Health & Environmental Research Online (HERO)


Molybdenum (7439-98-7 )


21,129 References Were Found:

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Non-oxidative Coupling of Methane to Ethylene Using Mo2C/[B]ZSM-5

Authors: Sheng, H; Schreiner, EP; Zheng, W; Lobo, RF (2018) ChemPhysChem 19:504-511. HERO ID: 4272320

[Less] Methane non-oxidative coupling to ethylene was investigated on Mo2C/[B]ZSM-5 catalyst at 923 K and atmospheric . . . [More] Methane non-oxidative coupling to ethylene was investigated on Mo2C/[B]ZSM-5 catalyst at 923 K and atmospheric pressure. In contrast to Mo2C/[Al]ZSM-5 catalysts for methane aromatization, this material exhibits very high ethylene selectivity (>90 %) and low aromatics (benzene and naphthalene) selectivity. The much weaker Brønsted acidity of [B]ZSM-5 leads to a slow rate of ethylene oligomerization. The stability of the catalyst is greatly enhanced with 93 % of the initial reaction rate remaining after 18 h of time on stream. In-situ UV/VIS spectra indicate that prior to carburization, mono/binuclear Mo oxides are initially well dispersed onto the zeolite support. Mo carbides clusters, formed during carburization with methane, appear similar to clusters formed in [Al]ZSM-5, as indicated by the X-ray Absorption Spectroscopy (XAS) data.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Electrically tunable optical properties of few layers black arsenic phosphorus

Authors: Yu, L; Zhu, Z; Gao, A; Wang, J; Miao, F; Shi, Y; Wang, X (2018) Nanotechnology. HERO ID: 4830887

[Less] Black arsenic phosphorus(b-AsP) is a promising two-dimensional material for various optoelectronic applications, . . . [More] Black arsenic phosphorus(b-AsP) is a promising two-dimensional material for various optoelectronic applications, bridging the wavelength gap between TMD (two-dimensional molybdenum disulfide) and graphene. Especially, it has intriguing potential in photo detectors and great advantages in mid infrared field. Yet, its optoelectronic modulation is open to be elucidated, which requires a fundamental understanding of its field effect optical modulation. Here, we reported the measurements of the lower-energy infrared anisotropic optical response of thin black arsenic phosphorus under different electrical gating. We reveal that in addition to band edge absorption, amplitude modulation of sub-band absorption up to ten percent is also obtained in reflection extinction. These in-gap absorptions are attributed to spin-orbital coupling and free carrier absorption. Our results suggest the important potential for use of black arsenic phosphorus in mid-infrared optoelectronic modulator applications.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Structural and mechanistic analysis of the arsenate respiratory reductase provides insight into environmental arsenic transformations

Authors: Glasser, NR; Oyala, PH; Osborne, TH; Santini, JM; Newman, DK (2018) HERO ID: 4839874

[Less] Arsenate respiration by bacteria was discovered over two decades ago and is catalyzed by diverse organisms . . . [More] Arsenate respiration by bacteria was discovered over two decades ago and is catalyzed by diverse organisms using the well-conserved Arr enzyme complex. Until now, the mechanisms underpinning this metabolism have been relatively opaque. Here, we report the structure of an Arr complex (solved by X-ray crystallography to 1.6-Å resolution), which was enabled by an improved Arr expression method in the genetically tractable arsenate respirer Shewanella sp. ANA-3. We also obtained structures bound with the substrate arsenate (1.8 Å), the product arsenite (1.8 Å), and the natural inhibitor phosphate (1.7 Å). The structures reveal a conserved active-site motif that distinguishes Arr [(R/K)GRY] from the closely related arsenite respiratory oxidase (Arx) complex (XGRGWG). Arr activity assays using methyl viologen as the electron donor and arsenate as the electron acceptor display two-site ping-pong kinetics. A Mo(V) species was detected with EPR spectroscopy, which is typical for proteins with a pyranopterin guanine dinucleotide cofactor. Arr is an extraordinarily fast enzyme that approaches the diffusion limit (Km = 44.6 ± 1.6 μM, kcat = 9,810 ± 220 seconds-1), and phosphate is a competitive inhibitor of arsenate reduction (Ki = 325 ± 12 μM). These observations, combined with knowledge of typical sedimentary arsenate and phosphate concentrations and known rates of arsenate desorption from minerals in the presence of phosphate, suggest that (i) arsenate desorption limits microbiologically induced arsenate reductive mobilization and (ii) phosphate enhances arsenic mobility by stimulating arsenate desorption rather than by inhibiting it at the enzymatic level.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Optimisation of laboratory arsenic analysis for groundwaters of West Bengal, India and possible water testing strategy

Authors: Kundu, AK; Majumder, S; Biswas, A; Bhowmick, S; Pal, C; Mukherjee, A; Majumder, M; Chatterjee, D (2018) HERO ID: 4845148

[Less] Regular monitoring of arsenic (As) in groundwater is crucial from public health perspectives as millions . . . [More] Regular monitoring of arsenic (As) in groundwater is crucial from public health perspectives as millions of people are suffering due to use of contaminated aquifer water for drinking purposes. The routine analyses, especially in developing nations, are mostly done in localised government/non-government laboratories with limited resources, having the target of analysing large number of samples in each run. Thus apart from analytical sensitivity, cost-effectiveness of the method and eco-friendliness of the experimental operation are key surreptitious factors. This demands optimisation of total As measurement methods and finding a method that gives optimum benefit' considering all these factors together. The present study therefore evaluates four common As (total) measurement methods [iodometric-colorimetric method, silver diethyl dithiocarbamate method, molybdenum blue method and hydride generation atomic absorption spectrophotometric (HG-AAS) method] practised in the Bengal Delta Plain, in view of their analytical sensitivity, related environmental hazard and experimental costs. It was found that the HG-AAS method is analytically more sensitive, whereas the iodometric-colorimetric method and the molybdenum blue method are better choices in terms of eco-friendliness and cost-effectiveness, respectively. However, when all three factors (analytical reliability, environmental hazard and cost) are considered simultaneously, the molybdenum blue method was found to be placed first in the optimum performance rank' list. It was also found that both environmental hazard and cost play a more crucial role than analytical reliability, although this is case specific and would differ from place to place around the globe. Finally based on the results, we have hypothesised a water testing strategy for developing countries such as India where the molybdenum blue method can be adapted as a screening method and later the HG-AAS method can be used to precisely identify the groundwater samples with As concentration below the WHO drinking water guideline value of 10g/L.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Atomistic simulation of cubic and tetragonal phases of U-Mo alloy: Structure and thermodynamic properties

Authors: Starikov, SV; Kolotova, LN; Kuksin, AYu; Smirnova, DE; Tseplyaev, VI (2018) HERO ID: 4724246

[Less] We studied structure and thermodynamic properties of cubic and tetragonal phases of pure uranium and . . . [More] We studied structure and thermodynamic properties of cubic and tetragonal phases of pure uranium and U-Mo alloys using atomistic simulations: molecular dynamics and density functional theory. The main attention was paid to the metastable gamma(0)-phase that is formed in U-Mo alloys at low temperature. Structure of gamma(0)-phase is similar to body-centered tetragonal (bct) lattice with displacement of a central atom in the basic cell along [001] direction. Such displacements have opposite orientations for part of the neighbouring basic cells. In this case, such ordering of the displacements can be designated as antiferrodisplacement. Formation of such complex structure may be interpreted through forming of short U-U bonds. At heating, the tetragonal structure transforms into cubic gamma(s)-phase, still showing ordering of central atom displacements. With rise in temperature, gamma(s)-phase transforms to gamma-phase with a quasi body-centered cubic (q-bcc) lattice. The local positions of uranium atoms in gamma-phase correspond to gamma(s)-phase, however, orientations of the central atom displacements become disordered. Transition from gamma(0) to gamma can be considered as antiferro-to paraelastic transition of order-disorder type.

This approach to the structure description of uranium alloy allows to explain a number of unusual features found in the experiments: anisotropy of lattice at low temperature; remarkably high selfdiffusion mobility in gamma-phase; decreasing of electrical resistivity at heating for some alloys. In addition, important part of this work is the development of new interatomic potential for U-Mo system made with taking into account details of studied structures. (C) 2017 Elsevier B.V. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Image fusion of Secondary Ion Mass Spectrometry and Energy-dispersive X-Ray Spectroscopy data for the characterization of uranium-molybdenum fuel foils

Authors: Willingham, D; Naes, BE; Tarolli, JayG; Schemer-Kohrn, A; Rhodes, M; Dahl, M; Guzman, A; Burkes, DE (2018) HERO ID: 4697537

[Less] Uranium-molybdenum (U-Mo) monolithic fuels represent one option for converting civilian research and . . . [More] Uranium-molybdenum (U-Mo) monolithic fuels represent one option for converting civilian research and test reactors operating with high enriched uranium (HEU) to low enriched uranium (LEU), effectively reducing the threat of nuclear proliferation world-wide. However, processes associated with fabrication of U-Mo monolithic fuels result in regions of elemental heterogeneity, observed as bands traversing the cross-section of representative samples. Isotopic variations (e.g., U-235 and U-238) could also be introduced because of associated processing steps, particularly since HEU feedstock is melted with natural or depleted uranium diluent to produce LEU. This study demonstrates the utility of correlative analysis of Energy-Dispersive X-ray Spectroscopy (EDS) and Secondary Ion Mass Spectrometry (SIMS) with their image data streams using image fusion, resulting in a comprehensive microanalytical characterization toolbox. Elemental and isotopic measurements were made on a sample from the Advanced Test Reactor (ATR) Full-sized plate In-center flux trap Position (AFIP)-7 experiment and compared to previous optical and electron microscopy results. The image fusion results are characteristic of SIMS isotopic maps, but with the spatial resolution of EDS images and, therefore, can be used to increase the effective spatial resolution of the SIMS imaging results to better understand homogeneity or heterogeneity that persists because of processing selections. Visual inspection using the image fusion methodology indicated slight variations in the 235U/238U ratio and quantitative analysis using the image intensities across several FoVs revealed an average 235U atom percent value of 17.9 +/- 2.4%, which was indicative of a non-uniform U isotopic distribution in the area sampled. Further development of this capability is useful for understanding the connections between the properties of LEU fuel alternatives and the ability to predict performance under irradiation. (C) 2017 Elsevier B.V. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Phosphonate and carboxylic acid co-functionalized MoS2 sheets for efficient sorption of uranium and europium: Multiple groups for broad-spectrum adsorption

Authors: Yang, S; Hua, M; Shen, L; Han, X; Xu, M; Kuang, L; Hua, D (2018) HERO ID: 4697682

[Less] It is significant to develop novel materials and techniques for efficient removal of radionuclides from . . . [More] It is significant to develop novel materials and techniques for efficient removal of radionuclides from radioactive wastes due to the radioactive and chemical toxicity. In this paper, we report a strategy for broad-spectrum adsorption of radionuclides by multiple groups-decorated adsorbents. Specifically, the adsorbents were prepared by grafting diethyl-(4-vinylbenzyl) phosphonate and maleic anhydride copolymers onto molybdenum disulfide sheets for the sorption of uranium(VI) and europium(III). The sorption efficiencies exhibited a dependency on pH, contact time and initial concentrations. The sorption reached the equilibrium within 60 min and followed a pseudo-second-order kinetic model. The maximum sorption capacities of the sorbents were 448.4 mg/g and 171.2 mg/g at pH 4.0 and 298.15 K for uranium(VI) and europium(III), respectively. The sorbent possessed a high efficiency of 98% in five sorption-desorption cycles without damage in chemical structures. XPS spectra showed that the sorption of uranium(VI) and europium(III) on the sorbents were originated from the interaction between multiple groups (such as sulfur, COOH, PO and PO) and uranium/europium. This work demonstrates that the adsorbent can be utilized as a promising material for the separation of broad-spectrum radionuclides from an aqueous solution.

Journal Article
Journal Article

Combined ab initio and empirical model of the thermal conductivity of uranium, uranium-zirconium, and uranium-molybdenum

Authors: Zhou, S; Jacobs, R; Xie, Wei; Tea, E; Hin, C; Morgan, D (2018) HERO ID: 4843645

[Less] In this work we developed a practical and general modeling approach for thermal conductivity of metals . . . [More] In this work we developed a practical and general modeling approach for thermal conductivity of metals and metal alloys that integrates ab initio and semiempirical physics-based models to maximize the strengths of both techniques. The approach supports creation of highly accurate, mechanistic, and extensible thermal conductivity modeling of alloys. The model was demonstrated on alpha-U and U-rich U-Zr and U-Mo alloys, which are potential fuels for advanced nuclear reactors. The safe use of U-based fuels requires quantitative understanding of thermal transport characteristics of the fuel. The model incorporated both phonon and electron contributions, displayed good agreement with experimental data over a wide temperature range, and provided insight into the different physical factors that govern the thermal conductivity under different temperatures. This model is general enough to incorporate more complex effects like additional alloying species, defects, transmutation products, and noble gas bubbles to predict the behavior of complex metallic alloys like U-alloy fuel systems under burnup.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Adsorption behavior of zirconium and molybdenum from nitric acid medium using low-cost adsorbent

Authors: Hamed, MM; Rizk, HE; Ahmed, IM (2018) HERO ID: 4301955

[Less] The highly radioactive waste liquors from the processing of nuclear reactor fuels contain zirconium . . . [More] The highly radioactive waste liquors from the processing of nuclear reactor fuels contain zirconium and molybdenum, which occur among the fission products. Treatment of wastewater by economical and effective methods is very crucial in the area of development and technological advancements. In the present work, the adsorption behavior of Zr(IV) and Mo(VI) on charcoal from nitric acid medium was investigated using batch technique. Variations of the distribution coefficients as a function of HNO3.concentration in the range 0.05-3.0 M were presented. Some of the separation possibilities were pointed out. The obtained results indicate that the selectivity of Zr(IV) is higher than Mo(VI) at high acidities. The adsorption kinetics data following the pseudo-second order model indicated that the rate-controlling step is chemical adsorption. The data also followed the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The values of enthalpy and entropy changes show that the overall adsorption process was endothermic (AH> 0) and increasing entropy (AS> 0), and it was spontaneous (Delta G < 0). This study shows that the low-cost adsorbent, charcoal, is an effective adsorbent for the retention of Zr(IV) and Mo(VI) species from nitric acid medium. The feasibility of the removal of Zr-95 and Mo-99 from simulated intermediate level waste solutions was tested. (C) 2017 Elsevier B.V. All rights reserved.

The "refereed" or "peer review" status of a journal comes from the Ulrichsweb Global Serials Directory (http://ulrichsweb.serialssolutions.com/), as supplied by the publisher. The term refers to the system of critical evaluation of manuscripts/articles by professional colleagues or peers. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. The peer-review and evaluation system is utilized to protect, maintain, and raise the quality of scholarly material published in serials. Publications subject to the referee process are assumed, then, to contain higher quality content than those that are not.
Peer Reviewed Journal Article

Heavy Ions Irradiation as a Tool to Minimize the Number of In-Pile Tests in UMo Fuel Development

Authors: Breitkreutz, H; Shi, J; Jungwirth, R; Zweifel, T; Chiang, HY; Petry, W (2018) HERO ID: 4724361

[Less] Irradiation with heavy ions from an accelerator source is an increasingly often used tool to quickly . . . [More] Irradiation with heavy ions from an accelerator source is an increasingly often used tool to quickly reproduce and simulate certain effects of in-pile irradiation tests, avoiding the complexity and high costs of handling highly radioactive samples. At the Maier-Leibnitz Laboratorium (MLL) of the Technische Universitat Munchen (TUM), swift heavy ions have been applied in the development of Uranium-Molybdenum (UMo) based research reactor fuels for more than 10 years. Since then, the technique has been advanced from feasibility over qualitative analysis to quantitative prediction, including fission gas implantation.