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Eseosa Asemota, Andrew J Scheman, Bruce A Brod
No abstract text is available yet for this article.
October 21, 2016: Dermatitis
Wenyue Li, Zhenyu Zhang, Yongbing Tang, Haidong Bian, Tsz-Wai Ng, Wenjun Zhang, Chun-Sing Lee
3D graphene-nanowall-decorated carbon felts (CF) are synthesized via an in situ microwave plasma enhanced chemical vapor deposition method and used as positive electrode for vanadium redox flow battery (VRFB). The carbon fibers in CF are successfully wrapped by vertically grown graphene nanowalls, which not only increase the electrode specific area, but also expose a high density of sharp graphene edges with good catalytic activities to the vanadium ions. As a result, the VRFB with this novel electrode shows three times higher reaction rate toward VO2(+)/VO(2+) redox couple and 11% increased energy efficiency over VRFB with an unmodified CF electrode...
April 2016: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Jong Ho Park, Jung Jin Park, O Ok Park, Jung Hoon Yang
Capacity decay in vanadium redox flow batteries during charge-discharge cycling has become an important issue because it lowers the practical energy density of the battery. The battery capacity tends to drop rapidly within the first tens of cycles and then drops more gradually over subsequent cycles during long-term operation. This paper analyzes and discusses the reasons for this early capacity decay. The imbalanced crossover rate of vanadium species was found to remain high until the total difference in vanadium concentration between the positive and negative electrolytes reached almost 1 mol dm(-3) ...
October 21, 2016: ChemSusChem
Ewa Kober, Zofia Janas, Julia Jezierska
A series of oxidovanadium(V) complexes [VO(L-κ(4)O,N,N,O)(OR)] (1a, R = Et, L = L(1); 1b, R = Me, L = L(1); 2, R = Me, L = L(2); 3, R = Me, L = L(3)) were synthesized by the σ-bond metathesis reaction between [VO(OR)3] and the linear diaminebis(phenol) derivatives H2L (salans) containing different para-substituents on the phenoxo group [CMe3CH2CMe2, L(1); Me, L(2); Cl, L(3)]. As shown by X-ray crystallography complexes 1a, 1b, and 2 exhibit cis-α geometry, do have a stereogenic vanadium center, and exist as a racemic mixture of the Δ cis-α and Λ cis-α enantiomers...
October 18, 2016: Inorganic Chemistry
Kaitlin A Doucette, Kelly N Hassell, Debbie C Crans
Improving efficacy and lowering resistance to metal-based drugs can be addressed by consideration of the coordination complex speciation and key reactions important to vanadium antidiabetic drugs or platinum anticancer drugs under biological conditions. The methods of analyses vary depending on the specific metal ion chemistry. The vanadium compounds interconvert readily, whereas the reactions of the platinum compounds are much slower and thus much easier to study. However, the vanadium species are readily differentiated due to vanadium complexes differing in color...
October 3, 2016: Journal of Inorganic Biochemistry
R Jiménez-Ballesta, F J García-Navarro, S Bravo, J A Amorós, C Pérez-de-Los-Reyes, M Mejías
Contamination of aquatic systems with potentially toxic trace elements (PTEs) is a major problem throughout the world. The National Park Tablas de Daimiel (NPTD) is considered to make up one of the two most important wetlands in the Biosphere Reserve called "Wet Spot." Since PTEs are good indicator of the prevailing environmental conditions and possible contamination, soil samples collected from 43 sites were analyzed in order to investigate the levels and its distribution of these elements, in the inundated floodplain area of the NPTD wetland...
October 14, 2016: Environmental Geochemistry and Health
Julio A Chirinos, Scott R Akers, Lien Trieu, Harry Ischiropoulos, Paschalis-Thomas Doulias, Ali Tariq, Izzah Vassim, Maheswara R Koppula, Amer Ahmed Syed, Haideliza Soto-Calderon, Raymond R Townsend, Thomas P Cappola, Kenneth B Margulies, Payman Zamani
BACKGROUND: Stable plasma nitric oxide (NO) metabolites (NOM), composed predominantly of nitrate and nitrite, are attractive biomarkers of NO bioavailability. NOM levels integrate the influence of NO-synthase-derived NO production/metabolism, dietary intake of inorganic nitrate/nitrite, and clearance of NOM. Furthermore, nitrate and nitrite, the most abundant NOM, can be reduced to NO via the nitrate-nitrite-NO pathway. METHODS AND RESULTS: We compared serum NOM among subjects without heart failure (n=126), subjects with heart failure and preserved ejection fraction (HFpEF; n=43), and subjects with heart failure and reduced ejection fraction (HFrEF; n=32)...
October 14, 2016: Journal of the American Heart Association
Luis Carlos de Vicente Poutás, Marta Castiñeira Reis, Roberto Sanz, Carlos Silva López, Olalla Nieto Faza
We propose a novel mechanism for the deoxydehydration (DODH) reaction of glycols catalyzed by a [Bu4N][VO2(dipic)] complex (dipic = pyridine-2,6-dicarboxylate) using triphenylphosphine as a reducing agent. Using density functional theory, we have confirmed that the preferred sequence of reaction steps involves reduction of the V(V) complex by phosphine, followed by condensation of the glycol into a [VO(dipic)(-O-CH2CH2-O-)] V(III) complex (6), which then evolves to the alkene product, with recovery of the catalyst...
October 14, 2016: Inorganic Chemistry
Zhaodong Li, Fei Wang, Xudong Wang
Vanadium oxide (VOx ) nanorods are uniformly synthesized on dense Si nanowire arrays. This 3D hierarchical nanoarchitecture offers a novel high-performance supercapacitor electrode design with significantly improved specific capacitance and high-rate capability.
October 14, 2016: Small
Jingting Zhu, Aibin Huang, Haibin Ma, Yining Ma, Kun Tong, Shidong Ji, Shanhu Bao, Xun Cao, Ping Jin
Vanadium dioxide (VO2), as a typical thermochromic material used in smart windows, is always limited by its weaker solar regulation efficiency (ΔTsol) and lower luminous transmittance (Tlum). Except for common approaches such as doping, coating and special structure, compositing is another effective method. The macroscopic thermochromic (from colorless to blue) ionic liquid-nickel-chlorine (IL-Ni-Cl) complexes are selected in this paper to be combined with VO2 nanoparticles forming a composite film. This novel scheme demonstrates outstanding optical properties: ΔTsol=26...
October 14, 2016: ACS Applied Materials & Interfaces
Mohammed Reza M Hashemi, Shang-Hua Yang, Tongyu Wang, Nelson Sepúlveda, Mona Jarrahi
Engineered metamaterials offer unique functionalities for manipulating the spectral and spatial properties of electromagnetic waves in unconventional ways. Here, we report a novel approach for making reconfigurable metasurfaces capable of deflecting electromagnetic waves in an electronically controllable fashion. This is accomplished by tilting the phase front of waves through a two-dimensional array of resonant metasurface unit-cells with electronically-controlled phase-change materials embedded inside. Such metasurfaces can be placed at the output facet of any electromagnetic radiation source to deflect electromagnetic waves at a desired frequency, ranging from millimeter-wave to far-infrared frequencies...
October 14, 2016: Scientific Reports
Kunfeng Chen, Dongfeng Xue
A novel and creative in-situ electrochemical activation method to transform vanadium ions to highly electroactive colloidal cathode in KOH solution under electric field has been designed. After undergoing electrochemical reaction, the in-situ functionalized vanadium-based colloidal cathode can adapt their geometrical structure to the high pseudocapacitive activity. The vanadium-based colloids //activated carbon asymmetric supercapcitor displays a high energy density of 50.4 Wh/kg at a power density of 250 W/kg, which is higher than the most reported vanadium-based supercapacitors...
October 14, 2016: ACS Applied Materials & Interfaces
Benjamin E Van Kuiken, Anselm W Hahn, Dimitrios Maganas, Serena DeBeer
Spectroscopic probes of the electronic structure of transition metal-containing materials are invaluable to the design of new molecular catalysts and magnetic systems. Herein, we show that 2p3d resonant inelastic X-ray scattering (RIXS) can be used to observe both spin-allowed and (in the V(III) case) spin-forbidden d-d excitation energies in molecular vanadium complexes. The spin-allowed d-d excitation energies determined by 2p3d RIXS are in good agreement with available optical data. In V(acac)3, a previously undetected spin-forbidden singlet state has been observed...
October 12, 2016: Inorganic Chemistry
Julie Besnardiere, Xavier Petrissans, François Ribot, Valérie Briois, Christine Surcin, Mathieu Morcrette, Valérie Buissette, Thierry Le Mercier, Sophie Cassaignon, David Portehault
An aqueous synthetic route at 95 °C is developed to reach selectively three scarcely reported vanadium oxyhydroxides. Häggite V2O3(OH)2, Duttonite VO(OH)2, and Gain's hydrate V2O4(H2O)2 are obtained as nanowires, nanorods, and nanoribbons, with sizes 1 order of magnitude smaller than previously reported. X-ray absorption spectroscopy provides evidence that vanadium in these phases is V(+IV). Combined with FTIR, XRD, and electron microscopy, it yields the first insights into formation mechanisms, especially for Häggite and Gain's hydrate...
October 12, 2016: Inorganic Chemistry
Serge Ayissi, Krisztián Palotás, Hanna Qin, Lijuan Yang, Paul A Charpentier
Rutile-monoclinic phase transitions of vanadium oxide (VO2) nanocrystals adsorbed on graphene-based substrates are of current scientific interest, although their adsorption and growth mechanisms have not been investigated theoretically. In this study, we use density functional theory (DFT) calculations for determining the binding energies and predicting the corresponding directions of growth of VO2 nanostructures (rutile and M1-monoclinic) interacting with both pure graphene and functionalized graphene nanoribbons...
October 12, 2016: Physical Chemistry Chemical Physics: PCCP
Alessandro Chieregato, Claudia Bandinelli, Patricia Concepción, M Dolores Soriano, Francesco Puzzo, Francesco Basile, Fabrizio Cavani, José M López Nieto
The design of suitable catalysts for the one-pot conversion of glycerol into acrylic acid (AA) is a complex matter, as only fine-tuning of the redox and acid properties makes it possible to obtain significant yields of AA. However, fundamental understanding behind the catalytic phenomenon is still unclear. Structure-reactivity correlations are clearly behind these results, and acid sites are involved in the dehydration of glycerol into acrolein with vanadium as the main (or only) redox element. For the first time, we propose an in-depth study to shed light on the molecular-level relations behind the overall catalytic results shown by several types of V-containing catalysts...
October 12, 2016: ChemSusChem
Yuan Liu, Guijian Liu, Qinyuan Qu, Cuicui Qi, Ruoyu Sun, Houqi Liu
Vanadium in coals may have potential environmental and economic impacts. However, comprehensive knowledge of the geochemistry of V in coals is lacking. In this study, abundances, distribution and modes of occurrence of V are reviewed by compiling >2900 reported Chinese coal samples. With coal reserves in individual provinces as the weighting factors, V in Chinese coals is estimated to have an average abundance of 35.81 μg/g. Large variation of V concentration is observed in Chinese coals of different regions, coal-forming periods, and maturation ranks...
October 11, 2016: Environmental Geochemistry and Health
Esra Mutlu, Tim Cristy, Steven W Graves, Michelle J Hooth, Suramya Waidyanatha
Tetravalent (V(IV)) and pentavalent (V(V)) forms of vanadium were selected for testing by the National Toxicology Program via drinking water exposure due to potential human exposure. To aid in the test article selection, drinking water formulations (125-2000 mg/L) of vanadyl sulfate (V(IV)), sodium orthovanadate, and sodium metavanadate (V(V)) were characterized by ultraviolet/visible (UV/VIS) spectroscopy, mass spectrometry (MS), or (51)V nuclear magnetic resonance (NMR) spectroscopy. Aqueous formulations of orthovanadate, metavanadate, and vanadyl sulfate in general were basic, neutral, and acidic, respectively...
October 10, 2016: Environmental Science and Pollution Research International
Mannar R Maurya, Bithika Sarkar, Fernando Avecilla, Isabel Correia
The ONO donor ligands obtained from the condensation of 4-benzoyl-3-methyl-1-phenyl-2-pyrazoline-5-one (Hbp) with benzoylhydrazide (H2bp-bhz I), furoylhydrazide (H2bp-fah II), nicotinoylhydrazide (H2bp-nah III) and isonicotinoylhydrazide (H2bp-inh IV), upon treatment with [V(IV)O(acac)2], lead to the formation of [V(IV)O(bp-bhz)(H2O)] 1, [V(IV)O(bp-fah)(H2O)] 2, [V(IV)O(bp-nah)(H2O)] 3 and [V(IV)O(bp-inh)(H2O)] 4, respectively. At neutral pH the in situ generated aqueous K[H2V(V)O4] reacts with ligands I and II, forming potassium salts, K(H2O)2[V(V)O2(bp-bhz)] 5 and K(H2O)2[V(V)O2(bp-fah)] 6, while ligands III and IV give neutral complexes, [V(V)O2(Hbp-nah)] 9 and [V(V)O2(Hbp-inh)] 10, respectively...
October 10, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
David McNulty, Quentin Ramasse, Colm O'Dwyer
The majority of electrode materials in batteries and related electrochemical energy storage devices are fashioned into slurries via the addition of a conductive additive and a binder. However, aggregation of smaller diameter nanoparticles in current generation electrode compositions can result in non-homogeneous active materials. Inconsistent slurry formulation may lead to inconsistent electrical conductivity throughout the material, local variations in electrochemical response, and the overall cell performance...
September 15, 2016: Nanoscale
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