Displaying publications 1 - 20 of 43 in total

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  1. Chuan MW, Wong KL, Riyadi MA, Hamzah A, Rusli S, Alias NE, et al.
    PLoS One, 2021;16(6):e0253289.
    PMID: 34125874 DOI: 10.1371/journal.pone.0253289
    Silicene has attracted remarkable attention in the semiconductor research community due to its silicon (Si) nature. It is predicted as one of the most promising candidates for the next generation nanoelectronic devices. In this paper, an efficient non-iterative technique is employed to create the SPICE models for p-type and n-type uniformly doped silicene field-effect transistors (FETs). The current-voltage characteristics show that the proposed silicene FET models exhibit high on-to-off current ratio under ballistic transport. In order to obtain practical digital logic timing diagrams, a parasitic load capacitance, which is dependent on the interconnect length, is attached at the output terminal of the logic circuits. Furthermore, the key circuit performance metrics, including the propagation delay, average power, power-delay product and energy-delay product of the proposed silicene-based logic gates are extracted and benchmarked with published results. The effects of the interconnect length to the propagation delay and average power are also investigated. The results of this work further envisage the uniformly doped silicene as a promising candidate for future nanoelectronic applications.
  2. Purwanti IF, Abdullah SRS, Hamzah A, Idris M, Basri H, Latif MT, et al.
    Heliyon, 2023 Nov;9(11):e21737.
    PMID: 38027659 DOI: 10.1016/j.heliyon.2023.e21737
    Phytoremediation is one of the green technologies that is friendly to nature, utilizes fewer chemicals, and exhibits good performance. In this study, phytoremediation was used to treat diesel-contaminated sand using a local aquatic plant species, Scirpus mucronatus, by analyzing the amount of total petroleum hydrocarbons (TPHs). Optimization of diesel removal was performed according to Response Surface Methodology (RSM) using Box-Behnken Design (BBD) under pilot-scale conditions. The quadratic model showed the best fit to describe the obtained data. Actual vs. predicted values from BBD showed a total of 9.1 % error for the concentration of TPH in sand and 0 % error for the concentration of TPH in plants. Maximum TPH removal of 42.3 ± 2.1 % was obtained under optimized conditions at a diesel initial concentration of 50 mg/kg, an aeration rate of 0.48 L/min, and a retention time of 72 days. The addition of two species of rhizobacteria (Bacillus subtilis and Bacillus licheniformis) at optimum conditions increased the TPH removal to 51.9 ± 2.6 %. The obtained model and optimum condition can be adopted to treat diesel-contaminated sand within the same TPH range (50-3000 mg/kg) in sand.
  3. Hamzah A, Krauss SE, Shaffril HA, Suandi T, Ismail IA, Abu Samah B
    Int J Psychol, 2014 Oct;49(5):397-403.
    PMID: 25178962 DOI: 10.1002/ijop.12010
    The vast majority of Malaysia's fishermen are located in rural areas, specifically in the Western and Eastern coastal regions of Peninsular Malaysia and the Sabah and Sarawak central zones. In these areas, the fishing industry is relied upon as a major economic contributor to the region's residents. Despite the widespread application of various modern technologies into the fishing industry (i.e., GPS, sonar, echo sounder, remote sensing), and the Malaysian government's efforts to encourage their adoption, many small-scale fishermen in the country's rural areas continue to rely on traditional fishing methods. This refusal to embrace new technologies has resulted in significant losses in fish yields and needed income, and has raised many questions regarding the inputs to decision making of the fishermen. Drawing on multiple literatures, in this article we argue for the use of a mental model approach to gain an in-depth understanding of rural Malaysian fishermen's choices of technology adoption according to four main constructs--prior experience, knowledge, expertise and beliefs or values. To provide needed inputs to agricultural specialists and related policy makers for the development of relevant plans of action, this article aims to provide a way forward for others to understand dispositional barriers to technology adoption among fishermen who use traditional methods in non-Western contexts.
  4. Bahraminejad N, Ibrahim F, Riji HM, Majdzadeh R, Hamzah A, Keshavarz Mohammadi N
    Health Promot Int, 2015 Dec;30(4):963-75.
    PMID: 24934454 DOI: 10.1093/heapro/dau043
    Community-based health promotion requires effective participation and partnership of diverse and numerous stakeholders from community as well as external professional organizations. Although effective partnership of stakeholders is often the key for success of health promotion practice and research, but this has proved to be a complex and challenging task. This study is an exploratory study to identify professional stakeholder's perspectives and experiences toward the partner's engagement challenges in community-based participatory research conducted in Population Research Centers in Iran. A qualitative study design with in-depth semi-structured interviews as data collection method was chosen. Using purposeful sampling technique, policy-makers and managers (mainly academics) involved in community-based participatory research in these centers were invited to be interviewed. Data were collected to the point where no new information was forthcoming. All interviews were taped and transcribed. To provide answers for research questions, qualitative content analysis was employed to extract emerging main themes from numerous cods. Findings were categorized in three main themes as Partnership's relationship and trust issues, Partnership's individual issues and Partnership's system issues. Although community-based participatory research in Iran benefits from more than a decade history and some physical infrastructures, but it seems that public health experts and researchers and other partner organizations are lagging behind in terms of capacities and competencies required to effectively utilize the available structure and opportunities. Hence, capacity development, both among professional partners and community may be the main way forward to tackling the future challenges for strengthening community actions but should include both levels of individuals and systems.
  5. Wibowo A, Ahmat N, Hamzah AS, Low AL, Mohamad SA, Khong HY, et al.
    Fitoterapia, 2012 Dec;83(8):1569-75.
    PMID: 22982329 DOI: 10.1016/j.fitote.2012.09.004
    A new oligostilbenoid tetramer, malaysianol B (1), was isolated from the acetone extract of the stem bark of Dryobalanops lanceolata along with seven oligostilbenoids tetramers; hopeaphenol (2), stenophyllol A (3), nepalensinol B (4), vaticanol B (5) and C (6), upunaphenol D (7), and flexuosol A (8). The structures of the isolated compounds were established on the basis of their spectroscopic data evidence. The antibacterial activity of the isolated compounds was evaluated using resazurin microtitre-plate assay.
  6. Wibowo A, Ahmat N, Hamzah AS, Sufian AS, Ismail NH, Ahmad R, et al.
    Fitoterapia, 2011 Jun;82(4):676-81.
    PMID: 21338657 DOI: 10.1016/j.fitote.2011.02.006
    A new resveratrol trimer, malaysianol A (1), five known resveratrol oligomers: laevifonol (2), ampelopsin E (3), α-viniferin (4), ε-viniferin (5), diptoindonesin A (6), and bergenin (7) have been isolated from the acetone extract of the stem bark of Dryobalanops aromatica by combination of vacuum and radial chromatography techniques. Their structures were established on the basis of their spectroscopic evidence and comparison with the published data. The cytotoxic activity of the compounds was tested against several cell lines in which compound 4 was found to inhibit strongly the growth of HL-60 cell line.
  7. Idris K, Mohamed Shaffril HA, Md Yassin S, Abu Samah A, Hamzah A, Abu Samah B
    PLoS One, 2016;11(3):e0150741.
    PMID: 26974837 DOI: 10.1371/journal.pone.0150741
    The main aim of this study is to identify the quality of life (QoL) among communities residing near the Tembeling, Pahang and Muar Rivers in Malaysia. This quantitative study used a constructed questionnaire as main tool to collect data on the QoL of river communities. A total of 240 villagers were selected as respondents. The results indicated that the dimensions of settlement, safety, involvement and social relationships, as well as education scored highest, while dimensions of physical environment, financial and job security yielded moderate scores. Dimensions of infrastructure facilities yielded a low mean score. Recommendations are provided, in the hope that our results may be useful for strategies that could enhance QoL of these river communities.
  8. Saha K, Lajis NH, Israf DA, Hamzah AS, Khozirah S, Khamis S, et al.
    J Ethnopharmacol, 2004 Jun;92(2-3):263-7.
    PMID: 15138010
    Methanol extracts of seven Malaysian medicinal plants were screened for antioxidant and nitric oxide inhibitory activities. Antioxidant activity was measured by using FTC, TBA and DPPH free radical scavenging methods and Griess assay was used for the measurement of nitric oxide inhibition in lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma)-treated RAW 264.7 cells. All the extracts showed strong antioxidant activity comparable to or higher than that of alpha-tocopherol, BHT and quercetin in FTC and TBA methods. The extracts from Leea indica and Spermacoce articularis showed strong DPPH free radical scavenging activity comparable with quercetin, BHT and Vit C. Spermacoce exilis showed only moderate activity but other species were weak as compared to the standards. In the Griess assay Lasianthus oblongus, Chasalia chartacea, Hedyotis verticillata, Spermacoce articularis and Leea indica showed strong inhibitory activity on nitric oxide production in LPS and IFN-gamma-induced RAW 264.7 cells. Extracts from Psychotria rostrata and Spermacoce exilis also inhibited NO production but this was due to their cytotoxic effects upon cells during culture.
  9. Sim SK, Lau BL, Zaila SR, Hazira N, Aniqah NM, Panicker J, et al.
    Med J Malaysia, 2021 03;76(2):138-144.
    PMID: 33742619
    INTRODUCTION: Healthcare workers serve as the frontliners against the coronavirus 2019 disease (COVID-19) and this puts them most at risk of infection as they attend to numerous patients with unknown status. This study aimed to examine stress, anxiety, and depression among healthcare workers caring for COVID-19 patients in Sarawak General Hospital (SGH), Malaysia.

    MATERIALS AND METHODS: This cross-sectional observational study conducted in SGH during the pandemic with an online self-administered questionnaire composed of two parts, the socio-demographic characteristics, and the Depression Anxiety Stress Scale (DASS).

    RESULTS: A total of 105 healthcare workers responded to this study. A questionnaire in both Bahasa Melayu and English was used. The findings showed that all healthcare workers had mild anxiety, with the majority experiencing mild stress (57.1%), and almost half of the respondents experiencing mild depression (41%). Female subjects had a significant higher mean score in anxiety level and stress level compared to male subjects (10.0±3.20 vs. 8.6±2.93, p<0.05; 14.1±4.76 vs. 10.7±3.70, p<0.05, respectively). Staff who were transferred from other units to handle COVID-19 cases experienced more psychological symptoms. There were significant correlations between the depression, anxiety and stress levels among the healthcare workers and the number of children they had (r=0.739, p=0.001; r=0.642, p=0.001; r=1, p =0.001 respectively). However, the stress level among the healthcare workers was reversely correlated with their years of working experience (r=-0.199, p=0.042).

    CONCLUSION: This study identified some socio-demographic factors associated with increased levels of stress, anxiety and depression among the healthcare workers during pandemic, which may lay ground for future interventions.

  10. Hosseingholipourasl A, Hafizah Syed Ariffin S, Ahmadi MT, Rahimian Koloor SS, Petrů M, Hamzah A
    Sensors (Basel), 2020 Jan 08;20(2).
    PMID: 31936402 DOI: 10.3390/s20020357
    Recent advances in nanotechnology have revealed the superiority of nanocarbon species such as carbon nanotubes over other conventional materials for gas sensing applications. In this work, analytical modeling of the semiconducting zigzag carbon nanotube field-effect transistor (ZCNT-FET) based sensor for the detection of gas molecules is demonstrated. We propose new analytical models to strongly simulate and investigate the physical and electrical behavior of the ZCNT sensor in the presence of various gas molecules (CO2, H2O, and CH4). Therefore, we start with the modeling of the energy band structure by acquiring the new energy dispersion relation for the ZCNT and introducing the gas adsorption effects to the band structure model. Then, the electrical conductance of the ZCNT is modeled and formulated while the gas adsorption effect is considered in the conductance model. The band structure analysis indicates that, the semiconducting ZCNT experiences band gap variation after the adsorption of the gases. Furthermore, the bandgap variation influences the conductance of the ZCNT and the results exhibit increments of the ZCNT conductance in the presence of target gases while the minimum conductance shifted upward around the neutrality point. Besides, the I-V characteristics of the sensor are extracted from the conductance model and its variations after adsorption of different gas molecules are monitored and investigated. To verify the accuracy of the proposed models, the conductance model is compared with previous experimental and modeling data and a good consensus is observed. It can be concluded that the proposed analytical models can successfully be applied to predict sensor behavior against different gas molecules.
  11. Taib AK, Johari Z, Abd Rahman SF, Mohd Yusoff MF, Hamzah A
    PLoS One, 2023;18(3):e0282370.
    PMID: 36897883 DOI: 10.1371/journal.pone.0282370
    In this study, computational simulations were used to investigate the performance of a carbon-doped boron nitride nanoribbon (BC2NNR) for hydrogen (H2) gas sensing at elevated temperatures. The adsorption energy and charge transfer were calculated when H2 was simultaneously attached to carbon, boron, and both boron and nitrogen atoms. The sensing ability was further analyzed considering the variations in current-voltage (I-V) characteristics. The simulation results indicated that the energy bandgap of H2 on carbon, boron, and both boron and nitrogen exhibited a marginal effect during temperature variations. However, significant differences were observed in terms of adsorption energy at a temperature of 500 K, wherein the adsorption energy was increased by 99.62% of that observed at 298 K. Additionally, the evaluation of charge transfer indicated that the strongest binding site was achieved at high adsorption energies with high charge transfers. Analysis of the I-V characteristics verified that the currents were considerably affected, particularly when a certain concentration of H2 molecules was added at the highest sensitivity of 15.02% with a bias voltage of 3 V. The sensitivity at 298 K was lower than those observed at 500 and 1000 K. The study findings can form the basis for further experimental investigations on BC2NNR as a hydrogen sensor.
  12. Chuan MW, Riyadi MA, Hamzah A, Alias NE, Mohamed Sultan S, Lim CS, et al.
    PLoS One, 2022;17(3):e0264483.
    PMID: 35239699 DOI: 10.1371/journal.pone.0264483
    Moore's Law is approaching its end as transistors are scaled down to tens or few atoms per device, researchers are actively seeking for alternative approaches to leverage more-than-Moore nanoelectronics. Substituting the channel material of a field-effect transistors (FET) with silicene is foreseen as a viable approach for future transistor applications. In this study, we proposed a SPICE-compatible model for p-type (Aluminium) uniformly doped silicene FET for digital switching applications. The performance of the proposed device is benchmarked with various low-dimensional FETs in terms of their on-to-off current ratio, subthreshold swing and drain-induced barrier lowering. The results show that the proposed p-type silicene FET is comparable to most of the selected low-dimensional FET models. With its decent performance, the proposed SPICE-compatible model should be extended to the circuit-level simulation and beyond in future work.
  13. Jada SR, Matthews C, Saad MS, Hamzah AS, Lajis NH, Stevens MF, et al.
    Br J Pharmacol, 2008 Nov;155(5):641-54.
    PMID: 18806812 DOI: 10.1038/bjp.2008.368
    BACKGROUND AND PURPOSE: Andrographolide, the major phytoconstituent of Andrographis paniculata, was previously shown by us to have activity against breast cancer. This led to synthesis of new andrographolide analogues to find compounds with better activity than the parent compound. Selected benzylidene derivatives were investigated for their mechanisms of action by studying their effects on the cell cycle progression and cell death.
    EXPERIMENTAL APPROACH: Microculture tetrazolium, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and sulphorhodamine B (SRB) assays were utilized in assessing the in vitro growth inhibition and cytotoxicity of compounds. Flow cytometry was used to analyse the cell cycle distribution of control and treated cells. CDK1 and CDK4 levels were determined by western blotting. Apoptotic cell death was assessed by fluorescence microscopy and flow cytometry.
    KEY RESULTS: Compounds, in nanomolar to micromolar concentrations, exhibited growth inhibition and cytotoxicity in MCF-7 (breast) and HCT-116 (colon) cancer cells. In the NCI screen, 3,19-(2-bromobenzylidene) andrographolide (SRJ09) and 3,19-(3-chloro-4-fluorobenzylidene) andrographolide (SRJ23) showed greater cytotoxic potency and selectivity than andrographolide. SRJ09 and SRJ23 induced G(1) arrest and apoptosis in MCF-7 and HCT-116 cells, respectively. SRJ09 downregulated CDK4 but not CDK1 level in MCF-7 cells. Apoptosis induced by SRJ09 and SRJ23 in HCT-116 cells was confirmed by annexin V-FITC/PI flow cytometry analysis.
    CONCLUSION AND IMPLICATIONS: The new benzylidene derivatives of andrographolide are potential anticancer agents. SRJ09 emerged as the lead compound in this study, exhibiting anticancer activity by downregulating CDK4 to promote a G(1) phase cell cycle arrest, coupled with induction of apoptosis.
  14. Xian TK, Omar NA, Ying LW, Hamzah A, Raj S, Jaarin K, et al.
    PMID: 23320039 DOI: 10.1155/2012/828170
    Background. Palm oil is commonly consumed in Asia. Repeatedly heating the oil is very common during food processing. Aim. This study is aimed to report on the risk of atherosclerosis due to the reheated oil consumption. Material and Methods. Twenty four male Sprague Dawley rats were divided into control, fresh-oil, 5 times heated-oil and 10 times heated-oil feeding groups. Heated palm oil was prepared by frying sweet potato at 180°C for 10 minutes. The ground standard rat chows were fortified with the heated oils and fed it to the rats for six months. Results. Tunica intima thickness in aorta was significantly increased in 10 times heated-oil feeding group (P < 0.05), revealing a huge atherosclerotic plaque with central necrosis projecting into the vessel lumen. Repeatedly heated oil feeding groups also revealed atherosclerotic changes including mononuclear cells infiltration, thickened subendothelial layer, disrupted internal elastic lamina and smooth muscle cells fragmentation in tunica media of the aorta. Conclusion. The usage of repeated heated oil is the predisposing factor of atherosclerosis leading to cardiovascular diseases. It is advisable to avoid the consumption of repeatedly heated palm oil.
  15. Hamzah SR, Suandi T, Krauss SE, Hamzah A, Tamam E
    Int J Adolesc Youth, 2014 Oct 2;19(4):419-433.
    PMID: 25431513
    This study was carried out on the moderating effect of peer attachment on the relationships between religiosity and worldview, and on how hedonistic behaviour among Malaysian undergraduate students is shaped by such influences. With regard to peer attachment, the study focused on the influences of communication, trust and alienation among youth. Bronfenbrenner's theory of human ecology and Armsden and Greenberg's attachment model were used as the framework. Drawing on a quantitative survey of 394 Malaysian university students (M age = 21.0, SD = 0.40), structural equation modelling and path analysis revealed a significant relationship between worldview and hedonistic behaviour. Peer attachment moderated the relationships between religiosity and religious worldview. The results further showed that the unique moderating effect of the lower level of attachment with peers is positively related to the hedonistic behaviour. Implications from the findings are discussed.
  16. Amir Hamzah AR, Tiow CA, Koh GT, Sharifah AM
    Med J Malaysia, 2011 Mar;66(1):19-21.
    PMID: 23765137
    Transcatheter closure of small and moderate sizes of Patent Ductus Arteriosus (PDA) is a standard and well accepted form of treatment. The aim of this study is to describe the experience of transcatheter closure of PDA in Penang Hospital. All patients who underwent transcatheter closure of PDA at our institution between 20th January 2006 and 27th June 2008 were retrospectively identified and studied. There were a total of 66 patients who had undergone transcatheter closure of PDA during this period which comprised of 24 male and 42 female. The PDA was closed by Amplatzer Duct Occluder (ADO) in 31 patients, Gianturco coil in 29 patients and other types of devices in 6 patients. There were 4 patients (6%) who had developed acute complication during the procedure (3 of them developed coil embolization and 1 had bleeding from puncture site). The PDA was successfully close in 95.5% of the study population without any residual PDA shunting. All the patients were alive but 5 of them (4.5%) have some abnormalities (2 has mild left pulmonary stenosis, 3 has small residual). Comparison between ADO and Gianturco coil revealed no significant difference in the outcome. Transcatheter closure of PDA has proven to be safe and effective with good midterm outcome. There was no significant difference between Amplatzer Ductal Occluder and Gianturco coil in term of the outcome.
  17. Koh GT, Ai Mokthar S, Hamzah A, Kaur J
    Ann Pediatr Cardiol, 2009 Jul;2(2):159-61.
    PMID: 20808631 DOI: 10.4103/0974-2069.58320
    We report a case of transcatheter closure of patent ductus arteriosus using the new Amplatzer duct occluder II in an adult patient with interrupted inferior vena cava with azygous continuation via the femoral artery approach.
  18. Asadi-Shekari Z, Moeinaddini M, Sultan Z, Shah MZ, Hamzah A
    Traffic Inj Prev, 2016 08 17;17(6):650-5.
    PMID: 26890058 DOI: 10.1080/15389588.2015.1136739
    OBJECTIVE: A number of efforts have been conducted on travel behavior and transport fatalities at the neighborhood or street level, and they have identified different factors such as roadway characteristics, personal indicators, and design indicators related to transport safety. However, only a limited number of studies have considered the relationship between travel behavior indicators and the number of transport fatalities at the city level. Therefore, this study explores this relationship and how to fill the mentioned gap in current knowledge.

    METHOD: A generalized linear model (GLM) estimates the relationships between different travel mode indicators (e.g., length of motorway per inhabitants, number of motorcycles per inhabitant, percentage of daily trips on foot and by bicycle, percentage of daily trips by public transport) and the number of passenger transport fatalities. Because this city-level model is developed using data sets from different cities all over the world, the impacts of gross domestic product (GDP) are also included in the model.

    CONCLUSIONS: Overall, the results imply that the percentage of daily trips by public transport, the percentage of daily trips on foot and by bicycle, and the GDP per inhabitant have negative relationships with the number of passenger transport fatalities, whereas motorway length and the number of motorcycles have positive relationships with the number of passenger transport fatalities.

  19. Quah BS, Mazidah AR, Hamzah AM, Simpson H
    Asian Pac J Allergy Immunol, 2000 Mar;18(1):15-21.
    PMID: 12546053
    While many studies of the prevalence of wheeze have been conducted in schoolchildren, there have been few in pre-school children. Most children with asthma develop symptoms before the age of 5 years and many pre-school wheezers continue to wheeze in the early school years. Among the latter, those children who continue to wheeze at school age have poorer lung function than those who don't. It is thus appropriate to enquire more fully about wheeze in this age-group where its incidence is high and its relation with asthma less well defined. The objective of this study was to investigate the prevalences of wheeze, night cough and doctor diagnosed asthma in pre-school children. A cross-sectional study was conducted in five primary health clinics in the district of Kota Bharu from April to October 1998. Nurses from these clinics distributed Bahasa Malaysia questionnaires containing questions on asthma symptoms to preschool children aged 1-5 years during their home visits. The respondents were parent(s) or carer(s) of the child. The response rate was 100% and a total of 2,878 responses were analysed. The prevalence of symptoms and doctor diagnosed asthma were as follows: ever wheezed 9.4% (95% confidence interval (CI) 8.3-10.4%); current wheeze 6.2% (95% CI 5.2 to 7.0%); night cough 10.2% (95% CI 9.1 to 11.4%); and doctor diagnosed asthma 7.1% (95% CI 6.2 to 8.0%). There were no significant differences in prevalence between males and females, or among age groups. The prevalence of night cough in children with no history of wheeze was 6.9%. The cumulative and current prevalences of wheeze were similar to, and those of night cough and doctor-diagnosed asthma significantly lower than, those reported for Kelantan schoolchildren. These findings provide a baseline for assessing future symptoms trends, and perhaps also the validity of diagnosing asthma in this age group.
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