North Eastern Hill University

About: North Eastern Hill University is a education organization based out in Shillong, Meghalaya, India. It is known for research contribution in the topics: Population & Ruthenium. The organization has 2318 authors who have published 4476 publications receiving 48894 citations.

Pyrene-Based Chemosensor for Picric Acid-Fundamentals to Smartphone Device Design.

Abstract: Developing a fluorescent probe for the selective and sensitive detection of explosives is a topic of continuous research interest. Additionally, underlying the principles behind the detection mechanism is indeed providing substantial information about the design of an efficient fluorescence probe. In this context, a pyrene-tethered 1-(pyridin-2-yl)imidazo[1,5-a]pyridine-based fluorescent probe (TL18) was developed and employed as a fluorescent chemosensor for nitro explosives. The molecular structure of TL18 was well-characterized by NMR and EI-MS spectrometric techniques. UV-visible absorption, steady-state, and time-resolved fluorescence spectroscopic techniques have been employed to explicate the photophysical properties of TL18. The fluorescent nature of the TL18 probe was explored for detection of nitro explosives. Intriguingly, the TL18 probe was selectively responsive to picric acid over other explosives. The quantitative analysis of the fluorescence titration studies of TL18 with picric acid proved that the probe achieved a detection limit of 63 nM. Further, DFT and QTAIM studies were used to establish the nature of the sensing mechanism of TL18. The hydrogen-bonding interactions are the reason for the imperative sensing property of TL18 for picric acid. Thus, our experimental and theoretical studies provide an adequate and appropriate prerequisite for an efficient fluorescent probe. Furthermore, a smartphone-interfaced portable fluorimeter module is developed to facilitate sensitive and real-time sensing of picric acid. This portable module was capable of detecting picric acid down to 99 nM. Eventually, these studies will have a significant impact on development and application of a new class of chemosensors for detection of explosives.

Predictions for the proton lifetime in minimal nonsupersymmetric SO(10) models: An update.

Abstract: We present our best estimates of the uncertainties due to heavy particle threshold corrections on the unification scale ${\mathit{M}}_{\mathit{U}}$, intermediate scale ${\mathit{M}}_{\mathit{I}}$, and coupling constant ${\mathrm{\ensuremath{\alpha}}}_{\mathit{U}}$ in the minimal nonsupersymmetric SO(10) models. Using recent data from the CERN ${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ collider LEP on ${\mathrm{sin}}^{2}$${\mathrm{\ensuremath{\theta}}}_{\mathit{W}}$ and ${\mathrm{\ensuremath{\alpha}}}_{\mathrm{strong}}$ to obtain the two-loop-level predictions for ${\mathit{M}}_{\mathit{U}}$ and ${\mathrm{\ensuremath{\alpha}}}_{\mathit{U}}$, we update the predictions for the proton lifetime in minimal nonsupersymmetric SO(10) models.

Correlating Early Evolution of Parasitic Platyhelminths to Gondwana Breakup

Abstract: Investigating patterns and processes of parasite diversification over ancient geological periods should involve comparisons of host and parasite phylogenies in a biogeographic context. It has been shown previously that the geographical distribution of host-specific parasites of sarcopterygians was guided, from Palaeozoic to Cainozoic times, mostly by evolution and diversification of their freshwater hosts. Here, we propose phylogenies of neobatrachian frogs and their specific parasites (Platyhelminthes, Monogenea) to investigate coevolutionary processes and historical biogeography of polystomes and further discuss all the possible assumptions that may account for the early evolution of these parasites. Phylogenetic analyses of concatenated rRNA nuclear genes (18S and partial 28S) supplemented by cophylogenetic and biogeographic vicariance analyses reveal four main parasite lineages that can be ascribed to centers of diversity, namely Australia, India, Africa, and South America. In addition, the relationships among these biogeographical monophyletic groups, substantiated by molecular dating, reflect sequential origins during the breakup of Gondwana. The Australian polystome lineage may have been isolated during the first stages of the breakup, whereas the Indian lineage would have arisen after the complete separation of western and eastern Gondwanan components. Next, polystomes would have codiverged with hyloid sensu stricto and ranoid frog lineages before the completion of South American and African plate separation. Ultimately, they would have undergone an extensive diversification in South America when their ancestral host families diversified. Therefore, the presence of polystome parasites in specific anuran host clades and in discrete geographic areas reveals the importance of biogeographic vicariance in diversification processes and supports the occurrence and radiation of amphibians over ancient and recent geological periods.

Measuring the Trilinear Couplings of MSSM Neutral Higgs Bosons at High-Energy e + e Colliders

Abstract: We present a detailed analysis of multiple production of the lightest $\mathrm{CP}$-even Higgs boson $(h)$ of the minimal supersymmetric standard model (MSSM) at high-energy ${e}^{+}{e}^{\ensuremath{-}}$ colliders. We consider the production of the heavier $\mathrm{CP}$-even Higgs boson $(H)$ via Higgs-strahlung ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}ZH,$ in association with the $\mathrm{CP}$-odd Higgs boson $(A)$ in ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}AH,$ or via the fusion mechanism ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{ u}}_{e}{\overline{\ensuremath{ u}}}_{e}H,$ with $H$ subsequently decaying through $\stackrel{\ensuremath{\rightarrow}}{H}hh,$ thereby resulting in a pair of lighter Higgs bosons $(h)$ in the final state. These processes can enable one to measure the trilinear Higgs couplings ${\ensuremath{\lambda}}_{\mathrm{Hhh}}$ and ${\ensuremath{\lambda}}_{\mathrm{hhh}},$ which can be used to theoretically reconstruct the Higgs potential. We delineate the regions of the MSSM parameter space in which these trilinear Higgs couplings could be measured at a future ${e}^{+}{e}^{\ensuremath{-}}$ collider. In our calculations, we include in detail the radiative corrections to the Higgs sector of the MSSM, especially the mixing in the squark sector.