Additive manufacturing (AM) is a growing process interesting many companies in many industries. Thereare multiple processes within the familty of AM, but this study focuses on laser blown powder (LBP). LBP involves a laser beam focused on the substrate with powder being blown into the laser beam. The laser beam melts both the powder and the surface of the substrate and as the laser beam moves and the melt pool solidies it leaves a bead of solid material behind. These beads are placed next to each other creating a layer which are then stacked, building the wanted geometry. As the method develops new materials are tested and this study analyses Haynes 282 powder onto Inconel 718 substrate. Multiple process parameters are involved in the LBP method and this study focuses on the impact of laser effect and scanning speed. Each value on the process parameters was inspired by previous reports with similar equipment and process. The laser effect ranges from 1600 W to 700 W, scanning speed ranges between 900 mm/min to 300 mm/min and the powder feeding rate was also varied from 4 g/min to 3 g/min. Each sample was built as a single bead and a multilayer specimen, which is ve layers and 16 beadswide at the bottom and 12 beads wide at the top. When analyzing the samples images from microscopes were mostly used for obtaining results. An image software called ImageJ allowed measurements in an image to obtain penetration depth or primary dendrite arm spacing. ImageJ also allowed measurements of porosity by turning the image binary and calculate the fraction of white and black. The results consists of numerical values and visual analysis of the bead geometry, minimum and maximum penetration, microstructure, porosity, hardness and cracks. The results show an increased bead width around 2 mm to 4 mm and decreased bead height around 0,2 mm to 0,7 mm of single beads with increased laser effect. Increased maximum penetration depth around, 200 μm to 500 μm, withincreased laser effect. More remelt between each deposited layer causing longer dendrites with increasinglaser effect. Porosity is decreased with an increased laser power, going from 0,04 % to 0,15 %. No distinct difference in hardness is observed between the samples, ranging between 255 HV to 310 HV. It is believed that aging causes the increased hardness right above the fusion zone. Cracks were found between dendrites and is believed to be caused by Laves-phases. Most results are comparable to previous similar studies, both as trends and numerical values. The statistics of the study is limited, meaning that all results should not be taken as granted but as a general guide line for more studies. The purpose and goals of the study has been met and completed.

Orientador: Oswaldo Durival Rossi Junior / Banca: Luiz Augusto do Amaral / Banca: Ana Maria Centola Vidal Martins / Resumo: A deterioração "blown pack" é caracterizada por abundante produção de gás, induzindo a completa distensão da embalagem durante o processo de estocagem sob refrigeração. Quando a embalagem é aberta, há um odor desagradável, levemente fecal. O gás presente na embalagem é composto por dióxido de carbono e hidrogênio e por vários tipos butíricos do metabolismo fermentativo. O objetivo deste experimento foi determinar possíveis causadores deste tipo de deterioração, quantificando as populações de bactérias da família Enterobacteriaceae, e caracterizando-as nos principais gêneros e espécies encontradas, o número de bactérias ácido-lácticas, a freqüência de Clostridium estertheticum e do Clostridium gasigenes, em carnes próprias para o consumo e em carnes que apresentaram a deterioração "blown pack". Para contagem e identificação dos membros da família Enterobacteriaceae e contagem de bactérias ácido-lácticas utilizou-se de técnicas microbiológicas clássicas. Já para pesquisa do C. estertheticum e C. gasigenes fez-se uso de técnicas de biologia molecular. Os microrganismos da família Enterobacteriaceae e bactérias ácido-láticas estavam presentes em populações elevadas e em maior número nas carnes com deterioração "blown pack". A espécie mais freqüentemente encontrada foi a Hafnia alvei. As amostras com deterioração "blown pack' apresentaram maior positividade para o C. estertethicum que amostras não deterioradas. Não houve diferença estatística de positividade para a presença do C. gasigenes entre amostras com deterioração "blown pack" e carnes não deterioradas. A principal forma de controle desta deterioração é a prevenção da contaminação da carne por material fecal. / Abstract: The "blown pack" spoilage is characterised by abundant gas production, leading to complete gross distention pack during refrigerated storage. When the packaging is opened, there is an unpleasant smell, lightly fecal. The gas present in the package is composed of carbon dioxide and hydrogen and also of several butyric types of metabolism fermentation. The purpose of this experiment was to determine possible causes of this spoilage type, quantifying the populations of bacteria of the family Enterobacteriaceae, and characterizing them in the major genera and species found, the number of lactic acid bacteria, the frequency of Clostridium estertheticum and Clostridium gasigenes in meat proper for consumption and meat which showed the "blown pack" spoilage. In order to enumerate and identify the members of the Enterobacteriaceae family, and to enumerate the lactic acid bacteria the procedure was classical microbiological techniques. However to search the C. estertheticum and C. gasigenes the procedure was molecular biology techniques. The microorganisms of the family Enterobacteriaceae and lactic acid bacteria were present in large populations and in greater numbers in meat with "blown pack" spoilage. The species which were found more often was the Hafnia alvei. Samples of "blown pack" spoilage had greater positive features for C. estertethicum than samples not damaged. There was no statistical difference of positive features for the presence of C. gasigenes between samples of "blown pack" spoilage and not damaged meat. The main way to control this spoilage is the prevention of contamination of meat by fecal material. / Mestre

Orientador: Pilar Rodriguez de Massaguer / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-17T01:44:38Z (GMT). No. of bitstreams: 1 Marques_AlessandraReginadaSilva_D.pdf: 2932913 bytes, checksum: a22dc65d180eab3917e06501dc994ccc (MD5) Previous issue date: 2010 / Resumo: Esta pesquisa teve por objetivos: a. enumerar os Clostridium psicrotróficos na forma vegetativa e esporulada presentes em cortes bovinos embalados a vácuo e resfriados, deteriorados e não deteriorados; b. caracterizar e identificar estes isolados bioquímica e geneticamente, comparando a precisão entre as duas metodologias; c. monitorar as possíveis fontes de Clostridium psicrotróficos junto à linha de produção em frigorífico no interior do estado de São Paulo; d. testar a habilidade dos isolados, identificados como Clostridium psicrotróficos e recuperados tanto a partir dos cortes bovinos quanto a partir de diversas etapas ao longo da linha de produção do frigorífico, em reproduzir o defeito de estufamento quando inoculados em altas populações em cortes bovinos e acondicionados em embalagens a vácuo e termoencolhimento sob condições praticadas pela indústria (6mBar/83°C-3s) ; e. avaliar se diferentes níveis de vácuo e termoencolhimento teriam efeito sobre as características do estufamento dos isolados que melhor reproduziram o defeito; f. analisar as características físicas das embalagens primárias e secundárias bem como possíveis danos após simulação de transporte para distância de 500km que pudessem favorecer a incidência de Clostridium psicrotrófico ou outras espécies contaminantes. Para as enumerações foram utilizadas 8 amostras deterioradas (6 contra-filés, 1 cupim bovino e 1 picanha bovina) e 5 não deterioradas (contra-filé), sendo analisados: exsudato (1mL), superfície (100cm2) e interior do corte cárneo (25g). As subamostras foram submetidas à enumeração de anaeróbios psicrotróficos vegetativos (Reinforced Clostridial Médium - RCA, 5% de sangue de carneiro desfibrilado estéril, 5% de glicose e 1,5% de Agar, RCM modificado), anaeróbios esporulados ativados pelo calor e pelo álcool, em Perfringens Agar Base (PAB, Oxoid, com 5% de solução de gema de ovo estéril, 15000UI polimixina/500mL e 6mg Kanamicina/500mL, PKP; 200mg cicloserina/500mL (PC)). Os 17 isolados caracterizados preliminarmente como Clostridium foram submetidos ao teste de sensibilidade ao metronidazol. Aqueles com halos de inibição = 3,5mm tiveram seu perfil fenotípico analisado mediante kit API 20A (bioMeriéux) e seu perfil genético analisado (sequênciamento do gene 16S rRNA). O isolamento no ambiente do frigorífico foi realizado a partir das fezes, couro e amostras provenientes do corredor de atordoamento e sangria, sala de desossa, esteiras de corte e embalagem, através de coleta por swabs acondicionados em caldo PYGS em anaerobiose por 4 semanas a 4 e 15°C. Após, as amostras foram plaquea das em meio RCA e SFP (Shahidi Ferguson Perfringens) por 1 mês, caracterizadas e isoladas as colônias diferenciadas e ainda submetidas a confirmação, de gênero, para Clostridium. Os 2 isolados, provenientes de cultivo a 4°C confir mados como Clostridium, foram identificados utilizando mesma metodologia descrita anteriormente para isolados provenientes do corte cárneo. O teste de habilidade de reprodução do defeito de estufamento foi realizado com 12 linhagens, isoladas na primeira etapa da pesquisa, sendo 10 provenientes de cortes cárneos (8 identificados como C.gasigenes e 2 como C.algidicarnis) e 2 isoladas da linha de produção em frigorífico (C.gasigenes). Este teste foi realizado sob condições praticadas na indústria (6mBar com termoencolhimento 83°C/3s), inoculando-se nas superfícies dos bifes ( 10x5x2cm) de contra-filé, 1mL de suspensão padronizada em 108UFC/mL, obtendo-se 106UFC/50cm2. A incubação dos cortes bovinos inoculados juntamente, com 2 controles positivos (inoculados com C.estertheticum) e 2 controles negativos (sem inoculo) foi conduzida a 2° e 15°C por 8 semanas. Os 3 isolados (2 provenien tes dos cortes cárneos ¿ C.algidicarnis e C.gasigenes e 1 proveniente do frigorífico ¿ C.gasigenes) que melhor reproduziram as características do estufamento, seguiram para testes de influência de diferentes níveis de vácuo (6 e 9mBar) e temperaturas de termoencolhimento (83, 84 e 87°C) sob o tempo para aparecimento e intensidade do defeito. Também foram avaliados os sistemas de embalagem primário e secundário a fim de detectar falhas em ambos os sistemas que pudessem favorecer a incidência de espécies de Clostridium psicrotróficas. Mediante teste de simulação de transporte (norma ASMD4169-08, para caminhões) simulou-se o efeito de um percurso de 500km sobre as embalagens primárias e secundárias. Nas carnes deterioradas foi notado esverdeamento, aumento nos valores de pH e odores putrefativos e butíricos. As enumerações de psicrotróficos anaeróbios vegetativos, nas amostras deterioradas, atingiram níveis altíssimos (1014UFC/mL de exsudato). Quanto às formas esporuladas ocorreu predominância das ativadas pelo calor (105UFC/mL), sendo também recuperadas nas amostras não deterioradas. Bacillus facultativos psicrotróficos foram a flora dominante nas amostras deterioradas e não deterioradas com 50 e 70%, respectivamente. Das 17 linhagens, provenientes dos cortes cárneos, suspeitas de serem Clostridium apenas 10 foram confirmadas, destas, apenas 4 apresentaram perfis fenotípico e genético coincidentes (C1I13ESUPPKP; C2I2EXRCM; C4I8RCMEX; C2I5EXCHPC, sendo as 3 primeiras C.gasigenes e a última C.algidicarnis). Destes 10, 8 foram identificadas como C.gasigenes e 2 como C.algidicarnis. É importante enfatizar que em apenas 3 das 8 amostras de cortes cárneos deteriorados analisados (com estufamento), foram recuperados Clostridium psicrotrófico, ou seja, nas demais amostras onde estas espécies não foram recuperadas, a microflora causadora do estufamento pode ser um grupo heterogêneo composto por Bacillus psicrotróficos facultativos, que nesta pesquisa corresponderam a 50% da contaminação para as amostras deterioradas e, muito provavelmente, bactérias ácido lácticas e enterobactérias, conforme já detectado, em pesquisa paralela utilizando as mesmas amostras. Nos ambientes do frigorífico, temperaturas de 15°C fo ram medidas em locais que deveriam estar com temperaturas entre 0-6°C ou no máximo 7°C. A partir das superfícies de contato do frigorífico, fezes e chão, foram recuperados 38 isolados. Destes, apenas 2, 1 recuperado do couro e outro do corredor de abate/esteira de corte (mesmo isolado encontrado nos dois ambientes), foram identificados como Clostridium, os demais foram caracterizados como Bacillus facultativos psicrotróficos. Estes 2 foram identificados como C.gasigenes. A ocorrência destes isolados na forma viável junto à esteira de corte representa grande risco a carne pois uma vez arrastado ao produto final será um potencial causador do defeito de estufamento. Quanto aos ensaios de reprodução do defeito de estufamento, observou-se que a temperatura de 15°C acelerou a tempo para aparecimento dos primeiros sinais de estufamento, passando de 30 dias a 2°C pa ra 4 dias a 15°C e o isolado que melhor e mais rapidamente reproduziu as características do estufamento foi o C2I5EXCHPC (C.algidicarnis), com produção de gás, proteólise e alterações de pH (de 5.5 para 7.5) após 4 dias/15°C e 30 dias/2°C. Resultados similares foram obtidos para o controle positivo (C.estertheticum). Os outros 2 isolados que também reproduziram rápida e intensamente o estufamento foram C2I8EXCHPC e LMI13CA/EC ¿ isolado a partir do corredor de abate/esteira de corte junto ao frigorífico, ambos identificados como C.gasigenes, cabendo esclarecer que o defeito, para estes dois isolados, não foi tão intenso quanto para o C2I5EXCHPC. Todos os isolados foram capazes de reproduzir o defeito de estufamento ao final de 8 semanas de incubação a 15°C, enquanto que, a 2°C, somente 5 tiveram esta capacidade. Assim, temperaturas de abuso de refrigeração (15°C) aceleram o tempo para aparecimento dos primeiros sinais de estufamento por Clostridium e a temperatura de 2°C não é capaz de impedir a ocorrência deste defeito. Amostras inoculadas com C2I5EXCHPKP (C.algidicarnis) e submetidas a termoencolhimento a 83°C e 84°C/6mBar apresentaram períodos similares para aparecimento dos primeiros sinais de deterioração (~14 dias), entretanto, aplicando termoencolhimento a 87°C, foi observado um incremento neste tempo para 4 semanas. Assim sendo, considerando-se o nível de vácuo de 6mBar (aplicado pela indústria) a deterioração somente seria retardada, mas não deixaria de existir, aplicando-se um termoencolhimento a 87°C/3s, provav elmente porque nesta condição as células mais termosensíveis são inativadas. Por outro lado, as amostras tratadas com condições similares de termoencolhimento mas com nível de vácuo de 9mBar, apresentaram decréscimo no tempo de deterioração de 14 para 4 dias quando se aplicou 83 e 84°C/3s, d emonstrando que este vácuo maior estimula espécies de Clostridium. Entretanto, nas amostras tratadas com termoencolhimento a 87°C os primeiros sinais de deterioração somente foram observados após 7 semanas a 1°C. Assim, a condição de vácuo/termoencolhimento que mais prolongou a vida de prateleira da carne, quando inoculada, foi 87°C/9mBar, mas esta condição não impediu o desenvo lvimento do C.algidicarnis e o tempo de atraso do defeito de estufamento ainda foi inferior ao prazo de vida útil do produto. As embalagens primárias e secundárias analisadas estavam de acordo com as especificações do fabricante. Quanto à simulação de transporte, após o percurso de 500km apenas 1 embalagem primária demonstrou alterações que pudessem favorecer a atividade de anaeróbios facultativos. Por esta pesquisa, observou-se coincidência entre a flora encontrada nas superfícies do frigorífico e a flora recuperada a partir das amostras deterioradas. Além disso, a condição mais severa de termoencolhimento e vácuo aplicados (87°C/3s/9mBar), somente foi capaz de retardar o tempo para aparecimento do defeito de estufamento não o impedindo. Mesmo este tempo maior ainda foi inferior ao prazo de validade do produto. Sendo assim, pode-se inferir que a prevenção do defeito de estufamento não deve residir apenas na eliminação de células vegetativas de ambientes de planta mas também na eliminação de esporos que, uma vez arrastados para a embalagem, poderão germinar tornandose potenciais causadores do defeito de estufamento, além, é claro, da manutenção de ambientes de produção e estocagem em temperaturas inferiores a 2°C e higiene adequada durante a manipulação das carcaças e retirada do couro. Em adição, ficou comprovado que o abuso de temperatura de refrigeração acelera o estufamento de embalagens no caso de espécies de Clostridium psicrotróficos estarem presentes, principalmente C.algidicarnis, e que, as condições de vácuo/termoencolhimento aplicadas atualmente pela maioria das indústrias (83°C/3s/6mBar) não se apres entam como barreira eficiente à prevenção do defeito de estufamento na carne bovina embalada a vácuo / Abstract: This research aimed at: a. to enumerate psychrotrophic clostridia vegetative and spores from spoiled and unspoiled chilled vacuum packed red meat; b. to characterize and identify the isolates biochemical and genetically, comparing precision between then; c. to determine possible preslaughter and processing sources of psychrotrophic clostridia causing spoilage of vacuum packed red meats; d. assessment of blowing ability of Clostridium isolates at industrial conditions (6mBar/83°C-3s); e. to evaluate different vacuum and heat shrinking treatments on blown characteristics of the best representative isolates; f. to analyze physical characteristics of primary and secondary packs as well as possible damages after transport simulation (500km) that could lead to psychrotrophic Clostridium and other contaminant species incidence. For enumeration 8 spoiled samples (6 strip-loin, 1 hump beef and 1 rump cap beef) and 5 unspoiled (strip-loin): drip (1mL), surface (100cm2) and deep tissue (25g), were analyzed. Sub-samples were analyzed for vegetative psychrotrophic anaerobes (Reinforced Clostridial Medium - RCA, 5% of sterile defibrinated sheep blood, 5% of glucose and 1.5% of Agar, modified RCM); sporeforming anaerobes were counted by alcohol and heat treatment on Perfringens Agar Base (PAB, Oxoid, containing 5% sterile egg-yolk solution, 15000UI polymixin/500mL e 6mg kanamycin/500mL, PKP; 200mg cycloserin/500mL (PC)). For the 17 isolates characteried as clostridia, metronidazole test was applied for genera determination of Clostridium, isolates with inhibition zones = 3.5mm were phenotypical (by API 20A ¿ bioMeriéux) and genetically (16S rRNA sequence) identified. The slaughterhouse survey was conducted from feces, leather, stunning aisle, boning room, meat cutting conveyor belt and packing conveyor belt by sterile swabs inoculated in PYGS medium, incubated anaerobically at 4 and 15°C/4 weeks. Afte r incubation, loopfuls of the enrichments were directly streaked onto the surface of RCA and SFP (Shahidi Ferguson Perfringes), incubated for a month and then the different colonies were characterized and forwarded to genera confirmation. The confirmation of blowing ability was conducted with 12 strains, isolated from first stage of this research: 10 from red meats (8 identified as C.gasigenes and 2 as C.algidicarnis) and 2 from slaughterhouse (C.gasigenes). This test was conducted under industrial practices (6mBar, 83°C/3s), inocul ating sterile strip-loin beefs surfaces (10x5x2cm) with 1mL of vegetative cells suspension (108CFU/mL), obtained 106CFU/50cm2. Inoculated samples with 2 positive controls (inoculated with C.estertheticum) and 2 negative controls (uninoculeted samples) were performed at 2 and 15°C / 8 weeks. The three best representative isolates (2 from meat samples ¿ C.algidicarnis e C.gasigenes and 1 from slaughterhouse ¿ C.gasigenes) were tested for blown characteristics conducted at different vacuum (6 and 9mBar) and heat shrinking (83, 84 and 87°C) treatments to evaluate the time to first sign of blow pack and spoilage magnitude. The primary and secondary pack systems were evaluated for failures that support the psychrotrophic Clostridium incidence. Effects of a 500km route on primary and secondary packs were measured by transport simulation test (ASMD4169-08, for trucks). Spoiled samples showed green discoloration, increase of pH values and putrefactive and butyric odors. For these samples, the psychrotrophic vegetative anaerobic counts reached very high levels (1014CFU/mL of drip). Concerning sporeforming the heat activated ones were predominant (105CFU/mL) and also were recovered for unspoiled samples. Psychrotrophic facultative Bacillus was the dominant flora in analyzed samples (50% for spoiled and 70% for unspoiled). From 17 Clostridium suspect strains only 10 were confirmed and these 4 showed phenothypical and genetical coincident profiles (C1I13ESUPPKP, C2I2EXRCM and C4I8RCMEX ¿ C.gasigenes; C2I5EXCHPC ¿ C.algidicarnis). Concerning these 10 Clostridium isolates, 8 were identified as C.gasigenes and 2 as C.algidicarnis. It is important to emphasize that only 3 spoiled samples provided psychrotrophic Clostridium isolation, others spoiled samples flora were heterogeneous group, composed by facultative psychrotrophic Bacillus, that represented 50% of isolates from spoiled samples, and, probably, lactic acid bacteria and enterobacteria, according to Chaves (2010), in parallel research using same samples. Inside the slaughterhouse, ambient temperatures of 15°C were observed for places that should be at 0-6°C or 7°C (maximum). From slaugther house ambient and contact surfaces 38 isolates were recovered but only 2, 1 from leather and 1 for stunning aisle/meat cutting conveyor belt (same isolate from both points), were identified as Clostridium, other were characterized as psychrotrophic facultative Bacillus. These 2 isolates were identified as C.gasigenes. The occurrence of viable Clostridium on meat cutting conveyor belt is a risk for meat as a focus of blown pack spoilage clostridia. For confirmation blowing ability tests, abuse temperature decrease the time to first sign of blown pack from 30 days at 2°C to 4 days at 15°C and the isolate that better reproduce (more quickly) the spoilage was C2I5EXCHPC (C.algidicarnis) showing gas production, proteolysis and pH alteration (5.5 to 7.5) after 4 days/15°C and after 30 days/2°C. Similar results we re obtained for C.estertheticum (positive control). In addition, others two isolates that also quickly reproduced the spoilage were C2I8EXCHPC and LMI13CA/EC ¿ isolated from stunning aisle/meat cutting conveyor belt slaughterhouse, both identified as C.gasigenes, however the defect was not intense than for samples inoculated with C2I5EXCHPC (C.algidicarnis). All isolates were capable to reproduce the spoilage at the end of 8 weeks at 15°C while at 2°C, only 5 iso lates reproduce the defect. So, abuse temperature (15°C) accelerate the onset of Clostridium mediate blown pack spoilage and 2°C does not control it. Samples inocu lated with C2I5EXCHPKP (C.algidicarnis) treated with heat shrink of 83 e 84°C/6mBar showed similar perio ds for initial spoilage (~14 days), but applying heat treatment at 87°C, it was observed an increase in t his period to 4 weeks. So, using vacuum at 6mBar (industrial practice) the deterioration is retarded, but does not cease to exist, applying heat shrink of 87°C/3s, probably because this condition inactivated some heat sensitive spores. On other side, samples treated with same conditions of heat shrink but applying vacuum at 9mBar showed a decrease of time to spoilage from 14 to 4 days at 83 and 84°C/3s as lower vacuum may stimulate clostridia germination. However, for samples heat shrinked at 87°C the initial spoilage was only observed after 7 weeks at 1°C. So the condition th at more extended meat shelf-life, when inoculated, was 87°C /9mBar, but this condition not prevented C.algidicarnis development and delay of blown pack was still smaller than product shelf-life. Primary and secondary packs were according to manufacture¿s specifications. Concerning transport simulation, after 500km only one primary pack showed alterations that could support facultative anaerobes activity. In this research, it was observed coincidence between slaughterhouses and spoiled samples flora. Besides, the more rigorous condition applied (87°C/3s/9mBar) was only capable to retard the blown pack not inhibit and the time to deterioration first sign was smaller than product shelf-life. In regard to this fact, the defect prevention of blown pack spoilage is associated with the elimination of vegetative and sporeformers from slaughterhouses that after germination process could induce spoilage, besides, temperature control of production lines and storage environment at = 2°C, must be apply. In addition, abuse temperature accelerate the onset of Clostridium mediate blown pack spoilage, if psychrotrophic clostridia are present, in special, C.algidicarnis, and the industry process condition (vacuum and heat shrink - 6mBar/83°C/3s) are not capable to prevent the spoilage, being necessary the application of more efficient hurdles as efficient sanitization of process line as well as reduce temperature of the refrigerate environment / Doutorado / Doutor em Ciência de Alimentos

Orientador: Arnaldo Yoshiteru Kuaye / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-17T12:04:20Z (GMT). No. of bitstreams: 1 Kawaichi_MarisaEmiko_M.pdf: 2974509 bytes, checksum: a8445980822038413faf0819712260d1 (MD5) Previous issue date: 2010 / Resumo: Casos de estufamento de carne bovina embalada à vácuo, causado por Clostridium estertheticum e Clostridium gasigenes, mantida sob temperatura de refrigeração vêm sendo observados em diversas regiões do Brasil, principalmente no Centro-Oeste, onde foi detectada a presença destes microrganismos em ambientes de abatedouros-frigoríficos. A complexidade analítica da técnica utilizada em pesquisas com esses microrganismos faz com que sejam escassos os trabalhos que visam o controle desse tipo de deterioração. Diante do exposto e considerando-se a importância da exportação de carne para a economia brasileira, o presente estudo teve como objetivo avaliar o efeito da inoculação de esporos de Clostridium estertheticum e Clostridium gasigenes em carne bovina embalada a vácuo e a eficiência esporicida in vitro do uso de ácidos orgânicos sobre estes microrganismos. Além disso, avaliou-se a capacidade de formação de biofilmes por C. estertheticum em superfície de aço inoxidável, e a eficiência de agentes químicos para sua remoção. Observou-se em carnes embaladas a vácuo, que C. gasigenes produzem maiores quantidades de gases, promovendo o estufamento da embalagem mais rápido em relação ao C. estertheticum. O primeiro indício da formação de bolhas por C. gasigenes foi observado aos 21 dias de incubação à temperatura de 7°C de armazenamento, enquanto que para C. estertheticum observou-se somente aos 35 dias na mesma temperatura. Notou-se uma produção de gás mais intensa à temperatura de armazenamento mais alta. Na carne inoculada com C. gasigenes houve um aumento progressivo no valor do pH, atingindo valores maiores em temperaturas mais elevadas, por volta de 49-77 dias, seguido por uma queda. Por sua vez, a inoculação com C. estertheticum não promoveu a mesma variação de pH, notando-se uma acentuada queda até 21-35 dias, seguido por um progressivo aumento. A utilização, de ácidos orgânicos mostrou reduzido ou nenhum efeito sobre esporos, de C. gasigenes e C. estertheticum, não sendo viável sua aplicação em cortes de carnes bovinas com a finalidade de inibir ou minimizar o blown pack. Observou-se que tanto a cepa de C. estertheticum padrão DSM 8809T quanto a cepa LHCE-13 isolada de equipamento (rolete de retirada do couro) foram capazes de formar biofilmes após 07 dias de contato com a superfície de aço inoxidável e os sanitizantes, ácido peracético (500mg/L) e peróxido de hidrogênio (200 mg/L) em contato por 15 minutos, mostraram-se eficientes no controle destes. São necessários programas de higienização mais rigorosos e efetivos para o controle de C. estertheticum e C. gasigenes nos abatedouros-frigoríficos, pois eles podem estar presentes no ambiente em forma de esporos e também como biofilmes, em locais com grande acúmulo de material orgânico ou em associações com outros microrganismos / Abstract: Occurrence of blown pack in vacuum packaged refrigerated meat caused by Clostridium estertheticum and Clostridium gasigenes have been reported by studies from several Brazilian states where these microorganisms were detected in abattoir environment such as the Midwestern region. Analytical complexity of the researches with C. estertheticum e C. gasigenes makes the studies to prevent or to control this spoilage scarce. For these reasons and it is considering the importance of Brazil¿s beef export to economy, the current study aim to assess the effect of inoculated spores of C. estertheticum and C. gasigenes on vaccum packaged meat and the efficiency in vitro of organic acid on reported microorganisms spores. Furthermore this study tested, for the first time, the ability of C. estertheticum to form biofilm in stainless steel surface and the use of some sanitizers to remove it. Results obtained from behavior analysis of C. estertheticum and C. gasigenes spores inoculated in vacuum packaged meat, showed us differences in growth between these microorganisms. C. gasigenes produced more amount of gas, leading the blown pack faster than C. estertheticum. The first evidence of gas bubble production by C. gasigenes was observed after 21 storage days at 7°C, whereas C. estertheticum started to produce bubbles only after 35 days at the same storage conditions. Gas production was intense in higher storage temperatures. Through the pH measurement it was possible verify that C. gasigenes increases progressively the pH, reaching maximum values after 49-77 days at higher storage temperatures, followed by decreasing. Moreover C. estertheticum do not cause variation in the pH, but it may be seen an accentuated decrease until 21-35 days, followed by an increase of the values, probably because of C. estertheticum ability to revert a falling pH through fast lactate fermentation, started when availability of glucose ends. Regarding to use of organic acids, there is reduced or none effect on C. gasigenes and C. estertheticum spores, it becomes this technique no viable to reduce or control blown pack in vacuum packaged meat. For the first time is demonstrate that C. estertheticum forms biofilm. Strains of C. estertheticum DSM 8809T and C. estertheticum LHCE-13 isolated from abattoir equipment (leather removal drums) are able to colonize surfaces of stainless steel in 07 days. The sanitizers peracetic acid (500mg/L) and hydrogen peroxide (200 mg/L) exposure in 5-25 day-old biofilms at least 15 minutes were effective to control them. Severe and effective hygienization program is needed to control C. estertheticum and C. gasigenes in abattoir environment, mainly because they may be present on equipment surfaces in spore forms and also through biofilm formation in places with high organic material presence / Mestrado / Engenharia de Alimentos / Mestre em Tecnologia de Alimentos

The diploma thesis focuses on the process of engagement in company IZONEX Group s.r.o. The company operates in construction industry. The thesis is divided into three parts. The first part mentions the theoretical backround, the second part is focused on the company’s current condition analysis. The third part of the thesis is dedicated to proposals that improve the engagement process.

This thesis work aimed at increasing the knowledge regarding phenomena occurring when gas is injected using a top-blown lance on to a bath. All results are based on physical modeling studies carried out both using low and high gas flow rates and nozzle diameters ranging from 0.8 mm to 3.0 mm. At the low gas flow rates, the penetration depth in the bath was studied. The experiments focused on studying the effect of nozzle diameter, lance height and gas flow rate on the penetration depth. It was found that the penetration depth increases with decreasing nozzle diameter, decreasing lance height and with increasing gas flow rate. The results were also compared with previous work. More specifically, it was studied how the previous published empirical relationships fitted the current experimental data. It was found that the relationships of Banks [1], Davenport [2], Chatterjee [3] and Qian [4] agreed well with the experimental data of this investigation for nozzle diameters of 2.0 mm and 3.0 mm. However, for smaller nozzle diameters there were considerable deviations. Therefore, a new correlation heuristically derived from energy conservation consideration was suggested and showed better agreement for small nozzle diameters. The experiments carried out at higher gas flow rates focused on the study of swirl motion. The effects of nozzle diameter, lance height, gas flow rate and aspect ratio on the swirl motion were investigated. The amplitude and period of the swirl as well as the starting time and the damping time of the swirl were determined. The amplitude was found to increase with an increased nozzle diameter and gas flow rate, while the period had a constant value of about 0.5 s for all nozzle diameters, gas flow rates and lance heights. The starting time for the swirl motion was found to decrease with an increased gas flow, while the damping time was found to be independent of gas flow rate, nozzle diameter, lance height and ratio of depth to diameter. / QC 20101217

Faraday rotation is a valuable tool for detecting magnetic fields. Here, the technique is considered in relation to wind-blown bubbles. In the context of spherical winds with azimuthal or split monopole stellar magnetic field geometries, we derive maps of the distribution of position angle (P.A.) rotation of linearly polarized radiation across projected bubbles. We show that the morphology of maps for split monopole fields are distinct from those produced by the toroidal field topology; however, the toroidal case is the one most likely to be detectable because of its slower decline in field strength with distance from the star. We also consider the important case of a bubble with a spherical sub-volume that is field-free to approximate crudely a “swept-up” wind interaction between a fast wind (or possibly a supernova ejecta shell) overtaking a slower magnetized wind from a prior state of stellar evolution. With an azimuthal field, the resultant P.A. map displays two arc-like features of opposite rotation measure, similar to observations of the supernova remnant G296.5+10.0. We illustrate how P.A. maps can be used to disentangle Faraday rotation contributions made by the interstellar medium versus the bubble. Although our models involve simplifying assumptions, their consideration leads to a number of general robust conclusions for use in the analysis of radio mapping data sets.

The ancient glass collection of the National Museum has more than 200 completely intact and so far - beside few exceptions - unpublished vessels which encompass a wide chronological framework from the 5th century BC until the end of antiquity. The core of the collection is composed of mold-blown and free-blown glass. The analysis of the collection offers a view into the history of the ancient glass production; examples of all kinds of production methods can be found in it - from a corn-formed glass, through a glass made by sagging into a form, and up to a mold-blown and free-blown glass. A great number of various decoration techniques and styles used in antiquity are represented in the collection; also, it contains vessels from various places within the Roman Empire, as well as outside of it. The major part of the work comprises blown glass from the Roman imperial period (chapter four), both free-blown and mold-blown, and from this virtually half are unguentaria of various types. Almost all types of vessel produced in this period are found in this chapter. The vessels were ordered according to types - e.g. open shapes, closed shapes and in the framework of these types they are arranged further - according to other criteria which create other sub-groups - as for example forms without a foot or on a...

The mixing of additives into a plastic is an extremely important step in the plastics industry, necessary for the manufacture of almost every conceivable product. Therefore the costs in developing new products can prove very expensive as the testing is usually carried out using full scale machines, usually using twin screw extruders because they are able to provide good dispersive and distributive mixing. This is particularly important when compounding difficult to disperse additives and nano-additives. What is required is a machine that can replicate the mixing abilities of a twin-screw extruder but on a laboratory scale. There have been attempts by industry to develop smaller machines, such as the Thermo Scientific HAAKE Minilab II Micro Compounder which processes on the scale of 7 cm3 of material volume. This can be too small for some needs and therefore a machine is required to produce material on the 10g to 100g scale. To this end a laboratory mixer of novel design was devised and its mixing performance was assessed using conductive carbon black and compared against the Thermo Scientific HAAKE Minilab II Micro Compounder, a 19 mm co-rotating twin-screw extruder and a 40 mm co-rotating twin-screw extruder. Carbon black was used because mixing performance can be assessed by measuring the minimum carbon loading necessary to induce electrical conductivity. It was found that the minimixer was able to induce electrical conductivity at loading of 5.75% but the comparison with the other machines proved difficult as the achievement of the threshold at which semi-conductivity occurred appeared independent of shear rate and mixing duration.

Abstract This thesis correlates rheological data into a non-linear blown film model that describes the stress and cooling-induced morphological transformations in the axial and flow profiles of the blown films. This will help to improve the physical and mechanical properties of the films in a cost effective way, which will in turn be of great benefit to the food and packaging industries. In this research, experimental and numerical studies of a blown film extrusion were carried out using two different low-density polyethylenes (LDPEs). In the experiment, the key parameters measured and analysed were molecular, rheological and crystalline properties of the LDPEs. In the numerical study, blown film simulation was carried out to determine the bubble characteristics and freeze line height (FLH). A new rheological constitutive equation was developed by combining the Hookean model with the well known Phan-Thien and Tanner (PTT) model to permit a more accurate viscoelastic behaviour of the material. For experimental verification of the simulation results, resins were processed in a blown film extrusion pilot plant using identical die temperatures and cooling rates as used in the simulation study. Molecular characteristics of both LDPEs were compared in terms of their processing benefit in the film blowing process. Based on the experimental investigation, it was found that molecular weight and its distribution, degree of long chain branching and cooling rate play an important role on melt rheology, molecular orientation, blown film processability, film crystallinity and film properties. Effect of short chain branching was found insignificant for both LDPEs. Statistical analysis was carried out using MINITAB-14 software with a confidence level of 95% to determine the effect of process variables (such as die temperature and cooling rate) on the film properties. Film properties of the LDPEs were found to vary with their molecular properties and the process variables used. Blown film model performance based on the newly established PTT-Hookean model was compared with that based on the Kelvin model. Justification of the use of PTT-Hookean model is also reported here using two different material properties. From the simulation study, it has been found that predictions of the blown film characteristics conformed very well to the experimental data of this research and previous studies using different materials and different die geometries. Long chain branching has been found as the most prominent molecular parameter for both LDPEs affecting melt rheology and hence the processability. Die temperature and cooling rate have been observed to provide similar effect on the tear strength and shrinkage properties of blown film for both LDPEs. In comparison to the Kelvin model, the PTT-Hookean model is better suited for the modelling of the film blowing process. It has also been demonstrated in this study that the PTT-Hookean model conformed well to the experimental data near the freeze line height and is suitable for materials of lower melt elasticity and relaxation time.