Electrochemistry of cations in diopsidic melt - Determining diffusion rates and redox potentials from voltammetric curves

NASA Technical Reports Server (NTRS)

Colson, Russell O.; Haskin, Larry A.; Crane, Daniel

1990-01-01

Results are presented on determinations of reduction potentials and their temperature dependence of selected ions in diopsidic melt, by using linear sweep voltammetry. Diffusion coefficients were measured for cations of Eu, Mn, Cr, and In. Enthalpies and entropies of reduction were determined for the cations V(V), Cr(3+), Mn(2+), Mn(3+), Fe(2+), Cu(2+), Mo(VI), Sn(IV), and Eu(3+). Reduction potentials were used to study the structural state of cations in the melt.

Water-soluble Schiff base-actinyl complexes and their effect on the solvent extraction of f-elements

DOE PAGES

Hawkins, Cory A.; Bustillos, Christian G.; May, Iain; ...

2016-09-07

Conventional solvent extraction of selected f-element cations by bis(2-ethylhexyl)phosphoric acid (HDEHP) yields increased extraction from aqueous to organic solution along the series Np(V) < Cm(III) < Eu(III) < U(VI), with distribution ratios all within two orders of magnitude. However, in the presence of the water-soluble tetradentate Schiff base (N,N'-bis(5-sulfonatosalicylidene)-ethylenediamine or H 2salenSO 3), selective complexation of the two actinyl cations (Np(V) and U(VI)) resulted in an extraction order of Np(V) < U(VI) << Eu(III) < Cm(III). The extraction of neither Cm(III) or Eu(III) by HDEHP are significantly impacted by the presence of the aqueous phase Schiff base. Despite observed hydrolyticmore » decomposition of H 2salenSO 3 in aqueous solutions, the calculated high conditional stability constant (β 11 = 26) for the complex [UO 2(salenSO 3)] 2- demonstrates its capacity for aqueous hold-back of U(VI). UV-visible-NIR spectroscopy of solutions prepared with a Np(VI) stock and H 2salenSO 3 suggest that reduction of Np(VI) to Np(V) by the ligand was rapid, resulting in a pentavalent Np complex that was substantially retained in the aqueous phase. Lastly, results from 1H NMR of aqueous solutions of H 2salenSO 3 with U(VI) and La(III), Eu(III), and Lu(III) provides additional evidence that the ligand readily chelates U(VI), but has only weak interactions with trivalent lanthanide ions.« less

Enhancement strategies for Cu(II), Cr(III) and Cr(VI) remediation by a variety of seaweed species.

PubMed

Murphy, V; Hughes, H; McLoughlin, P

2009-07-15

Various chemical treatments have been applied to six brown, red and green seaweed species with a view to enhancing their metal removal for Cu(II), Cr(III) and Cr(VI). Treatment with acetone resulted in the greatest enhancement for both cationic and anionic species with relatively low mass losses (15-35%), indicating its low risk to biomass operational stability. Cation binding was increased by 69%, while the total Cr removal was augmented by 15%. Cr(VI) binding was shown to be an adsorption-coupled reduction, whereby Cr(VI) was bound to the biomass surface at pH 2 and subsequently reduced to Cr(III). Acetone treatment also resulted in biomasses that were capable of converting up to 83% of Cr(VI) in solution to Cr(III). Blocking of carboxyl and amino functionalities had significant negative effects both on total Cr removal as well as percentage conversion of Cr(VI) to Cr(III). Results therefore indicated the significant role played by these moieties in metal binding to these seaweeds. Potentiometric titrations displayed agreement between the degree of esterification and the decrease in Cu(II) removal for Ulva spp. and Polysiphonia lanosa. FTIR analysis identified changes in biomass functionality and availability after chemical modification, the results of which were in agreement with metal removal studies. In conclusion, these biosorbents represent suitable candidates to replace conventional removal technologies for metal bearing wastewaters, in particular for the detoxification of hazardous Cr(VI) waste streams.

Matrix isolation with an ion transfer device for interference-free simultaneous spectrophotometric determinations of hexavalent and trivalent chromium in a flow-based system.

PubMed

Ohira, Shin-Ichi; Nakamura, Koretaka; Chiba, Mitsuki; Dasgupta, Purnendu K; Toda, Kei

2017-03-01

Chromium speciation by spectrophotometric determination of hexavalent chromium (Cr(VI)) with diphenylcarbazide (DPC) has several problems. These include: (1) the inability to directly detect trivalent chromium (Cr(III)) with DPC, (2) positive interference in Cr(VI) determination by other metal cations and (3) negative interference by any reducing agent present in the sample. These are addressed with an ion transfer device (ITD) in a flow injection analysis system. We previously developed the ITD for electrodialytic separations. Here we separate oppositely charged Cr(III) and Cr(VI) species by the ITD into two different acceptor solutions within ~5 s. The acceptor solutions consist of buffered H 2 O 2 to oxidize the Cr(III) to Cr(VI). Then DPC is added to either acceptor to measure Cr(III) and Cr(VI) spectrophotometrically. The system was optimized to provide the same response for Cr(VI) and Cr(III) with limits of detection (LODs, S/N=3) of 0.5 μg L -1 for each and a throughput rate of 30 samples h -1 . The ITD separation was also effective for matrix isolation and reduction of interferences. Potential cationic interferences were not transferred into the anionic Cr(VI) acceptor stream. Much of the organic compounds in soil extracts were also eliminated as evidenced from standard addition and recovery studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Chromium(VI) sorption efficiency of acid-activated banana peel over organo-montmorillonite in aqueous solutions.

PubMed

Ashraf, Anam; Bibi, Irshad; Niazi, Nabeel Khan; Ok, Yong Sik; Murtaza, Ghulam; Shahid, Muhammad; Kunhikrishnan, Anitha; Li, Dongwei; Mahmood, Tariq

2017-07-03

In the present study, we examined sorption of chromate (Cr(VI)) to acid-activated banana peel (AABP) and organo-montmorillonite (O-mont) as a function of pH, initial Cr(VI) concentration at a sorbent dose of 4 g L -1 and at 20 ± 1°C in aqueous solutions. In sorption edge experiments, maximum Cr(VI) removal was obtained at pH 3 after 2 hours by AABP and O-mont (88% and 69%). Sorption isotherm data showed that the sorption capacity of AABP was higher than O-mont (15.1 vs. 6.67 mg g -1 , respectively, at pH 4). Freundlich and Langmuir models provided the best fits to describe Cr(VI) sorption onto AABP (R 2 = 0.97) and O-mont (R 2 = 0.96). Fourier transform infrared spectroscopy elucidated that for AABP mainly the -OH, -COOH, -NH 2 , and for O-mont intercalated amines and -OH surface functional groups were involved in Cr(VI) sorption. The scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDX) analyses, although partly, indicate that the (wt. %) proportion of cations (e.g., Ca, Mg) in AABP decreased after Cr(VI) sorption. This may be due to ion exchange of chromite (Cr(III)) (produced from Cr(VI) reduction) with cationic elements in AABP. Also, Cr(VI) desorption (using phosphate solution) from AABP was lower (29%) than that from O-mont (51%) up to the third regeneration cycle. This bench scale comparative study highlights that the utilization of widely available and low-cost acid-activated biomaterials has a greater potential than organo-clays for Cr(VI) removal in aqueous media. However, future studies are warranted to precisely delineate different mechanisms of Cr(VI) sorption/reduction by acid-activated biomaterials and organo-clays.

Incorporation of zero valent iron nanoparticles in the matrix of cationic resin beads for the remediation of Cr(VI) contaminated waters.

PubMed

Toli, Aikaterini; Chalastara, Konstantina; Mystrioti, Christiana; Xenidis, Anthimos; Papassiopi, Nymphodora

2016-07-01

The objective of present study was to obtain the fixation of nano zero valent iron (nZVI) particles on a permeable matrix and evaluate the performance of this composite material for the removal of Cr(VI) from contaminated waters. The experiments were carried out using the cationic resin Dowex 50WX2 as porous support of the iron nanoparticles. The work was carried out in two phases. The first phase involved the fixation of nZVI on the resin matrix. The resin granules were initially mixed with a FeCl3 solution to obtain the adsorption of Fe(III). Then the Fe(III) loaded resin (RFe) was treated with polyphenol solutions to obtain the reduction of Fe(III) to the elemental state. Two polyphenol solutions were tested as reductants, i.e. green tea extract and gallic acid. Green tea was found to be inefficient, probably due to the relatively big size of the contained polyphenol molecules, but gallic acid molecules were able to reach adsorbed Fe(III) and reduce the cations to the elemental state. The second phase was focused on the investigation of Cr(VI) reduction kinetics using the nanoiron loaded resins (R-nFe). It was found that the reduction follows a kinetic law of first order with respect to Cr(VI) and to the embedded nanoiron. Compared to other similar products, this composite material was found to have comparable performance regarding reaction rates and higher degree of iron utilization. Namely the rate constant for the reduction of Cr(VI), in the presence of 1 mM nZVI, was equivalent to 1.4 h of half-life time at pH 3.2 and increased to 24 h at pH 8.5. The degree of iron utilization was as high as 0.8 mol of reduced Cr(VI) per mole of iron. It was also found that this composite material can be easily regenerated and reused for Cr(VI) reduction without significant loss of efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

A new cation-exchange method for accurate field speciation of hexavalent chromium

USGS Publications Warehouse

Ball, J.W.; McCleskey, R. Blaine

2003-01-01

A new method for field speciation of Cr(VI) has been developed to meet present stringent regulatory standards and to overcome the limitations of existing methods. The method consists of passing a water sample through strong acid cation-exchange resin at the field site, where Cr(III) is retained while Cr(VI) passes into the effluent and is preserved for later determination. The method is simple, rapid, portable, and accurate, and makes use of readily available, inexpensive materials. Cr(VI) concentrations are determined later in the laboratory using any elemental analysis instrument sufficiently sensitive to measure the Cr(VI) concentrations of interest. The new method allows measurement of Cr(VI) concentrations as low as 0.05 ??g 1-1, storage of samples for at least several weeks prior to analysis, and use of readily available analytical instrumentation. Cr(VI) can be separated from Cr(III) between pH 2 and 11 at Cr(III)/Cr(VI) concentration ratios as high as 1000. The new method has demonstrated excellent comparability with two commonly used methods, the Hach Company direct colorimetric method and USEPA method 218.6. The new method is superior to the Hach direct colorimetric method owing to its relative sensitivity and simplicity. The new method is superior to USEPA method 218.6 in the presence of Fe(II) concentrations up to 1 mg 1-1 and Fe(III) concentrations up to 10 mg 1-1. Time stability of preserved samples is a significant advantage over the 24-h time constraint specified for USEPA method 218.6.

23 CFR 200.11 - Procedures for processing Title VI reviews.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 23 Highways 1 2010-04-01 2010-04-01 false Procedures for processing Title VI reviews. 200.11 Section 200.11 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.11 Procedures for processing Title...

23 CFR 200.11 - Procedures for processing Title VI reviews.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 23 Highways 1 2014-04-01 2014-04-01 false Procedures for processing Title VI reviews. 200.11 Section 200.11 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.11 Procedures for processing Title...

23 CFR 200.11 - Procedures for processing Title VI reviews.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 23 Highways 1 2011-04-01 2011-04-01 false Procedures for processing Title VI reviews. 200.11 Section 200.11 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.11 Procedures for processing Title...

23 CFR 200.11 - Procedures for processing Title VI reviews.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 23 Highways 1 2013-04-01 2013-04-01 false Procedures for processing Title VI reviews. 200.11 Section 200.11 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.11 Procedures for processing Title...

Syntheses and crystal structures of the rare-earth metal(III) bromide ortho-oxidotungstates(VI) with the formula REBr[WO4] (RE = Y, Gd-Yb)

NASA Astrophysics Data System (ADS)

Schustereit, Tanja; Schleid, Thomas; Hartenbach, Ingo

2015-10-01

The rare-earth metal(III) bromide ortho-oxidotungstates(VI) with the formula REBr[WO4] crystallize triclinically in space group P 1 bar (a = 689-693, b = 715-728, c = 1074-1107 pm, α = 103-106, β ≈ 108 and γ = 93-95°, Z = 4) for RE = Y, Gd-Yb. Their crystal structure is isotypic with the most examples of the formally analogous lanthanoid(III) bromide oxidomolybdates(VI) REBr[MoO4] with RE = Y, Pr, Nd, Sm, Gd-Lu. It contains two crystallographically different rare-earth metal(III) cations with coordination numbers of seven plus one for (RE1)3+ and seven for (RE2)3+. The (RE1)3+ cations are surrounded by three Br- and four plus one O2- anions forming distorted trigonal dodecahedra, while the (RE2)3+ cations exhibit a coordination environment of one Br- and six O2- anions in the shape of a monocapped trigonal prism. Furthermore, the structure contains two crystallographically independent, isolated tetrahedral [WO4]2- units. All these polyhedra are fused together to form 1 ∞ {REBr[WO4]} chains running along [012]. Since the title compounds, synthesized by solid-state reactions from the underlying binaries, emerge as pure phases according to X-ray powder diffractometry, spectroscopic and magnetic measurements were performed.

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

PubMed

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

2015-10-01

An ecofriendly green chemistry method using a natural biopolymer, Gum Kondagogu (GK) for the removal of U (VI) from aqueous, simulated nuclear effluents was studied. The adsorption characteristic of GK towards U (VI) from aqueous solution was studied at varied pH, contact time, adsorbent dose, initial U (VI) concentration and temperature using UV-Visible spectroscopy and ICP-MS. Maximum adsorption was seen at pH 4, 0.1% GK with 60 min contact time at room temperature. The GK- U (VI) composite was characterized by FT-IR, zeta potential, TEM and SEM-EDAX. The Langmuir isotherm was found to be 487 mg of U (VI) g(-1) of GK. The adsorption capacity and (%) of U (VI) was found to be 490 ± 5.4 mg g(-1) and 98.5%. Moreover adsorption of U (VI) by GK was not influenced by other cations present in the simulated effluents. The adsorbed U (VI) was efficiently stripped from composite using 1 M HCl. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electron-Transfer-Enhanced Cation-Cation Interactions in Homo- and Heterobimetallic Actinide Complexes: A Relativistic Density Functional Theory Study.

PubMed

Zheng, Ming; Chen, Fang-Yuan; Tian, Jia-Nan; Pan, Qing-Jiang

2018-04-02

To provide deep insight into cation-cation interactions (CCIs) involving hexavalent actinyl species that are major components in spent nuclear fuel and pose important implications for the effective removal of radiotoxic pollutants in the environment, a series of homo- and heterobimetallic actinide complexes supported by cyclopentadienyl (Cp) and polypyrrolic macrocycle (H 4 L) ligands were systematically investigated using relativistic density functional theory. The metal sort in both parts of (THF)(H 2 L)(OAn VI O) and (An') III Cp 3 from U to Np to Pu, as well as the substituent bonding to Cp from electron-donating Me to H to electron-withdrawing Cl, SiH 3 , and SiMe 3 , was changed. Over 0.70 electrons are unraveled to transfer from the electron-rich U III to the electron-deficient An VI of the actinyl moiety, leading to a more stable An V -U IV isomer; in contrast, uranylneptunium and uranylplutonium complexes behave as electron-resonance structures between VI-III and V-IV. These were further corroborated by geometrical and electronic structures. The energies of CCIs (i.e., O exo -An' bonds) were calculated to be -19.6 to -41.2 kcal/mol, affording those of OUO-Np (-23.9 kcal/mol) and OUO-Pu (-19.6 kcal/mol) with less electron transfer (ET) right at the low limit. Topological analyses of the electron density at the O exo -An' bond critical points demonstrate that the CCIs are ET or dative bonds in nature. A positive correlation has been built between the CCIs' strength and corresponding ET amount. It is concluded that the CCIs of O exo -An' are driven by the electrostatic attraction between the actinyl oxo atom (negative) and the actinide ion (positive) and enhanced by their ET. Finally, experimental syntheses of (THF)(H 2 L)(OU VI O)(An') III Cp 3 (An' = U and Np) were well reproduced by thermodynamic calculations that yielded negative free energies in a tetrahydrofuran solution but a positive one for their uranylplutonium analogue, which was synthetically inaccessible. So, our thermodynamics would provide implications for the synthetic possibility of other theoretically designed bimetallic actinide complexes.

Occurrence of hexavalent chromium in ground water in the western Mojave Desert, California

USGS Publications Warehouse

Ball, J.W.; Izbicki, J.A.

2004-01-01

About 200 samples from selected public supply, domestic, and observation wells completed in alluvial aquifers underlying the western Mojave Desert were analyzed for total dissolved Cr and Cr(VI). Because Cr(VI) is difficult to preserve, samples were analyzed by 3 methods. Chromium(VI) was determined in the field using both a direct colorimetric method and EPA method 218.6, and samples were speciated in the field for later analysis in the laboratory using a cation-exchange method developed for the study described in this paper. Comparison of the direct colorimetric method and EPA method 218.6 with the new cation-exchange method yielded r2 values of 0.9991 and 0.9992, respectively. Total dissolved Cr concentrations ranged from less than the 0.1 ??g/l detection limit to 60 ??g/l, and almost all the Cr present was Cr(VI). Near recharge areas along the mountain front pH values were near neutral, dissolved O2 concentrations were near saturation, and Cr(VI) concentrations were less than the 0.1 ??g/l detection limit. Chromium(VI) concentrations and pH values increased downgradient as long as dissolved O 2 was present. However, low Cr(VI) concentrations were associated with low dissolved O2 concentrations near ground-water discharge areas along dry lakes. Chromium(VI) concentrations as high as 60 ??g/l occurred in ground water from the Sheep Creek fan alluvial deposits weathered from mafic rock derived from the San Gabriel Mountains, and Cr(VI) concentrations as high as about 36 ??g/l were present in ground water from alluvial deposits weathered from less mafic granitic, metamorphic, and volcanic rocks. Chromium(III) was the predominant form of Cr only in areas where dissolved O2 concentrations were less than 1 mg/l and was detected at a median concentration of 0.1 ??g/l, owing to its low solubility in water of near-neutral pH. Depending on local hydrogeologic conditions and the distribution of dissolved O2, Cr(VI) concentrations may vary considerably with depth. Samples collected under pumping conditions from different depths within wells show that Cr(VI) concentrations can range from less than the 0.1 ??g/l detection limit to 36 ??g/l in a single well and that dissolved O2 concentrations likely control the concentration and redox speciation of Cr in ground water.

Metal-chelate dye-controlled organization of Cd32S14(SPh)40(4-) nanoclusters into three-dimensional molecular and covalent open architecture.

PubMed

Zheng, Nanfeng; Lu, Haiwei; Bu, Xianhui; Feng, Pingyun

2006-04-12

Chalcogenide II-VI nanoclusters are usually prepared as isolated clusters and have defied numerous efforts to join them into covalent open-framework architecture with conventional templating methods such as protonated amines or inorganic cations commonly used to direct the formation of porous frameworks. Herein, we report the first templated synthesis of II-VI covalent superlattices from large II-VI tetrahedral clusters (i.e., [Cd32S14(SPh)38]2-). Our method takes advantage of low charge density of metal-chelate dyes that is a unique match with three-dimensional II-VI semiconductor frameworks in charge density, surface hydrophilicity-hydrophobicity, and spatial organization. In addition, metal-chelate dyes also serve to tune the optical properties of resulting dye semiconductor composite materials.

Improved Bi Film Wrapped Single Walled Carbon Nanotubes for Ultrasensitive Electrochemical Detection of Trace Cr(VI).

PubMed

Ouyang, Ruizhuo; Zhang, Wangyao; Zhou, Shilin; Xue, Zi-Ling; Xu, Lina; Gu, Yingying; Miao, Yuqing

2013-12-15

We report here the successful fabrication of an improved Bi film wrapped single walled carbon nanotubes modified glassy carbon electrode (Bi/SWNTs/GCE) as a highly sensitive platform for ultratrace Cr(VI) detection through catalytic adsorptive cathodic stripping voltammetry (AdCSV). The introduction of negatively charged SWNTs extraordinarily decreased the size of Bi particles to nanoscale due to electrostatic interaction which made Bi(III) cations easily attracted onto the surface of SWNTs in good order, leading to higher quality of Bi film deposition. The obtained Bi/SWNTs composite was well characterized with electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), the static water contact angle and the voltammetric measurements. The results demonstrates the improvements in the quality of Bi film deposited on the surface of SWNTs such as faster speed of electron transfer, more uniform and smoother morphology, better hydrophilicity and higher stripping signal. Using diethylene triaminepentaacetic acid (DTPA) as complexing ligand, the fabricated electrode displays a well-defined and highly sensitive peak for the reduction of Cr(III)-DTPA complex at -1.06 V ( vs . Ag/AgCl) with a linear concentration range of 0-25 nM and a fairly low detection limit of 0.036 nM. No interference was found in the presence of coexisting ions, and good recoveries were achieved for the analysis of a river sample. In comparison to previous approaches using Bi film modified GCE, the newly designed electrode exhibits better reproducibility and repeatability towards aqueous detection of trace Cr(VI) and appears to be very promising as the basis of a highly sensitive and selective voltammetric procedure for Cr(VI) detection at trace level in real samples.

Improved Bi Film Wrapped Single Walled Carbon Nanotubes for Ultrasensitive Electrochemical Detection of Trace Cr(VI)

PubMed Central

Zhou, Shilin; Xue, Zi-Ling; Xu, Lina; Gu, Yingying; Miao, Yuqing

2014-01-01

We report here the successful fabrication of an improved Bi film wrapped single walled carbon nanotubes modified glassy carbon electrode (Bi/SWNTs/GCE) as a highly sensitive platform for ultratrace Cr(VI) detection through catalytic adsorptive cathodic stripping voltammetry (AdCSV). The introduction of negatively charged SWNTs extraordinarily decreased the size of Bi particles to nanoscale due to electrostatic interaction which made Bi(III) cations easily attracted onto the surface of SWNTs in good order, leading to higher quality of Bi film deposition. The obtained Bi/SWNTs composite was well characterized with electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), the static water contact angle and the voltammetric measurements. The results demonstrates the improvements in the quality of Bi film deposited on the surface of SWNTs such as faster speed of electron transfer, more uniform and smoother morphology, better hydrophilicity and higher stripping signal. Using diethylene triaminepentaacetic acid (DTPA) as complexing ligand, the fabricated electrode displays a well-defined and highly sensitive peak for the reduction of Cr(III)-DTPA complex at −1.06 V (vs. Ag/AgCl) with a linear concentration range of 0–25 nM and a fairly low detection limit of 0.036 nM. No interference was found in the presence of coexisting ions, and good recoveries were achieved for the analysis of a river sample. In comparison to previous approaches using Bi film modified GCE, the newly designed electrode exhibits better reproducibility and repeatability towards aqueous detection of trace Cr(VI) and appears to be very promising as the basis of a highly sensitive and selective voltammetric procedure for Cr(VI) detection at trace level in real samples. PMID:24771881

Kinetics of Cation and Oxyanion Adsorption and Desorption on Ferrihydrite: Roles of Ferrihydrite Binding Sites and a Unified Model

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

Tian, Lei; Shi, Zhenqing; Lu, Yang

Understanding the kinetics of toxic ion reactions with ferrihydrite is crucial for predicting the dynamic behavior of contaminants in soil environments. In this study, the kinetics of As(V), Cr(VI), Cu, and Pb adsorption and desorption on ferrihydrite were investigated with a combination of laboratory macroscopic experiments, microscopic investigation and mechanistic modeling. The rates of As(V), Cr(VI), Cu, and Pb adsorption and desorption on ferrihydrite, as systematically studied using a stirred-flow method, was highly dependent on the reaction pH and metal concentrations and varied significantly among four metals. Spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM) showed, at sub-nano scales, all fourmore » metals were distributed within the ferrihydrite particle aggregates homogeneously after adsorption reactions, with no evidence of surface diffusion-controlled processes. Based on experimental results, we developed a unifying kinetics model for both cation and oxyanion adsorption/desorption on ferrihydrite based on the mechanistic-based equilibrium model CD-MUSIC. Overall, the model described the kinetic results well, and we quantitatively demonstrated how the equilibrium properties of the cation and oxyanion binding to various ferrihydrite sites affected the adsorption and desorption rates. Our results provided a unifying quantitative modeling method for the kinetics of both cation and oxyanion adsorption/desorption on iron minerals.« less

Systematic approach for simultaneously correcting the band-gap and p - d separation errors of common cation III-V or II-VI binaries in density functional theory calculations within a local density approximation

DOE PAGES

Wang, Jianwei; Zhang, Yong; Wang, Lin-Wang

2015-07-31

We propose a systematic approach that can empirically correct three major errors typically found in a density functional theory (DFT) calculation within the local density approximation (LDA) simultaneously for a set of common cation binary semiconductors, such as III-V compounds, (Ga or In)X with X = N,P,As,Sb, and II-VI compounds, (Zn or Cd)X, with X = O,S,Se,Te. By correcting (1) the binary band gaps at high-symmetry points , L, X, (2) the separation of p-and d-orbital-derived valence bands, and (3) conduction band effective masses to experimental values and doing so simultaneously for common cation binaries, the resulting DFT-LDA-based quasi-first-principles methodmore » can be used to predict the electronic structure of complex materials involving multiple binaries with comparable accuracy but much less computational cost than a GW level theory. This approach provides an efficient way to evaluate the electronic structures and other material properties of complex systems, much needed for material discovery and design.« less

Systematic approach for simultaneously correcting the band-gap and p -d separation errors of common cation III-V or II-VI binaries in density functional theory calculations within a local density approximation

NASA Astrophysics Data System (ADS)

Wang, Jianwei; Zhang, Yong; Wang, Lin-Wang

2015-07-01

We propose a systematic approach that can empirically correct three major errors typically found in a density functional theory (DFT) calculation within the local density approximation (LDA) simultaneously for a set of common cation binary semiconductors, such as III-V compounds, (Ga or In)X with X =N ,P ,As ,Sb , and II-VI compounds, (Zn or Cd)X , with X =O ,S ,Se ,Te . By correcting (1) the binary band gaps at high-symmetry points Γ , L , X , (2) the separation of p -and d -orbital-derived valence bands, and (3) conduction band effective masses to experimental values and doing so simultaneously for common cation binaries, the resulting DFT-LDA-based quasi-first-principles method can be used to predict the electronic structure of complex materials involving multiple binaries with comparable accuracy but much less computational cost than a GW level theory. This approach provides an efficient way to evaluate the electronic structures and other material properties of complex systems, much needed for material discovery and design.

Electro-migration of heavy metals in an aged electroplating contaminated soil affected by the coexisting hexavalent chromium.

PubMed

Zhang, Weihua; Zhuang, Luwen; Tong, Lizhi; Lo, Irene M C; Qiu, Rongliang

2012-02-01

Cr(VI) was often reported to oxidize soil organic matter at acidic environments due to its high ORP, probably thus changing cationic metal species bound to soil organic matter, and influencing their electro-migration patterns. However, such an effect on the electro-migration was not confirmed in most previous studies. Therefore, this study applied a fixed voltage direct current field on an aged electroplating contaminated clayed soil, with a special interest in the direct or indirect influence of Cr(VI) on the electro-migration of other coexisting metals. After 353 h electrokinetic process, 81% of Zn, 53% of Ni and 22% of Cu in the original soil were electro-migrated into the electrolyte, and most of the remaining concentrated near the cathode. The Cr(VI) oxidized some soil organic matter along its migration pathway, with a pronounced reaction occurred near the anode at low pHs. The resulting Cr(III) reversed its original movement, and migrated towards the cathode, leading to the occurrence of a second Cr concentration peak in the soil. Metal species analyses showed that the amount of metals bound to soil organic matter significantly decreased, while a substantial increase in the Cr species bound to Fe/Mn (hydro-)oxides was observed, suggesting an enhancement of cationic metal electro-migration by the reduction of Cr(VI) into Cr(III). However, the Cr(VI) may form some stable lead chromate precipitates, and in turn demobilize Pb in the soil, as the results showed a low Pb removal and an increase in its acid-extractable and residual fractions after electrokinetic remediation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Particles from bird feather: a novel application of an ionic liquid and waste resource.

PubMed

Sun, Ping; Liu, Zhao-Tie; Liu, Zhong-Wen

2009-10-30

The dissolution and regeneration of the waste chicken feathers in an ionic liquid of 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) were demonstrated for preparing chicken feather based particles. The structure and properties of the regenerated chicken feathers were investigated by FT-IR, XRD, SEM, BET and water contact angle. The crystallinity of the regenerated chicken feathers was decreased, and the content of beta-sheet was 31.71%, which was clearly lower than the raw feather (47.19%). The surface property of chicken feather changed from hydrophobicity to hydrophilicity after regenerated from [BMIM]Cl as indicated by the change of the water contact angle from 138 to 76 degrees . The chicken feather particles regenerated from [BMIM]Cl showed an excellent efficiency (63.5-87.7%) for removing Cr(VI) ions in wastewater at the concentrations from 2 to 80 ppm. The Freundlich constant (k(F)) for the adsorption of Cr(VI) ion by the particles of the regenerated chicken feather was four times larger than that of the raw chicken feather, the possible reason is the hydrophilic groups such as amino and carboxyl groups were tend to self-assemble towards surface when the dissolved CF were regenerated by water, amino group will partly hydrate to cationic amino and Cr(VI) ion occurs as an anion in the aqueous phase, so the cationic amino will adsorb the anionic Cr(VI) ion onto the RCF particles through electrostatic attraction. This work demonstrated a new application of the ionic liquid for dissolving chicken feather and a renewable application of waste chicken feather for removing Cr(VI) ion in water.

Investigation of Proton Conductivity of Cation-Exchanged, Sulfonated Poly(b-Styrene-b-Isobutylene-b-Styrene) Membranes

DTIC Science & Technology

2009-09-01

solvents. Similar behavior was observed for Nafion -117 (also a polymer with ionic SO3H clusters) by other researchers (14). Results shown in this...pattern was only valid for ionic S-SIBS membranes exchanged with cations; neither acid form of SIBS-97-H nor Nafion -117 fell on this line. In order...10  vi INTENTIONALLY LEFT BLANK. 1 1. Introduction Research in ionic polymers has been gaining popularity in the scientific community

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

USGS Publications Warehouse

Yin, J.; Haggerty, R.; Stoliker, D.L.; Kent, D.B.; Istok, J.D.; Greskowiak, J.; Zachara, J.M.

2011-01-01

In the 300 Area of a U(VI)-contaminated aquifer at Hanford, Washington, USA, inorganic carbon and major cations, which have large impacts on U(VI) transport, change on an hourly and seasonal basis near the Columbia River. Batch and column experiments were conducted to investigate the factors controlling U(VI) adsorption/desorption by changing chemical conditions over time. Low alkalinity and low Ca concentrations (Columbia River water) enhanced adsorption and reduced aqueous concentrations. Conversely, high alkalinity and high Ca concentrations (Hanford groundwater) reduced adsorption and increased aqueous concentrations of U(VI). An equilibrium surface complexation model calibrated using laboratory batch experiments accounted for the decrease in U(VI) adsorption observed with increasing (bi)carbonate concentrations and other aqueous chemical conditions. In the column experiment, alternating pulses of river and groundwater caused swings in aqueous U(VI) concentration. A multispecies multirate surface complexation reactive transport model simulated most of the major U(VI) changes in two column experiments. The modeling results also indicated that U(VI) transport in the studied sediment could be simulated by using a single kinetic rate without loss of accuracy in the simulations. Moreover, the capability of the model to predict U(VI) transport in Hanford groundwater under transient chemical conditions depends significantly on the knowledge of real-time change of local groundwater chemistry. Copyright 2011 by the American Geophysical Union.

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

USGS Publications Warehouse

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

2011-01-01

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

Removal of chromium(VI) from water and wastewater using surfactant modified coconut coir pith as a biosorbent.

PubMed

Namasivayam, C; Sureshkumar, M V

2008-05-01

Coconut coir pith, an agricultural solid waste was used as biosorbent for the removal of chromium(VI) after modification with a cationic surfactant, hexadecyltrimethylammonium bromide. Optimum pH for Cr(VI) adsorption was found to be 2.0. Reduction of Cr(VI) to Cr(III) occurred to a slight extent during the removal. Langmuir, Freundlich and Dubinin Radushkevich (D-R) isotherms were used to model the adsorption equilibrium data and the system followed all the three isotherms. The adsorption capacity of the biosorbent was found to be 76.3 mg g(-1), which is higher or comparable to the adsorption capacity of various adsorbents reported in literature. Kinetic studies showed that the adsorption obeyed second order and Elovich model. Thermodynamic parameters such as delta G0, delta H0 and delta S0 were evaluated, indicating that the overall adsorption process was endothermic and spontaneous. Effects of foreign anions were also examined. The adsorbent was also tested for the removal of Cr(VI) from electroplating effluent.

Adsorption studies of heavy metal ions on mesoporous aluminosilicate, novel cation exchanger.

PubMed

Sepehrian, H; Ahmadi, S J; Waqif-Husain, S; Faghihian, H; Alighanbari, H

2010-04-15

Mesoporous aluminosilicates, have been prepared with various mole ratios of Si/Al and Cethyltrimethylammonium bromide (CTAB). They have been characterized by XRD, nitrogen adsorption/desorption measurements, FT-IR and thermogravimetry. Adsorption behavior of heavy metal ions on this adsorbent have been studied and discussed. The results show that incorporation of aluminum ions in the framework of the mesoporous MCM-41 has transformed it into an effective cation exchanger. The K(d) values of several metal ions have been increased. Separation of Sr(II)-Ce(III), Sr(II)-U(VI) and Cd(II)-Ce(III) has been developed on columns of this novel mesoporous cation exchanger. 2009 Elsevier B.V. All rights reserved.

Evaluation of sequential extraction procedures for soluble and insoluble hexavalent chromium compounds in workplace air samples.

PubMed

Ashley, Kevin; Applegate, Gregory T; Marcy, A Dale; Drake, Pamela L; Pierce, Paul A; Carabin, Nathalie; Demange, Martine

2009-02-01

Because toxicities may differ for Cr(VI) compounds of varying solubility, some countries and organizations have promulgated different occupational exposure limits (OELs) for soluble and insoluble hexavalent chromium (Cr(VI)) compounds, and analytical methods are needed to determine these species in workplace air samples. To address this need, international standard methods ASTM D6832 and ISO 16740 have been published that describe sequential extraction techniques for soluble and insoluble Cr(VI) in samples collected from occupational settings. However, no published performance data were previously available for these Cr(VI) sequential extraction procedures. In this work, the sequential extraction methods outlined in the relevant international standards were investigated. The procedures tested involved the use of either deionized water or an ammonium sulfate/ammonium hydroxide buffer solution to target soluble Cr(VI) species. This was followed by extraction in a sodium carbonate/sodium hydroxide buffer solution to dissolve insoluble Cr(VI) compounds. Three-step sequential extraction with (1) water, (2) sulfate buffer and (3) carbonate buffer was also investigated. Sequential extractions were carried out on spiked samples of soluble, sparingly soluble and insoluble Cr(VI) compounds, and analyses were then generally carried out by using the diphenylcarbazide method. Similar experiments were performed on paint pigment samples and on airborne particulate filter samples collected from stainless steel welding. Potential interferences from soluble and insoluble Cr(III) compounds, as well as from Fe(II), were investigated. Interferences from Cr(III) species were generally absent, while the presence of Fe(II) resulted in low Cr(VI) recoveries. Two-step sequential extraction of spiked samples with (first) either water or sulfate buffer, and then carbonate buffer, yielded quantitative recoveries of soluble Cr(VI) and insoluble Cr(VI), respectively. Three-step sequential extraction gave excessively high recoveries of soluble Cr(VI), low recoveries of sparingly soluble Cr(VI), and quantitative recoveries of insoluble Cr(VI). Experiments on paint pigment samples using two-step extraction with water and carbonate buffer yielded varying percentages of relative fractions of soluble and insoluble Cr(VI). Sequential extractions of stainless steel welding fume air filter samples demonstrated the predominance of soluble Cr(VI) compounds in such samples. The performance data obtained in this work support the Cr(VI) sequential extraction procedures described in the international standards.

43 CFR 17.336 - Hearings, decisions, post-termination proceedings.

Code of Federal Regulations, 2010 CFR

2010-10-01

...-termination proceedings. Certain DOI procedural provisions applicable to title VI of the Civil Rights Act of 1964 apply to DOI's enforcement of these regulations. The procedural provisions of DOI's Title VI...

43 CFR 17.336 - Hearings, decisions, post-termination proceedings.

Code of Federal Regulations, 2011 CFR

2011-10-01

...-termination proceedings. Certain DOI procedural provisions applicable to title VI of the Civil Rights Act of 1964 apply to DOI's enforcement of these regulations. The procedural provisions of DOI's Title VI...

Feasibility of Valve-in-Valve Procedure for Degenerated St. Jude Medical Trifecta Bioprosthesis.

PubMed

Verhoye, Jean-philippe; Harmouche, Majid; Soulami, Reda Belhaj; Thebault, Christophe; Boulmier, Dominique; Leguerrier, Alain; Anselmi, Amedeo

2015-07-01

The valve-in-valve (ViV) procedure is an option for patients with symptomatic structural degeneration of a bioprosthesis and excessive reoperative risk. The risk of coronary obstruction appears to be increased if ViV is performed for certain pericardial prostheses in which the leaflets are mounted outside the stent posts. Herein is described a successful ViV for a degenerated Trifecta aortic bioprosthesis, and the technical considerations for performing a ViV procedure within such types of prosthesis are considered. Emphasis is placed on the importance of preoperative investigations (computed tomography scan-based measurements of coronary ostial height and of sinus of Valsalva diameters), and on the precise deployment of the valve (transapical approach with transesophageal echocardiography control) to minimize the risk of major complications. The presence of a failing Trifecta bioprosthesis should not be considered an absolute contraindication to ViV on the basis of the risk of coronary obstruction.

Metal interferences and their removal prior to the determination of As(T) and As(III) in acid mine waters by hydride generation atomic absorption spectrometry

USGS Publications Warehouse

McCleskey, R. Blaine; Nordstrom, D. Kirk; Ball, James W.

2003-01-01

Hydride generation atomic absorption spectrometry (HGAAS) is a sensitive and selective method for the determination of total arsenic (arsenic(III) plus arsenic(V)) and arsenic(III); however, it is subject to metal interferences for acid mine waters. Sodium borohydride is used to produce arsine gas, but high metal concentrations can suppress arsine production. This report investigates interferences of sixteen metal species including aluminum, antimony(III), antimony(V), cadmium, chromium(III), chromium(IV), cobalt, copper(II), iron(III), iron(II), lead, manganese, nickel, selenium(IV), selenium(VI), and zinc ranging in concentration from 0 to 1,000 milligrams per liter and offers a method for removing interfering metal cations with cation exchange resin. The degree of interference for each metal without cation-exchange on the determination of total arsenic and arsenic(III) was evaluated by spiking synthetic samples containing arsenic(III) and arsenic(V) with the potential interfering metal. Total arsenic recoveries ranged from 92 to 102 percent for all metals tested except antimony(III) and antimony(V) which suppressed arsine formation when the antimony(III)/total arsenic molar ratio exceeded 4 or the antimony(V)/total arsenic molar ratio exceeded 2. Arsenic(III) recoveries for samples spiked with aluminum, chromium(III), cobalt, iron(II), lead, manganese, nickel, selenium(VI), and zinc ranged from 84 to 107 percent over the entire concentration range tested. Low arsenic(III) recoveries occurred when the molar ratios of metals to arsenic(III) were copper greater than 120, iron(III) greater than 70, chromium(VI) greater than 2, cadmium greater than 800, antimony(III) greater than 3, antimony(V) greater than 12, or selenium(IV) greater than 1. Low recoveries result when interfering metals compete for available sodium borohydride, causing incomplete arsine production, or when the interfering metal oxidizes arsenic(III). Separation of interfering metal cations using cation-exchange prior to hydridegeneration permits accurate arsenic(III) determinations in acid mine waters containing high concentrations of interfering metals. Stabilization of the arsenic redox species for as many as 15 months is demonstrated for samples that have been properly filtered and acidified with HCl in the field. The detection limits for the method described in this report are 0.1 micrograms per liter for total arsenic and 0.8 micrograms per liter for arsenic(III).

Metals removal from aqueous solution by iron-based bonding agents.

PubMed

Deliyanni, Eleni A; Lazaridis, Nikolaos K; Peleka, Efrosini N; Matis, Konstantinos A

2004-01-01

GOAL AND SCOPE AND BACKGROUND: The application of a promising method, termed sorptive flotation, for the removal of chromium(VI) and zinc ions was the aim of the present paper. A special case of sorptive flotation is adsorbing colloid flotation. Suitable sorbent preparation techniques have been developed in the laboratory. Sorptive flotation, consisting of the sorption and flotation processes combined in series, has proved to give fast and satisfactory treatment of the industrial streams and effluents bearing dilute aqueous solutions of zinc and chromium(VI). Goethite has proved to be effective for the removal of chromium(VI) and zinc ions. Also, adsorbing colloid flotation with ferric hydroxide (as the co-precipitant) could be an alternative method to the above-mentioned separation of metal ions. In both cases, chromium(VI) (pH=4) and zinc (pH=7) removal was about 100%. The reasons for selecting the iron-based bonding materials, like goethite and/or in-situ produced ferric hydroxide, are that they are cheap, easily synthesized, suitable both for cation and anion sorption, and, furthermore, that they present low risks for adding a further pollutant to the system. Promising results were obtained. The application of goethite and in-situ produced ferric hydroxide has demonstrated their effectiveness in the removal of heavy metal ions, such as chromium anions and zinc cations. A proposed continuation of current work is the utilization of similar iron oxides, for instance synthesized akaganeite. The comparison between the results reported in this paper with the results reported in the literature, also deserves attention.

Modulation of hexavalent chromium toxicity on Οriganum vulgare in an acidic soil amended with peat, lime, and zeolite.

PubMed

Antoniadis, Vasileios; Zanni, Anna A; Levizou, Efi; Shaheen, Sabry M; Dimirkou, Anthoula; Bolan, Nanthi; Rinklebe, Jörg

2018-03-01

Dynamics of chromate (Cr(VI)) in contaminated soils may be modulated by decreasing its phytoavailability via the addition of organic matter-rich amendments, which might accelerate Cr(VI) reduction to inert chromite (Cr(III)) or high-cation exchange capacity amendments. We studied Cr(VI) phytoavailability of oregano in a Cr(VI)-spiked acidic soil non-treated (S) and treated with peat (SP), lime (SL), and zeolite (SZ). The addition of Cr(VI) increased the concentrations of Cr(VI) and Cr(III) in soils and plants, especially in the lime-amended soil. The plant biomass decreased in the lime-amended soil compared to the un-spiked soil (control) due to decreased plant phosphorus concentrations and high Cr(VI) concentrations in root at that treatment. Oregano in the peat-amended soil exhibited significantly less toxic effects, due to the role of organic matter in reducing toxic Cr(VI) to Cr(III) and boosted plant vigour in this treatment. In the lime-amended soil, the parameters of soil Cr(VI), soil Cr(III), and root Cr(III) increased significantly compared to the non-amended soil, indicating that Cr(VI) reduction to Cr(III) was accelerated at high pH. Added zeolite failed to decreased Cr(VI) level to soil and plant. Oregano achieved a total uptake of Cr(III) and Cr(VI) of 0.275 mg in plant kg -1 soil in a pot in the non-amended soil. We conclude that peat as soil amendment might be considered as a suitable option for decreasing Cr(VI) toxicity in soil and plant, and that oregano as tolerant plant species has a certain potential to be used as a Cr accumulator. Copyright © 2017 Elsevier Ltd. All rights reserved.

A highly sensitive and selective electrochemical sensor for determination of Cr(VI) in the presence of Cr(III) using modified multi-walled carbon nanotubes/quercetin screen-printed electrode.

PubMed

Sadeghi, Susan; Garmroodi, Aziz

2013-12-01

A novel screen-printed carbon electrode modified with quercetin/multi-walled carbon nanotubes was fabricated for determination of Cr(VI) in the presence of excess of Cr(III) without any pretreatment. The method is based on accumulation of the quercetin-Cr(III) complex generated in situ from Cr(VI) at the modified electrode surface in an open circuit followed by differential pulse voltammetry detection. The new method allowed selective determination of Cr(VI) in the presence of Cr(III). The influence of various parameters affecting the adsorptive stripping voltammetry performance was investigated. Under the optimum conditions, the calibration plot was found to be linear in the Cr(VI) concentration range from 1.0 to 200 μmol(-1) with a limit of detection(S/N=3) of 0.3 μmol L(-1). The relative standard deviation (RSD%) of seven replicates of the current measurements for a 50 μmol(-1) of Cr(VI) solution was 3.0%. The developed electrode displayed a very low or no sensitivity to alkali, alkali-earth and transition metal cations and was successfully applied for the determination of Cr(VI) in drinking water samples. © 2013.

Preparation of graphene oxide-manganese dioxide for highly efficient adsorption and separation of Th(IV)/U(VI).

PubMed

Pan, Ning; Li, Long; Ding, Jie; Li, Shengke; Wang, Ruibing; Jin, Yongdong; Wang, Xiangke; Xia, Chuanqin

2016-05-15

Manganese dioxide decorated graphene oxide (GOM) was prepared via fixation of crystallographic MnO2 (α, γ) on the surface of graphene oxide (GO) and was explored as an adsorbent material for simultaneous removal of thorium/uranium ions from aqueous solutions. In single component systems (Th(IV) or U(VI)), the α-GOM2 (the weight ratio of GO/α-MnO2 of 2) exhibited higher maximum adsorption capacities toward both Th(IV) (497.5mg/g) and U(VI) (185.2 mg/g) than those of GO. In the binary component system (Th(IV)/U(VI)), the saturated adsorption capacity of Th(IV) (408.8 mg/g)/U(VI) (66.8 mg/g) on α-GOM2 was also higher than those on GO. Based on the analysis of various data, it was proposed that the adsorption process may involve four types of molecular interactions including coordination, electrostatic interaction, cation-pi interaction, and Lewis acid-base interaction between Th(IV)/U(VI) and α-GOM2. Finally, the Th(IV)/U(VI) ions on α-GOM2 can be separated by a two-stage desorption process with Na2CO3/EDTA. Those results displayed that the α-GOM2 may be utilized as an potential adsorbent for removing and separating Th(IV)/U(VI) ions from aqueous solutions. Copyright © 2016 Elsevier B.V. All rights reserved.

A procedure for quantitation of total oxidized uranium for bioremediation studies

USGS Publications Warehouse

Elias, Dwayne A.; Senko, John M.; Krumholz, Lee R.

2003-01-01

A procedure was developed for the quantitation of complexed U(VI) during studies on U(VI) bioremediation. These studies typically involve conversion of soluble or complexed U(VI) (oxidized) to U(IV) (the reduced form which is much less soluble). Since U(VI) freely exchanges between material adsorbed to the solid phase and the dissolved phase, uranium bioremediation experiments require a mass balance of U in both its soluble and adsorbed forms as well as in the reduced sediment bound phase. We set out to optimize a procedure for extraction and quantitation of sediment bound U(VI). Various extractant volumes to sediment ratios were tested and it was found that between 1:1 to 8:1 ratios (v/w) there was a steady increase in U(VI) recovered, but no change with further increases in v/w ratio.Various strengths of NaHCO3, Na-EDTA, and Na-citrate were used to evaluate complexed U(VI) recovery, while the efficiency of a single versus repeated extraction steps was compared with synthesized uranyl-phosphate and uranyl-hydroxide. Total recovery with 1 M NaHCO3 was 95.7% and 97.9% from uranyl-phosphate and uranyl-hydroxide, respectively, compared to 80.7% and 89.9% using 450 mM NaHCO3. Performing the procedure once yielded an efficiency of 81.1% and 92.3% for uranyl-phosphate and uranyl-hydroxide, respectively, as compared to three times. All other extractants yielded 7.9–82.0% in both experiments.

Cation–cation interactions and cation exchange in a series of isostructural framework uranyl tungstates

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

Balboni, Enrica; Burns, Peter C., E-mail: pburns@nd.edu; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556

2014-05-01

The isotypical compounds (UO{sub 2}){sub 3}(WO{sub 6})(H{sub 2}O){sub 5} (1), Ag(UO{sub 2}){sub 3}(WO{sub 6})(OH)(H{sub 2}O){sub 3} (2), K(UO{sub 2}){sub 3}(WO{sub 6})OH(H{sub 2}O){sub 4} (3), Rb(UO{sub 2}){sub 3}(WO{sub 6})(OH)(H{sub 2}O){sub 3.5} (4), and Cs(UO{sub 2}){sub 3}(WO{sub 6})OH(H{sub 2}O){sub 3} (5) were synthesized, characterized, and their structures determined. Each crystallizes in space group Cc. (1): a=12.979 (3), b=10.238 (2), c=11.302 (2), β=102.044 (2); (2): a=13.148 (2), b=9.520 (1), c=11.083 (2), β=101.568 (2); (3): a=13.111 (8), b=9.930 (6), c=11.242 (7), β=101.024 (7); (4): a=12.940 (2), b=10.231 (2), c=11.259(2), β=102.205 (2); (5): a=12.983 (3), b=10.191 (3), c=11.263 (4), β=101.661 (4). Compounds 1–5 are amore » framework of uranyl and tungsten polyhedra containing cation–cation interactions. The framework has three symmetrically distinct U(VI) cations, one tungsten, sixteen to eighteen oxygen atoms, and in 2–5, one monovalent cation. Each atom occupies a general position. Each U(VI) cation is present as a typical (UO{sub 2}){sup 2+} uranyl ion in an overall pentagonal bipyramidal coordination environment. Each pentagonal bipyramid shares two equatorial edges with two other pentagonal bipyramids, forming a trimer. Trimers are connected into chains by edge-sharing with WO{sub 6} octahedra. Chains are linked through cation–cation interactions between two symmetrically independent uranyl ions. This yields a remarkably complex system of intersecting channels that extend along [0 0 1] and [−1 1 0]. The cation exchange properties of 2 and 3 were characterized at room temperature and at 140 °C. - Graphical abstract: Chains of uranium and tungsten polyhedra are connected into a three dimensional framework by cation–cation interactions occurring between two symmetrically independent uranyl pentagonal bipyramids. Monovalent cations present in channels within the structure can be exchanged by room temperature or mild hydrothermal treatments. The framework of these compounds is robust to cation exchange and heat. (yellow polyhedra=uranium pentagonal bipyramids; blue polyhedra=tungsten octahedral, purple balls=K; yellow balls=Na; grey balls=Tl). - Highlights: • Five isostructural uranyl tungstates compounds were synthesized hydrothermally. • The structures consist of a chains of uranium and tungstate polyhedral. • Chains are connected into a framework by cation–cation interactions. • Cation exchange does not alter the structural integrity of the compounds. • Cation exchange was successful at room temperature and mild hydrothermal conditions.« less

23 CFR 200.7 - FHWA Title VI policy.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 23 Highways 1 2010-04-01 2010-04-01 false FHWA Title VI policy. 200.7 Section 200.7 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.7 FHWA Title VI policy. It is the policy of the FHWA to...

23 CFR 200.7 - FHWA Title VI policy.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 23 Highways 1 2011-04-01 2011-04-01 false FHWA Title VI policy. 200.7 Section 200.7 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.7 FHWA Title VI policy. It is the policy of the FHWA to...

23 CFR 200.7 - FHWA Title VI policy.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 23 Highways 1 2014-04-01 2014-04-01 false FHWA Title VI policy. 200.7 Section 200.7 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.7 FHWA Title VI policy. It is the policy of the FHWA to...

23 CFR 200.7 - FHWA Title VI policy.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 23 Highways 1 2013-04-01 2013-04-01 false FHWA Title VI policy. 200.7 Section 200.7 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.7 FHWA Title VI policy. It is the policy of the FHWA to...

Gas Phase Reactions of Ions Derived from Anionic Uranyl Formate and Uranyl Acetate Complexes.

PubMed

Perez, Evan; Hanley, Cassandra; Koehler, Stephen; Pestok, Jordan; Polonsky, Nevo; Van Stipdonk, Michael

2016-12-01

The speciation and reactivity of uranium are topics of sustained interest because of their importance to the development of nuclear fuel processing methods, and a more complete understanding of the factors that govern the mobility and fate of the element in the environment. Tandem mass spectrometry can be used to examine the intrinsic reactivity (i.e., free from influence of solvent and other condensed phase effects) of a wide range of metal ion complexes in a species-specific fashion. Here, electrospray ionization, collision-induced dissociation, and gas-phase ion-molecule reactions were used to create and characterize ions derived from precursors composed of uranyl cation (U VI O 2 2+ ) coordinated by formate or acetate ligands. Anionic complexes containing U VI O 2 2+ and formate ligands fragment by decarboxylation and elimination of CH 2 =O, ultimately to produce an oxo-hydride species [U VI O 2 (O)(H)] - . Cationic species ultimately dissociate to make [U VI O 2 (OH)] + . Anionic complexes containing acetate ligands exhibit an initial loss of acetyloxyl radical, CH 3 CO 2 •, with associated reduction of uranyl to U V O 2 + . Subsequent CID steps cause elimination of CO 2 and CH 4 , ultimately to produce [U V O 2 (O)] - . Loss of CH 4 occurs by an intra-complex H + transfer process that leaves U V O 2 + coordinated by acetate and acetate enolate ligands. A subsequent dissociation step causes elimination of CH 2 =C=O to leave [U V O 2 (O)] - . Elimination of CH 4 is also observed as a result of hydrolysis caused by ion-molecule reaction with H 2 O. The reactions of other anionic species with gas-phase H 2 O create hydroxyl products, presumably through the elimination of H 2 . Graphical Abstract ᅟ.

The interstitial distribution of macromolecules in rat tumours is influenced by the negatively charged matrix components

PubMed Central

Wiig, Helge; Gyenge, Christina C; Tenstad, Olav

2005-01-01

Knowledge of macromolecular distribution volumes is essential in understanding fluid transport within normal and pathological tissues. In this study in vivo we determined the distribution volumes of several macromolecules, including one monoclonal antibody, in tumours and tested whether charges associated with the tumour extracellular matrix influence their available volumes. Steady state levels of the monoclonal antibody trastuzumab (Herceptin) (pI = 9.2), IgG (pI = 7.6) as well as native (pI = 5.0) and cationized albumin (pI = 7.6) were established in rats bearing dimethylbenzanthracene (DMBA)-induced mammary tumours by continuous infusion using osmotic minipumps. After a 5–7 day infusion period, the rats were nephrectomized and the extracellular volume was determined with 51Cr-labelled EDTA. Plasma volumes were measured with 125I-labelled human serum albumin or rat IgM in a separate series. Steady state concentrations of probes were determined in the interstitial fluid that was isolated by centrifugation from tumours or by post mortem wick implantation in the back skin. Calculations were made for interstitial fluid volume (Vi), along with the available (Va/Vi) and excluded (Ve/Vi) relative interstitial volume fractions. The Ve/Vi for the positively charged trastuzumab in tumours averaged 0.29 ± 0.03 (n = 16), a value which was significantly lower than the corresponding one for IgG of 0.36 ± 0.02 (n = 16). Native albumin was excluded from 38% of the tumour interstitial fluid, whereas cationization of albumin reduced the excluded volume by ∼50%. Our experiments suggest that the tumour interstitium acts as a negatively charged matrix and is an important factor in determining the macromolecular distribution volume. PMID:15994186

The interstitial distribution of macromolecules in rat tumours is influenced by the negatively charged matrix components.

PubMed

Wiig, Helge; Gyenge, Christina C; Tenstad, Olav

2005-09-01

Knowledge of macromolecular distribution volumes is essential in understanding fluid transport within normal and pathological tissues. In this study in vivo we determined the distribution volumes of several macromolecules, including one monoclonal antibody, in tumours and tested whether charges associated with the tumour extracellular matrix influence their available volumes. Steady state levels of the monoclonal antibody trastuzumab (Herceptin) (pI = 9.2), IgG (pI = 7.6) as well as native (pI = 5.0) and cationized albumin (pI = 7.6) were established in rats bearing dimethylbenzanthracene (DMBA)-induced mammary tumours by continuous infusion using osmotic minipumps. After a 5-7 day infusion period, the rats were nephrectomized and the extracellular volume was determined with 51Cr-labelled EDTA. Plasma volumes were measured with 125I-labelled human serum albumin or rat IgM in a separate series. Steady state concentrations of probes were determined in the interstitial fluid that was isolated by centrifugation from tumours or by post mortem wick implantation in the back skin. Calculations were made for interstitial fluid volume (Vi), along with the available (Va/Vi) and excluded (Ve/Vi) relative interstitial volume fractions. The Ve/Vi for the positively charged trastuzumab in tumours averaged 0.29 +/- 0.03 (n = 16), a value which was significantly lower than the corresponding one for IgG of 0.36 +/- 0.02 (n = 16). Native albumin was excluded from 38% of the tumour interstitial fluid, whereas cationization of albumin reduced the excluded volume by approximately 50%. Our experiments suggest that the tumour interstitium acts as a negatively charged matrix and is an important factor in determining the macromolecular distribution volume.

A transferable force field for CdS-CdSe-PbS-PbSe solid systems

NASA Astrophysics Data System (ADS)

Fan, Zhaochuan; Koster, Rik S.; Wang, Shuaiwei; Fang, Changming; Yalcin, Anil O.; Tichelaar, Frans D.; Zandbergen, Henny W.; van Huis, Marijn A.; Vlugt, Thijs J. H.

2014-12-01

A transferable force field for the PbSe-CdSe solid system using the partially charged rigid ion model has been successfully developed and was used to study the cation exchange in PbSe-CdSe heteronanocrystals [A. O. Yalcin et al., "Atomic resolution monitoring of cation exchange in CdSe-PbSe heteronanocrystals during epitaxial solid-solid-vapor growth," Nano Lett. 14, 3661-3667 (2014)]. In this work, we extend this force field by including another two important binary semiconductors, PbS and CdS, and provide detailed information on the validation of this force field. The parameterization combines Bader charge analysis, empirical fitting, and ab initio energy surface fitting. When compared with experimental data and density functional theory calculations, it is shown that a wide range of physical properties of bulk PbS, PbSe, CdS, CdSe, and their mixed phases can be accurately reproduced using this force field. The choice of functional forms and parameterization strategy is demonstrated to be rational and effective. This transferable force field can be used in various studies on II-VI and IV-VI semiconductor materials consisting of CdS, CdSe, PbS, and PbSe. Here, we demonstrate the applicability of the force field model by molecular dynamics simulations whereby transformations are initiated by cation exchange.

Group Hexavalent Actinide Separations: A New Approach to Used Nuclear Fuel Recycling

DOE PAGES

Burns, Jonathan D.; Moyer, Bruce A.

2016-08-17

Hexavalent Np, Pu, and Am individually, and as a group, have all been cocrystallized with UO 2(NO 3) 2∙ 6H 2O, constituting the first demonstration of an An(VI) group cocrystalliza- tion. The hexavalent dioxo cations of Np, Pu, and Am cocrystallize with UO 2(NO 3) 2∙ 6H 2O in near proportion with a simple reduction in temperature, while the lower valence states, An(III) and An(IV), are only slightly removed from solution. A separation of An(VI) species from An(III) ions by crystallization has been demonstrated, with an observed separation factor of 14. Separation of An(VI) species from key fission products, 95Zr,more » 95Nb, 137Cs, and 144Ce, has also been demonstrated by crystallization, with separation factors ranging from 6.5 to 71 in the absence of Am(VI), while in the presence of Am(VI), the separation factors were reduced to 0.99 7.7. One interesting observation is that Am(VI) shows increased stability in the cocrystallized form, with no reduction observed after 13 days, as opposed to in solution, in which >50% is reduced after only 10 days. The ability to cocrystallize and stabilize hexavalent actinides from solution, especially Am(VI), introduces a new separations approach that can be applied to closing the nuclear fuel cycle.« less

Group Hexavalent Actinide Separations: A New Approach to Used Nuclear Fuel Recycling

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

Burns, Jonathan D.; Moyer, Bruce A.

Hexavalent Np, Pu, and Am individually, and as a group, have all been cocrystallized with UO 2(NO 3) 2∙ 6H 2O, constituting the first demonstration of an An(VI) group cocrystalliza- tion. The hexavalent dioxo cations of Np, Pu, and Am cocrystallize with UO 2(NO 3) 2∙ 6H 2O in near proportion with a simple reduction in temperature, while the lower valence states, An(III) and An(IV), are only slightly removed from solution. A separation of An(VI) species from An(III) ions by crystallization has been demonstrated, with an observed separation factor of 14. Separation of An(VI) species from key fission products, 95Zr,more » 95Nb, 137Cs, and 144Ce, has also been demonstrated by crystallization, with separation factors ranging from 6.5 to 71 in the absence of Am(VI), while in the presence of Am(VI), the separation factors were reduced to 0.99 7.7. One interesting observation is that Am(VI) shows increased stability in the cocrystallized form, with no reduction observed after 13 days, as opposed to in solution, in which >50% is reduced after only 10 days. The ability to cocrystallize and stabilize hexavalent actinides from solution, especially Am(VI), introduces a new separations approach that can be applied to closing the nuclear fuel cycle.« less

An experimental and modeling study of grain-scale uranium desorption from field-contaminated sediments and the potential influence of microporosity on mass-transfer

NASA Astrophysics Data System (ADS)

Stoliker, D.; Liu, C.; Kent, D. B.; Zachara, J. M.

2012-12-01

The aquifer below the 300-Area of the Hanford site (Richland, WA, USA) is plagued by a persistent plume of dissolved uranium (U(VI)) in excess of the Environmental Protection Agency drinking water maximum contamination level even after the removal of highly contaminated sediments. The aquifer sediments in the seasonally saturated lower vadose zone act as both a source and sink for uranium during stage changes in the nearby Columbia River. Diffusion limitation of uranium mass-transfer within these sediments has been cited as a potential cause of the plume's persistence. Equilibrium U(VI) sorption is a strong function of variable chemical conditions, especially carbonate, hydrogen, and uranyl ion activities. Field-contaminated sediments from the site require up to 1,000 hours to reach equilibrium in static batch reactors. Increases in U(VI) concentrations over longer time-scales result from changes in chemical conditions, which drive reactions with sediments that favor U(VI) desorption. Grain-scale U(VI) sorption/desorption rates are slow, likely owing to diffusion of U(VI) and other solutes through intra-granular pore domains. In order to improve understanding of the impact of intra-granular diffusion and chemical reactions controlling grain-scale U(VI) release, experiments were conducted on individual particle size fractions of a <8 mm composite of field-contaminated, lower vadose zone sediments. For each size fraction, equilibrium U(VI) sorption/desorption in static batch reactors was well-described by surface complexation models over a range of chemical conditions applicable to the field site. Desorption rates from individual size fractions in flow-through batch reactors, examined under a single set of constant chemical conditions with multiple stop-flow events, were similar for all size fractions <2 mm. Kinetic U(VI) desorption in flow-through batch reactors was modeled using a multi-rate surface complexation approach, where sorption/desorption rates were assumed to be proportional to the displacement from equilibrium and multiple diffusion domains were described with a two-parameter lognormal distribution of mass-transfer rate coefficients. Parameters describing mass transfer were the same for all size fractions <2 mm but differed for the largest (2-8 mm) size fraction. The evolution of pH, along with dissolved cation and carbonate concentrations, was modeled using equilibrium cation exchange, rate-limited calcite dissolution, aerobic respiration, and silica dissolution. Desorption and chemical reaction models calibrated with individual size fractions predicted U(VI) and chemical composition as a function of time for the bulk sediment sample. Volumes of pores less than 2.4 nm, quantified using nitrogen adsorption-desorption isotherms, were the same for all size fractions < 2 mm, nearly double that of the 2-8 mm size fraction. Similarity in the observed pore volumes and multi-rate mass-transfer parameters across all size fractions <2 mm suggest the importance of pores in this size class in controlling slow grain-scale U(VI) desorption rates. Models like these provide a means for testing the influence of grain-scale mass-transfer on the persistence of U(VI) plume at the site.

A multinational, multidisciplinary consensus for the diagnosis and management of spinal cord compression among patients with mucopolysaccharidosis VI.

PubMed

Solanki, Guirish A; Alden, Tord D; Burton, Barbara K; Giugliani, Roberto; Horovitz, Dafne D G; Jones, Simon A; Lampe, Christina; Martin, Kenneth W; Ryan, Maura E; Schaefer, Matthias K; Siddiqui, Aisha; White, Klane K; Harmatz, Paul

2012-09-01

Cervical cord compression is a sequela of mucopolysaccharidosis VI, a rare lysosomal storage disorder, and has devastating consequences. An international panel of orthopedic surgeons, neurosurgeons, anesthesiologists, neuroradiologists, metabolic pediatricians, and geneticists pooled their clinical expertise to codify recommendations for diagnosing, monitoring, and managing cervical cord compression; for surgical intervention criteria; and for best airway management practices during imaging or anesthesia. The recommendations offer ideal best practices but also attempt to recognize the worldwide spectrum of resource availability. Functional assessments and clinical neurological examinations remain the cornerstone for identification of early signs of myelopathy, but magnetic resonance imaging is the gold standard for identification of cervical cord compression. Difficult airways of MPS VI patients complicate the anesthetic and, thus, the surgical management of cervical cord compression. All patients with MPS VI require expert airway management during any surgical procedure. Neurophysiological monitoring of the MPS VI patient during complex spine or head and neck surgery is considered standard practice but should also be considered for other procedures performed with the patient under general anesthesia, depending on the length and type of the procedure. Surgical interventions may include cervical decompression, stabilization, or both. Specific techniques vary widely among surgeons. The onset, presentation, and rate of progression of cervical cord compression vary among patients with MPS VI. The availability of medical resources, the expertise and experience of members of the treatment team, and the standard treatment practices vary among centers of expertise. Referral to specialized, experienced MPS treatment centers should be considered for high-risk patients and those requiring complex procedures. Therefore, the key to optimal patient care is to implement best practices through meaningful communication among treatment team members at each center and among MPS VI specialists worldwide. Copyright © 2012 Elsevier Inc. All rights reserved.

Development of analytical procedures for the determination of hexavalent chromium in corrosion prevention coatings used in the automotive industry.

PubMed

Séby, F; Castetbon, A; Ortega, R; Guimon, C; Niveau, F; Barrois-Oudin, N; Garraud, H; Donard, O F X

2008-05-01

The European directive 2000/53/EC limits the use of Cr(VI) in vehicle manufacturing. Although a maximum of 2 g of Cr(VI) was authorised per vehicle for corrosion prevention coatings of key components, since July 2007 its use has been prohibited except for some particular applications. Therefore, the objective of this work was to develop direct analytical procedures for Cr(VI) determination in the different steel coatings used for screws. Instead of working directly with screws, the optimisation of the procedures was carried out with metallic plates homogeneously coated to improve the data comparability. Extraction of Cr(VI) from the metallic parts was performed by sonication. Two extraction solutions were tested: a direct water extraction solution used in standard protocols and an ammonium/ammonia buffer solution at pH 8.9. The extracts were further analysed for Cr speciation by high-performance liquid chromatography (HPLC) inductively coupled plasma (ICP) atomic emission spectrometry or HPLC ICP mass spectrometry depending on the concentration level. When possible, the coatings were also directly analysed by solid speciation techniques (X-ray photoelectron spectroscopy, XPS, and X-ray absorption near-edge structure, XANES) for validation of the results. Very good results between the different analytical approaches were obtained for the sample of coating made up of a heated paint containing Zn, Al and Cr when using the extracting buffer solution at pH 8.9. After a repeated four-step extraction procedure on the same portion test, taking into account the depth of the surface layer reached, good agreement with XPS and XANES results was obtained. In contrast, for the coatings composed of an alkaline Zn layer where Cr(VI) and Cr(III) are deposited, only the extraction procedure using water allowed the detection of Cr(VI). To elucidate the Cr(VI) reduction during extraction at pH 8.9, the reactivity of Cr(VI) towards different species of Zn generally present in the coatings (metallic Zn and zinc oxide) was studied. The results showed that metallic Zn rapidly reduces Cr(VI), whereas this reaction is less evident in the presence of zinc oxide. Water was then retained for coatings containing metallic Zn.

Versatile Cellulose-Based Carbon Aerogel for the Removal of Both Cationic and Anionic Metal Contaminants from Water.

PubMed

Alatalo, Sara-Maaria; Pileidis, Filoklis; Mäkilä, Ermei; Sevilla, Marta; Repo, Eveliina; Salonen, Jarno; Sillanpää, Mika; Titirici, Maria-Magdalena

2015-11-25

Hydrothermal carbonization of cellulose in the presence of the globular protein ovalbumin leads to the formation of nitrogen-doped carbon aerogel with a fibrillar continuous carbon network. The protein plays here a double role: (i) a natural source of nitrogen functionalities (2.1 wt %) and (ii) structural directing agent (S(BET) = 38 m(2)/g). The applicability in wastewater treatment, namely, for heavy metal removal, was examined through adsorption of Cr(VI) and Pb(II) ion solely and in a mixed bicomponent aqueous solutions. This cellulose-based carbogel shows an enhanced ability to remove both Cr(VI) (∼68 mg/g) and Pb(II) (∼240 mg/g) from the targeted solutions in comparison to other carbon materials reported in the literature. The presence of competing ions showed little effect on the adsorption efficiency toward Cr(VI) and Pb(II).

Kinetics and mechanism of diclofenac removal using ferrate(VI): roles of Fe3+, Fe2+, and Mn2.

PubMed

Zhao, Junfeng; Wang, Qun; Fu, Yongsheng; Peng, Bo; Zhou, Gaofeng

2018-06-01

In this study, the effect of Fe 3+ , Fe 2+ , and Mn 2+ dose, solution pH, reaction temperature, background water matrix (i.e., inorganic anions, cations, and natural organic matters (NOM)), and the kinetics and mechanism for the reaction system of Fe(VI)/Fe 3+ , Fe(VI)/Fe 2+ , and Fe(VI)/Mn 2+ were investigated systematically. Traces of Fe 3+ , Fe 2+ , and Mn 2+ promoted the DCF removal by Fe(VI) significantly. The pseudo-first-order rate constant (k obs ) of DCF increased with decreasing pH (9-6) and increasing temperature (10-30 °C) due to the gradually reduced stability and enhanced reactivity of Fe(VI). Cu 2+ and Zn 2+ ions evidently improved the DCF removal, while CO 3 2- restrained it. Besides, SO 4 2- , Cl - , NO 3 - , Mg 2+ , and Ca 2+ almost had no influence on the degradation of DCF by Fe(VI)/Fe 3+ , Fe(VI)/Fe 2+ , and Fe(VI)/Mn 2+ within the tested concentration. The addition of 5 or 20 mg L -1 NOM decreased the removal efficiency of DCF. Moreover, Fe 2 O 3 and Fe(OH) 3 , the by-products of Fe(VI), slightly inhibited the DCF removal, while α-FeOOH, another by-product of Fe(VI), showed no influence at pH 7. In addition, MnO 2 and MnO 4 - , the by-products of Mn 2+ , enhanced the DCF degradation due to catalysis and superposition of oxidation capacity, respectively. This study indicates that Fe 3+ and Fe 2+ promoted the DCF removal mainly via the self-catalysis for Fe(VI), and meanwhile, the catalysis of Mn 2+ and the effect of its by-products (i.e., MnO 2 and MnO 4 - ) contributed synchronously for DCF degradation. Graphical abstract ᅟ.

Simultaneous removal of Cu(II) and Cr(VI) by Mg-Al-Cl layered double hydroxide and mechanism insight.

PubMed

Yue, Xianyang; Liu, Weizhen; Chen, Zuliang; Lin, Zhang

2017-03-01

Mg-Al-Cl layered double hydroxide (Cl-LDH) was prepared to simultaneously remove Cu(II) and Cr(VI) from aqueous solution. The coexisting Cu(II) (20mg/L) and Cr(VI) (40mg/L) were completely removed within 30min by Cl-LDH in a dosage of 2.0g/L; the removal rate of Cu(II) was accelerated in the presence of Cr(VI). Moreover, compared with the adsorption of single Cu(II) or Cr(VI), the adsorption capacities of Cl-LDH for Cu(II) and Cr(VI) can be improved by 81.05% and 49.56%, respectively, in the case of coexisting Cu(II) (200mg/L) and Cr(VI) (400mg/L). The affecting factors (such as solution initial pH, adsorbent dosage, and contact time) have been systematically investigated. Besides, the changes of pH values and the concentrations of Mg 2+ and Al 3+ in relevant solutions were monitored. To get the underlying mechanism, the Cl-LDH samples before and after adsorption were thoroughly characterized by X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. On the basis of these analyses, a possible mechanism was proposed. The coadsorption process involves anion exchange of Cr(VI) with Cl - in Cl-LDH interlayer, isomorphic substitution of Mg 2+ with Cu 2+ , formation of Cu 2 Cl(OH) 3 precipitation, and the adsorption of Cr(VI) by Cu 2 Cl(OH) 3 . This work provides a new insight into simultaneous removal of heavy metal cations and anions from wastewater by Cl-LDH. Copyright © 2016. Published by Elsevier B.V.

Simultaneous determination of Cr(III) and Cr(VI) in tannery wastewater using low pressure ion chromatography combined with flow injection spectrophotometry

NASA Astrophysics Data System (ADS)

Chen, Shujuan; Zhang, Xinshen; Yu, Lingyun; Wang, Li; Li, Hui

2012-03-01

Trivalent and hexavalent chromium have been successfully separated and determined using low pressure ion chromatography combined with flow injection spectrophotometric analysis (LPIC-FIA). A column packed with crosslinking starch microspheres was used for on-line separation of Cr(III) from Cr(VI) in a flow-injection system because of its absorptive effect on Cr(III). To determine the concentration of Cr(III) and Cr(VI) in samples, we used 3.0 mmol/L nitric acid to elute adsorbed Cr(III) from the column and then used ceric sulfate-sulfuric acid as oxidant to convert all Cr(III) into Cr(VI). Then, Cr(VI) directly came from the samples and Cr(VI) came from Cr(III) successively formed a amaranthine complex with diphenycarbazide and the complex shows a maximum absorption at 530 nm. Analytical parameters including the concentration of eluent and oxidant solution, oxidizing temperature, length of oxidizing reaction coil, reaction coil and injection coil, interfering effects, etc., were optimized. The limit of detection was 1.25 μg/L for Cr(VI) and 3.76 μg/L for Cr(III). The linear relationship between absorption with the concentration of Cr(VI) and Cr(III) was 0.001-1.000 mg/L and 0.030-1.000 mg/L with correlation coefficients of 0.9995 and 0.9994, respectively. The relative standard deviation of Cr(VI) and Cr(III) was 1.21% and 1.66%, respectively (n = 10). Major cations and anions did not show any interference. We validated this method through certified reference materials and through measuring the recovery in tannery wastewater.

Suitability of II-VI semiconductors for photonic applications: common-anion versus common-cation superlattices

NASA Astrophysics Data System (ADS)

Tit, Nacir

2003-12-01

Based on the sp3s tight-binding method, the electronic band strcutures of both common-anion and common-cation II-VI superlattices (SLs) are investigated. As models, we took for the former the case of CdTe/ZnTe(001) SLs where the common anion is confirmed to yield a vanishing or a small valence-band offset (VBO) and the biaxial strain, of course, contributes in the valence-band splittings and yield type-I SLs in most of the studied cases. Whereas, we tok as a second model two different SLs: the ZnS/ZnSe(001) and ZnSe/ZnTe(001) SLs. We have confirmed that the common-cation SLs cannot have a vanishing conduction-band offsets (CBO), as speculated, but rather the CBO could be as large as the VBO. The biaxial strain, again, can participate here in the formation of the band offsets and yield either type-I SLs, as in the case of the ZnS/ZnSe, or type-II SLs, as in the case of ZnSe/ZnTe. Moreover, the reason why some type-II SLs, such as ZnSe/ZnTe(001), could be useful as photonic devices is explained by the tendency of the carriers to confine near the interface as a result of a strong photoluminenscence data and conclusions have been drawn about the strain morpholgy and the structural and optical qualities of the experimental samples.

Effects of gamma-sterilization on the physico-chemical properties of natural sediments

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

Bank, Tracy L.; Kukkadapu, Ravi K.; Madden, Andrew S.

2008-06-30

A series of experiments were completed to determine the effects of soil sterilization on various soil chemical properties including U(VI) sorption, soil pH, natural organic matter (NOM), cation exchange capacity (CEC), and iron oxidation state. Soils under investigation were a saprolitic sequence of interbedded weathered shale and limestone collected from the Oak Ridge Reservation (ORR). Sediments were sterilized by either steam sterilization at 121oC or by γ-irradiation using a cobalt-60 source. Subsamples of sediments were pretreated with dithionate-citrate-bicarbonate (DCB) and/or H2O2 to remove reducible Fe(III) oxides and NOM. Results from aerobic U(VI) sorption experiments indicated that γ-sterilized sediments sorbed moremore » U(VI) compared to non-sterile sediments. Results from sorption experiments completed using DCB and H2O2-treated samples indicated that the iron oxide and NOM fractions of the sediment accounted for the majority of U(VI) sorption and that γ-irradiation of these phases resulted in increased sorption of U(VI). Mössbauer spectra of γ-sterilized sedimentsdisplayed a decrease in the amount of ferric iron associated with goethite and a small increase in the amount of reduced iron in silicate minerals compared to spectra from non-sterile samples. Our results suggest that sterilization by γ-irradiation induced iron reduction that may have increased sorption of U(VI) on these sediments.« less

Keplerate cluster (Mo-132) mediated electrostatic assembly of nanoparticles.

PubMed

Gooch, Jonathan; Jalan, Abhishek A; Jones, Stephanie; Hine, Corey R; Alam, Rabeka; Garai, Somenath; Maye, Mathew M; Müller, Achim; Zubieta, Jon

2014-10-15

The electrostatic assembly between a series of differently charged Mo-132-type Keplerates present in the compounds (NH4)42[{(Mo(VI))Mo(VI)5O21(H2O)6}12 {Mo(V)2O4(CH3COO)}30].ca. {300 H2O+10 CH3COONH4} (Mo-132a), (NH4)72-n[{(H2O)81-n+(NH4)n} {(Mo(VI))Mo(VI)5O21(H2O)6}12 {Mo(V)2O4(SO4)}30].ca. 200 H2O (Mo-132b), and Na10(NH4)62[{(Mo(VI))Mo(VI)5O21(H2O)6}12 {Mo(V)2O4(HPO4)}30]. ca. {300H2O+2Na(+)+2NH4(+)+4H2PO4(-)} (Mo-132c) with cationic gold nanoparticles (AuNPs) was investigated for the first time. The rapid electrostatic assembly from nanoscopic entities to micron scale aggregates was observed upon precipitation, which closely matched the point of aggregate electroneutrality. Successful assembly was demonstrated using UV-vis, DLS, TEM, and zeta-potential analysis. Results indicate that the point at which precipitation occurs is related to charge balance or electroneutrality, and that counterions at both the Mo-132 and AuNP play a significant role in assembly. Copyright © 2014 Elsevier Inc. All rights reserved.

32 CFR 2003.6 - Voting (Article VI).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 32 National Defense 6 2014-07-01 2014-07-01 false Voting (Article VI). 2003.6 Section 2003.6 National Defense Other Regulations Relating to National Defense INFORMATION SECURITY OVERSIGHT OFFICE...) BYLAWS, RULES, AND APPEAL PROCEDURES Bylaws § 2003.6 Voting (Article VI). (a) Motions. When the Panel is...

32 CFR 2003.6 - Voting (Article VI).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 6 2013-07-01 2013-07-01 false Voting (Article VI). 2003.6 Section 2003.6 National Defense Other Regulations Relating to National Defense INFORMATION SECURITY OVERSIGHT OFFICE...) BYLAWS, RULES, AND APPEAL PROCEDURES Bylaws § 2003.6 Voting (Article VI). (a) Motions. When the Panel is...

A Laboratory Procedure for the Reduction of Chromium(VI) to Chromium(III).

ERIC Educational Resources Information Center

Lunn, George; Sansone, Eric B.

1989-01-01

Chromium(VI) compounds are classified as oxidizers and must be specially packaged and transported for disposal while Cr(III) compounds are considered nonoxidizers. A process which reduces Cr(VI) to Cr(III) by adding sodium metabisulfite followed by neutralization with magnesium hydroxide is explored. (MVL)

Transcatheter Aortic Valve-in-Valve Procedure in Patients with Bioprosthetic Structural Valve Deterioration

PubMed Central

Reul, Ross M.; Ramchandani, Mahesh K.; Reardon, Michael J.

2017-01-01

Surgical aortic valve replacement is the gold standard procedure to treat patients with severe, symptomatic aortic valve stenosis or insufficiency. Bioprosthetic valves are used for surgical aortic valve replacement with a much greater prevalence than mechanical valves. However, bioprosthetic valves may fail over time because of structural valve deterioration; this often requires intervention due to severe bioprosthetic valve stenosis or regurgitation or a combination of both. In select patients, transcatheter aortic valve replacement is an alternative to surgical aortic valve replacement. Transcatheter valve-in-valve (ViV) replacement is performed by implanting a transcatheter heart valve within a failing bioprosthetic valve. The transcatheter ViV operation is a less invasive procedure compared with reoperative surgical aortic valve replacement, but it has been associated with specific complications and requires extensive preoperative work-up and planning by the heart team. Data from experimental studies and analyses of results from clinical procedures have led to strategies to improve outcomes of these procedures. The type, size, and implant position of the transcatheter valve can be optimized for individual patients with knowledge of detailed dimensions of the surgical valve and radiographic and echocardiographic measurements of the patient's anatomy. Understanding the complexities of the ViV procedure can lead surgeons to make choices during the original surgical valve implantation that can make a future ViV operation more technically feasible years before it is required. PMID:29743998

The Oxidation of Secondary Alcohols with Cr(VI): A Spectrophotometric Method.

ERIC Educational Resources Information Center

Mason, Timothy J.; And Others

1985-01-01

Background information, procedures, and typical results are provided for an experiment in which spectrophotometry is used to examine the oxidation of secondary alcohols using chromium (VI). The overall change in oxidation state of chromium during the reaction is VI to III, corresponding to the familiar color change from orange to green. (JN)

Structure, Kinetics, and Thermodynamics of the Aqueous Uranyl(VI) Cation

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

Kerisit, Sebastien N.; Liu, Chongxuan

2013-08-20

Molecular simulation techniques are employed to gain insights into the structural, kinetic, and thermodynamic properties of the uranyl(VI) cation (UO22+) in aqueous solution. The simulations make use of an atomistic potential model (force field) derived in this work and based on the model of Guilbaud and Wipff (Guilbaud, P.; Wipff, G. J. Mol. Struct. (THEOCHEM) 1996, 366, 55-63). Reactive flux and thermodynamic integration calculations show that the derived potential model yields predictions for the water exchange rate and free energy of hydration, respectively, that are in agreement with experimental data. The water binding energies, hydration shell structure, and self-diffusion coefficientmore » are also calculated and discussed. Finally, a combination of metadynamics and transition path sampling simulations is employed to probe the mechanisms of water exchange reactions in the first hydration shell of the uranyl ion. These atomistic simulations indicate, based on two-dimensional free energy surfaces, that water exchanges follow an associative interchange mechanism. The nature and structure of the water exchange transition states are also determined. The improved potential model is expected to lead to more accurate predictions of uranyl adsorption energies at mineral surfaces using potential-based molecular dynamics simulations.« less

An Improved Qualitative Analysis Procedure for Aluminum Subgroup Cations.

ERIC Educational Resources Information Center

Kistner, C. R.; Robinson, Patricia J.

1983-01-01

Describes a procedure for the qualitative analysis of aluminum subgroup cations designed to avoid failure to obtain lead or barium chromate precipitates or failure to report aluminum hydroxide when present (due to staining). Provides a flow chart and step-by-step explanation for the new procedure, indicating significantly improved student results.…

Enhanced removal of Se(VI) from water via pre-corrosion of zero-valent iron using H2O2/HCl: Effect of solution chemistry and mechanism investigation.

PubMed

Shan, Chao; Chen, Jiajia; Yang, Zhe; Jia, Huichao; Guan, Xiaohong; Zhang, Weiming; Pan, Bingcai

2018-04-15

Although the removal of Se(VI) from water by using zero-valent iron (ZVI) is a promising method, passivation of ZVI severely inhibits its performance. To overcome such issue, we proposed an efficient technique to enhance Se(VI) removal via pre-corrosion of ZVI with H 2 O 2 /HCl in a short time (15 min). The resultant pcZVI suspension was weakly acidic (pH 4.56) and contained abundant aqueous Fe 2+ . 57 Fe Mössbauer spectroscopy showed that pcZVI mainly consisted of Fe 0 (66.2%), hydrated ferric oxide (26.3%), and Fe 3 O 4 (7.5%). Efficient removal of Se(VI) from sulfate-rich solution was achieved by pcZVI compared with ZVI (in the absence and presence of H 2 O 2 ) and acid-pretreated ZVI. Moreover, the efficient removal of Se(VI) by pcZVI sustained over a broad pH range (3-9) due to its strong buffering power. The presence of chloride, carbonate, nitrate, and common cations (Na + , K + , Ca 2+ , and Mg 2+ ) posed negligible influence on the removal of Se(VI) by pcZVI, while the inhibitory effect induced by sulfate, silicate, and phosphate indicated the significance of Se(VI) adsorption as a prerequisite step for its removal. The consumption of aqueous Fe 2+ was associated with Se(VI) removal, and X-ray absorption near edge structure revealed that the main pathway for Se(VI) removal by pcZVI was a stepwise reduction of Se(VI) to Se(IV) and then Se 0 as the dominant final state (78.2%). Moreover, higher electron selectivity of pcZVI was attributed to the enhanced enrichment of Se oxyanions prior to their reduction. Copyright © 2018 Elsevier Ltd. All rights reserved.

Synthesis, crystal structure and magnetic properties of a new B-site ordered double perovskite Sr{sub 2}CuIrO{sub 6}

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

Vasala, Sami; Yamauchi, Hisao; Karppinen, Maarit, E-mail: maarit.karppinen@aalto.fi

2014-12-15

Here we synthesize and characterize a new double-perovskite oxide Sr{sub 2}CuIrO{sub 6}. The synthesis requires the use of high oxygen pressure to stabilize the VI oxidation state of iridium. The compound has a tetragonally-distorted crystal structure due to the Jahn–Teller active Cu{sup II} ion, and a high degree of B-site cation order. Magnetic transition is apparent at 15 K, but the zero-field-cooled and field-cooled susceptibilities diverge below this temperature. The high degree of cation order would exclude the possibility of a typical spin-glass, indicating that the divergence is probably due to a frustration of the magnetic interactions between Cu andmore » Ir, with a high frustration factor of f≈25. - Graphical abstract: A new member of the A{sub 2}B′B″O{sub 6} double-perovskite family with JT-active Cu{sup II} at the B′ site and Ir{sup VI} at the B″ site is synthesized through high pressure synthesis and characterized for the structural and magnetic properties. - Highlights: • New member of the A{sub 2}CuB″O{sub 6} double-perovskite family is synthesized with B″=Ir. • Stabilization of Ir{sup VI} requires the use of high oxygen pressure synthesis. • Crystal structure is tetragonally distorted due to JT-active Cu{sup II}. • Divergence of ZFC and FC curves is seen below the T{sub N} of 15 K. • This is presumably due to a frustration effect.« less

Manual of Procedures for Applying for Funding under Title VI, Part B--Education of the Handicapped Act. P.L. 91-230 as Amended by P.L. 93-320, P.L. 94-142 and P.L. 99-457. EHA, Title VI, Part B--Third Year of a Three-Year Plan, 1988-89. ECIA, Chapter 1, Handicapped Preschool Grant Program.

ERIC Educational Resources Information Center

North Carolina State Dept. of Public Instruction, Raleigh. Div. for Exceptional Children.

The manual presents procedures for local school districts in North Carolina applying for federal funding under Title VI, Part B, Education of the Handicapped Act, as amended by Public Laws 93-320, 94-142, and 99-457. The first chapter gives instructions for submission of amendments for the third year of the 3-year plan and includes an introduction…

Adsorption behavior comparison of trivalent and hexavalent chromium on biochar derived from municipal sludge.

PubMed

Chen, Tan; Zhou, Zeyu; Xu, Sai; Wang, Hongtao; Lu, Wenjing

2015-08-01

In this work, static equilibrium experiments were conducted to distinguish the adsorption performance between the two valence states of chromium on biochar derived from municipal sludge. The removal capacity of Cr(VI) is lower than 7mg/g at the initial chromium concentration range of 50-200mg/L, whereas that of Cr(III) higher than 20mg/g. It indicates that Cr(III) is much easier to be stabilized than Cr(VI). No significant changes in the biochar surface functional groups are observed before and after the adsorption equilibrium, demonstrating the poor contribution of organic matter in chromium adsorption. The main mechanism of heavy metal adsorption by biochar involves (1) surface precipitation through pH increase caused by biochar buffer ability, and (2) exchange between cations in solution (Cd(2+)) and in biochar matrix (e.g. Ca(2+) and Mg(2+)). The reduction of Cr(VI) to Cr(III) is necessary to improve removal efficiency of chromium. Copyright © 2015 Elsevier Ltd. All rights reserved.

Application of a surfactant-assisted dispersive liquid-liquid microextraction method along with central composite design for micro-volume based spectrophotometric determination of low level of Cr(VI) ions in aquatic samples.

PubMed

Sobhi, Hamid Reza; Azadikhah, Efat; Behbahani, Mohammad; Esrafili, Ali; Ghambarian, Mahnaz

2018-05-09

A fast, simple, low cost surfactant-assisted dispersive liquid-liquid microextraction method along with central composite design for the determination of low level of Cr(VI) ions in several aquatic samples has been developed. Initially, Cr(VI) ions present in the aqueous sample were readily reacted with 1,5‑diphenylcarbazide (DPC) in acidic medium through complexation. Sodium dodecyl sulfate (SDS), as an anionic surfactant, was then employed as an ion-pair agent to convert the cationic complex into the neutral one. Following on, the whole aqueous phase underwent a dispersive liquid-liquid microextraction (DLLME) leading to the transfer of the neutral complex into the fine droplet of organic extraction phase. A micro-volume spectrophotometer was used to determine Cr(VI) concentrations. Under the optimized conditions predicted by the statistical design, the limit of quantification (LOQ) obtained was reported to be 5.0 μg/L, and the calibration curve was linear over the concentration range of 5-100 μg/L. Finally, the method was successfully implemented for the determination of low levels of Cr(VI) ions in various real aquatic samples and the accuracies fell within the range of 83-102%, while the precision varied in the span of 1.7-5.2%. Copyright © 2018. Published by Elsevier B.V.

Examination of Cr(VI) treatment by zero-valent iron using in situ, real-time X-ray absorption spectroscopy and Cr isotope measurements

NASA Astrophysics Data System (ADS)

Jamieson-Hanes, Julia H.; Lentz, Adam M.; Amos, Richard T.; Ptacek, Carol J.; Blowes, David W.

2014-10-01

A series of replicate flow-through cell experiments was conducted to characterize Cr isotope fractionation during Cr(VI) treatment by granular zero-valent iron (ZVI). Synthetic groundwater containing 50 mg L-1 Cr(VI) was pumped upward through a custom-made cell packed with ZVI under anaerobic conditions. The geochemical evolution of the system was monitored using pH and redox measurements, while aqueous effluent samples were retained for analysis of cations and Cr isotopes. Real-time, in situ X-ray absorption near edge structure (XANES) spectroscopy collected via a Kapton® window in the cell provided additional information on the speciation of the reaction products. Increases in δ53Cr values corresponding to decreases in Cr(VI) concentration suggested the occurrence of redox processes. Spectroscopic results correlated well with the isotope data, indicating reduction of Cr(VI) to Cr(III). The isotope data did not appear to follow a single trend. A two-stage system was proposed to explain the complex isotope trend, where the rapid Cr removal was associated with very little fractionation (ε = -0.2‰), whereas slower removal was associated with a greater degree of fractionation (ε = -1.2‰ to -1.5‰). Reactive transport modeling was used to quantify distinct isotope fractionation values (ε), differentiated by a significant change in the Cr removal rate.

Development of an algorithm to plan and simulate a new interventional procedure.

PubMed

Fujita, Buntaro; Kütting, Maximilian; Scholtz, Smita; Utzenrath, Marc; Hakim-Meibodi, Kavous; Paluszkiewicz, Lech; Schmitz, Christoph; Börgermann, Jochen; Gummert, Jan; Steinseifer, Ulrich; Ensminger, Stephan

2015-07-01

The number of implanted biological valves for treatment of valvular heart disease is growing and a percentage of these patients will eventually undergo a transcatheter valve-in-valve (ViV) procedure. Some of these patients will represent challenging cases. The aim of this study was to develop a feasible algorithm to plan and in vitro simulate a new interventional procedure to improve patient outcome. In addition to standard diagnostic routine, our algorithm includes 3D printing of the annulus, hydrodynamic measurements and high-speed analysis of leaflet kinematics after simulation of the procedure in different prosthesis positions as well as X-ray imaging of the most suitable valve position to create a 'blueprint' for the patient procedure. This algorithm was developed for a patient with a degenerated Perceval aortic sutureless prosthesis requiring a ViV procedure. Different ViV procedures were assessed in the algorithm and based on these results the best option for the patient was chosen. The actual procedure went exactly as planned with help of this algorithm. Here we have developed a new technically feasible algorithm simulating important aspects of a novel interventional procedure prior to the actual procedure. This algorithm can be applied to virtually all patients requiring a novel interventional procedure to help identify risks and find optimal parameters for prosthesis selection and placement in order to maximize safety for the patient. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

A first principles investigation of electron transfer between Fe(II) and U(VI) on insulating Al- vs. semiconducting Fe-oxide surfaces via the proximity effect

NASA Astrophysics Data System (ADS)

Taylor, S. D.; Marcano, M. C.; Becker, U.

2017-01-01

This study investigates how the intrinsic chemical and electronic properties of mineral surfaces and their associated electron transfer (ET) pathways influence the reduction of U(VI) by surface-associated Fe(II). Density functional theory (DFT), including the Hubbard U correction to the exchange-correlation functional, was used to investigate sorption/redox reactions and ET mechanisms between Fe(II) and U(VI) coadsorbed on isostructural, periodic (0 0 1) surfaces of the insulator corundum (α-Al2O3) vs. the semiconductor hematite (α-Fe2O3). Furthermore, the coadsorbed Fe(II) and U(VI) ions are spatially separated from one another on the surfaces (⩾5.9 Å) to observe whether electronic-coupling through the semiconducting hematite surface facilitates ET between the adsorbates, a phenomenon known as the proximity effect. The calculations show that the different chemical and electronic properties between the isostructural corundum and hematite (0 0 1) surfaces lead to considerably different ET mechanisms between Fe(II) and U(VI). ET on the insulating corundum (0 0 1) surface is limited by the adsorbates' structural configuration. When Fe(II) and U(VI) are spatially separated and do not directly interact with one another (e.g. via an inner-sphere complex), U(VI) reduction by Fe(II) cannot occur as there is no physical pathway enabling ET between the adsorbates. In contrast to the insulating corundum (0 0 1) surface, the hematite (0 0 1) surface can potentially participate in ET reactions due to the high number of electron acceptor sites from the Fe d-states near the Fermi level at the hematite surface. The adsorption of Fe(II) also introduces d-states near the Fermi level as well as shifts unoccupied d-states of the Fe cations at the hematite surface to lower energies, making the surface more conductive. In turn, electronic coupling through the surface can link the spatially separated adsorbates to one another and provide distinct ET pathways for an electron from Fe(II) to travel through the hematite surface and reach U(VI). The progression and extent of ET occurring on the semiconducting hematite (0 0 1) surface via the proximity effect depends on the electronic properties of the surface. ET between the spatially separated U(VI) and Fe(II) occurs most readily when orbitals between the Fe and U adsorbates overlap with those of neighboring O and Fe ions at the hematite surface, as shown by calculations without the Hubbard U correction. Analyses of the spins densities confirm that the U and Fe adsorbates were reduced and oxidized, respectively, (acquiring 0.33 μB and 0.11-0.20 μB, respectively), while Fe cations at the hematite surface were reduced (losing ⩽0.6 μB). If electrons are highly localized, the amount of orbital mixing and electronic coupling through the hematite surface decreases and in turn leads to a lower degree of spin transfer, as predicted by calculations with the Hubbard U correction. Thus, the proximity effect is a potential mechanism on semiconducting surfaces facilitating surface-mediated redox reactions, although its significance varies depending on the electronic properties and subsequent charge-carrying ability of the surface. These results provide insight into ET pathways and mechanisms on insulating Al- and semiconducting Fe oxide surfaces influencing the reduction U(VI) by Fe(II) that may subsequently limit uranium's transport in the subsurface.

Department of Defense Manpower Requirements Report: Fy 1993

DTIC Science & Technology

1992-02-01

retention programs are dealing effectively with the available strength shortfall; however, NOS qualifi- cation (MOSQ) remains the primary readiness inhibitor ...n r- nLn P4 r- 0 .a. W 43) 0%~~~ aa a aa a aa a VU 4343 Uf .ai 0 a 4 .44 0 ~ ~ ~ ~ ~ ~ ~ ~ ~ .’ 0n 󈧄% Or - 0 - o% e n 5 ac vi𔃼 %oc 4I oa jL nc "P

Stabilization of cationic and anionic metal species in contaminated soils using sludge-derived biochar.

PubMed

Fang, Shen'en; Tsang, Daniel C W; Zhou, Fengsha; Zhang, Weihua; Qiu, Rongliang

2016-04-01

Currently, sludge pyrolysis has been considered as a promising technology to solve disposal problem of municipal sewage sludge, recover sludge heating value, sequester carbon and replenish nutrients in farmland soils. The resultant sludge-derived biochar (SDBC) is potentially an excellent stabilizing agent for metal species. This study applied the SDBC into four soils that had been contaminated in field with cationic Pb(II) and Cd(II)/Ni(II), and anionic Cr(VI) and As(III), respectively. The performance of metal stabilization under various operational and environmental conditions was evaluated with acid batch extraction and column leaching tests. Results indicated the SDBC could effectively stabilize these metals, which was favored by elevated temperature and longer aging. Periodic temperature decrease from 45 to 4 °C resulted in the release of immobilized Cr(VI) and As(III) but not Pb(II). However, a longer aging time offset such metal remobilization. This was possibly because more Pb was strongly bound and even formed stable precipitates, as shown by XRD and sequential extraction results. With increasing time, Cr(VI) was sorbed and partly reduced to Cr(III), while immobilized As(III) was co-oxidized to As(V) as indicated by XPS spectra. Column tests revealed that adding SDBC as a separate layer was unfavorable because the concentrated Cd(II) and Ni(II) in localized positions increased the peak levels of metal release under continuous acid leaching. In contrast, uniformly mixed SDBC could effectively delay the metal breakthrough and reduce their released amounts. Yet, a long-term monitoring may be required for evaluating the potential leaching risks and bioavailability/toxicity of these immobilized and transformed species in the SDBC-amended soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

Neutral ligand TIPA-based two 2D metal-organic frameworks: ultrahigh selectivity of C2H2/CH4 and efficient sensing and sorption of Cr(vi ).

PubMed

Fu, Hong-Ru; Zhao, Ying; Zhou, Zhan; Yang, Xiao-Gang; Ma, Lu-Fang

2018-03-12

One neutral tripodal semi-rigidity ligand tri(4-imidazolylphenyl)amine (TIPA) with excellent hole-transfer nature, was selected as a linker to construct MOFs. Two two-dimensional (2D) microporous metal-organic frameworks (MOFs) were synthesized solvothermally: [Ni(TIPA)(COO - ) 2 (H 2 O)]·2(DMF)2(H 2 O) (1) and [Cd(TIPA) 2 (ClO 4 - ) 2 ]·(DMF)3(H 2 O) (2). Compound 1 incorporated carboxylic groups into the channel and exhibited the high capacity of light hydrocarbons as well as the remarkable selectivity of C 2 H 2 /CH 4 . The value is in excess of 100 at room temperature, which is the highest value reported to date. Compound 2, as a cationic framework with high water stability, was not only applied as a sensor, displaying the ultrahigh sensitivity against Cr 2 O 7 2- with a detection limit as low as 8 ppb, but also possessed excellent Cr(vi) sorption with good repeatability in aqueous solution. This study provides an efficient strategy to design cationic MOFs for the selective separation of light hydrocarbons and the sensing and trapping of toxic chromate for the purification of water.

National Economic Development Procedures Manual - Recreation. Volume 2. A Guide for Using the Contingent Value Methodology in Recreation Studies,

DTIC Science & Technology

1986-03-01

Directly from Sample Bid VI-16 Example 3 VI-16 Determining the Zero Price Qiantity Demanded VI-26 Summary VI -31 CHAPrER VII, THE DETERMINATION OF NED...While the standard deviation and variance are absolute measures of dispersion, a relative measure of dispersion can also be computed. This measure is...refers to the closeness of fit between the estimates obtained from Zli e and the true population value. The only way of being absolutely i: o-.iat the

High-Pressure Phase Relations and Crystal Structures of Postspinel Phases in MgV2O4, FeV2O4, and MnCr2O4: Crystal Chemistry of AB2O4 Postspinel Compounds.

PubMed

Ishii, Takayuki; Sakai, Tsubasa; Kojitani, Hiroshi; Mori, Daisuke; Inaguma, Yoshiyuki; Matsushita, Yoshitaka; Yamaura, Kazunari; Akaogi, Masaki

2018-06-04

We have investigated high-pressure, high-temperature phase transitions of spinel (Sp)-type MgV 2 O 4 , FeV 2 O 4 , and MnCr 2 O 4 . At 1200-1800 °C, MgV 2 O 4 Sp decomposes at 4-7 GPa into a phase assemblage of MgO periclase + corundum (Cor)-type V 2 O 3 , and they react at 10-15 GPa to form a phase with a calcium titanite (CT)-type structure. FeV 2 O 4 Sp transforms to CT-type FeV 2 O 4 at 12 GPa via decomposition phases of FeO wüstite + Cor-type V 2 O 3 . MnCr 2 O 4 Sp directly transforms to the calcium ferrite (CF)-structured phase at 10 GPa and 1000-1400 °C. Rietveld refinements of CT-type MgV 2 O 4 and FeV 2 O 4 and CF-type MnCr 2 O 4 confirm that both the CT- and CF-type structures have frameworks formed by double chains of edge-shared B 3+ O 6 octahedra (B 3+ = V 3+ and Cr 3+ ) running parallel to one of orthorhombic cell axes. A relatively large A 2+ cation (A 2+ = Mg 2+ , Fe 2+ , and Mn 2+ ) occupies a tunnel-shaped space formed by corner-sharing of four double chains. Effective coordination numbers calculated from eight neighboring oxygen-A 2+ cation distances of CT-type MgV 2 O 4 and FeV 2 O 4 and CF-type MnCr 2 O 4 are 5.50, 5.16, and 7.52, respectively. This implies that the CT- and CF-type structures practically have trigonal prism (six-coordinated) and bicapped trigonal prism (eight-coordinated) sites for the A 2+ cations, respectively. A relationship between cation sizes of VIII A 2+ and VI B 3+ and crystal structures (CF- and CT-types) of A 2+ B 2 3+ O 4 is discussed using the above new data and available previous data of the postspinel phases. We found that CF-type A 2+ B 2 3+ O 4 crystallize in wide ionic radius ranges of 0.9-1.4 Å for VIII A 2+ and 0.55-1.1 Å for VI B 3+ , whereas CT-type phases crystallize in very narrow ionic radius ranges of ∼0.9 Å for VIII A 2+ and 0.6-0.65 Å for VI B 3+ . This would be attributed to the fact that the tunnel space of CT-type structure is geometrically less flexible due to the smaller coordination number for A 2+ cation than that of CF-type.

Determination of Chromium(III), Chromium(VI), and Chromium(III) acetylacetonate in water by ion-exchange disk extraction/metal furnace atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Kamakura, Nao; Inui, Tetsuo; Kitano, Masaru; Nakamura, Toshihiro

A new method for the separate determination of Chromium(III) (Cr(III)), Chromium(VI) (Cr(VI)), and Cr(III) acetylacetonate (Cr(acac)3) in water was developed using a cation-exchange extraction disk (CED) and an anion-exchange extraction disk (AED) combined with metal furnace atomic absorption spectrometry (MFAAS). A 100-mL water sample was adjusted to pH 5.6 and passed through the CED placed on the AED. Cr(acac)3 and Cr(III) were adsorbed on the CED, and Cr(VI) was adsorbed on the AED. The adsorbed Cr(acac)3 was eluted with 50 mL of carbon tetrachloride, followed by the elution of Cr(III) with 50 mL of 3 mol L- 1 nitric acid. Cr(VI) was eluted with 50 mL of 3 mol L- 1 nitric acid. The chemical species of Cr eluted from the CED with carbon tetrachloride was identified as Cr(acac)3 using infrared spectroscopy. The eluate of Cr(acac)3 was diluted to 100 mL with carbon tetrachloride, and those of Cr(III) and Cr(VI) were diluted to 100 mL with deionized water. All of the solutions were subsequently analyzed by MFAAS. The calibration curve for the Cr(acac)3 aqueous solutions exhibited good linearity in the range of 0.1 to 1 ng. The detection limit of Cr, which corresponded to three times the standard deviation (n = 10) of the blank values, was 20 pg. The recovery test for Cr(III), Cr(VI), and Cr(acac)3 exhibited desirable results (96.0%-107%) when 5 μg of each species (50 μg L- 1) was added to 100 mL water samples (i.e., tap water, rainwater, and bottled drinking water). In a humic acid solution, Cr(acac)3 was quantitatively recovered (103%), but Cr(III) and Cr(VI) exhibited poor recoveries (i.e., 84.8% and 78.4%, respectively).

28 CFR 42.415 - Federal agency title VI enforcement plan.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 28 Judicial Administration 1 2014-07-01 2014-07-01 false Federal agency title VI enforcement plan. 42.415 Section 42.415 Judicial Administration DEPARTMENT OF JUSTICE NONDISCRIMINATION; EQUAL EMPLOYMENT OPPORTUNITY; POLICIES AND PROCEDURES Coordination of Enforcement of Non-discrimination in...

High-pressure compressibility and vibrational properties of (Ca,Mn)CO 3

DOE PAGES

Liu, Jin; Caracas, Razvan; Fan, Dawei; ...

2016-12-01

Knowledge of potential carbon carriers such as carbonates is critical for our understanding of the deep-carbon cycle and related geological processes within the planet. Here we investigated the high-pressure behavior of (Ca,Mn)CO 3 up to 75 GPa by synchrotron single-crystal X-ray diffraction, laser Raman spectroscopy, and theoretical calculations. MnCO 3-rich carbonate underwent a structural phase transition from the CaCO 3-I structure into the CaCO 3-VI structure at 45–48 GPa, while CaCO 3-rich carbonate transformed into CaCO 3-III and CaCO 3-VI at approximately 2 and 15 GPa, respectively. The equation of state and vibrational properties of MnCO 3-rich and CaCO 3-richmore » carbonates changed dramatically across the phase transition. The CaCO 3-VI-structured CaCO 3-rich and MnCO 3-rich carbonates were stable at room temperature up to at least 53 and 75 GPa, respectively. In conclusion, the addition of smaller cations (e.g., Mn 2+, Mg 2+, and Fe 2+) can enlarge the stability field of the CaCO 3-I phase as well as increase the pressure of the structural transition into the CaCO 3-VI phase.« less

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

Wang, Yan; Pan, Cheng-Ling; Xiao, Li-Na

Three new supramolecular compounds based on triethylenediamine and different polyoxometalates [W{sup VI}{sub 3}V{sup V}{sub 3}O{sub 19}H]{l_brace}[Cu(HDABCO)]{sub 2}(H{sub 2}O){r_brace} (1), [P{sub 2}Mo{sup VI}{sub 18}O{sub 62}][HDABCO]{sub 2}[H{sub 2}DABCO]{sub 2}.12 H{sub 2}O (2) and [Mo{sup VI}{sub 7.5}W{sup VI}{sub 0.5}O{sub 27}][Cu(HDABCO)]{sub 2}.2 H{sub 3}O.2 H{sub 2}O (3) (DABCO=triethylenediamine) have been synthesized hydrothermally and characterized by IR, TG, XPS and X-ray diffraction analyses. Crystal structure analyses reveal that compound 1 exhibits a face-centered cubic packing motif, compound 2 displays a supramolecular structure constructed form the 'chains' arranged hexagonally, compound 3 contains [Mo{sub 7.5}W{sub 0.5}O{sub 27}]{sub {infinity}} chain decorated by [Cu(HDABCO)]{sup 2+} cations, which was thenmore » packed into a layer structure. These results show that the same organonitrogen combining with the different POMs will yield different supramolecular networks. -- Graphical abstract: Three new supramolecular compounds based on triethylenediamine and different polyoxometalates have been hydrothermally synthesized and characterized by IR, XPS, TG, elemental analysis and X-ray diffraction analysis.« less

Comparative Genotoxicity and Cytotoxicity of Four Hexavalent Chromium Compounds in Human Bronchial Cells

PubMed Central

Wise, Sandra S.; Holmes, Amie L.; Qin, Qin; Xie, Hong; Katsifis, Spiros P.; Thompson, W. Douglas; Wise, John Pierce

2010-01-01

Hexavalent chromium (Cr(VI)) compounds are well-established human lung carcinogens. Solubility plays an important role in their carcinogenicity with the particulate Cr(VI) compounds being the most carcinogenic. Epidemiology and animal studies suggest that zinc chromate is the most potent particulate Cr(VI) compound, however, there are few comparative data to support these observations. The purpose of this study was to compare the genotoxicity of zinc chromate with two other particulate Cr(VI) compounds, barium chromate and lead chromate, and one soluble Cr(VI) compound, sodium chromate. The clastogenic effects of barium chromate and zinc chromate were similar but lead chromate induced significantly less damage. The levels of DNA damage measured by gamma-H2A.X foci formation were similar for the three particulate chromium compounds. Corrected for chromium uptake differences, we found that zinc chromate and barium chromate were the most cytotoxic and lead chromate and sodium chromate were less cytotoxic. Zinc chromate was more clastogenic than all other chromium compounds and lead chromate was the least clastogenic. There was no significant difference between any of the compounds for the induction of DNA double strand breaks. All together, these data suggest that the difference in the carcinogenic potency of zinc chromate over the other chromium compounds is not due solely to a difference in chromium ion uptake and the zinc cation may in fact have an important role in its carcinogenicity. PMID:20000473

Facile Reductive Silylation of UO22+ to Uranium(IV) Chloride.

PubMed

Kiernicki, John J; Zeller, Matthias; Bart, Suzanne C

2017-01-19

General reductive silylation of the UO 2 2+ cation occurs readily in a one-pot, two-step stoichiometric reaction at room temperature to form uranium(IV) siloxides. Addition of two equivalents of an alkylating reagent to UO 2 X 2 (L) 2 (X=Cl, Br, I, OTf; L=triphenylphosphine oxide, 2,2'-bipyridyl) followed by two equivalents of a silyl (pseudo)halide, R 3 Si-X (R=aryl, alkyl, H; X=Cl, Br, I, OTf, SPh), cleanly affords (R 3 SiO) 2 UX 2 (L) 2 in high yields. Support is included for the key step in the process, reduction of U VI to U V . This procedure is applicable to a wide range of commercially available uranyl salts, silyl halides, and alkylating reagents. Under this protocol, one equivalent of SiCl 4 or two equivalents of Me 2 SiCl 2 results in direct conversion of the uranyl to uranium(IV) tetrachloride. Full spectroscopic and structural characterization of the siloxide products is reported. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

28 CFR 54.605 - Enforcement procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Enforcement procedures. 54.605 Section 54.605 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) NONDISCRIMINATION ON THE BASIS OF SEX IN... procedures. The investigative, compliance, and enforcement procedural provisions of Title VI of the Civil...

28 CFR 54.605 - Enforcement procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Enforcement procedures. 54.605 Section 54.605 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) NONDISCRIMINATION ON THE BASIS OF SEX IN... procedures. The investigative, compliance, and enforcement procedural provisions of Title VI of the Civil...

28 CFR 54.605 - Enforcement procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Enforcement procedures. 54.605 Section 54.605 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) NONDISCRIMINATION ON THE BASIS OF SEX IN... procedures. The investigative, compliance, and enforcement procedural provisions of Title VI of the Civil...

28 CFR 54.605 - Enforcement procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Enforcement procedures. 54.605 Section 54.605 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) NONDISCRIMINATION ON THE BASIS OF SEX IN... procedures. The investigative, compliance, and enforcement procedural provisions of Title VI of the Civil...

28 CFR 54.605 - Enforcement procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Enforcement procedures. 54.605 Section 54.605 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) NONDISCRIMINATION ON THE BASIS OF SEX IN... procedures. The investigative, compliance, and enforcement procedural provisions of Title VI of the Civil...

17 CFR 39.5 - Review of swaps for Commission determination on clearing requirement.

Code of Federal Regulations, 2012 CFR

2012-04-01

... publicly; (vi) Risk management procedures, including measurement and monitoring of credit exposures, initial and variation margin methodology, methodologies for stress testing and back testing, settlement procedures, and default management procedures; (vii) Applicable rules, manuals, policies, or procedures...

Rapid Two-Step Procedure for Large-Scale Purification of Pediocin-Like Bacteriocins and Other Cationic Antimicrobial Peptides from Complex Culture Medium

PubMed Central

Uteng, Marianne; Hauge, Håvard Hildeng; Brondz, Ilia; Nissen-Meyer, Jon; Fimland, Gunnar

2002-01-01

A rapid and simple two-step procedure suitable for both small- and large-scale purification of pediocin-like bacteriocins and other cationic peptides has been developed. In the first step, the bacterial culture was applied directly on a cation-exchange column (1-ml cation exchanger per 100-ml cell culture). Bacteria and anionic compounds passed through the column, and cationic bacteriocins were subsequently eluted with 1 M NaCl. In the second step, the bacteriocin fraction was applied on a low-pressure, reverse-phase column and the bacteriocins were detected as major optical density peaks upon elution with propanol. More than 80% of the activity that was initially in the culture supernatant was recovered in both purification steps, and the final bacteriocin preparation was more than 90% pure as judged by analytical reverse-phase chromatography and capillary electrophoresis. PMID:11823243

Transcatheter valve-in-valve therapy using 6 different devices in 4 anatomic positions: Clinical outcomes and technical considerations.

PubMed

Conradi, Lenard; Silaschi, Miriam; Seiffert, Moritz; Lubos, Edith; Blankenberg, Stefan; Reichenspurner, Hermann; Schaefer, Ulrich; Treede, Hendrik

2015-12-01

Transcatheter valve-in-valve implantation (ViV) is emerging as a novel treatment option for patients with deteriorated bioprostheses. We report our cumulative experience using 6 types of transcatheter heart valves (THVs) in all anatomic positions. Seventy-five consecutive patients (74.1 ± 12.9 years, 50.7% male (38/75), logEuroSCORE I 26.2% ± 17.8%, STS-PROM 8.8% ± 7.4%) receiving ViV procedures from 2008 to 2014 were included for analysis. Data were prospectively gathered and retrospectively analyzed. ViV was performed in aortic (72.0%, 54/75), mitral (22.7%, 17/75), tricuspid (2.7%, 2/75), and pulmonary (2.7%, 2/75) positions. THVs used were Edwards SAPIEN (XT)/SAPIEN3 (52.0%, 39/75), Medtronic Core Valve/Core Valve Evolut(R) (34.7%, 26/75), St Jude Portico (4.0%, 3/75), Boston Scientific Lotus (4.0%, 3/75), Jena Valve (2.7%, 2/75), and Medtronic Engager (2.7%, 2/75). Interval from index procedure to ViV was 9.3 ± 4.9 years. Access was transapical in 53.3% (40/75), transfemoral (transarterial or transvenous) in 42.7% (32/75), transaortic in 2.7% (2/75), and transjugular in 1.3% (1/75). ViV was successful in 97.3% (73/75) with 2 patients requiring sequential THV implantation for initial malpositioning. Overall immediate procedural (≤72 hours) and all-cause 30-day mortality were 2.7% (2/75) and 8.0% (6/75). Corresponding values after aortic ViV were 1.9% (1/54) and 5.6% (3/54). No periprocedural strokes or cases of coronary obstruction occurred. Paravalvular leakage was less than or equal to mild in all cases. After aortic ViV, gradients were max/mean 34.1 ± 14.2/20.1 ± 7.1 mm Hg and effective orifice area (EOA) was 1.5 ± 1.4 cm(2). Corresponding values after mitral ViV were gradients max/mean 14.2 ± 8.2/4.7 ± 3.1 mm Hg and EOA 2.4 ± 0.9 cm(2). ViV can be performed in all anatomic positions with acceptable hemodynamic and clinical outcome in high-risk patients. Increasing importance of ViV can be anticipated considering growing use of surgical bioprostheses. Copyright © 2015 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

34 CFR 104.61 - Procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... of the Offices of the Department of Education OFFICE FOR CIVIL RIGHTS, DEPARTMENT OF EDUCATION NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE Procedures § 104.61 Procedures. The procedural provisions applicable to title VI of the Civil Rights Act of...

34 CFR 104.61 - Procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... of the Offices of the Department of Education OFFICE FOR CIVIL RIGHTS, DEPARTMENT OF EDUCATION NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE Procedures § 104.61 Procedures. The procedural provisions applicable to title VI of the Civil Rights Act of...

34 CFR 104.61 - Procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... of the Offices of the Department of Education OFFICE FOR CIVIL RIGHTS, DEPARTMENT OF EDUCATION NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE Procedures § 104.61 Procedures. The procedural provisions applicable to title VI of the Civil Rights Act of...

34 CFR 104.61 - Procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... of the Offices of the Department of Education OFFICE FOR CIVIL RIGHTS, DEPARTMENT OF EDUCATION NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE Procedures § 104.61 Procedures. The procedural provisions applicable to title VI of the Civil Rights Act of...

34 CFR 104.61 - Procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... of the Offices of the Department of Education OFFICE FOR CIVIL RIGHTS, DEPARTMENT OF EDUCATION NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR ACTIVITIES RECEIVING FEDERAL FINANCIAL ASSISTANCE Procedures § 104.61 Procedures. The procedural provisions applicable to title VI of the Civil Rights Act of...

Electrochemical photovoltaic cell having ternary alloy film

DOEpatents

Russak, Michael A.

1984-01-01

A thin film compound semiconductor electrode comprising CdSe.sub.1-x Te.sub.x (0.ltoreq.x.ltoreq.1) is deposited on a transparent conductive substrate. An electrolyte contacts the film to form a photoactive site. The semiconductor material has a narrow energy bandgap permitting high efficiency for light conversion. The film may be fabricated by: (1) co-evaporation of two II-VI group compounds with a common cation, or (2) evaporation of three elements, concurrenty.

Zn(1-x)MnxTe diluted magnetic semiconductor nanowires grown by molecular beam epitaxy.

PubMed

Zaleszczyk, Wojciech; Janik, Elzbieta; Presz, Adam; Dłuzewski, Piotr; Kret, Sławomir; Szuszkiewicz, Wojciech; Morhange, Jean-François; Dynowska, Elzbieta; Kirmse, Holm; Neumann, Wolfgang; Petroutchik, Aleksy; Baczewski, Lech T; Karczewski, Grzegorz; Wojtowicz, Tomasz

2008-11-01

It is shown that the growth of II-VI diluted magnetic semiconductor nanowires is possible by the catalytically enhanced molecular beam epitaxy (MBE). Zn(1-x)MnxTe NWs with manganese content up to x=0.60 were produced by this method. X-ray diffraction, Raman spectroscopy, and temperature dependent photoluminescence measurements confirm the incorporation of Mn(2+) ions in the cation substitutional sites of the ZnTe matrix of the NWs.

Amazon kaolinite functionalized with diethylenetriamine moieties for U(VI) removal: thermodynamic of cation-basic interactions.

PubMed

Guerra, Denis L; Leidens, Victor L; Viana, Rúbia R; Airoldi, Claudio

2010-08-15

The compound N-[3-(trimethoxysilyl)propyl]diethylenetriamine (MPDET) was anchored onto Amazon kaolinite surface (KLT) by heterogeneous route. The modified and natural kaolinite clay samples were characterized by transmission electron microscopy (TEM), scanning electron microscopic (SEM), N(2) adsorption, powder X-ray diffraction, thermal analysis, ion exchange capacities, and nuclear magnetic nuclei of (29)Si and (13)C. The well-defined peaks obtained in the (13)C NMR spectrum in the 5.0-62.1 ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The adsorption of uranyl on natural (KLT) and modified (KLT(MPDET)) kaolinite clays was investigated as a function of the solution pH, metal concentration, temperature, and ionic strength. The ability of these materials to remove U(VI) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 8.37 x 10(-3) and 13.87 x 10(-3) mmol g(-1) for KLT and KLT(MPDET) at 298 K, respectively. The energetic effects (Delta(int)H, Delta(int)G, and Delta(int)S) caused by metal cations adsorption were determined through calorimetric titrations. Copyright 2010. Published by Elsevier B.V.

14 CFR 431.37 - Mission readiness.

Code of Federal Regulations, 2014 CFR

2014-01-01

... contingency abort plans and procedures, if any, as required under § 431.39; (vi) Unresolved safety issues.... (2) Procedures that ensure mission constraints, rules, contingency abort and emergency abort...

14 CFR 431.37 - Mission readiness.

Code of Federal Regulations, 2012 CFR

2012-01-01

... contingency abort plans and procedures, if any, as required under § 431.39; (vi) Unresolved safety issues.... (2) Procedures that ensure mission constraints, rules, contingency abort and emergency abort...

14 CFR 431.37 - Mission readiness.

Code of Federal Regulations, 2013 CFR

2013-01-01

... contingency abort plans and procedures, if any, as required under § 431.39; (vi) Unresolved safety issues.... (2) Procedures that ensure mission constraints, rules, contingency abort and emergency abort...

14 CFR 431.37 - Mission readiness.

Code of Federal Regulations, 2011 CFR

2011-01-01

... contingency abort plans and procedures, if any, as required under § 431.39; (vi) Unresolved safety issues.... (2) Procedures that ensure mission constraints, rules, contingency abort and emergency abort...

14 CFR 431.37 - Mission readiness.

Code of Federal Regulations, 2010 CFR

2010-01-01

... contingency abort plans and procedures, if any, as required under § 431.39; (vi) Unresolved safety issues.... (2) Procedures that ensure mission constraints, rules, contingency abort and emergency abort...

28 CFR 902.5 - Hearing procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Hearing procedures. 902.5 Section 902.5 Judicial Administration NATIONAL CRIME PREVENTION AND PRIVACY COMPACT COUNCIL DISPUTE ADJUDICATION PROCEDURES § 902.5 Hearing procedures. (a) The hearing shall be open to the public pursuant to Article VI (d...

Comparison of three sampling and analytical methods for the determination of airborne hexavalent chromium.

PubMed

Boiano, J M; Wallace, M E; Sieber, W K; Groff, J H; Wang, J; Ashley, K

2000-08-01

A field study was conducted with the goal of comparing the performance of three recently developed or modified sampling and analytical methods for the determination of airborne hexavalent chromium (Cr(VI)). The study was carried out in a hard chrome electroplating facility and in a jet engine manufacturing facility where airborne Cr(VI) was expected to be present. The analytical methods evaluated included two laboratory-based procedures (OSHA Method ID-215 and NIOSH Method 7605) and a field-portable method (NIOSH Method 7703). These three methods employ an identical sampling methodology: collection of Cr(VI)-containing aerosol on a polyvinyl chloride (PVC) filter housed in a sampling cassette, which is connected to a personal sampling pump calibrated at an appropriate flow rate. The basis of the analytical methods for all three methods involves extraction of the PVC filter in alkaline buffer solution, chemical isolation of the Cr(VI) ion, complexation of the Cr(VI) ion with 1,5-diphenylcarbazide, and spectrometric measurement of the violet chromium diphenylcarbazone complex at 540 nm. However, there are notable specific differences within the sample preparation procedures used in three methods. To assess the comparability of the three measurement protocols, a total of 20 side-by-side air samples were collected, equally divided between a chromic acid electroplating operation and a spray paint operation where water soluble forms of Cr(VI) were used. A range of Cr(VI) concentrations from 0.6 to 960 microg m(-3), with Cr(VI) mass loadings ranging from 0.4 to 32 microg, was measured at the two operations. The equivalence of the means of the log-transformed Cr(VI) concentrations obtained from the different analytical methods was compared. Based on analysis of variance (ANOVA) results, no statistically significant differences were observed between mean values measured using each of the three methods. Small but statistically significant differences were observed between results obtained from performance evaluation samples for the NIOSH field method and the OSHA laboratory method.

U(VI) uranyl cation-cation interactions in framework germanates.

PubMed

Morrison, Jessica M; Moore-Shay, Laura J; Burns, Peter C

2011-03-21

The isomorphous compounds NH(4)[(UO(6))(2)(UO(2))(9)(GeO(4))(GeO(3)(OH))] (1), K[(UO(6))(2)(UO(2))(9)(GeO(4))(GeO(3)(OH))] (2), Li(3)O[(UO(6))(2)(UO(2))(9)(GeO(4))(GeO(3)(OH))] (3), and Ba[(UO(6))(2)(UO(2))(9)(GeO(4))(2)] (4) were synthesized by hydrothermal reaction at 220 °C. The structures were determined using single crystal X-ray diffraction and refined to R(1) = 0.0349 (1), 0.0232 (2), 0.0236 (3), 0.0267 (4). Each are trigonal, P(3)1c. 1: a = 10.2525(5), c = 17.3972(13), V = 1583.69(16) Å(3), Z = 2; 2: a = 10.226(4), c = 17.150(9), V = 1553.1(12) Å(3), Z = 2; 3: a = 10.2668(5), c = 17.0558(11), V = 1556.94(15) Å(3), Z = 2; 4: a = 10.2012(5), c = 17.1570(12), V = 1546.23(15) Å(3), Z = 2. There are three symmetrically independent U sites in each structure, two of which correspond to typical (UO(2))(2+) uranyl ions and the other of which is octahedrally coordinated by six O atoms. One of the uranyl ions donates a cation-cation interaction, and accepts a different cation-cation interaction. The linkages between the U-centered polyhedra result in a relatively dense three-dimensional framework. Ge and low-valence sites are located within cavities in the framework of U-polyhedra. Chemical, thermal, and spectroscopic characterizations are provided.

Potentiometric chemical sensors from lignin-poly(propylene oxide) copolymers doped by carbon nanotubes.

PubMed

Rudnitskaya, Alisa; Evtuguin, Dmitry V; Costa, Luis C; Graça, M Pedro F; Fernandes, António J S; Correia, M Rosario P; Gomes, M Teresa S R; Oliveira, J A B P

2013-01-21

Hardwood and softwood lignins obtained from industrial sulphite and kraft and laboratory oxygen-organosolv pulping processes were employed in co-polymerization with tolylene 2,4-diisocyanate terminated poly(propylene glycol). The obtained lignin-based polyurethanes were doped with 0.72 w/w% of multiwall carbon nanotubes (MWCNTs) with the aim of increasing their electrical conductivity to the levels suitable for sensor applications. Effects of the polymer doping with MWCNTs were assessed using electrical impedance (EIS) and UV-Resonance Raman (UV-RR) spectroscopy. Potentiometric sensors were prepared by drop casting of liquid polymer on the surface of carbon glass or platinum electrodes. Lignin-based sensors displayed a very low or no sensitivity to all alkali, alkali-earth and transition metal cations ions except Cr(VI) at pH 2. Response to Cr(VI) values of 39, 50 and 53 mV pX(-1) for the sensors based on kraft, organosolv and lignosulphonate lignins, respectively, were observed. Redox sensitivity values close to the theoretical values of 20 and 21 mV pX(-1) for organosolv and lignosulphonate based sensors respectively were detected in the Cr(III)/Cr(VI) solutions while a very low response was observed in the solutions containing Fe(CN)(6)(3-/4-). Conducting composite lignin-based polyurethanes doped with MWCNTs were suggested as being promising materials for Cr(VI)-sensitive potentiometric sensors.

Kinetics of Cation and Oxyanion Adsorption and Desorption on Ferrihydrite: Roles of Ferrihydrite Binding Sites and a Unified Model.

PubMed

Tian, Lei; Shi, Zhenqing; Lu, Yang; Dohnalkova, Alice C; Lin, Zhang; Dang, Zhi

2017-09-19

Quantitative understanding the kinetics of toxic ion reactions with various heterogeneous ferrihydrite binding sites is crucial for accurately predicting the dynamic behavior of contaminants in environment. In this study, kinetics of As(V), Cr(VI), Cu(II), and Pb(II) adsorption and desorption on ferrihydrite was studied using a stirred-flow method, which showed that metal adsorption/desorption kinetics was highly dependent on the reaction conditions and varied significantly among four metals. High resolution scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy showed that all four metals were distributed within the ferrihydrite aggregates homogeneously after adsorption reactions. Based on the equilibrium model CD-MUSIC, we developed a novel unified kinetics model applicable for both cation and oxyanion adsorption and desorption on ferrihydrite, which is able to account for the heterogeneity of ferrihydrite binding sites, different binding properties of cations and oxyanions, and variations of solution chemistry. The model described the kinetic results well. We quantitatively elucidated how the equilibrium properties of the cation and oxyanion binding to various ferrihydrite sites and the formation of various surface complexes controlled the adsorption and desorption kinetics at different reaction conditions and time scales. Our study provided a unified modeling method for the kinetics of ion adsorption/desorption on ferrihydrite.

Tuning the Magnetic Properties of Metal Oxide Nanocrystal Heterostructures by Cation Exchange

PubMed Central

2013-01-01

For three types of colloidal magnetic nanocrystals, we demonstrate that postsynthetic cation exchange enables tuning of the nanocrystal’s magnetic properties and achieving characteristics not obtainable by conventional synthetic routes. While the cation exchange procedure, performed in solution phase approach, was restricted so far to chalcogenide based semiconductor nanocrystals, here ferrite-based nanocrystals were subjected to a Fe2+ to Co2+ cation exchange procedure. This allows tracing of the compositional modifications by systematic and detailed magnetic characterization. In homogeneous magnetite nanocrystals and in gold/magnetite core shell nanocrystals the cation exchange increases the coercivity field, the remanence magnetization, as well as the superparamagnetic blocking temperature. For core/shell nanoheterostructures a selective doping of either the shell or predominantly of the core with Co2+ is demonstrated. By applying the cation exchange to FeO/CoFe2O4 core/shell nanocrystals the Neél temperature of the core material is increased and exchange-bias effects are enhanced so that vertical shifts of the hysteresis loops are obtained which are superior to those in any other system. PMID:23362940

State Scan--Residential Placements: Blind/VI and Deaf/HI. Information Research Cadre

ERIC Educational Resources Information Center

Blythe, Teresa

2013-01-01

In this Information Research Cadre, Teresa Blythe responds to the following research question: For those states that have residential schools for the Blind/VI and Deaf/HI students, have they developed policies and procedures for residential placement of these students? To develop this response Blythe conducted web research utilizing numerous…

Virtual Impactors: Search and Destroy

NASA Astrophysics Data System (ADS)

Milani, Andrea; Chesley, Steven R.; Boattini, Andrea; Valsecchi, Giovanni B.

2000-05-01

If for an asteroid which has been observed only over a short arc and then lost there are orbits compatible with the observations resulting in collisions, recovery would be desirable to decide if it will actually impact. If recovery is essentially impractical, as is the case for many small asteroids in the 100- to 500-m-diameter range, the next best thing is to make sure that the lost asteroid is not on a collision course. We propose a method for achieving this guarantee, with an observational effort far smaller than the one required for recovery. The procedure involves the computation of an orbit that is compatible with the available observations and, by hypothesis, results in an impact at some later encounter; this we call a virtual impactor (VI). The collision at some future time is a strong constraint; thus the VI has a well determined orbit. We show that it is possible to compute for each given time of observation the skyprint of the VI, that is the set of astrometric positions compatible with an impact (or a near impact). The skyprint needs to be scanned by powerful enough telescopes to perform a negative observation; once this has been done for the skyprints of all VIs, collisions can be excluded even without recovery. We propose to apply this procedure to the case of the lost asteroid 1998 OX 4, for which we have found orbital solutions with impacts in the years 2014, 2038, 2044, and 2046. Suitable observing windows are found when the VI would be close to the Earth in 2001 and in 2003, and the corresponding skyprints are small enough to be covered with very few frames. This procedure might become more and more necessary in the future, as the number of discoveries of small potentially hazardous asteroids increases; we discuss the general principles and the validation procedures that should apply to such a VI removal campaign.

Remediation of hexavalent chromium contamination in chromite ore processing residue by sodium dithionite and sodium phosphate addition and its mechanism.

PubMed

Li, Yunyi; Cundy, Andrew B; Feng, Jingxuan; Fu, Hang; Wang, Xiaojing; Liu, Yangsheng

2017-05-01

Large amounts of chromite ore processing residue (COPR) wastes have been deposited in many countries worldwide, generating significant contamination issues from the highly mobile and toxic hexavalent chromium species (Cr(VI)). In this study, sodium dithionite (Na 2 S 2 O 4 ) was used to reduce Cr(VI) to Cr(III) in COPR containing high available Fe, and then sodium phosphate (Na 3 PO 4 ) was utilized to further immobilize Cr(III), via a two-step procedure (TSP). Remediation and immobilization processes and mechanisms were systematically investigated using batch experiments, sequential extraction studies, X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). Results showed that Na 2 S 2 O 4 effectively reduced Cr(VI) to Cr(III), catalyzed by Fe(III). The subsequent addition of Na 3 PO 4 further immobilized Cr(III) by the formation of crystalline CrPO 4 ·6H 2 O. However, addition of Na 3 PO 4 simultaneously with Na 2 S 2 O 4 (via a one-step procedure, OSP) impeded Cr(VI) reduction due to the competitive reaction of Na 3 PO 4 and Na 2 S 2 O 4 with Fe(III). Thus, the remediation efficiency of the TSP was much higher than the corresponding OSP. Using an optimal dosage in the two-step procedure (Na 2 S 2 O 4 at a dosage of 12× the stoichiometric requirement for 15 days, and then Na 3 PO 4 in a molar ratio (i.e. Na 3 PO 4 : initial Cr(VI)) of 4:1 for another 15 days), the total dissolved Cr in the leachate determined via Toxicity Characteristic Leaching Procedure (TCLP Cr) testing of our samples was reduced to 3.8 mg/L (from an initial TCLP Cr of 112.2 mg/L, i.e. at >96% efficiency). Copyright © 2017 Elsevier Ltd. All rights reserved.

Ring test evaluation of the detection of influenza A virus in swine oral fluids by real-time reverse-transcription polymerase chain reaction and virus isolation

PubMed Central

Goodell, Christa K.; Zhang, Jianqiang; Strait, Erin; Harmon, Karen; Patnayak, Devi; Otterson, Tracy; Culhane, Marie; Christopher-Hennings, Jane; Clement, Travis; Leslie-Steen, Pamela; Hesse, Richard; Anderson, Joe; Skarbek, Kevin; Vincent, Amy; Kitikoon, Pravina; Swenson, Sabrina; Jenkins-Moore, Melinda; McGill, Jodi; Rauh, Rolf; Nelson, William; O’Connell, Catherine; Shah, Rohan; Wang, Chong; Main, Rodger; Zimmerman, Jeffrey J.

2016-01-01

The probability of detecting influenza A virus (IAV) in oral fluid (OF) specimens was calculated for each of 13 assays based on real-time reverse-transcription polymerase chain reaction (rRT-PCR) and 7 assays based on virus isolation (VI). The OF specimens were inoculated with H1N1 or H3N2 IAV and serially diluted 10-fold (10−1 to 10−8). Eight participating laboratories received 180 randomized OF samples (10 replicates × 8 dilutions × 2 IAV subtypes plus 20 IAV-negative samples) and performed the rRT-PCR and VI procedure(s) of their choice. Analysis of the results with a mixed-effect logistic-regression model identified dilution and assay as variables significant (P < 0.0001) for IAV detection in OF by rRT-PCR or VI. Virus subtype was not significant for IAV detection by either rRT-PCR (P = 0.457) or VI (P = 0.101). For rRT-PCR the cycle threshold (Ct) values increased consistently with dilution but varied widely. Therefore, it was not possible to predict VI success on the basis of Ct values. The success of VI was inversely related to the dilution of the sample; the assay was generally unsuccessful at lower virus concentrations. Successful swine health monitoring and disease surveillance require assays with consistent performance, but significant differences in reproducibility were observed among the assays evaluated. PMID:26733728

14 CFR 121.422 - Aircraft dispatchers: Initial and transition ground training.

Code of Federal Regulations, 2011 CFR

2011-01-01

... computations; (iv) Basic airplane performance dispatch requirements and procedures; (v) Flight planning including track selection, flight time analysis, and fuel requirements; and (vi) Emergency procedures. (3... procedures, and other subjects having a bearing on dispatcher duties and responsibilities; (ii) Flight...

14 CFR 121.422 - Aircraft dispatchers: Initial and transition ground training.

Code of Federal Regulations, 2012 CFR

2012-01-01

... computations; (iv) Basic airplane performance dispatch requirements and procedures; (v) Flight planning including track selection, flight time analysis, and fuel requirements; and (vi) Emergency procedures. (3... procedures, and other subjects having a bearing on dispatcher duties and responsibilities; (ii) Flight...

14 CFR 121.422 - Aircraft dispatchers: Initial and transition ground training.

Code of Federal Regulations, 2013 CFR

2013-01-01

... computations; (iv) Basic airplane performance dispatch requirements and procedures; (v) Flight planning including track selection, flight time analysis, and fuel requirements; and (vi) Emergency procedures. (3... procedures, and other subjects having a bearing on dispatcher duties and responsibilities; (ii) Flight...

14 CFR 121.422 - Aircraft dispatchers: Initial and transition ground training.

Code of Federal Regulations, 2010 CFR

2010-01-01

... computations; (iv) Basic airplane performance dispatch requirements and procedures; (v) Flight planning including track selection, flight time analysis, and fuel requirements; and (vi) Emergency procedures. (3... procedures, and other subjects having a bearing on dispatcher duties and responsibilities; (ii) Flight...

14 CFR 121.422 - Aircraft dispatchers: Initial and transition ground training.

Code of Federal Regulations, 2014 CFR

2014-01-01

... computations; (iv) Basic airplane performance dispatch requirements and procedures; (v) Flight planning including track selection, flight time analysis, and fuel requirements; and (vi) Emergency procedures. (3... procedures, and other subjects having a bearing on dispatcher duties and responsibilities; (ii) Flight...

Balancing Materiel Readiness Risks and Concurrency in Weapon System Acquisition: A Handbook for Program Managers

DTIC Science & Technology

1984-07-15

ftViCCii UWNC COMMAND MIX CM AFT DCP OUTUNC moo ffEOUCST FOR PROGRAM DECISION DRAFT DCP AFSC REVIEW RECOWMEM CATIONS OHI*OC Arse wioc...CS.P3 F16. El*. P» MCA Exhibit 4-6b. EMBEDDED COMPUTER HARDWARE vs. SOFTWARE Exhibit 4-6c. DoD EMBEDDED COMPUTER MARKET 31.J1...the mix of stores carried by that vehicle 6. Anticipated combat tactics employed by the carrying or launching vehicle and its maneuvering

A new oxomolybdate component extracted from the "virtual dynamic library" yielding the macrocyclic anion [(Mo(VI)(8)O(28))(4)(Mo(V)(2)O(2)S(2))(4)](24-).

PubMed

Korenev, Vladimir S; Boulay, Antoine G; Dolbecq, Anne; Sokolov, Maxim N; Hijazi, Akram; Floquet, Sébastien; Fedin, Vladimir P; Cadot, Emmanuel

2010-11-01

A rare isomer of the {Mo(8)O(28)}(8-) anion has been trapped from an acidified aqueous solution of molybdate by using the {Mo(2)O(2)S(2)}(2+) oxothio cation as the linker and isolated as a part of a unique macrocyclic anion, which consists of four isopolyoxomolybdate fragments {Mo(8)O(28)} bridged by four {Mo(2)O(2)S(2)} units.

Sorption of uranyl ions from various acido systems by amphoteric epoxy amine ion-exchange resins

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

Rychkov, V.N.; Radionov, B.K.; Molochnikov, L.S.

1995-03-01

Sorption of uranyl ions by epoxy amine ampholytes with N-monomethylenephosphonic acid groups modified with pyridine or quaternary ammonium groups was studied under dynamic conditions. Heterocyclic nitrogen favors sorption of uranyl ion from fluoride, sulfate, and fluoride-sulfate solutions. The ESR studies of mono- and bimetallic forms of nitrogen-containing ampholytes with copper(II) as paramagnetic marker revealed the characteristics of uranium(VI) interaction with cation- and anion-exchange groups and its dependence on the fluoride content in solution.

Elucidating bonding preferences in tetrakis(imido)uranate(VI) dianions

NASA Astrophysics Data System (ADS)

Anderson, Nickolas H.; Xie, Jing; Ray, Debmalya; Zeller, Matthias; Gagliardi, Laura; Bart, Suzanne C.

2017-09-01

Actinyl species, [AnO2]2+, are well-known derivatives of the f-block because of their natural occurrence and essential roles in the nuclear fuel cycle. Along with their nitrogen analogues, [An(NR)2]2+, actinyls are characterized by their two strong trans-An-element multiple bonds, a consequence of the inverse trans influence. We report that these robust bonds can be weakened significantly by increasing the number of multiple bonds to uranium, as demonstrated by a family of uranium(VI) dianions bearing four U-N multiple bonds, [M]2[U(NR)4] (M = Li, Na, K, Rb, Cs). Their geometry is dictated by cation coordination and sterics rather than by electronic factors. Multiple bond weakening by the addition of strong π donors has the potential for applications in the processing of high-valent actinyls, commonly found in environmental pollutants and spent nuclear fuels.

Use of spectroscopic technique to develop a reagent for Mo(VI) utilizing micellar effects on complex formation

NASA Astrophysics Data System (ADS)

Taşcioğlu, Sülin; Kaki, E.; Taşcioğlu, Senay

2012-09-01

Ultraviolet and visible spectral properties of aqueous solutions of molybdenum(VI) (Mo), gallic acid (GA), Lalanine (Ala), and L-Phenylalanine (Phe), and of their binary and ternary solutions were investigated in the absence and presence of anionic, cationic, and nonionic surfactant micelles. Evaluation of the spectra in a comparative way revealed that both Ala and Phe form ternary complexes with Mo and GA. The formation of a quaternary complex between Mo, GA, Phe, and cetyltrimethylammonium bromide at pH 4.5 provided a reagent system with a strikingly high sensitivity (1.2•106 l/(mol•cm)) for use in the spectrophotometric determination of Mo. A mechanism of micellar effects was discussed in terms of the substrate molecular charge and hydrophobicity, and rationalized on the basis of the spectral data obtained above and below the isoelectric pH of the amino acids.

Synthesis and structural features of U VI and V IV chelate complexes with (hhmmbH)Cl·H 2O [hhmmb = {3-hydroxyl-5-(hydroxymethyl)-2-methylpyridine-4-yl-methylene}benzohydrazide], a new Schiff base ligand derived from vitamin B6

NASA Astrophysics Data System (ADS)

Back, Davi Fernando; Ballin, Marco Aurélio; de Oliveira, Gelson Manzoni

2009-10-01

The Schiff base ligand {3-hydroxyl-5-(hydroxymethyl)-2-methylpyridine-4-yl-methylene}benzohydrazide hydrochloride monohydrated {(hhmmbH)Cl·H 2O} ( 1) was prepared by reaction of pyridoxine hydrochloride with benzoic acid hydrazide. The reaction of 1 with [VO(acac) 2] and triethylamine yields the neutral vanadium IV complex [VO 2(hhmmb)]·Py ( 2), with a distorted quadratic pyramidal configuration. The Schiff base 1 reacts also with UO 2(NO 3) 2·6H 2O and triethylamine under deprotonation giving the uranium VI cationic complexes [UO 2(hhmmb)(H 2O)Cl] + ( 3) and [UO 2(hhmmb)(CH 3OH)Cl] + ( 4), both showing the classical pentagonal bipyrimidal geometry of UO22+ complexes. The structural features of all compounds are discussed.

Synthesis and X-ray Crystallography of [Mg(H2O)6][AnO2(C2H5COO)3]2 (An = U, Np, or Pu).

PubMed

Serezhkin, Viktor N; Grigoriev, Mikhail S; Abdulmyanov, Aleksey R; Fedoseev, Aleksandr M; Savchenkov, Anton V; Serezhkina, Larisa B

2016-08-01

Synthesis and X-ray crystallography of single crystals of [Mg(H2O)6][AnO2(C2H5COO)3]2, where An = U (I), Np (II), or Pu (III), are reported. Compounds I-III are isostructural and crystallize in the trigonal crystal system. The structures of I-III are built of hydrated magnesium cations [Mg(H2O)6](2+) and mononuclear [AnO2(C2H5COO)3](-) complexes, which belong to the AB(01)3 crystallochemical group of uranyl complexes (A = AnO2(2+), B(01) = C2H5COO(-)). Peculiarities of intermolecular interactions in the structures of [Mg(H2O)6][UO2(L)3]2 complexes depending on the carboxylate ion L (acetate, propionate, or n-butyrate) are investigated using the method of molecular Voronoi-Dirichlet polyhedra. Actinide contraction in the series of U(VI)-Np(VI)-Pu(VI) in compounds I-III is reflected in a decrease in the mean An═O bond lengths and in the volume and sphericity degree of Voronoi-Dirichlet polyhedra of An atoms.

30 CFR 250.917 - What are the CVA's primary duties during the fabrication phase?

Code of Federal Regulations, 2010 CFR

2010-07-01

... adherence to such procedures; (v) Welder and welding procedure qualification and identification; (vi... requirements, and evaluation results of the specified examinations; (viii) Destructive testing requirements and...

Interplay between Surface Chemistry, Precursor Reactivity, and Temperature Determines Outcome of ZnS Shelling Reactions on CuInS2 Nanocrystals

PubMed Central

2018-01-01

ZnS shelling of I–III–VI2 nanocrystals (NCs) invariably leads to blue-shifts in both the absorption and photoluminescence spectra. These observations imply that the outcome of ZnS shelling reactions on I–III–VI2 colloidal NCs results from a complex interplay between several processes taking place in solution, at the surface of, and within the seed NC. However, a fundamental understanding of the factors determining the balance between these different processes is still lacking. In this work, we address this need by investigating the impact of precursor reactivity, reaction temperature, and surface chemistry (due to the washing procedure) on the outcome of ZnS shelling reactions on CuInS2 NCs using a seeded growth approach. We demonstrate that low reaction temperatures (150 °C) favor etching, cation exchange, and alloying regardless of the precursors used. Heteroepitaxial shell overgrowth becomes the dominant process only if reactive S- and Zn-precursors (S-ODE/OLAM and ZnI2) and high reaction temperatures (210 °C) are used, although a certain degree of heterointerfacial alloying still occurs. Remarkably, the presence of residual acetate at the surface of CIS seed NCs washed with ethanol is shown to facilitate heteroepitaxial shell overgrowth, yielding for the first time CIS/ZnS core/shell NCs displaying red-shifted absorption spectra, in agreement with the spectral shifts expected for a type-I band alignment. The insights provided by this work pave the way toward the design of improved synthesis strategies to CIS/ZnS core/shell and alloy NCs with tailored elemental distribution profiles, allowing precise tuning of the optoelectronic properties of the resulting materials. PMID:29657360

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.

Vertical muscle transposition with silicone band belting in VI nerve palsy

PubMed Central

Freitas, Cristina

2016-01-01

A woman aged 60 years developed a Millard-Gubler syndrome after a diagnosis of a cavernous angioma in the median and paramedian areas of the pons. In this context, she presented a right VI nerve palsy, right conjugate gaze palsy, facial palsy and left hemiparesis. To improve the complete VI nerve palsy, we planned a modified transposition approach, in which procedure we made a partial transposition of vertical rectus with a silicone band that was fixated posteriorly. After the procedure, the patient gained the ability to slightly abduct the right eye. We found no compensatory torticollis in the primary position of gaze. There was also an improvement of elevation and depression movements of the right eye. We obtained satisfactory results with a theoretically reversible technique, which is adjustable intraoperatively with no need of muscle detachment, preventing anterior segment ischaemia and allowing simultaneous recession of the medial rectus muscles, if necessary. PMID:27974341

Combinations of Response-Dependent and Response-Independent Schedule-Correlated Stimulus Presentation in an Observing Procedure

ERIC Educational Resources Information Center

DeFulio, Anthony; Hackenberg, Timothy D.

2008-01-01

Pigeons pecked a response key on a variable-interval (VI) schedule, in which responses produced food every 40 s, on average. These VI periods, or components, alternated in irregular fashion with extinction components in which food was unavailable. Pecks on a second (observing) key briefly produced exteroceptive stimuli (houselight flashes)…

Chemical processes for the extreme enrichment of tellurium into marine ferromanganese oxides

NASA Astrophysics Data System (ADS)

Kashiwabara, Teruhiko; Oishi, Yasuko; Sakaguchi, Aya; Sugiyama, Toshiki; Usui, Akira; Takahashi, Yoshio

2014-04-01

Tellurium, an element of growing economic importance, is extremely enriched in marine ferromanganese oxides. We investigated the mechanism of this enrichment using a combination of spectroscopic analysis and adsorption/coprecipitation experiments. X-ray Absorption Near-Edge Structure (XANES) analysis showed that in adsorption/coprecipitation systems, Te(IV) was oxidized on δ-MnO2 and not oxidized on ferrihydrite. Extended X-ray Absorption Fine Structure (EXAFS) analysis showed that both Te(IV) and Te(VI) were adsorbed on the surface of δ-MnO2 and ferrihydrite via formation of inner-sphere complexes. In addition, Te(VI) can be structurally incorporated into the linkage of Fe octahedra through a coprecipitation process because of its molecular geometry that is similar to the Fe octahedron. The largest distribution coefficient obtained in the adsorption/coprecipitation experiments was for the Te(VI)/ferrihydrite coprecipitation system, and it was comparable to those calculated from the distribution between natural ferromanganese oxides and seawater. Our XAFS and micro-focused X-ray fluorescence (μ-XRF) mapping of natural ferromanganese oxides showed that Te was structurally incorporated as Te(VI) in Fe (oxyhydr)oxide phases. We conclude that the main process for the enrichment of Te in ferromanganese oxides is structural incorporation of Te(VI) into Fe (oxyhydr)oxide phases through coprecipitation. This mechanism can explain the unique degree of enrichment of Te compared with other oxyanions, which are mainly enriched via adsorption on the surface of the solid structures. In particular, the great contrast in the distributions of Te and Se is caused by their oxidized species: (i) the similar geometry of the Te(VI) molecule to Fe octahedron, and (ii) quite soluble nature of Se(VI). Coexisting Mn oxide phases may promote structural incorporation of Te(VI) by oxidation of Te(IV), although the surface oxidation itself may not work as the critical enrichment process as in the case of some cations. This enrichment mechanism also means that ferromanganese oxides mainly scavenge dominant Te(VI) species from seawater and do not affect its species distribution in seawater, as described in a previous model. The variation in Te abundances and the correlation of Te concentration with the growth rate of natural ferromanganese oxides are consistent with the coprecipitation mechanism.

Phase stability of Keplerate-type polyoxomolybdates controlled by added cationic surfactant.

PubMed

Fan, Dawei; Hao, Jingcheng

2009-05-15

Phase stability of two nanometer-scale Keplerate-type polyoxomolybdates, (NH(4))(42)[Mo(VI)(72)Mo(V)(60)O(372)(CH(3)COO)(30)(H(2)O)(72)]300H(2)O10CH(3)COONH(4) ({Mo(132)}) and Mo(VI)(72)Fe(III)(30)O(252)L(102)ca. 180H(2)O with L=H(2)O/CH(3)COO(-)/Mo(2)O(n-)(8/9) ({Mo(72)Fe(30)}), can be easily achieved by controlling the concentration of a cationic surfactant, tetradecyltrimethylammonium bromide (TTABr), in aqueous solution. Precipitates and floccules were observed when the stoichiometric ratios of rTTA+/{Mo132} and rTTA+/{Mo72Fe30} were 40:1 and 90:1, respectively, which were determined by zeta potential measurements. The surface charge properties and structure morphologies of {Mo(132)} and {Mo(72)Fe(30)} induced by controlling cationic TTABr in aqueous solution were determined by zeta potential measurements and transmission electron microscopy (TEM) observations. {Mo(132)} and {Mo(72)Fe(30)} can self-assemble into supramolecular "Blackberry" structures and exist at compositions less than the stoichiometric ratios of rTTA+/{Mo132} and rTTA+/{Mo72Fe30} in aqueous solution. Above the 1:1 stoichiometric ratio of TTABr/{Mo(132)} or TTABr/{Mo(72)Fe(30)}, the precipitates and floccules dissolve. Dynamic laser light scattering (DLS) measurements clearly demonstrated that the R(h) values have essentially no angular dependence at excess amounts of TTABr, suggesting the presence of spherically symmetric aggregates of {Mo(132)} and {Mo(72)Fe(30)}. Bilayer-like structures in aqueous solution were also demonstrated by TEM images. The interesting phase transition observed in our model systems of {Mo(132)} and {Mo(72)Fe(30)} macroanions with high chemical stability, similar shape, and masses could provide models for the understanding of more complex polyelectrolyte solutions and self-assembled soft magnetic materials and in bioapplications for highly selective adsorbents of proteins with different molecular sizes and charges.

Structural distortions in monolayers of binary semiconductors

NASA Astrophysics Data System (ADS)

Kumari, Poonam; Debnath, Saikat; Mahadevan, Priya

2018-01-01

We examine the structural properties of free-standing II-VI and III-V semiconductors at the monolayer limit within first principle density functional theory calculations. A nonpolar buckled structure was found to be favored over a polar buckled structure. While an obvious reason for this may be traced to the contribution from dipole-dipole interactions present in the polar structure which would destabilize it with respect to the nonpolar structure, Coulomb interactions between electrons on the cations and anions are found to be the reason for the nonpolar structure to be favoured. A route to tune the Coulomb interaction between the electrons on the cations and anions is through biaxial tensile strain. This allows for a planar graphitic phase in CdS to be stabilized at just 2% tensile strain. Strain also shifts the valence band maximum from the Γ point to the K point, opening up opportunities for exploring spin-valley physics in these materials.

Prediction of Giant Thermoelectric Efficiency in Crystals with Interlaced Nanostructure.

PubMed

Puzyrev, Y S; Shen, X; Pantelides, S T

2016-01-13

We present a theoretical study of the thermoelectric efficiency of "interlaced crystals", recently discovered in hexagonal-CuInS2 nanoparticles. Interlaced crystals are I-III-VI2 or II-IV-V2 tetrahedrally bonded compounds. They have a perfect Bravais lattice in which the two cations have an infinite set of possible ordering patterns within the cation sublattice. The material comprises nanoscale interlaced domains and phases with corresponding boundaries. Here we employ density functional theory and large-scale molecular dynamics calculations based on model classical potentials to demonstrate that the phase and domain boundaries are effective phonon scatterers and greatly suppress thermal conductivity. However, the absence of both structural defects and strain in the interlaced material results in a minimal effect on electronic properties. We predict an increase of thermal resistivity of up to 2 orders of magnitude, which makes interlaced crystals an exceptional candidate for thermoelectric applications.

Immobilization of hexavalent chromium in contaminated soils using biochar supported nanoscale iron sulfide composite.

PubMed

Lyu, Honghong; Zhao, Hang; Tang, Jingchun; Gong, Yanyan; Huang, Yao; Wu, Qihang; Gao, Bin

2018-03-01

Biochar supported carboxymethyl cellulose (CMC)-stabilized nanoscale iron sulfide (FeS) composite (CMC-FeS@biochar) was prepared and tested for immobilization of hexavalent chromium Cr(VI) in soil. Results of UV-vis and transmission electron microscopy (TEM) showed that the backbone of biochar suppressed the aggregation of FeS, resulting in smaller particle size and more sorption sites than bare FeS. The composite at a dosage of 2.5 mg per gram soil displayed an enhanced Cr(VI) immobilization efficiency (a 94.7% reduction in the toxicity characteristic leaching procedure (TCLP) based leachability and a 95.6% reduction in the CaCl 2 extraction) compared to plain biochar and bare FeS. Sequential extraction procedure (SEP) and X-ray photoelectron spectroscopy (XPS) analysis suggested that CMC-FeS@biochar promoted the conversion of more accessible Cr (exchangeable and carbonate-bound fractions) into the less accessible forms (iron-manganese oxides-bound, organic material-bound, and residual fractions) to reduce the toxicity of Cr(VI) and that surface sorption and reduction were dominant mechanisms for Cr(VI) immobilization. CMC-FeS@biochar greatly reduced the bioavailability of Cr(VI) to wheat and earthworms (Eisenia fetida). Moreover, the application of CMC-FeS@biochar enhanced soil organic matter content and microbial activity. This work highlighted the potential of CMC-FeS@biochar composite as a low-cost, "green", and effective amendment for immobilizing Cr(VI) in contaminated soils and improving soil properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Long-term stability of FeSO4 and H2SO4 treated chromite ore processing residue (COPR): Importance of H+ and SO42.

PubMed

Wang, Xin; Zhang, Jingdong; Wang, Linling; Chen, Jing; Hou, Huijie; Yang, Jiakuan; Lu, Xiaohua

2017-01-05

In this study, the long-term stability of Cr(VI) in the FeSO 4 and H 2 SO 4 (FeSO 4 -H 2 SO 4 ) treated chromite ore processing residue (COPR) after 400 curing days and the stabilization mechanisms were investigated. FeSO 4 -H 2 SO 4 treatment significantly reduced toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) Cr(VI) concentrations to lower than the regulatory limit of 1.5mgL -1 (HJ/T 301-2007, China EPA) even for the samples curing 400days, achieving an outstanding long-term stability. Our independent leaching tests revealed that H + and SO 4 2- have synergistic effect on promoting the release of Cr(VI), which would make Cr(VI) easier accessed by Fe(II) during stabilization. The contributions of H + and SO 4 2- to Cr(VI) release ratio were 25%-44% and 19%-38%, respectively, as 5mol H 2 SO 4 per kg COPR was used. X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and alkaline digestion analyses were also employed to interpret the possible stabilization mechanism. Cr(VI) released from COPR solid was reduced to Cr(III) by Fe(II), and then formed stable Fe x Cr (1-x) (OH) 3 precipitate. This study provides a facile and reliable scheme for COPR stabilization, and verifies the excellent long-term stability of the FeSO 4 -H 2 SO 4 treated COPR. Copyright © 2016 Elsevier B.V. All rights reserved.

45 CFR 84.61 - Procedures.

Code of Federal Regulations, 2013 CFR

2013-10-01

... provisions applicable to title VI of the Civil Rights Act of 1964 apply to this part. These procedures are... 45 Public Welfare 1 2013-10-01 2013-10-01 false Procedures. 84.61 Section 84.61 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION NONDISCRIMINATION ON THE BASIS OF HANDICAP IN...

45 CFR 84.61 - Procedures.

Code of Federal Regulations, 2011 CFR

2011-10-01

... provisions applicable to title VI of the Civil Rights Act of 1964 apply to this part. These procedures are... 45 Public Welfare 1 2011-10-01 2011-10-01 false Procedures. 84.61 Section 84.61 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION NONDISCRIMINATION ON THE BASIS OF HANDICAP IN...

45 CFR 84.61 - Procedures.

Code of Federal Regulations, 2012 CFR

2012-10-01

... provisions applicable to title VI of the Civil Rights Act of 1964 apply to this part. These procedures are... 45 Public Welfare 1 2012-10-01 2012-10-01 false Procedures. 84.61 Section 84.61 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION NONDISCRIMINATION ON THE BASIS OF HANDICAP IN...

45 CFR 84.61 - Procedures.

Code of Federal Regulations, 2014 CFR

2014-10-01

... provisions applicable to title VI of the Civil Rights Act of 1964 apply to this part. These procedures are... 45 Public Welfare 1 2014-10-01 2014-10-01 false Procedures. 84.61 Section 84.61 Public Welfare Department of Health and Human Services GENERAL ADMINISTRATION NONDISCRIMINATION ON THE BASIS OF HANDICAP IN...

22 CFR 142.70 - Procedures.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Procedures. 142.70 Section 142.70 Foreign Relations DEPARTMENT OF STATE CIVIL RIGHTS NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR... applicable to title VI of the Civil Rights Act of 1964 apply to this part. These procedures are found in 22...

22 CFR 142.70 - Procedures.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Procedures. 142.70 Section 142.70 Foreign Relations DEPARTMENT OF STATE CIVIL RIGHTS NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR... applicable to title VI of the Civil Rights Act of 1964 apply to this part. These procedures are found in 22...

22 CFR 142.70 - Procedures.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Procedures. 142.70 Section 142.70 Foreign Relations DEPARTMENT OF STATE CIVIL RIGHTS NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR... applicable to title VI of the Civil Rights Act of 1964 apply to this part. These procedures are found in 22...

22 CFR 142.70 - Procedures.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Procedures. 142.70 Section 142.70 Foreign Relations DEPARTMENT OF STATE CIVIL RIGHTS NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR... applicable to title VI of the Civil Rights Act of 1964 apply to this part. These procedures are found in 22...

22 CFR 142.70 - Procedures.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Procedures. 142.70 Section 142.70 Foreign Relations DEPARTMENT OF STATE CIVIL RIGHTS NONDISCRIMINATION ON THE BASIS OF HANDICAP IN PROGRAMS OR... applicable to title VI of the Civil Rights Act of 1964 apply to this part. These procedures are found in 22...

Speciation of chromium (VI) and total chromium determination in welding dust samples by flow-injection analysis coupled to atomic absorption spectrometry.

PubMed

Girard, L; Hubert, J

1996-11-01

We have studied the speciation of chromium (VI) in stainless-steel welding dusts. The approach used for the analysis of Cr(VI) and total Cr relies on a flow-injection analyzer (FIA) equipped with two different sequential detectors. The system measures Cr(VI). by colorimetry (with 1,5-diphenyl carbohydrazide) and total chromium content by flame atomic absorption spectroscopy (AAS). The extraction of the samples of welding-fume dusts is achieved in a buffer solution (acetic acid and sodium acetate at pH 4). This extraction procedure gives a 96% recovery of chromium (VI). The FIA-AAS system that has been described is also more sensitive, has a lower detection limit (0.005 mug ml(-1)) and gives a better precision (< 1%) than other equivalent systems that have been previously described.

40 CFR 1066.815 - Exhaust emission test procedures for FTP testing.

Code of Federal Regulations, 2014 CFR

2014-07-01

... must meet the requirements related to filter face velocity as described in 40 CFR 1065.170(c)(1)(vi..., set the filter face velocity to a weighting target of 1.0 to meet the requirements of 40 CFR 1065.170(c)(1)(vi). Allow filter face velocity to decrease as a percentage of the weighting factor if the...

Evaluation of on-line desalter-inductively coupled plasma-mass spectrometry system for determination of Cr(III), Cr(VI), and total chromium concentrations in natural water and urine samples

NASA Astrophysics Data System (ADS)

Sun, Y. C.; Lin, C. Y.; Wu, S. F.; Chung, Y. T.

2006-02-01

We have developed a simple and convenient method for the determination of Cr(III), Cr(VI), and the total chromium concentrations in natural water and urine samples that use a flow injection on-line desalter-inductively coupled plasma-mass spectrometry system. When using aqueous ammonium chloride (pH 8) as the stripping solution, the severe interference from sodium in the matrix can be eliminated prior to inductively coupled plasma-mass spectrometry measurement, and the Cr(VI) level can be determined directly. To determine the total concentration of Cr in natural water and urine samples, we used H 2O 2 or HNO 3 to decompose the organic matter and convert all chromium species into the Cr(VI) oxidation state. To overcome the spectral interference caused by the matrix chloride ion in the resulting solutions, we employed cool plasma to successfully suppress chloride-based molecular ion interference during the inductively coupled plasma-mass spectrometry measurement. By significantly eliminating interference from the cationic and anionic components in the matrices prior to the inductively coupled plasma-mass spectrometry measurement, we found that the detection limit reached 0.18 μg L - 1 (based on 3 sigma). We validated this method through the analysis of the total chromium content in two reference materials (NIST 1643c and 2670E) and through measuring the recovery in spiked samples.

Intracellular chromium localization and cell physiological response in the unicellular alga Micrasterias

PubMed Central

Volland, Stefanie; Lütz, Cornelius; Michalke, Bernhard; Lütz-Meindl, Ursula

2012-01-01

Various contaminants like metals and heavy metals are constantly released into the environment by anthropogenic activities. The heavy metal chromium has a wide industrial use and exists in two stable oxidation states: trivalent and hexavalent. Chromium can cause harm to cell metabolism and development, when it is taken up by plants instead of necessary micronutrients such as for example iron. The uptake of Cr VI into plant cells has been reported to be an active process via carriers of essential anions, while the cation Cr III seems to be taken up inactively. Micrasterias denticulata, an unicellular green alga of the family Desmidiaceae is a well-studied cell biological model organism. Cr III and VI had inhibiting effects on its cell development, while cell division rates were only impaired by Cr VI. Transmission electron microscopy (TEM) revealed ultrastructural changes such as increased vacuolization, condensed cytoplasm and dark precipitations in the cell wall after 3 weeks of Cr VI treatment. Electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) were applied to measure intracellular chromium distribution. Chromium was only detected after 3 weeks of 10 μM Cr VI treatment in electron dense precipitations found in bag-like structures along the inner side of the cell walls together with iron and elevated levels of oxygen, pointing toward an accumulation respectively extrusion of chromium in form of an iron–oxygen compound. Atomic emission spectroscopy (EMS) revealed that Micrasterias cells are able to accumulate considerable amounts of chromium and iron. During chromium treatment the Cr:Fe ratio shifted in favor of chromium, which implied that chromium may be taken up instead of iron. Significant and rapid increase of ROS production within the first 5 min of treatment confirms an active Cr VI uptake. SOD and CAT activity after Cr VI treatment did not show a response, while the glutathione pool determined by immuno-TEM decreased significantly in chromium treated cells, showing that glutathione is playing a major role in intracellular ROS and chromium detoxification. PMID:22204989

Crystal structure of the new A2SnTa6X18 (A = K, Rb, Cs; X = Cl, Br) cluster compounds

NASA Astrophysics Data System (ADS)

Lemoine, P.; Wilmet, M.; Malaman, B.; Paofai, S.; Dumait, N.; Cordier, S.

2018-01-01

The crystal structure of the new cluster compounds A2SnTa6X18 (with A = K, Rb, Cs, and X = Cl, Br) was determined by using single-crystal and powder X-ray diffraction, and 119Sn Mössbauer spectroscopy. Those compounds crystallize in the Cs2EuNb6Br18-type structure of space group R 3 ̅. This type of structure is built up on discrete edge-bridged [M6Xi12Xa6]4- cluster units arranged according to a pseudo face-centered cubic stacking, where the octahedral and tetrahedral vacancies are fully occupied by divalent tin cations and monovalent alkaline cations, respectively. The tin cations influence on the halogen matrix and the electronic effects on the cluster units in the Cs2EuNb6Br18-type structure are discussed by comparison with isotype compounds. From those analyses, the ionic radius of Sn2+ in coordination number VI is estimated to be 1.14(1) Å. Finally, K2SnTa6Br18 might be considered as a new example of compound containing a quite bare stannous ion (5 s2 configuration).

Ruling out Virtual Impactors with Negative Observations

NASA Astrophysics Data System (ADS)

Milani, A.; Chesley, S. R.; Boattini, A.; Valsecchi, G. B.

1999-09-01

If, for an asteroid which has been observed only over a short arc then lost, there are orbits compatible with the observations resulting in collisions, recovery would be desirable to decide if it will actually impact. If recovery is essentially impractical, as is the case for many small asteroids in the 100 m to 500 m diameter range, the next best thing is to make sure that the lost asteroid is not on a collision course. We propose a method to achieve this guarantee, with an observational effort far smaller than the one required for recovery. The procedure involves the computation of an orbit which is compatible with the available observations and, by hypothesis, results in an impact at some later encounter; this we call a Virtual Impactor (VI). The collision at some future time is a strong constraint, thus the VI has a well determined orbit. We show that it is possible to compute for each given time of observation the skyprint of the VI, that is the set of astrometric positions compatible with an impact (or a near impact). The skyprint needs to be scanned by powerful enough telescopes to perform a negative observation; once this has been done for the skyprints of all VIs, collisions can be excluded even without recovery. We propose to apply this procedure to the case of the lost asteroid 1998 OX_4, for which we have found orbital solutions with impacts in the years 2014, 2038, 2044 and 2046. Suitable observing windows are found when the VI would be close to the Earth in 2001 and in 2003, and the corresponding skyprints are small enough to be covered with very few frames. This procedure might become more and more necessary in the future, as the number of discoveries of small potentially hazardous asteroids increases; we discuss the general principles and the validation procedures that should apply to such a VI removal campaign. This research has been funded by the Italian Space Agency (ASI), by a NATO fellowship, by Consiglio Nazionale delle Ricerche (CNR), by the University of Pisa, and by the Spaceguard Foundation.

Modeling hexavalent chromium removal in a Bacillus sp. fixed-film bioreactor.

PubMed

Nkhalambayausi-Chirwa, Evans M; Wang, Yi-Tin

2004-09-30

A one-dimensional diffusion-reaction model was developed to simulate Cr(VI) reduction in a Bacillus sp. pure culture biofilm reactor with glucose as a sole supplied carbon and energy source. Substrate utilization and Cr(VI) reduction in the biofilm was best represented by a system of (second-order) partial differential equations (PDEs). The PDE system was solved by the (fourth-order) Runge-Kutta method adjusted for mass transport resistance using the (second-order) Crank-Nicholson and Backward Euler finite difference methods. A heuristic procedure (genetic search algorithm) was used to find global optimum values of Cr(VI) reduction and substrate utilization rate kinetic parameters. The fixed-film bioreactor system yielded higher values of the maximum specific Cr(VI) reduction rate coefficient and Cr(VI) reduction capacity (kmc = 0.062 1/h, and Rc = 0.13 mg/mg, respectively) than previously determined in batch reactors (kmc = 0.022 1/h and Rc = 0.012 mg/mg). The model predicted effluent Cr(VI) concentration well with 98.9% confidence (sigmay2 = 2.37 mg2/L2, N = 119) and effluent glucose with 96.4 % confidence (sigmay(w)2 = 5402 mg2/L2, N = 121, w = 100) over a wide range of Cr(VI) loadings (10-498 mg Cr(VI)/L/d). Copyright 2004 Wiley Periodicals, Inc.

ViSimpl: Multi-View Visual Analysis of Brain Simulation Data

PubMed Central

Galindo, Sergio E.; Toharia, Pablo; Robles, Oscar D.; Pastor, Luis

2016-01-01

After decades of independent morphological and functional brain research, a key point in neuroscience nowadays is to understand the combined relationships between the structure of the brain and its components and their dynamics on multiple scales, ranging from circuits of neurons at micro or mesoscale to brain regions at macroscale. With such a goal in mind, there is a vast amount of research focusing on modeling and simulating activity within neuronal structures, and these simulations generate large and complex datasets which have to be analyzed in order to gain the desired insight. In such context, this paper presents ViSimpl, which integrates a set of visualization and interaction tools that provide a semantic view of brain data with the aim of improving its analysis procedures. ViSimpl provides 3D particle-based rendering that allows visualizing simulation data with their associated spatial and temporal information, enhancing the knowledge extraction process. It also provides abstract representations of the time-varying magnitudes supporting different data aggregation and disaggregation operations and giving also focus and context clues. In addition, ViSimpl tools provide synchronized playback control of the simulation being analyzed. Finally, ViSimpl allows performing selection and filtering operations relying on an application called NeuroScheme. All these views are loosely coupled and can be used independently, but they can also work together as linked views, both in centralized and distributed computing environments, enhancing the data exploration and analysis procedures. PMID:27774062

ViSimpl: Multi-View Visual Analysis of Brain Simulation Data.

PubMed

Galindo, Sergio E; Toharia, Pablo; Robles, Oscar D; Pastor, Luis

2016-01-01

After decades of independent morphological and functional brain research, a key point in neuroscience nowadays is to understand the combined relationships between the structure of the brain and its components and their dynamics on multiple scales, ranging from circuits of neurons at micro or mesoscale to brain regions at macroscale. With such a goal in mind, there is a vast amount of research focusing on modeling and simulating activity within neuronal structures, and these simulations generate large and complex datasets which have to be analyzed in order to gain the desired insight. In such context, this paper presents ViSimpl, which integrates a set of visualization and interaction tools that provide a semantic view of brain data with the aim of improving its analysis procedures. ViSimpl provides 3D particle-based rendering that allows visualizing simulation data with their associated spatial and temporal information, enhancing the knowledge extraction process. It also provides abstract representations of the time-varying magnitudes supporting different data aggregation and disaggregation operations and giving also focus and context clues. In addition, ViSimpl tools provide synchronized playback control of the simulation being analyzed. Finally, ViSimpl allows performing selection and filtering operations relying on an application called NeuroScheme. All these views are loosely coupled and can be used independently, but they can also work together as linked views, both in centralized and distributed computing environments, enhancing the data exploration and analysis procedures.

Elimination of a pollution associated with chromic acid during the electro-deposition of Cr(III) using appropriate anodic and membrane materials in a double film bath.

PubMed

Jiang, Xiaojun; Chen, Wenchao; Xu, Hongbo

2009-01-01

A method using trivalent chromium has been used to replace hexavalent chromium for the electro-deposition of chromium. Using a tri-chamber bath system various anodic materials and membranes were evaluated to minimize the production of environmentally and health damaging chromic acid. By measuring the absorbance of Cr(VI) at 640 nm, the results indicate that the use of a titanium plated ruthenium (Ti-Ru) anode produces the least amount of chromic acid byproduct compared to lead-gold alloy and graphite anodes. The concentration of Cr(VI) in the immediate vicinity of the Ti-Ru anode decreased from 0.389 mg/L to 0 during a 40-min deposition period. The use of a Nafion(TM) quaternary cation exchange membrane portioning the buffer and anode selectively prevented Cr(III) from entering the anode compartment whilst allowing the migration of H(+) to maintain overall voltaic continuity. It has been demonstrated that the use of a Ti-Ru anode with a Nafion(TM) membrane can eliminate the production of chromic acid associated with the electro-deposition of chromium plate thereby preventing its health damaging exposure to plant operators and preventing discharge of Cr(VI) into the environment. Addition of a surfactant improved current efficiency by 34.7%.

Vermicomposting as an advanced biological treatment for industrial waste from the leather industry.

PubMed

Nunes, Ramom R; Bontempi, Rhaissa M; Mendonça, Giovane; Galetti, Gustavo; Rezende, Maria Olímpia O

2016-01-01

The leather industry (tanneries) generates high amounts of toxic wastes, including solid and liquid effluents that are rich in organic matter and mineral content. Vermicomposting was studied as an alternative method of treating the wastes from tanneries. Vermicompost was produced from the following tannery residues: tanned chips of wet-blue leather, sludge from a liquid residue treatment station, and a mixture of both. Five hundred earthworms (Eisenia fetida) were added to each barrel. During the following 135 days the following parameters were evaluated: pH, total organic carbon (TOC), organic matter (OM), cation exchange capacity (CEC), C:N ratio, and chromium content as Cr (III) and Cr (VI). The results for pH, TOC and OM contents showed decreases in their values during the composting process, whereas values for CEC and total nitrogen rose, indicating that the vermicompost reached maturity. For chromium, at 135 days, all values of Cr (VI) were below the detectable level. Therefore, the Cr (VI) content had probably been biologically transformed into Cr (III), confirming the use of this technique as an advanced biological treatment. The study reinforces the idea that vermicomposting could be introduced as an effective technology for the treatment of industrial tannery waste and the production of agricultural inputs.

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

PubMed

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

2012-03-30

Chromium plating used for functional purposes provides an extremely hard, wear and corrosion resistant layer by means of electrolytic deposition. Typical layer thicknesses range between 2.5 and 500 μm. Chromium electroplating baths contain high concentrations of Cr(VI) with chromium trioxide (CrO(3)) as the chromium source. When because of technical or economic reasons a bath gets exhausted, a waste containing mainly chromium as dichromate as well as other heavy metals is generated. Chromium may then be purified for use in other industrial processes with different requirements. In this work, a sustainable system for using galvanic wastes as reagents in the leather tanning industry, thus reducing quantity of wastes to be treated, is presented. Metal cations present in the chromium exhausted bath were precipitated with NaOH. Then, the solution containing mainly soluble Cr(VI) was separated. By means of sodium sulphite in acidic conditions, Cr(VI) was reduced to Cr(III) as chromium (III) sulphate. From chromium (III) sulphate a basic Cr(III) sulphate may be obtained, which is one of most used compounds in the tanning industry. Cr(III) concentration in the final solution allows its reuse without concentration, but with a slight dilution. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of Modeling Methods and Tools for Predicting Coupled Reactive Transport Processes in Porous Media at Multiple Scales

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

Clement, T. Prabhakar; Barnett, Mark O.; Zheng, Chunmiao

DE-FG02-06ER64213: Development of Modeling Methods and Tools for Predicting Coupled Reactive Transport Processes in Porous Media at Multiple Scales Investigators: T. Prabhakar Clement (PD/PI) and Mark O. Barnett (Auburn), Chunmiao Zheng (Univ. of Alabama), and Norman L. Jones (BYU). The objective of this project was to develop scalable modeling approaches for predicting the reactive transport of metal contaminants. We studied two contaminants, a radioactive cation [U(VI)] and a metal(loid) oxyanion system [As(III/V)], and investigated their interactions with two types of subsurface materials, iron and manganese oxyhydroxides. We also developed modeling methods for describing the experimental results. Overall, the project supportedmore » 25 researchers at three universities. Produced 15 journal articles, 3 book chapters, 6 PhD dissertations and 6 MS theses. Three key journal articles are: 1) Jeppu et al., A scalable surface complexation modeling framework for predicting arsenate adsorption on goethite-coated sands, Environ. Eng. Sci., 27(2): 147-158, 2010. 2) Loganathan et al., Scaling of adsorption reactions: U(VI) experiments and modeling, Applied Geochemistry, 24 (11), 2051-2060, 2009. 3) Phillippi, et al., Theoretical solid/solution ratio effects on adsorption and transport: uranium (VI) and carbonate, Soil Sci. Soci. of America, 71:329-335, 2007« less

76 FR 33999 - Spouse and Surviving Spouse; Technical Amendment

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-10

... procedure, Aged, Authority delegations, Blind, Buildings, Civil rights, Employment, Equal educational... Administrative practice and procedure, Armed forces, Civil rights, Claims, Colleges and universities, Conflict of...-ASSISTED PROGRAMS OF THE DEPARTMENT OF VETERANS AFFAIRS--EFFECTUATION OF TITLE VI OF THE CIVIL RIGHTS ACT...

Bifluoride-catalysed sulfur(VI) fluoride exchange reaction for the synthesis of polysulfates and polysulfonates

NASA Astrophysics Data System (ADS)

Gao, Bing; Zhang, Linda; Zheng, Qinheng; Zhou, Feng; Klivansky, Liana M.; Lu, Jianmei; Liu, Yi; Dong, Jiajia; Wu, Peng; Sharpless, K. Barry

2017-11-01

Polysulfates and polysulfonates possess exceptional mechanical properties making them potentially valuable engineering polymers. However, they have been little explored due to a lack of reliable synthetic access. Here we report bifluoride salts (Q+[FHF]-, where Q+ represents a wide range of cations) as powerful catalysts for the sulfur(VI) fluoride exchange (SuFEx) reaction between aryl silyl ethers and aryl fluorosulfates (or alkyl sulfonyl fluorides). The bifluoride salts are significantly more active in catalysing the SuFEx reaction compared to organosuperbases, therefore enabling much lower catalyst-loading (down to 0.05 mol%). Using this chemistry, we are able to prepare polysulfates and polysulfonates with high molecular weight, narrow polydispersity and excellent functional group tolerance. The process is practical with regard to the reduced cost of catalyst, polymer purification and by-product recycling. We have also observed that the process is not sensitive to scale-up, which is essential for its future translation from laboratory research to industrial applications.

Calculation of the electron structure of vacancies and their compensated states in III-VI semiconductors

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

Mehrabova, M. A., E-mail: Mehrabova@mail.ru; Madatov, R. S.

2011-08-15

The Green's functions theory and the bond-orbital model are used as a basis for calculations of the electron structure of local defects-specifically, vacancies and their compensated states in III-VI semiconductors. The energy levels in the band gap are established, and the changes induced in the electron densities in the GaS, GaSe, and InSe semiconductors by anion and cation vacancies and their compensated states are calculated. It is established that, if a vacancy is compensated by an atom of an element from the same subgroup with the same tetrahedral coordination and if the ionic radius of the compensating atom is smallermore » than that of the substituted atom, the local levels formed by the vacancy completely disappear. It is shown that this mechanism of compensation of vacancies provides a means not only for recovering the parameters of the crystal, but for improving the characteristics of the crystal as well.« less

Spectroscopic studies of Np(V) complexation

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

Stout, B.E.

The complexation of Np(V) with aliphatic (oxalic, malonic, succinic, glutaric, and maleic) and aromatic (phthalic, pyromellitic, hemimellitic, trimellitic, and mellitic) polycarboxylic acids was studied by spectrophotometry at 1 M ionic strength (NaClO{sub 4}) and 23 C. For the aliphatic systems, the stability of the neptunyl complexes was found to decrease as the carbon chain length of the ligand increased which was attributed to an entropy effect. In polycarboxylate systems, the stability constant decreased in the order hemimellitate > mellitate > pyromellitate > trimellitate, phthalate. With the exception of hemimellitate, this trend follows the order of decreasing basicity of the ligand.more » After correction of the stability constant for statistical effects, the stability of the mellitate, pyromellitate, trimellitate, and phthalate complexes were approximately the same. The unexpected strength the hemimellitate complexation was attributed to an increase in electron density at the binding site from the non-chelating carboxylate group through induction. The complexation of phthalate, trimellitate and hemimellitate and mellitate were studied as a function of pH. Trimellitate and mellitate were found to form ML as well as ML complexes while for phthalate and hemimellitate only ML species were observed. The stability constants of the cation-cation complexes Np(V)-U(VI) and Np(V)-Np(V), measured at 6 M ionic strength (HClO{sub 4}) and 25 C, were found to be 2.45 {+-} 0.05 and 1.41 {+-} 0.14, respectively. The change in enthalpy for the Np(V)-U(VI) system as determined by the measurement of the stability constant as function of temperature was -14.3 {+-} 1.6 kJ/mol.« less

45 CFR 83.20 - Interim procedures.

Code of Federal Regulations, 2014 CFR

2014-10-01

... sections 704 and 845 of the Act and other civil rights authorities administered by the Department, the procedural provisions applicable to title VI of the Civil Rights Act of 1964 are hereby adopted and... Welfare Department of Health and Human Services GENERAL ADMINISTRATION REGULATION FOR THE ADMINISTRATION...

45 CFR 83.20 - Interim procedures.

Code of Federal Regulations, 2013 CFR

2013-10-01

... sections 704 and 845 of the Act and other civil rights authorities administered by the Department, the procedural provisions applicable to title VI of the Civil Rights Act of 1964 are hereby adopted and... Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION REGULATION FOR THE ADMINISTRATION...

45 CFR 83.20 - Interim procedures.

Code of Federal Regulations, 2011 CFR

2011-10-01

... sections 704 and 845 of the Act and other civil rights authorities administered by the Department, the procedural provisions applicable to title VI of the Civil Rights Act of 1964 are hereby adopted and... Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION REGULATION FOR THE ADMINISTRATION...

45 CFR 83.20 - Interim procedures.

Code of Federal Regulations, 2010 CFR

2010-10-01

... sections 704 and 845 of the Act and other civil rights authorities administered by the Department, the procedural provisions applicable to title VI of the Civil Rights Act of 1964 are hereby adopted and... Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION REGULATION FOR THE ADMINISTRATION...

45 CFR 83.20 - Interim procedures.

Code of Federal Regulations, 2012 CFR

2012-10-01

... sections 704 and 845 of the Act and other civil rights authorities administered by the Department, the procedural provisions applicable to title VI of the Civil Rights Act of 1964 are hereby adopted and... Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION REGULATION FOR THE ADMINISTRATION...

12 CFR 225.8 - Capital planning.

Code of Federal Regulations, 2012 CFR

2012-01-01

... this section; (C) A discussion of the results of any stress test required by law or regulation, and an... policies and procedures, including risk management policies and procedures; (v) The bank holding company's liquidity profile and management; and (vi) Any other relevant qualitative or quantitative information...

Determination of chromium (VI) in primary and secondary fertilizer and their respective precursors.

PubMed

Krüger, Oliver; Fiedler, Francesca; Adam, Christian; Vogel, Christian; Senz, Rainer

2017-09-01

Hexavalent chromium species (Cr(VI)) are often carcinogenic, of high acute toxicity, highly mobile, and thus pose a severe risk to health and environment. Fertilizers usually contain significant amounts of chromium. Therefore, a reliable analysis of chromium and the fraction of Cr(VI) are crucial for safe use of fertilizers. This problem is expected to increase in the future, since more and more recycled fertilizers emerge due to increasing fertilizer demand and respective supply risks. However, existing analytical methods have been developed for conventional fertilizers and have to be tested whether they are suitable for the new materials. Thus, we performed a wet-chemical extraction for Cr(VI) on several matrices as well as respective quality control experiments including spiking with Cr(III) and Cr(VI) compounds. We found the Cr(VI) amounts to be below 2 mg/kg except for a thermally post-treated sewage sludge ash (SSA) that showed 12.3 mg/kg. The presence of organic matter e.g. in sludge or precipitated struvite caused a reduction of spiked Cr(VI) and thus no satisfying recovery for quality control. Cr(VI) reduction was also observed for SSA, presumably due to the presence of Fe(II) compounds. Even though the tested procedure can be hampered in some recycled fertilizer matrices, it might be adapted to be applicable also for these complex samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Catalano, Jeffrey G.; Giammar, Daniel E.; Wang, Zheming

Phosphate addition is an in situ remediation approach that may enhance the sequestration of uranium without requiring sustained reducing conditions. However, the geochemical factors that determine the dominant immobilization mechanisms upon phosphate addition are insufficiently understood to design efficient remediation strategies or accurately predict U(VI) transport. The overall objective of our project is to determine the dominant mechanisms of U(VI)-phosphate reactions in subsurface environments. Our research approach seeks to determine the U(VI)-phosphate solid that form in the presence of different groundwater cations, characterize the effects of phosphate on U(VI) adsorption and precipitation on smectite and iron oxide minerals, examples ofmore » two major reactive mineral phases in contaminated sediments, and investigate how phosphate affects U(VI) speciation and fate during water flow through sediments from contaminated sites. The research activities conducted for this project have generated a series of major findings. U(VI) phosphate solids from the autunite mineral family are the sole phases to form during precipitation, with uranyl orthophosphate not occurring despite its predicted greater stability. Calcium phosphates may take up substantial quantities of U(VI) through three different removal processes (adsorption, coprecipitation, and precipitation) but the dominance of each process varies with the pathway of reaction. Phosphate co-adsorbs with U(VI) onto smectite mineral surfaces, forming a mixed uranium-phosphate surface complex over a wide range of conditions. However, this molecular-scale association of uranium and phosphate has not effect on the overall extent of uptake. In contrast, phosphate enhanced U(VI) adsorption to iron oxide minerals at acidic pH conditions but suppresses such adsorption at neutral and alkaline pH, despite forming mixed uranium-phosphate surface complexes during adsorption. Nucleation barriers exist that inhibit U(VI) phosphate solids from precipitating in the presence of smectite and iron oxide minerals as well as sediments from contaminated sites. Phosphate addition enhances retention of U(VI) by sediments from the Rifle, CO and Hanford, WA field research sites, areas containing substantial uranium contamination of groundwater. This enhanced retention is through adsorption processes. Both fast and slow uptake and release behavior is observed, indicating that diffusion of uranium between sediment grains has a substantial effect of U(VI) fate in flowing groundwater systems. This project has revealed the complexity of U(VI)-phosphate reactions in subsurface systems. Distinct chemical processes occur in acidic and alkaline groundwater systems. For the latter, calcium phosphate formation, solution complexation, and competition between phosphate and uranium for adsorption sites may serve to either enhance or inhibit U(VI) removal from groundwater. Under the groundwater conditions present at many contaminated sites in the U.S., phosphate appears to general enhance U(VI) retention and limit transport. However, formation of low-solubility uranium phosphate solids does not occur under field-relevant conditions, despite this being the desired product of phosphate-based remediation approaches. In addition, simple equilibrium approaches fail to well-predict uranium fate in contaminated sediments amended with phosphate, with reactive transport models that include reaction rates and mass transport through occluded domains needed to properly describe the system. Phosphate addition faces challenges to being effective as a stand-alone groundwater treatment approach but would prove beneficial as an add-on to other treatment methods that will further limit uranium migration in the subsurface.« less

Quantitative Evaluation of E1 Endoglucanase Recovery from Tobacco Leaves Using the Vacuum Infiltration-Centrifugation Method

PubMed Central

Kingsbury, Nathaniel J.; McDonald, Karen A.

2014-01-01

As a production platform for recombinant proteins, plant leaf tissue has many advantages, but commercialization of this technology has been hindered by high recovery and purification costs. Vacuum infiltration-centrifugation (VI-C) is a technique to obtain extracellularly-targeted products from the apoplast wash fluid (AWF). Because of its selective recovery of secreted proteins without homogenizing the whole tissue, VI-C can potentially reduce downstream production costs. Lab scale experiments were conducted to quantitatively evaluate the VI-C method and compared to homogenization techniques in terms of product purity, concentration, and other desirable characteristics. From agroinfiltrated Nicotiana benthamiana leaves, up to 81% of a truncated version of E1 endoglucanase from Acidothermus cellulolyticus was recovered with VI-C versus homogenate extraction, and average purity and concentration increases of 4.2-fold and 3.1-fold, respectively, were observed. Formulas were developed to predict recovery yields of secreted protein obtained by performing multiple rounds of VI-C on the same leaf tissue. From this, it was determined that three rounds of VI-C recovered 97% of the total active recombinant protein accessible to the VI-C procedure. The results suggest that AWF recovery is an efficient process that could reduce downstream processing steps and costs for plant-made recombinant proteins. PMID:24971334

Effects of increasing number of rings on the ion sensing ability of CdSe quantum dots: a theoretical study

NASA Astrophysics Data System (ADS)

Malik, Pragati; Kakkar, Rita

2018-04-01

A computational study on the structural and electronic properties of a special class of artificial atoms, known as quantum dots, has been carried out. These are semiconductors with unique optical and electronic properties and have been widely used in various applications, such as bio-sensing, bio-imaging, and so on. We have considered quantum dots belonging to II-VI types of semiconductors, due to their wide band gap, possession of large exciton binding energies and unique optical and electronic properties. We have studied their applications as chemical ion sensors by beginning with the study of the ion sensing ability of (CdSe) n ( n = 3, 6, 9 which are in the size range of 0.24, 0.49, 0.74 nm, respectively) quantum dots for cations of the zinc triad, namely Zn2+, Cd2+, Hg2+, and various anions of biological and environmental importance, and studied the effect of increasing number of rings on their ion sensing ability. The various structural, electronic, and optical properties, their interaction energies, and charge transfer on interaction with metal ions and anions have been calculated and reported. Our studies indicate that the CdSe quantum dots can be employed as sensors for both divalent cations and anions, but they can sense cations better than anions.

Grounds Maintenance Equipment and Procedures. Building Maintenance. Module VI. Instructor's Guide.

ERIC Educational Resources Information Center

Crank, Virgil

This curriculum guide, one of six modules keyed to the building maintenance competency profile developed by industry and education professionals, provides materials for two units on grounds maintenance equipment and procedures. The first unit deals with grounds maintenance equipment and includes the following lessons: safety; changing oil/filter…

Title VI-B, Education of the Handicapped Act Annual Program Plan Fiscal Year 1979-Kansas State Department of Education.

ERIC Educational Resources Information Center

Kansas State Dept. of Education, Topeka.

The Kansas state plan for FY 1979 includes information on the following topics: full educational opportunities goal, policy on priorities, child identification, personnel development, individualized education program, procedural safeguards, least restrictive environment, protection in evaluation procedures, participation of private school…

29 CFR 95.44 - Procurement procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... 29 Labor 1 2014-07-01 2013-07-01 true Procurement procedures. 95.44 Section 95.44 Labor Office of the Secretary of Labor GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND...

29 CFR 95.44 - Procurement procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... 29 Labor 1 2013-07-01 2013-07-01 false Procurement procedures. 95.44 Section 95.44 Labor Office of the Secretary of Labor GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND...

29 CFR 95.44 - Procurement procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... 29 Labor 1 2012-07-01 2012-07-01 false Procurement procedures. 95.44 Section 95.44 Labor Office of the Secretary of Labor GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND...

Kinetic and equilibrium characterization of uranium(VI) adsorption onto carboxylate-functionalized poly(hydroxyethylmethacrylate)-grafted lignocellulosics.

PubMed

Anirudhan, T S; Divya, L; Suchithra, P S

2009-01-01

This study investigated the feasibility of using a new adsorbent prepared from coconut coir pith, CP (a coir industry-based lignocellulosic residue), for the removal of uranium [U(VI)] from aqueous solutions. The adsorbent (PGCP-COOH) having a carboxylate functional group at the chain end was synthesized by grafting poly(hydroxyethylmethacrylate) onto CP using potassium peroxydisulphate-sodium thiosulphite as a redox initiator and in the presence of N,N'-methylenebisacrylamide as a crosslinking agent. IR spectroscopy results confirm the graft copolymer formation and carboxylate functionalization. XRD studies confirm the decrease of crystallinity in PGCP-COOH compared to CP, and it favors the protrusion of the functional group into the aqueous medium. The thermal stability of the samples was studied using thermogravimetry (TG). Surface charge density of the samples as a function of pH was determined using potentiometric titration. The ability of PGCP-COOH to remove U(VI) from aqueous solutions was assessed using a batch adsorption technique. The maximum adsorption capacity was observed at the pH range 4.0-6.0. Maximum removal of 99.2% was observed for an initial concentration of 25mg/L at pH 6.0 and an adsorbent dose of 2g/L. Equilibrium was achieved in approximately 3h. The experimental kinetic data were analyzed using a first-order kinetic model. The temperature dependence indicates an endothermic process. U(VI) adsorption was found to decrease with an increase in ionic strength due to the formation of outer-sphere surface complexes on PGCP-COOH. Equilibrium data were best modeled by the Langmuir isotherm. The thermodynamic parameters such as DeltaG(0), DeltaH(0) and DeltaS(0) were derived to predict the nature of adsorption. Adsorption experiments were also conducted using a commercial cation exchanger, Ceralite IRC-50, with carboxylate functionality for comparison. Utility of the adsorbent was tested by removing U(VI) from simulated nuclear industry wastewater. Adsorbed U(VI) ions were desorbed effectively (about 96.2+/-3.3%) by 0.1M HCl. The adsorbent was suitable for repeated use (more than four cycles) without any noticeable loss of capacity.

Use of the vector index and geographic information system to prospectively inform West Nile virus interventions.

PubMed

Jones, Roderick C; Weaver, Kingsley N; Smith, Shamika; Blanco, Claudia; Flores, Cristina; Gibbs, Kevin; Markowski, Daniel; Mutebi, John-Paul

2011-09-01

We sought to estimate West Nile virus (WNV) activity in mosquito populations weekly at the census tract level in Chicago, IL, and to provide this information graphically. Each week we calculated a vector index (VI) for each mosquito trap then generated tract estimates using geographic information systems. During June 29-September 13, 2008, a median of 527 (60%) of 874 possible tracts per week had a VI value. Overall, 94% of the weekly VI tract estimates were 0; among those with a VI estimate greater than 0, the median was 0.33 (range 0.003-3.5). Officials deemed risk levels and weather conditions appropriate for adulticide treatments on 3 occasions, resulting in the treatment of approximately 252 linear kilometers of residential streets and alleys. Our analysis successfully converted complex, raw surveillance data into a format that highlighted areas of elevated WNV activity and facilitated the determination of appropriate response procedures.

41 CFR 105-72.504 - Procurement procedures.

Code of Federal Regulations, 2014 CFR

2014-01-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... Regulations System (Continued) GENERAL SERVICES ADMINISTRATION Regional Offices-General Services...

41 CFR 105-72.504 - Procurement procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... Regulations System (Continued) GENERAL SERVICES ADMINISTRATION Regional Offices-General Services...

41 CFR 105-72.504 - Procurement procedures.

Code of Federal Regulations, 2011 CFR

2011-01-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... Regulations System (Continued) GENERAL SERVICES ADMINISTRATION Regional Offices-General Services...

41 CFR 105-72.504 - Procurement procedures.

Code of Federal Regulations, 2012 CFR

2012-01-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... Regulations System (Continued) GENERAL SERVICES ADMINISTRATION Regional Offices-General Services...

40 CFR 30.44 - Procurement procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... metric system of measurement. (vi) Preference, to the extent practicable and economically feasible, for... UNIFORM ADMINISTRATIVE REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION...

40 CFR 30.44 - Procurement procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... metric system of measurement. (vi) Preference, to the extent practicable and economically feasible, for... UNIFORM ADMINISTRATIVE REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION...

40 CFR 30.44 - Procurement procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... metric system of measurement. (vi) Preference, to the extent practicable and economically feasible, for... UNIFORM ADMINISTRATIVE REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION...

40 CFR 30.44 - Procurement procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... metric system of measurement. (vi) Preference, to the extent practicable and economically feasible, for... UNIFORM ADMINISTRATIVE REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION...

Gadolinium and didymium (praseodymium/neodymium) cations as capture agents in lightmicroscopical histochemistry of acid and alkaline phosphatase.

PubMed

Halbhuber, K J; Zimmermann, N

1987-01-01

In previous papers, cerium and lanthanum based methods for light-microscopical detection of acid and alkaline phosphatase activity were proposed. In this paper, the usefulness of other lanthanide cations such as gadolinium and praseodymium/neodymium cations as capture agents in phosphatase histochemistry is tested. It is evident that phosphate ions were sufficiently trapped by these cations. According to the lead and silver multistep procedures earlier described it is possible to visualize alkaline phosphatase activity in the brush borders of the intestine or kidney as well as acid phosphatase activity in the lysosomes. These methods can be recommended.

Remediation of hexavalent chromium spiked soil by using synthesized iron sulfide particles.

PubMed

Li, Yujie; Wang, Wanyu; Zhou, Liqiang; Liu, Yuanyuan; Mirza, Zakaria A; Lin, Xiang

2017-02-01

Carboxymethyl cellulose (CMC) stabilized microscale iron sulfide (FeS) particles were synthesized and applied to remediate hexavalent chromium (Cr(VI)) spiked soil. The effects of parameters including dosage of FeS particles, soil moisture, and natural organic matter (NOM) in soil were investigated with comparison to iron sulfate (FeSO 4 ). The results show that the stabilized FeS particles can reduce Cr(VI) and immobilize Cr in soil quickly and efficiently. The soil moisture ranging from 40% to 70% and NOM in soil had no significant effects on Cr(VI) remediation by FeS particles. When molar ratio of FeS to Cr(VI) was 1.5:1, about 98% of Cr(VI) in soil was reduced by FeS particles in 3 d and Cr(VI) concentration decreased from 1407 mg kg -1 to 16 mg kg -1 . The total Cr and Cr(VI) in Toxicity Characteristic Leaching Procedure (TCLP) leachate were reduced by 98.4% and 99.4%, respectively. In FeS particles-treated soil, the exchangeable Cr fraction was mainly converted to Fe-Mn oxides bound fraction because of the precipitation of Cr(III)-Fe(III) hydroxides. The physiologically based extraction test (PBET) bioaccessibility of Cr was decreased from 58.67% to 6.98%. Compared to FeSO 4 , the high Cr(VI) removal and Cr immobilization efficiency makes prepared FeS particles a great potential in field application of Cr(VI) contaminated soil remediation. Copyright © 2016 Elsevier Ltd. All rights reserved.

32 CFR 32.44 - Procurement procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... REGULATIONS ADMINISTRATIVE REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION...

36 CFR 1210.44 - Procurement procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Procurement Standards...

32 CFR 32.44 - Procurement procedures.

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2011-07-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... REGULATIONS ADMINISTRATIVE REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION...

32 CFR 32.44 - Procurement procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... REGULATIONS ADMINISTRATIVE REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION...

36 CFR 1210.44 - Procurement procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Procurement Standards...

36 CFR 1210.44 - Procurement procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Procurement Standards...

32 CFR 32.44 - Procurement procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... REGULATIONS ADMINISTRATIVE REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION...

Optimizing the application of magnetic nanoparticles in Cr(VI) removal

NASA Astrophysics Data System (ADS)

Simeonidis, Konstantinos; Kaprara, Efthymia; Mitrakas, Manassis; Tziomaki, Magdalini; Angelakeris, Mavroidis; Vourlias, Georgios; Andritsos, Nikolaos

2013-04-01

The presence of heavy metals in aqueous systems is an intense health and environmental problem as implied by their harmful effects on human and other life forms. Among them, chromium is considered as an acutely hazardous compound contaminating the surface water from industrial wastes or entering the groundwater, the major source of drinking water, by leaching of chromite rocks. Chromium occurs in two stable oxidation states, Cr(III) and Cr(VI), with the hexavalent form being much more soluble and mobile in water having the ability to enter easily into living tissues or cells and thus become more toxic. Despite the established risks from Cr(VI)-containing water consumption and the increasing number of incidents, the E.U. tolerance limit for total chromium in potable water still stands at 50 μg/L. However, in the last years a worldwide debate concerning the establishment of a separate and very strict limit for the hexavalent form takes place. In practice, Cr(VI) is usually removed from water by various methods such as chemical coagulation/filtration, ion exchange, reverse osmosis and adsorption. Adsorption is considered as the simplest method which may become very effective if the process is facilitated by the incorporation of a Cr(VI) to Cr(III) reduction stage. This work studies the potential of using magnetic nanoparticles as adsorbing agents for Cr(VI) removal at the concentration levels met in contaminated drinking water. A variety of nanoparticles consisting of ferrites MFe2O4 (M=Fe, Co, Ni, Cu, Mn, Mg, Zn) were prepared by precipitating the corresponding bivalent or trivalent sulfate salts under controlled acidity and temperature. Electron microscopy and X-ray diffraction techniques were used to verify their crystal structure and determine the morphological characteristics. The mean particle size of the samples was found in the range 10-50 nm. Batch Cr(VI) removal tests were performed in aqueous nanoparticles dispersions showing the efficiency of ferrite nanoparticles to reduce Cr(VI) concentration below the regulation limit. The removal capacity is maximized for Fe3O4 nanoparticles due to the high reducing potential of the Fe2+ cations. Furthermore, their applicability was tested in a pilot-scale magnetic separator for the continuous flow removal of nanoparticles after water treatment that takes advantage of the magnetic properties. Acknowledgment This work was implemented within the framework of the Action «Supporting Postdoctoral Researchers» of the Operational Program "Education and Lifelong Learning" (Action's Beneficiary: General Secretariat for Research and Technology), and is co-financed by the European Social Fund (ESF) and the Greek State.

Enrichment and low-level determination of glyphosate, aminomethylphosphonic acid and glufosinate in drinking water after cleanup by cation exchange resin.

PubMed

Küsters, Markus; Gerhartz, Michael

2010-04-01

For the determination of glyphosate, aminomethylphosphonic acid and glufosinate in drinking water, different procedures of enrichment and cleanup were examined using anion exchange or SPE. In many cases interactions of, e.g. alkaline earth metal ions especially calcium could be observed during enrichment and cleanup resulting in loss of analytes. For that reason, a novel cleanup and enrichment procedure for the determination of these phosphonic acid herbicides has been developed in drinking water using cation-exchange resin. In summary, the cleanup procedure with cation-exchange resin developed in this study avoids interactions as described above and is applicable to calcium-rich drinking water samples. After derivatization with 9-fluorenylmethylchloroformate followed by LC with fluorescence detection, LOD of 12, 14 and 12 ng/L and mean recoveries from real-world drinking water samples of 98+/-9, 100+/-16 and 101+/-11% were obtained for glyphosate, aminomethylphosphonic acid and glufosinate, respectively. The low LODs and the high precision permit the analysis of these phosphonic acid herbicides according to the guidelines of the European Commission.

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.

Enhanced removal of toxic Cr(VI) in tannery wastewater by photoelectrocatalysis with synthetic TiO2 hollow spheres

NASA Astrophysics Data System (ADS)

Zhao, Yang; Chang, Wenkai; Huang, Zhiding; Feng, Xugen; Ma, Lin; Qi, Xiaoxia; Li, Zenghe

2017-05-01

Owing to the acute toxicity and mobility, the Cr(VI) in tannery wastewater is a huge threat to biological and environmental systems. Herein, an effective photoelectrocatalytic reduction of Cr(VI) was carried out by applying electric field to photocatalysis of as-prepared TiO2 spheres. The synthesis of spherical TiO2 catalytic materials with hollow structure and high surface areas was based on a self-assembly process induced by a mixture of organic acetic acid and ethanol. The possible formation mechanism of TiO2 spheres was proposed and verified by acid concentration-dependent and temperature-dependent experiments. It was found that the reaction rate constant of photoelectrocatalytic reduction of Cr(VI) exhibited an almost 3 fold improvement (0.0362 min-1) as compared to that of photocatalysis (0.0126 min-1). As a result, the mechanism of photoelectrocatalytic reduction of Cr(VI) was described according to the simultaneous determination of Cr(VI), Cr(III) and total Cr in the system. In addition, the effect of pH value and voltage of potential were also discussed. Moreover, this photoelectrocatalysis with TiO2 hollow spheres exhibited excellent activity for reduction of Cr(VI) in actual tannery wastewater produced from three different tanning procedures. These attributes suggest that this photoelectrocatalysis has strong potential applications in the treatment of tannery pollutants.

Scheduling Capacitated One-Way Vehicles on Paths with Deadlines

NASA Astrophysics Data System (ADS)

Uchida, Jun; Karuno, Yoshiyuki; Nagamochi, Hiroshi

In this paper, we deal with a scheduling problem of minimizing the number of employed vehicles on paths. Let G=(V,E) be a path with a set V={vi|i=1,2,...,n} of vertices and a set E={{vi,vi+1}|i=1,2,...,n-1} of edges. Vehicles with capacity b are initially situated at v1. There is a job i at each vertex vi∈V, which has its own handling time hi and deadline di. With each edge {vi,vi+1}∈E, a travel time wi,i+1 is associated. Each job is processed by exactly one vehicle, and the number of jobs processed by a vehicle does not exceed the capacity b. A routing of a vehicle is called one-way if the vehicle visits every edge {vi,vi+1} exactly once (i.e., it simply moves from v1 to vn on G). Any vehicle is assumed to follow the one-way routing constraint. The problem asks to find a schedule that minimizes the number of one-way vehicles, meeting the deadline and capacity constraints. A greedy heuristic is proposed, which repeats a dynamic programming procedure for a single one-way vehicle problem of maximizing the number of non-tardy jobs. We show that the greedy heuristic runs in O(n3) time, and the approximation ratio is at most ln b+1.

Story discourse and use of mental state language between mothers and school-aged children with and without visual impairment

PubMed Central

Tadić, Valerija; Pring, Linda; Dale, Naomi

2013-01-01

Background Lack of sight compromises insight into other people’s mental states. Little is known about the role of maternal language in assisting the development of mental state language in children with visual impairment (VI). Aims To investigate mental state language strategies of mothers of school-aged children with VI and to compare these with mothers of comparable children with typically developing vision. To investigate whether the characteristics of mother–child discourse were associated with the child’s socio-communicative competence. Methods & Procedures Mother–child discourse with twelve 6–12-year-old children with VI was coded during a shared book-reading narrative and compared with 14 typically sighted children matched in age and verbal ability. Outcomes & Results Mothers of children with VI elaborated more and made significantly more references to story characters’ mental states and descriptive elaborations than mothers of sighted children. Mental state elaborations of mothers in the VI group related positively with the level produced by their children, with the association remaining after mothers’ overall verbosity and children’s developmental levels were controlled for. Frequency of maternal elaborations, including their mental state language, was related to socio-communicative competence of children with VI. Conclusions & Implications The findings offer insights into the potential contribution of maternal verbal scaffolding to mentalistic language and social–communicative competences of children with VI. PMID:24165364

36 CFR § 1210.44 - Procurement procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Procurement...

22 CFR 145.44 - Procurement procedures.

Code of Federal Regulations, 2012 CFR

2012-04-01

... metric system of measurement. (vi) Preference, to the extent practicable and economically feasible, for... EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Procurement Standards § 145...

Adsorption of Fe(II) and U(VI) to carboxyl-functionalized microspheres: The influence of speciation on uranyl reduction studied by titration and XAFS

NASA Astrophysics Data System (ADS)

Boyanov, Maxim I.; O'Loughlin, Edward J.; Roden, Eric E.; Fein, Jeremy B.; Kemner, Kenneth M.

2007-04-01

The chemical reduction of U(VI) by Fe(II) is a potentially important pathway for immobilization of uranium in subsurface environments. Although the presence of surfaces has been shown to catalyze the reaction between Fe(II) and U(VI) aqueous species, the mechanism(s) responsible for the enhanced reactivity remain ambiguous. To gain further insight into the U-Fe redox process at a complexing, non-conducting surface that is relevant to common organic phases in the environment, we studied suspensions containing combinations of 0.1 mM U(VI), 1.0 mM Fe(II), and 4.2 g/L carboxyl-functionalized polystyrene microspheres. Acid-base titrations were used to monitor protolytic reactions, and Fe K-edge and U L-edge X-ray absorption fine structure spectroscopy was used to determine the valence and atomic environment of the adsorbed Fe and U species. In the Fe + surface carboxyl system, a transition from monomeric to oligomeric Fe(II) surface species was observed between pH 7.5 and pH 8.4. In the U + surface carboxyl system, the U(VI) cation was adsorbed as a mononuclear uranyl-carboxyl complex at both pH 7.5 and 8.4. In the ternary U + Fe + surface carboxyl system, U(VI) was not reduced by the solvated or adsorbed Fe(II) at pH 7.5 over a 4-month period, whereas complete and rapid reduction to U(IV) nanoparticles occurred at pH 8.4. The U(IV) product reoxidized rapidly upon exposure to air, but it was stable over a 4-month period under anoxic conditions. Fe atoms were found in the local environment of the reduced U(IV) atoms at a distance of 3.56 Å. The U(IV)-Fe coordination is consistent with an inner-sphere electron transfer mechanism between the redox centers and involvement of Fe(II) atoms in both steps of the reduction from U(VI) to U(IV). The inability of Fe(II) to reduce U(VI) in solution and at pH 7.5 in the U + Fe + carboxyl system is explained by the formation of a transient, "dead-end" U(V)-Fe(III) complex that blocks the U(V) disproportionation pathway after the first electron transfer. The increased reactivity at pH 8.4 relative to pH 7.5 is explained by the reaction of U(VI) with an Fe(II) oligomer, whereby the bonds between Fe atoms facilitate the transfer of a second electron to the hypothetical U(V)-Fe(III) intermediate. We discuss how this mechanism may explain the commonly observed higher efficiency of uranyl reduction by adsorbed or structural Fe(II) relative to aqueous Fe(II).

Effects of Sterilization on the Physico-Chemical Properties of Natural Sediments From the Oak Ridge Reservation

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

Bank, T.L.; Kukkadapu, R.K.; Madden, A.S.

2009-04-29

Batch U(VI) sorption/reduction experiments were completed on sterilized and non-sterilized sediment samples to elucidate biological and geochemical reduction mechanisms. Results from X-ray absorption near-edge structure (XANES) spectroscopy revealed that {gamma}-sterilized sediments were actually better sorbents of U(VI), despite the absence of any measurable biological activity. These results indicate that {gamma}-irradiation induced significant physico-chemical changes in the sediment which is contrary to numerous other studies identifying {gamma}-sterilization as an effective and minimally invasive technique. To identify the extent and method of alteration of the soil as a result of {gamma}-sterilization, untreated soil samples, physically separated size fractions, and chemically extracted fractionsmore » of the soil were analyzed pre- and post-sterilization. The effects of sterilization on mineralogy, pH, natural organic matter (NOM), cation exchange capacity (CEC), and iron oxidation state were determined. Results indicated that major mineralogy of the clay and whole sediment samples was unchanged. Sediment pH decreased only slightly with {gamma}-irradiation; however, irradiation produced a significant decrease in CEC of the untreated sediments and affected both the organic and inorganic fractions. Moessbauer spectra of non-sterile and {gamma}-sterilized sediments measured more reduced iron present in {gamma}-sterilized sediments compared to non-sterile samples. Our results suggest that sterilization by {gamma}-irradiation induced iron reduction that may have increased the sorption and/or reduction of U(VI) onto these sediments. However, Moessbauer and batch sorption data are somewhat contradictory, the former indicates that the iron oxide or iron hydroxide minerals are more significantly reduced while the later indicates that reduced clay minerals account for greater sorption of U(VI).« less

Effects of gamma-sterilization on the physicochemical properties of natural sediments

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

Bank, Tracy L; Madden, Andrew; Baldwin, Mark E

2008-06-01

Batch U(VI) sorption/reduction experiments were completed on sterilized and non-sterilized sediment samples to elucidate biological and geochemical reduction mechanisms. Results from X-ray absorption near-edge structure (XANES) spectroscopy revealed that {gamma}-sterilized sediments were actually better sorbents of U(VI), despite the absence of any measurable biological activity. These results indicate that {gamma}-irradiation induced significant physico-chemical changes in the sediment which is contrary to numerous other studies identifying {gamma}-sterilization as an effective and minimally invasive technique. To identify the extent and method of alteration of the soil as a result of {gamma}-sterilization, untreated soil samples, physically separated size fractions, and chemically extracted fractionsmore » of the soil were analyzed pre- and post-sterilization. The effects of sterilization on mineralogy, pH, natural organic matter (NOM), cation exchange capacity (CEC), and iron oxidation state were determined. Results indicated that major mineralogy of the clay and whole sediment samples was unchanged. Sediment pH decreased only slightly with {gamma}-irradiation; however, irradiation produced a significant decrease in CEC of the untreated sediments and affected both the organic and inorganic fractions. Moessbauer spectra of non-sterile and {gamma}-sterilized sediments measured more reduced iron present in {gamma}-sterilized sediments compared to non-sterile samples. Our results suggest that sterilization by {gamma}-irradiation induced iron reduction that may have increased the sorption and/or reduction of U(VI) onto these sediments. However, Moessbauer and batch sorption data are somewhat contradictory, the former indicates that the iron oxide or iron hydroxide minerals are more significantly reduced while the later indicates that reduced clay minerals account for greater sorption of U(VI).« less

Functionalized paper--A readily accessible adsorbent for removal of dissolved heavy metal salts and nanoparticles from water.

PubMed

Setyono, Daisy; Valiyaveettil, Suresh

2016-01-25

Paper, a readily available renewable resource, comprises of interwoven cellulosic fibers, which can be functionalized to develop interesting low-cost adsorbent material for water purification. In this study, polyethyleneimine (PEI)-functionalized paper was used for the removal of hazardous pollutants such as Au and Ag nanoparticles, Cr(VI) anions, Ni(2+), Cd(2+), and Cu(2+) cations from spiked water samples. Compared to untreated paper, the PEI-coated paper showed significant improvement in adsorption capacities toward the pollutants investigated in this study. Kinetics, isotherm models, pH, and desorption studies were carried out to study the adsorption mechanism of pollutants on the adsorbent surface. Adsorption of pollutants was better described by pseudo-second order kinetics and Langmuir isotherm model. Maximum adsorption of anionic pollutants was achieved at pH 5 while that of cations was at pH>6. Overall, the PEI-functionalized paper showed interesting Langmuir adsorption capacities for heavy metal ions such as Cr(VI) (68 mg/g), Ni(2+) (208 mg/g), Cd(2+) (370 mg/g), and Cu(2+) (435 mg/g) ions at neutral pH. In addition, the modified paper was also used to remove Ag-citrate (79 mg/g), Ag-PVP (46 mg/g), Au-citrate (30 mg/g), Au-PVP (17 mg/g) nanoparticles from water. Desorption of NPs from the adsorbent was done by washing with 2 M HCl or thiourea solution, while heavy metal ions were desorbed using 1 M NaOH or HNO3 solution. The modified paper retained its extraction efficiencies upon desorption of pollutants. Copyright © 2015 Elsevier B.V. All rights reserved.

Two-dimensional solid-phase extraction strategy for the selective enrichment of aminoglycosides in milk.

PubMed

Shen, Aijin; Wei, Jie; Yan, Jingyu; Jin, Gaowa; Ding, Junjie; Yang, Bingcheng; Guo, Zhimou; Zhang, Feifang; Liang, Xinmiao

2017-03-01

An orthogonal two-dimensional solid-phase extraction strategy was established for the selective enrichment of three aminoglycosides including spectinomycin, streptomycin, and dihydrostreptomycin in milk. A reversed-phase liquid chromatography material (C 18 ) and a weak cation-exchange material (TGA) were integrated in a single solid-phase extraction cartridge. The feasibility of two-dimensional clean-up procedure that experienced two-step adsorption, two-step rinsing, and two-step elution was systematically investigated. Based on the orthogonality of reversed-phase and weak cation-exchange procedures, the two-dimensional solid-phase extraction strategy could minimize the interference from the hydrophobic matrix existing in traditional reversed-phase solid-phase extraction. In addition, high ionic strength in the extracts could be effectively removed before the second dimension of weak cation-exchange solid-phase extraction. Combined with liquid chromatography and tandem mass spectrometry, the optimized procedure was validated according to the European Union Commission directive 2002/657/EC. A good performance was achieved in terms of linearity, recovery, precision, decision limit, and detection capability in milk. Finally, the optimized two-dimensional clean-up procedure incorporated with liquid chromatography and tandem mass spectrometry was successfully applied to the rapid monitoring of aminoglycoside residues in milk. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

76 FR 39749 - Practice and Procedure: Rules of General Application, Safeguards, Antidumping and Countervailing...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-06

... Vol. 76 Wednesday, No. 129 July 6, 2011 Part VI International Trade Commission 19 CFR Parts 201... TRADE COMMISSION 19 CFR Parts 201, 206, 207, and 210 Practice and Procedure: Rules of General...: International Trade Commission. ACTION: Notice of proposed rulemaking. SUMMARY: The United States International...

45 CFR 74.44 - Procurement procedures.

Code of Federal Regulations, 2014 CFR

2014-10-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... FOR AWARDS AND SUBAWARDS TO INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, OTHER NONPROFIT ORGANIZATIONS...

45 CFR 2543.44 - Procurement procedures.

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2012-10-01

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24 CFR 84.44 - Procurement procedures.

Code of Federal Regulations, 2013 CFR

2013-04-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Procurement Standards § 84...

24 CFR 84.44 - Procurement procedures.

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2014-04-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Procurement Standards § 84...

45 CFR 2543.44 - Procurement procedures.

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2014-10-01

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45 CFR 74.44 - Procurement procedures.

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2011-10-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... FOR AWARDS AND SUBAWARDS TO INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, OTHER NONPROFIT ORGANIZATIONS...

20 CFR 435.44 - Procurement procedures.

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2014-04-01

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24 CFR 84.44 - Procurement procedures.

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2012-04-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Procurement Standards § 84...

10 CFR 600.144 - Procurement procedures.

Code of Federal Regulations, 2011 CFR

2011-01-01

... products and services dimensioned in the metric system of measurement. (vi) Preference, to the extent... Requirements for Grants and Cooperative Agreements With Institutions of Higher Education, Hospitals, and Other...

10 CFR 600.144 - Procurement procedures.

Code of Federal Regulations, 2013 CFR

2013-01-01

... products and services dimensioned in the metric system of measurement. (vi) Preference, to the extent... Requirements for Grants and Cooperative Agreements With Institutions of Higher Education, Hospitals, and Other...

45 CFR 2543.44 - Procurement procedures.

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2011-10-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... SERVICE GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT...

10 CFR 600.144 - Procurement procedures.

Code of Federal Regulations, 2014 CFR

2014-01-01

... products and services dimensioned in the metric system of measurement. (vi) Preference, to the extent... Requirements for Grants and Cooperative Agreements With Institutions of Higher Education, Hospitals, and Other...

20 CFR 435.44 - Procurement procedures.

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2013-04-01

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20 CFR 435.44 - Procurement procedures.

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2012-04-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, OTHER NON-PROFIT ORGANIZATIONS, AND COMMERCIAL...

45 CFR 74.44 - Procurement procedures.

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2012-10-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... FOR AWARDS AND SUBAWARDS TO INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, OTHER NONPROFIT ORGANIZATIONS...

45 CFR 2543.44 - Procurement procedures.

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2013-10-01

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20 CFR 435.44 - Procurement procedures.

Code of Federal Regulations, 2011 CFR

2011-04-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, OTHER NON-PROFIT ORGANIZATIONS, AND COMMERCIAL...

24 CFR 84.44 - Procurement procedures.

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2011-04-01

... dimensioned in the metric system of measurement. (vi) Preference, to the extent practicable and economically... EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Procurement Standards § 84...

10 CFR 600.144 - Procurement procedures.

Code of Federal Regulations, 2012 CFR

2012-01-01

... products and services dimensioned in the metric system of measurement. (vi) Preference, to the extent... Requirements for Grants and Cooperative Agreements With Institutions of Higher Education, Hospitals, and Other...

45 CFR 74.44 - Procurement procedures.

Code of Federal Regulations, 2013 CFR

2013-10-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... FOR AWARDS AND SUBAWARDS TO INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, OTHER NONPROFIT ORGANIZATIONS...

Quantum-chemistry based calibration of the alkali metal cation series (Li(+)-Cs(+)) for large-scale polarizable molecular mechanics/dynamics simulations.

PubMed

Dudev, Todor; Devereux, Mike; Meuwly, Markus; Lim, Carmay; Piquemal, Jean-Philip; Gresh, Nohad

2015-02-15

The alkali metal cations in the series Li(+)-Cs(+) act as major partners in a diversity of biological processes and in bioinorganic chemistry. In this article, we present the results of their calibration in the context of the SIBFA polarizable molecular mechanics/dynamics procedure. It relies on quantum-chemistry (QC) energy-decomposition analyses of their monoligated complexes with representative O-, N-, S-, and Se- ligands, performed with the aug-cc-pVTZ(-f) basis set at the Hartree-Fock level. Close agreement with QC is obtained for each individual contribution, even though the calibration involves only a limited set of cation-specific parameters. This agreement is preserved in tests on polyligated complexes with four and six O- ligands, water and formamide, indicating the transferability of the procedure. Preliminary extensions to density functional theory calculations are reported. © 2014 Wiley Periodicals, Inc.

Speciation of hexavalent chromium in welding fumes interference by air oxidation of chromium.

PubMed

Zatka, V J

1985-06-01

The determination of various chromium species in welding fume normally involves digestion in a hot alkaline solution. This work confirms that Cr(III) can be oxidized to Cr(VI) during this digestion. However, only dissolved forms of Cr(III), such as the hydroxochromate(III) ion, [Cr(OH)4], are susceptible to oxidation under these conditions. The air oxidation of Cr(III) can be prevented by hydrolytic destabilization of the hydroxochromate(III) complex by the presence of magnesium hydroxide precipitate. The procedure has been used successfully in the determination of insoluble chromium(VI) in welding fumes. Excellent reproducibility is documented for soluble and insoluble chromium(VI) fractions in the analysis of a bulk sample of welding fume.

15 CFR 14.44 - Procurement procedures.

Code of Federal Regulations, 2014 CFR

2014-01-01

... products and services dimensioned in the metric system of measurement. (vi) Preference, to the extent... REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, OTHER NON-PROFIT, AND...

15 CFR 14.44 - Procurement procedures.

Code of Federal Regulations, 2013 CFR

2013-01-01

... products and services dimensioned in the metric system of measurement. (vi) Preference, to the extent... REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, OTHER NON-PROFIT, AND...

49 CFR 19.44 - Procurement procedures.

Code of Federal Regulations, 2012 CFR

2012-10-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award...

22 CFR 518.44 - Procurement procedures.

Code of Federal Regulations, 2014 CFR

2014-04-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award...

49 CFR 19.44 - Procurement procedures.

Code of Federal Regulations, 2013 CFR

2013-10-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award...

22 CFR 518.44 - Procurement procedures.

Code of Federal Regulations, 2013 CFR

2013-04-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award...

15 CFR 14.44 - Procurement procedures.

Code of Federal Regulations, 2011 CFR

2011-01-01

... products and services dimensioned in the metric system of measurement. (vi) Preference, to the extent... REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, OTHER NON-PROFIT, AND...

15 CFR 14.44 - Procurement procedures.

Code of Federal Regulations, 2012 CFR

2012-01-01

... products and services dimensioned in the metric system of measurement. (vi) Preference, to the extent... REQUIREMENTS FOR GRANTS AND AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, OTHER NON-PROFIT, AND...

22 CFR 518.44 - Procurement procedures.

Code of Federal Regulations, 2011 CFR

2011-04-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award...

22 CFR 518.44 - Procurement procedures.

Code of Federal Regulations, 2012 CFR

2012-04-01

... feasible, of products and services dimensioned in the metric system of measurement. (vi) Preference, to the... AGREEMENTS WITH INSTITUTIONS OF HIGHER EDUCATION, HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award...

Application of Brazilian kaolinite clay as adsorbent to removal of U(VI) from aqueous solution: Kinetic and thermodynamic of cation-basic interactions

NASA Astrophysics Data System (ADS)

Guerra, Denis L.; Leidens, Victor L.; Viana, Rúbia R.; Airoldi, Claudio

2010-05-01

The compound N 1-[3-(trimethoxysilyl)propyl]diethylenetriamine was anchored onto Amazon kaolinite surface by heterogeneous route. The modified and natural kaolinite samples were characterized by transmission electron microscopy, scanning electron microscopic, X-ray diffraction, and nuclear magnetic nuclei of 29Si and 13C. The well-defined peaks obtained in the 13C NMR spectrum in the 5.0-62.1 ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The ability of these materials to remove U(VI) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 4.0. The kinetic parameters analyzed by the Lagergren and Elovich models gave a good fit for a pseudo-second order reaction with k2 values 16.0 and 25.1 mmol g -1 min -1 ranges for natural and modified kaolinite clays, respectively. The energetic effects caused by metal ion adsorption were determined through calorimetric titrations.

Antimicrobial, spectral, magnetic and thermal studies of Cu(II), Ni(II), Co(II), UO(2)(VI) and Fe(III) complexes of the Schiff base derived from oxalylhydrazide.

PubMed

Melha, Khlood Abou

2008-04-01

The Schiff base ligand, oxalyl [( 2 - hydroxybenzylidene) hydrazone] [corrected].H(2)L, and its Cu(II), Ni(II), Co(II), UO(2)(VI) and Fe(III) complexes were prepared and tested as antibacterial agents. The Schiff base acts as a dibasic tetra- or hexadentate ligand with metal cations in molar ratio 1:1 or 2:1 (M:L) to yield either mono- or binuclear complexes, respectively. The ligand and its metal complexes were characterized by elemental analyses, IR, (1)H NMR, Mass, and UV-Visible spectra and the magnetic moments and electrical conductance of the complexes were also determined. For binuclear complexes, the magnetic moments are quite low compared to the calculated value for two metal ions complexes and this shows antiferromagnetic interactions between the two adjacent metal ions. The ligand and its metal complexes were tested against a Gram + ve bacteria (Staphylococcus aureus), a Gram -ve bacteria (Escherichia coli), and a fungi (Candida albicans). The tested compounds exhibited high antibacterial activities.

Methods for determining soluble and insoluble Cr III and Cr VI compounds in welding fumes.

PubMed

Matczak, W; Chmielnicka, J

1989-01-01

An analytical procedure for simultaneous determination of soluble and insoluble Cr III and Cr VI compounds in welding fumes has been proposed. In the welding fume samples collected on a membrane filter, total chromium was determined with atomic absorption spectrophotometry (AAS). Glass filters with collected samples were divided into two parts. In one part of the sample, soluble and insoluble chromium was determined by means of AAS. The separation of soluble chromium III and VI was carried out on diphenylcarbazide resin. In the second part of the sample total chromium VI was determined by means of the colorimetric method with s-diphenylcarbazide. The difference in the results of these determinations allowed the calculation of the content of total Cr III, Cr III insolub. and Cr VI insolub. The results of determining chromium compounds in welding fumes samples collected in the welder's breathing zone and in experimental chambers are also presented in this paper. The content of total chromium in the fumes determined by AAS (from a membrane filtr) and that calculated from the sum of soluble and insoluble chromium (from a glass filter) were concordant and within the limits of the admissible error for the method. Total chromium content in welding fume samples collected individually was found to range from 2.4-4.2%. The percentage of particular chromium compounds as compared to total chromium (100%) amounted: total Cr III--34%, total Cr VI--66%, soluble chromium--66% and in this Cr III--20% and Cr VI--43%, insoluble chromium--34% and in this: Cr III--14% and Cr VI--20%.

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

PubMed

Panda, Jigisha; Sarkar, Priyabrata

2014-01-01

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

28 CFR 79.75 - Procedures for payment of claims.

Code of Federal Regulations, 2011 CFR

2011-07-01

... reimbursement for burial expenses; (v) Loans or loan guarantees; (vi) Education benefits and payments; (vii) Vocational rehabilitation benefits and payments; (viii) Medical, hospital, and dental benefits; or (ix...

45 CFR 80.8 - Procedure for effecting compliance.

Code of Federal Regulations, 2011 CFR

2011-10-01

... EFFECTUATION OF TITLE VI OF THE CIVIL RIGHTS ACT OF 1964 § 80.8 Procedure for effecting compliance. (a) General... appropriate. (Secs. 601, 602, Civil Rights Act of 1964, 78 Stat. 252 (42 U.S.C. 2000d, 2000d-1; sec. 182, 80... 80.8 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION NONDISCRIMINATION...

45 CFR 80.8 - Procedure for effecting compliance.

Code of Federal Regulations, 2013 CFR

2013-10-01

... EFFECTUATION OF TITLE VI OF THE CIVIL RIGHTS ACT OF 1964 § 80.8 Procedure for effecting compliance. (a) General... appropriate. (Secs. 601, 602, Civil Rights Act of 1964, 78 Stat. 252 (42 U.S.C. 2000d, 2000d-1; sec. 182, 80... 80.8 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION NONDISCRIMINATION...

45 CFR 80.8 - Procedure for effecting compliance.

Code of Federal Regulations, 2010 CFR

2010-10-01

... EFFECTUATION OF TITLE VI OF THE CIVIL RIGHTS ACT OF 1964 § 80.8 Procedure for effecting compliance. (a) General... appropriate. (Secs. 601, 602, Civil Rights Act of 1964, 78 Stat. 252 (42 U.S.C. 2000d, 2000d-1; sec. 182, 80... 80.8 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION NONDISCRIMINATION...

45 CFR 80.8 - Procedure for effecting compliance.

Code of Federal Regulations, 2012 CFR

2012-10-01

... EFFECTUATION OF TITLE VI OF THE CIVIL RIGHTS ACT OF 1964 § 80.8 Procedure for effecting compliance. (a) General... appropriate. (Secs. 601, 602, Civil Rights Act of 1964, 78 Stat. 252 (42 U.S.C. 2000d, 2000d-1; sec. 182, 80... 80.8 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION NONDISCRIMINATION...

45 CFR 80.8 - Procedure for effecting compliance.

Code of Federal Regulations, 2014 CFR

2014-10-01

... EFFECTUATION OF TITLE VI OF THE CIVIL RIGHTS ACT OF 1964 § 80.8 Procedure for effecting compliance. (a) General... appropriate. (Secs. 601, 602, Civil Rights Act of 1964, 78 Stat. 252 (42 U.S.C. 2000d, 2000d-1; sec. 182, 80... 80.8 Public Welfare Department of Health and Human Services GENERAL ADMINISTRATION NONDISCRIMINATION...

42 CFR 431.812 - Review procedures.

Code of Federal Regulations, 2013 CFR

2013-10-01

... negative case actions in the universe. (iv) Individuals whose eligibility was determined under a State's...) of this section. (vi) Provide a statistically valid error rate that can be projected to the universe...

42 CFR 431.812 - Review procedures.

Code of Federal Regulations, 2014 CFR

2014-10-01

... negative case actions in the universe. (iv) Individuals whose eligibility was determined under a State's...) of this section. (vi) Provide a statistically valid error rate that can be projected to the universe...

42 CFR 431.812 - Review procedures.

Code of Federal Regulations, 2012 CFR

2012-10-01

... negative case actions in the universe. (iv) Individuals whose eligibility was determined under a State's...) of this section. (vi) Provide a statistically valid error rate that can be projected to the universe...

Surface Area Analysis Using the Brunauer-Emmett-Teller (BET) Method: Standard Operating Procedure Series: SOP-C

DTIC Science & Technology

2016-09-01

Method Scientific Operating Procedure Series : SOP-C En vi ro nm en ta l L ab or at or y Jonathon Brame and Chris Griggs September 2016...BET) Method Scientific Operating Procedure Series : SOP-C Jonathon Brame and Chris Griggs Environmental Laboratory U.S. Army Engineer Research and...response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing

Employment discrimination: procedures for handling complaints--Equal Employment Opportunity Commission. Proposed rule.

PubMed

1981-04-17

This proposed rule sets forth procedures for the handling of complaints of employment discrimination which are filed with Federal fund granting agencies under Title VI of the Civil Rights Act of 1964, Title IX of the Education Amendments of 1972 and other provisions of Federal law which prohibit discrimination on grounds of race, color, religion, age, sex or national origin in programs or activities receiving Federal financial assistance. The regulations allow the fund granting agency to refer complaints to the Equal Employment Opportunity Commission (EEOC). For complaints covered both by Title VII of the Civil Rights Act of 1964, as amended, or other statutes within EEOC's jurisdiction and by Title VI of the Civil Rights Act or Title IX, the regulations contemplate that most complaints of individual acts of discrimination will be referred to EEOC for investigation and conciliation, while most complaints of systemic discrimination will be retained by the fund granting agency. Employment discrimination complaints which are not covered by Title VI or Title IX will be transferred to EEOC. This proposed rule is not a "major rule" as defined by Section 1(b) of Executive Order 12291.

Omeprazole decreases magnesium transport across Caco-2 monolayers

PubMed Central

Thongon, Narongrit; Krishnamra, Nateetip

2011-01-01

AIM: To elucidate the effect and underlying mechanisms of omeprazole action on Mg2+ transport across the intestinal epithelium. METHODS: Caco-2 monolayers were cultured in various dose omeprazole-containing media for 14 or 21 d before being inserted into a modified Ussing chamber apparatus to investigate the bi-directional Mg2+ transport and electrical parameters. Paracellular permeability of the monolayer was also observed by the dilution potential technique and a cation permeability study. An Arrhenius plot was performed to elucidate the activation energy of passive Mg2+ transport across the Caco-2 monolayers. RESULTS: Both apical to basolateral and basolateral to apical passive Mg2+ fluxes of omeprazole-treated epithelium were decreased in a dose- and time-dependent manner. Omeprazole also decreased the paracellular cation selectivity and changed the paracellular selective permeability profile of Caco-2 epithelium to Li+, Na+, K+, Rb+, and Cs+ from series VII to series VI of the Eisenman sequence. The Arrhenius plot revealed the higher activation energy for passive Mg2+ transport in omeprazole-treated epithelium than that of control epithelium, indicating that omeprazole affected the paracellular channel of Caco-2 epithelium in such a way that Mg2+ movement was impeded. CONCLUSION: Omeprazole decreased paracellular cation permeability and increased the activation energy for passive Mg2+ transport of Caco-2 monolayers that led to the suppression of passive Mg2+ absorption. PMID:21472124

Omeprazole decreases magnesium transport across Caco-2 monolayers.

PubMed

Thongon, Narongrit; Krishnamra, Nateetip

2011-03-28

To elucidate the effect and underlying mechanisms of omeprazole action on Mg(2+) transport across the intestinal epithelium. Caco-2 monolayers were cultured in various dose omeprazole-containing media for 14 or 21 d before being inserted into a modified Ussing chamber apparatus to investigate the bi-directional Mg(2+) transport and electrical parameters. Paracellular permeability of the monolayer was also observed by the dilution potential technique and a cation permeability study. An Arrhenius plot was performed to elucidate the activation energy of passive Mg(2+) transport across the Caco-2 monolayers. Both apical to basolateral and basolateral to apical passive Mg(2+) fluxes of omeprazole-treated epithelium were decreased in a dose- and time-dependent manner. Omeprazole also decreased the paracellular cation selectivity and changed the paracellular selective permeability profile of Caco-2 epithelium to Li(+), Na(+), K(+), Rb(+), and Cs(+) from series VII to series VI of the Eisenman sequence. The Arrhenius plot revealed the higher activation energy for passive Mg(2+) transport in omeprazole-treated epithelium than that of control epithelium, indicating that omeprazole affected the paracellular channel of Caco-2 epithelium in such a way that Mg(2+) movement was impeded. Omeprazole decreased paracellular cation permeability and increased the activation energy for passive Mg(2+) transport of Caco-2 monolayers that led to the suppression of passive Mg(2+) absorption.

42 CFR 431.812 - Review procedures.

Code of Federal Regulations, 2011 CFR

2011-10-01

... negative case actions in the universe. (iv) Individuals whose eligibility was determined under a State's... section. (vi) Provide a statistically valid error rate that can be projected to the universe that is being...

42 CFR 431.812 - Review procedures.

Code of Federal Regulations, 2010 CFR

2010-10-01

... negative case actions in the universe. (iv) Individuals whose eligibility was determined under a State's... section. (vi) Provide a statistically valid error rate that can be projected to the universe that is being...

10 CFR 63.31 - Construction authorization.

Code of Federal Regulations, 2012 CFR

2012-01-01

... subpart E of this part; (iii) DOE's quality assurance program complies with the requirements of subpart G...; and (vi) DOE's proposed operating procedures to protect health and to minimize danger to life or...

Ultratrace Determination of Cr(VI) and Pb(II) by Microsample Injection System Flame Atomic Spectroscopy in Drinking Water and Treated and Untreated Industrial Effluents

PubMed Central

Baig, Jameel Ahmed; Kazi, Tasneem Gul; Elci, Latif; Afridi, Hassan Imran; Khan, Muhammad Irfan; Naseer, Hafiz Muhammad

2013-01-01

Simple and robust analytical procedures were developed for hexavalent chromium (Cr(VI)) and lead (Pb(II)) by dispersive liquid-liquid microextraction (DLLME) using microsample injection system coupled with flame atomic absorption spectrophotometry (MIS-FAAS). For the current study, ammonium pyrrolidine dithiocarbamate (APDC), carbon tetrachloride, and ethanol were used as chelating agent, extraction solvent, and disperser solvent, respectively. The effective variables of developed method have been optimized and studied in detail. The limit of detection of Cr(VI) and Pb(II) were 0.037 and 0.054 µg/L, respectively. The enrichment factors in both cases were 400 with 40 mL of initial volumes. The relative standard deviations (RSDs, n = 6) were <4%. The applicability and the accuracy of DLLME were estimated by the analysis of Cr(VI) and Pb(II) in industrial effluent wastewater by standard addition method (recoveries >96%). The proposed method was successfully applied to the determination of Cr(VI) and Pb(II) at ultratrace levels in natural drinking water and industrial effluents wastewater of Denizli. Moreover, the proposed method was compared with the literature reported method. PMID:24163779

The influence of extraction procedure on ion concentrations in sediment pore water

USGS Publications Warehouse

Winger, P.V.; Lasier, P.J.; Jackson, B.P.

1998-01-01

Sediment pore water has the potential to yield important information on sediment quality, but the influence of isolation procedures on the chemistry and toxicity are not completely known and consensus on methods used for the isolation from sediment has not been reached. To provide additional insight into the influence of collection procedures on pore water chemistry, anion (filtered only) and cation concentrations were measured in filtered and unfiltered pore water isolated from four sediments using three different procedures: dialysis, centrifugation and vacuum. Peepers were constructed using 24-cell culture plates and cellulose membranes, and vacuum extractors consisted of fused-glass air stones attached with airline tubing to 60cc syringes. Centrifugation was accomplished at two speeds (2,500 and 10,000 x g) for 30 min in a refrigerated centrifuge maintained at 4?C. Only minor differences in chemical characteristics and cation and anion concentrations were found among the different collecting methods with differences being sediment specific. Filtering of the pore water did not appreciably reduce major cation concentrations, but trace metals (Cu and Pb) were markedly reduced. Although the extraction methods evaluated produced pore waters of similar chemistries, the vacuum extractor provided the following advantages over the other methods: (1) ease of extraction, (2) volumes of pore water isolated, (3) minimal preparation time and (4) least time required for extraction of pore water from multiple samples at one time.

Kinetics of triscarbonato uranyl reduction by aqueous ferrous iron: a theoretical study.

PubMed

Wander, Matthew C F; Kerisit, Sebastien; Rosso, Kevin M; Schoonen, Martin A A

2006-08-10

Uranium is a pollutant whose mobility is strongly dependent on its oxidation state. While U(VI) in the form of the uranyl cation is readily reduced by a range of natural reductants, by contrast complexation of uranyl by carbonate greatly reduces its reduction potential and imposes increased electron transfer (ET) distances. Very little is known about the elementary processes involved in uranium reduction from U(VI) to U(V) to U(IV) in general. In this study, we examine the theoretical kinetics of ET from ferrous iron to triscarbonato uranyl in aqueous solution. A combination of molecular dynamics (MD) simulations and density functional theory (DFT) electronic structure calculations is employed to compute the parameters that enter into Marcus' ET model, including the thermodynamic driving forces, reorganization energies, and electronic coupling matrix elements. MD simulations predict that two ferrous iron atoms will bind in an inner-sphere fashion to the three-membered carbonate ring of triscarbonato uranyl, forming the charge-neutral ternary Fe(2)UO(2)(CO(3))(3)(H(2)O)(8) complex. Through a sequential proton-coupled electron-transfer mechanism (PCET), the first ET step converting U(VI) to U(V) is predicted by DFT to occur with an electronic barrier that corresponds to a rate on the order of approximately 1 s(-1). The second ET step converting U(V) to U(IV) is predicted to be significantly endergonic. Therefore, U(V) is a stabilized end product in this ET system, in agreement with experiment.

Fast and efficient mesoporous adsorbents for the separation of toxic compounds from aqueous media.

PubMed

Anbia, Mansoor; Mohammadi, Nourali; Mohammadi, Kaveh

2010-04-15

The effect of cationic template on the adsorption of chromium (VI), furfural and copperphthalocyanine-3,4',4'',4'''-tetrasulfonic acid tetrasodium salt (CuPc) in MCM-41 and MCM-48 mesoporous materials was investigated in this work. We used cetyltrimethylammonium bromide (CTAB) as the cationic template and sodiummetasilicate (for MCM-41) and tetraethyl-orthosilicon (for MCM-48) as the silica source for the synthesis of mesoporous materials. The properties of synthesized samples were characterized with XRD-low angle, SEM, N(2) adsorption-desorption and TG-DT analysis. The extent of adsorption was investigated as a function of solution pH, shaking speed, contact time, analyte concentration, reaction temperature and supporting electrolyte (sodium chloride) concentration. Langmuir and Freundlich isotherms were used to model the adsorption equilibrium data. The as-synthesized mesoporous samples showed very high adsorption capacity for the analytes and adsorption uptakes were rapid on the adsorbents reaching equilibrium in less than 2 h. The materials without surfactant did not show significant affinity for the analytes. 2009 Elsevier B.V. All rights reserved.

43 CFR 4.823 - Interlocutory appeals.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the Interior-Effectuation of Title VI of the Civil Rights Act of 1964 Procedures § 4.823 Interlocutory..., and the administrative law judge has certified the interlocutory ruling on the record or abused his...

7 CFR 1.140 - Conferences and procedure.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) An outline of the case or defense; (ii) The legal theories upon which the party will rely; (iii... other witnesses; (v) Negotiation, compromise, or settlement of issues; (vi) The exchange of copies of...

7 CFR 1.140 - Conferences and procedure.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) An outline of the case or defense; (ii) The legal theories upon which the party will rely; (iii... other witnesses; (v) Negotiation, compromise, or settlement of issues; (vi) The exchange of copies of...

7 CFR 1.140 - Conferences and procedure.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) An outline of the case or defense; (ii) The legal theories upon which the party will rely; (iii... other witnesses; (v) Negotiation, compromise, or settlement of issues; (vi) The exchange of copies of...

7 CFR 1.140 - Conferences and procedure.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) An outline of the case or defense; (ii) The legal theories upon which the party will rely; (iii... other witnesses; (v) Negotiation, compromise, or settlement of issues; (vi) The exchange of copies of...

Detection of Damage in Hydraulic Components by Acoustic Emission Techniques.

DTIC Science & Technology

1984-04-01

49 ".-4.- Vane Pumps 50 Piston Pumps 61 Gear Pumps 66 VI FIELD TESTS (GEAR PUMPS) 108 Pump Cavitation 108 Internal Mechanical Damage Test Procedure...with Bad Bearing 60 5.6 a Frequency Spectrum (0-100 KHz) of Piston Pump. Cavitation Test, Inlet Pressure =1.55 atm (Normal) 63 5.6 b Frequency Spectrum...0-100 KHz) of Piston Pump. Cavitation Test, Inlet Pressure =1.38 atm (Incipient) 64. vi i . .e 0" S.. j~ * .’ *"-.i’.-..N.?.. .. ° .,LIST OF FIGURES

Fate and transport of uranium (VI) in weathered saprolite

DOE PAGES

Kim, Young-Jin; Brooks, Scott C.; Zhang, Fan; ...

2014-11-09

We conducted batch and column experiments to investigate sorption and transport of uranium (U) in the presence of saprolite derived from interbedded shale, limestone, and sandstone sequences. Sorption kinetics were measured at two initial concentrations (C0; 1, 10 mM) and three soil:solution ratios (Rs/w; 0.005, 0.25, 2 kg/L) at pH 4.5 (pH of the saprolite). The rate of U loss from solution (mmole/L/h) increased with increasing Rs/w. Uranium sorption exhibited a fast phase with 80% sorption in the first eight hours for all C0 and Rs/w values and a slow phase during which the reaction slowly approached (pseudo) equilibrium overmore » the next seven days. The pH-dependency of U sorption was apparent in pH sorption edges. U(VI) sorption increased over the pH range 4e6, then decreased sharply at pH > 7.5. U(VI) sorption edges were well described by a surface complexation model using calibrated parameters and the reaction network proposed by Waite et al. (1994). Sorption isotherms measured using the same Rs/w and pH values showed a solids concentration effect where U(VI) sorption capacity and affinity decreased with increasing solids concentration. Moreover, this effect may have been due to either particle aggregation or competition between U(VI) and exchangeable cations for sorption sites. The surface complexation model with calibrated parameters was able to predict the general sorption behavior relatively well, but failed to reproduce solid concentration effects, implying the importance of appropriate design if batch experiments are to be utilized for dynamic systems. Transport of U(VI) through the packed column was significantly retarded. We also conducted transport simulations using the reactive transport model HydroGeoChem (HGC) v5.0 that incorporated the surface complexation reaction network used to model the batch data. Model parameters reported by Waite et al. (1994) provided a better prediction of U transport than optimized parameters derived from our sorption edges. The results presented in this study highlight the challenges in defining appropriate conditions for batch-type experiments used to extrapolate parameters for transport models, and also underline a gap in our ability to transfer batch results to transport simulations.« less

Reduction-Triggered Self-Assembly of Nanoscale Molybdenum Oxide Molecular Clusters

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

Yin, Panchao; Wu, Bin; Li, Tao

A 2.9 nm molybdenum oxide cluster {Mo 132} (Formula: [Mo VI 72Mo V 60O 372(CH 3COO) 30(H 2O) 72] 42-) can be obtained by reducing ammonium molybdate with hydrazine sulfate in weakly acidic CH 3COOH/CH 3COO- buffers. This reaction has been monitored by time-resolved UV-Vis, 1H-NMR, small angle X-ray/neutron scattering, and X-ray absorption near edge structure spectroscopy. The growth of {Mo 132} cluster shows a typical sigmoid curve, suggesting a multi-step assembly mechanism for this reaction. The reaction starts with a lag phase period when partial MoVI centers of molybdate precursors are reduced to form {MoV2(acetate)} structures under the coordinationmore » effect of the acetate groups. Once the concentration of {Mo V 2(acetate)} reaches a critical value, it triggers the assembly of Mo V and Mo VI species into {Mo 132} clusters. Parameters such as the type and amount of reducing agent, the pH, the type of cation, and the type of organic ligand in the reaction buffer, have been studied for the roles they play in the formation of the target clusters.Understanding the formation mechanism of giant molecular clusters is essential for rational design and synthesis of cluster-based nanomaterials with required morphologies and functionalities. Here, typical synthetic reactions of a 2.9 nm spherical molybdenum oxide cluster, {Mo 132} (formula: [Mo VI 72Mo V 60O 372(CH 3COO) 30(H 2O) 72] 42), with systematically varied reaction parameters have been fully explored to determine the morphologies and concentration of products, reduction of metal centers, and chemical environments of the organic ligands. The growth of these clusters shows a typical sigmoid curve, suggesting a general multistep self-assembly mechanism for the formation of giant molecular clusters. The reaction starts with a lag phase period when partial MoVI centers of molybdate precursors are reduced to form {Mo V 2(acetate)} structures under the coordination effect of the acetate groups. Once the concentration of {MoV2(acetate)} reaches a critical value, it triggers the co-assembly of Mo V and Mo VI species into the giant clusters.« less

Reduction-Triggered Self-Assembly of Nanoscale Molybdenum Oxide Molecular Clusters

DOE PAGES

Yin, Panchao; Wu, Bin; Li, Tao; ...

2016-07-26

A 2.9 nm molybdenum oxide cluster {Mo 132} (Formula: [Mo VI 72Mo V 60O 372(CH 3COO) 30(H 2O) 72] 42-) can be obtained by reducing ammonium molybdate with hydrazine sulfate in weakly acidic CH 3COOH/CH 3COO- buffers. This reaction has been monitored by time-resolved UV-Vis, 1H-NMR, small angle X-ray/neutron scattering, and X-ray absorption near edge structure spectroscopy. The growth of {Mo 132} cluster shows a typical sigmoid curve, suggesting a multi-step assembly mechanism for this reaction. The reaction starts with a lag phase period when partial MoVI centers of molybdate precursors are reduced to form {MoV2(acetate)} structures under the coordinationmore » effect of the acetate groups. Once the concentration of {Mo V 2(acetate)} reaches a critical value, it triggers the assembly of Mo V and Mo VI species into {Mo 132} clusters. Parameters such as the type and amount of reducing agent, the pH, the type of cation, and the type of organic ligand in the reaction buffer, have been studied for the roles they play in the formation of the target clusters.Understanding the formation mechanism of giant molecular clusters is essential for rational design and synthesis of cluster-based nanomaterials with required morphologies and functionalities. Here, typical synthetic reactions of a 2.9 nm spherical molybdenum oxide cluster, {Mo 132} (formula: [Mo VI 72Mo V 60O 372(CH 3COO) 30(H 2O) 72] 42), with systematically varied reaction parameters have been fully explored to determine the morphologies and concentration of products, reduction of metal centers, and chemical environments of the organic ligands. The growth of these clusters shows a typical sigmoid curve, suggesting a general multistep self-assembly mechanism for the formation of giant molecular clusters. The reaction starts with a lag phase period when partial MoVI centers of molybdate precursors are reduced to form {Mo V 2(acetate)} structures under the coordination effect of the acetate groups. Once the concentration of {MoV2(acetate)} reaches a critical value, it triggers the co-assembly of Mo V and Mo VI species into the giant clusters.« less

Valve in valve transcatheter aortic valve implantation (ViV-TAVI) versus redo-Surgical aortic valve replacement (redo-SAVR): A systematic review and meta-analysis.

PubMed

Nalluri, Nikhil; Atti, Varunsiri; Munir, Abdullah B; Karam, Boutros; Patel, Nileshkumar J; Kumar, Varun; Vemula, Praveen; Edla, Sushruth; Asti, Deepak; Paturu, Amrutha; Gayam, Sriramya; Spagnola, Jonathan; Barsoum, Emad; Maniatis, Gregory A; Tamburrino, Frank; Kandov, Ruben; Lafferty, James; Kliger, Chad

2018-05-20

Bioprosthetic (BP) valves have been increasingly used for aortic valve replacement over the last decade. Due to their limited durability, patients presenting with failed BP valves are rising. Valve in Valve - Transcatheter Aortic Valve Implantation (ViV-TAVI) emerged as an alternative to the gold standard redo-Surgical Aortic Valve Replacement (redo-SAVR). However, the utility of ViV-TAVI is poorly understood. A systematic electronic search of the scientific literature was done in PubMed, EMBASE, SCOPUS, Google Scholar, and ClinicalTrials.gov. Only studies which compared the safety and efficacy of ViV-TAVI and redo-SAVR head to head in failed BP valves were included. Six observational studies were eligible and included 594 patients, of whom 255 underwent ViV- TAVI and 339 underwent redo-SAVR. There was no significant difference between ViV-TAVI and redo- SAVR for procedural, 30 day and 1 year mortality rates. ViV-TAVI was associated with lower risk of permanent pacemaker implantation (PPI) (OR: 0.43, CI: 0.21-0.89; P = 0.02) and a trend toward increased risk of paravalvular leak (PVL) (OR: 5.45, CI: 0.94-31.58; P = 0.06). There was no significant difference for stroke, major bleeding, vascular complications and postprocedural aortic valvular gradients more than 20 mm-hg. Our results reiterate the safety and feasibility of ViV-TAVI for failed aortic BP valves in patients deemed to be at high risk for surgery. VIV-TAVI was associated with lower risk of permanent pacemaker implantation with a trend toward increased risk of paravalvular leak. © 2018, Wiley Periodicals, Inc.

New procedure for multielemental speciation analysis of five toxic species: As(III), As(V), Cr(VI), Sb(III) and Sb(V) in drinking water samples by advanced hyphenated technique HPLC/ICP-DRC-MS.

PubMed

Marcinkowska, Monika; Komorowicz, Izabela; Barałkiewicz, Danuta

2016-05-12

Analytical procedure dedicated for multielemental determination of toxic species: As(III), As(V), Cr(VI), Sb(III) and Sb(V) in drinking water samples using high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC/ICP-DRC-MS) technique was developed. Optimization of the detection and separation conditions was conducted. Dynamic reaction cell (DRC) with oxygen as a reaction gas was involved in the experiments. Obtained analytical signals for species separation were symmetrical, as studied by anion-exchange chromatography. Applied mobile phase consisted of 3 mM of EDTANa2 and 36 mM of ammonium nitrate. Full separation of species in the form of the following forms: H3AsO3, H2AsO4(-), SbO2(-), Sb(OH)6(-), CrO4(2-) was achieved in 15 min with use of gradient elution program. Detailed validation of analytical procedure proved the reliability of analytical measurements. The procedure was characterized by high precision in the range from 1.7% to 2.4%. Detection limits (LD) were 0.067 μg L(-1), 0.068 μg L(-1), 0.098 μg L(-1), 0.083 μg L(-1) and 0.038 μg L(-1) for As(III), As(V), Cr(VI), Sb(III) and Sb(V), respectively. Obtained recoveries confirmed the lack of interferences' influence on analytical signals as their values were in the range of 91%-110%. The applicability of the proposed procedure was tested on drinking water samples characterized by mineralization up to 650 mg L(-1). Copyright © 2016 Elsevier B.V. All rights reserved.

7 CFR 1.421 - Prehearing conferences and procedures.

Code of Federal Regulations, 2013 CFR

2013-01-01

...; (iii) The legal theories upon which the party will rely; (iv) Copies of or a list of documents which...; (v) The exchange of copies of proposed exhibits; (vi) The identification of documents or matters of...

7 CFR 1.421 - Prehearing conferences and procedures.

Code of Federal Regulations, 2012 CFR

2012-01-01

...; (iii) The legal theories upon which the party will rely; (iv) Copies of or a list of documents which...; (v) The exchange of copies of proposed exhibits; (vi) The identification of documents or matters of...

7 CFR 1.421 - Prehearing conferences and procedures.

Code of Federal Regulations, 2014 CFR

2014-01-01

...; (iii) The legal theories upon which the party will rely; (iv) Copies of or a list of documents which...; (v) The exchange of copies of proposed exhibits; (vi) The identification of documents or matters of...

7 CFR 1.421 - Prehearing conferences and procedures.

Code of Federal Regulations, 2011 CFR

2011-01-01

...; (iii) The legal theories upon which the party will rely; (iv) Copies of or a list of documents which...; (v) The exchange of copies of proposed exhibits; (vi) The identification of documents or matters of...

15 CFR 400.27 - Procedure for processing application.

Code of Federal Regulations, 2010 CFR

2010-01-01

... exports and imports, and the net effect on U.S. employment; (vi) Conducting appropriate industry surveys... situation under paragraph (d)(2)(v)(A) of this section shall be completed and submitted to the Executive...

Quantifying Nanoparticle Release from Nanotechnology: Scientific Operating Procedure Series: SOP C 3

DTIC Science & Technology

2017-02-01

Operating Procedure Series : SOP-C-3 En vi ro nm en ta l L ab or at or y David P. Martin, Aimee R. Poda, and Anthony J. Bednar February 2017...Operating Procedure Series : SOP-C-3 David P. Martin, Aimee R. Poda, and Anthony J. Bednar Environmental Laboratory U.S. Army Engineer Research and...so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. ERDC/EL SR-17-1 iii

16 CFR 4.9 - The public record.

Code of Federal Regulations, 2012 CFR

2012-01-01

... opinions, orders, statements of policy and interpretations, administrative staff manuals, general... policies and interpretations, its nonadjudicative procedures, its rules of practice for adjudicative... connection with proceedings before other federal agencies or state or local government bodies; (vi...

16 CFR 4.9 - The public record.

Code of Federal Regulations, 2013 CFR

2013-01-01

... opinions, orders, statements of policy and interpretations, administrative staff manuals, general... policies and interpretations, its nonadjudicative procedures, its rules of practice for adjudicative... connection with proceedings before other federal agencies or state or local government bodies; (vi...

16 CFR 4.9 - The public record.

Code of Federal Regulations, 2011 CFR

2011-01-01

... opinions, orders, statements of policy and interpretations, administrative staff manuals, general... policies and interpretations, its nonadjudicative procedures, its rules of practice for adjudicative... connection with proceedings before other federal agencies or state or local government bodies; (vi...

VizieR Online Data Catalog: USNO Photographic Parallaxes. I. (Monet+, 1992)

NASA Astrophysics Data System (ADS)

Monet, D. G.; Dahn, C. C.; Vrba, F. J.; Harris, H. C.; Pier, J. R.; Luginbuhl, C. B.; Ables, H. D.

2000-11-01

The U.S. Naval Observatory CCD trigonometric parallax program is described in detail, including the instrumentation employed, observing procedures followed, and reduction procedures applied. Astrometric results are presented for 72 stars ranging in apparent brightness from V=15.16 to 19.58. Photometry (V and V-I on the Kron-Cousins system) is presented for the parallax stars and for all 426 individual reference stars employed in the astrometric solutions. Corrections for differential color refraction, calibrated to the observed V-I colors, have been applied to all astrometric measures. The mean errors in the relative parallaxes range from ±0.0005" to ±0.0027" with a median value of ±0.0010". Seventeen of the 23 stars with Vtan>200km/s form a well-delineated sequence of extreme subdwarfs covering 11.5

A Cr(VI) selective probe based on a quinoline-amide calix[4]arene

NASA Astrophysics Data System (ADS)

Ferreira, Juliane F.; Bagatin, Izilda A.

2018-01-01

A new quinoline-amide calix[4]arene 3-receptor for detection of hazardous anions and cations have been synthesized. The 3-receptor was examined for its sensing properties towards several different anions (Cr2O72 -, SCN-, F-, Cl-, NO3-) and metal ions (Hg2+, Cd2+, Ag+) by UV-vis and fluorescence spectroscopies. It was detected that the 3-receptor has only sensing ability for Cr2O72 - and Hg2+ ions, resulting in the association constants higher for Cr2O72 - than to the Hg2+ ions. High selectivity towards Cr2O72 - were also observed by fluorescence measurement among other ions (F-, Cl-, SCN-, Hg2+, Cd2+, Ag+) with a low limit of detection (7.36 × 10-6 mol dm-3). Proton NMR anion-binding investigations revealed a strong interaction of Cr2O72 - anion with NH and CH groups of the receptor, showing that the combination with hydrogen-bonds donor groups strengthened the anion receptor association. Furthermore, remarkable association constants for dichromate anion obtained by all techniques strongly suggest the 3-receptor as a selective Cr(VI) sensor.

A Cr(VI) selective probe based on a quinoline-amide calix[4]arene.

PubMed

Ferreira, Juliane F; Bagatin, Izilda A

2018-01-15

A new quinoline-amide calix[4]arene 3-receptor for detection of hazardous anions and cations have been synthesized. The 3-receptor was examined for its sensing properties towards several different anions (Cr 2 O 7 2- , SCN - , F - , Cl - , NO 3 - ) and metal ions (Hg 2+ , Cd 2+ , Ag + ) by UV-vis and fluorescence spectroscopies. It was detected that the 3-receptor has only sensing ability for Cr 2 O 7 2- and Hg 2+ ions, resulting in the association constants higher for Cr 2 O 7 2- than to the Hg 2+ ions. High selectivity towards Cr 2 O 7 2- were also observed by fluorescence measurement among other ions (F - , Cl - , SCN - , Hg 2+ , Cd 2+ , Ag + ) with a low limit of detection (7.36×10 -6 moldm -3 ). Proton NMR anion-binding investigations revealed a strong interaction of Cr 2 O 7 2- anion with NH and CH groups of the receptor, showing that the combination with hydrogen-bonds donor groups strengthened the anion receptor association. Furthermore, remarkable association constants for dichromate anion obtained by all techniques strongly suggest the 3-receptor as a selective Cr(VI) sensor. Copyright © 2017 Elsevier B.V. All rights reserved.

Thermal expansion of the nuclear fuel-sodium reaction product Na3(U0.84(2),Na0.16(2))O4 - Structural mechanism and comparison with related sodium-metal ternary oxides

NASA Astrophysics Data System (ADS)

Illy, Marie-Claire; Smith, Anna L.; Wallez, Gilles; Raison, Philippe E.; Caciuffo, Roberto; Konings, Rudy J. M.

2017-07-01

Na3.16(2)UV,VI0.84(2)O4 is obtained from the reaction of sodium with uranium dioxide under oxygen potential conditions typical of a sodium-cooled fast nuclear reactor. In the event of a breach of the steel cladding, it would be the dominant reaction product forming at the rim of the mixed (U,Pu)O2 fuel pellets. High-temperature X-ray diffraction measurements show that a distortion of the uranium environment in Na3.16(2)UV,VI0.84(2)O4 results in a strongly anisotropic thermal expansion. A comparison with several related sodium metallates Nan-2Mn+On-1 - including Na3SbO4 and Na3TaO4, whose crystal structures are reported for the first time - has allowed us to assess the role played in the lattice expansion by the Mn+ cation radius and the Na/M ratio. On this basis, the thermomechanical behavior of the title compound is discussed, along with those of several related double oxides of sodium and actinide elements, surrogate elements, or fission products.

Estimating lake susceptibility to acidification due to acid deposition.

Treesearch

Dale S. Nichols

1990-01-01

Presents a graphical procedure for evaluating the same sensitivity of lakes to acidification due to acid deposition. The procedure is based on empirical relationships between sulfur (and in some cases nitrogen) deposition rates and lake pH, acid-neutralizing capacity, base cation concentrations, and the amount of runoff.

Exploration of a Variety of Copper Molybdate Coordination Hybrids Based on a Flexible Bis(1,2,4-triazole) Ligand: A Look through the Composition-Space Diagram.

PubMed

Senchyk, Ganna A; Lysenko, Andrey B; Domasevitch, Konstantin V; Erhart, Oliver; Henfling, Stefan; Krautscheid, Harald; Rusanov, Eduard B; Krämer, Karl W; Decurtins, Silvio; Liu, Shi-Xia

2017-11-06

We investigated the coordination ability of the bis(1,2,4-triazolyl) module, tr 2 pr = 1,3-bis(1,2,4-triazol-4-yl)propane, toward the engineering of solid-state structures of copper polyoxomolybdates utilizing a composition space diagram approach. Different binding modes of the ligand including [N-N]-bridging and N-terminal coordination and the existence of favorable conformation forms (anti/anti, gauche/anti, and gauche/gauche) resulted in varieties of mixed metal Cu I /Mo VI and Cu II /Mo VI coordination polymers prepared under hydrothermal conditions. The composition space analysis employed was aimed at both the development of new coordination solids and their crystallization fields through systematic changes of the reagent ratios [copper(II) and molybdenum(VI) oxide precursors and the tr 2 pr ligand]. Nine coordination compounds were synthesized and structurally characterized. The diverse coordination architectures of the compounds are composed of cationic fragments such as [Cu II 3 (μ 2 -OH) 2 (μ 2 -tr) 2 ] 4+ , [Cu II 3 (μ 2 -tr) 6 ] 6+ , [Cu II 2 (μ 2 -tr) 3 ] 4+ , etc., connected to polymeric arrays by anionic species (molybdate MoO 4 2- , isomeric α-, δ-, and β-octamolybdates {Mo 8 O 26 } 4- or {Mo 8 O 28 H 2 } 6- ). The inorganic copper(I,II)/molybdenum(VI) oxide matrix itself forms discrete or low-dimensional subtopological motifs (0D, 1D, or 2D), while the organic spacers interconnect them into higher-dimensional networks. The 3D coordination hybrids show moderate thermal stability up to 230-250 °C, while for the 2D compounds, the stability of the framework is distinctly lower (∼190 °C). The magnetic properties of the most representative samples were investigated. The magnetic interactions were rationalized in terms of analyzing the planes of the magnetic orbitals.

Characterizing particle-scale equilibrium adsorption and kinetics of uranium(VI) desorption from U-contaminated sediments

USGS Publications Warehouse

Stoliker, Deborah L.; Liu, Chongxuan; Kent, Douglas B.; Zachara, John M.

2013-01-01

Rates of U(VI) release from individual dry-sieved size fractions of a field-aggregated, field-contaminated composite sediment from the seasonally saturated lower vadose zone of the Hanford 300-Area were examined in flow-through reactors to maintain quasi-constant chemical conditions. The principal source of variability in equilibrium U(VI) adsorption properties of the various size fractions was the impact of variable chemistry on adsorption. This source of variability was represented using surface complexation models (SCMs) with different stoichiometric coefficients with respect to hydrogen ion and carbonate concentrations for the different size fractions. A reactive transport model incorporating equilibrium expressions for cation exchange and calcite dissolution, along with rate expressions for aerobic respiration and silica dissolution, described the temporal evolution of solute concentrations observed during the flow-through reactor experiments. Kinetic U(VI) desorption was well described using a multirate SCM with an assumed lognormal distribution for the mass-transfer rate coefficients. The estimated mean and standard deviation of the rate coefficients were the same for all <2 mm size fractions but differed for the 2–8 mm size fraction. Micropore volumes, assessed using t-plots to analyze N2 desorption data, were also the same for all dry-sieved <2 mm size fractions, indicating a link between micropore volumes and mass-transfer rate properties. Pore volumes for dry-sieved size fractions exceeded values for the corresponding wet-sieved fractions. We hypothesize that repeated field wetting and drying cycles lead to the formation of aggregates and/or coatings containing (micro)pore networks which provided an additional mass-transfer resistance over that associated with individual particles. The 2–8 mm fraction exhibited a larger average and standard deviation in the distribution of mass-transfer rate coefficients, possibly caused by the abundance of microporous basaltic rock fragments.

Rasch validation of the PHQ-9 in people with visual impairment in South India.

PubMed

Gothwal, Vijaya K; Bagga, Deepak K; Sumalini, Rebecca

2014-01-01

The Patient-Health Questionnaire (PHQ-9) is a widely used screening instrument for depression. Recently, its properties as a measure were investigated using Rasch analysis in an Australian population with visual impairment (VI) and it was demonstrated to possess excellent measurement properties, but the response scale required shortening (modified PHQ-9). However, further validation was recommended to substantiate its use with the growing population of VI. Therefore, we aimed to use Rasch analysis to evaluate the measurement properties of the modified PHQ-9 in an Indian population with VI. 303 patients with VI (mean age 40.2 years; 71% male) referred to Vision Rehabilitation Centres were administered the PHQ-9 by trained interviewer. Rasch analysis was used to investigate the psychometric properties of the modified PHQ-9. Rasch analysis showed good fit to the model, no misfitting items and an acceptable person separation reliability (0.82). Dimensionality testing supported combining 9 items to create a total score. Targeting was sub-optimal (-1.30 logits); more difficult items are needed. One item ('trouble falling asleep') showed notable differential item functioning, DIF (1.18 logits) by duration of VI. The generalisability of these results might be restricted to patients with VI presenting to a tertiary eye care centre. Except for DIF, the performance of the modified PHQ-9 is consistent with that of the original, albeit in a different cultural context (Indian population with VI). Clinicians/researchers can readily use the modified PHQ-9 without formal training in Rasch procedures given the provision of ready-to-use spreadsheets that convert raw to Rasch-scaled scores. However the conversions will apply only if the sample being tested is similar to that of the present study. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous determination of Cr(iii) and Cr(vi) using reversed-phased ion-pairing liquid chromatography with dynamic reaction cell inductively coupled plasma mass spectrometry

USGS Publications Warehouse

Wolf, R.E.; Morrison, J.M.; Goldhaber, M.B.

2007-01-01

A method for the simultaneous determination of Cr(iii) and Cr(vi) species in waters, soil leachates and synthetic bio-fluids is described. The method uses reversed-phase ion-pairing liquid chromatography to separate the chromium species and a dynamic reaction cell (DRC??) equipped ICP-MS for detection of chromium. Separation of the chromium species is carried out in less than 2 min. Cr(iii) is complexed with ethylenediaminetetraacetic acid (EDTA) prior to separation by mixing samples with the mobile phase containing 2.0 mM tetrabutylammonium hydroxide (TBAOH), 0.5 mM EDTA (dipotassium salt), and 5% (vol/vol) methanol, adjusted to pH 7.6. The interfering 40Ar 12C+ background peak at mass 52 was reduced by over four orders of magnitude to less than 200 cps by using 0.65 mL min-1 ammonia as a reaction gas and an RPq setting on the DRC of 0.75. Method detection limits (MDLs) of 0.09 ??g L-1 for Cr(iii) and 0.06 ??g L-1 for Cr(vi) were obtained based on peak areas at mass 52 for 50 ??L injections of low level spikes. Reproducibility at 2 ??g L-1 was 3% RSD for 5 replicate injections. The tolerance of the method to various levels of common cations and anions found in natural waters and to matrix constituents found in soil leachates and simulated gastric and lung fluids was tested by performing spike recovery calculations for a variety of samples. ?? The Royal Society of Chemistry.

Speciation Methods Used to Assess Potential Health Effects of Toxic Metals in Environmental Materials

USGS Publications Warehouse

Wolf, Ruth E.; Morman, Suzette A.; Plumlee, Geoffrey S.

2008-01-01

Assessing potential exposures to toxic metals or metalloids such as arsenic and chromium in environmental materials is important in protecting public health. The chemical form of an element in, or released from, a material is also important, since some forms, such as Cr(VI), are more toxic than others, for example, Cr(III). We have used a variety of procedures to assess potential exposures to hexavalent chromium in ash and burned soils from October 2007 southern California wildfires. Synthetic lung-fluid and de-ionized water extractions simulate release in the lungs and potential environmental releases due to rainfall. Extracts were analyzed for specific chromium and arsenic species using HPLC-ICP-MS methodology. Results indicate that the highly oxidizing environment in wildfires promotes some chromium conversion to Cr(VI), and that the caustic alkalinity of ash enhances Cr(VI) release and stability in lung fluids and rainfall.

Fundamental Chemical Kinetic And Thermodynamic Data For Purex Process Models

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

Taylor, R.J.; Fox, O.D.; Sarsfield, M.J.

2007-07-01

To support either the continued operations of current reprocessing plants or the development of future fuel processing using hydrometallurgical processes, such as Advanced Purex or UREX type flowsheets, the accurate simulation of Purex solvent extraction is required. In recent years we have developed advanced process modeling capabilities that utilize modern software platforms such as Aspen Custom Modeler and can be run in steady state and dynamic simulations. However, such advanced models of the Purex process require a wide range of fundamental data including all relevant basic chemical kinetic and thermodynamic data for the major species present in the process. Thismore » paper will summarize some of these recent process chemistry studies that underpin our simulation, design and testing of Purex solvent extraction flowsheets. Whilst much kinetic data for actinide redox reactions in nitric acid exists in the literature, the data on reactions in the diluted TBP solvent phase is much rarer. This inhibits the accurate modelization of the Purex process particularly when species show a significant extractability in to the solvent phase or when cycling between solvent and aqueous phases occurs, for example in the reductive stripping of Pu(IV) by ferrous sulfamate in the Magnox reprocessing plant. To support current oxide reprocessing, we have investigated a range of solvent phase reactions: - U(IV)+HNO{sub 3}; - U(IV)+HNO{sub 2}; - U(IV)+HNO{sub 3} (Pu catalysis); - U(IV)+HNO{sub 3} (Tc catalysis); - U(IV)+ Np(VI); - U(IV)+Np(V); - Np(IV)+HNO{sub 3}; - Np(V)+Np(V); Rate equations have been determined for all these reactions and kinetic rate constants and activation energies are now available. Specific features of these reactions in the TBP phase include the roles of water and hydrolyzed intermediates in the reaction mechanisms. In reactions involving Np(V), cation-cation complex formation, which is much more favourable in TBP than in HNO{sub 3}, also occurs and complicates the redox chemistry. Whilst some features of the redox chemistry in TBP appear similar to the corresponding reactions in aqueous HNO{sub 3}, there are notable differences in rates, the forms of the rate equations and mechanisms. Secondly, to underpin the development of advanced single cycle flowsheets using the complexant aceto-hydroxamic acid, we have also characterised in some detail its redox chemistry and solvent extraction behaviour with both Np and Pu ions. We find that simple hydroxamic acids are remarkably rapid reducing agents for Np(VI). They also reduce Pu(VI) and cause a much slower reduction of Pu(IV) through a complex mechanism involving acid hydrolysis of the ligand. AHA is a strong hydrophilic and selective complexant for the tetravalent actinide ions as evidenced by stability constant and solvent extraction data for An(IV), M(III) and U(VI) ions. This has allowed the successful design of U/Pu+Np separation flowsheets suitable for advanced fuel cycles. (authors)« less

Neutral glycoconjugated amide-based calix[4]arenes: complexation of alkali metal cations in water.

PubMed

Cindro, Nikola; Požar, Josip; Barišić, Dajana; Bregović, Nikola; Pičuljan, Katarina; Tomaš, Renato; Frkanec, Leo; Tomišić, Vladislav

2018-02-07

Cation complexation in water presents a unique challenge in calixarene chemistry, mostly due to the fact that a vast majority of calixarene-based cation receptors is not soluble in water or their solubility has been achieved by introducing functionalities capable of (de)protonation. Such an approach inevitably involves the presence of counterions which compete with target cations for the calixarene binding site, and also rather often requires the use of ion-containing buffer solutions in order to control the pH. Herein we devised a new strategy towards the solution of this problem, based on introducing carbohydrate units at the lower or upper rim of calix[4]arenes which comprise efficient cation binding sites. In this context, we prepared neutral, water-soluble receptors with secondary or tertiary amide coordinating groups, and studied their complexation with alkali metal cations in aqueous and methanol (for the comparison purpose) solutions. Complexation thermodynamics was quantitatively characterized by UV spectrometry and isothermal titration calorimetry, revealing that one of the prepared tertiary amide derivatives is capable of remarkably efficient (log K ≈ 5) and selective binding of sodium cations among alkali metal cations in water. Given the ease of the synthetic procedure used, and thus the variety of accessible analogues, this study can serve as a platform for the development of reagents for diverse purposes in aqueous media.

40 CFR 145.23 - Program description.

Code of Federal Regulations, 2013 CFR

2013-07-01

... and any State administrative or judicial review procedures. (d) Copies of the permit form(s... reviewing the wells for compliance with applicable monitoring, reporting, construction, and financial... for Class II enhanced oil recovery or enhanced gas recovery wells transitioning to Class VI injection...

40 CFR 145.23 - Program description.

Code of Federal Regulations, 2012 CFR

2012-07-01

... and any State administrative or judicial review procedures. (d) Copies of the permit form(s... reviewing the wells for compliance with applicable monitoring, reporting, construction, and financial... for Class II enhanced oil recovery or enhanced gas recovery wells transitioning to Class VI injection...

40 CFR 145.23 - Program description.

Code of Federal Regulations, 2014 CFR

2014-07-01

... and any State administrative or judicial review procedures. (d) Copies of the permit form(s... reviewing the wells for compliance with applicable monitoring, reporting, construction, and financial... for Class II enhanced oil recovery or enhanced gas recovery wells transitioning to Class VI injection...

40 CFR 145.23 - Program description.

Code of Federal Regulations, 2011 CFR

2011-07-01

... and any State administrative or judicial review procedures. (d) Copies of the permit form(s... reviewing the wells for compliance with applicable monitoring, reporting, construction, and financial... for Class II enhanced oil recovery or enhanced gas recovery wells transitioning to Class VI injection...

40 CFR 267.56 - What are the required emergency procedures for the emergency coordinator?

Code of Federal Regulations, 2010 CFR

2010-07-01

... hazardous surface water run-off from water or chemical agents used to control fire and heat-induced...) The extent of injuries, if any. (vi) The possible hazards to human health or the environment outside...

Assembly of a basket-like {Sr ⊂ P6Mo18O73} cage from 0D dimmer to 2D network and its photo-/electro-catalytic properties.

PubMed

Zhang, He; Lv, Jing-Hua; Yu, Kai; Wang, Chun-mei; Wang, Chun-xiao; Sun, Di; Zhou, Bai-bin

2015-07-28

A series of basket-like heteropoly blues, formulated as (H4bth)[{Cu(H2O)}2{Sr ⊂ P6MoV2MoVI16O73}]·4H2O (1), {H2bih}3[{FeII(H2O)2}{Sr ⊂ P6MoV2MoVI16O73}]·2H2O (2), (H2bih)3[{CoII(H2O)2}{Sr ⊂ P6MoV2MoVI16O73}]·2H2O (3), (H2bih)3[{NiII(H2O)2}{Sr ⊂ P6MoV2MoVI16O73}]·2H2O (4), (H2bih)2(H2bip)[{Zn (H2O)0.5}{Sr ⊂ P6MoV2MoVI16O73}]·5.5H2O (5), (bth = 1,6-bis(triazole)hexane; bih = 1,6-bis(imidazol)hexane; bip = 1,5-bis(imidazol)pentane) have been synthesized hydrothermally and fully characterized. The structural analysis shows that all the compounds contain two electron reduced polyanions [Sr ⊂ P6MoV2MoVI16O73]8− (abbreviated as {P6Mo18O73}), which consists of a tetra vacant γ-Dawson-type{P2Mo14} unit and a “handle”-shaped {P4Mo4} segment encapsulating a Sr2+ cation in the central cavity. Compound 1 is a 6-connected two-dimensional (2D) layer, which represents the first 2D assembly of basket-type polyoxometalates. Compounds 2–4 are isostructural one-dimensional zigzag chains linked by an M(H2O)2 linker (M = iron for 2, cobalt for 3, and nickel for 4). Compound 5 is a dimeric cluster supported by a binuclear {Zn2(H2O)} unit. The optical band gaps of 1–5 reveal their semiconductive natures. The compounds if used as photocatalysts exhibit a universal high efficiency degradation ability for dyes such as methylene blue, Rhodamine B, and Azon phloxine. The lifetime and reaction mechanism of the catalysts were investigated with a series of experiments. The compounds also show good bifunctional electrocatalytic behavior for the oxidation of ascorbic acid (AA) and reduction of nitrite ions.

Validation of an electrothermal atomization atomic absorption spectrometry method for quantification of total chromium and chromium(VI) in wild mushrooms and underlying soils.

PubMed

Figueiredo, Estela; Soares, M Elisa; Baptista, Paula; Castro, Marisa; Bastos, M Lourdes

2007-08-22

An ETAAS method was validated to quantify total Cr and Cr(VI) in mushrooms and the underlying soils. The method includes a sample pretreatment for total Cr dissolution using a wet acid digestion procedure and a selective alkaline extraction for Cr(VI). The limits of detection were, expressed in microg/L, 0.15 and 0.17 for total Cr and Cr(VI), respectively. The linearity ranges under the optimized conditions were 0.15-25.0 and 0.17-20.0 microg/L for total Cr and Cr(VI), respectively. The limits of quantification were, expressed in microg/g of dry weight, 0.0163 and 0.0085 for total and hexavalent chromium, respectively. The precision of the instrumental method for total Cr and Cr(VI) was lower than 1.6%, and for the analytical method, it was lower than 10%. The accuracy of the method for Cr(VI) quantification was evaluated by the standard additions method, with the recoveries being higher than 90% for all of the added concentrations. For total Cr, certified reference materials (lichen CRM 482 and soil sample NCS ZC73001) were used. An interference study was also carried out in a mushroom simulated matrix, and it was verified that the deviations of the expected values were lower than 4.0% for both total Cr and Cr(VI). The validated method was applied to the evaluation of total Cr and Cr(VI) in 34 wild mushrooms and 34 respective underlying soil samples collected in two different regions of Portugal (Beira Interior and TrAs-os-Montes), with different locations regarded as noncontaminated or contaminated areas. The species were identified by a mycologist and subdivided into 10 genera and 15 species: Amanita (rubescens, muscaria, and ponderosa), Boletus (regius), Lactarius (deliciosus, vellereus, and piperatus), Suillus (granulatus and luteus), Tricholoma (acerbum), Agaricus (sylvicola), Volvariella (gloiocephala), Lecopaxillus (giganteus), Macrolepiota (procera), and Psilocybe (fascicularis). The mean values found for total Cr were 1.14 and 1.11 microg/g of dry weight, and for Cr(VI), the mean values were 0.103 and 0.143 microg/g of dry weight for cap and stalk, respectively. For soils, the mean concentrations found were, for total Cr, 84.0 microg/g and, for Cr(VI), 0.483 microg/g. The bioconcentration factors (BCFs) based on dry weight for cap and stalk were determined, and the values found, for both total Cr and Cr(VI), were always <1, although for hexavalent chromium, the BCFs were 10 times higher than for total chromium.

Verification, Validation, and Solution Quality in Computational Physics: CFD Methods Applied to Ice Sheet Physics

NASA Technical Reports Server (NTRS)

Thompson, David E.

2005-01-01

Procedures and methods for veri.cation of coding algebra and for validations of models and calculations used in the aerospace computational fluid dynamics (CFD) community would be ef.cacious if used by the glacier dynamics modeling community. This paper presents some of those methods, and how they might be applied to uncertainty management supporting code veri.cation and model validation for glacier dynamics. The similarities and differences between their use in CFD analysis and the proposed application of these methods to glacier modeling are discussed. After establishing sources of uncertainty and methods for code veri.cation, the paper looks at a representative sampling of veri.cation and validation efforts that are underway in the glacier modeling community, and establishes a context for these within an overall solution quality assessment. Finally, a vision of a new information architecture and interactive scienti.c interface is introduced and advocated.

Assessment of ferrous chloride and Portland cement for the remediation of chromite ore processing residue.

PubMed

Jagupilla, Santhi C; Wazne, Mahmoud; Moon, Deok Hyun

2015-10-01

Chromite Ore Processing Residue (COPR) is an industrial waste containing up to 7% chromium (Cr) including up to 5% hexavalent chromium [Cr(VI)]. The remediation of COPR has been challenging due to the slow release of Cr(VI) from a clinker like material and thereby the incomplete detoxification of Cr(VI) by chemical reagents. The use of sulfur based reagents such as ferrous sulfate and calcium polysulfide to detoxify Cr(VI) has exasperated the swell potential of COPR upon treatment. This study investigated the use of ferrous chloride alone and in combination with Portland cement to address the detoxification of Cr(VI) in COPR and the potential swell of COPR. Chromium regulatory tests, X-ray powder diffraction (XRPD) analyses and X-ray absorption near edge structure (XANES) analyses were used to assess the treatment results. The treatment results indicated that Cr(VI) concentrations for the acid pretreated micronized COPR as measured by XANES analyses were below the New Jersey Department of Environmental Protection (NJDEP) standard of 20 mg kg(-1). The Toxicity characteristic leaching procedure (TCLP) Cr concentrations for all acid pretreated samples also were reduced below the TCLP regulatory limit of 5 mg L(-1). Moreover, the TCLP Cr concentration for the acid pretreated COPR with particle size ⩽0.010 mm were less than the universal treatment standard (UTS) of 0.6 mg L(-1). The treatment appears to have destabilized all COPR potential swell causing minerals. The unconfined compressive strength (UCS) for the treated samples increased significantly upon treatment with Portland cement. Copyright © 2015 Elsevier Ltd. All rights reserved.

28 CFR 42.405 - Public dissemination of title VI information.

Code of Federal Regulations, 2014 CFR

2014-07-01

... information. 42.405 Section 42.405 Judicial Administration DEPARTMENT OF JUSTICE NONDISCRIMINATION; EQUAL EMPLOYMENT OPPORTUNITY; POLICIES AND PROCEDURES Coordination of Enforcement of Non-discrimination in... insure that such publications and broadcasts state that the program in question is an equal opportunity...

12 CFR 222.1 - Purpose, scope, and effective dates.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) Section 114, concerning procedures for the identification of possible instances of identity theft; (iii...)(1), concerning the summary of rights of identity theft victims; (v) Section 152, concerning blocking of information resulting from identity theft; (vi) Section 153, concerning the coordination of...

14 CFR 437.55 - Hazard analysis.

Code of Federal Regulations, 2014 CFR

2014-01-01

... TRANSPORTATION LICENSING EXPERIMENTAL PERMITS Safety Requirements § 437.55 Hazard analysis. (a) A permittee must...) Design inadequacies; or (vi) Procedural deficiencies. (2) Determine the likelihood of occurrence and... include one or more of the following: (i) Designing for minimum risk, (ii) Incorporating safety devices...

14 CFR 437.55 - Hazard analysis.

Code of Federal Regulations, 2010 CFR

2010-01-01

... TRANSPORTATION LICENSING EXPERIMENTAL PERMITS Safety Requirements § 437.55 Hazard analysis. (a) A permittee must...) Design inadequacies; or (vi) Procedural deficiencies. (2) Determine the likelihood of occurrence and... include one or more of the following: (i) Designing for minimum risk, (ii) Incorporating safety devices...

14 CFR 437.55 - Hazard analysis.

Code of Federal Regulations, 2011 CFR

2011-01-01

... TRANSPORTATION LICENSING EXPERIMENTAL PERMITS Safety Requirements § 437.55 Hazard analysis. (a) A permittee must...) Design inadequacies; or (vi) Procedural deficiencies. (2) Determine the likelihood of occurrence and... include one or more of the following: (i) Designing for minimum risk, (ii) Incorporating safety devices...

17 CFR 39.5 - Review of swaps for Commission determination on clearing requirement.

Code of Federal Regulations, 2013 CFR

2013-04-01

... publicly; (vi) Risk management procedures, including measurement and monitoring of credit exposures... derivative clearing organization's ability to manage the risks associated with clearing the swap, especially... of rule framework, capacity, operational expertise and resources, and credit support infrastructure...

17 CFR 39.5 - Review of swaps for Commission determination on clearing requirement.

Code of Federal Regulations, 2014 CFR

2014-04-01

... publicly; (vi) Risk management procedures, including measurement and monitoring of credit exposures... derivative clearing organization's ability to manage the risks associated with clearing the swap, especially... of rule framework, capacity, operational expertise and resources, and credit support infrastructure...

K2Ho(PO4)(WO4)

PubMed Central

Terebilenko, Katherina V.; Zatovsky, Igor V.; Baumer, Vyacheslav N.; Slobodyanik, Nikolay S.; Shishkin, Oleg V.

2008-01-01

A new compound, dipotassium holmium(III) phosphate(V) tungstate(VI), K2Ho(PO4)(WO4), has been obtained during investigation of the K2O–P2O5–WO3–HoF3 phase system using the flux technique. The compound is isotypic with K2Bi(PO4)(WO4). Its framework structure consists of flat ∞ 2[HoPO4] layers parallel to (100) that are made up of ∞ 1[HoO8] zigzag chains inter­linked via slightly distorted PO4 tetra­hedra. WO4 tetra­hedra are attached above and below these layers, leaving space for the K+ counter-cations. The HoO8, PO4 and WO4 units exhibit 2 symmetry. PMID:21580811

Mineral transformations during the dissolution of uranium ore minerals by dissimilatory metal-reducing bacteria

NASA Astrophysics Data System (ADS)

Glasauer, S.; Weidler, P.; Fakra, S.; Tyliszczak, T.; Shuh, D.

2011-12-01

Carnotite minerals [X2(UO2)2(VO4)2]; X = K, Ca, Ba, Mn, Na, Cu or Pb] form the major ore of uranium in the Colorado Plateau. These deposits are highly oxidized and contain U(VI) and V(IV). The biotransformation of U(VI) bound in carnotite by bacteria during dissimilatory metal reduction presents a complex puzzle in mineral chemistry. Both U(VI) and V(V) can be respired by metal reducing bacteria, and the mineral structure can change depending on the associated counterion. We incubated anaerobic cultures of S. putrefaciens CN32 with natural carnotite minerals from southeastern Utah in a nutrient-limited defined medium. Strain CN32 is a gram negative bacterium and a terrestrial isolate from New Mexico. The mineral and metal transformations were compared to a system that contained similar concentrations of soluble U(VI) and V(V). Electron (SEM, TEM) microscopies and x-ray spectromicroscopy (STXM) were used in conjunction with XRD to track mineral changes, and bacterial survival was monitored throughout the incubations. Slow rates of metal reduction over 10 months for the treatment with carnotite minerals revealed distinct biotic and abiotic processes, providing insight on mineral transformation and bacteria-metal interactions. The bacteria existed as small flocs or individual cells attached to the mineral phase, but did not adsorb soluble U or V, and accumulated very little of the biominerals. Reduction of mineral V(V) necessarily led to a dismantling of the carnotite structure. Bioreduction of V(V) by CN32 contributed small but profound changes to the mineral system, resulting in new minerals. Abiotic cation exchange within the carnotite group minerals induced the rearrangement of the mineral structures, leading to further mineral transformation. In contrast, bacteria survival was poor for treatments with soluble U(VI) and V(V), although both metals were reduced completely and formed solid UO2 and VO2; we also detected V(III). For these treatments, the bacteria formed extensive biofilms or flocs that contained U and V in the exopolymer, but excluded these metals from the bacteria. This suggests a specific mechanism to inhibit metal sorption to cell wall components. The example illustrates the interplay between bacteria and minerals under conditions that model oligotrophic survival, and provides insight on U mobilization from common uranium ore minerals.

40 CFR 170.130 - Pesticide safety training for workers.

Code of Federal Regulations, 2010 CFR

2010-07-01

... restricted-entry interval applies, including but not limited to, soil, water, or surfaces of plants, the..., soil, irrigation water, or drifting from nearby applications. (2) Prevent pesticides from entering your... poisonings. (vi) How to obtain emergency medical care. (vii) Routine and emergency decontamination procedures...

23 CFR 200.1 - Purpose.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 23 Highways 1 2011-04-01 2011-04-01 false Purpose. 200.1 Section 200.1 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.1 Purpose. To provide guidelines for: (a) Implementing the Federal Highway...

23 CFR 200.1 - Purpose.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 23 Highways 1 2010-04-01 2010-04-01 false Purpose. 200.1 Section 200.1 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.1 Purpose. To provide guidelines for: (a) Implementing the Federal Highway...

23 CFR 200.1 - Purpose.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 23 Highways 1 2014-04-01 2014-04-01 false Purpose. 200.1 Section 200.1 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.1 Purpose. To provide guidelines for: (a) Implementing the Federal Highway...

23 CFR 200.1 - Purpose.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 23 Highways 1 2013-04-01 2013-04-01 false Purpose. 200.1 Section 200.1 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.1 Purpose. To provide guidelines for: (a) Implementing the Federal Highway...

Resistance to Change and Relapse of Observing

ERIC Educational Resources Information Center

Thrailkill, Eric A.; Shahan, Timothy A.

2012-01-01

Four experiments examined relapse of extinguished observing behavior of pigeons using a two-component multiple schedule of observing-response procedures. In both components, unsignaled periods of variable-interval (VI) food reinforcement alternated with extinction and observing responses produced stimuli associated with the availability of the VI…

26 CFR 1.911-7 - Procedural rules.

Code of Federal Regulations, 2010 CFR

2010-04-01

... effective; (v) The exclusion or exclusions the individual is electing; (vi) The foreign country or countries...) The status (either bona fide residence or physical presence) under which the individual claims the exclusion; (viii) The individual's qualifying period of residence or presence; (ix) The individual's foreign...

Methods for Minimization and Management of Variability in Long Term Groundwater Monitoring Results

DTIC Science & Technology

2015-06-01

procedure ACRONYMS AND ABBREVIATIONS (continued) vi TCE trichloroethylene trans-1,2-DCE trans-1,2-dichloroethylene USEPA U.S...following constituents: tetrachloroethylene (PCE), trichloroethylene (TCE), cis-1,2- dichloroethylene (cis-1,2-DCE), vinyl chloride (VC), and 1,1

23 CFR 200.9 - State highway agency responsibilities.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 23 Highways 1 2012-04-01 2012-04-01 false State highway agency responsibilities. 200.9 Section 200.9 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION CIVIL RIGHTS TITLE VI PROGRAM AND RELATED STATUTES-IMPLEMENTATION AND REVIEW PROCEDURES § 200.9 State highway agency...

Optimizing Metalloporphyrin-Catalyzed Reduction Reactions for In Situ Remediation of DOE Contaminants

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

Schlautman, Mark A.

2013-07-14

Past activities have resulted in a legacy of contaminated soil and groundwater at Department of Energy facilities nationwide. Uranium and chromium are among the most frequently encountered and highest-priority metal and radionuclide contaminants at DOE installations. Abiotic chemical reduction of uranium and chromium at contaminated DOE sites can be beneficial because the reduced metal species are less soluble in water, less mobile in the environment, and less toxic to humans and ecosystems. Although direct biological reduction has been reported for U(VI) and Cr(VI) in laboratory studies and at some field sites, the reactions can sometimes be slow or even inhibitedmore » due to unfavorable environmental conditions. One promising approach for the in-situ remediation of DOE contaminants is to develop electron shuttle catalysts that can be delivered precisely to the specific subsurface locations where contaminants reside. Previous research has shown that reduction of oxidized organic and inorganic contaminants often can be catalyzed by electron shuttle systems. Metalloporphyrins and their derivatives are well known electron shuttles for many biogeochemical systems, and thus were selected to study their catalytic capabilities for the reduction of chromium and uranium in the presence of reducing agents. Zero valent iron (ZVI) was chosen as the primary electron donor in most experimental systems. Research proceeded in three phases and the key findings of each phase are reported here. Phase I examined Cr(VI) reduction and utilized micro- and nano-sized ZVI as the electron donors. Electron shuttle catalysts tested were cobalt- and iron-containing metalloporphyrins and Vitamin B12. To aid in the recycle and reuse of the nano-sized ZVI and soluble catalysts, sol-gels and calcium-alginate gel beads were tested as immobilization/support matrices. Although the nano-sized ZVI could be incorporated within the alginate gel beads, preliminary attempts to trap it in sol-gels were not successful. Conversely, the water-soluble catalysts could be trapped within sol-gel matrices but they tended to leach out of the alginate gel beads during use. In general, immobilization of the nano-sized ZVI in gel beads and of the catalysts in sol-gels tended to result in slower rates of Cr(VI) reduction, but these effects could be overcome to some extent by using higher reactant/catalyst concentrations. In addition, the lowering of their effectiveness would likely be offset by the benefits obtained when recycling and reusing the materials because they were immobilized. Addition of the catalytic electron shuttles will be most useful when the micro-sized or nano-sized ZVI becomes less reactive with reaction time. Continued work in Phase II in the area of nano-sized ZVI immobilization led to procedures that were successful in incorporating the iron particles in sol-gel matrices. The water-soluble reductants sodium dithionite and L-ascorbic acid were also tested, but their use appeared to lead to formation of complexes with the uranyl cation which limited their effectiveness. Also, although the sol-gel supported nano-sized ZVI showed some promise at reducing uranium, the fluoride used in the sol-gel synthesis protocol appeared to lead to formation of uranyl-fluoride complexes that were less reactive. Because hexavalent chromium is an anion which does not form complexes with fluoride, it was used to demonstrate the intrinsic reactivity of the sol-gel immobilized nano-sized ZVI. Consistent with our observations in Phase I, the sol-gel matrix once again slowed down the reduction reaction but the expected benefits of recycle/reuse should outweigh this adverse effect. The major emphasis in Phase III of this study was to simultaneously incorporate nano-sized ZVI and water-soluble catalysts in the same sol-gel matrix. The catalysts utilized were cobalt complexes of uroporphyrin and protoporphyrin and Cr(VI) reduction was used to test the efficacy of the combined "catalyst + reductant" sol-gel matrix. When enough catalyst was added to the sol-gels, enhancement of the Cr(VI) reduction reaction was observed. At the lowest levels of catalyst addition, however, the rates of Cr(VI) reduction were similar to those systems which only used sol-gel immobilized nano-sized ZVI without any catalyst present. These findings suggest future areas of research that should be pursued to further optimize abiotic reduction reactions of metals with combined "catalyst + reductant" matrices.« less

Electron spin resonance (ESR) of magnetic sublattices in Sc-substituted barium hexaferrite

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

Díaz-Pardo, Rebeca; Monjaras, Raúl Valenzuela; Bierlich, Silvia

2016-05-15

The partial substitution of Fe{sup 3+} by Sc{sup 3+} in barium hexaferrite has shown to be an effective method to tailor anisotropy for many novel microwave applications. Some basic studies have revealed that this substitution leads to unusual interactions among the magnetic sublattices of the ferrite. In order to investigate these interactions, samples with formula BaSc{sub x}Fe{sub 12-x}O{sub 19} (1 ≤x ≤ 2) were prepared by sintering (1300°C, 6h). After structural characterization by x-ray diffraction, their ferromagnetic resonance spectra were measured in the X-band (9.4 GHz), in the 100-500 K temperature range. For x = 2, a single, broad resonancemore » peak was observed at the low temperatures (103 K), exhibiting a progressive splitting into two peaks for increasing T, to finally coalesce again into a single (paramagnetic) narrow peak at 473 K. These results are interpreted in terms of a substitution of Fe{sup 3+} by Sc{sup 3+} ions in the 4f{sub vi} and 2b sublattices; the diamagnetic cations disrupt the superexchange interactions and produce a splitting of the 12k sublattice (which interacts directly with the 4f{sub vi} sublattice) into two sublattices with different canting angles, and different thermal dependence. As a result, the fraction of the 12k sublattices that are nearest neighbours of substituted 4f{sub vi} sites can behave as an independent sublattice for some temperature ranges. A similar behavior is observed for all the compositions with varying degrees of amplitude, but it is more evident for x = 2. A deconvolution of peaks has been attempted, in order to shed more light into this behavior.« less

Rapid removal of uranium from aqueous solutions using magnetic Fe3O4@SiO2 composite particles.

PubMed

Fan, Fang-Li; Qin, Zhi; Bai, Jing; Rong, Wei-Dong; Fan, Fu-You; Tian, Wei; Wu, Xiao-Lei; Wang, Yang; Zhao, Liang

2012-04-01

Rapid removal of U(VI) from aqueous solutions was investigated using magnetic Fe(3)O(4)@SiO(2) composite particles as the novel adsorbent. Batch experiments were conducted to study the effects of initial pH, amount of adsorbent, shaking time and initial U(VI) concentrations on uranium sorption efficiency as well as the desorbing of U(VI). The sorption of uranium on Fe(3)O(4)@SiO(2) composite particles was pH-dependent, and the optimal pH was 6.0. In kinetics studies, the sorption equilibrium can be reached within 180 min, and the experimental data were well fitted by the pseudo-second-order model, and the equilibrium sorption capacities calculated by the model were almost the same as those determined by experiments. The Langmuir sorption isotherm model correlates well with the uranium sorption equilibrium data for the concentration range of 20-200 mg/L. The maximum uranium sorption capacity onto magnetic Fe(3)O(4)@SiO(2) composite particles was estimated to be about 52 mg/g at 25 °C. The highest values of uranium desorption (98%) was achieved using 0.01 M HCl as the desorbing agent. Fe(3)O(4)@SiO(2) composite particles showed a good selectivity for uranium from aqueous solution with other interfering cation ions. Present study suggested that magnetic Fe(3)O(4)@SiO(2) composite particles can be used as a potential adsorbent for sorption uranium and also provided a simple, fast separation method for removal of heavy metal ion from aqueous solution. Copyright © 2011 Elsevier Ltd. All rights reserved.

28 CFR 902.3 - Referral to Dispute Resolution Committee.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Referral to Dispute Resolution Committee... DISPUTE ADJUDICATION PROCEDURES § 902.3 Referral to Dispute Resolution Committee. (a) The five person Dispute Resolution Committee membership shall be determined according to Compact Article VI (g). Should a...

33 CFR 106.305 - Facility Security Assessment (FSA) requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... available to maintain essential services; (vi) The essential maintenance equipment and storage areas; (vii... procedures relating to essential services; (v) Measures to protect radio and telecommunication equipment... property, or economic disruption, of an attack on or at the OCS facility; and (7) Locations where access...

Joint Tactics, Techniques, and Procedures for Antiterrorism

DTIC Science & Technology

1998-03-17

VI-5 VII-1 Fortification Materials...concealment and inability to create perimeter stand-off. Political restrictions may also limit the military’s ability to construct fortifications or... fortifications , sensors, obstacles, local-hire security forces (if applicable), unit guards, deception, and on-call support from reaction forces. Each

45 CFR 81.1 - Scope of rules.

Code of Federal Regulations, 2012 CFR

2012-10-01

... administrative review conducted by the Department of Health and Human Services, pursuant to Title VI of the Civil Rights Act of 1964 (section 602, 78 Stat. 252) and Part 80 of this subtitle. ... DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PRACTICE AND PROCEDURE FOR HEARINGS UNDER PART...

45 CFR 81.1 - Scope of rules.

Code of Federal Regulations, 2014 CFR

2014-10-01

... administrative review conducted by the Department of Health and Human Services, pursuant to Title VI of the Civil Rights Act of 1964 (section 602, 78 Stat. 252) and part 80 of this subtitle. ... Department of Health and Human Services GENERAL ADMINISTRATION PRACTICE AND PROCEDURE FOR HEARINGS UNDER PART...

45 CFR 81.1 - Scope of rules.

Code of Federal Regulations, 2011 CFR

2011-10-01

... administrative review conducted by the Department of Health and Human Services, pursuant to Title VI of the Civil Rights Act of 1964 (section 602, 78 Stat. 252) and Part 80 of this subtitle. ... DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PRACTICE AND PROCEDURE FOR HEARINGS UNDER PART...

45 CFR 81.1 - Scope of rules.

Code of Federal Regulations, 2013 CFR

2013-10-01

... administrative review conducted by the Department of Health and Human Services, pursuant to Title VI of the Civil Rights Act of 1964 (section 602, 78 Stat. 252) and Part 80 of this subtitle. ... DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PRACTICE AND PROCEDURE FOR HEARINGS UNDER PART...

45 CFR 81.1 - Scope of rules.

Code of Federal Regulations, 2010 CFR

2010-10-01

... administrative review conducted by the Department of Health and Human Services, pursuant to Title VI of the Civil Rights Act of 1964 (section 602, 78 Stat. 252) and Part 80 of this subtitle. ... DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PRACTICE AND PROCEDURE FOR HEARINGS UNDER PART...

40 CFR 63.306 - Work practice standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... November 15, 1993, each owner or operator shall prepare and submit a written emission control work practice... inspections, the method to be used to evaluate conformance with operating specifications for each type of... with hand-luted doors, procedures for luting and reluting, as necessary to prevent exceedances; (vi...

34 CFR 366.37 - What procedures does the Director of the DSU (Director) use in making a grant for a new center?

Code of Federal Regulations, 2010 CFR

2010-07-01

... involvement of individuals with significant disabilities by the applicant. (v) The budget and cost-effectiveness of the applicant. (vi) The evaluation plan of the applicant. (vii) The ability of the applicant to...

29 CFR 1691.13 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... a complaint of employment discrimination covered by title VII or the Equal Pay Act and by title VI... Relating to Labor (Continued) EQUAL EMPLOYMENT OPPORTUNITY COMMISSION PROCEDURES FOR COMPLAINTS OF... Department of Justice, or his or her delegate. (c) Chairman of the EEOC refers to the Chairman of the Equal...

42 CFR 456.380 - Individual written plan of care.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICES (CONTINUED) MEDICAL ASSISTANCE PROGRAMS UTILIZATION CONTROL Utilization Control: Intermediate Care Facilities Plan of Care § 456.380 Individual written plan of care. (a) Before admission to an ICF or before...) Activities; (v) Therapies; (vi) Social services; (vii) Diet; and (viii) Special procedures designed to meet...

42 CFR 456.380 - Individual written plan of care.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SERVICES (CONTINUED) MEDICAL ASSISTANCE PROGRAMS UTILIZATION CONTROL Utilization Control: Intermediate Care Facilities Plan of Care § 456.380 Individual written plan of care. (a) Before admission to an ICF or before...) Activities; (v) Therapies; (vi) Social services; (vii) Diet; and (viii) Special procedures designed to meet...

Introduction to Systematic Instruction. (SCAT Project, Title VI-G).

ERIC Educational Resources Information Center

Idaho State Dept. of Education, Boise.

Developed by the staff of SCAT (Support, Competency-Assistance and Training), the document provides information on systematic instructional procedures for teachers of exceptional children. Briefly addressed are the seven components of systematic instruction: initial assessment, establishment of long term goals, sequencing of short term objectives,…

Conditioned Reinforcement Value and Resistance to Change

ERIC Educational Resources Information Center

Shahan, Timothy A.; Podlesnik, Christopher A.

2008-01-01

Three experiments examined the effects of conditioned reinforcement value and primary reinforcement rate on resistance to change using a multiple schedule of observing-response procedures with pigeons. In the absence of observing responses in both components, unsignaled periods of variable-interval (VI) schedule food reinforcement alternated with…

32 CFR 231.5 - Procedures-domestic banks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... to the TGA. (vi) A list of organizational and nonappropriated fund accounts, the name and location of... surveillance equipment, when necessary. (ix) Reasons for use of space controlled by the General Services... solicitation. Proposals shall be evaluated and ultimate selection made based upon the factors and weights...

45 CFR 611.8 - Procedure for effecting compliance.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 611.8 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE FOUNDATION NONDISCRIMINATION IN FEDERALLY-ASSISTED PROGRAMS OF THE NATIONAL SCIENCE FOUNDATION-EFFECTUATION OF TITLE VI OF THE... shall be limited to the particular political entity, or part thereof, or other applicant or recipient as...

Design of the first optical system for real-time tomographic holography (RTTH)

NASA Astrophysics Data System (ADS)

Galeotti, John M.; Siegel, Mel; Rallison, Richard D.; Stetten, George

2008-08-01

The design of the first Real-Time-Tomographic-Holography (RTTH) optical system for augmented-reality applications is presented. RTTH places a viewpoint-independent real-time (RT) virtual image (VI) of an object into its actual location, enabling natural hand-eye coordination to guide invasive procedures, without requiring tracking or a head-mounted device. The VI is viewed through a narrow-band Holographic Optical Element (HOE) with built-in power that generates the largest possible near-field, in-situ VI from a small display chip without noticeable parallax error or obscuring direct view of the physical world. Rigidly fixed upon a medical-ultrasound probe, RTTH could show the scan in its actual location inside the patient, because the VI would move with the probe. We designed the image source along with the system-optics, allowing us to ignore both planer geometric distortions and field curvature, respectively compensated by using RT pre-processing software and attaching a custom-surfaced fiber-optic-faceplate (FOFP) to our image source. Focus in our fast, non-axial system was achieved by placing correcting lenses near the FOFP and custom-optically-fabricating our volume-phase HOE using a recording beam that was specially shaped by extra lenses. By simultaneously simulating and optimizing the system's playback performance across variations in both the total playback and HOE-recording optical systems, we derived and built a design that projects a 104x112 mm planar VI 1 m from the HOE using a laser-illuminated 19x16 mm LCD+FOFP image-source. The VI appeared fixed in space and well focused. Viewpoint-induced location errors were <3 mm, and unexpected first-order astigmatism produced 3 cm (3% of 1 m) ambiguity in depth, typically unnoticed by human observers.

Method for the determination of chromium in feed matrix by HPLC.

PubMed

Umesh, Balakrishnan; Rajendran, Rajendra Moorthy; Manoharan, Muthu Tamizh

2015-11-01

An improved method for the chromatographic separation and determination of chromium (III) and (VI) [ CRIII AND CRVI: ] in mineral mixtures and feed samples has been developed. The method uses precolumn derivatization using ammonium pyrrolidinedithiocarbamate ( APD: ) followed by reversed-phase liquid chromatography to separate the chromium ions. Both Cr(III) and Cr(VI) species are chelated with ammonium pyrrolidinedithiocarbamate prior to separation by mixing with acetonitrile and 0.5 mmol acetate buffer (pH 4.5). Optimum chromatographic separations were obtained with a polymer-based reversed-phase column (Kinetex, 5 μ, 250 × 4.5 mm, Phenomenex, Torrance, CA) and a mobile phase containing acetonitrile and water (7:3). Both Cr(III) and Cr(VI) ion concentrations were directly determined from the corresponding areas in the chromatogram. The effect of analytical parameters, including pH, concentration of ligand, incubation temperature, and mobile phase, was optimized for both chromium complexes. The range of the procedure was found to be linear for Cr(III) and Cr(VI) concentrations between 0.125 and 4 μg/mL (r² = 0.9926) and 0.1 and 3.0 μg/mL (r² = 0.9983), respectively. Precision was evaluated by replicate analysis in which the percentage relative standard deviation values for chromium complex were found to be below 4.0. The recoveries obtained (85-115%) for both Cr(III) and Cr(VI) complexes indicated the accuracy of the developed method. The degradation products, as well as the excipients, were well resolved from the chromium complex peak in the chromatogram. Finally, the new method proved to be suitable for routine analysis of Cr(III) and Cr(VI) species in raw materials, mineral mixtures, and feed samples. © 2015 Poultry Science Association Inc.

Quantification of the toxic hexavalent chromium content in an organic matrix by X-ray photoelectron spectroscopy (XPS) and ultra-low-angle microtomy (ULAM)

NASA Astrophysics Data System (ADS)

Greunz, Theresia; Duchaczek, Hubert; Sagl, Raffaela; Duchoslav, Jiri; Steinberger, Roland; Strauß, Bernhard; Stifter, David

2017-02-01

Cr(VI) is known for its corrosion inhibitive properties and is, despite legal regulations, still a potential candidate to be added to thin (1-3 μm) protective coatings applied on, e.g., electrical steel as used for transformers, etc. However, Cr(VI) is harmful to the environment and to the human health. Hence, a reliable quantification of it is of decisive interest. Commonly, an alkaline extraction with a photometric endpoint detection of Cr(VI) is used for such material systems. However, this procedure requires an accurate knowledge on sample parameters such as dry film thickness and coating density that are occasionally associated with significant experimental errors. We present a comprehensive study of a coating system with a defined Cr(VI) pigment concentration applied on electrical steel. X-ray photoelectron spectroscopy (XPS) was employed to resolve the elemental chromium concentration and the chemical state. Turning to the fact that XPS is extremely surface sensitive (<10 nm) and that the lowest commonly achievable lateral resolution is a number of times higher than the coating thickness (∼2 μm), a bulk analysis was achieved with XPS line scans on extended wedge-shaped tapers through the coating. For that purpose a special sample preparation step performed on an ultra-microtome was required prior to analysis. Since a temperature increase leads to a reduction of Cr(VI) we extend our method on samples, which were subjected to different curing temperatures. We show that our proposed approach now allows to determine the elemental and Cr(VI) concentration and distribution inside the coating.

Problems of Determining the Content of Cr(VI) in Raw Materials and Materials Containing Chromite Ore.

PubMed

Stec, Katarzyna

2017-11-02

Materials made with chromite ore are widely applied in the industry metallurgy as well as in the foundry industry. The oxidation number of chromium in these materials is both (III) and (VI). Currently there are no procedures allowing proper determination of chrome in chromite ores and ore-containing materials. The analytical methods applied, which are dedicated to a very narrow range of materials, e.g., cement, and cannot be applied in the case of materials which, apart from trace amounts of Cr(VI), contain mainly compounds of Cr(III), Fe(III) as well as trace compounds of Cu(II), Ni(II) and V(V). In the work particular attention has been paid to the preparation of test samples and creating measurement conditions in which interferences from Cr(III) and Fe(III) spectral lines could be minimized. Two separate instrumental measurement techniques have been applied: Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP AES) and the spectrophotometric method using diphenylcarbazide.

Prevalence of visual impairment and outcomes of cataract surgery in Chaonan, South China

PubMed Central

Zhang, Xiujuan; Li, Emmy Y.; Leung, Christopher Kai-Shun; Musch, David C.; Tang, Xin; Zheng, Chongren; He, Mingguang; Chang, David F.

2017-01-01

Purpose To estimate the prevalence and causes of blindness and visual impairment (VI), and report the outcomes of cataract surgery in Chaonan Region, Guangdong Province, southern China Design Cross-sectional population-based survey Participants A total of 3484 participants including 1397 men (40.1%) and 2087 women (59.9%) aged ≥50 years were examined (94.2% response rate). Method A two-stage cluster sampling procedure was used to select 3700 participants aged ≥50 years from 74 clusters of Chaonan Region. Participants were examined according to the Rapid Assessment of Avoidable Blindness (RAAB) method. Blindness and visual impairment (VI) were defined by the World Health Organization criteria. Participants with visual acuity (VA) < 6/18 in either eye were examined by ophthalmologists. The primary causes of blindness and VI were reported with reference to the participant’s better eye. Main outcome measures Prevalence and main causes of blindness, severe visual impairment (SVI), VI and the outcomes of cataract surgery Results The standardized prevalence rates of blindness, SVI, and VI were 2.4% (95% confidence interval [CI], 1.9–2.9%), 1.0% (95% CI, 0.7–1.4%), and 6.4% (95% CI, 5.6%– 7.1%), respectively. The principal cause of blindness and SVI was cataract, accounting for 67.1% and 67.6% respectively, and the principal cause of VI was refractive error (46.9%). One hundred and fifty five out of 3484 (4.4%) people (211 eyes) had cataract surgery. Of the 211 eyes that had cataract surgery, 96.7% were pseudophakic. 67.2% of the 211 operated eyes had a presenting visual acuity (PVA) of 6/18 or better. Conclusions The prevalence of blindness, SVI, and VI was high among rural residents in Chaonan. Cataract remained the leading cause of avoidable blindness. Outcomes of cataract surgery performed in rural private clinics were suboptimal. Quality-control initiatives such as hands-on training program should be introduced to improve cataract surgery outcomes. PMID:28797099

The role of response force on the persistence and structure of behavior during extinction.

PubMed

Pinkston, Jonathan W; Foss, Erica K

2018-01-01

Behavior Momentum Theory has emerged as a prominent account of resistance to change in both basic and applied research. Although laboratory studies often define precise, repeatable responses, application research often deals with response classes that may vary widely along a number of dimensions. In general, Behavior Momentum Theory has not addressed how response dimensions impact resistance to change, providing an opportunity to expand the model in new directions. Four rats pressed a force transducer under a multiple variable interval (VI) 60-s VI 60-s schedule of reinforcement. In one component, responses satisfied the schedule only if the response force fell within a "low" force band requirement; responses in the other schedule were required to satisfy a "high" force band. Once responding stabilized, extinction was programmed for three sessions. Then, the procedures were replicated. The results showed that response force came under discriminative control, but force requirements had no impact on resistance to extinction. In a follow-up condition, the schedule was changed to a multiple VI 30-s VI 120-s schedule and the low-force band operated in both components. The results showed that behavior maintained by the VI 30-s schedule was generally more resistant to extinction. A secondary analysis showed that force distributions created under baseline maintained during extinction. Overall, the results suggest that differential response force requirements prevailing in steady state do not affect the course of extinction. © 2018 Society for the Experimental Analysis of Behavior.

Ship-in-a-bottle CMPO in MIL-101(Cr) for selective uranium recovery from aqueous streams through adsorption.

PubMed

De Decker, Jeroen; Folens, Karel; De Clercq, Jeriffa; Meledina, Maria; Van Tendeloo, Gustaaf; Du Laing, Gijs; Van Der Voort, Pascal

2017-08-05

Mesoporous MIL-101(Cr) is used as host for a ship-in-a-bottle type adsorbent for selective U(VI) recovery from aqueous environments. The acid-resistant cage-type MOF is built in-situ around N,N-Diisobutyl-2-(octylphenylphosphoryl)acetamide (CMPO), a sterically demanding ligand with high U(VI) affinity. This one-step procedure yields an adsorbent which is an ideal compromise between homogeneous and heterogeneous systems, where the ligand can act freely within the pores of MIL-101, without leaching, while the adsorbent is easy separable and reusable. The adsorbent was characterized by XRD, FTIR spectroscopy, nitrogen adsorption, XRF, ADF-STEM and EDX, to confirm and quantify the successful encapsulation of the CMPO in MIL-101, and the preservation of the host. Adsorption experiments with a central focus on U(VI) recovery were performed. Very high selectivity for U(VI) was observed, while competitive metal adsorption (rare earths, transition metals...) was almost negligible. The adsorption capacity was calculated at 5.32mg U/g (pH 3) and 27.99mg U/g (pH 4), by fitting equilibrium data to the Langmuir model. Adsorption kinetics correlated to the pseudo-second-order model, where more than 95% of maximum uptake is achieved within 375min. The adsorbed U(VI) is easily recovered by desorption in 0.1M HNO 3 . Three adsorption/desorption cycles were performed. Copyright © 2017 Elsevier B.V. All rights reserved.

Selective separation of uranium using alizarin red S (ARS)-modified anion-exchange resin or by flotation of U-ARS chelate

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

Khalifa, M.E.

An alizarin red S (ARS)-modified anion exchange resin was prepared by a simple reaction of ARS with the anion exchange Doulite A101 and used for the efficient sorption of uranium from aqueous media. The effect of various parameters on the sorption of U(VI) (pH effect, sorption kinetics, resin capacity and breakthrough curves) was investigated. The modified resin sorbs U(VI) over a wide range of pH (2.8--5) with a maximum sorption capacity of 0.68 mmol/g at pH 3.2 to 4.0. Iron(III), Zr(IV), Ti(IV), Cu(II), and Th(IV) ions are also sorbed to different extents, but Be(II), Bi(III), Ca(II), Mg(II), Pb(II), Hg(II), Zn(II),more » Cd(II), Al(III), Mn(II), Co(II) and Ni(II) are not sorbed; thus, conditions for separating U(VI) from these metal ions have been identified. For eluting U(VI) from the resin, 0.2 mol/L HCl was used and the recovery recorded was as high as 99.9%. The use of ARS is extended to float uranium quantitatively and selectively from aqueous media at pH {approx} 4 by using oleic acid as a surfactant. The different parameters affecting the flotation process have also been investigated. Uranium(VI) has been effectively separated from natural water samples and certified uranium ores using both procedures.« less

42 CFR 423.44 - Involuntary disenrollment by the PDP.

Code of Federal Regulations, 2010 CFR

2010-10-01

... expertise reviews the case before making a final decision. The PDP sponsor is required to provide a... deems necessary. CMS notifies the PDP sponsor within 5 working days after making its decision. (vi... disenroll affected enrollees in accordance with the procedures for disenrollment set forth at § 423.507...

Leader Behavior of Head Nurses through the Perceptions of Self and Others.

DTIC Science & Technology

1984-01-01

studies ......... 17 III. Methodology .. ....... ...... ......................... 25 Population and sample ........ .*... ............ . 25 Procedures...60....*.* Implications for future rsearch ............. 62 Implications for nursing comaunity...*................. 63 *.......****.*** 75 Vi List...able to distinguish the personality traits of leaders from the personality traits of non -leaders. The traits of leaders, she contends, are communication

The Microcomputer in the Library: VI. Implementation and Future Development.

ERIC Educational Resources Information Center

Leggate, Peter; Dyer, Hilary

1986-01-01

This sixth article in a series discusses planning for the installation and implementation of automated systems in the library, workstation design and location, scheduling of software implementation, security, data input, staff and reader training, job design, impact of automation on library procedures, evaluation of system performance, and future…

45 CFR 91.47 - Hearings, decisions, post-termination proceedings.

Code of Federal Regulations, 2012 CFR

2012-10-01

... proceedings. Certain HHS procedural provisions applicable to Title VI of the Civil Rights Act of 1964 apply to... 45 Public Welfare 1 2012-10-01 2012-10-01 false Hearings, decisions, post-termination proceedings. 91.47 Section 91.47 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION...

45 CFR 91.47 - Hearings, decisions, post-termination proceedings.

Code of Federal Regulations, 2014 CFR

2014-10-01

... proceedings. Certain HHS procedural provisions applicable to Title VI of the Civil Rights Act of 1964 apply to... 45 Public Welfare 1 2014-10-01 2014-10-01 false Hearings, decisions, post-termination proceedings. 91.47 Section 91.47 Public Welfare Department of Health and Human Services GENERAL ADMINISTRATION...

45 CFR 91.47 - Hearings, decisions, post-termination proceedings.

Code of Federal Regulations, 2013 CFR

2013-10-01

... proceedings. Certain HHS procedural provisions applicable to Title VI of the Civil Rights Act of 1964 apply to... 45 Public Welfare 1 2013-10-01 2013-10-01 false Hearings, decisions, post-termination proceedings. 91.47 Section 91.47 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION...

45 CFR 91.47 - Hearings, decisions, post-termination proceedings.

Code of Federal Regulations, 2011 CFR

2011-10-01

... proceedings. Certain HHS procedural provisions applicable to Title VI of the Civil Rights Act of 1964 apply to... 45 Public Welfare 1 2011-10-01 2011-10-01 false Hearings, decisions, post-termination proceedings. 91.47 Section 91.47 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION...

43 CFR 4.827 - Depositions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Depositions. 4.827 Section 4.827 Public... the Interior-Effectuation of Title VI of the Civil Rights Act of 1964 Procedures § 4.827 Depositions. (a) A party may take the testimony of any person, including a party, by deposition upon oral...

43 CFR 4.827 - Depositions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Depositions. 4.827 Section 4.827 Public... the Interior-Effectuation of Title VI of the Civil Rights Act of 1964 Procedures § 4.827 Depositions. (a) A party may take the testimony of any person, including a party, by deposition upon oral...

32 CFR 231.10 - Financial institutions on DoD installations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... installations shall be provided logistic support as set forth in subpart A of this part. (vi) Military... financial services (to include in-store banking) requiring the outgrant of additional space or logistical... Logistics) (USD(AT&L)) shall monitor policies and procedures governing logistical support furnished to...

32 CFR 231.10 - Financial institutions on DoD installations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... installations shall be provided logistic support as set forth in subpart A of this part. (vi) Military... financial services (to include in-store banking) requiring the outgrant of additional space or logistical... Logistics) (USD(AT&L)) shall monitor policies and procedures governing logistical support furnished to...

32 CFR 231.10 - Financial institutions on DoD installations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... installations shall be provided logistic support as set forth in subpart A of this part. (vi) Military... financial services (to include in-store banking) requiring the outgrant of additional space or logistical... Logistics) (USD(AT&L)) shall monitor policies and procedures governing logistical support furnished to...

42 CFR 431.980 - Eligibility review procedures.

Code of Federal Regulations, 2010 CFR

2010-10-01

... plan during the month under review. (vi) Elements of eligibility in which State policy allows for self-declaration or self-certification are considered to be verified with a self-declaration or self-certification statement. The self-declaration or self-certification must be— (A) Present in the record; (B) Not outdated...

46 CFR 164.019-7 - Non-standard components; acceptance criteria and procedures.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) Inner Envelope Fabric; (iv) Closure (including zippers) or Adjustment Hardware; (v) Body Strap; (vi... in detail and including the unique style, part, or model number, the identification data required by the applicable subpart of this part, and any other manufacturer's identifying data. No two components...

46 CFR 164.019-7 - Non-standard components; acceptance criteria and procedures.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) Inner Envelope Fabric; (iv) Closure (including zippers) or Adjustment Hardware; (v) Body Strap; (vi... in detail and including the unique style, part, or model number, the identification data required by the applicable subpart of this part, and any other manufacturer's identifying data. No two components...

46 CFR 164.019-7 - Non-standard components; acceptance criteria and procedures.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) Inner Envelope Fabric; (iv) Closure (including zippers) or Adjustment Hardware; (v) Body Strap; (vi... in detail and including the unique style, part, or model number, the identification data required by the applicable subpart of this part, and any other manufacturer's identifying data. No two components...

The Effect of Anisotropic Scatter on Atmospheric Neutron Transport

DTIC Science & Technology

2015-03-26

Labratory, ENDF-6 Formats Manual: Data Formats and Procedures for the Evaluated Nuclear Data Files ENDF/B-VI and ENDF/B-VII. BNL - 90365-2009, Revision 2...Upton, NY: BNL , December 2011 [7] Microsoft Visual Studio Professional 2013, Version 12.0.30501.00 Update 2. Computer Software. Microsoft Corporation

45 CFR 1701.2 - Disclosure of records and informational materials.

Code of Federal Regulations, 2010 CFR

2010-10-01

... COMMISSION ON LIBRARIES AND INFORMATION SCIENCE DISCLOSURE OF INFORMATION § 1701.2 Disclosure of records and... and copy any document of the National Commission on Libraries and Information Science. (b) The... procedures, or (vi) endanger the life or physical safety of law enforcement personnel. (8) Contained in or...

32 CFR 204.3 - Policy and procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... information media in the interest of public understanding of the Armed Forces. (v) Armed Forces participation....19. (vi) Records made available to the public, under the Freedom of Information Act, pursuant to 32.... (vii) Services furnished to non-Federal audio-visual media. Fees for such services are governed by the...

32 CFR 204.3 - Policy and procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... information media in the interest of public understanding of the Armed Forces. (v) Armed Forces participation....19. (vi) Records made available to the public, under the Freedom of Information Act, pursuant to 32.... (vii) Services furnished to non-Federal audio-visual media. Fees for such services are governed by the...

32 CFR 204.3 - Policy and procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... information media in the interest of public understanding of the Armed Forces. (v) Armed Forces participation....19. (vi) Records made available to the public, under the Freedom of Information Act, pursuant to 32.... (vii) Services furnished to non-Federal audio-visual media. Fees for such services are governed by the...

32 CFR 204.3 - Policy and procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... information media in the interest of public understanding of the Armed Forces. (v) Armed Forces participation....19. (vi) Records made available to the public, under the Freedom of Information Act, pursuant to 32.... (vii) Services furnished to non-Federal audio-visual media. Fees for such services are governed by the...

45 CFR 1701.2 - Disclosure of records and informational materials.

Code of Federal Regulations, 2014 CFR

2014-10-01

... COMMISSION ON LIBRARIES AND INFORMATION SCIENCE DISCLOSURE OF INFORMATION § 1701.2 Disclosure of records and... and copy any document of the National Commission on Libraries and Information Science. (b) The... procedures, or (vi) endanger the life or physical safety of law enforcement personnel. (8) Contained in or...

45 CFR 1701.2 - Disclosure of records and informational materials.

Code of Federal Regulations, 2011 CFR

2011-10-01

... COMMISSION ON LIBRARIES AND INFORMATION SCIENCE DISCLOSURE OF INFORMATION § 1701.2 Disclosure of records and... and copy any document of the National Commission on Libraries and Information Science. (b) The... procedures, or (vi) endanger the life or physical safety of law enforcement personnel. (8) Contained in or...

45 CFR 1701.2 - Disclosure of records and informational materials.

Code of Federal Regulations, 2013 CFR

2013-10-01

... COMMISSION ON LIBRARIES AND INFORMATION SCIENCE DISCLOSURE OF INFORMATION § 1701.2 Disclosure of records and... and copy any document of the National Commission on Libraries and Information Science. (b) The... procedures, or (vi) endanger the life or physical safety of law enforcement personnel. (8) Contained in or...

45 CFR 1701.2 - Disclosure of records and informational materials.

Code of Federal Regulations, 2012 CFR

2012-10-01

... COMMISSION ON LIBRARIES AND INFORMATION SCIENCE DISCLOSURE OF INFORMATION § 1701.2 Disclosure of records and... and copy any document of the National Commission on Libraries and Information Science. (b) The... procedures, or (vi) endanger the life or physical safety of law enforcement personnel. (8) Contained in or...

43 CFR 4.821 - Motions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... on motions will be at the discretion of the administrative law judge. ... 43 Public Lands: Interior 1 2012-10-01 2011-10-01 true Motions. 4.821 Section 4.821 Public Lands... Interior-Effectuation of Title VI of the Civil Rights Act of 1964 Procedures § 4.821 Motions. Motions and...

43 CFR 4.821 - Motions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... on motions will be at the discretion of the administrative law judge. ... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Motions. 4.821 Section 4.821 Public Lands... Interior-Effectuation of Title VI of the Civil Rights Act of 1964 Procedures § 4.821 Motions. Motions and...

43 CFR 4.821 - Motions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... on motions will be at the discretion of the administrative law judge. ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Motions. 4.821 Section 4.821 Public Lands... Interior-Effectuation of Title VI of the Civil Rights Act of 1964 Procedures § 4.821 Motions. Motions and...

43 CFR 4.821 - Motions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... on motions will be at the discretion of the administrative law judge. ... 43 Public Lands: Interior 1 2013-10-01 2013-10-01 false Motions. 4.821 Section 4.821 Public Lands... Interior-Effectuation of Title VI of the Civil Rights Act of 1964 Procedures § 4.821 Motions. Motions and...

43 CFR 4.821 - Motions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... on motions will be at the discretion of the administrative law judge. ... 43 Public Lands: Interior 1 2014-10-01 2014-10-01 false Motions. 4.821 Section 4.821 Public Lands... Interior-Effectuation of Title VI of the Civil Rights Act of 1964 Procedures § 4.821 Motions. Motions and...

40 CFR 265.56 - Emergency procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... hazardous surface water run-offs from water or chemical agents used to control fire and heat-induced... injuries, if any; and (vi) The possible hazards to human health, or the environment, outside the facility... quantity of material(s) involved; (5) The extent of injuries, if any; (6) An assessment of actual or...

Solid-phase extraction sorbent consisting of alkyltrimethylammonium surfactants immobilized onto strong cation-exchange polystyrene resin.

PubMed

Reid, Kendra R; Kennedy, Lonnie J; Crick, Eric W; Conte, Eric D

2002-10-25

Presented is a solid-phase extraction sorbent material composed of cationic alkyltrimethylammonium surfactants attached to a strong cation-exchange resin via ion-exchange. The original hydrophilic cation-exchange resin is made hydrophobic by covering the surface with alkyl chains from the hydrophobic portion of the surfactant. The sorbent material now has a better ability to extract hydrophobic molecules from aqueous samples. The entire stationary phase (alkyltrimethylammonium surfactant) is removed along with the analyte during the elution step. The elution step requires a mild elution solvent consisting of 0.25 M Mg2+ in a 50% 2-propanol solution. The main advantage of using a removable stationary phase is that traditionally utilized toxic elution solvents such as methylene chloride, which are necessary to efficiently release strongly hydrophobic species from SPE stationary phases, may now be avoided. Also, the final extract is directly compatible with reversed-phase liquid chromatography. The performance of this procedure is presented using pyrene as a test molecule.

Determination of the Degree of Substitution of Cationic Guar Gum by Headspace-Based Gas Chromatography during Its Synthesis.

PubMed

Wan, Xiaofang; Guo, Congbao; Feng, Jiarui; Yu, Teng; Chai, Xin-Sheng; Chen, Guangxue; Xie, Wei-Qi

2017-08-16

This study reports on a headspace-based gas chromatography (HS-GC) technique for determining the degree of substitution (DS) of cationic guar gum during the synthesis process. The method is based on the determination of 2,3-epoxypropyltrimethylammonium chloride in the process medium. After a modest pretreatment procedure, the sample was added to a headspace vial containing bicarbonate solution for measurement of evolved CO 2 by HS-GC. The results showed that the method had a good precision (relative standard deviation of <3.60%) and accuracy for the 2,3-epoxypropyltrimethylammonium chloride measurement, with recoveries in the range of 96-102%, matching with the data obtained by a reference method, and were within 12% of the values obtained by the more arduous Kjeldahl method for the calculated DS of cationic guar gum. The HS-GC method requires only a small volume of sample and, thus, is suitable for determining the DS of cationic guar gum in laboratory-scale process-related applications.

Electronic Absorption Spectra of Mass-Selected Hydrocarbon Cations in Solid Neon: C_nH_4+ (n=5-8,10,12)

NASA Astrophysics Data System (ADS)

Nagy, A.; Fulara, J.; Garkusha, I.; Maier, J. P.

2011-05-01

Small, unsaturated hydrocarbons, C_nH_m (n,m≤6), play an important role in astrochemical models as they have been detected in various space objects such as the interstellar medium or envelopes of carbon-rich stars. Although identification of most of these species was based on rotational studies, they are candidate carriers of the infamous diffuse interstellar bands. It has been proposed that corresponding cationic species formed upon UV radiation may also be of astrophysical relevance; therefore, their optical spectra need to be determined. In this contribution, electronic absorption spectra of mass-selected C_nH_4+ (n=5-8,10,12) ions trapped in neon matrices are presented. The cations were produced in a hot-cathode discharge source, guided through a series of electrostatic lenses, mass filtered and co-deposited with excess of neon onto a rhodium-coated sapphire plate held at 6 K. In the same experiments, neutral species were generated from the cations by a photobleaching procedure.

Statutory Mandates and Agency Enforcement. An Anthology on Procedures and Defenses of P.L. 94-142, Section 504 of the Rehabilitation Act of 1973, Title VI, Title VII of the Civil Rights Act of 1964, Title IX of the Education Amendments of 1972.

ERIC Educational Resources Information Center

National School Boards Association, Washington, DC.

Intended for school district attorneys, administrators, and others responsible for regulation enforcement, the seven articles in this publication concern federal civil rights legislation affecting schools. The substance of the regulations and the procedures employed by regulatory agencies (particularly the Office for Civil Rights) are examined and…

Simultaneous determination of uranium carbide dissolution products by capillary zone electrophoresis.

PubMed

Sladkov, Vladimir; Fourest, Blandine

2009-03-20

Separation and simultaneous determination of a number of organic acid anions (oxalate, mellitate, trimellitate and benzoate) and U(VI) with direct UV detection is developed for analysis of uranium carbide (UC) dissolution products by capillary zone electrophoresis (CZE). Reverse polarity mode is used. It is found that complex formation of U(VI) with carbonate, used as a carrier electrolyte, allows U(VI) to be determined, as negatively charged species, in a single run with organic acid anions. Some parameters such as pH value, composition of electrolyte and detection wavelength are optimized. Under the chosen conditions (carbonate buffer (ionic strength of 100 mM), pH 9.8, 0.15 mM tetradecyltrimethylammonium bromide (TTAB)) a complete separation is achieved. Calibration plots are linear in two ranges of concentration for U(VI) ( approximately 1 x 10(-5) to 1 x 10(-3)), mellitate and trimellitate ( approximately 5 x 10(-6) to 5 x 10(-4)), and about one range ( approximately 1 x 10(-4) to 5 x 10(-3)) for oxalate and benzoate. Accuracy of the procedure is checked by the "added-found" method in standard mixture solutions. Relative standard deviation is within the range of 2-10% and the recovery is in the range of 90-110%. This method is applied for the analysis of real UC dissolution samples.

Chemical trends of the luminescence in wide band gap II 1-xMn xVI semimagnetic semiconductors

NASA Astrophysics Data System (ADS)

Benecke, C.; Busse, W.; Gumlich, H.-E.

1990-04-01

Time resolved emission and excitation spectroscopy is used to investigate the Mn correlated luminescence in wide band gap II-VI compounds, i.e. Zn 1-xMn xS, Cd 1-xMn xSe, Zn 1-xMn xTe and Cd 1-xMn xTe. Additional Information has been obtained with CdxZnyMnzTe( x+ y+ z=1) in checking the luminescence by variation of the ratio of the cations Cd and Zn. Generally speaking, at least two distinct emissions bands can be observed for each II 1- xMn xVI compound. One emissions band is attributed to the internal transition 4T 1(G)→ 6A 1(S) of the 3d 5 electron of the Mn 2+ on regular metal sites with energies of about ≈2 eV. The other emission band is found to occur in the near infrared range of about ≈1.3 eV. This emission band is tentatively interpreted as a transition of Mn 2+ ions on interstitial sites or in small Mn chalcogenide clusters, both interpretations assuming cubic symmetry. This model is supported by the existence of low energy excitation bands and by the great similarity of the shape of the two emission bands which lead to comparable Huang-Rhys factors and effective phonon energies. Also the established trend in the experimental data of the II-VI compounds under consideration confirm this interpretation. For both the IR and the yellow Mn 2+ center, the Racah parameters B and C and the crystal field parameter Dq are determined on the basis of experimental data. As a result, the energy of both the emission and the excitation bands is predominantly determined by the sorrounding anions. These bands shift to higher energies when the anions are changed in the fixed order: Te→Se→S. Regularly, there is also a spectral shift when Zn is replaced by Cd, which is smaller than the shift due to the variation of onions.

Partitioning of uranyl between ferrihydrite and humic substances at acidic and circum-neutral pH

DOE PAGES

Dublet, Gabrielle; Lezama Pacheco, Juan; Bargar, John R.; ...

2017-07-14

As part of a larger study of the reactivity and mobility of uranyl (U(VI)O 2 2+) cations in subsurface environments containing natural organic matter (NOM) and hydrous ferric oxides, we have examined the effect of reference humic and fulvic substances on the sorption of uranyl on 2-line ferrihydrite (Fh), a common, naturally occurring nano-Fe(III)-hydroxide. Uranyl was reacted with Fh at pH 4.6 and 7.0 in the presence and absence of Elliott Soil Humic Acid (ESHA) (0–835 ppm) or Suwanee River Fulvic Acid (SRFA) (0–955 ppm). Here, no evidence was found for reduction of uranyl by either form of NOM aftermore » 24 h of exposure.« less

Partitioning of uranyl between ferrihydrite and humic substances at acidic and circum-neutral pH

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

Dublet, Gabrielle; Lezama Pacheco, Juan; Bargar, John R.

As part of a larger study of the reactivity and mobility of uranyl (U(VI)O 2 2+) cations in subsurface environments containing natural organic matter (NOM) and hydrous ferric oxides, we have examined the effect of reference humic and fulvic substances on the sorption of uranyl on 2-line ferrihydrite (Fh), a common, naturally occurring nano-Fe(III)-hydroxide. Uranyl was reacted with Fh at pH 4.6 and 7.0 in the presence and absence of Elliott Soil Humic Acid (ESHA) (0–835 ppm) or Suwanee River Fulvic Acid (SRFA) (0–955 ppm). Here, no evidence was found for reduction of uranyl by either form of NOM aftermore » 24 h of exposure.« less

Development and Evaluation of a Multiplex Real-Time Polymerase Chain Reaction Procedure to Clinically Type Prevalent Salmonella enterica Serovars

PubMed Central

Muñoz, Nélida; Diaz-Osorio, Miguel; Moreno, Jaime; Sánchez-Jiménez, Miryan; Cardona-Castro, Nora

2010-01-01

A multiplex real-time polymerase chain reaction procedure was developed to identify the most prevalent clinical isolates of Salmonella enterica subsp. enterica. Genes from the rfb, fliC, fljB, and viaB groups that encode the O, H, and Vi antigens were used to design 15 primer pairs and TaqMan probes specific for the genes rfbJ, wzx, fliC, fljB, wcdB, the sdf-l sequence, and invA, which was used as an internal amplification control. The primers and probes were variously combined into six sets. The first round of reactions used two of these sets to detect Salmonella O:4, O:9, O:7, O:8, and O:3,10 serogroups. Once the serogroups were identified, the results of a second round of reactions that used primers and probes for the flagellar antigen l genes, 1,2; e,h; g,m; d; e,n,x; and z10, and the Vi gene were used to identify individual serovars. The procedure was standardized using 18 Salmonella reference strains and other enterobacteria. The procedure's reliability and sensitivity was evaluated using 267 randomly chosen serotyped Salmonella clinical isolates. The procedure had a sensitivity of 95.5% and was 100% specific. Thus, our technique is a quick, sensitive, reliable, and specific means of identifying S. enterica serovars and can be used in conjunction with traditional serotyping. Other primer and probe combinations could be used to increase the number of identifiable serovars. PMID:20110454

Comparative rice seed toxicity tests using filter paper, growth pouch-tm, and seed tray methods

USGS Publications Warehouse

Wang, W.

1993-01-01

Paper substrate, especially circular filter paper placed inside a Petri dish, has long been used for the plant seed toxicity test (PSTT). Although this method is simple and inexpensive, recent evidence indicates that it gives results that are significantly different from those obtained using a method that does not involve paper, especially when testing metal cations. The study compared PSTT using three methods: filter paper, Growth Pouch-TM, and seed tray. The Growth Pouch-TM is a commercially available device. The seed tray is a newly designed plastic receptacle placed inside a Petri dish. The results of the Growth Pouch-TM method showed no toxic effects on rice for Ag up to 40 mg L-1 and Cd up to 20 mg L-1. Using the seed tray method, IC50 (50% inhibitory effect concentration) values were 0.55 and 1.4 mg L-1 for Ag and Cd, respectively. Although results of filter paper and seed tray methods were nearly identical for NaF, Cr(VI), and phenol, the toxicities of cations Ag and Cd were reduced by using the filter paper method; IC50 values were 22 and 18 mg L-1, respectively. The results clearly indicate that paper substrate is not advisable for PSTT.

A Post-synthetic Modification of II–VI Nanoparticles to Create Tb3+ and Eu3+ Luminophores

PubMed Central

Mukherjee, Prasun; Sloan, Robin F.; Shade, Chad M.; Waldeck, David H.; Petoud, Stéphane

2013-01-01

We describe a novel method for creating luminescent lanthanide-containing nanoparticles in which the lanthanide cations are sensitized by the semiconductor nanoparticle’s electronic excitation. In contrast to previous strategies, this new approach creates such materials by addition of external salt to a solution of fully formed nanoparticles. We demonstrate this post-synthetic modification for the lanthanide luminescence sensitization of two visible emitting lanthanides (Ln), Tb3+ and Eu3+ ions, through ZnS nanoparticles in which the cations were added post-synthetically as external Ln(NO3)3·xH2O salt to solutions of ZnS nanoparticles. The post-synthetically treated ZnS nanoparticle systems display Tb3+ and Eu3+ luminescence intensities that are comparable to those of doped Zn(Ln)S nanoparticles, which we reported previously (J. Phys. Chem. A, 2011, 115, 4031–4041). A comparison with the synthetically doped systems is used to contrast the spatial distribution of the lanthanide ions, bulk versus surface localized. The post-synthetic strategy described in this work is fundamentally different from the synthetic incorporation (doping) approach and offers a rapid and less synthetically demanding protocol for Tb3+:ZnS and Eu3+:ZnS luminophores, thereby facilitating their use in a broad range of applications. PMID:23997842

Environmental impact of toxic elements in red mud studied by fractionation and speciation procedures.

PubMed

Milačič, Radmila; Zuliani, Tea; Ščančar, Janez

2012-06-01

Aluminum (Al) is mostly produced from bauxite ore, which contains up to 70% of Al(2)O(3) (alumina). Before alumina is refined to aluminum metal, it is purified by hot alkaline extraction. As a waste by-product red mud is formed. Due to its high alkalinity and large quantities, it represents a severe disposal problem. In Kidričevo (Slovenia), red mud was washed with water before disposal, and after drying, covered with soil. In Ajka (Hungary), the red mud slurry was collected directly in a containment structure, which burst caused a major accident in October 2010. In the present work the environmental impact of toxic elements in red mud from Kidričevo and Ajka were evaluated by applying a sequential extraction procedure and speciation analysis. The predominant red mud fraction was the insoluble residue; nevertheless, environmental concern was focused on the highly mobile water-soluble fraction of Al and Cr. Al in the water-soluble Ajka mud fraction was present exclusively in form of toxic [Al(OH)(4)](-), while Cr existed in its toxic hexavalent form. Comparative assessment to red mud from Kidričevo (Slovenia) with a lower alkalinity (pH 9) with that from Ajka demonstrated significantly lower Al solubility and the presence of only trace amounts of Cr(VI), confirming that disposal of neutralized mud is environmentally much more acceptable and carries a smaller risk of ecological accidents. Since during the Ajka accident huge amounts of biologically available Al and moderate Cr(VI) concentrations were released into the terrestrial and aquatic environments, monitoring of Al and Cr(VI) set free during remedial actions at the contaminated site is essential. Particular care should be taken to minimize the risk of release of soluble Al species and Cr(VI) into water supplies and surface waters. Copyright © 2012 Elsevier B.V. All rights reserved.

78 FR 60755 - Hazardous Materials: Enhanced Enforcement Procedures-Resumption of Transportation

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-02

.... Summary of MAP-21 and Final Rule V. Summary Review of Amendments VI. Regulatory Analyses and Notices A.... Executive Summary On July 6, 2012, the President signed the Moving Ahead for Progress in the 21st Century Act, or the MAP-21, which included the Hazardous Materials Transportation Safety Improvement Act of...

78 FR 51664 - Vessel Traffic Service Updates, Including Establishment of Vessel Traffic Service Requirements...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-21

... requirements. The changes made by this rule will align regulations with the current operating procedures of the... History V. Discussion of Comments and Changes VI. Regulatory Analyses A. Regulatory Planning and Review B... Waterways Safety System PWSA Ports and Waterways Safety Act SOLAS International Convention for the Safety of...

42 CFR 430.2 - Other applicable Federal regulations.

Code of Federal Regulations, 2014 CFR

2014-10-01

...: Effectuation of Title VI of the Civil Rights Act of 1964. Part 81—Practice and Procedure for Hearings Under 45... 42 Public Health 4 2014-10-01 2014-10-01 false Other applicable Federal regulations. 430.2 Section 430.2 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

Estimated Effects of Retirement Revision on Retention of Navy Tactical Pilots.

DTIC Science & Technology

1986-12-01

detailed explanation of the procedure and proofs can be found in Hanushek and Jackson [Ref. 441. S511 ,V. 󈧈 VI. RESULTS AND ANALYSIS A. DESCRIPTIVE...Introduction to Econometrics, pp. 242-243, Prentice-Hall, 1978. 44. Hanushek Eric ard Jackson, John, Statistical .Mlethods for Social Scientists, p. S188

Justice. Law in a Free Society Series. Level VI. Second Edition.

ERIC Educational Resources Information Center

Center for Civic Education, Calabasas, CA.

Designed to help high school students, this curriculum guides youngsters to develop a better understanding of difficult issues raised by questions of justice. It is hoped that the ideas, observations, questions, and procedures students learn in the curriculum will help them to make informed decisions about how to promote justice and combat…

Some More Microscale Gas Experiments

ERIC Educational Resources Information Center

Worley, Bob

2011-01-01

In 1984, a teacher was successfully prosecuted by the Health and Safety Executive. The case centred around chemically prepared hydrogen that was dried by bubbling it through concentrated sulfuric(VI) acid and then passed over hot copper(II) oxide. The procedure was often carried out quantitatively to find the mass of copper in a sample of…

26 CFR 1.468B-3 - Rules applicable to the transferor.

Code of Federal Regulations, 2010 CFR

2010-04-01

...(a). In computing the gain or loss, the amount realized by the transferor is the fair market value of... transfer to the qualified settlement fund; (iii) The appraised fair market value of the property on the... explanation of the procedure employed; (vi) The terms of any agreement or understanding entered into (or...

40 CFR 267.56 - What are the required emergency procedures for the emergency coordinator?

Code of Federal Regulations, 2013 CFR

2013-07-01

..., and, if necessary, by chemical analysis. (2) Assess possible hazards to human health or the... explosion which could threaten human health, or the environment, outside the facility, he must report his...) The extent of injuries, if any. (vi) The possible hazards to human health or the environment outside...

30 CFR 251.14 - Protecting and disclosing data and information submitted to MMS under a permit.

Code of Federal Regulations, 2010 CFR

2010-07-01

... lands during drilling operations, the Regional Director will immediately issue a public announcement... position. (b) Timetable for release of G&G data and information related to oil, gas, and sulphur that MMS... environment; (vi) Make field determinations; or (vii) Determine eligibility for royalty relief. (c) Procedure...

40 CFR 53.43 - Test procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... of the test section of the wind tunnel. The mean wind speed in the test section must be within ±10... wind tunnel and allow the particle concentration to stabilize. (vi) Install an array of five or more evenly spaced isokinetic samplers in the sampling zone (see § 53.42(d)) of the wind tunnel. Collect...

40 CFR 53.43 - Test procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

...-sectional area of the test section of the wind tunnel. The mean wind speed in the test section must be... into the wind tunnel and allow the particle concentration to stabilize. (vi) Install an array of five or more evenly spaced isokinetic samplers in the sampling zone (see § 53.42(d)) of the wind tunnel...

40 CFR 53.43 - Test procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-sectional area of the test section of the wind tunnel. The mean wind speed in the test section must be... into the wind tunnel and allow the particle concentration to stabilize. (vi) Install an array of five or more evenly spaced isokinetic samplers in the sampling zone (see § 53.42(d)) of the wind tunnel...

Design, Fabrication, Processing, and Testing of Micro-Electro-Mechanical Chemical Sensors

DTIC Science & Technology

1995-12-01

sensor ...... .......................... 118 71. Resonating bridge parameter curves ...... ......................... 119 72. Low frequency oscillations...131 82. Heater V-I curve .. .. .. .. ... ... ... ... ... ... ... ... ..... 132 83. Frequency response of heated chemoresistor...devices, including devices that may be pre-stressed due to fabrication procedures (i.e. curve out of the plane after being released)? Due to their

46 CFR 197.565 - Notifying personnel of benzene hazards.

Code of Federal Regulations, 2010 CFR

2010-10-01

... personal protective equipment in emergency situations; (vi) The meaning of a regulated area and the means..., control measures such as personal protection equipment, and first aid procedures for benzene. A copy of... to benzene; (iv) The measures that may be taken and the equipment that may be used to protect persons...

46 CFR 197.565 - Notifying personnel of benzene hazards.

Code of Federal Regulations, 2011 CFR

2011-10-01

... personal protective equipment in emergency situations; (vi) The meaning of a regulated area and the means..., control measures such as personal protection equipment, and first aid procedures for benzene. A copy of... to benzene; (iv) The measures that may be taken and the equipment that may be used to protect persons...

42 CFR 52c.7 - Other HHS regulations that apply.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 401—Rights to inventions made by nonprofit organizations and small business firms under government... Effectuation of Title VI of the Civil Rights Act of 1964 45 CFR part 81—Practice and procedure for hearings... Animals,” Office for Protection from Research Risks, NIH (Revised September 1986), or successor [58 FR...

42 CFR 63.10 - Other HHS regulations and policies that apply.

Code of Federal Regulations, 2014 CFR

2014-10-01

...—effectuation of title VI of the Civil Rights Act of 1964. 45 CFR part 81—Practice and procedure for hearings... Laboratory Animals” (Revised September 1986), Office of Laboratory Animal Welfare, NIH. (Note: Interested persons should contact the Office of Laboratory Animal Welfare, NIH, Rockledge Building I, 6705 Rockledge...

42 CFR 52c.7 - Other HHS regulations that apply.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 401—Rights to inventions made by nonprofit organizations and small business firms under government... Effectuation of Title VI of the Civil Rights Act of 1964 45 CFR part 81—Practice and procedure for hearings... Animals,” Office for Protection from Research Risks, NIH (Revised September 1986), or successor [58 FR...

42 CFR 63.10 - Other HHS regulations and policies that apply.

Code of Federal Regulations, 2011 CFR

2011-10-01

...—effectuation of title VI of the Civil Rights Act of 1964. 45 CFR part 81—Practice and procedure for hearings... Laboratory Animals” (Revised September 1986), Office of Laboratory Animal Welfare, NIH. (Note: Interested persons should contact the Office of Laboratory Animal Welfare, NIH, Rockledge Building I, 6705 Rockledge...

42 CFR 63.10 - Other HHS regulations and policies that apply.

Code of Federal Regulations, 2012 CFR

2012-10-01

...—effectuation of title VI of the Civil Rights Act of 1964. 45 CFR part 81—Practice and procedure for hearings... Laboratory Animals” (Revised September 1986), Office of Laboratory Animal Welfare, NIH. (Note: Interested persons should contact the Office of Laboratory Animal Welfare, NIH, Rockledge Building I, 6705 Rockledge...

42 CFR 63.10 - Other HHS regulations and policies that apply.

Code of Federal Regulations, 2013 CFR

2013-10-01

...—effectuation of title VI of the Civil Rights Act of 1964. 45 CFR part 81—Practice and procedure for hearings... Laboratory Animals” (Revised September 1986), Office of Laboratory Animal Welfare, NIH. (Note: Interested persons should contact the Office of Laboratory Animal Welfare, NIH, Rockledge Building I, 6705 Rockledge...

In situ remediation of hexavalent chromium contaminated soil by CMC-stabilized nanoscale zero-valent iron composited with biochar.

PubMed

Zhang, Runyuan; Zhang, Nuanqin; Fang, Zhanqiang

2018-03-01

In this study, the remediation experiments were performed outdoors in natural conditions. Carboxymethyl cellulose (CMC)-stabilized nanoscale zero-valent iron (CMC-nZVI), biochar (BC) and CMC-stabilized nanoscale zero-valent iron composited with biochar (CMC-nZVI/BC) were synthesized and investigated for their effect on the in situ remediation of hexavalent chromium [Cr(VI)] contaminated soil and the concentration of available iron was tested after the remediation, compared with the untreated soil. The results of toxicity characteristic leaching procedure (TCLP) test showed that CMC-nZVI and CMC-nZVI/BC used as remediation materials could obviously improve the remediation rate of Cr contaminated soil and when the ratio of CMC-nZVI to Fe 0 was 2.5 g/Kg, the leachability of Cr(VI) and Cr total can be reduced by 100% and 95.8% simultaneously. Moreover, sequential extraction procedure (SEP) showed that most exchangeable Cr converted to carbonate-bound and Fe-Mn oxides-bound, reducing the availability and leachability of Cr in the soil.

Transuranic Hybrid Materials: Crystallographic and Computational Metrics of Supramolecular Assembly

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

Surbella, Robert G.; Ducati, Lucas C.; Pellegrini, Kristi L.

A family of twelve supramolecular [AnO2Cl4]2- (An = U, Np, Pu) containing compounds assembled via hydrogen and halogen bonds donated by substituted 4-X-pyridinium cations (X = H, Cl, Br, I) is reported. These materials were prepared from a room-temperature synthesis wherein crystallization of unhydrolyzed and valence pure [An(VI)O2Cl4]2- (An = U, Np, Pu) tectons are the norm. We present a hierarchy of assembly criteria based on crystallographic observations, and subsequently quantify the strengths of the non-covalent interactions using Kohn-Sham density functional calculations. We provide, for the first time, a detailed description of the electrostatic potentials (ESPs) of the actinyl tetrahalidemore » dianions and reconcile crystallographically observed structural motifs and non-covalent interaction (NCI) acceptor-donor pairings. Our findings indicate that the average electrostatic potential across the halogen ligands (the acceptors) changes by only ~2 kJ mol-1 across the AnO22+ series, indicating the magnitude of the potential is independent of the metal center. The role of the cation is therefore critical in directing structural motifs and dictating the resulting hydrogen and halogen bond strengths, the former being stronger due to the positive charge centralized on the pyridyl nitrogen N-H+. Subsequent analyses using the Quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) approaches support this conclusion and highlight the structure directing role of the cations. Whereas one can infer that the 2 Columbic attraction is the driver for assembly, the contribution of the non-covalent interaction is to direct the molecular-level arrangement (or disposition) of the tectons.« less

Actinobacteria consortium as an efficient biotechnological tool for mixed polluted soil reclamation: Experimental factorial design for bioremediation process optimization.

PubMed

Aparicio, Juan Daniel; Raimondo, Enzo Emanuel; Gil, Raúl Andrés; Benimeli, Claudia Susana; Polti, Marta Alejandra

2018-01-15

The objective of the present work was to establish optimal biological and physicochemical parameters in order to remove simultaneously lindane and Cr(VI) at high and/or low pollutants concentrations from the soil by an actinobacteria consortium formed by Streptomyces sp. M7, MC1, A5, and Amycolatopsis tucumanensis AB0. Also, the final aim was to treat real soils contaminated with Cr(VI) and/or lindane from the Northwest of Argentina employing the optimal biological and physicochemical conditions. In this sense, after determining the optimal inoculum concentration (2gkg -1 ), an experimental design model with four factors (temperature, moisture, initial concentration of Cr(VI) and lindane) was employed for predicting the system behavior during bioremediation process. According to response optimizer, the optimal moisture level was 30% for all bioremediation processes. However, the optimal temperature was different for each situation: for low initial concentrations of both pollutants, the optimal temperature was 25°C; for low initial concentrations of Cr(VI) and high initial concentrations of lindane, the optimal temperature was 30°C; and for high initial concentrations of Cr(VI), the optimal temperature was 35°C. In order to confirm the model adequacy and the validity of the optimization procedure, experiments were performed in six real contaminated soils samples. The defined actinobacteria consortium reduced the contaminants concentrations in five of the six samples, by working at laboratory scale and employing the optimal conditions obtained through the factorial design. Copyright © 2017 Elsevier B.V. All rights reserved.

Choice with frequently changing food rates and food ratios.

PubMed

Baum, William M; Davison, Michael

2014-03-01

In studies of operant choice, when one schedule of a concurrent pair is varied while the other is held constant, the constancy of the constant schedule may exert discriminative control over performance. In our earlier experiments, schedules varied reciprocally across components within sessions, so that while food ratio varied food rate remained constant. In the present experiment, we held one variable-interval (VI) schedule constant while varying the concurrent VI schedule within sessions. We studied five conditions, each with a different constant left VI schedule. On the right key, seven different VI schedules were presented in seven different unsignaled components. We analyzed performances at several different time scales. At the longest time scale, across conditions, behavior ratios varied with food ratios as would be expected from the generalized matching law. At shorter time scales, effects due to holding the left VI constant became more and more apparent, the shorter the time scale. In choice relations across components, preference for the left key leveled off as the right key became leaner. Interfood choice approximated strict matching for the varied right key, whereas interfood choice hardly varied at all for the constant left key. At the shortest time scale, visit patterns differed for the left and right keys. Much evidence indicated the development of a fix-and-sample pattern. In sum, the procedural difference made a large difference to performance, except for choice at the longest time scale and the fix-and-sample pattern at the shortest time scale. © Society for the Experimental Analysis of Behavior.

Electrochemical oxidation of 243Am(III) in nitric acid by a terpyridyl-derivatized electrode

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

Dares, C. J.; Lapides, A. M.; Mincher, B. J.

A high surface area, tin-doped indium oxide electrode surface-derivatized with a terpyridine ligand has been applied to the oxidation of trivalent americium to Am(V) and Am(VI) in nitric acid. Potentials as low as 1.8 V vs. the saturated calomel electrode are used, 0.7 V lower than the 2.6 V potential for one-electron oxidation of Am(III) to Am(IV) in 1 M acid. This simple electrochemical procedure provides, for the first time, a method for accessing the higher oxidation states of Am in non-complexing media for developing the coordination chemistries of Am(V) and Am(VI) and, more importantly, for separation of americium frommore » nuclear waste streams.« less

The group separation of the rare-earth elements and yttrium from geologic materials by cation-exchange chromatography

USGS Publications Warehouse

Crock, J.G.; Lichte, F.E.; Wildeman, T.R.

1984-01-01

Demand is increasing for the determination of the rare-earth elements (REE) and yttrium in geologic materials. Due to their low natural abundance in many materials and the interferences that occur in many methods of determination, a separation procedure utilizing gradient strong-acid cation-exchange chromatography is often used to preconcentrate and isolate these elements from the host-rock matrix. Two separate gradient strong-acid cation-exchange procedures were characterized and the major elements as well as those elements thought to provide the greatest interference for the determination of the REE in geologic materials were tested for separation from the REE. Simultaneous inductively coupled argon plasma-atomic emission spectroscopy (ICAP-AES) measurements were used to construct the chromatograms for the elution studies, allowing the elution patterns of all the elements of interest to be determined in a single fraction of eluent. As a rock matrix, U.S. Geological Survey standard reference BCR-1 basalt was digested using both an acid decomposition procedure and a lithium metaborate fusion. Hydrochloric and nitric acids were tested as eluents and chromatograms were plotted using the ICAP-AES data; and we observed substantial differences in the elution patterns of the REE and as well as in the solution patterns of Ba, Ca, Fe and Sr. The nitric acid elution required substantially less eluent to elute the REE and Y as a group when compared to the hydrochloric acid elution, and provided a clearer separation of the REE from interfering and matrix elements. ?? 1984.

Microscale Procedure for Inorganic Qualitative Analysis with Emphasis on Writing Equations: Chemical Fingerprinting Applied to the "n"-bottle Problem of Matching Samples with Their Formulas

ERIC Educational Resources Information Center

Sattsangi, Prem D.

2014-01-01

A laboratory method for teaching inorganic qualitative analysis and chemical equations is described. The experiment has been designed to focus attention on cations and anions that react to form products. This leads to a logical approach to understand and write chemical equations. The procedure uses 3 mL plastic micropipettes to store and deliver…

Speciation of chromium using reversed phase-high performance liquid chromatography coupled to different spectrometric detection methods

NASA Astrophysics Data System (ADS)

Andrle, C. M.; Jakubowski, N.; Broekaert, J. A. C.

1997-02-01

Speciation of Cr(III) and Cr(VI) based on the formation of different complexes with ammonium-pyrrolidinedithioate (APDC) in a continuous flow technique and their preconcentration using solid phase extraction (SPE) have been elaborated and applied to the analysis of waste waters from the galvanic industry. The Cr complexes were separated and determined using reversed phase-high performance liquid chromatography (RP-HPLC) coupled to different detection methods, namely UV-detection, graphite furnace-atomic absorption spectrometry (GF-AAS) and inductively coupled plasma mass spectrometry with hydraulic high pressure nebulization (HHPN/ICP-MS). After optimization the detection limits for Cr(III) and Cr(VI) of all methods are at the μg 1 -1 level and the precision in terms of RSD is 5% ( cCr = 100 μg 1 -1, N = 10). The procedure was applied to the determination of Cr(III) and Cr(VI) at the μg 1 -1 level in galvanic waste waters, and its accuracy was approved by comparing the results with those of independent methods.

CaCO3-III and CaCO3-VI, high-pressure polymorphs of calcite: Possible host structures for carbon in the Earth's mantle

NASA Astrophysics Data System (ADS)

Merlini, M.; Hanfland, M.; Crichton, W. A.

2012-06-01

Calcite, CaCO3, undergoes several high pressure phase transitions. We report here the crystal structure determination of the CaCO3-III and CaCO3-VI high-pressure polymorphs obtained by single-crystal synchrotron X-ray diffraction. This new technical development at synchrotron beamlines currently affords the possibility of collecting single-crystal data suitable for structure determination in-situ at non-ambient conditions, even after multiphase transitions. CaCO3-III, observed in the pressure range 2.5-15 GPa, is triclinic, and it presents two closely related structural modifications, one, CaCO3-III, with 50 atoms in the unit cell [a=6.281(1) Å, b=7.507(2) Å, c=12.516(3) Å, α=93.76(2)°, β=98.95(2)°, γ=106.49(2)°, V=555.26(20) Å3 at 2.8 GPa], the second, CaCO3-IIIb, with 20 atoms [a=6.144(3) Å, b=6.3715(14) Å, c=6.3759(15) Å, α= 93.84(2)°, β=107.34(3)°, γ=107.16(3)°, V=224.33(13) Å3 at 3.1 GPa]. Different pressure-time experimental paths can stabilise one or the other polymorph. Both structures are characterised by the presence of non-coplanar CO3 groups. The densities of CaCO3-III (2.99 g/cm3 at 2.8 GPa) and CaCO3-IIIb (2.96 g/cm3 at 3.1 GPa) are lower than aragonite, in agreement with the currently accepted view of aragonite as the thermodynamically stable Ca-carbonate phase at these pressures. The presence of different cation sites, with variable volume and coordination number (7-9), suggests however that these structures have the potential to accommodate cations with different sizes without introducing major structural strain. Indeed, this structure can be adopted by natural Ca-rich carbonates, which often exhibit compositions deviating from pure calcite. Mg-calcites are found both in nature (Frezzotti et al., 2011) and in experimental syntheses at conditions corresponding to deep subduction environments (Poli et al., 2009). At these conditions, the low pressure rhombohedral calcite structure is most unlikely to be stable, and, at the same time, Mg and Fe solubility in aragonite is hindered energetically in the 9-fold coordination site. Above 15 GPa, and up to the maximum pressure investigated (40 GPa), we observe the high-pressure polymorph CaCO3-VI, triclinic [a=3.3187(12) Å, b=4.8828(14) Å, c=5.5904(14) Å, α=103.30(2)°, β=94.73(2)°, γ=89.21(2)°, V=87.86(20) Å3 at 30.4 GPa] with 10 atoms in the unit cell. It is characterised by coplanar CO3 groups but the structure is no longer layered, as in the lower pressure polymorphs. The density of the CaCO3-VI structure (3.78 g/cm3 at 30.4 GPa) is higher than aragonite. For this reason it could be supposed that a region may exist where this polymorph replaces aragonite in the Earth's intermediate mantle. The lower coordination number for the Ca site [7+2] instead of [9] in aragonite suggests that this structure could be easily adopted by an extended solid-solution range from calcite towards the dolomite [CaMg(CO3)2]-ankerite [CaFe(CO3)2] compositional join. The transitions from calcite to CaCO3-III, CaCO3-IIIb and CaCO3-VI are perfectly reversible and after pressure release we always observe the calcite structure, with the sample recovered as a single-crystal. Indeed, it is highly unlikely that these structures can be observed in samples recovered from high-pressure environments.

Complexes of oxovanadium(IV), dioxovanadium(V) and dioxouranium(VI) with aminoacids in aqueous solution

NASA Astrophysics Data System (ADS)

Lagrange, P.; Schneider, M.; Lagrange, J.

1998-11-01

The equilibria between three oxocations (VO2+, VO2+ and UO22+) and several ?- aminoacids (glycine, serine, asparagine, lysine, aspartic acid and glutamic acid) are studied in aqueous solution. Stoichiometry and stability of the complexes formed are determined from a combination of potentiometric and spectroscopic measurements. Solution structures of the different complexes are proposed based on the thermodynamic results. The oxovanadium(IV) complexes appear less stable than the corresponding dioxouranium(VI) and dioxovanadium(V) complexes. VO2+ can be bound to only one ligand to form monodentate or chelate complexes. UO22+ and VO2+ cations may be chelated by one or two ligands. Les équilibres entre trois oxocations, VO2+, VO2+ et UO22+ et plusieurs α-aminoacides, glycine, sérine, asparagine, lysine et acides aspartique et glutamique, sont étudiés en solution aqueuse par potentiométrie couplée à la spectrophotométrie. Les complexes de VO2+ sont moins stables que les complexes de VO2+ et UO22+ de même stoechiométrie. VO2+ ne peut se lier qu'à un seul ligand pour former soit des complexes monodentés, soit des chélates. UO22+ et VO2+ peuvent être chélatés par un ou deux ligands. Des structures hypothétiques en solution sont proposées.

Application of Brazilian kaolinite clay as adsorbent to removal of U(VI) from aqueous solution: Kinetic and thermodynamic of cation-basic interactions

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

Guerra, Denis L., E-mail: denis@cpd.ufmt.b; Leidens, Victor L.; Viana, Rubia R.

2010-05-15

The compound N{sup 1}-[3-(trimethoxysilyl)propyl]diethylenetriamine was anchored onto Amazon kaolinite surface by heterogeneous route. The modified and natural kaolinite samples were characterized by transmission electron microscopy, scanning electron microscopic, X-ray diffraction, and nuclear magnetic nuclei of {sup 29}Si and {sup 13}C. The well-defined peaks obtained in the {sup 13}C NMR spectrum in the 5.0-62.1 ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The ability of these materials to remove U(VI) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 4.0.more » The kinetic parameters analyzed by the Lagergren and Elovich models gave a good fit for a pseudo-second order reaction with k{sub 2} values 16.0 and 25.1 mmol g{sup -1} min{sup -1} ranges for natural and modified kaolinite clays, respectively. The energetic effects caused by metal ion adsorption were determined through calorimetric titrations. - Graphical abstract: This investigation reports the use of original and modified kaolinites as alternative absorbents. The compound N-[3-trimethoxysilyl)propyl]diethylenetriamine was anchored onto Amazon kaolinite surface by heterogeneous route.« less

XAS study of chromium in Li 2MSiO 4 (M=Mg, Zn)

NASA Astrophysics Data System (ADS)

Jousseaume, C.; Ribot, F.; Kahn-Harari, A.; Vivien, D.; Villain, F.

2003-01-01

X-ray absorption spectroscopy (XAS) investigations at the Cr K-edge on Cr:Li 2MSiO 4 (M=Mg, Zn) have been performed to understand the exceptionally long fluorescence lifetime of Cr IV. Previous work has shown the simultaneous presence of three oxidation states Cr IV, Cr V and Cr VI. X-ray absorption near edge structure measurements confirm that Cr in Li 2MSiO 4 (M=Mg, Zn) single crystals is in tetrahedral coordination. They also reveal that Cr VI is the dominant species in Li 2MgSiO 4, and that Li 2ZnSiO 4 contains more Cr V than Li 2MgSiO 4. The extended X-ray absorption fine structure spectra of Cr:Li 2MgSiO 4 single crystals recorded at the Cr K-edge, are fitted with two types of Cr environments: the first one corresponds to oxygen atoms at a mean distance of 1.68 Å and the second to oxygen atoms at a mean distance of 2.07 Å. This second environment is attributed to Cr III in the minor parasitic phase LiCr IIIO 2. The first environment corresponds to Cr that substitutes silicon in the Li 2MgSiO 4 lattice in the silicon site if the cations sizes are considered.

Effects of atmospheric ageing under different temperatures on surface properties of sludge-derived biochar and metal/metalloid stabilization.

PubMed

Wang, Hong; Feng, Mingyu; Zhou, Fengsa; Huang, Xinchen; Tsang, Daniel C W; Zhang, Weihua

2017-10-01

Ageing is a common phenomenon during biochar storage and its soil application. In this study, we exposed sludge-derived biochar (SDBC) in the air under 4 °C, 22 °C, and 45 °C for 30-120 d to imitate the ageing process after SDBC production. The aged SDBC was characterized and its sorption capacities for Pb(II), Cr(V) and As(III) were compared with the fresh ones in batch sorption experiments. The results showed an increase in acidity, cation exchange capacity, and carboxyl groups of SDBC surface, but a decrease in alkalinity and Fe(III) species during ageing, indicating the oxidation. In addition, ageing for more than 30 d was found to favor the Pb(II) and As(III) sorption, because of higher density of available oxygen-containing groups. The Cr(VI) sorption was found to be compromised by the ageing, because some reducing agents for Cr(VI) reduction was consumed there. Higher temperatures accelerated the above-mentioned ageing effect. Yet, when the SDBC was applied in the heavy-metal contaminated soil, its performance would be affected by both ageing of SDBC itself as well as long-term interactions among soil components, such as colloids and solution, heavy metals, and SDBC, which require further investigation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Speciation of selenium in environmental samples by solid-phase spectrophotometry using 2,3-dichloro-6-(2,7-dihydroxy-naphthylazo)quinoxaline.

PubMed

Amin, Alaa S

2014-01-01

Solid-phase spectrophotometry was applied to determination of trace amounts of selenium (Se) in water, soil, plant materials, human hair, and a cosmetic preparation (lipstick). Se(IV) was sorbed in a dextran type lipophilic gel as a complex with 2,3-dichloro-6-(2,7-dihydroxy-naphthylazo)quinoxaline (DCDHNAQ), whereas Se(VI) was determined after boiling in HCI for 10 min to convert Se(VI) to Se(IV). Resin phase absorbances at 588 and 800 nm were measured directly, which allowed the determination of Se in the range of 0.2-3.3 microg/L with an RSD of 1.22%. The influences of analytical parameters including pH of the aqueous solution, amounts of DCDHNAQ, and sample volume were investigated. The molar absorptivities were found to be 1.09 x 10(6), 4.60 x 10(6), and 1.23 x 10(7) L/mol cm for 100, 500, and 1000 mL, respectively. The LOD and LOQ of the 500 mL sample method were 110 and 360 ng/L, respectively, when using 50 mg dextran type lipophilic gel. For a 1000 mL sample, the LOD and LOQ were 60 and 200 ng/L, respectively, using 50 mg of the exchanger. Increasing the sample volume enhanced the sensitivity. No considerable interferences were observed from other investigated anions and cations on the Se determination.

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

Mehta, Vrajesh; Maillot, Fabien; Wang, Zheming

Uranyl phosphate solids are often found with uranium ores, and their low solubility makes them promising target phases for in situ remediation of uranium-contaminated subsurface environments. The products and solubility of uranium(VI) precipitated with phosphate can be affected by the pH, dissolved inorganic carbon (DIC) concentration, and co-solute composition (e.g. Na+/Ca2+) of the groundwater. Batch experiments were performed to study the effect of these parameters on the products and extent of uranium precipitation induced by phosphate addition. In the absence of co-solute cations, chernikovite [H3O(UO2)(PO4)•3H2O] precipitated despite uranyl orthophosphate [(UO2)3(PO4)2•4H2O] being thermodynamically more favorable under certain conditions. As determined usingmore » X-ray diffraction, electron microscopy, and laser induced fluorescence spectroscopy, the presence of Na+ or Ca2+ as a co-solute led to the precipitation of sodium autunite ([Na2(UO2)2(PO4)2] and autunite [Ca(UO2)2(PO4)2]), which are structurally similar to chernikovite. In the presence of sodium, the dissolved U(VI) concentrations were generally in agreement with equilibrium predictions of sodium autunite solubility. However, in the calcium-containing systems, the observed concentrations were below the predicted solubility of autunite, suggesting the possibility of uranium adsorption to or incorporation in a calcium phosphate precipitate in addition to the precipitation of autunite.« less

The role of metal ions in chemical evolution - Polymerization of alanine and glycine in a cation-exchanged clay environment

NASA Technical Reports Server (NTRS)

Lawless, J. G.; Levi, N.

1979-01-01

The effect of the exchangeable cation on the condensation of glycine and alanine was investigated using a series of homoionic bentonites. A cycling procedure of drying, warming and wetting was employed. Peptide bond formation was observed, and the effectiveness of metal ions to catalyze the condensation was Cu(2+) greater than Ni(2) approximately equals Zn(2+) greater than Na(+). Glycine showed 6% of the monomer incorporated into oligomers with the largest detected being the pentamer. Alanine showed less peptide bond formation (a maximum of 2%) and only the dimer was observed.

A new titanium-bearing calcium aluminosilicate phase. 2: Crystallography and crystal chemistry of grains formed in slowly cooled melts with bulk compositions of calcium-aluminium-rich inclusions

NASA Technical Reports Server (NTRS)

Barber, David J.; Beckett, John R.; Paque, Julie M.; Stolper, Edward

1994-01-01

The crystallography and crystal chemistry of a new calcium- titanium-aluminosilicate mineral (UNK) observed in synthetic analogs to calcium-aluminum-rich inclusions (CAIs) from carbonaceous chondrites was studied by electron diffraction techniques. The unit cell is primitive hexagonal or trigonal, with a = 0.790 +/- 0.02 nm and c = 0.492 +/- 0.002 nm, similar to the lattice parameters of melilite and consistent with cell dimensions for crystals in a mixer furnace slag described by Barber and Agrell (1994). The phase frequently displays an epitactic relationship in which melilite acts as the host, with (0001)(sub UNK) parallel (001)(sub mel) and zone axis group 1 0 -1 0(sub UNK) parallel zone axis group 1 0 0(sub mel). If one of the two space groups determined by Barber and Agrell (1994) for their sample of UNK is applicable (P3m1 or P31m), then the structure is probably characterized by puckered sheets of octahedra and tetrahedra perpendicular to the c-axis with successive sheets coordinated by planar arrays of Ca. In this likely structure, each unit cell contains three Ca sites located in mirror planes, one octahedrally coordinated cation located along a three-fold axis and five tetrahedrally coordinated cations, three in mirrors and two along triads. The octahedron contains Ti but, because there are 1.3-1.9 cations of Ti/formula unit, some of the Ti must also be in tetrahedral coordination, an unusual but not unprecedented situation for a silicate. Tetrahedral sites in mirror planes would contain mostly Si, with lesser amounts of Al while those along the triads correspondingly contain mostly Al with subordinate Ti. The structural formula, therefore, can be expressed as Ca(sub 3)(sup VIII)(Ti,Al)(sup VI)(Al,Ti,Si)(sub 2)(sup IV)(Si,Al)(sub 3)(sup IV)O14 with Si + Ti = 4. Compositions of meteoritic and synthetic Ti-bearing samples of the phase can be described in terms of a binary solid solution between the end-members Ca3TiAl2Si3O14 and Ca3Ti(AlTi)(AlSi2)O14. A Ti-free analog with a formula of Ca3Al2Si4O14 synthesized by Paque et al. (1994) is thought to be related structurally but with the octahedral site being occupied by Al, that is, Ca(sub 3)(sup VIII)Al(sup VI)(Al,Si)(sub 2)(sup IV)(Si)(sub 3)(sup IV)O14.

Hexavalent chromium exposures during full-aircraft corrosion control.

PubMed

Carlton, Gary N

2003-01-01

Aluminum alloys used in the construction of modern aircraft are subject to corrosion. The principal means of controlling this corrosion in the U.S. Air Force are organic coatings. The organic coating system consists of a chromate conversion coat, epoxy resin primer, and polyurethane enamel topcoat. Hexavalent chromium (CrVI) is present in the conversion coat in the form of chromic acid and in the primer in the form of strontium chromate. CrVI inhalation exposures can occur when workers spray conversion coat onto bare metal and apply primer to the treated metal surface. In addition, mechanical abrasion of aircraft surfaces can generate particulates that contain chromates from previously applied primers and conversion coats. This study measured CrVI exposures during these corrosion control procedures. Mean time-weighted average (TWA) exposure to chromic acid during conversion coat treatment was 0.48 microg/m(3), below the current American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV(R)) TWA of 50 microg/m(3) for water-soluble CrVI compounds. Mean TWA exposures to strontium chromate were 5.33 microg/m(3) during mechanical abrasion and 83.8 microg/m(3) during primer application. These levels are in excess of the current ACGIH TLV-TWA of 0.5 microg/m(3) for strontium chromate. In the absence of a change from chromated to nonchromated conversion coats and primers, additional control measures are needed to reduce these exposures.

Li0.5Al0.5Mg2(MoO4)3

PubMed Central

Ennajeh, Ines; Zid, Mohamed Faouzi; Driss, Ahmed

2013-01-01

The title compound, lithium/aluminium dimagnesium tetra­kis­[orthomolybdate(VI)], was prepared by a solid-state reaction route. The crystal structure is built up from MgO6 octa­hedra and MoO4 tetra­hedra sharing corners and edges, forming two types of chains running along [100]. These chains are linked into layers parallel to (010) and finally linked by MoO4 tetra­hedra into a three-dimensional framework structure with channels parallel to [001] in which lithium and aluminium cations equally occupy the same position within a distorted trigonal–bipyramidal coordination environment. The title structure is isotypic with LiMgIn(MoO4)3, with the In site becoming an Mg site and the fully occupied Li site a statistically occupied Li/Al site in the title structure. PMID:24426975

Dynamic probe of ZnTe(110) surface by scanning tunneling microscopy

PubMed Central

Kanazawa, Ken; Yoshida, Shoji; Shigekawa, Hidemi; Kuroda, Shinji

2015-01-01

The reconstructed surface structure of the II–VI semiconductor ZnTe (110), which is a promising material in the research field of semiconductor spintronics, was studied by scanning tunneling microscopy/spectroscopy (STM/STS). First, the surface states formed by reconstruction by the charge transfer of dangling bond electrons from cationic Zn to anionic Te atoms, which are similar to those of IV and III–V semiconductors, were confirmed in real space. Secondly, oscillation in tunneling current between binary states, which is considered to reflect a conformational change in the topmost Zn–Te structure between the reconstructed and bulk-like ideal structures, was directly observed by STM. Third, using the technique of charge injection, a surface atomic structure was successfully fabricated, suggesting the possibility of atomic-scale manipulation of this widely applicable surface of ZnTe. PMID:27877752

Sequential Leaching of Chromium Contaminated Sediments - A Study Characterizing Natural Attenuation

NASA Astrophysics Data System (ADS)

Musa, D.; Ding, M.; Beroff, S.; Rearick, M.; Perkins, G.; WoldeGabriel, G. W.; Ware, D.; Harris, R.; Kluk, E.; Katzman, D.; Reimus, P. W.; Heikoop, J. M.

2015-12-01

Natural attenuation is an important process in slowing down the transport of hexavalent chromium, Cr(VI), an anthropogenic environmental contaminant, either by adsorption of Cr(VI) to sediments, or by reduction to nontoxic trivalent chromium, Cr(III). The capacity and mechanism of attenuation is explored in this sequential leaching study of different particle size fractions of chromium contaminated sediments and similar uncontaminated sediments from the regional aquifer near Los Alamos, New Mexico. Using this leaching protocol each sediment sample is split in two: one half is leached three times using a 0.1 M sodium bicarbonate/carbonate solution, while the second half is leached three times using a 0.01 M nitric acid, followed by two consecutively increasing magnitudes of nitric acid concentrations. Based on the amphoteric nature of chromium, alkaline leaching is used to establish the amount of Cr(VI) sorbed on the sediment, whereas acid leaching is used to establish the amount of Cr(III). The weak acid is predicted to release the attenuated anthropogenic Cr(III), without affecting Cr-bearing minerals. The sequential, stronger, acid is anticipated to leach Cr(III)-incorporated in the minerals. The efficiency and validation of the sequential leaching method is assessed by comparing the leaching behavior of bentonite and biotite samples, with and without loaded Cr(VI). A 97% chromium mass balance of leached Cr(VI)-loaded bentonite and biotite proves the viability of this method for further use on leaching contaminated sediments. By comparing contaminated and uncontaminated sediment leachate results, of chromium and other major and trace elements, the signature of anthropogenic chromium is determined. Further mineralogical characterization of the sediments provides a quantitative measure of the natural attenuation capacity for chromium. Understanding these results is pertinent in delineating the optimal procedure for the remediation of Cr(VI) in the regional aquifer near Los Alamos.

How-To-Do-It: Environmental Pollution Effects Demonstrated by Metal Adsorption in Lichens.

ERIC Educational Resources Information Center

Miller, James E.

1988-01-01

Presents an experiment to demonstrate the degree to which environmental cations are taken up by susceptible lichen organisms in the field. Discusses the preparation of materials, procedures and typical results for this short laboratory exercise. (CW)

40 CFR 86.1111-87 - Test procedures for PCA testing.

Code of Federal Regulations, 2011 CFR

2011-07-01

... in paragraph (a) of § 86.133. (v) The manufacturer may substitute slave tires for the drive wheel... same size as the drive wheel tires. (vi) The cold start exhaust emission test described in § 86.137... well as the likelihood that similar settings will occur on in-use heavy-duty engines or light-duty...

Leisure Time Safety: Fun, Fun, Fun! Proceed with Caution: Consumer Safety in the Home, VI.

ERIC Educational Resources Information Center

Saskatchewan Consumer and Commercial Affairs, Regina.

Exercising caution during recreational activities will ensure that vacations and holidays do not result in tragedy. This booklet outlines some of the activities that require caution. Proper procedures for cycling--including the use of all terrain vehicles (ATVs), roller skating, and skateboarding are illustrated. Swimming can continue to be…

Justice. Law in a Free Society Series. Level VI. Teacher's Guide. Second Edition.

ERIC Educational Resources Information Center

Center for Civic Education, Calabasas, CA.

This teacher's curriculum guide is designed to help high school teachers guide students to develop a better understanding of difficult issues raised by questions of justice. It is hoped that the ideas, observations, questions, and procedures students learn in the curriculum will help them to make informed decisions about how to promote justice and…

34 CFR 682.511 - Procedures for filing a claim.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) The repayment instrument. (iv) A payment history, as described in § 682.414(a)(3)(ii)(I). (v) A collection history, as described in § 682.414(a)(3)(ii)(J). (vi) A copy of the final demand letter if... America of all rights, title, and interest of the lender in the note underlying the claim. (d) Bankruptcy...

34 CFR 682.511 - Procedures for filing a claim.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) The repayment instrument. (iv) A payment history, as described in § 682.414(a)(3)(ii)(I). (v) A collection history, as described in § 682.414(a)(3)(ii)(J). (vi) A copy of the final demand letter if... America of all rights, title, and interest of the lender in the note underlying the claim. (d) Bankruptcy...

34 CFR 682.511 - Procedures for filing a claim.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) The repayment instrument. (iv) A payment history, as described in § 682.414(a)(3)(ii)(I). (v) A collection history, as described in § 682.414(a)(3)(ii)(J). (vi) A copy of the final demand letter if... America of all rights, title, and interest of the lender in the note underlying the claim. (d) Bankruptcy...

Women in Non-Traditional Jobs in the Mid-Willamette Valley Manpower Consortium. A Research Project.

ERIC Educational Resources Information Center

Governor's Commission for Women, Salem, OR.

This study discusses the presence of women in non-traditional positions funded by CETA II and VI and the CETA programs, policies, and procedures offering opportunities for women to enter non-traditional occupations. Information was collected via interviews and questionnaires to determine the status of CETA workers in the Mid-Willamette Valley…

46 CFR 160.176-5 - Approval procedures.

Code of Federal Regulations, 2010 CFR

2010-10-01

... service manual and written guidelines required by §§ 160.176-19(c) and 160.176-19(d) of the part and the user's manual required by § 160.176-21 of this part. (vi) A list of proposed servicing facilities. (4... manufacturer fails to maintain approved servicing facilities that meet § 160.176-19 of this part. (b) Manuals...

Taking Advantage of a Corrosion Problem to Solve a Pollution Problem

ERIC Educational Resources Information Center

Palomar-Ramirez, Carlos F.; Bazan-Martinez, Jose A.; Palomar-Pardave, Manuel E.; Romero-Romo, Mario A.; Ramirez-Silva, Maria Teresa

2011-01-01

Some simple chemistry is used to demonstrate how Fe(II) ions, formed during iron corrosion in acid aqueous solution, can reduce toxic Cr(VI) species, forming soluble Cr(III) and Fe(III) ions. These ions, in turn, can be precipitated by neutralizing the solution. The procedure provides a treatment for industrial wastewaters commonly found in…

War and Peace. Grade Twelve. [Resource Unit VI.] Project Social Studies.

ERIC Educational Resources Information Center

Minnesota Univ., Minneapolis. Project Social Studies Curriculum Center.

This is the sixth of seven resource units for a twelfth grade course on value conflicts and policy decisions. The topic for this unit is war and peace. The objectives are listed as to generalizations, skills, and values. The double-page format related objectives to pertinent content, teaching procedures, and instructional materials. This unit…

38 CFR 18b.74 - Oral argument to the reviewing authority.

Code of Federal Regulations, 2010 CFR

2010-07-01

... argument is to emphasize and clarify the written argument in the briefs. Reading at length from the brief... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Oral argument to the... AFFAIRS (CONTINUED) PRACTICE AND PROCEDURE UNDER TITLE VI OF THE CIVIL RIGHTS ACT OF 1964 AND PART 18 OF...

42 CFR 476.94 - Notice of QIO initial denial determination and changes as a result of a DRG validation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... changes as a result of a DRG validation. 476.94 Section 476.94 Public Health CENTERS FOR MEDICARE... DRG validation. (a) Notice of initial denial determination—(1) Parties to be notified. A QIO must... of identification; (vi) For retrospective review, (excluding DRG validation and post procedure review...

Chromium removal from ground water by Ion exchange resins

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

Skiadas, P.

1994-05-06

The ground water at several monitoring wells at LLNL has been found to exceed the Surface Water Discharge Limits for Cr(VI). Ion exchange resins have been selected for its removal. A research study is underway to determine which commercial resin is preferred for LLNL`s ground water. The choice of an appropriate resin will be based on Cr(VI) exchange capacity, regeneration efficiency, and pH stabilization. A sequestering agent must also be selected to be used for the elimination of scaling at the treatment facilities. The chemistry of ion exchange resins, and instrumentation and procedures are explained and described in the followingmore » paper. Comparison of the different resins tested lead us to the selection of the most effective one to be used in the treatment facilities.« less

Phase transitions of CaCO3 at high P and T determined by in-situ Vibrational Spectroscopy in Diamond-Anvil-Cells

NASA Astrophysics Data System (ADS)

Koch-Müller, Monika; Jahn, Sandro; Birkholz, Natalie; Schade, Ulrich

2014-05-01

Carbonates are the most abundant carbon-bearing minerals on Earth. They can be transported into the upper and lower mantle via subduction processes. Knowledge of the stability of solid carbonates adapting different structures with increasing pressure and temperature is therefore of great importance to understand the structure and dynamics of the Earth. Even for the very simple system CaCO3 the phase relations of at high pressure and temperature are still not fully understood. It has been known for many years that calcite (cc) can adopt different structures with increasing pressure (e.g. Bridgman, 1939: cc-I to III; Tyburczy and Ahrens, 1986: cc-VI). But only recently Merlini et al. (2012) were able to solve the crystal structures of some of these high-pressure polymorphs namely cc-III, cc-IIIb and cc-VI. They report that cc-VI has a higher density then aragonite under the same conditions. To study the stability of the CaCO3-polymorphs, experiments were performed in conventional diamond anvil cells (DAC) at ambient temperatures as a function of pressure up to 30 GPa as well as in internally heated diamond anvil cells (DAC-HT) in the pressure range 9 to 20 GPa and temperatures up to 800 K. As probe for the structural changes we used conventional mid-infrared-, synchrotron far-infrared- and Raman-spectroscopy. Within the cc-III stability field (3 to 15 GPa at room temperature, e.g. Catalli and Williams, 2005) we observed in all types of experiments consistently two different spectral patterns: one at lower P < 5 GPa and another at P > 5 < 15 GPa independent on the starting material and the pressure- and time-path of the experiments. Whether these P-induced structural changes may be linked to the above mentioned different structures of cc-III is not yet clear. Also, in all types of experiments we confirmed the transition of cc-III to cc-VI at about 15 GPa at room temperature. Merlini et al. (2012) speculated that temperature may stabilize the structures of cc-III to lower pressure and surprisingly we found the same for the cc-III to cc-VI transition. The reaction has a negative slope of about -0.007 GPa/K. However, our density-functional theory calculations indicate that cc-VI is still metastable in respect to aragonite at least at zero K. We will prove if temperature and the incorporation of smaller cations than Ca have an influence on the stability relations. References: Bridgman P.W. (1939) Am J Sci, 237, 7 - 18. Catalli K. and Williams Q. (2005) Am Mineral, 90, 1679 - 1682. Merlini M. et al. (2012) EPSL, 333-334, 265 - 271. Tyburczy J. A. and Ahrens T. J. (1986) J Geophysical Research, 91, 4730 - 4744.

Simplified NaCl based (68)Ga concentration and labeling procedure for rapid synthesis of (68)Ga radiopharmaceuticals in high radiochemical purity.

PubMed

Mueller, Dirk; Klette, Ingo; Baum, Richard P; Gottschaldt, M; Schultz, Michael K; Breeman, Wouter A P

2012-08-15

A simple sodium chloride (NaCl) based (68)Ga eluate concentration and labeling method that enables rapid, high-efficiency labeling of DOTA conjugated peptides in high radiochemical purity is described. The method utilizes relatively few reagents and comprises minimal procedural steps. It is particularly well-suited for routine automated synthesis of clinical radiopharmaceuticals. For the (68)Ga generator eluate concentration step, commercially available cation-exchange cartridges and (68)Ga generators were used. The (68)Ga generator eluate was collected by use of a strong cation exchange cartridge. 98% of the total activity of (68)Ga was then eluted from the cation exchange cartridge with 0.5 mL of 5 M NaCl solution containing a small amount of 5.5 M HCl. After buffering with ammonium acetate, the eluate was used directly for radiolabeling of DOTATOC and DOTATATE. The (68)Ga-labeled peptides were obtained in higher radiochemical purity compared to other commonly used procedures, with radiochemical yields greater than 80%. The presence of (68)Ge could not be detected in the final product. The new method obviates the need for organic solvents, which eliminates the required quality control of the final product by gas chromatography, thereby reducing postsynthesis analytical effort significantly. The (68)Ga-labeled products were used directly, with no subsequent purification steps, such as solid-phase extraction. The NaCl method was further evaluated using an automated fluid handling system and it routinely facilitates radiochemical yields in excess of 65% in less than 15 min, with radiochemical purity consistently greater than 99% for the preparation of (68)Ga-DOTATOC.

Syntheses, Crystal Structures, and Properties of New Layered Tungsten(VI)-Containing Materials Based on the Hexagonal-WO 3 Structure: M2(WO 3) 3SeO 3 ( M = NH 4, Rb, Cs)

NASA Astrophysics Data System (ADS)

Harrison, William T. A.; Dussack, Laurie L.; Vogt, Thomas; Jacobson, Allan J.

1995-11-01

The hydrothermal syntheses and crystal structures of (NH4)2(WO3)3SeO3 and Cs2(WO3)3SeO3, two new noncentrosymmetric, layered tungsten(VI)-containing phases are reported. Infrared, Raman, and thermogravimetric data are also presented. (NH4)2(WO3)3SeO3 and Cs2(WO3)3SeO3 are isostructural phases built up from hexagonal-tungsten-oxide-like, anionic layers of vertex-sharing WO6 octahedra, capped on one side by Se atoms (as selenite groups). Interlayer NH+4 or Cs+ cations provide charge balance. The full H-bonding scheme in (NH4)2(WO3)3SeO3 has been elucidated from Rietveld refinement against neutron powder diffraction data. The WO6 octahedra display a 3 short + 3 long W-O bond-distance distribution within the WO6 unit in both these phases. (NH4)2(WO3)3SeO3 and Cs2(WO3)3SeO3 are isostructural with their molybdenum(VI)-containing analogues (NH4)2(MoO3)3SeO3 and Cs2 (MoO3)3SeO3. Crystal data: (NH4)2(WO3)3SeO3, Mr = 858.58, hexagonal, space group P63 (No. 173), a = 7.2291(2) Å, c = 12.1486(3) Å, V = 549.82(3) Å3, Z = 2, Rp = 1.81%, and Rwp = 2.29% (2938 neutron powder data). Cs2(WO3)3SeO3, Mr = 1088.31, hexagonal, space group P63 (no. 173), a = 7.2615(2) Å, c = 12.5426(3) Å, V = 572.75(3) Å3, Z = 2, Rp = 4.84%, and Rwp = 5.98% (2588 neutron powder data).

Setting of commercial glass ionomer cement Fuji IX by (27)Al and (19)F MAS-NMR.

PubMed

Munhoz, Tais; Karpukhina, Natalia; Hill, Robert G; Law, Robert V; De Almeida, L H

2010-04-01

To investigate the long term setting reaction in the glass ionomer restorative, Fuji IX, by monitoring the structural evolution of aluminium and fluorine species using (27)Al and (19)F MAS-NMR spectroscopy. Fuji IX cements aged from 5min up to 3 months were prepared according to the manufacturer instructions from the commercial material. The (27)Al and (19)F MAS-NMR studies were carried out on powders made after terminating the setting reaction. (27)Al MAS-NMR results show conversion of aluminium from the glass phase, where it has coordination number four, Al(IV), into the cement matrix where it has a coordination number of six, Al(VI). At least two different Al(VI) species were detected at short ageing time cements. Assignment of these species is discussed and compared with the data from other sources. The possibility for a condensed aluminium species [Al(13)(OH)(24)(H(2)O)(12)](7+) to form is considered. The ratio of aluminium in the cement, Al(VI), to the remaining unreacted in glass has been evaluated by deconvolution of the spectra. Various theoretical ratios of aluminium species in the cement matrix to the unreacted ones remaining in glass have been estimated. The (19)F MAS-NMR spectra are identical for the glass and cements at the early times and contain a dominant signal assigned to Al-F-Sr(n). The data confirms that the conversion of aluminium is a diffusion-controlled process at early stage less than 1h and it is largely complete between 1 and 6h. The comparison with the experimental data shows that the majority of aluminium cations do not form tricarboxylates but are coordinated with one or two carboxylic groups and other ligands. Insufficient amount of water and excess of glass in this cement formulation affect glass degradation mechanism. Crown Copyright 2009. Published by Elsevier Ltd. All rights reserved.

40 CFR 63.7142 - What are the requirements for claiming area source status?

Code of Federal Regulations, 2013 CFR

2013-07-01

... test must be repeated. (v) The post-test analyte spike procedure of section 11.2.7 of ASTM Method D6735... (3) ASTM Method D6735-01, Standard Test Method for Measurement of Gaseous Chlorides and Fluorides...)(3)(i) through (vi) of this section are followed. (i) A test must include three or more runs in which...

40 CFR 63.7142 - What are the requirements for claiming area source status?

Code of Federal Regulations, 2011 CFR

2011-07-01

... test must be repeated. (v) The post-test analyte spike procedure of section 11.2.7 of ASTM Method D6735... (3) ASTM Method D6735-01, Standard Test Method for Measurement of Gaseous Chlorides and Fluorides...)(3)(i) through (vi) of this section are followed. (i) A test must include three or more runs in which...

40 CFR 63.7142 - What are the requirements for claiming area source status?

Code of Federal Regulations, 2012 CFR

2012-07-01

... test must be repeated. (v) The post-test analyte spike procedure of section 11.2.7 of ASTM Method D6735... (3) ASTM Method D6735-01, Standard Test Method for Measurement of Gaseous Chlorides and Fluorides...)(3)(i) through (vi) of this section are followed. (i) A test must include three or more runs in which...

40 CFR 63.7142 - What are the requirements for claiming area source status?

Code of Federal Regulations, 2010 CFR

2010-07-01

... test must be repeated. (v) The post-test analyte spike procedure of section 11.2.7 of ASTM Method D6735... (3) ASTM Method D6735-01, Standard Test Method for Measurement of Gaseous Chlorides and Fluorides...)(3)(i) through (vi) of this section are followed. (i) A test must include three or more runs in which...

40 CFR 63.7142 - What are the requirements for claiming area source status?

Code of Federal Regulations, 2014 CFR

2014-07-01

... test must be repeated. (v) The post-test analyte spike procedure of section 11.2.7 of ASTM Method D6735... (3) ASTM Method D6735-01, Standard Test Method for Measurement of Gaseous Chlorides and Fluorides...)(3)(i) through (vi) of this section are followed. (i) A test must include three or more runs in which...

42 CFR 51d.8 - Which other HHS regulations apply to these awards?

Code of Federal Regulations, 2011 CFR

2011-10-01

... title VI of the Civil Rights Act of 1964 45 CFR part 81—Practice and procedure for hearings under part... 42 Public Health 1 2011-10-01 2011-10-01 false Which other HHS regulations apply to these awards? 51d.8 Section 51d.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

42 CFR 51d.8 - Which other HHS regulations apply to these awards?

Code of Federal Regulations, 2010 CFR

2010-10-01

... title VI of the Civil Rights Act of 1964 45 CFR part 81—Practice and procedure for hearings under part... 42 Public Health 1 2010-10-01 2010-10-01 false Which other HHS regulations apply to these awards? 51d.8 Section 51d.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

42 CFR 51b.105 - Which other HHS regulations apply to these grants?

Code of Federal Regulations, 2013 CFR

2013-10-01

... effectuation of title VI of the Civil Rights Act of 1964 45 CFR part 81—Practice and procedure for hearings... 42 Public Health 1 2013-10-01 2013-10-01 false Which other HHS regulations apply to these grants? 51b.105 Section 51b.105 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

42 CFR 51b.105 - Which other HHS regulations apply to these grants?

Code of Federal Regulations, 2012 CFR

2012-10-01

... effectuation of title VI of the Civil Rights Act of 1964 45 CFR part 81—Practice and procedure for hearings... 42 Public Health 1 2012-10-01 2012-10-01 false Which other HHS regulations apply to these grants? 51b.105 Section 51b.105 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

42 CFR 51b.105 - Which other HHS regulations apply to these grants?

Code of Federal Regulations, 2011 CFR

2011-10-01

... effectuation of title VI of the Civil Rights Act of 1964 45 CFR part 81—Practice and procedure for hearings... 42 Public Health 1 2011-10-01 2011-10-01 false Which other HHS regulations apply to these grants? 51b.105 Section 51b.105 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

42 CFR 51b.105 - Which other HHS regulations apply to these grants?

Code of Federal Regulations, 2014 CFR

2014-10-01

... effectuation of title VI of the Civil Rights Act of 1964 45 CFR part 81—Practice and procedure for hearings... 42 Public Health 1 2014-10-01 2014-10-01 false Which other HHS regulations apply to these grants? 51b.105 Section 51b.105 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

42 CFR 51b.105 - Which other HHS regulations apply to these grants?

Code of Federal Regulations, 2010 CFR

2010-10-01

... effectuation of title VI of the Civil Rights Act of 1964 45 CFR part 81—Practice and procedure for hearings... 42 Public Health 1 2010-10-01 2010-10-01 false Which other HHS regulations apply to these grants? 51b.105 Section 51b.105 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

49 CFR 26.53 - What are the good faith efforts procedures recipients follow in situations where there are...

Code of Federal Regulations, 2011 CFR

2011-10-01

... TRANSPORTATION FINANCIAL ASSISTANCE PROGRAMS Goals, Good Faith Efforts, and Counting § 26.53 What are the good...: (i) The names and addresses of DBE firms that will participate in the contract; (ii) A description of... in the contract as provided in the prime contractor's commitment; and (vi) If the contract goal is...

40 CFR 142.16 - Special primacy requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... enforceable requirements and procedures when the State adds to or changes the requirements under: (i) Table 1... distribution system that is out of compliance; (iii) Table 1 of 40 CFR 141.202(a) (Items (5), (6), and (9))—To... require a different form and manner of delivery for Tier 1, 2 and 3 public notices. (vi) Table 1 to 40 CFR...

Separation of Pb, Bi and Po by cation exchange resin

DOE PAGES

Kmak, Kelly N.; Despotopulos, John D.; Shaughnessy, Dawn A.

2017-09-27

In this paper, a separation of 209Po, 207Bi and 212Pb using AG 50Wx8 and AG MP 50 cation exchange resins in an HCl medium was developed. A procedure in which Po(IV) elutes first in 0.2 M HCl, followed by Bi(III) in 0.4 M HCl and finally Pb(II) in 2 M HCl was established. The separation using AG 50Wx8 provides a much better elution profile than that of AG MP 50 with no overlap between the elution bands. Finally, this separation has the potential to be used as an isotope generator for producing 210Po from 210Pb.

Simple method for determination of selenium in biological materials by flameless atomic-absorption spectrometry using a carbon-tube atomizer.

PubMed

Ishizaki, M

1978-03-01

A method for determination of selenium in biological materials by flameless atomic-absorption spectrometry using a carbon-tube atomizer is described. The sample is burned by an oxygen-flask combustion procedure, the resulting solution is treated with a cation-exchange resin to eliminate interfering cations, the selenium is extracted with dithizone in carbon tetrachloride and the resulting selenium dithizonate is combined with nickel nitrate in the carbon tube to enhance the sensitivity for selenium and avoid volatilization losses. The method measures selenium concentrations as low as 0.01 mug/g with a relative standard deviation of 8%.

Method for loading lipsomes with ionizable phosphorylated hydrophobic compounds, pharmaceutical preparations and a method for administering the preparations

DOEpatents

Mehlhorn, Rolf Joachim

1998-10-27

A method of entrapping ionizable compounds, preferably phosphorylated hydrophobic compounds, into liposomes having transmembrane gradients is disclosed. The procedures involve forming liposomes in an acidic medium or a basic medium, adding to the acidic medium a cationic compound or to the basic medium an anionic compound and then adding a base to the cationic-containing medium or an acid to the anionic-containing medium, thereby inducing the ionizable compound into the liposomes' internal aqueous phase. The compound-entrapped liposomes prepared in accordance with the disclosed methods may be used as pharmaceutical preparations. Methods of administering such pharmaceutical preparations are also disclosed.

The chemistry of cationic polyphosphorus cages – syntheses, structure and reactivity

PubMed Central

Holthausen, Michael H.

2014-01-01

The aim of this review is to provide a comprehensive view of the chemistry of cationic polyphosphorus cages. The synthetic protocols established for their preparation, which are all based on the functionalization of P4, and their intriguing follow-up chemistry are highlighted. In addition, this review intends to foster the interest of the inorganic, organic, catalytic and material oriented chemical communities in the versatile field of polyphosphorus cage compounds. In the long term, this is envisioned to contribute to the development of new synthetic procedures for the functionalization of P4 and its transformation into (organo-)phosphorus compounds and materials of added value. PMID:24740160

Changes in fluorescent emission of cationic fluorophores in the presence of n-alkanes and alcohols in different polarity solvents

NASA Astrophysics Data System (ADS)

Delgado-Camón, Arantzazu; Garriga, Rosa; Mateos, Elena; Cebolla, Vicente L.; Galbán, Javier; Membrado, Luis; Marcos, Susana de; Gálvez, Eva M.

2011-01-01

Berberine and coralyne experience either fluorescence enhancement or quenching when long hydrocarbon chain compounds (e.g., n-alkanes or alcohols) are added to their solutions, depending on solvent polarity. In polar solvents, as methanol or acetonitrile, the added compounds provide an apolar microenvironment that hinders alternative relaxation mechanisms, favouring fluorescence emission. However, alkane additions produce quenching in dichloromethane, which has been explained taking into account ion pairing between cationic fluorophore and counterion. The strong quenching measured after alcohol additions in dichloromethane suggests reversed micelle formation. Procedures and results described here may find practical applications in the development of analytical methods.

A solid phase extraction-ion chromatography with conductivity detection procedure for determining cationic surfactants in surface water samples.

PubMed

Olkowska, Ewa; Polkowska, Żaneta; Namieśnik, Jacek

2013-11-15

A new analytical procedure for the simultaneous determination of individual cationic surfactants (alkyl benzyl dimethyl ammonium chlorides) in surface water samples has been developed. We describe this methodology for the first time: it involves the application of solid phase extraction (SPE-for sample preparation) coupled with ion chromatography-conductivity detection (IC-CD-for the final determination). Mean recoveries of analytes between 79% and 93%, and overall method quantification limits in the range from 0.0018 to 0.038 μg/mL for surface water and CRM samples were achieved. The methodology was applied to the determination of individual alkyl benzyl quaternary ammonium compounds in environmental samples (reservoir water) and enables their presence in such types of waters to be confirmed. In addition, it is a simpler, less time-consuming, labour-intensive, avoiding use of toxic chloroform and significantly less expensive methodology than previously described approaches (liquid-liquid extraction coupled with liquid chromatography-mass spectrometry). Copyright © 2013 Elsevier B.V. All rights reserved.