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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Analýza kurýrních služeb v ČR

Jakimova, Julia January 2007 (has links)
Vlivy a přínosy expresní přepravy na rozvoj ekonomiky a na proces globalizace. Analýza mezinárodních expresních kurýrních společností přítomných na českém trhu. Porovnání kvality a rozsahu jimi nabízených služeb.
32

Analýza komunikační strategie uvnitř společnosti TNT Express spojené se změnou identity značky / Analysis of communication strategy within the company TNT Express related to the change of brand identity

Zezulka, Vojtěch January 2015 (has links)
The objective of this thesis is to analyze the communication strategy within TNT Express and its critical evaluation. The theoretical part is devoted to marketing and its tools, the brand and its importance and corporate identity and its ingredients. I introduce the company TNT Express and its strategy in the practical part. It is followed by the SWOT analysis. Then I analyze various communication activities related to the change of the brand identity. Based on identified problems that have arisen with the change in the company I will propose their solution.
33

Analysis of TNT, DNA Methylation, and Hair Pigmentation via Gas Chromatography-Mass Spectrometry and Spectroscopic Techniques

Ruchti, Jacqueline 08 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI)
34

Reduction of 2,4,6-Trinitrotoluene with Nanoscale Zero-Valent Iron

Welch, Regan Eileen 28 August 2007 (has links)
No description available.
35

Development and Application of Non-Traditional Vertebrate Models to Investigate Terrestrial Ecological Risk to 2,46-Trinitrotoluene Exposure

Johnson, Mark Steven 11 January 1999 (has links)
Assessing ecological risk to wildlife exposed to anthropogenic contamination in soil has traditionally been problematic. Attempts to standardize an approach to evaluate risk for various community types in North America have been challenging, given the variation in terrestrial communities and the values in which policy makers are bound to protect. This has resulted in vague, yet flexible guidance from the U.S. Environmental Protection Agency and other interested parties (e.g., the U.S. Army Corps of Engineers, and the Tri-Service Ecological Risk Assessment Working Group). Interpretation of these and other guidance has been variable, often resulting in conflicting opinions on how best to address the question of ecological risk to receptors that are exposed to xenobiotics in a soil matrix. This work reports the results of research designed to address the question of ecological risk to terrestrial vertebrates. Objective, ecologically-relevant criteria were used in the selection and development of models in this research. Several lines of logic were considered: 1) substance sensitivity, 2) ecological sensitivity (i.e., the species importance to the system; e.g., keystone species); and, 3) probability and extent of exposure. A primary soil contaminant at many U.S. Army installations is 2,4,6-trinitrotoluene (TNT). This was a result of the mass manufacturing, storing, and assembly of weapons from the early 1900's until the 1950s. The Army has reported soil concentrations of TNT ranging from 0.12 to 38,600 ug/g (Walsh and Jenkins 1992) and 0.08 to 64,000 ug/g (Hovatter et al. 1997). The chemical-physical properties of TNT result in a relatively unique compound, not easily amenable to current modeling techniques to estimate exposure to terrestrial wildlife. Moreover, there are few data describing the effects of exposure to TNT in other than mammals, fish, and specific invertebrates. In this research, the pathways of exposure and selected potential toxic effects from TNT exposure were investigated in a terrestrial salamander: Ambystoma tigrinum (tiger salamanders). A. tigrinum was chosen since they are exclusively carnivorous, relatively long-lived, have a thin integument, and are large enough to investigate individual effects. These investigations were designed to mimic natural conditions as closely as possible, though maintain a degree of homogeneity in a laboratory environment. All studies exposed salamanders to soil and food (earthworms) in identical preparations. As such, these exposures were considered complete, eliminating assumptions made regarding daily food consumption, systemic dermal dose, etc. The first study examined the relative contribution of dermal or oral exposures to the whole-body burdens of TNT and primary metabolites. A poly-chlorinated biphenyl (PCB) mixture (Aroclor7 1260) was used with TNT to simultaneously to assist in the evaluation of each pathway, since the fate and transport of PCBs are well characterized. Tiger salamanders were exposed 28 days in situ. The dermal route of exposure contributed the most to the final burdens of TNT in salamanders, with the primary reduction products, 2-amino-4,6-dinitrotoluene and 4-amino, 2,6-dinitrotoulene reaching higher concentrations than of parent compound. Other TNT metabolites were found in insignificant quantities. The concentrations of PCBs were higher in the oral treatment, as expected. These results were corroborated in a subsequent study using Ambystoma maculatum (spotted salamanders). The second series of investigations evaluated the potential toxic effects from TNT exposure. Two treatments consisting of TNT and a control were used to evaluate these effects to A. tigrinum. The salamanders were exposed in situ for 14 days to TNT in soil and food (earthworms of which were exposed to TNT in the soil in similar preparations). Non-specific immune effects were evaluated through the characterization of splenic phagocytes in their ability to: 1) phagocytize foreign particles, and 2) digest (through oxygen radicals) phagocytized material. This was conducted using fluorescent microspheres and a fluorescent chemical probe specific to hydrogen peroxide, measured per each cell using flow cytometry. Other data collected included histological examination (e.g., liver, kidney, and other miscellaneous organs), blood differentials, weight changes over time, organ/ body weight comparisons, and an analysis of organ-specific metabolism. No significant effects were noted in salamanders exposed to these conditions. Coordinated with the preceding study included a search for biomarkers of exposure and an investigation of the metabolites of TNT in situ. Biotransformation products of TNT were found including primary (e.g., 2-amino-4,6-dinitrotoluene) and secondary (e.g., 2,4-diamino-6-nitrotoluene) in relative concentrations in skin, liver, and kidney. Biomarkers of exposure included an analysis of cytochrome p450, b5, and the glutathione antioxidant enzymes in liver, kidney, skin, lung, and serum, respectively. Traces of parent compound were found in the skin and liver only. Levels of 2,4-diamino-6-nitrotoluene were found only in the liver and kidney, suggesting that TNT is reduced primarily in or on the skin. Levels of p450 were higher in TNT exposed salamanders than controls. Glutathione and related enzyme levels are reported. This work suggests that salamanders have levels of detoxification enzymes capable of the biotransformation of anthropogenic substances in soil rivaling that of mammals. Another investigation evaluated these same immunological parameters in white-footed mice (Peromyscus leucopus). This species was chosen based on the relative importance of small mammals to the community structure in many North American ecosystems. Mice were exposed to TNT in the feed at 0.264, 0.066, 0.033, and 0.017%, where actual daily dose estimates for males were 604, 275, 109, and 65; and for females was 544, 282, 143, and 70 mg/kg/d. An investigation to evaluate the specificity of commercially-available monoclonal antibodies specific to cell surface markers for thymocytes and splenocytes in inbred mice was unsuccessful. These results suggest the recognition epitopes of monoclonal antibodies prepared against Old-World mice are not conserved into Peromyscus, a New-World species. However, high dose males and females had larger spleens consistent with the hemolytic effects previously reported for mammals exposed to TNT. Further, males exposed at all levels had reduced phagocytic activity of splenocytes, and reduced hydrogen peroxide production associated with the two highest doses relative to controls. Females showed no response relative to treatment. This research has shown the feasibility for these types of investigations, and provides toxicity information valuable for modeling estimates of ecological risk. Further, the in situ exposures have provided media concentrations that are or are not toxic for species of concern. This type of information reduces the uncertainty associated with ingestion modeling estimates, dermal exposure estimates, and other factors not traditionally considered in toxicity studies. / Ph. D.
36

Generation of Heptagon-Containing Fullerene Structures by Computational Methods

Liu, Xiaoyang 14 December 2016 (has links)
Since the discovery three decades ago, fullerenes as well as metallofullerenes have been extensively investigated. However, almost all known fullerenes follow the classical definition, that is, classic fullerenes are comprised of only pentagons and hexagons. Nowadays, more and more evidence, from both theoretical and experimental studies, suggests that non-classical fullerenes, especially heptagon-containing fullerenes, are important as intermediates in fullerene formation mechanisms. To obtain fundamental understandings of fullerenes and their formation mechanisms, new systematic studies should be undertaken. Although necessary tools, such as isomer generating programs, have been developed for classical fullerenes, none of them are able to solve problems related to non-classical fullerenes. In this thesis, existing theories and algorithms of classical fullerenes are generalized to accommodate non-classical fullerenes. A new program based on these generalized principles is provided for generating non-classical isomers. Along with this program, other tools are also attached for accelerating future investigations of non-classical fullerenes. In addition, research to date is also reviewed. / Master of Science
37

Continuous crystallization of ultra-fine energetic particles by the Flash-Evaporation Process / Cristallisation continue des particules énergétiques ultra-fines par Évaporation-Flash

Risse, Benedikt 04 October 2012 (has links)
Sous l'effet d'une forte impulsion mécanique, d'une chaleur très forte ou d'une décharge électrostatique, un explosif comme le TNT ou le RDX peut accidentellement être initié. L'énergie apportée à l'explosif est convertie en chaleur, appelée point-chaud, dans des endroits spécifiques, contenant des impuretés, bulles de gaz, pores ouverts ou autres hétérogénéités. La taille d'un point-chaud de quelques micromètres peut être déjà suffisante pour initier une déflagration ou même une détonation. En réduisant la taille des particules de l'explosif, la formation des points-chauds est empêchée conduisant à un matériau moins sensible. Au sein de ce travail, un procédé continu est développé, fondé sur le principe de la cristallisation-flash, et permettant la préparation de particules énergétiques submicroniques en quantité de plusieurs grammes. Le procédé repose sur une opération de séchage par atomisation, au cours de laquelle une solution surchauffée est atomisée d'une manière continue. Afin de diminuer la taille moyenne des particules et d'obtenir une distribution de taille des particules très étroite, une étude paramétrique est réalisée. Au moyen de la cristallisation-flash, la préparation de composites énergétiques de haute qualité en grandes quantités est un succès. La qualité et quantité de ce composite énergétique sont uniques. Grâce au potentiel de ce procédé, la cristallisation-flash peut permettre la préparation de nombreuses substances et compositions énergétiques ou inertes / High explosives, such as TNT or RDX, may be accidentally initiated under the influence of a strong mechanical impulse, great heat or an electrostatic discharge. Smallest impurities, open pores, entrapped gases or other inhomogeneities within the explosive matrix may convert the delivered energy into heat, causing the formation of a so called hot-spot. A hot-spot size of a few micrometers can already be sufficient to initiate a deflagration or even a detonation of the explosive. By decreasing the particle size of the explosive, the formation of hot-spots is inhibited, resulting in a less sensitive material. In this work, a continuous operating flash-crystallization process was developed, being able to produce energetic submicron particles in a multigram scale. The process bases on a spray drying process where superheated solutions are continuously atomized. A parametric study was performed on this process in order to decrease the particle size and obtaining a narrower particle size distribution. By means of this flash-crystallization process, highly homogeneous energetic composites were prepared in a large scale. The quality and amount of the energetic composite are unique. The versatility of the flash-crystallization process allows the preparation of a large number of energetic and inert substances and compositions
38

Development of an Online Biosensor for the Detection of the Explosive TNT and the Illegal Drug Cocaine

Paul, Martin 14 March 2024 (has links)
Um Terroranschläge zu verhindern, werden schnelle, hochempfindliche Detektoren für Sprengstoffe benötigt. Neben Sprengstoffen ist auch der Drogenhandel ein großes gesellschaftliches Problem, welcher kriminelle Organisationen finanziert. Da bereits geringe Mengen an TNT oder Kokain einen Hinweis auf einen Anschlag oder auf Drogenschmuggel darstellen, muss der verwendete Detektor schnell aber dabei gleichzeitig sensitiv und selektiv sein. In dieser Arbeit wurde daher ein Biosensor zur Drogen und Sprengstoff Detektion, der auf auf einem Immunoassay basiert, entwickelt. Um die Performance sicherzustellen, wurden die genutzten Antikörper gründlich auf Eignung untersucht. Für die Affinitätssäule wurden monolithische Säulen hergestellt, welche eine hohe Oberfläche aufweisen. Zur Beschichtung der Säulen wurden Protein-Konjugate synthetisiert. Die Affinitätssäulen waren robust und zeigten eine sehr hohe Binde-Effizienz. Als Detektor wurde ein Fluoreszenz-Mikroskop aus kommerziellen Bauteilen konstruiert. Für den genutzten Fluoreszenzfarbstoff wurde eine Nachweisgrenze von 2 pM sowie ein dynamischer Bereich bis 1000 pM erreicht. Für die Fluidik wurden eine Spritzenpumpe sowie mikrofluidische Bauteile genutzt, welche eine Detektionszeit von 1.5 Minuten ermöglichten. Für TNT wurde mit dem Biosensor eine Nachweisgrenze von 130 pM erzielt. Der Biosensor zeigte außerdem keine Kreuzreaktivität mit gängigen Sprengstoffen. Für Kokain wurde eine Nachweisgrenze von 15 pM im Biosensor erreicht. Zusätzlich wurde für Kokain ein Wischtest entwickelt, welcher in drei Minuten Kokainmengen von 300 pg detektieren kann. Der entwickelte Biosensor gehört zu den besten Sensoren zur TNT- und Kokaindetektion und zeigt eine vergleichbare oder bessere Performance als Flüssigchromatographie mit Massenspektrometrie-Kopplung. Die Flexibilität beim Analyten sowie der Verzicht auf Lösungsmittel machen diesen Biosensor zu einem interessanten Kandidaten für hochempfindliche Messsysteme. / The fast detection of explosives is essential to prevent terror attacks. Besides explosives, the trafficking of illegal drugs is a major problem, which must be addressed to reduce criminal organizations’ revenue streams. As low amounts of these substances may indicate trafficking or a bomb threat, sensitive, selective and fast detection methods are required. Therefore, a biosensor was developed in this work, which relies on an immunoassay. To ensure sensitive and selective performance the used antibodies were characterized in depth. To obtain affinity columns, glass columns were manufactured and used. As column coating affinity conjugates were synthesized. The affinity columns showed efficient antibody trapping and were long-term stable. As a detector an epi-fluorescence microscope was built to monitor the sample. The sensor features consumer-grade parts rendering it easily accessible. For the used fluorophore a limit of detection (LOD) of 2 ppt with a linear range up to 1000 pM was achieved. Due to the use of a syringe pump and an injection valve a continuous fluidic for the biosensor was obtained. The used microfluidic parts resulted in detection times of only 1.5 min. For TNT a LOD of 130 pM was achieved. Additionally, the biosensor showed no cross-reactivity with common high explosives. For cocaine a LOD of 15 pM in solution was achieved and a surface wipe sampling method was demonstrated, which was able to detect 300 pg cocaine on surfaces within three minutes reliably. This biosensor belongs to the fastest and most sensitive cocaine and TNT detectors with sensitivity on par or better than liquid chromatography coupled with mass spectroscopy. Furthermore, the biosensor is affordable, very modular analyte-wise and requires no solvents or microplastic carriers. Therefore, it is a fascinating approach for future high-sensitivity monitoring applications.
39

Kinetics of 2, 4, 6-Trinitrotoluene Reduction by Pseudomonas Putida

Sheikh, Kharisha S. 13 October 2006 (has links)
No description available.
40

Developmental and Functional Roles of Troponin-T Isoforms, and Exploring Genome-Wide Alterations in Drosophila Indirect Flight Muscle Mutants

Madan, Aditi January 2015 (has links) (PDF)
Muscle contraction is a highly fine-tuned process that requires the precise and timely construction of large protein sub-assemblies to form sarcomeres, the individual contractile units. Mutations in many of the genes encoding constituent proteins of this macromolecular machine result in defective functioning of the muscle tissue, and in humans, often lead to myopathic conditions like cardiomyopathies and muscular dystrophies, which affect a considerable number of people the world over. As more information regarding causative mutations becomes available, it becomes imperative to explore mechanisms of muscle development, maintenance and pathology. In striated muscles, contraction is regulated by the thin filament-specific tropomyosin (Tm) – troponin (Tn) complex (Ca2+-binding troponin-C, inhibitory troponin-I and tropomyosin-binding troponin-T). These troponin subunits are present in 1:1:1 ratio on thin filaments, with 1 Tm-Tn complex present on every 7th actin molecule. This stoichiometry is tightly regulated, and disturbances have been associated with functional defects. Each of these proteins has multiple isoforms, whose expression is controlled both spatially and temporally. The expression of specific combination of isoforms confers specific contractile properties to each muscle subtype. Drosophila melanogaster has been a preferred model of choice to study various aspects of muscle development for decades. In this study, the Indirect Flight Muscles (IFMs) of Drosophila have been used to investigate developmental and functional roles of two temporally regulated isoforms of a vital structural and regulatory component of the sarcomere – Troponin T (TnT). On a larger scale, whole genome expression profiles of mutants that are null for major myofbrillar proteins have also been discussed. IFMs serve as an excellent model system to address these questions, owing to the extreme ease of genetic manipulability in this system, and high degree of homology between mammalian and Dipteran cytoskeletal proteins. Chapter 1 covers basics of muscle biology, and the role of TnT in muscle contraction. Phenomena responsible for generating diversity in genes encoding muscle proteins – alternative splicing and isoform switching – have also been discussed. These mechanisms are highly conserved, as are patterns of TnT splicing and isoform expression across phyla. Mutations leading to altered splicing patterns lead to myopathic conditions, and the importance of model systems to study muscle biology has been emphasized. The advantages of studying Drosophila IFMs and a comprehensive overview of IFM development has been covered. The resources and experimental tools used have been described in Chapter 2. Two isoforms of TnT are alternatively spliced in the Drosophila thorax – one containing alternative exon 10a (expressed in adult IFMs and jump muscle); and one containing alternative exon 10b (expressed in pupae and newly eclosed flies). These exons are spliced in a mutually exclusive manner, and defects in splicing have been reported to cause uncontrolled, auto-destructive contractions. In Chapter 3, a splice mutant of TnT, up1, has been discussed, with respect to its developmental profile. Transgenic rescue experiments with two separate isoforms demonstrate rescue at the structural as well as functional level. Transgenic over-expression, however, leads to functional abnormalities, highlighting the importance of stoichiometry in multi-protein complexes. In Chapter 4, molecular signals that bring about the developmentally regulated TnT isoform switch are discussed. A splicing factor, Muscleblind, has been transgenically knocked down in normal and mutant IFMs to study effects on muscle function. Chapter 5 looks at whole genome transcriptional alterations in muscles null for either actin or myosin. All significant expression changes have been classified into categories based on different biological processes, and an attempt to differentiate generic muscle responses from filament-specific responses has been made. In conclusion, the studies have highlighted the importance of TnT isoform switching, and that extended expression of a pupal stage-specific isoform can partially compensate for loss of the adult isoform. Also, in the absence of major myofibrillar proteins, stress response pathways like heat shock response and protein degradation pathways are activated, along with a subset of metabolic responses that are unique to the thin or thick filament systems.

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