RESUMO
Rheology is proposed as a tool to explore plasticized poly(vinyl chloride) (PVC) formulations to be used in the fused filament fabrication (FFF) 3D printing process and so manufactures flexible and ductile objects by this technique. The viscoelastic origin of success/failure in FFF of these materials is investigated. The analysis of buckling of the filament is based on the ratio between compression modulus and viscosity, but for a correct approach the viscosity should be obtained under the conditions established in the nozzle. As demonstrated by small amplitude oscillatory shear (SAOS) measurements, PVC formulations have a crystallites network that provokes clogging in the nozzle. This network restricts printing conditions, because only vanishes at high temperatures, at which thermal degradation is triggered. It is observed that the analysis of the relaxation modulus G(t) is more performing than the Gâ³/G' ratio to get conclusions on the quality of layers welding. Models printed according to the established conditions show an excellent appearance and flexibility, marking a milestone in the route to obtain flexible objects by FFF.
RESUMO
INTRODUCTION: Stroke patients have a high risk of presenting complications, the appearance of which can condition the prognosis of the stroke. We studied the frequency and impact of the onset of several different complications on the early and mid-term prognosis of these patients. PATIENTS AND METHODS: We conducted an observation-based study of the patients admitted to a stroke unit. The complications that occurred while hospitalised were recorded, a distinction being drawn between neurological and medical complications. The study examined their influence, according to the subtype of stroke, on intra-hospital mortality and that at 90 days, as well as on the functional situation at 90 days, by analysing the clinical factors that are predictive for the appearance of complications. RESULTS: The sample consisted of 847 patients. Altogether, 29.5% of the patients presented complications, which were more frequent in haemorrhagic stroke (50.5% versus 26.6%; p < 0.0001). The most usual complications were of a neurological nature (21%). For both subtypes, the presence of complications was associated with a higher rate of mortality both in hospital (2.1% versus 12.6%; p < 0.0001) and at 90 days (5.7% versus 29.6%; p < 0.0001), and a lower probability of independence at 90 days (72.9% versus 30.4%; p < 0.0001). The severity of the stroke on admission revealed itself as the most powerful predictor of the onset of any type of complication. CONCLUSIONS: The appearance of complications during the acute phase of the stroke has an adverse influence on mortality and on the functional prognosis. The identification of predictive factors could reduce the impact upon the progress of acute stroke patients.
TITLE: Impacto de las complicaciones neurologicas y medicas sobre la mortalidad y situacion funcional de pacientes con ictus agudo.Introduccion. Los pacientes con ictus presentan un elevado riesgo de presentar complicaciones. Su aparicion puede condicionar el pronostico del ictus. Estudiamos la frecuencia y el impacto de la aparicion de diversas complicaciones en el pronostico precoz y a medio plazo en estos pacientes. Pacientes y metodos. Estudio observacional de los pacientes ingresados en una unidad de ictus. Se registraron las complicaciones durante su estancia, distinguiendose entre complicaciones neurologicas y medicas. Se estudio la influencia de estas segun subtipo de ictus en la mortalidad intrahospitalaria y a los 90 dias, y en la situacion funcional a los 90 dias, analizandose los factores clinicos predictores para la aparicion de complicaciones. Resultados. Muestra de 847 pacientes. Un 29,5% de los pacientes presento complicaciones, que fueron mas frecuentes en el ictus hemorragico (50,5% frente a 26,6%; p < 0,0001). Las complicaciones mas habituales fueron las neurologicas (21%). Para ambos subtipos, la presencia de complicaciones se asocio a mayor mortalidad intrahospitalaria (2,1% frente a 12,6%; p < 0,0001) y a 90 dias (5,7% frente a 29,6%; p < 0,0001), y menor probabilidad de independencia a 90 dias (72,9% frente a 30,4%; p < 0,0001). La gravedad del ictus al ingreso se mostro como el predictor mas potente en la aparicion de cualquier tipo de complicacion. Conclusiones. La aparicion de complicaciones durante la fase aguda del ictus influye de forma adversa en la mortalidad y en el pronostico funcional. La identificacion de factores predictores podria disminuir el impacto sobre la evolucion del paciente con un ictus agudo.
