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This study synthesized collagen-chitosan/PVA nanofiber composites using the electrospinning method. Characterizations included Fourier transform infrared spectroscopy (FTIR) and surface morphology using scanning electron microscopy (SEM). Investigations were carried out on tensile strength, degradation rate, and antibacterial test. It was found that the functional groups C–H, –OH, C–O, C–N, and N–H were suitable for PVA, collagen, and chitosan materials. The SEM showed that increasing the PVA composition caused a change in fiber diameter ranging from 34.64 to 71.63 nm. The tensile strength results show that the smallest nanofiber diameter has the highest ultimate strength value of 5.6 ± 0.4 MPa. In addition, it was found that the rate of degradation was directly proportional to the increase in concentration. Antibacterial activity test was carried out using two types of bacteria, namely gram-positive bacteria S. aureus and gram-negative bacteria E. coli. The results showed that the collagen-chitosan/PVA nanofiber composite had a diameter of antibacterial inhibition for E. coli and S. aureus bacteria, respectively.

The Zinc oxide is well known as a direct wide bandgap semiconductor material with many promising properties for blue/UV optoelectronics, transparent electronics, spintronic devices and sensor applications. Controllable bandgap tuning is important to widen its possible applications. In the present work, we applied density functional theory to study bandgap tuning of ZnO by introducing Na atom and Cl atom. Sodium acts as p-type doping, while chlorine acts as n-type doping for ZnO. The effect of Na and Cl doping in the study was calculated using the Density Functional Theory (DFT) method. The results indicate that ZnO, which is a natural n type semiconductor when doped with p type, has an increase in bandgap, on the contrary, doping with n type decreased its bandgap

This paper investigates the energy spectrum of a periodic one-dimensional Coulomb potential. The Schrödinger equation is solved numerically by our newly developed filter method (Phys. Rev E 96(3), 033302 (2017)). We observe that the energy spectrum can be obtained with a limited number of lattice. The results show the presence of an energy band structure as a function of lattice width and edge width. The comparison with the other potential model is also discussed.

Computational studies of silicene, which is a two-dimensional silicon material with honeycomb structure, has been carried out using Density Functional Theory Calculation. This study was aimed to determine the effects of doping gallium (Ga) atom and arsenic (As) atom on the magnetic properties of hydrogenated silicene. The results showed that pure silicene has very small magnetic properties, can be considered as non-magnetic. The process of hydrogenation on silicene changes it to become a magnetic material. The effects of Ga/As dopant on the magnetic properties of hydrogenated silicene depends on positions of Ga/As atom. Silicene with As atom at hollow site has the highest magnetic moment of 0.0592 μB . This value increases from the magnetic moment of hydrogenated silicene magnet by 104%.

Increasingly strict air pollution regulations along with global warming issue have peeked the interest in cleaner emission emitted by motor vehicle. In line with this, this study was aimed to develop a particulate filtering system based on an electrostatic principle for particulate matter with the diameter less than 2.5 μm, as known as a fine particle, and to test the performance of the filter. The filter consists of aluminum anodes and cathodes as the electrostatic electrodes. These electrodes were placed into the filter frame and installed on a motor vehicle muffler. The test was conducted to estimate the filter performance by measuring particle concentrations before and after using the filters. The filter was tested under four different electrostatic voltages:V1100 Volt,V2200 Volt,V3300 Volt, andV4400 Volt. The results show that the filter can reduce fine particle concentrations with the best efficiency of 50%, 60%, 62%, and 68%, respectively forV1,V2,V3, andV4. Filter performance was directly influenced by the applied voltage and the time of the test.

Materials with Mexican-hat electronic energy dispersions emerging from heterostructures, substrate effects, or spin–orbit couplings are believed to exhibit excellent thermoelectric properties due to its van Hove singularity of density of states in two-dimension. However, within a constant relaxation time approximation, we disprove this belief and we find that the singularity effect is cancelled down by the group velocity contribution in the thermoelectric transport distribution. Nevertheless, the band parameters can still be optimised to reach thermoelectric figure of merit larger than 2 in a wide bandwidth, thus keeping the potential of materials with Mexican-hat bands for thermoelectric applications.

Particulate matters with the diameter less than 2.5 µm or PM2.5, have been known to the health adverse. The developing of a measurement system of PM2.5 with a high precision has become a challenge in the last decade. We design the system using a NOVA SDS011 sensor to measure PM2.5 concentration. The problem is that the sensor has a capacity to measure particulate matter in the range of 0.3 to 10 µm, meanwhile we would like to design the measurement system of PM2.5 with the high precision. Another this that we address is how to optimize the sensor. A factor influenced the sensor optimization is a sample compartment. In this paper, we present the PM2.5 measurement system with the different compartments. The PM2.5 measurement system was calibrated using the 3443 Kanomax dust monitor. The result shows that the system works well with the compartment is important factor to increase the precision.

A low cost particulate matter measurement system has been designed to quantify the concentration in the air. The device has been built up by using a PM2.5 sensor. The sensor signal is processed and transfer to an Arduino UNO microcontroller. A long-range wireless communication is attached in the system for a distance measurement. The system has been validated using a 3522 Kanomax dust monitor model. The system was tested in the distance to characterize the performance. The system works properly to measure PM2.5 concentration. The PM2.5 concentration is presented in the average value of the 30 seconds sampling measurement. The system is controlled by using humidity and temperature sensor to avoid any damage caused by an environment condition. The maximum humidity and temperature for the system is restricted to 70% and 50°C respectively. The measurement system is accomplished to a NRF2401 radio module to allow to collect data remotely. In conclusion, the proposed system works well to measure PM2.5 in the environment. The system has an ability to measure particulate matter with maximum concentration of 750.0 μg/m3 with the resolution of 0.3 μg/m3.

Our recent developed filter method (Phys. Rev E 96(3), 033302, 2017) is applied here to investigate the energy spectrum and their corresponding wave function of one dimensional crystal. The periodic one dimensional potential is modelled by using one dimensional periodic harmonic oscillator, with variation on oscillator potential depth, quasi-potential depth, and crystal width. For energy less than the potential depth of the oscillator, the computational results reveal that the periodic harmonic oscillator produces a discrete spectrum, as the energy spectrum of a single harmonic potential. However, for energy almost equal to or greater than the depth of the potential oscillator, the periodic harmonic oscillator demonstrates the existence of pattern similar to energy band in crystal.

We have investigated the nonlinear susceptibility of atoms induced by high intensity, ultrashort laser pulses using a numerical solution of the time-dependent Schrodinger equation. We found that the instantaneous nonlinear susceptibility becomes saturated at high intensity. We also found that the saturation is closely linked to depletion of the ground state. Based on the numerical results, a simple model that generalizes the nonlinear susceptibility of atoms for high intensity, ultrashort laser pulses is proposed. We also investigated the ionization-induced dipole moment and found that the amplitude of the dipole moment induced by an ionized electron is, in general, smaller than that induced by a free-electron, and is attributable to a residual interaction between the ionized-electron and its parent ion.