Deposition of ZnO-Al (AZO) thin films for optical properties

Zinc Oxide (ZnO) is an inorganic compound and it is doped with aluminum to increase its capabilities. Aluminum Zinc Oxide (AZO) thin films are semiconductor materials that have band gap energy of 3.3eV. Various method of deposition have been study to growth AZO thin films. It has been extensively use in solar cell application, display application, gas sensing purposes, and thin film transistors (TFTs). In this work, sol gel method and spin coating was used to deposited AZO thin films. The ZnO sol-gel were synthesized using zinc acetate dihydrate as precursor, isopropanol as solvent, diethanolamine as sol stabilizer, and distilled water as oxidation agent. Then, synthesized ZnO were doped with different mole ratio of aluminum nitrate nanohydrate to produced AZO. The glass substrate was used as substrate and AZO thin films were then calcinated at 300°C and 500°C. The characterization of AZO thin film were done using X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Ultraviolet-visible spectroscopy (UV-Vis), Field Emission Scanning Electron Microscope (FESEM), and Energy Dispersive X-ray spectroscopy (EDX). The XRD results show that the ZnO with hexagonal wurtzite-type structure and temperature does have effect on the film intensity which related to crystallinity of thin films. Through AFM analysis, the value of RMS decreases from 3.018 nm to 2.240 nm as the temperature increases. Meanwhile, from UV-Vis result, it can be seen that AZO thin film have a high transmittance percentage above 90% after wavelength 400 nm with band gap value of 3.3 eV. FESEM image show that the grain boundary of AZO decrease with both parameter (mole ratio and calcinations temperature). Both parameters do have effect on AZO thin film. EDX analysis shows that there are existence of zinc, oxide, and aluminum

Cholic acid resistance and the adherence ability of Bifidobacterium pseudocaenulatum G4

The adherence capacity of Bifidobacterium longum BB536 and Bifidobacterium pseudocatenulatum G4 on HT-29 human epithelium cell line with the presence of cholic acid were assessed. B. longum BB536 showed a higher adhesion level on HT-29 human epithelium cell line compared to B. psudocatenulatumG4. However, in the presence of physiological concentration (0.094 and 0.94 ìM) of cholic acid, the adhesion level of Bifidobacterium strains dropped between 5 and 55% respectively, depending on pH, time and strain. The adaptation of Bifidobacterium strains to cholic acid was shown to be increasedwith time. It was concluded that the acquisition of cholic acid resistance by those Bifidobacterium strains promoted changes in the adhesion ability on HT-29 human epithelium cell line

Social learning approach in designing persuasive e-commerce recommender system model

Intention to purchase in existing online business practice is learned through observation of information display by online seller. The emergent growth of persuasive technologies currently holds a great potential in driving a positive influence towards consumer purchase behavior. But to date, there is still limited research on implementing persuasion concept into the recommender system context. Drawing upon the principle design of persuasive system, the main purpose of this study is to explore social learning advantages in creating persuasive features for E-Commerce recommender system. Based on Social Cognitive Theory, the influence of personal and environmental factors will be examined in measuring consumer purchase intention. In addition, dimensions of social learning environment are represented by observational learning theory and cognitive learning theory. From those reviews, this study assumed that social learning environment can be created based on attentiveness, retentiveness, motivational, knowledge awareness and interest evaluation cues of consumer learning factors. Furthermore, the persuasive environment of recommender system is assumed to have positive influence towards individual characteristics such as self-efficacy behavior, perceived task complexity and confused by over choice. Findings from those reviews have contributed to the development of a research model in visualizing social learning environment that can be used to develop a persuasive recommender system in E-Commerce and hence measures the impact towards consumer purchase intention

Development of visible light-responsive mono and codoped TiO2 for photocatalytic degradation of methyl orange dye

Titanium dioxide (TiO2) has been acknowledged as a promising photocatalyst in environmental remediation including wastewater treatment. In this study, TiO2 nanoparticles either by single or co-doped of iron (Fe) and nitrogen (N) via sol-gel method and calcined at 500 °C for 3 hours. This experiment investigated the performance of mono/co-dopant of TiO2 photocatalyst against methyl orange in aqueous solution under UV light irradiation. The experimental results showed the rate of degradation favored in co-doped TiO2 followed by mono doped TiO2 and pristine TiO2. The photocatalytic reaction followed pseudo first-order kinetics which were rationalized in terms of the Langmuir– Hinshelwood model and provided nearly complete degradatio

Estimation of Photovoltaic Module Parameters based on Total Error Minimization of I-V Characteristic

Mathematical Modelling of photovoltaic (PV) modules is important for simulation and performance analysis of PV system. Therefore, an accurate parameters estimation is necessary. Single-diode and two-diode model are widely used to model the PV system. However, it required to determine several parameters such as series and shunt resistances that not provided in datasheet.  The main goal of PV modelling technique is to obtain the accurate parameters to ensure the I-V characteristic is closed to the manufacturer datasheet. Previously, the maximum power error of calculated and datasheet value are considered as objective to be minimized for both models. This paper proposes the PV parameter estimation model based minimizing the total error of open circuit voltage (VOC), short circuit current (ISC) and maximum power (PMAX) where all these parameters are provided by the manufacturer. The performance of single-diode and two-diode models are tested on different type of PV modules using MATLAB. It found that the two-diode model obtained accurate parameters with smaller error compared to single-diode model. However, the simulation time is slightly higher than single-diode model due extra calculation required

Highly Sensitive Portable Liquid Petroleum Gas Leakage Detector

A simple, low cost and portable handheld liquid petroleum gas detector is reported in this paper. This battery powered handheld device is fitted with an MQ2 gas sensor and the output voltage of the sensor varies in accordance with the concentration of the gas in the surrounding. The sensor is connected to a microprocessor to display the output and produce an alarm when gas leakage is detected. The concentration of the gas present in the atmosphere is measured and displayed with a detection limit of 50 ppm. The sensor demonstrated high sensitivity towards gas leakages with the response and recovery times of 5 seconds and 8 seconds respectively

MLearning scaffolding model for undergraduate English language learning: bridging formal and informal learning

Learning using mobile devices also known as mLearning is the current buzz word in the present debates over the use of technology in education. Although mLearning has a high prospect for future education, it is yet to be incorporated widely in mainstream formal education. The lack of a contemporary theory of learning and model for the mobile era has been one of the main issues hindering the incorporation. Although past studies have discussed learning theories and models for mLearning at great length, there is a wide gap in the investigation of theory and model for language-learning in the mobile context. Hence, this paper aims to describe how learners could be assisted in language-learning via supportive scaffolding using mobile devices at the undergraduate level using Gilly Salmon’s five-stage scaffolding model. This model is supported by Vygotsky’s Zone of Proximal Development as the basis of learning theory. A case study was conducted on undergraduate language learning in a private university in an attempt to seek how this model could be applied for mLearning. The results from the study revealed improvement in learners’ language performance but more importantly the results also suggested some adaptations to be made to the model in order to adapt it to language-learning in the mobile context. As mLearning should include informal learning, the key characteristic of the adapted model shows how formal learning and informal learning can be interwoven using mLearning

Fabrication and characterization of modified ZnO- kapok fiber for separating surfactant-free oil-in-water emulsions

Natural sorbents have several benefits, including high sorption capacity, superior biodegradability, and low cost. Kapok is one of the natural fibers that can be used as absorbent material. These distinctive qualities give kapok fibers greater oil sorption capacity than other oil sorbents currently on the market. However, it is difficult to hold oil properly due to its waxy coating and smooth fiber surface. Thus, in this study, the rough surface fiber has been coated using ZnO via the hydrothermal method. Considering that ZnO is instinctually hydrophilic, this modification of the fiber compounds increases the adsorption of oil in fiber. The surface morphology interaction has been proven with an experiment using a scanning electron microscope (SEM) for morphology investigation, Fourier-transform infrared spectroscopy (FTIR) for identifying organic or inorganic materials, and physical interaction (contact angle analysis). The results obtained display a significant difference between modified kapok fiber with ZnO and raw kapok fiber. The FTIR analysis shows that the modified kapok exhibits the peak's level of intensity at 3268.88 cm-1 (stretching vibration peak of surface –OH decreases obviously as compared with that of raw kapok fiber, an absorption peak (symmetric stretching vibration of Zn–O–Zn) is observed at 652.28 cm-1. These results suggested that the whole sum of –OH was diminished, and hydrophobic ZnO nanoparticles were developed on the kapok fiber's surface. A surface morphology analysis using SEM shows that ZnO particles are present on the kapok fiber surface while comparing it to the raw kapok. Modified kapok shows a higher contact angle (138°) compared to raw kapok (125.5°). This can conclude that the kapok fiber modification was successfully achieved using the hydrothermal metho

Wear behavior of heat-treated coated carbon steel

A particular type of steel has a higher concentration of carbon than other types of steel called carbon steel. This study focused on the electrodeposition coating of Nickel Silicon Carbide (Ni-SiC) composite coating at 50 oC. In this study, medium carbon steel was used as a substrate. 25 g/l SiC was used during the deposition. The carbon steel was acted as the cathode and the carbon rod as an anode during electrodeposition. The coated sample was heat-treated at 350 OC for 1 hour. Scanning Electron Microscope (SEM) was used to analyze the surface morphology and microstructure of the coated and heat-treated sample before and after the wear test. The coated sample's element composition and phase distribution are determined using the Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD). To identify the hardness of the composite coating, Vickers micro-hardness test was used on the surface of the sample with 100g load in 10 seconds with ten indentations. Weight loss method was conducted to determine the average wear resistance of the sample. The wear behavior of the Ni-SiC was evaluated using the weight loss method with 3 g/l alumina as the abrasive material. The results showed that the heat-treated coating had higher wear resistance than the without heat treatment. The findings also showed that the sample with the heat-treatment process had a higher hardness. This proved that the heat-treated sample had the best wear behavior and hardness value compared to without heat treatment due to denser coating produce

Fabrication and characterization of modified ZnO-kapok fiber for separating surfactant-free oil-in-water emulsions

. Natural sorbents have several benefits, including high sorption capacity, superior biodegradability, and low cost. Kapok is one of the natural fibers that can be used as absorbent material. These distinctive qualities give kapok fibers greater oil sorption capacity than other oil sorbents currently on the market. However, it is difficult to hold oil properly due to its waxy coating and smooth fiber surface. Thus, in this study, the rough surface fiber has been coated using ZnO via the hydrothermal method. Considering that ZnO is instinctually hydrophilic, this modification of the fiber compounds increases the adsorption of oil in fiber. The surface morphology interaction has been proven with an experiment using a scanning electron microscope (SEM) for morphology investigation, Fourier-transform infrared spectroscopy (FTIR) for identifying organic or inorganic materials, and physical interaction (contact angle analysis). The results obtained display a significant difference between modified kapok fiber with ZnO and raw kapok fiber. The FTIR analysis shows that the modified kapok exhibits the peak's level of intensity at 3268.88 cm-1 (stretching vibration peak of surface –OH decreases obviously as compared with that of raw kapok fiber, an absorption peak (symmetric stretching vibration of Zn–O–Zn) is observed at 652.28 cm-1. These results suggested that the whole sum of –OH was diminished, and hydrophobic ZnO nanoparticles were developed on the kapok fiber's surface. A surface morphology analysis using SEM shows that ZnO particles are present on the kapok fiber surface while comparing it to the raw kapok. Modified kapok shows a higher contact angle (138°) compared to raw kapok (125.5°). This can conclude that the kapok fiber modification was successfully achieved using the hydrothermal metho