Displaying publications 81 - 100 of 2561 in total

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  1. Ang B, Amalina M, Bong C, Ahmad N
    Sains Malaysiana, 2018;47:157-168.
    Nanosilver particles (NSPs) were produced by the reduction of silver nitrate using glucose as reducer, poly (vinyl pyrrolidone) as stabilizer and sodium hydroxide as reaction enhancer. Two parameters were investigated which are silver nitrate concentration (0.1 M, 0.5 M and 1.0 M) and reaction temperature (60°C and 80°C). Through spectral analysis using ultraviolet-visible spectrophotometer (UV-vis), all the samples recorded the maximum peak in the range of 384-411 nm which verified the formation of NSPs. TEM images showed the nanoparticles have spherical shape with the size range of 25-39 nm. Particle size and zeta potential analysis recorded the hydrodynamic size of nanoparticles in the range of 85-105 nm and the zeta potential ranging from -25 to -30 mV, under the pH value of 8. X-ray diffraction analysis showed that the NSPs have face center cubic (FCC) structure. All the produced NSPs surprisingly showed ferromagnetic-like behaviour based on the magnetization curves. FTIR result confirmed the presence of poly (vinyl pyrrolidone) on the NSPs surface. Furthermore, at the reaction temperature 60°C, the crystallite size, physical size as well as hydrodynamic size increased as the precursor concentration increased from 0.1 M to 0.5 M. However, as the precursor concentration further increases to 1.0 M, the size become smaller due to incomplete reduction process. In contrast, at 80°C, the sizes was gradually increased as the precursor concentration increases up to 1.0 M. In terms of controlled precursor concentration, the crystallite size and physical size become smaller as the temperature increases.
  2. Nitanan Koshy Matthew, Ahmad Shuib, Sridar Ramachandran, Syamsul Herman Mohammad Afandi, Zaiton Samdin, Ismail Muhammad, et al.
    Sains Malaysiana, 2018;47:447-455.
    Forest degradation and deforestation are some of the major global concerns as they can reduce the forest carbon stock
    and sequestration capacity. However, the carbon stock and sequestration potential in a mixed dipterocarp tropical forest
    remains unclear due to a lack of information. This study was carried out on the carbon stock and estimated its economic
    value to justify its conservation. Six plots were established in the Endau Rompin National Park, Johor and subplots
    measuring 50 × 20 m were established in each plot. All trees greater than 15 cm DBH (diameter at breast height) were
    identified and the parameters measured included tree height and diameter. The aboveground carbon (AGC) content was
    about 222 Mg(C) ha-1, belowground carbon (BGC) was 53 Mg (C) ha-1 and it was 6 Mg (C) ha-1 for other components.
    In total, the carbon stock amounted to 281 Mg (C) ha-1. On the other hand, the total CO2 sequestrated in the mixed
    dipterocarp forest amounted to 1,040 t CO2
    ha-1. The carbon value was estimated at RM32,240 t CO2
    ha-1 or $7,280 t CO2
    ha-1. Therefore, the study found that the dipterocarp forest should be preserved to mitigate greenhouse gas emissions.
  3. Ang KH
    Sains Malaysiana, 2018;47:471-479.
    In recent years, Malaysia has experienced quite a few number of chronic air pollution problems and it has become a
    major contributor to the deterioration of human health and ecosystems. This study aimed to assess the air quality data
    and identify the pattern of air pollution sources using chemometric analysis through hierarchical cluster analysis (HCA),
    discriminant analysis (DA), principal component analysis (PCA) and multiple linear regression analysis (MLR). The air
    quality data from January 2016 until December 2016 was obtained from the Department of Environment Malaysia. Air
    quality data from eight sampling stations in Selangor include the selected variables of nitrogen dioxide (NO2
    ), ozone (O3
    ),
    sulfur dioxide (SO2
    ), carbon monoxide (CO) and particulate matter (PM10). The HCA resulted in three clusters, namely low
    pollution source (LPS), moderate pollution source (MPS) and slightly high pollution source (SHPS). Meanwhile, DA resulted
    in two and four variables for the forward stepwise mode and the backward stepwise mode, respectively. Through PCA,
    it was identified that the main pollutants of LPS, MPS and SHPS came from industrial and vehicle emissions, agricultural
    systems, residential factors and natural emission sources. Among the three models yielded from the MLR analysis, it was
    found that SHPS is the most suitable model to be used for the prediction of Air Pollution Index. This study concluded that
    a clearer review and practical design of air quality monitoring network would be beneficial for better management of
    air pollution. The study also suggested that chemometric techniques have the ability to show significant information on
    spatial variability for large and complex air quality data.
  4. Farha Mizana Shamsudin, Shahidan Radiman, Yusof Abdullah, Nasri A. Hamid
    Sains Malaysiana, 2018;47:189-193.
    The purpose of this study was to investigate the effect of annealing to the hardness of high Y2O3-oxide dispersion strengthened (ODS) ferritic steels. The samples were prepared by mechanical alloying method followed by Cold Isostatic Pressing (CIP). After compaction process, the samples were sintered at 1100°C for 1 h in a tube furnace. The crystal structure and morphology of samples were analyzed by X-ray Diffraction (XRD) measurement and characterized by using field emission scanning electron microscope (FESEM), respectively. The hardness of samples was measured by using a micro-Vickers hardness tester with a load of 200 gf at annealing temperature of 600°C, 800°C and 1000°C, respectively. The Vickers hardness value (HV0,2) versus annealing temperature graph showed that the hardness of all samples started to decrease at temperature of 600°C due to grain growth. The hardness value of all samples (1Y and 5Y) identified at this annealing temperature is 855 HV0,2 and 808 HV0, 2, respectively.
  5. Varavut Tanamool, Piyorot Hongsachart, Wichai Soemphol
    Sains Malaysiana, 2018;47:481-488.
    Acetic acid bacteria (AAB) isolated from natural resources and fermented plant beverages were screened to produce
    1,3-dihydroxyacetone (DHA) from non-detoxified crude glycerol. Among them, the isolate NKC115 was identified as
    Gluconobacter frateurii and produced the highest amounts of DHA. Subsequently, the effects of growth-medium conditions
    (initial pH, crude glycerol concentration and nitrogen sources) on growth and DHA-production capability were examined.
    The results showed that the crude glycerol concentration increase to above 100 g/L suppressed growth and DHA production.
    The highest amount of DHA obtained was 27.50 g/L, from an initial crude glycerol concentration of 100 g/L. Meanwhile,
    an initial pH of 5.5-7.5 in the YPGc medium did not significantly affect the bacterial growth and DHA production. The
    optimal nitrogen source was peptone, with DHA production at 34.70 g/L. Furthermore, overexpression of the nhaK2 gene
    encoding for the Na+(K+)/H+ antiporter from Acetobactor tropicalis SKU1100 in G. frateurii NKC115 improved growth
    and increased the accumulation of DHA (37.25 g/L) from an initial crude glycerol concentration of 20%. These results
    indicated that the expression of this antiporter might maintain an optimal intracellular pH and concentration of Na+ or
    K+, leading to the cells’ ability to tolerate high concentrations of crude glycerol.
  6. Azman Jalar, Norinsan Kamil Othman, Emee Marina Salleh, Zaifol Samsu
    Sains Malaysiana, 2018;47:1251-1257.
    Keluli karbon amat mudah terkakis dalam pelbagai persekitaran terutamanya dalam keadaan berudara lembap dan suhu tinggi. Oleh sebab itu, permukaan keluli karbon perlu dilindungi dengan bahan atau logam yang mampu menangani serangan kakisan yang agresif dengan membentuk lapisan oksida dan lapisan antara logam yang bersifat pelindung. Kajian ini dijalankan untuk menentukan mikrostruktur permukaan dan kekerasan salutan aluminium (Al) tulen yang telah dihasilkan melalui teknik celupan panas. Celupan panas dalam leburan Al tulen dilakukan pada suhu berbeza untuk mendapatkan lapisan salutan yang optimum. Keputusan teknik celupan panas menunjukkan dua lapisan utama terhasil iaitu lapisan luar Al dan lapisan dalam aluminit (Fe-Al). Manakala lapisan dalam aluminida terdiri daripada dua lapisan yang berbeza iaitu lapisan nipis luar FeAl3 dan lapisan tebal dalam Fe2Al5. Keputusan daripada ujian mikrokekerasan Vickers menunjukkan bahawa nilai kekerasan lapisan aluminida meningkat dengan peningkatan suhu leburan Al manakala lapisan Al tidak menunjukkan sebarang perubahan yang ketara.
  7. Siti Zubaidah Hasan, Zuhailie Zakaria, Mohamed Rozali Othman, Muhammad Rahimi Yusop
    Sains Malaysiana, 2018;47:1547-1556.
    Mangan oksida (MnO2
    ) poros nano yang mempunyai morfologi lapisan nipis telah disintesis dan diaplikasikan sebagai
    penjerap pewarna sintetik komersial (remazol merah, eriokrom hitam dan metilena biru). Permukaan bahan silika
    alumina yang telah diubah suai dengan 3-aminopropiltrietoksisilana (APTES) digunakan dalam proses sonokimia pada
    suhu bilik dengan kehadiran 0.1 M kalium permanganat (KMnO4
    ) untuk menghasilkan komposit silika alumina-MnO2
    .
    Penyingkiran templat dijalankan untuk mendapatkan MnO2
    tulen bersaiz nano. Spektrum FTIR menunjukkan kehadiran
    getaran MnO2
    dalam julat 400 - 600 cm-1 dan corak XRD menunjukkan kehadiran birnesit jenis MnO2
    . Isoterma jerapnyahjerap
    N2
    menunjukkan MnO2
    tulen memiliki liang yang bersifat mesoporos iaitu 34.8 Å (± 0.4), manakala luas
    permukaan MnO2
    ialah 252.8 m2
    /g. Penjerap MnO2
    lapisan nipis yang diperoleh menunjukkan kebolehan menjerap
    pewarna eriokrom hitam dan metilena biru masing-masingnya sehingga 54% dan 99% serta kapasiti penjerapan masingmasing
    ialah 0.0024 dan 0.0077 mmol/g. Kedua-dua isoterma penjerapan eriokrom hitam dan metilena biru oleh MnO2
    masing-masing menepati ciri-ciri Langmuir dan Temkin. Sementara itu data kinetik penjerapan eriokrom hitam dan
    metilena biru kedua-duanya memenuhi tertib pertama pseudo.
  8. Marhaini Mostapha, Noorhasmiera Abu Jahar, Sarani Zakaria, Sharifah Nabihah Syed Jaafar, Kamalrul Azlan Azizan, Wan Mohd Aizat
    Sains Malaysiana, 2018;47:1259-1268.
    Oil palm is the major crop grown and cultivated in various Asian countries such as Malaysia, Indonesia and Thailand.
    The core of oil palm trunk (COPT) consists of high sugar content, hence suitable for synthesis of fine chemicals and
    biofuels. Increase of sugar content was reported previously during prolonged COPT storage. However, until now, there
    has been no report on protein profiles during storage. Therefore, in this study, protein expression of the COPT during the
    storage period of one to six weeks was investigated using sodium dodecyl sulphate polyacrylamide gel electrophoresis
    (SDS-PAGE) coupled with optical density quantification and multivariate analyses for measuring differentially expressed
    proteins. Accordingly, protein bands were subjected to tryptic digestion followed by tandem mass spectrometry (nanoLCMS/MS)
    protein identification. The results from SDS-PAGE showed consistent protein bands appearing across the biological
    replicates ranging from 10.455 to 202.92 kDa molecular weight (MW) regions. The findings from the principal component
    analysis (PCA) plot illustrated the separation pattern of the proteins at weeks 4 and 5 of storage, which was influenced
    mainly by the molecular weights of 14.283, 25.543, 29.757, 30.549, 31.511, 34.585 and 84.395 kDa, respectively. The
    majority of these proteins are identified as those involved in stress- and defense-related, disease resistance, as well
    as gene/protein expression processes. Indeed, these proteins were mostly upregulated during the later storage period
    suggesting that long-term storage may influence the molecular regulation of COPT sap.
  9. Liyana Mohd Ali Napia, Faizal Mohamed, Hur Munawar Kabir Mohd, Intan Syakeela Ahmad Bastamam, Shamellia Sharin, Norsyahidah Mohd Hidzir, et al.
    Sains Malaysiana, 2018;47:1235-1240.
    Unilamellar liposomes composed of dipalmitoylphosphatidylcholine (DPPC) were prepared by the reverse-phase
    evaporation method and extrusion through a polycarbonate membrane filter. Liposomes at 0.7 mg/mL lipid concentration
    in deionized water were exposed to gamma irradiation at a dose in the range 0.5 to 25 kGy. Gamma irradiation of
    liposomes resulted in the degradation of DPPC lipids into free fatty acids, lysophosphatidylcholine and 1,2-palmitoylphosphatidic
    acid (DPPA). The effect of gamma irradiation towards the physical stability of liposomes was investigated
    by means of dynamic light scattering (DLS), transmission electron microscopy (TEM) and zeta potential analysis. From
    the DLS analysis, no significant changes were observed in the hydrodynamic size of liposomes. TEM images indicate that
    the liposomes surface became smoother and rounder as higher irradiation doses were applied. Zeta potential analysis
    showed that gamma irradiation of DPPC liposomes at radiation doses as low as 0.5 kGy resulted in a drastic rise in the
    magnitude of the zeta potential. The results also demonstrate that gamma irradiation of liposomes suspension enhanced
    the overall stability of liposomes. Hence, it can be concluded that gamma irradiation on DPPC liposomes may potentially
    produce liposomes with higher stability.
  10. Safiyyah Shahimi, Wan Sakeenah Wan Nazri, Aminah Abdullah, Norrakiah Abdullah Sani, Sahilah Abd. Mutalib
    Sains Malaysiana, 2018;47:1535-1540.
    Genomic DNA of 13 fish (n=13) species consist of four freshwater which were catfish (Clarias gariepinus), shark catfish (Pangasius larnaudii), tilapia (Oreochromis mossambicus), perch (Lates calcarifer) and nine marine species which were black pomfret (Parastromateus niger), anchovy (Stolephorus commersonii), mabong (Rastrelliger kanagurta), red snapper (Lutjanus erythropterus), herring (Chirocentrus dorab), ray fish (Himantura gerrardii), sardine (Decapterus macrosoma), mackerel (Euthynnus affinis) and tuna (Thunnus tuna) were differentiated using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Seven endonucleases of AluI, BsaJI, HaeIII, HindIII, HinfI, MboI and MboII were examined for the ability to digest cyt b amplicon from each species. Genomic DNA of pork (Sus scrofa domestica) were differentiated from fishes by comparing the digestion patterns produced by similar amplified region and enzymes used. In the present study, it was demonstrated that fishes and pork DNA genome were successfully differentiated using all endonucleases except for HindIII. Thus, PCR-RFLP analysis was found useful for future pork DNA detection in fish products.
  11. Malina Jasamai, Nurul Hanis Samsudin, Norazrina Azmi, Endang Kumolosasi
    Sains Malaysiana, 2018;47:1221-1226.
    Durian or scientifically known as Durio zibethinus is one of the most well-known seasonal fruits in the Southeast Asia
    region. However, its safe consumption in individuals with hypertension is still controversial. This study was conducted
    to investigate the effect of durian on blood pressure of spontaneously hypertensive rat model. Four groups of rats (n=5)
    were fed with either a low dose durian (26 g/kg), a high dose durian (52 g/kg), sugar solution (8 mL/kg) which has
    similar sugar composition in the durian as placebo control, and distilled water as vehicle control (8 mL/kg) for 14 days.
    The durian doses for rats were obtained by converting from human doses. Baseline reading of blood pressure and heart
    rate were recorded before the first oral administration of durian. The blood pressure and heart rate were also measured
    1 h after the durian oral administration on day 1, 3, 7 and 14 of the experiment. In conclusion, durian fruit possessed
    an acute effect on the blood pressure of hypertensive rats but heart rate was unaffected. High dose administration of
    durian led to significant elevation of blood pressure after 1 h of consumption. Meanwhile, low dose of durian (26 g/kg)
    caused an insignificant reduction in systolic and diastolic blood pressure. Tolerance to the durian fruit was observed after
    three to seven days of the oral administration and low dose consumption of durian fruit was safe in the hypertensive rat.
  12. Siti Nurul Ain Saipullizan, Razalee Sedek, Sahilah Abd. Mutalib
    Sains Malaysiana, 2018;47:1527-1533.
    This study aimed to evaluate the level of knowledge, attitude and practice (KAP) amongst food handlers in food utensils
    hygiene and presence of bacterial contamination on food utensils. There were two approaches used in this study. In the
    first approach, 134 of food handlers from 75 food premises were interviewed via questionnaires to assess their knowledge,
    attitude and practice. In the second approach, the presence of Staphylococcus aureus, Escherichia coli and total coliform
    of 225 utensils (knives (75), chopping boards (75) and dish plates (75)) was examined. The result showed that the food
    handlers had sufficient level of knowledge (80.5%), attitude (87.4%) and practice (90.1%). Highest contamination was
    found on the chopping boards for the presence of S. aureus (82.8%), E. coli (9.7%) and total coliform (73.9%). Logistic
    regression analysis showed that knowledge contributes to the presence of E. coli on the dish plates; and total coliform
    on the knives. Thus, ongoing training that focused on food utensils hygiene must be emphasized to improve knowledge,
    attitude and practice amongst the food handlers.
  13. Rosmawati Dora, Hasnah Haron, Muhamad Fikri Mohd Fauzi, Suzana Shahar, Chong CP, Mohd Fairulnizal Md Noh
    Sains Malaysiana, 2018;47:1557-1562.
    This study was conducted to determine the content of macronutrients and sugar in 30 types of food selected from three
    zones in Peninsular Malaysia. The food samples consisted of 14 types of processed foods and beverages, 8 types of
    fruits and 10 types ready to eat food. Each type of food and drink were purchased from selected restaurants, stores and
    supermarkets from three different zones which were North zone (Perak), Central zone (Selangor) and South Zone (Johor).
    Methods used for proximate analysis were based on the standard methods of AOAC (1997) while the total carbohydrate
    was calculated by difference method. Total calories were calculated using Atwater method. Total sugar content were
    analysed using high performace liquid chromatography (HPLC). Dietary fibre contents were determined by using a
    combination of enzyme-gravimetric methods (AOAC 985.29 and AACC 32-05). The results showed that peanut butter has
    the highest value of fat (44.75 ± 7.59 g/100 g), total calorie (611 ± 38 kcal /100 g) and dietary fibre contents (8.07 ± 0.98
    g/100 g). Highest protein content (21.98 ± 2.57 g/100 g) was found in low-fat milk powder. The highest carbohydrate
    (97.48 ± 1.47 g/100 g) and total sugar (86.7 ± 2.9 g/100 g) contents were found in palm sugar. The results of this study
    will update and add up to the data for the Malaysian Food Composition Table and can provide useful information in
    choosing healthy foods based on the nutrient contents of the food.
  14. Noradira Suhaime, Masniza Sairi, Nur Biha Mohamed Nafis, Suriati Paiman, Tity Nazleen Mohamed, Zulkifly Abbas, et al.
    Sains Malaysiana, 2018;47:1571-1578.
    The maturity of mango is usually assessed by the determination of its moisture content (m.c.), soluble solid content (SSC)
    and pH. However, these techniques are either time consuming, tedious or destructive. In this research, we extend the
    application of the open-ended coaxial probe technique to determine m.c. and pH of Chok Anan mango from its dielectric
    properties from week 5 to week 17 after anthesis. The effects of frequency and m.c. on the values of the dielectric constant
    and loss factor were also investigated. The critical frequency separating the different polarizations was found to be
    inversely proportional to m.c. Also, in this research we proposed a new classification of fruit ripeness related to the number
    of weeks after anthesis. The actual dielectric properties, m.c., SSC and pH of Chok Anan mango were measured using
    standard methods. Relationships were established between the dielectric constant, loss factor, critical frequency, pH and
    m.c. The accuracy for the determination of m.c. and pH using the coaxial probe was within 1.7% and 3.0%, respectively.
  15. Chuin HC, Che Husna Azhari, Mohamed Aboras, Masfueh Razali, Andanastuti Muchtar
    Sains Malaysiana, 2018;47:1591-1597.
    This study aimed to improve the colloidal stability of yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP)
    suspension through colloidal processing to obtain highly translucent Y-TZP. Agglomeration is often the main complication
    in the processing of nanosized Y-TZP as it deteriorates mechanical and optical properties. Thus, colloidal processing
    is necessary to mitigate the agglomeration in Y-TZP. The colloidal stability of Y-TZP suspension plays a key role for the
    success of colloidal processing. In this study, colloidal processing was conducted at several stages, namely, dispersant
    addition, pH adjustment and sedimentation. Changes in particle size and zeta potential at various stages were recorded.
    The suspensions were then slip-casted to form green bodies. Green bodies were sintered and characterized for density
    and translucency. The results showed that dispersant addition followed by pH adjustment effectively dispersed soft
    agglomerates by introducing electrosteric stabilization, whereas sedimentation successfully segregated hard agglomerates
    and contributed excellent colloidal stability. With high colloidal stability, the translucency of Y-TZP was improved by
    approximately 30%. This study demonstrated different colloidal processing stages and proved that high colloidal stability
    and fine particle size are vital to produce highly translucent Y-TZP.
  16. Nurul Mujahidah Ahmad Khairuddin, Amalina Muhammad Afifi, Katayoon Kalantari, Nur Awanis Hashim, Shaza Eva Mohamad
    Sains Malaysiana, 2018;47:1311-1318.
    Chitosan/polyvinyl alcohol (Chitosan/PVA) blended film was prepared by direct blend process and solution casting methods.
    In order to reduce the swelling ratio and enhance the chemical and mechanical stability, Chitosan/PVA film was crosslinked
    with glutaraldehyde in order to produce Chitosan-g-PVA. Bovine serum albumin (BSA) was used as a model protein
    to incorporate into the Chitosan-g-PVA. The chemical structure and morphological characteristics of films were studied
    by FT-IR and scanning electron microscopy (SEM). Mechanical and physical properties of blended films such as tensile
    properties in the dry and wet states, water uptake and water contact angle measurement were characterized. Blending
    PVA and chitosan improved strength and flexibility of the films. Crosslinking with glutaraldehyde further improves the
    tensile strength and decrease the hydrophilicity of films. BSA immobilized on the Chitosan-g-PVA film was calculated as
    BSA encapsulation efficiency.
  17. Waqas Ahmad, Muhammad Tahir, Riaz Ahmad, Rashid Ahmad
    Sains Malaysiana, 2018;47:1269-1276.
    Zinc (Zn) deficient soil prevails throughout the world and it has become the bottleneck in achieving production potential
    and quality of crops. The negligible use of micronutrients along with irregular use of macronutrients is practised for
    fodder production in Pakistan. Varying levels of zinc (0, 5, 10 and 15 kg ha-1) and nitrogen (0, 60, 120 and 180 kg ha-1)
    were evaluated for their effect on yield, quality and zinc uptake on fodder sorghum (variety Hegari) in a field experiment
    for two consecutive years (2014 and 2015). Data were analysed by using Fishers’ analysis of variance (at p<0.05) and
    response surface methodology (RSM). Correlation between different parameters was also studied. Application of zinc
    and nitrogen improved the plant height, leaf area plant-1, green fodder yield, dry matter yield, crude protein percentage
    and zinc content of plant but decreased the neutral detergent fiber, acid detergent fiber and ash percentage. Values for
    different parameters recorded at second and third levels of zinc and nitrogen were remained at par with each other.
    Application of 10 kg ha-1 zinc and 120 kg ha-1 nitrogen showed an average increase of 7.3 and 18.6% in green fodder
    yield while 12.1 and 15.8% in dry matter yield, respectively. Similarly 6.1 and 7.5% increase in crude protein was noted
    over control. Correlation between NDF and ADF was negative with rest of the studied parameters. In conclusion, Zn2
    and
    N2
    gave the best results in term of yield and quality of fodder sorghum.
  18. Samat S, Yasir M, Yusof M, Rosli M
    Sains Malaysiana, 2018;47:1277-1283.
    Bioaccumulation of toxic metals in fish causes serious threats to human when they are consumed. Thus, the detection of
    toxic element concentration levels in aquatic component is important. The accumulation of some heavy metals such as
    Cd, Cu, Fe, Mn, Pb and Zn in fish were determined. Ten species (Selaroides leptolepis, Decapterus maraudsi, Epinephelus
    lanceolatus, Priacanthus tayenus, Rastrelliger, Megalaspis cordyla, Nibea soldado, Pristipomoides filamentosus, Bramidae
    and Siganus canaliculatus) were collected from Terengganu coastal area, Malaysia. The analysis was done using
    inductive coupled plasma-mass spectrometer (ICP-MS) technique. In general, the concentration levels of heavy metals in
    fish samples are lower than the previous study in various locations. The highest average level of heavy metal recorded in
    fish is Fe followed by Zn, Mn, Cu, Cd and Pb. The metal concentration found in this study was lower than the national
    and international recommended dietary allowance (RDA) for human consumption except Fe (52.33 × 10-2 ± 6.39 × 10-2
    mg kg-1) which exceeded the limit of 0.3 mg kg-1. Long term monitoring system of metal bioaccumulation in fishes need
    to be done to provide useful information for the assessment of the potential health risks of metals in Malaysia.
  19. Muhammad aizat K, Abd shukor R
    Sains Malaysiana, 2018;47:1579-1583.
    Information on semiconductor/superconductor interface is important in fabricating devices of such hybrid systems. In
    this paper the electrical properties and AC susceptibility of Tl2
    Ba2
    CaCu2
    O8
    (Tl-2212) superconductor added with CdTe
    semiconductor are reported. Samples with nominal starting composition Tl2
    Ba2
    CaCu2
    O8
    (CdTe)x with x = 0 to 0.20 weight
    percent (wt. %) have been prepared by the solid-state reaction method. X-ray diffraction patterns showed essentially
    the Tl-2212 phase with presence of impurities (CuO and Tl2
    Ba2
    CuO6
    ) for x ≥ 0.05 wt. % but did not change the Tl-2212
    structure which is tetragonal with lattice parameter a = b ≠ c. The critical onset temperature, Tc-onset for all samples was
    between 104 and 108 K while the critical zero resistance temperature, Tc-zero was from 93 to 95 K. The superconducting
    transition determined by AC susceptibility measurement showed Tcχ’ between 101 and 103 K. The peak temperature, Tp
    of
    the imaginary part of the susceptibility χ” decreased for x = 0.05 and then increased for x > 0.05. This indicated that the
    superconducting grains were strongly coupled for x > 0.05 as a result of CdTe addition. The intergrain critical current
    density, Jc
    at Tp
    for the x = 0.2 sample Jc (Tp
    = 95 K) = 23 A cm-2was the highest among all samples. This sample also
    showed the highest Tp
    indicating CdTe improved the flux pinning of the Tl-2212 phase. This result can be useful in the
    fabrication of semiconductor/superconductor (Tl-2212) hybrid devices.
  20. Syed Nuzul Fadzli Syed Adam, Roslinda Shamsudin, Firuz Zainuddin, Mohd Reusmaazran Yusof
    Sains Malaysiana, 2018;47:1293-1302.
    Kajian ini bertujuan untuk mengkaji kesan kandungan fosfat berbeza (X = 10, 15 dan 20% mol) terhadap pembentukan
    morfologi permukaan, ikatan kimia, penghabluran, fasa dan kekuatan mampatan kaca sol-gel tersinter. Serbuk kaca
    gel dengan komposisi 50SiO2
    .(50-X).CaO.XP2
    O5 (dalam peratusan mol) disediakan melalui kaedah sol-gel, dimampat
    membentuk pelet dan disinter pada suhu 1200°C selama 3 jam. Didapati bahawa dengan peningkatan kandungan fosfat,
    mikrostruktur kaca tersinter yang lebih padat terhasil disebabkan peningkatan pemadatan jasad, pengurangan keliangan
    ketara dan pembentukan butiran dan sempadan butiran berhablur yang lebih besar. Peningkatan sebanyak 20% mol
    kandungan fosfat meningkatkan vitrifikasi (fasa kekaca) pada permukaan kaca tersinter yang mana meningkatkan
    pemadatan jasad kepada 83.56%, kekuatan mampatan pada 113 MPa dan penurunan peratusan penghabluran pada
    sekitar 66%. Analisis EDS menunjukkan peningkatan kandungan fosfat menyebabkan peningkatan unsur Si-O pada fasa
    amorfus dan unsur P-O pada fasa berhablur. Analisis FTIR menunjukkan berlaku pemisahan fasa kaya fosfat dan fasa
    kaya silikat dan pada masa sama meningkatkan rangkaian tetrahedra silikat (Si-O-Si) dan fosfat (P-O-P) kaca tersinter.
    Peningkatan kandungan fosfat meningkatkan kumpulan berfungsi berkaitan fosfat hablur dan mengurangkan kumpulan
    berfungsi berkaitan silikat hablur. Ini menyebabkan peningkatan pembentukan fasa silikokarnotit, Ca5 (PO4)2 (SiO4)
    dalam matriks kaca tersinter dengan peningkatan kandungan fosfat yang ditunjukkan melalui analisis XRD.
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