A Chamomilla recutita L. é uma das plantas medicinais mais cultivadas no Brasil e no mundo. Os extratos da C. recutita são de interesse para as indústrias farmacêuticas e cosméticas, visto que estes apresentam atividades anti-inflamatória, antioxidante e adstringente. A ação terapêutica do extrato pode ser mais pronunciada que a ação terapêutica de um de seus ativos isolados. No entanto, a incorporação de um extrato em uma formulação pode ser difícil devido à baixa estabilidade dos extratos, bem como à possibilidade de gerarem instabilidade das formulações. Microencapsulando o extrato com um carreador é possível aumentar estabilidade do extrato quanto evitar instabilidade na formulação. Além disso, a microencapsulação é capaz de fornecer outras vantagens, como uma liberação controlada. Dois processos foram estudados como alternativas para a microencapsulação do óleo essencial e do extrato hidroalcoólico da C. recutita usando quitosana como carreador: o spray drying e o spray freeze drying. Planejamentos fatorais foram utilizados para determinar os fatores que mais influenciaram no diâmetro médio das micropartículas, eficiência de encapsulação e teor dos marcadores e rendimento do processo. A apigenina e a apigenina-7-glicosídeo foram usadas como marcadores do extrato hidroalcoólico e o óxido de bisabolol A foi usado como marcador do óleo essencial. Os processos de spray drying e spray freeze drying dos dois extratos foram otimizados e as micropartículas resultantes foram caracterizadas com relação ao diâmetro médio, rendimento do processo, teor e eficiência de encapsulação dos marcadores, atividade antioxidante in vitro, densidade, índice de Carr, fator de Hausner, umidade, morfologia, perfil de liberação n vitro e estabilidade. Os resultados mostraram que o processo de spray drying apresentou os melhores resultados para eficiência de encapsulação, com valores de aproximadamente 98%, 95% e 80% para apigenina, apigenina-7-glicosídeo e óxido de bisabolol A, respectivamente. As eficiências de encapsulação obtidas no processo de spray freeze drying foram de aproximadamente 59%, 58% e 38% para os mesmos marcadores, respectivamente. As micropartículas produzidas por spray freeze drying apresentaram formato irregular e poroso, enquanto as produzidas por spray drying apresentaram formato esférico e superfícies mais lisas, sem poros ou fissuras. Ao contrário do que ocorreu com o extrato hidroalcoólico, a perda do marcador do óleo foi elevada no processo de spray drying, com teor final de 35%. Os teores dos marcadores ficaram acima de 80% para o processo de spray freeze drying do óleo e acima de 90% para o extrato hidroalcoólico. As micropartículas produzidas por spray drying do extrato hidroalcoólico e do óleo e por spray freeze drying do extrato hidroalcoólico e do óleo apresentaram diâmetro médio de 5,1 ?m, 5,0 ?m, 31,0 ?m e 96,4 ?m, respectivamente. Ensaios de liberação in vitro mostraram que as micropartículas foram capazes de sustentar a liberação dos respectivos marcadores. Os estudos de permeação in vitro das micropartículas produzidas por spray drying do extrato hidroalcoólico também mostraram que estas foram capazes de sustentar a liberação. A microencapsulação proporcionou em todos os casos um aumento considerável da estabilidade. As micropartículas produzidas por spray drying do extrato hidroalcoólico apresentaram teores de marcadores no mínimo 50% maiores que o extrato puro após 90 dias. O spray freeze drying se mostrou como a melhor alternativa para produção de micropartículas de quitosana contendo o óleo essencial de C. recutita, enquanto o processo de spray drying se mostrou como uma ótima alternativa para microencapsulação do extrato hidroalcoólico da C. recutita. / Chamomilla recutita L. is one of the most cultivated medicinal plants in Brazil and around the world. Its extracts are important to both the pharmaceutical and cosmetics industries due to its therapeutic applications, such as an anti-inflammatory, antioxidant, and astringent. The therapeutic effects of an extract may be more pronounced than those of an isolated active compound. However, the incorporation of an extract in a formulation is difficult due to the low stability of extracts and the potential instabilities they may cause in formulations. Microencapsulating an extract in a carrier is a potential way of increasing the stability of an extract and avoiding instabilities in a formulation. Compound microencapsulation also brings other advantages, such as controlled release rates. Two processes were studied as alternatives to microencapsulating C. recutita essential oil and C. recutita hydroalcoholic extract using chitosan as a carrier: spray drying and spray freeze drying. Factorial designs were used to determine which process factors most influence the mean diameter, encapsulation efficiency and content of the chemical markers, and process yield. Apigenin and apigenin-7-glucoside were used as chemical markers for the hydroalcoholic extract and bisabolol oxide A was used as the chemical marker for the essential oil. The spray drying and spray freeze drying processes for both the oil and hydroalcoholic extract were optimized and the resulting microparticles were further characterized to determine mean diameter, process yield, marker encapsulation efficiency and content, in vitro antioxidant activity, density, Carr index, Hausner factor, water content, morphology, in vitro release profiles and stability. The results showed spray drying had the best encapsulation efficiency results, with about 98%, 95% e 80% of the apigenin, apigenin-7-glucoside and bisabolol oxide A content, respectively, inside the microparticles. The encapsulation efficiencies obtained in the spray freeze drying process were about 59%, 58% e 38% for the same chemical markers, respectively. Microparticles produced by spray freeze drying were irregular and porous, whereas microparticles produced by spray drying were spherical and fairly smooth, without porous or cracks. Contrary to what happened with the hydroalcoholic extract, oil marker content was low for spray dried microparticles, with final content at 35%. Chemical markers contents were above 80% for the oil and above 90% for the hydroalcoholic extract in spray freeze dried microparticles. Spray dried microparticles containing extract and oil and spray freeze dried microparticles containing extract and oil had mean diameter of 5.1 ?m, 5.0 ?m, 31.0 ?m and 96.4 ?m, respectively. In vitro release profiles showed all microparticles were able to sustain their respective marker release rates. In vitro permeation studies of spray dried microparticles containing hydroalcooholic extract also showed sustained release rates for the corresponding markers. Microencapsulation also provided considerable increase in C. recutita hydroalcoholic extract stability and C. recutita essential oil stability. After 90 days spray dried microparticles containing hydroalcoholic extract presented marker content 50% higher than the pure hydroalcoholic extract. Spray freeze drying was the best alternative to produce chitosan microparticles containing C. recutita essential oil, while spray drying was shown to be an excellent way to microencapsulate C. recutita hydroalcoholic extract in chitosan.

Thesis (M.S.)--Virginia Polytechnic Institute, 1942. / Includes bibliographical references (leaves 129-132). Also available via the Internet.

The project synthesizes phase pure Yttria particles using flame spray pyrolysis, and to experimentally determines the effect of various process parameters like residence time, adiabatic flame temperature and precursor droplet size on the phase of Yttria particles generated. Further, through experimentation and based on the understanding of the process, conditions that produce pure monoclinic Y2O3 particles were found. An ultrasonic atomization set-up was used to introduce precursor droplets (aqueous solution of yttrium nitrate hex hydrate) into the flame. A hydrogen-oxygen diffusion flame was used to realize the high temperature aerosol synthesis. The particles were collected on filters and analyzed using X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Individual process parameters (flame temperature, residence time, precursor concentration, precursor droplet size) were varied in continuous trials, keeping the rest of the parameters constant. The effect of the varied parameter on the phase of the product Yttria particles was then analyzed. Pre-flame heating was undertaken using a nozzle heater at variable power. Precursor solution concentrations of 0.026 mol/L, 0.26 mol/L, and 0.65 mol/L were used. Residence time was varied by means of burner diameter (9.5 mm and 1.6 mm ID). Large precursor droplets were removed by means of an inertial impactor. The higher flame temperatures and precursor heating favor the formation of monoclinic yttrium oxide. The fraction of the cubic phase is closely related to the particle diameter. All particles larger than a critical size were of the cubic phase. Phase pure monoclinic yttrium oxide particles were successfully synthesized. The end conditions included a precursor concentration of 0.65 mol/L, a pure hydrogen-oxygen flame and a 1.6 mm burner. The precursor droplets entrained fuel gas was passed through a round jet impactor and preheated at full power (130 VA). The particles synthesized were in the size range of 0.350 to 1.7 µm.

The project synthesizes phase pure Yttria particles using flame spray pyrolysis, and to experimentally determines the effect of various process parameters like residence time, adiabatic flame temperature and precursor droplet size on the phase of Yttria particles generated. Further, through experimentation and based on the understanding of the process, conditions that produce pure monoclinic Y2O3 particles were found. An ultrasonic atomization set-up was used to introduce precursor droplets (aqueous solution of yttrium nitrate hex hydrate) into the flame. A hydrogen-oxygen diffusion flame was used to realize the high temperature aerosol synthesis. The particles were collected on filters and analyzed using X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Individual process parameters (flame temperature, residence time, precursor concentration, precursor droplet size) were varied in continuous trials, keeping the rest of the parameters constant. The effect of the varied parameter on the phase of the product Yttria particles was then analyzed. Pre-flame heating was undertaken using a nozzle heater at variable power. Precursor solution concentrations of 0.026 mol/L, 0.26 mol/L, and 0.65 mol/L were used. Residence time was varied by means of burner diameter (9.5 mm and 1.6 mm ID). Large precursor droplets were removed by means of an inertial impactor. The higher flame temperatures and precursor heating favor the formation of monoclinic yttrium oxide. The fraction of the cubic phase is closely related to the particle diameter. All particles larger than a critical size were of the cubic phase. Phase pure monoclinic yttrium oxide particles were successfully synthesized. The end conditions included a precursor concentration of 0.65 mol/L, a pure hydrogen-oxygen flame and a 1.6 mm burner. The precursor droplets entrained fuel gas was passed through a round jet impactor and preheated at full power (130 VA). The particles synthesized were in the size range of 0.350 to 1.7 µm.

Abstract The combustion characteristics and the pollution of the exhausting products under various designing and operating conditions are studied in this research. In our experiments, the furnace fuel is diesel oil. By adjusting the flow rate of both axial air and tangential air the different equivalence ratios and swirl numbers can be obtained. The controlling ranges of the various experimental parameters include equivalence ratio from 0.8 to 1.1, swirl number from 0 to 1.0, recirculated flue gas from 0% to 12%, and jet spray angle 45?and 80? The effect of the controlling variables on the combustion characteristics and pollutant formations within combustion chamber are studied in this reseacher. A photographic technology is used to study the flame structures to help us understanding the behaviors of the flame under various operating condition. Form the experimental results, we find that the recirculation generated by swirl influence the produce temperature and its distribution with combustion chamber. The swirl is useful for flame expanding, and increases the mixing of fuel and air, so that the complete reaction can achieve near the burner. When the jet spray angle is 80? and swirl number is 0.6, the exhaust rate of NOx in the exhaust duct is the lowest, and the combustion in combustion chamber is the best. At equivalence ratio 0.9, the effects of the flow rate of the recirculating flue gason the flame structure and the exhaust emission is not too much. Our experiments display that the optimized operating condition is jet spray angle 80? swirl number 0.6 and flue gas recirculation 8%. NO can be reduced about 15~20% in this condition. When no swirl occurs, the color of flame displays white-yellow due to the burning of soot in this region. For the condition with swirl, the color of the outside flame displays orange-yellow. In primary combustion zone, the flame exhibits the red color which is due to the radiation of CO2 and water vapor.

In intermittently connected mobile networks (ICMNs), where most of the time there does not exist a complete path from source to destination, or such a path is highly unstable and may change or break after it has been found (or even while being found). This kind of environment may apply to wildlife tracking sensor networks or military networks, and node on this network must find a route and communicate with other nodes by the way of moving, because the base station is too far away or destroying. In order to achieve this purpose, researchers have suggested using flooding-based routing schemes. Although these ways have high probability of delivery, but they waste a lot of network resources. This thesis proposes a routing protocol in ICMNs named Spray and Hop, and it has adopted a kind of mechanism which is named Spray. The method can reduce network overhead, and broadcast efficiently at the same time by using one name little control packages named forwarding token. In addition, in order to improve the success rate of delivery, we still apply a kind of composite Utility-based mechanism. This mechanism is to select the next best candidate relay node through node's own information, not utilizing the way of direct transmission. Spray and Hop mechanism has highly scalability, that is, this mechanism has good performance in dense and sparse networks, and does not need extra network information. Simulation results show that Spray and Hop has good performance in packet transmissions and end-to-end delay indeed, comparing to other flooding-based mechanisms.

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1953. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 84-91).