Layered double hydroxides (LDHs) and related materials have been studied for a long time and their application in catalytic processes remain attractive due to the tuned properties, morphologies and metal-support interactions obtained from a variety of composition and synthesis route. In this mini-review, some important reactions, such as photocatalysis, electrocatalysis, reduction, carbon-carbon cross-couplings and water-gas shift will be emphasized along with the role of LDHs as catalysts, co-catalysts or catalytic precursors when it was clearly indicated. (LDHs properties metalsupport metal support route minireview, minireview mini review, review mini-review reactions photocatalysis electrocatalysis reduction carboncarbon carbon crosscouplings cross couplings watergas water gas catalysts cocatalysts co indicated

The composites of poly (butylene adipate co-terephthalate) / poly (lactic acid) (PBAT/PLA) blend and montmorillonites functionalized using imidazole-derived ionic liquids with different carbon chain sizes (butyl, octyl, and dodecyl) proved to be a promising alternative for improving the thermal and mechanical properties of the polymer blend. Functionalization of montmorillonites by ionic liquids was confirmed by increasing the basal spacing, and spectroscopical and thermal analysis evidence. The composite synthesis was carried out by casting technique generating homogeneous polymeric films. X-ray diffraction analyses suggested that montmorillonite functionalization with the ionic liquid of the butyl carbon chain fostered exfoliation and incorporation of the clay into the polymer. Furthermore, an increase in the thermal stability and mechanical properties of the material was observed. The other composites formed between the PBAT/PLA blend and the montmorillonite functionalized by ionic liquids of higher carbonic chain showed micro composites formation. Thus, their thermal and mechanical properties had no significant improvements. butylene coterephthalate co terephthalate co-terephthalate lactic acid PBATPLA PBAT PLA (PBAT/PLA imidazolederived imidazole derived butyl, (butyl octyl dodecyl spacing evidence films Xray X ray Furthermore observed formation Thus improvements

Resumen: En la actualidad, existen materiales provenientes de la industria, que bajo ciertas condiciones físicas pueden aportar al mejoramiento de las propiedades de mecánicas de un suelo. Materiales como el polvo de ladrillo (BD) y las cenizas de carbón (FA) tienen contenidos altos de SiO2 y Al3O2, que denotan actividad puzolánica. Además, se ha comprobado que dichos materiales pueden activarse al combinarse con cal. Esto genera procesos internos de cementación cuando el tamaño de grano es de 75 micras. Las vías rurales en Colombia presentan uno de los porcentajes más altos de toda la red vial y solo un 7% aproximadamente se encuentra en buen estado. Las difíciles condiciones de acceso, la susceptibilidad de los suelos, la imposibilidad financiera de intervenir toda esta red y la necesidad de implementar procesos de economía circular hace que estos materiales sean atractivos en temas de estabilización para mejorar las condiciones de tránsito. El BD y FA fueron aplicadas en dosificaciones del 0%, 3%, 6%, 9%, 12% y 24% en suelos finogranulares (limo y arcilla) y suelos arenosos, se evaluó la compactación y se realizó un diseño experimental factorial para evaluar la influencia del material en la variable resistencia a la compresión inconfinada, por medio de un análisis ANOVA. Para evaluar el desempeño del BD y las FA, se realizó una pista de prueba sobre una vía de bajo volumen de tráfico en el norte de Colombia, la cual tenía un suelo arenoso. BD y FA fueron adicionados al 12% y activados con cal, en celdas de 30 m de longitud. Para establecer un patrón comparativo se hicieron otras celdas en las mismas condiciones geométricas con materiales que usualmente se usan en este tipo de aplicaciones como el cemento. Estas celdas fueron evaluadas en periodo de 16 meses. Características como el módulo resiliente, El índice de internacional de rugosidad IRI y el coeficiente de resistencia al deslizamiento fueron medidos en ese período. Los resultados indican que cuando se adicionan estos materiales en suelos finogranulares (limos y arcillas), la resistencia a la compresión inconfinada aumenta un 150% respecto al suelo sin estabilizar, mientras que para suelos arenosos la resistencia aumenta desde un 70% hasta un 125%. Durante el período de evaluación, el BD y las FA lograron presentar aumentos por encima del 50% en el módulo resiliente respecto al suelo sin estabilizar. Sin embargo, las FA presentaron resultados comparables respecto al tramo estabilizado con cemento. Adicionalmente, sin bien, los tramos se fueron deteriorando en el tiempo, mantuvieron su indicen de rugosidad dentro de los rangos admisibles indicativos de buen índice de serviciabilidad.

Abstract: Currently, there are materials from industry that, under certain physical conditions, can contribute to the improvement of soils mechanical properties. Materials such as brick dust (BD) and fly ash (FA) have high SiO2 and Al2O3 contents, which denote pozzolanic activity. In addition, it has been shown that these materials can be activated when combined with lime. This generates internal cementation processes when the particle size is 0.075 mm. Rural roads in Colombia have one of the highest percentages of the entire road infrastructure, and only about 7% are in good condition. Difficult access conditions, soil susceptibility, the financial impossibility of intervening in this entire network and the need to implement circular economy processes, make these materials attractive in terms of stabilization to improve traffic conditions. BD and FA were applied in dosages of 0%, 3%, 6%, 9%, 12% and 24% in finogranular soils (silt and clay) and sandy soils, compaction was evaluated, and a factorial experimental design was carried out to evaluate the influence of the material on the variable unconfined compressive strength (UCS), through an ANOVA analysis. To evaluate the performance of BD and FA, a test track was made on a low traffic volume road in northern Colombia, which had a sandy soil. BD and FA were added at 12% and activated with lime, in 30 m long cells. To establish a comparative pattern, other cells were made in the same geometric conditions with materials that are usually used in this type of application, such as cement. These cells were evaluated over a period of 16 months. Characteristics such as resilient modulus, international roughness index (IRI) and slip resistance coefficient were measured during this period. The results indicate that when these materials are added to finogranular soils (silts and clays), the UCS increases by 150% with respect to the unstabilized soil, while for sandy soils the strength increases from 70% to 125%. During the evaluation period, the BD and the FA were able to increases of over 50% in the resilient modulus with respect to the unstabilized soil. However, the FA showed comparable results with respect to the cement-stabilized cell. In addition, although the sections deteriorated over time, they maintained their roughness index within the admissible ranges indicative of a good serviceability index.

ABSTRACT The city of Bahía Blanca, located in the southwest of the province of Buenos Aires, has sustained for several decades a strong process of territorial expansion towards urban peripheral sectors. The use of land in the east and southeast of the city is currently manifested as an important element in the urban structure, sometimes without an adequate geotechnical study to know their response to the loads they can bear when used as physical support for engineering structures. With the aim of characterizing and classifying the soils of the outcropping and subsoil units of the sector, standardized in situ tests were carried out: resistance to penetration to estimate the compactness of the soil in its natural state and density of the soil in situ by the cone of sand method. In the laboratory, the granulometry determination method was applied by wet sieving and the Atterberg limits were determined. Based on the established parameters, the Unified Soil Classification System (USCS) was carried out. The preliminary studies carried out allowed us to define that, in the study area, the soils vary in depth from fine soils, clays of medium to high plasticity and silts of low plasticity, which grade to clayey sands / silty sands. The soils studied are mainly made up of: soils type CH and Cl on the surface that grade to SC and

RESUMEN La ciudad de Bahía Blanca, ubicada en el sudoeste de la provincia de Buenos Aires, sostiene desde hace varias décadas un fuerte proceso de expansión territorial hacia sectores periféricos urbanos. El uso de las tierras en el este y sudeste de la ciudad, se manifiesta actualmente como un elemento importante en la estructura urbana, en ocasiones sin un adecuado estudio geotécnico para estudiar su respuesta ante las cargas que puedan soportar cuando son utilizados como soporte físico de estructuras ingenieriles. Con el objetivo de caracterizar y clasificar los suelos de las unidades aflorantes y del subsuelo del sector, se realizaron ensayos normalizados in situ: resistencia a la penetración para estimar la compacidad del suelo en estado natural y densidad del suelo in situ por el método de cono de arena. En laboratorio se aplicó método de determinación de la granulometría mediante tamizado por vía húmeda y se determinaron los límites de Atterberg. En función a los parámetros establecidos se realizó la Clasificación Unificada de Suelos (Unified Soil Classification System, USCS). Los estudios preliminares realizados permitieron definir que, en el área de estudio los suelos varían en profundidad desde suelos finos, arcillas de plasticidad media a alta y limos de baja plasticidad, que gradan a arenas arcillosas / arenas limosas. Los suelos estudiados están constituidos principalmente por: suelos tipo CH y Cl en superficie que gradan a SC y SM.

RESUMEN El estudio se centró en la influencia de la génesis geológica y el grado de cristalinidad en la cuantificación de fases minerales y contenido amorfo en arcillas cubanas. Se tomaron dos depósitos de arcilla con diferente génesis geológica y las muestras se caracterizaron mediante difracción de rayos X y técnicas de análisis de la fracción arcillosa. Se establecieron paragénesis dominantes para cada depósito, dominadas por caolinita, y se encontraron relaciones útiles entre diferencias estructurales y de tamaño de partículas con la génesis geológica, que pueden afectar una cuantificación adecuada. Se determinó que el nivel de meteorización condiciona el grado de cristalinidad, que a su vez tiene una fuerte relación con factores que inciden en una adecuada cuantificación. Finalmente, se establecen los elementos fundamentales para formular una metodología integral para la adecuada caracterización y cuantificación de las fases arcillosas.

ABSTRACT The study focused on the influence of geological genesis and degree of crystallinity on the quantification of mineral phases and amorphous content in Cuban clays. Two clay deposits with different geological genesis were taken and the samples were characterized using X-ray diffraction and techniques for analyzing the clay fraction. Dominant paragenesis were established for each deposit, dominated by kaolinite, and useful relationships were found between structural and particle size differences with geological genesis, which can affect proper quantification. It was determined that the level of weathering conditions the degree of crystallinity, which in turn has a strong relationship with factors that affect proper quantification. Finally, the fundamental elements for formulating a comprehensive methodology for the proper characterization and quantification of clay phases were established.

Abstract We present the results of ongoing research on different clay sources at Antofagasta de la Sierra, evaluating their potential for pottery-making. It included outcrops mapping, sample collection, petrographic characterisation and experimental archaeology to characterise different clay sources in Antofagasta de la Sierra. The former allowed locating and analysing clay components and the experimentation defined clay behaviour during pottery-making, both before and after firing. Our analyses established different categories based on clay appropriateness for pottery making: highly appropriate, slightly appropriate and non-appropriate clays. According to experimentation, this difference takes place after firing, as many highly-plastic and plastic clays disaggregate and peel off generating slightly hard and disaggregated fabrics due to the presence of small to large carbonate inclusions. These results provide a reference for archaeological studies of fabrics including the composition, granulometry and abundance of inclusions naturally present in local clays. In addition, data from experimental archaeology such as malleability and plasticity, contraction rate, thermal resistance and strength will help define the processes involved in pottery manufacture.

Resumen Presentamos los primeros resultados de una investigación, cuyo objetivo principal fue estudiar las diferentes fuentes de arcilla de Antofagasta de la Sierra y evaluar su potencialidad para la manufactura cerámica. A partir del mapeo de los distintos afloramientos, la toma de muestras, el análisis petrográfico y la arqueología experimental, se caracterizaron distintas fuentes de arcilla de Antofagasta de la Sierra. Los primeros estudios posibilitaron ubicar y analizar los componentes de las mismas y la experimentación permitió evaluar los comportamientos de las arcillas en los procesos de manufactura cerámica, antes y después de la cocción. Los análisis implementados permitieron establecer diferentes categorías en función de su adecuación a la producción cerámica: arcillas muy aptas, arcillas poco aptas y arcillas no aptas. Los resultados de la experimentación permitieron observar que esta diferencia tiene lugar luego del proceso de cocción, en el cual muchas de las arcillas que presentan una buena a muy buena plasticidad y maleabilidad, se disgregan y descascaran dando como resultado cerámicas con poca dureza y una textura disgregable debido, en todos los casos, a la presencia de inclusiones de carbonatos de tamaños medianos a grandes. Esta información resultará útil a la hora de abordar el estudio de la tecnología cerámica, al proporcionar datos de referencia para el análisis arqueológico, como la composición, la granulometría y la abundancia de los clastos presentes en las arcillas locales.

ABSTRACT Introduction: According to Barros (2017), Bentonite is a mixture of clays, generally impure, very fine grained, formed mainly by 60 to 80% of montmorillonite and also Kaolinite, Calcite and Pyrite. At the operational base of Petromoc Maputo Company, there is a set of tanks for fuel storage, that from a complex of tanks with coupled pipelines for the entry and withdrawal of fuels and effluent disposal. Objective: To evaluate the use of bentonite in the removal of toxic cations from the effluents generated at Petromoc Company. Materials and Methods: Bentonite samples were collected at the Industrial Minerals company. The effluent and influent samples were collected in the separator box of the operational base. The physicochemical experiments were carried out at the Analytical Chemistry Laboratory of the Eduardo Mondlane University. For the physical characterization of the bentonite, the pycnometric density, porosity (P) and specific surface area were determined. The mineralogical characterization was performed by X-ray diffraction analysis. The chemical characterization of the effluent and influent was performed by Inductively Coupled Plasma Atomic Emission Spectroscopy. Results and Discussion: Mineralogical characterization showed the presence of bentonite minerals. The pH of the effluent before interacting with the bentonite was 3.22, after interaction the pH is between 5.8 and 9. High concentrations of Cadmium (Cd), Chromium (Cr), Copper (Cu), Titanium (Ti) and Zinc (Zn) were determined in the effluent before the interaction with the bentonite. After the interaction, a removal of toxic elements is verified. Conclusions: The bentonite showed high efficiency in the removal of toxic cations.

RESUMEN Introducción: Según Barros (2017), la Bentonita es una mezcla de arcillas, generalmente impuras, de grano muy fino, formada principalmente por 60 a 80% de montmorillonita y también Caolinita, Calcita y Pirita. En la base operacional de la Empresa Petromoc Maputo, existe un conjunto de tanques para el almacenamiento de combustibles que forman un complejo de depósitos con tuberías acopladas para la entrada y retirada de combustibles y eliminación de efluentes. Objetivo: Evaluar el uso de la bentonita en la remoción de cationes tóxicos de los vertidos generados en la empresa Petromoc. Materiales y Métodos: La recogida de muestras de bentonita se realizó en la empresa de Minerales Industriales. Las muestras efluente y afluente se colectaron en la caja separadora de la base Operacional. Los experimentos fisicoquímicos se ejecutaron en el Laboratorio de Química Analítica de la Universidad Eduardo Mondlane. Para la caracterización física de la bentonita, se determinaron la densidad picnométrica, porosidad (P) y superficie específica. La caracterización mineralógica se realizó por análisis de difracción de rayos X. La caracterización química del efluente y afluente se realizó mediante la Espectroscopía de Emisión Atómica por Plasma Inductivamente acoplado. Resultados y Discusión: La caracterización mineralógica demostró la presencia de minerales de bentonita. El pH del efluente antes de interactuar con la bentonita era de 3,22, tras la interacción el pH está entre 5,8 a 9. Se determinaron altas concentraciones de Cadmio (Cd), Cromo (Cr), Cobre (Cu), Titanio (Ti) y Zinc (Zn), en el efluente antes de la interacción con la bentonita. Después de la interacción, se verifica remoción de elementos tóxicos. Conclusiones: La bentonita demostró alta eficiencia en la remoción de cationes tóxicos.

Abstract This keynote lecture discusses the results of a long lasting experimental research, devoted to the investigation of clay microstructure and its evolution upon loading. Micro-scale analyses, involving scanning electron microscopy, image processing, mercury intrusion porosimetry and swelling paths to test the clay bonding, are presented on clays subjected to different loading paths, with the purpose of providing experimental evidence of the processes at the micro-scale which underlie the clay response at the macro-scale. Data from the literature on clays of different classes, either soft or stiff, are compared to original results on two stiff clays, Pappadai and Lucera clay, both in their natural state and after reconstitution in the laboratory. The results presented herein allow building a conceptual model of the evolution of clay microstructure upon different loading paths, providing microstructural insights into the macro-behaviour described by constitutive laws and advising their mathematical formalization in the framework of either continuum mechanics or micro-mechanics. For editorial purposes, the research results are presented in two parts. The first part, presented in this paper, concerns the results for reconstituted clays, whereas a second part, concerning the corresponding natural clays, is discussed in a second companion paper. Microscale Micro scale analyses microscopy processing bonding microscale micro macroscale. macroscale macro scale. macro-scale classes laboratory macrobehaviour behaviour micromechanics. micromechanics mechanics. micro-mechanics purposes parts part paper

Abstract This paper reports the second part of the keynote lecture, whose part I has been already published in this journal, presenting extensive experimental research on the investigation of clay microstructure and its evolution upon loading. Whether the first part focused on the micro to macro behaviour of different reconstituted clays, this part instead concerns the microscale features of the corresponding natural clays, their changes under different loading paths and the ensuing constitutive modelling implications. The experimental investigation is carried out according to the methodology outlined in the part I-paper, hence micro-scale analyses are presented on natural clays subjected to macro-scale mechanical testing, with the purpose to provide experimental evidence of the processes at the micro-scale which underlie the clay response at the macro-scale. As for the reconstituted clays in the part I-paper, original results on stiff Pappadai and Lucera clay, this time in their natural state, are compared to literature results on clays of different classes, either soft or stiff. The results presented in this paper, together with those discussed in the part I, allow for a conceptual modelling of the microstructure evolution under compression of natural versus reconstituted multi-mineral clays, providing microstructural insights into the macro-behaviour described by constitutive laws and advising their mathematical formalization in the framework of either continuum mechanics or micro-mechanics. lecture journal implications Ipaper, Ipaper I-paper scale macroscale testing macroscale. scale. state classes multimineral multi mineral macrobehaviour micromechanics. micromechanics mechanics. micro-mechanics

Abstract To know the feasibility of alternative uses of sediments accumulated in La Esperanza dam, in the municipality of Guanajuato, they were subjected to quantitative chemical analysis. It was found that the contents of precious metals and rare earths make the economic exploitation of the sediments feasible. Additionally, the sediments, after sieved, were used to produce bricks. The results of compression, porosity, and adsorption tests were compared with those of bricks produced using clays from communities in the municipalities of Irapuato and Abasolo. No statistically significant differences were found in the results of the bricks produced with the three types of clays used; therefore, the sediments could be used to produce bricks. In this way, metals with high commercial value can be extracted from the sediments, and once processed they can be used to make bricks for the construction sector.

Resumen Con el propósito de conocer la factibilidad de usos alternativos de los sedimentos acumulados en la presa La Esperanza, en el municipio de Guanajuato, estos fueron sometidos a análisis químicos cuantitativos. Se encontró que los contenidos de metales preciosos y tierras raras hacen factible el aprovechamiento económico de los sedimentos. Adicionalmente, los sedimentos, una vez tamizados y clasificados, se usaron para producir ladrillos. Los resultados de pruebas de resistencia en compresión, porosidad y adsorción se compararon con los de ladrillos producidos usando arcillas de comunidades de los municipios de Irapuato y Abasolo. No se encontraron diferencias estadísticamente significativas en los resultados de los ladrillos producidos con los tres tipos de arcillas usadas; por lo tanto, los sedimentos podrían ser usados para producir ladrillos. De esta forma, de los sedimentos se pueden extraer metales con alto valor comercial, y una vez procesados se pueden usar para hacer ladrillos usables en construcción.

Abstract The potential of using calcined clay as supplementary cementitious material (SCM) stems from the global availability of clayey raw materials. The calcination dehydroxylates kaolinite and forms a reactive amorphous matrix. The kaolinite contained in the raw materials is a pre-indicator of the possible post-calcination reactivity. In the red ceramic industry, raw material is predominantly composed of clays and quartz. The sintered products discarded in this sector, called red ceramic waste (RCW), present, after comminution, the ability to react with lime depending on the kaolinite content contained in the raw material and its physical-chemical and mineralogical characteristics. In this work, the reactivity comparison was made of two samples of calcined clays from raw materials from different poles of ceramics, with varied kaolinite contents, with the respective RCWs. The reactivity tests were: modified Chapelle, Frattini, R³ test, and performance index (ID), with the variation of Portland cement type. The reactivity depends on the kaolinite content contained in the raw material and the BET specific surface area of the comminuted calcined material. The analysis of the results indicated little influence of the heat treatment on the reactivity of the calcined materials. SCM (SCM matrix preindicator pre indicator postcalcination post industry quartz sector RCW, RCW , (RCW) present comminution physicalchemical physical chemical characteristics work ceramics contents RCWs were Chapelle Frattini R test ID, ID (ID) type (RCW (ID

Resumo A potencialidade do uso de argila calcinada como material cimentício suplementar (MCS) decorre da disponibilidade global de matérias-primas argilosas. A calcinação desidroxila a caulinita e forma uma matriz amorfa reativa. O teor de caulinita nas matérias-primas é um pré-indicador da possível reatividade pós calcinação. Na indústria de cerâmica vermelha, a matéria-prima é composta predominantemente de argilominerais e quartzo. Os produtos sinterizados descartados nesse setor, denominados resíduo de cerâmica vermelha (RCV), apresentam, após cominuição, capacidade de reagir com cal a depender do teor de caulinita contido na matéria-prima e de suas características físico-químicas e mineralógicas. Neste trabalho foi realizada a comparação da reatividade de duas amostras de argilas calcinadas provenientes de matérias-primas de diferentes polos ceramistas, com distintos teores de caulinita, com os respectivos RCVs. Os ensaios dereatividade foram: Chapelle modificado, Frattini,teste R³ eíndice de desempenho (ID), com variação do tipo de cimento Portland. A reatividade foi dependente do teor de caulinita contido na matéria-prima e da área superficial específica BET do material calcinado cominuído. A análise dos resultados indicou pouca influência do tratamento térmico na reatividade dos materiais calcinados. MCS (MCS matériasprimas matérias primas argilosas reativa préindicador pré indicador matériaprima matéria prima quartzo setor RCV, RCV , (RCV) apresentam cominuição físicoquímicas físico químicas mineralógicas ceramistas RCVs foram modificado Frattiniteste Frattini teste R ID, ID (ID) Portland cominuído calcinados (RCV (ID

ABSTRACT The ANPCC currently contains the most extensive cave system in Argentina, with more than 5 kilometers extension represented by Arenal, Templo, Gendarme and Cabritos caverns. The structural stability of these is undeveloped and the motivation of this work is to contribute with studies to the subject. To achieve this particular aim, two specific susceptibility analysis methodologies in cave systems were used, applying both in caves of karstic or volcanic origin, developed in recent years: The Geotechnical Cave Index (Brandi et al., 2020) and the Q Index. adapted by Jordá-Bordehore (2017). Both classifications were applied to study a particular sector of the Arenal cave, leaving the rest of the cave system for future studies as required by the Ministry of Cultures of the province of Neuquén. The resulting zonification of the section studied was characterized based on these classifications, acquiring susceptibility to structural instability maps. Although each of the two classifications has been designed independently, the application of both showed us to compare their results and gain experience in the use of each of them, which will be a great contribution to decide how to continue the stability evaluation of the rest of the Cuchillo Curá Cave System. Based on the infield observations and the geotechnical studies carried out, it was determined that the Arenal cavern is contained in a poor to good (RMR) rock mass quality, affected by systematic discontinuities and, particularly, a clayey level that, due to its expansive, geometric and low resistance characteristics, it is considered as the most determining factor that influences its instability.

RESUMEN El ANPCC (Área Natural Protegida Cuchillo Curá) contiene actualmente al sistema cavernario más extenso de Argentina, con más de 5 kilómetros de extensión conformado por las cavernas Arenal, Templo, Gendarme y Cabritos. La estabilidad estructural de las mismas es poco conocida y es motivación de este trabajo aportar con estudios que desarrollen la temática. A tal fin, se emplearon dos metodologías específicas de análisis de susceptibilidad en sistemas cavernarios, aplicables tanto en cavernas de origen kárstico o volcánico: el Índice Geotécnico de Cavernas (Brandi et al., 2020) y el Índice Q adaptado por Jordá-Bordehore (2017). Ambas clasificaciones fueron aplicadas para estudiar particularmente un sector de la caverna Arenal, dejando el resto del sistema cavernario para próximos estudios en la medida que sea requerido por el Ministerio de las Culturas de la provincia del Neuquén. La resultante sectorización del tramo estudiado fue caracterizada en función de estas clasificaciones, ofreciendo mapas de susceptibilidad a la inestabilidad estructural. Si bien cada una de estas clasificaciones fue diseñada en forma independiente, la aplicación de ambas nos permitió comparar sus resultados y tomar experiencia en el uso de cada una de ellas, lo cual será un gran aporte para decidir cómo continuar la evaluación de estabilidad del resto del Sistema Cavernario Cuchillo Curá. En función de las observaciones en campo y los estudios geotécnicos desarrollados, se determinó que la caverna Arenal está contenida en un macizo rocoso de calidad mala a buena (RMR), afectada por discontinuidades sistemáticas y, particularmente, un nivel arcilloso que, por sus características expansivas, geométricas y de reducida resistencia, es considerado como el factor condicionante que más influye en la inestabilidad de la misma.

Abstract Heterogeneous catalysts, especially those produced with functionalized clays, can be used for methyl transesterification at moderate temperatures. The use of bentonite clay functionalized by potassium compounds (KF, KOH, K2CO3, KCl and K2SO4) in the methyl transesterification of cottonseed oil is the object of the present study. The catalysts were produced by contacting aqueous solutions with the clay and subsequent drying. The catalysts were characterized by Hammett indicators to determine alkalinity. The methyl transesterification reactions were made in a flask with stirring and reflux at 70°C for 2 h. The performance evaluation of the reaction was carried out using regression between the absorption band area and the concentration of a biodiesel-oil mixture by infrared spectroscopy. The catalytic activity is directly associated with the alkaline character of the catalysts. The catalysts produced with KCl and K2SO4 did not show conversion in the methyl transesterification reaction, while the catalysts produced with KF, KOH and K2CO3 showed a conversion greater than 90%. clays temperatures KF (KF KCO K CO KSO SO study drying alkalinity 70C C 70 h biodieseloil biodiesel spectroscopy K2SO K2CO 90 90% 7 9

Resumen (Introducción): el método más común para determinar el contenido de materia orgánica del suelo es el WalkleyBlack, pero este presenta desventajas medioambientales por el uso del tóxico dicromato de potasio; como alternativa, surge el método de pérdidas por ignición. Ambos métodos presentan resultados significativamente diferentes debido a que el método de ignición puede reportar datos mayores por la presencia de arcillas y por considerar todo el contenido orgánico de la muestra, a diferencia de Walkley-Black, que considera únicamente, los compuestos de cadenas más largas. (Objetivo): Se determinó la relación que existe entre el contenido de materia orgánica por Walkley-Black y perdidas por ignición considerando el contenido de arcilla. (Metodología): Se estudiaron 60 muestras de suelo del nororiente y centro de Honduras. El contenido de arcilla fue determinado a través del método de Bouyoucos. La materia orgánica se determinó por el método de Walkley-Black y por el método de ignición siguiendo lo establecido por los estándares internacionales de AASHTO T 194-97 (2018) y AASHTO T 267-86 (2013), respectivamente. (Resultados): Se encontró una relación lineal válida entre el contenido de materia orgánica determinado por Walkley-Black y por perdidas por ignición independiente del contenido de arcilla. Fue posible establecer un rango de interpretación del contenido de materia orgánica para el método de pérdidas por ignición a partir de los rangos de interpretación típicos reportados para el contenido de materia orgánica de WalkleyBlack. (Conclusiones): Los resultados de este estudio demostraron que es posible usar el método por ignición como alternativa al método Walkley-Black.

Abstract (Introduction): The most common method to determine the organic matter content of soil is the “Walkley-Black” method, but this method has environmental disadvantages due to the use of the toxic potassium dichromate. As an alternative, the loss on ignition method arises. Both present significantly different results because the ignition method can report higher data due to the presence of clays and because it considers all the organic content of the sample, unlike Walkley-Black method, which considers only the compounds with longer chains. (Objective): The relationship between the organic matter content determined by Walkley-Black and loss on ignition was determined considering the clay content. (Methodology): 60 soil samples from northeastern and central Honduras were studied. The clay content was determined through the Bouyoucos method. The organic matter content was determined by the Walkley-Black method and by the ignition method following the guidelines by the international standards AASHTO T 194-97 (2018) and AASHTO T 267-86 (2013), respectively. (Results): A valid linear relationship was found between the organic matter content determined by Walkley-Black and the loss on ignition regardless of the clay content. It was possible to establish an interpretation range for organic matter content for the loss on ignition method from the typical interpretation ranges reported for Walkley-Black organic matter content. (Conclusions): The results of this study showed that it is possible to use the ignition method as an alternative to Walkley-Black.

ABSTRACT The objective of the research is to know how Paraguayan clay crafts are disseminated in three cities and what are the main means used for their promotion or promotion on the internet from 2018 to 2022. The work was based on a quantitative cross-sectional approach and descriptive. The documentary analysis technique was used, reviewing websites, digital newspapers, blogs, social networks, etc., of the last five years. As a data collection instrument, a file with 6 dimensions and 24 criteria was used. A total of 44 publications were analyzed. The results refer that most of the publications mention the city of Areguá (64%), published mostly in 2020 (32%), through web pages (57%), the types of publication and predominant motives are articles. of promotion (48%), mentioning only 56% of the Guarani ancestral heritage. Therefore, it is concluded that greater support is needed in the dissemination and promotion of these crafts as cultural heritage inherited from the Guarani ancestors, so that they are not lost, as well as mechanisms that contribute to their appreciation and recognition, especially in the cities of Itá, Areguá and Tobatí.

RESUMEN La investigación tiene como objetivo determinar cómo se difunde las prácticas y saberes ancestrales de la cultura guaraní en las artesanías en barro de las ciudades de Itá, Areguá y Tobatí, desde el 2018 al 2022. Se basó en un enfoque cuantitativo de corte transversal y descriptivo. Se utilizó la técnica del análisis documental, revisando sitios web, periódicos digitales, blogs, redes sociales, etc., de los últimos cinco años. Como instrumento de recolección de datos se utilizó una ficha de 6 dimensiones y 24 criterios. Fueron analizadas un total de 44 publicaciones. Los resultados refieren que la mayoría de las publicaciones mencionan a la ciudad de Areguá (64%), publicadas en su mayoría en el 2020 (32%), mediante páginas webs (57%), los tipos de publicación y motivos predominante son los artículos de promoción (48%) haciendo mención solo el 56% a la herencia ancestral guaraní. Por lo que se concluye que necesario mayor apoyo en la difusión y promoción de estas artesanías como patrimonio cultural heredado de los ancestros guaraníes, para que no se pierdan, así como mecanismos que contribuyan a su valorización y reconocimiento, especialmente en las ciudades de Itá, Areguá y Tobatí.