Displaying publications 81 - 100 of 387 in total

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  1. Fixed-bed adsorption performance of oil palm shell-based activated carbon for removal of 2,4,6-trichlorophenol
    Tan IA, Ahmad AL, Hameed BH
    Bioresour Technol, 2009 Feb;100(3):1494-6.
    PMID: 18809316 DOI: 10.1016/j.biortech.2008.08.017
    This study investigated the adsorption potential of oil palm shell-based activated carbon to remove 2,4,6-trichlorophenol from aqueous solution using fixed-bed adsorption column. The effects of 2,4,6-trichlorophenol inlet concentration, feed flow rate and activated carbon bed height on the breakthrough characteristics of the adsorption system were determined. The regeneration efficiency of the oil palm shell-based activated carbon was evaluated using ethanol desorption technique. Through ethanol desorption, 96.25% of the adsorption sites could be recovered from the regenerated activated carbon.
  2. Adsorption of basic dye on high-surface-area activated carbon prepared from coconut husk: equilibrium, kinetic and thermodynamic studies
    Tan IA, Ahmad AL, Hameed BH
    J Hazard Mater, 2008 Jun 15;154(1-3):337-46.
    PMID: 18035483
    Adsorption isotherm and kinetics of methylene blue on activated carbon prepared from coconut husk were determined from batch tests. The effects of contact time (1-30 h), initial dye concentration (50-500 mg/l) and solution temperature (30-50 degrees C) were investigated. Equilibrium data were fitted to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. The equilibrium data were best represented by Langmuir isotherm model, showing maximum monolayer adsorption capacity of 434.78 mg/g. The kinetic data were fitted to pseudo-first-order, pseudo-second-order and intraparticle diffusion models, and was found to follow closely the pseudo-second-order kinetic model. Thermodynamic parameters such as standard enthalpy (DeltaH degrees), standard entropy (DeltaS degrees) and standard free energy (DeltaG degrees) were evaluated. The adsorption interaction was found to be exothermic in nature. Coconut husk-based activated carbon was shown to be a promising adsorbent for removal of methylene blue from aqueous solutions.
  3. Preparation of activated carbon from coconut husk: optimization study on removal of 2,4,6-trichlorophenol using response surface methodology
    Tan IA, Ahmad AL, Hameed BH
    J Hazard Mater, 2008 May 1;153(1-2):709-17.
    PMID: 17935879
    Activated carbon was prepared from coconut husk using physicochemical activation method which consisted of potassium hydroxide (KOH) treatment and carbon dioxide (CO(2)) gasification. The effects of three preparation variables (CO(2) activation temperature, CO(2) activation time and KOH:char impregnation ratio) on the 2,4,6-trichlorophenol (2,4,6-TCP) uptake and activated carbon yield were investigated. Based on the central composite design, two quadratic models were developed to correlate the preparation variables to the two responses. From the analysis of variance (ANOVA), the most influential factor on each experimental design response was identified. The activated carbon preparation conditions were optimized by maximizing both the 2,4,6-TCP uptake and activated carbon yield. The predicted 2,4,6-TCP uptake and carbon yield from the models agreed satisfactorily with the experimental values. The optimum conditions for preparing activated carbon from coconut husk for adsorption of 2,4,6-TCP were found as follow: CO(2) activation temperature of 750 degrees C, CO(2) activation time of 2.29 h and KOH:char impregnation ratio of 2.91, which resulted in 191.73 mg/g of 2,4,6-TCP uptake and 20.16 % of activated carbon yield.
  4. Clinical pathways in primary dental care in Malaysia: clinicians' knowledge, perceptions and barriers faced
    Tay HL, Raja Latifah RJ, Razak IA
    Asia Pac J Public Health, 2006;18(2):33-41.
    PMID: 16883968 DOI: 10.1177/10105395060180020601
    The Oral Health Division, Ministry of Health in Malaysia piloted clinical pathways (cpath) in primary care in early 2003. This study investigated the knowledge, perception of cpaths and barriers faced by the clinicians involved in the pilot project. Self-administered questionnaires were sent to the clinicians (n=191). Dentists (67.9%) and dental nurses (70.6%) had good overall knowledge of cpaths. The majority of the clinicians (67.9% to 95.6%) perceived cpath positively in all areas. Only 9.2% of dentists encountered difficulties in using cpath forms compared to 28.4% of dental nurses. A higher proportion of dental nurses (73.5%) compared to dentists (64.8%) were willing to continue using cpath. The majority of dentists (76.7%) and dental nurses (73.1%) were willing to participate in future development of cpaths. Overall, there was evidence of managerial support for the pilot project. A follow-up of the pilot project was somewhat lacking as less than half (43.3%) of the clinicians reported that the state coordinator obtained feedback from them. The findings auger well for the future implementation of cpath should the Oral Health Division decide to adopt cpath routinely in the public oral health care service.
  5. Enzyme production and profile by Aspergillus niger during solid substrate fermentation using palm kernel cake as substrate
    Ong LG, Abd-Aziz S, Noraini S, Karim MI, Hassan MA
    Appl Biochem Biotechnol, 2004 8 12;118(1-3):73-9.
    PMID: 15304740
    The oil palm sector is one of the major plantation industries in Malaysia. Palm kernel cake is a byproduct of extracted palm kernel oil. Mostly palm kernel cake is wasted or is mixed with other nutrients and used as animal feed, especially for ruminant animals. Recently, palm kernel cake has been identified as an important ingredient for the formulation of animal feed, and it is also exported especially to Europe, South Korea, and Japan. It can barely be consumed by nonruminant (monogastric) animals owing to the high percentages of hemicellulose and cellulose contents. Palm kernel cake must undergo suitable pretreatment in order to decrease the percentage of hemicellulose and cellulose. One of the methods employed in this study is fermentation with microorganisms, particularly fungi, to partially degrade the hemicellulose and cellulose content. This work focused on the production of enzymes by Aspergillus niger and profiling using palm kernel cake as carbon source.
  6. Adsorption characteristics of malachite green on activated carbon derived from rice husks produced by chemical-thermal process
    Rahman IA, Saad B, Shaidan S, Sya Rizal ES
    Bioresour Technol, 2005 Sep;96(14):1578-83.
    PMID: 15978990
    Phosphoric acid (H(3)PO(4)) and sodium hydroxide (NaOH) treated rice husks, followed by carbonization in a flowing nitrogen were used to study the adsorption of malachite green (MG) in aqueous solution. The effect of adsorption on contact time, concentration of MG and adsorbent dosage of the samples treated or carbonized at different temperatures were investigated. The results reveal that the optimum carbonization temperature is 500 degrees C in order to obtain adsorption capacity that is comparable to the commercial activated carbon for the husks treated by H(3)PO(4). It is interesting to note that MG adsorbed preferably on carbon-rich than on silica rich-sites. It is found that the behaviour of H(3)PO(4) treated absorbent followed both the Langmuir and Freundlich models while NaOH treated best fitted to only the Langmuir model.
  7. Fulltext Developing control points for halal slaughtering of poultry
    Shahdan IA, Regenstein JM, Shahabuddin ASM, Rahman MT
    Poult Sci, 2016 Jul 01;95(7):1680-1692.
    PMID: 26994198 DOI: 10.3382/ps/pew092
    Halal (permissible or lawful) poultry meat production must meet industry, economic, and production needs, and government health requirements without compromising the Islamic religious requirements derived from the Qur'an and the Hadiths (the actions and sayings of the Prophet Muhammad, peace and blessings be upon him). Halal certification authorities may vary in their interpretation of these teachings, which leads to differences in halal slaughter requirements. The current study proposes 6 control points (CP) for halal poultry meat production based on the most commonly used halal production systems. CP 1 describes what is allowed and prohibited, such as blood and animal manure, and feed ingredients for halal poultry meat production. CP 2 describes the requirements for humane handling during lairage. CP 3 describes different methods for immobilizing poultry, when immobilization is used, such as water bath stunning. CP 4 describes the importance of intention, details of the halal slaughter, and the equipment permitted. CP 5 and CP 6 describe the requirements after the neck cut has been made such as the time needed before the carcasses can enter the scalding tank, and the potential for meat adulteration with fecal residues and blood. It is important to note that the proposed halal CP program is presented as a starting point for any individual halal certifying body to improve its practices.
  8. Bis(dicyclohexylammonium 3-thienylacetate)
    Ng SW, Chantrapromma S, Razak IA, Fun HK
    Acta Crystallogr C, 2001 Mar;57(Pt 3):291-2.
    PMID: 11250582
    The triclinic cell of the title compound contains 2C(12)H(24)N(+) x 2C(6)H(5)O(2)S(-) ion pairs that are linked by four hydrogen bonds [N...O = 2.728 (3) and 2.758 (3) A] across a centre of inversion.
  9. 1-acetyl-3-[benzoyl(4-methoxyphenyl)methylene]-2,3-dihydro-1H-indol-2-one
    Usman A, Razak IA, Fun HK, Chantrapromma S, Zhang Y, Xu JH
    Acta Crystallogr C, 2001 Dec;57(Pt 12):1438-40.
    PMID: 11740110
    In the title compound, C25H19NO4, the indole moiety is not completely planar, the heterocyclic ring being distorted very slightly towards a half-chair conformation. The benzoyl and 4-methoxyphenyl substituents are individually almost planar and are in a bisecting and nearly perpendicular configuration, respectively, with respect to the plane of the indole moiety. The molecular and packing structures in the crystal are stabilized by intramolecular and intermolecular C-H...O interactions.
  10. Polyvinyl chloride-based membranes for flow injection analysis of quinine in beverages
    Saad B, Bee-Leng Y, Saleh MI, Rahman IA, Mansor SM
    J AOAC Int, 2001 8 15;84(4):1151-7.
    PMID: 11501917
    Potentiometric response characteristics were evaluated for quinine selective sensors based on a lipophilic ion-exchanger potassium tetrakis[3,5-bis(trifluoromethylphenyl)]borate (PTFB) immobilized together with plasticizing solvents in polyvinyl chloride membranes. The use of dioctyl phthalate (DOP), 2-nitrophenyl phenyl ether (NPPE), and bis(2-ethylhexyl)adipate (BEHA) plasticizers produced good quality quinine sensors that were sensitive and fast responding, and exhibited near Nernstian responses when used as batch-sensors. These membranes were further tested in a wall-jet flow-through potentiometric flow injection analysis (FIA) detector. Quinine sensors containing BEHA were the most suitable membrane, with no noticeable differences in sensitivity even after 5 h of continuous exposure to solutions. Interference by foreign species such as alkali, alkaline earth metal ions, sugars, and sodium benzoate was minimal in either the batch-mode (log selectivity coefficients
  11. Utilization, knowledge and attitudes concerning sealants among Malaysian dentists: a national survey
    Abdul Razak IA, Esa R, Jalallundin RL, Jaafar N
    J Pedod, 1990;14(4):242-5.
    PMID: 2098079
    The aim of this postal survey was to assess the utilization, knowledge and attitude concerning sealants among Malaysian dentists. A pretested questionnaire was sent to all dentists (1217) who were on the Dentist Register of Malaysia of 1987. A response rate of 61.1% was obtained. The results indicate that 52.6% of the respondents have used sealants, but of these only 13.6% have used them frequently. The two "knowledge" related questions receiving the most support concerned the suitability of the first permanent molars for sealants and the loss of sealants attributable to problems at the time of application. The two "attitudinal" questions receiving the most support concerned the value of sealants in preventing dental caries and the need for the profession to expand more efforts toward increasing public demand for sealants. Only about 50% of the respondents believed that sealants are cost-effective.
  12. An analysis of sugar content of commonly used pediatric liquid medicines--its relevance to dentistry
    Nik-Hussein NN, Razak IA, Karim MN
    Singapore Dent J, 1988 Dec;13(1):24-6.
    PMID: 3154999
    The sugar content of twenty-four liquid medicines commonly prescribed for infants and young children were measured and the type of sugars present were also identified in four randomly selected samples. All the liquid medicines tested contained sugar, in the range of 29.4% to 61.2%. Sucrose appeared to be the most commonly used sugar. Whilst it is agreed that sucrose makes the medicine more acceptable to children, its continual use by the pharmaceutical industry should be discontinued due to its harmful effect on the dental health of children, particularly those taking these syrup-based medicines on prolonged basis. Sugar-free alternatives such as sorbitol or saccharin should be used instead.
  13. Effects of insulin-like growth factors I and II on oestrone sulphatase activity in human breast cancer cell lines
    Hwa IA, Reimann K, Lim PK, Lai LC
    Int J Mol Med, 1999 Aug;4(2):175-8.
    PMID: 10402485
    Oestrogens play an important role in the development of breast cancer. A very important source of active oestrogens in the breast is oestrone sulphate which is converted to oestrone by oestrone sulphatase. The aim of this study was to assess the effects of IGF-I and IGF-II on oestrone sulphatase activity in, as well as cell growth of, MCF-7 and MDA-MB-231 human breast cancer cell lines. Cells were grown in supplemented DMEM and treated with varying concentrations of IGFs. At the end of the treatment period, intact cell monolayers were washed and assayed for oestrone sulphatase activity and the number of cell nuclei determined on a Coulter Counter. Oestrone sulphatase activity was significantly stimulated by IGF-I and II at concentrations of 100 ng/ml and 200 ng/ml in MCF-7 cells. IGF-I had no effect on oestrone sulphatase activity in MDA-MB-231 cells over the range of concentrations tested. Significant inhibition of oestrone sulphatase was observed in MDA-MB-231 cells at higher concentrations of IGF-II (50 ng/ml, 100 ng/ml and 200 ng/ml). Both IGF-I and IGF-II at higher concentrations (100 ng/ml and 200 ng/ml) significantly inhibited MCF-7 and stimulated MDA-MB-231 cell growth. Since IGF-I and II have effects on cell growth and oestrone sulphatase activity in breast cancer cell lines they may play a role in the development and progression of human breast cancer.
  14. Understanding thermostability factors of Aspergillus niger PhyA phytase: a molecular dynamics study
    Noorbatcha IA, Sultan AM, Salleh HM, Amid A
    Protein J, 2013 Apr;32(4):309-16.
    PMID: 23636517 DOI: 10.1007/s10930-013-9489-y
    Molecular dynamics simulation was used to study the dynamic differences between native Aspergillus niger PhyA phytase and a mutant with 20 % greater thermostability. Atomic root mean square deviation, radius of gyration, and number of hydrogen bonds and salt bridges are examined to determine thermostability factors. The results suggest that, among secondary structure elements, loops have the most impact on the thermal stability of A. niger phytase. In addition, the location rather than the number of hydrogen bonds is found to have an important contribution to thermostability. The results also show that salt bridges may have stabilizing or destabilizing effect on the enzyme and influence its thermostability accordingly.
  15. Adsorption of arsenic using chitosan magnetic graphene oxide nanocomposite
    Sherlala AIA, Raman AAA, Bello MM, Buthiyappan A
    J Environ Manage, 2019 Sep 15;246:547-556.
    PMID: 31202019 DOI: 10.1016/j.jenvman.2019.05.117
    Chitosan-magnetic-graphene oxide (CMGO) nanocomposite was prepared for arsenic adsorption. The nanocomposite was characterized through BET, FTIR, FESEM, EDX, and VSM analyses. These characterizations confirmed the formation of CMGO nanocomposites with high specific surface area (152.38 m2/g) and excellent saturation magnetization (49.30 emu/g). Batch adsorption experiments were conducted to evaluate the performance of the nanocomposite in the adsorption of arsenic from aqueous solution. The effects of operational parameters, adsorption kinetic, equilibrium isotherm and thermodynamics were evaluated. The removal efficiency of arsenic increased with increasing adsorbent dosage and contact time. However, the effect of pH followed a different pattern, with the removal efficiency increasing from acidic to neutral pH, and then decreasing at alkaline conditions. The highest adsorption capacity (45 mg/g) and removal efficiency (61%) were obtained at pH 7.3. The adsorption kinetic followed a pseudo-second-order kinetic model. The analysis of adsorption isotherm shows that the adsorption data fitted well to Langmuir isotherm model, indicating a homogeneous process. Thermodynamic analysis shows that the adsorption of As(III) is exothermic and spontaneous. The superparamagnetic properties of the nanocomposite enabled the separation and recovery of the nanoparticles using an external magnetic field. Thus, the developed nanocomposite has a potential for arsenic remediation.
  16. Carotenoid composition and antioxidant potential of Eucheuma denticulatum, Sargassum polycystum and Caulerpa lentillifera
    Balasubramaniam V, June Chelyn L, Vimala S, Mohd Fairulnizal MN, Brownlee IA, Amin I
    Heliyon, 2020 Aug;6(8):e04654.
    PMID: 32817893 DOI: 10.1016/j.heliyon.2020.e04654
    Three species of Malaysian edible seaweed (Eucheuma denticulatum, Sargassum polycystum and Caulerpa lentillifera) were analyzed for their carotenoid composition using a combination of high-performance thin layer chromatography (HPTLC) and ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS), while the antioxidant capacities were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) assays. The HPTLC analysis exhibited a distinct carotenoid pattern among the three seaweed groups. The UHPLC-ESI-MS/MS analysis showed fucoxanthin as the major carotenoid present in S. polycystum while lutein and zeaxanthin in E. denticulatum. For C. lentillifera, β-carotene and canthaxanthin were the major carotenoids. Some of the carotenoids, such as rubixanthin, dinoxanthin, diatoxanthin and antheraxanthin, were also tentatively detected in E. denticulatum and S. polycystum. For antioxidant activity, S. polycystum (20 %) and E. denticulatum (1128 μmol TE/g) showed the highest activity in the DPPH and ORAC assays, respectively. The findings suggest the three edible varieties of seaweeds may provide a good dietary source with a potential to reduce antioxidative stress.
  17. Fulltext Active infection and morphometric study of Trypanosoma evansi among horses in Peninsula Malaysia
    Elshafie EI, Sani RA, Hassan L, Sharma R, Bashir A, Abubakar IA
    Trop Biomed, 2013 Sep;30(3):444-50.
    PMID: 24189674 MyJurnal
    Apart from occasional reports of clinical disease affecting horses, there is no information about Trypanosoma evansi in horses in Peninsula Malaysia. Thus, a cross-sectional study was conducted in eight states in Peninsula Malaysia to determine the active presence of T. evansi in horses. A total of 527 blood samples were obtained and examined by haematocrit centrifugation technique (HCT), Giemsa-stained thin blood smear (GSS), morphometric measurements, polymerase chain reaction (PCR) and cloning of PCR products. The results showed an overall parasitological prevalence of 0.57% (3/527, CI: 1.6-0.19%) with both HCT and GSS. Morphometric study revealed the mean total length of the trypanosomes including the free flagellum was 27.94 ± 2.63 μm. PCR successfully amplified a trypanosome specific 257 bp in 1.14% of samples (6/527, CI: 2.4-0.52%) and was confirmed by nucleotide sequences. The mean packed cell volume (PCV) for the positive cases detected by HCT was lower (23% ± 7.00) compared to the positive cases detected by PCR alone in the state of Terengganu (35% ± 4.73). In conclusion, this study showed T. evansi infection occurred in low frequency in horses in Peninsula Malaysia, and anaemia coincided with parasitaemic animals. PCR is considered as a sensitive diagnostic tool when parasitaemia is undetectable. The slight lengthier mean of parasite and anaemia may indicate a virulent strain of T. evansi circulating throughout the country. Thus, it's highly recommended to shed light on host-parasite relationship for better epidemiological understanding.
  18. Factors influencing the release of Mitragyna speciosa crude extracts from biodegradable P(3HB-co-4HB)
    Chee JW, Amirul AA, Majid MI, Mansor SM
    Int J Pharm, 2008 Sep 1;361(1-2):1-6.
    PMID: 18584978 DOI: 10.1016/j.ijpharm.2008.05.007
    Copolyesters of 3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB) were produced by Cupriavidus sp. (USMAA2-4) (DSM 19379) from carbon sources of 1,4-butanediol and gamma-butyrolactone. The composition of copolyesters produced varied from 0 to 45 mol% 4HB, depending on the combination of carbon sources supplied. The P(3HB-co-4HB) films containing Mitragyna speciosa crude extract were prepared with the ratio varying from 10 to 40% (w/w). The in vitro crude extract release of the films was studied in 0.1M phosphate buffer (pH 7.4) at 37 degrees C. Although the release rate was slow, it was maintained at a constant rate. This suggests that the crude extract release was due to the polymer degradation because the amount of crude extract released was consistent. The amount of degradation was based on the films' dry weight loss, decrease in molecular weight and surface morphology changes. The degradation rate increased with the 4HB content. This showed that the polymer degradation is dependant on the molecular weight, crystallinity, thermal properties and water permeability. The different drug loading ratio which led to surface morphology changes also gave an effect on polymer degradation.
  19. A review of the applications of organo-functionalized magnetic graphene oxide nanocomposites for heavy metal adsorption
    Sherlala AIA, Raman AAA, Bello MM, Asghar A
    Chemosphere, 2018 Feb;193:1004-1017.
    PMID: 29874727 DOI: 10.1016/j.chemosphere.2017.11.093
    Graphene-based adsorbents have attracted wide interests as effective adsorbents for heavy metals removal from the environment. Due to their excellent electrical, mechanical, optical and transport properties, graphene and its derivatives such as graphene oxide (GO) have found various applications. However, in many applications, surface modification is necessary as pristine graphene/GO may be ineffective in some specific applications such as adsorption of heavy metal ions. Consequently, the modification of graphene/GO using various metals and non-metals is an ongoing research effort in the carbon-material realm. The use of organic materials represents an economical and environmentally friendly approach in modifying GO for environmental applications such as heavy metal adsorption. This review discusses the applications of organo-functionalized GO composites for the adsorption of heavy metals. The aspects reviewed include the commonly used organic materials for modifying GO, the performance of the modified composites in heavy metals adsorption, effects of operational parameters, adsorption mechanisms and kinetic, as well as the stability of the adsorbents. Despite the significant research efforts on GO modification, many aspects such as the interaction between the functional groups and the heavy metal ions, and the quantitative effect of the functional groups are yet to be fully understood. The review, therefore, offers some perspectives on the future research needs.
  20. Measuring initial enamel erosion with quantitative light-induced fluorescence and optical coherence tomography: an in vitro validation study
    Chew HP, Zakian CM, Pretty IA, Ellwood RP
    Caries Res, 2014;48(3):254-62.
    PMID: 24481141 DOI: 10.1159/000354411
    BACKGROUND: Measurement of initial enamel erosion is currently limited to in vitro methods. Optical coherence tomography (OCT) and quantitative light-induced fluorescence (QLF) have been used clinically to study advanced erosion. Little is known about their potential on initial enamel erosion.

    OBJECTIVES: To evaluate the sensitivity of QLF and OCT in detecting initial dental erosion in vitro.

    METHODS: 12 human incisors were embedded in resin except for a window on the buccal surface. Bonding agent was applied to half of the window, creating an exposed and non-exposed area. Baseline measurements were taken with QLF, OCT and surface microhardness. Samples were immersed in orange juice for 60 min and measurements taken stepwise every 10 min. QLF was used to compare the loss of fluorescence between the two areas. The OCT system, OCS1300SS (Thorlabs Ltd.), was used to record the intensity of backscattered light of both areas. Multiple linear regression and paired t test were used to compare the change of the outcome measures.

    RESULTS: All 3 instruments demonstrated significant dose responses with the erosive challenge interval (p < 0.05) and a detection threshold of 10 min from baseline. Thereafter, surface microhardness demonstrated significant changes after every 10 min of erosion, QLF at 4 erosive intervals (20, 40, 50 and 60 min) while OCT at only 2 (50 and 60 min).

    CONCLUSION: It can be concluded that OCT and QLF were able to detect demineralization after 10 min of erosive challenge and could be used to monitor the progression of demineralization of initial enamel erosion in vitro.

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