Graphene nanoplatelet reinforced concrete for self-sensing structures – A lifecycle assessment perspective

Concrete is the most widely used construction material, however, concrete structures often suffer from poor durability and require frequent inspections and repairs. Concrete production is also associated with high carbon emissions and the large-scale depletion of natural resources. Recently, the addition of graphene nanoplatelets (GNPs) in cementitious materials has shown a potential to improve the performance and instigate additional functionalities. However, there is limited understanding around the environmental effects from the production of GNP and its incorporation in concrete. This study has investigated, by means of a Life Cycle Assessment (LCA), the environmental impact of concrete reinforced with graphene nanoplatelets by focusing on the “cradle-to-gate” of GNP production and their incorporation in concrete. The production of 1 kg of G2NanPaste (GNPs product) is found to result in 0.17 kgCO2 equivalent units which is lower than Portland cement (0.86 kgCO2 eq). Ordinary Portland cement (CEM I) is 248 times more damaging than G2NanPaste in terms of global warming. The superplasticiser addition is found to have a greater environmental impact compared to G2NanPaste. The sensitivity analysis showed that if the addition of GNPs results in a 5% reduction of the Portland cement, the effect of the concrete mix on global warming can be reduced by 21%. This indicates that GNPs could be environmentally friendly if used as a supplement for some of the cement. The main aim of this paper is to perform the first LCA of the addition of graphene nanoplatelets in concrete. It is hoped that this work will pave the way for further research in this area.Costain Group plc

Public transport accessibility model based on user experience of the urban context

Los desafíos de transporte urbano poseen importantes aspectos técnicos y geográficos, pero éstas son solo dimensiones parciales de la problemática urbana. Para diseñar sistemas de transporte que rompan con los modelos tradicionales se necesita darle un giro más humano a la movilidad, ya que todos los viajes comienzan y terminan con una distancia recorrida a pie. En tal sentido, la calidad del ambiente urbano que rodea las áreas de acceso al Transporte Público (TP) influye en la captación de pasajeros, determinando la experiencia que los usuarios tendrán en los segmentos de acceso, transición y egreso del modo elegido. Este trabajo tiene como objeto elaborar una metodología para evaluar la accesibilidad a sistemas de TP. Se presentan los resultados preliminares del desarrollo de un modelo que intenta ampliar el alcance de las herramientas existentes de análisis, al brindar un marco metodológico a escala humana y desarrollar indicadores que describan cualidades experienciales. Se propone un modelo matemático de regresión ogística de seis variables predictivas, tres de ellas se refieren a aspectos materiales del viaje y tienen en cuenta la infraestructura urbana en diferentes escalas; otras tres se refieren a la experiencia de usuario que deriva de la interacción con el ambiente construido donde se produce el viaje.Mobility and transportation challenges in globalized cities have strong technical and locational facets, but these are only partial dimensions of the problematic. In order to design transportation systems that defy conventional models, a more humane shift towards mobility is needed, understanding that every trip starts and ends with a distance traveled by foot. Within this scope, the urban environment around public transport access areas influences catchment buffer distances, determined by the user experience during the access, transition and egress segments of the trip. This research aims to elaborate a methodological framework to evaluate accessibility that widens the scope of existing analysis tools. The preliminary results of a human-scale accessibility model are presented, elaborating on descriptive indicators of experiential qualities. The Logistic Regression mathematical model used consists of six predictive variables. Three of them describe the material aspects of the trip in different urban scales and the other three account for the user experience that derives from his interaction with the surrounding environment.Fil: Barón, Gabriela N.. Consejo Nacional de Investigaciones Científicas y TécnicasFil: Allende, David G..Fil: Arena, Alejandro P.

Comparative Analysis of Multiplicity Distributions in Inelastic Processes for Different Colliding Particles and Nuclei

Theoretical prediction of oscillations of cumulant moments of parton multiplicity distributions inside a jet supported by experimental data in some multiple production processes asks for analysis of the phenomenon for the whole set of available reactions. We have found out that the oscillations persist in any kind of processes and increase for particles with more complicated structure i.e. in the order of ee, eh, hh, hA, AA. The effect is not strongly dependent on the available phase space. Theoretical values of moments for quark and gluon jets up to 5th rank are shown. Zeros of the truncated generating function and singularities of the total generating function are discussed.Comment: revised version -- no changes in the text, corrected 3 references; 10 pages, 4 Postscript figure

Niveles de monóxido de carbono en el aire urbano de San Miguel de Tucumán, Argentina

Carbon monoxide, a highly toxic gas, is one of the most common and widely distributed air pollutants; in San Miguel de Tucumán, Argentina, the main sources of emission are the vehicle engines and the fire produced by the burning of cane fields. The objective was to evaluate the local levels of carbon monoxide (CO) concentration in the urban air of San Miguel de Tucumán during a period of 13 years. Four monitoring stations with high population concentration were selected. Testo 625 measuring instruments with specific probe for CO were used. The measure-ments were made during the months of September, October and November during the period 2003-2015. The concentrations of CO were compared using Variance analysis of Kruskal & Wal-lis and Conover post-test at 5 % significance. Minimum, maximum and Percentiles values (P25, P50 and P75) were considered. Results: No significant differences were observed in annual CO concentrations (p = 0.7177), with min = 24ppm, P25 = 28 ppm, P50 =28.9 ppm, P75 = 32 ppm and maximum = 38 ppm. With significant differences in CO concentrations (p <0.001) according to month and sampling season, higher values were detected in the month of November in Station 4 with min=27.0ppm, P25=30.7 ppm, P50=31.0 ppm, P75=33.2 ppm and maximum=38.0 ppm. Conclusion: The City of San Miguel de Tucumán is located in a mountainous area with little air movement, which means it has a notable accumulation of atmospheric pollutants, with high concentrations of CO in the microcenter of this city.El monóxido de carbono (CO), gas altamente tóxico, es uno de los contaminantes atmosféricos más comunes y ampliamente distribuidos. En San Miguel de Tucumán, Argentina, las principa-les fuentes de emisión son los motores de vehículos y los incendios producidos por la quema de cañaverales. El objetivo de la presente investigación fue evaluar los niveles locales de concen-tración de CO en el aire urbano de San Miguel de Tucumán durante un período de trece años. Se seleccionaron cuatro estaciones de monitoreo con alta concentración poblacional. Se emplearon instrumentos de medición Testo 625, con sonda específica para CO. Las mediciones se realizaron en los meses de septiembre, octubre y noviembre durante el período 2003-2015. Las concen-traciones de CO se compararon empleando análisis de la varianza de Kruskal-Wallis y postest de Conover al 5 % de significación. Se consideraron valores mínimos, máximos y percentiles P25, P50 y P75. Resultados: No se observaron diferencias significativas en las concentraciones anuales de CO (p = 0,7177), con min = 24 ppm, P25 = 28 ppm, P50 = 28,9 ppm, P75 = 32 ppm y máximo = 38 ppm. Con diferencias significativas en las concentraciones de CO (p < 0,001), se-gún mes y estación de muestreo. Los mayores valores fueron detectados en el mes de noviembre en Estación 4, con min = 27,0 ppm, P25 = 30,7 ppm, P50 = 31,0 ppm, P75 = 33,2 ppm y máximo = 38,0 ppm. La ciudad de San Miguel de Tucumán se encuentra en zona montañosa, con escaso movimiento de aire, lo que determina una marcada acumulación de contaminantes atmosféricos, con concentraciones de CO elevadas en el microcentro de esta ciudad.Biotecnologí

Hyaluronic acid modulates growth, morphology and cytoskeleton in embryonic chick skin fibroblasts

The action that hyaluronic acid (HA) exerts on cell proliferation was investigated in embryonic chick skin fibroblasts at different ages (7-14 days) and in different cell-cycle stages evaluated by flow cytometry (cells maintained with and without serum). Proliferation was estimated by 3H- thymidine incorporation and cell counting. The results demonstrated hyaluronic acid inhibits cell multiplication in all different environmental conditions examined. The inhibitory effect of HA is more evident in 14-day than 7-day old fibroblasts. The ability of HA to modulate 3H-thymidine incorporation did not involve a change in the time required for cells entering the S phase of the replicating cycle, but is due to a smaller number of cells entering in this phase. As the relationships between components of the extracellular matrix (ECM) and the cytoskeleton are known, parallel studies were carried out on some cytoskeleton proteins. Furthermore, by modifying the capacity of cells to adhere to the substrate, HA induced alterations in cell shape and in cytoskeleton components involved in these processes. We may hypothesize that HA, binding specific membrane receptors, affects cell adhesion and morphology inducing less receptivity of fibroblasts to mitogenic stimuli by transmembrane interactions with cytoskeleton

Small bodies science with the Twinkle space telescope

© 2019 Society of PhotoOptical Instrumentation Engineers (SPIE). Twinkle is an upcoming 0.45-m space-based telescope equipped with a visible and two near-infrared spectrometers covering the spectral range 0.4 to 4.5 μm with a resolving power R 250 (λ 2.42 μm). We explore Twinkle's capabilities for small bodies science and find that, given Twinkle's sensitivity, pointing stability, and spectral range, the mission can observe a large number of small bodies. The sensitivity of Twinkle is calculated and compared to the flux from an object of a given visible magnitude. The number, and brightness, of asteroids and comets that enter Twinkle's field of regard is studied over three time periods of up to a decade. We find that, over a decade, several thousand asteroids enter Twinkle's field of regard with a brightness and nonsidereal rate that will allow Twinkle to characterize them at the instrumentation's native resolution with SNR > 100. Hundreds of comets can also be observed. Therefore, Twinkle offers researchers the opportunity to contribute significantly to the field of Solar System small bodies research

Screening of antioxidant potentials and bioactive properties of the extracts obtained from two Centaurea L. species (C. kroumirensis coss. and C. sicula L. subsp sicula)

Herbal medicines, dietary supplements, or infusions with health promoting effects can note strong consumer demand. Hence, researchers and scientists have been increasingly focusing on the promotion of medicinal plants. In this respect, the present study has the evaluation of the biological properties of different extracts (hexane, chloroform, methanol, ultrasonic, essential oil, and supercritical) obtained from two Centaurea species (C. kroumirensis (Coss.) and C. sicula L. subsp sicula) as purpose. Antioxidative activities were assessed by in vitro assays including total phenolic content, free radical scavenging assay and ferric ion reducing power. Among the fourteen extracts examined, the highest total phenolic content (TPC) and antioxidant abilities were recorded in ultrasonic ethanol extracts of both Centaurea species. Additionally, these extracts exhibited a noticeable strong protective effect of the human skin fibroblast cell line (HS-68) that was exposed to oxidative stress induced by hydrogen peroxide. According to our results, the sonication with ethanol might be an ideal, rapid, and eco-friendly extraction method for obtaining a polyphenol-rich extract that exhibited high antioxidant activity. The results presented herein suggest that Centaurea species could be promoted as an antioxidant resource that could be exploited for the development of nutraceuticals or in pharmacology industry

Calibration standars of nuclear microprobes

El Micro-haz de iones Pesados (MiP) del laboratorio Tandar constituye un instrumento de características únicas en el país, pues puede proveer haces de iones pesados de dimensiones micrométricas acelerados hasta decenas de MeV de energía. La búsqueda de tamaños de haz más pequeños ha creado la necesidad de contar con estándares de calibración de elevada calidad de resolución. En el presente trabajo se desarrollaron los primeros prototipos para calibrar la focalización del haz: estructuras metálicas de cobre o niquel en forma de grilla con orificios cuadrados. Se emplearon dos métodos de fabricación. En el primero se utilizaron técnicas de fotolitografía convencional sobre un sustrato de silicio con foto-resina, mientras que en el segundo se utilizó el MiP para micro-mecanizar sustratos de Niobato de Litio (LiNbO3). En ambos casos se finalizó el proceso de fabricación del patrón con electrodeposición de cobre o níquel sobre la matriz desarrollada. Mediante la técnica fotolitográfica se fabricaron grillas de níquel que varían entre 130 y 180 mesh**. Mediante micro-mecanizado con el MiP se fabricaron grillas de cobre de entre 500 y 2000 mesh sobre sustratos de LiNbO3.The Micro-heavy ion beam (MiP) at Tandar’s Lab is a unique instrument in the country, as it can provide heavy ion beams at micrometer-scale accelerated to tens of MeV energy. The quest for smaller beam sizes has created the need for calibration standards of high resolution quality. In this paper we developed the first prototypes to calibrate the beam focusing: metal structures of copper or nickel shaped grid with square holes. We used two methods of manufacture. Were used in the first conventional photolithography techniques on a silicon substrate with photoresin while the second was used for micromachining with MiP substrates of lithium niobate (LiNbO3). In both cases the process for the manufacture was finished with electro-deposition of copper or nickel on the matrix developed. By photolithographic technique nickel grids were manufactured varying between 130 and 180 mesh. By MiP micromachining copper grids were produced between 500 and 2000 mesh on LiNbO3 substrates.Fil: Arena, S.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Faya, T.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Lell, J.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; ArgentinaFil: Vega, N.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Davidson, Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Nesprias, Francisco Jose Gabriel. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Debray, M.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentin

Release experiments as an indicator of flying activities of stingless bees in urban areas

Contemporary urban ecology views cities as heterogeneous and dynamic ecosystems, composed of biotic, physical, social, and man-made systems. In this context, urban beekeeping stands out as a growing practice that demands further studies. Many species of stingless bees (tribe Meliponini) have adapted to urban areas, while others are more sensitive. The composition of the surroundings where the beehive is located is important for the health of the nests and quality of the bee products. This work used bee capture and release techniques to evaluate the use of this methodology for releasing and monitoring native bees in urban areas and to identify whether proportion of green and gray urban nature areas affect the flying activities of stingless bees in an urban landscape. We used nests of Melipona quadrifasciata (mandaçaia), a species of stingless bee native to the Atlantic Rainforest, from three meliponaries located in different parts of the city of São Paulo. The travel time of bees in the landscape were related to the green urban areas up to 900 m in diameter from the meliponaries. Although we did not find a relationship between green areas and bee return times and numbers, it was noticeable that there was variation between the study areas, indicating that the release and monitoring methodology can be used in urban areas following the recommended modifications