Displaying publications 21 - 40 of 61 in total

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  1. Palm-Based Neopentyl Glycol Diester: A Potential Green Insulating Oil
    Raof NA, Yunus R, Rashid U, Azis N, Yaakub Z
    Protein Pept Lett, 2018;25(2):171-179.
    PMID: 29359647 DOI: 10.2174/0929866525666180122095056
    BACKGROUND: The transesterification of high oleic palm oil methyl ester (HOPME) with neopentyl glycol (NPG) has been investigated. The present study revealed the application of low-pressure technology as a new synthesis method to produce NPG diesters. Single variable optimization and response surface methodology (RSM) were implemented to optimize the experimental conditions to achieve the maximum composition (wt%) of NPG diesters.

    OBJECTIVE: The main objective of this study was to optimize the production of NPG diesters and to characterize the optimized esters with typical chemical, physical and electrical properties to study its potential as insulating oil.

    METHODS: The transesterification reaction between HOPME and NPG was conducted in a 1L three-neck flask reactor at specified temperature, pressure, molar ratio and catalyst concentration. For the optimization, four factors have been studied and the diester product was characterized by using gas chromatography (GC) analysis. The synthesized esters were then characterized with typical properties of transformer oil such as flash point, pour point, viscosity and breakdown voltage and were compared with mineral insulating oil and commercial NPG dioleate. For formulation, different samples of NPG diesters with different concentration of pour point depressant were prepared and each sample was tested for its pour point measurement.

    RESULTS: The optimum conditions inferred from the analyses were: molar ratio of HOPME to NPG of 2:1.3, temperature = 182°C, pressure = 0.6 mbar and catalyst concentration of 1.2%. The synthesized NPG diesters showed very important improvement in fire safety compared to mineral oil with flash point of 300°C and 155°C, respectively. NPG diesters also exhibit a relatively good viscosity of 21 cSt. The most striking observation to emerge from the data comparison with NPG diester was the breakdown voltage, which was higher than mineral oil and definitely in conformance to the IEC 61099 limit at 67.5 kV. The formulation of synthesized NPD diesters with VISCOPLEX® pour point depressant has successfully increased the pour point of NPG diester from -14°C to -48°C.

    CONCLUSION: The reaction time for the transesterification of HOPME with NPG to produce NPG diester was successfully reduced to 1 hour from the 14 hours required in the earlier synthesis method. The main highlight of this study was the excess reactant which is no longer methyl ester but the alcohol (NPG). The optimum reaction conditions for the synthesis were molar ratio of 2:1.13 for NPG:HOPME, 182°C, 0.6 mbar and catalyst concentration of 1.2 wt%. The maximum NPG diester yield of 87 wt% was consistent with the predicted yield of 87.7 wt% obtained from RSM. The synthesized diester exhibited better insulating properties than the commercial products especially with regards to the breakdown voltage, flash point and moisture content.

  2. Fulltext Prospects and Challenges of Microwave-Combined Technology for Biodiesel and Biolubricant Production through a Transesterification: A Review
    Mohamad Aziz NA, Yunus R, Kania D, Abd Hamid H
    Molecules, 2021 Feb 03;26(4).
    PMID: 33546303 DOI: 10.3390/molecules26040788
    Biodiesels and biolubricants are synthetic esters produced mainly via a transesterification of other esters from bio-based resources, such as plant-based oils or animal fats. Microwave heating has been used to enhance transesterification reaction by converting an electrical energy into a radiation, becoming part of the internal energy acquired by reactant molecules. This method leads to major energy savings and reduces the reaction time by at least 60% compared to a conventional heating via conduction and convection. However, the application of microwave heating technology alone still suffers from non-homogeneous electromagnetic field distribution, thermally unstable rising temperatures, and insufficient depth of microwave penetration, which reduces the mass transfer efficiency. The strategy of integrating multiple technologies for biodiesel and biolubricant production has gained a great deal of interest in applied chemistry. This review presents an advanced transesterification process that combines microwave heating with other technologies, namely an acoustic cavitation, a vacuum, ionic solvent, and a supercritical/subcritical approach to solve the limitations of the stand-alone microwave-assisted transesterification. The combined technologies allow for the improvement in the overall product yield and energy efficiency. This review provides insights into the broader prospects of microwave heating in the production of bio-based products.
  3. Fulltext Rare Case of Large Catecholamine Secreting Ganglioneuroma in an Asymptomatic Elderly Male
    Soundarajan T, Bidin MBL, Rajoo S, Yunus R
    J ASEAN Fed Endocr Soc, 2022;37(1):87-90.
    PMID: 35800596 DOI: 10.15605/jafes.037.01.10
    Ganglioneuromas (GNs) are benign tumors that originate from neural crest cells, composed mainly of mature ganglion cells. These tumors, which are usually hormonally silent, tend to be discovered incidentally on imaging tests and occur along the paravertebral sympathetic chain, from the neck to the pelvis and occasionally in the adrenal medulla. Rarely, GNs secrete catecholamines.1 Adrenal GNs occur most frequently in the fourth and fifth decades of life, whereas GNs of the retroperitoneum and posterior mediastinum are usually encountered in younger adults.2 Adrenal GNs are commonly hormonally silent and asymptomatic; even when the lesion is of substantial size.3 We report an incidentally detected asymptomatic case of an adrenal ganglioneuroma with mildly elevated urinary catecholamine levels in an elderly male. After preoperative alpha blockade, the patient underwent open right adrenalectomy. Upon microscopic examination, the right adrenal mass proved to be a ganglioneuroma, maturing type and the immunohistochemistry examination showed immunoreactivity to synaptophysin, chromogranin, and CD 56, while S100 was strongly positive at the Schwannian stroma. Following resection, catecholamine levels normalized, confirming the resected right adrenal ganglioneuroma as the source of the catecholamine excess. This case represents a rare presentation of catecholamine-secreting adrenal ganglioneuroma in the elderly.
  4. Fulltext Enhancing construction site performance through technology and management practices as material waste mitigation in the Malaysian construction industry
    Abdullah Abkar MM, Yunus R, Gamil Y, Albaom MA
    Heliyon, 2024 Apr 15;10(7):e28721.
    PMID: 38586423 DOI: 10.1016/j.heliyon.2024.e28721
    The construction industry, increasingly prioritizing sustainability, necessitates an exploration of technology and management's role in mitigating material waste at construction sites. This study examines the impact of 3R, IBS, BIM, and MMA in enhancing Construction Site Performance (CSP) in the Malaysian construction sector. Seven hypotheses were formulated to assess the relationship between technology adoption, material management practices, and the moderating influence of Material Management Adoption (MMA) on CSP. Data were collected through an online survey from 295 valid responses in the Malaysian construction sector, focusing on professionals involved in solid waste management. Utilizing Partial Least Squares - Structural Equation Modeling (PLS-SEM) and Statistical Package for the Social Sciences (SPSS), the findings highlight the importance of technological integration, efficient material management, and competitive strategies in effective material waste mitigation. Furthermore, the qualitative aspect of the study, conducted among 6 solid waste organizations in Malaysia, enriches the findings by providing nuanced insights into local practices and challenges. Emphasizing the importance of contextual insights, the study addresses professionals involved in solid waste management within the Malaysian construction industry. The geographical specificity adds depth to the analysis, offering a comprehensive understanding of regional dynamics. Despite acknowledging limitations in technology and material usage, the study offers recommendations for refining waste mitigation and improving construction site performance. This research model offers actionable insights for construction site stakeholders, emphasizing the criticality of waste mitigation and CSP. The results, both quantitative and qualitative, underscore the potential of these practices within the Malaysian construction industry to foster innovation and drive positive change.
  5. Fulltext Palm oil derived trimethylolpropane triesters synthetic lubricants and usage in industrial metalworking fluid
    Chang TS, Yunus R, Rashid U, Choong TS, Awang Biak DR, Syam AM
    J Oleo Sci, 2015;64(2):143-51.
    PMID: 25748374 DOI: 10.5650/jos.ess14162
    Trimethylolpropane triesters are biodegradable synthetic lubricant base oil alternative to mineral oils, polyalphaolefins and diesters. These oils can be produced from trimethylolpropane (TMP) and fatty acid methyl esters via chemical or enzymatic catalyzed synthesis methods. In the present study, a commercial palm oil derived winter grade biodiesel (ME18) was evaluated as a viable and sustainable methyl ester source for the synthesis of high oleic trimethylolpropane triesters (HO-TMPTE). ME18 has fatty acid profile containing 86.8% oleic acid, 8.7% linoleic acid with the remaining minor concentration of palmitic acid, stearic acid and linolenic acid. It's high oleic property makes it superior to produce synthetic lubricant base oil that fulfills both the good low temperature property as well as good oxidative stability. The synthetic base oil produced had a viscosity of 44.3 mm(2)/s at 40°C meeting the needs for ISO 46 oils. It also exhibited an excellent viscosity index of 219 that is higher than some other commercial brands of trimethylolpropane trioleate. Properties of base oil such as cloud point, density, acid value, demulsibility and soap content were also examined. The oil was then used in the formulation of tapping oil and appraised in term of adaptability, stability and field test performance.
  6. Microwave-assisted biodiesel production by esterification of palm fatty acid distillate
    Lokman IM, Rashid U, Zainal Z, Yunus R, Taufiq-Yap YH
    J Oleo Sci, 2014;63(9):849-55.
    PMID: 25099911
    In the current research work, effect of microwave irradiation energy on the esterification of palm fatty acid distillate (PFAD) to produce PFAD methyl ester / biodiesel was intensively appraised. The PFAD is a by-product from refinery of crude palm oil consisting >85% of free fatty acid (FFA). The esterification reaction process with acid catalyst is needed to convert the FFA into fatty acid methyl ester or known as biodiesel. In this work, fabricated microwave-pulse width modulation (MPWM) reactor with controlled temperature was designed to be capable to increase the PFAD biodiesel production rate. The classical optimization technique was used in order to study the relationship and the optimum condition of variables involved. Consequently, by using MPWM reactor, mixture of methanol-to-PFAD molar ratio of 9:1, 1 wt.% of sulfuric acid catalyst, at 55°C reaction temperature within 15 min reaction time gave 99.5% of FFA conversion. The quality assessment and properties of the product were analyzed according to the American Society for Testing and Materials (ASTM), European (EN) standard methods and all results were in agreement with the standard requirements. It revealed that the use of fabricated MPWM with controlled temperature was significantly affecting the rate of esterification reaction and also increased the production yield of PFAD methyl ester.
  7. Lateral rectus myositis mimicking an abducens nerve palsy in a pregnant woman
    Haslinda AR, Shatriah I, Azhany Y, Nik-Ahmad-Zuky NL, Yunus R
    Ophthalmic Plast Reconstr Surg, 2013 3 28;30(1):e13-5.
    PMID: 23531952 DOI: 10.1097/IOP.0b013e31828957ae
    Myositis is a rare unknown inflammatory disorder of the skeletal muscle tissue. Generalized inflammatory myopathies, polymyositis, and dermatomyositis have been reported during pregnancy. Isolated orbital myositis in pregnancy has not been previously described in the literature. The authors report a case of left isolated orbital myositis in a primigravida at 38 weeks gestation affecting the patient's left lateral rectus muscle. MRI of the orbit was consistent with the diagnosis. She showed remarkable clinical improvement with oral corticosteroids therapy.
  8. Fulltext Rhino-orbito-cerebral mucormycosis in an immunocompetent patient: case report and review of literature
    Shatriah I, Mohd-Amin N, Tuan-Jaafar TN, Khanna RK, Yunus R, Madhavan M
    Middle East Afr J Ophthalmol, 2012 Apr-Jun;19(2):258-61.
    PMID: 22623872 DOI: 10.4103/0974-9233.95269
    Rhino-orbito-cerebral mucormycosis is a fungal infection that can be fatal especially in immunocompromised patients. It is extremely rare in immunocompetent individuals. We describe here an immunocompetent patient who survived rhino-orbito-cerebral mucormycosis due to Saksenaea vasiformis, and provide a literature review of this rare entity.
  9. Extensive facial and orbital infantile hemangiomas associated with high intraocular pressure
    Shatriah I, Norazizah MA, Wan-Hitam WH, Wong AR, Yunus R, Leo SW
    Pediatr Dermatol, 2013 Jan-Feb;30(1):151-4.
    PMID: 22329437 DOI: 10.1111/j.1525-1470.2011.01618.x
    High intraocular pressure is a rare ophthalmic condition associated with infantile hemangiomas that involves the orbit, eyelid, or both. Here, we describe a patient with extensive facial and orbital infantile hemangiomas associated with high intraocular pressure in the affected eye. The prompt management of this challenging condition is essential.
  10. A study of the factors related to intima-media thickness of the common carotid artery amongst rural middle age individuals in Hospital Universiti Sains Malaysia
    Yunus R, Ariff AR, Shuaib IL, Jelani AM, Alias NA, Abdullah J, et al.
    Southeast Asian J. Trop. Med. Public Health, 2006 Jul;37(4):806-11.
    PMID: 17121310
    There is very little data regarding the factors related to intima-media thickness (IMT) of the common carotid artery in normal individuals in those with non-insulin diabetes mellitus and perimenopausal women in Southeast Asian countries. Ultrasound imaging evaluating the carotid artery IMT in those with diabetes and those on hormone replacement therapy (HRT) was performed beginning in August 2000 for a period of nearly two years at the Department of Radiology, Hospital Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. A total of 153 participants were included. Significant differences between the women on HRT and not on HRT were IMT and systolic blood pressure. When comparing those with non-insulin dependent diabetes mellitus (NIDDM) and normal individuals, the significant differences were IMT, total cholesterol level, systolic blood pressure and diastolic blood pressure. IMT was high in those with NIDDM but not in those on HRT. Both those with NIDDM and those on HRT had associated dyslipidemia and systolic hypertension.
  11. Reply to comment to Meta-analysis and systematic review of laparoscopic versus open mesh repair for elective incisional hernia. Jensen K, Jorgensen LN
    Awaiz A, Rahman F, Hossain MB, Yunus RM, Khan S, Memon B, et al.
    Hernia, 2015 Dec;19(6):1027-9.
    PMID: 26496998 DOI: 10.1007/s10029-015-1432-z
  12. Fulltext Study on the spectrophotometric detection of free fatty acids in palm oil utilizing enzymatic reactions
    Azeman NH, Yusof NA, Abdullah J, Yunus R, Hamidon MN, Hajian R
    Molecules, 2015;20(7):12328-40.
    PMID: 26198220 DOI: 10.3390/molecules200712328
    In this paper, a comprehensive study has been made on the detection of free fatty acids (FFAs) in palm oil via an optical technique based on enzymatic aminolysis reactions. FFAs in crude palm oil (CPO) were converted into fatty hydroxamic acids (FHAs) in a biphasic lipid/aqueous medium in the presence of immobilized lipase. The colored compound formed after complexation between FHA and vanadium (V) ion solution was proportional to the FFA content in the CPO samples and was analyzed using a spectrophotometric method. In order to develop a rapid detection system, the parameters involved in the aminolysis process were studied. The utilization of immobilized lipase as catalyst during the aminolysis process offers simplicity in the product isolation and the possibility of conducting the process under extreme reaction conditions. A good agreement was found between the developed method using immobilized Thermomyces lanuginose lipase as catalyst for the aminolysis process and the Malaysian Palm Oil Board (MPOB) standard titration method (R2 = 0.9453).
  13. Fulltext An acceleration of microwave-assisted transesterification of palm oil-based methyl ester into trimethylolpropane ester
    Aziz NAM, Yunus R, Hamid HA, Ghassan AAK, Omar R, Rashid U, et al.
    Sci Rep, 2020 11 12;10(1):19652.
    PMID: 33184363 DOI: 10.1038/s41598-020-76775-y
    Microwave-assisted synthesis is known to accelerate the transesterification process and address the issues associated with the conventional thermal process, such as the processing time and the energy input requirement. Herein, the effect of microwave irradiation on the transesterification of palm oil methyl ester (PME) with trimethylolpropane (TMP) was evaluated. The reaction system was investigated through five process parameters, which were reaction temperature, catalyst, time, molar ratio of TMP to PME and vacuum pressure. The yield of TMP triester at 66.9 wt.% and undesirable fatty soap at 17.4% were obtained at 130 °C, 10 mbar, sodium methoxide solution at 0.6 wt.%, 10 min reaction time and molar ratio of TMP to PME at 1:4. The transesterification of palm oil-based methyl ester to trimethylolpropane ester was 3.1 folds faster in the presence of microwave irradiation. The total energy requirement was markedly reduced as compared to the conventional heating method. The findings indicate that microwave-assisted transesterification could probably be an answer to the quest for a cheaper biodegradable biolubricant.
  14. Fulltext Pertussis clinical case definition: Time for change in developing countries?
    Gopal Krishnan S, Fun WH, Ramadras MD, Yunus R, Lye YF, Sararaks S
    PLoS One, 2019;14(7):e0219534.
    PMID: 31291359 DOI: 10.1371/journal.pone.0219534
    BACKGROUND: Developing countries still struggle with late detection and mortality from pertussis. A review of clinical case definitions is necessary for early disease detection. This paper aimed to study possible clinical characteristics for earlier pertussis detection in a sporadic setting.

    METHODS: We conducted a retrospective review of medical and laboratory records in a general paediatric ward of a district hospital in a developing country. Inclusion criteria were all children hospitalised with nasopharyngeal swab taken for Bordetella pertussis. We compared sensitivity and specificity of World Health Organization diagnostic criteria with other clinical characteristics. Polymerase chain reaction Bordetella pertussis was the gold standard used.

    RESULTS: Out of 207 eligible admissions, the study retrieved 128 complete records. Approximately half of the children were less than 3 months old. The World Health Organization diagnostic criteria had a low sensitivity (15%), but high specificity (92%). In comparison, combinations that included paroxysmal cough, ill contact and facial congestion had higher sensitivity. Increasing cough duration improved specificity while compromising sensitivity.

    CONCLUSION: Several clinical characteristics such as paroxysmal cough, facial congestion and a history of ill contact have potential for early clinical detection. Conventional emphasis on cough duration may hamper early detection.

  15. Fulltext A New Model of Alcoholic Fermentation under a Byproduct Inhibitory Effect
    Zentou H, Zainal Abidin Z, Yunus R, Awang Biak DR, Abdullah Issa M, Yahaya Pudza M
    ACS Omega, 2021 Feb 16;6(6):4137-4146.
    PMID: 33644536 DOI: 10.1021/acsomega.0c04025
    Despite the advantages of continuous fermentation whereby ethanol is selectively removed from the fermenting broth to reduce the end-product inhibition, this process can concentrate minor secondary products to the point where they become toxic to the yeast. This study aims to develop a new mathematical model do describe the inhibitory effect of byproducts on alcoholic fermentation including glycerol, lactic acid, acetic acid, and succinic acid, which were reported as major byproducts during batch alcoholic fermentation. The accumulation of these byproducts during the different stages of batch fermentation has been quantified. The yields of total byproducts, glycerol, acetic acid, and succinic acid per gram of glucose were 0.0442, 0.023, 0.0155, and 0.0054, respectively. It was found that the concentration of these byproducts linearly increases with the increase in glucose concentration in the range of 25-250 g/L. The results have also showed that byproduct concentration has a significant inhibitory effect on specific growth coefficient (μ) whereas no effect was observed on the half-velocity constant (Ks). A new mathematical model of alcoholic fermentation was developed considering the byproduct inhibitory effect, which showed a good performance and more accuracy compared to the classical Monod model.
  16. Fulltext Experimental Study on the Partial Discharge Characteristics of Palm Oil and Coconut Oil Based Al2O3 Nanofluids in the Presence of Sodium Dodecyl Sulfate
    Mohamad NA, Azis N, Jasni J, Kadir MZAA, Yunus R, Yaakub Z
    Nanomaterials (Basel), 2021 Mar 19;11(3).
    PMID: 33808641 DOI: 10.3390/nano11030786
    This experimental study aims to examine the partial discharge (PD) properties of palm oil and coconut oil (CO) based aluminum oxide (Al2O3) nanofluids with and without surfactants. The type of surfactant used in this study was sodium dodecyl sulfate (SDS). The volume concentrations range of Al2O3 dispersed in oil samples was varied from 0.001% to 0.05%. The ratio of surfactants to nanoparticles was set to 1:2. In total, two different types of refined, bleached and deodorized palm oil (RBDPO) and one type of CO were measured for PD. Mineral oil (MO) was also examined for comparison purpose. PDIV measurements for all samples were carried out based on rising voltage method whereby a needle-sphere electrode configuration with a gap distance of 50 mm was chosen in this study. Al2O3 improves the PDIVs of RBDPO, CO and MO whereby the highest improvements of PDIVs are 34%, 39.3% and 27%. The PD amplitude and repetition rate of RBDPO improve by 38% and 81% while for CO, it can increase up to 65% and 80% respectively. The improvement of PD amplitude and repetition rate for MO are 18% and 95%, regardless with and without SDS. Without SDS, the presence of Al2O3 could cause 26%, 75% and 65% reductions of the average emission of light signals for RBDPOA, RBDPOB and CO with the improvement of PD characteristics but both events do not correlate at the same volume concentration of Al2O3. On the other hand, the average emission of light signal levels of the oils increases with the introduction of SDS. The emission of light signal in MO does not correlate with the PD characteristics improvement either with or without SDS.
  17. Fulltext Optic neuritis in a child with biotinidase deficiency: case report and literature review
    Hayati AA, Wan-Hitam WH, Cheong MT, Yunus R, Shatriah I
    Clin Ophthalmol, 2012;6:389-95.
    PMID: 22457589 DOI: 10.2147/OPTH.S29048
    Optic atrophy has often been reported in children with biotinidase deficiency. The visual prognosis is usually poor. This report is of a 6-year-old boy with an early onset of biotinidase deficiency who presented with acute profound visual loss in both eyes. Fundoscopy revealed swollen discs in both eyes, and the imaging was consistent with bilateral optic neuritis. He was treated with systemic corticosteroid, and commenced on oral biotin. The final visual outcome was promising.
  18. Fulltext Ethno-medicine survey of medicinal plants used by villagers in Kudat, Sabah, Malaysia. [Abstract]
    Shimmi SC, Kabir S, Parash MTH, Hossain ABMT, Khaing MS, Muhd Yunus R
    Malaysian Journal of Medicine and Health Sciences, 2019;15(106):65.
    MyJurnal
    ABSTRACTS FOR THE 1ST INTERNATIONAL BORNEO HEALTHCARE AND PUBLIC HEALTH CONFERENCE AND 4TH BORNEO TROPICAL MEDICINE
    AND INFECTIOUS DISEASE CONGRESS. New Frontiers in Health: Expecting the Unexpected; Held at the Faculty of Medicine and Health Sciences, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia; On 3rd-5th September 2019
    Introduction: The use of medicinal plants as a remedy and prevention of diseases based on practical skills, knowledge and therapies was passed down from one generation to the next. It was reported by WHO that, approximately a quarter of the modern drugs were derivatives of plants or herbs, used as traditional medicines. It has contributed greatly in the health care management as the main source of medicine for many of the rural population in Sabah. This preliminary study was carried out to observe the use of medicinal plants in different villages of Kudat and to know about the knowledge of the villagers related to possible side effects of these plants.
    Methods: It was a cross-sectional descriptive study which was carried out in different villages of Kudat, Sabah, Malaysia between August and September 2018. The data were obtained through interviewing the people in different villages by using semi-structured questionnaire. Descriptive statistics were used to present the data.
    Results: Among the 87 participants, 37.9% were male and 62.1% were female. Their mean age was 45.87 (±14.03) and they were mostly from Kadazan-Dusun (50.6%) and Rungus (42.5%). The highest level of education among the participants was SPM (20.7%). Roots, stems, leaves, flowers and fruits of 49 plant species were reported in the treatment of more than 30 types of health conditions. Anaemia, hypertension, diabetes, joint pain, hypercholesterolaemia, fever, asthma, malaria, vomiting and few acute illnesses are mentionable. Majority (71%) of the participants did not have any knowledge about possible side effects of the orally ingested or tropically applied medicinal plants.
    Conclusion: There should be thorough research on dosage, mechanism of action and possible side effects of the medicinal plants and the results of these researches should reach the users of these plants.
  19. Fulltext Removal of Zinc from Aqueous Solution by Optimized Oil Palm Empty Fruit Bunches Biochar as Low Cost Adsorbent
    Zamani SA, Yunus R, Samsuri AW, Salleh MAM, Asady B
    Bioinorg Chem Appl, 2017;2017:7914714.
    PMID: 28420949 DOI: 10.1155/2017/7914714
    This study aims to produce optimized biochar from oil palm empty fruit bunches (OPEFB), as a green, low cost adsorbent for uptake of zinc from aqueous solution. The impact of pyrolysis conditions, namely, highest treatment temperature (HTT), heating rate (HR), and residence time (RT) on biochar yield and adsorption capacity towards zinc, was investigated. Mathematical modeling and optimization of independent variables were performed employing response surface methodology (RSM). HTT was found to be the most influential variable, followed by residence time and heating rate. Based on the central composite design (CCD), two quadratic models were developed to correlate three independent variables to responses. The optimum production condition for OPEFB biochar was found as follows: HTT of 615°C, HR of 8°C/min, and RT of 128 minutes. The optimum biochar showed 15.18 mg/g adsorption capacity for zinc and 25.49% of yield which was in agreement with the predicted values, satisfactory. Results of the characterization of optimum product illustrated well-developed BET surface area and porous structure in optimum product which favored its sorptive ability.
  20. Fulltext Ageing Study of Palm Oil and Coconut Oil in the Presence of Insulation Paper for Transformers Application
    Mohamad NA, Azis N, Jasni J, Ab Kadir MZA, Yunus R, Yaakub Z
    Materials (Basel), 2018 Mar 30;11(4).
    PMID: 29601520 DOI: 10.3390/ma11040532
    This paper presents a sealed ageing study of palm oil (PO) and coconut oil (CO) in the presence of insulation paper. The type of PO under study is refined, bleached, and deodorized palm oil (RBDPO) olein. Three different variations of RBDPO and one sample of CO are aged at temperatures of 90 °C, 110 °C, and 130 °C. The properties of RBDPO and CO as well as paper under ageing are then analysed through dielectric and physicochemical measurements. It is found that the effect of ageing is not significant on the alternating current (AC) breakdown voltages and relative permittivities of RBDPO and CO. There is a slight increment trend of the resistivity for CO, while for all of the RBDPO, the resistivity slightly decreases as the ageing progresses. Only CO shows an apparent reduction of the dielectric dissipation factor. Throughout the ageing time, the acidities of all of the RBDPO and CO remain at low level, while the moisture in oils decreases. The tensile index (TI) of the papers for all of the RBDPO and CO retain more than 50% of the TI. A significant increment of the paper ageing rates of all of the RBDPO and CO is observed at an ageing temperature of 130 °C.
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