Department of Physics

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This paper is the second in a two-part exposition on surface-directed spinodal decomposition (SDSD), i.e., the interplay of kinetics of wetting and phase separation at a surface which is wetted by one of the components of a binary mixture. In our first paper [P. Das, P. K. Jaiswal, and S. Puri, Phys. Rev. E 102, 012803 (2020)2470-004510.1103/PhysRevE.102.012803], we studied SDSD on chemically heterogeneous and physically flat substrates. In this paper, we study SDSD on a chemically homogeneous but morphologically patterned substrate. Such substrates arise in a vast variety of technological applications. Our goal is to provide a theoretical understanding of SDSD in this context. We present detailed numerical results for domain growth both inside and above the grooves in the substrate. The morphological evolution can be understood in terms of the interference of SDSD waves originating from the different surfaces comprising the substrate. © 2020 American Physical Society.

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Physical Review E

Surface-directed spinodal decomposition on morphologically patterned substrates

Here, we review some of the recent developments in quantum optics. After a brief introduction to the historical development of the subject, we discuss some of the modern aspects of quantum optics including atom field interactions, quantum state engineering, metamaterials and plasmonics, optomechanical systems, PT (parity-time) symmetry in quantum optics, as well as, quasi-probability distributions and quantum state tomography. Further, the recent developments in topological photonics is briefly discussed. The potent role of the subject in the development of our understanding of quantum physics and modern technologies is highlighted. © 2020, Indian Academy of Sciences.

Resonance

Trends in Quantum Optics: A Personal Perspective

This Article contains an error in Figure 7, in which Panel A was a duplication of Panel B. The correct Figure 7 appears below as Figure 1. (Figure presented.) Additionally, this Article contains typographical errors in the Introduction: “Alpha radiation, one form of Ionizing radiation, is a stream of doubly charged particles and is emitted from radioactive decay of a heavy nucleus, D-T or D-D reactions1.” should read: “Alpha radiation, one form of Ionizing radiation, is a stream of doubly charged particles and is emitted from radioactive decay of a heavy nucleus and D-T reaction1.” “In a neutron generator utilizing D-D to D-T reaction for emission of monoenergetic neutrons for nuclear material interrogation purpose, monitoring of alpha radiation generated in opposite to neutrons is used for associated particle imaging2.” should read: In a neutron generator utilizing D-T reaction for emission of monoenergetic neutrons for nuclear material interrogation purpose, monitoring of alpha radiation generated in opposite to neutrons is used for associated particle imaging2.” © 2020, The Author(s).

Scientific Reports

Author Correction: Efficient Alpha Radiation Detector using Low Temperature Hydrothermally Grown ZnO:Ga Nanorod Scintillator (Scientific Reports, (2019), 9, 1, (11354), 10.1038/s41598-019-47732-1)

In the present scenario of COVID-19, there has been a sudden surge in demand for tele- consultancy. Such measures require resources to support the system. Replacement of conventional equipment used in a clinic with digital equipment is not feasible due to their cost and scalability issues. The authors developed a simple low-cost (almost zero cost) method to convert a conventional stethoscope into a tele-stethoscope. Such a simple modification can be useful in periphery wherein doctors are still not available and the growing number of patients would require a diagnosis of the chest conditions.

JOURNAL OF FAMILY MEDICINE AND PRIMARY CARE

A low-cost solution for converting existing stethoscope into tele-stethoscope in resource-constrained setting for COVID-19 pandemic

This paper discusses the structural, microstructure, optical and electrical properties of perovskite CaSnO3 modified by Ti doping. Single phase of Ti-doped CaSnO3 was obtained using sol-gel method followed by calcination at 750 °C. X-ray diffraction and Fourier transform infrared spectroscopy techniques were used to probe Ti in the samples. Value of lattice parameters of all samples obtained from Rietveld refinement initially decreases with Ti-doping up to CSO5 and then slight increases for CSO7, due to difference in ionic radius between Ti4+ (0.61 Å) and Sn4+ (0.69 Å) and surface defect respectively. Using SEM, an average grain size of sintered samples was determined in the range of (0.38-1.02) μm. Because of the presence of dipole at large distances, the dielectric constant and tangent loss of samples was found to be independent of temperatures up to 300 °C, making it a potential candidate for thermally stable capacitor application. Nevertheless, the Arrhenius type conduction mechanism was found to be active in all samples with activation energy (0.41-0.68) eV, indicated that the conduction in samples occurred by transferring electrons between degenerate sites of Sn (Sn4+/Sn3+/Sn2+) and Ti (Ti4+/Ti3+/Ti2+). The P-E loop of CSO5 sample shows higher saturation polarization and coercive field than CSO0, making it a potential candidate for memory device application. © 2020 IOP Publishing Ltd.

Physica Scripta

Structural, microstructure, optical, and electrical properties of Ti-doped CaSnO3prepared by Sol-Gel chemical route

At Moriond 2019, Belle collaboration has announced new measurements on the flavour ratios (formula presented) which are consistent with their Standard Model predictions within (formula presented). After inclusion of these measurements, the global tension in (formula presented) has reduced from (formula presented) which is still significant. The measurements of these ratios indicate towards the violation of lepton flavor universality in (formula presented) decay. Assuming new physics in (formula presented) transition, we have done a global fit to all available data in this sector to identify the allowed new physics solutions. We find that there are seven allowed new physics solutions which can account for all measurements in (formula presented) transition. We show that a simultaneous measurement of the (formula presented) polarization fraction and forward-backward asymmetry in (formula presented)(formula presented), the zero crossing point of forward backward asymmetry in (formula presented) and the branching ratio of (formula presented) decay can distinguish these seven new physics solutions if they can be measured with a required precision. © Springer Nature Singapore Pte Ltd 2020.

Springer Proceedings in Physics

New physics solutions for b→ cτν Anomalies After Moriond 2019

We propose a framework to study the topological properties of an optical bound state in the continuum (BIC). Here, the formation of a BIC has been shown using the interaction between proximity resonances undergoing avoided resonance crossing in a simple fabrication, feasible gain-loss assisted microcavity. Similar to a Friedrich-Wingten (FW)-type BIC, the formation of an ultrahigh-quality (Q) mode due to the precise destructive interference between resonances has been reported. The enhancement in the Q factor was found to be more than four orders of magnitude greater than the other participating resonances. Furthermore, multiple such FW-type high-Q operating points from the same set of proximity resonances have been identified. Upon further inspection, we report the formation of a special-BIC line in the system parameter space connecting the locations of these operating points. Further, we closely investigate the light dynamics of systems near single and multiple quasi-BICs. Aiming to develop a scheme to enhance the performance of optical sensing in a microcavity, we study the sensitivity of transmission coefficients and quality factor to sense even ultrasmall perturbations in the system configuration. Our proposed scheme would open up a vast potential for an enhanced desired optical response in enhanced nonlinear applications, low-threshold nano- A nd microlasers, and device-level sensors. © 2020 American Physical Society.

Physical Review A

Ultrasensitive light confinement: Driven by multiple bound states in the continuum

Exceptional points (EPs) in non-Hermitian systems have recently attracted considerable attention owing to unique state-flipping and peculiar phase accumulation features. The dynamical encirclement of an EP and corresponding time-asymmetric mode evolution properties due to the breakdown in the adiabatic theorem have been a key to a range of exotic physical effects in various open atomic, molecular, and optical systems. Here, exploiting a new gain-loss-assisted dual-mode optical waveguide that hosts a dynamical EP-encirclement scheme, we have explored the enhanced nonreciprocal effect in the dynamics of light with the onset of saturable nonlinearity in the optical medium. We propose a prototype waveguide-based isolation scheme with the judicious tuning of nonlinearity level where one can pass only a chosen mode in any of the desired directions as per device requirement. The deliberate presence of EP enormously enhances the nonreciprocal transmission contrast even up to 40 dB over the proposed device length with a scope of further scalability. This exclusive topologically robust, mode-selective all-optical isolation scheme will certainly offer opportunities in integrated photonic circuits for efficient coupling operation from external sources and improve device performances. © 2020 American Chemical Society.

ACS Photonics

Exceptional Point and toward Mode-Selective Optical Isolation

Direct transition of trivial optical lattice to its non-trivial counterpart verified by customization of bandgap is reported. Numerical simulations show that no localization transition is observed in non-trivial lattices due to deliberate refractive-index disorder. ©2019 The Author(s).

2020 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2020 - Proceedings

Transverse Localization of light: Towards a paradigm shift from trivial to non-trivial lattice

In this communication, fenugreek β-amylase was immobilized onto functionalized tungsten disulfide nanoparticles through cross-linker glutaraldehyde and successful immobilization was confirmed by SEM, AFM and FTIR spectroscopy. To make the process economical and efficient, optimization of independent variables was carried out using Box-Behnken design of response surface methodology. Approximately similar predicted (85.6%) and experimental (84.2%) immobilization efficiency revealed that the model is suitable for design of space. Optimum temperature was calculated to be 60 °C. After immobilization, an increased Km (2.12 times) and a decreased Vmax (0.58 times), indicated inaccessibility of active site residues to the substrate. The immobilized enzyme retained 77% relative activity after 10 uses whereas 40% residual activity was obtained after 120 days. An increased half-life with concomitantly decreased kinetic rate constant revealed that the immobilized enzyme is more stable at a higher temperature and the process followed first-order kinetics (R2 &gt; 0.93). The limit of detection for maltose and sucrose fluorescence biosensor was found to be 0.052 and 0.096 mM, respectively. Thermodynamic parameters such as changes in Gibbs free energy (ΔG &lt; 0), enthalpy (ΔH &gt; 0) and entropy (ΔS &gt;0) revealed that the process is spontaneous and endothermic, driven by hydrophobic interactions. Thermo-stability data at higher temperature for the immobilized enzyme makes it a suitable candidate for industrial applications in the production of maltose in food and pharmaceutical industries. Furthermore, fluorescence biosensor could be used to detect and quantify maltose and sucrose to maintain the quality of industrial products. © 2019 Elsevier B.V.

Colloids and Surfaces B: Biointerfaces

{Immobilization of fenugreek $\beta$-amylase onto functionalized tungsten disulfide nanoparticles using response surface methodology: Its characterization and interaction with maltose {\ldots}}