Abstract: Cellulose nanofibers (CNF) could be obtained from diverse lignocellulosic sources, among them wood. Regarding this, it is important to clarify if the shaft section of the tree could influence the CNF characteristics. This study evaluated cellulose nanofibers from Guazuma crinita (bolaina blanca) obtained at different heights of the longitudinal axis of the shaft of trees from a three-and-a-half-year-old plantation. The wood was subjected to pulping, bleaching and subsequent mechanical milling using a Changsha Samy XYQM-2L planetary ball mill to obtain cellulose nanofibers. The product was characterised using analytical techniques: scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy. Additionally, the degree of polymerisation was determined. The effect of longitudinal position on cellulose nanofibers characteristics was evaluated by comparing means using ANOVA and Kruskal-Wallis statistical tests. The yield of cellulose nanofibers production from the high, middle and basal sections was 32,1 %, 33,6 % and 31 %, respectively. The obtained cellulose nanofibers exhibited a significantly larger diameter for the high zone (84 nm) compared with the middle (75 nm) and basal (69 nm) zones; the length remained above the micrometre range. With respect to degree of polymerisation, a decrease was evidenced with respect to the increase in shaft height; the basal zone exhibited a degree of polymerisation of 300, a significantly higher value than the middle and high zones, which exhibited degree of polymerisation of 249 and 211, respectively. The product showed typical cellulose type I polymorphism and crystallinity indexes of 76 %, 93 % and 96 % for the high, middle and basal sections, respectively. Regarding the thermostability of cellulose nanofibers, the maximum degradation rate of cellulose nanofibers occurred between 335 °C and 341 °C, with cellulose nanofibers from the basal area being the most stable. The adsorption of the methylene blue dye on cellulose nanofibers was evaluated; an efficiency > 60 % was found.

RESUMEN Fundamentos: La enfermedad hepática grasa asociada a disfunción metabólica (MAFLD) es una enfermedad poco considerada, que ha recibido atención debido al número de casos en países como México, donde ocupa el 4º lugar mundial de incidencia. La MAFLD se desarrolla en personas con sobrepeso u obesidad y se caracteriza por la acumulación de triglicéridos en el hígado, donde puede evolucionar hacia carcinoma hepatocelular. Se ha observado que la MAFLD depende de la genética y del estilo de vida. Tomando en cuenta la alta prevalencia de MAFLD en la población hispana, nos enfocamos en este trabajo en estudiar la prevalencia y características relacionadas con esta enfermedad en pacientes mexicanos. Métodos: En este estudio se incluyeron 572 pacientes con sobrepeso u obesidad, a los cuales se les realizó un análisis de cribado mediante el índice de hígado graso (IHG), se analizaron parámetros clínicos, demográficos y comorbilidades. Se obtuvieron frecuencias de las variables y se analizaron los datos mediante chi cuadrado o exacta de Fisher, razón de momios (OR) y regresión logística binaria. Resultados: Se obtuvo una prevalencia del 37% de MAFLD, donde la historia familiar de obesidad, el uso de paracetamol, así como el consumo de carbohidratos y grasas fueron factores de riesgo para su desarrollo. Se encontró que la hipertensión arterial, la obesidad visceral y la hipertrigliceridemia también estaban asociados al desarrollo de la MAFLD. Por otro lado, el ejercicio fue un factor protector. Conclusiones: Nuestros resultados ponen de manifiesto la necesidad de realizar estudios relacionados con las causalidades de la MAFLD en los pacientes mexicanos, principalmente en el uso del paracetamol.

ABSTRACT Background: Metabolic dysfunction-associated fatty liver disease (MAFLD) is a poor attended disease, which has gained attention due the elevated number of cases in countries as Mexico, where the incidence is the number 4th globally. MAFLD develops in obese or overweighted individuals and is characterized by triglycerides accumulation in the liver, this condition can develop to hepatocellular carcinoma. It has been observed that MAFLD depends on the genetics and lifestyle. Due to the high prevalence of this disease among Hispanic population, we focused on this study in the characteristics and prevalence of MAFLD in Mexican patients. Methods: In this study were included 572 overweighted and obese patients, who underwent a screening analysis using the fatty liver index (IHG), clinical parameters were analysed, demographic and comorbidities. Frequency of variables were obtained, and the data were analysed by Chi-square test or Fisher test, odd ratio (OR) and binary logistic regression. Results: A MALFD prevalence of 37% were obtained, where the history of familiar obesity, paracetamol usage, carbohydrate and fat intake are shown to be risk factors. It was found that high blood pressure, central obesity and hypertriglyceridemia were also associated to the MAFLD development. On the other hand, physical exercise was a protector factor. Conclusions: Our results show the necessity to study the MAFLD causalities in Mexican patients, focused on the paracetamol intake.

Resumen En la presente investigación se analizan los conocimientos en matemáticas que tienen los estudiantes de primer ingreso de las licenciaturas de Administración, Turismo, Contaduría Pública, Tecnologías de la Información y las ingenierías en Mecatrónica, Electrónica y Computación, Instrumentación Electrónica y Nanosensores, Diseño Molecular de Materiales, Geofísica y Sistemas Biológicos. Se trata de identificar los conocimientos básicos y las deficiencias de los alumnos en esta área antes de cursar asignaturas como Matemáticas I o Precálculo (según sea el caso) para contribuir a erradicar la reprobación, el rezago y el posible abandono de los estudios de licenciatura. Se aplicó una prueba que consta de 15 reactivos de opción múltiple a 413 estudiantes de dichos programas educativos. Una vez realizado el análisis, se encontró 44.20 % de respuestas incorrectas, 52.98 % de respuestas correctas y 2.82 % de respuestas sin contestar. Se obtuvo una calificación promedio de 52.97 (reprobatoria); solo tres estudiantes contestaron correctamente los 15 reactivos; un estudiante acertó solo uno del total de reactivos. El reactivo 13, donde se requiere expresar algebraicamente el perímetro de un rectángulo a partir de una expresión verbal, obtuvo el mayor número de respuestas incorrectas, con 11.56 %. El reactivo 14, que consiste en identificar el procedimiento para resolver una ecuación de primer grado con una incógnita, registró el mayor número de respuestas correctas, con 10.69 %. Los programas que obtuvieron un promedio mayor al general (52.97) fueron las ingenierías en Mecatrónica, en Instrumentación Electrónica y Nanosensores, en Diseño Molecular de Materiales, en Geofísica y la licenciatura en Contaduría Pública; el resto tuvo una nota por debajo del promedio general. Solamente en ingeniería Mecatrónica e ingeniería Geofísica se obtuvieron promedios de calificación aprobatoria. Por lo anteriormente indicado, es necesario que en todas las licenciaturas se subsanen estas carencias, apoyándose en los cursos de Matemáticas I y Precálculo, y en específico se requiere de fortalecer los conocimientos en fracciones, exponentes, jerarquía de operaciones, ley de los signos y operaciones algebraicas.

Resumo Esta pesquisa analisa os conhecimentos matemáticos dos alunos do primeiro ano do Bacharelado em Administração, Turismo, Contabilidade Pública, Tecnologia da Informação e engenharia em Mecatrônica, Eletrônica e Computação, Instrumentação Eletrônica e Nanossensores, Projeto Molecular de Materiais, Geofísica e Sistemas Biológicos. O objetivo é identificar o conhecimento básico e as deficiências dos alunos nessa área antes de cursar matérias como Matemática I ou Pré-cálculo (conforme o caso) para ajudar a erradicar o fracasso, o atraso e o possível abandono dos estudos de graduação. Um teste composto por 15 itens de múltipla escolha foi aplicado a 413 estudantes dos referidos programas educacionais. Após a análise, foram encontrados 44,20% de respostas incorretas, 52,98% de respostas corretas e 2,82% de respostas não respondidas. Foi obtida uma nota média de 52,97 (reprovada); apenas três alunos responderam os 15 itens corretamente; um aluno correspondeu a apenas um do número total de itens. O reagente 13, em que é necessário expressar algebricamente o perímetro de um retângulo a partir de uma expressão verbal, obteve o maior número de respostas incorretas, com 11,56%. O reagente 14, que consiste em identificar o procedimento para resolver uma equação de primeiro grau com uma variável desconhecida, registrou o maior número de respostas corretas, com 10,69%. Os programas que obtiveram média mais alta que a média geral (52,97) foram de engenharia em mecatrônica, instrumentação eletrônica e nanossensores, design de materiais moleculares, geofísica e graduação em contabilidade pública; o restante ficou abaixo da média geral. Somente na engenharia mecatrônica e na engenharia geofísica foram obtidas as médias das notas de aprovação. Pelo exposto, é necessário que essas deficiências sejam corrigidas em todos os graus, contando com os cursos de Matemática I e Pré-cálculo, e especificamente é necessário fortalecer o conhecimento em frações, expoentes, hierarquia de operações, lei de sinais e operações algébricas.

Abstract In this research, we analyze the knowledge in mathematics that have the first entry students of the Bachelor of Administration, Tourism, Public Accounting, Information Technology and Engineering in Mechatronics, Electronics and Computation, Electronic Instrumentation and Nanosensors, Molecular Design of Materials, Geophysics and Biological Systems. The goal is to identify the basic knowledge and the deficiencies of the students in this area before taking subjects such as Mathematics I or Pre-calculus (according to the case), so that these deficiencies do not contribute to failure, backwardness and possible abandonment of undergraduate studies. A test consisting of 15 multiple choice questions was applied to 413 students of these educational programs. As part of the analysis, it was found 44.20% of incorrect answers, 52.98% of correct answers and 2.82% of unanswered answers. An average score of 52.97 (failing) was obtained; only 3 students correctly answered the 15 questions and one student got a correct answer of the 15. The item 13, which requires to express algebraically the perimeter of a rectangle from a verbal expression, was the one that obtained the highest number of incorrect answers with 11.56%. Question 14, which consists in identifying the procedure to solve a first degree equation with an unknown, was the one that obtained the highest number of correct answers with 10.69%. The educational programs that obtained an average higher than the general average (52.97) were Mechatronics Engineering, Electronic Instrumentation and Nanosensors, Molecular Design of Materials, Geophysics and the Bachelor of Public Accounting; the rest had an average below the general average. Only Mechatronic Engineering and Geophysical Engineering students obtained passing grades averages. It is necessary that all bachelor's degrees correct these gaps, relying on the courses of Mathematics I and Precalculus. It is necessary to strength knowledge of fractions, exponents, hierarchy of operations, law of signs, and algebraic operations.