Enhanced Cr(VI) reduction and As(III) oxidation in ice phase: Important role of dissolved organic matter from biochar

Energy Technology Data Exchange (ETDEWEB)

Dong, Xiaoling [Department of Soil and Water Science, University of Florida, Gainesville, FL 32611 (United States); Ma, Lena Q., E-mail: lqma@ufl.edu [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210046 (China); Department of Soil and Water Science, University of Florida, Gainesville, FL 32611 (United States); Gress, Julia; Harris, Willie [Department of Soil and Water Science, University of Florida, Gainesville, FL 32611 (United States); Li, Yuncong [Soil and Water Science Department, Tropical Research and Education Center, University of Florida, Homestead, FL 33031-3314 (United States)

2014-02-01

Graphical abstract: - Highlights: • Biochar-derived dissolved organic matter (DOM) effectively reduced Cr(VI) and oxidized As(III). • Cr(VI) and As(III) could serve as a redox couple. • Cr(VI) and As(III) redox conversion was more effective in the ice phase than aqueous phase. • FTIR and ESR showed that biochar DOM served as both electron donor and acceptor. - Abstract: This study evaluated the impact of DOM from two biochars (sugar beet tailing and Brazilian pepper) on Cr(VI) reduction and As(III) oxidation in both ice and aqueous phases with a soil DOM as control. Increasing DOM concentration from 3 to 300 mg C L{sup −1} enhanced Cr(VI) reduction from 20% to 100% and As(III) oxidation from 6.2% to 25%; however, Cr(VI) reduction decreased from 80–86% to negligible while As(III) oxidation increased from negligible to 18–19% with increasing pH from 2 to 10. Electron spin resonance study suggested semiquinone radicals in DOM were involved in As(III) oxidation while Fourier transform infrared analysis suggested that carboxylic groups in DOM participated in both Cr(VI) reduction and As(III) oxidation. During Cr(VI) reduction, part of DOM (∼10%) was oxidized to CO{sub 2}. The enhanced conversion of Cr(VI) and As(III) in the ice phase was due to the freeze concentration effect with elevated concentrations of electron donors and electron acceptors in the grain boundary. Though DOM enhanced both Cr(VI) reduction and As(III)oxidation, Cr(VI) reduction coupled with As(III) oxidation occurred in absence of DOM. The role of DOM, Cr(VI) and/or As(III) in Cr and As transformation may provide new insights into their speciation and toxicity in cold regions.

Altered corneal stromal matrix organization is associated with mucopolysaccharidosis I, III and VI.

Science.gov (United States)

Alroy, J; Haskins, M; Birk, D E

1999-05-01

The presence of cloudy corneas is a prominent feature of mucopolysaccharidosis (MPS) types I and VI, but not MPS IIIA or IIIB. The cause of corneal cloudiness in MPS I and VI is speculative. Transparency of the cornea is dependent on the uniform diameter and the regular spacing and arrangement of the collagen fibrils within the stroma. Alterations in the spacing of collagen fibrils in a variety of conditions including corneal edema, scars, and macular corneal dystrophy is clinically manifested as corneal opacity. The purpose of this study was to compare the structural organization of the stromal extracellular matrix of normal corneas with that of MPS corneas. The size and arrangement of collagen fibrils in cloudy corneas from patients with MPS I were examined. The alterations observed were an increased mean fibril diameter with a broader distribution in the MPS corneas. The MPS I corneas also had altered fibril spacing and more irregular packing compared with normal control corneas. The clear corneas of patients with MPS IIIA and IIIB also showed increases in mean fibril diameter and fibril spacing. However, there was less variation indicating more regularity than seen in MPS I. In addition, corneas from cat models of certain MPS were compared to the human corneas. Cats with MPS I and VI, as well as normal control cats, were examined. Structural alterations comparable to those seen in human MPS corneas were seen in MPS I and VI cats relative to normal clear corneas. The findings suggest that cloudy corneas in MPS I and VI are in part a consequence of structural alterations in the corneal stroma, including abnormal spacing, size, and arrangement of collagen fibrils. Copyright 1999 Academic Press.

II-I2-IV-VI4 (II = Sr,Ba; I = Cu,Ag; IV = Ge,Sn; VI = S,Se): Earth-Abundant Chalcogenides for Thin Film Photovoltaics

Science.gov (United States)

Zhu, Tong; Huhn, William P.; Shin, Donghyeop; Mitzi, David B.; Blum, Volker; Saparov, Bayrammurad

Chalcogenides such as CdTe, CIGSSe, and CZTSSe are successful for thin film photovoltaics (PV) but contain elements that are rare, toxic, or prone to the formation of detrimental antisite disorder. Recently, the BaCu2SnS4-xSex system has been shown to offer a prospective path to circumvent these problems. While early prototypes show efficiencies of a few percent, many avenues remain to optimize the materials, including the underlying chemical composition. In this work, we explore 16 compounds II-I2-IV-VI4 to help identify new candidate materials for PV, with predictions based on both known experimental and computationally derived structures that belong to five different space groups. We employ hybrid density functional theory (HSE06) to explore the band gap tunability by substituting different elements, and other characteristics such as the effective mass and the absorption coefficient. Compounds containing Cu (rather than Ag) are found to have direct or nearly direct band gaps. Depending on the compound, replacing S with Se leads to a decrease of the predicted band gaps by 0.2-0.8 eV and to somewhat decreasing hole effective masses.

Kinetics of Cr(III) and Cr(VI) removal from water by two floating macrophytes.

Science.gov (United States)

Maine, M A; Hadad, H R; Sánchez, G; Caffaratti, S; Pedro, M C

2016-01-01

The aim of this work was to compare Cr(III) and Cr(VI) removal kinetics from water by Pistia stratiotes and Salvinia herzogii. The accumulation in plant tissues and the effects of both Cr forms on plant growth were also evaluated. Plants were exposed to 2 and 6 mg L(-1) of Cr(III) or Cr(VI) during 30 days. At the end of the experiment, Cr(VI) removal percentages were significantly lower than those obtained for Cr(III) for both macrophytes. Cr(III) removal kinetics involved a fast and a slow component. The fast component was primarily responsible for Cr(III) removal while Cr(VI) removal kinetics involved only a slow process. Cr accumulated principally in the roots. In the Cr(VI) treatments a higher translocation from roots to aerial parts than in Cr(III) treatments was observed. Both macrophytes demonstrated a high ability to remove Cr(III) but not Cr(VI). Cr(III) inhibited the growth at the highest studied concentration of both macrophytes while Cr(VI) caused senescence. These results have important implications in the use of constructed wetlands for secondary industrial wastewater treatment. Common primary treatments of effluents containing Cr(VI) consists in its reduction to Cr(III). Cr(III) concentrations in these effluents are normally below the highest studied concentrations in this work.

Lateral feedback from monophasic horizontal cells to cones in carp retina. I. Experiments

NARCIS (Netherlands)

Kamermans, M.; van Dijk, B. W.; Spekreijse, H.; Zweypfenning, R. C.

1989-01-01

The spatial and color coding of the monophasic horizontal cells were studied in light- and dark-adapted retinae. Slit displacement experiments revealed differences in integration area for the different cone inputs of the monophasic horizontal cells. The integration area measured with a 670-nm

General synthesis of (salen)ruthenium(III) complexes via N...N coupling of (salen)ruthenium(VI) nitrides.

Science.gov (United States)

Man, Wai-Lun; Kwong, Hoi-Ki; Lam, William W Y; Xiang, Jing; Wong, Tsz-Wing; Lam, Wing-Hong; Wong, Wing-Tak; Peng, Shie-Ming; Lau, Tai-Chu

2008-07-07

Reaction of [Ru (VI)(N)(L (1))(MeOH)] (+) (L (1) = N, N'-bis(salicylidene)- o-cyclohexylenediamine dianion) with excess pyridine in CH 3CN produces [Ru (III)(L (1))(py) 2] (+) and N 2. The proposed mechanism involves initial equilibrium formation of [Ru (VI)(N)(L (1))(py)] (+), which undergoes rapid N...N coupling to produce [(py)(L (1))Ru (III) N N-Ru (III)(L (1))(py)] (2+); this is followed by pyridine substituion to give the final product. This ligand-induced N...N coupling of Ru (VI)N is utilized in the preparation of a series of new ruthenium(III) salen complexes, [Ru (III)(L)(X) 2] (+/-) (L = salen ligand; X = H 2O, 1-MeIm, py, Me 2SO, PhNH 2, ( t )BuNH 2, Cl (-) or CN (-)). The structures of [Ru (III)(L (1))(NH 2Ph) 2](PF 6) ( 6), K[Ru (III)(L (1))(CN) 2] ( 9), [Ru (III)(L (2))(NCCH 3) 2][Au (I)(CN) 2] ( 11) (L (2) = N, N'-bis(salicylidene)- o-phenylenediamine dianion) and [N ( n )Bu 4][Ru (III)(L (3))Cl 2] ( 12) (L (3) = N, N'-bis(salicylidene)ethylenediamine dianion) have been determined by X-ray crystallography.

Perovskites Ba/sub 2/Bsub(1/2)sup(I)Bsub(1/2)sup(III)Usup(VI)O/sub 6/

Energy Technology Data Exchange (ETDEWEB)

Roller, H; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

1978-11-01

Compounds of type Ba/sub 2/Lisub(1/2)Bsub(1/2)sup(III)Usup(VI)O/sub 6/ and Ba/sub 2/Nasub(1/2)Bsub(1/2)sup(III)Usup(VI)O/sub 6/ are formed with Bsup(III) = La, Nd, Sm, Gd, Y, In as red to reddish brown perovskites. They are for Bsup(III) = La, Nd and Sm polymorphic. With Bsup(III) = La both HT-forms crystallize cubic. In the Li series the HT-modifications with Bsup(III) = Nd, Sm are monoclinic (a < c/..sqrt..2 < b) and in the Na series rhombic (c/..sqrt..2 < a < b); the corresponding Gd, Y, and In compounds have the same structure. The transformation HT ..-->.. TT is reversible. The TT modifications crystallize monoclinic (a < b < c/..sqrt..2). Unlike the HT forms an increase of c and a decrease of a and b is observed, the cell volumina rested nearly unchanged. The origin for the transformation are order disorder phenomena.

Kinetics and Products of Chromium(VI) Reduction by Iron(II/III)-Bearing Clay Minerals.

Science.gov (United States)

Joe-Wong, Claresta; Brown, Gordon E; Maher, Kate

2017-09-05

Hexavalent chromium is a water-soluble pollutant, the mobility of which can be controlled by reduction of Cr(VI) to less soluble, environmentally benign Cr(III). Iron(II/III)-bearing clay minerals are widespread potential reductants of Cr(VI), but the kinetics and pathways of Cr(VI) reduction by such clay minerals are poorly understood. We reacted aqueous Cr(VI) with two abiotically reduced clay minerals: an Fe-poor montmorillonite and an Fe-rich nontronite. The effects of ionic strength, pH, total Fe content, and the fraction of reduced structural Fe(II) [Fe(II)/Fe(total)] were examined. The last variable had the largest effect on Cr(VI) reduction kinetics: for both clay minerals, the rate constant of Cr(VI) reduction varies by more than 3 orders of magnitude with Fe(II)/Fe(total) and is described by a linear free energy relationship. Under all conditions examined, Cr and Fe K-edge X-ray absorption near-edge structure spectra show that the main Cr-bearing product is a Cr(III)-hydroxide and that Fe remains in the clay structure after reacting with Cr(VI). This study helps to quantify our understanding of the kinetics of Cr(VI) reduction by Fe(II/III)-bearing clay minerals and may improve predictions of Cr(VI) behavior in subsurface environments.

Methylbutylmalonamide as an extractant for U(VI), Pu(IV), and Am(III)

International Nuclear Information System (INIS)

Nair, G.M.; Prabhu, D.R.; Mahajan, G.R.

1994-01-01

The unsymmetrical diamide methylbutylmalonamide has been synthesized and used in the extraction of U(VI), Pu(IV), and Am(III) in benzene medium. The distribution ratio for three cations was found to increase with increasing aqueous nitric acid concentration. U(VI) and Pu(IV) were found to be extracted as disolvates while Am(III) as a trisolvate. The thermodynamic parameters determined by the temperature variation method showed the extraction reactions to be mainly enthalphy-controlled. Am(III) was found to be back-extracted with dilute nitric acid, while Pu(IV) by dilute nitric acid - hydrofluoric acid mixture and U(VI) by dilute sodium carbonate solution. (author) 6 refs.; 3 figs.; 2 tabs

Single-particle spectroscopy of I-III-VI semiconductor nanocrystals: spectral diffusion and suppression of blinking by two-color excitation.

Science.gov (United States)

Sharma, Dharmendar Kumar; Hirata, Shuzo; Bujak, Lukasz; Biju, Vasudevanpillai; Kameyama, Tatsuya; Kishi, Marino; Torimoto, Tsukasa; Vacha, Martin

2016-07-14

Ternary I-III-VI semiconductor nanocrystals have been explored as non-toxic alternatives to II-VI semiconductors for optoelectronic and sensing applications, but large photoluminescence spectral width and moderate brightness restrict their practical use. Here, using single-particle photoluminescence spectroscopy on nanocrystals of (AgIn)xZn2(1-x)S2 we show that the photoluminescence band is inhomogeneously broadened and that size distribution is the dominant factor in the broadening. The residual homogeneous linewidth of individual nanocrystals reaches up to 75% of the ensemble spectral width. Single nanocrystals undergo spectral diffusion which also contributes to the inhomogeneous band. Excitation with two lasers with energies above and below the bandgap reveals coexistence of two emitting donor states within one particle. Spectral diffusion in such particles is due to temporal activation and deactivation of one such state. Filling of a trap state with a lower-energy laser enables optical modulation of photoluminescence intermittency (blinking) and leads to an almost two-fold increase in brightness.

Energy Transfer between U(VI) and Eu(III) Ions Adsorbed on a Silica Surface

Energy Technology Data Exchange (ETDEWEB)

Park, K. K.; Cha, W.; Cho, H. R.; Im, H. J.; Jung, E. C.; Song, K. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2011-05-15

Understanding of chemical behavior of actinide in a groundwater flow is important for assessing the possibility of their migration with water flows in a radioactive waste disposal site. Uranium is ubiquitous in the environment and a major actinide in a nuclear fuel cycle. Americium and curium having isotopes of long half life are minor actinides in a spent fuel. If a minor actinide coexists with uranium in a groundwater flow, some interactions between them could be expected such as minor actinide adsorption onto uranium precipitates and competition with each other for an adsorption to a mineral surface site. Eu(III) ion is frequently used as a chemical analogue of Am(III) and Cm(III) ions in a migration chemistry. The luminescent spectra of U(VI) and Eu(III) ions show a dependency on the coordination symmetry around them, and the changes in intensity or bandwidth of spectra can yield valuable information on their local environment. The luminescent lifetime also strongly depends on the coordination environment, and its measurement is valuable in probe studies on micro-heterogeneous systems. The excited U(VI) ion can be quenched through Stern.Volmer process, hydrolysis of excited species, exciplex formation, electron transfer or energy transfer. In case of U(VI)-Eu(III) system, the interaction between two ions can be studied by measuring the effect of Eu(III) ion on the quenching of U(VI) ion luminescence. There are only a few investigations on the interaction between an excited U(VI) ion and a lanthanide(III) ion. In perchlorate solution, the energy transfer to Eu(III) ion occurred only in solutions of pH>3.87. In this study, the quenching of U(VI) luminescence by Eu(III) on a silica surface was measured. The results will be discussed on the basis of a chemical interaction between them

Multicolor (UV-IR) Photodetectors Based on Lattice-Matched 6.1 A II/VI and III/V Semiconductors

Science.gov (United States)

2015-08-27

copyright information. 13. SUPPLEMENTARY NOTES. Enter information not included elsewhere such as: prepared in cooperation with; translation of; report...II-VI heterojunctions such as multi-color photodetectors and solar cells [2]. Mixing lattice-matched II-VI and III-V semiconductors could be an...at 77 K, further silicon oxide surface passivation can be done to suppress the surface leakage [10] in the future work. Figure 10 The dark I-V

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

International Nuclear Information System (INIS)

Music, S.

1985-01-01

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

Species dependent radiotracer study of Cr(VI) and Cr(III) using an aqueous biphasic system

Energy Technology Data Exchange (ETDEWEB)

Roy, K.; Lahiri, S. [Chemical Sciences Div., Saha Inst. of Nuclear Physics, Kolkata (India)

2008-07-01

The speciation study of Cr(III) and Cr(VI) was carried out using a polyethylene glycol (PEG) based aqueous biphasic extraction system (ABS). Neutron activated Cr(III) and Cr(VI) salts were assayed in a HPGe detector before and after employing aqueous biphasic extraction. Different salts of various salting out abilities were taken as the salt rich phase. The best condition for extraction of Cr(VI) and the maximum differential attitude of ABS to Cr(VI) and Cr(III) was observed when 2 M Na{sub 2}SO{sub 4} and PEG 4000 (50% w/w) solutions were used. Cr(III) can also be extracted by the PEG with prior complexation with diphenylthiocarbazone (dithizone). The chromium dithizonate complex is quantitatively extracted by the PEG rich phase. (orig.)

Correlation between bulk- and surface chemistry of Cr-tanned leather and the release of Cr(III) and Cr(VI)

Energy Technology Data Exchange (ETDEWEB)

Hedberg, Yolanda S., E-mail: yolanda@kth.se [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, SE-10044 Stockholm (Sweden); Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-17177 Stockholm (Sweden); Lidén, Carola, E-mail: carola.liden@ki.se [Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-17177 Stockholm (Sweden); Odnevall Wallinder, Inger, E-mail: ingero@kth.se [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science, SE-10044 Stockholm (Sweden)

2014-09-15

Graphical abstract: - Highlights: • Released reducing/complexing leather-specific species can reduce released Cr(VI). • No co-released species enable the formation of Cr(VI) in solution. • The major Cr species released from leather in phosphate buffer was Cr(III) (>82%). • No Cr(VI) was released into artificial sweat. - Abstract: About 1–3% of the adult general population in Europe is allergic to chromium (Cr). The assessment of the potential release of Cr(III) and Cr(VI) from leather is hence important from a human health and environmental risk perspective. The Cr(VI) content in leather was recently restricted in the European Union. The aim of this study was to assess possible correlations between the bulk and surface chemistry of leather, released Cr(III) and Cr(VI), and capacities of co-released leather specific species to reduce and complex released Cr. Four differently tanned leathers were characterized by scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and the diphenylcarbazide colorimetric method. Their characteristics were compared with results on Cr(III) and Cr(VI) release into artificial sweat (ASW, pH < 6.5) and phosphate buffer (PB, pH 7.5–8.0), measured by means of spectrophotometry and atomic absorption spectroscopy. Co-released leather-specific species were shown to reduce Cr(VI), both in ASW and in PB. Their reduction capacities correlated with findings of the surface content of Cr and of released Cr. Leather samples without this capacity, and with less aromatic surface groups visible by ATR-FTIR, revealed Cr(VI) both at the surface and in solution (PB)

Expression of adenylyl cyclase types III and VI in human hyperfunctioning thyroid nodules.

Science.gov (United States)

Celano, M; Arturi, F; Presta, I; Bruno, R; Scarpelli, D; Calvagno, M G; Cristofaro, C; Bulotta, S; Giannasio, P; Sacco, R; Filetti, S; Russo, D

2003-05-30

Hyperfunctioning thyroid nodules are characterized by the presence of spontaneous somatic mutations responsible for constitutive activation of the cAMP pathway. However, alterations affecting other elements of the cAMP signaling system may counteract the effects of the mutations. In this study, the expression of the adenylyl cyclase (AC) types III and VI was investigated by Western blot in 18 hyperfunctioning thyroid nodules; in 12 samples, we also assessed the presence of TSH receptor (TSHR) or gsp mutations and levels of AC VI and III mRNA. We found that the expression of nodular AC VI (but not AC III) was significantly lower (85.1% of normal, P=0.014) than the expression of both adenylyl cycles types of perinodular tissue from the same patients. Slightly, but not significant differences were detected in nodules with or without mutations and AC protein levels generally showed correlation with the levels of the transcripts detected by RT-PCR. In addition, AC III and AC VI expression levels within a given nodule were characterized by a significant positive correlation. These findings indicate that a diminished expression of AC type VI may be part of the mechanisms occurring in the hyperfunctioning nodules, independently of the presence of TSHR or gsp mutations, which influence the resulting phenotype.

On halide derivatives of rare-earth metal(III) oxidomolybdates(VI) and -tungstates(VI)

International Nuclear Information System (INIS)

Schleid, Thomas; Hartenbach, Ingo

2016-01-01

Halide derivatives of rare-earth metal(III) oxidomolybdates(VI) have been investigated comprehensively over the last decade comprising the halogens fluorine, chlorine, and bromine. Iodide-containing compounds are so far unknown. The simple composition REXMoO 4 (RE=rare-earth element, X=halogen) is realized for X=F almost throughout the complete lanthanide series as well as for yttrium. While ytterbium and lutetium do not form any fluoride derivative, for lanthanum, only a fluoride-deprived compound with the formula La 3 FMo 4 O 16 is realized. Moreover, molybdenum-rich compounds with the formula REXMo 2 O 7 are also known for yttrium and the smaller lanthanoids. For X=Cl the composition REClMoO 4 is known for yttrium and the whole lanthanide series, although, four different structure types were identified. Almost the same holds for X=Br, however, only two different structure types are realized in this class of compounds. In the case of halide derivatives of rare-earth metal(III) oxidotungstates(VI) the composition REXWO 4 is found for chlorides and bromides only, so far. Due to the similar size of Mo 6+ and W 6+ cations, the structures found for the tungstates are basically the same as for the molybdates. With the larger lanthanides, the representatives for both chloride and bromide derivates exhibit similar structural motifs as seen in the molybdates, however, the crystal structure cannot be determined reliably. In case of the smaller lanthanoids, the chloride derivatives are isostructural with the respective molybdates, although the existence ranges differ slightly. The same is true for rare-earth metal(III) bromide oxidotungstates(VI).

Impact of Fe(III) as an effective electron-shuttle mediator for enhanced Cr(VI) reduction in microbial fuel cells: Reduction of diffusional resistances and cathode overpotentials

Energy Technology Data Exchange (ETDEWEB)

Wang, Qiang [Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Huang, Liping, E-mail: lipinghuang@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Pan, Yuzhen [College of Chemistry, Dalian University of Technology, Dalian 116024 (China); Quan, Xie [Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Li Puma, Gianluca, E-mail: g.lipuma@lboro.ac.uk [Environmental Nanocatalysis & Photoreaction Engineering, Department of Chemical Engineering, Loughborough University, Loughborough LE11 3TU (United Kingdom)

2017-01-05

Highlights: • Fe(III) shuttles electrons for enhanced reduction of Cr(VI) in MFCs. • The coulombic efficiency increases by 1.6 fold in the presence of Fe(III). • The reduction of Cr(VI) occurs via an indirect Fe(III) mediation mechanism. • Fe(III) decreases the diffusional resistances and the cathode overpotentials. - Abstract: The role of Fe(III) was investigated as an electron-shuttle mediator to enhance the reduction rate of the toxic heavy metal hexavalent chromium (Cr(VI)) in wastewaters, using microbial fuel cells (MFCs). The direct reduction of chromate (CrO{sub 4}{sup −}) and dichromate (Cr{sub 2}O{sub 7}{sup 2−}) anions in MFCs was hampered by the electrical repulsion between the negatively charged cathode and Cr(VI) functional groups. In contrast, in the presence of Fe(III), the conversion of Cr(VI) and the cathodic coulombic efficiency in the MFCs were 65.6% and 81.7%, respectively, 1.6 times and 1.4 folds as those recorded in the absence of Fe(III). Multiple analytical approaches, including linear sweep voltammetry, Tafel plot, cyclic voltammetry, electrochemical impedance spectroscopy and kinetic calculations demonstrated that the complete reduction of Cr(VI) occurred through an indirect mechanism mediated by Fe(III). The direct reduction of Cr(VI) with cathode electrons in the presence of Fe(III) was insignificant. Fe(III) played a critical role in decreasing both the diffusional resistance of Cr(VI) species and the overpotential for Cr(VI) reduction. This study demonstrated that the reduction of Cr(VI) in MFCs was effective in the presence of Fe(III), providing an alternative and environmentally benign approach for efficient remediation of Cr(VI) contaminated sites with simultaneous production of renewable energy.

Impact of Fe(III) as an effective electron-shuttle mediator for enhanced Cr(VI) reduction in microbial fuel cells: Reduction of diffusional resistances and cathode overpotentials

International Nuclear Information System (INIS)

Wang, Qiang; Huang, Liping; Pan, Yuzhen; Quan, Xie; Li Puma, Gianluca

2017-01-01

Highlights: • Fe(III) shuttles electrons for enhanced reduction of Cr(VI) in MFCs. • The coulombic efficiency increases by 1.6 fold in the presence of Fe(III). • The reduction of Cr(VI) occurs via an indirect Fe(III) mediation mechanism. • Fe(III) decreases the diffusional resistances and the cathode overpotentials. - Abstract: The role of Fe(III) was investigated as an electron-shuttle mediator to enhance the reduction rate of the toxic heavy metal hexavalent chromium (Cr(VI)) in wastewaters, using microbial fuel cells (MFCs). The direct reduction of chromate (CrO_4"−) and dichromate (Cr_2O_7"2"−) anions in MFCs was hampered by the electrical repulsion between the negatively charged cathode and Cr(VI) functional groups. In contrast, in the presence of Fe(III), the conversion of Cr(VI) and the cathodic coulombic efficiency in the MFCs were 65.6% and 81.7%, respectively, 1.6 times and 1.4 folds as those recorded in the absence of Fe(III). Multiple analytical approaches, including linear sweep voltammetry, Tafel plot, cyclic voltammetry, electrochemical impedance spectroscopy and kinetic calculations demonstrated that the complete reduction of Cr(VI) occurred through an indirect mechanism mediated by Fe(III). The direct reduction of Cr(VI) with cathode electrons in the presence of Fe(III) was insignificant. Fe(III) played a critical role in decreasing both the diffusional resistance of Cr(VI) species and the overpotential for Cr(VI) reduction. This study demonstrated that the reduction of Cr(VI) in MFCs was effective in the presence of Fe(III), providing an alternative and environmentally benign approach for efficient remediation of Cr(VI) contaminated sites with simultaneous production of renewable energy.

Correlation between bulk- and surface chemistry of Cr-tanned leather and the release of Cr(III) and Cr(VI).

Science.gov (United States)

Hedberg, Yolanda S; Lidén, Carola; Odnevall Wallinder, Inger

2014-09-15

About 1-3% of the adult general population in Europe is allergic to chromium (Cr). The assessment of the potential release of Cr(III) and Cr(VI) from leather is hence important from a human health and environmental risk perspective. The Cr(VI) content in leather was recently restricted in the European Union. The aim of this study was to assess possible correlations between the bulk and surface chemistry of leather, released Cr(III) and Cr(VI), and capacities of co-released leather specific species to reduce and complex released Cr. Four differently tanned leathers were characterized by scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and the diphenylcarbazide colorimetric method. Their characteristics were compared with results on Cr(III) and Cr(VI) release into artificial sweat (ASW, pHleather-specific species were shown to reduce Cr(VI), both in ASW and in PB. Their reduction capacities correlated with findings of the surface content of Cr and of released Cr. Leather samples without this capacity, and with less aromatic surface groups visible by ATR-FTIR, revealed Cr(VI) both at the surface and in solution (PB). Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Mathematical models applied to the Cr(III) and Cr(VI) breakthrough curves.

Science.gov (United States)

Ramirez C, Margarita; Pereira da Silva, Mônica; Ferreira L, Selma G; Vasco E, Oscar

2007-07-19

Trivalent and hexavalent chromium continuous biosorption was studied using residual brewer Saccharomyces cerevisiae immobilized in volcanic rock. The columns used in the process had a diameter of 4.5 cm and a length of 140 cm, working at an inlet flow rate of 15 mL/min. Breakthrough curves were used to study the yeast biosorption behavior in the process. The saturation time (ts) was 21 and 45 h for Cr(III) and Cr(VI), respectively, and a breakthrough time (tb) of 4 h for Cr(III) and 5 h for Cr(VI). The uptake capacity of the biosorbent for Cr(III) and Cr(VI) were 48 and 60 mg/g, respectively. Two non-diffusional mathematical models with parameters t0 and sigma were used to adjust the experimental data obtained. Microsoft Excel tools were used for the mathematical solution of the two parameters used.

Cr(III) and Cr(VI) in leather and elicitation of eczema

DEFF Research Database (Denmark)

Hansen, Malene Barré; Menne, Torkil; Johansen, Jeanne Duus

2006-01-01

The aim of the present study was to investigate the relation between the content of Cr(VI) and soluble Cr(III) in leather and the ability of the leather to elicit eczema in chromium allergic patients. An array of chromium-tanned leather samples was analysed for the content of total Cr(VI) and sol...

Wavelengths and energy levels of I V and I VI

International Nuclear Information System (INIS)

Kaufman, V.; Sugar, J.; Joshi, Y.N.

1988-01-01

The spectra of iodine were photographed in the 139--1500-Aat;O region on various spectrographs. Earlier analyses of I V and I VI were revised and extended. For I V 26 lines were classified, and for I VI 35 lines were classified. Ionization energies have been estimated to be 415 510 atm≅ 300 cm -1 (51.52 atm≅ 0.04 eV) and 599 800 atm≅ 3 000 cm -1 (74.37 atm≅ 0.37 eV) for I V and I VI, respectively

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

DEFF Research Database (Denmark)

Gammelgaard, Bente; Jøns, O; Nielsen, B

1992-01-01

A method for the simultaneous determination of chromium(iii) and chromium(vi) in a flow system based on chemiluminescence was developed. A Dionex cation-exchange guard column was used to separate chromium(iii) from chromium(vi), and chromium(vi) was reduced by potassium sulfite, whereupon both...

Ferrate(VI) and ferrate(V) oxidation of cyanide, thiocyanate, and copper(I) cyanide

International Nuclear Information System (INIS)

Sharma, Virender K.; Yngard, Ria A.; Cabelli, Diane E.; Clayton Baum, J.

2008-01-01

Cyanide (CN - ), thiocyanate (SCN - ), and copper(I) cyanide (Cu(CN) 4 3- ) are common constituents in the wastes of many industrial processes such as metal finishing and gold mining, and their treatment is required before the safe discharge of effluent. The oxidation of CN - , SCN - , and Cu(CN) 4 3- by ferrate(VI) (Fe VI O 4 2- ; Fe(VI)) and ferrate(V) (Fe V O 4 3- ; Fe(V)) has been studied using stopped-flow and premix pulse radiolysis techniques. The rate laws for the oxidation of cyanides were found to be first-order with respect to each reactant. The second-order rate constants decreased with increasing pH because the deprotonated species, FeO 4 2- , is less reactive than the protonated Fe(VI) species, HFeO 4 - . Cyanides react 10 3 -10 5 times faster with Fe(V) than with Fe(VI). The Fe(V) reaction with CN - proceeds by sequential one-electron reductions from Fe(V) to Fe(IV) to Fe(III). However, a two-electron transfer process from Fe(V) to Fe(III) occurs in the reaction of Fe(V) with SCN - and Cu(CN) 4 3- . The toxic CN - species of cyanide wastes is converted into relatively non-toxic cyanate (NCO - ). Results indicate that Fe(VI) is highly efficient in removing cyanides from electroplating rinse water and gold mill effluent

Biosorption of Cr(VI) by coconut coir: Spectroscopic investigation on the reaction mechanism of Cr(VI) with lignocellulosic material

International Nuclear Information System (INIS)

Shen, Ying-Shuian; Wang, Shan-Li; Huang, Shiuh-Tsuen; Tzou, Yu-Min; Huang, Jang-Hung

2010-01-01

In this study, the removal mechanism of Cr(VI) from water by coconut coir (CC) was investigated using X-ray photoelectron spectroscopy (XPS), Cr K-edge X-ray absorption near edge structure (XANES) and FTIR spectroscopy. The results showed that, upon reaction with CC at pH 3, Cr(VI) was reduced to Cr(III), which was either bound to CC or released back into solution. As revealed by the FTIR spectra of CC before and after reacting with Cr(VI), the phenolic methoxyl and hydroxyl groups of lignin in CC are the dominant drivers of Cr(VI) reduction, giving rise to carbonyl and carboxyl groups on CC. These functional groups can subsequently provide binding sites for Cr(III) resulting from Cr(VI) reduction. In conjunction with forming complexes with carbonyl and carboxyl groups, the formation of Cr(III) hydroxide precipitate could also readily occur as revealed by the linear combination fitting of the Cr K-edge XANES spectrum using a set of reference compounds. The phenolic groups in lignin are responsible for initiating Cr(VI) reduction, so lignocellulosic materials containing a higher amount of phenolic groups are expected to be more effective scavengers for removal of Cr(VI) from the environment.

Biosorption of Cr(VI) by coconut coir: Spectroscopic investigation on the reaction mechanism of Cr(VI) with lignocellulosic material

Energy Technology Data Exchange (ETDEWEB)

Shen, Ying-Shuian [Department of Soil and Environmental Sciences, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 40227, Taiwan (China); Wang, Shan-Li, E-mail: slwang@nchu.edu.tw [Department of Soil and Environmental Sciences, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 40227, Taiwan (China); Huang, Shiuh-Tsuen [Department of Soil and Environmental Sciences, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 40227, Taiwan (China); Department of Science Application and Dissemination, National Taichung University, Taichung, Taiwan (China); Tzou, Yu-Min; Huang, Jang-Hung [Department of Soil and Environmental Sciences, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 40227, Taiwan (China)

2010-07-15

In this study, the removal mechanism of Cr(VI) from water by coconut coir (CC) was investigated using X-ray photoelectron spectroscopy (XPS), Cr K-edge X-ray absorption near edge structure (XANES) and FTIR spectroscopy. The results showed that, upon reaction with CC at pH 3, Cr(VI) was reduced to Cr(III), which was either bound to CC or released back into solution. As revealed by the FTIR spectra of CC before and after reacting with Cr(VI), the phenolic methoxyl and hydroxyl groups of lignin in CC are the dominant drivers of Cr(VI) reduction, giving rise to carbonyl and carboxyl groups on CC. These functional groups can subsequently provide binding sites for Cr(III) resulting from Cr(VI) reduction. In conjunction with forming complexes with carbonyl and carboxyl groups, the formation of Cr(III) hydroxide precipitate could also readily occur as revealed by the linear combination fitting of the Cr K-edge XANES spectrum using a set of reference compounds. The phenolic groups in lignin are responsible for initiating Cr(VI) reduction, so lignocellulosic materials containing a higher amount of phenolic groups are expected to be more effective scavengers for removal of Cr(VI) from the environment.

Biosorption of Cr(VI) by coconut coir: spectroscopic investigation on the reaction mechanism of Cr(VI) with lignocellulosic material.

Science.gov (United States)

Shen, Ying-Shuian; Wang, Shan-Li; Huang, Shiuh-Tsuen; Tzou, Yu-Min; Huang, Jang-Hung

2010-07-15

In this study, the removal mechanism of Cr(VI) from water by coconut coir (CC) was investigated using X-ray photoelectron spectroscopy (XPS), Cr K-edge X-ray absorption near edge structure (XANES) and FTIR spectroscopy. The results showed that, upon reaction with CC at pH 3, Cr(VI) was reduced to Cr(III), which was either bound to CC or released back into solution. As revealed by the FTIR spectra of CC before and after reacting with Cr(VI), the phenolic methoxyl and hydroxyl groups of lignin in CC are the dominant drivers of Cr(VI) reduction, giving rise to carbonyl and carboxyl groups on CC. These functional groups can subsequently provide binding sites for Cr(III) resulting from Cr(VI) reduction. In conjunction with forming complexes with carbonyl and carboxyl groups, the formation of Cr(III) hydroxide precipitate could also readily occur as revealed by the linear combination fitting of the Cr K-edge XANES spectrum using a set of reference compounds. The phenolic groups in lignin are responsible for initiating Cr(VI) reduction, so lignocellulosic materials containing a higher amount of phenolic groups are expected to be more effective scavengers for removal of Cr(VI) from the environment. 2010 Elsevier B.V. All rights reserved.

Analytical applications of N-phenyl-n-butyro hydroxamic and N-p-tolyl-n-butyro hydroxamic acids towards chromium (VI), copper (II), iron (III) and uranium (VI)

International Nuclear Information System (INIS)

Elkhadir, A. Y. F.

2001-05-01

Two aliphatic hydroxamic acids were prepared; N-phenyl-n-butyro hydroxamic acid and N-p-tolyl-n-butyro hydroxamic acid, by the reaction of β-phenylhydroxylamine and p-tolyl hydroxylamine with n-butyryl chloride. The acids were identified by: their melting points, characteristic reactions with acidic solutions of vanadium (V) and iron (III), infrared spectroscopy, nitrogen content and molecular weight determination. The extractability of these acids towards Cr (VI), Cu (II), Fe (III) and U (VI) were investigated at different pH values and molar acid concentrations. N-phenyl-n- butyro hydroxamic acid has a maximum extraction (98.80%) for Cr (VI) at 4 M H 2 SO 4 , (83.25%) for Cu (II) at pH 6, (99.17%) for Fe (III) at pH 5 and (99.76%) at 4 M HNO 3 for U (VI) respectively. N-p-tolyl-n-butyro hydroxamic acid has a maximum extraction (98.40%) for Cr (VI)at 4 M H 2 SO 4 , (81.30%) for Cu (II) at pH 6, (92.80%) for Fe (III) at pH 5 and (99.64%) for U (VI) at 4 M HNO 3 , respectively. The ratios of the metal to ligands were determined by job method (continuous variation method) and were found to be 1:2 for Cr (VI) and U (VI). (Author)

Analytical applications of N-phenyl-n-butyro hydroxamic and N-p-tolyl-n-butyro hydroxamic acids towards chromium (VI), copper (II), iron (III) and uranium (VI)

Energy Technology Data Exchange (ETDEWEB)

Elkhadir, A Y. F. [Department of Chemistry, Faculty of Science, University of Khartoum, Khartoum (Sudan)

2001-05-01

Two aliphatic hydroxamic acids were prepared; N-phenyl-n-butyro hydroxamic acid and N-p-tolyl-n-butyro hydroxamic acid, by the reaction of {beta}-phenylhydroxylamine and p-tolyl hydroxylamine with n-butyryl chloride. The acids were identified by: their melting points, characteristic reactions with acidic solutions of vanadium (V) and iron (III), infrared spectroscopy, nitrogen content and molecular weight determination. The extractability of these acids towards Cr (VI), Cu (II), Fe (III) and U (VI) were investigated at different pH values and molar acid concentrations. N-phenyl-n- butyro hydroxamic acid has a maximum extraction (98.80%) for Cr (VI) at 4 M H{sub 2}SO{sub 4}, (83.25%) for Cu (II) at pH 6, (99.17%) for Fe (III) at pH 5 and (99.76%) at 4 M HNO{sub 3} for U (VI) respectively. N-p-tolyl-n-butyro hydroxamic acid has a maximum extraction (98.40%) for Cr (VI)at 4 M H{sub 2} SO{sub 4}, (81.30%) for Cu (II) at pH 6, (92.80%) for Fe (III) at pH 5 and (99.64%) for U (VI) at 4 M HNO{sub 3}, respectively. The ratios of the metal to ligands were determined by job method (continuous variation method) and were found to be 1:2 for Cr (VI) and U (VI). (Author)

Subtle interactions and electron transfer between U{sup III}, Np{sup III}, or Pu{sup III} and uranyl mediated by the oxo group

Energy Technology Data Exchange (ETDEWEB)

Arnold, Polly L.; Zegke, Markus; Hollis, Emmalina; Pecharman, Anne-Frederique; Love, Jason B. [EaStCHEM School of Chemistry, University of Edinburgh (United Kingdom); Dutkiewicz, Michal S. [EaStCHEM School of Chemistry, University of Edinburgh (United Kingdom); European Commission, Directorate for Nuclear Safety and Security, Joint Research Centre, Karlsruhe (Germany); Walter, Olaf; Apostolidis, Christos; Magnani, Nicola; Griveau, Jean-Christophe; Colineau, Eric; Caciuffo, Roberto [European Commission, Directorate for Nuclear Safety and Security, Joint Research Centre, Karlsruhe (Germany); Zhang, Xiaobin; Schreckenbach, Georg [Department of Chemistry, University of Manitoba, Winnipeg, MB (Canada)

2016-10-04

A dramatic difference in the ability of the reducing An{sup III} center in AnCp{sub 3} (An=U, Np, Pu; Cp=C{sub 5}H{sub 5}) to oxo-bind and reduce the uranyl(VI) dication in the complex [(UO{sub 2})(THF)(H{sub 2}L)] (L=''Pacman'' Schiff-base polypyrrolic macrocycle), is found and explained. These are the first selective functionalizations of the uranyl oxo by another actinide cation. At-first contradictory electronic structural data are explained by combining theory and experiment. Complete one-electron transfer from Cp{sub 3}U forms the U{sup IV}-uranyl(V) compound that behaves as a U{sup V}-localized single molecule magnet below 4 K. The extent of reduction by the Cp{sub 3}Np group upon oxo-coordination is much less, with a Np{sup III}-uranyl(VI) dative bond assigned. Solution NMR and NIR spectroscopy suggest Np{sup IV}U{sup V} but single-crystal X-ray diffraction and SQUID magnetometry suggest a Np{sup III}-U{sup VI} assignment. DFT-calculated Hirshfeld charge and spin density analyses suggest half an electron has transferred, and these explain the strongly shifted NMR spectra by spin density contributions at the hydrogen nuclei. The Pu{sup III}-U{sup VI} interaction is too weak to be observed in THF solvent, in agreement with calculated predictions. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Subtle interactions and electron transfer between UIII, NpIII, or PuIII and uranyl mediated by the oxo group

International Nuclear Information System (INIS)

Arnold, Polly L.; Zegke, Markus; Hollis, Emmalina; Pecharman, Anne-Frederique; Love, Jason B.; Dutkiewicz, Michal S.; Walter, Olaf; Apostolidis, Christos; Magnani, Nicola; Griveau, Jean-Christophe; Colineau, Eric; Caciuffo, Roberto; Zhang, Xiaobin; Schreckenbach, Georg

2016-01-01

A dramatic difference in the ability of the reducing An III center in AnCp 3 (An=U, Np, Pu; Cp=C 5 H 5 ) to oxo-bind and reduce the uranyl(VI) dication in the complex [(UO 2 )(THF)(H 2 L)] (L=''Pacman'' Schiff-base polypyrrolic macrocycle), is found and explained. These are the first selective functionalizations of the uranyl oxo by another actinide cation. At-first contradictory electronic structural data are explained by combining theory and experiment. Complete one-electron transfer from Cp 3 U forms the U IV -uranyl(V) compound that behaves as a U V -localized single molecule magnet below 4 K. The extent of reduction by the Cp 3 Np group upon oxo-coordination is much less, with a Np III -uranyl(VI) dative bond assigned. Solution NMR and NIR spectroscopy suggest Np IV U V but single-crystal X-ray diffraction and SQUID magnetometry suggest a Np III -U VI assignment. DFT-calculated Hirshfeld charge and spin density analyses suggest half an electron has transferred, and these explain the strongly shifted NMR spectra by spin density contributions at the hydrogen nuclei. The Pu III -U VI interaction is too weak to be observed in THF solvent, in agreement with calculated predictions. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Microbial reductive transformation of phyllosilicate Fe(III) and U(VI) in fluvial subsurface sediments.

Science.gov (United States)

Lee, Ji-Hoon; Fredrickson, James K; Kukkadapu, Ravi K; Boyanov, Maxim I; Kemner, Kenneth M; Lin, Xueju; Kennedy, David W; Bjornstad, Bruce N; Konopka, Allan E; Moore, Dean A; Resch, Charles T; Phillips, Jerry L

2012-04-03

The microbial reduction of Fe(III) and U(VI) was investigated in shallow aquifer sediments collected from subsurface flood deposits near the Hanford Reach of the Columbia River in Washington State. Increases in 0.5 N HCl-extractable Fe(II) were observed in incubated sediments and (57)Fe Mössbauer spectroscopy revealed that Fe(III) associated with phyllosilicates and pyroxene was reduced to Fe(II). Aqueous uranium(VI) concentrations decreased in subsurface sediments incubated in sulfate-containing synthetic groundwater with the rate and extent being greater in sediment amended with organic carbon. X-ray absorption spectroscopy of bioreduced sediments indicated that 67-77% of the U signal was U(VI), probably as an adsorbed species associated with a new or modified reactive mineral phase. Phylotypes within the Deltaproteobacteria were more common in Hanford sediments incubated with U(VI) than without, and in U(VI)-free incubations, members of the Clostridiales were dominant with sulfate-reducing phylotypes more common in the sulfate-amended sediments. These results demonstrate the potential for anaerobic reduction of phyllosilicate Fe(III) and sulfate in Hanford unconfined aquifer sediments and biotransformations involving reduction and adsorption leading to decreased aqueous U concentrations.

Ce(III), Th(IV) and U(VI) chelates of alizarin viridine, alizarin heliotrope and alizarin maroon

International Nuclear Information System (INIS)

Idriss, K.A.; Issa, I.M.; Seleim, M.M.

1977-01-01

The complexes of 7,8-dihydroxy-1,4-di(2'-sulpho-4' methylanilino)-anthraquinone (alizarin viridine); 1,4-dihydroxy-2(2'-sulpho-4'-methylanilino)anthraquinone (alizarin heliotrope) and 3-amino-1,2-dihydroxyanthraquinone (alizarin maroon) with Ce(III), and U(VI) have been investigated using spectrophotometric and conductometric methods. The study revealed the formation of complexes having the metal: ligand ratios 1:1 and 1:2. The mean values of logβ (β being stability constant) for the different complexes are determined. The structure of the ligands in the solid chelates were studied by i.r. spectrophotmetry which showed that chelate formation takes place through the C=O and neighbouring OH group and leads to proton displacement. (author)

Microbial Precipitation of Cr(III)-Hydroxide and Se(0) Nanoparticles During Anoxic Bioreduction of Cr(VI)- and Se(VI)-Contaminated Water.

Science.gov (United States)

Kim, Yumi; Oh, Jong-Min; Roh, Yul

2017-04-01

This study examined the microbial precipitations of Cr(III)-hydroxide and Se(0) nanoparticles during anoxic bioreductions of Cr(VI) and Se(VI) using metal-reducing bacteria enriched from groundwater. Metal-reducing bacteria enriched from groundwater at the Korea Atomic Energy Research Institute (KAERI) Underground Research Tunnel (KURT), Daejeon, S. Korea were used. Metal reduction and precipitation experiments with the metal-reducing bacteria were conducted using Cr(VI)- and Se(VI)-contaminated water and glucose as a carbon source under an anaerobic environment at room temperature. XRD, SEM-EDX, and TEM-EDX analyses were used to characterize the mineralogy, crystal structure, chemistry, shape, and size distribution of the precipitates. The metal-reducing bacteria reduced Cr(VI) of potassium chromate (K₂CrO₄) to Cr(III) of chromium hydroxide [Cr(OH)3], and Se(VI) of sodium selenate (Na₂SeO₄) to selenium Se(0), with changes of color and turbidity. XRD, SEM-EDX, and TEM-EDX analyses revealed that the chromium hydroxide [Cr(OH)₃] was formed extracellularly with nanoparticles of 20–30 nm in size, and elemental selenium Se(0) nanoparticles had a sphere shape of 50–250 nm in size. These results show that metal-reducing bacteria in groundwater can aid or accelerate precipitation of heavy metals such as Cr(VI) and Se(VI) via bioreduction processes under anoxic environments. These results may also be useful for the recovery of Cr and Se nanoparticles in natural environments.

Application of double-spike isotope dilution for the accurate determination of Cr(III), Cr(VI) and total Cr in yeast.

Science.gov (United States)

Yang, Lu; Ciceri, Elena; Mester, Zoltán; Sturgeon, Ralph E

2006-11-01

A method is presented for the simultaneous determination of Cr(III) and Cr(VI) in yeast using species-specific double-spike isotope dilution (SSDSID) with anion-exchange liquid chromatography (LC) separation and sector field inductively coupled plasma mass spectrometric (SF-ICP-MS) detection. Total Cr is quantitated using ID SF-ICP-MS. Samples were digested on a hot plate at 95+/-2 degrees C for 6 h in an alkaline solution of 0.5 M NaOH and 0.28 M Na2CO3 for the determination of Cr(III) and Cr(VI), whereas microwave-assisted decomposition with HNO3 and H2O2 was used for the determination of total Cr. Concentrations of 2,014+/-16, 1,952+/-103 and 76+/-48 mg kg-1 (one standard deviation, n=4, 3, 3), respectively were obtained for total Cr, Cr(III) and Cr(VI) in the yeast sample. Significant oxidation of Cr(III) to Cr(VI) (24.2+/-7.6% Cr(III) oxidized, n=3) and reduction of Cr(VI) to Cr(III) (37.6+/-6.5% Cr(VI) reduced, n=3) occurred during alkaline extraction and subsequent chromatographic separation at pH 7. Despite this significant bidirectional redox transformation, quantitative recoveries for both Cr(III) and Cr(VI) were achieved using the SSDSID method. In addition, mass balance between total Cr and the sum of Cr(III) and Cr(VI) concentrations was achieved. Method detection limits of 0.3, 2 and 30 mg kg-1 were obtained for total Cr, Cr(VI) and Cr(III), respectively, based on a 0.2-g sub-sample.

Biliary excretion and distribution of 51Cr(III) and 51Cr(VI) in rats

International Nuclear Information System (INIS)

Cikrt, M.; Bencko, V.

1979-01-01

The biliary excretion and distribution of 51 Cr after intravenous administration of 51 Cr(III) ( 51 CrCl 3 ) or 51 Cr(VI) (Na 2 51 CrO 4 .4H 2 O) were studied in rats. The cumulative biliary excretion of 51 Cr 24 hrs after the injection was significantly higher after administration of 51 Cr(VI) than of 51 Cr(III) (3.51+-0.7% and 0.51+-0.05% of administered dose, respectively). This difference was especially due to a higher rate of biliary excretion of 51 Cr in the first hours after 51 Cr(VI) administration. The excretion of 51 Cr via feces was also higher after administration of 51 Cr(VI) (7.35+-0.45%) of administered dose, as against 4.23+-0.23% after 51 Cr(III). On the other hand, no significant difference in urinary excretion of 51 Cr was found. Statistically significant differences were also observed in the distribution of 51 Cr in the organism after administration of both valence states of the metal. (author)

Bioaccumulation and subcellular partitioning of Cr(III) and Cr(VI) in the freshwater green alga Chlamydomonas reinhardtii

Energy Technology Data Exchange (ETDEWEB)

Aharchaou, Imad [Laboratoire Interdisciplinaire des Environnements Continentaux, UMR 7360, Université de Lorraine and CNRS, 8 rue du Général Delestraint, 57070 Metz (France); Rosabal, Maikel; Liu, Fengjie [Institut National de la Recherche Scientifique, Centre Eau Terre Environnement (INRS-ETE), 490 rue de la Couronne, Québec (Québec) G1K 9A9 (Canada); Battaglia, Eric; Vignati, Davide A.L. [Laboratoire Interdisciplinaire des Environnements Continentaux, UMR 7360, Université de Lorraine and CNRS, 8 rue du Général Delestraint, 57070 Metz (France); Fortin, Claude, E-mail: claude.fortin@ete.inrs.ca [Institut National de la Recherche Scientifique, Centre Eau Terre Environnement (INRS-ETE), 490 rue de la Couronne, Québec (Québec) G1K 9A9 (Canada)

2017-01-15

Highlights: • C. reinhardtii accumulated similar levels of Cr(III) and Cr(VI). • The subcellular partitioning of Cr(III) and Cr(VI) was similar. • Cr(III) and Cr(VI) associated mainly with organelles and heat-stable proteins. • Metallomic analysis showed two main Cr-binding biomolecules after 72 h of exposure. - Abstract: Chromium occurs in aquatic environments under two main redox forms, namely Cr(III) and Cr(VI), with different geochemical and biochemical properties. Cr(VI) readily crosses biological membranes of living organisms and once inside the cells it undergoes a rapid reduction to Cr(III). The route of entry for the latter form is, however, poorly known. Using the radioactive tracer {sup 51}Cr we compared the accumulation (absorption and adsorption) of the two Cr forms by the green unicellular alga Chlamydomonas reinhardii after 1 h and 72 h of exposure to 100 nM of either Cr(III) or Cr(VI) at pH 7. Both Cr forms had similar accumulation, with a major part in the extracellular (adsorbed) fraction after 1 h and a major part of total accumulated Cr in the intracellular (absorbed) fraction after 72 h. We also investigated the intracellular partitioning of Cr using an operational fractionation scheme and found that both Cr forms had similar distributions among fractions: Cr was mostly associated with organelles (23 ± 12% after 1 h and 37 ± 7% after 72 h) and cytosolic heat-stable proteins and peptides (39 ± 18% after 1 h and 35 ± 3% after 72 h) fractions. Further investigations using a metallomic approach (SEC-ICP-MS) were performed with the heat-stable proteins and peptides fraction to compare the distribution of the two Cr forms among various biomolecules of this fraction. One Cr-binding biomolecule (∼28 kDa) appeared after 1 h of exposure for both Cr species. After 72 h another biomolecule of lower molecular weight (∼0.7 kDa) was involved in binding Cr and higher signal intensities were observed for Cr(VI) than for Cr(III). We show, for the

Bioaccumulation and subcellular partitioning of Cr(III) and Cr(VI) in the freshwater green alga Chlamydomonas reinhardtii

International Nuclear Information System (INIS)

Aharchaou, Imad; Rosabal, Maikel; Liu, Fengjie; Battaglia, Eric; Vignati, Davide A.L.; Fortin, Claude

2017-01-01

Highlights: • C. reinhardtii accumulated similar levels of Cr(III) and Cr(VI). • The subcellular partitioning of Cr(III) and Cr(VI) was similar. • Cr(III) and Cr(VI) associated mainly with organelles and heat-stable proteins. • Metallomic analysis showed two main Cr-binding biomolecules after 72 h of exposure. - Abstract: Chromium occurs in aquatic environments under two main redox forms, namely Cr(III) and Cr(VI), with different geochemical and biochemical properties. Cr(VI) readily crosses biological membranes of living organisms and once inside the cells it undergoes a rapid reduction to Cr(III). The route of entry for the latter form is, however, poorly known. Using the radioactive tracer "5"1Cr we compared the accumulation (absorption and adsorption) of the two Cr forms by the green unicellular alga Chlamydomonas reinhardii after 1 h and 72 h of exposure to 100 nM of either Cr(III) or Cr(VI) at pH 7. Both Cr forms had similar accumulation, with a major part in the extracellular (adsorbed) fraction after 1 h and a major part of total accumulated Cr in the intracellular (absorbed) fraction after 72 h. We also investigated the intracellular partitioning of Cr using an operational fractionation scheme and found that both Cr forms had similar distributions among fractions: Cr was mostly associated with organelles (23 ± 12% after 1 h and 37 ± 7% after 72 h) and cytosolic heat-stable proteins and peptides (39 ± 18% after 1 h and 35 ± 3% after 72 h) fractions. Further investigations using a metallomic approach (SEC-ICP-MS) were performed with the heat-stable proteins and peptides fraction to compare the distribution of the two Cr forms among various biomolecules of this fraction. One Cr-binding biomolecule (∼28 kDa) appeared after 1 h of exposure for both Cr species. After 72 h another biomolecule of lower molecular weight (∼0.7 kDa) was involved in binding Cr and higher signal intensities were observed for Cr(VI) than for Cr(III). We show, for the

11-year field study of Pu migration from Pu III, IV, and VI sources

International Nuclear Information System (INIS)

Kaplan, D.I.; Serkiz, S.M.; Demirkanli, D.I.; Gumapas, L.; Fjeld, R.A.; Molz, F.J.; Powell, B.A.

2005-01-01

Full text of publication follows: Understanding the processes controlling Pu mobility in the subsurface environment is important for estimating the amount of Pu waste that can be safely disposed in vadose zone burial sites. To study long-term Pu mobility, four 52-L lysimeters filled with sediment collected from the Savannah River Site near Aiken South Carolina were amended with well characterized solid Pu sources (Pu III Cl 3 , Pu IV (NO 3 ) 4 , Pu IV (C 2 O 4 ) 2 , and Pu VI O 2 (NO 3 ) 2 ) and left exposed to natural precipitation for 2 to 11 years. Pu oxidation state distribution in the Pu(III) and Pu(IV) lysimeters sediments (a red clayey sediment, pH = 6.3) were similar, consisting of 0% Pu(III), >92% Pu(IV), 1% Pu(V), 1% Pu(VI), and the remainder was a Pu polymer. These three lysimeters also had near identical sediment Pu concentration profiles, where >95% of the Pu remained within 1.25 cm of the source after 11 years; moving at an overall rate of 0.9 cm yr -1 . As expected, Pu moved more rapidly through the Pu(VI) lysimeter, at an overall rate of 12.5 cm yr -1 . Solute transport modeling of the sediment Pu concentration profile data in the Pu(VI) lysimeter indicated that some transformation of Pu into a much less mobile form, presumably Pu(IV), had occurred during the course of the two year study. This modeling also supported previous laboratory measurements showing that Pu(V) or Pu(VI) reduction was five orders of magnitude faster than corresponding Pu(III) or Pu(IV) oxidation. The slow oxidation rate (1 x 10-8 hr -1 ; t 1/2 = 8,000 yr) was not discernable from the Pu(VI) lysimeter data that reflected only two years of transport but was readily discernable from the Pu(III) and Pu(IV) lysimeter data that reflected 11 yr of transport. (authors)

Biomonitoring chromium III or VI soluble pollution by moss chlorophyll fluorescence.

Science.gov (United States)

Chen, Yang-Er; Mao, Hao-Tian; Ma, Jie; Wu, Nan; Zhang, Chao-Ming; Su, Yan-Qiu; Zhang, Zhong-Wei; Yuan, Ming; Zhang, Huai-Yu; Zeng, Xian-Yin; Yuan, Shu

2018-03-01

We systematically compared the impacts of four Cr salts (chromic chloride, chromic nitrate, potassium chromate and potassium bichromate) on physiological parameters and chlorophyll fluorescence in indigenous moss Taxiphyllum taxirameum. Among the four Cr salts, K 2 Cr 2 O 7 treatment resulted in the most significant decrease in photosynthetic efficiency and antioxidant enzymes, increase in reactive oxygen species (ROS), and obvious cell death. Different form the higher plants, although hexavalent Cr(VI) salt treatments resulted in higher accumulation levels of Cr and were more toxic than Cr(III) salts, Cr(III) also induced significant changes in moss physiological parameters and chlorophyll fluorescence. Our results showed that Cr(III) and Cr(VI) could be monitored distinguishably according to the non-photochemical quenching (NPQ) fluorescence of sporadic purple and sporadic lavender images respectively. Then, the valence states and concentrations of Cr contaminations could be evaluated according to the image of maximum efficiency of PSII photochemistry (Fv/Fm) and the quantum yield of PSII electron transport (ΦPSII). Therefore, this study provides new ideas of moss's sensibility to Cr(III) and a new method to monitor Chromium contaminations rapidly and non-invasively in water. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Reduction of Cr(VI) to Cr(III) by Natural Fe-Bearing Minerals: A Synchrotron XAS Study

Science.gov (United States)

Xu, H.; Guo, X.; Ding, M.; Migdissov, A. A.; Boukhalfa, H.; Sun, C.; Roback, R. C.; Reimus, P. W.; Katzman, D.

2017-12-01

Cr(VI) in the form of CrO42- is a pollutant species in groundwater and soils that can pose health and environmental problems. Cr(VI) associated with use as a corrosion inhibitor at a power plant from 1956-1972 is present in a deep groundwater aquifer at Los Alamos National Laboratory. A potential remediation strategy for the Cr contamination is reduction of Cr(VI) to Cr(III) via the acceptance of electrons from naturally occurring or induced Fe(II) occurring in Fe-bearing minerals. In this work, using synchrotron-based X-ray techniques, we investigated the Cr reduction behavior by Fe-bearing minerals from outcrop and core samples representative of the contaminated portion of the aquifer. Samples were exposed to solutions with a range of known Cr (VI) concentrations. XANES and EXAFS spectra showed that all the Cr(VI) had been reduced to Cr(III), and micro XRF mapping revealed close correlation of Cr and Fe distribution, implying that Fe(II) in minerals reduced Cr(VI) in the solution. Similar behavior was observed from in-situ XANES measurements on Cr reduction and adsorption by mineral separates from the rock samples in Cr(VI)-bearing solutions. In addition, to obtain reference parameters for interpreting the data of natural samples, we collected Cr and Fe EXAFS spectra of Cr(III)-Fe(III) hydroxide solid solutions, which show progressive changes in the local structure around Cr and Fe over the whole series.

Spectrophotometric and potentiometric studies of oxidation of Mo(III) by Mo(VI) in phosphoric acid medium

Energy Technology Data Exchange (ETDEWEB)

Kumar, A; Verma, G S.P. [Ranchi Coll. (India). Dept. of Chemistry

1975-12-01

Oxidation of Mo(III) (green) by Mo(VI) in an inert atmosphere and in orthophosphoric acid medium at various acid concentrations is reported. Potentiometric and spectrophotometric data suggest that oxidation of Mo(III) proceeds to Mo(V) through a binuclear species Mo(III) Mo(IV) absorbing at 400 nm. The formation of this species is facilitated at high acid concentrations. It is further found that quantitative conversion of Mo(III) into Mo(V) takes place at fairly high acid concentrations. In high phosphoric acid concentrations, solution of Mo(III) has been found to be oxidized to Mo(VI) by air and hence this can be used as a good oxygen absorber.

Reduction of Fe(III), Cr(VI), U(VI), and Tc(VII) by Deinococcus radiodurans R1

International Nuclear Information System (INIS)

Fredrickson, J.K.; Kostandarithes, H.M.; Li, S.W.; Plymake, A.E.; Daly, M.J.

2000-01-01

Deinococcus radiodurans is an exceptionally radiation-resistant microorganism capable of surviving acute exposures to ionizing radiation doses of 15,000 Gy and previously described as having a strictly aerobic respiratory metabolism. Under strict anaerobic conditions, D. radiodurans R1 reduced Fe(III)-nitrilotriacetic acid coupled to the oxidation of lactate to CO 2 and acetate but was unable to link this process to growth. D. radiodurans reduced the humic acid analog anthraquinone-2,6-disulfonate (AQDS) to its dihydroquinone form, AH 2 DS, which subsequently transferred electrons to the Fe(III) oxides hydrous ferric oxide and goethite via a previously described electron shuttle mechanism. D. radiodurans reduced the solid-phase Fe(III) oxides in the presence of either 0.1 mM AQDS or leonardite humic acids (2 mg ml -1 ) but not in their absence. D. radiodurans also reduced U(VI) and Tc(VII) in the presence of AQDS. In contrast, Cr(VI) was directly reduced in anaerobic cultures with lactate although the rate of reduction was higher in the presence of AQDS. The results are the first evidence that D. radiodurans can reduce Fe(III) coupled to the oxidation of lactate or other organic compounds. Also, D. radiodurans, in combination with humic acids or synthetic electron shuttle agents, can reduce U and Tc and thus has potential applications for remediation of metal- and radionuclide-contaminated sites where ionizing radiation or other DNA-damaging agents may restrict the activity of more sensitive organisms

Treatment of chemical warfare agents by zero-valent iron nanoparticles and ferrate(VI)/(III) composite

International Nuclear Information System (INIS)

Zboril, Radek; Andrle, Marek; Oplustil, Frantisek; Machala, Libor; Tucek, Jiri; Filip, Jan; Marusak, Zdenek; Sharma, Virender K.

2012-01-01

Highlights: ► Ferrate(VI) has been found to be highly efficient to decontaminate chemical warfare agents. ► Fast degradation of sulfur mustard, soman and compound VX by ferrate(VI). ► Nanoscale zero-valent iron particles are considerably less efficient in degradation of studied warfare agents compared to ferrate(VI). - Abstract: Nanoscale zero-valent iron (nZVI) particles and a composite containing a mixture of ferrate(VI) and ferrate(III) were prepared by thermal procedures. The phase compositions, valence states of iron, and particle sizes of iron-bearing compounds were determined by combination of X-ray powder diffraction, Mössbauer spectroscopy and scanning electron microscopy. The applicability of these environmentally friendly iron based materials in treatment of chemical warfare agents (CWAs) has been tested with three representative compounds, sulfur mustard (bis(2-chlorethyl) sulfide, HD), soman ((3,3′-imethylbutan-2-yl)-methylphosphonofluoridate, GD), and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothiolate (VX). Zero-valent iron, even in the nanodimensional state, had a sluggish reactivity with CWAs, which was also observed in low degrees of CWAs degradation. On the contrary, ferrate(VI)/(III) composite exhibited a high reactivity and complete degradations of CWAs were accomplished. Under the studied conditions, the estimated first-order rate constants (∼10 −2 s −1 ) with the ferrate(VI)/(III) composite were several orders of magnitude higher than those of spontaneous hydrolysis of CWAs (10 −8 –10 −6 s −1 ). The results demonstrated that the oxidative technology based on application of ferrate(VI) is very promising to decontaminate CWAs.

Spectrophotometric and potentiometric studies of oxidation of Mo(III) by Mo(VI) in phosphoric acid medium

International Nuclear Information System (INIS)

Kumar, Arvind; Verma, G.S.P.

1975-01-01

Oxidation of Mo(III) (green) by Mo(VI) in an inert atmosphere and in orthophosphoric acid medium at various acid concentrations is reported. Potentiometric and spectrophotometric data suggest that oxidation of Mo(III) proceeds to Mo(V) through a binuclear species Mo(III) Mo(IV) absorbing at 400 nm. The formation of this species is facilitated at high acid concentrations. It is further found that quantitative conversion of Mo(III) into Mo(V) takes place at fairly high acid concentrations. In high phosphoric acid concentrations, solution of Mo(III) has been found to be oxidized to Mo(VI) by air and hence this can be used as a good oxygen absorber. (author)

Enhanced biotic and abiotic transformation of Cr(vi) by quinone-reducing bacteria/dissolved organic matter/Fe(iii) in anaerobic environment.

Science.gov (United States)

Huang, Bin; Gu, Lipeng; He, Huan; Xu, Zhixiang; Pan, Xuejun

2016-09-14

This study investigated the simultaneous transformation of Cr(vi) via a closely coupled biotic and abiotic pathway in an anaerobic system of quinone-reducing bacteria/dissolved organic matters (DOM)/Fe(iii). Batch studies were conducted with quinone-reducing bacteria to assess the influences of sodium formate (NaFc), electron shuttling compounds (DOM) and the Fe(iii) on Cr(vi) reduction rates as these chemical species are likely to be present in the environment during in situ bioremediation. Results indicated that the concentration of sodium formate and anthraquinone-2-sodium sulfonate (AQS) had apparently an effect on Cr(vi) reduction. The fastest decrease in rate for incubation supplemented with 5 mM sodium formate and 0.8 mM AQS showed that Fe(iii)/DOM significantly promoted the reduction of Cr(vi). Presumably due to the presence of more easily utilizable sodium formate, DOM and Fe(iii) have indirect Cr(vi) reduction capability. The coexisting cycles of Fe(ii)/Fe(iii) and DOM(ox)/DOM(red) exhibited a higher redox function than the individual cycle, and their abiotic coupling action can significantly enhance Cr(vi) reduction by quinone-reducing bacteria.

I-III-VI.sub.2 based solar cell utilizing the structure CuInGaSe.sub.2 CdZnS/ZnO

Science.gov (United States)

Chen, Wen S.; Stewart, John M.

1992-01-07

A thin film I-III-VI.sub.2 based solar cell having a first layer of copper indium gallium selenide, a second layer of cadmium zinc sulfide, a double layer of zinc oxide, and a metallization structure comprised of a layer of nickel covered by a layer of aluminum. An optional antireflective coating may be placed on said metallization structure. The cadmium zinc sulfide layer is deposited by means of an aqueous solution growth deposition process and may actually consist of two layers: a low zinc content layer and a high zinc content layer. Photovoltaic efficiencies of 12.5% at Air Mass 1.5 illumination conditions and 10.4% under AMO illumination can be achieved.

Treatment of chemical warfare agents by zero-valent iron nanoparticles and ferrate(VI)/(III) composite

Energy Technology Data Exchange (ETDEWEB)

Zboril, Radek, E-mail: zboril@prfnw.upol.cz [Regional Centre of Advanced Technologies and Materials, Departments of Physical Chemistry and Experimental Physics, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic); Andrle, Marek; Oplustil, Frantisek [Military Institute VOP-026 Sternberk, Division in Brno, Rybkova 8, 602 00 Brno (Czech Republic); Machala, Libor; Tucek, Jiri; Filip, Jan; Marusak, Zdenek [Regional Centre of Advanced Technologies and Materials, Departments of Physical Chemistry and Experimental Physics, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic); Sharma, Virender K., E-mail: vsharma@fit.edu [Chemistry Department, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901 (United States); Center of Ferrate Excellence, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901 (United States)

2012-04-15

Highlights: Black-Right-Pointing-Pointer Ferrate(VI) has been found to be highly efficient to decontaminate chemical warfare agents. Black-Right-Pointing-Pointer Fast degradation of sulfur mustard, soman and compound VX by ferrate(VI). Black-Right-Pointing-Pointer Nanoscale zero-valent iron particles are considerably less efficient in degradation of studied warfare agents compared to ferrate(VI). - Abstract: Nanoscale zero-valent iron (nZVI) particles and a composite containing a mixture of ferrate(VI) and ferrate(III) were prepared by thermal procedures. The phase compositions, valence states of iron, and particle sizes of iron-bearing compounds were determined by combination of X-ray powder diffraction, Moessbauer spectroscopy and scanning electron microscopy. The applicability of these environmentally friendly iron based materials in treatment of chemical warfare agents (CWAs) has been tested with three representative compounds, sulfur mustard (bis(2-chlorethyl) sulfide, HD), soman ((3,3 Prime -imethylbutan-2-yl)-methylphosphonofluoridate, GD), and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothiolate (VX). Zero-valent iron, even in the nanodimensional state, had a sluggish reactivity with CWAs, which was also observed in low degrees of CWAs degradation. On the contrary, ferrate(VI)/(III) composite exhibited a high reactivity and complete degradations of CWAs were accomplished. Under the studied conditions, the estimated first-order rate constants ({approx}10{sup -2} s{sup -1}) with the ferrate(VI)/(III) composite were several orders of magnitude higher than those of spontaneous hydrolysis of CWAs (10{sup -8}-10{sup -6} s{sup -1}). The results demonstrated that the oxidative technology based on application of ferrate(VI) is very promising to decontaminate CWAs.

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

Science.gov (United States)

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.

Determination of free acid in U(VI)-Al(III) solution by Gran plot titration

International Nuclear Information System (INIS)

Suh, Moo Yul; Lee, Chang Heon; Sohn, Se Chul; Kim, Jung Suk; Kim, Won Ho; Eom, Tae Yoon

1999-01-01

The determination method of free acid in spent U-Al nuclear fuel solutions by Gran plot titration was described. Effect of U(VI) and Al(III) on the alkalimetric titration of nitric acid was investigation in oxalate complexing media as well as in noncomplexing media. Positive biases were observed in both titration media when the end-point was estimated by the Gran plot method. It was found that the cause of the bias was U(VI) in the oxalate complexing media, but Al(III) in the noncomplexing media. The relative error was less than 1% in the titration of 0.1 M HNO 3 at a U(VI):Al(III):H + mole ratio of up to 2:12:1 as long as the pH of the oxalate titration media was sustained to be below 5.0 at the beginning of titration. The method was successfully applied to the determination of nitric acid in a solution of HANARO reactor fuel with U:Al mole ratio of 1:6

Uranyl(VI) and lanthanum(III) complexes with functionalized macrocyclic and macroacyclic Schiff bases

International Nuclear Information System (INIS)

Aguiari, A.; Brianese, N.; Tamburini, S.; Vigato, P.A.

1995-01-01

Acyclic Schiff bases have been prepared by [2 + 1] condensation of 2,6-diformyl-4-chlorophenol and H 2 NCH 2 [CH 2 XCH 2 ] n CH 2 NH 2 (n =3D 0 H 2 -I; X =3D NH, S, O n =3D 1 H 2 -II...H 2 -IV; X =3D 0 n =3D 2 H 2 -V; X =3D 0 n =3D 3 H 2 -VI). The related uranlyl(VI) and lanthanum (III) complexes have bee synthesized by reaction by reaction of the preformed ligands with the appropriate salt or by the template procedure, in the presence of base. No base was employed in the preparation of lanthanum (III) complexes, La(H 2 -II)(NO 3 ) 3 , La(H 2 -IV)(NO 3 ) 3 where the Schiff bases coordinate as neutral chelate ligands. These acyclic complexes have been used for further condensation, and symmetric and asymmetric cyclic complexes have been obtained by their reaction with the polyamines H 2 NCH 2 [CH 2 XCH 2 ]nCH 2 NH 2 or with 4,4'-diaminodibenzo -18-crown-6. By reaction with 4-aminobenzo-15-crown-5 or 2-amino-methyl-15-crown-5, the same acyclic complexes give rise to functionalized complexes bearing crown-ether moieties. Analogously, the acyclic ligand H 3 -IXX, prepared by condensation of 2,6 diformyl-4-chlorophenol and tris(aminoethyl)amine, forms mono and homodinuclear lanthanum (III) complexes, which may undergo further condensation when reacted with primary functionalized amines. (authors). 42 refs., 2 figs., 2 schemes, 1 tab

Diversity of the Germination Apparatus in Clostridium botulinum Groups I, II, III and IV

Directory of Open Access Journals (Sweden)

Jason Brunt

2016-10-01

Full Text Available Clostridium botulinum is a highly dangerous pathogen that forms very resistant endospores that are ubiquitous in the environment, and which, under favourable conditions germinate to produce vegetative cells that multiply and form the exceptionally potent botulinum neurotoxin. To improve the control of botulinum neurotoxin-forming clostridia, it is important to understand the mechanisms involved in spore germination. Here we present models for spore germination in C. botulinum based on comparative genomics analyses, with C. botulinum Groups I and III sharing similar pathways, which differ from those proposed for C. botulinum Groups II and IV. All spores germinate in response to amino acids interacting with a germinant receptor, with four types of germinant receptor identified (encoded by various combinations of gerA, gerB and gerC genes (gerX. There are three gene clusters with an ABC-like configuration; ABC gerX1, ABABCB gerX2 and ACxBBB gerX4, and a single CA-B gerX3 gene cluster. Subtypes have been identified for most germinant receptors types, and the individual GerX subunits of each cluster show similar grouping in phylogenetic trees. C. botulinum Group I contained the largest variety of gerX subtypes, with three gerX1, three gerX2 and one gerX3 subtypes, while C. botulinum Group III contained two gerX1 types and one gerX4. C. botulinum Groups II and IV contained a single germinant receptor, gerX3 and gerX1, respectively. It is likely that all four C. botulinum Groups include a SpoVA channel involved in DPA release. The cortex lytic enzymes present in C. botulinum Groups I and III appear to be CwlJ and SleB, while in C. botulinum Groups II and IV, SleC appears to be important.

Reductive immobilization of U(VI) in Fe(III) oxide-reducing subsurface sediments: Analysis of coupled microbial-geochemical processes in experimental reactive transport systems. Final Scientific/Technical Report-EMSP 73914

International Nuclear Information System (INIS)

Eric E. Roden Matilde M. Urrutia Mark O. Barnett Clifford R. Lange

2005-01-01

) reduction is likely to be less efficient in natural soils and sediments than would be inferred from studies with synthetic Fe(III) oxides. A key implication of these findings is that production of Fe(II)-enriched sediments during one-time (or periodic) stimulation of DMRB activity is not likely to permit efficient long-term abiotic conversion of U(VI) to U(IV) in biogenic redox barriers designed to prevent far-field subsurface U(VI) migration. Instead our results suggest that ongoing DMRB activity will be required to achieve maximal U(VI) reduction efficiency, and emphasize the need for detailed understanding of patterns of DMRB growth, colonization, and maintenance in physically and chemically heterogeneous subsurface environments in order to predict the effectiveness of subsurface U(VI) bioremediation operations. A final ''capstone'' aspect of experimental work on the project was to examine the potential for sustained coupled Fe(III) oxide and U(VI) reduction in experimental flow-through reactor systems (i.e. sediment columns and ''semicontinuous culture'' systems) that are conceptually analogous to hydrologically-open subsurface environments. The results conclusively demonstrated the potential for sustained removal of U(VI) from solution via DMRB activity in excess of the U(VI) sorption capacity of the natural mineral assemblages as determined in abiotic controls. In addition, the abundance of sorbed U(VI) (a potential long-term source of U(VI) to the aqueous phase) was much lower in the biotic vs. abiotic systems. The latter results agree with other project findings which demonstrated the capacity for G. sulfurreducens to reduce sorbed U(VI). Throughout the project we have developed and refined a variety of reaction-based models of coupled Fe(III) oxide/U(VI) reduction, including a generalized model which accounts for the population dynamics of various respiratory microbial functional groups. These models have been employed in numerical simulations of both batch bench

Outbreeding lethality between toxic Group I and nontoxic Group III Alexandrium tamarense spp. isolates: Predominance of heterotypic encystment and implications for mating interactions and biogeography

Science.gov (United States)

Brosnahan, Michael L.; Kulis, David M.; Solow, Andrew R.; Erdner, Deana L.; Percy, Linda; Lewis, Jane; Anderson, Donald M.

2010-02-01

We report the zygotic encystment of geographically dispersed isolates in the dinoflagellate species complex Alexandrium tamarense, in particular, successful mating of toxic Group I and nontoxic Group III isolates. However, hypnozygotes produced in Group I/III co-cultures complete no more than three divisions after germinating. Previous reports have suggested a mate recognition mechanism whereby hypnozygotes produced in co-cultures could arise from either homotypic (inbred) or heterotypic (outbred) gamete pairs. To determine the extent to which each occurs, a nested PCR assay was developed to determine parentage of individual hypnozygotes. The vast majority of hypnozygotes from pairwise Group I/III co-cultures were outbred, so that inviability was a result of hybridization, not inbreeding. These findings support the assertion that complete speciation underlies the phylogenetic structure of the Alexandrium tamarense species complex. Additionally, the ribosomal DNA (rDNA) copy numbers of both hybrid and single ribotype hypnozygotes were reduced substantially from those of haploid motile cells. The destruction of rDNA loci may be crucial for the successful mating of genetically distant conjugants and appears integral to the process of encystment. The inviability of Group I/III hybrids is important for public health because the presence of hybrid cysts may indicate ongoing displacement of a nontoxic population by a toxic one (or vice versa). Hybrid inviability also suggests a bloom control strategy whereby persistent, toxic Group I blooms could be mitigated by introduction of nontoxic Group III cells. The potential for hybridization in nature was investigated by applying the nested PCR assay to hypnozygotes from Belfast Lough, Northern Ireland, a region where Group I and III populations co-occur. Two hybrid cysts were identified in 14 successful assays, demonstrating that Group I and III populations do interbreed in that region. However, an analysis of mating data

Reduction of Cr(VI) to Cr(III) using silicon nanowire arrays under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Fellahi, Ouarda [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); Centre de Recherche en Technologie des Semi-conducteurs pour l' Energétique-CRTSE 02, Bd Frantz Fanon, BP. 140, Alger 7 Merveilles (Algeria); Barras, Alexandre [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); Pan, Guo-Hui [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 3888 Dong Nanhu Road, Changchun 130033 (China); Coffinier, Yannick [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); Hadjersi, Toufik [Centre de Recherche en Technologie des Semi-conducteurs pour l' Energétique-CRTSE 02, Bd Frantz Fanon, BP. 140, Alger 7 Merveilles (Algeria); Maamache, Mustapha [Laboratoire de Physique Quantique et Systèmes Dynamiques, Département de Physique, Université de Sétif, Sétif 19000 (Algeria); Szunerits, Sabine [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); and others

2016-03-05

Highlights: • Cr(VI) reduction to Cr(III) using silicon nanowires decorated with Cu nanoparticles. • The reduction takes place at room temperature and neutral pH under visible light. • The photocatalytic reduction was enhanced by addition of adipic or citric acid. - Abstract: We report an efficient visible light-induced reduction of hexavalent chromium Cr(VI) to trivalent Cr(III) by direct illumination of an aqueous solution of potassium dichromate (K{sub 2}Cr{sub 2}O{sub 7}) in the presence of hydrogenated silicon nanowires (H-SiNWs) or silicon nanowires decorated with copper nanoparticles (Cu NPs-SiNWs) as photocatalyst. The SiNW arrays investigated in this study were prepared by chemical etching of crystalline silicon in HF/AgNO{sub 3} aqueous solution. The Cu NPs were deposited on SiNW arrays via electroless deposition technique. Visible light irradiation of an aqueous solution of K{sub 2}Cr{sub 2}O{sub 7} (10{sup −4} M) in presence of H-SiNWs showed that these substrates were not efficient for Cr(VI) reduction. The reduction efficiency achieved was less than 10% after 120 min irradiation at λ > 420 nm. Addition of organic acids such as citric or adipic acid in the solution accelerated Cr(VI) reduction in a concentration-dependent manner. Interestingly, Cu NPs-SiNWs was found to be a very efficient interface for the reduction of Cr(VI) to Cr(III) in absence of organic acids. Almost a full reduction of Cr(VI) was achieved by direct visible light irradiation for 140 min using this photocatalyst.

Imaging of Cranial Nerves III, IV, VI in Congenital Cranial Dysinnervation Disorders.

Science.gov (United States)

Kim, Jae Hyoung; Hwang, Jeong Min

2017-06-01

Congenital cranial dysinnervation disorders are a group of diseases caused by abnormal development of cranial nerve nuclei or their axonal connections, resulting in aberrant innervation of the ocular and facial musculature. Its diagnosis could be facilitated by the development of high resolution thin-section magnetic resonance imaging. The purpose of this review is to describe the method to visualize cranial nerves III, IV, and VI and to present the imaging findings of congenital cranial dysinnervation disorders including congenital oculomotor nerve palsy, congenital trochlear nerve palsy, Duane retraction syndrome, Möbius syndrome, congenital fibrosis of the extraocular muscles, synergistic divergence, and synergistic convergence. © 2017 The Korean Ophthalmological Society.

Synovial sarcoma with relevant immunocytochemistry and special emphasis on the monophasic fibrous variant

Directory of Open Access Journals (Sweden)

Kottu Radhika

2010-01-01

Full Text Available Background: Monophasic fibrous synovial sarcoma (SS is the most common variant of SS. Only a few cytological studies are available on this entity. Bcl-2 protein expression has been described as a characteristic marker of SS and is useful for its differentiation from other sarcomas. Cytokeratin and CD99 are also used in detecting SS. Aims: To evaluate synovial sarcoma and its variants cytomorphologically. Materials and Methods: During a period of 10 years 7 months, i.e. from January 1998 to July 2008, 12 cytologic specimens diagnosed as synovial sarcoma were reviewed. Ten cases were diagnosed as SS on aspiration alone but two cases required ancillary technique i.e., immunocytochemistry staining with bcl-2 and cytokeratin. The smears were stained with Papanicolaou and May-Grόnwald-Giemsa stains. Results: All cytologic specimens in our study had similar appearance. Most smears were highly cellular and were made up of densely packed tri-dimensional groups and singly scattered round to oval cells. Cellular monomorphism and vascular channels within the cell groups were the remarkable findings. Only one case showed cytologic evidence of epithelial differentiation. Bcl-2, cytokeratin, CD99 positivity was seen on immunohistochemistry staining. Results were categorized according to age, sex and morphologic variants. Conclusions: Although cytomorphologic features of synovial sarcomas are characteristic enough to permit its recognition, clinical correlation is necessary for accurate diagnosis. Monophasic variant is the most common entity observed in the present study.

Cranial nerves III, IV and VI

International Nuclear Information System (INIS)

Laine, I.J.; Smoker, W.R.; Kuta, A.J.; Felton, W.L.

1991-01-01

Because of advances in CT and MR imaging, accurate identification and evaluation of cranial nerve lesions is now possible. Cranial nerves III, IV, and VI, providing motor and sensory control of the eye, can be evaluated as a unit. In this paper, the authors present an overview of the anatomy and pathology of these cranial nerves. We first illustrate their normal anatomic pathways from the brain stem to the orbit. This is followed by clinical examples of patients with a variety of isolated and complex palsies of these three cranial nerves. This is accomplished by inclusion of ocular photographs, correlative imaging studies, and the use of diagrams. Knowledge of the gross and imaging anatomy and the ophthalmologic manifestations of pathology affecting these three cranial nerves permits a tailored approach to their evaluation

Construction of monophase nets

International Nuclear Information System (INIS)

Suarez A, Jose Antonio

1996-01-01

The paper refers to the use of monophase loads in commercial residential urbanizations and in small industries, for this reason it is considered unnecessary the construction of three-phase nets. The author makes a historical recount of these nets in Bogota, his capacities, uses and energy savings

Ordered perovskites with cationic vacancies. 4. Compounds of type Ba/sub 6/B/sub 2/sup(III)vacantTe/sub 3/sup(VI)O/sub 18/

Energy Technology Data Exchange (ETDEWEB)

Schittenhelm, H J; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1979-07-01

Compounds of the composition Ba/sub 6/B(III)/sub 2/vacantTe(VI)/sub 3/O/sub 18/ equivalent to Ba/sub 2/Ba(III)sub(2/3)vacantsub(1/3)Te(VI)O/sub 6/, with B(III) = Pr, Nd, Sm-Lu, Y crystallize with a cubic perovskite lattice. The cell parameters diminish as the size of B(III) falls (B(III) = Pr: a = 8.52 A; Lu: a = 8.33 A). In contrast to the corresponding perovskites with U(VI) and W(VI) no polymorphism is observed.

Spectrophotometric determination of uranium (VI) with arsenazo III in a nitric medium

International Nuclear Information System (INIS)

Yamaura, Mitiko; Wada, Luciana Yukie; Ribeiro, Fernando Castilho

2002-01-01

Arsenazo III is an organic reagent usually used for the photometric determination of various elements, including the uranium, thorium, plutonium, barium, strontium, hafnium, bismuth and the rare earth elements. The reactions of arsenazo III with many elements are very sensitive and, consequently is not specific for any element. Arsenazo III with U(VI) gives a 1:1 coloured complex in diluted acid solution of pH 1 to 3, and in strong acid media forming 1:1, 1:2 and 1:3 species. In this work, a detailed study of the influence of pH is described. The stability of formed complex and the interference of Fe(III) ions were also studied. (author)

The potential impact of microbial Fe(III) reduction on subsurface U(VI) mobility at a low level radioactive waste storage site

International Nuclear Information System (INIS)

Wilkins, M.J.; Livens, F.R.; Vaughan, D.J.; Lloyd, J.R.; Beadle, I.; Small, J.S.

2005-01-01

Full text of publication follows: Fe(III) oxy-hydroxides have the potential to be utilised as terminal electron acceptors by indigenous microbial communities in the British Nuclear Fuels (BNFL) low level radioactive waste storage site at Drigg (Cumbria, UK) and these organisms may have a critical control on the biogeochemical cycling of several environmentally important radionuclides. In terms of radiological impact at Drigg, uranium is the most significant contributor to radiological impact and it is strongly influenced by biogeochemical processes. In terms of mass (moles) it is also the most abundant radionuclide in the Drigg inventory. Thus, the potential biotic and abiotic effects of Fe(III) reduction on U(VI) mobility in the Drigg subsurface are of interest. Culture-dependent and molecular techniques showed that the sediments in and around the Drigg site contained a diversity of Fe(III)-reducing bacteria. A series of microcosm experiments were utilised to create environmentally relevant experimental conditions. Microcosms set up using Drigg sediment and synthetic ground water were spiked with 100 μM U(VI) and acetate as an electron donor. U(VI) concentrations in groundwater were measured using a chemical assay while total U levels were determined using ICP-MS. Fe(II) levels were determined using the ferrozine method. Sediment surface areas were measured using BET analysis. The low surface area of the sediments resulted in only a small proportion of the 100 μM U(VI) spike sorbing onto mineral surfaces. The addition of ferri-hydrite to some microcosms resulted in an immediate lowering of soluble U(VI) concentrations, suggesting that the formation of soluble U(VI) complexes were not responsible for the minimal adsorption. The presence of biogenic Fe(II) in the microcosms did not affect the soluble U(VI) concentration. Similarly, soluble U(VI) levels remained unchanged when sediments were spiked with U(VI) post-microbial Fe(III) reduction. However, a lowering in

Influence of Reactive Transport on the Reduction of U(VI) in the Presence of Fe(III) and Nitrate: Implications for U(VI) Immobilization by Bioremediation/Biobarriers - Final Report

International Nuclear Information System (INIS)

B.D. Wood

2007-01-01

Subsurface contamination by metals and radionuclides represent some of the most challenging remediation problems confronting the Department of Energy (DOE) complex. In situ remediation of these contaminants by dissimilatory metal reducing bacteria (DMRB) has been proposed as a potential cost effective remediation strategy. The primary focus of this research is to determine the mechanisms by which the fluxes of electron acceptors, electron donors, and other species can be controlled to maximize the transfer of reductive equivalents to the aqueous and solid phases. The proposed research is unique in the NABIR portfolio in that it focuses on (i) the role of flow and transport in the initiation of biostimulation and the successful sequestration of metals and radionuclides [specifically U(VI)], (ii) the subsequent reductive capacity and stability of the reduced sediments produced by the biostimulation process, and (iii) the potential for altering the growth of biomass in the subsurface by the addition of specific metabolic uncoupling compounds. A scientifically-based understanding of these phenomena are critical to the ability to design successful bioremediation schemes. The laboratory research will employ Shewanella putrefaciens (CN32), a facultative DMRB that can use Fe(III) oxides as a terminal electron acceptor. Sediment-packed columns will be inoculated with this organism, and the reduction of U(VI) by the DMRB will be stimulated by the addition of a carbon and energy source in the presence of Fe(III). Separate column experiments will be conducted to independently examine: (1) the importance of the abiotic reduction of U(VI) by biogenic Fe(II); (2) the influence of the transport process on Fe(III) reduction and U(VI) immobilization, with emphasis on methods for controlling the fluxes of aqueous species to maximize uranium reduction; (3) the reductive capacity of biologically-reduced sediments (with respect to re-oxidation by convective fluxes of O2 and NO3-) and

Articulación de fones en individuos clase esqueletal I,II y III Speech patterns in skeletal class I, II and III subjects

Directory of Open Access Journals (Sweden)

Pía Villanueva

2009-09-01

Full Text Available OBJETIVO: determinar los patrones de articulación de fones consonánticos en sujetos de habla española chilena clases I, II y III esqueletal; comparar las diferencias fonéticas que existan entre clases esqueletales. MÉTODOS: se seleccionaron 54 individuos que cumplían con los criterios de inclusión determinados mediante un examen clínico intraoral y a través del análisis de Ricketts, y se conformaron los grupos de estudio de pacientes clases esqueletales I, II y III. Se les realizó un examen fonoarticulatorio estandarizado para determinar los fones modificados y el patrón articulatorio compensatorio realizado. RESULTADOS: se observaron cambios en el punto de articulación de fones consonánticos en las tres clases esqueletales, con diferencias significativas en los grupos de fones anteriores y medios entre pacientes clases I y II, sólo en el grupo de los fones anteriores entre pacientes I y III. Entre pacientes clases II y III no se observaron diferencias significativas. Se reportan modificaciones y compensaciones cualitativamente distintas entre las clases esqueletales. CONCLUSIONES: en relación a pacientes clase I, los pacientes clase II o III, presentan distinto grado de modificación en el punto de articulación de fones consonánticos. Las diferencias observadas se relacionan con los patrones esqueletales propios de cada clase.PURPOSE: to determine the consonant phonemes articulation patterns in Chilean skeletal class I, II and III Spanish speakers and compare their phonetic differences. METHODS: fifty-four skeletal class I, II and III subjects were selected, based on intraoral clinical examination and Ricketts cephalometric analysis, constituting the study groups. A standardized phonoarticulatory test was applied to each patient to determine the modified phonemes and their compensatory patterns. RESULTS: the findings indicate changes in articulation in all three groups. Significant differences were found in anterior and medium

Adsorption of Cr(VI and Speciation of Cr(VI and Cr(III in Aqueous Solutions Using Chemically Modified Chitosan

Directory of Open Access Journals (Sweden)

ChunYuan Tao

2012-05-01

Full Text Available A new type of grafting chitosan (CTS was synthesized using 2-hydroxyethyl- trimethyl ammonium chloride (HGCTS. The adsorption of Cr(VI on HGCTS was studied. The effect factors on adsorption and the adsorption mechanism were considered. The results indicated that the HGCTS could concentrate and separate Cr(VI at pH 4.0; the adsorption equilibrium time was 80 min; the maximum adsorption capacity was 205 mg/g. The adsorption isotherm and kinetics were investigated, equilibrium data agreed very well with the Langmuir model and the pseudo second-order model could describe the adsorption process better than the pseudo first-order model. A novel method for speciation of Cr(VI and Cr(III in environmental water samples has been developed using HGCTS as adsorbent and FAAS as determination means. The detection limit of this method was 20 ng/L, the relatively standard deviation was 1.2% and the recovery was 99%~105%.

Growth, morphology, and structural properties of group-III-nitride nanocolumns and nanodisks

International Nuclear Information System (INIS)

Calleja, E.; Ristic, J.; Fernandez-Garrido, S.; Sanchez-Garcia, M.A.; Grandal, J.; Cerutti, L.; Trampert, A.; Jahn, U.; Sanchez, G.; Griol, A.; Sanchez, B.

2007-01-01

The growth conditions to achieve group-III-nitride nanocolumns and nanocolumnar heterostructures by plasma-assisted molecular beam epitaxy are studied. The evolution of the nanocolumnar morphology with the growth conditions is determined for (Ga,Al)N and (In,Ga)N nanocolumns. The mechanisms behind the nanocolumnar growth under high N-rich conditions are clarified in the sense that no seeding or catalysts are required, as it is the case in the vapour-liquid-solid model that applies to most nanocolumns grown by metal organic chemical vapour deposition, either with group-III nitrides, II-VI or III-V compounds. Some examples of nanocolumnar heterostructures are given, like quantum disks and cylindrical nanocavities. Preliminary results on the growth of arrays of ordered GaN nanocolumns are reported. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Magnetic solid-phase extraction combined with graphite furnace atomic absorption spectrometry for speciation of Cr(III) and Cr(VI) in environmental waters.

Science.gov (United States)

Jiang, Hong-mei; Yang, Ting; Wang, Yan-hong; Lian, Hong-zhen; Hu, Xin

2013-11-15

A new approach of magnetic solid phase extraction (MSPE) coupled with graphite furnace atomic absorption spectrometry (GFAAS) has been developed for the speciation of Cr(III) and Cr(VI) using zincon-immobilized silica-coated magnetic Fe3O4 nanoparticles (Zincon-Si-MNPs) as the MSPE absorbent. Cr(III) was quantitatively reserved on the absorbent at pH 9.1 while total Cr was reserved at pH 6.5. The absorbed Cr species were eluted by using 2 mol/L HCl and detected by GFAAS. The concentration of Cr(VI) could be calculated by subtracting Cr(III) from total Cr. All the parameters affecting the separation and extraction efficiency of Cr species such as pH, extraction time, concentration and volume of eluent, sample volume and influence of co-existing ions were systematically examined and the optimized conditions were established accordingly. The detection limit (LOD) of the method was 0.016 and 0.011 ng mL(-1) for Cr(III) and Cr(VI), respectively, with the enrichment factor of 100 and 150. The precisions of this method (Relative standard deviation, RSD, n=7) for Cr(III) and Cr(VI) at 0.1 ng mL(-1) were 6.0% and 6.2%, respectively. In order to validate the proposed method, a certified reference material of environmental water was analyzed, and the result of Cr speciation was in good agreement with the certified value. This MSPE-GFAAS method has been successfully applied for the speciation of Cr(III) and Cr(VI) in lake and tap waters with the recoveries of 88-109% for the spiked samples. Moreover, the MSPE separation mechanism of Cr(III) and Cr(VI) based on their adsorption-desorption on Zincon-Si-MNPs has been explained through various spectroscopic characterization. © 2013 Elsevier B.V. All rights reserved.

Chemistry of the Colloidal Group II-VI Nanocrystal Synthesis

Energy Technology Data Exchange (ETDEWEB)

Liu, Haitao [Univ. of California, Berkeley, CA (United States)

2007-05-17

In the last two decades, the field of nanoscience andnanotechnology has witnessed tremendous advancement in the synthesis andapplication of group II-VI colloidal nanocrystals. The synthesis based onhigh temperature decomposition of organometallic precursors has becomeone of the most successful methods of making group II-VI colloidalnanocrystals. This methodis first demonstrated by Bawendi and coworkersin 1993 to prepare cadmium chalcogenide colloidal quantum dots and laterextended by others to prepare other group II-VI quantum dots as well asanisotropic shaped colloidal nanocrystals, such as nanorod and tetrapod.This dissertation focuses on the chemistry of this type of nanocrystalsynthesis. The synthesis of group II-VI nanocrystals was studied bycharacterizing the molecular structures of the precursors and productsand following their time evolution in the synthesis. Based on theseresults, a mechanism was proposed to account for the 2 reaction betweenthe precursors that presumably produces monomer for the growth ofnanocrystals. Theoretical study based on density functional theorycalculations revealed the detailed free energy landscape of the precursordecomposition and monomerformation pathway. Based on the proposedreaction mechanism, a new synthetic method was designed that uses wateras a novel reagent to control the diameter and the aspect ratio of CdSeand CdS nanorods.

Preconcentrative separation of chromium(III) species from chromium(VI) by cloud point extraction and determination by flame atomic absorption spectrometry

International Nuclear Information System (INIS)

Yildiz, Z.; Arslan, G.; Tor, A.

2011-01-01

We describe a high-throughput technique for the determination of chromium species in water samples by flame atomic absorption spectrometry (FAAS) after preconcentrative separation of Cr(III) species from Cr(VI) by cloud point extraction (CPE) using diethyldithiocarbamate (DDTC) as the chelating agent and the nonionic surfactant Triton X-100 as the extractant. The Cr(III)-DDTC complex is extracted if the temperature is higher than the CPE temperature of Triton X-100, while Cr(VI) remains in the aqueous phase. The Cr(III) in the surfactant phase was analyzed by FAAS, and the concentration of Cr(VI) was calculated by subtraction of Cr(III) from total chromium which was directly determined by FAAS. The effect of pH, concentration of chelating agent, surfactant, and equilibration temperature were investigated. The detection limit for Cr(III) was 0. 08 μg L -1 with an enrichment factor of 98, and the relative standard deviation was 1. 2% (n = 3, c = 100 μg L -1 ). A certified reference material and several water samples were analyzed with satisfactory results. (author)

Preparation and properties of N-Phenylbutyrohydroxamic acid and N-p-Chlorophenylbutyrohydroxamic acid and their uses as extracting agents for Chromium (VI), Molybdenum (VI), Titanium (IV) and Uranium (VI)

Energy Technology Data Exchange (ETDEWEB)

Abu Elnour, Sawsan Hassan [Department of Chemistry, Faculty of Science, University of Khartoum, Khartoum (Sudan)

1993-05-01

Two lignads, N-phenylbutyrohydroxamic acid (1), N-p-chlorophenylbutyryl chloride with {beta} phenyl-hydroylamine and N-p-chlorophenylhydroxylamine, respectively. The acids prepared were identified and characterised through their reactions with Vanadiun (V) and iron (III), their melting points, infra-red spectra and nitrogen content. The extractive properties of these acids towards the metals Cr (VI), Mo (VI), Ti (IV) and U (VI) were examined at different PH values. The percentage of maximum extraction with the two acids was found to be as follows : for Cr (VI) at PH 1, (100%) for both acids, Mo (VI) at PH 2 (33.34%) with acid (I) and (16.67%) with acid (II) and U (VI) at PH 6 (72%) with acid (I) and (76%) with acid (II). The metal: Ligand complexes ratios were determined by using the continuous variation method, the ratio of the two ligands with four metals was found to be 1:2. Finally the suitability of the two acids for spectrophotometric determination of four metals was examined.(Author) 90 refs. , 24 tabs. , 24 figs

Preparation and properties of N-Phenylbutyrohydroxamic acid and N-p-Chlorophenylbutyrohydroxamic acid and their uses as extracting agents for Chromium (VI), Molybdenum (VI), Titanium (IV) and Uranium (VI)

International Nuclear Information System (INIS)

Abu Elnour, Sawsan Hassan

1993-05-01

Two lignads, N-phenylbutyrohydroxamic acid (1), N-p-chlorophenylbutyryl chloride with β phenyl-hydroylamine and N-p-chlorophenylhydroxylamine, respectively. The acids prepared were identified and characterised through their reactions with Vanadiun (V) and iron (III), their melting points, infra-red spectra and nitrogen content. The extractive properties of these acids towards the metals Cr (VI), Mo (VI), Ti (IV) and U (VI) were examined at different PH values. The percentage of maximum extraction with the two acids was found to be as follows : for Cr (VI) at PH 1, (100%) for both acids, Mo (VI) at PH 2 (33.34%) with acid (I) and (16.67%) with acid (II) and U (VI) at PH 6 (72%) with acid (I) and (76%) with acid (II). The metal: Ligand complexes ratios were determined by using the continuous variation method, the ratio of the two ligands with four metals was found to be 1:2. Finally the suitability of the two acids for spectrophotometric determination of four metals was examined.(Author)

Sorption of environmentally relevant radionuclides (U(VI), Np(V)) and lanthanides (Nd(III)) on feldspar and mica

Energy Technology Data Exchange (ETDEWEB)

Richter, Constanze

2015-11-05

A safe storage of radioactive waste in repositories is an important task to protect humans and the environment from radio- and chemotoxicity. Long-term safety assessments predict the behavior of potential environmental contaminants like the actinides plutonium, uranium, or neptunium, in the near and far field of repositories. For such safety assessments, it is necessary to know the migration behavior of the contaminants in the environment, which is mainly dependent on the aquatic speciation, the solubility product of relevant solid phases, and the retardation due to sorption on surrounding minerals. Thus, an investigation of sorption processes of contaminants onto different minerals as well as the derivation of mineral specific surface complexation model (SCM) parameters is of great importance. Feldspar and mica are widely distributed in nature. They occur as components of granite, which is considered as a potential host rock for a repository in Germany, and in numerous other rocks, and thus also in the far field of nearly all repositories. However, their sorption behavior with actinides has only been scarcely investigated until now. In order to better characterize these systems and subsequently to integrate these minerals into the long-term safety assessments, this work focuses on the investigation of the sorption behavior of U(VI), Np(V), and Nd(III) as analogue for An(III) onto the minerals orthoclase and muscovite, representing feldspars and mica, respectively. All investigations were performed under conditions relevant to the far field of a repository. In addition to the extensive characterization of the minerals, batch sorption experiments, spectroscopic investigations, and surface complexation modeling were performed to elucidate the uptake and speciation of actinides on the mineral surfaces. In addition, the influence of microorganisms naturally occurring on the mineral surfaces and the effect of Ca{sup 2+} on U(VI) uptake on the minerals was studied. The

Sorption of environmentally relevant radionuclides (U(VI), Np(V)) and lanthanides (Nd(III)) on feldspar and mica

International Nuclear Information System (INIS)

Richter, Constanze

2015-01-01

A safe storage of radioactive waste in repositories is an important task to protect humans and the environment from radio- and chemotoxicity. Long-term safety assessments predict the behavior of potential environmental contaminants like the actinides plutonium, uranium, or neptunium, in the near and far field of repositories. For such safety assessments, it is necessary to know the migration behavior of the contaminants in the environment, which is mainly dependent on the aquatic speciation, the solubility product of relevant solid phases, and the retardation due to sorption on surrounding minerals. Thus, an investigation of sorption processes of contaminants onto different minerals as well as the derivation of mineral specific surface complexation model (SCM) parameters is of great importance. Feldspar and mica are widely distributed in nature. They occur as components of granite, which is considered as a potential host rock for a repository in Germany, and in numerous other rocks, and thus also in the far field of nearly all repositories. However, their sorption behavior with actinides has only been scarcely investigated until now. In order to better characterize these systems and subsequently to integrate these minerals into the long-term safety assessments, this work focuses on the investigation of the sorption behavior of U(VI), Np(V), and Nd(III) as analogue for An(III) onto the minerals orthoclase and muscovite, representing feldspars and mica, respectively. All investigations were performed under conditions relevant to the far field of a repository. In addition to the extensive characterization of the minerals, batch sorption experiments, spectroscopic investigations, and surface complexation modeling were performed to elucidate the uptake and speciation of actinides on the mineral surfaces. In addition, the influence of microorganisms naturally occurring on the mineral surfaces and the effect of Ca 2+ on U(VI) uptake on the minerals was studied. The

Kinetics of U(VI) reduction by a dissimilatory Fe(III)-reducing bacterium under non-growth conditions

International Nuclear Information System (INIS)

Truex, M.J.; Peyton, B.M.; Valentine, N.B.; Gorby, Y.A.

1997-01-01

Dissimilatory metal-reducing microorganisms may be useful in processes designed for selective removal of uranium from aqueous streams. These bacteria can use U(VI) as an electron acceptor and thereby reduce soluble U(VI) to insoluble U(IV). While significant research has been devoted to demonstrating and describing the mechanism of dissimilatory metal reduction, the reaction kinetics necessary to apply this for remediation processes have not been adequately defined. In this study, pure culture Shewanella alga strain BrY reduced U(VI) under non-growth conditions in the presence of excess lactate as the electron donor. Initial U(VI) concentrations ranged from 13 to 1,680microM. A maximum specific U(VI) reduction rate of 2.37 micromole-U(VI)/(mg-biomass h) and Monod half-saturation coefficient of 132 microM-U(VI) were calculated from measured U(VI) reduction rates. U(VI) reduction activity was sustained at 60% of this rate for at least 80 h. The initial presence of oxygen at a concentration equal to atmospheric saturation at 22 C delays but does not prevent U(VI) reduction. The rate of U(VI) reduction by BrY is comparable or better than rates reported for other metal reducing species. BrY reduces U(VI) at a rate that is 30% of its Fe(III) reduction rate

Chemistry of the Colloidal Group II-VI Nanocrystal Synthesis

International Nuclear Information System (INIS)

Liu, Haitao

2007-01-01

In the last two decades, the field of nanoscience and nanotechnology has witnessed tremendous advancement in the synthesis and application of group II-VI colloidal nanocrystals. The synthesis based on high temperature decomposition of organometallic precursors has become one of the most successful methods of making group II-VI colloidal nanocrystals. This method is first demonstrated by Bawendi and coworkers in 1993 to prepare cadmium chalcogenide colloidal quantum dots and later extended by others to prepare other group II-VI quantum dots as well as anisotropic shaped colloidal nanocrystals, such as nanorod and tetrapod. This dissertation focuses on the chemistry of this type of nanocrystal synthesis. The synthesis of group II-VI nanocrystals was studied by characterizing the molecular structures of the precursors and products and following their time evolution in the synthesis. Based on these results, a mechanism was proposed to account for the 2 reaction between the precursors that presumably produces monomer for the growth of nanocrystals. Theoretical study based on density functional theory calculations revealed the detailed free energy landscape of the precursor decomposition and monomer formation pathway. Based on the proposed reaction mechanism, a new synthetic method was designed that uses water as a novel reagent to control the diameter and the aspect ratio of CdSe and CdS nanorods

Chromium(III) and chromium(VI) release from leather during 8 months of simulated use.

Science.gov (United States)

Hedberg, Yolanda S; Lidén, Carola

2016-08-01

Chromium (Cr) release from Cr-tanned leather articles is a major cause of Cr contact dermatitis. It has been suggested that Cr(VI) release from leather is not necessarily an intrinsic property of the leather, but is strongly dependent on environmental conditions. To test this hypothesis for long-term (8 months) simulated use. The release of total Cr and Cr(VI) from Cr-tanned, unfinished leather was analysed in subsequent phosphate buffer (pH 8.0) immersions for a period of 7.5 months. The effect of combined ultraviolet treatment and alkaline solution (pH 12.1) was tested. Dry storage [20% relative humidity (RH)] was maintained between immersions. Atomic absorption spectroscopy, X-ray fluorescence and diphenylcarbazide tests were used. Cr(VI) release was dependent on previous dry storage or alkaline treatment, but not on duration or number of previous immersions. Cr(III) release decreased with time. Fifty-two percent of the total Cr released during the last immersion period was Cr(VI). Cr(VI) release exceeded 9 mg/kg in all immersion periods except in the first 10-day immersion (2.6 mg/kg). Cr(VI) release is primarily determined by environmental factors (RH prior to immersion, solution pH, and antioxidant content). The RH should be kept low prior to testing Cr(VI) release from leather. © 2016 The Authors. Contact Dermatitis published by John Wiley & Sons Ltd.

Liquid–liquid extraction of Pu(IV), U(VI) and Am(III) using malonamide in room temperature ionic liquid as diluent

International Nuclear Information System (INIS)

Rout, Alok; Venkatesan, K.A.; Srinivasan, T.G.; Vasudeva Rao, P.R.

2012-01-01

Highlights: ► Extraction of actinides using malonamide in room temperature ionic liquid. ► High distribution ratios of actinides in room temperature ionic liquid. ► Ion exchange mechanism. ► Stoichiometry of extraction. ► High separation factors of U(VI) and Pu(IV) over Am(III) and fission products. - Abstract: The extraction behavior of U(VI), Pu(IV) and Am(III) from nitric acid medium by a solution of N,N-dimethyl-N,N-dioctyl-2-(2-hexyloxyethyl)malonamide (DMDOHEMA) in the room temperature ionic liquid, 1–butyl–3–methylimidazolium bis(trifluoromethanesulfonyl)imide (C 4 mimNTf 2 ), was studied. The distribution ratio of these actinides in DMDOHEMA/C 4 mimNTf 2 was measured as a function of various parameters such as the concentration of nitric acid, DMDOHEMA, NTf 2 − , alkyl chain length of ionic liquid. The extraction of actinides in the absence of DMDOHEMA was insignificant and the distribution ratio achieved in conjunction with C 4 mimNTf 2 , was remarkable. The separation factor of U(VI) and Pu(IV) achieved with the use of DMDOHEMA, ionic liquid was compared with Am(III) and other fission products. The stoichiometry of the metal-solvate was determined to be 1:2 for U(VI) and Pu(IV) and 1:3 for Am(III).

Pulsed laser deposition of II-VI and III-V semiconductor materials

Energy Technology Data Exchange (ETDEWEB)

Mele, A.; Di Palma, T.M.; Flamini, C.; Giardini Guidoni, A. [Rome, Univ. `La Sapienza` (Italy). Dep. di Chimica

1998-12-01

Pulsed laser irradiation of a solid target involves electronic excitation and heating, followed by expansion from the target of the elliptical gas cloud (plume) which can be eventually condensed on a suitable substrate. Pulsed laser ablation has been found to be a valuable technique to prepare II-VI and III-V thin films of semiconductor materials. Pulsed laser ablation deposition is discussed in the light of the results of an investigation on CdS, CdSe, CdTe and CdSe/CdTe multilayers and AIN, GaN and InN together with Al-Ga-In-N heterostructures. [Italiano] L`irradiazione di un target solido, mediante un fascio laser impulsato, genera una serie di processi che possono essere schematizzati come segue: riscaldamento ed eccitazione elettronica del target, da cui consegue l`espulsione di materiale sotto forma di una nube gassosa di forma ellissoidale (plume), che espande e puo` essere fatta depositare su un opportuno substrato. L`ablazione lasersi e` rivelata una tecnica valida per preparare film sottili di composti di elementi del II-VI e del III-V gruppo della tavola periodica. La deposizione via ablazione laser viene discussa alla luce dei risultati ottenuti nella preparazione di film di CdS, CdSe, CdTe e di film multistrato di CdSe/CdTe, di film di AIN, GaN, InN e di eterostrutture di Al-Ga-In-N.

U(VI) and Eu(III) ion sorption in the interface solution-phosphate solids: Structural study and mechanisms

International Nuclear Information System (INIS)

Drot, Romuald

1998-01-01

As part of the storage of nuclear wastes in a deep underground disposal, radionuclides sorption on geological or engineered barriers is one of the most important factor which could enhance retardation. Thus, the knowledge of such mechanisms is needed. For this purpose, we chose to experimentally define sorption equilibria before performing simulation of retention data. Several phosphate compounds are potential candidates as engineered barrier additives. We considered Th 4 (PO 4 ) 4 P 2 O 7 , Zr 2 O(PO 4 ) 2 which allow to study the effect of PO 4 and P 2 O 7 groups separately. Eu(III) and U(IV) ions were used as structural probes in order to simulate actinides (III) and (VI) behavior. X-ray powder diffraction, IR spectroscopy and electron probe microanalysis were used to characterized the synthesized solids. Electrophoretic measurements showed an amphoteric behavior of surface sites. Moreover, laser spectro-fluorimetry experiments indicated that no diffusion phenomena of the sorbed ion inside the solid occurs. Thus, we considered that a surface complexation model should be applied. Laser spectro-fluorimetry and XPS allowed to determine the nature of surface sites. ZrP 2 O 7 presents only one single site (P 2 O 7 groups) whereas Th 4 (PO 4 ) 4 P 2 O 7 and Zr 2 O(PO 4 ) 2 admit two types of sites (PO 4 /P 2 O 7 and PO 4 /oxo groups, respectively). Sorbed species were identified using laser spectro-fluorimetry which indicate that, in KNO 3 0.5 M medium and for a known surface site, there are two surface complexes for U(VI) (sorption of UO 2+ 2 et de UO 2 NO + 3 species) and only one for Eu(III) (sorption of EuNO 2+ 3 ). They are linked to the substrate as bidentate inner sphere complexes (EXAFS study). Surface acidity constants were determined by simulation of potentiometric titration curves obtained for each solid suspension using FITEQL code (CCM). As sorption equilibria were defined, experimental retention data simulation was performed with respect to structural

Chemical Interaction between U(VI) and Eu(III) ions on a Silica Surface

International Nuclear Information System (INIS)

Park, K. K.; Cha, W. S.; Cho, H. R.; Im, H. J.; Jung, E. C.

2010-01-01

Understanding the chemical behavior of actinide in groundwater flow is important for assessing the possibility of its migration with water flow in the radioactive waste disposal site. Precipitation/ dissolution in groundwater and adsorption/desorption onto a geological solid surface would determine its migration. The sorption in a geochemical system was expected to be a reaction on a naturally equilibrated surface. However, the construction of a waste disposal facility could disturb this equilibrium state, induce a new reaction environment and affect a nanoscopic surface reaction of actinide. Uranium is ubiquitous in the natural environment and a representative element in a nuclear fuel cycle and in a high level radioactive waste. In oxic environments, it is typically present as uranyl oxocation (UO 2 2+ ), which is easily adsorbed and thereby removed from a solution in the near neutral pH range. This adsorption would form a new surface condition to give an unexpected adsorption behavior for other actinide ions. Eu(III) frequently is used as a chemical analogue of Am(III) and Cm(III) in migration chemistry. The adsorption phenomena has been interpreted with the help of a SCM(surface complexation model). Some spectroscopic techniques such as EPR (Electron Paramagnetic Resonance), IR (InfraRed), EXAFS (Extended X-ray Absorption Fine Structure) and TRLFS (Time Resolved Laser Fluorescence Spectroscopy) have been used for the identification of a modeled adsorbing species. In the case of fluorescence elements, TRLFS has advantages over other techniques for its high sensitivity being proportional to laser source intensity and good selectivity depending on specific transition and lifetime. This technique can be applied to a species on a solid surface not absorbing light such as silica. U(VI) and Eu(III) have fluorescente properties reflecting their coordination structure. In this study, the interaction between U(VI) and Eu(III) on a silica surface was studied by a

Cr(VI) and Cr(III) removal from aqueous solution by raw and modified lignocellulosic materials: a review.

Science.gov (United States)

Miretzky, P; Cirelli, A Fernandez

2010-08-15

In aqueous systems, chromium usually exists in both trivalent and hexavalent oxidation states, being Cr(VI) of particular importance and concern due to its great toxicity. Industrial sources of Cr(VI) are leather tanning, mining of chrome ore, production of steel and alloys, etc. The most common conventional method for Cr(VI) removal is reduction to Cr(III) at pH 2.0 and precipitation of Cr (OH)(3) with lime at pH 9-10. The disadvantage of precipitation is the disposal of the solid waste. Adsorption of Cr by different low cost materials seems to be a suitable choice for wastewater treatment. Many by-products of agriculture have proved to be suitable low cost adsorbents for Cr(VI) and Cr(III) removal from water. Lignocellulosic residues, which include both wood residues and agricultural residues, have adsorption capacity comparable to other natural sorbents, but they have the advantage of very low or no cost, great availability and simple operational process. This study is a review of the recent literature on the use of natural and modified lignocellulosic residues for Cr adsorption. The Cr maximum adsorption capacity and the adsorption mechanism under different experimental conditions are reported when possibly. Copyright 2010 Elsevier B.V. All rights reserved.

Separation of Cr(III) from Cr(VI) by Triton X-100 cerium(IV) phosphate as a surface active ion exchanger

International Nuclear Information System (INIS)

El-Azony, K.M.; Ismail Aydia, M.; El-Mohty, A.A.

2011-01-01

Triton X-100 cerium(IV) phosphate (TX-100CeP) was synthesized and characterized by using IR, X-ray, TGA/DT and the elemental analysis. The chemical stability of TX-100CeP versus the different concentrations of HCl acid was studied before and after its exposure to the radiation dose (30 K Gray). The effect of HCl concentration on separation of Cr(III) from Cr(VI) by using TX-100CeP as surface active ion exchanger was also studied. A novel method was achieved for the quantifying of Cr(III) and Cr(VI) ions by using the high-performance liquid chromatography (HPLC) at wavelength 650 nm, a stationary phase consists of reversed phase column (Nucleosil phenyl column; 250 x 4.6 mm, 5 μm), and a mobile phase consists of 0.001 M di-(2-ethylhexyl) phosphoric acid (DEHPA) in methanol:water (70:30 v/v). The retention times were 7.0 and 8.5 min, for the Cr(III) and Cr(VI), respectively. The exchange capacity of Cr(III) was quantified (2.1 meq/g) onto the TX-100CeP. (author)

A{sup I}B{sup III}C{sup VI}{sub 2} (A = Cu, Ag; B = Ga, In; C = S, Se, Te) based photonic crystal superlattices: Optical properties

Energy Technology Data Exchange (ETDEWEB)

Simsek, Sevket [Faculty of Engineering, Department of Material Science and Engineering, Hakkari University, 3000, Hakkari (Turkey); Palaz, Selami [Faculty of Science and Letters, Department of Physics, Harran University, 63000, Sanliurfa (Turkey); Akhundov, Chingiz [International Scientific Center, Baku State University, Baku (Azerbaijan); Mamedov, Amirullah M. [International Scientific Center, Baku State University, Baku (Azerbaijan); Nanotechnology Research Center, Bilkent University, 06800, Ankara (Turkey); Ozbay, Ekmel [Nanotechnology Research Center, Bilkent University, 06800, Ankara (Turkey)

2017-06-15

In this study, we present an investigation of the optical properties and band structures for the photonic structures based on A{sup I}B{sup III}C{sup VI}{sub 2} with a Fibonacci sequence that can act as a multi-wavelength birefringent filter. The filtering wavelengths are analyzed by the indices concerning the quasi-periodicity of a Fibonacci sequence and the average lattice parameter. The transmittances of filtering wavelengths can be tuned by varying structure parameters such as the lengths of poled domains, filling factor, and dispersion relation. In our simulation, we employed the finite-difference time domain (FDTD) technique, which implies a solution from Maxwell equation. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Dissolved nutrients and atrazine removal by column-scale monophasic and biphasic rain garden model systems.

Science.gov (United States)

Yang, Hanbae; McCoy, Edward L; Grewal, Parwinder S; Dick, Warren A

2010-08-01

Rain gardens are bioretention systems that have the potential to reduce peak runoff flow and improve water quality in a natural and aesthetically pleasing manner. We compared hydraulic performance and removal efficiencies of nutrients and atrazine in a monophasic rain garden design versus a biphasic design at a column-scale using simulated runoff. The biphasic rain garden was designed to increase retention time and removal efficiency of runoff pollutants by creating a sequence of water saturated to unsaturated conditions. We also evaluated the effect of C substrate availability on pollutant removal efficiency in the biphasic rain garden. Five simulated runoff events with various concentrations of runoff pollutants (i.e. nitrate, phosphate, and atrazine) were applied to the monophasic and biphasic rain gardens once every 5d. Hydraulic performance was consistent over the five simulated runoff events. Peak flow was reduced by approximately 56% for the monophasic design and 80% for the biphasic design. Both rain garden systems showed excellent removal efficiency of phosphate (89-100%) and atrazine (84-100%). However, significantly (prain garden (29-39%). Addition of C substrate in the form of glucose increased removal efficiency of nitrate significantly (prain gardens. (c) 2010 Elsevier Ltd. All rights reserved.

Study of the Thermodynamics of Chromium(III) and Chromium(VI) Binding to Fe3O4 and MnFe2O4 nanoparticles

Science.gov (United States)

Luther, Steven; Brogfeld, Nathan; Kim, Jisoo; Parsons, J.G.

2013-01-01

Removal of chromium(III) or (VI) from aqueous solution was achieved using Fe3O4, and MnFe2O4 nanomaterials. The nanomaterials were synthesized using a precipitation method and characterized using XRD. The size of the nanomaterials was determined to be 22.4 ± 0.9 nm (Fe3O4) and 15.5 ± 0.5 nm (MnFe2O4). The optimal binding pH for chromium(III) and chromium(VI) were pH 6 and pH 3. Isotherm studies were performed, under light and dark conditions, to determine the capacity of the nanomaterials. The capacities for the light studies with MnFe2O4 and Fe3O4 were determined to be 7.189 and 10.63 mg/g, respectively, for chromium(III). The capacities for the light studies with MnFe2O4 and Fe3O4 were 3.21 and 3.46 mg/g, respectively, for chromium(VI). Under dark reaction conditions the binding of chromium(III) to the MnFe2O4 and Fe3O4 nanomaterials were 5.74 and 15.9 mg/g, respectively. The binding capacity for the binding of chromium(VI) to MnFe2O4 and Fe3O4 under dark reaction conditions were 3.87 and 8.54 mg/g, respectively. The thermodynamics for the reactions showed negative ΔG values, and positive ΔH values. The ΔS values were positive for the binding of chromium(III) and for chromium(VI) binding under dark reaction conditions. The ΔS values for chromium(VI) binding under the light reaction conditions were determined to be negative. PMID:23558081

Collagen Type III and VI Turnover in Response to Long-Term Immobilization.

Directory of Open Access Journals (Sweden)

Shu Sun

Full Text Available Muscle mass and function are perturbed by immobilization and remobilization. When muscle mass changes, the quality and quantity of the extracellular matrix protein, particularly the collagens, change with it. In this study, we investigated the temporal profile of three peptide biomarkers derived from turnover of collagen type III and type VI in a long-term immobilization and remobilization study. We also compared individual biomarker levels with Lean body Mass (LBM and changes therein, hypothesizing that these biomarkers would be biomarkers of the remodeling processes associated with immobilization and/or remobilization.In the Berlin bed rest study, 20 young men were recruited and randomly assigned to 8-week's strict bed rest with or without resistive vibration exercise countermeasure. We measured three neo-epitope ELISA kits in the serum samples of this study: Pro-C3, measured the synthesis of collagen type III; Pro-C6, measured the synthesis of collagen type VI; and C6M measured the degradation of collagen type VI induced by MMP-2 and MMP-9 cleavage.Pro-C3 and Pro-C6 biomarkers are up-regulated with both immobilization and remobilization, whereas C6M is hardly affected at all. We found that Pro-C3 and C6M levels are related to LBM at baseline and that high levels of Pro-C6 are associated with smaller changes in muscle mass during both immobilization and remobilization.The Pro-C3 and-C6 biomarkers change likely reflect remodeling changes in response to unloading or reloading, whereas C6M does not appear to respond to unloading. Pro-C3 and C6M levels correlate with LBM at baseline, while Pro-C6 is related to the anabolic and catabolic responses to unloading and reloading.

Determination of Cr(VI) and Cr(III) in urine and dextrose by inductively coupled plasma emission spectroscopy

Science.gov (United States)

Mianzhi, Zhuang; Barnes, Ramon M.

The determination of Cr(VI) and Cr(III) in human urine and in commercial dextrose solution is performed by induclively coupled plasma-atomic emission spectroscopy after selective preconcentration of the chromium species at different pH values by poly(dithiocarbamate) and poly(acrylamidoxime) chelating resins. The chelating properties of these resins with chromium, including the kinetics of uptake and removal of Cr(III), and the influence of matrix concentrations were evaluated. Chromium in human urine was found to exist exclusively as Cr(III).

Room temperature ionic liquids enhanced the speciation of Cr(VI) and Cr(III) by hollow fiber liquid phase microextraction combined with flame atomic absorption spectrometry

Energy Technology Data Exchange (ETDEWEB)

Zeng, Chujie, E-mail: cjzeng@126.com [Department of Chemistry and Material, Yulin Normal College, Yulin, Guangxi 537000 (China); Lin, Yao; Zhou, Neng; Zheng, Jiaoting; Zhang, Wei [Department of Chemistry and Material, Yulin Normal College, Yulin, Guangxi 537000 (China)

2012-10-30

Highlights: Black-Right-Pointing-Pointer First reported enhancement effect of RTILs in HF-LPME for the speciation of chromium. Black-Right-Pointing-Pointer The addition of RTILs led to 3.5 times improvement of the sensitivity of Cr(VI). Black-Right-Pointing-Pointer The proposed method is a simplicity, sensitivity, low cost, green method. - Abstract: A new method for the speciation of Cr(VI) and Cr(III) based on enhancement effect of room temperature ionic liquids (RTILs) for hollow fiber liquid phase microextraction (HF-LPME) combined with flame atomic absorption spectrometry (FAAS) was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagents and chelating reagent, respectively. The addition of room temperature ionic liquids led to 3.5 times improvement in the determination of Cr(VI). In this method, Cr(VI) reacts with DDTC yielding a hydrophobic complex, which is subsequently extracted into the lumen of hollow fiber, whereas Cr(III) is remained in aqueous solutions. The extraction organic phase was injected into FAAS for the determination of Cr(VI). Total Cr concentration was determined after oxidizing Cr(III) to Cr(VI) in the presence of KMnO{sub 4} and using the extraction procedure mentioned above. Cr(III) was calculated by subtracting of Cr(VI) from the total Cr. Under optimized conditions, a detection limit of 0.7 ng mL{sup -1} and an enrichment factor of 175 were achieved. The relative standard deviation (RSD) was 4.9% for Cr(VI) (40 ng mL{sup -1}, n = 5). The proposed method was successfully applied to the speciation of chromium in natural water samples with satisfactory results.

Room temperature ionic liquids enhanced the speciation of Cr(VI) and Cr(III) by hollow fiber liquid phase microextraction combined with flame atomic absorption spectrometry

International Nuclear Information System (INIS)

Zeng, Chujie; Lin, Yao; Zhou, Neng; Zheng, Jiaoting; Zhang, Wei

2012-01-01

Highlights: ► First reported enhancement effect of RTILs in HF-LPME for the speciation of chromium. ► The addition of RTILs led to 3.5 times improvement of the sensitivity of Cr(VI). ► The proposed method is a simplicity, sensitivity, low cost, green method. - Abstract: A new method for the speciation of Cr(VI) and Cr(III) based on enhancement effect of room temperature ionic liquids (RTILs) for hollow fiber liquid phase microextraction (HF-LPME) combined with flame atomic absorption spectrometry (FAAS) was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagents and chelating reagent, respectively. The addition of room temperature ionic liquids led to 3.5 times improvement in the determination of Cr(VI). In this method, Cr(VI) reacts with DDTC yielding a hydrophobic complex, which is subsequently extracted into the lumen of hollow fiber, whereas Cr(III) is remained in aqueous solutions. The extraction organic phase was injected into FAAS for the determination of Cr(VI). Total Cr concentration was determined after oxidizing Cr(III) to Cr(VI) in the presence of KMnO 4 and using the extraction procedure mentioned above. Cr(III) was calculated by subtracting of Cr(VI) from the total Cr. Under optimized conditions, a detection limit of 0.7 ng mL −1 and an enrichment factor of 175 were achieved. The relative standard deviation (RSD) was 4.9% for Cr(VI) (40 ng mL −1 , n = 5). The proposed method was successfully applied to the speciation of chromium in natural water samples with satisfactory results.

Modeling of kinetics of Cr(VI) sorption onto grape stalk waste in a stirred batch reactor

International Nuclear Information System (INIS)

Escudero, Carlos; Fiol, Nuria; Poch, Jordi; Villaescusa, Isabel

2009-01-01

Recently, Cr(VI) removal by grape stalks has been postulated to follow two mechanisms, adsorption and reduction to trivalent chromium. Nevertheless, the rate at which both processes take place and the possible simultaneity of both processes has not been investigated. In this work, kinetics of Cr(VI) sorption onto grape stalk waste has been studied. Experiments were carried out at different temperatures but at a constant pH (3 ± 0.1) in a stirred batch reactor. Results showed that three steps take place in the process of Cr(VI) sorption onto grape stalk waste: Cr(VI) sorption, Cr(VI) reduction to Cr(III) and the adsorption of the formed Cr(III). Taking into account the evidences above mentioned, a model has been developed to predict Cr(VI) sorption on grape stalks on the basis of (i) irreversible reduction of Cr(VI) to Cr(III) reaction, whose reaction rate is assumed to be proportional to the Cr(VI) concentration in solution and (ii) adsorption and desorption of Cr(VI) and formed Cr(III) assuming that all the processes follow Langmuir type kinetics. The proposed model fits successfully the kinetic data obtained at different temperatures and describes the kinetics profile of total, hexavalent and trivalent chromium. The proposed model would be helpful for researchers in the field of Cr(VI) biosorption to design and predict the performance of sorption processes.

U(VI) and Eu(III) ion sorption in the interface solution-phosphate solids: Structural study and mechanisms; Sorption des ions U(VI) et Eu(III) a l`interface solution - solides phosphates: Etude structurale et mechanismes

Energy Technology Data Exchange (ETDEWEB)

Drot, Romuald [Inst. de Physique Nucleaire, Paris-11 Univ., 91 - Orsay (France)

1998-09-18

As part of the storage of nuclear wastes in a deep underground disposal, radionuclides sorption on geological or engineered barriers is one of the most important factor which could enhance retardation. Thus, the knowledge of such mechanisms is needed. For this purpose, we chose to experimentally define sorption equilibria before performing simulation of retention data. Several phosphate compounds are potential candidates as engineered barrier additives. We considered Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}, Zr{sub 2}O(PO{sub 4}){sub 2} which allow to study the effect of PO{sub 4} and P{sub 2}O{sub 7} groups separately. Eu(III) and U(IV) ions were used as structural probes in order to simulate actinides (III) and (VI) behavior. X-ray powder diffraction, IR spectroscopy and electron probe microanalysis were used to characterized the synthesized solids. Electrophoretic measurements showed an amphoteric behavior of surface sites. Moreover, laser spectro-fluorimetry experiments indicated that no diffusion phenomena of the sorbed ion inside the solid occurs. Thus, we considered that a surface complexation model should be applied. Laser spectro-fluorimetry and XPS allowed to determine the nature of surface sites. ZrP{sub 2}O{sub 7} presents only one single site (P{sub 2}O{sub 7} groups) whereas Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7} and Zr{sub 2}O(PO{sub 4}){sub 2} admit two types of sites (PO{sub 4}/P{sub 2}O{sub 7} and PO{sub 4}/oxo groups, respectively). Sorbed species were identified using laser spectro-fluorimetry which indicate that, in KNO{sub 3} 0.5 M medium and for a known surface site, there are two surface complexes for U(VI) (sorption of UO{sup 2+}{sub 2} et de UO{sub 2}NO{sup +}{sub 3} species) and only one for Eu(III) (sorption of EuNO{sup 2+}{sub 3}). They are linked to the substrate as bidentate inner sphere complexes (EXAFS study). Surface acidity constants were determined by simulation of potentiometric titration curves obtained for each solid

Site-specific functionalization for chemical speciation of Cr(III) and Cr(VI) using polyaniline impregnated nanocellulose composite: equilibrium, kinetic, and thermodynamic modeling

Science.gov (United States)

Jain, Priyanka; Varshney, Shilpa; Srivastava, Shalini

2017-07-01

Site-specific functionalizations are the emergent attention for the enhancement of sorption latent of heavy metals. Limited chemistry has been applied for the fabrication of diafunctionalized materials having potential to tether both environmentally stable oxidation states of chromium (Cr(III) and Cr(VI). Polyaniline impregnated nanocellulose composite (PANI-NCC) has been fabricated using click chemistry and explored for the removal of Cr(III) and Cr(VI) from hydrological environment. The structure, stability, morphology, particle size, surface area, hydrophilicity, and porosity of fabricated PANI-NCC were characterized comprehensively using analytical techniques and mathematical tools. The maximum sorption performance of PANI-NCC was procured for (Cr(III): 47.06 mg g-1; 94.12 %) and (Cr(VI): 48.92 mg g-1; 97.84 %) by equilibrating 0.5 g sorbent dose with 1000 mL of 25 mg L-1 chromium conc. at pH 6.5 and 2.5 for Cr(III) and Cr(VI), respectively. The sorption data showed a best fit to the Langmuir isotherm and pseudo-second-order kinetic model. The negative value of Δ G° (-8.59 and -11.16 kJ mol-1) and Δ H° (66.46 × 10-1 and 17.84 × 10-1 kJ mol-1), and positive value of Δ S° (26.66 and 31.46 J mol-1K-1) for Cr(III) and Cr(VI), respectively, reflect the spontaneous, feasibility, and exothermic nature of the sorption process. The application of fabricated PANI-NCC for removing both the forms of chromium in the presence of other heavy metals was also tested at laboratory and industrial waste water regime. These findings open up new avenues in the row of high performance, scalable, and economic nanobiomaterial for the remediation of both forms of chromium from water streams.

New approach in modeling Cr(VI) sorption onto biomass from metal binary mixtures solutions

Energy Technology Data Exchange (ETDEWEB)

Liu, Chang [College of Environmental Science and Engineering, Anhui Normal University, South Jiuhua Road, 189, 241002 Wuhu (China); Chemical Engineering Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain); Fiol, Núria [Chemical Engineering Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain); Villaescusa, Isabel, E-mail: Isabel.Villaescusa@udg.edu [Chemical Engineering Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain); Poch, Jordi [Applied Mathematics Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain)

2016-01-15

In the last decades Cr(VI) sorption equilibrium and kinetic studies have been carried out using several types of biomasses. However there are few researchers that consider all the simultaneous processes that take place during Cr(VI) sorption (i.e., sorption/reduction of Cr(VI) and simultaneous formation and binding of reduced Cr(III)) when formulating a model that describes the overall sorption process. On the other hand Cr(VI) scarcely exists alone in wastewaters, it is usually found in mixtures with divalent metals. Therefore, the simultaneous removal of Cr(VI) and divalent metals in binary mixtures and the interactive mechanism governing Cr(VI) elimination have gained more and more attention. In the present work, kinetics of Cr(VI) sorption onto exhausted coffee from Cr(VI)–Cu(II) binary mixtures has been studied in a stirred batch reactor. A model including Cr(VI) sorption and reduction, Cr(III) sorption and the effect of the presence of Cu(II) in these processes has been developed and validated. This study constitutes an important advance in modeling Cr(VI) sorption kinetics especially when chromium sorption is in part based on the sorbent capacity of reducing hexavalent chromium and a metal cation is present in the binary mixture. - Highlights: • A kinetic model including Cr(VI) reduction, Cr(VI) and Cr(III) sorption/desorption • Synergistic effect of Cu(II) on Cr(VI) elimination included in the model • Model validation by checking it against independent sets of data.

New approach in modeling Cr(VI) sorption onto biomass from metal binary mixtures solutions

International Nuclear Information System (INIS)

Liu, Chang; Fiol, Núria; Villaescusa, Isabel; Poch, Jordi

2016-01-01

In the last decades Cr(VI) sorption equilibrium and kinetic studies have been carried out using several types of biomasses. However there are few researchers that consider all the simultaneous processes that take place during Cr(VI) sorption (i.e., sorption/reduction of Cr(VI) and simultaneous formation and binding of reduced Cr(III)) when formulating a model that describes the overall sorption process. On the other hand Cr(VI) scarcely exists alone in wastewaters, it is usually found in mixtures with divalent metals. Therefore, the simultaneous removal of Cr(VI) and divalent metals in binary mixtures and the interactive mechanism governing Cr(VI) elimination have gained more and more attention. In the present work, kinetics of Cr(VI) sorption onto exhausted coffee from Cr(VI)–Cu(II) binary mixtures has been studied in a stirred batch reactor. A model including Cr(VI) sorption and reduction, Cr(III) sorption and the effect of the presence of Cu(II) in these processes has been developed and validated. This study constitutes an important advance in modeling Cr(VI) sorption kinetics especially when chromium sorption is in part based on the sorbent capacity of reducing hexavalent chromium and a metal cation is present in the binary mixture. - Highlights: • A kinetic model including Cr(VI) reduction, Cr(VI) and Cr(III) sorption/desorption • Synergistic effect of Cu(II) on Cr(VI) elimination included in the model • Model validation by checking it against independent sets of data

Hexagonal perovskites with cationic vacancies. 19. The rhombohedral 12 L stacking polytypes Ba/sub 3/LaBsup(III) (W/sub 2/sup(VI)vacantO/sub 12/)

Energy Technology Data Exchange (ETDEWEB)

Rother, H J; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1980-06-01

Hexagonal perovskites are described for the new type Ba/sub 3/LaBsup(III)(W/sub 2/sup(VI)vacantO/sub 12/) with Bsup(III) = Sc, In, Lu, Yb. According to the intensity calculations for Ba/sub 3/LaIn(W/sub 2/vacantO/sub 12/) they crystallize in a rhombohedral 12 L structure with the sequence (3)(1) respectively (hhcc)/sub 3/; space group R3m. The refined, intensity related R' value is 6.7%.

Oxidation of Cr(III)-Fe(III) Mixed-phase Hydroxides by Chlorine: Implications on the Control of Hexavalent Chromium in Drinking Water.

Science.gov (United States)

Chebeir, Michelle; Liu, Haizhou

2018-05-17

The occurrence of chromium (Cr) as an inorganic contaminant in drinking water is widely reported. One source of Cr is its accumulation in iron-containing corrosion scales of drinking water distribution systems as Cr(III)-Fe(III) hydroxide, i.e., FexCr(1-x)(OH)3(s), where x represents the Fe(III) molar content and typically varies between 0.25 and 0.75. This study investigated the kinetics of inadvertent hexavalent chromium Cr(VI) formation via the oxidation of FexCr(1-x)(OH)3(s) by chlorine as a residual disinfectant in drinking water, and examined the impacts of Fe(III) content and drinking water chemical parameters including pH, bromide and bicarbonate on the rate of Cr(VI) formation. Data showed that an increase in Fe(III) molar content resulted in a significant decrease in the stoichiometric Cr(VI) yield and the rate of Cr(VI) formation, mainly due to chlorine decay induced by Fe(III) surface sites. An increase in bicarbonate enhanced the rate of Cr(VI) formation, likely due to the formation of Fe(III)-carbonato surface complexes that slowed down the scavenging reaction with chlorine. The presence of bromide significantly accelerated the oxidation of FexCr(1-x)(OH)3(s) by chlorine, resulting from the catalytic effect of bromide acting as an electron shuttle. A higher solution pH between 6 and 8.5 slowed down the oxidation of Cr(III) by chlorine. These findings suggested that the oxidative conversion of chromium-containing iron corrosion products in drinking water distribution systems can lead to the occurrence of Cr(VI) at the tap, and the abundance of iron, and a careful control of pH, bicarbonate and bromide levels can assist the control of Cr(VI) formation.

Computed oscillator strengths and energy levels for Fe III, Fe IV, Fe V, and Fe VI with calculated wavelengths and wavelengths derived from established data

International Nuclear Information System (INIS)

Fawcett, B.C.

1989-01-01

Calculated weighted oscillator strengths are tabulated for spectral lines of Fe III, Fe IV, Fe V, and Fe VI. The lines belong to transition arrays 3d 6 -3d 5 4p and 3d 5 4s-3d 5 4p in Fe III, 3d 5 -3d 4 4p and 3d 4 4s-3d 4 4p in Fe IV, 3d 4 -3d 3 4p and 3d 3 4s-3d 3 4p in Fe V, and 3d 3 -3d 2 4p and 3d 2 4s-3d 2 4p in Fe VI. For the calculations, Slater parameters are optimized on the basis of minimizing the discrepancies between observed and computed wavelengths. Configuration interaction was included among the 3d n , 3d n-1 4s, 3d n-2 4s 2 , 3d n-1 4d, and 3d n-1 5s even configurations and among the 3d n-1 4p, 3d n-2 4s4p, and 3d n-1 5p odd configurations, with 3p 5 3d n+1 added for Fe VI. Calculated wavelengths are compared with observational data, and the compositions of energy levels are listed. This completes a series of similar computations for these complex configurations covering Fe I to Fe VI

SAM-VI RNAs selectively bind S-adenosylmethionine and exhibit similarities to SAM-III riboswitches.

Science.gov (United States)

Mirihana Arachchilage, Gayan; Sherlock, Madeline E; Weinberg, Zasha; Breaker, Ronald R

2018-03-04

Five distinct riboswitch classes that regulate gene expression in response to the cofactor S-adenosylmethionine (SAM) or its metabolic breakdown product S-adenosylhomocysteine (SAH) have been reported previously. Collectively, these SAM- or SAH-sensing RNAs constitute the most abundant collection of riboswitches, and are found in nearly every major bacterial lineage. Here, we report a potential sixth member of this pervasive riboswitch family, called SAM-VI, which is predominantly found in Bifidobacterium species. SAM-VI aptamers selectively bind the cofactor SAM and strongly discriminate against SAH. The consensus sequence and structural model for SAM-VI share some features with the consensus model for the SAM-III riboswitch class, whose members are mainly found in lactic acid bacteria. However, there are sufficient differences between the two classes such that current bioinformatics methods separately cluster representatives of the two motifs. These findings highlight the abundance of RNA structures that can form to selectively recognize SAM, and showcase the ability of RNA to utilize diverse strategies to perform similar biological functions.

Selective and sensitive speciation analysis of Cr(VI) and Cr(III), at sub-μgL-1 levels in water samples by electrothermal atomic absorption spectrometry after electromembrane extraction.

Science.gov (United States)

Tahmasebi, Zeinab; Davarani, Saied Saeed Hosseiny

2016-12-01

In this work, electromembrane extraction in combination with electrothermal atomic absorption spectrometry (ET-AAS) was investigated for speciation, preconcentration and quantification of Cr(VI) and Cr(III) in water samples through the selective complexation of Cr(VI) with 1,5-diphenylcarbazide (DPC) as a complexing agent. DPC reduces Cr(VI) to Cr(III) ions and then Cr(III) species are extracted based on electrokinetic migration of their cationic complex (Cr(III)-DPC) toward the negative electrode placed in the hollow fiber. Also, once oxidized to Cr(VI), Cr(III) ions in initial sample were determined by this procedure. The influence of extraction parameters such as pH, type of organic solvent, chelating agent concentration, stirring rate, extraction time and applied voltage were evaluated following a one-at-a-time optimization approach. Under optimized conditions, the extracted analyte was quantified by ETAAS, with an acceptable linearity in the range of 0.05-5ngmL -1 (R 2 value=0.996), and a repeatability (%RSD) between 3.7% and 12.2% (n=4) for 5.0 and 1.0ngmL -1 of Cr(VI), respectively. Also, we obtained an enrichment factor of 110 that corresponded to the recovery of 66%. The detection limit (S/N ratio of 3:1) was 0.02ngmL -1 . Finally, this new method was successfully employed to determine Cr(III) and Cr(VI) species in real water samples. Copyright © 2016. Published by Elsevier B.V.

PIG-B: a homemade monophasic cocktail for the extraction of RNA.

Science.gov (United States)

Weber, K; Bolander, M E; Sarkar, G

1998-02-01

An inexpensive monophasic reagent has been developed for the extraction of total RNA from cells or tissues. The main ingredients of the reagent are Phenol, Isoamyl alcohol, Guanidinium isothiocyanate, and Beta-mercaptoethanol (PIG-B). The quality and yield of RNA obtained by this reagent is at par with that obtained by TRIzol, an expensive but widely used monophasic reagent available commercially. The complete composition and method of preparation of PIG-B is provided to aid preparation of the reagent in the laboratory.

Kinetics and mechanism of the conversion of a coordinated thiol to a coordinated disulfide by the one-equivalent oxidants neptunium(VI) and cobalt(III) in aqueous perchloric acid

International Nuclear Information System (INIS)

Woods, M.; Karbwang, J.; Sullivan, J.C.; Deutsch, E.

1976-01-01

Reaction of excess (2-mercaptoethylamine-N,S)bis(ethylenediamine)cobalt(III), I, with the 1-equiv oxidant Np(VI) (or Co 3+ (aq)) in aqueous perchloric acid media is shown to lead to (2-aminoethyl-N 2-ammonioethyl disulfide-S 1 ) bis(ethylenediamine)cobalt(III), II, according to the stoichiometry 5H + + 2I + Np(VI) → II + Co 2+ (aq) + Np(V) + 2enH 2 2+ . This reaction follows the rate law -d[I]/dt = k'' [I] [oxidant]. For Np(VI) as oxidant k'' is independent of [H + ]; at 25 0 C, μ = 1.00 M (LiClO 4 ), k'' = k 0 = 2842 +- 15 M -1 s -1 , ΔH 0 * = 7.57 +- 0.08 kcal/mol, and ΔS 0 * = -17.4 +- 0.3 eu. For Co 3+ (aq) as oxidant, k'' = k 0 + k/sub -1/[H + ] -1 where the inverse acid path is taken to reflect oxidation by CoOH 2+ (aq); at 25 0 C, μ = 1.00 M (LiClO 4 ), k 0 = 933 +- 32 M -1 s -1 , k/sub -1/ = 1152 +- 22 s -1 , ΔH 0 * = 12.5 +- 0.7 kcal/mol, ΔH*/sub -1/ = 18.0 +- 0.4 kcal/mol, ΔS 0 *= -3.1 +- 2.4 eu, and ΔS*/sub -1/ = 15.8 +- 1.2 eu. It is proposed that the conversion of I to II proceeds by initial 1-equiv oxidation of the coordinated thiol, reaction of the resultant coordinated thiol radical (RS.) with additional I to form a relatively stable radical ion dimer (RSSR. - ), and then internal electron transfer within the dimer to yield Co 2+ (aq) and II which contains a coordinated disulfide. The possible generality of this mechanism and its relevance to biological metal-thiol-disulfide interactions are noted

LABORATORY STUDY FOR THE REDUCTION OF CHROME (VI) TO CHROME (III) USING SODIUM METABISULFITE UNDER ACIDIC CONDITIONS

International Nuclear Information System (INIS)

DUNCAM JB; GUTHRIE MD; LUECK KJ; AVILA M

2007-01-01

This report describes the results from RPP-PLAN-32738, 'Test Plan for the Effluent Treatment Facility to Reduce Chrome(VI) to Chrome(I1I) in the Secondary Waste Stream', using sodium metabisulfite. Appendix A presents the report as submitted by the Center for Laboratory Sciences (CLS) to CH2M HILL Hanford Group, Inc. The CLS carried out the laboratory effort under Contract Number 21065, release Number 30. This report extracts the more pertinent aspects of the laboratory effort

LABORATORY STUDY FOR THE REDUCTION OF CHROME (VI) TO CHROME (III) USING SODIUM METABISULFITE UNDER ACIDIC CONDITIONS

Energy Technology Data Exchange (ETDEWEB)

DUNCAM JB; GUTHRIE MD; LUECK KJ; AVILA M

2007-07-18

This report describes the results from RPP-PLAN-32738, 'Test Plan for the Effluent Treatment Facility to Reduce Chrome(VI) to Chrome(I1I) in the Secondary Waste Stream', using sodium metabisulfite. Appendix A presents the report as submitted by the Center for Laboratory Sciences (CLS) to CH2M HILL Hanford Group, Inc. The CLS carried out the laboratory effort under Contract Number 21065, release Number 30. This report extracts the more pertinent aspects of the laboratory effort.

Monophasic Synovial Sarcoma Presenting as Mitral Valve Obstruction

Science.gov (United States)

Chokesuwattanaskul, Warangkana; Terrell, Jason; Jenkins, Leigh Ann

2010-01-01

We report the case of a 26-year-old man who experienced progressive left-sided chest pain and 2 episodes of near-syncope. Studies revealed a 15-cm mass in the upper left lung, a 10-cm mass in the medial base of the left lung, and a 5-cm left atrial mass that involved the left lung, infiltrated the left pulmonary vein, and prolapsed into the mitral valve, causing intermittent obstruction. The patient underwent surgical excision of the left atrial tumor. Pathologic evaluation confirmed the diagnosis of monophasic synovial sarcoma. To our knowledge, this is only the 3rd report of left atrial invasion and resultant mitral valve obstruction from a synovial sarcoma that infiltrated the pulmonary vein. We believe that this is the 1st documented case of a metastatic left atrial synovial sarcoma in monophasic form. PMID:20844626

Serum 8,12-iso-iPF2α-VI isoprostane marker of oxidative damage and cognition deficits in children with konzo.

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Bumoko G Makila-Mabe

Full Text Available We sought to determine whether motor and cognitive deficits associated with cassava (food cyanogenic poisoning were associated with high concentrations of F2-isoprostanes, well-established indicators of oxidative damage. Concentrations of serum F2-isoprostanes were quantified by LC-MS/MS and anchored to measures of motor proficiency and cognitive performance, which were respectively assessed through BOT-2 (Bruininks/Oseretsky Test, 2nd Edition and KABC-II (Kaufman Assessment Battery for Children, 2nd edition testing of 40 Congolese children (21 with konzo and 19 presumably healthy controls, overall mean age (SD: 9.3 (3.2 years. Exposure to cyanide was ascertained by concentrations of its main metabolite thiocyanate (SCN in plasma and urine. Overall, SCN concentrations ranged from 91 to 325 and 172 to 1032 µmol/l in plasma and urine, respectively. Serum isoprostanes ranged from 0.1 to 0.8 (Isoprostane-III, 0.8 to 8.3 (total Isoprostane-III, 0.1 to 1.5 (Isoprostane-VI, 2.0 to 9.0 (total Isoprostane-VI, or 0.2 to 1.3 ng/ml (8,12-iso-iPF2α-VI isoprostane. Children with konzo poorly performed at the BOT-2 and KABC-II testing relative to presumably healthy children (p<0.01. Within regression models adjusting for age, gender, motor proficiency, and other biochemical variables, 8,12-iso-iPF2α-VI isoprostane was significantly associated with the overall cognitive performance (β = -32.36 (95% CI: -51.59 to -13.03; P<0.001. This model explained over 85% of variation of the KABC-II score in children with konzo, but was not significant in explaining the motor proficiency impairment. These findings suggest that cognitive deficits and, possibly, brain injury associated with cassava poisoning is mediated in part by oxidative damage in children with konzo. 8,12-iso-iPF2α-VI isoprostane appears to be a good marker of the neuropathogenic mechanisms of konzo and may be used to monitor the impact of interventional trials to prevent the neurotoxic effects of

Bianchi VI0 and III models: self-similar approach

International Nuclear Information System (INIS)

Belinchon, Jose Antonio

2009-01-01

We study several cosmological models with Bianchi VI 0 and III symmetries under the self-similar approach. We find new solutions for the 'classical' perfect fluid model as well as for the vacuum model although they are really restrictive for the equation of state. We also study a perfect fluid model with time-varying constants, G and Λ. As in other studied models we find that the behaviour of G and Λ are related. If G behaves as a growing time function then Λ is a positive decreasing time function but if G is decreasing then Λ 0 is negative. We end by studying a massive cosmic string model, putting special emphasis in calculating the numerical values of the equations of state. We show that there is no SS solution for a string model with time-varying constants.

Extraction of U(VI), Th(IV), and La(III) from acidic streams and geological samples using AXAD-16-POPDE polymer

Energy Technology Data Exchange (ETDEWEB)

Prabhakaran, D.; Subramanian, M.S. [Indian Institute of Technology, Department of Chemistry, Chennai 600 036 (India)

2004-10-01

A new chromatographic extraction method has been developed using Amberlite XAD-16 (AXAD-16) resin chemically modified with (3-hydroxyphosphinoyl-2-oxo-propyl)phosphonic acid dibenzyl ester (POPDE). The chemically modified polymer was characterized by {sup 13}C CPMAS and {sup 31}P solid-state NMR, Fourier Transform-NIR-FIR-Raman spectroscopy, CHNPS elemental analysis, and thermogravimetric analysis. Extraction studies performed for U(VI), Th(IV), and La(III) showed good distribution ratio (D) values of approximately 10{sup 3}, even under high acidities (1-4 M). Various physiochemical parameters that influence the quantitative metal ion extraction were optimized by static and dynamic methods. Data obtained from kinetic studies revealed that a time duration of {<=}10 min was sufficient to achieve complete metal ion extraction. Maximum metal sorption capacity values under optimum pH conditions were found to be 1.38, 1.33, and 0.75 mmol g{sup -1} for U(VI), Th(IV), and La(III), respectively. Interference studies performed in the presence of concentrated diverse ions and electrolyte species showed quantitative analyte recovery with lower limits of analyte detection being 10 and 20 ng cm{sup -3} for U(VI) and both Th(IV) and La(III), respectively. Sample breakthrough studies performed on the extraction column showed an enrichment factor value of 330 for U(VI) and 270 for Th(IV) and La(III), respectively. Analyte desorption was effective using 15 cm{sup 3} of 1 M (NH{sub 4}){sub 2}CO{sub 3} with >99.8% analyte recovery. The analytical applicability of the developed resin was tested with synthetic mixtures mimicking nuclear spent fuels, seawater compositions and real water and geological samples. The rsd values of the data obtained were within 5.2%, thereby reflecting the reliability of the developed method. (orig.)

Ordered perovskites with cationic vacancies. 10. Compounds of type A/sub 2/sup(II)Bsub(1/4)sup(II)Bsub(1/2)sup(III)vacantsub(1/4)Msup(VI)O/sub 6/ equal to A/sub 8/sup(II)Bsup(II)B/sub 2/sup(III)vacantM/sub 4/sup(VI)O/sub 24/ with Asup(II), Bsup(II) = Ba, Sr, Ca and Msup(VI) = U, W

Energy Technology Data Exchange (ETDEWEB)

Betz, B; Schittenhelm, H J; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1982-01-01

Perovskites of type Ba/sub 8/Bsup(II)B/sub 2/sup(III)vacantU/sub 4/sup(VI)O/sub 24/ show polymorphic phase transformations of order disorder type. An 1:1 ordered orthorhombic HT form is transformed into a higher ordered LT modification with a fourfold cell content (four formula units Ba/sub 8/Bsup(II)B/sub 2/sup(III)vacantU/sub 4/O/sub 24/), compared to cubic 1:1 ordered perovskites A/sub 2/BMO/sub 6/. In the series Ba/sub 8/BaB/sub 2/sup(III)vacantW/sub 4/O/sub 24/ and Sr/sub 8/SrB/sub 2/sup(III)vacantW/sub 4/O/sub 24/ different ordering phenomena are observed. In comparison with 1:1 ordered cubic perovskites A/sub 2/BMO/sub 6/, the cell contains eight formula units A/sub 8/sup(II)Bsup(II) B/sub 2/sup(III)vacantW/sub 4/O/sub 2/4. The higher ordered cells with Usup(VI) and Wsup(VI) are face centered, which has its origin in an ordering of cationic vacancies.

Investigation of Clostridium botulinum group III's mobilome content.

Science.gov (United States)

Woudstra, Cédric; Le Maréchal, Caroline; Souillard, Rozenn; Anniballi, Fabrizio; Auricchio, Bruna; Bano, Luca; Bayon-Auboyer, Marie-Hélène; Koene, Miriam; Mermoud, Isabelle; Brito, Roseane B; Lobato, Francisco C F; Silva, Rodrigo O S; Dorner, Martin B; Fach, Patrick

2018-02-01

Clostridium botulinum group III is mainly responsible for botulism in animals. It could lead to high animal mortality rates and, therefore, represents a major environmental and economic concern. Strains of this group harbor the botulinum toxin locus on an unstable bacteriophage. Since the release of the first complete C. botulinum group III genome sequence (strain BKT015925), strains have been found to contain others mobile elements encoding for toxin components. In this study, seven assays targeting toxin genes present on the genetic mobile elements of C. botulinum group III were developed with the objective to better characterize C. botulinum group III strains. The investigation of 110 C. botulinum group III strains and 519 naturally contaminated samples collected during botulism outbreaks in Europe showed alpha-toxin and C2-I/C2-II markers to be systematically associated with type C/D bont-positive samples, which may indicate an important role of these elements in the pathogenicity mechanisms. On the contrary, bont type D/C strains and the related positive samples appeared to contain almost none of the markers tested. Interestingly, 31 bont-negative samples collected on farms after a botulism outbreak revealed to be positive for some of the genetic mobile elements tested. This suggests loss of the bont phage, either in farm environment after the outbreak or during laboratory handling. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

International Nuclear Information System (INIS)

Narin, Ibrahim; Kars, Ayse; Soylak, Mustafa

2008-01-01

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

Identification of Near-infrared [Se iii] and [Kr vi] Emission Lines in Planetary Nebulae

Energy Technology Data Exchange (ETDEWEB)

Sterling, N. C.; Mashburn, A. L. [Department of Physics, University of West Georgia, 1601 Maple Street, Carrollton, GA 30118 (United States); Madonna, S.; García-Rojas, J.; Luridiana, V. [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain); Butler, K. [Institut für Astronomie und Astrophysik, Scheinerstr. 1, D-81679 München (Germany); Morisset, C. [Instituto de Astronomía, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20164, 04510 (Mexico); Roederer, I. U., E-mail: nsterlin@westga.edu, E-mail: awhite15@my.westga.edu, E-mail: vale@iaa.es, E-mail: smadonna@iac.es, E-mail: jogarcia@iac.es, E-mail: butler@usm.uni-muenchen.de, E-mail: chris.morisset@gmail.com, E-mail: iur@umich.edu [Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109 (United States)

2017-05-10

We identify [Se iii] 1.0994 μ m in the planetary nebula (PN) NGC 5315 and [Kr vi] 1.2330 μ m in three PNe from spectra obtained with the Folded-Port InfraRed Echellette (FIRE) spectrometer on the 6.5 m Baade Telescope. Se and Kr are the two most widely detected neutron-capture elements in astrophysical nebulae, and can be enriched by s -process nucleosynthesis in PN progenitor stars. The detection of [Se iii] 1.0994 μ m is particularly valuable when paired with observations of [Se iv] 2.2864 μ m, as it can be used to improve the accuracy of nebular Se abundance determinations, and allows Se ionization correction factor (ICF) schemes to be empirically tested for the first time. We present new effective collision strength calculations for Se{sup 2+} and Kr{sup 5+}, which we use to compute ionic abundances. In NGC 5315, we find that the Se abundance computed from Se{sup 3+}/H{sup +} is lower than that determined with ICFs that incorporate Se{sup 2+}/H{sup +}. We compute new Kr ICFs that take Kr{sup 5+}/H{sup +} into account, by fitting correlations found in grids of Cloudy models between Kr ionic fractions and those of more abundant elements, and use these to derive Kr abundances in four PNe. Observations of [Se iii] and [Kr vi] in a larger sample of PNe, with a range of excitation levels, are needed to rigorously test the ICF prescriptions for Se and our new Kr ICFs.

La(III) sorption studies on poly(dibenzo-18-crown-6) for the sequential separation of La(III), Th(IV) and U(VI) in L-arginine

International Nuclear Information System (INIS)

Sabale, Sandip; Nikam, Gurunath; Mohite, B.S.

2010-01-01

Poly(dibenzo-18-crown-6) is used as a stationary phase to study the sorption behavior of La(III) in L-arginine medium. The quantitative adsorption of La(III) was found at 1 x 10 -4 to 1 x 10 -6 M L-arginine. 1.0-8.0 M HCl, 0.5-8.0 M HBr and HClO 4 were found to be an efficient eluents for La(III). The capacity of crown polymer for La(III) was found to be 1.37±0.01 mmol/g. The tolerance limit of various cations and anions for La(III) was determined. La(III) was quantitatively separated from other metal ions in binary as well as multicomponent mixtures. The study was extended to sequential separation of La(III), U(VI) and Th(IV). The good separation yields were obtained and have good reproducibility (±2%). The method incorporates the determination of La(III) in real sample. The method is simple, rapid and selective. (author)

Quantifying Cr(VI) Production and Export from Serpentine Soil of the California Coast Range.

Science.gov (United States)

McClain, Cynthia N; Fendorf, Scott; Webb, Samuel M; Maher, Kate

2017-01-03

Hexavalent chromium (Cr(VI)) is generated in serpentine soils and exported to surface and groundwaters at levels above health-based drinking water standards. Although Cr(VI) concentrations are elevated in serpentine soil pore water, few studies have reported field evidence documenting Cr(VI) production rates and fluxes that govern Cr(VI) transport from soil to water sources. We report Cr speciation (i) in four serpentine soil depth profiles derived from the California Coast Range serpentinite belt and (ii) in local surface waters. Within soils, we detected Cr(VI) in the same horizons where Cr(III)-minerals are colocated with biogenic Mn(III/IV)-oxides, suggesting Cr(VI) generation through oxidation by Mn-oxides. Water-extractable Cr(VI) concentrations increase with depth constituting a 7.8 to 12 kg/km 2 reservoir of Cr(VI) in soil. Here, Cr(VI) is produced at a rate of 0.3 to 4.8 kg Cr(VI)/km 2 /yr and subsequently flushed from soil during water infiltration, exporting 0.01 to 3.9 kg Cr(VI)/km 2 /yr at concentrations ranging from 25 to 172 μg/L. Although soil-derived Cr(VI) is leached from soil at concentrations exceeding 10 μg/L, due to reduction and dilution during transport to streams, Cr(VI) levels measured in local surface waters largely remain below California's drinking water limit.

Cerium(III) molybdate nanoparticles: Synthesis, characterization and radionuclides adsorption studies

Energy Technology Data Exchange (ETDEWEB)

Yousefi, Taher, E-mail: Taher_yosefy@yahoo.com [NFCRS, Nuclear Science and Technology Institute, Kargher Ave, Tehran (Iran, Islamic Republic of); Tarbiat Moallem University, Mofatteh Ave, Tehran (Iran, Islamic Republic of); Khanchi, Ali Reza; Ahmadi, Seyed Javad [NFCRS, Nuclear Science and Technology Institute, Kargher Ave, Tehran (Iran, Islamic Republic of); Rofouei, Mohamad Kazem [Tarbiat Moallem University, Mofatteh Ave, Tehran (Iran, Islamic Republic of); Yavari, Ramin; Davarkhah, Reza; Myanji, Behzad [NFCRS, Nuclear Science and Technology Institute, Kargher Ave, Tehran (Iran, Islamic Republic of)

2012-05-15

Highlights: Black-Right-Pointing-Pointer A new inorganic nanoparticles with average size about 40 nm were synthesized by chemical method. Black-Right-Pointing-Pointer The morphology studies reveal existing nanowires among dense nanoparticles. Black-Right-Pointing-Pointer Investigation shows it has high stability in rough media and high affinity for Cs(I), U(VI), and Th(IV). Black-Right-Pointing-Pointer It was used for adsorption of radionuclides and removal of {sup 134}Cs from real sample. Black-Right-Pointing-Pointer These findings are important for evaluating human and environmental risk assessment. - Abstract: Cerium(III) molybdate nanostructure with average size about 40 nm was prepared by adding cerium(III) chloride and ammonium molybdate solutions under varying conditions. The product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA) and Brunauere Emmette Teller (BET) techniques. Ion exchange capacity of the sample for potassium ion and distribution coefficients (K{sub d}) for 23 metal ions were determined, the K{sub d} values for Tl(I), Pb(II), Th(IV), U(VI), and Cs(I) ions were found to be sufficiently high for their removal from various effluents. The adsorption behavior of the sample towards Cs(I){sub 134} species were studied. Finally, the binary separation of Dy(III)-U(VI), Sm(III)-Th(IV) and Cs(I)-Rb(I) and removal of Cs(I){sub 134} from the real sample were successfully achieved.

Monophasic Pulsed 200-?A Current Promotes Galvanotaxis With Polarization of Actin Filament and Integrin ?2?1 in Human Dermal Fibroblasts

OpenAIRE

Uemura, Mikiko; Maeshige, Noriaki; Koga, Yuka; Ishikawa-Aoyama, Michiko; Miyoshi, Makoto; Sugimoto, Masaharu; Terashi, Hiroto; Usami, Makoto

2016-01-01

Objective: The monophasic pulsed microcurrent is used to promote wound healing, and galvanotaxis regulation has been reported as one of the active mechanisms in the promotion of tissue repair with monophasic pulsed microcurrent. However, the optimum monophasic pulsed microcurrent parameters and intracellular changes caused by the monophasic pulsed microcurrent have not been elucidated in human dermal fibroblasts. The purpose of this study was to investigate the optimum intensity for promoting...

Role of an organic carbon-rich soil and Fe(III) reduction in reducing the toxicity and environmental mobility of chromium(VI) at a COPR disposal site.

Science.gov (United States)

Ding, Weixuan; Stewart, Douglas I; Humphreys, Paul N; Rout, Simon P; Burke, Ian T

2016-01-15

Cr(VI) is an important contaminant found at sites where chromium ore processing residue (COPR) is deposited. No low cost treatment exists for Cr(VI) leaching from such sites. This study investigated the mechanism of interaction of alkaline Cr(VI)-containing leachate with an Fe(II)-containing organic matter rich soil beneath the waste. The soil currently contains 0.8% Cr, shown to be present as Cr(III)(OH)3 in EXAFS analysis. Lab tests confirmed that the reaction of Cr(VI) in site leachate with Fe(II) present in the soil was stoichiometrically correct for a reductive mechanism of Cr accumulation. However, the amount of Fe(II) present in the soil was insufficient to maintain long term Cr(VI) reduction at historic infiltration rates. The soil contains a population of bacteria dominated by a Mangroviflexus-like species, that is closely related to known fermentative bacteria, and a community capable of sustaining Fe(III) reduction in alkaline culture. It is therefore likely that in situ fermentative metabolism supported by organic matter in the soil produces more labile organic substrates (lactate was detected) that support microbial Fe(III) reduction. It is therefore suggested that addition of solid phase organic matter to soils adjacent to COPR may reduce the long term spread of Cr(VI) in the environment. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Sorption of U(VI) and Am(III) on Eucalyptus Biochar

International Nuclear Information System (INIS)

Mishra, Vijayakriti; Sureshkumar, M.K.; Kaushik, C.P.

2016-01-01

Biochar is partially oxidized residues from substrates of biological origin. Due to their binding properties with various organic and inorganic pollutants, these materials are widely studied for pollutant abatement both in field studies and laboratory investigations. Though large quantity of information is available on the use of biochar of various origin for heavy metals, studies pertaining to their use in radionuclide sorption are scarce in literature. Here we are reporting the sorption characteristics of U(VI) and Am(III) on to eucalyptus biochar as a function of various operating parameters such as solution pH, initial metal ion concentration, contact time and ionic strength of the medium. Overall the present studies shows that eucalyptus biochar is a suitable sorbent for the sorption of heavy radionuclides from aqueous solutions

Effect of genotype, Cr(III and Cr(VI on plant growth and micronutrient status in Silene vulgaris (Moench

Directory of Open Access Journals (Sweden)

A. E. Pradas-del-Real

2013-06-01

Full Text Available Chromium released into the environment from industrial activities has become an important environmental concern. Silene vulgaris has been proven to be tolerant to many heavy metals, so it is considered an interesting species in the revegetation and restoration of polluted soils, but no information is available about its response to Cr. The objective of this work was to study uptake and influence on plant growth of Cr(III and Cr(VI in six genotypes (four hermaphrodites and two females of S. vulgaris from different sites of Madrid (Spain. Plants were treated for 12 days with 60 µM of Cr(III or Cr(VI in semihydroponics. Dry weights, soil-plant analysis development values (SPAD reading with chlorophylls and micronutrient and total Cr concentrations were determined. Metal uptake was higher in presence of Cr(VI than of Cr(III and poorly translocated to the shoots. In both cases S. vulgaris did not show visual toxicity symptoms, biomass reduction, or differences among SPAD values as consequence of Cr additions. However genotypes SV36 and SV38 showed Fe and Mn imbalance. This is the first report on the relatively good performance of hermaphrodite and female S. vulgaris genotypes in Cr uptake and physiological traits, but further studies will be necessary to elucidate the mechanisms by which the gender may influence these variables. S. vulgaris presented high diversity at genotypic level; the treatment with hexavalent Cr increased the differences among genotypes so the use of cuttings from an homogeneous genotype seems to be an adequate method for the study of this species.

Terapia de reposição enzimática para as mucopolissacaridoses I, II e VI: recomendações de um grupo de especialistas brasileiros Enzyme replacement therapy for mucopolysaccharidoses I, II and VI: recommendations from a group of Brazilian F experts

Directory of Open Access Journals (Sweden)

Roberto Giugliani

2010-01-01

developed and was approved for clinical use in MPS I, II and VI in the first decade of the 21st century. The authors of this paper are convinced that a better future for patients affected by mucopolysaccharidoses depends upon identifying, understanding and appropriately managing the multisystemic manifestations of these diseases. This includes the provision of support measures (which should be part of regular multidisciplinary care of these patients and of specific therapies. Although inhibition of synthesis of GAG and the recovery of enzyme activity with small molecules also may play a role in the management of MPS, the breakthrough is the currently available intravenous ERT. ERT radically changed the setting for treatment of mucopolysaccharidosis I, II and VI in the last decade., Benefits can even be extended soon to MPS IV A (ERT for this condition is already in clinical development, with prediction for treatment of MPS III A and the cognitive deficit in MPS II by administration of the enzyme directly into the central nervous system (CNS. A large number of Brazilian services, from all regions of the country, already have experience with ERT for MPS I, II and VI. This experience was gained not only by treating patients but also with the participation of some groups in clinical trials involving ERT for these conditions. Summing up the three types of MPS, more than 250 patients have already been treated with ERT in Brazil. The experience of professionals coupled to the data available in international literature, allowed us to elaborate this document, produced with the goal of bringing together and harmonize the information available for the treatment of these severe and progressive diseases, which, fortunately, are now treatable, a situation which bring new perspectives for Brazilian patients, affected by these conditions.

Epidemiological and microbiological investigation of a large outbreak of monophasic Salmonella Typhimurium 4,5,12:i:- in schools associated with imported beef in Poitiers, France, October 2010.

Science.gov (United States)

Raguenaud, M E; Le Hello, S; Salah, S; Weill, F X; Brisabois, A; Delmas, G; Germonneau, P

2012-10-04

An outbreak due to the emerging monophasic Salmonella Typhimurium 4,5,12:i:- occurred in four schools in Poitiers in October 2010. Food trace-back investigation led to the identification of beef burgers as the cause of the outbreak and their subsequent withdrawal. The Institute for Public Health Surveillance conducted a retrospective epidemiological investigation to assess the extent of the outbreak and describe cases. Self-administered questionnaires were completed by students and personnel attending each of the four schools affected. Clinical cases were defined as anyone having eaten at the school when the beef burgers were served and reporting diarrhoea or fever with at least one digestive symptom (nausea, vomiting or abdominal pain), within five days after the incriminated school meal or with unknown date of onset within a 15-day period after the incriminated school meal. Of 1,559 persons exposed, 554 clinical cases were identified corresponding to an overall attack rate of 35.5%. Of 554 clinical cases, a total of 286 (53%) sought medical care and 31 (6%) were hospitalised for more than 24 hours. This multi-school outbreak is one of the biggest food-borne outbreaks of monophasic Salmonella Typhimurium 4,5,12:i:- described in France. Prompt notification of cases and rapid identification and withdrawal of the incriminated batch of beef burgers was crucial to limit the extension of this outbreak.

Voltammetric study of chromium(VI)-ammonia/ammonium chloride solutions in the presence of dimethylglyoxime

International Nuclear Information System (INIS)

Ginzburg, V.G.; Salikhdzhanova, R.M.F.

1987-01-01

The authors believed complexation to be possible in the system Cr(VI)-dimethylglyoxime (DMG, H 2 D) by reduction of Cr(VI) to Cr(III) on a mercury electrode. The DMG can be used in chromium voltammetry and is promising for a number of reasons: The Cr(III) has an affinity for donor nitrogen atoms in the DMG molecule. Insertion of the H 2 D into the inner sphere of the complex is expected to weaken the bond between the Cr(III) and the hydroxyl group, slow down formation of the insoluble hydroxide Cr(OH) 3 , and lower the rate of the electrode reaction Cr(III) → Cr(II). Molecules of H 2 D adsorb on a mercury electrode. It is therefore possible to accelerate the electrode process by including adsorptive preconcentration of the chromium and thus lowering its detection limit. This paper reports the voltammetric behavior of the system Cr(VI)-DMG-NH 4 + (proton donor) for the purpose of lowering the chromium detection limit

Solvent extraction of uranium(VI), plutonium(VI) and americium(III) with HTTA/HPMBP using mono- and bi-functional neutral donors. Synergism and thermodynamics

International Nuclear Information System (INIS)

Pai, S.A.; Lohithakshan, K.V.; Mithapara, P.D.; Aggarwal, S.K.

2000-01-01

Synergistic extraction of hexavalent uranium and plutonium as well as trivalent americium was studied in HNO 3 with thenoyl, trifluoro-acetone (HTTA)/1-phenyl, 3-methyl, 4-benzoyl pyrazolone-5 (HPMBP) in combination with neutral donors viz. DPSO, TBP, TOPO (mono-functional) and DBDECMP, DHDECMP, CMPO (bi-functional) with wide basicity range using benzene as diluent. A linear correlation was observed when the equilibrium constant log Ks for the organic phase synergistic reaction of both U(VI) and Pu(VI) with either of the chelating agents HTTA or HPMBP was plotted vs. the basicity (log Kh) of the donor (both mono- and bi-functional) indicating bi-functional donors also behave as mono-functional. This was supported by the thermodynamic data (ΔG 0 , ΔH 0 , ΔS 0 ) obtained for these systems. The organic phase adduct formation reactions were identified for the above systems from the thermodynamic data. In the Am(III) HTTA system log K s values of bi-functional donors were found to be very high and deviate from the linear plot (log K s vs. log K h ) obtained for mono-functional donors, indicating that they function as bi-functional for the Am(III)/HTTA) system studied. This was supported by high +ve ΔS 0 values obtained for this system. (author)

Reduction and Removal of Chromium VI in Water by Powdered Activated Carbon

Directory of Open Access Journals (Sweden)

Yanan Chen

2018-02-01

Full Text Available Cr adsorption on wood-based powdered activated carbon (WPAC was characterized by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS. The highest Cr(VI adsorption (40.04% was obtained under acidic conditions (pH 3, whereas Cr removal at pH 10 was only 0.34%. The mechanism of Cr(VI removal from aqueous solutions by WPAC was based on the reduction of Cr(VI to Cr(III with the concomitant oxidation of C-H and C-OH to C-OH and C=O, respectively, on the surface of WPAC, followed by Cr(III adsorption. Raman spectroscopy revealed a change in the WPAC structure in terms of the D/G band intensity ratio after Cr(VI adsorption. SEM-EDS analysis showed that the oxygen/carbon ratio on the WPAC surface increased from 9.85% to 17.74%. This result was confirmed by XPS measurements, which showed that 78.8% of Cr adsorbed on the WPAC surface was in the trivalent state. The amount of oxygen-containing functional groups on the surface increased due to the oxidation of graphitic carbons to C-OH and C=O groups.

Multisensor system for determination of iron(II), iron(III), uranium(VI) and uranium(IV) in complex solutions

International Nuclear Information System (INIS)

Legin, A.V.; Seleznev, B.L.; Rudnitskaya, A.M.; Vlasov, Yu.G.; Tverdokhlebov, S.V.; Mack, B.; Abraham, A.; Arnold, T.; Baraniak, L.; Nitsche, H.

1999-01-01

Development and analytical evaluation of a multisensor system based on the principles of 'electronic tongue' for the determination of low contents of uranium(VI), uranium(IV), iron(II) and iron(III) in complex aqueous media have been carried out. A set of 29 different chemical sensors on the basis of all- solid-state crystalline and vitreous materials with enhanced electronic conductivity and redox and ionic cross-sensitivity have been incorporated into the sensor array. Multidimensional data have been processed by pattern recognition methods such as artificial neural networks and partial least squares. It has been demonstrated that Fe(II) and Fe(III) contents in the range from 10 -7 to 10 -4 mol L -1 of total iron concentration can be determined with the average precision of about 25 %. U(VI) and U(IV) contents can been determined with the average precision of 10-40% depending on the concentration. The developed multisensor system can be applied in future for the analysis of mining and borehole waters as well other contaminated natural media, including on-site measurements. (author)

Multisensor system for determination of iron(II), iron(III) and uranium(VI) in complex solutions

International Nuclear Information System (INIS)

Legin, A.V.; Seleznev, B.L.; Rudnitskaya, A.M.; Vlasov, Yu.G.

1998-01-01

The aim of the present paper is the development and analytical evaluation of a multisensor system for determination of low content of iron(II), iron(III) and uranium(VI) in complex aqueous media. Sensor array included sensors on the basis of chalcogenide vitreous materials with redox and ionic cross-sensitivities, crystalline silver sulphide electrode, noble metal electrodes Pt, Au, Ag and redox sensor on the basis of oxide glass. Potentiometric measurements have been taken in a conventional electrochemical cell vs. a standard Ag/AgCl reference electrode. All measurements have been taken at room temperature. Calibration solutions contained UO 2 (NO 3 ) 2 in concentration range 10 -6 -1,610 -5 mol/L, K 3 Fe(CN) 6 and K 4 Fe(CN) 6 or FeSO 4 (NH 4 ) 2 SO 4 and FeCl 3 , with the ratio of Fe(II)/Fe(III) concentration from 100:1 to 1:100, the total concentration of Fe was 10 -4 and 10 -5 mol/L. All solutions have been made on the background electrolyte of calcium and magnesium chlorides and sulphates with the fixed content of 5-27 mmol/L of each component which is a typical one for groundwater or mining water. Sensor potentials have been processed by a back-propagation artificial neural net. Average error of determination of Fe(II) and Fe(III) is about 20 %, of uranium(VI) - 40 %. It was found that sensitivity of the sensor array to iron and uranium is irrespective of the chemical form of these species

Bianchi VI{sub 0} and III models: self-similar approach

Energy Technology Data Exchange (ETDEWEB)

Belinchon, Jose Antonio, E-mail: abelcal@ciccp.e [Departamento de Fisica, ETS Arquitectura, UPM, Av. Juan de Herrera 4, Madrid 28040 (Spain)

2009-09-07

We study several cosmological models with Bianchi VI{sub 0} and III symmetries under the self-similar approach. We find new solutions for the 'classical' perfect fluid model as well as for the vacuum model although they are really restrictive for the equation of state. We also study a perfect fluid model with time-varying constants, G and LAMBDA. As in other studied models we find that the behaviour of G and LAMBDA are related. If G behaves as a growing time function then LAMBDA is a positive decreasing time function but if G is decreasing then LAMBDA{sub 0} is negative. We end by studying a massive cosmic string model, putting special emphasis in calculating the numerical values of the equations of state. We show that there is no SS solution for a string model with time-varying constants.

An electrochemical study of U(VI) and Cr(VI) in molten borates

International Nuclear Information System (INIS)

Brigaudeau, M.; Gregori de Pinochet, I. de

1977-01-01

The electrochemical reduction of U(VI) and Cr(VI), in molten Na 2 B 4 O 7 at 800 deg C was studied by means of linear sweep voltammetry, and chronopotentiometry. The reduction of U(VI) to U(V) proceeded reversibly at a platinum electrode. The diffusion coefficient for the U(VI) species at 800 deg C was 4.10 -7 cm 2 .s -1 . The activation energy of diffusion was (34,8 +- 0,8) kcal. mole -1 . Electrochemical studies of Cr(VI) at 800 0 C reveal a two-step reduction process at a platinum electrode. Only the voltammogram for the first step charge transfer process was studied. Analysis indicated that Cr(VI) is reversibly reduced to Cr(III) at a platinum electrode. The diffusion coefficient for Cr(VI) at 800 0 C is 1,9.10 -7 cm 2 .s -1 [fr

Sediment studies of the biological factors controlling the reduction of U(VI)

International Nuclear Information System (INIS)

Lovley, Derek R.

2004-01-01

Studies were conducted primarily with sediments, both in laboratory incubations and in a field experiment, with supporting studies with pure cultures. To our knowledge the sediment studies were the first on microbial U(VI) reduction in actual uranium-contaminated subsurface sediments, under conditions that mimic those found in situ. Important findings included: (1) U(VI) reduction is a biotic process in subsurface sediments. (2) U(VI) reduction can be stimulated most effectively with the addition of acetate. Although it had been speculated that microbial U(VI) reduction might be capable of this type of environmental remediation ever since the discovery of microbial U(VI) reduction, this had not been previously demonstrated under environmentally relevant conditions. (3) U(VI) is reduced concurrently with Fe(III) and prior to sulfate reduction. U(VI) and Fe(III) reduction proceeded concurrently, accompanied by a dramatic enrichment in organisms in the Geobacteraceae. Sulfate-reducing microorganisms do not appear to be important components of the microbial community reducing U(VI) in these subsurface sediments. (4) Nitrate has important influences on U(VI) reduction. Nitrate inhibits the reduction of metals until nitrate is depleted. Fe(III)-reducing microorganisms such as Geobacter metallireducens and Desulfitobacterium species can oxidize Fe(II) with the reduction of nitrate which is an important consideration because our previous studies have demonstrated that freshly precipitated Fe(III) oxides can reoxidize U(IV) to U(VI). The discovery that G. metallireducens can ''run backwards'' and oxidize U(IV) when nitrate is present reveals another mechanism preventing precipitation of U(IV) in the presence of nitrate as well as potential novel strategy for removing uranium from the subsurface after a site has been remediated. (5) Importance of understanding Fe(III) forms available for microbial reduction. Fe(III) is orders of magnitude more abundant than U(VI) as an

Synthesis and crystal structure of three new quaternary compounds in the system (Cu-III-Se{sub 2}){sub 1-x}ZnSe{sub x} (III = Al, Ga, In), formed by Zn incorporation in Cu-III-Se{sub 2} chalcopyrite s

Energy Technology Data Exchange (ETDEWEB)

Delgado, G. E. [Universidad de Los Andes, Facultad de Ciencias, Departamento de Quimica, Laboratorio de Cristalografia, 5101 Merida (Venezuela, Bolivarian Republic of); Grima G, P.; Quintero, M., E-mail: gerzon@ula.ve [Universidad de Los Andes, Facultad de Ciencias, Departamento de Fisica, Centro de Estudios de Semiconductores, 5101 Merida (Venezuela, Bolivarian Republic of)

2016-11-01

The crystal structure of the chalcogenide alloys CuZnAlSe{sub 3}, CuZnCaSe{sub 3} and CuZnInSe{sub 3}, new members of the system I-II-III-VI{sub 3}, were characterized using X-ray powder diffraction data. All materials crystallize in the tetragonal space group P{sub -4} 2{sub c} (N 112) with a CuFeInSe{sub 3}- type structure. (Author)

Gene expression correlates with process rates quantified for sulfate- and Fe(III-reducing bacteria in U(VI-contaminated sediments

Directory of Open Access Journals (Sweden)

Denise M Akob

2012-08-01

Full Text Available Though iron- and sulfate-reducing bacteria are well known for mediating uranium(VI reduction in contaminated subsurface environments, quantifying the in situ activity of the microbial groups responsible remains a challenge. The objective of this study was to demonstrate the use of quantitative molecular tools that target mRNA transcripts of key genes related to Fe(III and sulfate reduction pathways in order to monitor these processes during in situ U(VI remediation in the subsurface. Expression of the Geobacteraceae-specific citrate synthase gene (gltA and the dissimilatory (bisulfite reductase gene (dsrA, were correlated with the activity of iron- or sulfate-reducing microorganisms, respectively, under stimulated bioremediation conditions in microcosms of sediments sampled from the U.S. Department of Energy’s Oak Ridge Integrated Field Research Challenge (OR-IFRC site at Oak Ridge, Tennessee. In addition, Geobacteraceae-specific gltA and dsrA transcript levels were determined in parallel with the predominant electron acceptors present in moderately and highly contaminated subsurface sediments from the OR-IFRC. Phylogenetic analysis of the cDNA generated from dsrA mRNA, sulfate-reducing bacteria-specific 16S rRNA, and gltA mRNA identified activity of specific microbial groups. Active sulfate reducers were members of the Desulfovibrio, Desulfobacterium, and Desulfotomaculum genera. Members of the subsurface Geobacter clade, closely related to uranium-reducing Geobacter uraniireducens and Geobacter daltonii, were the metabolically-active iron-reducers in biostimulated microcosms and in situ core samples. Direct correlation of transcripts and process rates demonstrated evidence of competition between the functional guilds in subsurface sediments. We further showed that active populations of Fe(III-reducing bacteria and sulfate-reducing bacteria are present in OR-IFRC sediments and are good potential targets for in situ bioremediation.

Vi, de civiliserede

DEFF Research Database (Denmark)

Nyemann, Dorthe

2016-01-01

Vi har i årtier troet på, at mennesker under de rette omstændigheder kan lykkes med at leve i fred og fordragelighed med hinanden. Skal vi til at erkende, at også vores samfundsstrukturer kun er en tynd fernis ovenpå et utæmmeligt voldspotentiale og egoisme?......Vi har i årtier troet på, at mennesker under de rette omstændigheder kan lykkes med at leve i fred og fordragelighed med hinanden. Skal vi til at erkende, at også vores samfundsstrukturer kun er en tynd fernis ovenpå et utæmmeligt voldspotentiale og egoisme?...

On-line Speciation of Cr(III) and Cr(VI) by Flow Injection Analysis With Spectrophotometric Detection and Chemometrics

DEFF Research Database (Denmark)

Diacu, Elena; Andersen, Jens Enevold Thaulov

2003-01-01

A flow injection system has been developed, for on-line speciation. of Cr(III) and Cr(VI) by the Diphenylcarbazide (DPC) method with H2O2 oxidation followed by spectrophotometric detection at the 550 nm wavelength. The data thus obtained were subjected to a chemometric analysis (PLS), which showe...

U(VI) adsorption on natural iron-coated sands: comparison of approaches for modeling adsorption on heterogeneous environmental materials

International Nuclear Information System (INIS)

Logue, Brian A.; Smith, Robert W.; Westall, John C.

2004-01-01

Adsorption of U(VI) on 6 samples of natural Fe-rich sands from Oyster, VA was studied over a range of U(VI) concentrations (0.1-100 μM), pH values (3-7.6), and dithionite-citrate-bicarbonate (DCB) extractable amounts of Fe (3.1-12.3 μmol/g). Four modeling approaches were applied to represent the U(VI) adsorption data. Model I was a two-site, diffuse double layer, surface complexation model based on data for synthetic ferrihydrite [Geochim. Cosmochim. Acta 58 (1994) 5465-5478]. Considering the magnitude of approximations necessary for application of the laboratory-based model to natural sands, Model I was surprisingly accurate, as determined by the goodness of fit parameter, χ 2 /N of 53.1-22.2. Model II was based on the reactions and diffuse double layer treatment of Model I, but was calibrated to a portion of U(VI) adsorption data for each sand, and then used to predict adsorption data for the same sand under different experimental conditions. Model II did not increase the accuracy of the predictions made with Model I, χ 2 /N of 42.4-27.6. Models III and IV were four-site affinity spectrum models, without an explicit electric double layer model or explicit surface hydrolysis reactions. Model III was based on a discrete log K spectrum approach, and Model IV was obtained from adjusting all surface stability constants and site concentrations for all surface sites. Models III and IV represented the U(VI) adsorption data with the greatest accuracy, χ 2 /N ranged from 13.8 to 4.4. Model I provides evidence supporting the practice of using pure phase thermodynamic reaction constants for describing the adsorption characteristics of environmentally important sorbents in certain simple cases. Yet, affinity spectrum approaches (Models III and IV) become increasingly important as more accurate interpolation of adsorption data is necessary, the sorbent becomes increasingly complex, or the range of experimental conditions expands

Determination of thermodynamic parameters of Cr(VI) adsorption from aqueous solution onto Agave lechuguilla biomass

Energy Technology Data Exchange (ETDEWEB)

Romero-Gonzalez, J. [Environmental Science and Engineering, University of Texas at El Paso, El Paso, TX 79968 (United States); Peralta-Videa, J.R. [Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968 (United States); Rodriguez, E. [Environmental Science and Engineering, University of Texas at El Paso, El Paso, TX 79968 (United States); Ramirez, S.L. [Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968 (United States); Gardea-Torresdey, J.L. [Environmental Science and Engineering, University of Texas at El Paso, El Paso, TX 79968 (United States) and Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968 (United States)]. E-mail: jgardea@utep.edu

2005-04-15

The temperature dependence of the Cr(VI) bioadsorption and its possible reduction to Cr(III) by Agave lechuguilla biomass were studied. The experimental data obtained in batch experiments at different temperatures were fitted to the Langmuir and Freundlich isotherms to obtain the characteristic parameters of each model. The adsorption equilibrium data fitted well with the Freundlich model. The average model parameters calculated from Freundlich's isotherms (adsorption capacity K{sub F} = 4 . 10{sup -2} mol . g{sup -1} and an average adsorption intensity value n = 13.07) showed that A. lechuguilla can be considered as an effective biomaterial for Cr(VI) removal from aqueous solution. Thermodynamic parameters ({delta}G{sup .}, {delta}H{sup .}, and {delta}S{sup .}) for Cr(VI) adsorption determined in the temperature range from (283 to 313) K suggest that a portion of Cr(VI) may be bound to functional groups on the surface of the adsorbent and then reduced to Cr(III). Additionally, the parameters of the Dubinin-Radushkevick equation indicated that the sorption of chromium species onto lechuguilla biomass mainly proceeds through binding surface functional groups.

Liquid chromatographic studies on the behaviour of Pu(III), Pu(IV) and Pu(VI) on a RP stationary phase in presence of α-hydroxyisobutyric acid as a chelating agent

Energy Technology Data Exchange (ETDEWEB)

Jaison, P.G.; Kumar, Pranaw; Telmore, Vijay M. [Bhabha Atomic Research Centre, Mumbai (India). Fuel Chemistry Division

2017-06-01

Since plutonium possesses multiple oxidation states which can coexist in solution, a method for the identification of these oxidation states is important to understand its chemical processes. Liquid chromatographic studies were carried out to compare the chromatographic behaviour of different oxidation states of Pu in presence of the eluent, α-hydroxyisobutyric acid (HIBA). The three oxidation states of Pu viz. Pu(III), Pu(IV) and Pu(VI) were separated under optimised conditions. It was seen that the presence of the complexing agent influences the equilibrium of Pu(III)/(IV) as well as Pu(IV)/(VI) systems. Pu(III) to Pu(IV) conversion was found to be enhanced by high pH and concentration of HIBA whereas a relatively low pH and high concentration of HIBA promotes the conversion of Pu(VI) to Pu(IV).

Surface complexation modeling of the effects of phosphate on uranium(VI) adsorption

Energy Technology Data Exchange (ETDEWEB)

Romero-Gonzalez, M.R.; Cheng, T.; Barnett, M.O. [Auburn Univ., AL (United States). Dept. of Civil Engeneering; Roden, E.E. [Wisconsin Univ., Madison, WI (United States). Dept. of Geology and Geophysics

2007-07-01

Previous published data for the adsorption of U(VI) and/or phosphate onto amorphous Fe(III) oxides (hydrous ferric oxide, HFO) and crystalline Fe(III) oxides (goethite) was examined. These data were then used to test the ability of a commonly-used surface complexation model (SCM) to describe the adsorption of U(VI) and phosphate onto pure amorphous and crystalline Fe(III) oxides and synthetic goethite-coated sand, a surrogate for a natural Fe(III)-coated material, using the component additivity (CA) approach. Our modeling results show that this model was able to describe U(VI) adsorption onto both amorphous and crystalline Fe(III) oxides and also goethite-coated sand quite well in the absence of phosphate. However, because phosphate adsorption exhibits a stronger dependence on Fe(III) oxide type than U(VI) adsorption, we could not use this model to consistently describe phosphate adsorption onto both amorphous and crystalline Fe(III) oxides and goethite-coated sand. However, the effects of phosphate on U(VI) adsorption could be incorporated into the model to describe U(VI) adsorption to both amorphous and crystalline Fe(III) oxides and goethite-coated sand, at least for an initial approximation. These results illustrate both the potential and limitations of using surface complexation models developed from pure systems to describe metal/radionuclide adsorption under more complex conditions. (orig.)

Surface complexation modeling of the effects of phosphate on uranium(VI) adsorption

International Nuclear Information System (INIS)

Romero-Gonzalez, M.R.; Cheng, T.; Barnett, M.O.; Roden, E.E.

2007-01-01

Previous published data for the adsorption of U(VI) and/or phosphate onto amorphous Fe(III) oxides (hydrous ferric oxide, HFO) and crystalline Fe(III) oxides (goethite) was examined. These data were then used to test the ability of a commonly-used surface complexation model (SCM) to describe the adsorption of U(VI) and phosphate onto pure amorphous and crystalline Fe(III) oxides and synthetic goethite-coated sand, a surrogate for a natural Fe(III)-coated material, using the component additivity (CA) approach. Our modeling results show that this model was able to describe U(VI) adsorption onto both amorphous and crystalline Fe(III) oxides and also goethite-coated sand quite well in the absence of phosphate. However, because phosphate adsorption exhibits a stronger dependence on Fe(III) oxide type than U(VI) adsorption, we could not use this model to consistently describe phosphate adsorption onto both amorphous and crystalline Fe(III) oxides and goethite-coated sand. However, the effects of phosphate on U(VI) adsorption could be incorporated into the model to describe U(VI) adsorption to both amorphous and crystalline Fe(III) oxides and goethite-coated sand, at least for an initial approximation. These results illustrate both the potential and limitations of using surface complexation models developed from pure systems to describe metal/radionuclide adsorption under more complex conditions. (orig.)

75 FR 23263 - Alta Wind I, LLC; Alta Wind II, LLC; Alta Wind III, LLC; Alta Wind IV, LLC; Alta Wind V, LLC...

Science.gov (United States)

2010-05-03

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL10-62-000] Alta Wind I, LLC; Alta Wind II, LLC; Alta Wind III, LLC; Alta Wind IV, LLC; Alta Wind V, LLC; Alta Wind VI, LLC; Alta Wind VII, LLC; Alta Wind VIII, LLC; Alta Windpower Development, LLC; TGP Development Company, LLC...

Separation of Cr(III) from Cr(VI) by Triton X-100 Cerium (Iv) Phosphate as a Surface Active Ion Exchanger

International Nuclear Information System (INIS)

El-Azony, K.M.; Ismail Aydia, M.; El-Mohty, A.A.

2010-01-01

A new and simple high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection has been developed for the determination of both Cr (III) and Cr (VI) ions. Chromium species were determined by HPLC using a stationary phase consisting of a reversed phase column (Nucleosil phenyl column; 250 mm x 4.6 mm,5 μm), and a mobile phase consisting of a mixture of methanol: water(70 : 30 v/v), in which the complexing agent di-(2-ethylhexyl) phosphoric acid (DEHPA) was dissolved. The UV detection was carried out at wavelength 650 nm. Separation of Cr (III) from Cr (VI) on Triton X-100 cerium(IV) phosphate(TX-100 CeP) as a surface active ion exchanger was investigated. TX-100 CeP has been synthesized, characterized using IR, X-Ray, TGA/DTA and elemental analysis. The ion exchange capacity and chemical stability in different HCl concentration have been studied

Spectral analysis of the UFBG-based acousto—optical modulator in V-I transmission matrix formalism

Science.gov (United States)

Wu, Liang-Ying; Pei, Li; Liu, Chao; Wang, Yi-Qun; Weng, Si-Jun; Wang, Jian-Shuai

2014-11-01

In this study, the V-I transmission matrix formalism (V-I method) is proposed to analyze the spectrum characteristics of the uniform fiber Bragg grating (FBG)-based acousto—optic modulators (UFBG-AOM). The simulation results demonstrate that both the amplitude of the acoustically induced strain and the frequency of the acoustic wave (AW) have an effect on the spectrum. Additionally, the wavelength spacing between the primary reflectivity peak and the secondary reflectivity peak is proportional to the acoustic frequency with the ratio 0.1425 nm/MHz. Meanwhile, we compare the amount of calculation. For the FBG whose period is M, the calculation of the V-I method is 4 × (2M-1) in addition/subtraction, 8 × (2M - 1) in multiply/division and 2M in exponent arithmetic, which is almost a quarter of the multi-film method and transfer matrix (TM) method. The detailed analysis indicates that, compared with the conventional multi-film method and transfer matrix (TM) method, the V-I method is faster and less complex.

Activation of the CXCR3 chemokine receptor through anchoring of a small molecule chelator ligand between TM-III, -IV, and -VI

DEFF Research Database (Denmark)

Rosenkilde, Mette M; Andersen, Michael B; Nygaard, Rie

2006-01-01

modeling and molecular simulations combined with mutational analysis indicated that the metal ion site-anchored chelators act as agonists by establishing an aromatic-aromatic, second-site interaction with TyrVI:16 on the inner face of TM-VI. It is noteworthy that this interaction required......Seven transmembrane segment (7TM) receptors are activated through a common, still rather unclear molecular mechanism by a variety of chemical messengers ranging from monoamines to large proteins. By introducing a His residue at position III:05 in the CXCR3 receptor a metal ion site was built...... between the extracellular ends of transmembrane (TM) III and TM-IV to anchor aromatic chelators at a location corresponding to the presumed binding pocket for adrenergic receptor agonists. In this construct, free metal ions had no agonistic effect in accordance with the optimal geometry of the metal ion...

Characterization of Cr(VI) removal from aqueous solutions by a surplus agricultural waste-Rice straw

International Nuclear Information System (INIS)

Gao Hui; Liu Yunguo; Zeng Guangming; Xu Weihua; Li Ting; Xia Wenbin

2008-01-01

The removal of Cr(VI) from aqueous solution by rice straw, a surplus agricultural byproduct was investigated. The optimal pH was 2.0 and Cr(VI) removal rate increased with decreased Cr(VI) concentration and with increased temperature. Decrease in straw particle size led to an increase in Cr(VI) removal. Equilibrium was achieved in about 48 h under standard conditions, and Cr(III), which appeared in the solution and remained stable thereafter, indicating that both reduction and adsorption played a part in the Cr(VI) removal. The increase of the solution pH suggested that protons were needed for the Cr(VI) removal. A relatively high level of NO 3 - notably restrained the reduction of Cr(VI) to Cr(III), while high level of SO 4 2- supported it. The promotion of the tartaric acid modified rice straw (TARS) and the slight inhibition of the esterified rice straw (ERS) on Cr(VI) removal indicated that carboxyl groups present on the biomass played an important role in chromium remediation even though were not fully responsible for it. Isotherm tests showed that equilibrium sorption data were better represented by Langmuir model and the sorption capacity of rice straw was found to be 3.15 mg/g

Reduction of Cr (VI) into Cr (III) by organelles of Chlorella vulgaris in aqueous solution: An organelle-level attempt.

Science.gov (United States)

Chen, Zunwei; Song, Shufang; Wen, Yuezhong

2016-12-01

The priority pollutant chromium (Cr) was ubiquitous and great efforts have been made to reduce Cr (VI) into less-toxic Cr (III) by alga for the convenient availability and low expense. However, the functional role of organelle inside the algal cell in Cr (VI) reduction was poorly understood. In this study, organelles in green algae Chlorella vulgaris were extracted and further decorated for Cr (VI) reduction tests. Results showed that the chloroplast exhibited not only adsorption ability of total Cr (21.18% comparing to control) but also reduction potential of Cr (VI) (almost 70% comparing to control), whose most suitable working concentration was at 17μg/mL. Furtherly, the isolated thylakoid membrane (ITM) showed better Cr (VI) reduction potential with the presence of sodium alginate (SA), even though the Hill reaction activity (HRA) was inhibited. As for photosystem II (PSII), the addition of mesoporous silica SBA-15 enhanced the reduction ability through improving the light-harvesting complex (LHC) II efficiency and electron transport rate. On the whole, the reduction ability order of the three kinds of materials based on chloroplast in C. vulgaris was PSII@SBA-15>Chloroplast>ITM@SA. The attempt made in this study to reduce the Cr (VI) with C. vulgaris organelles might not only offer basement to detect the potential action mechanism of Cr (VI) reduction by C. vulgaris but also provide a new sight for the scavenge of heavy metal with biological materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Monophasic Pulsed 200-μA Current Promotes Galvanotaxis With Polarization of Actin Filament and Integrin α2β1 in Human Dermal Fibroblasts.

Science.gov (United States)

Uemura, Mikiko; Maeshige, Noriaki; Koga, Yuka; Ishikawa-Aoyama, Michiko; Miyoshi, Makoto; Sugimoto, Masaharu; Terashi, Hiroto; Usami, Makoto

2016-01-01

The monophasic pulsed microcurrent is used to promote wound healing, and galvanotaxis regulation has been reported as one of the active mechanisms in the promotion of tissue repair with monophasic pulsed microcurrent. However, the optimum monophasic pulsed microcurrent parameters and intracellular changes caused by the monophasic pulsed microcurrent have not been elucidated in human dermal fibroblasts. The purpose of this study was to investigate the optimum intensity for promoting galvanotaxis and the effects of electrical stimulation on integrin α2β1 and actin filaments in human dermal fibroblasts. Human dermal fibroblasts were treated with the monophasic pulsed microcurrent of 0, 100, 200, or 300 μA for 8 hours, and cell migration and cell viability were measured 24 hours after starting monophasic pulsed microcurrent stimulation. Polarization of integrin α2β1 and lamellipodia formation were detected by immunofluorescent staining 10 minutes after starting monophasic pulsed microcurrent stimulation. The migration toward the cathode was significantly higher in the cells treated with the 200-μA monophasic pulsed microcurrent than in the controls (P microcurrent did not alter the migration ratio. The electrostimulus of 200 μA also promoted integrin α2β1 polarization and lamellipodia formation at the cathode edge (P microcurrent intensity to promote migration toward the cathode, and this intensity could regulate polarization of migration-related intracellular factors in human dermal fibroblasts.

Dynamics of intraocular IFN-γ, IL-17 and IL-10-producing cell populations during relapsing and monophasic rat experimental autoimmune uveitis.

Directory of Open Access Journals (Sweden)

Ulrike Kaufmann

Full Text Available A major limitation of most animal models of autoimmune diseases is that they do not reproduce the chronic or relapsing-remitting pattern characteristic of many human autoimmune diseases. This problem has been overcome in our rat models of experimentally induced monophasic or relapsing-remitting autoimmune uveitis (EAU, which depend on the inducing antigen peptides from retinal S-Antigen (monophasic EAU or interphotoreceptor retinoid-binding protein (relapsing EAU. These models enable us to compare autoreactive and regulatory T cell populations. Intraocular, but not peripheral T cells differ in their cytokine profiles (IFN-γ, IL-17 and IL-10 at distinct time points during monophasic or relapsing EAU. Only intraocular T cells concomitantly produced IFN-γ, IL-17 and/or IL-10. Monophasic EAU presented rising numbers of cells expressing IFN-γ and IL-17 (Th1/Th17 and cells expressing IL-10 or Foxp3. During relapsing uveitis an increase of intraocular IFN-γ+ cells and a concomitant decrease of IL-17+ cells was detected, while IL-10+ populations remained stable. Foxp3+ cells and cells expressing IL-10, even in combination with IFN-γ or IL-17, increased during the resolution of monophasic EAU, suggesting a regulatory role for these T cells. In general, cells producing multiple cytokines increased in monophasic and decreased in relapsing EAU. The distinct appearance of certain intraocular populations with characteristics of regulatory cells points to a differential influence of the ocular environment on T cells that induce acute and monophasic or relapsing disease. Here we provide evidence that different autoantigens can elicit distinct and differently regulated immune responses. IFN-γ, but not IL-17 seems to be the key player in relapsing-remitting uveitis, as shown by increased, synchronized relapses after intraocular application of IFN-γ. We demonstrated dynamic changes of the cytokine pattern during monophasic and relapsing-remitting disease

Stellar laboratories . IX. New Se v, Sr iv-vii, Te vi, and I vi oscillator strengths and the Se, Sr, Te, and I abundances in the hot white dwarfs G191-B2B and RE 0503-289

Science.gov (United States)

Rauch, T.; Quinet, P.; Knörzer, M.; Hoyer, D.; Werner, K.; Kruk, J. W.; Demleitner, M.

2017-10-01

Context. To analyze spectra of hot stars, advanced non-local thermodynamic equilibrium (NLTE) model-atmosphere techniques are mandatory. Reliable atomic data is crucial for the calculation of such model atmospheres. Aims: We aim to calculate new Sr iv-vii oscillator strengths to identify for the first time Sr spectral lines in hot white dwarf (WD) stars and to determine the photospheric Sr abundances. To measure the abundances of Se, Te, and I in hot WDs, we aim to compute new Se v, Te vi, and I vi oscillator strengths. Methods: To consider radiative and collisional bound-bound transitions of Se v, Sr iv - vii, Te vi, and I vi in our NLTE atmosphere models, we calculated oscillator strengths for these ions. Results: We newly identified four Se v, 23 Sr v, 1 Te vi, and three I vi lines in the ultraviolet (UV) spectrum of RE 0503-289. We measured a photospheric Sr abundance of 6.5+ 3.8-2.4× 10-4 (mass fraction, 9500-23 800 times solar). We determined the abundances of Se (1.6+ 0.9-0.6× 10-3, 8000-20 000), Te (2.5+ 1.5-0.9× 10-4, 11 000-28 000), and I (1.4+ 0.8-0.5× 10-5, 2700-6700). No Se, Sr, Te, and I line was found in the UV spectra of G191-B2B and we could determine only upper abundance limits of approximately 100 times solar. Conclusions: All identified Se v, Sr v, Te vi, and I vi lines in the UV spectrum of RE 0503-289 were simultaneously well reproduced with our newly calculated oscillator strengths. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. Full Tables A.15 to A.21 are only available via the German Astrophysical Virtual Observatory (GAVO) service TOSS (http://dc.g-vo.org/TOSS).

III-nitrides, 2D transition metal dichalcogenides, and their heterojunctions

KAUST Repository

Mishra, Pawan

2017-01-01

Group III-nitride materials have attracted great attention for applications in high efficiency electronic and optoelectronics devices such as high electron mobility transistors, light emitting diodes, and laser diodes. On the other hand, group VI

Intervening O vi Quasar Absorption Systems at Low Redshift: A Significant Baryon Reservoir.

Science.gov (United States)

Tripp; Savage; Jenkins

2000-05-01

Far-UV echelle spectroscopy of the radio-quiet QSO H1821+643 (zem=0.297), obtained with the Space Telescope Imaging Spectrograph (STIS) at approximately 7 km s-1 resolution, reveals four definite O vi absorption-line systems and one probable O vi absorber at 0.15quasar in redshift; these are likely intervening systems unrelated to the background QSO. In the case of the strong O vi system at zabs=0.22497, multiple components are detected in Si iii and O vi as well as H i Lyman series lines, and the differing component velocity centroids and b-values firmly establish that this is a multiphase absorption system. A weak O vi absorber is detected at zabs=0.22637, i.e., offset by approximately 340 km s-1 from the zabs=0.22497 system. Lyalpha absorption is detected at zabs=0.22613, but no Lyalpha absorption is significantly detected at 0.22637. Other weak O vi absorbers at zabs=0.24531 and 0.26659 and the probable O vi system at 0.21326 have widely diverse O vi/H i column density ratios with N(O vi)/N(H i) ranging from vi absorbers with rest equivalent width greater than 30 mÅ in the H1821+643 spectrum is remarkably high, dN&solm0;dz approximately 48, which implies with a high (90%) confidence that it is greater than 17 in the low-redshift intergalactic medium. We conservatively estimate that the cosmological mass density of the O vi systems is Omegab(Ovi&parr0; greater, similar0.0008 h-175. With an assumed metallicity of 1/10 solar and a conservative assumption that the fraction of oxygen in the O vi ionization stage is 0.2, we obtain Omegab(Ovi&parr0; greater, similar0.004 h-175. This is comparable to the combined cosmological mass density of stars and cool gas in galaxies and X-ray-emitting gas in galaxy clusters at low redshift.

Importance of c-Type cytochromes for U(VI reduction by Geobacter sulfurreducens

Directory of Open Access Journals (Sweden)

Leang Ching

2007-03-01

Full Text Available Abstract Background In order to study the mechanism of U(VI reduction, the effect of deleting c-type cytochrome genes on the capacity of Geobacter sulfurreducens to reduce U(VI with acetate serving as the electron donor was investigated. Results The ability of several c-type cytochrome deficient mutants to reduce U(VI was lower than that of the wild type strain. Elimination of two confirmed outer membrane cytochromes and two putative outer membrane cytochromes significantly decreased (ca. 50–60% the ability of G. sulfurreducens to reduce U(VI. Involvement in U(VI reduction did not appear to be a general property of outer membrane cytochromes, as elimination of two other confirmed outer membrane cytochromes, OmcB and OmcC, had very little impact on U(VI reduction. Among the periplasmic cytochromes, only MacA, proposed to transfer electrons from the inner membrane to the periplasm, appeared to play a significant role in U(VI reduction. A subpopulation of both wild type and U(VI reduction-impaired cells, 24–30%, accumulated amorphous uranium in the periplasm. Comparison of uranium-accumulating cells demonstrated a similar amount of periplasmic uranium accumulation in U(VI reduction-impaired and wild type G. sulfurreducens. Assessment of the ability of the various suspensions to reduce Fe(III revealed no correlation between the impact of cytochrome deletion on U(VI reduction and reduction of Fe(III hydroxide and chelated Fe(III. Conclusion This study indicates that c-type cytochromes are involved in U(VI reduction by Geobacter sulfurreducens. The data provide new evidence for extracellular uranium reduction by G. sulfurreducens but do not rule out the possibility of periplasmic uranium reduction. Occurrence of U(VI reduction at the cell surface is supported by the significant impact of elimination of outer membrane cytochromes on U(VI reduction and the lack of correlation between periplasmic uranium accumulation and the capacity for uranium

Cr(VI) adsorption from electroplating plating wastewater by chemically modified coir pith.

Science.gov (United States)

Suksabye, Parinda; Thiravetyan, Paitip

2012-07-15

Coir pith samples were chemically modified by grafting with acrylic acid for the removal of Cr(VI) from electroplating wastewater. The presence of acrylic acid on the coir pith surface was verified by a scanning electron microscope with an electron dispersive x-ray spectrometer (SEM/EDX), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). The carbonyl groups (C==O) from the carboxylic acids (COOH) increased on the coir pith surface after grafting with acrylic acid. In addition, the thermal stability of the acrylic acid-grafted coir pith also improved. The optimum conditions for grafting the acrylic acid on the coir pith consisted of 2 M acrylic acid and 0.00125 M ceric ammonium nitrate (CAN, as an initiator). The maximum Cr(VI) removal (99.99 ± 0.07%) was obtained with the following conditions: a 1.3% (w/v) dosage of acrylic acid-grafted coir pith, a system pH of 2, a contact time of 22 h, a temperature of 30 °C, a particle size of <150 μm and an initial Cr(VI) of 1,171 mg l(-1). At system pH of 2, Cr(VI) in the HCrO(4)(-) form can be adsorbed with acrylic acid-grafted coir pith via an electrostatic attraction. The adsorption isotherm of 2 M acrylic acid-grafted coir pith exhibited a good fit with the Langmuir isotherm. The maximum Cr(VI) adsorption capacity of the 2 M acrylic acid-grafted coir pith was 196.00 mg Cr(VI) g(-1) adsorbent, whereas for coir pith without grafting, the maximum Cr(VI) removal was 165.00 mg Cr(VI) g(-1) adsorbent. The adsorption capacity of the acrylic acid-grafted coir pith for Cr(VI) was higher compared to the original coir pith. This result was due to the enhancement of the carbonyl groups on the coir pith surface that may have involved the mechanism of chromium adsorption. The X-ray absorption near edged structure (XANES) and desorption studies suggested that most of the Cr(III) that presented on the acrylic acid-grafted coir pith was due to the Cr(VI) being reduced to Cr(III) on the adsorbent surface. FTIR

Analytical use of zide ion. Chemical equilibrium studies and correlates in U(VI)/N3 and Co(III)/N3 systems

International Nuclear Information System (INIS)

Silva, T.V. da.

1984-01-01

A monographic study about the azide ion and its structure, as well as, references about the uranyl ion in aqueous medium, and its possible hydrolysis products are shown. Spectral studies of the U(VI), Fe (III) and Cu(II) systems, in azide medium are analyzed. (M.J.C.) [pt

Study of Cr(VI) adsorption onto magnetite nanoparticles using synchrotron-based X-ray absorption spectroscopy

Science.gov (United States)

Chen, Yen-Hua; Liu, Dian-Yu; Lee, Jyh-Fu

2018-04-01

In this study, the efficiency of Cr(VI) adsorption onto nano-magnetite was examined by batch experiments, and the Cr(VI) adsorption mechanism was investigated using synchrotron-based X-ray absorption spectroscopy. Magnetite nanoparticles with a mean diameter of 10 nm were synthesized using an inexpensive and simple co-precipitation method. It shows a saturation magnetization of 54.3 emu/g, which can be recovered with an external magnetic field. The adsorption data fitted the Langmuir adsorption isotherm well, implying a monolayer adsorption behavior of Cr(VI) onto nano-magnetite. X-ray absorption spectroscopy results indicate that the adsorption mechanism involves electron transfer between Fe(II) in nano-magnetite (Fe2+OFe3+ 2O3) and Cr(VI) to transform into Cr(III), which may exist as an Fe(III)-Cr(III) mixed solid phase. Moreover, the Cr(III)/Cr(VI) ratio in the final products can be determined by the characteristic pre-edge peak area of Cr(VI) in the Cr K-edge spectrum. These findings suggest that nano-magnetite is effective for Cr(VI) removal from wastewater because it can transform highly poisonous Cr(VI) species into nontoxic Cr(III) compounds, which are highly insoluble and immobile under environmental conditions.

Explorations of new phases in the Ga(III)/In(III)-Mo(VI)-Se(IV)/Te(IV)-O systems.

Science.gov (United States)

Kong, Fang; Hu, Chun-Li; Hu, Ting; Zhou, Yong; Mao, Jiang-Gao

2009-07-07

Systematic explorations of new phases in the Ga(III)/In(III)-Mo(VI)-Se(IV)/Te(IV)-O systems by hydrothermal syntheses or solid-state reactions at high-temperature led to four new quaternary compounds, namely, Ga(2)MoQ(2)O(10) (Q = Se, Te), In(2)Mo(2)Se(2)O(13)(H(2)O) and In(2)MoTe(2)O(10). Ga(2)MoQ(2)O(10) (Q = Se, Te) are isostructural and their structures feature a 3D network of gallium selenite/tellurite with 12-member ring tunnels along b-axis, the distorted MoO(6) octahedra are attached on the wall of the above tunnels. The structure of In(2)Mo(2)Se(2)O(13)(H(2)O) features a new pillared-layered architecture composed of 2D indium(III) selenite layers that are interconnected by Mo(2)O(10) dimers, forming 8-membered ring tunnels along the b-axis. The structure of In(2)MoTe(2)O(10) features a 2D indium oxide layer formed by corner- and edge-sharing InO(6) and InO(7) polyhedra with MoO(4) tetrahedra and TeO(n) (n = 4, 5) polyhedra hanging on both sides of the layer, there are weak interlayer Te-O bonds of 2.512 A. Results of optical diffuse reflectance spectrum measurements indicate that all four compounds are insulators, which are in agreement with results of band structure calculations based on DFT methods.

A new turn-on fluorimetric method for the rapid speciation of Cr(III)/Cr(VI) species in tea samples with rhodamine-based fluorescent reagent

Science.gov (United States)

Özyol, Esra; Saçmacı, Şerife; Saçmacı, Mustafa; Ülgen, Ahmet

2018-02-01

A new fluorimetric method with rhodamine-based fluorescent agent was developed for the rapid speciation of Cr(III)/Cr(VI) in tea, soil and water samples. The system, which utilizes a fluorescent reagent, was used for the first time after synthesis/characterization of 3‧,6‧-bis(diethylamino)-2-{[(1E)-(2,4-dimethoxyphenyl)methylene] amino}spiro[isoindole-1,9‧-xanthen]-3(2H)-one (BDAS). The reagent responds instantaneously at room temperature in a 1:1 stoichiometric manner to the amount of Cr(III). The selectivity of this system for Cr(III) over other metal ions is remarkably high, and its sensitivity is below 0.01 mg L- 1 in aqueous solutions which enables a simplification without any pretreatment of the real sample. The method has a wide linear range of 0.1-10 mg L- 1 and a detection limit of 0.15 μg L- 1 for Cr(III) while the relative standard deviation was 0.1% for 0.1 mg L- 1 Cr(III) concentration. The results of detection and recovery experiments for Cr(III) in tea, soil and water were satisfactory, indicating that the method has better feasibility and application potential in the routine determination and speciation of Cr(III)/Cr(VI). The results of analysis of the certified reference material (INCT-TL-1 tea sample and CWW-TM-D waste water) are in good agreement with the certified value.

K4Nb6O17·4.5H2O: A novel dual functional material with quick photoreduction of Cr(VI) and high adsorptive capacity of Cr(III)

International Nuclear Information System (INIS)

Ma, Yuli; Liu, Xiaoqing; Li, Yang; Su, Yiguo; Chai, Zhanli; Wang, Xiaojing

2014-01-01

Graphical abstract: A well crystalline K 4 Nb 6 O 17 ·4.5H 2 O with a wide layer spacing possesses an excellent disposal performance for chromium species of Cr(VI) and Cr(III) as well as the superior recyclability due to its high stability and convenient regeneration process. - Highlights: • A nano-sheet K 4 Nb 6 O 17 ·4.5H 2 O with a large layer spacing was synthesized. • K 4 Nb 6 O 17 ·4.5H 2 O showed a superior photoreduction of Cr(VI) in an acidic solution. • The sample showed a high adsorption capacity of Cr(III) in a near neutral solution. • K 4 Nb 6 O 17 ·4.5H 2 O regenerated conveniently by immersing in a KOH solution. • A complete removal of chromium species was retained after recycling five times. - Abstract: A series of orthorhombic phase K 4 Nb 6 O 17 ·4.5H 2 O was synthesized via a hydrothermal approach. When presented in an acidic pH range, K 4 Nb 6 O 17 ·4.5H 2 O showed a strong ability in quick reduction from Cr(VI) to Cr(III). The resulted Cr(III) ions were removed by an effective adsorption through simply adjusting the solution pH from strong acidity to near neutrality, owing to the sample's unique nano-sheet structure with a wide layer spacing. The Cr(III) ions adsorbed onto samples were released again for reusing by eluting with 1 mol L −1 HCl solution, and K 4 Nb 6 O 17 ·4.5H 2 O regenerated by immersing in a KOH solution. The reduction efficiency of Cr(VI) was still up to 98% after irradiation for 60 min, and the removal efficiency of Cr(III) ions was as high as 83% even after five cycles. Therefore, K 4 Nb 6 O 17 ·4.5H 2 O is clearly demonstrated to be an excellent dual functional material with quick photoreduction of Cr(VI) and high adsorptive capacity of Cr(III). The relevant materials reported herein might be found various environment-related applications

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

OpenAIRE

Sugiyama, M

1994-01-01

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

Microbial reduction of uranium(VI) in sediments of different lithologies collected from Sellafield

International Nuclear Information System (INIS)

Newsome, Laura; Morris, Katherine; Trivedi, Divyesh; Atherton, Nick; Lloyd, Jonathan R.

2014-01-01

Highlights: • U(VI) (aq) mobility can be controlled by stimulating biogeochemical interactions. • Indigenous microbes in varied sediments reduced U(VI) to insoluble U(IV). • Sediment cell numbers and amount of bioavailable Fe(III) could limit this process. - Abstract: The presence of uranium in groundwater at nuclear sites can be controlled by microbial processes. Here we describe the results from stimulating microbial reduction of U(VI) in sediment samples obtained from a nuclear-licensed site in the UK. A variety of different lithology sediments were selected to represent the heterogeneity of the subsurface at a site underlain by glacial outwash deposits and sandstone. The natural sediment microbial communities were stimulated via the addition of an acetate/lactate electron donor mix and were monitored for changes in geochemistry and molecular ecology. Most sediments facilitated the removal of 12 ppm U(VI) during the onset of Fe(III)-reducing conditions; this was reflected by an increase in the proportion of known Fe(III)- and U(VI)-reducing species. However U(VI) remained in solution in two sediments and Fe(III)-reducing conditions did not develop. Sequential extractions, addition of an Fe(III)-enrichment culture and most probable number enumerations revealed that a lack of bioavailable iron or low cell numbers of Fe(III)-reducing bacteria may be responsible. These results highlight the potential for stimulation of microbial U(VI)-reduction to be used as a bioremediation strategy at UK nuclear sites, and they emphasise the importance of both site-specific and borehole-specific investigations to be completed prior to implementation

Syntheses of polystyrene supported chelating resin containing the Schiff base derived from salicylaldehyde and triethylene tetramine and its copper(II), nickel(II), cobalt(II), iron(III), zinc(II), cadmium(II), molybdenum(VI), zirconium(IV) and uranium(VI) complexes

International Nuclear Information System (INIS)

Syamal, A.; Singh, M.M.

1998-01-01

A new polymer-anchored chelating ligand has been synthesized by the reaction of chloromethylated polystyrene (containing 0.94 mmol of Cl per gram of resin and 1% cross-linked with divinylbenzene) and the Schiff base derived from salicylaldehyde and triethylenetetramine. A new series of polystyrene supported, Cu(II), Ni(II), Co(II), Fe(III), Zn(II), Cd(II), Zr(IV), dioxomolybdenum (VI) and dioxouranium (VI) complexes of the formulae PS-LCu, PS-LNi, PS-LCo, PS-LFeCl.DMF, PS-LZn, PS-LCd, PS-LZr(OH) 2 . DMF, PS L MoO 2 and PS-LUO 2 (where PS-LH 2 = polymer-anchored Schiff base and DMF dimethyl-formamide) have been synthesized and characterised by elemental analysis, infrared, electronic spectra and magnetic susceptibility measurements. The complexes PS-LCu, PS-LNi and PS-LCo have square planar structure, PS-LFeCl.DMF, PS-LMoO 2 and PS-LUO 2 have octahedral structure, PS L Zn and PS-LCd are tetrahedral and PS-LZr(OH) 2 .DMF is pentagonal bipyramidal. The polymer-anchored Cu(II), Co(II) and Fe(III) complexes are paramagnetic while Ni(II), Zn(II), Cd(II), Zr(IV), dioxomolybdenum(VI) and dioxouranium(VI) complexes are diamagnetic. The negative shift of the v (C=N) (azomethine) and the positive shift of v (C--O)(phenolic) are indicative of ONNO donor behaviour of the polymer-anchored Schiff base. (author)

Analytical Electron Diffraction from Iii-V and II-Vi Semiconductors

Science.gov (United States)

Spellward, Paul

Available from UMI in association with The British Library. This thesis describes the development and evaluation of a number of new TEM-based techniques for the measurement of composition in ternary III-V and II-VI semiconductors. New methods of polarity determination in binary and ternary compounds are also presented. The theory of high energy electron diffraction is outlined, with particular emphasis on zone axis diffraction from well-defined strings. An account of TEM microstructural studies of Cd_{rm x}Hg _{rm 1-x}Te and CdTe epitaxial layers, which provided the impetus for developing the diffraction-based analytical techniques, is given. The wide range of TEM-based compositional determination techniques is described. The use of HOLZ deficiency lines to infer composition from a lattice parameter measurement is evaluated. In the case of Cd_{ rm x}Hg_{rm 1-x}Te, it is found to be inferior to other techniques developed. Studies of dynamical aspects of HOLZ diffraction can yield information about the dispersion surface from which a measure of composition may be obtained. This technique is evaluated for Al_{rm x}Ga_{rm 1-x} As, in which it is found to be of some use, and for Cd_{rm x}Hg _{rm 1-x}Te, in which the large Debye-Waller factor associated with mercury in discovered to render the method of little value. A number of critical voltages may be measured in medium voltage TEMs. The (111) zone axis critical voltage of Cd_{rm x}Hg _{rm 1-x}Te is found to vary significantly with x and forms the basis of an accurate technique for composition measurement in that ternary compound. Other critical voltage phenomena are investigated. In Al _{rm x}Ga_ {rm 1-x}As and other light ternaries, a non-systematic critical voltage is found to vary with x, providing a good indicator of composition. Critical voltage measurements may be made by conventional CBED or by various other techniques, which may also simultaneously yield information on the spatial variation of composition. The

Characterization of a ViI-like Phage Specific to Escherichia coli O157:H7

Directory of Open Access Journals (Sweden)

Kropinski Andrew M

2011-09-01

Full Text Available Abstract Phage vB_EcoM_CBA120 (CBA120, isolated against Escherichia coli O157:H7 from a cattle feedlot, is morphologically very similar to the classic phage ViI of Salmonella enterica serovar Typhi. Until recently, little was known genetically or physiologically about the ViI-like phages, and none targeting E. coli have been described in the literature. The genome of CBA120 has been fully sequenced and is highly similar to those of both ViI and the Shigella phage AG3. The core set of structural and replication-related proteins of CBA120 are homologous to those from T-even phages, but generally are more closely related to those from T4-like phages of Vibrio, Aeromonas and cyanobacteria than those of the Enterobacteriaceae. The baseplate and method of adhesion to the host are, however, very different from those of either T4 or the cyanophages. None of the outer baseplate proteins are conserved. Instead of T4's long and short tail fibers, CBA120, like ViI, encodes tail spikes related to those normally seen on podoviruses. The 158 kb genome, like that of T4, is circularly permuted and terminally redundant, but unlike T4 CBA120 does not substitute hmdCyt for cytosine in its DNA. However, in contrast to other coliphages, CBA120 and related coliphages we have isolated cannot incorporate 3H-thymidine (3H-dThd into their DNA. Protein sequence comparisons cluster the putative "thymidylate synthase" of CBA120, ViI and AG3 much more closely with those of Delftia phage φW-14, Bacillus subtilis phage SPO1, and Pseudomonas phage YuA, all known to produce and incorporate hydroxymethyluracil (hmdUra.

Duration of the pubertal peak in skeletal Class I and Class III subjects.

Science.gov (United States)

Kuc-Michalska, Małgorzata; Baccetti, Tiziano

2010-01-01

To estimate and compare the duration of the pubertal growth peak in Class I and Class III subjects. The data examined consisted of pretreatment lateral cephalometric records of 218 skeletal Class I or Class III subjects (93 female and 125 male subjects) of white ancestry. The duration of the pubertal peak was calculated from the average chronological age intervals between stages CS3 and CS4 of the cervical vertebral maturation in Class I vs Class III groups (t-test). In skeletal Class I subjects, the pubertal peak had a mean duration of 11 months, whereas in Class III subjects it lasted 16 months. The average difference (5 months) was statistically significant (P < .001). The growth interval corresponding to the pubertal growth spurt (CS3-CS4) was longer in Class III subjects than in subjects with normal skeletal relationships; the larger increases in mandibular length during the pubertal peak reported in the literature for Class III subjects may be related to the longer duration of the pubertal peak.

Vi har intet lært - hvornår lærer vi det?

DEFF Research Database (Denmark)

Sodemann, Morten

2016-01-01

WHO anså fra i går ikke længere ebola for at være en trussel mod global folkesundhed, så fra i dag er kameraerne slukket i Vestafrika og vi er tilbage hvor vi startede. SDG målene skal have et dansk udtryk, men hvad er de danske kompetencer på globalt plan når sundhed ikke længere er en kerneakti......WHO anså fra i går ikke længere ebola for at være en trussel mod global folkesundhed, så fra i dag er kameraerne slukket i Vestafrika og vi er tilbage hvor vi startede. SDG målene skal have et dansk udtryk, men hvad er de danske kompetencer på globalt plan når sundhed ikke længere er en...

Modelling Cr(VI) removal by a combined carbon-activated sludge system

International Nuclear Information System (INIS)

Orozco, A. Micaela Ferro; Contreras, Edgardo M.; Zaritzky, Noemi E.

2008-01-01

The combined carbon-activated sludge process has been proposed as an alternative to protect the biomass against toxic substances in wastewaters; however, the information about the effect of powdered-activated carbon (PAC) addition in activated sludge reactors for the treatment of wastewaters containing Cr(VI) is limited. The objectives of the present study were: (a) to evaluate the removal of hexavalent chromium by (i) activated sludge microorganisms in aerobic batch reactors, (ii) powdered-activated carbon, and (iii) the combined action of powdered-activated carbon and biomass; (b) to propose mathematical models that interpret the experimental results. Different Cr(VI) removal systems were tested: (S1) biomass (activated sludge), (S2) PAC, and (S3) the combined activated carbon-biomass system. A Monod-based mathematical model was used to describe the kinetics of Cr(VI) removal in the system S1. A first-order kinetics with respect to Cr(VI) and PAC respectively, was proposed to model the removal of Cr(VI) in the system S2. Cr(VI) removal in the combined carbon-biomass system (S3) was faster than both Cr(VI) removal using PAC or activated sludge individually. Results showed that the removal of Cr(VI) using the activated carbon-biomass system (S3) was adequately described by combining the kinetic equations proposed for the systems S1 and S2

78 FR 32462 - Wyatt Virgin Islands (V.I.), Inc., a Division of Wyatt Field Service Company, Working On-Site at...

Science.gov (United States)

2013-05-30

... the subject worker group was established to exclusively work at the HOVENSA refinery plant in the U.S....), Inc., a Division of Wyatt Field Service Company, Working On-Site at Hovensa, LLC Oil Refinery... (V.I.), Inc., a division of Wyatt Field Service Company, working on-site at HOVENSA, LLC Oil Refinery...

33 CFR 110.250 - St. Thomas Harbor, Charlotte Amalie, V.I.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false St. Thomas Harbor, Charlotte... SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.250 St. Thomas Harbor, Charlotte Amalie.... Thomas, V.I. of the United States and approaches thereto, including all waters under its jurisdiction, as...

Statistical Analysis of Langmuir Waves Associated with Type III Radio Bursts: I. Wind Observations

Directory of Open Access Journals (Sweden)

Vidojević S.

2011-12-01

Full Text Available Interplanetary electron beams are unstable in the solar wind and they generate Langmuir waves at the local plasma frequency or its harmonic. Radio observations of the waves in the range 4-256 kHz, observed in 1994-2010 with the WAVES experiment onboard the WIND spacecraft, are statistically analyzed. A subset of 36 events with Langmuir waves and type III bursts occurring at the same time was selected. After removal of the background, the remaining power spectral density is modeled by the Pearson system of probability distributions (types I, IV and VI. The Stochastic Growth Theory (SGT predicts log-normal distribution for the power spectrum density of the Langmuir waves. Our results indicate that SGT possibly requires further verification.

Weak antilocalization induced by Rashba spin-orbit interaction in layered III-VI compound semiconductor GaSe thin films

Science.gov (United States)

Takasuna, Shoichi; Shiogai, Junichi; Matsuzaka, Shunichiro; Kohda, Makoto; Oyama, Yutaka; Nitta, Junsaku

2017-10-01

Magnetoconductance (MC) at low temperature was measured to investigate spin-related transport affected by spin-orbit interaction (SOI) in III-VI compound n -type GaSe thin films. Results reveal that MC shows weak antilocalization (WAL). Its temperature and gate voltage dependences reveal that the dominant spin relaxation is governed by the D'yakonov-Perel' mechanism associated with the Rashba SOI. The estimated Rashba SOI strength in GaSe is much stronger than that of III-V compound GaAs quantum wells, although the energy gap and spin split-off band in GaSe closely resemble those in GaAs. The angle dependence of WAL amplitude in the in-plane magnetic field direction is almost isotropic. This isotropy indicates that the strength of the Dresselhaus SOI is negligible compared with the Rashba SOI strength. The SOI effect in n -GaSe thin films differs greatly from those of III-V compound semiconductors and transition-metal dichalcogenides.

CaCO3-III and CaCO3-VI, high-pressure polymorphs of calcite: Possible host structures for carbon in the Earth's mantle

Science.gov (United States)

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

A simple Cr(VI)–S(IV)–O{sub 2} system for rapid and simultaneous reduction of Cr(VI) and oxidative degradation of organic pollutants

Energy Technology Data Exchange (ETDEWEB)

Yuan, Yanan; Yang, Shaojie [Department of Environmental Science, Hubei Key Lab of Biomass Resource Chemistry and Environmental Biotechnology, School of Resources and Environmental Science, Wuhan University, 430079 (China); Zhou, Danna, E-mail: zdncug@163.com [Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Wu, Feng [Department of Environmental Science, Hubei Key Lab of Biomass Resource Chemistry and Environmental Biotechnology, School of Resources and Environmental Science, Wuhan University, 430079 (China)

2016-04-15

Highlights: • Rapid and simultaneous reduction of Cr(VI) and degradation of organic pollutants occur. • Oxysulfur radicals generated in Cr(VI)–S(IV)–O{sub 2} system oxidize the organic pollutants. • Acidic pH facilitates the reactions from both directions of reduction and oxidation. • Degradation potential of aromatic amines depends on the substituted groups. • Cr(VI)–S(IV)–O{sub 2} system is promising for “waste control by waste”. - Abstract: Hexavalent chromium (Cr(VI)), a heavy-metal contaminant, can be easily reduced to less toxic trivalent chromium (Cr(III)) by sulfite ions (S(IV)). However, S(IV) has not drawn as much attention as the ferrous ion has. We report herein a novel Cr(VI)–S(IV)–O{sub 2} system containing sulfite ions that rapidly and simultaneously reduces Cr(VI) and oxidize organic pollutants in the presence of oxygen in aqueous solutions. This Cr(VI)–S(IV)-O{sub 2} system contains the initiator Cr(VI), the reductant S(IV), and the oxidant O{sub 2}, which produce oxysulfur radicals (mainly SO{sub 4}·{sup −} and SO{sub 5}·{sup −}) and hydroxyl radicals (OH·). The Cr(VI)/S(IV) molar ratio, pH, and oxygen content play important roles in the entire reaction system. Acidic conditions (pH 3.0) facilitated degradation of organic compounds and reduction of Cr(VI) as well. In addition, experiments of rapid degradation of several kinds of organic pollutants such as azo dye (acid orange 7, AO7), aniline, phenol, bisphenol A etc were also conducted. Preliminary results show that the removal rates of the analogs of phenols or aromatic amines in this Cr(VI)–S(IV)–O{sub 2} system have a relationship with the electronic parameters (Hammett constant, σ) of the substituted groups. Thus, the Cr(VI)–S(IV)–O{sub 2} system, provides an excellent strategy of “waste control by waste” for removing multiple industrial contaminants.

catena-Poly[[tetrakis(hexamethylphosphoramide-κObis(nitrato-κ2O,O′lanthanum(III] [silver(I-di-μ2-sulfido-tungstate(VI-di-μ2-sulfido

Directory of Open Access Journals (Sweden)

Lude Lu

2008-02-01

Full Text Available Hexamethylphosphoramide (hmp, tetrathiotungstate(VI, silver sulfide and lanthanum(III nitrate are self-assembled to form discrete cations one-dimensional poylmeric anionic chains [AgWS4]nn− in the title compound, {[La(NO32(C6H18N3OP4][AgWS4]}n. The central La atom in the cation is coordinated by eight O atoms from two nitrate and four hmp ligands. Together with the two nitrate ligands, the cation is monovalent, which leads to the anionic chain having a monovalent repeat unit. The polymeric anionic chain with W...Ag...W and Ag...W...Ag angles of 165.94 (3 and 155.894 (14° presents a distorted linear configuration. Five N atoms, 18 C atoms and their attached H atoms are disordered equally over two positions.

Impact of the uranium (VI) speciation in mineralised urines on its extraction by calix[6]arene bearing hydroxamic groups used in chromatography columns.

Science.gov (United States)

Baghdadi, S; Bouvier-Capely, C; Ritt, A; Peroux, A; Fevrier, L; Rebiere, F; Agarande, M; Cote, G

2015-11-01

Actinides determination in urine samples is part of the analyses performed to monitor internal contamination in case of an accident or a terrorist attack involving nuclear matter. Mineralisation is the first step of any of these analyses. It aims at reducing the sample volume and at destroying all organic compounds present. The mineralisation protocol is usually based on a wet ashing step, followed by actinides co-precipitation and a furnace ashing step, before redissolution and the quantification of the actinides by the appropriate techniques. Amongst the existing methods to perform the actinides co-precipitation, alkali-earth (typically calcium) precipitation is widely used. In the present work, the extraction of uranium(VI), plutonium(IV) and americium(III) from the redissolution solutions (called "mineralised urines") on calix[6]arene columns bearing hydroxamic groups was investigated as such an extraction is a necessary step before their determination by ICP-MS or alpha spectrometry. Difficulties were encountered in the transfer of uranium(VI) from raw to mineralised urines, with yield of transfer ranging between 0% and 85%, compared to about 90% for Pu and Am, depending on the starting raw urines. To understand the origin of such a difficulty, the speciation of uranium (VI) in mineralised urines was investigated by computer simulation using the MEDUSA software and the associated HYDRA database, compiled with recently published data. These calculations showed that the presence of phosphates in the "mineralised urines" leads to the formation of strong uranyl-phosphate complexes (such as UO2HPO4) which compete with the uranium (VI) extraction by the calix[6]arene bearing hydroxamic groups. The extraction constant of uranium (VI) by calix[6]arene bearing hydroxamic groups was determined in a 0.04 mol L(-1) sodium nitrate solution (logK=4.86±0.03) and implemented in an extraction model taking into account the speciation in the aqueous phase. This model allowed to

Cr(VI) reduction and immobilization by novel carbonaceous modified magnetic Fe_3O_4/halloysite nanohybrid

International Nuclear Information System (INIS)

Tian, Xike; Wang, Weiwei; Tian, Na; Zhou, Chaoxin; Yang, Chao; Komarneni, Sridhar

2016-01-01

Highlights: • A novel magnetic nonohybrids (Fe_3O_4/HNTs@C) were synthesized for Cr(VI) removal. • Cr(VI) was reduced to Cr(III) by Fe_3O_4 nanoparticles and hydroxyl groups. • Cr ions were attached on Fe_3O_4/HNTs@C by ion exchange and coordination interaction. - Abstract: In this work, a novel “Dumbbell-like” magnetic Fe_3O_4/Halloysite nanohybrid (Fe_3O_4/HNTs@C) with oxygen-containing organic group grafting on the surface of natural halloysite nanotubes (HNTs) and homogeneous Fe_3O_4 nanospheres selectively aggregating at the tips of modified halloysite nanotubes was successfully synthesized. XRD, TEM, IR spectroscopy, XPS and VSM were used to characterize this newly halloysite nanohybrid and its formation mechanism was discussed. Cr(VI) ions adsorption experiments showed that the Fe_3O_4/halloysite nanohybrid exhibited higher adsorption ability with a maximum adsorption capacity of 132 mg/L at 303 K, which is about 100 times higher than that of unmodified halloysite nanotubes. More importantly, with the reduction of Fe_3O_4 and electron–donor effect of oxygen-containing organic groups, Cr(VI) ions were easily reduced into low toxicity Cr(III) and then adsorbed onto the surface of halloysite nanohybrid. In addition, appreciable magnetization was observed due to the aggregation of magnetite nanoparticles, which make adsorbent facility separated from aqueous solutions after Cr pollution adsorption.

Liquid-liquid extraction and separation studies of uranium(VI)

International Nuclear Information System (INIS)

Langade, A.D.; Shinde, V.M.

1980-01-01

Separation of uranium(VI) from iron(III), molybdenum(VI), vanadium(V), bismuth(III), zirconium(IV) and thorium(IV) is achieved by liquid-liquid extraction with 4-methyl-3-pentene-2-one (mesityl oxide; MeO) from sodium salicylate media (0.1M, pH 6.0). The extracted species is UO 2 (HO.C 6 H 4 COO) 2 .2MeO. A procedure for separating 50 μg of uranium from mg amounts of the other metals is described. (author)

New generation ion-imprinted nanocarrier for removal of Cr(VI) from wastewater

International Nuclear Information System (INIS)

Uygun, Murat; Feyzioğlu, Esra; Özçalışkan, Emir; Caka, Müşerref; Ergen, Aygen; Akgöl, Sinan; Denizli, Adil

2013-01-01

The purpose of this study was to prepare a novel ion-imprinted nanoparticle to remove Cr(VI) ions from waste water. For this, Cr(VI) ions were complexed with 2-methacryloylamido histidine (MAH) and then Cr(VI)-imprinted poly(HEMAH) nanoparticles were synthesized by surfactant-free emulsion polymerization technique. The templates, Cr(VI) ions, were removed from the nanoparticles using 0.1 M of HNO 3 solution. The specific surface area of the Cr(VI)-imprinted poly(HEMAH) nanoparticles was found to be 1,397.85 m 2 /g, and the particle size was calculated as 155.3 nm. These Cr(VI)-imprinted nanoparticles were used for the adsorption/desorption of Cr(VI) ions from its aqueous solutions. The effects of initial Cr(VI) concentration and medium pH on the Cr(VI) adsorption capacity were also studied. The maximum adsorbed amount of Cr(VI) on the imprinted nanoparticles was found to be 3,830.58 mg/g nanoparticle in pH 4.0. In order to investigate the selectivity of the imprinted nanoparticle, adsorption studies were repeated using Cr(III) ions. The selectivity results demonstrated that Cr(VI)-imprinted poly(HEMAH) nanoparticles showed high affinity for the Cr(VI) ions than Cr(III). The Cr(VI)-imprinted nanoparticles were used several times without decreasing their Cr(VI) adsorption capacities

New generation ion-imprinted nanocarrier for removal of Cr(VI) from wastewater

Science.gov (United States)

Uygun, Murat; Feyzioğlu, Esra; Özçalışkan, Emir; Caka, Müşerref; Ergen, Aygen; Akgöl, Sinan; Denizli, Adil

2013-08-01

The purpose of this study was to prepare a novel ion-imprinted nanoparticle to remove Cr(VI) ions from waste water. For this, Cr(VI) ions were complexed with 2-methacryloylamido histidine (MAH) and then Cr(VI)-imprinted poly(HEMAH) nanoparticles were synthesized by surfactant-free emulsion polymerization technique. The templates, Cr(VI) ions, were removed from the nanoparticles using 0.1 M of HNO3 solution. The specific surface area of the Cr(VI)-imprinted poly(HEMAH) nanoparticles was found to be 1,397.85 m2/g, and the particle size was calculated as 155.3 nm. These Cr(VI)-imprinted nanoparticles were used for the adsorption/desorption of Cr(VI) ions from its aqueous solutions. The effects of initial Cr(VI) concentration and medium pH on the Cr(VI) adsorption capacity were also studied. The maximum adsorbed amount of Cr(VI) on the imprinted nanoparticles was found to be 3,830.58 mg/g nanoparticle in pH 4.0. In order to investigate the selectivity of the imprinted nanoparticle, adsorption studies were repeated using Cr(III) ions. The selectivity results demonstrated that Cr(VI)-imprinted poly(HEMAH) nanoparticles showed high affinity for the Cr(VI) ions than Cr(III). The Cr(VI)-imprinted nanoparticles were used several times without decreasing their Cr(VI) adsorption capacities.

New generation ion-imprinted nanocarrier for removal of Cr(VI) from wastewater

Energy Technology Data Exchange (ETDEWEB)

Uygun, Murat, E-mail: muygun@adu.edu.tr [Adnan Menderes University, Kocarl Latin-Small-Letter-Dotless-I Vocational and Training School (Turkey); Feyzioglu, Esra; Oezcal Latin-Small-Letter-Dotless-I skan, Emir; Caka, Mueserref; Ergen, Aygen; Akgoel, Sinan [Ege University, Department of Biochemistry, Faculty of Science (Turkey); Denizli, Adil [Hacettepe University, Department of Chemistry, Faculty of Science (Turkey)

2013-08-15

The purpose of this study was to prepare a novel ion-imprinted nanoparticle to remove Cr(VI) ions from waste water. For this, Cr(VI) ions were complexed with 2-methacryloylamido histidine (MAH) and then Cr(VI)-imprinted poly(HEMAH) nanoparticles were synthesized by surfactant-free emulsion polymerization technique. The templates, Cr(VI) ions, were removed from the nanoparticles using 0.1 M of HNO{sub 3} solution. The specific surface area of the Cr(VI)-imprinted poly(HEMAH) nanoparticles was found to be 1,397.85 m{sup 2}/g, and the particle size was calculated as 155.3 nm. These Cr(VI)-imprinted nanoparticles were used for the adsorption/desorption of Cr(VI) ions from its aqueous solutions. The effects of initial Cr(VI) concentration and medium pH on the Cr(VI) adsorption capacity were also studied. The maximum adsorbed amount of Cr(VI) on the imprinted nanoparticles was found to be 3,830.58 mg/g nanoparticle in pH 4.0. In order to investigate the selectivity of the imprinted nanoparticle, adsorption studies were repeated using Cr(III) ions. The selectivity results demonstrated that Cr(VI)-imprinted poly(HEMAH) nanoparticles showed high affinity for the Cr(VI) ions than Cr(III). The Cr(VI)-imprinted nanoparticles were used several times without decreasing their Cr(VI) adsorption capacities.

Contribution of extracellular polymeric substances from Shewanella sp. HRCR-1 biofilms to U(VI) immobilization.

Science.gov (United States)

Cao, Bin; Ahmed, Bulbul; Kennedy, David W; Wang, Zheming; Shi, Liang; Marshall, Matthew J; Fredrickson, Jim K; Isern, Nancy G; Majors, Paul D; Beyenal, Haluk

2011-07-01

The goal of this study was to quantify the contribution of extracellular polymeric substances (EPS) to U(VI) immobilization by Shewanella sp. HRCR-1. Through comparison of U(VI) immobilization using cells with bound EPS (bEPS) and cells with minimal EPS, we show that (i) bEPS from Shewanella sp. HRCR-1 biofilms contribute significantly to U(VI) immobilization, especially at low initial U(VI) concentrations, through both sorption and reduction; (ii) bEPS can be considered a functional extension of the cells for U(VI) immobilization and they likely play more important roles at lower initial U(VI) concentrations; and (iii) the U(VI) reduction efficiency is dependent upon the initial U(VI) concentration and decreases at lower concentrations. To quantify the relative contributions of sorption and reduction to U(VI) immobilization by EPS fractions, we isolated loosely associated EPS (laEPS) and bEPS from Shewanella sp. HRCR-1 biofilms grown in a hollow fiber membrane biofilm reactor and tested their reactivity with U(VI). We found that, when reduced, the isolated cell-free EPS fractions could reduce U(VI). Polysaccharides in the EPS likely contributed to U(VI) sorption and dominated the reactivity of laEPS, while redox active components (e.g., outer membrane c-type cytochromes), especially in bEPS, possibly facilitated U(VI) reduction.

Balanç benefici/risc del contingut en polifenols i alcohol del vi: bases científiques dels efectes del consum moderat de vi sobre el sistema cardiovascular

OpenAIRE

Chiva Blanch, Gemma

2013-01-01

[cat] L'objectiu d'aquesta tesi doctoral és avaluar els efectes de les fraccions del vi (alcohòlica i no alcohòlica -principalment polifenols-) sobre els principals factors de risc cardiovascular en 67 homes amb un elevat risc de patir malalties cardiovasculars. Es va realitzar un assaig clínic, aleatoritzat i creuat en el qual tots els participants van rebre en un ordre aleatori les tres intervencions: 30 gr d'alcohol / dia en forma de vi negre, la mateixa quantitat de polifenols en forma de...

Contribution of Extracellular Polymeric Substances from Shewanella sp. HRCR-1 Biofilms to U(VI) Immobilization

Energy Technology Data Exchange (ETDEWEB)

Cao, Bin; Ahmed, B.; Kennedy, David W.; Wang, Zheming; Shi, Liang; Marshall, Matthew J.; Fredrickson, Jim K.; Isern, Nancy G.; Majors, Paul D.; Beyenal, Haluk

2011-06-05

The goal of this study was to quantify the contribution of extracellular polymeric substances (EPS) in U(VI) immobilization by Shewanella sp. HRCR-1. Through comparison of U(VI) immobilization using cells with bound EPS (bEPS) and cells without EPS, we showed that i) bEPS from Shewanella sp. HRCR-1 biofilms contributed significantly to U(VI) immobilization, especially at low initial U(VI) concentrations, through both sorption and reduction; ii) bEPS could be considered as a functional extension of the cells for U(VI) immobilization and they likely play more important roles at initial U(VI) concentrations; and iii) U(VI) reduction efficiency was found to be dependent upon initial U(VI) concentration and the efficiency decreased at lower concentrations. To quantify relative contribution of sorption and reduction in U(VI) immobilization by EPS fractions, we isolated loosely associated EPS (laEPS) and bEPS from Shewanella sp. HRCR-1 biofilms grown in a hollow fiber membrane biofilm reactor and tested their reactivity with U(V). We found that, when in reduced form, the isolated cell-free EPS fractions could reduce U(VI). Polysaccharides in the EPS likely contributed to U(VI) sorption and dominated reactivity of laEPS while redox active components (e.g., outer membrane c-type cytochromes), especially in bEPS, might facilitate U(VI) reduction.

Uranium(VI) retention on quartz and kaolinite. Experiments and modelling

International Nuclear Information System (INIS)

Mignot, G.

2001-01-01

The behaviour of uranium in the geosphere is an important issue for safety performance assessment of nuclear waste repositories, or in the context of contaminated sites due to mining activity related to nuclear field. Under aerobic conditions, the fate of uranium is mainly governed by the ability of minerals to sorb U(VI) aqueous species. Hence, a thorough understanding of U(VI) sorption processes on minerals is required to provide a valuable prediction of U(VI) migration in the environment. In this study, we performed sorption/desorption experiments of U(VI) on quartz and kaolinite, for systems favouring the formation in solution (i) of UO 2 2+ and monomeric hydrolysis products or (ii) of di-/tri-meric uranyl aqueous species, and / or U(VI)-colloids or UO 2 (OH) 2 precipitates, or (iii) of uranyl-carbonate complexes. Particular attention was paid to determine the surface characteristics of the solids and their modification due to dissolution/precipitation processes during experiments. A double layer surface complexation model was applied to our experimental data in order to derive surface complexation equilibria and intrinsic constants which allow a valuable description of U(VI) retention over a wide range of pH, ionic strength, initial concentration of uranium [0.1-10μM] and solid - solution equilibration time. U(VI) sorption on quartz was successfully modeled by using two sets of adsorption equilibria, assuming (i) the formation of the surface complexes SiOUO 2 + , SiOUO 2 OH and SiO(UO 2 ) 3 (OH) 5 , or (ii) the formation of the mono-dentate complex SiO(UO 2 ) 3 (OH) 5 and of the bidentate complex (SiO) 2 UO 2 . Assumptions on the density of each type of surface sites of kaolinite and on their acid-base properties were made from potentiometric titrations of kaolinite suspensions. We proposed on such a basis a set of surface complexation equilibria which accounts for U(VI) uptake on kaolinite over a wide range of chemical conditions, with aluminol edge sites as

Electrochemistry and Spectroelectrochemistry of the Pu (III/IV) and (IV/VI) Couples in Nitric Acid Systems

Energy Technology Data Exchange (ETDEWEB)

Lines, Amanda M. [Nuclear Chemistry and Engineering, Pacific Northwest National Laboratory, Richland WA 99352; Adami, Susan R. [Nuclear Chemistry and Engineering, Pacific Northwest National Laboratory, Richland WA 99352; Casella, Amanda J. [Nuclear Chemistry and Engineering, Pacific Northwest National Laboratory, Richland WA 99352; Sinkov, Sergey I. [Nuclear Chemistry and Engineering, Pacific Northwest National Laboratory, Richland WA 99352; Lumetta, Gregg J. [Nuclear Chemistry and Engineering, Pacific Northwest National Laboratory, Richland WA 99352; Bryan, Samuel A. [Nuclear Chemistry and Engineering, Pacific Northwest National Laboratory, Richland WA 99352

2017-09-20

The solution chemistry of Pu in nitric acid is explored via electrochemistry and spectroelectrochemistry. By utilizing and comparing these techniques, an improved understanding of Pu behavior and its dependence on nitric acid concentration can be achieved. Here the Pu (III/IV) couple is characterized using cyclic voltammetry, square wave voltammetry, and a spectroelectrochemical Nernst step. Results indicate the formal reduction potential of the couple shifts negative with increasing acid concentration and reversible electrochemistry is no longer attainable above 6 M HNO3. Spectroelectrochemistry is also used to explore the irreversible oxidation of Pu(IV) to Pu(VI) and shine light on the mechanism and acid dependence of the redox reaction.

Synthesis and characterization of chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), cadmium(II) and dioxouranium(VI) complexes of 4(2-pyridyl)-1-(2,4-dihydroxybenzaldehyde)-3-thiosemicarbazone

International Nuclear Information System (INIS)

Abu El-Reash, G.M.; Ibrahim, M.M.; Kenawy; El-Ayaan, Usama; Khattab, M.A.

1994-01-01

A few complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and dioxouranium(VI) with 4(2-pyridyl)-1-(2,4-dihydroxybenzaldehyde)-3-thiosemicarbazone have been synthesised and characterized on the basis of elemental analysis, IR, electronic NMR, and magnetic moment data. An octahedral structure is proposed for the Cr(III), Fe(III), Co(II) and Ni(H 3 PBT) 2 Cl 2 .2H 2 O complexes; a tetrahedral structure for the Mn(II) and Ni 2 (PBT)OAc.H 2 0 complexes and a square planar structure for the Cu(II) complexes. The antimicrobial and antifungal activities of H 3 PBT and of its metal(II) complexes are investigated. The results reveal that H 3 PBT exhibits greater antimicrobial activities than its complexes. (author). 34 refs., 4 figs., 2 tabs

Cinética e equilíbrio de adsorção dos oxiânions Cr (VI, Mo (VI e Se (VI pelo sal de amônio quaternário de quitosana Kinetics and equilibrium of adsorption of oxyanions Cr (VI, Mo (VI and Se (VI by quaternary ammonium chitosan salt

Directory of Open Access Journals (Sweden)

Viviane A. Spinelli

2005-07-01

Full Text Available O sal quaternário de quitosana foi sintetizado com cloreto de glicidil trimetil amônio. A modificação química foi caracterizada por espectrometria no IV, RMN de 13C e ¹H, e mmol/g de grupos quaternários presentes na matriz polimérica por condutimetria. A remoção de Cr (VI, Mo (VI e Se (VI, em meio aquoso, foi investigada em processo de batelada. A adsorção mostrou ser dependente do pH para o Cr (VI e Se (VI, com um pH ótimo de adsorção, entre 4,0 a 6,0. Para o Mo (VI a adsorção manteve-se quase constante no intervalo de pH entre 4,0 e 11,5. O modelo de isoterma de Langmuir descreveu melhor os dados de equilíbrio na faixa de concentração investigada. No presente estudo, um grama do sal quaternário de quitosana reticulado com glutaraldeído adsorveu 68,3 mg de Cr, 63,4 mg de Mo e 90,0 mg de Se. A velocidade de adsorção, no processo, segue a equação cinética de pseudo segunda-ordem, sendo que o equilíbrio para os três íons foi alcançado próximo aos 200 minutos. A análise dispersiva de raios-X para o Cr (VI mostrou que o principal mecanismo de adsorção é a troca iônica entre os íons Cl- da superfície do polímero pelos oxiânions. O trocador aniônico apresentou a seguinte ordem de seletividade: Cr (VI > Mo (VI > Se (VI.Quaternary chitosan salt was synthesized in the presence of glycidyl trimetyl ammonium chloride. The polymer was characterized by spectroscopic techniques: infrared, 13C and ¹H NMR, while the amount of quaternary ammonium groups was obtained by condutimetry. The removal of Cr (VI, Mo (VI and Se (VI from aqueous solutions was carried out in batch adsorption processes. The process seemed to be pH dependent for Cr (VI and Se (VI with an optimum pH ranging from 4.0 to 6.0; while for Mo (VI the adsorption remained almost constant within the range between 4.0 and 11.5. The Langmuir isotherm model provided the best fit of the equilibrium data over the whole concentration investigated. In the experiment

Separation method for ions of elements of the III., IV., VI. and VIII. groups of periodical system

International Nuclear Information System (INIS)

Marhol, M.

1973-01-01

The method is presented of separating the ions of the elements of the periodic system groups III, IV, and VIII by ion exchangers. The ions are complex-bonded to a new type of ion exchanger consisting of the polycondensates of phenol with aldehydes or ketones and containing an atom of phosphorus, arsenic or antimony with an atom of sulphur or oxygen in a complex bond. The polymers of compounds containing a double bond, e.g., of butadiene, polyvinyl alcohol, polyethylene, polypropylene, and the compounds of styrene with fural may also be used for this purpose. The method is demonstrated on a case of uranium and heavy metal concentration and the separation thereof from waste waters. (L.K.)

Technology-derived storage solutions for stabilizing insulin in extreme weather conditions I: the ViViCap-1 device.

Science.gov (United States)

Pfützner, Andreas; Pesach, Gidi; Nagar, Ron

2017-06-01

Injectable life-saving drugs should not be exposed to temperatures 30°C/86°F. Frequently, weather conditions exceed these temperature thresholds in many countries. Insulin is to be kept at 4-8°C/~ 39-47°F until use and once opened, is supposed to be stable for up to 31 days at room temperature (exception: 42 days for insulin levemir). Extremely hot or cold external temperature can lead to insulin degradation in a very short time with loss of its glucose-lowering efficacy. Combined chemical and engineering solutions for heat protection are employed in ViViCap-1 for disposable insulin pens. The device works based on vacuum insulation and heat consumption by phase-change material. Laboratory studies with exposure of ViViCap-1 to hot outside conditions were performed to evaluate the device performance. ViViCap-1 keeps insulin at an internal temperature phase-change process and 'recharges' the device for further use. ViViCap-1 performed within its specifications. The small and convenient device maintains the efficacy and safety of using insulin even when carried under hot weather conditions.

Defects and oxidation of group-III monochalcogenide monolayers

Science.gov (United States)

Guo, Yu; Zhou, Si; Bai, Yizhen; Zhao, Jijun

2017-09-01

Among various two-dimensional (2D) materials, monolayer group-III monochalcogenides (GaS, GaSe, InS, and InSe) stand out owing to their potential applications in microelectronics and optoelectronics. Devices made of these novel 2D materials are sensitive to environmental gases, especially O2 molecules. To address this critical issue, here we systematically investigate the oxidization behaviors of perfect and defective group-III monochalcogenide monolayers by first-principles calculations. The perfect monolayers show superior oxidation resistance with large barriers of 3.02-3.20 eV for the dissociation and chemisorption of O2 molecules. In contrast, the defective monolayers with single chalcogen vacancy are vulnerable to O2, showing small barriers of only 0.26-0.36 eV for the chemisorption of an O2 molecule. Interestingly, filling an O2 molecule to the chalcogen vacancy of group-III monochalcogenide monolayers could preserve the electronic band structure of the perfect system—the bandgaps are almost intact and the carrier effective masses are only moderately disturbed. On the other hand, the defective monolayers with single vacancies of group-III atoms carry local magnetic moments of 1-2 μB. These results help experimental design and synthesis of group-III monochalcogenides based 2D devices with high performance and stability.

Removal of Cr(VI) ions by sewage sludge compost biomass from aqueous solutions: Reduction to Cr(III) and biosorption

Science.gov (United States)

Chen, Huixia; Dou, Junfeng; Xu, Hongbin

2017-12-01

Sewage sludge compost biomass was used as a novel biosorbent to remove hexavalent chromium from water. Surface area analysis, scanning electron microscopy, fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and point zero charge was applied to study the microstructure, compositions and chemical bonding states of the biomass adsorbent. Effects of contact time, biomass dosage, agitation speed, pH, the initial concentration of Cr(VI) and Cr(Ⅲ) on its adsorption removal were also performed in the batch experiments. A model describing adsorption, desorption and reduction phenomena during the sorption process has been referenced to model Cr(VI) sorption onto sewage sludge compost biomass. The result of characterization test shows that adsorption of Cr(VI) onto sewage sludge compost biomass followed by the partial reduction to Cr(Ⅲ) by biomass groups such as hydroxyl, carboxyl, and amino groups. The absorption kinetics model in the description of adsorption-coupled reduction of Cr(VI) fits successfully the kinetic data obtained at different temperatures and describes the kinetics profile of total, hexavalent and trivalent chromium. The study shows that sewage sludge compost biomass could be used as a potential biosorbent for removal of hexavalent chromium from wastewaters.

Fluorescent silver nanoclusters for ultrasensitive determination of chromium(VI) in aqueous solution

International Nuclear Information System (INIS)

Zhang, Jian Rong; Zeng, Ai Lian; Luo, Hong Qun; Li, Nian Bing

2016-01-01

Highlights: • Fluorescent Ag nanoclusters were first applied to Cr(VI) detection. • The proposed method is simple, rapid, and environmentally friendly. • The sensor shows a wide linear range, low detection limit, and good selectivity. • The system can also be used for the indirect assay of total chromium and Cr(III). • The analyses in real water samples are satisfactory. - Abstract: In this work, a simple and sensitive Cr(VI) sensor is proposed based on fluorescent polyethyleneimine-stabilized Ag nanoclusters, which allows the determination over a wide concentration range of 0.1 nM–3.0 μM and with a detection limit as low as 0.04 nΜ and a good selectivity. The quenching mechanism was discussed in terms of the absorption and fluorescence spectra, suggesting that Cr(VI) is connected to Ag nanoclusters by hydrogen bond between the oxygen atom at the vertex of tetrahedron structure of Cr(VI) and the amino nitrogen of polyethyleneimine that surrounded Ag nanoclusters and electron transfer from Ag nanoclusters to highly electron-deficient Cr(VI) results in fluorescence quenching. Despite the failure to quench the fluorescence efficiently, Cr(III) can also be measured using the proposed Ag nanoclusters by being oxidized to Cr(VI) in alkaline solution (pH ∼9) containing H 2 O 2 . Therefore, our approach could be used to detect Cr(VI), Cr(III) and the total chromium level in aqueous solution. In addition, Cr(VI) analysis in real water samples were satisfactory, indicating this method could be practically promising for chromium measurements.

Structural features and electronic properties of group-III-, group-IV-, and group-V-doped Si nanocrystallites

International Nuclear Information System (INIS)

Ramos, L E; Degoli, Elena; Cantele, G; Ossicini, Stefano; Ninno, D; Furthmueller, J; Bechstedt, F

2007-01-01

We investigate the incorporation of group-III (B and Al), group-IV (C and Ge), and group-V (N and P) impurities in Si nanocrystallites. The structural features and electronic properties of doped Si nanocrystallites, which are faceted or spherical-like, are studied by means of an ab initio pseudopotential method including spin polarization. Jahn-Teller distortions occur in the neighborhood of the impurity sites and the bond lengths show a dependence on size and shape of the nanocrystallites. We find that the acceptor (group-III) and donor (group-V) levels become deep as the nanocrystallites become small. The energy difference between the spin-up and spin-down levels of group-III and group-V impurities decreases as the size of the Si nanocrystallite increases and tends to the value calculated for Si bulk. Doping with carbon introduces an impurity-related level in the energy gap of the Si nanocrystallites

DAPPA grafted polymer: an efficient solid phase extractant for U(VI), Th(IV) and La(III) from acidic waste streams and environmental samples.

Science.gov (United States)

Raju, Ch Siva Kesava; Subramanian, M S

2005-07-15

A new class of polymeric resin has been synthesized by grafting Merrifield chloromethylated resin with (dimethyl amino-phosphono-methyl)-phosphonic acid (MCM-DAPPA), for the preconcentration of U(VI), Th(IV) and La(III) from both acidic wastes and environmental samples. The various chemical modification steps involved during grafting process are characterized by FT-IR spectroscopy, (31)P and (13)C-CPMAS (cross-polarized magic angle spin) NMR spectroscopy and CHNS/O elemental analysis. The water regain capacity data for the grafted polymer are obtained from thermo-gravimetric (TG) analysis. The influence of various physico-chemical parameters during the quantitative extraction of metal ions by the resin phase are studied and optimized by both static and dynamic methods. The significant feature of this grafted polymer is its ability to extract both actinides and lanthanides from high-level acidities as well as from near neutral conditions. The resin shows very high sorption capacity values of 2.02, 0.89 and 0.54mmolg(-1) for U(VI), 1.98, 0.63 and 0.42mmolg(-1) for Th(IV) and 1.22, 0.39 and 0.39mmolg(-1) for La(III) under optimum pH, HNO(3) and HCl concentration, respectively. The grafted polymer shows faster phase exchange kinetics (99.5% recovery using 1M (NH(4))(2)CO(3), as eluent. The developed grafted resin has been successfully applied in extracting Th(IV) from high matrix monazite sand, U(VI) from sea water and also U(VI) and Th(IV) from simulated nuclear spent fuel mixtures. The analytical data obtained from triplicate measurements are within 3.9% R.S.D. reflecting the reproducibility and reliability of the developed method.

Negative impact of oxygen molecular activation on Cr(VI) removal with core–shell Fe@Fe2O3 nanowires

International Nuclear Information System (INIS)

Mu, Yi; Wu, Hao; Ai, Zhihui

2015-01-01

Highlights: • The presence of oxygen inhibited Cr(VI) removal efficiency with nZVI by near 3 times. • Cr(VI) removal with nZVI was related to adsorption, reduction, co-precipitation, and adsorption reactions. • Molecular oxygen activation competed donor electrons from Fe 0 core and surface bound Fe(II) of nZVI. • Thicker Cr(III)/Fe(III)/Cr(VI) oxyhydroxides shell of nZVI leaded to the electron transfer inhibition. - Abstract: In this study, we demonstrate that the presence of oxygen molecule can inhibit Cr(VI) removal with core–shell Fe@Fe 2 O 3 nanowires at neutral pH of 6.1. 100% of Cr(VI) removal was achieved by the Fe@Fe 2 O 3 nanowires within 60 min in the anoxic condition, in contrast, only 81.2% of Cr(VI) was sequestrated in the oxic condition. Removal kinetics analysis indicated that the presence of oxygen could inhibit the Cr(VI) removal efficiency by near 3 times. XRD, SEM, and XPS analysis revealed that either the anoxic or oxic Cr(VI) removal was involved with adsorption, reduction, co-precipitation, and re-adsorption processes. More Cr(VI) was bound in a reduced state of Cr(III) in the anoxic process, while a thicker Cr(III)/Fe(III)/Cr(VI) oxyhydroxides shell, leading to inhibiting the electron transfer, was found under the oxic process. The negative impact of oxygen molecule was attributed to the oxygen molecular activation which competed with Cr(VI) adsorbed for the consumption of donor electrons from Fe 0 core and ferrous ions bound on the iron oxides surface under the oxic condition. This study sheds light on the understanding of the fate and transport of Cr(VI) in oxic and anoxic environment, as well provides helpful guide for optimizing Cr(VI) removal conditions in real applications

The toxicity of arsenic(III), chromium(VI) and zinc to groundwater copepods.

Science.gov (United States)

Hose, G C; Symington, K; Lott, M J; Lategan, M J

2016-09-01

Groundwater ecosystems globally are threatened by anthropogenic contamination, yet there are few ecotoxicological data using obligate groundwater biota on which to base risk assessments. Copepods are found inhabiting aquifers of different geologies around the world and so are a useful taxon for use in ecotoxicological studies of groundwater. The aim of this study was to test the sensitivity of obligate groundwater copepods to metal contaminants (arsenic(III), chromium(VI) and zinc) in groundwater in static 96 h, 14 days and 28 days exposure tests. The copepods were variably sensitive to As, Cr and Zn, with Cr being the most toxic across all taxa. No taxon was consistently most sensitive and there was no apparent relationship between the hardness, pH and organic carbon concentration of the diluent water and the sensitivity of biota. As expected, toxicity increased with exposure period and we encourage the use of longer exposure periods in future toxicity tests with groundwater organisms to reflect the greater exposure periods likely to be associated with groundwater contamination.

A study on selective precipitation of U(VI) by hydrophilic cyclic urea derivatives for development of a reprocessing system based on precipitation method

International Nuclear Information System (INIS)

Suzuki, Tomoya; Takao, Koichiro; Kawasaki, Takeshi; Harada, Masayuki; Ikeda, Yasuhisa; Nogami, Masanobu

2014-01-01

Selective precipitation ability of 2-imidazolidone (EU) and tetrahydro-2-pyrimidinone (PU) for U(VI) species in HNO 3 solutions containing U(VI), U(IV) (simulant of Pu(IV)), and simulated fission products (FPs) was investigated. As a result, it was found that these compounds precipitate almost quantitatively U(VI) as UO 2 (NO 3 ) 2 L 2 (L = EU, PU) from 3.0 M HNO 3 solution. In contrast, these urea derivatives form neither solid precipitates nor oily products with U(IV) in HNO 3 solutions containing only U(IV) species and even in U(VI)-U(IV) admixture system. Therefore, the separation of U(VI) from U(IV) was demonstrated to be achieved in use of EU and PU. Furthermore, EU and PU are capable to remove most of simulated FPs[Sr(II), Ru(III), Rh(III), Re(VII) La(III), Ce(III), Pr(III), Nd(III), and Sm(III)] from U(VI) to give their decontamination factors (DFs) higher than 100, while those values of Zr(IV), Mo(VI), Pd(II), and Ba(II) are necessary to be improved in both systems. From these results, it is expected that EU and PU are the promising precipitants for selective separation of U(VI) from HNO 3 solutions dissolving spent FBR fuels. (author)

Blood groups and acute aortic dissection type III.

Science.gov (United States)

Fatic, Nikola; Nikolic, Aleksandar; Vukmirovic, Mihailo; Radojevic, Nemanja; Zornic, Nenad; Banzic, Igor; Ilic, Nikola; Kostic, Dusan; Pajovic, Bogdan

2017-04-01

Acute aortic type III dissection is one of the most catastrophic events, with in-hospital mortality ranging between 10% and 12%. The majority of patients are treated medically, but complicated dissections, which represent 15% to 20% of cases, require surgical or thoracic endovascular aortic repair (TEVAR). For the best outcomes adequate blood transfusion support is required. Interest in the relationship between blood type and vascular disease has been established. The aim of our study is to evaluate distribution of blood groups among patients with acute aortic type III dissection and to identify any kind of relationship between blood type and patient's survival. From January 2005 to December 2014, 115 patients with acute aortic type III dissection were enrolled at the Clinic of Vascular and Endovascular Surgery in Belgrade, Serbia and retrospectively analyzed. Patients were separated into two groups. The examination group consisted of patients with a lethal outcome, and the control group consisted of patients who survived. The analysis of the blood groups and RhD typing between groups did not reveal a statistically significant difference ( p = 0.220). Our results indicated no difference between different blood groups and RhD typing with respect to in-hospital mortality of patients with acute aortic dissection type III.

The Effect of the Concentration of Oxidant, Cr(VI), on the Iron Oxidation in Saline Water

Science.gov (United States)

Ahn, H.; Jo, H. Y.; Ryu, J. H.; Koh, Y. K.

2014-12-01

Deep geological disposal is currently considered as the most appropriate method to isolate high level radioactive wastes (HLRWs) from the ecosystem. If groundwater seeps into underground disposal facilities, water molecules can be dissociated to radicals or peroxides, which can oxidize metal canisters and HLRWs. The oxidized radionuclides with a high solubility can be dissolved in the groundwater. Some dissolved radionuclides can act as oxidants. The continuous radiolysis of water molecules, which results from continuous seepage of groundwater, can enable the continuous production of the radioactive oxidants, resulting in an increase in concentration of oxidants. In this study, the effect of oxidant concentration on iron oxidation in the presence of salt was evaluated. Zero valent iron (ZVI) particles were reacted with Cr(VI) solutions with initial Cr(VI) concentrations ranged from 50 to 300 mg/L in reactors. The initial pH and NaCl concentration were fixed at 3 and 0.5 M, respectively. An increase in the initial Cr(VI) concentration caused an increase in the rate and extend of H2 gas production. The decrement of Cr(VI) was increased as the initial Cr(VI) concentration was increased. The penetration of H+ ions in the presence Cl- ions through the passive film on the ZVI particles caused the reaction between H+ ions and ZVI particles, producing H2 gas and Fe2+ ions. The passive film was damaged during the reaction due to the eruption of H2 gas or peptization by Cl- ions. The Fe2+ ions were reacted with Cr(VI) ions in the solution, producing Fe(III)-Cr(III) (oxy)hydroxides on the passive film of ZVI particles or in the solution as colloidal particles. The Fe(III)-Cr(III) (oxy)hydroxides tends to be precipitated as colloidal particles at a high Cr(VI) concentration and precipitated on the passive film at a low Cr(VI) concentration. The passive film was repaired or thickened by additional formation of Fe(III)-Cr(III) (oxy)hydroxides at a lower Cr(VI) concentration.

Removal of Cr(VI) from aqueous solution by flocculant with the capacity of reduction and chelation

International Nuclear Information System (INIS)

Wang, Gang; Chang, Qing; Han, Xiaoting; Zhang, Mingyue

2013-01-01

Highlights: ► We report a novel flocculant with the properties of reduction and chelation for Cr. ► The removal of Cr(VI) by the flocculant depends highly on pH value. ► Some coexisting ions inhibit Cr (VI) removal, but promote total Cr removal. ► Cr and turbidity can be removed simultaneously in the treated wastewater. ► The interaction mechanism is investigated by FTIR and SEM. -- Abstract: A novel agent polyethyleneimine-sodium xanthogenate (PEX) with the multifunction of reduction, chelation, flocculation and precipitation was synthesized by using polyethyleneimine (PEI), carbon disulfide (CS 2 ), and sodium hydroxide (NaOH). The effects of different important parameters, such as pH value, initial Cr(VI) concentration, coexisting ions and turbidity etc., on the removal of chromium from aqueous solution by PEX were investigated in flocculation experiments. The experiments results demonstrated that PEX could efficiently remove Cr(VI) and total Cr (Cr(VI) + Cr(III)) in strongly acidic media. It was proved that the presence of coexisting ions (Na + , Ca 2+ , F − , Cl − , and SO 4 2− ) in the solution had a little influence on the removal of chromium. Furthermore, it was conformed that Cr(VI) ions and turbidity could be simultaneously removed when water samples contained both Cr(VI) ions and turbidity. Finally, the mechanism of interaction between chromium and PEX was further confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results reveal that dithiocarboxylic acid groups on PEX macromolecule play a major role in Cr(VI) reduction and Cr(III) chelation, and the flocs formation is attributed to the interparticle bridging mechanism of PEX

Bringing part of the lab to the field: On-site chromium speciation in seawater by electrodeposition of Cr(III)/Cr(VI) on portable coiled-filament assemblies and measurement in the lab by electrothermal, near-torch vaporization sample introduction and inductively coupled plasma-atomic emission spectrometry

International Nuclear Information System (INIS)

Badiei, Hamid R.; McEnaney, Jennifer; Karanassios, Vassili

2012-01-01

A field-deployable electrochemical approach to preconcentration, matrix clean up and selective electrodeposition of Cr(III) and Cr(III) + Cr(VI) in seawater is described. Using portable, battery-operated electrochemical instrumentation, Cr species in seawater were electrodeposited in the field on portable coiled-filament assemblies made from Re. Assemblies with dried residues of Cr(III) or Cr(III) + Cr(VI) on them were transported to the lab for concentration determination by electrothermal, near-torch vaporization (NTV) sample introduction and inductively coupled plasma-atomic emission spectrometry (ICP-AES). Electrodeposition offers selective species deposition, preconcentration and matrix clean up from seawater samples. For selective deposition, free Cr(VI) was electrodeposited at − 0.3 V and Cr(III) + Cr(VI) at − 1.6 V (both vs Ag/AgCl). Interestingly, at 0 V (vs Ag/AgCl) and in the absence of an electrodeposition potential only Cr(VI) was spontaneously and selectively adsorbed on the coil and reasons for this are given. Due to preconcentration afforded by electrodeposition, the detection limits obtained after a 60 s electrodeposition at the voltages stated above using buffered (pH = 4.7) artificial seawater spiked with either Cr(III) or Cr(VI) were 20 pg/mL for Cr(III) and 10 pg/mL for Cr(VI). For comparison, the detection limit for Cr obtained by pipetting directly on the coil 5 μL of diluted standard solution was 500 pg/mL, thus it was concluded that electrodeposition offered 40 to 60 fold improvements. Matrix clean up is required due to the high salt content of seawater and this was addressed by simply rinsing the coil with 18.2 MΩ water without any loss of Cr species. Reasons for this are provided. The method was validated in the lab using buffered artificial seawater and it was used in the field for the first time by sampling seawater, buffering it and immediately electrodepositing Cr species on portable assemblies on-site. Electrodeposition in the

Elemental sulfur amendment decreases bio-available Cr-VI in soils impacted by leather tanneries.

Science.gov (United States)

Shi, Jingjing; Chen, Hualin; Arocena, Joselito M; Whitcombe, Todd; Thring, Ronald W; Memiaghe, Jeff Nze

2016-05-01

This study investigated the potential use of elemental S (S(0)) to convert Cr-VI to Cr-III which should decrease the bio-availability hence, toxicity of Cr-VI in soils. The bio-available fraction of Cr in soil was measured by phosphate buffer extraction (PBE) and the results showed that the fraction is about 10% of the total Cr-VI and varied from 12.8 to 42.5 mg kg(-1). The addition of 4.0 mg g(-1) S(0) decreased PBE Cr-VI to soils. Synchrotron-based X-ray absorption near-edge structure (XANES), X-ray fluorescence (XRF) and micro-XRD revealed that Cr-III was the dominant species (99% of total Cr) and Cr was retained by hematite and goethite in soil. Fe-containing minerals may have provided sufficient protection to render the dominant Cr-III species biochemically inert to redox processes in soils. It is concluded that S(0)amendment is a promising approach to remediate Cr-VI contaminated soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of chemical compositions and molecular weights of humic acids on Cr(VI) photo-reduction

International Nuclear Information System (INIS)

Chen, S.Y.; Huang, S.W.; Chiang, P.N.; Liu, J.C.; Kuan, W.H.; Huang, J.H.; Hung, J.T.; Tzou, Y.M.; Chen, C.C.; Wang, M.K.

2011-01-01

Highlights: ► Low molecular weights (M w ) of HA bear more polar and aromatic C in its structure. ► The polar sites of HA dominate the photo-reduction of Cr(VI). ► Low M w of HA exhibits greater photochemical efficiency for Cr(VI) reduction. ► Cr(VI) adsorption on HA is indiscernible, particularly on the small M w of HA. ► Upon Cr(VI) reduction by HA, most of Cr(III) are released into the solution. - Abstract: Humic acids (HA) strongly affect the fate of trace metals in soils and aquatic environments. One of the remarkable properties of HA is its ability to reduce Cr(VI), an extremely toxic anion. However, it is unclear which HA components are involved in Cr(VI) reduction and possess the photo-induced properties. In this study, an ultrafiltration technique was used to fractionate HAs into four fractions of different nominal molecular weights (M w ): >100, 50–100, 10–50 and w HA was enriched with polar and aromatic domains. These polar, including polar C in aliphatic region, and aromatic groups were the major sites for Cr(VI) reduction because they disappeared rapidly upon interaction with Cr(VI). As a result, low M w of HA exhibited greater efficiency of Cr(VI) reduction. Light induced the rapid transfer of electrons between chromate-phenol/carboxyl ester, or the formation of peroxide radicals or H 2 O 2 through the ready decay of peroxy radicals associated with polar substituents, explained the rapid scavenging of Cr(VI) on polar and aromatic groups of HAs under illumination.

Microbial conversion of Cr (VI) in to Cr (III) in industrial effluent ...

African Journals Online (AJOL)

These bacterial strains also take up and reduce Cr (VI) present in industrial effluents, and their reduction potential was not significantly affected in the presence of different metallic salts. Key Words: Cr (VI) reduction, bacteria, industrial effluent, heavy metals. African Journal of Biotechnology Vol.3(11) 2004: 610-617 ...

Reducing elution in anion exchange chromatography as a pretreatment of colorimetry of chromium(VI) and vanadium(V)

International Nuclear Information System (INIS)

Shigetomi, Yasumasa; Hatamoto, Takeji; Nagoshi, Kimie; Yamashige, Takashi.

1976-01-01

In order to increase the selectivity of the colorimetry of chromium and vanadium, the separation by means of anion exchange chromatography was tested. The column, phi 0.8x5.0 cm packing (50--100 mesh) Dowex 1x4 anion exchange resin was used for the separation of chromium. The solution containing chromium (VI), zinc(II), cadmium(II), iron(III) and reducing organic substances contained in industrial waste water was introduced into the column and then the substances other than chromium(VI) were removed by washing the column with distilled water. Finally chromium(VI) was reduced to chromium(III) by hydroxylamine in the eluent and eluted. The concentration of sulfuric acid and hydroxylamine in the eluent were 0.1 mol/l and 0.001 mol/l respectively. For analyzing chromium(III) in the mixture of chromium(VI) and chromium(III), after removal of chromium(VI) it should be oxidized to chromium(VI) anion with the oxidant, e.g., sodium peroxide or hydrogen peroxide, before introducing it into the column. In terms of the pretreatment by using the acetate form resin column, chromium (VI) and chromium(III) can be determined separately in the solution whose concentration ranges from 0.05 ppm to 0.5 ppm despite the presence of contaminants, which interfere with the colorimetric determination of chromium(VI) using diphenylcarbonohydrazide, in the original solution. The separation of vanadium(V) in the solution containing copper(II), cobalt(II) and etc. was made using the mixed solution of hydrochloric acid (2 mol/l) and hydroxylamine (0.2 mol/l) similarly to chromium(VI). In terms of the similar pretreatment vanadium could be determined precisely as far as 0.1 ppm by the colorimetry using 4-(2-pyridylazo) resorcinol despite the presence of copper(II), cobalt(II), nickel(II) and etc in the original solution. (auth.)

The reduction of U(VI) on corroded iron under anoxic conditions

International Nuclear Information System (INIS)

Cui, D.; Spahiu, K.

2002-01-01

The corrosion of iron and the interaction between corroded iron and U(VI) in anoxic conditions were investigated. The anoxic conditions were obtained by flushing an 99.97% Ar-0.03% CO 2 gas mixture through the test vessel, in which an oxygen trap and six reaction bottles containing synthetic groundwater (10 mM NaCl and 2 mM HCO 3 - .) were placed. The dark-green coloured corrosion product, formed on iron surface after three months corrosion in synthetic groundwater solutions, was identified by powder X-ray diffraction to be carbonate green rust, Fe 4 II Fe 2 III (OH) 12 CO 3 . The iron foil that reacted in a solution (10 ppm U(VI), 10 mM NaCl and 2 mM HCO 3 - ) for three months was analysed by SEM-EDS. The result shows that: (i) an uneven layer of carbonate green rust (1-5 μm thick) formed on the metallic iron; (ii) a thin (0.3 μm) uranium-rich layer deposited on top of the carbonate green rust layer; and (iii) some UO 2 crystals (3-5 μm sized) on the thin uranium layer. The experimental results proved that the U(VI) removal capacity of metal iron is not hindered by formation of a layer of carbonate green rust on the iron. Tests with cast iron and pure iron indicate that they have similar U(VI) removal capacities. At the end of experiment, U concentrations in solution approached the solubility of UO 2 (s), 10 -8 M. The stability of the carbonate green rust at the experimental conditions, pH, E h , [Fe 2+ ] and [HCO 3 - ], is discussed. (orig.)

Mechatronic systems and materials III

CERN Document Server

Gosiewski, Zdzislaw

2009-01-01

This very interesting volume is divided into 24 sections; each of which covers, in detail, one aspect of the subject-matter: I. Industrial robots; II. Microrobotics; III. Mobile robots; IV. Teleoperation, telerobotics, teleoperated semi-autonomous systems; V. Sensors and actuators in mechatronics; VI. Control of mechatronic systems; VII. Analysis of vibration and deformation; VIII. Optimization, optimal design; IX. Integrated diagnostics; X. Failure analysis; XI. Tribology in mechatronic systems; XII. Analysis of signals; XIII. Measurement techniques; XIV. Multifunctional and smart materials;

Synthesis of a 3D lanthanum(III) MOFs as a multi-chemosensor to Cr(VI)-containing anion and Fe(III) cation based on a flexible ligand

Science.gov (United States)

Ma, Yang-Min; Liu, Tong; Huang, Wen-Huan

2018-02-01

Based on La(NO3)3·6H2O and 4,4‧-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid (H3cpbda), a 3D porous MOFs, [La(cpbda)(H2O)1.5]n (1), was synthesized by hydrothermal method and further characterized by single-crystal X-ray diffraction, power X-ray diffraction, IR spectroscopy, thermal-gravimetric analysis and fluorescence spectroscopy. Owing to its good stabilities and fluorescence property, the sensing experiments on sixteen cations and eleven anions were implemented. Moreover, the further titration processes show 1 can sensitively detect the Fe(III) cation and Cr(VI)-containing anions by quenching responses.

Cr(VI) reduction and immobilization by novel carbonaceous modified magnetic Fe{sub 3}O{sub 4}/halloysite nanohybrid

Energy Technology Data Exchange (ETDEWEB)

Tian, Xike, E-mail: xktian@cug.edu.cn [Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Wang, Weiwei; Tian, Na; Zhou, Chaoxin; Yang, Chao [Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Komarneni, Sridhar [Materials Research Laboratory, Materials Research Institute and Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, PA 16802 (United States)

2016-05-15

Highlights: • A novel magnetic nonohybrids (Fe{sub 3}O{sub 4}/HNTs@C) were synthesized for Cr(VI) removal. • Cr(VI) was reduced to Cr(III) by Fe{sub 3}O{sub 4} nanoparticles and hydroxyl groups. • Cr ions were attached on Fe{sub 3}O{sub 4}/HNTs@C by ion exchange and coordination interaction. - Abstract: In this work, a novel “Dumbbell-like” magnetic Fe{sub 3}O{sub 4}/Halloysite nanohybrid (Fe{sub 3}O{sub 4}/HNTs@C) with oxygen-containing organic group grafting on the surface of natural halloysite nanotubes (HNTs) and homogeneous Fe{sub 3}O{sub 4} nanospheres selectively aggregating at the tips of modified halloysite nanotubes was successfully synthesized. XRD, TEM, IR spectroscopy, XPS and VSM were used to characterize this newly halloysite nanohybrid and its formation mechanism was discussed. Cr(VI) ions adsorption experiments showed that the Fe{sub 3}O{sub 4}/halloysite nanohybrid exhibited higher adsorption ability with a maximum adsorption capacity of 132 mg/L at 303 K, which is about 100 times higher than that of unmodified halloysite nanotubes. More importantly, with the reduction of Fe{sub 3}O{sub 4} and electron–donor effect of oxygen-containing organic groups, Cr(VI) ions were easily reduced into low toxicity Cr(III) and then adsorbed onto the surface of halloysite nanohybrid. In addition, appreciable magnetization was observed due to the aggregation of magnetite nanoparticles, which make adsorbent facility separated from aqueous solutions after Cr pollution adsorption.

78 FR 23489 - Safety Zone; V.I. Carnival Finale, St. Thomas Harbor; St. Thomas, U.S.V.I.

Science.gov (United States)

2013-04-19

... waters of St. Thomas Harbor in St. Thomas, U.S. Virgin Islands during the V.I. Carnival Finale, a... through Friday, except Federal holidays. FOR FURTHER INFORMATION CONTACT: If you have questions on this... event. The event will be held on the waters of St. Thomas Harbor, St. Thomas, U. S. Virgin Islands...

Differential pulse cathodic stripping voltammetric determination of uranium with arsenazo-III at the hanging mercury dropping electrode

Energy Technology Data Exchange (ETDEWEB)

Kadi, M.W.; El-Shahawi, M.S. [Chemistry Dept., King Abdulaziz Univ., Jeddah (Saudi Arabia)

2009-07-01

An accurate, inexpensive and less laborious controlled adsorptive accumulation of uranium(VI)-arsenazo-III on a hanging mercury drop electrode (HMDE) has been developed for uranium(VI) determination. The method is based upon the collection of uranium(VI)-arsenazo-III complex at pH 5-6 at the HMDE and subsequent direct stripping measurement of the element in the nanomolar concentration level. The cathodic peak current (i{sub p,c}) of the adsorbed complex ions of uranium(VI) was measured at -0.35 V vs. Ag/AgCl reference electrode by differential pulse cathodic stripping voltammetry (DP-CSV), proceeded by an accumulation period of 150s2.5 in Britton-Robinson buffer of pH 5. The plot of the resulting i{sub p,c} vs. uranium(VI) concentration was linear in the range 2.1 x 10{sup -9} to 9.60 x 10{sup -7} mol L{sup -1} uranium(VI) and tended to level off at above 9.6 x 10{sup -7} mol L{sup -1}. The limits of detection and quantification of uranium(VI) were found to be 4.7 x 10{sup -10} and 1.5 x 10{sup -9} mol L{sup -1}, respectively. A relative standard deviation of {+-}2.39% (n = 5) at 8.5 x 10{sup -7} mol L{sup -1} uranium(VI) was obtained. The method was validated by comparing the results with that obtained by ICP-MS method with RSD less than {+-}3.3%. The method was applied successfully for the analysis of uranium in certified reference material (IAEA soil-7), and in phosphate fertilizers. (orig.)

The C-terminal N-glycosylation sites of the human alpha1,3/4-fucosyltransferase III, -V, and -VI (hFucTIII, -V, adn -VI) are necessary for the expression of full enzyme activity.

Science.gov (United States)

Christensen, L L; Jensen, U B; Bross, P; Orntoft, T F

2000-09-01

The alpha1,3/4-fucosyltransferases are involved in the synthesis of fucosylated cell surface glycoconjugates. Human alpha1,3/4-fucosyltransferase III, -V, and -VI (hFucTIII, -V, and -VI) contain two conserved C-terminal N-glycosylation sites (hFucTIII: Asn154 and Asn185; hFucTV: Asn167 and Asn198; and hFucTVI: Asn153 and Asn184). In the present study, we have analyzed the functional role of these potential N-glycosylation sites, laying the main emphasis on the sites in hFucTIII. Tunicamycin treatment completely abolished hFucTIII enzyme activity while castanospermine treatment diminished hFucTIII enzyme activity to approximately 40% of the activity of the native enzyme. To further analyze the role of the conserved N-glycosylation sites in hFucTIII, -V, and -VI, we made a series of mutant genomic DNAs in which the asparagine residues in the potential C-terminal N-glycosylation sites were replaced by glutamine. Subsequently, the hFucTIII, -V, and -VI wild type and the mutants were expressed in COS-7 cells. All the mutants exhibited lower enzyme activity than the wild type and elimination of individual sites had different effects on the activity. The mutations did not affect the protein level of the mutants in the cells, but reduced the molecular mass as predicted. Kinetic analysis of hFucTIII revealed that lack of glycosylation at Asn185 did not change the Km values for the oligosaccharide acceptor and the nucleotide sugar donor. The present study demonstrates that hFucTIII, -V, and -VI require N-glycosylation at the two conserved C-terminal N-glycosylation sites for expression of full enzyme activity.

Cr(VI) removal from aqueous solution by dried activated sludge biomass

International Nuclear Information System (INIS)

Wu Jun; Zhang Hua; He Pinjing; Yao Qian; Shao Liming

2010-01-01

Batch experiments were conducted to remove Cr(VI) from aqueous solution using activated sludge biomass. The effects of acid pretreatment of the biomass, initial pH, biomass and Cr(VI) concentrations on Cr(VI) removal efficiency were investigated. Proton consumption during the removal process and the reducing capacity of sludge biomass were studied. The results show that acid pretreatment could significantly improve Cr(VI) removal efficiency and increase Cr(VI) reducing capacity by 20.4%. Cr(VI) removal was remarkably pH-dependent; lower pH (pH = 1, 2) facilitated Cr(VI) reduction while higher pH (pH = 3, 4) favored sorption of the converted Cr(III). Lower Cr(VI) concentration as well as higher biomass concentration could accelerate Cr(VI) removal. Cr(VI) reduction was not the only reason for proton consumption in the removal process. Pseudo-second-order adsorption kinetic model could successfully simulate Cr(VI) removal except under higher pH conditions (pH = 3, 4).

Analytical applications of resins containing amide and polyamine functional groups

International Nuclear Information System (INIS)

Orf, G.M.

1977-01-01

Resins are prepared by chemically bonding N,N-dialkylamides and polyamine functional groups to Amberlite XAD-4. These resins are applied to the concentration of metal ions from dilute aqueous solution and the rapid separation of metal ions by high-speed liquid chromatography with continuous on-line detection of the eluent stream. A dibutyl amide resin is used for the separation of uranium(VI), thorium(IV), and zirconium(IV) from each other and several other metal ions. Uranium(VI) and thorium(IV) are determined in the presence of large excesses of foreign metal ions and anions. A practical application of the amide resin is studied by determining uranium in low grade uranium ores. The amide resin is also used for the selective concentration of gold(III) from seawater. A triethylenetetramine resin is used for the separation of copper(II) from equal molar amounts and large excesses of nickel(II), cobalt(II), zinc(II), cadmium(II), iron(III) and aluminum(III). Copper(II), nickel(II), zinc(II), cobalt(II) and cadmium(II) are determined in the presence of large excesses of calcium(II) and magnesium(II). The resin was found to be selective for silver(I) and mercury(II) at low pH values and a rapid separation of equal molar amounts of copper(II) and silver(I) was performed. The resin was also found to have an affinity for anionic metal complexes such as iron(III)-tartrate when the resin is in the hydrogen form. A study of the retention of the anions chromium(III)-tartrate and dichromate at various pH values was performed to better understand the anion exchange properties of the resin. Triethylenetetramine resins were also prepared from polystyrene gel to make a resin with higher capacities for copper

Nitrate Enhanced Microbial Cr(VI) Reduction-Final Report

Energy Technology Data Exchange (ETDEWEB)

John F. Stolz

2011-06-15

A major challenge for the bioremediation of radionuclides (i.e., uranium, technetium) and metals (i.e., Cr(VI), Hg) is the co-occurrence of nitrate as it can inhibit metal transformation. Denitrification (nitrate reduction to dinitrogen gas) is considered the most important ecological process. For many metal and metalloid reducing bacteria, however, ammonia is the end product through respiratory nitrate reduction (RNRA). The focus of this work was to determine how RNRA impacts Cr(VI) transformation. The goal was to elucidate the specific mechanism(s) that limits Cr(VI) reduction in the presence of nitrate and to use this information to develop strategies that enhance Cr(VI) reduction (and thus detoxification). Our central hypothesis is that nitrate impacts the biotransformation of metals and metalloids in three ways 1) as a competitive alternative electron acceptor (inhibiting transformation), 2) as a co-metabolite (i.e., concomitant reduction, stimulating transformation), and 3) as an inducer of specific proteins and pathways involved in oxidation/reduction reactions (stimulating transformation). We have identified three model organisms, Geobacter metallireducens (mechanism 1), Sulfurospirillum barnesii, (mechasism 2), and Desulfovibrio desulfuricans (mechanisms 3). Our specific aims were to 1) investigate the role of Cr(VI) concentration on the kinetics of both growth and reduction of nitrate, nitrite, and Cr(VI) in these three organisms; 2) develop a profile of bacterial enzymes involved in nitrate transformation (e.g., oxidoreductases) using a proteomic approach; 3) investigate the function of periplasmic nitrite reductase (Nrf) as a chromate reductase; and 4) develop a strategy to maximize microbial chromium reduction in the presence of nitrate. We found that growth on nitrate by G. metallireducens was inhibited by Cr(VI). Over 240 proteins were identified by LC/MS-MS. Redox active proteins, outer membrane heavy metal efflux proteins, and chemotaxis sensory

Rock Fracture Toughness Study Under Mixed Mode I/III Loading

Science.gov (United States)

Aliha, M. R. M.; Bahmani, A.

2017-07-01

Fracture growth in underground rock structures occurs under complex stress states, which typically include the in- and out-of-plane sliding deformation of jointed rock masses before catastrophic failure. However, the lack of a comprehensive theoretical and experimental fracture toughness study for rocks under contributions of out-of plane deformations (i.e. mode III) is one of the shortcomings of this field. Therefore, in this research the mixed mode I/III fracture toughness of a typical rock material is investigated experimentally by means of a novel cracked disc specimen subjected to bend loading. It was shown that the specimen can provide full combinations of modes I and III and consequently a complete set of mixed mode I/III fracture toughness data were determined for the tested marble rock. By moving from pure mode I towards pure mode III, fracture load was increased; however, the corresponding fracture toughness value became smaller. The obtained experimental fracture toughness results were finally predicted using theoretical and empirical fracture models.

Synthesis and Evaluation of new Polyfunctional Molecules for Group Actinide Extraction

International Nuclear Information System (INIS)

Marie, C.

2009-10-01

The aim of this project is to design new extracting molecules for spent nuclear fuel reprocessing. In order to minimize the long-term residual radiotoxicity of the waste, the GANEX process is an option based on homogeneous recycling of actinides. All actinides (U, Np, Pu, Am, Cm), present in a highly acidic aqueous solution, would be extracted together and separated from fission products (especially from lanthanides) using liquid-liquid extraction. In this context, twenty new bi-topic ligands constituted of a nitrogen poly-aromatic unit functionalized by amide groups were synthesized. Liquid-liquid extraction tests with these ligands dissolved alone in the organic phase show that N, N, N', N'-tetra-alkyl-6, 6''(2, 2':6', 2''-terpyridine)-diamides are able to selectively extract actinides at different oxidation states (Np(V et VI), U(VI), Pu(IV), Am(III), Cm(III)) from an aqueous solution 3M HNO 3 . Nevertheless, actinides(III) are poorly extracted. According to crystallographic structures of complexes with Nd(III) and U(VI) determined by X-rays diffraction, these ligands are penta-dentate. In solution (methanol), complexes stoichiometries (1:1) of Nd(III), U(VI) and Pu(IV) were determined by electro-spray ionization mass spectrometry. Stability constants, evaluated by UV-visible spectrophotometry in MeOH/H 2 O solutions, confirm the selectivity of ligands toward actinides(III) with respect to lanthanides(III). Associate to nuclear magnetic resonance experiments and DFT calculations (Density Functional Theory), a better knowledge of their coordination mode was achieved. (author)

Sistemas de classificações geotécnicas de solos: estudo de caso aplicado à rodovia não pavimentada vcs 346, Viçosa, MG Geotechnical soil classification systems: case study applied to the vcs 346 unpaved road, Viçosa, MG

Directory of Open Access Journals (Sweden)

Taciano Oliveira da Silva

2010-04-01

Full Text Available Este artigo aborda uma contribuição às classificações geotécnicas tradicionais de solos Unified Soil Classification System (USC, Transportation Research Board System (TRB e a Metodologia Miniatura, Compactado, Tropical (MCT para um caso aplicado à rodovia municipal não pavimentada VCS 346, no Município de Viçosa, MG, considerando-se várias amostras deformadas de solos coletadas no subleito da referida via. Os principais objetivos deste estudo residem na contribuição de um banco de dados geotécnicos sobre classificações de solos tropicais, bem como na verificação de possíveis agrupamentos entre os sistemas geotécnicos tradicionais de classificação e a metodologia MCT. O programa de laboratório envolveu a realização dos seguintes ensaios: (i granulometria conjunta; (ii limites de Atterberg (LL e LP; (iii massa específica dos grãos do solo; (iv compactação Mini-MCV; e (v perda de massa do corpo-de-prova por imersão em água. Os resultados possibilitaram verificar que, após a classificação das amostras, vários agrupamentos entre os sistemas de classificações geotécnicas tradicionais coincidiram com aqueles já apresentados na metodologia MCT e, considerando a pedogênese da região de Viçosa, MG, para o grupo NG', houve a contribuição dos grupos SC, SM e CL do Sistema USC e do grupo A-4 do Sistema TRB.This paper addresses a contribution to the traditional geotechnical soil classifications systems USC (Unified Soil Classification and TRB (Transportation Research Board, and the MCT methodology (Miniature, Compacted, Tropical applied to a case study involving the laboratory geotechnical characterization of disturbed samples from the subgrade of the VCS 346 municipal unpaved road, located in Viçosa - MG. The main goals of this study are to contribute to the formation of a database directed to the geotechnical classification of tropical soils as well as to verify possible groupings among the traditional

Classification of mood disorders in DSM-V and DSM-VI.

Science.gov (United States)

Joyce, Peter R

2008-10-01

For any diagnostic system to be clinically useful, and go beyond description, it must provide an understanding that informs about aetiology and/or outcome. DSM-III and DSM-IV have provided reliability; the challenge for DSM-V and DSM-VI will be to provide validity. For DSM-V this will not be achieved. Believers in DSM-III and DSM-IV have impeded progress towards a valid classification system, so DSM-V needs to retain continuity with its predecessors to retain reliability and enhance research, but position itself to inform a valid diagnostic system by DSM-VI. This review examines the features of a diagnostic system and summarizes what is really known about mood disorders. The review also questions whether what are called mood disorders are primarily disorders of mood. Finally, it provides suggestions for DSM-VI.

Cr(Vi) reduction capacity of activated sludge as affected by nitrogen and carbon sources, microbial acclimation and cell multiplication

International Nuclear Information System (INIS)

Ferro Orozco, A.M.; Contreras, E.M.; Zaritzky, N.E.

2010-01-01

The objectives of the present work were: (i) to analyze the capacity of activated sludge to reduce hexavalent chromium using different carbon sources as electron donors in batch reactors, (ii) to determine the relationship between biomass growth and the amount of Cr(VI) reduced considering the effect of the nitrogen to carbon source ratio, and (iii) to determine the effect of the Cr(VI) acclimation stage on the performance of the biological chromium reduction assessing the stability of the Cr(VI) reduction capacity of the activated sludge. The highest specific Cr(VI) removal rate (q Cr ) was attained with cheese whey or lactose as electron donors decreasing in the following order: cheese whey ∼ lactose > glucose > citrate > acetate. Batch assays with different nitrogen to carbon source ratio demonstrated that biological Cr(VI) reduction is associated to the cell multiplication phase; as a result, maximum Cr(VI) removal rates occur when there is no substrate limitation. The biomass can be acclimated to the presence of Cr(VI) and generate new cells that maintain the ability to reduce chromate. Therefore, the activated sludge process could be applied to a continuous Cr(VI) removal process.

A randomized trial comparing monophasic and biphasic waveform shocks for external cardioversion of atrial fibrillation

NARCIS (Netherlands)

Koster, Rudolph W.; Dorian, Paul; Chapman, Fred W.; Schmitt, Paul W.; O'Grady, Sharon G.; Walker, Robert G.

2004-01-01

Background We compared efficacy of and pain felt after biphasic truncated exponential (BTE) and monophasic damped sine (MDS) shocks in patients undergoing external cardioversion of atrial fibrillation (AF). Methods Patients with AF were randomized to BTE or MDS waveform cardioversion. Successive

Complexation of Eu(III), Th(IV) and U(VI) by humic substances

International Nuclear Information System (INIS)

Moulin, V.; Reiller, P.; Dautel, C.; Plancque, G.; Laszak, I.; Moulin, C.

1999-01-01

Complexation of actinides by humic substances has been studied by different techniques depending on the actinide and its oxidation state. For trivalent actinide (using a rare earth element, Eu as an analogue of trivalent actinide), Time-Resolved Laser-Induced Fluorescence (TRLIF) has been retained as a method for direction speciation at low level. By varying pH and physicochemical conditions (absence of carbonate ions) and at fixed ionic strength, it is possible together to identify spectrally and temporally, all the hydroxo and carbonato complexes. This approach has also been retained for U(VI) as a model of hexavalent actinide, for which hydroxo complexes have been characterized by TRLIF (the simple carbonato complexes are not fluorescent). In the case of U(VI), titrations hy humic acids of U(VI) solutions at various pH have allowed to characterize organic complexes formed with U(VI): single complexes (UO 2 HA) and mixed complexes (UO 2 (OH) 3 HA). The impact on U(VI) speciation has then been identified. In the case of Th(IV) as a model of tetravalent actinides, a competitive method has been used to obtain data on the Th-HA system by studying the ternary system silica colloid/HA/Th at constant pH (Schubert method). Apparent interaction constants have been calculated depending on Th hydrolysis constants used. A study of the system Th/HA/silica has a function of pH and for different HA concentrations has shown the strong complexing character of humic acids towards Th in the pH range 4-9. (orig.)

Lower incisor dentoalveolar compensation and symphysis dimensions among Class I and III malocclusion patients with different facial vertical skeletal patterns.

Science.gov (United States)

Molina-Berlanga, Núria; Llopis-Perez, Jaume; Flores-Mir, Carlos; Puigdollers, Andreu

2013-11-01

To compare lower incisor dentoalveolar compensation and mandible symphysis morphology among Class I and Class III malocclusion patients with different facial vertical skeletal patterns. Lower incisor extrusion and inclination, as well as buccal (LA) and lingual (LP) cortex depth, and mandibular symphysis height (LH) were measured in 107 lateral cephalometric x-rays of adult patients without prior orthodontic treatment. In addition, malocclusion type (Class I or III) and facial vertical skeletal pattern were considered. Through a principal component analysis (PCA) related variables were reduced. Simple regression equation and multivariate analyses of variance were also used. Incisor mandibular plane angle (P Class I P  =  .03 and Class III P  =  .01) and a positive correlation with LH (Class I P  =  .01 and Class III P  =  .02) in both groups. Within the Class III group, there was a negative correlation between the mandibular plane and LP (P  =  .02). PCA showed that the tendency toward a long face causes the symphysis to elongate and narrow. In Class III, alveolar narrowing is also found in normal faces. Vertical facial pattern is a significant factor in mandibular symphysis alveolar morphology and lower incisor positioning, both for Class I and Class III patients. Short-faced Class III patients have a widened alveolar bone. However, for long-faced and normal-faced Class III, natural compensation elongates the symphysis and influences lower incisor position.

Antisites in III-V semiconductors: Density functional theory calculations

KAUST Repository

Chroneos, A.

2014-07-14

Density functional based simulation, corrected for finite size effects, is used to investigate systematically the formation of antisite defects in III-V semiconductors (III=Al, Ga, and In and V=P, As, and Sb). Different charge states are modelled as a function of the Fermi level and under different growth conditions. The formation energies of group III antisites (III V q) decrease with increasing covalent radius of the group V atom though not group III radius, whereas group V antisites (V I I I q) show a consistent decrease in formation energies with increase in group III and group V covalent radii. In general, III V q defects dominate under III-rich conditions and V I I I q under V-rich conditions. Comparison with equivalent vacancy formation energy simulations shows that while antisite concentrations are always dominant under stoichiometric conditions, modest variation in growth or doping conditions can lead to a significantly higher concentration of vacancies. © 2014 AIP Publishing LLC.

Influence of Term of Exposure to High-Fat Diet-Induced Obesity on Myocardial Collagen Type I and III

International Nuclear Information System (INIS)

Silva, Danielle Cristina Tomaz da; Lima-Leopoldo, Ana Paula; Leopoldo, André Soares; Campos, Dijon Henrique Salomé de; Nascimento, André Ferreira do; Oliveira, Sílvio Assis Junior de; Padovani, Carlos Roberto; Cicogna, Antonio Carlos

2014-01-01

Obesity is a risk factor for many medical complications; medical research has shown that hemodynamic, morphological and functional abnormalities are correlated with the duration and severity of obesity. Present study determined the influence of term of exposure to high-fat diet-induced obesity on myocardial collagen type I and III. Thirty-day-old male Wistar rats were randomly distributed into two groups: a control (C) group fed a standard rat chow and an obese (Ob) group alternately fed one of four palatable high-fat diets. Each diet was changed daily, and the rats were maintained on their respective diets for 15 (C 15 and Ob 15 ) and 30 (C 30 and Ob 30 ) consecutive weeks. Obesity was determined by adiposity index. The Ob 15 group was similar to the C 15 group regarding the expression of myocardial collagen type I; however, expression in the Ob 30 group was less than C 30 group. The time of exposure to obesity was associated with a reduction in collagen type I in Ob 30 when compared with Ob 15 . Obesity did not affect collagen type III expression. This study showed that the time of exposure to obesity for 30 weeks induced by unsaturated high-fat diet caused a reduction in myocardial collagen type I expression in the obese rats. However, no effect was seen on myocardial collagen type III expression

Brainstem auditory evoked response characteristics in normal-hearing subjects with chronic tinnitus and in non-tinnitus group

Directory of Open Access Journals (Sweden)

Shadman Nemati

2014-06-01

Full Text Available Background and Aim: While most of the people with tinnitus have some degrees of hearing impairment, a small percent of patients admitted to ear, nose and throat clinics or hearing evaluation centers are those who complain of tinnitus despite having normal hearing thresholds. This study was performed to better understanding of the reasons of probable causes of tinnitus and to investigate possible changes in the auditory brainstem function in normal-hearing patients with chronic tinnitus.Methods: In this comparative cross-sectional, descriptive and analytic study, 52 ears (26 with and 26 without tinnitus were examined. Components of the auditory brainstem response (ABR including wave latencies and wave amplitudes were determined in the two groups and analyzed using appropriate statistical methods.Results: The mean differences between the absolute latencies of waves I, III and V was less than 0.1 ms between the two groups that was not statistically significant. Also, the interpeak latency values of waves I-III, III-V and I-V in both groups had no significant difference. Only, the V/I amplitude ratio in the tinnitus group was significantly higher (p=0.04.Conclusion: The changes observed in amplitude of waves, especially in the latter ones, can be considered as an indication of plastic changes in neuronal activity and its possible role in generation of tinnitus in normal-hearing patients.

N-butylamine functionalized graphene oxide for detection of iron(III) by photoluminescence quenching.

Science.gov (United States)

Gholami, Javad; Manteghian, Mehrdad; Badiei, Alireza; Ueda, Hiroshi; Javanbakht, Mehran

2016-02-01

An N-butylamine functionalized graphene oxide nanolayer was synthesized and characterized by ultraviolet (UV)-visible spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Detection of iron(III) based on photoluminescence spectroscopy was investigated. The N-butylamine functionalized graphene oxide was shown to specifically interact with iron (III), compared with other cationic trace elements including potassium (I), sodium (I), calcium (II), chromium (III), zinc (II), cobalt (II), copper (II), magnesium (II), manganese (II), and molybdenum (VI). The quenching effect of iron (III) on the luminescence emission of N-butylamine functionalized graphene oxide layer was used to detect iron (III). The limit of detection (2.8 × 10(-6)  M) and limit of quantitation (2.9 × 10(-5)  M) were obtained under optimal conditions. Copyright © 2015 John Wiley & Sons, Ltd.

Phylogenetic relationships of Salmonella based on rRNA sequences

DEFF Research Database (Denmark)

Christensen, H.; Nordentoft, Steen; Olsen, J.E.

1998-01-01

separated by 16S rRNA analysis and found to be closely related to the Escherichia coli and Shigella complex by both 16S and 23S rRNA analyses. The diphasic serotypes S. enterica subspp. I and VI were separated from the monophasic serotypes subspp. IIIa and IV, including S. bongori, by 23S rRNA sequence...

Chromium(VI) generation in vadose zone soils and alluvial sediments of the southwestern Sacramento Valley, California: A potential source of geogenic Cr(VI) to groundwater

International Nuclear Information System (INIS)

Mills, Christopher T.; Morrison, Jean M.; Goldhaber, Martin B.; Ellefsen, Karl J.

2011-01-01

Highlights: → Southern Sacramento Valley soil and sediment has abundant naturally-occurring Cr(III). → Cr(III) resides mainly in chromite but some is associated with clays and Fe oxides. → Cr(VI) is mostly absent in surface soil but ubiquitous in deeper soil and sediment. → Cr(VI) increased linearly with time during lab soil incubations with no additions. → Cation exchange processes resulted in greater Cr(VI) generation rates. - Abstract: Concentrations of geogenic Cr(VI) in groundwater that exceed the World Health Organization's maximum contaminant level for drinking water (50 μg L -1 ) occur in several locations globally. The major mechanism for mobilization of this Cr(VI) at these sites is the weathering of Cr(III) from ultramafic rocks and its subsequent oxidation on Mn oxides. This process may be occurring in the southern Sacramento Valley of California where Cr(VI) concentrations in groundwater can approach or exceed 50 μg L -1 . To characterize Cr geochemistry in the area, samples from several soil auger cores (approximately 4 m deep) and drill cores (approximately 25 m deep) were analyzed for total concentrations of 44 major, minor and trace elements, Cr associated with labile Mn and Fe oxides, and Cr(VI). Total concentrations of Cr in these samples ranged from 140 to 2220 mg per kg soil. Between 9 and 70 mg per kg soil was released by selective extractions that target Fe oxides, but essentially no Cr was associated with the abundant reactive Mn oxides (up to ∼1000 mg hydroxylamine-reducible Mn per kg soil was present). Both borehole magnetic susceptibility surveys performed at some of the drill core sites and relative differences between Cr released in a 4-acid digestion versus total Cr (lithium metaborate fusion digestion) suggest that the majority of total Cr in the samples is present in refractory chromite minerals transported from ultramafic exposures in the Coast Range Mountains. Chromium(VI) in the samples studied ranged from 0 to 42 �

Chromium(VI) generation in vadose zone soils and alluvial sediments of the southwestern Sacramento Valley, California: A potential source of geogenic Cr(VI) to groundwater

Energy Technology Data Exchange (ETDEWEB)

Mills, Christopher T., E-mail: cmills@usgs.gov [United States Geological Survey, Crustal Geophysics and Geochemistry Science Center, Denver Federal Center, MS 964D, Denver, CO 80225 (United States); Morrison, Jean M.; Goldhaber, Martin B.; Ellefsen, Karl J. [United States Geological Survey, Crustal Geophysics and Geochemistry Science Center, Denver Federal Center, MS 964D, Denver, CO 80225 (United States)

2011-08-15

Highlights: > Southern Sacramento Valley soil and sediment has abundant naturally-occurring Cr(III). > Cr(III) resides mainly in chromite but some is associated with clays and Fe oxides. > Cr(VI) is mostly absent in surface soil but ubiquitous in deeper soil and sediment. > Cr(VI) increased linearly with time during lab soil incubations with no additions. > Cation exchange processes resulted in greater Cr(VI) generation rates. - Abstract: Concentrations of geogenic Cr(VI) in groundwater that exceed the World Health Organization's maximum contaminant level for drinking water (50 {mu}g L{sup -1}) occur in several locations globally. The major mechanism for mobilization of this Cr(VI) at these sites is the weathering of Cr(III) from ultramafic rocks and its subsequent oxidation on Mn oxides. This process may be occurring in the southern Sacramento Valley of California where Cr(VI) concentrations in groundwater can approach or exceed 50 {mu}g L{sup -1}. To characterize Cr geochemistry in the area, samples from several soil auger cores (approximately 4 m deep) and drill cores (approximately 25 m deep) were analyzed for total concentrations of 44 major, minor and trace elements, Cr associated with labile Mn and Fe oxides, and Cr(VI). Total concentrations of Cr in these samples ranged from 140 to 2220 mg per kg soil. Between 9 and 70 mg per kg soil was released by selective extractions that target Fe oxides, but essentially no Cr was associated with the abundant reactive Mn oxides (up to {approx}1000 mg hydroxylamine-reducible Mn per kg soil was present). Both borehole magnetic susceptibility surveys performed at some of the drill core sites and relative differences between Cr released in a 4-acid digestion versus total Cr (lithium metaborate fusion digestion) suggest that the majority of total Cr in the samples is present in refractory chromite minerals transported from ultramafic exposures in the Coast Range Mountains. Chromium(VI) in the samples studied ranged

Antisites in III-V semiconductors: Density functional theory calculations

KAUST Repository

Chroneos, A.; Tahini, Hassan Ali; Schwingenschlö gl, Udo; Grimes, R. W.

2014-01-01

as a function of the Fermi level and under different growth conditions. The formation energies of group III antisites (III V q) decrease with increasing covalent radius of the group V atom though not group III radius, whereas group V antisites (V I I I

Synthesis of graphite intercalation compound of group VI metals and uranium hexafluorides

International Nuclear Information System (INIS)

Fukui, Toshihiro; Hagiwara, Rika; Ema, Keiko; Ito, Yasuhiko

1993-01-01

Systematic investigations were made on the synthesis of graphite intercalation compounds of group VI transition metals (W and Mo) and uranium hexafluorides. The reactions were performed by interacting liquid or gaseous metal hexafluorides with or without elemental fluorine at ambient temperature. The degree of intercalation of these metal fluorides depends on the formation enthalpy of fluorometallate anion from the original metal hexafluoride, as has been found for other intercalation reactions of metal fluorides. (author)

Selective extraction of U(VI), Th(IV), and La(III) from acidic matrix solutions and environmental samples using chemically modified Amberlite XAD-16 resin

Energy Technology Data Exchange (ETDEWEB)

Prabhakaran, D.; Subramanian, M.S. [Department of Chemistry, Indian Institute of Technology, 600 036, Chennai (India)

2004-06-01

A new grafted polymer has been developed by the chemical modification of Amberlite XAD-16 (AXAD-16) polymeric matrix with [(2-dihydroxyarsinoylphenylamino)methyl]phosphonic acid (AXAD-16-AsP). The modified polymer was characterized by a combination of {sup 13}C CPMAS and {sup 31}P solid-state NMR, Fourier transform-NIR-FIR-Raman spectroscopy, CHNPS elemental analysis, and thermogravimetric analysis (TGA). The distribution studies for the extraction of U(VI), Th(IV), and La(III) from acidic solutions were performed using an AXAD-16-AsP-packed chromatographic column. The influences of various physiochemical parameters on analyte recovery were optimized by both static and dynamic methods. Accordingly, even under high acidities (>4 M), good distribution ratio (D) values (10{sup 2}-10{sup 4}) were achieved for all the analytes. Metal ion desorption was effective using 1 mol L{sup -1} (NH{sub 4}){sub 2}CO{sub 3}. From kinetic studies, a time duration of <15 min was sufficient for complete metal ion saturation of the resin phase. The maximum metal sorption capacities were found to be 0.25, 0.13, and 1.49 mmol g{sup -1} for U(VI); 0.47, 0.39, and 1.40 mmol g{sup -1} for Th(IV); and 1.44, 1.48, and 1.12 mmol g{sup -1} for La(III), in the presence of 2 mol L{sup -1} HNO{sub 3}, 2 mol L{sup -1} HCl, and under pH conditions, respectively. The analyte selectivity of the grafted polymer was tested in terms of interfering species tolerance studies. The system showed an enrichment factor of 365, 300, and 270 for U(VI), Th(IV), and La(III), and the limit of analyte detection was in the range of 18-23 ng mL{sup -1}. The practical applicability of the polymer was tested with synthetic nuclear spent fuel and seawater mixtures, natural water, and geological samples. The RSD of the total analytical procedure was within 4.9%, thus confirming the reliability of the developed method. (orig.)

Strengere kapitalkrav i pengeinstitutterne

DEFF Research Database (Denmark)

Rangvid, Jesper

2010-01-01

Artiklen præsenterer estimater over de økonomiske omkostninger ved den finansielle krise vi lige har været igennem. Omkostningerne er meget høje. Kravene om højere egenkapital i banker som Basel III medfører, vil gøre banker sikrere og derved mindske sandsynligheden for fremtidige finansielle...

Experimental Monitoring of Cr(VI) Bio-reduction Using Electrochemical Geophysics

International Nuclear Information System (INIS)

Birsen Canan; Gary R. Olhoeft; William A. Smith

2007-01-01

Many Department of Energy (DOE) sites are contaminated with highly carcinogenic hexavalent chromium (Cr(VI)). In this research, we explore the feasibility of applying complex resistivity to the detection and monitoring of microbially-induced reduction of hexavalent chromium (Cr(VI)) to a less toxic form (Cr(III)). We hope to measure the change in ionic concentration that occurs during this reduction reaction. This form of reduction promises to be an attractive alternative to more expensive remedial treatment methods. The specific goal of this research is to define the minimum and maximum concentration of the chemical and biological compounds in contaminated samples for which the Cr(VI) - Cr(III) reduction processes could be detected via complex resistivity. There are three sets of experiments, each comprised of three sample columns. The first experiment compares three concentrations of Cr(VI) at the same bacterial cell concentration. The second experiment establishes background samples with, and without, Cr(VI) and bacterial cells. The third experiment examines the influence of three different bacterial cell counts on the same concentration of Cr(VI). A polarization relaxation mechanism was observed between 10 and 50 Hz. The polarization mechanism, unfortunately, was not unique to bio-chemically active samples. Spectral analysis of complex resistivity data, however, showed that the frequency where the phase minimum occurred was not constant for bio-chemically active samples throughout the experiment. A significant shifts in phase minima occurred between 10 to 20 Hz from the initiation to completion of Cr(VI) reduction. This phenomena was quantified using the Cole-Cole model and the Marquardt-Levenberg nonlinear least square minimization method. The data suggests that the relaxation time and the time constant of this relaxation are the Cole-Cole parameters most sensitive to changes in biologically-induced reduction of Cr(VI)

Influence of chemical compositions and molecular weights of humic acids on Cr(VI) photo-reduction

Energy Technology Data Exchange (ETDEWEB)

Chen, S.Y.; Huang, S.W. [Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung, 40227 Taiwan, ROC (China); Chiang, P.N. [The Experimental Forest, National Taiwan University, Nantou, 55743 Taiwan, ROC (China); Liu, J.C. [Agricultural Research Institute No. 189, Jhongjheng Rd., Wufong, Taichung County, 41301 Taiwan, ROC (China); Kuan, W.H. [Department of Safety, Health, and Environmental Engineering, Ming Chi University of Technology, Taishan, Taipei, 24301 Taiwan, ROC (China); Huang, J.H. [Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung, 40227 Taiwan, ROC (China); Hung, J.T. [Department of Horticulture, National Taitung Junior College, Taitung, 95045 Taiwan, ROC (China); Tzou, Y.M., E-mail: ymtzou@dragon.nchu.edu.tw [Department of Soil and Environmental Sciences, National Chung Hsing University, Taichung, 40227 Taiwan, ROC (China); Chen, C.C. [Department of Life Science, National Taiwan Normal University, Taipei, 116 Taiwan, ROC (China); Wang, M.K. [Department of Agricultural Chemistry, National Taiwan University, Taipei, 10617 Taiwan, ROC (China)

2011-12-15

Highlights: Black-Right-Pointing-Pointer Low molecular weights (M{sub w}) of HA bear more polar and aromatic C in its structure. Black-Right-Pointing-Pointer The polar sites of HA dominate the photo-reduction of Cr(VI). Black-Right-Pointing-Pointer Low M{sub w} of HA exhibits greater photochemical efficiency for Cr(VI) reduction. Black-Right-Pointing-Pointer Cr(VI) adsorption on HA is indiscernible, particularly on the small M{sub w} of HA. Black-Right-Pointing-Pointer Upon Cr(VI) reduction by HA, most of Cr(III) are released into the solution. - Abstract: Humic acids (HA) strongly affect the fate of trace metals in soils and aquatic environments. One of the remarkable properties of HA is its ability to reduce Cr(VI), an extremely toxic anion. However, it is unclear which HA components are involved in Cr(VI) reduction and possess the photo-induced properties. In this study, an ultrafiltration technique was used to fractionate HAs into four fractions of different nominal molecular weights (M{sub w}): >100, 50-100, 10-50 and <10 kDa. Each HA fraction was characterized by spectroscopic analyses followed by examining Cr(VI) removal on each fraction of HA at pH 1-5. Spectroscopic results indicated that low-M{sub w} HA was enriched with polar and aromatic domains. These polar, including polar C in aliphatic region, and aromatic groups were the major sites for Cr(VI) reduction because they disappeared rapidly upon interaction with Cr(VI). As a result, low M{sub w} of HA exhibited greater efficiency of Cr(VI) reduction. Light induced the rapid transfer of electrons between chromate-phenol/carboxyl ester, or the formation of peroxide radicals or H{sub 2}O{sub 2} through the ready decay of peroxy radicals associated with polar substituents, explained the rapid scavenging of Cr(VI) on polar and aromatic groups of HAs under illumination.

Fremtidens lavenergibyggeri - kan vi gøre som vi plejer?

DEFF Research Database (Denmark)

Larsen, Tine Steen

2011-01-01

Stramninger af kravene til energiforbruget i vores boliger medfører stor fokus på energiberegningen, men erfaringer fra lavenergiboliger opført i dag viser, at vi, for at sikre succes for fremtidens boliger, også skal inddrage dokumentation af indeklimaet og forbedre samarbejdet mellem arkitekter...

Selective recognition by novel calix system: ICT based chemosensor for metal ions

Energy Technology Data Exchange (ETDEWEB)

Bhatt, Keyur D.; Makwana, Bharat A.; Vyas, Disha J.; Mishra, Divya R.; Jain, Vinod K., E-mail: drvkjain@hotmail.com

2014-02-15

A new calix[4]pyrrole derivative bearing four dansyl groups through hydroxyl groups has been synthesized and duly characterized by FT-IR, NMR and ESI-MS. Tetra dansylated calix[4]pyrrole (TDCP) shows selective behavior for U(VI), Th(IV) and Fe(III) ions among all other metal ions, e.g. Li(I), Na(I), K(I), Ca(II), Ni(II), Cd(II), Cu(II), Zn(II), Pb(II), Hg(II) and Ag(I), in the absorption spectra as well as in the emission spectra. The absorption spectra show a bathochromic shift while the emission spectra along with red-shift exhibit quenching for U(VI), Th(IV) and Fe(III) ions. The binding constants, stoichiometry and quantum yields have been determined. The mechanism of quenching by Stern–Vohmer equation has also been discussed. -- highlights: • A new selective turn-off fluorescent sensor i.e. tetra dansylated calix[4]pyrrole (TDCP) was synthesized and characterized. • The sensor shows selective behavior for U(VI), Th(IV) and Fe(III) ions among various other metal ions. • The absorption spectra show a bathochromic shift while the emission spectra along with red-shift exhibit quenching for U(VI), Th(IV) and Fe(III) ions. • The sensor binds metal ions in 1:1 stoichiometry with good binding constant.

Selective recognition by novel calix system: ICT based chemosensor for metal ions

International Nuclear Information System (INIS)

Bhatt, Keyur D.; Makwana, Bharat A.; Vyas, Disha J.; Mishra, Divya R.; Jain, Vinod K.

2014-01-01

A new calix[4]pyrrole derivative bearing four dansyl groups through hydroxyl groups has been synthesized and duly characterized by FT-IR, NMR and ESI-MS. Tetra dansylated calix[4]pyrrole (TDCP) shows selective behavior for U(VI), Th(IV) and Fe(III) ions among all other metal ions, e.g. Li(I), Na(I), K(I), Ca(II), Ni(II), Cd(II), Cu(II), Zn(II), Pb(II), Hg(II) and Ag(I), in the absorption spectra as well as in the emission spectra. The absorption spectra show a bathochromic shift while the emission spectra along with red-shift exhibit quenching for U(VI), Th(IV) and Fe(III) ions. The binding constants, stoichiometry and quantum yields have been determined. The mechanism of quenching by Stern–Vohmer equation has also been discussed. -- highlights: • A new selective turn-off fluorescent sensor i.e. tetra dansylated calix[4]pyrrole (TDCP) was synthesized and characterized. • The sensor shows selective behavior for U(VI), Th(IV) and Fe(III) ions among various other metal ions. • The absorption spectra show a bathochromic shift while the emission spectra along with red-shift exhibit quenching for U(VI), Th(IV) and Fe(III) ions. • The sensor binds metal ions in 1:1 stoichiometry with good binding constant

Can iron oxides remove Cr(VI) from drinking water at sub-ppb levels?

Science.gov (United States)

Kaprara, Efthymia; Simeonidis, Konstantinos; Samaras, Petros; Zouboulis, Anastasios; Mitrakas, Manassis

2013-04-01

Hexavalent chromium [Cr(VI)] has long been recognized as a potential carcinogen via inhalation, in contrast to trivalent chromium [Cr(III)] which is 100 times less toxic and also a necessary nutrient, essential to human glucidic metabolism. Nowadays there is an increasing concern that Cr(VI) is also carcinogenic by the oral route of exposure, while an increased number of publications indicate that Cr(VI) is a common natural pollutant. Hexavalent chromium formation is attributed to natural oxidation of Cr(III) in ultramafic derived soils and ophiolithic rocks. To verify this theory, drinking water samples were collected from targeted areas of Greece e.g. areas in which the geological background is predominated by ultramafic minerals and the water supply depends mainly on groundwater resources. Valuable guide for the samples collection was the geological map of Greece and emphasis was given to regions where the natural occurrence of Cr(VI) is thought to be more possible. A wide range of Cr concentrations (2-100 μg/L) were detected in the areas studied, with most of them ranging below the current limit of 50 μg/L, and the Cr(VI) concentration being more than 90% of the total. Since the Cr(VI) affects significant part of population worldwide, a debate was established concerning the enforcement of stringent regulation, which also demands the drinking water treatment processes re-evaluation in view of Cr(VI) removal at sub-ppb level. In this regard, adsorption has evolved as the front line of defense for chromium removal. The motivation of this work was to investigate the efficiency of iron oxides for the adsorption of Cr(VI) from drinking water and its removal at sub-ppb levels. The adsorbents examined included iron oxy-hydroxides and magnetite prepared using common low cost iron salts. Their effectiveness as Cr(VI) adsorbents was evaluated through the decrease of a Cr(VI) concentration of 100μg/L prepared in NSF water at pH 7. Preliminary batch experiments did not

The Mitochondrial Genome of the Prasinophyte Prasinoderma coloniale Reveals Two Trans-Spliced Group I Introns in the Large Subunit rRNA Gene

Science.gov (United States)

Pombert, Jean-François; Otis, Christian; Turmel, Monique; Lemieux, Claude

2013-01-01

Organelle genes are often interrupted by group I and or group II introns. Splicing of these mobile genetic occurs at the RNA level via serial transesterification steps catalyzed by the introns'own tertiary structures and, sometimes, with the help of external factors. These catalytic ribozymes can be found in cis or trans configuration, and although trans-arrayed group II introns have been known for decades, trans-spliced group I introns have been reported only recently. In the course of sequencing the complete mitochondrial genome of the prasinophyte picoplanktonic green alga Prasinoderma coloniale CCMP 1220 (Prasinococcales, clade VI), we uncovered two additional cases of trans-spliced group I introns. Here, we describe these introns and compare the 54,546 bp-long mitochondrial genome of Prasinoderma with those of four other prasinophytes (clades II, III and V). This comparison underscores the highly variable mitochondrial genome architecture in these ancient chlorophyte lineages. Both Prasinoderma trans-spliced introns reside within the large subunit rRNA gene (rnl) at positions where cis-spliced relatives, often containing homing endonuclease genes, have been found in other organelles. In contrast, all previously reported trans-spliced group I introns occur in different mitochondrial genes (rns or coxI). Each Prasinoderma intron is fragmented into two pieces, forming at the RNA level a secondary structure that resembles those of its cis-spliced counterparts. As observed for other trans-spliced group I introns, the breakpoint of the first intron maps to the variable loop L8, whereas that of the second is uniquely located downstream of P9.1. The breakpoint In each Prasinoderma intron corresponds to the same region where the open reading frame (ORF) occurs when present in cis-spliced orthologs. This correlation between the intron breakpoint and the ORF location in cis-spliced orthologs also holds for other trans-spliced introns; we discuss the possible implications

The mitochondrial genome of the prasinophyte Prasinoderma coloniale reveals two trans-spliced group I introns in the large subunit rRNA gene.

Directory of Open Access Journals (Sweden)

Jean-François Pombert

Full Text Available Organelle genes are often interrupted by group I and or group II introns. Splicing of these mobile genetic occurs at the RNA level via serial transesterification steps catalyzed by the introns'own tertiary structures and, sometimes, with the help of external factors. These catalytic ribozymes can be found in cis or trans configuration, and although trans-arrayed group II introns have been known for decades, trans-spliced group I introns have been reported only recently. In the course of sequencing the complete mitochondrial genome of the prasinophyte picoplanktonic green alga Prasinoderma coloniale CCMP 1220 (Prasinococcales, clade VI, we uncovered two additional cases of trans-spliced group I introns. Here, we describe these introns and compare the 54,546 bp-long mitochondrial genome of Prasinoderma with those of four other prasinophytes (clades II, III and V. This comparison underscores the highly variable mitochondrial genome architecture in these ancient chlorophyte lineages. Both Prasinoderma trans-spliced introns reside within the large subunit rRNA gene (rnl at positions where cis-spliced relatives, often containing homing endonuclease genes, have been found in other organelles. In contrast, all previously reported trans-spliced group I introns occur in different mitochondrial genes (rns or coxI. Each Prasinoderma intron is fragmented into two pieces, forming at the RNA level a secondary structure that resembles those of its cis-spliced counterparts. As observed for other trans-spliced group I introns, the breakpoint of the first intron maps to the variable loop L8, whereas that of the second is uniquely located downstream of P9.1. The breakpoint In each Prasinoderma intron corresponds to the same region where the open reading frame (ORF occurs when present in cis-spliced orthologs. This correlation between the intron breakpoint and the ORF location in cis-spliced orthologs also holds for other trans-spliced introns; we discuss the

Influence of Term of Exposure to High-Fat Diet-Induced Obesity on Myocardial Collagen Type I and III

Energy Technology Data Exchange (ETDEWEB)

Silva, Danielle Cristina Tomaz da [Departamento de Clínica Médica, Faculdade de Medicina de Botucatu, Universidade Estadual Paulista (UNESP), Botucatu, SP (Brazil); Lima-Leopoldo, Ana Paula; Leopoldo, André Soares [Departamento de Esportes, Centro de Educação Física e Desportos da Universidade Federal do Espírito Santo (UFES), Vitória, ES (Brazil); Campos, Dijon Henrique Salomé de; Nascimento, André Ferreira do [Departamento de Clínica Médica, Faculdade de Medicina de Botucatu, Universidade Estadual Paulista (UNESP), Botucatu, SP (Brazil); Oliveira, Sílvio Assis Junior de [Escola de Fisioterapia da Universidade Federal de Mato Grosso do Sul (UFMS), Campo Grande, MS (Brazil); Padovani, Carlos Roberto [Departamento de Bioestatística do Instituto de Ciências Biológicas da Universidade Estadual Paulista (UNESP), Botucatu, SP (Brazil); Cicogna, Antonio Carlos, E-mail: dany.tomaz@gmail.com [Departamento de Clínica Médica, Faculdade de Medicina de Botucatu, Universidade Estadual Paulista (UNESP), Botucatu, SP (Brazil)

2014-02-15

Obesity is a risk factor for many medical complications; medical research has shown that hemodynamic, morphological and functional abnormalities are correlated with the duration and severity of obesity. Present study determined the influence of term of exposure to high-fat diet-induced obesity on myocardial collagen type I and III. Thirty-day-old male Wistar rats were randomly distributed into two groups: a control (C) group fed a standard rat chow and an obese (Ob) group alternately fed one of four palatable high-fat diets. Each diet was changed daily, and the rats were maintained on their respective diets for 15 (C{sub 15} and Ob{sub 15}) and 30 (C{sub 30} and Ob{sub 30}) consecutive weeks. Obesity was determined by adiposity index. The Ob{sub 15} group was similar to the C{sub 15} group regarding the expression of myocardial collagen type I; however, expression in the Ob{sub 30} group was less than C{sub 30} group. The time of exposure to obesity was associated with a reduction in collagen type I in Ob{sub 30} when compared with Ob{sub 15}. Obesity did not affect collagen type III expression. This study showed that the time of exposure to obesity for 30 weeks induced by unsaturated high-fat diet caused a reduction in myocardial collagen type I expression in the obese rats. However, no effect was seen on myocardial collagen type III expression.

Diverse anaerobic Cr(VI) tolerant bacteria from Cr(VI)-contaminated 100H site at Hanford

Science.gov (United States)

Chakraborty, R.; Phan, R.; Lam, S.; Leung, C.; Brodie, E. L.; Hazen, T. C.

2007-12-01

Hexavalent Chromium [Cr(VI)] is a widespread contaminant found in soil, sediment, and ground water. Cr(VI) is more soluble, toxic, carcinogenic, and mutagenic compared to its reduced form Cr(III). In order to stimulate microbially mediated reduction of Cr(VI), a poly-lactate compound HRC was injected into the chromium contaminated aquifers at site 100H at Hanford. Based on the results of the bacterial community composition using high-density DNA microarray analysis of 16S rRNA gene products, we recently investigated the diversity of the dominant anaerobic culturable microbial population present at this site and their role in Cr(VI) reduction. Positive enrichments set up at 30°C using specific defined anaerobic media resulted in the isolation of an iron reducing isolate strain HAF, a sulfate reducing isolate strain HBLS and a nitrate reducing isolate, strain HLN among several others. Preliminary 16S rDNA sequence analysis identifies strain HAF as Geobacter metallireducens, strain HLN as Pseudomonas stutzeri and strain HBLS as a member of Desulfovibrio species. Strain HAF isolated with acetate as the electron donor utilized propionate, glycerol and pyruvate as alternative carbon sources, and reduced metals like Mn(IV) and Cr(VI). Growth was optimal at 37°C, pH of 6.5 and 0% salinity. Strain HLN isolated with lactate as electron donor utilized acetate, glycerol and pyruvate as alternative carbon sources, and reduced metals like Mn(IV) and Cr(VI). Optimal growth was observed at 37°C, at a pH of 7.5 and 0.3% salinity. Anaerobic active washed cell suspension of strain HLN reduced almost 95 micromolar Cr(VI) within 4 hours relative to controls. Further, with 100 micromolar Cr(VI) as the sole electron acceptor, cells of strain HLN grew to cell numbers of 4.05X 107/ml over a period of 24hrs after an initial lag, demonstrating direct enzymatic Cr(VI) reduction by this species. 10mM lactate served as the sole electron donor. These results demonstrate that Cr(VI

Apolipoproteins A-I, B, and C-III and Obesity in Young Adult Cherokee

Directory of Open Access Journals (Sweden)

Wenyu Wang

2017-01-01

Full Text Available Since young adult Cherokee are at increased risk for both diabetes and cardiovascular disease, we assessed association of apolipoproteins (A-I, B, and C-III in non-HDL and HDL with obesity and related risk factors. Obese participants (BMI ≥ 30 aged 20–40 years (n=476 were studied. Metabolically healthy obese (MHO individuals were defined as not having any of four components of the ATP-III metabolic syndrome after exclusion of waist circumference, and obese participants not being MHO were defined as metabolically abnormal obese (MAO. Associations were evaluated by correlation and regression modeling. Obesity measures, blood pressure, insulin resistance, lipids, and apolipoproteins were significantly different between groups except for total cholesterol, LDL-C, and HDL-apoC-III. Apolipoproteins were not correlated with obesity measures with the exception of apoA-I with waist and the waist : height ratio. In a logistic regression model apoA-I and the apoB : apoA-I ratio were significantly selected for identifying those being MHO, and the result (C-statistic = 0.902 indicated that apoA-I and the apoB : apoA-I ratio can be used to identify a subgroup of obese individuals with a significantly less atherogenic lipid and apolipoprotein profile, particularly in obese Cherokee men in whom MHO is more likely.

Performance of TcI/TcVI/TcII Chagas-Flow ATE-IgG2a for universal and genotype-specific serodiagnosis of Trypanosoma cruzi infection.

Directory of Open Access Journals (Sweden)

Glaucia Diniz Alessio

2017-03-01

Full Text Available Distinct Trypanosoma cruzi genotypes have been considered relevant for patient management and therapeutic response of Chagas disease. However, typing strategies for genotype-specific serodiagnosis of Chagas disease are still unavailable and requires standardization for practical application. In this study, an innovative TcI/TcVI/TcII Chagas Flow ATE-IgG2a technique was developed with applicability for universal and genotype-specific diagnosis of T. cruzi infection. For this purpose, the reactivity of serum samples (percentage of positive fluorescent parasites-PPFP obtained from mice chronically infected with TcI/Colombiana, TcVI/CL or TcII/Y strain as well as non-infected controls were determined using amastigote-AMA, trypomastigote-TRYPO and epimastigote-EPI in parallel batches of TcI, TcVI and TcII target antigens. Data demonstrated that "α-TcII-TRYPO/1:500, cut-off/PPFP = 20%" presented an excellent performance for universal diagnosis of T. cruzi infection (AUC = 1.0, Se and Sp = 100%. The combined set of attributes "α-TcI-TRYPO/1:4,000, cut-off/PPFP = 50%", "α-TcII-AMA/1:1,000, cut-off/PPFP = 40%" and "α-TcVI-EPI/1:1,000, cut-off/PPFP = 45%" showed good performance to segregate infections with TcI/Colombiana, TcVI/CL or TcII/Y strain. Overall, hosts infected with TcI/Colombiana and TcII/Y strains displayed opposite patterns of reactivity with "α-TcI TRYPO" and "α-TcII AMA". Hosts infected with TcVI/CL strain showed a typical interweaved distribution pattern. The method presented a good performance for genotype-specific diagnosis, with global accuracy of 69% when the population/prototype scenario include TcI, TcVI and TcII infections and 94% when comprise only TcI and TcII infections. This study also proposes a receiver operating reactivity panel, providing a feasible tool to classify serum samples from hosts infected with distinct T. cruzi genotypes, supporting the potential of this method for universal and genotype-specific diagnosis

On the passivation mechanism of Fe{sub 3}O{sub 4} nanoparticles during Cr(VI) removal from water: A XAFS study

Energy Technology Data Exchange (ETDEWEB)

Pinakidou, F., E-mail: fpina@physics.auth.gr [Aristotle University of Thessaloniki, Department of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece); Katsikini, M. [Aristotle University of Thessaloniki, School of Physics, Section of Solid State Physics, 54124 Thessaloniki (Greece); Simeonidis, K.; Kaprara, E. [Aristotle University of Thessaloniki, Department of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece); Paloura, E.C. [Aristotle University of Thessaloniki, School of Physics, Section of Solid State Physics, 54124 Thessaloniki (Greece); Mitrakas, M. [Aristotle University of Thessaloniki, Department of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece)

2016-01-01

Graphical abstract: - Highlights: • Presence of Fe(II) even after high Cr-loading. • The vacancies in the γ-Fe{sub 2}O{sub 3} layer formed offer sites for Cr(III) sorption. • Cr(III) sorbs into the vacancies and Cr(VI) forms outer sphere complexes. • Increasing surface Cr(III) loading changes the polymerization of the Fe–O–Fe chains. • Cr(III) sorption modifies Fe{sub 3}O{sub 4} structure obstructing further Cr(VI) removal. - Abstract: X-Ray Absorption Spectroscopies (XAFS) are employed in order to gather a thorough insight on the uptake mechanism of Cr(VI) by Fe{sub 3}O{sub 4} nanoparticles under water treatment conditions. The XANES measurements identify that the reducing potential of Fe{sub 3}O{sub 4} activates the precipitation of Cr(VI) in the form of insoluble and non-toxic Cr(III). However, electron donation from Fe(II) is responsible for its gradual consumption, resulting in the presence of a surface maghemite layer and the formation of structural vacancies. EXAFS analysis reveal that adsorption of Cr(III)-oxyanions occurs on sorption sites provided by the vacancies in the maghemite layer, where Cr(III) is involved in a bidentate binuclear ({sup 2}E) geometry with Fe-octahedra while it also forms monodentate ({sup 1}V) complexes with the Fe(III)O{sub 4} tetrahedra. The surface maghemitization along with the reduced Cr(III) adsorption into the vacancies, tracks the degree of Cr-reduction, since this surface structural modifications hinder Cr(VI) access to the Fe(II) ions of the magnetite nanoparticles. Thus, high surface coverage leads to the passivation of the reduction ability since physisorbed Cr(VI) is also detected through the formation of outer sphere complexes.

Non-enzymatic U(VI) interactions with biogenic mackinawite

Science.gov (United States)

Veeramani, H.; Qafoku, N. P.; Kukkadapu, R. K.; Murayama, M.; Hochella, M. F.

2011-12-01

Reductive immobilization of hexavalent uranium [U(VI)] by stimulation of dissimilatory metal and/or sulfate reducing bacteria (DMRB or DSRB) has been extensively researched as a remediation strategy for subsurface U(VI) contamination. These bacteria derive energy by reducing oxidized metals as terminal electron acceptors, often utilizing organic substrates as electron donors. Thus, when evaluating the potential for in-situ uranium remediation in heterogeneous subsurface media, it is important to understand how the presence of alternative electron acceptors such as Fe(III) and sulfate affect U(VI) remediation and the long term behavior and reactivity of reduced uranium. Iron, an abundant subsurface element, represents a substantial sink for electrons from DMRB, and the reduction of Fe(III) leads to the formation of dissolved Fe(II) or to reactive biogenic Fe(II)- and mixed Fe(II)/Fe(III)- mineral phases. Consequently, abiotic U(VI) reduction by reactive forms of biogenic Fe(II) minerals could be a potentially important process for uranium immobilization. In our study, the DMRB Shewanella putrefaciens CN32 was used to synthesize a biogenic Fe(II)-bearing sulfide mineral: mackinawite, that has been characterized by XRD, SEM, HRTEM and Mössbauer spectroscopy. Batch experiments involving treated biogenic mackinawite and uranium (50:1 molar ratio) were carried out at room temperature under strict anoxic conditions. Following complete removal of uranium from solution, the biogenic mackinawite was analyzed by a suite of analytical techniques including XAS, HRTEM and Mössbauer spectroscopy to determine the speciation of uranium and investigate concomitant Fe(II)-phase transformation. Determining the speciation of uranium is critical to success of a remediation strategy. The present work elucidates non-enzymatic/abiotic molecular scale redox interactions between biogenic mackinawite and uranium.

Remediation of Cr(VI) contaminated soil using long-duration sodium thiosulfate supported by micro–nano networks

International Nuclear Information System (INIS)

He, Lulu; Wang, Min; Zhang, Guilong; Qiu, Guannan; Cai, Dongqing; Wu, Zhengyan; Zhang, Xin

2015-01-01

Highlights: • This work aims to develop a long-duration remediation agent (LRA). • LRA was obtained using Na 2 S 2 O 3 supported by attapulgite (ATP) micro–nano networks. • ATP micro–nano networks was induced by high-energy electron beam irradiation. • LRA can effectively control the migration of Cr(VI) and reducing Cr(VI) to Cr(III). • LRA displayed high performance on the remediation of heavy metal contaminated soil. - Abstract: In this work, a long-duration remediation agent (LRA) on hexavalent chromium (Cr(VI)) was developed using sodium thiosulfate (ST) supported by attapulgite (ATP) micro–nano networks induced through high-energy electron beam (HEEB) irradiation. The ATP networks could effectively reduce the leaching amount of Cr(VI) in soil. More importantly, the ATP networks could significantly control the leaching behavior of ST, and then prolong the duration and increase the reduction efficiency of ST on Cr(VI). As a result, LRA displayed high performance on controlling the migration of Cr(VI) and reducing Cr(VI) to Cr(III). Additionally, pot experiment indicated that LRA could effectively decrease the absorbed amount of Cr(VI) in corn, and reduce the inhibition effect of Cr(VI) on the growth of corn. Therefore, this work could provide a facile approach to remediate the Cr(VI)-contaminated soil and lower the harmful effect of Cr(VI) on crop

Remediation of Cr(VI) contaminated soil using long-duration sodium thiosulfate supported by micro–nano networks

Energy Technology Data Exchange (ETDEWEB)

He, Lulu [School of Life Sciences, Anhui Agricultural University, Hefei 230036 (China); Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Wang, Min; Zhang, Guilong [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Bioenergy Forest Research Center of State Forestry Administration, Hefei 230031 (China); Qiu, Guannan [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Cai, Dongqing, E-mail: dqcai@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Bioenergy Forest Research Center of State Forestry Administration, Hefei 230031 (China); Wu, Zhengyan, E-mail: zywu@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Bioenergy Forest Research Center of State Forestry Administration, Hefei 230031 (China); Zhang, Xin, E-mail: xinzhang@ahau.edu.cn [School of Life Sciences, Anhui Agricultural University, Hefei 230036 (China)

2015-08-30

Highlights: • This work aims to develop a long-duration remediation agent (LRA). • LRA was obtained using Na{sub 2}S{sub 2}O{sub 3} supported by attapulgite (ATP) micro–nano networks. • ATP micro–nano networks was induced by high-energy electron beam irradiation. • LRA can effectively control the migration of Cr(VI) and reducing Cr(VI) to Cr(III). • LRA displayed high performance on the remediation of heavy metal contaminated soil. - Abstract: In this work, a long-duration remediation agent (LRA) on hexavalent chromium (Cr(VI)) was developed using sodium thiosulfate (ST) supported by attapulgite (ATP) micro–nano networks induced through high-energy electron beam (HEEB) irradiation. The ATP networks could effectively reduce the leaching amount of Cr(VI) in soil. More importantly, the ATP networks could significantly control the leaching behavior of ST, and then prolong the duration and increase the reduction efficiency of ST on Cr(VI). As a result, LRA displayed high performance on controlling the migration of Cr(VI) and reducing Cr(VI) to Cr(III). Additionally, pot experiment indicated that LRA could effectively decrease the absorbed amount of Cr(VI) in corn, and reduce the inhibition effect of Cr(VI) on the growth of corn. Therefore, this work could provide a facile approach to remediate the Cr(VI)-contaminated soil and lower the harmful effect of Cr(VI) on crop.

Methods for improved growth of group III nitride buffer layers

Science.gov (United States)

Melnik, Yurity; Chen, Lu; Kojiri, Hidehiro

2014-07-15

Methods are disclosed for growing high crystal quality group III-nitride epitaxial layers with advanced multiple buffer layer techniques. In an embodiment, a method includes forming group III-nitride buffer layers that contain aluminum on suitable substrate in a processing chamber of a hydride vapor phase epitaxy processing system. A hydrogen halide or halogen gas is flowing into the growth zone during deposition of buffer layers to suppress homogeneous particle formation. Some combinations of low temperature buffers that contain aluminum (e.g., AlN, AlGaN) and high temperature buffers that contain aluminum (e.g., AlN, AlGaN) may be used to improve crystal quality and morphology of subsequently grown group III-nitride epitaxial layers. The buffer may be deposited on the substrate, or on the surface of another buffer. The additional buffer layers may be added as interlayers in group III-nitride layers (e.g., GaN, AlGaN, AlN).

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

Science.gov (United States)

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.

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

Science.gov (United States)

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

2014-01-01

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

Sn(II) oxy-hydroxides as potential adsorbents for Cr(VI)-uptake from drinking water: An X-ray absorption study

International Nuclear Information System (INIS)

Pinakidou, Fani; Kaprara, Efthimia; Katsikini, Maria; Paloura, Eleni C.; Simeonidis, Konstantinos; Mitrakas, Manassis

2016-01-01

The feasibility of implementing a Sn(II) oxy-hydroxide (Sn_6O_4(OH)_4) for the reduction and adsorption of Cr(VI) in drinking water treatment was investigated using XAFS spectroscopies at the Cr-K-edge. The analysis of the Cr-K-edge XANES and EXAFS spectra verified the effective use of Sn_6O_4(OH)_4 for successful Cr(VI) removal. Adsorption isotherms, as well as dynamic Rapid Small Scale Test (RSSCT) in NSF water matrix showed that Sn_6O_4(OH)_4 can decrease Cr(VI) concentration below the upcoming regulation limit of 10 μg/L for drinking water. Moreover, an uptake capacity of 7.2 μg/mg at breakthrough concentration of 10 μg/L was estimated from the RSSCT, while the residual Cr(VI) concentration ranged at sub-ppb level for a significant period of the experiment. Furthermore, no evidence for the formation of Cr(OH)_3 precipitates was found. On the contrary, Cr(III)-oxyanions were chemisorbed onto SnO_2, which was formed after Sn(II)-oxidation during Cr(VI)-reduction. Nevertheless, changes in the type of Cr(III)-inner sphere complexes were observed after increasing surface coverage: Cr(III)-oxyanions preferentially sorb in a geometry which combines both bidentate binuclear ("2C) and monodentate ("1V) geometries, at the expense of the present bidentate mononuclear ("2E) contributions. On the other hand, the pH during sorption does not affect the adsorption mechanism of Cr(III)-species. The implementation of Sn_6O_4(OH)_4 in water treatment technology combines the advantage of rapidly reducing a large amount of Cr(VI) due to donation of two electrons by Sn(II) and also the strong chemisorption of Cr(III) in a combination of the "2C and "1V configurations, which enhances the safe disposal of spent adsorbents. - Highlights: • Effective Cr(VI) removal from drinking water by Sn_6O_4(OH)_4 • Sn_6O_4(OH)_4 transformation to SnO_2 after Cr(VI) reduction to Cr(III) • Strong Cr(III) sorption onto SnO_2 by formation of inner sphere complexes • Cr(III) sorption

Galanin-immunoreactivity identifies a distinct population of inhibitory interneurons in laminae I-III of the rat spinal cord

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Watanabe Masahiko

2011-05-01

Full Text Available Abstract Background Inhibitory interneurons constitute 30-40% of neurons in laminae I-III and have an important anti-nociceptive role. However, because of the difficulty in classifying them we know little about their organisation. Previous studies have identified 3 non-overlapping groups of inhibitory interneuron, which contain neuropeptide Y (NPY, neuronal nitric oxide synthase (nNOS or parvalbumin, and have shown that these differ in postsynaptic targets. Some inhibitory interneurons contain galanin and the first aim of this study was to determine whether these form a different population from those containing NPY, nNOS or parvalbumin. We also estimated the proportion of neurons and GABAergic axons that contain galanin in laminae I-III. Results Galanin cells were concentrated in laminae I-IIo, with few in laminae IIi-III. Galanin showed minimal co-localisation with NPY, nNOS or parvalbumin in laminae I-II, but most galanin-containing cells in lamina III were nNOS-positive. Galanin cells constituted ~7%, 3% and 2% of all neurons in laminae I, II and III, and we estimate that this corresponds to 26%, 10% and 5% of the GABAergic neurons in these laminae. However, galanin was only found in ~6% of GABAergic boutons in laminae I-IIo, and ~1% of those in laminae IIi-III. Conclusions These results show that galanin, NPY, nNOS and parvalbumin can be used to define four distinct neurochemical populations of inhibitory interneurons. Together with results of a recent study, they suggest that the galanin and NPY populations account for around half of the inhibitory interneurons in lamina I and a quarter of those in lamina II.

Reduction of ferrate(VI) and oxidation of cyanate in a Fe(VI)-TiO2-UV-NCO- system.

Science.gov (United States)

Winkelmann, Kurt; Sharma, Virender K; Lin, Yekaterina; Shreve, Katherine A; Winkelmann, Catherine; Hoisington, Laura J; Yngard, Ria A

2008-08-01

The aqueous photocatalytic degradation of cyanate (NCO(-)), which is a long-lived neurotoxin formed during the remediation of cyanide in industrial waste streams, was studied in the ferrate(VI)-UV-TiO2-NCO(-) system. Kinetics measurements of the photocatalytic reduction of ferrate(VI) were carried out as a function of [NCO(-)], [ferrate(VI)], [O(2)], light intensity (I(o)), and amount of TiO2 in suspensions at pH 9.0. The photocatalytic reduction rate of ferrate(VI) in the studied system can be expressed as -d[Fe(VI)]/dt=kI(o)(0.5) [NCO(-)] [TiO2]. The rate of photocatalytic oxidation of cyanate with ferrate(VI) was greater than the rate in the analogous system without ferrate(VI). The possibility of involvement of reactive ferrate(V) species for this enhancement was determined by studying the reactivity of ferrate(V) with NCO(-) in a homogeneous solution using a premix pulse radiolysis technique. The rate constant for the reaction of ferrate(V) and NCO(-) in alkaline medium was estimated to be (9.60+/-0.07) x 10(2) M(-1) s(-1), which is much slower than the ferrate(VI) self-decomposition reaction (k approximately 10(7) M(-1) s(-1)). An analysis of the kinetic data in the Fe(VI)-UV-TiO2-NCO(-) system suggests that ferrate(V) is not directly participating in the oxidation of cyanate. Possible reactions in the system are presented to explain results of ferrate(VI) reduction and oxidation of cyanate.

Age and gender-related differences in mitral cells of olfactory bulb

International Nuclear Information System (INIS)

Haq, I.H.; Tahir, M.

2008-01-01

To investigate the age and gender-related differences in mitral cells of the human cadaveric olfactory bulbs. Sixty olfactory bulbs, 30 each from male and female (age 20-76 years) human cadavers divided into six groups of age and gender-wise were collected from the mortuary of the King Edward Medical University, Lahore. Mitral cells were counted and their diameter was calculated from 10 micro m thick cresyl violet stained histological sections. Statistical analysis was done using ANOVA for age-related differences and independent t-test for gender-related differences. There was significant reduction in the number of mitral cells and diameter of their nuclei with age. There was significant decrease in the number of mitral cells in males, between groups I and II (p < 0.001); II and III (p < 0.001); and I and III (p < 0.001); statistically significant decrease also occurred in females, between groups IV and V (p < 0.001); V and VI (p < 0.001); and IV and VI (p < 0.001). In most cases, the distance between individual mitral cells was seen to be much greater than in younger group. In group VI, few mitral cells were observed in the cell layer. There was also significant decrease in the diameter of mitral cell nuclei in males, between groups I and III (p < 0.001); and II and III (p < 0.010); in females, between groups IV and VI (p < 0.001); and V and VI (p < 0.001). No gender-related differences were observed. The number of mitral cells and diameter of their nuclei decreased with advancing age. (author)

Catalytic role of Cu(II) in the reduction of Cr(VI) by citric acid under an irradiation of simulated solar light.

Science.gov (United States)

Li, Ying; Chen, Cheng; Zhang, Jing; Lan, Yeqing

2015-05-01

The catalytic role of Cu(II) in the reduction of Cr(VI) by citric acid with simulated solar light was investigated. The results demonstrated that Cu(II) could significantly accelerate Cr(VI) reduction and the reaction obeyed to pseudo zero-order kinetics with respect to Cr(VI). The removal of Cr(VI) was related to the initial concentrations of Cu(II), citric acid, and the types of organic acids. The optimal removal of Cr(VI) was achieved at pH 4, and the rates of Cu(II) photocatalytic reduction of Cr(VI) by organic acids were in the order: tartaric acid (two α-OH groups, two -COOH groups)>citric acid (one α-OH group, three -COOH groups)>malic acid (one α-OH group, two -COOH groups)>lactic acid (one α-OH group, one -COOH group)≫succinic acid (two -COOH groups), suggesting that the number of α-OH was the key factor for the reaction, followed by the number of -COOH. The formation of Cu(II)-citric acid complex could generate Cu(I) and radicals through a pathway of metal-ligand-electron transfer, promoting the reduction of Cr(VI). This study is helpful to fully understanding the conversion of Cr(VI) in the existence of both organic acids and Cu(II) with solar light in aquatic environments. Copyright © 2015 Elsevier Ltd. All rights reserved.

The new concept of hyphenated analytical system: Simultaneous determination of inorganic arsenic(III), arsenic(V), selenium(IV) and selenium(VI) by high performance liquid chromatography-hydride generation-(fast sequential) atomic absorption spectrometry during single analysis

International Nuclear Information System (INIS)

Niedzielski, P.

2005-01-01

The paper presents a new conception of determination of inorganic speciation forms of arsenic: As(III) and As(V) as well selenium Se(IV) and Se(VI) by means of the high performance liquid chromatography hyphenated with a detection by the atomic absorption spectrometry with hydride generation (HPLC-HG-AAS). The application of optimization procedure conditions of chromatographic separation of arsenic and selenium speciation forms (using anion-exchange Supelco LC-SAX1 column and phosphate buffer at pH 5.40 as a mobile phase) as well as the use of the atomic absorption spectrometry as a detector, which enables work in fast sequential mode, allowed to develop original detection methodology of simultaneous determination of arsenic As(III), As(V) and selenium Se(IV) and Se(VI) speciation forms within a 220 s single analysis. The obtained detection limits were 7.8 ng mL -1 for As(III); 12.0 ng mL -1 for As(V); 2.4 ng mL -1 for Se(IV) and 18.6 ng mL -1 for Se(VI) and precision 10.5%, 12.1%, 14.2% and 17.3%, respectively, for 100 ng mL -1 . The described method was used for ground water analysis

LINAG phase I. A technical report, Version: 1.3

International Nuclear Information System (INIS)

Mittig, Wolfgang

2002-01-01

. General remarks; II.2. Production of accelerated ISOL - RIBs from fission and comparison with photoinduced fission; III. High intensity multi-charge ion sources for LINAG I; III.1. Constraints; III.2. Multi-charged ion sources; IV. The linear accelerator; IV.1. General layout of the linear accelerator; IV.2. Source and low energy beam transport line; IV.3. The RFQ injector; IV.4. The superconducting linear accelerator; IV.5. Layout of the driver; IV.6. Review of the driver cost evaluation; V. The target and ion source; V.1. The production and fission fragments; V.1.1. The rotating target/converter; V.1.2. The target and ion source production system; V.1.3. Production rates; V.2. Radioprotection and target handling; VI. Security and radioprotection; VI.1.1. Ion source; VI.1.2.The RFQ; VI.1.3. The liner accelerator; VI.2.1. Ion source; VI.2.2. RFQ; VI.2.3. LINAC; VI.2.4. The high energy beam transport line; VI.2.5. Beam accidents; VI.2.6. Shielding for the target/ion - source; VI.2.7. The authorization procedures; VII. Siting, post-acceleration and coupling to experimental areas; VII.1. Post acceleration option; VII.1.1. Post acceleration in using the CIME cyclotron; VII.1.2. Re-injection of the CIME beams into CSS2; VII.1.3. Post acceleration with C0 + CSS1 + CSS2; VIII. Possible links between LINAG and EURISOL; VIII.1. Background to EURISOL; VIII.2. Synergies; IX. Summary of costs and general schedule; X. Conclusion

Type I and III procollagen propeptides in growth hormone-deficient patients

DEFF Research Database (Denmark)

Jensen, L T; Jørgensen, J O; Risteli, J

1991-01-01

The effect of increasing doses of growth hormone on collagen synthesis in GH-treated GH-deficient patients was determined in a short-term study. The synthesis of type I and III collagen was estimated by measurements of the carboxyterminal propeptide of type I procollagen and the aminoterminal...... propeptide of type III procollagen. Type I collagen is mainly found in bone and type III collagen in loose connective tissue. We observed a GH dose dependency of both procollagen propeptides. Serum type I procollagen propeptide was significantly higher following GH doses of 4 and 6 IU/day for 14 days...... procollagen propeptide increased twice as much as type I procollagen propeptide, by 47 vs 25%, at a GH dose of 6 IU/day compared with 2 IU/day. The differences between the effects on type I and type III collagen may reflect differences in secretion or turn-over rate of collagen in bone and loose connective...

Bringing part of the lab to the field: On-site chromium speciation in seawater by electrodeposition of Cr(III)/Cr(VI) on portable coiled-filament assemblies and measurement in the lab by electrothermal, near-torch vaporization sample introduction and inductively coupled plasma-atomic emission spectrometry

Science.gov (United States)

Badiei, Hamid R.; McEnaney, Jennifer; Karanassios, Vassili

2012-12-01

A field-deployable electrochemical approach to preconcentration, matrix clean up and selective electrodeposition of Cr(III) and Cr(III) + Cr(VI) in seawater is described. Using portable, battery-operated electrochemical instrumentation, Cr species in seawater were electrodeposited in the field on portable coiled-filament assemblies made from Re. Assemblies with dried residues of Cr(III) or Cr(III) + Cr(VI) on them were transported to the lab for concentration determination by electrothermal, near-torch vaporization (NTV) sample introduction and inductively coupled plasma-atomic emission spectrometry (ICP-AES). Electrodeposition offers selective species deposition, preconcentration and matrix clean up from seawater samples. For selective deposition, free Cr(VI) was electrodeposited at - 0.3 V and Cr(III) + Cr(VI) at - 1.6 V (both vs Ag/AgCl). Interestingly, at 0 V (vs Ag/AgCl) and in the absence of an electrodeposition potential only Cr(VI) was spontaneously and selectively adsorbed on the coil and reasons for this are given. Due to preconcentration afforded by electrodeposition, the detection limits obtained after a 60 s electrodeposition at the voltages stated above using buffered (pH = 4.7) artificial seawater spiked with either Cr(III) or Cr(VI) were 20 pg/mL for Cr(III) and 10 pg/mL for Cr(VI). For comparison, the detection limit for Cr obtained by pipetting directly on the coil 5 μL of diluted standard solution was 500 pg/mL, thus it was concluded that electrodeposition offered 40 to 60 fold improvements. Matrix clean up is required due to the high salt content of seawater and this was addressed by simply rinsing the coil with 18.2 MΩ water without any loss of Cr species. Reasons for this are provided. The method was validated in the lab using buffered artificial seawater and it was used in the field for the first time by sampling seawater, buffering it and immediately electrodepositing Cr species on portable assemblies on-site. Electrodeposition in the

Elucidating the mechanism of Cr(VI) formation upon the interaction with metal oxides during coal oxy-fuel combustion.

Science.gov (United States)

Chen, Juan; Jiao, Facun; Zhang, Lian; Yao, Hong; Ninomiya, Yoshihiko

2013-10-15

The thermodynamics underpinning the interaction of Cr-bearing species with basic metal oxides, i.e. K2O, Fe2O3, MgO and CaO, during the air and oxy-fuel combustion of coal have been examined. The synchrotron-based X-ray adsorption near-edge spectroscopy (XANES) was used for Cr speciation. For the oxides tested, Cr(VI) formation is dominated by the reduction potential of the metals. The oxides of Ca(2+) with high reduction potential favored the oxidation of Cr(III), same for K(+). The other two basic metals, Fe2O3 and MgO with lower reduction potentials reacted with Cr(III) to form the corresponding chromites at the temperatures above 600°C. Coal combustion experiments in drop-tube furnace have confirmed the rapid capture of Cr vapors, either trivalent or hexavalent, by CaO into solid ash. The existence of HCl in flue gas favored the vaporization of Cr as CrO2Cl2, which was in turn captured by CaO into chromate. Both Fe2O3 and MgO exhibited less capability on scavenging the Cr(VI) vapor. Particularly, MgO alone exhibited a low capability for capturing the vaporized Cr(III) vapors. However, its co-existence with CaO in the furnace inhibited the Cr(VI) formation. This is beneficial for minimizing the toxicity of Cr in the coal combustion-derived fly ash. Copyright © 2013 Elsevier B.V. All rights reserved.

Time-dependent uptake, distribution and biotransformation of chromium(VI) in individual and bulk human lung cells : application of synchrotron radiation techniques

International Nuclear Information System (INIS)

Harris, H. H.; Levina, A.; Dillon, C. T.; Mulyani, I.; Lai, B.; Cai, Z.; Lay, P.

2005-03-01

Chromium(VI) is a human carcinogen, primarily affecting the respiratory tract probably via active transport into cells, followed by the reduction to Cr(III) with the formation of DNA-damaging intermediates. Distribution of Cr and endogenous elements within A549 human lung adenocarcinoma epithelial cells, following treatment with Cr(VI) (100 (micro)M, 20 min or 4 h) were studied by synchrotron-radiation-induced X-ray emission (SRIXE) of single freeze-dried cells. After the 20-min treatment, Cr was confined to a small area of the cytoplasm and strongly co-localized with S, Cl, K, and Ca. After the 4-h treatment, Cr was distributed throughout the cell, with higher concentrations in the nucleus and the cytoplasmic membrane. This time-dependence corresponded to ∼100% or 0% clonogenic survival of the cells following the 20-min or 4-h treatments, respectively, and could potentially be explained by a new cellular protective mechanism. Such processes may also be important in reducing the potential hazards of Cr(III) dietary supplements, for which there is emerging evidence that they exert their anti-diabetic effects via biological oxidation to Cr(VI). The predominance of Cr(III) was confirmed by micro-XANES spectroscopy of intracellular Cr hotspots. X-ray absorption spectroscopy (XANES and EXAFS, using freeze-dried cells after the 0-4-h treatments) was used to gain insight into the chemical structures of Cr(III) complexes formed during the intracellular reduction of Cr(VI). The polynuclear nature of such complexes (probably with a combination of carboxylato and hydroxo bridging groups and O-donor atoms of small peptides or proteins) was established by XAFS data analyses

Simultaneous Cr(VI) bio-reduction and methane production by anaerobic granular sludge.

Science.gov (United States)

Hu, Qian; Sun, Jiaji; Sun, Dezhi; Tian, Lan; Ji, Yanan; Qiu, Bin

2018-08-01

Wastewater containing toxic hexavalent chromium (Cr(VI)) were treated with well-organized anaerobic granular sludge in this study. Results showed that the anaerobic granular sludge rapidly removed Cr(VI), and 2000 µg·L -1 Cr(VI) was completely eliminated within 6 min, which was much faster than the reported duration of removal by reported artificial materials. Sucrose added as a carbon source acted as an initial electron donor to reduce Cr(VI) to Cr(III). This process was considered as the main mechanism of Cr(VI) removal. Methane production by anaerobic granular sludge was improved by the addition of Cr(VI) at a concentration lower than 500 µg·L -1 . Anaerobic granular sludge had a well-organized structure, which presented good resistance against toxic Cr(VI). Trichoccus accelerated the degradation of organic substances to generate acetates with a low Cr(VI) concentration, thereby enhancing methane production by acetotrophic methanogens. Copyright © 2018 Elsevier Ltd. All rights reserved.

Reduction of trace quantities of chromium(VI by strong acids

Directory of Open Access Journals (Sweden)

Pezzin Sérgio H

2004-01-01

Full Text Available The chemical behavior of Cr(VI at low concentrations (10-4 to 10-7 mol L-1 in several strong acids was studied using high specific activity 51Cr(VI as a tracer. The speciation of the products from these systems was carried out by ion exchange chromatography with stepwise elution. The results show that trace quantities of Cr(VI, monitored by means of radiochromium (51Cr, are reduced in the presence of mineral acids such as perchloric, hydrochloric, hydrofluoric, sulfuric, nitric and trifluoromethanesulfonic acids, even in the absence of conventional reducing agents, producing different measureable Cr(III species, depending on the acid anion. Detailed studies of the reduction of low concentrations of Cr(VI with nitric acid have shown that the relative rate of reduction increases as the concentration of the acid increases or as the concentration of the Cr(VI decreases.

The Position of Hyoici Bone in Skeletal Class I, II and III Patients

Directory of Open Access Journals (Sweden)

Ravanmehr H

2000-06-01

Full Text Available In this investigation, the position of hyoid bone was compared in three skeletal groups of class I, II and III. The study was based on evaluating 77 lateral cephalometric radiographs, 40 girls and 37 boys, which were divided into 3 groups. Group 1, 2, and 3 consist of 26, 25, and 26 radiographs. 19 cephalometric landmarks and 10 planes were used in order to tracing the radiographs. In all patients, 9 skeletal and 4 cervical vertebrae parameters were measured to determine the hyoid bone. These parameters were compared between three skeletal groups regardless of sex and then, in another statistical analysis, parameters were compared based on patients sex. Statistical analysis showed that in class III patients, the hyoid bone was positioned more anteriorly than two other groups. Also in this group, the hyoid bone had less inclination and it was more horizontal in relation to mandibular plane. In skeletal class II patients this bone was positioned more superiorly than two other groups. Due to these findings it can be concluded that perimandibular muscles and bones could affect the growth of mandible. In addition, comparison of the parameters between two sexes revealed that the hyoid bone was positioned more anteriorly and inferiorly in boys. Also it was shown that in the girls, the position of hyoid bone was closer to the position of this bone in skeletal class I patients.

Polyethylenimine-modified fungal biomass as a high-capacity biosorbent for Cr(VI) anions: sorption capacity and uptake mechanisms.

Science.gov (United States)

Deng, Shubo; Ting, Yen Peng

2005-11-01

Heavy metal pollution in the aqueous environment is a problem of global concern. Biosorption has been considered as a promising technology for the removal of low levels of toxic metals from industrial effluents and natural waters. A modified fungal biomass of Penicillium chrysogenum with positive surface charges was prepared by grafting polyethylenimine (PEI) onto the biomass surface in a two-step reaction. The presence of PEI on the biomass surface was verified by FTIR and X-ray photoelectron spectroscopy (XPS) analyses. Due to the high density of amine groups in the long chains of PEI molecules on the surface, the modified biomass was found to possess positive zeta potential at pH below 10.4 as well as high sorption capacity for anionic Cr(VI). Using the Langmuir adsorption isotherm, the maximum sorption capacity for Cr(VI) at a pH range of 4.3-5.5 was 5.37 mmol/g of biomass dry weight, the highest sorption capacity for Cr(VI) compared to other sorbents reported in the literature. Scanning electronic microscopy (SEM) provided evidence of chromium aggregates formed on the biomass surface. XPS results verified the presence of Cr(III) on the biomass surface in the pH range 2.5-10.5, suggesting that some Cr(VI) anions were reduced to Cr(III) during the sorption. The sorption kinetics indicated that redox reaction occurred on the biomass surface, and whether the converted Cr(III) ions were released to solution or adsorbed on the biomass depended on the solution pH. Sorption mechanisms including electrostatic interaction, chelation, and precipitation were found to be involved in the complex sorption of chromium on the PEI-modified biomass.

A wirelessly powered electro-acupuncture based on adaptive pulsewidth monophase stimulation.

Science.gov (United States)

Kiseok Song; Long Yan; Seulki Lee; Yoo, Jerald; Hoi-Jun Yoo

2011-04-01

A wirelessly powered electro-acupuncture (EA) system with adaptive-pulsewidth (APW) monophase stimulation is presented for convenient invasive medicine. The proposed system removes cumbersome wires connected between EA nodes and an EA controller in order to realize both patients' convenience and remedial values simultaneously. An ultra-low-power stimulator integrated circuit (IC) that is integrated on the flexible-printed-circuit board (F-PCB) is attached to the tip of a needle electrode. Combined with a conductive yarn helical antenna wound around the needle electrode, the EA node receives wireless power from the EA controller using 433 MHz with the maximum loss of 6 dB. A zero-Vth nMOS rectifier harvests a supply voltage of 1.0 V from a -16-dBm incoming power signal with 32% efficiency. To deal with a body impedance variation (BIV) in the range of 100-200 kΩ , the proposed APW stimulator IC, fabricated in a 0.18-μm 1P6M complementary metal-oxide semiconductor CMOS process and occupying 1.56 mm(2), enables constant charge injection of 80-nC/stimulation. To ensure the patients' safety, the EA node (a pair of EAs) shares ground and clock wires to operate in alternate monophase (AMP) fashion for neutralizing the injected charge. The proposed wirelessly powered EA node was verified by applying it to a chunk of pork as a body model with the wireless power supplied from an RF signal generator (output power of 10 dBm and located 30 cm away).

30 CFR 57.22202 - Main fans (I-A, I-B, I-C, II-A, III, V-A, and V-B mines).

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Main fans (I-A, I-B, I-C, II-A, III, V-A, and V... Main fans (I-A, I-B, I-C, II-A, III, V-A, and V-B mines). (a) Main fans shall be— (1) Installed on the... mines, provided with an automatic signal device to give an alarm when the fan stops. The signal device...

Neuronal migration disorders in microcephalic osteodysplastic primordial dwarfism type I/III.

Science.gov (United States)

Juric-Sekhar, Gordana; Kapur, Raj P; Glass, Ian A; Murray, Mitzi L; Parnell, Shawn E; Hevner, Robert F

2011-04-01

Microcephalic osteodysplastic primordial dwarfism (MOPD) is a rare microlissencephaly syndrome, with at least two distinct phenotypic and genetic types. MOPD type II is caused by pericentrin mutations, while types I and III appear to represent a distinct entity (MOPD I/III) with variably penetrant phenotypes and unknown genetic basis. The neuropathology of MOPD I/III is little understood, especially in comparison to other forms of lissencephaly. Here, we report postmortem brain findings in an 11-month-old female infant with MOPD I/III. The cerebral cortex was diffusely pachygyric, with a right parietal porencephalic lesion. Histologically, the cortex was abnormally thick and disorganized. Distinct malformations were observed in different cerebral lobes, as characterized using layer-specific neuronal markers. Frontal cortex was severely disorganized and coated with extensive leptomeningeal glioneuronal heterotopia. Temporal cortex had a relatively normal 6-layered pattern, despite cortical thickening. Occipital cortex was variably affected. The corpus callosum was extremely hypoplastic. Brainstem and cerebellar malformations were also present, as well as old necrotic foci. Findings in this case suggest that the cortical malformation in MOPD I/III is distinct from other forms of pachygyria-lissencephaly.

Monophasic Synovial Sarcoma of Prostatic Fascia: Case Report and Literature Review

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Lucio Olivetti

2015-01-01

Full Text Available Synovial sarcoma (SS primarily occurs in the para-articular soft tissue of the lower extremities in young adults and it is extremely rare in the prostatic region. We report a case of a 46-year-old man who presented with urinary retention. Pelvic ultrasound (US examination, computed tomography (CT, and magnetic resonance imaging (MRI demonstrated an 8.5 cm mass that appeared to originate in the prostatic fascia of the right lobe. Preoperative prostatic ultrasound transrectal needle biopsy revealed mesenchymal neoplastic tissue. Patient underwent surgery. The final pathologic findings were consistent with the diagnosis of monophasic synovial sarcoma.

Monophasic Synovial Sarcoma of Prostatic Fascia: Case Report and Literature Review.

Science.gov (United States)

Olivetti, Lucio; Benecchi, Luigi; Corti, Serena; Del Boca, Carlo; Ferrari, Matteo; Sergio, Pietro; Bercich, Luisa; Tanzi, Giulia

2015-01-01

Synovial sarcoma (SS) primarily occurs in the para-articular soft tissue of the lower extremities in young adults and it is extremely rare in the prostatic region. We report a case of a 46-year-old man who presented with urinary retention. Pelvic ultrasound (US) examination, computed tomography (CT), and magnetic resonance imaging (MRI) demonstrated an 8.5 cm mass that appeared to originate in the prostatic fascia of the right lobe. Preoperative prostatic ultrasound transrectal needle biopsy revealed mesenchymal neoplastic tissue. Patient underwent surgery. The final pathologic findings were consistent with the diagnosis of monophasic synovial sarcoma.

Toxic and hazardous chemicals, Title III and communities: An outreach manual for community groups

International Nuclear Information System (INIS)

McNeil, C.; Arkin, E.B.; McCallum, D.

1989-09-01

The manual was prepared for State and local government officials, local emergency planning committee (LEPCs), and other community groups that want to make Title III work. It is intended as a practical guide for those who have little or no previous experience in the field of communication, whose time must be snatched from home and office, and whose resources are limited. The manual has three major sections: Part I discusses planning, which is vital to the success of a communication program; Part II suggests ways to get and keep people involved, especially important because Title III affects so many different sectors of the community; Part III, a how-to-do-it section, talks about specific tasks, such as giving a speech or writing a press release. Appendices include a detailed explanation of the law, a glossary, a list of recent studies related to Title III communications, a list of educational materials, and a list of State contacts

Determination of free acid in highly concentrated organic and aqueous solutions of plutonium (IV) and uranium (VI) nitrate

International Nuclear Information System (INIS)

Wagner, J.F.; Lacour, J.L.

1989-01-01

Free acidity is an important parameter in the nuclear reprocessing control. The accuracy on the determination of free acidity is not really required in the nuclear reprocessing control itself but is necessary for certain types of analysis such as spectrophotometry (Pu (VI), Am (III),...), density determinations. A new titripotentiometric method for free acidity determination in concentrated U(VI) and Pu(IV) solutions is presented. This method is based on the complexing properties of dipicolinic acid (pyridine 2.6 dicarboxylic acid) and medium effect with H 2 O/DMSO mixture. This method can be used either in organic or aqueous phases with ratio /H + I/ metal ≥ 5.10 -2 and a relative standard deviation of 1%

Tunable thermoelectricity in monolayers of MoS2 and other group-VI dichalcogenides

KAUST Repository

Tahir, M

2014-10-31

We study the thermoelectric properties of monolayers of MoS2 and other group-VI dichalcogenides under circularly polarized off-resonant light. Analytical expressions are derived for the Berry phase mediated magnetic moment, orbital magnetization, as well as thermal and Nernst conductivities. Tuning of the band gap by off-resonant light enhances the spin splitting in both the valence and conduction bands and, thus, leads to a dramatic improvement of the spin and valley thermoelectric properties.

Tunable thermoelectricity in monolayers of MoS2 and other group-VI dichalcogenides

KAUST Repository

Tahir, M; Schwingenschlö gl, Udo

2014-01-01

We study the thermoelectric properties of monolayers of MoS2 and other group-VI dichalcogenides under circularly polarized off-resonant light. Analytical expressions are derived for the Berry phase mediated magnetic moment, orbital magnetization, as well as thermal and Nernst conductivities. Tuning of the band gap by off-resonant light enhances the spin splitting in both the valence and conduction bands and, thus, leads to a dramatic improvement of the spin and valley thermoelectric properties.

Investigation of Clostridium botulinum group III's mobilome content

NARCIS (Netherlands)

Woudstra, Cédric; Maréchal, Le Caroline; Souillard, Rozenn; Anniballi, Fabrizio; Auricchio, Bruna; Bano, Luca; Bayon-Auboyer, Marie Hélène; Koene, Miriam; Mermoud, Isabelle; Brito, Roseane B.; Lobato, Francisco C.F.; Silva, Rodrigo O.S.; Dorner, Martin B.; Fach, Patrick

2018-01-01

Clostridium botulinum group III is mainly responsible for botulism in animals. It could lead to high animal mortality rates and, therefore, represents a major environmental and economic concern. Strains of this group harbor the botulinum toxin locus on an unstable bacteriophage. Since the release of

Controlling the emission wavelength in group III-V semiconductor laser diodes

KAUST Repository

Ooi, Boon S.

2016-12-29

Methods are provided for modifying the emission wavelength of a semiconductor quantum well laser diode, e.g. by blue shifting the emission wavelength. The methods can be applied to a variety of semiconductor quantum well laser diodes, e.g. group III-V semiconductor quantum wells. The group III-V semiconductor can include AlSb, AlAs, Aln, AlP, BN, GaSb, GaAs, GaN, GaP, InSb, InAs, InN, and InP, and group III-V ternary semiconductors alloys such as AlxGai.xAs. The methods can results in a blue shifting of about 20 meV to 350 meV, which can be used for example to make group III-V semiconductor quantum well laser diodes with an emission that is orange or yellow. Methods of making semiconductor quantum well laser diodes and semiconductor quantum well laser diodes made therefrom are also provided.

Immediate remediation of heavy metal (Cr(VI)) contaminated soil by high energy electron beam irradiation

International Nuclear Information System (INIS)

Zhang, Jing; Zhang, Guilong; Cai, Dongqing; Wu, Zhengyan

2015-01-01

Highlights: • An immediate remediation method for Cr(VI) contaminated soil (CCS) was developed. • High energy electron beam (HEEB) irradiation could reduce Cr(VI) in CCS to Cr(III). • This effect was attributed to electrons, hydrated electrons, and reductive radicals. • This remediation method was effective, environmentally friendly, and low-cost. - Abstract: This work developed an immediate and high-performance remediation method for Cr(VI) contaminated soil (CCS) using high energy electron beam (HEEB) irradiation. The result indicated that, compared with γ-ray irradiation, HEEB irradiation displayed a significant reduction efficiency on Cr(VI) in CCS to Cr(III) with substantially lower toxicity, which was mainly attributed to the reduction effects of electrons, hydrated electrons, and reductive radicals generated in the irradiation process of HEEB. This work could provide a one-step and effective method for the remediation of heavy metal contaminated soil (HMCS)

Immediate remediation of heavy metal (Cr(VI)) contaminated soil by high energy electron beam irradiation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jing; Zhang, Guilong [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei 230031 (China); Bioenergy Forest Research Center of State Forestry Administration, Hefei 230031 (China); Cai, Dongqing, E-mail: dqcai@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei 230031 (China); Bioenergy Forest Research Center of State Forestry Administration, Hefei 230031 (China); Wu, Zhengyan, E-mail: zywu@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei 230031 (China); Bioenergy Forest Research Center of State Forestry Administration, Hefei 230031 (China)

2015-03-21

Highlights: • An immediate remediation method for Cr(VI) contaminated soil (CCS) was developed. • High energy electron beam (HEEB) irradiation could reduce Cr(VI) in CCS to Cr(III). • This effect was attributed to electrons, hydrated electrons, and reductive radicals. • This remediation method was effective, environmentally friendly, and low-cost. - Abstract: This work developed an immediate and high-performance remediation method for Cr(VI) contaminated soil (CCS) using high energy electron beam (HEEB) irradiation. The result indicated that, compared with γ-ray irradiation, HEEB irradiation displayed a significant reduction efficiency on Cr(VI) in CCS to Cr(III) with substantially lower toxicity, which was mainly attributed to the reduction effects of electrons, hydrated electrons, and reductive radicals generated in the irradiation process of HEEB. This work could provide a one-step and effective method for the remediation of heavy metal contaminated soil (HMCS)

Spectrophotometric Quantification of Toxicologically Relevant Concentrations of Chromium(VI in Cosmetic Pigments and Eyeshadow Using Synthetic Lachrymal Fluid Extraction

Directory of Open Access Journals (Sweden)

Sarah Wurster

2012-01-01

Full Text Available Chromium(VI salts are possible contaminants of the chromium(III pigments used as colorants in eyeshadow preparations. The use of products containing these contaminants poses acute risks for sensitization and contact allergies. Chromium(VI compounds are also classified as carcinogenic to humans (IARC group 1. An analytical method to analyse trace levels of chromium(VI in eyeshadow was developed in this study. The method is based on an extraction of the chromium(VI from the sample using a maximum extraction with alkali and additionally with synthetic lachrymal fluid to simulate physiological conditions. Following derivatization with 1,5-diphenylcarbazide, the extracted chromium(VI is then quantified by spectrophotometry (540 nm. Validation tests indicated a method standard deviation (inter- and intraday of 8.7% and a linear range up to 25 mg/kg. The average recovery was 107.9%, and the detection limit was 2.7 mg/kg. The applicability of the procedure was confirmed by the analysis of pigments and authentic eyeshadow matrices.

Low levels of methylmercury induce DNA damage in rats: protective effects of selenium

Energy Technology Data Exchange (ETDEWEB)

Grotto, Denise; Barcelos, Gustavo R.M.; Antunes, Lusania M.G.; Barbosa, Fernando [Universidade de Sao Paulo, Departamento de Analises Clinicas, Toxicologicas e Bromatologicas, Faculdade de Ciencias Farmaceuticas de Ribeirao Preto, Ribeirao Preto, Sao Paulo (Brazil); Valentini, Juliana [Universidade de Sao Paulo, Departamento de Analises Clinicas, Toxicologicas e Bromatologicas, Faculdade de Ciencias Farmaceuticas de Ribeirao Preto, Ribeirao Preto, Sao Paulo (Brazil); Universidade Federal de Santa Maria, Departamento de Analises Clinicas e Toxicologicas, Santa Maria, Rio Grande do Sul (Brazil); Angeli, Jose Pedro F. [Universidade de Sao Paulo, Departamento de Bioquimica, Instituto de Quimica, Sao Paulo (Brazil); Garcia, Solange C. [Universidade Federal de Santa Maria, Departamento de Analises Clinicas e Toxicologicas, Santa Maria, Rio Grande do Sul (Brazil)

2009-03-15

In this study we examined the possible antigenotoxic effect of selenium (Se) in rats chronically exposed to low levels of methylmercury (MeHg) and the association between glutathione peroxidase (GSH-Px) activity and DNA lesions (via comet assay) in the same exposed animals. Rats were divided into six groups as follows: (Group I) received water; (Group II) received MeHg (100 {mu}g/day); (Group III) received Se (2 mg/L drinking water); (Group IV) received Se (6 mg/L drinking water); (Group V) received MeHg (100 {mu}g/day) and Se (2 mg/L drinking water); (Group VI) received MeHg (100 {mu}g/day) and Se (6 mg/L drinking water). Total treatment time was 100 days. GSH-Px activity was determined spectrophotometrically and DNA damage was determined by comet assay. Mean GSH-Px activity in groups I, II, III, IV, V and VI were, respectively: 40.19{+-}17.21; 23.63{+-}6.04; 42.64{+-}5.70; 38.50{+-}7.15; 34.54{+-}6.18 and 41.39{+-}11.67 nmolNADPH/min/gHb. DNA damage was represented by a mean score from 0 to 300; the results for groups I, II, III, IV, V and VI were, respectively: 6.87{+-}3.27; 124.12{+-}13.74; 10.62{+-}3.81; 13.25{+-}1.76; 86.87{+-}11.95 and 76.25{+-}7.48. There was a significant inhibition of GSH-Px activity in group II compared with group I (P<0.05). Groups V and VI did not show a difference in enzyme activity compared with groups III and IV, showing the possible protective action of Se. Comet assay presented a significant difference in DNA migration between group II and group I (P<0.0001). Groups V and VI showed a significant reduction in MeHg-induced genotoxicity (P < 0.001) when compared with group II. A negative correlation (r = -0.559, P<0.05) was found between GSH-Px activity and DNA lesion, showing that the greater the DNA damage, the lower the GSH-Px activity. Our findings demonstrated the oxidative and genotoxic properties of MeHg, even at low doses. Moreover, Se co-administration reestablished GSH-Px activity and reduced DNA damage. (orig.)

Sn(II) oxy-hydroxides as potential adsorbents for Cr(VI)-uptake from drinking water: An X-ray absorption study

Energy Technology Data Exchange (ETDEWEB)

Pinakidou, Fani; Kaprara, Efthimia [Aristotle University of Thessaloniki, School of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece); Katsikini, Maria; Paloura, Eleni C.; Simeonidis, Konstantinos [Aristotle University of Thessaloniki, School of Physics, Department of Solid State Physics, 54124 Thessaloniki (Greece); Mitrakas, Manassis, E-mail: manasis@eng.auth.gr [Aristotle University of Thessaloniki, School of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece)

2016-05-01

The feasibility of implementing a Sn(II) oxy-hydroxide (Sn{sub 6}O{sub 4}(OH){sub 4}) for the reduction and adsorption of Cr(VI) in drinking water treatment was investigated using XAFS spectroscopies at the Cr-K-edge. The analysis of the Cr-K-edge XANES and EXAFS spectra verified the effective use of Sn{sub 6}O{sub 4}(OH){sub 4} for successful Cr(VI) removal. Adsorption isotherms, as well as dynamic Rapid Small Scale Test (RSSCT) in NSF water matrix showed that Sn{sub 6}O{sub 4}(OH){sub 4} can decrease Cr(VI) concentration below the upcoming regulation limit of 10 μg/L for drinking water. Moreover, an uptake capacity of 7.2 μg/mg at breakthrough concentration of 10 μg/L was estimated from the RSSCT, while the residual Cr(VI) concentration ranged at sub-ppb level for a significant period of the experiment. Furthermore, no evidence for the formation of Cr(OH){sub 3} precipitates was found. On the contrary, Cr(III)-oxyanions were chemisorbed onto SnO{sub 2}, which was formed after Sn(II)-oxidation during Cr(VI)-reduction. Nevertheless, changes in the type of Cr(III)-inner sphere complexes were observed after increasing surface coverage: Cr(III)-oxyanions preferentially sorb in a geometry which combines both bidentate binuclear ({sup 2}C) and monodentate ({sup 1}V) geometries, at the expense of the present bidentate mononuclear ({sup 2}E) contributions. On the other hand, the pH during sorption does not affect the adsorption mechanism of Cr(III)-species. The implementation of Sn{sub 6}O{sub 4}(OH){sub 4} in water treatment technology combines the advantage of rapidly reducing a large amount of Cr(VI) due to donation of two electrons by Sn(II) and also the strong chemisorption of Cr(III) in a combination of the {sup 2}C and {sup 1}V configurations, which enhances the safe disposal of spent adsorbents. - Highlights: • Effective Cr(VI) removal from drinking water by Sn{sub 6}O{sub 4}(OH){sub 4} • Sn{sub 6}O{sub 4}(OH){sub 4} transformation to SnO{sub 2} after Cr(VI

induced Oxidation of Chromium(iii) by Peroxodisulphate

African Journals Online (AJOL)

formation of Cr(VI) was observed as a first-order process at high [Cr(III)] and as a zero-order process at low [Cr(III)]. ..... thermodynamic equations, adapted to transition state theory. .... A theoretical rate law for the above-mentioned reaction.

Facile synthesis of AgI/BiOI-Bi{sub 2}O{sub 3} multi-heterojunctions with high visible light activity for Cr(VI) reduction

Energy Technology Data Exchange (ETDEWEB)

Wang, Qi [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China); The Brook Byer Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta 30332 (United States); Shi, Xiaodong; Liu, Enqin [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China); Crittenden, John C. [The Brook Byer Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta 30332 (United States); Ma, Xiangjuan; Zhang, Yi [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China); Cong, Yanqing, E-mail: yqcong@hotmail.com [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018 (China)

2016-11-05

Graphical abstract: Highly visible-light-active AgI/BiOI-Bi{sub 2}O{sub 3} with multi-heterojunctions was developed. - Highlights: • Visible-light-active AgI/BiOI-Bi{sub 2}O{sub 3} with multi-heterojunctions was prepared. • Highly enhanced photocatalytic reduction of Cr(VI) was observed. • k{sub Cr(VI)} on AgI/BiOI-Bi{sub 2}O{sub 3} increased by ca.16 times relative to Bi{sub 2}O{sub 3}. • Decreased E{sub g}, shifted E{sub fb} and reduced charge transfer resistance were observed. • Simultaneous reduction of Cr(VI) and degradation of organics were achieved. - Abstract: AgI sensitized BiOI-Bi{sub 2}O{sub 3} composite (AgI/BiOI-Bi{sub 2}O{sub 3}) with multi-heterojunctions was prepared using simple etching-deposition process. Different characterization techniques were performed to investigate the structural, optical and electrical properties of the as-prepared photocatalysts. It was found that the ternary AgI/BiOI-Bi{sub 2}O{sub 3} composite exhibited: (1) improved photocurrent response, (2) smaller band gap, (3) greatly reduced charge transfer resistance and (4) negative shift of flat band potential, which finally led to easier generation and more efficient separation of photo-generated electron-hole pairs at the hetero-interfaces. Thus, for the reduction of Cr(VI), AgI/BiOI-Bi{sub 2}O{sub 3} exhibited excellent photocatalytic activity under visible light irradiation at near neutral pH. AgI/BiOI-Bi{sub 2}O{sub 3} was optimized when the initial molar ratio of KI to Bi{sub 2}O{sub 3} and AgNO{sub 3} to Bi{sub 2}O{sub 3} was 1:1 and 10%, respectively. The estimated k{sub Cr(VI)} on optimized AgI/BiOI-Bi{sub 2}O{sub 3} was about 16 times that on pure Bi{sub 2}O{sub 3}. Good stability was also observed in cyclic runs, indicating that the current multi-heterostructured photocatalyst is highly desirable for the remediation of Cr(VI)-containing wastewater.

Synthesis, characterization and stability of Cr(III) and Fe(III) hydroxides

Energy Technology Data Exchange (ETDEWEB)

Papassiopi, N.; Vaxevanidou, K.; Christou, C.; Karagianni, E.; Antipas, G.S.E., E-mail: gantipas@metal.ntua.gr

2014-01-15

Highlights: • Fe(III)–Cr(III) hydroxides enhance groundwater quality better than pure Cr(III) compounds. • Crystalline Cr(OH){sub 3}·3H{sub 2}O was unstable, with a solubility higher than 50 μg/l. • Amorphous Cr(OH){sub 3}(am) was stable with a solubility lower than 50 μg/l in the range 5.7 < pH < 11. • For mixed Fe{sub 0.75}Cr{sub 0.25}(OH){sub 3}, the stability region was extended to 4.8 < pH < 13.5. -- Abstract: Chromium is a common contaminant of soils and aquifers and constitutes a major environmental problem. In nature, chromium usually exists in the form of two oxidation states, trivalent, Cr(III), which is relatively innocuous for biota and for the aquatic environment, and hexavalent, Cr(VI) which is toxic, carcinogenic and very soluble. Accordingly, the majority of wastewater and groundwater treatment technologies, include a stage where Cr(VI) is reduced to Cr(III), in order to remove chromium from the aqueous phase and bind the element in the form of environmentally stable solid compounds. In the absence of iron the final product is typically of the form Cr(OH){sub 3}·xH{sub 2}O whereas in the presence of iron the precipitate is a mixed Fe{sub (1−x)}Cr{sub x}(OH){sub 3} phase. In this study, we report on the synthesis, characterisation and stability of mixed (Fe{sub x},Cr{sub 1−x})(OH){sub 3} hydroxides as compared to the stability of Cr(OH){sub 3}. We established that the plain Cr(III) hydroxide, abiding to the approximate molecular formula Cr(OH){sub 3}·3H{sub 2}O, was crystalline, highly soluble, i.e. unstable, with a tendency to transform into the stable amorphous hydroxide Cr(OH){sub 3}(am) phase. Mixed Fe{sub 0.75}Cr{sub 0.25}(OH){sub 3} hydroxides were found to be of the ferrihydrite structure, Fe(OH){sub 3}, and we correlated their solubility to that of a solid solution formed by plain ferrihydrite and the amorphous Cr(III) hydroxide. Both our experimental results and thermodynamic calculations indicated that mixed Fe(III)–Cr(III

An “on-off-on” fluorescent nanoprobe for recognition of chromium(VI) and ascorbic acid based on phosphorus/nitrogen dual-doped carbon quantum dot

Energy Technology Data Exchange (ETDEWEB)

Gong, Xiaojuan, E-mail: gxj1124@sxu.edu.cn [Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); Liu, Yang; Yang, Zhenhua; Shuang, Shaomin [Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); Zhang, Zeyu [Faculty of Science, Beijing University of Chemical Technology, Beijing, 100029 (China); Dong, Chuan, E-mail: dc@sxu.edu.cn [Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China)

2017-05-22

Chromium (VI) [Cr(VI)] is a harsh environmental contaminates and has been proved to be highly toxic, carcinogenic and mutagenic. Therefore, developing an inexpensive, good selective and highly sensitive nanoprobe for the detection of Cr(VI) is in urgent demand. Recently, the highly fluorescent carbon quantum dots (CQDs) have been successfully utilized as efficient fluorescent nanoprobes for the detection of ions, pH and molecular substances. In this work, an “on-off” fluorescence phosphorus/nitrogen dual-doped CQDs (PNCQDs) probe was developed for the determination of Cr(VI) based on inner filter effect (IFE). The proposed PNCQDs nanoprobe shows its distinct merits of simplicity, convenience, fast implementation, good selectivity and high sensitivity towards Cr(VI), allowing its potential application in the determination of Cr(VI) in environment and biosystem. In addition, the chelation effect of the functional groups in reductant and Cr(VI), and the easy-conversion of Cr(VI) to reduced states (i.e. Cr(III) and Cr(0)) by reductants makes the minimization of IFE with a concomitant recovery of PNCQDs fluorescence possible. Hence, the PNCQDs/Cr(VI) hybrid was used as an “off-on” fluorescence probe for sensing ascorbic acid (AA), which is a model reductant. For the detection of Cr(VI), the linear range and the limit of detection achieved were 1.5–30 μmol/L and 23 nmol/L, respectively. For the detection of AA, the linear range and the limit of detection obtained were 5.0–200 μmol/L and 1.35 μmol/L, respectively. The as-constructed “on-off-on” PNCQDs fluorescent nanoprobe was successfully applied for detecting Cr(VI) and AA in biosystem. Furthermore, the as-constructed fluorescent sensing system was successfully applied to the analyses of AA in fresh fruits and in commercial fruit juices with satisfactory results. - Highlights: • Fast synthesis of phosphorus/nitrogen dual-doped CQDs (PNCQDs) by acid-base neutralization carbonization method. �

Effective Adsorption/Reduction of Cr(VI) Oxyanion by Halloysite@Polyaniline Hybrid Nanotubes.

Science.gov (United States)

Zhou, Tianzhu; Li, Cuiping; Jin, Huiling; Lian, Yangyang; Han, Wenmei

2017-02-22

Halloysite@polyaniline (HA@PANI) hybrid nanotubes are synthesized by the in situ chemical polymerization of aniline on halloysite clay nanotubes. By facilely tuning the dopant acid, pH, and apparent weight proportion for aniline (ANI) and halloysite (HA) nanotubes in the synthesis process, PANI with tuned oxidation state, doping extent, and content are in situ growing on halloysite nanotubes. The reaction system's acidity is tuned by dopant acid, such as HCl, H 2 SO 4 , HNO 3 , and H 3 PO 4 . The adsorption result shows the fabricated HA@PANI hybrid nanotubes can effectively adsorb Cr(VI) oxyanion and the adsorption ability changes according to the dopant acid, pH, and apparent weight proportion for ANI and HA in the synthesis process. Among them, the HA@PANI fabricated with HCl as dopant acid tuning the pH at 0.5 and 204% apparent weight proportion for ANI and HA (HP/0.5/204%-HCl) shows the highest adsorption capacity. The adsorption capacity is in accordance well with the doping extent of PANI in HA@PANI. Furthermore, when HP/0.5/204%-HCl is redoped with HNO 3 , H 2 SO 4 , and H 3 PO 4 , the adsorption capacity declines, implying the dopant acid in the process of redoping exhibits a marked effect on Cr(VI) oxyanion adsorption for the HA@PANI hybrid nanotubes. HP/0.5/204%-HCl and HP/0.5/204%-H 3 PO 4 have demonstrated good regenerability with an above 80% removal ratio after four cycles. Moreover, the HA@PANI adsorbent has better sedimentation ability than that of pure PANI. The adsorption behavior is in good agreement with Langmuir and pseudo second-order equations, indicating the adsorption of HA@PANI for Cr(VI) oxyanion is chemical adsorption. FT-IR and XPS of HA@PANI after Cr(VI) oxyanion adsorption indicate that the doped amine/imine groups (-NH + /═N + - groups) are the main adsorption sites for the removal of Cr(VI) oxyanion by electrostatic adsorption and reduction of the adsorbed Cr (VI) oxyanion to Cr(III) simultaneously.

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

Science.gov (United States)

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.

Environmental survey of Region VI, Haltenbanken, 2009; Miljoeundersoekelse i Region VI, Haltenbanken, 2009

Energy Technology Data Exchange (ETDEWEB)

Holm, May-Helen; Cochrane, Sabine; Mannvik, Hans-Petter; Wasbotten, Ingar Halvorsen

2010-07-01

There has been an environmental investigation in Region VI Halten Bank. This report presents the results of the chemical and biological assays performed on samples from a total of 316 stations in 16 fields and 15 regional stations. A status of environmental conditions in the region is given at the end of the report. (AG)

The potential of compost-based biobarriers for Cr(VI) removal from contaminated groundwater: Column test

International Nuclear Information System (INIS)

Boni, Maria Rosaria; Sbaffoni, Silvia

2009-01-01

This paper presents the results of a column reactor test, aiming at evaluating the performance of a biological permeable barrier made of low-cost waste materials, for Cr(VI) removal from contaminated groundwater. A 1:1 by volume mixture of green compost and siliceous gravel was tested as reactive medium in the experimental activity. A 10 mg/l Cr(VI) contaminated solution was used and the residual Cr(VI) concentration along the column height and in the outlet was determined in the water samples collected daily. Also pH, redox potential and COD were analyzed. At the end of the test, the reactive medium was characterized in terms of Cr(VI) and total chromium. The Cr(VI) removal efficiency was higher than 99% during the entire experimental activity. The influence of the biological activity on Cr(VI) removal efficiency was evaluated by varying the organic carbon and nitrogen dosages in the contaminated solution fed to the system; a removal decrease was observed when the organic carbon was not enough to sustain the microbial metabolism. The Cr(VI) removal was strictly linked to the biological activity of the native biomass of compost. No Cr(III) was detected in the outlet: the Cr(III) produced was entrapped in the solid matrix. Two main processes involved were: adsorption on the organic-based matrix and reduction into Cr(III) mediated by the anaerobic microbial metabolism of the bacteria residing in green compost. Siliceous gravel was used as the structure matrix, since its contribution to the removal was almost negligible. Thanks to the proven efficiency and to the low-cost, the reactive medium used can represent a valid alternative to conventional approaches to chromium remediation.

Radiotherapeutic aspects of the treatment of adult patients with supradiaphragmatic Hodgkin's disease CS I/II. Pt. 1; Regarding the indications of primary and adjuvant radiotherapy. Fragen und Aspekte zur Radiotherapie bei erwachsenen Patienten mit lokalisierten supradiaphragmalen Stadien (CS I/II) eines Morbus Hodgkin. T. 1; Fragen und Aspekte zu den Indikationen einer primaeren und einer adjuvanten Radiotherapie

Energy Technology Data Exchange (ETDEWEB)

Glanzmann, C. (Universitaetsspital, Klinik fuer Radio-Onkologie, Zurich (Switzerland)); Luetolf, U.M. (Universitaetsspital, Klinik fuer Radio-Onkologie, Zurich (Switzerland))

1993-08-01

Randomized studies of chemo- vs radiotherapy in patients with PS I/II A and some PS III A have shown conflicting results. Patients with supra-diaphragmatic Hodkin's disease and CS I/II can be subdivided according to radiotherapy as: 1. Patients with a very low or a low recurrence risk of approximately 10 to 20%: Patients less than 40 years old and CS I/II A NS/LP with less than three involved regions and no bulky mediastinal mass and an ESR below 30 mm. In the other patients, primary irradiation of an extended mantle field without a staging laparotomy is an acceptable primary treatment, achieving a recurrence-free survival rate of approximately 80%. Another option is a staging laparotomy with splenectomy and a mantle radiotherapy for PS I/II. Few groups prefer primary chemotherapy alone or some type of a reduced chemotherapy with lesser toxicity combined with localized radiotherapy and long-term observations of a larger group of patients after the last type of treatment have to confirm the excellent early results. 2. Patients with an intermediate recurrence risk of approximately 20 to 40%: Patients, who do not belong to group one or group 3. Patients less than 50 years old with CS I/II and an ESR less than 50 mm and without bulky mediastinal involvement and with one of the following signs: Three involved regions or MC or one B symptom. A patient with more than one of these signs or with two or three B symptoms should be classified in group 3. For these patients, we recommend staging laparotomy and radiotherapy if PS I/II or primary chemotherapy with or without radiotherapy of the involved regions. 3. Patients with a high recurrence risk (40% or higher): (Abstract Truncated)

Kinetics of chromium (VI) reduction by ferrous iron

International Nuclear Information System (INIS)

Batchelor, B.; Schlautman, M.; Hwang, I.; Wang, R.

1998-09-01

Chromium is a primary inorganic contaminant of concern at the Pantex Plant. Chromium concentrations have been found to be two orders of magnitude higher than the drinking water standards, particularly in certain wells in the perched aquifer below Zone 12. In situ reduction of a mobile form of chromium, Cr(VI) to an immobile form, Cr(III), was examined as a viable option to active soil restoration. Successfully immobilizing chromium in the vadose zone as Cr(III) will reduce the amount of chromium that reaches the groundwater table. The results from the solution experiments indicated that chromium was rapidly and stoichiometrically reduced by Fe(II) in solution. Also, the slurry experiments showed that the aquifer solids removed Fe(II) from solution, but a portion of the iron removed remained available for reaction with Cr(VI), but at a slower rate. A model to predict different amounts of iron pseudo-components was developed, which allowed prediction of iron amounts required to reduce chromium under in situ conditions

IN VITRO Cr(VI SPECIATION IN SYNTHETIC SALIVA AFTER RELEASING FROM ORTHODONTIC BRACKETS USING SILICA-APTES SEPARATION AND GF AAS DETERMINATION

Directory of Open Access Journals (Sweden)

Maciel S. Luz

Full Text Available A method for Cr(VI speciation in synthetic saliva after releasing from orthodontic brackets, using silica nanoparticles organofunctionalized with (3-aminopropyltriethoxysilane (APTES for Cr(III/Cr(VI separation and GF AAS determination is proposed. Under the optimized conditions, Cr(VI speciation was performed using 150 mg of silica organofunctionalized with 2.0% (v v-1 of APTES at pH 8. It was observed different sensitivity when calibrations of GF AAS were performed using Cr(III or Cr(VI as standard solutions. Consequently, calibrations using stoichiometric mixtures (Cr(III + Cr(VI were used for total Cr determination and calibration using Cr(VI was used only for the determination of this specie. The reliability of the proposed silica-APTES separation procedure and GF AAS determination was checked by addition of both species in synthetic saliva. Recoveries ranging from 97 to 110% were obtained. The repeatability, based on the relative standard deviation (RSD inter days was less than 6%. A corrosion test was carried out on 20 orthodontic brackets from two different models, after immersion in synthetic saliva (pH=6.0 at 37 °C with agitation (125 rpm for 24 h. It was observed that about 40% of the total chromium released from the analyzed orthodontic brackets was Cr(VI.

Epithermal neutron activation analysis of CR(VI)-reducer basalt-inhabiting bacteria

International Nuclear Information System (INIS)

Tsibakhashvili, N.Ya.; Kalabegishvili, T.L.; Murusidze, I.G.; Mosulishvili, L.M.; Frontas'eva, M.V.; Kirkesali, E.I.; Aksenova, N.G.; Holman, H.Y.

2005-01-01

Epithermal neutron activation analysis (ENAA) has been applied to studying elemental composition of Cr(VI)-reducer bacteria isolated from polluted basalts from the Republic of Georgia. Cr(VI)-reducing ability of the bacteria was examined by electron spin resonance (ESR) demonstrating that the bacteria differ in the rates of Cr(VI) reduction. A well-pronounced correlation between the ability of the bacteria to accumulate Cr(VI) and their ability to reduce Cr(V) to Cr(III) observed in our experiments is discussed. Elemental analysis of these bacteria also revealed that basalt-inhabiting bacteria are distinguished by relative contents of essential elements such as K, Na, Mg, Fe, Mn, Zn, and Co. A high rate of Cr(III) formation correlates with a high concentration of Co in the bacterium. ENAA detected some similarity in the elemental composition of the bacteria. The relatively high contents of Fe detected in the bacteria (140-340 μg/g of dry weight) indicate bacterial adaptation to the environmental conditions typical of the basalts. The concentrations of at least 12-19 different elements ranging from major- to ultratrace ones were determined in each type of bacteria simultaneously. The range of concentrations spans over 8 orders of magnitude

The roles of polycarboxylates in Cr(VI)/sulfite reaction system: Involvement of reactive oxygen species and intramolecular electron transfer

Energy Technology Data Exchange (ETDEWEB)

Jiang, Bo, E-mail: bjiang86upc@163.com [State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao 266580, Shandong (China); School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266033 (China); Wang, Xianli; Liu, Yukun [State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao 266580, Shandong (China); Wang, Zhaohui [College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China); Southern Cross GeoScience, Southern Cross University, Lismore, NSW 2480 (Australia); Zheng, Jingtang, E-mail: jtzheng03@163.com [State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao 266580, Shandong (China); Wu, Mingbo, E-mail: wumb@upc.edu.cn [State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao 266580, Shandong (China)

2016-03-05

Highlights: • The formations of SO{sub 4}·{sup −} and OH·, involve in Cr(VI) reduction induced by S(IV). • Affinity of polycarboxylate to Cr(VI) accelerates Cr(VI) reduction rate. • Polycarboxylates can act as electron donors for Cr(VI) reduction retrenching S(IV). • Only oxalate can enhance the formations of SO{sub 4}·{sup −} and OH· in Cr(VI)/S(IV) system. - Abstract: In this study, the effects of polycarboxylates on both Cr(VI) reduction and S(IV) consumption in Cr(VI)/S(IV) system was investigated in acidic solution. Under aerobic condition, the productions of reactive oxygen species (ROS), i.e., SO{sub 4}·{sup −} and OH·, have been confirmed in S(IV) reducing Cr(VI) process by using electron spin resonance and fluorescence spectrum techniques, leading to the excess consumption of S(IV). However, when polycarboxylates (oxalic, citric, malic and tartaric acid) were present in Cr(VI)/S(IV) system, the affinity of polycarboxylates to CrSO{sub 6}{sup 2−} can greatly promote the reduction of Cr(VI) via expanding the coordination of Cr(VI) species from tetrahedron to hexahedron. Besides, as alternatives to S(IV), these polycarboxylates can also act as electron donors for Cr(VI) reduction via intramolecular electron transfer reaction, which is dependent on the energies of the highest occupied molecular orbital of these polycarboxylates. Notably, the variant electron donating capacity of these polycarboxylates resulted in different yield of ROS and therefore the oxidation efficiencies of other pollutants, e.g., rhodamine B and As(III). Generally, this study does not only shed light on the mechanism of S(IV) reducing Cr(VI) process mediated by polycarboxylates, but also provides an escalated, cost-effective and green strategy for the remediation of Cr(VI) using sulfite as a reductant.

Epithermal Neutron Activation Analysis (ENAA) of Cr(VI)-reducer Basalt-inhabiting Bacteria

CERN Document Server

Tsibakhashvili, N Ya; Kirkesali, E I; Aksenova, N G; Kalabegishvili, T L; Murusidze, I G; Mosulishvili, L M; Holman, H Y N

2005-01-01

Epithermal neutron activation analysis (ENAA) has been applied to studying elemental composition of Cr(VI)-reducer bacteria isolated from polluted basalts from the Republic of Georgia. Cr(VI)-reducing ability of the bacteria was examined by electron spin resonance (ESR) demonstrating that the bacteria differ in the rates of Cr(VI) reduction. A well-pronounced correlation between the ability of the bacteria to accumulate Cr(V) and their ability to reduce Cr(V) to Cr(III) observed in our experiments is discussed. Elemental analysis of these bacteria also revealed that basalt-inhabiting bacteria are distinguished by relative contents of essential elements such as K, Na, Mg, Fe, Mn, Zn, and Co. A high rate of Cr(III) formation correlates with a high concentration of Co in the bacterium. ENAA detected some similarity in the elemental composition of the bacteria. The relatively high contents of Fe detected in the bacteria (140-340 $\\mu $g/g of dry weight) indicate bacterial adaptation to the environmental condition...

Clinical effects of Angelica dahurica dressing on patients with I-II phase pressure sores.

Science.gov (United States)

Gong, Fen; Niu, Junzhi; Pei, Xing

2016-11-02

Angelica dahurica is a well-known traditional Chinese Medicine (TCM), while little information is available about its effects on pressure sores. We aimed to investigate the clinical effect of Angelica dahurica on patients with I-II phase pressure sores, as well as the underlying mechanism. Patients (n = 98) with phase I and phase II pressure sores were enrolled and randomly assigned to control and treated groups. In addition to holistic nursing, patients in the control group received compound clotrimazole cream, while patients in the treated group received continuous 4 weeks of external application of Angelica dahurica dressing. Therapeutic effect was recorded, along with the levels of interleukin-8 (IL-8), epidermal growth factor (EGF), transforming growth factor (TGF)-β, and vascular endothelial growth factor (VEGF). Besides, HaCaT cells were cultured with different concentrations of Angelica dahurica, and then cell viability, clone formation numbers, cell cycle, and levels of cyclin D1 and cyclin-dependent kinase (CDK) 2 were determined. The total effective rate in the treated group was significantly higher than in the control group. Levels of IL-8, EGF, TGF-β, and VEGF were statistically increased by Angelica dahurica. In addition, the cell viability and clone formation numbers were significantly upregulated by Angelica dahurica in a dose-dependent manner. Also, the percentage of cells in G0/G1 phase, and levels of cyclin D1 and CDK2 were significantly elevated. Our results suggest that Angelica dahurica may provide an effective clinical treatment for I-II phase pressure sores.

Determination of the solubility of Np(IV), Pu(III) - (VI),Am(III) - (VI), and Te(IV), (V) hydroxo compounds in 0.5 - 14 M NaOH solutions

Energy Technology Data Exchange (ETDEWEB)

Delegard, C.H.

1996-09-24

The solubilities of Am(III), Np(IV), Pu(IV), Tc(IV), Np(V), Pu(V), Am(V), and Tc(V) hydroxo compounds were studied in 0.5 to 14 M NaOH solutions at 25{+-}2 {degrees}C. The effects of fluoride, phosphate, carbonate, oxalate, and some other organic complexing agents on the solubilities of Np(IV), Pu(IV), and TC(IV) hydroxides were investigated at 1.0 and 4.0 M NAOH. Some predictions were made on the dissolved (I.V) and (V) species present in alkali solutions.

"Vi har musikk i skolen for å bli bedre til å synge!" Elevens egen stemme om sangaktiviteten i skolens musikkopplæring

Directory of Open Access Journals (Sweden)

Odd Magne Bøe

2010-12-01

Full Text Available Artikkelen fokuserer på elevenes egne opplevelser omkring sangaktiviteter i skolens musikkopplæring. Sang i skolen drøftes i lys av de rammene vi finner i ”Læreplanverket for Kunnskapsløftet” (LK06. Et sentralt spørsmål vil være om elever i ulike aldre forteller om endring av musikkaktiviteter i takt med et utvidet register i faget. Jeg vil i tillegg diskutere i hvilken grad elevens stemme vil kunne bringe fram ny viten om musikkfaget. Artikkelen er tredelt. Først beskrives målet med studien og begrunnelser for valg av metode. Deretter presenteres resultater fra empirien basert på kvalitative data fra elevintervjuer. I den tredje delen tar drøftingen utgangspunkt i de funn jeg gjorde i min studie.

Chromium isotope inventory of Cr(VI)-polluted groundwaters at four industrial sites in Central Europe

Science.gov (United States)

Novak, Martin; Martinkova, Eva; Chrastny, Vladislav; Stepanova, Marketa; Curik, Jan; Szurmanova, Zdenka; Cron, Marcel; Tylcer, Jiri; Sebek, Ondrej

2016-04-01

Chromium is one of the most toxic elements, especially in its dissolved Cr(VI) form. In the Czech Republic (Central Europe), massive contamination of groundwater has been reported at more than 200 industrial operations. Under suitable conditions, i.e., low Eh, and high availability of reductive agents, Cr(VI) in groundwater may be spontaneously reduced to solid, largely non-toxic Cr(III). This process is associated with a Cr isotope fractionation, with the residual liquid Cr(VI) becoming enriched in the heavier isotope 53Cr. At industrial operations that have been closed and/or where no further leakage of Cr(VI) occurs, the contaminated groundwater plume may be viewed as a closed system. At such sites, an increasing degree of Cr(VI) reduction should result in an increasing del53/52Cr value of the residual liquid. Here we present del53/52Cr systematics at four contaminated Czech sites, focusing on groundwaters. At two of the four sites (Zlate Hory, Loucna) we were also able to analyze the source of contamination. Chromium in the electroplating solutes was isotopically relatively light, with del53/52Cr values 4.0 per mil (mean of +1.7 per mil); at Letnany, del53/52Cr ranged between +2.0 and +4.5 per mil (mean of +3.2 per mil); and at Velesin, del53/52Cr ranged between +0.5 and +4.5 per mil (mean of +2.7 per mil). Cr(VI) reduction may proceed at Zlate Hory and Loucna, where del53/52Cr(VI) values in groundwater were on average higher than those of the contamination source. At these two sites, our Cr isotope data are not consistent with the existing estimates of the amount of dissolved and precipitated Cr: The pool size of solid Cr(III) in the soil was estimated at 6600 and 500 kg at Zlate Hory and Loucna, respectively. At the same time, the pool size of dissolved Cr(VI) was estimated at 50 and 1.2 kg at Zlate Hory and Loucna, respectively. It follows that, at both sites, less than 1 % of the entire Cr that had leaked into the aquifer an a liquid form remained in the

IgE and IgG cross-reactivity among Lol p I and Lol p II/III. Identification of the C-termini of Lol p I, II, and III as cross-reactive structures.

Science.gov (United States)

van Ree, R; van Leeuwen, W A; van den Berg, M; Weller, H H; Aalberse, R C

1994-04-01

In this study, the homologous C-termini of Lol p I, Lol p II, and Lol p III were shown to contain cross-reactive B-cell epitopes. This was demonstrated by inhibition studies with purified Lol p I, II, and III and synthetic peptides of their C-termini. It was ruled out that the observed cross-reactivity was caused by cross-contamination of the purified allergens. Both human IgE and IgG bound to the C-terminus of Lol p I. These antibodies were cross-reactive with Lol p II and, more specifically, with its C-terminus. Within a small panel of allergic patients, no cross-reactivity with Lol p III was found. A hyperimmune polyclonal rabbit antiserum against Lol p I also recognized the Lol p I C-terminus. As for human antibodies, cross-reactivity with Lol p II and its C-terminus was demonstrated. Cross-reactivity with Lol p III was demonstrated with C-terminal peptides, but not with native Lol p III. A polyclonal rabbit antiserum against Lol p II bound to the C-terminal peptides of both Lol p II and III. This binding was inhibited with Lol p I, confirming that cross-reactive structures exist not only on the C-termini of Lol p II and Lol p I, but also of Lol p III and Lol p I. The existence of cross-reactivity between Lol p I and Lol p II and III possibly contributes to the frequently observed cosensitization for these allergens in grass-pollen-allergic patients.

Progress report: The Energy and Industry Subgroup of IPCC Working Group III

International Nuclear Information System (INIS)

Yokobori, Keiichi

1990-01-01

The Intergovernmental Panel on Climate Change (IPCC) was established in November 1988 under the joint auspices of UNEP and the World Meteorological Organization (WMO). Working Group III, or the Response Strategies Working Group (RSWG), was established to formulate strategies to respond to challenges arising from global climate warming. The Energy and Industry Subgroup (EIS) was created by the RSWG at its meeting in January-February 1989 to facilitate the formulation of strategies to control, i.e. prevent or reduce, the accumulation of greenhouse gases (GHGs) such as CO 2 , CFCs, NO 2 , CH, etc. The following article gives a brief summary of EIS activities, based mainly on records of discussion at the relevant meetings. (author). 1 tab

Diverse Reactions of Thiophenes, Selenophenes, and Tellurophenes with Strongly Oxidizing I(III) PhI(L)2 Reagents.

Science.gov (United States)

Egalahewa, Sathsara; Albayer, Mohammad; Aprile, Antonino; Dutton, Jason L

2017-02-06

We report the outcomes of the reactions of aromatic group 16 thiophene, selenophene, and tellurophene rings with the I(III) oxidants PhI(OAc)(OTf) and [PhI(Pyr) 2 ][OTf] 2 (Pyr = pyridine). In all reactions, oxidative processes take place, with generation of PhI as the reduction product. However, with the exception of tellurophene with PhI(OAc)(OTf), +4 oxidation state complexes are not observed, but rather a variety of other processes occur. In general, where a C-H unit is available on the 5-membered ring, an electrophilic aromatic substitution reaction of either -IPh or pyridine onto the ring occurs. When all positions are blocked, reactions with PhI(OAc)(OTf) give acetic and triflic anhydride as the identifiable oxidative byproducts, while [PhI(Pyr) 2 ][OTf] 2 gives pyridine electrophilic aromatic substitution onto the peripheral rings. Qualitative mechanistic studies indicate that the presence of the oxidizable heteroatom is required for pyridine to act as an electrophile in a substantial manner.

International Working Group on Past Reactors Thirteenth Annual Meeting. Summary Report. Part III

International Nuclear Information System (INIS)

1981-04-01

The Thirteenth Annual Meeting of the IAEA International Working Group on Fast Reactors was held at the IAEA Headquarters, Vienna, Austria from 9 to 11 April 1980. The Summary Report (Part I) contains the Minutes of the Meeting. The Summary Report (Part II) contains the papers which review the national programme in the field of LMFBRs and other presentations at the Meeting. The Summary Report (Part III) contains the discussions on the review of the national programmes

Quantum state-to-state dynamics for the quenching process of Br(2P1/2) + H2(v(i) = 0, 1, j(i) = 0).

Science.gov (United States)

Xie, Changjian; Jiang, Bin; Xie, Daiqian; Sun, Zhigang

2012-03-21

Quantum state-to-state dynamics for the quenching process Br((2)P(1/2)) + H(2)(v(i) = 0, 1, j(i) = 0) → Br((2)P(3/2)) + H(2)(v(f), j(f)) has been studied based on two-state model on the recent coupled potential energy surfaces. It was found that the quenching probabilities have some oscillatory structures due to the interference of reflected flux in the Br((2)P(1/2)) + H(2) and Br((2)P(3/2)) + H(2) channels by repulsive potential in the near-resonant electronic-to-vibrational energy transfer process. The final vibrational state resolved integral cross sections were found to be dominated by the quenching process Br((2)P(1/2)) + H(2)(v) → Br((2)P(3/2)) + H(2)(v+1) and the nonadiabatic reaction probabilities for Br((2)P(1/2)) + H(2)(v = 0, 1, j(i) = 0) are quite small, which are consistent with previous theoretical and experimental results. Our calculated total quenching rate constant for Br((2)P(1/2)) + H(2)(v(i) = 0, j(i) = 0) at room temperature is in good agreement with the available experimental data. © 2012 American Institute of Physics

Highly trabeculated structure of the human endocardium underlies asymmetrical response to low-energy monophasic shocks

Science.gov (United States)

Connolly, Adam; Robson, Matthew D.; Schneider, Jürgen; Burton, Rebecca; Plank, Gernot; Bishop, Martin J.

2017-09-01

Novel low-energy defibrillation therapies are thought to be driven by virtual-electrodes (VEs), due to the interaction of applied monophasic electric shocks with fine-scale anatomical structures within the heart. Significant inter-species differences in the cardiac (micro)-anatomy exist, however, particularly with respect to the degree of endocardial trabeculations, which may underlie important differences in response to low-energy defibrillation protocols. Understanding the interaction of monophasic electric fields with the specific human micro-anatomy is therefore imperative in facilitating the translation and optimisation of these promising experimental therapies to the clinic. In this study, we sought to investigate how electric fields from implanted devices interact with the highly trabeculated human endocardial surface to better understand shock success in order to help optimise future clinical protocols. A bi-ventricular human computational model was constructed from high resolution (350 μm) ex-vivo MR data, including anatomically accurate endocardial structures. Monophasic shocks were applied between a basal right ventricular catheter and an exterior ground. Shocks of varying strengths were applied with both anodal [positive right ventricle (RV) electrode] and cathodal (negative RV electrode) polarities at different states of tissue refractoriness and during induced arrhythmias. Anodal shocks induced isolated positive VEs at the distal side of "detached" trabeculations, which rapidly spread into hyperpolarised tissue on the surrounding endocardial surfaces following the shock. Anodal shocks thus depolarised more tissue 10 ms after the shock than cathodal shocks where the propagation of activation from VEs induced on the proximal side of "detached" trabeculations was prevented due to refractory endocardium. Anodal shocks increased arrhythmia complexity more than cathodal shocks during failed anti-arrhythmia shocks. In conclusion, multiple detached

Bioreduction of Uranium(VI) Complexed with Citric Acid by Clostridia Affects its Structure and Mobility

International Nuclear Information System (INIS)

Francis, A.; Dodge, C.

2008-01-01

Uranium contamination of the environment from mining and milling operations, nuclear-waste disposal, and ammunition use is a widespread global problem. Natural attenuation processes such as bacterial reductive precipitation and immobilization of soluble uranium is gaining much attention. However, the presence of naturally occurring organic ligands can affect the precipitation of uranium. Here, we report that the anaerobic spore-forming bacteria Clostridia, ubiquitous in soils, sediments, and wastes, capable of reduction of Fe(III) to Fe(II), Mn(IV) to Mn(II), U(VI) to U(IV), Pu(IV) to Pu(III), and Tc(VI) to Tc(IV); reduced U(VI) associated with citric acid in a dinuclear 2:2 U(VI):citric acid complex to a biligand mononuclear 1:2 U(IV):citric acid complex, which remained in solution, in contrast to reduction and precipitation of uranium. Our findings show that U(VI) complexed with citric acid is readily accessible as an electron acceptor despite the inability of the bacterium to metabolize the complexed organic ligand. Furthermore, it suggests that the presence of organic ligands at uranium-contaminated sites can affect the mobility of the actinide under both oxic and anoxic conditions by forming such soluble complexes.

Optimizing Cr(VI) and Tc(VII) remediation through nano-scale biomineral engineering

International Nuclear Information System (INIS)

Cutting, R.S.; Coker, V.S.; Telling, N.D.; Kimber, R.L.; Pearce, C.I.; Ellis, B.; Lawson, R; van der Laan, G.; Pattrick, R.A.D.; Vaughan, D.J.; Arenholz, E.; Lloyd, J.R.

2009-01-01

To optimize the production of biomagnetite for the bioremediation of metal oxyanion contaminated waters, the reduction of aqueous Cr(VI) to Cr(III) by two biogenic magnetites and a synthetic magnetite was evaluated under batch and continuous flow conditions. Results indicate that nano-scale biogenic magnetite produced by incubating synthetic schwertmannite powder in cell suspensions of Geobacter sulfurreducens is more efficient at reducing Cr(VI) than either biogenic nano-magnetite produced from a suspension of ferrihydrite 'gel' or synthetic nano-scale Fe 3 O 4 powder. Although X-ray Photoelectron Spectroscopy (XPS) measurements obtained from post-exposure magnetite samples reveal that both Cr(III) and Cr(VI) are associated with nanoparticle surfaces, X-ray Magnetic Circular Dichroism (XMCD) studies indicate that some Cr(III) has replaced octahedrally coordinated Fe in the lattice of the magnetite. Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) measurements of total aqueous Cr in the associated solution phase indicated that, although the majority of Cr(III) was incorporated within or adsorbed to the magnetite samples, a proportion (∼10-15 %) was released back into solution. Studies of Tc(VII) uptake by magnetites produced via the different synthesis routes also revealed significant differences between them as regards effectiveness for remediation. In addition, column studies using a γ-camera to obtain real time images of a 99m Tc(VII) radiotracer were performed to visualize directly the relative performances of the magnetite sorbents against ultra-trace concentrations of metal oxyanion contaminants. Again, the magnetite produced from schwertmannite proved capable of retaining more (∼20%) 99m Tc(VII) than the magnetite produced from ferrihydrite, confirming that biomagnetite production for efficient environmental remediation can be fine-tuned through careful selection of the initial Fe(III) mineral substrate supplied to Fe(III

Optimizing Cr(VI) and Tc(VII) remediation through nano-scale biomineral engineering

Energy Technology Data Exchange (ETDEWEB)

Cutting, R. S.; Coker, V. S.; Telling, N. D.; Kimber, R. L.; Pearce, C. I.; Ellis, B.; Lawson, R; van der Laan, G.; Pattrick, R.A.D.; Vaughan, D.J.; Arenholz, E.; Lloyd, J. R.

2009-09-09

To optimize the production of biomagnetite for the bioremediation of metal oxyanion contaminated waters, the reduction of aqueous Cr(VI) to Cr(III) by two biogenic magnetites and a synthetic magnetite was evaluated under batch and continuous flow conditions. Results indicate that nano-scale biogenic magnetite produced by incubating synthetic schwertmannite powder in cell suspensions of Geobacter sulfurreducens is more efficient at reducing Cr(VI) than either biogenic nano-magnetite produced from a suspension of ferrihydrite 'gel' or synthetic nano-scale Fe{sub 3}O{sub 4} powder. Although X-ray Photoelectron Spectroscopy (XPS) measurements obtained from post-exposure magnetite samples reveal that both Cr(III) and Cr(VI) are associated with nanoparticle surfaces, X-ray Magnetic Circular Dichroism (XMCD) studies indicate that some Cr(III) has replaced octahedrally coordinated Fe in the lattice of the magnetite. Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) measurements of total aqueous Cr in the associated solution phase indicated that, although the majority of Cr(III) was incorporated within or adsorbed to the magnetite samples, a proportion ({approx}10-15 %) was released back into solution. Studies of Tc(VII) uptake by magnetites produced via the different synthesis routes also revealed significant differences between them as regards effectiveness for remediation. In addition, column studies using a {gamma}-camera to obtain real time images of a {sup 99m}Tc(VII) radiotracer were performed to visualize directly the relative performances of the magnetite sorbents against ultra-trace concentrations of metal oxyanion contaminants. Again, the magnetite produced from schwertmannite proved capable of retaining more ({approx}20%) {sup 99m}Tc(VII) than the magnetite produced from ferrihydrite, confirming that biomagnetite production for efficient environmental remediation can be fine-tuned through careful selection of the initial Fe(III) mineral

Type I-II laryngeal cleft: clinical course and outcome.

Science.gov (United States)

Slonimsky, Guy; Carmel, Eldar; Drendel, Michael; Lipschitz, Noga; Wolf, Michael

2015-04-01

Laryngeal cleft (LC) is a rare congenital anomaly manifesting in a variety of symptoms, including swallowing disorders and aspirations, dyspnea, stridor and hoarseness. The mild forms (types I-II) may be underdiagnosed, leading to protracted symptomatology and morbidity. To evaluate the diagnostic process, clinical course, management and outcome in children with type I-II laryngeal clefts. We conducted a retrospective case analysis for the years 2005-2012 in a tertiary referral center. Seven children were reviewed: five boys and two girls ranging in age from birth to 5 years. The most common presenting symptoms were cough, aspirations and pneumonia. Evaluation procedures included fiber-optic laryngoscopy (FOL), direct laryngoscopy (DL) and videofluoroscopy. Other pathologies were seen in three children. Six children underwent successful endoscopic surgery and one child was treated conservatively. The postoperative clinical course was uneventful in most of the cases. Types I-II LC should be considered in the differential diagnosis of children presenting with protracted cough and aspirations. DL is crucial for establishing the diagnosis. Endoscopic surgery is safe and should be applied promptly when conservative measures fail.

Identification of Multiple Soluble Fe(III Reductases in Gram-Positive Thermophilic Bacterium Thermoanaerobacter indiensis BSB-33

Directory of Open Access Journals (Sweden)

Subrata Pal

2014-01-01

Full Text Available Thermoanaerobacter indiensis BSB-33 has been earlier shown to reduce Fe(III and Cr(VI anaerobically at 60°C optimally. Further, the Gram-positive thermophilic bacterium contains Cr(VI reduction activity in both the membrane and cytoplasm. The soluble fraction prepared from T. indiensis cells grown at 60°C was found to contain the majority of Fe(III reduction activity of the microorganism and produced four distinct bands in nondenaturing Fe(III reductase activity gel. Proteins from each of these bands were partially purified by chromatography and identified by mass spectrometry (MS with the help of T. indiensis proteome sequences. Two paralogous dihydrolipoamide dehydrogenases (LPDs, thioredoxin reductase (Trx, NADP(H-nitrite reductase (Ntr, and thioredoxin disulfide reductase (Tdr were determined to be responsible for Fe(III reductase activity. Amino acid sequence and three-dimensional (3D structural similarity analyses of the T. indiensis Fe(III reductases were carried out with Cr(VI reducing proteins from other bacteria. The two LPDs and Tdr showed very significant sequence and structural identity, respectively, with Cr(VI reducing dihydrolipoamide dehydrogenase from Thermus scotoductus and thioredoxin disulfide reductase from Desulfovibrio desulfuricans. It appears that in addition to their iron reducing activity T. indiensis LPDs and Tdr are possibly involved in Cr(VI reduction as well.

Direct monophasic replacement of fatty acid by DMSA on SPION surface

Energy Technology Data Exchange (ETDEWEB)

Gogoi, M. [Department of Physics, Tezpur University (Central University), Tezpur 784028 (India); Deb, P., E-mail: pdeb@tezu.ernet.in [Department of Physics, Tezpur University (Central University), Tezpur 784028 (India); Interface Chemistry and Surface Engineering, Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Strasse 1, 40237 Duesseldorf (Germany); Vasan, G.; Keil, P.; Kostka, A.; Erbe, A. [Interface Chemistry and Surface Engineering, Max-Planck-Institut fuer Eisenforschung GmbH, Max-Planck-Strasse 1, 40237 Duesseldorf (Germany)

2012-10-01

Highlights: Black-Right-Pointing-Pointer Monophasic replacement of fatty acid coating. Black-Right-Pointing-Pointer Ultrastable dispersion of hydrophilic SPION in a wide pH range. Black-Right-Pointing-Pointer Unaltered microstructure and property on surface modification. - Abstract: Tailoring the surface and understanding the surface characteristics is necessary for biomedical applications of superparamagnetic nanoparticles. In this paper, superparamagnetic iron oxide nanoparticles (SPIONs) were prepared by thermal decomposition of iron nitrate in presence of stearic acid as surfactant. Due to the multilayer organization of surfactant molecules over the nanoparticle surface, the surface potential can be tuned by pH changes and hence the nanoparticles can be made dispersible in nonpolar as well as in polar solvents. We have presented a simple, facile procedure for controlled replacement of stearic acid from maghemite surface and subsequent derivatization by biocompatible dimercaptosuccinic acid (DMSA) to obtain ultrastable hydrophilic nanoparticles with unaltered morphology, phase and properties. The surface chemistry of the functionalized SPIONs was analyzed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) revealing the presence of bound and unbound thiol groups and disulfides, leading to its prolonged stability in aqueous medium. The consequence of spatially selective functionalization on the stability and solubility of surface hydrophilic SPION has also been realized.

Chemoprevention with green propolis green propolis extracted in L-lysine versus carcinogenesis promotion with L-lysine in N-Butyl-N-[4-hydroxybutyl] nitrosamine (BBN induced rat bladder cancer Quimioprevenção com própolis verde extraído em L-Lisina versus promoção da carcinogênese como L-Lisina em ratos induzidos ao câncer de bexiga pelo N-Butyl-N-[4-hydroxybutyl] nitrosamine (BBN

Directory of Open Access Journals (Sweden)

Conceição Aparecida Dornelas

2012-02-01

Full Text Available PURPOSE: To determine the effects of green propolis extracted in L-lysine (WSDP and of L- lysine for 40 weeks on induced rat bladder carcinogenesis. METHODS: The animals (groups I, II, III, IV, V and VI received BBN during 14 weeks. Group I was treated with propolis 30 days prior received BBN, and then these animals were treated daily with propolis; Groups II and III was treated with subcutaneous and oral propolis (respectively concurrently with BBN. The animals of Group IV were treated L-lysine; Group V received water subcutaneous; and Group VI received only to BBN. Among the animals not submitted to carcinogenesis induction, Group VII received propolis, Group VIII received L-lysine and Group IX received water. RESULTS: The carcinoma incidence in Group I was lower than that of control (Group VI. The carcinoma multiplicity in Group IV was greater than in Group VI. All animals treated with L-lysine developed carcinomas, and they were also more invasive in Group IV than in controls. On the other hand, Group VIII showed no bladder lesions. CONCLUSION: The WSDP is chemopreventive against rat bladder carcinogenesis, if administered 30 days prior to BBN , and that L-lysine causes promotion of bladder carcinogenesis.OBJETIVO: Determinar os efeitos da própolis verde extraída em L - Lisina (WSDP e da L-Lisina por 40 semanas em ratos induzidos a carcinogênese de bexiga. MÉTODOS: Os animais (grupos I, II, III, IV, V e VI receberam BBN por 14 semanas. O grupo I foi tratado com própolis 30 dias antes de receber BBN e em seguida estes animais foram tratados diariamente com própolis; Os grupos II e III foram tratados com própolis subcutânea e oral (respectivamente e concorretemente com BBN. Os animais do grupo IV foram tratados com L- Lisina; o grupo V recebeu água subcutânea; o grupo VI recebeu apenas BBN. Entre os animais não submetidos a indução de carcinogênese, Grupo VII, receberam própolis, Grupo VIII, receberam L-Lisina e Grupo IX

HERBIG-HARO OBJECTS IN THE LUPUS I AND III MOLECULAR CLOUDS

International Nuclear Information System (INIS)

Wang Hongchi; Henning, Thomas

2009-01-01

We performed a deep search for Herbig-Haro (HH) objects toward the Lupus I and III clouds, covering a sky area of ∼ 1 and ∼ 0.5 deg 2 , respectively. In total, 11 new HH objects, HH 981--991, are discovered. The HH objects both in Lupus I and in Lupus III tend to be concentrated in small areas. The HH objects detected in Lupus I are located in a region of radius 0.26 pc near the young star Sz 68. The abundance of HH objects shows that this region of the cloud is active in on-going star formation. HH objects in the Lup III cloud are concentrated in the central part of the cloud around the Herbig Ae/Be stars HR 5999 and 6000. HH 981 and 982 in Lupus I are probably driven by the young brown dwarf SSTc2d J154457.9-342340 which has a mass of 50 M J . HH 990 and 991 in Lup III align well with the HH 600 jet emanating from the low-mass star Par-Lup3-4, and are probably excited by this low-mass star of spectral type M5. High proper motions for HH 228 W, E, and E2 are measured, which confirms that they are excited by the young star Th 28. In contrast, HH 78 exhibits no measurable proper motion in the time span of 18 years, indicating that HH 78 is unlikely part of the HH 228 flow. The HH objects in Lup I and III are generally weak in terms of brightness and dimension in comparison to HH objects we detected with the same technique in the R CrA and Cha I clouds. Through a comparison with the survey results from the Spitzer c2d program, we find that our optical survey is more sensitive, in terms of detection rate, than the Spitzer IRAC survey to high-velocity outflows in the Lup I and III clouds.

Vertical group III-V nanowires on si, heterostructures, flexible arrays and fabrication

Science.gov (United States)

Wang, Deli; Soci, Cesare; Bao, Xinyu; Wei, Wei; Jing, Yi; Sun, Ke

2015-01-13

Embodiments of the invention provide a method for direct heteroepitaxial growth of vertical III-V semiconductor nanowires on a silicon substrate. The silicon substrate is etched to substantially completely remove native oxide. It is promptly placed in a reaction chamber. The substrate is heated and maintained at a growth temperature. Group III-V precursors are flowed for a growth time. Preferred embodiment vertical Group III-V nanowires on silicon have a core-shell structure, which provides a radial homojunction or heterojunction. A doped nanowire core is surrounded by a shell with complementary doping. Such can provide high optical absorption due to the long optical path in the axial direction of the vertical nanowires, while reducing considerably the distance over which carriers must diffuse before being collected in the radial direction. Alloy composition can also be varied. Radial and axial homojunctions and heterojunctions can be realized. Embodiments provide for flexible Group III-V nanowire structures. An array of Group III-V nanowire structures is embedded in polymer. A fabrication method forms the vertical nanowires on a substrate, e.g., a silicon substrate. Preferably, the nanowires are formed by the preferred methods for fabrication of Group III-V nanowires on silicon. Devices can be formed with core/shell and core/multi-shell nanowires and the devices are released from the substrate upon which the nanowires were formed to create a flexible structure that includes an array of vertical nanowires embedded in polymer.

strong>Hvad skal vi med en hjerne?strong>

DEFF Research Database (Denmark)

Hermansen, Judy

2009-01-01

neurologen Antonio Damasio, at sikre vores overlevelse og velbefindende (i nævnte rækkefølge). Vi ved, at der findes såkaldte belønningsstrukturer i hjernen på både dyr og mennesker, som aktiverer følelser af velbehag, når vi gør "det rigtige", dvs. noget der er godt for os. Men hvordan de mere konkret...

[Amaurosis and contralateral cranial nerve pairs III and VI paralysis after peribulbar block - Case report].

Science.gov (United States)

Leme, Fábio Caetano Oliveira; Moro, Eduardo Toshiyuki; Ferraz, Alexandre Alberto Fontana

2016-08-20

Peribulbar anesthesia (PBA) has emerged as a safer option compared with intraconal retrobulbar block. Still, PBA may not be considered without risk. Numerous complications have been described when performing this technique. This report aims to describe a rare case of amaurosis and contralateral paralysis while attempting to perform a PBA. Male patient, 75-year old, physical status ASA II, undergoing cataract surgery by phacoemulsification with intraocular lens implantation. Sedated with fentanyl and midazolam and subjected to PBA. There were no complications during surgery. After finishing the procedure, the patient reported lack of vision in the contralateral eye. Akinesia of the muscles innervated by the cranial nerve pairs III and VI, ptosis, and medium-sized pupils unresponsive to light stimulus were observed. Four hours after anesthesia, complete recovery of vision and eyelid and eyeball movements was seen in the non-operated eye. During PBA, structures located in the intraconal space can be accidentally hit leading to complications such as described in the above report. Following the technical guidelines and using appropriate size needles may reduce the risk of such complication, but not completely. Copyright © 2016. Publicado por Elsevier Editora Ltda.

Lack of chart reminder effectiveness on family medicine resident JNC-VI and NCEP III guideline knowledge and attitudes

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Upshur Ross EG

2004-07-01

Full Text Available Abstract Background The literature demonstrates that medical residents and practicing physicians have an attitudinal-behavioral discordance concerning their positive attitudes towards clinical practice guidelines (CPG, and the implementation of these guidelines into clinical practice patterns. Methods A pilot study was performed to determine if change in a previously identified CPG compliance factor (accessibility would produce a significant increase in family medicine resident knowledge and attitude toward the guidelines. The primary study intervention involved placing a summary of the Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI and the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (NCEP III CPGs in all patient (>18 yr. charts for a period of three months. The JNC VI and NCEP III CPGs were also distributed to each Wayne State family medicine resident, and a copy of each CPG was placed in the preceptor's area of the involved clinics. Identical pre- and post- intervention questionnaires were administered to all residents concerning CPG knowledge and attitude. Results Post-intervention analysis failed to demonstrate a significant difference in CPG knowledge. A stastically significant post-intervention difference was found in only on attitude question. The barriers to CPG compliance were identified as 1 lack of CPG instruction; 2 lack of critical appraisal ability; 3 insufficient time; 4 lack of CPG accessibility; and 5 lack of faculty modeling. Conclusion This study demonstrated no significant post intervention changes in CPG knowledge, and only one question that reflected attitude change. Wider resident access to dedicated clinic time, increased faculty modeling, and the implementation of an electronic record/reminder system that uses a team-based approach are compliance factors that

Redox equilibria in the In(III)-In(I)-In system in aqueous KBr solutions, I. potentiometric and coulometric study

International Nuclear Information System (INIS)

Malyszko, E.; Malyszko, J.

1993-01-01

The reproportionation of In(I) ions in acidic potassium bromide solutions was studied by means of the coulometric and potentiometric method. The formal potentials of the In(III)/In(I), In(III)/In and In(I)/In redox couples as well as the equilibrium constants of the reaction In(III) + 2 In 3 In(I) were determined at a background electrolyte concentration ranging from 1 to 4 mol dm -3 . Based on the experimental results, a scheme of the reproportionation reaction was proposed with regard to the participation of bromide ions. In addition, the diffusion coefficient of In(I) ions was determined using the chronopotentiometric technique

Thermal neutron detector and gamma-ray spectrometer utilizing a single material

Science.gov (United States)

Stowe, Ashley; Burger, Arnold; Lukosi, Eric

2017-05-02

A combined thermal neutron detector and gamma-ray spectrometer system, including: a detection medium including a lithium chalcopyrite crystal operable for detecting thermal neutrons in a semiconductor mode and gamma-rays in a scintillator mode; and a photodetector coupled to the detection medium also operable for detecting the gamma rays. Optionally, the detection medium includes a .sup.6LiInSe.sub.2 crystal. Optionally, the detection medium comprises a compound formed by the process of: melting a Group III element; adding a Group I element to the melted Group III element at a rate that allows the Group I and Group III elements to react thereby providing a single phase I-III compound; and adding a Group VI element to the single phase I-III compound and heating; wherein the Group I element includes lithium.

Uranium (III)-Plutonium (III) co-precipitation in molten chloride

Science.gov (United States)

Vigier, Jean-François; Laplace, Annabelle; Renard, Catherine; Miguirditchian, Manuel; Abraham, Francis

2018-02-01

Co-management of the actinides in an integrated closed fuel cycle by a pyrochemical process is studied at the laboratory scale in France in the CEA-ATALANTE facility. In this context the co-precipitation of U(III) and Pu(III) by wet argon sparging in LiCl-CaCl2 (30-70 mol%) molten salt at 705 °C is studied. Pu(III) is prepared in situ in the molten salt by carbochlorination of PuO2 and U(III) is then introduced as UCl3 after chlorine purge by argon to avoid any oxidation of uranium up to U(VI) by Cl2. The oxide conversion yield through wet argon sparging is quantitative. However, the preferential oxidation of U(III) in comparison to Pu(III) is responsible for a successive conversion of the two actinides, giving a mixture of UO2 and PuO2 oxides. Surprisingly, the conversion of sole Pu(III) in the same conditions leads to a mixture of PuO2 and PuOCl, characteristic of a partial oxidation of Pu(III) to Pu(IV). This is in contrast with coconversion of U(III)-Pu(III) mixtures but in agreement with the conversion of Ce(III).

Current percolation and the V-I transition in YBa{sub 2}Cu{sub 3}O{sub 7} bicrystals and granular coated conductors

Energy Technology Data Exchange (ETDEWEB)

Evetts, J E; Hogg, M J; Glowacki, B A; Rutter, N A; Tsaneva, V N [Department of Materials Science and IRC in Superconductivity, University of Cambridge, Cambridge CB2 3QZ (United Kingdom)

1999-07-01

There is considerable interest in the dynamics of vortices in granular 'coated conductors' consisting of a 2D network of low angle grain boundaries (LAGBs). The V-I characteristic of the conductor is determined by a combination of flux vortex channelling along the grain boundaries and current percolation within the grain network.In this work it is shown that measurements of viscous flow for a YBa{sub 2}Cu{sub 3}O{sub 7} bicrystal LAGB can be applied in a statistical model that predicts the characteristic V-I response for a particular grain-to-grain dispersion of grain boundary angles. (author)

Reversed phase chromatographic behaviour of Pu (III), Pu (IV) and Pu (VI) in presence of α-hydroxyisobutyric acid

International Nuclear Information System (INIS)

Jaison, P.G.; Telmore, V.M.; Kumar, Pranaw

2016-01-01

Understanding the aqueous chemistry of plutonium is important in process conditions as well as in environmental conditions. Since plutonium possesses multiple oxidation states which can coexist in solution, a reliable method for the identification of these oxidation states is essential to understand its physical and chemical processes. The identification of plutonium oxidation states is conventionally determined through a series of liquid-liquid extraction procedures using selective extractants. Spectroscopic and laser based techniques also have been used for the identification of its oxidation state in solutions. Liquid chromatographic behavior of different oxidation states of Pu and other actinide ions is reported to correlate their retention behaviour with stability constants. Objective of the present work is to study the reversed phase chromatography behavior of the three oxidation states of plutonium viz. Pu(III), Pu(IV) and Pu(VI) in presence of á-hydroxyisobutyric acid (HIBA) as an eluent

Study on Cr(VI) Leaching from Cement and Cement Composites

Science.gov (United States)

Palascakova, Lenka; Kanuchova, Maria

2018-01-01

This paper reports an experimental study on hexavalent chromium leaching from cement samples and cement composites containing silica fume and zeolite additions that were subjected to various leaching agents. The water-soluble Cr(VI) concentrations in cements ranged from 0.2 to 3.2 mg/kg and represented only 1.8% of the total chromium content. The presence of chromium compounds with both chromium oxidation states of III and VI was detected in the cement samples by X-ray photoelectron spectroscopy (XPS). Leaching tests were performed in a Britton-Robinson buffer to simulate natural conditions and showed increased dissolution of Cr(VI) up to 6 mg/kg. The highest amount of leached hexavalent chromium was detected after leaching in HCl. The findings revealed that the leaching of chromium from cements was higher by 55–80% than that from the cement composites. A minimum concentration was observed for all cement samples when studying the relationship between the soluble Cr(VI) and the cement storage time. PMID:29690550

Remediation of U(VI)-contaminated water using zero-valent iron

International Nuclear Information System (INIS)

Abdelouas, A.; Gong, W.; Lutze, W.; Nuttall, E.

1999-01-01

We investigated the possibility of U(VI) reduction by zero-valent iron (Fe 0 ). We conducted batch experiments with granular iron and solutions containing 0.25 and 9.3 mg L -1 U(VI) at 24 deg C. The solution pH ranges between 2 and 9. In all experiments uranium removal was complete within several hours to several days regardless of the pH value. The reduced uranium precipitated as poorly crystallized hydrated uraninite, UO 2 .nH 2 O. The reduction of U(VI) to U(IV) by Fe 0 was found to be the principal mechanism of U removal from the solution. Other mechanisms such as U(VI) sorption on the newly formed Fe(III) hydroxides are insignificant. These results show that zero-valent iron can be used to remedy U-contaminated waters from uranium mines and mill tailings sites, the pH of which usually ranges between 2 and 9. (authors)

Group III mGlu receptor agonists potentiate the anticonvulsant effect of AMPA and NMDA receptor block.

Science.gov (United States)

De Sarro, Giovambattista; Chimirri, Alba; Meldrum, Brian S

2002-09-06

We report the anticonvulsant action in DBA/2 mice of two mGlu Group III receptor agonists: (R,S)-4-phosphonophenylglycine, (R,S)-PPG, a compound with moderate mGlu8 selectivity, and of (1S,3R,4S)-1-aminocyclopentane-1,2,4-tricarboxylic acid, ACPT-1, a selective agonist for mGlu4alpha receptors. Both compounds, given intracerebroventricularly at doses which did not show marked anticonvulsant activity, produced a consistent shift to the left of the dose-response curves (i.e. enhanced the anticonvulsant properties) of 1-(4'-aminophenyl)-3,5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin-4-one hydrochloride, CFM-2, a noncompetitive AMPA receptor antagonist, and 3-((+/-)-2-carboxypiperazin-4-yl)-1-phosphonic acid, CPPene, a competitive NMDA receptor antagonist, in DBA/2 mice. In addition, (R,S)-PPG and ACPT-1 administered intracerebroventricularly prolonged the time course of the anticonvulsant properties of CFM-2 (33 micromol/kg, i.p.) and CPPene (3.3 micromol/kg, i.p.) administered intraperitoneally. We conclude that modest reduction of synaptic glutamate release by activation of Group III metabotropic receptors potentiates the anticonvulsant effect of AMPA and NMDA receptor blockade. Copyright 2002 Elsevier Science B.V.

Nickel(I) and nickel(III) complexes of substituted tetraaza macrocycles formed by pulse radiolysis and electrochemistry of nickel(II) precursors

International Nuclear Information System (INIS)

Bernhardt, P.V.; Lawrance, G.A.; Sangster, D.F.

1988-01-01

The square-planar nickel(II) complexes of the ligands 8-methyl-8-nitro-1,3,6,10,13,15-hexaazatricyclo[13.1.1.1/sup 13,15/]octadecane, 8-amino-8-methyl-1,3,6,10,13,15-hexaazatricyclo[13.1.1.1/sup 13,15/]octadecane, 3,7-bis(2-aminoethyl)-1,3,5,7-tetraazabicyclo[3.3.1]nonane, and 9-methyl-9-nitro-1,4,7,11-tetraazacyclotridecane (I-IV) react rapidly with hydroxyl radicals and aquated electrons (e/sub aq/). The initial transient products of these reactions decay via first-order kinetics within a few milliseconds in neutral aqueous solution at 22/degrees/C in all cases. Electronic spectra and decay rate constants, as well as formation rate constants, are reported for all transients. Reaction of the nitro-substituted complexes with e/sub aq/ led to electron addition to the nitro group rather than to the metal center; otherwise, a Ni/sup I/ transient is observed. Following reaction with OH, the product of the initial decay remains a Ni/sup III/ species. This is more long-lived, and stabilization of Ni/sup III/ by axial coordination of the pendant amine in II is indicated. No notable stabilization of Ni/sup I/ or Ni/sup III/ from the presence of the bicyclic azamethylene football in I-III occurs. Cyclic voltammetry in acetonitrile identified both one-electron oxidation and one-electron reduction processes for the nickel(II) complexes, as well as nitro group reduction, where this group was pendant to the macrocycle. 34 references, 3 figures, 3 tables

Conserved water-mediated hydrogen bond network between TM-I, -II, -VI, and -VII in 7TM receptor activation

DEFF Research Database (Denmark)

Nygaard, Rie; Hansen, Louise Valentin; Mokrosinski, Jacek

2010-01-01

Five highly conserved polar residues connected by a number of structural water molecules together with two rotamer micro-switches, TrpVI:13 and TyrVII:20, constitute an extended hydrogen bond network between the intracellular segments of TM-I, -II, -VI, and -VII of 7TM receptors. Molecular dynamics...... to apparently function as a catching trap for water molecules. Mutational analysis of the beta2-adrenergic receptor demonstrated that the highly conserved polar residues of the hydrogen bond network were all important for receptor signaling but served different functions, some dampening constitutive activity...... (AsnI:18, AspII:10, and AsnVII:13), whereas others (AsnVII:12 and AsnVII:16) located one helical turn apart and sharing a water molecule were shown to be essential for agonist-induced signaling. It is concluded that the conserved water hydrogen bond network of 7TM receptors constitutes an extended...

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

Science.gov (United States)

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.

Sn(II) oxy-hydroxides as potential adsorbents for Cr(VI)-uptake from drinking water: An X-ray absorption study.

Science.gov (United States)

Pinakidou, Fani; Kaprara, Efthimia; Katsikini, Maria; Paloura, Eleni C; Simeonidis, Konstantinos; Mitrakas, Manassis

2016-05-01

The feasibility of implementing a Sn(II) oxy-hydroxide (Sn6O4(OH)4) for the reduction and adsorption of Cr(VI) in drinking water treatment was investigated using XAFS spectroscopies at the Cr-K-edge. The analysis of the Cr-K-edge XANES and EXAFS spectra verified the effective use of Sn6O4(OH)4 for successful Cr(VI) removal. Adsorption isotherms, as well as dynamic Rapid Small Scale Test (RSSCT) in NSF water matrix showed that Sn6O4(OH)4 can decrease Cr(VI) concentration below the upcoming regulation limit of 10μg/L for drinking water. Moreover, an uptake capacity of 7.2μg/mg at breakthrough concentration of 10μg/L was estimated from the RSSCT, while the residual Cr(VI) concentration ranged at sub-ppb level for a significant period of the experiment. Furthermore, no evidence for the formation of Cr(OH)3 precipitates was found. On the contrary, Cr(III)-oxyanions were chemisorbed onto SnO2, which was formed after Sn(II)-oxidation during Cr(VI)-reduction. Nevertheless, changes in the type of Cr(III)-inner sphere complexes were observed after increasing surface coverage: Cr(III)-oxyanions preferentially sorb in a geometry which combines both bidentate binuclear ((2)C) and monodentate ((1)V) geometries, at the expense of the present bidentate mononuclear ((2)E) contributions. On the other hand, the pH during sorption does not affect the adsorption mechanism of Cr(III)-species. The implementation of Sn6O4(OH)4 in water treatment technology combines the advantage of rapidly reducing a large amount of Cr(VI) due to donation of two electrons by Sn(II) and also the strong chemisorption of Cr(III) in a combination of the (2)C and (1)V configurations, which enhances the safe disposal of spent adsorbents. Copyright © 2016 Elsevier B.V. All rights reserved.

Vi behøver innovation

DEFF Research Database (Denmark)

McAloone, Tim C.

2007-01-01

-Produktion og Maskiner. Innovation og bæredygtighed er to områder som vi i Skandinavien giver meget stor opmærksomhed for at kunne vedligeholde vores globale konkurrencekraft og stærke velfærdssamfund. Gennem årene har mange brancher bidraget til skabelsen af vidensbaserede innovationer, og det faktum, at de......Analyse: Vi behøver innovation En ny miljøbølge ruller, og danske virksomheder bør ride med Af Tim McAloone, fredag 02. feb 2007 kl. 04:50 Tim McAloone Lektor og ph.d. ved Institut for mekanik, energi og konstruktion ved DTU. Tim McAloone skriver fremover jævnligt kommentarer i Ingeniøren...... skandinaviske lande er relativt små, har ledt til en interessant evne til at etablere og derefter samarbejde inden for tætte netværk, som strækker sig over både faglige og geografiske grænser. Samtidig har vi set miljøhensyn vinde og tabe samfundsmæssig og industriel opmærksomhed på en nærmest periodisk basis...

Multi-crystalline II-VI based multijunction solar cells and modules

Science.gov (United States)

Hardin, Brian E.; Connor, Stephen T.; Groves, James R.; Peters, Craig H.

2015-06-30

Multi-crystalline group II-VI solar cells and methods for fabrication of same are disclosed herein. A multi-crystalline group II-VI solar cell includes a first photovoltaic sub-cell comprising silicon, a tunnel junction, and a multi-crystalline second photovoltaic sub-cell. A plurality of the multi-crystalline group II-VI solar cells can be interconnected to form low cost, high throughput flat panel, low light concentration, and/or medium light concentration photovoltaic modules or devices.

Determination of Cr(VI) in wood specimen: A XANES study at the Cr K edge

International Nuclear Information System (INIS)

Strub, E.; Plarre, R.; Radtke, M.; Reinholz, U.; Riesemeier, H.; Schoknecht, U.; Urban, K.; Juengel, P.

2008-01-01

The content of chromium in different oxidation states in chromium-treated wood was studied with XANES (X-ray absorption near-edge structure) measurements at the Cr K absorption edge. It could be shown that wood samples treated with Cr(VI) (pine and beech) did still contain a measurable content of Cr(VI) after four weeks conditioning. If such wood samples were heat exposed for 2 h with 135 deg. C prior conditioning, Cr(VI) was no longer detected by XANES, indicating a complete reduction to chromium (III)

New insights into Trypanosoma cruzi evolution, genotyping and molecular diagnostics from satellite DNA sequence analysis.

Directory of Open Access Journals (Sweden)

Juan C Ramírez

2017-12-01

Full Text Available Trypanosoma cruzi has been subdivided into seven Discrete Typing Units (DTUs, TcI-TcVI and Tcbat. Two major evolutionary models have been proposed to explain the origin of hybrid lineages, but while it is widely accepted that TcV and TcVI are the result of genetic exchange between TcII and TcIII strains, the origin of TcIII and TcIV is still a matter of debate. T. cruzi satellite DNA (SatDNA, comprised of 195 bp units organized in tandem repeats, from both TcV and TcVI stocks were found to have SatDNA copies type TcI and TcII; whereas contradictory results were observed for TcIII stocks and no TcIV sequence has been analyzed yet. Herein, we have gone deeper into this matter analyzing 335 distinct SatDNA sequences from 19 T. cruzi stocks representative of DTUs TcI-TcVI for phylogenetic inference. Bayesian phylogenetic tree showed that all sequences were grouped in three major clusters, which corresponded to sequences from DTUs TcI/III, TcII and TcIV; whereas TcV and TcVI stocks had two sets of sequences distributed into TcI/III and TcII clusters. As expected, the lowest genetic distances were found between TcI and TcIII, and between TcV and TcVI sequences; whereas the highest ones were observed between TcII and TcI/III, and among TcIV sequences and those from the remaining DTUs. In addition, signature patterns associated to specific T. cruzi lineages were identified and new primers that improved SatDNA-based qPCR sensitivity were designed. Our findings support the theory that TcIII is not the result of a hybridization event between TcI and TcII, and that TcIV had an independent origin from the other DTUs, contributing to clarifying the evolutionary history of T. cruzi lineages. Moreover, this work opens the possibility of typing samples from Chagas disease patients with low parasitic loads and improving molecular diagnostic methods of T. cruzi infection based on SatDNA sequence amplification.

New insights into Trypanosoma cruzi evolution, genotyping and molecular diagnostics from satellite DNA sequence analysis.

Science.gov (United States)

Ramírez, Juan C; Torres, Carolina; Curto, María de Los A; Schijman, Alejandro G

2017-12-01

Trypanosoma cruzi has been subdivided into seven Discrete Typing Units (DTUs), TcI-TcVI and Tcbat. Two major evolutionary models have been proposed to explain the origin of hybrid lineages, but while it is widely accepted that TcV and TcVI are the result of genetic exchange between TcII and TcIII strains, the origin of TcIII and TcIV is still a matter of debate. T. cruzi satellite DNA (SatDNA), comprised of 195 bp units organized in tandem repeats, from both TcV and TcVI stocks were found to have SatDNA copies type TcI and TcII; whereas contradictory results were observed for TcIII stocks and no TcIV sequence has been analyzed yet. Herein, we have gone deeper into this matter analyzing 335 distinct SatDNA sequences from 19 T. cruzi stocks representative of DTUs TcI-TcVI for phylogenetic inference. Bayesian phylogenetic tree showed that all sequences were grouped in three major clusters, which corresponded to sequences from DTUs TcI/III, TcII and TcIV; whereas TcV and TcVI stocks had two sets of sequences distributed into TcI/III and TcII clusters. As expected, the lowest genetic distances were found between TcI and TcIII, and between TcV and TcVI sequences; whereas the highest ones were observed between TcII and TcI/III, and among TcIV sequences and those from the remaining DTUs. In addition, signature patterns associated to specific T. cruzi lineages were identified and new primers that improved SatDNA-based qPCR sensitivity were designed. Our findings support the theory that TcIII is not the result of a hybridization event between TcI and TcII, and that TcIV had an independent origin from the other DTUs, contributing to clarifying the evolutionary history of T. cruzi lineages. Moreover, this work opens the possibility of typing samples from Chagas disease patients with low parasitic loads and improving molecular diagnostic methods of T. cruzi infection based on SatDNA sequence amplification.

Oxidation of ascorbic acid by a (salen)ruthenium(VI) nitrido complex in aqueous solution.

Science.gov (United States)

Wang, Qian; Man, Wai-Lun; Lam, William W Y; Lau, Tai-Chu

2014-12-25

The oxidation of ascorbic acid (H2A) by [Ru(VI)(N)(L)(MeOH)](+) in aqueous acidic solutions has the following stoichiometry: 2[Ru(VI)(N)] + 3H2A → 2[Ru(III)(NH2-HA)](+) + A. Mechanisms involving HAT/N-rebound at low pH (≤2) and nucleophilic attack at the nitride at high pH (≥5) are proposed.

Strain effects in the common-cation II-VI heterostructures: case of ZnS/ZnSe superlattices

CERN Document Server

Tit, N

2003-01-01

The electronic band-structures of the strained-layer ZnS/ZnSe (001) superlattices (SLs) have been investigated using the sp sup 3 s* tight-binding method, which includes the strain and spin-orbit effects. The SL band-structures are studied versus the biaxial strain, layer thickness, and band offsets. The results suggest that the common-cation II-VI heterojunction exhibit a vanishingly small conduction-band offset (CBO). It is shown that the SL valence-band top state is always a heavy-hole localized within ZnSe slabs; whereas the conduction-band edge state (electron) is sensitive to the biaxial strain (or VBO). To assess the strain effects, we considered three differently strained SLs corresponding to the three substrates: (i) ZnSe; (ii) ZnS sub 0 sub . sub 5 Se sub 0 sub . sub 5; and (iii) ZnS. The results show that all the studied SLs are of type-I except those strained to ZnS (case iii), that may exhibit type-I to type-II transition. One striking result obtained here is the existence of a critical VBO (V su...

In Situ Bioreduction of Uranium (VI) to Submicromolar Levels and Reoxidation by Dissolved Oxygen

International Nuclear Information System (INIS)

Wu, Weimin; Carley, Jack M.; Luo, Jian; Ginder-Vogel, Matthew A.; Cardenas, Erick; Leigh, Mary Beth; Hwang, Chaichi; Kelly, Shelly D.; Ruan, Chuanmin; Wu, Liyou; Van Nostrand, Joy; Gentry, Terry J.; Lowe, Kenneth Alan; Mehlhorn, Tonia L.; Carroll, Sue L.; Luo, Wensui; Fields, Matthew Wayne; Gu, Baohua; Watson, David B.; Kemner, Kenneth M.; Marsh, Terence; Tiedje, James; Zhou, Jizhong; Fendorf, Scott; Kitanidis, Peter K.; Jardine, Philip M.; Criddle, Craig

2007-01-01

Groundwater within Area 3 of the U.S. Department of Energy (DOE) Environmental Remediation Sciences Program (ERSP) Field Research Center at Oak Ridge, TN (ORFRC) contains up to 135 (micro)M uranium as U(VI). Through a series of experiments at a pilot scale test facility, we explored the lower limits of groundwater U(VI) that can be achieved by in-situ biostimulation and the effects of dissolved oxygen on immobilized uranium. Weekly 2 day additions of ethanol over a 2-year period stimulated growth of denitrifying, Fe(III)-reducing, and sulfate-reducing bacteria, and immobilization of uranium as U(IV), with dissolved uranium concentrations decreasing to low levels. Following sulfite addition to remove dissolved oxygen, aqueous U(VI) concentrations fell below the U.S. Environmental Protection Agency maximum contaminant limit (MCL) for drinking water ( -1 or 0.126 (micro)M). Under anaerobic conditions, these low concentrations were stable, even in the absence of added ethanol. However, when sulfite additions stopped, and dissolved oxygen (4.0-5.5 mg L -1 ) entered the injection well, spatially variable changes in aqueous U(VI) occurred over a 60 day period, with concentrations increasing rapidly from <0.13 to 2.0 (micro)M at a multilevel sampling (MLS) well located close to the injection well, but changing little at an MLS well located further away. Resumption of ethanol addition restored reduction of Fe(III), sulfate, and U(VI) within 36 h. After 2 years of ethanol addition, X-ray absorption near-edge structure spectroscopy (XANES) analyses indicated that U(IV) comprised 60-80% of the total uranium in sediment samples. At the completion of the project (day 1260), U concentrations in MLS wells were less than 0.1 (micro)M. The microbial community at MLS wells with low U(VI) contained bacteria that are known to reduce uranium, including Desulfovibrio spp. and Geobacter spp., in both sediment and groundwater. The dominant Fe(III)-reducing species were Geothrix spp

Analysis of gold(I/III)-complexes by HPLC-ICP-MS demonstrates gold(III) stability in surface waters.

Science.gov (United States)

Ta, Christine; Reith, Frank; Brugger, Joël; Pring, Allan; Lenehan, Claire E

2014-05-20

Understanding the form in which gold is transported in surface- and groundwaters underpins our understanding of gold dispersion and (bio)geochemical cycling. Yet, to date, there are no direct techniques capable of identifying the oxidation state and complexation of gold in natural waters. We present a reversed phase ion-pairing HPLC-ICP-MS method for the separation and determination of aqueous gold(III)-chloro-hydroxyl, gold(III)-bromo-hydroxyl, gold(I)-thiosulfate, and gold(I)-cyanide complexes. Detection limits for the gold species range from 0.05 to 0.30 μg L(-1). The [Au(CN)2](-) gold cyanide complex was detected in five of six waters from tailings and adjacent monitoring bores of working gold mines. Contrary to thermodynamic predictions, evidence was obtained for the existence of Au(III)-complexes in circumneutral, hypersaline waters of a natural lake overlying a gold deposit in Western Australia. This first direct evidence for the existence and stability of Au(III)-complexes in natural surface waters suggests that Au(III)-complexes may be important for the transport and biogeochemical cycling of gold in surface environments. Overall, these results show that near-μg L(-1) enrichments of Au in environmental waters result from metastable ligands (e.g., CN(-)) as well as kinetically controlled redox processes leading to the stability of highly soluble Au(III)-complexes.

Monophasic action potentials and activation recovery intervals as measures of ventricular action potential duration: experimental evidence to resolve some controversies

NARCIS (Netherlands)

Coronel, Ruben; de Bakker, Jacques M. T.; Wilms-Schopman, Francien J. G.; Opthof, Tobias; Linnenbank, André C.; Belterman, Charly N.; Janse, Michiel J.

2006-01-01

BACKGROUND: Activation recovery intervals (ARIs) and monophasic action potential (MAP) duration are used as measures of action potential duration in beating hearts. However, controversies exist concerning the correct way to record MAPs or calculate ARIs. We have addressed these issues

Monophasic teratoma of the ovarian remnant in a bitch.

Science.gov (United States)

Rota, A; Tursi, M; Zabarino, S; Appino, S

2013-04-01

An exploratory laparotomy on a mixed-breed bitch of an estimated age of 5 years revealed that she had undergone ovariectomy in the past, but a cystic structure was present in the area of the right ovary and a whitish mass, approximately 3 cm in diameter, in the area of the left ovary. These structures were removed together with an apparently normal uterus. Histological examination of the cyst showed a thin layer of connective tissue, while the left ovarian mass revealed ovarian tissue and highly differentiated nervous tissue, confirmed through immunohistochemistry. A presumptive diagnosis of mature ovarian teratoma was made. Although teratomas generally contain recognizable elements from more than one of the three germ cell layers, they can also be monophasic, when there is only one germ layer component. Ovarian teratomas are rare in the dog and never before have been reported in an ovarian fragment. © 2012 Blackwell Verlag GmbH.

Chromium(III) release from chromium‐tanned leather elicits allergic contact dermatitis: a use test study

Science.gov (United States)

Erfani, Behnaz; Matura, Mihály; Lidén, Carola

2018-01-01

Summary Background Chromium (Cr) is a common skin sensitizer. The use of Cr(VI) in leather is restricted in the EU, but that of Cr(III) is not. Objectives To assess whether prolonged exposure to Cr‐tanned leather with mainly Cr(III) release may elicit allergic contact dermatitis in Cr‐allergic individuals. Method Ten Cr‐allergic subjects and 22 controls were patch tested with serial dilutions of Cr(III) and Cr(VI), and with leather samples. They then conducted a use test with a Cr‐tanned and a Cr‐free leather bracelet over a period of 3 weeks, for 12 h per day. Cr deposited on the skin from the bracelets was measured in the controls, and the diphenylcarbazide test for Cr(VI) and extraction tests for Cr(III) and Cr(VI) were conducted for the different leathers. Results Four of 10 Cr‐allergic subjects developed positive reactions to the Cr‐tanned bracelet within 7–21 days, whereas only 1 of 10 had a positive patch test reaction to this leather. Cr released from the Cr‐tanned leather was most probably entirely Cr(III), with a quantifiable amount being deposited on the skin. Conclusions This study strongly suggests that prolonged and repeated exposure to Cr‐tanned leather with mainly Cr(III) release is capable of eliciting allergic contact dermatitis in Cr‐allergic individuals. PMID:29322530

Study on competitive adsorption mechanism among oxyacid-type heavy metals in co-existing system: Removal of aqueous As(V), Cr(III) and As(III) using magnetic iron oxide nanoparticles (MIONPs) as adsorbents

Science.gov (United States)

Lin, Sen; Lian, Cheng; Xu, Meng; Zhang, Wei; Liu, Lili; Lin, Kuangfei

2017-11-01

The adsorption and co-adsorption of As(V), Cr(VI) and As(III) onto the magnetic iron oxide nanoparticles (MIONPs) surface were investigated comprehensively to clarify the competitive processes. The results reflected that the MIONPs had remarkable preferential adsorption to As(V) compared with Cr(VI) and As(III). And it was determined, relying on the analysis of heavy metals variations on the MIONPs surface at different co-adsorption stages using FTIR and XPS, that the inner-sphere complexation made vital contribution to the preferential adsorption for As(V), corresponding with the replacement experiments where As(V) could grab extensively active sites on the MIONPs pre-occupied by As(III) or Cr(V) uniaxially. The desorption processes displayed that the strongest affinity between the MIONPs and As(V) where As(III) and Cr(VI) were more inclined to wash out. It is wish to provide a helpful direction with this study for the wastewater treatment involving multiple oxyacid-type heavy metals using MIONPs as adsorbents.

Uranium determination by spectrophotometry, in chloride solutions, using titanium (III) as reducer; Determinacao de uranio por espectrofotometria, em solucoes cloridricas, utilizando titanio (III) como redutor

Energy Technology Data Exchange (ETDEWEB)

Bastos, E T.R.; Bastos, M B.R.

1986-08-01

A simple method for determining uranium in uranium (VI) solutions with the presence of uranium (IV), iron (II), and titanium (IV) in chloridic solution is described. The method comprises in uranium (VI) reduction with titanium (III), acidity adjustment and uranium (IV) spectrophotometry in hydrochloric acid 2 M. (C.G.C.).

Evaluation of surface detail reproduction, dimensional stability and gypsum compatibility of monophase polyvinyl-siloxane and polyether elastomeric impression materials under dry and moist conditions.

Science.gov (United States)

Vadapalli, Sriharsha Babu; Atluri, Kaleswararao; Putcha, Madhu Sudhan; Kondreddi, Sirisha; Kumar, N Suman; Tadi, Durga Prasad

2016-01-01

This in vitro study was designed to compare polyvinyl-siloxane (PVS) monophase and polyether (PE) monophase materials under dry and moist conditions for properties such as surface detail reproduction, dimensional stability, and gypsum compatibility. Surface detail reproduction was evaluated using two criteria. Dimensional stability was evaluated according to American Dental Association (ADA) specification no. 19. Gypsum compatibility was assessed by two criteria. All the samples were evaluated, and the data obtained were analyzed by a two-way analysis of variance (ANOVA) and Pearson's Chi-square tests. When surface detail reproduction was evaluated with modification of ADA specification no. 19, both the groups under the two conditions showed no significant difference statistically. When evaluated macroscopically both the groups showed statistically significant difference. Results for dimensional stability showed that the deviation from standard was significant among the two groups, where Aquasil group showed significantly more deviation compared to Impregum group (P < 0.001). Two conditions also showed significant difference, with moist conditions showing significantly more deviation compared to dry condition (P < 0.001). The results of gypsum compatibility when evaluated with modification of ADA specification no. 19 and by giving grades to the casts for both the groups and under two conditions showed no significant difference statistically. Regarding dimensional stability, both impregum and aquasil performed better in dry condition than in moist; impregum performed better than aquasil in both the conditions. When tested for surface detail reproduction according to ADA specification, under dry and moist conditions both of them performed almost equally. When tested according to macroscopic evaluation, impregum and aquasil performed significantly better in dry condition compared to moist condition. In dry condition, both the materials performed almost equally. In

Scientific conference on inorganic chemistry and radiochemistry devoted to centenary from birthday of academician V.I. Spitsyn. Program of conference and summary of reports

International Nuclear Information System (INIS)

2002-01-01

Program and summaries of reports of the Scientific conference on inorganic chemistry and radiochemistry devoted to the centenary from the birthday of academician V.I. Spitsyn are presented. The conference took place at the Chemical department of the Moscow State University named for M.V. Lomonosov 17 - 18 April, 2002. Part of the reports was devoted to the work of academician V.I. Spitsyn, his investigations into radiochemistry and radiation chemistry. Scientific explorations in the fields of solid chemistry, inorganic and coordination chemistry, radiochemistry and chemical technology are discussed [ru

Hvad skal vi med Etisk Råd?

DEFF Research Database (Denmark)

Ploug, Thomas; Gjerris, Mickey

2012-01-01

Det Etiske Råd har for os at se en væsentlig rolle at spille i et åbent og demokratisk samfund som det danske. Vi skal være med til at skabe grobund for de værdidiskussioner, som skal forme fremtidens samfund. Etik er at være i dialog – ikke at kaste med mudder.......Det Etiske Råd har for os at se en væsentlig rolle at spille i et åbent og demokratisk samfund som det danske. Vi skal være med til at skabe grobund for de værdidiskussioner, som skal forme fremtidens samfund. Etik er at være i dialog – ikke at kaste med mudder....

Self-esteem in adolescents with Angle Class I, II and III malocclusion in a Peruvian sample.

Science.gov (United States)

Florián-Vargas, Karla; Honores, Marcos J Carruitero; Bernabé, Eduardo; Flores-Mir, Carlos

2016-01-01

To compare self-esteem scores in 12 to 16-year-old adolescents with different Angle malocclusion types in a Peruvian sample. A cross-sectional study was conducted in a sample of 276 adolescents (159, 52 and 65 with Angle Class I, II and III malocclusions, respectively) from Trujillo, Peru. Participants were asked to complete the Rosenberg Self-Esteem Scale (RSES) and were also clinically examined, so as to have Angle malocclusion classification determined. Analysis of covariance (ANCOVA) was used to compare RSES scores among adolescents with Class I, II and III malocclusions, with participants' demographic factors being controlled. Mean RSES scores for adolescents with Class I, II and III malocclusions were 20.47 ± 3.96, 21.96 ± 3.27 and 21.26 ± 4.81, respectively. The ANCOVA test showed that adolescents with Class II malocclusion had a significantly higher RSES score than those with Class I malocclusion, but there were no differences between other malocclusion groups. Supplemental analysis suggested that only those with Class II, Division 2 malocclusion might have greater self-esteem when compared to adolescents with Class I malocclusion. This study shows that, in general, self-esteem did not vary according to adolescents' malocclusion in the sample studied. Surprisingly, only adolescents with Class II malocclusion, particularly Class II, Division 2, reported better self-esteem than those with Class I malocclusion. A more detailed analysis assessing the impact of anterior occlusal features should be conducted.

ENDF-201, ENDF/B-VI summary documentation supplement 1, ENDF/HE-VI summary documentation

International Nuclear Information System (INIS)

McLane, V.

1996-12-01

The National Nuclear Data Center (NNDC) provides coordination for and serves as the secretariat to the Cross Section Evaluation Working Group (CSWEG). CSEWG is responsible for the oversight of the ENDF/B Evaluated Nuclear Data File. All data are checked and reviewed by CSEWG, and the file is maintained at the NNDC. For a description of the ENDF/B-VI file, see the ENDF-102 Data Formats and Procedures for the Evaluated Nuclear Data File ENDF-6. The purpose of this addendum to the ENDF/B-VI Summary Documentation is to provide documentation of Releases 1, 2, 3, and 4 for the ENDF/B-VI and ENDF/HE-VI evaluated nuclear data libraries. These releases contain many new and revised evaluations for the neutron, photo-atomic interaction, radioactive decay data, spontaneous fission product yield, neutron-induced fission product yield, thermal neutron scattering, proton, deuteron, and triton sublibraries. The summaries have been extracted mainly from the ENDF/B-VI File 1 comments (MT = 451), which have been checked, edited, and may also include supplementary information. Some summaries have been provided by the evaluators in electronic format, while others are extracted from reports on the evaluations. All references have been checked and corrected, or updated where appropriate. A list of the laboratories which have contributed evaluations used in ENDF/B-VI is given

ENDF-201, ENDF/B-VI summary documentation supplement 1, ENDF/HE-VI summary documentation

Energy Technology Data Exchange (ETDEWEB)

McLane, V.

1996-12-01

The National Nuclear Data Center (NNDC) provides coordination for and serves as the secretariat to the Cross Section Evaluation Working Group (CSWEG). CSEWG is responsible for the oversight of the ENDF/B Evaluated Nuclear Data File. All data are checked and reviewed by CSEWG, and the file is maintained at the NNDC. For a description of the ENDF/B-VI file, see the ENDF-102 Data Formats and Procedures for the Evaluated Nuclear Data File ENDF-6. The purpose of this addendum to the ENDF/B-VI Summary Documentation is to provide documentation of Releases 1, 2, 3, and 4 for the ENDF/B-VI and ENDF/HE-VI evaluated nuclear data libraries. These releases contain many new and revised evaluations for the neutron, photo-atomic interaction, radioactive decay data, spontaneous fission product yield, neutron-induced fission product yield, thermal neutron scattering, proton, deuteron, and triton sublibraries. The summaries have been extracted mainly from the ENDF/B-VI File 1 comments (MT = 451), which have been checked, edited, and may also include supplementary information. Some summaries have been provided by the evaluators in electronic format, while others are extracted from reports on the evaluations. All references have been checked and corrected, or updated where appropriate. A list of the laboratories which have contributed evaluations used in ENDF/B-VI is given.

Biological detoxification of Cr(VI) using wood-husk immobilized Acinetobacter haemolyticus

International Nuclear Information System (INIS)

Zakaria, Zainul Akmar; Zakaria, Zainoha; Surif, Salmijah; Ahmad, Wan Azlina

2007-01-01

Acinetobacter haemolyticus, a Gram-negative aerobic locally isolated bacterium, immobilized on wood-husk showed the ability to detoxify Cr(VI) to Cr(III). Wood-husk, a natural cellulose-based support material, packed in an upward-flow column was used as support material for bacterial attachment. Around 97% of the Cr(VI) in wastewater containing 15 mg L -1 of Cr(VI) was reduced at a flow rate of 8.0 mL min -1 . The wastewater containing Cr(VI) was added with liquid pineapple wastewater as nutrient source for the bacteria. Electron microscopic examinations of the wood-husk after 42 days of column operation showed gradual colonization of the wood-husk by bacterial biofilm. The use of 0.1% (v/v) formaldehyde as a disinfecting agent inhibited growth of bacteria present in the final wastewater discharge. This finding is important in view of the ethical code regarding possible introduction of exogenous bacterial species into the environment

Biological detoxification of Cr(VI) using wood-husk immobilized Acinetobacter haemolyticus

Energy Technology Data Exchange (ETDEWEB)

Zakaria, Zainul Akmar; Zakaria, Zainoha [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Surif, Salmijah [Department of Environmental Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Ahmad, Wan Azlina [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia)], E-mail: azlina@kimia.fs.utm.my

2007-09-05

Acinetobacter haemolyticus, a Gram-negative aerobic locally isolated bacterium, immobilized on wood-husk showed the ability to detoxify Cr(VI) to Cr(III). Wood-husk, a natural cellulose-based support material, packed in an upward-flow column was used as support material for bacterial attachment. Around 97% of the Cr(VI) in wastewater containing 15 mg L{sup -1} of Cr(VI) was reduced at a flow rate of 8.0 mL min{sup -1}. The wastewater containing Cr(VI) was added with liquid pineapple wastewater as nutrient source for the bacteria. Electron microscopic examinations of the wood-husk after 42 days of column operation showed gradual colonization of the wood-husk by bacterial biofilm. The use of 0.1% (v/v) formaldehyde as a disinfecting agent inhibited growth of bacteria present in the final wastewater discharge. This finding is important in view of the ethical code regarding possible introduction of exogenous bacterial species into the environment.

Escuelas primarias en alemania i en prusia

OpenAIRE

Universidad Nacional, Colombia

2009-01-01

Catecismo del método de enseñanza. I.- Instrucción objetiva, por Diesterweg. II.- Enseñanza de lectura, por Honcamp. III.- La aritmética, por Diesterweg. IV.- Geometría, por Diesterweg. V.- Historia natural, por Hintze. VI.- Física, por Diesterweg. VII.- Astronomía, por Diesterweg. VIII.- Geografía, por Abbenrode. IX.- Historia, por Abbenrode.

Elaborations of Institute of Chemistry by name V.I. Nikitin-to the industry (by the example of aluminium plant)

International Nuclear Information System (INIS)

Mirsaidov, U.M.

2002-01-01

In this monograph elaborations of sciences of Institute of Chemistry by name V.I. Nikitin for country needs was systematized . Special attention is devote to complex wastes reprocessing of aluminium plant in Tajikistan. This book mean to scientists and engineer-technical employees

A first-principles study of group IV and VI atoms doped blue phosphorene

Science.gov (United States)

Bai, Ruimin; Chen, Zheng; Gou, Manman; Zhang, Yixin

2018-02-01

Using first-principles calculations, we have systematically investigated the structural, electronic and magnetic properties of blue phosphorene doped by group IV and VI atoms, including C, Si, Ge, Sn, O, S, Se and Te. All the doped systems are energetically stable. Only C, Si, Ge and O-substituted systems show the characteristics of spin polarization and the magnetic moments are all 1.0 μB. Moreover, we found that C, Si, Ge and O doped systems are indirect bandgap semiconductors, while Sn, S, Se and Te doped systems present metallic property. These results show that blue phosphorene can be used prospectively in optoelectronic and spintronic devices.

Viñales Taxonomic Characterization and trophic groups of two communities of birds associated to semideciduos forests and vegetation of Pine-oak of the paths «Marvels of Viñales» and «Valley Ancón» in Viñales National Park

Directory of Open Access Journals (Sweden)

Miguel Cué Rivero

2015-06-01

Full Text Available The present work was carried out in the months of February to April 2009 in the semideciduos forest «Marvels of Viñales» and the formation pine-encino of the «Valley Ancón» of the Viñales National Park and it pursued as main objective to characterize the taxonomic composition and tropic groups tof two communities of birds associated to semideciduos forest and pine oak vegetation from both -. The method of circular parcels of fixed radio was used in 30 points of counts separated to 150 m one of another. There were detected a total of 44 species of birds (in the semideciduo and 42 in pine-oak contained in 9 orders and 18 families. They registered 23 trophic groups with prevalence of Insectivorous. The communities of birds of the formation of semideciduo forest of the path «Marvels of Viñales» and of the forest of pine oak of «Valley Ancón» presented differences in its taxonomic composition The communities of birds of both vegetable formations showed differences as for their trophiccomposition but so much in one as in other majority of birds consumers of insects and grains was observed.

Crystal structure of dilead(II oxochromate(VI oxotellurate(IV

Directory of Open Access Journals (Sweden)

Matthias Weil

2017-06-01

Full Text Available Reaction of chromium(III precursors with TeO2 in PbF2/PbO melts in air led to oxidation of chromium(III to chromium(VI, whereas tellurium remained its oxidation state of IV. In the resulting title compound, Pb2(CrO4(TeO3, the two types of anions are isolated from each other, hence a double salt is formed. The two independent Pb2+ cations exhibit coordination number nine under formation of very distorted coordination polyhedra [bond-length range = 2.363 (6–3.276 (7 Å]. The oxochromate(VI and oxotellurate(IV anions have tetrahedral and trigonal–pyramidal configurations, respectively. In the crystal structure, (001 layers of metal cations alternate with layers of TeO32− and CrO42− anions along [001], forming a three-dimensional framework structure. Pb2(CrO4(TeO3 is isotypic with its sulfate analogue Pb2(SO4(TeO3 and is comparatively discussed.

Treatment of hexavalent chromium Cr (VI) in tanning effluent

International Nuclear Information System (INIS)

Ahmed, I.; Ali, S.

1999-01-01

Most common chemical used in chrome tanning is basic chromium sulphate (BCS). Manufacturing of BCS involves many steps producing liquid waste. Waste generated at every stage contains Cr (VI), which must be reduced to Cr (III) before being disposed to the environment. Different methods were studied for the reduction of toxic Cr (III). Pickle liquor (waste of electroplating industry) can also be used for the reduction of hexavalent chromium Cr (vi) along with other reducing materials / chemicals. In an electroplating process metal is treated with HCl or H/sub 2/SO/sub 4/ to remove scales and rust, the pickled items are then washed with water, washing contains FeCl/sub 2/ or fees/sub 4/ respectively called pickle liquor. During waste treatment pH adjustment to 6.0 - 9.0 and settling the sludge, is discharged to the lagoon. The sludge obtained is dried and disposed off in landfills. Other reducing agents like sodium bisulphite and sulfur dioxide were also studied, but pickle liquor was found to be more effective and economical. (author)

The Russia Corporate Governance Manual : Part I. Corporate Governance Introduced

OpenAIRE

International Finance Corporation; U.S. Department of Commerce

2004-01-01

The Russia corporate governance manual has been divided into and is published in six parts: (i) corporate governance introduced; (ii) good board practices; (iii) shareholder rights; (iv) information disclosure and transparency; (v) special focus section; and (vi) annexes model corporate governance documents. The first four parts contain chapters that focus on core corporate governance issu...

Comparison of Glucosamine-Chondroitin Sulfate with and without Methylsulfonylmethane in Grade I-II Knee Osteoarthritis: A Double Blind Randomized Controlled Trial.