Johny,Scaria; Unnikrishnan Nair, N(Department of Statistics,Faculty of Science, 2003)
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Abstract:
The study deals with the distribution theory and applications of concomitants from the Morgenstern family of bivariate distributions.The Morgenstern system of distributions include all cumulative distributions of the form FX,Y(X,Y)=FX(X) FY(Y)[1+α(1-FX(X))(1-FY(Y))], -1≤α≤1.The system provides a very general expression of a bivariate distributions from which members can be derived by substituting expressions of any desired set of marginal distributions.It is a brief description of the basic distribution theory and a quick review of the existing literature.The Morgenstern family considered in the present study provides a very general expression of a bivariate distribution from which several members can be derived by substituting expressions of any desired set of marginal distributions.Order statistics play a very important role in statistical theory and practice and accordingly a remarkably large body of literature has been devoted to its study.It helps to develop special methods of statistical inference,which are valid with respect to a broad class of distributions.The present study deals with the general distribution theory of Mk, [r: m] and Mk, [r: m] from the Morgenstern family of distributions and discuss some applications in inference, estimation of the parameter of the marginal variable Y in the Morgestern type uniform distributions.
Zachariah,E J; Dr.Nair, K G(Cochin University of Science And Technology, August , 1981)
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Abstract:
The need for improved feed systems for large reflector antennas employed in Radio Astronomy and Satellite tracking spurred the interest in horn antenna research in
the 1960's. The major requirements were to reduce spill over, cross-polarisation losses,and to enhance the aperture efficiency to the order of about 75-8O%L The search for such a feed culminated in the corrugated horn. The corrugat1e 1 horn triggered widespread interest and enthusiasm, and a large amount of work(32’34’49’5O’52’53’58’65’75’79)has already been done on this type of antennas. The properties of corrugated surfaces has been investigated in detail.
It was strongly felt that the flange technique and the use of corrugated surfaces could be merged together to obtain the advantages of both. This is the idea behind the present work. Corrugations are made on the surface of flange elements. The effect of various corrugation parameters are studied. By varying the flange parameters, a good amount of data is collected and analysed to ascertain the effects of corrugated flanges. The measurements are repeated at various frequencies, in the X— and S-bands. The following parameters of the system were studied: (a) beam shaping (b) gain (c) variation of V.S.U.R. (d) possibility of obtaining circularly polarised
radiation from the flanged horn. A theoretical explanation to the effects of corrugated flanges
is attempted on the basis of the line-source theory. Even though this theory utilises a simplified model for the calculation of radiation patterns, fairly good agreement between the computed pattern and experimental results are observed.
Description:
Department of physics, Cochin University of Science And Technology
Aiswarya, N.; Dr. M.R. Prathapachandra Kurup(Cochin University of Science and Technology, April 10, 2016)
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Abstract:
The current scenario of coordination chemistry is witnessing the exploitation
of coordination bonds and noncovalent interactions to generate self-assemblies of
various dimensions having not only aesthetic values but also countless applications
and that paved way for supramolecular chemistry/crystal engineering. Most of
such fascinating work employs Schiff bases obtained by the condenzation of an
amine and a carbonyl compound. The use of diamines in the synthesis of highnuclearity
complexes utilizes the bridging capacity of phenoxo atoms. Whereas in
the case of N2O donor tridentate Schiff bases (N-substituted diamines with
salicylaldehyde or its derivatives), coligands are employed to generate structures of
variable composition apart from satisfying the coordination number. Among the
various coligands known, pseudohalides (azido, cyanato, thiocyanato, dicyanamido)
deserve special attention on account of its versatile modes of binding. In addition
to the structural variety, such Schiff base complexes have its signature in the field
of catalysis, luminescence, gas adsorption and magnetic materials which make the
arena conspicuous. The recognition of plasticity of copper(II) metal with respect to
its coordination number and its ubiquitous nature as active sites in many metalloenzymes
fuelled us to work with this metal. The results of our efforts to explore
the role of various interaction forces constitute the subject matter of the thesis
entitled “Crystalline architectures of copper(II) complexes derived from halogen
substituted carbonyl compounds: Interplay of covalent and non-covalent forces”.
The work embodied in this thesis was carried out by the author in the Department of
Applied Chemistry, CUSAT, Kochi, during the period 2011-2016 and is divided into
eight chapters.
Jinsa, Jacob Mary; Dr.Prathapachandra Kurup,M R(Cochin University Of Science And Technology, September , 2013)
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Abstract:
Thiosemicarbazones have emerged as an important class of ligands
over a period of time, for a variety of reasons, such as variable donor
properties, structural diversity and biological applications. Interesting as
the coordination chemistry may be, the driving force for the study of these
ligands has undoubtedly been their biological properties and the majority
of the 3000 or so publications on thiosemicarbazones since 2000 have
alluded to this feature. Thiosemicarbazones with potential donor atoms in
their structural skeleton fascinate coordination chemists with their versatile
chelating behavior. The thiosemicarbazones of aromatic aldehydes and
ketones form stable chelates with transition metal cations by utilizing both
their sulfur and azomethine nitrogen as donor atoms. They have been
shown to possess a diverse range of biological activities including
anticancer, antitumor, antibacterial, antiviral, antimalarial and antifungal
properties owing to their ability to diffuse through the semipermeable
membrane of the cell lines. The enhanced effect may be attributed to the
increased lipophilicity of the metal complexes compared to the ligand
alone.
Description:
Department of Applied Chemistry, Cochin University of Science and Technology
Jessy Emmanuel; Dr.Prathapachandra Kurup,M R(Cochin University Of Science And Technology, July 26, 2012)
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Abstract:
Supra molecular architectures of coordination complexes of liydrazones
through non covalent interactions have been explored. Molecular self—assernbly
driven by weak interactions such as hydrogen— bonding, K '”T[, C-1-I‘ "TE, van
der Waals interactions, and so forth are currently of tremendous research
interest in the fields of molecule based materials. The directional properties of
the hydrogembonding interaction associate discrete molecules into aggregate
structures that are sufficiently stable to be considered as independent chemical
species. Chemistry can borrow nature’s strategy to utilize hydrogen-bonding as
Well as other noncovalent interactions as found in secondary and tertiary
structures of proteins such as the double helix folding of DNA, hydrophobic
selflorganization of phospholipids in cell membrane etc. In supramolecular
chemistry hydrogen bonding plays an important role in forming a variety of
architectures. Thus, the wise modulation and tuning of the complementary sites
responsible for hydrogen—bond formation have led to its application in
supramolecular electronics, host-guest chemistry, self-assembly of molecular
capsules, nanotubes etc. The work presented in this thesis describes the synthesis and
characterization of metal complexes derived from some substituted
aroylhydrazones. The thesis is divided into seven chapters.
Description:
Department of Applied Chemistry, Cochin University of Science and
Technology
Priya Rajan, S; Dr.Mohanan, P V(Cochin University Of Science And Technology, May , 2013)
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Abstract:
The scope of the work was to synthesis few biologically active derivatives
of curcumin. The derivatives were prepared by altering the keto-enol centre of
curcumin by various reagents. This particular reaction centre for preparing
derivative was selected keeping in mind the controversy regarding the major site
responsible for antioxidant mechanism of curcumin. Most of the mechanistic study
done earlier was by varying the constituents in one or both of the phenol ring
present in the curcumin. The alterations at the keto-enol moiety may throw an
insight into the role of the diketo moiety towards the antioxidant mechanism. Since
recently curcumin has been suggested as a chemotherapeutic agent for various
ailments, we also decided to check the DNA intercalating property of the
derivatives synthesised.
Description:
Department of Applied Chemistry
Cochin University of Science and Technology
Sonal Kumar, Jain; Dr.Anil, Bhardwaj(Cochin University Of Science And Technology, January , 2013)
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Abstract:
An attempt has been made in this thesis to model some of the emissions observed
by SPICAM and SPICAV on Mars and Venus, respectively, viz., CO Cameron band,
CO+
2 ultraviolet doublet, N2 triplet bands, atomic oxygen green (5577 A), red doublet
(6300, 6364 A), and ultraviolet (2972 A) emissions. One of major sources of these
emissions is photoelectron impact ionization/excitation. In this thesis, an electron
degradation model based on Monte Carlo technique has been developed to calculate
the production/excitation rates of above mentioned emissions due to electron impact.
The limb brightness pro les of emissions are calculated and compared with the observations
wherever available. The e ect of various model input parameters on dayglow
emissions intensities is also evaluated
Description:
Space Physics Laboratory
Vikram Sarabhai Space Centre
Indian Space Research Organisation
Thiruvananthapuram
Jayakrishnan, R; Dr.Vijayakumar, K P(Cochin University of Science & Technology, April , 2008)
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Abstract:
The present thesis can be divided into three areas:1) the
fabrication of a low temperature photo-luminescence and photoconductivity
measuring unit 2) photo-luminescence in the chalcopyrite
CulnSez and CulnS2 system for defect and composition analysis and
3) photo-luminescence and photo-conductivity of In:JS3. This thesis
shows that photo-luminescence is one of most essential semiconductor
characterization tool for a scientific group working on photovoltaics.
Tools which can be robust, non-destructive, requiring minimal sample
preparation for analysis and most informative of the device
applications are sought after by industries and this thesis is towards
establishing photo-luminescence as "THE" tool for semiconductor
characterization. The possible application of photo-luminescence as a
tool for compositional and quality analysis of semiconductor thin
films has been worked upon by this thesis. Photo-conductivity
complement photo-luminescence and together they provide all the
information required for the fabrication of an opto-electronic device.
Description:
Department of Physics,
Cochin University of Science and Technology
Ramkumar, S; Dr.Vijayakumar, K P(Cochin University of Science & Technology, January , 2006)
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Abstract:
In this work we present the results of our attempt to build a compact
photothermal spectrometer capable of both manual and automated mode of
operation.The
salient features of the system include the ability to analyse thin film, powder
and polymer samples. The tool has been in use to investigate thermal, optical
and transport properties. Binary and ternary semiconducting thin films were
analysed for their thermal diffusivities. The system could perform thickness
measurements nondestructively. Ion implanted semiconductors are widely
studied for the effect of radiation induced defects. We could perform
nondestructive imaging of defects using our spectrometer.The results reported in his thesis on the above in
addition to studies on In2S3 and transparent conducting oxide ZnO have been
achieved with this spectrometer. Various polymer samples have been easily
analysed for their thermal diffusivities. The technique provided ease of
analysis not achieved with conventional techniques like TGA and DSC.
Industrial application of the tool has also been proved by analyzing defects of
welded joints and adhesion of paints. Indigenization of the expensive lock-in-amplifier
and automation has been the significant achievement in the course of
this dissertation. We are on our way to prove the noise rejection capabilities of
our PC LIA.
Description:
Department of Physics,
Cochin University of Science and Technology
Dhanya, T J; Ramaiah, D(Cochin University of Science and Technology, October 27, 2014)
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Abstract:
The focus of self-assembly as a strategy for the synthesis has been confined largely to molecules, because of the importance of manipulating the structure
of matter at the molecular scale. We have investigated the influence
of temperature and pH, in addition to the concentration of the capping agent used for the formation of the nano-bio conjugates. For example, the formation of the narrower size distribution of the nanoparticles was observed with the increase in the concentration of the protein, which supports the fact that γ-globulin acts both as a controller of nucleation as well as stabiliser.
As analyzed through various photophysical, biophysical and microscopic
techniques such as TEM, AFM, C-AFM, SEM, DLS, OPM, CD and FTIR, we observed that the initial photoactivation of γ-globulin at pH 12 for 3 h resulted in small protein fibres of ca. Further irradiation for 24 h, led to the formation of selfassembled long fibres of the protein of ca. 5-6 nm and observation of surface plasmon resonance band at around 520 nm with the concomitant quenching of luminescence intensity at 680 nm. The observation of light triggered self-assembly of the protein and its effect on controlling the fate of the anchored nanoparticles can be compared with the naturally occurring process such as photomorphogenesis.Furthermore,our approach offers a way to understand the role played by the self-assembly of the protein in ordering and knock out of the metal nanoparticles and also in the design of nano-biohybrid materials for medicinal and optoelectronic applications. Investigation of the potential applications of NIR absorbing and water soluble squaraine dyes 1-3 for protein labeling and anti-amyloid agents forms the subject
matter of the third chapter of the thesis. The study of their
interactions with various proteins revealed that 1-3 showed unique interactions
towards serum albumins as well as lysozyme. 69%, 71% and
49% in the absorption spectra as well as significant quenching in the fluorescence
intensity of the dyes 1-3, respectively. Half-reciprocal analysis of the absorption data and isothermal titration calorimetric (ITC) analysis of the titration experiments gave a 1:1 stoichiometry for the complexes formed between the lysozyme and squaraine dyes with association constants (Kass) in the range 104-105 M-1. We have determined the changes in the free energy (ΔG) for the complex formation and the values are found to be -30.78, -32.31 and -28.58 kJmol-1, respectively for the dyes 1, 2 and 3. Furthermore, we have observed a strong induced CD (ICD) signal corresponding to the squaraine
chromophore in the case of the halogenated squaraine dyes 2 and 3 at 636 and 637 nm confirming the complex formation in these cases. To understand the nature of interaction of the squaraine dyes 1-3 with lysozyme, we have investigated the interaction of dyes 1-3 with different amino acids.
These results indicated that the dyes 1-3 showed significant interactions with cysteine and glutamic acid which are present in the side chains of lysozyme. In addition the temperature dependent studies have revealed that the interaction of the dye and the lysozyme are irreversible. Furthermore, we have investigated the interactions of these NIR dyes 1-3 with β- amyloid fibres derived from lysozyme to evaluate their potential as inhibitors of this biologically important protein aggregation. These β-amyloid fibrils were insoluble protein aggregates that have been associated with a range of neurodegenerative diseases, including Huntington, Alzheimer’s, Parkinson’s, and Creutzfeldt-Jakob diseases.
We have synthesized amyloid fibres from lysozyme through its incubation in acidic solution below pH 4 and by allowing to form amyloid fibres at elevated temperature. To quantify the binding affinities of the squaraine dyes 1-3 with β-amyloids, we have carried out the isothermal titration calorimetric (ITC) measurements. The association constants were determined and
are found to be 1.2 × 105, 3.6× 105 and 3.2 × 105 M-1 for the dyes, 1-3, respectively.
To gain more insights into the amyloid inhibiting nature of the squaraine dyes
under investigations, we have carried out thioflavin assay, CD, isothermal titration
calorimetry and microscopic analysis. The addition of the dyes 1-3 (5μM) led to the complete quenching in the apparent thioflavin fluorescence, thereby indicating the destabilization of β-amyloid fibres in the presence of the squaraine dyes. Further, the inhibition of the amyloid fibres by the squaraine dyes 1-3, has been evidenced though the DLS, TEM AFM and SAED, wherein
we observed the complete destabilization of the amyloid fibre and transformation of the fibre into spherical particles of ca. These results
demonstrate the fact that the squaraine dyes 1-3 can act as protein labeling agents as well as the inhibitors of the protein amyloidogenesis.
The last chapter of the thesis describes the synthesis and investigation of selfassembly as well as bio-imaging aspects of a few novel tetraphenylethene conjugates 4-6.Expectedly, these conjugates showed significant solvatochromism and exhibited a hypsochromic shift (negative
solvatochromism) as the solvent polarity increased, and these observations were
justified though theoretical studies employing the B3LYP/6-31g method.
We have investigated the self-assembly properties of these D-A conjugates
though variation in the percentage of water in acetonitrile solution due to the formation of nanoaggregates. Further the contour map of the observed fluorescence intensity as a function of the fluorescence excitation and emission wavelength confirmed the formation of J-type aggregates in these cases.
To have a better understanding of the type of self-assemblies formed from the
TPE conjugates 4-6, we have carried out the morphological analysis through various microscopic techniques such as DLS, SEM and TEM. 70%, we observed rod shape architectures having ~ 780 nm in diameter and ~ 12 μM in length as evidenced through TEM and SEM analysis.
We have made similar observations with the dodecyl conjugate 5 at ca. 70% and 50% water/acetonitrile mixtures, the aggregates formed from 4 and 5 were found to be highly crystalline and such structures were transformed to amorphous nature as the water fraction was increased to 99%. To evaluate the potential of the conjugate as bio-imaging agents, we have carried out their in vitro cytotoxicity and cellular uptake studies though MTT assay, flow cytometric and confocal laser scanning microscopic techniques. Thus nanoparticle of these conjugates which
exhibited efficient emission, large stoke shift, good stability, biocompatibility and
excellent cellular imaging properties can have potential applications for tracking cells as well as in cell-based therapies. In summary we have synthesized novel functional organic chromophores and have studied systematic investigation of self-assembly of these synthetic and biological building blocks under a variety of conditions. The investigation of interaction of water soluble NIR squaraine dyes with lysozyme indicates that these dyes can act as the protein labeling agents and the efficiency of inhibition of β-amyloid indicate, thereby their potential as anti-amyloid agents.