Browse publications by year: 2016

  1. Noppakun T, Wuttichai S, Angkana B
    Sains Malaysiana, 2016;45:1565-1572.
    This study involves testing the equality of several normal means under unequal variances, which is the setup of one-way analysis of variances (one-way ANOVA). Several tests are available in the literature, however, most of them perform poorly in terms of type I error rate under unequal variances. In fact, Type I errors can be highly inflated for some of the commonly used tests, a serious issue that seems to have been overlooked. Even though several tests have been proposed to overcome the problem, most of them show difficulty in calculation. Accordingly, the test for ANOVA with estimation of parameters using Bayesian approach is proposed as an alternative to such tests. The proposed test is compared with four existing tests such as the original test, James’s test, Welch’s test and the parametric bootstrap (PB) test. Type I error rates and powers of the tests are evaluated using Monte Carlo simulation. Our results indicated that the performance of the proposed test is superior to the original test and is comparable to James’s test, Welch’s test and the PB test, controlling Type I error rate quite well and showing high power of the test. Our study suggested that the proposed test has high performance and should be used as an alternative to the four existing tests due to its simple formula.
  2. Bashir U, Jamaludin Md. Ali
    Sains Malaysiana, 2016;45:1557-1563.
    This study was concerned with shape preserving interpolation of 2D data. A piecewise C1 univariate rational quadratic trigonometric spline including three positive parameters was devised to produce a shaped interpolant for given shaped data. Positive and monotone curve interpolation schemes were presented to sustain the respective shape features of data. Each scheme was tested for plentiful shaped data sets to substantiate the assertion made in their construction. Moreover, these schemes were compared with conventional shape preserving rational quadratic splines to demonstrate the usefulness of their construction.
    MeSH terms: Algorithms
  3. Liu QJ, Liu ZT
    Sains Malaysiana, 2016;45:1551-1556.
    The first-principles calculations were performed to investigate the structural, elastic, mechanical and electronic properties of α-Al2O3 at applied pressure up to 50 GPa. The obtained ground state properties were in agreement with previous experimental and theoretical data. The elastic constants, bulk modulus, shear modulus, Young’s modulus and anisotropy have been calculated as pressure increased. It was found that there was a brittle-ductile transition at about 23.2 GPa. The increasing ratio Ba /Bc with pressure indicates the weakening chemical bonding and the increasing anisotropy in this compound. The electronic structures were also calculated, which shows that band gaps increase monotonically. The population analysis showed the charge transfer was mainly between Al-3s and O-2p as pressure increased.
  4. Tang X, Yang Y, Xie Y
    Sains Malaysiana, 2016;45:1543-1550.
    The main objective of this work was to investigate the influence of waterborne epoxy resin emulsion (WER) on the physical properties of oil well cement slurries. Cement slurries containing 5%, 10% and 15% of WER bwoc were compared with WER-free slurries. The rheological behavior was carried out according to API standard. Uniaxial compressive strength and shear bond strength of cement stone were evaluated at the ages of 24, 48 and 72 h. The experimental results illustrate that the addition of WER does not alter the rheological behavior. The addition of WER has increased the shear bond strength almost 52% at 24 h of aging for 10% WER bwoc when compared with unmodified slurry. The enhancement on shear bond strength was attributed to the mechanical anchoring and resin film forming at the interface
    MeSH terms: Dental Cements; Dental Cementum; Epoxy Resins; Glass Ionomer Cements; Compressive Strength; Oil and Gas Fields
  5. Herny Erdawati Mohd Rashed, S Maria Awaluddin, Noor Ani Ahmad, Nurul Huda Md Supar, Zubidah Md Lani, Fauziah Aziz, et al.
    Sains Malaysiana, 2016;45:1537-1542.
    Various factors may contribute to adverse pregnancy outcomes; either maternal or foetal outcomes. This study aimed was
    to determine the association between advanced maternal age and adverse pregnancy outcomes. This is a cross sectional
    study. Data were collected from the birth records from January 1st 2012 until December 31st 2012 in Muar District.
    Descriptive and multiple logistic regression analyses were done and the results were presented as adjusted odds ratio
    (aOR) with p-value <0.05. The proportion of birth in Muar district, Johor was 14.8% among mothers aged 35 years
    and older and 85.2% among mothers aged 20 to 34 years. Advanced maternal age was associated with pregnancyinduced
    hypertension (aOR: 5.00; 95%CI: 1.95-12.65), gestational diabetes mellitus (aOR: 2.32; 95%CI: 1.35-4.00)
    and Caesarean section (aOR: 2.21; 95%CI: 1.53-3.19). Anaemia was negatively associated with advanced maternal
    age (aOR: 0.50; 95%CI: 0.32-0.78). No significant association was found between advanced maternal age and adverse
    foetal outcomes. In view of the findings, special attention should be paid to the antenatal mothers aged 35 years and
    older, even to those without any pre-existing medical problems.
    MeSH terms: Anemia; Attention; Birth Certificates; Cesarean Section; Cross-Sectional Studies; Female; Humans; Hypertension; Maternal Age; Mothers; Pregnancy; Pregnancy Outcome; Prenatal Care; Logistic Models; Odds Ratio; Diabetes, Gestational; Parturition
  6. Mohamad Shariff A Hamid, Arshad Puji, Zakiy Jamalullail, Zaidi Salleh, Kamarul Hashimy Hussein
    Sains Malaysiana, 2016;45:1531-1536.
    Although more Malaysians are taking part in International Multisport Games, these athletes well-being at such events have not been fully explored. The purpose of this study was to examine the pattern of injury and illness among Malaysian athletes during the XVII Asian Games 2014. Clinical and socio-demographic information of athletes diagnosed with injury or illness during the centralised training camp and at the Games were recorded in a standardised report form. Throughout the study period, 83 injuries and 64 illnesses were recorded from 276 athletes. Muscle strains and tears were the most common injury followed by ligamentous injury and soft tissues contusion. The number of injuries was highest among badminton players followed by hockey and rugby. Significantly higher incidence of injuries was observed among men than women hockey players. Athletes in individual events had higher proportion of more severe injury than those in team events. Respiratory tract infection was the most frequent illness diagnosed among athletes. Most injuries and illnesses diagnosed among athletes were minor and did not result in time away from participation. The incidence of injuries and illnesses among Malaysian athletes at the XVII Asian Games were comparable with those reported by previous authors. Injury and illness rate were influenced by gender and sports. Fortunately, majority of injuries and illnesses were minor and did not prevent athletes from participation.
    MeSH terms: Contusions; Female; Football; Hockey; Humans; Male; Respiratory Tract Infections; Sprains and Strains; Racquet Sports; Incidence; Athletes
  7. Ahmad Nazlim Yusoff, Khairiah Abdul Hamid, Hamdi Hamzah, Mazlyfarina Mohamad, Siti Zamratol-mai Sarah Mukari, Wan Ahmad Kamil Wan Abdullah
    Sains Malaysiana, 2016;45:1525-1530.
    High sensitivity signal detection for a sparse temporal sampling (STS) functional magnetic resonance imaging (fMRI) is compensated by the increase in the number of scans (Ns) and consequently the scan time. A long scan time would result in fatigue and restlessness in participants, while a short scan time is undesirable for an STS-fMRI due to insufficient Ns for averaging. The purpose of this study was to determine the Ns practically sufficient for a sparse fMRI study. Eighteen participants were presented with white noise during a sparse fMRI scan. The height extent of activation was determined via t statistics and region of interest (ROI) based percentage of signal change (PSC). The t statistics and PSC for Heschl’s gyrus (HG) and superior temporal gyrus (STG) during which the participants listened to the white noise were calculated for different number of scans which were 6, 12, 18, 24, 30 and 36. The t statistics and PSC values calculated for the bilateral HG and STG qualitatively indicated a minimal change over Ns = 12 to 36. Both ROIs showed a consistent common right lateralization of activation for all Ns, indicating the right-hemispheric dominance of auditory cortex in processing white noise stimulus. It was proposed that for a sparse fMRI study, Ns may practically fall between 12 and 36
  8. Khan SH, Ali F, Shah A, Kamran F, Jahan S
    Sains Malaysiana, 2016;45:1517-1523.
    The present study was aimed at evaluating antihyperglycemic and antihyperlipidemic activity of nuciferin and
    norcoclaurine constituents of N. nucifera seeds, a well-known medicinal plant. The alloxan (100 mg/kg b.w) induced
    diabetic rats (200-250 g) were divided into seven groups (n = 6). Group I; normal control, Group II; diabetic control,
    Group III; standard, Group lV-VII were fed with methanolic crude extracts (100, 200 mg/kg), nuciferin and norcoclaurine
    (10 mg/kg b.w.), received for 15 days in dose dependent manner. The study included different parameters; examination of
    oral glucose, fasting blood glucose, serum lipid profile and checking for body weight changes. In oral glucose examination,
    within 60 and 80 min of treatment, extracts, nuciferin and norcoclaurine significantly reduced blood glucose (p<0.05)
    and restored body weight in diabetic rats. Alloxan- induced diabetic rats showed 30-50% reduction of blood glucose
    level (p<0.05) and recovered 5-20% body weight at day 15 after ingestion of crude extracts (100-200 mg/kg b.w.); and
    nuciferin and norcoclaurine (each at 10 mg/kg b.w.). It also recovered significantly elevated biochemical parameters such
    as triglycerides (TG), low density lipoprotein (LDL), high density lipoprotein (HDL), total cholesterol (TC), serum urea and
    creatinine. Our findings indicated that N. nucifera seeds possess significant antihyperglycemic and antihyperlipidemic
    activity in diabetic rats.
    MeSH terms: Methanol; Alkaloids; Alloxan; Animals; Hypolipidemic Agents; Blood Glucose; Body Weight; Cholesterol; Creatinine; Diabetes Mellitus, Experimental; Fasting; Glucose; Hypoglycemic Agents; Lipoproteins, HDL; Lipoproteins, LDL; Plants, Medicinal; Seeds; Triglycerides; Urea; Tetrahydroisoquinolines; Complex Mixtures; Rats
  9. Shehzad MA, Maqsood M, Abbas T, Ahmad N
    Sains Malaysiana, 2016;45:1497-1507.
    Boron (B) is a mineral considered essential for improving sunflower (Helianthus annuus L.) resistance to drought. B supplements (0, 15-, 30- and 45 mg L-1) under well-watered and variable water deficit levels (64 and 53 mm irrigation depths) were evaluated for their effects on growth, oil quality and water use efficiency (WUE) in a field study for two consecutive years (i.e. 2011 and 2012). The duration of 50% inflorescence emergence, 50% flowering and 50% maturity stages were reduced with increasing moisture stress. All B application rates improved sunflower growth compared to no B control treatment. The moisture deficit treatments of 64 and 53 mm irrigation depths significantly (p<0.05) reduced the yield-related components. Achenes/head, achenes weight and achene yield under water stress conditions were considerably improved by foliar application of B at 30 mg L-1. An increase in protein contents and a decrease in oil contents were observed with B foliar application under moisture deficit treatments. Foliar application of B (30 mg L-1) on water stressed plants also resulted in increased WUE. The highest net benefits were achieved with B concentration of 30 mg L-1 under well-watered and mild deficit water level of 64 mm irrigation depth. The highest application rate of B (45 mg L-1) gave the best results at the most severe water deficit level. In conclusion, the B rates of 30 and 41 mg L-1 performed best for improving drought tolerance in terms of higher sunflower productivity under mild and higher water deficit conditions
    MeSH terms: Body Weight; Boron; Dehydration; Helianthus; Minerals; Water; Dietary Supplements; Droughts; Inflorescence; Water Wells
  10. Mat Esa Mohd Ikhwanuddin, Mohammad Noor Azmai Amal, Shamarina Shohaimihasrul, Hazman Hasan, Nor Rohaizah Jamil
    Sains Malaysiana, 2016;45:1487-1495.
    This study evaluates the current environmental influences on fish assemblages of the upper Sungai Pelus, Kuala Kangsar, Perak. Fish samplings and habitat characterizations were conducted at three significant different months, which were on dry (June 2014), wet (August 2014) and moderately wet seasons (April 2015). A total of 510 individual fish were collected from the study, which consist of four orders, nine families, 20 genus and 21 species of fishes. Cyprinidae was the biggest family, followed by Bagridae, Balitoridae and Sisoridae. Neolissochilus hexagonolepis was the only species documented under the nearly threatened list, even their individual number and occurrences were the highest recorded. The readings of environmental variables, such as water temperature, pH, conductivity, dissolved oxygen, total dissolved solids, biological oxygen demand and total suspended solids were regarded as normal for upper river area. However, the water turbidity and chemical oxygen demand (COD) were quite high, which we believed was due to seasonal variation and current anthropogenic activities of the nearby river area. Canonical correspondence analysis showed that the water conductivity, river width, COD and water velocity were the main factors in influencing the fish assemblages of this upper Sungai Pelus. The findings can be utilized as a guideline to manage, protect and conserve this upper river area in the near future.
    MeSH terms: Animals; Climate; Cyprinidae; Oxygen; Seasons; Temperature; Water; Ecosystem; Rivers; Biological Oxygen Demand Analysis
  11. Phatai P, Srisomang R
    Sains Malaysiana, 2016;45:1477-1485.
    In this study, the adsorption efficiency of methyl violet (MV) dye onto Ce0.3Al0.7 and Ce0.3Al0.7Agx (x = 0.1, 0.3 & 0.5) mixed oxides was investigated. The properties of mixed oxide were determined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), N2 adsorption-desorption isotherm, diffuse reflectance UV-vis spectroscopy (UV-vis DRS) and X-ray absorption near edge structure (XANES). Characterization showed that synthesized mixed oxide with fluorite has a pure cubic structure of a mesoporous nature and a small grain size with rough surface. Batch adsorption experiments were used to study parameters including contact time and initial dye concentration. The results showed that these parameters affected the degree of MV dye adsorption. The dye adsorption of mixed oxides attained equilibrium at 120 min. The equilibrium adsorption data were analyzed using Langmuir, Freundlich and Temkin isotherms. The adsorption behavior of MV dye onto Ce0.3Al0.7 was found to follow the Langmuir isotherm (R2 = 0.9951), providing a maximum monolayer adsorptive capacity of 2.35 mg/g. Alternatively, the adsorption of MV dye onto Ce0.3Al0.7Ag0.1 (R2 = 0.7839), Ce0.3Al0.7Ag0.3 (R2 = 0.9301) and Ce0.3Al0.7Ag0.5 (R2 = 0.9396) followed the Freundlich isotherm. The possible adsorption mechanisms of MV dyes onto the Ce0.3Al0.7 and Ce0.3Al0.7Agx were also discussed.
    MeSH terms: Adsorption; Azo Compounds; Coloring Agents; Gentian Violet; Microscopy, Electron, Scanning; Oxides; Spectrometry, X-Ray Emission; X-Ray Diffraction; X-Rays; Spectroscopy, Fourier Transform Infrared; Plant Structures
  12. Haliru Musa, Bolanle BB, Farizul Hafiz Kasim, Arbain D
    Sains Malaysiana, 2016;45:1469-1476.
    Polyhydroxybutyrate (PHB) otherwise known as bioplastics are biodegradable materials that are accumulated in various microorganisms to serve as carbon and energy reservoirs and regarded as an attractive alternative to petroleum-derived plastics. Although research has been conducted on isolation of PHB-producing microorganisms from different ecological environments, few studies have been carried out on isolation of potential PHB-producing microorganisms from rhizosphere environment of groundnut plants, Arachis hypogaea which can be regarded as a good environment for the isolation of potential PHB-producing microorganisms. In the present study, a total of twenty-one (21) bacterial strains were primarily screened and isolated from rhizosphere soil of a groundnut plant. Four bacterial isolates with maximum PHB-producing potential upon screening using submerged fermentation were selected for further studies. The fermentation pattern of PHB production was studied using different nutrient sources. The influence of agitation on PHB production was also studied. Mannitol stimulated maximum (6.076a mg/mL) PHB production by Bacillus sp. 1; KNO3 used as a limiting nutrient induced best (5.728a mg/mL) PHB production by Citrobacter sp. and MgSO4.7H2O supported maximum (5.972a mg/mL) PHB production in Enterococcus sp. A low agitation speed of 150 rpm was found to support best (5.802a mg/mL) PHB production by Bacillus sp.1. Findings from this study indicated that the isolated bacterial strains have high PHB- producing potential. The need to explore other environment harbouring microbial strains with high PHB-producing potential is paramount to the discovery of bioplastics with improved properties for potential industrial applications.
    MeSH terms: Bacillus; Bacteria; Carbon; Citrobacter; Environment; Fermentation; Food; Mannitol; Arachis; Petroleum; Plastics; Soil; Enterococcus; Rhizosphere
  13. Panchal BM, Deshmukh SA, Sharma MR
    Sains Malaysiana, 2016;45:1461-1468.
    The transesterification of Thevetia peruviana seed oil with dimethyl carbonate (DMC) for preparing biodiesel has been studied using as an active catalyst potassium-methoxide (KOCH3). The effects of reaction conditions: Molar ratio of dimethyl carbonate to Thevetia peruviana seed oil, catalyst concentration, reaction time and agitation speed on dimethyl esters (DMC-Tp-BioDs) yield were investigated. The highest DMC-Tp-BioDs yield could reach 97.1% at refluxing temperature for 90 min with molar ratio of DMC-to-oil 5:1 and 2.0% w/w KOCH3 (based on oil weight). The fuel properties of the produced DMC-Tp-BioDs were compared with the ASTM D6751-02 biodiesel standard.
    MeSH terms: Catalysis; Esterification; Esters; Formates; Potassium; Reaction Time; Seeds; Temperature; Thevetia; Biofuels
  14. Saw HL, Yu TC, Khairun Nisa Nor Afindi, Norshima Abdullah Kamaruddin
    Sains Malaysiana, 2016;45:1453-1459.
    A simple and fast dispersive liquid-liquid microextraction (DLLME) technique using organic solvent lighter than water has been developed for the extraction of selected polycyclic aromatic hydrocarbons in green tea, chrysanthemum tea and coffee beverage. The 1-octanol and acetonitrile were pre-mixed and injected into the sample solution. After dispersing, the cloudy solution was subjected to centrifugation to separate the solution into 2 phases, where the micro-droplet of 1-octanol was clearly floated on the top layer. The 1-octanol extract was then diluted and injected into high performance liquid chromatography-fluorescence for the quantitative analysis. The technique offered rapid analysis as the 1-octanol was homogeneously dispersed in the sample solution thus speeding the analytes diffusion. Under the optimized extraction conditions, the technique achieved trace detection limits in the range of 0.001 to 0.3 μgL-1 for the targeted analytes, namely phenanthrene, fluoranthene and benzo[a]pyrene. The method was successfully applied to the spiked green tea, chrysanthemum tea and coffee beverage samples with good average relative recoveries obtained in the range of 86.7 to 103.0%. The utilization of low density organic solvent as extraction solvent has allowed for easier operation and eliminated the use of hazardous halogenated solvent that is commonly applied in DLLME.
  15. Ul Haq MN, Wazir SM, Ullah F, Khan RA, Shah MS, Khatak A
    Sains Malaysiana, 2016;45:1435-1442.
    In this study, the antimicrobial, antioxidant, phytotoxic and phytochemical properties of defatted seeds of Jatropha curcas were evaluated. A crude methanolic extract of defatted seeds was tested against three fungal strains - Aspergillus niger, Aspergillus flavus and Aspergillus fumigatus - and five bacteria: Escherichia coli and Klebsiella pneumoniae (Gram negative) and Micrococcus luteus, Bacillus subtilis and Staphylococcus aureus (Gram positive). The methanolic extract was diluted in dimethylsulfoxide to final concentrations of 1, 2, 3, 4 and 5 mg/10 mL. The largest zones of inhibition against K. pneumoniae, M. luteus and B. subtilis were achieved using the concentration of 5 mg/10 mL. The concentration of 1 mg/10 mL was most effective against S. aureus and E. coli. In a 1, 1-diphenyl-2-picrylahydrazyl (DPPH) radical scavenging assay, the 5 mg/10 mL concentration of the Jatropha seed extract showed the strongest activity. Higher concentrations of the Jatropha seed extract (10 mg/50 mL and 5 mg/50 mL) significantly inhibited the germination of radish seeds and had negative effects on radish seedling relative water content, shoot length, root length, seedling fresh weight and seedling dry weight (p<0.05). Phytochemical analyses of the defatted seeds detected alkaloids (7.3%), flavonoids (0.39%) and soluble phenolics (mg gallic acid equivalents/g extract). Based on these results, it was inferred that J. curcas seeds contain active ingredients that are effective against pathogenic microbes and therefore could be used to formulate drugs to treat various diseases.
    MeSH terms: Methanol; Alkaloids; Anti-Infective Agents; Anti-Bacterial Agents; Antioxidants; Aspergillus flavus; Aspergillus fumigatus; Aspergillus niger; Bacillus subtilis; Biphenyl Compounds; Dimethyl Sulfoxide; Escherichia coli; Flavonoids; Gallic Acid; Klebsiella pneumoniae; Seeds; Staphylococcus aureus; Water; Micrococcus luteus; Germination; Raphanus; Jatropha; Seedlings; Phytochemicals
  16. Khoirun Nisa Mahmud, Maizatulakmal Yahayu, Siti Hajar Md. Sarip, Nurul Husna Rizan, Chai BM, Nurul Farhana Mustafa, et al.
    Sains Malaysiana, 2016;45:1423-1434.
    Generation of huge volumes of lignocellulosic biomass from agricultural sector is of concern due to its direct effects on the depletion of overall environmental quality. Conversion of biomass into solid biofuel through pyrolysis reaction has become one of the solutions to manage the abundance of biomass. Pyroligneous acid (PA) produced from the condensation of smoke generated during biomass carbonization process has the potential to be applied in various applications based on the diverse active chemical compounds present. In this study, PA obtained from palm kernel shell (PKS) was evaluated for antifungal activity and solid pineapple biomass (PB) was evaluated for antibacterial and plant growth promoter activities. Higher antifungal activity was determined for crude PA from PKS (PA-PKS) and dichloromethane-extract (DPA-PKS) with 0% coverage area when evaluated using rubber wood blocks against mold and blue sapstain after for 4 weeks of observation. This antifungal activity can be attributed to the presence of phenols and its major derivatives as suggested from the GC-MS and FTIR analysis. Concentrated PA from PB displayed good antibacterial capabilities with almost similar growth inhibition for Escherichia coli (13±1 to 20±1 mm) and Corynebacterium agropyri (20±1 mm). PA-PB also showed good potential as PGP where the addition of 2% (v/v) of PA-PB into the fertilizer for okra plant resulted in highest number of leaves and fruits while 4% (v/v) PA-PB managed to give highest plant height, longest root, heaviest fruits and biggest leaf diameter. Thus, this study successfully demonstrated the potential use of PA obtained from lignocelluosic biomass in various applications.
  17. Noor Azrizal-Wahid, Mohd Sofian-Azirun, Mohammed Rizman- Idid
    Sains Malaysiana, 2016;45:1413-1422.
    ix species of Eurema butterflies comprised of 261 adult individuals collected from various sampling sites in Peninsular Malaysia were identified. The morphometric measurement of the specimens was carried out by using seven characters measured from the wing and body regions. Morphometric analysis was determined through the multivariate analysis of Discriminant Function Analysis (DFA) and Cluster Analysis. The results of DFA showed that two out of seven characters utilized have the lowest values of Partial’s Wilks Lambda; basal length and hindwing length. These characters therefore are significant for the discrimination of the Eurema species. The classification matrix shows that both E. hecabe and E. blanda were completely discriminated by the characters set. Moreover, there was great overlaps occurred between the species groups when plotting a conical graph except for species E. blanda that formed homogenous group. Basal length was also suggested as the species-specific character for grouping the species E. blanda. In Cluster Analysis, E. hecabe tends to be closer to E. sari with the lowest value of agglomeration. The results from dendogram generated from average linkage also showed several relationship patterns among the six species.
  18. Maria Abu Bakar, Azman Jalar, Abdul Razak Daud, Roslina Ismail, Nur Azida Che Lah, Najib Saedi Ibrahim
    Sains Malaysiana, 2016;45:1275-1279.
    This work investigates the micromechanical properties of Sn96.5Ag3.0Cu (SAC 305) on Immersion Tin (ImSn) surface
    finished after subjected to high temperature storage (HTS) at 180°C for 200 to 1000 h period. Nanoindentation approach
    was used to measure the micromechanical properties of the solder. It was observed that the indentation depth and plastic
    depth were increased and a clear trend of decreasing hardness as opposed to the increasing reduced modulus as the HTS
    time lengthened. The plasticity-asscociated properties become stronger meanwhile the elasticity-associated properties
    decreased with the HTS time. These findings indicate that nanoindentation approach can clearly determine the plastic
    and elastic deformation occurance throughout the test.
  19. Norinsan Kamil Othman, Solhan Yahya, Denni Asra Awizar
    Sains Malaysiana, 2016;45:1253-1258.
    Anticorrosive properties of nano silicate from paddy husk in salt medium was investigated via weight loss method, Tafel
    polarization and impedance techniques. Prior to the corrosion test, the silica powder was obtained from burning the
    rice husk and extended with a chemical treatment process. The size of silica powder was characterized via zeta sizer and
    showed the amount of micro silica particle appear more than the nano size particle. Nano silica powder was produced
    from the refluxing process of micro silica to enhance the good properties of silica particle. The corrosion inhibition
    efficiency of nano silicate showed good inhibition with increased in inhibitor concentrations. Weight loss test exhibits
    high inhibition as more than 80% even, immersed in the corrosive medium until 14 days. The nano silicate inhibitor
    affected the anodic reaction as showed by Tafel plot analysis. Impedance results also correlated with other test as shown
    by the large size of Nyquist semicircle which represents as high resistance of charge transfer. The surface morphology
    of inhibited specimen showed a smooth surface after nano silicate inhibitor applied in the NaCl medium as observed
    through scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX).
    MeSH terms: Corrosion; Microscopy, Electron, Scanning; Particle Size; Oryza; Silicon Dioxide; Sodium Chloride; Spectrometry, X-Ray Emission; X-Rays; Weight Loss; Electric Impedance; Silicates
  20. Wan Nasarudin Wan Jalal, Huda Abdullah, Mohd Syafiq Zulfakar, Badariah Bais
    Sains Malaysiana, 2016;45:1243-1252.
    Kaedah sol gel digunakan untuk menghasilkan filem nipis CoxZn(1-x)Al2
    O4 berstruktur nano pada suhu 600°C. Corak
    pembelauan XRD menunjukkan pembentukan struktur tunggal spinel ZnAl2
    O4 dan CoAl2
    . Saiz hablur dan ketumpatan
    bahan berkurangan apabila kepekatan bahan dopan Co bertambah, iaitu masing-masing daripada 19.52 kepada 10.39 nm
    dan 4.609 kepada 4.585 g/cm3
    . Parameter kekisi pula meningkat daripada 8.085 kepada 8.098 Å apabila Co meningkat.
    Analisis FTIR menunjukkan ikatan ZnO, Co dan Al-O berlaku antara 487 hingga 550 cm-1, manakala ikatan spinel bagi
    dan CoAl2
    pula terbentuk pada 655 cm-1. Imej AFM menunjukkan kekasaran permukaan menurun apabila Co
    bertambah iaitu daripada 30.21 nm (×=0.00) kepada 14.83 nm (×=0.30). Nilai pemalar dielektrik (εr
    ) menunjukkan
    penurunan secara linear apabila Co meningkat iaitu daripada 8.53 kepada 7.31. Seterusnya, GPS antena difabrikasi
    menggunakan sampel CoxZn(1-x)Al2
    . Prestasi dan frekuensi operasi GPS antena diukur menggunakan penganalisis
    rangkaian siri PNA pada frekuensi kenaan 1-2 GHz. Analisis mendapati antena beroperasi pada frekuensi 1.570 Ghz
    dengan kerungian pulangan -15.6 hingga -21.2 dB dan lebar jalurnya pula adalah 80 hingga 315 MHz. Kesemua antena
    yang telah difabrikasi memenuhi keperluan minimum antena untuk beroperasi pada aplikasi GPS.
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