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.

Observation and measurement of an extra phase shift created by optically detuned light storage in metastable helium

Abstract: Electromagnetically induced transparency (EIT) in metastable helium at room temperature is experimentally shown to exhibit light storage capabilities for intermediate values of the detuning between the coupling and probe beams and the center of the atomic Doppler profiles. An additional phase shift is shown to be imposed to the retrieved pulse of light when the EIT protocol is performed at non-zero optical detunings. The value of this phase shift is measured for different optical detunings between 0 and 2 GHz, and its origin is discussed.

Recent Advances in Thermoelectric Materials and Solar Thermoelectric Generators — A Critical Review

Abstract: Due to the fact that much of the world's best solar resources are inversely correlated with population centers, significant motivation exists for developing technology which can deliver reliable and autonomous conversion of sunlight into electricity. Thermoelectric generators are gaining incremental ground in this area since they do not require moving parts and work well in remote locations. Thermoelectric materials have been extensively used in space satellites, automobiles, and, more recently, in solar thermal applications as power generators, known as solar thermoelectric generators (STEG). STEG systems are gaining significant interest in both concentrated and non-concentrated systems and have been employed in hybrid configurations with solar thermal and photovoltaic systems. In this article, the key developments in the field of thermoelectric materials and on-going research work on STEG design conducted by various researchers to date are critically reviewed. Finally, we highlight the strategic research directions being undertaken to make highly efficient thermoelectric materials for developing a cost-effective STEG system, which could serve to bring this technology towards commercial readiness.

Can the local electric field be a descriptor of catalytic activity? A case study on chorismate mutase

Abstract: The current theoretical perception of enzymatic activity is highly reliant on the determination of the activation energy of the reactions, which is often calculated using computationally demanding quantum mechanical calculations. With the ever-increasing use of bioengineering techniques that produce too many variants of the same enzyme, a fast and accurate way to study the relative efficiency of enzymes is currently in high demand. Here, we propose the local electric field (LEF) of the enzyme along the reaction axis as a descriptor for the enzymatic activity using the example of chorismate mutase in its native form and several variants (R90A, R90G, and R90K/C88S). The study shows a direct correlation between the calculated enzymatic EF and the enzymatic activity for all the complexes. MD simulations of the Michaelis complex and the transition state analog (TSA) show a stabilizing force on the TSA due to the enzymatic EF. QM/MM and QM-only DFT calculations in the presence of an external electric field (EEF) oriented along the reaction axis show that the electric field can interact with the dipole moment of the TS, thereby stabilizing it and thus lowering the activation energy.

Pyrrolidine and piperidine based chiral spiro and fused scaffolds via build/couple/pair approach

Abstract: A versatile stereoselective diversity oriented synthetic pathway to the possible spiro and fused diverse heterocyclic small molecules is described. The strategy involved the “build–couple–pair” approach involving an SNAr, Michael addition and Mannich reaction on chiral acyl bicyclic lactams 2a/b, followed by a cyclization onto the inbuilt scaffold electrophile, thereby leading to asymmetric fused and spirocyclic nitrogen heterocycles. A “post-pair” phase has been incorporated to generate more polar compounds. We used Principal Component Analysis (PCA) and polar moment of inertia to evaluate the shape-space diversity of our scaffolds with respect to a commercial database and observed extraordinary diversity within the scaffold network. We further calculated the polar surface area (PSA) of our molecules which is an indicator for drug cell permeability.

Satb2 acts as a gatekeeper for major developmental transitions during early vertebrate embryogenesis

Abstract: Zygotic genome activation (ZGA) initiates regionalized transcription underlying distinct cellular identities. ZGA is dependent upon dynamic chromatin architecture sculpted by conserved DNA-binding proteins. However, the direct mechanistic link between the onset of ZGA and the tissue-specific transcription remains unclear. Here, we have addressed the involvement of chromatin organizer Satb2 in orchestrating both processes during zebrafish embryogenesis. Integrative analysis of transcriptome, genome-wide occupancy and chromatin accessibility reveals contrasting molecular activities of maternally deposited and zygotically synthesized Satb2. Maternal Satb2 prevents premature transcription of zygotic genes by influencing the interplay between the pluripotency factors. By contrast, zygotic Satb2 activates transcription of the same group of genes during neural crest development and organogenesis. Thus, our comparative analysis of maternal versus zygotic function of Satb2 underscores how these antithetical activities are temporally coordinated and functionally implemented highlighting the evolutionary implications of the biphasic and bimodal regulation of landmark developmental transitions by a single determinant.