208 research outputs found
THE EFFECTS OF TELEWORK ON ORGANISATION AND BUSINESS TRAVEL An exploratory study on a university context
In recent years, many companies have implemented telework to improve work efficiency and quality of life for employees. Transport planners attempt to assist companies in reducing business travel time losses related to traffic congestion by stimulating telework. However, current knowledge concerning the effects of teleworking on business travel is limited. Furthermore, despite constant promotion, telework penetration in The Netherlands remains low because companies are uncertain about the benefits of teleworking and its effects on their organisation and employees. In this paper, insights from literature review and pilot survey results are used to contribute to the development of a preliminary exploratory model.
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
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
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
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
Premelting of Thin Wires
Recent work has raised considerable interest on the nature of thin metallic
wires. We have investigated the melting behavior of thin cylindrical Pb wires
with the axis along a (110) direction, using molecular dynamics and a
well-tested many-body potential. We find that---in analogy with cluster
melting---the melting temperature of a wire with radius is lower
than that of a bulk solid, , by . Surface melting
effects, with formation of a thin skin of highly diffusive atoms at the wire
surface, is observed. The diffusivity is lower where the wire surface has a
flat, local (111) orientation, and higher at (110) and (100) rounded areas. The
possible relevance to recent results on non-rupturing thin necks between an STM
tip and a warm surface is addressed.Comment: 10 pages, 4 postscript figures are appended, RevTeX, SISSA Ref.
131/94/CM/S
Enhancement of thermal and mechanical stabilities of silicon doped titanium nitride coating by manipulation of sputtering conditions
This study investigates the influence of substrate (AISI M42 tool steel) bias voltage (from −30 to −80 V), on the mechanical properties of magnetron sputtered TiSiN coating derived from Ti and Si targets. Thermal stability, microstructure (crystallite size, microstrain, lattice constant), morphology and mechanical (hardness, Young's modulus, residual stresses) properties, of the deposited TiSiN coatings, were investigated with synchrotron powered X-ray diffraction (SR-XRD), X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and nanoindentation techniques. Rietveld analysis, of the in-situ SR-XRD, in the temperature range of 25–800 °C, demonstrated cubic TiN form in (Ti,Si)N solid solutions, with TiO2 and Ti2O3 identified at lower bias voltages. Density functional theory supplemented the experimental results.
Increase in the bias voltage resulted in: (i) a decrease in Si content, (ii) significant smoothening of surface morphology, (iii) change in the phase composition and microstructure, (iv) improved oxidation resistance and thermal oxidation threshold, and (v) hardness and Young's modulus of the coatings increased up to 50% to 33 GPa and 450 GPa, respectively
Solvothermal synthesis of SnO2/graphene nanocomposites for supercapacitor application
A facile solvent-based synthesis route based on the oxidation–reduction reaction between graphene oxide (GO) and SnCl2·2H2O has been developed to synthesize SnO2/graphene (SnO2/G) nanocomposites. The reduction of GO and the in situ formation of SnO2 nanoparticles were achieved in one step. Characterization by X-ray diffraction (XRD), ultraviolet-visible (UV–vis) absorption spectroscopy, Raman spectroscopy, and field emission scanning electron microscopy (FESEM) confirmed the feasibility of using the solvothermally treated reaction system to simultaneously reduce GO and form SnO2 nanoparticles with an average particle size of 10 nm. The electrochemical performance of SnO2/graphene showed an excellent specific capacitance of 363.3 F/g, which was five-fold higher than that of the as-synthesized graphene (68.4 F/g). The contributing factors were the synergistic effects of the excellent conductivity of graphene and the nanosized SnO2 particles
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High quality ZnO:Al transparent conducting oxide films synthesized by pulsed filtered cathodic arc deposition
Aluminum-doped zinc oxide, ZnO:Al or AZO, is a well-known n-type transparent conducting oxide with great potential in a number of applications currently dominated by indium tin oxide (ITO). In this study, the optical and electrical properties of AZO thin films deposited on glass and silicon by pulsed filtered cathodic arc deposition are systematically studied. In contrast to magnetron sputtering, this technique does not produce energetic negative ions, and therefore ion damage can be minimized. The quality of the AZO films strongly depends on the growth temperature while only marginal improvements are obtained with post-deposition annealing. The best films, grown at a temperature of about 200?C, have resistivities in the low to mid 10-4 Omega cm range with a transmittance better than 85percent in the visible part of the spectrum. It is remarkable that relatively good films of small thickness (60 nm) can be fabricated using this method
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