Displaying publications 81 - 100 of 2561 in total

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  1. Mardan M, Hakeem K, Faridah-Hanum I, Saari N
    Sains Malaysiana, 2013;42:1409-1424.
    The present study was carried out to investigate the composition of species and species diversity at Compartment 28A in the Ulu Muda Forest Reserve (UMFR), located in north-west of Peninsular Malaysia. The area covered was one ha. Stems with diameter at breast height (dbh)as ≥ 1 cm were enumerated, identified and their height measured. The importance value index (IVI) was estimated to show which species have the highest value, since species density was also estimated. We recorded 722 species from 81 genera belonging to 42 families. The highest IVI was recorded for Macaranga hosei (42.40). It was also the highest in stand density (33 individuals / 4.43 %) in one ha. Species from Euphorbiaceae were represented at the highest level, with 11 genera (about 210 individuals). The total above-ground biomass (TAGB) in one ha using three different modifications from Kato et al. (190.3 t/ha), Kueh and Lim (2522.8 t/ha) and Lim (174.7 t/ha) were noted from family Dipterocarpaceae.
  2. Inthanuchit KS, Udomuksorn W, Kumarnsit E, Vongvatcharanon S, Vongvatcharanon U
    Sains Malaysiana, 2017;46:1903-1911.
    Pueraria mirifica (PM) is a phytoestrogen-rich plant that was tested to establish if its phytosteroids could prevent estrogen dependent sarcopenia. The effect of PM on the estrogen levels, estrous cycle, toxicity, muscle mass, strength and endurance of extensor digitorum longus (EDL) and gastrocnemius muscles of ovariectomized rats was investigated. Adult female Wistar rats were divided into six groups: Sham-operated (SHAM); ovariectomized (OVX) fed with distilled water (PM0); OVX injected with 40 μg/kg estradiol benzoate (E40); (4-6) OVX fed with ethanolic extract of PM at doses of 50 (PM50), 500 (PM500) and 1000 (PM1000) mg/kg for 90 days. After treatment with all three doses of PM, no toxicity was detected to the hematopoietic system and liver function whereas the E40 group did show toxic effects. Treatment with 50 and 500 mg/kg of PM showed no effect on uterine hypertrophy and caused no arrest of the estrous cycle whereas treatment with estrogen and 1000 mg/kg of PM treatment did. The estrogen level, the cross sectional area of the EDL and the gastrocnemius muscle fiber strength and endurance were all significantly reduced in the PM0 group compared to that of the SHAM group (p<0.05) but were significantly increased in the E40, PM50, PM500 and PM1000 compared to that of the PM0 group (p<0.05). This indicated that the estrogenic activity of PM alleviated muscle atrophy and built up muscle strength and endurance. Thus, the 50 and 500 mg/kg of PM were suitable for treating estrogen dependent sarcopenia in ovariectomized rats.
  3. Velichkova KN, Sirakov IN, Beev GG, Denev SA, Pavlov DH
    Sains Malaysiana, 2016;45:601-608.
    The aim of present study was to explore the effect of different carbon sources on biomass accumulation in microalgae Nannochloropsis oculata and Tetraselmis chuii and their ability to remove N and P compounds during their cultivation in aquaculture wastewater. Microalgae cultivation was performed in laboratory bioreactor consisted from 500 mL Erlenmeyer flasks, containing 250 mL wastewater from semi closed recirculation aquaculture system. The cultures were maintained at room temperature (25-27ºC) on a fluorescent light with a light: dark photoperiod of 15 h: 9 h. The microalgae species were cultivated in wastewater with different carbon sources: glucose, lactose and saccharose. The growth of strains was checked for 96 h period. In the present study, N. oculata and T. chuii showed better growth in wastewater from aquaculture with saccharose carbon source during the experiment. The most effective reduce of nitrate and total nitrogen was proved in N. oculata cultivated in wastewater with glucose as carbon source. T. chuii cultivated in wastewater containing glucose showed 8.27% better cleaning effect in ammonium compared with N. oculata. T. chuii grew in wastewater with glucose as carbon source showed 19.5% better removal effect in phosphate compared with N. oculata strain.
  4. Yazariah M. Yatim, Brian R. Duffy, Stephen K. Wilson
    Sains Malaysiana, 2013;42:975-980.
    We investigate unsteady flow of a thin film of Newtonian fluid around a symmetric slender dry patch moving with constant velocity on an inclined planar substrate, the flow being driven by a prescribed constant shear stress at the free surface of the film (which would be of uniform thickness in the absence of the dry patch). We obtain a novel unsteady travelling-wave similarity solution which predicts that the dry patch has a parabolic shape and that the film thickness increases monotonically away from the dry patch.
  5. Mohammad Sarwan Mohd Sanif, Amgad Ahmed Ali, Lee MW, Lee HW, Chia Sheng DB, Abdul Manaf Hashim
    Sains Malaysiana, 2017;46:1119-1924.
    The effects of the annealing temperatures and thicknesses on the shapes, sizes and arrangement of platinum (Pt) nanoparticles (NPs) on graphene and their sensing performance for hydrogen (H2) detection were investigated. It shows strong dependency of the annealing temperatures and thicknesses on the properties of NPs. It was found that the proposed technique is able to form the NPs with good size controllability and uniformity even for thick deposited layer, thus eliminating the requirement of very thin layer of below 5 nm for the direct NP synthesis by evaporation or sputtering. The transport properties of Pt NPs/graphene structure and its sensing performance on H2 at room temperature under various H2 concentration were evaluated. The results showed an acceptable sensing response, indicating an innovative approach to fabricate Pt NPs embedded graphene for gas sensing application.
  6. Lum CY, Ong LH, ÄŒepic M
    Sains Malaysiana, 2011;40:1123-1127.
    The transition of orthogonal smectic A (SmA) phase to the tilted phases, upon lowering the temperature, is explored with a discrete phenomenological model and the phase diagrams are presented. The results show that the transition of SmA to uniplanar structures can be affected by the effect of chirality. The areas showing the uniplanar phase in the phase diagrams diminish with the increase in effect of chirality.
  7. Rofina Yasmin Othman, Jennifer Ann Harikrishna, Gan KS, Tan CS
    Sains Malaysiana, 2018;47:499-509.
    The Nipah virus is highly virulent to swine and humans. The envelope attachment glycoprotein (G) of Nipah virus
    plays a key role in viral entry and induction of neutralizing antibody in mammalian hosts, thus is considered a good
    candidate for vaccine development. Plant transient expression systems are gaining recognition as a viable alternative
    for the production of vaccine antigens. In this study, we expressed the Nipah virus G protein heterologously in Nicotiana
    benthamiana using an agroinfiltration approach. The highest expression of recombinant G protein in N. benthamiana at
    RNA and protein levels was detected on day 9 post-infiltration. Western blot analysis demonstrated that the purified G
    protein reacted specifically with rabbit anti-Nipah Virus serum, indicating its potential for vaccine use.
  8. Siti Nurhadis Che Omar, Kien-Hui Chua, Bee See Goh, Muhammad Azhan Ubaidah, Lokman Saim, Khairul Anuar Khairoji, et al.
    Sains Malaysiana, 2018;47:2349-2358.
    The limitation of self-repair and proliferation capacity of chondrocytes in cartilage reconstruction lead to alternative
    search of cell source that can improve the auricular regeneration. Human adipose-derived stem cells (HADSC) are an
    alternative cell source that have unique characteristics to self-renew and differentiate into various tissues making it
    suitable for cell therapy and tissue engineering. This study aimed to examine the chondrogenic differentiation potential of
    (HADSC) in monolayer culture by the presence of different transforming growth factor beta’s, TFG-β1, -β2 and -β3. HADSC
    at passage 3 (1.5 × 105 cell/mL) were cultured in chondrogenic medium containing 5 ng/mL of different transforming
    growth factor beta’s, TFG-β1, -β2 and -β3 for 7, 14 and 21 days. Data analysis was evaluated based on the growth
    rate of cells, cells morphological changed, production of collagen type II and glycosaminoglycan sulphate (sGAG). The
    quantitative RT-PCR was carried out to determine the chondrogenic, fibrogenic and hypertrophic gene expression levels.
    Differentiation of HADSC into chondrocytes using TFG-β indicates the occurrence of the chondrogenesis process. The best
    chondrogenic differentiation was observed in HADSC induced by TFG-β3 through the chondrocytes-like cells morphology
    with cells aggregation and high production of proteoglycan matrices compared to other TGF-βs groups. Additionally,
    the expression of chondrocytes-specific genes such as Type II collagen, Aggrecan core protein, Elastin and Sox 9 was
    high. In conclusion, this study has showed that TGF-β3 is the potential growth factor in producing chondrogenic cells
    for auricular cartilage tissue engineering.
  9. elvira pederes de lara-tuprio, Varayu boonpogkrong
    Sains Malaysiana, 2017;46:2549-2554.
    n this paper, transformation and differentiation of Henstock-Wiener integrals are discussed. The approach is by Riemann sums. The idea is more transparent than that of classical Wiener integral.
  10. Nik Marzuki Sidik, Roslina Mat Yazid, Che Radziah Che Mohd. Zain, Ismanizan Ismail
    Metalotionin (MT ) merupakan protein pengikat logam berberat molekul rendah dan kaya dengan sistein yang hadir dalam pelbagai jenis organisma termasuklah bakteria, kulat, tumbuhan dan haiwan. MT tumbuhan dipercayai mengambil bahagian dalam metabolisme dan penyahtoksikan logam dengan cara pengkelatan ion-ion logam berat. Fungsinya yang unik ini telah mendorong minat untuk memencilkan gen MT daripada rumput sambau, Eleusine indica. DNA pelengkap (cDNA) eiMT 1 telah diklonkan ke dalam vektor binari pBI121 untuk ditransformasikan ke dalam pokok tembakau melalui perantaraan Agrobacterium tumefaciens. Penyaringan pokok tembakau transgenik dengan PCR dilakukan menggunakan 3 pasang pencetus yang direka khas iaitu pasangan CMT F dan CMT R, 35SF dan PMT R, dan pasangan pencetus khusus-gen MT FS2 dan MT RS2. Ketiga-tiga pasangan pencetus ini berjaya menghasilkan saiz serpihan DNA jangkaan iaitu masing-masing 270 pb, 1.1 kb dan 170 pb. Penjujukan terhadap serpihan bersaiz 170 pb dan analisis jujukan menunjukkan persamaan 100 % dengan eiMT 1. Kajian pengekspresan gen melalui pendekatan transkripsi berbalik-PCR membuktikan bahawa transgen eiMT 1 telah berjaya diekspreskan dalam 11 daripada 19 pokok transgenik yang dikaji.
  11. Nurul Izzah Ab Rahman, Musa Ahmad
    Sains Malaysiana, 2006;35:7-10.
    Kajian pemegunan enzim peroksidase dalam membran hibrid sol-gel-kitosan untuk penyediaan transduser optik hidrogen peroksida telah dilakukan dalam pembinaan biosensor. Kajian ini merangkumi pengoptimuman nisbah sol-gel-kitosan, pencirian enzim dalam larutan bebas dan pemegunan enzim dalam hibrid sol-gel-kitosan serta penciriannya. Spektrum serapan bagi setiap pencirian ditentukan menggunakan Spektrofotometer uL-Nampak. Hasil kajian menunjukkan aktiviti enzim tidak berubah selepas pemegunan. Nisbah optimum hibrid sol-gel-kitosan adalah 4:6. Nilai sisihan piawai relatif (RSD) untuk kebolehulangan kaedah ini adalah 2.71% dan 3.76%, masing-masingnya untuk enzim bebas dan enzim terpegun.
  12. Miskon FM, Noor Azhar Mord Shazili, Faridah Mohammad, Kamaruzzaman Yunus
    Sains Malaysiana, 2014;43:529-534.
    The selected trace metals in the soft tissue of Thais clavigera from 11 sampling sites along the coastal waters of the east coast of Peninsular Malaysia were studied. Significant inter-spatial variations in trace metals were recorded. Sites with relatively high concentrations of the contaminant metals Hg, Cd, Pb and Zn are correlated to their close proximity to industrial and urban sites or to boating and aquaculture activities. This could possibly be contributed by the high growth of industrial activities like port and sewage release. Interspatial comparison with previous studies indicated lower measurement. Meanwhile, comparison with other studies around the world also designated lower values except for Zn. The metal accumulation patterns indicated an enrichment of essential metals over non-essential metals. Comparison of metal concentration with maximum permissible limits of toxic metals in food established in different countries, as well as Malaysian Food Act 1983 and Food Regulations 1985 Fourteen Schedule, indicated the values were well within safety levels.
  13. Chua HP, Aminah Abdullah, Murugaiyah M
    Kacangma (Leonurus sibiricus L.) is a popular traditional herb that has been consumed for decades by the people of Sarawak as a herbal medicine or culinary ingredient. The toxicity of dried kacangma herb on Sprague Dawley male and female rats was evaluated through 90-day sub-chronic studies. The rats were fed kacangma at the rate of 0.5 (low dose), 5 (medium dose) and 25 (high dose) g/kg body weight. The control groups of rats received only the commercial rat pellet. Minor treatment-related effects were observed for body weights, organ weights and the lipid profile parameters and these did not appear to be of toxicological significance. In the sub-chronic toxicity studies, some indications of renal and liver toxicity were evident in the medium and high dose groups when plasma creatinine and liver enzymes were found to be higher when compared with the control and the low dose groups. The hematology study reveals statistically significant mild anemia in rats from the medium and high dose groups as indicated by decreases in hemoglobin, red blood cell count and packed cell volume (hematocrit value). Administration of kacangma herb at medium and high dose was also found to cause adverse effects in histopathological structure of the liver and kidney of both male and female rats. However, low dose group showed no significant differences compared to the control. Therefore, it is considered safe and less chance of developing toxicity if the herb is consumed at the dose of 0.5 g/kg body weight as observed throughout the 90 days period of sub-chronic study.
  14. Muhammad Taher, Nur Aizura Mat Alewi, Deny S, Zaitunnatakhin Zamli, Norazsida Ramli, Nurulwahida Saad
    Sains Malaysiana, 2012;41:1423-1429.
    Sapium baccatum is usually used as a timber in Malaysia. Its medicinal values are not well known and very little research has been conducted concerning the plant. Consequently, this study was conducted to observe toxicity effects of hexane extract of stem bark of S. baccatum. The toxicity effects were assessed through observation of physiological changes of the rats as well as through gross and histological examinations of its livers. The doses for the treated groups were given intraperitoneally for T2, T3 and T4 group which were given 100, 250 and 500 mg/kg, respectively. Meanwhile, control group (T1) was administered with 80% PEG 200 only. The observation period was 14 days. If the rat died, it was dissected and the liver was removed and examined. Some physiological effects observed include ataxia and hind-legs paralysis. The gross observations of the livers, growth of abnormal spots and connective tissues attachment to lobes of the livers were observed. The experiment was followed byhistopathological observation, which indicated the presence of abnormal hepatocytes with a distorted shape and undefined cell linings for T2 group. Results also indicated an increase in the distortion of hepatocytes, presence of massive cytoplasm and necrosis of hepatocytes for T3 and T4 groups. The results suggest that non polar extract of the stem bark of S. baccatum may promote toxic effects to the animals.
  15. Wan Rosli WI, Nurhanan A, Mohsin S
    Sains Malaysiana, 2012;41:1217-1221.
    Total polyphenol content and free radical scavenging activity of cornsilk (Zea mays hairs) extracts were determined. Our result showed the total polyphenol content of methanolic and water extracts were 272.81 mgGAE/100 g and 256.36 mgGAE/100 mg dry plant, respectively. The total flavanoid content of methanolic extract (38.01 mg catechin equivalent/100 g) was significantly higher (p<0.05) than the water extract (4.11 mg catechin equivalent/100 g). In radical scavenging activity, the activity of methanolic extract was significantly higher (p<0.05) than the water extract. The methanolic extract scavenged at 81.7% of free radicals at 1000 μg/mL while the water extract showed 63.5% of inhibition. In conclusion, cornsilk contained high polyphenol components with strong free radical scavenging activity thus could be considered as potential source of natural antioxidant.
  16. Kong K, Khoo H, Amin I, Prasad N, Chew L
    Sains Malaysiana, 2013;42:123-137.
    This study aimed to evaluate the total phenolics and antioxidant capacities of the seeds, pulp and peel of Pouteria campechiana fruit using three extraction solvents (water, 70% methanol and 70% ethanol). Among them, 70% ethanol exhibited the best solvent for yielding highest total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities. The result showed that 70% ethanol extract from the peel contained the highest TPC (2304.7 mg gallic acid equivalent/100 g dw) while the pulp has the highest TFC (6414.03 mg rutin equivalent/100 g dw). The antioxidant activities of the pulp and peel ethanolic extracts were high as determined using 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation assay (49.60 and 49.56 mmoL TE/100 g dw) and ferric reducing antioxidant power assay (43.88 and 42.94 Fe2+/100 g dw) but not for seeds. However, their diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities were ~88%. Thus, the pulp and peel of P. campechiana fruit can be utilized as natural source for antioxidant components.
  17. Mohd Razif Mohd Idris, Fazlina Nordin, Fadilah Abd Wahid S, Zaleha Abdullah Mahdy
    Sains Malaysiana, 2018;47:2491-2499.
    The aim of this study to determine the numbers of CD34+ cells and total nucleated cell (TNC) in umbilical cord blood (UCB)
    collected from pregnant mothers with gestational diabetes mellitus (GDM) and preeclampsia (PE), following statistical
    analysis of both maternal and perinatal factors which affect UCB parameters. Most of studies explored the influence of
    obstetric factors on the number of UCB cell collection and only a few looked at the effects on UCB haematopoietic stem
    cell (UCB-HSC) of common disorders complicating pregnancy. A total of 112 UCB samples (32 PE, 42 GDM and 38 nondiseased) were collected. CD34+ cell and NC count were enumerated using FACS Calibur. The TNC and CD34+ cells were
    significantly reduced in both PE and GDM groups as compared to the control group. The PE group shows significantly
    lower birth weight and higher BP which led to a lower UCB volume and CD34+ count. Gestational age shows significant
    correlation with nucleated cell count (NCC) and TNC. GDM group shows significantly lower systolic BP, NCC and TNC count,
    including low placental weight and birth weight. Conclusively, some obstetrics factors have significant influences to the
    numbers and quality of UCB-HSC in both PE and GDM groups, which could guide in the selection criteria for CB banking.
  18. Othman A, Gopir G
    Sains Malaysiana, 2013;42:955-959.
    The topology of the electron density yields a faithful and a reliable mapping of the concepts of atoms, molecular structure, bonds and structure, besides providing the basis for a theory of structural stability. In quantum mechanics and in particular quantum chemistry, the electron density is a measure of the probability of an electron occupying an infinitesimal element of space surrounding any given point. Contour plots of electron density distribution of cadmiun telluride (CdTe) were obtained using the density functional theory (DFT) method and were used as the basis to qualitatively study the bond, structure and stability of the molecule when it is in bulk. We looked at the way the electron density, ρ of CdTe defines the gradient field and hence the bonding type. We identified the bond paths that coincide with the contours of electron sharing. These bond paths indicated that the molecule was slightly covalent. Our topological analysis led us to conclude that CdTe was an n-type semiconductor with covalent bond and slight ionic character.
  19. KASIM M, CHE HARON C, GHANI J, GUSRI A, YAZID M, SULAIMAN M
    Sains Malaysiana, 2013;42:1721-1726.
    This paper presents the tool life of the end milled Inconel 718, which is part of a material that is difficult to be machined. Previous researchers found that tool life in machining aged Inconel 718 is shorter compared with other materials. However, this observation required further investigation. Thus, a raw grade Inconel was proposed in this experiment. The experiments were performed using TiAlN-coated carbide. The studied milling parameters were the cutting speed, Vc, from 90 to 150 m/min; feed rate, fz, from 0.15 to 0.25 mm/rev; depth of cut, ap, from 0.3 to 0.5 mm; and radial depth of cut, ae=1 mm. The application of the cutting fluid used in this experiment was a minimum quantity lubricant, which had the advantage of cooling effectiveness and low consumption of cutting fluid. The results showed that the feed rate, fz, was the primary factor controlling the tool life. The combination of Vc=115 m/min, fz=0.15 mm/tooth, as well as ap=0.5 mm and ae=0.15 mm gave the longest tool life that served 95.38 min in operation.
  20. Damanhuri H, Abdul Rahim N, Nasri W, Tan J, Makpol S, Wan Ngah W
    Sains Malaysiana, 2016;45:1363-1370.
    Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by deterioration of the brain functions
    that result in impairment of memory, cognition and behavioural functions. Oxidative stress is well known to be one of the
    causative factors for AD. Thus this disease is potentially modulated by natural antioxidants such as vitamin E. The aim
    of this study was to evaluate the effect of tocotrienol-rich fraction (TRF) supplementation on antioxidant enzymes and
    DNA damage using APPswe/PS1dE9 transgenic mouse model of AD. Animals were supplemented with TRF (200 mg/kg)
    or alpha-tocopherol (αT) (200 mg/kg) for six months starting from nine months old. We found that superoxide dismutase
    (SOD) activity in AD mouse was decreased by supplementation of TRF and αT as compared with AD control mouse with no
    significant differences in glutathione peroxidise (GPx) activity in all groups. TRF supplementation significantly increased
    catalase (CAT) activity. The level of DNA damage of AD mouse shows significant decrease with supplementation of TRF
    and αT. In conclusion, TRF was able to modulate antioxidant enzymes activity and decreased the level of DNA damage
    of AD transgenic mouse model.
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