Displaying publications 41 - 60 of 64 in total

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  1. Lee SP, Ramli A
    Chem Cent J, 2013;7(1):149.
    PMID: 24011181 DOI: 10.1186/1752-153X-7-149
    Catalytic deoxygenation is a prominent process for production of renewable fuels from vegetable oil. In this work, deoxygenation of technical grade methyl oleate to diesel fuel aliphatic hydrocarbons (C15 - C18) is evaluated with several parameters including temperature, hydrogen pressure and reaction time in a stirred batch reactor over Pd/SBA-15 catalysts.
  2. Guangul FM, Sulaiman SA, Ramli A
    Bioresour Technol, 2012 Dec;126:224-32.
    PMID: 23073112 DOI: 10.1016/j.biortech.2012.09.018
    Oil palm frond biomass is abundantly available in Malaysia, but underutilized. In this study, gasifiers were evaluated based on the available literature data and downdraft gasifiers were found to be the best option for the study of oil palm fronds gasification. A downdraft gasifier was constructed with a novel height adjustment mechanism for changing the position of gasifying air and steam inlet. The oil palm fronds gasification results showed that preheating the gasifying air improved the volumetric percentage of H(2) from 8.47% to 10.53%, CO from 22.87% to 24.94%, CH(4) from 2.02% to 2.03%, and higher heating value from 4.66 to 5.31 MJ/Nm(3) of the syngas. In general, the results of the current study demonstrated that oil palm fronds can be used as an alternative energy source in the energy diversification plan of Malaysia through gasification, along with, the resulting syngas quality can be improved by preheating the gasifying air.
  3. Vijayakumar P, Nagarajan M, Ramli A
    J Back Musculoskelet Rehabil, 2012;25(4):225-30.
    PMID: 23220803 DOI: 10.3233/BMR-2012-0337
    Osteitis pubis among soccer athletes is a disabling painful condition and it is difficult to manage without integrating a multimodal treatment approach. There is limited scientific evidence on the effectiveness of exercise in treating Osteitis pubis especially when it progress to a chronic painful condition. The purpose of this case report is to discuss the successful multimodal physiotherapeutic management for a 15-year old soccer athlete diagnosed with stage-IV Osteitis pubis. Land and water based active core muscle strengthening exercises, Proprioceptive neuromuscular facilitation techniques (PNF) and Manual Therapy are some of the essential components incorporated in multimodal intervention approach with emphasis to water based strength and endurance training exercises. The athlete was able to make progress to a successful recovery from his chronic painful condition and accomplished the clearly established clinical outcomes during each phase of rehabilitation.
  4. Lau WC, Rafii MY, Ismail MR, Puteh A, Latif MA, Ramli A
    Front Plant Sci, 2015;6:832.
    PMID: 26528304 DOI: 10.3389/fpls.2015.00832
    After yield, quality is one of the most important aspects of rice breeding. Preference for rice quality varies among cultures and regions; therefore, rice breeders have to tailor the quality according to the preferences of local consumers. Rice quality assessment requires routine chemical analysis procedures. The advancement of molecular marker technology has revolutionized the strategy in breeding programs. The availability of rice genome sequences and the use of forward and reverse genetics approaches facilitate gene discovery and the deciphering of gene functions. A well-characterized gene is the basis for the development of functional markers, which play an important role in plant genotyping and, in particular, marker-assisted breeding. In addition, functional markers offer advantages that counteract the limitations of random DNA markers. Some functional markers have been applied in marker-assisted breeding programs and have successfully improved rice quality to meet local consumers' preferences. Although functional markers offer a plethora of advantages over random genetic markers, the development and application of functional markers should be conducted with care. The decreasing cost of sequencing will enable more functional markers for rice quality improvement to be developed, and application of these markers in rice quality breeding programs is highly anticipated.
  5. Ramli A
    JUMMEC, 2007;10(1):29-33.
    MyJurnal
    Little is known of Malaysian older people’s participation in physical activities, and the purpose of this pilot study is to explore their participation and the barriers. A self-administered questionnaire was given to 80 eligible respondents at the Kuala Lumpur Health Clinic of which 70 responded. Thirty-six (51.4%) were males and 34 (48.6%) were females. There were 26 (37.1%) Malays, 20 (28.6%) Chinese, 18 (25.7%) Indians and 6 (8.6%) of other ethnic groups. Forty (57.1%) took part in some form of physical activities and the remaining 30 (42.9%) reported no participation at all. The Chinese participated actively in physical activities (90%), followed by Indians (66.7%) and Malays (30.8%). The five common activities were walking (60%), tai chi (20%), gardening (12.5%), stretching (2.5%) and cycling (5.0%). Identified barriers to physical activities were lack of time (26.7%), having health problems (26.7%), was already fit (26.7%), no companion to exercise with (13.3%) and no exercise knowledge (6.7%). These findings indicated that emphasis should be given to the females and the Malay ethnic group when planning physical activity education for the older people as they were identified to be the least active groups.
    Study site: Klinik Kesihatan Kuala Lumpur, Wilayah Persekutuan, Malaysia
  6. Cheng SH, Shahar S, Lee FS, Ramli A
    Sains Malaysiana, 2012;41:379-385.
    Rising risk of falls has been associated with injury and dysfunction among the elderly. Therefore, this study was conducted to determine the prevalence of falls and association with nutritional status among 143 elderly patients from medical ward and clinic in Hospital Kuala Lumpur. Anthropometric indicators and bone health status using quantitative ultrasound (QUS) were also assessed. History of falls, functional status and dietary intake based on dietary history was assessed
    through questionnaire which was administered by face-to-face interview with the subjects. Data were analyzed using SPSS software version 16.0 and Foodworks. The past-year prevalence of falls (falls at least once in the previous 12 months) in this study was 32.9%. The past year prevalence of falls in women (40.2%) was higher than in men (17.4%) (p<0.01). Women who had calcium intake less than 300 mg/d (adjusted OR = 3.07, 95% CI = 1.02-9.24) and protein intake < 1 g/kg body weight (adjusted OR = 3.68, 95% CI = 0.98-13.84) were more likely to have a higher risk of falls. In conclusion, one third of the subjects, especially women in this study had a history of falls. Elderly people should be assessed for calcium and protein intake and those with calcium intake less than 300 mg/day and protein intake less than 1 g/kg body weight should be given intervention to reduce falls risk factor and subsequent fall-related co-morbidity.
    Keywords: Elderly patients; falls; nutritional status
  7. Hariraj V, Wo WK, Lee SC, Ramli A
    J Clin Pharmacol, 2023 Oct;63(10):1126-1132.
    PMID: 37291071 DOI: 10.1002/jcph.2289
    Severe cutaneous adverse drug reactions (SCARs) are a life-threatening condition. We aimed to identify all carbamazepine-induced SCARs voluntarily reported to the Malaysian pharmacovigilance database and to compare between children and adults. Adverse drug reaction reports for carbamazepine were extracted from 2000 to 2020, and divided into 2 groups, that is, children (aged 0-17 years) and adults (aged 18 years and above). Age, sex, race, and carbamazepine dose were analyzed using multiple logistic regression. Of 1102 carbamazepine adverse drug reaction reports, 416 reports were SCARs (99 children, 317 adults). Stevens-Johnson syndrome and toxic epidermal necrolysis were the main SCAR types for both age groups. Median time-to-onset for any type of SCAR was 13 days, regardless of age. In children, Malay individuals were 3.6 times more likely to report SCARs (95% confidence interval, 1.356-9.546; P = .010) compared to the Chinese population. In adults, carbamazepine-induced SCARs were reported as 3.6 times higher in those with a daily dose of 200 mg or less as compared to a daily dose of 400 mg or more. (95% confidence interval, 2.257-5.758; P 
  8. Sanusi MSM, Hassan WMSW, Hashim S, Ramli AT
    Appl Radiat Isot, 2021 Aug;174:109791.
    PMID: 34062400 DOI: 10.1016/j.apradiso.2021.109791
    Terrestrial radioactivity monitoring of 238U and 232Th series, and 40K in soil is an essential practice for radioactivity and radiation measurement of a place. In conventional practice, only basic data can be in-situ measured using a survey instrument, for example radioactivity concentration in soil and ambient dose equivalent rate. For other physical quantities, for example organ absorbed dose and organ equivalent dose, the measurement is impossible to be performed and can only be computed using Monte Carlo radiation transport simulations. In the past, most of the works only focused on calculating air-kerma-to-effective dose conversion factors. However, the information on organ dose conversion factors is scarcely documented and reported. This study was conducted to calculate organ absorbed and tissue-weighted equivalent dose conversion factors as a result of exposure from terrestrial gamma radiation. Series of organ dose conversion factors is produced based on computations from Monte Carlo MCNP5 simulations using modelled gamma irradiation geometry and established adult MIRD phantom. The study found out that most of the radiation exposed organs absorb energy at comparable rates, except for dense and superficial tissues i.e., skeleton and skin, which indicated slightly higher values. The good agreement between this work and previous studies demonstrated that our gamma irradiation geometry and modelling of gamma radiation sources are adequate. Therefore, the proposed organ dose conversion factors from this study are reasonably acceptable for dose estimation in environmental radioactivity monitoring practices.
  9. Jamaludin, M.A., Amin, A., Fadzlillah, N. A., Kartika, B., Othman, R., Sani, S., et al.
    MyJurnal
    Vinegar is very popular as traditional ingredient for cooking, pickling, and preservation. It is made from sugar or starch by an alcoholic and acetous fermentation and produces ethanol as a by-product. Alcohol is prohibited to be consumed for Muslim or used as ingredient if it is exceeding the allowable limit as stated by Islamic Council in Malaysia. According to Fatwa Committee National Council of Islamic Religious Affairs Malaysia, natural occurrences of ethanol in food products are acceptable if the ethanol contents are less than 1% in beverages and 0.5% for flavoring or coloring substances for the purpose of stabilization. On the other hand, for specific vinegar product, as stated by Malaysian Food Act and Regulation, acetic acid content must be at least 4%. According to FAO/WHO, a product is to be labelled as vinegar if the acetic acid content is 6% and with a maximum residual alcohol content of 0.5%v/v for wine vinegar and 1%v/v for other vinegars. This study investigated the physiochemical properties of the vinegar from different sources of raw materials. Total solubility (TA) by using Brix method, pH, and alcohol and acetic acid content by GC-TOF/MS of 12 commercial vinegars from Malaysia and abroad were studied. The result shown that for pH value of commercial vinegar are ranged from 2.51-3.14°Brix from 2.10-40.73°Brix, acetic acid is ranged from 0.0253-0.1276% and ethanol content from 0-0.5911%. Thus, this study will come out with the clear observation on ethanol content in fermented product which is vinegar in order to categories the halalness of the product that available in Malaysia market especially the ones that are produced internationally. Lastly, as shown by the profiling study, vinegar that are imported internationally may contain some amount of alcohol in contrast with the one that locally produced in Malaysia and has Halal certification.
  10. Ab Rahman N, Lim MT, Lee FY, Lee SC, Ramli A, Saharudin SN, et al.
    Vaccine, 2022 Jul 30;40(32):4394-4402.
    PMID: 35667917 DOI: 10.1016/j.vaccine.2022.05.075
    BACKGROUND: Rapid deployment of COVID-19 vaccines is challenging for safety surveillance, especially on adverse events of special interest (AESIs) that were not identified during the pre-licensure studies. This study evaluated the risk of hospitalisations for predefined diagnoses among the vaccinated population in Malaysia.

    METHODS: Hospital admissions for selected diagnoses between 1 February 2021 and 30 September 2021 were linked to the national COVID-19 immunisation register. We conducted self-controlled case-series study by identifying individuals who received COVID-19 vaccine and diagnosis of thrombocytopenia, venous thromboembolism, myocardial infarction, myocarditis/pericarditis, arrhythmia, stroke, Bell's Palsy, and convulsion/seizure. The incidence of events was assessed in risk period of 21 days postvaccination relative to the control period. We used conditional Poisson regression to calculate the incidence rate ratio (IRR) and 95% confidence interval (CI) with adjustment for calendar period.

    RESULTS: There was no increase in the risk for myocarditis/pericarditis, Bell's Palsy, stroke, and myocardial infarction in the 21 days following either dose of BNT162b2, CoronaVac, and ChAdOx1 vaccines. A small increased risk of venous thromboembolism (IRR 1.24; 95% CI 1.02, 1.49), arrhythmia (IRR 1.16, 95% CI 1.07, 1.26), and convulsion/seizure (IRR 1.26; 95% CI 1.07, 1.48) was observed among BNT162b2 recipients. No association between CoronaVac vaccine was found with all events except arrhythmia (IRR 1.15; 95% CI 1.01, 1.30). ChAdOx1 vaccine was associated with an increased risk of thrombocytopenia (IRR 2.67; 95% CI 1.21, 5.89) and venous thromboembolism (IRR 2.22; 95% CI 1.17, 4.21).

    CONCLUSION: This study shows acceptable safety profiles of COVID-19 vaccines among recipients of BNT162b2, CoronaVac, and ChAdOx1 vaccines. This information can be used together with effectiveness data for risk-benefit analysis of the vaccination program. Further surveillance with more data is required to assess AESIs following COVID-19 vaccination in short- and long-term.

  11. Aziz Saleh M, Termizi Ramli A, Alajerami Y, Damoom M, Sadiq Aliyu A
    Isotopes Environ Health Stud, 2014;50(1):103-13.
    PMID: 24279290 DOI: 10.1080/10256016.2013.821469
    The radiation survey of the ambient environment was conducted using two gamma detectors, and the measurement results were used in the computation of the mean external radiation dose rate, mean-weighted dose rate and annual effective dose, which are 144 nGy h(-1), 0.891 mSv y(-1) and 178 μSv, respectively. A high-purity germanium detector was used to determine the activity concentrations of (232)Th, (226)Ra and (40)K in soil samples. The results of the gamma spectrometry of the soil samples show radioactivity concentration ranges from 19±1 to 405±13 Bq kg(-1) with a mean value of 137±5 Bq kg(-1) for (232)Th, from 21±2 to 268±9 Bq kg(-1)with a mean value of 78±3 Bq kg(-1) for (226)Ra and from 23±9 to 1268±58 Bq kg(-1) with a mean value of 207±13 Bq kg(-1) for (40)K. Radium equivalent activity (Raeq) and external hazard index (Hex) were 290 Bq kg(-1) and 0.784, respectively, which were safe for the population. The mean lifetime dose and lifetime cancer risk for each person living in the area with average lifetime (70 y) were 12.46 mSv and 7.25×10(-4) Sv year, respectively. The results were compared with values given in United Nations Scientific Committee on the Effects of Atomic Radiation 2000.
  12. Sanusi MS, Ramli AT, Gabdo HT, Garba NN, Heryanshah A, Wagiran H, et al.
    J Environ Radioact, 2014 Sep;135:67-74.
    PMID: 24787672 DOI: 10.1016/j.jenvrad.2014.04.004
    A terrestrial gamma radiation survey for the state of Selangor, Kuala Lumpur and Putrajaya was conducted to obtain baseline data for environmental radiological health practices. Based on soil type, geological background and information from airborne survey maps, 95 survey points statistically representing the study area were determined. The measured doses varied according to geological background and soil types. They ranged from 17 nGy h(-1) to 500 nGy h(-1). The mean terrestrial gamma dose rate in air above the ground was 182 ± 81 nGy h(-1). This is two times higher than the average dose rate of terrestrial gamma radiation in Malaysia which is 92 nGy h(-1) (UNSCEAR 2000). An isodose map was produced to represent exposure rate from natural sources of terrestrial gamma radiation.
  13. Adam D, Ramli A, Shahar S
    Sultan Qaboos Univ Med J, 2016 Feb;16(1):e47-53.
    PMID: 26909213 DOI: 10.18295/squmj.2016.16.01.009
    Cognitive impairment is a common problem among the elderly and is believed to be a precursor to dementia. This study aimed to explore the effectiveness of a combined dance and relaxation intervention as compared to relaxation alone in reducing anxiety and depression levels and improving quality of life (QOL) and cognitive function among the cognitively impaired elderly.
  14. Yusof ZY, Netuveli G, Ramli AS, Sheiham A
    Oral Health Prev Dent, 2006;4(3):165-71.
    PMID: 16961024
    OBJECTIVES: To assess whether or not opportunistic oral cancer screening by dentists to detect pre-malignant or early cancer lesions is feasible. The objective was to analyse the patterns of dental attendance of a national representative sample over a period of 10 years to ascertain whether individuals at high-risk of oral cancer would be accessible for opportunistic oral cancer screening.

    METHODS: Secondary analysis of data extracted from the British Household Panel Survey, a national longitudinal survey (n=5547). Analysis to ascertain whether patterns of attendance for dental check-ups for a period of 10 years (1991-2001) were associated with risk factors for oral cancer such as age, sex, education, social class, smoking status and smoking intensity.

    RESULTS: Males, aged over 40 years, less educated manual workers and smokers were significantly less likely to attend for dental check-ups compared with females and younger, higher educated, higher socio-economic class non-smokers (p < 0.05). Throughout the 10-year period, young people, more than older people, had progressively lower odds ratios of attending. Those with more education used dental services more. Heavy smokers were infrequent attendees.

    CONCLUSIONS: This study suggests that opportunistic oral cancer screening by dentists is not feasible to include high-risk groups as they are not regular attendees over 10 years. Those who would be screened would be the low-risk groups. However, dentists should continue screening all patients as oral precancers are also found in regular attendees. More should be done to encourage the high-risk groups to visit their dentists.

  15. Idris HN, Sanusi MSM, Ramli AT, Solleh MRM, Yahaya F, Ya'cob MZ, et al.
    Appl Radiat Isot, 2024 Apr 16;209:111327.
    PMID: 38642443 DOI: 10.1016/j.apradiso.2024.111327
    Presentation of baseline data on terrestrial gamma radiation (TGR) levels is crucial for assessing the annual effective dose received by the public due to natural radiation exposure. Cumulative doses from various sources can become significant, warranting a spatial understanding of TGR distribution. Few countries have comprehensively mapped TGR on a national scale, often facing challenges due to remote or inaccessible regions. This study investigated the influence of weathered soil groups on TGR dose rates in Sarawak-Borneo, Malaysia, to facilitate insights for TGR projection and isodose mapping. A total of 1044 TGR dose rate measurements were collected using NaI (Tl) scintillation detector survey meters, with a mean of 100 nGy h-1 and a range of 8-375 nGy h-1. Non-parametric statistical analyses of variance using Welch's ANOVA, Brown-Forsythe, and Kruskal-Wallis validated (P-sig.=.000) notable dissimilarities among six categories of superficial-weathered soil. Graphical analysis using Sinclair's cumulative plot revealed deviations at intervals of 50, 80, 100, 120, 175, and 205 nGy h-1. These deviations indicate distinct lithological influences. Skeletal soil (entisols) and podzolic soils had high mean dose rates (148 and 113 nGy h-1, respectively) due to limited development, thus preserving abundant uranium (U) and thorium (Th). Meanwhile, gleysols and thionic soils exhibited compatible means (90 and 82 nGy h-1, respectively), while alluvial (or transported soils) and organic soils displayed lower dose rate ranges (mean of 76 and 47 nGy h-1, respectively), reflecting rapid hydrolysis weathering processes. Simple linear regression analysis revealed a strong relationship between TGR dose rate and mean value of weathered soil groups (y = 0.851x + 0.141 nGy h-1), signifying the significance and magnitude of weathered soil groups' impact on TGR dose rates. The obtained R-value is 0.704, indicating a strong linear correlation among soil group variables, and a Durbin-Watson statistic of 1.41, suggesting positive autocorrelation among residuals, thus positive relationships. An isodose map was successfully developed using the Kriging technique, aligning with lithological features of the study area. Semivariogram analysis reveals spatial dependence within a range of 1.47°, supporting the Kriging technique's suitability for spatial inference. In conclusion, this study has successfully revealed the relationship between TGR dose rates and superficial-weathered soil in Sarawak-Borneo. While the linear relationship is applicable to the Sundaland-Borneo tectonic block, it has potential to be used as a valuable tool for spatial inference of TGR dose rates in isodose development with similar lithologial characteristics, aiding in radiation exposure assessment and environmental monitoring.
  16. Zango ZU, Jumbri K, Sambudi NS, Ramli A, Abu Bakar NHH, Saad B, et al.
    Polymers (Basel), 2020 Nov 10;12(11).
    PMID: 33182825 DOI: 10.3390/polym12112648
    Water-borne emerging pollutants are among the greatest concern of our modern society. Many of these pollutants are categorized as endocrine disruptors due to their environmental toxicities. They are harmful to humans, aquatic animals, and plants, to the larger extent, destroying the ecosystem. Thus, effective environmental remediations of these pollutants became necessary. Among the various remediation techniques, adsorption and photocatalytic degradation have been single out as the most promising. This review is devoted to the compilations and analysis of the role of metal-organic frameworks (MOFs) and their composites as potential materials for such applications. Emerging organic pollutants, like dyes, herbicides, pesticides, pharmaceutical products, phenols, polycyclic aromatic hydrocarbons, and perfluorinated alkyl substances, have been extensively studied. Important parameters that affect these processes, such as surface area, bandgap, percentage removal, equilibrium time, adsorption capacity, and recyclability, are documented. Finally, we paint the current scenario and challenges that need to be addressed for MOFs and their composites to be exploited for commercial applications.
  17. Ariffin F, Ramli AS, Naim N, Selamat MI, Syed-Jamal SJ
    Med J Malaysia, 2014 Oct;69(5):210-5.
    PMID: 25638233
    Dengue is life-threatening and the paediatric population is highly susceptible to complications. Deterioration can occur rapidly and ability to recognise early warning signs is crucial. This study aims to determine the knowledge and awareness of parents and carers and to predict their ability in recognising life-threatening symptoms and signs of dengue in children and to assess their health-seeking behaviour in dengue emergency. Methods This is a crosssectional study involving parents and carers of children ≤ 12 years old in schools and kindergartens in the Gombak district. Demographic details, knowledge on life-threatening symptoms and signs of dengue and health-seeking behaviour were collected using a self-administered questionnaire and knowledge scoring was done. The questionnaire was pilot tested with a Cronbach alpha of 0.82. The results were analysed using SPSS version 20.0. Results Total respondents were 866 with 44.8% men and 55.2% women. The mean age was 40.3 years (SD ± 5.7). Knowledge score of dengue life threatening features among respondents were good (30.0%) to average (56.8%). Respondents were able to recognise fever (98.5%), petechial rash (97.1%) and bleeding (65.2%) but were less able to recognise abdominal pain (22.3%) and passing less urine (28.2%) as life threatening dengue features. However, the ability to recognise fever is a poor predictor in recognising life threatening dengue in children compared to all other symptoms which were good predictors. A respondent that recognise stomach pain or neck stiffness were five times more likely to recognise life-threatening dengue. Respondents preferred to bring their children to the clinic (50.8%) or hospital (37.8%) themselves Instead of calling for ambulance. Worryingly, some would give antipyretics (3.6%) or wait for improvements (7.8%). Conclusion Concerted efforts by the schools, healthcare professionals and health authorities are required to educate parents and carers to identify life-threatening features of dengue and to improve their health seeking-behaviour.
  18. Ramli A, Halmey N, Teng C
    Malays Fam Physician, 2008;3(3):158-61.
    PMID: 25606143
    White coat hypertension (WCHT) and white coat effect (WCE) are often thought to be of the same entity. They are in fact different conditions which carry distinctive definitions and prognostic significance. WCHT is diagnosed when office blood pressure (OBP) is ≥140/90 mmHg on at least 3 occasions, while the average daytime or 24-hour blood pressure is <135/85 mmHg. It is common with 15% prevalence in the general population and may account for over 30% of individuals in whom hypertension is diagnosed. Although individuals with WCHT were reported to have a better cardiovascular (CV) prognosis when compared to those with sustained hypertension and masked hypertension; they were also shown to have a greater prevalence of target organ damage (TOD) and metabolic abnormalities than that of normotensive subjects. In contrast, WCE is defined as the transient elevation of OBP induced by the alerting response to a doctor or a nurse. WCE can occur in both normotensive and hypertensive persons; and is not substantially influenced by reassurance and familiarisation. There is conflicting evidence with regards to prognostic significance of WCE, where most data indicated that it does not predict future TOD, CV morbidity or mortality; with some studies showed otherwise. This case scenario aims to solve the diagnostic perplexity with regards to WCHT and WCE, followed by an evidence-based commentary of how to best manage such conditions.
  19. Rahman NJA, Ramli A, Jumbri K, Uemura Y
    Sci Rep, 2019 11 07;9(1):16223.
    PMID: 31700157 DOI: 10.1038/s41598-019-52771-9
    Bifunctional heterogeneous catalysts have a great potential to overcome the shortcomings of homogeneous and enzymatic catalysts and simplify the biodiesel production processes using low-grade, high-free-fatty-acid feedstock. In this study, we developed ZrO2-based bifunctional heterogeneous catalysts for simultaneous esterification and transesterification of microalgae to biodiesel. To avoid the disadvantage of the low surface area of ZrO2, the catalysts were prepared via a surfactant-assisted sol-gel method, followed by hydrothermal treatments. The response surface methodology central composite design was employed to investigate various factors, like the surfactant/Zr molar ratio, pH, aging time, and temperature on the ZrO2 surface area. The data were statistically analyzed to predict the optimal combination of factors, and further experiments were conducted for verification. Bi2O3 was supported on ZrO2 via the incipient wetness impregnation method. The catalysts were characterized by a variety of techniques, which disclosed that the surfactant-assisted ZrO2 nanoparticles possess higher surface area, better acid-base properties, and well-formed pore structures than bare ZrO2. The highest yield of fatty acid methyl esters (73.21%) was achieved using Bi2O3/ZrO2(CTAB), and the catalytic activity of the developed catalysts was linearly correlated with the total densities of the acidic and basic sites. The mechanism of the simultaneous reactions was also discussed.
  20. Hashim S, Bradley DA, Saripan MI, Ramli AT, Wagiran H
    Appl Radiat Isot, 2010 Apr-May;68(4-5):700-3.
    PMID: 19892557 DOI: 10.1016/j.apradiso.2009.10.027
    This paper describes a preliminary study of the thermoluminescence (TL) response of doped SiO(2) optical fibres subjected to (241)AmBe neutron irradiation. The TL materials, which comprise Al- and Ge-doped silica fibres, were exposed in close contact with the (241)AmBe source to obtain fast neutron interactions through use of measurements obtained with and without a Cd filter (the filter being made to entirely enclose the fibres). The neutron irradiations were performed for exposure times of 1-, 2-, 3-, 5- and 7-days in a neutron tank filled with water. In this study, use was also made of the Monte Carlo N-particle (MCNP) code version 5 (V5) to simulate the neutron irradiations experiment. It was found that the commercially available Ge-doped and Al-doped optical fibres show a linear dose response subjected to fast neutrons from (241)AmBe source up to seven days of irradiations. The simulation performed using MCNP5 also exhibits a similar pattern, albeit differing in sensitivity. The TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre, the total absorption cross section for Ge in both the fast and thermal neutrons region being some ten times greater than that of Al.
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