Displaying publications 1 - 20 of 73 in total

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  1. Oxidative torrefaction performance of microalga Nannochloropsis Oceanica towards an upgraded microalgal solid biofuel
    Zhang C, Ho SH, Chen WH, Wang R, Show PL, Ong HC
    J Biotechnol, 2021 Sep 10;338:81-90.
    PMID: 34298023 DOI: 10.1016/j.jbiotec.2021.07.009
    Microalgae are a promising feedstock for carbon-neutral biofuel production due to their superior cellular composition. Alternatively, oxidative torrefaction has been recognized as a potential thermochemical technique for microalgal solid biofuel upgrading. Herein, by using microalga N. oceanica as a feedstock, several characterizations are adopted for evaluating the potential of oxidative torrefaction towards microalgal solid biofuel production. The oxidatively torrefied microalgae can be upgraded as lignite. After in-depth analysis, significant change in the surface microstructure of oxidatively torrefied microalgae is largely changed (via wrinkle and fragmentation) The hydrophobicity, thermal decomposition, thermal stability, and aromatization of oxidatively torrefied microalgae can be largely enhanced as the oxidative torrefaction severity increase. With the increasing torrefaction temperature, the hydrophobicity of oxidative torrefied microalgae gradually improved. The decomposition of C-2/3/5, and -OCH3, the CO bonds of CH3CO-, and the aromatization occurs via oxidative torrefaction according to the NMR analysis. For XPS analysis, torrefaction operation significantly decreases the carbide carbon and enhances the graphitization. As a result, the thermal stability of oxidatively torrefied microalgae is improved. Conclusively, the information obtained in this study can provide insights into the evaluation of oxidative torrefaction performance and fuel properties of microalgal solid biofuel, which may help accelerate the advancement of oxidative torrefaction industrialization.
  2. Recent developments on algal biochar production and characterization
    Yu KL, Lau BF, Show PL, Ong HC, Ling TC, Chen WH, et al.
    Bioresour Technol, 2017 Dec;246:2-11.
    PMID: 28844690 DOI: 10.1016/j.biortech.2017.08.009
    Algal biomass is known as a promising sustainable feedstock for the production of biofuels and other valuable products. However, since last decade, massive amount of interests have turned to converting algal biomass into biochar. Due to their high nutrient content and ion-exchange capacity, algal biochars can be used as soil amendment for agriculture purposes or adsorbents in wastewater treatment for the removal of organic or inorganic pollutants. This review describes the conventional (e.g., slow and microwave-assisted pyrolysis) and newly developed (e.g., hydrothermal carbonization and torrefaction) methods used for the synthesis of algae-based biochars. The characterization of algal biochar and a comparison between algal biochar with biochar produced from other feedstocks are also presented. This review aims to provide updated information on the development of algal biochar in terms of the production methods and the characterization of its physical and chemical properties to justify and to expand their potential applications.
  3. Investigation of antibacterial mechanism and identification of bacterial protein targets mediated by antibacterial medicinal plant extracts
    Yong AL, Ooh KF, Ong HC, Chai TT, Wong FC
    Food Chem, 2015 Nov 1;186:32-6.
    PMID: 25976788 DOI: 10.1016/j.foodchem.2014.11.103
    In this paper, we investigated the antibacterial mechanism and potential therapeutic targets of three antibacterial medicinal plants. Upon treatment with the plant extracts, bacterial proteins were extracted and resolved using denaturing gel electrophoresis. Differentially-expressed bacterial proteins were excised from the gels and subjected to sequence analysis by MALDI TOF-TOF mass spectrometry. From our study, seven differentially expressed bacterial proteins (triacylglycerol lipase, N-acetylmuramoyl-L-alanine amidase, flagellin, outer membrane protein A, stringent starvation protein A, 30S ribosomal protein s1 and 60 kDa chaperonin) were identified. Additionally, scanning electron microscope study indicated morphological damages induced on bacterial cell surfaces. To the best of our knowledge, this represents the first time these bacterial proteins are being reported, following treatments with the antibacterial plant extracts. Further studies in this direction could lead to the detailed understanding of their inhibition mechanism and discovery of target-specific antibacterial agents.
  4. Fulltext Antioxidant, Metal Chelating, Anti-glucosidase Activities and Phytochemical Analysis of Selected Tropical Medicinal Plants
    Wong FC, Yong AL, Ting EP, Khoo SC, Ong HC, Chai TT
    Iran J Pharm Res, 2014;13(4):1409-15.
    PMID: 25587331
    The purpose of this investigation was to determine the antioxidant potentials and anti-glucosidase activities of six tropical medicinal plants. The levels of phenolic constituents in these medicinal plants were also quantified and compared. Antioxidation potentials were determined colorimetrically for scavenging activities against DPPH and NO radicals. Metal chelating assay was based on the measurement of iron-ferrozine absorbance at 562 nm. Anti-diabetic potentials were measured by using α-glucosidase as target enzyme. Medicinal plants' total phenolic, total flavonoid and hydroxycinnamic acid contents were determined using spectrophotometric methods, by comparison to standard plots prepared using gallic acid, quercetin and caffeic acid standards, respectively. Radical scavenging and metal chelating activities were detected in all medicinal plants, in concentration-dependent manners. Among the six plants tested, C. nutans, C. formosana and H. diffusa were found to possess α-glucosidase inhibitory activities. Spectrophotometric analysis indicated that the total phenolic, total flavonoid and hydroxycinnamic acid contents ranged from 12.13-21.39 mg GAE per g of dry sample, 1.83-9.86 mg QE per g of dry sample, and 0.91-2.74 mg CAE per g of dry sample, respectively. Our results suggested that C. nutans and C. formosana could potentially be used for the isolation of potent antioxidants and anti-diabetic compounds. To the best of our knowledge, this study represents the first time that C. nutans (Acanthaceae family) was reported in literature with glucosidase inhibition activity.
  5. Novel bufferless photosynthetic microbial fuel cell (PMFCs) for enhanced electrochemical performance
    Wang CT, Huang YS, Sangeetha T, Chen YM, Chong WT, Ong HC, et al.
    Bioresour Technol, 2018 May;255:83-87.
    PMID: 29414177 DOI: 10.1016/j.biortech.2018.01.086
    Photosynthetic microbial fuel cells (PMFCs) are novel bioelectrochemical transducers that employ microalgae to generate oxygen, organic metabolites and electrons. Conventional PMFCs employ non-eco-friendly membranes, catalysts and phosphate buffer solution. Eliminating the membrane, buffer and catalyst can make the MFC a practical possibility. Therefore, single chambered (SPMFC) were constructed and operated at different recirculation flow rates (0, 40 and 240 ml/min) under bufferless conditions. Furthermore, maximum power density of 4.06 mW/m2, current density of 46.34 mA/m2 and open circuit potential of 0.43 V and low internal resistance of 611.8 Ω were obtained at 40 ml/min. Based on the results it was decided that SPMFC was better for operation at 40 ml/min. Therefore, these findings provided progressive insights for future pilot and industrial scale studies of PMFCs.
  6. Fulltext Rapid Ultrasound-Assisted Starch Extraction from Sago Pith Waste (SPW) for the Fabrication of Sustainable Bioplastic Film
    Tan SX, Andriyana A, Lim S, Ong HC, Pang YL, Ngoh GC
    Polymers (Basel), 2021 Dec 15;13(24).
    PMID: 34960953 DOI: 10.3390/polym13244398
    The present study was conducted to optimize the extraction yield of starch from sago (Metroxylon sagu) pith waste (SPW) with the assistance of ultrasound ensued by the transformation of extracted starch into a higher value-added bioplastic film. Sago starch with extraction yield of 71.4% was successfully obtained using the ultrasound-assisted extraction, with the following conditions: particle size <250 µm, solid loading of 10 wt.%, ultrasonic amplitude of 70% and duty cycle of 83% in 5 min. The rapid ultrasound approach was proven to be more effective than the conventional extraction with 60.9% extraction yield in 30 min. Ultrasound-extracted starch was found to exhibit higher starch purity than the control starch as indicated by the presence of lower protein and ash contents. The starch granules were found to have irregular and disrupted surfaces after ultrasonication. The disrupted starch granules reduced the particle size and increased the swelling power of starch which was beneficial in producing a film-forming solution. The ultrasound-extracted sago starch was subsequently used to prepare a bioplastic film via solution casting method. A brownish bioplastic film with tensile strength of 0.9 ± 0.1 MPa, Young's modulus of 22 ± 0.8 MPa, elongation at break of 13.6 ± 2.0% and water vapour permeability (WVP) of 1.11 ± 0.1 × 10-8 g m-1 s-1 Pa-1 was obtained, suggesting its feasibility as bioplastic material. These findings provide a means of utilization for SPW which is in line with the contemporary trend towards greener and sustainable products and processes.
  7. Fulltext Characterization and Parametric Study on Mechanical Properties Enhancement in Biodegradable Chitosan-Reinforced Starch-Based Bioplastic Film
    Tan SX, Ong HC, Andriyana A, Lim S, Pang YL, Kusumo F, et al.
    Polymers (Basel), 2022 Jan 11;14(2).
    PMID: 35054685 DOI: 10.3390/polym14020278
    Bioplastic has been perceived as a promising candidate to replace petroleum-based plastics due to its environment-friendly and biodegradable characteristics. This study presents the chitosan reinforced starch-based bioplastic film prepared by the solution casting and evaporation method. The effects of processing parameters, i.e., starch concentration, glycerol loading, process temperature and chitosan loading on mechanical properties were examined. Optimum tensile strength of 5.19 MPa and elongation at break of 44.6% were obtained under the combined reaction conditions of 5 wt.% starch concentration, 40 wt.% glycerol loading, 20 wt.% chitosan loading and at a process temperature of 70 °C. From the artificial neural network (ANN) modeling, the coefficient of determination (R2) for tensile strength and elongation at break were found to be 0.9955 and 0.9859, respectively, which proved the model had good fit with the experimental data. Interaction and miscibility between starch and chitosan were proven through the peaks shifting to a lower wavenumber in FTIR and a reduction of crystallinity in XRD. TGA results suggested the chitosan-reinforced starch-based bioplastic possessed reasonable thermal stability under 290 °C. Enhancement in water resistance of chitosan-incorporated starch-based bioplastic film was evidenced with a water uptake of 251% as compared to a 302% registered by the pure starch-based bioplastic film. In addition, the fact that the chitosan-reinforced starch-based bioplastic film degraded to 52.1% of its initial weight after 28 days suggests it is a more sustainable alternative than the petroleum-based plastics.
  8. Identification of Potential Anticancer Protein Targets in Cytotoxicity Mediated by Tropical Medicinal Fern Extracts
    Tan ST, Ong HC, Chai TT, Wong FC
    Pharmacogn Mag, 2018 04 10;14(54):227-230.
    PMID: 29720836 DOI: 10.4103/pm.pm_282_17
    Background: Medicinal fern species represent a potentially important source for both food and medicinal applications. Previously, two underutilized tropical fern species (Blechnum orientale and Phymatopteris triloba) were reported with cytotoxic activities against selected cancer cell lines. However, the exact mechanism remains elusive.

    Objective: In this paper, we reported the identification of six differentially expressed proteins isolated from cancer cells, following exposure to the cytotoxic fern extracts.

    Materials and Methods: The identities of these cancer proteins were determined by matrix-assisted laser desorption ionization time-of-flight protein sequencing.

    Results: The cancer proteins were identified as follows: elongation factor 1-γ, glyceraldehydes-3-phosphate dehydrogenase, heat shock protein 90-β, heterogeneous nuclear ribonucleoprotein-A2/B1, truncated nucleolar phosphoprotein B23, and tubulin-β chain. To the best of our knowledge, this paper represents the first time these cancer proteins are being reported, following exposure to the aforementioned cytotoxic fern extracts.

    Conclusion: It is hoped that further efforts in this direction could lead to the identification and development of target-specific chemotherapeutic agents.

    SUMMARY: Cytotoxic fern extracts were tested in anti-cancer proteomic works.Six differentially-expressed cancer proteins were identified.Potential anti-cancer protein targets were reported. Abbreviations used: EF: Elongation factor; HRP: Horseradish peroxidase; HSP: Heat shock protein; MALDI: Matrix-assisted laser desorption/ionization.

  9. 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.
  10. Pyrolysis of waste oils for the production of biofuels: A critical review
    Su G, Ong HC, Mofijur M, Mahlia TMI, Ok YS
    J Hazard Mater, 2022 Feb 15;424(Pt B):127396.
    PMID: 34673394 DOI: 10.1016/j.jhazmat.2021.127396
    The application of waste oils as pyrolysis feedstocks to produce high-grade biofuels is receiving extensive attention, which will diversify energy supplies and address environmental challenges caused by waste oils treatment and fossil fuel combustion. Waste oils are the optimal raw materials to produce biofuels due to their high hydrogen and volatile matter content. However, traditional disposal methods such as gasification, transesterification, hydrotreating, solvent extraction, and membrane technology are difficult to achieve satisfactory effects owing to shortcomings like enormous energy demand, long process time, high operational cost, and hazardous material pollution. The usage of clean and safe pyrolysis technology can break through the current predicament. The bio-oil produced by the conventional pyrolysis of waste oils has a high yield and HHV with great potential to replace fossil fuel, but contains a high acid value of about 120 mg KOH/g. Nevertheless, the application of CaO and NaOH can significantly decrease the acid value of bio-oil to close to zero. Additionally, the addition of coexisting bifunctional catalyst, SBA-15@MgO@Zn in particular, can simultaneously reduce the acid value and positively influence the yield and quality of bio-oil. Moreover, co-pyrolysis with plastic waste can effectively save energy and time, and improve bio-oil yield and quality. Consequently, this paper presents a critical and comprehensive review of the production of biofuels using conventional and advanced pyrolysis of waste oils.
  11. State-of-the-art of the pyrolysis and co-pyrolysis of food waste: Progress and challenges
    Su G, Ong HC, Fattah IMR, Ok YS, Jang JH, Wang CT
    Sci Total Environ, 2022 Feb 25;809:151170.
    PMID: 34699825 DOI: 10.1016/j.scitotenv.2021.151170
    The continuous growth of population and the steady improvement of people's living standards have accelerated the generation of massive food waste. Untreated food waste has great potential to harm the environment and human health due to bad odor release, bacterial leaching, and virus transmission. However, the application of traditional disposal techniques like composting, landfilling, animal feeding, and anaerobic digestion are difficult to ease the environmental burdens because of problems such as large land occupation, virus transmission, hazardous gas emissions, and poor efficiency. Pyrolysis is a practical and promising route to reduce the environmental burden by converting food waste into bioenergy. This paper aims to analyze the characteristics of food waste, introduce the production of biofuels from conventional and advanced pyrolysis of food waste, and provide a basis for scientific disposal and sustainable management of food waste. The review shows that co-pyrolysis and catalytic pyrolysis significantly impact the pyrolysis process and product characteristics. The addition of tire waste promotes the synthesis of hydrocarbons and inhibits the formation of oxygenated compounds efficiently. The application of calcium oxide (CaO) exhibits good performance in the increment of bio-oil yield and hydrocarbon content. Based on this literature review, pyrolysis can be considered as the optimal technique for dealing with food waste and producing valuable products.
  12. Fulltext Valorisation of medical waste through pyrolysis for a cleaner environment: Progress and challenges
    Su G, Ong HC, Ibrahim S, Fattah IMR, Mofijur M, Chong CT
    Environ Pollut, 2021 Jun 15;279:116934.
    PMID: 33744627 DOI: 10.1016/j.envpol.2021.116934
    The COVID-19 pandemic has exerted great shocks and challenges to the environment, society and economy. Simultaneously, an intractable issue appeared: a considerable number of hazardous medical wastes have been generated from the hospitals, clinics, and other health care facilities, constituting a serious threat to public health and environmental sustainability without proper management. Traditional disposal methods like incineration, landfill and autoclaving are unable to reduce environmental burden due to the issues such as toxic gas release, large land occupation, and unsustainability. While the application of clean and safe pyrolysis technology on the medical wastes treatment to produce high-grade bioproducts has the potential to alleviate the situation. Besides, medical wastes are excellent and ideal raw materials, which possess high hydrogen, carbon content and heating value. Consequently, pyrolysis of medical wastes can deal with wastes and generate valuable products like bio-oil and biochar. Consequently, this paper presents a critical and comprehensive review of the pyrolysis of medical wastes. It demonstrates the feasibility of pyrolysis, which mainly includes pyrolysis characteristics, product properties, related problems, the prospects and future challenges of pyrolysis of medical wastes.
  13. 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.
  14. Perspectives on cultivation and harvesting technologies of microalgae, towards environmental sustainability and life cycle analysis
    Soudagar MEM, Kiong TS, Jathar L, Nik Ghazali NN, Ramesh S, Awasarmol U, et al.
    Chemosphere, 2024 Apr;353:141540.
    PMID: 38423144 DOI: 10.1016/j.chemosphere.2024.141540
    The development of algae is seen as a potential and ecologically sound approach to address the increasing demands in multiple sectors. However, successful implementation of processes is highly dependent on effective growing and harvesting methods. The present study provides a complete examination of contemporary techniques employed in the production and harvesting of algae, with a particular emphasis on their sustainability. The review begins by examining several culture strategies, encompassing open ponds, closed photobioreactors, and raceway ponds. The analysis of each method is conducted in a systematic manner, with a particular focus on highlighting their advantages, limitations, and potential for expansion. This approach ensures that the conversation is in line with the objectives of sustainability. Moreover, this study explores essential elements of algae harvesting, including the processes of cell separation, dewatering, and biomass extraction. Traditional methods such as centrifugation, filtration, and sedimentation are examined in conjunction with novel, environmentally concerned strategies including flocculation, electro-coagulation, and membrane filtration. It evaluates the impacts on the environment that are caused by the cultivation process, including the usage of water and land, the use of energy, the production of carbon dioxide, and the runoff of nutrients. Furthermore, this study presents a thorough examination of the current body of research pertaining to Life Cycle Analysis (LCA) studies, presenting a perspective that emphasizes sustainability in the context of algae harvesting systems. In conclusion, the analysis ends up with an examination ahead at potential areas for future study in the cultivation and harvesting of algae. This review is an essential guide for scientists, policymakers, and industry experts associated with the advancement and implementation of algae-based technologies.
  15. In vitro antidermatophytic activity and cytotoxicity of extracts derived from medicinal plants and marine algae
    Sit NW, Chan YS, Lai SC, Lim LN, Looi GT, Tay PL, et al.
    J Mycol Med, 2018 Sep;28(3):561-567.
    PMID: 30060991 DOI: 10.1016/j.mycmed.2018.07.001
    OBJECTIVES: This study was conducted to evaluate the antidermatophytic activity of 48 extracts obtained from medicinal plants (Cibotium barometz, Melastoma malabathricum, Meuhlenbeckia platyclada, Rhapis excelsa, Syzygium myrtifolium, Vernonia amygdalina) and marine algae (Caulerpa sertularioides, Kappaphycus alvarezii) against Trichophyton rubrum and Trichophyton interdigitale (ATCC reference strains), and the cytotoxicity using African monkey kidney epithelial (Vero) cells. Active plant extracts were screened for the presence of phytochemicals and tested against clinical isolates of Trichophyton tonsurans.

    METHODS: Six different extracts (hexane, chloroform, ethyl acetate, ethanol, methanol and water) were obtained from each plant or algae sample using sequential solvent extraction. The antidermatophytic activity for the extracts was assessed using a colourimetric broth microdilution method. The viability of Vero cells was measured by Neutral Red uptake assay.

    RESULTS: All the extracts (except the water extracts of V. amygdalina, C. sertularioides and K. alvarezii) showed antidermatophytic activity against Trichophyton spp. The minimum fungicidal concentration (MFC) ranges for the plant extracts against T. rubrum and T. interdigitale are 0.0025-2.50 and 0.005-2.50mg/mL, respectively. The algae extracts exhibited lower potency against both species, showing MFC ranges of 0.08-2.50 and 0.31-2.50mg/mL, respectively. The ethanol and methanol extracts from the leaves of R. excelsa, and the methanol and water extracts from the leaves of S. myrtifolium were highly active (MFC<0.1mg/mL) and with high selectivity indices (SI>2.8) against reference strains of T. rubrum and T. interdigitale, and most of the clinical isolates of T. tonsurans. Phytochemical analysis indicates the presence of alkaloids, anthraquinones, flavonoids, saponins, tannins, phenolics and triterpenoids in the extracts.

    CONCLUSIONS: The medicinal plant extracts exhibited stronger antidermatophytic activity compared to the algae extracts. The leaves of R. excelsa and S. myrtifolium are potential sources of new antidermatophytic agents against Trichophyton spp.

  16. Analysis of the performance, emission and combustion characteristics of a turbocharged diesel engine fuelled with Jatropha curcas biodiesel-diesel blends using kernel-based extreme learning machine
    Silitonga AS, Hassan MH, Ong HC, Kusumo F
    Environ Sci Pollut Res Int, 2017 Nov;24(32):25383-25405.
    PMID: 28932948 DOI: 10.1007/s11356-017-0141-9
    The purpose of this study is to investigate the performance, emission and combustion characteristics of a four-cylinder common-rail turbocharged diesel engine fuelled with Jatropha curcas biodiesel-diesel blends. A kernel-based extreme learning machine (KELM) model is developed in this study using MATLAB software in order to predict the performance, combustion and emission characteristics of the engine. To acquire the data for training and testing the KELM model, the engine speed was selected as the input parameter, whereas the performance, exhaust emissions and combustion characteristics were chosen as the output parameters of the KELM model. The performance, emissions and combustion characteristics predicted by the KELM model were validated by comparing the predicted data with the experimental data. The results show that the coefficient of determination of the parameters is within a range of 0.9805-0.9991 for both the KELM model and the experimental data. The mean absolute percentage error is within a range of 0.1259-2.3838. This study shows that KELM modelling is a useful technique in biodiesel production since it facilitates scientists and researchers to predict the performance, exhaust emissions and combustion characteristics of internal combustion engines with high accuracy.
  17. 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.
  18. 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.
  19. 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.
  20. 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 

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