Shiv Nadar University

About: Shiv Nadar University is a education organization based out in Dadri, Uttar Pradesh, India. It is known for research contribution in the topics: Population & Graphene. The organization has 1015 authors who have published 1924 publications receiving 18420 citations.

Enhanced antibacterial properties and the cellular response of stainless steel through friction stir processing

Abstract: Biofilm related bacterial infection is one of the primary causes of implant failure. Limiting bacterial adhesion and colonization of pathogenic bacteria is a challenging task in health care. Here, a highly simplistic processing technique for imparting antibacterial properties on a biomedical grade stainless steel is demonstrated. Low-temperature high strain-rate deformation achieved using submerged friction stir processing resulted in a nearly single phase ultra-fine grain structure. The processed stainless steel demonstrated improved antibacterial properties for both Gram-positive and Gram-negative bacteria, significantly impeding biofilm formation during the in vitro study. Also, the processed stainless steel showed better compatibility with human fibroblasts manifested through apparent cell spreading and proliferation. The substantial antibacterial properties of the processed steel are explained in terms of the favorable electronic characteristics of the metal-oxide and by using classical Derjaguin-Landau-Verwey-Overbeek (DLVO) and the extended DLVO (XDLVO) approach at the cell-substrate interface.

Dual Band Slot Antenna for MIMO Applications

Abstract: A MIMO antenna using dual - band planar antenna with rectangular slothas been proposed. The edge cleaving reduces the width of patch in comparison with conventional rectangular patch antenna designed at the same frequency, while its gain and radiating efficiency is noticeably improved. Measured results of the proposed antenna exhibits resonant frequency at 3.6GHz and 5.48GHz with an impedance bandwidth of 100MHz and 130MHz respectively. Further, the antenna is used as a radiating element for the design of 2-Element MIMO system.

Morphology dependent effective charge separation process in nanostructured MoS2 thin films for enhanced photodegradation behavior

Abstract: Recently 2D-layered nanostructure-based advanced coatings have proven the new advancement in the field of advanced oxidation processes. Effective charge separation is one of the key parameters to enhance the photodegradation ability of 2D-layered nanostructures. We report the cost-effective hydrothermal synthesis of MoS2 thin films on conductive ITO substrates with tunable morphology. Scanning electron microscopy (SEM) studies manifested the modulation in the morphology of MoS2 thin films and assured the presence of spherical, thread, and sheet-like nanostructures under the evolution of precursor concentration. UV-Visible absorption spectroscopy revealed the modulation in the optical absorption and effective bandgap narrowing with the changes in the surface morphology. The estimated bandgap value of MoS2 thin film samples is varied from 1.82 to 1.69 eV. PL spectroscopy and electrochemical studies display the morphology-dependent charge separation behavior and assure that the lowest recombination rate is attained by thread-like MoS2 nanostructures. Raman spectroscopy and X-ray photoelectron spectroscopy confirms the 2H phase of MoS2 thin films. MoS2 thin films with thread-like structures are found to be most efficient for sunlight-induced photodegradation activity as compared to other MoS2 samples. Threads-like MoS2 structures contained MoS2 thin-film with the highest charge transport properties decompose the 85% of 5µM of methylene blue (MB) molecules and 90.4 % of 5 µM of rhodamine B (RhB) molecule solution in 40 minutes and 80 minutes respectively of sunlight exposure. Prominent charge separation effects for enhanced photodegradation capabilities of MoS2 thin films due to distinct variations in morphology are explored precisely which have not been reported till now.

Routes to Synchronization in a pitch–plunge aeroelastic system with coupled structural and aerodynamic nonlinearities

Abstract: The present study aims to investigate the synchronization characteristics of a pitch–plunge aeroelastic system subjected to coupled structural free-play and dynamic stall-induced aerodynamic nonlinearities. The semi-empirical Leishman–Beddoes (LB) aerodynamic model is used to capture the dynamic stall phenomena at large angles-of-attack (AoA). A bifurcation analysis, considering the flow-speed as the control parameter, reveals that the free-play nonlinearity is primarily responsible for the dynamical transition in the presence of the attached flow. In this case, a pitch and plunge frequency coalescence takes place through an aperiodic to periodic signature transition. Furthermore, by tracking the flow specific variables estimated using the LB model, it is observed that the onset of the dynamic stall plays a pivotal role in the bifurcation scenario at high flow speed regimes, marking the presence of stall flutter. The framework of synchronization is used to discern the response dynamics at low speed and high speed flow regime by estimating the pitch and plunge modal frequencies and their corresponding phase components. The routes to synchronization are identified to be through phase-locking (frequency coalescence) and through suppression of the plunge mode by the dominance of pitching frequency in the regimes before and after the onset of dynamic stall, respectively. Finally, it is shown that the different synchronization routes can possibly be a useful tool to identify the presence of stall flutter oscillations in a coupled aeroelastic system.