3 resultados para Injection molding of plastics

em Helda - Digital Repository of University of Helsinki


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The purpose of this dissertation was to study the applicability of minced autologous fascia graft for injection laryngoplasty of unilateral vocal fold paralysis (UVFP). Permanence of augmentation and host versus graft tissue reactions were of special interest. The topic deals with phonosurgery, which is a subdivision of the Ear, Nose and Throat-speciality of medicine. UVFP results from an injury to the recurrent or the vagal nerve. The main symptom is a hoarse and weak voice. Surgery is warranted for patients in whom spontaneous reinnervation and a course of voice therapy fails to improve the voice. Injection laryngoplasty is a widespread surgical technique which aims to restore glottic closure by augmenting the atrophied vocal muscle, and also by turning the paralyzed vocal fold towards midline. Currently, there exists a great diversity of synthetic, xenologous, homologous, and autologous substances available for injection. An autologous graft is perfect in terms of biocompatibility. Free fascia grafts have been successfully used in the head and neck surgery for decades, but fascia had not been previously applied into the vocal fold. The fascia is harvested from the lateral thigh under local anesthesia and minced into paste by scissors. Injection of the vocal fold is performed in laryngomicroscopy under general anesthesia. Three series of clinical trials of injection laryngoplasty with autologous fascia (ILAF) for patients with UVFP were conducted at the Department of Otorhinolaryngology of the Helsinki University Central Hospital. The follow-up ranged from a few months to ten years. The aim was to document the vocal results and possible morbidity related to graft harvesting and vocal fold injection. To address the tissue reactions and the degree of reabsoprtion of the graft, an animal study with a follow-up ranging from 3 days to 12 months was performed at the National Laboratory Animal Center, University of Kuopio. Harvesting of the graft and injection was met with minor morbidity. Histological analysis of the vocal fold tissue showed that fascia was well tolerated. Although some resorption or compaction of the graft during the first months is evident, graft volume is maintained well. When injected deep and laterally into the vocalis muscle, the fascia graft allows normal vibration of the vocal fold mucosa to occur during phonation. Improvement of voice quality was seen in all series by multiple objective parameters of voice evaluation. However, the vocal results were poor in cases where the nerve trauma was severe, such as UVFP after chest surgery. ILAF is most suitable for correction of mild to moderate glottic gaps related to less severe nerve damage. Our results indicate that autologous fascia is a feasible and safe new injection material with good and stable vocal results. It offers a practical solution for surgeons who treat this complex issue.

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Modifications of surface materials and their effects on cleanability have important impacts in many fields of activity. In this study the primary aim was to develop radiochemical methods suitable for evaluating cleanability in material research for different environments. Another aim was to investigate the effects of surface modifications on cleanabilitity and surface properties of plastics, ceramics, concrete materials and also their coatings in conditions simulating their typical environments. Several new 51Cr and 14C labelled soils were developed for testing situations. The new radiochemical methods developed were suitable for examining different surface materials and different soil types, providing quantitative information about the amount of soil on surfaces. They also take into account soil soaked into surfaces. The supporting methods colorimetric determination and ATP bioluminescence provided semi-quantitative results. The results from the radiochemical and supporting methods partly correlated with each other. From a material research point of view numerous new materials were evaluated. These included both laboratory-made model materials and commercial products. Increasing the amount of plasticizer decreased the cleanability of poly(vinyl chloride) (PVC) materials. Microstructured surfaces of plastics improved the cleanability of PVC from particle soils, whereas for oil soil microstructuring reduced the cleanability. In the case of glazed ceramic materials, coatings affected the cleanability. The roughness of surfaces correlated with cleanability from particle soils and the cleanability from oil soil correlated with the contact angles. Organic particle soil was removed more efficiently from TiO2-coated ceramic surfaces after UV-radiation than without UV treatment, whereas no effect was observed on the cleanability of oil soil. Coatings improved the cleanability of concrete flooring materials intended for use in animal houses.

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Revolution at home! Visual Changes in Everyday Life in Finland in the Late 1960s and Early 1970s The purpose of my research was to investigate the visual changes in private homes in Finland during the 1960s and 1970s. The 1960s is often described as a turning point in Finnish life, a time when the society's previous agricultural orientation began to give way first to an industrial orientation and then, by the end of the 1970s, to a service orientation. My title refers to three elements in the transition period: the question of daily life; the timeframe; and the visual changes observable in private homes, which in retrospect signalled a kind of revolution in the social orientation. Those changes appeared not only in colours and designs but also in the forms and materials of household objects. My premise is that analysing interiors from a historical perspective can reveal valuable information about Finnish society and social attitudes, information that might easily escape attention otherwise. I have used the time-honoured method of collecting narratives. As far back as Aristotle, formulating narratives has been a means of gaining knowledge. By collecting and classifying narratives about the 1960s and 1970s, it is possible to gain new insight into these important decades. The archetypal 1960s narrative, involving student demonstrations and young people's efforts to improve society, is well known. Less well known is the narrative that relates the changes going on in daily life. Substantially the study focuses mainly on fabrics, porcelain ware and the use of plastics. Marimekko's style is especially important when following innovations in the 1950s, 1960s and 1970s. Porcelain production at the Arabia factory was another element that had a great influence on the look of Finnish homes and kitchens; and a further widespread phenomenon of the late 1960s and early 1970s was the use of plastics in many different forms. Further evidence was sought in Anttila department store mail catalogues, which displayed products that were marketed on a large scale, as well as in magazines such as Avotakka. The terminal point of the visual evolution is the real homes, as seen in the questionnaire "Homemade". I have used the 800 pages of the oral history text that respondents of the Finnish Literature Society have written about their first home in the 1960s. I also used archival material on actual homes in Helsinki from the archives of the Helsinki City Museum. The basic story is the elite narrative, which was produced by students in the 1960s. My main narrative from the same time is visual change in everyday life in the late 1960s and early 1970s. I have classified the main narrative of visual change into four subcategories: the narrative of national ideas, the narrative of a better standard of living, the narrative of objects in the culture of everyday life and the narrative of changing colour and form.