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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

Lokala skillnader i lufttemperatur på ön Mefjärd / Local Air Temperature Differences on the Island Mefjärd

Sellergren, Martin January 2016 (has links)
Hur mycket lufttemperaturen varierar på en plats på land beror till stor del av platsens avstånd till havet. Ju längre ifrån havet platsen ligger, ju mindre influeras dess lufttemperatur av havstemperaturen. Hav värms och kyls långsammare än land vilket innebär att maritima platser har en stabilare lufttemperatur i jämförelse med inlandet.             Syftet med denna studie är att undersöka lufttemperaturer på en liten ö för att bestämma i vilken grad havsavståndet påverkar temperaturvariationer på liten skala. Mätningarna skedde på ön Mefjärd i Stockholms skärgård. Mefjärd har en storlek på ca 3000 x 400 m och är belägen drygt 10 km från Sveriges östkust. Mätningar av lufttemperatur gjordes kontinuerligt mellan den 20/3 och 22/4 både vid strandlinjen och vid mitten av ön. Även havstemperatur, vind och solinstrålning mättes. Statistiska beräkningar genomfördes och grafer över temperaturer och resterande uppmätt data skapades. Resultaten visade bland annat att lufttemperaturen vid strandlinjen var stabilare och generellt sätt närmare havstemperaturen än vad lufttemperaturen mitt på ön var samt att lufttemperaturen mitt på ön var känsligare för skillnader i solinstrålning än lufttemperaturen vid strandlinjen. Dessa resultat var tydliga trots att studien utfördes på liten skala. / The amount of air temperature variation at some location on land depends to a large extent on the distance between the location and the sea. The further from the sea a place is located, the less is its air temperature influenced by the sea temperature. The sea is heated and cooled more slowly than land which means that maritime locations has a more stable air temperature compared to inland locations.             The purpose of this study is to examine air temperatures on a small island in order to determine to what extent air temperature variations are influences by distance to sea, on a small scale. Measurements were taken on the island Mefjärd in the archipelago of Stockholm. Mefjärd is about 3000 x 400 m in size, located 10 km from the eastern coast of Sweden. Measurements of air temperature was taken continuously between the 20/3 and 22/4 both by the shoreline and in the middle of the island. Sea temperature, wind and solar radiation were also measured. Statistical calculations were done and figures displaying air temperatures and other measured data were created. The result showed, among other things, that the air temperature by the shoreline was more stable and generally closer to the sea temperature than the air temperature in the middle of the island, and that the air temperature in the middle of the island was more sensitive to changes in sun radiation than the air temperature by the shoreline. These results were apparent even though the study was conducted on a small scale.
2

Reversible directed phase transfer of M4IIL4 and M4IIL6 cages

Georges, Maureen Claire Alma January 2017 (has links)
A major function assessed by Nature is the transport of a cargo between two different media, such as anions through cell membranes. Mimicking this function using complex systems is one of the biggest challenge of supramolecular chemistry. Metallo-organic cages are an important breakthrough in the encapsulation and transport of small molecules, providing a crucial platform for the development of systems chemistry. Binding a network member within a tetrahedral cage allows it to be hidden and then revealed upon receipt of a release signal, or transported as a cargo between spatially distant parts of a network. Larger capsules may also isolate subsystems from each other in the manner of vesicles. These dynamic architectures are synthesised by self-assembly, which involves the simultaneous formation of multiple coordinative and dynamic covalent linkages during the same overall synthetic process. Their shape and binding properties can be tuned by changing the subcomponents such as metals or ligands. Great progress has been reported in recent years in the development of three-dimensional cages that can interact with specific guest species, but there are limitations associated with the transport of these systems. Recent work by Nitschke et al. have successfully addressed practical separations problems by transporting a tetrahedral cage and its cargo from water into an ionic liquid layer. However, this system is not ideal as the process is triggered by an anion exchange not by a direct stimulus. This thesis reports the synthesis of an ionic liquid inspired tetrahedral system achieving reversible transport between water and an immiscible organic solvent driven by a change in temperature. Once the switchable capsules were obtained and characterised, their ability to move between different solvent phases upon heating was investigated. A capsule-mediated transport system as developed that is both directional and reversible. The flow of the capsule and its encapsulated cargo is directed using stimuli such as temperature modification. Ultimately an apparatus that allows the switchable capsules to move along a channel has been developed.
3

Thermorheology of living cells: impact of temperature variations on cell mechanics

Kießling, Tobias R., Stange, Roland, Käs, Josef A., Fritsch, Anatol W. 16 August 2022 (has links)
Upon temperature changes, we observe a systematic shift of creep compliance curves J (t) for single living breast epithelial cells. We use a dual-beam laser trap (optical stretcher) to induce temperature jumps within milliseconds, while simultaneously measuring the mechanical response of whole cells to optical force. The cellular mechanical response was found to differ between sudden temperature changes compared to slow, long-term changes implying adaptation of cytoskeletal structure. Interpreting optically induced cell deformation as a thermorheological experiment allows us to consistently explain data on the basis of time–temperature superposition, well known from classical polymer physics. Measured time shift factors give access to the activation energy of the viscous flow of MCF-10A breast cells, which was determined to be 80 kJ mol−1. The presented measurements highlight the fundamental role that temperature plays for the deformability of cellular matter. We propose thermorheology as a powerful concept to assess the inherent material properties of living cells and to investigate cell regulatory responses upon environmental changes.
4

Avaliação de bolsas de sangue de policloreto de vinila submetidas às variações de temperatura.

MOURA, Leandro Silva. 29 June 2018 (has links)
Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-06-29T20:25:24Z No. of bitstreams: 1 LEANDRO SILVA MOURA – DISSERTAÇÃO (UAEMa) 2015.pdf: 1388978 bytes, checksum: 0d032071aaa01d2baa1f746d3bbe2a17 (MD5) / Made available in DSpace on 2018-06-29T20:25:24Z (GMT). No. of bitstreams: 1 LEANDRO SILVA MOURA – DISSERTAÇÃO (UAEMa) 2015.pdf: 1388978 bytes, checksum: 0d032071aaa01d2baa1f746d3bbe2a17 (MD5) Previous issue date: 2015-02-27 / A introdução das bolsas plásticas de policloreto de vinila (PVC) para coleta e armazenamento de sangue e seus componentes constituiu um grande avanço no processo transfusional. O uso destas bolsas trouxe aos serviços de hemoterapia uma coleta, preparação e transfusão do sangue de forma mais rápida, segura e eficiente. A influência de processos extremos no processamento e armazenamento das bolsas de sangue, como variações de temperatura de esterilização de 115ºC a 120ºC, temperaturas de armazenamento de sangue de até -70ºC e sucessivas centrifugações de até 5000rpm, podem levar a alterações no material. Estas alterações podem causar ruptura das bolsas de sangue com perda de seu conteúdo, gerando com isso, riscos biológicos, prejuízos econômicos e aspectos sociais pela doação de sangue. Este trabalho teve como objetivo a avaliação das propriedades químicas e térmicas das bolsas de policloreto de vinila. As amostras de bolsas plásticas nacionais utilizadas para este estudo foram selecionadas no Sistema de Dados da ANVISA - DATAVISA entre as bolsas regularizadas. As bolsas constituídas de PVC foram caracterizadas por Espectroscopia na Região de Infravermelho com Transformada de Fourier (FTIR), Microscopia Eletrônica de Varredura (MEV), Espectroscopia por Energia Dispersa de raios X (EDS), Calorimetria Exploratória Diferencial (DSC) e Análise Termogravimétrica (TG). De acordo com os resultados observados no ensaio de FTIR, pode-se afirmar que todas as bolsas apresentaram os grupos funcionais característicos do PVC. O MEV mostrou uma superfície homogênea. O ensaio de EDS detectou os elementos químicos característicos do material estudado. A Análise Termogravimétrica demonstrou que as bolsas de ambos os fabricantes apresentaram perfil de degradação térmica similar iniciando por volta de 200ºC. Já o ensaio de DSC corroborou com o ensaio de TG, mostrando a degradação inicial também em 200ºC. Fundamentado pelos dados obtidos neste trabalho verificou-se que as bolsas obedecem a um mesmo critério de composição, possivelmente a recomendada pela Farmacopeia Europeia. / The introduction of plastic bags of polyvinyl chloride (PVC) for collection and storage of blood and blood components was a breakthrough in transfusion process. The use of these bags brought to transfusion services a collection, preparation and transfusion of blood more quick, safe and efficient. The influence of extreme processes in the processing and storage of blood bags, as sterilization temperature of 115 to 120 ° C, blood storage temperature to - 70°C and successive centrifugations of up to 5000rpm, can lead to changes in the material. These changes can cause ruptures of blood bags with the consequence of losing contents causing economic losses, biological risk and negative implications for voluntary donation. This research has the objective the chemical and thermal evaluation of polyvinyl chloride blood bags. The samples from national blood bags used for this research were selected through ANVISA database from regularized blood bags. The PVC blood bags were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy-Dispersive X-Ray Spectroscopy (EDS), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TG). According to the results observed on FTIR, it can be affirmed that all bags had the characteristic functional groups of PVC. The SEM showed a homogeneous surface. The EDS essay detected the characteristic chemical elements of the studied material. The Thermogravimetric Analysis has shown the bags from both manufacturers have similar thermal degradation profile starting around 200°C. The DSC essay confirmed with the TG essay also showing the initial degradation at 200 °C. Based on the data obtained in this work it was identified that the bags conform to the same standard composition, possibly recommended by the European Pharmacopoeia.

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