Universiẗat Diss., 2003--Tübingen.

Este trabalho teve como objetivo a utilização da tecnologia que emprega CO2 em estado supercrítico para estudar a formação de micropartículas de óleos essenciais encapsulados em polissacarídeos. O referido tema tem caráter inovador e inédito, já que a tecnologia supercrítica tem sido utilizada na formação e impregnação de partículas, principalmente de solutos sólidos, mas não tem sido aplicada na encapsulação de óleos essenciais. Os processos estudados, RESS (Rápida Expansão de uma Solução Supercrítica) ou o PGSS (Partículas de Soluções ou Suspensões em Gás Saturado) envolvem baixas temperaturas, possibilitando a não degradação de compostos voláteis e termossensíveis, tornando-os mais estáveis. Foram utilizados nesta pesquisa, polímeros que são, normalmente, utilizados no processo convencional de \"aroma em pó\". Mesmo sendo insolúveis ou parcialmente solúveis em CO2 supercrítico houve o intuito de aproveitar estudos comprovados de estabilidade de óleos essenciais encapsulados nestes materiais e ainda manter o custo do produto já que polissacarídeos tem, relativamente, baixo valor comercial, quando comparado aos polímeros que são empregados nos estudos que usam estes processos. Ensaios preliminares foram realizados com diferentes polímeros: Amido modificado, dextrina, maltodextrina e Purity Gum Ultra®, (gentilmente cedidos pela Corn Products, atual Ingredion Incorporated, Mogi Guaçu, SP, BR) no intuito de selecionar o material de parede mais apropriado para a microencapsulação do óleo essencial, representado pelo limoneno. Os resultados preliminares comprovaram que houve impregnação e possível microencapsulação do limoneno, observados e constatados através de análises de microscopia (óptica, eletrônica e de fluorescência confocal a laser) especialmente para Purity Gum Ultra®, a qual apresentou comportamento desejável como estabilidade da dispersão preliminar e morfologia, em comparação com os outros polissacarídeos testados (dextrina, amido modificado e maltodextrina). Os ensaios subsequentes (dimensionamento das partículas, microscopia eletrônica de varredura, microscopia confocal na presença de fluoresceína, estabilidade térmica e quantificação do teor de limoneno microencapsulado) determinaram definitivamente a eficiência da Purity Gum Ultra® como polímero mais apropriado como agente encapsulante, e com isso foi demonstrada a eficiência da técnica proposta para esta finalidade. Ainda, a técnica de microencapsulação empregada (PGSS) apresentou valores significativos na retenção do limoneno com até 86% quando a suspensão foi preparada utilizando etanol (EtOH) e lecitina de soja como surfactante, sendo um relevante indicativo de que o processo de microencapsulação via PGSS proporcionou eficiente retenção do limoneno, além de apresentar outras vantagens sobre os processos de microencapsulação convencionais utilizados na indústria de alimentos. O processo de microencapsulação que utiliza CO2 supercrítico é considerado como \"tecnologia limpa\", aliado a este solvente ser considerado abundante, barato e ambientalmente seguro. Neste estudo constatou-se que, além do emprego de baixa temperatura no processo (50 - 60º C), não houve necessidade do emprego de água na suspensão. / This study aimed to use the technology that employs CO2 in supercritical state to study the formation of microparticles encapsulated essential oils in polysaccharides. The supercritical technology has been used in impregnating particles, mostly of solid solutes, but has not been applied to the encapsulation of essential oils. The studied processes RESS (Rapid Expansion of a Supercritical Solution) or PGSS (Particles Solutions or Suspensions in Saturated Gas) involving low temperatures, not allowing degradation of volatile and polymers that are normally used in the conventional process of \"aroma powder\" were used in this study. Even though it is insoluble or partially soluble in supercritical CO2 proven in order to take advantage of the stability studies of encapsulated essential oils in these materials and still keep the cost of the product as polysaccharides have relatively low value when compared to the polymers that are employed in studies using these processes. Preliminary tests were performed with different polymers : modified starch, dextrin, maltodextrin and Purity Gum Ultra ®, ( kindly provided by Corn Products, Current Ingredion Incorporated, Mogi, SP, BR ) in order to select the most appropriate material for wall microencapsulation of essential oil, represented by limonene. Preliminary results showed that there was possible impregnation and microencapsulation of limonene, observed and recorded through analysis of microscopy (optical, electron and confocal) especially for Purity Gum Ultra ®, which showed desirable behavior such as dispersion and stability of primary morphology compared to other polysaccharides tested (dextrin, modified starch and maltodextrin). Subsequent tests (particle sizing, scanning electron microscopy, confocal microscopy in the presence of fluorescein, thermic stability and quantification of the limonene content microencapsulated definitely determined the efficiency of Purity Gum Ultra ® as the most appropriate polymer as agent encapsulating and it has been demonstrated the efficiency of the proposed technique for this purpose. The technique employed for microencapsulation (PGSS) showed significant amounts of limonene retention of up to 86% when the suspension was prepared using ethanol (EtOH) and soy lecithin as surfactant. Being indicative of a material that microencapsulation by PGSS provided efficient retention of limonene, besides other advantages over conventional microencapsulation processes used in the food industry. The microencapsulation process that uses CO2 supercritical is considered \"clean technology \" due to the low toxicity of CO2 besides this solvent is considered abundant, inexpensive and environmentally safe. In this study it was found that, in addition to using low temperature process ( 50 - 60º C ), there was no need for the use of water in suspension.

Este trabalho teve como objetivo a utilização da tecnologia que emprega CO2 em estado supercrítico para estudar a formação de micropartículas de óleos essenciais encapsulados em polissacarídeos. O referido tema tem caráter inovador e inédito, já que a tecnologia supercrítica tem sido utilizada na formação e impregnação de partículas, principalmente de solutos sólidos, mas não tem sido aplicada na encapsulação de óleos essenciais. Os processos estudados, RESS (Rápida Expansão de uma Solução Supercrítica) ou o PGSS (Partículas de Soluções ou Suspensões em Gás Saturado) envolvem baixas temperaturas, possibilitando a não degradação de compostos voláteis e termossensíveis, tornando-os mais estáveis. Foram utilizados nesta pesquisa, polímeros que são, normalmente, utilizados no processo convencional de \"aroma em pó\". Mesmo sendo insolúveis ou parcialmente solúveis em CO2 supercrítico houve o intuito de aproveitar estudos comprovados de estabilidade de óleos essenciais encapsulados nestes materiais e ainda manter o custo do produto já que polissacarídeos tem, relativamente, baixo valor comercial, quando comparado aos polímeros que são empregados nos estudos que usam estes processos. Ensaios preliminares foram realizados com diferentes polímeros: Amido modificado, dextrina, maltodextrina e Purity Gum Ultra®, (gentilmente cedidos pela Corn Products, atual Ingredion Incorporated, Mogi Guaçu, SP, BR) no intuito de selecionar o material de parede mais apropriado para a microencapsulação do óleo essencial, representado pelo limoneno. Os resultados preliminares comprovaram que houve impregnação e possível microencapsulação do limoneno, observados e constatados através de análises de microscopia (óptica, eletrônica e de fluorescência confocal a laser) especialmente para Purity Gum Ultra®, a qual apresentou comportamento desejável como estabilidade da dispersão preliminar e morfologia, em comparação com os outros polissacarídeos testados (dextrina, amido modificado e maltodextrina). Os ensaios subsequentes (dimensionamento das partículas, microscopia eletrônica de varredura, microscopia confocal na presença de fluoresceína, estabilidade térmica e quantificação do teor de limoneno microencapsulado) determinaram definitivamente a eficiência da Purity Gum Ultra® como polímero mais apropriado como agente encapsulante, e com isso foi demonstrada a eficiência da técnica proposta para esta finalidade. Ainda, a técnica de microencapsulação empregada (PGSS) apresentou valores significativos na retenção do limoneno com até 86% quando a suspensão foi preparada utilizando etanol (EtOH) e lecitina de soja como surfactante, sendo um relevante indicativo de que o processo de microencapsulação via PGSS proporcionou eficiente retenção do limoneno, além de apresentar outras vantagens sobre os processos de microencapsulação convencionais utilizados na indústria de alimentos. O processo de microencapsulação que utiliza CO2 supercrítico é considerado como \"tecnologia limpa\", aliado a este solvente ser considerado abundante, barato e ambientalmente seguro. Neste estudo constatou-se que, além do emprego de baixa temperatura no processo (50 - 60º C), não houve necessidade do emprego de água na suspensão. / This study aimed to use the technology that employs CO2 in supercritical state to study the formation of microparticles encapsulated essential oils in polysaccharides. The supercritical technology has been used in impregnating particles, mostly of solid solutes, but has not been applied to the encapsulation of essential oils. The studied processes RESS (Rapid Expansion of a Supercritical Solution) or PGSS (Particles Solutions or Suspensions in Saturated Gas) involving low temperatures, not allowing degradation of volatile and polymers that are normally used in the conventional process of \"aroma powder\" were used in this study. Even though it is insoluble or partially soluble in supercritical CO2 proven in order to take advantage of the stability studies of encapsulated essential oils in these materials and still keep the cost of the product as polysaccharides have relatively low value when compared to the polymers that are employed in studies using these processes. Preliminary tests were performed with different polymers : modified starch, dextrin, maltodextrin and Purity Gum Ultra ®, ( kindly provided by Corn Products, Current Ingredion Incorporated, Mogi, SP, BR ) in order to select the most appropriate material for wall microencapsulation of essential oil, represented by limonene. Preliminary results showed that there was possible impregnation and microencapsulation of limonene, observed and recorded through analysis of microscopy (optical, electron and confocal) especially for Purity Gum Ultra ®, which showed desirable behavior such as dispersion and stability of primary morphology compared to other polysaccharides tested (dextrin, modified starch and maltodextrin). Subsequent tests (particle sizing, scanning electron microscopy, confocal microscopy in the presence of fluorescein, thermic stability and quantification of the limonene content microencapsulated definitely determined the efficiency of Purity Gum Ultra ® as the most appropriate polymer as agent encapsulating and it has been demonstrated the efficiency of the proposed technique for this purpose. The technique employed for microencapsulation (PGSS) showed significant amounts of limonene retention of up to 86% when the suspension was prepared using ethanol (EtOH) and soy lecithin as surfactant. Being indicative of a material that microencapsulation by PGSS provided efficient retention of limonene, besides other advantages over conventional microencapsulation processes used in the food industry. The microencapsulation process that uses CO2 supercritical is considered \"clean technology \" due to the low toxicity of CO2 besides this solvent is considered abundant, inexpensive and environmentally safe. In this study it was found that, in addition to using low temperature process ( 50 - 60º C ), there was no need for the use of water in suspension.

The possibility of using supercritical carbon dioxide (scCO2) as the primary solvent in a spray process for producing superhydrophobic surfaces have been examined in this work. Using scCO2 as solvent will have considerably lower environmental impact compared to an organic solvent since scCO2 is considered a green solvent as it is non-toxic, non-flammable and recyclable. To be able to work at the pressures needed to reach the supercritical state of carbon dioxide, a high-pressure technique called rapid expansion of supercritical solutions (RESS) has been used to produce the coatings. Fluorinated compounds are often used when producing superhydrophobic coatings due to their intrinsic water repellent properties, but generally these compound do not degrade in nature. Due to this, a wax and a biodegradable polymer have been used as the coating materials in this work. Two RESS set-ups were used to spray a polymer from solutions of scCO2 and acetone. The first system was based on a continuous flow of the solvent mixture and the polymer particles were collected on silica surfaces. Some of the coatings had superhydrophobic properties and the limitation with this technique was the loss of particles between the nozzle and the surface. In the second set-up, RESS was combined with electrostatic deposition (ED) to improve the particle collection. Different processing parameters were examined and most of the RESS-ED sprayed surfaces were superhydrophobic. This was demonstrated by high contact angles against water, low contact angle hysteresis and low tilt angles at which a water droplet rolls off the surface. It was also shown that the surface structures created when spraying using RESS-ED induced the important two-level roughness that was needed to achieve superhydrophobicity. A semi-continuous process for scaling-up the RESS system when spraying the wax has been developed. Temperature and pressure was investigated to find the highest solubility of the wax in scCO2, and 250 bar and 67 °C resulted in the largest amount of sprayed wax. It was also shown that the system is suitable for spray-coating the wax on different substrates such as glass, paper, aluminium etc. since all of these surfaces showed superhydrophobic properties. The wear resistance of the coatings were examined by different methods. Scratch resistance, vertical compression and the friction between the surface and a finger were analysed. The polymer coated surfaces showed a larger robustness compared with the wax surfaces in the scratch tests. The superhydrophobicity was lost for the wax coatings exposed to compression loads above 59 kPa and in the frictions test, one finger stroke over the coating destroyed the surface roughness. Finally, the wax surfaces were investigated as coating barriers to protect steel from corrosion. The superhydrophobic coating was stable up to 10 days before corrosion of the steel started. / <p>QC 20140922</p>

Diese Arbeit zeigt die Verwendung ueberkritischer Fluide als analytisches Werkzeug fuer den Transport einer Gruppe nichtfluechtiger Molekuele, naemlich Nucleobasen, in die Gasphase. Das am haeufigsten verwendete ueberkritische Fluid ist Kohlendioxid, welches sich jedoch als zu ineffizient bei der Aufloesung von Nucleobasen herausstellte. Deshalb wurde ein Gemisch aus Ethylen mit Ethanol als Cosolvens als ueberkritisches Loesungsmittel verwendet. Für die Erkennung des kritischen Punktes reiner Fluide oder verduennter Fluidmischungen wurde eine neue Methode entwickelt. Die Verschiebung des kritischen Punktes von Ethylen durch Zugabe von Ethanol wurde experimentell ermittelt und mit der Zustandsgleichung von Soave Redlich Kwong in Beziehung gesetzt. Fuer einen Molenbruch des Cosolvens Ethanol von 0.054 erhoeht sich die kritische Temperatur nur um 5,5 C, wohingegen die Theorie eine Erhoehung um 10 C vorhersagt. Fuenf biologisch relevante Nucleobasen wurden mit Hilfe von 3% Ethanol als Cosolvens in ueberkritischem Ethylen geloest. Die Zusammensetzung des Ueberschall-Molekularstrahles der expandierten Loesung wurde mit einem Quadrupol-Massenspektrometer quantitativ analysiert. Das Signalverhaeltnis der Nucleobasen zu Ethylen lag in der Groessenordnung von 10^-4 bis 10^-5. Diese Nucleobasen wurden auch auf Oberflaechen abgeschieden, sowohl durch Hochdruckexpansion der ueberkritischen Loesungen, als auch durch Verdampfung von alkoholischen Loesungen (nach der ’Drop Casting’ Methode). Die dabei entstehenden Morphologien wurden ex-situ mittels Rasterkraftmikroskopie untersucht. Die Ursachen dieser Unterschiede werden anhand der relevanten Nukleationsmechanismen diskutiert. / This work highlights the use of supercritical fluids (SCF) as an analytical tool for the transfer of a group of non-volatile molecules, namely nucleobases, into the gas phase. The most commonly used SCF carbon dioxide was found inefficient in dissolving the nucleobases. Therefore, a mixture of ethylene (p_c = 50.6 bar and T_c = 9.35 C) with a cosolvent was used as the SC solvent. A new bracketing method was developed for detecting the critical point (CP) of pure fluids and diluted mixtures of fluids. The shift in CP of ethylene on addition of ethanol was determined and related to theoretical calculations by using the Soave Redlich Kwong equation of state. Comparing the experimental results to theoretical methods for calculating the CP showed large deviations. The critical temperature shifted by only 5.5 C when the mole fraction of the cosolvent i.e. ethanol was 0.054. Five biologically relevant were dissolved in SC ethylene using 3% of ethanol as cosolvent. The supersonic molecular beam composition of the expanded solution was analyzed quantitatively using a quadrupole mass spectrometer and the ratio of the nucleobases to ethylene in the beam was found to be of the order of 10^-4 to 10^-5. Surface deposition of the nucleobases through SCF solutions was carried out and the morphology was recorded using Atomic Force Microscopy. Remarkable differences were observed while comparing the morphology obtained after deposition using rapid expansion of supercritical solutions (RESS) and drop casting method. These differences are discussed in terms of diffusion, rate of evaporation of the solvent, degree of supersaturation, and the nucleation process.

Techn. Universiẗat, Diss., 2002--Darmstadt.

Before Responsive Web Design (RWD) it was common to create fixed-width websites. In recent years the standard way of creating responsive websites is by some of the fundamental aspects of RWD on the client-side. But can it be worth using RWD with components sent from a server by detecting the device and send component-specific material as to lessen some of the resources of the page? Tests have been made for this purpose with Google Lighthouse’s performance audits in mobile and desktop mode between four almost identical websites. These tests measures which website will receive better load-time performance results viewed from an emulated smartphone with a 3G/4G connection (mobile) and an emulated desktop PC with a 10 Mbps of connection (desktop). Each website consists of two pages, one with lesser resources (&lt; 1 MB, known as index.html), the other with larger resources (24.3 MB, known as gallery.html). All four websites are responsive and built after the main pillars of RWD. Two websites does not have any optimization while two websites have added image optimization. One of the two websites in each category, image-optimized and unoptimized, is a server-based component website. This means, it will use asynchronous calls to a server to get specific components for the specific viewport.  In the tests performed, between the unoptimized websites, one client-based (CRWDu), the other server-based (SRWDu), on index.html, the CRWDu website scored best in mobile and got a slightly better result in desktop mode. On gallery.html, the SRWDu website received the best results in both modes, mobile and desktop. Between the image-optimized websites, one client-based (CRWDo), the other server-based (SRWDo), the CRWDo website on index.html, had a slightly better result in mobile and a worse result in desktop mode. On gallery.html, the SRWDo website had a much better result in both mobile and desktop mode.