Redesign of a Piston for a Diesel Combustion Engine to Use Biodiesel Blends.

Biofuels represent an energy option to mitigate polluting gases. However, technical problems must be solved, one of them is to improve the combustion process. In this study, the geometry of a piston head for a diesel engine was redesigned. The objective was to improve the combustion process and reduce polluting emissions using biodiesel blends as the fuel. The methodology used was the mechanical engineering design process. A commercial piston (base piston) was selected as a reference model to assess the piston head's redesign. Changes were applied to the profile of the piston head based on previous research and a new model was obtained. Both models were evaluated and analyzed using the finite element method, where the most relevant physical conditions were temperature and pressure. Numerical simulations in the base piston and the new piston redesign proposal presented similar behaviors and results. However, with the proposed piston, it was possible to reduce the effort and the material. The proposed piston profile presents adequate results and behaviors. In future, we suggest continuing conducting simulations and experimental tests to assess its performance.

Helicobacter pylori culture as a key tool for diagnosis in Colombia.

INTRODUCTION: The presence of H. pylori in the stomach is associated with gastric pathologies. However, its diagnosis through culture methods is challenging because of its complex nutritional requirements and microaerophilic conditions for optimal growth. The preferred method for rapid diagnosis of H. pylori is the Rapid Urease Test (RUT) from human biopsies, which relies on the high activity of the urease enzyme present in H. pylori. However, RUT cannot say much more information about H. pylori. This makes evident the need for bacterial culture to know essential information such as the strain type, the kind of infection present and the bacteria's antibiotic susceptibility. METHODOLOGY: Gastric biopsies from 347 patients were used for H. pylori isolation. We correlated the culture results with the RUT and histological grading used at Hospital Universitario Fundación SantaFe de Bogotá (HU-FSFB), Colombia. The concordance between techniques was determined by the Cohen's Kappa coefficient (K). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were also calculated. RESULTS: The culture standardization was successful, and it could be applied for diagnosis in the clinical practice. H. pylori was positive by culture in 88 (26.34%) patients. The concordance of RUT and culture was strong (K= 0.805), and between histology and culture was moderate (K= 0.763) as well as for the gold standard defined and culture (K= 0.80). CONCLUSIONS: We present evidence that RUT and histological methods will be better interpreted for diagnosis of H. pylori if combined with bacterial isolation in cholesterol enriched culture.

Diagnóstico final de pacientes con sospecha de accidente cerebrovascular descartado. Experiencia del Hospital de Chillán, chile / Final diagnosis of patients with suspect of ruled out stroke. experience of the Hospital of Chillán, Chile

INTRODUCCIÓN: El accidente cerebrovascular (ACV) es una lesión neurológica aguda con dos subtipos clásicos (isquémico y hemorrágico); siendo un importante problema de salud púbica en Chile. Existen patologías que imitan su presentación, sin embargo, una historia clínica y examen físico orientado permiten discriminar en un alto número de casos entre estas patologías evitando la derivación a especialista y solicitud de exámenes imagenológicos, disminuyendo así, los costos derivados en un gran número de pacientes. MATERIAL Y MÉTODO: Estudio transversal a partir de las fichas clínicas de pacientes ingresados con sospecha de ACV durante febrero y marzo del 2016 en Hospital Clínico Herminda Martín de Chillán para su confirmación diagnóstica por el Servicio de Neurología. RESULTADOS: Se obtuvieron 304 fichas clínicas con sospecha de ACV de las cuales un 26,9% no correspondieron a ACV. De estos, 45,9% eran patologías de especialidades no neurológicas siendo las más frecuentes las derivadas de Medicina Interna. DISCUSIÓN: El ACV es una entidad neurológica clásicamente descrita en base a la ubicación de la lesión vascular. Pese a que su presentación semiológica es conocida, existen muchas patologías que son clínicamente similares, o bien, las características singulares de los pacientes hacen que el patrón clínico sea confuso. Este fenómeno se refleja en una tasa de falsos ACV relativamente similar entre diferentes centros de salud. La tasa de error en diagnóstico de ACV en el estudio es de 26,9%, similar a otras experiencias. Pareciera ser que existe un número basal de falsos ACV, cuyo margen de error clínico, resulta difícil reducir aún con buenas escalas y protocolos estandarizados de atención.

INTRODUCTION: Stroke is an acute neurological lesion with two classic subtypes (ischemic and hemorrhagic), being an important public health problem in Chile. There are pathologies that mimic its presentation, however, a clinical history and oriented physical examination allow to discriminate in a high number of cases between these pathologies avoiding the referral to specialist and request of imaging examinations, thus reducing, the costs derived in a large number of patients. MATERIAL AND METHOD: Cross-sectional study from the clinical records of patients admitted with suspected stroke during February and March of 2016 at Herminda Martin Clinic Hospital from Chile for diagnostic confirmation by the Neurology Service. RESULTS: A total of 304 clinical files were obtained with suspected stroke, of which 26,9% did not correspond to stroke. Of these, 45,9% were pathologies of non-neurological specialties, the most frequent being those derived from internal medicine. DISCUSSION: Stroke is a neurological entity classically described based on the location of the vascular lesion. Although its semiologic presentation is known, there are many pathologies that are clinically similar, or the unique characteristics of the patients make the clinical pattern confusing. This phenomenon is reflected in a relatively similar false stroke rate among different health centers. The error rate in diagnosis of stroke of this study is 26,9%, similar to other experiences. It appears that there is a basal number of false stroke, whose clinical margin of error is difficult to reduce even with good scales and standardized care protocols.