Bamboo charcoal was produced by pyrolysis or carbonization process with extraordinary properties such as high conductivity, large surface area and adsorption property. These properties can be improved by activation process that can be done thermally or chemically. In this paper, carbonization and activation process of bamboo, its structural and adsorption properties will be presented. Herein, the adsorption properties of bamboo charcoal that has fully utilized in solar cell as the electrode, adsorbent for water purification and electromagnetic wave absorber are reviewed.

The efficient reduction of graphene oxide (rGO) was performed using Sodium Borohydride (NaBH₄). These reduction approaches remove the majority of the oxygen-containing functional groups at the basal plane and surface of graphene oxide sheets. Structural and physiochemical properties of the GO were investigated with help of Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), and Ultraviolet-Visible-Near infrared (UV-Vis-NIR). The effects of the chemical reduction on a GO surface were analyzed using a Semiconductor Parameter Analyzer (SPA) in order to obtain the electrical resistance measurement. It was found that the resistance of reduced graphene oxide was greatly reduced when compared to the condition of before reduction process. Then, the formation of uniform thin film of rGO sheets was produced using vacuum filtration method in order to fabricate a gas sensor. In this project, plastic was used as a substrate. The sensor was then being exposed to NO₂ gas at room temperature in order to demonstrate the sensing ability of rGO.

An analytical model for depletion-mode MOSHEMTs for high-temperature applications is compared against the experimental GaN HEMT data of the AlGaN/GaN MOSHEMT for temperature dependence of 2DEG simulated at 75 °C and 125 °C. Both temperatures reduce the 2DEG density by 4 % in the GaN HEMT and 3 % in the AlGaN/GaN MOSHEMT. The cause of this diminishing effect is determined to be the decrease of the conduction band offset at high temperatures. Additionally, the device performance degrades at high temperatures due to the immature behaviour of GaN material when it operates at high-power dissipation with poor thermal conductivity. The simulated AlGaN/GaN MOSHEMT performance is comparatively improved compared to the experimental AlGaN/GaN HEMT devices. This improvement could be used to understand the nature of the 2DEG density vs the temperature, hence could enhance the experimental performance of the AlGaN/GaN MOSHEMT.

Nowadays, low power operational amplifiers (op-amp) are highly demand for most of the applications such as in medical and communication system. In this project, two stage op-amp is designed and operated at 1.8 V supply voltage. The supply voltage is scaled down to reduce the power dissipation of the op-amp. This is because the power will be high when there is a large supply voltage. The design is simulated and analysed using Mentor Graphic Pyxis software. This two stage op-amp is designed using the Silterra 0.13 µm process technology. The operational amplifier provides a Direct Current (DC) gain of 21.18 dB and a unity gain bandwidth of 6.31 MHz. The gain margin obtained from the op-amp is 14.07 dB and the phase margin of the op-amp is 94.26 ° for 3 pF compensation capacitor and 10 pF load capacitor. The result shows that circuit able to work at 1.8 V power supply voltage and the total power dissipation for the op-amp is 5.35 mW.

Purpose: This paper aims to analyze the negative impact of surface mount (SMT) pad and imperfect via structure such as stub, pad, non-functional pad (NFP) and anti-pad on the signal integrity at 40 Gbps transmission on printed circuit board (PCB) due to impedance mismatch or discontinuity. The optimized modeling of via and SMT structures is performed to achieve minimal impedance mismatch and insertion loss less than 10 dB for six-inch full path transmission line between transmitter and receiver on PCB at Nyquist frequency 20 GHz. Design/methodology/approach: This work is split into two phases. The first phase involves optimization of via and SMT structures in three-dimensional electromagnetic (3DEM) simulation using Hyperlynx Via Wizard and Keysight EMPro software, respectively, followed by analysis of time domain reflectometry (TDR) and insertion loss (Sdd21). Whereas, in the second phase, full path hybrid mode simulation involving vias for signal layer transition, a 6-inch PCB channel and SMT pads is performed using Keysight ADS software to observe the TDR, Sdd21 and eye diagram at 40 Gbps transmission. Findings: Imperfect via and SMT structures have a negative effect on signal reflection and attenuation. The optimized via and SMT minimizes the impedance mismatch by 81 per cent and insertion loss by 4.5 dB, ultimately enlarging the eye diagram opening to achieve minimal data loss at receiver with 40 Gbps transmission. Originality/value: The results of original empirical research work on signal integrity analysis that optimizes the PCB channel design to achieve 40 Gbps signal transmission are presented in this study. It serves as a reference guide for high-speed PCB layout design.