanford 100H Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, Philip E.

2006-06-01

The objectives of the project are to investigate coupled hydraulic, geochemical, and microbial conditions, and to determine the critical biogeochemical parameters necessary to maximize the extent of Cr(VI) bioreduction and minimize Cr(III) reoxidation in groundwater. Specific goals of the project are as follows: (1) Field testing and monitoring of Cr(VI) bioreduction in ground water and its transformation into insoluble species of Cr(III) at the Hanford 100H site, to develop the optimal strategy of water sampling for chemical, microbial, stable isotope analyses, and noninvasive geophysical monitoring; (2) Bench-scale flow and transport investigations using columns of undisturbed sediments to obtain diffusion andmore » kinetic parameters needed for the development of a numerical model, predictions of Cr(VI) bioreduction, and potential of Cr(III) reoxidation; and (3) Development of a multiphase, multi-component 3D reactive transport model and a code, TOUGHREACT-BIO, to predict coupled biogeochemical-hydrological processes associated with bioremediation, and to calibrate and validate the developed code based on the results of bench-scale and field-scale Cr(VI) biostimulation experiments in ground water at the Hanford Site.« less

Study on erosion behaviour of hybrid aluminium composite

NASA Astrophysics Data System (ADS)

Vishwas, D. K.; Chandrappa, C. N.; Venkatesh, Shreyas

2018-04-01

The origin of the light metals, as compared to other metals in this century, is noticeable and an exciting area of expansion for innovation. Light metals, are need of the day in engineering, among them application of aluminium and its alloys is enormous. we observe that these metals tend to have a progressive loss of metal from having contact surface with other metals. Erosion is one such wear process, where damage occurs by the repeated application of high localised stresses. Erosion due to impact of solid particle, is a significant problem. In the present work, the erosion behaviour of hybrid aluminium composite is studied. AL 6061 is used as the base alloy. AL 6061 alloy has excellent corrosion resistance but poor wear resistance. So, in order to have improved properties, it is reinforced with Tungsten Chromium Nickel powder in varied proportions by the method of stir casting. The results are compared with the as-cast Al-alloy to determine the improvement in mechanical properties. The tests were conducted in ASTM G76 setup, to determine solid particle erosion behaviour and the results of the hybrid composite were compared with that of as-cast AL 6061 alloy. It was evident that mass loss was maximum at 300 inclinations, which is a characteristic of ductile materials. It was observed that upon increasing the percentages of reinforcement (wt.%), the wear resistance of the hybrid composite increased significantly. It was also observed that the inclusion of tungsten-chromium-nickel powder increased the hardness of the hybrid composite significantly.

Preliminary Material Properties Handbook. Volume 2: SI Units

DTIC Science & Technology

2000-07-01

6-1 6.2 Iron- Chromium -Nickel-Base Alloys...iron, or chromium . In addition to strengthening of titanium by the alloying additions, alpha-beta alloys may be further strengthened by heat...6.3.3 6.3.4 6.3.5 6.4 6.5 6.5.1 Iron- Chromium -Nickel-Base Alloys Nickel-Base Alloys AEREX® 350 alloy HAYNES® 230® alloy HAYNES® HR-120® alloy Inconel

Tetravalent Chromium (Cr(4+)) as Laser-Active Ion for Tunable Solid-State Lasers

NASA Technical Reports Server (NTRS)

Seas, A.; Petricevic, V.; Alfano, Robert R.

1992-01-01

During 10/31/91 - 3/31/92, the following summarizes are major accomplishments: (1) numerical modeling of the four mirror astigmatically compensated, Z-fold cavity was performed; and (2) the simulation revealed several design parameters to be used for the construction of a femtosecond forsterite laser.

Raman studies on molecular and ionic forms in solid layers of nitrogen dioxide - Temperature and light induced effects

NASA Astrophysics Data System (ADS)

Givan, A.; Loewenschuss, A.

1990-12-01

Raman spectra of zero-pressure-formed N2O4 solid layers are reported. Sample composition is extremely dependent upon deposition conditions. For ordered and pure solid N2O4(D2h), produced by slow NO2 deposition, temperature cycling over the range in which the solid is stable shows no significant spectral changes and does not result in autoionization, as argued in a previous Raman study. Fast and low temperature deposited layers are amorphous and multicomponent, showing bands of disordered and isomeric molecular N2O4 and of ionic NO + NO3, nitrosonium nitrate. For nitrosonium nitrate, three solid modifications can be characterized spectroscopically. In the amorphous phase, a light induced, temperature dependent, reversible transition between molecular and ionic nitrogen tetroxide is observed below 150 K. The paths leading to nitrosonium nitrate formation are examined.

Production of Chromium Oxide from Turkish Chromite Concentrate Using Ethanol

NASA Astrophysics Data System (ADS)

Aktas, S.; Eyuboglu, C.; Morcali, M. H.; Özbey, S.; Sucuoglu, Y.

2015-05-01

In this study, the possibility of chromium extraction from Turkish chromite concentrate and the production of chromium oxide were investigated. For the conversion of chromium(III) into chromium(VI), NaOH was employed, as well as air with a rate of 20 L/min. The effects of the base amount, fusing temperature, and fusing time on the chromium conversion percentage were investigated in detail. The conversion kinetics of chromium(III) to chromium(VI) was also undertaken. Following the steps of dissolving the sodium chromate in water and filtering, aluminum hydroxide was precipitated by adjusting the pH level of the solution. The chromium(VI) solution was subsequently converted to Cr(III) by the combination of sulfuric acid and ethanol. Interestingly, it was observed that ethanol precipitated chromium as chromium(VI) at mildly acidic pH levels, although this effect is more pronounced for K2Cr2O7 than Na2Cr2O7. On the other hand, in the strongly acidic regime, ethanol acted as a reducing agent role in that chromium(VI) was converted into Cr(III) whereas ethanol itself was oxidized to carbon dioxide and water. Subsequently, chromium hydroxide was obtained by the help of sodium hydroxide and converted to chromium oxide by heating at 800 °C, as indicated in thermo gravimetric analysis (TGA).

Chromium Recycling in the United States in 1998

USGS Publications Warehouse

Papp, John F.

2001-01-01

The purpose of this report is to illustrate the extent to which chromium was recycled in the United States in 1998 and to identify chromium-recycling trends. The major use of chromium was in the metallurgical industry to make stainless steel; substantially less chromium was used in the refractory and chemical industries. In this study, the only chromium recycling reported was that which was a part of stainless steel scrap reuse. In 1998, 20 percent of the U.S. apparent consumption of chromium was secondary (from recycling); the remaining 80 percent was based on net chromium commodity imports and stock adjustments. Chromite ore was not mined in the United States in 1998. In 1998, 75,300 metric tons (t) of chromium contained in old scrap was consumed in the United States; it was valued at $66.4 million. Old scrap generated contained 132,000 t of chromium. The old scrap recycling efficiency was 87 percent, and the recycling rate was 20 percent. About 18,000 t of chromium in old scrap was unrecovered. New scrap consumed contained 28,600 t of chromium, which yielded a new-to-old-scrap ratio of 28:72. U.S. chromium-bearing stainless steel scrap net exports were valued at $154 million and were estimated to have contained 41,000 t of chromium.

Nonradiative relaxation and laser action in tunable solid state laser crystals

NASA Technical Reports Server (NTRS)

Petricevic, V.; Gayen, S. K.; Alfano, R. R.

1989-01-01

Room-temperature pulsed laser action was obtained in chromium-activated forsterite (Cr:Mg2SiO4) for both 532 and 1064 nm pumping. Free running laser emission in both cases is centered at 1235 nm and has a bandwidth of approximately 30 nm. Slope efficiency as high as 22 percent was measured. Using different sets of output mirrors and a single birefrigent plate as the intracavity wavelength selecting element tunability over the 1167 to 1268 nm spectral range was demonstrated. Continuous wave laser operation at room temperature was obtained for 1064 nm pumping from a CW Nd:YAG laser. The output power slope efficiency is 6.8 percent. The gain cross section is estimated to be 1.1 x 10 to the 19th sq cm. Spectroscopic studies suggest that the laser action is due to a center other than the trivalent chromium (Cr 3+), presumably the tetravalent chromium (Cr 4+) in a tetrahedrally coordinated site.

Two fold modified chitosan for enhanced adsorption of hexavalent chromium from simulated wastewater and industrial effluents.

PubMed

Kahu, S S; Shekhawat, A; Saravanan, D; Jugade, R M

2016-08-01

Ionic solid (Ethylhexadecyldimethylammoniumbromide) impregnated phosphated chitosan (ISPC) was synthesized and applied for enhanced adsorption of hexavalent chromium from industrial effluent. The compound obtained was extensively characterized using instrumental techniques like FT-IR, TGA-DTA, XRD, SEM, BET and EDX. ISPC showed high adsorption capacity of 266.67mg/g in accordance with Langmuir isotherm model at pH 3.0 due to the presence of multiple sites which contribute for ion pair and electrostatic interactions with Cr(VI) species. The sorption kinetics and thermodynamic studies revealed that adsorption of Cr(VI) followed pseudo-second-order kinetics with exothermic and spontaneous behaviour. Applicability of ISPC for higher sample volumes was discerned through column studies. The real chrome plating industry effluent was effectively treated with total chromium recovery of 94%. The used ISPC was regenerated simply by dilute ammonium hydroxide treatment and tested for ten adsorption-desorption cycles with marginal decrease in adsorption efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Comparison of Analytical and Numerical Methods for Modeling Dissolution and Other Reactions in Transport Limited Systems

NASA Astrophysics Data System (ADS)

Hochstetler, D. L.; Kitanidis, P. K.

2009-12-01

Modeling the transport of reactive species is a computationally demanding problem, especially in complex subsurface media, where it is crucial to improve understanding of geochemical processes and the fate of groundwater contaminants. In most of these systems, reactions are inherently fast and actual rates of transformations are limited by the slower physical transport mechanisms. There have been efforts to reformulate multi-component reactive transport problems into systems that are simpler and less demanding to solve. These reformulations include defining conservative species and decoupling of reactive transport equations so that fewer of them must be solved, leaving mostly conservative equations for transport [e.g., De Simoni et al., 2005; De Simoni et al., 2007; Kräutle and Knabner, 2007; Molins et al., 2004]. Complex and computationally cumbersome numerical codes used to solve such problems have also caused De Simoni et al. [2005] to develop more manageable analytical solutions. Furthermore, this work evaluates reaction rates and has reaffirmed that the mixing rate,▽TuD▽u, where u is a solute concentration and D is the dispersion tensor, as defined by Kitanidis [1994], is an important and sometimes dominant factor in determining reaction rates. Thus, mixing of solutions is often reaction-limiting. We will present results from analytical and computational modeling of multi-component reactive-transport problems. The results have applications to dissolution of solid boundaries (e.g., calcite), dissolution of non-aqueous phase liquids (NAPLs) in separate phases, and mixing of saltwater and freshwater (e.g. saltwater intrusion in coastal carbonate aquifers). We quantify reaction rates, compare numerical and analytical results, and analyze under what circumstances which approach is most effective for a given problem. References: DeSimoni, M., et al. (2005), A procedure for the solution of multicomponent reactive transport problems, Water Resources Research, 41(W11410). DeSimoni, M., et al. (2007), A mixing ratios-based formulation for multicomponent reactive transport, Water Resources Research, 43(W07419). Kitanidis, P. (1994), The Concept of the Dilution Index, Water Resources Research, 30(7), 2011-2026. Kräutle, S., and P. Knabner (2007), A reduction scheme for coupled multicomponent transport-reaction problems in porous media: Generalization to problems with heterogeneous equilibrium reactions Water Resources Research, 43. Molins, S., et al. (2004), A formulation for decoupling components in reactive transport porblems, Water Resources Research, 40, 13.

Preliminary Material Properties Handbook. Volume 1: English Units

DTIC Science & Technology

2000-07-01

6-1 6.2 Iron- Chromium -Nickel-Base Alloys...titanium but is stabilized to room temperature by sufficient quantities of beta stabilizing elements as vanadium, molybdenum, iron, or chromium . In...Designation 6.2 6.3 6.3.1 6.3.2 6.3.3 6.3.4 6.3.5 6.4 6.5 6.5.1 Iron- Chromium -Nickel-Base Alloys Nickel-Base Alloys AEREX® 350 alloy HAYNES® 230® alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, Y.M.; DiSante, C.J.; Lion, L.W.

Toxic trace metals have been implicated as a potential cause of recent flamingo kills at Lake Nakuru, Kenya. Chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) have accumulated in the lake sediments as a result of unregulated discharges and because this alkaline lake has no natural outlet. Lesser flamingos (Phoeniconaias minor) at Lake Nakuru feed predominantly on the cyanobacterium Spirulina platensis, and because of their filter-feeding mechanism, they are susceptible to exposure to particle-bound metals. Trace metal adsorption isotherms to lake sediments and S. platensis were obtained under simulated lake conditions, and a mathematical model was developed to predictmore » metal exposure via filter feeding based on predicted trace metal phase distribution. Metal adsorption to suspended solids followed the trend Pb {much_gt} Zn > Cr > Cu, and isotherms were linear up to 60 {micro}g/L. Adsorption to S. platensis cells followed the trend Pb {much_gt} Zn > Cu > Cr and fit Langmuir isotherms for Cr, Cu and Zn and a linear isotherm for Pb. Predicted phase distributions indicated that Cr and Pb in Lake Nakuru are predominantly associated with suspended solids, whereas Cu and Zn are distributed more evenly between the dissolved phase and particulate phases of both S. platensis and suspended solids. Based on established flamingo feeding rates and particle size selection, predicted Cr and Pb exposure occurs predominantly through ingestion of suspended solids, whereas Cu and Zn exposure occurs through ingestion of both suspended solids and S. platensis. For the lake conditions at the time of sampling, predicted ingestion rates based on measured metal concentrations in lake suspended solids were 0.71, 6.2, 0.81, and 13 mg/kg-d for Cr, Cu, Pb, and Zn, respectively.« less

Profiling planktonic biomass using element-specific, multicomponent nuclear magnetic resonance spectroscopy.

PubMed

Komatsu, Takanori; Kobayashi, Toshiya; Hatanaka, Minoru; Kikuchi, Jun

2015-06-02

Planktonic metabolism plays crucial roles in Earth's elemental cycles. Chemical speciation as well as elemental stoichiometry is important for advancing our understanding of planktonic roles in biogeochemical cycles. In this study, a multicomponent solid-state nuclear magnetic resonance (NMR) approach is proposed for chemical speciation of cellular components, using several advanced NMR techniques. Measurements by ssNMR were performed on (13)C and (15)N-labeled Euglena gracilis, a flagellated protist. 3D dipolar-assisted rotational resonance, double-cross-polarization (1)H-(13)C correlation spectroscopy, and (1)H-(13)C solid-state heteronuclear single quantum correlation spectroscopy successively allowed characterization of cellular components. These techniques were then applied to E. gracilis cultured in high and low ammonium media to demonstrate the power of this method for profiling and comparing cellular components. Cellular NMR spectra indicated that ammonium induced both paramylon degradation and amination. Arginine was stored as a nitrogen reserve and ammonium replaced by arginine catabolism via the arginine dihydrolase pathway. (15)N and (31)P cellular ssNMR indicated arginine and polyphosphate accumulation in E. gracilis, respectively. This chemical speciation technique will contribute to environmental research by providing detailed information on environmental chemical properties.

Multicomponent systems with cyclodextrins and hydrophilic polymers for the delivery of Efavirenz.

PubMed

Vieira, Alexandre Couto Carneiro; Ferreira Fontes, Danilo Augusto; Chaves, Luise Lopes; Alves, Lariza Darlene Santos; de Freitas Neto, José Lourenço; de La Roca Soares, Monica Felts; Soares-Sobrinho, Jose L; Rolim, Larissa Araújo; Rolim-Neto, Pedro José

2015-10-05

Efavirenz (EFZ) is one of the most used drugs in the treatment of AIDS and is the first antiretroviral choice. However, since it has low solubility, it does not exhibit suitable bioavailability, which interferes with its therapeutic action and is classified as a class II drug according Biopharmaceutical Classification System (low solubility and high permeability). Among several drug delivery systems, the multicomponent systems with cyclodextrins and hydrophilic polymers are a promising alternative for increasing the aqueous solubility of the drug. The present study aimed to develop and characterize in a ternary system of EFZ, MβCD and PVP K30. The results showed that the solid ternary system provided a large increase in the dissolution rate which was greater than 80% and was characterized by DSC, TG, XRD, FT-IR and SEM. The use of the ternary system (EFZ, MβCD and PVP K30 1%) proved to be a viable, effective and safe delivery of the drug. The addition of the hydrophilic polymer appeared to be suitable for the development of a solid oral pharmaceutical product, with possible industrial scale-up and with low concentration of CDs (cyclodextrins). Copyright © 2015 Elsevier Ltd. All rights reserved.

Joint Estimation of Time-Frequency Signature and DOA Based on STFD for Multicomponent Chirp Signals

PubMed Central

Zhao, Ziyue; Liu, Congfeng

2014-01-01

In the study of the joint estimation of time-frequency signature and direction of arrival (DOA) for multicomponent chirp signals, an estimation method based on spatial time-frequency distributions (STFDs) is proposed in this paper. Firstly, array signal model for multicomponent chirp signals is presented and then array processing is applied in time-frequency analysis to mitigate cross-terms. According to the results of the array processing, Hough transform is performed and the estimation of time-frequency signature is obtained. Subsequently, subspace method for DOA estimation based on STFD matrix is achieved. Simulation results demonstrate the validity of the proposed method. PMID:27382610

Joint Estimation of Time-Frequency Signature and DOA Based on STFD for Multicomponent Chirp Signals.

PubMed

Zhao, Ziyue; Liu, Congfeng

2014-01-01

In the study of the joint estimation of time-frequency signature and direction of arrival (DOA) for multicomponent chirp signals, an estimation method based on spatial time-frequency distributions (STFDs) is proposed in this paper. Firstly, array signal model for multicomponent chirp signals is presented and then array processing is applied in time-frequency analysis to mitigate cross-terms. According to the results of the array processing, Hough transform is performed and the estimation of time-frequency signature is obtained. Subsequently, subspace method for DOA estimation based on STFD matrix is achieved. Simulation results demonstrate the validity of the proposed method.

Combined biodegradation and ozonation for removal of tannins and dyes for the reduction of pollution loads.

PubMed

Kanagaraj, James; Mandal, Asit Baran

2012-01-01

Tannins and dyes pose major threat to the environment by generating huge pollution problem. Biodegradation of wattle extract, chrome tannin and dye compounds using suitable fungal culture namely Aspergillus niger, Penicillium sp. were carried out. In addition to these, ozone treatment was carried out to get higher degradation rate. The results were monitored by carrying out chemical oxygen demand (COD), total organic carbon (TOC), and UV-Vis analysis. The results showed that wattle extract (vegetable tannin) gave better biodegradation rate than dye and chromium compounds. Biodegradation plus ozone showed degradation rates of 92-95%, 94-95%, and 85-87% for the wattle extract, dyes, chromium compounds, respectively. UV-Vis showed that there were no peaks observed for biodegraded samples indicating better degradation rates as compared to the control samples. FT-IR spectra analysis suggested that the formation of flavanoid derivatives, chromic oxide and NH(2) compounds during degradation of wattle extract, chromium and dye compounds, respectively, at the peaks of 1,601-1,629 cm(-1), 1,647 cm(-1), and 1,610-1,680 cm(-1). The present investigation shows that combination of biodegradation with ozone is the effective method for the removal of dyes and tannins. The biodegradation of the said compounds in combination with ozonation showed better rate of degradation than by chemical methods. The combination of biodegradation with ozone helps to reduce pollution problems in terms of COD, TOC, total dissolved solids and total suspended solids.

Hexavalent Chromium Generation within Naturally Structured Soils and Sediments

DOE PAGES

Hausladen, Debra M.; Fendorf, Scott

2017-01-13

Chromium(VI) produced from the oxidation of indigenous Cr(III) minerals is increasingly being recognized as a threat to groundwater quality. A critical determinant of Cr(VI) generation within soils and sediments is the necessary interaction of two low-solubility phases$-$Cr(III) silicates or (hydr)oxides and Mn(III/IV) oxides—that lead to its production. Here in this paper, we investigate the potential for Cr(III) oxidation by Mn oxides within fixed solid matrices common to soils and sediments. Artificial aggregates were constructed from Cr(OH) 3- and Cr 0.25Fe 0.75(OH) 3-coated quartz grains and either mixed with synthetic birnessite or inoculated with the Mn(II)-oxidizing bacterium Leptothrix cholodnii. In aggregatesmore » simulating low organic carbon environments, we observe Cr(VI) concentrations within advecting solutes at levels more than twenty-times the California drinking water standard. Chromium(VI) production is highly dependent on Cr-mineral solubility; increasing Fe-substitution (x = 0 to x = 0.75) decreases the solubility of the solid and concomitantly decreases total Cr(VI) generation by 37%. In environments with high organic carbon, reducing conditions within aggregate cores (microbially) generate sufficient Fe(II) to suppress Cr(VI) efflux. Our results illustrate Cr(VI) generation from reaction with Mn oxides within structured media simulating soils and sediments and provide insight into how fluctuating hydrologic and redox conditions impact coupled processes controlling Cr and Mn cycling.« less

Hexavalent Chromium Generation within Naturally Structured Soils and Sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hausladen, Debra M.; Fendorf, Scott

Chromium(VI) produced from the oxidation of indigenous Cr(III) minerals is increasingly being recognized as a threat to groundwater quality. A critical determinant of Cr(VI) generation within soils and sediments is the necessary interaction of two low-solubility phases$-$Cr(III) silicates or (hydr)oxides and Mn(III/IV) oxides—that lead to its production. Here in this paper, we investigate the potential for Cr(III) oxidation by Mn oxides within fixed solid matrices common to soils and sediments. Artificial aggregates were constructed from Cr(OH) 3- and Cr 0.25Fe 0.75(OH) 3-coated quartz grains and either mixed with synthetic birnessite or inoculated with the Mn(II)-oxidizing bacterium Leptothrix cholodnii. In aggregatesmore » simulating low organic carbon environments, we observe Cr(VI) concentrations within advecting solutes at levels more than twenty-times the California drinking water standard. Chromium(VI) production is highly dependent on Cr-mineral solubility; increasing Fe-substitution (x = 0 to x = 0.75) decreases the solubility of the solid and concomitantly decreases total Cr(VI) generation by 37%. In environments with high organic carbon, reducing conditions within aggregate cores (microbially) generate sufficient Fe(II) to suppress Cr(VI) efflux. Our results illustrate Cr(VI) generation from reaction with Mn oxides within structured media simulating soils and sediments and provide insight into how fluctuating hydrologic and redox conditions impact coupled processes controlling Cr and Mn cycling.« less

Nonstationary heat and mass transfer in the multilayer building construction with ventilation channels

NASA Astrophysics Data System (ADS)

Kharkov, N. S.

2017-11-01

Results of numerical modeling of the coupled nonstationary heat and mass transfer problem under conditions of a convective flow in facade system of a three-layer concrete panel for two different constructions (with ventilation channels and without) are presented. The positive effect of ventilation channels on the energy and humidity regime over a period of 12 months is shown. Used new method of replacement a solid zone (requiring specification of porosity and material structure, what complicates process of convergence of the solution) on quasi-solid in form of a multicomponent mixture (with restrictions on convection and mass fractions).

Chromium-removal processes during groundwater remediation by a zerovalent iron permeable reactive barrier.

PubMed

Wilkin, Richard T; Su, Chunming; Ford, Robert G; Paul, Cynthia J

2005-06-15

Solid-phase associations of chromium were examined in core materials collected from a full-scale, zerovalent iron permeable reactive barrier (PRB) at the U.S. Coast Guard Support Center located near Elizabeth City, NC. The PRB was installed in 1996 to treat groundwater contaminated with hexavalent chromium. After eight years of operation, the PRB remains effective at reducing concentrations of Cr from average values >1500 microg L(-1) in groundwater hydraulically upgradient of the PRB to values <1 microg L(-1) in groundwater within and hydraulically downgradient of the PRB. Chromium removal from groundwater occurs at the leading edge of the PRB and also within the aquifer immediately upgradient of the PRB. These regions also witness the greatest amount of secondary mineral formation due to steep geochemical gradients that result from the corrosion of zerovalent iron. X-ray absorption near-edge structure (XANES) spectroscopy indicated that chromium is predominantly in the trivalent oxidation state, confirming that reductive processes are responsible for Cr sequestration. XANES spectra and microscopy results suggest that Cr is, in part, associated with iron sulfide grains formed as a consequence of microbially mediated sulfate reduction in and around the PRB. Results of this study provide evidence that secondary iron-bearing mineral products may enhance the capacity of zerovalent iron systems to remediate Cr in groundwater, either through redox reactions at the mineral-water interface or by the release of Fe(II) to solution via mineral dissolution and/or metal corrosion.

Multi-component intrinsic brain activities as a safe, alternative to cortical stimulation for sensori-motor mapping in neurosurgery.

PubMed

Neshige, Shuichiro; Matsuhashi, Masao; Kobayashi, Katsuya; Sakurai, Takeyo; Shimotake, Akihiro; Hitomi, Takefumi; Kikuchi, Takayuki; Yoshida, Kazumichi; Kunieda, Takeharu; Matsumoto, Riki; Takahashi, Ryosuke; Miyamoto, Susumu; Maruyama, Hirofumi; Matsumoto, Masayasu; Ikeda, Akio

2018-06-18

To assess the feasibility of multi-component electrocorticography (ECoG)-based mapping using "wide-spectrum, intrinsic-brain activities" for identifying the primary sensori-motor area (S1-M1) by comparing that using electrical cortical stimulation (ECS). We evaluated 14 epilepsy patients with 1514 subdural electrodes implantation covering the perirolandic cortices at Kyoto University Hospital between 2011 and 2016. We performed multi-component, ECoG-based mapping (band-pass filter, 0.016-300/600 Hz) involving combined analyses of the single components: movement-related cortical potential (<0.5-1 Hz), event-related synchronization (76-200 Hz), and event-related de-synchronization (8-24 Hz) to identify the S1-M1. The feasibility of multi-component mapping was assessed through comparisons with single-component mapping and ECS. Among 54 functional areas evaluation, ECoG-based maps showed significantly higher rate of localization concordances with ECS maps when the three single-component maps were consistent than when those were inconsistent with each other (p < 0.001 in motor, and p = 0.02 in sensory mappings). Multi-component mapping revealed high sensitivity (89-90%) and specificity (94-97%) as compared with ECS. Wide-spectrum, multi-component ECoG-based mapping is feasible, having high sensitivity/specificity relative to ECS. This safe (non-stimulus) mapping strategy, alternative to ECS, would allow clinicians to rule in/out the possibility of brain function prior to resection surgery. Copyright © 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Interdiffusion in Ternary Magnesium Solid Solutions of Aluminum and Zinc

DOE PAGES

Kammerer, Catherine; Kulkarni, Nagraj S; Warmack, Robert J Bruce; ...

2016-01-11

Al and Zn are two of the most common alloying elements in commercial Mg alloys, which can improve the physical properties through solid solution strengthening and precipitation hardening. Diffusion plays a key role in the kinetics of these and other microstructural design relevant to Mg-alloy development. However, there is a lack of multicomponent diffusion data available for Mg alloys. Through solid-to-solid diffusion couples, diffusional interactions of Al and Zn in ternary Mg solid-solution at 400° and 450 °C were examined by an extension of the Boltzmann-Matano analysis based on Onsager s formalism. Concentration profiles of Mg-Al-Zn ternary alloys were determinedmore » by electron probe microanalysis, and analyzed to determine the ternary interdiffusion coefficients as a function of composition. Zn was determined to interdiffuse the fastest, followed by Mg and Al. Appreciable diffusional interactions among Mg, Al, and Zn were observed by variations in sign and magnitude of cross interdiffusion coefficients. In particular, Zn was found to significantly influence the interdiffusion of Mg and Al significantly: the and ternary cross interdiffusion coefficients were both negative, and large in magnitude, in comparison to and , respectively. Al and Mg were observed influence the interdiffusion of Mg and Al, respectively, with positive and interdiffusion coefficients, but their influence on the Zn interdiffusion was negligible.« less

Preliminary Material Properties Handbook, English Units

DTIC Science & Technology

1999-12-01

References 5-17 Chapter 6. Heat-Resistant Alloys 6.1 General 6-1 6.2 Iron- Chromium -Nickel-Base Alloys 6-3 6.3 Nickel-Base Alloys 6-3 6.4...elements as vanadium, molybdenum, iron, or chromium . In addition to strengthening of titanium by the alloying additions, alpha-beta alloys may be...alloys are arbitrarily defined as iron alloys richer in alloy content than the 18 percent chromium , 8 percent nickel types, or as alloys with a base

Chromium liquid waste inertization in an inorganic alkali activated matrix: leaching and NMR multinuclear approach.

PubMed

Ponzoni, Chiara; Lancellotti, Isabella; Barbieri, Luisa; Spinella, Alberto; Saladino, Maria Luisa; Martino, Delia Chillura; Caponetti, Eugenio; Armetta, Francesco; Leonelli, Cristina

2015-04-09

A class of inorganic binders, also known as geopolymers, can be obtained by alkali activation of aluminosilicate powders at room temperature. The process is affected by many parameters (curing time, curing temperature, relative humidity etc.) and leads to a resistant matrix usable for inertization of hazardous waste. In this study an industrial liquid waste containing a high amount of chromium (≈ 2.3 wt%) in the form of metalorganic salts is inertized into a metakaolin based geopolymer matrix. One of the innovative aspects is the exploitation of the water contained in the waste for the geopolymerization process. This avoided any drying treatment, a common step in the management of liquid hazardous waste. The evolution of the process--from the precursor dissolution to the final geopolymer matrix hardening--of different geopolymers containing a waste amount ranging from 3 to 20%wt and their capability to inertize chromium cations were studied by: i) the leaching tests, according to the EN 12,457 regulation, at different curing times (15, 28, 90 and 540 days) monitoring releases of chromium ions (Cr(III) and Cr(VI)) and the cations constituting the aluminosilicate matrix (Na, Si, Al); ii) the humidity variation for different curing times (15 and 540 days); iii) SEM characterization at different curing times (28 and 540 days); iv) the trend of the solution conductivity and pH during the leaching test; v) the characterization of the short-range ordering in terms of TOT bonds (where T is Al or Si) by (29)Si and (27)Al solid state magic-angle spinning nuclear magnetic resonance (ss MAS NMR) for geopolymers containing high amounts of waste (10-20%wt). The results show the formation of a stable matrix after only 15 days independently on the waste amount introduced; the longer curing times increase the matrices stabilities and their ability to immobilize chromium cations. The maximum amount of waste that can be inertized is around 10 wt% after a curing time of 28 days. Copyright © 2014 Elsevier B.V. All rights reserved.

Method for fabricating wrought components for high-temperature gas-cooled reactors and product

DOEpatents

Thompson, Larry D.; Johnson, Jr., William R.

1985-01-01

A method and alloys for fabricating wrought components of a high-temperature gas-cooled reactor are disclosed. These wrought, nickel-based alloys, which exhibit strength and excellent resistance to carburization at elevated temperatures, include aluminum and titanium in amounts and ratios to promote the growth of carburization resistant films while preserving the wrought character of the alloys. These alloys also include substantial amounts of molybdenum and/or tungsten as solid-solution strengtheners. Chromium may be included in concentrations less than 10% to assist in fabrication. Minor amounts of carbon and one or more carbide-forming metals also contribute to high-temperature strength.

Modeling of gun barrel surface erosion: Historic perspective

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buckingham, A.C.

1996-08-01

Results and interpretations of numerical simulations of some dominant processes influencing gun barrel propellant combustion and flow-induced erosion are presented. Results include modeled influences of erosion reduction techniques such as solid additives, vapor phase chemical modifications, and alteration of surface solid composition through use of thin coatings. Precedents and historical perspective are provided with predictions from traditional interior ballistics compared to computer simulations. Accelerating reactive combustion flow, multiphase and multicomponent transport, flow-to-surface thermal/momentum/phase change/gas-surface chemical exchanges, surface and micro-depth subsurface heating/stress/composition evolution and their roles in inducing surface cracking, spall, ablation, melting, and vaporization are considered. Recognition is given tomore » cyclic effects of previous firing history on material preconditioning. Current perspective and outlook for future are based on results of a US Army-LLNL erosion research program covering 7 y in late 1970s. This is supplemented by more recent research on hypervelocity electromagnetic projectile launchers.« less

40 CFR Appendix III to Part 265 - EPA Interim Primary Drinking Water Standards

Code of Federal Regulations, 2011 CFR

2011-07-01

...) SOLID WASTES (CONTINUED) INTERIM STATUS STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT... 40 Protection of Environment 26 2011-07-01 2011-07-01 false EPA Interim Primary Drinking Water... Water Standards Parameter Maximum level (mg/l) Arsenic 0.05 Barium 1.0 Cadmium 0.01 Chromium 0.05...

40 CFR Appendix III to Part 265 - EPA Interim Primary Drinking Water Standards

Code of Federal Regulations, 2010 CFR

2010-07-01

...) SOLID WASTES (CONTINUED) INTERIM STATUS STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT... 40 Protection of Environment 25 2010-07-01 2010-07-01 false EPA Interim Primary Drinking Water... Water Standards Parameter Maximum level (mg/l) Arsenic 0.05 Barium 1.0 Cadmium 0.01 Chromium 0.05...

Agency for Healthcare Research and Quality Evidence-based Practice Center methods for systematically reviewing complex multicomponent health care interventions.

PubMed

Guise, Jeanne-Marie; Chang, Christine; Viswanathan, Meera; Glick, Susan; Treadwell, Jonathan; Umscheid, Craig A; Whitlock, Evelyn; Fu, Rongwei; Berliner, Elise; Paynter, Robin; Anderson, Johanna; Motu'apuaka, Pua; Trikalinos, Tom

2014-11-01

The purpose of this Agency for Healthcare Research and Quality Evidence-based Practice Center methods white paper was to outline approaches to conducting systematic reviews of complex multicomponent health care interventions. We performed a literature scan and conducted semistructured interviews with international experts who conduct research or systematic reviews of complex multicomponent interventions (CMCIs) or organizational leaders who implement CMCIs in health care. Challenges identified include lack of consistent terminology for such interventions (eg, complex, multicomponent, multidimensional, multifactorial); a wide range of approaches used to frame the review, from grouping interventions by common features to using more theoretical approaches; decisions regarding whether and how to quantitatively analyze the interventions, from holistic to individual component analytic approaches; and incomplete and inconsistent reporting of elements critical to understanding the success and impact of multicomponent interventions, such as methods used for implementation the context in which interventions are implemented. We provide a framework for the spectrum of conceptual and analytic approaches to synthesizing studies of multicomponent interventions and an initial list of critical reporting elements for such studies. This information is intended to help systematic reviewers understand the options and tradeoffs available for such reviews. Copyright © 2014 Elsevier Inc. All rights reserved.

Method of bonding a conductive layer on an electrode of an electrochemical cell

DOEpatents

Bowker, J.C.; Singh, P.

1989-08-29

A dense, electronically conductive interconnection layer is bonded onto a porous, tubular, electronically conductive air electrode structure, optionally supported by a ceramic support, by (A) providing an air electrode surface, (B) forming on a selected portion of the electrode surface, without the use of pressure, particles of LaCrO[sub 3] doped with an element selected from the group consisting of Sr, Mg, Ca, Ba, Co, and mixtures thereof, where the particles have a deposit on their surface comprising calcium oxide and chromium oxide; (C) heating the particles with the oxide surface deposit in an oxidizing atmosphere at from 1,300 C to 1,550 C, without the application of pressure, to provide a dense, sintered, interconnection material bonded to the air electrode, where calcium and chromium from the surface deposit are incorporated into the structure of the LaCrO[sub 3]. A solid electrolyte layer can be applied to the uncovered portion of the air electrode, and a fuel electrode can be applied to the solid electrolyte, to provide an electrochemical cell. 4 figs.

Method of bonding a conductive layer on an electrode of an electrochemical cell

DOEpatents

Bowker, Jeffrey C.; Singh, Prabhakar

1989-01-01

A dense, electronically conductive interconnection layer 26 is bonded onto a porous, tubular, electronically conductive air electrode structure 16, optionally supported by a ceramic support 22, by (A) providing an air electrode surface, (B) forming on a selected portion of the electrode surface 24, without the use of pressure, particles of LaCrO.sub.3 doped with an element selected from the group consisting of Sr, Mg, Ca, Ba, Co, and mixtures thereof, where the particles have a deposit on their surface comprising calcium oxide and chromium oxide; (C) heating the particles with the oxide surface deposit in an oxidizing atmosphere at from 1,300.degree. C. to 1,550.degree. C., without the application of pressure, to provide a dense, sintered, interconnection material 26 bonded to the air electrode 16, where calcium and chromium from the surface deposit are incorporated into the structure of the LaCrO.sub.3. A solid electrolyte layer 18 can be applied to the uncovered portion of the air electrode, and a fuel electrode 20 can be applied to the solid electrolyte, to provide an electrochemical cell 10.

Chromium and Ruthenium-Doped Zinc Oxide Thin Films for Propane Sensing Applications

PubMed Central

Gómez-Pozos, Heberto; González-Vidal, José Luis; Torres, Gonzalo Alberto; Rodríguez-Baez, Jorge; Maldonado, Arturo; de la Luz Olvera, María; Acosta, Dwight Roberto; Avendaño-Alejo, Maximino; Castañeda, Luis

2013-01-01

Chromium and ruthenium-doped zinc oxide (ZnO:Cr) and (ZnO:Ru) thin solid films were deposited on soda-lime glass substrates by the sol-gel dip-coating method. A 0.6 M solution of zinc acetate dihydrate dissolved in 2-methoxyethanol and monoethanolamine was used as basic solution. Chromium (III) acetylacetonate and Ruthenium (III) trichloride were used as doping sources. The Ru incorporation and its distribution profile into the films were proved by the SIMS technique. The morphology and structure of the films were studied by SEM microscopy and X-ray diffraction measurements, respectively. The SEM images show porous surfaces covered by small grains with different grain size, depending on the doping element, and the immersions number into the doping solutions. The sensing properties of ZnO:Cr and ZnO:Ru films in a propane (C3H8) atmosphere, as a function of the immersions number in the doping solution, have been studied in the present work. The highest sensitivity values were obtained for films doped from five immersions, 5.8 and 900, for ZnO:Cr and ZnO:Ru films, respectively. In order to evidence the catalytic effect of the chromium (Cr) and ruthenium (Ru), the sensing characteristics of undoped ZnO films are reported as well. PMID:23482091

Recirculating Industrial Air: The Impact on Air Compliance and Workers; Safety Case Study: Hill Air Force Base C-130 Painting Operations.

DTIC Science & Technology

1998-06-29

chromium are Cr° (metal), Cr3+ and Cr6+. The trivalent chromium (Cr3+) and hexavalent chromium (Cr6+) are the most biologically significant. Cr + is...REFERENCES Agency for Toxic Substances and Disease Registry (ATSDR). "Case Studies in Environmental Medicine: Chromium Toxicity," U.S. Department...Wilson B. M. ’The Fate of Hexavalent Chromium in the Atmosphere," Research Triangle Institute RTI/3 798/00- 01F (October 1988). Hughes, S., Ayer, J

Improved Cook-off Modeling of Multi-component Cast Explosives

NASA Astrophysics Data System (ADS)

Nichols, Albert

2017-06-01

In order to understand the hazards associated with energetic materials, it is important to understand their behavior in adverse thermal environments. These processes have been relatively well understood for solid explosives, however, the same cannot be said for multi-component melt-cast explosives. Here we describe the continued development of ALE3D, a coupled thermal/chemical/mechanical code, to improve its description of fluid explosives. The improved physics models include: 1) Chemical potential driven species segregation. This model allows us to model the complex flow fields associated with the melting and decomposing Comp-B, where the denser RDX tends to settle and the decomposing gasses rise, 2) Automatically scaled stream-wise diffusion model for thermal, species, and momentum diffusion. These models add sufficient numerical diffusion in the direction of flow to maintain numerical stability when the system is under resolved, as occurs for large systems. And 3) a slurry viscosity model, required to properly define the flow characteristics of the multi-component fluidized system. These models will be demonstrated on a simple Comp-B system. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

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

EPA Science Inventory

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...

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

NASA Astrophysics Data System (ADS)

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

2018-03-01

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

Air Force Successes and Challenges in Cr(VI) Elimination

DTIC Science & Technology

2011-05-10

ion vapor deposited Al, and Cd coatings 2. Use trivalent chromium [Cr(III)] conversion coating (CC) on Dipsol IZ- C17+ zinc-nickel (Zn-Ni) coating...interested in results Anodized T-38 aileron levers 10 Chromium -Free Conversion Coatings  Identify and evaluate chromium -free conversion coatings (CFCCs...the chromium -based conversion coating for treatment of aluminum alloys at OC-ALC • Conduct technology assessment to identify suitable Cr-free

Hydrodynamic Models for Multicomponent Plasmas with Collisional-Radiative Kinetics

DTIC Science & Technology

2014-12-01

16, 17]. The plasma, typically created by electric discharges , can deposit heat locally in the vicinity the flame, which quickly raises the gas...the corona layer of laser produced plasmas (LPP). Secondly, the self-consistent coupling of the plasma with the field gives rise to particle...excited species and reaction radicals; 7 n ncr solid transport layer (overdense) corona layer (underdense) temperature density shock wave ablation

Semi-solid processing of high-chromium tool steel to obtain microstructures without carbide network

NASA Astrophysics Data System (ADS)

Jirková, H.; Aišman, D.; Rubešová, K.; Opatová, K.; Mašek, B.

2017-02-01

Treatment of high-alloy tool steels that involves transition to the semi-solid state can transform the sharp-edged primary carbides which usually form during solidification. These carbides severely impair toughness and are virtually impossible to eliminate by conventional treatment routes. Upon classical semi-solid processing which dissolves these carbides, the resulting microstructure consists of polyhedral and super-saturated austenite embedded in lamellar austenite-carbide network. This type of microstructure reflects in the mechanical properties, predominantly in material behaviour under tensile loading. Such a network, however, can be removed by appropriate thermomechanical treatment. In the present experiment, various procedures involving heating to the semi-solid state were tested on X210Cr12 tool steel. The feedstock was heated to the temperature range of 1220 - 1280 °C. The heating was followed by procedures involving either water quenching to the forming temperature, room temperature or temperature from the range from 500 °C to 1000 °C followed by reheating to the forming temperature. It was found that the development of the lamellar network strongly depends on the temperature of heating to semi-solid state. Thermomechanical treatment produced microstructures in which the matrix consisted of a mixture of polyhedral austenite grains and the M-A constituent. In addition, the initial lamellar eutectic network was partially or even completely melted and substituted with a mixture of very fine recrystallized austenite grains and precipitates of chromium carbides. Some fine M7C3 carbides were present in the austenitic-martensitic matrix as well. When appropriate processing parameters were chosen, very good mechanical properties were obtained, among them a hardness of 860 HV10.

Multinary alloy electrodes for solid state batteries I. A phase diagram approach for the selection and storage properties determination of candidate electrode materials

NASA Astrophysics Data System (ADS)

Anani, A.; Huggins, R. A.

The desire to produce high specific energy rechargeable batteries has led to the investigation of ternary alloy systems for use as negative electrode components in lithium-based cells. The addition of a third component to a binary alloy electrode could result in a significant change in the thermodynamic and/or kinetic behavior of the electrode material, depending on the relevant phase diagram and the crystal structures of the phases present. The influence of ternary phase diagram characteristics upon the thermodynamic properties and specific energies of multi-component electrodes is discussed with lithiumsilicon-based systems as an illustration. It is shown that the electrode potentials (and thus specific energies of the ensuing cell) as well as the theoretical lithium capacities of electrodes based on these ternary alloy modifications can be significantly increased with respect to their present day binary counterpart.

Roles of the State Asthma Program in Implementing Multicomponent, School-Based Asthma Interventions

ERIC Educational Resources Information Center

Hester, Laura L.; Wilce, Maureen A.; Gill, Sarah A.; Disler, Sheri L.; Collins, Pamela; Crawford, Gregory

2013-01-01

Background: Asthma is a leading chronic childhood disease in the United States and a major contributor to school absenteeism. Evidence suggests that multicomponent, school-based asthma interventions are a strategic way to address asthma among school-aged children. The Centers for Disease Control and Prevention (CDC) encourages the 36 health…

Using Data to Individualize a Multicomponent, Technology-Based Self-Monitoring Intervention

ERIC Educational Resources Information Center

Bruhn, Allison Leigh; Vogelgesang, Kari; Fernando, Josephine; Lugo, Wilbeth

2016-01-01

Technology in schools is abundant as is the call for evidence-based interventions for students who need additional support to be successful. One promising use of technology is for self-monitoring interventions aimed at improving classroom behavior. In this study, two middle school students with disabilities used a multicomponent, self-monitoring…

Using a Multicomponent Function-Based Intervention to Support Students with Attention Deficit Hyperactivity Disorder

ERIC Educational Resources Information Center

Cho, Su-Je; Blair, Kwang-Sun Cho

2017-01-01

The current study evaluated the effects of a multicomponent function-based intervention on students with other health impairment (OHI) for attention deficit hyperactivity disorder (ADHD) in a private special education school. The focus of the intervention was to prevent problem behaviors and to increase academic engagement by modifying classroom…

Early Reading Intervention by Means of a Multicomponent Reading Game

ERIC Educational Resources Information Center

van de Ven, M.; de Leeuw, L.; van Weerdenburg, M.; Steenbeek-Planting, E. G.

2017-01-01

This study examined the effects of an intervention with a multicomponent reading game on the development of reading skills in 60 Dutch primary school children with special educational needs. The game contains evidence-based reading exercises and is based on principles of applied gaming. Using a multiple baseline approach, we tested children's…

Cascade multicomponent synthesis of indoles, pyrazoles, and pyridazinones by functionalization of alkenes.

PubMed

Matcha, Kiran; Antonchick, Andrey P

2014-10-27

The development of multicomponent reactions for indole synthesis is demanding and has hardly been explored. The present study describes the development of a novel multicomponent, cascade approach for indole synthesis. Various substituted indole derivatives were obtained from simple reagents, such as unfunctionalized alkenes, diazonium salts, and sodium triflinate, by using an established straightforward and regioselective method. The method is based on the radical trifluoromethylation of alkenes as an entry into Fischer indole synthesis. Besides indole synthesis, the application of the multicomponent cascade reaction to the synthesis of pyrazoles and pyridazinones is described. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanopatterning of Surfaces with Monometallic and Heterobimetallic 1D Coordination Polymers: A Molecular Tectonics Approach at the Solid/Liquid Interface.

PubMed

El Garah, Mohamed; Marets, Nicolas; Mauro, Matteo; Aliprandi, Alessandro; Bonacchi, Sara; De Cola, Luisa; Ciesielski, Artur; Bulach, Véronique; Hosseini, Mir Wais; Samorì, Paolo

2015-07-08

The self-assembly of multiple molecular components into complex supramolecular architectures is ubiquitous in nature and constitutes one of the most powerful strategies to fabricate multifunctional nanomaterials making use of the bottom-up approach. When spatial confinement in two dimensions on a solid substrate is employed, this approach can be exploited to generate periodically ordered structures from suitably designed molecular tectons. In this study we demonstrate that physisorbed directional periodic arrays of monometallic or heterobimetallic coordination polymers can be generated on a highly oriented pyrolitic graphite surface by combinations of a suitably designed directional organic tecton or metallatecton based on a porphyrin or nickel(II) metalloporphyrin backbone bearing both a pyridyl unit and a terpyridyl unit acting as coordinating sites for CoCl2. The periodic architectures were visualized at the solid/liquid interface with a submolecular resolution by scanning tunneling microscopy and corroborated by combined density functional and time-dependent density functional theory calculations. The capacity to nanopattern the surface for the first time with two distinct metallic centers exhibiting different electronic and optical properties is a key step toward the bottom-up construction of robust multicomponent and, thus, multifunctional molecular nanostructures and nanodevices.

Full Eulerian simulations of biconcave neo-Hookean particles in a Poiseuille flow

NASA Astrophysics Data System (ADS)

Sugiyama, Kazuyasu; , Satoshi, II; Takeuchi, Shintaro; Takagi, Shu; Matsumoto, Yoichiro

2010-03-01

For a given initial configuration of a multi-component geometry represented by voxel-based data on a fixed Cartesian mesh, a full Eulerian finite difference method facilitates solution of dynamic interaction problems between Newtonian fluid and hyperelastic material. The solid volume fraction, and the left Cauchy-Green deformation tensor are temporally updated on the Eulerian frame, respectively, to distinguish the fluid and solid phases, and to describe the solid deformation. The simulation method is applied to two- and three-dimensional motions of two biconcave neo-Hookean particles in a Poiseuille flow. Similar to the numerical study on the red blood cell motion in a circular pipe (Gong et al. in J Biomech Eng 131:074504, 2009), in which Skalak’s constitutive laws of the membrane are considered, the deformation, the relative position and orientation of a pair of particles are strongly dependent upon the initial configuration. The increase in the apparent viscosity is dependent upon the developed arrangement of the particles. The present Eulerian approach is demonstrated that it has the potential to be easily extended to larger system problems involving a large number of particles of complicated geometries.

Utilization of oriented crystal growth for screening of aromatic carboxylic acids cocrystallization with urea

NASA Astrophysics Data System (ADS)

Przybyłek, Maciej; Ziółkowska, Dorota; Kobierski, Mirosław; Mroczyńska, Karina; Cysewski, Piotr

2016-01-01

The possibility of molecular complex formation in the solid state of urea with benzoic acid analogues was measured directly on the crystallite films deposited on the glass surface using powder X-ray diffractometry (PXRD). Obtained solid mixtures were also analyzed using Fourier transform infrared spectroscopy (FTIR). The simple droplet evaporation method was found to be efficient, robust, fast and cost-preserving approach for first stage cocrystal screening. Additionally, the application of orientation effect to cocrystal screening simplifies the analysis due to damping of majority of diffraction signals coming from coformers. During validation phase the proposed approach successfully reproduced both positive cases of cocrystallization (urea:salicylic acid and urea:4-hydroxy benzoic acid) as well as pairs of co-formers immiscible in the solid state (urea:benzoic acid and urea:acetylsalicylic acids). Based on validated approach new cocrystals of urea were identified in complexes with 3-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid and 3,5-dihydroxybenzoic acid. In all cases formation of multicomponent crystal phase was confirmed by the appearance of new reflexes on the diffraction patterns and FTIR absorption band shifts of O-H and N-H groups.

CCA-treated wood disposed in landfills and life-cycle trade-offs with waste-to-energy and MSW landfill disposal.

PubMed

Jambeck, Jenna; Weitz, Keith; Solo-Gabriele, Helena; Townsend, Timothy; Thorneloe, Susan

2007-01-01

Chromated copper arsenate (CCA)-treated wood is a preservative treated wood construction product that grew in use in the 1970s for both residential and industrial applications. Although some countries have banned the use of the product for some applications, others have not, and the product continues to enter the waste stream from construction, demolition and remodeling projects. CCA-treated wood as a solid waste is managed in various ways throughout the world. In the US, CCA-treated wood is disposed primarily within landfills; however some of the wood is combusted in waste-to-energy (WTE) facilities. In other countries, the predominant disposal option for wood, sometimes including CCA-treated wood, is combustion for the production of energy. This paper presents an estimate of the quantity of CCA-treated wood entering the disposal stream in the US, as well as an examination of the trade-offs between landfilling and WTE combustion of CCA-treated wood through a life-cycle assessment and decision support tool (MSW DST). Based upon production statistics, the estimated life span and the phaseout of CCA-treated wood, recent disposal projections estimate the peak US disposal rate to occur in 2008, at 9.7 million m(3). CCA-treated wood, when disposed with construction and demolition (C&D) debris and municipal solid waste (MSW), has been found to increase arsenic and chromium concentrations in leachate. For this reason, and because MSW landfills are lined, MSW landfills have been recommended as a preferred disposal option over unlined C&D debris landfills. Between landfilling and WTE for the same mass of CCA-treated wood, WTE is more expensive (nearly twice the cost), but when operated in accordance with US Environmental Protection Agency (US EPA) regulations, it produces energy and does not emit fossil carbon emissions. If the wood is managed via WTE, less landfill area is required, which could be an influential trade-off in some countries. Although metals are concentrated in the ash in the WTE scenario, the MSW landfill scenario releases a greater amount of arsenic from leachate in a more dilute form. The WTE scenario releases more chromium from the ash on an annual basis. The WTE facility and subsequent ash disposal greatly concentrates the chromium, often oxidizing it to the more toxic and mobile Cr(VI) form. Elevated arsenic and chromium concentrations in the ash leachate may increase leachate management costs.

Efficient Separation and Extraction of Vanadium and Chromium in High Chromium Vanadium Slag by Selective Two-Stage Roasting-Leaching

NASA Astrophysics Data System (ADS)

Wen, Jing; Jiang, Tao; Xu, Yingzhe; Liu, Jiayi; Xue, Xiangxin

2018-06-01

Vanadium and chromium are important rare metals, leading to a focus on high chromium vanadium slag (HCVS) as a potential raw material to extract vanadium and chromium in China. In this work, a novel method based on selective two-stage roasting-leaching was proposed to separate and extract vanadium and chromium efficiently in HCVS. XRD, FT-IR, and SEM were utilized to analyze the phase evolutions and microstructure during the whole process. Calcification roasting, which can calcify vanadium selectively using thermodynamics, was carried out in the first roasting stage to transfer vanadium into acid-soluble vanadate and leave chromium in the leaching residue as (Fe0.6Cr0.4)2O3 after H2SO4 leaching. When HCVS and CaO were mixed in the molar ratio CaO/V2O3 (n(CaO)/n(V2O3)) of 0.5 to 1.25, around 90 pct vanadium and less than 1 pct chromium were extracted in the first leaching liquid, thus achieving the separation of vanadium and chromium. In the second roasting stage, sodium salt, which combines with chromium easily, was added to the first leaching residue to extract chromium and 95.16 pct chromium was extracted under the optimal conditions. The total vanadium and chromium leaching rates were above 95 pct, achieving the efficient separation and extraction of vanadium and chromium. The established method provides a new technique to separate vanadium and chromium during roasting rather than in the liquid form, which is useful for the comprehensive application of HCVS.

Efficient Separation and Extraction of Vanadium and Chromium in High Chromium Vanadium Slag by Selective Two-Stage Roasting-Leaching

NASA Astrophysics Data System (ADS)

Wen, Jing; Jiang, Tao; Xu, Yingzhe; Liu, Jiayi; Xue, Xiangxin

2018-04-01

Vanadium and chromium are important rare metals, leading to a focus on high chromium vanadium slag (HCVS) as a potential raw material to extract vanadium and chromium in China. In this work, a novel method based on selective two-stage roasting-leaching was proposed to separate and extract vanadium and chromium efficiently in HCVS. XRD, FT-IR, and SEM were utilized to analyze the phase evolutions and microstructure during the whole process. Calcification roasting, which can calcify vanadium selectively using thermodynamics, was carried out in the first roasting stage to transfer vanadium into acid-soluble vanadate and leave chromium in the leaching residue as (Fe0.6Cr0.4)2O3 after H2SO4 leaching. When HCVS and CaO were mixed in the molar ratio CaO/V2O3 (n(CaO)/n(V2O3)) of 0.5 to 1.25, around 90 pct vanadium and less than 1 pct chromium were extracted in the first leaching liquid, thus achieving the separation of vanadium and chromium. In the second roasting stage, sodium salt, which combines with chromium easily, was added to the first leaching residue to extract chromium and 95.16 pct chromium was extracted under the optimal conditions. The total vanadium and chromium leaching rates were above 95 pct, achieving the efficient separation and extraction of vanadium and chromium. The established method provides a new technique to separate vanadium and chromium during roasting rather than in the liquid form, which is useful for the comprehensive application of HCVS.

Meeting the Challenge of Environmental Regulations in Europe and North America

DTIC Science & Technology

2011-02-08

salts • Electrolytic • Trivalent chromium • Rare earth salts • Sol Gel Socomor Finishing Technologies 24 Ce document et les informations qu’il contient...l’autorisation préalable et écrite de Safran. ASETS DEFENSE 2011 CHROMATE C.C. REPLACEMENT (3) TRIVALENT CHROMIUM • SUITABLE ONLY TO 1000, 3000, 5000...REPLACEMENT(4) ) - TRIVALENT CHROMIUM + TOP COAT - TRIVALENT CHROMIUM + INHIBITORS - OTHER CHEMISTRY BASED - SOL GEL Socomor Finishing Technologies

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

PubMed

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

A chemical family-based strategy for uncovering hidden bioactive molecules and multicomponent interactions in herbal medicines.

PubMed

Song, Hui-Peng; Wu, Si-Qi; Hao, Haiping; Chen, Jun; Lu, Jun; Xu, Xiaojun; Li, Ping; Yang, Hua

2016-03-30

Two concepts involving natural products were proposed and demonstrated in this paper. (1) Natural product libraries (e.g. herbal extract) are not perfect for bioactivity screening because of the vast complexity of compound compositions, and thus a library reconstruction procedure is necessary before screening. (2) The traditional mode of "screening single compound" could be improved to "screening single compound, drug combination and multicomponent interaction" due to the fact that herbal medicines work by integrative effects of multi-components rather than single effective constituents. Based on the two concepts, we established a novel strategy aiming to make screening easier and deeper. Using thrombin as the model enzyme, we firstly uncovered the minor lead compounds, potential drug combinations and multicomponent interactions in an herbal medicine of Dan-Qi pair, showing a significant advantage over previous methods. This strategy was expected to be a new and promising mode for investigation of herbal medicines.

Mitigation of chromium poisoning of cathodes in solid oxide fuel cells employing CuMn1.8O4 spinel coating on metallic interconnect

NASA Astrophysics Data System (ADS)

Wang, Ruofan; Sun, Zhihao; Pal, Uday B.; Gopalan, Srikanth; Basu, Soumendra N.

2018-02-01

Chromium poisoning is one of the major reasons for cathode performance degradation in solid oxide fuel cells (SOFCs). To mitigate the effect of Cr-poisoning, a protective coating on the surface of interconnect for suppressing Cr vaporization is necessary. Among the various coating materials, Cu-Mn spinel coating is considered to be a potential candidate due to their good thermal compatibility, high stability and good electronic conductivity at high temperature. In this study, Crofer 22 H meshes with no protective coating, those with commercial CuMn2O4 spinel coating and the ones with lab-developed CuMn1.8O4 spinel coating were investigated. The lab-developed CuMn1.8O4 spinel coating were deposited on Crofer 22 H mesh by electrophoretic deposition and densified by a reduction and re-oxidation process. With these different Crofer 22 H meshes (bare, CuMn2O4-coated, and CuMn1.8O4-coated), anode-supported SOFCs with Sr-doped LaMnO3-based cathode were electrochemically tested at 800 °C for total durations of up to 288 h. Comparing the mitigating effects of the two types of Cu-Mn spinel coatings on Cr-poisoning, it was found that the performance of the denser lab-developed CuMn1.8O4 spinel coating was distinctly better, showing no degradation in the cell electrochemical performance and significantly less Cr deposition near the cathode/electrolyte interface after the test.

Au/Cr Sputter Coating for the Protection of Alumina During Sliding at High Temperatures

NASA Technical Reports Server (NTRS)

Benoy, Patricia A.; Dellacorte, Christopher

1995-01-01

A sputter deposited bilayer coating of gold and chromium was investigated as a potential solid lubricant to protect alumina substrates in applications involving sliding at high temperature. The proposed lubricant was tested in a pin-on-disk tribometer with coated alumina disks sliding against uncoated alumina pins. Three test parameters; temperature, load, and sliding velocity were varied over a wide range in order to determine the performance envelope on the gold/chromium (Au/Cr) solid lubricant film. The tribo-tests were run in an air atmosphere at temperatures of 25 to 1000 C, under loads of 4.9 to 49.0 N and at sliding velocities from 1 to 15 m/sec. Post test analyses included surface profilometry, wear factor determination and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) examination of worn surfaces. Compared to unlubricated Al2O3 sliding, the use of the Au/Cr film reduced friction by 30 to 50 percent and wear by one to two orders of magnitude. Increases in test temperature resulted in lower friction and the Au/Cr film continued to provide low friction, about 0.3, even at 1000 C. Pin wear factors and friction were largely unaffected by increasing loads up to 29.4 N. Sliding velocity had essentially no effect on friction, however, increased velocity reduced coating life (total sliding distance). Based upon these research results, the Au/Cr film is a promising lubricant for moderately loaded, low speed applications operating at temperatures as high as 1000 C.

Chemical Disposition of Plutonium in Hanford Site Tank Wastes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Delegard, Calvin H.; Jones, Susan A.

2015-05-07

This report examines the chemical disposition of plutonium (Pu) in Hanford Site tank wastes, by itself and in its observed and potential interactions with the neutron absorbers aluminum (Al), cadmium (Cd), chromium (Cr), iron (Fe), manganese (Mn), nickel (Ni), and sodium (Na). Consideration also is given to the interactions of plutonium with uranium (U). No consideration of the disposition of uranium itself as an element with fissile isotopes is considered except tangentially with respect to its interaction as an absorber for plutonium. The report begins with a brief review of Hanford Site plutonium processes, examining the various means used tomore » recover plutonium from irradiated fuel and from scrap, and also examines the intermediate processing of plutonium to prepare useful chemical forms. The paper provides an overview of Hanford tank defined-waste–type compositions and some calculations of the ratios of plutonium to absorber elements in these waste types and in individual waste analyses. These assessments are based on Hanford tank waste inventory data derived from separately published, expert assessments of tank disposal records, process flowsheets, and chemical/radiochemical analyses. This work also investigates the distribution and expected speciation of plutonium in tank waste solution and solid phases. For the solid phases, both pure plutonium compounds and plutonium interactions with absorber elements are considered. These assessments of plutonium chemistry are based largely on analyses of idealized or simulated tank waste or strongly alkaline systems. The very limited information available on plutonium behavior, disposition, and speciation in genuine tank waste also is discussed. The assessments show that plutonium coprecipitates strongly with chromium, iron, manganese and uranium absorbers. Plutonium’s chemical interactions with aluminum, nickel, and sodium are minimal to non-existent. Credit for neutronic interaction of plutonium with these absorbers occurs only if they are physically proximal in solution or the plutonium present in the solid phase is intimately mixed with compounds or solutions of these absorbers. No information on the potential chemical interaction of plutonium with cadmium was found in the technical literature. Definitive evidence of sorption or adsorption of plutonium onto various solid phases from strongly alkaline media is less clear-cut, perhaps owing to fewer studies and to some well-attributed tests run under conditions exceeding the very low solubility of plutonium. The several studies that are well-founded show that only about half of the plutonium is adsorbed from waste solutions onto sludge solid phases. The organic complexants found in many Hanford tank waste solutions seem to decrease plutonium uptake onto solids. A number of studies show plutonium sorbs effectively onto sodium titanate. Finally, this report presents findings describing the behavior of plutonium vis-à-vis other elements during sludge dissolution in nitric acid based on Hanford tank waste experience gained by lab-scale tests, chemical and radiochemical sample characterization, and full-scale processing in preparation for strontium-90 recovery from PUREX sludges.« less

Special Advanced Studies for Pollution Prevention Delivery Order 0065: The Monitor - Winter 2001

DTIC Science & Technology

2001-04-01

were selected based on previous efforts. These alternatives included Alodine 2000, NCS Rainseal, Sanchem Full Process, and trivalent chromium . CTC’s IVD...12 Alternatives for Chromium Electroplating: ElectroSpark Deposition .................. 13...Requirements ............ 15 Aluminum Substitution for Cadmium/ Chromium ............................................... 16 Review of Cadmium Alternatives

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

EPA Science Inventory