This paper presents a novel preparation of copper (Cu) deposited titanium dioxide (TiO2) nanotubes in photoelectrochemical systems. The main target was improving TiO2 applications in the areas of energy conversion under visible light. Herein, we investigated different amount of Cu deposited TiO2 nanotubes using thermal evaporation technique. Based on the results, small amount of Cu (1.09 wt.%) showed the improvement in photoelectrochemical (PEC) response under visible light. Optimum amount of Cu deposited on TiO2 nanotubes will inhibit recombination rate of photogenerated charge carriers and improve the charge separation and transfer under visible light illumination. However, the excess amount of Cu deposited on TiO2 nanotubes will impede the photocurrent to flow and resulted in lower photoconversion efficiency. The reason may be attributed to the formation of composite structure on TiO2 nanotubes that serve as defects in the Cu/TiO2 interface by the lattice mismatch that will serve as recombination site for the charge carriers.

This paper presents a detailed investigation on the effect of heat-treatment process on the highly ordered titanium dioxide (TiO2) nanotube arrays in connection with the photoelectrochemical (PEC) response and hydrogen evolution rate. TiO2 nanotube arrays have been systematically heat-treated to control the transformation of as-anodized TiO2 amorphous structure to crystalline anatase and rutile phases. In this study, single crystalline TiO2 anatase phase exhibited a higher PEC response and hydrogen evolution rate at 400 °C heat treatment. The photocurrent density increase was mainly attributed to the effective transport of photo-induced electrons within the single crystal anatase phase. However, polycrystalline anatase and rutile phases showed the fluctuation in lower photocurrent density upon heat treatment above 500 °C. The mobility of photo-induced electrons was obviously hindered due to the recombination losses in defect sites between the anatase and rutile phase.

A model of heterogeneous, composite material is introduced, consisting of randomly distributed identical structural micro-domains endowed with electric charges or dipoles. Two cases are presented, one corresponding to a tightly packed (dense) material, another corresponding to highly-dispersed, small domains. The polarizability is computed in both cases, under the action of an external uniform electric field oscillating in time (a quasi-stationary field), and it is related to the displacement of the micro-domains from their positions of local equilibrium (translations or rotations). It is shown that the polarizability (or electric susceptibility) can exhibit characteristic (resonance) frequencies in the radio-frequency range and, even for moderate external fields, the material can undergo a displacive transition (similar to a ferroelectric transition), governed by non-linearities in the interaction energy of the micro-domains. The shift in the characteristic frequencies of the polarizability is estimated, as caused by the displacive modification.

The effect of heat treatment on phase transformation and crystalline microstructure properties of ternary Al-Cu-Zn alloys made under nonequilibrium conditions was investigated by means of differential scanning calorimetry spectrometry (DSC), optical microscopy observations and X-ray diffraction (XRD) patterns analyses. A set of ternary Al-X wt.% Cu-X wt.%Zn alloys with nominal compositions X = 2, 8, 20 and 25 were rapidly solidified under vacuum by high-frequency magnetic induction melting process. It was found that DSC heating at temperatures below 500 °C leads to phase transformation with the development of new phases which were identified by XRD patterns analyses such as the presence at ambient temperature of the rhomboedric structure τ′-Al4Cu3Zn phase in equilibrium with the expected tetragonal θ-CuAl2 in Al matrix. Measured DSC crystallization enthalpies of occurring phase transformation were given. Optical microscopy observations reveal refined grains and homogeneous surface textures of the as-melted Al-Cu-Zn alloys.

We report on the structural, spectroscopic and radiative emission characteristics of Eu-doped BaTiO3 (BT) nanosystem as compared to the pure BT system. The structural analysis was performed by X-ray diffraction (XRD) studies where the nanoscale BT sample exhibits a perovskite structure with most intense peak along (1 1 0) plane that depicts the preferred crystallographic orientation. Also, the diffraction peak intensity was found to be suppressed for Eu-doped BT nanosystem. The nature of radiative emission was evaluated via steady-state photoluminescence spectroscopy (PL) and positron annihilation spectroscopy (PAS). The improved radiative emission response, with Eu2+ doping, was believed to be accompanied by 4f65d→4f7 transitions in case of Eu-doped BT system. Whereas, PAS lifetime study of doped sample has revealed longer lifetimes indicating thereby partial substitution of Ti4+ by Eu2+ in BaTiO3 system.

The effect of argon concentration (10%–40%) on the surface properties of molybdenum is studied in nitrogen-argon mixture using 100 Hz pulsed dc glow discharge. The analysis is carried out by using X-ray diffractometer (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and Vickers microhardness tester to investigate surface properties of the nitrided samples. XRD results exhibit the formation of molybdenum nitrides. Crystallite size analysis and SEM morphology confirm the growth of nanostructured molybdenum nitride layers. Moreover, significant increase in surface hardness (by a factor of about two times) is found when the sample is treated for 30% argon in nitrogen-argon mixed plasma.

This paper studies the usage of earthed atomizing corona discharge to dispose waste water from oil extraction. The I-V characteristic curves of earthed atomizing positive and negative corona discharge are compared to study the influence of water flux and inter-electrode distance (which refers to the distance between line electrode and plate electrodes) on discharge characteristics, and to measure the turbidity, pH, biochemical oxygen demand (BOD5), chemical oxygen demand (COD) and the variation tendency of BOD5/COD in the process of dealing with waste water from oil extraction by earthed atomizing corona discharge. Ultimately, the mechanism of earthed atomizing corona discharge is analyzed. Research results indicate that when using earthed atomizing corona discharge to dispose of waste water from oil extraction, as the processing time grows there is a maximum value of turbidity, the pH level increases gradually then stabilizes, COD appears to descend, and BOD5 as well as BOD5/COD both have minimum values. When the processing time attains 300 min, waste water from oil extraction is suitable for biochemical treatment, foreshadowing that earthed atomizing corona discharge technology demonstrates energy conservation characteristic in improving the biodegradability of waste water from oil extraction and has a brilliant application prospect waiting ahead.

In this study, arrayed magnetic films were fabricated on the surface of 45# steel (magnetic). The magnetic field distribution of the micro-magnet arrayed surface was studied. Magnetically controlled suspension – ferrofluids was used as lubricant, which can be adsorbed by magnet. The tribological performance of the arrayed surface affected by the factors of micro-magnet, i.e., area ratio (r), thickness of each magnetic film (t) and magnetized or not, was evaluated using a pin-on-disk test rig. The results suggest that the specimen with 5% area ratio of arrayed magnet is the best of tried ones for low friction at the load-speed conditions. Compared with unmagnetized one, the arrayed surface after magnetizing mainly presents obvious anti-friction properties. The higher magnetic intensity of the surface is, the better anti-friction performance it shows at higher sliding speed condition (0.062–0.188 m/s).

The present paper proposes a new equation utilizing the nonlocal Euler-Bernoulli beam model to investigate the linear transverse vibration of an embedded single-walled carbon nanotube (SWCNT) which incorporates an extra-added nanoparticle. The elastic behavior of the surrounding medium is simulated by the Pasternak-type foundation model. Hamilton’s principle is applied to derive the governing equation, and the natural frequencies are obtained by the Galerkin method. The numerical results are compared with the molecular dynamics (MD) simulation as well as with the local continuum approach in the previous literature, to validate the nonlocal continuum elastic model. Unlike the classical continuum model, the present new approach shows acceptable accuracy and good agreement to the MD approximation. The results indicate that the fundamental frequencies are significantly dependent on the attached mass and boundary conditions. To study the effects of supported end conditions, three typical boundary conditions, namely clamped-clamped, clamped-pinned and pinned-pinned, are simulated. It is found that an attached mass causes a noticeable reduction in natural frequencies, in particular, for the clamped-clamped boundary condition, a stiff medium, stocky SWCNT and a small nonlocal parameter. In addition, when the position of the added nanoparticle is closer to the middle point of SWCNT length, the mass sensitivity is increased. Detailed results demonstrate that the present equation-based nonlocal continuum theory can be utilized for SWCNT-based mass sensor, efficiently.

3 d transition-metallic ions doped ZnS quantum dots (Q-dots) were synthesized by the facile wet-chemical process. During synthesis, various ions, i.e. manganese (Mn2+), cobalt (Co2+) and silver (Ag+), were used and their photoluminescence (PL) response investigated. UV-vis absorption studies show that the various dopant ions can effectively tune energy band structure. The PL emission band is red shifted on Mn2+ doping (~575 nm) as compared to pure ZnS Q-dots (~420 nm) which is due to 4T1(G) → 6A1(S) radiative transitions. Blue/green-emission peaks at ~487 nm/~508 nm observed, respectively, on Co2+/Ag+ doping are probably arising from the recombination between the sulfur vacancy level and the new dopant level. Luminescence emission efficiency (LEE) is found to be maximum at 5 mol% Mn2+ doping and then decreases. On doping by Ag+ the LEE is found to be maximum at 2 mol% doping and almost completely quenched at 5 mol% doping. Contrary to the above, Co2+ quenched the overall PL.

The propagation of a cylindrically polarized vectorial (CPV) beam through uniaxial crystals orthogonal to the optical axis is studied. Analytical formulae are derived for the field components of the beam upon the propagation. Intensity distributions and degrees of polarization of the beam after the propagation are revealed by numerical simulations, respectively. It is demonstrated that the beam profile no longer remains cylindrically symmetric all along the propagation due to the effect of anisotropy of the crystal. Furthermore, it is also shown that both the beam properties and anisotropy of the crystal can affect the evolution of CPV beam. These conclusions may provide specific knowledge of the propagation properties of CPV beam by the use of the crystal as a fundamental optical element.

New complex magnetic frustrated materials La2 − xErxTi2O7 (0 ≤ x ≤ 0.075) have been synthesized by solid-solid method. The crystallographic and magnetic properties were studied as a function of substitution of the La3+ ion by the Er3+ one. All samples are found to be single phase and crystallize in the monoclinic structure with P21 space group. Magnetic measurements have revealed the presence of dominant antiferromagnetic interactions and the absence of magnetic ordering until a temperature of 2 K. The magnetic study suggests that the Curie-Weiss temperature (θCW) is negative, as expected in the frustrated lanthanide sublattice in the Ln2 – xLn’xM2O7 structure. From the frustration index f = - θCW/TN, we have deduced the presence of a strong frustration phenomenon. The critical properties of the antiferromagnetic behavior, for x = 0.025, 0.05 and 0.075 samples, have been investigated. It was found that the 2D-self-avoiding walk (SAW) model is the best one to describe the critical phenomena.

A new approach for the nondestructive discrimination between genuine wild ginsengs and the counterfeit ones by near infrared spectroscopy (NIRS) was developed. Both discriminant analysis and back propagation artificial neural network (BP-ANN) were applied to the model establishment for discrimination. Optimal modeling wavelengths were determined based on the anomalous spectral information of counterfeit samples. Through principal component analysis (PCA) of various wild ginseng samples, genuine and counterfeit, the cumulative percentages of variance of the principal components were obtained, serving as a reference for principal component (PC) factor determination. Discriminant analysis achieved an identification ratio of 88.46%. With sample’ truth values as its outputs, a three-layer BP-ANN model was built, which yielded a higher discrimination accuracy of 100%. The overall results sufficiently demonstrate that NIRS combined with BP-ANN classification algorithm performs better on ginseng discrimination than discriminant analysis, and can be used as a rapid and nondestructive method for the detection of counterfeit wild ginsengs in food and pharmaceutical industry.

Electrical breakdown for low pressure argon gas and air, using copper thin films as the electrodes, was investigated. A specially designed cathode was built from copper thin film deposited on glass by a magnetron sputtering system creating the breakdown between those electrodes. The left side of Paschen’s curve and ionization coefficient η as well as the effective electron emission coefficient γ was obtained with respect to the variation of reduced electric fields for argon gas and air for different thin films thicknesses. It is concluded that reducing the thin film thickness as an electrode leads to a decrease of breakdown voltage and amplifying secondary electron emission. In addition, the influence of the gas type on dependence of breakdown characteristics on the electrode thickness was investigated.

The author presents the results of inelastic granular flow in an annular vibro-fluidized granular bed using hydrodynamic model suitable for dense inelastic granular gas. Using the steady-state balances of mass, momentum and energy for dissipative dense gas, the physics of the vibrated bed is initially validated in comparison with molecular dynamics (MD) simulations using the observable system parameters such as packing fraction and granular temperature. The instability of the vibrated bed is also explored due to the influence of additional dissipative inner wall. The phase map of inner and outer wall dissipations shows a characteristic line of division between the single roll systems with opposite rotations. In addition to single roll, a two roll system is observed as the density of the flow increases. The results show a qualitatively similar trend as seen in MD simulations for higher cell loadings. The findings are important as the results indicate that the increase in the packing fraction, in addition to side wall dissipation, leads to complex flow instabilities in the granular flow.

A new method has been applied for determining the mean square deviation of surface roughness and the imaginary part of permittivity of the material near-surface region. The method is based on the scattering and absorption of light in waveguide systems of integrated optics. It has high sensitivity and ease of implementation. The advantages of the proposed method are confirmed experimentally.

Regular arrays of vertically aligned microstructures consisting of entangled carbon nanotubes (CNTs) of different height and contact interface were grown on Si substrates with a bimetallic catalyst by water-assisted chemical vapor deposition. The arrays of high and wide CNT blocks (150–300 μm, 50–140 μm square) showed the ability to reach high stable field emission (FE) currents per block up to 300 μA due to the presence of multiple CNT emitters. However, significant outgrowth of the CNTs and limited mechanical stiffness of such blocks led to a limited FE homogeneity and alignment of the emitters. For the arrays of small rounded CNT bundles (∼5 μm, 20 μm diameter), well-aligned and highly efficient FE with maximum currents up to 40 μA per CNT bundle have been achieved. Unusual I-V curves with current saturation, strong activation effects and glowing spots just before destruction have been observed and are discussed by means of band structure considerations.

The electron transfer between diamond (0 0 1) surface without and with various vacancy defects and adlayer with various adsorbed atmospheric species is examined based on first-principles calculations, which plays an important role for the conductivity of diamond (0 0 1) surface. The results show that the electron transfer from the perfect diamond surface (without defect in diamond surface or subsurface layer) to the adlayer varies with the adlayer adsorbed on the surface. The largest electron transfer is about 1.08e from the perfect surface to the adlayer (10) (O2, H3O+) among the possible adlayers, such as (1) (H2O, H2O), (2) (H2O, H3O+), (3) (H2O, CO2) … (20) (N2, O2), (21) (N2, N2) layers. It is found that the vacancy defect in surface or subsurface layer also affects the diamond (0 0 1) surface conductivity by increasing or reducing the electron transfer from the surface to the adlayer. It is also noted that the electron transfer increases largely in the case that the (10) (O2, H3O+) system is adsorbed on the diamond (0 0 1) surface with vacancy defect in the surface or subsurface layer, in which the electron transfer is largest with 1.27e when the monovacancy defect forms in the subsurface layer. Our study is useful to understand the conductivity of diamond surface.