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  1. Fulltext Design of a plastic optical fibre waveguide coupler for a portable optical access card system
    Shaari, S., Ehsan, A.A., Abd-Rahman, M.K.
    ASM Science Journal, 2008;2(2):153-161.
    MyJurnal
    An optical code generating device for a portable optical access-card system was constructed using the plastic optical fibre (POF) waveguide coupler. The newly constructed device provided output light intensities which were used as optical codes in a portable optical access-card system. The construction of a basic 1 × 2 waveguide design combined two major components which were the asymmetric Y-junction splitter and the linear taper. A hollow waveguide structure was utilized as it provided more flexibility in guiding light rays. A basic 1 × 2 waveguide coupler was designed using the CAD tool and then the ray was traced using the non-sequential ray tracing tool. A linear relationship between the tap-off ratio and the waveguide tap-width enabled a higher-level hollow waveguide coupler to be designed using the simple cascading technique. Construction of a 1 × 4 and higher level waveguide coupler was easily realized using the basic 1 × 2 waveguide coupler design together with a simple cascading technique.
  2. Fulltext Structural, Morphological, and Electron Transport Studies of Annealing Dependent In2O3 Dye-Sensitized Solar Cell
    Mahalingam S, Abdullah H, Shaari S, Muchtar A, Asshari I
    ScientificWorldJournal, 2015;2015:403848.
    PMID: 26146652 DOI: 10.1155/2015/403848
    Indium oxide (In2O3) thin films annealed at various annealing temperatures were prepared by using spin-coating method for dye-sensitized solar cells (DSSCs). The objective of this research is to enhance the photovoltaic conversion efficiency in In2O3 thin films by finding the optimum annealing temperature and also to study the reason for high and low performance in the annealed In2O3 thin films. The structural and morphological characteristics of In2O3 thin films were studied via XRD patterns, atomic force microscopy (AFM), field-emission scanning electron microscopy (FESEM), EDX sampling, and transmission electron microscopy (TEM). The annealing treatment modified the nanostructures of the In2O3 thin films viewed through FESEM images. The In2O3-450 °C-based DSSC exhibited better photovoltaic performance than the other annealed thin films of 1.54%. The electron properties were studied by electrochemical impedance spectroscopy (EIS) unit. The In2O3-450 °C thin films provide larger diffusion rate, low recombination effect, and longer electron lifetime, thus enhancing the performance of DSSC.
  3. Fulltext Juxtarenal/pararenal Wilms' tumour in a six-year-old Malay girl
    Ngan KW, Shaari S, Subramaniam T
    Singapore Med J, 2009 Sep;50(9):e329-31.
    PMID: 19787163
    We report a six-year-old Malay girl who presented with a right retroperitoneal tumour that measured 7.5 cm in diameter. A wide excision of the lesion was performed. The tumour was separated from a normal-appearing right kidney by a capsule. Microscopically, this well-encapsulated tumour was composed of classical triphasic components: epithelial, mesenchymal and blastemal areas. The immunohistochemical study showed WT1 expression in the blastemal area. Thus, a diagnosis of Wilms' tumour with favourable histology was made. The patient was well for 12 months. Extrarenal Wilms' tumour is uncommon, with the majority of cases occurring in the retroperitoneal and inguinal areas. Wilms' tumour that is not arising from the intrarenal area but shares a common capsule with the ipsilateral kidney, is even rarer. Indeed, our case would be more appropriately classified as juxtarenal/pararenal Wilms' tumour. Despite its rarity, an extrarenal or even juxtarenal/pararenal Wilms' tumour should be included in the differential diagnosis of retroperitoneal tumour.
  4. Surface modification via wet chemical etching of single-crystalline silicon for photovoltaic application
    Reshak AH, Shahimin MM, Shaari S, Johan N
    Prog Biophys Mol Biol, 2013 Nov;113(2):327-32.
    PMID: 24139943 DOI: 10.1016/j.pbiomolbio.2013.10.002
    The potential of solar cells have not been fully tapped due to the lack of energy conversion efficiency. There are three important mechanisms in producing high efficiency cells to harvest solar energy; reduction of light reflectance, enhancement of light trapping in the cell and increment of light absorption. The current work represent studies conducted in surface modification of single-crystalline silicon solar cells using wet chemical etching techniques. Two etching types are applied; alkaline etching (KOH:IPA:DI) and acidic etching (HF:HNO3:DI). The alkaline solution resulted in anisotropic profile that leads to the formation of inverted pyramids. While acidic solution formed circular craters along the front surface of silicon wafer. This surface modification will leads to the reduction of light reflectance via texturizing the surface and thereby increases the short circuit current and conversion rate of the solar cells.
  5. Fulltext Development of phase detection schemes based on surface plasmon resonance using interferometry
    Kashif M, Bakar AA, Arsad N, Shaari S
    Sensors (Basel), 2014 Aug 28;14(9):15914-38.
    PMID: 25171117 DOI: 10.3390/s140915914
    Surface plasmon resonance (SPR) is a novel optical sensing technique with a unique ability to monitor molecular binding in real-time for biological and chemical sensor applications. Interferometry is an excellent tool for accurate measurement of SPR changes, the measurement and comparison is made for the sensitivity, dynamic range and resolution of the different analytes using interferometry techniques. SPR interferometry can also employ phase detection in addition to the amplitude of the reflected light wave, and the phase changes more rapidly compared with other approaches, i.e., intensity, angle and wavelength. Therefore, the SPR phase interferometer offers the advantages of spatial phase resolution and high sensitivity. This work discusses the advancements in interferometric SPR methods to measure the phase shifts due to refractive index changes. The main application areas of SPR sensors are demonstrated, i.e., the Fabry-Perot interferometer, Michelson interferometer and Mach-Zehnder interferometer, with different configurations. The three interferometers are discussed in detail, and solutions are suggested to enhance the performance parameters that will aid in future biological and chemical sensors.
  6. Fulltext Thermal Annealing Effect on Structural, Morphological, and Sensor Performance of PANI-Ag-Fe Based Electrochemical E. coli Sensor for Environmental Monitoring
    Mohammad Naim N, Abdullah H, Umar AA, Abdul Hamid A, Shaari S
    ScientificWorldJournal, 2015;2015:696521.
    PMID: 26078996 DOI: 10.1155/2015/696521
    PANI-Ag-Fe nanocomposite thin films based electrochemical E. coli sensor was developed with thermal annealing. PANI-Ag-Fe nanocomposite thin films were prepared by oxidative polymerization of aniline and the reduction process of Ag-Fe bimetallic compound with the presence of nitric acid and PVA. The films were deposited on glass substrate using spin-coating technique before they were annealed at 300 °C. The films were characterized using XRD, UV-Vis spectroscopy, and FESEM to study the structural and morphological properties. The electrochemical sensor performance was conducted using I-V measurement electrochemical impedance spectroscopy (EIS). The sensitivity upon the presence of E. coli was measured in clean water and E. coli solution. From XRD analysis, the crystallite sizes were found to become larger for the samples after annealing. UV-Vis absorption bands for samples before and after annealing show maximum absorbance peaks at around 422 nm-424 nm and 426 nm-464 nm, respectively. FESEM images show the diameter size for nanospherical Ag-Fe alloy particles increases after annealing. The sensor performance of PANI-Ag-Fe nanocomposite thin films upon E. coli cells in liquid medium indicates the sensitivity increases after annealing.
  7. Fulltext Recent Advances in Shape-Controlled Synthesis of Noble Metal Nanoparticles by Radiolysis Route
    Abedini A, Bakar AA, Larki F, Menon PS, Islam MS, Shaari S
    Nanoscale Res Lett, 2016 Dec;11(1):287.
    PMID: 27283051 DOI: 10.1186/s11671-016-1500-z
    This paper focuses on the recent advances on radiolysis-assisted shape-controlled synthesis of noble metal nanostructures. The techniques and protocols for producing desirable shapes of noble metal nanoparticles are discussed through introducing the critical parameters which can influence the nucleation and growth mechanisms. Nucleation rate plays a vital role on the crystallinity of seeds while growth rate of different seeds' facets determines the final shape of resultant nanoparticles. Nucleation and growth rate both can be altered with factors such as absorbed dose, capping agents, and experimental environment condition to control the final shape. Remarkable physical and chemical properties of synthesized noble metal nanoparticles by controlled morphology have been systematically evaluated to fully explore their applications.
  8. Opto-optical gain-clamped L-band erbium-doped fiber amplifier with C-band control signal
    Bakar AA, Mahdi MA, Al-Mansoori MH, Shaari S, Zamzuri AK
    Appl Opt, 2009 Apr 20;48(12):2340-3.
    PMID: 19381186
    We demonstrate an opto-optical gain-clamped L-band erbium-doped fiber amplifier by manipulating the C-band lasing wavelength as the control signal. The L-band gain-clamped value is achieved by tuning the control laser in the C-band wavelength range that propagates in the opposite direction to the L-band signal. Within the wavelength range of 1538 nm and 1560 nm, the L-band gain decreases linearly with the increment of the C-band lasing wavelength. The L-band gain dynamic range decreases with the increment of the cavity loss. By combining two different levels of cavity loss, the gain dynamic range of 10 dB from 11 dB to 21 dB is achieved with an average noise figure of less than 5.9 dB. The whole gain spectrum of the L-band can be used for multiple-channel amplification because the laser is created outside its signal band.
  9. Spectral amplitude coding OCDMA using and subtraction technique
    Hasoon FN, Aljunid SA, Samad MD, Abdullah MK, Shaari S
    Appl Opt, 2008 Mar 20;47(9):1263-8.
    PMID: 18709073
    An optical decoding technique is proposed for a spectral-amplitude-coding-optical code division multiple access, namely, the AND subtraction technique. The theory is being elaborated and experimental results have been done by comparing a double-weight code against the existing code, Hadamard. We have proved that the and subtraction technique gives better bit error rate performance than the conventional complementary subtraction technique against the received power level.
  10. Hepatitis B virus infection: Epidemiology and seroprevalence rate amongst Negrito tribe in Malaysia
    Sahlan N, Fadzilah MN, Muslim A, Shaari SA, Abdul Rahman T, Hoh BP
    Med J Malaysia, 2019 08;74(4):320-325.
    PMID: 31424040
    INTRODUCTION: Prevalence of Hepatitis B virus (HBV) infection among the non-indigenous people in Malaysia has been well established and range between 3% and 5%. However, data from the indigenous (Orang Asli) people is still lacking. The Negrito population is the most remotely located Orang Asli tribe with limited access to health care facilities. This study was undertaken to determine the epidemiology and seroprevalence of HBV infection among the Negrito.

    METHODS: Surveys were conducted in five Negrito settlements in Kelantan and Perak states in Malaysia. A total of 150 participants were recruited. Clinical history was taken and physical examination was performed. Five millilitres of whole blood were collected and tested for hepatitis B surface antigen (HBsAg) using electrochemiluminescence immunoassay.

    RESULTS: Participants were mainly from the Bateq (49.3%) and Mendriq (29.4%) sub-tribes. Overall, 13 subjects (8.7 %); nine males and four females were HBsAg positive. Nine of the HBsAg positive subjects were ≥35 years old. All of them had history of home deliver without evidence of antenatal record. Six (46%) of the HBsAg positive subjects had tattoo and body piercing in the past.

    CONCLUSION: The prevalence of HBV infection rate amongst the Negrito tribe is almost three-fold compared to the national rates. The reason for this finding remains unclear. Tattooing, body piercing and vertical transmission could be the main possible routes of transmission of HBV among the Negrito population in Malaysia.

  11. Fulltext Urea and creatinine detection on nano-laminated gold thin film using Kretschmann-based surface plasmon resonance biosensor
    Menon PS, Said FA, Mei GS, Berhanuddin DD, Umar AA, Shaari S, et al.
    PLoS One, 2018;13(7):e0201228.
    PMID: 30052647 DOI: 10.1371/journal.pone.0201228
    This work investigates the surface plasmon resonance (SPR) response of 50-nm thick nano-laminated gold film using Kretschmann-based biosensing for detection of urea and creatinine in solution of various concentrations (non-enzymatic samples). Comparison was made with the presence of urease and creatininase enzymes in the urea and creatinine solutions (enzymatic samples), respectively. Angular interrogation technique was applied using optical wavelengths of 670 nm and 785 nm. The biosensor detects the presence of urea and creatinine at concentrations ranging from 50-800 mM for urea samples and 10-200 mM for creatinine samples. The purpose of studying the enzymatic sample was mainly to enhance the sensitivity of the sensor towards urea and creatinine in the samples. Upon exposure to 670 nm optical wavelength, the sensitivity of 1.4°/M was detected in non-enzymatic urea samples and 4°/M in non-enzymatic creatinine samples. On the other hand, sensor sensitivity as high as 16.2°/M in urea-urease samples and 10°/M in creatinine-creatininase samples was detected. The enhanced sensitivity possibly attributed to the increase in refractive index of analyte sensing layer due to urea-urease and creatinine-creatininase coupling activity. This work has successfully proved the design and demonstrated a proof-of-concept experiment using a low-cost and easy fabrication of Kretschmann based nano-laminated gold film SPR biosensor for detection of urea and creatinine using urease and creatininase enzymes.
  12. Fulltext Investigation of graphene-on-metal substrates for SPR-based sensor using finite-difference time domain
    Said FA, Menon PS, Rajendran V, Shaari S, Majlis BY
    IET Nanobiotechnol, 2017 Dec;11(8):981-986.
    PMID: 29155398 DOI: 10.1049/iet-nbt.2017.0051
    In this study, the authors investigated the effects of a single layer graphene as a coating layer on top of metal thin films such as silver, gold, aluminum and copper using finite-difference time domain method. To enhance the resolution of surface plasmon resonance (SPR) sensor, it is necessary to increase the SPR reflectivity and decrease the full-width-half maximum (FWHM) of the SPR curve so that there is minimum uncertainty in the determination of the resonance dip. Numerical data was verified with analytical and experimental data where all the data were in good agreement with resonance angle differing in <10% due to noise present in components such as humidity and temperature. In further analysis, reflectivity and FWHM were compared among four types of metal with various thin film thicknesses where graphene was applied on top of the metal layers, and data was compared against pure conventional metal thin films. A 60 nm-thick Au thin film results in higher performance with reflectivity of 92.4% and FWHM of 0.88° whereas single layer graphene-on-60 nm-thick Au gave reflectivity of 91.7% and FWHM of 1.32°. However, a graphene-on-40 nm-thick Ag also gave good performance with narrower FWHM of 0.88° and reflection spectra of 89.2%.
  13. Fulltext Silicon Self-Switching Diode (SSD) as a Full-Wave Bridge Rectifier in 5G Networks Frequencies
    Yi Liang T, Zakaria NF, Kasjoo SR, Shaari S, Mohamad Isa M, Md Arshad MK, et al.
    Sensors (Basel), 2022 Dec 11;22(24).
    PMID: 36560080 DOI: 10.3390/s22249712
    The rapid growth of wireless technology has improved the network's technology from 4G to 5G, with sub-6 GHz being the centre of attention as the primary communication spectrum band. To effectively benefit this exclusive network, the improvement in the mm-wave detection of this range is crucial. In this work, a silicon self-switching device (SSD) based full-wave bridge rectifier was proposed as a candidate for a usable RF-DC converter in this frequency range. SSD has a similar operation to a conventional pn junction diode, but with advantages in fabrication simplicity where it does not require doping and junctions. The optimized structure of the SSD was cascaded and arranged to create a functional full-wave bridge rectifier with a quadratic relationship between the input voltage and outputs current. AC transient analysis and theoretical calculation performed on the full-wave rectifier shows an estimated cut-off frequency at ~12 GHz, with calculated responsivity and noise equivalent power of 1956.72 V/W and 2.3753 pW/Hz1/2, respectively. These results show the capability of silicon SSD to function as a full-wave bridge rectifier and is a potential candidate for RF-DC conversion in the targeted 5G frequency band and can be exploited for future energy harvesting application.
  14. Fulltext Prevalence and Associated Factors of Psychological Distress and Burnout among Medical Students: Findings from Two Campuses
    Arif NMNA, Roslan NS, Ismail SB, Nayak RD, Jamian MR, Mohamad Ali Roshidi AS, et al.
    Int J Environ Res Public Health, 2021 08 10;18(16).
    PMID: 34444193 DOI: 10.3390/ijerph18168446
    Medical training is intensive and predisposes students to psychological distress and burnout. Unaddressed burnout in medical training may persist in the internship phase and impact the quality of patient care. While some associations have been established, the link between some individual factors and training characteristics with distress and burnout in medical training remained unclear. In this study, we aim to examine the prevalence of psychological distress and burnout, and its association with gender, training phase, funding status, cumulative grade points average (CGPA), and coping strategies among medical students. The study applied a multicenter cross-sectional study design and convenience sampling on medical students from two medical schools from Malaysia and India. We used a self-reporting instrument that includes demographic details, the 12-item General Health Questionnaire (GHQ), the Copenhagen Burnout Inventory (CBI), and the Brief Coping Orientation to Problems Experienced (Brief COPE). A total of 748 medical students participated in the study. The prevalence of psychological distress, personal-related, work-related, and patient-related burnout were 33.0%, 56.1%, 35.0%, and 26.2%, respectively. Being male, clinical year, self-funded, and having a CGPA of more than 3.50 predicted psychological distress and burnout with mixed results. Maladaptive coping mechanisms consistently predicted the risk of psychological distress and burnout by more than two times. The findings indicate that primary and secondary mental health interventions have a role in medical training. A systematic intervention should incorporate coping skills training alongside institutional-targeted intervention.
  15. Systematic characterization and comparison of the CYP2C9 variability of the Orang Asli in Malaysia with 12 populations
    Teh LK, Subramaniam V, Tuan Abdu Aziz TA, Lee LS, Ismail MI, Yu CY, et al.
    Drug Metab. Pharmacokinet., 2016 Aug;31(4):304-13.
    PMID: 27325019 DOI: 10.1016/j.dmpk.2016.04.004
    We conducted a systematic characterization of CYP2C9 variants in 61 Orang Asli and 96 Singaporean Malays using the whole genome sequences data and compared the variants with the other 11 HapMap populations. The frequency of rs1057910 (CYP2C9*3) is the highest in the Orang Asli compared to other populations. Three alleles with clinical implication were detected in the Orang Asli while 2 were found in the Singaporean Malays. Large numbers of the Orang Asli are predicted to have reduced metabolic capacity and therefore they would require a lower dose of drugs which are metabolized by CYP2C9. They are also at increased risks of adverse effects and therapeutic failures. A large number of CYP2C9 variants in the Orang Asli were not in the Hardy Weinberg Equilibrium which could be due to small sample size or mutations that disrupt the equilibrium of allele frequencies. In conclusion, different polymorphism patterns, allele frequencies, genotype frequencies and LD blocks are observed between the Orang Asli, the Singaporean Malays and the other populations. The study provided new information on the genetic polymorphism of CYP2C9 which is important for the implementation of precision medicine for the Orang Asli.
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