Displaying publications 41 - 60 of 290 in total

Abstract:
Sort:
  1. Ishak R, Mohamed AB, Hassan K
    Malays J Reprod Health, 1990 Jun;8(1):1-4.
    PMID: 12316339
    A study was conducted on a total of 100 women attending the Family Planning Clinic in Kuala Lumpur. 50 took combined low-dose estrogen and progesterone pills for a year or more and the other 50 used different methods of birth control. Platelet aggregation, ATP release, Thromboxane B2, and 6-keto-prostaglandin F1alpha estimations were made to evaluate the effect of oral contraceptives (OCs) on platelet function and prostanoid production. The results showed no significant differences in the parameters measured in the 2 groups investigated. These findings are comparable to those reported by other studies, suggesting relatively low risk, if any, of thrombosis in OC users.
  2. Tengku Hashim TJ, Mohamed A
    PLoS One, 2017;12(10):e0177507.
    PMID: 28991919 DOI: 10.1371/journal.pone.0177507
    The growing interest in distributed generation (DG) in recent years has led to a number of generators connected to a distribution system. The integration of DGs in a distribution system has resulted in a network known as active distribution network due to the existence of bidirectional power flow in the system. Voltage rise issue is one of the predominantly important technical issues to be addressed when DGs exist in an active distribution network. This paper presents the application of the backtracking search algorithm (BSA), which is relatively new optimisation technique to determine the optimal settings of coordinated voltage control in a distribution system. The coordinated voltage control considers power factor, on-load tap-changer and generation curtailment control to manage voltage rise issue. A multi-objective function is formulated to minimise total losses and voltage deviation in a distribution system. The proposed BSA is compared with that of particle swarm optimisation (PSO) so as to evaluate its effectiveness in determining the optimal settings of power factor, tap-changer and percentage active power generation to be curtailed. The load flow algorithm from MATPOWER is integrated in the MATLAB environment to solve the multi-objective optimisation problem. Both the BSA and PSO optimisation techniques have been tested on a radial 13-bus distribution system and the results show that the BSA performs better than PSO by providing better fitness value and convergence rate.
  3. Mohamed AK, Tang YC
    Med J Malaysia, 2023 Dec;78(7):893-896.
    PMID: 38159924
    INTRODUCTION: Novel coronavirus 19 disease (COVID-19) pandemic poses healthcare providers challenges in the endoscopic suite. It is unclear whether it affects the endoscopic manifestations of upper gastrointestinal (GI) bleeding. This retrospective study was done to review demographic data, site of lesions and need of interventions for those lesions.

    MATERIALS AND METHODS: Oesophagoduodenoscopy (OGDS) reports of COVID-19 patients with indication of upper GI bleeding from March 2021 to April 2022 were reviewed. Data of 35 patients were then analysed.

    RESULTS: Of the 35 patients, 8.6% (n = 3) were female and 91.4% (n = 32) were males. A total of 31.4% (n = 11) were below 50 years and 68.6% (n = 24) were 50 and above. 34.3% (n = 12) with lesions requiring endoscopic intervention, 34.3% (n = 12) with lesions not requiring endoscopic intervention, 31.4% (n = 11) has no significant stigmata of recent haemorrhage. Among subgroup requiring endoscopic intervention, 50% (n = 6) are non-variceal bleeding (NVUIB), and 50% (n = 6) are variceal bleeding (VUGIB). Among NVUGIB, 16.7% (n = 1) is gastric and duodenal angiodysplasia requiring argon plasma coagulation, 50% (n = 3) are duodenal F2A ulcer requiring thermoablation, 16.7% (n = 1) is gastric F2A ulcer requiring hemoclip, and 16.6% (n = 1) is Cameron's ulcer requiring hemoclip. Among VUGIB, 100% (n = 6) are oesophageal varices requiring endoscopic variceal banding (EVL).

    CONCLUSIONS: Lower proportion of NVUGIB among COVID-19 patients raises hypothesis on whether prothrombotic state of COVID-19 is a protective factor of NVUGIB. Studies with larger sample size are needed to establish significance.

  4. Abualsaud K, Mahmuddin M, Saleh M, Mohamed A
    ScientificWorldJournal, 2015;2015:945689.
    PMID: 25759863 DOI: 10.1155/2015/945689
    Brain status information is captured by physiological electroencephalogram (EEG) signals, which are extensively used to study different brain activities. This study investigates the use of a new ensemble classifier to detect an epileptic seizure from compressed and noisy EEG signals. This noise-aware signal combination (NSC) ensemble classifier combines four classification models based on their individual performance. The main objective of the proposed classifier is to enhance the classification accuracy in the presence of noisy and incomplete information while preserving a reasonable amount of complexity. The experimental results show the effectiveness of the NSC technique, which yields higher accuracies of 90% for noiseless data compared with 85%, 85.9%, and 89.5% in other experiments. The accuracy for the proposed method is 80% when SNR=1 dB, 84% when SNR=5 dB, and 88% when SNR=10 dB, while the compression ratio (CR) is 85.35% for all of the datasets mentioned.
  5. Ali MS, Kamarudin SK, Masdar MS, Mohamed A
    ScientificWorldJournal, 2014;2014:103709.
    PMID: 25478581 DOI: 10.1155/2014/103709
    Power electronics and fuel cell technologies play an important role in the field of renewable energy. The demand for fuel cells will increase as fuel cells become the main power source for portable applications. In this application, a high-efficiency converter is an essential requirement and a key parameter of the overall system. This is because the size, cost, efficiency, and reliability of the overall system for portable applications primarily depend on the converter. Therefore, the selection of an appropriate converter topology is an important and fundamental aspect of designing a fuel cell system for portable applications as the converter alone plays a major role in determining the overall performance of the system. This paper presents a review of power electronics applications in fuel cell systems, which include various topology combinations of DC converters and AC inverters and which are primarily used in fuel cell systems for portable or stand-alone applications. This paper also reviews the switching techniques used in power conditioning for fuel cell systems. Finally, this paper addresses the current problem encountered with DC converters and AC inverter.
  6. Daud MZ, Mohamed A, Hannan MA
    ScientificWorldJournal, 2014;2014:271087.
    PMID: 24883374 DOI: 10.1155/2014/271087
    This paper presents an evaluation of an optimal DC bus voltage regulation strategy for grid-connected photovoltaic (PV) system with battery energy storage (BES). The BES is connected to the PV system DC bus using a DC/DC buck-boost converter. The converter facilitates the BES power charge/discharge to compensate for the DC bus voltage deviation during severe disturbance conditions. In this way, the regulation of DC bus voltage of the PV/BES system can be enhanced as compared to the conventional regulation that is solely based on the voltage-sourced converter (VSC). For the grid side VSC (G-VSC), two control methods, namely, the voltage-mode and current-mode controls, are applied. For control parameter optimization, the simplex optimization technique is applied for the G-VSC voltage- and current-mode controls, including the BES DC/DC buck-boost converter controllers. A new set of optimized parameters are obtained for each of the power converters for comparison purposes. The PSCAD/EMTDC-based simulation case studies are presented to evaluate the performance of the proposed optimized control scheme in comparison to the conventional methods.
  7. Sumathi S, Bhatia S, Lee KT, Mohamed AR
    J Hazard Mater, 2010 Apr 15;176(1-3):1093-6.
    PMID: 20018447 DOI: 10.1016/j.jhazmat.2009.11.037
    This work examines the impregnated carbon-based sorbents for simultaneous removal of SO(2) and NOx from simulated flue gas. The carbon-based sorbents were prepared using palm shell activated carbon (PSAC) impregnated with several metal oxides (Ni, V, Fe and Ce). The removal of SO(2) and NOx from the simulated flue gas was investigated in a fixed-bed reactor. The results showed that PSAC impregnated with CeO(2) (PSAC-Ce) reported the highest sorption capacity among other impregnated metal oxides for the simultaneous removal of SO(2) and NOx. PSAC-Ce showed the longest breakthrough time of 165 and 115 min for SO(2) and NOx, respectively. The properties of the pure and impregnated PSAC were analyzed by BET, FTIR and XRF. The physical-chemical features of the PSAC-Ce sorbent indicated a catalytic activity in both the sorption of SO(2) and NOx. The formation of both sulfate (SO(4)(2-)) and nitrate (NO(3-)) species on spent PSAC-Ce further prove the catalytic role played by CeO(2).
  8. Sumathi S, Bhatia S, Lee KT, Mohamed AR
    Bioresour Technol, 2009 Feb;100(4):1614-21.
    PMID: 18952414 DOI: 10.1016/j.biortech.2008.09.020
    Optimizing the production of microporous activated carbon from waste palm shell was done by applying experimental design methodology. The product, palm shell activated carbon was tested for removal of SO2 gas from flue gas. The activated carbon production was mathematically described as a function of parameters such as flow rate, activation time and activation temperature of carbonization. These parameters were modeled using response surface methodology. The experiments were carried out as a central composite design consisting of 32 experiments. Quadratic models were developed for surface area, total pore volume, and microporosity in term of micropore fraction. The models were used to obtain the optimum process condition for the production of microporous palm shell activated carbon useful for SO2 removal. The optimized palm shell activated carbon with surface area of 973 m(2)/g, total pore volume of 0.78 cc/g and micropore fraction of 70.5% showed an excellent agreement with the amount predicted by the statistical analysis. Palm shell activated carbon with higher surface area and microporosity fraction showed good adsorption affinity for SO2 removal.
  9. Saadiah S, Jeffrey AH, Mohamed AL
    Med J Malaysia, 1999 Jun;54(2):264-6.
    PMID: 10972040
    Penicillium marneffei, a dimorphic fungus is a rare opportunistic pathogen. It is known to cause infection in immunocompromised patients and recently its occurrence in AIDS patients has been well-documented. Disease with Penicillium marneffei is even rarer among previously healthy individuals. The disease is endemic in Southeast Asia and China. Recognition of this rare disease is important because it is amenable to treatment. We report a case of P. marneffei infection in a previously healthy individual.
  10. Selvaratnam G, Philips RH, Mohamed AK, Radzi A
    Adverse Drug React Toxicol Rev, 1997 Aug;16(3):171-97.
    PMID: 9512763
  11. Said H, Cheah F, Mohamed AS, Hadi AR
    Med J Malaysia, 1993 Jun;48(2):222-4.
    PMID: 8350800
    The transseptal transsphenoidal hypophysectomy has become a relatively frequent procedure in recent years. We performed 20 such procedures between January 1984 and December 1987 for various pituitary disorders. Significant complications such as CSF rhinorrhea, meningitis, diabetes insipidus, haemorrhage and septal perforation are discussed. The mortality rate for the series was 5%. In analysing the data, we feel that this technique of hypophysectomy is a safe procedure.
  12. Mohamed AK, Raja IA, Rukumani DV
    Med J Malaysia, 2020 05;75(3):199-203.
    PMID: 32467532
    INTRODUCTION: There are limited studies on the epidemiology of syphilis in Malaysia. In this study we describe the clinical features and treatment outcomes of patients with syphilis attending a tertiary referral university hospital.

    METHODS: We retrospectively reviewed the case records of patients with positive serology findings for syphilis in University Malaya Medical Center (UMMC) from January 2010 to December 2015. Serological positivity was defined as having a positive rapid plasma reagin (RPR) or Venereal Disease Research Laboratory (VDRL) with a confirmatory positive Treponema pallidum particle agglutination assay (TPPA). Treatment outcomes were divided into two, success or failure. Demographic and clinical characteristics associated with predictors of treatment failure were assessed using statistical package for the social science (SPSS). This study also included a neurosyphilis descriptive sub-study.

    RESULTS: There were 637 patients identified with positive syphilis serology, but 258 patients were excluded as they did not meet the inclusion criteria. 379 patients were then taken for the demographic study; 14 patients (3.7%) were treated for neurosyphilis; 170 patients with complete data were included. In all 42/170 (24.7%) failed treatment, 12/170 (7.1%) had reinfection and 116/170 (68.2%) had treatment success. A final number of 158 patients were then taken and analyzed for predictors of treatment failure after excluding the 12 reinfection patients. Only low baseline RPR (<1:16) was found to be significant on multivariate logistic regression analysis (p value: 0.007, 95% CI: 1.42, 9.21).

    CONCLUSION: Most of the patients were HIV positive and from the MSM (Men who have sex with Men) population. Low baseline RPR titre is a predictor of treatment failure.

  13. Looi PY, Mohamed AR, Tye CT
    J Nanosci Nanotechnol, 2013 Oct;13(10):6988-95.
    PMID: 24245175
    In this study, performances of mesoporous Mo/Al2O3 catalysts prepared by sol-gel and post-hydrolysis methods in hydrocracking of atmospheric residual oil were compared. In addition, different methods: (i) the single step and (ii) conventional impregnation method to incorporate active metal over the mesoporous support were also investigated. For single step method, Mo/Al2O3 catalysts were synthesized directly by sol-gel and post-hydrolysis method. On the other hand, the impregnation method was a two step procedure which involved the production of alumina via sol-gel or post-hydrolysis method and followed by respective Mo impregnation. In general, mesoporous Mo/Al2O3 catalysts prepared by sol-gel method resulted in relatively higher surface area (> 400 m2/g) and large pore volume (- 0.8 cm3/g). Mo/Al2O3 catalysts prepared by sol-gel method exhibited higher hydrocracking activity as well. The Mo crystal size was found to relate directly with the hydrocracking result.
  14. Pakeer O, Jeffery J, Mohamed AM, Ahmad F, Baharudin O
    Trop Biomed, 2007 Dec;24(2):101-3.
    PMID: 18209717 MyJurnal
    Four cases of pediculosis, two in adults and two in children, caused by the crab-louse, Pthirus pubis Linnaeus, 1758 (Diptera: Anoplura) is reported from peninsular Malaysia. This is the second report of the problem to be documented from the country. Although P. pubis is closely associated with genital hairs, it is, however, also found to occur on the eyelashes, eyebrows, hairs of the body, head and axilla. The few reported cases of pthiriasis probably do not reflect the true situation.
  15. Noha MA, Enas AE, Aly E, Mohamed AE
    Trop Biomed, 2019 Dec 01;36(4):833-844.
    PMID: 33597455
    BACKGROUND: Biomarkers by definition are measurable molecules that mark the evidence of certain pathological processes. Collaboration of various biomarkers influences morbidity of schsitosomiasis in Egypt.

    OBJECTIVES: To identify the biomarkers: CRP, IgE, hemoglobin, ferritin, vitamin D, and platelets in terms of relationship with active and chronic schistosomiasis; demographic data, and their interinfluence.

    STUDY DESIGN: A cross-sectional study.

    METHODS: Parasitological analysis of stool and urine samples, Indirect Hemagglutination Test, Enzyme linked Immunoassay, Hematology Analyzer, and Statistical Package SPSS (Statistical Package for the Social Sciences) version 25.

    RESULTS: Out of 400 participants, 25% suffered of schistosomiasis: active S. mansoni infections in 7 cases (1.75%), S. haematobium infections in 6 cases (1.5%), and chronic schistosomiasis infections in 20 cases (5%). Creactive protein (CRP) likewise IgE levels were higher in active S. mansoni and S. haematobium infections when compared with chronic schistosomiasis. IgE levels appeared to affect infection intensity in S. haematobium. Inversely, hemoglobin (Hb) values were low in active schistosomiasis and upgraded in chronic infection (*p<0.05). Ferritin levels varied in active Schistosoma infection and normalized during chronicity. Vitamin D was reduced in active and chronic schistosomiais. Platelet counts were within normal ranges throughout the study groups. Distribution of ferritin, vit D, and platelets was statistically insignificant among Schistosoma infected population. Age affected only hemoglobin, CRP, and IgE biomarkers. CRP and IgE were in direct relationship together and inversely proportional with hemoglobin (*P <0.05).

    CONCLUSION: Anemia increased proportionally with biomarkers of inflammatory stress (CRP and IgE) in early infections. Meanwhile, Hb and ferritin (iron stores) improved during chronicity. Hypovitaminosis-D associated the entire course of schistosomiasis while platelet counts were not affected.

  16. Aziz Mohamed, A., Hafizal Yazid, Sahrim Ahmad, Rozaidi Rasid, Jaafar Abdullah, Dahlan, M., et al.
    MyJurnal
    L18 orthogonal array in mix level of Taguchi robust design method was carried out to optimize experimental conditions for the preparation of polymer blend composite. Tensile strength and neutron absorption of the composite were the properties of interest. Filler size, filler loading, ball mixing time and dispersion agent concentration were selected as parameters or factors which are expected to affect the composite properties. As a result of Taguchi analysis, filler loading was the most influencing parameter on the tensile strength and neutron absorption. The least influencing was ball-mixing time. The optimal conditions were determined by using mix-level Taguchi robust design method and a polymer composite with tensile strength of 6.33 MPa was successfully prepared. The composite was found to fully absorb thermal neutron flux of 1.04 x 105n/cm2/s with only 2 mm in thickness. In addition, the filler was also characterized by scanning electron microscopy (SEM) and elemental analysis (EDX).
  17. Hafizal Yazid, Sahrim Ahmad, Aziz Mohamed, A., Dahlan, H.M., M. Rawi M. Z., Megat Harun, M.A., et al.
    MyJurnal
    The thermal conductivity of boron carbide filled thermoplastic natural rubber blend composite is studied experimentally as a function of filler loading and filler size. A polymer blend of 60/40 NR/HDPE was used as matrix for incorporation of particulate nano- and micro-sized B4C as filler to form the composite. As the filler loading is increased from 2-10%wt, a reduction and increment of thermal conductivity was observed. The results show at lower filler loading, HDPE crystallinity affects the thermal conductivity up to 4 and 6%wt of filler for nano- and micro-composite respectively. Further increase the loading do not much alter the crystallinity as the filler is distributed in continues phase of NR. The increment of filler amount in the amorphous NR causes the thermal conductivity to gradually increase which indicates the formation of interconnecting filler network structures
  18. Shareef H, Mutlag AH, Mohamed A
    Comput Intell Neurosci, 2017;2017:1673864.
    PMID: 28702051 DOI: 10.1155/2017/1673864
    Many maximum power point tracking (MPPT) algorithms have been developed in recent years to maximize the produced PV energy. These algorithms are not sufficiently robust because of fast-changing environmental conditions, efficiency, accuracy at steady-state value, and dynamics of the tracking algorithm. Thus, this paper proposes a new random forest (RF) model to improve MPPT performance. The RF model has the ability to capture the nonlinear association of patterns between predictors, such as irradiance and temperature, to determine accurate maximum power point. A RF-based tracker is designed for 25 SolarTIFSTF-120P6 PV modules, with the capacity of 3 kW peak using two high-speed sensors. For this purpose, a complete PV system is modeled using 300,000 data samples and simulated using the MATLAB/SIMULINK package. The proposed RF-based MPPT is then tested under actual environmental conditions for 24 days to validate the accuracy and dynamic response. The response of the RF-based MPPT model is also compared with that of the artificial neural network and adaptive neurofuzzy inference system algorithms for further validation. The results show that the proposed MPPT technique gives significant improvement compared with that of other techniques. In addition, the RF model passes the Bland-Altman test, with more than 95 percent acceptability.
  19. Sarker MR, Mohamed A, Mohamed R
    Micromachines (Basel), 2016 Sep 23;7(10).
    PMID: 30404344 DOI: 10.3390/mi7100171
    This paper presents a new method for a vibration-based piezoelectric energy harvesting system using a backtracking search algorithm (BSA)-based proportional-integral (PI) voltage controller. This technique eliminates the exhaustive conventional trial-and-error procedure for obtaining optimized parameter values of proportional gain (Kp), and integral gain (Ki) for PI voltage controllers. The generated estimate values of Kp and Ki are executed in the PI voltage controller that is developed through the BSA optimization technique. In this study, mean absolute error (MAE) is used as an objective function to minimize output error for a piezoelectric energy harvesting system (PEHS). The model for the PEHS is designed and analyzed using the BSA optimization technique. The BSA-based PI voltage controller of the PEHS produces a significant improvement in minimizing the output error of the converter and a robust, regulated pulse-width modulation (PWM) signal to convert a MOSFET switch, with the best response in terms of rise time and settling time under various load conditions.
Related Terms
Filters
Contact Us

Please provide feedback to Administrator ([email protected])

External Links