Synthesis of titanium dioxide nanoparticles via sucrose ester micelle-mediated hydrothermal processing route

Titanium dioxide nanoparticles were synthesized via low-temperature sucrose ester micelle-mediated hydrothermal processing route using titanium isopropoxide as the precursor. X-ray diffractometer revealed that the samples possessed a mixed crystalline phases consisting of anatase and brookite in which anatase was the main phase. Upon increasing the hydrothermal reaction temperature, the degree of crystallinity of the nanoparticles improved and their morphology transformed from bundles of needles to rods and to spheres. Photocatalytic behaviour of the as-synthesized nanoparticles was investigated by photodegradation of methylene blue solution in an ultraviolet A irradiating photoreactor. The as-synthesized nanoparticles exhibited higher photocatalytic performance as compared to the commercial counterpart

DFT + U and ab initio atomistic thermodynamics approache for mixed transitional metallic oxides: A case study of CoCu 2 O 3 surface terminations

This study develops a systematic density functional theory alongside on-site Coulomb interaction correction (DFT + U) and ab initio atomistic thermodynamics approachs for ternary (or mixed transitional metal oxides), expressed in three reservoirs. As a case study, among notable multiple metal oxides, synthesized CoCu2O3 exhibits favourable properties towards applications in solar, thermal and catalytic processes. This progressive contribution applies DFT + U and atomistic thermodynamic approaches to examine the structure and relative stability of CoCu2O3 surfaces. Twenty-five surfaces along the [001], [010], [100], [011], [101], [110] and [111] low-Miller-indices, with varying surface-termination configurations were selected in this study. The results portray satisfactory geometrical parameters for bulk CoCu2O3 and a band gap of 1.25 e V. Furthermore, we clarified the stoichiometrically balanced inverted (010)CoCuO, and the non-stoichiometric (001)CuOCu, (001)CoOCo, (110)OCoO and (110)CoOCu surface terminations as the most stable configurations, out of which, the (001)CuOCu shows the optimum stability in ambient conditions. The systematic approach applied in this study should prove instrumental for the analysis of other 3-element multicomponent systems. To the best of our knowledge, the present study is the first to report DFT + U analysis to any 3-multicompnent systems with two of them requires inclusion of U treatment (i.e., f- and d- orbitals) in the electronic structure calculations

Distribution and density of the partition function zeros for the diamond-decorated Ising model

Exact renormalization map of temperature between two successive decorated lattices is given, and the distribution of the partition function zeros in the complex temperature plane is obtained for any decoration-level. The rule governing the variation of the distribution pattern as the decoration-level changes is given. The densities of the zeros for the first two decoration-levels are calculated explicitly, and the qualitative features about the densities of higher decoration-levels are given by conjecture. The Julia set associated with the renormalization map is contained in the distribution of the zeros in the limit of infinite decoration level, and the formation of the Julia set in the course of increasing the decoration-level is given in terms of the variations of the zero density.Comment: 8 pages,8figure

Comparison of photocatalytic activity and cyclic voltammetry of zinc oxide and titanium dioxide nanoparticles toward degradation of methylene blue

We report on the photocatalytic degradation of methylene blue (MB) solution using commercial ZnO and TiO2 (P25) photocatalysts, in the form of slurry and immobilized on glass slides, under ultraviolet (UV) and solar irradiations. The average particle sizes of ZnO and P25 were 100 nm and 30 nm, respectively. Under both the irradiations, the photocatalytic activities of ZnO and P25 slurry resulted in better photocatalytic performance than the immobilized photocatalysts. Interestingly, ZnO showed better degradation capability in comparison to P25 under the solar irradiation. This result revealed that solar light provided a good source of energy to degrade MB in the presence of ZnO. The cyclic voltammetry analysis suggested that the photocatalysts possessed different mechanisms for the degradation of MB. The potential of immobilizing photocatalysts without compromising their performance may lead to easy handling of these materials, resulting in expanding their applications, for example, as a photoanode for photoelectrochemistry

Phenol dissociation on pristine and defective graphene

Phenol (C6H5O‒H) dissociation on both pristine and defective graphene sheets in terms of associated enthalpic requirements of the reaction channels was investigated. Here, we considered three common types of defective graphene, namely, Stone-Wales, monovacancy and divacancy configurations. Theoretical results demonstrate that, graphene with monovacancy creates C atoms with dangling bond (unpaired valence electron), which remains particularly useful for spontaneous dissociation of phenol into phenoxy (C6H5O) and hydrogen (H) atom. The reactions studied herein appear barrierless with reaction exothermicity as high as 2.2 eV. Our study offers fundamental insights into another potential application of defective graphene sheets

Extremely high arsenic removal capacity for mesoporous aluminium magnesium oxide composites

Mesoporous aluminium magnesium oxide composites with varying composition (Mg content: 0–100%) and high surface area (118–425 m2 g−1) are synthesized by a facile, low-cost and scalable sol–gel method. The mesostructure and crystallinity are controlled by varying the composition and calcination temperature. The mesopores evolve from hexagonally ordered to wormhole-like in structure with increasing Mg/Al ratio. The mesoporous aluminium magnesium oxide composites are highly efficient adsorbents for removing As(V) and As(III) from water. The mesoporous magnesium oxide shows unprecedentedly high adsorption capacities of 912 mg g−1 for As(V) at pH 3 and 813 mg g−1 for As(III) at pH 7 with a dose of 0.5 g L−1; significantly higher than those of reported adsorbents. Exceptional adsorption capacities for arsenic are retained over a wide pH range, and high selectivity for As(V) is realized even in the presence of co-existing anions. The arsenic adsorption performance correlates to the properties of the composites including the Mg/Al ratio, point of zero charge, crystallinity and mesostructure. The arsenic adsorption mechanism is elucidated. Due to their high surface areas, large pore volumes, tunable mesopore structures and high quantities of accessible hydroxyl groups with strong chemisorption binding affinity to arsenic, as well as extremely high adsorption capacities and selectivity, these mesoporous aluminium magnesium oxides are promising adsorbent candidates for the remediation of arsenic in water

Radiative Corrections to Double Dalitz Decays: Effects on Invariant Mass Distributions and Angular Correlations

We review the theory of meson decays to two lepton pairs, including the cases of identical as well as non-identical leptons, as well as CP-conserving and CP-violating couplings. A complete lowest-order calculation of QED radiative corrections to these decays is discussed, and comparisons of predicted rates and kinematic distributions between tree-level and one-loop-corrected calculations are presented for both pi-zero and K-zero decays.Comment: 25 pages, 18 figures, added figures and commentar

Enhanced photovoltaic performance using reduced graphene oxide assisted by triple-tail surfactant as an efficient and low-cost counter electrode for dye-sensitized solar cells

In this work, 4-bis(neopentyloxy)-3-(neopentyloxycarbonyl)-1,4-dioxobutane-2-silphonate (TC14) surfactant assisted reduced graphene oxide (rGO) was used as a counter electrode (CE) in dye-sensitized solar cell (DSSC). Field emission scanning electron microscopy and high-resolution transmission electron microscopy observations revealed that the TC14-rGO film was well dispersed on fluorine-doped tin oxide surface. The TC14-rGO modified CE based DSSC showed a power conversion efficiency of 0.828%, a short current density (JSC) of 2.72 mA cm−2, an open circuit voltage (VOC) of 0.65 V, and a fill factor (FF) of 41.9 which were higher than those CE fabricated from commercially available SDS surfactant assisted rGO. Results revealed that TC14-rGO is a potential CE material to construct efficient DSSC for future solar cell applications

Improving Risk Predictions by Preprocessing Imbalanced Credit Data

Imbalanced credit data sets refer to databases in which the class of defaulters is heavily under-represented in comparison to the class of non-defaulters. This is a very common situation in real-life credit scoring applications, but it has still received little attention. This paper investigates whether data resampling can be used to improve the performance of learners built from imbalanced credit data sets, and whether the effectiveness of resampling is related to the type of classifier. Experimental results demonstrate that learning with the resampled sets consistently outperforms the use of the original imbalanced credit data, independently of the classifier used

Secondary proton flux induced by cosmic ray interactions with the atmosphere

The atmospheric secondary proton flux is studied for altitudes extending from sea level up to the top of atmosphere by means of a 3-dimensional Monte-Carlo simulation procedure successfully used previously to account for flux measurements of protons, light nuclei, and electrons-positrons below the geomagnetic cutoff (satellite data), and of muons and antiprotons (balloon data). The calculated flux are compared with the experimental measurements from sea level uo to high float ballon altitudes. The agreement between data and simulation results are very good at all altitudes, including the lowest ones, where the calculations become extremely sensitive to the proton production cross section. The results are discussed in this context. The calculations are extended to the study of quasi trapped particles above the atmosphere to about 5 Earth radii, for prospective purpose.Comment: 7 pages, 5 figures, submitted to Phys. Rev.