19672 research outputs found
Sort by
Optical characterization of different waist diameter on microfiber loop resonator humidity sensor
No full textIn this paper, the effect of different waist diameter on silica microfiber loop resonator (MLR) relative humidity (%RH) sensor is reported. The silica fiber was tapered to vary the waist diameter to 3 μm, 4 μm, 5 μm,7 μm, 8 μm and 10 μm using flame brushing technique. The MLR with a 300 μm diameter loop was formed by manually twisted the tapered fiber under an optical microscope into a self-touching loop. Initially, the effect of whispering gallery modes (WGMs) on the MLR was observed. Transmission mode spectra were observed to determine the number of resonated wavelength and quality factor (Q-factor). The Q-factor is observed to be >105 for all samples and MLR with 3 μm diameter achieve the highest Q-factor value. A significant response to %RH from 35% to 85% was observed due to the change of refractive index between the MLR and the surrounding medium resulting different light attenuation in the microfiber. The sensitivity increased by a factor of 12.2 for the MLR with diameter of 7 μm as compared to the smaller diameter MLRs and a factor of 13.7 as compared to straight microfiber (SmF). As for resolution, the MLR with waist diameter of 7 μm improve by a factor of 5 as compared to the smaller waist diameter and a factor of 6.5 as compared to SmF. The proposed humidity sensor employs the microfiber loop resonator without any sensitive material coated on it which reduced the complexity during the fabrication and manufacturing process. The reported results may contribute to the optimal waist diameter of microfiber loop resonators for humidity sensing application
Evolution of structural and magnetic properties of nickel oxide nanoparticles: Influence of annealing ambient and temperature
No full textNickel oxide (NiO) nanoparticles (NPs) are synthesized using the sol-gel method. The effect of annealing atmosphere type, including air, O2 and annealing temperature (TA) on the structural, morphological and magnetic properties of NiO NPs was investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) analysis. For this purpose, NiO NPs are annealed at 400, 500, 600, 700 and 800 °C. The magnetic properties of the NPs change as a result of increasing crystallite size in terms of TA in both atmospheres. These variations are different according to the type of the annealing atmosphere. At lower temperatures (TA < 600 °C), the NPs that annealed in the O2 atmosphere have higher crystallinity, larger lattice constant, and lower magnetization and coercivity. At higher temperatures, the structural and magnetic properties of the samples in both atmospheres are more similar
Synthesis, X-ray diffraction studies, thermal behavior and catalytic investigation of Cu(II) complexes for levulinic acid-based polyol esters
No full textThree new copper(II) complexes [Cu(Phe)(Phen)Cl].H2O (1), [Cu(Tyr)(Phen)Cl].H2O (2) and [Cu(Phe)(Tyr)Cl].H2O (3) (Phe = L-phenylalanine, Tyr = L-tyrosine and Phen = 1,10-phenanthroline) have been synthesized with aromatic amino acids and versatile organic 1,10-phenanthroline as mixed ligands and characterized by elemental analysis, FTIR, magnetic susceptibility, single crystal-XRD, powder-XRD, TGA/DTA and SEM techniques. The structural analysis of the complexes revealed that L-phenylalanine and L-tyrosine was coordinated to Cu(II) ion through amino nitrogen and carboxylate oxygen whereas, 1,10-phenanthroline was coordinated by the two nitrogen atoms. In all the cases, the Cu(II) ion has occupied the centre of the square pyramidal coordination, being equatorially bonded by both amino acids and 1,10-phenanthroline, while axially by chlorine atom. In addition, the thermal analysis (TGA/DTA) indicated the presence of lattice water molecules outside the coordination sphere. The catalytic activity of the synthesized complexes was further investigated via esterification of polyols (e.g., neopentyl glycol, trimethylolpropane and pentaerythritol) with biomass-derived levulinic acid (model acid) under mild reaction conditions. Indeed, the esterification reaction reveals that the Cu(II) complex with L-phenylalanine and 1,10-phenanthroline ligands exhibited a significantly high catalytic activity among them
Prevalence and correlates of physical inactivity among older adults in Malaysia: Findings from the National Health and Morbidity Survey (NHMS) 2015
No full textMalaysia has an increasingly aging population. Despite the substantial benefits of physical activity for healthy aging, older adults are considered the most physically inactive segment of the Malaysian population. The purpose of this study was to determine the prevalence of physical inactivity among older adults in Malaysia and its correlates. We analysed data on adults aged ≥60 years (n = 3790) from the National Health and Morbidity Survey (NHMS) 2015, a cross-sectional, nationwide population-based survey covering information on socio-demographic characteristics, physical activity and other lifestyle-related variables, health conditions, and functional limitations. Individuals included in this study were classified as physically active or physically inactive. Logistic regression was used to determine factors associated with physical inactivity. The overall prevalence of physical inactivity among older adults aged ≥60 years old was 48.8%. Physical inactivity was significantly more prevalent among females, older age groups, Indians, those being single/widowed/divorced, those with no formal education, those who reported high sedentary time (≥7 h/day), those with diabetes, anaemia, and functional limitations (p < 0.001). In fully adjusted analyses, females, older age, high household income (≥MYR4000), inadequate fruits and vegetables consumption (<5 servings/day), high sedentary time, having diabetes, and having mobility impairment were all associated with physical inactivity. Approximately half of the Malaysian older population are physically inactive. Identifying the correlates of physical inactivity among Malaysian older adults will help to develop public health policies and interventions that encourage active living among older people and promote healthy aging in Malaysia
Mechanochemistry approach to produce in-situ tungsten borides and carbides nanopowders: Experimental study and modeling
No full textMechanically-induced self-sustaining reactions (MSRs) in WO3–B2O3–Mg–C powder mixtures were investigated in terms of reductant content. Also, two different predictive intelligent-based techniques including Adaptive Neuro-Fuzzy Inference System (ANFIS) and Multi-Layer Perceptron Artificial Neural Network (MLP-ANN) were developed to estimate the structural features of the mechanosynthesized powders, where different statistical analysis were performed to prove the precision and robustness of proposed models. The phase compositions were changed as the concentration of ductile reductant (Mg) reduced in the system. Accordingly, the fraction of crystalline phases was dramatically altered after the leaching process. The structural assessment showed that the dislocation density significantly varied as the graphite content increased, however, the rate of these alterations was not linear. FESEM observations indicated that the leached product had a typical flower-like cluster configuration, which consisted of loosely organized nano-sheets with a side length and thickness of around 250 and 12 nm, respectively. Meanwhile, the results achieved from the intelligent-based techniques showed that both ANFIS and ANN are very powerful in estimating the structural characteristics of the mechanosynthesized powders. However, ANFIS was more accurate than MLP-ANN
Malaysian urban poor adoption of e-government applications and their satisfaction
No full textThe aim of this research is to examine factors that influence citizens’ adoption of the e-government applications in Malaysia. In addition, their satisfaction is also analyzed. The research model was developed based on the integration of the Technology Acceptance Model and Diffusion of Innovation as well as trust in the government, information quality, computer self-efficacy, and customer satisfaction constructs regarding e-government applications in Malaysia. The data was collected using a Likert-scale questionnaire from 801 Malaysian urban poor citizens. Results revealed that compatibility, relative advantage, image, trust in the government, computer self-efficacy, and customer satisfaction have significant impacts on the use of e-government applications. In turn, customer satisfaction was itself positively influenced by the use of e-government applications. This research has provided in-depth understanding of critical factors in enhancing adoption and citizens’ satisfaction with e-government applications. © 2019, © 2019 The Author(s). This open access article is distributed under a Creative Commons Attribution (CC-BY) 4.0 license
Synthesis and characterization of magnetic graphene oxide for arsenic removal from aqueous solution
No full textA magnetic graphene oxide (MGO) was developed for the adsorption of As(III) from aqueous solution. The characteristics of MGO were investigated using Fourier-transform infrared (FTIR), X-ray diffraction and field emission scanning electron microscope-E/energy-dispersive X-ray analyses. Batch adsorption experiments were designed using central composite design, and the effects of adsorbent dosage, pH, contact time and concentration of As(III) were investigated. The MGO showed an excellent performance, removing up to 99.95% of As(III) under the following condition: initial As(III) concentration = 100 mg/L, pH = 7, adsorbent dosage = 0.3 g/L and contact time = 77 min. MGO dosage and initial pH were the most significant parameters influencing the process performance. FTIR analysis of the used adsorbent confirms the adsorption of As(III) through complexation between surface functional groups of the MGO and the oxyanions of As(III). The adsorbent maintained a significant level of performance even after four cycles of adsorption. Thus, the developed MGO has the potential to be used for the abatement of arsenic pollution. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group
Dechlorination of polychlorobiphenyl degradation metabolites by a recombinant glutathione S-transferase from Acidovorax sp. KKS102
No full textA glutathione S-transferase (GST) with a potential dehalogenation function against various organochlorine substrates was identified from a polychlorobiphenyl (PCB)-degrading organism, Acidovorax sp. KKS102. A homolog of the gene BphK (biphenyl upper pathway K), named BphK-KKS, was cloned, purified and biochemically characterized. Bioinformatic analysis indicated several conserved amino acids that participated in the catalytic activity of the enzyme, and site-directed mutagenesis of these conserved amino acids revealed their importance in the enzyme's catalytic activity. The wild-type and mutant (C10F, K107T and A180P) recombinant proteins displayed wider substrate specificity. The wild-type recombinant GST reacted towards 1-chloro-2,4-dinitrobenzene (CDNB), ethacrynic acid, hydrogen peroxide and cumene hydroperoxide. The mutated recombinant proteins, however, showed significant variation in specific activities towards the substrates. A combination of a molecular docking study and a chloride ion detection assay showed potential interaction with and a dechlorination function against 2-, 3- and 4-chlorobenzoates (metabolites generated during PCB biodegradation) in addition to some organochlorine pesticides (dichlorodiphenyltrichloroethane, endosulfan and permethrin). It was demonstrated that the behavior of the dechlorinating activities varied among the wild-type and mutant recombinant proteins. Kinetic studies (using CDNB and glutathione) showed that the kinetic parameters K m , V max , K cat and K m /K cat were all affected by the mutations. While C10F and A180P mutants displayed an increase in GST activity and the dechlorination function of the enzyme, the K107T mutant displayed variable results, suggesting a functional role of Lys107 in determining substrate specificity of the enzyme. These results demonstrated that the enzyme should be valuable in the bioremediation of metabolites generated during PCB biodegradation. © 2018 The Authors. Published by FEBS Press and John Wiley & Sons Ltd
Role of sonication time on thermal behaviour and dynamic mechanical analysis of NiZn ferrite incorporated PLA/LNR nanocomposite
No full textThe investigation on thermal properties of polylactic acid/liquid natural rubber (PLA/LNR) blend embedded with nickel zinc (NiZn) ferrite nanoparticles at various loading (1-5 wt%) and treated with different ultrasonication time (1-2 h) is the main core of this study. The novel NiZn nanocomposite based on the matrix of PLA:LNR with a ratio of 90:10 was fabricated via melt blending technique with the aids of ultrasonication. The effects of nanofiller loading and ultrasonic treatment on nanocomposite were examined by scanning electron microscopy, differential scanning calorimetry and dynamic mechanical analyser. The results revealed that the thermal properties of PLA/LNR matrix have improved with incorporation of nanoparticles in which improvement was observed until an optimum level at 4 wt% NiZn ferrite within 1 h of ultrasonic treatment. The optimum ultrasonication for 1 h is believed to be sufficient to promote a good dispersion of NiZn ferrite nanoparticles within the PLA/LNR and in order to enhance the thermal stability, which makes it potentially to be used in electronic applications. © Indian Academy of Sciences
vFog: A Vehicle-Assisted Computing Framework for Delay-Sensitive Applications in Smart Cities
No full textThe inception of the smart cities concept provides a compelling platform to support innovative applications. It provides distinctive view of cities, where mobile devices, pedestrians, and electronic gadgets can communicate with each other to build an effective urban environment to further improve the living standards. Similarly, the role of the Internet of Things (IoT) and vehicular computing has emerged due to smart cities. This is further complemented by edge and fog computing architectures. The emerging concept of vehicular fog computing has enabled the platform to support delay-sensitive applications and to reduce the workload on the backend networks. Vehicular fog computing is a paradigm that touches the boundaries of thinking vehicles as an infrastructures-as-a-service. The use of vehicles to provide computation on-the-move poses various challenges. The vehicles with onboard computing equipment can facilitate delay-sensitive applications. These vehicles can act as an edge device to reduce the load from a backbone network. However, due to continuous mobility, it is difficult to use traditional frameworks to distribute the computation task among vehicles. In this paper, we propose a framework termed vFog. The vFog is designed to provide computing facilities from nearby fog vehicles. The framework utilizes the onboard computing facility of vehicles without the support of roadside units (RSUs). Moreover, the proposed framework handles churn behavior and supports multi-hop communication to improve the task delivery ratio. The proposed framework allows researchers to benchmark their own task distribution algorithms over the dynamic vehicular networks. © 2013 IEEE