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On the orientation relationships in phase transformation of CaTiO3
No full textElectron Backscattering Diffraction (EBSD) is a well-known technique which is primarily used to analyse the microstructural features in metallic materials, including the orientation relationship between microstructural constituents. However, its versatility has not yet been critically utilized to establish crystallographic relationships involved in phase transformation of ceramics. In view of the significance of transformation twinning in ceramics on mechanical properties, the representative orientation relationships in twinned grains of CaTiO3 is investigated using EBSD. It is observed that the matrix/twin pairs of CaTiO3 have misorientation angles at 87 degrees, 90 degrees and 98 degrees. The misorientations associated with the boundaries between twin/twin pairs formed by different twinning orientation relationships are noted at 90 degrees, 91 degrees, 92 degrees and 98 degrees. On the basis of the orientation relationships, the crystallography of cubic to orthorhombic and tetragonal to orthorhombic phase transformations in CaTiO3 is explored. The most favorable orientation relationships pertaining to such a phase transformation are (001)(0)100](0)parallel to(03 (1) over bar)(c)(3) over bar 13](c) between parent cubic and daughter orthorhombic phases and (001)(0)100](0)parallel to(1 (1) over bar(2) over bar)(t)(8) over bar(2) over bar(3) over bar](t) between parent tetragonal and daughter orthorhombic phases of CaTiO3
Search for an L-mu - L-tau gauge boson using Z -> 4 mu events in proton-proton collisions at root s=13 TeV
No full textA search for a narrow Z' gauge boson with a mass between 5 and 70 GeV resulting from an L-mu - L-tau U (1) local gauge symmetry is reported. Theories that predict such a particle have been proposed as an explanation of various experimental discrepancies, including the lack of a dark matter signal in direct-detection experiments, tension in the measurement of the anomalous magnetic moment of the muon, and reports of possible lepton flavor universality violation in B meson decays. A data sample of proton-proton collisions at a center-of-mass energy of 13 TeV is used, corresponding to an integrated luminosity of 77.3 fb(-1) recorded in 2016 and 2017 by the CMS detector at the LHC. Events containing four muons with an invariant mass near the standard model Z boson mass are analyzed, and the selection is further optimized to be sensitive to the events that may contain Z -> Z'mu mu -> 4 mu decays. The event yields are consistent with the standard model predictions. Upper limits of 10(-8)-10(-7) at 95% confidence level are set on the product of branching fractions B(Z -> Z'mu mu)B(Z' -> mu mu), depending on the Z' mass, which excludes a Z' boson coupling strength to muons above 0.004-0.3. These are the first dedicated limits on L-mu - L-tau models at the LHC and result in a significant increase in the excluded model parameter space. The results of this search may also be used to constrain the coupling strength of any light Z' gauge boson to muons. (C) 2019 The Author(s). Published by Elsevier B.V
Imaging flow distribution through nanoporous polymer films using bright-field nanoscopy
No full textBright-field nanoscopy (BFN), an optical visualization technique using standard diffraction-limited microscopy, has been used in the past to visualize nanoscale objects such as grain boundaries in single layer graphene and water transport across nanomembranes. Here, we show how BFN can be used to visualize and gather information about water transport networks in porous polymer membranes. We were able to visualize a sub-100 nm network of pores in a polyelectrolyte multilayer using this technique. The extracted pore diameter distribution fitted well to an exponential distribution. Further, the time evolution of pore diameter displayed two distinct regimes consistent with expectations. Published under license by AIP Publishing
Low-cost VO2(M1) thin films synthesized by ultrasonic nebulized spray pyrolysis of an aqueous combustion mixture for IR photodetection
No full textWe report detailed structural, electrical transport and IR photoresponse properties of large area VO2(M1) thin films deposited by a simple cost-effective two-step technique. Phase purity was confirmed by XRD and Raman spectroscopy studies. The high quality of the films was further established by a phase change from low temperature monoclinic phase to high temperature tetragonal rutile phase at 68 degrees C from temperature dependent Raman studies. An optical band gap of 0.75 eV was estimated from UV-visible spectroscopy. FTIR studies showed 60% reflectance change at = 7.7 m from low reflectivity at low temperature to high reflectivity at high temperature in a transition temperature of 68 degrees C. Electrical characterization showed a first order transition of the films with a resistance change of four orders of magnitude and TCR of -3.3% K-1 at 30 degrees C. Hall-effect measurements revealed the n-type nature of VO2 thin films with room temperature Hall mobility, (e) of 0.097 cm(2) V-1 s(-1), conductivity, sigma of 0.102 (-1) cm(-1) and carrier concentration, n(e) = 5.36 x 10(17) cm(-3). In addition, we fabricated a high photoresponsive IR photodetector based on VO2(M1) thin films with excellent stability and reproducibility in ambient conditions using a low-cost method. The VO2(M1) photodetector exhibited high sensitivity, responsivity, quantum efficiency, detectivity and photoconductive gain of 5.18%, 1.54 mA W-1, 0.18%, 3.53 x 10(10) jones and 9.99 x 10(3) respectively upon illumination with a 1064 nm laser at a power density of 200 mW cm(-2) and 10 V bias voltage at room temperature
Conductivity inversion of ZnO nanoparticles in ZnO-carbon nanofiber hybrid thin film devices by surfactant-assisted C-doping and non-rectifying, non-linear electrical properties via interfacial trap-induced tunneling for stress-grading applications
No full textA special nonrectifying, nonlinear current-voltage characteristic is observed in ZnO nanoparticle-anchored carbon nanofiber (ZnO-CNF) hybrid thin film devices, which has interesting applications in nonlinear stress-grading materials for high-voltage devices and overvoltage protectors in multifunctional electronic circuits. A simple chemical precipitation method is used to fabricate the hybrid films, followed by vacuum annealing at elevated temperatures. Interestingly, the organic surfactant (Triton X-114), used as a binder during the film deposition, manifests unintentional carbon doping into a ZnO lattice, which leads to a conductivity inversion of ZnO from n-type in the lower temperature (300 degrees C) annealed hybrid into p-type in the higher temperature (600 degrees C) annealed film. Electrical characterizations reveal that the CNF-ZnO interfaces act as a metal-semiconductor junction with low barrier height, leading to nonrectifying junction properties. Also, the surfactant-induced C-atoms create trap states at the interface which ``emit'' the trapped charges via interfacial field-assisted tunneling, thus imposing nonlinearity (in both forward and reverse directions) on the I-V curves
Solubilities of dialkylhydrogen phosphonates in supercritical carbon dioxide and their correlation using semi-empirical equations
No full textThe solubilities of dibutylhydrogen phosphonate (DBHP) and dihexylhydrogen phosphonate (DHHP) in supercritical carbon dioxide were determined at 313-333 K and 10-20 MPa. The mole fraction solubility of DBHP and DHHP are in the range of 3.4 x 10(-4) to 66.4 x 10(-4) and 4.5 x 10(-4) to 806.6 x 10(-4,) respectively. The solubility data are self-consistent with Mendez-Teja model. The experimental solubilities were correlated using Chrastil, Hezave-Lashkarbolooki and three models based on activity coefficient models. Hezave-Lashkarbolooki model resulted in better solubility predictions for DBHP with an AARD of 5%. Chrastil and van Laar activity coefficient based model correlated the solubility of DHHP with a lowest AARD of 11%
Mutational pathway maps and founder effects define the within-host spectrum of hepatitis C virus mutants resistant to drugs
No full textKnowledge of the within-host frequencies of resistance-associated amino acid variants (RAVs) is important to the identification of optimal drug combinations for the treatment of hepatitis C virus (HCV) infection. Multiple RAVs may exist in infected individuals, often below detection limits, at any resistance locus, defining the diversity of accessible resistance pathways. We developed a multiscale mathematical model to estimate the pre-treatment frequencies of the entire spectrum of mutants at chosen loci. Using a codon-level description of amino acids, we performed stochastic simulations of intracellular dynamics with every possible nucleotide variant as the infecting strain and estimated the relative infectivity of each variant and the resulting distribution of variants produced. We employed these quantities in a deterministic multi-strain model of extracellular dynamics and estimated mutant frequencies. Our predictions captured database frequencies of the RAV R155K, resistant to NS3/4A protease inhibitors, presenting a successful test of our formalism. We found that mutational pathway maps, interconnecting all viable mutants, and strong founder effects determined the mutant spectrum. The spectra were vastly different for HCV genotypes 1a and 1b, underlying their differential responses to drugs. Using a fitness landscape determined recently, we estimated that 13 amino acid variants, encoded by 44 codons, exist at the residue 93 of the NS5A protein, illustrating the massive diversity of accessible resistance pathways at specific loci. Accounting for this diversity, which our model enables, would help optimize drug combinations. Our model may be applied to describe the within-host evolution of other flaviviruses and inform vaccine design strategies. Author summary The spectrum of viral mutants that exists in infected individuals defines the diversity of drug resistance pathways accessible to any virus. Drug combinations that block these pathways the most effectively are likely to elicit the best responses. The mutants may lie below detection, rendering treatment optimization difficult. We constructed a multiscale mathematical model to estimate the pre-treatment frequencies of the entire spectrum of hepatitis C virus mutants at specific resistance loci. We described intracellular evolution stochastically and extracellular dynamics deterministically, gaining accuracy without escalating computational costs. Model predictions quantitatively captured experimental observations, explained confounding inter-subtype differences, and unraveled the massive diversity of accessible resistance pathways. Our study would help describe viral evolution more accurately, optimize drug treatments and design vaccines
Subcell Modeling of Partially Shaded Photovoltaic Modules
No full textIncreased photovoltaic installations in densely built-up areas give rise to non-uniform irradiation causing partial shading. Non-uniform irradiation further leads to non-uniform temperature, leading to a reduction in output and the formation of deteriorating hotspots. A detailed model involving subcell level behavior is pivotal in understanding the impact of partial shading. In this paper, such a model is developed that analyzes the output of photovoltaic (PV) modules under different translucent and opaque shades while incorporating the diffused light effects. This model further includes the temperature variation of the module and also captures the bypass diode characteristics. The proposed model is experimentally validated for horizontal, vertical, slant, and patch shading patterns with varying shading intensities. This subcell model is shown to perform better than four existing methods of partial shading output prediction. It improves the output open-circuit voltage and short-circuit current prediction accuracy by more than 10% when compared with the average irradiance-based modeling approach, which is the best among the existing methods. Overall, an output prediction accuracy of more than 93% is achieved for opaque shading and more than 95% for translucent shading. As this paper provides the output of PV modules under partial shading, it finds direct application in partial shading detection, prevention of hotspots, and global maximum power point tracking, thereby enhancing their life and efficiency
Application of Multi-Stage Homotopy Analysis Method for Power System Dynamic Simulations
No full textHomotopy analysismethod (HAM) is a popular semi-analytical method used widely in applied sciences. It stands out from the rest of the semi-analytical methods as it provides a family of solutions to nonlinear equations, including ordinary differential equations (ODEs), partial differential equations, etc. The convergence characteristics of the solutions can be varied by changing an auxiliary parameter ((h) over bar) in HAM. The convergence region of solution of ODEs using HAM can be improved by applying it over multiple intervals of time, which is referred to as multi-stage HAM (MHAM). In this paper, MHAM models for the IEEE Model 2.2 synchronous machine, IEEE Type-1 excitation system, first-order governor and first-order turbine models have been developed. The applicability of MHAM for power system dynamic simulations has been investigated in this paper using seven widely used test systems ranging from 10 generators 39 bus systems to 4092 generators 13 659 bus systems. The effect of number of terms, (h) over bar and the time step on the accuracy and stability of the solution has been studied. The effectiveness of MHAM has been compared with the modified Euler (ME) and midpoint Trapezoidal (TrapZ) methods. The accuracy of MHAM has been found to be comparable with ME and TrapZ methods for the values of (h) over bar between -1.05 and -0.95. The best accuracy is obtained for (h) over bar = -1.0, which is a special case of MHAM called multi-stage homotopy perturbation method (MHPM). In this paper, it is also shown that MHPM is equivalent to multi-stage adomian decomposition method, which has been recently explored for large power system simulations
Geotechnical considerations for the concept of coastal reservoir at Mangaluru to impound the flood waters of Netravati River
No full textThis paper explores the geotechnical feasibility for constructing coastal reservoir in Arabian Sea off Mangaluru coast. This envisages storing fresh water in a reservoir along the coast by building a sea dike to impound the flood waters of Netravati River. On one side, the dike will ensure the required quantity of freshwater flow from Netravati River to the reservoir without being drained to the sea. On the other side, the sea dike will prevent seawater from entering the reservoir, avoiding the salt contamination of the freshwater supply. Present study presents detailed investigation of the soil profiles of surrounding region of Mangaluru to explore the site condition at off Ullal beach. Lithological data on the Netravati estuary were also presented with key observation on the soil profiles in the area proposed for location of coastal reservoirs. The key finding of the study is that the region offshore of Ullal is devoid of sand and is comprised mainly of soft Silty clays. Lithological data of nine foundations at Netravati Bridge near Ullal are also presented in this paper. Based on the findings of geotechnical investigations, the paper concludes that construction of sea dike in Arabian Sea off Mangaluru coast is feasible