Displaying publications 1 - 20 of 169 in total

  1. Karim, N.U., Sadzali, N.L., Hassan, M.
    The effects of squid ink at concentration of 0.10 and 0.25% on the total bacteria count and
    chemical spoilage indicator; total volatile basis nitrogen (TVBN) and trimethylamine (TMA)
    of squid (Loligo duvauceli) were analysed. The analysis were performed at interval of 5 days
    during 15 days of chilled storage (4°C). This studies also investigate the antioxidant capacity
    of the squid ink. The melanin-free squid ink were subjected to ferric reducing power (FRAP)
    and 2,2-diphenyl-1-picrylhydrazyl (DPPH) analysis. The FRAP values found in squid ink were
    0.04±0.01 µmole TE g-1 meanwhile DPPH values were recorded at 0.81±0.00 µmole TE g-1.
    The squid ink at both 0.10 and 0.25% concentration showed a significantly (p
  2. Kamarudin, K.H., Isa, M.I.N., Hassan, M.
    ASM Science Journal, 2018;11(101):29-36.
    Supercapacitors attract great interest among researchers as energy storage devices due to
    their high power capability and long cycle life. In this research, the electrochemical performance
    of electrical double layer capacitor (EDLC) based solid bio-polymer electrolyte
    (SBE) was studied. SBE consists of carboxymethyl cellulose (CMC) and ammonium nitrate
    (NH4NO3) was prepared by solution casting technique. The electrical impedance spectroscopy
    was used to verify the conductivity of SBE. The average conductivity was achieved
    at ∼ 10−3 S/cm. This research aims to prepare SBE and apply in the fabrication of EDLC.
    Scanning electron microscopy analysis showed the smooth and homogeneous surface of SBE
    film without any phase separation, while irregular shape and sizes of particles was found
    on the surface of electrode. Elemental identification results yielded that all corresponding
    elements presence in the SBE and electrode. The EDLC performance was characterized
    using galvanostatic charge-discharge at different constant currents. Charge-discharge studies
    showed that long discharge time (90 minutes) within 11 cycle was observed at 2µA. The
    highest specific capacitance of 1.8 F/g was discovered at 4µA. This study showed that EDLC
    based SBE has a promising potential to be applied in low current applications.
  3. Khormi HM, Kumar L
    Geospat Health, 2016 11 21;11(3):416.
    PMID: 27903054 DOI: 10.4081/gh.2016.416
    We used the Model for Interdisciplinary Research on Climate-H climate model with the A2 Special Report on Emissions Scenarios for the years 2050 and 2100 and CLIMEX software for projections to illustrate the potential impact of climate change on the spatial distributions of malaria in China, India, Indochina, Indonesia, and The Philippines based on climate variables such as temperature, moisture, heat, cold and dryness. The model was calibrated using data from several knowledge domains, including geographical distribution records. The areas in which malaria has currently been detected are consistent with those showing high values of the ecoclimatic index in the CLIMEX model. The match between prediction and reality was found to be high. More than 90% of the observed malaria distribution points were associated with the currently known suitable climate conditions. Climate suitability for malaria is projected to decrease in India, southern Myanmar, southern Thailand, eastern Borneo, and the region bordering Cambodia, Malaysia and the Indonesian islands, while it is expected to increase in southern and south-eastern China and Taiwan. The climatic models for Anopheles mosquitoes presented here should be useful for malaria control, monitoring, and management, particularly considering these future climate scenarios.
  4. Al-Ta'ii HMJ, Rmadhan EJ
    Appl Radiat Isot, 2021 Dec;178:109933.
    PMID: 34537565 DOI: 10.1016/j.apradiso.2021.109933
    Samples of cellulose nitrate polymer (CN-85) were annealed at 100 °C, 120 °C, and 140 °C for 15 min before and after irradiation with alpha particles emitted from a241Am source. Irradiation was performed at room temperature for 5 min. The changes in the optical and structural properties of CN-85 NTD, due to annealing and irradiation, were studied by using ultraviolet-visible spectroscopy (UV-VIS), and Fourier transform infrared spectroscopy (FTIR). Direct and indirect energy gap values, the number of carbon atoms, carbon clusters, and Urbach's energy values were determined. The UV-VIS analysis showed a shift in the absorption edge of the CN-85 polymer toward long wavelengths. The FTIR results revealed the changes in some bonds and the structural decomposition of CN-85 due to irradiation. The direct band gap energy was slightly decreased from 4.13 eV to 4.09 eV when the pristine samples were heated to 140 °C and irradiated. The indirect band gap energy was decreased from 3.9 eV to 3.8 eV under the same conditions. The Urbach's energy values showed a fluctuating rise with increasing annealing temperature for the irradiated and heated samples. When the pristine samples irradiated and heated, the band gap energy is reduced from 4.13 eV to 4.06 eV and from 3.90 eV to 3.84 eV for the direct and indirect transition, respectively. In conclusion, this technique showed promising benefits for a wide range of applications such as optoelectronics and microelectronic devices.
  5. Hassan MH
    Med J Malaysia, 2004 May;59 Suppl B:164-5.
    PMID: 15468869
    There has been, and is still, concern about the high elastic modulus of Ti alloys compared to bone. Any reduction in the Young's modulus value of the implant is expected to enhance stress redistribution to the adjacent bone tissues, minimize stress shielding and eventually prolong device lifetime. Dynamic Monte Carlo simulation is used to predict the gradual reduction in Young's modulus values between the bulk of Ti alloys and the modified surface layers due to Ca ion implantation. The simulation can be used as a screening step when applying new alloys and/or coatings.
  6. Aizat WM, Hassan M
    Adv Exp Med Biol, 2018 11 2;1102:31-49.
    PMID: 30382567 DOI: 10.1007/978-3-319-98758-3_3
    Proteomics is the study of proteins, the workhorses of cells. Proteins can be subjected to various post-translational modifications, making them dynamic to external perturbation. Proteomics can be divided into four areas: sequence, structural, functional and interaction and expression proteomics. These different areas used different instrumentations and have different focuses. For example, sequence and structural proteomics mainly focus on elucidating a particular protein sequence and structure, respectively. Meanwhile, functional and interaction proteomics concentrate on protein function and interaction partners, whereas expression proteomics allows the cataloguing of total proteins in any given samples, hence providing a holistic overview of various proteins in a cell. The application of expression proteomics in cancer and crop research is detailed in this chapter. The general workflow of expression proteomics consisting the use of mass spectrometry instrumentation has also been described, and some examples of proteomics studies are also presented.
  7. Alabid AH, Ibrahim MI, Hassali MA
    J Clin Diagn Res, 2014 Jan;8(1):119-23.
    PMID: 24596741 DOI: 10.7860/JCDR/2014/6199.3923
    BACKGROUND: In Malaysia, doctors in private clinics (often called dispensing doctors) are permitted to dispense medicines. This potentially may compromise rational dispensing of medicines in general and antibiotics in particular.
    AIM: This study explored, assessed and compared dispensing of antibiotics between Community Pharmacist (CP) and General Practitioners (GPs) regarding symptomatic diagnosis, antibiotic categories, adherence to therapeutic doses and promotion of generic antibiotics.
    METHOD: The study used trained Simulated Patients (SPs), who used a scenario of common cold symptoms at GP private clinics and community pharmacies to observe and explore the practice of antibiotics dispensing. The study was conducted within the period of May to September 2011 in Penang, Malaysia. The data was analysed using descriptive statistics, Chi-square and Fisher's Exact Tests at alpha level of 0.05.
    RESULTS: GPs dispensed more antibiotics than CPs (p= 0.001) for common cold symptoms. They dispensed more Amoxicillin (n = 14, 35%) than CPs (n = 11, 11%) (p < 0.001) and more Tetracycline (n = 3, 7.5%) while no CP dispensed this category (p = 0.022). On the other hand, CPs (n = 11, 11%) suggested brand antibiotics where as GPs dispensed only generic antibiotics (p < 0.001). Generally GPs comply better with the symptomatic diagnosis standard e.g. when asking SPs about the symptoms they had, all GPs (n = 40, 100%) complied better with this standard. Despite that, they dispensed more antibiotics (n = 26, 65%) than CPs (n = 29, 29%) (p = 0.001). GPs (n = 22, 55%) also are better than CPs (n = 16, 16%) in adherence to therapeutic doses (p< 0.001).
    CONCLUSION: Findings showed poor adherence to rational dispensing of antibiotics by both providers. Although, GPs adhere better to symptomatic diagnosis and therapeutic dosing of antibiotics than CPs, they unnecessarily prescribe and dispense more antibiotics for Upper respiratory tract infection (URTI) symptoms. Establishing prescription guidance and regulatory actions, especially for URTIs treatment, and separating of medication dispensing are seemed to be crucial steps for the reform.
    KEYWORDS: Community pharmacists; Dispensing doctors; Dispensing separation; General practitioners; Simulated patients ligament
  8. Alabid AH, Ibrahim MI, Hassali MA
    J Clin Diagn Res, 2013 Dec;7(12):2912-6.
    PMID: 24551673 DOI: 10.7860/JCDR/2013/6198.3789
    BACKGROUND: Malaysia, a South East Asian country, legally permits general medical practitioners in private clinics to dispense medicines. This possibly can dilute the pharmacist role in the provision of healthcare and pharmaceutical care and deprive patients to benefit from these services.
    OBJECTIVE: This study explored, assessed and compared the current status of medicines labeling, patient's counseling, and symptomatic diagnosis by general practitioners and community pharmacists.
    MATERIAL AND METHODS: This study used trained Simulated Patients (SP), who participated in a scenario of common cold symptoms at private clinics and community pharmacies. SPs explored medication labeling, patients counseling and symptomatic diagnosis undertaken by general practitioners and community pharmacists. Later, study authors assessed and compared these practices. The study was conducted during June 2011 in Penang, Malaysia.
    RESULTS: The study used descriptive statistics and Fisher-exact test to analyze data. Regarding patients counseling standard, among 100 visits by simulated patients, 64 (64%) from community pharmacists provided information about the medicine name, its indication, dosage and route of administration versus 17 (42.5%) general practitioners during 40 visits (p=0.024). Concerning adherence to labeling standard, for instance, only in one pharmacy visit, (1%) the pharmacist wrote the name of the patient on the medication label versus in 32 (80%) of doctors' visits, the doctors adhered to this labeling standard (p<0.001). In all doctors' visits (n=40, 100%), SPs were asked about symptoms, whereas in 87 (87%) CPs' visits, pharmacists fulfilled this counseling standard (p=0.02).
    CONCLUSION: Although pharmacists showed less compliance to medicine labeling and symptomatic diagnosis compared to doctors, their counseling of patients was better. Separation will definitely contribute to more concentration of each provider on his/her roles and improve and direct the experiences and skills towards being more patient oriented.
    KEYWORDS: Common cold; Community pharmacists; Dispensing doctors; Dispensing separation; General medical practitioners; Malaysia; Medicine labelling; Patient’s counselling; Simulated patients
  9. Farh HMH, Eltamaly AM, Othman MF
    PLoS One, 2018;13(11):e0206171.
    PMID: 30388119 DOI: 10.1371/journal.pone.0206171
    Particle Swarm Optimization (PSO) is widely used in maximum power point tracking (MPPT) of photovoltaic (PV) energy systems. Nevertheless, this technique suffers from two main problems in the case of partial shading conditions (PSCs). The first problem is that PSO is a time invariant optimization technique that cannot follow the dynamic global peak (GP) under time variant shading patterns (SPs) and sticks to the first GP that occurs at the beginning. This problem can be solved by dispersing the PSO particles using two new techniques introduced in this paper. The two new proposed PSO re-initialization techniques are to disperse the particles upon the SP changes and the other one is upon a predefined time (PDT). The second problem is regarding the high oscillations around steady state, which can be solved by using fuzzy logic controller (FLC) to fine-tune the output power and voltage from the PV system. The new contribution of this paper is the hybrid PSO-FLC with two PSO particles dispersing techniques that is able to solve the two previous mentioned problems effectively and improve the performance of the PV system in both normal and PSCs. A detailed list of comparisons between hybrid PSO-FLC and original PSO using the two proposed methodologies are achieved. The results prove the superior performance of hybrid PSO-FLC compared to PSO in terms of efficiency, accuracy, oscillations reduction around steady state and soft tuning of the GP tracked.
  10. Hassan MA, Mahmoodian R, Hamdi M
    Sci Rep, 2014;4:3724.
    PMID: 24430621 DOI: 10.1038/srep03724
    A modified smoothed particle hydrodynamic (MSPH) computational technique was utilized to simulate molten particle motion and infiltration speed on multi-scale analysis levels. The radial velocity and velocity gradient of molten alumina, iron infiltration in the TiC product and solidification rate, were predicted during centrifugal self-propagating high-temperature synthesis (SHS) simulation, which assisted the coating process by MSPH. The effects of particle size and temperature on infiltration and solidification of iron and alumina were mainly investigated. The obtained results were validated with experimental microstructure evidence. The simulation model successfully describes the magnitude of iron and alumina diffusion in a centrifugal thermite SHS and Ti + C hybrid reaction under centrifugal acceleration.
  11. Hassan MA, Hamdi M, Noma A
    J Mech Behav Biomed Mater, 2012 Jan;5(1):99-109.
    PMID: 22100084 DOI: 10.1016/j.jmbbm.2011.08.011
    The mechanical behavior of the heart muscle tissues is the central problem in finite element simulation of the heart contraction, excitation propagation and development of an artificial heart. Nonlinear elastic and viscoelastic passive material properties of the left ventricular papillary muscle of a guinea pig heart were determined based on in-vitro precise uniaxial and relaxation tests. The nonlinear elastic behavior was modeled by a hypoelastic model and different hyperelastic strain energy functions such as Ogden and Mooney-Rivlin. Nonlinear least square fitting and constrained optimization were conducted under MATLAB and MSC.MARC in order to obtain the model material parameters. The experimental tensile data was used to get the nonlinear elastic mechanical behavior of the heart muscle. However, stress relaxation data was used to determine the relaxation behavior as well as viscosity of the tissues. Viscohyperelastic behavior was constructed by a multiplicative decomposition of a standard Ogden strain energy function, W, for instantaneous deformation and a relaxation function, R(t), in a Prony series form. The study reveals that hypoelastic and hyperelastic (Ogden) models fit the tissue mechanical behaviors well and can be safely used for heart mechanics simulation. Since the characteristic relaxation time (900 s) of heart muscle tissues is very large compared with the actual time of heart beating cycle (800 ms), the effect of viscosity can be reasonably ignored. The amount and type of experimental data has a strong effect on the Ogden parameters. The in vitro passive mechanical properties are good initial values to start running the biosimulation codes for heart mechanics. However, an optimization algorithm is developed, based on clinical intact heart measurements, to estimate and re-correct the material parameters in order to get the in vivo mechanical properties, needed for very accurate bio-simulation and for the development of new materials for the artificial heart.
  12. Achanna S, Monga D, Hassan MS
    J Obstet Gynaecol Res, 1996 Apr;22(2):107-9.
    PMID: 8697337
    Acute abdominal pain during pregnancy presents a dilemma as signs and symptoms are often modified. Abdominal massage by traditional birth attendants (TBAs') during early labour is a common practice in the rural population, as it is perceived to give a soothening effect to the labouring mother. Many instances of abruptio placentae were reported in the past by this procedure, and in this case, the clinical picture presented as an abruptio placenta. Malpresentation and failure to progress were the indications for caesarean section despite the fetal demise. Severe post partum haemorrhage and failure to contract despite massive oxytocics resulted in the hysterectomy of the gravid horn, leaving the other horn intact.
  13. Hassan M, Patel DK, Subrayan V
    Ann Ophthalmol (Skokie), 2009;41(3-4):203-5.
    PMID: 20214058
    We present a case of a newly acquired herpetic infection in the graft after penetrating keratoplasty.
  14. Hassan M, Sulaiman MH, Lian CJ
    Acta Trop, 2013 May;126(2):142-5.
    PMID: 23416121 DOI: 10.1016/j.actatropica.2013.02.001
    A parasitological survey of 16 pangolins, confiscated from the Department of Wildlife and Nature Park Peninsular Malaysia (DWNP) at Kelantan and Pulau Pinang, Malaysia was conducted in 2011. Amblyomma javanense (family: Ixodidae) was the only ectoparasite found on the pangolins. The prevalence, intensity and life cycle of A. javanense were observed together with the respective pangolins' age and sex. It was found that 68.8% of the pangolins were infected, and significant difference, χ(2)(1, N=16)=4.02, p=0.05 were observed with males higher in infestation (88.9%) as compared to the females (42.9%). However, the mean intensity was higher on females (72) as compared to males (31.6). In addition, significant difference, χ(2) (2, N=16)=6.73, p=0.05 was recorded between adults and juveniles with juveniles found to be 100% infected as compared to adult (63.6%). Nevertheless, the mean intensity was slightly higher on adults (47) than juveniles (35). Adult ticks were found in higher numbers as compared to the nymph and larvae with number of male ticks higher (236) as compared to the females (53). Similarly, a high significant difference χ(2)(2, N=469)=203.47, p=0.05 was recorded in the composition of the tick's life stages with a higher number of adult ticks (61.6%) followed by nymph (30.3%) and larvae (8.1%). As such, the results of this study revealed a picture of the A. javanense life cycle which is related to the age and gender of the Malayan Pangolin.
  15. Mahmoodian R, Hamdi M, Hassan MA, Akbari A
    PLoS One, 2015;10(6):e0130836.
    PMID: 26111217 DOI: 10.1371/journal.pone.0130836
    Titanium carbide-graphite (TiC/C) composite was successfully synthesized from Ti and C starting elemental powders using self-propagating high-temperature synthesis technique in an ultra-high plasma inert medium in a single stage. The TiC was exposed to a high-temperature inert medium to allow recrystallization. The product was then characterized using field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Rietveld refinement, nanoindentation, and micro-hardness to determine the product's properties. The recorded micro-hardness of the product was 3660 HV, which is a 14% enhancement and makes is comparable to TiC materials.
  16. Bundhoo MA, Mohee R, Hassan MA
    J Environ Manage, 2015 Jul 1;157:20-48.
    PMID: 25881150 DOI: 10.1016/j.jenvman.2015.04.006
    Biohydrogen production from dark fermentation of lignocellulosic materials represents a huge potential in terms of renewable energy exploitation. However, the low hydrogen yield is currently hindering its development on industrial scale. This study reviewed various technologies that have been investigated for enhancing dark fermentative biohydrogen production. The pre-treatment technologies can be classified based on their applications as inoculum or substrates pre-treatment or they can be categorised into physical, chemical, physicochemical and biological based on the techniques used. From the different technologies reviewed, heat and acid pre-treatments are the most commonly studied technologies for both substrates and inoculum pre-treatment. Nevertheless, these two technologies need not necessarily be the most suitable since across different studies, a wide array of other emerging techniques as well as combined technologies have yielded positive findings. To date, there exists no perfect technology for either inoculum or substrate pre-treatment. Although the aim of inoculum pre-treatment is to suppress H2-consumers and enrich H2-producers, many sporulating H2-consumers survive the pre-treatment while some non-spore H2-producers are inhibited. Besides, several inoculum pre-treatment techniques are not effective in the long run and repeated pre-treatment may be required for continuous suppression of H2-consumers and sustained biohydrogen production. Furthermore, many technologies employed for substrates pre-treatment may yield inhibitory compounds that can eventually decrease biohydrogen production. Consequently, much research needs to be done to find out the best technology for both substrates and inoculum pre-treatment while also taking into consideration the energetic, economic and technical feasibility of implementing such a process on an industrial scale.
  17. Kee CY, Hassan M, Ramachandran KB
    PMID: 10595438
    The objective of this research was to study the kinetics of synthesis of a commercially important ester - Isopropyl Palmitate (IPP) using immobilized lipase (Lipozyme IM). It was studied in a packed bed differential reactor. In order to establish the kinetics of the reaction, parameters such as linear velocity of the fluid through the reactor, particle size, substrate concentration, substrate molar ratio, temperature and water activity were studied. Operational and storage stability of the enzyme were also assessed. The reaction followed Michaelis-Menton kinetics as observed from the relationship of initial rate of the reaction as a function of substrate concentration. It was found that the optimum substrate concentration was 0.15M palmitic acid and isopropyl alcohol in 1:1 stoichiometric ratio. Inhibition by excess of isopropyl alcohol has been identified. The optimum temperature for the esterification reaction was found to be around 50 degrees C. The activation energy of this process was determined to be 43.67 kJ/mol. The optimum water content was 0.50%. The reaction rates were measured in the absence of any significant external diffusional limitations. Since internal diffusional limitations could not be eliminated, the kinetics observed is only apparent.
  18. Quah BS, Razak AR, Hassan MH
    Acta Paediatr Jpn, 1997 Jun;39(3):329-35.
    PMID: 9241894
    The prevalence and severity of asthma, rhinitis and eczema in Kelantanese schoolchildren were determined as part of an international study of the epidemiology of asthma and allergic diseases. The international study of asthma and allergies in childhood (ISAAC) written questionnaire was administered to 7055 schoolchildren from February 1995 to August 1995. The respondents were parents or guardians of 5- to 7-year-old children (n = 3939), and schoolchildren aged 12-14 years (n = 3116). The ISAAC video questionnaire (AVQ3.0) was shown to children aged 12-14 years after the written questionnaire. The overall prevalences of 'ever wheezed' and 'wheezing in last 12 months' were 9.4 and 6.0% respectively. The prevalence of 'ever diagnosed with asthma' was 9.4%. Both 'ever wheezed' and 'wheezing in the last 12 months' were significantly higher in 12- to 14-year-old children than in 5- to 7-year-old children, with P values of 0.0006 and 0.014 respectively. No gender differences in the prevalences were observed. For the complete study group, 4.7% of children had sleep disturbed by wheezing but only 1.1% had a severe attack limiting speech in the preceding 12 months. Sleep disturbance was more common in the 12- to 14-year-old children than in 5- to 7-year-old children (P = 0.006). There was no difference between the age groups for severe attacks limiting speech. The overall prevalence of rhinitis and eczema symptoms were 27 and 12%, respectively. The prevalence of rhinitis in the 12-14 year age group (38.2%) was significantly higher (P < 0.0001) than in the 5-7 year age group (18.2%). The prevalence of eczema in the 5-7 year age group (13.7%) was significantly higher (P = < 0.0001) than in the 12-14 year age group (9.9%). These prevalence data are comparable with previous reports in Malaysian children, but are considerably lower than those reported for most developed countries.
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