Yield and Selectivity Improvement in the Synthesis of Carbonated Linseed Oil by Catalytic Conversion of Carbon Dioxide.

Carbonation of epoxidized linseed oil (CELO) containing five-membered cyclic carbonate (CC5) groups has been optimized to 95% by reacting epoxidized linseed oil (ELO) with carbon dioxide (CO2) and tetrabutylammonium bromide (TBAB) as catalysts. The effect of reaction variables (temperature, CO2 pressure, and catalyst concentration) on the reaction parameters (conversion, carbonation and selectivity) in an autoclave system was investigated. The reactions were monitored, and the products were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), carbon-13 nuclear magnetic resonance (13C-NMR) and proton nuclear magnetic resonance (1H-NMR) spectroscopies. The results showed that when carrying out the reaction at high temperature (from 90 °C to 120 °C) and CO2 pressure (60-120 psi), the reaction's conversion improves; however, the selectivity of the reaction decreases due to the promotion of side reactions. Regarding the catalyst, increasing the TBAB concentration from 2.0 to 5.0 w/w% favors selectivity. The presence of a secondary mechanism is based on the formation of a carboxylate ion, which was formed due to the interaction of CO2 with the catalyst and was demonstrated through 13C-NMR and FT-IR. The combination of these factors makes it possible to obtain the largest conversion (96%), carbonation (95%), and selectivity (99%) values reported until now, which are obtained at low temperature (90 °C), low pressure (60 psi) and high catalyst concentration (5.0% TBAB).

Intra- and extradural anterior clinoidectomy: anatomy review and surgical technique step by step.

PURPOSE: The complex relations of the paraclinoid area make the surgical management of the pathology of this region a challenge. The anterior clinoid process (ACP) is an anatomical landmark that hinders the visualization and manipulation of the surrounding neurovascular structures, hence in certain surgical interventions might be necessary to remove it. We reviewed the anatomical relationships that involve the paraclinoid area and detailed the step-by-step techniques of intra and extradural clinoidectomy in cadaveric specimens. MATERIALS AND METHODS: A literature review was done describing the most relevant anatomic relationships regarding the anterior clinoid process. Extradural and intradural clinoidectomy techniques were performed in six dry bone heads and in ten previously injected cadaverous specimens with colored latex (Sanan et al. in Neurosurgery 45:1267-1274, 1999) and each step of the procedure was recorded using photographic material. Finally, an analysis of the anatomical exposure achieved in each of the techniques used was performed. RESULTS: The main advantage of the intradural clinoidectomy technique is the direct visualization of the neurovascular structures adjacent to the ACP when drilling, at the same time, opening the Sylvian fissure will allow the direct visualization of the ACP variants. The main advantage offered by the extradural technique is that the dura protects adjacent eloquent structures while drilling. Among the disadvantages, it is noted that the same dura that would protect the underlying structures also prevents the direct visualization of these neurovascular structures adjacent to the ACP. CONCLUSION: We reviewed the anatomy of the paraclinoid area and made a step-by-step description of the technique of the anterior clinoidectomy in its intra- and extradural variants in cadaveric preparations for a better understanding.

A kinetic comparison between E2P and the E2P-like state induced by a beryllium fluoride complex in the Na,K-ATPase. Interactions with Rb.

Metal-fluoride complexes have been used to induce E2P-like states with the aim of studying the events that occur during E2P hydrolysis in P-type ATPases. In the present work, we compared the E2P-like state induced by a beryllium fluoride complex (BeFx) with the actual E2P state formed through backdoor phosphorylation of the Na,K-ATPase. Formation of E2P and E2P-like states were investigated employing the styryl dye RH421. We found that BeFx is the only fluorinated phosphate analog that, like Pi, increases the RH421 fluorescence. The observed rate constant, kobs, for the formation of E2P decreases with [Pi] whereas that of E2BeFx increases with [BeFx]. This might wrongly be taken as evidence of a mechanism where the binding of BeFx induces a conformational transition. Here, we rather propose that, like for Pi, binding of BeFx follows a conformational-selection mechanism, i.e. it binds to the E2 conformer forming a complex that is much more stable than E2P, as seen from its impaired capacity to return to E1 upon addition of Na+. Although E2P and E2BeFx are able to form states with 2 occluded Rb+, both enzyme complexes differ in that the affinity for the binding and occlusion of the second Rb+ is much lower in E2BeFx than in E2P. The higher rates of Rb+ occlusion and deocclusion observed for E2BeFx, as compared to those observed for other E2P-like transition and product states suggest a more open access to the cation transport sites, supporting the idea that E2BeFx mimics the E2P ground state.

Exploring the Impact of Early Decisions in Variable Ordering for Constraint Satisfaction Problems.

When solving constraint satisfaction problems (CSPs), it is a common practice to rely on heuristics to decide which variable should be instantiated at each stage of the search. But, this ordering influences the search cost. Even so, and to the best of our knowledge, no earlier work has dealt with how first variable orderings affect the overall cost. In this paper, we explore the cost of finding high-quality orderings of variables within constraint satisfaction problems. We also study differences among the orderings produced by some commonly used heuristics and the way bad first decisions affect the search cost. One of the most important findings of this work confirms the paramount importance of first decisions. Another one is the evidence that many of the existing variable ordering heuristics fail to appropriately select the first variable to instantiate. Another one is the evidence that many of the existing variable ordering heuristics fail to appropriately select the first variable to instantiate. We propose a simple method to improve early decisions of heuristics. By using it, performance of heuristics increases.

Fontan-Associated Liver Disease: A Review.

Fontan-associated liver disease is a hepatic disorder arising from hemodynamic changes and systemic venous congestion following Fontan surgery. The histological changes produced in the liver are similar but not equivalent to those seen in other forms of cardiac liver disease. While the natural history of this form of liver disease is not well established, over time many Fontan patients develop portal hypertension-related complications such as ascites, variceal hemorrhage or encephalopathy. Fontan survivors also show an increased risk of hepatocellular carcinoma. Early diagnosis of advanced liver disease is mandatory for the prevention and treatment of complications such as hepatocellular carcinoma, esophageal varices and malnutrition. This review updates current knowledge of the pathophysiology and management of Fontan-associated liver disease including new diagnostic methods and treatments.

Identification of Tequila with an Array of ZnO Thin Films: A Simple and Cost-Effective Method.

An array of ZnO thin film sensors was obtained by thermal oxidation of physical vapor deposited thin Zn films. Different conditions of the thermal treatment (duration and temperature) were applied in view of obtaining ZnO sensors with different gas sensing properties. Films having undergone a long thermal treatment exhibited high responses to low ethanol concentrations, while short thermal treatments generally led to sensors with high ethanol sensitivity. The sensor array was used to distinguish among Tequilas and Agave liquor. Linear discriminant analysis and the multilayer perceptron neural network reached 100% and 86.3% success rates in the discrimination between real Tequila and Agave liquor and in the identification of Tequila brands, respectively. These results are promising for the development of an inexpensive tool offering low complexity and cost of analysis for detecting fraud in spirits.

Influencia del tiempo de visita, grado de dependencia y presencia del cuidador, en la satisfacción de los usuarios del programa de atención domiciliaria (PADOMI) - Hospital II EsSalud Huánuco, 2015 / Influence of visiting time, degree of dependence and presence of the caregiver, in the satisfaction of the users of the home care program (PADOMI) - Hospital II EsSalud Huánuco, 2015

Los objetivos de la presente tesis son: Determinar la influencia del tiempo de visita del personal de salud, el grado de dependencia y la presencia del cuidador en la satisfacción de los usuarios del Programa de Atención Domiciliaria (PADOMI) del Hospital II EsSalud Huánuco. Materiales y métodos: El diseño fue descriptivo de corte transversal, la muestra estuvo constituida por 204 pacientes de los 589 registrados hasta noviembre del 2015, se empleó encuestas para recolectar los datos; para buscar asociación entre las variables independientes y la dependiente se utilizó ANOVA, Tau de Kendall y Chi2 para lo cual se empleó SPSS.V23. Resultados: Los resultados corresponden a 204 pacientes usuarios del Programa de Atención Domiciliaria (PADOMI), de los cuales 128 (62,7%) eran mujeres, con una con una edad promedio de 79,9 años (30 a 100 años). En cuanto a las características epidemiológicas de los pacientes de PADOMI se distribuyeron en 9 zonas la ciudad de Huánuco (A, B, C, D, E, F, G, I y J); siendo las de mayor distribución las zonas D (22,1%) y E (23,5%) correspondientes al casco urbano de la ciudad de Huánuco, en quienes el nivel de estudios: primaria completa (17,6%) y secundaria incompleta (12,3%) fueron los más frecuentes. Así mismo la religión que profesan en mayor proporción fue la Católica (82%). En cuanto al número de las comorbilidades, presentaron una media de 4,8 (DS+1,5), siendo las más frecuentes: hipertensión arterial (12,64%), gastritis (5,47%), osteoporosis (4,75%), insomnio (4,54%), diabetes mellitus tipo 2 (4,02%). Mientras que los pacientes de PADOMI presentaron un grado de dependencia total 20 (9,8%), severa 41 (20,1%), moderada 100 (49%), escasa 20 (9,8%) e independencia total 23 (11,3%) en el total de encuestados. Además encontrándose hacinamiento en 8 (3,9%) de los encuestados con una media de personas en la casa de 4,89 (DS+1,5) y una media de habitaciones en la casa de 3,86 (DS+2,08). Estando el paciente en compañía del cuidador principal (94,1%), siendo este un familiar (80,9%) y en algunos casos no contaba con persona responsable (5,9%) para su cuidado. En cuanto a las características epidemiológicas del cuidador principal, presentaron una edad media de 48,98 años (15 a 86 años), de los cuales 146 (71,6%) eran mujeres, siendo el o la esposo(a) (17,2%) los cuidadores principales, quienes tenían estudios superiores universitarios completos (32,4%), teniendo poco (27%) o regular (50%) conocimiento o experiencia en el cuidado de pacientes, que fue adquirido por la experiencia (74,5%), universidad o instituto (11,8%) y capacitado por PADOMI (7,8%); recibiendo una remuneración (15,7%) por el tiempo dedicado al cuidado del paciente, que presento una media de 17,42 horas durante el día. Además, se encontró que el número de visitas realizadas por el médico de PADOMI tuvo una media de 1,39 veces (DS+0,75) en el último mes, con una media de 17,87 minutos (DS+7,89) de duración cada visita. Hallándose una satisfacción alta en 134 (65,7%), media en 65 (31,9) y baja 5 (2,5%) en relación a la atención brindada por el médico de PADOMI. Mientras que en el análisis bivariado se observó que el nivel de satisfacción fueron más altos en el género femenino, con resultado no significativo (x2=0,678; p=0,713). En cuanto al nivel de satisfacción y la edad los resultados fueron no significativos (x2=0,686; p=0,71). Así mismo, el nivel de satisfacción y la presencia del cuidador los resultados fueron no significativos (x2=1,787; p=0,41) pero en el grupo de pacientes en cuyas casas tenían de 1 a 3 habitaciones el resultado fue significativo (x2=8,44; p=0,02). Mientras que el nivel de satisfacción y el tiempo de visita dedicado a los pacientes de PADOMI por parte del médico, los resultados fueron no significativos (x2=2,621; p=0,27), asimismo se observó dentro de este grupo resultados significativos en aquellos que eran hombres (x2=41,17; p=0,00), además en los pacientes que presentaron de 4 a 6 comorbilidades (x2=22,54; p=0,00), también en los pacientes que se encontraron hacinados (x2=8,00; p=0,02), en cuyas casas contaban de 4 a 6 habitaciones (x2=25,12; p=0,00), habitando en ella de 4 a 6 personas (x2=29,63; p=0,27), donde era el familiar el cuidador principal (x2=17,16; p=0,03), siendo este/a el/la esposo/a (x2=37,06; p=0,00), observándose significancia en la religión del cuidador que fue la católica (x2=16,41; p=0,04), refiriendo el cuidador tener mucho conocimiento o experiencia en atención de pacientes (x2=33,22; p=0,00), afirmando que fue adquirido en la universidad o instituto (x2=12,67; p=0,05). En relación al nivel de satisfacción y el grado de dependencia de los pacientes de PADOMI, los resultados fueron no significativos (x2=8,55; p=0,38). Se relacionó el nivel de satisfacción con el número de comorbilidades y se observó que los resultados fueron no significativos (x2=3,75; p=0,15). Así mismo se relacionó el nivel de satisfacción con el hacinamiento y se observó que los resultados fueron no significativos (x2=1,79; p=0,41). También se relacionó el nivel de satisfacción con el número de visitas por parte del médico a los pacientes de PADOMI y se observó que los resultados fueron no significativos (x2=0,28; p=0,87). Conclusión: Se concluye que la satisfacción no es influenciada por el tiempo de visita del personal médico a los usuarios del Programa de Atención Domiciliaria (PADOMI) del Hospital II EsSalud Huánuco en el 2015, sin embargo se encontró que el nivel de satisfacción es influenciado por el tiempo de visita dedicado por parte del médico a los pacientes de PADOMI, que fueron hombres, que presentaron de 4 a 6 comorbilidades, que se encontraban hacinados en sus viviendas, que contaban de 4 a 6 habitaciones, que cuyas viviendas eran habitadas por 4 a 6 personas, que contaban con un cuidador principal el cual era un familiar, quien tenía el grado de parentesco de esposo/a, cuya religión fue la católica, que refiere tener mucho conocimiento o experiencia en atención de pacientes, cuyo conocimiento fue adquirido en la universidad o instituto. Asimismo se concluye que la presencia cuidador no es influenciada en la Satisfacción de los usuarios del Programa de Atención Domiciliaria (PADOMI), sin embargo se determinó que el nivel de satisfacción fue influenciado en aquellos pacientes que contaban con un cuidador principal en cuyas viviendas contaban de 1 a 3 habitaciones.

Experimental Matching of Instances to Heuristics for Constraint Satisfaction Problems.

Constraint satisfaction problems are of special interest for the artificial intelligence and operations research community due to their many applications. Although heuristics involved in solving these problems have largely been studied in the past, little is known about the relation between instances and the respective performance of the heuristics used to solve them. This paper focuses on both the exploration of the instance space to identify relations between instances and good performing heuristics and how to use such relations to improve the search. Firstly, the document describes a methodology to explore the instance space of constraint satisfaction problems and evaluate the corresponding performance of six variable ordering heuristics for such instances in order to find regions on the instance space where some heuristics outperform the others. Analyzing such regions favors the understanding of how these heuristics work and contribute to their improvement. Secondly, we use the information gathered from the first stage to predict the most suitable heuristic to use according to the features of the instance currently being solved. This approach proved to be competitive when compared against the heuristics applied in isolation on both randomly generated and structured instances of constraint satisfaction problems.

Trasplante de microbiota fecal: indicaciones, metodología y perspectivas futuras / Faecal microbiota transplantation: indications, methodology and future prospects

La microbiota intestinal se define como el conjunto de microorganismos que habitan de forma natural en el tubo digestivo. Bacterias, hongos y virus se incluyen dentro de este ente fisiológico que va mucho más allá de ser un mero espectador pasivo de la mucosa intestinal. La microbiota interviene de forma activa en la homeostasis y su desregulación se ha relacionado con múltiples enfermedades de naturaleza infecciosa, metabólica y autoinmunitaria. El trasplante de microbiota fecal (TMF) consiste en la introducción de una solución de materia fecal debidamente procesada procedente de un donante sano en el tracto gastrointestinal de otro individuo con el fin de manipular las características de la microbiota del receptor. Aunque pueda parecer algo novedoso, los primeros casos se remontan a la época de la China Imperial; no obstante, no ha sido hasta los últimos 20 años cuando el interés y la actividad investigadora en este campo se han multiplicado de forma exponencial. Fruto de este trabajo el TMF constituye hoy en día una herramienta eficaz y validada en casos refractarios de diarrea por C. Difficile. Aunque la evidencia científica es menor, ya existen ensayos clínicos que evalúan su beneficio en la enfermedad inflamatoria intestinal y en el síndrome metabólico. Lo atractivo de su mecanismo fisiopatológico, la sencillez del procedimiento y su bajo coste lo sitúan como un tratamiento prometedor en múltiples enfermedades extradigestivas. El objetivo de esta revisión es resumir de una forma concisa, rigurosa y actualizada las indicaciones, metodología y seguridad del TMF.

The intestinal microbiota is defined as the set of organisms that live in the digestive tract. Bacteria, fungi and viruses are included in a physiological entity that goes far beyond being a passive spectator of the intestinal mucosa. The microbiota is actively involved in homeostasis and its imbalance has been linked to multiple infectious, metabolic and autoimmune diseases. Fecal microbiota transplantation (FMT) consists in the introduction of a solution made with processed stool from a healthy donor into the gastrointestinal tract of another individual in order to manipulate the characteristics of the receiver microbiota. Although it may seem new, the first cases date back to the days of Imperial China; however, it was not until the past 20 years when the interest and research in this field have grown exponentially. Nowadays, TMF is an effective and validated treatment in refractory cases of C.difficile diarrhea. Although the scientific evidence is less, there are clinical trials evaluating its benefit in inflammatory bowel disease and metabolic syndrome. The appeal of its pathophysiological mechanism, the simplicity of the procedure and its low cost place FMT as a promising treatment for multiple extraintestinal diseases. The objective of this review is to summarize in a concise, thorough and updated form its indications, methodology and safety.

Hepatitis aguda como única manifestación de sífilis en un paciente inmunocompetente.

Syphilis is a chronic systemic infection mainly transmitted through sexual contact that shows a great variety of clinical manifestations. Liver involvement is an unusual complication mainly reported in HIV patients. In this case report we present a case of a 42-year-old immunocompent man with acute cholestatic hepatitis who was finally diagnosed of luetic hepatitis. Liver disease was the only manifestation of syphilis infection difficulty it's diagnostic. We emphasize the importance of including syphilis in the differential diagnosis of abnormal liver function tests in patients at risk of sexually transmitted diseases due to its resolution with appropriate antibiotic treatment.

Normativas de diagnóstico y tratamiento del déficit de alfa-1 antitripsina / Guidelines on Diagnosis and Treatment of Alpha-1 Antitrypsin Deficiency

El déficit de alfa-1 antitripsina (AAT) es una condición hereditaria rara y raramente diagnosticada en todo el mundo, incluida Argentina. El infradiagnóstico es fundamentalmente debido a que muchos médicos desconocen su existencia, diagnóstico y tratamiento. Por ello, la Asociación Argentina de Medicina Respiratoria encomendó a un grupo de expertos la elaboración de la presente normativa. La AAT es una glicoproteína secretada por el hígado, muy abundante en sangre, tejidos y fluidos corporales, cuya función principal consiste en inhibir la elastasa del neutrófilo y otras serin proteasas, confiriendo al suero humano más del 90% de su capacidad antiproteasa. El déficit de AAT deriva de mutaciones del gen de la SERPINA1, y se manifiesta clínicamente por enfisema pulmonar, cirrosis hepática y, con menor frecuencia, por paniculitis, vasculitis sistémicas y posiblemente otras enfermedades. El déficit grave de AAT afecta mayoritariamente a individuos de raza caucasiana y tiene su máxima prevalencia (1:2.000-1:5.000 individuos) en el norte, oeste y centro de Europa. En EEUU y Canadá, la prevalencia es de 1: 5.000-10.000, y es 5 veces menor en países latinoamericanos, incluida Argentina, donde se estima que puede haber unos 18.000 individuos con genotipos deficientes graves SZ y ZZ, la inmensa mayoría sin diagnosticar. Sospechar la enfermedad resulta clave para medir la concentración sérica de AAT y completar el diagnóstico con la determinación del fenotipo o genotipo ante concentraciones bajas. La detección de casos permite la puesta en práctica del consejo genético, el chequeo de familiares consanguíneos y, en casos seleccionados, la aplicación de terapia sustitutiva.

The alpha-1 antitrypsin (AAT) deficiency is a rare hereditary condition which is rarely diagnosed in the world, including Argentina. Underdiagnosis is mainly due to lack of knowledge of its diagnosis and treatment by many physicians. For this reason, the Argentine Association of Respiratory Medicine convened a group of experts to develop the present guidelines. AAT is a glycoprotein secreted by the liver; it reaches high levels in blood, body tissues and fluids. Its main function is to inhibit the neutrophil elastase and other serum proteases providing 90% of human serine antiprotease activity. The AAT deficiency is produced by mutations of the SERPINA1 gene. Its clinical manifestations are pulmonary emphysema, liver cirrhosis, and less often panniculitis, systemic vasculitis and possibly other conditions. The severe AAT deficiency affects mainly Caucasian individuals. The highest prevalence, ranging from 1 in 2000 to 1 in 5000 population is observed in northern, western and central Europe. In the USA and Canada, the prevalence varies from 1 in 5000 to 1 in 10000 population. It is 5 times less frequent in Latin American countries. It is estimated that in Argentina there may be 18000 cases with severe deficiency of SZ y ZZ genotypes, most of them undiagnosed. It is crucial to suspect the disease in order to measure the serum AAT concentration, and, if the concentrations are low, to confirm the diagnosis with the phenotype or genotype determinations. Case detection allows genetic advice, control of blood-related relatives and in selected cases, replacement therapy.

Normativas de diagnóstico y tratamiento del déficit de alfa-1 antitripsina

El déficit de alfa-1 antitripsina (AAT) es una condición hereditaria rara y raramente diagnosticada en todo el mundo, incluida Argentina. El infradiagnóstico es fundamentalmente debido a que muchos médicos desconocen su existencia, diagnóstico y tratamiento. Por ello, la Asociación Argentina de Medicina Respiratoria encomendó a un grupo de expertos la elaboración de la presente normativa. La AAT es una glicoproteína secretada por el hígado, muy abundante en sangre, tejidos y fluidos corporales, cuya función principal consiste en inhibir la elastasa del neutrófilo y otras serin proteasas, confiriendo al suero humano más del 90% de su capacidad antiproteasa. El déficit de AAT deriva de mutaciones del gen de la SERPINA1, y se manifiesta clínicamente por enfisema pulmonar, cirrosis hepática y, con menor frecuencia, por paniculitis, vasculitis sistémicas y posiblemente otras enfermedades. El déficit grave de AAT afecta mayoritariamente a individuos de raza caucasiana y tiene su máxima prevalencia (1:2.000-1:5.000 individuos) en el norte, oeste y centro de Europa. En EEUU y Canadá, la prevalencia es de 1: 5.000-10.000, y es 5 veces menor en países latinoamericanos, incluida Argentina, donde se estima que puede haber unos 18.000 individuos con genotipos deficientes graves SZ y ZZ, la inmensa mayoría sin diagnosticar. Sospechar la enfermedad resulta clave para medir la concentración sérica de AAT y completar el diagnóstico con la determinación del fenotipo o genotipo ante concentraciones bajas. La detección de casos permite la puesta en práctica del consejo genético, el chequeo de familiares consanguíneos y, en casos seleccionados, la aplicación de terapia sustitutiva.(AU)

The alpha-1 antitrypsin (AAT) deficiency is a rare hereditary condition which is rarely diagnosed in the world, including Argentina. Underdiagnosis is mainly due to lack of knowledge of its diagnosis and treatment by many physicians. For this reason, the Argentine Association of Respiratory Medicine convened a group of experts to develop the present guidelines. AAT is a glycoprotein secreted by the liver; it reaches high levels in blood, body tissues and fluids. Its main function is to inhibit the neutrophil elastase and other serum proteases providing 90% of human serine antiprotease activity. The AAT deficiency is produced by mutations of the SERPINA1 gene. Its clinical manifestations are pulmonary emphysema, liver cirrhosis, and less often panniculitis, systemic vasculitis and possibly other conditions. The severe AAT deficiency affects mainly Caucasian individuals. The highest prevalence, ranging from 1 in 2000 to 1 in 5000 population is observed in northern, western and central Europe. In the USA and Canada, the prevalence varies from 1 in 5000 to 1 in 10000 population. It is 5 times less frequent in Latin American countries. It is estimated that in Argentina there may be 18000 cases with severe deficiency of SZ y ZZ genotypes, most of them undiagnosed. It is crucial to suspect the disease in order to measure the serum AAT concentration, and, if the concentrations are low, to confirm the diagnosis with the phenotype or genotype determinations. Case detection allows genetic advice, control of blood-related relatives and in selected cases, replacement therapy.(AU)

Tribological properties of polymer nanohybrids containing gold nanoparticles obtained by laser ablation.

We have studied polystyrene (PS)+Au particles nanohybrids. Approximately spherical gold nanoparticles with the average diameter of 15 nm were obtained by laser ablation in a liquid environment. Thus any chemical residue on the particles was eliminated. Focused ion beam (FIB) milling plus scanning electron microscopy (SEM) observation show that Au particles are fairly well dispersed inside the polymer matrix, better than when PS is simply dissolved in a nanoparticle solution. The Au particles concentration as low as 0.15 wt% results in dramatic changes in tribological properties, namely dynamic friction and pin-on-disk wear. Both wear and dynamic friction results are explained in terms of high brittleness of PS, abrasion of Au particles against a ceramic indenter, and also effects of density of filler particles in the matrix on tribological properties. Effects of varying normal load on friction are small.

Displasia das valvas atrioventriculares em pacientes com diagnóstico de Síndrome de Down e sem cardiopatia congênita / Atrioventricular valve dysplasia in patients with Down Syndrome without congenital heart disease

Introdução: É bastante conhecido que a cardiopatia congênita está relacionada à síndrome de Down. Entretanto, existem raros relatos de casos de displasia valvar em crianças portadoras de síndrome de Down, sem cardiopatia associada. Objetivos: Verificar a presença e magnitude de alterações nas valvas atrioventriculares, em pacientes com diagnóstico de síndrome de Down, sem cardiopatia congênita associada. Método: Foi realizado um estudo transversal, com captação prospectiva de 162 pacientes, avaliados pela ecocardiografia, classificados em Grupo 1, portadores de Síndrome de Down (n = 81) e Grupo 2, crianças normais, do ponto de vista genético e cardiológico (n = 81). Resultados: A frequência de displasia das valvas tricúspide e mitral foi superior no grupo 01, quando comparado ao grupo 2 (55 versus 0, p<0,00001 e 20 versus 2, p < 0,0001, respectivamente). No grupo 1, 19 crianças apresentaram comprometimento simultâneo das valvas tricúspide e mitral. O comprometimento isolado da valva tricúspide ocorreu em 36 casos e da valva mitral ocorreu em apenas 01 caso (p < 0,01). Vinte e cinco crianças do Grupo 1 tinham ambas as valvas normais. Conclusão: Este estudo descreveu, pela primeira vez, a alta frequência de displasia nas válvulas tricúspide e mitral, em crianças e adolescentes com síndrome de Down, sem doença cardíaca congênita.

Introduction: It is well known that congenital heart disease is related to Down syndrome, however there are rare reports of valvular dysplasia in children with Down syndrome without associated congenital heart disease. Objectives: To determine the presence and magnitude of changes in atrioventricular valves in patients with Down’s syndrome without associated congenital heart diseases. Methods: We conducted a prospective cross-sectional study of 162 patients assessed by echocardiography, classifi edin Group 1, patients with Down syndrome (n = 81) and Group 2, genetically normal children without congenital heart disease. (n=81). Results: Th e frequency of dysplasia of tricuspid and mitral valves was higher in the group 1 compared to group 2 (55 vs 0, p <0.00001 and 20 versus 2, p <0.0001, respectively). In group 1, 19 children had simultaneous involvement of the tricuspid and mitral valves. Th e isolated involvement of the tricuspid valve occurred in 36 cases and isolated involvement of the mitral valve inonly one case (p <0.01). Twenty-fi ve children in a group containing both normal valves. Conclusion: To our knowledge, this study described for the fi rst time the high frequency of dysplasia in the tricuspid and mitral valves in children with Down’s syndromewithout congenital heart disease.

Tree-in-bud pattern at thin-section CT of the lungs: radiologic-pathologic overview.

The tree-in-bud pattern is commonly seen at thin-section computed tomography (CT) of the lungs. It consists of small centrilobular nodules of soft-tissue attenuation connected to multiple branching linear structures of similar caliber that originate from a single stalk. Originally reported in cases of endobronchial spread of Mycobacterium tuberculosis, this pattern is now recognized as a CT manifestation of many diverse entities. These entities include peripheral airway diseases such as infection (bacterial, fungal, viral, or parasitic), congenital disorders, idiopathic disorders (obliterative bronchiolitis, panbronchiolitis), aspiration or inhalation of foreign substances, immunologic disorders, and connective tissue disorders and peripheral pulmonary vascular diseases such as neoplastic pulmonary emboli. Knowledge of the many causes of this pattern can be useful in preventing diagnostic errors. In addition, although the causes of this pattern are frequently indistinguishable at radiologic evaluation, the presence of additional radiologic findings, along with the history and clinical presentation, can often be useful in suggesting the appropriate diagnosis.

Cirugía ambulatoria: experiencia en el hospital distrital "Dr. Miquel Malpica Jimenez". Guacara Estado Carabobo / Ambulatory surgery: experience in the district hospital \"Dr. Miguel Malpica Jimenez\". Guacara State Carabobo

La cirugía ambulatoria es actualmente una alternativa válida para combatir los altos costos de la medicina; en muchos centros de países desarrollados la cirugía ambulatoria presenta entre el 40 por ciento y el 50 por ciento de todas las intervenciones realizadas. En esta comunicación se prresenta la experiencia con este tipo de procedimiento en el Hospital Distrital "Dr. Miguel Malpica Jiménez" de la población de Guacara, Edo. Carabobo. Se estudiaron 170 pacientes desde junio de 1991 a junio de 1992, de los cuales 96 (56,47 por ciento ) fueron hombres y 74 (43,53 por ciento ) mujeres; el promedio de edad fue de 35 ñ 5 años, con un rango entre 12 y 70 años. Las patologías quirúrgicas más frecuentes fueron las hernias con 101 casos(64,11 por ciento ), seguidas de las lesiones de los tejidos blandos con 27 casos (15,88 por ciento ), y fibroadenomas de las mama 16 casos (7,05 por ciento ). El tiempo quirúrgico promedio fue de 35 ñ 10 minutos con un rango entre 20 y 90 minutos. El procedimiemto fue bien tolerado por los pacientes. No hubo complicaciones intraoperatorias y la postoperatorias fueron mínimas (4,7 por ciento ). Sólo se readmitieron 8 pacientes, 2 de ellos por presentar complicaciones inherentes a la cirugía y el resto por presentar problemas médicos distintos al acto quirúrgico. En nuestra serie no hubo mortalidad. A través del trabajo se demuestra que la cirugía ambulatoria es posible realizarla en hospitales urbanos tipo II o III con mínimo riesgo y grandes beneficios tanto para el paciente como para el hospital