Displaying publications 1 - 20 of 705 in total

  1. Normala, H., Suhaimi, M.I.
    One of the compounds present in Pluchea indica extracts is antioxidant which plays an important role in inhibiting free radicals and thus protects humans against infections and degenerative diseases, such as cancer, arthritis, and ageing process. The main objective of this study was to investigate and determine the total phenolic compounds of Pluchea indica in different concentrations of ethanolic extracts. This species was chosen because of its high phytonutrient compounds with potential medicinal properties. There was a significant difference (P ≤ 0.05) in the total phenolic among the different parts of the tested plant. 50% of the ethanolic extract produced the highest total phenolic compounds (1775.00±86.00 to 658.95±5.00 µmol/g), followed by water extract (759.79±1.53 µmol/g) and 100% ethanol extract (352.72±22.30 to 249.29±5.37 µmol/g), respectively. In terms of the plant parts, the leaves contained the highest phenolic compounds (1775.00±86.00 µmol/g in 50% ethanol extract, 759.79±1.53 µmol/g in 100% aqueous extract and 352.72±22.30 µmol/g in 100% ethanol extract), followed by the stems (990.22±24.00 µmol/g in 50% ethanol extract, 990.22±24.59 µmol/g in 100% aqueous extract and 293.48±0.00 µmol/g in 100% ethanol extract). Meanwhile, lower total phenolic compounds were detected in the flowers (727.71±11.00 µmol/g in 50% ethanol extract, 603.81±8.46 µmol/g in 100% aqueous extract and 249.29±5.37 µmol/g in 100% ethanol extract) and roots (658.95±5.00 µmol/g in 50% ethanol extract, 450.00±10.76 µmol/g in 100% aqueous extract and 272.28±0.53 µmol/g in 100% ethanol extract). Based on these findings, Pluchea indica has potential medicinal properties that can be further developed to produce neutraceutical products, diet supplements or cosmetic products. However, further research should first be conducted on the effects of these compounds on laboratory animals.
  2. Khozirah, S., Rain, A. Noor, Siti Najila, M.J., Rohaya, C., Rosilawati, M., Nuziah, H., et al.
    The antiplasmodial activity of the crude extracts of thirty plant species collected from Sabah was evaluated using chloroquine-sensitive strain (D10) and chloroquine-resistant strain (Gombak A) of Plasmodium falciparum. Significant activities were observed for the bark extract of Polyalthia insignis (IC50 3.89 and 11.89 mg/ml against Gombak A and D10, respectively), the leaf extracts of Kopsia dasyrachis (4.62 mg/ml against Gombak A) and Litsea elliptibacea (IC50 8.88 mg/ml against Gombak A), as well as the leaf and bark extracts of Neouvaria acuminatissima (IC50 6.90-10.08 and 0.69 mg/ml against Gombak A and D10, respectively), and the bark extract of Polyalthia microtus(IC50 9.0 and 12.12 mg/ml against Gombak A and D10, respectively).
  3. Shitan, Mahendran, Kok, Wei Ling
    Modelling observed meteorological elements can be useful. For instance, modelling rainfall has
    been an interest for many researchers. In a previous research, trend surface analysis was used and
    it was indicated that the residuals might spatially be correlated. When dealing with spatial data, any
    modelling technique should take spatial correlation into consideration. Hence, in this project, fitting
    of spatial regression models, with spatially correlated errors to the annual mean relative humidity
    observed in Peninsular Malaysia, is illustrated. The data used in this study comprised of the annual
    mean relative humidity for the year 2000-2004, observed at twenty principal meteorological stations
    distributed throughout Peninsular Malaysia. The modelling process was done using the S-plus
    Spatial Statistics Module. A total of twelve models were considered in this study and the selection
    of the model was based on the p-value. It was found that a possible appropriate model for the
    annual mean relative humidity should include an intercept and a term of the longitude as covariate,
    together with a conditional autoregressive error structure. The significance of the coefficient of the
    covariate and spatial parameter was established using the Likelihood Ratio Test. The usefulness
    of the proposed model is that it could be used to estimate the annual mean relative humidity at
    places where observations were not recorded and also for prediction. Some other potential models
    incorporating the latitude covariate have also been proposed as viable alternatives.
  4. Suniza, A.M.S., Zaleha Kassim, Chatterji, Anil
    Respiratory metabolism of the larvae of Malaysian horseshoe crab Tachypleus gigas (Müller) was studied under different salinities, pH, and temperature. The trend in oxygen consumption was uniform at all salinities, ranging from 10-40 ppt, indicating insignificant influence on the oxygen consumption by the larvae. Similarly, the correlation coefficient values showed that the relationship between oxygen consumption and salinity was not significant (P > 0.05; r = 0.245). During the first three hours, the oxygen consumption was 8.89, 10.72, 17.4, and 12.06% at 10, 20, 30, and 40 ppt salinities, respectively. Meanwhile, the maximum oxygen consumption was recorded after 12 hrs, i.e. at salinity 20 ppt. A sudden drop in oxygen consumption was recorded during 3-6 hours of the experiment. This was followed by a gradual increase in the consumption of oxygen up to 12 hours of experiment. A similar trend in the oxygen consumption was observed in different pH levels, ranging from 5 to 9. At pH 6 and 9, during the first six hour, a moderate consumption of oxygen was observed. However, at pH 6, 7 and 8, the rates of oxygen consumption were found to be relatively greater after six hours, indicating unfavourable conditions. The data were statistically tested and it was found that a high degree of correlations existed between pH and oxygen consumption (r = 0.97). The analysis of covariance showed a significant relationship between oxygen consumption and pH (P < 0.05). Meanwhile, minimal variation in oxygen consumption was recorded between 30 and 40oC, with a
    gradual decrease in dissolved oxygen concentration up to 12 hours of experimental time. At 50oC,
    almost all dissolved oxygen was consumed by the larvae. The rate of oxygen consumption between
    30 and 40oC was low during the first 9 hours of the experiment but it was significantly increased at later hours. A sudden increase in the oxygen consumption was recorded at 50oC, suggesting that it
    might be the most unfavourable temperature condition. Meanwhile, a significant relationship was
    observed between temperature and oxygen consumption (P < 0.05; r = 0.98).
  5. Saidatulnisa Abdullah, Shitan, Mahendran
    The analysis of the spatial data has been carried out in many disciplines such as demography, meteorology, geology and remote sensing. The spatial data modelling is important because it recognizes the phenomenon of spatial correlation in field experiments. Three main categories of the spatial models, namely, the simultaneous autoregressive (SAR) models (Whittle, 1954), the conditional autoregressive (CAR) models (Bartlett, 1971), and the moving average (MA) models (Haining, 1978) have been studied. Whittle (1954) presented a form of bilateral autoregressive (AR) models, whereas Basu and Reinsel (1993) considered the first-order autoregressive moving average (ARMA) model of the quadrant type. Awang, N. and Mahendran Shitan (2003) presented the second-order ARMA model, and established some explicit stationary conditions for the model. When fitting the spatial models and making prediction, it is assumed that, the properties of the process would not change with sites. Properties like stationarities have to be assumed, and for this reason, it was therefore imperative that the researchers had made certain that the process was stationary. This could be achieved by providing the explicit stationarity conditions for the model. The explicit conditions, for a stationary representation of the second-order spatial unilateral ARMA model denoted as ARMA(2,1;2,1), have been established (Awang, N. and Mahendran Shitan, 2003) and in this paper, some explicit conditions are established for a stationary representation of the second-order spatial unilateral ARMA model, denoted as ARMA(2,2;2,2).
  6. Mashitah Mat Don, Yus Azila Yahaya, Bhatia, Subhash
    The removal of heavy metals like lead, copper and cadmium from wastewater streams is an important environmental issue. The capability of immobilized Pycnoporus sanguineus (P. sanguineus), a white-rot macrofungi to remove heavy metals from aqueous solution in a packed bed column was investigated. Lead (Pb (II)) biosorption by immobilized cells of P. sanguineus was investigated in a packed bed column. The experiments were carried out by considering the effect of bed height (5-13 cm), flow rate (4-12 ml min-1) and initial lead (II) concentration (50-300 mg L-1). The breakthrough profiles showed that the saturation of metal ions was achieved faster for 5 cm bed height and 12 ml min-1 influent flow rate. However, the breakthrough time decreased as the initial metal concentration increased from 50 to 300 mg L-1. The column was regenerated using 0.1M HCl solution and biosorptiondesorption studies were carried out for 2 cycles. The results showed that the breakthrough time decreased as the number of cycle was proceeded.
  7. Lim, C.M., Ee, G.C.L., Rahmani, M., Bong, C.F.J.
    An investigation, on the roots of Piper nigrum and the aerial parts of Piper betle, has yielded several alkaloids. The dried root sample of Piper nigrum was extracted using various solvents in increasing polarity. The dried aerial part of Piper betle was extracted using the Soxhlet extraction method. The alkaloids isolated were pellitorine(1), (E)-1-[3’,4’- (Methylenedioxy)cinnamoyl]piperidine(2), piperine(3), piperolactam D(4), cepharadione A(5), and 2,4-tetradecadienoic acid isobutyl amide(6). These compounds were isolated using chromatographic methods, while the elucidation of the structures was carried out using MS, IR and NMR techniques. The xtracts of Piper nigrum and Piper betle were also tested for cytotoxicity activities. This is the first report on E)-1-[3’,4’-(Methylenedioxy)cinnamoyl] piperidine(2) from Piper nigrum as a natural product.
  8. Ahmad Zakuan Ahmad Azmi, Mohd. Saaid, Irawan, Sonny
    The present project investigated the potential of utilizing corncobs and sugar cane waste as viscosivier in drilling fluid. For this purpose, the synthetic-based drilling fluid, Sarapar 147, was used as the base fluid. Both the materials were subjected to pre-treatment of drying, dehumidifying, grinding and sieving process prior to rheological tests. The rheological tests were conducted in accordance with the API 13B specifications to measure mud density, plastic viscosity, yield point, 10-second and 10-minute gel strength. The study found that plastic viscosity and yield point had a direct relationship with the amount of materials added. To drill fluid additive with corn cobs, the density, plastic viscosity and yield point were increased when the amount of additives were increased. Based on these experiments, both additives were found to have the potential to be used as additive in drilling fluid. In particular, they were able to improve its rheological properties by increasing the density, plastic viscosity and yield point. The suitable concentration for the corn cobs and sugar cane is 6.45 lb/bbl and 9.43 lb/bbl, respectively.
  9. Nor Azah Yusof, Beyan, Appri, Md. Haron Jelas, Nor Azowa Ibrahim
    A molecularly imprinted polymer (MIP), with the ability to bind Pb(II) ion, was prepared using the non-covalent molecular imprinting methods and evaluated as a sorbent for the Pb(II) ion uptake. 4-vinylbenzoic acid was chosen as the complexing monomer. The imprinted polymer was synthesized by radical polymerization. The template (Pb(II) ions) was removed using 0.1 M HCl. As a result, the efficient adsorption was found to occur at pH 7. The result also showed the applicability of the Langmuir model for the sorption, with the maximum sorption capacity of 204.08 μg/mg.
  10. Md Rowshon Kamal, Mohd Amin Mohd Soom, Abdul Rashid Mohamed Shariff
    A GIS-based user-interface programme was developed to compute the geospatial Water ProductivityIndex (WPI) of a river-fed rice irrigation scheme in Northwest Selangor, Malaysia. The spatial analysisincludes irrigation blocks with sizes ranging from 20 to 300 ha. The amount of daily water use for eachirrigation block was determined using irrigation delivery model and stored in the database for both mainseason (August to December) and off season (February to May). After cut-off of the irrigation supply,a sub-module was used to compute the total water use including rainfall for each irrigation block. Therice yield data for both seasons were obtained from DOA (Department of Agriculture, Malaysia) of thescheme. Then, the Water Productivity Index (WPI) was computed for each irrigation block and spatialthematic map was also generated. ArcObjects and Visual Basic Application (VBA) programminglanguages were used to structure user-interface in the ArcGIS software. The WPI, expressed in termsof crop yield per unit amount of water used (irrigation and effective rainfall), ranged from 0.02 to 0.57kg/m3 in the main season and 0.02 to 0.40 in off season among irrigation blocks, respectively. Thedevelopment of the overall system and the procedure are illustrated using the data obtained from thestudy area. The approach could be used to depict the gaps between the existing and appropriate watermanagement practices. Suitable interventions could be made to fill the gaps and enhance water useefficiency at the field level and also help in saving irrigation water through remedial measures in theseason. The approach could be useful for irrigation managers to rectify and enhance decision-makingin both the management and operation of the next irrigation season.
  11. Yusof Hamzah, Naurah Mat Isa, Wan Md Zin Wan Yunus
    Covalently cross-linked nanogels were prepared via irradiation of inverse micelles that had been preparedfrom radiation crosslinkable polymer, water, oil and surfactant. A mixture of polymer, water, heptane andsodium dioctyl sulfosuccinate (AOT) at certain compositions forms inverse micelles with the size rangingfrom 2 to 8 nm. The hydrophilic head of the surfactant facilitates encapsulation of water soluble polymer.If the entrapped polymer is radiation crosslinkable, it is expected that upon irradiation, polymerizationshall take place in such small and confined space, leading to formation of nano-sized polymeric gel.Meanwhile, emulsion at 2 nm size was chosen for gamma irradiation process. The formation of thenano-sized discreet gel using irradiation of inverse micelles technique was proven at a dose as low as 5kGy to obtain nanogel sized ~ 95 nm.
  12. Agung, E.H., Sapuan, S.M., Hamdan, M.M., Zaman, H.M.D.K., Mustofa, U.
    The properties of fibre-reinforced composites are dependent not only on the strength of the reinforcementfibre but also on the distribution of fibre strength and the composition of the chemicals or additivesaddition within the composites. In this study, the tensile properties of abaca fibre reinforced high impactpolystyrene (HIPS) composites, which had been produced with the parameters of fibre loading (30,40,50wt.%), coupling agent maleic anhydride (MAH) (1,2,3 wt%) and impact modifier (4,5,6 wt.%) weremeasured. The optimum amount of MAH is 3% and the impact modifier is 6% and these give the besttensile properties. Meanwhile, Differential Scanning Calorimetry (DSC) was used to study the thermalbehaviour within the optimum conditions of the composites. In this research, glass transitions temperature(Tg) of neat HIPS occurred below the Tg of the optimum condition of composites as the temperature ofan amorphous state. The endothermic peak of the composites was in the range of 430-4350C, includingneat HIPS. It was observed that enthalpy of the abaca fibre reinforced HIPS composites yielded belowthe neat HIPS of 748.79 J/g.
  13. Ahmad, M.B., Hashim, K.B., Mohd Yazid, N., Zainuddin, N.
    In this work, hydrogels were prepared from carboxymethyl cellulose (CMC) and 1-vinyl-2-pyrrolidone(VP) by Electron Beam irradiation in the presence of N,N'-methylenebisacrylamide (BIS) as a crosslinkingagent. The parameters studied include stirring time and percentage of crosslinking agent. Hydrogels werecharacterized using Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy(SEM). VP and BIS were found be effective as reinforcement materials to improve the properties ofCMC. Meanwhile, the optimum conditions were 5% BIS and 3 hours of stirring time. The gel fractionincreased when irradiation dose was increased. FTIR confirmed the crosslinking reaction between CMCand VP after the irradiation process by using BIS as the crosslinking agent. TGA thermograms showedchanges in the thermal properties of CMC-VP hydrogels in the presence of different amounts of BIS.
  14. Fathinul Fikri, A.S., Abdul Jalil Nordin
    The incidence of ureteric calculus as a cause for severe abdominal pain in children is mounting, especiallyin the tropical country. The course of illness may be non-specific but a swift detection via non-invasiveimaging modalities singly or in combination may avert unnecessary radiation hazard and futile surgery ina young child. In this paper, we discussed a case of an 11 year-old boy who was presented with a suddenonset of the right side severe abdominal colic whose a bedside ultrasound was positive for hydronephrosisfor which localisation of stone was further confirmed via a low dose limited intravenous urography (IVU).It is important to note that data available on the value of a combined ultrasound and the limited IVU inan emergency setting when urolithiais is being suspected in children with abdominal pain are particularlyscarce. Hence, this case documented the potential value of a combined ultrasound and a limited IVUstudy as a unique combined armamentarium used in a suspected childhood urolithiasis in the tropics.
  15. Mohamed Hasnain Isa, Shamsul Rahman Mohamed Kutty, Sri Rahayu Mohd Hussin, Nurhidayati Mat Daud, Amirhossein Malakahmad
    The presence of heavy metals in aquatic systems has become a serious problem. Heavy metals can haveadverse effects on the environment as well as on human health. As a result, much attention has beengiven to new technologies for removal of heavy metal ions from contaminated waters. In this study,Microwave Incinerated Rice Husk Ash (MIRHA), a locally available agricultural waste, was used for theremoval of Cd (as a representative heavy metal) from synthetic wastewater by batch adsorption process.The effects of pH, initial metal concentration, and contact time on Cd removal efficiency were studied.pH 4 was found to be the optimum. The removal efficiency was found to be correlated with the initialmetal concentration and contact time between adsorbent and adsorbate. Cd adsorption kinetics followedthe pseudo-second-order model and implied chemisorption. The adsorption equilibrium of Cd can bewell described by the Freundlich isotherm model.
  16. Ferra Naidir, Robiah Yunus, Tinia Idaty Mohd. Ghazi, Irmawati Ramli
    Palm oil-based Trimethylolpropane ester (TMP ester), with an iodine value of 66.4 g/100g, was epoxidizedto produce epoxidized TMP esters. In situ epoxidation method was used with peracetic acid to eliminatefatty acid double bonds in palm oil-based TMP ester and change it into oxirane ring. This was done toimprove the oxidative stability of trimethylolpropane ester which is a key concern limiting the usefulservice life in lubricants. The epoxidation was performed by reacting acetic acid as active oxygen carrierwith concentrated hydrogen peroxide as oxygen donor and a small amount of homogeneous catalyst(sulphuric acid). The effects of various parameters on the rate of epoxidation (such as the ratio of moleacetic acid to ethylenic unsaturation, hydrogen peroxide to ethylenic unsaturation and acetic acid moleratio, and amount of catalyst) were studied. The rate of oxidation was investigated by the percentageof oxirane oxygen analysis and iodine value.
  17. Siti Aslina Hussain, Tan, Hong Tat, Mohd Ismail Abdul Hamid, Norhafizah Abdullah, Azni Idris
    Numerical studies of blood flow system of aorta coronary sinus conduit were carried out using ANSYSTMCFD simulation. A different model of conduit, which differs in the inlet diameter, was investigated. Theinvestigated inlet diameters are 3 mm, 4 mm and 5 mm. Pressure drop from 80 mmHg to 15 mmHgwas achieved for all the models. The comparison chart was produced to compare the pattern of pressurereduction as well as velocity distribution in each model. From the analysis of coronary sinus conduit,it was found that a narrow tube needs to be incorporated into the conduit produced. This is to inducea venturi effect to reduce the pressure drop of blood within a specific throat length. As conclusion, amodel of 3 mm inlet and a throat diameter of 1.13 mm show satisfactory result for pressure reductionfrom 80 mmHg to 15 mmHg. This particular model also has a lower peak velocity at the inlet zone ofthe throat section, which is more preferable in terms of Reynolds number.
  18. Siregar, J.P., Sapuan, S.M., Rahman, M.Z.A., Zaman, H.M.D.K.
    A study on the effects of alkali treatment and compatibilising agent on the tensile properties of pineappleleaf fibre (PALF) reinforced high impact polystyrene (HIPS) composite is presented in this paper. Thetensile properties of natural fibre reinforced polymer composites are mainly influenced by the interfacialadhesion between the matrix and the fibres. In this study, several chemical modifications were employedto improve the interfacial matrix-fibre bonding and this resulted in the enhancement of tensile propertiesof the composites. In this study, the surface modification of pineapple fibre with alkali treatments andcompatibilizer were used to improve the adhesion between hydrophilic pineapple fibre and hydrophobicpolymer matrix. There are two concentrations of NaOH treatments and compatibilizer used in this study,namely, 2 and 4 wt. %. The results show that the alkali treated fibre and the addition of compatibilisingagent in PALF/HIPS composites have improved the tensile strength and tensile modulus of the composites.
  19. Mohd Khairol Anuar Mohd Ariffin, Masood fathi, Napsiah Ismail
    Assembly line balancing is well-known in mass production system but this problem is non-deterministicpolynomial-time(NP)-hard, even for a simple straight line. Although several heuristic methods havebeen introduced and used by researchers, knowing and using an effective method in solving these typesof problems in less computational time have a considerable place in the area of line balancing problem.In this research, a new heuristic approach, known as critical node method (CNM), was introduced andtested by solving several test problems available in the literature so as to solve straight assembly lines.Finally, the obtained results are compared with 9 other heuristic rules in some performance measures.Thus, it is concluded that the proposed CNM is better than the rest in all the measures.
  20. Nasiman Sapari, Raja Zainariah Raja Azie, Hisyam Jusoh
    Hard rock formations consisting of granite and metasedimentary rocks in Peninsular Malaysia, have beenconsidered to be of poor aquifers. The map of shows the area underlain by hard rock as having poorto moderate potential for groundwater production (
Contact Us

Please provide feedback to Administrator (tengcl@gmail.com)

External Links