Influence of temperature on high molecular weight poly(lactic acid) stereocomplex formation

The influence of temperature on the formation of high molecular weight poly(lactic acid) (PLA) stereocomplex was studied by evaluation of the precipitates from dioxane solutions of PLA enantiomers (PLLA and PDLA). The racemic mixtures were characterized by Gel Permeation Chromatography, Infrared Spectroscopy, Differential Scanning Calorimetry, Scanning Electronic Microscopy, Wide-Angle X-ray Scattering and Vicat Softening Temperature. Precipitation was carried out under different solution temperatures, keeping constant the mixing ratio (XD), the molecular weight, the optical purity of both PLA enantiomers and the stirring rate. It was found that the precipitates contained only pure stereocomplex crystallites (racemic crystallites), without observing crystal phase separation between both homocrystals. The kinetics of the insoluble phase formation could be adjusted with the Avrami model, classically used for polymer crystallization in molten state. It was observed that the maximum PLA stereocomplex production rate was at about 40°C. However, more thermally stable racemic crystallites were formed at high solution temperatures. It was found that all the precipitates were sphere-like at 10 g·dl–1 at the solution temperature of 25, 40, 60 and 80°CPeer ReviewedPostprint (author's final draft

Effect of the annealing procedure and the molecular weight on the crystalline phase morphology and thermal properties of polylactide

"This is the peer reviewed version of the following article: Hortós, M. , Anakabe, J. , Arrillaga, A. , Espino, S. and Bou, J. J. (2019), Effect of the annealing procedure and the molecular weight on the crystalline phase morphology and thermal properties of polylactide. Polym. Int., 68: 1767-1775, which has been published in final form at https://doi.org/10.1002/pi.5887. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions."The thermomechanical properties of poly(lactide) (PLA) are strongly related to its semicrystalline microstructure and morphology. Thermal annealing is a strategy to improve the crystallinity of PLA. However, the different techniques and specimen types needed for each kind of characterization could lead to misleading conclusions. In this work, annealed samples of three PLA grades with different molecular weights were studied by DSC, wide angle X-ray scattering and polarized optical microscopy (POM) and the results are related to their thermomechanical and impact properties. Special focus is put on the POM results obtained by different approaches and the suitability of each of them to be related to the thermomechanical properties. By annealing medium molecular weight PLA specimens at 140 °C an important increase of the heat distortion temperature was obtained, which was not related to the spherulite size but to the combination of high crystallinity degree together with high a/a' crystal type ratio. However, the impact properties of annealed PLA decreased with increase in the annealing temperature according to an increment in crystallinity and in the a/a' crystal ratio.Peer ReviewedPostprint (author's final draft

PLA/PCL ecoblends: Effect of PCL addition on the toughness of PLA

El comportamiento a fractura de una “Ecoblend” de Poli(Ácido Láctico) (PLA) con Poli(Caprolactona) (PCL) adecuadamente compatilibilizada ha sido estudiado y comparado con el PLA base. El estudio se llevó a cabo sobre probetas de tipo SENB obtenidas a partir de barras prismáticas (4x10 mm) producidas mediante moldeo por inyección. Para asegurar condiciones ideales de fisura aguda y reproducibilidad de resultados, tras el entallado mecánico se agudizó mediante ablación por láser pulsante en femtosegundos (femtoláser). Aplicando la teoría de mecánica de la fractura elástico lineal, el factor provisional de intensificación de tensiones (KQ) y el trabajo específico de fractura (wf) (parámetro alternativo a la resistencia al impacto estandarizada) fueron determinados siguiendo la metodología de monoentalla (a/w=0.45) con 5 réplicas a velocidades de soliticación moderamente altas (1 m.s-1, impacto instrumentado en configuración Charpy). La fase PCL promueve un incremento en 1,5 veces en KQ y de 7 veces en wf. Las evidencias fractográficas revela que la deformación y la cavitación de la fase PCL promueven el alivio de la triaxialidad local, lo que puede causar un aumento de la tensión hidrostática local necesaria para iniciar las crazes y su posterior ruptura en condiciones de impacto. A a bajas velocidades de solicitación (ensayos de tracción), este proceso de cavitación/fibrilación suprime los fenómenos de crazing de la matriz de PLA favoreciendo su cedencia y deformación plástica.Peer ReviewedPostprint (published version

Plan de negocios de “Después del Cole”: una plataforma web dedicada a la comunicación entre jóvenes entre 14 a 18 años y universidades e institutos en Lima Metropolitana

El presente plan de negocios bajo la razón social “ Después del Cole S.A.C“ tiene como fin el desarrollo de un ecosistema digital, el cual tiene como eje central a la website, en donde se brindará información relevante acerca de carreras profesionales y técnicas para los jóvenes, y a su vez, contenido de orientación vocacional sobre las carreras profesionales y las casas de estudios superiores en Lima Metropolitana (Universidad privadas e Institutos privados), las cuales están interesados en anunciar, contactar e interactuar con el segmento juvenil y el presente modelo de negocio será el medio ideal para ello. El plan de negocios se desarrolló en 8 capítulos: En el Capítulo I se plantea la idea del negocio, se trazan los objetivos, metodología de la investigación y la justificación. En el Capítulo II un marco teórico, en donde se analizan problemáticas de la educación peruana en búsqueda de oportunidades, con enfoque en el sector privado, universidades privadas e institutos técnicos, plataformas digitales, sitios web en el Perú, contenido digital, monetización y redes sociales. El Capítulo III presenta el análisis del negocio, en él encontramos el planteamiento del problema, análisis del entorno, análisis interno y el análisis Foda. El Capítulo IV corresponde a la validación de la idea del negocio a través de sondeos de mercado. En el Capítulo V se desarrolla el modelo de negocio y se establecen la Misión, Visión y Valores, el Value Proposition Canvas de Usuarios y Entidades Educativas, journey map y el lienzo del modelo de negocios canvas. El Capítulo VI desarrolla el plan de marketing y se presenta al mercado de consumidores, formulación estratégica y tácticas. El Capítulo VII muestra el plan de operaciones, en donde detallamos la definición de los servicios, políticas del servicio, información de la empresa, estrategia de operaciones, procesos y recursos humanos. Finalmente en el Capítulo VIII desarrollamos el plan económico financiero, donde se demuestra la viabilidad financiera del proyecto, el flujo de caja, estado de resultados y el estado financiero.The purpose of this business plan under the name of "Después del Cole S.A.C" is the development of a digital ecosystem, whose central axis is the web site, where relevant information about all the private universities and institutes from Metropolitan Lima and the professional and technical careers they hold will be provided for young people who are eager to start their professional studies. Additionally, as a content marketing strategy, this website will create digital content specialized in vocational guidance in order to converge the universities’ target with our platform. In such a manner, private institutes and universities will be interested in announcing, contacting, and interacting with our website’s public. This business plan is divided into 8 chapters. Chapter I, where presentation of the business idea, objectives, research methodology and justification are outlined. Chapter II, theoretical framework’s exposition, where we will study the main problems of Peruvian education with a focus on the private sector, private universities and technical institutes. Furthermore, study of digital platforms, websites in Peru, digital content, monetization and social networks. Chapter III presents the business analysis, where we decrypt the problem statement, environment analysis, internal analysis or SWOT analysis and other frameworks. Chapter IV corresponds to the validation of the business idea through market surveys. In Chapter V the business model is developed, this includes the Mission, Vision and Values, the Value Proposition Canvas for the website users and Educational Entities, the journey map and the business model canvas are also established. Chapter VI develops the marketing plan and it presents the consumer market, creative concepts for strategic formulation and tactics. Chapter VII shows the operations plan, where we detail the definition of services, service policies, company information, operations strategy, processes and human resources. Finally, in Chapter VIII we develop the financial economic plan, where the financial viability of the project is proven, the cash flow, the income statement and the financial statement are demonstrated.Trabajo de investigació

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Mejora del proceso de producción de anchoas para mitigar el riesgo de contaminación deliberada en una empresa peruana dedicada al curado de anchoas, 2022

El estudio de investigación denominado “Mejora del proceso de producción de anchoas para mitigar el riesgo de contaminación deliberada en una empresa peruana dedicada al curado de anchoas, 2022” planteó como objetivo general desarrollar una mejora en el proceso de producción de anchoas para mitigar el riesgo de contaminación deliberada en una empresa peruana dedicada al curado de anchoas, 2022. Para lo cual se formuló el siguiente problema general: ¿De qué forma se puede lograr una mejora en el proceso de producción de anchoas mitiga el riesgo de contaminación deliberada en una empresa peruana dedicado al curado de anchoas, 2022?, de igual manera la hipótesis general planteada fue la siguiente: la mejora en el proceso de producción de anchoas mitiga el riesgo de contaminación deliberada en la empresa peruana. La investigación fue aplicada con nivel aplicativo-explicativo, empleando un diseño preexperimental. Para la recolección de datos, las técnicas usadas fueron el análisis documental y la encuesta, mientras que los instrumentos fueron cuestionario de preguntas, registros, Checklist y otros. Los resultados hallados fueron los siguientes: los riesgos promedios de contaminación deliberada fueron de 92.8 % y se obtuvo una reducción del 50 a 60 % con la propuesta, asimismo, las estrategias de mitigación representaron un orden del 90 %, en la ejecución del plan de defensa alimentaria habiendo reducido hasta 70 %, la propuesta del estudio es que estos últimos lleguen al 100 % con las mejoras señaladas

Influence of temperature on high molecular weight poly(lactic acid) stereocomplex formation

The influence of temperature on the formation of high molecular weight poly(lactic acid) (PLA) stereocomplex was studied by evaluation of the precipitates from dioxane solutions of PLA enantiomers (PLLA and PDLA). The racemic mixtures were characterized by Gel Permeation Chromatography, Infrared Spectroscopy, Differential Scanning Calorimetry, Scanning Electronic Microscopy, Wide-Angle X-ray Scattering and Vicat Softening Temperature. Precipitation was carried out under different solution temperatures, keeping constant the mixing ratio (XD), the molecular weight, the optical purity of both PLA enantiomers and the stirring rate. It was found that the precipitates contained only pure stereocomplex crystallites (racemic crystallites), without observing crystal phase separation between both homocrystals. The kinetics of the insoluble phase formation could be adjusted with the Avrami model, classically used for polymer crystallization in molten state. It was observed that the maximum PLA stereocomplex production rate was at about 40°C. However, more thermally stable racemic crystallites were formed at high solution temperatures. It was found that all the precipitates were sphere-like at 10 g·dl–1 at the solution temperature of 25, 40, 60 and 80°CPeer Reviewe

Análisis de la cadena de valor del café liofilizado a través de la metodología Delphi y propuestas competitivas

Currently, the Peruvian lyophilized coffee value chain has a discrete participation with respect to its competitors in the international market. The main objective of the research was to analyze the value chain of Peruvian lyophilized coffee, identifying comparative and competitive advantages in international markets. The methodology used was a mixed approach with a quasi-experimental design. Based on the current value chain mapping and the current design of the supply chain of Peruvian lyophilized coffee, it was possible to analyze with greater precision the main problems presented by the links that make up the value chain, in order to design a model that generates value proposals in the production and commercialization of Peruvian coffee, and that are capable of contributing to the competitiveness of Peruvian lyophilized coffee in international markets.Actualmente la cadena de valor del café liofilizado peruano cuenta con una participación discreta respecto a sus competidores en el mercado internacional. El objetivo principal de la investigación fue el análisis de la actual cadena de valor del café liofilizado peruano, identificando ventajas comparativas y competitivas en los mercados internacionales. La metodología que se empleó fue de enfoque mixto y con diseño cuasi experimental. A partir del mapeo actual de la cadena de valor y el diseño actual de la cadena de suministro del café liofilizado peruano, se permitió analizar con mayor precisión los principales problemas que presentaban los eslabones que conformaban la cadena de valor, para poder diseñar un modelo propuesto que abarque desde la producción primaria del café hasta la comercialización del café liofilizado peruano, que sea capaz de aportar en la competitividad del café en los mercados internacionales.&nbsp

Effect of the annealing procedure and the molecular weight on the crystalline phase morphology and thermal properties of polylactide

"This is the peer reviewed version of the following article: Hortós, M. , Anakabe, J. , Arrillaga, A. , Espino, S. and Bou, J. J. (2019), Effect of the annealing procedure and the molecular weight on the crystalline phase morphology and thermal properties of polylactide. Polym. Int., 68: 1767-1775, which has been published in final form at https://doi.org/10.1002/pi.5887. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions."The thermomechanical properties of poly(lactide) (PLA) are strongly related to its semicrystalline microstructure and morphology. Thermal annealing is a strategy to improve the crystallinity of PLA. However, the different techniques and specimen types needed for each kind of characterization could lead to misleading conclusions. In this work, annealed samples of three PLA grades with different molecular weights were studied by DSC, wide angle X-ray scattering and polarized optical microscopy (POM) and the results are related to their thermomechanical and impact properties. Special focus is put on the POM results obtained by different approaches and the suitability of each of them to be related to the thermomechanical properties. By annealing medium molecular weight PLA specimens at 140 °C an important increase of the heat distortion temperature was obtained, which was not related to the spherulite size but to the combination of high crystallinity degree together with high a/a' crystal type ratio. However, the impact properties of annealed PLA decreased with increase in the annealing temperature according to an increment in crystallinity and in the a/a' crystal ratio.Peer Reviewe