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  1. Mechanistic analysis of cavitation assisted transesterification on biodiesel characteristics
    Sajjadi B, Abdul Aziz AR, Ibrahim S
    Ultrason Sonochem, 2015 Jan;22:463-73.
    PMID: 24981808 DOI: 10.1016/j.ultsonch.2014.06.004
    The influence of sonoluminescence transesterification on biodiesel physicochemical properties was investigated and the results were compared to those of traditional mechanical stirring. This study was conducted to identify the mechanistic features of ultrasonication by coupling statistical analysis of the experiments into the simulation of cavitation bubble. Different combinations of operational variables were employed for alkali-catalysis transesterification of palm oil. The experimental results showed that transesterification with ultrasound irradiation could change the biodiesel density by about 0.3kg/m(3); the viscosity by 0.12mm(2)/s; the pour point by about 1-2°C and the flash point by 5°C compared to the traditional method. Furthermore, 93.84% of yield with alcohol to oil molar ratio of 6:1 could be achieved through ultrasound assisted transesterification within only 20min. However, only 89.09% of reaction yield was obtained by traditional macro mixing/heating under the same condition. Based on the simulated oscillation velocity value, the cavitation phenomenon significantly contributed to generation of fine micro emulsion and was able to overcome mass transfer restriction. It was found that the sonoluminescence bubbles reached the temperature of 758-713K, pressure of 235.5-159.55bar, oscillation velocity of 3.5-6.5cm/s, and equilibrium radius of 17.9-13.7 times greater than its initial size under the ambient temperature of 50-64°C at the moment of collapse. This showed that the sonoluminescence bubbles were in the condition in which the decomposition phenomena were activated and the reaction rate was accelerated together with a change in the biodiesel properties.
  2. Fulltext Biodegradation of used motor oil in soil using organic waste amendments
    Abioye OP, Agamuthu P, Abdul Aziz AR
    Biotechnol Res Int, 2012;2012:587041.
    PMID: 22919502 DOI: 10.1155/2012/587041
    Soil and surface water contamination by used lubricating oil is a common occurrence in most developing countries. This has been shown to have harmful effects on the environment and human beings at large. Bioremediation can be an alternative green technology for remediation of such hydrocarbon-contaminated soil. Bioremediation of soil contaminated with 5% and 15% (w/w) used lubricating oil and amended with 10% brewery spent grain (BSG), banana skin (BS), and spent mushroom compost (SMC) was studied for a period of 84 days, under laboratory condition. At the end of 84 days, the highest percentage of oil biodegradation (92%) was recorded in soil contaminated with 5% used lubricating oil and amended with BSG, while only 55% of oil biodegradation was recorded in soil contaminated with 15% used lubricating oil and amended with BSG. Results of first-order kinetic model to determine the rate of biodegradation of used lubricating oil revealed that soil amended with BSG recorded the highest rate of oil biodegradation (0.4361 day(-1)) in 5% oil pollution, while BS amended soil recorded the highest rate of oil biodegradation (0.0556 day(-1)) in 15% oil pollution. The results of this study demonstrated the potential of BSG as a good substrate for enhanced remediation of hydrocarbon contaminated soil at low pollution concentration.
  3. Phytotreatment of soil contaminated with used lubricating oil using Hibiscus cannabinus
    Abioye OP, Agamuthu P, Abdul Aziz AR
    Biodegradation, 2012 Apr;23(2):277-86.
    PMID: 21870160 DOI: 10.1007/s10532-011-9506-9
    Soil contamination by hydrocarbons, especially by used lubricating oil, is a growing problem in developing countries, which poses a serious threat to the environment. Phytoremediation of these contaminated soils offers environmental friendly and a cost effective method for their remediation. Hibiscus cannabinus was studied for the remediation of soil contaminated with 2.5 and 1% used lubricating oil and treated with organic wastes [banana skin (BS), brewery spent grain (BSG) and spent mushroom compost (SMC)] for a period of 90 days under natural conditions. Loss of 86.4 and 91.8% used lubricating oil was recorded in soil contaminated with 2.5 and 1% oil and treated with organic wastes respectively at the end of 90 days. However, 52.5 and 58.9% oil loss was recorded in unamended soil contaminated with 2.5 and 1% oil, respectively. The plant did not accumulate hydrocarbon from the soil but shows appreciable accumulation of Fe and Zn in the root and stem of H. cannabinus at the end of the experiment. The first order kinetic rate of uptake of Fe and Zn in H. cannabinus was higher in organic wastes amendment treatments compared to the unamended treatments, which are extremely low. The results of this study suggest that H. cannabinus has a high potential for remediation of hydrocarbon and heavy metal contaminated soil.
  4. Fulltext Temperature compensation in determining of Remazol black B concentrations using plastic optical fiber based sensor
    Chong SS, Aziz AR, Harun SW, Arof H
    Sensors (Basel), 2014;14(9):15836-48.
    PMID: 25166498 DOI: 10.3390/s140915836
    In this study, the construction and test of tapered plastic optical fiber (POF) sensors, based on an intensity modulation approach are described. Tapered fiber sensors with different diameters of 0.65 mm, 0.45 mm, and 0.35 mm, were used to measure various concentrations of Remazol black B (RBB) dye aqueous solutions at room temperature. The concentrations of the RBB solutions were varied from 0 ppm to 70 ppm. In addition, the effect of varying the temperature of the RBB solution was also investigated. In this case, the output of the sensor was measured at four different temperatures of 27 °C, 30 °C, 35 °C, and 40 °C, while its concentration was fixed at 50 ppm and 100 ppm. The experimental results show that the tapered POF with d = 0.45 mm achieves the best performance with a reasonably good sensitivity of 61 × 10(-4) and a linearity of more than 99%. It also maintains a sufficient and stable signal when heat was applied to the solution with a linearity of more than 97%. Since the transmitted intensity is dependent on both the concentration and temperature of the analyte, multiple linear regression analysis was performed to combine the two independent variables into a single equation. The resulting equation was then validated experimentally and the best agreement between the calculated and experimental results was achieved by the sensor with d = 0.45 mm, where the minimum discrepancy is less than 5%. The authors conclude that POF-based sensors are suitable for RBB dye concentration sensing and, with refinement in fabrication, better results could be achieved. Their low fabrication cost, simple configuration, accuracy, and high sensitivity would attract many potential applications in chemical and biological sensing.
  5. Fulltext Fibre optic sensors for selected wastewater characteristics
    Chong SS, Aziz AR, Harun SW
    Sensors (Basel), 2013 Jul 05;13(7):8640-68.
    PMID: 23881131 DOI: 10.3390/s130708640
    Demand for online and real-time measurements techniques to meet environmental regulation and treatment compliance are increasing. However the conventional techniques, which involve scheduled sampling and chemical analysis can be expensive and time consuming. Therefore cheaper and faster alternatives to monitor wastewater characteristics are required as alternatives to conventional methods. This paper reviews existing conventional techniques and optical and fibre optic sensors to determine selected wastewater characteristics which are colour, Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD). The review confirms that with appropriate configuration, calibration and fibre features the parameters can be determined with accuracy comparable to conventional method. With more research in this area, the potential for using FOS for online and real-time measurement of more wastewater parameters for various types of industrial effluent are promising.
  6. Using D-optimal experimental design to optimise remazol black B mineralisation by Fenton-like peroxidation
    Hasan DB, Abdul Aziz AR, Daud WM
    Environ Technol, 2012 Jun;33(10-12):1111-21.
    PMID: 22856280
    The mineralisation of remazol black B (RBB) was studied at concentrations ranging from 20-1000 mgL(-1). The work was aimed at investigating the Fenton-like peroxidation of RBB at a concentration typically obtained in Batik cottage industries. Other response parameters were degradation and colour removal efficiencies. The parameters that were measured included total organic carbon (TOC), chemical oxygen demand (COD) as well as absorbance for mineralisation, degradation and colour. To optimise the process, the interaction effects of several controlling variables on the treatment process were examined using dispersion matrix-optimal design and response surface analysis. Four specific variables: initial dye concentration (Dye)o; the molar ratio of oxidant to dye organic strength (H2O2):(COD); the mass ratio of the oxidant to the catalyst (H2O2):(Fe3+) and reaction time (t(r)), were observed. Three reduced empirical models, one for each response, were developed for describing the treatment process. For 20, 510 and 1000 mgL(-1), the optimum %TOC reduction and oxidation times were 44% for 95 min, 52% for 52.5 min and 68% for 10 min corresponding to 67, 81 and 75% COD reduction, respectively. The optimum COD reduction and oxidation times were 89% for 95 min, 91% for 10 min and 84% for 95 min for concentrations of 20, 510 and 1000 mg L(-1), respectively. For all concentrations, total colour removal was achieved. A comparison of the results obtained in this study with literature values for traditional Fenton, photo-Fenton and photo-Fenton-like oxidation indicated that the TOC reduction obtained using the Fenton-like process was satisfactory.
  7. Velocity field measurement of a round jet using quantitative schlieren
    Iffa ED, Aziz AR, Malik AS
    Appl Opt, 2011 Feb 10;50(5):618-25.
    PMID: 21343981 DOI: 10.1364/AO.50.000618
    This paper utilizes the background oriented schlieren (BOS) technique to measure the velocity field of a variable density round jet. The density field of the jet is computed based on the light deflection created during the passage of light through the understudy jet. The deflection vector estimation was carried out using phase-based optical flow algorithms. The density field is further exploited to extract the axial and radial velocity vectors with the aid of continuity and energy equations. The experiment is conducted at six different jet-exit temperature values. Additional turbulence parameters, such as velocity variance and power spectral density of the vector field, are also computed. Finally, the measured velocity parameters are compared with the hot wire anemometer measurements and their correlation is displayed.
  8. Recent advances in DNA-based electrochemical biosensors for heavy metal ion detection: A review
    Saidur MR, Aziz AR, Basirun WJ
    Biosens Bioelectron, 2017 Apr 15;90:125-139.
    PMID: 27886599 DOI: 10.1016/j.bios.2016.11.039
    The presence of heavy metal in food chains due to the rapid industrialization poses a serious threat on the environment. Therefore, detection and monitoring of heavy metals contamination are gaining more attention nowadays. However, the current analytical methods (based on spectroscopy) for the detection of heavy metal contamination are often very expensive, tedious and can only be handled by trained personnel. DNA biosensors, which are based on electrochemical transduction, is a sensitive but inexpensive method of detection. The principles, sensitivity, selectivity and challenges of electrochemical biosensors are discussed in this review. This review also highlights the major advances of DNA-based electrochemical biosensors for the detection of heavy metal ions such as Hg(2+), Ag(+), Cu(2+) and Pb(2+).
  9. Fulltext The influence of angiotensin I-converting enzyme (ACE) I/D gene polymorphism on cardiovascular and muscular adaptations following 8 weeks of isometric handgrip training (IHG) in untrained normotensive males
    Yusof HA, Aziz AR, Muhamed AMC
    Biol Sport, 2019 Mar;36(1):81-94.
    PMID: 30899143 DOI: 10.5114/biolsport.2019.79975
    We examined the association between the angiotensin I-converting enzyme (ACE) I/D gene polymorphism and isometric handgrip (IHG) training on cardiovascular and muscular responses among normotensive males. Thirty (II = 10, ID = 10, and DD = 10) normotensive untrained males underwent IHG training at 30% of their maximal voluntary contraction 3 days per week for 8 weeks. Cardiovascular and muscular variables were measured before IHG, after a session of IHG and after 8 weeks of IHG. No significant interaction effect was found between ACE I/D genotype and IHG training session on all dependent variables (all p > 0.05). There was a significant main effect of IHG training session on systolic blood pressure (SBP) (p = 0.002), mean arterial pressure (MAP) (p = 0.015) and handgrip strength (HGS) (p = 0.001) scores, while no difference in diastolic blood pressure (DBP), pulse pressure, or heart rate scores was found. A greater improvement in cardiovascular parameters following 8 weeks of IHG training was observed in participants with the D allele than the I allele (SBP reduction: ID+DD genotype group (-5.53 ± 6.2 mmHg) vs. II genotype group (-1.52 ± 5.3 mmHg)); MAP reduction: ID + DD genotype group (-2.80 ± 4.5 mmHg) vs. II genotype group (-1.45 ± 3.5 mmHg). Eight weeks of IHG training improved cardiovascular and muscular performances of normotensive men. Reduction in SBP and MAP scores in D allele carriers compared to I allele carriers indicates that the ACE I/D polymorphism may have an influence on IHG training adaptation in a normotensive population.
  10. Fulltext Current trends in water-in-diesel emulsion as a fuel
    Yahaya Khan M, Abdul Karim ZA, Hagos FY, Aziz AR, Tan IM
    ScientificWorldJournal, 2014;2014:527472.
    PMID: 24563631 DOI: 10.1155/2014/527472
    Water-in-diesel emulsion (WiDE) is an alternative fuel for CI engines that can be employed with the existing engine setup with no additional engine retrofitting. It has benefits of simultaneous reduction of both NO x and particulate matters in addition to its impact in the combustion efficiency improvement, although this needs further investigation. This review paper addresses the type of emulsion, the microexplosion phenomenon, emulsion stability and physiochemical improvement, and effect of water content on the combustion and emissions of WiDE fuel. The review also covers the recent experimental methodologies used in the investigation of WiDE for both transport and stationary engine applications. In this review, the fuel injection pump and spray nozzle arrangement has been found to be the most critical components as far as the secondary atomization is concerned and further investigation of the effect of these components in the microexplosion of the emulsion is suggested to be center of focus.
  11. Mouth rinsing improves cycling endurance performance during Ramadan fasting in a hot humid environment
    Che Muhamed AM, Mohamed NG, Ismail N, Aziz AR, Singh R
    Appl Physiol Nutr Metab, 2014 Apr;39(4):458-64.
    PMID: 24669987 DOI: 10.1139/apnm-2013-0276
    This study examined the effect of mouth rinsing during endurance cycling in a hot humid environment (32 °C and 75% relative humidity) on athletes in the Ramadan fasted state. Nine trained adolescent male cyclists completed 3 trials that consisted of a carbohydrate mouth-rinse (CMR), a placebo mouth-rinse (PMR), and a no-rinse (NOR) trial during the last 2 weeks of Ramadan. Each trial consisted of a preloading cycle at 65% peak rate of oxygen consumption for 30 min followed by a 10-km time trial (TT10 km) under hot humid condition. During the CMR and PMR trials, each cyclist rinsed his mouth with 25 mL of the solution for 5 s before expectorating the solution pre-exercise, after 5, 15, and 25 min of the preloading cycle, and 15 s prior to the start of TT10 km. Time to complete the TT10 km was significantly faster in the CMR and PMR trials compared with the NOR trial (12.9 ± 1.7 and 12.6 ± 1.7 vs. 16.8 ± 1.6 min, respectively; p < 0.017). Ratings of perceived exertion taken at the end of the TT10 km was lower in both CMR and PMR trials compared with the NOR trial, although the difference was significant only between CMR and NOR (p < 0.05). In conclusion, mouth rinsing with either carbohydrate or placebo solution provided ergogenic benefits compared with a no-rinse condition on TT10 km performance in acute Ramadan fasted subjects during endurance cycling in a heat stress environment.
  12. Self-generated coping strategies among muslim athletes during ramadan fasting
    Roy J, Hwa OC, Singh R, Aziz AR, Jin CW
    J Sports Sci Med, 2011;10(1):137-44.
    PMID: 24149306
    The study explored the self-generated coping strategies employed by Muslim athletes from South East Asian region during the Ramadan fasting month. Sixty-five National elite Muslim athletes responded to an open-ended question on coping strategies employed during Ramadan fasting. Inductive content analysis identified five general dimensions from 54 meaning units which were abstracted into 14 first-order themes and 10 second order themes. The general dimension included four problem-focused coping: training modifications, dietary habits, psychological, rest and recovery, and one emotion-focused coping i.e., self- control. The coping strategies employed were diverse and dynamic in nature and no specific pattern was evident. The most frequently employed strategies were associated with training and dietary habits. Emotion focused coping was the least frequently used by the athletes. Key pointsMuslim athletes employ diverse self -generated coping strategies during Ramadan fasting which can be categorized as anticipatory coping, preventative coping and proactive coping.Frequently employed coping strategies are task focused such as training modifications and adjustments in dietary habits.
  13. The ergogenic potency of carbohydrate mouth rinse on endurance running performance of dehydrated athletes
    Kamaruddin HK, Ooi CH, Mündel T, Aziz AR, Che Muhamed AM
    Eur J Appl Physiol, 2019 Aug;119(8):1711-1723.
    PMID: 31098832 DOI: 10.1007/s00421-019-04161-2
    PURPOSE: To examine the effect of carbohydrate (CHO) mouth rinsing on endurance running responses and performance in dehydrated individuals.

    METHODS: In a double blind, randomised crossover design, 12 well-trained male runners completed 4 running time to exhaustion (TTE) trials at a speed equivalent to 70% of VO2peak in a thermoneutral condition. Throughout each run, participants mouth rinsed and expectorated every 15 min either 25 mL of 6% CHO or a placebo (PLA) solution for 10 s. The four TTEs consisted of two trials in the euhydrated (EU-CHO and EU-PLA) and two trials in the dehydrated (DY-CHO and DY-PLA) state. Prior to each TTE run, participants were dehydrated via exercise and allowed a passive rest period during which they were fed and either rehydrated equivalent to their body mass deficit (i.e., EU trials) or ingested only 50 mL of water (DY trials).

    RESULTS: CHO mouth rinsing significantly improved TTE performance in the DY compared to the EU trials (78.2 ± 4.3 vs. 76.9 ± 3.8 min, P = 0.02). The arousal level of the runners was significantly higher in the DY compared to the EU trials (P = 0.02). There was no significant difference among trials in heart rate, plasma glucose and lactate, and psychological measures.

    CONCLUSIONS: CHO mouth rinsing enhanced running performance significantly more when participants were dehydrated vs. euhydrated due to the greater sensitivity of oral receptors related to thirst and central mediated activation. These results show that level of dehydration alters the effect of brain perception with presence of CHO.

  14. Carbohydrate mouth rinse is no more effective than placebo on running endurance of dehydrated and heat acclimated athletes
    Kamaruddin HK, Farah NMF, Aziz AR, Mündel T, Che Muhamed AM
    Eur J Appl Physiol, 2023 Jul;123(7):1507-1518.
    PMID: 36920510 DOI: 10.1007/s00421-023-05170-y
    PURPOSE: To determine whether carbohydrate mouth rinsing would improve endurance running performance of tropical natives in a warm-humid (30 °C and 70% relative humidity) environment.

    METHOD: Twelve endurance male runners [age 25 ± 3 years; peak aerobic capacity ([Formula: see text]O2peak) 57.6 ± 3.6 mL.kg-1.min-1] completed three time-to-exhaustion (TTE) trials at ~ 70% [Formula: see text]O2peak while swilling 25 ml of a 6% carbohydrate (CHO) or taste-matched placebo (PLA) as well as no mouth rinse performed in the control (CON) trial.

    RESULTS: TTE performance was significantly longer in both CHO and PLA trials when compared with the CON trial (54.7 ± 5.4 and 53.6 ± 5.1 vs. 48.4 ± 3.6 min, respectively; p  0.05). Similarly, plasma lactate and glucose as well as exercise heart rate were not influenced by the trials.

    CONCLUSIONS: The present study demonstrates that mouth rinsing, whether carbohydrate or placebo, provides an ergogenic benefit to running endurance when compared to CON in a heat stress environment. Nevertheless, the results do not support the notion that rinsing a carbohydrate solution provides a greater advantage as previously described among non-heat acclimated individuals within a temperate condition.

  15. Subjective Perception of Sports Performance, Training, Sleep and Dietary Patterns of Malaysian Junior Muslim Athletes during Ramadan Intermittent Fasting
    Singh R, Hwa OC, Roy J, Jin CW, Ismail SM, Lan MF, et al.
    Asian J Sports Med, 2011 Sep;2(3):167-76.
    PMID: 22375236
    To examine the subjective perception of daily acute fasting on sports performance, training, sleep and dietary patterns of Muslim athletes during the Ramadan month.
  16. Ramadan intermittent fasting and its association with health-related indices and exercise test performance in athletes and physically active individuals: an overview of systematic reviews
    Trabelsi K, Ammar A, Boukhris O, Boujelbane MA, Clark C, Romdhani M, et al.
    Br J Sports Med, 2024 Feb 07;58(3):136-143.
    PMID: 37923379 DOI: 10.1136/bjsports-2023-106826
    OBJECTIVE: To systematically review, summarise and appraise findings of published systematic reviews, with/without meta-analyses, examining associations between Ramadan fasting observance (RO), health-related indices and exercise test performances in athletes and physically active individuals.

    DESIGN: Overview of systematic reviews with assessment of reviews' methodological quality.

    DATA SOURCES: PubMed, Web of Science, Scopus, Cochrane Database of Systematic Reviews, SPORTDiscus, ProQuest, PsycINFO and SciELO.

    ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Systematic reviews with/without meta-analyses examining associations of RO with health-related indices and exercise performances in athletes and physically active individuals.

    RESULTS: Fourteen systematic reviews (seven with meta-analyses) of observational studies, with low-to-critically-low methodological quality, were included. Two reviews found associations between RO and decreased sleep duration in athletes and physically active individuals. One review suggested athletes may experience more pronounced reductions in sleep duration than physically active individuals. One review found associations between RO and impaired sleep quality in athletes and physically active individuals. RO was associated with decreased energy, carbohydrate and water intake in adult-aged athletes, but not adolescents. One review suggests RO was associated with athletes' increased feelings of fatigue and decreased vigour. No association was found between RO and athletes' lean mass or haematological indices. RO was unfavourably associated with changes in athletes' performance during high-intensity exercise testing.

    CONCLUSION: Continuance of training during RO could be associated with athletes' mood state disturbances, decreased sleep duration and performance decline during high-intensity exercise testing, while preserving lean mass. However, careful interpretation is necessary due to the low-to-critically-low methodological quality of the included reviews.

  17. Fulltext Training During the COVID-19 Lockdown: Knowledge, Beliefs, and Practices of 12,526 Athletes from 142 Countries and Six Continents
    Washif JA, Farooq A, Krug I, Pyne DB, Verhagen E, Taylor L, et al.
    Sports Med, 2022 04;52(4):933-948.
    PMID: 34687439 DOI: 10.1007/s40279-021-01573-z
    OBJECTIVE: Our objective was to explore the training-related knowledge, beliefs, and practices of athletes and the influence of lockdowns in response to the coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

    METHODS: Athletes (n = 12,526, comprising 13% world class, 21% international, 36% national, 24% state, and 6% recreational) completed an online survey that was available from 17 May to 5 July 2020 and explored their training behaviors (training knowledge, beliefs/attitudes, and practices), including specific questions on their training intensity, frequency, and session duration before and during lockdown (March-June 2020).

    RESULTS: Overall, 85% of athletes wanted to "maintain training," and 79% disagreed with the statement that it is "okay to not train during lockdown," with a greater prevalence for both in higher-level athletes. In total, 60% of athletes considered "coaching by correspondence (remote coaching)" to be sufficient (highest amongst world-class athletes). During lockdown, 

  18. Fulltext Correction to: Training During the COVID-19 Lockdown: Knowledge, Beliefs, and Practices of 12,526 Athletes from 142 Countries and Six Continents
    Washif JA, Farooq A, Krug I, Pyne DB, Verhagen E, Taylor L, et al.
    Sports Med, 2022 Oct 22.
    PMID: 36272061 DOI: 10.1007/s40279-022-01776-y
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