Cryogenic Ion Vibrational Spectroscopy of Gas-Phase Clusters: Structure, Anharmonicity and Fluxionality

Gas-phase clusters are aggregates of a countable number of particles, which exhibit size-dependent physical and chemical properties that typically lie in the non-scalable size regime. These properties can be systematically characterized at a molecular level with respect to composition, size and charge state. This allows studying how macroscopic properties of condensed matter, e.g. phase transitions or metallic behavior, emerge from the atomic or molecular properties as a function of cluster size. Furthermore, smaller clusters are also amenable to high-level quantum chemical calculations, making them ideal model systems for understanding phenomena in more complex heterogeneous matter. The main advantage here is that clusters can be studied with a very high degree of selectivity and sensitivity, under well-defined conditions and in the absence of perturbing interaction with an environment. The studies presented in this theses focus on the structure characterization of ionic clusters using cryogenic ion vibrational spectroscopy. This technique combines cryogenic ion trapping with mass spectrometric schemes and infrared photodissociation (IRPD) spectroscopy. It makes use of an ion-trap triple mass spectrometer in combination with various light sources that grant access to a wide range of the infrared spectrum (210-4000 cm-1). Structures are typically assigned by comparing experimental IRPD spectra with computed vibrational spectra. The structures of aluminum oxide clusters and their interaction with water are studied in the framework of the collaborative research center CRC1109 "Understanding of Metal Oxide / Water Systems at the Molecular Scale: Structural Evolution, Interfaces, and Dissolution". This project aims at gaining a molecular level understanding of the mechanisms involved in oxide formation and dissolution. Section 4.1 and 4.2 present results of IRPD spectroscopy experiments on small mono and dialuminum oxide anions and on the anionic cluster series (Al2O3)nAlO2- with n = 0 to 6. These studies discuss the effects of the distribution of the excess charge on the cluster structure, analyze how structural properties evolve with size and how these relate to those of nanoparticles and crystal surfaces. The dissociative adsorption of water by Al-oxide clusters is investigated in Section 4.3.2. Boron exhibits a rich variety of polymorphs with the B12 icosahedron as a common building block. This three dimensional (3D) structure is retained in the halogenated closo-dodecaborate dianions (B12X122-). On the other hand, small pure boron clusters are essentially planar. The study presented in Section 5.2 investigates the 3D to 2D structural transition by probing the vibrational spectra of partially deiodinated B12In2- clusters as a function of decreasing n. The results presented in Section 5.1 show that B13+ has a planar structure consisting of two concentric rings. As a result of delocalized aromatic bonding, this structure is particularly stable without being rigid as it permits an almost free rotation of the inner ring. Protonated water clusters are model systems for understanding protons in aqueous solutions. The interpretation of their vibrational spectra is a challenge for state-of-the-art electronic structure calculations and therefore often prone to controversies. The results presented in Chapter 6 clear existing doubts over the assignment of the protonated water pentamer structure and the vibrational fingerprints of the embedded distorted H3O+. This study laid the foundation for a subsequent series of measurements which provided crucial new insights into the proton transfer mechanism in water

PMI: A Delta Psi(m) Independent Pharmacological Regulator of Mitophagy

Mitophagy is central to mitochondrial and cellular homeostasis and operates via the PINK1/Parkin pathway targeting mitochondria devoid of membrane potential (ΔΨm) to autophagosomes. Although mitophagy is recognized as a fundamental cellular process, selective pharmacologic modulators of mitophagy are almost nonexistent. We developed a compound that increases the expression and signaling of the autophagic adaptor molecule P62/SQSTM1 and forces mitochondria into autophagy. The compound, P62-mediated mitophagy inducer (PMI), activates mitophagy without recruiting Parkin or collapsing ΔΨm and retains activity in cells devoid of a fully functional PINK1/Parkin pathway. PMI drives mitochondria to a process of quality control without compromising the bio-energetic competence of the whole network while exposing just those organelles to be recycled. Thus, PMI circumvents the toxicity and some of the nonspecific effects associated with the abrupt dissipation of ΔΨm by ionophores routinely used to induce mitophagy and represents a prototype pharmacological tool to investigate the molecular mechanisms of mitophagy

Modelling and nanofabrication of chiral dielectric metasurfaces

Polarization control through all-dielectric metasurfaces holds great potential in different fields, such as telecommunications, biochemistry and holography. Asymmetric chiral metasurfaces supporting quasi-bound states in the continuum may prove very useful for controlling and manipulating the polarization state of light. A crucial quantity for characterizing the optical chirality is the circular dichroism (CD). In this work we analyse how the CD and quality factor of the optical mode can be strongly influenced by a nanofabrication error. Modelling the nanofabrication uncertainties on the gaps of the chiral metasurface, the imperfections of the etchings process or the modification of the asymmetry factor, we found that the proper engineering of the gap between the nanostructures of the unit cell is the most important parameter to achieve a high-quality factor and enhanced optical dichroism. An optimization of the nanofabrication processes, such as dose factor, dwell time and plasma etching demonstrates that, for a writing field of 100 & mu;m2, it is possible to obtain morphologically precise chiral metasurfaces, with fabrication uncertainties lower than those that would limit Q factor and chirality property

The vibrational spectrum of FeO2+ isomers

Infrared photodissociation is used to record the vibrational spectrum of FeO2+(He)2–4 which shows three bands at 1035, 980, and 506 cm−1. Quantum chemical multi-reference configuration interaction calculations (MRCISD) of structures and harmonic frequencies show that these bands are due to two different isomers, an inserted dioxo complex with Fe in the +V oxidation state and a side-on superoxo complex with Fe in the +II oxidation state. These two are separated by a substantial barrier, 53 kJ/mol, whereas the third isomer, an end-on complex between Fe+ and an O2 molecule, is easily converted into the side-on complex. For all three isomers, states of different spin multiplicity have been considered. Our best energies are computed at the MRCISD+Q level, including corrections for complete active space and basis set extension, core-valence correlation, relativistic effects, and zero-point vibrational energy. The average coupled pair functional (ACPF) yields very similar energies. Density functional theory (DFT) differs significantly from our best estimates for this system, with the TPSS functional yielding the best results. The other functionals tested are BP86, PBE, B3LYP, TPSSh, and B2PLYP. Complete active space second order perturbation theory, (CASPT2) performs better than DFT, but less good than ACPF

Gas phase structures and charge localization in small aluminum oxide anions: Infrared photodissociation spectroscopy and electronic structure calculations

We use cryogenic ion trap vibrational spectroscopy in combination with quantum chemical calculations to study the structure of mono- and dialuminum oxide anions. The infrared photodissociation spectra of D2-tagged AlO1-4− and Al2O3-6− are measured in the region from 400 to 1200 cm−1. Structures are assigned based on a comparison to simulated harmonic and anharmonic IR spectra derived from electronic structure calculations. The monoaluminum anions contain an even number of electrons and exhibit an electronic closed-shell ground state. The Al2O3-6− anions are oxygen-centered radicals. As a result of a delicate balance between localization and delocalization of the unpaired electron, only the BHLYP functional is able to qualitatively describe the observed IR spectra of all species with the exception of AlO3−. Terminal Al–O stretching modes are found between 1140 and 960 cm−1. Superoxo and peroxo stretching modes are found at higher (1120-1010 cm−1) and lower energies (850-570 cm−1), respectively. Four modes in-between 910 and 530 cm−1 represent the IR fingerprint of the common structural motif of dialuminum oxide anions, an asymmetric four-member Al–(O)2–Al ring

Rol de la alantoina durante la maduración y germinación de la semilla de Arabidopsis thaliana

Fil: Martini, C. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Martini, C. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Lescano, I. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Lescano, I. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Fagiani, M. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Fagiani, M. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Devegili, A. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Devegili, A. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Desimone, M. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Desimone, M. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.La alantoina es un compuesto nitrogenado heterocíclico derivado de la vía de oxidación de las purinas que tiene un papel importante en la asimilación, metabolismo, transporte y almacenamiento de nitrógeno en plantas (Todd, 2006. J. Exp.Bot. 57: 5−12.). Numerosos estudios han demostrado una estrecha relación entre la activación de esta vía y procesos de aclimatación y respuesta a estrés biótico y abiótico (Alamillo, 2010. Plant Cell Environ. 33: 1828−1837.).Fil: Martini, C. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Martini, C. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Lescano, I. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Lescano, I. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Fagiani, M. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Fagiani, M. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Devegili, A. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Devegili, A. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Desimone, M. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Desimone, M. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Biología Celular, Microbiologí

Site-specific vibrational spectral signatures of water molecules in the magic H₃O⁺(H₂O)₂₀ and Cs⁺(H₂O)₂₀ clusters

Theoretical models of proton hydration with tens of water molecules indicate that the excess proton is embedded on the surface of clathrate-like cage structures with one or two water molecules in the interior. The evidence for these structures has been indirect, however, because the experimental spectra in the critical H-bonding region of the OH stretching vibrations have been too diffuse to provide band patterns that distinguish between candidate structures predicted theoretically. Here we exploit the slow cooling afforded by cryogenic ion trapping, alongwith isotopic substitution, to quench water clusters attached to the H3O+ and Cs+ ions into structures that yield well-resolved vibrational bands over the entire 215- to 3,800-cm−1 range. The magic H3O+ (H2O)20 cluster yields particularly clear spectral signatures that can, with the aid of ab initio predictions, be traced to specific classes of network sites in the predicted pentagonal dodecahedron H-bonded cage with the hydronium ion residing on the surface

Evaluation of tsunamigenic hazard through numerical modeling from seismic and non-seismic sources in the Crotone offshore (Calabria, Southern Italy)

Tsunamis in the Mediterranean Sea can be considered among the major sources of hazard, both for the extension of the area that can be involved by the water impact and for the closeness of potential sources to the coast, which reduces dramatically the alert and evacuation time. Moreover, landslides, as other non-seismic tsunami sources, are often characterized by a lack of precursors (such as seismic shaking), a reason for which the ensuing waves are sometimes called “surprise tsunamis”

Thick Does the Trick: Genesis of Ferroelectricity in 2D GeTe-Rich (GeTe)m(Sb2Te3)n Lamellae

The possibility to engineer (GeTe)m(Sb2Te3)n phase-change materials to co-host ferroelectricity is extremely attractive. The combination of these functionalities holds great technological impact, potentially enabling the design of novel multifunctional devices. Here an experimental and theoretical study of epitaxial (GeTe)m(Sb2Te3)n with GeTe-rich composition is presented. These layered films feature a tunable distribution of (GeTe)m(Sb2Te3)1 blocks of different sizes. Breakthrough evidence of ferroelectric displacement in thick (GeTe)m(Sb2Te3)1 lamellae is provided. The density functional theory calculations suggest the formation of a tilted (GeTe)m slab sandwiched in GeTe-rich blocks. That is, the net ferroelectric polarization is confined almost in-plane, representing an unprecedented case between 2D and bulk ferroelectric materials. The ferroelectric behavior is confirmed by piezoresponse force microscopy and electroresistive measurements. The resilience of the quasi van der Waals character of the films, regardless of their composition, is also demonstrated. Hence, the material developed hereby gathers in a unique 2D platform the phase-change and ferroelectric switching properties, paving the way for the conception of innovative device architectures

DIGISER. Digital Innovation in Governance and Public Service Provision

Digital Innovation Challenges In view of the increasingly intense pressures on the public sector to address the challenges of our time, governments and other public entities are gradually adopting digital innovation, seeking to promote quality public services. Digital technologies and capabilities create opportunities to re-organise public service inno- vation and delivery in ways that reduce cost and increase quality, proactiveness and citizen-centricity. Multilevel governance, networks and other collaboration systems (at local, regional, national and interna- tional level) are gaining importance as key drivers of this process of digital innovation and transformation. The link to the innovation ecosystem, including all sectors of activity, both private and public (e.g., academia, industry, business, citizens and governments) appears as fundamental in all phases of the creation, devel- opment, implementation and maintenance of public services and policy making. Information and communi- cation technologies are conceived as essential elements to support the creation and sustainability of these collaboration processes. In an era in which information gains relevance in the management of the territory and allows new power relations, the expectations of citizens are increasingly demanding and specific. Considering the develop- ments of recent years, such as the economic, social and health crises, the pressure placed on the resolution of global challenges is progressively transferred to the scope of cities. There are several elements that con- tribute to the importance of cities in the digital innovation transformation process namely buying- power, being closer to citizens and being able to work across different sectors. In fact, urban territories increasingly represent a greater number of citizens - in Europe, for example, they correspond to 75% of the population - have greater autonomy in management, worldwide they contribute to 80% of the global GDP and have the potential to provide a major contribution to the resolution of global challenges. The balance between change (promoted by the digital innovation strategies) and stability (driven by organi- sational inertia) needs to be handled carefully. The transformation process has to be based on a long-term strategy and to occur in a sustainable way, by focusing on learning experiences and knowledge and tech- nology transfer, while being sensitive to the local context to ensure improvement. At the European level, the Digital Transition has been considered a main goal for the next decade. The EU launched the European Green Deal and Europe Fit for the Digital Age, a twin initiative, which links green and digital transition. The vision for the EU ́s digital decade is reflected in the Digital Compass 2030 and includes 4 cardinal points: skills, government, infrastructure and Business. With the aim of having 100% of the key public services online by 2030, the digital compass ensures that digital will contribute in a positive way to improve citizens quality of life while reducing the resources spent. To support this vision, and by understanding the importance of community-led data-driven solutions and the potential of collaborative ap- proaches, several initiatives are being implemented. The Living-in.EU movement, for example, points out the European Way’ where multi-level governance and co-creation processes support the development of a cohesive digital Europe in the path towards digital transition. Another initiative contributing to this strategy is promoted by Open & Agile Smart Cities which is connecting cities through Minimal Interoperability Mech- anisms (MIMs) - “a set of practical capabilities based on open technical specifications that allow cities and communities to replicate and scale solutions globally”. The MIMs contribute to the creation of the European Single Market by providing a common technical ground for the procurement and deployment of urban data platforms and end-to-end solutions in cities