Now showing items 5525-5544 of 7745

N-Ribosyltransferase From Archaeoglobus veneficus: A Novel Halotolerant and Thermostable Biocatalyst for the Synthesis of Purine Ribonucleoside Analogs

Acosta, Javier; Del Arco, Jon; Pisabarro, Victor; Gago, Federico; Fernández-Lucas, Jesús (Frontiers in Bioengineering and Biotechnology, 2020-06-20)

Nucleoside-2′-deoxyribosyl-transferases (NDTs) catalyze a transglycosylation reaction consisting of the exchange of the 2′-deoxyribose moiety between a purine and/or pyrimidine nucleoside and a purine and/or pyrimidine ...
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Gúzman Villareal, Lilian (Universidad de la Costa, 2020)

Manuscrito ganador del primer lugar del III concurso de microcuento. Microcuento de suspenso, que cuestiona la percepción de la realidad.
Nanometric particles of high economic value in coal fire region: Opportunities for social improvement

Silva Oliveira, Luis Felipe; Crissien Borrero, Tito José; Schneider, Ismael L.; Blanco, Érika P.; Sampaio, Carlos H. (Universidad de la Costa, 2020-02-10)

Spontaneous coal combustion in the La Guajira coals was studied for the presence of carbon nanophases (e.g., carbon nanotubes), occurrence of rare earth elements (REEs) in them, and the probable mechanisms for concentration ...
Nanomineralogy of evaporative precipitation of efflorescent compounds from coal mine drainage

O. Silva, Luis F.; Pinto, Diana; Dotto, Guilherme Luiz; Hower, James (Universidad de la Costa, 2020)

Efflorescent nanophases (NPs) are found as a transitory accumulation of potentially hazardous elements (PHEs), particularly in tropical climates. The central objective of this study was to investigate the distribution of ...
Nanomineralogy of mortars and ceramics from the Forum of Caesar and Nerva (Rome, Italy): The protagonist of black crusts produced on historic buildings

Oliveira S., Marcos L; Flores, Erico; Dotto, Guilherme Luiz; Neckel, Alcindo; Silva O., Luis F. (Corporación Universidad de la Costa, 2021)

The recent focus of the impacts of atmospheric pollution on effective conservation methods for historic structures of great cultural heritage has been shown to be of critical importance for preservation. This work focuses ...
Nanomineralogy of mortars and ceramics from the Forum of Caesar and Nerva (Rome, Italy): the protagonist of black crusts produced on historic buildings

Silva Oliveira, Marcos Leandro; Flores, Erico; Dotto, Guilherme Luiz; Neckel, Alcindo; Silva Oliveira, Luis Felipe (Corporación Universidad de la Costa, 2021)

The recent focus of the impacts of atmospheric pollution on effective conservation methods for historic structures of great cultural heritage has been shown to be of critical importance for preservation. This work focuses ...
Nanominerals and potentially hazardous elements from coal cleaning rejects of abandoned mines: Environmental impact and risk assessment

Fdez Ortiz De Vallejuelo, Silvia; Gredilla, Ainara; Da Boit Martinello, Katia; Calesso Teixeira, Elba; Sampaio Hoffmann, Carlos; Madariaga, Juan Manuel; Silva Oliveira, Luis Felipe (Universidad de la Costa, 2017)

Soils around coal mining are important reservoir of hazardous elements (HEs), nanominerals, and ultrafine compounds. This research reports and discusses the soil concentrations of HEs (As, Cd, Cr, Cu, Ni, Pb, and Zn) in ...
Nanominerals and potentially hazardous elements from coal cleaning rejects of abandoned mines: Environmental impact and risk assessment

Fdez Ortiz De Vallejuelo, Silvia; Gredilla, Ainara; Da Boit Martinello, Katia; Calesso Teixeira, Elba; Sampaio, Carlos Hoffmann; Madariaga, Juan Manuel; Silva Oliveira, Luis Felipe (Chemosphere, 2017)

Soils around coal mining are important reservoir of hazardous elements (HEs), nanominerals, and ultrafine compounds. This research reports and discusses the soil concentrations of HEs (As, Cd, Cr, Cu, Ni, Pb, and Zn) in ...
Nanominerals assemblages and hazardous elements assessment in phosphogypsum from an abandoned phosphate fertilizer industry

Frantz Lütke, Sabrina; Silva Oliveira, Marcos Leandro; Silva Oliveira, Luis Felipe; Cadaval Jr., Tito R. S.; Dotto, Guilherme Luiz (Universidad de la Costa, 2020)

The present work investigates hazardous elements and nanomineralogical assemblages of phosphogypsum waste from an abandoned phosphate fertilizer industry located in Santa Catarina state (Brazil). Correlations between the ...
Nanoparticles and interfaces with toxic elements in fluvial suspended sediment

Silva Oliveira, Luis Felipe; Dotto, Guilherme Luiz; Pinto, Diana; Silva Oliveira, Marcos Leandro (Universidad de la Costa, 2021)

Studies examining nanoparticles (NPs) and hazardous elements (HEs) contained in suspended sediments (SSs) are vital for watershed administration and ecological impact evaluation. The biochemical consequence of titanium-n ...
Nanoparticles as vectors of other contaminants in estuarine suspended sediments: natural and real conditions

Silva Oliveira, Marcos Leandro; Dotto, Guilherme Luiz; Pinto, Diana; Neckel, Alcindo; Silva Oliveira, Luis Felipe (Corporación Universidad de la Costa, 2021)

Studding the behaviour and danger of nanoparticles (NPs, minerals and amorphous phases) in the estuarine ecosystem is presently incomplete by the lack of measureable description of NPs in the ecological conditions, such ...
Nanoparticles from construction wastes: A problem to health and the environment

L.S. Oliveira, Marcos; Izquierdo, Maria; Querol, Xavier; Lieberman, Roy N.; K. Saikia, Binoy; F.O. Silva, Luis (Universidad de la Costa, 2019-02-08)

The present study deals with the nano-mineralogy and geochemistry of ultrafine particles in construction waste from the Porto Alegre region in Southern Brazil. Uncontrolled construction waste dumps and poor management ...
Nanoparticles from evaporite materials in Colombian coal mine drainages

Silva Oliveira, Luis Felipe; Hower, James C.; Dotto, Guilherme Luiz; Silva Oliveira, Marcos Leandro; Moreno, Andrea L. (Corporación Universidad de la Costa, 2020)

Ultrathin and nanometric materials (minerals and amorphous phases) are detected in transitory deposits of potential hazardous elements (PHEs), especially in acidic coal mine drainages. The main goal of this work was to ...
Nanoparticles generated during volcanic rock exploitation: an overview

Gindri Ramos, Claudete; Silva Oliveira, Marcos Leandro; Fernández Pena, Merlys; Meriño Cantillo, Andrea; Lozano Ayarza, Liliana Patricia; Korchagin, Jackson; Campanhola Bortoluzzi, Edson (Corporación Universidad de la Costa, 2021)

Nanoparticles (NPs) from the mining of volcanic rocks have been a matter of concern around the world because they can pose environmental and human health risks. The nanoparticles are pointed as opportunities of application ...
Nanoparticles in fossil and mineral fuel sectors and their impact on environment and human health: A review and perspective

Silva Oliveira, Luis Felipe; Santosh, M; Schindler, Michael; Gasparotto, Juciano; Dotto, Guilherme Luiz; S. Oliveira, Marcos L.; Hochella, Jr. (Corporación Universidad de la Costa, 2021)

Nanoscience and technology have enabled better insights into the environmental and health impacts arising from the mining, production and use of fossil and mineral fuels. Here we provide an overview of the nanoscience-based ...
La narración como mediación didáctica en la comprensión lectora de estudiantes de tercer grado de básica primaria

Meléndez Mendoza, Mauricio (Corporación Universidad de la CostaMaestría en Educación, 2021)

The research objective was to determine the effect of narration as a didactic mediation in reading comprehension in third grade students of elementary school, basing in a positivist paradigm. The type of research was ...
Natural ester fluids applications in transformers as a sustainable dielectric and coolant

Hernández Herrera, Hernan; Silva Ortega, Jorge I; Mejia-Taboada, Mario; Diaz Jacome, Alfredo; Torregroza-Rosas, Melissa (Corporación Universidad de la Costa, 2019)

New requirements for a better sustainable energy policy around the world is easy to observe, many projects in sustainable energy are developed wherein the academia works together the authorities and commercial firms such ...
Natural language explanation model for decision trees

Silva, Jesús; H, H; Núñez, Vladimir; Ruiz Lázaro, Alex; Varela Izquierdo, Noel (Journal of Physics: Conference Series, 2020-02-01)

This study describes a model of explanations in natural language for classification decision trees. The explanations include global aspects of the classifier and local aspects of the classification of a particular instance. ...
Naturally growing grimmiaceae family mosses as passive biomonitors of heavy metals pollution in urban-industrial atmospheres from the Bilbao Metropolitan area

Gallego-Cartagena, Euler; MORILLAS, HECTOR; Carrero Carrero, Antonio José; Madariaga, Juan Manuel; Maguregui, Maite (Corporación Universidad de la Costa, 2021)

In analytical chemistry, biomonitoring is known as the methodology, which consider the use of living organisms to monitor and assess the impact of different contaminants in a known area. This type of monitoring is a ...
Near ω-continuous multifunctions on bitopological spaces

Rosas, E.; Carpintero, C.; Rajesh, N.; Shanthi, S. (Universidad de la Costa, 2019-10)

In this paper, we introduce and study basic characterizations, several properties of upper (lower) nearly (i; j)-!-continuous multifunctions on bitopological space.

Envíos recientes

N-Ribosyltransferase From Archaeoglobus veneficus: A Novel Halotolerant and Thermostable Biocatalyst for the Synthesis of Purine Ribonucleoside Analogs
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Acosta, Javier | 2020-06-20

Nucleoside-2′-deoxyribosyl-transferases (NDTs) catalyze a transglycosylation reaction consisting of the exchange of the 2′-deoxyribose moiety between a purine and/or pyrimidine nucleoside and a purine and/or pyrimidine base. Because NDTs are highly specific for 2′-deoxyribonucleosides they generally display poor activity on modified C2′ and C3′ nucleosides and this limitation hampers their applicability as biocatalysts for the synthesis of modified nucleosides. We now report the production and purification of a novel NDT from Archaeoglobus veneficus that is endowed with native ribosyltransferase activity and hence it is more properly classified as an N-ribosyltransferase (AvNRT). Biophysical and biochemical characterization revealed that AvNRT is a homotetramer that displays maximum activity at 80°C and pH 6 and shows remarkably high stability at high temperatures (60–80°C). In addition, the activity of AvNRT was found to increase up to 2-fold in 4 M NaCl aqueous solution and to be retained in the presence of several water-miscible organic solvents. For completeness, and as a proof of concept for possible industrial applications, this thermophilic and halotolerant biocatalyst was successfully employed in the synthesis of different purine ribonucleoside analogs.

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Gúzman Villareal, Lilian | 2020

Manuscrito ganador del primer lugar del III concurso de microcuento. Microcuento de suspenso, que cuestiona la percepción de la realidad.

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Nanometric particles of high economic value in coal fire region: Opportunities for social improvement
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Silva Oliveira, Luis Felipe | 2020-02-10

Spontaneous coal combustion in the La Guajira coals was studied for the presence of carbon nanophases (e.g., carbon nanotubes), occurrence of rare earth elements (REEs) in them, and the probable mechanisms for concentration of these rare compounds. For this purpose, various techniques such as scanning electron microscopy (SEM), Field-emission SEM, transmission electron microscopy (TEM), high-resolution TEM, and focused ion beam (FIB) were used. The development and alteration of the nanoparticles by geo-processes during the early modification periods of coal combustion were explored. Certain types of carbon nanophases and REE compounds may constitute nanominerals and ultra-fine particles accumulated in the coal peat. Assemblages of these nanophases (crystalline and amorphous compounds), predominantly the clay-monazite relationship and its connection to tonsteins in the coal combustion zones in the east region of the coal mines studied in this work, indicate that the coal area was subjected to REE concentration. The carbon nanophases contained several potential hazardous elements (PHEs), including, arsenic, bromine, cadmium, chlorine, fluorine, mercury, and other PHEs. While carbon nanotubes have been known to be produced from spontaneous combustion of coal of varying ranks, the present work is the first report on the naturally occurring REEs and carbon nanophases in the Colombian coal mining area.

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Nanomineralogy of evaporative precipitation of efflorescent compounds from coal mine drainage
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O. Silva, Luis F. | 2020

Efflorescent nanophases (NPs) are found as a transitory accumulation of potentially hazardous elements (PHEs), particularly in tropical climates. The central objective of this study was to investigate the distribution of PHEs with NPs through the evaporative formation structures (EFS) of enormously PHEs-rich coal-mine drainages (CMD). The EFS were studied in natural coal mine drainage for five months in order to determine their geochemical and ecological structures and to assess their position in the reduction of PHEs in nature. The largest coal-fired power plant in South America, located in south Brazil, is used as an example of such a problem. In this work, a novel methodology for the analysis of PHEs in CMD precipitates is proposed for this affected coal area. The analytical method, combining X-Ray Diffraction (XRD) and advanced electron microscopies, shows the importance of nanomineralogy in understanding different circumstances of coal contamination. Several ultrafine-nanoparticles (UNPs) were identified in the sampled soils and river sediments together with the PHEs. A decrease in PHEs was identified in association with UNPs. However, further investigations are required with regard to the mobility of PHEs in water, atmosphere, soils, and sediments. The EPS was thoroughly studied, acquiring suitable understanding with investigational facts for Ca and Fe-sulphates, pickeringite, and several amorphous phases.

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Nanomineralogy of mortars and ceramics from the Forum of Caesar and Nerva (Rome, Italy): The protagonist of black crusts produced on historic buildings
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Oliveira S., Marcos L | 2021

The recent focus of the impacts of atmospheric pollution on effective conservation methods for historic structures of great cultural heritage has been shown to be of critical importance for preservation. This work focuses on medieval Roman mortars and ceramics from the historic Forum of Caesar and Nerva, in Rome, Italy, and analyzes the urgency of repair of defects in rendered façades based on the inspection of surfaces where defects were detected, defining a methodology to predict the repair urgency of defects and building elements. X-ray spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and X-ray powder diffraction (XRD) analyses are well equipped to study mineralogy, ultra-fine particles, and nanoparticles (NPs, minerals and amorphous phases) that are present in medieval Roman ruins. Applied analysis of ruin-derived mortar and ceramics detected the presence of materials, primarily constituted of quartz, alumino-silicates, Fe-hydr/oxides, portions of amorphous phases, calcareous minerals, pyroxene, and carbonaceous materials. The Forum of Caesar and Nerva are two of the greatest remaining symbols of historic Roman construction. Many compounds recognized by XRD can be revealed by advanced microscopies and vice versa. The incidence of NPs containing potentially toxic elements (PTEs), and numerous carbonaceous complexes linked with building material alterations due to moisture and atmospheric contamination were also discovered. This study assesses the philosophies of preservation and culture, while considering the exhaust emitted by vehicular traffic in order to propose a justifiable and effective method to best conserve historic Roman structures located in high traffic areas.

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Nanomineralogy of mortars and ceramics from the Forum of Caesar and Nerva (Rome, Italy): the protagonist of black crusts produced on historic buildings
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Silva Oliveira, Marcos Leandro | 2021

The recent focus of the impacts of atmospheric pollution on effective conservation methods for historic structures of great cultural heritage has been shown to be of critical importance for preservation. This work focuses on medieval Roman mortars and ceramics from the historic Forum of Caesar and Nerva, in Rome, Italy, and analyzes the urgency of repair of defects in rendered façades based on the inspection of surfaces where defects were detected, defining a methodology to predict the repair urgency of defects and building elements. X-ray spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and X-ray powder diffraction (XRD) analyses are well equipped to study mineralogy, ultra-fine particles, and nanoparticles (NPs, minerals and amorphous phases) that are present in medieval Roman ruins. Applied analysis of ruin-derived mortar and ceramics detected the presence of materials, primarily constituted of quartz, alumino-silicates, Fe-hydr/oxides, portions of amorphous phases, calcareous minerals, pyroxene, and carbonaceous materials. The Forum of Caesar and Nerva are two of the greatest remaining symbols of historic Roman construction. Many compounds recognized by XRD can be revealed by advanced microscopies and vice versa. The incidence of NPs containing potentially toxic elements (PTEs), and numerous carbonaceous complexes linked with building material alterations due to moisture and atmospheric contamination were also discovered. This study assesses the philosophies of preservation and culture, while considering the exhaust emitted by vehicular traffic in order to propose a justifiable and effective method to best conserve historic Roman structures located in high traffic areas.

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Nanominerals and potentially hazardous elements from coal cleaning rejects of abandoned mines: Environmental impact and risk assessment
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Fdez Ortiz De Vallejuelo, Silvia | 2017

Soils around coal mining are important reservoir of hazardous elements (HEs), nanominerals, and ultrafine compounds. This research reports and discusses the soil concentrations of HEs (As, Cd, Cr, Cu, Ni, Pb, and Zn) in coal residues of abandoned mines. To assess differences regarding environmental impact and risk assessment between coal abandoned mines from the Santa Catarina state, eighteen coal cleaning rejects with different mineralogical and chemical composition, from eight abandoned mines were collected. Nanominerals and ultra-fine minerals from mining-contaminated areas were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscope (HR-TEM), providing new information on the mineralogy and nano-mineralogy of these coal residues. The total contents of 57 elements (HEs, alkali metals, and rare earth elements) were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The calculation of NWACs (Normalized Average Weighted Concentration), together with the chemometric analysis by Principal component analysis (PCA) confirmed the variability of the samples regarding their city and their mine of origin. Moreover, the results confirmed the existence of hotspots in mines near urban areas.

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Nanominerals and potentially hazardous elements from coal cleaning rejects of abandoned mines: Environmental impact and risk assessment
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Fdez Ortiz De Vallejuelo, Silvia | 2017

Soils around coal mining are important reservoir of hazardous elements (HEs), nanominerals, and ultrafine compounds. This research reports and discusses the soil concentrations of HEs (As, Cd, Cr, Cu, Ni, Pb, and Zn) in coal residues of abandoned mines. To assess differences regarding environmental impact and risk assessment between coal abandoned mines from the Santa Catarina state, eighteen coal cleaning rejects with different mineralogical and chemical composition, from eight abandoned mines were collected. Nanominerals and ultra-fine minerals from mining-contaminated areas were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscope (HR-TEM), providing new information on the mineralogy and nano-mineralogy of these coal residues. The total contents of 57 elements (HEs, alkali metals, and rare earth elements) were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The calculation of NWACs (Normalized Average Weighted Concentration), together with the chemometric analysis by Principal component analysis (PCA) confirmed the variability of the samples regarding their city and their mine of origin. Moreover, the results confirmed the existence of hotspots in mines near urban areas.

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Nanominerals assemblages and hazardous elements assessment in phosphogypsum from an abandoned phosphate fertilizer industry
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Frantz Lütke, Sabrina | 2020

The present work investigates hazardous elements and nanomineralogical assemblages of phosphogypsum waste from an abandoned phosphate fertilizer industry located in Santa Catarina state (Brazil). Correlations between the chemical composition, nanominerals, and ultrafine particles are discussed. Multifaceted physical-geochemical study provided a careful understanding of the nanomineralogical assemblage of the phosphogypsum waste. The electron beam investigation revealed the presence of many hazardous elements in the ultrafine particles. Cr, Pb, Mn, Se, Sr, and Zr, among others, were found in individual ultrafine particles and nanominerals in all studied samples. Besides that, rare earth elements were found in different concentration ranges, being Ce, La, and Nd, the rare earth elements, found in the higher concentrations, above 900 mg kg−1. The data supplied by this article are important to characterize the phosphogypsum waste, assessing the potential hazard to the environment and human health, and also, provides information to enable the designing of alternatives to manage this waste.

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Nanoparticles and interfaces with toxic elements in fluvial suspended sediment
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Silva Oliveira, Luis Felipe | 2021

Studies examining nanoparticles (NPs) and hazardous elements (HEs) contained in suspended sediments (SSs) are vital for watershed administration and ecological impact evaluation. The biochemical consequence of titanium-nanoparticles (Ti-NPs) from SSs in Colombia's Magdalena River was examined utilizing an innovative approach involving nanogeochemistry in this study. In general, the toxicity and the human health risk assessment associated with the presence of some Ti-NPs + HEs in SSs from riverine systems need to be determined with a robust analytical procedure. The mode of occurrence of Ti-NPs, total Ti and other elements contained within SSs of the Magdalena River were evaluated through advanced electron microscopy (field emission scanning electron microscope-FE-SEM and high resolution transmission electron microscope-HR-TEM) coupled with an energy dispersive X-ray microanalysis system (EDS); X-Ray Diffractions (XRD); and inductively coupled plasma-mass pectrometry (ICP-MS). This work showed that enormous quantities of Ti-NPs were present in the river studied and that they displayed diverse eochemical properties and posed various possible ecological dangers. Ti-NP contamination indices must be established for measuring the environmental magnitudes of NP contamination and determining contamination rank among rivers. Finally, SS contamination guidelines must be recommended on an international level. This study contributes to the scientific understanding of the relationship of HE and Ti-NP dynamics from SSs in riverine systems around the world.

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Nanoparticles as vectors of other contaminants in estuarine suspended sediments: natural and real conditions
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Silva Oliveira, Marcos Leandro | 2021

Studding the behaviour and danger of nanoparticles (NPs, minerals and amorphous phases) in the estuarine ecosystem is presently incomplete by the lack of measureable description of NPs in the ecological conditions, such as suspended-sediments (SS). In the last years, several works have revealed the toxic consequences of ultra-fine and nanoparticulate compounds on diverse systems, raising apprehensions over the nanocontaminants behaviour and destiny in the numerous ecological partitions. The general objective of the manuscript is to explain the geochemical conditions of the LES (Laguna estuarine system, southern Brazil) suspended sediments covering an area around the main South American coal plant, enhancing the creation of future public policies for environmental recovery projects. Subsequently the discharge of nanoparticles and toxic element (TE) in the ecosystem, NPs react with several constituents of the nature and suffers active alteration progressions. Contamination coming from engineering actions, wastewater, are something identifiable, however when these contaminations are accompanied by other contamination sources (e.g. mining and farming) the work gets defaulted. By combining material about the concentration of TE contaminants and NPs occurrences, this work offers novel visions into contaminant contact and the possible effects of such exposure on estuarine systems in Brazil. The results presented here will be useful for different areas of estuaries around the world.

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Nanoparticles from construction wastes: A problem to health and the environment
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L.S. Oliveira, Marcos | 2019-02-08

The present study deals with the nano-mineralogy and geochemistry of ultrafine particles in construction waste from the Porto Alegre region in Southern Brazil. Uncontrolled construction waste dumps and poor management practices in formal disposal sites in the area may increase exposure risks to population. Whilst the physicochemical properties of construction wastes are well documented in the literature, the characteristics of nanoparticles in their formulations are not well known. Given that degradation of construction materials may unlock and enable further release of nano-particulates present, we focused on the <63 mm fraction to examine the geochemistry of inhalable nano-particulates that could cause adverse health impacts on local communities. A particular feature across the studied wastes are the numerous aerodynamically favourable, spherical-shaped nanoparticles of magnetite, rutile and anatase. The detected nanoparticles contained a number of elements including Al, As, Au, Ca, Cd, Co, Cr, Cu, Hg, Na, Fe, K, S, Sn, Si and. An enrichment in metals and metalloids such as As, Co, Cr, Cu, Hg, Fe, Sn or Ta in particles in the nano-scale range in relation to larger particles was observed. The presence of carbon nanotubes was also noted. The leaching tests showed that the construction wastes did not reach the limits for their disposal as hazardous waste according the European Directive. Whilst the majority of trace elements were highly immobile, the water extractability for oxyanionic-forming metalloids suggests possible migration to surface and groundwater bodies. This work seeks to bring awareness on the impacts of unsustainable construction waste management, and the relevance of improved regulations regarding their final disposal.

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Nanoparticles from evaporite materials in Colombian coal mine drainages
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Silva Oliveira, Luis Felipe | 2020

Ultrathin and nanometric materials (minerals and amorphous phases) are detected in transitory deposits of potential hazardous elements (PHEs), especially in acidic coal mine drainages. The main goal of this work was to evaluate the occurrence of PHEs in nanoparticles (NPs) in evaporative structures in coal mining areas with high concentrations of PHEs. The precipitates were sampled in several coal mining areas in Colombia, with the purpose of evaluating the geochemical and environmental structures. In the present work, to better diagnose areas affected by coal mining, an innovative analytical procedure is proposed to define the association between PHEs in mine drainage sediments. The procedure includes the analytical study with X-Ray Diffraction (XRD) and advanced electron microscopy, before and after a series of sequential extractions to separate amorphous, magnetic, and crystalline compounds. Of the three main types of precipitates identified, the yellowish precipitates had the highest amounts of PHEs while the white precipitates had only small amounts of PHEs and the greenish precipitates contained TiO2 nanoparticles. The results from this study will be usable for more than fifty countries that have coal mine drainages.

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Nanoparticles generated during volcanic rock exploitation: an overview
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Gindri Ramos, Claudete | 2021

Nanoparticles (NPs) from the mining of volcanic rocks have been a matter of concern around the world because they can pose environmental and human health risks. The nanoparticles are pointed as opportunities of application in a large field of knowledge. The aim of this study is to provide an overview of scientific publications on the success rates of mineral nanoparticles, the use of soil remineralizers as an alternative for replacing highly soluble fertilizers and their potential risk to human health and the environment. Nanoparticles were successful used as a filter agent and may act as carrier agent of metals and molecules through the environment compartments; rock powder was used as a litho-fertilizer in nature or enriched with nutrients and pesticides for plant disease control. However, nanoparticles were also identified as particle promoting of human diseases. Finally, this work addresses nanoparticles derived from volcanic rock mining and highlights the relevance of developing cleaner procedures to minimize exposure to these materials and is therefore of direct relevance to both the volcanic rock mining and agriculture sector and health.

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Nanoparticles in fossil and mineral fuel sectors and their impact on environment and human health: A review and perspective
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Silva Oliveira, Luis Felipe | 2021

Nanoscience and technology have enabled better insights into the environmental and health impacts arising from the mining, production and use of fossil and mineral fuels. Here we provide an overview of the nanoscience-based applications and discoveries concerning coal and mineral fuel (i.e., uranium-containing minerals) mining, refining/production, use, and disposal of wastes. These processes result in massive nanoparticle release and secondary nanoparticle generation which have highly significant environmental implications and human health consequences on local, regional, and even global levels. Until recently, very little was known about nanoparticle fractions. Recent advancements and sophistications enable us to detect, collect and study these materials which are roughly 1 nm (0.001 μm) up to several tens of nanometers in size. These materials are known to behave differently (chemically, electrically, and mechanically), relative to their macroscopic equivalents. This is what makes nanoscience fascinating and difficult to predict, underscoring the importance of this emerging new field. For example, nanoparticles associated with coal and mineral fuel influence the release, uptake, and transportation of hazardous elements associated with mining, processing, and waste storage in the surrounding areas. This includes long distance transport down streams, rivers, and eventually to oceans such as from coal and uranium mine drainages. In terms of human health, in all phases of mining, production/refining, use, and waste disposal, the associated nanoparticles can be acquired through oral ingestion, inhalation, and dermal absorption. Inhalation has been shown to be particularly damaging, where lung, heart, kidney, and brain diseases are prevalent. Relative to all other fields of science and engineering associated with coal and mineral fuel mining, production, use, and clean-up efforts, nanoscience, although a much newer field then the rest by comparison, is still greatly under-represented and under-utilized. There is also a continuing gap between what we so far know about the behavior of nanoparticles, and what remains to be discovered.

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La narración como mediación didáctica en la comprensión lectora de estudiantes de tercer grado de básica primaria
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Meléndez Mendoza, Mauricio | 2021

The research objective was to determine the effect of narration as a didactic mediation in reading comprehension in third grade students of elementary school, basing in a positivist paradigm. The type of research was experimental with an explanatory level, under a quasi-experimental design, with two groups (control and experimental), and two measurements, pre-test and post-test with a population of sixty (60) children of the third grade of primary basic education. ; of the Macondo Departmental Ethnoeducational Institution, it was used a 25-item reading comprehension questionnaire with 4 alternative responses, it was validated by three (3) experts and had an Alpha Cronbach reliability of 0.81, the statistical data were processed with measures of central tendency, measures of dispersion, and inferential statistics. The results show in the Pre-test a low average level of reading comprehension, which improved after the application of the program to a medium level, due to the above, it was concluded that the narration strategy as didactic mediation had favorable effects In reading comprehension, it was recommended to apply the intervention to another population with similar characteristics and to motivate teachers, through an intervention plan to develop their own skills related to expression, feelings, interpretation and comprehension of texts .

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Natural ester fluids applications in transformers as a sustainable dielectric and coolant
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Hernández Herrera, Hernan | 2019

New requirements for a better sustainable energy policy around the world is easy to observe, many projects in sustainable energy are developed wherein the academia works together the authorities and commercial firms such as electrical grid utilities. In distribution transformers one of the suggested solutions is to replace mineral oils used as dielectric and coolant for natural ester fluids, they provide improved technical properties making them a safe substitute of mineral oil. Natural esters are based on clean technology in order to guarantee requirements from utilities. The main goal of the present paper is to present a technical-economic analysis obtained from five years of applications of oil-immersed transformers using natural ester fluids in Colombia. The methodology considers forty-four oil-immersed distribution Transformers, a half use mineral oil and the other side use natural ester, operating under the same load regime. Results evidenced the feasibility of implementing this technology because the costs are very similar and the reduction of risks and environmental impact is considerable. © 2019 Author(s).

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Natural language explanation model for decision trees
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Silva, Jesús | 2020-02-01

This study describes a model of explanations in natural language for classification decision trees. The explanations include global aspects of the classifier and local aspects of the classification of a particular instance. The proposal is implemented in the ExpliClas open source Web service [1], which in its current version operates on trees built with Weka and data sets with numerical attributes. The feasibility of the proposal is illustrated with two example cases, where the detailed explanation of the respective classification trees is shown.

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Naturally growing grimmiaceae family mosses as passive biomonitors of heavy metals pollution in urban-industrial atmospheres from the Bilbao Metropolitan area
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Gallego-Cartagena, Euler | 2021

In analytical chemistry, biomonitoring is known as the methodology, which consider the use of living organisms to monitor and assess the impact of different contaminants in a known area. This type of monitoring is a relatively inexpensive method and easy to implement, being a viable alternative to be developed in sites where there is no infrastructure/instruments for a convenctional air quality monitoring. These organisms, having the capability to monitor the pollution, are also known as passive biomonitors (PBs), since they are able to identify possible contamination sources without the need of any additional tool. In this work, a multianalytical methodology was applied to verify the usefulness of naturally growing Grimmia genus mosses as PBs of atmospheric heavy metals pollution. Once mosses were identified according to their morphology and taxonomy, thei ability to accumulate particulate matter (PM) was determined by SEM. EDS coupled to SEM also allowed to identify the main metallic particles deposited and finally, an acid digestion of the mosses and a subsequent ICP-MS study define more precisely the levels of metals accumulated on each collected moss. The study was focused on six sampling locations from the Bilbao Metropolitan area (Biscay, Basque Country, north of Spain). The experimental evidences obtained allowed to propose naturally growing Grimmia genus as PB of atmospheric heavy metals pollution and to identify the anthropogenic sources that contribute to the emission of the airborne particulate matter rich in metals, evaluating in this sense the atmospheric heavy metals pollution of the selected locations.

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Near ω-continuous multifunctions on bitopological spaces
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Rosas, E. | 2019-10

In this paper, we introduce and study basic characterizations, several properties of upper (lower) nearly (i; j)-!-continuous multifunctions on bitopological space.

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