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Assessment of Compressive Mechanical Behavior of Bis-GMA Polymer Using Hyperelastic Models
No full textDespite wide industrial applications of Bis-GMA polymer, very few studies are available about the material classification, mechanical properties, and behavior of this material. In this study, the compressive behavior of Bis-GMA polymer was studied using different hyperelastic constitutive models through a hybrid experimental-computational process. Standard uniaxial compression tests were conducted to extract the mechanical behavior and structural response of the Bis-GMA polymer. A nano-indentation experiment was used to verify the compressive behavior of Bis-GMA polymer in the form of hyperelastic behavior. The finite element model and real-time simulation of the test incorporating different hyperelastic models were developed in comparison with the experimental finding to obtain the proper type of hyperelastic behavior of Bis-GMA polymer. The results indicate that a second-order polynomial hyperelastic model is the best fit to predict the behavior of Bis-GMA polymer. Next, the validated model was used to determine the true stress-strain curve of the Bis-GMA polymer. © 2019 by the authors
Knowledge generation in the wake of the Fukushima Daiichi nuclear power plant disaster
No full textA disaster is a crisis situation that causes significant harm to humans, the environment, the economy, and impacts upon society’s ability to cope both during the event and with the aftermath. A disaster may escalate rapidly to reach unpredicted consequences. They can be naturally occurring, or man-made, or a combination of the two. In this study we have focused on the Fukushima Daiichi nuclear power plant accident of 2011 that subsequently unleashed a floodgate of scientific activities, including basic and applied research, technology development, policy reform, inter-disciplinary collaboration, citizen science and re-strategization of research networks. In this context, a bibliometric study has been conducted on 5455 publications on the Fukushima disaster indexed by Scopus for the 2011–2017 period. The aim is to identify key papers in the field, the most substantive contributors to the literature, and to begin to map out the emergence of a body of knowledge resulting from the disaster. The findings present main national and international collaborators on Fukushima disaster related research, as well as an indication of the major research themes evolving over the immediate years following the event. This allows for a deeper understanding of the longitudinal impact of a disaster on society and upon the international research community and its deliberations. © 2019, Akadémiai Kiadó, Budapest, Hungary
Sintering behavior of anorthite-based composite ceramics produced from natural phosphate and kaolin
No full textIn the present work anorthite-TCP composite ceramics was produced for the first time by the solid-state sintering process involving the mixture of local natural materials of phosphate and kaolin. Various samples were prepared by varying the kaolin content from 47 to 57 wt%. The composite ceramics were sintered in air at various temperatures ranging from 1250 °C to 1325 °C and characterized to determine the phase present, relative density, Vickers microhardness, chemical bonding of molecules and microstructural development. In general, all the samples exhibited a hybrid structure, comprising of anorthite and β-TCP as the major phases with a concomitant minor phases such as TTCP and/or gehlinite depending on the temperature and kaolin content. In addition, increasing kaolin content and sintering temperature were found to be effective in improving the densification and hardness of the sintered body. In particular, sample containing 57 wt% kaolin exhibited excellent densification at 1300 °C and 1325 °C, achieving above 97% dense bodies and highest hardness of about 6.5 ± 0.7 GPa. Microstructural investigation revealed that a dense structure was evident for these samples due mainly to enhanced particle coalescence during the liquid phase sintering, resulting in pore elimination and grain coarsening. © 2019 Elsevier Ltd and Techna Group S.r.l
Evaluation of Polycyclic Aromatic Hydrocarbons Contamination in the Sediments of the Johor Strait, Peninsular Malaysia
No full textIn May 2013, sediment samples were collected from five stations in the Straits of Johor, near the southern tip of Peninsular Malaysia, in order to evaluate the distribution and sources of polycyclic aromatic hydrocarbons (PAHs). The concentrations of 16 United States Environmental Protection Agency PAHs varied from 650.5 to 1441.2 ng g −1 dry weight (dw) with a mean value of 985.5 ng g −1 dw. PAHs can be classified as moderate level pollution in the collected samples. When comparing PAHs in this study with that of the sediment quality guidelines (SQGs), it was found that the total PAHs, low molecular weight (LMW), and high molecular weight (HMW) PAHs might incur minimal adverse biological effects. The diagnostic ratios of individual PAHs indicated both petrogenic and pyrogenic origins with predominantly pyrogenic sources, the findings of which are further supported by the results from principal component analysis (PCA). The PCA results reveal contributions of 44.44%, 32.3%, and 18.96% for traffic-related, coal combustion, and petroleum-related products, respectively. These findings indicate that the effective monitoring and significant improvement resulting from the implementation of environmental regulations in Malaysia might have caused a shift in the source of petroleum hydrocarbons in the Straits of Johor's aquatic ecosystems from petrogenic to pyrogenic origins. © 2017, © 2017 Taylor & Francis Group, LLC
Micropolitics of middle managers in influencing centre-led change initiative: Case Study of a Malaysian based MNC
No full textThe purpose of this article is to explore the micropolitics of middle managers in influencing the development and outcome of a centre-led change initiative. This study was empirically based on a novel context in a Malaysia based multinational company (MNC) and four of its Asian subsidiaries. This qualitative study was conducted through a multiple embedded case study approach. The findings demonstrate that middle managers have within their powers to influence the development and eventually the outcome of change. This was achieved through control of middle managers on resources such as business knowledge and networking in influencing the meaning of change itself. This article allows the authors to investigate an in-depth exploration of how subsidiary managers operate. It contributes to the change literature by expanding the knowledge about the tight coupling between power and politics of organizational sensemaking. © 2019 Penerbit Universiti Kebangsaan Malaysia. All rights reserved
Anodic and cathodic deposition of polyaniline films: a comparison between the two methods
No full textThis paper reports the comparison of polyaniline (PAni) thin films grown by anodic and cathodic electrodeposition. The growth condition, structure, optical property, thickness and morphology of the deposited layers have been characterized using cyclic voltammogram, x-ray diffraction (XRD), UV-vis spectroscopy, optical profilometry and scanning electron microscopy (SEM). The thin films grown from anodic deposition show blue-violet colour, which denotes pernigraniline fully oxidised state whereas the layers grown using cathodic deposition show pale yellow colour, which indicates leucoemeraldine fully reduced state of PAni. PAni grown from anodic deposition exhibit amorphous phase with cementing effect growth and bandgap varies from 3.90-4.08 eV. PAni layer from cathodic deposition demonstrated crystalinity based on the presence of the two XRD peaks at 2θ = 30.7° and 32.1° in the XRD pattern with random distribution of smaller grains and bandgaps in a range from 1.05 to 1.20 eV. The properties of PAni thin films electrodeposited from anodic and cathodic deposition and under a variety of deposition conditions have been compared and discussed in detail. © 2019 IOP Publishing Ltd
Charm production in charged current deep inelastic scattering at HERA
No full textCharm production in charged current deep inelastic scattering has been measured for the first time in e±p collisions, using data collected with the ZEUS detector at HERA, corresponding to an integrated luminosity of 358 pb−1. Results are presented separately for e+p and e−p scattering at a centre-of-mass energy of s = 318 GeV within a kinematic phase-space region of 200 GeV2 < Q2 < 60000 GeV2 and y < 0.9, where Q2 is the squared four-momentum transfer and y is the inelasticity. The measured cross sections of electroweak charm production are consistent with expectations from the Standard Model within the large statistical uncertainties. © 2019, The Author(s)
Effect of operational variables on biological hydrogen production from palm oil mill effluent by dark fermentation using response surface methodology
No full textThis work is a study of the performance and effect of operational parameters on biohydrogen production from palm oil mill effluent by dark fermentation in batch mode. The tests were conducted with samples prepared in 150 mL bottles using a shaker at 150 rpm. Response surface methodology was applied to investigate the influence of the four significant independent parameters viz. pH (5, 5.5, and 6), temperature (30°C, 35°C, and 40°C), substrate concentration (5,000, 12,500, and 20,000 mg L –1 ) and inoculum–substrate ratios of 2, 0.8, and 0.5 (expressed as volatile suspended solid (VSS) basis) with the inoculum concentration of 10 g L –1 VSS on biohydrogen production. All the experiments were analyzed at the incubation time of 8, 16, and 24 h. Upon seeing each interval, the results were compared. The highest chemical oxygen demand (COD) removal, the hydrogen content in the biogas as hydrogen percentage (H 2 %), and hydrogen yield (HY) were obtained 58.3%, 80%, and 3.63 mol H 2 mol –1 glucose, respectively, at 24 h incubation time. An overlay study was done to find an overall optimization of the parameters. The optimized conditions were COD removal 49%, HY 3.2 mol H 2 mol –1 glucose, and hydrogen percentage 80%. Also, the Monod model was studied to calculate the kinetics constants of the maximum substrate utilization rate (U max ) and half-velocity K s which are found to be 0.261 g L –1 d –1 and 0.349 mg L –1 , respectively. © 2019 Desalination Publications. All rights reserved
Exploring the interaction mechanism of a dicarboxamide fungicide, iprodione with bovine serum albumin
No full textAbstract: Binding of iprodione (IPR), a dicarboxamide fungicide, to the carrier protein in bovine circulation, bovine serum albumin (BSA) was characterized with the help of fluorescence, absorption, circular dichroism and Fourier transform infrared (FTIR) spectral measurements in combination with computational analysis. The increase in the KSV (Stern–Volmer constant) value with temperature and absorption spectral results characterized the IPR-induced quenching of BSA fluorescence as dynamic quenching. On the other hand, higher value (> 1011 M−1 s−1) of the bimolecular quenching rate constant (kq) suggested complex formation between IPR and BSA. In view of it, increase in KSV value with temperature can be considered as an indication of the involvement of endothermic apolar (hydrophobic) interactions in stabilizing the IPR–BSA complex, as these forces are maximized at higher temperature. A weak binding affinity was anticipated from the values of the binding constant (Ka = 0.83–2.69 × 103 M−1) for IPR–BSA association. Thermodynamic analysis of the binding data further supported contribution of hydrophobic interactions in the IPR–BSA association process. This result was validated by the computational docking analysis. Spectral results from three-dimensional fluorescence and circular dichroism demonstrated microenvironmental changes around BSA fluorophores and protein’s structural (secondary and tertiary) alterations, respectively, upon IPR binding to the protein. Slight variation in the secondary structures of BSA in the presence of IPR was also verified from FTIR spectral results. IPR was found to bind to both site I (subdomain IIA) and site II (subdomain IIIA) of BSA, showing more preference toward site II, as identified by the competitive drug displacement results and supported by the computational analysis. Graphic abstract: [Figure not available: see fulltext.]. © 2019, Institute of Chemistry, Slovak Academy of Sciences
Optimal Design of a New Cascaded Multilevel Inverter Topology With Reduced Switch Count
No full textMultilevel inverters (MLIs) are a great development for industrial and renewable energy applications due to their dominance over conventional two-level inverter with respect to size, rating of switches, filter requirement, and efficiency. A new single-phase cascaded MLI topology is suggested in this paper. The proposed MLI topology is designed with the aim of reducing the number of switches and the number of dc voltage sources with modularity while having a higher number of levels at the output. For the determination of the magnitude of dc voltage sources and a number of levels in the cascade connection, three different algorithms are proposed. The optimization of the proposed topology is aimed at achieving a higher number of levels while minimizing other parameters. A detailed comparison is made with other comparable MLI topologies to prove the superiority of the proposed structure. A selective harmonic elimination pulse width modulation technique is used to produce the pulses for the switches to achieve high-quality voltage at the output. Finally, the experimental results are provided for the basic unit with 11 levels and for cascading of two such units to achieve 71 levels at the output. © 2013 IEEE