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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.
481

Studium přípravků do odlučovačů tuků / Study of preparations for fat separators

Gojkovic, Živan January 2009 (has links)
Diploma thesis was concentrated at testing of a single commercial product designed as a lipid residue removal agent, applicable in grease trap vessel. Concept was, that product is to be tested for possible content of viable microbial culture with ability to utilize various kinds of vegetable oils and animal fats, by producing functional lipase. Four types of vegetable oils were used, and two fats of animal origin: olive oil, palm oil, rapeseed oil, sunflower oil, lard and beef fat. Determined fat characteristics were: point of the saponification, the acid value, the ester value and the peroxide value. Submerged cultivation was performed on specially composed medium in which the oil or fat of choice, was mixed later. Lipolytic activity and biomass growth measurement was performed using spectrophotometry, lipid degradation ability was measured using titrimetry. Based on results it can be stated that tested microorganisms, originated from product, and its lipase has ability to successfully utilize all of used fats and oils and thus, theoretically, remove its content from grease trap.
482

Odbourávání tuků v odpadech / Degradation of fats in wastes

Artýszková, Jana January 2011 (has links)
Submitted master’s thesis is focused on the study of possibilities of lipids degradation in particular wastewaters originating in food industry or restaurants. The effort is given to the employment of lipolytic activity presenting microorganisms. In the literature review, wastewater treatment with aim on the sludge management and fat separators are described, as a way how to pre-treat these wastewaters. In this part the enzymes lipases of microbial origin are researched from point of view of their production conditions and possible applications. The experimental part is dedicated to the research of optimization of cultivation conditions for lipases production employing selected microorganisms (Bacillus subtilis, Geobacillus thermodenitrificans, G. thermocatenulatus and mixed bacterial culture Thermus and Bacillus) and a commercial formulation (Sany Duo Spezial). Lipases production and growth of microorganisms are determined spectrofotometrically on various concentrations of lipids. Moreover, employing the solid nutrition medium, the effect of detergents onto the Bacillus subtilis culture was assessed, since detergents are generally abundant in this particular wastewaters. As a conclusion, vide supra mentioned microorganisms were characterized according to their abilities to degrade triacylglycerols.
483

Study of high temperature and high density plasmoids in axially symmetrical magnetic fields

Berger, T., Konheiser, J., Anikeev, A. V., Prikhodko, V. V., Bagryansky, P. A., Kolesnikov, E. Yu., Soldatkina, E. I., Tsidulko, Yu. A., Noack, K., Lizunov, A. A. January 2009 (has links)
Within the framework of an Institutional Partnership of the Alexander von Humboldt Foundation, the Budker Institute of Nuclear Physics Novisibirsk (BINP) and Forschungszentrum Dresden-Rossendorf worked together in a joint project devoted to the research at the coupled GDT-SHIP facility of the BINP with the focus on the study of plasma phenomena within the SHIP mirror section. The project began at July 1st, 2005 and ended on August 30th, 2008. It included work packages of significant theoretical, computational and analyzing investigations. The focus of this final report is on the presentation of results achieved whereas the work that was done is described briefly only. Chapter 2 illustrates the GDT-SHIP facility and describes shortly the planned topics of the SHIP plasma research. Chapter 3 explains the main extensions and modifications of the Integrated Transport Code System (ITCS) which were necessary for the calculations of the fast ion and neutral gas particle fields in SHIP, describes briefly the scheme of computations and presents significant results of pre-calculations from which conclusions were drawn regarding the experimental program of SHIP. In chapter 4, the theoretical and computational investigations of self-organizing processes in two-component plasmas of the GDT-SHIP device are explained and the results hitherto achieved are presented. In chapter 5, significant results of several experiments with moderate and with enhanced plasma parameters are presented and compared with computational results obtained with the ITCS. Preparing neutron measurements which are planned for neutron producing experiments with deuterium injection, Monte Carlo neutron transport calculations with the MCNP code were also carried out. The results are presented. Finally, from the results obtained within the joint research project important conclusions are drawn in chapter 6.
484

A Cryogenic Mass Spectrometer for Action Spectroscopy of Single Nanoparticles

Esser, Tim Kaspar David 16 April 2019 (has links)
Diese Dissertation legt den Grundstein für eine neue experimentelle Technik zur Untersuchung einzelner Nanopartikel in der Gasphase, durch Kombination von Nanopartikel-Massenspektrometrie (NPMS) mit Photodissoziations-Wirkungsspektroskopie. Zu diesem Zweck wurde ein neues NPMS Experiment entworfen, konstruiert und charakterisiert. NPMS, ist eine Technik bei der die absolute Masse eines einzelnen Nanopartikels in einer Paul-Falle optisch und daher zerstörungsfrei bestimmt wird. Die wesentliche Neuerung des aktuellen Aufbaus, und Kernelement dieser Arbeit, ist eine neue Tieftemperatur-Ionenfalle, mit verbessertem optischen Zugang, Temperaturkontrolle (8 to 350 K) und elektrischem Potential im Vergleich zu bisher verwendeten Modellen. / This doctoral thesis lays the foundations for a novel experimental technique, combining nanoparticle mass spectrometry (NPMS) with photodissociation action spectroscopy, to investigate single nanoparticles in the gas phase. To this end, a new NPMS setup was designed, constructed and characterized. NPMS , currently used in only a few laboratories worldwide, is a technique where the absolute mass of a single nanoparticle, trapped in a quadrupole ion trap (QIT), is determined non-destructive by optical means. The essential novelty of the current setup, and core element of this thesis, is a new cryogenic split-ring electrode trap (SRET) design, with improved optical access, temperature control (8 to 350 K) and trapping potential compared to previously used versions.
485

Varying the Aspect Ratio of Toroidal Ion Traps: Implications for Design, Performance, and Miniaturization

Hettikankanange, Praneeth Madushan 07 December 2020 (has links)
A large aspect ratio leads to higher ion capacity in miniaturized ion trap mass spectrometers. The aspect ratio (AR) of an ion trap represents the ratio between an extended trapping dimension and the characteristic trapping dimension. In contrast to linear and rectilinear traps, changing the AR of a toroidal ion trap (TorIT) results in changes to the degree of curvature and shape of the trapping potential, and hence, on performance as a mass analyzer. SIMION simulations show that higher-order terms in the trapping potential vary strongly for small and moderate AR values (below ~10), with the effects asymptotically flattening for larger AR values. Because of the asymmetry in electrode geometry, the trapping center does not coincide with the geometric center of the trap, and this displacement also varies with AR. For instance, in the asymmetric TorIT, the saddle point in the trapping potential and the geometric trap center differ from +0.6 to -0.4 mm depending on AR. Ion secular frequencies also change with the AR. Whereas ions in the simplified TorIT have stable trajectories for any value of AR, ions in the asymmetric TorIT become unstable at large AR values. Variations in high-order terms, the trapping center, and secular frequencies with AR are a unique feature of toroidal traps, and require significant changes in trap design and operation as the aspect ratio is changed.
486

Předlužení mladé generace v ČR / Over-indebtedness of young people in the Czech Republic

Lišková, Veronika January 2016 (has links)
The master's thesis "Over-indebtedness of Young Generation in the Czech Republic" deals with over-indebtedness of individuals at the age of 18 to 26 years. Over-indebtedness is a general social problem as all age groups get overburdened with debt. However, it is important to focus on the issue of young people's over-indebtedness directly because the young generation represents people who are or will be active in the general working process. The authoress of the thesis points out the young generation's over-indebtedness and provides an overview of development of this issue in 2008 - 2015. She also examines the most frequent causes which she has found out using questionnaires and data collected. In her work, the authoress also outlines a gradual development of possible indebtedness, which primarily includes loans, from both banks and other institutions, followed by a court procedure and execution of the judgement. A possible solution to over-indebtedness then consists in filing a petition with a court to permit a personal discharge from debts. The work aims at finding out and examining development of the young generation's indebtedness in the Czech Republic, analysing causes of over-indebtedness, describing the changes of the causes in time and at analysing the process of discharge from debts, which...
487

Postfledging Survival and Habitat Use of Spotted Towhees (Pipilo maculatus) in an Urban Park

Shipley, Amy Ann 01 January 2011 (has links)
Habitat fragmentation, and the resulting increase in edge habitat, has important effects on birds, including the increased probability of nest predation, changes in habitat structure, and the increased presence of non-native plant species. It is critical to understand the effects of fragmentation at all stages of the avian life cycle, including the often overlooked postfledging period. Because much of juvenile mortality occurs during the immediate postfledging period, and juvenile mortality contributes substantially to population dynamics, it is necessary to understand if fledgling survival is reduced in edge habitats and if fledglings' survival is influenced by their habitat use. During 2008 and 2009 I radio-tracked 52 fledgling Spotted Towhees (Pipilo maculatus) during the 30-day postfledging period in a 24-ha urban park near Portland, Oregon. Thirty-six fledglings (69%) survived the 27-day tracking period (an estimated 62.1% survived the entire 30-day postfledging period). At least 9 of 16 predation events were attributable to domestic cats (Felis domesticus) or Western Screech-owls (Megascops kennicottii). Although fledglings were more likely to be found near edges than the park interior, fledglings located closer to park edges had a higher probability of dying. However, I found that towhee nests were more likely to be found near edges, nests near edges produced more fledglings, and nestlings near edges were heavier. I used a STELLA-based stochastic model of nest success and fledgling survival to show that the benefits initially gained by nesting near edges were reversed during the postfledging period. The number of fledglings per nest that survived to the end of the 30-day postfledging period was significantly lower near edges than in the park interior. This apparent preference for nesting near edges, paired with higher fledgling mortality near edges, is consistent with the idea that edges are ecological traps. Fledgling habitat was significantly more structurally dense and had a greater abundance of non-native plant species, particularly Himalayan Blackberry (Rubus armeniacus), than nest habitat. Towhees avoided English Ivy (Hedera helix) for both nesting and care of fledglings. However, fledgling survival was not related to vegetation characteristics, which suggests that increased fledgling mortality near edges was a direct result of increased predator abundance or predation near edges, and was not an artifact of changes in habitat near edges. My results help to establish that fledgling survival and the unique habitat requirements of fledglings should be considered along with nest success and nest habitat when examining the effects of habitat fragmentation on bird populations. More broadly, this study has important implications for conservation, as it exemplifies how phenomena such as ecological traps created by anthropogenic changes in the environment can be overlooked if only one life history stage is studied.
488

Udržování integrity chromosomů na modelu Giardia Intestinalis. / Maintenance of chromosomes integrity in Giardia intestinails as a model organism.

Uzlíková, Magdalena January 2019 (has links)
Giardia intestinalis is a protozoan causing diarrhea worldwide. Beside its medical importance, it is evolutionary distant protist with two nuclei within a cell adapted for parasitic life in the environment poor of oxygen. Its genome is small and compact in term of gene content and size. It is therefore an attractive model organism for studies of minimal requirements for cellular processes. Present work brings new partial information on different levels of chromosome integrity maintenance of this parasite. Our study presents characteristics of chromosome termini and their protection. We localized telomeres during all stages of the trophozoite cell cycle and determined the length of Giardia telomeres ranging from 0.5 to 2.5 kb, we proved an existence of an active telomerase enzyme synthesizing telomeric repeats in in this parasite, despite the fact that giardial telomerase is structurally divergent. Present data support the view that the chromosomal termini in Giardia are maintained in a conservative manner that is common to other eukaryotes. We described effects of commonly used drug for treatment of anaerobic infections, metronidazole, on DNA and cell cycle progression in susceptible and resistant cell lines. Incubation of cells with this drug causes phosphorylation of histone H2A in cell nuclei...
489

The Effects of Habitat Management on Wildlife Use in a Managed Loblolly Pine Forest

McCollum, Johannah Reed 10 August 2018 (has links)
To improve habitat quality for wildlife, habitat managers prescribe various disturbances. Habitat management techniques alter the vegetation structure, composition, and quality, changing food and cover resources and availability. To investigate how habitat management and vegetation heterogeneity affect space use by wildlife species, I deployed 81 camera-traps and collected fine scale vegetation data across a variety of treatments (i.e., canopy reduction, prescribed fire, and herbicide application) in a managed loblolly pine forest. I created a new method for accounting for imperfect detection and error in camera count data. My method provided better inference about the effects of variables on animal use. Species responded differently to different functional groups of plants, but predicted use from generalized additive models showed higher use in the most intensively managed pine stands, indicating that management promotes animal use by improving habitat quality. Animals used every treatment, indicating the need for heterogeneity in resources when managing wildlife.
490

Development of a Strontium-87 Ion Interferometer

Erickson, Christopher Joseph 14 December 2011 (has links) (PDF)
I present the construction of a low-velocity intense source (LVIS) of laser-cooled neutral strontium using permanent ring magnets. The LVIS consists of a magneto-optical trap from which cold strontium is extracted in a well-collimated beam. I also present the development and implementation of a full suite of low-noise, high-bandwidth laser control electronics including a microcontroller unit. This microcontroller remotely controls and monitors the current driver, temperature controller, and PID lock circuit for each diode laser simultaneously. The current driver output is accurate to within 2 micro-amps and repeatable to with a few nano-amps. The noise spectral density of the current driver hits a floor of 10^(-10) amps per root Hz at ~50 Hz and has a modulation bandwidth of ~50 MHz. The PID lock-circuit includes a scan-balancing option that we have used to scan an AR coated laser diode ~30 GHz mode-hop free. I describe the construction of an 80 mW frequency doubled 461 nm laser system using PPKTP for cooling and trapping neutral strontium in the LVIS. The LVIS, the electronics systems, and the 461 nm laser system represent major milestones on the way to producing a matter-wave interferometer using Sr-87 ions. The interferometer is based on an optical Raman transition between the hyperfine ground states of the Sr-87 ion. The ions will be produced by exciting the strontium LVIS beam to an auto-ionizing state in the continuum. In the interferometer two half-pi pulses of light and one pi pulse will be delivered to the ions to split and recombine their wave functions. I present calculations of the predicted sensitivity and a discussion of the possible applications. I present a method for locking a 407.8 nm laser to the 5s doublet S J=1/2 to 5p doublet P J=3/2 strontium ion transition in a neutral vapor. I present calculations for the necessary vacuum levels for the experiment and describe the preparation and assembly of the vacuum apparatus. The major vacuum system consists of two connected elastomer sealed chambers: one at 10^(-7) Torr and the other at 10^(-10) Torr separated by a region of low conductance. I present a Sr vapor cell constructed from standard CF fittings that allows the strontium to be heated to ~730 C, which can also be run as a thermal beam. I present a method for protecting the viewports on small-form alkali-earth vapor cells using lead or indium foil during the evaporation of oxide layers. Finally, I report on the current status of the experiment as well as detail future work on the apparatus.

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