Abstract: This research presents a new perspective on optical biosensors based on zinc oxide nanoparticles. The widely known and successfully applied nanostructured material is modified by the dopant - the green phosphor Terbium, which embedded in the structure of zinc oxide and makes a significant contribution to the fluorescent response of the material in both the UV and visible spectral regions. The effect of various dopant concentrations on the fluorescence of nanostructures was studied; the nanostructures were examined by SEM.
Abstract: A serious of non-polar a-plane AlGaN-based multiple quantum wells (MQWs) were successfully grown on the semi-polar r-plane sapphire substrate with metal organic chemical vapor deposition technology. Intense MQWs-related emission peaks at an emission wavelength covered from 277-294 nm were observed based on the photoluminescence measurement. It was found that the employment of the trimethyl-aluminum (TMAl) flow duty-ratio modulation method which was developed based on the two-way pulsed-flows growth technique played a crucial role to control the Al composition of the non-polar a-plane AlGaN epi-layers. The non-polar a-plane AlGaN-based MQWs were deposited with the new developed TMAl flow duty-ratio modulation technique. Evident-3th order X-ray diffraction (XRD) satellite peak was observed from the high resolution-XRD measurement, proving the successful growth of non-polar a-plane AlGaN-based MQWs with abrupt hetero-interfaces.
Abstract: Multilayer low temperature co-fired ceramic (LTCC) is well known in usage as interconnect substrate, especially in high frequency application due to high electrical conductivity of the conductors and low loss of the LTCC dielectric. As substrate and packaging materials, there are many chips or devices placed on the multilayer LTCC board. In this paper, multilayer LTCC is implemented as the packaging at PIN photodiode (PD) module of the Radio over Fiber (RoF) system with the reason to increase thermal dissipation capacity of the PD module.
Abstract: Metal oxides are widely used as components in photovoltaic cells such as transparent conducting front electrodes or electron-transport layers, while only few metal oxides have been used as light absorbers. In this study, cuprous oxide was modified by anchoring TSCuPc dye molecules via potentiostatic electrodeposition approach. Fourier Transform Infrared Spectroscopy results display the different vibration peaks for S=O bond and C-N present in the TSCuPc modified Cu2O deposits signifying the attachment of TSCuPc on Cu2O. The highest absorbance peaks of Cu2O and TSCuPc at approximately 420 nm and 650 nm respectively was observed when 20uM of TSCuPc was added in the electrodeposition solution. Scanning Electron Microscopy reveals the formation of Cu2O film and formation of secondary submicron size structures with the addition of TSCuPc. The surface morphology of the secondary structures changes as the concentration TSCuPc increases. With the aforementioned results, it was verified that TSCuPc can be anchored to Cu2O via electrochemical route which could pave way in developing materials with high absorption in visible light applicable for optoelectronic devices.
Abstract: Graphene nanopore has been widely employed in nanofilter or nanopore devices due to its outstanding properties. The understanding of its mechanical properties at nanoscale is crucial for device improvement. In this work, the mechanical properties of graphene nanopore is thus investigated using atomistic finite element method (AFEM). Four graphene models with different pore shapes (circular (CR), horizontal rectangle (RH), and vertical rectangle (RV)) in sub-nm size which could be successfully fabricated experimentally have been studied here. The force normal to a pore surface is applied to mimic the impact force due to a fluid flow. Increasing pore size results in the reduction in its strength. Comparing among different pore shapes with comparable sizes, the order of pore strength is CR>RH>RV>SQ. In addition, we observe that the direction of pore alignment and geometries of pore edge also play a key role in mechanical strength of nanopores.
Abstract: In this work, the high strain rate compressive process of single crystal bulk copper was studied by molecular dynamics (MD) simulations. The simulated result indicated that the localized deformation caused the formation of shear bands (SBs). It was found that the formation of shear bands in single crystal was owing to a plenty of the plastic deformations that caused by dislocations slippage or twinning concentrated in a narrow region , and the temperature at the shear bands region was rising more quickly than the others.
Abstract: Ultrafine SnO2 is a new type of material, in the field of solar cells and semiconductors have a lot of use. To get different morphology and different properties of tin oxide powder material, making more applications in the field, the effect of the adjuvants on the properties of superfine SnO2 powders were distigated. Through the analysis of experimental results, the conclusions are shown the stronger the alkalinity of the auxiliary agent, the larger the grain size of the obtained particles and the more uniform the particles. When the molar ratio of salt to alkali is more than 1: 4, the amount of alkali is gradually reduced, the particle size is small, the morphology is not uniform and easy to agglomerate. When the molar ratio of salt to alkali is 1: 4, the smaller particle size is shown, the appearance morphology is uneven. The longer the reaction time, the more complete the grain, the more uniform the morphology. Under the condition of SnCl4 concentration of 0.05 mol/L, reaction time is 4 days, salt and alkali molar ratio is 1: 4, holding temperature is 200 °C, the auxiliary agent is NaOH, the size, shape and properties of synthesized SnO2 are the better.
Abstract: Natural rubber composite materials were prepared by using sulfur curing system of STR 5L added with hen eggshell and eggshell membrane to increase electrical and mechanical properties for biomimetic actuator and artificial muscle applications. Samples were vulcanized at temperature 150°C. Hen eggshells and eggshell membrane powder (0, 20, 40, and 60 phr) were added into natural rubber. The main composition of hen eggshells composed of 96.35 wt% calcium carbonate (CaCO3) while mostly composition of hen eggshell membrane is fibrous protein in terms of collagen. The best condition is addition of eggshell 40 phr (formula 3) and eggshell membrane 20 phr (formula 5) to obtain the highest storage modulus response equal to 2.85 x 106 and 2.97 x106 Pa, respectively. The curing time (Tc90) of pure natural rubber (formula 1), formula 3, and formula 5 are 8.22, 6.73, and 5.67 min, respectively. Furthermore, the curing time, rheology, and electrical field response of natural rubber composite materials were measured by moving die rheometer and impedance analyzer, and reported here.
Abstract: The aim of this study was to investigate the effect of replacing carbon black (CB) with inexpensive and environmentally friendly fillers – bentonite (BNT) and modified bentonite (M-BNT), on the curing properties of natural rubber (NR) composites. A control sample (unfilled NR) and thirteen NR composites filled with varied proportions of CB (x1), M-BNT (x2), and BNT (x3) based on a third degree – simplex lattice mixture design of experiment (DOE) were prepared in this study. Rheometric results showed that 33% substitution of CB with M-BNT provides the highest elastic torque values. Mixture of 10phr CB and 5phr M-BNT (CB/M-BNT/BNT 10/5/0) produces synergistic effect on curing. The presence of CB increases vulcanization rate due to its high basicity and low oxygen content while M-BNT serves as vulcanizing accelerator due to the present amine groups. Coefficients of reduced hierarchical models showed that the main factors contributed mainly on the curing parameters: β1 for the torque values, β2 for the scorch and curing time, and β3 for CRI. High values of coefficient of determination (r2) were computed particularly for MH (98.20%), ΔS (99.13%), ts2(95.68%), tc90(95.70%) and CRI (95.97%) establishing best fit between the model and experimental values.