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Effect of sodium lauryl sulphate on microstructure, corrosion resistance and microhardness of electrodeposition of Ni-Co3O4 composite coatings
No full textNi-Co3O4 composite coatings were electrodeposited on mild steel surface from a Watts-type bath in the presence of sodium lauryl sulfate (SLS). The dispersed Co3O4 particles in the presence of SLS have a greater tendency to move towards cathode and get incorporated in the coating. SLS modifies chemical composition, surface morphology and microstructure of the Ni-Co3O4 composite coating. The developed composite coating exhibits higher corrosion resistance and microhardness than the pure nickel coating. The loadings of bath solution with different concentrations of Co3O4 particles in the presence of SLS provide hydrophobic nature to the coating surface, which is much effective in enhancing the corrosion resistance of Ni-Co3O4 composite coating. The agglomeration of Co3O4 particles (>3 g/L) under high bath load condition develops defects and dislocation on the coating surface, which results in lower corrosion resistance of the deposit. The mechanical properties of the hydrophobic coatings were assessed by the linear abrasion test
Signatures of Specific DNA Binding by the AT-Rich Interaction Domain of BAF250a
No full textThe AT-rich interaction domain (ARID) containing BAF250a is a subunit of the BAF-A class of SWI/SNF chromatin remodeling complexes. The ARID belongs to a family of conserved DNA binding domains found in several eukaryotic proteins; however, its exact contribution to BAF250a function and the mechanism of its DNA binding are not well understood. Here we have probed the interaction of the BAF250a ARID with three different double-stranded DNA (dsDNA) sequences to understand its DNA binding properties. A comprehensive biophysical and thermodynamic study using nuclear magnetic resonance (NMR) spectroscopy and isothermal titration calorimetry revealed the complex nature of BAF250a ARID-DNA interactions. The thermodynamic signatures of the BAF250a ARID with 12 A-T bp dsDNA (AT-12) are distinct from those of 12 G-C bp dsDNA (GC-12) or 12 bp Dickerson dodecamer DNA (DD-12) sequences. We observed that the binding of the BAF250a ARID with AT-12 DNA is enthalpically driven in a tested temperature range of 5-25 °C. BAF250a ARID/AT-12 DNA interaction exhibited a larger negative calorimetric specific heat change (�Cp) compared to that of BAF250a ARID/GC-12 DNA or BAF250a ARID/DD-12 DNA interactions. In the presence of salt (NaCl), ARID/AT-12 DNA binding was less perturbed than ARID/GC-12 DNA or ARID/DD-12 DNA binding. Overall, these results show that BAF250a ARID/AT-12 DNA interaction has signatures of "specific" binding. Furthermore, using NMR chemical shift perturbation experiments, we have identified DNA binding residues on the BAF250a ARID and generated a data-driven HADDOCK model of the ARID/DNA complex that was further supported by mutating key lysine residues that were found to be important for DNA binding
Spray Coating of Two-Dimensional Suspended Film of Vanadium Oxide-Coated Carbon Nanotubes for Fabrication of a Large Volume Infrared Bolometer
No full textA novel spray coating and transfer method is developed for fabricating a suspended bolometer of vanadium oxide-coated multiwalled carbon nanotubes (VCNTs). A parametric study was performed to evaluate the effect of the substrate, modulation frequency, and temperature on the bolometric performance and revealed that the performance of the bolometer solely does not depend on the substrate parameter but modulation frequency and bias current as a function of temperature also play a key attribute. The TCR (temperature coefficient of resistance) of the suspended VCNT bolometer is �-0.41/K which is �486 higher than the reported suspended multiwalled CNTs at 300 K. Moreover, the suspended bolometer has a voltage responsivity of �67.42 ± 5.46 V/W (�7.68 times that of unsuspended) at 200 K. Thus, the study presents an efficient method to develop the suspended bolometer that has not been realized so far to obtain much higher TCR and responsivity. © 2019 American Chemical Society
On the role of four-wave mixing effect in the interactions between nonlinear modes of coupled generalized nonlinear Schrödinger equation
No full textIn this paper, we investigate the effect of four-wave mixing in the interactions among nonlinear waves such as solitons, breathers, and rogue waves of a coupled generalized nonlinear Schrödinger equation. We explore several interesting results including superposition of breather pulses, increment in the number of breather pulses and in amplitudes of breathers, and rogue waves. By strengthening the four-wave mixing parameter, we observe different transformations that occur between different localized structures. For instance, we visualize a transformation from bright soliton to breather form, bright and dark rogue wave to four-petaled rogue wave structures, four-petaled rogue wave to other rogue wave forms, and so on. Another important observation that we report here is that the interaction of a bright soliton with a rogue wave in the presence of the four-wave mixing effect provides interaction between a dark oscillatory soliton and a rogue wave
A fast polynomial chaos expansion for uncertainty quantification in stochastic electromagnetic problems
No full textVariations in material properties, boundary conditions, or the geometry can be expected in most electromagnetic problems. When these uncertainties in different regions of the model space are considered simultaneously, the stochastic dimensionality and the computational cost increase. Hence, uncertainty quantification in such problems is seldom attempted even though its quantification leads to a robust model. In this letter, a nonintrusive least square polynomial chaos expansion method is employed to quantify uncertainty due to stochastic variation of material properties. Using this method, the deviation from the mean performance for the transmission coefficient is obtained across the operational frequency range. The results compare well with Monte Carlo method and require just 1 of its total computational time
Trend Statistics Network and Channel invariant EEG Network for sleep arousal study
No full textSleep is a very important part of life. Lack of sleep or sleep disorder can cause a negative impact on day to day life and can have long term serious consequences. In this work, we propose an end-to-end trainable neural network for automated sleep arousal scoring. The network consists of two main parts. Firstly, a trend statistics network computes the moving average of the filtered signals at different scales. Secondly, we propose a channel invariant EEG network to detect the arousals in any Electroencephalography (EEG) channel. Finally, we combine the features from various channels through a convolution network and a bi-directional long short-term memory to predict the probability of arousal. Further, we propose an objective function that uses only respiratory effort related arousal (RERA) and non-arousal regions to optimize the network. We also propose a method to estimate the respiratory disturbance index (RDI) from the probability predicted by the network. Evaluation on Physionet Challenge 2018 database shows that the proposed method detects RERA with mean area under the precision-recall curve (AUPRC) of 0.50 in a 10-fold cross validation setup. The mean absolute error of RDI prediction is 6.11, while a two-class RDI severity prediction yields a specificity of 75 and a sensitivity of 83.
Monsoon mission a targeted activity to improve monsoon prediction across scales
No full textThe Monsoon Mission is a national program that has nurtured a system to provide skillful Indian summer monsoon predictions, benefiting society and advancing global science
Recent advances in thermodynamics and nucleation of gas hydrates using molecular modeling
No full textMolecular modeling and simulations have provided valuable insights into our understanding of science of gas hydrates. In this article, we review the role played by molecular modeling towards advancing our knowledge of gas hydrate systems, with specific focus on thermodynamics and nucleation. We highlight the key recent advances achieved through computational research that have led to (i) substantial improvement in the accuracy of the thermodynamic theory and (ii) elucidation of molecular mechanisms involved in the nucleation of gas hydrates. © 201
Optomechanical platform with a three-dimensional waveguide cavity
No full textAt low temperatures, microwave cavities are often preferred for the readout and control of a variety of systems. In this paper, we present design and measurements on an optomechanical device based on a three-dimensional rectangular waveguide cavity. We show that by suitably modifying the electromagnetic field corresponding to the fundamental mode of the cavity, the equivalent circuit capacitance can be reduced to 29 fF. By coupling a mechanical resonator to the modified electromagnetic mode of the cavity, we achieve a capacitance participation ratio of 43. We demonstrate an optomechanical cooperativity, C� 40, characterized by performing measurements in the optomechanically induced absorption limit. In addition, due to a low-impedance environment between the two halves of the cavity, our design has the flexibility of incorporating a dc bias across the mechanical resonator, often a desired feature in tunable optomechanical devices. © 2019 American Physical Society
Convergence analysis of finite element method for a parabolic obstacle problem
No full textA conforming finite element method is proposed and analyzed for numerical approximation of the solution of a parabolic variational inequality of the obstacle problem. The model problem, which is originally proposed using a general obstacle, is reframed as a model problem with zero obstacle but with non-homogeneous Dirichlet boundary conditions. Subsequently the discrete problem is reframed and the error analysis proving the convergence of the method is performed. The analysis requires a positive preserving interpolation with non-homogeneous Dirichlet boundary condition and a post-processed solution that satisfies the boundary conditions sharply. The results in the article extend the results of (Johnson, SINUM, 1976) for a zero obstacle function to a more general obstacle function