Abstract Faced with the challenges posed by the need for fertilizers to maintain agricultural production, a biological process of atmospheric nitrogen fixation occurs naturally, which is carried out by a group of symbiotic bacteria that form a very close association with plants of the legume group, among which is the sweet clover (Melilotus spp.). From an ecological point of view, this plant has an essential function due to its good ability to associate with native nitrogen-fixing bacteria of the genus Sinorhizobium. A fundamental aspect is that this plant species can grow normally in alkaline soils, which doubles its importance since, on the one hand, it fixes nitrogen, and on the other hand, it can be incorporated as green manure. With this, the physicochemical properties of the soil are improved, and the levels of organic matter, which is in extremely poor condition in arid zone areas, are increased. Additionally, this species can withstand low temperatures and grow satisfactorily in winter. This paper presents a synthesis of the genus Melilotus and its symbiont Sinorhizobium meliloti and its importance as a potential natural soil improver.

Resumen Ante los retos por la necesidad de fertilizantes para mantener la producción agrícola, ocurre naturalmente un proceso biológico de fijación de nitrógeno atmosférico por parte de un grupo de bacterias simbióticas que forman una asociación muy estrecha con plantas del grupo de las leguminosas, entre las que se encuentran las alfalfillas o tréboles silvestres (Melilotus spp.). Desde el punto de vista ecológico esta planta tiene una función muy importante por la buena capacidad de asociarse a bacterias nativas del suelo fijadoras de nitrógeno del género Sinorhizobium. Un aspecto fundamental es que esta especie vegetal puede crecer normalmente en suelos alcalinos, lo que le convierte aún más como doble importante, ya que, por un lado, fija nitrógeno y por el otro puede incorporarse como abono verde. Con ello, se mejoran las propiedades físico-químicas del suelo y, se incrementan los niveles de materia orgánica, condición que es muy pobre en las áreas de zonas áridas. Adicionalmente, esta especie puede resistir bajas temperaturas y crecer satisfactoriamente en invierno. Este documento presenta una síntesis del género Melilotus y su simbionte Sinorhizobium meliloti, así como su importancia como posible mejorador natural del suelo.

Resumo Qualquer superfície sólida, desprotegida e indefesa no ambiente aquático será contaminada. A incrustação, por outro lado, pode afetar uma ampla gama de espécies que podem tolerar alguma epibiose. Vários outros, por outro lado, mantêm agressivamente os epibiontes fora de sua superfície corporal (anti-incrustante). As defesas anti-incrustantes são construídas em plantas marinhas como algas marinhas e ervas marinhas. Elas têm uma estrutura de superfície distinta com picos semelhantes a agulhas bem compactadas e coberturas anti-incrustantes, o que pode dificultar a capacidade de fixação das bactérias. A resistência química anti-incrustante é provavelmente uma reação biológica às desvantagens ecológicas da epibiose, especialmente para organismos capazes de realizar fotossíntese. O objetivo deste estudo foi verificar a eficácia dos compostos naturais derivados de algas marinhas do litoral na prevenção da incrustação. O mexilhão-marrom, importante organismo incrustante, foi avaliado em bioensaios de laboratório contra extratos orgânicos brutos de 51 populações, incluindo duas espécies de macroalgas. A atividade anti-incrustante exibiu um padrão filogenético distinto, com macroalgas vermelhas tendo a maior participação de espécies ativas, posteriormente macroalgas marrons. A ação anti-incrustante em algas verdes nunca foi significativa. Sete espécies apresentaram algum nível de defesa anti-incrustante induzida. Nossas descobertas parecem corroborar descobertas anteriores sobre a síntese de metabólitos secundários em algas marinhas, indicando que, na busca por novos anti-incrustantes, os pesquisadores devem concentrar seus esforços em macroalgas vermelhas tropicais.

Abstract Any solid, unprotected, and undefended surface in the aquatic environment will be fouled. Fouling, on the other hand, can affect a wide range of species that can tolerate some epibiosis. Several others, on the other hand, aggressively keep the epibionts off their body surface (antifouling). Antifouling defenses are built into marine plants like seaweed and seagrass. They do have a distinctive surface structure with tightly packed needle-like peaks and antifouling coverings, which may hinder settling bacteria's ability to cling. Chemical antifouling resistance is most probably a biological reaction to epibiosis' ecological drawbacks, especially for organisms capable of performing photosynthesis. The goal of this study was to see how effective natural compounds derived from littoral seaweeds were in preventing fouling. The brown mussel, an important fouling organism, was evaluated in laboratory bioassays against fifty-one populations' crude organic extracts including fort-two macroalgae species. Antifouling activity, exhibited a distinct phylogenetic pattern, with red macroalgae having the largest share of active species, subsequently brown macroalgae. Antifouling action in green seaweeds has never been significant. Seven species showed some level of induced antifouling defense. Our findings appear to back up previous findings about secondary metabolite synthesis in seaweeds, indicating that in the hunt for novel antifoulants, researchers should concentrate their efforts on tropical red macroalgae.

Abstract New natural reducing agents with a lower negative impact on the environment and with a high antimicrobial potential are required for the process of obtaining silver nanoparticles through the chemical reduction method. The use of plant extracts can be a fast track in the formation of nanoparticles. In this case, organic compounds such as terpenes, flavonoids, enzymes, proteins, and cofactors present in plants act as reducing agents for nanomaterials. This research evaluated the antimicrobial property of silver nanoparticles from extracts of Crescentia cujete L. The presence of quercetin (flavonoid) was determined by high-performance liquid chromatography (HPLC); the production of silver nanoparticles (AgNPs) was established by green synthesis; the size and morphology of the nanomaterials were evaluated by scanning electron microscope (SEM). The antimicrobial capacity was studied by two analysis methods: modified culture medium and surface seeding. The presence of quercetin (26.55 mg L-1) in the crude extract of Crescentia cujete L., identified by HPLC, was evidenced. Nanoparticle formation was spherical, with an average size of 250 ± 3 and 460 ± 6 nm. Microbiological cultures with treatment showed 94% microbial inhibition. It was concluded that the Crescentia cujete L., leaves shoed an acceptable concentration of quercetin to be used as a useful adjuvant to enhance the reduction of NPs synthesis. The nanoparticles produced by green synthesis proved to have a positive effect to combat pathogenic microorganisms.

Resumo Novos agentes redutores naturais com menor impacto negativo ao meio ambiente e com alto potencial antimicrobiano são necessários para o processo de obtenção de nanopartículas de prata, pelo método de redução química. O uso de extratos vegetais pode ser um caminho rápido na formação de nanopartículas. Nesse caso, compostos orgânicos como terpenos, flavonoides, enzimas, proteínas e cofatores presentes nas plantas atuam como agentes redutores dos nanomateriais. Esta pesquisa avaliou a propriedade antimicrobiana de nanopartículas de prata de extratos de Crescentia cujete L. A presença de quercetina (flavonoide) foi determinada por cromatografia líquida de alta eficiência (HPLC); a produção de nanopartículas de prata (AgNPs) foi estabelecida por síntese verde; o tamanho e a morfologia dos nanomateriais foram avaliadas dos por microscópio eletrônico de varredura (SEM). A capacidade antimicrobiana foi estudada por dois métodos de análise: meio de cultura modificado e semeadura em superfície. Foi evidenciada a presença de quercetina (26,55 mg L-1) no extrato bruto de Crescentia cujete L., identificada por HPLC. A formação das nanopartículas foi esférica, com tamanho médio de 250 ± 3 e 460 ± 6 nm. Culturas microbiológicas com tratamento mostraram 94% de inibição microbiana. Assim, concluiu-se que as folhas de Crescentia cujete L. apresentam uma concentração aceitável de quercetina para ser utilizada como um adjuvante útil para potencializar a redução da síntese de NPs. As nanopartículas produzidas pela síntese verde provaram ter um efeito positivo no combate a microrganismos patogênicos.

RESUMEN El presente trabajo tiene la finalidad de dar a conocer el desarrollo de un prototipo de sensor para la medición de mercurio (Hg2+) en solución acuosa sobre una plataforma electroquímica basada en electrodos serigrafiados de nanotubos de carbonos (CNT-SPE) en conjunto con nanopartículas de oro (NPs-Au) realizadas a través de síntesis verde, utilizando extracto acuoso de Sargassum spp. Para esto, se realizó la caracterización de las NPs-Au por espectroscopía ultravioleta-visible (UV-Vis), infrarrojo (TF-IR), difracción de rayos X (DRX) y microscopía electrónica de barrido (SEM); obteniendo nanopartículas entre 80-100 nm las cuales poseen un recubrimiento orgánico que les confiere una sinergia al momento de ser conjugadas con CNT-SPE oxidadas/activadas. Posteriormente, las NPs-Au se utilizaron para modificar el CNT-SPE a través del método drop-casting y así ensamblar un novedoso sensor electroquímico para la medición de Hg2+, cuya validación y habilidad para medir fue demostrada utilizando voltametría diferencial de pulso (DPV). Se obtuvieron límites de detección de 2.38 𝜇M y cuantificación de 3 𝜇M. Los resultados demuestran que la plataforma desarrollada es una alternativa, rápida, eficiente y portátil para la medición de Hg2+.

ABSTRACT The present manuscript’s objective is to develop a sensor prototype for measuring mercury (Hg2+) in an aqueous solution. An electrochemical platform based on screen-printed carbon nanotube electrodes (CNT-SPE) and gold nanoparticles (NPs-Au) synthesized using a green synthesis method with an aqueous extract of Sargassum spp. For this, the characterization of the NPs-Au was carried out by ultraviolet-visible (UV-Vis), infrared (TF-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) spectroscopy. The nanoparticles have sizes between 80-100 nm and an organic coating that allows them a synergy when conjugated with oxidized/activated CNT-SPE. Subsequently, the NPs-Au were used to modify the CNT-SPE through the drop-casting method and thus assemble a novel electrochemical sensor for the measurement of Hg2+, whose validation and ability to measure was demonstrated using differential pulse voltammetry (DPV). Detection limits of 2.38 𝜇M and quantification of 3 𝜇M were obtained. The results show that the developed platform is a fast, efficient and portable alternative for the measurement of Hg2+.

Resumen Emile-Eugène Burcker (1846-1908) fue un farmacéutico militar francés que llevó a cabo un exitoso programa de investigación sobre la aplicación del método Friedel-Crafts a la síntesis de ácidos, cetonas, aldehídos y glicoles en la serie aromática, que finalmente culminó en su tesis doctoral. En particular, fue capaz de sintetizar un número significativo de nuevos ácidos acetónicos y cetónicos caracterizados. por la presencia en su molécula tanto del grupo carbonilo CO como del grupo COOH; teniendo así la capacidad de reaccionar como acetonas, formando sales, ésteres, así como ácidos ordinarios, y todo también, bajo la influencia del hidrógeno naciente, de formar oxácidos o ácido-alcoholes. Algunos de los nuevos compuestos incluían el ácido benzoilpropiónico, ácido benzhidrilpropiónico, fenil propil acetona, ácido toluilpropiónico, ácido fenilcanfórico, etc. Burcker también estableció el mejor procedimiento para dosificar KOH, así como una versión mejorada del método Kjeldahl para determinar la cantidad de nitrógeno presente en compuestos orgánicos.

Abstract Emile-Eugène Burcker (1846-1908) was a French military pharmacist who carried out a successful research program on the application of the FriedelCrafts method to the synthesis of acids, ketones, aldehydes, and glycols in the aromatic series, which finally culminated in his doctoral thesis. In particular, he was able to synthesize a significant number of new acetonic and ketonic acids characterized by the presence in their molecule of both the carbonyl group CO and the group COOH; thus, having the ability to react as ketones, forming salts, esters, and as ordinary acids, and everything also, under the influence of nascent hydrogen, of forming oxyacids or acid-alcohols. Some new compounds included benzoylpropionic acid, benzhydrylpropionic acid, phenyl propyl acetone, toluylpropionic acid, phenylcamphoric acid, etc. Burcker also established the best procedure for dosing KOH, as well as an improved version of the Kjeldahl method to determine the amount of nitrogen present in organic compounds.

Resumen Conocido originalmente por sus efectos deletéreos en la salud, recientemente se ha reconocido al sulfuro de hidrógeno (H2S) como un gasotransmisor de importancia biológica, al igual que el óxido nítrico y el monóxido de carbono. El H2S puede producirse de forma endógena en las células de mamíferos por dos vías: la vía enzimática y la vía no enzimática. Cuando se produce por la vía enzimática, su síntesis se lleva a cabo a partir de los aminoácidos L-cisteína o metionina mediante transulfuración y transmetilación. También se puede producir el H2S a partir donadores de grupos sulfuro como, por ejemplo, compuestos orgánicos que se encuentran presentes en algunos vegetales. Actualmente es bien conocido el papel del H2S como protector a nivel cerebral y cardiaco, y cada vez adquiere mayor relevancia su estudio como coadyuvante terapéutico en padecimientos metabólicos como la obesidad y la diabetes mellitus de tipo 2. El objetivo de esta revisión es examinar cómo impacta el aporte de donadores y precursores del sulfuro de hidrógeno por la dieta en la salud y la enfermedad.

Abstract Initially known for its deleterious health effects, hydrogen sulfide (H2S) has recently been recognized as a biologically important gas carrier, like nitric oxide and carbon monoxide. H2S is produced endogenously in mammalian cells by enzymatic and non-enzymatic pathways. When it is produced by the enzymatic pathway, its synthesis is carried out from the amino acid L-cysteine through the transsulfuration pathway. It can also be produced endogenously from exogenous compounds that function as H2S donors as, for example, the naturally occurring organic donors found in some plants. Currently, the role of H2S is well known as brain and cardiac protector, and its research as a therapeutic adjuvant in metabolic diseases such as obesity and type-2 diabetes is becoming increasingly important. The objective of this review is to examine how the contribution of donors and precursors of hydrogen sulfide by the diet impacts health and disease.

RESUMEN Presentamos aquí una síntesis del registro arqueológico del alero Los Viscos, sitio destacado por la buena preservación del material orgánico, y lo analizamos en relación con los estudios paleoambientales desarrollados en el valle de El Bolsón, un valle de altura en Catamarca, Argentina, y los paisajes sociales inferidos para el área. El alero Los Viscos estuvo ocupado a lo largo de los últimos 1200 años, desde tiempos Formativos. El material allí recuperado presenta evidencia de estrategias mixtas de producción y obtención de una gran diversidad de recursos. La intensificación en su explotación desde el Período de Desarrollos Regionales sugiere nuevos condicionantes. Este registro representa un período en el que la evidencia paleoambiental sugiere cambios en la morfodinámica del área que impidieron la preservación de otros sitios contempo ráneos. Así, Los Viscos posibilita conocer con mayor resolución las prácticas de producción y consumo en el valle durante los dos últimos milenios.

ABSTRACT We present a synthesis of the archaeological record at Los Viscos site, with an outstanding preservation of organic material, and analyze it in relation to the paleoenvironmental studies developed in El Bolsón valley, a high-altitude valley in Catamarca, Argentina, and the social landscapes inferred for the area. Los Viscos rock shelter has been occupied for the last 1200 years since Formative times. The material recovered there includes evidence of mixed production and resource procurement strategies over a great diversity of resources. Intensification in resource exploitation since the Regional Developments Period suggests novel constraints at the time. This record represents a period in which the palaeoenvironmental evidence suggests changes in the regional morphodynamics that prevented the preservation of other contemporary sites. Thus, Los Viscos provides a better understanding of production and consumption practices in the valley over the last two millennia.

Resumen La educación popular barrial para la acción ambiental en las áreas protegidas municipales en la ciudad de La Paz no debe ser entendida como un campo de estudio sino como un proceso de educación ambiental; por ello, el presente estudio aporta como una herramienta de diagnóstico y un plan de trabajo para múltiples sujetos que viven en la ciudad. Las áreas protegidas municipales son poco conocidas; sin embargo, existe un importante movimiento de instituciones y activistas que promueven su defensa, teniendo una demanda de construir conocimientos de educación ambiental en la práctica de la enseñanza superior, así como en la vida orgánica de varias juntas de vecinos. Se utilizó la metodología de la Investigación Acción Participativa, con un enfoque cualitativo, desde el paradigma sociocrítico, se aplicó el método de investigación de análisis, síntesis y el comparativo. La técnica utilizada fue el grupo focal con participantes de estamentos universitarios, docentes, dirigentes vecinales, funcionarios municipales y activistas medioambientales urbanos. Fueron tres los objetivos específicos y once indicadores. El estudio establece el estatus y beneficios de las áreas protegidas municipales a partir de la información, percepción y formación ambiental; los sujetos detallan los componentes de la acción ambiental que contrarresten las vulnerabilidades en contra de las áreas protegidas municipales conociendo las normas, la responsabilidad ambiental, el compromiso moral, las acciones a favor o la indiferencia. También los participantes hablan de los procesos de educación popular barrial necesarios para una efectiva acción ambiental que contrarresten las vulnerabilidades en contra de las áreas protegidas municipales.

Abstract Popular neighborhood education for environmental action in municipal protected areas in the city of La Paz should not be understood as a field of study but as a process of environmental education; therefore, the present study contributes as a diagnostic tool and a work plan for multiple subjects living in the city. The municipal protected areas are little known; however, there is an important movement of institutions and activists that promote their defense, demanding to build knowledge of environmental education in the practice of higher education as well as in the organic life of several neighborhood councils. The methodology of Participatory Action Research was used, with a qualitative approach, from the sociocritical paradigm, the research method of analysis, synthesis and comparative was applied. The technique used was the focus group with participants from universities, teachers, neighborhood leaders, municipal officials and urban environmental activists. There were three specific objectives and eleven indicators. The study establishes the status and benefits of municipal protected areas based on information, perception and environmental education; the subjects detail the components of environmental action that counteract the vulnerabilities of municipal protected areas, knowing the norms, environmental responsibility, moral commitment, actions in favor or indifference. The participants also talk about the neighborhood popular education processes necessary for an effective environmental action to counteract the vulnerabilities of municipal protected areas.

Resumen: En este trabajo se desarrolló un nanomaterial a base de una estructura de hidróxido doble laminar HDL (ZnAl) impregnado de moléculas orgánicas de timol; se estudió el efecto fungistático in vitro e in vivo ante dos hongos fitopatógenos Colletotrichum gloeosporioides y Botrytis cinerea causantes de enfermedades en plantas como la antracnosis y el moho gris. La síntesis de este nanomaterial se llevó a cabo por el método de reconstrucción del óxido mixto ZnAl-(O) pasando por una combustión; la caracterización fisicoquímica del material se efectuó por difracción de rayos-X XRD, análisis termogravimétrico TGA, espectroscopía infrarroja por transformada de Fourier FTIR y microscopía electrónica de barrido MEB. Se realizó un análisis de conservación de la molécula orgánica timol en presencia del hongo fitopatógeno B. cinerea y sin la acción bioquímica de este, mediante cromatografía líquida de alta eficacia HPLC. Concluyendo que el nanomaterial híbrido sintetizado HDL-T puede ser una alternativa para mitigar problemas agrícolas derivado de hongos fitopatógenos sin dañar el medio ambiente y evitando problemas sanitarios; esto por la protección que el HDL le brinda al timol retardando así su descomposición y haciéndole mucho más manejable.

Abstract: In this work, a nanomaterial was developed based on a structure of double laminar hydroxide DLH (ZnAl) impregnated with organic molecules of thymol; the fungistatic effect was studied in vitro and in vivo against two phytopathogenic fungi Colletotrichum gloeosporioides and Botrytis cinerea causing diseases in orchards such as anthracnose and gray mold. The synthesis of this nanomaterial was carried out by the method of reconstruction of the mixed oxide ZnAl-(O) through a combustion; the physicochemical characterization of the material was carried out by X-ray diffraction XRD, thermogravimetric analysis TGA, infrared spectroscopy by Fourier transforms FTIR and scanning electron microscopy SEM. A conservation analysis of the organic molecule thymol was carried out in the presence of the phytopathogenic fungus B. cinerea and without the biochemical action of this, by means of high efficacy liquid chromatography HPLC. Concluding that the hybrid nanomaterial synthesized DLH-T can be a great alternative to mitigate agricultural problems derived from phytopathogenic fungi without damaging the environment and avoiding sanitary problems; this by the protection that DLH provides to thymol thus delaying its decomposition and making it much more manageable.

Sustainable and environmentally friendly methods for nanomaterials synthesis have been emerging recently. The use of extracts of polyphenol-rich plants with high reducing and chelating power is advantageous because the polyphenol can protect the nanomaterial from agglomeration and deactivation. Green nanomaterials have been applied in several areas, including remediation of toxic organic pollutants from contaminated effluents. Herein, we describe the preparation of green iron oxide nanoparticles (IONPs) with extracts of the plant Camellia sinensis as black tea for dye removal application. The as-prepared IONPs were composed of amorphous FeOOH and FeII/III-polyphenol complexes. To obtain crystalline and pure iron-based nanomaterials, the amorphous precursor was annealed at 900 ºC. Samples of black tea from different regions were used to verify the reproducibility of the iron phases formed. The same iron phases were obtained for all black tea samples, α-Fe2O3 (hematite), FePO4, and Fe3PO7, but in different proportions. The materials were applied as heterogeneous-Fenton catalysts for the removal of the dye methyl orange. The amorphous as-prepared IONPs were more active than the respective annealed IONPs due to the proton release from the polyphenol into the reaction medium, setting the pH to around 3, which is the optimum pH for the Fenton system.

ABSTRACT In this work, the physicochemical characterization of the distillery stillage from the UEB “Arquímedes Colina” was carried out. The parameters that determine the pollutant load of the residual were evaluated, such as pH, electrical conductivity, temperature and ash. Also, due to the intended use of this residual, the content of reducing sugars, fixed carbon and elemental and immediate analysis were evaluated. The results obtained indicate that according to Cuban Standard 27: 2012 the residual has a high pollutant load due mainly to its low pH (4,4), high temperature (99 oC) and high content of dissolved solids (40,10 g/L). The reductant content and Pol are 0,20 % and 0,12 %, respectively; indicating a low sugar content in the liquid residual. Fixed carbon is 6,5 g/L indicating that the organic matter present is relatively volatile.

RESUMEN En este trabajo se realizó la caracterización físico-química de la vinaza de destilería de la UEB “Arquímedes Colina”. Se evaluaron los parámetros que determinan la carga contaminante del residual, como es el caso del pH, conductividad eléctrica, temperatura y cenizas. También, por la utilidad que se le pretende dar a este residual, se evaluó el contenido de azucares reductores, carbón fijo y análisis elemental e inmediato. Los resultados obtenidos indican que, según la Norma Cubana 27:2012, el residual posee una alta carga contaminante debido, fundamentalmente, a su bajo pH (4,4), su alta temperatura (99oC) y al elevado contenido de sólidos disueltos (40,10 g/L). El contenido de reductores y la polarización (Pol) son 0,20 %y 0,12 %, respectivamente, lo que indica un contenido bajo de azúcares en el residual líquido. El carbón fijo es 6,5 g/L; esto demuestra que la materia orgánica presente es relativamente volátil.

Fingermark dusting powders are an important tool of forensic practitioners, being a first-choice process for most crime scene investigators. The development of new products is of utmost importance for forensic science. Hydrazones comprise compounds derived from ketones or aldehydes in reaction with hydrazines. These reactions are widely studied in organic chemistry because of the versatility of these compounds in organic synthesis. The study of these reactions leads to the understanding of the nucleophilicity of hydrazines, as well as the electrophilicity of aldehydes and ketones. The present work presents one proposal of experimental organic chemistry, aiming at a new application of this classic class of organic substances in forensic chemistry, specifically as a developer of latent fingermarks due to the variations of the color of the compounds, with spectra ranging in a range from 250 to 500 nm. These compounds were identified by Infrared Spectroscopy, Ultraviolet-Visible Spectroscopy and Mass Spectrometry. The development on glass surfaces demonstrated the potential application of these compounds in everyday life situations.

The negative health and socio-economic impacts of emissions associated with domestic fuel burning are widely recognized. Although there has been much progress in the provision of electricity to households in South Africa, many still rely on solid fuel sources such as wood and coal. While various investigations have been done on reducing household emissions by reducing the use of polluting fuels and improvements in combustion efficiency, comparatively fewer studies have been conducted on the reduction of emissions through use of abatement technology. Catalytic oxidation could be utilized to oxidize particulate matter precursors such as volatile organic compounds and soot particles to reduce secondary particulate formation. Although catalytic methods have not been effectively utilized in practical domestic applications, studies have shown effective soot reduction during laboratory testing. This study investigated the synthesis and use of a manganese oxide based catalyst to reduce particulate matter from domestic fuel burning stoves. The catalyst was synthesized onto a mesh substrate and inserted into the flue of the stove. During field testing, the presence of the catalyst increased the mass of particulate matter collected onto PTFE filters used for gravimetric analysis, with Scanning Electron Microscopy (SEM) analysis showing spherical particles in the pores of the filters used during the catalytic runs. The baseline runs had very few of these particle clusters. Energy Dispersive X-Ray (EDX) analysis of the catalyst run filters did not detect manganese, revealing that increased particulate concentrations were not as a result of macroscopic particles of the catalyst being dislodged from the support. Dislodgement of very small metal particles from the catalyst could, however serve as nucleation nodes for particle growth which would have a non-metal coating leading to the non-detection of manganese. The increase in particulate matter could also be caused by the impingement of particulate matter precursors on the catalyst followed by particle growth and dislodgement into the flue gas. The testwork showed that an active catalyst can be synthesized onto a mesh catalyst support in a relatively simple and cost-effective manner, which can be utilized in domestic fuel burning devices. It is recommended that a range of optimized, potentially active catalysts be tested to improve the oxidation of particulate matter precursors to carbon dioxide.

Resumen Pierre Oscar Figuier (1759-1817), farmacéutico francés cuya principal contribución fue el descubrimiento del uso de carbón vegetal para blanquear sustancias inorgánicas y orgánicas. Figuier también realizó un trabajo sustancial sobre la química del oro, la síntesis de muchos de sus compuestos, particularmente una sal triple de cloruro de oro y cloruro de sodio. Determinó la composición de los garbanzos y del cardo estrellado.

Abstract Pierre Oscar Figuier (1759-1817), a French pharmacist whose main contribution was the discovery of using animal charcoal for bleaching inorganic and organic substances. Figuier also carried substantial work on the chemistry of gold, the synthesis of many of its compounds, particularly a triple salt of gold chloride and sodium chloride. He determined the composition of purple thistle and chickpeas.

Resumen Las 2,2’:6’,2’’-terpiridinas se consideran precursores versátiles para la obtención de complejos metálicos con gran uso en importantes aplicaciones, tanto en ciencia básica como aplicada, razón por lo cual deben explorarse metodologías de síntesis con rutas alternativas que, al ser comparadas con las tradicionales, se destaquen por presentar mejores resultados y con un mayor impacto en nuestro entorno. La apropiación de estas alternativas, junto con el cumplimiento de un diseño experimental bien planeado, permitirá trascender en la formación de nuestros estudiantes en conceptos de síntesis orgánica con un enfoque enmarcado dentro de la química verde. En esta investigación, se describe el uso de la reacción de Kröhnke, como estrategia modelo para evaluar la conveniencia de un diseño experimental 3x2 enfocado en la obtención de una serie de 4’-aril-2,2’:6’,2’’-terpiridinas, mediante calentamiento por irradiación microondas. Para lo cual se desarrolla una secuencia didáctica como método de enseñanza-aprendizaje en el laboratorio para que estudiantes de química y ciencias afines, puedan desarrollar un diseño experimental en diferentes contextos, por medio de una metodología guiada paso a paso, con la cual se logren los objetivos de aprendizaje esperados. De este modo, se estudiaron los parámetros, potencia de microondas y tiempo de irradiación, como variables determinantes en el proceso y en los rendimientos de reacción. La caracterización de los compuestos obtenidos se realizó a través de técnicas espectroscópicas y espectrofotométricas.

Abstract The 2,2’:6’,2’’-terpirydines are considered versatile precursors for obtaining metal complexes widely used in important applications, both in basic and applied science. For this reason, synthetic methodologies with alternative routes should be explored that, when compared with traditional ones, stand out for presenting better results and with a greater impact on our environment. The appropriation of these alternatives, together with the fulfillment of a well-planned experimental design, will allow us to transcend the training of our students in concepts of organic synthesis with an approach framed within green chemistry. In this research, the use of the Kröhnke reaction is described as a model strategy to evaluate the suitability of a 3x2 experimental design focused on obtaining a series of 4’-aryl-2,2’:6’,2’’-terpyridines, by microwave irradiation heating. For which a didactic sequence is proposed as a teaching-learning method in the laboratory, so that chemistry and related sciences students can carry out an experimental design in various contexts, through a step-by-step guided methodology, in which the expected learning objectives are achieved. The parameters, microwave power and irradiation time, were studied as determining variables in the process and the reaction yields. The characterization of the compounds was carried out through the measurement of their physical properties, spectroscopic and spectrophotometric techniques.