10 research outputs found
Comparison of saccharification and fermentation of steam exploded rice straw and rice husk
Survey data on the impact of COVID-19 on parental engagement across 23 countries
This data article describes the dataset of the International COVID-19 Impact on Parental Engagement Study (ICIPES). ICIPES is a collaborative effort of more than 20 institutions to investigate the ways in which, parents and caregivers built capacity engaged with children's learning during the period of social distancing arising from global COVID-19 pandemic. A series of data were collected using an online survey conducted in 23 countries and had a total sample of 4,658 parents/caregivers. The description of the data contained in this article is divided into two main parts. The first part is a descriptive analysis of all the items included in the survey and was performed using tables and figures. The second part refers to the construction of scales. Three scales were constructed and included in the dataset: 'parental acceptance and confidence in the use of technology', 'parental engagement in children's learning' and 'socioeconomic status'. The scales were created using Confirmatory Factor Analysis (CFA) and Multi-Group Confirmatory Analysis (MG-CFA) and were adopted to evaluate their cross-cultural comparability (i.e., measurement invariance) across countries and within sub-groups. This dataset will be relevant for researchers in different fields, particularly for those interested in international comparative education
Efecto de sorbato de potasio como agente de interfase en bicapas a base de polímeros biodegradables
Studies that are focused on the design and development of biodegradable materials with promising physicochemical properties forindustrial use have been of great importance. In this research, bilayer materials were developed using thermoplastic starch (TPS)monolayers assembled with monolayers sheets of amorphous polylactic acid (PLAa) and polycaprolactone (PCL). Potassiumsorbate was evaluated as an interfacial adhesion material. Structural properties of the laminated materials (FTIR and SEM),behaviour with water (rate of water vapour transmission, solubility in water and moisture content) and biodegradation of thematerials were evaluated. Potassium sorbate was found to act as a promising interface agent by increasing adhesion betweenpolymer layers (SEM). The FTIR showed marked changes in the bands of the hydroxyl and carbonyl groups. Due to PLAaand PCL’s hydrophobic character, all bilayers showed excellent barrier properties against water vapor. Finally, the bilayers thatdegrade the fastest are PCL/TPS. These laminated materials are a great alternative to the decrease in the use of conventionalplastics and are applicable as packaging in the food industry.Estudios enfocados en el diseño y desarrollo de materiales biodegradables con propiedades fisicoquímicas prometedoras parasu uso industrial han sido de gran importancia. En esta investigación se desarrollaron materiales bicapa mediante monocapasde almidón termoplástico (TPS) ensambladas con monocapas de ácido poliláctico amorfo (PLAa) y policaprolactona (PCL). Elsorbato de potasio se evaluó como material de adherencia interfacial. Se evaluaron propiedades estructurales de los materialeslaminados (FTIR y SEM), comportamientos con el agua (tasa de transmisión del vapor de agua, solubilidad en agua y contenidode humedad) y biodegradación del material. Se encontró que el sorbato de potasio actúa como un agente de interfaz prometedoral aumentar la adhesión entre las capas de polímero (SEM). El FTIR mostró cambios marcados en las bandas de los gruposhidroxilo y carbonilo. Debido al carácter hidrófobo de PLAay PCL, todas las bicapas mostraron excelentes propiedades debarrera contra el vapor de agua. Finalmente, las bicapas que se degradan más rápido son PCL/TPS. Estos materiales laminadospresentan un gran potencial para el remplazo de plásticos de uso habitual y su aplicación como empaques en la industria dealimentos
Active biodegradable films based on thermoplastic starch and poly (e-caprolactone): technological application of antioxidant extracts from rice husk
Films of a polymeric material based on cassava starch and polyε-caprolactone (PCL) with antioxidant properties were made.The influence of PCL and the antioxidant extract were evaluated, over the mechanical, thermal and chemical properties of thefilms. They were elaborated with, and without the antioxidant extract, which is rich in polyphenolic compounds. The films wereconditioned at 20°C and 53% RH. The antioxidant extract was obtained from rice husk, by the hot water methodology in ahigh-pressure reactor, at 160°C and 10 bar. The total phenolic content of the extract was 12.27 (mEAG/100g dry matter), and theantioxidant activity had a value of 6691.95 (mETRX/100g dry matter). The extract was incorporated into a thermoplastic starchand poly E-caprolactone matrix, and films by compression molding were obtained. The antioxidant capacity was evaluatedby DPPH method, where the lesser value was 1.54 (kg film/g DPPH) from EC50, it was found that the addition of PCL andantioxidant improved the general properties of the films.Se realizaron películas a base de almidón de yuca y poliε-caprolactona (PCL), con propiedades antioxidantes. Se evaluóla influencia de la adición de PCL y el extracto antioxidante sobre las propiedades mecánicas, térmicas y químicas de laspelículas. Las películas fueron elaboradas con y sin extracto antioxidante rico en compuestos polifenólicos, las películas fueronacondicionadas a 20 °C y 53% HR. El extracto antioxidante se obtuvo de la cascarilla de arroz, mediante la metodología de aguacaliente, en un reactor de alta presión a 160 °C y 10 bar. El contenido fenólico total del extracto fue 12.27 (mEAG/100g masaseca), y se obtuvo un valor de 6691.95 (mETRX/100g masa seca) de actividad antioxidante. El extracto se incorporó a la matrizde almidón termoplástico y poli E-caprolactona, y se obtuvieron películas por moldeo con presión. La capacidad antioxidantede las películas se evaluó mediante el método de DPPH, donde el menor valor de EC50fue de 1.54 (kg película/g DPPH), seencontró que la adición de PCL y extracto antioxidante mejoró en general las propiedades de las películas
Bi-layer materials based on thermoplastic corn starch, polylactic acid and modified polypropylene
Currently, the development of environmentally friendly materials with suitable properties for industrial use has become ofgreat importance. In this work, bilayer materials were developed by assembling thermoplastic- corn starch monolayers (TPS)combined with semi-crystalline polylactic acid (PLAs) monolayers and maleic anhydride grafted polypropylene (PPMA). Thepresence of a potassium sorbate solution was evaluated as interface material. Structural properties (FTIR and SEM), interactionswith water (water vapor transmission rate, solubility in water and moisture content) and biodegradation of the materials wereevaluated. FTIR spectra showed that potassium sorbate promotes chemical interactions between TPS monolayers (-OH group)and PLA monolayers (C=O group) or PPMA(C-O-C, C-O, C-H groups). For their part, SEM micrographs reveal that whenadding potassium sorbate, higher interfacial adhesion develops between TPS and PPMAthan between TPS and PLAs. As for theinteractions with water, when using a PLA or PPMAmonolayer, due to its hydrophobic characteristics, the high permeability towater vapour and the sensitivity to liquid water that starch-based materials present would be avoided. Finally, the biodegradationtest showed that TPS biodegrades faster than other materials, followed by PLA. The results obtained are interesting since theaddition of an adhesive material to assemble the low chemical affinity monolayers would be avoided. The developed materialsexhibit great potential for application as packaging in the food industry.En la actualidad ha cobrado gran importancia el desarrollo de materiales amigables con el medio ambiente y que tenganpropiedades fisicoquímicas adecuadas para su uso industrial. En este trabajo se desarrollaron materiales bicapa medianteel ensamblaje de monocapas de almidón de maíz termoplástico (TPS) combinadas con monocapas de ácido polilácticosemicristalino (PLAs) y polipropileno agrafado con anhídrido maleico (PPMA). Como material de interfase se evaluó la presenciade una disolución de sorbato de potasio. Se evaluaron propiedades estructurales (FTIR y SEM), interacciones con el agua(tasa de transmisión del vapor de agua, solubilidad en agua y contenido de humedad) y biodegradación de los materiales. Losespectros FTIR mostraron que el sorbato potasio promueve interacciones químicas entre los monocapas de TPS (grupo -OH) ylos monocapas de PLAs(grupo C=O) o PPMA(grupos C-O-C, C-O, C-H). Por su parte, las micrografías SEM revelan que, aladicionar sorbato de potasio, se desarrolla mayor adhesión interfacial entre TPS y PPMAque entre el TPS y PLAs. En cuantoa la interacciones con el agua, al usar un monocapa de PLAso PPMA, por sus características hidrofóbicas, se evitaría la altapermeabilidad al vapor de agua y sensibilidad al agua líquida que presentan los materiales a base de almidón. Finalmente, laprueba de biodegradación mostró que el TPS se biodegrada a mayor velocidad que los demás materiales, seguido por el PLAs.Los resultados obtenidos son interesantes puesto que se evitaría la adición de un material adhesivo para ensamblar los monocapasde baja afinidad química. Los materiales desarrollados presentan gran potencial de aplicación como empaques en la industria dealimentos