Potentialunterstützte Herstellung von Faserverbundwerkstoffen

Abstract The development of continuous fibre reinforced oxide/oxide-ceramic matrix composite has increased in the last years due to their degradation resistance in oxidation environments and their outstanding thermo-mechanical properties. Their application is of interest for example in components for combustions chambers, heat exchangers or in the aerospace industry. The very difficult and expensive manufacturing of ceramic matrix composites reinforced with multi-fibre layers justifies the application of the electrophoretic infiltration technique (EPI) to produce the matrix. The materials used in this work for EPI experiments are Nextel(TM) 720 fibre mats as reinforcement and alpha-Al2O3 powder as matrix. The obtained results of application of the electrophoretic deposition method are described and interpreted for this material combination. The principal part of this work describes the mechanism of the electrophoretic deposition (EPD). A subsequent section explains in a proposed hypothesis the behaviour of the system alpha-Al2O3/Nextel(TM) 720. This model was verified by the experimental results. Moreover two techniques, based on the EPI, are described. They are called lamination method and simultaneous multilayer infiltration method. The results of the simultaneous multilayer infiltration method show a completely filling of matrix powder into six fibre mats obtained in one EPI step. For this reason it is confirmed that the method is much more convenient than the conventional slurry infiltration to produce multilayer ceramic matrix composites. The sintered composite samples exhibit a fibre volume fraction of 45 % and a porosity of approx. of 30 %. The fabricated ceramic matrix composite samples showed pseudo-ductile fracture behaviour and exhibit a weak bonding at the interface between fibres and matrix.Die Entwicklung von langfaserverstärkten Oxid/Oxid-Verbundwerkstoffen hat in den letzten Jahren wegen der Oxidationsbeständigkeit und der guten thermomechanischen Eigenschaften dieser Werkstoffe stark zugenommen. So sind sie bspw. für Bauteile in Brennkammern, Wärmetäuschern oder in der Luft- und Raumfahrt von Interesse. Die schwierige und teure Fabrikation von Verbundwerkstoffen mit mehreren Gewebelagen begründet die Anwendung des elektrophoretischen Infiltrationsverfahrens (EPI) zur Herstellung der Matrix. Bei dem EPI-Verfahren wurden Fasergewebe Nextel(TM) 720 als Verstärkungsmaterial und alpha-Al2O3 als Matrixmaterial verwendet. Die Ergebnisse der elektrophoretischen Infiltration werden speziell für diese Materialkombination dargestellt und interpretiert. Der Hauptteil dieser Arbeit widmet sich den Reaktionsabläufen bei der elektrophoretischen Infiltration. Diesbezüglich wurde für das System alpha- Al2O3/Nextel(TM) 720 eine Arbeitshypothese aufgestellt und diese experimentell untersetzt. Darüber hinaus wurden zwei Techniken, die auf der EPI-Technik basieren, entwickelt und erprobt. Sie werden in dieser Arbeit als Laminationsverfahren und Mehrlageninfiltrationsverfahren bezeichnet. Die Ergebnisse zeigen, dass beim Mehrlageninfiltrationsverfahren die simultane elektrophoretische Infiltration eine vollständige Ausfüllung der Fasernzwischenräume mit Matrixpartikeln für bis zu sechs Gewebelagen ermöglicht. Damit ist dieses Verfahren der bekannten Schlickertechnik deutlich überlegen. Die im Labor hergestellten Sinterproben haben einen Faseranteil von 45 % und eine Porosität von ca. 30 %. Sie zeigen das typische quasiduktile Bruchverhalten für keramische Verbundwerkstoffe mit einer schwachen Faser-Matrix-Bindung

Plan de marketing de Schiaffino Gastronómica Catering

Schiaffino Gastronómica Catering (SGC) es una empresa que brinda el servicio mencionado a clientes corporativos y personas naturales. En el presente documento presentaremos la situación actual de SGC en la que, si bien se presenta como una empresa rentable y con cierto nivel de prestigio, ha visto estancado su crecimiento por falta de posicionamiento y reconocimiento, además de que no se ha establecido una gestión de negocio clara y enfocada en el crecimiento. La siguiente tesis analiza este problema de fondo y plantea reposicionar la marca de la compañía basándose en tres pilares: Servicio personalizado, uso de insumos orgánicos, orientación social. De acuerdo con el estudio de mercado realizado, se aprecia que la tendencia global basada en el consumo de productos orgánicos está tomando relevancia también en el Perú, y cada vez son más las personas preocupadas por su bienestar y por el consumo de productos saludables. Es en este posicionamiento donde proponemos que SGC debe enfocar su estrategia de diferenciación y desarrollar este creciente nicho mediante la prestación de un servicio personalizado, teniendo al cliente como foco de su atención adaptándose a sus necesidades, pero promoviendo la orientación social que tiene la empresa, en la que integran a la comunidad campesina, no solo en la cadena de producción, sino también en la justa repartición de beneficios. En este sentido, se plantean actividades claves e inversiones que faciliten la difusión de la marca generando reconocimiento y expansión de la propuesta a nuevos y potenciales clientes que puedan ver atractivo el servicio que SGC ofrece; desta forma hacer crecer el nicho de mercado al cual la empresa enfoca sus servicios. La hipótesis que planteamos es que si con una adecuada gestión de operación, con un reposicionamiento de la marca Schiaffino Gastronómica Catering, y con inversión estratégica enfocada en incrementar la cantidad de prestaciones del servicio y en la retención de clientes satisfechos, logremos alcanzar un crecimiento sostenible y orgánico que permita incrementar la rentabilidad de los accionistas, fortaleciendo la compañía

An assessment of orofacial clefts in Tanzania

<p>Abstract</p> <p>Background</p> <p>Clefts of the lip (CL), the palate (CP), or both (CLP) are the most common orofacial congenital malformations found among live births, accounting for 65% of all head and neck anomalies. The frequency and pattern of orofacial clefts in different parts of the world and among different human groups varies widely. Generally, populations of Asian or Native American origin have the highest prevalence, while Caucasian populations show intermediate prevalence and African populations the lowest. To date, little is known regarding the epidemiology and pattern of orofacial clefts in Tanzania.</p> <p>Methods</p> <p>A retrospective descriptive study was conducted at Bugando Medical Centre to identify all children with orofacial clefts that attended or were treated during a period of five years. Cleft lip and/or palate records were obtained from patient files in the Hospital's Departments of Surgery, Paediatrics and medical records. Age at presentation, sex, region of origin, type and laterality of the cleft were recorded. In addition, presence of associated congenital anomalies or syndromes was recorded.</p> <p>Results</p> <p>A total of 240 orofacial cleft cases were seen during this period. Isolated cleft lip was the most common cleft type followed closely by cleft lip and palate (CLP). This is a departure from the pattern of clefting reported for Caucasian and Asian populations, where CLP or isolated cleft palate is the most common type. The distribution of clefts by side showed a statistically significant preponderance of the left side (43.7%) (χ²= 92.4, p < 0.001), followed by the right (28.8%) and bilateral sides (18.3%). Patients with isolated cleft palate presented at very early age (mean age 1.00 years, SE 0.56). Associated congenital anomalies were observed in 2.8% of all patients with orofacial clefts, and included neural tube defects, Talipes and persistent ductus arteriosus.</p> <p>Conclusions</p> <p>Unilateral orofacial clefts were significantly more common than bilateral clefts; with the left side being the most common affected side. Most of the other findings did not show marked differences with orofacial cleft distributions in other African populations.</p

Head and Neck Non-Melanoma Skin Cancer Treated By Superficial X-Ray Therapy: An Analysis of 1021 Cases

To report a single-institutional experience with the use of Superficial X-Ray Therapy (SXRT) for head and neck non-melanoma skin cancer (N-MSC) and to compare outcomes by prescribed fractionation schedules.The medical records of 597 patients with 1021 lesions (720 BCC, 242 SCC, 59 SCC in situ) treated with kilovoltage radiation from 1979-2013 were retrospectively reviewed. The majority of patients were treated according to 1 of 3 institutional protocols based on the discretion of the radiation oncologist: 1) 22 x 2.5 Gy; 2) 20 x 2.5 Gy; 3) 30 x 2.0 Gy. "T" stage at first presentation was as follows: Tis (59); T1 (765); T2 (175); T3 (6), T4 (9); Tx, (7). All patients were clinical N0 and M0 at presentation. Chi-square test was used to evaluate any potential association between variables. The Kaplan-Meier method was used to analyze survival with the Log Rank test used for comparison. A Cox Regression analysis was performed for multivariate analysis.The median follow up was 44 months. No significant difference was observed among the 3 prescribed fractionation schemes (p = 0.78) in terms of RTOG toxicity. There were no failures among SCC in situ, 37 local failures (23 BCC, 14 SCC), 5 regional failures (all SCC) and 2 distant failures (both SCC). For BCC, the 5-year LC was 96% and the 10-year LC was 94%. For SCC the corresponding rates of local control were 92% and 87%, respectively (p = 0.03). The use of >2.0 Gy daily was significantly associated with improved LC on multivariate analysis (HR: 0.17; CI 95%: 0.05-0.59).SXRT for N-MSC of the head and neck is well tolerated, achieves excellent local control, and should continue to be recommended in the management of this disease. Fractionation schedules using >2.0 Gy daily appear to be associated with improved LC