Propiedades de los materiales compuestos reforzados con fibras de guadua: un estudio comparativo

A numerical model for predicting the effect of the modification of a fiber´s surface on the mechanical properties of biocomposite panels made with bamboo fibers and vegetable resin was elaborated. For the study, the three surface treatments methods were mercerization, plasma, and ozone treatment. To analyze the influence of each treatment on the surface of the fibers, a study of their morphology, chemical composition, and crystallinity was carried out using scanning electron microscopy, X-ray energy dispersion spectroscopy, and X-ray diffraction. A characterization of the physical properties of the fibers was carried out by determining the density and the absorption capacity. The influence of the treatment on the mechanical properties of the fibers was analyzed by determining their tensile strength. These results were used to determine the elastic properties of the plies that make up the biocomposite, applying the modified mixing rule for anisotropic materials. The numerical models were elaborated using a commercial finite element program, considering a linear analysis. The composite was conceived as a laminate made up of layers of fibers oriented in different directions. To validate the numerical results, panels were made using fibers treated according to established treatment methods and a vegetable resin. For the construction of the panels, a compression system at standard room temperature was used. The fibers were placed in six 1.13 mm-thick layers, reproducing the conditions established in the numerical model. The determination of the physical properties of the composite was based on the determination of the density, the absorption capacity, and the percentage of swelling. The determination of the mechanical properties focused on obtaining the maximum strength for tensile, compression, and static bending. The results show that it is possible to improve the mechanical performance of the composite when the surface of the fibers that act as reinforcement is modified. According to the results, panels made with fibers treated with plasma and with ozone exhibited better mechanical performance, showing a good correlation between the results of the numerical models and the values obtained experimentallySe elaboró un modelo numérico para predecir el efecto de la modificación de la superficie de una fibra sobre las propiedades mecánicas de los paneles de biocompuestos fabricados con fibras de bambú y resina vegetal. Para el estudio, los tres métodos de tratamiento superficial fueron la mercerización, el plasma y el tratamiento con ozono. Para analizar la influencia de cada tratamiento en la superficie de las fibras, se realizó un estudio de su morfología, composición química y cristalinidad mediante microscopía electrónica de barrido, espectroscopia de dispersión de energía de rayos X y difracción de rayos X. Se llevó a cabo una caracterización de las propiedades físicas de las fibras mediante la determinación de la densidad y la capacidad de absorción. La influencia del tratamiento en las propiedades mecánicas de las fibras se analizó determinando su resistencia a la tracción. Estos resultados se utilizaron para determinar las propiedades elásticas de las capas que componen el biocompuesto, aplicando la regla de la mezcla modificada para materiales anisótropos. Los modelos numéricos se elaboraron utilizando un programa comercial de elementos finitos, considerando un análisis lineal. El compuesto se concibió como un laminado formado por capas de fibras orientadas en diferentes direcciones. Para validar los resultados numéricos, se fabricaron paneles utilizando fibras tratadas según los métodos de tratamiento establecidos y una resina vegetal. Para la construcción de los paneles se utilizó un sistema de compresión a temperatura ambiente estándar. Las fibras se colocaron en seis capas de 1,13 mm de espesor, reproduciendo las condiciones establecidas en el modelo numérico. La determinación de las propiedades físicas del compuesto se basó en la determinación de la densidad, la capacidad de absorción y el porcentaje de hinchamiento. La determinación de las propiedades mecánicas se centró en la obtención de la resistencia máxima a tracción, compresión y flexión estática. Los resultados muestran que es posible mejorar las prestaciones mecánicas del compuesto cuando se modifica la superficie de las fibras que actúan como refuerzo. De acuerdo con los resultados, los paneles fabricados con fibras tratadas con plasma y con ozono presentaron mejores prestaciones mecánicas, mostrando una buena correlación entre los resultados de los modelos numéricos y los valores obtenidos experimentalmente

Higher Landau levels contribution to the energy of interacting electrons in a quantum dot

Properly regularized second-order degenerate perturbation theory is applied to compute the contribution of higher Landau levels to the low-energy spectrum of interacting electrons in a disk-shaped quantum dot. At ``filling factor'' near 1/2, this contribution proves to be larger than energy differences between states with different spin polarizations. After checking convergence of the method in small systems, we show results for a 12-electron quantum dot, a system which is hardly tractable by means of exact diagonalization techniques.Comment: 4 pages, 4 figure

Microsatellite variation in Spanish Alano dogs

We have studied a sample of 35 spanish alano dogs in order to estimate the level of genetic variability that can be detected by using microsatellites and the efficiency of these genetic markers as tools for parentage testing in this canine population. We have used 4 microsatellites previously described in the literature. All of them were polymorphic, with an average number of 5 alleles/ locus and an average gene diversity (H) of 0,70 ± 0,06, similar to the figures reported in others breeds. Two of the microsatellites showed disa-greement with Hardy-Weinberg proportions, due to a deficit of heterozygotes. We have found in one of the microsatellites alleles that could be breed specific, as they have not been detected in other spanish breeds. The combined exclusion probability detected is higher than 90 percent, suggesting the possibility of using efficiently microsatellites in parentage testing in the spanish alano population.En una muestra de 35 alanos españoles se investigó la utilidad de los microsatélites para detectar variabilidad genética y para el control de paternidad. Los 4 microsatélites utilizados, descritos ya en la bibliografía, resultaron polimórficos, con un número medio de 5 alelos/ locus y una heterocigosis media (H), de 0,70 ± 0,06, similar a la de otras razas caninas. Se ha detectado una desviación del equilibrio Hardy-Weinberg para dos microsatélites debida a un déficit de heterocigotos. En un microsatélite se han detectado alelos inexistentes en otras razas españolas, por lo que podrían ser específicos de raza. La probabilidad acumulada de exclusión de paternidad es superior al 90 p.100, por lo que podrían ser eficaces para estas pruebas en alanos

Use of antimicrobials in the medical service of theGeneral-Educational Hospital "Dr. Enrique Cabrera". 2016

Introduction: Since the conference about the rational use of drugs of the World Health Organization in 1985, this practice had been improving, especially antimicrobials, to prevent the increased of the resistance to these. Objective: To characterize the use of antimicrobials in the medical services of the General-Educational Hospital "Dr. Enrique Cabrera" in January 2016. Material and Methods: A retrospective and descriptive study of both sexes hospitalized 171 patients; older than 20 years old was performed. The medical records were reviewed to achieve the study variables and a database in Microsoft Excel was elaborated, that was analyzed, determining their absolute and relative frequencies. Results: 57.3% of patients received antimicrobial therapy, 52.1% were male, 38.7% hypertensive, 66.3% were 60 years and older, 77.5% received antimicrobials to treat infections, 82.8% of them were breathing low, 88.1% were treated with a combinations of 2 drugs and any microbiological testing of clinical suspicion was performed, in all, oralway was used, in 88.1% the intravenous via  was used and in none of the patients antimicrobial sequential therapy was performed, in 80.3 %  treatment period was 10 days, 50.6% received third generation cephalosporin and the most used was cefotaxime 97 (44.2%). Conclusions: The use of antimicrobials in hospitalized patients presented difficulties related to non-performing microbiological studies, the high use of intravenous and non-use of antimicrobial sequential therapy. Keywords: drugs, antimicrobials, prevalence, use, prescription, hospitals, therapeutics, infection, administration via, microbiological study.</p

Understanding seasonal weight loss tolerance in dairy goats: a transcriptomics approach

Research ArticleBackground: Seasonal weight loss (SWL) is a very important limitation to the production of ruminants in the Mediterranean and Tropical regions. In these areas, long dry seasons lead to poor pastures with low nutritional value. During the dry season, ruminants, particularly those raised in extensive production systems, lose around 30% of their body weight. Seasonal weight loss has important consequences on animal productive performance and health. In this study, RNA sequencing was used to characterize feed restriction effects in dairy goat of 2 breeds with different SWL tolerance: Majorera (tolerant) and Palmera (susceptible). Nine Majorera and ten Palmera goats were randomly distributed in a control and a restricted group: Majorera Control (adequately fed; MC; n = 4), Palmera Control (adequately fed; PC; n = 6), Majorera Restricted (feed restricted; ME; n = 5) and Palmera Restricted (feed restricted; PE; n = 4). On day 22 of the trial, mammary gland biopsies were collected for transcriptomics analysis. Results: From these samples, 24,260 unique transcripts were identified. From those, 82 transcripts were differentially expressed between MC and ME, 99 between PC and PE, twelve between both control groups and twenty-nine between both restricted groups. Conclusions: Feed restriction affected several biochemical pathways in both breeds such as: carbohydrate and lipid transport; intracellular trafficking, RNA processing and signal transduction. This research also highlights the importance or involvement of the genes in tolerance (ENPP1, S-LZ, MT2A and GPNB) and susceptibility (GPD1, CTPS1, ELOVL6 and NR4A1) to SWL with respectively higher expression in the Majorera restriced group and the Palmera restricted group in comparison to the control groups. In addition, results from the study may be extrapolated to other dairy ruminant speciesinfo:eu-repo/semantics/publishedVersio

Estimating the frequency of Asian cytochrome B haplotypes in standard European and local Spanish pig breeds

Mitochondrial DNA has been widely used to perform phylogenetic studies in different animal species. In pigs, genetic variability at the cytochrome B gene and the D-loop region has been used as a tool to dissect the genetic relationships between different breeds and populations. In this work, we analysed four SNP at the cytochrome B gene to infer the Asian (A1 and A2 haplotypes) or European (E1 and E2 haplotypes) origins of several European standard and local pig breeds. We found a mixture of Asian and European haplotypes in the Canarian Black pig (E1, A1 and A2), German Piétrain (E1, A1 and A2), Belgian Piétrain (E1, A1), Large White (E1 and A1) and Landrace (E1 and A1) breeds. In contrast, the Iberian (Guadyerbas, Ervideira, Caldeira, Campanario, Puebla and Torbiscal strains) and the Majorcan Black pig breeds only displayed the E1 haplotype. Our results show that the introgression of Chinese pig breeds affected most of the major European standard breeds, which harbour Asian haplotypes at diverse frequencies (15–56%). In contrast, isolated local Spanish breeds, such as the Iberian and Majorcan Black pig, only display European cytochrome B haplotypes, a feature that evidences that they were not crossed with other Chinese or European commercial populations. These findings illustrate how geographical confinement spared several local Spanish breeds from the extensive introgression event that took place during the 18th and 19th centuries in Europe

La resolución de problemas en el contexto de la programación: Un estudio diagnóstico en estudiantes de la carrera Licenciatura en Educación, especialidad Informática

En el presente trabajo se articula la fase teórica con el desarrollo y la aplicación de instrumentos, que permiten analizar los resultados de un estudio tipo diagnóstico sobre la habilidad resolver problemas, en la disciplina Lenguaje y Técnica de Programación (LTP) en los estudiantes de segundo año de la carrera de Informática de la Universidad de Ciencias Pedagógicas “Rafael María de Mendive” de Pinar del Rí

A genome-wide perspective about the diversity and demographic history of seven Spanish goat breeds

Altres ajuts: Félix Goyache is supported by Grant FICYT GRUPIN14-113. Valentin Balteanu is the recipient of a grant awarded under the frame of the European Social Fund, Human Resources Development Operational Program 2007-2013, Project No. POSDRU/159/1.5/S/132765.Background: The main goal of the current work was to infer the demographic history of seven Spanish goat breeds (Malagueña, Murciano-Granadina, Florida, Palmera, Mallorquina, Bermeya and Blanca de Rasquera) based on genomewide diversity data generated with the Illumina Goat SNP50 BeadChip (population size, N = 176). Five additional populations from Europe (Saanen and Carpathian) and Africa (Tunisian, Djallonké and Sahel) were also included in this analysis (N = 80) for comparative purposes. Results: Our results show that the genetic background of Spanish goats traces back mainly to European breeds although signs of North African admixture were detected in two Andalusian breeds (Malagueña and MurcianoGranadina). In general, observed and expected heterozygosities were quite similar across the seven Spanish goat breeds under analysis irrespective of their population size and conservation status. For the Mallorquina and Blanca de Rasquera breeds, which have suffered strong population declines during the past decades, we observed increased frequencies of large-sized (ROH), a finding that is consistent with recent inbreeding. In contrast, a substantial part of the genome of the Palmera goat breed comprised short ROH, which suggests a strong and ancient founder effect. Conclusions: Admixture with African goats, genetic drift and inbreeding have had different effects across the seven Spanish goat breeds analysed in the current work. This has generated distinct patterns of genome-wide diversity that provide new clues about the demographic history of these populations

Evaluation of the renal function in patients with nephrectomy

Foundation: several studies have been published by different groups of work about the evaluation of the renal function in nephrectomized patients, showing varied results. In some cases it is reported the deterioration of the remaining kidney, and not in others. Objective: to describe the adaptative response regarding renal and clinical evolution in nephrectomized patients. Methods: cross study in which it was evaluated the renal function before and at two years of nephrectomy of 38 patients. The variables analyzed were glomerular filtration rate, creatinine and serum urea and associated diseases. Rates, percentages and Squared Chi for qualitative variables so as mean, standard deviation and Students T test for quantitative ones. Results: serum creatinine mean after nephrectomy was superior to the pre-nephrectomy (102 umol vs 126) p=0,05. Glomerular Filtration rate decreased after nephrectomy (62 ml/min vs 43 ml/min) p=0,02. Hypertensive and diabetic patients had a higher deterioration of the renal function, p≤0,05. Conclusion: nephrectomy produces a deterioration of the renal function at two years of follow up mainly in diabetic and hypertensive patients

Aspectos tectónicos del estudio gravimétrico de la Cuenca de Málaga

This work shows the results o f a gravimetric survey carried out in the Malaga Basin (sited on the Internal Zone o f the Western Betic Chain, southern Spain). Three anomalies maps are exposed and interpreted, focusing on neotectonic aspects. In order to avoid the influence of peridotitic bodies which outcrop in the studied area, and the southward thinning of the crust, a regional anomaly map has been processed and subtracted to the Bouguer anomaly. So, a residual anomaly map has been reached, where neotectonic interpretation has been done. The main tectonic feature evidenced by gravimetric data is the Albornoque Fault. It represents the southern boundary o f the Malaga Basin with a noticeable vertical component, according to its high gradient. By other hand, the fold o f Sierra de Cartama is marked by a maximum axis. This axis continues westward giving a duplicated depocenter of the basin. It is interpreted as a reverse fault, related in depth with the folding o f Sierra de Cartama, and which affects the basement o f the basin. According with the current stress field in the zone (NNW-SSE), the proposed structures imply the existence o f a compressive neotectonic activity, where the Albornoque fault is interpreted as a high angle reverse fault o f a reverse faul