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.

Treatment of domestic sewage and leachate using a moving bed hybrid bioreactor

Abstract: The treatment of domestic sewage using a moving bed hybrid bioreactor (MBHBR) was investigated by varying the concentrations of chemical oxygen demand (COD) (156 ± 14-1141 ± 78 mg/L), ammonia (NH3-N) (2 ± 0.08-48.24 ± 0.93 mg/L), phosphorus (PO4-P) (97 ± 3.2-281 ± 2.65 mg/L), and hydraulic retention times (HRTs). Initially, the reactor was operated at start-up mode (COD: 156 ± 14 mg/L), and gradually the COD concentrations were increased from phase-I (257 ± 24 mg/L) to phase-V (1141 ± 78 mg/L) by reducing the HRTs from 48 to 3 h. A significant improvement in COD removal, maximum up to 96%, was observed at a concentration of 858 ± 51 mg/L (phase-IV), then a sudden drop up to 81% was observed at a higher concentration of 1141 ± 78 mg/L (phase-V). Due to the increase in COD concentrations, average NH3-N removal was dropped from 85 to 32% from phase-I to Phase-V, respectively. In addition, the stability of MBHBR was studied to understand its performance in shut-down and shock loading phases. The co-treatment of sewage and leachate was also performed in MBHBR (COD: 864-881 mg/L and HRT: 6 h), which showed a COD removal of 77%–80% and NH3-N removal of 60%–94%. Proteobacteria was identified as a predominant species in MBHBR, which played a significant role in the co-treatment of sewage and leachate. The maximum biodegradation rate ( r max ) and half-saturation constant ( K s ) were estimated as 13.3 mg/L h and 361.8 mg/L, respectively.

Stability analysis of a rigid rotor supported by two-lobe hydrodynamic journal bearings operating with a non-Newtonian lubricant:

Abstract: In the present work, an investigation has been performed on a rigid rotor supported by two-lobe journal bearings operating with a non-Newtonian lubricant. The governing Reynolds equation for pressu...

Analysis of degradation mechanisms in donor–acceptor copolymer based organic photovoltaic devices using impedance spectroscopy

Abstract: The stability of organic photovoltaic (OPV) devices in ambient conditions has been a serious issue which needs to be addressed and resolved timely. In order to probe the degradation mechanism in a donor–acceptor polymer PDPP-TNT: PC71BM bulk heterojunction based OPV devices, we have studied current density–voltage (J–V) behavior and impedance spectroscopy of fresh and aged devices. The current–voltage characteristic of optimized fresh devices exhibit a short circuit current density (J sc) of 8.9 mA cm−2, open circuit voltage (V oc) of 0.79 V, fill factor (FF) of 54.6%, and power conversion efficiency (PCE) of 3.8%. For aged devices, J sc, V oc, FF, and PCE were reduced to 57.3%, 89.8%, 44.3% and 23.7% of its initial value, respectively. The impedance spectra measured under illumination for these devices were successfully fitted using a CPE-based circuit model. For aged devices, the low-frequency response in impedance spectra suggests an accumulation of the photo-generated charge carriers at the interfaces which leads to a significant lowering in fill factor. Such degradation in device performance is attributed to the incorporation of oxygen and water molecules in devices. An increase in the recombination resistance indicates a deterioration of free charge carrier generation and conduction in devices.

Game of coordination for bacterial pattern formation: a finite automata modelling

Abstract: In this paper, we use game theory to describe the emergence of self-organization and consequent pattern formation through communicative cooperation in Bacillus subtilis colonies. The emergence of cooperative regime is modelled as an n-player Assurance game, with the bacterial colonies as individual players. The game is played iteratively through cooperative communication, and mediated by exchange of information about the local environment between the different bacterial colonies comprising the system. The iteration causes the interactive system to grow and produce beautiful complex spatial patterns signaling the emergence of self-organization. In laboratory, we have the bacterial growth environment mimicked in Petri dish, where chemical stress is introduced in a three- fold manner: through modification of nutrition and substrate amounts and introducing an antibiotic in the system. In our model, bacteria colonies, treated asindividual players, interact within the environment and grow according to a set of rules. The rules capture the biotic processes that allow bacteria to grow in the hostile environment, and cope with the stress. We find the effects of sophisticated communications and information-sharing between bacterial colonies to be a vital determinant for bacterial growth, which is manifested in the Petri dish as complex spatial patterns, often at fractal scales. As a formal description of the above game, we model the emergence of this cooperative behaviour as finite deterministic automata, whose transition function is informed by the Assurance game pay-off. Consequently, the exercise allows us to derive a grammar that provides the rules for describing the bacterial interactions leading to the emergence of the spatial structures.