Experimental and simulated study of electrical behaviour of ZnO film deposited on Al substrate for device applications

In this paper, zinc oxide (ZnO) film has been deposited on Al substrate by chemical wet and dry technique which is just a simple modified version of the dip coating method. In this method, it is possible to precisely control the immersion and withdrawal speed, with drying as well as annealing at the same time. The polycrystalline nature of ZnO has been confirmed by X-ray diffraction (XRD) analysis. The XRD analysis clearly indicates that some percentage of Al diffuses into the ZnO matrix at its interface region; hence it affects mobility of the sample. Hall measurement indicates the ZnO semiconductor as n-type. I–V characteristic of the sample shows that the contact is Ohmic and it can be used as a sensor at low potential value. The mobility decreases with increase in temperature. The simulation study carried out for I–V and mobility through simulation using ATLAS (SILVACO) software confirms that the experimental and simulation results are in close agreement with respect to the I–V characteristic and the mobility.     

Structural basis for ligand recognition at the benzodiazepine binding site of GABAA alpha 3 receptor, and pharmacophore-based virtual screening approach

Given the heterogeneity of GABA(A) receptor, the pharmacological significance of identifying subtype selective modulators is increasingly being recognized. Thus, drugs selective for GABA(A) alpha(3) receptors are expected to display fewer side effects than the drugs presently in clinical use. Hence we carried out 3D QSAR (three-dimensional quantitative structure-activity relationship) studies on a series of novel GABA(A) alpha(3) subtype selective modulators to gain more insight into subtype affinity. To identify the 3D functional attributes required for subtype selectivity, a chemical feature-based pharmacophore, primarily based on selective ligands representing diverse structural classes was generated. The obtained pseudo receptor model of the benzodiazepine binding site revealed a binding mode akin to "Message-Address" concept. Scaffold hopping was carried out across multi-conformational May Bridge database for the identification of novel chemotypes. Further a focused data reduction approach was employed to choose a subset of enriched compounds based on "Drug likeness" and "Similarity-based" methods. These results taken together could provide impetus for rational design and optimization of more selective and high affinity leads with a potential to have decreased adverse effects.     

Experimental Investigation of Flow Past a Square Cylinder at an Angle of Incidence

Flow past a square cylinder placed at an angle to the incoming flow is experimentally investigated using particle image velocimetry, hot wire anemometry, and flow visualization. The Reynolds number based on cylinder size and the average incoming velocity is set equal to 410. Data for four cylinder orientations (θ = 0, 22.5, 30, and 45°) and two aspect ratios [AR = 16 and 28] are reported. Results are presented in terms of drag coefficient, Strouhal number, time averaged velocity, stream traces, turbulence intensity, power spectra, and vorticity field. In addition, flow visualization images in the near wake of the cylinder are discussed. The shape and size of the recirculation bubble downstream of the cylinder are strong functions of orientation. A minimum in drag coefficient and maximum in Strouhal number is observed at a cylinder orientation of 22.5°. The v-velocity profile and time-average stream traces show that the wake and the separation process are asymmetric at orientations of 22.5 and 30°. The corresponding power spectra show additional peaks related to secondary vortical structures that arise from nonlinear interaction between the Karman vortices. The flow visualization images show the streamwise separation distance between the alternating vortices to be a function of cylinder orientation. Further, the flow approaches three dimensionality early, i.e., closer to the cylinder surface for the 22.5° orientation. The drag coefficient decreases with an increase in aspect ratio, while the Strouhal number is seen to increase with aspect ratio. The turbulence intensity is higher for the large aspect ratio cylinder and the maximum turbulence intensity appears at an earlier streamwise location. The overall dependence of drag coefficient and Strouhal number on orientation is preserved for the two aspect ratios studied.     

A comparative study on mechanical properties of ultrafine-grained Al 6061 and Al 6063 alloys processed by cryorolling

The present work has been focused to investigate the mechanical behavior and microstructural characteristics of cryorolled Al 6063 and Al 6061 alloys. Hardness and tensile tests of the cryorolled Al alloys were carried out to understand its deformation behavior. SEM/EBSD was used to characterise the microstructures of cryorolled Al alloys and observed the formation of ultrafine-grained microstructures in the materials due to severe plastic strain induced during cryorolling. XRD was used to analyse the formation of different phases during cryorolling of the Al alloys. It is evident from the present study that UFG Al alloys exhibit higher hardness and strength when compared to the bulk Al alloys due to the grain size, higher dislocation density and precipitation hardening effect. The cryorolled Al 6061 alloys exhibit higher tensile strength (346 MPa) and hardness (120 H_v) as compared to Al 6063 alloys (Tensile strength: 240MPa and Hardness: 96.5 H_v) in the present investigation. The deformation mechanisms of UFG Al alloys contributing to their enhanced strength are discussed.     

Mulberry non-engineered silk gland protein vis-à-vis silk cocoon protein engineered by silkworms as biomaterial matrices

Silk fibroin from silk gland of Bombyx mori 5th instar larvae was utilized to fabricate films, which may find possible applications as two-dimensional matrices for tissue engineering. Bombyx mori cocoon fibroin is well characterized as potential biomaterial by virtue of its good mechanical strength, water stability, thermal properties, surface roughness and biocompatibility. The present study aims to characterize the biophysical, thermal, mechanical, rheological, swelling properties along with spectroscopic analysis, surface morphology and biocompatibility of the silk gland fibroin films compared with cocoon fibroin. Fibroin solutions showed increased turbidity and shear thinning at higher concentration. The films after methanol treatment swelled moderately and were less hydrophilic compared to the untreated. The spectroscopic analysis of the films illustrated the presence of various amide peaks and conformational transition from random coil to beta sheet on methanol treatment. X-ray diffraction studies also confirmed the secondary structure. Thermogravimetric analysis showed distinct weight loss of the films. The films were mechanically stronger and AFM studies showed surfaces were rougher on methanol treatment. The matrices were biocompatible and supported L929 mouse fibroblast cell growth and proliferation. The results substantiate the silk gland fibroin films as potential biomaterial matrices.     

On properties of state variable stabilizing feedback of a special kind for linear time-invariant regulators

Some interesting properties of a limiting case of linear optimal regulators with quadratic performance index and prescribed degree of stability are discussed. A series of LSVF control laws may be generated by varying a scalar parameter α which specifies the minimum modulus of the real part of the closed-loop poles. All such control laws guarantee a minimum amount of phase and gain margins but differ in speed of error recovery. Explicit algebraic relations for computing feedback laws and Nyquist plots are provided for single inputn-order systems.     

Effect of Reaction Parameters on γ-AlON Formation from Al2O3 and AlN

The formation of γ-AlON from Al₂O₃ and AlN was investigated as a function of some of the reaction parameters, that is, temperature and time. The appearance of phases was followed in conjunction with the change in lattice parameter to reveal the reaction sequences of formation. An oxygen-rich γ-AlON phase formed first, which reacted further with AlN. Nitrogen diffusion through the γ-AlON lattice seemed to be rate controlling.     

A hybrid backtracking search algorithm with wavelet mutation-based nonlinear system identification of Hammerstein models

In this paper a novel and accurate approach is presented to identify varieties of nonlinear Hammerstein models (closed loop and open loop) with the help of an optimization algorithm that combines a recently proposed backtracking search algorithm with wavelet theory-based mutation scheme (BSA-WM). The optimum output MSE associated with each plant along with its statistical information justifies the better precision and accuracy of BSA-WM-based identification approach as compared to the other methods reported in earlier literature.     

Incorporating quantitative reliability engineering measures into tradespace exploration

Recently, tradespace analysis and exploration has emerged as an important focus area within the Department of Defense Engineered Resilient System initiative, which draws upon engineering concepts, science, and design tools to produce trusted and effective solutions for a wide range of operational contexts. Most of the previous research on tradespace analysis, including those developed for rotorcraft, emphasize performance. However, non-functional requirements such as reliability, availability, and maintainability have received minimal consideration, despite their direct influence on program level concerns such as operation and support as well as affordability. This paper proposes a strategy to incorporate reliability engineering into tradespace analysis. We also develop a subsystem-level reliability investment model that is illustrated through a simplified example. Our results suggest that reliability investment could achieve significant savings over a systems lifecycle, thereby enabling improved fleet availability and a larger fleet size.