University of the Andes

CO2 emissions have raised alerts worldwide due to their contribution to global warming. Thus, many efforts have been made to develop technologies to capture CO2 from the atmosphere and interest in utilizing adsorbents originating from natural raw sources increasing sustainability. In this work, Zeolite-A was synthesized from Kaolin material. Kaolin was previously calcined at 650 °C to form the Metakaolin. The obtained Metakaolin was submitted to hydrothermal treatment in an aqueous solution of sodium hydroxide and treated at 60 °C for 24 h without using other sources of silica and alumina species. The materials were characterized by X-ray diffraction (XRD), ²⁷Al NMR, infrared spectroscopy (FTIR), N2-physisorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The synthesized Zeolite-A material was evaluated in the CO2 adsorption on a fixed bed reactor using a continuous flow system. The Yoon–Nelson model was used to predict the breakthrough behavior of CO2 adsorption in a fixed bed reactor using Zeolite-A material as an adsorbent. The role of pretreatment temperature of Zeolite-A prior to the CO2 adsorption capacity was accessed. Three different pre-treatment temperatures were used: 100 °C, 300 °C, and 400 °C. The Zeolite-A pretreated at 400 °C (Zeolite-A-400) exhibited the highest surface area. The CO2 adsorption kinetics of the Zeolite-A materials indicated a pseudo-first-order (PFO) kinetics suggesting physical adsorption of CO2 species on the Zeolite materials along with an intraparticle diffusion as the rate-controlling step of the whole adsorption process. The Yoon–Nelson rate constant (kYN) values and the time (τ) required for 50% adsorbate breakthrough offered pieces of evidence for the rationalization of the superior adsorption capacity noticed for the Zeolite-A-400 sample. Graphical Abstract

This article discloses the synthesis of four new positional isomeric zwitterionic ligands exhibiting semi-flexible and flexible characteristics—n-pyridinium-1,2,3-triazole-4-carboxy-5-Acetate (n-PTCA), and n-methylpyridinium-1,2,3-triazole-4-carboxy-5-Acetate (n-MPTCA; where n = 3, 4)—which were derived from an aqueous solution of the corresponding sodium salts in an acidic medium (HCl). These compounds are successfully synthesized and characterized with FT-IR and multinuclear NMR spectroscopy; likewise, proper single crystals are obtained for each compound. All compounds adopt zwitterionic forms in the solid state, which are stabilized via intermolecular proton transfer processes involving HCl and solvent molecules. A single-crystal X-ray analysis revealed how positional isomerism and molecular flexibility influence the supramolecular topology. Specifically, 3-PTCA and 4-PTCA exhibit isomorphic hydrogen bond networks, while 3-MPTCA and 4-MPTCA display distinct packing motifs, attributed to the presence of a methylene spacer between the pyridinium and triazole rings. The Hirshfeld surface analysis quantitatively confirmed the dominance of O···H/H···O and N···H/H···N interactions in the solid-state architecture. These strong hydrogen-bonding networks are indicative of the potential proton-conductive behavior in the crystalline state, positioning these compounds as promising candidates for applications in proton-conducting materials. The structural insights gained underscore the pivotal role of molecular topology in tailoring crystal packing, with implications for the rational design of zwitterionic ligands in functional materials, including MOFs and coordination polymers. The calculated HOMO-LUMO energy gaps reveal a significant electronic variability among the ligands, influenced primarily by the positional isomerism and structural flexibility introduced by the methylene spacer.

This work presents a novel methodology for deriving stationary and axially symmetric solutions to Einstein’s field equations using the 1+3 1 + 3 tetrad formalism. This approach reformulates the Einstein equations into first-order scalar equations, enabling systematic resolution in vacuum scenarios. We derive two distinct solutions in polar and hyperbolic geometries by assuming the separability of a key metric function. Our method reproduces well-known solutions such as Schwarzschild and Kerr metrics and extends the case of rotating spacetimes to hyperbolic configurations. Additionally, we explore the role of Killing tensors in enabling separable metric components, simplifying analyses of geodesic motion and physical phenomena. This framework demonstrates robustness and adaptability for addressing the complexities of axially symmetric spacetimes, paving the way for further applications to Kerr-like solutions in General Relativity.

High-risk industries like mining must address occupational safety to reduce accidents and fatalities. Training through role-playing, simulations, and Serious Games (SGs) can reduce occupational risks. This study aims to conduct a systematic literature review (SLR) on SG methodologies for the mining sector. This review was based on a methodology inspired by the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Three research questions were formulated to explore how SGs contribute to immediate feedback, brain stimulation, and training for high-risk scenarios. The review initially identified 1987 studies, which were reduced to 30 relevant publications following a three-phase process: (1) A search string based on three research questions was defined and applied to databases. (2) Publications were filtered by title and abstract. (3) A full-text reading was conducted to select relevant publications. The SLR showed SG development methodologies with structured processes that are adaptable to any case study. Additionally, it was found that Virtual Reality, despite its implementation costs, is the most used technology for safety training, inspection, and operation of heavy machinery. The first conclusion of this SLR indicates the lack of methodologies for the development of SG for training in the mining field, and the relevance of carrying out specific methodological studies in this field. Additionally, the main findings obtained from this SLR are the following: (1) Modeling languages (e.g., GML and UML) and metamodeling are important in SG development. (2) SG is a significant mechanism for cooperative and participative learning strategies. (3) Virtual Reality technology is widely used in safe virtual environments for mining training. (4) There is a need for methodologies that integrate the specification of cognitive functions with the affective part of the users for SGs suitable for learning environments. Finally, this review highlights critical gaps in current research and underscores the need for more integrative approaches to SG development.

La historia del hombre ha sido construida con dolor, sin embargo, cada dolor genera una esperanza, cada esperanza procura encontrar un camino hacia la libertad, pero a cada paso el camino se cierra haciendo nacer nuevas necesidades de esa libertad siempre buscada.

El presente artículo discute algunos resultados de una investigación exploratoria realizada en Mérida (Venezuela) sobre la percepción de la gravedad del delito por parte de un sector de la población urbana, y que se inserta dentro de una línea de investigación sobre actitudes hacia el ordenamiento jurídico penal.

La lectura crítica como proceso al servicio del aprendizaje significativo en la universidad, constituye un modo de profundizar en el conocimiento científico que producen las comunidades académicas. Esta investigación como resultado de una revisión documental procura integrar las voces de varios autores, asumidos referentes para la construcción de un acercamiento conceptual y operativo a la lectura crítica, a la que se entiende como un modo de desarrollar el pensamiento para zambullirse con profundidad en el saber, en la búsqueda de razonamientos sólidos, planteamientos fundados en datos confiables y fidedignos, así como posiciones falaces que en sus contenidos intentan la reproducción de interpretaciones erradas. Como resultado de colocar en relación los referentes teóricos sobre la lectura crítica, se proponen una serie de interrogantes que el docente en su praxis pedagógica cotidiana puede involucrar, con la finalidad de formar lectores autónomos, competentes crítica, analítica y reflexivamente para ingresar a los argumentos medulares, a las ideas implícitas y explícitas. Se concluye que, lograr aprendizajes significativos y el desarrollo operativo del pensamiento depende del diálogo profundo, riguroso y sensible, de la búsqueda intensa de la verdad y del cuestionamiento sobre la consistencia de los argumentos sobre los que se sustentan los pronunciamientos científicos.

Tropical mountain cloud forests (TMCFs) are characterized by frequent and persistent cloud immersion and fog, resulting in a distinct environment which influences vegetation characteristics and determines ecosystem services. In this chapter we contrast the findings on function at the ecosystem (i.e. forest productivity) and plant (i.e. water and carbon relations) scales in Venezuelan Andean cloud forests with the current state of knowledge for TMCFs, in order to reveal its status, particularly in the context of the Andean forests. Research for the last 70 years on function of Venezuelan cloud forests were evaluated and compared with other TMCFs. Some of this research includes a vast number of studies of limited access available through theses, book chapters and other reports. Venezuelan cloud forests are important ecosystems showing levels of productivity and photosynthetic capacity in the range reported for TMCFs of the Andean region. Results on aboveground biomass were above the average, which could be related to relatively high canopy height, basal area, wood density, and low turnover rates. The reviewed data on ecosystem functioning coincides with recent findings on the importance of TMCFs as carbon stores and potential carbon refuges in the future.

The Andean eco-region of South America is one of the most prominent biodiversity hotspots in the world, which can be attributed to the multiplicity of heterogeneous environments largely driven by a complex of latitudinal and altitudinal gradients. An important feature of this landscape is the presence of the diverse and structurally complex Andean cloud forests (ACFs), which are fundamental in the provision of ecosystem services, mainly linked to water provision and regulation and protection against erosion, ability to absorb and store a substantial amount of carbon in the form of soil organic matter (SOM) and plant biomass, and high levels of biodiversity and endemism. In this chapter, we focus on the Venezuelan Andes to review an important body of work on how these ecosystems function and their current conservation state. We also explore how this accumulated knowledge can provide guidelines for conservation, restoration and adaptation planning. We reviewed ecological studies conducted at different spatial scales, from the landscape to plant levels, to describe the main structural and functional characteristics of the Andean cloud forests in Venezuela. Andean cloud forests in Venezuela are well represented in the protected area system of the country, mainly National Parks. Despite deforestation rates being relatively stable and low (0.1% per year) in recent years, a great proportion of this area is distributed within a mosaic of small fragments (often <10 ha) with strong edge effects from the surrounding grassland matrix. In general, the small forest patches tend to be dominated by species described as early successional colonizers of gaps. Studies of ecosystem processes have shown that replacing forests with pastures limits the ability to regulate water flows, diminishing fog catchment, soil water storage and deep drainage. Long-term forest dynamics studies show how elevation and low temperatures are key drivers of a “slow dynamics” and therefore relatively low turnover rates, also implying a slow rate of recovery from disturbances. Recent investigations on shade tolerance of cloud forest tree species and their associated ecophysiological properties, showed a great potential for the planning of restoration practices based on a functional approach.

Objective To evaluate the individual, social, cultural, health system, and structural barriers related to the human papillomavirus (HPV) in women from eight Latin American countries. Methods A prospective, relational, and analytical study was conducted from July to August 2024 in women from eight Latin American countries: Argentina, Colombia, Mexico, Nicaragua, Peru, Dominican Republic, Uruguay, and Venezuela. Spanish‐speaking adult women who had a history of having undergone cervicovaginal cytology were included. An online survey of 34 items was designed that evaluated the different barriers to HPV medical care. Results Overall, 1930 women were surveyed. There is a lack of education on issues related to sexual and reproductive health, as 57.3% of the participants considered HPV infection to be a sexually transmitted disease. A correlation was observed between a higher level of education and the acceptability of vaccination, as well as the taking of screening tests. It was found that 39.1% were vaccinated, which reflects the lack of resources in hospitals, where the vaccine is not available to all women, a similar situation to the screening test. Conclusion There are still many barriers to HPV medical care due to the cultural roots that exist in the region. It is important to identify them and create strategies that allow equality and accessible medical care for all women, in order to eradicate cervical cancer, which is one of the great pending issues on the gynecologist's agenda.

The aim of this study was to determine a model of relationships to predict the suicidal ideation of school-age adolescents. A model based on the suicidal behavior of peers, the support of the father and mother, family violence, and depression was proposed. The sample consisted of 912 subjects. The results obtained through a path analysis indicate that adolescents with symptoms of depression choose friends with suicidal behaviors, and these, in addition, directly increase the probability of suicidal ideation.

In response to the problems of poor performance of large language models in specific domains, limited research on knowledge graphs and question-answering systems incorporating large language models, this paper proposed a multi-hop question-answering system framework based on a knowledge graph in the medical field, which was fully augmented by large language models (LLM-KGMQA). The method primarily addressed the problems of entity linking and multi-hop knowledge path reasoning. To address the entity linking problem, an entity fast-linking algorithm was proposed, which categorized entities based on multiple attributes. Then, it used user mentions to obtain the target attribute set of attributes and further narrowed the entity search scope through attribute intersection operations. Finally, for entities that remained too numerous after the intersection, the method suggested using a pre-trained model for similarity calculation and ranking, and to determine the final entity through construction instructions. Regarding multi-hop knowledge path reasoning, the paper proposed a three-step reasoning framework that included an n-hop subgraph construction algorithm, a knowledge fusion algorithm, and a semantics-based knowledge pruning algorithm. In the entity fast-linking experiments, the maximum computational complexity was reduced by 99.90% through intersection operations. Additionally, an evaluation metric called CRA@n was used alongside the classic nDCG metric. When using the RoBERTa model for similarity calculations, the CRA@n score reached a maximum of 96.40, the nDCG scores reached a maximum of 99.80, and the entity fast-linking accuracy was 96.60%. In multi-hop knowledge path reasoning, the paper first validated the need for knowledge fusion by constructing three different forms of instructions. Subsequently, experiments were conducted with several large language models, concluded that the GLM4 model showed the best performance in Chinese semantic reasoning. The accuracy rates for GLM4 after pruning were 99.90%, 83.30%, and 86.60% for 1-hop, 2-hop, and 3-hop, respectively, compared to 95.00%, 6.60%, and 5.00% before pruning. The average response time was reduced by 1.36 s, 6.21 s and 27.07 s after pruning compared to before pruning.

The dynamics of a Brownian particle immersed in a bath with variable temperature where both subsystems interact with an external parabolic field are analyzed under the framework of the generalized Langevin equation. This analysis is based on adopting a heuristic method applied to the classical Zwanzig version formulated in 1990 by Brey and Casado. These authors obtained a consistent heat dissipation as a time-dependent temperature external protocol. Including the field-bath interaction, the new dynamic equation retains, in general, the same functional characteristics, with the difference that now the Brownian particle interacts with the external field through an effective frequency modulated by the parameters that characterize the thermal bath. As a consequence, the memory kernel and colored noise are modified by the original field frequency. A method to solve the resulting equation of motion of the Brownian particle is proposed, and the reduced version of its associated Fokker-Planck equation shows that the system would diffuse anomalously, in which the diffusion is a function of time. The solution to the new generalized Langevin equation is analyzed for the average position, and the noise correlation due to the velocity of the Brownian particle for a dedicated heat dissipation model becomes analytic. It is calculated to partially investigate the viability of the equations derived from the theory. From the ensemble-averaged mean-square displacement of the central particle, it is concluded that the process is partially subdiffusive in the time considered in the calculation. Published by the American Physical Society 2025

Introduction The advances and studies carried out in the area have shown that patients with aortic stenosis (AS) undergoing surgical valve replacement (SAVR) did not have encouraging outcomes. This study aims to compare the different risk factors in patients with AS undergoing transcatheter aortic valve replacement (TAVR) vs. SAVR, respectively, to offer options and more favorable results based on the results obtained in patients with these conditions. Methods The study was in accordance with the PRISMA guidelines. Studies comparing outcomes of surgical and transaortic catheter valve replacements in adults were included. Descriptive statistics, binary random effects, and continuous random effects were used. I ² statistics were used to assess for heterogeneity. A P -value ≤0.05 was considered statistically significant. Results In total, eight studies with 18 671 patients were included in our study. All-cause mortality (2.48% vs. 3.03%), major bleeding (11.25% vs. 31.05%), and atrial fibrillation (2.39% vs. 50.42%) were lower in TAVR compared to SAVR. Furthermore, odds of all-cause mortality (odds ratio [OR]: 0.79; 95% CI: 0.63–1.00; P = 0.05), stroke (OR: 0.71; 95% CI: 0.58–0.87; P = 0.0008), and acute kidney injury (AKI) (OR: 0.38; 95% CI: 0.29–0.49; P < 0.00001) were lower in the TAVR group compared to the SAVR group. Conclusion TAVR is superior to SAVR and significantly reduces the risks associated with all-cause mortality, stroke, AKI, and other clinical outcomes. Furthermore, additional research is regarding the long-term effects of transcatheter aortic valve replacement.

Understanding the role of pressure anisotropy and dissipation is crucial for modelling compact objects’ internal structure and observable properties. In this work, we reinterpret local pressure anisotropy in relativistic stellar structures as an additional contribution to the energy density. This perspective enables the formulation of anisotropic equations of state for self-gravitating systems by incorporating anisotropy as a fundamental component. We demonstrate that this approach yields more realistic stellar models that satisfy key physical constraints, including mass-radius relationships and stability conditions. Our results are compared with observational data, particularly the inferred compactness of pulsars PSR J0740+6620 and PSR J0030+0451, showing that both anisotropic and isotropic models can describe these objects. Additionally, we examine the influence of dissipation – such as temperature gradients – on radial pressure, demonstrating that it can be modelled similarly to anisotropy. This interpretation allows the transformation of dissipative anisotropic models into equivalent non-dissipative isotropic configurations.

Bacterial inoculation stimulates growth and adaptation in micropropagated plants. This study evaluated the effects of biotization on in vitro seedling production and in vivo adaptation in two potato cultivars, Agatha and Duvira. Nine bacterial strains were tested for hormone production and ACC deaminase activity and then inoculated in vitro and re-inoculated in vivo. Growth, adaptation, and tuber production were assessed. Biotization significantly enhanced seedling growth, survival, and tuber yield. Biotized seedlings had a 1.3-fold higher survival rate than the controls. Azospirillum brasilense Ab-V5 and Rhizobium tropici CIAT 899 promoted at least one growth variable in both cultivars under in vitro and in vivo conditions. A. brasilense Ab-V5 consistently improved plant performance across production stages, with re-inoculated plants showing 1.2–1.3-fold increases in stem and root length and a 1.1-fold gain in total dry biomass. Additionally, inoculated plants produced 1.9 times more tubers than the controls. Biotization effects were strain-dependent, with A. brasilense Ab-V5 improving in vitro seedling quality and enhancing plant performance and survivability in vivo.

This review considers a profoundly underutilized resource, technical lignin, and its potential for large scale upgrading for higher-valued industrial usage by means of self-assembly processes. Molecular interactions that can be used to guide lignin self-assembly are systematically explored, categorizing them into physicochemical interaction-driven assembly and external stimuli or template-driven assembly. Published findings are examined to reveal molecular mechanisms governing lignin aggregation into lignin nanoparticles (LNPs), films, and interfacial behavior in Pickering emulsions that have potential to be used industrially. Recent advancements in experimental techniques are explored to provide deeper insights into lignin's self-assembly processes. Hydrophobic effects, π-π stacking, hydrogen bonding, electrostatic layering, polyelectrolyte complex formation, chain entanglement, and covalent cross-linking are critically assessed as potential means to control the self-assembly of lignin and systems involving lignin. Additionally, external factors, such as chemical dehydration, solvent-mediated interactions, and external fields are examined related to their role in templating lignin assembly. Based on a comprehensive review of the literature, hydrophobic interactions are predominant in lignin aggregation, with hydrophobicity degrees varying significantly across lignin samples. Interfacial rheology studies demonstrate that lignosulfonate exhibits maximum storage moduli at oil-water interfaces, significantly enhancing emulsion stability. Additionally, modified lignins via esterification contribute larger lifetimes of water-in-oil emulsions stability under varying salinity and oil types. The integration of molecular modeling with experimental characterization techniques can further optimize lignin-based materials for multiple applications, such as drug delivery, catalysis, advanced pesticide delivery systems, bioplastics, 3D printing, and emulsification, among many others. Although there are existing technical and economic assessments (TEA) and life cycle assessments (LCA) involving lignin self-assembly that point to promising prospects, there is a need for more comprehensive TEA and LCA work to clear the way for the needed industrial innovations in this field.

The genus Capsicum includes economically important species important species, widely used as food and condiment. A critical stage of its production is obtaining quality seedlings, better adapted to transplanting, vegetative and productive development. The use of plant growth-promoting rhizobacteria (PGPR) in the production of high-quality vegetable seedlings can contribute to a more efficient agriculture, less dependent on crop protection products and mineral fertilizers. Therefore, the aim of this study was to select PGPR from pepper plants in the Brazilian Amazon savanna, using the quality index (QI) as a selection criterion and to evaluate their ability to produce promoters of plant growth, such as indole-3-acetic acid (IAA), phosphate solubilization (SCa-P), and biological nitrogen fixation (BNF). The experiment was conducted in Randomized Block Design (RBD) with four replications and 139 treatments, including a positive control (PC) and a negative control (NC). The ten best isolates were identified molecularly and subjected to three biochemical tests. The ten best bacteria demonstrated high growth promotion of pepper seedlings in the in vivo tests. Although not all isolates in this group demonstrated SCa-P and BNF capabilities, all of the isolates produced IAA. The bacteria isolated from the rhizosphere promoted the production of seedlings with higher QI, but the selection of bacteria based solely on the production of IAA, SCa-P, and BNF in vitro may not be enough to find the best isolates for promoting growth in pepper seedlings, as not all exhibited these mechanisms even though they improved the quality index (QI) of the seedlings.

Objective: This study aimed to evaluate the intestinal microbiota development in the first week of life of preterm newborns (PTNB) treated at a public hospital in a municipality in the Brazilian Northeast. Methods: This is an observational, longitudinal, and descriptive study with 23 PTNBs. Two stool samples were collected from each neonate (fasting/meconium and seventh day of life) for stool microbiota analysis by 16S rRNA gene sequencing. The authors analyzed alpha diversity (Chao1, Shannon, and Simpson indices) and principal coordinates of beta diversity. Results: Forty-six stool samples from 23 PTNBs were analyzed at the taxonomic level. Microbiota's development was dynamic with low diversity. The authors observed a statistical association with the genera Enterobacterales, Streptococcus, Bacteroides, Clostridium_sensu_stricto_1, Enterococcus, and Bifidobacterium in the fasting samples when compared to the day-7 samples. The genus Staphylococcus also dominated at both times. Conclusion: Dynamics were observed in the intestinal microbiota development, with an alpha diversity decrease in the stool samples collected at fasting/meconium and on the seventh day of life.