Ansa Alphonsa, Antony; Dr.Sankaran, P G(Cochin University of Science and Technology, September 1, 2005)
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Abstract:
So far, in the bivariate set up, the analysis of lifetime (failure time) data with
multiple causes of failure is done by treating each cause of failure separately. with
failures from other causes considered as independent censoring. This approach is
unrealistic in many situations. For example, in the analysis of mortality data on
married couples one would be interested to compare the hazards for the same cause
of death as well as to check whether death due to one cause is more important for the
partners’ risk of death from other causes. In reliability analysis. one often has
systems with more than one component and many systems. subsystems and
components have more than one cause of failure. Design of high-reliability systems
generally requires that the individual system components have extremely high
reliability even after long periods of time. Knowledge of the failure behaviour of a
component can lead to savings in its cost of production and maintenance and. in
some cases, to the preservation of human life. For the purpose of improving
reliability. it is necessary to identify the cause of failure down to the component
level. By treating each cause of failure separately with failures from other causes
considered as independent censoring, the analysis of lifetime data would be
incomplete. Motivated by this. we introduce a new approach for the analysis of
bivariate competing risk data using the bivariate vector hazard rate of Johnson and
Kotz (1975).
Description:
Department of Statistics, Cochin University of Science and Technology
Sajitha, T S; Dr.Unnikrishnan, P A(Cochin University of Science And Technology, February 19, 2014)
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Abstract:
Burgess reagent first prepared by E. M. Burgess in 1968, is a mild
and selective dehydrating agent for secondary and tertiary alcohols and
due to the amphipolar nature it is gainfully employed in a number of
creative synthetic ventures. A close examination of the structure of
Burgess reagent reveals that it can act as a 1,2-dipole. To the best of our
knowledge, no attempts have been made to tap full synthetic potential of
the amphipolar nature of this reagent and no reports on 1,3-dipolar
addition to a σ-bond in acyclic systems are available in literature. In this
context, we propose to unravel novel applications of Burgess reagent
based on its amphipolar nature.
Rich and multifaceted chemistry of nitrones form the basis of
many successful chemical transformations used in attractive synthetic
strategies. For the last 50 years special attention has been given to
nitrones due to their successful application as building blocks in the
synthesis of various natural and biologically active compounds. Our
interest in nitrones stems out of its unique character: i.e. it is a 1,3-dipole
exhibiting distinct nucleophilic activity.
We reasoned that 1,3-dipole possessing significant nucleophilicity
should react with amphipolar Burgess reagent with elimination of
triethylamine to give the corresponding five-membered ring product by
formal dipolar addition to a σ bond. To test this hypothesis we studied
the reaction of nitrones with Burgess reagent. This thesis reveals our
attempts to explore the [3+2] annulation reaction of nitrones with
Burgess reagent which was found to be followed by a rearrangementinvolving C-to-N aryl migration, ultimately resulting in diarylamines and
carbamates.
We have also examined the reaction of cyanuric chloride with
nitrones in DMF with a view to exploit the nucleophilicty of nitrones and
to unravel the migratory aptitude, if any, observed in this reaction
Description:
Department
of Applied Chemistry, Cochin University of Science and Technology
Anuja, E V; Girish Kumar, K(Cochin University Of Science And Technology, August 6, 2015)
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Abstract:
There is an enormous demand for chemical sensors in many areas and disciplines including chemistry, biology, clinical analysis, environmental science. Chemical sensing refers to the continuous monitoring of the presence of chemical species and is a rapidly developing field of science and technology. They are analytical devices which transform chemical information generating from a reaction of the analyte into an measurable signal. Due to their high selectivity, sensitivity, fast response and low cost, electrochemical and fluorescent sensors have attracted great interest among the researchers in various fields.
Development of four electrochemical sensors and three fluorescent sensors for food additives and neurotransmitters are presented in the thesis. Based on the excellent properties of multi walled carbon nanotube (MWCNT), poly (L-cysteine) and gold nanoparticles (AuNP) four voltammetric sensors were developed for various food additives like propyl gallate, allura red and sunset yellow. Nanosized fluorescent probes including gold nanoclusters (AuNCs) and CdS quantum dots (QDs) were used for the fluorescent sensing of butylated hydroxyanisole, dopamine and norepinephrine.
A total of seven sensors including four electrochemical sensors and three fluorescence sensors have been developed for food additives and neurotransmitters.
Anu Jose; G. Vijay Nair(Cochin University of Science and Technology, August 21, 2014)
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Abstract:
Carbon-carbon and carbon-heteroatom bond formations constitute the
central events in organic synthesis. In view of this, much of the research in
organic synthesis has been focused on devising novel and efficient methods for
such bond constructions. In general, polar, pericyclic and radical methodologies
are employed for this purpose. The polar and radical reactions proceed via
reactive intermediates such as carbanions, enols/enolates, enamines, carbocations,
radical cations, radical anions, carbenes, zwitterions etc. In recent years, there has
been enormous interest in the chemistry of zwitterionic species largely from the
standpoint of their applications in multicomponent reactions (MCRs) and
organocatalytic reactions. Zwitterions formed by the addition of nucleophiles to
electrophilic π-systems such as acetylenic esters and azoesters have been the
subject of extensive investigations; their synthetic utility, however, remained
largely unexplored. Investigations in a number of laboratories, including our own,
have shown that zwitterions of the type mentioned above on reaction with
electrophiles give rise to carbo- and heterocyclic products by 1,3- or 1,4-dipolar
cycloadditions. Recently, allenoates, another class of active π-systems were
introduced to this field. Against this background, a systematic investigation of the
reactions of various zwitterions derived from allenoates with different
electrophiles especially 1,2-diones, were carried out. The results of these studies
are embodied in the thesis entitled “Novel Synthesis of Carbocycles and
Heterocycles Employing Zwitterions Derived from Allenic Esters”.
Rakesh N.; Dr. Prathapan S.(Cochin University of Science and Technology, December 13, 2015)
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Abstract:
Nitrones or azomethine-N-oxides are important precursors for the synthesis of several heterocyclic systems. They belong to the allyl anion type 1,3-dipoles and possess unique structural features which make them extraordinarily useful synthons. They behave as 1,3-dipoles in 1,3-dipolar cycloaddition reactions and as electrophiles in reactions with organometallic reagents. These are the two basic reactions given by nitrones. Nitrones also act as ‘spin traps’ in which they react with short-lived radicals to furnish stable nitroxide radicals which can be detected and identified by electron paramagnetic resonance (EPR) spectroscopy. Recently SmI2 catalysed reductive cross-coupling reactions of nitrones have gained significant interest in which the reactions are initiated by single electron transfer (SET) to nitrones. Apart from these reactions, nitrones are also known to participate in reactions which are initiated by the nucleophilic attack of nitrone-oxygen. In our group, we have also explored the nucleophilic character of nitrones through various reactions. The results obtained enabled us to develop a novel two-step one-pot strategy for quinolines and indoles - the heterocycles renowned for their pharmacological applications, from nitrones and electron deficient acetylenes. Using dibenzoylacetylene and phenylbenzoylacetylene as dipolarophiles, we could introduce a desired functional group at a predetermined position of the quinolines or indoles to be synthesised. In this context, the thesis entitled “NUCLEOPHILIC ADDITION OF NITRONES TO ELECTRON DEFICIENT ACETYLENES AND RELATED STUDIES” portrays our attempt to expand the scope of our
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novel synthetic protocol using ester functionalised acetylenes: dimethyl acetylenedicarboxylate (DMAD) and methyl propiolate.
The thesis is organised in to five chapters. The first chapter briefly describes the different classes of reactions that nitrone functionality can tolerate. The research problem is defined at the end of this chapter. The second chapter describes the synthesis of different nitrones used for the present study. The optimisation and expansion of scope of the novel strategy towards quinoline synthesis is discussed in the third chapter. The fourth chapter portrays the synthesis of indole-3-carboxylates using the novel strategy. In the fifth chapter, the reaction of N-(2,6-dimethylphenyl) and N-(2,4,6-trimethylphenyl)nitrones are discussed. Here we also discuss the mechanistic reinvestigation of Baldwin’s proposal in the isoxazoline-oxazoline rearrangement. The major outcome of the work is given at the end of the thesis.
The structural formulae, schemes, tables and figures are numbered chapter-wise since each chapter of the thesis is organized as an independent unit. All new compounds (except two compounds reported in fourth chapter) are fully characterised on the basis of spectral and analytical data and single crystal X-ray analysis on representative examples. Relevant references are included at the end of individual chapters.
Subi Jacob, George; Dr. Ajayaghosh, A(Regional Research Laboratory (CSIR), October , 2004)
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Abstract:
The main objective of the
present study is to have a detailed investigation on the gelation properties,
morphology and optical properties of small π-conjugated oligomers. For this purpose
we have chosen oligo(p-phenylenevinylene)s (OPVs), a class of molecules which
have received considerable attention due to their unique optical and electronic
properties. Though a large number of reports are available in the literature on the self-assembly properties of tailor made OPVs, none of them pertain to the design of
nanostructures based on organogels. In view of this, we aimed at the creation of
functional chromophoric assemblies of π-conjugated OPVs through the formation of
organogels, with the objective of crafting nanoscopic assemblies of different size and
shape thereby modulating their optical and electronic properties.In order to fulfill the above objectives, the design and synthesis of a variety of
OPVs with appropriate structural variations were planned. The design principle
involves the derivatization of OPVs with weak H-bonding hydroxymethyl end groups
and with long aliphatic hydrocarbon side chains. The noncovalent interactions in these
molecules were expected to lead the formation of supramolecular assembly and gels in
hydrocarbon solvents. In such an event, detailed study of gelation and extensive
analysis of the morphology of the gel structures were planned using advanced
microscopic techniques. Since OPVs are strongly fluorescent molecules, gelation is
expected to perturb the optical properties. Therefore, detailed study on the gelation
induced optical properties as a way to probe the nature and stability of the selfassembly
was planned. Apart from this, the potential use of the modulation of the
optical properties for the purpose of light harvesting was aimed. The approach to this
problem was to entrap an appropriate energy trap to the OPV gel matrix which may
lead to the efficient energy transfer from the OPV gel based donor to the entrapped
acceptor. The final question that we wanted to address in this investigation was the
creation of helical nanostructures through proper modification of the OPV backbone
With chiral handles.The present thesis is a detailed and systematic approach to the
realization of the above objectives which are presented in different chapters of the
thesis.
Vinod Kumar,P B; Thrivikraman,T(Department of Mathematics, September , 2001)
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Abstract:
The present study on chaos and fractals in general topological spaces. Chaos theory originated with the work of Edward Lorenz. The phenomenon which changes order into disorder is known as chaos. Theory of fractals has its origin with the frame work of Benoit Mandelbrot in 1977. Fractals are irregular objects. In this study different properties of topological entropy in chaos spaces are studied, which also include hyper spaces. Topological entropy is a measures to determine the complexity of the space, and compare different chaos spaces. The concept of fractals can’t be extended to general topological space fast it involves Hausdorff dimensions. The relations between hausdorff dimension and packing dimension. Regular sets in Metric spaces using packing measures, regular sets were defined in IR” using Hausdorff measures. In this study some properties of self similar sets and partial self similar sets. We can associate a directed graph to each partial selfsimilar set. Dimension properties of partial self similar sets are studied using this graph. Introduce superself similar sets as a generalization of self similar sets and also prove that chaotic self similar self are dense in hyper space. The study concludes some relationships between different kinds of dimension and fractals. By defining regular sets through packing dimension in the same way as regular sets defined by K. Falconer through Hausdorff dimension, and different properties of regular sets also.
Ancykutty, Joseph; Dr.Krishnamoorthy,A; Dr.Thrivikraman, T(Cochin University of Science and Technology, 2000)
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Abstract:
This thesis Entitled On Infinite graphs and related matrices.ln the last two decades (iraph theory has captured wide attraction as a Mathematical model for any system involving a binary relation. The theory is intimately related to many other branches of Mathematics including Matrix Theory Group theory. Probability. Topology and Combinatorics . and has applications in many other disciplines..Any sort of study on infinite graphs naturally involves an attempt to extend the well known results on the much familiar finite graphs. A graph is completely determined by either its adjacencies or its incidences. A matrix can convey this information completely. This makes a proper labelling of the vertices. edges and any other elements considered, an inevitable process. Many types of labelling of finite graphs as Cordial labelling, Egyptian labelling, Arithmetic labeling and Magical labelling are available in the literature. The number of matrices associated with a finite graph are too many For a study ofthis type to be exhaustive. A large number of theorems have been established by various authors for finite matrices. The extension of these results to infinite matrices associated with infinite graphs is neither obvious nor always possible due to convergence problems. In this thesis our attempt is to obtain theorems of a similar nature on infinite graphs and infinite matrices. We consider the three most commonly used matrices or operators, namely, the adjacency matrix
Description:
Department of mathematics, Cochin University of Science and Technology
Resmi, T; Dr. Lakshmi, B(Cochin University of Science and Technology, August 21, 2015)
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Abstract:
Queueing Theory is the mathematical study of queues or waiting lines.
Queues abound in every day life - in computer networks, in tra c islands,
in communication of electro-magnetic signals, in telephone exchange, in
bank counters, in super market checkouts, in doctor's clinics, in petrol
pumps, in o ces where paper works to be processed and many other
places.
Originated with the published work of A. K. Erlang in 1909 [16] on
congestion in telephone tra c, Queueing Theory has grown tremendously
in a century. Its wide range applications includes Operations Research,
Computer Science, Telecommunications, Tra c Engineering, Reliability
Theory, etc.