Unsaturated polyester resins (UPRs) are extensively
used by the fiber-reinforced plastic (FRPs) industry.
These resins have the disadvantages of brittleness and
poor resistance to crack propagation. In this study, UPRs
were chemically modified by reactive blending with polyurethane
prepolymers having terminal isocyanate groups.
Hybrid networks were formed by copolymerisation of unsaturated
polyesters with styrene and simultaneous reaction
between terminal hydroxyl groups of unsaturated polyester
and isocyanate groups of polyurethane prepolymer. The
prepolymers were based on toluene diisocyanate (TDI) and
each of hydroxy-terminated natural rubber (HTNR), hydroxy-
terminated polybutadiene (HTPB), polyethylene glycol
(PEG), and castor oil. Properties like tensile strength,
toughness, impact resistance, and elongation-at-break of the
modified UPRs show considerable improvement by this
modification. The thermal stability of the copolymer is also
marginally better
Description:
Journal of Applied Polymer Science, Vol. 100, 449–456 (2006)
Pravinkumar,P A; Dr.Nair, K G(Cochin University of Science and Technology, March 18, 1985)
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Abstract:
With the advent of satellite communication and radio astronomy, the need for large and efficient reflector antennas had triggered a widespread investigation in reflector feed design techniques. Major improvements sought are reduction in spill-over, cross polarization losses and the enhancement of aperture efficiency. The search for such a feed culminated in the corrugated horn. The main idea behind the present work is to use the H-plane sectoral horns fitted with,corrugated flanges as feeds of a paraboloid and see how the secondary pattern
of the reflector antenna varies with different parameters of the feed. An offset paraboloid is used as the secondary reflector in order to avoid the adverse effect of aperture ‘blocking by the feed horn structure on the secondary radiation pattern. The measurements were repeated for three
different H-plane sectoral horns with the same set of corrugated flanges at various X-band frequencies. The following parameters of the whole system are studied: (a) Beam shaping. (b) Gain. (c) Variation of VSWR and (d) Cross polarization
Description:
Department of Physics, Cochin University of Science and Technology
Tessamma, Thomas; Dr.Sridhar, C S(Cochin University Of Science And Technology, August 24, 1993)
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Abstract:
This thesis investigated the potential use of Linear Predictive
Coding in speech communication applications. A Modified Block Adaptive
Predictive Coder is developed, which reduces the computational burden and
complexity without sacrificing the speech quality, as compared to the
conventional adaptive predictive coding (APC) system. For this, changes in
the evaluation methods have been evolved. This method is as different from
the usual APC system in that the difference between the true and the
predicted value is not transmitted. This allows the replacement of the high
order predictor in the transmitter section of a predictive coding system, by
a simple delay unit, which makes the transmitter quite simple. Also, the
block length used in the processing of the speech signal is adjusted
relative to the pitch period of the signal being processed rather than
choosing a constant length as hitherto done by other researchers. The
efficiency of the newly proposed coder has been supported with results of
computer simulation using real speech data.
Three methods for voiced/unvoiced/silent/transition
classification have been presented. The first one is based on energy,
zerocrossing rate and the periodicity of the waveform. The second method
uses normalised correlation coefficient as the main parameter, while the
third method utilizes a pitch-dependent correlation factor. The third
algorithm which gives the minimum error probability has been chosen in a
later chapter to design the modified coder The thesis also presents a comparazive study beh-cm the
autocorrelation and the covariance methods used in the evaluaiicn of the
predictor parameters. It has been proved that the azztocorrelation method is
superior to the covariance method with respect to the filter stabf-it)‘ and
also in an SNR sense, though the increase in gain is only small. The
Modified Block Adaptive Coder applies a switching from pitch precitzion to
spectrum prediction when the speech segment changes from a voiced or
transition region to an unvoiced region. The experiments cont;-:ted in
coding, transmission and simulation, used speech samples from .\£=_‘ajr2_1a:r1
and English phrases. Proposal for a speaker reecgnifion syste: and a
phoneme identification system has also been outlized towards the end of
the thesis.
Description:
Department of Electronics, Cochin University of Science and
Technology
Dey,S; Aanandan,C K; Mohanan, P; K G Nair(Department of Electronics, June , 1993)
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Abstract:
A circular miqrostrip antenna with a modified structure is
presented. By adjusting the feed location along the circumference
of the patch it is possible to match the antenna with a C
microstrip line of any impedance. The impedance bandwidth
and radiation characteristics are unaffected by this structural
V modification.
The influence of the chemical composition and silylation of mesoporous MCM-41 materials on the photochromic
behaviour of adsorbed spiropyran (BIPS) and 6-nitrospiropyran was studied. Upon incorporation, the spiropyrans
underwent ring opening to form either zwitterionic merocyanine or its corresponding O-protonated form. In all
silica MCM-41 or in the MCM-41 containing aluminium, the O-protonated merocyanine was predominantly
formed. In the case of MCM-41 modified by silylation of the OH groups, a mixture of zwitterionic merocyanine
and spiropyran was present. The photochromic response was studied by means of steady-state irradiation and by
laser flash photolysis. Steady-state irradiation (λ > 450 nm) of the solid samples gives rise in all cases to an intensity
decrease of the absorption bands corresponding to either the protonated or the unprotonated merocyanine form
(reverse photochromism). In contrast, laser flash photolysis at 308 nm of spiropyrans supported on silylated
MCM-41 allows observation of the photochemical ring opening of residual spiropyran to the corresponding
zwitterionic form (normal photochromism).
Afsal, V V; Dr Rosamma Philip(Cochin University of Science and Technology, June 9, 2015)
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Abstract:
Most living organisms are constantly exposed to potentially harmful pathogens. It is the immune system of the organism that enables it to survive in an environment loaded with dangerous pathogenic microorganisms. The innate immunity provides organisms with a rapid and non-specific first line of defense against pathogens. It includes physical barriers such as skin and mucous membranes and chemical barriers including the high acidity of gastric juice, and specialized soluble molecules that possess antimicrobial activity. One of the well-known innate immune defense mechanisms is the production of antimicrobial substances by specific cells or tissues of the organisms. Antimicrobial peptides (AMPs) are such natural substances that
Naveen Sathyan; Dr. Rosamma Philip(Cochin University of Science and Technology, May 5, 2015)
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Abstract:
Antimicrobial peptides (AMPs) are gene encoded, small sized, generally cationic, amphiphathic peptides characterized by antimicrobial activity against bacteria, fungi, viruses and other pathogens. They are a major component of the innate immune defense system of almost all living organisms, ranging from bacteria to humans and represent the first line of defense against the invading microbial pathogens (Boman, 1995; Zasloff, 2002). Antimicrobial peptides represent a heterogeneous group displaying multiple modes of action that are determined by the sequence and concentration of peptides. Their remarkable specificity for prokaryotes with low toxicity for eukaryotic cells has favored their investigation and exploitation as new antibiotics
Sreelakshmi, B; Dr.Bright Singh,I S(Cochin University Of Science And Technology, November , 2011)
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Abstract:
The present study focuses on vibrios especially Vibrio harveyi
isolated from shrimp (P. monodon) larval production systems from both east
and west coasts during times of mortality. A comprehensive approach has
been made to work out their systematics through numerical taxonomy and
group them based on RAPD profiling and to segregate the virulent from
non- virulent isolates based on the presence of virulent genes as well as their
phenotypic expression. The information gathered has helped to develop a
simple scheme of identification based on phenotypic characters and
segregate the virulent from non virulent strains of V. harveyi.
Description:
National Centre for Aquatic Animal Health
Cochin University of Science and
Technology
Toms C, Joseph; Dr.Surendran, P K; Dr. Nirmala, Thampuran(Central Institute of Fisheries Technology, January , 2010)
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Abstract:
This thesis covers various aspects of viral diseases affecting shrimp aquaculture. The
research component of this thesis can be divided into four areas. The areas covered are: I) A
study to determine the prevalence of WSSV among the crustaceans in the Vembanad estuary, the
shrimp aquaculture farms surrounding the estuary, and the sea off Cochin coast, India using two
, sets of nested PCR primers. 2) An investigation to compare the sequence of six major structural
proteins of WSSV; vp28, vp26, vp 19, vp68, vp281, vp466 from different geographical locations
with that of an isolate from India. 3) Simultaneous occurrence of HPV, IHHNV, MBV and
WSSV in postlarvae of P. monodon from hatcheries in India was monitored by Polymerase
Chain Reaction. 4) A real time PCR procedure was developed for the quantitative analysis of
WSSV infection. The viral load of postlarvae from hatcheries in Kerala meant for aquaculture
was also determined using the quantitative PCR.
Thomas, K T; Dr.Mathew, N M(Cochin University of Science and Technology, April 22, 1997)
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Abstract:
The forms of natural rubber studied were sheet [RSS 4 and RSS 5], ISNR 20 and EBC. In the case of the latter two forms samples from estate and nonestate sectors were included. The samples were collected from different locations at specified intervals, for a particular period. The effect of the extent of mastication on raw rubber properties as well as the properties of the compounds and vulcanizates also studied. The consistency in raw rubber properties and breakdown behavior of skim rubber were studied by collecting samples periodically from selected processing units. The effect of incorporation of skim with
ISNR 20 has also been investigated
Description:
Rubber Research Institute of India
Rubber Board, Kottayam
Bright Singh, I S; Rosamma, Philip; Chaithanya, E R; Anil Kumar, P R; Sherine, Sonia Cubelio; Naveen, Sathyan(Springer, May 23, 2013)
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Abstract:
Hepcidin is a family of short cysteine-rich
antimicrobial peptides (AMPs) participating in various
physiological functions with inevitable role in host immune
responses. Present study deals with identification and
characterisation of a novel hepcidin isoform from coral fish
Zanclus cornutus. The 81 amino acid (aa) preprohepcidin
obtained from Z. cornutus consists of a hydrophobic aa rich
22 mer signal peptide, a highly variable proregion of 35 aa
and a bioactive mature peptide with 8 conserved cysteine
residues which contribute to the disulphide back bone. The
mature hepcidin, Zc-hepc1 has a theoretical isoelectric
point of 7.46, a predicted molecular weight of 2.43 kDa
and a net positive charge of ?1. Phylogenetic analysis
grouped Z. cornutus hepcidin with HAMP2 group hepcidins
confirming the divergent evolution of hepcidin-like
peptide in fishes. Zc-hepc1 can attain a b-hairpin-like
structure with two antiparallel b-sheets. This is the first
report of an AMP from the coral fish Z. cornutus.
Description:
Probiotics & Antimicro. Prot. (2013) 5:187–194
DOI 10.1007/s12602-013-9139-x
Swapna, Antony P; Dr.Rosamma,Philip(Cochin University of Science and Technology, March , 2011)
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Abstract:
The constitutive production of AMPs in shrimps ensures that animals
are able to protect themselves from low-level assaults by pathogens present
in the environment. As these molecules play important roles in the shrimp
immune defense system, the expression level of these AMPs are possible
indicators of the immune state of shrimps. The present study also indicates
the antiviral property of AMPs, especially ALF, stressing the importance of
their up-regulation through the application of immunostimulants/probiotics
as a prophylactic strategy in aquaculture. The present study shows that
shrimp defense system is equipped enough to evade WSSV infection to a
certain extent, when the animals were maintained on marine yeast and
probiotic diet, whereas the control diet fed group succumbed to WSSV
infection. This study reveals that marine yeast and probiotic supplemented
diet can delay the process of WSSV infection and confer greater protection to
the animals. Particularly, the protection conferred by marine yeast, C.
haemulonii S27 and Bacillus MCCB101 were highly promising imparting
greater hope to the aquaculture community to overcome the prevailing
disease problems in aquaculture. It may be inferred from the present study
that up-regulation of AMP genes could be effected by the application of
immunostimulants and probiotics. Also, AMP expression profile could be
used as an effective tool for screening immunostimulants and probiotics for application in shrimp culture. Ultimately, it is likely that no single
compound or strategy will provide a solution to the problem of disease
within aquaculture and that, in reality, a suite of techniques will be required
including the manipulation of the rearing environment, addition of
probionts as a matter of routine during culture, and the use of
immunostimulants and other supplements during vulnerable growth phases.
Finally, the development of good management practices, the control of
environmental variables, genetic improvement in the penaeid species,
understanding of host-virus interaction, modulation of the shrimp immune
system, supported by functional genomics and proteomics of this crustacean,
as a whole suggests that the control of WSSV is not far.
Description:
Department of Marine Biology, Microbiology and Biochemistry,
School of Marine Sciences, Cochin University of Science and Technology
Bright Singh, I S; Rosamma, Philip; Swapna, Antony P(Elsevier, June 23, 2011)
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Abstract:
Antimicrobial peptides (AMPs) play a major role in innate immunity. Penaeidins are a family of AMPs that
appear to be expressed in all penaeid shrimps. Penaeidins are composed of an N-terminal proline-rich
domain, followed by a C-terminal domain containing six cysteine residues organized in two doublets. This
study reports the first penaeidin AMP sequence, Fi-penaeidin (GenBank accession number HM243617) from
the Indian white shrimp, Fenneropenaeus indicus. The full length cDNA consists of 186 base pairs encoding 61
amino acidswith an ORF of 42 amino acids and contains a putative signal peptide of 19 amino acids. Comparison
of F. indicus penaeidin (Fi-penaeidin) with other known penaeidins showed that it shared maximum similarity
with penaeidins of Farfantepenaeus paulensis and Farfantepenaeus subtilis (96% each). Fi-penaeidin has a predicted
molecular weight (MW) of 4.478 kDa and theoretical isoelectric point (pI) of 5.3
Bright Singh, I S; Swapna, Antony P; Sudheer, N S; Vrinda, S; Priyaja, P; Rosamma, Philip(Elsevier, May 20, 2010)
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Abstract:
A crustinlike
antimicrobial peptide from the haemocytes of giant tiger shrimp, Penaeus monodon was
partially characterized at the molecular level and phylogenetic analysis was performed. The partial coding
sequence of 299 bp and 91 deduced amino acid residues possessed conserved cysteine residues characteristic
of the shrimp crustins. Phylogenetic tree and sequence comparison clearly confirmed divergence
of this crustinlike
AMP from other shrimp crustins. The differential expression of the crustinlike
AMP
in P. monodon in response to the administration of various immunostimulants viz., two marine yeasts
(Candida haemulonii S27 and Candida sake S165) and two bglucan
isolates (extracted from C. haemulonii
S27 and C. sake S165) were noted during the study. Responses to the application of two grampositive
probiotic bacteria (Bacillus MCCB101 and Micrococcus MCCB104) were also observed. The immune profile
was recorded preand
postchallenge
white spot syndrome virus (WSSV) by semiquantitative
RTPCR.
Expressions of seven WSSV genes were also observed for studying the intensity of viral infection in
the experimental animals. The crustinlike
AMP was found to be constitutively expressed in the animal
and a significant downregulation
could be noted postchallenge
WSSV. Remarkable downregulation
of the gene was observed in the immunostimulant fed animals prechallenge
followed by a significant
upregulation
postchallenge
WSSV. Tissuewise
expression of crustinlike
AMP on administration of C.
haemulonii and Bacillus showed maximum transcripts in gill and intestine. The marine yeast, C. haemulonii
and the probiotic bacteria, Bacillus were found to enhance the production of crustinlike
AMP and
confer significant protection to P. monodon against WSSV infection
Bright Singh, I S; Rosamma, Philip; Vrinda, Sukumaran; Cini, Achuthan; Rejish Kumar, V J; Valsamma, Joseph(Elsevier, February 10, 2013)
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Abstract:
The addition of commercial nitrifying bacterial products has resulted in significant improvement of
nitrification efficiency in recirculating aquaculture systems (RAS). We developed two nitrifying bacterial
consortia (NBC) from marine and brackish water as start up cultures for immobilizing commercialized
nitrifying bioreactors for RAS. In the present study, the community compositions of the NBC were
analyzed by universal 16S rRNA gene and bacterial amoA gene sequencing and fluorescence in situ
hybridization (FISH). This study demonstrated that both the consortia involved autotrophic nitrifiers,
denitrifiers as well as heterotrophs. Abundant taxa of the brackish water heterotrophic bacterial isolates
were Paenibacillus and Beijerinckia spp. whereas in the marine consortia they were Flavobacterium,
Cytophaga and Gramella species. The bacterial amoA clones were clustered together with high similarity
to Nitrosomonas sp. and uncultured beta Proteobacteria. FISH analysis detected ammonia oxidizers
belonging to b subclass of proteobacteria and Nitrosospira sp. in both the consortia, and Nitrosococcus
mobilis lineage only in the brackish water consortium and the halophilic Nitrosomonas sp. only in the
marine consortium. However, nitrite oxidizers, Nitrobacter sp. and phylum Nitrospira were detected in
both the consortia. The metabolites from nitrifiers might have been used by heterotrophs as carbon and
energy sources making the consortia a stable biofilm.
Description:
International Biodeterioration & Biodegradation 78 (2013) 74e81