Producción científica y académica

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Detection of bisphenol a and four analogues in atmospheric emissions in petrochemical complexes producing polypropylene in South America

Hernández Fernández, Joaquín | 2022-07-28

Because of its toxicity and impacts on the environment and human health, bisphenol A (BPA) has been controlled in numerous industrialized nations, increasing demand for bisphenol analogues (BP) for its replacement. However, the consequences of these chemicals on the environment and the health of persons exposed to their emissions are still being researched. The emissions from polypropylene manufacturing facilities in Colombia and Brazil were evaluated in this study, and the presence of bisphenol A and four BPs was detected among the gaseous compounds released, with total concentrations of BPs (∑BP) between 92 and 1565 ng g−1. As the melt flow index (MFI) of the polymer rises, so does the quantity of volatiles in its matrix that are eliminated during deodorization, indicating that the MFI and the amount of bisphenol released have a directly proportional connection.

Granular subbase improvement with recycled concrete aggregates in tropical areas

Vega Araujo, Daniela | 2022

Use of Recycled Concrete Aggregate (RCA) for Granular Subbase (GSB) in the tropical area is evaluated in this work. Among the materials widely studied as replacements in granular and surface layers is RCA. Its mechanical behavior in granular layers has mainly been evaluated with tests such as California Bearing Ratio (CBR). However, abrasion is also a determining property in the strength of these materials. In this study, the performance of Natural Aggregates (NA) with replacement of RCA was evaluated for use as GSB in a tropical area. Even though several laboratory tests were performed, the focus of the article lies on the performance in the Los Angeles (LA) abrasion test. Two replacement percentages of coarse RCA were considered: 10 and 15 % by weight of aggregates. The RCA and NA were characterized according to different laboratory tests: Granulometry, Absorption, Atterberg Limits test, Plasticity, Specific Gravity, and LA abrasion. In turn, all results were compared with Colombian specifications for a typical GSB in the area. In addition, a simple Life Cycle Assessment (LCA) was included to evaluate the environmental impacts of the base and alternative scenarios. The results show that GSB with 10% RCA present a higher abrasion resistance than the GSB with 15% RCA. Even better results are obtained with 10% RCA than with natural GSB. Specifically, average LA abrasion test losses of 30.86, 29.80 and 32.07% were obtained for NA, 10% RCA and 15% RCA, respectively. The LCA results show an increase of 50% and 75% in energy consumption by comparing the base scenario with 10 and 15% RCA replacement, respectively. This leads to an increase of 40 and 80% in carbon monoxide (CO) emissions for 10 and 15% RCA replacement respectively, and 100% in carbon dioxide (CO2) emissions for both alternative scenarios.

Identification and quantification of microplastics in effluents of wastewater treatment plant by differential scanning calorimetry (DSC)

Hernández Fernández, Joaquín | 2022-04-20

In this research, the presence of microplastics was detected through a differential scanning calorimetry (DSC) analysis of three wastewater treatment plants. One of these plants applied only a preliminary treatment stage while the others applied up to a secondary treatment stage to evaluate their effectiveness. The results showed the presence of polyethylene (PE), polystyrene (PS), polypropylene (PP) and polyethylene terephthalate (PET), which were classified as fragments, fibers or granules. During the evaluation of the plants, it was determined that the preliminary treatment did not remove more than 58% of the microplastics, while the plants applying up to a secondary treatment with activated sludge achieved microplastic removal effectiveness between 90% and 96.9%.

Impact of acute blood loss on clinical, hematological, biochemical, and oxidative stress variables in sheep

Santos Sousa, Rejane | 2022-05-11

Blood loss in sheep can have different causes and may result in anemia. We aimed to evaluate the clinical, hematological, and biochemical alterations and the oxidative stress generated by acute blood loss. Eighteen healthy sheep underwent phlebotomy to remove 40% of the blood volume and were evaluated clinically and by laboratory tests for clinical, biochemical, and blood gas variables and to assess oxidative stress before induction (T0), 30 min (T30 min), and 6 (T6 h), 12 (T12 h), and 24 h (T24 h) after blood loss. The sheep showed tachycardia from T30 min until T24 h, reduction in the hematocrit, number of erythrocytes, and hemoglobin concentration, with lower values at T24 h and increase in the number of leukocytes from T12 h on. There was a reduction in blood pH and oxygen pressure at T30 min, increased lactate concentration and reduced blood bicarbonate at this time. There was an increase in urea concentration from T6 h until the end of the study, with no change in creatinine levels. The animals did not show changes in the concentration of malonaldehyde, and in the activity of the enzymes superoxide dismutase, glutathione peroxidase, and catalase, but there was a reduction in the concentration of reduced glutathione at T24 h. The acute loss of 40% of blood volume is capable of promoting relevant clinical, hematological, blood gas, and biochemical alterations, and contributed to the appearance of oxidative stress with reduced glutathione concentration, suggesting that this process generated free radicals in sufficient quantity to diminish the action of antioxidants.

Impact of mobility restrictions on the dynamics of transmission of COVID-19 in Colombian cities

Paternina-Caicedo, Angel | 2022

Our aim was to study the association between case rates and reductions in urban mobility in state capitals of Colombia. We designed an ecological time-series study to correlate the Colombian incidence rate with reductions in mobility trends of retail stores. The meta-analysis of β coefficients describing the association between case rates and reductions in mobility trends of retail stores resulted in a mean estimate of 0.0637 (95% confidence interval 0.027 to 0.101; p<0.001) with nearly 100% heterogeneity. We recommend continuing to consider mobility restrictions when the number of cases starts to climb in each local jurisdiction.

Impact of quarantine due to COVID-19 pandemic on health and lifestyle conditions in older adults from Centro American countries

Mendoza Ruvalcaba, Neyda Ma | 2022-05-11

The impact of quarantine in older adults have been reported in several studies with contradictory results, reporting from negative effects to no significant outcomes or even beneficial consequences. Heterogeneity in aging plays a role in each region, the aim of this study is to analyze the impact of quarantine on health conditions (physical and mental) and lifestyle in older adults in five Centro American countries during COVID-19 pandemic. In this cross-sectional study, n = 712 older adults 60 years and older from Mexico, Guatemala, El Salvador, Honduras and Costa Rica were assessed by telephone. Sociodemographic data, physical and mental health, lifestyle and quarantine conditions were asked previous informed consent. In general, mean of days in quarantine at the moment of the study was 142 days (approximately four months and three weeks). In the analysis of the impact of the days in quarantine effects were found on the frequency of falls, functional ability in Activities of Daily Living (ADL), general cognitive function, memory, orientation, language, frequency of drinking alcohol, having a balanced diet, and being active cognitively. Some differences were found between countries. Effects of quarantine on older adults in Centro America, requires attention of governments and healthcare to prevent long term morbidity and disability, and to promote healthy aging.

Multinomial cross-sectional regression models to estimate and predict the determinants of academic performance: the case of auditor accountant of the Pontifical Catholic University of Valparaíso

de la Fuente-Mella, Hanns | 2022-07-28

The debate on the primary cross-curricular skills or fundamental competencies that must be improved in higher education has increased in the last few years. This is especially important in the new distant learning environments, which bring new challenges to the educational process. Econometric models have been designed to explain the students’ academic performance, which has been measured using their qualifications average, the number of failed subjects, passed subjects, and withdrawn subjects, and the level of progress, among other indicators, to try to understand the influence of variables such as students’ self-esteem, reading comprehension, English proficiency level, and performance in a mathematics-related subject on the students of accountant auditor program from Pontificia Universidad Católica de Valparaiso. Students were asked to fill in a questionnaire to collect data on the psychological and pedagogical variables, while the socio-economic and socio-demographic data were collected from the university. The results have shown that the most significant variables in the development level of this skill type are socio-demographic and socio-economic characteristics. Some of the psychological and pedagogical variables that have, to a lesser degree, some influences are self-regulation in the learning process and the self-perception of anxiety levels. Lastly, some recommendations to intervene in the students’ learning process are presented with the objective of achieving a higher level of development in this type of competences.

Optimizing the multi-level location-assignment problem in queue networks using a multi-objective optimization approach

Syah, Rahmad | 2022

Using hubs in distribution networks is an efficient approach. In this paper, a model for the location-allocation problem is designed within the framework of the queuing network in which services have several levels, and customers must go through these levels to complete the service. The purpose of the model is to locate an appropriate number of facilities among potential locations and allocate customers. The model is presented as a multi-objective nonlinear mixed-integer programming model. The objective functions include the summation of the customer and the waiting time in the system and the waiting time in the system and minimizing the maximum possibility of unemployment in the facility. To solve the model, the technique of accurate solution of the epsilon constraint method is used for multi-objective optimization, and Pareto solutions of the problem will be calculated. Moreover, the sensitivity analysis of the problem is performed, and the results demonstrate sensitivity to customer demand rate. Based on the results obtained, it can be concluded that the proposed model is able to greatly summate the customer and the waiting time in the system and reduce the maximum probability of unemployment at several levels of all facilities. The model can also be further developed by choosing vehicles for each customer.

Increasing the efficiency of a control system for detecting the type and amount of oil product passing through pipelines based on gamma-ray attenuation, time domain feature extraction, and artificial neural networks

Mayet, Abdulilah | 2022-07-13

Instantaneously determining the type and amount of oil product passing through pipelines is one of the most critical operations in the oil, polymer and petrochemical industries. In this research, a detection system is proposed in order to monitor oil pipelines. The system uses a dual-energy gamma source of americium-241 and barium-133, a test pipe, and a NaI detector. This structure is implemented in the Monte Carlo N Particle (MCNP) code. It should be noted that the results of this simulation have been validated with a laboratory structure. In the test pipe, four oil products—ethylene glycol, crude oil, gasoil, and gasoline—were simulated two by two at various volume percentages. After receiving the signal from the detector, the feature extraction operation was started in order to provide suitable inputs for training the neural network. Four time characteristics—variance, fourth order moment, skewness, and kurtosis—were extracted from the received signal and used as the inputs of four Radial Basis Function (RBF) neural networks. The implemented neural networks were able to predict the volume ratio of each product with great accuracy. High accuracy, low cost in implementing the proposed system, and lower computational cost than previous detection methods are among the advantages of this research that increases its applicability in the oil industry. It is worth mentioning that although the presented system in this study is for monitoring of petroleum fluids, it can be easily used for other types of fluids such as polymeric fluids.

Nuevos enfoques en derechos humanos, irenología y métodos de solución de conflictos

ARRIETA-LÓPEZ, Milton | 2022

El objeto de la presente publicación consiste en ofrecer reflexiones científicas sobre los progresos en nuevos enfoques doctrinarios los cuales sirvan de base para analizar la situación actual, así como diversas perspectivas en los derechos humanos, la irenología y los métodos de solución de conflictos. Los problemas respecto a las temáticas planteadas usualmente abordados desde el dualismo reduccionista de lo que es y lo que debe ser, en la presente obra son extendidos a partir del análisis científico e interdisciplinario, y sustentado en diversas perspectivas de abordaje a las problemáticas sociales para interpretarlas y darles solución en la mecánica y funcionamiento de nuevas situaciones y realidades emergentes. Esta obra ha sido edificada de forma colectiva y gira en torno a tres ejes temáticos conexos, los cuales son los derechos humanos, la irenología y los métodos de solución de conflictos, cada eje temático se encuentra construido por tres capítulos en los que trabajaron diecisiete investigadores adscritos a la Universidad Autónoma de Nuevo León de México, la Universidad Autónoma de Coahuila de México, la Universidad de la Costa de Colombia y la Universidad Rey Juan Carlos de España.

Determinants of open innovation in low-tech SMEs: the influence of the top management team and employees’ human capital

VEGA-JURADO, JAIDER | 2022

This article aims to analyze the influence of top management team (TMT) characteristics and employees’ human capital on the adoption of open innovation practices in low-tech SMEs. The empirical study is based on the use of structural equations from the data derived from a questionnaire applied to 95 companies in the agro-industrial sector located in the northeastern region of Colombia. The results indicate that both the TMT’s diversity and coordination have a significant and positive influence on the adoption of open innovation practices. On the other hand, regarding human capital, the results indicate that the experience of the employees is a more decisive feature when implementing open innovation strategies than their level of education and training. This paper contributes to the literature by providing part of the missing microfoundations of open innovation and more strongly connecting open innovation, human capital, and TMT configuration.

A new class of degenerate Apostol-type Hermite polynomials and applications

Cesarano, Clemente | 2022-04

In this article, a new class of the degenerate Apostol–type Hermite polynomials is introduced. Certain algebraic and differential properties of there polynomials are derived. Most of the results are proved by using generating function methods.

Weakly ω-continuous functions in bitopological spaces

Carpintero, C. | 2022

In this paper, as a generalization of u-ω-continuous functions, we introduce the notion of weakly ω-continuous functions in bitopological spaces and obtain several characterizations and some of its properties.

Behavioural, odontological and physical activity patterns of hypertense and control population

Carreira Míguez, María | 2022-08-01

Behavioural and multifactorial factors such as odontological and physical activity habits are controlling factors in hypertension. The aim of the present study was to analyze differences in behavioral, odontological and physical activity patterns of hypertense and control population. Fifty participants with hypertension (57.5±13.6 years) and 100 participants as control group with no hypertension disease (48.9±7.9 years) were interviewed via online questionnaire. Multifactorial items in oral behavioral, health habits and physical activity profile were analyzed by a compendium of questionnaires. Result showed how control group showed significantly lower age, weight, body mass index, TV hours per day, gastritis or heartburn, dental sensibility, and sick days last year, and significantly higher level of academic education, quality of sleep and daily toothbrushing than hypertension group. In conclusion our results showed that hypertense patients presented higher levels of overweight, poor sleep quality and sedentary behaviors than control participants. In addition, hypertense patients also presented poor odontological health, showing higher indices of gastritis, dental sensibility, and sick days per year. Both groups presented a low physical activity pattern. This information allows to better understand of a multifactorial disease, as well to the creation of protocols for intervention and prevention of this disease at the behavioral level and lifestyle

Determinants of open innovation in low-tech SMEs: the influence of the top management team and employees' human capital

VEGA-JURADO, JAIDER | 2022-04-24

This article aims to analyze the influence of top management team (TMT) characteristics and employees’ human capital on the adoption of open innovation practices in low-tech SMEs. The empirical study is based on the use of structural equations from the data derived from a questionnaire applied to 95 companies in the agro-industrial sector located in the northeastern region of Colombia. The results indicate that both the TMT’s diversity and coordination have a significant and positive influence on the adoption of open innovation practices. On the other hand, regarding human capital, the results indicate that the experience of the employees is a more decisive feature when implementing open innovation strategies than their level of education and training. This paper contributes to the literature by providing part of the missing microfoundations of open innovation and more strongly connecting open innovation, human capital, and TMT configuration.

Factores intervinientes en el proceso de costeo del sector maderero del departamento del Chocó

Mayo Ríos, Mayiris | 2020-04-13

El artículo estuvo dirigido a identificar los factores intervinientes en el proceso de costeo del sector maderero del Departamento del Chocó. Se tipifica con una metodología descriptiva, bajo un diseño no experimental, transeccional y de campo. La población estuvo conformada por 50 participantes con inherencia al manejo contable de las empresas del sector maderero. La recolección de datos se llevó a cabo mediante la observación por encuesta, en escala tipo Likert. Se evidenciaron características de internas y externas de las organizaciones del sector y su influencia en la eficiencia del proceso productivo.

Propiedades psicométricas del GAD-7 para detectar ansiedad generalizada en profesionales sanitarios de Bolivia

Porto, María F. | 2022

El aumento de los casos y las muertes relacionadas con la COVID-19 ha generado un importante desgaste físico y emocional en los profesionales sanitarios. El personal de salud ha tenido que enfrentarse al estigma y al rechazo social, al riesgo a enfermar y al miedo a contagiar a sus familias, lo que podría disminuir su bienestar psicológico y aumentar los problemas de salud mental (1). La ansiedad generalizada es un trastorno mental en el cual una persona está preocupada o ansiosa respecto de una o varias situaciones y le parece difícil controlar sus síntomas. La evidencia disponible muestra un incremento de la ansiedad generalizada en el personal médi co que está en contacto directo con los pacientes contagiados con la COVID-19 (2). Durante la pandemia, la carga global de ansiedad en los trabajadores de la salud se incrementó en más del 30% (3). Por tanto, el uso de instrumentos breves, fáciles de aplicar y capaces de detectar alteraciones psicológicas en la actual pandemia, ha tomado relevancia (4). La escala de ansiedad de siete ítems (GAD-7) (Material suplementario), se desarrolló originalmente en inglés como una herramienta de detección breve capaz de detectar la ansiedad (5). El estudio original reportó adecuados valores de sensibilidad (0,92) y especificidad (0,83). Desde entonces, sus propiedades psicométricas se han examinado (6). En Latinoamérica se reportan estudios en Perú (7) y Colombia (8). Sin embargo, no existen datos publicados en Bolivia sobre las características psicométricas de este instrumento. Por lo tanto, analizamos las propiedades psicométricas del GAD-7 en una muestra amplia de profesionales sanitarios bolivianos durante la pandemia de la COVID-19.

¿Por qué delinquen las mujeres?: enfoque de género en la conducta delictiva, contexto penitenciario y tratamiento

Charris-Peláez, Valentina Maried | 2022-01

La delincuencia es un fenómeno complejo que permea y afecta profundamente nuestra sociedad. A pesar de que existen innumerables estudios sobre la conducta delictiva, las investigaciones han dejado a un lado la variable de género, la cual marca una diferencia importante en la explicación de las conductas humanas. Esto genera no solo vacíos teóricos, sino también dificultades en la comprensión, explicación y posible solución de este fenómeno. Por ello se realizó una revisión bibliográfica entorno a las diferencias de género en la conducta delictiva, contexto penitenciario y tratamiento para la reinserción social, donde se logró identificar 59 artículos seleccionados de las principales bases de datos científicas, durante el periodo 2000-2020. Se encontró que las mujeres que cometen actos delictivos deben ser sujetas a un tratamiento particular, diseñado en función de las características particulares de su perfil criminal y de las necesidades especiales que su propio género exige. Lo anterior implica un abordaje multicausal y multidisciplinar que dirija el desarrollo de programas que logren atender a esta población de una manera pertinente y eficaz.

Inventory models in a sustainable supply chain: a bibliometric analysis

Salas-Navarro, Katherinne | 2022-05-15

This paper presents a bibliometric analysis of inventory models in a sustainable supply chain. The methodology contains reviewing previous research with a performance evaluation, network analysis, and science mapping to identify the applications, trends, and future research topics. Scientific mapping examines the periods and volumes of publications, authors, journals, countries, regions, organizations, subject areas, and citation analyses. The dataset was obtained with the Scopus database and analyzed using MS Excel and VOSviewer. The search equation identified 335 research papers, which resulted in 131 significant manuscripts on the subject after being screened and filtered. The most notable countries in developing research were Iran, India, China, the United States, Canada, Taiwan, France, the United Arab Emirates, Turkey, and Denmark. Saha, S., Ajay, S.Y., and Baboli, A. were the most cited authors. The journals that publish the most research were Sustainability, the Journal of Cleaner Production, and the International Journal of Production Economics. Some research focuses on reducing carbon emissions and polluting agents applied in different industries in China, Brazil, India, and others. The main findings were the number of industry sectors researching this topic, increasing the number of publications, and promoting the proper use of resources within a sustainable supply chain. There are many investigations of theoretical models that have applications in real-life cases. There is also evidence of the high importance of promoting sustainable development. The emissions regulations in a green supply chain applied to agricultural products have allowed for more actions to achieve responsible production and consumption, as seen in applied research in the pulp and paper industry.

Leaching of rare earth elements from phosphogypsum

Frantz Lütke, Sabrina | 2022

High amounts of phosphogypsum (PG) are generated in the production of phosphoric acid. Previous literature demonstrates that obtaining rare earth elements (REE) from PG is a promising alternative to managing this waste. However, the reported leaching efficiencies are low in most cases, or drastic leaching conditions are required. Therefore, this work aimed to study the leaching conditions of REE from PG to obtain high leaching efficiency values. Initially, a 24 factorial experimental design investigated the factors that affect the conventional acid leaching of REE from PG (leaching acid (citric and sulfuric acid), solid/liquid ratio, acid concentration, and temperature). Better leaching efficiency values of the sum of all REE (62.0% and 89.7% for citric and sulfuric acid, respectively) were obtained using an acid concentration of 3 mol L−1, solid/liquid ratio of 1/20 g mL−1, and temperature of 80 °C. Subsequently, the experiments optimization, performed through a central composite rotational design, indicated that the maximum leaching efficiency was achieved using a sulfuric acid concentration of 2.9 mol L−1, solid/liquid ratio of 1.7/20 g mL−1, and 55 °C. Under these conditions, the leaching efficiency of the sum of all REE was 90.0%. Leaching kinetics results showed that the equilibrium was reached in about 20 min for most REE. The mechanism investigation suggested that surface chemical reaction and diffusion through the boundary layer controlled the leaching.