Displaying publications 21 - 34 of 34 in total

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  1. Bilal RMH, Saeed MA, Choudhury PK, Baqir MA, Kamal W, Ali MM, et al.
    Sci Rep, 2020 Aug 20;10(1):14035.
    PMID: 32820192 DOI: 10.1038/s41598-020-71032-8
    Achieving the broadband response of metamaterial absorbers has been quite challenging due to the inherent bandwidth limitations. Herein, the investigation was made of a unique kind of visible light metamaterial absorber comprising elliptical rings-shaped fractal metasurface using tungsten metal. It was found that the proposed absorber exhibits average absorption of over 90% in the visible wavelength span of 400-750 nm. The features of perfect absorption could be observed because of the localized surface plasmon resonance that causes impedance matching. Moreover, in the context of optoelectronic applications, the absorber yields absorbance up to ~ 70% even with the incidence obliquity in the range of 0°-60° for transverse electric polarization. The theory of multiple reflections was employed to further verify the performance of the absorber. The obtained theoretical results were found to be in close agreement with the simulation results. In order to optimize the results, the performance was analyzed in terms of the figure of merit and operating bandwidth. Significant amount of absorption in the entire visible span, wide-angle stability, and utilization of low-cost metal make the proposed absorber suitable in varieties of photonics applications, in particular photovoltaics, thermal emitters and sensors.
  2. Sa'don NA, Rahim AA, Ibrahim MNM, Brosse N, Hussin MH
    Int J Biol Macromol, 2017 Nov;104(Pt A):251-260.
    PMID: 28602987 DOI: 10.1016/j.ijbiomac.2017.06.038
    Lignin extracted from oil palm fronds (OPF) underwent chemical modification by incorporating m-cresol into the lignin matrix. This study reports on the physicochemical properties and antioxidant activity of unmodified autohydrolyzed ethanol organosolv lignin (AH EOL) and the modified autohydrolyzed ethanol organosolv lignin (AHC EOL). The lignin samples were analyzed by FTIR, 1H and 13C NMR spectroscopy, 2D NMR: HSQC spectroscopy, CHN analysis, molecular weight distribution analysis; GPC and thermal analysis; DSC and TGA. The lignin modification has reduced the hydrophobicity of its complex structure by providing better quality lignin with smaller fragments and higher solubility rate in water (DAHCEOL: 42%>DAHEOL: 25%). It was revealed that the modification of lignin has improved their structural and antioxidant properties, thus venture their possible applications.
  3. Koyama M, Nagao N, Syukri F, Rahim AA, Kamarudin MS, Toda T, et al.
    Bioresour Technol, 2018 Oct;265:207-213.
    PMID: 29902653 DOI: 10.1016/j.biortech.2018.05.109
    Development of thermophilic composting for maximizing NH3 gas recovery would enable the production of a nitrogen source which is free from pathogen/heavy metal, for the cultivation of high-value microalgae. The present study examined the effect of NH3 recovery, nitrogen mass balance, and microbial community dynamics on thermophilic composting of shrimp aquaculture sludge. The emission of NH3 gas at 60 and 70 °C was 14.7% and 15.6%, respectively, which was higher than that at 50 °C (9.0%). The nitrogen mass balance analysis revealed that higher temperatures enhanced the solubilization of non-dissolved nitrogen and liberation of NH3 gas from the produced NH4+-N. High-throughput microbial community analysis revealed the shift of the dominant bacterial group from Bacillus to Geobacillus with the rise of composting temperature. In conclusion, thermophilic composting of shrimp aquaculture sludge at 60-70 °C was the most favorable condition for enhancing NH3 gas recovery.
  4. Jajuli MN, Hussin MH, Saad B, Rahim AA, Hébrant M, Herzog G
    Anal Chem, 2019 06 04;91(11):7466-7473.
    PMID: 31050400 DOI: 10.1021/acs.analchem.9b01674
    A new sample preparation method is proposed for the extraction of pharmaceutical compounds (Metformin, Phenyl biguanide, and Phenformin) of varied hydrophilicity, dissolved in an aqueous sample. When in contact with an organic phase, an interfacial potential is imposed by the presence of an ion, tetramethylammonium (TMA+), common to each phase. The interfacial potential difference drives the transfer of ionic analytes across the interface and allows it to reach up to nearly 100% extraction efficiency and a 60-fold enrichment factor in optimized extraction conditions as determined by HPLC analysis.
  5. Abdul Rahim AA, Jeffree MS, Ag Daud DM, Pang N, Sazali MF
    Int J Environ Res Public Health, 2022 Sep 16;19(18).
    PMID: 36141974 DOI: 10.3390/ijerph191811704
    Musculoskeletal disorder (MSD) is a major health problem, which can lead to an enormous burden to the institution as well as chronic disability to the individual. Teachers are at risk of developing MSD due to the exposure to various ergonomic risk factors. Teachers of special education, for example, are expected to perform extra duty such as lifting and moving students, feeding food, changing diapers, and helping them in ambulation. Although there is an adequate amount of scientific research on MSD's prevalence and its risk factors among regular teachers, only few studies have focused on special education teachers. This review aimed to address these gaps by describing the evidence from various papers on the prevalence of MSD among regular and special education teachers and the related risk factors. The papers have been gathered using electronic databases, including PubMed, Science Direct, Google Scholar, and Springer. The prevalence of MSD among regular teachers ranges from 48.7% to 73.7%, while the prevalence ranges from 38.7% to 94% in special education teachers. Risk factors, such as individual (age, duration of teaching, working hours, and work burden), physical (teaching activities, affected body areas), and psychological factors (stress, anxiety, fear), were identified. From the review, it is recommended to implement ergonomically designed workplaces, comprehensive ergonomic training, psychological approaches, and functional training among teachers at risk.
  6. Yam H, Rahim AA, Mohamad S, Mahadi NM, Manaf UA, Shu-Chien AC, et al.
    PLoS One, 2014;9(6):e99218.
    PMID: 24927285 DOI: 10.1371/journal.pone.0099218
    Burkholderia pseudomallei is an opportunistic pathogen and the causative agent of melioidosis. It is able to adapt to harsh environments and can live intracellularly in its infected hosts. In this study, identification of transcriptional factors that associate with the β' subunit (RpoC) of RNA polymerase was performed. The N-terminal region of this subunit is known to trigger promoter melting when associated with a sigma factor. A pull-down assay using histidine-tagged B. pseudomallei RpoC N-terminal region as bait showed that a hypothetical protein BPSS1356 was one of the proteins bound. This hypothetical protein is conserved in all B. pseudomallei strains and present only in the Burkholderia genus. A BPSS1356 deletion mutant was generated to investigate its biological function. The mutant strain exhibited reduced biofilm formation and a lower cell density during the stationary phase of growth in LB medium. Electron microscopic analysis revealed that the ΔBPSS1356 mutant cells had a shrunken cytoplasm indicative of cell plasmolysis and a rougher surface when compared to the wild type. An RNA microarray result showed that a total of 63 genes were transcriptionally affected by the BPSS1356 deletion with fold change values of higher than 4. The expression of a group of genes encoding membrane located transporters was concurrently down-regulated in ΔBPSS1356 mutant. Amongst the affected genes, the putative ion transportation genes were the most severely suppressed. Deprivation of BPSS1356 also down-regulated the transcriptions of genes for the arginine deiminase system, glycerol metabolism, type III secretion system cluster 2, cytochrome bd oxidase and arsenic resistance. It is therefore obvious that BPSS1356 plays a multiple regulatory roles on many genes.
  7. Rahim AA, Lee YY, Majid NA, Choo KE, Raj SM, Derakhshan MH, et al.
    Am J Trop Med Hyg, 2010 Nov;83(5):1119-22.
    PMID: 21036849 DOI: 10.4269/ajtmh.2010.10-0226
    Whether the exceptionally low prevalence of Helicobacter pylori (HP) infection reported among Malays is also present among aborigines (the Orang Asli) living in northeastern Peninsular Malaysia is unknown. We studied asymptomatic Orang Asli from settlements situated 210 km from the city of Kota Bharu. The HP infection status was confirmed by a validated serology test. Nineteen percent of 480 Orang Asli tested positive for HP infection. The prevalence was 40.6% in the birth cohort of the 1940s and declined steadily in later cohorts to under 10% among 12-30 year olds. This may be related to the phases of relocation from the jungles into resettlement camps and ultimately into designated villages near rivers. The low prevalence pattern after the 1970s was probably partly a result of improvement in sanitation and hygiene practice in these villages but other unidentified factors may also be operating.
  8. Osman HA, Hasan H, Suppian R, Bahar N, Hussin NS, Rahim AA, et al.
    Asian Pac J Cancer Prev, 2014;15(13):5245-7.
    PMID: 25040982
    BACKGROUND: Helicobacter pylori (H. pylori) is one of the most important causes of dyspepsia and gastric cancer and diagnosis can be made by invasive or non-invasive methods. The Atlas Helicobacter pylori antigen test is a new rapid non-invasive method which is simple to conduct. The aim of this study was to determine its sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy.

    MATERIALS AND METHODS: This prospective study was conducted between July 2012 and December 2013. Stool samples of 59 dyspeptic patients who underwent upper endoscopy were evaluated for H. pylori stool antigen.

    RESULTS: From the 59 patients who participated in this study, there were 36 (61%) males and 23 (39%) females. H. pylori was diagnosed in 24 (40.7%) gastric biopsies, 22 (91.7 %) of these being positive for the Atlas H. pylori antigen test. The sensitivity, specificity, PPV, NPV and accuracy were 91.7%, 100%, 100%, 94.6% and 96.6% respectively.

    CONCLUSIONS: The Atlas H. pylori antigen test is a new non-invasive method which is simple to perform and avails reliable results in a few minutes. Thus it can be the best option for the diagnosis of H. pylori infection due to its high sensitivity and specificity.

  9. Hussin MH, Pohan NA, Garba ZN, Kassim MJ, Rahim AA, Brosse N, et al.
    Int J Biol Macromol, 2016 Jun 30;92:11-19.
    PMID: 27373428 DOI: 10.1016/j.ijbiomac.2016.06.094
    The present study sheds light on the physical and chemical characteristics of microcrystalline cellulose (MCC) isolated from oil palm fronds (OPF) pulps. It was found that the OPF MCC was identified as cellulose II polymorph, with higher crystallinity index than OPF α-cellulose (CrIOPFMCC: 71%>CrIOPFα-cellulose: 47%). This indicates that the acid hydrolysis allows the production of cellulose that is highly crystalline. BET surface area of OPF MCC was found to be higher than OPF α-cellulose (SBETOPFMCC: 5.64m(2)g(-1)>SBETOPFα-cellulose:Qa(0) 2.04m(2)g(-1)), which corroborates their potential as an adsorbent. In batch adsorption studies, it was observed that the experimental data fit well with Langmuir adsorption isotherm in comparison to Freundlich isotherm. The monolayer adsorption capacity (Qa(0)) of OPF MCC was found to be around 51.811mgg(-1) and the experimental data fitted well to pseudo-second-order kinetic model.
  10. Singh D, Narayanan S, Müller CP, Swogger MT, Rahim AA, Leong Bin Abdullah MFI, et al.
    J Psychoactive Drugs, 2018 08 28;50(5):445-450.
    PMID: 30152738 DOI: 10.1080/02791072.2018.1511879
    Kratom leaves (Mitragyna speciosa Korth.) are traditionally used in Southeast Asia for their medicinal value. Self-report studies suggest that cessation from chronic kratom tea consumption (freshly brewed kratom tea) was associated with unpleasant psychological symptoms. This study sought to assess the severity of anxiety and depression during kratom cessation. Regular kratom users (N = 150) were recruited from the northern state of Penang (Malaysia) for this retrospective study. The Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI) scales were used to assess the severity of the symptoms of anxiety and depression. Most respondents (70%) experienced symptoms of mild anxiety, while 81% experienced symptoms of mild depression during kratom cessation. Those who consumed higher quantities of kratom tea daily (≥4 glasses) had higher odds of reporting longer duration of kratom use history (OR = 4.8, 95% CI 2.3 -10.1, p 
  11. Oslan SNH, Shoparwe NF, Yusoff AH, Rahim AA, Chang CS, Tan JS, et al.
    Biomolecules, 2021 02 10;11(2).
    PMID: 33578851 DOI: 10.3390/biom11020256
    As the most recognizable natural secondary carotenoid astaxanthin producer, the green microalga Haematococcus pluvialis cultivation is performed via a two-stage process. The first is dedicated to biomass accumulation under growth-favoring conditions (green stage), and the second stage is for astaxanthin evolution under various stress conditions (red stage). This mini-review discusses the further improvement made on astaxanthin production by providing an overview of recent works on H. pluvialis, including the valuable ideas for bioprocess optimization on cell growth, and the current stress-exerting strategies for astaxanthin pigment production. The effects of nutrient constituents, especially nitrogen and carbon sources, and illumination intensity are emphasized during the green stage. On the other hand, the significance of the nitrogen depletion strategy and other exogenous factors comprising salinity, illumination, and temperature are considered for the astaxanthin inducement during the red stage. In short, any factor that interferes with the cellular processes that limit the growth or photosynthesis in the green stage could trigger the encystment process and astaxanthin formation during the red stage. This review provides an insight regarding the parameters involved in bioprocess optimization for high-value astaxanthin biosynthesis from H. pluvialis.
  12. Vicknasingam B, Chooi WT, Rahim AA, Ramachandram D, Singh D, Ramanathan S, et al.
    Yale J Biol Med, 2020 06;93(2):229-238.
    PMID: 32607084
    Background: Kratom has a long history of traditional medicine use in Southeast Asia. Consumption of kratom products has also been reported in the US and other regions of the world. Pain relief is among many self-reported kratom effects but have not been evaluated in controlled human subject research. Methods: Kratom effects on pain tolerance were assessed in a randomized, placebo-controlled, double-blind study. During a 1-day inpatient stay, participants received a randomized sequence of kratom and placebo decoctions matched for taste and appearance. Pain tolerance was measured objectively in a cold pressor task (CPT) as time (seconds) between the pain onset and the hand withdrawal from the ice bath. Health status, vital signs, objective, and subjective indicators of withdrawal symptoms, self-reported data on lifetime kratom use patterns, and assessments of blinding procedures were also evaluated. Results: Twenty-six males with the mean (SD) age 24.3 (3.4) years were enrolled. They reported the mean (SD) 6.1 (3.2) years of daily kratom consumption. Pain tolerance increased significantly 1 hour after kratom ingestion from the mean (SD) 11.2 (6.7) seconds immediately before to 24.9 (39.4) seconds 1 hour after kratom consumption (F(2,53.7)=4.33, p=0.02). Pain tolerance was unchanged after consuming placebo drinks: 15.0 (19.0) seconds immediately before and 12.0 (8.1) seconds 1 hour after consumption of placebo (F(2,52.8)=0.93, p=0.40). No discomfort or signs of withdrawal were reported or observed during 10-20 hours of kratom discontinuation. Conclusions: Kratom decoction demonstrated a substantial and statistically significant increase in pain tolerance. Further rigorous research on kratom pain-relieving properties and a safety profile is needed.
  13. Supramanian RK, Sivaratnam L, Rahim AA, Abidin NDIZ, Richai O, Zakiman Z, et al.
    PMID: 34540316 DOI: 10.5365/wpsar.2020.11.4.001
    BACKGROUND: COVID-19 was first detected in Malaysia on 25 January 2020. Multiple clusters were detected in Petaling District, with the first locally transmitted case reported on 8 February. Descriptive analyses of the epidemiology of the COVID-19 outbreak in Petaling are presented, from the first case to the end of the first wave.

    METHODS: All laboratory-confirmed COVID-19 cases reported to the Petaling District Health Office between 1 February and 26 June 2020 were analysed. Socio-demographic characteristics, symptoms, date of onset, date of exposure, travel history and history of comorbidities were obtained by phone interviews using one of two investigation forms. The descriptive analysis was conducted according to time, place and person.

    RESULTS: There were 437 COVID-19 cases, for an incidence rate of 24/100 000 population. Ten (2.3%) deaths and 427 recovered cases were recorded. Of the 437 cases, 35.5% remained asymptomatic and 64.5% were symptomatic. Common symptoms included fever (43.8%), cough (31.6%) and sore throat (16.2%); 67.3% had no comorbidities, 62.5% reported close contact with a confirmed case, and 76.7% were local infections. Transmission occurred in four main groups: religious gatherings (20.4%), corporations (15.1%), health facilities (10.3%) and a wholesale wet market (6.4%). In 31.9% of confirmed cases, an epidemiological link to an asymptomatic case was found.

    CONCLUSION: Transmission of the disease by asymptomatic cases should be emphasized to ensure continuous wearing of face masks, hand hygiene and social distancing. Further research should be conducted to better understand the transmission of SARS-CoV-2 from asymptomatic cases.

  14. Ang BH, Mariapun S, Farid FM, Ishak IS, Taib MFM, Rahim AA, et al.
    Cancer Causes Control, 2025 Feb 10.
    PMID: 39928248 DOI: 10.1007/s10552-025-01965-w
    PURPOSE: Urbanization has emerged as one of the main determinants of the rising breast cancer incidence in Asia, but understanding the link is hindered by the lack of population-based prospective cohorts, especially in low- and middle-income countries. Given that mammographic density (MD) is one of the strongest breast cancer risk factors and that it is associated with known lifestyle and reproductive factors, we explored using MD to delineate factors associated with differences in breast cancer risk between women living in urban and rural areas.

    METHODS: Using data from a cross-sectional study of 9,417 women living in urban or rural areas recruited through hospital- or community-based opportunistic mammography screening programs, we conducted regression and mediation analyses to identify factors contributing to the differences in MD between urban and rural populations across Asian ethnic subgroups.

    RESULTS: Consistent with higher risk of breast cancer, age-and-BMI-adjusted percent and absolute MD measurements were significantly higher in women living in urban areas compared to those in rural areas. Mediation analyses showed that differences observed were partly explained by higher parity (7-9%) and breastfeeding (2-3%) among women living in rural areas. Notably, the effect of parity (number of children) was similar in Chinese and Malay women (16-17% and 7-8%, respectively), but not observed in Indian women. Hormonal use, smoking, and physical activity did not predict MD nor mediate the observed association.

    CONCLUSION: Higher MD among women living in urban compared to rural areas is partially attributable to parity and breastfeeding practices, a significant proportion of attributable risk remains unknown.

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