Displaying publications 21 - 40 of 73 in total

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  1. Fulltext Co-pyrolysis of medical protective clothing and oil palm wastes for biofuel: Experimental, techno-economic, and environmental analyses
    Su G, Zulkifli NWM, Ong HC, Ibrahim S, Cheah MY, Zhu R, et al.
    Energy (Oxf), 2023 Jun 15;273:127221.
    PMID: 36942281 DOI: 10.1016/j.energy.2023.127221
    The ongoing global pandemic of COVID-19 has devastatingly influenced the environment, society, and economy around the world. Numerous medical resources are used to inhibit the infectious transmission of the virus, resulting in massive medical waste. This study proposes a sustainable and environment-friendly method to convert hazardous medical waste into valuable fuel products through pyrolysis. Medical protective clothing (MPC), a typical medical waste from COVID-19, was utilized for co-pyrolysis with oil palm wastes (OPWs). The utilization of MPC improved the bio-oil properties in OPWs pyrolysis. The addition of catalysts further ameliorated the bio-oil quality. HZSM-5 was more effective in producing hydrocarbons in bio-oil, and the relevant reaction pathway was proposed. Meanwhile, a project was simulated to co-produce bio-oil and electricity from the co-pyrolysis of OPWs and MPC from application perspectives. The techno-economic analysis indicated that the project was economically feasible, and the payback period was 6.30-8.75 years. Moreover, it was also environmentally benign as its global warming potential varied from -211.13 to -90.76 kg CO2-eq/t. Therefore, converting MPC and OPWs into biofuel and electricity through co-pyrolysis is a green, economic, and sustainable method that can decrease waste, produce valuable fuel products, and achieve remarkable economic and environmental benefits.
  2. Co-pyrolysis of microalgae and other biomass wastes for the production of high-quality bio-oil: Progress and prospective
    Su G, Ong HC, Gan YY, Chen WH, Chong CT, Ok YS
    Bioresour Technol, 2022 Jan;344(Pt B):126096.
    PMID: 34626763 DOI: 10.1016/j.biortech.2021.126096
    Microalgae are the most prospective raw materials for the production of biofuels, pyrolysis is an effective method to convert biomass into bioenergy. However, biofuels derived from the pyrolysis of microalgae exhibit poor fuel properties due to high content of moisture and protein. Co-pyrolysis is a simple and efficient method to produce high-quality bio-oil from two or more materials. Tires, plastics, and bamboo waste are the optimal co-feedstocks based on the improvement of yield and quality of bio-oil. Moreover, adding catalysts, especially CaO and Cu/HZSM-5, can enhance the quality of bio-oil by increasing aromatics content and decreasing oxygenated and nitrogenous compounds. Consequently, this paper provides a critical review of the production of bio-oil from co-pyrolysis of microalgae with other biomass wastes. Meanwhile, the underlying mechanism of synergistic effects and the catalytic effect on co-pyrolysis are discussed. Finally, the economic viability and prospects of microalgae co-pyrolysis are summarized.
  3. Fulltext Cost-benefit analysis and emission reduction of energy efficient lighting at the Universiti Tenaga Nasional
    Ganandran GS, Mahlia TM, Ong HC, Rismanchi B, Chong WT
    ScientificWorldJournal, 2014;2014:745894.
    PMID: 25133258 DOI: 10.1155/2014/745894
    This paper reports the result of an investigation on the potential energy saving of the lighting systems at selected buildings of the Universiti Tenaga Nasional. The scope of this project includes evaluation of the lighting system in the Library, Admin Building, College of Engineering, College of Information Technology, Apartments, and COE Food court of the university. The main objectives of this project are to design the proper retrofit scenario and to calculate the potential electricity saving, the payback period, and the potential environmental benefits. In this survey the policy for retrofitting the old lighting system with the new energy saving LEDs starts with 10% for the first year and continues constantly for 10 years until all the lighting systems have been replaced. The result of the life cycle analysis reveals that after four years, the selected buildings will bring profit for the investment.
  4. Fulltext Design optimization of pin fin geometry using particle swarm optimization algorithm
    Hamadneh N, Khan WA, Sathasivam S, Ong HC
    PLoS One, 2013;8(5):e66080.
    PMID: 23741525 DOI: 10.1371/journal.pone.0066080
    Particle swarm optimization (PSO) is employed to investigate the overall performance of a pin fin.The following study will examine the effect of governing parameters on overall thermal/fluid performance associated with different fin geometries, including, rectangular plate fins as well as square, circular, and elliptical pin fins. The idea of entropy generation minimization, EGM is employed to combine the effects of thermal resistance and pressure drop within the heat sink. A general dimensionless expression for the entropy generation rate is obtained by considering a control volume around the pin fin including base plate and applying the conservations equations for mass and energy with the entropy balance. Selected fin geometries are examined for the heat transfer, fluid friction, and the minimum entropy generation rate corresponding to different parameters including axis ratio, aspect ratio, and Reynolds number. The results clearly indicate that the preferred fin profile is very dependent on these parameters.
  5. Fulltext Development and Validation of a Coping Scale for Caregivers in Malaysia
    Ibrahim N, Ong HC, Wahab S
    Malays J Med Sci, 2017 May;24(3):83-91.
    PMID: 28814936 MyJurnal DOI: 10.21315/mjms2017.24.3.10
    INTRODUCTION: Caregivers often experience stressful situations while in the midst of the caregiving process. Thus, various methods of coping have been widely applied and studied in previous researches. The aim of this study was to develop a novel questionnaire to assess the coping strategies employed by those who provide care to patients, and to further validate it among caregivers of schizophrenia patients in Malaysia.

    METHODS: This study, which involved the caregivers of schizophrenia patients from a hospital in Kuala Lumpur, Malaysia, was comprised of three parts, namely in-depth interviews, a pilot study, and the validation of the developed questionnaire, known as Caregiver Cope (CgCopeTM).

    RESULTS: Part A originally consisted of eight themes, and it was later modified to seven themes with four items each after discussions with some experts. Part B initially had 28 items derived from the seven themes in Part A, which were then reduced to six components after a factor analysis. Part C of the questionnaire consisted of 19 items, with six components (Distraction, Caring for patient, Venting, Religion, Recreation, and Social support) having a moderate to high reliability ranging from a Cronbach's alpha coefficient of 0.54 to 0.82. A factor analysis showed that the six factors of coping accounted for 62.36% of the total variance.

    CONCLUSION: The CgCOPETM questionnaire is suitable for use among caregivers of schizophrenia patients. There is a need to further validate the instrument among caregivers of other patient populations.

  6. Fulltext Effects of acids pre-treatment on the microbial fermentation process for bioethanol production from microalgae
    Phwan CK, Chew KW, Sebayang AH, Ong HC, Ling TC, Malek MA, et al.
    Biotechnol Biofuels, 2019;12:191.
    PMID: 31384298 DOI: 10.1186/s13068-019-1533-5
    Background: Microalgae are one of the promising feedstock that consists of high carbohydrate content which can be converted into bioethanol. Pre-treatment is one of the critical steps required to release fermentable sugars to be used in the microbial fermentation process. In this study, the reducing sugar concentration of Chlorella species was investigated by pre-treating the biomass with dilute sulfuric acid and acetic acid at different concentrations 1%, 3%, 5%, 7%, and 9% (v/v).

    Results: 3,5-Dinitrosalicylic acid (DNS) method, FTIR, and GC-FID were employed to evaluate the reducing sugar concentration, functional groups of alcohol bonds and concentration of bioethanol, respectively. The two-way ANOVA results (p 

  7. Engine performance and emission characteristics of palm biodiesel blends with graphene oxide nanoplatelets and dimethyl carbonate additives
    Razzaq L, Mujtaba MA, Soudagar MEM, Ahmed W, Fayaz H, Bashir S, et al.
    J Environ Manage, 2021 Mar 15;282:111917.
    PMID: 33453625 DOI: 10.1016/j.jenvman.2020.111917
    This study investigated the engine performance and emission characteristics of biodiesel blends with combined Graphene oxide nanoplatelets (GNPs) and 10% v/v dimethyl carbonate (DMC) as fuel additives as well as analysed the tribological characteristics of those blends. 10% by volume DMC was mixed with 30% palm oil biodiesel blends with diesel. Three different concentrations (40, 80 and 120 ppm) of GNPs were added to these blends via the ultrasonication process to prepare the nanofuels. Sodium dodecyl sulphate (SDS) surfactant was added to improve the stability of these blends. GNPs were characterised using Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR), while the viscosity of nanofuels was investigated by rheometer. UV-spectrometry was used to determine the stability of these nanoplatelets. A ratio of 1:4 GNP: SDS was found to produce maximum stability in biodiesel. Performance and emissions characteristics of these nanofuels have been investigated in a four-stroke compression ignition engine. The maximum reduction in BSFC of 5.05% and the maximum BTE of 22.80% was for B30GNP40DMC10 compared to all other tested blends. A reduction in HC (25%) and CO (4.41%) were observed for B30DMC10, while a reduction in NOx of 3.65% was observed for B30GNP40DMC10. The diesel-biodiesel fuel blends with the addition of GNP exhibited a promising reduction in the average coefficient of friction 15.05%, 8.68% and 3.61% for 120, 80 and 40 ppm concentrations compared to B30. Thus, combined GNP and DMC showed excellent potential for utilisation in diesel engine operation.
  8. Engineered macroalgal and microalgal adsorbents: Synthesis routes and adsorptive performance on hazardous water contaminants
    Lee XJ, Ong HC, Ooi J, Yu KL, Tham TC, Chen WH, et al.
    J Hazard Mater, 2022 Feb 05;423(Pt A):126921.
    PMID: 34523506 DOI: 10.1016/j.jhazmat.2021.126921
    Colourants, micropollutants and heavy metals are regarded as the most notorious hazardous contaminants found in rivers, oceans and sewage treatment plants, with detrimental impacts on human health and environment. In recent development, algal biomass showed great potential for the synthesis of engineered algal adsorbents suitable for the adsorptive management of various pollutants. This review presents comprehensive investigations on the engineered synthesis routes focusing mainly on mechanical, thermochemical and activation processes to produce algal adsorbents. The adsorptive performances of engineered algal adsorbents are assessed in accordance with different categories of hazardous pollutants as well as in terms of their experimental and modelled adsorption capacities. Due to the unique physicochemical properties of macroalgae and microalgae in their adsorbent forms, the adsorption of hazardous pollutants was found to be highly effective, which involved different mechanisms such as physisorption, chemisorption, ion-exchange, complexation and others depending on the types of pollutants. Overall, both macroalgae and microalgae not only can be tailored into different forms of adsorbents based on the applications, their adsorption capacities are also far more superior compared to the conventional adsorbents.
  9. Environment-friendly deoxygenation of non-edible Ceiba oil to liquid hydrocarbon biofuel: process parameters and optimization study
    Abdullah NHB, Mijan NA, Taufiq-Yap YH, Ong HC, Lee HV
    Environ Sci Pollut Res Int, 2022 Jan 25.
    PMID: 35075565 DOI: 10.1007/s11356-022-18508-4
    Non-edible Ceiba oil has the potential to be a sustainable biofuel resource in tropical countries that can replace a portion of today's fossil fuels. Catalytic deoxygenation of the Ceiba oil (high O/C ratio) was conducted to produce hydrocarbon biofuel (high H/C ratio) over NiO-CaO5/SiO2-Al2O3 catalyst with aims of high diesel selectivity and catalyst reusability. In the present study, response surface methodology (RSM) technique with Box-Behnken experimental designs (BBD) was used to evaluate and optimize liquid hydrocarbon yield by considering the following deoxygenation parameters: catalyst loading (1-9 wt. %), reaction temperature (300-380 °C) and reaction time (30-180 min). According to the RSM results, the maximum yield for liquid hydrocarbon n-(C8-C20) was found to be 77% at 340 °C within 105 min and 5 wt. % catalyst loading. In addition, the deoxygenation model showed that the catalyst loading-reaction time interaction has a major impact on the deoxygenation activity. Based on the product analysis, oxygenated species from Ceiba oil were successfully removed in the form of CO2/CO via decarboxylation/decarbonylation (deCOx) pathways. The NiO-CaO5/SiO2-Al2O3 catalyst rendered stable reusability for five consecutive runs with liquid hydrocarbon yield within the range of 66-75% with n-(C15 + C17) selectivity of 64-72%. Despite this, coke deposition was observed after several times of catalyst usage, which is due to the high deoxygenation temperature (> 300 °C) that resulted in unfavourable polymerization side reaction.
  10. Fulltext Establishment of a hospital-based health care workers surveillance programme to keep them safe during the COVID-19 pandemic
    Chong DW, Jayaraj VJ, Rampal S, Said MA, Farid NDN, Zaki RA, et al.
    J Glob Health, 2020 Dec;10(2):0203100.
    PMID: 33304566 DOI: 10.7189/jogh.10.0203100
  11. Extraction of natural astaxanthin from Haematococcus pluvialis using liquid biphasic flotation system
    Khoo KS, Chew KW, Ooi CW, Ong HC, Ling TC, Show PL
    Bioresour Technol, 2019 Oct;290:121794.
    PMID: 31319214 DOI: 10.1016/j.biortech.2019.121794
    This work aimed to study the application of liquid biphasic flotation (LBF) for the efficient and rapid recovery of astaxanthin from H. pluvialis microalgae. The performance of LBF for the extraction of astaxanthin was studied comprehensively under different operating conditions, including types and concentrations of food-grade alcohol and salt, volume ratio, addition of neutral salt, flotation period, and mass of dried H. pluvialis biomass powder. The maximum recovery, extraction efficiency and partition coefficient of astaxanthin obtained from the optimum LBF system were 95.11 ± 1.35%, 99.84 ± 0.05% and 385.16 ± 3.87, respectively. A scaled-up LBF system was also performed, demonstrating the feasibility of extracting natural astaxanthin from microalgae at a larger scale. This exploration of LBF system opens a promising avenue to the extraction of astaxanthin at lower cost and shorter processing time.
  12. Face presentation
    Ong HC, Teo SP
    Med J Malaysia, 1976 Sep;31(1):42-5.
    PMID: 1023012
  13. Fourth generation biofuel from genetically modified algal biomass for bioeconomic development
    Shokravi H, Heidarrezaei M, Shokravi Z, Ong HC, Lau WJ, Din MFM, et al.
    J Biotechnol, 2022 Dec 10;360:23-36.
    PMID: 36272575 DOI: 10.1016/j.jbiotec.2022.10.010
    Biofuels from microalgae have promising potential for a sustainable bioeconomy. Algal strains' oil content and biomass yield are the most influential cost drivers in the fourth generation biofuel (FGB) production. Genetic modification is the key to improving oil accumulation and biomass yield, consequently developing the bioeconomy. This paper discusses current practices, new insights, and emerging trends in genetic modification and their bioeconomic impact on FGB production. It was demonstrated that enhancing the oil and biomass yield could significantly improve the probability of economic success and the net present value of the FGB production process. The techno-economic and socioeconomic burden of using genetically modified (GM) strains and the preventive control strategies on the bioeconomy of FGB production is reviewed. It is shown that the fully lined open raceway pond could cost up to 25% more than unlined ponds. The cost of a plastic hoop air-supported greenhouse covering cultivation ponds is estimated to be US 60,000$ /ha. The competitiveness and profitability of large-scale cultivation of GM biomass are significantly locked to techno-economic and socioeconomic drivers. Nonetheless, it necessitates further research and careful long-term follow-up studies to understand the mechanism that affects these parameters the most.
  14. Fourth generation biofuel from genetically modified algal biomass: Challenges and future directions
    Shokravi H, Shokravi Z, Heidarrezaei M, Ong HC, Rahimian Koloor SS, Petrů M, et al.
    Chemosphere, 2021 Dec;285:131535.
    PMID: 34329137 DOI: 10.1016/j.chemosphere.2021.131535
    Genetic engineering applications in the field of biofuel are rapidly expanding due to their potential to boost biomass productivity while lowering its cost and enhancing its quality. Recently, fourth-generation biofuel (FGB), which is biofuel obtained from genetically modified (GM) algae biomass, has gained considerable attention from academic and industrial communities. However, replacing fossil resources with FGB is still beset with many challenges. Most notably, technical aspects of genetic modification operations need to be more fully articulated and elaborated. However, relatively little attention has been paid to GM algal biomass. There is a limited number of reviews on the progress and challenges faced in the algal genetics of FGB. Therefore, the present review aims to fill this gap in the literature by recapitulating the findings of recent studies and achievements on safe and efficient genetic manipulation in the production of FGB. Then, the essential issues and parameters related to genome editing in algal strains are highlighted. Finally, the main challenges to FGB pertaining to the diffusion risk and regulatory frameworks are addressed. This review concluded that the technical and biosafety aspects of FGB, as well as the complexity and diversity of the related regulations, legitimacy concerns, and health and environmental risks, are among the most important challenges that require a strong commitment at the national/international levels to reach a global consensus.
  15. Fulltext Gender differences and psychological factors associated with suicidal ideation among youth in Malaysia
    Ibrahim N, Amit N, Che Din N, Ong HC
    Psychol Res Behav Manag, 2017;10:129-135.
    PMID: 28496374 DOI: 10.2147/PRBM.S125176
    Suicide is a global phenomenon that has been showing an upward trend in recent years. It is the second leading cause of death among youth. Studies on suicidal ideation warrant greater attention, as it leads to suicide attempts and other health risk behaviors. Thus, the objective of this study was to compare gender differences in suicidal ideation and determine the predictors of suicidal ideation among youth. This cross-sectional study was carried out among 232 youths aged between 15 and 25 years from selected urban areas in Malaysia. The results showed that suicidal ideation was higher among male participants compared with female participants. Age was the predictor of suicidal ideation for males, while depression and loss of motivation, as components of hopelessness, were the predictors of suicidal ideation among females. Hence, it is important that professionals conduct early identification tests for suicidality among young people. This will facilitate the early detection of depression and hopelessness, which is important, in order to prevent suicidal behaviors or other problems before these occur.
  16. Haemoglobin E variants and pregnancy in Malaysian aborigines
    Ong HC
    Acta Haematol., 1974;52(4):220-2.
    PMID: 4217527 DOI: 10.1159/000208244
    Haemoglobin E complicates 22.2°/o of pregnancy in Malaysian aborigines, the prevalence of variants associated with pregnancy being, 15.8% with Hb E trait abnormality, 3.9% with Hb E homozygous disease, and 2.5% with Hb E thalassaemia disease. Minor haematological abnormalities occur with the trait and homozygous conditions, though a more unfavourable response is expected with Hb E thalassaemia. Haemolysis is not a prominent feature and it is suggested that factors other than the haemoglobinopathic state
    probably accounts for any unfavourable response in pregnancy.
    Key Words: Haemoglobin E; Haemoglobinopathies; Haemolytic anaemias; Hb E thalassaemia; Malaysia; Pregnancy
    Study site: Hospital Orang Asli, Gombak, Selangor, Malaysia
  17. Haemoglobin H disease and pregnancy in a Malaysian woman
    Ong HC, White JC, Sinnathuray TA
    Acta Haematol., 1977;58(4):229-33.
    PMID: 410224 DOI: 10.1159/000207832
    A case of haemoglobin H (HbH) disease associated with pregnancy is presented and discussed in the light of reports in the literature. The variable symptomatology is commented upon, although mild to moderate chronic haemolytic anaemia seems to be a constant feature. The roles of folic acid supplements and of splenectomy; the avoidance of oxidant drugs, and the mode of inheritance in HbH disease are briefly commented upon. Available reports indicate that HbH disease probably has no adverse effect on pregnancy. However, the association of the two conditions is uncommon, and reports are too few, therefore, to allow definite conclusions on the outcome in all instances.
  18. Hematological values in pregnancy in Orang Asli (aboriginal) women
    Ong HC
    Med J Malaysia, 1973 Jun;27(4):240-2.
    PMID: 4270778
  19. Fulltext High performance liquid chromatography profiling of health-promoting phytochemicals and evaluation of antioxidant, anti-lipoxygenase, iron chelating and anti-glucosidase activities of wetland macrophytes
    Ooh KF, Ong HC, Wong FC, Sit NW, Chai TT
    Pharmacogn Mag, 2014 Aug;10(Suppl 3):S443-55.
    PMID: 25298659 DOI: 10.4103/0973-1296.139767
    The phytochemistry and bioactivity of wetland macrophytes are underexplored. Plants are known as the natural sources of phytochemical beneficial to health.
  20. Human placental lactogen physiological role in pregnancy
    Ong HC
    Med J Malaysia, 1976 Mar;30(3):165-7.
    PMID: 958050
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