Síntesi i caracterització d’azo compostos fotoisomeritzables orgànics com a components de sistemes cristall-líquid macromoleculars

Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2019, Tutors: Dolors Velasco Castrillo, Jaume Garcia AmorósSmart materials are having a great deal of attention due to their endless applications in a wide range of technological areas as artificial actuation. Specifically, photoactive materials are very attractive since light, the energy source needed for their triggering, is environmentally friendly, free and cheap. Azobenzene derivatives are the chromophores of common choice for the design of light-sensitive materials due to their reversible isomerisation. Indeed, the introduction of these particular organic chromophores into liquid-crystalline polymers enables the modulation of their macroscopic properties like, for instance, their dimensions and shape. The first part of this project has involved the design and synthesis of two novel azobenzene derivatives. The structural identity of the azo compounds prepared has been confirmed by means of IR and 1H NMR spectroscopies. Their mesomorphic and photochromic behaviour has been investigated by means of polarized optical microscopy and time-resolved UV-Vis spectroscopy. The second part of the TFG implied the integration of these chromophores into liquid single crystal elastomers (LSCEs), i.e. weakly cross-linked polymer networks exhibiting a macroscopic orientation of the directors. As a whole, our LSCEs consist of a photoactive azobenzene-based monomer, a cross-linker and a mesogen. The introduction of an additional alkoxyphenyl comonomer has been considered in order to modulate the mesophase-to-isotropic phase transition temperature of the final material. Such feature is expected to pave the way to achieve photoactuating materials which can be operated under ambient conditions. All LSCEs have been prepared via the spin casting technique in three steps developed by Finkelmann and collaborators and further characterised by means of several techniques such as polarised optical microscopy, swelling experiments, differential scanning calorimetry and x-ray diffractio

Electrodeposited Ni-rich Ni-Pt mesoporous nanowires for selective and efficient formic acid-assisted hydrogenation of levulinic acid to γ-valerolactone

In pursuit of friendlier conditions for the preparation of high-value biochemicals, we developed a catalytic synthesis of -valerolactone by levulinic acid hydrogenation with formic acid as the hydrogen source. Both levulinic and formic acid are intermediate products in the biomass transformation processes. The objective of the work is two-fold; development of a novel approach for milder synthesis conditions to produce -valerolactone and the reduction of the economic cost of the catalyst. Ni-rich Ni-Pt mesoporous nanowires were synthesized in an aqueous medium using a combined hard-soft template-assisted electrodeposition method, in which porous polycarbonate membranes controlled the shape, and the pluronic P-123 copolymer served as the porogen agent. The electrodeposition conditions selected favored nickel deposition and generated nanowires with nickel percentages above the 75 at. %. The increase in deposition potential favored nickel deposition. However, it was detrimental for the porous diameter, because the mesoporous structure is promoted by the presence of the platinum-rich micelles near the substrate, which is not favored at the more negative potentials. The prepared catalysts promoted the complete transformation to -valerolactone in a yield of around 99% and proceeded with the absence of by-products. The couple temperature and reaction time were optimized considering the energy cost. The threshold operational temperature was established at 140 ºC, at which, 120 minutes were sufficient for attaining the complete transformation. Working temperatures below 140 ºC rendered the reaction completion difficult. The Ni78Pt22 nanowires exhibited excellent reusability, with minimal nickel leaching into the reaction mixture, whereas those with higher nickel contents showed corrosion

Electrodeposition of mesoporous Ni-rich Ni-Pt films for highly efficient methanol oxidation

The use of soft templates for the electrosynthesis of mesoporous materials has shown tremendous potential in energy and environmental domains. Among all the approaches that have been featured in the literature, block copolymer-templated electrodeposition had robustness and a simple method, but it practically cannot be used for the synthesis of mesoporous materials not based on Pt or Au. Nonetheless, extending and understanding the possibilities and limitations of block copolymer-templated electrodeposition to other materials and substrates is still challenging. Herein, a critical analysis of the role of the solution's primary electroactive components and the applied potential were performed in order to understand their influences on the mesostructure of Ni-rich Ni-Pt mesoporous films. Among all the components, tetrahydrofuran and a platinum (IV) complex were shown to be crucial for the formation of a truly 3D mesoporous network. The electrosynthesized well-ordered mesoporous Ni-rich Ni-Pt deposits exhibit excellent electrocatalytic performance for methanol oxidation in alkaline conditions, improved stability and durability after 1000 cycles, and minimal CO poisoning

Simple environmentally-friendly reduction of 4-nitrophenol

Abstract: 4-nitrophenol is a low molecular-mass organic compound involved in many chemical processes and commonly present in soils and in surface and ground waters, thereby causing severe environmental impact and health risk. Several methods have been proposed for its transformation (bio and chemical degradation). However, these strategies not only produce equally or more toxic aromatic species but also require harsh operating conditions and/or time-consuming treatments. In this context, we report a comprehensive and systematic study of the electrochemical reduction of 4-nitrophenol as a viable alternative. We have explored the electrochemical reduction of this pollutant over different metallic and carbonaceous substrata. Specifically, we have focused on the use of gold and silver working electrodes since they combine a high electrocatalytic activity for 4-nitrophenol reduction and a low electrocatalytic capacity for hydrogen evolution. The influence of the pH, temperature, and applied potential have also been considered as crucial parameters in the overall optimization of the process. While acidic media and high temperatures favor the clean reduction of 4-nitrophenol to 4-aminophenol, simultaneous hydrogen evolution results pernicious for this purpose. As a whole, a simple and effective electrochemical method for the transformation of 4-nitrophenol into 4-aminophenolis proposed with virtually no undesired by-products

Hybrid Ni@ZnO@ZnS-Microalgae for circular economy: A smart route to the efficient integration of solar photocatalytic water decontamination and bioethanol production

Water remediation and development of carbon-neutral fuels are priority objectives of our evermore industrialized society. The answer to these challenges should be simple, sustainable, and inexpensive. Thus, biomimetic-inspired circular and holistic processes combing water remediation and biofuel production can be an appealing concept to deal with these global issues. A simple circular approach using helical Spirulina platensis microalgae as biotemplates to synthesize Ni@ZnO@ZnS photocatalysts for efficient solar water decontamination and bioethanol production during the recycling process is presented. Under solar irradiation, the Ni@ZnO@ZnS-Spirulina photocatalyst exhibited enhanced activity (mineralization efficiency > 99%) with minimal photocorrosion and excellent reusability. At the end of its effective lifetime for water remediation, the microalgae skeleton (mainly glycogen and glucose) of the photocatalyst was recycled to directly produce bioethanol by simultaneous saccharification and fermentation process. An outstanding ethanol yield of 0.4 L kg-1, which is similar to the highest yield obtained from oxygenic photosynthetic microorganisms, was obtained. Thus, the entire process allows effective solar photocatalytic water remediation and bioethanol production at room temperature using simple and easily scalable procedures that simultaneously fixes carbon dioxide, thereby constituting a zero-carbon-emission circular process

QUIJOTE scientific results - VIII. Diffuse polarized foregrounds from component separation with QUIJOTE-MFI

We derive linearly polarized astrophysical component maps in the Northern Sky from the QUIJOTE-MFI data at 11 and 13?GHz in combination with the Wilkinson Microwave Anisotropy Probe K and Ka bands (23 and 33?GHz) and all Planck polarized channels (30-353-GHz), using the parametric component separation method B-SeCRET. The addition of QUIJOTE-MFI data significantly improves the parameter estimation of the low-frequency foregrounds, especially the estimation of the synchrotron spectral index, [beta]s. We present the first detailed ?s map of the Northern Celestial Hemisphere at a smoothing scale of 2°. We find statistically significant spatial variability across the sky. We obtain an average value of ?3.08 and a dispersion of 0.13, considering only pixels with reliable goodness of fit. The power-law model of the synchrotron emission provides a good fit to the data outside the Galactic plane but fails to track the complexity within this region. Moreover, when we assume a synchrotron model with uniform curvature, cs, we find a value of cs = ?0.0797 ± 0.0012. However, there is insufficient statistical significance to determine which model is favoured, either the power law or the power law with uniform curvature. Furthermore, we estimate the thermal dust spectral parameters in polarization. Our cosmic microwave background, synchrotron, and thermal dust maps are highly correlated with the corresponding products of the PR4 Planck release, although some large-scale differences are observed in the synchrotron emission. Finally, we find that the ?s estimation in the high signal-to-noise synchrotron emission areas is prior-independent, while, outside these regions, the prior governs the [beta]s estimation.We thank the staff of the Teide Observatory for invaluable assistance in the commissioning and operation of QUIJOTE. The QUIJOTE experiment is being developed by the Instituto de Astrofisica de Canarias (IAC), the Instituto de Fisica de Cantabria (IFCA), and the Universities of Cantabria, Manchester, and Cambridge. Partial financial support was provided by the Spanish Ministry of Science and Innovation under the projects AYA2007-68058-C03-01, AYA2007- 68058-C03-02, AYA2010-21766-C03-01, AYA2010-21766-C03-02, AYA2014-60438-P, ESP2015-70646-C2-1-R, AYA2017-84185-P, ESP2017-83921-C2-1-R, AYA2017-90675-REDC (co-funded with EU FEDER funds), PGC2018-101814-B-I00, PID2019-110610RBC21, PID2020-120514GB-I00, IACA13-3E-2336, IACA15-BE3707, EQC2018-004918-P, the Severo Ochoa Programs SEV-2015- 0548 and CEX2019-000920-S, the Maria de Maeztu Program MDM2017-0765, and by the Consolider-Ingenio project CSD2010-00064 (EPI: Exploring the Physics of Inflation). We acknowledge support from the ACIISI, Consejeria de Economia, Conocimiento y Empleo del Gobierno de Canarias, and the European Regional Development Fund (ERDF) under grant with reference ProID2020010108. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement number 687312 (RADIOFOREGROUNDS). EdlH acknowledges financial support from the Concepcion´ Arenal Programme of the Universidad de Cantabria. DT acknowledges the support from the Chinese Academy of Sciences (CAS) President’s International Fellowship Initiative (PIFI) with grant no. 2020PM0042. FP acknowledges support from the Spanish State Research Agency (AEI) under grant number PID2019-105552RB-C43. The authors acknowledge the computer resources, technical expertise, and assistance provided by the Spanish Supercomputing Network (RES) node at Universidad de Cantabria. Some of the presented results are based on observations obtained with Planck (http://www.esa.int/Planck), an ESA science mission with instruments and contributions directly funded by ESA Member States, NASA, and Canada. We acknowledge the use of the Legacy Archive for Microwave Background Data Analysis (LAMBDA) and the Planck Legacy Archive (PLA). Support for LAMBDA is provided by the NASA Office of Space Science. Some of the results in this paper have been derived using the HEALPIX package (Gorski ´ et al. 2005), and the HEALPY (Zonca et al. 2019), NUMPY (Harris et al. 2020), EMCEE (ForemanMackey et al. 2013), and MATPLOTLIB (Hunter 2007) PYTHON packages

The new multi-frequency instrument (MFI2) for the QUIJOTE facility in Tenerife

The QUIJOTE (Q-U-I joint Tenerife) experiment combines the operation of two radio-telescopes and three instruments working in the microwave bands 10?20 GHz, 26-36 GHz and 35-47 GHz at the Teide Observatory, Tenerife, and has already been presented in previous SPIE meetings (Hoyland, R. J. et al, 2012; Rubiño-Martín et al., 2012). The Cosmology group at the IAC have designed a new upgrade to the MFI instrument in the band 10-20 GHz. The aim of the QUIJOTE telescopes is to characterise the polarised emission of the cosmic microwave background (CMB), as well as galactic and extra-galactic sources, at medium and large angular scales. This MFI2 will continue the survey at even higher sensitivity levels. The MFI2 project led by the Instituto de Astrofísica de Canarias (IAC) consists of five polarimeters, three of them operating in the sub-band 10?15 GHz, and two in the sub-band 15-20 GHz. The MFI2 instrument is expected to be a full two-three times more sensitive than the former MFI. The microwave complex correlator design has been replaced by a simple correlator design with a digital back-end based on the latest Xilinx FPGAs (ZCU111). During the first half of 2019 the manufacture of the new cryostat was completed and since then the opto-mechanical components have been designed and manufactured. It is expected that the cryogenic front-end will be completed by the end of 2022 along with the FPGA acquisition and observing system. This digital system has been employed to be more robust against stray ground-based and satellite interference, having a frequency resolution of 1 MHz.The MFI2 instrument is being developed by the Instituto de Astrofisica de Canarias (IAC), with an instrumental participation from the Universidad Politecnica de Cartagena (UPCT). Partial financial support is provided by the Spanish Ministry of Science and Innovation (MICINN), under the projects AYA2017-84185-P, IACA15-BE-3707, EQC2018-004918-P and the FEDER Agreement INSIDE-OOCC (ICTS-2019-03-IAC-12). We also acknowledge financial support of the Severo Ochoa Programs SEV-2015-0548 and CEX2019-000920-S

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Recycled cyanobacteria ashes for sono-enhanced photo-Fenton wastewater decontamination

Currently, there is massive generation of persistent organic pollutants, which are hazardous sub-stances, owing to the exponential industrial growth and the associated waste production. Conse-quently, green and reliable strategies for decontaminating wastewater and generating value-added products are needed to realize the global demand of sustainability. In this study, an efficient sustain-able circular process for water remediation with nearly zero residue production is developed using iron-rich cyanobacteria ashes. These cyanobacteria ashes are obtained from the combustion of Ar-throspira platensis var lonar and are used as Fenton-like photocatalysts in different assisted photo-Fenton reactions (processes enhanced by light). The use of these iron-rich cyanobacteria ashes is par-ticularly effective for the sono-enhanced photo-Fenton processes for water remediation (mineraliza-tion > 94.9%), with an outstanding reusability. At the end of the effective lifetime of the photocata-lyst, the remaining ashes can be subsequently reused as a supplement during the growth of new cy-anobacteria, thus closing the circular process. The proposed approach is a green and sustainable pro-cess integrating both carbon dioxide fixation and clean-water production aimed at attaining sustain-able development

Circular zero-residue process using microalgae for efficient water decontamination, biofuel production, and carbon dioxide fixation

Microalgae can be easily integrated into an effective and scalable zero-carbon-emission circular process that exploits their CO2 fixation and wastewater remediation capabilities while simultaneously using their residues as an energy and biofuel source to power global sustainable development. Herein, the use of glycogen-rich Arthrospira platensis microalgae for efficient water decontamination, biofuel production, and CO2 fixation is explored. The circular process is initiated by efficient bioremediation of heavy metals (removal >99%) during microalgal growth, followed by bioethanol production, pellet production, and mineralization of persistent organic pollutants from wastewater, and is accompanied by CO2 fixation and/or oxygen production. Microalgal biomass generated during heavy metal bioremediation is used to produce bioethanol via simultaneous saccharification and fermentation (0.4 L per kg of dried microalgal biomass). The residual biomass obtained after bioethanol production is dried and compressed into pellets for its use as a fuel in biomass boilers (calorific power = 20.6 ± 0.2 MJ kg−1). The iron-rich ashes produced during pellet combustion are subsequently used as heterogeneous re-usable Fenton- like catalysts for the photo-Fenton degradation (mineralization >99%) of persistent organic pollutants. Finally, the low-activity ashes are incorporated into an ash-based medium for the efficient cultivation of microalgae. For each proposed step, product characterization and evaluation were conducted to optimize and enhance the process performance while minimizing negative effects on the environment