Showing papers by "University of Córdoba (Spain) published in 2022"

Recent advances in lithium-sulfur batteries using biomass-derived carbons as sulfur host

Abstract: While biomass waste is generated in abundance, these materials and their production processes are generally environmentally friendly, low cost, non-hazardous and easily scalable. These advantages position biomass materials as excellent candidates to solve problems of environmental pollution, primarily by substitution of less sustainable counterparts. This also applies to energy storage systems such as batteries, where several components have large environmental impacts. Lithium–Sulfur batteries have, in this context, been extensively researched to cope with the growing energy needs, and are expected to foresee a growing commercialization. Specifically, advances in the use of renewable cathode materials for Li–S batteries is a field that has been widely addressed in recent years, with carbonaceous materials (C) and/or activated carbons (AC), obtained from biomass, being intensively studied. We here reviewed this field through a classification and discussion of carbonaceous materials from natural waste according to the type of biomass: (1) woody, (2) herbaceous and agricultural, (3) aquatic, (4) animal and human, and (5) contaminated and industrial biomass waste materials. In addition, all porous carbons or activated carbons used as sulfur hosts have been exhaustively evaluated in terms of origin, synthesis parameters, physical properties, and electrochemical performance in Li–S batteries. The purpose is to provide a general description of the progress in the preparation of carbons from biomass resources, examine the textural and electrochemical properties of these materials focusing on the last decade, and also to present an outlook for future research in this developing area.

Visible-LED-light-driven photocatalytic synthesis of N-heterocycles mediated by a polyoxometalate-containing mesoporous zirconium metal-organic framework

Abstract: A mesoporous metal-organic framework with photothermal properties, namely PCN-222, was solvothermally synthesized from meso-tetra(4-carboxyphenyl)porphyrin and zirconium chloride employing both benzoic acid (BA) and trifluoroacetic acid (TFA) as modifiers. The MOF material subsequently served as a porous support for a polyoxometalate (POM), H3PW12O40, via a facile impregnation method which rendered a novel porous POM@PCN-222 composite. The solid was characterized by FT-IR, PXRD, SEM/EDX, TGA/DSC, ICP-OES, UV–Vis DRS, cyclic voltammetry (CV), and BET surface area. The one-pot synthesis of N-heterocycles (pyridine derivatives) was investigated utilizing the hybrid material via one-pot pseudo four-component reaction between aromatic aldehydes, methyl acetoacetate and ammonium acetate promoted under visible LED light irradiation in the presence of molecular oxygen as green oxidant. Products were selectively formed in good yields in the presence of the recyclable heterogeneous solid. Remarkably, POM@PCN-222 showed a superior performance for this procedure as compared to both unfunctionalized MOF and POM. The photosensitizer and photothermal properties of the porphyrin linkers combined with Lewis acidic sites derived from PW12 and Zr6-nodes were responsible for the observed excelling performance. To understand the mechanism, control investigations, electron paramagnetic resonance (EPR) analysis and FT-IR reaction monitoring were performed. The work discloses, for the first time, a simple and environmentally friendly approach for the direct production of pyridines via one-pot thermo-photocatalytic approach using a novel POM-modified MOF in the absence of any chemical additive.

Correlation of banana productivity levels and soil morphological properties using regularized optimal scaling regression

Abstract: Soil morphological properties described in the field, such as texture, consistence or structure, provide a valuable tool for the evaluation of soil productivity potential. In this study, we developed a regression model between the soil morphological variables of banana plantations and a crop Productivity Index (PI) previously developed for the same areas in Venezuela. For this, we implemented categorical regression, an optimal scaling procedure in which the morphological variables are transformed into a numerical scale, and can thus be entered in a multiple regression analysis. The model was developed from data from six plantations growing “Gran Nain” bananas, each with two productivity levels (high and low), in two 4-ha experimental plots, one for each productivity level. Sixty-three A horizons in thirty-six soils were described using 15 field morphological variables on a nominal scale for structure type, texture and hue, and an ordinal scale for the rest (structure grade, structure size, wet and dry consistence, stickiness, plasticity, moist value, chroma, root abundance, root size, biological activity and reaction to HCl). The optimum model selected included biological activity, texture, dry consistence, reaction to HCl and structure type variables. These variables explained the PI with an R2 of 0.599, an expected prediction error (EPE) of 0.645 and a standard error (SE) of 0.135 using bootstrapping, and EPE of 0.662 with a SE of 0.236 using 10-fold cross validation. Our study showed how soil quality is clearly related to productivity on commercial banana plantations, and developed a way to correlate soil quality indicators to yield by using indicators based on easily measured soil morphological parameters. The methodology used in this study might be further expanded to other banana-producing areas to help identify the soils most suitable for its cultivation, thereby enhancing its environmental sustainability and profitability.

Biodiesel Is Dead: Long Life to Advanced Biofuels—A Comprehensive Critical Review

Abstract: Many countries are immersed in several strategies to reduce the carbon dioxide (CO2) emissions of internal combustion engines. One option is the substitution of these engines by electric and/or hydrogen engines. However, apart from the strategic and logistical difficulties associated with this change, the application of electric or hydrogen engines in heavy transport, e.g., trucks, shipping, and aircrafts, also presents technological difficulties in the short-medium term. In addition, the replacement of the current car fleet will take decades. This is why the use of biofuels is presented as the only viable alternative to diminishing CO2 emissions in the very near future. Nowadays, it is assumed that vegetable oils will be the main raw material for replacing fossil fuels in diesel engines. In this context, it has also been assumed that the reduction in the viscosity of straight vegetable oils (SVO) must be performed through a transesterification reaction with methanol in order to obtain the mixture of fatty acid methyl esters (FAMEs) that constitute biodiesel. Nevertheless, the complexity in the industrial production of this biofuel, mainly due to the costs of eliminating the glycerol produced, has caused a significant delay in the energy transition. For this reason, several advanced biofuels that avoid the glycerol production and exhibit similar properties to fossil diesel have been developed. In this way, “green diesels” have emerged as products of different processes, such as the cracking or pyrolysis of vegetable oil, as well as catalytic (hydro)cracking. In addition, some biodiesel-like biofuels, such as Gliperol (DMC-Biod) or Ecodiesel, as well as straight vegetable oils, in blends with plant-based sources with low viscosity have been described as renewable biofuels capable of performing in combustion ignition engines. After evaluating the research carried out in the last decades, it can be concluded that green diesel and biodiesel-like biofuels could constitute the main alternative to addressing the energy transition, although green diesel will be the principal option in aviation fuel.

Consensus Statement on Hemostatic Management, Anticoagulation, and Antiplatelet Therapy in Liver Transplantation

Abstract: Anticoagulation and antiplatelet therapies are increasingly used in liver transplant (LT) candidates and recipients due to cardiovascular comorbidities, portal vein thrombosis, or to manage posttransplant complications. The implementation of the new direct-acting oral anticoagulants and the recently developed antiplatelet drugs is a great challenge for transplant teams worldwide, as their activity must be monitored and their complications managed, in the absence of robust scientific evidence. In this changing and clinically heterogeneous scenario, the Spanish Society of Liver Transplantation and the Spanish Society of Thrombosis and Haemostasis aimed to achieve consensus regarding the indications, drugs, dosing, and timing of anticoagulation and antiplatelet therapies initiated from the inclusion of the patient on the waiting list to post-LT surveillance. A multidisciplinary group of experts composed by transplant hepatologists, surgeons, hematologists, transplant-specialized anesthesiologists, and intensivists performed a comprehensive review of the literature and identified 21 clinically relevant questions using the patient-intervention-comparison-outcome format. A preliminary list of recommendations was drafted and further validated using a modified Delphi approach by a panel of 24 transplant delegates, each representing a LT institution in Spain. The present consensus statement contains the key recommendations together with the core supporting scientific evidence, which will provide guidance for improved and more homogeneous clinical decision making.

Transcriptional regulation of photoprotection in dark-to-light transition—More than just a matter of excess light energy

Abstract: In nature, photosynthetic organisms are exposed to different light spectra and intensities depending on the time of day and atmospheric and environmental conditions. When photosynthetic cells absorb excess light, they induce nonphotochemical quenching to avoid photodamage and trigger expression of "photoprotective" genes. In this work, we used the green alga Chlamydomonas reinhardtii to assess the impact of light intensity, light quality, photosynthetic electron transport, and carbon dioxide on induction of the photoprotective genes (LHCSR1, LHCSR3, and PSBS) during dark-to-light transitions. Induction (mRNA accumulation) occurred at very low light intensity and was independently modulated by blue and ultraviolet B radiation through specific photoreceptors; only LHCSR3 was strongly controlled by carbon dioxide levels through a putative enhancer function of CIA5, a transcription factor that controls genes of the carbon concentrating mechanism. We propose a model that integrates inputs of independent signaling pathways and how they may help the cells anticipate diel conditions and survive in a dynamic light environment.

Graphic representation of the degree of historical-archaeological evidence: the 3D reconstruction of the “Baker’s House”

Abstract: Abstract Over the years, the methodologies used for graphic representation in archaeology have evolved. The substantial change in representation was achieved with the use of computer software. Currently, 3D sketch scanning and photogrammetry are predominating tools used in this field. A new methodology, i.e., the use of the historical-archaeological evidence level scale, has entered this discipline to show the veracity of archaeological studies, as well as that of the vestiges found. The present study is focused on the virtual reconstruction of the ‘Baker’s House’ in the archaeological site of Torreparedones (Córdoba, Spain). The main aim of this study was to show and identify the veracity of the obtained reconstruction, through the use of the historical-archaeological evidence scale and the elaboration of a typological rank. The methodology used shows the evidence level employed by experts in the creation of virtual representations. The dissemination of the proposed historical-archaeological evidence scale entails the graphical identification of the veracity of reconstructions in this type of representations, always complying with the scientific quality criteria established by the Seville Letter.

Adolescent Involvement in Cybergossip: Influence on Social Adjustment, Bullying and Cyberbullying

Abstract: Gossip is a type of social behavior present in all types of social networks, and cybergossip is an emerging kind of online social behavior which can both promote and hinder relationships between peers. The aim of this study was to explore the relation between involvement in cybergossip and the development of behavior of social adjustment, bullying and cyberbullying (aggression and victimization), based on gender and age. A total of 510 secondary school students (49.4% girls) aged 12 to 17 years old (M = 14.01; SD = 1.38) were surveyed by self-report. Questionnaires validated with adolescents were used to measure bullying, social adjustment and cyberbullying. The results showed that a high prevalence of involvement in cybergossip was associated with bullying and cyberbullying behavior (aggression and victimization), with girls showing the greatest involvement in cybergossip. The discussion of the results focuses on the gender difference, as well as the importance of the need for training in the proper use of digital devices for social education and socialization.

Carbon Sequestration in Carob (Ceratonia siliqua L.) Plantations under the EU Afforestation Program in Southern Spain Using Low-Density Aerial Laser Scanning (ALS) Data

Abstract: Climate change is one of the environmental issues of global dominance and public opinion, becoming the greatest environmental challenge and of interest to researchers. In this context, planting trees on marginal agricultural land is considered a favourable measure to alleviate climate change, as they act as carbon sinks. Aerial laser scanning (ALS) data is an emerging technology for quantitative measures of C stocks. In this study, an estimation was made of the gains of C in biomass and soil in carob (Ceratonia siliqua L.) plantations established on agricultural land in southern Spain. The average above-ground biomass (AGB) corresponded to 85.5% of the total biomass (average 34.01 kg tree−1), and the root biomass (BGB) was 14.5% (6.96 kg tree−1), with a BGB/AGB ratio of 0.20. The total SOC stock in the top 20 cm of the soil (SOC-S20) was 60.70 Mg C ha−1 underneath the tree crown and 43.63 Mg C ha−1 on the non-cover (implantation) area for the C. siliqua plantations. The allometric equations correlating the biomass fractions with the dbh and Ht as independent variables showed an adequate fit for the foliage (Wf, R2adj = 0.70), whereas the fits were weaker for the rest of the fractions (R2adj < 0.60). The individual trees were detected using colour orthophotography and the tree height was estimated from 140 crowns previously delineated using the 95th percentile ALS-metric. The precision of the adjusted models was verified by plotting the correlation between the LiDAR-predicted height (HL) and the field data (R2adj = 0.80; RMSE = 0.53 m). Following the selection of the independent variable data, a linear regression model was selected for dbh estimation (R2adj = 0.64), and a potential regression model was selected for the SOC (R2adj = 0.81). Using the segmentation process, a total of 8324 trees were outlined in the study area, with an average height of 3.81 m. The biomass C stock, comprising both above- and below-ground biomass, was 4.30 Mg C ha−1 (50.67 kg tree−1), and the SOC20-S was 37.45 Mg C ha−1. The carbon accumulation rate in the biomass was 1.94 kg C tree−1 yr−1 for the plantation period. The total C stock (W-S and SOC20-S) reached 41.75 Mg ha−1 and a total of 4091.5 Mg C for the whole plantation. Gleaned from the synergy of tree cartography and these models, the distribution maps with foreseen values of average C stocks in the planted area illustrate a mosaic of C stock patterns in the carob tree plantation.