Open defecation, improper disposal of sewer line wastes and mismanagement of infectious biomedical wastes may cause severe biological contamination to the water reservoirs. On the other hand, high demand of drinking water has become again a challenge in terms of maintaining hygiene, safe and cleanliness. Nano-technological approaches can play significant roles in the efficient and effective disinfection of drinking water for the continuously growing world’s population without generating toxic byproducts. Non-conventional water disinfection process (or microbial inactivation) using silver nanoparticles (AgNPs) has many advantages over the other nanoparticles (NPs) because of their bactericidal, fungicidal, veridical and oligodynamic properties. It can also be conveniently incorporated into different porous cellulosic materials. Recently, it has been observed that silver-based porous nanocomposites (AgNCs) were efficiently deactivated the bacteria and viruses up to 99%–100% from drinking water. In many studies, silver based nanoparticles are found able to kill around 99.99% for E. coli and MS2 bacteriophage viruses. The present review is aimed at (1) describing the recent advances for AgNPs preparation, (2) explaining the incorporation of AgNPs into paper, polyurethane, ceramic, cotton fabrics and other polymers for water disinfection process, (3) discussing the mechanism of water disinfection/microbial inactivation using AgNPs and AgNCs, and (4) also illustrated that how water sanitation can be helpful to achieve sustainable development goals using silver NPs based developed disinfection systems? Moreover, a number of limitations and future scope have also been discussed. This review will be useful to the researchers and competent authorities engaged in water conservation and management to prepare more effective strategies by using AgNPs and AgNCs.

An overview of silver nano-particles as promising materials for water disinfection

Similarity solutions for unsteady flow behind an exponential shock in a self-gravitating non-ideal gas with azimuthal magnetic field

In the present letter, some invariant solutions of (2+1)-dimensional extended shallow water wave equation are studied. We reduce the equation to an ordinary differential equation(ODE) via the Lie symmetry method. The similarity transformation method is used to determine the group-invariant solutions for the equation. The method plays an important role to reduce the number of independent variables by one in each stage and finally forms an ODE. On the other hand, solutions provide rich physical configuration due to the presence of some distinct arbitrary constants and functions. Furthermore, numerical simulation has been done to trace out the derived results which illustrate the dynamic behavior of these obtained solutions.

Closed form invariant solutions of (2+1)-dimensional extended shallow water wave equation via Lie approach

Propagation of a shock wave in a rotating interplanetary atmosphere with increasing energy

Symmetry reductions, generalized solutions and dynamics of wave profiles for the (2+1)-dimensional system of Broer-Kaup-Kupershmidt (BKK) equations

The propagation of a cylindrical (or spherical) shock wave driven out by a piston moving with time according to an exponential law, in a self-gravitating ideal gas with azimuthal magnetic field is investigated. The initial magnetic field is assumed to be varying according to an exponential law. Solutions are obtained for both the cases of isothermal and adiabatic flows. The effects of variation of ambient magnetic field, gravitational parameter and adiabatic exponent are worked out in detail. It is manifested that the increase in strength of ambient magnetic field has decaying effect on the shock wave however increase in the value of gravitational parameter has reverse effect on the shock strength. The compressibility of the medium is increased in the presence of gravitational field. Also, a comparison between the solutions obtained in the case of isothermal and adiabatic flows is done. Density, pressure, velocity and magnetic field increases, however mass decreases as we move inward from the shock front towards the piston.

Flow behind magnetogasdynamic exponential shock wave in self-gravitating gas

The propagation of cylindrical shock wave in rotational axisymmetric perfect gas under isothermal flow condition with azimuthal magnetic field is investigated. Distributions of gas dynamical quantities are discussed. The density, magnetic pressure, azimuthal fluid velocity and axial fluid velocity are assumed to be varying according to power law with distance from the axis of symmetry in the undisturbed medium. Approximate analytical solutions are obtained by expanding flow variables in power series. Zeroth-order and first-order approximations are discussed with the aid of power series method. Solutions for zeroth-order approximation are constructed in approximate analytical form. The effect of flow parameters namely: shock Cowling number $$C_{0}$$, ambient density variation index q and adiabatic exponent $$\gamma $$ are studied on the flow variables. Consideration of magnetic pressure increases the total energy of disturbance of zeroth order while with increase in ambient density variation index or adiabatic exponent, the total energy of disturbance decreases.

Approximate analytical solution for shock wave in rotational axisymmetric perfect gas with azimuthal magnetic field: Isothermal flow

Propagation of cylindrical shock wave in a self-gravitating perfect gas under the influence of axial magnetic field using Lie group of transformation method is investigated. The flow is considered to be isothermal. Density and magnetic field are assumed to be varying in the undisturbed medium. Two different cases of solutions are brought out by the arbitrary constants appearing in the expressions of infinitesimals of local Lie group of transformations. One is with a power law shock path and the other one is with an exponential law shock path. Numerical solutions are obtained for both the cases of power law and exponential law shock paths. The effects of variation in Alfven-Mach number, gravitational parameter and ambient density variation index for power law shock path and effects of variation in Alfven-Mach number, gravitational parameter and ambient magnetic field variation index on the flow variables in the case of exponential law shock path are studied. Also the effects of increase in value of gravitational parameter and in the strength of ambient magnetic field on the shock strength are investigated. The increase in value of Alfven-Mach number leads to the increase in the density ratio which infers to the decrease in shock strength.

Similarity solutions using Lie group theoretic method for cylindrical shock wave in self-gravitating perfect gas with axial magnetic field: isothermal flow

The propagation of cylindrical ionizing shock waves in a self-gravitating ideal gas with axial magnetic field is investigated. The density and magnetic pressure are assumed to be varying according to power law with distance in the undisturbed medium. Approximate analytical solutions are obtained by expanding the flow variables in power series. The zeroth order and first order approximate solutions are discussed. Solutions for zeroth order approximation are constructed in analytical form. Distributions of hydrodynamical quantities for zeroth order approximation are discussed. Also, the effect of various flow parameters, namely shock Cowling number, adiabatic exponent, gravitational parameter and ambient density variation exponent are studied on the flow variables.

Cylindrical ionizing shock waves in a self-gravitating gas with magnetic field: Power series method

The propagation of cylindrical shock wave under the influence of axial magnetic field in rotating medium under isothermal flow condition is investigated. The density, magnetic field and azimuthal a...

Sumeeta Singh

Papers

Flow behind magnetogasdynamic exponential shock wave in self-gravitating gas

Approximate analytical solution for shock wave in rotational axisymmetric perfect gas with azimuthal magnetic field: Isothermal flow

Similarity solutions using Lie group theoretic method for cylindrical shock wave in self-gravitating perfect gas with axial magnetic field: isothermal flow

Cylindrical ionizing shock waves in a self-gravitating gas with magnetic field: Power series method

Similarity solutions for magnetogasdynamic cylindrical shock wave in rotating ideal gas using Lie Group theoretic method: Isothermal flow