Displaying publications 41 - 60 of 87 in total

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  1. Leong YK, Lan JC, Loh HS, Ling TC, Ooi CW, Show PL
    J Biosci Bioeng, 2017 Mar;123(3):370-375.
    PMID: 27745851 DOI: 10.1016/j.jbiosc.2016.09.007
    Polyhydroxyalkanoates (PHAs), a class of renewable and biodegradable green polymers, have gained attraction as a potential substitute for the conventional plastics due to the increasing concern towards environmental pollution as well as the rapidly depleting petroleum reserve. Nevertheless, the high cost of downstream processing of PHA has been a bottleneck for the wide adoption of PHAs. Among the options of PHAs recovery techniques, aqueous two-phase extraction (ATPE) outshines the others by having the advantages of providing a mild environment for bioseparation, being green and non-toxic, the capability to handle a large operating volume and easily scaled-up. Utilizing unique properties of thermo-responsive polymer which has decreasing solubility in its aqueous solution as the temperature rises, cloud point extraction (CPE) is an ATPE technique that allows its phase-forming component to be recycled and reused. A thorough literature review has shown that this is the first time isolation and recovery of PHAs from Cupriavidus necator H16 via CPE was reported. The optimum condition for PHAs extraction (recovery yield of 94.8% and purification factor of 1.42 fold) was achieved under the conditions of 20 wt/wt % ethylene oxide-propylene oxide (EOPO) with molecular weight of 3900 g/mol and 10 mM of sodium chloride addition at thermoseparating temperature of 60°C with crude feedstock limit of 37.5 wt/wt %. Recycling and reutilization of EOPO 3900 can be done at least twice with satisfying yield and PF. CPE has been demonstrated as an effective technique for the extraction of PHAs from microbial crude culture.
  2. Show PL, Tang MS, Nagarajan D, Ling TC, Ooi CW, Chang JS
    Int J Mol Sci, 2017 Jan 22;18(1).
    PMID: 28117737 DOI: 10.3390/ijms18010215
    Microalgae contribute up to 60% of the oxygen content in the Earth's atmosphere by absorbing carbon dioxide and releasing oxygen during photosynthesis. Microalgae are abundantly available in the natural environment, thanks to their ability to survive and grow rapidly under harsh and inhospitable conditions. Microalgal cultivation is environmentally friendly because the microalgal biomass can be utilized for the productions of biofuels, food and feed supplements, pharmaceuticals, nutraceuticals, and cosmetics. The cultivation of microalgal also can complement approaches like carbon dioxide sequestration and bioremediation of wastewaters, thereby addressing the serious environmental concerns. This review focuses on the factors affecting microalgal cultures, techniques adapted to obtain high-density microalgal cultures in photobioreactors, and the conversion of microalgal biomass into biofuels. The applications of microalgae in carbon dioxide sequestration and phycoremediation of wastewater are also discussed.
  3. Sankaran R, Manickam S, Yap YJ, Ling TC, Chang JS, Show PL
    Ultrason Sonochem, 2018 Nov;48:231-239.
    PMID: 30080546 DOI: 10.1016/j.ultsonch.2018.06.002
    In this study, a simple sugaring-out supported by liquid biphasic flotation technique combined with ultrasonication was introduced for the extraction of proteins from microalgae. Sugaring-out as a phase separation method is novel and has been used in the extraction of metal ions, biomolecules and drugs. But, its functioning in protein separation from microalgae is still unknown. In this work, the feasibility of sugaring-out coupled with ultrasound for the extraction of protein was investigated. Primary studies were carried out to examine the effect of sonication on the microalgae cell as well as the separation efficiency of the integrated method. Effect of various operating parameters such as the concentration of microalgae biomass, the location of sonication probe, sonication time, ultrasonic pulse mode (includes varying ON and OFF duration of sonication), concentration of glucose, types of sugar, concentration of acetonitrile and the flow rate in the flotation system for achieving a higher separation efficiency and yield of protein were assessed. Besides, a large-scale study of the integration method was conducted to verify the consistency of the followed technique. A maximum efficiency (86.38%) and yield (93.33%) were attained at the following optimized conditions: 0.6% biomass concentration, 200 g/L of glucose concentration, 100% acetonitrile concentration with 5 min of 5 s ON/10 s OFF pulse mode and at a flow rate of 100 cc/min. The results obtained for large scale were 85.25% and 92.24% for efficiency and yield respectively. The proposed liquid biphasic flotation assisted with ultrasound for protein separation employing sugaring-out demonstrates a high production and separation efficiency and is a cost-effective solution. More importantly, this method provides the possibility of extending its application for the extraction of other important biomolecules.
  4. Sankaran R, Parra Cruz RA, Pakalapati H, Show PL, Ling TC, Chen WH, et al.
    Bioresour Technol, 2020 Feb;298:122476.
    PMID: 31810736 DOI: 10.1016/j.biortech.2019.122476
    Microalgal and lignocellulosic biomass is the most sumptuous renewable bioresource raw material existing on earth. Recently, the bioconversion of biomass into biofuels have received significant attention replacing fossil fuels. Pretreatment of biomass is a critical process in the conversion due to the nature and structure of the biomass cell wall that is complex. Although green technologies for biofuel production are advancing, the productivity and yield from these techniques are low. Over the past years, various pretreatment techniques have been developed and successfully employed to improve the technology. This paper presents an in-depth review of the recent advancement of pretreatment methods focusing on microalgal and lignocellulosic biomass. The technological approaches involving physical, chemical, biological and other latest pretreatment methods are reviewed.
  5. Yew GY, Chew KW, Malek MA, Ho YC, Chen WH, Ling TC, et al.
    Biotechnol Biofuels, 2019;12:252.
    PMID: 31666807 DOI: 10.1186/s13068-019-1591-8
    Background: The extraction of lipids from microalgae requires a pretreatment process to break the cell wall and subsequent extraction processes to obtain the lipids for biofuels production. The multistep operation tends to incur high costs and are energy intensive due to longer process operations. This research work applies the combination of radicals from hydrogen peroxide with an organic solvent as a chemical pretreatment method for disrupting the cell wall of microalgae and simultaneously extracting lipids from the biomass in a one-step biphasic solution.

    Result: Several parameters which can affect the biphasic system were analyzed: contact time, volume of solvent, volume ratio, type of organic solvent, biomass amount and concentration of solvents, to extract the highest amount of lipids from microalgae. The results were optimized and up to 83.5% of lipid recovery yield and 94.6% of enhancement was successfully achieved. The results obtain from GC-FID were similar to the analysis of triglyceride lipid standard.

    Conclusion: The profound hybrid biphasic system shows great potential to radically disrupt the cell wall of microalgae and instantaneously extract lipids in a single-step approach. The lipids extracted were tested to for its comparability to biodiesel performance.

  6. Show PL, Pal P, Leong HY, Juan JC, Ling TC
    Environ Monit Assess, 2019 Mar 18;191(4):227.
    PMID: 30887225 DOI: 10.1007/s10661-019-7380-9
    Landfill application is the most common approach for biowaste treatment via leachate treatment system. When municipal solid waste deposited in the landfills, microbial decomposition breaks down the wastes generating the end products, such as carbon dioxide, methane, volatile organic compounds, and liquid leachate. However, due to the landfill age, the fluctuation in the characteristics of landfill leachate is foreseen in the leachate treatment plant. The focuses of the researchers are keeping leachate from contaminating groundwater besides keeping potent methane emissions from reaching the atmosphere. To address the above issues, scientists are required to adopt green biological methods to keep the environment safe. This review focuses on the assorting of research papers on organic content and nitrogen removal from the leachate via recent effective biological technologies instead of conventional nitrification and denitrification process. The published researches on the characteristics of various Malaysian landfill sites were also discussed. The understanding of the mechanism behind the nitrification and denitrification process will help to select an optimized and effective biological treatment option in treating the leachate waste. Recently, widely studied technologies for the biological treatment process are aerobic methane oxidation coupled to denitrification (AME-D) and partial nitritation-anammox (PN/A) process, and both were discussed in this review article. This paper gives the idea of the modification of the conventional treatment technologies, such as combining the present processes to make the treatment process more effective. With the integration of biological process in the leachate treatment, the effluent discharge could be treated in shortcut and novel pathways, and it can lead to achieving "3Rs" of reduce, reuse, and recycle approach.
  7. Khoo KS, Lee SY, Ooi CW, Fu X, Miao X, Ling TC, et al.
    Bioresour Technol, 2019 Sep;288:121606.
    PMID: 31178260 DOI: 10.1016/j.biortech.2019.121606
    Haematococcus pluvialis is one of the most abundant sources of natural astaxanthin as compared to others microorganism. Therefore, it is important to understand the biorefinery of astaxanthin from H. pluvialis, starting from the cultivation stage to the downstream processing of astaxanthin. The present review begins with an introduction of cellular morphologies and life cycle of H. pluvialis from green vegetative motile stage to red non-motile haematocyst stage. Subsequently, the conventional biorefinery methods (e.g., mechanical disruption, solvent extraction, direct extraction using vegetable oils, and enhanced solvent extraction) and recent advanced biorefinery techniques (e.g., supercritical CO2 extraction, magnetic-assisted extraction, ionic liquids extraction, and supramolecular solvent extraction) were presented and evaluated. Moreover, future prospect and challenges were highlighted to provide a useful guide for future development of biorefinery of astaxanthin from H. pluvialis. The review aims to serve as a present knowledge for researchers dealing with the bioproduction of astaxanthin from H. pluvialis.
  8. Cheng SY, Show PL, Juan JC, Ling TC, Lau BF, Lai SH, et al.
    Environ Res, 2020 09;188:109737.
    PMID: 32554270 DOI: 10.1016/j.envres.2020.109737
    Sustainable wastewater treatment necessitates the application of natural and green material in the approach. Thus, selecting a natural coagulant in leachate treatment is a crucial step in landfill operation to prevent secondary environmental pollution due to residual inorganic coagulant in treated effluent. Current study investigated the application of guar gum in landfill leachate treatment. Central composite design in response surface methodology was used to optimize the performance of Chemical Oxygen Demand (COD) removal. Quadratic model developed indicated the optimum COD removal 22.57% at guar gum dosage of 44.39 mg/L, pH 8.56 (natural pH of leachate) and mixing speed 79.27 rpm. Scanning electron microscopy showed that floc was compact and energy-dispersive-x-ray analysis showed that guar gum was capable to adsorb multiple ions from the leachate. Structural characterization using Fourier Transform Infrared analysis demonstrated that hydrogen bonding between guar and pollutant particles was involved in coagulation and flocculation process. Therefore, guar gum coagulant present potential to be an alternative in leachate treatment where pH requirement is not required during treatment. Simultaneously, adsorption by guar gum offers added pollutant removal advantage.
  9. Chan SS, Khoo KS, Chew KW, Ling TC, Show PL
    Bioresour Technol, 2022 Jan;344(Pt A):126159.
    PMID: 34673198 DOI: 10.1016/j.biortech.2021.126159
    The litter of persistent organic pollutants (POPs) into the water streams and soil bodies via industrial effluents led to several adverse effects on the environment, health, and ecosystem. For the past decades, scientists have been paying efforts in the innovation and development of POPs removal from wastewater treatment. However, the conventional methods used for the removal of POPs from wastewater are costly and could lead to secondary pollution including soil and water bodies pollution. In recent, the utilization of green mechanisms such as biosorption, bioaccumulation and biodegradation has drawn attention and prelude the potential of green technology globally. Microalgae-bacteria consortia have emerged to be one of the latent wastewater treatment systems. The synergistic interactions between microalgae and bacteria could proficiently enhance the existing biological wastewater treatment system. This paper will critically review the comparison of conventional and recent advanced wastewater treatment systems and the mechanisms of the microalgae-bacteria symbiosis system.
  10. Zhuang D, He N, Khoo KS, Ng EP, Chew KW, Ling TC
    Chemosphere, 2022 Mar;291(Pt 2):132932.
    PMID: 34798100 DOI: 10.1016/j.chemosphere.2021.132932
    Microalgae is an autotrophic organism with fast growth, short reproduction cycle, and strong environmental adaptability. In recent years, microalgae and the bioactive ingredients extracted from microalgae are regarded as potential substitutes for raw materials in the pharmaceutical and the cosmetics industry. In this review, the characteristics and efficacy of the high-value components of microalgae are discussed in detail, along with the sources and extraction technologies of algae used to obtain high-value ingredients are reviewed. Moreover, the latest trends in biotherapy based on high-value algae extracts as materials are discussed. The excellent antioxidant properties of microalgae derivatives are regarded as an attractive replacement for safe and environmentally friendly cosmetics formulation and production. Through further studies, the mechanism of microalgae bioactive compounds can be understood better and reasonable clinical trials conducted can safely conclude the compliance of microalgae-derived drugs or cosmetics to be necessary standards to be marketed.
  11. Zhao X, Lim SK, Tan CS, Li B, Ling TC, Huang R, et al.
    Materials (Basel), 2015 Jan 30;8(2):462-473.
    PMID: 28787950 DOI: 10.3390/ma8020462
    Foamed mortar with a density of 1300 kg/m³ was prepared. In the initial laboratory trials, water-to-cement (w/c) ratios ranging from 0.54 to 0.64 were tested to determine the optimal value for foamed mortar corresponding to the highest compressive strength without compromising its fresh state properties. With the obtained optimal w/c ratio of 0.56, two types of foamed mortar were prepared, namely cement-foamed mortar (CFM) and slag-foamed mortar (SFM, 50% cement was replaced by slag weight). Four different curing conditions were adopted for both types of foamed mortar to assess their compressive strength, ultrasonic pulse velocity (UPV) and thermal insulation performance. The test results indicated that utilizing 50% of slag as cement replacement in the production of foamed mortar improved the compressive strength, UPV and thermal insulation properties. Additionally, the initial water curing of seven days gained higher compressive strength and increased UPV values as compared to the air cured and natural weather curing samples. However, this positive effect was more pronounced in the case of compressive strength than in the UPV and thermal conductivity of foamed mortar.
  12. Sankaran R, Show PL, Lee SY, Yap YJ, Ling TC
    Bioresour Technol, 2018 Feb;250:306-316.
    PMID: 29174909 DOI: 10.1016/j.biortech.2017.11.050
    Liquid Biphasic Flotation (LBF) is an advanced recovery method that has been effectively applied for biomolecules extraction. The objective of this investigation is to incorporate the fermentation and extraction process of lipase from Burkholderia cepacia using flotation system. Initial study was conducted to compare the performance of bacteria growth and lipase production using flotation and shaker system. From the results obtained, bacteria shows quicker growth and high lipase yield via flotation system. Integration process for lipase separation was investigated and the result showed high efficiency reaching 92.29% and yield of 95.73%. Upscaling of the flotation system exhibited consistent result with the lab-scale which are 89.53% efficiency and 93.82% yield. The combination of upstream and downstream processes in a single system enables the acceleration of product formation, improves the product yield and facilitates downstream processing. This integration system demonstrated its potential for biomolecules fermentation and separation that possibly open new opportunities for industrial production.
  13. Chia SR, Chew KW, Show PL, Yap YJ, Ong HC, Ling TC, et al.
    Biotechnol J, 2018 Jun;13(6):e1700618.
    PMID: 29356369 DOI: 10.1002/biot.201700618
    Microalgae are considered promising feedstock for the production of biofuels and other bioactive compounds, yet there are still challenges on commercial applications of microalgae-based products. This review focuses on the economic analysis, environmental impact, and industrial potential of biofuels production from microalgae. The cost of biofuels production remains higher compared to conventional fuel sources. However, integration of biorefinery pathways with biofuels production for the recovery of value-added products (such as antioxidants, natural dyes, cosmetics, nutritional supplements, polyunsaturated fatty acids, and so forth) could substantially reduce the production costs. It also paves the way for sustainable energy resources by significantly reducing the emissions of CO2 , NOx , SOx , and heavy metals. Large-scale biofuels production has yet to be successfully commercialized with many roadblocks ahead and heavy competition with conventional fuel feedstock as well as technological aspects. One of the prominent challenges is to develop a cost-effective method to achieve high-density microalgal cultivation on an industrial scale. The biofuels industry should be boosted by Government's support in the form of subsidies and incentives, for addressing the pressing climate change issues, achieving sustainability, and energy security.
  14. Chong FC, Tan WS, Biak DR, Ling TC, Tey BT
    J Chromatogr B Analyt Technol Biomed Life Sci, 2009 May 15;877(14-15):1561-7.
    PMID: 19395325 DOI: 10.1016/j.jchromb.2009.03.048
    Nucleocapsid (N) protein of Nipah virus (NiV) is a potential serological marker used in the diagnosis of NiV infections. In this study, a rapid and efficient purification system, HisTrap 6 Fast Flow packed bed column was applied to purify recombinant histidine-tagged N protein of NiV from clarified feedstock. The optimizations of binding and elution conditions of N protein of NiV onto and from Nickel Sepharose 6 Fast Flow were investigated. The optimal binding was achieved at pH 7.5, superficial velocity of 1.25 cm/min. The bound N protein was successfully recovered by a stepwise elution with different concentration of imidazole (50, 150, 300 and 500 mM). The N protein of NiV was captured and eluted from an inlet N protein concentration of 0.4 mg/ml in a scale-up immobilized metal affinity chromatography (IMAC) packed bed column of Nickel Sepharose 6 Fast Flow with the optimized condition obtained from the method scouting. The purification of histidine-tagged N protein using IMAC packed bed column has resulted a 68.3% yield and a purification factor of 7.94.
  15. Sivanandy P, Leey TC, Xiang TC, Ling TC, Wey Han SA, Semilan SLA, et al.
    PMID: 35010624 DOI: 10.3390/ijerph19010364
    Parkinson's Disease (PD) is a disease that involves neurodegeneration and is characterised by the motor symptoms which include muscle rigidity, tremor, and bradykinesia. Other non-motor symptoms include pain, depression, anxiety, and psychosis. This disease affects up to ten million people worldwide. The pathophysiology behind PD is due to the neurodegeneration of the nigrostriatal pathway. There are many conventional drugs used in the treatment of PD. However, there are limitations associated with conventional drugs. For instance, levodopa is associated with the on-off phenomenon, and it may induce wearing off as time progresses. Therefore, this review aimed to analyze the newly approved drugs by the United States-Food and Drug Administration (US-FDA) from 2016-2019 as the adjuvant therapy for the treatment of PD symptoms in terms of efficacy and safety. The new drugs include safinamide, istradefylline and pimavanserin. From this review, safinamide is considered to be more efficacious and safer as the adjunct therapy to levodopa as compared to istradefylline in controlling the motor symptoms. In Study 016, both safinamide 50 mg (p = 0.0138) and 100 mg (p = 0.0006) have improved the Unified Parkinson's Disease Rating Scale (UPDRS) part III score as compared to placebo. Improvement in Clinical Global Impression-Change (CGI-C), Clinical Global Impression-Severity of Illness (CGI-S) and off time were also seen in both groups of patients following the morning levodopa dose. Pimavanserin also showed favorable effects in ameliorating the symptoms of Parkinson's Disease Psychosis (PDP). A combination of conventional therapy and non-pharmacological treatment is warranted to enhance the well-being of PD patients.
  16. Ng ZY, Ajeng AA, Cheah WY, Ng EP, Abdullah R, Ling TC
    J Environ Manage, 2024 Jan 01;349:119445.
    PMID: 37890301 DOI: 10.1016/j.jenvman.2023.119445
    Biofertilizers encompass microorganisms that can be applied to plants, subsequently establishing themselves within the plant's rhizosphere or internal structures. This colonization stimulates plant development by enhancing nutrient absorption from the host. While there is growing literature documenting the applications of microalgae-based and bacterial-based biofertilizers, the research focusing on the effectiveness of consortia formed by these microorganisms as short-term plant biofertilizers is notably insufficient. This study seeks to assess the effectiveness of microalgae-bacterial biofertilizers in promoting plant growth and their potential contribution to the circular economy. The review sheds light on the impact of microalgae-bacterial biofertilizers on plant growth parameters, delving into factors influencing their efficiency, microalgae-bacteria interactions, and effects on soil health. The insights from this review are poised to offer valuable guidance to stakeholders in agriculture, including farmers, environmental technologists, and businesses. These insights will aid in the development and investment in more efficient and sustainable methods for enhancing crop yields, aligning with the Sustainable Development Goals and principles of the circular economy.
  17. Cheng SY, Show PL, Lau BF, Chang JS, Ling TC
    Trends Biotechnol, 2019 Nov;37(11):1255-1268.
    PMID: 31174882 DOI: 10.1016/j.tibtech.2019.04.007
    Heavy metal pollution is one of the most pervasive environmental problems globally. Novel finely tuned algae have been proposed as a means to improve the efficacy and selectivity of heavy metal biosorption. This article reviews current research on selective algal heavy metal adsorption and critically discusses the performance of novel biosorbents. We emphasize emerging state-of-the-art techniques that customize algae for enhanced performance and selectivity, particularly molecular and chemical extraction techniques as well as nanoparticle (NP) synthesis approaches. The mechanisms and processes for developing novel algal biosorbents are also presented. Finally, we discuss the applications, challenges, and future prospects for modified algae in heavy metal biosorption.
  18. Chia SR, Show PL, Phang SM, Ling TC, Ong HC
    J Biosci Bioeng, 2018 Aug;126(2):220-225.
    PMID: 29673988 DOI: 10.1016/j.jbiosc.2018.02.015
    In this present study, alcohol/salt liquid biphasic system was used to extract phlorotannin from brown macroalgae. Liquid biphasic system is a new green technology that integrated with various processes into one-step, by concentrating, separating and purifying the bioproduct in a unit operation. The solvent used is non-toxic and there is potential for solvent recovery which is beneficial to the environment. Phlorotannin is a bioactive compound that has gained much attention due to its health beneficial effect. Therefore, the isolation of phlorotannin is lucrative as it contains various biological activities that are capable to be utilised into food and pharmaceutical application. By using 2-propanol/ammonium sulphate system, the highest recovery of phlorotannin was 76.1% and 91.67% with purification factor of 2.49 and 1.59 from Padina australis and Sargassum binderi, respectively. A recycling study was performed and the salt phase of system was recycled where maximum salt recovery of 41.04% and 72.39% could be obtained from systems containing P. australis and S. binderi, respectively. Similar recovery of phlorotannin was observed after performing two cycles of the system, this concludes that the system has good recyclability and eco-friendly.
  19. Phong WN, Le CF, Show PL, Chang JS, Ling TC
    Eng Life Sci, 2017 Apr;17(4):357-369.
    PMID: 32624781 DOI: 10.1002/elsc.201600133
    Microalgae emerge as the most promising protein sources for aquaculture industry. However, the commercial proteins production at low cost remains a challenge. The process of harnessing microalgal proteins involves several steps such as cell disruption, isolation and extraction. The discrete processes are generally complicated, time-consuming and costly. To date, the notion of integrating microalgal cell disruption and proteins recovery process into one step is yet to explore. Hence, this study aimed to investigate the feasibility of applying methanol/potassium ATPS in the integrated process for proteins recovery from Chlorella sorokiniana. Parameters such as salt types, salt concentrations, methanol concentrations, NaCl addition were optimized. The possibility of upscaling and the effectiveness of recycling the phase components were also studied. The results showed that ATPS formed by 30% (w/w) K3PO4 and 20% (w/w) methanol with 3% (w/w) NaCl addition was optimum for proteins recovery. In this system, the partition coefficient and yield were 7.28 and 84.23%, respectively. There were no significant differences in the partition coefficient and yield when the integrated process was upscaled to 100-fold. The recovered phase components can still be recycled effectively at fifth cycle. In conclusions, this method is simple, rapid, environmental friendly and could be implemented at large scale.
  20. Tan YP, Ling TC, Tan WS, Yusoff K, Tey BT
    Protein Expr Purif, 2006 Mar;46(1):114-21.
    PMID: 16139513
    In the present work, a single-step purification of recombinant nucleocapsid protein (NP) of the Newcastle disease virus (NDV) directly from unclarified feedstock using an expanded bed adsorption chromatography (EBAC) was developed. Streamline 25 column (ID = 25 mm) was used as a contactor and Streamline chelating adsorbent immobilized with Ni2+ ion was used as affinity adsorbent. The dynamic binding capacity of Ni2+ -loaded Streamline chelating adsorbent for the NP protein in unclarified feedstock was found to be 2.94 mg ml(-1) adsorbent at a superficial velocity of 200 cm h(-1). The direct purification of NP protein from unclarified feedstock using expanded bed adsorption has resulted in a 31% adsorption and 9.6% recovery of NP protein. The purity of the NP protein recovered was about 70% and the volume of processing fluid was reduced by a factor of 10. The results of the present study show that the IMA-EBAC developed could be used to combine the clarification, concentration and initial purification steps into a single-step operation.
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