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.

An Internet of Things System for Sensing, Analysis & Forecasting Urban Air Quality

Abstract: Constant monitoring of air quality is required in a smart city to improve human health and quality of life. Major cities of the world measure and analyze air quality and pollutant concentration with the help of few static air quality monitoring stations. Roads are arteries of a city and used by majority of the population for commuting and transportation. A low cost air quality sensing system installed in a vehicle that commutes through different routes of the city gives a finegrained real time information about the state of pollutants and air quality in different parts of the city. In this work, we have developed an environment sensing, location aware, Internet of Things system to monitor, collect and analyze the presence of different environmental parameters in real time. Pollution route map of the routes traversed by the vehicle with sensor-setup has been created which can be accessed by mobile users in other vehicles. As air pollution is highly location dependent, there is a need to predict air quality at places for which air quality information is not known. Multiple Linear Regression has been used to used to predict AQI levels from historic data for such locations.

Relativistic nature of carriers: Origin of electron-hole conduction asymmetry in monolayer graphene

Abstract: We report electron-hole conduction asymmetry in monolayer graphene. Previously, it has been claimed that electron-hole conduction asymmetry is due to imbalanced carrier injection from metallic electrodes. Here, we show that metallic contacts have negligible impact on asymmetric conduction and may be either sample or device-dependent phenomena. Electrical measurements show that monolayer graphene based devices exhibit suppressed electron conduction compared to hole conduction due to the presence of donor impurities which scatter electrons more efficiently. This can be explained by the relativistic nature of charge carriers in a graphene monolayer and can be reconciled with the fact that in a relativistic quantum system transport cross section does depend on the sign of scattering potential in contrast to a nonrelativistic quantum system.

Tuning the π-π overlap and charge transport in single crystals of an organic semiconductor via solvation and polymorphism.

Abstract: Polymorphism is a central phenomenon in materials science that often results in important differences of the electronic properties of organic crystals due to slight variations in intermolecular distances and positions. Although a large number of π-conjugated organic compounds can grow as polymorphs, it is necessary to have at disposal a series of several polymorphs of the same molecule to establish clear and predictive structure–property relationships. We report here on the occurrence of two solvates and three polymorphs in single crystalline form of the organic p-type semiconductor 2,2′,6,6′-tetraphenyldipyranylidene (DIPO). When grown from chlorobenzene or toluene, the DIPO crystals spontaneously capture solvent molecules to form two pseudopolymorphic 1 : 1 binary solvates. Independently, three solvent-free DIPO polymorphs are obtained either from the vapor phase or from acetonitrile and benzene. Surprisingly, single crystal field-effect transistors (SC-FETs) reveal that the DIPO 1 : 1 binary solvate grown from chlorobenzene possesses a higher hole mobility (1.1 cm2 V−1 s−1) than the three solvent-free polymorphs (0.02–0.64 cm2 V−1 s−1). A refined crystallographic analysis combined with a theoretical transport model clearly shows that the higher mobility of the solvate results from an improved π–π overlap. Our observations demonstrate that solvation allows to tune the π–π overlap and transport properties of organic semiconductors by selecting appropriate solvents.