A cosmological study in massive gravity theory

A detailed study of the various cosmological aspects in massive gravity theory has been presented in the present work. For the homogeneous and isotropic FLRW model, the deceleration parameter has been evaluated, and, it has been examined whether there is any transition from deceleration to acceleration in recent past, or not. With the proper choice of the free parameters, it has been shown that the massive gravity theory is equivalent to Einstein gravity with a modified Newtonian gravitational constant together with a negative cosmological constant. Also, in this context, it has been examined whether the emergent scenario is possible, or not, in massive gravity theory. Finally, we have done a cosmographic analysis in massive gravity theory.     

Coulomb screening in graphene with topological defects

We analyze the screening of an external Coulomb charge in gapless graphene cone, which is taken as a prototype of a topological defect. In the subcritical regime, the induced charge is calculated using both the Green’s function and the Friedel sum rule. The dependence of the polarization charge on the Coulomb strength obtained from the Green’s function clearly shows the effect of the conical defect and indicates that the critical charge itself depends on the sample topology. Similar analysis using the Friedel sum rule indicates that the two results agree for low values of the Coulomb charge but differ for the higher strengths, especially in the presence of the conical defect. For a given subcritical charge, the transport cross-section has a higher value in the presence of the conical defect. In the supercritical regime we show that the coefficient of the power law tail of polarization charge density can be expressed as a summation of functions which vary log periodically with the distance from the Coulomb impurity. The period of variation depends on the conical defect. In the presence of the conical defect, the Fano resonances begin to appear in the transport cross-section for a lower value of the Coulomb charge. For both sub and supercritical regime we derive the dependence of LDOS on the conical defect. The effects of generalized boundary condition on the physical observables are also discussed.     

Optimization of ultrasound-assisted extraction of phenolic compounds from Sesamum indicum

Abstract

Effective extraction of phyto-biomolecules insures retaining maximum functionality along with higher recovery. In this study, ultrasound-solvent assisted extraction (USAE) was employed for optimal extraction of phyto-biomolecules from Sesamum indicum (sesame) leaves using the approach of Response Surface Methodology (RSM). The optimized condition of 200?W power, 59% methanol concentration with 1:14?g/mL solid–liquid ratio and 15?min of extraction time yielded 367.39?±?1.85?mg GAE/100?g of total phenolic content, 96.72?±?3.27% of free radical scavenging activity and 81.20?±?2.87% of iron chelating activity respectively. The extract consist of essential phytocomponents like gallic acid, chlorogenic acid, and quercetin with lipid peroxidation activities of >50% over incubation time of 48?h. Also, showed antimicrobial activity against various Gram’s negative and positive food borne pathogens. The results of this study implied the importance of USAE for effective and optimum recovery of phyto-biomolecules from Sesame leaves with retained functional properties.     

A Low‐Temperature Molecular Precursor Approach to Copper‐Based Nano‐Sized Digenite Mineral for Efficient Electrocatalytic Oxygen Evolution Reaction

In the urge of designing noble metal‐free and sustainable electrocatalysts for oxygen evolution reaction (OER), herein, a mineral Digenite Cu₉S₅ has been prepared from a molecular copper(I) precursor, [{(PyHS)₂Cu^I(PyHS)}₂](OTf)₂ ( 1 ), and utilized as an anode material in electrocatalytic OER for the first time. A hot injection of 1 yielded a pure phase and highly crystalline Cu₉S₅, which was then electrophoretically deposited (EPD) on a highly conducting nickel foam (NF) substrate. When assessed as an electrode for OER, the Cu₉S₅/NF displayed an overpotential of merely 298±3 mV at a current density of 10 mA cm^?2 in alkaline media. The overpotential recorded here supersedes the value obtained for the best reported Cu‐based as well as the benchmark precious‐metal‐based RuO₂ and IrO₂ electrocatalysts. In addition, the choronoamperometric OER indicated the superior stability of Cu₉S₅/NF, rendering its suitability as the sustainable anode material for practical feasibility. The excellent catalytic activity of Cu₉S₅ can be attributed to the formation of a crystalline CuO overlayer on the conductive Cu₉S₅ that behaves as active species to facilitate OER. This study delivers a distinct molecular precursor approach to produce highly active copper‐based catalysts that could be used as an efficient and durable OER electro(pre)catalysts relying on non‐precious metals.     

Three Bis‐BODIPY Analogous Diruthenium Redox Series: Characterization and Electronic Structure Analysis

The dianion derived from (2Z,6Z)‐3,7‐diphenyl‐N2,N6‐di(pyridin‐2‐yl)pyrrolo[2,3‐f]indole‐2,6(1H,5H)‐diimine (H₂BL), a modified BODIPY ligand precursor, is shown to be capable of bridging two metal complex fragments RuL₂, L=2,4‐pentanedionato (acac^?), 2,2’‐bipyridine (bpy) or 2‐phenylazopyridine (pap) in [Ru(acac)₂Ru(μ‐BL)Ru(acac)₂] ( 1 / 2 ), [Ru(bpy)₂Ru(μ‐BL)Ru(bpy)₂](ClO₄)₂ ([ 3 ](ClO₄)₂) and [Ru(pap)₂Ru(μ‐BL)Ru(pap)₂](ClO₄)₂ ([ 4 ](ClO₄)₂). The compounds, including a diastereoisomeric pair 1 (meso) and 2 (rac) were spectroscopically and structurally characterized. Reversible electron transfers as revealed by cyclic and differential pulse voltammetry allowed for an EPR and UV‐vis‐NIR spectroelectrochemical investigation of several neighboring charge states. Together with susceptibility measurements and TD‐DFT calculations the assignment of oxidation states reveals that 1 , 2 are diruthenium(III) species which can be oxidized or reduced by one electron whereas 3 ²⁺ and 4 ²⁺ contain ruthenium(II) and get reduced or oxidized mainly at the dianionic bridge ( 3 ²⁺) or are reduced at the ancillary ligands pap ( 4 ²⁺).     

Methods and concerns in disposal of nuclear waste from storage vials post recovery

Journal of Radioanalytical and Nuclear Chemistry - The speciation of iodine in environment must be known in order to properly assess its geological fate and to study potential remediation materials...     

VEGFR-2 targeted cellular delivery of doxorubicin by gold nanoparticles for potential antiangiogenic therapy

We report a novel gold nanobioconjugate system that achieves targeted delivery of the small molecule drug doxorubicin to endothelial cells using anti-VEGFR-2 antibody conjugated gold nanoparticles (GNPs). The reported nanobioconjugate system combines the inherent ability of GNPs to undergo high levels of derivatization with the precision of antibody recognition of a cell surface antigen. Transmission electron microscopy (TEM) and surface-enhanced Raman spectroscopy (SERS) confirmed intracellular presence of the GNPs. Using a VEGFR-2 expressing cell line and a cell line that is negative for the receptor, in combination with competition assay we established the cell specific targeted delivery of the nanobioconjugate. The nanobioconjugate system described here may have potential drug delivery applications for antiangiogenic cancer therapy.     

Leading-Order Dynamics of Gravity-Driven Flows in?Free-Standing Soap Films

We derive the leading-order equations that govern the dynamics of the flow in a falling, free-standing soap film. Starting with the incompressible Navier?CStokes equations, we carry out an asymptotic analysis using parameters that correspond to a common experimental setup. We account for the effects of inertia, surface elasticity, pressure, viscous stresses, gravity, and air drag. We find that the dynamics of the flow is dominated by the effects of inertia, surface elasticity, gravity, and air drag. We solve the leading-order equations to compute the steady-state profiles of velocity, thickness, and pressure in an experiment in which the film is in the Marangoni elasticity regime. The computational results, which include a Marangoni shock, are in good accord with the experimental measurements.     

An analytical homogenization method for heterogeneous porous materials

The objective of this work is to develop an analytical homogenization method to estimate the effective mechanical properties of fluid-filled porous media with periodic microstructure. The method is based on the equivalent inclusion concept of homogenization applied earlier for solid–solid mixture. It is assumed that porous media are described by the poroelastic constitutive law developed by Biot where porosity is a material parameter. By solving the governing equations of poroelasticity in Fourier transformed domain, the relation between periodic strain and eigenstrain in porous media is established. This relation is subsequently used in an average consistency condition involving both solid and fluid phase stresses and strains. The geometry of the porous microstructure is captured in the g-integral. This homogenization method can also be applied to estimate the equivalent properties of solid–fluid mixture where a pure solid and fluid can be modeled by assuming very low and high porosity, respectively. Several examples are considered to establish this new method by comparing with other existing analytical and numerical methods of homogenization. As an application, poroelastic properties of cortical bone fibril are estimated and compared with previously computed values.     

Optimal control of harvest and bifurcation of a prey-predator model with stage structure

This paper describes a prey-predator model with stage structure for prey. The adult prey and predator populations are harvested in the proposed system. The dynamic behavior of the model system is discussed. It is observed that singularity induced bifurcation phenomenon is appeared when variation of the economic interest of harvesting is taken into account. State feedback controller is incorporated to stabilize the model system in case of positive economic interest. Harvesting of prey and predator population are used as controls to develop a dynamic framework to investigate the optimal utilization of the resource, sustainability properties of the stock and the resource rent earned from the resource. The Pontryagin’s maximum principle is used to characterize the optimal controls. The optimality system is derived and then solved numerically using an iterative method with Runge-Kutta fourth order scheme. Simulation results show that the optimal control scheme can achieve sustainable ecosystem.