Fabrication and characterisation of polymer optical fibers for smart sensing and optical amplification

The thesis presented the fabrication and characterisation of polymer optical fibers in their applications as optical amplifier and smart sensors.Optical polymers such as PMMA are found to be a very good host material due to their ability to incorporate very high concentration of optical gain media like fluorescent dyes and rare earth compounds. High power and high gain optical amplification in organic dye-doped polymer optical fibers is possible due to extremely large emission cross sections of oyes. Dye doped (Rhodamine 6G) optical fibers were fabricated by using indigenously developed polymer optical fiber drawing tower. Loss characterization of drawn dye doped fibers was carried out using side illumination technique. The advantage of the above technique is that it is a nondestructive method and can also be used for studying the uniformity in fiber diameter and doping. Sensitivity of the undoped polymer fibers to temperature and microbending were also studied in its application in smart sensors.Optical amplification studies using the dye doped polymer optical fibers were carried out and found that an amplification of l8dB could be achieved using a very short fiber of length lOcm. Studies were carried out in fibers with different dye concentrations and diameter and it was observed that gain stability was achieved at relatively high dye concentrations irrespective of the fiber diameter.Due to their large diameter, large numerical aperture, flexibility and geometrical versatility of polymer optical fibers it has a wide range of applications in the field of optical sensing. Just as in the case of conventional silica based fiber optic sensors, sensing techniques like evanescent wave, grating and other intensity modulation schemes can also be efficiently utilized in the case of POF based sensors. Since polymer optical fibers have very low Young's modulus when compared to glass fibers, it can be utilized for sensing mechanical stress and strain efficiently in comparison with its counterpart. Fiber optic sensors have proved themselves as efficient and reliable devices to sense various parameters like aging, crack formation, weathering in civil structures. A similar type of study was carried out to find the setting characteristics of cement paste used for constructing civil structures. It was found that the measurements made by using fiber optic sensors are far more superior than that carried out by conventional methods. More over,POF based sensors were found to have more sensitivity as well.

A fiber optic smart sensor for studying the setting characteristics of various grades of cement

A simple, effective and inexpensive fiber optic sensor for investigating the setting characteristics of various grades of cement is described. A finite length of unsheathed multimode optical fiber laid inside the cement mix, is subjected to stress during the setting process. The microbends created on the fiber due to this stress directly influence the intensity of light propagating through the fiber. Continuous monitoring of such variations in the light output transmitted through the fiber gives a clear measure of the setting characteristics of the cement mix, thus providing a simple and elegant technique of great practical importance in the field of civil engineering. The smart fiber optic sensor described above can be incorporated into a building during the construction process itself so that continuous monitoring of the deterioration process for the entire life time of the building can be carried out.

Hydrogeochemical evaluation of inorganics and bioorganics in selected aquatic environments

The present study is an investigation to address relevant chemical aspects of the three varied aquatic environments, such as mangroves, river and the estuary. The sampling locations include a thick mangrove forest with high tidal activity, a mangrove nursery with minimal disturbances and low tidal inundation, a highly polluted riverine system and an estuarine site, as reference. Nutrients and bioorganic compounds in the water column and surface sediment were estimated in an attempt to understand the regeneration properties of these different aquatic systems.Assessment of the trace metal pollution was also carried out.

Characterization of polyhydroxyalkanoates accumulating vibrios from marine benthic environments and production studies of polyhydroxyalkanoates by Vibrio sp. BTKB33

The present work deals with the characterization of polyhydroxyalkanoates accumulating vibrios from marine benthic environments and production studies of polyhydroxyalkanoates by vibrio sp.BTKB33. Vibrios are a group of (iram negative, curved or straight motile rods that normally inhabit the aquatic environments.The present study therefore aimed at evaluating the occurrence of PHA accumulating vibrios inhabiting marine benthic environments; characterizing the potential PHA accumulators employing phenotypic and genotypic approaches and molecular characterization of the PHA synthase gene. The study also evaluated the PHA production in V:'hri0 sp. strain BTKB33, through submerged fennentation using statistical optimization and characterized the purified biopolymer. Screening for PHA producing vibrios from marine benthic environments. Characterization of PHA producers employing phenotypic and genotypic approaches.The incidence of PHA accumulation in Vibrio sp. isolated from marine sediments was observed to be high, indicating that the natural habitat of these bacteria are stressful. Considering their ubiquitous nature, the ecological role played by vibrios in maintaining the delicate balance of the benthic ecosystem besides returning potential strains, with the ability to elaborate a plethora of extracellular enzymes for industrial application, is significant. The elaboration of several hydrolytic enzymes by individuals also emphasize the crucial role of vibrios in the mineralization process in the marine environment. This study throws light on the extracellular hydrolytic enzyme profile exhibited by vibrios. It was concluded that apart from the PHA accumulation, presence of exoenzyme production and higher MAR index also aids in their survival in the highly challenging benthic enviromnents. The phylogenetic analysis of the strains and studies on intra species variation within PHA accumulating strains reveal their diversity. The isolate selected for production in this study was Vibrio sp. strain BTKB33, identified as V.azureus by 16S rDNA sequencing and phenotypic characterization. The bioprocess variables for PHA production utilising submerged fermentation was optimized employing one-factor-at-a-time-method, PB design and RSM studies. The statistical optimization of bioprocess variables revealed that NaCl concentration, temperature and incubation period are the major bioprocess variables influencing PHA production and PHA content. The presence of Class I PHA synthase genes in BTKB33 was also unveiled. The characterization of phaC genes by PCR and of the extracted polymer employing FTIR and NMR analysis revealed the presence of polyhydroxybutyrate, smallest known PI-IAs, having wider domestic, industrial and medical application. The strain BTKB33 bearing a significant exoenzyme profile, can thus be manipulatedin future for utilization of diverse substrates as C- source for PHA production. In addition to BTKB33, several fast growing Vibrio sp. having PHA accumulating ability were also isolated, revealing the prospects of this environment as a mine for novel PHA accumulating microbes. The findings of this study will provide a reference for further research in industrial production of PHAs from marine microorganisms .

Studies on The Ecophysiology Of Some Heterotrophic and Indicator Bacteria In The Marine Environments of Kerala

The thesis entitled "Studies on the eco-physiology of heterotrophic and indicator bacteria in the marine environments of Kerala" embodies the results of an investigation carried out by the candidate at the Central Marine Fisheries Research Institute, Cochin. It is presentedd under 4 chapters in two parts (Parts A & B) and includes 6 sections. The material for the study was collected in the Cochin backwater during April 1972 to February. 1973, March 1974 to February 1975, July 1975 to June 1976 and in the ishore area during January to October, 1978 and an account of the heterotropic and indicator bacteria are given with intensity charts and tables. Samples from all the stations contained significant quantities of heterotrophs (Part A, Section I) and faecal pollution indicators (Section II). Maximum number of heterotrophic bacteria was observed during the postmonsoon period. The total counts betwen one station and the other did not vary as much as the counts between months did. The distribution was characterised by overdispersion. During 1972-73 in all the stations except the fourth the minimum heterotrophs (Total counts) were recorded during the monsoon period. Minimum counts were observed during the premonsoon period, with an increasing trend from the premonsoon to postmonsoon seasons. Maximum counts were recorded during monsoon months during 1974-75. No significant difference was noted in the total plate count between stations, months and regions. Seasonal variations in sea water was meagre during 1975-76, whereas in sediments variations were prominent during monsoon in Station I - near the mouth of the sewage effluent of Cochin City and in postmonsoon at Station II in the Mattancherry Channel and Station III near barmouth

Studies on phytoplankton of the estuarine and marine environments

This thesis deals with the results oi’ investigations on phytoplankton productivity and related aspects conducted in various ecoaystms such as estuarine, inshore and oceanic enviroments and certain special ecosytans including the pu.-awn culture fields and associated many-eves, mud bank and the seas around the Andaman-Nicobar Islands. This study also includes the qualitative and quantitative variations of phytoplankton production, their seasonal abundance, factors controlling the same and the magnitude of the potential resources derived 1!:-om it

"Effects of some heavy metals copper. zinc and lead on certain tissues of £153 Qarsia (Hamilton and Buchanan) in different environments

The research investigations on pollution, particularly in coastal/ estuarine environments are recent ones and started only in 1970s. Hence the informations available are fragmentary and scattered. They throw some light only on either the concentration of heavy metals in water or in sediment or in organisms. No concerted efforts have been made to consolidate and correlate the results between the environment and biota. Literature on the level of concentration of heavy metals in different tissues of organisms with regard to their availability in the living media, their ratio, their inter—relationship, tolerance limit of organisms, etc. are very few or rather nil. in view of the importance enumerated above, the candidate has selected the topic "Effects of some heavy metals copper, zinc and lead on certain tissues of E E (Hamilton and Buchanan) in different environments" for detailed studies and to understand systematically (i) the source of effluents and wastes, (ii) the concentration of heavy metals copper, zinc and lead in water, in sediments and in tissues of the test animal, (iii) their effects, (iv) capacity of tolerance and accumulation in different tissues of the animal, and (V) the "Bioaccumulation Factor", etc.

THE SOCIAL ENVIRONMENTS IN HINDI LITERATURE OF BHAKTI PERIOD

HINDI

Characterization and Pathogenicity of Vibrio cholerae and Vibrio vulnificus from Marine environments

The genus Vibrioof the family Vibrionaceae are Gram negative, oxidasepositive, rod- or curved- rodshaped facultative anaerobes, widespread in marine and estuarine environments. Vibrio species are opportunistic human pathogens responsible for diarrhoeal disease, gastroenteritis, septicaemia and wound infections and are also pathogens of aquatic organisms, causing infections to crustaceans, bivalves and fishes. In the present study, marine environmental samples like seafood and water and sediment samples from aquafarms and mangroves were screened for the presence of Vibrio species. Of the134 isolates obtained from the various samples, 45 were segregated to the genus Vibrio on the basis of phenotypic characterization.like Gram staining, oxidase test, MoF test and salinity tolerance. Partial 16S rDNA sequence analysis was utilized for species level identification of the isolates and the strains were identified as V. cholerae(N=21), V. vulnificus(N=18), V. parahaemolyticus(N=3), V. alginolyticus (N=2) and V. azureus (N=1). The genetic relatedness and variations among the 45 Vibrio isolates were elucidated based on 16S rDNA sequences. Phenotypic characterization of the isolates was based on their response to 12 biochemical tests namely Voges-Proskauers’s (VP test), arginine dihydrolase , tolerance to 3% NaCl test, ONPG test that detects β-galactosidase activity, and tests for utilization of citrate, ornithine, mannitol, arabinose, sucrose, glucose, salicin and cellobiose. The isolates exhibited diverse biochemical patterns, some specific for the species and others indicative of their environmental source.Antibiogram for the isolates was determined subsequent to testing their susceptibility to 12 antibiotics by the disc diffusion method. Varying degrees of resistance to gentamycin (2.22%), ampicillin(62.22%), nalidixic acid (4.44%), vancomycin (86.66), cefixime (17.77%), rifampicin (20%), tetracycline (42.22%) and chloramphenicol (2.22%) was exhibited. All the isolates were susceptible to streptomycin, co-trimoxazole, trimethoprim and azithromycin. Isolates from all the three marine environments exhibited multiple antibiotic resistance, with high MAR index value. The molecular typing methods such as ERIC PCR and BOX PCR revealed intraspecies relatedness and genetic heterogeneity within the environmental isolatesof V. cholerae and V. vulnificus. The 21 strains of V. choleraewere serogroupedas non O1/ non O139 by screening for the presence O1rfb and O139 rfb marker genes by PCR. The virulence/virulence associated genes namely ctxA, ctxB, ace, VPI, hlyA, ompU, rtxA, toxR, zot, nagst, tcpA, nin and nanwere screened in V. cholerae and V. vulnificusstrains.The V. vulnificusstrains were also screened for three species specific genes viz., cps, vvhand viu. In V. cholerae strains, the virulence associated genes like VPI, hlyA, rtxA, ompU and toxR were confirmed by PCR. All the isolates, except for strain BTOS6, harbored at least one or a combination of the tested genes and V. choleraestrain BTPR5 isolated from prawn hosted the highest number of virulence associated genes. Among the V. vulnificusstrains, only 3 virulence genes, VPI, toxR and cps, were confirmed out of the 16 tested and only 7 of the isolates had these genes in one or more combinations. Strain BTPS6 from aquafarm and strain BTVE4 from mangrove samples yielded positive amplification for the three genes. The toxRgene from 9 strains of V. choleraeand 3 strains of V. vulnificus were cloned and sequenced for phylogenetic analysis based on nucleotide and the amino acid sequences. Multiple sequence alignment of the nucleotide sequences and amino acid sequences of the environmental strains of V. choleraerevealed that the toxRgene in the environmental strains are 100% homologous to themselves and to the V. choleraetoxR gene sequence available in the Genbank database. The 3 strains of V. vulnificus displayed high nucleotide and amino acid sequence similarity among themselves and to the sequences of V. cholerae and V. harveyi obtained from the GenBank database, but exhibited only 72% homology to the sequences of its close relative V. vulnificus. Structure prediction of the ToxR protein of Vibrio cholerae strain BTMA5 was by PHYRE2 software. The deduced amino acid sequence showed maximum resemblance with the structure of DNA-binding domain of response regulator2 from Escherichia coli k-12 Template based homology modelling in PHYRE2 successfully modelled the predicted protein and its secondary structure based on protein data bank (PDB) template c3zq7A. The pathogenicity studies were performed using the nematode Caenorhabditiselegansas a model system. The assessment of pathogenicity of environmental strain of V. choleraewas conducted with E. coli strain OP50 as the food source in control plates, environmental V. cholerae strain BTOS6, negative for all tested virulence genes, to check for the suitability of Vibrio sp. as a food source for the nematode;V. cholerae Co 366 ElTor, a clinical pathogenic strain and V. cholerae strain BTPR5 from seafood (Prawn) and positive for the tested virulence genes like VPI, hlyA, ompU,rtxA and toxR. It was found that V. cholerae strain BTOS6 could serve as a food source in place of E. coli strain OP50 but behavioral aberrations like sluggish movement and lawn avoidance and morphological abnormalities like pharyngeal and intestinal distensions and bagging were exhibited by the worms fed on V. cholerae Co 366 ElTor strain and environmental BTPR5 indicating their pathogenicity to the nematode. Assessment of pathogenicity of the environmental strains of V. vulnificus was performed with V. vulnificus strain BTPS6 which tested positive for 3 virulence genes, namely, cps, toxRand VPI, and V. vulnificus strain BTMM7 that did not possess any of the tested virulence genes. A reduction was observed in the life span of worms fed on environmental strain of V. vulnificusBTMM7 rather than on the ordinary laboratory food source, E. coli OP50. Behavioral abnormalities like sluggish movement, lawn avoidance and bagging were also observed in the worms fed with strain BTPS6, but the pharynx and the intestine were intact. The presence of multi drug resistant environmental Vibrio strainsthat constitute a major reservoir of diverse virulence genes are to be dealt with caution as they play a decisive role in pathogenicity and horizontal gene transfer in the marine environments.

Smart electricity networks based on large integration of renewable sources and distributed generation

Das Grünbuch 2006 der Europäischen Kommission "Eine Europäische Strategie für nachhaltige, wettbewerbsfähige und sichere Energie" unterstreicht, dass Europa in ein neues Energie-Zeitalter eingetreten ist. Die vorrangigen Ziele europäischer Energiepolitik müssen Nachhaltigkeit, Wettbewerbsfähigkeit und Versorgungssicherheit sein, wobei sie eine zusammenhängende und logische Menge von Taktiken und Maßnahmen benötigt, um diese Ziele zu erreichen. Die Strommärkte und Verbundnetze Europas bilden das Kernstück unseres Energiesystems und müssen sich weiterentwickeln, um den neuen Anforderungen zu entsprechen. Die europäischen Stromnetze haben die lebenswichtigen Verbindungen zwischen Stromproduzenten und Verbrauchern mit großem Erfolg seit vielen Jahrzehnten gesichert. Die grundlegende Struktur dieser Netze ist entwickelt worden, um die Bedürfnisse großer, überwiegend auf Kohle aufgebauten Herstellungstechnologien zu befriedigen, die sich entfernt von den Verbraucherzentren befinden. Die Energieprobleme, denen Europa jetzt gegenübersteht, ändern die Stromerzeugungslandschaft in zwei Gesichtspunkten: die Notwendigkeit für saubere Kraftwerkstechnologien verbunden mit erheblich verbesserten Wirkungsgraden auf der Verbraucherseite wird es Kunden ermöglichen, mit den Netzen viel interaktiver zu arbeiten; andererseits müssen die zukünftigen europaweiten Stromnetze allen Verbrauchern eine höchst zuverlässige, preiswerte Energiezufuhr bereitstellen, wobei sowohl die Nutzung von großen zentralisierten Kraftwerken als auch kleineren lokalen Energiequellen überall in Europa ausgeschöpft werden müssen. In diesem Zusammenhang wird darauf hingewiesen, dass die Informationen, die in dieser Arbeit dargestellt werden, auf aktuellen Fragen mit großem Einfluss auf die gegenwärtigen technischen und wirtschaftspolitischen Diskussionen basieren. Der Autor hat während der letzten Jahre viele der hier vorgestellten Schlussfolgerungen und Empfehlungen mit Vertretern der Kraftwerksindustrie, Betreibern von Stromnetzen und Versorgungsbetrieben, Forschungsgremien und den Regulierungsstellen diskutiert. Die folgenden Absätze fassen die Hauptergebnisse zusammen: Diese Arbeit definiert das neue Konzept, das auf mehr verbraucherorientierten Netzen basiert, und untersucht die Notwendigkeiten sowie die Vorteile und die Hindernisse für den Übergang auf ein mögliches neues Modell für Europa: die intelligenten Stromnetze basierend auf starker Integration erneuerbarer Quellen und lokalen Kleinkraftwerken. Das neue Modell wird als eine grundlegende Änderung dargestellt, die sich deutlich auf Netzentwurf und -steuerung auswirken wird. Sie fordert ein europäisches Stromnetz mit den folgenden Merkmalen: – Flexibel: es erfüllt die Bedürfnisse der Kunden, indem es auf Änderungen und neue Forderungen eingehen kann – Zugänglich: es gestattet den Verbindungszugang aller Netzbenutzer besonders für erneuerbare Energiequellen und lokale Stromerzeugung mit hohem Wirkungsgrad sowie ohne oder mit niedrigen Kohlendioxidemissionen – Zuverlässig: es verbessert und garantiert die Sicherheit und Qualität der Versorgung mit den Forderungen des digitalen Zeitalters mit Reaktionsmöglichkeiten gegen Gefahren und Unsicherheiten – Wirtschaftlich: es garantiert höchste Wirtschaftlichkeit durch Innovation, effizientes Energiemanagement und liefert „gleiche Ausgangsbedingungen“ für Wettbewerb und Regulierung. Es beinhaltet die neuesten Technologien, um Erfolg zu gewährleisten, während es die Flexibilität behält, sich an weitere Entwicklungen anzupassen und fordert daher ein zuversichtliches Programm für Forschung, Entwicklung und Demonstration, das einen Kurs im Hinblick auf ein Stromversorgungsnetz entwirft, welches die Bedürfnisse der Zukunft Europas befriedigt: – Netztechnologien, die die Stromübertragung verbessern und Energieverluste verringern, werden die Effizienz der Versorgung erhöhen, während neue Leistungselektronik die Versorgungsqualität verbessern wird. Es wird ein Werkzeugkasten erprobter technischer Lösungen geschaffen werden, der schnell und wirtschaftlich eingesetzt werden kann, so dass bestehende Netze Stromeinleitungen von allen Energieressourcen aufnehmen können. – Fortschritte bei Simulationsprogrammen wird die Einführung innovativer Technologien in die praktische Anwendung zum Vorteil sowohl der Kunden als auch der Versorger stark unterstützen. Sie werden das erfolgreiche Anpassen neuer und alter Ausführungen der Netzkomponenten gewährleisten, um die Funktion von Automatisierungs- und Regelungsanordnungen zu garantieren. – Harmonisierung der ordnungspolitischen und kommerziellen Rahmen in Europa, um grenzüberschreitenden Handel von sowohl Energie als auch Netzdienstleistungen zu erleichtern; damit muss eine Vielzahl von Einsatzsituationen gewährleistet werden. Gemeinsame technische Normen und Protokolle müssen eingeführt werden, um offenen Zugang zu gewährleisten und den Einsatz der Ausrüstung eines jeden Herstellers zu ermöglichen. – Entwicklungen in Nachrichtentechnik, Mess- und Handelssystemen werden auf allen Ebenen neue Möglichkeiten eröffnen, auf Grund von Signalen des Marktes frühzeitig technische und kommerzielle Wirkungsgrade zu verbessern. Es wird Unternehmen ermöglichen, innovative Dienstvereinbarungen zu benutzen, um ihre Effizienz zu verbessern und ihre Angebote an Kunden zu vergrößern. Schließlich muss betont werden, dass für einen erfolgreichen Übergang zu einem zukünftigen nachhaltigen Energiesystem alle relevanten Beteiligten involviert werden müssen.

Untersuchungen zu Fabry-Pérot Filterfeldern: Herstellung mittels Nanoimprinttechnologie, experimentelle Charakterisierung und Anwendungen

Die spektrale Zusammensetzung von Licht ändert sich, wenn es mit gasförmiger, flüssiger oder fester Materie d.h. mit Ionen, Atomen, Molekülen, Atom- und Molekülverbänden und amorphen oder kristallinen Festkörpern interagiert. Spektroskopische Messungen des Lichts nach der Wechselwirkung geben Aufschluss über die Eigenschaften der zu untersuchenden Materie [2]. Viele der heute noch nicht realisierbaren Ideen und Konzepte in den verschiedensten Anwendungsfeldern der Sensorik benötigen aber für ihre Umsetzung extrem miniaturisierte Spektrometer als Kernbestandteil der Sensoren. Ziel ist es jedoch nicht, dem Anwender dieser Sensoren Informationen über das Spektrum zu liefern, sondern die ausgewerteten spektralen Information als Indikator zum Handeln zu nutzen. Derartige intelligente Sensoren werden in Zukunft unter anderem dazu beitragen intelligente persönliche Umgebungen (engl.: smart rooms, smart buildings, smart cities, samrt personal environments) zu entwerfen und zu realisieren. Grundvoraussetzung für die Erschließung der verschiedenen Anwendungsgebiete sind Spektrometer, die die Anforderungen an niedrige Kosten, hohe Stückzahlen sowie geringe Größe und geringes Gewicht besser als verfügbare Hochleistungsgitter-Spektrometer erfüllen, die zwar bereits in den Bereich weniger Zentimeter miniaturisiert wurden, aber immer noch makroskopisch sind. Ziel dieser Arbeit ist es, zu zeigen, dass es möglich ist, ein Fabry-Pérot Filterfeld herzustellen, welches später den Kern eines Nanospektrometers darstellen soll, bei dem die unterschiedlichen Kavitäten in einem einzigen Schritt mithilfe der Nanoimprint-Technologie erzeugt werden. Angesichts des Forschungsdefizits hinsichtlich der Nutzung der Nanoimprint-Technologie zur Fertigung von in ihrer Höhe exakten Strukturen werden in der vorliegenden Arbeit zwei Nanoimprint-Technologien untersucht: Das Heißprägen und das UV-Prägen. Das Ergebnis dieser Arbeit ist ein Fabry-Pérot Filterfeld, welches mittels geeigneter Nanoimprint-Technologie hergestellt wurde und demonstriert, dass ein Nanospektrometer auf der Basis eines Feldes von Filtern technisch realisierbar ist. Dazu werden im praktischen Teil dieser Arbeit (Untersuchung der Prägeprozesse) verschiedene technologische Methoden und Maschinen vorgestellt und die damit erreichten Ergebnisse hinsichtlich der Fabry-Pérot-Filterfelder verglichen. Die hergestellten Filterfelder wurden systematisch spektral vermessen. Diese Analyse zeigt 64 Transmissionsbänder der einzelnen Filter eines Feldes. Ein Vergleich mit publizierten Arbeiten des Standes der Wissenschaft und Technik zeigt, dass im Rahmen der vorliegenden Arbeit eine deutliche Verbesserung erreicht wurde. So konnte eine drastische Steigerung der transmittierten Lichtintensität der Filter erzielt werden und eine Nanoimprint-Methode identifiziert werden, mit welcher es möglich ist, einen Demonstrator herzustellen. Aufgrund der im Rahmen einer ausführlichen Charakterisierung ermittelten sehr guten experimentellen Ergebnisse des Demonstrators kann ein Nanospektrometer mit dem Fabry-Pérot-Filterfeld als Kernbestandteil in Zukunft hergestellt werden.