Self-Repairable Polymeric Networks: Synthesis and Network Design

This dissertation describes the design, synthesis and development of a new class of polymeric networks that exhibit self-repairing properties under UV exposure. It consists of two parts: (a) modification and synthesis of oxetane (OXE), and oxolane (OXO) substituted chitosan (CHI) macromonomer, and (b) design, and synthesis of self-repairing polyurethane (PUR) networks consisting of modified chitosan. Unmodified CHI consisting of acetamide (-NHCOCH3), primary hydroxyl (-OH), and amine (-NH2) functional groups were reacted with OXE or OXO compounds under basic conditions in order to substitute the 1° –OH groups, and at the same time, convert -NHCOCH3 functionalities into -NH2 groups, while maintaining their un-reacted form to generate OXE/OXO-substituted CHI macromonomer. These substituted CHI macromonomers were incorporated within the PUR backbone by reacting with trifunctional isocyanate in the presence of polyethylene glycol (PEG) and dibutyl tin dilaurate catalyst (DBTDL). Utilizing spectroscopic analysis combined with optical microscopy, these studies showed that the kinetics of self-repair depends on the stoichiometry of the individual entities as well as the time required for self-repairing to occur decrease with increasing OXE quantity within the network. Internal reflection infrared imaging (IRIRI) of OXE/OXO-CHI-PUR networks as well as Raman and Fourier transform IR (FT-IR) studies of OXE/OXO-CHI macromonomers revealed that cationic OXE/OXO ring opening, free radical polyurea (PUA)-to-PUR conversion, along with chair-to-boat conformational changes of CHI backbone are responsible for repairing the damaged network. The network remodeling process, investigated by utilizing micro-thermal analyzer (μTA), revealed that mechanical damage generates small fragments or oligomers within the scratch, therefore glass transition temperature (Tg) decreases, and under UV exposure cross-linking reactions propagate from the bottom of the scratch to the top resulting in an increase of Tg within the scratch and subsequently repair

Urbanisation in West Bengal: An Analysis of Recent Processes

The present work intends to study the recent processes of urbanisation of West Bengal by measuring some selected indices: like level of urbanisation, decadal growth of urban population, rate of urbanisation, pace of urbanisation and urban growth, contribution of growth in urban population to total growth and rural-urban displacement. It is a meso-level study, and 19 districts of the state have been selected as units of study. Using Principal Component Analysis (PCA), the research has identified three principal factors that determine the processes of urbanisation in the state: rural-urban displacement, decadal growth rate and rate of urbanisation. All these three factors responded positively in both primary and secondary loadings

DESIGNING URBAN OPEN SPACES OF BARDDHAMAN TOWN, WEST BENGAL, INDIA

Located in 23014'N latitude and 870 51’ E longitudes, Barddhaman, the Class I town (since 1961) is the head-quarter of the Barddhaman district, West Bengal, India. In term of size of population, the town ranked 13th in the state. Being site and situational advantages, this agriculturally prosperous town since its inception has been recognised as the seat of settled civilization. Urban open spaces are important component to sustainable living in urban areas as they provide environmental, social and economic benefits. Barddhaman town has 122 open space sites comprising an area of 193 ha (8.59%): some are used as playground and rest are vacant as non-used assets. The present work intends to build a framework for rational use of open spaces for the sustenance of the town. For the present study 20 of such open spaces have been selected and comparatively analysed on the basis of standard score of two variables: distance from CBD (1) and areal extent (2) to find out their economic and environmental significance. Finally, a proposal has made for the uses of open spaces to make the town sustainable.Key words: Open space, town, CBD, standard score, environment, sustainable tow

Twisted Galilean symmetry and the Pauli principle at low energies

We show the twisted Galilean invariance of the noncommutative parameter, even in presence of space-time noncommutativity. We then obtain the deformed algebra of the Schr\"odinger field in configuration and momentum space by studying the action of the twisted Galilean group on the non-relativistic limit of the Klein-Gordon field. Using this deformed algebra we compute the two particle correlation function to study the possible extent to which the previously proposed violation of the Pauli principle may impact at low energies. It is concluded that any possible effect is probably well beyond detection at current energies.Comment: 16 pages Latex, 2 figures Some modifications made in the abstract, introduction, typographical errors correcte

Dual families of non-commutative quantum systems

We demonstrate how a one parameter family of interacting non-commuting Hamiltonians, which are physically equivalent, can be constructed in non-commutative quantum mechanics. This construction is carried out exactly (to all orders in the non-commutative parameter) and analytically in two dimensions for a free particle and a harmonic oscillator moving in a constant magnetic field. We discuss the significance of the Seiberg-Witten map in this context. It is shown for the harmonic oscillator potential that an approximate duality, valid in the low energy sector, can be constructed between the interacting commutative and a non-interacting non-commutative Hamiltonian. This approximation holds to order 1/B and is therefore valid in the case of strong magnetic fields and weak Landau-level mixing.Comment: 11 pages, no figure

DESIGNING URBAN OPEN SPACES OF BARDDHAMAN TOWN, WEST BENGAL, INDIA

Located in 23014'N latitude and 870 51’ E longitudes, Barddhaman, the Class I town (since 1961) is the head-quarter of the Barddhaman district, West Bengal, India. In term of size of population, the town ranked 13th in the state. Being site and situational advantages, this agriculturally prosperous town since its inception has been recognised as the seat of settled civilization. Urban open spaces are important component to sustainable living in urban areas as they provide environmental, social and economic benefits. Barddhaman town has 122 open space sites comprising an area of 193 ha (8.59%): some are used as playground and rest are vacant as non-used assets. The present work intends to build a framework for rational use of open spaces for the sustenance of the town. For the present study 20 of such open spaces have been selected and comparatively analysed on the basis of standard score of two variables: distance from CBD (1) and areal extent (2) to find out their economic and environmental significance. Finally, a proposal has made for the uses of open spaces to make the town sustainable.Key words: Open space, town, CBD, standard score, environment, sustainable tow