Displaying publications 1 - 20 of 44 in total

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  1. Abu Bakar SA, Nadarajah S, Absl Kamarul Adzhar ZA, Mohamed I
    PLoS One, 2016;11(6):e0156537.
    PMID: 27272043 DOI: 10.1371/journal.pone.0156537
    In this paper, we introduce the R package gendist that computes the probability density function, the cumulative distribution function, the quantile function and generates random values for several generated probability distribution models including the mixture model, the composite model, the folded model, the skewed symmetric model and the arc tan model. These models are extensively used in the literature and the R functions provided here are flexible enough to accommodate various univariate distributions found in other R packages. We also show its applications in graphing, estimation, simulation and risk measurements.
  2. Abu Bakar SA, Muda SM, Mohd Arifin SR, Ishak S
    Enferm Clin, 2019 09;29 Suppl 2:725-732.
    PMID: 31337573 DOI: 10.1016/j.enfcli.2019.06.012
    OBJECTIVE: To identify the existing literature on mothers' perception towards the impact of expressing breast milk for their premature infant in the neonatal intensive care unit.

    METHOD: Guided by the PRISMA Statement review checklist, a systematic review of the Scopus and Web of Science database has identified 10 related studies. The articles were assessed and analyzed after evaluated using The Joanna Briggs Institute Critical Appraisal tools (JBI). Thematic analysis was obtained after using Nvivo software as a tool for data analysis by author.

    RESULT: Further review of these articles resulted in three main themes-maternal changes during expressing breast milk, pumping challenges and impact of motivation factors to initiating lactation.

    CONCLUSION: Expressing breast milk should be recognized as an important way to restructure motherhood with a preterm infant in NICU. However, maintaining expressed breast milk during preterm infants' treatment period in NICU may increase stress and difficulties for some mothers. Some recommendations are emphasized in relation to the need for more qualitative studies in this issue, which is to have a specific and standard systematic review method for guide research synthesis in context of climate change adaptation.

  3. Abu Bakar SA, Syed Mohamed Shahruddin SNS, Ismail N, Wan Md Adnan WAH
    PeerJ, 2022;10:e13694.
    PMID: 35935256 DOI: 10.7717/peerj.13694
    The estimation of biological age (BA) is an important asymptomatic measure that can be used to understand the physical changes and the aging process of a living being. Factors that contribute towards profiling the human biological age can be diverse. Therefore, this study focuses on developing a BA model for patients with Chronic Kidney Disease (CKD). The procedure commences with the selection of significant biomarkers using a correlation test. Appropriate weighting is then assigned to each selected biomarker using the indexing method to produce a BA index. The BA index is matched to the age variation within the sample to acquire additional terms for the chronological age leading ultimately to the estimated BA. From a sample of 190 patients (133 trained data and 57 testing data) obtained from the University of Malaya Medical Centre (UMMC), Malaysia, the intensity of the BA is found to be between three to nine years from the chronological age. Visual observations further validate the high similarities between the training and testing data sets.
  4. Ahmad F, Bakar SA, Ibrahim AZ, Read RW
    Planta Med, 1997 Apr;63(2):193-4.
    PMID: 17252347
  5. Ahmed S, Shahid MM, Bakar SA, Arshed N, Basirun WJ, Fouad H
    J Nanosci Nanotechnol, 2020 12 01;20(12):7705-7709.
    PMID: 32711646 DOI: 10.1166/jnn.2020.18570
    Herein, we report the synthesis of SnO, Cu₂O and SnO-Cu₂O mixed oxide thin films on fluorinedoped tin oxide (FTO) substrate by Aerosol-Assisted Chemical Vapour Deposition (AACVD) process using [Cu (dmae)₂(H₂O)] and [Sn (dmae) (OAc)]₂ as molecular precursors for SnO and Cu₂O, respectively at 400 °C. The X-ray diffraction (XRD) pattern can be ascribed to the tetragonal phase of SnO crystals with space group P4 and cubic phase of Cu₂O crystals with space group Pn- 3m/nmm, respectively. The surface morphology characteristics of SnO, Cu₂O and SnO-Cu₂Omixed oxide have been investigated using Field Emission Scanning Electron Microscope (FESEM) which revealed that the SnO was grown homogeneously in cubical shape while Cu₂O possess nano balls shaped morphologies. The UV band gap values of SnO-Cu₂O mixed oxide thin film was found to be 2.6 eV appropriate for photoelectrochemical (PEC) applications. The synthesized material was proposed for PEC applications and has shown enhanced catalytic performance in the presence of light.
  6. Alabsi AM, Bakar SA, Ali R, Omar AR, Bejo MH, Ideris A, et al.
    Int J Mol Sci, 2011;12(12):8645-60.
    PMID: 22272097 DOI: 10.3390/ijms12128645
    Newcastle disease virus (NDV) is used as an antineoplastic agent in clinical tumor therapy. It has prompted much interest as an anticancer agent because it can replicate up to 10,000 times better in human cancer cells than in most normal cells. This study was carried out to determine the oncolytic potential of NDV strain AF2240 and V4-UPM on WEHI-3B leukemia cell line. Results from MTT cytotoxicity assay showed that the CD(50) values for both strains were 2 and 8 HAU for AF2240 and V4-UPM, respectively. In addition, bromodeoxyuridine (BrdU) and trypan blue dye exclusion assays showed inhibition in cell proliferation after different periods. Increase in the cellular level of caspase-3 and detection of DNA laddering using agarose gel electrophoresis on treated cells with NDV confirmed that the mode of cell death was apoptosis. In addition, flow-cytometry analysis of cellular DNA content showed that the virus caused an increase in the sub-G1 region (apoptosis peaks). In conclusion, NDV strains AF2240 and V4-UPM caused cytolytic effects against WEHI-3B leukemic cell line.
  7. Algaifi HA, Mustafa Mohamed A, Alsuhaibani E, Shahidan S, Alrshoudi F, Huseien GF, et al.
    Polymers (Basel), 2021 Aug 16;13(16).
    PMID: 34451289 DOI: 10.3390/polym13162750
    Although free-cement-based alkali-activated paste, mortar, and concrete have been recognised as sustainable and environmental-friendly materials, a considerable amount of effort is still being channeled to ascertain the best binary or ternary binders that would satisfy the requirements of strength and durability as well as environmental aspects. In this study, the mechanical properties of alkali-activated mortar (AAM) made with binary binders, involving fly ash (FA) and granulated blast-furnace slag (GBFS) as well as bottle glass waste nano-silica powder (BGWNP), were opti-mised using both experimentally and optimisation modelling through three scenarios. In the first scenario, the addition of BGWNP varied from 5% to 20%, while FA and GBFS were kept constant (30:70). In the second and third scenarios, BGWNP (5-20%) was added as the partial replacement of FA and GBFS, separately. The results show that the combination of binary binders (FA and GBFS) and BGWNP increased AAM's strength compared to that of the control mixture for all scenarios. In addition, the findings also demonstrated that the replacement of FA by BGWNP was the most significant, while the effect of GBFS replacement by BGWNP was less significant. In particular, the highest improvement in compressive strength was recorded when FA, GBFS, and BGWNP were 61.6%, 30%, and 8.4%, respectively. Furthermore, the results of ANOVA (p values < 0.0001 and high F-values) as well as several statistical validation methods (R > 0.9, RAE < 0.1, RSE < 0.013, and RRSE < 0.116) confirmed that all the models were robust, reliable, and significant. Similarly, the data variation was found to be less than 5%, and the difference between the predicted R2 and adj. R2 was very small (<0.2), thus confirming that the proposed non-linear quadratic equations had the capability to predict for further observation. In conclusion, the use of BGWNP in AAM could act as a beneficial and sustainable strategy, not only to address environmental issues (e.g., landfill) but to also enhance strength properties.
  8. Ali LA, Jemon K, Latif NA, Bakar SA, Alwi SSS
    Biomedicine (Taipei), 2022;12(3):1-11.
    PMID: 36381191 DOI: 10.37796/2211-8039.1326
    Background: Type 2 diabetes mellitus (T2DM) is a chronic metabolic syndrome that is rapidly increasing across the world, especially in Malaysia. Leptin plays a vital role in the regulation of metabolism through its effect on peripheral tissues. G2548A polymorphism in the LEP gene promoter has been associated with insulin resistance, leptin, and type 2 diabetes mellitus across different population, but has not been inclusively reported within the Malaysian population.

    Objective: Thus, our study aimed to investigate the impact of G2548A polymorphism on serum leptin levels and insulin resistance among Malaysian T2DM patients.

    Methods: This case-control study involved 150 T2DM patients and 150 non-diabetic volunteers from ethnic Malays, Chinese and Indians. Genotyping of G2548A polymorphism was carried out using PCR-RFLP. Serum leptin and insulin levels were determined via ELISA. ANOVA and Chi-square tests were used to determine the distribution of genotypes and allelic frequencies based on serum leptin and insulin levels.

    Results: Frequency of AA genotype and A allele of G2548A variant were significantly (P < 0.05) higher in T2DM patients of Malay and Indian ethnicities (4%, 35%, and 36%, 57%, respectively) as compared to the control groups (0%, 22%, and 18%, 35%, respectively). Fasting serum leptin levels were significantly (P < 0.001) higher in T2DM patients compared to non-diabetic subjects (166.78 pg/ml, 101.94 pg/ml, respectively). Additionally, elevated serum leptin, insulin levels, and BMI in diabetic patients were found to be associated with the AA genotype of this variant, compared to GG, and GA genotypes (P < 0.05).

    Conclusion: Our findings suggest a significant association between G2548A polymorphism among Malaysian T2DM subjects, particularly among Malay and Indian ethnic groups. Moreover, the A allele frequency of the G2548A variant significantly increased the risk of T2DM and is significantly associated with increased serum leptin, insulin levels, and elevated BMI.

  9. Altowayti WAH, Algaifi HA, Bakar SA, Shahir S
    Ecotoxicol Environ Saf, 2019 May 15;172:176-185.
    PMID: 30708229 DOI: 10.1016/j.ecoenv.2019.01.067
    Globally, the contamination of water with arsenic is a serious health issue. Recently, several researches have endorsed the efficiency of biomass to remove As (III) via adsorption process, which is distinguished by its low cost and easy technique in comparison with conventional solutions. In the present work, biomass was prepared from indigenous Bacillus thuringiensis strain WS3 and was evaluated to remove As (III) from aqueous solution under different contact time, temperature, pH, As (III) concentrations and adsorbent dosages, both experimentally and theoretically. Subsequently, optimal conditions for As (III) removal were found; 6 (ppm) As (III) concentration at 37 °C, pH 7, six hours of contact time and 0.50 mg/ml of biomass dosage. The maximal As (III) loading capacity was determined as 10.94 mg/g. The equilibrium adsorption was simulated via the Langmuir isotherm model, which provided a better fitting than the Freundlich model. In addition, FESEM-EDX showed a significant change in the morphological characteristic of the biomass following As (III) adsorption. 128 batch experimental data were taken into account to create an artificial neural network (ANN) model that mimicked the human brain function. 5-7-1 neurons were in the input, hidden and output layers respectively. The batch data was reserved for training (75%), testing (10%) and validation process (15%). The relationship between the predicted output vector and experimental data offered a high degree of correlation (R2 = 0.9959) and mean squared error (MSE; 0.3462). The predicted output of the proposed model showed a good agreement with the batch work with reasonable accuracy.
  10. Amini P, Abdullah M, Seng LS, Karunakaran T, Hani N, Bakar SA, et al.
    Int Forum Allergy Rhinol, 2016 Jun;6(6):624-30.
    PMID: 26919193 DOI: 10.1002/alr.21442
    BACKGROUND: The number of available reports regarding the influence of ethnicity on clinical features of allergic rhinitis (AR), especially disease severity in tropical climates, is limited. We aimed to compare clinical parameters and disease severity in AR patients of different ethnicities.

    METHODS: Malay, Chinese, and Indian AR patients (n = 138) with confirmed sensitivity to Dermatophagoides pteronyssinus, Dematophagoides farinae, and Blomia tropicalis were tested for mite-specific immunoglobulin E (sIgE) levels. A detailed questionnaire was used to collect data on nasal symptom score (NSS), ocular symptom score (OSS), sum of symptoms score (SSS), quality of life score (QLS), symptomatic control score (SCS), and total sum of scores (TSS) and correlate the derived data with patients' demography, mite-polysensitivity, and sIgE levels.

    RESULTS: AR-related symptoms were most severe in Malays and least in Chinese (p < 0.01). Age (r = 0.516 to 0.673, p < 0.05) and duration of AR (r = 0.635 to 0.726, p < 0.01) correlated positively with severity domains (NSS, SSS, QLS, and TSS) in Chinese. Duration of concurrent allergies was highest in Malays (p < 0.05). Polysensitivity predicted increased sIgE levels in Malays (r = 0.464 to 0.551, p < 0.01) and Indians (r = 0.541 to 0.645, p < 0.05) but affected NSS, SSS, and TSS only in Indians (r = 0.216 to 0.376, p < 0.05). sIgE levels were lowest among Chinese but correlated strongly with NSS, OSS, SSS, and TSS (r = 0408 to 0.898, p < 0.05).

    CONCLUSION: Clinical parameters in AR may be influenced by race. Symptoms were most severe among Malays but did not correlate with other variables examined. Although Indian ethnicity did not impact disease severity, duration of concurrent allergies and mite-polysensitivity was associated with more severe disease. Age, duration of disease, and sIgE levels may be useful indicators of disease severity in Chinese.

  11. Ardyani T, Mohamed A, Bakar SA, Sagisaka M, Umetsu Y, Mamat MH, et al.
    J Colloid Interface Sci, 2019 Jun 01;545:184-194.
    PMID: 30878784 DOI: 10.1016/j.jcis.2019.03.012
    HYPOTHESIS: The compatibility of surfactants and graphene surfaces can be improved by increasing the number of aromatic groups in the surfactants. Including aniline in the structure may improve the compatibility between surfactant and graphene further still. Surfactants can be modified by incorporating aromatic groups in the hydrophobic chains or hydrophilic headgroups. Therefore, it is of interest to investigate the effects of employing anilinium based surfactants to disperse graphene nanoplatelets (GNPs) in natural rubber latex (NRL) for the fabrication of electrically conductive nanocomposites.

    EXPERIMENTS: New graphene-philic surfactants carrying aromatic moieties in the hydrophilic headgroups and hydrophobic tails were synthesized by swapping the traditional sodium counterion with anilinium. 1H NMR spectroscopy was used to characterize the surfactants. These custom-made surfactants were used to assist the dispersion of GNPs in natural rubber latex matrices for the preparation of conductive nanocomposites. The properties of nanocomposites with the new anilinium surfactants were compared with commercial sodium surfactant sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and the previously synthesized aromatic tri-chain sodium surfactant TC3Ph3 (sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3phenylpropoxy)carbonyl) pentane-2-sulfonate). Structural properties of the nanocomposites were studied using Raman spectroscopy, field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). Electrical conductivity measurements and Zeta potential measurements were used to assess the relationships between total number of aromatic groups in the surfactant molecular structure and nanocomposite properties. The self-assembly structure of surfactants in aqueous systems and GNP dispersions was assessed using small-angle neutron scattering (SANS).

    FINDINGS: Among these different surfactants, the anilinium version of TC3Ph3 namely TC3Ph3-AN (anilinium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3phenylpropoxy)carbonyl) pentane-2-sulfonate) was shown to be highly efficient for dispersing GNPs in the NRL matrices, increasing electrical conductivity eleven orders of magnitude higher than the neat rubber latex. Comparisons between the sodium and anilinium surfactants show significant differences in the final properties of the nanocomposites. In general, the strategy of increasing the number of surfactant-borne aromatic groups by incorporating anilinium ions in surfactant headgroups appears to be effective.

  12. Azhar NA, Ghozali SZ, Abu Bakar SA, Lim V, Ahmad NH
    Toxicol In Vitro, 2020 Sep;67:104910.
    PMID: 32526345 DOI: 10.1016/j.tiv.2020.104910
    Application of silver nanoparticles serves as a new approach in cancer treatment due to its unique features. Biosynthesis of silver nanoparticles using plant is advantageous since they are easily accessible, nontoxic and produce quicker reaction compared to other methods. To evaluate the cytotoxicity, mechanism of cell death and DNA damage of biosynthesized Catharanthus roseus-silver nanoparticles on human liver cancer (HepG2) cells. The antiproliferative activity of Catharanthus roseus‑silver nanoparticles was measured using MTT assay. The cytotoxic effects were further evaluated by measuring nitric oxide and reactive oxygen species (ROS). The mechanism of cell death was determined by annexin-FITC/propidium iodide, mitochondrial membrane potential (MMP) and cell cycle assays. The assessment of DNA damage was evaluated using Comet assay method. The uptake of the nanoparticles were evaluated by Transmission Electron Microscopy (TEM). Catharanthus roseus‑silver nanoparticles has inhibited the proliferation of HepG2 cells in a time-dependent manner with a median IC50 value of 3.871 ± 0.18 μg/mL. The concentration of nitrite and ROS were significantly higher than control. The cell death was due to apoptosis associated with MMP loss, cell cycle arrest, and extensive DNA damage. TEM analysis indicated the presence of free nanoparticles and endosomes containing the nanoparticles. The findings show that Catharanthus roseus‑silver nanoparticles have produced cytotoxic effects on HepG2 cells and thus may have a potential to be used as an anticancer treatment, particularly for hepatocellular carcinoma.
  13. Azhar NA, Abu Bakar SA, Citartan M, Ahmad NH
    World J Hepatol, 2023 Mar 27;15(3):393-409.
    PMID: 37034237 DOI: 10.4254/wjh.v15.i3.393
    BACKGROUND: The demand for the development of cancer nanomedicine has increased due to its great therapeutic value that can overcome the limitations of conventional cancer therapy. However, the presence of various bioactive compounds in crude plant extracts used for the synthesis of silver nanoparticles (AgNPs) makes its precise mechanisms of action unclear.

    AIM: To assessed the mRNA transcriptome profiling of human HepG2 cells exposed to Catharanthus roseus G. Don (C. roseus)-AgNPs.

    METHODS: The proliferative activity of hepatocellular carcinoma (HepG2) and normal human liver (THLE3) cells treated with C. roseusAgNPs were measured using MTT assay. The RNA samples were extracted and sequenced using BGIseq500 platform. This is followed by data filtering, mapping, gene expression analysis, differentially expression genes analysis, Gene Ontology analysis, and pathway analysis.

    RESULTS: The mean IC50 values of C. roseusAgNPs on HepG2 was 4.38 ± 1.59 μg/mL while on THLE3 cells was 800 ± 1.55 μg/mL. Transcriptome profiling revealed an alteration of 296 genes. C. roseusAgNPs induced the expression of stress-associated genes such as MT, HSP and HMOX-1. Cellular signalling pathways were potentially activated through MAPK, TNF and TGF pathways that are responsible for apoptosis and cell cycle arrest. The alteration of ARF6, EHD2, FGFR3, RhoA, EEA1, VPS28, VPS25, and TSG101 indicated the uptake of C. roseus-AgNPs via both clathrin-dependent and clathrin-independent endocytosis.

    CONCLUSION: This study provides new insights into gene expression study of biosynthesised AgNPs on cancer cells. The cytotoxicity effect is mediated by the aberrant gene alteration, and more interestingly the unique selective antiproliferative properties indicate the C. roseusAgNPs as an ideal anticancer candidate.

  14. Farooq SM, Boppana NB, Devarajan A, Asokan D, Sekaran SD, Shankar EM, et al.
    PLoS One, 2014;9(4):e93056.
    PMID: 24691130 DOI: 10.1371/journal.pone.0093056
    Oxalate toxicity is mediated through generation of reactive oxygen species (ROS) via a process that is partly dependent on mitochondrial dysfunction. Here, we investigated whether C-phycocyanin (CP) could protect against oxidative stress-mediated intracellular damage triggered by oxalate in MDCK cells. DCFDA, a fluorescence-based probe and hexanoyl-lysine adduct (HEL), an oxidative stress marker were used to investigate the effect of CP on oxalate-induced ROS production and membrane lipid peroxidation (LPO). The role of CP against oxalate-induced oxidative stress was studied by the evaluation of mitochondrial membrane potential by JC1 fluorescein staining, quantification of ATP synthesis and stress-induced MAP kinases (JNK/SAPK and ERK1/2). Our results revealed that oxalate-induced cells show markedly increased ROS levels and HEL protein expression that were significantly decreased following pre-treatment with CP. Further, JC1 staining showed that CP pre-treatment conferred significant protection from mitochondrial membrane permeability and increased ATP production in CP-treated cells than oxalate-alone-treated cells. In addition, CP treated cells significantly decreased the expression of phosphorylated JNK/SAPK and ERK1/2 as compared to oxalate-alone-treated cells. We concluded that CP could be used as a potential free radical-scavenging therapeutic strategy against oxidative stress-associated diseases including urolithiasis.
  15. Han LM, Haron Z, Yahya K, Bakar SA, Dimon MN
    PLoS One, 2015;10(4):e0120667.
    PMID: 25875019 DOI: 10.1371/journal.pone.0120667
    Strategic noise mapping provides important information for noise impact assessment and noise abatement. However, producing reliable strategic noise mapping in a dynamic, complex working environment is difficult. This study proposes the implementation of the random walk approach as a new stochastic technique to simulate noise mapping and to predict the noise exposure level in a workplace. A stochastic simulation framework and software, namely RW-eNMS, were developed to facilitate the random walk approach in noise mapping prediction. This framework considers the randomness and complexity of machinery operation and noise emission levels. Also, it assesses the impact of noise on the workers and the surrounding environment. For data validation, three case studies were conducted to check the accuracy of the prediction data and to determine the efficiency and effectiveness of this approach. The results showed high accuracy of prediction results together with a majority of absolute differences of less than 2 dBA; also, the predicted noise doses were mostly in the range of measurement. Therefore, the random walk approach was effective in dealing with environmental noises. It could predict strategic noise mapping to facilitate noise monitoring and noise control in the workplaces.
  16. Hassan H, Bakar SA, Halim KN, Idris J, Saad FF, Nordin AJ
    Curr Radiopharm, 2016;9(2):121-7.
    PMID: 26239237
    BACKGROUND AND OBJECTIVE: 18F-Fluorocholine has been suggested as one of the reputable imaging tracers for diagnosis of prostate tumour in Positron Emission Tomography / Computed Tomography (PET/CT) modality. Nevertheless, it has never been synthesised in Malaysia. We acknowledged that the major problem with 18F-Fluorocholine is due to its relatively low radiochemical yield at the end of synthesis (EOS). Therefore, this article presents improved 18FFluorocholine radiochemical yields after carrying out optimisation on azeotropic drying of 18F-Fluorine.

    METHODS: In the previous study, the azeotropic drying of non-carrier-added (n.c.a) 18F-Fluorine in the reactor was conducted at atmospheric pressure (0 atm) and shorter duration time. In this study, however, the azeotropic drying of non-carried-added (n.c.a) 18FFluorine was made at a high vacuum pressure (- 0.65 to - 0.85 bar) with an additional time of 30 seconds. At the end of the synthesis, the mean radiochemical yield was statistically compared between the two azeotropic drying conditions so as to observe whether the improvement made was significant to the radiochemical yield.

    RESULTS: From the paired sample t-test analysis, the improvement done to the azeotropic drying of non-carrier-added (n.c.a) 18F-Fluorine was statistically significant (p < 0.05). With the improvement made, the 18F-Fluorcholine radiochemical yield was found to have increase by one fold.

    CONCLUSION: Improved 18F-Fluorocholine radiochemical yields were obtained after the improvement had been done to the azeotropic drying of non-carrier-added (n.c.a) 18F-Fluorine. It was also observed that improvement made to the azeotropic drying of non-carrier-added (n.c.a) 18F-Fluorine did not affect the 18F-Fluorocholine quality control analysis.

  17. Hearn AJ, Ross J, Bernard H, Bakar SA, Hunter LT, Macdonald DW
    PLoS One, 2016;11(3):e0151046.
    PMID: 27007219 DOI: 10.1371/journal.pone.0151046
    The marbled cat Pardofelis marmorata is a poorly known wild cat that has a broad distribution across much of the Indomalayan ecorealm. This felid is thought to exist at low population densities throughout its range, yet no estimates of its abundance exist, hampering assessment of its conservation status. To investigate the distribution and abundance of marbled cats we conducted intensive, felid-focused camera trap surveys of eight forest areas and two oil palm plantations in Sabah, Malaysian Borneo. Study sites were broadly representative of the range of habitat types and the gradient of anthropogenic disturbance and fragmentation present in contemporary Sabah. We recorded marbled cats from all forest study areas apart from a small, relatively isolated forest patch, although photographic detection frequency varied greatly between areas. No marbled cats were recorded within the plantations, but a single individual was recorded walking along the forest/plantation boundary. We collected sufficient numbers of marbled cat photographic captures at three study areas to permit density estimation based on spatially explicit capture-recapture analyses. Estimates of population density from the primary, lowland Danum Valley Conservation Area and primary upland, Tawau Hills Park, were 19.57 (SD: 8.36) and 7.10 (SD: 1.90) individuals per 100 km2, respectively, and the selectively logged, lowland Tabin Wildlife Reserve yielded an estimated density of 10.45 (SD: 3.38) individuals per 100 km2. The low detection frequencies recorded in our other survey sites and from published studies elsewhere in its range, and the absence of previous density estimates for this felid suggest that our density estimates may be from the higher end of their abundance spectrum. We provide recommendations for future marbled cat survey approaches.
  18. Idris NJ, Bakar SA, Mohamed A, Muqoyyanah M, Othman MHD, Mamat MH, et al.
    Environ Sci Pollut Res Int, 2021 Feb;28(6):6966-6979.
    PMID: 33025441 DOI: 10.1007/s11356-020-10904-y
    In this work, sand/zinc oxide (ZnO)/titanium dioxide (TiO2)-based photocatalysts were hybridized with graphene oxide (GO) and GO_multi-walled carbon nanotubes (MWCNTs) hybrid solution. The novel hybrid was then used in photocatalysis to degrade dye contamination. The nanocomposite photocatalyst was initially fabricated by growing ZnO nanorods (NRs) via sol-gel immersion followed by synthesizing TiO2 NRs for different times (5 and 20 h) using a hydrothermal method on sand as a substrate. Prior to the hybridization, the initial GO was synthesized using electrochemical exfoliation and further mixed with 1 wt% MWCNTs to form GO_MWCNTs hybrid solution. The synthesized GO and GO_MWCNTs hybrid solution were then incorporated onto sand/ZnO/TiO2 nanocomposite-based photocatalysts through immersion. Various sand/ZnO/TiO2-based photocatalysts were then tested for methylene blue (MB) dye degradation within 3 days. On the basis of UV-Vis measurement, the highest MB degradation was achieved by using sand/ZnO NRs/TiO2 NRs (5 h)/GO_MWCNTs (92.60%). The high surface area and high electrical conductivity of GO_MWCNTs prolonged the lifetime of electron/hole separation and thus enhanced the photocatalytic performance.
  19. Jamaluddin NA, Mohamed A, Bakar SA, Ardyani T, Sagisaka M, Saito H, et al.
    Phys Chem Chem Phys, 2021 Sep 15;23(35):19313-19328.
    PMID: 34524298 DOI: 10.1039/d1cp02206g
    Previously, surfactant-assisted exfoliated graphene oxide (sEGO) formed with the triple-chain surfactant TC14 (sodium 1,4-bis(neopentyloxy)-3-(neopentylcarbonyl)-1,4-dioxobutane-2-sulfonate) was applied in wastewater treatment. The extent of dye-removal and the adsorption capacity of the sEGO formed with this triple-chain surfactant outperformed those of two other systems, namely, the di-chain version of TC14 (AOT14; sodium 1,2-bis-(2,2-dimethyl-propoxycarbonyl)-ethanesulfonate) and the single-chain surfactant sodium n-dodecylsulfate. In the present study, to further optimise the surfactant chemical structure, the sodium ion of TC14 was substituted with 1-butyl-3-methyl-imidazolium (BMIM) generating surfactant ionic liquids (SAILs; 1-butyl-3-imidazolium 1,4-bis(neopentyloxy)-3-(neopentyloxycarbonyl)-1,4-dioxobutane-2-sulfonate), hereafter denoted as BMIM-TC14. This SAIL, together with nanofibrillated kenaf cellulose (NFC), was used to electrochemically exfoliate graphite, yielding BMIM-TC14 sEGO/NFC composites. These highly hydrophobic polymer composites were then used for the removal of methylene blue (MB) from aqueous solution. 1H NMR spectroscopy was used to elucidate the structure of the synthesised SAILs. The morphologies of the resulting nanocomposites were investigated using Raman spectroscopy, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy. Analysis using small-angle neutron scattering was performed to examine the aggregation behaviour of sEGO and custom-made SAILs. Zeta potential, surface tension, and dynamic light-scattering measurements were used to study the aqueous properties and colloidal stability of the suspension. Amongst the surfactants tested, BMIM-TC14 sEGO/NFC exhibited the highest MB adsorption ability, achieving 99% dye removal under optimum conditions. These results highlight the importance of modifying the hydrophilic moieties of amphiphilic compounds to improve the performance of sEGO/NFC composites as effective adsorbents for wastewater treatment.
  20. Jumat F, Rahman MHA, Bakar SA, Shakri NA, Kamaruzaman R, Bakar NAA, et al.
    Data Brief, 2023 Aug;49:109383.
    PMID: 37600135 DOI: 10.1016/j.dib.2023.109383
    Rice straw is one of the most abundant biomass wastes derived from rice cultivation activities. The current rice straw management practice during the wet (rainy) season in Malaysia involves the integration of straw into the soil. This practice offers both advantages and disadvantages to rice farmers and the environment. Straw integration may improve nutrient availability while concurrently causing high greenhouse gas (GHG) emissions due to the increase in soil carbon activity. In this work, the use of microbial substrate to enhance the degradation of straw was compared to an existing technique that used no additional inputs during soil integration. The data collected consisted of overall microbial enzyme production, soil organic carbon, soil nitrogen content, seasonal greenhouse gas emissions, plant characteristics, and crop yield. In brief, these data can be used as means of demonstrating the effects of improved straw degradation during the pre-season on the overall GHG emissions during the planting season.
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