Displaying publications 1 - 20 of 45 in total

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  1. A hint for abnormal thoracic shadow: look behind the heart
    Siti Kaamilah MZ, Wong YS, Bushra J, Nik Ahmad Fadhil NM, Aisya Natasya M
    Breathe (Sheff), 2023 Sep;19(3):230052.
    PMID: 37719237 DOI: 10.1183/20734735.0052-2023
    Can you diagnose this woman with a history of uterine fibroids in the previous year and a recent finding of intrathoracic mass on chest radiography? https://bit.ly/44mQ9Jj.
  2. Enhancement of energy recovery from caffeine wastewater in constructed wetland-microbial fuel cell through operating conditions
    Teoh TP, Ong SA, Ho LN, Wong YS, Lutpi NA, Tan SM, et al.
    Environ Sci Pollut Res Int, 2023 Jul;30(35):84397-84411.
    PMID: 37358771 DOI: 10.1007/s11356-023-28362-7
    The enhancement of up-flow constructed wetland-microbial fuel cell (UFCW-MFC) performance in energy retrieval from caffeine containing wastewater has been explored via various operating conditions (hydraulic retention time (HRT), multianode (MA), multicathode current collector (MC), external resistance). The anaerobic decaffeination and COD removal improved by 37 and 12% as the HRT extended from 1 to 5 d. The increment in contact time between the microbes and organic substrates promoted the degradation and contributed to higher power output (3.4-fold), CE (eightfold), and NER (14-16-fold). The MA and MC connections facilitated the electron transfer rate and the degradation rate of organic substrates in the multiple anodic zones, which enhanced the removal efficiency in the anaerobic compartment (Caffeine: 4.2%; COD: 7.4%) and led to higher electricity generation (Power: 4.7-fold) and energy recovery (CE: 1.4-fold; NER: 2.3-2.5-fold) compared to SA. The lower external resistance favored the growth of electrogens and induced higher electron flux, where the best treatment performance and electricity production was obtained when the external resistance approached the internal resistance. Overall, it was noteworthy that the optimum operating conditions were achieved with 5 d HRT, MA, and MC connection along with external resistance of 200 Ω, which significantly outperformed the initial conditions (1 d HRT, SA connection, and 1000 Ω) by 43.7 and 29.8% of caffeine and COD removal in the anaerobic compartment, respectively as well as 14-fold of power generation.
  3. Exploring the potential of thermophilic anaerobic co-digestion between agro-industrial waste and water hyacinth: operational performance, kinetic study and degradation pathway
    Chai A, Wong YS, Ong SA, Lutpi NA, Sam ST, Wirach T, et al.
    Bioprocess Biosyst Eng, 2023 Jul;46(7):995-1009.
    PMID: 37160769 DOI: 10.1007/s00449-023-02879-0
    Anaerobic co-digestion (co-AD) of agro-industrial waste, namely, palm oil mill effluent (POME) and sugarcane vinasse (Vn), with water hyacinth (WH) as co-substrate was carried out in two separate Anaerobic Suspended Growth Closed Bioreactors (ASGCBs) under thermophilic (55 °C) conditions. The highest chemical oxygen demand (COD) and soluble COD reduction in co-AD of POME-WH (78.61%, 78.86%) is slightly higher than co-AD of Vn-WH (75.75%, 78.24%). However, VFA reduction in co-AD of POME-WH (96.41%) is higher compared to co-AD of Vn-WH (85.94%). Subsequently, biogas production peaked at 13438 mL/day values and 16122 mL/day for co-AD of POME-WH and Vn-WH, respectively. However, the methane content was higher in the co-AD of POME-WH (72.04%) than in the co-AD of Vn-WH (69.86%). Growth yield (YG), maximum specific substrate utilization rate (rx,max) and maximum specific biomass growth rate (μmax) are higher in co-AD of POME-WH, as supported by the higher mixed liquor volatile suspended solids (MLVSS) and COD reduction efficiency compared to co-AD of Vn-WH. However, methane yield ([Formula: see text]) reported in the co-AD of POME-WH and Vn-WH are 0.2748 and 0.3112 L CH4/g CODreduction, respectively, which suggests that WH is a more suitable co-substrate for Vn compared to POME.
  4. Fulltext Krukenberg tumour as the initial manifestation of lung adenocarcinoma
    Lim GY, Wong YS, Tawil Z, Abdul Kadir RF, Ramanathan A, Natasya Musa A
    Respirol Case Rep, 2023 May;11(5):e01133.
    PMID: 37032709 DOI: 10.1002/rcr2.1133
    Krukenberg tumours are unusual metastatic tumours of the ovary with primary tumours from the stomach, breast and gastrointestinal malignancies. Krukenberg tumour from pulmonary malignancy represents an extremely rare situation. This is an elaboration of a case of young women with Krukenberg tumour rising from lung adenocarcinoma. A 38-year-old woman presented with progressive abdominal distention for the past 2-years. Computed tomography (CT) of thorax, abdomen and pelvis revealed a huge ovarian mass with left lung nodules and left-sided pleural effusion. A detailed immunohistochemical staining on pleural fluid cytology confirmed the diagnosis of metastatic adenocarcinoma of lung origin. She underwent doublet platinum chemotherapy as molecular testing for oncogenic mutation was negative. The patient responded well to chemotherapy with a significant reduction in ovarian tumour size. Early identification of the primary source of Krukenberg tumour is paramount to avoid invasive diagnostic surgical intervention for ovarian metastasis.
  5. Chemical and biological combined treatment for sugarcane vinasse: selection of parameters and performance studies
    Kee WC, Wong YS, Ong SA, Lutpi NA, Sam ST, Dahalan FA, et al.
    Environ Sci Pollut Res Int, 2023 May;30(24):65364-65378.
    PMID: 37081370 DOI: 10.1007/s11356-023-27046-6
    Sugarcane vinasse has been reported as a high strength industrial wastewater that could cause severe environmental pollution due to its complex and bio-refractory compounds. Thus, the combined coagulation and sequencing batch biofilm reactor (SBBR) system was employed for the sugarcane vinasse treatment. This study aims to determine the recommended conditions of various parameters under coagulation and SBBR and investigate the effectiveness of combined processes. First, the approach of the coagulation process could achieve the maximum COD reduction and decolorization efficiencies of 79.0 ± 3.4% and 94.1 ± 1.9%, respectively, under the recommended conditions. Next, SBBR as an integrated biofilm reactor showed excellent synergistic biodegradability, removing 86.6 ± 4.3% COD concentration and 94.6 ± 3.8% color concentration at 3.0 g·COD/L of substrate loading concentration. The kinetic studies of SBBR revealed that the first-order kinetic model was the best fit for COD reduction efficiency. In contrast, the second-order kinetic model was the best fit for decolorization efficiency. The SBBR reaction was further investigated by ultraviolet-visible spectrophotometry (UV-Vis). In the combined processes, SBBR followed by the coagulation process (SBBR-CP) showed greater COD reduction and decolorization efficiencies (97.5 ± 0.3 and 99.4 ± 0.1%) when compared to the coagulation process followed by SBBR (CP-SBBR). This study demonstrated the removal performance and potential application of the combined sequential process to produce effluent that can be reused for bioethanol production and fertigation. This finding provides additional insight for developing effective vinasse treatment using combined chemical and biological processes.
  6. Transformation from biofiltration unit to hybrid constructed wetland-microbial fuel cell: Improvement of wastewater treatment performance and energy recovery
    Teoh TP, Koo CJ, Ho LN, Wong YS, Lutpi NA, Tan SM, et al.
    Environ Sci Pollut Res Int, 2023 Apr 04.
    PMID: 37016256 DOI: 10.1007/s11356-023-26789-6
    This study aimed to compare the performance of biofiltration, constructed wetland, and constructed wetland microbial fuel cell (CW-MFC). The transformation from a biofiltration unit to a hybrid CW-MFC was demonstrated with the advantages of improvement of wastewater treatment while generating electricity simultaneously. The introduction of plants to the upper region of the bioreactor enhanced the DO level by 0.8 mg/L, ammonium removal by 5 %, and COD removal by 1 %. The integration of electrodes and external circuits stimulated the degradation rate of organic matter in the anodic region (1 % without aeration and 3 % with aeration) and produced 5.13 mW/m3 of maximum power density. Artificial aeration improved the nitrification efficiency by 38 % and further removed the residual COD to an efficiency of 99 %. The maximum power density was also increased by 3.2 times (16.71 mW/m3) with the aid of aeration. In treating higher organic loading wastewater (3M), the maximum power density showed a significant increment to 78.01 mW/m3 (4.6-fold) and the COD removal efficiency was 98 %. The ohmic overpotential dominated the proportion of total loss (67-91 %), which could be ascribed to the low ionic conductivity. The reduction in activation and concentration loss contributed to the lower internal resistance with the additional aeration and higher organic loading. Overall, the transformation from biofiltration to a hybrid CW-MFC system is worthwhile since the systems quite resemble while CW-MFC could improve the wastewater treatment as well as recover energy from the treated wastewater.
  7. Fulltext Reconceptualizing mind wandering from a switching perspective
    Wong YS, Willoughby AR, Machado L
    Psychol Res, 2023 Mar;87(2):357-372.
    PMID: 35348846 DOI: 10.1007/s00426-022-01676-w
    Mind wandering is a universal phenomenon in which our attention shifts away from the task at hand toward task-unrelated thoughts. Despite it inherently involving a shift in mental set, little is known about the role of cognitive flexibility in mind wandering. In this article we consider the potential of cognitive flexibility as a mechanism for mediating and/or regulating the occurrence of mind wandering. Our review begins with a brief introduction to the prominent theories of mind wandering-the executive failure hypothesis, the decoupling hypothesis, the process-occurrence framework, and the resource-control account of sustained attention. Then, after discussing their respective merits and weaknesses, we put forward a new perspective of mind wandering focused on cognitive flexibility, which provides an account more in line with the data to date, including why older populations experience a reduction in mind wandering. After summarizing initial evidence prompting this new perspective, drawn from several mind-wandering and task-switching studies, we recommend avenues for future research aimed at further understanding the importance of cognitive flexibility in mind wandering.
  8. Intermolecular degradation of aromatic compound and its derivatives via combined sequential and hybridized process
    Lau YY, Wong YS, Ong SA, Lutpi NA, Sam ST, Teng TT, et al.
    Bioprocess Biosyst Eng, 2023 Mar;46(3):359-371.
    PMID: 35796867 DOI: 10.1007/s00449-022-02743-7
    The under-treated wastewater, especially remaining carcinogenic aromatic compounds in wastewater discharge has been expansively reported, wherein the efficiency of conventional wastewater treatment is identified as the primary contributor source. Herein, the advancement of wastewater treatments has drawn much attention in recent years. In the current study, combined sequential and hybridized treatment of thermolysis and coagulation-flocculation provides a novel advancement for environmental emerging pollutant (EP) prescription. This research is mainly demonstrating the mitigation efficiency and degradation pathway of pararosaniline (PRA) hybridized and combined sequential wastewater treatment. Notably, PRA degradation dominantly via a linkage of reaction: thermal cleavage, deamination, silication and diazene reduction. Thermolysis acts as an initiator for the PRA decomposition through thermally induced bond dissociation energy (BDE) for molecular fragmentation whilst coagulation-flocculation facilitates the formation of organo-bridged silsesquioxane as the final degradation product. Different from conventional treatment, the hybridized treatment showed excellent synergistic degradability by removing 99% PRA and its EPs, followed by combined sequential treatment method with 86% reduction. Comprehensive degradation pathway breakdown of carcinogenic and hardly degradable aromatic compounds provides a new insight for wastewater treatment whereby aniline and benzene are entirely undetectable in effluent. The degradation intermediates, reaction derivatives and end products were affirmed by gas chromatography-mass spectrometry, Fourier transform infrared spectroscopy and ultraviolet-visible spectrophotometry (GC-MS, FTIR and UV-Vis). This finding provides valuable guidance in establishing efficient integrated multiple-step wastewater treatments.
  9. Insights into the decolorization of mono and diazo dyes in single and binary dyes containing wastewater and electricity generation in up-flow constructed wetland coupled microbial fuel cell
    Teoh TP, Ong SA, Ho LN, Wong YS, Lutpi NA, Oon YL, et al.
    Environ Sci Pollut Res Int, 2023 Feb;30(7):17546-17563.
    PMID: 36197611 DOI: 10.1007/s11356-022-23101-w
    The treatment of single and binary azo dyes, as well as the effect of the circuit connection, aeration, and plant on the performance of UFCW-MFC, were explored in this study. The decolorization efficiency of Remazol Yellow FG (RY) (single dye: 98.2 %; binary dye: 92.3 %) was higher than Reactive Black 5 (RB5) (single: 92.3 %; binary: 86.7 %), which could be due to monoazo dye (RY) requiring fewer electrons to break the azo bond compared to the diazo dye (RB5). In contrast, the higher decolorization rate of RB5 in binary dye indicated the removal rate was affected by the electron-withdrawing groups in the dye structure. The closed circuit enhanced about 2% of color and 4% of COD removal. Aeration improved the COD removal by 6%, which could be contributed by the mineralization of intermediates. The toxicity of azo dyes was reduced by 11-26% and the degradation pathways were proposed. The dye removal by the plants was increased with a higher contact time. RB5 was more favorable to be uptook by the plant as RB5 holds a higher partial positive charge. 127.39 (RY), 125.82 (RB5), and 58.66 mW/m3 (binary) of maximum power density were generated. The lower power production in treating the binary dye could be due to more electrons being utilized for the degradation of higher dye concentration. Overall, the UFCW-MFC operated in a closed circuit, aerated, and planted conditions achieved the optimum performance in treating binary azo dyes containing wastewater (dye: 87-92%; COD: 91%) compared to the other conditions (dye: 83-92%; COD: 78-87%).
  10. Fulltext Degradation of Diazo Congo Red Dye by Using Synthesized Poly-Ferric-Silicate-Sulphate through Co-Polymerization Process
    Zainudin NF, Sam ST, Wong YS, Ismail H, Walli S, Inoue K, et al.
    Polymers (Basel), 2023 Jan 03;15(1).
    PMID: 36616587 DOI: 10.3390/polym15010237
    The ability of poly-ferric-silicate-sulphate (PFSS) synthesized via a co-polymerization process has been applied for the removal of diazo Congo red dye. A novel degradation pathway of diazo Congo red dye by using PFSS is proposed based on LC-MS analysis. Diazo Congo red dye was successfully removed using synthesized PFSS at lower coagulant dosages and a wider pH range, i.e., 9 mg/L from pH 5 to 7, 11 mg/L at pH 9, and 50 mg/L at pH 11. The azo bond cleavage was verified by the UV-Vis spectra of diazo Congo red-loaded PFSS and FTIR spectra which showed disappearance of the peak at 1584 cm-1 for -N=N- stretching vibrations. The synchronized results of UV-Vis spectra, FTIR, and the LC-MS analysis in this study confirmed the significance of the Si and Fe bond in PFSS towards the degradation of diazo Congo red dye. The successfully synthesized PFSS coagulant was characterized by FTIR, SEM, TEM, and HRTEM analysis. From this analysis, it was proven that PFSS is a polycrystalline material which is favorable for the coagulation-flocculation process. Based on all these findings, it was established that synthesized PFSS can be employed as a highly efficient polymeric coagulant for the removal of dye from wastewater.
  11. Fulltext Unilateral pulmonary artery agenesis: An unusual cause of hemoptysis
    Wong YS, Abidin ZZ, Musa AN, Kadir RFA, Johari B
    Respir Med Case Rep, 2023;43:101834.
    PMID: 36950023 DOI: 10.1016/j.rmcr.2023.101834
    INTRODUCTION: Unilateral pulmonary artery agenesis (UPAA) is a rare congenital malformation of the pulmonary artery due to agenesis of the sixth aortic arch during embryogenesis. Diagnosis can be challenging due to variable clinical presentations.

    CASE: A 29-year-old female at third trimester of twin pregnancy presented with massive hemoptysis. Computed tomography angiogram (CTA) showed unilateral absence of the right pulmonary artery with multiple dilated tortuous bronchial arteries supplying the right lung. Selective embolization of the bronchial artery was performed post-partum.

    CONCLUSION: Clinicians should have a high clinical suspicion of collateral artery bleeding in patients who present with unexplained hemoptysis and typical UPAA radiographic findings.

  12. Fulltext Photocatalytic Degradation of Sugarcane Vinasse Using ZnO Photocatalyst: Operating Parameters, Kinetic Studies, Phytotoxicity Assessments, and Reusability
    Kee WC, Wong YS, Ong SA, Lutpi NA, Sam ST, Chai A, et al.
    Int J Environ Res, 2022;16(1):3.
    PMID: 34899925 DOI: 10.1007/s41742-021-00382-6
    Abstract: Photocatalytic degradation performance is highly related to optimized operating parameters such as initial concentration, pH value, and catalyst dosage. In this study, the impact of various parameters on the photocatalytic degradation of anaerobically digested vinasse (AnVE) has been determined through decolourization and chemical oxygen demand (COD) reduction efficiency using zinc oxide (ZnO) photocatalyst. In this context, the application of photocatalytic degradation in treating sugarcane vinasse using ZnO is yet to be explored. The COD reduction efficiency and decolourization achieved 83.40% and 99.29%, respectively, under the conditions of 250 mg/L initial COD concentration, pH 10, and 2.0 g/L catalyst dosage. The phytotoxicity assessment was also conducted to determine the toxicity of AnVE before and after treatment using mung bean (Vigna radiata). The reduction of root length and the weight of mung bean indicated that the sugarcane vinasse contains enormous amounts of organic substances that affect the plant's growth. The toxicity reduction in the AnVE solution can be proved by UV-Vis absorption spectra. Furthermore, the catalyst recovery achieved 93% in the reusability test. However, the COD reduction efficiency and decolourization were reduced every cycle. It was due to the depletion of the active sites in the catalyst with the adsorption of organic molecules. Thus, it can be concluded that the photocatalytic degradation in the treatment of AnVE was effective in organic degradation, decolorization, toxicity reduction and can be reused after the recovery process.

    Graphical abstract:

  13. Haldane-Andrews substrate inhibition kinetics for pilot scale thermophilic anaerobic degradation of sugarcane vinasse
    Chai A, Wong YS, Ong SA, Aminah Lutpi N, Sam ST, Kee WC, et al.
    Bioresour Technol, 2021 Sep;336:125319.
    PMID: 34049168 DOI: 10.1016/j.biortech.2021.125319
    A pilot scale anaerobic degradation of sugarcane vinasse was carried out at various hydraulic retention time (HRT) in the Anaerobic Suspended Growth Closed Bioreactor (ASGCB) under thermophilic temperature. The performance and kinetics were evaluated through the Haldane-Andrews model to investigate the substrate inhibition potential of sugarcane vinasse. All parameters show great performance between HRT 35 and 25 days: chemical oxygen demand (COD) reduction efficiency (81.6 to 86.8%), volatile fatty acids (VFA) reduction efficiency (92.4 to 98.5%), maximum methane yield (70%) and maximum biogas production (19.35 L/day). Furthermore, steady state values from various HRT were obtained in the kinetic evaluation for: rXmax (1.20 /day), Ks (19.95 gCOD/L), Ki (7.00 gCOD/L) and [Formula: see text] (0.33 LCH4/gCOD reduction). This study shows that anaerobic degradation of sugarcane vinasse through ASGCB could perform well at high HRT and provides a low degree of substrate inhibition as compared to existing studies from literature.
  14. Fulltext Factors Associated with Intention to Donate Hematopoietic Stem Cells among Blood Donors
    Ting CY, Lee YF, Lim CJ, Ting RSK, Md Zahrin MM, Ahmad AS, et al.
    Transfus Med Hemother, 2021 May;48(3):188-195.
    PMID: 34177425 DOI: 10.1159/000512197
    Introduction: Past studies pay little attention to the intention to donate hematopoietic stem cells (HSC) among blood donors. This study investigated the level of and the influence of socio-demographic characteristics, knowledge, attitude, subjective norm and self-efficacy on the intention to donate HSC among blood donors.

    Methods: This cross-sectional study recruited blood donors at selected public hospitals in the Malaysian State of Sarawak in 2019. A structured questionnaire was developed based on the review of relevant literature. It gathered information on socio-demographic characteristics, knowledge, attitude, subjective norm and self-efficacy on the intention to donate HSC. Variables with a p value <0.200 in bivariate analysis were included in the variable selection for regression modeling to examine their associations with the intention to donate HSC.

    Results: A total of 569 blood donors participated (94.5% response rate). Overall, 87.1% reported a positive intention to donate HSC. In the regression model, the factor with the greatest association with intention to donate HSC was subjective norms about HSC donation (β = 0.35, 95% CI 0.27-0.42), followed by attitude about regulations of HSC donation (β= 0.21, 95% CI 0.13-0.35), self-efficacy on HSC donation (β = 0.15, 95% CI 0.09-0.32), attitude about the potential side effects of HSC donation (β = 0.14, 95% CI 0.02-0.10) and highest education level (β = 0.10, 95% CI 0.03-0.44).

    Conclusions: The findings can be used to formulate a better strategy in promoting HSC donation among blood donors in the region.

  15. Fulltext Revealing the influences of functional groups in azo dyes on the degradation efficiency and power output in solar photocatalytic fuel cell
    Khalik WF, Ho LN, Ong SA, Wong YS, Yusoff NA, Lee SL
    J Environ Health Sci Eng, 2020 Dec;18(2):769-777.
    PMID: 33312601 DOI: 10.1007/s40201-020-00502-y
    In this study, the degradation efficiency and electricity generation of the azo dyes affected by the functional groups and molecular structure in a solar photocatalytic fuel cell (PFC) system were investigated and discussed in detail. Four different azo dyes such as, Acid Orange 7 (AO7), Acid Red 18 (AR18), Reactive Black 5 (RB5), Reactive Red 120 (RR120) with different molecular structure were evaluated. The degradation efficiency of AO7, AR18, RB5 and RR120 achieved 5.6 ± 0.3%, 11.1 ± 0.6%, 41.9 ± 0.9% and 52.1 ± 1.3%, respectively, after 6 h irradiated under solar light. In addition, the maximum power density, Pmax for AO7, AR18, RB5 and RR120 was 0.0269 ± 0.01, 0.111 ± 0.03, 1.665 ± 0.67 and 4.806 ± 1.79 mW cm-2, respectively. Meanwhile, the concentration of COD for AO7, AR18, RB5 and RR120 reduced to 16 ± 0.1, 10 ± 0.3, 7 ± 0.6 and 3 ± 0.9 mg L-1, respectively. The concentration ratio of benzene / naphthalene, benzene / azo bond and naphthalene / azo bond, respectively, was analyzed to investigate the impact of the functional groups over photodegradation of the azo dyes in PFC. Electron releasing groups (-OH and -NH2) and electron withdrawing groups (-SO3Na) which attached to the naphthalene or benzene ring also played a pivotal role in the degradation mechanism.
  16. Fulltext The reaction of wastewater treatment and power generation of single chamber microbial fuel cell against substrate concentration and anode distributions
    Tan SM, Ong SA, Ho LN, Wong YS, Thung WE, Teoh TP
    J Environ Health Sci Eng, 2020 Dec;18(2):793-807.
    PMID: 33312603 DOI: 10.1007/s40201-020-00504-w
    This study demonstrated the effectiveness of single chamber up-flow membrane-less microbial fuel cell (UFML-MFC) in wastewater treatment concurrently with bioelectricity generation. The objectives of this study were to examine the effect of influent substrate concentration (0.405 g/L, 0.810 g/L, 1.215 g/L, 1.620 g/L), anode distributions (11 cm, 17 cm, 23 cm ) and surface morphologies for biofilm formation on the performance of wastewater treatment and power generation. The optimum performance was obtained with substrate concentration of 0.810 g/L. The COD removal efficiency, output voltage, internal resistance, power density and current density obtained were 84.64%, 610 mV, 200 Ω, 162.59 mW/m2 and 468.74 mA/m2, respectively. The Coulombic Efficiency (CE), Normalized Energy Recovery (NERS and NERv) were 1.03%, 789.38 kWh/kg COD and 22.56 kWh/m3, respectively. The results also indicate that the output voltage and power generation obtained in a continuous up-flow MFC were higher with A3 (23 cm), which is of larger electrodes spacing followed by A2 (17 cm) and A1 (11 cm) caused by the enrichment of anaerobic microbial population at A1.
  17. Constructed wetland-microbial fuel cell for azo dyes degradation and energy recovery: Influence of molecular structure, kinetics, mechanisms and degradation pathways
    Oon YL, Ong SA, Ho LN, Wong YS, Dahalan FA, Oon YS, et al.
    Sci Total Environ, 2020 Jun 10;720:137370.
    PMID: 32325554 DOI: 10.1016/j.scitotenv.2020.137370
    Complete degradation of azo dye has always been a challenge due to the refractory nature of azo dye. An innovative hybrid system, constructed wetland-microbial fuel cell (CW-MFC) was developed for simultaneous azo dye remediation and energy recovery. This study investigated the effect of circuit connection and the influence of azo dye molecular structures on the degradation rate of azo dye and bioelectricity generation. The closed circuit system exhibited higher chemical oxygen demand (COD) removal and decolourisation efficiencies compared to the open circuit system. The wastewater treatment performances of different operating systems were ranked in the decreasing order of CW-MFC (R1 planted-closed circuit) > MFC (R2 plant-free-closed circuit) > CW (R1 planted-open circuit) > bioreactor (R2 plant-free-open circuit). The highest decolourisation rate was achieved by Acid Red 18 (AR18), 96%, followed by Acid Orange 7 (AO7), 67% and Congo Red (CR), 60%. The voltage outputs of the three azo dyes were ranked in the decreasing order of AR18 > AO7 > CR. The results disclosed that the decolourisation performance was significantly influenced by the azo dye structure and the moieties at the proximity of azo bond; the naphthol type azo dye with a lower number of azo bond and more electron-withdrawing groups could cause azo bond to be more electrophilic and more reductive for decolourisation. Moreover, the degradation pathway of AR18, AO7 and CR were elucidated based on the respective dye intermediate products identified through UV-Vis spectrophotometry, high-performance liquid chromatography (HPLC), and gas chromatograph-mass spectrometer (GC-MS) analyses. The CW-MFC system demonstrated high capability of decolouring azo dyes at the anaerobic anodic region and further mineralising dye intermediates at the aerobic cathodic region to less harmful or non-toxic products.
  18. Stressful life events and depressive symptoms among adolescents in Malaysia: the mediating role of maladaptive cognitive schema
    Wong YS, Zulkefly NS, Tan KA
    Int J Adolesc Med Health, 2020 Jun 08;33(6):493-500.
    PMID: 32549164 DOI: 10.1515/ijamh-2019-0228
    OBJECTIVES: The present study aimed to examine the mediational role of maladaptive cognitive schema in the association between stressful life events, which are operationalised as major (i. e. negative life events) and minor (i. e. daily hassles) life stressors, and depressive symptoms among adolescents.

    METHODS: A cross-sectional correlational study was conducted to recruit participants across four selected states of Kedah, Kelantan, Melaka and Selangor in Peninsular Malaysia. This study involved a total of 1,032 adolescents from 25 government secondary schools, identified using probability proportional to size cluster sampling technique. Data were collected through a self-report questionnaire.

    RESULTS: Using structural equation modelling analyses, findings revealed a full mediation effect of maladaptive cognitive schema between negative life events and depressive symptoms, and a partial mediation effect between daily hassles and depressive symptoms.

    CONCLUSIONS: This study provided valuable insights about the significance of maladaptive cognitive schema as a mediator in the stress-depression association and advanced the understanding of mechanism underlying development of depressive symptoms among adolescents in Malaysia. Findings also benefit the clinical practice in the development of targeted depression prevention and intervention programs.

  19. Performance of the hybrid growth sequencing batch reactor (HG-SBR) for biodegradation of phenol under various toxicity conditions
    Yusoff N, Ong SA, Ho LN, Wong YS, Saad FNM, Khalik W, et al.
    J Environ Sci (China), 2019 Jan;75:64-72.
    PMID: 30473308 DOI: 10.1016/j.jes.2018.03.001
    Hybrid growth microorganisms in sequencing batch reactors have proven effective for treating the toxic compound phenol, but the toxicity effect under different toxicity conditions has rarely been discussed. Therefore, the performance of the HG-SBR under toxic, acute and chronic organic loading can provide the overall operating conditions of the system. Toxic organic loading (TOL) was monitored during the first 7hr while introducing 50mg/L phenol to the system. The system was adversely affected with the sudden introduction of phenol to the virgin activated sludge, which caused a low degradation rate and high dissolved oxygen consumption during TOL. Acute organic loading (AOL) had significant effects at high phenol concentrations (600, 800 1000mg/L). The specific oxygen uptake rate (SOUR) gradually decreased to 4.9mg O2/(g MLVSS·hr) at 1000mg/L of phenol compared to 12.74mg O2/(g MLVSS·hr) for 200mg/L of phenol. The HG-SBR was further monitored during chronic organic loading (COL) over 67days. The effects of organic loading were more apparent at 800mg/L and 1000mg/L phenol concentrations, as the removal range was between 22%-30% and 18%-46% respectively, which indicated the severe effects of COL.
  20. Enhancement of simultaneous batik wastewater treatment and electricity generation in photocatalytic fuel cell
    Khalik WF, Ho LN, Ong SA, Voon CH, Wong YS, Yusuf SY, et al.
    Environ Sci Pollut Res Int, 2018 Dec;25(35):35164-35175.
    PMID: 30328543 DOI: 10.1007/s11356-018-3414-z
    The objective of this study was to investigate several operating parameters, such as open circuit, different external resistance, pH, supporting electrolyte, and presence of aeration that might enhance the degradation rate as well as electricity generation of batik wastewater in solar photocatalytic fuel cell (PFC). The optimum degradation of batik wastewater was at pH 9 with external resistor 250 Ω. It was observed that open circuit of PFC showed only 17.2 ± 7.5% of removal efficiency, meanwhile the degradation rate of batik wastewater was enhanced to 31.9 ± 15.0% for closed circuit with external resistor 250 Ω. The decolorization of batik wastewater in the absence of photocatalyst due to the absorption of light irradiation by dye molecules and this process was known as photolysis. The degradation of batik wastewater increased as the external resistor value decreased. In addition, the degradation rate of batik wastewater also increased at pH 9 which was 74.4 ± 34.9% and at pH 3, its degradation rate was reduced to 19.4 ± 8.7%. The presence of aeration and sodium chloride as supporting electrolyte in batik wastewater also affected its degradation and electricity generation. The maximum absorbance of wavelength (λmax) of batik wastewater at 535 nm and chemical oxygen demand gradually decreased as increased in irradiation time; however, batik wastewater required prolonged irradiation time to fully degrade and mineralize in PFC system.
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