37 research outputs found

    Study of synthesis and characterization of bismuth oxyiodide thin film for non- toxic perovskite solar cells

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    Perovskite solar cells based on lead halide has demonstrated the fast increase in efficiency and advanced in photovoltaic technology in the last decade. However, perovskite solar cells that contain lead (Pb) has high efficiency but tangible risk to humans, animals, and the environment. Bismuth oxyiodide (BiOI) has been recognized as a suitable candidate of non-toxic material to replace lead without adversely impacting performance in perovskite solar cells. The interest in application of BiOI thin films is because BiOI has narrow band gap, high efficiency light absorption and high photo catalytic activity makes it the perfect contender to replace Pb as new non-toxic material perovskite solar cell. Thin films of BiOI were synthesized and deposited using Successive Ionic Layer Adsorption and Reaction (SILAR) on glass substrates. The same mole ratios of bismuth(III) nitrate pentahydrate (Bi(NO3).5H2O) and potassium iodide (KI) were diluted in deionized water to achieve clear solution. The microscope glass was dipped consecutively in 0.01M of (BiNO3)2.5H2O diluted in deionized water, 0.01M of (KI) diluted deionized water and in 50 ml deionized water. This process has been repeated for 30 times and finally the sample was dripped and dried in air. The sample was annealed at various annealing temperature from 250 °C, 350 °C, 450 °C, and 550 °C for 20 minutes. The optical properties and structural properties of BiOI thin films were characterized using X-ray powder diffraction (XRD), Ultraviolet-visible (UV-Vis) measurement and Field Emission Scanning Electron Microscope (FESEM). The Surface Profilometer (SP) was used to measure the thin films thickness. The structure of the films changed with the annealling temperature. The color of the film changes to the orange-yellow and become more yellowish with increasing annealing temperature. The morphology of FESEM images demonstrated that the BiOI thin films have flakes morphology structure with the size around 1μm. The deposited film thickness ranged between 3.479 μm and 8.082 μm. This study provided significant output and a pathway for non-toxic BiOI thin film for perovskite solar cells

    Back-to-back schottky diode from vacuum filtered and chemically reduced graphene oxide

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    This paper presents fabrication of reduced graphene oxide (rGO)/silicon (Si) back-to-back Schottky diode (BBSD) through graphene oxide (GO) thin film formation by vacuum filtration and chemical reduction of the film via ascorbic acid. In order to understand and assess the viability of these two processes, process condition and parameters were varied and analyzed. It was confirmed that the GO film thickness could be controlled by changing GO dispersion volume and concentration. Filtration of 200 ml of 0.4 ppm GO dispersion produced average film thickness of 53 nm. As for the reduction process, long duration was required to produce higher reduction degree. rGO film that underwent two times reduction at before and after transfer process with concentrated ascorbic acid gave the lowest sheet resistance of 3.58 MΩ/sq. In the final part of the paper, result of the BBSD device fabrication and current-voltage characterization were shown. The formed two rGO/Si Schottky junctions in the BBSD gave barrier height of 0.63 and 0.7 eV. The presented results confirmed the viability of fabricating rGO-based device using a simple method and without requirement of sophisticated equipment

    Inhibitory and resistance-modifying potential of plant-based alkaloids against methicillin-resistant staphylococcus aureus (MRSA)

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    Increased prevalence of methicillin-resistant Staphylococcus aureus (MRSA) has become a major threat to the health sector worldwide due to their virulence, limited therapeutic options and their distribution in both hospital and community settings. Discovery and development of new anti-MRSA agents as alternatives to the very few antibiotics left in the armamentarium are, thus, urgently required. Recently, an efflux mechanism in MRSA has been identified as one of the main contributors of resistance towards various structurally unrelated antibiotics. The potential of reserpine (a phytoalkaloid) as efflux pump inhibitor (EPI) against various microbes remains limited as the concentration needed for inhibition is toxic to humans. This study therefore aimed to evaluate 13 alkaloid compounds as potential inhibitory agents and/or potential EPIs against a panel of three MRSA isolates which not only differ in their susceptibility to vancomycin (amongst the last drugs available to treat serious MRSA infection), but also exhibited active efflux activity. Results indicated berberine's moderate inhibitiory activity against two MRSA isolates scoring a minimum inhibitory concentration (MIC) value of 125 microg/ml. Notable efflux inhibitory activity (ranging from two- to eightfold Ethidium Bromide MIC reduction) meanwhile was detected from quinine, piperine and harmaline using reserpine as the positive control. Findings from this study support the opinion that a vast number of potential phytocompounds with pharmacological potential await discovery. Therapeutic application of these compounds, however, warrants further investigation to ascertain their pharmacodynamics and safety aspects

    Evaluation of risk associated with treatment of fat, oil, and grease: Grease interceptor from food processing industry effluent using bowtie analysis

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    Fat, oil, and grease (FOG), a deposit in wastewater, develops from any processes in food and processing industries. FOG deposits in wastewater management systems can cause blockages in sewer systems. Grease Interceptor (GI) is one of the control measures to treat and prevent the blockage of FOG deposits in the sewer system. Nevertheless, few studies evaluate the extended hazard of GI application in FOG treatment. This study aims to assess the risk of GI in FOG treatment by using a bowtie technique. The hazard identified is FOG itself, whereas the top event was GI failure. The high contributions of the threats were an unsuitable variation of GI's type and design, no GI cleaning process schedule, and a clogged outflow pipe from GI. GI design according to standard and cleaning FOG deposits in GI by a licensed grease hauler were two suitable preventive barriers. The desludging process is essential to guarantee that the GI operates smoothly and is identified as an excellent recovery barrier. Inter-rater reliability (IRR) analysis to measure the consistency of their ratings on the data provided. The experts had a 75% overall agreement value of IRR risk rating value on assets, while 50% agreement value on people

    The role of big data analytics in digital health for COVID-19 prevention and control in Asia

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    Big data analytics (BDA) in digital health is critical for gaining the knowledge needed to make decisions, with Asia at the forefront of utilising this technology for the Coronavirus disease 2019 (COVID-19). This review aims to study how BDA was incorporated into digital health in managing the COVID-19 pandemic in six selected Asian countries, discuss its advantages and barriers and recommend measures to improve its adoption. A narrative review was conducted. Online databases were searched to identify all relevant literature on the roles of BDA in digital health for COVID-19 preventive and control measures. The findings showed that these countries had used BDA for contact tracing, quarantine compliance, outbreak prediction, supply rationing, movement control, information update, and symptom monitoring. Compared to conventional approaches, BDA in digital health plays a more efficient role in preventing and controlling COVID-19. It may inspire other countries to adopt this technology in managing the pandemic

    SOOT PARTICLE TRAJECTORIES OF A DI DIESEL ENGINE AT 18° ATDC CRANKSHAFT ANGLE

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    Among the major pollutants of diesel engine is soot. Soot is formed as an unwelcomed product in combustion system. Soot emission to the atmosphere leads to air global warming and health problem. Furthermore, deposition of soot particle on cylinder wall contaminates lubricant oil hence increases its viscosity. This reduces durability of lubricant oil, causing pumpability problems and increasing wear. Therefore, it is necessary to study soot formation and its movement in diesel engines. This study focuses on soot particle trajectories in diesel engine by considering diameter of soot particles that were formed at 18° ATDC crankshaft angle. These soot particle movement are under the influence of drag force with different radial, axial and angular settings and simulated by using MATLAB routine. Mathematical algorithm which was used in the MATLAB routine is trilinear interpolation and 4th order of Runge Kutta. Simulation was carried out for a combustion system of 4 valves DI diesel engine from inlet valve closing (IVC) to exhaust valve opening (EVO). The results show that small diameter of soot particles were transferred near the cylinder wall while bigger soot particle mostly moved in inner radius of the combustion chamber

    Persepsi guru terhadap pengaplikasian kemahiran berfikir aras tinggi (KBAT) dalam Reka Bentuk dan Teknologi (RBT) sekolah rendah

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    Reka Bentuk dan Teknologi (RBT) merupakan mata pelajaran baharu yang diperkenal dalam Kurikulum Standard Sekolah Rendah (KSSR) bertujuan untuk mengukuhkan kemahiran berfikir murid untuk menyediakan modal insan yang dapat bersaing pada peringkat global. Kurikulum RBT yang direka bentuk mampu menjadikan murid untuk menghasilkan produk yang kreatif dan berasaskan teknologi sekali gus menjadikan mata pelajaran ini wadah dalam mengaplikasikan kemahiran berfikir aras tinggi (KBAT). Pembentukan budaya KBAT bagi mata pelajaran RBT ini disandarkan sepenuhnya kepada pengetahuan isi kandungan dan kemahiran pedagogi guru serta kaedah pengaplikasian KBAT yang efektif semasa proses pengajaran dan pembelajaran dijalankan. Justeru, kajian rintis ini dilakukan untuk mengenal pasti tahap pengetahuan dan kemahiran pedagogi guru dalam mengaplikasikan KBAT kepada murid melalui mata pelajaran RBT. Seramai 36 orang guru di Daerah Kinta Utara, Perak yang mengajar mata pelajaran RBT terlibat dalam kajian ini. Hasil daripada kajian menunjukkan tahap pengetahuan isi kandungan guru RBT berada pada tahap sederhana (M = 2.558, SP = 0.379). Kemahiran pedagogi guru RBT pula berada pada tahap sederhana mahir (M = 2.625, SP =0.450), manakala penguasaan elemen kemahiran berfikir beraras tinggi dalam pengajaran dan pembelajaran RBT berada pada tahap sederhana (M = 2.754, SP = 0.444). Secara keseluruhannya kajian ini memberikan input bahawa para guru perlu memantapkan pengetahuan isi kandungan dan kemahiran pedagogi dalam kurikulum RBT bagi menerapkan KBAT semasa proses pengajaran dan pembelajaran dalam bilik darjah. Malahan, dapatan juga boleh dijadikan landasan bagi mencari model pengajaran dan pembelajaran yang terbaik bagi mengamalkan budaya KBAT dalam kalangan murid dalam bilik darjah

    Penerapan kemahiran berfikir aras tinggi (KBAT) dalam Kurikulum Reka Bentuk dan Teknologi (RBT) sekolah rendah

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    Kemahiran Berfikir Aras Tinggi (KBAT) yang diterapkan dalam kurikulum pendidikan negara menjadi aspirasi kepada pembentukan generasi yang mampu bersaing dan berjaya di peringkat global. Penekanan KBAT ini dikukuhkan dengan memperkenalkan mata pelajaran Reka Bentuk dan Teknologi (RBT) dalam Kurikulum Standard Sekolah Rendah (KSSR). Mata pelajaran RBT di ajar pada Tahap II di sekolah rendah sebagai satu usaha membangunkan modal insan abad ke-21 sekali gus menjayakan aspirasi tersebut. Sebagai pelaksana kepada kurikulum yang telah dibentuk, keberhasilan dalam menjayakan aspirasi ini bergantung penuh kepada keupayaan guru dan kemahiran guru. Namun begitu, guru-guru di sekolah masih mengamalkan kaedah konvensional dalam proses pengajaran dan pembelajaran malahan keupayaan untuk menerapkan KBAT juga masih rendah. Justeru, kertas konsep ini bertujuan untuk membincangkan kesediaan guru, masalah dan keperluan guru dalam melaksanakan pengajaran mata pelajaran RBT melalui integrasi KBAT di peringkat sekolah rendah. Guru perlu melengkapkan diri dengan pengetahuan dan kemahiran pedagogi KBAT dalam usaha untuk meningkatkan KBAT dalam kalangan murid. Pada masa ini, keperluan guru yang dikenal pasti ialah kursus pendedahan KBAT yang mengkhususkan kepada standard kandungan dan standard pembelajaran mata pelajaran RBT, penggunaan modul RBT, bahan maujud dan sumber bahan yang membantu pengajaran KBAT. Selain itu, sokongan dan perkembangan profesional yang berterusan dalam pengkhususan mata pelajaran RBT perlu diperkukuh agar guru-guru RBT dapat menguasai pengetahuan kandungan dan pedagogi dari segi teori dan praktikal yang dapat menjurus kepada penerapan KBAT di bilik darjah
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