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S López-Moreno, A H Romero, J Mejía-López, A Muñoz
In this work we report a complete structural and magnetic characterization of crystalline MnF2 under pressure obtained using first principle calculations. Density functional theory was used as the theoretical framework, within the generalized gradient approximation plus the Hubbard formalism (GGA+U) necessary to describe the strong correlations present in this material. The vibrational, the magnetic exchange couplings and the structural characterization of MnF2 in the rutile ground state structure and potential high pressure phases are reported...
November 29, 2016: Physical Chemistry Chemical Physics: PCCP
SeyedHosein Payandeh GharibDoust, Michael Heere, Magnus H Sørby, Morten B Ley, Dorthe B Ravnsbæk, Bjørn C Hauback, Radovan Černý, Torben R Jensen
Two new bimetallic sodium or potassium lanthanum borohydrides, NaLa(BH4)4 and K3La(BH4)6, are formed using La(BH4)3 free of metal halide by-products. NaLa(BH4)4 crystallizes in an orthorhombic crystal system with unit cell parameters, a = 6.7987(19), b = 17.311(5), c = 7.2653(19) Å and space group symmetry Pbcn. This compound has a new structure type built from brucite-like layers of octahedra (hcp packing of anions) with half of the octahedral sites empty leading to octahedral chains similar to rutile (straight chains) or α-PbO2 (zig-zag chains)...
November 17, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Nam Tran, Patrick Drogui, Satinder K Brar, Arnaud De Coninck
The synergistic effects were evaluated during the oxidation of carbamazepine using a sono-electrochemical process. The sono-electrochemical oxidation was performed using two types of experimental units (having 1L and 100L of working volume, respectively) and containing one anode (Ti/PbO2) and one cathode (Ti). Different operating parameters, including power of ultrasounds, current intensity and reaction time were investigated. The degree of synergy increased when the current intensity decreased, whereas it increased with the power of ultrasounds imposed...
January 2017: Ultrasonics Sonochemistry
Boutheina Gargouri, Olfa Dridi Gargouri, Ibtihel Khmakhem, Sonda Ammar, Ridha Abdelhèdi, Mohamed Bouaziz
Table olive processing wastewater (TOW) is a notoriously polluting due to its high organic and phenol content. To reduce them, an electrochemical process has been studied for the treatment of this effluent. Experiments were performed with a cell equipped with lead dioxide (PbO2) or boron-doped diamond (BDD) as anode and platinum as cathode, where Table Olive Wastewater (TOW) were destroyed by hydroxyl radicals formed at the anode surface from water oxidation. The comparative study of both systems shows the performance of the BDD anode compared to PbO2, explained by the large amounts of hydroxyl radicals generated effective at BDD anode and its synthesis characteristics...
January 2017: Chemosphere
Fengxian Ma, Yalong Jiao, Guoping Gao, Yuantong Gu, Ante Bilic, Stefano Sanvito, Aijun Du
By first-principle calculations, we have systematically studied the effect of strain/pressure on the electronic structure of rutile lead/stannic dioxide (PbO2/SnO2). We find that pressure/strain has a significant impact on the electronic structure of PbO2/SnO2. Not only can the band gap be substantially tuned by pressure/strain, but also a transition between a semiconductor and a gapless/band-inverted semimetal can be manipulated. Furthermore, the semimetallic state is robust under strain, indicating a bright perspective for electronics applications...
October 5, 2016: ACS Applied Materials & Interfaces
Chun-Wei Chiang, Ding-Quan Ng, Yi-Pin Lin, Pei-Jen Chen
Nanoscale lead dioxide (nPbO2(s)) is a corrosion product formed from the chlorination of lead-containing plumbing materials. This metal oxide nanoparticle (NP) plays a key role in determining lead pollution in drinking water and receiving water bodies. This study uses nPbO2(s) and medaka fish (Oryzias latipes) as surrogates to investigate the aqueous fate and toxicological risk of metal oxide NPs associated with water matrices. The larvae of medaka were treated with solutions containing nPbO2(s) or Pb(II)aq in different water matrices for 7-14 days to investigate the in vivo toxic effects of NPs...
October 4, 2016: Environmental Science & Technology
Lesley M Foley, Robert S B Clark, Alberto L Vazquez, T Kevin Hitchens, Henry Alexander, Chien Ho, Patrick M Kochanek, Mioara D Manole
BackgroundDisturbances in cerebral blood flow (CBF) and brain oxygenation (PbO2) are present early after pediatric cardiac arrest (CA). CBF-targeted therapies improved neurological outcome in our CA model. To assess the therapeutic window for CBF- and PbO2-targeted therapies, we propose to determine if CBF and PbO2 disturbances persist at 24 h after experimental pediatric CA.MethodsRegional CBF and PbO2 were measured at 24 h after asphyxial CA in immature rats (n=26, 6-8/group) using arterial spin label MRI and tissue electrodes, respectively...
September 16, 2016: Pediatric Research
Kallyni Irikura, Nerilso Bocchi, Romeu C Rocha-Filho, Sonia R Biaggio, Jesús Iniesta, Vicente Montiel
The statistical Response Surface Methodology (RSM) is applied to investigate the effect of different parameters (current density, j, NaCl concentration, [NaCl], pH, and temperature, θ) and their interactions on the electrochemical degradation of the Acid Green (AG) 28 dye using a Ti/β-PbO2 or Ti-Pt/β-PbO2 anode in a filter-press reactor. LC/MS is employed to identify intermediate compounds. For both anodes, the best experimental conditions are j = 50 mA cm(-2), [NaCl] = 1.5 g L(-1), pH = 5, and θ = 25 °C...
December 1, 2016: Journal of Environmental Management
Chong Wang, Yanxin Yu, Lifeng Yin, Junfeng Niu, Li-An Hou
Electrochemical degradation of ibuprofen (IBP) was performed on three types of Ti-based metal oxide electrodes. The degradation of IBP followed pseudo-first-order kinetics and the electrochemical degradation rate constant (k) over Ti/SnO2-Sb/Ce-PbO2 (9.4 × 10(-2) min(-1)) was 2.0 and 1.7 times of the values over Ti/Ce-PbO2 (4.7 × 10(-2) min(-1)) and Ti/SnO2-Sb (5.6 × 10(-2) min(-1)), respectively. The removal of total organic carbon and the energy consumption per order for IBP degradation were 93...
November 2016: Chemosphere
Atsuhiro Osuka, Daiki Shimizu, Seung-Kyu Lee, Dongho Kim
meso-Nitrosubporphyrinatoboron(III) was synthesized by nitration of meso-free subporphyrin with AgNO2/I2. Subsequent reduction with a combination of NaBH4 and Pd/C gave meso-aminosubporphyrinatoboron(III). meso-Nitro- and meso-amino-groups significantly influenced the electronic properties of subporphyrin, which has been confirmed by NMR and UV/vis spectra, electrochemical analysis, and DFT calculations. Oxidation of meso-aminosubporphyrinatoboron(III)s with PbO2 cleanly gave meso-to-meso azosubporphyrinatoboron(III)s that exhibited almost coplanar conformations and large electronic interaction through the azo-bridge...
August 16, 2016: Chemistry, An Asian Journal
Indu M Sasidharan Pillai, Ashok K Gupta
Application of a newly developed electrode material, PbO2 coated on mild steel plate (MS-PbO2), for the degradation of malachite green (MG) by photocatalytic oxidation (PCO), electrochemical oxidation (ECO) and photoelectrochemical oxidation (PEC) was explored. PEC performed marginally better at lower current density. However, the performances of PEC and ECO were equally good at higher current densities. One variable at a time optimization was carried out to identify the major parameters influencing ECO. Multivariate optimization was carried out with NaCl concentration, current density and pH as the variables and chemical oxygen demand (COD) removal efficiency and current efficiency (CE) as the responses...
November 9, 2016: Journal of Environmental Science and Health. Part A, Toxic/hazardous Substances & Environmental Engineering
Henrietta A Headlam, Peter A Lay
Evidence is growing that metabolites of Cr(III) dietary supplements are partially oxidized to carcinogenic Cr(VI) and Cr(V) in vivo. Hence, we examined oxidations of Cr(III) peptide (triglycine, tetraglycine and pentaglycine) complexes to Cr(VI) and Cr(V) by PbO2 at 37°C and physiological pH values between 3.85 and 7.4. The products were characterized by EPR and UV/Vis spectroscopies and electrospray mass spectrometry. At pH3.85, the monomeric Cr(V) complexes produced were relatively unstable and degraded over min to hr under the acidic conditions...
June 16, 2016: Journal of Inorganic Biochemistry
Carlos Eduardo O Andrade, André F Oliveira, Antônio A Neves, Maria Eliana L R Queiroz
EDTA is an important ligand used in many industrial products as well as in agriculture, where it is employed to assist in phytoextraction procedures and the absorption of nutrients by plants. Due to its intensive use and recalcitrance, it is now considered an emerging pollutant in water, so there is great interest in techniques suitable for its monitoring. This work proposes a method based on formation of the Mn(III)-EDTA complex after oxidation of the Mn(II)-EDTA complex by PbO2 immobilized on cyanoacrylate spheres...
November 5, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Gang Liu, Lingping Kong, Jinyuan Yan, Zhenxian Liu, Hengzhong Zhang, Pei Lei, Tao Xu, Ho-Kwang Mao, Bin Chen
We report an unprecedented surface doping-driven anomaly in the compression behaviors of nanocrystals demonstrating that the change of surface chemistry can lead to an interior bulk structure change in nanoparticles. In the synchrotron-based X-ray diffraction experiments, titania nanocrystals with low concentration yttrium dopants at the surface are found to be less compressible than undoped titania nanocrystals. More surprisingly, an unexpected TiO2(ii) phase (α-PbO2 type) is induced and obvious anisotropy is observed in the compression of yttrium-doped TiO2, in sharp contrast to the compression behavior of undoped TiO2...
June 9, 2016: Nanoscale
Guolong Huang, Jiachao Yao, Weilong Pan, Jiade Wang
Effluents after biochemical treatment contain pollutants that are mostly non-degradable. Based upon previous pilot-scale test results, an industrial-scale electro-oxidation device was built to decompose these refractory materials in the effluent from a park wastewater treatment plant. The electro-oxidation device comprised a ditch-shaped plunger flow electrolysis cell, with mesh-plate Ti/PbO2 electrodes as the anode and the same size mesh-plate Ti as the cathode. Wastewater flowed vertically through electrodes; the effective volume of the cell was 2...
September 2016: Environmental Science and Pollution Research International
Maria João Nunes, Nuno Monteiro, Maria José Pacheco, Ana Lopes, Lurdes Ciríaco
The behaviors of the electrodes Ti/PbO2 and Ti/Pt/PbO2 as anodes in the electro-oxidation of two antibiotics-tetracycline and oxytetracycline-were evaluated at different applied current densities, to evaluate the influence of the Pt interlayer. In the preparation of the electrodes, the electrodeposited β-PbO2 phase was homogeneous; no Ti or Pt peaks were detected in the diffractograms. The β-PbO2 surface presented significant roughness when deposited over the Pt interlayer, which also conferred significant conductivity to the material...
August 23, 2016: Journal of Environmental Science and Health. Part A, Toxic/hazardous Substances & Environmental Engineering
Felipe González-Cataldo, Sergio Davis, Gonzalo Gutiérrez
Ultrahigh-pressure phase boundary between solid and liquid SiO2 is still quite unclear. Here we present predictions of silica melting curve for the multimegabar pressure regime, as obtained from first principles molecular dynamics simulations. We calculate the melting temperatures from three high pressure phases of silica (pyrite-, cotunnite-, and Fe2P-type SiO2) at different pressures using the Z method. The computed melting curve is found to rise abruptly around 330 GPa, an increase not previously reported by any melting simulations...
2016: Scientific Reports
Annabel Fernandes, João Coelho, Lurdes Ciríaco, Maria José Pacheco, Ana Lopes
Boron-doped diamond (BDD) and Ti/Pt/PbO2 anodes were utilized to perform the electrodegradation of synthetic samples containing humic acid in the presence of different organic and inorganic carbon-containing and nitrogen-containing compounds. The influence of the chloride ion in the degradation process of the different synthetic samples was also assessed. The results showed that the anodic oxidation process can efficiently degrade recalcitrant compounds such as humic acid. The presence of carbonate in solution enhances the nitrogen removal, whereas it hinders the oxidation of the organic compounds...
May 20, 2016: Environmental Science and Pollution Research International
Masataka Umetani, Takayuki Tanaka, Taeyeon Kim, Dongho Kim, Atsuhiro Osuka
Double ring expansion from a 5,15-diarylporphyrin to a 5,16-diaryl-10,11,21,22-tetradehydro[20]porphyrin( occurred through a reaction sequence consisting of oxidation with PbO2 to 5,15-dioxoporphodimethene, a Corey-Fuchs reaction with tetrabromomethane in the presence of triphenylphosphine, and Fritsch-Buttenberg-Wiechell rearrangement triggered by tert-butyllithium. The obtained tetradehydro[20]porphyrin( and its mono- and dihydrogenated congeners exhibited 20 π antiaromatic character, whereas overhydrogenated congeners bearing a saturated bridge were nonaromatic owing to disrupted π conjugation...
July 4, 2016: Angewandte Chemie
Indu M Sasidharan Pillai, Ashok K Gupta
Anodic oxidation of industrial wastewater from a coke oven plant having cyanide including thiocyanate (280 mg L(-1)), chemical oxygen demand (COD - 1520 mg L(-1)) and phenol (900 mg L(-1)) was carried out using a novel PbO2 anode. From univariate optimization study, low NaCl concentration, acidic pH, high current density and temperature were found beneficial for the oxidation. Multivariate optimization was performed with cyanide including thiocyanate, COD and phenol removal efficiencies as a function of changes in initial pH, NaCl concentration and current density using Box-Behnken experimental design...
July 1, 2016: Journal of Environmental Management
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