Universidad Central "Marta Abreu" de las Villas
Recent publications
Despite the great electrification that vehicle fleet is expecting in the coming years, internal combustion engines still play an important role in the transport sector. New regulations for polluting emission reduction and economy decarbonization, together with lower availability of fuels from non-renewable sources, have led to the search of renewable non-polluting fuels. This is a fundamental research sector in the next decades. Biodiesel, with a long history, has proven to be a good candidate. However, diversification will be the key to success in terms of sustainable mobility, avoiding negative dependency in the future. In this context, discarded oil is key to both produce an economically affordable biodiesel and to valorize this residue. This research studies the possibility of using a binary mix of fuels, including primary alcohols (propanol and pentanol), at 10 and 20% v/v, with highly-oxidized dumped oil biodiesel. These mixtures have been tested in a diesel engine running at 1300, 1700 and 2400 rpm, under 25% and 46% engine load for each rotational speed. To check the significance and reproducibility of obtained data, polluting emissions and engine input parameters have been evaluated through descriptive and inferential statistics. Results indicate that 20% 1-propanol/biodiesel blend allows mitigating the increase in fuel consumption of biodiesel compared to fossil diesel fuel. Moreover, overall soluble organic fraction (SOF) and unburned hydrocarbon emissions are lower for biodiesel and its blends than for diesel fuel. Furthermore, the combination of the use of 10% propanol and maximum EGR valve opening can achieve a significant reduction of NOx emissions. As a final conclusion, the proposed statistical study has shown to be a reliable tool to compare emissions and input parameters from different tests, especially under intra-urban conditions. This overcomes the large data variability from emission tests.
Purpose This study aims to assess environmentally three different alternatives related to the valorization of Dichrostachys cinerea tree (an invasive plant) as a feedstock for cogeneration facilities installed in the sugarcane industry in Cuba. Methods The Life Cycle Assessment (LCA) methodology was applied to three cogeneration alternatives: (A-1) Electric- ity generation using raw Dichrostachys cinerea (marabou) as fuel in a back-pressure steam turbine cycle, (A-2) Electricity generation using torrefied marabou as fuel in a back-pressure steam turbine cycle, and (A-3) Electricity generation using torrefied marabou as fuel in an extraction-condensing turbines cycle. The SimaPro software was used for the inventory modeling and the ReCiPe method (midpoint and endpoint approach) was applied to estimate the environmental impacts associated with each case. Results and Discussion The LCA results showed that the electricity generation from torrefied marabou using extraction- condensing turbines (A-3) reduces the environmental impacts as compared with A-1 and A-2. This performance is explained by a lower marabou relative consumption (1.85 kg marabou/kWh generated), which leads to lower emissions associated with harvesting, transportation, and pre-processing stages. Fine Particulate Matter Formation, Terrestrial Acidification, and Water Consumption accounted the worst performance for all the scenarios. Marine Ecotoxicity was the impact category with better environmental performance due to the substitution of synthetic mineral fertilizers by the ashes produced during com- bustion. The Human health damage category reached the higher impacts on the torrefaction subsystem in the A-3 scenario, representing over 94% of the total environmental burden of the process, causing injuries in respiratory systems. The highest beneficial impact of the cogeneration stage was associated with the consideration of residual steam as an avoided product. Conclusions The use of torrefied marabou in extraction-condensing steam turbines can be considered as an environmental- friendly technology in the Cuban context.
Las desigualdades ideológicamente fundadas sobre el concepto biológico de género, determinadas por la herencia sociopatriarcal, han regido históricamente el pensamiento humano. Cuba no escapa de esta realidad y continúa reproduciendo estereotipos sexistas en la construcción de género en sus medios de comunicación. La presente investigación analiza desde una perspectiva cualitativa las asignaciones de género establecidas en el discurso publicitario comercial del canal Cubavisión Internacional (CVI) durante el año 2019, único medio audiovisual institucional en Cuba concebido para público internacional. Se emplea como método el análisis del discurso multimodal y como técnica la entrevista a emisores del canal y a expertos en género y publicidad televisiva. El análisis demuestra que, en el discurso publicitario de CVI, los estereotipos son la base para construir el género; por ello, se explicita la diferencia marcada de paradigmas femeninos y masculinos y la omisión de otros genéricos con preceptos tradicionales. Estos presupuestos inciden en la configuración de una identidad folclorista que asocia Cuba y sus habitantes con un destino turístico heteronormativo, lo que demuestra la permanencia de un discurso publicitario conservador.
Hyperhydricity can affect the development of plant morphology. A better understanding of the anatomical and physiological changes of hyperhydric plants is needed to predict and control the occurrence of hyperhydryc conditions. The aim of this study is to demonstrate the role of oxidative stress in hyperhydricity. To this end, the anatomical, physiological and biochemical responses to oxidative stress in shoots of Bambusa vulgaris Schrad. ex Wendl were compared during the in vitro-ex vitro transition. For this propose, we used shoots grown in two different culture systems: liquid static culture medium and temporary immersion system. Our results showed that hyperhydricity was associated with oxidative stress in the shoots. In hyperhydric shoots chlorophyll content decreased when cultured in liquid static culture medium. Moreover, hydrogen peroxide content and malondialdehyde, as well as the activities of catalase and enzymes of ascorbate-glutathione cycle (ascorbate peroxidase, monodehydroascorbate reductase and dehydroascorbate reductase) were increased in these shoots. On the other hand, scanning electron microscopy showed that the leaves of hyperhydric shoots exhibited anatomical changes in the stomata of the plants, whereas the leaves of normal shoots showed normal structural development. Finally, normal shoots showed high survival rate and allowed better adaptation of the plantlets in the greenhouse.
El Comportamiento Informacional Web y la Experiencia de Usuario son disciplinas científicas que comparten aspectos comunes. No se evidencian estudios precedentes que delimiten las relaciones entre las disciplinas Comportamiento Informacional Web y Experiencia de Usuario desde la perspectiva métrica. Se planteó como objetivo del estudio: caracterizar las relaciones entre las disciplinas Comportamiento Informacional Web y Experiencia de Usuario desde el análisis de la producción científica de las disciplinas del conocimiento. Para la obtención de resultados se emplearon métodos en los niveles teórico y empírico, fundamentalmente el bibliométrico. Se concluye que los estudios de comportamiento informacional de usuarios a nivel internacional contemplan el espacio Web para determinar cómo es la interacción. El análisis de las disciplinas científicas a partir de su producción permitió la identificación de las relaciones en temáticas, instituciones, países, idiomas, entre otras. La relación disciplinar entre relación disciplinar del Comportamiento Informacional Web y la Experiencia de Usuario es incipiente. Existen puntos en común sobre todo en el empleo de técnicas para el estudio de usuario, pero no se concibe explícitamente la relación entre ambas disciplinas.
In the last two decades many reports have addressed the application of artificial intelligence (AI) in the search and design of antimicrobial peptides (AMPs). AI has been represented by machine learning (ML) algorithms that use sequence-based features for the discovery of new peptidic scaffolds with promising biological activity. From AI perspective, evolutionary algorithms have been also applied to the rational generation of peptide libraries aimed at the optimization/design of AMPs. However, the literature has scarcely dedicated to other emerging non-conventional in silico approaches for the search/design of such bioactive peptides. Thus, the first motivation here is to bring up some non-standard peptide features that have been used to build classical ML predictive models. Secondly, it is valuable to highlight emerging ML algorithms and alternative computational tools to predict/design AMPs as well as to explore their chemical space. Another point worthy of mention is the recent application of evolutionary algorithms that actually simulate sequence evolution to both the generation of diversity-oriented peptide libraries and the optimization of hit peptides. Last but not least, included here some new considerations in proteogenomic analyses currently incorporated into the computational workflow for unravelling AMPs in natural sources.
Imbalanced data are popular in the machine learning community due to their likelihood of appearing in real-world application areas and the problems they present for classical classifiers. The goal of this work is to extend the capabilities of prototype-based classifiers using fuzzy similarity relations and to make them sensitive to class-imbalanced data classification. This paper proposes two new fuzzy logic-based prototype selection classifiers for imbalanced datasets, Imb-SPBASIR-Fuzzy_V1 (FPS-v1) and Imb-SPBASIR-Fuzzy_V2 (FPS-v1), and shows a comparative study of them with state-of-the-art methods on public datasets from the UCI machine learning repository. The results on the selected datasets suggest that fuzzy logic-based prototype selection classifiers perform well and efficiently, indicating that it is a viable alternative. The fuzzy relationships provided by this approach allow better results than the state-of-the-art models. Further analysis showed that the proposed fuzzy-based prototypes methods permit obtaining more accurate to deal with the correct prophylaxis, timely diagnosis and treatment of postoperative mediastinitis.
The strength of the pipe region opposite to the weld in a high wall thickness sour service pipeline steel API 5L X65, manufactured by the SAW UOE process, has been studied in detail. The fundamental hardening mechanisms that contribute to the yield strength of this pipe portion were determined according to its microstructural features before and after post-weld stress relieving heat treatment. The root mean square summation of the different strengthening mechanisms resulted in a reasonable estimate of the yield strength of this pipe portion before the heat treatment. The contributions of the different strengthening mechanisms proceeded at different length scales in this pipe portion before and after the heat treatment. The heat treatment at 650 ºC (1.5 h) reduced the contributions of the strengthening mechanisms to the steel yield strength corresponding to this pipe portion. The dislocation strengthening contribution decreased by approximately 50%. The precipitation hardening and the solid solution and grain size strengthening reduced their contributions by approximately 14% and 3% respectively.
Introduction Relapse are a hallmark of multiple sclerosis, being a characteristic feature of relapsing-remitting multiple sclerosis (RRMS). The occurrence of a relapse constitutes a source of significant discomfort that impacts all domains of daily life of patients with multiple sclerosis (PwMS). In this study we first explored the psychometric properties of the Spanish version of the Fear of Relapse Scale (FoR) in a sample of patients with RRMS. Besides, we explored the relationship between the Fear of Relapse Scale with fatigue and cognitive perceived deficits in our PwMS sample. Methods An online cross-sectional survey was conducted on 173 MS patients from 12 Spanish-speaking countries (Argentina, Mexico, Uruguay, Dominican Republic, Spain, Cuba, Colombia, Guatemala, Chile, Paraguay, Peru, and El Salvador). Confirmatory factor analysis (CFA) was performed to assess the factor structure of the scale. Multiple linear regression was used to evaluate the effects of health self-perception, fatigue and cognitive perceived deficits over fear of relapse. Results The three-factor model in the CFA yielded a good model fit (χ²/df = 2.25, p < .001, RMSEA = .078, CFI = .91). McDonalds' Omega of the FoR (Spanish version) was .91. There was a statistically significant and inverse correlation between FoR and health self-perception, and a positive correlation between FoR, fatigue and cognitive perceived deficits. Finally, level of fatigue was a predictors of fear of relapse. Conclusions The Spanish version of the Fear of Relapse Scale is a valid and reliable instrument to explore the experience of fear of relapse in patients with RRMS.
The wastewater generated in the dairy industry contains amounts of contaminants such as hormones and dyes, which are harmful to public health. That is why this wastewater, before being dumped into water bodies, must have an effective treatment that guarantees the degradation of these pollutants. The aim of the present research work is to evaluate the advanced oxidation processes (AOPs), in treatment by the photo-Fenton system, for binary solution Blue 1 (B1)-Estradiol (E1); through the comparison of the radiation in Sunlight and UV-C photo reactors. The influence of the doses of [Fe], [H2O2], and pH in the photo-Fenton reaction was evaluated, preparing samples of 50 mL of these parameters, through a factorial design. The kinetic study was carried out considering the initial conditions of [Fe] 3 mg L-1 , [H2O2] 180 mg L-1, and pH 3, determining the degradation percentage at 15, 30, 45, 60, 90, 120, 180 minutes of radiation exposure. The photo-Fenton/Sunlight system showed for both substances a rapid degradation, reaching 100% of degradation after 180 min of operation; however, for the photo-Fenton/UV-C system, the same percentage of degradation was evidenced for B1 (100%), and a decrease in the percentage of degradation for E1 (89.48%).
It is investigated the potential short-term influence of a solar storm on micro-algal photosynthesis. From the secondary cosmic rays at sea level we focus on muons, given their high penetrating power, and it is considered that a ‘’generic’’ solar storm would imply an increase of 10% in both muon fluxes and their average energy. It is then assumed an exponential decay of muon fluxes down the water column and a direct proportionality between their penetrating power and energy. This allows obtaining a function of ionizing radiation to be embedded in a physical-mathematical model for photosynthesis previously modified by some of us to include particulate ionizing radiation. It is finally shown that solar storms can cause a significant short-term depletion of photosynthesis in both ocean and coastal waters.
Sugarcane bagasse (SCB) was pretreated with 1-butyl-3-methylimidazolium chloride (BmimCl) at different conditions of temperature (80 °C to 150 °C) and solid loading (4 to 10%) at two times (20 and 60 min). The pretreatment conditions were optimized using a central composite rotatable design (CCRD) and desirability function having in mind the principles of green engineering. The pretreatments resulted in modifications of morphological and structural characteristics of biomass, also resulting in partial hemicellulose reduction. The founded optimal condition of pretreatment under the criterion of maximized sugar yield after enzymatic hydrolysis and minimized total sugar loss in pretreatment was 140 °C and 6% w/w of solid loading with 20 min of process. Also, a kinetic model was obtained verifying its validity with experimental values. It showed a lower activation energy of cellulose modification and hemicellulose conversion in comparison with the literature. One of the major findings was the strong correlation between glucose conversion and the degree of polymerization.
With the advancement of combinatorial chemistry and big data, drug repositioning has boomed. In this sense, machine learning and artificial intelligence techniques offer a priori information to identify the most promising candidates. In this study, we combine QSAR and docking methodologies to identify compounds with potential inhibitory activity of vasoactive metalloproteases for the treatment of cardiovascular diseases. To develop this study, we used a database of 191 thermolysin inhibitor compounds, which is the largest as far as we know. First, we use Dragon's molecular descriptors (0-3D) to develop classification models using Bayesian networks (Naive Bayes) and artificial neural networks (Multilayer Perceptron). The obtained models are used for virtual screening of small molecules in the international DrugBank database. Second, docking experiments are carried out for all three enzymes using the Autodock Vina program, to identify possible interactions with the active site of human metalloproteases. As a result, high-performance artificial intelligence QSAR models are obtained for training and prediction sets. These allowed the identification of 18 compounds with potential inhibitory activity and an adequate oral bioavailability profile, which were evaluated using docking. Four of them showed high binding energies for the three enzymes, and we propose them as potential dual ACE/NEP inhibitors for the control of blood pressure. In summary, the in silico strategies used here constitute an important tool for the early identification of new antihypertensive drug candidates, with substantial savings in time and money. Graphic abstract
The objective of this study was to explore the relationship between sociodemographic factors and fear of COVID-19 in a Cuban population. A web-based study with a cross-sectional design was conducted. The sample comprised 1,145 participants. To explore fear, the Fear of COVID-19 Scale was used. Our results suggest that women were more likely to experience medium to high levels fear compared to men. Additionally, knowing a person positive for COVID-19 significantly increases fear levels in Cuban participants.
Biomass combustion for electric energy production is associated with corrosion. The formation of unwanted deposits on heat-exchanger surfaces with significant concentrations of alkaline species of K and Na, as well as S and Cl, are the cause. Modern biomass power plants operate at temperatures that exceed those where corrosion is not so severe. At high temperatures, molten salts deposits increase the corrosion rate. Molten sulfates are the most common cause of molten-salt corrosion, as they can dissolve the protective oxide layer, even on stainless steels alloys. Active oxidation occurs in an oxidizing environment in the presence of chlorine (KCl or NaCl) at high temperatures. Molten chlorinated compounds have great influence despite the fact that the melting temperature of KCl (s) is 774 °C, since this compound together with other substances forms eutectics at much lower temperatures that increase the corrosion rate. The high corrosiveness of biomass requires the use of more resistant steels and proposals are made for the most effective alloys. Aditionally, to reduce the effect of alkalis and chlorides, variants are analysed as co-combustion with biomass less loaded in alkalis and chlorides, the addition of sulphur compounds to convert the chlorides of low melting point into sulfates of higher melting point; the pretreatment by leaching of the biomass to reduce compounds that compromise its use or to include solutions in the design of the plants that prevent the arrival of corrosive compounds to the superheater.
To respond to the rapid introduction and development of calcined clays as supplementary cementitious material (SCM), the toolbox of characterization methods for cementitious materials requires extension to raw clay characterization. Borrowing concepts and methods developed in the field of clay mineralogy, this paper outlines the merits and limits of widely accessible characterization techniques for raw clays intended for use as SCM, when calcined. The paper focuses mainly on the identification and quantification of the raw clay mineral components, as these characteristics have important implications for further material processing and performance. General notes are provided on clay sampling and pre-treatment as well as bulk chemical analysis. The main techniques considered are X-ray diffraction, thermal analysis and infrared spectroscopy. Their application on raw clays is introduced, highlighting clay-specific aspects of sample preparation, data acquisition, and processing. Guidelines and interpretation tables are provided to aid in the analysis of the acquired data, while limitations and potential interferences are identified. Options for remote prospection by infrared spectroscopy are included as well. To illustrate the type of information to be gained and the complementarity of the techniques, two representative raw clays are fully characterised. This paper aims to highlight that mineralogical characterization is a feasible and often necessary step in the study and assessment of raw clays that can deliver a wealth of informative data if carried out appropriately.
Environmental pollution as the result effluents discharged by industry is increasing, principally owing to mixtures of pollutants, including dyes. The objective of the present study was to evaluate the adsorption process of the bicomponent mixture of Tartrazine (Y5) and Brilliant Blue FCF (B1) dyes in a dynamic regime (fixed-bed column), using rice husks (RH) as adsorbent material. A 3-level response surface design of experiments was employed to evaluate the adsorption process of the dyes in the mixture at the following initial concentrations: 0.0216, 0.0739, 0.1261, 0.1477 (mmol L-1). The response surface analysis of the experimental design made it possible to identify a competitive adsorption of both dyes. RH had higher affinity for B1, although the adsorption capacity changed depending on the concentration of each dye in the mixture. The highest RH adsorption capacity was 3.4 mg g-1 for B1 and 1.45 mg g-1 for Y5, respectively, under a monocomponent condition. It was considered that the interactions in the mechanism proposed for the adsorption process occurred because of the formation of hydrogen bonds between the sulfonate groups of the dyes and the-OH groups present on the surface of the adsorbent. B1 had a higher affinity towards RH because it had one more sulfonate group than Y5. The multiple-response optimization results make it possible to recommend the use of RH beds with low concentrations of B1 and Y5 in the same feed.
(1) Background: A proposal for the automatic control of sugar cane honey factories based on simulation with real data is presented. (2) Methods: The P&ID diagram of the artisanal process is designed, as well as the measurement and control systems of the different process variables. A data acquisition and monitoring system is proposed with all the required equipment. Using GNU Octave software, the process was simulated, where the transfer functions and parameters of the different stages were determined. The transient responses of these systems are determined before step-jump type disturbances, as well as that of the controllers. (3) Results: A correct adjustment of the controllers is obtained, indicating those that work in a stable way before disturbance variations in the real ranges of plant work. (4) Conclusions: Simulation of controllers before different forcing functions in the ranges of the operating parameters allowed for establishing dynamic responses of each one, demonstrating that they are capable of adjusting the value of the variable of interest or the control, and determining control of the main operating variables.
Despite specific historical, geographical, sociodemographic, and infrastructural conditions that in combination could produce very high levels of energy vulnerability, there are significant and enduring knowledge gaps concerning energy poverty in Latin America and the Caribbean. Bringing together a multi-disciplinary and multi-national team, we focus on establishing the state-of-the-art in knowledge and policy for 5 diverse case studies - Argentina, Brazil, Colombia, Cuba, and Mexico - as well as for the wider region. Our article has three specific aims: to establish the range of approaches used to research energy poverty across the region; to examine national and supranational policy obligations; and to lay the framework for new research and policy agendas. In combination, our extensive academic and grey literature reviews, and accompanying scientometric, legal and statistical analyses, confirm that energy poverty is a relatively nascent topic, with only 62 scientific articles on the region published since 1991. From this body of knowledge, we identify key differences in the geographies of energy poverty identified by different metrics, with energy services-based approaches generally indicating higher vulnerability within rural areas, while energy expenditure metrics point towards higher risk in urban areas. We also find a dominance of quantitative approaches that tend to use existing (and often limited) forms of survey data, and a relative absence of detailed qualitative research. As such, we argue there is an urgent need for transformative research and policy activities within Latin America and the Caribbean, in order to support access to clean, reliable, and affordable energy services for all.
The sustainable development of society and the pressure over the use of cleaner technologies have become essential for mankind to avoid climate change. Dichrostachys cinerea (marabou) is a widely grown invasive tree species across the forest in Cuba, considered as an unsolved problem with high potential to be used as a biofuel. This study aims to perform a critical review on the maturity status of thermochemical conversion processes (torrefaction, pyrolysis, gasification, and combustion) using marabou as high-quality biomass to produce a sustainable biofuel. According to the thermochemical properties of marabou, it could be considered as a promising novel feedstock to produce a high-quality biofuel. The current development of thermochemical conversion technologies with the main operating parameters is studied. Combustion is becoming the widespread technology at medium/large scale; however, biomass gasification is the most promising technology at small scale, mainly in off-grid rural communities. Despite torrefaction being in their early stage of research, preliminary studies suggest that is the most economically feasible alternative. To accelerate the commercialization, reduction of pollutant emissions, application of catalyst-based mechanisms and optimization in supply areas are hotspots. The emphasis of this review is to promote the sustainable use of an invasive tree in a developing country as a case study, which can be exploited as an energy resource, providing local and regional incomes, and new investment opportunities not only in small countries but also in isolated areas from large countries.
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1,852 members
Lizet Rodríguez-Machín
  • Centre for Energy Studies and Environmental Technologies (CEETA)
Miguel Angel Cabrera
  • Unit of Modeling and Experimental Biopharmaceutics
Alberto Taboada-Crispi
  • Informatics Research Center
Ernesto Villar Cociña
  • Faculty of Mathematics, Physics and Computing
Carretera a Camajuaní km 5 1/2, 54830, Santa Clara, Villa Clara, Cuba
Head of institution
Dra. Osana Molerio Pérez