Now showing items 1577-1587 of 1587

Water treatment using porous ceramics based on recycled diatomite and kaolin

MOGOLLON CUELLAR, ZULMA YARLEY; Silva Rivero, Yobana Iris Ney; Peña Rodriguez, Gabriel (Contemporary Engineering SciencesSofia , Bulgaria, 2018-09-06)

The treatment of waters using filtering process through sintered porous ceramics based on diatomite and kaolin is reported. The water samples were prepared in low = 50%, medium = 100% and high = 150% concentrations, ...
Waterborne hyperbranched alkyd-acrylic resin obtained by miniemulsion polymerization

Lopez, Betty; Murillo, Edwin A. (PolimerosBrasilia , Brasil, 2016-12-08)

Four waterborne hyperbranched alkyd-acrylic resins (HBRAA) were synthesized by miniemulsion polymerization from a hyperbranched alkyd resin (HBR), methyl methacrylate (MMA), butyl acrylate (BA) and acrylic acid (AA), by ...
Waterborne star-shaped styrene-alkyd resins

Murillo, Edwin A. (Journal of Applied Polymer Science, 2019-08-13)

Waterborne star-shaped styrene-alkyd resins (SSARs) were synthesized from a branched alkyd resin (AR) and styrene (St) by miniemulsion polymerization. SSARs are an environmentally friendly material. The ratio of AR to St ...
WaterrelationsandgasexchangeinRuilopezia atropurpurea(Asteraceae),agiantrosettegrowingundercontrastingmicroclimatesinthehightropicalAndes

Rada, Fermin; NAVARRO DURAN, ANTONIO (CaldasiaBogotá, Colombia, 2022-10-10)

Tropical high andean ecosystems, known as paramos, are unique because they are highly diverse, have a high number of endemic species, and play an essential role in different ecosystem services, but are especially susceptible ...
Wear and corrosion behaviour of Al2O3-TiO2 coatings produced by flame thermal projection

Hector Jaime, Dulce-Moreno; Ferrer, Martha; Vargas, Fabio (Journal of Physics: Conference SeriesBogota , Colombia, 2017-12-29)

Evaluated the wear resistance and the coatings corrosion behaviour of Al2O3-TiO2 prepared by thermal spraying by flame on AISI 1020 carbon steel substrates, previously coated with an alloy base Ni. For this purpose, were ...
Wear synergy of copper-iron mixtures processed by powder metallurgy

Operador, W; Bautista-Ruiz, Jorge; Caicedo, J (Rasayan Journal of ChemistryIndia, 2021)

Through the powder metallurgy process, copper and iron powders were mixed in the proportions Cu between 15% to 75% and iron from 25% to 85% that made up the binary material systems. The X-ray diffraction technique was ...
Web 2.0 Tools: A mediation in the teaching and learning process of mathematics and physics in higher education

Prada Nuñez, Raul; Paz Montes, Luisa Stella; HERNANDEZ SUAREZ, CESAR AUGUSTO (Revista EspaciosVenezuela, 2020-12-30)

The objective was to design a didactic experience that would facilitate the processes of teaching and learning of functions in the students of a public university. A quantitative approach is adopted at the descriptive ...
Web services selection a perspective of computational physics

Adarme Jaimes, Marco Antonio; Jimeno, Miguel; Puerto, E G (Journal of Physics: Conference SeriesInglaterra, 2020-08-05)

Concerning computational physics, web services are conceived as mathematical units that are experienced in different systems that offer service composition. Due to the exponential growth of web services and their deployment ...
With the Newsroom at Home: Routines and Tensions of Women Journalists in Times of Covid-19

Espinel Rubio, Gladys Adriana; Prada Nuñez, Raul; Muñoz Balcázar, Kelly Giovanna; HERNANDEZ SUAREZ, CESAR AUGUSTO (Comunicação e SociedadePortugal, 2021-12)

This article identifies the routines and working practices of women journalists from Colombia and Venezuela in the framework of the health emergency caused by covid-19 in the countries where they work. It is a quantitative ...
Zika en la gestación. Afectación de las destrezas de ejecución y edad madurativa en infantes

Hernandez Vergel, Viviana Karina; Prada Nuñez, Raul; HERNANDEZ SUAREZ, CESAR AUGUSTO (Revista CuidarteBucaramanga,Colombia, 2022-05-24)

El virus Zika se transmite por la picadura de mosquitos infectados, pero también puede ocurrir a través de una infección intrauterina antes del parto, y el virus pasa al feto. Objetivo: describir ...
La zona de posibilidades en el proceso de aprendiencia del residente digital: un análisis cualitativo en la red de experiencias matemáticas de Norte de Santander

Gómez Valderrama, Carlos; Prada Nuñez, Raul; HERNANDEZ SUAREZ, CESAR AUGUSTO (Educación y HumanismoColombia, 2020-03-03)

Objetivo: Identificar, determinar y describir la zona de posibilidades en el estar-enproceso-de-aprender del residente digital, según mapeo visitante/residente, para mejorar la práctica de construcción de la Red Personal ...

Envíos recientes

Water treatment using porous ceramics based on recycled diatomite and kaolin
...
MOGOLLON CUELLAR, ZULMA YARLEY | 2018-09-06

The treatment of waters using filtering process through sintered porous ceramics based on diatomite and kaolin is reported. The water samples were prepared in low = 50%, medium = 100% and high = 150% concentrations, taking as reference point the maximum value allowed according to the resolution 2115 - 2007. The treated parameters were alkalinity; hardness to calcium, magnesium and total; chlorides; sulfates and total iron. The porous ceramics were formed by slip casting in plaster mold, from pastes with weight percentage of 50% recycled diatomite from the beer industry, 40% kaolin and 10% calcium carbonate. The particle sizes of the ceramic powders were the passed through ASTM 200 sieve. The drying of the ceramics was carried out at room temperature for 24 h, then by forced circulation oven Memmert UF-110 at 100 ° C for an equal time. The sintering of the ceramics was carried out in Vulcan D-130 electric muffle, at a maximum temperature of 1000 ° C for two hours, with a heating ramp of 10 ° C/min. The morphology of the ceramics was studied using scanning electron microscopy (SEM), while the physic ceramic analyses was evaluated according to ISO 10545-3 standard. Our results, reported what porous ceramics efficiency for the removal of chlorides up to 50%, while elimination of sulfates was approximately 43%, on the other hand, the total iron was removed up to 95%, likewise,it was evidenced that ceramics are not efficient in the treatment of hardness and alkalinity of waters with high concentrations

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Waterborne hyperbranched alkyd-acrylic resin obtained by miniemulsion polymerization
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Lopez, Betty | 2016-12-08

Four waterborne hyperbranched alkyd-acrylic resins (HBRAA) were synthesized by miniemulsion polymerization from a hyperbranched alkyd resin (HBR), methyl methacrylate (MMA), butyl acrylate (BA) and acrylic acid (AA), by using benzoyl peroxide (BPO) and ammonium persulfate (AP) as initiators. The reaction between HBR and acrylic monomers was evidenced by differential scanning calorimetric (DSC), nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The conversion percentage, glass transition temperature (Tg), content of acrylic polymer (determined by soxhlet extraction) and molecular weight increased with the content of acrylic monomers used in the synthesis. The main structure formed during the synthesis was the HBRAA. The analysis by dynamic light scattering (DLS) showed that the particle size distribution of HBRAA2, HBRAA3 and HBRAA4 resins were mainly monomodal. The film properties (gloss, flexibility, adhesion and drying time) of the HBRAA were good.

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Waterborne star-shaped styrene-alkyd resins
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Murillo, Edwin A. | 2019-08-13

Waterborne star-shaped styrene-alkyd resins (SSARs) were synthesized from a branched alkyd resin (AR) and styrene (St) by miniemulsion polymerization. SSARs are an environmentally friendly material. The ratio of AR to St for obtaining SSARs was as follows: 50:50 (SSAR1), 60:40 (SSAR2), 70:30 (SSAR3), and 80:20 (SSAR4). The conversion percentage was directly proportional to St used, and was higher than 94.0 %. Infrared analysis and protonic nuclear magnetic resonance revealed the reaction between AR and St. The synthesis process also leads to the formation of polystyrene and its concentration increases with the concentration of St. The values of the reacted double-bond fractions were higher than 17.80%. The SSARs drop size was bigger than the particle size. The miniemulsion colloidal stability was good at room temperature. The SSARs zeta potential was between −55 and −90 mV. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48386.

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WaterrelationsandgasexchangeinRuilopezia atropurpurea(Asteraceae),agiantrosettegrowingundercontrastingmicroclimatesinthehightropicalAndes
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Rada, Fermin | 2022-10-10

Tropical high andean ecosystems, known as paramos, are unique because they are highly diverse, have a high number of endemic species, and play an essential role in different ecosystem services, but are especially susceptible to climate change. Most of the giant rosettes, a dominant growth-form in the paramos, depend on unique features like stems protected by marcescent leaves, voluminous stem pith, and leaf pubescence. However, Ruilopezia atropurpurea lacks these characteristics and must respond differently to endure the paramo extreme conditions. Additionally, unlike other rosettes, this species is found under contrasting exposed and understory microenvironments so that intraspecific plasticity is also expected. We evaluated the responses of R. atropurpurea in terms of leaf water relations, gas exchange, and morphological characteristics in temporal (seasonal and daily variations) and spatial (microsite differences) scales in a Venezuelan paramo. R. atropurpurea displayed lower leaf water potentials (minimum leaf water potentials of -1.5 MPa and -1.8 MPa at the turgor loss point), higher leaf conductance (620 mmol m-2s-1), transpiration (5 molm-2s-1), and CO2 assimilation (13 mmol m-2s-1) rates compared to other paramo giant rosettes. A reduction in leaf area and specific leaf area occurred from understory to exposed sites. R. atropurpurea diverges from the typical responses of most paramo giant rosettes to the extreme environmental conditions. This species’ morphological and physiological plasticity permits it inhabit under variable microclimatic conditions, but despite its confirmed plasticity, it is not able to reach higher elevations as other giant rosettes successfully have.

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Wear and corrosion behaviour of Al2O3-TiO2 coatings produced by flame thermal projection
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Hector Jaime, Dulce-Moreno | 2017-12-29

Evaluated the wear resistance and the coatings corrosion behaviour of Al2O3-TiO2 prepared by thermal spraying by flame on AISI 1020 carbon steel substrates, previously coated with an alloy base Ni. For this purpose, were controlled parameters of thermal spraying and the use of powders of similar but different chemical composition is taken as a variable commercial reference for ceramic coating. SEM images allowed to know the morphology of the powders and coatings. Electrochemical techniques (Tafel) were applied to evaluate the protection against corrosion. Coatings were tested for wear with a tribometer configuration bola-disco. It was determined that the phases present in coatings are directly relate to the behaviour against corrosion and wear them. Keywords: wear, corrosion, thermal imaging.

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Wear synergy of copper-iron mixtures processed by powder metallurgy
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Operador, W | 2021

Through the powder metallurgy process, copper and iron powders were mixed in the proportions Cu between 15% to 75% and iron from 25% to 85% that made up the binary material systems. The X-ray diffraction technique was used to determine the crystalline structure. Material systems were topographically characterized with optical microscopy. Tribology tests were established using a pin on the disk tribometer. It was determined that the stability of the mixture has different behaviors depending on the evaluated system because the wear system caused, indicating that the phenomenon can be additive. The mixed material is characterized by high friction coefficient and high wear due to the samples' specific properties by increasing the amount of iron in the mixture. The systems analyzed indicate that mechanical degradation was mainly reduced. Dimensional variation of the study specimens was evidenced due to the influence of copper in the system. Only the austenitic structure of the steel was observed, which indicates a complete diffusion of the copper.

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Web 2.0 Tools: A mediation in the teaching and learning process of mathematics and physics in higher education
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Prada Nuñez, Raul | 2020-12-30

The objective was to design a didactic experience that would facilitate the processes of teaching and learning of functions in the students of a public university. A quantitative approach is adopted at the descriptive level. The questionnaire is used as an instrument. As a result, it was found that the activities implemented facilitated the learning of mathematics applied to physics. The contributions are concluded as positive since the students were able to focus on specific aspects of the selected lessons applying physical reasoning by means of the Web 2.0 resource.

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Web services selection a perspective of computational physics
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Adarme Jaimes, Marco Antonio | 2020-08-05

Concerning computational physics, web services are conceived as mathematical units that are experienced in different systems that offer service composition. Due to the exponential growth of web services and their deployment on cloud platforms, quality of service parameters have now become an essential factor when searching for and selecting services that must satisfy specific non-functional requirements of a user application. A variety of service components are highly configurable and are dynamic scenarios because a significant number of services can meet these requirements. This work analyzes the systemic perspective of approaches for the selecting and searching of web services that have specifications of optimization strategies based on the configurable quality of service parameters with test scenarios in cloud environments that have a considerable number of services as input. The study shows that policies based on artificial intelligence and related areas are the ones with the most significant convergence, and the approaches analyzed to give a perspective of future work aimed at strategies based on automatic learning.

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With the Newsroom at Home: Routines and Tensions of Women Journalists in Times of Covid-19
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Espinel Rubio, Gladys Adriana | 2021-12

This article identifies the routines and working practices of women journalists from Colombia and Venezuela in the framework of the health emergency caused by covid-19 in the countries where they work. It is a quantitative research at a descriptive cross-sectional level in which an instrument made up of 26 questions organized into five categories of analysis was used. Categories include family–work relationship, working life, and health and well-being, and the questionnaire was applied to 110 professionals from Colombia and Venezuela. It was found that the compulsory confinement hastened the insertion of journalists in the use of information and communication technologies, applications, and software for content production. Although they were already working in digital media, they had to develop new skills in this field. For 47% of them, their working hours were extended for more than 3 hours a day, which for 79% represents family tensions, given that 38% have underage children or older adults under their care. However, during the confinement, their participation in the formation of public opinion was also expanded through their personal social networks, incorporating corruption issues and citizen complaints. Regarding their routines, it is concluded that the pandemic transformed access to information sources, newsrooms, and, therefore, the dynamics of news production, so we are faced with a new way of doing journalism that puts reporting and ethics into tension with information and communication technologies.

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Zika en la gestación. Afectación de las destrezas de ejecución y edad madurativa en infantes
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Hernandez Vergel, Viviana Karina | 2022-05-24

El virus Zika se transmite por la picadura de mosquitos infectados, pero también puede ocurrir a través de una infección intrauterina antes del parto, y el virus pasa al feto. Objetivo: describir el nivel de afectación en destrezas de ejecución y edad madurativa de niños del programa Valientes del Futuro con la infección neonatal por virus Zika. Materiales y Métodos: La investigación se enmarca con enfoque cuantitativo de tipo correlacional apoyada con una investigación de campo y diseño no experimental, con una muestra de 15 infantes de 3, 4 y 5 años. La técnica de recolección utilizada fue la Escala Abreviada. Resultados: En cuanto a las áreas evaluadas con respecto a la edad madurativa se encontró que la ponderación de la destreza motora y praxis halló un coeficiente de correlación de 0,601 (moderada) y en la muestra de las destrezas de ejecución de los niños de 3 años con zika gestacional se obtuvo una correlación de 0,853 (fuerte). Discusión: la infección por virus zika en niños y niñas, adquirida durante la gestación, limita fuertemente las destrezas de ejecución propias de la edad madurativa en esta población. Conclusiones: Existe correlación entre los infantes con zika gestacional y la afectación fuerte en las acciones o comportamientos que un paciente tenga para moverse e interactuar físicamente con actividades, objetos y por ende realizar una actividad motora aprendida.

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La zona de posibilidades en el proceso de aprendiencia del residente digital: un análisis cualitativo en la red de experiencias matemáticas de Norte de Santander
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Gómez Valderrama, Carlos | 2020-03-03

Objetivo: Identificar, determinar y describir la zona de posibilidades en el estar-enproceso-de-aprender del residente digital, según mapeo visitante/residente, para mejorar la práctica de construcción de la Red Personal de Aprendizaje. Método: Se trata de una investigación cualitativa, cuyos sujetos de investigación son profesores que integran la Red de Experiencias Matemáticas de Norte de Santander, Colombia. La información se recolectó a través de grupos de discusión en los foros temáticos. Resultados: Se muestra la zona de posibilidades en el proceso de aprendiencia del residente digital como resultado de la investigación. Discusión y Conclusiones: Se concluyó que la zona de posibilidades puede ser una zona difusa para las personas que no tienen una concepción clara de lo que representa la Red Personal de Aprendizaje, para beneficiarse de la inteligencia colectiva de este, y, por ende, precisar nuevos nodos de saberes.

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Repositorio Digital

Browsing B. Investigación by Title

Water treatment using porous ceramics based on recycled diatomite and kaolin

Waterborne hyperbranched alkyd-acrylic resin obtained by miniemulsion polymerization

Waterborne star-shaped styrene-alkyd resins

WaterrelationsandgasexchangeinRuilopezia atropurpurea(Asteraceae),agiantrosettegrowingundercontrastingmicroclimatesinthehightropicalAndes

Wear and corrosion behaviour of Al2O3-TiO2 coatings produced by flame thermal projection

Wear synergy of copper-iron mixtures processed by powder metallurgy

Web 2.0 Tools: A mediation in the teaching and learning process of mathematics and physics in higher education

Web services selection a perspective of computational physics

With the Newsroom at Home: Routines and Tensions of Women Journalists in Times of Covid-19

Zika en la gestación. Afectación de las destrezas de ejecución y edad madurativa en infantes

La zona de posibilidades en el proceso de aprendiencia del residente digital: un análisis cualitativo en la red de experiencias matemáticas de Norte de Santander

Envíos recientes

Water treatment using porous ceramics based on recycled diatomite and kaolin

Waterborne hyperbranched alkyd-acrylic resin obtained by miniemulsion polymerization

Waterborne star-shaped styrene-alkyd resins

WaterrelationsandgasexchangeinRuilopezia atropurpurea(Asteraceae),agiantrosettegrowingundercontrastingmicroclimatesinthehightropicalAndes

Wear and corrosion behaviour of Al2O3-TiO2 coatings produced by flame thermal projection

Wear synergy of copper-iron mixtures processed by powder metallurgy

Web 2.0 Tools: A mediation in the teaching and learning process of mathematics and physics in higher education

Web services selection a perspective of computational physics

With the Newsroom at Home: Routines and Tensions of Women Journalists in Times of Covid-19

Zika en la gestación. Afectación de las destrezas de ejecución y edad madurativa en infantes

La zona de posibilidades en el proceso de aprendiencia del residente digital: un análisis cualitativo en la red de experiencias matemáticas de Norte de Santander

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Browsing B. Investigación by Title

Water treatment using porous ceramics based on recycled diatomite and kaolin ﻿

Waterborne hyperbranched alkyd-acrylic resin obtained by miniemulsion polymerization ﻿

Waterborne star-shaped styrene-alkyd resins ﻿

WaterrelationsandgasexchangeinRuilopezia atropurpurea(Asteraceae),agiantrosettegrowingundercontrastingmicroclimatesinthehightropicalAndes ﻿

Wear and corrosion behaviour of Al2O3-TiO2 coatings produced by flame thermal projection ﻿

Wear synergy of copper-iron mixtures processed by powder metallurgy ﻿

Web 2.0 Tools: A mediation in the teaching and learning process of mathematics and physics in higher education ﻿

Web services selection a perspective of computational physics ﻿

With the Newsroom at Home: Routines and Tensions of Women Journalists in Times of Covid-19 ﻿

Zika en la gestación. Afectación de las destrezas de ejecución y edad madurativa en infantes ﻿

La zona de posibilidades en el proceso de aprendiencia del residente digital: un análisis cualitativo en la red de experiencias matemáticas de Norte de Santander ﻿

Envíos recientes

Water treatment using porous ceramics based on recycled diatomite and kaolin

Waterborne hyperbranched alkyd-acrylic resin obtained by miniemulsion polymerization

Waterborne star-shaped styrene-alkyd resins

WaterrelationsandgasexchangeinRuilopezia atropurpurea(Asteraceae),agiantrosettegrowingundercontrastingmicroclimatesinthehightropicalAndes

Wear and corrosion behaviour of Al2O3-TiO2 coatings produced by flame thermal projection

Wear synergy of copper-iron mixtures processed by powder metallurgy

Web 2.0 Tools: A mediation in the teaching and learning process of mathematics and physics in higher education

Web services selection a perspective of computational physics

With the Newsroom at Home: Routines and Tensions of Women Journalists in Times of Covid-19

Zika en la gestación. Afectación de las destrezas de ejecución y edad madurativa en infantes

La zona de posibilidades en el proceso de aprendiencia del residente digital: un análisis cualitativo en la red de experiencias matemáticas de Norte de Santander

Portales Institucionales

Water treatment using porous ceramics based on recycled diatomite and kaolin

Waterborne hyperbranched alkyd-acrylic resin obtained by miniemulsion polymerization

Waterborne star-shaped styrene-alkyd resins

WaterrelationsandgasexchangeinRuilopezia atropurpurea(Asteraceae),agiantrosettegrowingundercontrastingmicroclimatesinthehightropicalAndes

Wear and corrosion behaviour of Al2O3-TiO2 coatings produced by flame thermal projection

Wear synergy of copper-iron mixtures processed by powder metallurgy

Web 2.0 Tools: A mediation in the teaching and learning process of mathematics and physics in higher education

Web services selection a perspective of computational physics

With the Newsroom at Home: Routines and Tensions of Women Journalists in Times of Covid-19

Zika en la gestación. Afectación de las destrezas de ejecución y edad madurativa en infantes

La zona de posibilidades en el proceso de aprendiencia del residente digital: un análisis cualitativo en la red de experiencias matemáticas de Norte de Santander