Displaying publications 21 - 34 of 34 in total

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  1. Fulltext Carbon nanotube-Yttrium iron garnet nanohybrid synthesized via chemical vapor deposition and its potential application in fabricated screen-printed patch antenna
    Hasan IH, Ismail I, Hamidon MN, Mustaffa MS, Abdullah NH, Shafiee FN
    Heliyon, 2024 Nov 30;10(22):e39966.
    PMID: 39584123 DOI: 10.1016/j.heliyon.2024.e39966
    Carbon nanotube-Yttrium iron garnet (CNT-YIG) nanohybrid has been successfully synthesized using chemical vapor deposition (CVD) with yttrium iron garnet (YIG) nanopowders as catalyst, ethanol as carbon stock, and argon as carrier gas. Carbon nanotube (CNT) was observed to have grown from the YIG nanopowders with bamboo-like structures of CNT at a synthesis temperature of 900 °C. FESEM and RAMAN characterization indicated that the CNT-YIG nanohybrid exhibited the growth of bamboo-like CNT with high graphitization. Further analysis of electrical properties showed that the CNT-YIG nanohybrid has exhibited conductivity due to the CNT growth. The nanohybrid in the form of powders was then mixed with an organic vehicle to produce thick film paste and screen-printed onto a substrate as the working material for patch antenna application. Initial measurements using VNA indicated that CNT-YIG nanohybrid gave significant results regarding return loss and bandwidth, proving that the materials could have great potential to enhance patch antenna performance due to their combined electrical and magnetic properties.
  2. Fulltext Enhancing the Decolorization of Methylene Blue Using a Low-Cost Super-Absorbent Aided by Response Surface Methodology
    Abdullah NH, Mohamed M, Mohd Shohaimi NA, Mat Lazim A, Abdul Halim AZ, Mohd Shukri N, et al.
    Molecules, 2021 Jul 22;26(15).
    PMID: 34361580 DOI: 10.3390/molecules26154430
    The presence of organic dyes from industrial wastewater can cause pollution and exacerbate environmental problems; therefore, in the present work, activated carbon was synthesized from locally available oil palm trunk (OPT) biomass as a low-cost adsorbent to remove synthetic dye from aqueous media. The physical properties of the synthesized oil palm trunk activated carbon (OPTAC) were analyzed by SEM, FTIR-ATR, and XRD. The concurrent effects of the process variables (adsorbent dosage (g), methylene blue (MB) concentration (mg/L), and contact time (h)) on the MB removal percentage from aqueous solution were studied using a three-factor three-level Box-Behnken design (BBD) of response surface methodology (RSM), followed by the optimization of MB adsorption using OPTAC as the adsorbent. Based on the results of the analysis of variance (ANOVA) for the three parameters considered, adsorbent dosage (X1) is the most crucial parameter, with an F-value of 1857.43, followed by MB concentration (X2) and contact time (X3) with the F-values of 95.60 and 29.48, respectively. Furthermore, the highest MB removal efficiency of 97.9% was achieved at the optimum X1, X2, and X3 of 1.5 g, 200 mg/L, and 2 h, respectively.
  3. Chitosan coated magnetic cellulose nanowhisker as a drug delivery system for potential colorectal cancer treatment
    Yusefi M, Shameli K, Lee-Kiun MS, Teow SY, Moeini H, Ali RR, et al.
    Int J Biol Macromol, 2023 Apr 01;233:123388.
    PMID: 36706873 DOI: 10.1016/j.ijbiomac.2023.123388
    Polysaccharide-based magnetic nanocomposites can eminently illuminate several attractive features as anticancer drug carriers. In this study, rice straw-based cellulose nanowhisker (CNW) was used as solid support for Fe3O4 nanofillers to synthesize magnetic CNW. Then, cross-linked chitosan-coated magnetic CNW for 5-fluorouracil carrier abbreviated as CH/MCNW/5FU. Fourier-transform infrared, X-Ray diffraction, and X-ray photoelectron spectroscopy analysis indicated successful fabrication and multifunctional properties of the CH/MCNW/5FU nanocomposites. In addition, CH/MCNW/5FU nanocomposites showed hydrodynamic diameter and zeta potential value of 181.31 ± 3.46 nm and +23 ± 1.8 mV, respectively. Based on images of transmission electron microscopy, magnetic CNW as reinforcement was coated with chitosan to obtain almost spherical CH/MCNW/5FU nanocomposites with an average diameter of 37.16 ± 3.08. The nanocomposites indicated desired saturation magnetization and thermal stability, high drug encapsulation efficiency, and pH-dependent swelling and drug release performance. CH/MCNW/5FU nanocomposites showed potent killing effects against colorectal cancer cells in both 2D monolayer and 3D spheroid models. These findings suggest CH/MCNW as a potential carrier for anticancer drugs with high tumour-penetrating capacity.
  4. Fulltext A global mandate to strengthen emergency, critical and operative care
    Tadesse L, Abdullah NH, Awadalla HMI, D'Amours S, Davies F, Kissoon N, et al.
    Bull World Health Organ, 2023 Apr 01;101(4):231-231A.
    PMID: 37008261 DOI: 10.2471/BLT.23.289916
  5. Fulltext Tracking the early depleting transmission dynamics of COVID-19 with a time-varying SIR model
    Law KB, Peariasamy KM, Gill BS, Singh S, Sundram BM, Rajendran K, et al.
    Sci Rep, 2020 12 10;10(1):21721.
    PMID: 33303925 DOI: 10.1038/s41598-020-78739-8
    The susceptible-infectious-removed (SIR) model offers the simplest framework to study transmission dynamics of COVID-19, however, it does not factor in its early depleting trend observed during a lockdown. We modified the SIR model to specifically simulate the early depleting transmission dynamics of COVID-19 to better predict its temporal trend in Malaysia. The classical SIR model was fitted to observed total (I total), active (I) and removed (R) cases of COVID-19 before lockdown to estimate the basic reproduction number. Next, the model was modified with a partial time-varying force of infection, given by a proportionally depleting transmission coefficient, [Formula: see text] and a fractional term, z. The modified SIR model was then fitted to observed data over 6 weeks during the lockdown. Model fitting and projection were validated using the mean absolute percent error (MAPE). The transmission dynamics of COVID-19 was interrupted immediately by the lockdown. The modified SIR model projected the depleting temporal trends with lowest MAPE for I total, followed by I, I daily and R. During lockdown, the dynamics of COVID-19 depleted at a rate of 4.7% each day with a decreased capacity of 40%. For 7-day and 14-day projections, the modified SIR model accurately predicted I total, I and R. The depleting transmission dynamics for COVID-19 during lockdown can be accurately captured by time-varying SIR model. Projection generated based on observed data is useful for future planning and control of COVID-19.
  6. Fulltext A Study on Microwave Absorption Properties of Carbon Black and Ni0.6Zn0.4Fe2O4 Nanocomposites by Tuning the Matching-Absorbing Layer Structures
    Ibrahim IR, Matori KA, Ismail I, Awang Z, Rusly SNA, Nazlan R, et al.
    Sci Rep, 2020 Feb 21;10(1):3135.
    PMID: 32081972 DOI: 10.1038/s41598-020-60107-1
    Microwave absorption properties were systematically studied for double-layer carbon black/epoxy resin (CB) and Ni0.6Zn0.4Fe2O4/epoxy resin (F) nanocomposites in the frequency range of 8 to 18 GHz. The Ni0.6Zn0.4Fe2O4 nanoparticles were synthesized via high energy ball milling with subsequent sintering while carbon black was commercially purchased. The materials were later incorporated into epoxy resin to fabricate double-layer composite structures with total thicknesses of 2 and 3 mm. The CB1/F1, in which carbon black as matching and ferrite as absorbing layer with each thickness of 1 mm, showed the highest microwave absorption of more than 99.9%, with minimum reflection loss of -33.8 dB but with an absorption bandwidth of only 2.7 GHz. Double layer absorbers with F1/CB1(ferrite as matching and carbon black as absorbing layer with each thickness of 1 mm) structure showed the best microwave absorption performance in which more than 99% microwave energy were absorbed, with promising minimum reflection loss of -24.0 dB, along with a wider bandwidth of 4.8 GHz and yet with a reduced thickness of only 2 mm.
  7. Fulltext The effects of super spreading events and movement control measures on the COVID-19 pandemic in Malaysia
    Herng LC, Singh S, Sundram BM, Zamri ASSM, Vei TC, Aris T, et al.
    Sci Rep, 2022 02 09;12(1):2197.
    PMID: 35140319 DOI: 10.1038/s41598-022-06341-1
    This paper aims to develop an automated web application to generate validated daily effective reproduction numbers (Rt) which can be used to examine the effects of super-spreading events due to mass gatherings and the effectiveness of the various Movement Control Order (MCO) stringency levels on the outbreak progression of COVID-19 in Malaysia. The effective reproduction number, Rt, was estimated by adopting and modifying an Rt estimation algorithm using a validated distribution mean of 3.96 and standard deviation of 4.75 with a seven-day sliding window. The Rt values generated were validated using thea moving window SEIR model with a negative binomial likelihood fitted using methods from the Bayesian inferential framework. A Pearson's correlation between the Rt values estimated by the algorithm and the SEIR model was r = 0.70, p 
  8. Larvicidal Effectiveness of Azolla pinnata against Aedes aegypti (Diptera: Culicidae) with Its Effects on Larval Morphology and Visualization of Behavioural Response
    Husna Zulkrnin NS, Rozhan NN, Zulkfili NA, Nik Yusoff NR, Rasat MSM, Abdullah NH, et al.
    J Parasitol Res, 2018;2018:1383186.
    PMID: 30050688 DOI: 10.1155/2018/1383186
    Dengue is vector-borne diseases with 390 million infections per year extending over 120 countries of the world. Aedes aegypti (L.) (Diptera: Culicidae) is a primary vector for dengue viral infections for humans. Current focus on application of natural product against mosquito vectors has been the main priority for research due to its eco-safety. The extensive use of chemical insecticides has led to severe health problems, environmental pollution, toxic hazards to human and nontarget species, and development of insecticide resistance on mosquitoes. Azolla pinnata is an aquatic fern and predominantly used as feed in poultry industry and as fertilizer in agricultural field for enhancing the fertility of rice paddy soil. The present study was conducted to explore the larvicidal efficacy of A. pinnata using fresh and powdered form against late third-stage larvae (6 days, 5 mm in larvae body length) of Ae. aegypti (L.) (Diptera: Culicidae). The larvicidal bioassays were performed using World Health Organization standard larval susceptibility test method for different concentration for powdered and fresh A. pinnata. Powdered A. pinnata concentration used during larvicidal bioassay ranges from 500ppm to 2000ppm; meanwhile, fresh A. pinnata ranges from 500ppm to 9,000,000 ppm. The highest mortality was at 1853 ppm for powdered A. pinnata compared with fresh A. pinnata at 2,521,535 ppm, while the LC50 for both powdered and fresh A. pinnata recorded at 1262 ppm and 1853 ppm, respectively. Finally, the analysis of variance (ANOVA) showed significant difference on Ae. aegypti larval mortality (F=30.439, df=1, p≤0.001) and concentration (F=20.002, df=1, p≤0.001) compared to powdered and fresh A. pinnata at 24-hour bioassay test. In conclusion, the powdered A. pinnata serves as a good larvicidal agent against Ae. aegypti (L.) (Diptera: Culicidae) and this study provided information on the lethal concentration that may have potential for a more eco-friendly Aedes mosquito control program.
  9. Fulltext International consensus recommendations for the optimal prioritisation and distribution of surgical services in low-income and middle-income countries: a modified Delphi process
    Henry JA, Reyes AM, Ameh E, Yip CH, Nthumba P, Mehes M, et al.
    BMJ Open, 2023 Jan 24;13(1):e062687.
    PMID: 36693687 DOI: 10.1136/bmjopen-2022-062687
    OBJECTIVES: To develop consensus statements regarding the regional-level or district-level distribution of surgical services in low and middle-income countries (LMICs) and prioritisation of service scale-up.

    DESIGN: This work was conducted using a modified Delphi consensus process. Initial statements were developed by the International Standards and Guidelines for Quality Safe Surgery and Anesthesia Working Group of the Global Alliance for Surgical, Obstetric, Trauma and Anesthesia Care (G4 Alliance) and the International Society of Surgery based on previously published literature and clinical expertise. The Guidance on Conducting and REporting DElphi Studies framework was applied.

    SETTING: The Working Group convened in Suva, Fiji for a meeting hosted by the Ministry of Health and Medical Services to develop the initial statements. Local experts were invited to participate. The modified Delphi process was conducted through an electronically administered anonymised survey.

    PARTICIPANTS: Expert LMIC surgeons were nominated for participation in the modified Delphi process based on criteria developed by the Working Group.

    PRIMARY OUTCOME MEASURES: The consensus panel voted on statements regarding the organisation of surgical services, principles for scale-up and prioritisation of scale-up. Statements reached consensus if there was ≥80% agreement among participants.

    RESULTS: Fifty-three nominated experts from 27 LMICs voted on 27 statements in two rounds. Ultimately, 26 statements reached consensus and comprise the current recommendations. The statements covered three major themes: which surgical services should be decentralised or regionalised; how the implementation of these services should be prioritised; and principles to guide LMIC governments and international visiting teams in scaling up safe, accessible and affordable surgical care.

    CONCLUSIONS: These recommendations represent the first step towards the development of international guidelines for the scaling up of surgical services in LMICs. They constitute the best available basis for policymaking, planning and allocation of resources for strengthening surgical systems.

  10. Fulltext Structural, Electromagnetic and Microwave Properties of Magnetite Extracted from Mill Scale Waste via Conventional Ball Milling and Mechanical Alloying Techniques
    Elmahaishi MF, Azis RS, Ismail I, Mustaffa MS, Abbas Z, Matori KA, et al.
    Materials (Basel), 2021 Nov 22;14(22).
    PMID: 34832475 DOI: 10.3390/ma14227075
    This study presents the utilization of mill scale waste, which has attracted much attention due to its high content of magnetite (Fe3O4). This work focuses on the extraction of Fe3O4 from mill scale waste via magnetic separation, and ball milling was used to fabricate a microwave absorber. The extracted magnetic powder was ground-milled using two different techniques: (i) a conventional milling technique (CM) and (ii) mechanical alloying (MM) process. The Fe3O4/CM samples were prepared by a conventional milling process using steel pot ball milling, while the Fe3O4/MM samples were prepared using a high-energy ball milling (HEBM) method. The effect of milling time on the structural, phase composition, and electromagnetic properties were examined using X-ray diffraction (XRD) and a vector network analyzer (VNA). XRD confirmed the formation of magnetite after both the magnetic separation and milling processes. The results revealed that Fe3O4 exhibited excellent microwave absorption properties because of the synergistic characteristics of its dielectric and magnetic loss. The results showed that the Fe3O4/CM particle powder had a greater absorption power (reflection loss:
  11. Fulltext Responding to the Potential of Ebola Virus Disease (EVD) Importation into Malaysia
    Wan Mohamed Noor WN, Sandhu SS, Ahmad Mahir HM, Kurup D, Rusli N, Saat Z, et al.
    Malays J Med Sci, 2014 Nov-Dec;21(6):3-8.
    PMID: 25897276 MyJurnal
    The current Ebola outbreak, which is the first to affect West African countries, has been declared to have met the conditions for a Public Health Emergency of International Concern (PHEIC) by the World Health Organization (WHO). Thus, the Ministry of Health (MOH) of Malaysia has taken steps to strengthen and enhanced the five core components of preparedness and response to mitigate the outbreak. The National Crisis Preparedness and Response Centre (CPRC) commands, controls and coordinates the preparedness and response plans for disasters, outbreaks, crises and emergencies (DOCE) related to health in a centralised way. Through standardised case definition and mandatory notification of Ebola by public and private practitioners, surveillance of Ebola is made possible. Government hospitals and laboratories have been identified to manage and diagnose Ebola virus infections, and medical staff members have been trained to handle an Ebola outbreak, with emphasis on strict infection prevention and control practices. Monitoring of the points of entry, focusing on travellers and students visiting or coming from West African countries is made possible by interagency collaborations. To alleviate the public's anxiety, effective risk communications are being delivered through various channels. With experience in past outbreak control, the MOH's preparedness and response plans are in place to abate an Ebola outbreak.
  12. Kinetics, Thermodynamics, and Mechanistic Studies of Arsenic Removal Utilizing Natural Soil as Adsorbent
    Mohd Fairuz FS, Md Muslim NZ, Wan Abdullah WN, Mohd Shohaimi NA, Abdullah NH, Ab Halim AZ, et al.
    Langmuir, 2024 Sep 11.
    PMID: 39261293 DOI: 10.1021/acs.langmuir.4c02309
    The contamination of water sources with the heavy metal contaminant arsenic (As) causes substantial risks to humans, animals, and other living organisms. Therefore, the introduction of methods for the removal of As is important. The present study aimed to investigate the adsorption model and mechanism of As removal utilizing natural soil adsorbents. The batch adsorption technique was used to analyze the impacts of various parameters such as contact time, initial As concentration, pH, and temperature. Adsorption mechanisms were studied through adsorption kinetic, isotherm, and thermodynamic models. The batch adsorption study findings indicate that the optimal conditions for maximum As removal were achieved by application of 2.2 g of adsorbents in 50 μg/L of As solution for 60 min of contact time at a pH of 5.5 ± 0.5 and a temperature of 40 °C. The highest removal efficiency was achieved when red soil was employed as the adsorbent. The kinetic, isotherm, and thermodynamic models revealed that As adsorption was a chemisorptive, nonspontaneous, and endothermic process.
  13. Fulltext PICK-ing Malaysia's Epidemic Apart: Effectiveness of a Diverse COVID-19 Vaccine Portfolio
    Suah JL, Tok PSK, Ong SM, Husin M, Tng BH, Sivasampu S, et al.
    Vaccines (Basel), 2021 Nov 24;9(12).
    PMID: 34960126 DOI: 10.3390/vaccines9121381
    Malaysia rolled out a diverse portfolio of predominantly three COVID-19 vaccines (AZD1222, BNT162b2, and CoronaVac) beginning 24 February 2021. We evaluated vaccine effectiveness with two methods, covering 1 April to 15 September 2021: (1) the screening method for COVID-19 (SARS-CoV-2) infection and symptomatic COVID-19; and (2) a retrospective cohort of confirmed COVID-19 cases for COVID-19 related ICU admission and death using logistic regression. The screening method estimated partial vaccination to be 48.8% effective (95% CI: 46.8, 50.7) against COVID-19 infection and 33.5% effective (95% CI: 31.6, 35.5) against symptomatic COVID-19. Full vaccination is estimated at 87.8% effective (95% CI: 85.8, 89.7) against COVID-19 infection and 85.4% effective (95% CI: 83.4, 87.3) against symptomatic COVID-19. Among the cohort of confirmed COVID-19 cases, partial vaccination with any of the three vaccines is estimated at 31.3% effective (95% CI: 28.5, 34.1) in preventing ICU admission, and 45.1% effective (95% CI: 42.6, 47.5) in preventing death. Full vaccination with any of the three vaccines is estimated at 79.1% effective (95% CI: 77.7, 80.4) in preventing ICU admission and 86.7% effective (95% CI: 85.7, 87.6) in preventing deaths. Our findings suggest that full vaccination with any of the three predominant vaccines (AZD1222, BNT162b2, and CoronaVac) in Malaysia has been highly effective in preventing COVID-19 infection, symptomatic COVID-19, COVID-19-related ICU admission, and death.
  14. Knema retusa is antibacterial and antibiofilm against antibiotic resistant Staphylococcus aureus and S. haemolyticus isolated in bovine mastitis
    Chuprom J, Kidsin K, Sangkanu S, Nissapatorn V, Wiart C, de Lourdes Pereira M, et al.
    Vet Res Commun, 2023 Jun;47(2):523-538.
    PMID: 36260188 DOI: 10.1007/s11259-022-09999-0
    This study aimed to assess antibacterial activity of Knema retusa wood extract (KRe) against antibiotic resistant staphylococci which are causative agents of bovine mastitis. From 75 cases of intramammary infections in dairy cows, 66 staphylococcal isolates were collected, including 11 Staphylococcus aureus isolates (17%) and 55 coagulase-negative staphylococci (83%). Sixty isolates (91%) formed strong biofilms. KRe had minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) against the isolates ranging 32-256 ug/mL and 64-512 ug/mL, respectively. Two-hour KRe exposures at 4×MIC, viabilities of S. aureus and S. haemolyticus decreased by 3 log10 compared to the control. Scanning EM (SEM) showed that KRe disrupted the bacterial cells of both species. KRe at 1/16×MIC significantly inhibited biofilm formation (P 
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