Synthesis of mesoporous tungsten oxide nanofibers using the electrospinning method

Mesoporous tungsten oxide nanofibers were synthesized via a 500 °C thermal treatment of composite nanofibers prepared by electrospinning an ethanol solution consisting of tungsten ethoxide, P123 triblock copolymer, and polyvinylpyrrolidone. The as-electrospun composites exhibited unwoven nanofibers with an average diameter of 233 nm and a smooth surface morphology. During the calcination process, the composite nanofibers were shrunk to 85 nm in diameter and converted into rough, wormhole-like nanofibers. These were formed by agglomerating polycrystalline WO₃ particles of 10–30 nm along the axial direction. Furthermore, a measured pore-size distribution indicated that this nanofiber mat had different types of meso-sized porosities, which may have resulted from their wormhole-like structures and inter-fiber voids. In addition, it was observed to have the intra-grain porosity with the diameter of about 1.0 nm.     

Effect of aspect ratio on large deformation and necking of polyethylene

Objective of the study is to examine influence of aspect ratio of rectangular cross-section on the tri-axial stress state developed by necking in tensile specimens of polyethylene. The first part of the paper presents an experimental study that used two types of high-density polyethylene (HDPE) as sample material to identify the thickness-dependent relationship between engineering stress and elongation from tensile tests. The experimental study also shows that thinner specimens, i.e. higher aspect ratio, have lower neck propagation speed and higher flow stress, thus higher rate of energy consumption for the neck propagation. The second part of the paper presents finite element simulation of large deformation and necking in HDPE when subjected to uni-axial tension. True stress–strain relationship and governing equation for visco-plastic deformation are determined from the finite element simulation based on experimental data for the two HDPEs, which reveals influence of aspect ratio of cross-section on the stress state during the necking process. Results from the study indicate that plane-stress condition prevails when the aspect ratio increases, i.e. by decreasing the specimen thickness. The finite element simulation also supports the observation that necking in specimens with higher aspect ratio, i.e. thinner specimens, generates higher percentage of reduction in the thickness direction but lower in the width direction. The overall capability for the deformation endurance was found to improve by reducing the specimen thickness. The paper concludes that finite element simulation has successfully demonstrated the influence of aspect ratio of the cross-section on the stress state in the necking process. The paper also concludes that by combining experimental testing and finite element simulation, time-dependent deformation behaviour can be separated from the time-independent deformation behaviour, which is almost impossible to achieve based on the experimental techniques that rely purely on measurement only.     

Synthesis and magnetic property of FeMoO4 nanorods

Monoclinic FeMoO₄ nanorods have been prepared by the hydrothermal method in an acid aqueous solution. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectrum, X-ray photoelectron spectra and differential scanning calorimetry are used to characterize the structure, morphology and composition of the sample. The FeMoO₄ nanorods exhibit a ferromagnetic property at room temperature with the coercivity of 31.1 Oe and remnant magnetization of 4.09 × 10⁻³ emu/g, respectively. The magnetic mechanism has been discussed according to the calculated results of electron density of states for FeMoO₄ with consideration of oxygen vacancies by using the Vienna ab initio simulation package.     

Optimal depth estimation by combining focus measures using genetic programming

Three-dimensional (3D) shape reconstruction is a fundamental problem in machine vision applications. Shape From Focus (SFF) is one of the passive optical methods for 3D shape recovery that uses degree of focus as a cue to estimate 3D shape. In this approach, usually a single focus measure operator is applied to measure the focus quality of each pixel in the image sequence. However, the applicability of a single focus measure is limited to estimate accurately the depth map for diverse type of real objects. To address this problem, we develop Optimal Composite Depth (OCD) function through genetic programming (GP) for accurate depth estimation. The OCD function is constructed by optimally combining the primary information extracted using one/or more focus measures. The genetically developed composite function is then used to compute the optimal depth map of objects. The performance of the developed nonlinear function is investigated using both the synthetic and the real world image sequences. Experimental results demonstrate that the proposed estimator is more useful in computing accurate depth maps as compared to the existing SFF methods. Moreover, it is found that the heterogeneous function is more effective than homogeneous function.     

Mass-production of flexible and transparent Te-Au nylon SERS substrate with excellent mechanical stability

Nano Research - In the past two decades, the field of surface-enhanced Raman scattering (SERS) has flourished and many rational strategies have been reported for the successful construction of SERS...     

Hybrid CV-CC operation of capacitive deionization in comparison with constant current and constant voltage

Capacitive deionization (CDI) is a technique used to desalinate saline water by means of electrical potential applied to the electrode along both sides of a spacer channel through which water flows. CDI operates either at constant voltage (CV) or at constant current (CC) operation to desalinate saline water. The purity of the water is the main requirement at the outlet of the cell. The lowest effluent concentration is achieved within a very short time by operating the CDI cell at CV, but after that the effluent concentration continues to increase. On the other hand, in CC, the lowest concentration is achieved later as compared with CV, but once it is achieved it continues to remain constant until the target voltage is reached. In this paper, we combine both CV and CC operation to get the lowest concentration for maximum time during the adsorption process so that more desalinated water is produced. We compare hybrid CV-CC and constant voltage and constant current in terms of effluent concentration, energy consumption per ion removal, water recovery, and water quality by varying operational parameters like cell potential. It was observed that ultrapure water can be produced with hybrid CV-CC operation by systematically varying different process parameters like flow rate and cell potential to get better results.