Displaying publications 41 - 60 of 144 in total

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  1. Fulltext Symmetric resonator based tunable epsilon negative near zero index metamaterial with high effective medium ratio for multiband wireless applications
    Moniruzzaman M, Islam MT, Hossain I, Soliman MS, Samsuzzaman M, Almalki SHA
    Sci Rep, 2021 Nov 08;11(1):21842.
    PMID: 34750440 DOI: 10.1038/s41598-021-01266-7
    In this paper, a tuned metamaterial (MTM) consisting of a symmetric split ring resonator is presented that exhibits epsilon negative (ENG), near zero permeability and refractive index properties for multiband microwave applications. The proposed metamaterial is constituted on a Rogers (RT-5880) substrate with 1.57 mm thickness and the electrical dimension of 0.14λ × 0.14λ, where wavelength, λ is calculated at 4.2 GHz. The symmetric resonating patch is subdivided into four equal and similar quartiles with two interconnecting split rings in each quartile. The quartiles are connected at the center of the substrate with a square metal strip with which four tuning metal strips are attached. These tuning metal strips are acted as spacers between four quartiles of the resonator patch. Numerical simulation of the proposed design is executed in CST microwave studio. The proposed MTM provides four resonances of transmission coefficient (S21) at 4.20 GHz, 10.14 GHz, 13.15 GHz, and 17.1 GHz covering C, X and Ku bands with negative permittivity, near zero permeability and refractive index. The calculated effective medium ratio (EMR) is 7.14 at 4.2 GHz indicates its compactness. The resonance frequencies are selective in nature which can be easily tuned by varying the length of the tuning metal stubs. The equivalent circuit of the proposed MTM is modelled in Advanced Design Software (ADS) that exhibits a similar S21 compared with CST simulation. Surface current, electric and magnetic fields are analyzed to explain the frequency tuning property and other performances of the MTM. Compact size, ENG with near zero permeability and refractive index along with frequency selectivity through tuning provides flexibility for frequency selective applications of this MTM in wireless communications.
  2. Fulltext Lifestyle indices of body composition and obesity risk and prevalence among multi-ethnic adolescents in Malaysia
    Zulfarina MS, Sharif R, Mokhtar SA, Shuid AN, Naina-Mohamed I
    Front Pediatr, 2022;10:899014.
    PMID: 36389377 DOI: 10.3389/fped.2022.899014
    The prevalence of childhood obesity in Malaysia has doubled in less than a decade. Moreover, being overweight and obese have been associated with immediate and later comorbidities, thus emphasizing the need to prevent obesity from an early age. This cross-sectional study involved 923 multi-ethnic Malaysian adolescents aged between 15 and 17 years old. Body composition was estimated using bioelectrical impedance analysis. Body mass index (BMI) classification was based on the World Health Organization (WHO) growth reference and the International Obesity Task Force (IOTF) cut-off. Meanwhile, the Child Growth Foundation (CGF) body fat reference was used to classify adolescents' adiposity. Lifestyle indices including physical activity, sedentary behavior, supplement intake, smoking and alcohol status were assessed via questionnaires. A high prevalence of overweight/obesity among the adolescents was observed according to the CGF (26%), followed by that of the WHO (24%) and then the IOTF (23%) cut-off, with high concordance values between each pair. After adjustment, a significant association was found between physical activity (PAQ score) and lean mass (p = 0.027). No lifestyle determinant was found to be a significant predictor of fat percentage. A high sedentary level increased the likelihood of obesity (OR 3.0, p 
  3. Fulltext Occurrence and visual characterization of microplastics from Mahakam River at Tenggarong City, Indonesia
    Sukmono Y, Hadibarata T, Kristanti RA, Singh A, Al Farraj DA, Elshikh MS
    J Contam Hydrol, 2024 Nov;267:104440.
    PMID: 39396457 DOI: 10.1016/j.jconhyd.2024.104440
    Indonesia generates approximately 7.8 million tons of plastic waste annually, which 4.9 million tons is mismanaged. Presently, there is significant concern on microplastics (MPs) pollution in aquatic environment. The research on the prevalence of MPs in river systems are comparatively lower than the studies conducted on marine systems. The primary goal of this research was to look into the prevalence of MPs in the river water of Mahakam of Tenggarong City, Indonesia. To adequately represent this area, a meticulous selection method was used to find five separate sampling locations, with two stations at each location, positioned 200 m apart on opposite sides of the river. According to the study's findings, MPs has been observed in the range of 19.2 ± 1.8 to 58.5 ± 3.5 particles/l. Based on the MPs type, fragments (43.4 %) were the most common type of MPs found in water samples. Furthermore, 44.6 % of the MPs had size smaller than 1000 μm. The prevalent hues observed in the water samples were transparent and black, composing 75.6 % of overall formation. The determination of microplastic polymers employed Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy, revealing the presence of various type, such as polyethylene (PE) and polypropylene (PP).
  4. Influence of Adolescents' Physical Activity on Bone Mineral Acquisition: A Systematic Review Article
    Zulfarina MS, Sharkawi AM, Aqilah-S N ZS, Mokhtar SA, Nazrun SA, Naina-Mohamed I
    Iran J Public Health, 2016 Dec;45(12):1545-1557.
    PMID: 28053920
    BACKGROUND: This study conducted to examine and to provide a systematic literature over the influence of adolescents' physical activity (PA) in maximizing`s peak bone mass (PBM). PBM or the 'bone bank' is an important determinant in achieving healthy bone. PA is one of the bone's lifestyle contributors and high PBM is one of the major strategies for preventing osteoporosis.

    METHODS: A computerized literature search using Medline (Ovid) and Scopus were conducted to identify relevant observational studies on the influence of different level of PA on bone acquisition among the healthy adolescent population. All articles included, were limited to original articles and English language.

    RESULTS: Nine studies met the inclusion criteria. Reported bone outcomes were of bone mass, bone structure and bone strength. Eight studies showed positive association between adolescents' PA and high bone variables. The influence of PA may differ according to sex, skeletal sites and bone outcomes.

    CONCLUSION: This study supported the importance of increase adolescents' regular PA in optimizing PBM thus preventing osteoporosis at later life.

  5. Fulltext Design and development of a compact, wide-angle metamaterial electromagnetic energy harvester with multiband functionality and polarization-insensitive features
    Ullah N, Islam MS, Hoque A, Alzamil A, Soliman MS, Islam MT
    Sci Rep, 2024 Aug 16;14(1):19000.
    PMID: 39152247 DOI: 10.1038/s41598-024-69976-2
    This article presents a compact, wide-angle, polarization-insensitive metamaterial harvester that can efficiently harvest electromagnetic (EM) energy in the S, C, X, and Ku bands. The harvester's unit cell consists of a split ring resonator, two strip lines, and two split strip lines, giving it a total size of (10 × 10) mm2. Each split gap is filled with a 50 Ω resistive load. The input impedance of the harvester is precisely designed to match that of free space, allowing for efficient absorption of EM power and appropriate redirection towards the resistive loads. The harvester's performance is also evaluated for various polarization and incident angles, considering the Transverse Electric and Transverse Magnetic modes. The simulation results reveal that the proposed harvester exhibits a notably greater conversion efficiency of around > 95%. The simulation outcomes were carefully validated through experimental tests conducted in an anechoic chamber using a 3 × 3 cell array of the proposed design. This ensured the accuracy and reliability of the results. The strong correlation between the experimental data and the full-wave simulations strongly supports the effectiveness of the proposed harvester. Therefore, the demonstrated efficiency and compact size make it a perfect fit for energy harvesting systems in wireless sensor networks.
  6. Fulltext Polarization-selective metamaterial absorber using tailored Y-shaped SRR for UWB device and Doppler navigation aids applications
    Mahmud S, Chowdhury AR, Hannan S, Tariqul Islam M, Alshammari AS, Soliman MS
    Heliyon, 2024 Dec 15;10(23):e40102.
    PMID: 39669167 DOI: 10.1016/j.heliyon.2024.e40102
    In this paper, we present an unprecedented metamaterial absorber design exhibiting exceptional characteristics in electromagnetic wave absorption. The proposed bent Y-shaped structure, fabricated on an FR-4 substrate with copper patches, showcases remarkable performance across a diverse frequency spectrum. Through exhaustive simulations in CST, this design manifests eight distinct resonant frequencies, achieving absorption rates exceeding 90 % at each resonance. The resonances, strategically spanning from L-band (3.728 GHz) through S-band, C-band, X-band, Ku-band, and K-band up to 22.664 GHz, signify unparalleled versatility and efficacy in mitigating electromagnetic radiation. It investigates the equivalent circuit parameters of a proposed metamaterial absorber design, focusing on inductance (L), capacitance (C), and resistance (R). This paper investigates the applications of UWB devices at 3.728 GHz and Doppler navigation aids at the 13.4 GHz frequency as regulated by the Federal Communications Commission. It includes a discussion on near-zero refractive Index Metamaterials (NZRIM), highlighting their potential utilization in achieving extraordinary control over wave behaviour. Notably, the absorber's inherent polarization insensitivity fortifies its adaptability in various applications. Additionally, the metamaterial exhibits near-zero or negative permittivity, altering electric response, while simultaneously demonstrating permeability absolute zero throughout all frequency bands sparking new avenues for exploration and challenging conventional electromagnetic theories.
  7. Fulltext Dural tear post mastoidectomy repaired with Dura Gen
    Wong CY, Khairi MD, Mohamed SA, Irfan M
    Med J Malaysia, 2010 Dec;65(4):307-8.
    PMID: 21901952
    Dural exposure may occur during the course of thinning the tegmen tympani and tegmen mastoideum in mastoid procedure. If large area of dura is exposed or lacerated, cerebrospinal fluid and brain herniation may enter the mastoid cavity. We report a case of a patient with injured dura mater and tegmen mastoideum during mastoidectomy for chronic suppurative otitis media with cholesteatoma managed by using DuraGen. The dura mater and tegmen defect healed totally showing the success of the procedure. A collagen matrix like DuraGen is an option for repairing dural tear in mastoid region.
  8. Fulltext Isolation and characterization of novel microsatellite markers in commercial selected golden Malaysian arowana fish, Scleropages formosus (Osteoglossidae)
    Manoharan B, Sulaimen Z, Omar F, Othman RY, Mohamed SZ, Bhassu S
    Genet. Mol. Res., 2011;10(2):712-6.
    PMID: 21523650 DOI: 10.4238/vol10-2gmr944
    Malaysian arowana (dragonfish; Scleropages formosus) is an ancient osteoglossid fish from southeast Asia. Due to the high demand of the ornamental fish trade and because of habitat loss, the species is close to extinction. We isolated and characterized 10 polymorphic microsatellites of this species, using 5'-anchored PCR. The number of alleles at the 10 microsatellite loci ranged from 2 to 28, with a mean of 7.8/locus. The observed heterozygosity ranged from 0.03 to 0.93 (mean: 0.39), whereas the expected heterozygosity ranged from 0.03 to 0.94 (mean: 0.46). Seven microsatellites deviated from Hardy-Weinberg equilibrium, and three conformed to Hardy-Weinberg equilibrium and were in linkage equilibrium. These 10 novel microsatellites should facilitate studies of genetic diversity and population structure of arowana to help plan actions for the conservation of the indigenous Malaysian arowana.
  9. Evaluating the toxic and beneficial effects of jering beans (Archidendron jiringa) in normal and diabetic rats
    Shukri R, Mohamed S, Mustapha NM, Hamid AA
    J Sci Food Agric, 2011 Nov;91(14):2697-706.
    PMID: 21744354 DOI: 10.1002/jsfa.4516
    Jering (Archidendron jiringa) is eaten in the tropics and traditionally extolled for treating diabetes, high blood pressure and eliminating bladder stones. Jering contains an unusual amino acid-djenkolic acid (S,S'-methylenebiscysteine)-which may form sharp crystals in the urinary tract, causing pain and haematuria. This study evaluates the beneficial and toxic effects of dietary jering on tissues and organs in normal and diabetic rats.
  10. Antioxidative properties of Pandanus amaryllifolius leaf extracts in accelerated oxidation and deep frying studies
    Nor FM, Mohamed S, Idris NA, Ismail R
    Food Chem, 2008 Sep 15;110(2):319-27.
    PMID: 26049222 DOI: 10.1016/j.foodchem.2008.02.004
    The potential uses of Pandanus amaryllifolius leaf extract as a natural antioxidant were evaluated in refined, bleached and deodorized (RBD) palm olein, using accelerated oxidation and deep frying studies at 180°C from 0 to 40h. The extracts (optimum concentration 0.2%) significantly retarded oil oxidation and deterioration (P<0.05), comparably to 0.02% BHT in tests such as peroxide value, anisidine value, iodine value, free fatty acid, oxidative stability index (OSI), polar and polymer compound contents. In sensory evaluation studies, different batches of French fries were not significantly different (P<0.05) from one another for oiliness, crispiness, taste and overall acceptability when the same oil was used for up to the 40th hour of frying. P. amaryllifolius leaf extract, which had a polyphenol content of 102mg/g, exhibited an excellent heat-stable antioxidant property and may be a good natural alternative to existing synthetic antioxidants in the food industry.
  11. Fulltext CT appearances of Marjolin's ulcer in the left gluteal region of a young man
    Mohamed S, Abdullah B, Singh DA, Heng KS
    Biomed Imaging Interv J, 2006 Jul;2(3):e26.
    PMID: 21614240 DOI: 10.2349/biij.2.3.e26
    Chronic wounds and scar tissues are prone to skin cancer. In 1828, Jean-Nicholas Marjolin described the occurrence of tumours in post-traumatic scar tissue. He did not, however, identify the warty ulcers he described as malignant. It was Dupuytren, who about two years later, noted that these lesions were cancerous. The eponym was bestowed by Da Costa in 1903. Marjolin's ulcer no longer refers only to carcinomas secondary to burns and is classified as a malignancy that arises from previously traumatised, chronically inflamed, or scarred skin. It has been reported in relation to osteomyelitis, venous stasis ulcer, tropical ulcers, chronic decubitus ulcer, frostbite, pilonidal sinus, vaccination site, urinary fistula, hidradenitis suppurativa, skin graft donor site, gunshot wounds, puncture wounds, dog bites, and lupus rash. Early arising Marjolin's ulcer has rarely been described in literature. In this case report, we present the CT appearances of Marjolin's ulcer in the left gluteal region of a young man.
  12. Effect of powder to liquid ratio on tensile strength and glass transition temperature of alumina filled poly methyl methacrylate (PMMA) denture base material
    Mohamed SH, Arifin A, Mohd Ishak ZA, Nizam A, Samsudin AR
    Med J Malaysia, 2004 May;59 Suppl B:147-8.
    PMID: 15468861
    The aim of this study was to evaluate the mechanical properties and glass transition temperature (Tg) of a denture base material prepared from high molecular weight poly methyl methacrylate (PMMA) and alumina (Al2O3). The glass transition temperature was studied by using differential scanning calorimetry (DSC). The effect of powder-to-liquid ratio was investigated. The result showed that the tensile properties and the Tg were slightly effected by the powder-to-liquid ratio. The ratio of 2.2:1 by weight of powder to liquid was found to be the best ratio for mixing the material to give the best result in this formulation.
  13. Tensile strength and water absorption of alumina filled poly (methyl methacrylate) denture base material
    Nizam A, Mohamed SH, Arifin A, Mohd Ishak ZA, Samsudin AR
    Med J Malaysia, 2004 May;59 Suppl B:145-6.
    PMID: 15468860
    The aim of this study was to evaluate the tensile properties and water absorption of denture base material prepared from high molecular weight poly methyl methacrylate (PMMA) and alumina (Al2O3) as particulate filler. Specimens for mechanical testing were prepared by adding composite powder to the monomer followed by hand mixing as in dental laboratory procedure. The tensile strength of the prepared denture base material was slightly higher than commercial denture base material, while the water absorption was almost the same for all formulation of denture base materials.
  14. Mechanical and thermal properties of hydroxyaptite filled poly (methyl methacrylate) heat processed denture base material
    Mohamed SH, Arifin A, Mohd Ishak ZA, Nizam A, Samsudin AR
    Med J Malaysia, 2004 May;59 Suppl B:25-6.
    PMID: 15468801
    The aim of this study was to evaluate the effect of powder-to-liquid ratio on the glass transition temperature (Tg) and the tensile properties of denture base material prepared from poly (methyl methacrylate) (PMMA) and hydroxyapatite (HA) previously treated with 3-trimethoxysilylpropyl methacrylate (gamma-MPS). Specimens for mechanical testing were prepared by adding composites powder (PMMA, BPO and HA) to the monomer (MMA and EGDMA) followed by hand mixing as in dental laboratory description usage. The glass transition temperature was studied by using differential scanning calorimetry (DSC). It was observed that the tensile properties and the Tg were affected by the powder-to-liquid ratio. The mechanical characterization of the materials were performed by using single edge notch-tension (SEN-T) specimens; the fracture toughness was slightly higher in formulation which contained HA filler compared to commercial denture base material.
  15. Anxiety and Depression in Cancer Patients: The Association with Religiosity and Religious Coping
    Ng GC, Mohamed S, Sulaiman AH, Zainal NZ
    J Relig Health, 2017 Apr;56(2):575-590.
    PMID: 27287259 DOI: 10.1007/s10943-016-0267-y
    There is a lack of studies looking into religiosity and religious coping in cancer patient. In this cross-sectional study, we examined the religiosity using Duke University Religion Index, religious coping using Brief Religious Coping Scale, anxiety and depression based on Hospital Anxiety and Depression Scale among 200 cancer patients. The association between religiosity and religious coping with anxiety and depression was studied. The findings showed that subjects with anxiety or depression used more negative religious coping and had lower non-organization religiosity. Hence, measurements in reducing negative religious coping and encouraging religious activities could help to reduce psychological distress in cancer patients.
  16. Vasorelaxation induced by common edible tropical plant extracts in isolated rat aorta and mesenteric vascular bed
    Runnie I, Salleh MN, Mohamed S, Head RJ, Abeywardena MY
    J Ethnopharmacol, 2004 Jun;92(2-3):311-6.
    PMID: 15138017
    In this study, the vasodilatory actions of nine edible tropical plant extracts were investigated. Ipomoea batatas (sweet potato leaf), Piper betle (betel leaf), Anacardium occidentale (cashew leaf), Gynandropsis gynandra (maman leaf), Carica papaya (papaya leaf), and Mentha arvensis (mint leaf) extracts exhibited more than 50% relaxing effect on aortic ring preparations, while Piper betle and Cymbopogon citratus (lemongrass stalk) showed comparable vasorelaxation on isolated perfused mesenteric artery preparation. The vascular effect on the aortic ring preparations were mainly endothelium-dependent, and mediated by nitric oxide (NO) as supported by the inhibition of action in the presence of N(omega)-nitro-L-arginine (NOLA), an nitric oxide synthase (NOS) inhibitor, or by the removal of endothelium. In contrast, vasodilatory actions in resistance vessels (perfused mesenteric vascular beds) appear to involve several biochemical mediators, including NO, prostanoids, and endothelium-dependent hyperpolarizing factors (EDHFs). Total phenolic contents and antioxidant capacities varied among different extracts and found to be independent of vascular relaxation effects. This study demonstrates that many edible plants common in Asian diets to possess potential health benefits, affording protection at the vascular endothelium level.
  17. Dengue Maculopathy Associated with Choroidopathy and Pseudohypopyon: A Case Series
    Ng CWK, Tai PY, Oli Mohamed S
    Ocul Immunol Inflamm, 2018;26(5):666-670.
    PMID: 27929712 DOI: 10.1080/09273948.2016.1254804
  18. Erratum: Effects of citrus leaf extract on aortic vascular reactivity in hypertensive rats fed repeatedly heated vegetable oil
    Siti HN, Kamisah Y, Mohamed S, Jaarin K
    Appl Physiol Nutr Metab, 2019 07;44(7):804.
    PMID: 31237792 DOI: 10.1139/apnm-2019-0390
  19. Epicatechin and scopoletin-rich Morinda citrifolia leaf ameliorated leukemia via anti-inflammatory, anti-angiogenesis, and apoptosis pathways in vitro and in vivo
    Ahmadi N, Mohamed S, Sulaiman Rahman H, Rosli R
    J Food Biochem, 2019 07;43(7):e12868.
    PMID: 31353737 DOI: 10.1111/jfbc.12868
    The anti-leukemia mechanisms of Morinda citrifolia L. leaf extract were investigated on human Jurkat leukemia cells and in leukemia-induced BALB/c mice. The leukemia-induced mice were fed daily with the extract (100 or 200 mg/kg BW) and compared to ATRA (All-trans-retinoic-acid; 5 mg/kg BW). After 4 weeks' treatment, the extract (standardized to epicatechin and scopoletin), arrested Jurkat cell-cycle at the G0/G1 phase and activated the caspase-3 and caspase-8 (death-receptor extrinsic pathways). The extract dose-dependently reduced the blood and bone marrow myeloblasts levels of leukemia-induced mice; upregulated cancer suppressor genes CSF3, SOCS1, PTEN and TRP53; increased anti-inflammatory IL10 and IL4; downregulated anti-apoptotic or proliferation genes; decreased the pro-inflammatory NF-κβ; suppressed pro-angiogenesis VEGFA mRNA expressions, and restored the homeostatic immune or leukocytes levels. The extract directly ameliorated leukemia via cancer cells apoptosis, suppressed inflammation and angiogenesis; and mitigated bone marrow myeloblasts imbalance, without any observable toxicity on the animals. PRACTICAL APPLICATIONS: The scopoletin (coumarin) and epicatechin (flavonoid)-rich Morinda citrifolia (Noni) leaves may be used as functional food ingredient, vegetables, or dietary supplements to treat and suppress leukemia progression by directly killing the cancer cells and preventing new cancer cells development and bone marrow myeloblast imbalance in the bone marrow, without being toxic to normal cells. The M. citrifolia leaf extract suppressed inflammation, and potential metastasis by inhibiting new cancer-related blood vessel formation.
  20. Chronic toxicity evaluation of Morinda citrifolia fruit and leaf in mice
    Mohamad Shalan NAA, Mustapha NM, Mohamed S
    Regul Toxicol Pharmacol, 2017 Feb;83:46-53.
    PMID: 27871867 DOI: 10.1016/j.yrtph.2016.11.022
    Noni (Morinda citrifolia) leaf and fruit are used as food and medicine. This report compares the chronic toxicity of Noni fruit and edible leaf water extracts (two doses each) in female mice. The 6 months study showed the fruit extract produced chronic toxicity effects at the high dose of 2 mg/ml drinking water, evidenced through deteriorated liver histology (hepatocyte necrosis), reduced liver length, increased liver injury marker AST (aspartate aminotransferase) and albumin reduction, injury symptoms (hypoactivity, excessive grooming, sunken eyes and hunched posture) and 40% mortality within 3 months. This hepatotoxicity results support the six liver injury reports in humans which were linked to chronic noni fruit juice consumption. Both doses of the leaf extracts demonstrated no observable toxicity. The hepatotoxicity effects of the M. citrifolia fruit extract in this study is unknown and may probably be due to the anthraquinones in the seeds and skin, which had potent quinone reductase inducer activity that reportedly was 40 times more effective than l-sulforaphane. This report will add to current data on the chronic toxicity cases of Morinda citrifolia fruit. No report on the chronic toxicity of Morinda citrifolia fruit in animal model is available for comparison.
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