Alkaline pretreatment of Mexican pine residues for bioethanol production

The locally sourced residue samples of Pinus arizonica, Pinus cooperi, and Pinus durangensis from the state of Durango in Mexico were analyzed for optimal yield of ethanol production. The samples were mixed at an equal proportion using a particle size of 0.59 mm. Each individual mixture was pretreated with either NaOH or Ca (OH)2 (at 0.5, 1.0 and 1.5% w/v) for periods of 30, 60, and 90 min at 60, 90, and 120°C. The pretreated blending was subjected to enzymatic hydrolysis for 130 h at 80 rpm and 50°C with an enzymatic load of 25 filter paper units (FPU) and 50 IU β-glucosidase per gramme of cellulose to obtain a maximum yield of reducing sugars (RS) with NaOH subject at 120°C for 90 min. The results show that the hydrolysis yield depends on temperature and alkali concentration particularly (NaOH), which increased from 2.0 to 3.5% w/v. The best yield of glucose (41.33% w/w) was obtained using a pretreatment of 2.5% NaOH for 90 min, 120°C, and a hydrolysis residence time of 130 h. The removal of lignin and hemicellulose acetylation was observed to have influence on the enzymatic digestibility of cellulose. This process could theoretically produce a maximum yield of 90.19% of ethanol / substrate (glucose) and about 80 L of bioethanol per dry ton of woody biomass from pine residues.Keywords: Lignocellulosic biomass, alkaline pretreatment, enzymatic hydrolysis, fermentable sugars, fermentationAfrican Journal of Biotechnology Vol. 12(31), pp. 4956-496

Rotura del núcleo de polietileno en cotilo no cementado

La rotura del componente de polietileno de los cotilos en la prótesis total de cadera, es una complicación raramente descrita, sobre todo en artroplastias no cementadas. Presentamos un caso de rotura del polietileno en una prótesis total de cadera no cementada, revisando los 15 casos previamente publicados. Nuestro propósito es alertar sobre la posibilidad de esta infrecuente complicación.Fracture of the polyethylene liner of uncemented acetabular components is rarely mentioned in the literature. One case of fracture of the polyethylene liner is uncementeed his arthroplasty is described and we review 15 cases previously reported. The purpose of the report is to alert about this rare complication

Colombian fruit and vegetables recognition using convolutional neural networks and transfer learning

Automatic image recognition is a convenient option for labeling and categorizing fruits and vegetables in supermarkets. This paper proposes the design and implementation of an automatic classification system for Colombian fruits, by training a convolutional neural network. A database was created to train and test the system, which consisted of 4980 images, labeled in 22 classes, each corresponding to pictures of the same kind of fruit, trying to reproduce the variability of a real case scenario with occlusions, different positions, rotations, lightings, colors, etc., and the use of bags. On-training data augmentation was used to further increase the robustness of the model. Additionally, transfer learning was implemented by taking the parameters of a pretrained model used for fruit classification as the new initial parameters of the proposed convolutional network, achieving an increase of the classification accuracy compared with the same model when trained with random initial weights. The final classification accuracy of the network was 98.12% which matches the scores achieved on previous works that performed fruit classification on less challenging datasets. Considering top-3 classification we report an accuracy of 99.95%. © 2020 IOP Publishing Ltd. All rights reserved

Novel dual single sided silicon strip detector chip for radiotherapy verification

A novel dual single sided silicon strip detector (SSSSD) chip was designed to meet clinical requirements in radiotherapy verification. An available design from Micron Semiconductor Ltd. (BB7, 500 µ m thick) was the base of a two-dimensional detector adapted into a special configuration with the aim of uniforming and minimizing foreing materials around the active area (64 × 64 mm2). With this purpose, two independent BB7 SSSSDs were mounted in a perpendicular configuration, separated by a 500 µ m kapton dielectric film with the same dimensions as the silicon wafers, thus minimizing air gaps in between. This new configuration, called the dual SSSSD chip design, was mounted on kapton printed circuit board (PCB). Both silicon wafers were divided into 32 strips, 2 mm width each. The aim of developing this detector was to allow 2D dose measurements, improve spatial resolution and perform radiotherapy treatment verification faster than with a previous prototype. Characteristics and performance of the novel detector are presented

Entre la decolonización y el capital humano. reflexiones en torno al rol esperado del docente en el Chile post transición

The relationship between socioeconomic mobility and school levels has been thematized since the generalization of modern institutionalized education systems. The demand for Chilean quality education is associated with exitism and the formation of Human Capital, crashing with mismatches between public policies, the crisis of legitimization of public education, and the Latin American epistemic advance that influences the pedagogical exercise through critical pedagogy or decolonization as a new way of organizing / re-creating knowledge. Thus, the teacher is required from two dichotomous currents, which makes him a vortex with unusual edges. This article of reflection seeks to expose some aspects of these contradictions, addressing the theory of Human Capital in education and the decolonization of pedagogy, in relation to the expected role of teachers in Chile.La relación entre movilidad socioeconómica y niveles escolares se ha tematizado desde la generalización de los sistemas institucionalizados modernos de educación. La exigencia de educación de calidad chilena está asociada al exitismo y a la formación de Capital Humano, estrellándose con desajustes entre políticas públicas, la crisis de legitimación de la educación pública, y el avance epistémico latinoamericano que influye el ejercicio pedagógico a través de la pedagogía crítica o la descolonización como nueva forma de organizar/re-crear conocimiento. Es así que el docente es requerido desde dos corrientes dicotómicas, lo que le convierte en un vórtice con inusitadas aristas. El presente artículo de reflexión busca exponer algunos aspectos de dichas contradicciones, abordando la teoría de Capital Humano en educación y de la decolonización de la pedagogía, en relación al rol esperado del profesorado en Chile

Entre la decolonización y el capital humano. reflexiones en torno al rol esperado del docente en el Chile post transición

The relationship between socioeconomic mobility and school levels has been thematized since the generalization of modern institutionalized education systems. The demand for Chilean quality education is associated with exitism and the formation of Human Capital, crashing with mismatches between public policies, the crisis of legitimization of public education, and the Latin American epistemic advance that influences the pedagogical exercise through critical pedagogy or decolonization as a new way of organizing / re-creating knowledge. Thus, the teacher is required from two dichotomous currents, which makes him a vortex with unusual edges. This article of reflection seeks to expose some aspects of these contradictions, addressing the theory of Human Capital in education and the decolonization of pedagogy, in relation to the expected role of teachers in Chile.La relación entre movilidad socioeconómica y niveles escolares se ha tematizado desde la generalización de los sistemas institucionalizados modernos de educación. La exigencia de educación de calidad chilena está asociada al exitismo y a la formación de Capital Humano, estrellándose con desajustes entre políticas públicas, la crisis de legitimación de la educación pública, y el avance epistémico latinoamericano que influye el ejercicio pedagógico a través de la pedagogía crítica o la descolonización como nueva forma de organizar/re-crear conocimiento. Es así que el docente es requerido desde dos corrientes dicotómicas, lo que le convierte en un vórtice con inusitadas aristas. El presente artículo de reflexión busca exponer algunos aspectos de dichas contradicciones, abordando la teoría de Capital Humano en educación y de la decolonización de la pedagogía, en relación al rol esperado del profesorado en Chile