Laser-induced forward transfer of conductive nanoinks

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2021, Tutor: Juan Marcos Fernández PradasLaser-induced forward transfer (LIFT) is a noozle-free technique for printing materials presenting some advantages with respect to inkjet printing. LIFT of conductive nanoinks of high viscosity and particle content is explored in this work. The morphology and characteristics of the deposited material at different laser pulse repetition rates are analyzed. The improvement of electrical properties when applying several layers to the deposited material is studied, managing to obtain Rs = 3.5 mΩ/ when applying two layers. The gap dependence on the features of deposited material is investigated as well. Finally, as a proof of concept to develop electronic devices through LIFT of high viscosity inks, a resistance temperature detector is developed and characterize

Controlling light in scattering media using ultrasound modulation

Light-based methods are fundamental in biology and biomedical sciences. They allow for non-invasive diagnosis and localized treatments with resolutions down to the sub-cellular level. However, light scattering inside biological tissue constrains the maximum depth at which current methods can operate. In this work, we show that light can be focused and controlled in scattering media using ultrasound waves. We experimentally prove how ultrasound waves can work as embedded lenses in the scattering media, helping to compensate for scattering and redirect light toward a deeper focus. Our results demonstrate qualitatively and quantitatively how such ultrasound-enabled lenses enable up a factor of 7 improvement in light focusing for samples with a scattering coefficient of 3.5 1/mm, compared to traditional focusing with external elements. This allows to resolve images of test samples immersed in scattering media - USAF target with spacing of 27.8 um - that would be completely hidden with existing methods

Bose-Einstein condensates in a disordered potential: Anderson localization

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2017, Tutor: Ricardo MayolWe have simulated a Bose-Einstein condensate in a disordered potential, whose main characteristics such as the frequency of its maxima and its amplitude can be controlled through two parameters: the correlation length and the disorder strength. Studying the 1D case, we have encountered Anderson localization, which is the localization of individual particles or waves in a disordered energetic landscape, under specific parameters for both the interacting and the non-interacting regime. We have not been able to unambiguously observe the same kind of localization for 2D systems, although we provide an explanation for this result in terms of the topology of the 2D disordered potential, and interactions

Enhanced light focusing inside scattering media with shaped ultrasound

Light focusing is the primary enabler of various scientific and industrial processes including laser materials processing and microscopy. However, the scattering of light limits the depth at which current methods can operate inside heterogeneous media such as biological tissue, liquid emulsions, and composite materials. Several approaches have been developed to address this issue, but they typically come at the cost of losing spatial or temporal resolution, or increased invasiveness. Here, we show that ultrasound waves featuring a Bessel-like profile can locally modulate the optical properties of a turbid medium to facilitate light guiding. Supported by wave optics and Monte Carlo simulations, we demonstrate how ultrasound enhances light focusing a factor of 7 compared to conventional methods based on placing optical elements outside the complex medium. Combined with point-by-point scanning, images of samples immersed in turbid media with an optical density up to 15, similar to that of weakly scattering biological tissue, can be reconstructed. The quasi-instantaneous generation of the shaped-ultrasound waves, together with the possibility to use transmission and reflection architectures, can pave the way for the real-time control of light inside living tissue

Study of the influence of operational conditions and hollow-fiber diameter on the ultrafiltration performance of a secondary treatment effluent

Secondary treatment effluents from municipal wastewater treatment plants (MWWTP) must achieve high water quality standards for their reuse in agriculture. To achieve these standards, ultrafiltration (UF) process, which is economically feasible, is carried out. However, UF has a drawback, membrane fouling, which causes operating difficulties and an increment of the operating cost. In order to minimize this phenomenon, it is important to determine the best operational conditions. Wastewater samples provided by MWWTP have a lot of variability in their composition due to factors such as temperature, efficiency of the secondary treatment, etc. Besides, the soluble microbial products of the secondary effluent are dependent on the type of the biological treatment implemented and its operating conditions. A model wastewater feed solution was prepared consisting of 15 mg/L of bovine serum albumin and 5.5 mg/L of dextran. In this research, UF tests were performed with the optimal simulated wastewater using two membranes UFCM5 Norit X-flow® hollow-fiber: one of them with a fiber diameter of 1.5 mm and the other one with a fiber diameter of 0.8 mm. The operational conditions, which influence membrane fouling, were varied in the range of 62 100 kPa for transmembrane pressure (TMP) and in the range of 0.8 1.2 m/s for cross-flow velocity (CFV). The best operational conditions were selected in terms of higher permeate flux. The highest permeate flux was obtained for the membrane of 0.8 mm and the lower energy consumption was achieved at a CFV of 1.2 m/s and a TMP of 62 kPa.Torà Grau, M.; Soler Cabezas, JL.; Vincent Vela, MC.; Mendoza Roca, JA.; Martínez Francisco, FJ. (2015). Study of the influence of operational conditions and hollow-fiber diameter on the ultrafiltration performance of a secondary treatment effluent. Desalination and Water Treatment. 1-7. doi:10.1080/19443994.2015.1118887S1

Análisis comparativo del papel de la mujer en la revolución zapatista y en Rojava

Màster en Diplomàcia i Funció Pública Internacional, Centre d'Estudis Internacionals, Universitat de Barcelona, Curs: 2017-2018, Tutor: David Bondia Garcí

INTERVENCIÓN DE UNA PIEZA DE ÉPOCA IBÉRICA PROCEDENTE DE LA BASTIDA DE LES ALCUSSES (MOIXENT)

[ES] El tema que se aborda en el siguiente trabajo consta del proceso de inter - vención realizado según los criterios que todo buen profesional de la restau- ración debe seguir: respeto a la pieza sobre la que se actúa, reversibilidad de todos los materiales empleados en dicha intervención, y reconocimiento de la intervención respecto a la pieza original. Dicha intervención se ha realizado sobre una pieza arqueológica ibérica del siglo IV a. C. , procedente del yacimiento de la Bastida de les Alcusses de Moixent (Alicante) y perteneciente al depósito de piezas del Museo de Pre - historia de València. A continuación se expondrá el contexto histórico al que pertenece la pie - za, así como cada proceso realizado sobre esta, y por último se comentarán parámetros de conservación preventiva aplicados a la pieza. Dentro del tratamiento de la pieza se ha dado mucha importancia al pro- ceso de limpieza, ya que este ha permitido el buen estudio tanto de la pieza en sí como de su propia policromía.[EN] The topic addressed in this project follows the intervention process accor - ding to the criteria that every restoration professional should acknowledge: respect to the piece being intervened, reversibility over the materials emplo - yed on the intervention, and recognition of the intervention over the original piece. This particular intervention has been made over an Iberian archaeological piece from IV century BC, found at the deposit La Bastida de les Alcusses in Moixent (Alicante). The piece belongs to the collection of the Museo de Prehistoria de Valèn - cia (Valencia Prehistoric Museum). Below, the historical context of the piece will be presented, along with every intervention made and, finally, the parameters of preventative conser - vation applied to the piece. In relation to the treatment of the piece, the cleaning process has been fundamental, since it has allowed for a proper study of the piece, as well as the uncovering of its polychromy by the archaeologistTorà Vázquez, M. (2016). INTERVENCIÓN DE UNA PIEZA DE ÉPOCA IBÉRICA PROCEDENTE DE LA BASTIDA DE LES ALCUSSES (MOIXENT). http://hdl.handle.net/10251/74222.TFG

Efficient and automated start-up of a pilot reactor for nitritation of reject water : from batch granulation to high rate continuous operation

An automated sequencing batch reactor operation based on online measurement of the ammonium concentration was investigated as a tool for improving the start-up of a nitrifying granular airlift reactor. The effectiveness of this start-up procedure was verified with the characteristics of the developed granular sludge but also the improvement of the start-up was confirmed when comparing with the results achieved with two continuous-mode start-up strategies. Once a stable granular biomass was obtained, the reactor started to operate in continuous mode during more than 100 days, maintaining the characteristics of the granular biomass and achieving a nitrogen loading rate of 1.75 g N L⁻¹ d⁻¹. The intermittent recirculation of small flocs of nitrifying biomass was explored as an alternative to increase the biomass concentration in the reactor and consequently, to increase the treated loading rate

The effect of winds in red supergiants: modeling for interferometry

Red supergiants (RSGs) are evolved massive stars in a stage preceding core-collapse supernova. Understanding evolved-phases of these cool stars is key to understanding the cosmic matter cycle of our Universe, since they enrich the cosmos with newly formed elements. However, the physical processes that trigger mass loss in their atmospheres are still not fully understood, and remain one of the key questions in stellar astrophysics. We use a new method to study the extended atmospheres of these cold stars, exploring the effect of a stellar wind for both a simple radiative equilibrium model and a semi-empirical model that accounts for a chromospheric temperature structure. We then can compute the intensities, fluxes and visibilities matching the observations for the different instruments at the Very Large Telescope Interferometer (VLTI). Specifically, when comparing with the atmospheric structure of HD 95687 based on published VLTI/AMBER data, we find that our model can accurately match these observations in the Kband, showing the enormous potential of this methodology to reproduce extended atmospheres of RSGs.Comment: 6 pages, 5 figures, to appear at the Proceedings of the IAUS370: Winds of stars and exoplanets. Eds: A. Vidotto and M. Smith-Spanier. Based on a contributed talk on preliminary work from Gonz\'alez-Tor\`a et al., submitted to A&