Obtención de hidrolizado de aceite de macauba y su aplicación en la producción de ésteres metílicos

This work aimed to obtain a hydrolyzate rich in free fatty acids (FFA) from the hydrolysis of macauba oil for subsequent esterification and obtaining of methyl esters. To determine the conditions that maximize FFA yield in the hydrolysis step, the effects of buffer solution percentage and catalyst concentration (Lipozyme® RM IM) were determined at 55 ºC and 6 h. From the results, it was verified that both variables evaluated in the experimental range had an influence on the reaction and their increase favored the production of FFA. Additional experiments were carried out to assess the influence of reaction time with a progressive increase up to 8 h. Hydrolyzate with ~92 wt % FFA was obtained and its use in the enzymatic esterification step using Novozym® 435 as catalyst resulted in ~95 % FFA conversion. Regarding the reuse of enzymes at each stage, a ~50 % reduction in FFA yield was found and only 98 % FFA conversion.Este trabajo tuvo como objetivo obtener un hidrolizado rico en ácidos grasos libres (AGL) a partir de la hidrólisis del aceite de frutos de macauba, para su posterior esterificación y obtención de ésteres metílicos. Para determinar las condiciones que maximizan el rendimiento de AGL en la etapa de hidrólisis, se determinaron los efectos del porcentaje de solución amortiguadora y la concentración de catalizador (Lipozyme® RM IM) a 55 ºC y 6 h. De los resultados se verificó que ambas variables, en el rango experimental evaluado, tienen influencia en la reacción y su incremento favorece la producción de AGL. Se llevaron a cabo experimentos adicionales para evaluar la influencia del tiempo de reacción, observándose un aumento progresivo hasta las 8 h. Se obtuvo un hidrolizado con ~92 % en peso de FFA y su uso en el paso de esterificación enzimática, usando Novozym® 435 como catalizador, resultó en ~95 % de conversión de FFA. Al investigar la reutilización de enzimas, en cada etapa, se encontró una reducción de ~50 % en el rendimiento de FFA y solo un 98 % en la conversión de FFA

Estudio de las condiciones para la producción de ésteres etílicos utilizando aceite de fritura desechado y catalizador KF/arcilla en un sistema continuo

The transesterification of residual frying oil (RFO) with pressurized ethanol was carried out in a continuous reactor containing KF/clay as a heterogeneous catalyst. In the experiments, different oil:ethanol mass ratios were evaluated at 275 and 300 ºC and 20 MPa. In the sequence, the operational stability of the catalyst was evaluated for 8 hours, as well as the conduct of the reaction in two steps (testing new and recycled catalyst). An esters yield of ~90% was achieve at 275 ºC, for15 min and at 1:1.5 oil:ethanol mass ratio. Under these conditions, the catalyst provided a stable yield in the first 3 hours of operation, and a total decrease of 29% after 8 hours. This result can be attributed mainly to the leaching of the K+ cations for the reactions in which the catalyst was exposed to long operating times. The two-step reaction served to increase the RFO conversion to esters, with low thermal decomposition.La transesterificación de aceite de fritura desechado (AFD) con etanol presurizado se llevó a cabo en un reactor continuo que contenía KF/arcilla como catalizador heterogéneo. En los experimentos, se evaluaron diferentes relaciones de cantidad de aceite:etanol a 275 y 300 ºC y 20 MPa. En la secuencia, se evaluó la estabilidad operativa del catalizador durante 8 horas, así como la conducta de la reacción en dos pasos (prueba de catalizador nuevo y reciclado). Se logró un rendimiento de ésteres de ~ 90% a 275 ºC, 15 min y una relación de aceite:etanol de 1:1,5. En estas condiciones, el catalizador proporcionó un rendimiento estable en las primeras 3 horas de funcionamiento y una disminución total del 29% después de 8 horas. Este resultado se puede atribuir principalmente a la lixiviación de los cationes K+ para las reacciones en las que el catalizador estuvo expuesto durante las condiciones de funcionamiento. La reacción de dos pasos permitió aumentar la conversión de AFD a ésteres, con baja descomposición térmica

Aceite de semilla de maracuyá: extracción y posterior reacción de transesterificación

This work aims to remove the oil from passion fruit seeds using ethanol as solvent and then to carry out the transesterification of the product from the extraction step (oil + ethanol). The effects of operational variables in the ultrasound-assisted extraction (UAE) were evaluated and traditional extraction was performed for comparison. The extraction product was directed to the reaction step using an enzymatic catalyst. UAE provided oil yield from 12.32 to 21.76%, and the maximum value (73.7% of the traditional extraction yield) was obtained at 60 °C and 50 min using a solvent-to-seed ratio of 4. Oil removal was favored by increases in the investigated variables. g-tocopherol, δ-tocopherol and a high concentration of polyunsaturated fatty acids were identified in the oils. The oil obtained by UAE presented higher phytosterol contents. From the reaction step, samples were obtained with higher concentrations of ethyl esters, in addition to emulsifiers (diglycerides and monoglycerides).Este trabajo tiene como objetivo la extracción del aceite de la semilla de maracuyá utilizando etanol como disolvente y posteriormente llevar a cabo la transesterificación del producto obtenido (aceite + etanol). Se evaluaron los efectos de las variables operativas en la extracción asistida por ultrasonido (EAU) y se realizó la extracción clásica a efectos comparativos. El producto de extracción se dirigió a la etapa de reacción usando catalizador enzimático. EAU proporcionó un rendimiento de aceite de 12,32 a 21,76%, y el valor máximo (73,7% del rendimiento de extracción clásico) se obtuvo a 60 °C durante 50 min usando una relación de solvente a semilla de 4. La extracción de aceite se favorece con el aumento de las variables investigadas. Se identificaron en los aceites g- y δ-tocoferol y una alta concentración de ácidos grasos poliinsaturados. El aceite obtenido por los EAU presentó un mayor contenido de fitosteroles. De la etapa de reacción, se obtuvieron muestras con concentraciones más altas de ésteres etílicos, además de emulsionantes (diglicéridos y monoglicéridos)

Evaluación de la obtención de aceite de girasol a partir de extracción acuosa enzimática usando enzimas proteasa

The aim of this work was to maximize the enzymatic aqueous extraction (EAE) of sunflower seed oil using protease enzymes from the evaluation of various temperatures, pH and enzyme concentrations, using a Box-Behnken experimental design. The effect of a thermal pre-treatment of sunflower seeds on free oil yield (FOY) and oil quality was also determined. In the experimental range adopted, a lower temperature (40 °C) provided higher FOY values, as well as the intermediate pH (8.00) and maximum enzyme concentration (9% v/v). Thermal pre-treatment provided an increase in FOY in the initial extraction times (60 to 180 min) and decreased of the extraction time of 4 to 3 h to obtain the highest FOY value (~16%). The fatty acid composition of the oils obtained showed a predominance of oleic (~47.5%) and linoleic acids (~39.5%). The total phytosterol content in the samples was hardly affected by the heat pre-treatment of the seeds, while the fatty acid profile, tocopherol content and oxidative stability were not altered.El objetivo de este trabajo fue maximizar la extracción acuosa enzimática (EAE) de aceite de semillas de girasol utilizando la enzima proteasa a partir de la evaluación de las variables temperatura, pH y concentración de la enzima, utilizando un diseño experimental de Box-Behnken. Además, se determinó el efecto del pretratamiento térmico de las semillas de girasol sobre el rendimiento (RA) y la calidad del aceite. En el rango experimental adoptado, las temperaturas más bajas (40 °C) proporcionaron valores de RA más altos, así como el pH intermedio (8,00) y la concentración máxima de enzima (9% v/v). El pretratamiento térmico proporcionó un aumento del RA en los tiempos de extracción iniciales (60 a 180 min) y una disminución del tiempo de extracción de 4 a 3 h para obtener el valor de RA más alto (~ 16%). La composición en ácidos grasos de los aceites obtenidos mostró predominio de los ácidos oleico (~47,5%) y linoleico (~39,5%). El contenido total de fitosteroles en las muestras se vio poco afectado por el pretratamiento térmico de las semillas, mientras que el perfil de ácidos grasos, el contenido de tocoferoles y la estabilidad oxidativa no se vieron afectados

Interventions in overcrowding of emergency departments: an overview of systematic reviews

OBJECTIVE: To present an overview of systematic reviews on throughput interventions to solve the overcrowding of emergency departments. METHODS: Electronic searches for reviews published between 2007 and 2018 were made on PubMed, Cochrane Library, EMBASE, Health Systems Evidence, CINAHL, SciELO, LILACS, Google Scholar and the CAPES periodicals portal. Data of the included studies was extracted into a pre-formatted sheet and their methodological quality was assessed using AMSTAR 2 tool. Eventually, 15 systematic reviews were included for the narrative synthesis. RESULTS: The interventions were grouped into four categories: (1) strengthening of the triage service; (2) strengthening of the ED’s team; (3) creation of new care zones; (4) change in ED’s work processes. All studies observed positive effect on patient’s length of stay, expect for one, which had positive effect on other indicators. According to AMSTAR 2 criteria, eight revisions were considered of high or moderate methodological quality and seven, low or critically low quality. There was a clear improvement in the quality of the studies, with an improvement in focus and methodology after two decades of systematic studies on the subject. CONCLUSIONS: Despite some limitations, the evidence presented on this overview can be considered the cutting edge of current scientific knowledge on the topic

Efficacy and Safety of Human Retinal Progenitor Cells.

PURPOSE: We assessed the long-term efficacy and safety of human retinal progenitor cells (hRPC) using established rodent models. METHODS: Efficacy of hRPC was tested initially in Royal College of Surgeons (RCS) dystrophic rats immunosuppressed with cyclosporine/dexamethasone. Due to adverse effects of dexamethasone, this drug was omitted from a subsequent dose-ranging study, where different hRPC doses were tested for their ability to preserve visual function (measured by optokinetic head tracking) and retinal structure in RCS rats at 3 to 6 months after grafting. Safety of hRPC was assessed by subretinal transplantation into wild type (WT) rats and NIH-III nude mice, with analysis at 3 to 6 and 9 months after grafting, respectively. RESULTS: The optimal dose of hRPC for preserving visual function/retinal structure in dystrophic rats was 50,000 to 100,000 cells. Human retinal progenitor cells integrated/survived in dystrophic and WT rat retina up to 6 months after grafting and expressed nestin, vimentin, GFAP, and βIII tubulin. Vision and retinal structure remained normal in WT rats injected with hRPC and there was no evidence of tumors. A comparison between dexamethasone-treated and untreated dystrophic rats at 3 months after grafting revealed an unexpected reduction in the baseline visual acuity of dexamethasone-treated animals. CONCLUSIONS: Human retinal progenitor cells appear safe and efficacious in the preclinical models used here. TRANSLATIONAL RELEVANCE: Human retinal progenitor cells could be deployed during early stages of retinal degeneration or in regions of intact retina, without adverse effects on visual function. The ability of dexamethasone to reduce baseline visual acuity in RCS dystrophic rats has important implications for the interpretation of preclinical and clinical cell transplant studies

The impacts of incentive policies on improving private investment for rural electrification in Nigeria – A geospatial study

In Nigeria, 86 million people lack electricity access, the highest number worldwide, predominantly in rural areas. Despite government efforts, constrained budgets necessitate private investors, who, without adequate incentives, are hesitant to commit capital due to perceived high risks. This study identifies three existing incentive policies—concessionary loans, capital subsidy, and financing productive use equipment—aimed at promoting rural electrification in Nigeria. Employing geospatial and regulatory analyses, we evaluate their impact on electrification planning across 22,696 population clusters. While all incentives encourage mini-grids and stand-alone systems, results show varied impacts, predominantly favouring mini-grids. Under the baseline, grid extension is optimal for 66% of clusters, followed by mini-grids (27%) and stand-alone systems (7%). Concessionary loans boost mini-grid and Stand-Alone Systems shares by 10% and 5%, respectively. Capital subsidies increase the mini-grid share to 41%, surpassing concessional loans (37%). Financing productive equipment enhances Stand-Alone Systems and mini-grid shares to 15% and 43%. Incentives impact LCOE, CAPEX, and OPEX, with average LCOE reducing to 0.31 EUR/kWh (concessionary loans), 0.30 EUR/kWh (capital subsidy), and 0.27 EUR/kWh (financing productive use). Financing productive uses proves decisively more effective in lowering costs for mini-grids and stand-alone systems than loans or capital subsidies. The important policy implications of this study reinforce the need for tailored incentives for distinct electrification options

Descarbonizar micro/mini-redes através da complementaridade da produção solar fotovoltaica e eólica

RESUMO: Este trabalho apresenta uma metodologia para determinar a capacidade instalada ótima de fontes de energia renováveis variáveis no tempo, numa mini-rede selecionada, e avaliar o potencial destas tecnologias para satisfazer o consumo de eletricidade, permitindo reduzir a dependência de geradores alimentados por combustíveis fósseis. A capacidade ótima é identificada com base na exploração estratégica da sinergia eólica e solar fotovoltaica (FV) para atender à procura de eletricidade, neste caso, para substituir a produção com geradores a diesel. Para este efeito, neste trabalho, explora-se o uso de diferentes ângulos de azimute e inclinação dos sistemas solares fotovoltaicos fixos (convencionais e bifaciais), bem como sistemas com seguimento para criar um portfólio de geração ideal. Os resultados preliminares obtidos destacam que é necessário diversificar a orientação dos painéis solares e explorar a energia eólica para evitar vários períodos com excesso de produção e, consequentemente, corte de geração. Apesar de ser necessário continuar a desenvolver este trabalho, os resultados mostram que o uso dos geradores a diesel pode ser significativamente reduzido, especialmente durante o período diurno.ABSTRACT: This work presents a methodology to determine the optimal share of variable renewable energy sources (vRES) in a selected mini-grid, and evaluate its ability to satisfy electricity demand, allowing to reduce dependence on generators using fossil fuel. The optimal share is identified based on the strategic exploitation of wind and solar photovoltaic (PV) synergies to meet electricity demand, in this case, to replace the production from diesel generators. To this end, in this work, the use of different azimuth and tilt angles for solar PV systems (conventional and bifacial) as well as tracking systems to create an ideal mix is explored. The preliminary results obtained highlight that it is necessary to diversify the orientation of solar panels and explore wind energy to avoid several periods of generation outages. Although it is necessary to continue developing this work, the results show that the use of diesel generators can be significantly reduced, especially during the day.N/

Incorporating high-resolution demand and techno-economic optimization to evaluate micro-grids into the Open Source Spatial Electrification Tool (OnSSET)

For decades, electrification planning in the developing world has often focused on extending the national grid to increase electricity access. This article draws attention to the potential complementary role of decentralized alternatives – primarily micro-grids – to address universal electricity access targets. To this aim, we propose a methodology consisting of three steps to estimate the LCOE and to size micro-grids for large-scale geo-spatial electrification modelling. In the first step, stochastic load demand profiles are generated for a wide range of settlement archetypes using the open-source RAMP model. In the second step, stochastic optimization is carried by the open-source MicroGridsPy model for combinations of settlement size, load demand profiles and other important techno-economic parameters influencing the LCOE. In the third step, surrogate models are generated to automatically evaluate the LCOE using a multivariate regression of micro-grid optimization results as a function of influencing parameters defining each scenario instance. Our developments coupled to the OnSSET electrification tool reveal an important increase in the cost-competitiveness of micro-grids compared to previous analyses

A renewable energy-centred research agenda for planning and financing Nexus development objectives in rural sub-Saharan Africa

In rural sub-Saharan Africa – the global poverty hotspot – the vast majority of cropland is rainfed only, resulting in reduced and unstable yields. Smallholder farmers account for 80% of agricultural production but they have limited access to relevant services to support both commercial operations and their livelihoods: more than two-thirds of rural dwellers have no access to electricity (crucial for crop irrigation, processing, and storage) and about 40% have no access to clean water. Previous research has analysed integrated technological and resource management approaches to tackle these overlapping development gaps. To finance and implement such transformations in resource-constrained settings, it is now crucial to understand the business and investment implications, also considering the strong regional population growth and the increasing frequency and intensity of climate extremes. Here, we lay out a research agenda that promotes the integration of multi-scale modelling excellence along the climate-water-renewable energy-agriculture-development Nexus and the creation of robust business models for private companies that can sustainably support private smallholder farmers of SSAin their effort to eradicate poverty and inequality. The proposed agenda is a cornerstone of the EC-H2020 project LEAP-RE RE4AFAGRI (“Renewable Energy for African Agriculture: Integrating Modelling Excellence and Robust Business Models”). In proposing the agenda, we highlight the importance of integrating energy access into the Nexus framework from both research and investment perspectives