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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.
1

Role of macromolecules in coccolithophore biomineralization

Walker, Jessica Mary January 2018 (has links)
Biomineralization refers to the production of mineralized tissues by organisms. The fine control which organisms can exert over this process produces crystals with morphologies and properties contrasting to that of non-biogenic crystals and specifically altered to suit the required functional need. A key model system of biomineralization are a unicellular marine algae, coccolithophores, which produce calcium carbonate scales known as coccoliths. These coccoliths are comprised of arrangements of single crystals of calcite interlocked to form a plate-shaped structure. Coccoliths are developed intracellularly in a specialised compartment called the coccolith vesicle, before being extruded to the cell surface. In this work, two vital components of the coccolith biomineralization process are investigated - a soluble polysaccharide thought to act as a habit modifier and an insoluble organic scaffold known as a baseplate that provides the surface for nucleation and growth of the crystals. Whilst both these elements are thought to play a key part in the biomineralization process, the role of each is not fully understood. To investigate the effect of coccolith-associated polysaccharides (CAPs) on nucleation and polymorph selection, two systems that promote different polymorphs of calcium carbonate were utilised. In both systems, the intracrystalline polysaccharide fraction extracted from one species, Gephyrocapsa oceanica, was able to promote calcite nucleation in vitro, even under conditions favouring the kinetically-privileged polymorphs of calcium carbonate: vaterite and aragonite. As this property is not observed with CAPs extracted from its 'sister species', Emiliania huxleyi, the in vivo function of CAPs may differ between the two species. Both cryo-transmission electron microscopy (cryoTEM) and scanning electron microscopy (SEM) were used to determine the mechanism of calcite growth in the presence of G. oceanica CAPs, showing its impact on the forming amorphous calcium carbonate (ACC), decreasing the size of the particles and producing irregular, angular particles. Using cryo-electron tomography (cryoET), it was possible to create a 3D representation of the structure of the baseplate from the coccolithophore Pleurochrysis carterae, revealing its two-sided organisation. Examination of several stages of the coccolith growth process demonstrated the interlocking nature of the calcite crystals that make up the coccolith and the progression of the crystal morphologies over time, and the interaction of these crystals with the baseplate rim. Additionally, the effect of inhibiting carbonic anhydrase (CA), an enzyme involved in the regulation of carbonate species, revealed that inhibition of CA can affect coccolithogenesis as well as cell proliferation.
2

Elucidating the Role of gpW: an Essential Baseplate Protein in Bacteriophage P2

Fatehi Hassanabad, Mostafa 27 November 2013 (has links)
The long, contractile tails of myophages are the conduit for phage DNA transfer into the bacterial host cell and the most important part of the myophage tail is the baseplate; a complex structure, distal to the phage head. To better understand the structure and function of myophage baseplates, a component of the phage P2 baseplate, gpW was studied. This protein is widely conserved among myophages and is essential for the formation of infectious phage particles. Bioinformatic work confirmed that gpW homologues are found in almost all myophages and in many prophages. Moreover, gpW was shown to be a structural component of the virion; and, using electron microscopy, it was found to be at the top of the P2 baseplate. It was also found that some single residue substitutions can completely disrupt gpW function. Finally, evidence is presented that at least eight different proteins may be required to form intermediate P2 baseplate structures while other proteins may be necessary for the formation of stable baseplate complexes.
3

Elucidating the Role of gpW: an Essential Baseplate Protein in Bacteriophage P2

Fatehi Hassanabad, Mostafa 27 November 2013 (has links)
The long, contractile tails of myophages are the conduit for phage DNA transfer into the bacterial host cell and the most important part of the myophage tail is the baseplate; a complex structure, distal to the phage head. To better understand the structure and function of myophage baseplates, a component of the phage P2 baseplate, gpW was studied. This protein is widely conserved among myophages and is essential for the formation of infectious phage particles. Bioinformatic work confirmed that gpW homologues are found in almost all myophages and in many prophages. Moreover, gpW was shown to be a structural component of the virion; and, using electron microscopy, it was found to be at the top of the P2 baseplate. It was also found that some single residue substitutions can completely disrupt gpW function. Finally, evidence is presented that at least eight different proteins may be required to form intermediate P2 baseplate structures while other proteins may be necessary for the formation of stable baseplate complexes.
4

Caractérisation moléculaire du systeme de secrétion de type VI d'escherichia coli enteroagrégatif et de ses mécanismes de régulation . / Structure and function of the type vi secretion system tail

Brunet, Yannick 09 July 2013 (has links)
Résumé : La compréhension des contraintes qui régissent l'assemblage des machineries supramoléculaires – qu'elles soient solubles ou bien ancrées dans les membranes biologiques – est un enjeu scientifique majeur.Le système de de sécrétion type VI (T6SS) est un organelle bactérien récemment mis en évidence qui a pour particularité de posséder une origine évolutive commune avec le bactériophage T4. En raison de cette origine évolutive commune, certaines sous unités du T6SS et du bactériophage T4 présentent des structures comparables. Cependant, un grand nombre des sous unités du T6SS reste à caractériser. Parmi celles-ci, les protéines SciB et SciC sont retrouvées dans tous les systèmes de sécrétion de type VI suggérant que ces deux protéines participent à la formation du "core-complexe": le complexe minimal requis pour le fonctionnement du T6SS. / The recently identified type VI secretion system has been demonstrated to be involved in most of these processes. The T6SS is a highly complex macromolecular machine that allows Gram-negative bacteria to deliver effector proteins to both prokaryotic and eukaryotic cells in a contact-dependent manner. The T6SS promotes therefore antibacterial competition, virulence towards eukaryotes or even both. The T6SS is composed of a minimal set of 13 subunits, which are currently believed to form the core apparatus. They assemble two distinct sub-complexes: one is a cytosolic contractile structure related to the tail of contractile bacteriophages, whereas the other spans the whole cell envelope. Therefore, the T6SS is generally depicted as an inverted phage tail anchored to the cell envelope through its membrane-associated complex. Contractile tails are currently thought to assemble from four structural elements: the baseplate, the internal tube, the contractile sheath and the tail terminator. The aim of my Ph.D. work was to further characterize the assembly and function of the T6SS phage tail-like complex in enteroaggregative E. coli. In this thesis document, I provide evidence that the internal tube assembles from Hcp hexamers stacked in a head-to-tail manner and that this internal cylinder is used as a template during sheath assembly. I also characterized a sub-complex of three proteins (TssEFG) that forms the baseplate of the T6SS and controls the polymerization of the tube and sheath. Finally, I recently showed that the T6SS functions like a nano-crossbow to kill target cells as the contraction of the T6SS results in prey cell death during interbacterial competition.
5

Caractérisation structurale de la partie trans-périplasmique et de la plaque de base du système de sécrétion de type VI de EAEC 042 sci1 / Structural characterisation of trans-periplasm and baseplate components from the EAEC 042 sci1 type VI secretion system

Nguyen, Van-Son 05 December 2016 (has links)
Chez les procaryotes, les protéines sont synthétisées dans le cytoplasme avant d'être transportés vers différentes destinations, intra- ou extra-cellulaires. Les bactéries Gram-négatives ont mis au point une grande collection de mécanismes et systèmes, appelés systèmes de sécrétion bactérienne, pour sécréter des protéines à travers leur paroi cellulaire vers l'extérieur. Le système de sécrétion de type VI, identifié dans les années 2006-2008, est une nano-machine polyvalente répandue chez les bactéries pathogènes. Il y a de nombreuses preuves que T6SS injecte des protéines toxiques (effecteurs) directement dans les cellules eucaryotes et procaryotes pour les tuer. Pour empêcher la destruction cellules provenant de la même espèce, les bactéries possédant un T6SS produisent également des protéines d'immunité qui neutralisent les effets toxiques des effecteurs de leurs congénères. Le T6SS est formé de 13 composants de coeur (nommés TssA-M) en une structure souvent comparée à un "bactériophage inversé". La queue, semblable à celle de phages, a une forme tubulaire (la gaine et le tube interne) et polymérise à partir d'une plaque basale ancrée sur un complexe membranaire trans-périplasmique. La contraction de la gaine fournit l'énergie nécessaire pour propulser le tube intérieur à travers la paroi vers les cellules proies. Dans le cadre de ma thèse, je me suis impliqué dans la détermination de la structure et la dynamique de certains composants du T6SS de la d’Escerichia coli enteroaggrégatif (EAEC). Plusieurs structures ont été déterminées et analysées. Quatre articles ont été publiés et deux autres sont en préparation. / In prokaryotes, proteins are synthesized in the cytoplasm before being transported to various destinations, intra- or extra-cellular. Gram-negative bacteria have developed a large collection of mechanisms and systems, termed bacterial secretion systems, to secrete proteins through their cell wall to the exterior. The type VI secretion system, identified in years 2006-2008, is a versatile nano-machine prevalent in pathogenic bacteria. There have been many evidences that T6SS delivers toxic proteins directly into both eukaryotic and prokaryotic cells to kill them. To prevent killing of sibling cells (cells from the same species), T6SS+ cells produce also immunity proteins that neutralize the toxic effects of their cognate effectors. T6SS contains 13 core-components (TssA-M), assembling a structure often quoted as an “inverted bacteriophage”. A phage-like tubular tail (the sheath and the internal tube) polymerizes from a baseplate-like complex, anchored to the cell internal and outer membranes via a membrane anchored complex spanning the periplasm. Contraction of the sheath provides the necessary energy to propel the internal tube through the wall towards the prey cells. In the framework of my PhD, I became involved in determining the structure and dynamics of some components of the EAEC sci1 T6SS, mostly on the membrane and baseplate subcomplexes. Several structures have been determined and analysed. Four articles have been published and two other are in preparation.
6

Medicínské centrum / Medical center

Vokřál, David January 2014 (has links)
This thesis deals with the detailed documentation of the medical center . Estimated location of this building is on land No. 677/1 in Kutna Hora in the hospital Kutna Hora in the administrative area of Kutna Hora in Central Bohemia. Currently no land use. The land is owned by the investor , which is the Central Region. Newly built four-storey medical center will serve mainly for the provision of outpatient health care professional doctors and pharmacy , then there will be placed exit station emergency medical services and emergency medical call center services 155, 112 and emergency office space. The project was based on the layout of the study. The result of this work is to complete detailed documentation of the A building. Documentation includes drawings situation , surveying the situation , floor plans , sections, elevations , drawings, foundations , ceilings and details. Furthermore, a technical report , listing the elements of fire safety of the building , Thermal and acoustic assessment of the construction , specializing processed from concrete structures and building ventilation .
7

Nosná železobetonová konstrukce / Load-bearing reinforced concrete construction

Klajba, Daniel January 2015 (has links)
The aim of diploma thesis is to design monolithic reinforced concrete underground structure, which is partly under existing building and partly will form the basis of a new outbuilding. Structure is designed as white tub, whitout any additional isolations against water a ground humidity. All structure elements (slabs, walls, beams) was designed according to standard ČSN EN 1992-1-1 for ultimate and serviceability limit state. Structural analysis was performed using Scia Engineer 2013 – Student version. The results were validated by simplyfied manual method.
8

Temperatursprickskatalogen : Hjälpmedel vid beräkning av temperatursprickor i vanligt förekommande  betongkonstruktioner. / Thermal crack catalogue : Assistance when calculating thermal cracks in common concrete structures.

Swärd, Sofia, Hallberg, Markus January 2012 (has links)
Rapporten innehåller inledningsvis en faktadel med allmän information kring temperatursprickor i betong. Här presenteras bl a uppkomsten av fenomenet, vilka typer av sprickor som förekommer och vad ett tvång är. Tanken är att ge läsaren tillräcklig kunskap för att kunna förstå sig på de övriga delarna i rapporten. Resultatet och det huvudsakliga arbetet redovisas i form av tabeller med tillhörande illustrationer där det går att utläsa vilken sprickrisk som förekommer vid flera specifika fall och vilken åtgärd som bör vidtas för att eliminera sprickrisken. Som konstruktör kan du med din egen indata, dvs. dimensioner och temperaturer, följa tabellen och finna resultatet för ditt specifika fall. De konstruktionstyper som presenteras är bottenplatta, stödmur och plattrambro. En tillhörande databas i elektronisk form finns tillgänglig som en bilaga där varje beräknat fall är sparat. Filerna är enkla att modifiera för att göra det möjligt att genomföra ytterliggare beräkningar i de fall tabellerna är otillräckliga. Rapporten innehåller även ett avsnitt med förutsättningar till tabellerna där det går att utläsa arbetsgången och vilka parametrar som har använts. / The initial part of the report contains general information about thermal cracks. This section describes the origin to the cracks, what type of cracks that occurs and the force causing the problem. The major reason with this chapter is to give the reader enough knowledge to understand the rest of the report. The result and the main work are presented in tables with belonging illustrations. Each table contains the risk of cracking that occurs in several specific concrete structures and how to eliminate the risk. The report covers the following three types of structures: baseplate, retaining wall and integral bridge. The constructor can with his/her own dimensions and temperatures simply use the table to find the risk of cracking. A database including all the calculated files for each specific case is attached to the report. The files can easily be modified by the user in case the information in the tables is insufficient. All the precise circumstances and priority in the project are presented in the chapter “Förutsättningar och arbetsgång”.
9

Horský penzion s restaurací / Mountain guesthouse with a restaurant

Stloukal, Ondřej January 2014 (has links)
The project is handled by complete documentation , brand new detached house with mountain restaurants at the level of documentation for construction . The building is designed in the village Olšany district. Šumperk on plot No. 261/1 , 261/5 , 261/9 and 261 of / 12. Built up area is 1465 square meters , of which the construction of the house itself has a 445.2 square meters . The basement and ground floor is used for restaurants, restaurant facilities and staff , reception and social facilities for guests . The second floor and the attic is designed to accommodate guests. The pension has a capacity of 20 people , of which there are six double rooms and two suites on the top floor , each for four people. The operation of the pension are a total of four employees. The restaurant , with a capacity of 102 people , the total number of employees 8 . The building is designed as two rectangles perpendicular to each other forming the letter T. The building is based on the footings of plain concrete foundation slab drag over the basics with reinforcing karisítí . Walling system from Heluz , partitions from the system Knauf, reinforced concrete ceilings . Outdoor perimeter walls is insulated with polystyrene foam . The roof is gabled and three graduated height of the ridge , where the highest elevation is the main part +11.370 m , roof pitch of 35 °. The building is connected to the local road and the available utilities. Proposal for hotel and restaurant is processed in accordance with applicable standards and regulations for the country.
10

Wellness centrum ve Slavkově u Brna / Wellness centre in Slavkov u Brna

Kovář, Stanislav January 2015 (has links)
Master´s thesis ,,WELLNESS centre in Slavkov u Brna" is processed in the from of project documentation. The building is a partially basement, it has three floors and an attic, roofed in sellar rooftop and partially counter rooftop. The house is designed to plot No. 1787/1, 1787/30 in Slavkov u Brna Slovanská street. Built up area is 554,7 square meters. The basement, ground floor and second floor belongs to a wellness and a guesthouse. The third floor is used for housing owners. The building is based on the footings of plain concrete foundation slab drag over the basics with reinforcing karisítí . Walling system and ceilings from Porotherm , partitions from the system Knauf. The building is connected to the local road and the available utilities.

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