Photopyroelectric Spectroscopic Studies of ZnO-MnO2-Co3O4-V2O5 Ceramics

Photopyroelectric (PPE) spectroscopy is a nondestructive tool that is used to study the optical properties of the ceramics (ZnO + 0.4MnO2 + 0.4Co3O4 + xV2O5), x = 0–1 mol%. Wavelength of incident light, modulated at 10 Hz, was in the range of 300–800 nm. PPE spectrum with reference to the doping level and sintering temperature is discussed. Optical energy band-gap (Eg) was 2.11 eV for 0.3 mol% V2O5 at a sintering temperature of 1025 °C as determined from the plot (ρhυ)2 versus hυ. With a further increase in V2O5, the value of Eg was found to be 2.59 eV. Steepness factor ‘σA’ and ‘σB’, which characterize the slope of exponential optical absorption, is discussed with reference to the variation of Eg. XRD, SEM and EDAX are also used for characterization of the ceramic. For this ceramic, the maximum relative density and grain size was observed to be 91.8% and 9.5 μm, respectively

Study on adsorption behavior of alkaline protease on poly(ether sulfone) integrated with fish scale hydroxyapatite as self organized in ion exchange membrane

This study was performed to investigate the physiochemical effect on the protease adsorption produced by Bacillus sp. using highly specific ion exchange membrane (IExM). Effects of pH solution (adjusted with HCl and NaOH), ionic strength (adjusted by NaCl), and initial concentration on adsorption study were performed by using affinity polyethersulfone (PES) membrane integrated with fish scale hydroxyapatite (FSHAp), FSHAp/PES IExM. At 1.0 M, the maximum adsorption capacity was recorded by 0.229 mg/cm2 in 90 minutes incubation time. The optimum pH was found to be at pH 8 with adsorption capacity of 0.211 mg/cm2 in 90 minutes incubation time. The optimum adsorption capacity with 0.204 mg/cm2 was observed when adsorption study performed with initial concentration at 0.9 mg/ml. Experimental data showed the protease adsorbed higher in alkaline condition compared to acidic solution. Further experiment showed that increase in ionic strength leads to noticeable increase in adsorption capacity which is due to aggregation of enzyme molecules in solution. The adsorption study also showed great adsorption behavior when high initial concentration applied as high number of free enzyme molecule to be adsorbed

The conductivity study of hybrid solar cells of TiO2 and doped with Bixa orellana for solar cells application

The application of nature dyes was explored for solar cells due to several advantages for green technology. These can be supporting in renewable energy alternatives, which must include solar energy. This system was fabricated as hybrid solar cells, which consist of organic and non-organic materials. Metal oxide semiconductor (MOS), TiO2, was selected as charge separation and transport. Bixa orellana used as extracted natural dyes solution in order to enhance the absorption of photons. The dyes were extracted by using immerging in methanol solution and left until dyes being extracted. The dyes were coated on ITO glass by using Electrochemical Impedance Spectroscopy (EIS) varied by 1, 3, 5, 7 and 10 layers of scan. This work focuses on conductivity and charge carrier study of thin film. The result shows the conductivity was increase due to several parameters that are, thickness of thin films, and intensity of light, mixture of natural dyes and concentration of dyes solution. The conductivity was then supported with the energy band gap via UV-Vis Spectroscopy

Photopyroelectric characteristics of Pr6O11 - ZnO ceramic composites.

Characteristics of different Pr6O11 ceramic composites were studied using photopyroelectric spectroscopy. The amount of Pr6O11 in the composite was varied from 0.1 to 0.75 mol% at the sintering temperature of 1190 and 1270°C. It was found that optical energy band-gap (Eg) of the composite is reduced by increasing the amount of Pr6O11 in the composite at both sintering temperatures. However, the decrease in Eg was relatively less at a sintering temperature of 1270°C as compared to that of 1190°C. XRD analysis showed that all samples have two phases, that is ZnO and intergranular layers composed of Pr6O11 and few small peaks of Pr2O3. EDAX results further showed that the Pr6O11 and Pr2O3 were segregated in the grain boundaries. Maximum grain size of 5.85 μm and relative density of 94.5% were found in these ceramics at x = 0.1 and 0.5 mol%, respectively, for 1270°C sintering temperature

Optical characterization on ITO/TiO2/P3HT/Areca Catechu/Au for thin film hybrid solar cell

In this research, dye sensitized solar cell is fabricated by a combination of inorganic titanium dioxide nanoparticles sensitized by a locally available natural dye extract from organic Areca Catechu nut. This hybrid solar cells are fabricated accordingly by deposition of ITO/TiO2/P3HT/Areca Catechu/Au by using electrochemical method. The deposition rates of TiO2 are varied from 0.05, 0.07, 0.09 to 0.11 vs-1 whereas the number of scan of each layers are fixed to 5. The absorption spectra analysis is carried out in the wavelength range 200 to 600 nm, showed a wide and significant absorption spectrum in UV and visible regions. Analysis shows that scan rate affects the electrical conductivity of hybrid solar cell. The highest conductivity is recorded at 0.278 Scm-1 corresponding to the scan rate of 0.07 Vs-1at a potential value of 3.5 V

Automated power control system for reactor TRIGA PUSPATI

Reactor TRIGA PUSPATI (RTP) Mark II type undergoes safe operation for more than 30 years and the only research reactor exists in Malaysia. The main safety feature of Instrumentation and Control (I&C) system design is such that any failure in the electronic, or its associated components, does not lead to an uncontrolled rate of reactivity. The existed controller using feedback approach to control the reactor power. This paper introduces proposed controllers such as Model Reference Adaptive Control (MRAC) and Proportional Integral Derivatives (PID) controller for the RTP simulation. In RTP, the most important considered parameter is the reactor power and act as nervous system. To design a controller for complex plant like RTP is quite difficult due to high cost and safety factors cause by the failure of the controller. Furthermore, to overcome these problems, a simulator can be used to replace functions the hardware and test could then be simulated using this simulator. In order to find the best controller, several controllers were proposed and the result will be analysed for study the performances of the controller. The output result will be used to find out the best RTP power controller using MATLAB/Simulink and gives result as close as the real RTP performances. Currently, the structures of RTP was design using MATLAB/Simulink tool that consist of fission chamber, controller, control rod position, height-to-worth of control rods and a RTP model. The controller will control the control rod position to make sure that the reactivity still under the limitation parameter. The results given from each controller will be analysed and validated through experiment data collected from RTP

Effect of Co3O4 doping and sintering temperature on optical energy band gap properties in Zn-Bi-Ti-O varistor ceramics

It is necessary to investigate the electronic states of ceramic based ZnO vasristor and effect of doped impurities at different concentration. Band gap (Eg) of the ceramic (99-x) mol% ZnO+0.5 mol% Bi2O3+0.5 mol% TiO2+ xCo3O4 where x = 0, 0.2, 0.4, 0.6 and 0.8 mol%, were determined using UV-Vis spectrophotometer. The samples were prepared via solid-state route and sintered at the sintering temperature at 1110, 1140 and 1170 °C for 45 and 90 min in open air. At no doping of Co3O4, the values of Eg are 2.991 ± 0.001, 2.989 ± 0.001 eV for 45 and 90 min sintering time; respectively. Eg was decreased to 2.368 ± 0.002 and 2.352 ± 0.001 eV at 0.8 mol% Co3O4 for 45 and 90 min sintering time; respectively. XRD analysis indicates that two main phases existed at all concentrations which are ZnO and secondary phases, Bi12TiO20, Zn2Ti3O8, ZnCo2O4 and Co3Ti3O. Relative density decreases with the addition of Co3O4 compared to that of undoped at all doping level. When Co3O4 is added in the ceramics, relative density increases with the increase of doping level at both 45 and 90 min sintering time. The variation of sintering temperatures and XRD findings of steepness factor are correlated with the UV-Vis spectrophotometer results of based ZnO varistor doped with Co3O4 due to the growth of interface states

Microstructural and nonlinear electrical properties of ZnO ceramics with small amount of MnO2 dopant

A small amount of MnO2 dopant was added to ZnO system to see the improvement of the ceramic varistor microstructural and nonlinear electrical properties. The samples were prepared using solid-state reaction method and the microstructure and nonlinear electrical properties of the ZnO-xMnO2 system were investigated for × = 0.011 to 0.026 mol%, at three sintering temperatures, 1180°C, 1240°C and 1300°C for 1 and 2 h sintering time. The XRD and EDAX analyses showed that the main phase was ZnO while ZnMnO3 and ZnMnO7 as the secondary phases developed and distributed at the grain boundaries and triple point junction. The SEM observation revealed that prolonged sintering temperature and time improved the microstructure uniformity and strongly influences the nonlinear behavior of the samples. The maximum density and grain size have been observed at 92% of theoretical density and 10.8 μm, respectively and occur at the highest sintering temperature which is 1300°C. The value of nonlinear coefficient α is found to increase with the increase of MnO2 doping level up to 0.016 mol% and drop with further doping level increment for all sintering temperatures and time

Preliminary characteristic of electrical non-linearity Co doped CMO-ZnO based varistor ceramic

Zinc oxide based varistor are widely used as circuit protective devices by literally absorbs these dangerous surge and spikes or grounding this unwanted magnitudes. In this research, zinc oxide is added with 20 mol% calcium manganite (CaMnO3) as an additive and Cobalt oxide (CoO) as doping material. Citrate-gel method is used as fabrication method compared to conventional solid-state method. This compound (ZnO-CaMnO3 -CoO) undergoes pre-sintering at 500 °C for 2 hours. In the sintering process, sintering temperature at 1300 °C, while the sintering time are setting at 1.5 hours. X-ray diffraction (XRD) patterns shows the components and phases of the compounds. The change of functional group was observed by Furrier transform infra-red (FTIR). I-V characteristic shows the value of nonlinear coefficient in the range of 1.0-2.0

Antibacterial property of Hylocereus polyrhizus and Hylocereus undatus peel extracts

Food-borne diseases have always been a major concern to the consumers, food safety authorities and food industries. Hylocereus spp or Pitaya peels are normally treated as wastes and will be discarded during processing. In this study, the antibacterial activity of ethanol, chloroform and hexane extracts from Hylocereus polyrhizus (red flesh pitaya) and Hylocereus undatus (white flesh pitaya) peels against nine pathogens was evaluated using disc diffusion method and broth micro-dilution method. Result from disc diffusion method showed that chloroform extracts from H. polyrhizus and H. undatus peel were found to exhibit good antibacterial activity where almost all the pathogens studied were successfully inhibited. Result of the minimum inhibitory concentration (MIC) showed that all extracts inhibit the growth of bacteria in the range of 1.25-10.00 mg/mL for all bacteria while their minimum bacteriacidal concentrations (MBC) indicated double of the MICs concentration except for B. cereus, L. monocytogenes and C. jejuni. Even though there is no clear trend indicating which bacteria were sensitive most to the extract, it can be concluded that chloroform extract of both H. polyrhizus and H. undatus peel showed the most potent antibacterial activity. Thus, these findings could be used further to understand the antibacterial property of the peel of pitaya fruits