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Control of the size distribution of AuNPs for colorimetric sensing by pulsed laser ablation in liquids
No full textGold nanoparticles (AuNPs) are extensively employed in colorimetric sensing, taking advantage of their optical properties to detect variables via observable color changes. These properties are primarily driven by localized surface plasmon resonance (LSPR), particularly pronounced in AuNPs within the visible spectrum. In this study, AuNPs were synthesized via pulsed laser ablation in liquids (PLAL) with a laser pulse energy (Ep) ranging from 25 mJ to 75 mJ. Size distributions, hydrodynamic diameters, polydispersity indices (PDI), absorbance intensity, and LSPR were characterized. Spherical AuNPs with FCC structure were synthesized, exhibiting a maximum absorption peak centered at approximately 529 nm wavelength and a size range between 50 nm and 178 nm, easily adjustable depending on the laser pulse energy used in the synthesis process. An anomalous behavior was noted at mJ, exhibiting three peaks in size distribution, high PDI, low absorbance intensity, and indistinct LSPR. By extending the ablation time from 10 min to 30 min, particle size decreased alongside lower PDI. Size distributions transitioned from three to two peaks, absorbance increased, and LSPR became readily identifiable. These findings underscore the size control over AuNP characteristics achievable through PLAL synthesis parameters, promising significant implications for the optimization of colorimetric sensor design and development
The ³Cat-4 Spacecraft Thermal Analysis and Thermal Vacuum Test Campaign Results
No full text³Cat-4 is the fourth member of the CubeSat series of UPC’s NanoSat Lab, and it was selected by the ESA Academy’s Fly Your Satellite! program in 2017. This mission aims at demonstrating the capabilities of nano-satellites, and in particular those based in the 1-Unit CubeSat standard, for challenging Earth Observation (EO) using Global Navigation Satellite System-Reflectometry (GNSS R) and L-band microwave radiometry, as well as for Automatic Identification Systems (AIS). The following study presents the results of the thermal analysis carried out for this mission, evaluating different scenarios, including the most critical cases at both high and low temperatures. The results consider different albedos and orbital parameters in order to establish the optimal temperatures to achieve the best mission performance within the nominal temperatures, and in all operational modes of the satellite. Simulation results are included considering the thermal performance of other materials, such as Kapton, as well as the redesign of the optical properties of the satellite’s solar panels. The correlation with the thermal model and the TVAC test campaign was conducted at the ESA ESEC GALAXIA facilities in Belgium
3Cat-8 Mission: A 6-Unit CubeSat for Ionospheric Multisensing and Technology Demonstration Test-Bed
No full textThis paper presents the mission analysis of 3Cat-8, a 6-Unit CubeSat mission being developed by the UPC NanoSat Lab for ionospheric research. The primary objective of the mission is to monitor the ionospheric scintillation of the aurora, and to perform several technological demonstrations. The satellite incorporates several novel systems, including a deployable Fresnel Zone Plate Antenna (FZPA), an integrated PocketQube deployer, a dual-receiver GNSS board for radio occultation and reflectometry experiments, and a polarimetric multi-spectral imager for auroral emission observations. The mission design, the suite of payloads, and the concept of operations are described in detail. This paper discusses the current development status of 3Cat-8, with several subsystems already developed and others in the final design phase. It is expected that the data gathered by 3Cat-8 will contribute to a better understanding of ionospheric effects on radio wave propagation and demonstrate the feasibility of compact remote sensors in a CubeSat platform
On the soil - structure interaction induced by shallow tunnelling in urban area
No full textAbstract:
To offer a prediction of the settlements that the building Palazzo Campana in the city center of Torino, Italy, is going to suffer during the excavation of the next Metro-Line 2 of Torino, various three dimensional numerical models are configured to analyze the greenfield, uncoupled and coupled interaction schemes of the tunnelling problem; providing parametrical analyses to encapsulate the possible behaviors that the structure could experience in-situ. In comparison to the existent Metro-Line 1 of Torino, Italy, which exclusively dug its way below three main and one secondary urban roads (C.so Francia, C.so Bolzano, C.so Vittorio Emanuele II and Via Nizza) reducing its direct interaction with surface structures and furthermore, avoiding completely the city’s historical center; the Metro-Line 2 phase 1 project (north alignment from Rebaudengo to Porta Nuova) poses a challenge in the sense that it foresees excavations directly passing below several buildings in the north of the city, towards the Aurora and Vanchiglia districts, with an especially long portion proceeding underneath historical masonry buildings in the Centro Storico (historical center) quarter of Torino. For this reason, both the City of Torino and its society Infratrasporti.To S.r.l., in charge of the preliminary designs of the works, supervision, in-situ surveys, feasibility studies and contract administration, are rightfully interested in guaranteeing the successful completion of the tunnelling works with negligeable effects on the surface structures. For this purpose, in the design stage the society studied the interaction between the excavation and the buildings on top of the tunnel path, and through simplified empirical and two dimensional numerical alternatives, they identified 11 buildings at risk of experiencing moderate to severe damage, from which only one building, Palazzo Campana, fell in the highest degree of severity. Acknowledging that simplified methods for building damage estimation are regarded as conservative, it is the motivation of the current thesis to evaluate such statement with more advanced methods, such as three-dimensional parametric numerical modelling, in an effort to provide more representative predictions of what the real tunnelling process will be, its interaction with Palazzo Campana and the potential building risk of damage
Efectos de las reformas a las políticas de formación de docentes en programas de filosofía en Colombia
No full textResumen:
Entre 2015 y 2017 se llevó a cabo en Colombia una reforma a las políticas de formación de maestros. Se analiza el proceso de implementación de dicha normatividad empleando la metodología de estudio de caso múltiple con cinco instituciones en Bogotá y se examinan las consecuencias que tuvo para estos programas: encarecimiento y reducción de estudiantes. Se evidencia que la implementación de la reforma estudiada desestimuló la formación de docentes en filosofía. Los cambios implementados evidenciaron fracturas en la legislación y un fracaso en la estrategia de mercantilización de la educación, pues en un contexto inequitativo como el colombiano, para resolver los problemas de la educación no es suficiente con regular el mercado educativo.
Abstract:
Between 2015 and 2017, a reform of teacher training policies was carried out in Colombia. The process of implementing this normativity is analyzed using the multiple case study methodology with five institutions in Bogota and the consequences for these programs are examined: higher prices and reduction of students. It is evident that the implementation of the studied reform discouraged the training of teachers in philosophy. The changes implemented showed fractures in the legislation and a failure in the strategy of commercialization of education, since in an inequitable context like the Colombian one, solving the problems of education is not enough to regulate the education market
Dendropsophus ebraccatus. Foto 2
No full textEn este individuo el dorso es completamente amarillo, con motas oscuras, que se extiende hasta los muslos, y la franja café dorsolateral presente.Preocupación menorLa tendencia poblacional de la especie es estable, dada su adaptabilidad a hábitats antrópicos. Sin embargo, la Unión Internacional para la Conservación de La Naturaleza (UICN) plantea amenazas a nivel local y se reportan individuos con infecciones causadas por un hongo (Batrachochytrium dendrobatidis)
Hyalinobatrachium tatayoi. Foto 2
No full textLas Ranas de Cristal reciben ese nombre por el vientre traslúcido que permite observar los órganos internos. En este caso, se alcanzan a apreciar los huesos y el peritoneo de color blanco. También se resaltan las membranas interdigitales (1) y discos digitales (2) redondeados.
(1) Las membranas interdigitales corresponden a la piel que se extiende entre los dedos de las manos y pies.
(2) Los discos digitales son terminaciones expandidas al final de los dedos.Preocupación menorLa tendencia poblacional de la especie es estable, además es tolerante a la intervención antrópica, por lo cual, no se identifican amenazas potenciales
Hyalinobatrachium tatayoi. Foto 5
No full textMasa de huevos gelatinosos puestos en la parte inferior (envés) de la hoja. Los huevos serán cuidados por uno de los parentales inmediantamente después de la puesta. Estas dos características (masa gelatinosa y cuidado parental) favorece la supervivencia de los embriones.Preocupación menorLa tendencia poblacional de la especie es estable, además es tolerante a la intervención antrópica, por lo cual, no se identifican amenazas potenciales
Culebra negra ciega
No full textSerpiente pequeña, con una longitud total que varía entre 35 y 60 mm. El cuerpo es cilíndrico, la cabeza, no diferenciada, es mas larga que ancha, y el hocico es prognato (1). Las escamas son lisas y el patrón de coloración del cuerpo se compone de bandas longitudinales que nacen en la cabeza, café oscuro y doradas. La cola es oscura uniforme. La escama rostral (2) y las de la punta de cola son amarillas. Se distribuye en el norte de Suramérica, específicamente en Colombia y Venezuela, por debajo de los 600 m. s. n. m. En Colombia se encuentra en la región biogeográfica del Caribe, y en el valle del río Magdalena.
(1) Prognato, que tiene saliente la mandíbula.
(2) La escama rostral está ubicada en el extremo anterior del hocico, en la maxila superior.Especie fosorial (1), con hábitos nocturnos y dieta insectívora (se alimenta de invertebrados), consumiendo principalmente hormigas o termitas. Su reproducción es ovípara.
(1) Fosorial, organismo de vida subterránea adaptado a excavar agujeros en el suelo.No evaluadaPreocupación menorLa tendencia poblacional de la especie es desconocida y no se han identificado amenazas potenciales.No evaluad
Gymnophthalmus speciosus. Foto 1
No full textVista superior de un individuo subadulto que se identifica por la coloración rojiza de la cola.También se aprecia la extremidad posterior más larga que la anterior.Preocupación menorLa tendencia poblacional de la especie es estable y no se han identificado amenazas potenciales