Maharshi Dayanand University

About: Maharshi Dayanand University is a education organization based out in Rohtak, Haryana, India. It is known for research contribution in the topics: Photoluminescence & Luminescence. The organization has 1561 authors who have published 2845 publications receiving 33699 citations.

Nanostructured graphene/Fe3O4 incorporated polyaniline as a high performance shield against electromagnetic pollution

Abstract: The development of high-performance shielding materials against electromagnetic pollution requires mobile charge carriers and magnetic dipoles. Herein, we meet the challenge by building a three-dimensional (3D) nanostructure consisting of chemically modified graphene/Fe3O4(GF) incorporated polyaniline. Intercalated GF was synthesized by the in situ generation of Fe3O4 nanoparticles in a graphene oxide suspension followed by hydrazine reduction, and further in situ polymerization with aniline to form a polyaniline composite. Spectroscopic analysis demonstrates that the presence of GF hybrid structures facilitates strong polarization due to the formation of a solid-state charge-transfer complex between graphene and polyaniline. This provides proper impedance matching and higher dipole interaction, which leads to the high microwave absorption properties. The higher dielectric loss (e′′ = 30) and magnetic loss (μ′′ = 0.2) contribute to the microwave absorption value of 26 dB (>99.7% attenuation), which was found to depend on the concentration of GF in the polyaniline matrix. Moreover, the interactions between Fe3O4, graphene and polyaniline are responsible for superior material characteristics, such as excellent environmental (chemical and thermal) degradation stability and good electric conductivity (as high as 260 S m−1).

Ratio and Product Type Exponential Estimators

Abstract: This paper proposes new ratio and product type estimators for estimating the mean of the finite population using information on single auxiliary variable. The bias and mean square error of these estimators have been obtained. These estimators are compared for their precision with usual mean per unit, ratio and product estimators and are found to be more efficient in many practical situations. Further, it is shown that these estimators reduce to regression estimator.

Water quality assessment of lake water: a review

Abstract: Ever increasing population, urbanization and modernization are posing problems of sewage disposal and contamination of surface waters like lakes. Natural water gets contaminated due to weathering of rocks, leaching of soils and mining processing, etc. Various types of problems in lake which cause nutrient enrichment in lake have been reviewed. Land use change and longer growing seasons could increase the use of fertilizers with subsequent leaching to watercourses, rivers and lakes, increasing the risk of eutrophication and loss of biodiversity. Water quality can be assessed by various parameters such as BOD, temperature, electrical conductivity, nitrate, phosphorus, potassium, dissolved oxygen, etc. Heavy metals such as Pb, Cr, Fe, Hg, etc. are of special concern because they produce water or chronic poisoning in aquatic animals. Harmful algal blooms are becoming increasingly common in freshwater ecosystems globally. Pollution by plastic debris is an increasing environmental concern in water bodies, where it affects open-water, shoreline and benthic environments. Surface water densities of plastics are as high as those reported for areas of litter accumulation within oceanic gyres. Different methods have been used to analyse the water quality of lake such as Hyperion, water quality index and hazard quotient. It is recommended that pollution prevention and water re-use should be adopted in combination with the recycling of nutrients in controlled urban agriculture.