Removal of Cr(VI) by surfactant modified Auricularia auricula spent substrate: biosorption condition and mechanism.

PubMed

Dong, Liying; Jin, Yu; Song, Tao; Liang, Jinsong; Bai, Xin; Yu, Sumei; Teng, Chunying; Wang, Xin; Qu, Juanjuan; Huang, Xiaomei

2017-07-01

Auricularia auricula spent substrate (AASS) modified by didodecyldimethylammonium bromide(DDAB) was used as adsorbent to remove Cr(VI) from aqueous solution. Based on a single-factor experiment and response surface methodology, the optimal conditions were adsorbent dosage of 1.5 g/L, pH value of 4.0, initial Cr(VI) concentration of 19 mg/L, temperature of 25 °C, biosorption time of 120 min, rotational speed of 150 r/min, respectively, under which biosorption capacity could reach 12.16 mg/g compared with unmodified AASS (6.058 mg/g). DDAB modification could enlarge the specific surface area and porous diameter of the adsorbents, and supply hydrophilic and hydrophobic groups capable of adsorbing at the interfaces. In addition, DDAB increased ionic exchange and complex formation demonstrated by variations of elemental contents, shifts of carboxyl, amine groups, hydroxyl, alkyl chains, and phosphate groups as well as the crystal structure of the Cr-O compounds. Variations of peaks and energy in XPS analysis also testified the reduction of Cr(VI) to Cr(III).The biosorption behavior of modified AASS was in line with Langmuir and Freundlich isotherm equation. The final regeneration efficiency was 62.33% after three biosorption-desorption cycles. Apparently, DDBA is a eximious modifier and DDBA-modified AASS was very efficient for Cr(VI) removal.

Organic and Aqueous Redox Speciation of Cu(III) Periodate Oxidized Transuranium Actinides

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

McCann, Kevin; Sinkov, Sergey I.; Lumetta, Gregg J.

A hexavalent group actinide separation process could streamline used nuclear fuel recycle and waste management. The limiting factor to such a process compatible with current fuel dissolution practices is obtaining and maintaining hexavalent Am, in molar nitric acid due to the high reduction potential of the Am(VI)/Am(III) couple (1.68 V vs SCE). Two strong oxidants, sodium bismuthate and Cu(III) periodate, have demonstrated quantitative oxidation of Am under molar acid conditions and better than 50% recovery by diamyl amylphosphonate (DAAP) is possible under these same conditions. This work considers the use of Cu(III) periodate to oxidize Np(V) to Np(VI) and Pu(IV)more » to Pu(VI) and recover these elements by extraction with DAAP. A metal:oxidant ratio of 1:1.2 and 1:3 was necessary to quantitatively oxidize Np(V) and Pu(IV), respectively, to the hexavalent state. Extraction of hexavalent Np, Pu, and Am by 1 M DAAP in n-dodecane was measured using UV-Vis [Pu(VI), Am (VI)] and NIR [Np(VI)]. Distribution values of Am(VI) were found to match previous tracer level studies. The organic phase spectra of Np, Pu, and Am are presented and molar absorptivities are calculated for characteristic peaks. Hexavalent Pu was found to be stable in the organic phase while Np(VI) showed some reduction to Np(V) and Am was present as Am(III), Am(V), and Am(VI) species in aqueous and organic phases during the extraction experiments. These results demonstrate, for the first time, the ability to recover macroscopic amounts of americium that would be present during fuel reprocessing and are the first characterization of Am organic phase oxidation state speciation relevant to a hexavalent group actinide separation process under acidic conditions.« less

Lattice thermal expansion for normal tetrahedral compound semiconductors

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

Omar, M.S.

2007-02-15

The cubic root of the deviation of the lattice thermal expansion from that of the expected value of diamond for group IV semiconductors, binary compounds of III-V and II-VI, as well as several ternary compounds from groups I-III-VI{sub 2}, II-IV-V{sub 2} and I-IV{sub 2}V{sub 3} semiconductors versus their bonding length are given straight lines. Their slopes were found to be 0.0256, 0.0210, 0.0170, 0.0259, 0.0196, and 0.02840 for the groups above, respectively. Depending on the valence electrons of the elements forming these groups, a formula was found to correlate all the values of the slopes mentioned above to that ofmore » group IV. This new formula which depends on the melting point and the bonding length as well as the number of valence electrons for the elements forming the compounds, will gives best calculated values for lattice thermal expansion for all compounds forming the groups mentioned above. An empirical relation is also found between the mean ionicity of the compounds forming the groups and their slopes mentioned above and that gave the mean ionicity for the compound CuGe{sub 2}P{sub 3} in the range of 0.442.« less

Combined distillation and normal freezing to purify elements of groups II and VI

NASA Technical Reports Server (NTRS)

Holland, L. R.

1984-01-01

A practical system and its application to the purification of Te and Cd is described. Single crystals are grown directly in vitreous silica ampoules subsequently used for sealed Bridgman growth of (Hg-Cd)Te. The system also prepares the ampoules by heating in high vacuum. Purification of the elements is by the combined effect of distillation and normal freezing. Transport and segregation are discussed.

Fabrication of hierarchical core-shell polydopamine@MgAl-LDHs composites for the efficient enrichment of radionuclides

NASA Astrophysics Data System (ADS)

Zhu, Kairuo; Lu, Songhua; Gao, Yang; Zhang, Rui; Tan, Xiaoli; Chen, Changlun

2017-02-01

Novel hierarchical core/shell structured polydopamine@MgAl-layered double hydroxides (PDA@MgAl-LDHs) composites involving MgAl-layered double hydroxide shells and PDA cores were fabricated thought one-pot coprecipitation assembly and methodically characterized by X-ray diffraction, Fourier transformed infrared spectroscopy, scanning/transmission electron microscopy, selected area electron diffraction, elemental mapping, thermogravimetric analysis and X-ray photoelectron spectroscopy technologies. U(VI) and Eu(III) sorption experiments showed that the PDA@MgAl-LDHs exhibited higher sorption ability with a maximum sorption capacity of 142.86 and 76.02 mg/g at 298 K and pH 4.5, respectively. More importantly, according to XPS analyses, U(VI) and Eu(III) were sorbed on PDA@MgAl-LDHs via oxygen-containing functional groups, and the chemical affinity of U(VI) by oxygen-containing functional groups is higher than that of Eu(III). These observations show great expectations in the enrichment of radionuclides from aquatic environments by PDA@MgAl-LDHs.

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

Ünlü, Hilmi, E-mail: hunlu@itu.edu.tr

We propose a non-orthogonal sp{sup 3} hybrid bond orbital model to determine the electronic properties of semiconductor heterostructures. The model considers the non-orthogonality of sp{sup 3} hybrid states of nearest neighboring adjacent atoms using the intra-atomic Coulomb interactions corrected Hartree-Fock atomic energies and metallic contribution to calculate the valence band width energies of group IV elemental and group III-V and II-VI compound semiconductors without any adjustable parameter.

Structural and electronic properties of monolayer group III monochalcogenides

NASA Astrophysics Data System (ADS)

Demirci, S.; Avazlı, N.; Durgun, E.; Cahangirov, S.

2017-03-01

We investigate the structural, mechanical, and electronic properties of the two-dimensional hexagonal structure of group III-VI binary monolayers, M X (M =B , Al, Ga, In and X =O , S, Se, Te) using first-principles calculations based on the density functional theory. The structural optimization calculations and phonon spectrum analysis indicate that all of the 16 possible binary compounds are thermally stable. In-plane stiffness values cover a range depending on the element types and can be as high as that of graphene, while the calculated bending rigidity is found to be an order of magnitude higher than that of graphene. The obtained electronic band structures show that M X monolayers are indirect band-gap semiconductors. The calculated band gaps span a wide optical spectrum from deep ultraviolet to near infrared. The electronic structure of oxides (M O ) is different from the rest because of the high electronegativity of oxygen atoms. The dispersions of the electronic band edges and the nature of bonding between atoms can also be correlated with electronegativities of constituent elements. The unique characteristics of group III-VI binary monolayers can be suitable for high-performance device applications in nanoelectronics and optics.

Using Generalized Annotated Programs to Solve Social Network Diffusion Optimization Problems

DTIC Science & Technology

2013-01-01

as follows: —Let kall be the k value for the SNDOP-ALL query and for each SNDOP query i, let ki be the k for that query. For each query i, set ki... kall − 1. —Number each element of vi ∈ V such that gI(vi) and V C(vi) are true. For the ith SNDOP query, let vi be the corresponding element of V —Let...vertices of S. PROOF. We set up |V | SNDOP-queries as follows: —Let kall be the k value for the SNDOP-ALL query and and for each SNDOP-query i, let ki be

Chromium distribution in shoots of macrophyte Callitriche cophocarpa Sendtn.

PubMed

Augustynowicz, Joanna; Wróbel, Paweł; Płachno, Bartosz J; Tylko, Grzegorz; Gajewski, Zbigniew; Węgrzynek, Dariusz

2014-06-01

The aim of the study was the analysis of Cr distribution in shoots of the macrophyte Callitriche cophocarpa by means of two X-ray-based techniques: micro X-ray fluorescence (μXRF) and electron probe X-ray microanalysis (EPXMA). Plants were treated with 100 μM (5.2 mg l(-1)) chromium solutions for 7 days. Cr was introduced independently at two speciations as Cr(III) and Cr(VI), known for their diverse physicochemical properties and different influence on living organisms. A comparative analysis of Cr(III)-treated plants by EPXMA and μXRF demonstrated high deposition of Cr in epidermal glands/hairs localized on leaves and stems of the plant shoots. Cr in Cr(III)-treated plants was recorded solely in glands/hairs, and the element was not present in any other structures. On the other hand, Cr in Cr(VI)-treated group of plants was rather found in vascular bundles. Moreover, the concentration of Cr in Cr(VI)-treated plants was significantly lower than in plants incubated in Cr(III) solution. The results obtained in this work suggest differences in chromium uptake, transport and accumulation dependent on the oxidative state of the element.

Increased Expression of Brain-Derived Neurotrophic Factor Transcripts I and VI, cAMP Response Element Binding, and Glucocorticoid Receptor in the Cortex of Patients with Temporal Lobe Epilepsy.

PubMed

Martínez-Levy, G A; Rocha, L; Rodríguez-Pineda, F; Alonso-Vanegas, M A; Nani, A; Buentello-García, R M; Briones-Velasco, M; San-Juan, D; Cienfuegos, J; Cruz-Fuentes, C S

2018-05-01

A body of evidence supports a relevant role of brain-derived neurotrophic factor (BDNF) in temporal lobe epilepsy (TLE). Magnetic resonance data reveal that the cerebral atrophy extends to regions that are functionally and anatomically connected with the hippocampus, especially the temporal cortex. We previously reported an increased expression of BDNF messenger for the exon VI in the hippocampus of temporal lobe epilepsy patients compared to an autopsy control group. Altered levels of this particular transcript were also associated with pre-surgical use of certain psychotropic. We extended here our analysis of transcripts I, II, IV, and VI to the temporal cortex since this cerebral region holds intrinsic communication with the hippocampus and is structurally affected in patients with TLE. We also assayed the cyclic adenosine monophosphate response element-binding (CREB) and glucocorticoid receptor (GR) genes as there is experimental evidence of changes in their expression associated with BDNF and epilepsy. TLE and pre-surgical pharmacological treatment were considered as the primary clinical independent variables. Transcripts BDNF I and BDNF VI increased in the temporal cortex of patients with pharmacoresistant TLE. The expression of CREB and GR expression follow the same direction. Pre-surgical use of selective serotonin reuptake inhibitors, carbamazepine (CBZ) and valproate (VPA), was associated with the differential expression of specific BDNF transcripts and CREB and GR genes. These changes could have functional implication in the plasticity mechanisms related to temporal lobe epilepsy.

Counterinsurgency Operations

DTIC Science & Technology

2009-10-05

AND SUBTITLE Counterinsurgency Operations 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e...VI-14  Voluntary Detainee Programs ......................................................................VI-14...Reintegration Program .....VI-22 iv JP 3-24 Table of Contents CHAPTER VII COMPONENT CONTRIBUTIONS TO COUNTERINSURGENCY  Joint Counterinsurgency

Tumoral Venous Invasion after Distal Pancreatectomy: A Risk Factor for Recurrence.

PubMed

Joliat, Gaëtan-Romain; Petermann, David; Demartines, Nicolas; Halkic, Nermin; Schäfer, Markus

2018-05-31

Few data exist on postoperative outcomes of patients with pancreatic body-tail malignancies and tumoral venous invasion (VI). This study aimed at comparing survival and recurrence rate (RR) after distal pancreatectomy for adenocarcinoma in patients with and without tumoral VI. All consecutive distal pancreatectomies (2000-2015) were collected. Demographics and peri- and postoperative data were recorded. Survivals were calculated using Kaplan-Meier curves. A total of 45 patients underwent distal pancreatectomies for malignancies, of which 33 patients had ductal adenocarcinomas and 2 had cystadenocarcinomas. Among these 35 adenocarcinomas, histological VI was found in 28 patients (80%). Characteristics and intraoperative data of patients with and without VI were similar. Complication rates were 15 of 28 (54%) in the VI group and 3 of 7 (43%) in the group without VI (p = 0.612). Five-year survival for the group with and without VI were 19 and 39% (p = 0.232), respectively. RR was 16 of 28 (57%) for the VI group and 1 of 7 (14%) for the group without VI (p = 0.042). VI did not have an effect on postoperative -complications. Survivals were similar in case of VI or not. On the contrary, RR was higher in the VI group. © 2018 S. Karger AG, Basel.

Integrated Conceptual Design of Joined-Wing SensorCraft Using Response Surface Models

DTIC Science & Technology

2006-11-01

vi Acknowledgements I would like to express my sincere appreciation to my thesis advisor, Dr. Robert Canfield for his guidance and...55 Raymer Approximate and Group Weights Sizing Methods....................................... 57 Finite Element Model Structural Weight...Empty Weight Fraction Equation ............................... 54 Figure 29 Response of Refined Weight to T/W and W/S Inputs for Model (2) Raymer ASW

Bulk dimensional nanocomposites for thermoelectric applications

DOEpatents

Nolas, George S

2014-06-24

Thermoelectric elements may be used for heat sensors, heat pumps, and thermoelectric generators. A quantum-dot or nano-scale grain size polycrystalline material the effects of size-quantization are present inside the nanocrystals. A thermoelectric element composed of densified Groups IV-VI material, such as calcogenide-based materials are doped with metal or chalcogenide to form interference barriers form along grains. The dopant used is either silver or sodium. These chalcogenide materials form nanoparticles of highly crystal grains, and may specifically be between 1- and 100 nm. The compound is densified by spark plasma sintering.

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

NASA Astrophysics Data System (ADS)

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.

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

PubMed

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

2017-07-03

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

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

PubMed

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 <0.4 mg kg(-1) limit established for Cr-VI toxicity in 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.

Rhenium-osmium systematics of calcium-aluminium-rich inclusions in carbonaceous chondrites

USGS Publications Warehouse

Becker, H.; Morgan, J.W.; Walker, R.J.; MacPherson, G.J.; Grossman, J.N.

2001-01-01

The Re-Os isotopic systematics of calcium-aluminium-rich inclusions (CAIs) in chondrites were investigated in order to shed light on the behavior of the Re-Os system in bulk chondrites, and to constrain the timing of chemical fractionation in primitive chondrites. CAIs with relatively unfractionated rare earth element (REE) patterns (groups I, III, V, VI) define a narrow range of 187Re/188Os (0.3764-0.4443) and 187Os/188Os (0.12599-0.12717), and high but variable Re and Os abundances (3209-41,820 ppb Os). In contrast, CAIs that show depletions in highly refractory elements and strongly fractionated REE patterns (group II) also show a much larger range in 187Re/188Os (0.409-0.535) and 187Os/188Os (0.12695-0.13770), and greater than an order of magnitude lower Re and Os abundances than other groups (e.g., 75.7-680.2 ppb Os). Sixteen bulk CAIs and CAI splits plot within analytical uncertainty of a 4558 Ga reference isochron, as is expected for materials of this antiquity. Eight samples, however, plot off the isochron. Several possible reasons for these deviations are discussed. Data for multiple splits of one CAI indicate that the nonisochronous behavior for at least this CAI is the result of Re-Os reequilibration at approximately 1.6 Ga. Thus, the most likely explanation for the deviations of most of the nonisochronous CAIs is late-stage open-system behavior of Re and Os in the asteroidal environment. The 187Os/188Os-Os systematics of CAIs are consistent with previous models that indicate group II CAIs are mixtures of components that lost the bulk of their highly refractory elements in a previous condensation event and a minor second component that provided refractory elements at chondritic relative proportions. The high Re/Os of group II CAIs relative to other CAIs and chondrite bulk rocks may have been caused by variable mobilization of Re and Os during medium- to low-temperature parent body alteration ??4.5 Ga ago. This model is favored over nebular models, which pose several difficulties. The narrow range of 187Os/188Os in group I, III, V, and VI bulk CAIs, and the agreement with 187Os/188Os of whole rock carbonaceous chondrites suggest that on a bulk inclusion scale, secondary alteration only modestly fractionated Re/Os in these CAIs. The average of 187Os/188Os for group I, III, V, and VI CAIs is indistinguishable from average CI chondrites, indicating a modern solar system value for 187Os/188Os of 0.12650, corresponding to a 187Re/188Os of 0.3964. Copyright ?? 2001 Elsevier Science Ltd.

Insights into controls on hexavalent chromium in groundwater provided by environmental tracers, Sacramento Valley, California, USA

USGS Publications Warehouse

Manning, Andrew H.; Mills, Christopher T.; Morrison, Jean M.; Ball, Lyndsay B.

2015-01-01

Environmental tracers are useful for determining groundwater age and recharge source, yet their application in studies of geogenic Cr(VI) in groundwater has been limited. Environmental tracer data from 166 wells located in the Sacramento Valley, northern California, were interpreted and compared to Cr concentrations to determine the origin and age of groundwater with elevated Cr(VI), and better understand where Cr(VI) becomes mobilized and how it evolves along flowpaths. In addition to major ion and trace element concentrations, the dataset includes δ18O, δ2H, 3H concentration, 14C activity (of dissolved inorganic C), δ13C, 3He/4He ratio, and noble gas concentrations (He, Ne, Ar, Kr, Xe). Noble gas recharge temperatures (NGTs) were computed, and age-related tracers were interpreted in combination to constrain the age distribution in samples and sort them into six different age categories spanning from <60 yr old to >10,000 yr old. Nearly all measured Cr is in the form of Cr(IV). Concentrations range from <1 to 46 μg L−1, with 10% exceeding the state of California’s Cr(VI) maximum contaminant level of 10 μg L−1. Two groups with elevated Cr(VI) (⩾5 μg L−1) were identified. Group 1 samples are from the southern part of the valley and contain modern (<60 yr old) water, have elevated NO3− concentrations (>3 mg L−1), and commonly have δ18O values enriched relative to local precipitation. These samples likely contain irrigation water and are elevated due to accelerated mobilization of Cr(VI) in the unsaturated zone (UZ) in irrigated areas. Group 2 samples are from throughout the valley and typically contain water 1000–10,000 yr old, have δ18O values consistent with local precipitation, and have unexpectedly warm NGTs. Chromium(VI) concentrations in Group 2 samples may be elevated for multiple reasons, but the hypothesis most consistent with all available data (notably, the warm NGTs) is a relatively long UZ residence time due to recharge through a deep UZ near the margin of the basin. A possible explanation for why Cr(VI) may be primarily mobilized in the UZ rather than farther along flowpaths in the oxic portion of the saturated zone is more dynamic cycling of Mn in the UZ due to transient moisture and redox conditions.

X-Ray Diffraction Studies on Metal Deposition in Group D Streptococci

PubMed Central

Tucker, Fayne L.; Thomas, John W.; Appleman, Milo D.; Goodman, Stewart H.; Donohue, Jerry

1966-01-01

Tucker, Fayne L. (University of Southern California, Los Angeles), John W. Thomas, Milo D. Appleman, Stewart H. Goodman, and Jerry Donohue. X-ray diffraction studies on metal deposition in group D streptococci. J. Bacteriol. 92:1311–1314. 1966.—Streptococcus faecalis N83 and S. faecium K6A reduced several compounds of Group VI elements to the elemental form, but reduced none of several compounds tested containing elements of other groups. The elemental tellurium deposited by S. faecium K6A was in general of a larger particle size than that deposited by S. faecalis N83 as judged from X-ray diffraction analysis. The particle size of the deposited tellurium was correlated with the blackness of the precipitate produced by cells growing in the presence of tellurite. A black and gray variation was observed in S. faecium K6A which was considered to be due to particle size, the amount of tellurium present, and the location of the deposited tellurium. The gray color of S. faecium K6A was not due to the presence of any oxidized tellurium products. PMID:4958879

Efficacy and immunogenicity of a Vi-tetanus toxoid conjugate vaccine in the prevention of typhoid fever using a controlled human infection model of Salmonella Typhi: a randomised controlled, phase 2b trial.

PubMed

Jin, Celina; Gibani, Malick M; Moore, Maria; Juel, Helene B; Jones, Elizabeth; Meiring, James; Harris, Victoria; Gardner, Jonathan; Nebykova, Anna; Kerridge, Simon A; Hill, Jennifer; Thomaides-Brears, Helena; Blohmke, Christoph J; Yu, Ly-Mee; Angus, Brian; Pollard, Andrew J

2017-12-02

Salmonella enterica serovar Typhi (S Typhi) is responsible for an estimated 20 million infections and 200 000 deaths each year in resource poor regions of the world. Capsular Vi-polysaccharide-protein conjugate vaccines (Vi-conjugate vaccines) are immunogenic and can be used from infancy but there are no efficacy data for the leading candidate vaccine being considered for widespread use. To address this knowledge gap, we assessed the efficacy of a Vi-tetanus toxoid conjugate vaccine using an established human infection model of S Typhi. In this single-centre, randomised controlled, phase 2b study, using an established outpatient-based human typhoid infection model, we recruited healthy adult volunteers aged between 18 and 60 years, with no previous history of typhoid vaccination, infection, or prolonged residency in a typhoid-endemic region. Participants were randomly assigned (1:1:1) to receive a single dose of Vi-conjugate (Vi-TT), Vi-polysaccharide (Vi-PS), or control meningococcal vaccine with a computer-generated randomisation schedule (block size 6). Investigators and participants were masked to treatment allocation, and an unmasked team of nurses administered the vaccines. Following oral ingestion of S Typhi, participants were assessed with daily blood culture over a 2-week period and diagnosed with typhoid infection when meeting pre-defined criteria. The primary endpoint was the proportion of participants diagnosed with typhoid infection (ie, attack rate), defined as persistent fever of 38°C or higher for 12 h or longer or S Typhi bacteraemia, following oral challenge administered 1 month after Vi-vaccination (Vi-TT or Vi-PS) compared with control vaccination. Analysis was per protocol. This trial is registered with ClinicalTrials.gov, number NCT02324751, and is ongoing. Between Aug 18, 2015, and Nov 4, 2016, 112 participants were enrolled and randomly assigned; 34 to the control group, 37 to the Vi-PS group, and 41 to the Vi-TT group. 103 participants completed challenge (31 in the control group, 35 in the Vi-PS group, and 37 in the Vi-TT group) and were included in the per-protocol population. The composite criteria for typhoid diagnosis was met in 24 (77%) of 31 participants in the control group, 13 (35%) of 37 participants in the Vi-TT group, and 13 (35%) of 35 participants in the Vi-PS group to give vaccine efficacies of 54·6% (95% CI 26·8-71·8) for Vi-TT and 52·0% (23·2-70·0) for Vi-PS. Seroconversion was 100% in Vi-TT and 88·6% in Vi-PS participants, with significantly higher geometric mean titres detected 1-month post-vaccination in Vi-TT vaccinees. Four serious adverse events were reported during the conduct of the study, none of which were related to vaccination (one in the Vi-TT group and three in the Vi-PS group). Vi-TT is a highly immunogenic vaccine that significantly reduces typhoid fever cases when assessed using a stringent controlled model of typhoid infection. Vi-TT use has the potential to reduce both the burden of typhoid fever and associated health inequality. The Bill & Melinda Gates Foundation and the European Commission FP7 grant, Advanced Immunization Technologies (ADITEC). Copyright © 2017 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.

Mechanism study of humic acid functional groups for Cr(VI) retention: Two-dimensional FTIR and 13C CP/MAS NMR correlation spectroscopic analysis.

PubMed

Zhang, Jia; Chen, Linpeng; Yin, Huilin; Jin, Song; Liu, Fei; Chen, Honghan

2017-06-01

Undissolved humic acid (HA) is known to substantially effect the migration and transformation of hexavalent chromium [Cr(VI)] in soils. The mechanisms of Cr(VI) retention in soils by undissolved HA have been reported; however, past studies are inconclusive about the types of HA functional groups that are involved in Cr(VI) retention and the retention mechanisms. Utilizing a two-dimensional correlation spectroscopy (2DCOS) analysis for FTIR and 13 C CP/MAS NMR, this study investigated the variations of HA function groups and molecular structures after reactions with aqueous Cr(VI) under different pH conditions. Based on the changing sequence of functional groups interpreted from the 2DCOS results, a four-step mechanism for Cr(VI) retention was determined as follows: (1) electrostatic adsorption of Cr(VI) to HA surface, (2) complexation of adsorbed Cr(VI) by carboxyl and ester, (3) reduction of complexed Cr(VI) to Cr(III) by phenol and polysaccharide, and (4) complexation of reduced Cr(III) by carboxylic groups. These functional groups that are involved in Cr(VI) retention were determined to occur in aromatic domains. Copyright © 2017 Elsevier Ltd. All rights reserved.

Method of manufacturing semiconductor having group II-group VI compounds doped with nitrogen

DOEpatents

Compaan, Alvin D.; Price, Kent J.; Ma, Xianda; Makhratchev, Konstantin

2005-02-08

A method of making a semiconductor comprises depositing a group II-group VI compound onto a substrate in the presence of nitrogen using sputtering to produce a nitrogen-doped semiconductor. This method can be used for making a photovoltaic cell using sputtering to apply a back contact layer of group II-group VI compound to a substrate in the presence of nitrogen, the back coating layer being doped with nitrogen. A semiconductor comprising a group II-group VI compound doped with nitrogen, and a photovoltaic cell comprising a substrate on which is deposited a layer of a group II-group VI compound doped with nitrogen, are also included.

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

PubMed

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.

Safety and immunogenicity of a Vi-DT typhoid conjugate vaccine: Phase I trial in Healthy Filipino adults and children.

PubMed

Capeding, Maria Rosario; Teshome, Samuel; Saluja, Tarun; Syed, Khalid Ali; Kim, Deok Ryun; Park, Ju Yeon; Yang, Jae Seung; Kim, Yang Hee; Park, Jiwook; Jo, Sue-Kyoung; Chon, Yun; Kothari, Sudeep; Yang, Seon-Young; Ham, Dong Soo; Ryu, Ji Hwa; Hwang, Hee-Seong; Mun, Ju-Hwan; Lynch, Julia A; Kim, Jerome H; Kim, Hun; Excler, Jean-Louis; Sahastrabuddhe, Sushant

2018-06-18

Typhoid fever remains a major public health problem in low- and middle-income countries where children aged 2-14 years bear the greatest burden. Vi polysaccharide is poorly immunogenic in children <2 years of age, and protection in adults is modest. The limitations of Vi polysaccharide vaccines can be overcome by conjugation of the Vi to a carrier protein. A typhoid conjugate vaccine composed of Vi polysaccharide conjugated to diphtheria toxoid (Vi-DT) has been developed. The Phase I study results are presented here. This was a randomized, observer-blinded Phase I study to assess the safety and immunogenicity of Vi-DT compared to Vi polysaccharide vaccine, conducted in Manila, Philippines. Participants enrolled in an age de-escalation manner (18-45, 6-17 and 2-5 years) were randomized between Test (Vi-DT, 25 µg) administered at 0 and 4 weeks and Comparator (Vi polysaccharide, Typhim Vi® and Vaxigrip®, Sanofi Pasteur) vaccines. A total of 144 participants were enrolled (48 by age strata, 24 in Test and Comparator groups each). No serious adverse event was reported in either group. Solicited and unsolicited adverse events were mild or moderate in both groups with the exception of a 4-year old girl in Test group with grade 3 fever which resolved without sequelae. All participants in Test group seroconverted after first and second doses of Vi-DT while the proportions in the Comparator group were 97.1% and 97.2%, after first dose of Typhim Vi® and second dose of Vaxigrip®, respectively. Vi-DT showed 4-fold higher Geometric Mean Titers (GMT) compared to Typhim Vi® (adjusted for age strata, p < 0.001). No further increase of GMT was detected after the second dose of Vi-DT. Anti-DT IgG seroresponse rates were 81.2% and 84.5% post first and second Vi-DT doses, respectively. Vi-DT vaccine was safe, well-tolerated and immunogenic in participants aged 2-45 years. ClinicalTrials.gov registration number: NCT02645032. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Relation between various chromium compounds and some other elements in fumes from manual metal arc stainless steel welding.

PubMed

Matczak, W; Chmielnicka, J

1993-03-01

For the years 1987-1990 160 individual samples of manual metal arc stainless steel (MMA/SS) welding fumes from the breathing zone of welders in four industrial plants were collected. Concentrations of soluble and insoluble chromium (Cr) III and Cr VI compounds as well as of some other welding fume elements (Fe, Mn, Ni, F) were determined. Concentration of welding fumes in the breathing zone ranged from 0.2 to 23.4 mg/m3. Total Cr amounted to 0.005-0.991 mg/m3 (including 0.005-0.842 mg/m3 Cr VI). Total Cr content of fumes varied from 0.1 to 7.4%. The distribution of particular Cr compounds was: 52.6% soluble Cr (including 50.7% Cr VI), 65.5% total Cr VI, and 11.4% insoluble Cr VI. The results obtained indicate that MMA/SS welding is a process that could be highly hazardous to human health. Evaluation of occupational exposure has shown that MMA/SS welders may exceed the admissible concentrations of soluble and insoluble Cr VI forms as well as of Mn and Ni. In the plants investigated the sum of the ratios of concentrations of particular welding fumes in the breathing zone of welders exceeded corresponding maximum allowable concentration values by 24 times (including 17 times for total Cr VI). Due to the variety and changeability of particular parameters occurring in the working environment, the composition of MMA/SS welding fumes (in the welder's breathing zone) is so variable that it is not possible to assess the exposure by means of one universal exposure indicator (maximum additive hygienic limit value). The evaluation should be based on the results of measurements of concentrations of particular elements in welding fumes.

Relation between various chromium compounds and some other elements in fumes from manual metal arc stainless steel welding.

PubMed Central

Matczak, W; Chmielnicka, J

1993-01-01

For the years 1987-1990 160 individual samples of manual metal arc stainless steel (MMA/SS) welding fumes from the breathing zone of welders in four industrial plants were collected. Concentrations of soluble and insoluble chromium (Cr) III and Cr VI compounds as well as of some other welding fume elements (Fe, Mn, Ni, F) were determined. Concentration of welding fumes in the breathing zone ranged from 0.2 to 23.4 mg/m3. Total Cr amounted to 0.005-0.991 mg/m3 (including 0.005-0.842 mg/m3 Cr VI). Total Cr content of fumes varied from 0.1 to 7.4%. The distribution of particular Cr compounds was: 52.6% soluble Cr (including 50.7% Cr VI), 65.5% total Cr VI, and 11.4% insoluble Cr VI. The results obtained indicate that MMA/SS welding is a process that could be highly hazardous to human health. Evaluation of occupational exposure has shown that MMA/SS welders may exceed the admissible concentrations of soluble and insoluble Cr VI forms as well as of Mn and Ni. In the plants investigated the sum of the ratios of concentrations of particular welding fumes in the breathing zone of welders exceeded corresponding maximum allowable concentration values by 24 times (including 17 times for total Cr VI). Due to the variety and changeability of particular parameters occurring in the working environment, the composition of MMA/SS welding fumes (in the welder's breathing zone) is so variable that it is not possible to assess the exposure by means of one universal exposure indicator (maximum additive hygienic limit value). The evaluation should be based on the results of measurements of concentrations of particular elements in welding fumes. PMID:8457491

Method for making graded I-III-VI.sub.2 semiconductors and solar cell obtained thereby

DOEpatents

Devaney, Walter E.

1987-08-04

Improved cell photovoltaic conversion efficiencies are obtained by the simultaneous elemental reactive evaporation process of Mickelsen and Chen for making semiconductors by closer control of the evaporation rates and substrate temperature during formation of the near contact, bulk, and near junction regions of a graded I-III-VI.sub.2, thin film, semiconductor, such as CuInSe.sub.2 /(Zn,Cd)S or another I-III-VI.sub.2 /II-VI heterojunction.

Group I-III-VI.sub.2 semiconductor films for solar cell application

DOEpatents

Basol, Bulent M.; Kapur, Vijay K.

1991-01-01

This invention relates to an improved thin film solar cell with excellent electrical and mechanical integrity. The device comprises a substrate, a Group I-III-VI.sub.2 semiconductor absorber layer and a transparent window layer. The mechanical bond between the substrate and the Group I-III-VI.sub.2 semiconductor layer is enhanced by an intermediate layer between the substrate and the Group I-III-VI.sub.2 semiconductor film being grown. The intermediate layer contains tellurium or substitutes therefor, such as Se, Sn, or Pb. The intermediate layer improves the morphology and electrical characteristics of the Group I-III-VI.sub.2 semiconductor layer.

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

PubMed

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.

Reactively-sputtered zinc semiconductor films of high conductivity for heterojunction devices

NASA Technical Reports Server (NTRS)

Stirn, Richard J. (Inventor)

1986-01-01

A high conductivity, n-doped semiconductor film is produced from zinc, or Zn and Cd, and group VI elements selected from Se, S and Te in a reactive magnetron sputtering system having a chamber with one or two targets, a substrate holder, means for heating the substrate holder, and an electric field for ionizing gases in the chamber. Zinc or a compound of Zn and Cd is placed in the position of one of the two targets and doping material in the position of the other of the two targets. Zn and Cd may be placed in separate targets while a dopant is placed in the third target. Another possibility is to place an alloy of Zn and dopant, or Zn, Cd and dopant in one target, thus using only one target. A flow of the inert gas is ionized and directed toward said targets, while a flow of a reactant gas consisting of hydrides of the group VI elements is directed toward a substrate on the holder. The targets are biased to attract negatively ionized inert gas. The desired stochiometry for high conductivity is achieved by controlling the temperature of the substrate, and partial pressures of the gases, and the target power and total pressure of the gases in the chamber.

Transition Region Abundance Measurements During Impulsive Heating Events

NASA Astrophysics Data System (ADS)

Warren, Harry P.; Brooks, David H.; Doschek, George A.; Feldman, Uri

2016-06-01

It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have shown that in the solar corona, low-FIP elements such as Fe, Si, Mg, and Ca, are generally enriched relative to high-FIP elements such as C, N, O, Ar, and Ne. In this paper we report on measurements of plasma composition made during impulsive heating events observed at transition region temperatures with the Extreme Ultraviolet Imaging Spectrometer (EIS) on Hinode. During these events the intensities of O IV, v, and VI emission lines are enhanced relative to emission lines from Mg v, VI, and vii and Si VI and vii, and indicate a composition close to that of the photosphere. Long-lived coronal fan structures, in contrast, show an enrichment of low-FIP elements. We conjecture that the plasma composition is an important signature of the coronal heating process, with impulsive heating leading to the evaporation of unfractionated material from the lower layers of the solar atmosphere and higher-frequency heating leading to long-lived structures and the accumulation of low-FIP elements in the corona.

Landolt-Börnstein: Group 6:2c, 1982. Numerical Data and Functional Relationships in Science and Technology - New Series Group 6: 2C -- "Astronomy and Astrophysics -- Interstellar Matter, Galaxy, Universe"

NASA Astrophysics Data System (ADS)

Biermann, P.; Fink, H. H.; Fricke, K. J.; Gliese, W.; Grewing, M.; Huchtmeier, W. K.; Madore, B. F.; Netzer, H.; Rahe, J.; Scheffler, H.; Schmadel, L. D.; Schmid-Burgk, J.; Tammann, G. A.; Trümper, J.; Wielen, R.; Witzel, A.; Zech, G.

The full Landolt-Börnstein Group 6 series contains: VI/1 Astronomy and Astrophysics · Astronomy and Astrophysics VI/2a Astronomy and Astrophysics · Astronomy and Astrophysics · Methods, Constants, Solar System VI/2b Astronomy and Astrophysics · Astronomy and Astrophysics · Stars and Star Clusters VI/2c Astronomy and Astrophysics · Astronomy and Astrophysics · Interstellar Matter, Galaxy, Universe VI/3a Astronomy and Astrophysics · Astronomy and Astrophysics · Instruments, Methods, Solar System VI/3b Astronomy and Astrophysics · Astronomy and Astrophysics · Stars and Star Clusters VI/3c Astronomy and Astrophysics · Astronomy and Astrophysics · Interstellar Matter, Galaxy, Universe VI/4B Astronomy and Astrophysics · The Solar System

An Exploratory Study on the Pathways of Cr (VI) Reduction in Sulfate-reducing Up-flow Anaerobic Sludge Bed (UASB) Reactor

PubMed Central

Qian, Jin; Wei, Li; Liu, Rulong; Jiang, Feng; Hao, Xiaodi; Chen, Guang-Hao

2016-01-01

Electroplating wastewater contains both Cr (VI) and sulfate. So Cr (VI) removal under sulfate-rich condition is quite complicated. This study mainly investigates the pathways for Cr (VI) removal under biological sulfate-reducing condition in the up-flow anaerobic sludge bed (UASB) reactor. Two potential pathways are found for the removal of Cr (VI). The first one is the sulfidogenesis-induced Cr (VI) reduction pathway (for 90% Cr (VI) removal), in which Cr (VI) is reduced by sulfide generated from biological reduction of sulfate. The second one leads to direct reduction of Cr (VI) which is utilized by bacteria as the electron acceptor (for 10% Cr (VI) removal). Batch test results confirmed that sulfide was oxidized to elemental sulfur instead of sulfate during Cr (VI) reduction. The produced extracellular polymeric substances (EPS) provided protection to the microbes, resulting in effective removal of Cr (VI). Sulfate-reducing bacteria (SRB) genera accounted for 11.1% of the total bacterial community; thus they could be the major organisms mediating the sulfidogenesis-induced reduction of Cr (VI). In addition, chromate-utilizing genera (e.g. Microbacterium) were also detected, which were possibly responsible for the direct reduction of Cr (VI) using organics as the electron donor and Cr (VI) as the electron acceptor. PMID:27021522

[Affinity of the elements in group VI of the periodic table to tumors and organs].

PubMed

Ando, A; Hisada, K; Ando, I

1976-10-01

In order to investigate the tumor affinity radioisotopes, chromium (51Cr), molybdenum (99Mo), tungsten (181W), selenium (75Se) and tellurium (127mTe)--the elements of group VI in the periodic table--were examined, using the rats which were subcutaneously transplanted with Yoshida sarcoma. Seven preprarations, sodium chromate (Na251CrO4), chromium chloride (51CrCl3), normal ammonium molybdate ((NH4)299MoO7), sodium tungstate (Na2181WO4), sodium selenate (Na275SeO4), sodium selenite (Na275SeO3) and tellurous acid (H2127mTeO3) were injected intravenously to each group of tumor bearing rats. These rats were sacrificed at various periods after injection of each preparation: 3 hours, 24 hours and 48 hours in all preparations. The radioactivities of the tumor, blood, muscle, liver, kidney and spleen were measured by a well-type scintillation counter, and retention values (in every tissue including the tumor) were calculated in percent of administered dose per g-tissue weight. All of seven preparations did not have any affinity for malignant tumor. Na251CrO4 and H2127mTeO3 had some affinity for the kidneys, and Na275SeO3 had some affinity for the liver. Na2181WO4 and (NH4)299MoO4 disappeared very rapidly from the blood and soft tissue, and about seventy-five percent of radioactivity was excreted in urine within first 3 hours.

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

DOE PAGES

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

2016-09-07

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

[Antagonistic effect of N-acetylcysteine on apoptosis of L-02 hepatocyte induced by Cr(VI) with or without caspase inhibitor].

PubMed

Chen, Jing; Zhong, Caigao; Zeng, Ming; Liu, Xinmin; Deng, Yuanyuan; Xiao, Fang

2010-11-01

To explore the antagonistic effect of N-acetylcysteine (NAC) on hexevalent chromium (Cr(VI))-induced apoptosis in L-02 hepatocytes with or without caspase inhibitors. L-02 hepatocytes were randomly divided into a control group, and Cr( VI), Z-VAD-fmk + Cr(VI), NAC + Cr(VI), Z-VAD-fmk + NAC + Cr (VI) four treatment groups, in which L-02 hepatocytes were cultured with Cr (VI) at the dose of 20 micromol/L for 6h. The rates of apoptosis in all groups were detected by flow cytometry (FC) after staining with propidium iodide (PI). The changes of mitochondrial membrane potential (deltapsim) and permeability transition pore (PTP) were determined by fluorescent spectrometer. The DNA damages in hepatocytes were observed by the single cell gel electrophoresis (SCGE). Cr(VI) significantly induced apoptosis of L-02 hepatocytes at the dose of 20 micromol/L for 6 hours (P < 0.05). However, NAC significantly decreased the rates of apoptosis of L-02 hepatocytes and alleviated the damages to mitochondria and DNA caused by Cr(VI) in L-02 hepatocytes with or without caspase (P < 0.05). However, in comparition with the non caspase-inhibited group, the protective effects of NAC decreased in the caspase-inhibited group (P < 0.05). NAC could protect the apoptosis of L-02 hepatocyte induced with Cr(VI) with or without caspase inhibitor, and caspase could not play a decisive role in this process.

Adaptable Structural Logic System Synthesis with Bistable Snap-Through Elements

DTIC Science & Technology

2012-12-01

It is well known that an unsymmetrical laminates exhibit out-of-plane displacements at room temperature even if cured flat . The unsymmetrical...various input frequencies and the loss factor of the system is evaluated. Figure VI-7: Three-cell test bed 59 \\ imm) W TELEDYNE SCIENTIFIC...design. 4- 4 Figure VI-9: Panoramic view of 10 cell test bed 60 w TELEDYNE SCIENTIFIC & IMAGING, LLC ATeledyne Technologies Company Table VI-2

Microbial oxidation of elemental selenium in soil slurries and bacterial cultures

USGS Publications Warehouse

Dowdle, P.R.; Oremland, R.S.

1998-01-01

The microbial oxidation of elemental selenium [Se(O)] was studied by employing 75Se(O) as a tracer. Live, oxic soil slurries demonstrated a linear production of mostly Se(IV), with the formation of smaller quantities of Se(VI). Production of both Se(IV) and Se(VI) was inhibited by autoclaving, formalin, antibiotics, azide, and 2,4-dinitrophenol, thereby indicating the involvement of microbes. Oxidation of Se(O) in slurries was enhanced by addition of acetate, glucose, or sulfide, which implied involvement of chemoheterotrophs as well as chemoautotrophic thiobacilli. Cultures of Thiobacillus ASN-1, Leptothrix MnB1, and a heterotrophic soil enrichment all oxidized Se(O) with Se(VI) observed as the major product rather than Se(IV). This indicated that microbial oxidation in soils is partly constrained by the adsorption of Se(IV) onto soil surfaces. Rate constants for unamended soil slurry Se(O) oxidation ranged from 0.0009 to 0.0117 day-1 which were 3-4 orders of magnitude lower than those reported for dissimilatory Se(VI) reduction in organic-rich, anoxic sediments.The microbial oxidation of elemental selenium [Se(0)] was studied by employing 75Se(0) as a tracer. Live, oxic soil slurries demonstrated a linear production of mostly Se(IV), with the formation of smaller quantities of Se(VI). Production of both Se(IV) and Se(VI) was inhibited by autoclaving, formalin, antibiotics, azide, and 2,4-dinitrophenol, thereby indicating the involvement of microbes. Oxidation of Se(O) in slurries was enhanced by addition of acetate, glucose, or sulfide, which implied involvement of chemoheterotrophs as well as chemoautotrophic thiobacilli. Cultures of Thiobacillus ASN-1, Leptothrix MnB1, and a heterotrophic soil enrichment all oxidized Se(O) with Se(VI) observed as the major product rather than Se(IV). This indicated that microbial oxidation in soils is partly constrained by the adsorption of Se(IV) onto soil surfaces. Rate constants for unamended soil slurry Se(O) oxidation ranged from 0.0009 to 0.0117 day-1 which were 3-4 orders of magnitude lower than those reported for dissimilatory Se(VI) reduction in organic-rich, anoxic sediments.

Multi-crystalline II-VI based multijunction solar cells and modules

DOEpatents

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.

Electrochemical photovoltaic cell having ternary alloy film

DOEpatents

Russak, Michael A.

1984-01-01

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

Materials Characterization and Microelectronic Implementation of Metal-insulator Transition Materials and Phase Change Materials

DTIC Science & Technology

2015-03-26

appropriate. Group 16 (VI) contains the following elements: Oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po). They are shown...below in Figure 33. S, Se, and Te are referred to as chalcogens, and their compounds are chalcogenides [68]. Polonium is excluded from the chalcogen...temperature dots and paint were placed on samples on the substrate. Temperature dots are typically used in the transportation of goods such as food in order

Redox chemistry of molybdenum in natural waters and its involvement in biological evolution

PubMed Central

Wang, Deli

2012-01-01

The transition element molybdenum (Mo) possesses diverse valances (+II to +VI), and is involved in forming cofactors in more than 60 enzymes in biology. Redox switching of the element in these enzymes catalyzes a series of metabolic reactions in both prokaryotes and eukaryotes, and the element therefore plays a fundamental role in the global carbon, nitrogen, and sulfur cycling. In the present oxygenated waters, oxidized Mo(VI) predominates thermodynamically, whilst reduced Mo species are mainly confined within specific niches including cytoplasm. Only recently has the reduced Mo(V) been separated from Mo(VI) in sulfidic mats and even in some reducing waters. Given the presence of reduced Mo(V) in contemporary anaerobic habitats, it seems that reduced Mo species were present in the ancient reducing ocean (probably under both ferruginous and sulfidic conditions), prompting the involvement of Mo in enzymes including nitrogenase and nitrate reductase. During the global transition to oxic conditions, reduced Mo species were constrained to specific anaerobic habitats, and efficient uptake systems of oxidized Mo(VI) became a selective advantage for current prokaryotic and eukaryotic cells. Some prokaryotes are still able to directly utilize reduced Mo if any exists in ambient environments. In total, this mini-review describes the redox chemistry and biogeochemistry of Mo over the Earth’s history. PMID:23267355

Role of functional groups on Aspergillus niger biomass in the detoxification of hexavalent chromium.

PubMed

Narvekar, Sneha; Vaidya, Varsha K

2009-10-01

Chromium (VI) contamination is not uncommon, especially near industries involved in leather tanning, chrome painting, metal cleaning and processing, wood preservation and alloy preparation. The mutagenic and carcinogenic properties of Chromium (VI) necessitate effective remedial processes. Difficulties associated with chemical and physical techniques to remediate a Chromium (VI) contaminated site to EPA recommended level (50 ppm), in addition to higher costs involved, assert the need for bioremedial measures. Biosorption can be one such solution to clean up heavy metal contamination. The objective of this study was to examine the main aspects of a possible strategy for the removal of Chromium (VI), employing Aspergillus niger biomass. The roles played by amines, carboxylic acids, phosphates, in Chromium (VI) biosorption were studied. Amino and the carboxy groups on the fungal cell wall play an important role in sorption. However, the role of carboxy group was far less than amino group. Surface adsorption of Chromium (VI) was also seen by scanning electron microscopy (SEM) thus indicating involvement of ion-exchange and surface adsorption mechanism in removal of Chromium (VI) ions.

Indexes of temporal myocardial repolarization dispersion and sudden cardiac death in heart failure: any difference?

PubMed

Piccirillo, Gianfranco; Rossi, Pietro; Mitra, Marilena; Quaglione, Raffaele; Dell'Armi, Annalaura; Di Barba, Daniele; Maisto, Damiana; Lizio, Andrea; Barillà, Francesco; Magrì, Damiano

2013-03-01

The QT variability index, calculated between Q- and the T-wave end (QTend VI), is an index of temporal myocardial repolarization lability associated with sudden cardiac death (SCD) in chronic heart failure (CHF). Little is known about temporal variability in the other two temporal myocardial repolarization descriptors obtained from Q-Tpeak and Tpeak -Tend intervals. We therefore investigated differences between these indexes in patients with CHF who died suddenly and in those who survived with a left ventricular ejection fraction (LVEF) ≤35% or >35%. We selected 127 ECG and systolic blood pressure (SPB) recordings from outpatients with CHF all of whom had been followed up for 30 months. We calculated RR and SPB variability by power spectral analysis and QTend VI, QTpeak VI, Tpeak Tend VI. We then subdivided data patients into three groups SCD, LVEF ≤ 35%, and LVEF > 35%. The LVEF was higher in the SCD than in the LVEF ≤ 35% group, whereas no difference was found between the SCD and LVEF > 35% groups. QTend VI, QTpeak VI, and Tpeak Tend VI were higher in the SCD and LVEF ≤ 35% groups than in the LVEF > 35% group. Multivariate analysis detected a negative relationship between all repolarization variability indexes, low frequency obtained from RR intervals and LVEF. Our data show that variability in the first (QTpeak VI) and second halves of the QT interval (Tpeak -Tend VI) significantly contributes to the QTend VI in patients with CHF. Further studies should investigate whether these indexes might help stratify the risk of SCD in patients with a moderately depressed LVEF. ©2012, Wiley Periodicals, Inc.

Removal of hexavalent Cr by coconut coir and derived chars--the effect of surface functionality.

PubMed

Shen, Ying-Shuian; Wang, Shan-Li; Tzou, Yu-Min; Yan, Ya-Yi; Kuan, Wen-Hui

2012-01-01

The Cr(VI) removal by coconut coir (CC) and chars obtained at various pyrolysis temperatures were evaluated. Increasing the pyrolysis temperature resulted in an increased surface area of the chars, while the corresponding content of oxygen-containing functional groups of the chars decreased. The Cr(VI) removal by CC and CC-derived chars was primarily attributed to the reduction of Cr(VI) to Cr(III) by the materials and the extent and rate of the Cr(VI) reduction were determined by the oxygen-containing functional groups in the materials. The contribution of pure Cr(VI) adsorption to the overall Cr(VI) removal became relatively significant for the chars obtained at higher temperatures. Accordingly, to develop a cost-effective method for removing Cr(VI) from water, the original CC is more advantageous than the carbonaceous counterparts because no pyrolysis is required for the application and CC has a higher content of functional groups for reducing Cr(VI) to less toxic Cr(III). Copyright © 2011 Elsevier Ltd. All rights reserved.

Degradation of chloramphenicol by potassium ferrate (VI) oxidation: kinetics and products.

PubMed

Zhou, Jia-Heng; Chen, Kai-Bo; Hong, Qian-Kun; Zeng, Fan-Cheng; Wang, Hong-Yu

2017-04-01

The oxidation of chloramphenicol (CAP) by potassium ferrate (VI) in test solution was studied in this paper. A series of jar tests were performed at bench scale with pH of 5-9 and molar ratio [VI/CAP] of 16.3:1-81.6:1. Results showed that raising VI dose could improve the treatment performance and the influence of solution pH was significant. VI is more reactive in neutral conditions, presenting the highest removal efficiency of CAP. The rate law for the oxidation of CAP by VI was first order with respect to each reactant, yielding an overall second-order reaction. Furthermore, five oxidation products were observed during CAP oxidation by VI. Results revealed that VI attacked the amide group of CAP, leading to the cleavage of the group, while benzene ring remained intact.

Synthesis, analgesic, anti-inflammatory and anti-ulcerogenic activities of certain novel Schiff's bases as fenamate isosteres.

PubMed

Alafeefy, Ahmed M; Bakht, Mohammed A; Ganaie, Majid A; Ansarie, Mohd N; El-Sayed, Nahed N; Awaad, Amani S

2015-01-15

A series of certain novel Schiff bases as fenamate isosteres (VI:a-k) were synthesized to locate analgesic, anti-inflammatory agent with minimal ulcerogenic potential. The structures of the newly synthesized compounds were elucidated on the basis of their elemental analysis as well as IR, and NMR and mass spectroscopic data. All the compounds were evaluated for their anti-inflammatory activity by carrageenan induced paw oedema method. The compounds possessing good anti-inflammatory activity were further tested for analgesic, ulcerogenic, lipid peroxidation potentials and liver toxicity. Compounds (VI-c), (VI-f), (VI-h) and (VI-i) showed the best anti-inflammatory and significant analgesic activities at doses comparable to that of the standard drug Indomethacin. However, compounds (VI-c) and (VI-f) could be considered the most potent anti-inflammatory and analgesic molecules with maximum reduction in gastro-intestinal ulceration with no hepatocyte necrosis or liver degeneration. Copyright © 2014 Elsevier Ltd. All rights reserved.

Contributions and Follow-Up Activities to CONFINTEA VI (USA)

ERIC Educational Resources Information Center

Alamprese, Judith A.

2012-01-01

CONFINTEA VI provided a unique lens through which to view adult education and literacy worldwide. Over 1,000 participants from 144 countries were convened to advance the recognition of adult learning and education as important elements of lifelong learning and crucial to the agendas for international education and development. The aim was to…

Decreased endometrial vascularity and receptivity in unexplained recurrent miscarriage patients during midluteal and early pregnancy phases.

PubMed

Tan, Shu-Yin; Hang, Fu; Purvarshi, Gowreesunkur; Li, Min-Qing; Meng, Da-Hua; Huang, Ling-Ling

2015-10-01

To evaluate the predictive value of three-dimensional (3D)-power Doppler sonography on recurrent miscarriage. The study patients were divided into a recurrent miscarriage group (30 cases) and a normal pregnancy group (21 cases). Measurement of endometrial thickness was performed using two-dimensional transvaginal ultrasound in the midluteal phase. The endometrial volume, vascularization index (VI), flow index (FI), and vascularization-flow index (VFI) in midluteal and placenta volume, as well as the VI, FI, and VFI of early pregnancy were measured using Virtual Organ Computer-aided Analysis of 3D-power Doppler ultrasound. Endometrial thickness, endometrial volume, endometrial vascular data, VI, FI, and VFI of the midluteal phase were lower in the recurrent miscarriage group compared with the normal pregnancy group (p < 0.05). Placental volume, VI, and VFI during early pregnancy were lower in the miscarriage group compared with the normal pregnancy group (p < 0.05). There was no significant change in FI between the recurrent miscarriage and control groups during early pregnancy (p > 0.05). The predictive accuracy of endometrial thickness, endometrial volume, VI, FI, and VFI in the midluteal phase, and placenta volume, VI, FI, and VFI in early pregnancy as measured by the receiver operating characteristic curve to predict miscarriage before 12 gestational weeks in participants was 0.681, 0.876, 0.770, 0.720, 0.879, 0.771, 0.907, 0.592, respectively. The 3D-power Doppler ultrasound is a more comprehensive and sensitive method for evaluating endometrial receptivity. Endometrial volume, VI, FI, and VFI in the midluteal phase, as well as VI in early pregnancy, can be considered as predictive factors for recurrent miscarriage. Copyright © 2015. Published by Elsevier B.V.

Controlling Hexavalent Americium – A Centerpiece to a Compact Nuclear Fuel Cycle

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

Shafer /Braley, Jenifer; Nash, Kenneth L; Lumetta, Gregg

2014-10-01

Closing the nuclear fuel cycle could be simplified by recovering the actinides U through Am as a group. This could be achieved by converting U, Np, Pu and Am to the hexavalent state. Uranium, Np and Pu are readily oxidized to the hexavalent state. Generation of hexavalent Am in acidic solutions is more difficult, as the standard reduction potential of the Am(VI) /Am(III) couple (+1.68 V in 1 M HClO4) is well outside of the electrochemical stability window of water. While the oxidation and separation of Am has been demonstrated under laboratory conditions, several issues could plague scale up andmore » implementation of this separation with used fuel. Two primary concerns are considered. The first issue concerns the stability of the oxidized Am. The second involves the undesirable co-extraction of tetravalent f-elements with the hexavalent actinides. To address the first concern regarding Am redox instability, Am reduction will be monitored under a variety of different conditions to establish the means of improving the stability of Am(VI) in the organic phase. Identifying the components contributing most significantly to its reduction will allow thoughtful modification of the process. To address the second concern, we propose to apply branched chain extractants to separate hexavalent actinides from tetravalent f-elements. Both branched monoamide and organophosphorus extractants have demonstrated significant selectivity for UO22+ versus Th4+, with separation factors generally on the order of 100. The efforts of this two-pronged research program should represent a significant step forward in the development of aqueous separations approaches designed to recover the U-Am actinides based on the availability of the hexavalent oxidation state. For the purposes of this proposal, separations based on this approach will be called SAn(VI) separations, indicating the Separation of An(VI).« less

Stabilization of nanoscale zero-valent iron (nZVI) with modified biochar for Cr(VI) removal from aqueous solution.

PubMed

Dong, Haoran; Deng, Junmin; Xie, Yankai; Zhang, Cong; Jiang, Zhao; Cheng, Yujun; Hou, Kunjie; Zeng, Guangming

2017-06-15

Three types of modified biochar (BC) were produced respectively with acid (HCl) treatment (HCl-BC), base (KOH) treatment (KOH-BC) and oxidation (H 2 O 2 ) treatment (H 2 O 2 -BC) of raw biochar. Both the raw biochar and modified biochars supported zero valent iron nanopartilces (nZVI) (i.e. nZVI@BC, nZVI@HCl-BC, nZVI@KOH-BC and nZVI@H 2 O 2 -BC) were synthesized and their capacities for Cr(VI) removal were compared. The results showed that the nZVI@HCl-BC exhibited the best performance and the underlying mechanisms were discussed. The surface elemental distribution maps of the nZVI@HCl-BC after reaction with Cr(VI) showed that Fe, Cr and O elements were deposited on the surface of HCl-BC evenly, indicating that the formed Cr(III)/Fe(III) could settle on the surface of HCl-BC uniformly rather than coated only on the nZVI surface. This reveals that the supporter HCl-BC could also play a role in alleviating the passivation of nZVI. Besides, the effects of mass ratio (nZVI/HCl-BC), pH, and initial Cr(VI) concentration on Cr(VI) removal were examined. At lower mass of HCl-BC, nZVI aggregation cannot be fully inhibited on the surface of HCl-BC, whereas excessive biochar can block the active sites of nZVI. Additionally, it was found that Cr(VI) removal by nZVI@HCl-BC was dependent on both pH and initial Cr(VI) concentration. Copyright © 2017 Elsevier B.V. All rights reserved.

Supported metal alloy catalysts

DOEpatents

Barrera, Joseph; Smith, David C.

2000-01-01

A process of preparing a Group IV, V, or VI metal carbonitride including reacting a Group IV, V, or VI metal amide complex with ammonia to obtain an intermediate product; and, heating the intermediate product to temperatures and for times sufficient to form a Group IV, V, or VI metal carbonitride is provided together with the product of the process and a process of reforming an n-alkane by use of the product.

HNO3 modified biochars for uranium (VI) removal from aqueous solution.

PubMed

Jin, Jie; Li, Shiwei; Peng, Xianqiang; Liu, Wei; Zhang, Chenlu; Yang, Yan; Han, Lanfang; Du, Ziwen; Sun, Ke; Wang, Xiangke

2018-05-01

The HNO 3 treatment was used to chemically modify the biochars produced from wheat straw (WH) and cow manure for U(VI) removal from aqueous solution. Macroscopic experiments proved that the enrichment of U(VI) on the biochars was regulated by surface complexation and electrostatic interactions. FTIR and XPS analyses confirmed that the highly efficient adsorption of U(VI) was due to the carboxyl groups on the biochar surfaces. The reducing agents of the R-CH 2 OH groups facilitated U(VI) adsorption on the untreated biochars. Owing to the higher contents of surface COO groups and more negative surface charge, the modified biochars showed enhanced U(VI) adsorption ability than the untreated ones. The maximum adsorption capacity of U(VI) by the oxidized WH was calculated to be 355.6 mg/g at pH 4.5 and 298 K, which was an improvement of 40 times relative to the untreated WH and was higher than that of most carbon-based adsorbents. Copyright © 2018 Elsevier Ltd. All rights reserved.

Papaya Seeds as A Low-Cost Sorbent for Removing Cr(VI) from The Aqueous Solution

NASA Astrophysics Data System (ADS)

Rahmawati, Atik; Marwoto, Putut; Karunia Z, Anita

2016-08-01

The presence of chromium (VI) contaminants and their toxicity in aqueous streams important environmental problems. Adsorption is one of the effective techniques that can be used for removing metal from wastewater. This research was initiated by preparing sorbent from papaya seeds and determining its functional group contents by using FT-IR. The adsorption process was carried out in a batch method. The study of adsorption aspects involved the pH, initial Cr (VI) concentration and contact time between Cr (VI) and sorbent. FT IR analysis results showed that the main functional groups are carbonyl, hydroxyl, and carboxylic. It was also found that the effective pH for Cr (VI) uptake is 2.0 and increasing contact time would increase the Cr (VI) uptake. In addition, the equilibrium was reached after 40 minutes interaction and the increase of initial chromium (VI) concentration would increase the sorbent uptake percentage. All these results indicated that papaya seed is a potential sorbent for removing Cr (VI) from aqueous solutions.

Removal of chromium (VI) from electroplating wastewater using an anion exchanger derived from rice straw.

PubMed

Cao, Wei; Dang, Zhi; Yia, Xiao-Yun; Yang, Chen; Lu, Gui-Ning; Liu, Yun-Feng; Huang, Se-Yan; Zheng, Liu-Chun

2013-01-01

An anion exchanger from rice straw was used to remove Cr (VI) from synthetic wastewater and electroplating effluent. The exchanger was characterized using Fourier transform infrared (FTIR) spectrum and scanning electron microscopy (SEM), and it was found that the quaternary amino group and hydroxyl group are the main functional groups on the fibrous surface of the exchanger. The effect of contact time, initial concentration and pH on the removal of Cr (VI), and adsorption isotherms at different temperature, was investigated. The results showed that the removal of Cr (VI) was very rapid and was significantly affected by the initial pH of the solution. Although acidic conditions (pH = 2-6) facilitated Cr (VI) adsorption, the exchanger was effective in neutral solution and even under weak base conditions. The equilibrium data fitted well with Langmuir adsorption model, and the maximum Cr (VI) adsorption capacities at pH 6.4 were 0.35, 0.36 and 0.38 mmol/g for 15, 25 and 35 degrees C, respectively. The exchanger was finally tested with real electroplating wastewater, and at sorbent dosage of 10 g/L, the removal efficiencies for Cr (VI) and total Cr were 99.4% and 97.8%, respectively. In addition, the positive relationship between adsorbed Cr (VI) and desorbed Cl- suggested that Cr (VI) was mainly removed by ion exchange with chlorine.

Prevalence and the risk factors for visual impairment in age-related macular degeneration.

PubMed

Srinivasan, S; Swaminathan, G; Kulothungan, V; Raman, R; Sharma, T

2017-06-01

PurposeTo characterize the type, and the causes of visual impairment (VI) in various stages of early and late age-related macular degeneration (AMD) and the factors associated with visual impairment in subjects with AMDMethods6617 subjects ≥60 years were enumerated; 5495 (83.04%) participated in eye examination. Of which, 4791 subjects had gradable fundus images. AMD was graded per International ARM Epidemiological Study Group. Subjects underwent detailed ophthalmic exam. VI was defined per the WHO classification. Mild VI was defined as VA less than 6/12 to 6/18, moderate VI-VA less than 6/18 but up to 6/60, severe VI-VA less than 6/60 but up to 3/60 and legal blindness-VA worse than 3/60. Factors associated with VI in AMD was analyzed with univariate and logistic regression analysis.ResultsNine hundred and eighty-eight subjects were identified as having AMD (893 with early AMD and 95 with late AMD); 85% of the subjects (95% CI: 82.7-87.1) had no VI, 13.1% had mild VI (95% CI: 11.1-15.3), 0.8% had severe VI (95% CI: 0.4-1.6), 1.1% had legal blindness (95% CI: 0.6-1.9). Prevalence of any VI was 13.7% in early AMD and 27.4% in late AMD, P=0.0004; age group 65-70 years (OR=1.89, 95% CI: 1.16-3.08, P=0.011), and those ≥75 years (OR=3.67, 95% CI: 1.95-6.91, P=0.0001) had greater odds of VI compared with age group 60-64 years. Male gender was a protective factor for VI (OR=0.57, CI: 0.36-0.90, P=0.016). Cataract (31.8%) and refractive error (28.4%) accounted for a majority of the VI.ConclusionsCataract and refractive error account for a significant proportion of VI in the south Indian population with AMD. Early AMD is the third leading cause of VI. Greater age and female gender are associated with VI in subjects with AMD.

Semiconductor radiation detector

DOEpatents

Bell, Zane W.; Burger, Arnold

2010-03-30

A semiconductor detector for ionizing electromagnetic radiation, neutrons, and energetic charged particles. The detecting element is comprised of a compound having the composition I-III-VI.sub.2 or II-IV-V.sub.2 where the "I" component is from column 1A or 1B of the periodic table, the "II" component is from column 2B, the "III" component is from column 3A, the "IV" component is from column 4A, the "V" component is from column 5A, and the "VI" component is from column 6A. The detecting element detects ionizing radiation by generating a signal proportional to the energy deposited in the element, and detects neutrons by virtue of the ionizing radiation emitted by one or more of the constituent materials subsequent to capture. The detector may contain more than one neutron-sensitive component.

Spectroscopic studies of U(VI) sorption at the kaolinite-water interface. Final report

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

Thompson, H.A.; Parks, G.A.; Brown, G.E. Jr.

Efficient use of U as a resource and safe handling, recycling and disposal of U-containing wastes require an understanding of the factors controlling the fate of U, where fate refers to the destination of U, typically expressed as an environmental medium or a process phase. The sorption process constitutes a change in elemental fate. Partitioning of an element from solution to a solid phase, or sorption, can be divided into three broad categories: adsorption, surface precipitation, and absorption. Extended X-ray absorption fine structure (EXAFS), a type of X-ray absorption spectroscopy (XAS), offers the possibility for distinguishing among different modes ofmore » sorption by characterizing the atomic environment of the sorbing element. In this study, the authors use EXAFS to determine the structure of U(VI) sorption complexes at the kaolinite-water interface. In Chapter One, they present an overview of selected aspects of U structural chemistry as a basis for considering the structural environment of U at the solid-water interface. To evaluate the utility of XAS for characterization of the structural environment of U(VI) at the solid-water interface, they have carried out an in-depth analysis of XAS data from U(VI)-containing solid and solution model compounds, which they describe in Chapter Two. In Chapter three, they consider sorption of U by kaolinite as a means of effecting the removal of U from surface collection pond waters on the Rocky Flats Plant site in northern Colorado.« less

Efficacy trial of Vi polysaccharide vaccine against typhoid fever in south-western China.

PubMed Central

Yang, H. H.; Wu, C. G.; Xie, G. Z.; Gu, Q. W.; Wang, B. R.; Wang, L. Y.; Wang, H. F.; Ding, Z. S.; Yang, Y.; Tan, W. S.; Wang, W. Y.; Wang, X. C.; Qin, M.; Wang, J. H.; Tang, H. A.; Jiang, X. M.; Li, Y. H.; Wang, M. L.; Zhang, S. L.; Li, G. L.

2001-01-01

OBJECTIVE: To test the efficacy of locally produced Vi vaccine over a time period of longer than one year. METHODS: A double-blinded, randomized field trial was performed in Guangxi Zhuang Autonomous Region in south-western China, using 30 micrograms doses of locally produced Vi. Enrolled subjects were 3-50 years of age, although the majority (92%) were school-aged children, who have the highest rate of typhoid fever in this setting. A total of 131,271 people were systematically allocated a single dose of 30 micrograms of Vi polysaccharide or saline placebo. The study population was followed for 19 months, with passive surveillance conducted in the Ministry of Health and the Regional Health and Anti-epidemic Centre (HAEC). Clinically suspected cases of typhoid fever were confirmed by blood culture, or by serological reaction with O-antigen (Widal tests). FINDINGS: After 19 months, there were 23 culture-confirmed cases of typhoid fever in the placebo group versus 7 cases in the Vi group (Protective efficacy (PE) = 69%; 95% CI = 28%, 87%). Most of the isolates were from school-aged children: 22 cases in the placebo group versus 6 in the Vi group (PE = 72%; 95% CI = 32%, 82%). No serious post-injection reactions were observed. The locally produced Vi polysaccharide vaccine showed levels of protective efficacy similar to those for Vi vaccine produced in industrial countries. CONCLUSION: The slightly higher dose of vaccine did not seem to alter efficacy significantly in China. PMID:11477965

Laser and Light Treatments for Hair Reduction in Fitzpatrick Skin Types IV-VI: A Comprehensive Review of the Literature.

PubMed

Fayne, Rachel A; Perper, Marina; Eber, Ariel E; Aldahan, Adam S; Nouri, Keyvan

2018-04-01

Unwanted facial and body hair presents as a common finding in many patients, such as females with hirsutism. With advances in laser and light technology, a clinically significant reduction in hair can be achieved in patients with light skin. However, in patients with darker skin, Fitzpatrick skin types (FST) IV-VI, the higher melanin content of the skin interferes with the proposed mechanism of laser-induced selective photothermolysis, which is to target the melanin in the hair follicle to cause permanent destruction of hair bulge stem cells. Many prospective and retrospective studies have been conducted with laser and light hair-removal devices, but most exclude patients with darkly pigmented skin, considering them a high-risk group for unwanted side effects, including pigmentation changes, blisters, and crust formation. We reviewed the published literature to obtain studies that focused on hair reduction for darker skin types. The existing literature for this patient population identifies longer wavelengths as a key element of the treatment protocol and indicates neodymium-doped yttrium aluminum garnet (Nd:YAG), diode, alexandrite, and ruby lasers as well as certain intense pulsed light sources for safe hair reduction with minimal side effects in patients with FST IV-VI, so long as energy settings and wavelengths are appropriate. Based on the findings in this review, safe and effective hair reduction for patients with FST IV-VI is achievable under proper treatment protocols and energy settings.

Cr(VI) Adsorption on Red Mud Modified by Lanthanum: Performance, Kinetics and Mechanisms

PubMed Central

Cui, You-Wei; Li, Jie; Du, Zhao-Fu; Peng, Yong-Zhen

2016-01-01

Water pollution caused by the highly toxic metal hexavalent chromium (Cr(VI)) creates significant human health and ecological risks. In this study, a novel adsorbent was used to treat Cr(VI)-containing wastewater; the adsorbent was prepared using red mud (RM) generated from the alumina production industry and the rare earth element lanthanum. This study explored adsorption performance, kinetics, and mechanisms. Results showed that the adsorption kinetics of the RM modified by lanthanum (La-RM), followed the pseudo-second-order model, with a rapid adsorption rate. Cr(VI) adsorption was positively associated with the absorbent dose, pH, temperature, and initial Cr(VI) concentration; coexisting anions had little impact. The maximum Cr(VI) adsorption capacity was 17.35 mg/g. Cr(VI) adsorption on La-RM was a mono-layer adsorption pattern, following the Langmuir isotherm model. Thermodynamic parameters showed the adsorption was spontaneous and endothermic. The adsorption of Cr(VI) on La-RM occurred as a result of LaOCl formation on the RM surface, which in turn further reacted with Cr(VI) in the wastewater. This study highlighted a method for converting industrial waste into a valuable material for wastewater treatment. The novel absorbent could be used as a potential adsorbent for treating Cr(VI)-contaminating wastewater, due to its cost-effectiveness and high adsorption capability. PMID:27658113

Modifications to EPA Method 3060A to Improve Extraction of Cr(VI) from Chromium Ore Processing Residue-Contaminated Soils

USGS Publications Warehouse

Mills, Christopher T.; Bern, Carleton R.; Wolf, Ruth E.; Foster, Andrea L.; Morrison, Jean M.; Benzel, William M.

2017-01-01

It has been shown that EPA Method 3060A does not adequately extract Cr(VI) from chromium ore processing residue (COPR). We modified various parameters of EPA 3060A toward understanding the transformation of COPR minerals in the alkaline extraction and improving extraction of Cr(VI) from NIST SRM 2701, a standard COPR-contaminated soil. Aluminum and Si were the major elements dissolved from NIST 2701, and their concentrations in solution were correlated with Cr(VI). The extraction fluid leached additional Al and Si from the method-prescribed borosilicate glass vessels which appeared to suppress the release of Cr(VI). Use of polytetrafluoroethylene vessels and intensive grinding of NIST 2701 increased the amount of Cr(VI) extracted. These modifications, combined with an increased extraction fluid to sample ratio of ≥900 mL g–1 and 48-h extraction time resulted in a maximum release of 1274 ± 7 mg kg–1 Cr(VI). This is greater than the NIST 2701 certified value of 551 ± 35 mg kg–1 but less than 3050 mg kg–1 Cr(VI) previously estimated by X-ray absorption near edge structure spectroscopy. Some of the increased Cr(VI) may have resulted from oxidation of Cr(III) released from brownmillerite which rapidly transformed during the extractions. Layered-double hydroxides remained stable during extractions and represent a potential residence for unextracted Cr(VI).

Finite Element Analysis of a Dynamically Loaded Flat Laminated Plate

DTIC Science & Technology

1980-07-01

and the elements are stacked in the thickness direction to represent various material layers. This analysis allows for orthotropic, elastic- plastic or...INCREMENTS 27 V. PLASTICITY 34 Orthotropic Elastic- Plastic Yielding 34 Orthotropic Elastic-Viscoplastic Yielding 37 VI. ELEMENT EQUILIBRIUM...with time, consequently the materials are assumed to be represented by elastic- plastic and elastic-viscoplastic models. The finite element model

Spectroscopic characterization of iron-doped II-VI compounds for laser applications

NASA Astrophysics Data System (ADS)

Martinez, Alan

The middle Infrared (mid-IR) region of the electromagnetic spectrum between 2 and 15 ?m has many features which are of interest to a variety of fields such as molecular spectroscopy, biomedical applications, industrial process control, oil prospecting, free-space communication and defense-related applications. Because of this, there is a demand for broadly tunable, laser sources operating over this spectral region which can be easily and inexpensively produced. II-VI semiconductor materials doped with transition metals (TM) such as Co 2+, Cr2+, or Fe2+ exhibit highly favorable spectroscopic characteristics for mid-IR laser applications. Among these TM dopants, Fe2+ has absorption and emission which extend the farthest into the longer wavelength portion of the mid-IR. Fe2+:II-VI crystals have been utilized as gain elements in laser systems broadly tunable over the 3-5.5 microm range [1] and as saturable absorbers to Q -switch [2] and mode-lock [3] laser cavities operating over the 2.7-3 microm. TM:II-VI laser gain elements can be fabricated inexpensively by means of post-growth thermal diffusion with large homogeneous dopant concentration and good optical quality[4,5]. The work outlined in this dissertation will focus on the spectroscopic characterization of TM-doped II-VI semiconductors. This work can be categorized into three major thrusts: 1) the development of novel laser materials, 2) improving and extending applications of TM:II-VI crystals as saturable absorbers, and 3) fabrication of laser active bulk crystals. Because current laser sources based on TM:II-VI materials do not cover the entire mid-IR spectral region, it is necessary to explore novel laser sources to extend available emissions toward longer wavelengths. The first objective of this dissertation is the spectroscopic characterization of novel ternary host crystals doped with Fe2+ ions. Using crystal field engineering, laser materials can be prepared with emissions placed in spectral regions not currently covered by available sources while maintaining absorption which overlaps with available pump sources. Because optimization of these materials requires extensive experimentation, a technique to fabricate and characterize novel crystals in powder form was developed, eliminating the need for the crystal growth. Powders were characterized using Raman, photoluminescence studies, and kinetics of luminescence. The first demonstration of random lasing of Fe:ZnCdTe powder at 6 microm was reported. These results show promise for the development of these TM-doped ternary II-VI compounds as laser gain media operating at 6 microm and longer. The second major objective was to study the performance of TM:II-VI elements as saturable absorber Q-switches and mode-lockers in flash lamp pumped Er:YAG and Er:Cr:YSGG cavities. Different cavity schemes were arranged to eliminate depolarization losses and improve Q-switching performance in Er:YAG and the first use of Cr:ZnSe to passively Q -switch an Er:Cr:YSGG cavity was demonstrated. While post-growth thermal diffusion is an effective way to prepare large-scale highly doped TM:II-VI laser elements, the diffusion rate of some ions into II-VI semiconductors is too low to make this method practical for large crystals. The third objective was to improve the rate of thermal diffusion of iron into II-VI semiconductor crystals by means of gamma-irradiation during the diffusion process. When exposed to a dose rate of 44 R/s during the diffusion process, the diffusion coefficient for Fe into ZnSe showed improvement of 60% and the diffusion coefficient of Fe into ZnS showed improvement of 30%.

Heterocycles Based on Group III, IV, and V Elements, Precursors for Novel Glasses and Ceramics

DTIC Science & Technology

1990-08-01

OF TABLES v LIST OF FIGURES vi 1. ABSTRACT 1 2. INTRODUCTION 3 3. RESULTS AND DISCUSSION 5 3.1 Synthesis and Thermolysis of Aluminum...Chloride.Hexamethyldisilazane Adduct 5 3.2 Synthesis and Reactions of Bis(trimethylsilyl)- aminoaluminum Compounds 11 3.3 Reactions of Tris[bis(trimethylsilyl)amino...Et3N.C12AIN(SiMe3 )B(NH2 )NHSiMe3 , a processible precursor to AlN.BN ceramic. Attempts at synthesis of other AlN.BN precursors and AINP systems were

20 CFR 655.1116 - Element VI-What notification must facilities provide to registered nurses?

Code of Federal Regulations, 2010 CFR

2010-04-01

... provide to registered nurses? 655.1116 Section 655.1116 Employees' Benefits EMPLOYMENT AND TRAINING... Requirements Must a Facility Meet to Employ H-1C Nonimmigrant Workers as Registered Nurses? § 655.1116 Element VI—What notification must facilities provide to registered nurses? (a) The sixth attestation element...

20 CFR 655.1116 - Element VI-What notification must facilities provide to registered nurses?

Code of Federal Regulations, 2011 CFR

2011-04-01

... provide to registered nurses? 655.1116 Section 655.1116 Employees' Benefits EMPLOYMENT AND TRAINING... Requirements Must a Facility Meet to Employ H-1C Nonimmigrant Workers as Registered Nurses? § 655.1116 Element VI—What notification must facilities provide to registered nurses? (a) The sixth attestation element...

An exploratory study on low-concentration hexavalent chromium adsorption by Fe(III)-cross-linked chitosan beads

PubMed Central

Zhang, Yuanjing; Qian, Jin; Xin, Xu; Hu, Sihai; Zhang, Shuai; Wei, Jianguo

2017-01-01

In this study, Fe(III)-cross-linked chitosan beads (Fe(III)-CBs) were synthesized and employed to explore the characteristics and primary mechanism of their hexavalent chromium (Cr(VI)) adsorption under low concentration Cr(VI) (less than 20.0 mg l−1) and a pH range from 2.0 to 8.0. Batch tests were conducted to determine the Cr(VI) adsorption capacity and kinetics, and the effects of pH and temperature on the adsorption under low concentration Cr(VI) and a pH range from 2.0 to 8.0. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy were employed to explore the characteristics of Fe(III)-CBs and their Cr(VI) adsorption mechanisms. The results show that, unlike the adsorption of other absorbents, the Cr(VI) adsorption was efficient in a wide pH range from 2.0 to 6.0, and well described by the pseudo-first-order model and the Langmuir–Freundlich isotherm model. The capacity of Cr(VI) adsorption by Fe(III)-CBs was as high as 166.3 mg g−1 under temperature 25°C and pH 6.0. The desorption test was also carried out by 0.1 mol l−1 NaOH solution for Fe(III)-CBs regeneration. It was found that Fe(III)-CBs could be re-used for five adsorption–desorption cycles without significant decrease in Cr(VI) adsorption capacity. Ion exchange was confirmed between functional groups (i.e. amino group) and Cr(VI) anions (i.e. CrO42−). The amino-like functional groups played a key role in Cr(VI) distribution on the Fe(III)-CBs surface; Cr(VI) adsorbed on Fe(III)-CBs was partially reduced to Cr(III) with alcoholic group served as electron donor, and then formed another rate-limiting factor. So, Fe(III)-CBs has a good prospect in purifying low concentration Cr(VI) water with a pH range from 2.0 to 6.0. PMID:29291084

40 CFR 80.614 - What are the alternative defense requirements in lieu of § 80.613(a)(1)(vi)?

Code of Federal Regulations, 2010 CFR

2010-07-01

... the additive package has been added, together with supporting data which includes one of the following... a MVNRLM diesel fuel additive package into MVNRLM diesel fuel subject to the 15 ppm sulfur standards... alternative to the defense element under § 80.613(a)(1)(vi): (a)(1) The blender of the additive package has a...

40 CFR 80.614 - What are the alternative defense requirements in lieu of § 80.613(a)(1)(vi)?

Code of Federal Regulations, 2012 CFR

2012-07-01

... the additive package has been added, together with supporting data which includes one of the following... a MVNRLM diesel fuel additive package into MVNRLM diesel fuel subject to the 15 ppm sulfur standards... alternative to the defense element under § 80.613(a)(1)(vi): (a)(1) The blender of the additive package has a...

40 CFR 80.614 - What are the alternative defense requirements in lieu of § 80.613(a)(1)(vi)?

Code of Federal Regulations, 2014 CFR

2014-07-01

... the additive package has been added, together with supporting data which includes one of the following... a MVNRLM diesel fuel additive package into MVNRLM diesel fuel subject to the 15 ppm sulfur standards... alternative to the defense element under § 80.613(a)(1)(vi): (a)(1) The blender of the additive package has a...

40 CFR 80.614 - What are the alternative defense requirements in lieu of § 80.613(a)(1)(vi)?

Code of Federal Regulations, 2013 CFR

2013-07-01

... the additive package has been added, together with supporting data which includes one of the following... a MVNRLM diesel fuel additive package into MVNRLM diesel fuel subject to the 15 ppm sulfur standards... alternative to the defense element under § 80.613(a)(1)(vi): (a)(1) The blender of the additive package has a...

40 CFR 80.614 - What are the alternative defense requirements in lieu of § 80.613(a)(1)(vi)?

Code of Federal Regulations, 2011 CFR

2011-07-01

... the additive package has been added, together with supporting data which includes one of the following... a MVNRLM diesel fuel additive package into MVNRLM diesel fuel subject to the 15 ppm sulfur standards... alternative to the defense element under § 80.613(a)(1)(vi): (a)(1) The blender of the additive package has a...

Reduction and removal of Cr(VI) from aqueous solutions using modified byproducts of beer production.

PubMed

Cui, Haojie; Fu, Minglai; Yu, Shen; Wang, Ming Kuang

2011-02-28

Biosorption, as an effective and low-cost technology treating industrial wastewaters containing Cr(VI), has become a significant concern worldwide. In this work, acid-modified byproducts of beer production (BBP) were used to remove Cr(VI) from aqueous solutions. Removal of Cr(VI) increases as the pH is decreased from 4.0 to 1.5, but the maximum of total Cr removal is obtained in a pH range from 2.0 to 2.5. Nearly 60% of the initial Cr(VI) (100 mg L(-1)) was adsorbed or reduced to Cr(III) within the first 10 min at pH 2.0. The Cr(VI) removal capability of acid-modified BBP materials was almost completely retained after regenerating with acid. FT-IR and XPS spectra revealed that carboxylate and carboxyl groups on the surface of modified BBP materials play a major role in Cr(VI) binding and reduction, whereas amide and other groups play a minor role in the Cr(VI) removal process. Copyright © 2010 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2017-02-01

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

Serological response following re-vaccination with Salmonella typhi Vi-capsular polysaccharide vaccines in healthy adult travellers.

PubMed

Roggelin, Louise; Vinnemeier, Christof D; Fischer-Herr, Johanna; Johnson-Weaver, Brandi T; Rolling, Thierry; Burchard, Gerd D; Staats, Herman F; Cramer, Jakob P

2015-08-07

An injectable Vi-capsular polysaccharide vaccine against typhoid fever is available but vaccine-induced immunity tends to wane over time. The phenomenon of immunotolerance or hyporesponsiveness has earlier been described for polysaccharide vaccines such as pneumococcal capsular polysaccharide vaccine and some publications also suggest a possible immunotolerance after revaccination with Vi-capsular polysaccharide vaccines. In this study, post-immunisation antibody concentrations in adult travellers first vaccinated with a Salmonella typhi Vi-capsular polysaccharide vaccine (primary vaccination group) were compared with those having received one or more vaccinations previously (multiple vaccinations group). Vaccines administered were Typherix(®) (GlaxoSmithKline), Typhim Vi(®) (Sanofi Pasteur MSD) or Hepatyrix(®) (GlaxoSmithKline). Blood samples were obtained prior to vaccination (day 0) and on day 28 (-1/+14) after vaccination. Serum Vi-Antigen IgG concentrations were measured by ELISA. Of the 85 subjects included in the per protocol data set, 45 (53%) belonged to the multiple vaccinations group. In both groups, geometric mean antibody concentrations (GMCs) were significantly higher after vaccination than before vaccination. Pre-vaccination GMCs were lower in the primary vaccination group than in the multiple vaccinations group (3.40 μg/ml versus 6.13 μg/ml, P=0.005), while there was no significant difference in the post vaccination GMCs between groups (11.34 μg/ml versus 14.58 μg/ml, P=0.4). In the multiple vaccinations group, vaccination was performed 18 to 57 months after the last vaccination (median 38 months) and there was a negative correlation between time since last vaccination and antibody concentration on day 0. In conclusion, we were not able to demonstrate a relevant immunotolerance after multiple versus primary vaccination with S. typhi Vi-capsular polysaccharide vaccines. Copyright © 2015 Elsevier Ltd. All rights reserved.

Se(VI) Reduction and the Precipitation of Se(0) Precipitation by the Facultative Bacterium Enterobacter Cloacae SLD1a-1 is Regulated by FNR

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

Yee,N.; Ma, J.; Dalia, A.

2007-01-01

The fate of selenium in the environment is controlled, in part, by microbial selenium oxyanion reduction and Se(0) precipitation. In this study, we identified a genetic regulator that controls selenate reductase activity in the Se-reducing bacterium Enterobacter cloacae SLD1a-1. Heterologous expression of the global anaerobic regulatory gene fnr (fumarate nitrate reduction regulator) from E. cloacae in the non-Se-reducing strain Escherichia coli S17-1 activated the ability to reduce Se(VI) and precipitate insoluble Se(0) particles. Se(VI) reduction by E. coli S17-1 containing the fnr gene occurred at rates similar to those for E. cloacae, with first-order reaction constants of k = 2.07more » x 10{sup -2} h{sup -1} and k = 3.36 x 10{sup -2} h{sup -1}, respectively, and produced elemental selenium particles with identical morphologies and short-range atomic orders. Mutation of the fnr gene in E. cloacae SLD1a-1 resulted in derivative strains that were deficient in selenate reductase activity and unable to precipitate elemental selenium. Complementation by the wild-type fnr sequence restored the ability of mutant strains to reduce Se(VI). Our findings suggest that Se(VI) reduction and the precipitation of Se(0) by facultative anaerobes are regulated by oxygen-sensing transcription factors and occur under suboxic conditions.« less

In-situ evidence for uranium immobilization and remobilization

USGS Publications Warehouse

Senko, John M.; Istok, Jonathan D.; Suflita, Joseph M.; Krumholz, Lee R.

2002-01-01

The in-situ microbial reduction and immobilization of uranium was assessed as a means of preventing the migration of this element in the terrestrial subsurface. Uranium immobilization (putatively identified as reduction) and microbial respiratory activities were evaluated in the presence of exogenous electron donors and acceptors with field push−pull tests using wells installed in an anoxic aquifer contaminated with landfill leachate. Uranium(VI) amended at 1.5 μM was reduced to less than 1 nM in groundwater in less than 8 d during all field experiments. Amendments of 0.5 mM sulfate or 5 mM nitrate slowed U(VI) immobilization and allowed for the recovery of 10% and 54% of the injected element, respectively, as compared to 4% in the unamended treatment. Laboratory incubations confirmed the field tests and showed that the majority of the U(VI) immobilized was due to microbial reduction. In these tests, nitrate treatment (7.5 mM) inhibited U(VI) reduction, and nitrite was transiently produced. Further push−pull tests were performed in which either 1 or 5 mM nitrate was added with 1.0 μM U(VI) to sediments that already contained immobilized uranium. After an initial loss of the amendments, the concentration of soluble U(VI) increased and eventually exceeded the injected concentration, indicating that previously immobilized uranium was remobilized as nitrate was reduced. Laboratory experiments using heat-inactivated sediment slurries suggested that the intermediates of dissimilatory nitrate reduction (denitrification or dissimilatory nitrate reduction to ammonia), nitrite, nitrous oxide, and nitric oxide were all capable of oxidizing and mobilizing U(IV). These findings indicate that in-situ subsurface U(VI) immobilization can be expected to take place under anaerobic conditions, but the permanence of the approach can be impaired by disimilatory nitrate reduction intermediates that can mobilize previously reduced uranium.

[A study of Ververck index in 16 865 singleton neonates with a gestational age of 27-42 weeks in Shenzhen, China].

PubMed

Huang, Xiao-Yun; Liu, Hui-Long; Lei, Min; Lian, Zhao-Hui; Mai, Hui-Fen

2018-01-01

Ververck index (VI) reflects thoracic development, body type, and nutritional status. This study aimed to investigate the VI of singleton neonates with a gestational age (GA) of 27-42 weeks at birth, and to establish percentile curves of VI of the neonates. Cross-sectional cluster sampling was performed between April 2013 and September 2015. Body weight, body length, and chest circumference were measured for 16 865 singleton neonates with a GA of 27-42 weeks in two hospitals in Shenzhen, China. VI was calculated and the percentile curves of VI were plotted for the neonates. Mean VIs were obtained for singleton neonates with a gestational age of 27-42 weeks (in three groups of male, female, and both sexes), and related 3rd-97th percentile curves were plotted. As for the 50th percentile curve, the singleton neonates with a GA of 27 weeks had the lowest 50th percentile value of VI, which gradually increased with the increase in GA. The singleton neonates with a GA of 42 weeks had the highest 50th percentile value of VI. Girls had a slightly higher 50th percentile value of VI than boys in all GA groups. VI of neonates increases with the increase in GA. Female neonates may have a slightly better thoracic development, body type, and nutritional status than male neonates at birth. The percentile curves of VI plotted for singleton neonates with a GA of 27-42 weeks (in three groups of male, female, and both sexes) can provide a basis for evaluating thoracic development, body type, and nutritional status of neonates at birth in Shenzhen, China.

Comparative Study of Chromium(VI) Removal from Simulated Industrial Wastewater with Ion Exchange Resins

NASA Astrophysics Data System (ADS)

Li, Xiaofan; Shi, Shaoyuan; Cao, Hongbin; Li, Yuping; Xu, Dongyao

2018-06-01

Ion exchange process is an alternative technique for removal of heavy metal ions from industrial wastewater. The main aim of this paper is to evaluate the performance of different ion exchange resins in removing Cr(VI) from wastewater. The effects of resin types and dosage, initial pH were examined systemically. The results showed that the performance of different resins had obvious difference for the removal of the Cr(VI) ions, in which the type of functional groups of the resin was the main factor. The SEM images indicated that the micro-morphology of resins before and after adsorption of the Cr(VI) presented a little difference. The EDS analysis showed that the adsorbed Cr(VI) was uniformly distributed at the surface of the resins with formation of oxygen-containing groups. The adsorption isotherms and kinetics of Cr(VI) by the different resins are also discussed.

Removal of hexavalent chromium upon interaction with biochar under acidic conditions: mechanistic insights and application.

PubMed

Choudhary, Bharat; Paul, Debajyoti; Singh, Abhas; Gupta, Tarun

2017-07-01

Chromium pollution of soil and water is a serious environmental concern due to potential carcinogenicity of hexavalent chromium [Cr(VI)] when ingested. Eucalyptus bark biochar (EBB), a carbonaceous black porous material obtained by pyrolysis of biomass at 500 °C under oxygen-free atmosphere, was used to investigate the removal of aqueous Cr(VI) upon interaction with the EBB, the dominant Cr(VI) removal mechanism(s), and the applicability to treat Cr(VI)-contaminated wastewater. Batch experiments showed complete removal of aqueous Cr(VI) at pH 1-2; sorption was negligible at pH 1, but ~55% of total Cr was sorbed onto the EBB surface at pH 2. Detailed investigations on unreacted and reacted EBB through Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry (XPS) indicate that the carboxylic groups in biochar played a dominant role in Cr(VI) sorption, whereas the phenolic groups were responsible for Cr(VI) reduction. The predominance of sorption-reduction mechanism was confirmed by XPS studies that indicated ~82% as Cr(III) and ~18% as Cr(VI) sorbed on the EBB surface. Significantly, Cr(VI) reduction was also facilitated by dissolved organic matter (DOM) extracted from biochar. This reduction was enhanced by the presence of biochar. Overall, the removal of Cr(VI) in the presence of biochar was affected by sorption due to electrostatic attraction, sorption-reduction mediated by surface organic complexes, and aqueous reduction by DOM. Relative dominance of the aqueous reduction mechanism depended on a critical biochar dosage for a given electrolyte pH and initial Cr(VI) concentration. The low-cost EBB developed here successfully removed all Cr(VI) in chrome tanning acidic wastewater and Cr(VI)-contaminated groundwater after pH adjustment, highlighting its potential applicability in effective Cr(VI) remediation.

Development of the chromatographic partitioning of cesium and strontium utilizing two macroporous silica-based calix[4]arene-crown and amide impregnated polymeric composites: PREC partitioning process.

PubMed

Zhang, Anyun; Kuraoka, Etsushu; Kumagai, Mikio

2007-07-20

To partition effectively Cs(I) and Sr(II), two harmful heat emitting nuclides, from a highly active liquid waste by extraction chromatography, two kinds of macroporous silica-based polymeric materials, Calix[4]arene-R14/SiO(2)-P and TODGA/SiO(2)-P, were synthesized. Two chelating agents, 1,3-[(2,4-diethyl-heptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14), an excellent supramolecular compound having molecular recognition ability for Cs(I), and N,N,N',N'-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) were impregnated and immobilized into the pores of SiO(2)-P particles support by a vacuum sucking technique. The loading and elution of 11 typical simulated fission and non-fission products from 4.0M or 2.0M HNO(3) were performed at 298K. It was found that in the first column packed with the Calix[4]arene-R14/SiO(2)-P, all of the simulated elements were separated effectively into two groups: (1) Na(I), K(I), Sr(II), Fe(III), Ba(II), Ru(III), Pd(II), Zr(IV), and Mo(VI) (noted as Sr-group); (2) Cs(I)-Rb(I) (Cs-group) by eluting with 4.0M HNO(3) and distilled water, respectively. The harmful element Cs(I) flowed into the second group along with Rb(I) because of their close sorption and elution properties towards Calix[4]arene-R14/SiO(2)-P, while Sr(II) showed no sorption and flowed into Sr-containing group. In the second column packed with TODGA/SiO(2)-P, the Sr-group was separated into (1) Ba(II), Ru(III), Na(I), K(I), Fe(III), and Mo(VI) (non-sorption group); (2) Sr(II); (3) Pd(II); and (4) Zr(IV) by eluting with 2.0M HNO(3), 0.01M HNO(3), 0.05M DTPA-pH 2.5, and 0.5M H(2)C(2)O(4), respectively. Sr(II) adsorbed towards TODGA/SiO(2)-P flowed into the second group and showed the excellent separation efficiency from others. Based on the elution behavior of the tested elements, an advanced PREC (Partitioning and Recovery of two heat generators from an acidic HLW (high activity liquid waste) by Extraction Chromatography) process was proposed.

Bullying prevention in schools by targeting cognitions, emotions, and behavior: Evaluating the effectiveness of the REBE-ViSC program.

PubMed

Trip, Simona; Bora, Carmen; Sipos-Gug, Sebastian; Tocai, Ioana; Gradinger, Petra; Yanagida, Takuya; Strohmeier, Dagmar

2015-10-01

The effectiveness of a class-based antibullying prevention program on cognitions, emotions, and behaviors was investigated. The program consists of a cognitive-behavioral (Rational Emotive Behavioral Education; REBE) and a behavioral (Viennese Social Competence; ViSC) component. The REBE program is based on rational emotive behavioral theory and contains 9 student lessons. The ViSC program is based on social learning theory and comprises 10 student lessons. The order of the programs was experimentally manipulated. The REBE-ViSC program was implemented in 5 schools (14 classes), the ViSC-REBE program was implemented in 3 schools (9 classes), and 3 schools (11 classes) served as an untreated control group. Data were collected during 1 school year at pretest, midpoint, and posttest. Emotions (overt and internalizing anger), cognitions (learning and entitlement), and behaviors (bullying perpetration and bullying victimization) were measured with self-assessments. To examine the effectiveness of the REBE-ViSC/ViSC-REBE program, multilevel growth models were applied (time points at Level 1, individuals at Level 2, and classes at Level 3). The analyses revealed that the program effects differed depending on the order of the programs. The REBE-ViSC condition was more effective in changing negative emotions than the ViSC-REBE condition; both experimental conditions were effective in reducing dysfunctional cognitions, whereas no behavioral change was found in the 2 experimental groups when compared with the control group. To improve program effectiveness regarding behavioral changes, a multilevel whole-school approach including a teacher component is recommended. (c) 2015 APA, all rights reserved).

Effect of exogenous melatonin and different photoperiods on oxidative status and antioxidant enzyme activity in Chhotanagpuri ewe.

PubMed

Choudhary, Pankaj Kumar; Ishwar, Ajay Kumar; Kumar, Rajesh; Niyogi, Debasish; Kumar, Mukesh

2018-02-01

The present study was conducted to evaluate the effect of exogenous melatonin under different photoperiods on oxidative status in Chhotanagpuri ewe. A total of 42 non-pregnant, non-lactating Chhotanagpuri ewe, having body weight ranging between 14.11±0.09 and 15.38±0.06 kg, were selected and were isolated from rams 2 months before melatonin administration. The selected animals were allocated randomly into seven groups, namely, Group I (normal control), Group II (long day [LD] control), Group III (LD+melatonin administration orally, 3 mg/day), Group IV (LD+melatonin administration subcutaneously, 1 mg/day), Group V (short day [SD] control), Group VI (SD+melatonin administration orally, 3 mg/day), and Group VII (SD+melatonin administration subcutaneously, 1 mg/day) comprising six animals in each group. Rams were then introduced into each group after completion of exogenous administration of melatonin. Blood samples with anticoagulant in vials were collected from each animal day before the start of the experiment and thereafter every month up to 5 th month. Hemolysate was prepared for estimation of oxidative stress parameters such as malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT). It was observed that the level of MDA was significantly (p<0.05) higher in LD groups (Group II, III and IV) in comparison to control and SD groups (VI and VII) at 1 st month. MDA concentration after exogenous administration of melatonin was significantly (p<0.05) decreased in Group IV and VI in comparison to 1 st month. SOD was significantly (p<0.05) higher in SD groups (V, VI, and VII) at the 1 st month in comparison to 0 day. After exogenous administration of melatonin, SOD concentration was significantly (p<0.05) higher in Groups III and IV in comparison to 1 st month. CAT was significantly (p<0.05) higher in SD groups (V, VI, and VII) in comparison to control and LD groups. After exogenous administration of melatonin, CAT concentration was significantly (p<0.05) higher in Groups III, IV, VI, and VIII in comparison to Groups I, II, and V. At the 3 rd month, CAT concentration significantly (p<0.05) decreased in Groups III, IV, VI, and VII in comparison to 2 nd month of experiment. However, a decreasing trend of CAT was observed in all the groups from 3 rd to 5 th month. The present experiment revealed that exogenous melatonin was able to reduce significantly the level of MDA and increased the activity of SOD and CAT in Chhotanagpuri ewe.

Recovery of Elemental Tellurium Nanoparticles by the Reduction of Tellurium Oxyanions in a Methanogenic Microbial Consortium.

PubMed

Ramos-Ruiz, Adriana; Field, Jim A; Wilkening, Jean V; Sierra-Alvarez, Reyes

2016-02-02

This research focuses on the microbial recovery of elemental tellurium (Te(0)) from aqueous streams containing soluble tellurium oxyanions, tellurate (Te(VI)), and tellurite (Te(IV)). An anaerobic mixed microbial culture occurring in methanogenic granular sludge was able to biocatalyze the reduction of both Te oxyanions to produce Te(0) nanoparticles (NPs) in sulfur-free medium. Te(IV) reduction was seven times faster than that of Te(VI), such that Te(IV) did not accumulate to a great extent during Te(VI) reduction. Endogenous substrates in the granular sludge provided the electron equivalents required to reduce Te oxyanions; however, the reduction rates were modestly increased with an exogenous electron donor such as H2. The effect of four redox mediators (anthraquinone-2,6-disulfonate, hydroxocobalamin, riboflavin, and lawsone) was also tested. Riboflavin increased the rate of Te(IV) reduction eleven-fold and also enhanced the fraction Te recovered as extracellular Te(0) NPs from 21% to 64%. Lawsone increased the rate of Te(VI) reduction five-fold, and the fraction of Te recovered as extracellular material increased from 49% to 83%. The redox mediators and electron donors also impacted the morphologies and localization of Te(0) NPs, suggesting that NP production can be tailored for a particular application.

Recovery of Elemental Tellurium Nanoparticles by the Reduction of Tellurium Oxyanions in a Methanogenic Microbial Consortium

PubMed Central

Ramos-Ruiz, Adriana; Field, Jim A.; Wilkening, Jean V.; Sierra-Alvarez, Reyes

2016-01-01

This research focuses on the microbial recovery of elemental tellurium (Te0) from aqueous streams containing soluble tellurium oxyanions, tellurate (TeVI) and tellurite (TeIV). An anaerobic mixed microbial culture occurring in methanogenic granular sludge was able to biocatalyze the reduction of both Te oxyanions to produce Te0 nanoparticles (NPs) in sulfur-free medium. TeIV reduction was 7-fold faster than that of TeVI, such that TeIV did not accumulate to a great extent during TeVI reduction. Endogenous substrates in the granular sludge provided the electron equivalents required to reduce Te oxyanions; however, the reduction rates were modestly increased with an exogenous electron donor such as H2. The effect of four redox mediators (anthraquinone-2,6-disulfonate, hydroxocobalamin, riboflavin, and lawsone) was also tested. Riboflavin increased the rate of TeIV reduction by 11-fold and also enhanced the fraction Te recovered as extracellular Te0 NPs from 21% to 64%. Lawsone increased the rate of TeVI reduction by 5-fold and the fraction of Te recovered as extracellular material increased from 49% to 83%. The redox mediators and electron donors also impacted the morphologies and localization of Te0 NPs, suggesting that NP production can be tailored for a particular application. PMID:26735010

Tetradymites as thermoelectrics and topological insulators

NASA Astrophysics Data System (ADS)

Heremans, Joseph P.; Cava, Robert J.; Samarth, Nitin

2017-10-01

Tetradymites are M2X3 compounds — in which M is a group V metal, usually Bi or Sb, and X is a group VI anion, Te, Se or S — that crystallize in a rhombohedral structure. Bi2Se3, Bi2Te3 and Sb2Te3 are archetypical tetradymites. Other mixtures of M and X elements produce common variants, such as Bi2Te2Se. Because tetradymites are based on heavy p-block elements, strong spin-orbit coupling greatly influences their electronic properties, both on the surface and in the bulk. Their surface electronic states are a cornerstone of frontier work on topological insulators. The bulk energy bands are characterized by small energy gaps, high group velocities, small effective masses and band inversion near the centre of the Brillouin zone. These properties are favourable for high-efficiency thermoelectric materials but make it difficult to obtain an electrically insulating bulk, which is a requirement of topological insulators. This Review outlines recent progress made in bulk and thin-film tetradymite materials for the optimization of their properties both as thermoelectrics and as topological insulators.

Thermoelectric materials having porosity

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

Heremans, Joseph P.; Jaworski, Christopher M.; Jovovic, Vladimir

A thermoelectric material and a method of making a thermoelectric material are provided. In certain embodiments, the thermoelectric material comprises at least 10 volume percent porosity. In some embodiments, the thermoelectric material has a zT greater than about 1.2 at a temperature of about 375 K. In some embodiments, the thermoelectric material comprises a topological thermoelectric material. In some embodiments, the thermoelectric material comprises a general composition of (Bi.sub.1-xSb.sub.x).sub.u(Te.sub.1-ySe.sub.y).sub.w, wherein 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1, 1.8.ltoreq.u.ltoreq.2.2, 2.8.ltoreq.w.ltoreq.3.2. In further embodiments, the thermoelectric material includes a compound having at least one group IV element and at least one group VI element. In certain embodiments,more » the method includes providing a powder comprising a thermoelectric composition, pressing the powder, and sintering the powder to form the thermoelectric material.« less

Graded core/shell semiconductor nanorods and nanorod barcodes

DOEpatents

Alivisatos, A Paul [Oakland, CA; Scher, Erik C [San Francisco, CA; Manna, Liberato [Palo Del Collie, IT

2009-05-19

Disclosed herein is a graded core/shell semiconductor nanorod having at least a first segment of a core of a Group II-VI, Group III-V or a Group IV semiconductor, a graded shell overlying the core, wherein the graded shell comprises at least two monolayers, wherein the at least two monolayers each independently comprise a Group II-VI, Group III-V or a Group IV semiconductor.

Single-layer group IV-V and group V-IV-III-VI semiconductors: Structural stability, electronic structures, optical properties, and photocatalysis

NASA Astrophysics Data System (ADS)

Lin, Jia-He; Zhang, Hong; Cheng, Xin-Lu; Miyamoto, Yoshiyuki

2017-07-01

Recently, single-layer group III monochalcogenides have attracted both theoretical and experimental interest at their potential applications in photonic devices, electronic devices, and solar energy conversion. Excited by this, we theoretically design two kinds of highly stable single-layer group IV-V (IV =Si ,Ge , and Sn; V =N and P) and group V-IV-III-VI (IV =Si ,Ge , and Sn; V =N and P; III =Al ,Ga , and In; VI =O and S) compounds with the same structures with single-layer group III monochalcogenides via first-principles simulations. By using accurate hybrid functional and quasiparticle methods, we show the single-layer group IV-V and group V-IV-III-VI are indirect bandgap semiconductors with their bandgaps and band edge positions conforming to the criteria of photocatalysts for water splitting. By applying a biaxial strain on single-layer group IV-V, single-layer group IV nitrides show a potential on mechanical sensors due to their bandgaps showing an almost linear response for strain. Furthermore, our calculations show that both single-layer group IV-V and group V-IV-III-VI have absorption from the visible light region to far-ultraviolet region, especially for single-layer SiN-AlO and SnN-InO, which have strong absorption in the visible light region, resulting in excellent potential for solar energy conversion and visible light photocatalytic water splitting. Our research provides valuable insight for finding more potential functional two-dimensional semiconductors applied in optoelectronics, solar energy conversion, and photocatalytic water splitting.

Clinical evaluation of complete solo surgery with the "ViKY®" robotic laparoscope manipulator.

PubMed

Takahashi, Masahiro; Takahashi, Masanori; Nishinari, Naoto; Matsuya, Hideki; Tosha, Tsutomu; Minagawa, Yukihiro; Shimooki, Osamu; Abe, Tadashi

2017-02-01

Advancement in both surgical technique and medical equipment has enabled solo surgery. ViKY ® Endoscope Positioning System (ViKY ® ) is a robotic system that remotely controls an endoscope and provides direct vision control to the surgeon. Here, we report our experience with ViKY ® -assisted solo surgery. We retrospectively examined 25 cases of solo surgery TAPP with ViKY ® . ViKY ® was setup by the surgeon alone, and the setup duration was determined as the time at which the side rail was positioned and that when the endoscope was installed. For assessing the control unit, the number of false movements was counted. We compared the operative results between ViKY ® -assisted solo surgery TAPP and the conventional method with an assistant. The average time to set up ViKY ® was 7.9 min. The average number of commands for ViKY ® during surgery was 98.3, and the average number of errors and no response of control unit was 7.9. The mean duration of surgery was 136 min for the ViKY ® group, including the setup time, and 117 min for the conventional method. No case required an assistant during the operation. There was also no difference between the two groups with regard to postoperative complications and the rate of recurrence. ViKY ® proved reliable in recognizing orders with very few failures, and the operations were performed safely and were comparable to the conventional operations with assistants. Solo surgery with ViKY ® was beneficial in this clinical evaluation.

Macroscopic and Microscopic Investigation of U(VI) and Eu(III) Adsorption on Carbonaceous Nanofibers.

PubMed

Sun, Yubing; Wu, Zhen-Yu; Wang, Xiangxue; Ding, Congcong; Cheng, Wencai; Yu, Shu-Hong; Wang, Xiangke

2016-04-19

The adsorption mechanism of U(VI) and Eu(III) on carbonaceous nanofibers (CNFs) was investigated using batch, IR, XPS, XANES, and EXAFS techniques. The pH-dependent adsorption indicated that the adsorption of U(VI) on the CNFs was significantly higher than the adsorption of Eu(III) at pH < 7.0. The maximum adsorption capacity of the CNFs calculated from the Langmuir model at pH 4.5 and 298 K for U(VI) and Eu(III) were 125 and 91 mg/g, respectively. The CNFs displayed good recyclability and recoverability by regeneration experiments. Based on XPS and XANES analyses, the enrichment of U(VI) and Eu(III) was attributed to the abundant adsorption sites (e.g., -OH and -COOH groups) of the CNFs. IR analysis further demonstrated that -COOH groups were more responsible for U(VI) adsorption. In addition, the remarkable reducing agents of the R-CH2OH groups were responsible for the highly efficient adsorption of U(VI) on the CNFs. The adsorption mechanism of U(VI) on the CNFs at pH 4.5 was shifted from inner- to outer-sphere surface complexation with increasing initial concentration, whereas the surface (co)precipitate (i.e., schoepite) was observed at pH 7.0 by EXAFS spectra. The findings presented herein play an important role in the removal of radionuclides on inexpensive and available carbon-based nanoparticles in environmental cleanup applications.

Measuring Elemental Abundances in Impulsive Heating Events with EIS

NASA Astrophysics Data System (ADS)

Warren, Harry; Doschek, George A.; Young, Peter

2015-04-01

It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have indicated that in the solar corona low FIP elements, such as Fe, Si, and Mg, are enriched relative to high FIP elements, such as H, He, C, N, and O. In this paper we report on measurements of plasma composition made during transient heating events observed at transition region temperatures with the Extreme Ultraviolet Imaging Spectrometer (EIS) on Hinode. During these events the intensities of O IV, V, and VI emission lines are enhanced relative to emission lines from Mg V, VI, and VII and indicate a composition close to that of the photosphere. Differential emission measure calculations show a broad distribution of temperatures in these events. Long-lived coronal structures, in contrast, show an enrichment of low FIP elements and relatively narrow temperature distributions. We conjecture that plasma composition is an important signature of the coronal heating process, with impulsive heating leading to the evaporation of unfractionated material from the lower layers of the solar atmosphere and higher frequency heating leading to the accumulation of low-FIP elements in the corona.

Vacuum infusion method for woven carbon/Kevlar reinforced hybrid composite

NASA Astrophysics Data System (ADS)

Hashim, N.; Majid, D. L.; Uda, N.; Zahari, R.; Yidris, N.

2017-12-01

The vacuum assisted resin transfer moulding (VaRTM) or Vacuum Infusion (VI) is one of the fabrication methods used for composite materials. Compared to other methods, this process costs lower than using prepregs because it does not need to use the autoclave to cure. Moreover, composites fabricated using this VI method exhibit superior mechanical properties than those made through hand layup process. In this study, the VI method is used in fabricating woven carbon/Kevlar fibre cloth with epoxy matrix. This paper reports the detailed methods on fabricating the hybrid composite using VI process and several precautions that need to be taken to avoid any damage to the properties of the composite material. The result highlights that the successfully fabricated composite has approximately 60% of fibres weight fraction. Since the composites produced by the VI process have a higher fibre percentage, this process should be considered for composites used in applications that are susceptible to the conditions where the fibres need to be the dominant element such as in tension loading.

Report of the CCQM-K124: trace elements and chromium speciation in drinking water—part A: trace elements in drinking water, part B: chromium speciation in drinking water

NASA Astrophysics Data System (ADS)

Kuroiwa, T.; Fung, W. H.; Zhu, Y.; Inagaki, K.; Sin, D. W. M.; Chu, H. S.; Saxby, D.; Merrick, J.; White, I.; Araujo, T.; Almeida, M. D.; Rodrigues, J.; Yang, L.; Pihillagawa, I. G.; Mester, Z.; Riquelme, S. S.; Pérez, L.; Barriga, R.; Núñez, C.; Chao, J.; Wang, J.; Wang, Q.; Shi, N.; Lu, H.; Song, P.; Nüykki, T.; Aho, T. Sara; Labarraque, G.; Oster, C.; Rienitz, O.; Jührling, R.; Pape, C.; Lampi, E.; Kakoulides, E.; Ketrin, R.; Mardika, E.; Komalasari, I.; Okumu, T. O.; Kang'iri, J. N.; Yim, Y. H.; Heo, S. W.; Lee, K. S.; Suh, J. K.; Lim, Y.; Manzano, J. V. L.; Uribe, C.; Carrasco, E.; Tayag, E. D.; Dablio, A. R. C.; Encarnacion, E. K. P.; Damian, R. L.; Konopelko, L.; Krylov, A.; Vadim, S.; Shin, R.; Peng, S. L.; Juan, W.; Chang, X.; Dewi, F.; Horvat, M.; Zuliani, T.; Taebunpakul, S.; Yafa, C.; Kaewkhomdee, N.; Thiengmanee, U.; Klich, H.; Can, S. Z.; Ari, B.; Cankur, O.; Goenaga Infante, H.; Ferreira, E.; Pérez, R.; E Long, S.; Kassim, B. L.; E Murphy, K.; Molloy, J. L.; Butler, T. A.

2017-01-01

CCQM-K124 was organized by the Inorganic Analysis Working Group (IAWG) of CCQM to assess and document the capabilities of the national metrology institutes (NMIs) or the designated institutes (DIs) to measure the mass fractions of trace elements (As, B, Cd, Ca, Cr, Hg and Mo) and hexavalent chromium (Cr(VI)) in drinking water. The National Metrology Institute of Japan (NMIJ) and the Government Laboratory, Hong Kong SAR (GLHK) acted as the coordinating laboratories. This comparison is divided into two parts. Part A was organized by the NMIJ and the trace elements were the analytes, and Part B was organised by the GLHK and Cr(VI) was the analyte. In Part A, results were submitted by 14 NMIs and nine DIs. The participants used different measurement methods, though most of them used direct measurement using inductively coupled plasma-optical emission spectrometry (ICP-OES), inductively coupled plasma-mass spectrometry (ICP-MS), and isotope dilution technique with ICP-MS. The results of As, B, Cd, Ca and Cr show good agreement with the exception of some outliers. Concerning Hg, instability was observed when the sample was stored in the light. And some participants observed instability of Mo. Therefore, it was agreed to abandon the Hg and Mo analysis as this sample was not satisfactory for KC. In Part B, results were submitted by six NMIs and one DI. The methods applied were direct measurement using 1,5-diphenylcarbazide (DPC) derivatisation UV-visible spectrophotometry, standard addition using ion chromatography-UV-visible spectrophotometry or HPLC—inductively coupled plasma-mass spectrometry (ICP-MS) and isotope dilution technique with ion chromatography—ICP-MS. The results of all participants show good agreement. Accounting for relative expanded uncertainty, comparability of measurement results for each of As, B, Cd, Ca, Cr and Cr(VI) was successfully demonstrated by the participating NMIs or DIs. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The Relationship between Visual Impairment and Health-Related Quality of Life in Korean Adults: The Korea National Health and Nutrition Examination Survey (2008–2012)

PubMed Central

Park, Yuli; Shin, Jeong Ah; Yang, Suk Woo; Yim, Hyeon Woo; Kim, Hyun Seung; Park, Young-Hoon

2015-01-01

Introduction To evaluate health-related quality of life (HRQoL) in Korean adults with visual impairment(VI) using various measures based on a nationally distributed sample. Methods Using the Korea National Health and Nutrition Examination Survey (KNHANES, 2008–2012) data, we compared EuroQol five-dimensional questionnaire (EQ-5D) and EQ-visual analogue scale (VAS) scores after adjusting for socio-demographic and psychosocial factors as well as for comorbidities with VI. Logistic regressions were used to elucidate determinants for the lowest quintile HRQoL scales according to VI severity. Uncorrected visual acuity (VA) which implies vision of ordinary life was measured using an international standard vision chart based on Snellen scale. Results 28,825 participants (sum of weights; 37,562,376) were included in the analysis. The mean EQ-5D and EQ-VAS scores were significantly lower in the VI groups than in the normal vision (defined as VA 20/20-20/25) group based on the better or worse seeing eye (P<.0001 and P<.0001, respectively). Participants with moderate (VA 20/80-20/160) and severe VI (VA ≤20/200) had higher scores of multivariate-adjusted odd ratios (aORs) for the lowest quintile than did the normal vision group which was particularly evident in the results from EQ-5D, whereas the results of the mild VI (VA 20/32-20/63) group did not identify significant differences from the normal vision group independent of classification according to the better or the worse seeing eye. Conversely, EQ-VAS revealed significantly higher score of multivariate-aORs for the lowest quintile in participants with mild VI either for the better or worse seeing eye. Conclusions The severity of VI was definitely associated with impaired HRQoL compared with the normal vision population. The analyses presented here elicited even mild VI could potentially deteriorate the health-related quality of life (or subjective perception of health quality) and therefore, therapeutic approaches should also focus on the subjective perception and better management of health condition. PMID:26192763

Effects of low-level laser therapy on stem cells from human exfoliated deciduous teeth.

PubMed

Fernandes, Ana Paula; Junqueira, Marina de Azevedo; Marques, Nádia Carolina Teixeira; Machado, Maria Aparecida Andrade Moreira; Santos, Carlos Ferreira; Oliveira, Thais Marchini; Sakai, Vivien Thiemy

2016-01-01

This study aimed to evaluate the influence of different laser therapy energy densities on SHED viability and proliferation. SHED were irradiated according to the groups: I (1.2 J/cm2 - 0.5 mW - 10 s), II (2.5 J/cm2 - 10 mW - 10 s), III (3.7 J/cm2 - 15 mW - 10 s), IV (5.0 J/cm2 - 20 mW - 10 s), V (6.2 J/cm2 - 25 mW - 10 s), and VI (not irradiated - control group). Cell viability was assessed 6 and 24 h after irradiation measuring the mitochondrial activity and using the Crystal Violet assay. Cell proliferation was assessed after 24, 48, and 72 h of irradiation by SRB assay. MTT assay demonstrated differences from 6 to 24 hours after irradiation. After 24 h, groups I and IV showed higher absorbance values than those of control group. Crystal Violet assay showed statistically differences in the absorbance rate from 6 to 24 h after irradiation for groups III and VI. At 24 h after irradiation, Group III absorbance rate was greater than that of groups I, II, and IV. Group VI absorbance rate was greater than that of groups I and IV. SRB assay showed that the group I had higher rates than those of groups II, III, V, and VI, at 24 h after irradiation. After 48 h, group I exhibited the greatest cell proliferation rate followed by groups III, V, and VI. After 72 h, group III exhibited the lowest cell proliferation rate than those of groups II, IV, and V. The Low-Level Laser Therapy energy densities used in this study did not cause loss of cell viability and stimulated SHED proliferation within the parameters described in this study.

The Vi conjugate typhoid vaccine is safe, elicits protective levels of IgG anti-Vi, and is compatible with routine infant vaccines.

PubMed

Thiem, Vu Dinh; Lin, Feng-Ying C; Canh, Do Gia; Son, Nguyen Hong; Anh, Dang Duc; Mao, Nguyen Duc; Chu, Chiayung; Hunt, Steven W; Robbins, John B; Schneerson, Rachel; Szu, Shousun C

2011-05-01

Typhoid fever remains a serious problem in developing countries. Current vaccines are licensed for individuals who are 5 years old or older. A conjugate of the capsular polysaccharide (CP) of Salmonella enterica serovar Typhi (Vi) bound to recombinant exoprotein A of Pseudomonas aeruginosa (Vi-rEPA) enhanced Vi immunogenicity and protected 2- to 5-year-olds in Vietnam. In this study, Vi-rEPA was evaluated for use in infants. A total of 301 full-term Vietnamese infants received Expanded Program on Immunization (EPI) vaccines alone or with Vi-rEPA or Haemophilus influenzae type b-tetanus toxoid conjugate (Hib-TT) at 2, 4, and 6 months and Vi-rEPA or Hib-TT alone at 12 months. Infants were visited 6, 24, and 48 h after each injection to monitor adverse reactions. Maternal, cord, and infant sera were assayed for IgG anti-Vi and for IgG antibodies to Hib CP and the diphtheria, tetanus, and pertussis toxins at 7, 12, and 13 months. No vaccine-related serious adverse reactions occurred. In the Vi-rEPA group, the IgG anti-Vi geometric mean (GM) increased from the cord level of 0.66 to 17.4 enzyme-linked immunosorbent assay units (EU) at 7 months, declined to 4.76 EU at 12 months, and increased to 50.1 EU 1 month after the 4th dose (95% of infants had levels of ≥ 3.5 EU, the estimated protective level). Controls had no increase of the IgG anti-Vi GM. Infants with cord anti-Vi levels of <3.5 EU responded with significantly higher IgG anti-Vi levels than those with levels of ≥ 3.5 EU. Anti-diphtheria, -tetanus, and -pertussis toxin levels were similar in all groups. Vi-rEPA was safe, induced protective anti-Vi levels, and was compatible with EPI vaccines, and it can be used in infants. High cord IgG anti-Vi levels partially suppressed infant responses to Vi-rEPA.

A modified model for calculating lattice thermal expansion of I{sub 2}-IV-VI{sub 3} and I{sub 3}-V-VI{sub 4} tetrahedral compounds

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

Omar, M.S.

2007-05-03

A general empirical formula was found for calculating lattice thermal expansion for compounds having their properties extended for compound groups having different mean ionicity as well as more than one type of cation atoms with that of different numbers of them such as I{sub 2}-IV-VI{sub 3} and I{sub 3}-V-VI{sub 4}. The difference in the valence electrons for cations and anions in the compound was used to correlate the deviations caused by the compound ionicity. The ionicity effects, which are due to their different numbers for their types, were also added to the correlation equation. In general, the lattice thermal expansionmore » for a compound semiconductor can be calculated from a relation containing melting point, mean atomic distance and number of valence electrons for the atoms forming the compound. The mean ionicity for the group compounds forming I{sub 2}-IV-VI{sub 3} was found to be 0.323 and 0.785 for the ternary group compounds of I{sub 3}-V-VI{sub 4}.« less

Efficacy of a novel chelator BPCBG for removing uranium and protecting against uranium-induced renal cell damage in rats and HK-2 cells

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

Bao, Yizhong; Wang, Dan; Li, Zhiming

2013-05-15

Chelation therapy is a known effective method to increase the excretion of U(VI) from the body. Until now, no any uranium chelator has been approved for emergency medical use worldwide. The present study aimed to evaluate the efficacy of new ligand BPCBG containing two catechol groups and two aminocarboxylic acid groups in decorporation of U(VI) and protection against acute U(VI) nephrotoxicity in rats, and further explored the detoxification mechanism of BPCBG for U(VI)-induced nephrotoxicity in HK-2 cells with comparison to DTPA-CaNa{sub 3}. Chelating agents were administered at various times before or after injections of U(VI) in rats. The U(VI) levelsmore » in urine, kidneys and femurs were measured 24 h after U(VI) injections. Histopathological changes in the kidney and serum urea and creatinine and urine protein were examined. After treatment of U(VI)-exposed HK-2 cells with chelating agent, the intracellular U(VI) contents, formation of micronuclei, lactate dehydrogenase (LDH) activity and production of reactive oxygen species (ROS) were assessed. It was found that prompt, advanced or delayed injections of BPCBG effectively increased 24 h-urinary U(VI) excretion and decreased the levels of U(VI) in kidney and bone. Meanwhile, BPCBG injection obviously reduced the severity of the U(VI)-induced histological alterations in the kidney, which was in parallel with the amelioration noted in serum indicators, urea and creatinine, and urine protein of U(VI) nephrotoxicity. In U(VI)-exposed HK-2 cells, immediate and delayed treatment with BPCBG significantly decreased the formation of micronuclei and LDH release by inhibiting the cellular U(VI) intake, promoting the intracellular U(VI) release and inhibiting the production of intracellular ROS. Our data suggest that BPCBG is a novel bi-functional U(VI) decorporation agent with a better efficacy than DTPA-CaNa{sub 3}. - Highlights: ► BPCBG accelerated the urine U(VI) excretion and reduced the tissues U(VI) in rats. ► BPCBG can effectively protect against the U(VI)-induced nephrotoxicity in rats. ► BPCBG increased the U(VI) release and reduced the U(VI) uptake in HK-2 cells. ► BPCBG decreased the U(VI)-induced MN formation and LDH release in HK-2 cells. ► BPCBG eliminated the U(VI)-induced intracellular ROS in HK-2 cells.« less

The influence of Citrosept addition to drinking water and Scutellaria baicalensis root extract on the content of selected mineral elements in the blood plasma of turkey hens.

PubMed

Rusinek-Prystupa, Elżbieta; Lechowski, Jerzy; Zukiewicz-Sobczak, Wioletta; Sobczak, Paweł; Zawiślak, Kazimierz

2014-01-01

The aim of this research work was to indicate the influence of Citrosept preparation and Scutellaria baicalensis root extract, administered per os to growing turkey hens in 3 different dosages, on the content of selected mineral elements in blood plasma of slaughter turkey hens. An attempt was also made to specify the most effective dosage of the applied preparations with the highest efficiency as regards increased levels of examined macro- and microelements in the birds' blood. The research experiment was conducted on 315 turkey hens randomly divided into seven groups, each consisting of 45 turkey hens. Group K constituted the control group without experimental additions of the above-mentioned preparations. When it comes to turkey hens which belonged to groups II-IV, Citrosept preparation was instilled to water in the following dosages: Group II - 0.011 ml/kg of bm; Group III - 0.021 ml/kg of bm; Group IV - 0.042 ml/kg bm. For birds which belonged to groups V-VII preparation, which was Scutellaria baicalensis root extract, was instilled to water in the following dosages: Group V - 0.009 ml/kg of bm; Group VI - 0.018 ml/kg of bm, Group VII - 0.036 ml/kg bm. In the examined plant extracts and blood plasma of the birds the levels of Na, K, Ca, Mg, Cu, Zn, and Fe were identified. The use of examined extracts influenced the changes in the levels of all tested elements in slaughter turkey hens' blood plasma. An upward tendency was recorded which regarded the level of calcium and magnesium, and a downward tendency of sodium, potassium, copper, zinc, and iron in relation to the results achieved in the control group.

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

DOE PAGES

Burns, Jonathan D.; Moyer, Bruce A.

2016-08-17

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

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

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

Burns, Jonathan D.; Moyer, Bruce A.

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

Feasibility of Biological Effective Monitoring of Chrome Electroplaters to Chromium through Analysis of Serum Malondialdehyde.

PubMed

Mozafari, P; Rezazadeh Azari, M; Shokoohi, Y; Sayadi, M

2016-10-01

Great concern about occupational exposure to chromium (Cr [VI]) has been reported due to escalated risk of lung cancer in exposed workers. Consequences of occupational exposure to Cr (VI) have been reported as oxidative stress and lung tissue damage. To investigate the feasibility of biological effect monitoring of chrome electroplaters through analysis of serum malondialdehyde (MDA). 90 workers directly involved in chrome electroplating---categorized into three equal groups based on their job as near bath workers, degreaser, and washers---and 30 workers without exposure to Cr (VI), served as the control group, were studied. Personal samples were collected and analyzed according to NIOSH method 7600. Serum MDA level was measured by HPLC using a UV detector. Median Cr (VI) exposure level was 0.38 mg/m(3) in near bath workers, 0.20 mg/m(3) in degreasers, and 0.05 mg/m(3) in washers. The median serum MDA level of three exposed groups (2.76 μmol/L) was significantly (p<0.001) higher than that in the control group (2.00 μmol/L). There was a positive correlation between electroplaters' level of exposure to Cr (VI) and their serum MDA level (Spearman's ρ 0.806, p<0.001). Serum MDA level is a good biomarker for the level of occupational exposure to Cr (VI) in electroplaters.

Re-examination of immune response and estimation of anti-Vi IgG protective threshold against typhoid fever-based on the efficacy trial of Vi conjugate in young children.

PubMed

Szu, Shousun C; Klugman, Keith P; Hunt, Steven

2014-04-25

The capsular polysaccharide of Salmonella enterica serovar Typhi, Vi antigen, is an essential virulence factor and a protective antigen. Similar to other polysaccharide vaccines, the protective action of Vi, both to the polysaccharide alone or when presented as a conjugate, is mediated by serum IgG Vi antibodies. The evaluation of Vi capsular polysaccharide based vaccines to prevent typhoid fever would be significantly facilitated by the identification of a "protective level" of serum antibodies to Vi antigen. The protective level of anti-Vi IgG against typhoid fever was derived from the protective efficacy and immune response of a Vi-rEPA conjugate vaccine efficacy trial. The estimation was derived by two methods: correlation of the percent efficacy and the antibody distribution profile in the vaccine group at a given period of observation, and use of the relative ratio of anti-Vi IgG levels between the vaccine and placebo groups greater or equal to the Relative Risk of typhoid fever used in the efficacy determination. Both methods predicted a similar range of a minimum protective level of anti-Vi IgG between 1.4 and 2.0μg/ml (short term threshold). When applying a protective threshold of 10μg/ml at 6 months post immunization, an IgG level in excess of 1.4μg/ml was achieved by 90% of children at 46 months post immunization, consistent with an 89% level of protection over the duration of the study. We thus suggest that the proportion of children with Vi IgG>10μg/ml (long term threshold) 6 months after immunization may reflect the proportion protected over at least a 4 year period. The current assignment of an anti-Vi IgG protective level may be of value when evaluating vaccine performance of future Vi conjugate vaccines. Published by Elsevier Ltd.

Re-examination of immune response and estimation of anti-Vi IgG protective threshold against typhoid fever-based on the efficacy trial of Vi conjugate in young children

PubMed Central

Szu, Shousun C.; Klugman, Keith P.; Hunt, Steven

2014-01-01

Background The capsular polysaccharide of Salmonella enterica serovar Typhi, Vi antigen, is an essential virulence factor and a protective antigen. Similar to other polysaccharide vaccines, the protective action of Vi, both to the polysaccharide alone or when presented as a conjugate, is mediated by serum IgG Vi antibodies. The evaluation of Vi capsular polysaccharide based vaccines to prevent typhoid fever would be significantly facilitated by the identification of a “protective level” of serum antibodies to Vi antigen. Methods The protective level of anti-Vi IgG against typhoid fever was derived from the protective efficacy and immune response of a Vi-rEPA conjugate vaccine efficacy trial. The estimation was derived by two methods: correlation of the percent efficacy and the antibody distribution profile in the vaccine group at a given period of observation, and use of the relative ratio of anti-Vi IgG levels between the vaccine and placebo groups greater or equal to the Relative Risk of typhoid fever used in the efficacy determination. Results Both methods predicted a similar range of a minimum protective level of anti-Vi IgG between 1.4 and 2.0 μg/ml (short term threshold). When applying a protective threshold of 10 μg/ml at 6 months post immunization, an IgG level in excess of 1.4 μg/ml was achieved by 90% of children at 46 months post immunization, consistent with an 89% level of protection over the duration of the study. We thus suggest that the proportion of children with Vi IgG > 10 μg/ml (long term threshold) 6 months after immunization may reflect the proportion protected over at least a 4 year period. Conclusion The current assignment of an anti-Vi IgG protective level may be of value when evaluating vaccine performance of future Vi conjugate vaccines. PMID:24630869

Ecotoxicology of Hexavalent Chromium in Freshwater Fish: A Critical Review

PubMed Central

Velma, Venkatramreddy; Vutukuru, S.S.; Tchounwou, Paul B.

2010-01-01

Chromium (Cr) is a naturally occurring element found in rocks, animals, plants, and soil, predominantly in its insoluble trivalent form [Cr(III)]. Intense industrialization and other anthropogenic activities have led to the global occurrence of soluble Cr(VI), which is readily leached from soil to groundwater or surface water, in concentrations above permissible levels. The ecotoxicology of Cr(VI) is linked to its environmental persistence and the ability to induce a variety of adverse effects in biologic systems, including fish. In aquatic ecosystems, Cr(VI) exposure poses a significant threat to aquatic life. This paper reviews the fate and transport of Cr(VI) in the environment and its acute and chronic effects on fish. We also discuss Cr(VI) toxicity at the cellular, biochemical, and genetic levels. An attempt is made in this review to comprehend the staggered data on the toxic effects of Cr(VI) to various species of fish. Such data are extremely useful to the scientific community and public officials involved in health risk assessment and management of environmental contaminants as a guide to the best course of action to restore ecosystems and, in turn, to preserve human health. PMID:19658319

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

Li, Na; Mu, Bao; Lv, Lei

Four new polyoxometalate(POM)–templated metal–organic frameworks based on flexible ligands, namely, [Cu{sub 6}(bip){sub 12}(PMo{sup VI}{sub 12}O{sub 40}){sub 2}(PMo{sup V}Mo{sup VI}{sub 11}O{sub 40}O{sub 2})]·8H{sub 2}O(1), [Cu{sup I}{sub 3}Cu{sup II}{sub 3}(bip){sub 12}(PMo{sup VI}{sub 12}O{sub 40}){sub 2}(PMo{sup V}{sub 12}O{sub 34})]·8H{sub 2}O(2), [Ni{sub 6}(bip){sub 12}(PMo{sup VI}{sub 12}O{sub 40})(PMo{sup VI}{sub 11}Mo{sup V}O{sub 40}){sub 2}]Cl·6H{sub 2}O(3), [Co{sup II}{sub 3}Co{sup III}{sub 2}(H{sub 2}bib){sub 2}(Hbib){sub 2}(PW{sub 9}O{sub 34}){sub 2}(H{sub 2}O){sub 6}]·6H{sub 2}O(4) (bip=1,3-bis(imidazolyl)propane, bib=1,4-bis(imidazolyl)butane) have been obtained under hydrothermal condition and characterized by single-crystal X-ray diffraction analyses, elemental analyses, and thermogravimetric (TG) analyses. The studies of single crystal X-ray indicate that compounds 1–3 crystallize in the trigonal space groupmore » P-3, and compound 4 crystallizes in the triclinic space group P-1. Compounds 1 and 3 represent 3D frameworks, and POMs as the guest molecules are incorporated into the cages which are composed of the ligands and metals, while compounds 2 and 4 show 3D frameworks by hydrogen bonds. This compounds provide new examples of host–guest compounds based on flexible bis(imidazole) ligands. In addition, the electrochemical property and the catalytic property of compound 1 have also been investigated. - Graphical abstract: Four inorganic–organic hybrid compounds based polyoxometalates (POMs) and flexible ligands, namely, have been obtained under hydrothermal conditions and characterized by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, and thermogravimetric (TG) analyses. Compounds 1–3 are new examples of host–guest compounds based on flexible bis(imidazole) ligands and POMs as the guest molecules are incorporated into the cages which are composed of the ligands and metals. - Highlights: • Polyoxometalate–templated metal–organic frameworks have been prepared. • POMs as the guest molecules are incorporated into the cages. • The cages are flexibility based on flexible bis(imidazole) ligands.« less

Tuning the Luminescence Properties of Colloidal I-III-VI Semiconductor Nanocrystals for Optoelectronics and Biotechnology Applications.

PubMed

Zhong, Haizheng; Bai, Zelong; Zou, Bingsuo

2012-11-01

In the past 5 years, colloidal I-III-VI nanocrystals such as CuInS2, CuInSe2, and AgInS2 have been intensively investigated for the potential to replace commonly available colloidal nanocrystals containing toxic elements in light-emitting and solar-harvesting applications. Many researchers from different disciplines are working on developing new synthetic protocols, performing spectroscopic studies to understand the luminescence mechanisms, and exploring various applications. To achieve enhanced performance, it is very desirable to obtain high-quality materials with tunable luminescence properties. In this Perspective, we highlight the current progress on tuning the luminescence properties of I-III-VI nanocrystals, especially focusing on the advances in the synthesis, spectroscopic properties, as well as the primary applications in light-emitting devices and bioimaging techniques. Finally, we outline the challenges concerning luminescent I-III-VI NCs and list a few important research tasks in this field.

A fast numerical method for the valuation of American lookback put options

NASA Astrophysics Data System (ADS)

Song, Haiming; Zhang, Qi; Zhang, Ran

2015-10-01

A fast and efficient numerical method is proposed and analyzed for the valuation of American lookback options. American lookback option pricing problem is essentially a two-dimensional unbounded nonlinear parabolic problem. We reformulate it into a two-dimensional parabolic linear complementary problem (LCP) on an unbounded domain. The numeraire transformation and domain truncation technique are employed to convert the two-dimensional unbounded LCP into a one-dimensional bounded one. Furthermore, the variational inequality (VI) form corresponding to the one-dimensional bounded LCP is obtained skillfully by some discussions. The resulting bounded VI is discretized by a finite element method. Meanwhile, the stability of the semi-discrete solution and the symmetric positive definiteness of the full-discrete matrix are established for the bounded VI. The discretized VI related to options is solved by a projection and contraction method. Numerical experiments are conducted to test the performance of the proposed method.

Phytoaccumulation of trace elements by wetland plants. 2: Water hyacinth

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

Zhu, Y.L.; Zayed, A.M.; Qian, J.H.

Wetland plants are being used successfully for the phytoremediation of trace elements in natural and constructed wetlands. This study demonstrates the potential of water hyacinth (Eichhornia crassipes), an aquatic floating plant, for the phytoremediation of six trace elements. The ability of water hyacinth to take up and translocate six trace elements--As(V), Cd(II), Cr(VI), Cu(II), Ni(II), and Se(VI)--was studied under controlled conditions. Water hyacinth accumulated Cd and Cr best, Se and Cu at moderate levels, and was a poor accumulator of As and Ni. The highest levels of Cd found in shoots and roots were 371 and 6103 mg kg[sup [minus]1]more » dry wt., respectively, and those of Cr were 119 and 32951 mg kg[sup [minus]1] dry wt, respectively. Cadmium, Cr, Cu, Ni, and As were more highly accumulated in roots than in shoots. In contrast, Se was accumulated more in shoots than in roots at most external concentrations. Water hyacinth had high trace element bioconcentration factors when supplied with low external concentrations of all six elements, particularly Cd, Cr, and Cu. Therefore, water hyacinth will be very efficient at phytoextracting trace elements from wastewater containing low concentrations of these elements. The authors conclude that water hyacinth is a promising candidate for phytoremediation of wastewater polluted with Cd, Cr, Cu, and Se.« less

15 CFR 740.15 - Aircraft and vessels (AVS).

Code of Federal Regulations, 2011 CFR

2011-01-01

... transfer of technology. No technology is transferred to a national of a destination in Country Group E:1... destination in Country Group E:1 (see supplement No. 1 to this part); (vi) Technology is not transferred to a... destination in Country Group E:1 (see supplement No. 1 to this part); (vi) Technology is not transferred to a...

Mobilization of Cr(VI) from chromite ore processing residue through acid treatment.

PubMed

Tinjum, James M; Benson, Craig H; Edil, Tuncer B

2008-02-25

Batch leaching studies on chromite ore processing residue (COPR) were performed using acids to investigate leaching of hexavalent chromium, Cr(VI), with respect to particle size, reaction time, and type of acid (HNO(3) and H(2)SO(4)). Aqueous Cr(VI) is maximized at approximately 0.04 mol Cr(VI) per kg of dry COPR at pH 7.6-8.1. Cr(VI) mobilized more slowly for larger particles, and the pH increased with time and increased more rapidly for smaller particles, suggesting that rate limitations occur in the solid phase. With H(2)SO(4), the pH stabilized at a higher value (8.8 for H(2)SO(4) vs. 8.0 for HNO(3)) and more rapidly (16 h vs. 30 h), and the differences in pH for different particle sizes were smaller. The acid neutralization capacity (ANC) of COPR is very large (8 mol HNO(3) per kg of dry COPR for a stable eluate pH of 7.5). Changes to the elemental and mineralogical composition and distribution in COPR particles after mixing with acid indicate that Cr(VI)-bearing solids dissolved. However, concentrations of Cr(VI) >2800 mg kg(-1) (>50% of the pre-treatment concentration) were still found after mixing with acid, regardless of the particle size, reaction time, or type of acid used. The residual Cr(VI) appears to be partially associated with poorly-ordered Fe and Al oxyhydroxides that precipitated in the interstitial areas of COPR particles. Remediation strategies that use HNO(3) or H(2)SO(4) to neutralize COPR or to maximize Cr(VI) in solution are likely to require extensive amounts of acid, may not mobilize all of the Cr(VI), and may require extended contact time, even under well-mixed conditions.

Dynamic Succession of Groundwater Functional Microbial Communities in Response to Emulsified Vegetable Oil Amendment during Sustained In Situ U(VI) Reduction.

PubMed

Zhang, Ping; Wu, Wei-Min; Van Nostrand, Joy D; Deng, Ye; He, Zhili; Gihring, Thomas; Zhang, Gengxin; Schadt, Chris W; Watson, David; Jardine, Phil; Criddle, Craig S; Brooks, Scott; Marsh, Terence L; Tiedje, James M; Arkin, Adam P; Zhou, Jizhong

2015-06-15

A pilot-scale field experiment demonstrated that a one-time amendment of emulsified vegetable oil (EVO) reduced groundwater U(VI) concentrations for 1 year in a fast-flowing aquifer. However, little is known about how EVO amendment stimulates the functional gene composition, structure, and dynamics of groundwater microbial communities toward prolonged U(VI) reduction. In this study, we hypothesized that EVO amendment would shift the functional gene composition and structure of groundwater microbial communities and stimulate key functional genes/groups involved in EVO biodegradation and reduction of electron acceptors in the aquifer. To test these hypotheses, groundwater microbial communities after EVO amendment were analyzed using a comprehensive functional gene microarray. Our results showed that EVO amendment stimulated sequential shifts in the functional composition and structure of groundwater microbial communities. Particularly, the relative abundance of key functional genes/groups involved in EVO biodegradation and the reduction of NO3 (-), Mn(IV), Fe(III), U(VI), and SO4 (2-) significantly increased, especially during the active U(VI) reduction period. The relative abundance for some of these key functional genes/groups remained elevated over 9 months. Montel tests suggested that the dynamics in the abundance, composition, and structure of these key functional genes/groups were significantly correlated with groundwater concentrations of acetate, NO3 (-), Mn(II), Fe(II), U(VI), and SO4 (2-). Our results suggest that EVO amendment stimulated dynamic succession of key functional microbial communities. This study improves our understanding of the composition, structure, and function changes needed for groundwater microbial communities to sustain a long-term U(VI) reduction. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Dynamic Succession of Groundwater Functional Microbial Communities in Response to Emulsified Vegetable Oil Amendment during Sustained In Situ U(VI) Reduction

PubMed Central

Zhang, Ping; Wu, Wei-Min; Van Nostrand, Joy D.; Deng, Ye; He, Zhili; Gihring, Thomas; Zhang, Gengxin; Schadt, Chris W.; Watson, David; Jardine, Phil; Criddle, Craig S.; Brooks, Scott; Marsh, Terence L.; Tiedje, James M.; Arkin, Adam P.

2015-01-01

A pilot-scale field experiment demonstrated that a one-time amendment of emulsified vegetable oil (EVO) reduced groundwater U(VI) concentrations for 1 year in a fast-flowing aquifer. However, little is known about how EVO amendment stimulates the functional gene composition, structure, and dynamics of groundwater microbial communities toward prolonged U(VI) reduction. In this study, we hypothesized that EVO amendment would shift the functional gene composition and structure of groundwater microbial communities and stimulate key functional genes/groups involved in EVO biodegradation and reduction of electron acceptors in the aquifer. To test these hypotheses, groundwater microbial communities after EVO amendment were analyzed using a comprehensive functional gene microarray. Our results showed that EVO amendment stimulated sequential shifts in the functional composition and structure of groundwater microbial communities. Particularly, the relative abundance of key functional genes/groups involved in EVO biodegradation and the reduction of NO3−, Mn(IV), Fe(III), U(VI), and SO42− significantly increased, especially during the active U(VI) reduction period. The relative abundance for some of these key functional genes/groups remained elevated over 9 months. Montel tests suggested that the dynamics in the abundance, composition, and structure of these key functional genes/groups were significantly correlated with groundwater concentrations of acetate, NO3−, Mn(II), Fe(II), U(VI), and SO42−. Our results suggest that EVO amendment stimulated dynamic succession of key functional microbial communities. This study improves our understanding of the composition, structure, and function changes needed for groundwater microbial communities to sustain a long-term U(VI) reduction. PMID:25862231

Dynamic Succession of Groundwater Functional Microbial Communities in Response to Emulsified Vegetable Oil Amendment during Sustained In Situ U(VI) Reduction

DOE PAGES

Zhang, Ping; Wu, Wei-Min; Van Nostrand, Joy D.; ...

2015-04-10

A pilot-scale field experiment demonstrated that a one-time amendment of emulsified vegetable oil (EVO) reduced groundwater U(VI) concentrations for 1 year in a fast-flowing aquifer. However, little is known about how EVO amendment stimulates the functional gene composition, structure, and dynamics of groundwater microbial communities toward prolonged U(VI) reduction. In this paper, we hypothesized that EVO amendment would shift the functional gene composition and structure of groundwater microbial communities and stimulate key functional genes/groups involved in EVO biodegradation and reduction of electron acceptors in the aquifer. To test these hypotheses, groundwater microbial communities after EVO amendment were analyzed using amore » comprehensive functional gene microarray. Our results showed that EVO amendment stimulated sequential shifts in the functional composition and structure of groundwater microbial communities. Particularly, the relative abundance of key functional genes/groups involved in EVO biodegradation and the reduction of NO 3 -, Mn(IV), Fe(III), U(VI), and SO 4 2- significantly increased, especially during the active U(VI) reduction period. The relative abundance for some of these key functional genes/groups remained elevated over 9 months. Montel tests suggested that the dynamics in the abundance, composition, and structure of these key functional genes/groups were significantly correlated with groundwater concentrations of acetate, NO 3 -, Mn(II), Fe(II), U(VI), and SO 4 2-. Our results suggest that EVO amendment stimulated dynamic succession of key functional microbial communities. Finally, this study improves our understanding of the composition, structure, and function changes needed for groundwater microbial communities to sustain a long-term U(VI) reduction.« less

Dynamic Succession of Groundwater Functional Microbial Communities in Response to Emulsified Vegetable Oil Amendment during Sustained In Situ U(VI) Reduction

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

Zhang, Ping; Wu, Wei-Min; Van Nostrand, Joy D.

A pilot-scale field experiment demonstrated that a one-time amendment of emulsified vegetable oil (EVO) reduced groundwater U(VI) concentrations for 1 year in a fast-flowing aquifer. However, little is known about how EVO amendment stimulates the functional gene composition, structure, and dynamics of groundwater microbial communities toward prolonged U(VI) reduction. In this paper, we hypothesized that EVO amendment would shift the functional gene composition and structure of groundwater microbial communities and stimulate key functional genes/groups involved in EVO biodegradation and reduction of electron acceptors in the aquifer. To test these hypotheses, groundwater microbial communities after EVO amendment were analyzed using amore » comprehensive functional gene microarray. Our results showed that EVO amendment stimulated sequential shifts in the functional composition and structure of groundwater microbial communities. Particularly, the relative abundance of key functional genes/groups involved in EVO biodegradation and the reduction of NO 3 -, Mn(IV), Fe(III), U(VI), and SO 4 2- significantly increased, especially during the active U(VI) reduction period. The relative abundance for some of these key functional genes/groups remained elevated over 9 months. Montel tests suggested that the dynamics in the abundance, composition, and structure of these key functional genes/groups were significantly correlated with groundwater concentrations of acetate, NO 3 -, Mn(II), Fe(II), U(VI), and SO 4 2-. Our results suggest that EVO amendment stimulated dynamic succession of key functional microbial communities. Finally, this study improves our understanding of the composition, structure, and function changes needed for groundwater microbial communities to sustain a long-term U(VI) reduction.« less

Polymer complexes. LVII. Supramolecular assemblies of novel polymer complexes of dioxouranium(VI) with some substituted allyl azo dye compounds

NASA Astrophysics Data System (ADS)

Diab, M. A.; El-Sonbati, A. Z.; El-Bindary, A. A.; Balboula, M. Z.

2013-05-01

A novel method to synthesize some dioxouranium(VI) polymer complexes of the general formula [UO2(Ln)2(OAc)2] (where HLn = azo allyl rhodanine). The structure of the novel mononuclear dioxoutranium(VI) polymer complexes was characterized using elemental analysis, spectral (electronic, infrared, 1H &13C NMR) studies, magnetic susceptibility measurements and thermal analysis. The molar conductivities show that all the polymer complexes are non-electrolytes. The IR showed that the ligand HLn act as bidentate neutral through carbonyl group and imine group nitrogen atom forming thereby a six-membered chelating ring and concomitant formation of an intramolecular hydrogen bond. The υ3 frequency of UO2+2 has been shown to be an excellent molecular probe for studying the coordinating power of the ligands. The values of υ3 of the prepared complexes containing UO2+2 were successfully used to calculate the force constant, FUO (10-8 N/Å) and the bond length RUO (Å) of the Usbnd O bond. A strategy based upon both theoretical and experimental investigations has been adopted. The theoretical aspects are described in terms of the well-known theory of 5d-4f transitions. Wilson's, matrix method, Badger's formula, and Jones and El-Sonbati equations were used to calculate the Usbnd O bond distances from the values of the stretching and interaction force constants. The most probable correlation between Usbnd O force constant to Usbnd O bond distance were satisfactorily discussed in term of Badger's rule and the equations suggested by Jones and El-Sonbati. The effect of Hammet constant is also discussed.

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

PubMed

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

2016-07-01

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

Rare-earth element fractionation in uranium ore and its U(VI) alteration minerals

DOE PAGES

Balboni, Enrica; Spano, T; Cook, N; ...

2017-10-20

We developed a cation exchange chromatography method employing sulfonated polysterene cation resin (DOWEX AG50-X8) in order to separate rare-earth elements (REEs) from uranium-rich materials. The chemical separation scheme is designed to reduce matrix effects and consequently yield enhanced ionization efficiencies for concentration determinations of REEs without significant fractionation using solution mode-inductively coupled plasma mass spectrometry (ICP-MS) analysis. This method was then applied to determine REE abundances in four uraninite (ideally UO 2) samples and their associated U(VI) alteration minerals. In three of the samples analyzed, the concentration of REEs for primary uraninite are higher than those for their corresponding secondarymore » uranium alteration phases. The results for U(VI) alteration minerals of two samples indicate enrichment of the light REEs (LREEs) over the heavy REEs (HREEs). This differential mobilization is attributed to differences in the mineralogical composition of the U(VI) alteration. There is a lack of fractionation of the LREEs in the uraninite alteration rind that is composed of U(VI) minerals containing Ca 2+ as the interlayer cation (uranophane and bequerelite); contrarily, U(VI) alteration minerals containing K + and Pb 2+ as interlayer cations (fourmarierite, dumontite) indicate fractionation (enrichment) of the LREEs. Our results have implications for nuclear forensic analyses since a comparison is reported between the REE abundances for the CUP-2 (processed uranium ore) certified reference material and previously determined values for uranium ore concentrate (UOC) produced from the same U deposit (Blind River/Elliott Lake, Canada). UOCs represent the most common form of interdicted nuclear material and consequently is material frequently targeted for forensic analysis. The comparison reveals similar chondrite normalized REE signatures but variable absolute abundances. Based on the results reported here, the latter may be attributed to the differing REE abundances between primary ore and associated alteration phases, and/or is related to varying fabrication processes adopted during production of UOC.« less

Rare-earth element fractionation in uranium ore and its U(VI) alteration minerals

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

Balboni, Enrica; Spano, T; Cook, N

We developed a cation exchange chromatography method employing sulfonated polysterene cation resin (DOWEX AG50-X8) in order to separate rare-earth elements (REEs) from uranium-rich materials. The chemical separation scheme is designed to reduce matrix effects and consequently yield enhanced ionization efficiencies for concentration determinations of REEs without significant fractionation using solution mode-inductively coupled plasma mass spectrometry (ICP-MS) analysis. This method was then applied to determine REE abundances in four uraninite (ideally UO 2) samples and their associated U(VI) alteration minerals. In three of the samples analyzed, the concentration of REEs for primary uraninite are higher than those for their corresponding secondarymore » uranium alteration phases. The results for U(VI) alteration minerals of two samples indicate enrichment of the light REEs (LREEs) over the heavy REEs (HREEs). This differential mobilization is attributed to differences in the mineralogical composition of the U(VI) alteration. There is a lack of fractionation of the LREEs in the uraninite alteration rind that is composed of U(VI) minerals containing Ca 2+ as the interlayer cation (uranophane and bequerelite); contrarily, U(VI) alteration minerals containing K + and Pb 2+ as interlayer cations (fourmarierite, dumontite) indicate fractionation (enrichment) of the LREEs. Our results have implications for nuclear forensic analyses since a comparison is reported between the REE abundances for the CUP-2 (processed uranium ore) certified reference material and previously determined values for uranium ore concentrate (UOC) produced from the same U deposit (Blind River/Elliott Lake, Canada). UOCs represent the most common form of interdicted nuclear material and consequently is material frequently targeted for forensic analysis. The comparison reveals similar chondrite normalized REE signatures but variable absolute abundances. Based on the results reported here, the latter may be attributed to the differing REE abundances between primary ore and associated alteration phases, and/or is related to varying fabrication processes adopted during production of UOC.« less

Interplay of sugar, light and gibberellins in expression of Rosa hybrida vacuolar invertase 1 regulation.

PubMed

Rabot, Amélie; Portemer, Virginie; Péron, Thomas; Mortreau, Eric; Leduc, Nathalie; Hamama, Latifa; Coutos-Thévenot, Pierre; Atanassova, Rossitza; Sakr, Soulaiman; Le Gourrierec, José

2014-10-01

Our previous findings showed that the expression of the Rosa hybrida vacuolar invertase 1 gene (RhVI1) was tightly correlated with the ability of buds to grow out and was under sugar, gibberellin and light control. Here, we aimed to provide an insight into the mechanistic basis of this regulation. In situ hybridization showed that RhVI1 expression was localized in epidermal cells of young leaves of bursting buds. We then isolated a 895 bp fragment of the promoter of RhVI1. In silico analysis identified putative cis-elements involved in the response to sugars, light and gibberellins on its proximal part (595 bp). To carry out functional analysis of the RhVI1 promoter in a homologous system, we developed a direct method for stable transformation of rose cells. 5' deletions of the proximal promoter fused to the uidA reporter gene were inserted into the rose cell genome to study the cell's response to exogenous and endogenous stimuli. Deletion analysis revealed that the 468 bp promoter fragment is sufficient to trigger reporter gene activity in response to light, sugars and gibberellins. This region confers sucrose- and fructose-, but not glucose-, responsive activation in the dark. Inversely, the -595 to -468 bp region that carries the sugar-repressive element (SRE) is required to down-regulate the RhVI1 promoter in response to sucrose and fructose in the dark. We also demonstrate that sugar/light and gibberellin/light act synergistically to up-regulate β-glucuronidase (GUS) activity sharply under the control of the 595 bp pRhVI1 region. These results reveal that the 127 bp promoter fragment located between -595 and -468 bp is critical for light and sugar and light and gibberellins to act synergistically. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

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

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

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

Complexation of Eu(III), Pb(II), and U(VI) with a Paramecium glycoprotein: Microbial transformation of heavy elements in the aquatic environment.

PubMed

Kozai, Naofumi; Sakamoto, Fuminori; Tanaka, Kazuya; Ohnuki, Toshihiko; Satoh, Takahiro; Kamiya, Tomihiro; Grambow, Bernd

2018-04-01

This study investigated the interaction of inorganic aqueous Eu(III), Pb(II), and U(VI) with Paramecium sp., a representative single-celled protozoan that lives in freshwater. Living and prekilled Paramecium cells were tested. The prekilled cells were killed with a fixative. After 24 h exposure of the cells to inorganic aqueous solutions containing Eu(III) or U(VI), analyses by microparticle-induced X-ray emission with a focused beam (<1 μm) did not detect Eu and U in the living cells, whereas Eu and U were detected in the prekilled cells. Size exclusion chromatography coupled with on-line ultraviolet-visible detection and elemental detection by inductively coupled plasma mass spectrometry of the aqueous phases collected after the living cell experiments revealed that a fraction of the Eu, Pb, and U in the aqueous phase bound to a large (ca. 250 kDa) Paramecium biomolecule and formed a metal-organic complex. The characteristics of the biomolecule were consistent with those of the soluble glycoproteins covering the surfaces of Paramecium cells. These results show that Paramecium cells transform inorganic aqueous Eu, Pb, and U to organic complexes. This paper discusses the relation between this novel complexation and the sorption of these heavy elements on Paramecium cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

Selenium Administration Alleviates Toxicity of Chromium(VI) in the Chicken Brain.

PubMed

Hao, Pan; Zhu, Yiran; Wang, Shenghua; Wan, Huiyu; Chen, Peng; Wang, Yang; Cheng, Ziqiang; Liu, Yongxia; Liu, Jianzhu

2017-07-01

Selenium (Se) can play a protective role against heavy metal toxicity. This experiment aims to evaluate the effect of Se supplementation at different doses on the chicken brains. Oxidative stress was induced in the chicken brains by chromium(VI). A total of 105 Hyland brown male chickens were randomly divided into seven groups, including the control group, poisoned group [6%LD 50 K 2 Cr 2 O 7 body weight (B.W.)], and detoxification groups K 2 Cr 2 O 7 (6%LD 50 ) + Se (0.31, 0.63, 1.25, 2.50, and 5.00 Na 2 SeO 3 mg/kg B.W.) orally in water for 42 days. The chickens were detected by the activities of mitochondrial membrane potential, 2'-benzoyloxycinnamaldehyde, superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), and Ca 2+ -ATPase. Cr(VI) administration caused histopathological damage. In addition, changes in oxidative stress indicators were observed in the chicken's brains. Se supplement increased the levels of GSH, mitochondrial membrane potential (MMP), and Ca 2+ -ATPase and reduced MDA activity in the detoxification groups. However, the high-dose Se supplementation groups of 2.50 and 5.00 mg/kg reduced the activities of GSH, MMP, and Ca 2+ -ATPase; increased the brain-body ratio; and increased SOD activity. In conclusion, Cr(VI) exposure caused oxidative stress. Se exerted a remission effect on toxic responses in the chicken brains. However, a high Se concentration was synergistic to the toxic effect of Cr(VI).

Residual Gas in Closed Systems. III: Development and Reduction of Gases Generated by Source Materials

NASA Technical Reports Server (NTRS)

Palosz, W.

2003-01-01

The amounts and composition of residual gases formed in sealed ampoules loaded with different sources (elements and II-VI and IV-VI compounds) after consecutive annealings were investigated. A given source was subjected to a series of heat treatments, with intermediate measurements and removal of the gas accumulated in the system. The results of these experiments are discussed in terms of the underlying thermochemical and kinetic phenomena and practical limitations of reducing the amount of residual gases in sealed ampoules.

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

PubMed

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 confirmed the involvement of the carbonyl groups (C==O) and the methoxy groups (OCH3) in the mechanism of chromium adsorption. Thermodynamic study, such as enthalpy (ΔH), free energy (ΔG) and entropy change (ΔS) indicated that the overall adsorption process was endothermic, spontaneous and randomness. In addition, the adsorption process was favored at high temperatures. Copyright © 2012 Elsevier Ltd. All rights reserved.

An evaluation of the protective role of α-tocopherol on free radical induced hepatotoxicity and nephrotoxicity due to chromium in rats

PubMed Central

Balakrishnan, Rajendran; Satish Kumar, Chitturi Sree; Rani, Matukumalli Usha; Srikanth, Mylaram Kistaiah; Boobalan, Gopu; Reddy, Alla Gopala

2013-01-01

Aim: To avert the health problems induced by many environmental pollutants, available antioxidants have been evaluated. The present study was aimed to investigate whether α-tocopherol could protect the hexavalent chromium (Cr VI)-induced peroxidation in the liver and kidney and to explore the underlying mechanism of the same. Materials and Methods: A total of 24 Wistar adult female rats were equally divided into four groups. Group 1 served as control while Groups 2 and 3 were administered K2Cr2O7(10 mg/kg b.wt. s.c. single dose). In addition to (Cr VI), Group 3 also received α-tocopherol (125 mg/kg, daily) by oral gavage for 14 days. Group 4 was maintained as α-tocopherol control (dose as above). At the end of 14 days, blood samples were drawn for hematology. Subsequently, all the rats were sacrificed to collect liver and kidney samples for assay of tissue peroxidation markers, antioxidant markers and functional markers and histopathology. Results: Administration of chromium (Cr VI) in Group 2 significantly (P < 0.05) reduced the antioxidant markers such as superoxide dismutase and reduced glutathione along with significant (P < 0.05) increase in peroxidation markers such as malondialdehyde and protein carbonyls in the liver and kidney as compared with other groups. The functional markers in serum such as total protein was decreased significantly (P < 0.05), whereas other functional markers viz. alanine transaminase, blood urea nitrogen and creatinine were increased significantly (P < 0.05) in Group 2 as compared with the other groups. Significant (P < 0.05) decrease in hemoglobin, packed cell volume, total erythrocyte count, mean corpuscular volume, mean corpuscular hemoglobin and total leukocyte count were observed in Cr VI treated Group 2 rats. Prominent pathological changes were observed in the liver and kidney of Group 2. Co-treatment with α-tocopherol in Group 3 rats significantly (P < 0.05) reversed the Cr VI induced changes. The parameters in the study in Group 4 did not differ as compared with Group 1. Conclusions: α–tocopherol exhibited protective effect against Cr VI-induced damage to the liver and kidney by inhibition of lipid peroxidation owing its antioxidant activity. PMID:24130385

Testing a Model of Diabetes Self-Care Management: A Causal Model Analysis with LISREL.

ERIC Educational Resources Information Center

Nowacek, George A.; And Others

1990-01-01

A diabetes-management model is presented, which includes an attitudinal element and depicts relationships among causal elements. LISREL-VI was used to analyze data from 115 Type-I and 105 Type-II patients. The data did not closely fit the model. Results support the importance of the personal meaning of diabetes. (TJH)

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

PubMed

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.

Environmental Presence of Hexavalent but Not Trivalent Chromium Causes Neurotoxicity in Exposed Drosophila melanogaster.

PubMed

Singh, Pallavi; Chowdhuri, D Kar

2017-07-01

A number of environmental chemicals are known to cause neurotoxicity to exposed organisms. Chromium (Cr), one of the major elements in earth's crust, is a priority environmental chemical depending on its valence state, and limited information is available on its neurotoxic potential. We, therefore, explored the neurotoxic potential of environmentally present trivalent- (Cr(III)) and hexavalent-Cr (Cr(VI)) on tested brain cell types in a genetically tractable organism Drosophila melanogaster along with its organismal response. Third instar larvae of w 1118 were fed environmentally relevant concentrations (5.0-20.0 μg/ml) of Cr(III)- or Cr(VI)-salt-mixed food for 24 and 48 h, and their exposure effects were examined in different brain cells of exposed organism. A significant reduction in the number of neuronal cells was observed in organism that were fed Cr(VI)- but not Cr(III)-salt-mixed food. Interestingly, glial cells were not affected by Cr(III) or Cr(VI) exposure. The tested cholinergic and dopaminergic neuronal cells were affected by Cr(VI) only with the later by 20.0 μg/ml Cr(VI) exposure after 48 h. The locomotor activity was significantly affected by Cr(VI) in exposed organism. Concomitantly, a significant increase in the level of reactive oxygen species (ROS) coupled with increased oxidative stress led to apoptotic cell death in the tested brain cells of Cr(VI)-exposed Drosophila, which were reversed by vitamin C supplementation. Conclusively, the present study provides evidence of environmental Cr(VI)-induced adversities on the brain of exposed Drosophila along with behavioral deficit which would likely to have relevance in humans and recommends Drosophila as a model for neurotoxicity.

Four-year antibody persistence and response to a booster dose of a pentavalent MenABCWY vaccine administered to healthy adolescents and young adults

PubMed Central

Sáez-Llorens, Xavier; Beltran-Rodriguez, Johnny; Novoa Pizarro, Jose M.; Mensi, Ilhem; Keshavan, Pavitra; Toneatto, Daniela

2018-01-01

ABSTRACT This open-label, multicenter extension study (NCT02451514) assessed persistence of Neisseria meningitidis serogroups ABCWY antibodies 4 years after primary vaccination. Adolescents and young adults who previously received 2 doses of MenABCWY+OMV (Group III), 1 dose of MenACWY-CRM (Group VI), or newly-recruited vaccine-naïve participants (Group VII) were administered 1 (Group III) or 2 doses (Groups VI and VII) of MenABCWY+OMV, 1 month apart. Immunogenicity was assessed by human serum bactericidal assay (hSBA). Safety and reactogenicity were also evaluated. Percentages of participants with hSBA titers ≥8 (serogroups ACWY), ≥5 (serogroup B) and hSBA geometric mean titers (GMTs) were evaluated in all 129 enrolled participants (Group III: 33; Group VI: 46; Group VII: 50). Anti-ACWY antibody concentrations waned over 4 years post-vaccination, but remained above pre-vaccination concentrations. Similarly, levels of antibodies against serogroup B test strains also waned over 4 years post-vaccination, but remained above pre-vaccination concentrations for some strains. MenABCWY+OMV booster induced a robust anamnestic anti-ACWY response in Group III and VI and a good response against serogroup B test strains (≥82%) in Group III. In serogroup B-naïve participants (Groups VI and VII), anti-B responses to 2 doses of MenABCWY+OMV were less homogenous and lower than in Group III. MenABCWY+OMV was reactogenic, but well-tolerated. No safety concerns were identified. These findings indicate that although antibodies against N. meningitidis serogroups ABCWY waned over 4 years post-vaccination, exposure to a MenABCWY+OMV booster dose elicits an anamnestic response in adolescents previously exposed to the same or another multivalent meningococcal vaccine. PMID:29601256

Vibration control of a cluster of buildings through the Vibrating Barrier

NASA Astrophysics Data System (ADS)

Tombari, A.; Garcia Espinosa, M.; Alexander, N. A.; Cacciola, P.

2018-02-01

A novel device, called Vibrating Barrier (ViBa), that aims to reduce the vibrations of adjacent structures subjected to ground motion waves has been recently proposed. The ViBa is a structure buried in the soil and detached from surrounding buildings that is able to absorb a significant portion of the dynamic energy arising from the ground motion. The working principle exploits the dynamic interaction among vibrating structures due to the propagation of waves through the soil, namely the structure-soil-structure interaction. In this paper the efficiency of the ViBa is investigated to control the vibrations of a cluster of buildings. To this aim, a discrete model of structures-site interaction involving multiple buildings and the ViBa is developed where the effects of the soil on the structures, i.e. the soil-structure interaction (SSI), the structure-soil-structure interaction (SSSI) as well as the ViBa-soil-structures interaction are taken into account by means of linear elastic springs. Closed-form solutions are derived to design the ViBa in the case of harmonic excitation from the analysis of the discrete model. Advanced finite element numerical simulations are performed in order to assess the efficiency of the ViBa for protecting more than a single building. Parametric studies are also conducted to identify beneficial/adverse effects in the use of the proposed vibration control strategy to protect cluster of buildings. Finally, experimental shake table tests are performed to a prototype of a cluster of two buildings protected by the ViBa device for validating the proposed numerical models.

Simultaneous Speciation Analysis of Arsenic, Chromium, and Selenium in the Bioaccessible Fraction for Realistic Risk Assessment of Food Safety.

PubMed

Sadiq, Nausheen W; Beauchemin, Diane

2017-12-19

A simple and fast method was developed for risk assessment of As, Cr, and Se in food, which is demonstrated here using three cooked and uncooked rice samples (basmati as well as organic white and brown rice). The bioaccessible fraction was first determined through online leaching of rice minicolumns (maintained at 37 °C) sequentially with artificial saliva, gastric juice, and intestinal juice while continuously monitoring potentially toxic elements (As, Cr, and Se) by inductively coupled plasma mass spectrometry (ICPMS). Then, a new ion chromatography method with online detection by ICPMS was developed for the simultaneous speciation analysis of As, Cr, and Se in the bioaccessible fraction to determine the portion of these elements that was actually toxic. Using gradient elution, four As species [As(III), As(V), monomethylarsonic acid, and dimethylarsinic acid], two Cr species [Cr(III) and Cr(VI)], and two Se species [Se(IV) and Se(VI)] were separated within 12 min. The simultaneous speciation analysis of As, Cr, and Se revealed that the simple act of cooking can convert all of the carcinogenic Cr(VI) to the safer Cr(III).

The Spread of Metals into the Low-redshift Intergalactic Medium

NASA Astrophysics Data System (ADS)

Pratt, Cameron T.; Stocke, John T.; Keeney, Brian A.; Danforth, Charles W.

2018-03-01

We investigate the association between galaxies and metal-enriched and metal-deficient absorbers in the local universe (z < 0.16) using a large compilation of far-ultraviolet spectra of bright active galactic nuclei targets observed with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope. In this homogeneous sample of 18 O VI detections at {N}{{O}{{VI}}}≥slant 13.5 {cm}}-2 and 18 nondetections at {N}{{O}{{VI}}}< 13.5 {cm}}-2 using {Ly}α absorbers with {N}{{H}{{I}}}≥slant {10}14 {cm}}-2, the maximum distance O VI extends from galaxies of various luminosities is ∼0.6 Mpc, or ∼5 virial radii, confirming and refining earlier results. This is an important value that must be matched by numerical simulations, which input the strength of galactic winds at the sub-grid level. We present evidence that the primary contributors to the spread of metals into the circum- and intergalactic media are sub-L* galaxies (0.25{L}* < L< {L}* ). The maximum distances that metals are transported from these galaxies is comparable to, or less than, the size of a group of galaxies. These results suggest that, where groups are present, the metals produced by the group galaxies do not leave the group. Since many O VI nondetections in our sample occur at comparably close impact parameters as those of the metal-bearing absorbers, some more pristine intergalactic material appears to be accreting onto groups where it can mix with metal-bearing clouds.

Trace-metal concentrations in African dust: effects of long-distance transport and implications for human health

USGS Publications Warehouse

Garrison, Virginia; Lamothe, Paul; Morman, Suzette; Plumlee, Geoffrey S.; Gilkes, Robert; Prakongkep, Nattaporn

2010-01-01

The Sahara and Sahel lose billions of tons of eroded mineral soils annually to the Americas and Caribbean, Europe and Asia via atmospheric transport. African dust was collected from a dust source region (Mali, West Africa) and from downwind sites in the Caribbean [Trinidad-Tobago (TT) and U.S. Virgin Islands (VI)] and analysed for 32 trace-elements. Elemental composition of African dust samples was similar to that of average upper continental crust (UCC), with some enrichment or depletion of specific trace-elements. Pb enrichment was observed only in dust and dry deposition samples from the source region and was most likely from local use of leaded gasoline. Dust particles transported long-distances (VI and TT) exhibited increased enrichment of Mo and minor depletion of other elements relative to source region samples. This suggests that processes occurring during long-distance transport of dust produce enrichment/depletion of specific elements. Bioaccessibility of trace-metals in samples was tested in simulated human fluids (gastric and lung) and was found to be greater in downwind than source region samples, for some metals (e.g., As). The large surface to volume ratio of the dust particles (<2.5 µm) at downwind sites may be a factor.

Efficacy and safety of vi-tetanus toxoid conjugated typhoid vaccine (PedaTyph™) in Indian children: School based cluster randomized study.

PubMed

Mitra, Monjori; Shah, Nitin; Ghosh, Apurba; Chatterjee, Suparna; Kaur, Iqbal; Bhattacharya, Nisha; Basu, Suparna

2016-04-02

Vi polysaccharide typhoid vaccines cannot be used in children <2 years owing to poor immunogenic and T cell independent properties. Conjugate vaccine prepared by binding Vi to tetanus toxoids (Vi-TT) induces protective levels even in children <2 years. We evaluated efficacy and safety following vaccination with a Vi-TT vaccine in children 6 months to 12 years of age. Overall, 1765 subjects were recruited from two registered municipal urban slums of southern Kolkata. Most of the children of the slum dwellers attended the schools in the locality which was selected with permission from the school authority. Schools were randomly divided into vaccinated (Test group) and unvaccinated group (Control group). Children and their siblings of test group received 2-doses of PedaTyph™ vaccine at 6 weeks interval. Control group received vaccines as per national guidelines. Adverse events (AEs) were examined after 30 minutes, 1 month and clinical events were observed till 12 months post-vaccination. Incidence of culture positive typhoid fever in the control group was 1.27% vis-a-vis none in vaccine group during 12 months. In subgroup evaluated for immunogenicity, an antibody titer value of 1.8 EU/ml (95% CI: 1.5 EU/ml, 2.2 EU/ml), 32 EU/ml (95% CI: 27.0 EU/ml, 39.0 EU/ml) and 14 EU/ml (95% CI: 12.0 EU/ml, 17.0 EU/ml) at baseline, 6 weeks and 12 months, respectively was observed. Sero-conversion among the sub-group was 100% after 6 weeks of post-vaccination and 83% after 12 months considering 4-fold rise from baseline. The efficacy of vaccine was 100 % (95% CI: 97.6%, 100%) in the first year of follow-up with minimal AEs post vaccination. Vi conjugate typhoid vaccine conferred 100% protection against typhoid fever in 1765 children 6 months to 12 years of age with high immunogenicity in a subgroup from the vaccine arm.

Effect of various selenium doses on chromium(IV)-induced nephrotoxicity in a male chicken model.

PubMed

Wan, Huiyu; Zhu, Yiran; Chen, Peng; Wang, Yang; Hao, Pan; Cheng, Ziqiang; Liu, Yongxia; Liu, Jianzhu

2017-05-01

Our study aimed to explore whether Na 2 SeO 3 (Se) can alleviate the nephrotoxicity induced by K 2 Cr 2 O 7 [Cr(VI)]. One hundred and five male chickens were randomly divided into seven groups with 15 chickens each group: The 6 experimental groups received K 2 Cr 2 O 7 alone or in combination with 0.31, 0.63, 1.25, 2.50, and 5.00 mg/kg for 42 days, respectively, while control group was treated with equivalent water. Exposure to Cr(VI) significantly increased MDA contents and organ coefficient, whereas decreased T-SOD activities, Ca 2+ -ATPase activities, mitochondrial membrane potential and GSH contents, and histological studies demonstrated renal damage. Above indicators were restored by Se supplement (0.31, 0.63, and 1.25 mg/kg), in which supplement with 0.63 mg/kg Se developed more effectively than the other two groups; on the contrary, in the groups of Se supplement with 2.50 and 5.00 mg/kg, the above indicators were not ameliorated and even exacerbated. This study demonstrated that Cr(VI) can result in kidney oxidative damage in male chickens, and Se of certain dose has the protective effects against Cr(VI)-induced nephrptoxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dermoscopic nevus patterns in skin of colour: a prospective, cross-sectional, morphological study in individuals with skin type V and VI.

PubMed

Lallas, A; Reggiani, C; Argenziano, G; Kyrgidis, A; Bakos, R; Masiero, N C M S; Scheibe, A B; Cabo, H; Ozdemir, F; Sortino-Rachou, A M; Turk, B Gerceker; Moscarella, E; Longo, C; Zalaudek, I

2014-11-01

Most of the knowledge on the prevailing dermoscopic patterns of acquired melanocytic nevi (AMV) is based on studies in Caucasians, while little research focuses on the dermoscopic variability in nevi in skin of colour. To analyse the prevalent dermoscopic nevus patterns in subjects with a skin type (ST) V and VI. Prospective, cross-sectional, morphological study was conducted in six clinics with enrolment of consecutive individuals with a ST V or VI. Digital dermoscopic images of selected representative AMN were assessed for dermoscopic colours, morphological patterns and pigment distribution. Analysis of 300 nevi from subjects with ST V and VI revealed significant differences in the nevus pattern between these two groups. The majority of nevi in ST V revealed a reticular pattern, whereas persons with ST VI more frequently exhibited a structureless pattern. Black, blue and grey were more frequent in ST VI, whereas the vast majority of nevi in ST V individuals showed dark brown colour. Our study provides new insights into the nevus pattern in individuals with a dark pigmentary trait, which may aid the diagnosis and management of nevi in this patients group. © 2013 European Academy of Dermatology and Venereology.

Equilibrium and kinetics study on hexavalent chromium adsorption onto diethylene triamine grafted glycidyl methacrylate based copolymers.

PubMed

Maksin, Danijela D; Nastasović, Aleksandra B; Milutinović-Nikolić, Aleksandra D; Suručić, Ljiljana T; Sandić, Zvjezdana P; Hercigonja, Radmila V; Onjia, Antonije E

2012-03-30

Two porous and one non-porous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) [abbreviated PGME] were prepared by suspension copolymerization and functionalized with diethylene triamine [abbreviated PGME-deta]. Samples were characterized by elemental analysis, mercury porosimetry, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Kinetics of Cr(VI) sorption by PGME-deta were investigated in batch static experiments, in the temperature range 25-70°C. Sorption was rapid, with the uptake capacity higher than 80% after 30 min. Sorption behavior and rate-controlling mechanisms were analyzed using five kinetic models (pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion and Bangham model). Kinetic studies showed that Cr(VI) adsorption adhered to the pseudo-second-order model, with definite influence of pore diffusion. Equilibrium data was tested with Langmuir, Freundlich and Tempkin adsorption isotherm models. Langmuir model was the most suitable indicating homogeneous distribution of active sites on PGME-deta and monolayer sorption. The maximum adsorption capacity from the Langmuir model, Q(max), at pH 1.8 and 25°C was 143 mg g(-1) for PGME2-deta (sample with the highest amino group concentration) while at 70°C Q(max) reached the high value of 198 mg g(-1). Thermodynamic parameters revealed spontaneous and endothermic nature of Cr(VI) adsorption onto PGME-deta. Copyright © 2012 Elsevier B.V. All rights reserved.

Clinical and serological responses following primary and booster immunization with Salmonella typhi Vi capsular polysaccharide vaccines.

PubMed

Keitel, W A; Bond, N L; Zahradnik, J M; Cramton, T A; Robbins, J B

1994-01-01

Clinical and serum antibody responses following intramuscular injection of two formulations of Salmonella typhi Vi capsular polysaccharide (Vi) were assessed in a double-blind evaluation. Healthy adults were randomly assigned to receive a 25 micrograms dose of liquid (Vi-Liq; n = 182) or freeze-dried Vi vaccine (Vi-Lyoph; n = 55), or placebo (n = 86). Erythema and/or induration > or = 1 cm in diameter at the injection site developed in 13/182 (7%) of Vi-Liq and 3/55 (5%) of Vi-Lyoph recipients (not significant, n.s.). Fever (oral temperature > or = 100 degrees F (37.8 degrees C)) occurred in < 2% of vaccinees. The frequencies of rises of fourfold or greater and of maximal Vi antibody levels were similar in the two vaccine groups. Fourfold or greater rises in serum Vi antibody levels (RIA) developed in 53% of Vi-Lyoph and 60% of Vi-Liq recipients by 1 week (n.s.), and 98 and 93%, respectively, by 1 month (n.s.). The frequencies of adverse reactions and mean Vi antibody levels following booster immunization with Vi-Liq 27 to 34 months after primary immunization (n = 55) were similar to those observed following primary immunization, although subjects given a booster dose were more likely to develop local reactions > or = 1 cm in diameter than those given a first dose (10/55 versus 13/182, p = 0.013 by the chi 2 test). Primary and booster immunizations with the Vi vaccines are well tolerated in healthy adults; mean Vi antibody levels remain significantly elevated for up to 34 months after primary immunization.

75 FR 41201 - Formations of, Acquisitions by, and Mergers of Bank Holding Companies

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-15

...Gen Capital Group VI LLC, and CapGen Capital Group VI LP, both of New York, New York; to become bank... FEDERAL RESERVE SYSTEM Formations of, Acquisitions by, and Mergers of Bank Holding Companies The companies listed in this notice have applied to the Board for approval, pursuant to the Bank Holding Company...

Chromium sorption and Cr(VI) reduction to Cr(III) by grape stalks and yohimbe bark.

PubMed

Fiol, Núria; Escudero, Carlos; Villaescusa, Isabel

2008-07-01

In this work, two low cost sorbents, grape stalks and yohimbe bark wastes were used to remove Cr(VI) and Cr(III) from aqueous solutions. Batch experiments were designed to obtain Cr(VI) and Cr(III) sorption data. The mechanism of Cr(III) and Cr(VI) removal and Cr(VI) reduction to Cr(III) by the two vegetable wastes, has been investigated. Fourier transform infrared rays (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis on solid phase were performed to determine the main functional groups that might be involved in metal uptake and to confirm the presence of Cr(III) on the sorbent, respectively. Results put into evidence that both sorbents are able to reduce Cr(VI) to its trivalent form.

a New ENDF/B-VII.0 Based Multigroup Cross-Section Library for Reactor Dosimetry

NASA Astrophysics Data System (ADS)

Alpan, F. A.; Anderson, S. L.

2009-08-01

The latest of the ENDF/B libraries, ENDF/B-VII.0 was released in December 2006. In this paper, the ENDF/B-VII.O evaluations were used in generating a new coupled neutron/gamma multigroup library having the same group structure of VITAMIN-B6, i.e., the 199-neutron, 42-gamma group library. The new library was generated utilizing NJOY99.259 for pre-processing and the AMPX modules for post-processing of cross sections. An ENDF/B-VI.3 based VITAMIN-B6-like library was also generated. The fine-group libraries and the ENDF/B-VI.3 based 47-neutron, 20-gamma group BUGLE-96 library were used with the discrete ordinates code DORT to obtain a three-dimensional synthesized flux distribution from r, r-θ, and r-z models for a standard Westinghouse 3-loop design reactor. Reaction rates were calculated for ex-vessel neutron dosimetry containing 63Cu(n,α)60Co, 46Ti(n,p)46Sc, 54Fe(n,P)54Mn, 58Ni(n,P)58Co, 238U(n,f)137Cs, 237Np(n,f)137Cs, and 59Co(n,γ)60Co (bare and cadmium covered) reactions. Results were compared to measurements. In comparing the 199-neutron, 42-gamma group ENDF/B-VI.3 and ENDF/B-VII.O libraries, it was observed that the ENDF/B-VI.3 based library results were in better agreement with measurements. There is a maximum difference of 7% (for the 63Cu(n,α)60Co reaction rate calculation) between ENDF/B-VI.3 and ENDF/B-VII.O. Differences between ENDF/B-VI.3 and ENDF/B-VII.O libraries are due to 16O, 1H, 90Zr, 91Zr, 92Zr, 238U, and 239Pu evaluations. Both ENDF/B-VI.3 and ENDF/B-VII.O library calculated reaction rates are within 20% of measurement and meet the criterion specified in the U. S. Nuclear Regulatory Commission Regulatory Guide 1.190, "Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence."

Effects of low-level laser therapy on stem cells from human exfoliated deciduous teeth

PubMed Central

FERNANDES, Ana Paula; JUNQUEIRA, Marina de Azevedo; MARQUES, Nádia Carolina Teixeira; MACHADO, Maria Aparecida Andrade Moreira; SANTOS, Carlos Ferreira; OLIVEIRA, Thais Marchini; SAKAI, Vivien Thiemy

2016-01-01

ABSTRACT Low-Level Laser Therapy stimulates the proliferation of a variety of types of cells. However, very little is known about its effect on stem cells from human exfoliated deciduous teeth (SHED). Objective This study aimed to evaluate the influence of different laser therapy energy densities on SHED viability and proliferation. Material and Methods SHED were irradiated according to the groups: I (1.2 J/cm2 - 0.5 mW – 10 s), II (2.5 J/cm2 – 10 mW – 10 s), III (3.7 J/cm2 – 15 mW – 10 s), IV (5.0 J/cm2 – 20 mW – 10 s), V (6.2 J/cm2 – 25 mW – 10 s), and VI (not irradiated – control group). Cell viability was assessed 6 and 24 h after irradiation measuring the mitochondrial activity and using the Crystal Violet assay. Cell proliferation was assessed after 24, 48, and 72 h of irradiation by SRB assay. Results MTT assay demonstrated differences from 6 to 24 hours after irradiation. After 24 h, groups I and IV showed higher absorbance values than those of control group. Crystal Violet assay showed statistically differences in the absorbance rate from 6 to 24 h after irradiation for groups III and VI. At 24 h after irradiation, Group III absorbance rate was greater than that of groups I, II, and IV. Group VI absorbance rate was greater than that of groups I and IV. SRB assay showed that the group I had higher rates than those of groups II, III, V, and VI, at 24 h after irradiation. After 48 h, group I exhibited the greatest cell proliferation rate followed by groups III, V, and VI. After 72 h, group III exhibited the lowest cell proliferation rate than those of groups II, IV, and V. Conclusions The Low-Level Laser Therapy energy densities used in this study did not cause loss of cell viability and stimulated SHED proliferation within the parameters described in this study. PMID:27556203

Temperature dependence of the isotope chemistry of the heavy elements.

PubMed Central

Bigeleisen, J

1996-01-01

The temperature coefficient of equilibrium isotope fractionation in the heavy elements is shown to be larger at high temperatures than that expected from the well-studied vibrational isotope effects. The difference in the isotopic behavior of the heavy elements as compared with the light elements is due to the large nuclear isotope field shifts in the heavy elements. The field shifts introduce new mechanisms for maxima, minima, crossovers, and large mass-independent isotope effects in the isotope chemistry of the heavy elements. The generalizations are illustrated by the temperature dependence of the isotopic fractionation in the redox reaction between U(VI) and U(IV) ions. PMID:8790340

Impact of vision impairment and self-reported barriers to vision care: The views of elders in Nuwara Eliya district, Sri Lanka.

PubMed

Holmes, W; Shajehan, R; Kitnasamy, S; Abeywickrama, C; Arsath, Y; Gnanaraj, F; Inbaraj, S; Jayakody, G; Durrant, K; Luchters, S

2018-05-01

The growing burden of vision impairment (VI) among older people is a development challenge in Asian countries. This study aimed to understand older people's views and experiences about the impact of VI and barriers to eye care to inform policies to address this challenge. We conducted 12 focus group discussions in 2013 with retired Tamil and Sinhala elders in Nuwara Eliya district, Sri Lanka (n = 107). Data were analysed thematically. Older people described the broad impacts VI has on their lives. They worry about becoming dependent. VI restricts their ability to contribute to their families and communities, access information, socialise, maintain their health, and earn. Barriers to eye care services include transport difficulties, costs of treatment, fear, lack of knowledge, waiting times, and health staff attitudes. Older people experience and fear the impacts of VI on their health and well-being. Eye health promotion and care services need strengthening and integration with the primary health care system to address the backlog and growing need among older people in an equitable way. Older people should be consulted about how to overcome the economic, social, and cultural barriers to access to eye care and to minimise the impact of VI. FGDs: focus group discussions; GBD: global burden of disease; NCDs: non-communicable diseases; VI: vision impairment.

Synthesis, characterization and application of Lagerstroemia speciosa embedded magnetic nanoparticle for Cr(VI) adsorption from aqueous solution.

PubMed

Srivastava, Shalini; Agrawal, Shashi Bhushan; Mondal, Monoj Kumar

2017-05-01

Lagerstroemia speciosa bark (LB) embedded magnetic nanoparticles were prepared by co-precipitation of Fe 2+ and Fe 3+ salt solution with ammonia and LB for Cr(VI) removal from aqueous solution. The native LB, magnetic nanoparticle (MNP), L. speciosa embedded magnetic nanoparticle (MNPLB) and Cr(VI) adsorbed MNPLB particles were characterized by SEM-EDX, TEM, BET-surface area, FT-IR, XRD and TGA methods. TEM analysis confirmed nearly spherical shape of MNP with an average diameter of 8.76nm and the surface modification did not result in the phase change of MNP as established by XRD analysis, while led to the formation of secondary particles of MNPLB with diameter of 18.54nm. Characterization results revealed covalent binding between the hydroxyl group of MNP and carboxyl group of LB particles and further confirmed its physico-chemical nature favorable for Cr(VI) adsorption. The Cr(VI) adsorption on to MNPLB particle as an adsorbent was tested under different contact time, initial Cr(VI) concentration, adsorbent dose, initial pH, temperature and agitation speed. The results of the equilibrium and kinetics of adsorption were well described by Langmuir isotherm and pseudo-second-order model, respectively. The thermodynamic parameters suggest spontaneous and endothermic nature of Cr(VI) adsorption onto MNPLB. The maximum adsorption capacity for MNPLB was calculated to be 434.78mg/g and these particles even after Cr(VI) adsorption were collected effortlessly from the aqueous solution by a magnet. The desorption of Cr(VI)-adsorbed MNPLB was found to be more than 93.72% with spent MNPLB depicting eleven successive adsorption-desorption cycles. Copyright © 2016. Published by Elsevier B.V.

Application of Trianionic Pincer Ligands to Reactions Involving Group VI Alkylidynes, Metal-Metal Multiple Bonds, and Group IV Amides

DTIC Science & Technology

2008-08-01

liberate the alkyne. The following research aims to marry the ideas of Johnson and Mindiola. A high- oxidation state, group VI alkylidyne will be...cycle. The trianionic pincer ligands designed previously by the Veige group , in particular, the previously reported OCO pincer ligand [3,3”-di-tert... nonequivalence of the isopropyl groups in the 1H NMR spectrum. The W-Calkylidene distance of 1.917(8) Å and the W-Calkylidene-C angle of 139.9(7)° are not

Antiurolithic effect of olive oil in a mouse model of ethylene glycol-induced urolithiasis.

PubMed

Alenzi, Mohammed; Rahiman, Shaik; Tantry, Bilal Ahmad

2017-05-01

At present, commercially available antiurolithic drugs have more adverse effects than potential therapeutic or preventive effects with chronic use. With this in mind, the present study was designed to assess the antiurolithic effect of olive oil in a mouse model of ethylene glycol (EG)-induced urolithiasis. Adult albino mice were divided into 6 groups. Group I was fed the vehicle only. Group II was supplemented with 0.75% EG alone in drinking water during the experimental period to initiate deposition of calcium oxalate in kidneys, which leads to urolithiasis in animals. Groups III (olive oil control group) through V were fed olive oil orally at various doses during the experimental period. Group VI received cystone (750 mg/kg). Groups IV-VI additionally received 0.75% EG in drinking water ad libitum. SPSS ver.17.0 was used for statistical analysis. The study results showed significantly higher levels of serum urea, uric acid, and creatinine (p<0.05) in group II than in groups III-VI and I. Administration of olive oil at different doses restored the elevated serum parameters in groups IV and V compared with group II. Urine and kidney calcium, oxalate, and phosphate levels in groups IV-VI were significantly lower (p<0.05) than in animals with EG-induced urolithiasis (group II). Group V mice showed a significant restoration effect on serum as well as urine and kidney parameters compared with group II. Supplementation with olive oil (1.7 mL/kg body weight) reduced and prevented the growth of urinary stones, possibly by inhibiting renal tubular membrane damage due to peroxidative stress induced by hyperoxaluria.

The Hubble Space Telescope quasar absorption line key project. 6: Properties of the metal-rich systems

NASA Technical Reports Server (NTRS)

Bergeron, Jacqueline; Petitjean, Patrick; Sargent, W. L. W.; Bahcall, John N.; Boksenberg, Alec; Hartig, George F.; Jannuzi, Buell T.; Kirhakos, Sofia; Savage, Blair D.; Schneider, Donald P.

1994-01-01

We present an analysis of the properties of a sample of 18 metal-rich, low-redshift z(sub abs) much less than z(sub em) absorbers seen in low- and medium-resolution spectra obtained for the Quasar Absorption Line Key Project with the Hubble Space Telescope Faint Object Spectrograph (HST/FOS). For most of the C IV and Lyman-limit systems, observations in the optical wavelength range of the expected associated Mg II absorption are available. As at high redshift (z approximately 2), there are two subclasses of absorbers which are characterized by the presence or absence of MG II absorption. However, some low-redshift Mg II and Fe absorptions originate from regions optically thin to UV ionizing photons and thus, at low redshift, the low-ionization systems do not always trace high opacities, as is the case at high redshift. This implies that the mean ionization state of metal-rich, optically thin absorbing clouds falls with decreasing redshift, which is consistent with the hypothesis that the gas is photoionized by the metagalactic UV background radiation field. Two main constraints are derived from the analysis of the Lyman-limit sample, assuming photoionization models are valid. First, a low opacity to ionizing photons (tau(sub LL) approximately less than 1), as observed for several Mg II-Fe II systems at z approximately 0.5, sets limits on the ionization level of hydrogen, thus on the total hydrogen column density and the heavy element abundances, (Z/H) approximately -0.5 to -0.3. Second, the dimensions of individual Mg II clouds are smaller than at high redshift by a factor 3-10. At z approximately greater than 0.6, the O VI absorption doublet is detected in four of the five z(sub abs) much less than z(sub em) systems for which the O VI wavelength range has been observed, whereas the associated N V doublet is detected in only two cases. This suggests that the presence of a high-ionization O VI phase is a general property of z approximately 0.6-1 absorption systems, as is also probably the case at high redshift. These O VI absorbers can be ionized by the UV metagalactic field if their density is low, nH approximately less than 3 x 10(exp -4)/cc. The O VI phase would then be a homogeneous region of large extent, r approximately greater than 50 kpc. A detailed photoionization model of the z(sub abs) = 0.791 absorber toward PKS 2145+06 confirms the properties derived from the Mg II, C IV, O VI, and Lyman-limit samples. The galaxy causing this extensive metal-line absorption system has been identified, and its possible contribution to the UV ionizing flux does not substantially modify the value of the derived parameters. The heavy element abundances are about half the solar values. The O VI region has a density about 20 times lower than the Mg II clouds and a size of approximately 70 kpc. Alternatively, the high-ionization phase could be collisionally ionized and trace gas associated with a possible group of galaxies at the absorber redshift.

Domestic Production Issues in Chromium and Platinum-Group Metals

DTIC Science & Technology

1988-09-01

iridium, and minor amounts of osmium. 12 Uses. Platinum-group metals (PGM) are critical as catalysts in fossil fuel processing and electronic...metals (PGM) were then described as critical in fossil fuel production, and in electronic and electrical components. The international market is...this research process . ii Table of Contents Page Preface.. .............. ii List of Figures ................ vi List of Tables ................ vi

Does Central Vision Loss Impair Visual Search Performance of Adults More than Children?

PubMed

Satgunam, PremNandhini; Luo, Gang

2018-05-01

In general, young adults with normal vision show the best visual search performance when compared with children and older adults. Through our study, we show that this trend is not observed in individuals with vision impairment. An interaction effect of vision impairment with visual development and aging is observed. Performance in many visual tasks typically shows improvement with age until young adulthood and then declines with aging. Using a visual search task, this study investigated whether a similar age effect on performance is present in people with central vision loss. A total of 98 participants, 37 with normal sight (NS) and 61 with visual impairment (VI) searched for targets in 150 real-world digital images. Search performance was quantified by an integrated measure combining speed and accuracy. Participant ages ranged from 5 to 74 years, visual acuity from -0.14 (20/14.5) to 1.16 logMAR (20/290), and log contrast sensitivity (CS) from 0.48 to 2.0. Data analysis was performed with participants divided into three age groups: children (aged <14 years, n = 25), young adults (aged 14 to 45 years, n = 47), and older adults (aged >45 years, n = 26). Regression (r = 0.7) revealed CS (P < .001) and age (P = .003) were significant predictors of search performance. Performance of VI participants was normalized to the age-matched average performance of the NS group. In the VI group, it was found that children's normalized performance (52%) was better than both young (39%, P = .05) and older (40%, P = .048) adults. Unlike NS participants, young adults in the VI group may not have search ability superior to children with VI, despite having the same level of visual functions (quantified by visual acuity and CS). This could be because of vision impairment limiting the developmental acquisition of the age dividend for peak performance. Older adults in the VI group had the worst performance, indicating an interaction of aging.

Natural history and galsulfase treatment in mucopolysaccharidosis VI (MPS VI, Maroteaux-Lamy syndrome)--10-year follow-up of patients who previously participated in an MPS VI Survey Study.

PubMed

Giugliani, Roberto; Lampe, Christina; Guffon, Nathalie; Ketteridge, David; Leão-Teles, Elisa; Wraith, James E; Jones, Simon A; Piscia-Nichols, Cheri; Lin, Ping; Quartel, Adrian; Harmatz, Paul

2014-08-01

Mucopolysaccharidosis VI (MPS VI) is a clinically heterogeneous and progressive disorder with multiorgan manifestations caused by deficient N-acetylgalactosamine-4-sulfatase activity. A cross-sectional Survey Study in individuals (n = 121) affected with MPS VI was conducted between 2001 and 2002 to establish demographics, urinary glycosaminoglycan (GAG) levels, and clinical progression of disease. We conducted a Resurvey Study (ClinicalTrials.gov: NCT01387854) to obtain 10-year follow-up data, including medical histories and clinical assessments (n = 59), and survival status over 12 years (n = 117). Patients received a mean (SD) of 6.8 (2.2) years of galsulfase ERT between baseline (Survey Study) and follow-up. ERT patients increased in height by 20.4 cm in the 4-7-year-old baseline age group and by 16.8 cm in the 8-12-year-old baseline age group. ERT patients <13 years-old demonstrated improvement in forced vital capacity (FVC) by 68% and forced expiratory volume in 1 sec (FEV1) by 55%, and those ≥13 years-old increased FVC by 12.8% and maintained FEV1. Patients with >200 µg/mg baseline uGAG levels increased FVC by 48% in the <13-year-old baseline age group and by 15% in the ≥13-year-old baseline age group. ERT patients who completed the 6-min walk test demonstrated a mean (SD) increase of 65.7 (100.6) m. Cardiac outcomes did not significantly improve or worsen. Observed mortality rate among naïve patients was 50% (7/14) and 16.5% (17/103) in the ERT group (unadjusted hazard ratio, 0.24; 95% CI, 0.10-0.59). Long-term galsulfase ERT was associated with improvements in pulmonary function and endurance, stabilized cardiac function and increased survival. © 2014 Wiley Periodicals, Inc.

Bioremediation of chromium by the yeast Pichia guilliermondii: toxicity and accumulation of Cr (III) and Cr (VI) and the influence of riboflavin on Cr tolerance.

PubMed

Ksheminska, Helena; Jaglarz, Anita; Fedorovych, Daria; Babyak, Lyubov; Yanovych, Dmytro; Kaszycki, Pawel; Koloczek, Henryk

2003-01-01

A comparative study has been made on the sensitivity of the yeast Pichia guilliermondii to Cr (III) and Cr (VI) as well as on the Cr uptake potential at growth-inhibitory concentrations of chromium. The strains used in the study were either isolated from natural sources or obtained from a laboratory strain collection. The results show that most of the natural strains were more tolerant to chromium and were able to grow in the presence of 5 mM Cr (III) or 0.5 mM Cr (VI), that is at concentrations which substantially inhibited the growth of laboratory strains. The cellular Cr content after treatment was similar for both strain types and ranged from 1.2-4.0 mg/g d.w. and 0.4-0.9 mg/g d.w., for Cr (III) and Cr (VI) forms, respectively, however, in one case of a natural strain it reached the value of 10 mg Cr (III)/g dry mass. Natural-source strains were grouped into four groups based on the yeasts' differential response to Cr (III) and Cr (VI). Hexavalent Cr-resistant mutants of a P. giuilliermondii laboratory strain, which revealed markedly changed capabilities of chromium accumulation, were obtained by means of UV-induced mutagenesis. Cr (VI) treatment triggered oversynthesis of riboflavin and the addition of exogenous riboflavin increased P. guilliermondii resistance to both Cr (III) and Cr (VI). Electrophoretic protein profiles revealed the induction and/or suppression of several proteins in response to toxic Cr (VI) levels.

Pressure-flow specificity of inspiratory muscle training.

PubMed

Tzelepis, G E; Vega, D L; Cohen, M E; Fulambarker, A M; Patel, K K; McCool, F D

1994-08-01

The inspiratory muscles (IM) can be trained by having a subject breathe through inspiratory resistive loads or by use of unloaded hyperpnea. These disparate training protocols are characterized by high inspiratory pressure (force) or high inspiratory flow (velocity), respectively. We tested the hypothesis that the posttraining improvements in IM pressure or flow performance are specific to training protocols in a way that is similar to force-velocity specificity of skeletal muscle training. IM training was accomplished in 15 normal subjects by use of three protocols: high inspiratory pressure-no flow (group A, n = 5), low inspiratory pressure-high flow (group B, n = 5), and intermediate inspiratory pressure and flow (group C, n = 5). A control group (n = 4) did no training. Before and after training, we measured esophageal pressure (Pes) and inspiratory flow (VI) during single maximal inspiratory efforts against a range of external resistances including an occluded airway. Efforts originated below relaxation volume (Vrel), and peak Pes and VI were measured at Vrel. Isovolume maximal Pes-VI plots were constructed to assess maximal inspiratory pressure-flow performance. Group A (pressure training) performed 30 maximal static inspiratory maneuvers at Vrel daily, group B (flow training) performed 30 sets of three maximal inspiratory maneuvers with no added external resistance daily, and group C (intermediate training) performed 30 maximal inspiratory efforts on a midrange external resistance (7 mm ID) daily. Subjects trained 5 days/wk for 6 wk. Data analysis included comparison of posttraining Pes-VI slopes among training groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Theoretical study of inverted sandwich type complexes of 4d transition metal elements: interesting similarities to and differences from 3d transition metal complexes.

PubMed

Kurokawa, Yusaku I; Nakao, Yoshihide; Sakaki, Shigeyoshi

2012-03-08

Inverted sandwich type complexes (ISTCs) of 4d metals, (μ-η(6):η(6)-C(6)H(6))[M(DDP)](2) (DDPH = 2-{(2,6-diisopropylphenyl)amino}-4-{(2,6-diisopropylphenyl)imino}pent-2-ene; M = Y, Zr, Nb, Mo, and Tc), were investigated with density functional theory (DFT) and MRMP2 methods, where a model ligand AIP (AIPH = (Z)-1-amino-3-imino-prop-1-ene) was mainly employed. When going to Nb (group V) from Y (group III) in the periodic table, the spin multiplicity of the ground state increases in the order singlet, triplet, and quintet for M = Y, Zr, and Nb, respectively, like 3d ISTCs reported recently. This is interpreted with orbital diagram and number of d electrons. However, the spin multiplicity decreases to either singlet or triplet in ISTC of Mo (group VI) and to triplet in ISTC of Tc (group VII), where MRMP2 method is employed because the DFT method is not useful here. These spin multiplicities are much lower than the septet of ISTC of Cr and the nonet of that of Mn. When going from 3d to 4d, the position providing the maximum spin multiplicity shifts to group V from group VII. These differences arise from the size of the 4d orbital. Because of the larger size of the 4d orbital, the energy splitting between two d(δ) orbitals of M(AIP) and that between the d(δ) and d(π) orbitals are larger in the 4d complex than in the 3d complex. Thus, when occupation on the d(δ) orbital starts, the low spin state becomes ground state, which occurs at group VI. Hence, the ISTC of Nb (group V) exhibits the maximum spin multiplicity.

Aminopyridine modified Spirulina platensis biomass for chromium(VI) adsorption in aqueous solution.

PubMed

Bayramoglu, Gulay; Akbulut, Aydin; Arica, M Yakup

Chemical modification of Spirulina platensis biomass was realized by sequential treatment of algal surface with epichlorohydrin and aminopyridine. Adsorptive properties of Cr(VI) ions on native and aminopyridine modified algal biomass were investigated by varying pH, contact time, ionic strength, initial Cr(VI) concentration, and temperature. FTIR and analytical analysis indicated that carboxyl and amino groups were the major functional groups for Cr(VI) ions adsorption. The optimum adsorption was observed at pH 3.0 for native and modified algal biomasses. The adsorption capacity was found to be 79.6 and 158.7 mg g(-1), for native and modified algal biomasses, respectively. For continuous system studies, the experiments were conducted to study the effect of important design parameters such as flow rate and initial concentration of metal ions, and the maximum sorption capacity was observed at a flow rate of 50 mL h(-1), and Cr(VI) ions concentration 200 mg L(-1) with modified biomass. Experimental data fitted a pseudo-second-order equation. The regeneration performance was observed to be 89.6% and 94.3% for native and modified algal biomass, respectively.

Synthesis, structure and DFT study of cymantrenyl Fischer carbene complexes of group VI and VII transition metals

NASA Astrophysics Data System (ADS)

Fraser, Roan; van Rooyen, Petrus H.; Landman, Marilé

2016-02-01

Bi- and trimetallic carbene complexes of group VI and VII transition metals (Cr, Mo, W, Mn and Re), with CpMn(CO)3 as the initial synthon, have been synthesised according to the classical Fischer methodology. Crystal structures of the novel carbene complexes with general formula [Mx(CO)y-1{C(OEt)(MnCp(CO)3)}], where x = 1 then y = 3 or 6; x = 2 then y = 10, of the complexes are reported. A density functional theory (DFT) study was undertaken to determine natural bonding orbitals (NBOs) and conformational as well as isomeric aspects of the polymetallic complexes. Application of the second-order perturbation theory (SOPT) of the natural bond orbital (NBO) method revealed stabilizing interactions between the methylene C-H bonds and the carbonyl ligands of the carbene metal moiety. These stabilization interactions show a linear decrease for the group VI metal carbene complexes down the group.

[New perspectives in biomonitoring of metallic elements: the example of hexavalent chromium].

PubMed

Mutti, A; De Palma, G; Goldoni, M

2012-01-01

Plating industry is an important productive sector in all the national territory, because of its contribution to a high number of industrial products and crafts. In the chrome plating sector there is a specific chemical risk due to the exposure to compounds containing hexavalent Chromium [Cr(VI)]. Exhaled breath condensate (EBC) has been used to study both acute and long term exposure to Cr(VI) in chrome plating workers. Cr-EBC correlates with specific oxidative stress biomarkers. Moreover, both total Cr and its hexavalent fraction can be measured in EBC, which therefore is a promising biological fluid to assess the absorbed dose at the target organ level, the pulmonary reduction kinetics of Cr(VI) and in general its local pneumotoxic effects. EBC collection and analysis could give additional information to the traditional measures performed during biomonitoring.

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

USGS Publications Warehouse

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

2003-01-01

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

Common visual problems in children with disability.

PubMed

Salt, Alison; Sargent, Jenefer

2014-12-01

Children with disability are at a substantially higher risk of visual impairment (VI) (10.5% compared with 0.16%) but also of ocular disorders of all types, including refractive errors and strabismus. The aetiology of VI in children with disability reflects that of the general population and includes cerebral VI, optic atrophy, as well as primary visual disorders such as retinal dystrophies and structural eye anomalies. VI and other potentially correctable ocular disorders may not be recognised without careful assessment and are frequently unidentified in children with complex needs. Although assessment may be more challenging than in other children, identifying these potential additional barriers to learning and development may be critical. There is a need to develop clearer guidelines, referral pathways and closer working between all professionals involved in the care of children with disability and visual disorders to improve our focus on the assessment of vision and outcomes for children with disability. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Investigation of equilibrium and kinetics of Cr(VI) adsorption by dried Bacillus cereus using response surface methodology.

PubMed

Yang, Kai; Zhang, Jing; Yang, Tao; Wang, Hongyu

2016-01-01

In this study, response surface methodology (RSM) based on three-variable-five-level central composite rotatable design was used to analyze the effects of combined and individual operating parameters (biomass dose, initial concentration of Cr(VI) and pH) on the Cr(VI) adsorption capacity of dried Bacillus cereus. A quadratic polynomial equation was obtained to predict the adsorbed Cr(VI) amount. Analysis of variance showed that the effect of biomass dose was the key factor in the removal of Cr(VI). The maximum adsorbed Cr(VI) amount (30.93 mg g(-1)) was found at 165.30 mg L(-1), 2.96, and 3.01 g L(-1) for initial Cr(VI) concentration, pH, and biosorbent dosage, respectively. The surface chemical functional groups and microstructure of unloaded and Cr(VI)-loaded dried Bacillus cereus were identified by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. Besides, the results gained from these studies indicated that Langmuir isotherm and the second-order rate expression were suitable for the removal of Cr(VI) from wastewater. The results revealed RSM was an effective method for optimizing biosorption process, and dried Bacillus cereus had a remarkable performance on the removal of Cr(VI) from wastewater.

Degradation of endocrine disrupting chemicals in aqueous solution by interaction of photocatalytic oxidation and ferrate (VI) oxidation.

PubMed

Li, C; Li, X Z

2007-01-01

In this study, the degradation of bisphenol A in aqueous suspension by interaction of photocatalytic oxidation and ferrate(VI) oxidation was investigated under different conditions. The results indicate that the formation of Fe(V) and Fe(IV) is in the photocatalytic reduction of Fe(VI) by electron (ecb-) on the surface of TiO2. The oxidation efficiency of the photocatalytic oxidation in the presence of Fe(VI) was much greater than that without. In addition, the decomposition of Fe(VI) under different conditions was also investigated. The results indicate that the Fe(VI) reduction was accelerated by photocatalytic reaction and the adsorption capacity of Fe(VI) on TiO2 surface decreased as pH increased. The characteristics of solid potassium ferrate prepared were investigated by X-ray diffraction. It was found that the potassium ferrate solid has a tetrahedral structure with a space group of D2h (Pnma) and a = 7.705 A, b = 5.863 A, and c = 10.36 A.

First Detection of Krypton and Xenon in a White Dwarf

NASA Astrophysics Data System (ADS)

Werner, Klaus; Rauch, Thomas; Ringat, Ellen; Kruk, Jeffrey W.

2012-07-01

We report on the first detection of the noble gases krypton (Z = 36) and xenon (54) in a white dwarf. About 20 Kr VI- VII and Xe VI- VII lines were discovered in the ultraviolet spectrum of the hot DO-type white dwarf RE 0503-289. The observations, performed with the Far Ultraviolet Spectroscopic Explorer, also reveal highly ionized photospheric lines from other trans-iron group elements, namely Ga (31), Ge (32), As (33), Se (34), Mo (42), Sn (50), Te (52), and I (53), from which gallium and molybdenum are new discoveries in white dwarfs, too. For Kr and Xe, we performed an NLTE analysis and derived mass fractions of log Kr = -4.3 ± 0.5 and log Xe = -4.2 ± 0.6, corresponding to an enrichment by factors of 450 and 3800, respectively, relative to the Sun. The origin of the large overabundances is unclear. We discuss the roles of neutron-capture nucleosynthesis in the precursor star and radiation-driven diffusion. It is possible that diffusion is insignificant and that the observed metal abundances constrain the evolutionary history of the star. Its hydrogen deficiency may be the consequence of a late helium-shell flash or a binary white dwarf merger.

Biosorption of Cr(VI) and As(V) at high concentrations by organic and inorganic wastes

NASA Astrophysics Data System (ADS)

María Rivas Pérez, Ivana; Paradelo Núñez, Remigio; Nóvoa Muñoz, Juan Carlos; Arias Estévez, Manuel; José Fernández Sanjurjo, María; Álvarez Rodríguez, Esperanza; Núñez Delgado, Avelino

2016-04-01

The potential reutilization of several wastes as biosorbents for As(V) and Cr(VI) has been assessed in batch-type experiments. The materials studied were one inorganic: mussel shell, and three organic: pine bark, oak ash and hemp waste. Batch experiments were performed in order to determine the removal capacity of the wastes under conditions of high As(V) and Cr(VI) loads. For this, 3 g of each waste material were added with 30 mL NaNO3 0.01 M dissolutions containing 0, 0.5, 1.5, 3 and 6 mmol As(V) L-1 or Cr(VI) L-1, prepared from analytical grade Na2HAsO4 or K2Cr2O7. The resulting suspensions were shaken for 24 h, centrifuged and filtered. Once each batch experiment corresponding to the sorption trials ended, each individual sample was added with 30 mL of NaNO3 0.01 M to desorb As(V) or Cr(VI), shaken for 24 h, centrifuged and filtered as in the sorption trials. Oak ash showed high sorption (>76%) and low desorption (<7%) for As(V), which was lower on mussel shell (<31%), hemp waste (<16%) and pine bark (<9.9%). In turn, pine bark showed the highest Cr(VI) sorption (>98%) with very low desorption (<0.5%), followed by oak ash (27% sorption), and hemp waste and mussel shell, that presented very low Cr(VI) sorption (<10%). Sorption data for both elements were better described by the Freundlich than by the Langmuir model. The variable results obtained for the removal of the two anionic contaminants for a given sorbent suggest that different mechanisms govern removal from the solution in each case. In summary, oak ash would be an efficient sorbent material for As(V), but not for Cr(VI), while pine bark would be the best sorbent for Cr(VI) removal.

The U(VI) speciation influenced by a novel Paenibacillus isolate from Mont Terri Opalinus clay.

PubMed

Lütke, Laura; Moll, Henry; Bachvarova, Velina; Selenska-Pobell, Sonja; Bernhard, Gert

2013-05-21

Bacterial cell walls have a high density of ionizable functional groups available for U(VI) binding, hence have a great potential to affect the speciation of this contaminant in the environment. The studied strain of the genus Paenibacillus is a novel isolate originating from the Mont Terri Opalinus clay formations (Switzerland) which are currently investigated as a potential host rock for future nuclear waste storage. U(VI) binding to the cell surface functional groups was studied by potentiometry combined with time-resolved laser-induced fluorescence spectroscopy (TRLFS). Four bacterial U(VI) surface complexes were identified: R-COO-UO2(+), R-O-PO3-UO2, R-O-PO3H-UO2(+), and (R-O-PO3)2-UO2(2-). The corresponding complex stability constants were calculated to be 5.33 ± 0.08, 8.89 ± 0.04, 12.92 ± 0.05, and 13.62 ± 0.08, respectively. Hence UO2(2+) displays a moderate to strong interaction with the bacterial surface functional groups. In the acidic pH range (pH 3) UO2(2+) binding onto the cell envelope is governed by coordination to hydrogen phosphoryl sites. Upon increasing the pH an increasing coordination of UO2(2+) to carboxylic and deprotonated phosphoryl sites was found. At a pH greater than 7 uranyl hydroxides dominate the speciation. Additionally the bacteria-mediated release of inorganic phosphate in dependence on [U(VI)] at different pH values was studied to assess the influence of phosphate release on U(VI) mobilization.

Unique reversibility in extraction mechanism of U compared to solvent extraction for sorption of U(VI) and Pu(IV) by a novel solvent impregnated resin containing trialkyl phosphine oxide functionalized ionic liquid.

PubMed

Paramanik, M; Panja, S; Dhami, P S; Yadav, J S; Kaushik, C P; Ghosh, S K

2018-07-15

Novel Solvent Impregnated Resin (SIR) material was prepared by impregnating a trialkyl phosphine oxide functionalized ionic liquid (IL) into an inert polymeric material XAD-7. A series of SIR materials were prepared by varying the IL quantity. Sorption of both U(VI) and Pu(IV) were found to increase with increasing IL concentration in SIR up to an optimum IL concentration of 435 mg g -1 of SIR beyond which no effect of IL concentration was observed. A change of mechanism of sorption for U(VI) by SIR was observed in comparison to solvent extraction. The dependency of U(VI) sorption with nitric acid concentration showed a reverse trend compared to solvent extraction studies while for Pu(IV) the trend remained same as observed with solvent extraction. Sorption of both the radionuclides was found to follow pseudo second order mechanism and Langmuir adsorption isotherm. Distribution co-efficient measurements on IL impregnated SIR showed highly selective sorption of U(VI) and Pu(IV) over other trivalent f-elements and fission products from nitric acid medium. Copyright © 2018 Elsevier B.V. All rights reserved.

Removal of hexavalent chromium [Cr(VI)] from aqueous solutions by the diatomite-supported/unsupported magnetite nanoparticles.

PubMed

Yuan, Peng; Liu, Dong; Fan, Mingde; Yang, Dan; Zhu, Runliang; Ge, Fei; Zhu, JianXi; He, Hongping

2010-01-15

Diatomite-supported/unsupported magnetite nanoparticles were prepared by co-precipitation and hydrosol methods, and characterized by X-ray diffraction, nitrogen adsorption, elemental analysis, differential scanning calorimetry, transmission electron microscopy and X-ray photoelectron spectroscopy. The average sizes of the unsupported and supported magnetite nanoparticles are around 25 and 15 nm, respectively. The supported magnetite nanoparticles exist on the surface or inside the pores of diatom shells, with better dispersing and less coaggregation than the unsupported ones. The uptake of hexavalent chromium [Cr(VI)] on the synthesized magnetite nanoparticles was mainly governed by a physico-chemical process, which included an electrostatic attraction followed by a redox process in which Cr(VI) was reduced into trivalent chromium [Cr(III)]. The adsorption of Cr(VI) was highly pH-dependent and the kinetics of the adsorption followed a pseudo-second-order model. The adsorption data of diatomite-supported/unsupported magnetite fit well with the Langmuir isotherm equation. The supported magnetite showed a better adsorption capacity per unit mass of magnetite than unsupported magnetite, and was more thermally stable than their unsupported counterparts. These results indicate that the diatomite-supported/unsupported magnetite nanoparticles are readily prepared, enabling promising applications for the removal of Cr(VI) from aqueous solution.

Chromium removal from electroplating wastewater by coir pith.

PubMed

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

2007-03-22

Coir pith is a by-product from padding used in mattress factories. It contains a high amount of lignin. Therefore, this study investigated the use of coir pith in the removal of hexavalent chromium from electroplating wastewater by varying the parameters, such as the system pH, contact time, adsorbent dosage, and temperature. The maximum removal (99.99%) was obtained at 2% (w/v) dosage, particle size <75microm, at initial Cr(VI) 1647mgl(-1), system pH 2, and an equilibrium time of 18h. The adsorption isotherm of coir pith fitted reasonably well with the Langmuir model. The maximum Cr(VI) adsorption capacity of coir pith at 15, 30, 45 and 60 degrees C was 138.04, 197.23, 262.89 and 317.65mgCr(VI)g(-1) coir pith, respectively. Thermodynamic parameters indicated an endothermic process and the adsorption process was favored at high temperature. Desorption studies of Cr(VI) on coir pith and X-ray absorption near edge structure (XANES) suggested that most of the chromium bound on the coir pith was in Cr(III) form due to the fact that the toxic Cr(VI) adsorbed on the coir pith by electrostatic attraction was easily reduced to less toxic Cr(III). Fourier transform infrared (FT-IR) spectrometry analysis indicated that the carbonyl (CO) groups and methoxy (O-CH(3)) groups from the lignin structure in coir pith may be involved in the mechanism of chromium adsorption. The reduced Cr(III) on the coir pith surface may be bound with CO groups and O-CH(3) groups through coordinate covalent bonding in which a lone pair of electrons in the oxygen atoms of the methoxy and carbonyl groups can be donated to form a shared bond with Cr(III).

Amelioration of cisplatin-induced nephrotoxicity by ethanolic extract of Bauhinia purpurea: An in vivo study in rats.

PubMed

Rana, Md Azmat; Khan, Rahat Ali; Nasiruddin, Mohammad; Khan, Aijaz Ahmed

2016-01-01

Our objective is to study the nephroprotective activity and antioxidant potential of Bauhinia purpurea unripe pods and bark against cisplatin-induced nephrotoxicity. Healthy adult albino rats of either sex (150-200 g) were randomly divided into six groups of six animals each Group I (vehicle control) and Group II (negative control). Group III (BBE200) and Group IV (BBE400) were administered the ethanolic extract of Bauhinia purpurea bark in doses of 200 and 400 mg/kg/day p.o., respectively, and Group V (BPE200) and Group VI (BPE400) were administered the ethanolic extract of Bauhinia purpurea unripe pods at doses of 200 and 400 mg/kg/day p.o., respectively. All the treatments were given for nine days. Cisplatin in a single dose of 6 mg/kg i.p. was given on the 4 th day to all groups, except the vehicle control group. On the 10 th day, blood and urine were collected for biochemical tests and the rats were sacrificed. The kidney was removed for histology and lipid peroxidation-antioxidant test. Cisplatin caused nephrotoxicity as evidenced by elevated blood urea, serum creatinine and urine glucose, and there was decreased creatinine clearance in Group II as compared with Group I. Administration of BBE and BPE at doses of 200 and 400 mg/kg in Group III and Group VI caused a dose-dependant reduction in the rise of blood urea, serum creatinine and urine glucose, and there was a dose-dependant increase in creatinine clearance compared with Group II. There was increased catalase and glutathione and decreased malondialdehyde levels in Group II, while BBE 400 (Group IV) and BPE 400 (Group VI) treatments significantly reversed the changes toward normal values. Histological examination of the kidney revealed protection in Group IV and Group VI compared with Group II. The ethanolic extract of Bauhinia purpurea unripe pods and bark has a nephroprotective activity against cisplatin-induced nephrotoxicity in rats.

In vitro microleakage of glass-ionomer composite resin hybrid materials.

PubMed

Rodrigues, J A; De Magalhães, C S; Serra, M C; Rodrigues Júnior, A L

1999-01-01

The purpose of this study was to evaluate the microleakage of six glass-ionomer composite resin hybrid materials compared with a glass-ionomer cement and a composite resin. Standardized class 5 dentin cavities were prepared on root surfaces of 240 extracted human teeth that were randomly assigned to eight groups and restored using the following restorative systems: (I) Vitremer, (II) Compoglass, (III) Photac-Fil Aplicap, (IV) Variglass, (V) Dyract, (VI) Fuji II LC, (VII) Ketac-Fil Aplicap, and (VIII) Z100. The teeth were thermocycled, placed in a 2% methylene blue solution, and sectioned with diamond disks. Dye penetration was scored on a scale of 0-3. Results showed no significant differences among groups VIII, IV, I, V, VI, III, and II. There were also no significant differences among groups VI, III, II, and VII.

Experimental Characterization of Microfabricated VirtualImpactor Efficiency

EPA Science Inventory

The Air-Microfluidics Group is developing a microelectromechanical systems-based direct reading particulate matter (PM) mass sensor. The sensor consists of two main components: a microfabricated virtual impactor (VI) and a PM mass sensor. The VI leverages particle inertia to sepa...

Molecular Mechanisms of RNA-Targeting by Cas13-containing Type VI CRISPR-Cas Systems.

PubMed

O'Connell, Mitchell

2018-06-22

Prokaryotic adaptive immune systems use CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats) and CRISPR associated (Cas) proteins for RNA-guided cleavage of foreign genetic elements. The focus of this review, Type VI CRISPR-Cas systems, include a single protein known as Cas13 (formerly C2c2), that when assembled with a crRNA forms a crRNA-guided RNA-targeting effector complex. Type VI CRISPR-Cas systems can be divided into four subtypes (A-D) based on Cas13 phylogeny. All Cas13 proteins studied to date possess two enzymatically distinct ribonuclease activities that are required for optimal interference. One RNase is responsible for pre-crRNA processing to form mature Type VI interference complexes, while the other RNase activity provided by the two HEPN (Higher Eukaryotes and Prokaryotes Nucleotide-binding) domains, is required for degradation of target RNA during viral interference. In this review, I will compare and contrast what is known about the molecular architecture and behavior of Type VI (A-D) CRISPR-Cas13 interference complexes, how this allows them to carry out their RNA-targeting function, how Type VI accessory proteins are able to modulate Cas13 activity, and how together all of these features have led to the rapid development of a range of RNA-targeting applications. Throughout I will also discuss some of the outstanding questions regarding Cas13's molecular behavior, and its role in bacterial adaptive immunity and RNA-targeting applications. Copyright © 2018. Published by Elsevier Ltd.

Visual Impairment in Preschool Children in the United States: Demographic and Geographic Variations From 2015 to 2060.

PubMed

Varma, Rohit; Tarczy-Hornoch, Kristina; Jiang, Xuejuan

2017-06-01

Visual impairment (VI) in early childhood can significantly impair development. To determine demographic and geographic variations in VI in children aged 3 to 5 years in the United States in 2015 and to estimate projected prevalence through 2060. Descriptive study reporting statistics estimated based on prevalence data from 2 major population-based studies conducted in the United States between 2003 and 2011. Using US census projections, prevalence of VI and cause-specific VI in the better eye were reported by race/ethnicity, state and region, and per capita prevalence of VI by state. The study included preschool children in the United States. Analyses for this study were conducted between February 2016 and March 2017. Prevalence of VI among children aged 3 to 5 years in the United States. In 2015, more than 174 000 children aged 3 to 5 years in the United States were visually impaired. Almost 121 000 of these cases (69%) arose from simple uncorrected refractive error, and 43 000 (25%) from bilateral amblyopia. By 2060, the number of children aged 3 to 5 years with VI is projected to increase by 26%. In 2015, Hispanic white children accounted for the highest number of VI cases (66 000); this group will remain the most affected through 2060, with an increasingly large proportion of cases (37.7% in 2015 and 43.6% in 2060). The racial/ethnic group with the second most VI is projected to shift from non-Hispanic white children (26.3% in 2015 decreasing to 16.5% in 2060) to African American children (24.5% in 2015 and 22.0% in 2060). From 2015 to 2060, the states projected to have the most children with VI are California (26 600 in 2015 and 38 000 in 2060), Texas (21 500 in 2015 and 29 100 in 2060), and Florida (10 900 in 2015 and 13 900 in 2060). These data suggest that the number of preschool children with VI is projected to increase disproportionally, especially among minority populations. Vision screening for refractive error and related eye diseases may prevent a high proportion of preschool children from experiencing unnecessary VI and associated developmental delays.

Visual Impairment in Preschool Children in the United States

PubMed Central

Tarczy-Hornoch, Kristina; Jiang, Xuejuan

2017-01-01

Importance Visual impairment (VI) in early childhood can significantly impair development. Objective To determine demographic and geographic variations in VI in children aged 3 to 5 years in the United States in 2015 and to estimate projected prevalence through 2060. Design, Setting, and Participants Descriptive study reporting statistics estimated based on prevalence data from 2 major population-based studies conducted in the United States between 2003 and 2011. Using US census projections, prevalence of VI and cause-specific VI in the better eye were reported by race/ethnicity, state and region, and per capita prevalence of VI by state. The study included preschool children in the United States. Analyses for this study were conducted between February 2016 and March 2017. Main Outcomes and Measures Prevalence of VI among children aged 3 to 5 years in the United States. Results In 2015, more than 174 000 children aged 3 to 5 years in the United States were visually impaired. Almost 121 000 of these cases (69%) arose from simple uncorrected refractive error, and 43 000 (25%) from bilateral amblyopia. By 2060, the number of children aged 3 to 5 years with VI is projected to increase by 26%. In 2015, Hispanic white children accounted for the highest number of VI cases (66 000); this group will remain the most affected through 2060, with an increasingly large proportion of cases (37.7% in 2015 and 43.6% in 2060). The racial/ethnic group with the second most VI is projected to shift from non-Hispanic white children (26.3% in 2015 decreasing to 16.5% in 2060) to African American children (24.5% in 2015 and 22.0% in 2060). From 2015 to 2060, the states projected to have the most children with VI are California (26 600 in 2015 and 38 000 in 2060), Texas (21 500 in 2015 and 29 100 in 2060), and Florida (10 900 in 2015 and 13 900 in 2060). Conclusions and Relevance These data suggest that the number of preschool children with VI is projected to increase disproportionally, especially among minority populations. Vision screening for refractive error and related eye diseases may prevent a high proportion of preschool children from experiencing unnecessary VI and associated developmental delays. PMID:28472231

Prediction and synthesis of a family of atomic laminate phases with Kagomé-like and in-plane chemical ordering

PubMed Central

Dahlqvist, Martin; Lu, Jun; Meshkian, Rahele; Tao, Quanzheng; Hultman, Lars; Rosen, Johanna

2017-01-01

The enigma of MAX phases and their hybrids prevails. We probe transition metal (M) alloying in MAX phases for metal size, electronegativity, and electron configuration, and discover ordering in these MAX hybrids, namely, (V2/3Zr1/3)2AlC and (Mo2/3Y1/3)2AlC. Predictive theory and verifying materials synthesis, including a judicious choice of alloying M from groups III to VI and periods 4 and 5, indicate a potentially large family of thermodynamically stable phases, with Kagomé-like and in-plane chemical ordering, and with incorporation of elements previously not known for MAX phases, including the common Y. We propose the structure to be monoclinic C2/c. As an extension of the work, we suggest a matching set of novel MXenes, from selective etching of the A-element. The demonstrated structural design on simultaneous two-dimensional (2D) and 3D atomic levels expands the property tuning potential of functional materials. PMID:28776034

The role of Mg dopant on the morphological, structural and optical properties of Mg doped zinc oxide grown through hydrothermal method

NASA Astrophysics Data System (ADS)

Susetyo, P.; Fauzia, V.; Sugihartono, I.

2017-04-01

ZnO nanorods is a low cost II-VI semiconductor compound with huge potential to be applied in optoelectronic devices i.e. light emitting diodes, solar cells, gas sensor, spintronic devices and lasers. In order to improve the electrical and optical properties, group II, III and IV elements were widely investigated as dopand elements on ZnO. In this work, magnesium (Mg) was doped into ZnO nanorods. Samples were prepared firstly by deposition of undoped ZnO seed layer on indium thin oxide coated glass substrates by ultrasonic spray pyrolysis method and then followed by the growth of ZnO nanorods doped by three different Mg concentrations by hydrothermal method. Based on the morphological, microstructural and optical characterizations results, it is concluded that the increase of magnesium concentration tends to reduce the diameter of ZnO nanorods, increases the bandgap energy and decreases the UV absorption the luminescence in UV and visible range.

Removal and recovery of uranium(VI) by waste digested activated sludge in fed-batch stirred tank reactor.

PubMed

Jain, Rohan; Peräniemi, Sirpa; Jordan, Norbert; Vogel, Manja; Weiss, Stephan; Foerstendorf, Harald; Lakaniemi, Aino-Maija

2018-05-24

This study demonstrated the removal and recovery of uranium(VI) in a fed-batch stirred tank reactor (STR) using waste digested activated sludge (WDAS). The batch adsorption experiments showed that WDAS can adsorb 200 (±9.0) mg of uranium(VI) per g of WDAS. The maximum adsorption of uranium(VI) was achieved even at an acidic initial pH of 2.7 which increased to a pH of 4.0 in the equilibrium state. Desorption of uranium(VI) from WDAS was successfully demonstrated from the release of more than 95% of uranium(VI) using both acidic (0.5 M HCl) and alkaline (1.0 M Na 2 CO 3 ) eluents. Due to the fast kinetics of uranium(VI) adsorption onto WDAS, the fed-batch STR was successfully operated at a mixing time of 15 min. Twelve consecutive uranium(VI) adsorption steps with an average adsorption efficiency of 91.5% required only two desorption steps to elute more than 95% of uranium(VI) from WDAS. Uranium(VI) was shown to interact predominantly with the phosphoryl and carboxyl groups of the WDAS, as revealed by in situ infrared spectroscopy and time-resolved laser-induced fluorescence spectroscopy studies. This study provides a proof-of-concept of the use of fed-batch STR process based on WDAS for the removal and recovery of uranium(VI). Copyright © 2018 Elsevier Ltd. All rights reserved.

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

Pirrung, Georg; Madsen, Helge; Schreck, Scott

Current fast aeroelastic wind turbine codes suitable for certification lack an induction model for standstill conditions. A trailed vorticity model previously used as addition to a blade element momentum theory based aerodynamic model in normal operation has been extended to allow computing the induced velocities in standstill. The model is validated against analytical results for an elliptical wing in constant inflow and against stand still measurements from the NREL/NASA Phase VI unsteady experiment. The extended model obtains good results in case of the elliptical wing, but underpredicts the steady loading for the Phase VI blade in attached flow. The predictionmore » of the dynamic force coefficient loops from the Phase VI experiment is improved by the trailed vorticity modeling in both attached flow and stall in most cases. The exception is the tangential force coefficient in stall, where the codes and measurements deviate and no clear improvement is visible.« less

Phytoremediation of industrial mines wastewater using water hyacinth.

PubMed

Saha, Priyanka; Shinde, Omkar; Sarkar, Supriya

2017-01-02

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

Phytoremediation of industrial mines wastewater using water hyacinth

PubMed Central

Saha, Priyanka; Shinde, Omkar; Sarkar, Supriya

2017-01-01

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

Trailed vorticity modeling for aeroelastic wind turbine simulations in stand still

DOE PAGES

Pirrung, Georg; Madsen, Helge; Schreck, Scott

2016-10-03

Current fast aeroelastic wind turbine codes suitable for certification lack an induction model for standstill conditions. A trailed vorticity model previously used as addition to a blade element momentum theory based aerodynamic model in normal operation has been extended to allow computing the induced velocities in standstill. The model is validated against analytical results for an elliptical wing in constant inflow and against stand still measurements from the NREL/NASA Phase VI unsteady experiment. The extended model obtains good results in case of the elliptical wing, but underpredicts the steady loading for the Phase VI blade in attached flow. The predictionmore » of the dynamic force coefficient loops from the Phase VI experiment is improved by the trailed vorticity modeling in both attached flow and stall in most cases. The exception is the tangential force coefficient in stall, where the codes and measurements deviate and no clear improvement is visible.« less

Atomic oxygen degradation of Intelsat 4-type solar array interconnects: Laboratory investigations

NASA Technical Reports Server (NTRS)

Koontz, S. L.; Cross, J. B.; Hoffbauer, M. A.; Kirkendahl, T. D.

1991-01-01

A Hughes 506 type communication satellite belonging to the Intelsat organization was marooned in low Earth orbit on March 14, 1990, following failure of the Titan third stage to separate properly. The satellite, Intelsat VI, was designed for service in geosynchronous orbit and contains several material configurations which are susceptible to attack by atomic oxygen. Analysis showed the silver foil interconnects in the satellite photovoltaic array to be the key materials issue because the silver is exposed directly to the atomic oxygen ram flux. The results are reported of atomic oxygen degradation testing of Intelsat VI type silver foil interconnects both as virgin material and in a configured solar cell element. Test results indicate that more than 80 pct. of the original thickness of silver in the Intelsat VI solar array interconnects should remain after completion of the proposed Space Shuttle rescue and/or reboost mission.

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

USGS Publications Warehouse

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

2008-01-01

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

A Survey of Metal Lines at High-redshift. I. SDSS Absorption Line Studies—the Methodology and First Search Results for O VI

NASA Astrophysics Data System (ADS)

Frank, S.; Mathur, S.; Pieri, M.; York, D. G.

2010-09-01

We report the results of a systematic search for signatures of metal lines in quasar spectra of the Sloan Digital Sky Survey (SDSS) data release 3 (DR3), focusing on finding intervening absorbers via detection of their O VI doublet. Here, we present the search algorithm and criteria for distinguishing candidates from spurious Lyα forest lines. In addition, we compare our findings with simulations of the Lyα forest in order to estimate the detectability of O VI doublets over various redshift intervals. We have obtained a sample of 1756 O VI doublet candidates with rest-frame equivalent width (EW) >=0.05 Å in 855 active galactic nuclei spectra (out of 3702 objects with redshifts in the accessible range for O VI detection). This sample is further subdivided into three groups according to the likelihood of being real and the potential for follow-up observation of the candidate. The group with the cleanest and most secure candidates is comprised of 145 candidates. Sixty-nine of these reside at a velocity separation >=5000 km s-1 from the QSO and can therefore be classified tentatively as intervening absorbers. Most of these absorbers have not been picked up by earlier, automated QSO absorption line detection algorithms. This sample increases the number of known O VI absorbers at redshifts beyond z abs>= 2.7 substantially.

Isotherm Modelling, Kinetic Study and Optimization of Batch Parameters Using Response Surface Methodology for Effective Removal of Cr(VI) Using Fungal Biomass

PubMed Central

Chidambaram, Ramalingam

2015-01-01

Biosorption is a promising alternative method to replace the existing conventional technique for Cr(VI) removal from the industrial effluent. In the present experimental design, the removal of Cr(VI) from the aqueous solution was studied by Aspergillus niger MSR4 under different environmental conditions in the batch systems. The optimum conditions of biosorption were determined by investigating pH (2.0) and temperature (27°C). The effects of parameters such as biomass dosage (g/L), initial Cr(VI) concentration (mg/L) and contact time (min) on Cr(VI) biosorption were analyzed using a three parameter Box–Behnken design (BBD). The experimental data well fitted to the Langmuir isotherm, in comparison to the other isotherm models tested. The results of the D-R isotherm model suggested that a chemical ion-exchange mechanism was involved in the biosorption process. The biosorption process followed the pseudo-second-order kinetic model, which indicates that the rate limiting step is chemisorption process. Fourier transform infrared (FT-IR) spectroscopic studies revealed the possible involvement of functional groups, such as hydroxyl, carboxyl, amino and carbonyl group in the biosorption process. The thermodynamic parameters for Cr(VI) biosorption were also calculated, and the negative ∆Gº values indicated the spontaneous nature of biosorption process. PMID:25786227

Non-noble metal based electro-catalyst compositions for proton exchange membrane based water electrolysis and methods of making

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

Kumta, Prashant N.; Kadakia, Karan Sandeep; Datta, Moni Kanchan

The invention provides electro-catalyst compositions for an anode electrode of a proton exchange membrane-based water electrolysis system. The compositions include a noble metal component selected from the group consisting of iridium oxide, ruthenium oxide, rhenium oxide and mixtures thereof, and a non-noble metal component selected from the group consisting of tantalum oxide, tin oxide, niobium oxide, titanium oxide, tungsten oxide, molybdenum oxide, yttrium oxide, scandium oxide, cooper oxide, zirconium oxide, nickel oxide and mixtures thereof. Further, the non-noble metal component can include a dopant. The dopant can be at least one element selected from Groups III, V, VI and VIImore » of the Periodic Table. The compositions can be prepared using a surfactant approach or a sol gel approach. Further, the compositions are prepared using noble metal and non-noble metal precursors. Furthermore, a thin film containing the compositions can be deposited onto a substrate to form the anode electrode.« less

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

NASA Astrophysics Data System (ADS)

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.

The WMO RA VI Regional Climate Centre Network - a support to users in Europe

NASA Astrophysics Data System (ADS)

Rösner, S.

2012-04-01

Climate, like weather, has no limits. Therefore the World Meteorological Organization (WMO), a specialized United Nations organization, has established a three-level infrastructure to better serve its member countries. This structure comprises Global Producing Centres for Long-range Forecasts (GPCs), Regional Climate Centres (RCCs) and National Meteorological or Hydrometeorological Services (NMHSs), in most cases representing their countries in WMO governance bodies. The elements of this infrastructure are also part of and contribute to the Global Framework for Climate Services (GFCS) agreed to be established by World Climate Conference 3 (WCC-3) and last year's Sixteenth World Meteorological Congress (WMO Cg-XVI). RCCs are the core element of this infrastructure at the regional level and are being establish in all WMO Regional Associations (RAs), i.e. Africa (RA I); Asia (II); South America (III); North America, Central America and the Caribbean (IV); South-West Pacific (V); Europe (VI). Addressing inter-regional areas of common interest like the Mediterranean or the Polar Regions may require inter-regional RCCs. For each region the RCCs follow a user driven approach with regard to governance and structure as well as products generated for the users in the respective region. However, there are common guidelines all RCCs do have to follow. This is to make sure that services are provided based on best scientific standards, are routinely and reliably generated and made available in an operational mode. These guidelines are being developed within WMO and make use of decade-long experience gained in the business of operational weather forecast. Based on the requirements of the 50 member countries of WMO RA VI it was agreed to establish the WMO RCC as a network of centres of excellence that create regional products including long-range forecasts that support regional and national climate activities, and thereby strengthen the capacity of WMO Members in the region to deliver better climate services to national users. On 1 June 2009 the WMO RA VI Pilot RCC-Network started its pilot phase to demonstrate its capability to provide, on an operational day-to-day basis, the products agreed upon by the member countries of RA VI. On 5 October 2011 the process to become formally designated WMO RA VI RCC-Network was initiated, and it is expected that the designation will happen mid to end 2012. The presentation will describe the global and regional activities related to RCCs and explain in more details the situation in WMO RA VI (Europe).

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

Li, Na; Huang, Rudan, E-mail: huangrd@bit.edu.cn

Six new inorganic–organic hybrids based on rigid triangular N-containing ligands, NaCu{sup I}{sub 2}(tib){sub 4}(H{sub 2}O){sub 4}[H{sub 2}PW{sup V}W{sup VI}{sub 11}O{sub 40}][H{sub 2}PW{sup VI}{sub 12}O{sub 40}]·6H{sub 2}O (1), Cu{sup II}{sub 3}(tib){sub 4}Cl{sub 4}[H{sub 2}PW{sup VI}{sub 12}O{sub 40}]{sub 2}·4H{sub 2}O (2), Co(tib){sub 2}[PW{sup V}{sub 3}W{sup VI}{sub 9}O{sub 38}]·5H{sub 2}O (3), Cu{sup II}{sub 3}(tib){sub 2}[P{sub 2}Mo{sup VI}{sub 5}O{sub 22}(O{sub 2})]·4H{sub 2}O (4), Mn(pytpy){sub 2}Mo{sup VI}{sub 4}O{sub 13} (5) and Co(pytpy){sub 2}Mo{sup VI}{sub 4}O{sub 13} (6) (tib=1,3,5-tris(1-imidazolyl)benzene, pytpy=4’-(4”-pyridyl)2,4’:6’,4”-terpyridine), have been hydrothermally synthesized. Single crystal X-ray diffraction studies revealed that compounds 1–4 display two-dimensional (2D) layered structures, and in compounds 1–3, the adjacent Keggin anionsmore » link with each other by W–O–W covalent interactions to form 1D inorganic chains. Compounds 5–6 are 3D “pillar-layer” frameworks based on bimetal–oxide layers pillared by the pytpy ligands. The compounds have been characterized by elemental analysis, powder X−ray diffraction, X-ray photoelectron spectroscopy and thermo gravimetric analyses. Moreover, the electrochemical and catalytic properties of compound 1 have been investigated as well. - Graphical abstract: Six new inorganic–organic hybrids based on rigid triangular N-containing ligands have been obtained under hydrothermal conditions and characterized by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, and thermogravimetric (TG) analyses. Compounds 1–4 display two-dimensional (2D) layers structure, and in compounds 1–3, the adjacent Keggin anions link with each other by W–O–W covalent interactions to form 1D inorganic Keggin anions chains. Compounds 5–6 are 3D “pillar-layer” frameworks based on bimetal–oxide layers pillared by the pytpy ligands. - Highlights: • MOFs based on POMs have been prepared. • Six new compounds based on rigid triangular N-containing ligands. • The adjacent POMs only share the oxygen atom to form a 1D inorganic Keggin chains.« less

Hexavalent chromium content in stainless steel welding fumes is dependent on the welding process and shield gas type.

PubMed

Keane, Michael; Stone, Samuel; Chen, Bean; Slaven, James; Schwegler-Berry, Diane; Antonini, James

2009-02-01

Occupational exposure to welding fumes is a known health hazard. To isolate elements in stainless steel welding fumes with high potential for adverse health outcomes, fumes were generated using a robotic gas metal arc system, using four shield gases of varying oxygen content. The objective was to measure Cr(VI) concentrations in a broad spectrum of gas metal arc welding processes, and identify processes of exceptionally high or low Cr(VI) content. The gases used were 95% Ar/5% O(2), 98% Ar/2% O(2), 95% Ar/5%CO(2), and 75% He/25% Ar. The welder was operated in axial spray mode (Ar/O(2), Ar/CO(2)), short-circuit (SC) mode (Ar/CO(2) low voltage and He/Ar), and pulsed axial-spray mode (98% Ar/2% O(2)). Results indicate large differences in Cr(VI) in the fumes, with Ar/O(2) (Pulsed)>Ar/O(2)>Ar/CO(2)>Ar/CO(2) (SC)>He/Ar; values were 3000+/-300, 2800+/-85, 2600+/-120, 1400+/-190, and 320+/-290 ppm respectively (means +/- standard errors for 2 runs and 3 replicates per run). Respective rates of Cr(VI) generation were 1.5, 3.2, 4.4, 1.3, and 0.46 microg/min; generation rates were also calculated in terms of microg Cr(VI) per metre of wire used. The generation rates of Cr(VI) increased with increasing O(3) concentrations. Particle size measurements indicated similar distributions, but somewhat higher >0.6 microm fractions for the short-circuit mode samples. Fumes were also sampled into 2 selected size ranges, a microspatter fraction (>or=0.6 microm) and a fine (<0.6 microm) fraction; analysis indicated that Cr(VI) is primarily associated with particles <0.6 microm. The conclusion of the study is that Cr(VI) concentrations vary significantly with welding type and shield gas type, and this presents an opportunity to tailor welding practices to lessen Cr(VI) exposures in workplaces by selecting low Cr(VI)-generating processes. Short-circuit processes generated less Cr(VI) than axial-spray methods, and inert gas shielding gave lower Cr(VI) content than shielding with active gases. A short circuit He/Ar shielded process and a pulsed axial spray Ar/O(2) process were both identified as having substantially lower Cr(VI) generation rates per unit of wire used relative to the other processes studied.

Reduction of Cr(VI) to Cr(III) by green rust - sulphate

NASA Astrophysics Data System (ADS)

Skovbjerg, L.; Stipp, S.

2003-04-01

Chromium is widely used in industrial processes such as leather tanning, electro-plating and as colour pigments. Unfortunately, hexavalent chromium is both toxic and very soluble so it can be a problem for groundwater resources. Given the right redox conditions, however, Cr(VI) can be reduced to trivalent chromium, which is much less soluble and is an essential trace nutrient. Fe(II), an element common in soil and sediments under anaerobic conditions, can serve as a reducing agent for Cr(VI). Green Rust (GR) is a layered Fe(II),Fe(III)-hydroxide with various anions compensating charge in the interlayers. It is very effective in reducing Cr(VI) to Cr(III). GR exists in nature and is thought to be precursor for the formation of Fe(III)-oxides and oxyhydroxides at the redox boundary. It may be that the formation of GR is a key process in the effectiveness of reactive barriers for groundwater remediation that are based on Fe(0). The purpose of this work is to investigate the mechanisms controlling Cr(VI) reduction by Green Rust, to examine the effect of Cr adsorption and incorporation on GR morphology and composition, and to define the role of parameters such as interlayer anion, initial Cr(VI) concentration and time. We are using freshly synthesised material that has not been dried to avoid structural changes that may accompany dehydration and rehydration. X-Ray Diffraction (XRD) is used to characterise mineral structural changes and Atomic Force Microscopy (AFM), to examine changes in morphology as reactions take place. By adjusting the concentration of Cr(VI), we can control the rate of surface change and we can observe the nanoscale particles directly.

Short-term chromium (VI) exposure increases phosphorus uptake by the extraradical mycelium of the arbuscular mycorrhizal fungus Rhizophagus irregularis MUCL 41833.

PubMed

Gil-Cardeza, María Lourdes; Calonne-Salmon, Maryline; Gómez, Elena; Declerck, Stéphane

2017-11-01

Hexavalent chromium is a potent carcinogen, while phosphorus is an essential nutrient. The role of arbuscular mycorrhizal fungi (AMF) in the uptake of P is well known and was also reported, at low levels, for Cr. However, it is unclear whether the uptake of Cr can impact the short-term uptake dynamics of P since both elements have a similar chemical structure and may thus potentially compete with each other during the uptake process. This study investigated the impact of Cr(VI) on short-term P uptake by the AMF Rhizophagus irregularis MUCL 41833 in Medicago truncatula. Bi-compartmented Petri plates were used to spatially separate a root compartment (RC) from a hyphal compartment (HC) using a whole plant in vitro culture system. The HC was supplemented with Cr(VI). Chromium(VI) as well as total Cr and P were monitored during 16 h within the HC and their concentrations determined by the end of the experiment within roots and shoots. Our results indicated that the uptake and translocation of Cr from hyphae to roots was a fast process: roots in which the extraradical mycelium (ERM) was exposed to Cr(VI) accumulated more Cr than roots of which the ERM was not exposed to Cr(VI) or was dead. Our results further confirmed that dead ERM immobilized more Cr than alive ERM. Finally our results demonstrated that the short exposure to Cr(VI) was sufficient to stimulate P uptake by the ERM and that the stimulation process began within the first 4 h of exposure. Copyright © 2017 Elsevier Ltd. All rights reserved.

HST/COS OBSERVATIONS OF GALACTIC HIGH-VELOCITY CLOUDS: FOUR ACTIVE GALACTIC NUCLEUS SIGHT LINES THROUGH COMPLEX C

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

Shull, J. Michael; Stevans, Matthew; Danforth, Charles

2011-10-01

We report ultraviolet spectra of Galactic high-velocity clouds (HVCs) in Complex C, taken by the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), together with new 21 cm spectra from the Green Bank Telescope. The wide spectral coverage and higher signal-to-noise ratio, compared to previous HST spectra, provide better velocity definition of the HVC absorption, additional ionization species (including high ions), and improved abundances in this halo gas. Complex C has a metallicity of 10%-30% solar and a wide range of ions, suggesting dynamical and thermal interactions with hot gas in the Galactic halo. Spectra in the COSmore » medium-resolution G130M (1133-1468 A) and G160M (1383-1796 A) gratings detect ultraviolet absorption lines from eight elements in low-ionization states (O I, N I, C II, S II, Si II, Al II, Fe II, P II) and three elements in intermediate- and high-ionization states (Si III, Si IV, C IV, N V). Our four active galactic nucleus sight lines toward Mrk 817, Mrk 290, Mrk 876, and PG 1259+593 have high-velocity H I and O VI column densities, log N{sub Hi}= 19.39-20.05 and log N{sub Ovi}= 13.58-14.10, with substantial amounts of kinematically associated photoionized gas. The high-ion abundance ratios are consistent with cooling interfaces between photoionized and collisionally ionized gas: N(C IV)/N(O VI) {approx} 0.3-0.5, N(Si IV)/N(O VI) {approx} 0.05-0.11, N(N V)/N(O VI) {approx} 0.07-0.13, and N(Si IV)/N(Si III) {approx}0.2.« less

Gait and functionality of individuals with visual impairment who participate in sports.

PubMed

da Silva, Edson Soares; Fischer, Gabriela; da Rosa, Rodrigo Gomes; Schons, Pedro; Teixeira, Luísa Beatriz Trevisan; Hoogkamer, Wouter; Peyré-Tartaruga, Leonardo Alexandre

2018-05-01

Individuals with visual impairment (VI) have often been observed to walk slower than individuals with unimpaired vision. These observations might be confounded by typical low levels of physical activity and greater sedentary behavior in individuals with VI than the overall population. Here, we compared gait and balance measures between individuals with VI who participate in disability sports, and activity level matched sighted individuals. We assessed static balance, anthropometry, self-selected walking speed, locomotion rehabilitation index, and lower limb muscular endurance; and applied physical activity level and fear of falling questionnaires. Individuals with VI who participate in disability sports, self-selected a similar walking speed (1.29 ± 0.26 m/s) as active sighted individuals (1.39 ± 0.21 m/s). Locomotor rehabilitation index and muscular endurance of lower limbs were also similar between groups. Individuals with VI presented lower static balance (42.0 ± 17.0s) than the sighted control group (45.0 ± 0s) when the controls were tested with their eyes open. However, no difference was found when the controls were tested with their eyes closed (30.3 ± 17.0s). Furthermore, individuals with VI showed a greater fear of falling. In conclusion, individuals with VI who participate in disability sports, as goalball and football, walk with similar self-selected walking speeds as active sighted individuals, but have slightly worse static balance and fear of falling. Copyright © 2018 Elsevier B.V. All rights reserved.

Selenite reduction by the obligate aerobic bacterium Comamonas testosteroni S44 isolated from a metal-contaminated soil

PubMed Central

2014-01-01

Background Selenium (Se) is an essential trace element in most organisms but has to be carefully handled since there is a thin line between beneficial and toxic concentrations. Many bacteria have the ability to reduce selenite (Se(IV)) and (or) selenate (Se(VI)) to red elemental selenium that is less toxic. Results A strictly aerobic bacterium, Comamonas testosteroni S44, previously isolated from metal(loid)-contaminated soil in southern China, reduced Se(IV) to red selenium nanoparticles (SeNPs) with sizes ranging from 100 to 200 nm. Both energy dispersive X-ray Spectroscopy (EDX or EDS) and EDS Elemental Mapping showed no element Se and SeNPs were produced inside cells whereas Se(IV) was reduced to red-colored selenium in the cytoplasmic fraction in presence of NADPH. Tungstate inhibited Se(VI) but not Se(IV) reduction, indicating the Se(IV)-reducing determinant does not contain molybdenum as co-factor. Strain S44 was resistant to multiple heavy and transition metal(loid)s such as Se(IV), As(III), Cu(II), and Cd(II) with minimal inhibitory concentrations (MIC) of 100 mM, 20 mM, 4 mM, and 0.5 mM, respectively. Disruption of iscR encoding a transcriptional regulator negatively impacted cellular growth and subsequent resistance to multiple heavy metal(loid)s. Conclusions C. testosteroni S44 could be very useful for bioremediation in heavy metal(loid) polluted soils due to the ability to both reduce toxic Se(VI) and Se(IV) to non-toxic Se (0) under aerobic conditions and to tolerate multiple heavy and transition metals. IscR appears to be an activator to regulate genes involved in resistance to heavy or transition metal(loid)s but not for genes responsible for Se(IV) reduction. PMID:25098921

Familiarity breeds contempt: combining proximity loggers and GPS reveals female white-tailed deer (Odocoileus virginianus) avoiding close contact with neighbors.

PubMed

Tosa, Marie I; Schauber, Eric M; Nielsen, Clayton K

2015-01-01

Social interactions can influence infectious disease dynamics, particularly for directly transmitted pathogens. Therefore, reliable information on contact frequency within and among groups can better inform disease modeling and management. We compared three methods of assessing contact patterns: (1) space-use overlap (volume of interaction [VI]), (2) direct contact rates measured by simultaneous global positioning system (GPS) locations (<10 m apart), and (3) direct contact rates measured by proximity loggers (PLs; 1-m detection) among female white-tailed deer (Odocoileus virginianus). We calculated the PL∶GPS contact ratios to see whether both devices reveal similar contact patterns and thus predict similar pathogen transmission patterns. Contact rates measured by GPS and PLs were similarly high for two within-group dyads (pairs of deer in the same social groups). Dyads representing separate but neighboring groups (high VI) had PL∶GPS contact ratios near zero, whereas dyads further apart (intermediate VI) had higher PL∶GPS contact ratios. Social networks based on PL contacts showed the fewest connected individuals and lowest mean centrality measures; network metrics were intermediate when based on GPS contacts and greatest when based on VI. Thus, the VI network portrayed animals to be more uniformly and strongly connected than did the PL network. We conclude that simultaneous GPS locations, compared with PLs, substantially underestimate the impact of group membership on direct contact rates of female deer and make networks appear more connected. We also present evidence that deer coming within the general vicinity of each other are less likely to come in close contact if they are in neighboring social groups than deer whose home ranges overlap little if at all. Combined, these results provide evidence that direct transmission of disease agents among female and juvenile white-tailed deer is likely to be constrained both spatially and by social structure, more so than GPS data alone would suggest.

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

PubMed

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 simulate satisfactorily the experimental uranium extraction data and to support the preliminary conclusions about the role of the phosphates present in mineralised urines. These calculations also showed that the phosphate/calcium ratio is a key parameter as far as the efficiency of the uranium (VI) extraction by the calix[6]arene columns is concerned. It predicted that the addition of CaCl2 in mineralised urines would release uranium (VI) from phosphates by forming calcium (II)-phosphate complexes and thus facilitate the uranium (VI) extraction on calix[6]arene columns. These predictions were confirmed experimentally as the addition of 0.1 mol L(-1) CaCl2 to a mineralised urine containing naturally a high concentration of phosphate (typically 0.04 mol L(-1)) significantly increased the percentage of uranium (VI) extraction on the calix[6]arene columns. Copyright © 2015 Elsevier B.V. All rights reserved.

Elemental speciation for chromium in chromium picolinate products

NASA Astrophysics Data System (ADS)

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

1996-12-01

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

Effective treatment of alkaline Cr(VI) contaminated leachate using a novel Pd-bionanocatalyst: Impact of electron donor and aqueous geochemistry

PubMed Central

Watts, Mathew P.; Coker, Victoria S.; Parry, Stephen A.; Thomas, Russell A.P.; Kalin, Robert; Lloyd, Jonathan R.

2015-01-01

Palladium catalysts offer the potential for the effective treatment of a variety of priority reducible pollutants in natural waters. In this study, microbially synthesized magnetite nanoparticles were functionalized with Pd(0), creating a highly reactive, magnetically recoverable, nano-scale catalyst (Pd-BnM). This was then investigated for the treatment of model Cr(VI) contaminated solutions at a range of pH values, and also alkaline Cr(VI) contaminated leachates from chromite ore processing residue (COPR); a contaminant issue of global concern. The sample of COPR used in this study was obtained from a site in Glasgow, UK, where extensive Cr(VI) contamination has been reported. In initial experiments Pd-BnM was supplied with H2 gas or formate as electron donors, and Cr(VI) removal from model synthetic solutions was quantified at various pH values (2–12). Effective removal was noted at neutral to environmentally relevant alkaline (pH 12) pH values, while the use of formate as an electron donor resulted in loss of performance under acidic conditions (pH 2). Reaction kinetics were then assessed with increasing Pd-BnM loading in both model pH 12 Cr(VI) solutions and the COPR leachate. When formate was used as the electron donor for Pd-BnM, to treat COPR leachate, there was significant inhibition of Cr(VI) removal. In contrast, a promotion of reaction rate, was observed when H2 was employed. Upon sustained reaction with model Cr(VI) solutions, in the presence of excess electron donor (formate or H2), appreciable quantities of Cr(VI) were removed before eventual inactivation of the catalyst. Faster onset of inactivation was reported in the COPR leachates, removing 4% and 64% of Cr(VI) observed from model Cr(VI) solutions, when formate and H2 were used as electron donors, respectively. XAS, TEM-EDX and XPS analysis of the catalysts that had been inactivated in the model solution, showed that the surface had an extensive covering of reduced Cr(III), most likely as a CrOOH phase. COPR reacted catalysts recorded a lower abundance of Cr(III) alongside a high abundance of the leachate components Ca and Si, implicating these elements in the faster onset of inactivation. PMID:26146457

Coexistence of a metastable double hcp phase in bcc-fcc structure transition of Te under high pressure

NASA Astrophysics Data System (ADS)

Akahama, Yuichi; Okawa, Naoki; Sugimoto, Toshiyuki; Fujihisa, Hiroshi; Hirao, Naoshisa; Ohishi, Yasuo

2018-02-01

The structural phase transitions of tellurium (Te) are investigated at pressures of up to 330 GPa at 298 K using an X-ray powder diffraction technique. In the experiments, it was found that the high-pressure bcc phase (Te-V) transitioned to the fcc phase (Te-VI) at 99 GPa, although a double hcp phase (dhcp) coexisted with the fcc phase. As the pressure was increased and decreased, the dhcp phase vanished at 255 and 100 GPa, respectively. These results suggest that the dhcp phase is metastable at 298 K and the structure of the highest-pressure phase of Te is fcc. The present results provide important information regarding the high-pressure behavior of group-16 elements.

Isolation and characterization of a uranium(VI)-nitride triple bond

NASA Astrophysics Data System (ADS)

King, David M.; Tuna, Floriana; McInnes, Eric J. L.; McMaster, Jonathan; Lewis, William; Blake, Alexander J.; Liddle, Stephen T.

2013-06-01

The nature and extent of covalency in uranium bonding is still unclear compared with that of transition metals, and there is great interest in studying uranium-ligand multiple bonds. Although U=O and U=NR double bonds (where R is an alkyl group) are well-known analogues to transition-metal oxo and imido complexes, the uranium(VI)-nitride triple bond has long remained a synthetic target in actinide chemistry. Here, we report the preparation of a uranium(VI)-nitride triple bond. We highlight the importance of (1) ancillary ligand design, (2) employing mild redox reactions instead of harsh photochemical methods that decompose transiently formed uranium(VI) nitrides, (3) an electrostatically stabilizing sodium ion during nitride installation, (4) selecting the right sodium sequestering reagent, (5) inner versus outer sphere oxidation and (6) stability with respect to the uranium oxidation state. Computational analyses suggest covalent contributions to U≡N triple bonds that are surprisingly comparable to those of their group 6 transition-metal nitride counterparts.

Index analysis and human health risk model application for evaluating ambient air-heavy metal contamination in Chemical Valley Sarnia.

PubMed

Olawoyin, Richard; Schweitzer, Linda; Zhang, Kuangyuan; Okareh, Oladapo; Slates, Kevin

2018-02-01

The impacts of air emissions as a consequence of industrial activities around communities of human habitation have been extensively reported. This study is the first to assess potential adverse human health effects in the Chemical Valley Sarnia (CVS) area, around the St. Clair River, using health risk models, ecological and pollution indices. Large quantities of particulate matters (PM) are generated from anthropogenic activities, which contain several heavy metals in trace quantities with potentially adverse effects to humans and environmental health. The distribution, and human health impact assessment of trace element concentrations in PM fractions were examined. Elemental concentrations of As, Cd, Cr (VI), Cu, Fe, Mn, Pb, Ni, Zn were determined in the PM size-segregated samples collected from the CVS area between 2014 and 2017. The results showed relatively high concentration of PM <2.5 (87.19±8.1(mgm 3 )) which is approximately 4 times the WHO air quality guidelines. Pb concentration (143.03 ± 46.87ηg/m 3 ) was 3.6 times higher than the air quality standards of NAAQS. Cr (VI) showed moderate to considerable contamination ( C f =4) in the CVS while Cr (VI), Pb, and Ni had enrichment factor E f < 3 (minimal), signifying contributions from anthropogenic activities. Pollution load index (P Li ) value observed was 1.4 indicating human health risk from the PM, especially for the children in the area. The deposition fluxes (DΦ) showed that PM-bound metals could potentially bypass the head airways and cause damages to the tracheobronchial tree, increasing the human health risks of nephroblastomasis development. The main route of entry for the heavy metal bound PM in humans were observed as through ingestion and inhalation. The highest total excess cancer risks observed for children (6.7×10 -4 ) and adult (1.0×10 -4 ) indicating potential cancer effects. The Incremental Lifetime Cancer Risk (ILCR) increased from Pb < Ni < Cd < Cr (VI) < As. Overall, children are more likely to develop carcinogenic and non-carcinogenic health effects from exposures to elemental concentrations of airborne PM in the study area. Copyright © 2017 Elsevier Inc. All rights reserved.

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

USGS Publications Warehouse

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

2011-01-01

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 μg kg−1, representing a minute fraction of total Cr. Chromium(VI) content was typically below detection in surface soils (top 10 cm) where soil organic matter was high, and increased with increasing depth in the soil auger cores as organic matter decreased. Maximum concentrations of Cr(VI) were up to 3 times greater in the deeper drill core samples than the shallow auger cores. Although Cr(VI) in these vadose zone soils and sediments was only a very small fraction of the total solid phase Cr, they are a potentially important source for Cr(VI) to groundwater. Enhanced groundwater recharge through the vadose zone due to irrigation could carry Cr(VI) from the vadose zone to the groundwater and may be the mechanism responsible for the correlation observed between elevated Cr(VI) and NO3- source concentrations in previously published data for valley groundwaters. Incubation of a valley subsoil showed a Cr(VI) production rate of 24 μg kg−1 a−1 suggesting that field Cr(VI) concentrations could be regenerated annually. Increased Cr(VI) production rates in H+-amended soil incubations indicate that soil acidification processes such as nitrification of ammonium in fertilizers could potentially increase the occurrence of geogenic Cr(VI) in groundwater. Thus, despite the natural origin of the Cr, Cr(VI) generation in the Sacramento Valley soils and sediments has the potential to be influenced by human activities.

Identification of responders to inhaled corticosteroids in a chronic obstructive pulmonary disease population using cluster analysis.

PubMed

Hinds, David R; DiSantostefano, Rachael L; Le, Hoa V; Pascoe, Steven

2016-06-01

To identify clusters of patients who may benefit from treatment with an inhaled corticosteroid (ICS)/long-acting β2 agonist (LABA) versus LABA alone, in terms of exacerbation reduction, and to validate previously identified clusters of patients with chronic obstructive pulmonary disease (COPD) (based on diuretic use and reversibility). Post hoc supervised cluster analysis using a modified recursive partitioning algorithm of two 1-year randomised, controlled trials of fluticasone furoate (FF)/vilanterol (VI) versus VI alone, with the primary end points of the annual rate of moderate-to-severe exacerbations. Global. 3255 patients with COPD (intent-to-treat populations) with a history of exacerbations in the past year. FF/VI 50/25 µg, 100/25 µg or 200/25 µg, or VI 25 µg; all one time per day. Mean annual COPD exacerbation rate to identify clusters of patients who benefit from adding an ICS (FF) to VI bronchodilator therapy. Three clusters were identified, including two groups that benefit from FF/VI versus VI: patients with blood eosinophils >2.4% (RR=0.68, 95% CI 0.58 to 0.79), or blood eosinophils ≤2.4% and smoking history ≤46 pack-years, experienced a reduced rate of exacerbations with FF/VI versus VI (RR=0.78, 95% CI 0.63 to 0.96), whereas those with blood eosinophils ≤2.4% and smoking history >46 pack-years were identified as non-responders (RR=1.22, 95% CI 0.94 to 1.58). Clusters of patients previously identified in the fluticasone propionate/salmeterol (SAL) versus SAL trials of similar design were not validated; all clusters of patients tended to benefit from FF/VI versus VI alone irrespective of diuretic use and reversibility. In patients with COPD with a history of exacerbations, those with greater blood eosinophils or a lower smoking history may benefit more from ICS/LABA versus LABA alone as measured by a reduced rate of exacerbations. In terms of eosinophils, this finding is consistent with findings from other studies; however, the validity of the 2.4% cut-off and the impact of smoking history require further investigation. NCT01009463; NCT01017952; Post-results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Thermal Decoating of Aerospace Aluminum Alloys for Aircraft Recycling

NASA Astrophysics Data System (ADS)

Muñiz Lerma, Jose Alberto; Jung, In-Ho; Brochu, Mathieu

2016-06-01

Recycling of aircraft aluminum alloys can be complex due to the presence of their corrosion protection coating that includes inorganic compounds containing Cr(VI). In this study, the characterization and thermal degradation behavior of the coating on aluminum substrates coming from an aircraft destined for recycling are presented. Elements such as Sr, Cr, Si, Ba, Ti, S, C, and O were found in three different layers by EDS elemental mapping corresponding to SrCrO4, Rutile-TiO2, SiO2, and BaSO4 with an overall particle size D 50 = 1.96 µm. The thermal degradation profile analyzed by TGA showed four different stages. The temperature of complete degradation at the fourth stage occurred at 753.15 K (480 °C) at lower heating rates. At higher heating rates and holding an isotherm at the same temperature, the residence time to fully decompose the aircraft coating has been estimated as 4.0 ± 0.2 minutes. The activation energy calculated by the Flynn-Wall-Ozawa and the modified Coats-Redfern methods for multiple fraction of decomposition showed a non-constant behavior indicating the complexity of the reaction. Finally, the concentration of Cr(VI) released to the environment during thermal decoating was obtained by UV-Vis spectroscopy. It was found that 2.6 ± 0.1 µg of Cr(VI)/mm2 of aluminum substrate could be released unless adequate particle controls are used.

Oxidative dissolution of pyrite surfaces by hexavalent chromium: Surface site saturation and surface renewal

NASA Astrophysics Data System (ADS)

Graham, Andrew M.; Bouwer, Edward J.

2012-04-01

In-situ reduction of toxic Cr(VI) to nontoxic Cr(III) represents an important natural attenuation process for Cr(VI)-impacted environments. This study investigates the stoichiometry and kinetics of Cr(VI) reduction by pyrite, a reduced iron-sulfur mineral ubiquitous in recent estuarine and marine sediments. Pyrite suspensions at surface loadings of 0.28-2.10 m2/L (typical of estuarine or marine sediments) were capable of completely reducing 7-120 μM Cr(VI) on the timescale of minutes to days, with the time to reaction completion decreasing with increasing pyrite loading, decreasing initial Cr(VI) concentration, and decreasing suspension pH. Analysis of metal species (Cr and Fe) and sulfur species in solution and at the mineral surface indicated that Cr(VI) oxidatively dissolved the pyrite surface, releasing ferrous iron and sulfate into solution as the reaction progressed. Surface disulfide groups were postulated as the Cr(VI)-reactive surface entity. Net production or consumption of aqueous Fe(II) was shown to depend upon the relative rates of proton-promoted Fe(II) release, Fe(II) release due to oxidative dissolution of pyrite in the presence of Cr(VI), and Fe(II) consumption due to homogeneous reaction with Cr(VI). Kinetics of Cr(VI) reduction by pyrite displayed a biphasic pattern, and the time to reaction completion increased dramatically with increasing initial Cr(VI) concentration. Rapid Cr(VI) removal occurred early in the reaction progress, attributable to Cr(VI) loss under an adsorption-limited regime. Slow, approximately zero-order, Cr(VI) removal occurred over the bulk of the time courses, and corresponded to Cr(VI) removal under surface site saturation conditions. Stoichiometric Cr(VI) reduction was able to proceed under surface site limited conditions owing to regeneration of reactive surface sites following desorption/dissolution of oxidized surface products, as demonstrated in repeat Cr(VI)-spiking experiments. The role of surface passivation was evaluated by comparing rates of Cr(VI) reduction in the presence and absence of the Cr(III)-complexing agent citrate. While citrate addition significantly enhanced Cr(III) solubility, rates of Cr(VI) reduction were only marginally accelerated, suggesting that Cr(OH)3(s) coatings did not completely block access of Cr(VI) to reactive surface sites on pyrite. Given the rapid rates of Cr(VI) reduction with pyrite under pH and surface coverage conditions typical of natural environments, we propose that Cr(VI) reduction by pyrite be considered in fate and transport models for Cr in contaminated sediments.

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.

PubMed

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

2017-01-05

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 2 O 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. Copyright © 2016 Elsevier B.V. All rights reserved.

Elevated tissue Cr levels, increased plasma oxidative markers, and global hypomethylation of blood DNA in male Sprague-Dawley rats exposed to potassium dichromate in drinking water.

PubMed

Wang, Yu; Wu, Wei; Yao, Chunji; Lou, Jianlin; Chen, Riping; Jin, Lingzhi; Wu, Nanxiang; Gao, Ming; Song, Peng; Tan, Yufeng; Liu, Kecheng

2016-09-01

Hexavalent chromium [Cr (VI)] is prevalent in ground water in some areas, but evidence on the toxic effects of Cr (VI) via ingestion through drinking water remains insufficient. The aims of our study were to investigate the toxic effects of Cr (VI) through oral water ingestion on oxidative stress and DNA methylation. Thirty-two Sprague-Dawley rats were randomly divided into four groups, and exposed to porassium dichromate (K2 Cr2 O7 ; 0, 30, 100, and 300 mg/L) in drinking water for 4 weeks. Mean body weight gain, mean water consumption, clinical chemistry determinations, and oxidative stress levels in plasma were measured. Global DNA methylation changes and DNA methylation status at the promoter of p16 gene were also detected. After 4 weeks, mild anemic effects and increased plasma malondialdehyde (MDA) levels occurred in rats exposed to 100 mg/L or 300 mg/L of Cr (VI). Plasma glutathione peroxidase (GSH-Px) activity decreased in all exposed groups. Global DNA methylation levels were reduced in 100 mg/L and 300 mg/L exposure groups. However, DNA methylation status at the promoter of P16 gene remained unchanged in all K2 Cr2 O7- treated groups. The correlation analysis indicated that increased MDA levels were closely correlated to global DNA hypomethylation. Our results indicated that oral ingestion of Cr (VI) through drinking water caused not only oxidative stress in plasma, but also global DNA hypomethylation in blood cells from male rats, and a good correlation was found between increased MDA levels and reduced global DNA methylation. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1080-1090, 2016. © 2015 Wiley Periodicals, Inc.

Effects of visual illusion and transcutaneous electrical nerve stimulation on neuropathic pain in patients with spinal cord injury: A randomised controlled cross-over trial.

PubMed

Özkul, Çağla; Kılınç, Muhammed; Yıldırım, Sibel Aksu; Topçuoğlu, Elif Yalçın; Akyüz, Müfit

2015-01-01

Chronic pain is a common consequence of spinal cord injury (SCI). No therapeutic drugs or drug groups are proven to be superior for neuropathic pain and treatments only aim to convert pain from dull to tolerable levels and not to remove it. This study was planned to compare the effect of visual illusion (VI) and transcutaneous electrical nerve stimulation (TENS) on pain intensity, pain quality and functional capacity in SCI patients with neuropathic pain. Twenty-four patients were included and randomly categorized into two groups. In the first group (n= 12), visual illusion was applied for first two weeks, 1 week wash out period and then TENS was applied for 2 weeks. In second group (n= 12), TENS was applied firstly, 1 week wash out and then %visual illusion VI were applied. Pain severity, pain quality, and functional capacity were assessed with the visual analog scale (VAS), the neuropathic pain scale (NPS), and the brief pain inventory (BPI), respectively. A pre-post-treatment and cross over design was used. Wilcoxon signed-rank tests were used for within group analyses. Mann-Whitney U tests were used for analyses that compared different groups. It was observed that pain intensity decrease immediately after both applications (VI: p= 0.07, TENS: p= 0.08). After TENS application for 2 weeks, it was observed that significant decrease in most (p= 0.04) and less (p= 0.02) pain intensity; while there was no significant decrease in pain intensity after 2 weeks for VI (p> 0.05). When findings of NPS were analyzed, hot (p= 0.047), sharp (p= 0.02), unpleasant (p= 0.03) and deep items (p= 0.047) decreased after VI application. When the results of BPI were detected, they were observed that the negative effect of pain on moving ability (p= 0.04) after visual illusion application and the negative effect of pain on mood (p= 0.03), relationships with others (p= 0.04) and sleep (p= 0.04) after TENS application decreased significantly. TENS and VI therapies can be successfully used in clinical practice as an alternative treatment or as a supportive method separetely or together.

Solid phase extraction of uranium(VI) onto benzoylthiourea-anchored activated carbon.

PubMed

Zhao, Yongsheng; Liu, Chunxia; Feng, Miao; Chen, Zhen; Li, Shuqiong; Tian, Gan; Wang, Li; Huang, Jingbo; Li, Shoujian

2010-04-15

A new solid phase extractant selective for uranium(VI) based on benzoylthiourea anchored to activated carbon was developed via hydroxylation, amidation and reaction with benzoyl isothiocyanate in sequence. Fourier transform infrared spectroscopy and total element analysis proved that benzoylthiourea had been successfully grafted to the surface of the activated carbon, with a loading capacity of 1.2 mmol benzoylthiourea per gram of activated carbon. The parameters that affect the uranium(VI) sorption, such as contact time, solution pH, initial uranium(VI) concentration, adsorbent dose and temperature, have been investigated. Results have been analyzed by Langmuir and Freundlich isotherm; the former was more suitable to describe the sorption process. The maximum sorption capacity (82 mg/g) for uranium(VI) was obtained at experimental conditions. The rate constant for the uranium sorption by the as-synthesized extractant was 0.441 min(-1) from the first order rate equation. Thermodynamic parameters (DeltaH(0)=-46.2 kJ/mol; DeltaS(0)=-98.0 J/mol K; DeltaG(0)=-17.5 kJ/mol) showed the adsorption of an exothermic process and spontaneous nature, respectively. Additional studies indicated that the benzoylthiourea-anchored activated carbon (BT-AC) selectively sorbed uranyl ions in the presence of competing ions, Na(+), Co(2+), Sr(2+), Cs(+) and La(3+). 2009 Elsevier B.V. All rights reserved.

Removal of Cr(VI) from groundwater by Fe(0)

NASA Astrophysics Data System (ADS)

Gao, Yanjiao; Liu, Rui

2017-11-01

This research was conducted to investigate the treatment of hexavalent chromium (Cr(VI)) by iron powder (Fe(0)) columns of simulated permeable reactive barriers with and without calcium carbonate (CaCO3). Two columns filled with Fe(0) were used as Cr(VI) removal equipment running at a flow velocity of 10 ml/min at room temperature. After 200 days running of the two columns, the results showed that Fe(0) was an effective material for Cr(VI) reduction with an average removal rate of above 84.6%. The performance of Column 2 with CaCO3 was better than Column 1 without CaCO3 in terms of average Cr(VI) removal rate. The presence of CaCO3 buffered the increasing pH caused by Fe(0) corrosion in Column 2 and enhanced the removal rate of Column 2. Scanning Electron Microscopy (SEM) images of Fe(0) in the three stages of running of the two columns illustrated that the coat layer of Column 1 was a little thicker than that of Column 2. Energy-dispersive spectrometry (EDS) results showed that the surface of Fe(0) of Column 2 contained more chromium elements. Raman spectroscopy found that all iron oxide was generated on the Fe(0) surface of Column 1 and Column 2 and chromium class objects were only detected on Fe(0) surface in Column 2.

Ferrate(VI) oxidation of polychlorinated diphenyl sulfides: Kinetics, degradation, and oxidized products.

PubMed

Chen, Jing; Xu, Xinxin; Zeng, Xiaolan; Feng, Mingbao; Qu, Ruijuan; Wang, Zunyao; Nesnas, Nasri; Sharma, Virender K

2018-06-13

This paper presents oxidation of polychlorinated diphenyl sulfides (PCDPSs), dioxin-like compounds, by ferrate(VI) (Fe VI O 4 2- , Fe(VI)). Kinetics of the reactions of Fe(VI) with seventeen PCDPSs, differ in number and positions of chlorine atoms (from 2 to 7), were investigated at pH 8.0. The second-order rate constants (k, M -1 s -1 ) of the reactions varied with the numbers and positions of chlorine atoms and appeared to be related with standard Gibbs free energy of formation (Δ f G 0 ) of PCDPSs. Degradation experiments in the presence of ions and humic acid demonstrated complete removal of PeCDPS by Fe(VI) in minutes. Pathways of the reaction were investigated by identifying oxidized products (OPs) of the reaction between Fe(VI) and 2,2',3',4,5-pentachlorodiphenyl sulfide (PeCDPS) at pH 8.0. Pathways of oxidation involved major pathway of attack on sulfur(II) by Fe(VI) in steps to yield sulfoxide type products, and subsequent breakage of C-S bond with the formation of sulfonic acid-containing trichloro compound. Minor pathways were hydroxylation of benzene ring and substitution of chlorine atom with hydroxyl group. Estimation of toxicity of OPs of the oxidation of PeCDPS by Fe(VI) suggested the decreased toxicity from the parent contaminant. Copyright © 2018. Published by Elsevier Ltd.

Enhanced Cr(VI) removal by polyethylenimine- and phosphorus-codoped hierarchical porous carbons.

PubMed

Chen, Shixia; Wang, Jun; Wu, Zeliang; Deng, Qiang; Tu, Wenfeng; Dai, Guiping; Zeng, Zheling; Deng, Shuguang

2018-08-01

The amino- and phosphorus-codoped (N,P-codoped) porous carbons derived from oil-tea shells were facilely fabricated through a combination of phosphoric acid (H 3 PO 4 ) activation and amino (polyethylenimine, PEI) modification method. The as-synthesized carbon adsorbents were systematically characterized and evaluated for Cr(VI) removal in aqueous solutions. The relationship between adsorbent properties and adsorption behaviors was illustrated. Moreover, the influences of contact time, initial Cr(VI) concentration, pH, coexisting anions and temperature were also investigated. The adsorption behavior of Cr(VI) could be perfectly described by the pseudo-second-order kinetic model and Sips adsorption model. The maximum adsorption capacity of Cr(VI) on the carbon adsorbents synthesized in this work was 355.0 mg/g, and this excellent Cr(VI) capacity could be sustained with other coexisting anions. In addition to high surface area and suitable pore size distribution, the high Cr(VI) removal capacity is induced by rich heteroatoms incorporation and the Cr(VI) removal mechanism was clearly illustrated. Furthermore, the continuous column breakthrough experiment on obtained N,P-codoped carbon was conducted and well fitted by the Thomas model. This work revealed that PEI modification and P-containing groups could significantly enhance Cr(VI) adsorption capacity and make these N,P-codoped biomass-derived carbons potent adsorbents in practical water treatment applications. Copyright © 2018 Elsevier Inc. All rights reserved.

Nano Electronics on Atomically Controlled van der Waals Quantum Heterostructures

DTIC Science & Technology

2018-02-19

the group V2-VI3 TI family. However, experimental efforts on Bi2Se3 have been frequently resulted in the bulk conduction being dominant over TSSs in...group V2-VI3 TI family. However, experimental efforts on Bi2Se3 have been frequently resulted in the bulk conduction being dominant over TSSs in...research interest of creating and manipulating unique quasi particles with topologically exceptional properties, such as Majorana particles, has added

Process for forming shaped group II-VI semiconductor nanocrystals, and product formed using process

DOEpatents

Alivisatos, A. Paul; Peng, Xiaogang; Manna, Liberato

2001-01-01

A process for the formation of shaped Group II-VI semiconductor nanocrystals comprises contacting the semiconductor nanocrystal precursors with a liquid media comprising a binary mixture of phosphorus-containing organic surfactants capable of promoting the growth of either spherical semiconductor nanocrystals or rod-like semiconductor nanocrystals, whereby the shape of the semiconductor nanocrystals formed in said binary mixture of surfactants is controlled by adjusting the ratio of the surfactants in the binary mixture.

Value of Free-Run Electromyographic Monitoring of Extraocular Cranial Nerves during Expanded Endonasal Surgery (EES) of the Skull Base.

PubMed

Thirumala, Parthasarathy D; Mohanraj, Santhosh Kumar; Habeych, Miguel; Wichman, Kelley; Chang, Yue-Fang; Gardner, Paul; Snyderman, Carl; Crammond, Donald J; Balzer, Jeffrey

2013-06-01

Objective To evaluate the value of free-run electromyography (f-EMG) monitoring of extraocular cranial nerves (EOCN) III, IV, and VI during expanded endonasal surgery (EES) of the skull base in reducing iatrogenic cranial nerve (CN) deficits. Design We retrospectively identified 200 patients out of 990 who had at least one EOCN monitored during EES. We further separated patients into groups according to the specific CN monitored. In each CN group, we classified patients who had significant (SG) f-EMG activity as Group I and those who did not as Group II. Results A total of 696 EOCNs were monitored. The number of muscles supplied by EOCNs that had SG f-EMG activity was 88, including CN III = 46, CN IV = 21, and CN VI = 21. There were two deficits involving CN VI in patients who had SG f-EMG activity during surgery. There were 14 deficits observed, including CN III = 3, CN IV = 2, and CN VI = 9 in patients who did not have SG f-EMG activity during surgery. Conclusions f-EMG monitoring of EOCN during EES can be useful in identifying the location of the nerve. It seems to have limited value in predicting postoperative neurological deficits. Future studies to evaluate the EMG of EOCN during EES need to be done with both f-EMG and triggered EMG.

Value of Free-Run Electromyographic Monitoring of Extraocular Cranial Nerves during Expanded Endonasal Surgery (EES) of the Skull Base

PubMed Central

Thirumala, Parthasarathy D.; Mohanraj, Santhosh Kumar; Habeych, Miguel; Wichman, Kelley; Chang, Yue-fang; Gardner, Paul; Snyderman, Carl; Crammond, Donald J.; Balzer, Jeffrey

2013-01-01

Objective To evaluate the value of free-run electromyography (f-EMG) monitoring of extraocular cranial nerves (EOCN) III, IV, and VI during expanded endonasal surgery (EES) of the skull base in reducing iatrogenic cranial nerve (CN) deficits. Design We retrospectively identified 200 patients out of 990 who had at least one EOCN monitored during EES. We further separated patients into groups according to the specific CN monitored. In each CN group, we classified patients who had significant (SG) f-EMG activity as Group I and those who did not as Group II. Results A total of 696 EOCNs were monitored. The number of muscles supplied by EOCNs that had SG f-EMG activity was 88, including CN III = 46, CN IV = 21, and CN VI = 21. There were two deficits involving CN VI in patients who had SG f-EMG activity during surgery. There were 14 deficits observed, including CN III = 3, CN IV = 2, and CN VI = 9 in patients who did not have SG f-EMG activity during surgery. Conclusions f-EMG monitoring of EOCN during EES can be useful in identifying the location of the nerve. It seems to have limited value in predicting postoperative neurological deficits. Future studies to evaluate the EMG of EOCN during EES need to be done with both f-EMG and triggered EMG. PMID:23943720

Luteolin inhibits Cr(VI)-induced malignant cell transformation of human lung epithelial cells by targeting ROS mediated multiple cell signaling pathways

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

Pratheeshkumar, Poyil; Son, Young-Ok; Divya, Sasidharan Padmaja

Hexavalent chromium [Cr(VI)] is a well-known human carcinogen associated with the incidence of lung cancer. Inhibition of metal induced carcinogenesis by a dietary antioxidant is a novel approach. Luteolin, a natural dietary flavonoid found in fruits and vegetables, possesses potent antioxidant and anti-inflammatory activity. We found that short term exposure of human bronchial epithelial cells (BEAS-2B) to Cr(VI) (5 μM) showed a drastic increase in ROS generation, NADPH oxidase (NOX) activation, lipid peroxidation, and glutathione depletion, which were significantly inhibited by the treatment with luteolin in a dose dependent manner. Treatment with luteolin decreased AP-1, HIF-1α, COX-2, and iNOS promotermore » activity induced by Cr(VI) in BEAS-2B cells. In addition, luteolin protected BEAS-2B cells from malignant transformation induced by chronic Cr(VI) exposure. Moreover, luteolin also inhibited the production of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α) and VEGF in chronic Cr(VI) exposed BEAS-2B cells. Western blot analysis showed that luteolin inhibited multiple gene products linked to survival (Akt, Fak, Bcl-2, Bcl-xL), inflammation (MAPK, NF-κB, COX-2, STAT-3, iNOS, TNF-α) and angiogenesis (HIF-1α, VEGF, MMP-9) in chronic Cr(VI) exposed BEAS-2B cells. Nude mice injected with BEAS-2B cells chronically exposed to Cr(VI) in the presence of luteolin showed reduced tumor incidence compared to Cr(VI) alone treated group. Overexpression of catalase (CAT) or SOD2, eliminated Cr(VI)-induced malignant transformation. Overall, our results indicate that luteolin protects BEAS-2B cells from Cr(VI)-induced carcinogenesis by scavenging ROS and modulating multiple cell signaling mechanisms that are linked to ROS. Luteolin, therefore, serves as a potential chemopreventive agent against Cr(VI)-induced carcinogenesis. - Highlights: • Luteolin inhibited Cr(VI)-induced oxidative stress. • Luteolin inhibited chronic Cr(VI)-induced malignant transformation. • Luteolin inhibited chronic Cr(VI)-induced inflammation. • Luteolin inhibited chronic Cr(VI)-induced angiogenesis.« less

Salivary carbonic anhydrase VI and its relation to salivary flow rate and buffer capacity in pregnant and non-pregnant women.

PubMed

Kivelä, Jyrki; Laine, Merja; Parkkila, Seppo; Rajaniemi, Hannu

2003-08-01

Previous studies have shown that pregnancy may have unfavourable effects on oral health. The pH and buffer capacity (BC) of paraffin-stimulated saliva, for example, have been found to decrease towards late pregnancy. Salivary carbonic anhydrase VI (CA VI) probably protects the teeth by accelerating the neutralization of hydrogen ions in the enamel pellicle on dental surfaces. Since estrogens and androgens are known to regulate CA expression in some tissues, we studied here whether salivary CA VI concentration shows pregnancy-related changes. Paraffin-stimulated salivary samples were collected from nine pregnant women 1 month before delivery and about 2 months afterwards and assayed for salivary CA VI concentration, BC and flow rate. The enzyme concentration was determined using a specific time-resolved immunofluorometric assay. The control group consisted of 17 healthy non-pregnant women. The results indicated that salivary CA VI levels varied markedly among individuals, but no significant differences in mean concentrations were seen between the samples collected during late pregnancy and postpartum. BC values were lower during pregnancy, however. Our findings suggest that CA VI secretion is not significantly affected by the hormonal alterations associated with pregnancy, and confirm the earlier reports that CA VI is not involved in the regulation of actual salivary BC.

The applications of populus fiber in removal of Cr(VI) from aqueous solution

NASA Astrophysics Data System (ADS)

Li, Miaomiao; Gong, Yumei; Lyu, Aichao; Liu, Yuanfa; Zhang, Hong

2016-10-01

The surface modification of natural materials to be applied in removal of Cr(VI) from aqueous solutions has attracted much attention. A natural sorbent for Cr(VI) based on natural populus fibers (PF) is prepared by transforming the cyano groups (AN) in polyacrylonitriles (PAN) grafted from PF into amidoxime groups (AO), which has strong ability to attract and chelate heavy metal ions. The prepared sorbent is characterized by Fourier Transform Infrared Spectra (FT-IR), thermogravimetric analysis (TGA), solid-state nuclear magnetic resonance (13C NMR) and scanning electron microscope (SEM). As potassium dichromate solution (K2Cr2O7) is used as a target solution for detecting adsorption capacity of the sorbent, the adsorption kinetics of the sorbent for chromiun is consistent with the pseudo-second-order kinetic model by analyzing the adsorption amount as a function of the sorbent dispersed duration in solution at pH = 2. The expected adsorption mechanism is that the Cr(VI) in anionic ions Cr2O72- and HCrO4- are adsorbed through electrostatic attraction but when Cr(VI) is reduced to Cr(III) by AO, the electronegative nitrogen and oxygen in AO chelate it through coordination bond. The as-prepared PF derivant with high adsorption efficiency of chromium 180.5 mg/g (3.47 mmol/g), low cost, reusability and greenly preparation process suggests that the development of natural PF as a sorbent in removal of Cr(VI) from aqueous solutions is a destined significant approach.

A SURVEY OF METAL LINES AT HIGH-REDSHIFT. I. SDSS ABSORPTION LINE STUDIES- THE METHODOLOGY AND FIRST SEARCH RESULTS FOR O VI

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

Frank, S.; Mathur, S.; Pieri, M.

2010-09-15

We report the results of a systematic search for signatures of metal lines in quasar spectra of the Sloan Digital Sky Survey (SDSS) data release 3 (DR3), focusing on finding intervening absorbers via detection of their O VI doublet. Here, we present the search algorithm and criteria for distinguishing candidates from spurious Ly{alpha} forest lines. In addition, we compare our findings with simulations of the Ly{alpha} forest in order to estimate the detectability of O VI doublets over various redshift intervals. We have obtained a sample of 1756 O VI doublet candidates with rest-frame equivalent width (EW) {>=}0.05 A inmore » 855 active galactic nuclei spectra (out of 3702 objects with redshifts in the accessible range for O VI detection). This sample is further subdivided into three groups according to the likelihood of being real and the potential for follow-up observation of the candidate. The group with the cleanest and most secure candidates is comprised of 145 candidates. Sixty-nine of these reside at a velocity separation {>=}5000 km s{sup -1} from the QSO and can therefore be classified tentatively as intervening absorbers. Most of these absorbers have not been picked up by earlier, automated QSO absorption line detection algorithms. This sample increases the number of known O VI absorbers at redshifts beyond z{sub abs{>=}} 2.7 substantially.« less

Adsorption characteristics of hexavalent chromium on HCB/TiO2

NASA Astrophysics Data System (ADS)

Zhang, Li; Zhang, Yonggang

2014-10-01

Sol-gel method was adopted to prepare HCB/TiO2 and its adsorption ability of hexavalent chromium, Cr(VI), and removal from aqueous solution were investigated. The samples were characterized by Power X-ray diffraction (XRD) and a transmission electron microscope (TEM) which showed that the TiO2 was deposited on the surface of HCB. FTIR was used to identify the changes of the surface functional groups before and after adsorption. Potentiometric titration method was used to characterize the zero charge (pHpzc) characteristics of the surface of HCB/TiO2 which showed more acidic functional groups containing. Batch experiments showed that initial pH, absorbent dosage, contact time and initial concentration of Cr(VI) were important parameters for the Cr(VI) adsorption studies. The Freundlich isotherm model better reflected the experimental data better. Cr(VI) adsorption process followed the pseudo-second order kinetic model, which illustrated chemical adsorption. The thermodynamic parameters, such as Gibbs free energy (ΔG), changes in enthalpy change (ΔH) and changes in entropy change (ΔS) were also evaluated. Negative value of free energy occurred at temperature range of 25-45 °C, so Cr(VI) adsorption by HCB/TiO2 is spontaneous. Desorption results showed that the adsorption capacity could maintain 80% after five cycles. The maximum adsorption capacity for Cr(VI) was at 27.33 mg g-1 in an acidic medium, of which the value is worth comparable with other low-cost adsorbents.

GeoChip-based analysis of functional microbial communities in a bioreduced uranium-contaminated aquifer during reoxidation by oxygen

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

Van Nostrand, J.D.; Wu, W.-M.; Wu, L.

2009-07-15

A pilot-scale system was established for in situ biostimulation of U(VI) reduction by ethanol addition at the US Department of Energy's (DOE's) Field Research Center (Oak Ridge, TN). After achieving U(VI) reduction, stability of the bioreduced U(IV) was evaluated under conditions of (i) resting (no ethanol injection), (ii) reoxidation by introducing dissolved oxygen (DO), and (iii) reinjection of ethanol. GeoChip, a functional gene array with probes for N, S and C cycling, metal resistance and contaminant degradation genes, was used for monitoring groundwater microbial communities. High diversity of all major functional groups was observed during all experimental phases. The microbialmore » community was extremely responsive to ethanol, showing a substantial change in community structure with increased gene number and diversity after ethanol injections resumed. While gene numbers showed considerable variations, the relative abundance (i.e. percentage of each gene category) of most gene groups changed little. During the reoxidation period, U(VI) increased, suggesting reoxidation of reduced U(IV). However, when introduction of DO was stopped, U(VI) reduction resumed and returned to pre-reoxidation levels. These findings suggest that the community in this system can be stimulated and that the ability to reduce U(VI) can be maintained by the addition of electron donors. This biostimulation approach may potentially offer an effective means for the bioremediation of U(VI)-contaminated sites.« less

Radiation-induced graft polymerization for the preparation of a highly efficient UHMWPE fibrous adsorbent for Cr(VI) removal

NASA Astrophysics Data System (ADS)

Gao, Qianhong; Hua, Jiangtao; Li, Rong; Xing, Zhe; Pang, Lijuan; Zhang, Mingxing; Xu, Lu; Wu, Guozhong

2017-01-01

A novel fibrous adsorbent containing amine and quaternary ammonium groups was prepared by radiation-induced graft of glycidyl methacrylate (GMA) onto ultra-high molecular weight polyethylene (UHMWPE) fiber and further modifying with triethylenetetramine (TETA) and glycidyl trimethylammonium chloride (GTA). The ATR-IR spectra and SEM observation demonstrated that amine and quaternary ammonium groups were immobilized onto the surface of UHMWPE fiber. The principal factors affecting the adsorption of Cr(VI) ions have been investigated including pH of the aqueous solution, contact time, temperature and coexisting anions. This novel fibrous adsorbent could effectively adsorb Cr(VI) in the range of pH 1-9, and the maximum adsorption capacity reached 295 mg/g at pH 3 and 25 °C based on the Langmuir isotherm. It was found that adsorption equilibrium could be achieved within 2 h for initial Cr(VI) of 100 mg/L, following the pseudo-second order model. The effect of coexisting anions (including SO42-, H2PO4-, NO3-and Cl-) on the uptake of Cr(VI) was investigated in detail. Additionally, the adsorption saturated fiber could be regenerated by soaking in 0.5 mol/L NaOH solution, and the adsorption performance of this adsorbent could be maintained at 90% after eight cycles of adsorption-desorption. ATR-IR and XPS analysis revealed that Cr(VI) ions were adsorbed on the fiber adsorbent through ion exchange mechanism.

Further interest of miniexon multiplex PCR for a rapid typing of Trypanosoma cruzi DTU groups.

PubMed

Aliaga, Claudia; Brenière, Simone Frédérique; Barnabé, Christian

2011-07-01

In order to validate a rapid typing of Trypanosoma cruzi DTUs, the miniexon multiplex PCR was tested for the first time, on a large and diversified sample of 70 strains belonging to all current DTUs (TcI to TcVI). Three DTU groups have been distinguished by specific PCR molecular weight, TcI (200bp), TcII, V, VI (250bp) and TcIII and IV (150bp) with no incorrect grouping. These groups are epidemiologically and genetically relevant; moreover the method is easy and cheap and allows direct identification of parasites from triatomine faeces. Copyright © 2010 Elsevier B.V. All rights reserved.

Combined typhoid fever and hepatitis A vaccine: comparison of immunogenicity and safety to concomitant monovalent vaccine over 3 years.

PubMed

Overbosch, David; Peyron, François; Picot, Nicole; Varichon, Jean-Paul; Dumas, Rafaele; Chambonneau, Laurent; Weber, Françoise

2005-01-01

The safety and immunogenicity of Viatim, a combined hepatitis A (HA) and typhoid fever (Vi) vaccine, were compared with the monovalent component vaccines up to and 1 month after a booster dose at 3 years. Healthy, adult volunteers were randomized to receive Viatim (group A, n = 179) or separate HA and Vi vaccines (group B, n = 181); subgroups were boosted after 3 years with Viatim (groups C and D, n = 56 and 46, respectively). Local and systemic reactions were recorded for 28 days postvaccination. Seroconversion and seroprotection rates and geometric mean antibody concentrations were measured at 14 and 28 days, 1, 2, and 3 years postvaccination, and 28 days after the booster dose. Local and systemic safety profiles were equivalent between the two groups. Immediate local reactions were infrequent (1 in group A and 2 in group B). Local reactions, consisting mostly of mild or moderate pain, were least frequent with monovalent HA. Antibody concentrations to both antigens were similar in groups A and B, in which HA seroprotection rates (> or = 20 mIU/mL) were respectively, 98.7% and 100% at day 28, and 99.1% and 99.0% after 3 years, achieving 100% after the booster. Vi seroprotection rates (> or = 1 microg/mL) of 85.2% and 84.9% after 28 days fell to 32.1% and 35.6% after 3 years, increasing to 67.3% and 69.8% after the booster dose. The combined HA/Vi vaccine, Viatim, had equivalent tolerability and safety and was as rapidly immunogenic as its component monovalent vaccines when given concurrently. A booster dose after 3 years significantly increased antibody levels with some evidence of relative hyporesponsiveness of the typhoid response.

The Effects of Targeted Deliveries of Lovastatin and Tocotrienol on Ossification-Related Gene Expressions in Fracture Healing in an Osteoporosis Rat Model

PubMed Central

Ibrahim, Nurul ‘Izzah; Mohamed, Norazlina; Soelaiman, Ima Nirwana; Shuid, Ahmad Nazrun

2015-01-01

Osteoporotic drugs are used to prevent fragility fractures, but their role in fracture healing still remains unknown. Thus, alternative agents with suitable mode of delivery are needed to promote fracture healing. This study was performed to investigate the effects of direct deliveries of lovastatin and tocotrienol to fracture sites on ossification-related gene expression in fracture healing in a postmenopausal osteoporosis model. Forty-eight Sprague Dawley female rats were divided into six groups. Group I comprised the sham-operated rats, while Groups II–VI were ovariectomized rats. After 8 weeks, the right tibiae of all rats were fractured and stabilized. Group I and Group II were given two single injections of lovastatin and tocotrienol carriers. Group III was given an estrogen preparation at 64.5 µg/kg daily via oral gavages. Group IV was injected with lovastatin particles (750 µg/kg), while Group V was injected with tocotrienol particles (60 mg/kg). Group VI received two single injections of 750 µg/kg lovastatin particles and 60 mg/kg tocotrienol particles. After 4 weeks, the gene expressions were measured. Group VI showed significantly higher gene expressions of osteocalcin, BMP-2, VEGF-α, and RUNX-2 compared to Group II. In conclusion, combined treatment of lovastatin and tocotrienol upregulated the expression of genes related to fracture healing. PMID:26501302

The Effects of Targeted Deliveries of Lovastatin and Tocotrienol on Ossification-Related Gene Expressions in Fracture Healing in an Osteoporosis Rat Model.

PubMed

Ibrahim, Nurul 'Izzah; Mohamed, Norazlina; Soelaiman, Ima Nirwana; Shuid, Ahmad Nazrun

2015-10-16

Osteoporotic drugs are used to prevent fragility fractures, but their role in fracture healing still remains unknown. Thus, alternative agents with suitable mode of delivery are needed to promote fracture healing. This study was performed to investigate the effects of direct deliveries of lovastatin and tocotrienol to fracture sites on ossification-related gene expression in fracture healing in a postmenopausal osteoporosis model. Forty-eight Sprague Dawley female rats were divided into six groups. Group I comprised the sham-operated rats, while Groups II-VI were ovariectomized rats. After 8 weeks, the right tibiae of all rats were fractured and stabilized. Group I and Group II were given two single injections of lovastatin and tocotrienol carriers. Group III was given an estrogen preparation at 64.5 µg/kg daily via oral gavages. Group IV was injected with lovastatin particles (750 µg/kg), while Group V was injected with tocotrienol particles (60 mg/kg). Group VI received two single injections of 750 µg/kg lovastatin particles and 60 mg/kg tocotrienol particles. After 4 weeks, the gene expressions were measured. Group VI showed significantly higher gene expressions of osteocalcin, BMP-2, VEGF-α, and RUNX-2 compared to Group II. In conclusion, combined treatment of lovastatin and tocotrienol upregulated the expression of genes related to fracture healing.

Mechanism of uranium (VI) removal by two anaerobic bacterial communities.

PubMed

Martins, Mónica; Faleiro, Maria Leonor; da Costa, Ana M Rosa; Chaves, Sandra; Tenreiro, Rogério; Matos, António Pedro; Costa, Maria Clara

2010-12-15

The mechanism of uranium (VI) removal by two anaerobic bacterial consortia, recovered from an uncontaminated site (consortium A) and other from an uranium mine (consortium U), was investigated. The highest efficiency of U (VI) removal by both consortia (97%) occurred at room temperature and at pH 7.2. Furthermore, it was found that U (VI) removal by consortium A occurred by enzymatic reduction and bioaccumulation, while the enzymatic process was the only mechanism involved in metal removal by consortium U. FTIR analysis suggested that after U (VI) reduction, U (IV) could be bound to carboxyl, phosphate and amide groups of bacterial cells. Phylogenetic analysis of 16S rRNA showed that community A was mainly composed by bacteria closely related to Sporotalea genus and Rhodocyclaceae family, while community U was mainly composed by bacteria related to Clostridium genus and Rhodocyclaceae family. Copyright © 2010 Elsevier B.V. All rights reserved.

Probing chromium(III) from chromium(VI) in cells by a fluorescent sensor

NASA Astrophysics Data System (ADS)

Hu, Xiangquan; Chai, Jie; Liu, Yanfei; Liu, Bin; Yang, Binsheng

2016-01-01

Cellular uptake of Cr(VI), followed by its reduction to Cr(III) with the formation of kinetically inert Cr(III) complexes, is a complex process. To better understand its physiological and pathological functions, efficient methods for the monitoring of Cr(VI) are desired. In this paper a selective fluorescent probe L, rhodamine hydrazide bearing a benzo[b]furan-2-carboxaldehyde group, was demonstrated as a red chemosensor for Cr(III) at about 586 nm. This probe has been used to probe Cr(III) which is reduced from Cr(VI) by reductants such as glutathione (GSH), vitamin C, cysteine (Cys), H2O2 and Dithiothreitol (DTT) by fluorescence spectra. Cr(VI) metabolism in vivo is primarily driven by Vc and GSH. Vc could reduce CrO42 - to Cr(III) in a faster rate than GSH. The indirectly detection limit for Cr(VI) by L + GSH system was determined to be 0.06 μM at pH = 6.2. Moreover, the confocal microscopy image experiments indicated that Cr(VI) can be reduced to Cr(III) inside cells rapidly and the resulted Cr(III) can be captured and imaged timely by L.

First Detection of Krypton and Xenon in a White Dwarf

NASA Technical Reports Server (NTRS)

Werner, Klaus; Rauch, Thomas; Ringat, Ellen; Kruk, Jeffrey W.

2012-01-01

We report on the first detection of the noble gases krypton (Z = 36) and xenon (54) in a white dwarf. About 20 KrVI-VII and Xe VI-VII lines were discovered in the ultraviolet spectrum of the hot DO-type white dwarf RE 0503-289. The observations, performed with the Far Ultraviolet Spectroscopic Explorer, also reveal highly ionized photospheric lines from other trans-iron group elements, namely Ga (31), Ge (32), As (33), Se (34), Mo (42), Sn (50), Te (52), and I (53), from which gallium and molybdenum are new discoveries in white dwarfs, too. For Kr and Xe, we performed an NLTE analysis and derived mass fractions of log Kr = -4.3 plus or minus 0.5 and log Xe = -4.2 plus or minus 0.6, corresponding to an enrichment by factors of 450 and 3800, respectively, relative to the Sun. The origin of the large overabundances is unclear. We discuss the roles of neutron-capture nucleosynthesis in the-precursor star and radiation-driven diffusion. It is possible that diffusion is insignificant and thaI the observed metal abundances constrain the evolutionary history of the star. Its hydrogen deficiency may be the consequence of a late helium-shell nash or a binary white dwarf merger.

Thermoelectric performance of co-doped SnTe with resonant levels

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

Zhou, Min; Han, Yemao; Li, Laifeng, E-mail: laifengli@mail.ipc.ac.cn, E-mail: wangheng83@gmail.com

2016-07-25

Some group III elements such as Indium are known to produce the resonant impurity states in IV-VI compounds. The discovery of these impurity states has opened up new ways for engineering the thermoelectric properties of IV-VI compounds. In this work, resonant states in SnTe were studied by co-doping with both resonant (In) and extrinsic (Ag, I) dopants. A characteristic nonlinear relationship was observed between the Hall carrier concentration (n{sub H}) and extrinsic dopant concentration (N{sub I}, N{sub Ag}) in the stabilization region, where a linear increase of dopant concentration does not lead to linear response in the measured n{sub H}.more » Upon substituting extrinsic dopants beyond a certain amount, the n{sub H} changed proportionally with additional dopants (Ag, I) (the doping region). The Seebeck coefficients are enhanced as the resonant impurity is introduced, whereas the use of extrinsic doping only induces minor changes. Modest zT enhancements are observed at lower temperatures, which lead to an increase in the average zT values over a broad range of temperatures (300–773 K). The improved average zT obtained through co-doping indicates the promise of fine carrier density control in maximizing the favorable effect of resonant levels for thermoelectric materials.« less

{Mo96La8} eggshell ring and self-assembly to {Mo132} Keplerate through Mo-blue intermediate, involved in UV-photolysis of [Mo7O24](6-)/carboxylic acid system at pH 4.

PubMed

Yamase, Toshihiro; Kumagai, Shun; Prokop, Petra V; Ishikawa, Eri; Tomsa, Adrian-Raul

2010-10-18

The prolonged UV-photolysis of aqueous solutions containing [Mo(7)O(24)](6-) and C(2)H(5)CO(2)H (as electron donor) at pH 3.9-4.1 generates the carboxylate-coordinated {Mo(132)} Keplerate (1a) isolated as a formamidinium/ammonium-mixed salt, [HC(NH(2))(2)](26)(NH(4))(28)[Mo(V)(60)Mo(VI)(72)O(372)(H(2)O)(48)(C(2)H(5)CO(2))(36)((i)C(3)H(7)CO(2))(6)]·16H(2)O (1), through the Mo-blue intermediate (2). The coordination of 2 to La(3+) gives rise to the formation of the chain structure of the C(2)-symmetric {Mo(96)La(8)} eggshell rings, formulated by H(22)[Mo(V)(20)Mo(VI)(76)O(301)(H(2)O)(29){La(H(2)O)(6)}(2)]{La(H(2)O)(5)}(6)]·54.5H(2)O (3). The eggshell-ring geometry results from the insertion of [Mo(VI)(2)O(7)(H(2)O)](2-) (spacer) into the equator outer ring of the wheel-shaped Mo-blue, and 10 {(Mo(VI))(Mo(VI)(5))} pentagonal subunits alternately above and below the equator outer ring are connected by eight La(3+) and two {Mo(VI)(2)} linkers within two inner rings. The neighboring eggshell rings are linked through two Mo-O-Mo bonds formed by dehydrative condensation between the {Mo(VI)(2)} linkers to result in the chain structure. Together with the results of the elemental analysis and IR, electronic absorption, (13)C NMR, and ESI-MS spectra for 2, the ring profile analysis of 3 let us identify 2 with a carbolylate-coordinated Mo-blue ring of high nuclearity. The Mo(VI)→Mo(V) photoreductive change of 2 to the 60-electron reduced Keplerate in the presence of C(2)H(5)CO(2)H involves both degradation of the outer ring and splitting of the binuclear linkers, which leads to the formation of [(Mo(VI))Mo(VI)(5)O(21)(H(2)O)(4)(carboxylate)](7-) pentagonal subunits and [Mo(V)(2)O(4)(carboxylate)](+)/[Mo(V)O(2)(carboxylate)(1/2)](0.5+)-mixed linkers for 1.

42 CFR 441.464 - State assurances.

Code of Federal Regulations, 2010 CFR

2010-10-01

... decision-making about the election of self-direction and provided on a timely basis to an individual or the representative which minimally includes the following: (i) Elements of self-direction compared to non-self... the service plan and service budget. (v) Grievance process. (vi) Risks and responsibilities of self...

Association between plantar fascia vascularity and morphology and foot dysfunction in individuals with chronic plantar fasciitis.

PubMed

Chen, Hongying; Ho, Hok-Ming; Ying, Michael; Fu, Siu Ngor

2013-10-01

Single-cohort laboratory-based study. To identify whether plantar fascia vascularity and thickness are associated with foot pain and dysfunction in individuals with chronic plantar fasciitis. Background Altered plantar fascia vascularity and thickening of the fascia have been identified in individuals with chronic plantar fasciitis. Thirty-eight patients with chronic unilateral plantar fasciitis and 21 controls participated in this study. Proximal plantar fascia vascularization and thickness were assessed using ultrasound imaging, and pain and foot dysfunction were quantified with a visual analog scale and the Chinese version of the Foot Function Index, respectively. Paired t tests were used to assess the side-to-side differences in fascia thickness and vascularity index (VI) in the control and patient groups, and an unpaired t test was used to make comparisons with the patient group. Multiple regression analysis was performed to identify whether the VI and fascia thickness were associated with pain and foot dysfunction. There were significantly higher VI (mean ± SD, 2.4% ± 1.4%) and fascia thickness (5.0 ± 1.3 mm) values in the affected feet when compared with the unaffected feet in the patient group (VI, 1.4% ± 0.5%; fascia thickness, 3.3 ± 0.7 mm) and with the dominant side of the controls (VI, 1.6% ± 0.4%; fascia thickness, 2.9 ± 0.6 mm). After accounting for age, gender, body mass index, and duration of symptoms, the VI explained 13% and 33% of the variance in pain scores measured with a visual analog scale and the pain subscale of the Foot Function Index, respectively; the VI and fascia thickness explained 42% of the variance in the Foot Function Index. Individuals with unilateral chronic plantar fasciitis demonstrated significantly greater vascularity and thickened fascia on the affected side compared to the unaffected side and also to healthy controls. Fascia vascularity was associated independently with self-perceived pain, and both fascia vascularity and thickness were associated with foot dysfunction in patients with chronic plantar fasciitis. Public trials registry: Current Controlled Trials, ISRCTN49594569.

The biomineralization process of uranium(VI) by Saccharomyces cerevisiae - transformation from amorphous U(VI) to crystalline chernikovite.

PubMed

Shen, Yanghao; Zheng, Xinyan; Wang, Xiaoyu; Wang, Tieshan

2018-05-01

Microorganisms play a significant role in uranium(VI) biogeochemistry and influence U(VI) transformation through biomineralization. In the present work, the process of uranium mineralization was investigated by Saccharomyces cerevisiae. The toxicity experiments showed that the viability of cell was not significantly affected by 100 mg L -1 U(VI) under 4 days of exposure time. The batch experiments showed that the phosphate concentration and pH value increased over time during U(VI) adsorption. Meanwhile, thermodynamic calculations demonstrated that the adsorption system was supersaturated with respect to UO 2 HPO 4 . The X-ray powder diffraction spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses indicated that the U(VI) was first attached onto the cell surface and reacted with hydroxyl, carboxyl, and phosphate groups through electrostatic interactions and complexation. As the immobilization of U(VI) transformed it from the ionic to the amorphous state, lamellar uranium precipitate was formed on the cell surface. With the prolongation of time, the amorphous uranium compound disappeared, and there were some crystalline substances observed extracellularly, which were well-characterized as tetragonal-chernikovite. Furthermore, the size of chernikovite was regulated at nano-level by cells, and the perfect crystal was formed finally. These findings provided an understanding of the non-reductive transformation process of U(VI) from the amorphous to crystalline state within microbe systems, which would be beneficial for the U(VI) treatment and reuse of nuclides and heavy metals.

Graduates from vertically integrated curricula.

PubMed

Wijnen-Meijer, Marjo; ten Cate, Olle; van der Schaaf, Marieke; Harendza, Sigrid

2013-06-01

  Vertical integration (VI) has been recommended as an undergraduate medical curriculum structure that fosters the transition to postgraduate training. Our definition of VI includes: (1) the provision of early clinical experience; (2) the integration of biomedical sciences with clinical cases; (3) long clerkships during the final year; and (4) increasing levels of clinical responsibility for students. The aim of the current study is to support the hypothesis that medical graduates from VI programmes meet the expectations of postgraduate supervisors better than those from non-VI curricula.   A questionnaire study was carried out among supervisors of postgraduate training programmes run at Utrecht (the Netherlands, VI; n = 128) and Hamburg (Germany, non-VI; n = 114). The supervisors were asked about their medical graduates' preparedness for work, knowledge and capabilities to manage some specific parts of the work as a doctor. They evaluated their performances on a five-point Likert scale.   The two groups of supervisors did not differ in their judgment of their graduates' preparedness for work and level of knowledge. However, supervisors in Utrecht evaluated their graduates higher with respect to capability to work independently, solving medical problems, managing unfamiliar medical situations, prioritising tasks, collaborating with other people, estimating when they need to consult their supervisors and reflecting on their activities.   Graduates from VI medical curricula appeared to be more capable in several facets of a doctor's job. Research into the actual performance of graduates from VI and non-VI curricula is needed to further support a firm recommendation for VI curricula. © 2013 John Wiley & Sons Ltd.

Osmium (VI) complexes of the 3', 5'-dinucleoside monophosphates, ApU and UpA.

PubMed

Daniel, F B; Behrman, E J

1976-02-10

The dinucleoside monophosphates, ApU and UpA, react with potassium osmate (VI) and 2,2'-bipyridyl to form the corresponding oxo-osmium (VI) bipyridyl sugar ester in which the osmate group is bonded to the terminal 2',3'-glycol. Osmium (VIII) tetroxide and 2,2'-bipyridyl react with the dinucleosides to form the corresponding oxo-osmium (VI) bipyridyl heterocyclic esters which result from addition of the tetroxide to the 5,6-double bond of the uracil residue. Although capable of transesterification reactions, these heterocyclic esters are exceptionally stable toward exchange reactions in solution. No apparent exchange was observed after 1 month. This reaction thus seems promising for single-site osmium labeling in polynucleotides.

Evidence Based Bullying Prevention in Turkey: Implementation of the ViSC Social Competence Program

ERIC Educational Resources Information Center

Dogan, Aysun; Keser, Eda; Sen, Zeynep; Yanagida, Takuya; Gradinger, Petra; Strohmeier, Dagmar

2017-01-01

The ViSC program is the first evidence based anti-bullying program implemented in Turkey. A quasi-experimental longitudinal control group design comprising six schools and 26 classes was realized to examine the program effectiveness regarding different forms of perpetration and victimization. The effectiveness of two dosages of…

Facile synthesis of magnetic Fe3O4/graphene composites for enhanced U(VI) sorption

NASA Astrophysics Data System (ADS)

Zhao, Donglin; Zhu, Hongyu; Wu, Changnian; Feng, Shaojie; Alsaedi, Ahmed; Hayat, Tasawar; Chen, Changlun

2018-06-01

A novel magnetic Fe3O4/graphene composite (FGC) was fabricated by a facile one-step reaction route and shown to be effective for sorbing U(VI) from aqueous solution. The structure, properties and application of the prepared FGC composite were well evaluated. The high saturation magnetization (45.6 emu/g) made FGC easier to be separated from the media within several seconds under an external magnetic. Effects of different ambient conditions (i.e., pH and ionic strength, contact time, temperatures) on sorption behaviors of U(VI) on FGC were carried out by batch experiments. According to the calculation of Langmuir model, the maximum sorption capacity of U(VI) on the FGC at pH 5.5 and 298 K was 176.47 mg/g. The sorption was correlated with the effects of pH, contact time, and temperature. X-ray photoelectron spectroscopy analysis revealed that U(VI) was sorbed on FGC via oxygen-containing functional groups. This work demonstrated that FGC could be recycled and used as an effective recyclable sorbent for sorption of U(VI).

High pressure–low temperature phase diagram of barium: Simplicity versus complexity

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

Desgreniers, Serge; Tse, John S., E-mail: John.Tse@usask.ca; State Key Laboratory of Superhard Materials, Jilin University, 130012 Changchun

2015-11-30

Barium holds a distinctive position among all elements studied upon densification. Indeed, it was the first example shown to violate the long-standing notion that high compression of simple metals should preserve or yield close-packed structures. From modest pressure conditions at room temperature, barium transforms at higher pressures from its simple structures to the extraordinarily complex atomic arrangements of the incommensurate and self-hosting Ba-IV phases. By a detailed mapping of the pressure/temperature structures of barium, we demonstrate the existence of another crystalline arrangement of barium, Ba-VI, at low temperature and high pressure. The simple structure of Ba-VI is unlike that ofmore » complex Ba-IV, the phase encountered in a similar pressure range at room temperature. First-principles calculations predict Ba-VI to be stable at high pressure and superconductive. The results illustrate the complexity of the low temperature-high pressure phase diagram of barium and the significant effect of temperature on structural phase transformations.« less

COUPLED IRON CORROSION AND CHROMATE REDUCTION: MECHANISMS FOR SUBSURFACE REMEDIATION

EPA Science Inventory

The reduction of chromium from the Cr(VI) to the Cr- (Ill) state by the presence of elemental, or zero-oxidation-state, iron metal was studied to evaluate the feasibility of such a process for subsurface chromate remediation. Reactions were studied in systems of natural aquifer m...

42 CFR 431.980 - Eligibility review procedures.

Code of Federal Regulations, 2010 CFR

2010-10-01

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

76 FR 31416 - Federal Acquisition Regulation; Technical Amendments

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-31

... ADMINISTRATION 48 CFR Parts 52 and 53 [FAC 2005-52; Item VI; Docket 2011-0078; Sequence 2] Federal Acquisition... publication schedules. Please cite FAC 2005-52, Technical Amendments. SUPPLEMENTARY INFORMATION: In order to update certain elements in 48 CFR parts 52 and 53, this document makes editorial changes to the Federal...

Le Francais Courant, Part VI: Contemporary French.

ERIC Educational Resources Information Center

Dade County Public Schools, Miami, FL.

This course, developed largely within the framework of units 13, 14, and 15 of the second edition of "A-LM French, Level 2," emphasizes development of basic audiolingual skills. Conversational topics permit the student to review his summer vacation. Principal elements of structure are expressions of quantity, pronouns--including those…

Volumetric determination of uranium titanous sulfate as reductant before oxidimetric titration

USGS Publications Warehouse

Wahlberg, J.S.; Skinner, D.L.; Rader, L.F.

1957-01-01

Need for a more rapid volumetric method for the routine determination of uranium in uranium-rich materials has led to the development of a method that uses titanous sulfate as a reductant before oxidimetric titration. Separation of the hydrogen sulfide group is not necessary. Interfering elements precipitated by cupferron are removed by automatic filtrations made simultaneously rather than by the longer chloroform extraction method. Uranium is reduced from VI to IV by addition of an excess of titanous sulfate solution, cupric ion serving as an indicator by forming red metallic copper when reduction is complete. The copper is reoxidized by addition of mercuric perchlorate. The reduced uranium is then determined by addition of excess ferric sulfate and titration with ceric sulfate. The method has proved to be rapid, accurate, and economical.

Removal of uranium from aqueous solution by a low cost and high-efficient adsorbent

NASA Astrophysics Data System (ADS)

Liu, Yun-Hai; Wang, You-Qun; Zhang, Zhi-Bin; Cao, Xiao-Hong; Nie, Wen-Bin; Li, Qin; Hua, Rong

2013-05-01

In this study, a low-cost and high-efficient carbonaceous adsorbent (HTC-COOH) with carboxylic groups was developed for U(VI) removal from aqueous solution compared with the pristine hydrothermal carbon (HTC). The structure and chemical properties of resultant adsorbents were characterized by Scanning electron microscope (SEM), N2 adsorption-desorption, Fourier transform-infrared spectra (FT-IR) and acid-base titration. The key factors (solution pH, contact time, initial U(VI) concentrations and temperature) affected the adsorption of U(VI) on adsorbents were investigated using batch experiments. The adsorption of U(VI) on HTC and HTC-COOH was pH-dependent, and increased with temperature and initial ion concentration. The adsorption equilibrium of U(VI) on adsorbents was well defined by the Langmuir isothermal equation, and the monolayer adsorption capacity of HTC-COOH was found to be 205.8 mg/g. The kinetics of adsorption was very in accordance with the pseudo-second-order rate model. The adsorption processes of U(VI) on HTC and HTC-COOH were endothermic and spontaneous in nature according to the thermodynamics of adsorption. Furthermore, HTC-COOH could selectively adsorption of U(VI) in aqueous solution containing co-existing ions (Mg2+, Co2+, Ni2+, Zn2+ and Mn2+). From the results of the experiments, it is found that the HTC-COOH is a potential adsorbent for effective removal of U(VI) from polluted water.

Enhanced adsorption of U(VI) and 241Am(III) from wastewater using Ca/Al layered double hydroxide@carbon nanotube composites.

PubMed

Chen, Haijun; Chen, Zhe; Zhao, Guixia; Zhang, Zhibin; Xu, Chao; Liu, Yunhai; Chen, Jing; Zhuang, Li; Haya, Tasawar; Wang, Xiangke

2018-04-05

Ca/Al layered double hydroxide decorated carbon nanotube (Ca/Al-LDH@CNTs) composites were fabricated by co-precipitation method and hydrothermal aged treatment. The prepared Ca/Al-LDH@CNTs was characterized by SEM, TEM, EDS, XRD, FT-IR, UV-vis and XPS techniques, and applied to remove U(VI) from aqueous solutions under various environmental conditions (i.e., pH, ionic strength, temperature and contact time). The results indicated that the adsorption of U(VI) on Ca/Al-LDH@CNTs was four times higher than that of U(VI) on bare CNTs. The kinetic investigations reflected the chemisorption of U(VI) on Ca/Al-LDH@CNTs through oxygen-containing functional groups. The adsorption isotherms demonstrated that the adsorption of U(VI) was well fitted by Langmuir model and the maximum adsorption capacity of U(VI) on Ca/Al-LDH@CNTs was calculated to be 382.9 mg g -1 at 289.15 K. The thermodynamic parameters calculated from temperature-dependent isotherms suggested that U(VI) adsorption on Ca/Al-LDH@CNTs were endothermic and spontaneous process. Furthermore, Ca/Al-LDH@CNTs could remove ∼91% of 241 Am(III) at pH = 8.0, which confirmed Ca/Al-LDH@CNTs as a promising material for multiply low level radionuclides' pollution remediation. Copyright © 2017 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2008-08-01

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

Adverse effects and bioconcentration of chromium in two freshwater rotifer species.

PubMed

Hernández-Ruiz, Esmeralda; Alvarado-Flores, Jesús; Rubio-Franchini, Isidoro; Ventura-Juárez, Javier; Rico-Martínez, Roberto

2016-09-01

Bioaccumulation of trivalent (CrIII) and hexavalent chromium (CrVI), and its adverse effects were studied in two rotifer species: Brachionus calyciflorus (two different strains), and Lecane quadridentata. Median Lethal Concentration (LC50) at 24 h of both species showed that CrVI is highly toxic: LC50 ranges from 4.7 × 10(-5) to 4 × 10(-6) mg L(-1)), compared with CrIII: LC50 ranges from 0.64 to 1.279 mg L(-1). Using the LC50 as an exposure concentration, and using atomic absorption, the bioconcentration factor (BCF) was obtained and BCFs of rotifers exposed to CrIII are four orders of magnitude lower than BCFs of rotifers exposed to CrVI. The effect of Cr on the elemental composition of the two species of rotifers in their structures by X-ray microanalysis by energy dispersion showed that Cr is found in intoxicated rotifers, but not in control rotifers. The basal immunoreactivity to metallothioneins is greater in B. calyciflorus than L. quadridentata. The immunoreactivity to metallothioneins decreases in B. calyciflorus when is exposed to CrIII, in contrast in L. quadridentata the immunoreactivity to metallothioneins increase when is exposed to CrIII, and the immunoreactivity to CrVI in L. quadridentata decrease. A mechanism is proposed in which the harder lorica of L. quadridentata acts as a barrier and accumulator of CrVI, and allows for attenuating responses like metallothionein production in L. quadridentata. Instead, in B. calyciflorus the lack of a harder lorica allows for deeper penetration of CrVI, and no time to produce attenuating measures. Copyright © 2016 Elsevier Ltd. All rights reserved.

The simultaneous detection of trivalent & hexavalent chromium in exhaled breath condensate: A feasibility study comparing workers and controls.

PubMed

Leese, Elizabeth; Morton, Jackie; Gardiner, Philip H E; Carolan, Vikki A

2017-04-01

The analytical method outlined in this feasibility study has been used to show that trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) can be detected and measured in exhaled breath condensate (EBC) samples. EBC samples and urine samples were collected from a cohort of 58 workers occupationally exposed to hexavalent chromium compounds and 22 unexposed volunteers (control group). Levels of Cr(III) and Cr(VI) were determined in EBC samples and total chromium levels were determined in urine samples. Pre and post working week samples for both EBC and urine were collected in tandem. Total chromium in urine samples was analysed by inductively coupled plasma mass spectrometry (ICP-MS). Analysis of Cr(III) and Cr(VI) in EBC samples used a hyphenated micro liquid chromatography (μLC) system coupled to an ICP-MS. Separation was achieved using an anion exchange micro-sized column. The results showed that the occupationally exposed workers had significantly higher levels of Cr(III) and Cr(VI) in their EBC samples than the control group, as well as higher levels of total chromium in their urine samples. However, for the exposed workers no significant difference was found between pre and post working week EBC samples for either Cr(III) or Cr(VI). This study has established that Cr(III) and Cr(VI) can simultaneously be detected and measured in 'real' EBC samples and will help in understanding inhalation exposure. Crown Copyright © 2016. Published by Elsevier GmbH. All rights reserved.

Content of trace elements and chromium speciation in Neem powder and tea infusions.

PubMed

Novotnik, Breda; Zuliani, Tea; Ščančar, Janez; Milačič, Radmila

2015-01-01

Total concentrations of selected trace elements in Neem powder and in Neem tea were determined by inductively coupled plasma mass spectrometry (ICP-MS). The data revealed that despite high total concentrations of the potentially toxic elements Al and Ni in Neem powder, their amounts dissolved in Neem tea were low. Total concentrations of the other toxic elements Pb, As and Cd were also very low and do not represent a health hazard. In contrast, total concentrations of the essential elements Fe, Cu, Zn, Se Mo and Cr in Neem powder were high and also considerable in Neem tea. Consuming one cup of Neem tea (2g per 200 mL of water) covers the recommended daily intakes for Cr and Se and represents an important source of Mo and Cu. Speciation analysis of Cr by high performance liquid chromatography (HPLC) coupled to ICP-MS with the use of enriched Cr isotopic tracers to follow species interconversions during the analytical procedure demonstrated that toxic Cr(VI) was not present either in Neem powder or in Neem tea. Its concentrations were below the limits of detection of the HPLC-ICP-MS procedure applied. The speciation analysis data confirmed that even Cr(VI) was added, it was rapidly reduced by the presence of antioxidants in Neem leaves. By the use of enriched Cr isotopic spike solutions it was also demonstrated that for obtaining reliable analytical data it is essential to apply the extraction procedures which prevent Cr species interconversions, or to correct for species transformation. Copyright © 2015 Elsevier GmbH. All rights reserved.

Embryotoxicity of orally administered chromium in mice: exposure during the period of organogenesis.

PubMed

Junaid, M; Murthy, R C; Saxena, D K

1996-03-01

Administration of chromium (VI)(250, 500 and 750 ppm as potassium dichromate) via drinking water during organogenesis (days 6-14 of gestation) in mice revealed embryo- and fetotoxic effects. Reduced fetal weight, retarded fetal development, number of fetuses (live and dead) per mother and high incidences of dead fetuses and resorptions in treated mothers in the highest dosed group were evident. No significant gross structural abnormalities were observed in any of the fetuses of chromium (VI)-treated mothers. Significant incidences of reduced ossification were found in the highest dosed group. Chromium levels were increased in a dose-dependent manner in maternal blood, placenta and fetuses. The present study suggests a risk to the developing embryo if the mother is exposed to a sufficiently high concentration of chromium (VI) through drinking water during the period of organogenesis.

Timing of Radiation Therapy and Chemotherapy After Breast-Conserving Surgery for Node-Positive Breast Cancer: Long-Term Results From International Breast Cancer Study Group Trials VI and VII

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

Karlsson, Per, E-mail: per.karlsson@oncology.gu.se; Cole, Bernard F.; Price, Karen N.

Purpose: To update the previous report from 2 randomized clinical trials, now with a median follow-up of 16 years, to analyze the effect of radiation therapy timing on local failure and disease-free survival. Patients and Methods: From July 1986 to April 1993, International Breast Cancer Study Group trial VI randomly assigned 1475 pre-/perimenopausal women with node-positive breast cancer to receive 3 or 6 cycles of initial chemotherapy (CT). International Breast Cancer Study Group trial VII randomly assigned 1212 postmenopausal women with node-positive breast cancer to receive tamoxifen for 5 years, or tamoxifen for 5 years with 3 early cycles of initial CT. Formore » patients who received breast-conserving surgery (BCS), radiation therapy (RT) was delayed until initial CT was completed; 4 or 7 months after BCS for trial VI and 2 or 4 months for trial VII. We compared RT timing groups among 433 patients on trial VI and 285 patients on trial VII who received BCS plus RT. Endpoints were local failure, regional/distant failure, and disease-free survival (DFS). Results: Among pre-/perimenopausal patients there were no significant differences in disease-related outcomes. The 15-year DFS was 48.2% in the group allocated 3 months initial CT and 44.9% in the group allocated 6 months initial CT (hazard ratio [HR] 1.12; 95% confidence interval [CI] 0.87-1.45). Among postmenopausal patients, the 15-year DFS was 46.1% in the no-initial-CT group and 43.3% in the group allocated 3 months initial CT (HR 1.11; 95% CI 0.82-1.51). Corresponding HRs for local failures were 0.94 (95% CI 0.61-1.46) in trial VI and 1.51 (95% CI 0.77-2.97) in trial VII. For regional/distant failures, the respective HRs were 1.15 (95% CI 0.80-1.63) and 1.08 (95% CI 0.69-1.68). Conclusions: This study confirms that, after more than 15 years of follow-up, it is reasonable to delay radiation therapy until after the completion of standard CT.« less

Synthesis of backbone P-functionalized imidazol-2-ylidene complexes: en route to novel functional ionic liquids.

PubMed

Majhi, Paresh Kumar; Sauerbrey, Susanne; Schnakenburg, Gregor; Arduengo, Anthony J; Streubel, Rainer

2012-10-01

1-Alkyl-3-methyl-4-diphenylphosphoryl-imidazolium hydrogensulfate (4a,b) (a: R(1) = R(2) = Me; b: R(1) = (i)Pr, R(2) = Me) and 1-alkyl-3-methyl-4,5-bis(diphenylphosphoryl)imidazolium hydrogensulfate (6a,c) (c: R(1) = (n)Bu, R(2) = Me) were obtained selectively and in good yields by oxidative desulfurization of 1-alkyl-3-methyl-4-diphenylphosphino-imidazole-2-thiones (2a,b) and 1-n-butyl-3-methyl-4,5-bis(diphenylphosphoryl)imidazole-2-thione (3c) or 1,3-dimethyl-4-diphenylthiophosphoryl-5-diphenylphosphino-imidazole-2-thione (5a), respectively, with hydrogen peroxide. Synthesis of phosphoryl functionalized imidazol-2-ylidene complexes of group VI metal pentacarbonyls (7a-9a) and (10b-12b) and bis(phosphoryl) functionalized imidazol-2-ylidene complexes of group VI metal pentacarbonyls (13c-15c) and (16a) with low steric demand (methyl, isopropyl, n-butyl) at both N-centers was achieved through deprotonation of imidazolium salts (4a,b) and (6a,c), respectively,-having HSO(4)(-) as a counterion-with potassium tert-butoxide followed by rapid addition of metal pentacarbonyl acetonitrile complexes [M(CO)(5)(CH(3)CN)] (M = Cr, Mo, W). The products were unambiguously characterized by elemental analyses, spectroscopic and spectrometric methods, and in addition, by single-crystal X-ray structure studies in the cases of 4b, 8a, 15c, and 16a; the latter two reveal imidazole ring bond distance alternation in contrast to 8a.

Chemical composition of individual aerosol particles in workplace air during production of manganese alloys.

PubMed

Gunst, S; Weinbruch, S; Wentzel, M; Ortner, H M; Skogstad, A; Hetland, S; Thomassen, Y

2000-02-01

Aerosol particle samples were collected at ELKEM ASA ferromanganese (FeMn) and silicomanganese (SiMn) smelters at Porsgrunn, Norway, during different production steps: raw material mixing, welding of protective steel casings, tapping of FeMn and slag, crane operation moving the ladles with molten metal, operation of the Metal Oxygen Refinement (MOR) reactor and casting of SiMn. Aerosol fractions were assessed for the analysis of the bulk elemental composition as well as for individual particle analysis. The bulk elemental composition was determined by inductively coupled plasma atomic emission spectrometry. For individual particle analysis, an electron microprobe was used in combination with wavelength-dispersive techniques. Most particles show a complex composition and cannot be attributed to a single phase. Therefore, the particles were divided into six groups according to their chemical composition: Group I, particles containing mainly metallic Fe and/or Mn; Group II, slag particles containing mainly Fe and/or Mn oxides; Group III, slag particles consisting predominantly of oxidized flux components such as Si, Al, Mg, Ca, Na and K; Group IV, particles consisting mainly of carbon; Group V, mixtures of particles from Groups II, III and IV; Group VI, mixtures of particles from Groups II and III. In raw material mixing, particles originating from the Mn ores were mostly found. In the welding of steel casings, most particles were assigned to Group II, Mn and Fe oxides. During the tapping of slag and metal, mostly slag particles from Group III were found (oxides of the flux components). During movement of the ladles, most particles came from Group II. At the MOR reactor, most of the particles belonged to the slag phase consisting of the flux components (Group III). The particles collected during the casting of SiMn were mainly attributed to the slag phase (Groups III and V). Due to the compositional complexity of the particles, toxicological investigations on the kinetics of pure compounds may not be easily associated with the results of this study.

Using behavioral statistical physics to understand supply and demand

NASA Astrophysics Data System (ADS)

Farmer, Doyne

2007-03-01

We construct a quantitative theory for a proxy for supply and demand curves using methods that look and feel a lot like physics. Neoclassical economics postulates that supply and demand curves can be explained as the result of rational agents selfishly maximizing their utility, but this approach has had very little empirical success. We take quite a different approach, building supply and demand curves out of impulsive responses to not-quite-random trading fluctuations. Because of reasons of empirical measurability, as a good proxy for changes in supply and demand we study the aggregate price impact function R(V), giving the average logarithmic price change R as a function of the signed trading volume V. (If a trade vi is initiated by a buyer, it has a plus sign, and vice versa for sellers; the signed trading volume for a series of N successive trades is VN(t) = ∑i=t^i=t+N vi). We develop a ``zero-intelligence" null hypothesis that each trade vi gives an impulsive kick f(vi) to the price, so that the average return RN(t) = ∑i=t^i=t+N f(vi). Under the assumption that vi is IID, R(VN) has a characteristic concave shape, becoming linear in the limit as N ->∞. Under some circumstances this is universal for large N, in the sense that it is independent of the functional form of f. While this null hypothesis gives useful qualitative intuition, to make it quantitatively correct, one must add two additional elements: (1) The signs of vi are a long-memory process and (2) the return R is efficient, in the sense that it is not possible to make profits with a linear prediction of the signs of vi. Using data from the London Stock Exchange we demonstrate that this theory works well, predicting both the magnitude and shape of R(VN). We show that the fluctuations in R are very large and for some purposes more important than the average behavior. A computer model for the fluctuations suggests the existence of an equation of state relating the diffusion rate of prices to the flow of trading orders.

Chromium immobilization by extra- and intraradical fungal structures of arbuscular mycorrhizal symbioses.

PubMed

Wu, Songlin; Zhang, Xin; Sun, Yuqing; Wu, Zhaoxiang; Li, Tao; Hu, Yajun; Lv, Jitao; Li, Gang; Zhang, Zhensong; Zhang, Jing; Zheng, Lirong; Zhen, Xiangjun; Chen, Baodong

2016-10-05

Arbuscular mycorrhizal (AM) fungi can enhance plant Cr tolerance through immobilizing Cr in mycorrhizal roots. However, the detailed processes and mechanisms are unclear. The present study focused on cellular distribution and speciation of Cr in both extraradical mycelium (ERM) and mycorrhizal roots exposed to Cr(VI) by using field emission scanning electron microscopy equipped with energy dispersive X-ray spectrometer (FE-SEM-EDS), scanning transmission soft X-ray microscopy (STXM) and X-ray absorption fine structure (XAFS) spectroscopy techniques. We found that amounts of particles (possibly extracellular polymeric substances, EPS) were produced on the AM fungal surface upon Cr(VI) stress, which contributed greatly to Cr(VI) reduction and immobilization. With EDS of the surface of AM fungi exposed to various Cr(VI) levels, a positive correlation between Cr and P was revealed, suggesting that phosphate groups might act as counter ions of Cr(III), which was also confirmed by the XAFS analysis. Besides, STXM and XAFS analyses showed that Cr(VI) was reduced to Cr(III) in AM fungal structures (arbuscules, intraradical mycelium, etc.) and cell walls in mycorrhizal roots, and complexed possibly with carboxyl groups or histidine analogues. The present work provided evidence of Cr immobilization on fungal surface and in fungal structures in mycorrhizal roots at a cellular level, and thus unraveled the underlying mechanisms by which AM symbiosis immobilize Cr. Copyright © 2016 Elsevier B.V. All rights reserved.

Ulex europaeus agglutinin-I binding to dental primary afferent projections in the spinal trigeminal complex combined with double immunolabeling of substance P and GABA elements using peroxidase and colloidal gold.

PubMed

Matthews, M A; Hoffmann, K D; Hernandez, T V

1989-01-01

Ulex europaeus agglutinin I (UEA-I) is a plant lectin with an affinity for L-fucosyl residues in the chains of lactoseries oligosaccharides associated with medium- and smaller-diameter dorsal root ganglion neurons and their axonal processes. These enter Lissauer's tract and terminate within the superficial laminae of the spinal cord overlapping projections known to have a nociceptive function. This implies that the surface coatings of neuronal membranes may have a relationship with functional modalities. The present investigation further examined this concept by studying a neuronal projection with a nociceptive function to determine whether fucosyl-lactoseries residues were incorporated in its primary afferent terminals. Transganglionic transport of horseradish peroxidase (HRP) following injection into tooth pulp chambers was employed to demonstrate dental pulp terminals in the trigeminal spinal complex, while peroxidase and fluorescent tags were used concomitantly to stain for UEA-I. Double immunolabeling for substance P (SP) and gamma-aminobutyric acid (GABA) using peroxidase and colloidal gold allowed a comparison of the distribution of a known excitatory nociceptive transmitter with that of UEA-I binding in specific subnuclei. Synaptic interrelationships between UEA-I positive dental pulp primary afferent inputs and specific inhibitory terminals were also examined. SP immunoreactivity occurred in laminae I and outer lamina II (IIo) of subnucleus caudalis (Vc) and in the ventrolateral and lateral marginal region of the caudal half of subnucleus interpolaris (Vi), including the periobex area in which Vi is slightly overlapped on its lateral aspect by cellular elements of Vc. The adjacent interstitial nucleus (IN) also showed an intense immunoreactivity for this peptide antibody. UEA-I binding displayed a similar distribution pattern in both Vc and Vi, but extended into lamina IIi and the superficial part of Lamina III in Vc. Dental pulp terminals were found to have a comparable distribution; however, many extended into the dorsal portion of the caudal half of Vi and the ventromedial quadrant of rostral Vi. Electron-microscopic analysis showed that transganglionically labeled dental pulp terminals contained ovoid, complex membrane-bound vacuoles laden with transported HRP. The preterminal axon and synaptic membranes of those dental pulp terminals located in zones of Vc and Vi displaying an affinity for UEA-I were usually characterized by a patchy, electron-dense coating of the peroxidase tag. SP was demonstrated ultrastructurally with Protein-A colloidal gold (3-nm particles), whereas GABA immunoreactivity was revealed by the avidin-biotin-peroxidase method.(ABSTRACT TRUNCATED AT 400 WORDS)

Commander, U.S. Pacific Fleet

Science.gov Websites

Us SAN DIEGO (May 22, 2018) Sailors assigned to Coastal Riverine Squadron (CRS) 3 operate a Mark VI patrol boat during a final evaluation problem conducted by Coastal Riverine Group (CRG) 1's training and ./Released) Sailors assigned to Coastal Riverine Squadron 3 operate a Mark VI patrol boat in waters off San

Prevention of Cyberbullying and Cyber Victimization: Evaluation of the ViSC Social Competence Program

ERIC Educational Resources Information Center

Gradinger, Petra; Yanagida, Takuya; Strohmeier, Dagmar; Spiel, Christiane

2015-01-01

It is well-documented that cyberbullying and victimization co-occur with traditional forms indicating that they share similar mechanisms. Therefore, it was hypothesized that the general antibullying program ViSC might also be effective in tackling these new forms of bullying. A longitudinal randomized control group design has been applied to…

Region VI Inservice Training for Vocational-Technical Personnel (Arlington, Texas, October 7-10, 1975). Conference Report.

ERIC Educational Resources Information Center

EPD Consortium D, Richardson, TX.

This conference report contains a collection of thirteen papers delivered at the Region VI (New Mexico, Texas, Mississippi, Louisiana, and Oklahoma) inservice training conference, which focused on special needs groups (i.e., those with academic, socioeconomic, or physical handicaps that prevent them from succeeding in regular vocational programs).…

Effects of combination therapy with vildagliptin and valsartan in a mouse model of type 2 diabetes

PubMed Central

2013-01-01

Background Dipeptidyl peptidase-4 (DPP-4) inhibitors modulate incretin hormones and exert anti-diabetic effects in type 2 diabetes mellitus. Treatment with angiotensin II type 1 receptor blockers (ARB) is a proven successful intervention for hypertension with type 2 diabetes. The present study investigated the combined effects of the DPP-4 inhibitor vildagliptin and the ARB valsartan in a mouse model of type 2 diabetes. Methods C57BL/6 J mice fed with high-fat diet (HFD) or db/db mice were treated with placebo, phloridzin (PHZ), vildagliptin alone (ViL), valsartan alone (VaL) or ViL with VaL (ViLVaL) for 8 weeks. Results Glucose metabolism was improved in response to PHZ, ViL and ViLVaL in both HFD and db/db mice. Upon glucose challenge, ViLVaL showed the greatest suppression of blood glucose excursions, with increased insulin secretion, in db/db mice. ViLVaL treatment also showed an improvement of insulin sensitivity in db/db mice. Serum inflammatory cytokines were significantly decreased, and adiponectin was highest, in the ViLVaL group. ViLVaL improved insulin signaling and attenuated stress signaling in liver with amelioration of hepatic steatosis due to activated fatty acid oxidation in db/db mice. Furthermore, immunohistochemical analysis of the pancreas revealed that the combination treatment resulted in an increased expression of insulin and PDX-1, and increased insulin content. Conclusions The combination therapy of ViL and VaL improves both pancreatic beta-cell function and insulin sensitivity, with a reduction of the inflammatory and cell stress milieu in mouse models of T2DM. Our results suggest that this combination therapy exerts additive or even synergistic benefits to treat T2DM. PMID:24188631

Effects of the CO II laser combined with fluoridated toothpaste on human dental enamel demineralization

NASA Astrophysics Data System (ADS)

Azevedo Rodrigues, Lidiany Karla; Alvarez Vidigal, Evelyn; Silva Soares, Luís Eduardo; Abrahão Martin, Airton; Brugnera-Júnior, Aldo; Aparecida Zanin, Fátima Antonia; Nobre dos Santos, Marinês

2006-02-01

This in vitro pilot study investigated the CO II laser effects on demineralization inhibition in sound human dental enamel. Thirty six human enamel specimens were used and randomly assigned to 6 groups, as follows: I) Control; II) 1W; III) 2W; IV) 3W; V) 4W; VI) 5W. Group I one was kept as control and others were irradiated using a pulsed CO II laser (λ=10.6 μm) with low crescent potencies. Fourier Transform Raman Spectroscopy was used to study the surface composition of specimens after irradiation. One specimen from each group was analyzed by Scanning Electron Microscopy and the remaining ones were submitted to an 8-day pH cycling model with use of fluoridated toothpaste twice a day. After pH-cycling, the cross-sectional microhardness was performed for mineral loss (ΔZ) quantification. The data were analyzed by ANOVA and Tuckey test (α=0.05). No changes were found either in SEM photomicrographies or RAMAN Spectra of the specimens in all groups. The ΔZ values (n=5; mean+/-SD) for I-VI groups were: 1741.6+/-725.3a 1782.7+/-639.0a 1427.2+/-237.0a 1780.6+/-552.4a 1385.2+/-602.2a 943.1+/-228.1a respectively. The highest percentage of caries inhibition was found in group VI (45.8%); however the differences between ΔZ of the groups were not statistically significant. The use of CO II laser with low fluencies did not prevent more caries development than the use of fluoridated toothpaste, even though group VI had present good results in caries inhibition. Energy densities higher than 0.0125 J/cm 2 should be used to promote chemical or morphological changes on enamel surface, which are able of inhibiting mineral.

Comparative Genomics of Plant-Associated Pseudomonas spp.: Insights into Diversity and Inheritance of Traits Involved in Multitrophic Interactions

PubMed Central

Loper, Joyce E.; Hassan, Karl A.; Mavrodi, Dmitri V.; Davis, Edward W.; Lim, Chee Kent; Shaffer, Brenda T.; Elbourne, Liam D. H.; Stockwell, Virginia O.; Hartney, Sierra L.; Breakwell, Katy; Henkels, Marcella D.; Tetu, Sasha G.; Rangel, Lorena I.; Kidarsa, Teresa A.; Wilson, Neil L.; van de Mortel, Judith E.; Song, Chunxu; Blumhagen, Rachel; Radune, Diana; Hostetler, Jessica B.; Brinkac, Lauren M.; Durkin, A. Scott; Kluepfel, Daniel A.; Wechter, W. Patrick; Anderson, Anne J.; Kim, Young Cheol; Pierson, Leland S.; Pierson, Elizabeth A.; Lindow, Steven E.; Kobayashi, Donald Y.; Raaijmakers, Jos M.; Weller, David M.; Thomashow, Linda S.; Allen, Andrew E.; Paulsen, Ian T.

2012-01-01

We provide here a comparative genome analysis of ten strains within the Pseudomonas fluorescens group including seven new genomic sequences. These strains exhibit a diverse spectrum of traits involved in biological control and other multitrophic interactions with plants, microbes, and insects. Multilocus sequence analysis placed the strains in three sub-clades, which was reinforced by high levels of synteny, size of core genomes, and relatedness of orthologous genes between strains within a sub-clade. The heterogeneity of the P. fluorescens group was reflected in the large size of its pan-genome, which makes up approximately 54% of the pan-genome of the genus as a whole, and a core genome representing only 45–52% of the genome of any individual strain. We discovered genes for traits that were not known previously in the strains, including genes for the biosynthesis of the siderophores achromobactin and pseudomonine and the antibiotic 2-hexyl-5-propyl-alkylresorcinol; novel bacteriocins; type II, III, and VI secretion systems; and insect toxins. Certain gene clusters, such as those for two type III secretion systems, are present only in specific sub-clades, suggesting vertical inheritance. Almost all of the genes associated with multitrophic interactions map to genomic regions present in only a subset of the strains or unique to a specific strain. To explore the evolutionary origin of these genes, we mapped their distributions relative to the locations of mobile genetic elements and repetitive extragenic palindromic (REP) elements in each genome. The mobile genetic elements and many strain-specific genes fall into regions devoid of REP elements (i.e., REP deserts) and regions displaying atypical tri-nucleotide composition, possibly indicating relatively recent acquisition of these loci. Collectively, the results of this study highlight the enormous heterogeneity of the P. fluorescens group and the importance of the variable genome in tailoring individual strains to their specific lifestyles and functional repertoire. PMID:22792073

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

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

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

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

NASA Astrophysics Data System (ADS)

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

2014-04-01

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

Modeling the impact of soil aggregate size on selenium immobilization

NASA Astrophysics Data System (ADS)

Kausch, M. F.; Pallud, C. E.

2013-03-01

Soil aggregates are mm- to cm-sized microporous structures separated by macropores. Whereas fast advective transport prevails in macropores, advection is inhibited by the low permeability of intra-aggregate micropores. This can lead to mass transfer limitations and the formation of aggregate scale concentration gradients affecting the distribution and transport of redox sensitive elements. Selenium (Se) mobilized through irrigation of seleniferous soils has emerged as a major aquatic contaminant. In the absence of oxygen, the bioavailable oxyanions selenate, Se(VI), and selenite, Se(IV), can be microbially reduced to solid, elemental Se, Se(0), and anoxic microzones within soil aggregates are thought to promote this process in otherwise well-aerated soils. To evaluate the impact of soil aggregate size on selenium retention, we developed a dynamic 2-D reactive transport model of selenium cycling in a single idealized aggregate surrounded by a macropore. The model was developed based on flow-through-reactor experiments involving artificial soil aggregates (diameter: 2.5 cm) made of sand and containing Enterobacter cloacae SLD1a-1 that reduces Se(VI) via Se(IV) to Se(0). Aggregates were surrounded by a constant flow providing Se(VI) and pyruvate under oxic or anoxic conditions. In the model, reactions were implemented with double-Monod rate equations coupled to the transport of pyruvate, O2, and Se species. The spatial and temporal dynamics of the model were validated with data from experiments, and predictive simulations were performed covering aggregate sizes 1-2.5 cm in diameter. Simulations predict that selenium retention scales with aggregate size. Depending on O2, Se(VI), and pyruvate concentrations, selenium retention was 4-23 times higher in 2.5 cm aggregates compared to 1 cm aggregates. Under oxic conditions, aggregate size and pyruvate concentrations were found to have a positive synergistic effect on selenium retention. Promoting soil aggregation on seleniferous agricultural soils, through organic matter amendments and conservation tillage, may thus help decrease the impacts of selenium contaminated drainage water on downstream aquatic ecosystems.

Modeling the impact of soil aggregate size on selenium immobilization

NASA Astrophysics Data System (ADS)

Kausch, M. F.; Pallud, C. E.

2012-09-01

Soil aggregates are mm- to cm-sized microporous structures separated by macropores. Whereas fast advective transport prevails in macropores, advection is inhibited by the low permeability of intra-aggregate micropores. This can lead to mass transfer limitations and the formation of aggregate-scale concentration gradients affecting the distribution and transport of redox sensitive elements. Selenium (Se) mobilized through irrigation of seleniferous soils has emerged as a major aquatic contaminant. In the absence of oxygen, the bioavailable oxyanions selenate, Se(VI), and selenite, Se(IV), can be microbially reduced to solid, elemental Se, Se(0), and anoxic microzones within soil aggregates are thought to promote this process in otherwise well aerated soils. To evaluate the impact of soil aggregate size on selenium retention, we developed a dynamic 2-D reactive transport model of selenium cycling in a single idealized aggregate surrounded by a macropore. The model was developed based on flow-through-reactor experiments involving artificial soil aggregates (diameter: 2.5 cm) made of sand and containing Enterobacter cloacae SLD1a-1 that reduces Se(VI) via Se(IV) to Se(0). Aggregates were surrounded by a constant flow providing Se(VI) and pyruvate under oxic or anoxic conditions. In the model, reactions were implemented with double-Monod rate equations coupled to the transport of pyruvate, O2, and Se-species. The spatial and temporal dynamics of the model were validated with data from experiments and predictive simulations were performed covering aggregate sizes between 1 and 2.5 cm diameter. Simulations predict that selenium retention scales with aggregate size. Depending on O2, Se(VI), and pyruvate concentrations, selenium retention was 4-23 times higher in 2.5-cm-aggregates compared to 1-cm-aggregates. Under oxic conditions, aggregate size and pyruvate-concentrations were found to have a positive synergistic effect on selenium retention. Promoting soil aggregation on seleniferous agricultural soils, through organic matter amendments and conservation tillage, may thus help decrease the impacts of selenium contaminated drainage water on downstream aquatic ecosystems.

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

PubMed

Milačič, Radmila; Zuliani, Tea; Ščančar, Janez

2012-06-01

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

Selenium speciation and partitioning within Burkholderia cepacia biofilms formed on α-Al 2O 3 surfaces

NASA Astrophysics Data System (ADS)

Templeton, Alexis S.; Trainor, Thomas P.; Spormann, Alfred M.; Brown, Gordon E.

2003-10-01

The distribution and speciation of Se within aerobic Burkholderia cepacia biofilms formed on α-Al 2O 3 (1-102) surfaces have been examined using grazing-angle X-ray spectroscopic techniques. We present quantitative information on the partitioning of 10 -6 M to 10 -3 M selenate and selenite between the biofilms and underlying alumina surfaces derived from long-period X-ray standing wave (XSW) data. Changes in the Se partitioning behavior over time are correlated with microbially induced reduction of Se(VI) and Se(IV) to Se(0), as observed from X-ray absorption near edge structure (XANES) spectroscopy. Selenite preferentially binds to the alumina surfaces, particularly at low [Se], and is increasingly partitioned into the biofilms at higher [Se]. When B. cepacia is metabolically active, B. cepacia rapidly reduces a fraction of the SeO 32- to red elemental Se(0). In contrast, selenate is preferentially partitioned into the B. cepacia biofilms at all [Se] tested due to a lower affinity for binding to the alumina surface. Rapid reduction of SeO 42- by B. cepacia to Se(IV) and Se(0) subsequently results in a vertical segregation of Se species at the B. cepacia/α-Al 2O 3 interface. Elemental Se(0) accumulates within the biofilm with Se(VI), whereas Se(IV) intermediates preferentially sorb to the alumina surface. B. cepacia/α-Al 2O 3 samples incubated with SeO 42- and SeO 32- when the bacteria were metabolically active result in a significant reduction in the mobility of Se vs. X-ray treated biofilms. Remobilization experiments show that a large fraction of the insoluble Se(0) produced within the biofilm is retained during exchange with Se-free solutions. In addition, Se(IV) intermediates generated during Se(VI) reduction are preferentially bound to the alumina surface and do not fully desorb. In contrast, Se(VI) is rapidly and extensively remobilized.

AL(0) in municipal waste incinerator ash

NASA Astrophysics Data System (ADS)

Stipp, S. L.; Ronsbo, J. G.; Zunic, T. B.; Christensen, T. H.

2003-04-01

Disposal of municipal waste is a challenge to society. Waste volume is substantially decreased by incineration but residual ash usually contains a number of toxic components which must be immobilised to insure environmental protection. One element, chromium, is mobile and toxic in its oxidised state as Cr(VI) but it can be reduced to Cr(III) and immobilised. Reduction can be promoted by ash treatment with Fe(0) or Fe(II), but recent evidence shows that at least some Cr(VI) is reduced spontaneously in the ash. Aspects of ash behaviour suggest metallic aluminium as the reducing agent, but no direct evidence of Al(0) has been found until now. We examined filter ash from an energy-producing, municipal-waste incinerator (Vest-forbrænding) near Copenhagen. X-ray diffraction (XRD) identified expected salts of Na, K and Ca such as halite, sylvite, calcite, anhydrite and gypsum as well as quartz, feldspar and some hematite. Wave-dispersive electron microprobe produced elemen-tal maps of the ash; Al-rich areas were analysed quantitatively by comparison with standards. We identified metallic Al particles, averaging 50 to 100 micrometers in di-ameter, often with a fractured, glassy border of aluminum oxide. The particles were porous, explaining fast Cr(VI) reduction and they contained thin exsolution lamellae of Al-alloys of Pb and Cu or Mn, Fe and Ag, which provide clues of the Al(0) origin in the waste. Sometimes Al(0) occurred inside glassy globes of Al2O3. Time-of-flight secondary ion mass spectroscopy (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) proved that surface Al concentrations on ash particles were below detection, confirming reactivity of the Al(0) bulk. The persistence of reduced Al through the highly oxidising combustion procedure comes as a surprise and is a benefit in the immobilisation of Cr(VI) from municipal-waste incineration residues.

Method of passivating semiconductor surfaces

DOEpatents

Wanlass, M.W.

1990-06-19

A method is described for passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

Method of passivating semiconductor surfaces

DOEpatents

Wanlass, Mark W.

1990-01-01

A method of passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

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

PubMed

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

2009-10-30

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

Effect of knee joint angle on neuromuscular activation of the vastus intermedius muscle during isometric contraction.

PubMed

Watanabe, K; Akima, H

2011-12-01

The purpose of this study was to compare the relationship between surface electromyography (EMG) and knee joint angle of the vastus intermedius muscle (VI) with the synergistic muscles in the quadriceps femoris (QF) muscle group. Fourteen healthy men performed maximal voluntary contractions during isometric knee extension at four knee joint angles from 90°, 115°, 140°, and 165° (180° being full extension). During the contractions, surface EMG was recorded at four muscle components of the QF muscle group: the VI, vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) muscles. The root mean square of the surface EMG at each knee joint angle was calculated and normalized by that at a knee joint angle of 90° for individual muscles. The normalized RMS of the VI muscle was significantly lower than those of the VL and RF muscles at the knee joint angles of 115° and 165° and those of the VL, VM, and RF muscles at the knee joint angle of 140° (P<0.05). The present results suggest that the neuromuscular activation of the VI muscle is regulated in a manner different from the alteration of the knee joint angle compared with other muscle components of the QF muscle group. © 2011 John Wiley & Sons A/S.

The U-shaped association between self-reported sleep duration and visual impairment in Korean adults: a population-based study.

PubMed

An, Youngju; Joo, Choun-Ki

2016-10-01

This study aimed to investigate the association between self-reported sleep duration and visual impairment (VI) in Korean adults. This population-based, cross-sectional study examined ophthalmologic data of 16,374 Koreans aged 19 years and older from the 2010-2012 Korea National Health and Nutrition Examination Survey (KNHNES V). VI data (best-corrected distance visual acuity worse than 0.5 logMAR in the better-seeing eye) were obtained from direct ophthalmologic examinations, and data on self-reported sleep duration (≤5, 6, 7, 8, or ≥9 h/night) were obtained using questionnaires. Multiple logistic regression analysis was conducted to examine the association between self-reported sleep duration and VI, and we also adjusted for possible covariates. The weighted VI prevalences (95% CIs) were 1.23% (0.70-1.76), 0.40% (0.10-0.70), 0.18% (0.04-0.31), 0.42% (0.26-0.58), and 0.66% (0.25-1.07) for participants who slept ≤5, 6, 7, 8, and ≥9 h/night, respectively. Even after adjusting for demographic factors (age and sex), lifestyle factors (household income, occupation, smoking status, regular exercise, and suicidal thoughts), and medical factors (diabetes, hypertension, stroke, and history of ocular surgery), greater risk of VI was found in the ≤5 h/night (OR = 3.23, 95% CI: 1.43-7.31) and ≥9 h/night (OR = 2.56, 95% CI: 1.03-6.41) groups, compared to the 7 h/night group. In Korean adults, self-reported sleep duration and VI exhibited a U-shaped association. Both very short (≤5 h/night) and very long (≥9 h/night) sleep durations were significantly associated with increased VI. Copyright © 2016 Elsevier B.V. All rights reserved.

Using Specific Binding DNA Capture Elements to Direct Pulsed Power Killing of Biological Agents

DTIC Science & Technology

2003-06-01

Department of the Air Force position, policy, or decision unless so designated by other documentation. VI. REFERENCES [1] V. Majidi and M. R. Joseph...Spectroscopic applications of laser-induced plasmas,” Crit. Rev. Analyt. Chem. 23, 143-162, 1992. [2] V. Majidi , “Laser-induced plasmas: A versatile tool

Physical activity does not influence the effect of antioxidant supplementation at nutritional doses on the incidence of impaired fasting glucose: a 7.5 year post-hoc analysis from the SU.VI.MAX study.

PubMed

Fezeu, L; Henegar, A; Kesse-Guyot, E; Julia, C; Galan, P; Hercberg, S; Ristow, M; Czernichow, S

2010-10-01

Supplementation with high doses of antioxidant vitamins prevents the insulin-sensitizing effects of physical exercise. However, little is known whether antioxidant supplementation affects the incidence of impaired fasting glucose (IFG). Data from 8938 subjects included in a randomized controlled trial on supplementation with antioxidants vitamins and trace elements at nutritional doses (SU.VI.MAX) were used to examine the effects of antioxidants on incident IFG after 7.5 years of follow-up, with and without stratification for daily physical exercise. The odds-ratio (95% CI) for developing an IFG among study participants receiving antioxidant supplementation was 1.34 (0.90-1.97) (p=0.33), in comparison to placebo. This risk did not vary significantly according to physical activity level (p for homogeneity=0.10). Supplementation with trace elements and antioxidants at nutritional doses apparently does not affect the incidence of IFG irrespective of self-reported physical exercise habits. © Georg Thieme Verlag KG Stuttgart · New York.

Effect of temporary cements on the shear bond strength of luting cements

PubMed Central

FIORI-JÚNIOR, Marco; MATSUMOTO, Wilson; SILVA, Raquel Assed Bezerra; PORTO-NETO, Sizenando Toledo; SILVA, Jaciara Miranda Gomes

2010-01-01

Objective The purpose of this study was to evaluate, by shear bond strength (SBS) testing, the influence of different types of temporary cements on the final cementation using conventional and self-etching resin-based luting cements. Material and Methods Forty human teeth divided in two halves were assigned to 8 groups (n=10): I and V (no temporary cementation); II and VI: Ca(OH)2-based cement; III and VII: zinc oxide (ZO)based cement; IV and VIII: ZO-eugenol (ZOE)-based cement. Final cementation was done with RelyX ARC cement (groups I to IV) and RelyX Unicem cement (groups V to VIII). Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. Results Means were (MPa): I - 3.80 (±1.481); II - 5.24 (±2.297); III - 6.98 (±1.885); IV - 6.54 (±1.459); V - 5.22 (±2.465); VI - 4.48 (±1.705); VII - 6.29 (±2.280); VIII - 2.47 (±2.076). Comparison of the groups that had the same temporary cementation (Groups II and VI; III and VII; IV and VIII) showed statistically significant difference (p<0.001) only between Groups IV and VIII, in which ZOE-based cements were used. The use of either Ca(OH)2 based (Groups II and VI) or ZO-based (Groups III and VII) cements showed no statistically significant difference (p>0.05) for the different luting cements (RelyXTM ARC and RelyXTM Unicem). The groups that had no temporary cementation (Groups I and V) did not differ significantly from each other either (p>0.05). Conclusion When temporary cementation was done with ZO- or ZOE-based cements and final cementation was done with RelyX ARC, there was an increase in the SBS compared to the control. In the groups cemented with RelyX Unicem, however, the use of a ZOE-based temporary cement affected negatively the SBS of the luting agent used for final cementation. PMID:20379679

Determination of the Inactivating Alterations in Two Mutant Alleles of the Neurospora Crassa Cross-Pathway Control Gene Cpc-1

PubMed Central

Paluh, J. L.; Plamann, M.; Kruger, D.; Barthelmess, I. B.; Yanofsky, C.; Perkins, D. D.

1990-01-01

cpc-1 is the locus specifying what is believed to be the major trans-activating transcription factor that regulates expression of amino acid biosynthetic genes subject to cross-pathway control in Neurospora crassa. Mutants altered at this locus are incapable of the global increase in gene expression normally seen in response to amino acid starvation. Using polymerase chain reaction methodology we have cloned and sequenced the inactive mutant allele, cpc-1 (CD15). The cpc-1 (CD15) mutation was found to be a single base pair deletion in codon 93 of the cpc-1 structural gene. A second, presumed lethal, allele, cpc-1 (j-5), also was investigated. Northern analyses with strains carrying the cpc-1 (j-5) allele revealed that no cpc-1 mRNA is produced. Southern and genetic analyses established that the cpc-1 (j-5) mutation involved a chromosomal rearrangement in which a break occurred within the cpc-1 locus, normally resident on linkage group VI; a small fragment from the left arm of linkage group VI, containing the cpc-1 promoter region and ylo-1, was translocated to the right arm of linkage group I. Other studies indicate that the cpc-1 locus itself is not essential for viability. Lethality previously attributed to the cpc-1 (j-5) mutation is due instead to the production of progeny that are deficient for essential genes in an adjoining segment of linkage group VI. Molecular characterization of cpc-1 (j-5) X ylo-1 pan-2 duplication progeny indicated that cpc-1 is normally transcribed towards the linkage group VI centromere. PMID:2138111

Ferrrate(VI) and freeze-thaw treatment for oxidation of hormones and inactivation of fecal coliforms in sludge.

PubMed

Diak, James; Örmeci, Banu

2017-04-01

This study examined the individual and combined effects of potassium ferrate(VI) additions and freeze-thaw conditioning for the treatment and dewatering of wastewater sludge in cold climates, with particular focus on the inactivation of fecal coliforms and oxidation of estrogens, androgens, and progestogens. The first phase of the study evaluated the effects of potassium ferrate(VI) pre-treatment followed by freeze-thaw at -20 °C using a low (0.5 g/L) and high (5.0 g/L) dose of potassium ferrate(VI). The results showed that pre-treatment of anaerobically digested sludge with 5 g/L of potassium ferrate(VI) reduced the concentration of fecal coliforms in the sludge cake to below 100 MPN/g DS. The second phase evaluated the ability of ferrate(VI) to oxidise selected hormones in sludge. Anaerobically digested sludge samples were spiked with 10 different hormones: estrone (E1), 17α-estradiol, 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2), equilin, mestranol, testosterone, norethindrone and norgestrel in two groups of low (3-75 ng/mL) and high (12-300 ng/L) concentration ranges of hormones. The samples were treated with either 0.5 or 1.0 g/L of potassium ferrate(VI), and hormone concentrations were measured again after treatment. Potassium ferrate(VI) additions as low as 1.0 g/L reduced the concentration of estrogens in sludge. Potassium ferrate(VI) additions of 0.5 and 1.0 g/L were less effective at reducing the concentrations of androgens and progestogens. Increasing ferrate(VI) dose would likely result in more substantial decreases in the concentrations of fecal coliforms and hormones. The results of this study indicate that the combined use of freeze-thaw and ferrate(VI) has the potential to provide a complete sludge treatment solution in cold regions.

Prevalence and Causes of Visual Impairment and Blindness in Chinese American Adults: The Chinese American Eye Study.

PubMed

Varma, Rohit; Kim, Jeniffer S; Burkemper, Bruce S; Wen, Ge; Torres, Mina; Hsu, Chunyi; Choudhury, Farzana; Azen, Stanley P; McKean-Cowdin, Roberta

2016-07-01

Visual impairment (VI) and blindness continue to be major public health problems worldwide. Despite previously published studies on VI in Chinese and other racial/ethnic populations, there are no data specific to Chinese American adults. To determine the age- and sex-specific prevalence and causes of VI and blindness in adult Chinese Americans and to compare the prevalence to other racial/ethnic groups. In this population-based, cross-sectional study of 10 US Census tracts in the city of Monterey Park, California, 4582 Chinese American adults 50 years and older underwent complete ophthalmologic examinations, including measurement of presenting and best-corrected visual acuity (BCVA) for distance using the Early Treatment Diabetic Retinopathy Study protocol from February 1, 2010, through October 31, 2013. Age-specific prevalence and causes of VI and blindness for presenting and BCVA. Of the 5782 eligible adults, 4582 (79.2%) completed an in-clinic eye examination. Of the 4582 participants, most were born in China (3149 [68.7%]), female (2901 [63.3%]), and married (3458 [75.5%]). The mean (SD) age was 61 (9) years. The prevalence of presenting VI was 3.0% (95% CI, 2.5%-3.5%), with 60.0% of this prevalence being attributed to uncorrected refractive error. The overall age-adjusted prevalence for VI (BCVA of ≤20/40 in the better eye) was 1.2% (95% CI, 0.9%-1.5%). The overall age-adjusted prevalence of blindness (BCVA of ≤20/200 in the better-seeing eye) was 0.07% (95% CI, 0%-0.2%). The prevalence of VI and blindness was higher in older Chinese Americans compared with younger. The primary causes of VI were cataracts and myopic retinopathy; the primary cause of blindness was myopic retinopathy. The prevalence of VI in Chinese Americans is similar to that of non-Hispanic white and Latino individuals in the United States and similar to or lower than the prevalence previously reported for Chinese adults from non-US studies. The prevalence of blindness is lower than that noted in other US or non-US studies. Myopic retinopathy is a frequent cause of VI and blindness in Chinese Americans that has not been commonly observed in other racial/ethnic groups. Because myopia frequently develops at a young age, Chinese Americans should be educated regarding the importance of regular screening of preschool and school-aged children to reduce the development and progression of myopia.

Adsorption of hexavalent chromium on cationic cross-linked starches of different botanic origins.

PubMed

Klimaviciute, Rima; Bendoraitiene, Joana; Rutkaite, Ramune; Zemaitaitis, Algirdas

2010-09-15

The influence of origin of native starch used to obtain cationic cross-linked starch (CCS) on the adsorption of Cr(VI) onto CCS has been investigated. CCS granule size is influenced by the botanic source of native starch. The equilibrium adsorption of Cr(VI) onto CCS was described by the Langmuir, Freundlich, Dubinin-Radushkevich and Temkin models. The more equal the adsorption energy of the quaternary ammonium groups in CCS granule as indicated by low value of change of Temkin adsorption energy DeltaE(T) the greater amount of Cr(VI) was adsorbed onto CCS. The value of DeltaE(T) decreased and sorption capacity of CCS increased with the decrease of CCS granule size and with the increase of number of amorphous regions in CCS granules. The affinity of dichromate anions increases and adsorption proceeds more spontaneously when Cr(VI) is adsorbed onto more amorphous CCS. Adsorption process of Cr(VI) onto such CCS is more exothermic and order of system undergoes major changes during adsorption. After the adsorption on CCS Cr(VI) could be regenerated by incineration at temperature of 800 degrees C. Copyright 2010 Elsevier B.V. All rights reserved.

Site-specific incorporation of uranyl carbonate species at the calcite surface

NASA Astrophysics Data System (ADS)

Reeder, Richard J.; Elzinga, Evert J.; Tait, C. Drew; Rector, K. D.; Donohoe, Robert J.; Morris, David E.

2004-12-01

Spatially resolved luminescence spectra from U(VI) co-precipitated at the (101¯4) growth surface of synthetic calcite single crystals confirm heterogeneous incorporation corresponding to the distribution of structurally non-equivalent steps composing the vicinal surfaces of spiral growth hillocks. Spectral structure from U(VI) luminescence at the "-" vicinal regions and featureless, weak luminescence at the "+" vicinal regions are consistent with previously reported observations of enrichment at the former sites during calcite growth. Luminescence spectra differ between the non-equivalent regions of the crystal, with the spectral features from the "-" vicinal region corresponding to those observed in bulk calcite samples. Subtle spectral shifts are observed from U(VI) co-precipitated with microcrystalline calcite synthesized by a different method, and all of the U(VI)-calcite sample spectra differ significantly from that of U(VI) co-precipitated with aragonite. The step-selective incorporation of U(VI) can be explained by a proposed model in which the allowed orientation for adsorption of the dominant calcium uranyl triscarbonate species is controlled by the atomic arrangement at step edges. Differences in the tilt angles of carbonate groups between non-equivalent growth steps favor adsorption of the calcium uranyl triscarbonate species at "-" steps, as observed in experiments.

Chromium isotope variation along a contaminated groundwater plume: a coupled Cr(VI)- reduction, advective mixing perspective

NASA Astrophysics Data System (ADS)

Bullen, T.; Izbicki, J.

2007-12-01

Chromium (Cr) is a common contaminant in groundwater, used in electroplating, leather tanning, wood preservation, and as an anti-corrosion agent. Cr occurs in two oxidation states in groundwater: Cr(VI) is highly soluble and mobile, and is a carcinogen; Cr(III) is generally insoluble, immobile and less toxic than Cr(VI). Reduction of Cr(VI) to Cr(III) is thus a central issue in approaches to Cr(VI) contaminant remediation in aquifers. Aqueous Cr(VI) occurs mainly as the chromate (CrO22-) and bichromate (HCrO2-) oxyanions, while Cr(III) is mainly "hexaquo" Cr(H2O)63+. Cr has four naturally-occurring stable isotopes: 50Cr, 52Cr, 53Cr and 54Cr. When Cr(VI) is reduced to Cr(III), the strong Cr-O bond must be broken, resulting in isotopic selection. Ellis et al. (2002) demonstrated that for reduction of Cr(VI) on magnetite and in natural sediment slurries, the change of isotopic composition of the remnant Cr(VI) pool was described by a Rayleigh fractionation model having fractionation factor ɛCr(VI)-Cr(III) = 3.4‰. We attempted to use Cr isotopes as a monitor of Cr(VI) reduction at a field site in Hinkley, California (USA) where groundwater contaminated with Cr(VI) has been under assessment for remediation. Groundwater containing up to 5 ppm Cr(VI) has migrated down-gradient from the contamination source through the fluvial to alluvial sediments to form a well-defined plume. Uncontaminated groundwater in the aquifer immediately adjacent to the plume has naturally-occurring Cr(VI) of 4 ppb or less (CH2M-Hill). In early 2006, colleagues from CH2M-Hill collected 17 samples of groundwater from within and adjacent to the plume. On a plot of δ53Cr vs. log Cr(VI), the data array is strikingly linear and differs markedly from the trend predicted for reduction of Cr(VI) in the contaminated water. There appear to be two groups of data: four samples with δ53Cr >+2‰ and Cr(VI) <4 ppb, and 13 samples with δ53Cr <+2‰ and Cr(VI) >15 ppb. Simple mixing lines between the groundwater samples having <4 ppb Cr(VI), taken to be representative of regional groundwater, and the contaminated water do not pass through the remainder of the data, discounting a simple advective mixing scenario. We hypothesize a more likely scenario that involves both Cr(VI) reduction and advective mixing. As the plume initially expands downgradient, Cr(VI) in water at the leading edge encounters reductant in the aquifer resulting in limited Cr(VI) reduction. As a result of reduction, δ53Cr of Cr(VI) remaining in solution at the leading edge increases along the "reduction" trend from 0 to ~+2‰. Inevitable mixing of this water at the leading edge with regional groundwater results in a suitable mixing end-member to combine with Cr(VI) within the plume in order to explain the bulk of the remaining data. Neither Cr(VI) reduction nor advective mixing of plume and regional groundwaters can explain the data on their own, implying an interplay of at least these two processes during plume evolution. Ellis, A.S., Johnson, T.M. and Bullen, T.D. 2002, Science, 295, 2060-2062.

Flower-, wire-, and sheet-like MnO2-deposited diatomites: Highly efficient absorbents for the removal of Cr(VI).

PubMed

Du, Yucheng; Wang, Liping; Wang, Jinshu; Zheng, Guangwei; Wu, Junshu; Dai, Hongxing

2015-03-01

Flower-, wire-, and sheet-like MnO2-deposited diatomites have been prepared using a hydrothermal method with Mn(Ac)2, KMnO4 and/or MnSO4 as Mn source and diatomite as support. Physical properties of the materials were characterized by means of numerous analytical techniques, and their behaviors in the adsorption of chromium(VI) were evaluated. It is shown that the MnO2-deposited diatomite samples with different morphologies possessed high surface areas and abundant surface hydroxyl groups (especially the wire-like MnO2/diatomite sample). The wire-like MnO2/diatomite sample showed the best performance in the removal of Cr(VI), giving the maximum Cr(VI) adsorption capacity of 101 mg/g. Copyright © 2014. Published by Elsevier B.V.

Modern rather than Mesoarchaean oxidative weathering responsible for the heavy stable Cr isotopic signatures of the 2.95 Ga old Ijzermijn iron formation (South Africa)

NASA Astrophysics Data System (ADS)

Albut, Gülüm; Babechuk, Michael G.; Kleinhanns, Ilka C.; Benger, Manuela; Beukes, Nicolas J.; Steinhilber, Bernd; Smith, Albertus J. B.; Kruger, Stephanus J.; Schoenberg, Ronny

2018-05-01

Previously reported stable Cr isotopic fractionation in Archaean paleosols and iron formations (IFs) have been interpreted as a signature of oxidative weathering of Cr(III) to Cr(VI) in soils, and delivery of isotopically heavy Cr(VI) into the oceans. One of the oldest reported fingerprints of this process is isotopically heavy Cr preserved in the 2.95 Ga old Ijzermijn IF, Sinqeni Formation of the Mozaan Group (Pongola Supergroup), South Africa and could suggest that atmospheric free oxygen was present ca. 600 million years earlier than the Great Oxidation Event (GOE). However, fractionated stable Cr isotopic signatures have only been found to date in surface outcrop samples of the White Mfolozi Inlier exposed along the White Mfolozi River Gorge. In this study, the latter outcrop was resampled along with two drill cores of the Ijzermijn IF and a drill core of the Scotts Hill IF to represent multiple exposures of Mozaan Group IFs with different states of preservation. A detailed geochemical comparison on bulk samples of different units was undertaken using stable Cr isotopes coupled with trace and major elements. Outcrop iron-rich mudstones (Fe - lutites) show very low LOI [wt] %, and very low Fe(II)/Fetot ratios, and lower Ca and Mg relative to equivalent facies in drill cores, indicating the effects that oxidative recent surface weathering had on Fe/Mn-rich carbonate minerals of the IF. Overall rare earth element and yttrium (REE + Y) mixing models agree well with previous studies, confirming that they were minimally disturbed by weathering and are consistent with a high magnitude of continental solutes delivered in a near-shore depositional environment, with a minor contribution of hydrothermally derived fluids that upwelled into shallower depositional setting. Importantly, all drill core samples of this study revealed δ53/52Cr values within the igneous inventory, despite variable amounts of detrital Cr input that includes nearly detritus-free, chert/jasper-rich units. By contrast, a specific group of Fe-lutite samples near the base of White Mfolozi River outcrop bear fractionated Cr isotopic signatures with δ53/52Cr values up to 0.418‰. These outcrop samples also display unusually high U/Th ratios (max. 12.6) as well as enrichments of other elements (W, Tl, As, MREE) that far exceed that observed in correlative drill core units. These observations together with the lack of Cr isotopic fractionation in drill core samples lead us to propose that the heavy δ53/52Cr values of Fe-lutites from outcrop Ijzermijn IF samples reported here and in a previous study are the product of modern oxidative weathering rather than an indicator for Mesoarchaean oxidative weathering at ca. 2.95 Ga.

Effectiveness of a Wii balance board-based system (eBaViR) for balance rehabilitation: a pilot randomized clinical trial in patients with acquired brain injury

PubMed Central

2011-01-01

Background Acquired brain injury (ABI) is the main cause of death and disability among young adults. In most cases, survivors can experience balance instability, resulting in functional impairments that are associated with diminished health-related quality of life. Traditional rehabilitation therapy may be tedious. This can reduce motivation and adherence to the treatment and thus provide a limited benefit to patients with balance disorders. We present eBaViR (easy Balance Virtual Rehabilitation), a system based on the Nintendo® Wii Balance Board® (WBB), which has been designed by clinical therapists to improve standing balance in patients with ABI through motivational and adaptative exercises. We hypothesize that eBaViR, is feasible, safe and potentially effective in enhancing standing balance. Methods In this contribution, we present a randomized and controlled single blinded study to assess the influence of a WBB-based virtual rehabilitation system on balance rehabilitation with ABI hemiparetic patients. This study describes the eBaViR system and evaluates its effectiveness considering 20 one-hour-sessions of virtual reality rehabilitation (n = 9) versus standard rehabilitation (n = 8). Effectiveness was evaluated by means of traditional static and dynamic balance scales. Results The final sample consisted of 11 men and 6 women. Mean ± SD age was 47.3 ± 17.8 and mean ± SD chronicity was 570.9 ± 313.2 days. Patients using eBaViR had a significant improvement in static balance (p = 0.011 in Berg Balance Scale and p = 0.011 in Anterior Reaches Test) compared to patients who underwent traditional therapy. Regarding dynamic balance, the results showed significant improvement over time in all these measures, but no significant group effect or group-by-time interaction was detected for any of them, which suggests that both groups improved in the same way. There were no serious adverse events during treatment in either group. Conclusions The results suggest that eBaViR represents a safe and effective alternative to traditional treatment to improve static balance in the ABI population. These results have encouraged us to reinforce the virtual treatment with new exercises, so an evolution of the system is currently being developed. PMID:21600066

Effectiveness of a Wii balance board-based system (eBaViR) for balance rehabilitation: a pilot randomized clinical trial in patients with acquired brain injury.

PubMed

Gil-Gómez, José-Antonio; Lloréns, Roberto; Alcañiz, Mariano; Colomer, Carolina

2011-05-23

Acquired brain injury (ABI) is the main cause of death and disability among young adults. In most cases, survivors can experience balance instability, resulting in functional impairments that are associated with diminished health-related quality of life. Traditional rehabilitation therapy may be tedious. This can reduce motivation and adherence to the treatment and thus provide a limited benefit to patients with balance disorders. We present eBaViR (easy Balance Virtual Rehabilitation), a system based on the Nintendo® Wii Balance Board® (WBB), which has been designed by clinical therapists to improve standing balance in patients with ABI through motivational and adaptative exercises. We hypothesize that eBaViR, is feasible, safe and potentially effective in enhancing standing balance. In this contribution, we present a randomized and controlled single blinded study to assess the influence of a WBB-based virtual rehabilitation system on balance rehabilitation with ABI hemiparetic patients. This study describes the eBaViR system and evaluates its effectiveness considering 20 one-hour-sessions of virtual reality rehabilitation (n = 9) versus standard rehabilitation (n = 8). Effectiveness was evaluated by means of traditional static and dynamic balance scales. The final sample consisted of 11 men and 6 women. Mean ± SD age was 47.3 ± 17.8 and mean ± SD chronicity was 570.9 ± 313.2 days. Patients using eBaViR had a significant improvement in static balance (p = 0.011 in Berg Balance Scale and p = 0.011 in Anterior Reaches Test) compared to patients who underwent traditional therapy. Regarding dynamic balance, the results showed significant improvement over time in all these measures, but no significant group effect or group-by-time interaction was detected for any of them, which suggests that both groups improved in the same way. There were no serious adverse events during treatment in either group. The results suggest that eBaViR represents a safe and effective alternative to traditional treatment to improve static balance in the ABI population. These results have encouraged us to reinforce the virtual treatment with new exercises, so an evolution of the system is currently being developed.

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

Lee, H.B.; Wexler, J.P.; Scharf, S.C.

The effect of two antihypertensive agents (captopril and prazosin) and of digoxin on the efficiency of Tc-99m binding to RBCs was evaluated in the rat. RBCs were labeled with Tc-99m in vivo in six groups of rats: I-normotensive controls Wistar rat (WR), II-prazosin treated WR, III-spontaneously hypertensive rat (SHR), IV-prazosin-treated SHR, V-digoxin-treated WR, and VI-captopril-treated WR. The percentage of intravascular Tc-99m bound to RBC (%T) and the percentage of injected dose remaining intravascular 5 min after injection (%i.v.) were determined. Mean %T was 94.2, 83.8, 94.9, 86.1, 79.7, and 93.3 for groups I-VI respectively. Mean %I.V. was 96.4, 74.6, 94.9,more » 79.0, 74.4, and 87.4 for groups I-VI respectively. The findings demonstrate a significant reduction of RBC tagging with Tc-99m in rats treated with prazosin and digoxin but not with captopril. The data suggest a potential interference by patient medication with the performance of blood-pool studies.« less

Molecular and cellular mechanisms of hexavalent chromium-induced lung cancer: an updated perspective.

PubMed

Urbano, A M; Ferreira, L M R; Alpoim, M C

2012-03-01

For over a century, chromium (Cr) has found widespread industrial and commercial use, namely as a pigment, in the production of stainless steel and in chrome plating. The adverse health effects to the skin and respiratory tract of prolonged exposure to Cr have been known or suspected for a long time, but it was much more recently that the toxicity of this element was unequivocally attributed to its hexavalent state. Based on the combined results of extensive epidemiological studies, animal carcinogenicity studies and several types of other relevant data, authoritative regulatory agencies have found sufficient evidence to classify hexavalent chromium [Cr(VI)] compounds as encountered in the chromate production, chromate pigment production and chromium plating industries as carcinogenic to humans. Crucial for the development of novel strategies to prevent, detect and/or treat Cr(VI)-induced cancers is a detailed knowledge of the molecular and cellular mechanisms underlying these pathologies. Unfortunately, in spite of a considerable research effort, crucial facets of these mechanisms remain essentially unknown. This review is intended to provide a concise, integrated and critical perspective of the current state of knowledge concerning multiple aspects of Cr(VI) carcinogenesis. It will present recent theories of Cr(VI)-induced carcinogenesis and will include aspects not traditionally covered in other reviews, such as the possible involvement of the energy metabolism in this process. A brief discussion on the models that have been used in the studies of Cr(VI)-induced carcinogenicity will also be included, due to the impact of this parameter on the relevance of the results obtained.

Cr isotope fractionation factors for Cr(VI) reduction by a metabolically diverse group of bacteria

NASA Astrophysics Data System (ADS)

Basu, Anirban; Johnson, Thomas M.; Sanford, Robert A.

2014-10-01

Reduction of Cr(VI) is an important process that determines the geochemical behavior, mobility and bioavailability of Cr in both terrestrial and marine environments. Many metabolically diverse microorganisms possess Cr(VI) reduction capacity. Cr(VI) reduction fractionates Cr isotopes and thus 53Cr/52Cr ratios can be used to monitor Cr(VI) reduction and redox conditions. The magnitude of isotopic fractionation (ε) for a variety of microbial reduction mechanisms must be known for accurate interpretation of observed shifts in 53Cr/52Cr ratios. We determined isotopic fractionation factors for Cr(VI) reduction by metal reducers Geobacter sulfurreducens and Shewanella sp. strain NR, a denitrifying soil bacterium Pseudomonas stutzeri DCP-Ps1, and a sulfate reducer Desulfovibrio vulgaris. All bacteria investigated in this study produced significant Cr isotope fractionation. The fractionation (ε) for G. sulfurreducens, Shewanella sp. (NR), P. stutzeri DCP-Ps1, and D. vulgaris were -3.03‰ ± 0.12‰, -2.17‰ ± 0.22‰, -3.14‰ ± 0.13‰, and -3.01‰ ± 0.11‰, respectively. Despite differences in microbial strains in this study, the ε did not vary significantly except for Shewanella sp. (NR). Our results suggest that strong isotopic fractionation is induced during Cr(VI) reduction under electron donor poor (∼300 μM) conditions.

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

PubMed

Tadić, Valerija; Pring, Linda; Dale, Naomi

2013-01-01

Lack of sight compromises insight into other people's mental states. Little is known about the role of maternal language in assisting the development of mental state language in children with visual impairment (VI). To investigate mental state language strategies of mothers of school-aged children with VI and to compare these with mothers of comparable children with typically developing vision. To investigate whether the characteristics of mother-child discourse were associated with the child's socio-communicative competence. Mother-child discourse with twelve 6-12-year-old children with VI was coded during a shared book-reading narrative and compared with 14 typically sighted children matched in age and verbal ability. Mothers of children with VI elaborated more and made significantly more references to story characters' mental states and descriptive elaborations than mothers of sighted children. Mental state elaborations of mothers in the VI group related positively with the level produced by their children, with the association remaining after mothers' overall verbosity and children's developmental levels were controlled for. Frequency of maternal elaborations, including their mental state language, was related to socio-communicative competence of children with VI. The findings offer insights into the potential contribution of maternal verbal scaffolding to mentalistic language and social-communicative competences of children with VI. © 2013 Royal College of Speech and Language Therapists.

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

PubMed Central

Tadić, Valerija; Pring, Linda; Dale, Naomi

2013-01-01

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

Ni0 encapsulated in N-doped carbon nanotubes for catalytic reduction of highly toxic hexavalent chromium

NASA Astrophysics Data System (ADS)

Yao, Yunjin; Zhang, Jie; Chen, Hao; Yu, Maojing; Gao, Mengxue; Hu, Yi; Wang, Shaobin

2018-05-01

N-doped carbon nanotubes encapsulating Ni0 nanoparticles (Ni@N-C) were fabricated via thermal reduction of dicyandiamide and NiCl2·6H2O, and used to remove CrVI in polluted water. The resultant products present an excellent catalytic activity for CrVI reduction using formic acid under relatively mild conditions. The CrVI reduction efficiency of Ni@N-C was significantly affected by the preparation conditions including the mass of nickel salt and synthesis temperatures. The impacts of several reaction parameters, such as initial concentrations of CrVI and formic acid, solution pH and temperatures, as well as inorganic anions in solution on CrVI reduction efficiency were also evaluated in view of scalable industrial applications. Owing to the synergistic effects amongst tubes-coated Ni0, doped nitrogen, oxygen containing groups, and the configuration of carbon nanotubes, Ni@N-C catalysts exhibit excellent catalytic activity and recyclable capability for CrVI reduction. Carbon shell can efficiently protect inner Ni0 core and N species from corrosion and subsequent leaching, while Ni0 endows the Ni@N-C catalysts with ferromagnetism, so that the composites can be easily separated via a permanent magnet. This study opens up an avenue for design of N-doped carbon nanotubes encapsulating Ni0 nanoparticles with high CrVI removal efficiency and magnetic recyclability as low-cost catalysts for industrial applications.

Lorentzian three-metrics with degenerate Ricci tensors

NASA Astrophysics Data System (ADS)

McManus, Des J.

1995-03-01

A classification of Lorentzian three-metrics whose Ricci tensor satisfies Rij=λ1gij+λ2vivj with λ1 and λ2(≠0) constant where vivi=κ(=0 or ±1) is given. An explicit coordinate representation is given for all the metrics that admit a G4 group as their maximal isometry group. Those metrics that admit a G3 as their maximal isometry group belong to either Bianchi class VI0, or VII0, or VIII, or IX when κ ≠ 0, and to either Bianchi class III, or IV, or VI0, VIh, or VIII when κ=0. An explicit coordinate representation is given for all the inhomogeneous solutions in the case κ ≠ 0.

Hexavalent chromium reduction under fermentative conditions with lactate stimulated native microbial communities.

PubMed

Somenahally, Anil C; Mosher, Jennifer J; Yuan, Tong; Podar, Mircea; Phelps, Tommy J; Brown, Steven D; Yang, Zamin K; Hazen, Terry C; Arkin, Adam P; Palumbo, Anthony V; Van Nostrand, Joy D; Zhou, Jizhong; Elias, Dwayne A

2013-01-01

Microbial reduction of toxic hexavalent chromium (Cr(VI)) in-situ is a plausible bioremediation strategy in electron-acceptor limited environments. However, higher [Cr(VI)] may impose stress on syntrophic communities and impact community structure and function. The study objectives were to understand the impacts of Cr(VI) concentrations on community structure and on the Cr(VI)-reduction potential of groundwater communities at Hanford, WA. Steady state continuous flow bioreactors were used to grow native communities enriched with lactate (30 mM) and continuously amended with Cr(VI) at 0.0 (No-Cr), 0.1 (Low-Cr) and 3.0 (High-Cr) mg/L. Microbial growth, metabolites, Cr(VI), 16S rRNA gene sequences and GeoChip based functional gene composition were monitored for 15 weeks. Temporal trends and differences in growth, metabolite profiles, and community composition were observed, largely between Low-Cr and High-Cr bioreactors. In both High-Cr and Low-Cr bioreactors, Cr(VI) levels were below detection from week 1 until week 15. With lactate enrichment, native bacterial diversity substantially decreased as Pelosinus spp., and Sporotalea spp., became the dominant groups, but did not significantly differ between Cr concentrations. The Archaea diversity also substantially decreased after lactate enrichment from Methanosaeta (35%), Methanosarcina (17%) and others, to mostly Methanosarcina spp. (95%). Methane production was lower in High-Cr reactors suggesting some inhibition of methanogens. Several key functional genes were distinct in Low-Cr bioreactors compared to High-Cr. Among the Cr resistant microbes, Burkholderia vietnamiensis, Comamonas testosterone and Ralstonia pickettii proliferated in Cr amended bioreactors. In-situ fermentative conditions facilitated Cr(VI) reduction, and as a result 3.0 mg/L Cr(VI) did not impact the overall bacterial community structure.

Biosorption of Cr(VI) by Ceratocystis paradoxa MSR2 Using Isotherm Modelling, Kinetic Study and Optimization of Batch Parameters Using Response Surface Methodology

PubMed Central

Ramalingam, Chidambaram

2015-01-01

This study is focused on the possible use of Ceratocystis paradoxa MSR2 native biomass for Cr(VI) biosorption. The influence of experimental parameters such as initial pH, temperature, biomass dosage, initial Cr(VI) concentration and contact time were optimized using batch systems as well as response surface methodology (RSM). Maximum Cr(VI) removal of 68.72% was achieved, at an optimal condition of biomass dosage 2g L−1, initial Cr(VI) concentration of 62.5 mg L−1 and contact time of 60 min. The closeness of the experimental and the predicted values exhibit the success of RSM. The biosorption mechanism of MSR2 biosorbent was well described by Langmuir isotherm and a pseudo second order kinetic model, with a high regression coefficient. The thermodynamic study also revealed the spontaneity and exothermic nature of the process. The surface characterization using FT-IR analysis revealed the involvement of amine, carbonyl and carboxyl groups in the biosorption process. Additionally, desorption efficiency of 92% was found with 0.1 M HNO3. The Cr(VI) removal efficiency, increased with increase in metal ion concentration, biomass concentration, temperature but with a decrease in pH. The size of the MSR2 biosorbent material was found to be 80 μm using particle size analyzer. Atomic force microscopy (AFM) visualizes the distribution of Cr(VI) on the biosorbent binding sites with alterations in the MSR2 surface structure. The SEM-EDAX analysis was also used to evaluate the binding characteristics of MSR2 strain with Cr(VI) metals. The mechanism of Cr(VI) removal of MSR2 biomass has also been proposed. PMID:25822726

Exposure to Hexavalent Chromium Resulted in Significantly Higher Tissue Chromium Burden Compared With Trivalent Chromium Following Similar Oral Doses to Male F344/N Rats and Female B6C3F1 Mice

PubMed Central

Collins, Bradley J.; Stout, Matthew D.; Levine, Keith E.; Kissling, Grace E.; Fennell, Timothy R.; Walden, Ramsey; Abdo, Kamal; Pritchard, John B.; Fernando, Reshan A.; Burka, Leo T.; Hooth, Michelle J.

2010-01-01

In National Toxicology Program 2-year studies, hexavalent chromium [Cr(VI)] administered in drinking water was clearly carcinogenic in male and female rats and mice, resulting in small intestine epithelial neoplasms in mice at a dose equivalent to or within an order of magnitude of human doses that could result from consumption of chromium-contaminated drinking water, assuming that dose scales by body weight3/4 (body weight raised to the 3/4 power). In contrast, exposure to trivalent chromium [Cr(III)] at much higher concentrations may have been carcinogenic in male rats but was not carcinogenic in mice or female rats. As part of these studies, total chromium was measured in tissues and excreta of additional groups of male rats and female mice. These data were used to infer the uptake and distribution of Cr(VI) because Cr(VI) is reduced to Cr(III) in vivo, and no methods are available to speciate tissue chromium. Comparable external doses resulted in much higher tissue chromium concentrations following exposure to Cr(VI) compared with Cr(III), indicating that a portion of the Cr(VI) escaped gastric reduction and was distributed systemically. Linear or supralinear dose responses of total chromium in tissues were observed following exposure to Cr(VI), indicating that these exposures did not saturate gastric reduction capacity. When Cr(VI) exposure was normalized to ingested dose, chromium concentrations in the liver and glandular stomach were higher in mice, whereas kidney concentrations were higher in rats. In vitro studies demonstrated that Cr(VI), but not Cr(III), is a substrate of the sodium/sulfate cotransporter, providing a partial explanation for the greater absorption of Cr(VI). PMID:20843897

Exposure to hexavalent chromium resulted in significantly higher tissue chromium burden compared with trivalent chromium following similar oral doses to male F344/N rats and female B6C3F1 mice.

PubMed

Collins, Bradley J; Stout, Matthew D; Levine, Keith E; Kissling, Grace E; Melnick, Ronald L; Fennell, Timothy R; Walden, Ramsey; Abdo, Kamal; Pritchard, John B; Fernando, Reshan A; Burka, Leo T; Hooth, Michelle J

2010-12-01

In National Toxicology Program 2-year studies, hexavalent chromium [Cr(VI)] administered in drinking water was clearly carcinogenic in male and female rats and mice, resulting in small intestine epithelial neoplasms in mice at a dose equivalent to or within an order of magnitude of human doses that could result from consumption of chromium-contaminated drinking water, assuming that dose scales by body weight(3/4) (body weight raised to the 3/4 power). In contrast, exposure to trivalent chromium [Cr(III)] at much higher concentrations may have been carcinogenic in male rats but was not carcinogenic in mice or female rats. As part of these studies, total chromium was measured in tissues and excreta of additional groups of male rats and female mice. These data were used to infer the uptake and distribution of Cr(VI) because Cr(VI) is reduced to Cr(III) in vivo, and no methods are available to speciate tissue chromium. Comparable external doses resulted in much higher tissue chromium concentrations following exposure to Cr(VI) compared with Cr(III), indicating that a portion of the Cr(VI) escaped gastric reduction and was distributed systemically. Linear or supralinear dose responses of total chromium in tissues were observed following exposure to Cr(VI), indicating that these exposures did not saturate gastric reduction capacity. When Cr(VI) exposure was normalized to ingested dose, chromium concentrations in the liver and glandular stomach were higher in mice, whereas kidney concentrations were higher in rats. In vitro studies demonstrated that Cr(VI), but not Cr(III), is a substrate of the sodium/sulfate cotransporter, providing a partial explanation for the greater absorption of Cr(VI).

Refining and Mutual Separation of Rare Earths Using Biomass Wastes

NASA Astrophysics Data System (ADS)

Inoue, Katsutoshi; Alam, Shafiq

2013-10-01

Two different types of adsorption gels were prepared from biomass wastes. The first gel was produced from astringent persimmon peel rich in persimmon tannin, a polyphenol compound, which was prepared by means of simple dehydration condensation reaction using concentrated sulfuric acid for crosslinking. This adsorption gel was intended to be employed for the removal of radioactive elements, uranium (U(VI)) and thorium (Th(IV)), from rare earths. The second gel was prepared from chitosan, a basic polysaccharide, produced from shells of crustaceans such as crabs, shrimps, prawns, and other biomass wastes generated in marine product industry, by immobilizing functional groups of complexanes such as ethylendiaminetetraacetic acid and diethylentriaminepentaacetic acid (DTPA). This gel was developed for the mutual separation of rare earths. Of the two adsorption gels evaluated, the DTPA immobilized chitosan exhibited the most effective mutual separation among light rare earths.

Alloy design for intrinsically ductile refractory high-entropy alloys

NASA Astrophysics Data System (ADS)

Sheikh, Saad; Shafeie, Samrand; Hu, Qiang; Ahlström, Johan; Persson, Christer; Veselý, Jaroslav; Zýka, Jiří; Klement, Uta; Guo, Sheng

2016-10-01

Refractory high-entropy alloys (RHEAs), comprising group IV (Ti, Zr, Hf), V (V, Nb, Ta), and VI (Cr, Mo, W) refractory elements, can be potentially new generation high-temperature materials. However, most existing RHEAs lack room-temperature ductility, similar to conventional refractory metals and alloys. Here, we propose an alloy design strategy to intrinsically ductilize RHEAs based on the electron theory and more specifically to decrease the number of valence electrons through controlled alloying. A new ductile RHEA, Hf0.5Nb0.5Ta0.5Ti1.5Zr, was developed as a proof of concept, with a fracture stress of close to 1 GPa and an elongation of near 20%. The findings here will shed light on the development of ductile RHEAs for ultrahigh-temperature applications in aerospace and power-generation industries.

Split Personality of a Potyvirus: To Specialize or Not to Specialize?

PubMed Central

Kehoe, Monica A.; Coutts, Brenda A.; Buirchell, Bevan J.; Jones, Roger A. C.

2014-01-01

Bean yellow mosaic virus (BYMV), genus Potyvirus, has an extensive natural host range encompassing both dicots and monocots. Its phylogenetic groups were considered to consist of an ancestral generalist group and six specialist groups derived from this generalist group during plant domestication. Recombination was suggested to be playing a role in BYMV's evolution towards host specialization. However, in subsequent phylogenetic analysis of whole genomes, group names based on the original hosts of isolates within each of them were no longer supported. Also, nine groups were found and designated I-IX. Recombination analysis was conducted on the complete coding regions of 33 BYMV genomes and two genomes of the related Clover yellow vein virus (CYVV). This analysis found evidence for 12 firm recombination events within BYMV phylogenetic groups I–VI, but none within groups VII–IX or CYVV. The greatest numbers of recombination events within a sequence (two or three each) occurred in four groups, three which formerly constituted the single ancestral generalist group (I, II and IV), and group VI. The individual sequences in groups III and V had one event each. These findings with whole genomes are consistent with recombination being associated with expanding host ranges, and call into question the proposed role of recombination in the evolution of BYMV, where it was previously suggested to play a role in host specialization. Instead, they (i) indicate that recombination explains the very broad natural host ranges of the three BYMV groups which infect both monocots and dicots (I, II, IV), and (ii) suggest that the three groups with narrow natural host ranges (III, V, VI) which also showed recombination now have the potential to reduce host specificity and broaden their natural host ranges. PMID:25148372

Identification of Near-infrared [Se III] and [Kr VI] Emission Lines in Planetary Nebulae

NASA Astrophysics Data System (ADS)

Sterling, N. C.; Madonna, S.; Butler, K.; García-Rojas, J.; Mashburn, A. L.; Morisset, C.; Luridiana, V.; Roederer, I. U.

2017-05-01

We identify [Se III] 1.0994 μm in the planetary nebula (PN) NGC 5315 and [Kr VI] 1.2330 μm 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 μm is particularly valuable when paired with observations of [Se IV] 2.2864 μm, 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 Se2+ and Kr5+, which we use to compute ionic abundances. In NGC 5315, we find that the Se abundance computed from Se3+/H+ is lower than that determined with ICFs that incorporate Se2+/H+. We compute new Kr ICFs that take Kr5+/H+ 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. This paper includes data obtained with the 6.5-m Magellan Telescopes at Las Campanas Observatory, Chile.

Uranium (VI) solubility in carbonate-free ERDA-6 brine

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

Lucchini, Jean-francois; Khaing, Hnin; Reed, Donald T

2010-01-01

When present, uranium is usually an element of importance in a nuclear waste repository. In the Waste Isolation Pilot Plant (WIPP), uranium is the most prevalent actinide component by mass, with about 647 metric tons to be placed in the repository. Therefore, the chemistry of uranium, and especially its solubility in the WIPP conditions, needs to be well determined. Long-term experiments were performed to measure the solubility of uranium (VI) in carbonate-free ERDA-6 brine, a simulated WIPP brine, at pC{sub H+} values between 8 and 12.5. These data, obtained from the over-saturation approach, were the first repository-relevant data for themore » VI actinide oxidation state. The solubility trends observed pointed towards low uranium solubility in WIPP brines and a lack of amphotericity. At the expected pC{sub H+} in the WIPP ({approx} 9.5), measured uranium solubility approached 10{sup -7} M. The objective of these experiments was to establish a baseline solubility to further investigate the effects of carbonate complexation on uranium solubility in WIPP brines.« less

32 CFR 536.77 - Applicable law for claims under the Military Claims Act.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) The United States will only be liable for the portion of loss or damage attributable to the fault of... preparation and presentation of the claim. (vi) Punitive or exemplary damages are not payable. (vii) Claims... will be considered as an element of damages under paragraph (b)(3)(ii) of this section. Claims for...

32 CFR 536.77 - Applicable law for claims under the Military Claims Act.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) The United States will only be liable for the portion of loss or damage attributable to the fault of... preparation and presentation of the claim. (vi) Punitive or exemplary damages are not payable. (vii) Claims... will be considered as an element of damages under paragraph (b)(3)(ii) of this section. Claims for...

32 CFR 536.77 - Applicable law for claims under the Military Claims Act.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) The United States will only be liable for the portion of loss or damage attributable to the fault of... preparation and presentation of the claim. (vi) Punitive or exemplary damages are not payable. (vii) Claims... will be considered as an element of damages under paragraph (b)(3)(ii) of this section. Claims for...

14 CFR Appendix A to Part 43 - Major Alterations, Major Repairs, and Preventive Maintenance

Code of Federal Regulations, 2013 CFR

2013-01-01

... hub design. (iii) Changes in the governor or control design. (iv) Installation of a propeller governor.... (iv) Engine mounts. (v) Control system. (vi) Landing gear. (vii) Hull or floats. (viii) Elements of an... of gravity limits of the aircraft. (xii) Changes to the basic design of the fuel, oil, cooling...

25 CFR 900.70 - What elements are included in the compensation for a lease entered into between the Secretary and...

Code of Federal Regulations, 2012 CFR

2012-04-01

... interest paid or accrued; (e) Operation and maintenance expenses, to the extent not otherwise included in...) Monitoring and preventive maintenance of building structures and systems, including but not limited to: (i) Heating/ventilation/air conditioning; (ii) Plumbing; (iii) Electrical; (iv) Elevators; (v) Boilers; (vi...

25 CFR 900.70 - What elements are included in the compensation for a lease entered into between the Secretary and...

Code of Federal Regulations, 2014 CFR

2014-04-01

... interest paid or accrued; (e) Operation and maintenance expenses, to the extent not otherwise included in...) Monitoring and preventive maintenance of building structures and systems, including but not limited to: (i) Heating/ventilation/air conditioning; (ii) Plumbing; (iii) Electrical; (iv) Elevators; (v) Boilers; (vi...

25 CFR 900.70 - What elements are included in the compensation for a lease entered into between the Secretary and...

Code of Federal Regulations, 2013 CFR

2013-04-01

... interest paid or accrued; (e) Operation and maintenance expenses, to the extent not otherwise included in...) Monitoring and preventive maintenance of building structures and systems, including but not limited to: (i) Heating/ventilation/air conditioning; (ii) Plumbing; (iii) Electrical; (iv) Elevators; (v) Boilers; (vi...

25 CFR 900.70 - What elements are included in the compensation for a lease entered into between the Secretary and...

Code of Federal Regulations, 2011 CFR

2011-04-01

... interest paid or accrued; (e) Operation and maintenance expenses, to the extent not otherwise included in...) Monitoring and preventive maintenance of building structures and systems, including but not limited to: (i) Heating/ventilation/air conditioning; (ii) Plumbing; (iii) Electrical; (iv) Elevators; (v) Boilers; (vi...

Differential effect of biochar upon reduction-induced mobility and bioavailability of arsenate and chromate.

PubMed

Choppala, Girish; Bolan, Nanthi; Kunhikrishnan, Anitha; Bush, Richard

2016-02-01

Heavy metals such as chromium (Cr) and arsenic (As) occur in ionic form in soil, with chromate [Cr(VI)] and arsenate As(V) being the most pre-dominant forms. The application of biochar to Cr(VI) and As(V) spiked and field contaminated soils was evaluated on the reduction processes [(Cr(VI) to Cr(III)] and [As(V) to As(III))], and subsequent mobility and bioavailability of both As(V) and Cr(VI). The assays used in this study included leaching, soil microbial activity and XPS techniques. The reduction rate of As(V) was lower than that of Cr(VI) with and without biochar addition, however, supplementation with biochar enhanced the reduction process of As(V). Leaching experiments indicated Cr(VI) was more mobile than As(V). Addition of biochar reversed the effect by reducing the mobility of Cr and increasing that of As. The presence of Cr and As in both spiked and contaminated soils reduced microbial activity, but with the addition of biochar to these soils, the microbial activity increased in the Cr(VI) contaminated soils, while it was further decreased with As(V) contaminated soils. The addition of biochar was effective in mitigating Cr toxicity by reducing Cr(VI) to Cr(III). In contrast, the conversion process of As(V) to As(III) hastened by biochar was not favourable, as As(III) is more toxic in soils. Overall, the presence of functional groups on biochar promotes reduction by providing the electrons required for reduction processes to occur as determined by XPS data. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nb2O5 nanowires in-situ grown on carbon fiber: A high-efficiency material for the photocatalytic reduction of Cr(VI).

PubMed

Du, Yucheng; Zhang, Shihao; Wang, Jinshu; Wu, Junshu; Dai, Hongxing

2018-04-01

Niobium oxide nanowire-deposited carbon fiber (CF) samples were prepared using a hydrothermal method with amorphous Nb 2 O 5 ·nH 2 O as precursor. The physical properties of the samples were characterized by means of numerous techniques, including X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), UV-visible spectroscopy (UV-vis), N 2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy. The efficiency for the removal of Cr(VI) was determined. Parameters such as pH value and initial Cr(VI) concentration could influence the Cr(VI) removal efficiency or adsorption capacity of the Nb 2 O 5 /carbon fiber sample obtained after hydrothermal treatment at 160°C for 14hr. The maximal Cr(VI) adsorption capacity of the Nb 2 O 5 nanowire/CF sample was 115mg/g. This Nb 2 O 5 /CF sample also showed excellent photocatalytic activity and stability for the reduction of Cr(VI) under UV-light irradiation: the Cr(VI) removal efficiency reached 99.9% after UV-light irradiation for 1hr and there was no significant decrease in photocatalytic performance after the use of the sample for 10 repeated cycles. Such excellent Cr(VI) adsorption capacity and photocatalytic performance was related to its high surface area, abundant surface hydroxyl groups, and good UV-light absorption ability. Copyright © 2017. Published by Elsevier B.V.

Exposure to Particulate Hexavalent Chromium Exacerbates Allergic Asthma Pathology

PubMed Central

Schneider, Brent C.; Constant, Stephanie L.; Patierno, Steven R.; Jurjus, Rosalyn A.; Ceryak, Susan M.

2011-01-01

Airborne hexavalent chromate, Cr(VI), has been identified by the Environmental Protection Agency as a possible health threat in urban areas, due to the carcinogenic potential of some of its forms. Particulate chromates are produced in many different industrial settings, with high levels of aerosolized forms historically documented. Along with an increased risk of lung cancer, a high incidence of allergic asthma has been reported in workers exposed to certain inhaled particulate Cr(VI) compounds. However, a direct causal association between Cr(VI) and allergic asthma has not been established. We recently showed that inhaled particulate Cr(VI) induces an innate neutrophilic inflammatory response in BALB/c mice. In the current studies we investigated how the inflammation induced by inhaled particulate Cr(VI) might alter the pathology of an allergic asthmatic response. We used a well-established mouse model of allergic asthma. Groups of ovalbumin protein (OVA)-primed mice were challenged either with OVA alone, or with a combination of OVA and particulate zinc chromate, and various parameters associated with asthmatic responses were measured. Co-exposure to particulate Cr(VI) and OVA mediated a mixed form of asthma in which both eosinophils and neutrophils are present in airways, tissue pathology is markedly exacerbated, and airway hyperresponsiveness is significantly increased. Taken together these findings suggest that inhalation of particulate forms of Cr(VI) may augment the severity of ongoing allergic asthma, as well as alter its phenotype. Such findings may have implications for asthmatics in settings in which airborne particulate Cr(VI) compounds are present at high levels. PMID:22178736

Comparison of safety and immunogenicity of a Vi polysaccharide typhoid vaccine with a whole-cell killed vaccine in Malaysian Air Force recruits.

PubMed Central

Panchanathan, V.; Kumar, S.; Yeap, W.; Devi, S.; Ismail, R.; Sarijan, S.; Sam, S. M.; Jusoh, Z.; Nordin, S.; Leboulleux, D.; Pang, T.

2001-01-01

OBJECTIVE: To carry out a comparative study of the safety and immunogenicity of Vi polysaccharide vaccine against whole-cell killed (WCK) typhoid vaccine. METHODS: The study was carried out on young adult recruits (aged 18-25 years) of the Malaysian Air Force. A total of 125 subjects received the Vi polysaccharide vaccine and 114 received the WCK vaccine. FINDINGS: The Vi vaccine was significantly less reactogenic than the WCK vaccine with regard to systemic and local reactions. Following administration of the Vi vaccine, seroconversion rates (defined as the percentage of subjects with a 4-fold rise of baseline antibody level) of 75.5% and 67% were observed at 2 weeks and 6 weeks, respectively, after immunization, compared with 25% and 31.3% among recipients of the WCK vaccine. Of the 110 Vi vaccinees with serological data, 21 (19%) had high, seroprotective, pre-immunization levels of anti-Vi antibodies (> or = 1 microgram/ml). The majority of subjects in this group came from a region in Malaysia which is known to have high typhoid endemicity. Interestingly, these antibody levels were boosted considerably following administration of vaccine at a level that was 5-fold higher than in subjects with low pre-immunization levels. In contrast, the seroconversion rates in those receiving the Vi vaccine were higher in subjects with low pre-immunization levels of anti-Vi antibodies (76-84%), compared to those with protective levels of > or = 1 microgram/ml prior to immunization (48-57%). CONCLUSIONS: The study reaffirms the safety and efficacy of the Vi polysaccharide vaccine and identifies a hitherto unrecognized advantage in its use, i.e. it is a potent immunogen that boosted considerably the protective antibody levels among a significant number of immunologically sensitized individuals living in typhoid-endemic regions. PMID:11584728

Exposure to particulate hexavalent chromium exacerbates allergic asthma pathology

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

Schneider, Brent C.; Department of Pharmacology and Physiology, The George Washington University, Washington, DC 20037; Constant, Stephanie L.

Airborne hexavalent chromate, Cr(VI), has been identified by the Environmental Protection Agency as a possible health threat in urban areas, due to the carcinogenic potential of some of its forms. Particulate chromates are produced in many different industrial settings, with high levels of aerosolized forms historically documented. Along with an increased risk of lung cancer, a high incidence of allergic asthma has been reported in workers exposed to certain inhaled particulate Cr(VI) compounds. However, a direct causal association between Cr(VI) and allergic asthma has not been established. We recently showed that inhaled particulate Cr(VI) induces an innate neutrophilic inflammatory responsemore » in BALB/c mice. In the current studies we investigated how the inflammation induced by inhaled particulate Cr(VI) might alter the pathology of an allergic asthmatic response. We used a well-established mouse model of allergic asthma. Groups of ovalbumin protein (OVA)-primed mice were challenged either with OVA alone, or with a combination of OVA and particulate zinc chromate, and various parameters associated with asthmatic responses were measured. Co-exposure to particulate Cr(VI) and OVA mediated a mixed form of asthma in which both eosinophils and neutrophils are present in airways, tissue pathology is markedly exacerbated, and airway hyperresponsiveness is significantly increased. Taken together these findings suggest that inhalation of particulate forms of Cr(VI) may augment the severity of ongoing allergic asthma, as well as alter its phenotype. Such findings may have implications for asthmatics in settings in which airborne particulate Cr(VI) compounds are present at high levels. -- Highlights: ► Allergic asthma correlated with exposure to certain inhaled particulate chromates. ► Direct causal association between Cr(VI) and allergic asthma not established. ► Cr exacerbated pathology and airway hyperresponsiveness in an OVA-challenged mouse. ► Particulate Cr(VI) may augment severity and alter phenotype of ongoing allergic asthma.« less

Apical Transportation, Centering Ratio, and Volume Increase after Manual, Rotary, and Reciprocating Instrumentation in Curved Root Canals: Analysis by Micro-computed Tomographic and Digital Subtraction Radiography.

PubMed

Zanesco, Caroline; Só, Marcus Vinicius Reis; Schmidt, Sabrina; Fontanella, Vania Regina Camargo; Grazziotin-Soares, Renata; Barletta, Fernando Branco

2017-03-01

This study aimed to evaluate apical transportation (AT), centering ratio (CR), and volume increase (VI) produced after instrumentation of mesiobuccal canals of maxillary molars with hand files, rotary, and reciprocating instruments using micro-computed tomographic (micro-CT) imaging and to demonstrate the ability of digital subtraction radiography (DSR) to evaluate AT. Forty-five canals were randomly assigned to either group K, manual K-files; PTN, ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland); or Rec, Reciproc (n = 15 for each group) for preparation. Master apical files were #25, X2 (#25/06), and R25 (#25/08), respectively. Micro-CT imaging was used to measure AT (mm) and CR (mm) at 3 different locations (1, 4, and 7 mm from the apex). VI (mm 3 ) was measured for each root third and for the whole canal. DSR (mesiodistal and buccolingual projections) was used to measure AT at 1 mm from the apex. AT and CR values were statistically similar across the groups at 1, 4, and 7 mm. AT results obtained for the different locations were similar within each group; CR, in turn, showed statistically lower values at 1 mm. VI was statistically similar in all groups. Both DSR and micro-CT imaging showed that AT always occurred on the outside of canal curvature. The highest mean value obtained for AT was 0.215 mm. AT, CR, and VI were similar for the K, PTN, and Rec groups. AT results were clinically irrelevant. DSR was as effective as micro-CT imaging in AT analysis and could be considered as an alternative method for assessing this outcome. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

[Enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to Salmonella Typhi lipopolysaccharide O and capsular polysaccharide Vi antigens in persons from outbreak of typhoid fever].

PubMed

Rastawicki, Waldemar; Kałużewski, Stanisław

2015-01-01

The laboratory diagnosis of typhoid fever is dependent upon either isolation of S. Typhi from a clinical sample or the detection of raised titers of serum antibodies in the Widal test or the passive hemagglutination assay (PHA). In this study we evaluated the usefulness of ELISA for detection of antibodies to S. Typhi lipopolysaccharide O and capsular polysaccharide Vi antigens in the sera of persons from outbreak of typhoid fever. Fifteen serum samples from patients with laboratory confirmed typhoid fever and 140 sera from persons suspected for contact with typhoid fever patients from outbreak in 1974/75 in Poland were tested by ELISA. Additionally, as the control group, we tested 115 sera from blood donors for the presence of S. Typhi anti-LPS and anti-Vi antibodies. Anti-LPS and anti-Vi antibodies were detected in 80% and 53.3% of sera obtained from patients with laboratory confirmed typhoid fever, respectively. The high percentages of positive results in ELISA were also noted in the group of persons suspected for contact with typhoid fever patients (51.4% and 45%) but not in the group of blood donors (7.8% and 6.1%, respectively). The ELISA could be a useful tool for the serological diagnosis of typhoid fever in patients who have clinical symptoms but are culture negative, especially during massive outbreaks of typhoid fever.

Adsorption of hexavalent chromium on modified corn stalk using different cross-linking agents

NASA Astrophysics Data System (ADS)

Chen, Suhong; Zhu, Yi; Han, Zhijun; Feng, Gao; Jia, Yuling; Fu, Kaifang; Yue, Qinyan

2017-12-01

In this study, four different types of adsorbents modified from corn stalk were synthesized after the reaction with epichlorohydrin, N,N-dimethylformamide, triethylamine and different cross-linking agents. The surface functional groups and thermal stability of modified corn stalk (MCSs) were characterized using FTIR and TG analysis, respectively. The feasibility of using MCSs to remove Cr(VI) were evaluated. Adsorption isotherms were determined and modeled with Langmuir, Freundlich and Temkin equations. The experimental results showed that MCS modified using diethylenetriamine (DETA) had the best modification effect, and the adsorption capacity of Cr(VI) reached as high as 227.27 mg/g at 323 K. Thermodynamic study showed that the Cr(VI) adsorption onto MCSs was endothermic processes. As a result, MCS by using DETA as cross-linking agent has good potential for the removal of Cr(VI) from aqueous solutions.

Behavior of Colorado Plateau uranium minerals during oxidation

USGS Publications Warehouse

Garrels, Robert Minard; Christ, C.L.

1956-01-01

Uranium occurs as U(VI) and U(IV) in minerals of the Colorado Plateau ores. The number of species containing U(VI) is large, but only two U(IV) minerals are known from the Plateau: uraninite, and oxide, and coffinite, a hydroxy-silicate. These oxidize to yield U(VI) before reacting significantly with other mineral constituents. Crystal-structure analysis has shown that U(VI) invariable occurs as uranyl ion, UO2+2. Uranyl ion may form complex carbonate or sulfate ions with resulting soluble compounds, but only in the absence of quinquevalent vanadium, arsenic, or phosphorous. In the presence of these elements in the +5 valence state, the uranyl ion is fixed in insoluble layer compounds formed by union of uranyl ion with orthovanadate, orthophosphate, or orthoarsenate. Under favorable conditions UO2+2 may react to form the relatively insoluble rutherfordine, UO2CO3, or hydrated uranyl hydroxides. These are rarely found on the Colorado Plateau as opposed to their excellent development in other uraniferous areas, a condition which is apparently related to the semiarid climate and low water table of the Plateau. Uranium may also be fixed as uranyl silicate, but little is known about minerals of this kind. In the present study emphasis has been placed on a detailing of the chemical and crystal structural changes which occur in the oxidation paragenetic sequence.

Synthesis, properties and applications of 2D layered MIIIXVI (M = Ga, In; X = S, Se, Te) materials.

PubMed

Xu, Kai; Yin, Lei; Huang, Yun; Shifa, Tofik Ahmed; Chu, Junwei; Wang, Feng; Cheng, Ruiqing; Wang, Zhenxing; He, Jun

2016-09-29

Group III-VI compounds M III X VI (M = Ga, In; X = S, Se, Te) are one class of important 2D layered materials and are currently attracting increasing interest due to their unique electronic and optoelectronic properties and their great potential applications in various other fields. Similar to 2D layered transition metal dichalcogenides (TMDs), M III X VI also have the significant merits of ultrathin thickness, ultrahigh surface-to-volume ratio, and high compatibility with flexible devices. More impressively, in contrast with TMDCs, M III X VI demonstrate many superior properties, such as direct band gap electronic structure, high carrier mobility, rare p-type electronic behaviors, high charge density, and so on. These unique characteristics cause high-performance device applications in electronics, optoelectronics, and optics. In this review, we aim to provide a summary of the state-of-the-art of research activities in 2D layered M III X VI materials. The scope of the review covers the synthesis and properties of 2D layered M III X VI materials and their van der Waals heterostructures. We especially focus on the applications in electronics and optoelectronics. Moreover, the review concludes with some perspectives on future developments in this field.

Stellar Laboratories: New GeV and Ge VI Oscillator Strengths and their Validation in the Hot White Dwarf RE0503-289

NASA Technical Reports Server (NTRS)

Rauch, T.; Werner, K.; Biemont, E.; Quinet, P.; Kruk, J. W.

2013-01-01

State-of-the-art spectral analysis of hot stars by means of non-LTE model-atmosphere techniques has arrived at a high level of sophistication. The analysis of high-resolution and high-S/N spectra, however, is strongly restricted by the lack of reliable atomic data for highly ionized species from intermediate-mass metals to trans-iron elements. Especially data for the latter has only been sparsely calculated. Many of their lines are identified in spectra of extremely hot, hydrogen-deficient post-AGB stars. A reliable determination of their abundances establishes crucial constraints for AGB nucleosynthesis simulations and, thus, for stellar evolutionary theory. Aims. In a previous analysis of the UV spectrum of RE 0503-289, spectral lines of highly ionized Ga, Ge, As, Se, Kr, Mo, Sn, Te, I, and Xe were identified. Individual abundance determinations are hampered by the lack of reliable oscillator strengths. Most of these identified lines stem from Ge V. In addition, we identified Ge VI lines for the first time. We calculated Ge V and Ge VI oscillator strengths in order to reproduce the observed spectrum. Methods. We newly calculated Ge V and Ge VI oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our non-LTE stellar-atmosphere models for the analysis of the Ge IV-VI spectrum exhibited in high-resolution and high-S/N FUV (FUSE) and UV (ORFEUS/BEFS, IUE) observations of RE 0503-289. Results. In the UV spectrum of RE 0503-289, we identify four Ge IV, 37 Ge V, and seven Ge VI lines. Most of these lines are identified for the first time in any star. We can reproduce almost all Ge IV, GeV, and Ge VI lines in the observed spectrum of RE 0503-289 (T(sub eff) = 70 kK, log g = 7.5) at log Ge = -3.8 +/- 0.3 (mass fraction, about 650 times solar). The Ge IV/V/VI ionization equilibrium, that is a very sensitive T(sub eff) indicator, is reproduced well. Conclusions. Reliable measurements and calculations of atomic data are a prerequisite for stellar-atmosphere modeling. Our oscillator-strength calculations have allowed, for the first time, Ge V and Ge VI lines to be successfully reproduced in a white dwarf s (RE 0503-289) spectrum and to determine its photospheric Ge abundance.

Sequential Leaching of Chromium Contaminated Sediments - A Study Characterizing Natural Attenuation

NASA Astrophysics Data System (ADS)

Musa, D.; Ding, M.; Beroff, S.; Rearick, M.; Perkins, G.; WoldeGabriel, G. W.; Ware, D.; Harris, R.; Kluk, E.; Katzman, D.; Reimus, P. W.; Heikoop, J. M.

2015-12-01

Natural attenuation is an important process in slowing down the transport of hexavalent chromium, Cr(VI), an anthropogenic environmental contaminant, either by adsorption of Cr(VI) to sediments, or by reduction to nontoxic trivalent chromium, Cr(III). The capacity and mechanism of attenuation is explored in this sequential leaching study of different particle size fractions of chromium contaminated sediments and similar uncontaminated sediments from the regional aquifer near Los Alamos, New Mexico. Using this leaching protocol each sediment sample is split in two: one half is leached three times using a 0.1 M sodium bicarbonate/carbonate solution, while the second half is leached three times using a 0.01 M nitric acid, followed by two consecutively increasing magnitudes of nitric acid concentrations. Based on the amphoteric nature of chromium, alkaline leaching is used to establish the amount of Cr(VI) sorbed on the sediment, whereas acid leaching is used to establish the amount of Cr(III). The weak acid is predicted to release the attenuated anthropogenic Cr(III), without affecting Cr-bearing minerals. The sequential, stronger, acid is anticipated to leach Cr(III)-incorporated in the minerals. The efficiency and validation of the sequential leaching method is assessed by comparing the leaching behavior of bentonite and biotite samples, with and without loaded Cr(VI). A 97% chromium mass balance of leached Cr(VI)-loaded bentonite and biotite proves the viability of this method for further use on leaching contaminated sediments. By comparing contaminated and uncontaminated sediment leachate results, of chromium and other major and trace elements, the signature of anthropogenic chromium is determined. Further mineralogical characterization of the sediments provides a quantitative measure of the natural attenuation capacity for chromium. Understanding these results is pertinent in delineating the optimal procedure for the remediation of Cr(VI) in the regional aquifer near Los Alamos.

Effect of available nitrogen on phytoavailability and bioaccumulation of hexavalent and trivalent chromium in hankow willows (Salix matsudana Koidz).

PubMed

Yu, Xiao-Zhang; Gu, Ji-Dong

2008-06-01

The effect of available nitrogen in nutrient solution on removal of two chemical forms of chromium (Cr) by plants was investigated. Pre-rooted hankow willows (Salix matsudana Koidz) were grown in a hydroponic solution system with or without nitrogen, and amended with hexavalent chromium [Cr (VI)] or trivalent chromium [Cr (III)] at 25.0+/-0.5 degrees C for 192 h. The results revealed that higher removal of Cr by plants was achieved from the hydroponic solutions without any nitrogen than those containing nitrogen. Although faster removal of Cr (VI) than Cr (III) was observed, translocation of Cr (III) within plant materials was more efficient than Cr (VI). Substantial difference existed in the distribution of Cr in different parts of plant tissues due to the nitrogen in nutrient solutions (p<0.05): lower stems were the major sink for both Cr species in willows grown in the N-free nutrient solutions and more Cr was accumulated in the roots of plants in N-containing ones. No significant difference was found in the removal rate of Cr (VI) between willows grown in the N-free and N-containing solutions (p>0.05). Removal rates of Cr (III) decreased linearly with the strength of nutrient solutions with or without N addition (p<0.01). Translocation efficiencies of both Cr species increased proportionally with the strength of N-containing nutrient solutions and decreased with the strength of N-free nutrient solutions. Results suggest that uptake and translocation mechanisms of Cr (VI) and Cr (III) are apparently different in hankow willows. The presence of easily available nitrogen and other nutrient elements in the nutrient solutions had a more pronounced influence on the uptake of Cr (III) than Cr (VI). Nitrogen availability and quantities in the ambient environment will affect the translocation of both Cr species and their distribution in willows in phytoremediation.

Comparison of placental three-dimensional power Doppler indices and volume in the first and second trimesters of pregnancy complicated by gestational diabetes mellitus.

PubMed

Wong, Chian-Huey; Chen, Chie-Pein; Sun, Fang-Ju; Chen, Chen-Yu

2018-05-01

To compare the changes of placental three-dimensional power Doppler indices and volume in the first and second trimesters of pregnancy with gestational diabetes mellitus (GDM). This was a prospective case-control study of singleton pregnancies with risk factors for GDM. Data on placental vascular indices including vascularization index (VI), flow index (FI), and vascularization flow index (VFI), as well as placental volume were obtained and analyzed during the first and second trimesters between pregnant women with and without GDM. Of the 155 pregnant women enrolled, 31 developed GDM and 124 did not. VI and VFI were significantly lower in the GDM group during the first and second trimesters (VI: p = 0.023, and VFI: p = 0.014 in the first trimester; VI: p = 0.049, and VFI: p = 0.031 in the second trimester). However, the placental volume was similar in both groups during the first trimester, while it was significantly increased in the GDM group during the second trimester (p = 0.022). There were no significant differences in FI and uterine artery pulsatility index between the two groups. After adjustments in multivariate logistic regression analysis, significant differences were observed in the first trimester VFI (adjusted odds ratio (OR) 0.76, 95% confidence interval (CI) 0.61-0.93), second trimester VFI (adjusted or 0.83, 95% CI 0.71-0.96), and second trimester placental volume (adjusted or 1.03, 95% CI 1.01-1.05). Placental vascular indices can provide an insight into placental vascularization in GDM during early pregnancy. VFI rather than placental volume may be a sensitive sonographic marker in the first trimester of GDM placentas.

Proteomic Discovery and Development of a Multiplexed Targeted MRM-LC-MS/MS Assay for Urine Biomarkers of Extracellular Matrix Disruption in Mucopolysaccharidoses I, II, and VI.

PubMed

Heywood, Wendy E; Camuzeaux, Stephane; Doykov, Ivan; Patel, Nina; Preece, Rhian-Lauren; Footitt, Emma; Cleary, Maureen; Clayton, Peter; Grunewald, Stephanie; Abulhoul, Lara; Chakrapani, Anupam; Sebire, Neil J; Hindmarsh, Peter; de Koning, Tom J; Heales, Simon; Burke, Derek; Gissen, Paul; Mills, Kevin

2015-12-15

The mucopolysaccharidoses (MPS) are lysosomal storage disorders that result from defects in the catabolism of glycosaminoglycans. Impaired muscle, bone, and connective tissue are typical clinical features of MPS due to disruption of the extracellular matrix. Markers of MPS disease pathology are needed to determine disease severity and monitor effects of existing and emerging new treatments on disease mechanisms. Urine samples from a small cohort of MPS-I, -II, and -VI patients (n = 12) were analyzed using label-free quantative proteomics. Fifty-three proteins including many associated with extracellular matrix organization were differently expressed. A targeted multiplexed peptide MRM LC-MS/MS assay was used on a larger validation cohort of patient samples (MPS-I n = 18, MPS-II n = 12, MPS-VI n = 6, control n = 20). MPS-I and -II groups were further subdivided according to disease severity. None of the markers assessed were altered significantly in the mild disease groups compared to controls. β-galactosidase, a lysosomal protein, was elevated 3.6-5.7-fold significantly (p < 0.05) in all disease groups apart from mild MPS-I and -II. Collagen type Iα, fatty-acid-binding-protein 5, nidogen-1, cartilage oligomeric matrix protein, and insulin-like growth factor binding protein 7 concentrations were elevated in severe MPS I and II groups. Cartilage oligomeric matrix protein, insulin-like growth factor binding protein 7, and β-galactosidase were able to distinguish the severe neurological form of MPS-II from the milder non-neurological form. Protein Heg1 was significantly raised only in MPS-VI. This work describes the discovery of new biomarkers of MPS that represent disease pathology and allows the stratification of MPS-II patients according to disease severity.

Treatability Study Pilot Test Operation Field Photos

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

Li, Jun

Photos in each group are in chronological order as captured: Group I Tank Platform Setup, November 14, 2017; Group II Tank Setup, November 15, 2017; Group III Aboveground Injestion System (AIS) Setup, November 20, 2017; Group IV Chemical Mixing, November 21, 2017; Group V KB-1 Bacteria Injection, November 27, 2017; Group VI Miscellaneous.

Redox and complexation chemistry of the CrVI/CrV-D-glucaric acid system.

PubMed

Mangiameli, María Florencia; González, Juan Carlos; Bellú, Sebastián; Bertoni, Fernando; Sala, Luis F

2014-06-28

When an excess of uronic acid over Cr(VI) is used, the oxidation of D-glucaric acid (Glucar) by Cr(VI) yields D-arabinaric acid, CO2 and Cr(III)-Glucar complex as final redox products. The redox reaction involves the formation of intermediate Cr(IV) and Cr(V) species. The reaction rate increases with [H(+)] and [substrate]. The experimental results indicated that Cr(IV) and Cr(V) are very reactive intermediates since their disappearance rates are much faster than Cr(VI). Cr(IV) and Cr(V) intermediates are involved in fast steps and do not accumulate in the redox reaction of the mixture Cr(VI)-Glucar. Kinetic studies show that the redox reaction between Glucar and Cr(VI) proceeds through a mechanism combining one- and two-electron pathways: Cr(VI) → Cr(IV) → Cr(II) and Cr(VI) → Cr(IV) → Cr(III). After the redox reaction, results show a slow hydrolysis of the Cr(III)-Glucar complex into [Cr(OH2)6](3+). The proposed mechanism is supported by the observation of free radicals, CrO2(2+) (superoxo-Cr(III) ion) and oxo-Cr(V)-Glucar species as reaction intermediates. The continuous-wave electron paramagnetic resonance, CW-EPR, spectra show that five-coordinate oxo-Cr(V) bischelates are formed at pH ≤ 4 with the aldaric acid bound to oxo-Cr(V) through the carboxylate and the α-OH group. A different oxo-Cr(V) species with Glucar was detected at pH 6.0. The high g(iso) value for the last species suggests a mixed coordination species, a five-coordinated oxo-Cr(V) bischelate with one molecule of Glucar acting as a bi-dentate ligand, using the 2-hydroxycarboxylate group, and a second molecule of Glucar with any vic-diolate sites. At pH 7.5 only a very weak EPR signal was observed, which may point to instability of these complexes. This behaviour contrasts with oxo-Cr(V)-uronic species, and must thus be related to the Glucar acyclic structure. In vitro, our studies on the chemistry of oxo-Cr(V)-Glucar complexes can provide information on the nature of the species that are likely to be stabilized in vivo.

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

PubMed

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, 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). Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Oxidation of indometacin by ferrate (VI): kinetics, degradation pathways, and toxicity assessment.

PubMed

Huang, Junlei; Wang, Yahui; Liu, Guoguang; Chen, Ping; Wang, Fengliang; Ma, Jingshuai; Li, Fuhua; Liu, Haijin; Lv, Wenying

2017-04-01

The oxidation of indometacin (IDM) by ferrate(VI) (Fe(VI)) was investigated to determine the reaction kinetics, transformation products, and changes in toxicity. The reaction between IDM and Fe(VI) followed first-order kinetics with respect to each reactant. The apparent second-order rate constants (k app ) decreased from 9.35 to 6.52 M -1  s -1 , as the pH of the solution increased from 7.0 to 10.0. The pH dependence of k app might be well explained by considering the species-specific rate constants of the reactions of IDM with Fe(VI). Detailed product studies using liquid chromatography-tandem mass spectrometry (LC-MS/MS) indicated that the oxidation products were primarily derived from the hydrolysis of amide linkages, the addition of hydroxyl groups, and electrophilic oxidation. The toxicity of the oxidation products was evaluated using the Microtox test, which indicated that transformation products exhibited less toxicity to the Vibrio fischeri bacteria. Quantitative structure-activity relationship (QSAR) analysis calculated by the ecological structure activity relationship (ECOSAR) revealed that all of the identified products exhibited lower acute and chronic toxicity than the parent pharmaceutical for fish, daphnid, and green algae. Furthermore, Fe(VI) was effective in the degradation IDM in water containing carbonate ions or fulvic acid (FA), and in lake water samples; however, higher Fe(VI) dosages would be required to completely remove IDM in lake water in contrast to deionized water.

Calcineurin is not involved in some mitochondrial enzyme adaptations to endurance exercise training in rat skeletal muscle.

PubMed

Terada, Shin; Nakagawa, Hisashi; Nakamura, Yoshio; Muraoka, Isao

2003-09-01

The purpose of this study was to test the hypothesis that calcineurin, a calcium-dependent protein phosphatase recently implicated in the signaling of skeletal muscle hypertrophy and fiber type conversion, is required to induce some mitochondrial enzyme adaptations to endurance exercise training in skeletal muscle. Three- to four-week-old male Sprague-Dawley rats with an initial body weight ranging from 45 to 55 g were used in this study. The rats were randomly assigned to groups injected with either a specific calcineurin inhibitor, cyclosporin A (CsA), (group CI) or vehicle (group VI). CsA was subcutaneously injected into the rats at a rate of 50 mg.kg(-1) body weight per day for 10 days. The CI and VI groups were further assigned to sedentary (SED) or exercise training (EX) groups. In the EX group, the rats were trained for 10 days (90 min.day(-1), approximately 14-20 m.min(-1), 10% grade). The citrate synthase (CS) activities in the soleus and plantaris muscles of the EX group rats were significantly higher than those of the SED group rats ( p<0.001). Furthermore, 3-beta-hydroxyacyl-CoA dehydrogenase (3-HAD) activities in the soleus and plantaris muscles were significantly higher in the EX group rats than in the SED group rats ( p<0.001). However, there were no significant differences in CS and 3-HAD activities between the VI and CI groups. The interactions between CsA injection and exercise training were not statistically significant in any of the parameters. These results may suggest that calcineurin is not involved in some mitochondrial enzyme adaptations to endurance exercise training.

Video Feedback in Key Word Signing Training for Preservice Direct Support Staff.

PubMed

Rombouts, Ellen; Meuris, Kristien; Maes, Bea; De Meyer, Anne-Marie; Zink, Inge

2016-04-01

Research has demonstrated that formal training is essential for professionals to learn key word signing. Yet, the particular didactic strategies have not been studied. Therefore, this study compared the effectiveness of verbal and video feedback in a key word signing training for future direct support staff. Forty-nine future direct support staff were randomly assigned to 1 of 3 key word signing training programs: modeling and verbal feedback (classical method [CM]), additional video feedback (+ViF), and additional video feedback and photo reminder (+ViF/R). Signing accuracy and training acceptability were measured 1 week after and 7 months after training. Participants from the +ViF/R program achieved significantly higher signing accuracy compared with the CM group. Acceptability ratings did not differ between any of the groups. Results suggest that at an equal time investment, the programs containing more training components were more effective. Research on the effect of rehearsal on signing maintenance is warranted.

Use of spectroscopic techniques for uranium(VI)/montmorillonite interaction modeling.

PubMed

Kowal-Fouchard, A; Drot, R; Simoni, E; Ehrhardt, J J

2004-03-01

To experimentally identify both clay sorption sites and sorption equilibria and to understand the retention mechanisms at a molecular level, we have characterized the structure of hexavalent uranium surface complexes resulting from the interaction between the uranyl ions and the surface retention groups of a montmorillonite clay. We have performed laser-induced fluorescence spectroscopy (LIFS) and X-ray photoelectron spectroscopy (XPS) on uranyl ion loaded montmorillonite. These structural results were then compared to those obtained from the study of uranyl ions sorbed onto an alumina and also from U(VI) sorbed on an amorphous silica. This experimental approach allowed for a clear determination of the reactive surface sites of montmorillonite for U(VI) sorption. The lifetime values and the U4f XPS spectra of uranium(VI) sorbed on montmorillonite have shown that this ion is sorbed on both exchange and edge sites. The comparison of U(VI)/clay and U(VI)/oxide systems has determined that the interaction between uranyl ions and montmorillonite edge sites occurs via both [triple bond]AlOH and [triple bond]SiOH surface groups and involves three distinct surface complexes. The surface complexation modeling of the U(VI)/montmorillonite sorption edges was determined using the constant capacitance model and the above experimental constraints. The following equilibria were found to account for the uranyl sorption mechanisms onto montmorillonite for metal concentrations ranged from 10(-6) to 10(-3) M and two ionic strengths (0.1 and 0.5 M): 2[triple bond]XNa + UO2(2+) <==> ([triple bond]X)2UO2 + 2Na+, log K0(exch) = 3.0; [triple bond]Al(OH)2 + UO2(2+) <==> [triple bond]Al(OH)2UO2(2+), log K0(Al) = 14.9; [triple bond]Si(OH)2 + UO2(2+) <==> [triple bond]SiO2UO2 + 2H+, log K0(Si1) = -3.8; and [triple bond]Si(OH)2 + 3UO2(2+) + 5H2O <==> [triple bond]SiO2(UO2)3(OH)5- + 7H+, log K0(Si2) = -20.0.

Retention and release of hexavalent and trivalent chromium by chitosan, olive stone activated carbon, and their blend.

PubMed

Ba, Seydou; Alagui, Abdelhakim; Hajjaji, Mohamed

2018-05-07

Shrimp shells and waste of olive stones were used as feedstock for the preparation of chitosan and activated carbon. The adsorption of Cr VI and Cr III species in aqueous solution by the materials prepared and their blend were studied by using the well-known kinetic and isotherm models, Fourier transform infrared spectroscopy and scanning electron microscope. It was demonstrated that the rates of adsorption were controlled by diffusion inside particles and throughout the liquid film, and adsorption occurred spontaneously (- 26 < ∆G° < - 15 kJ/mol) in the range of 298-333 K, except for that involving Cr III species and activated carbon. The maximum amounts of Cr species retained by the composite (146 mg of Cr VI /g and 33 mg of Cr III /g at 298 K) were three times greater than those of the basic constituents. Adsorption was markedly affected by temperature and pH, and Cr VI species were substantially desorbed in acid mediums, particularly in acetic acid solution. The recovery of Cr III species varied according to the adsorbent and the solution used. The immobilization of Cr VI species (HCrO 4 - and CrO 4 2- ) and Cr III species (Cr(OH) 2 + and Cr 3 (OH) 4 5+ ) by chitosan was accomplished by means of amine moieties and hydroxyls of D-glucosamine units of the biopolymer. The adsorption of Cr VI species on activated carbon involved π electrons of aromatic rings as well as oxygenated sites (C-OH, C=O, C-O-C). In such a condition, Cr VI was partially reduced into Cr III . For the composite, the amino functional groups of chitosan and hydroxyls of both constituents were implicated in the linkage of the biopolymer and activated carbon, and the C-O-H and C-O-C functional groups of chitosan were involved in the retention of Cr VI species. For Cr III species, adsorption occurred preferentially on hydroxyls of the components, and consequently, the chains of the biopolymer recovered some flexibility.

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

PubMed

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.

Non-enzymatic U(VI) interactions with biogenic mackinawite

NASA Astrophysics Data System (ADS)

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.

c-Type Cytochrome-Dependent Formation of U(IV) Nanoparticles by Shewanella oneidensis

PubMed Central

Marshall, Matthew J; Dohnalkova, Alice C; Kennedy, David W; Shi, Liang; Wang, Zheming; Boyanov, Maxim I; Lai, Barry; Kemner, Kenneth M; McLean, Jeffrey S; Reed, Samantha B; Culley, David E; Bailey, Vanessa L; Simonson, Cody J; Saffarini, Daad A; Romine, Margaret F; Zachara, John M

2006-01-01

Modern approaches for bioremediation of radionuclide contaminated environments are based on the ability of microorganisms to effectively catalyze changes in the oxidation states of metals that in turn influence their solubility. Although microbial metal reduction has been identified as an effective means for immobilizing highly-soluble uranium(VI) complexes in situ, the biomolecular mechanisms of U(VI) reduction are not well understood. Here, we show that c-type cytochromes of a dissimilatory metal-reducing bacterium, Shewanella oneidensis MR-1, are essential for the reduction of U(VI) and formation of extracelluar UO 2 nanoparticles. In particular, the outer membrane (OM) decaheme cytochrome MtrC (metal reduction), previously implicated in Mn(IV) and Fe(III) reduction, directly transferred electrons to U(VI). Additionally, deletions of mtrC and/or omcA significantly affected the in vivo U(VI) reduction rate relative to wild-type MR-1. Similar to the wild-type, the mutants accumulated UO 2 nanoparticles extracellularly to high densities in association with an extracellular polymeric substance (EPS). In wild-type cells, this UO 2-EPS matrix exhibited glycocalyx-like properties and contained multiple elements of the OM, polysaccharide, and heme-containing proteins. Using a novel combination of methods including synchrotron-based X-ray fluorescence microscopy and high-resolution immune-electron microscopy, we demonstrate a close association of the extracellular UO 2 nanoparticles with MtrC and OmcA (outer membrane cytochrome). This is the first study to our knowledge to directly localize the OM-associated cytochromes with EPS, which contains biogenic UO 2 nanoparticles. In the environment, such association of UO 2 nanoparticles with biopolymers may exert a strong influence on subsequent behavior including susceptibility to oxidation by O 2 or transport in soils and sediments. PMID:16875436

Chemical and mineralogical composition of the Mongolian rural soils and their uranium sorption behavior.

PubMed

Tserenpil, Sh; Maslov, O D; Norov, N; Liu, Q C; Fillipov, M F; Theng, Benny K G; Belov, A G

2013-04-01

Distribution of uranium (VI) between soil solids and solutions is a key parameter in assessing the risk to the biosphere of disposing uranium-rich waste products from nuclear plants as well as uranium (U) ore mining. Both of these topics have recently been brought to public attention in Mongolia. Regional background levels of soil elements are an important dataset for accessing the actual environmental situation and monitoring pollution levels. Little information, however, is available on background concentrations of various elements in Mongolian soils. Thirteen rural soils were sampled from six provinces in Mongolia, and the concentrations of macro-, micro- and trace elements were measured. The values obtained served as a reference (baseline) for uncontaminated soils. The soils were characterized with slightly acidic to strongly alkaline pH values. With the exception of the sample from a western province, all the soils investigated contained little organic matter. The content of soil elements did not vary widely among geographical regions. The concentration of most micro elements was within the range of worldwide soil values but the value for Zn tended to be moderately higher. The U (VI) sorption into the soils was investigated using the batch technique and the (237)U radionuclide tracer, produced by the photo fission reaction (238)U(γ, n) (237)U at an electron accelerator. The (237)U distribution coefficient (K(d)), derived from the sorption isotherms, was related to solution pH and varying from 9 to 2547 mL g(-1) when the pH ranged between 3 and 7.7. The sorption process was interpreted in terms of the formation of different U (VI) species at given concentrations, calculated using the Speciation program with and without carbonate in the system. The U sorption isotherm displayed two general patterns: one where sorption decreased as solution pH increased, showing a maximum at pH 3, and another pattern revealed an adsorption maximum at pH 5 and then decreased up to pH 7.7 (the final solution pH). The observed decrease in K(d) when solution pH increased from 6 to 8 was consistent with the increased formation of soluble UO(2)(OH)(2) species. A linear negative correlation between lgK(d) and the solution pH was observed similarly to that reported for the soils with a pH ≥ 6. Copyright © 2012 Elsevier Ltd. All rights reserved.

Plasma Fibrinogen in Patients With Bell Palsy.

PubMed

Zhao, Hua; Zhang, Xin; Tang, Yinda; Li, Shiting

2016-10-01

To determine the plasma fibrinogen level in patients with Bell palsy and explore the significances of it in Bell palsy. One hundred five consecutive patients with facial paralysis were divided into 3 groups: group I (Bell palsy), group II (temporal bone fractures), and group III (facial nerve schwannoma). In addition, 22 volunteers were defined as control group. Two milliliters fasting venous blood from elbow was collected, and was evaluated by CA-7000 Full-Automatic Coagulation Analyzer. The plasma fibrinogen concentration was significantly higher in the group of patients with Bell palsy (HB IV-VI) than that in the control group (P <0.05). There was no significant difference between group II and control group (P >0.05); similarly, there was also no marked difference between group III and control group (P >0.05). In group I, the plasma fibrinogen levels became higher with the HB grading increase. The plasma fibrinogen level of HB-VI was highest. Plasma fibrinogen has an important clinical meaning in Bell palsy, which should be used as routine examination items. Defibrinogen in treatment for patients with high plasma fibrinogen content also should be suggested.

A new approach for computing a flood vulnerability index using cluster analysis

NASA Astrophysics Data System (ADS)

Fernandez, Paulo; Mourato, Sandra; Moreira, Madalena; Pereira, Luísa

2016-08-01

A Flood Vulnerability Index (FloodVI) was developed using Principal Component Analysis (PCA) and a new aggregation method based on Cluster Analysis (CA). PCA simplifies a large number of variables into a few uncorrelated factors representing the social, economic, physical and environmental dimensions of vulnerability. CA groups areas that have the same characteristics in terms of vulnerability into vulnerability classes. The grouping of the areas determines their classification contrary to other aggregation methods in which the areas' classification determines their grouping. While other aggregation methods distribute the areas into classes, in an artificial manner, by imposing a certain probability for an area to belong to a certain class, as determined by the assumption that the aggregation measure used is normally distributed, CA does not constrain the distribution of the areas by the classes. FloodVI was designed at the neighbourhood level and was applied to the Portuguese municipality of Vila Nova de Gaia where several flood events have taken place in the recent past. The FloodVI sensitivity was assessed using three different aggregation methods: the sum of component scores, the first component score and the weighted sum of component scores. The results highlight the sensitivity of the FloodVI to different aggregation methods. Both sum of component scores and weighted sum of component scores have shown similar results. The first component score aggregation method classifies almost all areas as having medium vulnerability and finally the results obtained using the CA show a distinct differentiation of the vulnerability where hot spots can be clearly identified. The information provided by records of previous flood events corroborate the results obtained with CA, because the inundated areas with greater damages are those that are identified as high and very high vulnerability areas by CA. This supports the fact that CA provides a reliable FloodVI.

Enhancement of chromate reduction in soils by surface modified biochar.

PubMed

Mandal, Sanchita; Sarkar, Binoy; Bolan, Nanthi; Ok, Yong Sik; Naidu, Ravi

2017-01-15

Chromium (Cr) is one of the common metals present in the soils and may have an extremely deleterious environmental impact depending on its redox state. Among two common forms, trivalent Cr(III) is less toxic than hexavalent Cr(VI) in soils. Carbon (C) based materials including biochar could be used to alleviate Cr toxicity through converting Cr(VI) to Cr(III). Incubation experiments were conducted to examine Cr(VI) reduction in different soils (Soil 1: pH 7.5 and Soil 2: pH 5.5) with three manures from poultry (PM), cow (CM) and sheep (SM), three respective manure-derived biochars (PM biochar (PM-BC), CM biochar (CM-BC) and SM biochar (SM-BC)) and two modified biochars (modified PM-BC (PM-BC-M) and modified SM-BC (SM-BC-M)). Modified biochar was synthesized by incorporating chitosan and zerovalent iron (ZVI) during pyrolysis. Among biochars, highest Cr(VI) reduction was observed with PM-BC application (5%; w/w) (up to 88.12 mg kg -1 ; 45% reduction) in Soil 2 (pH 5.5). The modified biochars enhanced Cr(VI) reduction by 55% (SM-BC-M) compared to manure (29%, SM) and manure-derived biochars (40% reduction, SM-BC). Among the modified biochars, SM-BC-M showed a higher Cr(VI) reduction rate (55%) than PM-BC-M (48%) in Soil 2. Various oxygen-containing surface functional groups such as phenolic, carboxyl, carbonyl, etc. on biochar surface might act as a proton donor for Cr(VI) reduction and subsequent Cr(III) adsorption. This study underpins the immense potential of modified biochar in remediation of Cr(VI) contaminated soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cisplatin plus gemcitabine versus a cisplatin-based triplet versus nonplatinum sequential doublets in advanced non-small-cell lung cancer: a Spanish Lung Cancer Group phase III randomized trial.

PubMed

Alberola, V; Camps, C; Provencio, M; Isla, D; Rosell, R; Vadell, C; Bover, I; Ruiz-Casado, A; Azagra, P; Jiménez, U; González-Larriba, J L; Diz, P; Cardenal, F; Artal, A; Carrato, A; Morales, S; Sanchez, J J; de las Peñas, R; Felip, E; López-Vivanco, G

2003-09-01

To compare the survival benefit obtained with cisplatin plus gemcitabine, a cisplatin-based triplet, and nonplatinum sequential doublets in advanced non-small-cell lung cancer (NSCLC). Stage IIIB to IV NSCLC patients were randomly assigned to receive cisplatin 100 mg/m2 day 1 plus gemcitabine 1,250 mg/m2 days 1 and 8, every 3 weeks for six cycles (CG); cisplatin 100 mg/m2 day 1 plus gemcitabine 1,000 mg/m2 and vinorelbine 25 mg/m2 days 1 and 8, every 3 weeks for six cycles (CGV); or gemcitabine 1,000 mg/m2 plus vinorelbine 30 mg/m2 days 1 and 8, every 3 weeks for three cycles, followed by vinorelbine 30 mg/m2 days 1 and 8 plus ifosfamide 3 g/m2 day 1, every 3 weeks for three cycles (GV-VI). Five hundred fifty-seven patients were assigned to treatment (182 CG, 188 CGV, 187 GV-VI). Response rates were significantly inferior for the nonplatinum sequential doublet (CG, 42%; CGV, 41%; GV-VI, 27%; CG v GV-VI, P =.003). No differences in median survival or time to progression were observed. Toxicity was higher for the triplet: grade 3 to 4 neutropenia (GC, 32%; CGV, 57%; GV-VI, 27%; P <.05); neutropenic fever (CG, 4%; CGV, 19%; GV-VI, 5%; P <.0001); grade 3 to 4 thrombocytopenia (CG, 19%; CGV, 23%; GV-VI, 3%; P =.0001); and grade 3 to 4 emesis (GC, 22%; GCV, 32%; GV-VI, 6%; P <.0001). On the basis of these results, CG remains a standard regimen for first-line treatment of advanced NSCLC.

LabVIEW Task Manager v. 1.10.0

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

Vargo, Timothy D.

LabVIEW Task Manager is a debugging tool for use during code development in the National Instruments (NI) LabVIEW® IDE. While providing a dynamic & big-picture view of running code, an expandable/collapsible tree diagram displays detailed information (both static and dynamic) on all VIs in memory, belonging to a selected project/target. It allows for interacting with single or multiple selected VIs at a time, providing significant benefits while troubleshooting, and has the following features: Look & Feel similar to Windows® Task Manager; Selection of project/target; Lists all VIs in memory, grouped by class/library; Searches for and enumerates clones in memory; DropInmore » VI for including dynamically referenced clones (Clone Beacon); 'Refresh Now' (F5) re-reads all VIs in memory and adds new ones to the tree; Displays VI name, owning class/library, state, path, data size & code size; Displays VI FP Behavior, Reentrant?, Reentrancy Type, Paused? & Highlight?; Sort by any column, including by library name; Filter by item types vi, ctl, and vit/ctt; Filter out vi.lib and global VIs; Tracking of, and ability to toggle, execution highlighting on multiple selected VIs; Tracking of paused VIs with ability to Pause/Resume/TogglePause multiple selected VIs; DropIn VI for pausing on a condition; If a clone initiates a pause, a different pause symbol is used for all clones of that same reentrant original VI; Select multiple VIs and open or close their FPs or BDs; Double Click a VI from the tree to bring the BD (first choice) or FP to front, if already open; and Select multiple top-level VIs and Abort them.« less

Argonne Physics Division - Theory Group

Science.gov Websites

Spectroscopic overlaps Nuclear density Nucleon momenta Workshops 2017 1) VI International Workshop on Non experimental groups at Argonne and at other facilities around the world. A brief overview of our program is

Soviet Military Power

DTIC Science & Technology

1981-09-01

land-based KIROV, the USSR’s first nucler - powered surface warship, symbolizes the increasing strength of the Soviet Armed Forces and the Increasing...53 VI QUEST FOR TECHNOLOGICAL SUPERIORITY ............ 7 VII SOVIET GLOBAL POWER PROJECTION...................83 VIII THE CHALLENGE...military power at a pace that shows no signs of slackening in the future. All elements of the Soviet Armed Forces -the Strategic Rocket Forces, the

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

NASA Astrophysics Data System (ADS)

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

2017-07-01

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

Effects of LED phototherapy on bone defects grafted with MTA, bone morphogenetic proteins, and guided bone regeneration in a rodent model: a description of the bone repair by light microscopy

NASA Astrophysics Data System (ADS)

Pinheiro, Antonio Luiz B.; Aciole, Gilberth T. S.; Soares, Luiz G. P.; Correia, Neandder A.; N. dos Santos, Jean

2011-03-01

We carried out a histological analysis on surgical bone defects grafted or not with MTA, treated or not with LED, BMPs and GBR. We have used several models to assess the effects of laser on bone. Benefits of the isolated or combined use them on bone healing has been suggested. There is no previous report on their association with LED light. 90 rats were divided into 10 groups. On Groups II and I the defect were filled with the clot. On Group II, were further irradiated. On groups III-VI, defect was filled with MTA + Collagen gel (III); animals of group IV were further irradiated. On groups V and VI, the defects filled with the MTA were covered with a membrane. Animals of Group VI were further irradiated. On Groups VII and VIII a pool of BMPs was added to the MTA and was further irradiated. On groups IX and X, the MTA + BMP graft was covered with a membrane. On group X, the defect was further irradiated. LED (λ850 +/- 10nm, 150mW, A= 0.5cm2, 54s, 0.3W/cm2, 16 J/cm2) was applied at 48 h intervals during 15 days. Specimens were taken, processed, cut and stained with H&E and Sirius red and underwent histological analysis. The results showed that MTA seemed not being affected by LED light. However, its use positively affected healing around the graft. It is concluded that MTA is not affected by the LED light due to it characteristics, but beneficial results with LED usage was found.

Selective and Orthogonal Post-Polymerization Modification using Sulfur(VI) Fluoride Exchange (SuFEx) and Copper-Catalyzed Azide–Alkyne Cycloaddition (CuAAC) Reactions

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

Oakdale, James S.; Kwisnek, Luke; Fokin, Valery V.

2016-06-10

Functional polystyrenes and polyacrylamides, containing combinations of fluorosulfate, aromatic silyl ether, and azide side chains, were used as scaffolds to demonstrate the postpolymerization modification capabilities of sulfur(VI) fluoride exchange (SuFEx) and CuAAC chemistries. Fluorescent dyes bearing appropriate functional groups were sequentially attached to the backbone of the copolymers, quantitatively and selectively addressing their reactive partners. Furthermore, this combined SuFEx and CuAAC approach proved to be robust and versatile, allowing for a rare accomplishment: triple orthogonal functionalization of a copolymer under essentially ambient conditions without protecting groups.

A first-principles study of group IV and VI atoms doped blue phosphorene

NASA Astrophysics Data System (ADS)

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.

Thermodynamic analysis of vapor-phase epitaxy of CdTe using a metallic Cd source

NASA Astrophysics Data System (ADS)

Iso, Kenji; Murakami, Hisashi; Koukitu, Akinori

2017-07-01

Thermodynamic analysis of CdTe growth using cost-effective metallic Cd and dialkyl telluride was performed. The major vapor species at source zone in equilibrium were gaseous Cd for the group-II precursor, and Te2 and H2Te for the group-VI precursors. The driving force for the CdTe deposition was still positive even at 650 °C. This indicates that CdTe formation from gaseous Cd can proceed thermodynamically. Furthermore, the calculations showed that CdTe decomposes at higher temperature and increasing the II/VI ratio increases the limit of the growth temperature, which coincides with the experimental results.

Effect of aluminum chloride on blood glucose level and lipid profile in normal, diabetic and treated diabetic rats.

PubMed

Konda, Venugopala Rao; Eerike, Madhavi; Chary, R Prasanth; Arunachalam, Ruckmani; Yeddula, Venkata Ramana; Meti, Vinayak; Devi, T Sobita

2017-01-01

The objectives of the study were to assess evaluate the effects of aluminum chloride (AlCl 3 ) on blood glucose and lipid levels in normal, diabetic, and glibenclamide-treated diabetic rats. Forty-two male Wistar rats were divided into seven groups of six each. Group I was normal control, Groups II and III were given AlCl 3 50 and 100 mg/kg, and Group IV to VII were administered with streptozotocin (STZ) (60 mg/kg) intraperitoneally. Group IV was diabetic control, Group V in addition was given AlCl 3 50 mg/kg, Group VI glibenclamide (10 mg/kg), and Group VII glibenclamide and AlCl 3 (50 mg/kg) per-oral daily for 28 days. Blood glucose and lipid levels were estimated at base line, after diabetes was set in and on the last day of study. Histopathological changes in pancreas, liver, and kidney were studied. No significant change was observed in blood glucose and lipid levels in Group I. Group II and III showed a dose-dependent significant increase in blood glucose was observed. Group V had a reduction in blood glucose but not to the nondiabetic level. Group VI had significant reduction in blood sugar. In Group VII, treated with glibenclamide and AlCl 3 , there was no significant change in blood glucose reduction compared to Group VI. Lipid levels were reduced in groups treated with AlCl 3 and glibenclamide and not in other groups. Gross tissue damage was seen in pancreas in STZ group and in liver and kidney in AlCl 3 groups. AlCl 3 administration in Wistar rats caused in significant hyperglycemia in normal rats, hypoglycemia in diabetic rats, and did not influenced hypoglycemic effect of glibenclamide and in addition, resulted in reduction in lipid levels.

Element speciation during nuclear glass alteration

NASA Astrophysics Data System (ADS)

Galoisy, L.; Calas, G.; Bergeron, B.; Jollivet, P.; Pelegrin, E.

2011-12-01

Assessing the long-term behavior of nuclear glasses implies the prediction of their long-term performance. An important controlling parameter is their evolution during interaction with water under conditions simulating geological repositories. After briefly recalling the major characteristics of the local and medium-range structure of borosilicate glasses of nuclear interest, we will present some structural features of this evolution. Specific structural tools used to determine the local structure of glass surfaces include synchrotron-radiation x-ray absorption spectroscopy with total electron yield detection. The evolution of the structure of glass surface has been determined at the Zr-, Fe-, Si- and Al-K edges and U-LIII edge. During alteration in near- or under-saturated conditions, some elements such as Fe change coordination, as other elements such as Zr only suffer structural modifications in under-saturated conditions. Uranium exhibits a modification of its speciation from an hexa-coordinated U(VI) in the borosilicate glass to an uranyl group in the gel. These structural modifications may explain the chemical dependence of the initial alteration rate and the transition to the residual regime. They also illustrate the molecular-scale origin of the processes at the origin of the glass-to-gel transformation. Eventually, they explain the provisional trapping of U by the alteration gel: the uranium retention factors in the gel depend on the alteration conditions, and thus on the nature of the resulting gel and on the trapping conditions.

Experiment K-6-10. Effects of zero gravity on myofibril protein content and isomyosin distribution in rodent skeletal muscle

NASA Technical Reports Server (NTRS)

Baldwin, K.; Herrick, R.; Oganov, V.

1990-01-01

The purpose of this experiment was to investigate the effects of 12 days of zero gravity (0G) exposure (Cosmos 1887 Biosputnik) on the enzymatic properties, protein content, and isomyosin distribution of the myofibril fraction of the slow-twitch vastus intermedius (VI) and the fast-twitch vastus lateralis (VL) muscles of adult male rats. Measurements were obtained on three experimental groups (n=5 each group) designated as flight-group (FG), vivarium-control (VC), and synchronous-control (SC). Body weight of the FG was significantly lower than the two control groups (p less than 0.05). Compared to the two control groups, VI weight was lower by 23 percent (p less than 0.10); whereas no such reduction was observed for the VL muscle. Myofibril yields (mg protein/g of muscle) in the VI were 35 percent lower in the FG compared to the controls (p less than 0.05); whereas, no such pattern was apparent for the VL muscle. When myofibril yields were expressed on a muscle basis (mg/g x muscle weight), the loss of myofibril protein was more exaggerated and suggests that myofibril protein degradation is an early event in the muscle atrophy response to 0G. Analysis of myosin isoforms indicated that slow-myosin was the primary isoform lost in the calculated degradation of total myosin. No evidence of loss of the fast isomyosins was apparent for either muscle following space flight. Myofibril ATPase activity of the VI was increased in the FG compared to controls, which is consistent with the observation of preferential slow-myosin degradation. These data suggest that muscles containing a high percent of slow-twitch fibers undergo greater degrees of myofibril protein degradation than do muscles containing predominantly fast-twitch fibers in response to a relatively short period of 0G exposure, and the primary target appears to be the slow-myosin molecule.

Theoretical Studies about Adsorption on Silicon Surface

NASA Astrophysics Data System (ADS)

Huang, Yan; Chen, Xiaoshuang; Zhu, Xiao Yan; Duan, He; Zhou, Xiao Hao; Lu, Wei

In this review paper, we address the important research topic of adsorption on the silicon surface. The deposition of single Si ad-species (adatom and ad-dimer) on the p(2×2) reconstructed Si(100) surface has been simulated by the empirical tight-binding method. Using the clean and defective Si surfaces as the deposition substrates, the deposition energies are mapped out around the clean surface, dimer vacancies, steps and kink structures. The binding sites, saddle points and several possible diffusion paths are obtained from the calculated energy. With further analysis of the deposition and diffusion behaviors, the influences of the surface defects can be found. Then, by adopting the first-principle calculations, the adsorptions of the II-VI group elements on the clean and As-passivated Si(211) substrates have been calculated as the example of adsorption on the high-miller-index Si surface.

Oxidation of suspected N-nitrosodimethylamine (NDMA) precursors by ferrate (VI): kinetics and effect on the NDMA formation potential of natural waters.

PubMed

Lee, Changha; Lee, Yunho; Schmidt, Carsten; Yoon, Jeyong; Von Gunten, Urs

2008-01-01

The potential of ferrate (Fe(VI)) oxidation to remove N-nitrosodimethylamine (NDMA) precursors during water treatment was assessed. Apparent second-order rate constants (k(app)) for the reactions of NDMA and its suspected precursors (dimethylamine (DMA) and 7 tertiary amines with DMA functional group) with Fe(VI) were determined in the range of pH 6-12. Four model NDMA precursors (dimethyldithiocarbamate, dimethylaminobenzene, 3-(dimethylaminomethyl)indole and 4-dimethylaminoantipyrine) showed high reactivity toward Fe(VI) with k(app) values at pH 7 between 2.6 x 10(2) and 3.2 x 10(5)M(-1)s(-1). The other NDMA precursors (DMA, trimethylamine, dimethylethanolamine, dimethylformamide) and NDMA had k(app) values ranging from 0.55 to 9.1M(-1)s(-1) at pH 7. In the second part of the study, the NDMA formation potentials (NDMA-FP) of the model NDMA precursors and natural waters were measured with and without pre-oxidation by Fe(VI). For most of the NDMA precursors with the exception of DMA, a significant reduction of the NDMA-FP (>95%) was observed after complete transformation of the NDMA precursor. This result was supported by low yields of DMA from the Fe(VI) oxidation of tertiary amine NDMA precursors. Pre-oxidation of several natural waters (rivers Rhine, Neckar and Pfinz) with a high dose of Fe(VI) (0.38 mM = 21 mg L(-1) as Fe) led to removals of the NDMA-FP of 46-84%. This indicates that the NDMA precursors in these waters have a low reactivity toward Fe(VI) because it has been shown that for fast-reacting NDMA precursors Fe(VI) doses of 20 microM (1.1 mg L(-1) as Fe) are sufficient to completely oxidize the precursors.

36 CFR 7.13 - Yellowstone National Park.

Code of Federal Regulations, 2014 CFR

2014-07-01

... license. Non-commercially guided group means a group of no more than five snowmobiles, including a non... traveling together in Yellowstone National Park on any given day or a non-commercially guided group, which... ascertain which snowmobiles in the park are part of a non-commercially guided group. (vi) Non-commercial...

The interaction between the vastus medialis and vastus intermedius and its influence on the extensor apparatus of the knee joint.

PubMed

Grob, Karl; Manestar, Mirjana; Filgueira, Luis; Kuster, Markus S; Gilbey, Helen; Ackland, Timothy

2018-03-01

Although the vastus medialis (VM) is closely associated with the vastus intermedius (VI), there is a lack of data regarding their functional relationship. The purpose of this study was to investigate the anatomical interaction between the VM and VI with regard to their origins, insertions, innervation and function within the extensor apparatus of the knee joint. Eighteen human cadaveric lower limbs were investigated using macro-dissection techniques. Six limbs were cut transversely in the middle third of the thigh. The mode of origin, insertion and nerve supply of the extensor apparatus of the knee joint were studied. The architecture of the VM and VI was examined in detail, as was their anatomical interaction and connective tissue linkage to the adjacent anatomical structures. The VM originated medially from a broad hammock-like structure. The attachment site of the VM always spanned over a long distance between: (1) patella, (2) rectus femoris tendon and (3) aponeurosis of the VI, with the insertion into the VI being the largest. VM units were inserted twice-once on the anterior and once on the posterior side of the VI. The VI consists of a complex multi-layered structure. The layers of the medial VI aponeurosis fused with the aponeuroses of the tensor vastus intermedius and vastus lateralis. Together, they form the two-layered intermediate layer of the quadriceps tendon. The VM and medial parts of the VI were innervated by the same medial division of the femoral nerve. The VM consists of multiple muscle units inserting into the entire VI. Together, they build a potential functional muscular complex. Therefore, the VM acts as an indirect extensor of the knee joint regulating and adjusting the length of the extensor apparatus throughout the entire range of motion. It is of clinical importance that, besides the VM, substantial parts of the VI directly contribute to the medial pull on the patella and help to maintain medial tracking of the patella during knee extension. The interaction between the VM and VI, with responsibility for the extension of the knee joint and influence on the patellofemoral function, leads readily to an understanding of common clinical problems found at the knee joint as it attempts to meet contradictory demands for both mobility and stability. Surgery or trauma in the anteromedial aspect of the quadriceps muscle group might alter a delicate interplay between the VM and VI. This would affect the extensor apparatus as a whole.

Immunological Development and Cardiovascular Function Are Normal in Annexin VI Null Mutant Mice

PubMed Central

Hawkins, Tim E.; Roes, Jürgen; Rees, Daryl; Monkhouse, Jayne; Moss, Stephen E.

1999-01-01

Annexins are calcium-binding proteins of unknown function but which are implicated in important cellular processes, including anticoagulation, ion flux regulation, calcium homeostasis, and endocytosis. To gain insight into the function of annexin VI, we performed targeted disruption of its gene in mice. Matings between heterozygous mice produced offspring with a normal Mendelian pattern of inheritance, indicating that the loss of annexin VI did not interfere with viability in utero. Mice lacking annexin VI reached sexual maturity at the same age as their normal littermates, and both males and females were fertile. Because of interest in the role of annexin VI in cardiovascular function, we examined heart rate and blood pressure in knockout and wild-type mice and found these to be identical in the two groups. Similarly, the cardiovascular responses of both sets of mice to septic shock were indistinguishable. We also examined components of the immune system and found no differences in thymic, splenic, or bone marrow lymphocyte levels between knockout and wild-type mice. This is the first study of annexin knockout mice, and the lack of a clear phenotype has broad implications for current views of annexin function. PMID:10567528

Changes of Metabolomic Profile in Helianthus annuus under Exposure to Chromium(VI) Studied by capHPLC-ESI-QTOF-MS and MS/MS

PubMed Central

Gonzalez Ibarra, Alan Alexander; Wrobel, Kazimierz; Yanez Barrientos, Eunice; Corrales Escobosa, Alma Rosa; Gutierrez Corona, J. Felix; Enciso Donis, Israel

2017-01-01

The application of capHPLC-ESI-QTOF-MS and MS/MS to study the impact of Cr(VI) on metabolites profile in Helianthus annuus is reported. Germinated seeds were grown hydroponically in the presence of Cr(VI) (25 mgCr/L) and root extracts of the exposed and control plants were analyzed by untargeted metabolomic approach. The main goal was to detect which metabolite groups were mostly affected by Cr(VI) stress; two data analysis tools (ProfileAnalysis, Bruker, and online XCMS) were used under criteria of intensity threshold 5 · 104 cps, fold change ≥ 5, and p ≤ 0.01, yielding precursor ions. Molecular formulas were assigned based on data processing with two computational tools (SIRIUS and MS-Finder); annotation of candidate structures was performed by database search using CSI:FingerID and MS-Finder. Even though ultimate identification has not been achieved, it was demonstrated that secondary metabolism became activated under Cr(VI) stress. Among 42 candidate compounds returned from database search for seven molecular formulas, ten structures corresponded to isocoumarin derivatives and eleven were sesquiterpenes or sesquiterpene lactones; three benzofurans and four glycoside or pyrane derivatives of phenolic compounds were also suggested. To gain further insight on the effect of Cr(VI) in sunflower, isocoumarins and sesquiterpenes were selected as the target compounds for future study. PMID:29359067

U(VI) bioreduction with emulsified vegetable oil as the electron donor--microcosm tests and model development.

PubMed

Tang, Guoping; Wu, Wei-Min; Watson, David B; Parker, Jack C; Schadt, Christopher W; Shi, Xiaoqing; Brooks, Scott C

2013-04-02

We conducted microcosm tests and biogeochemical modeling to study U(VI) reduction in contaminated sediments amended with emulsified vegetable oil (EVO). Indigenous microorganisms in the sediments degraded EVO and stimulated Fe(III), U(VI), and sulfate reduction, and methanogenesis. Acetate concentration peaked in 100-120 days in the EVO microcosms versus 10-20 days in the oleate microcosms, suggesting that triglyceride hydrolysis was a rate-limiting step in EVO degradation and subsequent reactions. Acetate persisted 50 days longer in oleate- and EVO- than in ethanol-amended microcosms, indicating that acetate-utilizing methanogenesis was slower in the oleate and EVO than ethanol microcosms. We developed a comprehensive biogeochemical model to couple EVO hydrolysis, production, and oxidation of long-chain fatty acids (LCFA), glycerol, acetate, and hydrogen, reduction of Fe(III), U(VI) and sulfate, and methanogenesis with growth and decay of multiple functional microbial groups. By estimating EVO, LCFA, and glycerol degradation rate coefficients, and introducing a 100 day lag time for acetoclastic methanogenesis for oleate and EVO microcosms, the model approximately matched observed sulfate, U(VI), and acetate concentrations. Our results confirmed that EVO could stimulate U(VI) bioreduction in sediments and the slow EVO hydrolysis and acetate-utilizing methanogens growth could contribute to longer term bioreduction than simple substrates (e.g., ethanol, acetate, etc.) in the subsurface.

Validation of the Preverbal Visual Assessment (PreViAs) questionnaire.

PubMed

García-Ormaechea, Inés; González, Inmaculada; Duplá, María; Andres, Eva; Pueyo, Victoria

2014-10-01

Visual cognitive integrative functions need to be evaluated by a behavioral assessment, which requires an experienced evaluator. The Preverbal Visual Assessment (PreViAs) questionnaire was designed to evaluate these functions, both in general pediatric population or in children with high risk of visual cognitive problems, through primary caregivers' answers. We aimed to validate the PreViAs questionnaire by comparing caregiver reports with results from a comprehensive clinical protocol. A total of 220 infants (<2 years old) were divided into two groups according to visual development, as determined by the clinical protocol. Their primary caregivers completed the PreViAs questionnaire, which consists of 30 questions related to one or more visual domains: visual attention, visual communication, visual-motor coordination, and visual processing. Questionnaire answers were compared with results of behavioral assessments performed by three pediatric ophthalmologists. Results of the clinical protocol classified 128 infants as having normal visual maturation, and 92 as having abnormal visual maturation. The specificity of PreViAs questionnaire was >80%, and sensitivity was 64%-79%. More than 80% of the infants were correctly classified, and test-retest reliability exceeded 0.9 for all domains. The PreViAs questionnaire is useful to detect abnormal visual maturation in infants from birth to 24months of age. It improves the anamnesis process in infants at risk of visual dysfunctions. Copyright © 2014. Published by Elsevier Ireland Ltd.

Chi-square analysis of the reduction of ATP levels in L-02 hepatocytes by hexavalent chromium.

PubMed

Yuan, Yang; Peng, Li; Gong-Hua, Hu; Lu, Dai; Xia-Li, Zhong; Yu, Zhou; Cai-Gao, Zhong

2012-06-01

This study explored the reduction of adenosine triphosphate (ATP) levels in L-02 hepatocytes by hexavalent chromium (Cr(VI)) using chi-square analysis. Cells were treated with 2, 4, 8, 16, or 32 μM Cr(VI) for 12, 24, or 36 h. Methyl thiazolyl tetrazolium (MTT) experiments and measurements of intracellular ATP levels were performed by spectrophotometry or bioluminescence assays following Cr(VI) treatment. The chi-square test was used to determine the difference between cell survival rate and ATP levels. For the chi-square analysis, the results of the MTT or ATP experiments were transformed into a relative ratio with respect to the control (%). The relative ATP levels increased at 12 h, decreased at 24 h, and increased slightly again at 36 h following 4, 8, 16, 32 μM Cr(VI) treatment, corresponding to a "V-shaped" curve. Furthermore, the results of the chi-square analysis demonstrated a significant difference of the ATP level in the 32-μM Cr(VI) group (P < 0.05). The results suggest that the chi-square test can be applied to analyze the interference effects of Cr(VI) on ATP levels in L-02 hepatocytes. The decreased ATP levels at 24 h indicated disruption of mitochondrial energy metabolism and the slight increase of ATP levels at 36 h indicated partial recovery of mitochondrial function or activated glycolysis in L-02 hepatocytes.

Composite Measures of Individual and Area-Level Socio-Economic Status Are Associated with Visual Impairment in Singapore

PubMed Central

Wah, Win; Earnest, Arul; Sabanayagam, Charumathi; Cheng, Ching-Yu; Ong, Marcus Eng Hock; Wong, Tien Y.; Lamoureux, Ecosse L.

2015-01-01

Purpose To investigate the independent relationship of individual- and area-level socio-economic status (SES) with the presence and severity of visual impairment (VI) in an Asian population. Methods Cross-sectional data from 9993 Chinese, Malay and Indian adults aged 40–80 years who participated in the Singapore Epidemiology of eye Diseases (2004–2011) in Singapore. Based on the presenting visual acuity (PVA) in the better-seeing eye, VI was categorized into normal vision (logMAR≤0.30), low vision (logMAR>0.30<1.00), and blindness (logMAR≥1.00). Any VI was defined as low vision/blindness in the PVA of better-seeing eye. Individual-level low-SES was defined as a composite of primary-level education, monthly income<2000 SGD and residing in 1 or 2-room public apartment. An area-level SES was assessed using a socio-economic disadvantage index (SEDI), created using 12 variables from the 2010 Singapore census. A high SEDI score indicates a relatively poor SES. Associations between SES measures and presence and severity of VI were examined using multi-level, mixed-effects logistic and multinomial regression models. Results The age-adjusted prevalence of any VI was 19.62% (low vision = 19%, blindness = 0.62%). Both individual- and area-level SES were positively associated with any VI and low vision after adjusting for confounders. The odds ratio (95% confidence interval) of any VI was 2.11(1.88–2.37) for low-SES and 1.07(1.02–1.13) per 1 standard deviation increase in SEDI. When stratified by unilateral/bilateral categories, while low SES showed significant associations with all categories, SEDI showed a significant association with bilateral low vision only. The association between low SES and any VI remained significant among all age, gender and ethnic sub-groups. Although a consistent positive association was observed between area-level SEDI and any VI, the associations were significant among participants aged 40–65 years and male. Conclusion In this community-based sample of Asian adults, both individual- and area-level SES were independently associated with the presence and severity of VI. PMID:26555141

A genomic island in Vibrio cholerae with VPI-1 site-specific recombination characteristics contains CRISPR-Cas and type VI secretion modules

PubMed Central

Labbate, Maurizio; Orata, Fabini D.; Petty, Nicola K.; Jayatilleke, Nathasha D.; King, William L.; Kirchberger, Paul C.; Allen, Chris; Mann, Gulay; Mutreja, Ankur; Thomson, Nicholas R.; Boucher, Yan; Charles, Ian G.

2016-01-01

Cholera is a devastating diarrhoeal disease caused by certain strains of serogroup O1/O139 Vibrio cholerae. Mobile genetic elements such as genomic islands (GIs) have been pivotal in the evolution of O1/O139 V. cholerae. Perhaps the most important GI involved in cholera disease is the V. cholerae pathogenicity island 1 (VPI-1). This GI contains the toxin-coregulated pilus (TCP) gene cluster that is necessary for colonization of the human intestine as well as being the receptor for infection by the cholera-toxin bearing CTX phage. In this study, we report a GI (designated GIVchS12) from a non-O1/O139 strain of V. cholerae that is present in the same chromosomal location as VPI-1, contains an integrase gene with 94% nucleotide and 100% protein identity to the VPI-1 integrase, and attachment (att) sites 100% identical to those found in VPI-1. However, instead of TCP and the other accessory genes present in VPI-1, GIVchS12 contains a CRISPR-Cas element and a type VI secretion system (T6SS). GIs similar to GIVchS12 were identified in other V. cholerae genomes, also containing CRISPR-Cas elements and/or T6SS’s. This study highlights the diversity of GIs circulating in natural V. cholerae populations and identifies GIs with VPI-1 recombination characteristics as a propagator of CRISPR-Cas and T6SS modules. PMID:27845364

[Determination of fumes and their elements from flux cored arc welding].

PubMed

Matczak, Wanda; Przybylska-Stanisławska, Magdalena

2004-01-01

The aim of this work was to assay the concentration levels and composition of welding fumes, released during flux cored arc welding, to assess exposure of welders. Concentrations and welding fume components, such as iron, manganese, chromium (including the soluble and chromium VI), nickel, copper, calcium, aluminium, barium, and fluorides (including hydrogen fluoride) were determined in the air of six industrial plants (shipyards, mechanical engineering plants and a power station) at the breathing zones of the welders who used 10 types of wires during flux cored arc welding. The following determination methods were used: gravimetry (fumes), AAS (metals), and spectrophotometry (chromium VI, fluorides--including hydrogen fluoride). The results made it possible to determine the relationship between concentrations of welding fume and its elements, and to assess worker's exposure. Time weighted average concentrations of the welding fumes and its elements at the worker's breathing zone were: mg/m3: dust 0.2-24.3; Fe 0.2-6.7; Mn 0.01-1.8; Cr 0.004-0.5 (mainly Cr III); Ca 0.004-2.5; Ni < or = 0.004; Cu < 0.002-0.05; Al < 0.14-0.4; Ba < 0.14; F- 0.07-0.43. The welders using some types of flux cored welding wires worked in conditions harmful to their health owing to the considerably exceeded TLV value for fume and MAC values for manganese, and occasional slightly excessive MAC values for calcium and iron.

Diverse metal reduction and nano- mineral formation by metal-reducing bacteria enriched from inter-tidal flat sediments

NASA Astrophysics Data System (ADS)

Kim, Y.; Park, B.; Seo, H.; Roh, Y.

2009-12-01

Dissimilatory metal-reducing bacteria utilize diverse metal oxides as electron acceptors and couple this microbial metal reduciton to growth. However, the microbe-metal interactions playing important roles in the metal geochemistry and organic matter degradation in the tidal flat sediments have not been uncovered enough to employ in various environmental and industrial applications. The objective of this study was to examine biomineralization and bioremediation by the facultative metal-reducing bacteria isolated from the inter-tidal flat sediments in southwestern of Korea. 16S-rRNA analysis showed bacterial consortium mainly consists of genus of Clostridium sp. The enriched bacteria were capable of reducing diverse metals such as iron oxide, maganese oxide, Cr(VI) and Se(VI) during glucose fermentation process at room temperature. The bacteria reduced highly toxic and reactive elements such as Cr(VI) and Se(VI) to Cr(III) and Se(0). The results showed that microbial processes induced transformation from toxic states of heavy metals to less toxic and mobile states in natural environments. Andthe bacteria also reduced iron oxyhydroxide such as ferrihydrite and akaganeite (β-FeOOH) and formed nanometer-sized magnetite (Fe3O4). This study indicates microbial processes not only can be used for bioremediation of inorganic contaminants existing in the marine environments, but also form the magnetite nanoparticles which are exhibit superparamagnetic properties that can be useful for relevant medical and industrial applications.

Toxic metals biosorption by Jatropha curcas deoiled cake: equilibrium and kinetic studies.

PubMed

Rawat, Anand P; Rawat, Monica; Rai, J P N

2013-08-01

The equilibrium sorption of Cr(VI) and Cu(II) from aqueous solution using Jatropha curcas deoiled cake, has been studied with respect to adsorbent dosage, contact time, pH, and initial metal concentration in batch mode experiments. Removal of Cu(II) by deoiled cake was greater than that of Cr(VI). The adsorbent chemical characteristics, studied by Fourier transform-infrared analysis, suggested that the presence of Cr(VI) and Cu(II) in the biomass influenced the bands corresponding to hydroxyl and carboxyl groups. Desorption studies revealed that maximum metals recovery was achieved by HNO3 followed by CH3COOH and HCl. The Freundlich isotherm model showed good fit to the equilibrium adsorption data. The adsorption kinetics followed the pseudo-second-order model, which provided the best correlation for the biosorption process, and suggested that J. curcas deoiled cake can be used as an efficient biosorbent over other commonly used sorbents for decontamination of Cr(VI)- and Cu(II)-containing wastewater.

Complete genome sequence of the chromate-reducing bacterium Thermoanaerobacter thermohydrosulfuricus strain BSB-33

DOE PAGES

Bhattacharya, Pamela; Barnebey, Adam; Zemla, Marcin; ...

2015-10-05

Thermoanaerobacter thermohydrosulfuricus BSB-33 is a thermophilic gram positive obligate anaerobe isolated from a hot spring in West Bengal, India. Unlike other T. thermohydrosulfuricus strains, BSB-33 is able to anaerobically reduce Fe(III) and Cr(VI) optimally at 60 °C. BSB-33 is the first Cr(VI) reducing T. thermohydrosulfuricus genome sequenced and of particular interest for bioremediation of environmental chromium contaminations. Here we discuss features of T. thermohydrosulfuricus BSB-33 and the unique genetic elements that may account for the peculiar metal reducing properties of this organism. The T. thermohydrosulfuricus BSB-33 genome comprises 2597606 bp encoding 2581 protein genes, 12 rRNA, 193 pseudogenes and hasmore » a G + C content of 34.20 %. Lastly, putative chromate reductases were identified by comparative analyses with other Thermoanaerobacter and chromate-reducing bacteria.« less

Catalytic coal hydroliquefaction process

DOEpatents

Garg, Diwakar

1984-01-01

A process is described for the liquefaction of coal in a hydrogen donor solvent in the presence of hydrogen and a co-catalyst combination of iron and a Group VI or Group VIII non-ferrous metal or compounds of the catalysts.

First Report of ‘Candidatus Phytoplasma trifolii’-Related Strain of 16SrVI-A Phytoplasma Subgroup, Associated with Elm Yellows Disease in American Elm ( Ulmus americana L.) in Ohio, U.S.A

Treesearch

C.E. Flower; N. Hayes-Plazolles; J.M. Slavicek; C. Rosa

2018-01-01

During the investigation of the sudden and early onset of yellowing and mortality of American elm (Ulmus americana L.) trees at the USDA Forest Service Northern Research Station in Delaware, OH, a phytoplasma of the clover proliferation group (16SrVI) was detected as the putative causal agent of the disease outbreak.

U(VI) biosorption by bi-functionalized Pseudomonas putida @ chitosan bead: Modeling and optimization using RSM.

PubMed

Sohbatzadeh, Hozhabr; Keshtkar, Ali Reza; Safdari, Jaber; Fatemi, Faezeh

2016-08-01

In this work, Pseudomonas putida cells immobilized into chitosan beads (PICB) were synthesized to investigate the impact of microorganism entrapment on biosorption capacity of prepared biosorbent for U(VI) biosorption from aqueous solutions. Response Surface Methodology (RSM) based on Central Composite Design (CCD) was utilized to evaluate the performance of the PICB in comparison with chitosan beads (CB) under batch mode. Performing experiments under optimal condition sets viz. pH 5, initial U(VI) concentration 500mg/L, biosorbent dosage 0.4g/L and 20wt.% bacterial cells showed that the observed biosorption capacity enhanced by 1.27 times from 398mg/g (CB) to 504mg/g (PICB) that confirmed the effectiveness of cells immobilization process. FTIR and potentiometric titration were then utilized to characterize the prepared biosorbents. While the dominant functional group in the binding process was NH3(+) (4.78meq/g) in the CB, the functional groups of NH3(+), NH2, OH, COOH (6.00meq/g) were responsible for the PICB. The equilibrium and kinetic studies revealed that the Langmuir isotherm model and the pseudo-second-order kinetic model were in better fitness with the CB and PICB experimental data. In conclusion, the present study indicated that the PICB could be a suitable biosorbent for uranium (VI) biosorption from aqueous solutions. Copyright © 2016 Elsevier B.V. All rights reserved.

Interaction of aerobic soil bacteria with plutonium(VI)

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

Panak, Petra J.; Nitsche, Heino

2000-08-22

We studied the interaction of Pu(VI) with Pseudomonas stutzeri ATCC 17588 and Bacillus sphaericus ATCC 14577, representatives of the main aerobic groups of soil bacteria present in the upper soil layers. The accumulation studies have shown that these soil bacteria accumulate high amounts of Pu(VI). The sorption efficiency toward Pu(VI) decreased with increasing biomass concentration due to increased agglomeration of the bacteria resulting in a decreased total surface area and number of available complexing groups. Spores of Bacillus sphaericus showed a higher biosorption than the vegetative cells at low biomass concentration which decreased significantly with increasing biomass concentration. At highermore » biomass concentrations (> 0.7 g/L), the vegetative cells of both strains and the spores of B. sphaericus showed comparable sorption efficiencies. Investigations on the pH dependency of the biosorption and extraction studies with 0.01 M EDTA solution have shown that the biosorption of plutonium is a reversible process and the plutonium is bound by surface complexation. Optical absorption spectroscopy showed that one third of the initially present Pu(VI) was reduced to Pu(V) after 24 hours. Kinetic studies and solvent extraction to separate different oxidation states of Pu after contact with the biomass provided further information on the yield and the kinetics of the bacteria-mediated reduction. Long-term studies showed that also 16% of Pu(IV) was formed after one month. The comparison of the amount of Pu(IV) formed during that time period with literature data of the Pu(V) disproportionation, indicated that the Pu(IV) seemed to be rather the result of the disproportionation of the formed Pu(V) than of a further microbial reduction.« less

Modeling Interferometric Structures with Birefringent Elements: A Linear Vector-Space Formalism

DTIC Science & Technology

2013-11-12

Annapolis, Maryland ViNceNt J. Urick FraNk BUcholtz Photonics Technology Branch Optical Sciences Division i REPORT DOCUMENTATION PAGE Form...a Linear Vector-Space Formalism Nicholas J. Frigo,1 Vincent J. Urick , and Frank Bucholtz Naval Research Laboratory, Code 5650 4555 Overlook Avenue, SW...Annapolis, MD Unclassified Unlimited Unclassified Unlimited Unclassified Unlimited Unclassified Unlimited 29 Vincent J. Urick (202) 767-9352 Coupled mode

A new classification of a preovulatory oocyte maturation stage suitable for the synchronization of ovulation in controlled reproduction of Eurasian perch Perca fluviatilis L.

PubMed

Zarski, Daniel; Bokor, Zoltán; Kotrik, László; Urbanyi, Béla; Horváth, Akos; Targońska, Katarzyna; Krejszeff, Sławomir; Palińska, Katarzyna; Kucharczyk, Dariusz

2011-11-01

To improve controlled reproduction of Eurasian perch Perca fluviatilis, the criteria for the evaluation of final oocyte maturation stages were revised. The new classification covers six preovulatory maturational stages (I -VI) from the end of vitellogenesis to germinal vesicle breakdown (GVBD) and was based on macroscopic changes of preovulatory oocytes (position of the germinal vesicle, GVBD, oil droplets coalescence). The observation was performed during out-of-season artificial reproduction with the use of a single hCG injection (500 IU/kg). The classification was subsequently verified with the controlled reproduction of wild female perch with the use of hormonal stimulation (500 IU hCG/kg of body weight at 12°C). The females were at different maturational stages and constituted respective experimental groups (I-VI). During the experiment, ovulation appeared to be considerably synchronized within particular groups. Statistical differences in latency time (time between hormonal treatment and ovulation) were found between experimental groups (mean latency time: 110, 92, 68, 49, 29 and 18 h in groups representing VI, V, IV, III, II and I stage of the proposed classification, respectively). The proposed classification and the results presented in the study allowed for effective synchronisation of ovulation. The use of our new oocyte maturation classification may positively influence the effectiveness of Eurasian perch production.

Development of a 35-MHz piezo-composite ultrasound array for medical imaging.

PubMed

Cannata, Jonathan M; Williams, Jay A; Zhou, Qifa; Ritter, Timothy A; Shung, K Kirk

2006-01-01

This paper discusses the development of a 64-element 35-MHz composite ultrasonic array. This array was designed primarily for ocular imaging applications, and features 2-2 composite elements mechanically diced out of a fine-grain high-density Navy Type VI ceramic. Array elements were spaced at a 50-micron pitch, interconnected via a custom flexible circuit and matched to the 50-ohm system electronics via a 75-ohm transmission line coaxial cable. Elevation focusing was achieved using a cylindrically shaped epoxy lens. One functional 64-element array was fabricated and tested. Bandwidths averaging 55%, 23-dB insertion loss, and crosstalk less than -24 dB were measured. An image of a tungsten wire target phantom was acquired using a synthetic aperture reconstruction algorithm. The results from this imaging test demonstrate resolution exceeding 50 microm axially and 100 microm laterally.

A Floating Node Method for the Modelling of Discontinuities Within a Finite Element

NASA Technical Reports Server (NTRS)

Pinho, Silvestre T.; Chen, B. Y.; DeCarvalho, Nelson V.; Baiz, P. M.; Tay, T. E.

2013-01-01

This paper focuses on the accurate numerical representation of complex networks of evolving discontinuities in solids, with particular emphasis on cracks. The limitation of the standard finite element method (FEM) in approximating discontinuous solutions has motivated the development of re-meshing, smeared crack models, the eXtended Finite Element Method (XFEM) and the Phantom Node Method (PNM). We propose a new method which has some similarities to the PNM, but crucially: (i) does not introduce an error on the crack geometry when mapping to natural coordinates; (ii) does not require numerical integration over only part of a domain; (iii) can incorporate weak discontinuities and cohesive cracks more readily; (iv) is ideally suited for the representation of multiple and complex networks of (weak, strong and cohesive) discontinuities; (v) leads to the same solution as a finite element mesh where the discontinuity is represented explicitly; and (vi) is conceptually simpler than the PNM.

Synthesis, spectroscopic, coordination and biological activities of some organometallic complexes derived from thio-Schiff base ligands

NASA Astrophysics Data System (ADS)

Abou-Hussein, Azza A.; Linert, Wolfgang

2014-01-01

Two series of mono- and binuclear complexes cyclic or acyclic thio-ferocine Schiff base ligands, derived from the condensation of 2-aminobenzenthiol (L) with monoacetyl ferrocene in the molar ratio 1:1 or in the molar ratio 1:2 for diacetyl ferocine have been prepared. The condensation reactions yield the corresponding Schiff Base ligands, HLa-Maf and H2Lb-Daf. The chelation of the ligands to metal ions occurs through the sulfur of the thiol group as well as the nitrogen atoms of the azomethine group of the ligands. HLa-Maf acts as monobasic bidentate or dibasic tetradentate, while H2Lb-Daf behaves as twice negatively cargend tetradentate ligand. The structures of these ligands were elucidated by elemental analysis, infrared, ultraviolet-visible spectra, as well as 1H NMR spectra. Reactions of the Schiff bases ligands with ruthenium(III), oxovanadium(IV) and dioxouranium(VI) afforded the corresponding transition metal complexes. The properties of the newly prepared complexes were analyse by elemental analyses, infrared, electronic spectra, 1H NMR as well as the magnetic susceptibility and conductivity measurement. The metal complexes exhibits different geometrical arrangements such as octahedral and square pyramidal coordination. Schiff base ligands and their metal complexes were tested against two pathogenic bacteria as Gram-positive and Gram-negative bacteria as well as one kind of fungi to study their biological activity. All the complexes exhibit antibacterial and antifungal activities against these organisms.

Investigation of the Finite Element Software Packages at KSC

NASA Technical Reports Server (NTRS)

Lu, Chu-Ho

1991-01-01

The useful and powerful features of NASTRAN and three real world problems for the testing of the capabilities of different NASTRAN versions are discussed. The test problems involve direct transient analysis, nonlinear analysis, and static analysis. The experiences in using graphics software packages are also discussed. It was found that MSC/XL can be more useful if it can be improved to generate picture files of the analysis results and to extend its capabilities to support finite element codes other than MSC/NASTRAN. It was found that the current version of SDRC/I-DEAS (version VI) may have bugs in the module 'Data Loader'.

Research Staff | Photovoltaic Research | NREL

Science.gov Websites

-7511 Name Position Email Phone Al-Jassim, Mowafak Group Research Manager III-Materials Science , Teresa Acting Group Manager Teresa.Barnes@nrel.gov 303-384-6682 Beard, Matt Researcher VI-Chemistry @nrel.gov 303-384-7611 Blackburn, Jeffrey Group Research Manager III-Materials Science Jeffrey.Blackburn

49 CFR 535.5 - Standards.

Code of Federal Regulations, 2013 CFR

2013-10-01

... configuration. (A) A manufacturer may group together subconfigurations that have the same test weight (ETW... section apply for vehicles complying in model year 2013. If some test groups are certified by EPA after... production that occurs after all test groups are certified in accordance with 40 CFR 1037.150 (a)(2). (vi...

49 CFR 535.5 - Standards.

Code of Federal Regulations, 2014 CFR

2014-10-01

... configuration. (A) A manufacturer may group together subconfigurations that have the same test weight (ETW... section apply for vehicles complying in model year 2013. If some test groups are certified by EPA after... production that occurs after all test groups are certified in accordance with 40 CFR 1037.150 (a)(2). (vi...

Fast Photo-detection in Phototransistors based on Group III-VI Layered Materials.

NASA Astrophysics Data System (ADS)

Patil, Prasanna; Ghosh, Sujoy; Wasala, Milinda; Lei, Sidong; Vajtai, Robert; Ajayan, Pulickel; Talapatra, Saikat

Response time of a photo detector is one of the crucial aspect of photo-detection. Recently it has been shown that direct band gap of few layered group III-VI materials helps in increased absorption of light thereby enhancing the photo responsive properties of these materials. Ternary system of Copper Indium Selenide has been extensively used in optoelectronics industry and it is expected that 2D layered structure of Copper Indium Selenide will be a key component of future optoelectronics devices based on 2D materials. Here we report fast photo detection in few layers of Copper Indium Selenide (CuIn7Se11) phototransistor. Few-layers of CuIn7Se11 flakes were exfoliated from crystals grown using chemical vapor transport technique. Our photo response characterization indicates responsivity of 104 mA/W with external quantum efficiency exceeding 103. We have found response time of few μs which is one of the fastest response among photodetectors based on 2D materials. We also found specific detectivity of 1012 Jones which is an order higher than conventional photodetectors. A comparison between response times of various layered group III-VI materials will be presented and discussed. This work is supported by the U.S. Army Research Office through a MURI Grant # W911NF-11-1-0362.

Diffractometric measurement of the temperature dependence of piezoelectric tensor in GMO monocrystal

NASA Astrophysics Data System (ADS)

Breczko, Teodor; Lempaszek, Andrzej

2007-04-01

Functional materials, of which an example is ferroelectric, ferroelastic monocrystal of molybdate (III) gadolinium (VI), are often used in the micro-motor operators (micro-servo motors) working in changeable environment conditions. Most frequently this change refers to temperature. That is why the important practical problem is the precise measurement of the value of piezoelectric tensor elements in dependence on the temperature of a particular monocrystal. In the presented article for this kind of measurements, the use of X-ray diffractometer has been shown. The advantage of the method presented is that, apart from precise dependence measurement between the temperature of a monocrystal and the value of piezoelectric tensor elements, it enables synchronous measurement of the value of thermal expansion tensor elements for a monocrystal.

Development and testing of the VITAMIN-B7/BUGLE-B7 coupled neutron-gamma multigroup cross-section libraries

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

Risner, J.M.; Wiarda, D.; Miller, T.M.

2011-07-01

The U.S. Nuclear Regulatory Commission's Regulatory Guide 1.190 states that calculational methods used to estimate reactor pressure vessel (RPV) fluence should use the latest version of the evaluated nuclear data file (ENDF). The VITAMIN-B6 fine-group library and BUGLE-96 broad-group library, which are widely used for RPV fluence calculations, were generated using ENDF/B-VI.3 data, which was the most current data when Regulatory Guide 1.190 was issued. We have developed new fine-group (VITAMIN-B7) and broad-group (BUGLE-B7) libraries based on ENDF/B-VII.0. These new libraries, which were processed using the AMPX code system, maintain the same group structures as the VITAMIN-B6 and BUGLE-96 libraries.more » Verification and validation of the new libraries were accomplished using diagnostic checks in AMPX, 'unit tests' for each element in VITAMIN-B7, and a diverse set of benchmark experiments including critical evaluations for fast and thermal systems, a set of experimental benchmarks that are used for SCALE regression tests, and three RPV fluence benchmarks. The benchmark evaluation results demonstrate that VITAMIN-B7 and BUGLE-B7 are appropriate for use in RPV fluence calculations and meet the calculational uncertainty criterion in Regulatory Guide 1.190. (authors)« less

Development and Testing of the VITAMIN-B7/BUGLE-B7 Coupled Neutron-Gamma Multigroup Cross-Section Libraries

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

Risner, Joel M; Wiarda, Dorothea; Miller, Thomas Martin

2011-01-01

The U.S. Nuclear Regulatory Commission s Regulatory Guide 1.190 states that calculational methods used to estimate reactor pressure vessel (RPV) fluence should use the latest version of the Evaluated Nuclear Data File (ENDF). The VITAMIN-B6 fine-group library and BUGLE-96 broad-group library, which are widely used for RPV fluence calculations, were generated using ENDF/B-VI data, which was the most current data when Regulatory Guide 1.190 was issued. We have developed new fine-group (VITAMIN-B7) and broad-group (BUGLE-B7) libraries based on ENDF/B-VII. These new libraries, which were processed using the AMPX code system, maintain the same group structures as the VITAMIN-B6 and BUGLE-96more » libraries. Verification and validation of the new libraries was accomplished using diagnostic checks in AMPX, unit tests for each element in VITAMIN-B7, and a diverse set of benchmark experiments including critical evaluations for fast and thermal systems, a set of experimental benchmarks that are used for SCALE regression tests, and three RPV fluence benchmarks. The benchmark evaluation results demonstrate that VITAMIN-B7 and BUGLE-B7 are appropriate for use in LWR shielding applications, and meet the calculational uncertainty criterion in Regulatory Guide 1.190.« less

Safety and immunogenicity of a Vi polysaccharide-tetanus toxoid conjugate vaccine (Typbar-TCV) in healthy infants, children, and adults in typhoid endemic areas: a multicenter, 2-cohort, open-label, double-blind, randomized controlled phase 3 study.

PubMed

Mohan, Vadrevu Krishna; Varanasi, Vineeth; Singh, Anit; Pasetti, Marcela F; Levine, Myron M; Venkatesan, Ramasamy; Ella, Krishna M

2015-08-01

Enteric fever caused by Salmonella Typhi remains a major public health problem in developing countries. Typbar-TCV is a single-dose typhoid Vi polysaccharide-tetanus toxoid conjugate vaccine for persons ≥6 months of age. Six hundred fifty-four healthy subjects aged 2-45 years enrolled in a double-blind, randomized controlled trial (RCT) received a single dose of Typbar-TCV or comparator "Vi polysaccharide" (Typbar), and 327 healthy subjects aged 6-23 months received a single dose of Typbar-TCV in an open-label trial (OLT); both received single- or multidose presentations from different lots. After 2 years, subsets in each group received a booster dose. The primary objective included analysis of geometric mean titer (GMTs) and 4-fold rise of anti-Vi serum immunoglobulin G (IgG) enzyme-linked immunosorbent assay titers over baseline (seroconversion [SCN]) 42 days after immunization. Typbar-TCV recipients in the RCT attained higher anti-Vi IgG GMTs 42 days after immunization (SCN, 97%; GMT, 1293 [95% confidence interval {CI}, 1153-1449]) than recipients of Typbar (SCN, 93%; GMT, 411 [95% CI, 359-471]) (P < .001). Typbar-TCV was highly immunogenic in the OLT (SCN, 98%; GMT, 1937 [95% CI, 1785-2103]). Two years after vaccination, anti-Vi titers remained higher in Typbar-TCV subjects (GMT, 82 [95% CI, 73-92]); and exhibited higher avidity (geometric mean avidity index [GMAI], 60%) than in Typbar recipients (GMT, 46 [95% CI, 40-53]; GMAI 46%) in the RCT (P < .001). OLT Typbar-TCV recipients achieved GMT of 48 (95% CI, 42-55) and GMAI of 57%. Typbar-TCV induced multiple IgG subclasses and strong booster responses in all ages. No serious vaccine-attributable adverse events were observed. Single-dose Typbar-TCV is well tolerated and induces robust and long-lasting serum anti-Vi IgG across age groups. CTRI/2011/08/001957, CTRI/2014/01/004341. © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Influence of Er:YAG laser irradiation distance on the bond strength of a restorative system to enamel.

PubMed

Chimello-Sousa, Daniela Thomazatti; de Souza, Aline Evangelista; Chinelatti, Michelle Alexandra; Pécora, Jesus Djalma; Palma-Dibb, Regina Guenka; Milori Corona, Silmara Aparecida

2006-03-01

The aim of the present study was to investigate in vitro the effect of Er:YAG laser on bonding to enamel, varying the irradiation distance. Tensile bond strength of an adhesive restorative system to non-irradiated and irradiated enamel surfaces was evaluated. Thirty caries-free human third molars were sectioned in mesio-distal direction and embedded in acrylic resin. Enamel was flattened, and a 3-mm-diameter bonding area was demarcated. Specimens were randomly assigned into six groups: groups I-V were treated with the Er:YAG laser (80 mJ/2 Hz), varying the irradiation distance (11, 12 mm-focused, 14, 16 and 17 mm, respectively), followed by 35% phosphoric acid etching. Control group (VI) received treatment with phosphoric acid alone. Single Bond adhesive system was applied on the conditioned enamel, and composite resin cones, bonded to enamel, were fabricated with Z250. After storage, samples were tested in tensile to failure (50 kgf and 0.5 mm/min). Means in MPa were: I-9.67 (+/-3.44); II-13.29 (+/-2.65); III-13.33 (+/-2.22); IV-14.87 (+/-3.58); V-16.43 (+/-4.52); VI-22.90 (+/-3.03). ANOVA and Tukey test revealed statistically significant decrease of bond strength in group I (P < 0.05). Groups II-IV presented similar results, as did groups IV and V. Control group (VI) yielded the best overall performance (P < 0.05). Er:YAG laser irradiation adversely affected adhesion to enamel. However, bond strength was influenced by the irradiation distance, thus being stronger with the increase of distance to the target tissue.

The role of carbonic anhydrase VI in bitter taste perception: evidence from the Car6−/− mouse model

PubMed Central

2014-01-01

Background Carbonic anhydrase VI (CA VI) is a secretory isozyme of the α-CA gene family. It is highly expressed in the salivary and mammary glands and secreted into saliva and milk. Although CA VI was first described as a gustatory protein, its exact functional roles have remained enigmatic. Interestingly, polymorphism of the CA6 gene was recently linked to bitter taste perception in humans. In this study, we compared the preference of Car6−/− and wild-type mice for different taste modalities in an IntelliCage monitoring environment. Morphologies of taste buds, tongue papillae, and von Ebner’s glands were evaluated by light microscopy. Cell proliferation and rate of apoptosis in tongue specimens were examined by Ki67 immunostaining and fluorescent DNA fragmentation staining, respectively. Results The behavioral follow up of the mice in an IntelliCage system revealed that Car6−/− mice preferred 3 μM quinine (bitter) solution, whereas wild type mice preferred water. When the quinine concentration increased, both groups preferentially selected water. Histological analysis, Ki67 immunostaining and detection of apoptosis did not reveal any significant changes between tongue specimens of the knockout and wild type mice. Conclusions Our knockout mouse model confirms that CA VI is involved in bitter taste perception. CA VI may be one of the factors which contribute to avoidance of bitter, potentially harmful, substances. PMID:25134447

Intracellular versus extracellular accumulation of Hexavalent chromium reduction products by Geobacter sulfurreducens PCA.

PubMed

Gong, Yufeng; Werth, Charles J; He, Yaxue; Su, Yiming; Zhang, Yalei; Zhou, Xuefei

2018-05-10

Hexavalent chromium (Cr(VI)) reduction by Geobacter sulfurreducens PCA was evaluated in batch experiments, and the form and amounts of intracellular and extra-cellular Cr(VI) reduction products were determined over time. The first-order Cr(VI) reduction rate per unit mass of cells was consistent for different initial cell concentrations, and approximately equal to (2.065 ± 0.389) x 10 -9  mL CFU -1 h -1 . A portion of the reduced Cr(VI) products precipitated on Geobacter cell walls as Cr(III) and was bound via carboxylate functional groups, a portion accumulated inside Geobacter cells, and another portion existed as soluble Cr(III) or organo-Cr(III) released to solution. A mass balance analysis of total chromium in aqueous media, on cell walls, and inside cells was determined as a function of time, and with different initial cell concentrations. Mass balances were between 92% and 98%, and indicated Cr(VI) reduction products accumulate more on cell walls and inside cells with time and with increasing initial cell concentration, as opposed to particulates in aqueous solution. Reduced Cr(VI) products both in solution and on cell surfaces appear to form organo-Cr(III) complexes, and our results suggest that such complexes are more stable to reoxidation than aqueous Cr(III) or Cr(OH) 3 . Chromium inside cells is also likely more stable to reoxidation, both because it can form organic complexes, and it is separated by the cell membrane from solution conditions. Hence, Cr(VI) reduction products in groundwater during bioremediation may become more stable against re-oxidation, and may pose a lower risk to human health, over time and with greater initial biomass densities. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hexavalent chromium removal in contaminated water using reticulated chitosan micro/nanoparticles from seafood processing wastes.

PubMed

Dima, Jimena Bernadette; Sequeiros, Cynthia; Zaritzky, Noemi E

2015-12-01

Chitosan particles (CH) were obtained from seafood processing wastes (shrimp shells) and physicochemically characterized; deacetylation degree of CH was measured by Infrared Spectroscopy (FTIR) and potentiometric titration; polymer molecular weight was determined by intrinsic viscosity measurements. Reticulated micro/nanoparticles of chitosan (MCH) with an average diameter close to 100nm were synthesized by ionic gelation of chitosan using tripolyphosphate (TPP), and characterized by SEM, size distribution and Zeta-potential. Detoxification capacities of CH and MCH were tested analyzing the removal of hexavalent chromium Cr(VI) from contaminated water, at different initial chromium concentrations. The effect of pH on adsorption capacity of CH and MCH was experimentally determined and analyzed considering the Cr(VI) stable complexes (anions) formed, the presence of protonated groups in chitosan particles and the addition of the reticulating agent (TPP). Chitosan crosslinking was necessary to adsorb Cr(VI) at pH<2 due to the instability of CH particles in acid media. Langmuir isotherm described better than Freundlich and Temkin equations the equilibrium adsorption data. Pseudo-second order rate provided the best fitting to the kinetic data in comparison to pseudo-first order and Elovich equations. Chemical analysis to determine the oxidation state of the adsorbed Cr, showed that Cr(VI) was adsorbed on CH particles without further reduction; in contrast Cr(VI) removed from the solution was reduced and bound to the MCH as Cr(III). The reduction of toxic Cr(VI) to the less or nontoxic Cr(III) by the reticulated chitosan micro/nanoparticles can be considered a very efficient detoxification technique for the treatment of Cr(VI) contaminated water. Copyright © 2015 Elsevier Ltd. All rights reserved.

FANCD2 monoubiquitination and activation by hexavalent chromium [Cr(VI)] exposure

PubMed Central

Vilcheck, Susan K.; Ceryak, Susan; O’Brien, Travis J.; Patierno, Steven R.

2007-01-01

Fanconi anemia (FA) is a rare autosomal recessive disorder characterized by congenital abnormalities, progressive bone marrow failure, and cancer susceptibility. FA cells are hypersensitive to DNA crosslinking agents. FA is a genetically heterogeneous disease with at least 11 complementation groups. The eight cloned FA proteins interact in a common pathway with established DNA-damage-response proteins, including BRCA1 and ATM. Six FA proteins (A, C, E, F, G, and L) regulate the monoubiquitination of FANCD2 after DNA damage by crosslinking agents, which targets FANCD2 to BRCA1 nuclear foci containing BRCA2 (FANCD1) and RAD51. Some forms of hexavalent chromium [Cr(VI)] are implicated as respiratory carcinogens and induce several types of DNA lesions, including DNA interstrand crosslinks. We have shown that FA-A fibroblasts are hypersensitive to both Cr(VI)-induced apoptosis and clonogenic lethality. Here we show that Cr(VI) treatment induced monoubiquitination of FANCD2 in normal human fibroblasts, providing the first molecular evidence of Cr(VI)-induced activation of the FA pathway. FA-A fibroblasts demonstrated no FANCD2 monoubiquitination, in keeping with the requirement of FA-A for this modification. We also found that Cr(VI) treatment induced significantly more S-phase-dependent DNA double strand breaks (DSBs), as measured by γ-H2AX expression, in FA-A fibroblasts compared to normal cells. However, and notably, DSBs were repaired equally in both normal and FA-A fibroblasts during recovery from Cr(VI) treatment. While previous research on FA has defined the genetic causes of this disease, it is critical in terms of individual risk assessment to address how cells from FA patients respond to genotoxic insult. PMID:16893675

Fractionation of selenium isotopes during bacterial respiratory reduction of selenium oxyanions

USGS Publications Warehouse

Herbel, M.J.; Johnson, T.M.; Oremland, R.S.; Bullen, T.D.

2000-01-01

Reduction of selenium oxyanions by microorganisms is an important process in the biogeochemical cycling of selenium. Numerous bacteria can reduce Se oxyanions, which are used as electron acceptors during the oxidation of organic matter in anoxic environments. In this study, we used a double spike (82Se and 74Se) thermal ionization mass spectrometry technique to quantify the isotopic fractionation achieved by three different species of anaerobic bacteria capable of accomplishing growth by respiratory reduction of selenate [SeO42- or Se(VI)] or selenite [SeO32- or Se(IV)] to Se(IV) or elemental selenium [Se(0)] coupled with the oxidation of lactate. Isotopic discrimination in these closed system experiments was evaluated by Rayleigh fractionation equations and numerical models. Growing cultures of Bacillus selenitireducens, a haloalkaliphile capable of growth using Se(IV) as an electron acceptor, induced a 80Se/76Se fractionation of -8.0 ?? 0.4??? (instantaneous ?? value) during reduction of Se(IV) to Se(0). With Bacillus arsenicoselenatis, a haloalkaliphile capable of growth using Se(VI) as an electron acceptor, fractionations of -5.0 ?? 0.5??? and -6.0 ?? 1.0??? were observed for reduction of Se(VI) to Se(IV) and reduction of Se(IV) to Se(0), respectively. In growing cultures of Sulfurospirillum barnesii, a freshwater species capable of growth using Se(VI), fractionation was small initially, but near the end of the log growth phase, it increased to -4.0 ?? 1.0??? and -8.4 ?? 0.4??? for reduction of Se(VI) to Se(IV) and reduction of Se(IV) to Se(O), respectively. Washed cell suspensions of S. barnesii induced fractionations of -1.1 ?? 0.4??? during Se(VI) reduction, and -9.1 ?? 0.5% for Se(IV) reduction, with some evidence for smaller values (e.g., -1.7???) in the earliest-formed Se(0) results. These results demonstrate that dissimilatory reduction of selenate or selenite induces significant isotopic fractionation, and suggest that significant Se isotope ratio variation will be found in nature. Copyright (C) 2000 Elsevier Science Ltd.

Temporal variations in dissolved selenium in Lake Kinneret (Israel)

USGS Publications Warehouse

Nishri, A.; Brenner, I.B.; Hall, G.E.M.; Taylor, Howard E.

1999-01-01

Selenium is an essential micronutrient for the growth of the dinoflagellate Peridinium gatunense that dominates the spring algal bloom in Lake Kinneret (LK). The relationship between the levels of dissolved selenium species and the occurance of algal blooms in this lake was studied. During algal blooms of P. gatunense in spring and of the blue-green Aphanizomenon ovalisporum in fall (in 1994) the concentration of epilimnetic dissolved organic Se (Se(org)) increased whereas that of selenite (SeIV) decreased, to levels below the limit of detection: 5 ng/l. The disappearance of SeIV during these blooms is attributed to algal uptake and it is suggested that the growth of both algae may have depended on Se(org) regeneration. A budget performed for selenate (SeVI) suggests that this species is also consumed by algae but to a lesser extent than SeIV (in 1994 ~40% of the epilimnetic load). During the stratification period the hypolimnion of Lake Kinneret becomes anoxic, with high levels of dissolved sulfide. The affects of this environment on the distribution of Se oxy-anions, selenite (SeIV) and selenate(SeVI), were also studied. At the onset of thermal stratification (March) about 35% of the lake inventory of both Se oxidized species are entrapped in the hypolimnion. During stages of oxygen depletion and H2S accumulation, SeIV is completely and SeVI partially removed from this layer. The removal is attributed to reduction followed by formation of particulate reduced products, such as elemental selenium Se(o). The ratio between SeVI to total dissolved selenium (SE(T)) in water sources to the lake is ~0.84, about twice the corresponding ratio in the lake (~0.44, during holomixis). In the lake about 75% of annual SeVI inflow from external sources undergoes reduction to selenide (Se-II) and Se(o) through epilimnetic algal assimilation and hypolimnetic anoxic reduction, respectively. It is suggested that the latter oxidation of the dissolved organic selenide released from biogenic particles and of Se(o) only to the tetravalent species is the cause for the lower ratio of SeVI/Se(T) in the lake.

Technique of investigations of thermomagnetic Nernst-Ettingshausen and Maggi-Righi-Leduc effects in micro-samples at ultrahigh pressure

NASA Astrophysics Data System (ADS)

Ovsyannikov, Sergey; Shchennikov, Vladimir

2004-03-01

In the present work the novel technique of investigation of thermomagnetic effects (longitudinal and transverse Nernst-Ettingshausen effects, Maggi-Righi-Leduc effects) on semiconductor micro-samples at high pressure up to 30 GPa has been developed. The technique has been applied for characterisation of semiconductor micro-samples and minerals of VI, IV-VI, and II-VI Groups. Advantages of thermomagnetic effects over the traditional galvanomagnetic ones have been demonstrated. It has been shown that technique of thermomagnetic measurements at high pressure is a powerful tool in studying of parameters of electron structure of semiconductors and being the perspective one for any technological applications. The work was supported by the Russian Foundation for Basic Research, Gr. No. 01-02-17203.

Final Technical Report -- GEO-VI - USGEO

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

Hirsch, Leonard

2009-11-30

Representatives of US earth observations departments and agencies, other participating governments, NGOs and civil society participated in the Sixth Plenary Meeting of the Group on Earth Observations (GEO-VI), hosted by the United States in Washington, DC on November 17 and 18, 2009. The meeting was held in the Atrium Ballroom of the Ronald Reagan International Trade Center. Exhibitions of international Earth observation technology and programs were held concurrently in the same venue. A number of GEO committee meetings and side events were held in conjunction with the GEO-VI Plenary, including the GEO-IGOS Symposium on Earth observation science and applications, themore » GEOSS in the Americas Forum on Coastal Zones, and separate meetings of the GEO Communities of Practice on Carbon, Health, and Air Quality.« less

Molecular-scale characterization of uranium sorption by bone apatite materials for a permeable reactive barrier demonstration

USGS Publications Warehouse

Fuller, C.C.; Bargar, J.R.; Davis, J.A.

2003-01-01

Uranium binding to bone charcoal and bone meal apatite materials was investigated using U LIII-edge EXAFS spectroscopy and synchrotron source XRD measurements of laboratory batch preparations in the absence and presence of dissolved carbonate. Pelletized bone char apatite recovered from a permeable reactive barrier (PRB) at Fry Canyon, UT, was also studied. EXAFS analyses indicate that U(VI) sorption in the absence of dissolved carbonate occurred by surface complexation of U(VI) for sorbed concentrations ??? 5500 ??g U(VI)/g for all materials with the exception of crushed bone char pellets. Either a split or a disordered equatorial oxygen shell was observed, consistent with complexation of uranyl by the apatite surface. A second shell of atoms at a distance of 2.9 A?? was required to fit the spectra of samples prepared in the presence of dissolved carbonate (4.8 mM total) and is interpreted as formation of ternary carbonate complexes with sorbed U(VI). A U-P distance at 3.5-3.6 A?? was found for most samples under conditions where uranyl phosphate phases did not form, which is consistent with monodentate coordination of uranyl by phosphate groups in the apatite surface. At sorbed concentrations ??? 5500 ??g U(VI)/g in the absence of dissolved carbonate, formation of the uranyl phosphate solid phase, chernikovite, was observed. The presence of dissolved carbonate (4.8 mM total) suppressed the formation of chernikovite, which was not detected even with sorbed U(VI) up to 12 300 ??g U(VI)/g in batch samples of bone meal, bone charcoal, and reagent-grade hydroxyapatite. EXAFS spectra of bone char samples recovered from the Fry Canyon PRB were comparable to laboratory samples in the presence of dissolved carbonate where U(VI) sorption occurred by surface complexation. Our findings demonstrate that uranium uptake by bone apatite will probably occur by surface complexation instead of precipitation of uranyl phosphate phases under the groundwater conditions found at many U-contaminated sites.

Help needed in medication self-management for people with visual impairment: case–control study

PubMed Central

McCann, Roseleen M; Jackson, A Jonathan; Stevenson, Michael; Dempster, Martin; McElnay, James C; Cupples, Margaret E

2012-01-01

Background Visual impairment (VI) is rising in prevalence and contributing to increasing morbidity, particularly among older people. Understanding patients’ problems is fundamental to achieving optimal health outcomes but little is known about how VI impacts on self-management of medication. Aim To compare issues relating to medication self-management between older people with and without VI. Design and setting Case–control study with participants aged ≥65 years, prescribed at least two long-term oral medications daily, living within the community. Method The study recruited 156 patients with VI (best corrected visual acuity [BCVA] 6/18 to 3/60) at low-vision clinics; community optometrists identified 158 controls (BCVA 6/9 or better). Researchers visited participants in their homes, administered two validated questionnaires to assess medication adherence (Morisky; Medication Adherence Report Scale [MARS]), and asked questions about medication self-management, beliefs, and support. Results Approximately half of the participants in both groups reported perfect adherence on both questionnaires (52.5% Morisky; 43.3%, MARS). Despite using optical aids, few (3%) with VI could read medication information clearly; 24% had difficulty distinguishing different tablets. More people with VI (29%) than controls (13%) (odds ratio [OR] = 2.8; 95% confidence interval [CI] = 1.6 to 5.0) needed help managing their medication, from friends (19% versus 10%) or pharmacists (10% versus 2.5%; OR = 4.4, 95% CI = 1.4 to 13.5); more received social service support (OR = 7.1; 95% CI = 3.9 to 12.9). Conclusion Compared to their peers without VI, older people with VI are more than twice as likely to need help in managing medication. In clinical practice in primary care, patients’ needs for practical support in taking prescribed treatment must be recognised. Strategies for effective medication self-management should be explored. PMID:22867676

Nonablative Fractional Laser Resurfacing for Acne Scarring in Patients With Fitzpatrick Skin Phototypes IV-VI.

PubMed

Alexis, Andrew F; Coley, Marcelyn K; Nijhawan, Rajiv I; Luke, Janiene D; Shah, Sejal K; Argobi, Yahya A; Nodzenski, Michael; Veledar, Emir; Alam, Murad

2016-03-01

There is a paucity of studies investigating laser resurfacing in Fitzpatrick skin phototypes (SPT) IV to VI. To assess the efficacy and safety of fractional nonablative laser resurfacing in the treatment of acne scarring in patients with SPT IV to VI. The authors conducted a randomized, investigator-blinded and rater-blinded, split-face comparative study of adults with SPT IV to VI and facial acne scars treated with 2 different density settings and the same fluence. Quantitative global scarring grading system (QGSGS) scores were significantly improved from baseline at 16 and 24 weeks (p = .0277). Improvements in QGSGS scores after higher and lower density treatments were statistically similar (p = .96). The live-blinded dermatologist, the blinded dermatologist photoraters, and the patients rated scars as being significantly more improved by visual analog scale at weeks 16 and 24 compared with baseline (p < .001) for both treatment densities. Five of 7 and 3 of 7 patients in the higher and lower density group, respectively, experienced mild or moderate hyperpigmentation as an investigator observed site reaction. The nonablative 1550-nm fractional laser is safe and efficacious in treating acne scaring in Fitzpatrick skin types IV to VI. Self-limited postinflammatory hyperpigmentation was a common occurrence, especially with higher treatment densities.

U.S. Army War College Key Strategic Issues List

DTIC Science & Technology

2008-07-01

post “operational or strategic event,” compare the pre-event modeled outcome to the post- event ground truth . Considering the elements of PMESII...Personnel Management, and Culture: 1. What is the future of telecommuting in the Army and its implications on performance and productivity? 2. On...requirements. VI. Underground Facilities as a National Security Challenge: 1. The construction and employment of Hard and Deeply Buried Targets (HDBTs

20 CFR 645.410 - What elements will the State use in distributing funds within the State?

Code of Federal Regulations, 2011 CFR

2011-04-01

...)(vi)(I)(aa) of the Act. The Governor is to distribute funds to a local area or SDA based on the number by which the population of the area with an income that is less than the poverty line exceeds 7.5 percent of the total population of the area, compared to all such numbers in all such areas in the State...

20 CFR 645.410 - What elements will the State use in distributing funds within the State?

Code of Federal Regulations, 2013 CFR

2013-04-01

...)(vi)(I)(aa) of the Act. The Governor is to distribute funds to a local area or SDA based on the number by which the population of the area with an income that is less than the poverty line exceeds 7.5 percent of the total population of the area, compared to all such numbers in all such areas in the State...

An upper limit on interstellar C IV in the spectrum of gamma-2 Velorum

NASA Technical Reports Server (NTRS)

Lengyel-Frey, D.; Stecher, T. P.; West, D. K.

1975-01-01

An upper limit on the column density of C IV along the line of sight to gamma-2 Vel is derived from upper limits placed on the equivalent widths of the interstellar C IV doublet with rest wavelengths at 1548.20 A and 1550.77 A. A lower limit of 250,000 K is calculated for the electron temperature of O VI emitting regions by combining the C IV results with a measurement of the column density of interstellar O VI for the same star and using calculations for the relative ionization of some abundant elements as a function of electron temperature in a low-density plasma. Since gamma-2 Vel is in the central part of the Gum Nebula, the high temperature suggested by these results is shown to support the idea that a high-temperature phase of the interstellar medium, possibly maintained by supernova explosions, may exist.-

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

NASA Astrophysics Data System (ADS)

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

2017-09-01

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

Sustaining advocacy and action on women's participation and gender equality in adult education

NASA Astrophysics Data System (ADS)

Medel-Añonuevo, Carolyn; Bernhardt, Anna

2011-08-01

This article gives an overview of the development of gender equality and women's participation in adult learning and education in the history of the International Conferences on Adult Education (CONFINTEA). Though the equality of rights was highlighted throughout the various conferences, the first Global Report on Adult Learning and Education (GRALE) observed that a gender gap in the participation in adult learning and education still persisted in 2009. This is especially remarkable with regard to the impact of CONFINTEA V in 1997, because it focused on the issue of women's participation and gender equality. A review of the CONFINTEA VI programme elements and the national reports prepared by UNESCO Member States in 2008 reveals that gender issues have to some extent moved from the centre of attention to the periphery. This article therefore tries to explore how gender principles are acknowledged in CONFINTEA VI and its follow-up.

Uranyl adsorption and surface speciation at the imogolite-water interface: Self-consistent spectroscopic and surface complexation models

USGS Publications Warehouse

Arai, Y.; McBeath, M.; Bargar, J.R.; Joye, J.; Davis, J.A.

2006-01-01

Macro- and molecular-scale knowledge of uranyl (U(VI)) partitioning reactions with soil/sediment mineral components is important in predicting U(VI) transport processes in the vadose zone and aquifers. In this study, U(VI) reactivity and surface speciation on a poorly crystalline aluminosilicate mineral, synthetic imogolite, were investigated using batch adsorption experiments, X-ray absorption spectroscopy (XAS), and surface complexation modeling. U(VI) uptake on imogolite surfaces was greatest at pH ???7-8 (I = 0.1 M NaNO3 solution, suspension density = 0.4 g/L [U(VI)]i = 0.01-30 ??M, equilibration with air). Uranyl uptake decreased with increasing sodium nitrate concentration in the range from 0.02 to 0.5 M. XAS analyses show that two U(VI) inner-sphere (bidentate mononuclear coordination on outer-wall aluminol groups) and one outer-sphere surface species are present on the imogolite surface, and the distribution of the surface species is pH dependent. At pH 8.8, bis-carbonato inner-sphere and tris-carbonato outer-sphere surface species are present. At pH 7, bis- and non-carbonato inner-sphere surface species co-exist, and the fraction of bis-carbonato species increases slightly with increasing I (0.1-0.5 M). At pH 5.3, U(VI) non-carbonato bidentate mononuclear surface species predominate (69%). A triple layer surface complexation model was developed with surface species that are consistent with the XAS analyses and macroscopic adsorption data. The proton stoichiometry of surface reactions was determined from both the pH dependence of U(VI) adsorption data in pH regions of surface species predominance and from bond-valence calculations. The bis-carbonato species required a distribution of surface charge between the surface and ?? charge planes in order to be consistent with both the spectroscopic and macroscopic adsorption data. This research indicates that U(VI)-carbonato ternary species on poorly crystalline aluminosilicate mineral surfaces may be important in controlling U(VI) mobility in low-temperature geochemical environments over a wide pH range (???5-9), even at the partial pressure of carbon dioxide of ambient air (pCO2 = 10-3.45 atm). ?? 2006 Elsevier Inc. All rights reserved.

In vivo antitumour potential of camel's milk against hepatocellular carcinoma in rats and its improvement of cisplatin renal side effects.

PubMed

El Miniawy, Hala M F; Ahmed, Kawkab A; Mansour, Sameeh A; Khattab, Marwa M Salah

2017-12-01

Camel milk (CM) is recommended for liver disease patients in Egypt for a strong belief that it has a curative effect. The effect of consumption of CM with or without chemotherapeutic drug cisplatin was evaluated on induced hepatocarcinogenesis in rats. Wistar male rats (56) were divided into eight groups (7 rats each). Group I was control. Hepatocarcinogenesis was initiated by a single dose of intraperitoneal injection of diethylnitrosamine (DENA) (200 mg/kg BW) and promoted by phenobarbitone (500 ppm) in drinking water in groups V, VI, VII and VIII. Treatment started from 28th till 38th week using CM (5 mL/day) and/or cisplatin (5 mg/kg/3 weeks) in groups II, III IV, VI, VII and VIII. Biochemical analysis, lipid peroxidation and superoxide dismutase (SOD) activity in liver tissue were performed. Histopathology of liver and kidney and immunohistochemistry of placental glutathione-S-transferase (P-GST) in liver were performed and analyzed using image analysis. Albumin concentration and SOD activity were 3.13 ± 0.23 and 311.45 ± 41.71 in group VII (DENA & cisplatin), whereas they were 4.3 ± 0.15 and 540.5 ± 29.94 in group VII (DENA, CM and cisplatin). The mean area of altered hepatocellular foci and P-GST altered foci decreased in group VI (DENA and CM) (1049.6 ± 174.78 and 829.1 ± 261) and group VIII (cisplatin and CM) (1615.12 ± 436 and 543.9 ± 127) compared to group V (DENA only) (4173.74 ± 510.7 and 3169.49 ± 538.61). Cisplatin caused chronic interstitial nephritis, which was slightly alleviated in group VIII (CM and cisplatin). CM had an antioxidant effect and together with cisplatin managed to decrease hepatocarcinogenesis.

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

PubMed

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

2009-01-01

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

Comparison of tissue viability imaging and colorimetry: skin blanching.

PubMed

Zhai, Hongbo; Chan, Heidi P; Farahmand, Sara; Nilsson, Gert E; Maibach, Howard I

2009-02-01

Operator-independent assessment of skin blanching is important in the development and evaluation of topically applied steroids. Spectroscopic instruments based on hand-held probes, however, include elements of operator dependence such as difference in applied pressure and probe misalignment, while laser Doppler-based methods are better suited for demonstration of skin vasodilatation than for vasoconstriction. To demonstrate the potential of the emerging technology of Tissue Viability Imaging (TiVi) in the objective and operator-independent assessment of skin blanching. The WheelsBridge TiVi600 Tissue Viability Imager was used for quantification of human skin blanching with the Minolta chromameter CR 200 as an independent colorimeter reference method. Desoximetasone gel 0.05% was applied topically on the volar side of the forearm under occlusion for 6 h in four healthy adults. In a separate study, the induction of blanching in the occlusion phase was mapped using a transparent occlusion cover. The relative uncertainty in the blanching estimate produced by the Tissue Viability Imager was about 5% and similar to that of the chromameter operated by a single user and taking the a(*) parameter as a measure of blanching. Estimation of skin blanching could also be performed in the presence of a transient paradoxical erythema, using the integrated TiVi software. The successive induction of skin blanching during the occlusion phase could readily be mapped by the Tissue Viability Imager. TiVi seems to be suitable for operator-independent and remote mapping of human skin blanching, eliminating the main disadvantages of methods based on hand-held probes.

Effectiveness and sustainability of the ViSC Social Competence Program to prevent cyberbullying and cyber-victimization: Class and individual level moderators.

PubMed

Gradinger, Petra; Yanagida, Takuya; Strohmeier, Dagmar; Spiel, Christiane

2016-01-01

We investigated whether the general anti-bullying program ViSC sustainably prevents cyberbullying and cyber-victimization. A longitudinal randomized control group design was used to examine (i) program effectiveness immediately after a 1 year implementation phase and (ii) sustainable program effects 6 months later taking several moderators on the class level (class climate and ethnic diversity) and on the individual level (gender, age, internet usage, traditional bullying/victimization) into account. Effectiveness (e.g., the change between waves 2 and 1) was examined in 2,042 students (47.6% girls), aged 11.7 years (SD = 0.88) enrolled in 18 schools and 103 classes. Sustainability (e.g., the change between waves 3 and 2) was examined in a sub-sample of 6 schools and 35 classes comprising 659 students. The self-assessment multiple-item scales showed longitudinal and multiple group invariance. Factor scores were extracted to compute difference scores for effectiveness (Posttest minus Pretest) and sustainability (Follow-up test minus Posttest) for cyberbullying and cyber-victimization. Multilevel Modeling was applied to examine (i) the effectiveness and (ii) the sustainability of the ViSC intervention controlling for several individual and class level variables. Controlling for covariates, it was demonstrated that the ViSC program is effective in preventing cyberbullying and cyber-victimization and that the effects are sustainable after 6 months. The consequences for cyberbullying prevention are discussed. © 2016 Wiley Periodicals, Inc.

76 FR 67759 - Notice on Outer Continental Shelf Oil and Gas Lease Sales

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-02

... and Exploration Company Inexeco Oil Company Group VI Eni Petroleum Co. Inc. Eni Petroleum US LLC Eni Oil US LLC Eni Marketing Inc Eni BB Petroleum Inc. Eni US Operating Co. Inc. Eni BB Pipeline LLC Group...

76 FR 28449 - Notice on Outer Continental Shelf Oil and Gas Lease Sales

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-17

... Company, Inexeco Oil Company. Group VI. Eni Petroleum Co. Inc., Eni Petroleum US LLC, Eni Oil US LLC, Eni Marketing Inc., Eni BB Petroleum Inc., Eni US Operating Co. Inc., Eni BB Pipeline LLC. Group VII. Petrobras...

Benefits of High-dose Steroid + Hespander + Mannitol Administration in the Treatment of Bell's Palsy.

PubMed

Furukawa, Takatoshi; Abe, Yasuhiro; Ito, Tsukasa; Kubota, Toshinori; Kakehata, Seiji

2017-02-01

Large-scale investigations have not been recently conducted on the efficacy of high-dose steroid administration of prednisolone (PSL) for Bell's palsy. We compared treatment results between normal-dose steroid (PSL 60 mg/d) and high-dose steroid (PSL 200 mg/d) + Hespander + Mannitol administration. We also investigated the recovery rate for antiviral agents. Retrospective case review. Tertiary referral center. A total of 675 patients with Bell's palsy who had grade V and grade VI on the House-Brackmann (HB) scale were treated in our department between 1995 and 2014. These patients could be divided into a normal-dose group and high-dose group. We separately assessed treatment outcomes for HB grade V patients and HB grade VI patients. Logistic regression analysis was also performed to investigate factors that can impact treatment outcomes, i.e., sex, age, days to start of treatment, PSL dosage, and antiviral drug administration. Recovery rates were significantly better in the high-dose steroid + Hespander + Mannitol group in comparison with the normal-dose steroid group for HB grade V (100% versus 77.7%) and HB grade VI (92.5% versus 68.2%). Additional effects of antiviral agents were only shown in the normal-dose group. Significant factors for treatment outcomes were PSL 200 mg/d administration and early initiation of treatment. Insignificant factors were sex, age, and the antiviral agent. We showed the high-dose steroid + Hespander + Mannitol administration produced significantly better outcomes than normal-dose steroid administration in the treatment of patients with Bell's palsy.

40 CFR 63.1510 - Monitoring requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... pollution control device. (c) Labeling. The owner or operator must inspect the labels for each group 1... of a group 1 furnace (with or without add-on air pollution control devices) or in-line fluxer. The... the information in § 63.1516(b)(2)(vi). (n) Sidewell group 1 furnace with add-on air pollution control...

40 CFR 63.1510 - Monitoring requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... of a group 1 furnace (with or without add-on air pollution control devices) or in-line fluxer. The... the information in § 63.1516(b)(2)(vi). (n) Sidewell group 1 furnace with add-on air pollution control...). (o) Group 1 furnace without add-on air pollution control devices. These requirements apply to the...

40 CFR 63.1510 - Monitoring requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... pollution control device. (c) Labeling. The owner or operator must inspect the labels for each group 1... of a group 1 furnace (with or without add-on air pollution control devices) or in-line fluxer. The... the information in § 63.1516(b)(2)(vi). (n) Sidewell group 1 furnace with add-on air pollution control...

40 CFR 63.1510 - Monitoring requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... of a group 1 furnace (with or without add-on air pollution control devices) or in-line fluxer. The... the information in § 63.1516(b)(2)(vi). (n) Sidewell group 1 furnace with add-on air pollution control...). (o) Group 1 furnace without add-on air pollution control devices. These requirements apply to the...

34 CFR 491.21 - What selection criteria does the Secretary use?

Code of Federal Regulations, 2010 CFR

2010-07-01

... and group mental health counseling; (iv) Health care; (v) Child care; (vi) Case management; (vii) Job... support services to address the most pressing needs of the target group at, or through, the project site. Support services must be designed to bring members of the target group to a state of readiness for...

40 CFR 63.1510 - Monitoring requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... of a group 1 furnace (with or without add-on air pollution control devices) or in-line fluxer. The... the information in § 63.1516(b)(2)(vi). (n) Sidewell group 1 furnace with add-on air pollution control...). (o) Group 1 furnace without add-on air pollution control devices. These requirements apply to the...

Biogenic non-crystalline U(IV) revealed as major component in uranium ore deposits

NASA Astrophysics Data System (ADS)

Bhattacharyya, Amrita; Campbell, Kate M.; Kelly, Shelly D.; Roebbert, Yvonne; Weyer, Stefan; Bernier-Latmani, Rizlan; Borch, Thomas

2017-06-01

Historically, it is believed that crystalline uraninite, produced via the abiotic reduction of hexavalent uranium (U(VI)) is the dominant reduced U species formed in low-temperature uranium roll-front ore deposits. Here we show that non-crystalline U(IV) generated through biologically mediated U(VI) reduction is the predominant U(IV) species in an undisturbed U roll-front ore deposit in Wyoming, USA. Characterization of U species revealed that the majority (~58-89%) of U is bound as U(IV) to C-containing organic functional groups or inorganic carbonate, while uraninite and U(VI) represent only minor components. The uranium deposit exhibited mostly 238U-enriched isotope signatures, consistent with largely biotic reduction of U(VI) to U(IV). This finding implies that biogenic processes are more important to uranium ore genesis than previously understood. The predominance of a relatively labile form of U(IV) also provides an opportunity for a more economical and environmentally benign mining process, as well as the design of more effective post-mining restoration strategies and human health-risk assessment.

Characterization of a new ViI-like Erwinia amylovora bacteriophage phiEa2809.

PubMed

Lagonenko, Alexander L; Sadovskaya, Olga; Valentovich, Leonid N; Evtushenkov, Anatoly N

2015-04-01

Erwinia amylovora is a Gram-negative plant pathogenic bacteria causing fire blight disease in many Rosaceae species. A novel E. amylovora bacteriophage, phiEa2809, was isolated from symptomless apple leaf sample collected in Belarus. This phage was also able to infect Pantoea agglomerans strains. The genome of phiEa2809 is a double-stranded linear DNA 162,160 bp in length, including 145 ORFs and one tRNA gene. The phiEa2809 genomic sequence is similar to the genomes of the Serratia plymutica phage MAM1, Shigella phage AG-3, Dickeya phage vB DsoM LIMEstone1 and Salmonella phage ViI and lacks similarity to described E. amylovora phage genomes. Based on virion morphology (an icosahedral head, long contractile tail) and genome structure, phiEa2809 was classified as a member of Myoviridae, ViI-like bacteriophages group. PhiEa2809 is the firstly characterized ViI-like bacteriophage able to lyse E. amylovora. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Biogenic non-crystalline U(IV) revealed as major component in uranium ore deposits

PubMed Central

Bhattacharyya, Amrita; Campbell, Kate M.; Kelly, Shelly D.; Roebbert, Yvonne; Weyer, Stefan; Bernier-Latmani, Rizlan; Borch, Thomas

2017-01-01

Historically, it is believed that crystalline uraninite, produced via the abiotic reduction of hexavalent uranium (U(VI)) is the dominant reduced U species formed in low-temperature uranium roll-front ore deposits. Here we show that non-crystalline U(IV) generated through biologically mediated U(VI) reduction is the predominant U(IV) species in an undisturbed U roll-front ore deposit in Wyoming, USA. Characterization of U species revealed that the majority (∼58-89%) of U is bound as U(IV) to C-containing organic functional groups or inorganic carbonate, while uraninite and U(VI) represent only minor components. The uranium deposit exhibited mostly 238U-enriched isotope signatures, consistent with largely biotic reduction of U(VI) to U(IV). This finding implies that biogenic processes are more important to uranium ore genesis than previously understood. The predominance of a relatively labile form of U(IV) also provides an opportunity for a more economical and environmentally benign mining process, as well as the design of more effective post-mining restoration strategies and human health-risk assessment. PMID:28569759

Biogenic non-crystalline U (IV) revealed as major component in uranium ore deposits

DOE PAGES

Bhattacharyya, Amrita; Campbell, Kate M.; Kelly, Shelly D.; ...

2017-06-01

Historically, it is believed that crystalline uraninite, produced via the abiotic reduction of hexavalent uranium (U (VI)) is the dominant reduced U species formed in low-temperature uranium roll-front ore deposits. Here we show that non-crystalline U (IV) generated through biologically mediated U (VI) reduction is the predominant U (IV) species in an undisturbed U roll-front ore deposit in Wyoming, USA. Characterization of U species revealed that the majority (~58-89%) of U is bound as U (IV) to C-containing organic functional groups or inorganic carbonate, while uraninite and U (VI) represent only minor components. The uranium deposit exhibited mostly 238U-enriched isotopemore » signatures, consistent with largely biotic reduction of U (VI) to U (IV). This finding implies that biogenic processes are more important to uranium ore genesis than previously understood. The predominance of a relatively labile form of U (IV) also provides an opportunity for a more economical and environmentally benign mining process, as well as the design of more effective post-mining restoration strategies and human health-risk assessment.« less

Biogenic non-crystalline U(IV) revealed as major component in uranium ore deposits.

PubMed

Bhattacharyya, Amrita; Campbell, Kate M; Kelly, Shelly D; Roebbert, Yvonne; Weyer, Stefan; Bernier-Latmani, Rizlan; Borch, Thomas

2017-06-01

Historically, it is believed that crystalline uraninite, produced via the abiotic reduction of hexavalent uranium (U (VI) ) is the dominant reduced U species formed in low-temperature uranium roll-front ore deposits. Here we show that non-crystalline U (IV)  generated through biologically mediated U (VI)  reduction is the predominant U (IV)  species in an undisturbed U roll-front ore deposit in Wyoming, USA. Characterization of U species revealed that the majority (∼58-89%) of U is bound as U (IV) to C-containing organic functional groups or inorganic carbonate, while uraninite and U (VI) represent only minor components. The uranium deposit exhibited mostly 238 U-enriched isotope signatures, consistent with largely biotic reduction of U (VI) to U (IV) . This finding implies that biogenic processes are more important to uranium ore genesis than previously understood. The predominance of a relatively labile form of U (IV) also provides an opportunity for a more economical and environmentally benign mining process, as well as the design of more effective post-mining restoration strategies and human health-risk assessment.

Biogenic non-crystalline U (IV) revealed as major component in uranium ore deposits

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

Bhattacharyya, Amrita; Campbell, Kate M.; Kelly, Shelly D.

Historically, it is believed that crystalline uraninite, produced via the abiotic reduction of hexavalent uranium (U (VI)) is the dominant reduced U species formed in low-temperature uranium roll-front ore deposits. Here we show that non-crystalline U (IV) generated through biologically mediated U (VI) reduction is the predominant U (IV) species in an undisturbed U roll-front ore deposit in Wyoming, USA. Characterization of U species revealed that the majority (~58-89%) of U is bound as U (IV) to C-containing organic functional groups or inorganic carbonate, while uraninite and U (VI) represent only minor components. The uranium deposit exhibited mostly 238U-enriched isotopemore » signatures, consistent with largely biotic reduction of U (VI) to U (IV). This finding implies that biogenic processes are more important to uranium ore genesis than previously understood. The predominance of a relatively labile form of U (IV) also provides an opportunity for a more economical and environmentally benign mining process, as well as the design of more effective post-mining restoration strategies and human health-risk assessment.« less

Biogenic non-crystalline U(IV) revealed as major component in uranium ore deposits

USGS Publications Warehouse

Bhattacharyya, Amrita; Campbell, Kate M.; Kelly, Shelly; Roebbert, Yvonne; Weyer, Stefan; Bernier-Latmani, Rizlan; Borch, Thomas

2017-01-01

Historically, it is believed that crystalline uraninite, produced via the abiotic reduction of hexavalent uranium (U(VI)) is the dominant reduced U species formed in low-temperature uranium roll-front ore deposits. Here we show that non-crystalline U(IV) generated through biologically mediated U(VI) reduction is the predominant U(IV) species in an undisturbed U roll-front ore deposit in Wyoming, USA. Characterization of U species revealed that the majority (∼58-89%) of U is bound as U(IV)to C-containing organic functional groups or inorganic carbonate, while uraninite and U(VI) represent only minor components. The uranium deposit exhibited mostly 238U-enriched isotope signatures, consistent with largely biotic reduction of U(VI) to U(IV). This finding implies that biogenic processes are more important to uranium ore genesis than previously understood. The predominance of a relatively labile form of U(IV) also provides an opportunity for a more economical and environmentally benign mining process, as well as the design of more effective post-mining restoration strategies and human health-risk assessment.

Energy reserve modification in different age groups of Daphnia schoedleri (Anomopoda: Daphniidae) exposed to hexavalent chromium.

PubMed

Arzate-Cárdenas, Mario Alberto; Martínez-Jerónimo, Fernando

2012-07-01

Caloric content is a reliable biomaker of effect since it is modified by exposure to toxicants that can alter basal metabolism. Since organisms' age modifies how energy resources are allocated and modifies the activity of antioxidant enzymes, the response to toxic agents could be altered with age. Seven age groups of Daphnia schoedleri (0, 3, 5, 7, 14, 21, and 28-day-old) were exposed for 24h to two sublethal concentrations of Cr(VI): 1/25 and 1/5 of the 48 h EC(50) of each age group, to determine the age at which susceptibility to Cr(VI) is highest. To evaluate energy content, carbohydrate, protein and lipid reserves were quantified and antioxidant enzymes activity was assessed (SOD, CAT, GPx, and GR). Furthermore, an integrative approach was applied to evaluate both sets of responses and interpret them as a whole in a simply visual way, achieved by the integrated biomarker response approach. Results indicate that Cr(VI) induced significant differences in all age groups. Seven and 14-day-old organisms were exposed to the highest concentrations (based on their EC50) and showed greater tolerance to this metal. Susceptibility to the toxicant was highest in younger specimens in which energy requirements are greater due to high growth rates (basal metabolism), as a result of which more energy reserves are expended to satisfy demands in terms of growth and response to toxicants. Copyright © 2012 Elsevier B.V. All rights reserved.

Assessing natural attenuation potential at a uranium (U) in situ recovery site (Rosita, TX, USA) using multiple redox-sensitive isotope systems

NASA Astrophysics Data System (ADS)

Basu, A.; Brown, S. T.; Christensen, J. N.; DePaolo, D. J.; Reimus, P. W.; Heikoop, J. M.; Simmons, A. M.; House, B.; Schilling, K.; Johnson, T. M.; Pelizza, M.

2013-12-01

The In Situ Recovery (ISR) U mining operation at Rosita, TX, USA, involved oxidative dissolution of U from roll front U deposits. This process mobilized U along with other characteristic elements (e.g., Se) from the roll fronts in their soluble and toxic oxidized forms (e.g., U(VI), Se(VI)). The dissolved U(VI) in groundwater poses significant ecological risk due to its chemical toxicity and must be restored below the existing regulatory limit to minimize the environmental impact of ISR mining. However, the undisturbed sediments downgradient to the roll front deposits are expected to remain reduced. Naturally occurring Fe-minerals (e.g., FeS, siderite, magnetite) and microorganisms in the sediments downgradient to ISR activity can reduce dissolved U(VI) to less toxic and insoluble U(IV) and promote natural attenuation. The reduction of oxyanions of U or Se induces measurable isotopic fractionation that can be used to monitor the natural attenuation by downgradient sediments. Here, we used multiple redox-sensitive isotope systems (U, Se, and S) to detect reducing conditions and natural attenuation of U(VI) at the ISR site. We collected groundwater samples from 26 wells located in the ore body, upgradient and downgradient to the ore body. The δ238U values measured in groundwater samples from 23 wells range from 0.48‰ to -1.66‰ (×0.12‰). A preliminary investigation of 6 groundwater samples shows a variation of δ82Se values from -1.44‰ to 5.24‰ (×0.15‰). The δ34SO4 measurements in groundwater vary from 11.8‰ to -19.9‰. The reduction of Se(VI) and SO42- fractionates the lighter isotopes (i.e., 32S and 76Se) in the reduced product phase rendering the remaining reactants in the groundwater enriched in heavier isotopes. Therefore, the high δ82Se and δ34SO4 values may suggest reduction of Se(VI) and SO42-, respectively. The highest δ238U values are observed in the wells located in the ore body or upgradient to the ore body whereas the downgradient wells show significantly lower δ238U values. High δ238U values in most of the wells located in the ore-zone may be attributed to the dissolution of the U ore enriched in 238U. The low δ238U values are generally observed in the wells with low U(VI) concentrations. Since U(VI) reduction fractionates 238U to the solid U(IV) phase, the depletion of 238U in the groundwater samples in the downgradient monitoring wells suggest U(VI) reduction by the downgradient sediments. The δ238U values in the groundwater samples conform to a Rayleigh distillation model with an isotopic fractionation factor α = 1.00013 × 0.00010. Future investigations include characterization of the U ore bearing sediments collected from boreholes in the ore body and downgradient of the ore body, measurement of the δ238U and δ82Se values in the ore and in remaining groundwater samples. The U(VI) reducing capacity and concomitant U isotopic fractionation factors for the sediments from downgradient boreholes will be determined from the batch incubation experiments and flow through column experiments.

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

NASA Astrophysics Data System (ADS)

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 <1 per mil. At the remaining two sites (Letnany and Velesin), the Cr isotope signature of the source of contamination was not known. At all four sites, most del53/52Cr values were positive, with means higer than 1 per mil: At Zlate Hory, del53/52Cr ranged between -2.2 and +3.0 per mil (mean of +1.5 per mil); at Loucna, del53/52Cr ranged between 0 and +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 liquid form. If, indeed, most solid Cr now present in the saturated zone had undergone anaerobic reduction, we would expect much higher del53/52Cr values of the residual liquid Cr(VI) than those actually observed. Our understanding of the system is incomplete. Currently, del53/52Cr values of the contaminated soils are being determined in an attempt to close a Cr isotope mass balance.

Far Ultraviolet Spectroscopy of the Intergalactic and Interstellar Absorption Toward 3C 273

NASA Technical Reports Server (NTRS)

Sembach, Kenneth R.; Howk, J. Christopher; Savage, Blair D.; Shull, J. Michael; Oegerle, William R.; Fisher, Richard R. (Technical Monitor)

2001-01-01

We present Far Ultraviolet Spectroscopic Explorer observations of the molecular, neutral atomic, weakly ionized, and highly ionized components of the interstellar and intergalactic material toward the quasar 3C273. We identify Ly-beta absorption in eight of the known intergalactic Ly-alpha absorbers along the sight line with the rest-frame equivalent widths W(sub r)(Ly-alpha) > 50 micro-angstroms. Refined estimates of the H(I) column densities and Doppler parameters (b) of the clouds are presented. We find a range of b = 16-46 km/s. We detect multiple H(I) lines (Ly-beta - Ly-theta) in the 1590 km/s Virgo absorber and estimate logN(H(I)) = 15.85 +/- 0.10, ten times more H(I) than all of the other absorbers along the sight line combined. The Doppler width of this absorber, b = 16 km/s, implies T < 15,000 K. We detect O(VI) absorption at 1015 km/s at the 2-3(sigma) level that may be associated with hot, X-ray emitting gas in the Virgo Cluster. We detect weak C(III) and O(VI) absorption in the IGM at z=0.12007; this absorber is predominantly ionized and has N(H+)/N(H(I)) > 4000/Z, where Z is the metallicity. Strong Galactic interstellar O(VI) is present between -100 and +100 km/s with an additional high-velocity wing containing about 13% of the total O(VI) between +100 and +240 km/s. The Galactic O(VI), N(V), and C(IV) lines have similar shapes, with roughly constant ratios across the -100 to +100 km/s velocity range. The high velocity O(VI) wing is not detected in other species. Much of the interstellar high ion absorption probably occurs within a highly fragmented medium within the Loop IV remnant or in the outer cavity walls of the remnant. Multiple hot gas production mechanisms are required. The broad O(VI) absorption wing likely traces the expulsion of hot gas out of the Galactic disk into the halo. A flux limit of 5.4 x 10(epx -16) erg/sq cm/s on the amount of diffuse O(VI) emission present = 3.5' off the 3C273 sight line combined with the observed O(VI) column density toward 3C273, logN O(VI) = 14.73 +/- 0.04, implies n(sub e) < 0.02/cubic cm and P/k < 11,500/cubic cm for an assumed temperature of 3 x 10(exp 5) K. The elemental abundances in the neutral and weakly-ionized interstellar clouds are similar to those found for other halo clouds. The warm neutral and warm ionized clouds along the sight line have similar dust-phase abundances, implying that the properties of the dust grains in the two types of clouds are similar. Interstellar H2 absorption is present at positive velocities at a level of logN(H2) = 15.71, but is very weak at the velocities of the main column density concentration along the sight line observed in H(I) 21 cm emission.

Stellar laboratories: new Ge V and Ge VI oscillator strengths and their validation in the hot white dwarf RE 0503-289

NASA Astrophysics Data System (ADS)

Rauch, T.; Werner, K.; Biémont, É.; Quinet, P.; Kruk, J. W.

2012-10-01

Context. State-of-the-art spectral analysis of hot stars by means of non-LTE model-atmosphere techniques has arrived at a high level of sophistication. The analysis of high-resolution and high-S/N spectra, however, is strongly restricted by the lack of reliable atomic data for highly ionized species from intermediate-mass metals to trans-iron elements. Especially data for the latter has only been sparsely calculated. Many of their lines are identified in spectra of extremely hot, hydrogen-deficient post-AGB stars. A reliable determination of their abundances establishes crucial constraints for AGB nucleosynthesis simulations and, thus, for stellar evolutionary theory. Aims: In a previous analysis of the UV spectrum of RE 0503-289, spectral lines of highly ionized Ga, Ge, As, Se, Kr, Mo, Sn, Te, I, and Xe were identified. Individual abundance determinations are hampered by the lack of reliable oscillator strengths. Most of these identified lines stem from Ge V. In addition, we identified Ge VI lines for the first time. We calculated Ge V and Ge VI oscillator strengths in order to reproduce the observed spectrum. Methods: We newly calculated Ge V and Ge VI oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our non-LTE stellar-atmosphere models for the analysis of the Ge iv-vi spectrum exhibited in high-resolution and high-S/N FUV (FUSE) and UV (ORFEUS/BEFS, IUE) observations of RE 0503-289. Results: In the UV spectrum of RE 0503-289, we identify four Ge IV, 37 Ge V, and seven Ge VI lines. Most of these lines are identified for the first time in any star. We can reproduce almost all Ge IV, Ge V, and Ge VI lines in the observed spectrum of RE 0503-289 (Teff = 70 kK, log g = 7.5) at log Ge = -3.8 ± 0.3 (mass fraction, about 650 times solar). The Ge iv/v/vi ionization equilibrium, that is a very sensitive Teff indicator, is reproduced well. Conclusions: Reliable measurements and calculations of atomic data are a prerequisite for stellar-atmosphere modeling. Our oscillator-strength calculations have allowed, for the first time, Ge V and Ge VI lines to be successfully reproduced in a white dwarf's (RE 0503-289) spectrum and to determine its photospheric Ge abundance. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer.Figures 4-6 and Tables 1, 3 are available in electronic form at http://www.aanda.orgTables 2 and 4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/546/A55

Mechanism of Uranium Reduction and Immobilization in Desulfovibrio vulgaris Biofilms.

PubMed

Stylo, Malgorzata; Neubert, Nadja; Roebbert, Yvonne; Weyer, Stefan; Bernier-Latmani, Rizlan

2015-09-01

The prevalent formation of noncrystalline U(IV) species in the subsurface and their enhanced susceptibility to reoxidation and remobilization, as compared to crystalline uraninite, raise concerns about the long-term sustainability of the bioremediation of U-contaminated sites. The main goal of this study was to resolve the remaining uncertainty concerning the formation mechanism of noncrystalline U(IV) in the environment. Controlled laboratory biofilm systems (biotic, abiotic, and mixed biotic-abiotic) were probed using a combination of U isotope fractionation and X-ray absorption spectroscopy (XAS). Regardless of the mechanism of U reduction, the presence of a biofilm resulted in the formation of noncrystalline U(IV). Our results also show that biotic U reduction is the most effective way to immobilize and reduce U. However, the mixed biotic-abiotic system resembled more closely an abiotic system: (i) the U(IV) solid phase lacked a typically biotic isotope signature and (ii) elemental sulfur was detected, which indicates the oxidation of sulfide coupled to U(VI) reduction. The predominance of abiotic U reduction in our systems is due to the lack of available aqueous U(VI) species for direct enzymatic reduction. In contrast, in cases where bicarbonate is present at a higher concentration, aqueous U(VI) species dominate, allowing biotic U reduction to outcompete the abiotic processes.

Data summary report for fission product release Test VI-7

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

Osborne, M.F.; Lorentz, R.A.; Travis, J.R.

Test VI-7 was the final test in the VI series conducted in the vertical furnace. The fuel specimen was a 15.2-cm-long section of a fuel rod from the Monticello boiling water reactor (BWR). The fuel had experienced a burnup of {approximately}-40 Mwd/kg U. It was heated in an induction furnace for successive 20-min periods at 2000 and 2300 K in a moist air-helium atmosphere. Integral releases were 69% for {sup 85}Kr, 52% for {sup 125}Sb, 71% for both {sup 134}Cs and {sup 137}Cs, and 0.04% for {sup 154}Eu. For the non-gamma-emitting species, release values for 42% for I, 4.1% formore » Ba, 5.3% for Mo, and 1.2% for Sr were determined. The total mass released from the furnace to the collection system, including fission products, fuel, and structural materials, was 0.89 g, with 37% being collected on the thermal gradient tubes and 63% downstream on filters. Posttest examination of the fuel specimen indicated that most of the cladding was completely oxidized to ZrO{sub 2}, but that oxidation was not quite complete at the upper end. The release behaviors for the most volatile elements, Kr and Cs, were in good agreement with the ORNL-Booth Model.« less

Oil spill vulnerability assessment integrating physical, biological and socio-economical aspects: application to the Cantabrian coast (Bay of Biscay, Spain).

PubMed

Castanedo, S; Juanes, J A; Medina, R; Puente, A; Fernandez, F; Olabarrieta, M; Pombo, C

2009-10-01

A methodology has been developed to carry out an integrated oil spill vulnerability index, V, for coastal environments. This index takes into account the main physical, biological and socio-economical characteristics by means of three intermediate indexes. Three different integration methods (worst-case, average and survey-based) along with ESI-based vulnerability scores, V(ESI), proposed for the Cantabrian coast during the Prestige oil spill, have been analyzed and compared in terms of agreement between the classifications obtained with each one for this coastal area. Results of this study indicate that the use of the worst-case index, V(R), leads to a conservative ranking, with a very poor discrimination which is not helpful in coastal oil spill risk management. Due to the homogeneity of this coastal stretch, the rest of the methods, V(I), V(M) and V(ESI), provide similar classifications. However, V(M) and V(I) give more flexibility allowing three indexes for each coastal segment and including socio-economic aspects. Finally, the V(I) procedure is proposed here as the more advisable as using this index promotes the public participation that is a key element in the implementation of Integrated Coastal Zone Management (IZCM).

Rosa damascena Mill. Essential Oil Has Protective Effect Against Testicular Damage in Diabetic Rats.

PubMed

Hamedi, Somayeh; Shomali, Tahoora; Haghighat, Aliakbar

2018-05-04

This study investigates the protective effect of Rosa damascena essential oil on diabetes-induced testicular damage in rats. Thirty-six male Wistar rats were randomly divided into 6 equal groups: Group I: negative control (no treatment); Group II: positive control (diabetic by alloxan injection); Groups III-VI that rendered diabetic and received, respectively, 50, 100, 200, and 400 µg/kg/day rose oil, orally for 28 days. Rose oil did not significantly change body weight and blood glucose level as compared to positive control. Serum testosterone level of rose oil-treated rats remained statistically the same with both negative and positive control groups (Groups I and II). Rats treated with rose oil especially at 2 higher dosages (Groups V and VI) had higher sperm count and increased diameters of seminiferous tubules as compared to Group II. Rose oil even at the lowest dosage significantly increased cell count of spermatogonia, primary spermatocytes, Sertoli cells, and Leydig cells, with better outcomes for higher dosages. It appears that short-term repeated dose administration of rose oil can dose-dependently improve structural deteriorations of testes and epididymal sperm count in diabetic rats.

77 FR 39247 - National Infrastructure Advisory Council

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-02

... opportunity to provide oral comments after the presentation of the report from the Regional Resilience Working... Resilience Working Group documenting their work to date on the Regional Resilience Study, which will be..., 2012, Minutes V. NIAC Presentation on Regional Resilience Working Group VI. Public Comment: Discussion...

Catalysts for coal liquefaction processes

DOEpatents

Garg, Diwakar

1986-01-01

Improved catalysts for catalytic solvent refining or hydroliquefaction of non-anthracitic coal at elevated temperatures under hydrogen pressure in a hydrogen donor solvent comprise a combination of zinc or copper, or a compound thereof, and a Group VI or non-ferrous Group VIII metal, or a compound thereof.

Catalysts for coal liquefaction processes

DOEpatents

Garg, D.

1986-10-14

Improved catalysts for catalytic solvent refining or hydroliquefaction of non-anthracitic coal at elevated temperatures under hydrogen pressure in a hydrogen donor solvent comprise a combination of zinc or copper, or a compound thereof, and a Group VI or non-ferrous Group VIII metal, or a compound thereof.

Integrated Multi-Color Light Emitting Device Made with Hybrid Crystal Structure

NASA Technical Reports Server (NTRS)

Park, Yeonjoon (Inventor); Choi, Sang Hyouk (Inventor)

2017-01-01

An integrated hybrid crystal Light Emitting Diode ("LED") display device that may emit red, green, and blue colors on a single wafer. The various embodiments may provide double-sided hetero crystal growth with hexagonal wurtzite III-Nitride compound semiconductor on one side of (0001) c-plane sapphire media and cubic zinc-blended III-V or II-VI compound semiconductor on the opposite side of c-plane sapphire media. The c-plane sapphire media may be a bulk single crystalline c-plane sapphire wafer, a thin free standing c-plane sapphire layer, or crack-and-bonded c-plane sapphire layer on any substrate. The bandgap energies and lattice constants of the compound semiconductor alloys may be changed by mixing different amounts of ingredients of the same group into the compound semiconductor. The bandgap energy and lattice constant may be engineered by changing the alloy composition within the cubic group IV, group III-V, and group II-VI semiconductors and within the hexagonal III-Nitrides.

Integrated Multi-Color Light Emitting Device Made with Hybrid Crystal Structure

NASA Technical Reports Server (NTRS)

Park, Yeonjoon (Inventor); Choi, Sang Hyouk (Inventor)

2016-01-01

An integrated hybrid crystal Light Emitting Diode ("LED") display device that may emit red, green, and blue colors on a single wafer. The various embodiments may provide double-sided hetero crystal growth with hexagonal wurtzite III-Nitride compound semiconductor on one side of (0001) c-plane sapphire media and cubic zinc-blended III-V or II-VI compound semiconductor on the opposite side of c-plane sapphire media. The c-plane sapphire media may be a bulk single crystalline c-plane sapphire wafer, a thin free standing c-plane sapphire layer, or crack-and-bonded c-plane sapphire layer on any substrate. The bandgap energies and lattice constants of the compound semiconductor alloys may be changed by mixing different amounts of ingredients of the same group into the compound semiconductor. The bandgap energy and lattice constant may be engineered by changing the alloy composition within the cubic group IV, group III-V, and group II-VI semiconductors and within the hexagonal III-Nitrides.

Assessment of calcium addition on the removal of U(VI) in the alkaline conditions created by NH 3 gas

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

Katsenovich, Yelena; Cardona, Claudia; Szecsody, Jim

Remediation of uranium (U) contamination in the deep vadose zone (VZ) sediments abundant in calcite mineral is a challenging task considering the formation of highly stable and mobile uranyl complexes with carbonate and calcium in pore water composition. There is a concern that uranium contamination in the VZ can serve as a continued source for groundwater pollution, creating a risk to human health and the environment through the groundwater pathway. This requires in-situ remediation of the radionuclide-contaminated VZ to convert soluble U species to low solubility precipitates that are stable in the natural environment. Injection of reactive gasses (e.g., NHmore » 3) is a promising technology to decrease U mobility in the unsaturated zone without the addition of liquid amendments. The NH 3 injection creates alkaline conditions that can alter the sediment pore water composition due to a release of elements from minerals (via desorption and dissolution) that are present in the sediment. However, it is not known how VZ pore water constituents (Si, Al 3+, HCO 3 -, and Ca 2 +) would affect U(VI) removal/precipitation in alkaline conditions. This study quantified the role of major pore water constituents typically present in the arid and semi-arid environments of the western regions of the U.S and identified solid uranium-bearing phases that could potentially precipitate from solutions approximating pore water compositions after pH manipulations via ammonia gas injections. Triplicate samples were prepared using six Si (5, 50 100, 150, 200, and 250 mM), six HCO 3 - (0, 3, 25, 50, 75, and 100 mM), and two Ca 2+ (5 and 10 mM) concentrations. The concentration of aluminum and uranium was kept constant at 5 mM and 0.0084 mM, respectively, in all synthetic formulations tested. Results showed that the percentage of U(VI) removal was controlled by the Si/Al molar ratios and Ca 2+ concentrations. Regardless of the bicarbonate concentration tested, the percentage of U(VI) removed increased as the Si/Al ratios were increased. However, higher Ca concentrations correlated with higher U(VI) removal, ranging between 96% and 99%, at low Si/Al ratios. The SEM images of dried precipitates displayed dense amorphous regions high in silica content, where EDS elemental analysis unveiled higher U atomic percentages. The formation of uranyl silicate and carbonate minerals was also predicted by the speciation modeling. XRD analysis revealed the presence of uranyl carbonate mineral phases (andersonite, grimselite); however, uranyl silicates predicted (Na-boltwoodite) were not identified experimentally, possibly due to the amorphous nature of the silica solid phases observed in our experiments.« less

A study on the dissolution rates of K-Cr(VI)-jarosites: kinetic analysis and implications.

PubMed

Reyes, Iván A; Mireles, Ister; Patiño, Francisco; Pandiyan, Thangarasu; Flores, Mizraim U; Palacios, Elia G; Gutiérrez, Emmanuel J; Reyes, Martín

2016-01-01

The presence of natural and industrial jarosite type-compounds in the environment could have important implications in the mobility of potentially toxic elements such as lead, mercury, arsenic, chromium, among others. Understanding the dissolution reactions of jarosite-type compounds is notably important for an environmental assessment (for water and soil), since some of these elements could either return to the environment or work as temporary deposits of these species, thus would reduce their immediate environmental impact. This work reports the effects of temperature, pH, particle diameter and Cr(VI) content on the initial dissolution rates of K-Cr(VI)-jarosites (KFe3[(SO4)2 - X(CrO4)X](OH)6). Temperature (T) was the variable with the strongest effect, followed by pH in acid/alkaline medium (H3O(+)/OH(-)). It was found that the substitution of CrO4 (2-)in Y-site and the substitution of H3O(+) in M-site do not modify the dissolution rates. The model that describes the dissolution process is the unreacted core kinetic model, with the chemical reaction on the unreacted core surface. The dissolution in acid medium was congruent, while in alkaline media was incongruent. In both reaction media, there is a release of K(+), SO4 (2-) and CrO4 (2-) from the KFe3[(SO4)2 - X(CrO4)X](OH)6 structure, although the latter is rapidly absorbed by the solid residues of Fe(OH)3 in alkaline medium dissolutions. The dissolution of KFe3[(SO4)2 - X(CrO4)X](OH)6 exhibited good stability in a wide range of pH and T conditions corresponding to the calculated parameters of reaction order n, activation energy E A and dissolution rate constants for each kinetic stages of induction and progressive conversion. The kinetic analysis related to the reaction orders and calculated activation energies confirmed that extreme pH and T conditions are necessary to obtain considerably high dissolution rates. Extreme pH conditions (acidic or alkaline) cause the preferential release of K(+), SO4 (2-) and CrO4 (2-) from the KFe3[(SO4)2 - X(CrO4)X](OH)6 structure, although CrO4 (2-) is quickly adsorbed by Fe(OH)3 solid residues. The precipitation of phases such as KFe3[(SO4)2 - X(CrO4)X](OH)6, and the absorption of Cr(VI) after dissolution can play an important role as retention mechanisms of Cr(VI) in nature.

Assessment of calcium addition on the removal of U(VI) in the alkaline conditions created by NH 3 gas

DOE PAGES

Katsenovich, Yelena; Cardona, Claudia; Szecsody, Jim; ...

2018-03-06

Remediation of uranium (U) contamination in the deep vadose zone (VZ) sediments abundant in calcite mineral is a challenging task considering the formation of highly stable and mobile uranyl complexes with carbonate and calcium in pore water composition. There is a concern that uranium contamination in the VZ can serve as a continued source for groundwater pollution, creating a risk to human health and the environment through the groundwater pathway. This requires in-situ remediation of the radionuclide-contaminated VZ to convert soluble U species to low solubility precipitates that are stable in the natural environment. Injection of reactive gasses (e.g., NHmore » 3) is a promising technology to decrease U mobility in the unsaturated zone without the addition of liquid amendments. The NH 3 injection creates alkaline conditions that can alter the sediment pore water composition due to a release of elements from minerals (via desorption and dissolution) that are present in the sediment. However, it is not known how VZ pore water constituents (Si, Al 3+, HCO 3 -, and Ca 2 +) would affect U(VI) removal/precipitation in alkaline conditions. This study quantified the role of major pore water constituents typically present in the arid and semi-arid environments of the western regions of the U.S and identified solid uranium-bearing phases that could potentially precipitate from solutions approximating pore water compositions after pH manipulations via ammonia gas injections. Triplicate samples were prepared using six Si (5, 50 100, 150, 200, and 250 mM), six HCO 3 - (0, 3, 25, 50, 75, and 100 mM), and two Ca 2+ (5 and 10 mM) concentrations. The concentration of aluminum and uranium was kept constant at 5 mM and 0.0084 mM, respectively, in all synthetic formulations tested. Results showed that the percentage of U(VI) removal was controlled by the Si/Al molar ratios and Ca 2+ concentrations. Regardless of the bicarbonate concentration tested, the percentage of U(VI) removed increased as the Si/Al ratios were increased. However, higher Ca concentrations correlated with higher U(VI) removal, ranging between 96% and 99%, at low Si/Al ratios. The SEM images of dried precipitates displayed dense amorphous regions high in silica content, where EDS elemental analysis unveiled higher U atomic percentages. The formation of uranyl silicate and carbonate minerals was also predicted by the speciation modeling. XRD analysis revealed the presence of uranyl carbonate mineral phases (andersonite, grimselite); however, uranyl silicates predicted (Na-boltwoodite) were not identified experimentally, possibly due to the amorphous nature of the silica solid phases observed in our experiments.« less

Study of Mo (VI) removal from aqueous solution: application of different mathematical models to continuous biosorption data.

PubMed

Kafshgari, Fatemeh; Keshtkar, Ali Reza; Mousavian, Mohammad Ali

2013-01-25

Molybdenum (VI) biosorption process was investigated by marine algae Cystoseria indica pretreated with 0.1 M CaCl2 solution in a packed bed column. The biosorbent was characterized by FTIR, BET and SEM analyses. The results showed that Mo (VI) ions should be chelated with the hydroxyl, carboxyl and amine groups of the biomass. The effects of inlet metal concentration and flow rate on biosorption process were investigated and the experimental breakthrough curves were obtained. Results showed that the maximum biosorption capacity of Ca-pretreated C. indica for Mo (VI) was found to be 18.32 mg/g at optimum flow rate of (1.4 mL/min). The controlled-rate step shifted from external to internal mass transfer limitations, as the flow rate increased. Also, it was observed that the breakthrough and exhaustion time decreased from 17.14 hr to 9.05 hr and from 0.006 h to 0.002 hr respectively, with the increase of flow rate from 0.7 to 2.1 ML/min. The increase in the initial concentration of Mo (VI) solution from 30 to 95 ml min-1 increases the adsorption capacity from 18.32 to 30.19 mg/g and decreases the percentage of Mo (VI) removal from 61 to 38%. Also, the treated volume was the greatest (1.42 L) at the lowest inlet concentration. Column data obtained under different conditions were described using the Thomas, Yoon and Nelson, Yan and Belter models. The breakthrough curve predictions by Belter model were found to be very satisfactory.

Combination of cathodic reduction with adsorption for accelerated removal of Cr(VI) through reticulated vitreous carbon electrodes modified with sulfuric acid-glycine co-doped polyaniline.

PubMed

Mo, Xi; Yang, Zhao-hui; Xu, Hai-yin; Zeng, Guang-ming; Huang, Jing; Yang, Xia; Song, Pei-pei; Wang, Li-ke

2015-04-09

Improving the reduction kinetics is crucial in the electroreduction process of Cr(VI). In this study, we developed a novel adsorption-electroreduction system for accelerated removal of Cr(VI) by employing reticulated vitreous carbon electrode modified with sulfuric acid-glycine co-doped polyaniline (RVC/PANI-SA-GLY). Firstly, response surface methodology confirmed the optimum polymerization condition of co-doped polyaniline for modifying electrodes (Aniline, sulfuric acid and glycine, respectively, of 0.2 mol/L, 0.85 mol/L, 0.93 mol/L) when untraditional dopant glycine was added. Subsequently, RVC/PANI-SA-GLY showed higher Cr(VI) removal percentages in electroreduction experiments over RVC electrode modified with sulfuric acid doped polyaniline (RVC/PANI-SA) and bare RVC electrode. In contrast to RVC/PANI-SA, the improvement by RVC/PANI-SA-GLY was more significant and especially obvious at more negative potential, lower initial Cr(VI) concentration, relatively less acidic solution and higher current densities, best achieving 7.84% higher removal efficiency with entire Cr(VI) eliminated after 900 s. Current efficiencies were likewise enhanced by RVC/PANI-SA-GLY under quite negative potentials. Fourier transform infrared (FTIR) and energy dispersive spectrometer (EDS) analysis revealed a possible adsorption-reduction mechanism of RVC/PANI-SA-GLY, which greatly contributed to the faster reduction kinetics and was probably relative to the absorption between protonated amine groups of glycine and HCrO4(-). Eventually, the stability of RVC/PANI-SA-GLY was proven relatively satisfactory. Copyright © 2015 Elsevier B.V. All rights reserved.

Defense Small Business Innovation Research Program (SBIR). Abstracts of Phase I Awards. 1986.

DTIC Science & Technology

1986-01-01

RELATIVE HUMIDITY AT TEMPERATURES FOUND IN ARCTIC ENVIRONMENTS. IT IS BASED ON THE OBSERVATION THAT CERTAIN FLUORESCENT AND PHOSPHORESCENT COMPOUNDS ...FREEDMAN TITLE: III-V COMPOUNDS TRACE ELEMENT PROFILE ANALYSIS USING LASER ASSISTED S PECTROSCOPY T 55 OFFICE: RADC/DOR A NOVEL MICROPROBE ANALYSIS...AND II-VI AND III-V COMPOUNDS . THESE ADVANTAGES MAKE THE LSCE TECHNIQUE PARTICULARY WELL SUITED TO THE DEPOSITION OF QUANTUM WELL AND SUPERLATT ICE

A Simple Constant-Current Neural Stimulator With Accurate Pulse-Amplitude Control

DTIC Science & Technology

2001-10-25

STIMULATOR The block diagram of the proposed neurostimulator is displayed in Figure 1. It consists of a pair of transformers followed by full-bridge...to 6%. Pulse-repetition ranges from 1Hz to 10Hz. Figure 1. Block diagram of the neurostimulator Voltage Regulator T 1 Astable T 2 V/I...discrete transistors. For explanatory reasons, the neurostimulator schematic is split into three main elements: the oscillator, the output V/I converter

Time Periodic Control of a Multi-Blade Helicopter.

DTIC Science & Technology

1988-05-01

part of an element of p X rotor inflow ratio; Langrangian multiplier; Poincare exponent H rotor inflow ratio with respect to the hub *P plane A...and a $ complex conjugate pair in the right- half plane resulting from ( the longitudinal velocity and pitch coupling. Without a horizontal tail, the ... Poincare Exponents . . .. 182 VI. Controller Gains ...... ................ 184 viii I ’Q List of Symbols Listed below are the principal symbols used in this

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

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

DUNCAM JB; GUTHRIE MD; LUECK KJ

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.

Experimente ueber den Einflusse von Metaboliten und Antimetaboliten am Modell von Trichomonas Vaginalis. VI. (Experiments on the Influence of Metabolites and Antimetabolites on the Model of Trichomonas Vaginalis. VI. Communication: Effect of Vitamins and Vitamin-Like Substances),

DTIC Science & Technology

A number of substances (folic acid, axerophtol, tokopherol and others) stimulate the growth of Trichomonas vaginalis and, therefore, are very well...group of vitamins (thiamine, lactoflavin, pyridoxine and others) are without recognizeable effect upon the growth of Trichomonas vaginalis . The third...inhibiting effect upon the growth of Trichomonas vaginalis . Further investigations with these substances within a combined inhibition system seem to be important. (Modified author abstract)

Investigation of corrosion of welded joints of austenitic and duplex stainless steels

NASA Astrophysics Data System (ADS)

Topolska, S.

2016-08-01

Investigation of corrosion resistance of materials is one of the most important tests that allow determining their functional properties. Among these tests the special group consist electrochemical investigations, which let to accelerate the course of the process. These investigations allow rapidly estimating corrosion processes occurring in metal elements under the influence of the analysed environment. In the paper are presented results of investigations of the resistance to pitting corrosion of the steel of next grades: austenitic 316L and duplex 2205. It was also analysed the corrosion resistance of welded joints of these grades of steel. The investigations were conducted in two different corrosion environments: in the neutral one (3.5 % sodium chloride) and in the aggressive one (0.1 M sulphuric acid VI). The obtained results indicate different resistance of analysed grades of steel and their welded joints in relation to the corrosion environment. The austenitic 316L steel characterizes by the higher resistance to the pitting corrosion in the aggressive environment then the duplex 2205 steel. In the paper are presented results of potentiodynamic tests. They showed that all the specimens are less resistant to pitting corrosion in the environment of sulphuric acid (VI) than in the sodium chloride one. The 2205 steel has higher corrosion resistance than the 316L stainless steel in 3.5% NaCl. On the other hand, in 0.1 M H2SO4, the 316L steel has a higher corrosion resistance than the 2205 one. The weld has a similar, very good resistance to pitting corrosion like both steels.

Elemental abundance analyses with coadded DAO spectrograms. VI - The mercury-manganese stars Nu Cancri, Iota Coronae Borealis and HR 8349

NASA Technical Reports Server (NTRS)

Adelman, Saul J.

1989-01-01

The elemental abundances of three mercury-manganese stars, Nu Cancri, Iota Coronae Borealis, and HR 8349, were found to be consistent with previous analyses of this series. As Iota CrB is a double-lined spectroscopic binary with a small velocity amplitude for most of its period, its study required determining whether the observed lines were produced in the primary or secondary or both. The derived abundances and effective termperatures were used along with those of mercury-manganese stars previously analyzed in order to extend the study of probable correlations between abundances, with the effective temperature and surface gravity in accordance with radiative diffusion explanations.

Pseudomonas aestusnigri sp. nov., isolated from crude oil-contaminated intertidal sand samples after the Prestige oil spill.

PubMed

Sánchez, David; Mulet, Magdalena; Rodríguez, Ana C; David, Zoyla; Lalucat, Jorge; García-Valdés, Elena

2014-03-01

Strains VGXO14(T) and Vi1 were isolated from the Atlantic intertidal shore from Galicia, Spain, after the Prestige oil spill. Both strains were Gram-negative rod-shaped bacteria with one polar inserted flagellum, strictly aerobic, and able to grow at 18-37°C, pH 6-10 and 2-10% NaCl. A preliminary analysis of the 16S rRNA and the partial rpoD gene sequences indicated that these strains belonged to the Pseudomonas genus but were distinct from any known Pseudomonas species. A polyphasic taxonomic approach including phylogenetic, chemotaxonomic, phenotypic and genotypic data confirmed that the strains belonged to the Pseudomonas pertucinogena group. In a multilocus sequence analysis, the similarity of VGXO14(T) and Vi1 to the closest type strain of the group, Pseudomonas pachastrellae, was 90.4%, which was lower than the threshold of 97% established to discriminate species in the Pseudomonas genus. The DNA-DNA hybridisation similarity between strains VGXO14(T) and Vi1 was 79.6%, but below 70% with the type strains in the P. pertucinogena group. Therefore, the strains should be classified within the genus Pseudomonas as a novel species, for which the name Pseudomonas aestusnigri is proposed. The type strain is VGXO14(T) (=CCUG 64165(T)=CECT 8317(T)). Copyright © 2013 Elsevier GmbH. All rights reserved.

Research on chromium and arsenic speciation in atmospheric particulate matter: short review

NASA Astrophysics Data System (ADS)

Nocoń, Katarzyna; Rogula-Kozłowska, Wioletta; Widziewicz, Kamila

2018-01-01

Atmospheric particulate matter (PM) plays an important role in the distribution of elements in the environment. The PM-bound elements penetrates into the other elements of the environment, in two basic forms - those dissolved in the atmospheric precipitation and those permanently bound to PM particles. Those forms differs greatly in their mobility, thus posing a potential threat to living organisms. They can also be an immediate threat, while being inhaled. Chromium (Cr) and arsenic (As) belong to the group of elements whose certain chemical states exhibit toxic properties, that is Cr(VI) and As(III). Thus, recognition of the actual threat posed by Cr and As in the environment, including those present in PM, is possible only through the in depth speciation analysis. Research on the Cr and As speciation in PM, more than the analogous studies of their presence in other compartments of the environment, have been undertaken quite rarely. Hence the knowledge on the speciation of PM-bound As and Cr is still limited. The state of knowledge in the field of PM-bound Cr and As is presented in the paper. The issues related to the characterization and occurrence of Cr and As species in PM, the share of Cr and As species mass in different PM size fractions, and in PM of different origin is also summarized. The analytical techniques used in the speciation analysis of PM-bound Cr and As are also discussed. In the existing literature there is no data on the physical characteristics of Cr and As (bound to a different PM size fractions), and thus it still lack of data needed for a comprehensive assessment of the actual environmental and health threat posed by airborne Cr and As.

Cr(VI) reduction and immobilization by novel carbonaceous modified magnetic Fe3O4/halloysite nanohybrid.

PubMed

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

2016-05-15

In this work, a novel "Dumbbell-like" magnetic Fe3O4/Halloysite nanohybrid (Fe3O4/HNTs@C) with oxygen-containing organic group grafting on the surface of natural halloysite nanotubes (HNTs) and homogeneous Fe3O4 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 Fe3O4/halloysite nanohybrid exhibited higher adsorption ability with a maximum adsorption capacity of 132 mg/L at 303K, which is about 100 times higher than that of unmodified halloysite nanotubes. More importantly, with the reduction of Fe3O4 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. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of green seaweed biomass for MoVI sorption from contaminated waters. Kinetic, thermodynamic and continuous sorption studies.

PubMed

Bertoni, Fernando A; Medeot, Anabela C; González, Juan C; Sala, Luis F; Bellú, Sebastián E

2015-05-15

Spongomorpha pacifica biomass was evaluated as a new sorbent for Mo(VI) removal from aqueous solution. The maximum sorption capacity was found to be 1.28×10(6)±1×10(4) mg kg(-1) at 20°C and pH 2.0. Sorption kinetics and equilibrium studies followed pseudo-first order and Langmuir adsorption isotherm models, respectively. FTIR analysis revealed that carboxyl and hydroxyl groups were mainly responsible for the sorption of Mo(VI). SEM images show that morphological changes occur at the biomass surface after Mo(VI) sorption. Activation parameters and mean free energies obtained with Dubinin-Radushkevich isotherm model demonstrate that the mechanism of sorption process was chemical sorption. Thermodynamic parameters demonstrate that the sorption process was spontaneous, endothermic and the driven force was entropic. The isosteric heat of sorption decreases with surface loading, indicating that S. pacifica has an energetically non-homogeneous surface. Experimental breakthrough curves were simulated by Thomas and modified dose-response models. The bed depth service time (BDST) model was employed to scale-up the continuous sorption experiments. The critical bed depth, Z0 was determined to be 1.7 cm. S.pacifica biomass showed to be a good sorbent for Mo(VI) and it can be used in continuous treatment of effluent polluted with molybdate ions. Copyright © 2015 Elsevier Inc. All rights reserved.

ViDiT-CACTUS: an inexpensive and versatile library preparation and sequence analysis method for virus discovery and other microbiology applications.

PubMed

Verhoeven, Joost Theo Petra; Canuti, Marta; Munro, Hannah J; Dufour, Suzanne C; Lang, Andrew S

2018-04-19

High-throughput sequencing (HTS) technologies are becoming increasingly important within microbiology research, but aspects of library preparation, such as high cost per sample or strict input requirements, make HTS difficult to implement in some niche applications and for research groups on a budget. To answer these necessities, we developed ViDiT, a customizable, PCR-based, extremely low-cost (<5 US dollars per sample) and versatile library preparation method, and CACTUS, an analysis pipeline designed to rely on cloud computing power to generate high-quality data from ViDiT-based experiments without the need of expensive servers. We demonstrate here the versatility and utility of these methods within three fields of microbiology: virus discovery, amplicon-based viral genome sequencing and microbiome profiling. ViDiT-CACTUS allowed the identification of viral fragments from 25 different viral families from 36 oropharyngeal-cloacal swabs collected from wild birds, the sequencing of three almost complete genomes of avian influenza A viruses (>90% coverage), and the characterization and functional profiling of the complete microbial diversity (bacteria, archaea, viruses) within a deep-sea carnivorous sponge. ViDiT-CACTUS demonstrated its validity in a wide range of microbiology applications and its simplicity and modularity make it easily implementable in any molecular biology laboratory, towards various research goals.

Differential distribution of annexins-I, -II, -IV, and -VI in synovium.

PubMed Central

Goulding, N J; Dixey, J; Morand, E F; Dodds, R A; Wilkinson, L S; Pitsillides, A A; Edwards, J C

1995-01-01

OBJECTIVES--To examine the distribution of four annexins in non-inflamed rheumatoid arthritic and osteoarthritic synovial tissue. METHODS--Frozen sections were stained with monoclonal antibodies (MAb) specific for annexins-I, -II, -IV, and -VI, and for cell lineage related markers including CD68 and CD14 (macrophages), prolyl hydroxylase (fibroblasts), and CD3 (T cells). RESULTS--Each of the annexins was present in synovial tissues in significant amounts in the three groups studied. Annexin-I was predominantly found within the synovial lining layer and double labelling showed it to be present predominantly in cells of the macrophage lineage. In rheumatoid specimens there was increased staining within the lining layer, perivascularly and on macrophages within the tissue stroma. Annexin-II was present in a distribution similar to that of annexin-I, but with more prominent perivascular staining. Annexins-IV and -VI were seen chiefly in association with areas of lymphocyte infiltration in rheumatoid tissue, whereas annexins-I and -II were absent from these areas. Endothelial cells stained weakly positive for annexins-I and -II, and more strongly for -IV and -VI. CONCLUSIONS--This study demonstrates that annexins (particularly annexin-I, a putative mediator of the anti-inflammatory activities of glucocorticoids) are abundant in rheumatoid and non-rheumatoid synovial tissue, annexins-IV and -VI having a distribution distinct from that of -I and -II. Images PMID:7492225

Surface Engineering of PAMAM-SDB Chelating Resin with Diglycolamic Acid (DGA) Functional Group for Efficient Sorption of U(VI) and Th(IV) from Aqueous Medium.

PubMed

Ilaiyaraja, P; Deb, A K Singha; Ponraju, D; Ali, Sk Musharaf; Venkatraman, B

2017-04-15

A novel chelating resin obtained via growth of PAMAM dendron on surface of styrene divinyl benzene resin beads, followed by diglycolamic acid functionalization of the dendrimer terminal. Batch experiments were conducted to study the effects of pH, nitric acid concentration, amount of adsorbent, shaking time, initial metal ion concentration and temperature on U(VI) and Th(IV) adsorption efficiency. Diglycolamic acid terminated PAMAM dendrimer functionalized styrene divinylbenzene chelating resin (DGA-PAMAM-SDB) is found to be an efficient candidate for the removal of U(VI) and Th(IV) ions from aqueous (pH >4) and nitric acid media (>3M). The sorption equilibrium could be reached within 60min, and the experimental data fits with pseudo-second-order model. Langmuir sorption isotherm model correlates well with sorption equilibrium data. The maximum U(VI) and Th(IV) sorption capacity onto DGA-PAMAMG 5 -SDB was estimated to be about 682 and 544.2mgg -1 respectively at 25°C. The interaction of actinides and chelating resin is reversible and hence, the resin can be regenerated and reused. DFT calculation on the interaction of U(VI) and Th(IV) ions with chelating resin validates the experimental findings. Copyright © 2017 Elsevier B.V. All rights reserved.

TOPICAL REVIEW: The shallow-to-deep instability of hydrogen and muonium in II VI and III V semiconductors

NASA Astrophysics Data System (ADS)

Cox, S. F. J.

2003-11-01

The structure and electrical activity of monatomic hydrogen defect centres are inferred from the spectroscopy and charge-state transitions of muonium, the light pseudo-isotope of hydrogen. Introductions are given to all these topics. Special attention is paid to the shallow-donor behaviour recently established in a number of II VI compounds and one III nitride. This contrasts with trapped-atom states suggestive of an acceptor function in other members of the II VI family as well as with the deep-level amphoteric behaviour which has long been known in the elemental group-IV semiconductors and certain III V compounds. The systematics of this remarkable shallow-to-deep instability are examined in terms of simple chemical considerations, as well as current theoretical and computational models. The muonium data appear to confirm predictions that the switch from shallow to deep behaviour is governed primarily by the depth of the conduction-band minimum below the vacuum continuum. The threshold electron affinity is around 3.5 eV, which compares favourably with computational estimates of a so-called pinning level for hydrogen (+/-) charge-state transitions of between -3 and -4.5 eV. A purely ionic model gives some intuitive understanding of this behaviour as well as the invariance of the threshold. Another current description applies equally to covalent materials and relates the threshold to the origin of the electrochemical scale. At the present level of approximation, zero-point energy corrections to the transition levels are small, so that muonium data should provide a reliable guide to the behaviour of hydrogen. Muonium spectroscopy proves to be more sensitive to the (0/+) donor level than to the (+/-) pinning level but, as a tool which does not rely on favourable hydrogen solubility, it looks set to test further predictions of these models in a large number of other materials, notably oxides. Certain candidate thin-film insulators and high-permittivity gate dielectrics appear to be uncomfortably close to conditions in which hydrogen impurity may cause electronic conduction.

Fractionation of uranium isotopes in minerals screened by gamma spectrometry.

NASA Astrophysics Data System (ADS)

Geiger, Jeffrey L.; Baldwin, Austin M.; Blatchley, Charles C.

2008-03-01

At least two groups have reported finding shifts in the ratio of U-235/U-238 for sandstone, black shale, and other sedimentary samples using precision ICP-MS. These shifts were tentatively attributed to a recently predicted isotope effect based on nuclear volume that causes fractionation for U^IV-U^VI transitions. However, fractionation of high Z elements may be less likely an explanation than U-235 depletion induced by galactic cosmic ray neutrons. Isotope depletion in marine sediments could therefore be an indicator of changes in cosmic ray flux due to nearby supernovae, gamma-ray bursts, or longer term changes during the 62 million year cycle of the Sun above and below the galactic plane. We report using a less precise approach than ICP-MS, but one which can quickly screen samples to look for anomalies in isotope ratios, namely HPGe gamma ray spectrometry. Various levels of depletion were measured for uranium rich minerals, including brannerite, carnotite, and pitchblende, as well as coal and limestone samples.

High-pressure phase transitions, amorphization, and crystallization behaviors in Bi2Se3.

PubMed

Zhao, Jinggeng; Liu, Haozhe; Ehm, Lars; Dong, Dawei; Chen, Zhiqiang; Gu, Genda

2013-03-27

The phase transition, amorphization, and crystallization behaviors of the topological insulator bismuth selenide (Bi2Se3) were discovered by performing in situ high-pressure angle-dispersive x-ray diffraction experiments during an increasing, decreasing, and recycling pressure process. In the compression process, Bi2Se3 transforms from the original rhombohedral structure (phase I(A)) to a monoclinic structure (phase II) at about 10.4 GPa, and further to a body-centered tetragonal structure (phase III) at about 24.5 GPa. When releasing pressure to ambient conditions after the complete transformation from phase II to III, Bi2Se3 becomes an amorphous solid (AM). In the relaxation process from this amorphous state, Bi2Se3 starts crystallizing into an orthorhombic structure (phase I(B)) about five hours after releasing the pressure to ambient. A review of the pressure-induced phase transition behaviors of A2B3-type materials composed from the V and VI group elements is presented.

Direct evidence for As as a Zn-site impurity in ZnO.

PubMed

Wahl, U; Rita, E; Correia, J G; Marques, A C; Alves, E; Soares, J C

2005-11-18

Arsenic has been reported in the literature as one of the few p-type dopants in the technologically promising II-VI semiconductor ZnO. However, there is an ongoing debate whether the p-type character is due to As simply replacing O atoms or to the formation of more complicated defect complexes, possibly involving As on Zn sites. We have determined the lattice location of implanted As in ZnO by means of conversion-electron emission channeling from radioactive (73)As. In contrast to what one might expect from its nature as a group V element, we find that As does not occupy substitutional O sites but in its large majority substitutional Zn sites. Arsenic in ZnO (and probably also in GaN) is thus an interesting example for an impurity in a semiconductor where the major impurity lattice site is determined by atomic size and electronegativity rather than its position in the periodic system.

Detection of Nitrogen and Neon in the X-ray Spectrum of GP Com with XMM/Newton

NASA Technical Reports Server (NTRS)

Strohmayer, Tod E.

2004-01-01

We report on X-ray spectroscopic observations with XMM/Newton of the ultra-compact, double white dwarf binary, GP Com. With the Reflection Grating Spectrometers (RGS) we detect the L(alpha) and L(beta) lines of hydrogen-like nitrogen (N VII) and neon (Ne X), as well as the helium-like triplets (N VI and Ne IX) of these same elements. All the emission lines are unresolved. These are the first detections of X-ray emission lines from a double-degenerate, AM CVn system. We detect the resonance (r) and intercombination (i) lines of the N VI triplet, but not the forbidden (f) line. The implied line ratios for N VI, R = f/i less than 0.3, and G = (f + i ) / r approx. = 1, combined with the strong resonance line are consistent with a dense, collision-dominated plasma. Both the RGS and EPIC/MOS spectra are well fit by emission horn an optically thin thermal plasma with an emission measure (EM) is a member of (kT/6.5 keV)(sup 0.8) (model cevmkl in XSPEC). Helium, nitrogen, oxygen and neon are required to adequately model the spectrum, however, the inclusion of sulphur and iron further improves the fit, suggesting these elements may also be present at low abundance. We confirm in the X-rays the under- abundance of both carbon and oxygen relative to nitrogen, first deduced from optical spectroscopy by Marsh et al. The average X-ray luminosity of approx. = 3 x 10(exp 30) ergs/s implies a mass accretion rate dot-m approx. = 9 x 10(exp -13) solar mass/yr. The implied temperature and density of the emitting plasma, combined with the presence of narrow emission lines and the low dot-m value, are consistent with production of the X-ray emission in an optically thin boundary layer just above the surface of the white dwarf.

Comparing the Impact of Refractive and Non-Refractive Vision Loss on Functioning and Disability: The Salisbury Eye Evaluation

PubMed Central

Zebardast, Nazlee; Swenor, Bonnielin K.; van Landingham, Suzanne W.; Massof, Robert W.; Munoz, Beatriz; West, Sheila K.; Ramulu, Pradeep Y.

2015-01-01

Purpose To compare the effects of uncorrected refractive error (URE) and non-refractive visual impairment (VI) on performance and disability measures. Design Cross-sectional population-based study. Participants 2469 individuals with binocular presenting visual acuity (PVA) of 20/80 or better who participated in the first round of the Salisbury Eye Evaluation study. Methods URE was defined as binocular PVA of 20/30 or worse, improving to better than 20/30 with subjective refraction. VI was defined as post-refraction binocular best corrected visual acuity (BCVA) of 20/30 or worse. The visual acuity decrement attributable to VI was calculated as the difference between BCVA and 20/30 while that due to URE was taken as the difference between PVA and BCVA. Multivariable regression analyses were used to assess the disability impact of 1) vision status (VI, URE, or normal vision) using the group with normal vision as reference, and 2) a one-line decrement in acuity due to VI or URE. Main Outcome Measures Objective measures of visual function were obtained from timed performance of mobility and near vision tasks, self-reported driving cessation, and self-reported visual difficulty measured by the Activities of Daily Vision (ADV) scale. ADV responses were analyzed using Rasch analysis to determine visual ability. Results Compared to individuals with normal vision, subjects with VI (n=191) had significantly poorer objective and subjective visual functioning in all metrics examined (p<0.05) while subjects with URE (n=132) demonstrated slower walking speeds, slower near task performance, more frequent driving cessation and lower ADV scores (p<0.05), but did not demonstrate slower stair climbing or descent speed. For all functional metrics evaluated, the impact of VI was greater than the impact of URE. The impact of a one-line VA decrement due to VI was associated with greater deficits in mobility measures and driving cessation when compared to a one-line VA decrement due to URE. Conclusions VI is associated with greater disability than URE across a wide variety of functional measures, even in analyses adjusting for the severity of vision loss. Refractive and non-refractive vision loss should be distinguished in studies evaluating visual disability, and should be understood to have differing consequences. PMID:25813453

Preparation and Cr(VI) removal performance of corncob activated carbon.

PubMed

Li, Hongyan; Gao, Pei; Cui, Jianguo; Zhang, Feng; Wang, Fang; Cheng, Jici

2018-05-12

Corncob activated carbon (CCAC) was prepared by a H 3 PO 4 activation method. The optimum conditions for the preparation of CCAC were determined by orthogonal experiments. The effects of pH, reaction time, CCAC dosage, and hexavalent chromium (Cr(VI)) concentrations on Cr(VI) removal by CCAC were studied. Corn straw activated carbon (CSAC) was also prepared using the optimum preparation conditions determined for CCAC. The properties of samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The results showed that the optimum preparation conditions for CCAC were as follows: a mass of corncob of 10 g; a mass ratio of corncob to H 3 PO 4 of 1:2; a 5% H 3 BO 3 content of 10 mL; an impregnation time of 45 min; a carbonization temperature of 500 °C. The optimum conditions for the removal of Cr(VI) were as follows: pH < 9; temperature, 308 K; rotation speed, 150 r min -1 ; reaction time, 60 min; CCAC dosage, 1 g L -1 . The Cr(VI) removal rate was above 98%, and the maximum adsorption capacity of CCAC was 9.985 mg g -1 . The concentration of residual Cr(VI) in water was less than 0.05 mg L -1 . FTIR showed that the surfaces of the samples had more oxygen-containing functional groups, which promoted the adsorption. XRD showed that CCAC and CSAC had similar peaks and that these peaks promoted the adsorption of Cr(VI). BET indicated that the number of pores in the samples followed the order CCAC > CSAC > CAC. SEM showed that the CCAC surface had a more porous structure, which enhanced adsorption. EDS showed that the C contents of CCAC and CSAC were much higher than that of CAC. Cr(VI) adsorption on CCAC followed quasi-second-order kinetics and was in accordance with a Langmuir adsorption isotherm, with monolayer adsorption. The adsorption reaction was endothermic, where higher temperatures increased the degree of spontaneous reaction.

Accumulation, depuration dynamics and effects of dissolved hexavalent chromium in juvenile Japanese medaka (Oryzias latipes).

PubMed

Chen, Hongxing; Guo, Zhongbao; Zhou, Yu; Li, Dan; Mu, Lei; Klerks, Paul L; Luo, Yongju; Xie, Lingtian

2018-02-01

We previously demonstrated that chronic exposure to hexavalent chromium (Cr(VI)) causes a variety of adverse effects in the Japanese medaka (Oryzias latipes). The present study investigated the transition of acute to chronic effects by assessing the influences of Cr(VI) exposure concentration and exposure duration on Cr accumulation and their effects on fish growth and antioxidant physiology. Juvenile fish were exposed to 0.05, 0.5, 4 or 8mg/L Cr(VI) for 28 days. Endpoints were evaluated on days 3, 7, 14, 21 and 28. In addition, Cr depuration was examined for fish from two exposure groups (0.5 and 8mg/L). Chromium accumulation was rapid initially, then continued at a slower rate till the end of the exposure period without showing signs of reaching a steady state. Depuration patterns differed between the two exposure groups, but both reached 50% in 14 days. The rapid initial accumulation was accompanied by increased lipid peroxidation and elevated activities of antioxidants (e.g., GST, SOD and CAT). Activities of these enzymes had mostly returned to baseline levels by day 7, but there was no evidence of further cellular damage from ROS. Effects on fish length and weight continued to be evident over the 28-day exposure period. Our study suggest that the initial effects of Cr(VI) exposure may not be a good predictor of more-chronic effects in fish as a consequence of an efficient acclimation response by the antioxidant system that limits ROS-mediated toxicity. Copyright © 2017 Elsevier Inc. All rights reserved.

Occupational exposure to Cr(VI): comparison between chromium levels in lymphocytes, erythrocytes, and urine.

PubMed

Lukanova, A; Toniolo, P; Zhitkovich, A; Nikolova, V; Panev, T; Popov, T; Taioli, E; Costa, M

1996-01-01

The relationships between chromium (Cr) levels in lymphocytes, erythrocytes, urine, and ambient air were compared among 14 chrome-platers from a metallurgic plant in Bulgaria and two groups of local controls, one from the same heavily polluted industrial town as the chrome-platers (n = 11) and one from a seaside resort town 100 km away (n = 6). Among the chrome-platers, the Cr concentration in peripheral lymphocytes was positively correlated with total Cr and Cr(VI) levels in ambient air and with Cr excretion in urine. As compared to the controls, the chrome-platers had mean Cr levels in lymphocytes twice as high, in erythrocytes ninefold higher, and in urine fourfold to eightfold higher. Although Cr levels in urine and lymphocytes were similar between the two control groups, levels in erythrocytes were 3 times higher among subjects from the industrial area than among those from the seaside town. The study suggests that lymphocyte Cr could be a good indicator of the Cr body burden caused by high exposures to Cr(VI), such as in electroplating operations. In these conditions, erythrocyte Cr may be less useful, possibly owing to increased toxicity due to the high affinity of erythrocytes for Cr. However, when exposure is lower, such as in most environmental situations, erythrocyte Cr should provide a better and more sensitive index than lymphocyte Cr. By contrast, urinary Cr, which provides information on total Cr exposure, including Cr(III) from dietary and environmental sources, does not seem to be of value for studying occupational exposure to Cr(VI).

Seeing it my way: living with childhood onset visual disability.

PubMed

Tadić, V; Hundt, G Lewando; Keeley, S; Rahi, J S

2015-03-01

Although the significant impact of visual disability in childhood has been widely recognized, children's own perspectives of living with a visual impairment have not been considered. We report the experiences of visually impaired (VI) children and young people aged 10-15 years about growing up with impaired sight. The participants were 32 VI children and young people, aged 10-15 years [visual acuity logarithm of minimum angle of resolution (LogMAR) worse than 0.51] recruited through National Health Service (NHS) paediatric ophthalmology and developmental vision clinics and 11 VI pupils aged 12-17 attending a specialist school for pupils with disabilities. Individual semi-structured interviews with participants captured their experiences of living with a visual impairment. A child-centred interview topic guide was developed from a literature review, observations at ophthalmology clinics, consultation with health and education professionals working with VI children and young people, and interviews and a focus group with VI pupils from the specialist school. Collaborative qualitative thematic analysis by three researchers identified emergent themes. NVivo software was used for coding the data. Analysis identified six themes concerning living with a visual impairment: (i) social relationships, participation and acceptance; (ii) independence and autonomy; (iii) psychological and emotional well-being; (iv) aspirations and concerns about the future; (v) functioning - home, school and leisure; and (vi) treatment of eye condition. Key issues included: the importance of family and peer support; balancing independence, support and safety; the emotional burden and adjustment of living with a disability; concerns about education and job prospects in the future; functional restrictions and limitations; and ongoing management of the eye condition. The findings offer insights into the complex realities of living with visual impairment. They provide the basis for development of patient-reported outcome measures. They can also serve to help enrich the understanding of health professionals working with VI children and young people, potentially enabling them to better support them. © 2014 John Wiley & Sons Ltd.

Inclusion of extremes of prematurity in ventricular index centile charts.

PubMed

Boyle, M; Shim, R; Gnanasekaran, R; Tarrant, A; Ryan, S; Foran, A; McCallion, N

2015-06-01

To assess the relationship between ventricular index (VI) measurements and postmenstrual age in preterm infants and to generate centile charts and normal ranges for frontal horn ratio (FHR) for a large contemporary cohort of preterm infants. A retrospective cohort study of 253 infants with birth gestation less than 32 weeks admitted between January 2009 and December 2011 to a tertiary NICU in Ireland. A total of 816 cranial ultrasounds were reviewed. Data collected were grouped according to postmenstrual age at the time of scan from 23 weeks to 45 weeks. Median values for VI show a general trend to increase with gestation. FHR did not significantly change with postmenstrual age at scan with a median value of 0.31. There is a slight increase in VI as gestation at the time of scans increases. These results provide the basis for updated centile charts which we propose for current practice.

Removal combined with reduction of hexavalent chromium from aqueous solution by Fe-ethylene glycol complex microspheres

NASA Astrophysics Data System (ADS)

Zhang, Yong-Xing; Jia, Yong

2016-12-01

Three-dimensional Fe-ethylene glycol (Fe-EG) complex microspheres were synthesized by a facile hydrothermal method, and were characterized by field emission scanning electron microscopy and transmission electron microscopy. The adsorption as well as reduction properties of the obtained Fe-EG complex microspheres towards Cr(VI) ions were studied. The experiment data of adsorption kinetic and isotherm were fitted by nonlinear regression approach. In neutral condition, the maximum adsorption capacity was 49.78 mg g-1 at room temperature, and was increased with the increasing of temperature. Thermodynamic parameters including the Gibbs free energy, standard enthalpy and standard entropy revealed that adsorption of Cr(VI) was a feasible, spontaneous and endothermic process. Spectroscopic analysis revealed the adsorption of Cr(VI) was a physical adsorption process. The adsorbed CrO42- ions were partly reduced to Cr(OH)3 by Fe(II) ions and the organic groups in the Fe-EG complex.

Heptavalent Neptunium in a Gas-Phase Complex: (Np VIIO 3 +)(NO 3 –) 2

DOE PAGES

Dau, Phuong D.; Maurice, Remi; Renault, Eric; ...

2016-09-15

A central goal of chemistry is to achieve ultimate oxidation states, including in gas-phase complexes with no condensed phase perturbations. In the case of the actinide elements, the highest established oxidation states are labile Pu(VII) and somewhat more stable Np(VII). We have synthesized and characterized gas-phase AnO 3(NO 3) 2- complexes for An = U, Np, and Pu by endothermic NO 2 elimination from AnO 2(NO 3) 3-. It was previously demonstrated that the PuO 3+ core of PuO 3(NO 3) 2- has a Pu—O• radical bond such that the oxidation state is Pu(VI); it follows that in UO 3(NOmore » 3) 2- it is the stable U(VI) oxidation state. On the basis of the relatively more facile synthesis of NpO 3(NO 3) 2-, a Np(VII) oxidation state is inferred. This interpretation is substantiated by reactivity of the three complexes: NO 2 spontaneously adds to UO 3(NO 3) 2- and PuO 3(NO 3) 2- but not to NpO 3(NO 3) 2-. This unreactive character is attributed to a Np(VII)O 3+ core with three stable Np=O bonds, this in contrast to reactive U—O• and Pu—O• radical bonds. The computed structures and reaction energies for the three AnO 3(NO 3) 2- support the conclusion that the oxidation states are U(VI), Np(VII), and Pu(VI). These results establish the extreme Np(VII) oxidation state in a gas-phase complex, and demonstrate the inherently greater stability of Np(VII) versus Pu(VII).« less

Simultaneous leaching of arsenite, arsenate, selenite and selenate, and their migration in tunnel-excavated sedimentary rocks: I. Column experiments under intermittent and unsaturated flow.

PubMed

Tabelin, Carlito Baltazar; Sasaki, Ryosuke; Igarashi, Toshifumi; Park, Ilhwan; Tamoto, Shuichi; Arima, Takahiko; Ito, Mayumi; Hiroyoshi, Naoki

2017-11-01

Rocks excavated in tunnel construction projects for roads and railways throughout Japan often leached out hazardous trace elements like arsenic (As) and selenium (Se) upon their exposure to the environment. In nature, the various oxyanionic species of As and Se not only coexist but also exhibit contrasting adsorption-desorption behaviors, so speciation is a crucial factor in their migration through natural geologic media. In this study, the leaching and transport of arsenite (As III ), arsenate (As V ), selenite (Se IV ) and selenate (Se VI ) in four tunnel-excavated rocks from the Cretaceous-Paleocene Yezo forearc basin were investigated using laboratory column experiments supplemented by batch leaching experiments. The single- and consecutive-batch leaching results revealed that As III , As V , Se IV and Se VI were released simultaneously, which could be attributed to the rapid dissolution of trace evaporite salts found in the rocks. Arsenic in the leachates was also predominated by As V while Se IV and Se VI concentrations were nearly equal, which are both consistent with predictions of equilibrium Eh-pH diagrams. Under intermittent and unsaturated flow, however, periods when As III and Se VI predominated in the effluents were observed. Spatial distributions of As and Se species with depth at the end of the column experiments suggest that migrations of As III , As V and Se IV were delayed, the extent of which depended on the rock. These results indicate that migration and speciation of As and Se in the rocks are controlled by preferential adsorption-desorption reactions, the effects of which were most probably magnified by changes in the pH and concentrations of coexisting ions due to intermittent and unsaturated flow. Copyright © 2017 Elsevier Ltd. All rights reserved.

Genetic Identification of an Enzymatic Se(VI) Reduction Pathway

NASA Astrophysics Data System (ADS)

Yee, N.; Kobayashi, D. Y.

2006-12-01

Enterobacter cloacae is a biofilm-forming organism that colonizes the subterranean portions of plants. Because of its ability to catalyze the reduction of selenium oxyanions, this bacterium plays an important role in Se(0) biomineralization and Se cycling in soils. Identification of the genes that regulate selenate reductase activity is needed to elucidate the mechanisms employed by this organism to reduce Se(VI). However, the genes in E. cloacae involved in selenium reduction are currently unknown. In this study, transposon mutagenesis and direct cloning techniques were used to identify genetic regions in E. cloacae SLD1a-1 associated with selenate reductase activity. The mini-Tn5 transposon system was used to produce mutants that have lost the ability to reduce selenate. E. cloacae mutants and genomic library clones heterologously expressed in E. coli S17-1 were screened for activity on LB agar supplemented with sodium selenate. The rate of selenate reduction by the clones was measured in liquid minimal media, and the Se(0) minerals formed by the clones were examined using EXAFS, TEM, and XRD. The transposon mutagenesis experiments revealed that mutation of menaquinone biosynthesis genes inhibits selenate reduction. The direct cloning experiments showed that heterologous expression of the global anaerobic regulatory gene fnr from Enterobacter cloacae in the non Se-reducing strain E. coli S17-1 activated selenate reductase activity and the ability to precipitate Se(0) particles. Se(VI) reduction by E. coli S17-1 containing the fnr gene occurred at similar rates as E. cloacae and produced elemental selenium particles with identical morphologies and short range atomic order. These findings indicate that Se(VI) reduction by facultative anaerobes is regulated by anaerobic electron carriers and oxygen sensing transcription factors.

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

PubMed

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

2016-12-01

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