Neste trabalho analisamos algumas consequências físicas de uma cosmologia acelerada com interação no chamado setor cósmico escuro (energia escura + matéria escura fria). A componente de energia escura é representada por uma densidade de energia do vácuo que varia com o tempo e cuja lei de decaimento tem a seguinte forma: $\\Lambda = \\Lambda_0 + {3\\alpha}/{a^{2}}$, onde $\\Lambda_0$ é o termo de vácuo usual, $\\alpha$ é um parâmetro livre e $a(t)$ o fator de escala. Nesse contexto discutimos a tensão existente entre os dados de Supernovas (que preferem um Universo fechado, $\\Omega_{\\kappa} > 0$) e os dados da radiação cósmica de fundo que favorecem um Universo espacialmente plano ($\\Omega_{\\kappa} = 0$). Considerando que o termo variável simula uma curvatura (pois ambos possuem a mesma dependência no fator de escala), mostramos que sua contribuição atua no sentido de aliviar a tensão SNe Ia-CMB existente no modelo de concordância cósmica padrão ($\\Lambda CDM$, $\\alpha=0$). O modelo resolve o problema da idade do Universo e para $a>>1$, tal como ocorre com $\\Lambda CDM$, também evolui para um estágio de Sitter. O parâmetro $\\alpha$ é limitado através de uma análise estatística conjunta envolvendo dados de Supernovas, CMB ({\\it shift parameter}) e oscilações acústicas dos bárions (BAO). Separando o termo de vácuo em duas componentes ($\\Omega_{\\Lambda 0}$ e $\\Omega_{\\alpha 0}$) um teste $\\chi^{2}$ fornece os seguintes valores para o modelo plano: $\\Omega_{m0} = 0,27 \\pm 0,02$, $\\Omega_{\\Lambda 0} = 0,74 \\pm 0,02$ e $\\Omega_{\\alpha 0} = -0,01 \\pm 0,03$. / In this work we analyze some physical consequences of an accelerating cosmology endowed with interaction in the cosmic dark sector (dark energy + cold dark matter). The dark energy component is represented by a time-dependent vacuum energy whose decay law has the following form: $\\Lambda = \\Lambda_0 + {3\\alpha}/{a^{2}}$, where $\\Lambda_0$ is the standard vacuum term, $\\alpha$ is a free parameter and $a(t)$ is the scale factor. In this context we discuss the existing tension between Supernovas (SNe Ia, which prefer a closed Universe, $\\Omega_{\\kappa} > 0$) and the cosmic background radiation (CMB) data (which are favoring a spatially flat Universe, $\\Omega_{\\kappa} = 0$). By considering that the variable $\\Lambda$-term mimics a curvature (since both terms have the same dependence on the scale factor), we show that its contribution helps to alleviate the tension SNe Ia-CMB existing in the standard cosmic concordance model. The present model solves the age of the Universe problem and for $a>>1$, it also evolves to a de Sitter model as occur with the $\\Lambda CDM$ scenario. The contribution of the $\\alpha$ parameter is limited through a joint statistical analysis involving Supernovas, CMB ({\\it shift parameter}) and baryon acoustic oscillations (BAO). By separating the variable vacuum term in two components ($\\Omega_{\\Lambda 0}$ e $\\Omega_{\\alpha 0}$), a $\\chi^{2}$ test furnishes the following values for the free parameters of the flat model: $\\Omega_{m0} = 0,27 \\pm 0,02$, $\\Omega_{\\Lambda 0} = 0,74 \\pm 0,02$ and $\\Omega_{\\alpha 0} = -0,01 \\pm 0,03$.

Embora o congelamento apresente vantagens em relação a outros métodos de conservação de alimentos, o mesmo causa alterações sensoriais, principalmente em produtos de origem vegetal. O morango, uma fruta muito apreciada e com formas variadas de consumo, tem comportamento sazonal e apresenta como fator limitante para o congelamento sua estrutura frágil e sensível ao processo, o que causa alterações sensoriais. Tais alterações podem ser minimizadas com a incorporação de crioprotetores, como a trealose, um dissacarídeo que vem se destacando pelo seu efeito crioprotetor em produtos congelados e desidratados. O principal objetivo deste trabalho foi verificar o efeito crioprotetor da trealose incorporada através da impregnação a vácuo em soluções de diferentes concentrações (100, 300 e 500 g/L) em morangos submetidos ao congelamento e descongelamento. As condições de impregnação foram de 5 min, aplicando pressão de -650 mmHg e 10 min de tempo de relaxamento. As alterações provocadas pelo processo de impregnação bem como a verificação do efeito crioprotetor da trealose foram identificadas através de análise de cromatografia líquida de alta eficiência (High Performance Liquid Chromatography- HPLC), análise colorimétrica, análise de textura, determinação do teor de sólidos solúveis, determinação do teor de umidade e perda de massa (perda por gotejamento). Os resultados mostraram que a concentração da solução de trealose exerce influência significativa no teor de umidade, teor de sólidos solúveis e teor de trealose. As amostras tratadas com soluções mais concentradas não sofreram desidratação após descongelamento. O teor de trealose, após descongelamento, permaneceu constante em todas as amostras tratadas. Todas as amostras tiveram a mesma perda de massa após descongelamento (perda por gotejamento), porém a composição da massa diferiu entre elas. Amostras tratadas com a solução mais concentrada perderam sólidos enquanto que as amostras tratadas com a menos concentrada, perderam água. Na análise de textura, a introdução da trealose não influenciou a força máxima de pico nas amostras impregnadas. Após descongelamento, todas as amostras, exceto a tradada com solução de 500 g/L, sofreram amolecimento. A parte externa dos morangos não sofreu alterações de cor devido à introdução da trealose nem devido ao congelamento e descongelamento. Na parte interna dos frutos, ocorreram variações no parâmetro L* devido à impregnação e no parâmetro b*, devido ao congelamento e descongelamento. / Although freezing offers advantages to others food conservations process, it causes sensorial changes, mostly in vegetables products. The strawberry, a quite appreciated fruit, shows different ways of use, has seasonal behavior and is limited to freezing due the sensorial changes caused by its fragile structure to freezing process. These sensorial changes can be minimized by the incorporation of cryoprotectors, as trehalose, that is known by its cryoprotector effect during freezing and dehydration. The aim of this work was to verify the trehalose cryoprotector effect in frozen and thawed strawberries introduced by vacuum impregnation with different solutions (100, 300 and 500 g/L). The impregnation conditions were 5 min of applying pressure of -650 mmHg and after atmospheric pressure was restored, the sample was maintained within the solution for 10 min (these conditions were obtained from previous experiments). The alterations caused by the vacuum impregnation and the verification of the cryoprotector effect of trehalose were identified by High Performance Liquid Chromatography (HPLC), color analysis, texture analysis, soluble solids content, moisture content and drip loss. The results have shown that concentration of the trehalose solution had a significant influence on the moisture content, soluble solids and trehalose content of impregnated strawberries. The samples treated with more concentration solutions did not dehydrated after thawing. The trehalose content was the same in all treated samples after thawing. All the samples showed the same drip loss due to thawing although the composition of the mass was different among the samples. Samples treated with the most concentration solution lost trehalose while the sample treated with the least concentration solutions lost water. The introduction of trehalose did not affect the maximum peak force of the impregnated samples. The freezing and the thawing process caused the softening of the samples. This effect was not observed on the sample treated with solution of 500 g/L. The introduction of trehalose did not cause significant differences in all color parameters measured on the outside of the strawberries after impregnation and thawing. In the inside of the samples, there were variation in the L* parameter caused by the vacuum impregnations and in the b* parameter caused by the freezing and thawing process.

Neste trabalho analisamos algumas consequências físicas de uma cosmologia acelerada com interação no chamado setor cósmico escuro (energia escura + matéria escura fria). A componente de energia escura é representada por uma densidade de energia do vácuo que varia com o tempo e cuja lei de decaimento tem a seguinte forma: $\\Lambda = \\Lambda_0 + {3\\alpha}/{a^{2}}$, onde $\\Lambda_0$ é o termo de vácuo usual, $\\alpha$ é um parâmetro livre e $a(t)$ o fator de escala. Nesse contexto discutimos a tensão existente entre os dados de Supernovas (que preferem um Universo fechado, $\\Omega_{\\kappa} > 0$) e os dados da radiação cósmica de fundo que favorecem um Universo espacialmente plano ($\\Omega_{\\kappa} = 0$). Considerando que o termo variável simula uma curvatura (pois ambos possuem a mesma dependência no fator de escala), mostramos que sua contribuição atua no sentido de aliviar a tensão SNe Ia-CMB existente no modelo de concordância cósmica padrão ($\\Lambda CDM$, $\\alpha=0$). O modelo resolve o problema da idade do Universo e para $a>>1$, tal como ocorre com $\\Lambda CDM$, também evolui para um estágio de Sitter. O parâmetro $\\alpha$ é limitado através de uma análise estatística conjunta envolvendo dados de Supernovas, CMB ({\\it shift parameter}) e oscilações acústicas dos bárions (BAO). Separando o termo de vácuo em duas componentes ($\\Omega_{\\Lambda 0}$ e $\\Omega_{\\alpha 0}$) um teste $\\chi^{2}$ fornece os seguintes valores para o modelo plano: $\\Omega_{m0} = 0,27 \\pm 0,02$, $\\Omega_{\\Lambda 0} = 0,74 \\pm 0,02$ e $\\Omega_{\\alpha 0} = -0,01 \\pm 0,03$. / In this work we analyze some physical consequences of an accelerating cosmology endowed with interaction in the cosmic dark sector (dark energy + cold dark matter). The dark energy component is represented by a time-dependent vacuum energy whose decay law has the following form: $\\Lambda = \\Lambda_0 + {3\\alpha}/{a^{2}}$, where $\\Lambda_0$ is the standard vacuum term, $\\alpha$ is a free parameter and $a(t)$ is the scale factor. In this context we discuss the existing tension between Supernovas (SNe Ia, which prefer a closed Universe, $\\Omega_{\\kappa} > 0$) and the cosmic background radiation (CMB) data (which are favoring a spatially flat Universe, $\\Omega_{\\kappa} = 0$). By considering that the variable $\\Lambda$-term mimics a curvature (since both terms have the same dependence on the scale factor), we show that its contribution helps to alleviate the tension SNe Ia-CMB existing in the standard cosmic concordance model. The present model solves the age of the Universe problem and for $a>>1$, it also evolves to a de Sitter model as occur with the $\\Lambda CDM$ scenario. The contribution of the $\\alpha$ parameter is limited through a joint statistical analysis involving Supernovas, CMB ({\\it shift parameter}) and baryon acoustic oscillations (BAO). By separating the variable vacuum term in two components ($\\Omega_{\\Lambda 0}$ e $\\Omega_{\\alpha 0}$), a $\\chi^{2}$ test furnishes the following values for the free parameters of the flat model: $\\Omega_{m0} = 0,27 \\pm 0,02$, $\\Omega_{\\Lambda 0} = 0,74 \\pm 0,02$ and $\\Omega_{\\alpha 0} = -0,01 \\pm 0,03$.

This thesis investigates the application of plasma immersion ion implantation (PIII) to polymers. PIII requires that a high negative potential be applied to the surface of the material while it is immersed in a plasma. This presents a problem for insulating materials such as polymers, since the implanting ions carry charge to the surface, resulting in a charge accumulation that effectively neutralises the applied potential. This causes the plasma sheath at the surface to collapse a short time after the potential is applied. Measurements of the sheath dynamics, including the collapsing sheath, are performed using an electric probe. The results are compared to theoretical models of the plasma sheath based on the Child-Langmuir law for high voltage sheaths. The theoretical model predicts well the sheath dynamics for conductive substrates. For insulating substrates the model can account for the experimental observations if the secondary electron coefficient is modified, justified on the basis of the poly-energetic nature of the implanting ions. If a conductive film is applied to the insulator surface the problem of charge accumulation can be avoided without compromising the effectiveness of PIII. The requirement for the film is that it be conductive, yet transparent to the incident ions. Experimental results are presented which confirm the effectiveness of the method. Theoretical estimates of the surface potential show that a film of the order of 5nm thickness can effectively circumvent the charge accumulation problem. Efforts to produce and characterise such a film form the final two chapters of this thesis. The optimal thickness is determined to be near the percolation threshold, where a marked increase in conductivity occurs. Spectroscopic ellipsometry is shown to be an excellent method to determine the film thickness and percolation threshold non-invasively. Throughout this work cathodic vacuum arcs are used to deposit thin films and as a source of metal plasmas. The design and construction of a pulsed cathodic vacuum arc forms a significant part of this thesis. Investigations of the cathode spots and power supply requirements are presented.

Solar hydrogen has the potential to replace fossil fuels with a sustainable energy carrier that can be produced from sunlight and water via &quotewater splitting&quote. This study investigates the use of hematite (Fe&sub2O&sub3) as a photoelectrode for photoelectrochemical water splitting. Fe&sub2O&sub3 has a narrow indirect band-gap, which allows the utilization of a substantial fraction of the solar spectrum. However, the water splitting efficiencies for Fe&sub2O&sub3 are still low due to poor absorption characteristics, and large losses due to recombination in the bulk and at the surface. The thesis investigates the use of nanostructured composite electrodes, where thin films of Fe&sub2O&sub3 are deposited onto a nanostructured metal oxide substrate, in order to overcome some of the factors that limit the water splitting efficiency of Fe&sub2O&sub3. Doped (Si, Ti) and undoped Fe&sub2O&sub3 thin films were prepared using vacuum deposition techniques, and their photoelectrochemical, electrical, optical and structural properties were characterised. The doped Fe&sub2O&sub3 exhibited much higher photoelectrochemical activity than the undoped material, due to an improvement of the surface transfer coefficient and some grain boundary passivation. Schottky barrier modeling of Fe&sub2O&sub3 thin films showed that either the width of the depletion region or the diffusion length is the dominant parameter with a value around 30 nm, and confirmed that the surface charge transfer coefficient is small. An extensive review of the conduction mechanisms of Fe&sub2O&sub3 is presented. ZnO and SnO&sub2 nanostructures were investigated as substrates for the Fe&sub2O&sub3 thin films. Arrays of well-aligned high aspect ratio ZnO nanowires were optimised via the use of nucleation seeds and by restricting the lateral growth of the nanostructures. The geometry of the nanostructured composite electrodes was designed to maximise absorption and charge transfer processes. Composite nanostructured electrodes showed lower quantum efficiencies than equivalent thin films of Fe&sub2O&sub3, though a relative enhancement ofcollection of long wavelength charge carriers was observed, indicating that the nanostructured composite electrode concept is worthy of further investigation. The rate-limiting step for water splitting with Fe&sub2O&sub3 is not yet well understood and further investigations of the surface and bulk charge transfer properties are required in order to design electrodes to overcome specific shortcomings.

<p>Outokumpu Stainless tillverkar rostfri styckeplåt. ABB Industriunderhåll AB har sedan</p><p>11 år tillbaks i tiden ansvarat för underhållet på anläggningen i Degerfors åt avdelningen</p><p>Hot Rolled Plate. Hjälpmedel för att transportera och förflytta plåtar är vakuumlyftok och</p><p>en undersökning har gjorts om det finns möjlighet att modifiera vakuumlyftoken så att</p><p>bättre underhållsmässighet uppnås.</p><p>Två stycken äldre vakuumlyftok har modifierats med förslag på nya komponenter valda</p><p>för att få en standard både för nya och äldre vakuumlyftok.</p><p>Vakuumlyftok 173 (fr.1978): Ny vakuumvakt (PN7009), vakuummeter (AM80-N) och</p><p>filter (PIAB G3/8”).</p><p>Total kostnad för modifiering: 122 695 kr</p><p>Underhållskostnad (år 2007): 538 127 kr</p><p>Nytt vakuumlyftok (inköpspris): 700 000 – 1 200 000 kr</p><p>Nytt vakuumlyftok med antisvajsystem rekommenderas för att få ner</p><p>underhållskostnader som till stor del består av trasiga sugkoppar.</p><p>Vakummlyftok 332 (fr.1992): Ny vakuumvakt (PN7009).</p><p>Total kostnad för modifiering: 38 505 kr</p><p>Underhållskostnad (år 2007): 69 230 kr</p><p>Vakuumvakten är utgående och behöver ersättas med en ny.</p><p>Plåtar som anses vara problem att lyfta med vakuumlyftok är de med en tjocklek på</p><p>20 mm då det händer att dessa tappas. FEM-analyser på tre valda vakummlyftok har</p><p>gjorts i PRO/E Mechanica och Ansys som resulterat i följande:</p><p>Vakuumlyftok 173: Maximal plåtlängd ca 12 170 mm och maximalt utstick ca 2000 mm</p><p>Vakuumlyftok 332: Maximal plåtlängd +14 000 mm och maximalt utstick +1900 mm</p><p>Vakuumlyftok 457: Maximal plåtlängd ca 11 300 mm och maximalt utstick ca 1900 mm</p> / <p>Outokumpu Stainless manufactures stainless steel plates. ABB Industriunderhåll AB has</p><p>since 11 years been responsible for the maintenance of Hot Rolled Plate at Outokumpu,</p><p>Degerfors. Transportation of plates is made with the help of vacuum lifting beams.</p><p>Investigation has been made whether it is possible or not to modify vacuum lifting beams</p><p>to achieve better maintainability.</p><p>Two elderly vacuum lifting beams have been modified with proposals for new</p><p>components selected to achieve a standard for both new and older vacuum lifting beams</p><p>Vacuum lifting beam 173 (fr.1978): New underpressure switch (PN7009), vacuum gauge</p><p>(AM80-N) and vacuum filters (PIAB G3/8") .</p><p>Total cost of the modification: 122 695 SEK</p><p>Cost of maintenance (year 2007): 538 127 SEK</p><p>New vacuum lifting beam (purchase): 700 000 - 1 200 000 SEK</p><p>A new vacuum lifting beam with a swing compensating system recommends to</p><p>reduce maintenance costs of broken suction plates.</p><p>Vacuum lifting beam 332 (fr.1992): New underpressure switch (PN7009).</p><p>Total cost for modification: 38 505 SEK</p><p>Cost of maintenance (year 2007): 69 230 SEK</p><p>The underpressure switch is outgoing and needs to be replaced with a new one.</p><p>Plates that considered causing problems for vacuum lifting beams are the long plates with</p><p>a thickness of 20mm. Sometimes steel plates come loose which violates the safety. Three</p><p>selected vacuum lifting beams have been FEM-analyzed in Pro/E Mechanica and Ansys,</p><p>which resulted in the following.</p><p>Vacuum lifting beam 173: Max. plate length 12 170 mm and a maximum projecting</p><p>2000 mm</p><p>Vacuum lifting beam 332: Max. plate length +14 000 mm and a maximum projecting</p><p>+1900 mm</p><p>Vacuum lifting beam 457: Max. plate length 11 300 mm and a maximum projecting</p><p>1900 mm</p>

H.A. Haus. / "April 5, 1958"--Cover. "Presented at the Symposium on Electronic Waveguides, Polytechnic Institute of Brooklyn, April 8-10, 1958." / Bibliography: p. 131-132. / Army Signal Corps Contract DA36-039-sc-64637. Dept. of the Army Task 3-99-06-108 and Project 3-99-00-100.

S.J. Mason. / "August 25, 1953." / Army Signal Corps Contract DA 36-039 sc-100 Project 8-102B-0 Dept. of the Army Project 3-99-10-022

C.A. Stutt. / "March 26, 1949." / Bibliography: p. 18. / Army Signal Corps Contract No. W36-039-sc-32037 Project No. 102B Dept. of the Army Project No. 3-99-10-022

B. Chance, J.N. Thurston, P.L. Richman. / "Reprinted from the Review of scientific instruments, v. 18, no. 9, 610-616, Sept., 1947." / Includes bibliographical references.