UV Induced Processes in Biomolecules, Hydrated Clusters and Stark Deflected Beams

The nanoscale processes by which UV irradiation initiates damage in biological material have not yet been fully elucidated. This represents a barrier to innovations in radiotherapy and also limits our understanding of the molecular origins of life. Experiments on gas-phase biological building blocks can reveal detailed information via comparisons with high-level calculations, while parallel studies of biomolecular clusters offer a route to assess the effects of condensed biological environments. This thesis investigates the stabilities and relaxation pathways of isolated and clustered nucleobases in neutral electronic excited states and ionic states. Furthermore, it presents a new laser thermal desorption facility and reports advances in applying Stark deflection to narrow the range of molecular and cluster configurations in continuous supersonic beams. The key analytical tool in this thesis is UV multi-photon ionization time-of-flight mass spectrometry (MPI-TOF). High-resolution measurements on the RNA base uracil and its fully-deuterated analogue provide new evidence supporting a ring-opening process in a neutral electronic excited state. Comparing experiments on uracil in supersonic beams and from the laser thermal desorption source show that the MPI channel that marks this ring-opening process is not sensitive to the vaporization method and aid comparisons with time-resolved experiments at Heriot Watt University. Exploiting the capabilities of reflectron mass spectrometry to study the metastable dissociation of excited ions and cluster ions is a major theme in this thesis. Photon energy thresholds for metastable dissociation from multi-photon ionized uracil and thymine are reported for the first time. We argue that these thresholds can provide a new route to deduce the adiabatic energies of neutral electronic excited states. Further metastable dissociation experiments and detailed comparisons with ab initio calculations provide the most detailed study of the stable configurations of thymine-water cluster ions to date. The variety of different structural configurations of biomolecules and clusters in neutral target beams presents a major challenge in the experimental study of radiation-induced processes. Stark deflection in electric field gradients offers a powerful method to address this challenge and has previously been used to select specific polar species from mixed pulsed supersonic beams. However, the low pulsing frequencies of such beams are unsuitable to study many collision-induced processes. This thesis reports on the development of a system at the Open University that uses Stark deflection to manipulate continuous beams with the ultimate aim of probing electron attachment processes in selected clusters. Controlled deflection of nitromethane is demonstrated in a helium beam with 94% recovery of the deflected molecules. The manipulation of nucleobases using Stark deflection is achieved for the first time, with continuous argon and krypton expansions providing the necessary rotational cooling. Isolated and clustered nucleobases show very different responses to the deflecting fields, providing a method to gain insights into the origins of specific fragment ions in MPI and electron impact ionization experiments

Research Publication Pattern of Journal of Indian Library Association (JILA): A Bibliometric Analysis during 2015-2019

The present paper aims to investigate the publishing pattern of The Journal of Indian Library Association (JILA) published during 2015-2019. During this period, a total of 107 research articles has been published by various contributors across the country. The study explores the bibliometric aspects like distribution of articles, year-wise growth of publications, authorship pattern of publication their degree of collaboration and an average rate of publication per author. The maximum growth rate was measured in the year 2019 with 21.73%, and individual authors published 47.67% of scholarly articles. The findings of the study demonstrate the strength of the Journal, which will be helpful for further development

Comparative Pressure Drop in Laminar and Turbulent Flows in Circular Pipe with and without Baffles using FEV

The study of Turbulent flow characteristics in complex geometries receives considerable attention due to its Importance in many engineering applications and has been the subject of interest for researchers. Some of these include the energy conversion systems found in same design of heat exchangers, nuclear reactor, solar collectors & cooling of industrial machines and electronic components. Flow in channels with baffle plates occurs in many industrial applications such as heat exchangers, filtration, chemical reactors, and desalination. These baffles cause turbulence which leads to increases friction within the pipe or duct and leads significant pressure drop. This work is concern with the comparative flow and pressure distribution analysis of a smooth and segmented Baffles pipe. In which pressure drop during the flow is examined and with the help of hydrodynamic characteristics performance is predicted with the help of Finite element volume tool ANSYS- Fluent, where simulation is been done. The goal is to carry out evaluating pressure drop across the pipe using different turbulent model and at simulation is done for wide range of Reynolds number in both laminar and turbulent flow regimes. The FEV results are validated with well published results in literature and furthermore with experimentation. The FEV and experimental results show good agreement