19672 research outputs found
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New sporopollenin-based β-cyclodextrin functionalized magnetic hybrid adsorbent for magnetic solid-phase extraction of nonsteroidal anti-inflammatory drugs from water samples
No full textA magnetic solid-phase extraction (MSPE)procedure on the newly synthesized magnetic β-cyclodextrin functionalized with toluene diisocyanate (TDI)as a linker and further modified with bio-polymeric spores of sporopollenin (MSp-TDI-βCD), was developed for the extraction of nonsteroidal anti-inflammatory drugs (NSAIDs), namely, indoprofen (INP), ketoprofen (KTP), ibuprofen (IBP)and fenoprofen (FNP)from water samples prior to their HPLC-DAD determination. The newly synthesized MSp-TDI-βCD was comprehensibly characterized using FT-IR, XRD, SEM-EDX, BET and VSM analyses. The separation of selected NSAIDs on MSp-TDI-βCD from aqueous solution was simply achieved by applying an external magnetic field via a permanent magnet. The MSPE parameters affecting extraction performance, i.e. sorbent dosage, sample volume, extraction and desorption time, type of organic eluent and volume and solution pH were investigated and optimized. The proposed method showed linear range between 0.5 and 500 ng ml-1, low limit of detection at S/N=3 (0.16-0.37 ng ml-1)and limit of quantification at S/N=10 (0.53-1.22 ng ml-1). The inter-day (n=15)and intra-day (n=5)precision for the proposed methods given by relative standard deviation (RSD%)was in the range of 2.5-4.0 and 2.1-5.5, respectively. The extraction recoveries of NSAIDs from environmental samples (tap, drinking and river water)ranged from 92.5% to 123.6%, with satisfactory precision (RSD% less than 12.4%)
Effect of conjugation and aromaticity of 3,6 di-substituted carbazoles on triplet energy and the implication of triplet energy in multiple-cyclic aromatic compounds
No full textIt is well-known that short conjugation is needed to obtain a high triplet energy. Carbazole has 3 fused rings and yet it has a high triplet energy. In order to illuminate the reason behind this, we synthesized a range of carbazole derivatives with substitution at the 3,6-positions. All carbazoles with phenyl moieties substituted at the 3,6-positions exhibit a lower triplet energy than that of carbazole itself. We also quantified the aromaticity of carbazole using the nucleus-independent chemical shift tensor. We discovered that the five-membered heterocyclic aromatic ring in carbazole has reduced aromaticity. This results in a reduced conjugation effect between the five-membered heterocyclic aromatic ring and the neighboring benzene rings. Inspired by this finding, the triplet energies of compounds with up to seven benzene units separated by heterocycles (furan, pyrrole, thiophene, silole, and phosphole) and cyclopentadiene were calculated using time-dependent density functional theory. A high triplet energy (>3 eV) can be obtained by alternating high aromaticity and reduced aromaticity in highly extended fused π systems containing furan and pyrrole. In tricyclic aromatic compounds (dibenzofuran, carbazole, fluorene, dibenzothiophene, 5H-benzo[b]phosphinedole and 9H-9-silafluorene) and their extended fused π systems that we have examined so far, the triplet energy is related to the electronegativity of the oxygen, nitrogen, carbon, sulfur, phosphorous and silicon atoms. These findings provide new intuitive insight related to the structures of molecules and the triplet energies, which could be useful in organic optoelectronics
Synthesis and Characterization of Castor Oil-Based Polyurethane Nanocomposites
No full textA series of castor oil-based polyurethane (PU) with and without the incorporation of Halloysite nanoclay as filler are synthesized via addition polymerization of polycaprolactone-diol (PCL) and methylene diphenyl diisocyante (MDI) as monomers. The PUs are characterized by using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric anaysis (TGA), differential scanning calorimetry (DSC), scanning electron microscope (SEM), and pencil hardness test. The TGA thermogram showed that the incorporation of castor oil affected the thermal stability of the PU matrices by 7–9% in reduction of the decomposition temperature; whereas the incorporation of Halloysite nanoclay into the PU matrices increased the thermal stability by 3–5% in the detection of higher decomposition temperature. The DSC thermograms of the castor-oil based PU and castor oil-based PU with Halloysite nanoclay showed reduction in glass transition temperature (Tg) by 13–33 and 8–14 °C, respectively as compared to pristine PU and castor-oil based PU. It is envisaged that the reduction in Tg is caused by the non-uniformity of dispersion of the Halloysite nanoclay throughout the PU matrices and hence, affected the mobility of the PU chains. The SEM images further confirmed the non-uniformity of dispersion of the Halloysite nanoclay in the PU films. Pencil hardness test indicated that the PU films coated on glass slides had lower than 1H hardness
3D CFD simulation and parametric study of a flat plate deflector for vertical axis wind turbine
No full textThree-dimensional numerical simulations have been performed to analyze the aerodynamic characteristics of a straight-bladed NACA0021 vertical axis wind turbine (VAWT). The unsteady flow CFD simulation was validated with the wind tunnel experiment data available in the literature. Sliding mesh method with the SST k-ω turbulence model was employed to simulate the rotational motion of the VAWT using ANSYS Fluent. The study showed a good agreement between the simulation and the wind tunnel testing. Further simulations were carried out to study the effects of a flat plate deflector being placed at the upwind of the VAWT by varying a few parameters including the position, the inclination angle and the length of the flat plate deflector. The simulations showed that the augmented flow occurred at the near wake region where the flow was accelerated and deflected by the deflector before impinging with the turbine; hence the coefficient of power (CP) of the VAWT improved significantly. However, the performance of the VAWT was highly dependent on the position of the deflector. From the simulation results, with the optimum parameters, the cycle-averaged coefficient of torque was increased about 47.10% higher compared to the VAWT without the deflector
Exploring the needs and challenges of parents and their children in childhood epilepsy care: A qualitative study
No full textBecause of the nature of epilepsy, and the unpredictability of seizure recurrence, epilepsy requires long-term treatment with medications. As a consequence, epilepsy has a negative pervasive impact in children with epilepsy (CWE), and their parents. Hence, our aim was to explore the needs and challenges of parents and their CWE. In-depth interviews (IDIs) were conducted with 15 families (12 mothers and 3 fathers) and 15 CWE (aged 8–18 years). Data were transcribed verbatim and thematically analyzed using the descriptive phenomenology approach. The experiences of parents and their CWE could be divided into two time frames: “experiences during a child's first seizure” and “experiences whilst growing up with epilepsy”. Parents’ main concerns and worries were regarding their child's physical health, psychological and emotional wellbeing, academic achievement, and future. The children's main concerns were restrictions imposed, their interpersonal relationship with peers, and being independent in the future. Parents reported that they needed epilepsy-related information, continuity of care, and a parental support group, while CWE reported that their main needs were independence and autonomy. The views of parents and their child with epilepsy were similar in physical functioning and academic achievement. However, parents and children had different views on how epilepsy impacted on the child emotionally, as well as behavioral and interpersonal relationship with peers
Landscape features and potential heat hazard threat: a spatial–temporal analysis of two urban universities
No full textUrban universities are a microcosm of urban built-up areas, such as cities, but with a much smaller scale of spatial resolution. Within universities, there are many types of landscape features exhibiting different heat absorption and transmission capacities. These landscape features generate spatial–temporal heat signatures, and the knowledge about landscape features and urban heat hazard on university campuses is limited. The objective of this research is an assessment of landscape features and the potential heat hazard threats of two urban universities in ASEAN, located in the centre of the equatorial region. The focus of this research is on urban heat hazards in two urban universities in ASEAN, the University of Malaysia in Kuala Lumpur and the University of Indonesia in Jakarta, within the context of the spatial–temporal behaviour of urban heat and the urban heat effects on the environment and human well-being on campuses. The spatial and temporal analysis used to answer the objective of this research via data-gathering methods from image satellite, ground trough, and human perception study. The UM campus and UI campus, both urban campuses, had similar landscape features but had different total percentage areas of these features. The UM campus was 59.1% covered by the densely vegetated surface landscape feature, a percentage lower than that of the UI campus, which was 65.3% vegetation covered. The temporal results for the UHS of the UM campus in 2013–2016 show a maximum temperature of 39 °C. Therefore, the UHS of the UI campus demonstrated temporal behaviour in 2013–2016, with a maximum temperature of 38 °C. The UHS behaviour of the UM campus and UI campus had an air surface temperature with a maximum average temperature of 33 °C. The air surface temperatures exceeding 32 °C at the UM campus (12 pm until 6 pm = 5 h) lasted for a longer time than those at the UI campus (12 pm until 3 pm = 3 h). This study showed that, based on the perceptions on both campuses, if temperatures exceeded 30 °C, respondents were very hot and very uncomfortable, which will impact health and decrease work or academic achievements, as perceptions of heat intensity impact human well-being. Students perceived that heat intensity impacted their health and they reported becoming tired and lethargic under maximum temperatures and were very hot and very uncomfortable, and this condition impacted their work activity. These results indicated that, at both the UM and UI campuses, heat intensity impacts human well-being, with risks associated with hot temperatures. These two urban campuses are significant for ASEAN university awareness of the urban heat hazard of the equatorial area
Pentocin MQ1: A Novel, Broad-Spectrum, Pore-Forming Bacteriocin From Lactobacillus pentosus CS2 With Quorum Sensing Regulatory Mechanism and Biopreservative Potential
No full textMicrococcus luteus, Listeria monocytogenes, and Bacillus cereus are major food-borne pathogenic and spoilage bacteria. Emergence of antibiotic resistance and consumer demand for foods containing less of chemical preservatives led to a search for natural antimicrobials. A study aimed at characterizing, investigating the mechanism of action and regulation of biosynthesis and evaluating the biopreservative potential of pentocin from Lactobacillus pentosus CS2 was conducted. Pentocin MQ1 is a novel bacteriocin isolated from L. pentosus CS2 of coconut shake origin. The purification strategy involved adsorption-desorption of bacteriocin followed by RP-HPLC. It has a molecular weight of 2110.672 Da as determined by MALDI-TOF mass spectrometry and a molar extinction value of 298.82 M -1 cm -1 . Pentocin MQ1 is not plasmid-borne and its biosynthesis is regulated by a quorum sensing mechanism. It has a broad spectrum of antibacterial activity, exhibited high chemical, thermal and pH stability but proved sensitive to proteolytic enzymes. It is potent against M. luteus, B. cereus, and L. monocytogenes at micromolar concentrations. It is quick-acting and exhibited a bactericidal mode of action against its targets. Target killing was mediated by pore formation. We report for the first time membrane permeabilization as a mechanism of action of the pentocin from the study against Gram-positive bacteria. Pentocin MQ1 is a cell wall-associated bacteriocin. Application of pentocin MQ1 improved the microbiological quality and extended the shelf life of fresh banana. This is the first report on the biopreservation of banana using bacteriocin. These findings place pentocin MQ1 as a potential biopreservative for further evaluation in food and medical applications
Topographical survey engineering education retrofitted by computer-aided 3D-printing
No full textDue to the sophisticated nature of contour lines on 2D drawings, students often find difficulties in visualizing three-dimensional interpretations of flat and 2D displays, especially when they attempt to comprehend topographic maps. This study aims to determine the issues encountered in topographical survey education that could be mitigated by 3D-printed models and to explore the effectiveness of hands-on 3D-printing exercises in real teaching practices by guiding students to design and fabricate 3D models using 3D-printing techniques. A mixed method combining quantitative and qualitative approaches has been employed including experiments and structured interview surveys. The qualitative ethnographic method through a qualitative experiment developed 3D-printed models for topographic education. Topographic maps were developed using Sketchup Version 8 software in order to fabricate the 3D topographic models. Hands-on 3D-printing exercises engender better understanding and appreciation of topographic maps among the students. This research demonstrates how 3D models could complement the conventional teaching using 2D maps in university education
Applied Artificial Bee Colony Optimization Algorithm in Fire Evacuation Routing System
No full textEvery minute counts in an event of fire evacuation where evacuees need to make immediate routing decisions in a condition of low visibility, low environmental familiarity, and high anxiety. However, the existing fire evacuation routing models using various algorithm such as ant colony optimization or particle swarm optimization can neither properly interpret the delay caused by congestion during evacuation nor determine the best layout of emergency exit guidance signs; thus bee colony optimization is expected to solve the problem. This study aims to develop a fire evacuation routing model "Bee-Fire" using artificial bee colony optimization (BCO) and to test the routing model through a simulation run. Bee-Fire is able to find the optimal fire evacuation routing solutions; thus not only the clearance time but also the total evacuation time can be reduced. Simulation shows that Bee-Fire could save 10.12% clearance time and 15.41% total evacuation time; thus the congestion during the evacuation process could be effectively avoided and thus the evacuation becomes more systematic and efficient
Capabilities-based forecasting model for innovation development in small-and-medium construction firms (SMCFS)
No full textTriggering innovation among Small-and-Medium Construction Firms (SMCFs) is of paramount importance to gear up the growth of construction firms. Thus, this study aims to develop a Capability-Based forecasting model for innovation development in SMCFs. Built on 157 questionnaires, the model was tested using partial least squares (PLS) technique of structural equation modelling (SEM). The practicality and robustness of this model was then validated by 12 experts. Findings affirm SMCFs making use of multiple Capability-Based approaches would be able to secure their performance via innovation activities. For academia, the new model contributes to the stream of construction innovation management by integrating both technological and organizational innovations in a single framework. For practitioners and policymakers, the model offers valuable input for continuing growth of SMCFs via innovation