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Thickness effect on the solvent sensing parameters of carbon black-polymer composites

ENRIQUE VIGUERAS SANTIAGO SUSANA HERNANDEZ LOPEZ CLAUDIA ALEJANDRA HERNANDEZ ESCOBAR ERASTO ARMANDO ZARAGOZA CONTRERAS JOSE RURIK FARIAS MANCILLA (2014)

investigación realizada en proyecto de Red Temática

Study of the sensing parameters: sensibility, response and recuperation times to hexane vapors for layers of different thickness of poly(butadiene) + carbon black (CB) composites is presented. The results show that sensibility increases as the CB- weight percent diminishes, being in agreement with reported results by several researches. In this work another variable was studied on the sensing parameters, the thickness. The initial electrical resistance of the studied layers increases until three magnitude orders as diminish theirs thickness and the sensibility in this study increases until one magnitude order as the layer thickness diminishes around 0.25 μm.

Programa de Mejoramiento al Profesorado (PROMEP, México), proyecto de red PROMEP 2013-2014.

Article

polymer composites sensing thicknes carbon black BIOLOGÍA Y QUÍMICA

Sensing parameters as a function of the chemical structure and thickness of two poly(styrene)-type based composites with carbon black

ETHNICE DEHONOR MARQUEZ ENRIQUE VIGUERAS SANTIAGO ALEJANDRO RAMIREZ JIMENEZ SUSANA HERNANDEZ LOPEZ (2018)

Sensing parameters of polymer composite layers were studied as a function of the polymer matrix structure and the initial resistance of the composite layers. Composites of Poly(styrene) and 4-Chloro-poly(styrene) at the same volume fraction of carbon black (8.7% V/V) were prepared by ultrasonic dispersion. Composite layers with different thicknesses and resistances were deposited by spin coating technique on flexible substrates from commercial cellulose acetate foils. Both kind of composite layers with initial resistances of 10, 50 and 100 kΩ were exposed to Acetone, Tetrahydrofuran, Chloroform and Toluene. Results evidenced that selectivity is very dependent on the chemical structure of the polymer matrix and sensitivity to the initial film electrical resistance. PS-based composite series were selective to Tetrahydrofuran whereas that 4ClPS-based composite series were selective to Acetone as expected due to their solubility parameters. For both composite series sensitivity increased for layers with less than 100 kΩ resistances. For all tested solvents 4ClPS-based composites showed higher sensitivities than PS-based composites. The response times for both series were into the range of 2 to 150 s and recovery times were in the range of 30 to 2000 s.

SIEA-UAEM, 1025/2014RIFC

Article

polysterene composites sensing carbon black BIOLOGÍA Y QUÍMICA

Estudio del Carbono Negro (Black Carbon) contenido en partículas suspendidas en ambientes urbanos

CARLOS GUADALUPE DIAZ HERNANDEZ (2016)

En las últimas décadas se ha incrementado la evidencia de que la Tierra está experimentando un cambio en la temperatura global promedio. El calentamiento global se debe a la radiación electromagnética que calienta la superficie de la Tierra y a la radiación térmica de la Tierra, estas dos corrientes de radiación deberían balancearse, pero solo una parte de esta radiación térmica sale hacia el espacio y otra parte es absorbida por ciertos gases que están presentes en la atmósfera, los gases de efecto invernadero. Los aerosoles también contribuyen al calentamiento global, ya que contienen material carbonoso en la de fracción PM2.5. Los aerosoles carbonosos se dividen en carbono elemental (EC) y carbono orgánico (OC). El EC se asocia con los términos de “Hollín” y “Black Carbón” (BC). El BC es el componente más fuerte, absorbiendo luz dentro del material particulado (PM) en los aerosoles, dispersando la luz solar entrante fuera de la superficie de la tierra, afectando la temperatura, calentando la atmósfera y cambiando el balance radiativo de la tierra. La mayoría de las caracterizaciones de EC y BC implican la colección de PM en filtros, la medición del contenido de carbono en el filtro o la atenuación de la luz reflejada. Comúnmente, se usan dos métodos termo-ópticos para medir el BC en filtros de fibra de cuarzo, el IMPROVE conocido como Reflectancia Óptica Total (TOR por sus siglas en ingles), y el método NIOSH 5040, referenciado como Transmisión Óptica Total (TOT por sus siglas en inglés). Para filtros de fibra de vidrio se usa un análisis térmico de dos pasos (Two-Step). El presente estudio representa un primer esfuerzo en conocer las concentraciones de BC en la región de Chihuahua. Por otro lado, se pretende evaluar la validez del análisis termo-gravimétrico (TGA) para análisis del BC, mediante comparación con las otras dos metodologías (TOT-TOR, Two-Step).

Master thesis

Black Carbon BIOLOGÍA Y QUÍMICA QUÍMICA OTRAS ESPECIALIDADES QUÍMICAS OTRAS OTRAS

Thickness effect on electric resistivity on polystyrene and carbon black- based composites

SUSANA HERNANDEZ LOPEZ ENRIQUE VIGUERAS SANTIAGO MIGUEL MAYORGA ROJAS DELFINO REYES CONTRERAS (2009)

Changes on electrical resistivity were experimentally studied for polystyrene and carbon black-based composites respect to the temperature. 22% w/w carbon black composite films at 30 μm, 2mm y 1cm thick were submitted to thermal heating-cooling cycles from room temperature to 100°C, slightly up to Tg of the composite. For each cycle changes on electrical resistivity constituent a hysteresis loop that depends on the sample thickness. The changes during the heating stage could be explained as a consequence of the thermal expansion and mobility of the polymer chains at Tg, producing a disconnecting of the electrical contacts among carbon black particles and an important increasing (200%) of the electrical resistivity. For each cycle, the hysteresis loop was observed in thicker samples, whereas for 30 ? m thickness sample the hysteresis loop was lost after four cycles.

CONACYT

Article

polymer composites electric resistivity carbon black CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA

Black carbon and organic carbon emissions from wildfires in Mexico

Xochitl Cruz-Nuñez MARIA DE LOURDES VILLERS RUIZ CARLOS GAY GARCIA (2014)

In Mexico, approximately 7,650 wildfires occur annually, affecting 263,115 hectares of land. In addition to their impact on land degradation, wildfires cause deforestation, damage to ecosystems and promote land use change; apart from being the source of emissions of toxic substances to the environment (i.e., hydrogen cyanide, black carbon and organic carbon).

Black carbon is a short-lived greenhouse pollutant that also promotes snow and ice melt and decreased rainfall; it has an estimated global warming potential close to 5000[1].

We present an estimate of the black carbon and organic carbon emissions from wildfires in Mexico from 2000 to 2012 using selected emission factors from the literature and activity data from local agencies. The results show average emissions of 5,955 Mg/year for black carbon and 62,085 Mg/year for organic carbon.

Black carbon emissions are estimated to be 14,888 Gg CO2 equivalent (CO2 eq) per year on average. With proper management of wildfires, such emissions can be mitigated. Moreover, improved air quality, conservation of ecosystems, improvement of visibility and maintenance of land use are a subset of the related co-benefits. Mitigating organic carbon emissions, which are ten times higher than black carbon emissions, would also prevent the morbidity and mortality impacts of toxic organics in the environment.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA black carbon organic carbon wildfires Mexico emissions

Black carbon and organic carbon emissions from wildfires in Mexico

Xochitl Cruz-Nuñez MARIA DE LOURDES VILLERS RUIZ CARLOS GAY GARCIA (2014)

In Mexico, approximately 7,650 wildfires occur annually, affecting 263,115 hectares of land. In addition to their impact on land degradation, wildfires cause deforestation, damage to ecosystems and promote land use change; apart from being the source of emissions of toxic substances to the environment (i.e., hydrogen cyanide, black carbon and organic carbon).

Black carbon is a short-lived greenhouse pollutant that also promotes snow and ice melt and decreased rainfall; it has an estimated global warming potential close to 5000[1].

We present an estimate of the black carbon and organic carbon emissions from wildfires in Mexico from 2000 to 2012 using selected emission factors from the literature and activity data from local agencies. The results show average emissions of 5,955 Mg/year for black carbon and 62,085 Mg/year for organic carbon.

Black carbon emissions are estimated to be 14,888 Gg CO2 equivalent (CO2 eq) per year on average. With proper management of wildfires, such emissions can be mitigated. Moreover, improved air quality, conservation of ecosystems, improvement of visibility and maintenance of land use are a subset of the related co-benefits. Mitigating organic carbon emissions, which are ten times higher than black carbon emissions, would also prevent the morbidity and mortality impacts of toxic organics in the environment.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA black carbon organic carbon wildfires Mexico emissions

Black carbon in PM2.5, data from two urban sites in Guadalajara, Mexico during 2008

MARIA DE LOS ANGELES TERESA LIMON SANCHEZ PATRICIA CARBAJAL ROMERO LEONEL HERNANDEZ MENA ALBERTO LOPEZ LOPEZ RICARDO COSIO RAMIREZ JOSE LUIS ARRIAGA COLINA (2011)

The BC and PM2.5 concentrations in Guadalajara, Mexico were measured in 2008 using a two–wavelength

Aethalometer!and a Partisol sampler, respectively. The aerosols were collected within two sites of the local!Network

Monitoring Stations, Centro in downtown!and Miravalle in the south. BC was measured from January to December

and PM2.5 from January to August. The 24–h PM2.5 mean concentrations were 73 and 90μg!m"3 at Centro! and

Miravalle,respectively. Mexican air quality 24–h!standard (65μg!m–3) was exceeded by 79% of the PM2.5 samples. The

BC study period was divided into three seasons: two dry seasons (DS1 and DS2) and one rainy season (RS). The hourly

BC median concentrations at Centro!and Miravalle were 1.3–8.7 and 1.5–13.8μgm"3 in DS1 while 1.4–3.3 and 1.9–6.4

μg!m–3 in RS, and 1.4–7.0μg!m"3 in DS2. When the 24–h mean BC concentration is compared to the mass

concentration on PM2.5, it shows that BC comprises less than10% of!the fine particles measured at!the same period.

Considering the meteorological parameters wind speed and wind direction, data analysis indicates that the BC

concentration is mainly influenced by local sources at Centro, but by regional and/or long–range transport and local

sources at Miravalle site. The strong correlation between BC and carbon monoxide concentrations confirmed that

these two species at the two sites have common sources.

Article

Black carbon, aerosol, PM2.5, Aethalometer, Urban atmosphere, Guadalajara, air, pollution BIOLOGÍA Y QUÍMICA

An anticorrosive magnesium/carbon nanotube composite

Hiroyuki Muramatsu MAURICIO TERRONES MALDONADO (2008)

"Here, we report a drastically improved anticorrosive characteristic of magnesium alloy composites with the introduction of multiwalled carbon nanotubes. Highly depressed corrosion of nanotube-filled magnesium composite in salt water is due to the formation of stable oxide films along the grain boundaries of magnesium. Our results indicate that carbon nanotube acted as effective multifunctional filler to improve both mechanical and anticorrosive performances of magnesium alloy."

Article

Carbon Fibers CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA FÍSICA

Cambios estacionales en la concentración de azúcares solublesen órganos perennes de nogal [(Carya illinoiensis(Wangenh.) Koch)]

Seasonal changes in soluble sugar concentration in pecan perennial organs(Carya illinoiensis[Wangenh.] Koch)

Luis Manuel Valenzuela Núñez EDWIN AMIR BRICEÑO CONTRERAS JUAN RAMON ESPARZA RIVERA María Cristina García de la Peña GEREMIAS RODRIGUEZ BAUTISTA (2019)

El transporte de azúcares de tejidos de asimilación a tejidos de reserva determina el crecimiento o el almacenamiento reproductivo vegetal. El objetivo fue determinar las concentraciones de azúcares solubles en nogal pecanero crecidos en una huerta ubicada en Torreón, Coahuila, durante las etapas de producción y letargo. Se tomaron muestras de raíz, tallo, rama y brote emitido del año (crecimiento anual) en cuatro árboles adultos. Durante el letargo se observaron mayores concentraciones de azúcares solubles que durante la etapa de producción. La raíz y los brotes anuales tuvieron concentraciones similares, más altas que los otros dos órganos. La menor concentración se encontró siempre en las ramas. El tallo presentó una concentración similar a las ramas durante la etapa de producción, mientras que, en la etapa de letargo, el tallo tuvo mayor concentración de azúcares que las ramas. A pesar de que la raíz presenta las mayores concentraciones de azúcares solubles, el tallo, por su tamaño, acumula la mayor cantidad de azúcares totales a nivel de todo el árbol. Se estimó que el porcentaje de los azúcares solubles del total del carbono contenido en la biomasa representa un valor porcentual de 66%

Transport of sugars from assimilation tissues to reserve tissues determines growth or reproductive storage. The objective wasto determine the concentrations of soluble sugars in pecan tree grown in an orchard located in Torreón, Coahuila, during the stages of production and dormancy. Samples of root, stem, branch, and bud emitted from the year (annual growth) were taken from fouradult trees. During the dormancy higher concentrations of soluble sugars were observed than during the production stage. Rootand annual outbreaks had similar concentrations, higher than the other two organs. The lowest concentration was always found in branches. Stem had a concentration similar to the branches during the production stage, while in the dormant stage, the stem had ahigher concentration of sugars than the branches. Although the root has the highest concentrations of soluble sugars, the stem, by its size, accumulates the greatest amount of total sugars in the whole tree. It was estimated that the percentage ofsolublesugars of the total carbon contained in the biomass represents a percentage value of 66%.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA Carbohidratos Frutales Fenología Carbono Carya illinoiensis Carbohydrates Fruit trees Phenology Carbon Carya illinoiensis

Potencial de secuestro de carbono y la eficiencia intrínseca del uso del agua de una huerta de nogal pecanero del Norte de México

ROBERTONI VÁZQUEZ FARRERA (2009)

"Se utilizó el método de la covarianza eddy para realizar mediciones de flujo de calor sensible, calor latente y flujo de bióxido de carbono (CO2) sobre el dosel de una huerta de nogal pecanero del Norte de México. También se obtuvo la radiación neta, flujo de calor en la superficie del suelo y la energía almacenada vii en la capa de aire y vegetación (de la superficie a la altura promedio de los árboles). Con esta información se obtuvo el balance de energía sobre el dosel de los árboles, la lámina de agua diaria evapotranspirada, el intercambio neto de bióxido de carbono entre el ecosistema (suelo – vegetación) de la huerta de nogal (NEE) y la eficiencia intrínseca del uso del agua por el ecosistema vege tal. Los resultados de la investigación indicaron que La huerta de nogal evalua da mostró un alto potencia de secuestro de carbono, ya que la asimilación de CO2 por el ecosistema (NEE durante el día) fue aproximadamente 3 veces ma yor que la liberación (NEE durante la noche). El valor de la retención promedio diaria (mayo a julio) de CO2 se obtuvo por la diferencia entre el NEE durante el día y el NEE durante la noche, y fue de -303.51 mmol CO2 m2. Esto correspon dió a 36.4 kg C ha-1 d-1 y considerando que el ciclo de mayor crecimiento es de mayo a septiembre (150 días), se tendría una retención de 5.46 t C ha-1 por ci clo de crecimiento. Este valor mostró la alta capacidad de secuestro de carbono que tiene este ecosistema, ya que fue aproximadamente igual a la tasa de re tención de carbono de un bosque boreal (39 kg C ha-1 d-1), pero mucho mayor que el reportado para un bosque de abeto negro (0.21 t C ha-1 a-1), ambos en Canada. La mayor retención de carbono del ecosistema se relacionó más con valores menores de respiración nocturna, que con valores altos de asimilación integrada durante el día. La tasa de respiración nocturna estuvo linealmente re lacionada con el incremento de la temperatura foliar. La eficiencia intrínseca del uso del agua (EUA) por el ecosistema fue de aproximadamente 2 mmolCO2 molH2O-1 valor mayor que el observado en un viii bosque caducifolio (0.6135) y el de una sabana abierta (0.920), pero menor que el observado en un cultivo de cobertura completa. Para el rango de valores de evapotranspiración registrados en este estudio, se observó una relación lineal decreciente entre EUA y la lámina de agua evapotranspirada. "

"The eddy covariance method was used to make flux measurements of sensible and latent heat flux and carbon dioxide flux (CO2) above the canopy of an orchard of pecan nut of Northern Mexico. Net radiation, soil heat flux and the energy stored in the layer of air and vegetation (from the surface to the canopy height) was also measured. With this information, the energy balance above de canopy, the daily depth of water evapotranspirated, the carbon dioxide net ecosystem exchange (NEE) and the intrinsic water use efficiency by the ecosystem was obtained. The results of this study showed that the pecan nut orchard evaluated had a high potential of carbon sequestration, since the assi-milation of CO2 by the ecosystem (NEE at daytime) was approximately 3 times bigger than the release (NEE at nighttime). The average value of the daily car-bon retention by the ecosystem was obtained by the difference between NEE during daytime and NEE during nighttime and was of 303.51 mmolCO2 m2. This corresponded to 36.4 kg C ha-1 d-1, considering that the stage of main growth is from May to September (150 days) it was equivalent to 5.46 t C ha-1 per stage of growth. This value showed the potential of carbon sequestration of this ecosys-tem, since it was approximately equals to the rate of carbon retention of a boreal forest (39 kg C ha-1 d-1), but much higher than the one reported for a boreal black spruce forest (0.21 t C ha-1 a-1) both form Canada. The highest carbon re-tention by the ecosystem was more related with small values of dark respiration than with high values of carbon assimilation during daytime. The rate of dark respiration was linearly related with the increase of leaf temperature. The intrinsic water use efficiency (WUE) by the ecosystem was approx-imately 2 mmolCO2 molH2O-1, this value was higher than the one observed in a deciduous forest (0.6135) and open savanna (0.920), but smaller than the one observed in a crop of full cover. For the range of values of evapotranspi-ration registered in this study, a decreasing lineal relation between WUE and depth of water evapotranspirated was observed"

Master thesis

Nogal pecanero Agua Carbón CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA