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Diclofenac (DCF) is a type of micropollutant from pharmaceutical waste which brings adverse effect to the aquatic environment if the wastewater is not well-treated. The impregnation of biopolymer on activated carbon has recently gained increasing attention to improve the removal efficiency of micropollutant from wastewater. Magnetite rice husk activated carbon/chitosan composite (MACCS) with high adsorption capacity was developed in this study by modifying rice husk activated carbon (RHAC) with iron oxide (Fe3O4) nanoparticles and cross-linked with chitosan. The adsorption performance of the synthesized MACCS was compared with rice husk activated carbon (RHAC) and magnetite chitosan (MCS) for DCF removal from aqueous solution. The physical and chemical properties of the synthesized biosorbents were investigated via scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). MACCS was identified as the best performing biosorbent and its DCF removal ability was further tested in batch with different parameters. The parameters reported in this study were solution pH and the synthesis ratio of activated carbon and chitosan. The most effective adsorption of DCF with MACCS was achieved at solution pH of 2.5 and activated carbon to chitosan ratio of 1:2. In acidic condition, the perfect coating of chitosan which contained abundance of amine group attached on the RHAC with high porosity had achieved 94% removal of DCF with maximum adsorption capacity of 270 mg/g. Besides, the MACCS could easily be separated from the aqueous solution due to its magnetic property. From the results, the MACCS biosorbent showed its potential to be an excellent alternative adsorbent for the removal of micropollutant from wastewater.

In this study, sugarcane bagasse (SCB) as a cheap and effective biosorbent was used for copper ions (Cu(II)) removal and modification was performed on SCB with HCl chemical washing and mercerization with strong NaOH in order to improve the removal capability of Cu(II) from aqueous solution. The effects of three influencing parameters including pH, temperature and initial metal ion concentration on Cu(II) adsorption were investigated for both untreated and modified SCB samples (U-SCB, HCl-SCB and M-SCB). The maximum removal efficiency obtained in the experiments was 98.75% for HCl-SCB while M-SCB was 93.1% at pH 5 with an initial metal ion concentration of 10 mg L−1. Four isotherm models including Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm were used to describe the adsorption process of Cu(II) ions for each SCB sample. Among these four isotherms, the experimental data was best fitted to Langmuir isotherm with R2 above 0.95. Based on the Langmuir isotherm, the maximum monolayer adsorption capacity was 0.523, 2.006 and 0.938 for U-SCB, HCl-SCB and M-SCB. It was concluded that the modification performed on SCB with HCl was able to improve the removal efficiency of Cu(II) from 71.6% up to 98.75%.

Gasochromic switchable mirrors based on magnesium--nickel alloy thin films capped with catalytic Pd-Ag alloy thin films were prepared by a DC magnetron sputtering method. The dependence of the hydrogenation/dehydrogenation process of the films on hydrogen concentration and the ingredient of the catalytic layer has been investigated using different concentration of hydrogen gas for gasochromic optical switching cycles. The hydrogenation/dehydrogenation switching durability shows strong dependence on those two factors. We quantitatively measured the effect of different factors on the durability, response time and optical transmittance of the film, and then used characterization to find out the reason for the prolonged life and utilize this fact to improve the switching cycle of the gasochromic smart window.

We propose a novel ghost imaging scheme which is especially served to a pure phase object A spatially incoherent beam is mixed with a coherent beam of the same frequency field by a beamsplitter. Then we perform the ghost imaging scheme using the mixed beam. Our theoretical result shows that this approach is capable of reconstructing a pure phase object in joint-intensity measurement. The visibility of the images is also analysed for two pure phase objects, an optical wedge and a phase grating.

We study theoretically the transmission coefficients and the spin-tunneling time in ferromagnetic/semiconductor/ferromagnetic three-terminal heterojunction in the presence of Rashba spin-orbit interaction, in which one-dimensional quantum waveguide theory is developed and applied. Based on the group velocity concept and the particle current conservation principle, we calculate the spin-tunneling time as the function of the intensity of Rashba spin-orbit coupling and the length of the semiconductor. We find that as the length of the semiconductor increases, the spin-tunneling time does not increase linearly but shows behavior of slight oscillation. Furthermore, with the increasing of the spin-orbit coupling, the spin-tunneling time increases.

The performance of a micro propulsion system is determined primarily by the performance of the micro nozzles. A rectangular cross-section convergent–divergent micro nozzle, with a throat width of 20 µm and an expansion area ratio of 1.7, is fabricated and studied using experiment and numerical simulation. Experiments are conducted to measure the mass flow rates and pressure distributions near the nozzle's throat under various outlet pressures. The results of the numerical simulations accord with the experimental data. Moreover, differences between the micro scale flow and the conventional scale flow are discovered from the simulation results. The Mach number near the downstream position of the micro nozzle's throat is lower than that in the conventional nozzle. In the divergent region of the micro nozzle, there is a supersonic area instead of the shock wave that usually occurs in the conventional scale nozzles. The results of the numerical simulation also show that the position of the sonic point moves away from the throat towards the outlet with the decrease in the size of the nozzle. This particular behavior is attributed to the higher viscous dissipation in micro nozzles as compared to that in the conventional scale nozzles.

In the presence of an electric field perpendicular to the axes of the wire, the binding energy of shallow donor impurity in finite square quantum well wires is calculated. For different impurity positions and aspect ratios of the wires, we investigate the Stark shift of the 1s-like state energy of the impurity by expanding the wavefunction into a two-dimensional Fourier series and by using the variational scheme. It is found that the electric field breaks down the degeneracy of the states for impurities symmetrically positioned within the structure and leads to red-shift or blue-shift of the impurity Stark energy, respectively. Furthermore, the scaling rule of the binding energy will not be valid for the square quantum well wire under the applied electric field.

The binding energies of the ground state of excitons in the GaAs/Ga1−xAlxAs square quantum-well wire in the presence of a magnetic field are investigated by using the variational method. It is assumed that the magnetic field is applied parallel to the axis of the wire. The calculations of the binding energy as a function of the wire size have been performed for infinite and finite confinement potentials. The contribution of the magnetic field makes the binding energy larger obviously, particularly for the wide wire, and the magnetic field is much more pronounced for the binding energy in a square quantum wire than that in a cylindrical quantum wire. The mismatch of effective masses between the well and the barrier is also considered in the calculation.

Experiments have been conducted to investigate nitrogen gas flow characteristics through four trapezoidal silicon microchannels with different hydraulic diameters. The volume flow rate and pressure ratio are measured in the experiments. It is found that the friction coefficient is no longer a constant, which is different from the conventional theory. The characteristics are first explained by the theoretical analysis. A simplified rectangular model (rectangular straight channel model) is then proposed. The experimental results are compared with the theoretical predictions based on the simplified rectangular model and the two-dimensional flow between the parallel-plate model which was usually used. The difference between the experimental data and the theoretical predictions is found in the high-pressure ratio cases. The influence of the gas compressibility effect based on the Boltzmann gas kinetic analysis method is studied to interpret the discrepancy. We discuss two important factors affecting the application extent of different prediction models.

Employing the Green's function method, we investigate the Josephson current through a quantum dot side coupled to a topological superconducting nanowire sustaining a pair of Majorana zero modes. It is found that the Josephson current is blocked when the quantum dot is side coupled to a superconducting nanowire in a topologically trivial phase. However, when the topological superconducting nanowire transitions from a topologically trivial to a topologically non-trivial phase, an Andreev bound state arises at the zero Fermi energy of the quantum dot due to leakage of the Majorana zero mode. Thus a Josephson current can be induced by leakage of the Majorana zero mode into the quantum dot. The Josephson current shows a plateau-like structure and a clear-cut trivial/non-trivial phase transition, as a function of a Zeeman field imposed on the system. The transition and plateau-like structure can be used to probe the existence of the Majorana zero mode. The current-phase relation has also been studied.

A wafer-level testable silicon-on-insulator-based microring modulator is demonstrated with high modulation speed, to which the grating couplers are integrated as the fiber-to-chip interfaces. Cost-efficient fabrications are realized with the help of optical structure and etching depth designs. Grating couplers and waveguides are patterned and etched together with the same slab thickness. Finally we obtain a 3-dB coupling bandwidth of about 60nm and 10 Gb/s nonreturn-to-zero modulation by wafer-level optical and electrical measurements.