78 results on '"Yew H"'
Search Results
2. How did the COVID-19 pandemic affect clinical training of Malaysian dental students: final year students' perspectives
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Yew, H. Z., primary, Dom, T. N. M., additional, Rani, H., additional, Chanthirasekar, N. A. L., additional, Yin, L. L., additional, Bukhari, M., additional, Xin, L. K., additional, Sabri, B. A. M., additional, Rosdy, N. M. M. N. M., additional, Esa, R., additional, Kacharaju, K. R., additional, Andiesta, N. S., additional, and Parolia, A., additional
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- 2021
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3. A laboratory investigation of colour changes in two contemporary resin composites on exposure to spices
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Yew, H Z, Berekally, T L, and Richards, L C
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- 2013
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4. Computer-Assisted Porcelain Laminate Veneer Preparation: A Scoping Review of Stereolithographic Template Design and Fabrication Workflows
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Xin Guan, Yew Hin Beh, and In Meei Tew
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dental esthetic ,tooth reduction ,CAD/CAM ,veneers ,Dentistry ,RK1-715 - Abstract
Computer-assisted preparation of porcelain laminate veneers (PLVs) using stereolithographic templates has been developed to enhance the accuracy of tooth preparation. However, the digital workflows involved in guided PLV preparation remain inconsistently defined across various practices. Therefore, this scoping review aimed to examine publications on computer-assisted PLV preparation to identify the key stage of digital workflows involved in designing and fabricating stereolithographic templates, as well as to highlight the limitations of various template designs. This scoping review aimed to identify publications on digital workflows for designing and fabricating stereolithographic templates in computer-assisted porcelain laminate veneer preparation. A systematic search on MEDLINE/PubMed, Web of Science and Scopus identified English-language articles published from 2014 to March 2024. Eligible articles focused on digitally designed and fabricated tooth reduction templates for porcelain laminate veneers, excluding conventional tooth preparation procedures for tooth reduction assessment. Seven clinical reports were included, demonstrating various 3D data acquisition techniques for virtual patient generation. All articles described virtual diagnostic wax-ups on digital casts, with two using a virtual articulator. Only five articles documented chair-side mock-ups with resin trial restorations to evaluate planned dental esthetics. Additionally, virtual tooth preparation prior to templates design was included in only four articles. The templates were designed using different software and ranged from simple designs with access windows to complex stacked templates with rotary instrument sleeved windows. Each template design had limitations affecting tooth reduction accuracy. All articles reported printing templates in clear acrylic resin using different technologies. In conclusion, the review highlights a lack of standardization in the digital workflow for designing stereolithographic templates for PLVs. Establishing a sound protocol for designing the tooth reduction templates is essential to ensure the accuracy and consistency of veneer preparation.
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- 2024
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5. Assessing intracellular pH regulation in H+-ATPase-rich ionocytes in zebrafish larvae using in vivo ratiometric imaging
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Yew, H. M., primary, Zimmer, A. M., additional, and Perry, S. F., additional
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- 2020
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6. Growth, sporulation and spore properties of Bacillus stearothermophilus produced in chemically defined media
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Lee, Yew H.
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579 ,Pharmacy - Abstract
The nutritional requirements for the vegetative growth of B. stearothermophilus strains NCIB 8919, NCTC lO,OO3 (wild) were found to be DL-methionine, biotin, nicotinic acid, thiamin, glucose and mineral salts. Strains NCIB 8920 required in addition L-tryptophan. B. stearothermophilus NCTC lO,OO3 (mutant) grew in a medium containing only glucose and mineral salts. Separate chemically defined media for the growth of Bacillus stearothermophilus strains NCIB 8919, 8920, NCTC lO,OO3 (wild) and NCTC lO,OO3 (mutant) were developed. Optimally aerated culture of B. stearothermonhilus NCTC lO,OO3(mutant) required 1.0 x 10-4 M. Mn2+ and 2.4 x 10-3 M. glutamic acid for optimal sporulation. Specific nutrient depletion of growth affected percentage sporulation. Spore suspensions of B. stearothermophilus NCTC 10,003 (mutant) were prepared from media in which sulphate (SO4-), nitrogen (N-),phosphate (Po4-), carbon (C-), magnesium-carbon simultaneously (Ng-C-) depleted growth. The heat resistance, dormancy and chemistry of these spores varied considerably. B. stearothermophilus NCTC 10,003 10,00310,00(mutant) spores prepared from carbon depleted cultures containing high and low concentrations of calcium, iron or manganese showed variations in heat resistance,dormancy and chemical composition. Progressive increase in the concentration of medium calciumfrom 1.0 X 10-5 M to 1.4 X 10-4 M. progressively increased theheat resistance of B. stearothermophilus NCTC 10,003 (mutant) spores prepared from nitrogen depleted cultures (N-). The thermodynamic functions for germination rate, magnesium and manganese release of N- and SO4- spores were within the range expected of enzymic reactions. The thermodynamic functions for the breaking of dormancy in SO4- spores and that for the release of D.P.A. were identical. Sublethal heating of SO4- spores (96.5°C and below) induced dormancy in these spores, whereas heating above 96.5°C gave rise to heat activation. Pooled results of the chemical analyses of all spore types studied showed that the concentration of D.P.A. and calcium were positively related to heat resistance whereas magnesium concentration and Mg/Ca molar ratio were inversely proportional to heat resistance.
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- 1976
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7. The Dependence of Boron Concentration in Diamond Electrode for Ciprofloxacin Electrochemical Sensor Application
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Ilmi Nur Indriani Savitri, Prastika Krisma Jiwanti, Ilmanda Zalzabhila Danistya Putri, Irkham Irkham, Yasuaki Einaga, Ganden Supriyanto, Yew Hoong Wong, Sachin Kumar Srivastava, and Che Azurahanim Che Abdullah
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boron-doped diamond ,ciprofloxacin ,human and health ,voltammetry ,Chemistry ,QD1-999 - Abstract
This study investigates the effects of boron concentration on boron-doped diamond (BDD) electrodes for electrochemical sensors of ciprofloxacin. The effects of boron concentration, scan rate, and pH of BDD electrodes with boron concentrations of 0.1, 0.5, and 1% were examined to determine the optimal conditions. Furthermore, square wave voltammetry (SWV) in phosphate buffer pH 7 was used to analyze the electrochemical behavior of ciprofloxacin. The results revealed a linear calibration curve in the concentration range of 30–100 μM with a recovery of 85–110%. Meanwhile, BDD electrode with the highest boron concentration in this experiment (1%) showed a very low limit of detection of 0.17 μM, meaning that 1% BDD gave a highly sensitive and significant measurement result for the electrochemical sensor of ciprofloxacin. With the results given, this study provides new insights for controlling boron concentrations in diamond electrodes for the electrochemical sensors of quinolone antibiotics.
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- 2023
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8. Computational, optical and feasibility studies of organic luminescence TMB-PPT blend for photovoltaic application
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Tejas Sharma, Thi Thu Ha Nguyen, Ngoc Ha Nguyen, Hoang Lan Ngo, Yew Hang Soo, Chai Yan Ng, and H.K. Jun
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Perovskite solar cell ,Long persistent luminescence ,After-glow effect ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
For enhanced applications of solar cells, organic luminescence materials like long persistent luminescence (LPL) present one of the promising avenues for light enhancement. Currently, most existing luminescent materials are based on an inorganic system that requires rare elements such as europium and dysprosium, with a very high processing temperature. Adopting organic luminescence materials that are free from rare elements is necessary, considering the low-temperature fabrication and low material cost. In this work, we investigate the optical properties of an organic luminescence blend consisting of 2,8-bis(diphenylphosphoryl)dibenzo [b,d]thiophene (PPT) and N,N,N′,N'-tetramethylbenzidine (TMB) through computational studies and experimental validations. Optical characteristics of the luminescence materials like optical absorption, photoluminescence, and time-resolved photoluminescence spectroscopy are characterized. To validate the functionality of the organic luminescence blend, the material is incorporated into the perovskite solar cell structure. Unfortunately, the blend is unable to emit sufficient illumination over extended periods due to its low intersystem crossing efficiency and weak spin-orbit coupling. Although the power conversion efficiency of the Luminescence/FTO/TiO2/Perovskite/Carbon structure is observed to be small under dark conditions, the application of organic luminescence materials can be further enhanced and explored.
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- 2024
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9. Fabrication and characterization of rGO-SnO2 nanocomposite for electrochemical sensor of ciprofloxacin
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Prastika Krisma Jiwanti, Dewi Kartika Azizah Sukardi, Anis Puspita Sari, Mai Tomisaki, Siti Wafiroh, Sri Hartati, Arramel, Yew Hoong Wong, Pei Meng Woi, and Joon Ching Juan
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Human & health ,Electrochemical sensor ,Ciprofloxacin ,rGO-SnO2 ,Screen printed electrode ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
The uncontrolled use of ciprofloxacin (CIP) has led to increased resistance in patients and potential health issues such as kidney disorders, digestive disorder, and liver complications. This study addresses these concerns by introducing an innovative electrochemical sensor utilizing a screen-printed electrode (SPE) enhanced with a novel rGO-SnO2 nanocomposite for the precise monitoring of CIP concentration. Through square wave voltammetry (SWV), this sensor demonstrates unparalleled sensitivity and accuracy in determining CIP levels. These analyses validated the superior performance of the SPE/rGO-SnO2 electrode, revealing CIP potential range of 0.85–1.50 V with irreversible oxidation reaction and an exceptional signal-to-background (S/B) ratio of 1.91, surpassing the 1.21 ratio achieved by the SPE/rGO electrode. The SPE/rGO-SnO2 electrode also exhibited the highest active surface area (0.0252 cm2), facilitating faster transfer electron. Crucially, the SPE/rGO-SnO2 electrode exhibited an impressively low limit of detection (LOD) at 2.03 μM within a concentration range of 30–100 μM for CIP, setting a new benchmark for sensitivity (9.348 μA/μM) in CIP detection. The %RSD value was less than 5 % indicating that this modified electrodes exhibit good precision and stability. The real-world applicability of this developed methods was exemplified through its successful implementation in the analysis of river water and milk, achieving remarkable recovery rates of 101.2 % and 97.7 %, respectively. Consequently, the SPE modified with rGO-SnO2 nanocomposite emerges as a highly promising and effective tool for precise and sensitive CIP measurement, offering unparalleled performance metrics and opening avenues for enhanced environmental and health monitoring.
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- 2024
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10. Rubidium zinc trioxide perovskite materials for photovoltaic solar cell applications: A first principle calculations
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Waqar Azeem, Muhammad Khuram Shahzad, and Yew Hoong Wong
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Perovskite materials ,Wide bandgap ,Electronic properties ,Elastic constants ,Photovoltaic solar cell ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
Perovskite materials are the well-known of solar cell applications and have excellent characteristics to study and explain the photocatalytic research. Exchange generalized gradient approximation (GGA) and Perdew-Burke-Ernzerhof-PBE correlation functionals and density functional theory (DFT)-based Cambridge Serial Total Energy Package (CASTEP) software are used to inspect the structural, electrical, mechanical, and the optical aspects of Zinc-based cubic perovskite RbZnO3. The compound is found to be in a stable cubic phase according to our study. The predicted elastic characteristics also satisfy the mechanical criterion for stability. Pugh's criterion indicates that RbZnO3 is brittle. The examination shows that the electronic band structure, RbZnO3 possesses an indirect bandgap (BG) that has 4.23eV. Findings of BG analysis agree with currently available evidence. Total and partial density of states (DOS) are used in the confirmation of degree of a localized electrons in special band. Optical transitions in compound are evaluated by adjusting damping ratio for the appropriate peaks of the notional dielectric functions. On one hand, the material is a semiconductor at absolute zero. On the other hand, the dielectric function's fictitious element dispersion illustrates the wide range of values for energy transparency. This substance might therefore be used in a solar cell to capture ultraviolet light.
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- 2024
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11. The load capacity of maxillary central incisor with simulated flared root canal restored with different fiber-reinforced composite post and cementation protocols
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Yew Hin Beh, Mohamad Syahrizal Halim, and Zaihan Ariffin
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Post and core technique ,Resin cements ,Scanning electron microscopies ,Fiber post ,Medicine ,Biology (General) ,QH301-705.5 - Abstract
Background This study aimed to evaluate the load capacity of maxillary central incisors with simulated flared root canal restored with different fiber-reinforced composite (FRC) post cemented with either self-adhesive or self-etch resin cement and its mode of fracture. Methods Sixty-five extracted maxillary incisors were decoronated, its canal was artificially flared and randomly categorized into group tFRC (tapered FRC post) (n = 22), mFRC (multi-FRC post) (n = 21), and DIS-FRC (direct individually shaped-FRC (DIS-FRC) post) (n = 22), which were further subdivided based on cementation resin. The posts were cemented and a standardized resin core was constructed. After thermocycling, the samples were loaded statically and the maximum load was recorded. Results The load capacity of the maxillary central incisor was influenced by the different FRC post system and not the resin cement (p = 0.289), and no significant interaction was found between them. Group mFRC (522.9N) yielded a significantly higher load capacity compared to DIS-FRC (421.1N). Overall, a 55% favorable fracture pattern was observed, and this was not statistically significant. Conclusion Within the limitation of the study, it can be concluded that prefabricated FRC posts outperform DIS-FRC posts in terms of the load capacity of a maxillary central incisor with a simulated flared root canal. The cementation methods whether a self-adhesive or self-etch resin cement, was not demonstrated to influence the load capacity of a maxillary central incisor with a flared root canal. There were no significant differences between the favorable and non-favorable fracture when FRC post systems were used to restored a maxillary central incisor with a flared root canal.
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- 2023
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12. Predictive analysis of the power spectral irradiance from blackbody radiation source using single pixel detector
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Hui Jing Lee, Pin Jern Ker, Mansur Mohammed Ali Gamel, Md Zaini Jamaludin, and Yew Hoong Wong
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Spectral irradiance ,Power densities ,Radiation temperature ,Energy ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
Accurate spectral irradiance measurement in the near-infrared range is significant for the design and characterization of photodetector and photovoltaic cells. Approximation method is commonly used to solve for the input power using estimated spectral irradiance, where the dependency on wavelength and temperature remains uncertain. This study aims to determine the power spectrum at different radiation temperatures using a single pixel photodetector, taking into consideration factors such as transmission spectra of alumina radiator, CaF2 collimating lens, responsivity, and measured photocurrent information of photodetectors. Utilizing predictive mathematical model, five commercial photodetectors, including Silicon, Germanium, In0.53Ga0.47As, In0.73Ga0.27As, and In0.83Ga0.17As were used to solve for the power densities as a function of wavelengths at radiation temperatures of 1000 °C and 1500 °C. The spectral irradiance of photodetectors was determined with a percentage difference of
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- 2023
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13. Al-Doped ZnO Thin Films with 80% Average Transmittance and 32 Ohms per Square Sheet Resistance: A Genuine Alternative to Commercial High-Performance Indium Tin Oxide
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Ivan Ricardo Cisneros-Contreras, Geraldine López-Ganem, Oswaldo Sánchez-Dena, Yew Hoong Wong, Ana Laura Pérez-Martínez, and Arturo Rodríguez-Gómez
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Al-doped ZnO ,alternative to commercial TCOs ,ultrasonic spray pyrolysis ,transparent devices ,figure of merit ,Physics ,QC1-999 - Abstract
In this study, a low-sophistication low-cost spray pyrolysis system built by undergraduate students is used to grow aluminum-doped zinc oxide thin films (ZnO:Al). The pyrolysis system was able to grow polycrystalline ZnO:Al with a hexagonal wurtzite structure preferentially oriented on the c-axis, corresponding to a hexagonal wurtzite structure, and exceptional reproducibility. The ZnO:Al films were studied as transparent conductive oxides (TCOs). Our best ZnO:Al TCO are found to exhibit an 80% average transmittance in the visible range of the electromagnetic spectrum, a sheet resistance of 32 Ω/□, and an optical bandgap of 3.38 eV. After an extensive optical and nanostructural characterization, we determined that the TCOs used are only 4% less efficient than the best ZnO:Al TCOs reported in the literature. This latter, without neglecting that literature-ZnO:Al TCOs, have been grown by sophisticated deposition techniques such as magnetron sputtering. Consequently, we estimate that our ZnO:Al TCOs can be considered an authentic alternative to high-performance aluminum-doped zinc oxide or indium tin oxide TCOs grown through more sophisticated equipment.
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- 2023
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14. Effects of volume fraction to the strength and ductility of a small-scaled fibre reinforced concrete beam
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Liong-Yew, H., primary, Sarbini, N. N., additional, Syahrizal, I. Izni, additional, Mohammad, I., additional, and Hasanah, A. S. L. Nor, additional
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- 2018
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15. Impact of ZnO nanoparticles as additive on performance and emission characteristics of a diesel engine fueled with waste plastic oil
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Ameer Suhel, Norwazan Abdul Rahim, Mohd Rosdzimin Abdul Rahman, Khairol Amali Bin Ahmad, Umrah Khan, Yew Heng Teoh, and Noh Zainal Abidin
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Waste plastic oil ,ZnO nanoparticles ,Diesel engine ,Emission ,Performance ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
Neat waste plastic oil (WPO) application as a fuel in engines reduces BTE and increases deleterious emissions of CO, UHC, NOx, and smoke due to the presence of insufficient oxygen and unbreakable hydrocarbon chains in WPO. Present investigation was performed to evaluate the impact of ZnO nanoparticles on the performance and emission characteristics of a diesel engine operated with the waste plastic oil (WPO20) blend. The objective of doping ZnO nanoparticles with WPO20 was to enhance the oxidation reaction and heat transfer rate between fuel droplets during combustion, which aids in completing the combustion. The sol-gel technique was adopted to successfully synthesize the ZnO nanoparticles using zinc acetate (Zn(CH3CO2)2.2H2O) and sodium hydroxide (NaOH) precursors. The structure and morphology of resulted particles were studied by XRD and FESEM tests. Both results indicate the stable formation of ZnO, and exhibit the crystallinity nature, spherical surface, and size consistency. The synthesized ZnO nanoparticles were infused in WPO20 blend in the amounts of 50, 100, and 150 ppm with the aid of the ultrasonication technique. Engine test was conducted with diesel fuel, WPO20 blend, and nano-infused fuels at a constant speed of 1500 rpm under various loads. The disparities in performance and emission characteristics were examined and compared with pure diesel fuel. The findings demonstrated that adding nanoparticles to WPO20 significantly lowers the smoke, CO, UHC, and NOx emissions and simultaneously improves the BTE and decreases the BSFC of the diesel engine. Optimum results were obtained for 100 ppm concentration of ZnO nanoparticles. Reduction of smoke by 11.86%, CO by 5.7%, UHC by 28%, and NOx by 14.93%, along with the enhancement of BTE by 2.47%, were noticed at maximum load with 100 ppm particles. Based on the test results, it is concluded that ZnO nanoparticles can be used as a suitable additive in WPO blends to improve the overall engine characteristics. Further scope of the present work is to study the effect of organic nanoparticles with WPO on engine behaviour, the detailed combustion of nanoparticles infused WPO, and the nanoparticles doped WPO on engine wear and corrosion.
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- 2023
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16. Adaptive network selection mechanism for telecardiology system in developing countries
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Yew, H. T., primary, Supriyanto, E., additional, Satria, M. H., additional, and Hau, Y. W., additional
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- 2016
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17. In-situ study of electrochemical migration of tin in the presence of bromide ion
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Ee Lynn Lee, A. S. M. A. Haseeb, Wan Jeffrey Basirun, Yew Hoong Wong, Mohd Faizul Mohd Sabri, and Boon Yew Low
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Medicine ,Science - Abstract
Abstract The miniaturization of electronic devices and the consequent decrease in the distance between conductive lines have increased the risk of short circuit failure due to electrochemical migration (ECM). The presence of ionic contaminants affects the ECM process. This work systematically investigates the ECM of tin (Sn) in the presence of bromide ions (Br−) in the range of 10−6 M to 1.0 M. Water drop test (WDT) was conducted in the two-probe semiconductor characterization system under an optical microscope as an in-situ observation. Polarization test was carried out to study the correlation between the corrosion properties of Sn and its ECM behaviour. The products of ECM were characterized by scanning electron microscope coupled with an energy dispersive X-rays spectrometer (SEM/EDX) and X-ray photoelectron spectrometer (XPS). The results confirm that the rate of anodic dissolution of Sn monotonously increases with the Br− concentration. However, the probability of ECM failure follows a normal distribution initially, but later increases with the Br− concentration. The main products of the ECM reactions are identified as Sn dendrites and tin hydroxide precipitates. The mechanisms of the ECM process of Sn in the presence of Br− are also suggested.
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- 2021
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18. Wind-roof calculator on internet (WIND-RCI) (Feel the wind on your laptop)
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Baskaran, B. A., Molleti, S., and Yew, H.
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Surcharges vent ,Wind loads - Abstract
This paper describes a web-based roof wind design calculator developed to improve the design of roofs by calculating wind loads. Named Wind-RCI (Wind-Roof Calculator on Internet), it calculates wind uplift design loads as a function of various parameters such as roof type, slope, wind speed, building height, roof area, building terrain, building type and openings. The web-based deign tool integrates several procedural steps and reduces the possibility of code language misinterpretations., The RCI 23rd International Convention & Trade Show: 28 February 2008, Phoenix, Arizona
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- 2008
19. Ternary Hybrid Materials for Highly Sensitive Acetone Sensing at Room Temperature
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Nurul Athirah Abu Hussein, Yew Hoong Wong, Zainal Arif Burhanudin, and Huzein Fahmi Hawari
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ternary hybrid materials ,room temperature ,VOC sensing ,acetone ,Crystallography ,QD901-999 - Abstract
The performance of a conventional metal oxide sensor (MOX) is highly dependent on its high operating temperature. Many researchers have tried to solve the problem by exploring hybrid materials. On the other hand, ternary hybrid materials have emerged as a promising class of materials with unique properties and potential applications in various fields, be it environmental or medical, such as in breath analyzers for prediabetes analysis. This article focuses on the synthesis method, characterization, and application of ternary hybrid materials for room-temperature sensors, as well as recent advances and future developments in the field. The materials consist of three different components, metal oxide (Fe3O4), polymer (polyaniline) and carbon-based materials (reduced graphene oxide), which were synthesized using in-situ methods. Five samples were prepared in different ratios. The properties of these materials were characterized using techniques such as X-ray diffraction (XRD), Raman, scanning electron microscope (SEM) and transmission electron microscopy (TEM). The XRD and Raman analyses showed the existence of all the individual constituents in the hybrid sample. SEM and TEM also showed a strong interaction between the constituent materials as a hybrid nanocomposite. The response and recovery time were studied against 1, 10 and 100 ppm acetone. The results show that the sample with 10 wt%Fe3O4-PANI-RGO (S2_10) has a reaction and recovery time < 32 s against the above ppm and has the highest sensing response at room temperature.
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- 2023
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20. Finger-Actuated Micropump of Constant Flow Rate without Backflow
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NurFarrahain Nadia Ahmad, Nik Nazri Nik Ghazali, Ahmad Taufiq Abdul Rani, Mohammad Hafiz Othman, Chia Ching Kee, Prastika Krisma Jiwanti, Arturo Rodríguez-Gómez, and Yew Hoong Wong
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microfluidic ,finger-actuated micropump ,Tesla vale ,flow rate ,diodicity ,Mechanical engineering and machinery ,TJ1-1570 - Abstract
This paper presents a finger-actuated micropump with a consistent flow rate and no backflow. The fluid dynamics in interstitial fluid (ISF) extraction microfluidics are studied through analytical, simulation, and experimental methods. Head losses, pressure drop, diodocity, hydrogel swelling, criteria for hydrogel absorption, and consistency flow rate are examined in order to access microfluidic performance. In terms of consistency, the experimental result revealed that after 20 s of duty cycles with full deformation on the flexible diaphragm, the output pressure became uniform and the flow rate remained at nearly constant levels of 2.2 μL/min. The flow rate discrepancy between the experimental and predicted flow rates is around 22%. In terms of diodicity, when the serpentine microchannel and hydrogel-assisted reservoir are added to the microfluidic system integration, the diodicity increases by 2% (Di = 1.48) and 34% (Di = 1.96), respectively, compared to when the Tesla integration (Di = 1.45) is used alone. A visual and experimentally weighted analysis finds no signs of backflow. These significant flow characteristics demonstrate their potential usage in many low-cost and portable microfluidic applications.
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- 2023
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21. Comprehensive computational target fishing approach to identify Xanthorrhizol putative targets
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Muhammad Shahid, Ahmad Azfaralariff, Douglas Law, Ahmed Abdulkareem Najm, Siti Aisyah Sanusi, Seng Joe Lim, Yew Hoong Cheah, and Shazrul Fazry
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Medicine ,Science - Abstract
Abstract Xanthorrhizol (XNT), is a bioactive compound found in Curcuma xanthorrhiza Roxb. This study aimed to determine the potential targets of the XNT via computational target fishing method. This compound obeyed Lipinski’s and Veber’s rules where it has a molecular weight (MW) of 218.37 gmol-1, TPSA of 20.23, rotatable bonds (RBN) of 4, hydrogen acceptor and donor ability is 1 respectively. Besides, it also has half-life (HL) values 3.5 h, drug-likeness (DL) value of 0.07, oral bioavailability (OB) of 32.10, and blood–brain barrier permeability (BBB) value of 1.64 indicating its potential as therapeutic drug. Further, 20 potential targets were screened out through PharmMapper and DRAR-CPI servers. Co-expression results derived from GeneMANIA revealed that these targets made connection with a total of 40 genes and have 744 different links. Four genes which were RXRA, RBP4, HSD11B1 and AKR1C1 showed remarkable co-expression and predominantly involved in steroid metabolic process. Furthermore, among these 20 genes, 13 highly expressed genes associated with xenobiotics by cytochrome P450, chemical carcinogenesis and steroid metabolic pathways were identified through gene ontology (GO) and KEGG pathway analysis. In conclusion, XNT is targeting multiple proteins and pathways which may be exploited to shape a network that exerts systematic pharmacological effects.
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- 2021
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22. Synergistic antidiabetic activity of Taraxacum officinale (L.) Weber ex F.H.Wigg and Momordica charantia L. polyherbal combination
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Nithiyaa Perumal, Meenakshii Nallappan, Shamarina Shohaimi, Nur Kartinee Kassim, Thiam Tsui Tee, and Yew Hoong Cheah
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Taraxacum officinale ,Momordica charantia ,Antidiabetes ,Dipeptidyl peptidase-4 (DPP-4) ,STZ-NA induced rat diabetic model ,LCMS ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Type 2 Diabetes Mellitus accounts for 90% of most diabetes cases. Many commercial drugs used to treat this disease come with adverse side effects and eventually fail to restore glucose homeostasis. Therefore, an effective, economical and safe antidiabetic remedy from dietary source is considered. Taraxacum officinale (L.) Weber ex F.H.Wigg and Momordica charantia L. were chosen since both are used for centuries as traditional medicine to treat various ailments and diseases. In this study, the antidiabetic properties of a polyherbal combination of T. officinale and M. charantia ethanol extracts are evaluated. The bioactive solvent extracts of the samples selected from in vitro antidiabetic assays; α-amylase, α-glucosidase, and dipeptidyl peptidase-4 (DPP-4) inhibition, and glucose-uptake in L6 muscle cells were combined (1:1) to form the polyherbal combination. The antidiabetic efficacy of polyherbal combination was evaluated employing the above stated in vitro antidiabetic assays and in vivo oral glucose tolerance test and streptozotocin-nicotinamide (STZ-NA) induced diabetic rat model. A quadrupole time-of-flight liquid chromatography-mass spectrometry (Q-TOF LCMS) analysis was done to identify active compounds. The polyherbal combination exerted improved antidiabetic properties; increased DPP-4, α-amylase, and α-glucosidase inhibition. The polyherbal combination tested in vivo on diabetic rats showed optimum blood glucose-lowering activity comparable to that of Glibenclamide and Metformin. This study confirms the polyherbal combination of T. officinale and M. charantia to be rich in various bioactive compounds, which exhibited antidiabetic properties. Therefore, this polyherbal combination has the potential to be further developed as complex phytotherapeutic remedy for the treatment of Type 2 Diabetes Mellitus.
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- 2022
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23. An Experimental Investigation on the Characteristics of a Compression Ignition Engine Fuelled by Diesel-Palm Biodiesel–Ethanol/Propanol Based Ternary Blends
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Navaneetha Krishnan Balakrishnan, Yew Heng Teoh, Heoy Geok How, Thanh Danh Le, and Huu Tho Nguyen
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biodiesel ,alcohol ,ternary blends ,sustainable fuel ,CI engine ,Technology - Abstract
Issues such as rising fuel prices, fuel costs, and lowering reserves highlight the importance of research into sustainable fuels derived from biological sources. This study is focused on experiments on a CI engine using ethanol and propanol-based ternary blends. Palm biodiesel is kept constant at 40% volumetric concentration, while diesel and ethanol/propanol are varied in different batches. The results obtained with ternary blends were compared with reference fuel diesel, pure palm biodiesel, and a palm biodiesel–diesel binary blend. The ternary blends exhibit lower brake thermal efficiency and higher brake specific energy consumption than diesel and binary blends due to their lower calorific value. Despite in-fuel oxygen presence, lower brake specific oxides of nitrogen and smoke opacity were observed for engine operation with a ternary blend due to the predominant role of higher latent heat of vaporization and volatility of alcohols, but unburned hydrocarbon and carbon monoxide emissions increased due to the interactive effect of a lower cetane number, higher latent heat of vaporization, and lower kinematic viscosity of alcohols when compared to reference fuels. Among the tested fuels, in-cylinder pressure was observed to decrease with ternary blends due to their lower calorific value, but a raised heat release rate was attributed to lower viscosity and faster burning of alcohols.
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- 2023
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24. A Review of the Emulsification Method for Alternative Fuels Used in Diesel Engines
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Mohd Fadzli Hamid, Yew Heng Teoh, Mohamad Yusof Idroas, Mazlan Mohamed, Shukriwani Sa’ad, Sharzali Che Mat, Muhammad Khalil Abdullah, Thanh Danh Le, Heoy Geok How, and Huu Tho Nguyen
- Subjects
emulsified biofuel ,neat biofuel ,surfactant ,alternative fuels ,microemulsion ,Technology - Abstract
Diesel engines are one of the most popular reciprocating engines on the market today owing to their great thermal efficiency and dependability in energy conversion. Growing concerns about the depletion of fossil resources, fluctuating prices in the market, and environmental issues have prompted the search for renewable fuels with higher efficiencies compared with conventional fuels. Fuel derived from vegetable oils and animal fats has comparable characteristics to diesel fuel, but is renewable, despite being manufactured from various feedstocks. Nevertheless, the direct use of these fuels is strictly prohibited because it will result in many issues in the engine, affecting engine performance and durability, as well as emissions. To make biofuels as efficient as fossil fuels, it is essential to alter their characteristics. The use of emulsification techniques to obtain emulsified biofuels is one of the many ways to modify the fuel characteristics. Emulsification techniques allow for a decrease in viscosity and an increase in atomisation during injection. To date, emulsification techniques have been studied less thoroughly for use with vegetable oils and animal fats. This article will discuss the preparation and characterisation of emulsified biofuels made from vegetable oils and animal fats. This current paper reviewed research studies carried out on different emulsification techniques for biofuels used in diesel engines.
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- 2022
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25. Experimental Studies of Combustion and Emission Characteristics of Biomass Producer Gas (BPG) in a Constant Volume Combustion Chamber (CVCC) System
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Jun Sheng Teh, Yew Heng Teoh, Heoy Geok How, Mohamad Yusof Idroas, Thanh Danh Le, and Huu Tho Nguyen
- Subjects
renewable energy ,biomass producer gas ,constant volume combustion chamber ,flame propagation ,chamber pressure ,emission ,Technology - Abstract
Most of the world’s energy requirements are still derived from natural resources. This will result in a catastrophic energy crisis with negative environmental consequences. The increased energy supply will result in greater consumption of non-renewable sources. The production of biomass producer gas (BPG) from biomass gasification has received significant attention as an alternative fuel due to the depletion of non-renewable resources. This experimental study aimed to determine the flame propagation, flame propagation speed, and chamber pressure trace of BPG at different equivalence ratios. Understanding the characteristics of the BPG’s combustion, finding lower greenhouse gas emissions of BPG, and minimizing the use of fossil fuels is necessary to mitigate these problems. Using the direct visualization technique, an optical constant volume combustion chamber (CVCC) was developed to measure combustion characteristics. Liquid petroleum gas (LPG) was used to compare the flame propagation speed in the CVCC calibration. In comparison to wood pellet (WP), coconut husk (CH), and palm kernel shell (PKS), the chamber peak pressure at ϕ equal to 1 of CH for the combustion of BPG was the lowest at 20.84 bar. At ϕ of 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, and 1.3, the chamber peak pressure of CH was discovered to be around 17.77, 18.12, 18.81, 20.84, 20.39, 17.25, and 16.37 bar, respectively. Compared to the other two types of BPG, CH produced the lowest emissions of CO2 and CO at 2.03% and 0.022%, respectively. In conclusion, the CH had the lowest chamber peak pressure and emissions due to the lower heating value (LHV) being relatively lower.
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- 2022
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26. Enhancement in Structural and Electroluminescence Properties of Green Light Emission for Semipolar (11–22) InGaN/GaN Based Grown on m-Plane Sapphire via Low Temperature Ammonia Treatment (LTAT)
- Author
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Gary Tan, Ahmad Shuhaimi, Rizuan Norhaniza, Norhilmi Zahir, Yan Jie Low, Yew Hoong Wong, and Wan Haliza Abd Majid
- Subjects
semipolar (11–22) ,InGaN/GaN ,low temperature ammonia treatment (LTAT) ,green emission ,effective V/III ,Applied optics. Photonics ,TA1501-1820 - Abstract
Research on enhancement green light emitter is important to obtain a perfect red-green-blue (RGB) induced white light source. Unfortunately the present of mixed phase in deposition of InGaN/GaN limited the potential LED efficiency. Therefore, we introduce a new method called as Low Temperature Ammonia Treatment (LTAT) to eliminate the mixed phase and to enhance the structure properties of InGaN/GaN. Two samples have been prepared, with LTAT (LED A) and without LTAT (LED B). Both samples have been characterized using optical microscope (OM), Atomic Force Microscope (AFM), X-ray rocking curve (XRC) and Electroluminescence (EL). On the structural characterization, the OM results show the present 3D island on LED B sample while sample LED A only shows 2D surface. The RMS surface roughness from AFM are 10.3 ± 0.4 nm and 13.5 ± 10.7 nm for LED A and LED B respectively. XRC analysis proved the LED A with LTAT has a homogenous XRD curve while LED B without LTAT has a mixed phase. The BSFs streak length measured as 1.42 nm−1 and 1.61 nm−1 for LED A and LED B respectively shows low crystallographic defect in LED A compared to LED B. For the EL characteristic, LED A shows a single sharp peak near 538.2 nm wavelength, while LED B shows a broad multi-peak profile at 435.7 nm, 480.6 nm and 520.5 nm. The single sharp peak shows enhancement in green light emission when LTAT is applied during deposition. Successful enhancement is structural and electroluminescence properties shows the effectiveness of LTAT proposed in this work for perfect RGB.
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- 2022
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27. Energy evaluation and environmental impact assessment of transportation fuels in Pakistan
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Haseeb Yaqoob, Yew Heng Teoh, Talha S. Goraya, Farooq Sher, Muhammad Ahmad Jamil, Tazien Rashid, and Kashif Allah Yar
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Renewable energy ,Optimum fuel ,Energy security ,Sustainable environment ,Alternative fuels ,Fossil fuels and Emissions ,Environmental engineering ,TA170-171 ,Chemical engineering ,TP155-156 - Abstract
The recent studies emphasize the importance of modern technologies and the reduction of gases emission while neglecting the significance of the optimum fuel. A comprehensive comparison for compressed natural gas, liquified natural gas, liquified petroleum gas, gasoline, electricity, diesel, and alternative fuels such as bioethanol and biodiesel as a transport fuel is carried out for Pakistan. The comparison is carried out by undertaking various factor that affects the fuel economy. Therefore, a comparison of fuel properties, production, consumption, emission of gases, engine performance and economy are carried to observe the optimum fuel for Pakistan. It concluded that compressed natural gas, electricity, and alternative fuels were found to be the optimum fuel for the environment and economy of Pakistan and having a high potential for its availability through different sources. Besides, strategy and future policies and directions are also discussed for the optimum fuel. Moreover, the future of vehicles is also discussed to analyze the transportation trend of the world. The present study will be very efficient for the optimum fuel consideration and growing future for developing countries. Therefore, Pakistan should pay attention to these fuels for their production, implementation, and electric vehicles for a sustainable future.
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- 2021
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28. Induced Macrolide Resistance in Mycoplasma genitalium Isolates from Patients with Recurrent Nongonococcal Urethritis
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Yew, H. S., primary, Anderson, T., additional, Coughlan, E., additional, and Werno, A., additional
- Published
- 2011
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29. Session 55: PCOS 2
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Barad, D., primary, Gupta, A., additional, Gleicher, N., additional, Puurunen, J., additional, Piltonen, T., additional, Morin-Papunen, L., additional, Ruokonen, A., additional, Tapanainen, J. S., additional, Villarroel, C., additional, Lopez, P., additional, Merino, P., additional, Van Velzen, A., additional, Iniguez, G., additional, Codner, E., additional, El-Sherbiny, W., additional, Al-Inany, H., additional, Ibrahim, M., additional, Harb, H., additional, Richardson, M., additional, Yew, H. C., additional, Simonis, C. D., additional, Byrne, C. D., additional, Cheong, Y., additional, Matteo, M., additional, Greco, P., additional, Santopietro, X., additional, Noviello, A., additional, De Rosario, M., additional, Cho, Y., additional, Falagario, T., additional, Totaro, R., additional, Massenzio, F., additional, Liso, A., additional, Serviddio, G., additional, Garcia-Gamon, M., additional, Romeu, M., additional, Monzo, A., additional, Montanana, V., additional, Perez-Calvo, A., additional, Tresguerres, J., additional, and Romeu, A., additional
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- 2010
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30. Crosstalk Between Scavenger Receptors (SR-A) and Toll-like Receptors (TLR) Results in Rapid Pro-Inflammatory Cytokine Differentiation in Monocytes Exposed to Cytomegalovirus (CMV)
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YEW, H, primary and HARRISON, C, additional
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- 2007
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31. Interaction Matrix for Planning Underground Ammunition Storage Facilities
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LANDS AND ESTATES ORGANIZATION (SINGAPORE), Zhou, Yingxin, Lim, Chee H, Ong, Yew H, LANDS AND ESTATES ORGANIZATION (SINGAPORE), Zhou, Yingxin, Lim, Chee H, and Ong, Yew H
- Abstract
A systematic approach to planning underground ammunition storage based on an interaction matrix is presented. The interaction matrix is essentially a collection of the most important parameters with all possible interactions among them. Depending on the objectives of planning and design, several levels of the interaction matrix can be designed with the highest level having the least details, and the lowest level being complete with all relevant parameters included, which can be used for final planning and design. The advantages of the interaction matrix is that it gives you an overall picture at varying degrees of details. One parameter can not be changed without knowing its effects on the rest of the system. It also allows one to gather all relevant factors and mechanisms in a coherent structure. In this paper the basic structure of the interaction matrix is presented. Practical examples are then used to demonstrate the use of this system., See also ADM000767. Proceedings of the DoD Explosives Safety Seminar (27th) Held in Las Vegas, NV on 22-26 August 1996.
- Published
- 1996
32. Optimal wavelet tree pruning for image coding
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Ang, Yew H., primary, Bi, M., additional, and Ong, Sim Heng, additional
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- 1995
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33. Image retrieval based on multidimensional feature properties
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Ang, Yew H., primary, Li, Z., additional, and Ong, Sim Heng, additional
- Published
- 1995
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34. A Review on the Enhancement of Calcium Phosphate Cement with Biological Materials in Bone Defect Healing
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Sok Kuan Wong, Yew Hoong Wong, Kok-Yong Chin, and Soelaiman Ima-Nirwana
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biomaterials ,hydroxyapatite ,polysaccharide ,protein ,transcription factor ,platelet-rich plasma ,Organic chemistry ,QD241-441 - Abstract
Calcium phosphate cement (CPC) is a promising material used in the treatment of bone defects due to its profitable features of self-setting capability, osteoconductivity, injectability, mouldability, and biocompatibility. However, the major limitations of CPC, such as the brittleness, lack of osteogenic property, and poor washout resistance, remain to be resolved. Thus, significant research effort has been committed to modify and reinforce CPC. The mixture of CPC with various biological materials, defined as the materials produced by living organisms, have been fabricated by researchers and their characteristics have been investigated in vitro and in vivo. This present review aimed to provide a comprehensive overview enabling the readers to compare the physical, mechanical, and biological properties of CPC upon the incorporation of different biological materials. By mixing the bone-related transcription factors, proteins, and/or polysaccharides with CPC, researchers have demonstrated that these combinations not only resolved the lack of mechanical strength and osteogenic effects of CPC but also further improve its own functional properties. However, exceptions were seen in CPC incorporated with certain proteins (such as elastin-like polypeptide and calcitonin gene-related peptide) as well as blood components. In conclusion, the addition of biological materials potentially improves CPC features, which vary depending on the types of materials embedded into it. The significant enhancement of CPC seen in vitro and in vivo requires further verification in human trials for its clinical application.
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- 2021
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35. Determination of interfacial roughness correlation in W/C multilayer films: comparison using soft and hard x-ray diffraction
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Savage, Don E., primary, Phang, Yew-H., additional, Rownd, J. J., additional, MacKay, James F., additional, and Lagally, Max G., additional
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- 1994
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36. Colour Stability of Composite Resins: A General Overview.
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Yew, H. Z. and Qamaruz Zaman, J.
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DENTAL resins ,DENTAL discoloration ,COSMETIC dentistry - Abstract
Composite resins have been shown to be susceptible to discolouration on exposure to oral environment over a period of time. Discolouration of composite resins can be broadly classified as intrinsic or extrinsic. Intrinsic discolouration involves physico-chemical alteration within the material, while extrinsic stains are a result of surface discolouration by extrinsic compounds. Although the effects of various substances on the colour stability of composite resins have been extensively investigated, little has been published on the methods of removing the composite resins staining. The purpose of this paper is to provide a brief literature review on the colour stability of composite resins and clinical approaches in the stain removal. [ABSTRACT FROM AUTHOR]
- Published
- 2012
37. Influence of formulations on textural, mechanical and structural breakdown properties of cooked yellow alkaline noodles.
- Author
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Foo, W. T., Yew, H. S., Liong, M. T., and Azhar, M. E.
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COOKING ,ENZYMES ,TRANSGLUTAMINASES ,TRANSFERASES ,FLOUR ,NOODLES - Abstract
The physical attributes (pH and colour), cooking yield, textural and mechanical properties (firmness, tensile and texture profiles analyses) and structural breakdown properties (multiple extrusion cell with added artificial saliva) of five yellow alkaline noodle (YAN) formulations were studied. Samples used were noodles with (a) typical formulation (control), (b) soy protein isolate (SPI), (c) soy protein isolate plus microbial transglutaminase enzyme (SPI/MTGase), (d) green banana pulp flour (GBPu) and (e) green banana peel flour (GBPe). Compared to other noodles SPI/MTGase noodle showed significantly (P < 0.05) higher values in terms of textural, mechanical and breakdown properties. Incorporating SPI, banana pulp and peel flours into the noodles had imposed some differences on most of the mechanical and textural parameters from the control YAN. However, these noodles could not be clearly distinguished in term of structural breakdown properties. [ABSTRACT FROM AUTHOR]
- Published
- 2011
38. Image retrieval based on multidimensional feature properties.
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Ang, Yew H., Li, Z., and Ong, Sim Heng
- Published
- 1995
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39. Optimization of Fuel Injection Parameters of Moringa oleifera Biodiesel-Diesel Blend for Engine-Out-Responses Improvements
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Yew Heng Teoh, Heoy Geok How, Farooq Sher, Thanh Danh Le, Hwai Chyuan Ong, Huu Tho Nguyen, and Haseeb Yaqoob
- Subjects
renewable fuels ,moringa biodiesel ,common-rail ,combustion ,optimization ,alternative fuel ,Mathematics ,QA1-939 - Abstract
Biodiesel has gained popularity in diesel engines as a result of the rapid decline of fossil fuels and population growth. The processing of biodiesel from non-edible Moringa Oleifera was investigated using a single-step transesterification technique. Both fuels had their key physicochemical properties measured and investigated. In a common-rail diesel engine, the effects of MB50 fuel blend on the symmetric characteristics of engine-out responses were evaluated under five load settings and at 1000 rpm. As compared to standard diesel, MB50 increased brake thermal efficiency (BTE), and nitrogen oxides (NOx) emissions while lowering brake specific fuel consumption (BSFC), and smoke emissions for all engine loads. A further study of injection pressure and start of injection (SOI) timing for MB50 fuel was optimized using response surface methodology (RSM). The RSM optimization resulted in improved combustion dynamics due to symmetry operating parameters, resulting in a simultaneous decrease in NOx and smoke emissions without sacrificing BTE. RSM is an efficient optimization method for achieving optimal fuel injection parameter settings, as can be deduced. As a result, a clearer understanding of the use of MB50 fuel in diesel engines can be given, allowing for the best possible engine efficiency.
- Published
- 2021
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- View/download PDF
40. Experimental Investigations of a Solar Water Treatment System for Remote Desert Areas of Pakistan
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Muhammad Ahmad Jamil, Haseeb Yaqoob, Muhammad Umar Farooq, Yew Heng Teoh, Ben Bin Xu, Khamid Mahkamov, Muhammad Sultan, Kim Choon Ng, and Muhammad Wakil Shahzad
- Subjects
arid areas ,Pakistan ,passive desalination system ,water scenario ,solar still ,Hydraulic engineering ,TC1-978 ,Water supply for domestic and industrial purposes ,TD201-500 - Abstract
Pakistan is among the countries that have already crossed the water scarcity line, and the situation is worsened due to the recent pandemic. This is because the major budget of the country is shifted to primary healthcare activities from other development projects that included water treatment and transportation infrastructure. Consequently, water-borne diseases have increased drastically in the past few months. Therefore, there is a dire need to address this issue on a priority basis to ameliorate the worsening situation. One possible solution is to shift the focus/load from mega-projects that require a plethora of resources, money, and time to small domestic-scale systems for water treatment. For this purpose, domestic-scale solar stills are designed, fabricated, and tested in one of the harshest climatic condition areas of Pakistan, Rahim Yar Khan. A comprehensive overview of the regional climatology, including wind speed, solar potential, and ambient temperature is presented for the whole year. The analysis shows that the proposed system can adequately resolve the drinking water problems of deprived areas of Pakistan. The average water productivity of 1.5 L/d/m2 is achieved with a total investment of PKR 3000 (
- Published
- 2021
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41. Potential of Waste Cooking Oil Biodiesel as Renewable Fuel in Combustion Engines: A Review
- Author
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Haseeb Yaqoob, Yew Heng Teoh, Farooq Sher, Muhammad Umer Farooq, Muhammad Ahmad Jamil, Zareena Kausar, Noor Us Sabah, Muhammad Faizan Shah, Hafiz Zia Ur Rehman, and Atiq Ur Rehman
- Subjects
renewable energy ,alternative fuel ,biodiesel ,waste cooking oil ,diesel engine ,emissions ,Technology - Abstract
As non-renewable conventional fossil fuel sources are depleting day by day, researchers are continually finding new ways of producing and utilizing alternative, renewable, and reliable fuels. Due to conventional technologies, the environment has been degraded seriously, which profoundly impacts life on earth. To reduce the emissions caused by running the compression ignition engines, waste cooking oil (WCO) biodiesel is one of the best alternative fuels locally available in all parts of the world. Different study results are reviewed with a clear focus on combustion, performance, and emission characteristics, and the impact on engine durability. Moreover, the environmental and economic impacts are also reviewed in this study. When determining the combustion characteristics of WCO biodiesel, the cylinder peak pressure value increases and the heat release rate and ignition delay period decreases. In performance characteristics, brake-specific fuel consumption increases while brake-specific energy consumption, brake power, and torque decrease. WCO biodiesel cuts down the emissions value by 85% due to decreased hydrocarbon, SO2, CO, and smoke emissions in the exhaust that will effectively save the environment. However, CO2 and NOx generally increase when compared to diesel. The overall economic impact of production on the utilization of this resource is also elaborated. The results show that the use of WCO biodiesel is technically, economically, environmentally, and tribologically appropriate for any diesel engine.
- Published
- 2021
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- View/download PDF
42. An Experimental Investigation on the Effect of Ferrous Ferric Oxide Nano-Additive and Chicken Fat Methyl Ester on Performance and Emission Characteristics of Compression Ignition Engine
- Author
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Ameer Suhel, Norwazan Abdul Rahim, Mohd Rosdzimin Abdul Rahman, Khairol Amali Bin Ahmad, Yew Heng Teoh, and Noh Zainal Abidin
- Subjects
chicken fat methyl ester ,ferrous ferric oxide ,compression ignition engine ,performance and emission ,Mathematics ,QA1-939 - Abstract
In recent years, industries have been investing to develop a potential alternative fuel to substitute the depleting fossil fuels which emit noxious emissions. Present work investigated the effect of ferrous ferric oxide nano-additive on performance and emission parameters of compression ignition engine fuelled with chicken fat methyl ester blends. The nano-additive was included with various methyl ester blends at different ppm of 50, 100, and 150 through the ultrasonication process. Probe sonicator was utilized for nano-fuel preparation to inhibit the formation of agglomeration of nanoparticles in base fuel. Experimental results revealed that the addition of 100 ppm dosage of ferrous ferric oxide nanoparticles in blends significantly improves the combustion performance and substantially decrease the pernicious emissions of the engine. It is also found from an experimental results analysis that brake thermal efficiency (BTE) improved by 4.84%, a reduction in brake specific fuel consumption (BSFC) by 10.44%, brake specific energy consumption (BSEC) by 9.44%, exhaust gas temperature (EGT) by 19.47%, carbon monoxides (CO) by 53.22%, unburned hydrocarbon (UHC) by 21.73%, nitrogen oxides (NOx) by 15.39%, and smoke by 14.73% for the nano-fuel B20FFO100 blend. By seeing of analysis, it is concluded that the doping of ferrous ferric oxide nano-additive in chicken fat methyl ester blends shows an overall development in engine characteristics.
- Published
- 2021
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43. Analysis of labour market needs for engineers with enhanced knowledge in sustainable renewable energy solutions in the built environment in some Asian countries
- Author
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Cioccolanti Luca, Moglie Matteo, Mahkamov Khamid, Paksoy Halime, Chen Chao, Lin Jie, Li Caiyun, Guan Yong, Zhou Wenhe, Abdullah Ermira, Mohd Radzi Mohd Amran, Shafie Suhaidi, Alimuddin Zainal, Yusof Idroas Mohamad, Yew Heng Teoh, Azmier Ahmad Mohd, Azman Miskam Muhamad, Kraitong Kwanchai, Wongsapai Wongkot, Chaichana Chatchawan, and Damronsak Det
- Subjects
Environmental sciences ,GE1-350 - Abstract
Despite the rapid growth in the uptake of renewable energy technologies, the educational profile and the skills gained at University level do not always comply with the practical needs of the organisations working in the field. Furthermore, even though the residential sector has very high potential in curbing its CO2 emissions worldwide thus meeting the challenging goals set out by the international agreements, such reduction has been limited so far. Within this context, the ‘Skybelt’ project, co-funded by the EU under the framework of the Erasmus + programme aims at enhancing in several Universities of Asia and Europe the engineering skills of students of all level for application of sustainable renewable energy solutions in the built environment. With the target of increasing the employability of graduates and the impact of the project, a survey on the labour market needs for specialists with enhanced knowledge and skills in the topic of the project has been conducted in the related Asian countries. Hence, relevant industries, labour market organisations and other stakeholders have been interviewed and the main results of this analysis is reported in the present paper. As first outcome of this activity, the obtained results have been considered in the selection of the modules to be improved according to a student centred study approach.
- Published
- 2021
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- View/download PDF
44. Role of OCB and demographic factors in the relationship of motivation and employee performance
- Author
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Yew Huei Tan and Nur Naha Abu Mansor
- Subjects
Intrinsic motivation, extrinsic motivation, OCB, employee performance, gender and organizational tenure ,General Works - Abstract
Purpose: This research seeks to broaden the study by investigating the interplay of organizational citizenship behaviour (OCB) and demographic factor (gender and organizational tenure) on the motivation and employee performance relationship.Design/methodology/approach: Multiple linear regression was used to test the relationship between motivation (intrinsic and extrinsic) and employee performance among (n=368) lecturers in Malaysia. To test the mediating effect of OCB, path analysis was employed. Furthermore, the demographic factors (gender and organizational tenure) was tested using the moderated multiple regression analysis.Findings: Significant differences in explaining the variance of employee performance was found between intrinsic motivation and extrinsic motivation. In addition, OCB was found perfectly mediating the relationship of extrinsic motivation and employee performance, however, OCB was found partially mediating the relationship between intrinsic motivation and employee performance. Furthermore, gender and organizational tenure do not show any moderate results in the relationship between OCB and employee performance.Research limitations: Study limitations (e.g. cross-sectional research design and biasness) and future opportunities are outlined.Practical implications: Argues that the suitable type of motivation in explaining the variances of employee performance. Also, identifies the important of OCB between the motivation and employee performance relationship, thus gender and organizational tenure were not significant to OCB and employee performance relationship.Social implications: HR can help an organization to succeed, provided that the suitable motivations are adopted to monitor lecturer performance and helping behavior. In addition, HR should not emphasize too much of gender and organizational tenure to justify the lecturer performance as the findings show insignificant relationship.Originality/value: This paper identifies and discusses the types of motivation that explain higher variance of employee performance and how OCB play role as mediator in the motivation and employee performance relationship. In addition, the moderating effect of gender and organizational tenure were also discussed. This is the first attempt to include all the variables in the same theoretical framework.
- Published
- 2014
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45. Development of a novel flexible composite material
- Author
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Ramakrishna, S., Huang, Z. Ming, and Yew, H. M.
- Published
- 1999
- Full Text
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46. Photophysical and Electroluminescence Characteristics of Polyfluorene Derivatives with Triphenylamine
- Author
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Qiang Zhang, Po-I. Wang, Guang Liang Ong, Shen Hoong Tan, Zhong Wei Tan, Yew Han Hii, Yee Lin Wong, Khee Sang Cheah, Seong Ling Yap, Teng Sian Ong, Teck Yong Tou, Chen Hon Nee, Der Jang Liaw, and Seong Shan Yap
- Subjects
semiconducting polymer ,electroluminescence ,polyfluorene ,triphenylamine ,PLED ,Suzuki coupling ,OLED ,Organic chemistry ,QD241-441 - Abstract
In this work, polymers of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-triphenylamine] with side chains containing: pyrene (C1), diphenyl (C2), naphthalene (C3), and isopropyl (C6) structures were synthesized via a Suzuki coupling reaction. The structures were verified using NMR and cyclic voltammetry measurements provide the HOMO and LUMO of the polymers. The polymer with pyrene (C1) and naphthalene (C3) produced photoluminescence in the green while the polymer with the side chain containing diphenyl (C2) and isopropyl (C6) produce dual emission peaks of blue-green photoluminescence (PL). In order to examine the electroluminescence properties of the polymers, the solutions were spin-coated onto patterned ITO anode, dried, and subsequently coated with an Al cathode layer to form pristine single layer polymer LEDs. The results are compared to a standard PFO sample. The electroluminescence spectra resemble the PL spectra for C1 and C3. The devices of C2, C3, and C6 exhibit voltage-dependent EL. An additional red emission peak was detected for C2 and C6, resulting in spectra with peaks at 435 nm, 490 nm, and 625 nm. The effects of the side chains on the spectral characteristics of the polymer are discussed.
- Published
- 2019
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- View/download PDF
47. Physicochemical, Performance, Combustion and Emission Characteristics of Melaleuca Cajuputi Oil-Refined Palm Oil Hybrid Biofuel Blend
- Author
-
Sharzali Che Mat, Mohamad Yusof Idroas, Yew Heng Teoh, and Mohd Fadzli Hamid
- Subjects
Melaleuca Cajuputi oil ,refined palm oil ,hybrid biofuel ,viscosity ,binary blend ,Technology - Abstract
To reduce the economic impact caused by the fossil fuel crisis and avoid relying on existing biofuels, it is important to seek locally available and renewable biofuel throughout the year. In the present work, a new light biofuel—Melaleuca Cajuputi oil (MCO)—was introduced to blend with refined palm oil (RPO). The physicochemical properties, combustion characteristics, engine performance, and exhaust emissions were comprehensively examined. It was found that the higher the percentage of MCO, the lower the viscosity and density of the blends obtained. Calorific value (CV) was increased with the increase of MCO fraction in the blend. Regression analysis has suggested that the blend of 32% (v/v) of RPO and 68% (v/v) of MCO (RPO32MCO68) is optimal to obtain viscosity and density in accordance with ASTM 6751/EN 14214 standards. The experimental results show that the in-cylinder pressure, brake torque, and brake power of the optimal blend were slightly lower than those of baseline diesel fuel. Brake specific fuel consumption (BSFC), carbon monoxide (CO), and unburnt hydrocarbon (HC) were found to be slightly higher compared to diesel fuel. Notably, nitrogen oxides (NOx) and smoke opacity were found to be decreased over the entire range of the test. Overall, the optimal blend of RPO32MCO68 has shown a decent result which marks it as a potential viable source of biofuel.
- Published
- 2018
- Full Text
- View/download PDF
48. Cytotoxicity and Toxicity Evaluation of Xanthone Crude Extract on Hypoxic Human Hepatocellular Carcinoma and Zebrafish (Danio rerio) Embryos
- Author
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Shazrul Fazry, Muhammad Akram Mohd Noordin, Salahuddin Sanusi, Mahanem Mat Noor, Wan Mohd Aizat, Azwan Mat Lazim, Herryawan Ryadi Eziwar Dyari, Nur Hidayah Jamar, Juwairiah Remali, Babul Airianah Othman, Douglas Law, Nik Marzuki Sidik, Yew Hoong Cheah, and Yi Chieh Lim
- Subjects
xanthone ,α-mangostin ,HPLC ,MTT proliferation assay ,fish embryo toxicity test ,Chemical technology ,TP1-1185 - Abstract
Xanthone is an organic compound mostly found in mangosteen pericarp and widely known for its anti-proliferating effect on cancer cells. In this study, we evaluated the effects of xanthone crude extract (XCE) and α-mangostin (α-MG) on normoxic and hypoxic human hepatocellular carcinoma (HepG2) cells and their toxicity towards zebrafish embryos. XCE was isolated using a mixture of acetone and water (80:20) and verified via high performance liquid chromatography (HPLC). Both XCE and α-MG showed higher anti-proliferation effects on normoxic HepG2 cells compared to the control drug, 5-fluorouracil (IC50 = 50.23 ± 1.38, 8.39 ± 0.14, and 143.75 ± 15.31 μg/mL, respectively). In hypoxic conditions, HepG2 cells were two times less sensitive towards XCE compared to normoxic HepG2 cells (IC50 = 109.38 ± 1.80 μg/mL) and three times less sensitive when treated with >500 μg/mL 5-fluorouracil (5-FU). A similar trend was seen with the α-MG treatment on hypoxic HepG2 cells (IC50 = 10.11 ± 0.05 μg/mL) compared to normoxic HepG2 cells. However, at a concentration of 12.5 μg/mL, the α-MG treatment caused tail-bend deformities in surviving zebrafish embryos, while no malformation was observed when embryos were exposed to XCE and 5-FU treatments. Our study suggests that both XCE and α-MG are capable of inhibiting HepG2 cell proliferation during normoxic and hypoxic conditions, more effectively than 5-FU. However, XCE is the preferred option as no malformation was observed in surviving zebrafish embryos and it is more cost efficient than α-MG.
- Published
- 2018
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- View/download PDF
49. The tunable permittivity of multi-walled carbon nanotubes/silver nanoparticles reinforced polyvinyl alcohol (PVA) nanocomposites at low frequency
- Author
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Yusliza Yusof, Zi Yi Ng, Yew Hoong Wong, and Mohd Rafie Johan
- Subjects
carbon nanotubes ,silver nanoparticles ,permittivity ,conductivity ,microscopy ,Materials of engineering and construction. Mechanics of materials ,TA401-492 ,Chemical technology ,TP1-1185 - Abstract
This paper is about tailoring high permittivity of multi-walled carbon nanotubes/silver nanoparticles (MWNT-AgNP) filled polyvinyl alcohol (PVA) nanocomposites at low frequency. PVA/MWNT-AgNP nanocomposites were synthesized via solution-casting technique at low MWNT content with different loading of AgNP. The nanocomposites showed a significant increment in ac conductivity, σ _ac , and dielectric permittivity, ε ′ by two orders of magnitude as compared to pure PVA. The maximum ε ′ value was achieved about 600 at 1.0 wt% of AgNP due to the increased charge carriers density and high interfacial polarization within the nanocomposites. The relaxation frequency was shifted towards a higher value with the increased of AgNP content while the relaxation time was decreased by 40%. Field emission scanning electron microscopy (FESEM) images showed the enhanced distribution of MWNT in the presence of AgNP to provide conductive pathways in the matrix. This was confirmed by energy-dispersive x-ray (EDX) analysis and ultraviolet-visible (UV–vis) spectroscopy. As a result, PVA/MWNT-AgNP nanocomposites have great potential for electrical applications such as cable accessories, high charge-storage capacitor and electromagnetic interference shielding materials.
- Published
- 2018
- Full Text
- View/download PDF
50. Assessing intracellular pH regulation in H+-ATPase-rich ionocytes in zebrafish larvae using in vivoratiometric imaging
- Author
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Yew, H. M., Zimmer, A. M., and Perry, S. F.
- Abstract
The H+-ATPase-rich (HR) cells of zebrafish larvae are a sub-type of ion-transporting cell located on the yolk sac epithelium that are responsible for Na+uptake and H+extrusion. Current models of HR cell ion transport mechanisms in zebrafish larvae are well established, but little is known about the involvement of the various ion transport pathways in regulating intracellular acid–base status. Here, a ratiometric imaging technique was developed and validated to monitor intracellular pH (pHi) continuously in larval zebrafish HR cells in vivo. Gene knockdown or CRISPR/Cas9 knockout approaches were used to evaluate the roles of the two principal apical membrane acid excretory pathways, the Na+/H+exchanger (NHE3b; slc9a3.2) and the H+-ATPase (atpv1aa). Additionally, the role of HR cell cytosolic carbonic anhydrase (CAc) was investigated because of its presumed role in providing H+for Na+/H+exchange and H+-ATPase. The temporal pattern and extent of intracellular acidification during exposure of fish to 1% CO2and the extent of post-CO2alkalisation were altered markedly in fish experiencing knockdown/knockout of CAc, NHE3b or H+-ATPase. Although there were slight differences among the three knockdown/knockout experiments, the typical response was a greater degree of intracellular acidification during CO2exposure and a reduced capacity to restore pHi to baseline levels post-hypercapnia. The metabolic alkalosis and subsequent acidification associated with 20 mmol l−1NH4Cl exposure and its washout were largely unaffected by gene knockdown. Overall, the results suggest markedly different mechanisms of intracellular acid–base regulation in zebrafish HR cells depending on the nature of the acid–base disturbance.
- Published
- 2020
- Full Text
- View/download PDF
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