Displaying publications 181 - 200 of 2561 in total

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  1. Park YG, Choi J, Song I, Park SY, Seol JW, Jackson CJ
    Sains Malaysiana, 2017;46:1895-1902.
    Rheumatoid arthritis (RA) is a chronic disease characterized by inflammation of the joints and their lining or synovium. Previous studies showed that the synovium in RA patients is more hypoxic than normal synovium. Activated protein C (APC) has anticoagulant and anti-inflammatory effects and is highly expressed in the joints of RA patients. We examined the effect of APC on RA and normal synovial fibroblasts under hypoxic conditions. Human synovial fibroblasts were isolated from the synovial tissues of RA patients and normal controls and cells were exposed to recombinant APC under normoxic (21% oxygen) or hypoxic (1% oxygen) conditions. Cell proliferation was measured using MTT assays. Cell lysates and conditioned media were collected and assayed for matrix metalloproteinase (MMP)-2, MMP-9 and p38 using zymography and western blots. Proliferation of both normal and RA synovial fibroblasts dose-dependently increased after APC treatment in normoxic conditions. Under hypoxia, APC enhanced RA cell proliferation but had no effect on normal fibroblasts. MMP-2 production and activation were significantly augmented by APC in both cell types under normoxia and hypoxia conditions. However, activated MMP-2 was more reduced in cells under hypoxia than normoxia. APC substantially reduced the phosphorylation of p38 in normal and RA synovial fibroblasts under hypoxia. No difference in p38 phosphorylation was observed under normoxia. The receptor for APC, endothelial protein C receptor (EPCR), was elevated in normal fibroblasts under hypoxic conditions whereas in RA cells, EPCR was highly expressed under both normoxic and hypoxic conditions. We found that hypoxia enhanced the effect of APC on RA synovial fibroblasts through activation of MMP2 and inhibition of p38 phosphorylation. Our results suggested that APC may suppress joint destruction and progression of inflammation in a hypoxic RA environment.
  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. Amna Shoaib, Arshad Javaid, Nighat Sana
    Sains Malaysiana, 2017;46:1693-1700.
    Collar rot of chili (Capsicum annuum L.) is a very destructive disease caused by a soil-borne fungal pathogen Sclerotium rolfsii Sacc. Generally, chemical fungicides are used to combat the menace but this practice is being discouraged because of health and environmental concerns. In the present study, an alternative environment friendly strategy was used to manage this disease by using farmyard manure (FYM) and two commercial biofertilizers namely Biopower and Feng Shou. S. rolfsii inoculated pot soil was amended with 1% and 2% FYM and the two commercial biofertilizers. Inoculation of soil with S. rolfsii only (positive control) resulted in the highest disease incidence (73%) and plant mortality (60%). Biopower and Feng Shou application reduced disease incidence to 20% and 7%, respectively and plant mortality to 0%. Likewise, 1% and 2% FYM amendment reduced disease incidence to 33% and plant mortality to 26% and 7%, respectively. Under biotic stress of S. rolfsii, FYM and biofertilizers applications, either alone or in combination, significantly enhanced root and shoot growth over positive control. S. rolfsii inoculation significantly increased peroxidase and polyphenol oxidase activities in chili plants which were further increased by application of either of the two biofertilizers. The present study concludes that biofertilizers Biopower and Feng Shou alone or in combination with 2% FYM can be effectively utilized to manage southern blight of chili.
  4. Yuejun He, Changhong Jiang, Hao Yang, Yongjian Wang, Zhangcheng Zhong
    Sains Malaysiana, 2017;46:1701-1708.
    How the composition of the arbuscular mycorrhizal (AM) fungal community affects plant traits of different plant species in karst environments is poorly understood. Broussonetia papyrifera (a woody shrub) and Bidens pilosa (a herbaceous plant) growing in pots in limestone soil were inoculated with an AM fungus, either Funneliformis mosseae (FM), Diversispora versiformis (DV) or Glomus diaphanum (GD) or with an inoculum mixture of all three AM fungi (bn). B. papyrifera and B. pilosa seedlings inoculated with AM fungi showed a significant increase in biomass and nitrogen and phosphorus acquisition compared with the controls, which lacked mycorrhiza. Mixed fungal inoculations significantly enhanced biomass and nitrogen and phosphorus acquisition by B. papyrifera seedlings compared with single fungal inoculations. Nitrogen and phosphorus acquisition by B. papyrifera mycorrhizal seedlings was significantly greater than that of B. pilosa mycorrhizal seedlings. Fungal composition significantly influenced the mycorrhizal benefits of biomass and phosphorus acquisition and mixed fungal inoculations enhanced nitrogen acquisition. Plant species significantly affected nitrogen acquisition but did not have an effect on biomass and phosphorus benefits. We concluded that AM fungal associations increased plant growth and nutrient absorption and that in general a mixed inoculation of AM fungi enhanced biomass and nutrient acquisition more than a single AM fungal inoculation. In addition, a mycorrhizal association was more beneficial for B. papyrifera seedlings in terms of biomass and nutrient acquisition than for B. pilosa seedlings.
  5. Mohanraj K, Sivakumar G
    Sains Malaysiana, 2017;46:1935-1942.
    Nanoparticles of undoped and copper doped with Fe3
    O4 of three concentrations (0.5, 1.0 and 1.5) are synthesized by
    sonochemical method. Structural, optical and morphological properties of these compounds were studied. Fe2+/Fe3+
    ratio is found to be 2.36. Crystalline structure, lattice parameters, surface morphologies, direct and indirect band gap
    energies of the synthesized compounds were estimated and the results are discussed in detail. The XDR analysis indicates
    the Cu doped Fe3
    O4
    nanoparticles have higher crystallinity than undoped samples. Average crystallite size is found
    to increase as Cu concentration increased. The FTIR results are proven by the presence of mixed magnetite-hematite
    nanostructures and it is complement to the XRD results. The presence of spherical, polygonal and agglomeration forms
    of the particles are visually seen in the SEM images. Direct and indirect band gap energy is found to be decreased as the
    copper concentration was increased.
  6. Suhaila Sepeai, Wan Zulhafizhazuan, Cheow SL, Ludin N, Ibrahim M, Sopian K, et al.
    Sains Malaysiana, 2017;46:1943-1949.
    Sel suria adalah peranti semikonduktor yang menukar tenaga matahari kepada tenaga elektrik. Sel suria generasi
    pertama terdiri dari sel suria silikon (Si). Pada masa ini, hampir 90% daripada pasaran pengeluaran fotovolta (PV)
    adalah berdasarkan wafer Si. Ini disebabkan oleh kecekapan dan ketahanan yang tinggi serta jangka hayat yang
    lama iaitu selama 30 tahun. Proses pemfabrikasian piawai bagi sel suria Si dimulakan dengan proses pencucian dan
    penteksturan wafer Si, difusi Fosforus untuk pembentukan pemancar, pembentukan elektrod atas dan bawah melalui
    proses cetakan skrin dan proses pembakaran yang melengkapkan fabrikasi sel suria. Dalam industri, proses piawai
    ini dilakukan pada wafer Si jenis-p. Wafer jenis-n pula mempunyai potensi yang tinggi untuk menghasilkan sel suria Si
    yang berkecekapan tinggi. Namun, proses untuk menghasilkan sel suria silikon atas Si wafer jenis-n melalui proses yang
    lebih rumit dan lama seperti dua peringkat proses difusi menjadikan wafer jenis-p digunakan secara meluas kerana
    dapat merendahkan kos pemfabrikasian. Dalam penyelidikan ini, analisis bagi arus-voltan bagi sel suria Si jenis-n yang
    difabrikasi menggunakan adaptasi proses fabrikasi piawai bagi wafer Si jenis-p akan dibincangkan. Daripada kajian
    simulasi menggunakan perisian PC1D, didapati bahawa kecekapan bagi sel suria jenis-p dan jenis-n yang difabrikasi
    dengan kaedah yang sama adalah 19.63% dan 20.16%. Manakala keputusan eksperimen menunjukkan kecekapan
    sebanyak 9.44% dan 5.51% bagi sel suria jenis-p dan jenis-n.
  7. Jutarut Iewkittayakorn, Juntima Chungsiriporn, Prukraya Pongyeela
    Sains Malaysiana, 2017;46:1763-1769.
    Ammonium-enriched skim latex serum - used for absorption of contaminating ammonia gas - when composted with other rubber tree wastes, is promising as a good compost. The objective of this research was to utilize ammonium-enriched skim latex serum (S) as a raw composting ingredient after being combined with para sawdust (W1) and para rubber leaves (W2). Several ratios of S, W1 and W2 were experimented in a 15L composting vessel to determine the most effective compost. The best ratio was found to be 3:1:3 by weight at 12-day retention. The modified 30 L composting reactor employed with the derived optimum mixing conditions yielded N, P and K of 2.40, 1.51 and 14.84 %w/w. The growth of Brassica alboglabra after application of this compost combined with a chemical fertilizer generated the highest fresh weight (4.48 g/plant). Thus, compost from these wastes could be used as a fertilizer and logically should contribute to cost saving of waste disposal.
  8. Kamangar S, Nik-Ghazali N, Badarudin A, Ameer Ahamad N, Irfan Anjum Badruddin, Govindaraju K, et al.
    Sains Malaysiana, 2017;46:1923-1933.
    The present work was carried out to investigate the blood flow behavior and the severity of blockage caused in the
    arterial passage due to the different geometries such as elliptical, trapezium and triangular shapes of stenosis. The study
    was conducted with respect to various sizes of stenosis in terms of 70%, 80% and 90% area blockage of the arterial
    blood flow. The study was carried out numerically with the help of advance computational fluid dynamic software. It
    was found that the shape of the stenosis plays an important role in overall pressure drop across the blockage region
    of artery. The highest level of pressure drop was observed for trapezoidal shape of stenosis followed by elliptical and
    then by triangular shaped stenosis. The wall shear stress across the stenosis is great for trapezoidal shape followed by
    triangular and elliptical stenosis for same blockage area in the artery.
  9. Nur Suhaili Abd Aziz, Muhammad Khairullah Nor Azmi, Abdul Manaf Hashim
    Sains Malaysiana, 2017;46:1083-1088.
    A one-pot green sonochemical process assisted by ascorbic acid as the reducing agent to produce highly reduced graphene oxide (rGO) decorated with silver nanoparticles (AgNPs) is demonstrated. A complete removal of oxygen-containing group in the GO sheets was confirmed by no observation of the peak corresponds to C-O, C=O and -OH bond. The unexpected decrease of peak intensity corresponds to sp2 hybridized C=C group is explained by a so-called bond polarity effect. The peak observed at ~400 nm seems to show the presence of AgNPs and the red shifting of C=C peak to ~270 nm after the introduction of ascorbic acid indicates the formation of highly reduced GO. The increase of AgNPs size and the crumpled silk-like morphology after the introduction of ascorbic acid also indicate the aggressive reduction of both AgNPs and GO. The increase of ID/IG ratio after the introduction of ascorbic acid seems to indicate the increase of the number of small sp2 domains, the presence of unrepaired defects and the restoration of the sp2 network. This work provides the promising green sonochemical approach by utilizing non-toxic and environmental-friendly reducing agent to produce highly reduced GO decorated with AgNPs for various applications.
  10. Noor Faizah Zainul Abidin, Ibrahim Ahmad, Pin JK, Menon PS
    Sains Malaysiana, 2017;46:1089-1095.
    A planar Graphene Field-Effect Transistor GFET performance with 60 nm gate length was evaluated in discovering new material to meet the relentless demand for higher performance-power saving features. The ATHENA and ATLAS modules of SILVACO TCAD simulation tool was employed to virtually design and assess the electrical performance of GFET. The developed model was benchmarked with the established results obtained from the DESSIS simulator model by using the same graphene channel’s parameters and simulated at fixed threshold voltage of 0.4V. The GFET was also analyzed and ranked its performance for four different gate oxides which includes HfO2, Al2O3, TiO2, and Ta2O5. Compared to the benchmarked device, our GFET shows a competitive performance although it possesses a lower drive current (ION). However, the leakage current (IOFF), subthreshold swing (SS) and the device’s switching capability (ION/IOFF) are more superior than those of the benchmarked device, with an improvement of 99%, 48.3% and 99.36%, respectively. The with different gate dielectrics were also proven to possess a lower IOFF, competitive ION, smaller SS and better switching capability compared to the established DESSISS model. The graphene parameters in this experiment can be utilized for further optimization of GFET with smaller gate lengths.
  11. Ajmal Iqbal, Shahen Shah, Mohammad Nisar, Abdul Ghafoor
    Sains Malaysiana, 2017;46:1727-1734.
    Twenty lines of Pisum sativum particularly developed for high yield and resistant to powdery mildew were evaluated along with two parents (Falloner and 11760-3ER) and two checks (Climex and a local cultivar) with the objectives to determine morphological characterization, yield potential and resistance to powdery mildew. On the basis of one way cluster, the 24 lines were mainly grouped into four clusters, especially on the vegetative and yield contributing traits. It was observed that the tall and high yielding lines were grouped in cluster-III while the dwarf and high yielding lines were grouped in cluster-IV. Analysis of variance (ANOVA) showed significant difference (p<0.05) in the yield of 24 pea lines. The average grain yield of the 24 pea lines ranged from 22.87 to 102.54 g. The highest grain yield was produced by PL-4 (102.54 g plant-1) followed by PL-5 (82.14 g plant-1). Of the 24 pea lines, two lines (PL-4 and PL-5) were highly resistant to powdery mildew disease. Therefore, the newly developed PL-4 and PL-5 lines were high yielding and highly resistant. Among the 19 morphological traits, six (Eigenvalue >1.0) contributed more than 80% variability among the materials.
  12. Farahani Mohd Saimi, Othman Jaafar, Firdaus Mohamad Hamzah
    Sains Malaysiana, 2017;46:1735-1741.
    Presently, climate change plays an important role as it gives a serious impact to the living things on earth. Analyzing the trend of climate change is very important in identifying the pattern of changes because it can give an initial overview for future analysis. In this study, trend analysis was carried out to study the pattern of changes for five climate change parameters, such as total amount of monthly precipitation (mm), monthly average temperature (°C), monthly average global radiation (MJm–2), monthly average wind speed (m/s) and monthly average humidity (%) during the period of 1974 to 2010. Comparisons were made between two research stations, which were the Senai International Airport and Kluang Meteorological Stations. In this study, the Mann-Kendall trend test and Sen’s slope estimator test were used to identify the monotonic trend for these climate change parameters. As a result of this analysis, the precipitations showed no trend for both locations and the radiation showed no trend in Kluang from both analyses. Meanwhile, other parameters in Senai and Kluang showed a monotonic trend, according to the Tau value (Z) and the Sen’s slope value. The temperature shows a positive trend for both locations.
  13. Nishata Royan Rajendran Royan, Abu Bakar Sulong, Nor Yuliana Yuhana, Mohd Hafizuddin Ab Ghani, Sahrim Ahmad
    Sains Malaysiana, 2017;46:1749-1756.
    Kaedah tindak balas permukaan (RSM) telah digunakan untuk mengoptimumkan penyediaan biokomposit rHDPE berpenguat sekam padi sebagai pengisi. Sekam padi adalah sisa pertanian yang mempunyai ciri-ciri kayu dan digunakan secara pesat dalam bidang komposit kayu plastik. Kesan parameter suhu, tekanan serta masa proses tekanan panas ke atas kekuatan tegangan telah dikaji. Reka bentuk Box Bechken telah digunakan untuk menentukan parameter optimum biokomposit yang mempunyai kekuatan tegangan yang tinggi. Model tertib kedua telah dibangunkan untuk meramalkan kekuatan tegangan berdasarkan reka bentuk komposit. Didapati bahawa komposit sesuai digunakan apabila model regresi kuadratik dengan pekali penentu bilang (R2) yang tinggi. Keadaan proses menekan yang optimum dicapai pada suhu 180°C, tekanan 1000 psi dan masa 9 min dengan pekali penentu berbilang mencapai 97%. Di bawah keadaan yang optimum ini, komposit yang mengandungi 10, 20, 30, 40 dan 50% gentian RH telah disediakan. Kekuatan tegangan dan modulus tegangan biokomposit menunjukkan peningkatan apabila kandungan gentian RH ditambah.
  14. Nacide Kizilda?, Hüsniye Aka Sa?liker, Cengiz Darici
    Sains Malaysiana, 2017;46:1757-1762.
    The environmental risk of Chromium (Cr) pollution is pronounced in soils adjacent to chromate industry. It is important to investigate the functioning of soil microorganisms in ecosystems exposed to long-term contamination by Cr. The aim of this study was to determine the effects of Cr on carbon mineralization in soil. The study was carried out in soils contaminated and uncontaminated with Cr near and away from a Cr mine in three different districts (Bozluk, Kızılyüksek and Yanıkçam) of East Mediterranean Region, Turkey. Carbon mineralization were determined in soils humidified 80% of field capacity at 28°C over 30 days under the same laboratory conditions. These results showed that carbon mineralization was greatly inhibited by the presence of Cr in all contaminated sites. Based on these results, microbial activity can use as an indicator for the Cr pollution level in the soil ecosystems.
  15. Hanani Abdul Manan, Zamzuri Idris, Jafri Malin Abdullah, Mohammed Faruque Reza, Wan Nor Azlen Wan Mohamad
    Sains Malaysiana, 2017;46:1877-1886.
    Visual function is mainly located within the bilateral hemisphere of the occipital lobes of the brain. However, our functional magnetoencephalography (MEG) result has demonstrated the reorganization of brain activity in the occipital area in patients with left-sided brain tumour. The results showed that brain laterality changes from bilateral to unilateral activation of the occipital area. Right occipital area (contralateral areas to the tumour), shows increase intensity of activation. Diffusion tensor imaging (DTI) with fibre tracking was performed to further investigate this brain laterality modification and the findings confirmed there is an alteration in the left hemisphere fibre optic tracts. This functional modification and changes of the brain laterality and optic tracts in the brain is suspected to be the result of tumour growth induced changes. The present observation will be discussed in term of the mechanism of tumour induced reorganization and changes with the corroborating evidence from MEG, DTI and neuropsychological assessment.
  16. TianXin Lai, Eric Tzyy Jiann Chong, Ping-Chin Lee, Jitt Aun Chuah, Kek Heng Chua
    Sains Malaysiana, 2018;47:141-148.
    STK15 is a serine/threonine kinase that regulates chromosomal segregation during mitosis. Single nucleotide polymorphisms (SNPs) in this gene, Phe31Ile (rs2273535) and Val57Ile (rs1047972), are inconsistently associated with gastrointestinal cancer (GIC) across different populations. However, this association is unclear in Malaysian population. Therefore, this study investigated the association of STK15 Phe31Ile and Val57Ile polymorphisms to GIC risk in Malaysia. Genomic DNA was extracted from 185 GIC patients and 1110 healthy controls and was subjected to polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. SNPs were further confirmed using sequencing. We found that the 31Phe allele and 31Phe/Phe genotype in the Phe31Ile SNP significantly increased GIC risk in Malaysian population, particularly in gastric cancer (p<0.017). The combined analysis for both SNPs also increased the risk of GIC in this study. Etiological factors such as age, gender and ethnicity were not associated with GIC in the population. This is the first study to report the association of STK15 Phe31Ile and Val57Ile SNPs with an increased risk of GIC in Malaysians; the 31Phe allele is exclusively associated with the risk of gastric cancer. In addition, GIC incidences among Malaysians have significantly shifted to a younger age (<50 years).
  17. Abdul Halim Abdul Gafor, Rozita Mohd, Rizna Cader, Kong Wei Yen, Marlyn Mohamad, Shamsul Azhar Shah, et al.
    Sains Malaysiana, 2018;47:149-155.
    Cardiovascular disease (CVD) is a major cause of morbidity and mortality in chronic kidney disease (CKD) patients. This study aimed to determine the roles of CVD biomarkers in CKD patients. This was a case-control study which recruited consecutive patients with stage 2-4 CKD patients with and without CVD. Serum levels of highly-sensitive C reactive protein (hs-CRP), cystatin C (CysC), asymmetrical dimetylarginine (ADMA) and symmetrical dimethylarginine (SDMA) were measured. Sixty two stage 2-4 CKD patients with a mean age of 60.3 ± 10.4 years were recruited. Twenty three (37.1%) of them had CVD. Those CKD patients with CVD were older (64.1±8.0 vs 58.1± 1.1, p<0.05) and had significantly higher systolic blood pressure (139.4 ± 16.2 vs 129.4 ± 14.8 mmHg, p<0.05). Diabetic patients had 8 times (95% CI 1.25-51.77, p< 0.05) higher risk to develop CVD. CKD patients with CVD had a higher serum creatinine (185.0 ± 54.1 vs 154.1 ± 54.4 μmol/L, p<0.05), a lower estimated glomerular filtration rate (33.7 ± 12.2 vs 42.2 ± 14.5 mL/min/1.73m2 p<0.05) and a lower triglyceride levels (1.3 (1.1-1.7) vs 1.8 (1.4-2.3) mmol/L, p<0.05), compared to those without CVD. Fasting blood sugar was 7.1 ± 2.7 mmol/L in CVD group and 6.3 ± 1.6 mmol/L in non CVD group (p>0.05). There were no differences in their mean serum levels of hs-CRP, CysC, ADMA and SDMA. Risk factors including age, diabetes mellitus, hypertension and renal functions were still the most important CVD risk factors in CKD patients.
  18. Ahmad Shuhaimi Abu Bakar, Hasan Abbas Jaffery, Mohd. Faizul Mohd. Sabri, Syed Waqar Hasan, Suhana Mohd Said
    Sains Malaysiana, 2018;47:403-408.
    Thermally driven electrochemical cells (thermocells) are able to convert thermal gradient applied across redox electrolyte
    into electricity. The performance of the thermocells heavily depends on the magnitude and integrity of the applied thermal
    gradient. Herein, we study the iodide/triiodide (I–/I3
    –) based 1-Ethyl-3-methyl-imidazolium Ethylsulfate ([EMIM][EtSO4])
    solutions in a thermocell. In order to comprehend the role of fluidity of the electrolyte, we prepared set of solutions by
    diluting [EMIM][EtSO4] with 0.002, 0.004, and 0.010 mol of Acetonitrile (ACN). We realized a significant improvement
    in ionic conductivity (σ) and electrochemical Seebeck (Se) of diluted electrolytes as compared to base [EMIM][EtSO4]
    owing to the solvent organization. However, the infra-red thermography indicated faster heat flow in ACN-diluted-[EMIM]
    [EtSO4] as compared to the base [EMIM][EtSO4]. Therefore, the maximum power density of base [EMIM][EtSO4] (i.e.
    118.5 µW.m-2) is 3 times higher than the ACN-diluted-[EMIM][EtSO4] (i.e. 36.1 µW.m-2) because of the lower thermal
    conductivity. Hence this paper illustrates the compromise between the fast mass/flow transfer due to fluidity (of diluted
    samples) and the low thermal conductivity (of the pure [EMIM][EtSO4]).
  19. Jadeera Phaik Geok Cheong, Sareena Hanim Hamzah, Mohamad Shariff A. Hamid, Nur Syamsina Ahmad
    Sains Malaysiana, 2018;47:123-129.
    Menstrual irregularity and disordered eating were previously identified as risk factors for low bone mineral density
    (BMD) in female athletes. Therefore, an investigation for more potential factors that could be associated with low BMD
    among Malaysian female athletes is required. The aim of this study was to assess the association of BMD with energy
    availability, body weight, body fat, estrogen level and bone loading status in female athletes and to what extent those
    factors predict BMD. Energy intake and expenditure, body weight, Bone Physical Activity Questionnaire (BPAQ) score
    and estrogen level were determined from 85 female athletes aged 18-30 years in this cross-sectional study. Bone mineral
    density was measured by using an ultrasound bone densitometry device at the calcaneus bone. The female athletes’ body
    weight and fat percentage were 56±9 kg and 27±6%, respectively and they were all eumenorrheic. Fifty three percent
    of them had low BMD (z- score < 0). Their mean energy intake (1291±33 kcal/day) was lower than energy expenditure
    (1807±34 kcal/day) which resulted in a low energy availability (29±1 kcal/day/kg FFM). BMD was positively associated
    with BPAQ score (r=0.4, p=0.000) and body weight (r=0.3, p=0.005) but negatively associated with energy expenditure
    (r=-0.4, p=0.000). There was no association of BMD with energy intake, energy availability, body fat percentage and
    estrogen level. In conclusion, BMD was associated with energy expenditure, body weight and BPAQ score among female
    athletes. Regression analysis showed that energy expenditure and BPAQ score were the main factors to predict BMD.
  20. Siti Mariam Norrulashikin, Fadhilah Yusof, Ibrahim Lawal Kane
    Sains Malaysiana, 2018;47:409-417.
    The vector autoregressive (VAR) approach is useful in many situations involving model development for multivariables
    time series. VAR model was utilised in this study and applied in modelling and forecasting four meteorological variables.
    The variables are n rainfall data, humidity, wind speed and temperature. However, the model failed to address the
    heteroscedasticity problem found in the variables, as such, multivariate GARCH, namely, dynamic conditional correlation
    (DCC) was incorporated in the VAR model to confiscate the problem of heteroscedasticity. The results showed that the use
    of the VAR coupled with the recognition of time-varying variances DCC produced good forecasts over long forecasting
    horizons as compared with VAR model alone.
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