Structural and Thermodynamic Properties of Transition Metal Ions in Room Temperature Ionic Liquids

openRoom temperature ionic liquids (RTILs) are salts made by an organic cation and an organic or inorganic anion, which are at the liquid state at 25 °C. RTILs have attracted much attention as new sustainable solvents owing to some unique properties they usually possess, such as a practically negligible vapor pressure, non-flammability, high thermal stability, wide electrochemical windows, good solvation ability and supposed low toxicity. These features make RTILs good candidates for the substitution of classical organic solvents in many technological applications. For these reasons, they are currently studied as new media for chemical separations, electrodepositions, electrolytes for batteries and supercapacitors, catalysis and pharmaceutical research. Several of these applications also involve the presence of metal ions as solvated species in RTILs. In this field, structural and thermodynamic data about single-ion solvation are fundamental quantities that need to be known to improve new technologies. However, this fundamental knowledge still lacks for many metal species in several ionic liquids. The aim of this thesis is to obtain a complete description of metal ions solvation in RTILs both from a structural and thermodynamic point of view. Molecular dynamics (MD) simulations and X-ray absorption spectroscopy (XAS) experiments have been performed to study solutions of metal ions of industrial, environmental and economic interest such as Zn2+, Co2+, Ag+ in widely used RTILs like those based on the [Tf2N]- (bis(trifluoromethylsulfonyl)imide) and [BF4]- (tetrafluoroborate) anions within the [Cnmim]+ (1-alkyl-3-methylimidazolium) cation. MD simulations have been carried out on Zn2+ in [Cnmim][Tf2N] (n = 2, 4) and [C4mim][BF4]. The obtained thermodynamic data are in good agreement with literature experimental values and indicate the goodness of the employed protocol. The calculated Gibbs free energies of transfer (ΔGtrans) from water to the [Cnmim][Tf2N] RTILs suggest that Zn2+ is more favorably solvated in aqueous solution than in this class of ionic liquids, while the opposite is found for [C4mim][BF4]. The obtained single-ion solvation enthalpies and entropies provided an interpretation of the different contributions to the calculated free energies. In addition, XAS experimental results allowed to understand the coordination of Zn2+ in water-saturated [C4mim][Tf2N], representing the real-operating condition in a liquid-liquid extraction. A similar picture has been obtained for Co2+ in [C4mim][Tf2N]. MD calculated ΔGtrans showed that the metal ion is still more favorably solvated in water than in the RTIL because of an unfavorable entropic contribution. XAS experiments and data-fitting allowed to obtain Co2+ coordination in dry [C4mim][Tf2N]. The metal resulted to be bound by six monodentate anions forming the [Co(Tf2N)6]4- octahedral species. In addition, water is found to preferentially coordinate the metal when present at high concentrations in the RTIL, as provided by UV-Vis data. As regards the study about Ag+ in RTILs, a totally different picture with respect to Zn2+ and Co2+ has been obtained. MD results showed that this ion is more favorably solvated both in [C4mim][Tf2N] and [C4mim][BF4] with respect to water, and this encourages the employment of these RTILs as extracting phase for this metal. Ag+ resulted coordinated by four or five RTILs anions, depending on the employed interaction potential. However, when considering the transfer of Ag+ from water to the RTILs, great care must be taken because of a possible change in the coordination number. Indeed, preliminary XAS data suggest a linear coordination for this metal ion in aqueous solution, differently from the tetrahedral model that is usually accepted and reproduced by the current classical potentials. Ab initio MD simulations with the Car-Parrinello method seemed to confirm this observation.Dottorato di ricerca in Scienze dell'ingegneria energetica e ambientaleopenBusato, Matte

Caught while Dissolving: Revealing the Interfacial Solvation of the Mg2+ Ions on the MgO Surface

Interfaces between water and materials are ubiquitous and are crucial in materials sciences and in biology, where investigating the interaction of water with the surface under ambient conditions is key to shedding light on the main processes occurring at the interface. Magnesium oxide is a popular model system to study the metal oxide-water interface, where, for sufficient water loadings, theoretical models have suggested that reconstructed surfaces involving hydrated Mg2+ metal ions may be energetically favored. In this work, by combining experimental and theoretical surface-selective ambient pressure X-ray absorption spectroscopy with multivariate curve resolution and molecular dynamics, we evidence in real time the occurrence of Mg2+ solvation at the interphase between MgO and solvating media such as water and methanol (MeOH). Further, we show that the Mg2+ surface ions undergo a reversible solvation process, we prove the dissolution/redeposition of the Mg2+ ions belonging to the MgO surface, and we demonstrate the formation of octahedral [Mg(H2O)6]2+ and [Mg(MeOH)6]2+ intermediate solvated species. The unique surface, electronic, and structural sensitivity of the developed technique may be beneficial to access often elusive properties of low-Z metal ion intermediates involved in interfacial processes of chemical and biological interest

The Complex Story Behind a Deep Eutectic Solvent Formation as Revealed by L‑Menthol Mixtures with Butylated Hydroxytoluene Derivatives.

An in-depth study of the hydrophobic eutectic mixtures formed by L-menthol (MEN) with the butylated hydroxytoluene (BHT), 2-tert-butyl-pcresol (TBC), and p-cresol (PC) compounds has been carried out, where TBC and PC are analogous to the BHT species but with a different degree of steric hindrance around the hydroxyl group. Thermal characterization evidenced that the BHT/MEN system can be classified as an ideal eutectic, while the TBC/MEN and PC/MEN mixtures behave as type V deep eutectic solvents (DESs) for a wide range of compositions around the eutectic point. As shown by an array of experimental and theoretical methods, in the BHT/MEN mixtures the establishment of hydrogen-bond (H-bond) interactions between the components is dramatically hampered because of the steric hindrance in the BHT molecule, so that the achievement of a liquid phase at room temperature for the eutectic composition is driven by apolar−apolar attractions among the alkyl functional groups of the constituents. Differently, the TBC-MEN donor−receptor H-bond is the main driving force for the formation of a type V DES and derives from a concurrence of electronic and steric factors characterizing the TBC molecule. Finally, the absence of steric hindrance around the hydroxyl group allows the self-association among PC molecules through H-bonded networks already in the pristine compound, but the replacement with the more favorable PC-MEN H-bond provides a type V DES upon mixing of these components. Our combined approach, together with the peculiarity of the inspected systems, delivered an archetypal study able to shed light onto the various contributions ruling the structure− properties relationship in DESs and possibly deepening the currently accepted view of these inherently complex media

Para -Aminosalicylic acid in the treatment of manganese toxicity. Complexation of Mn2+ with 4-amino-2-hydroxybenzoic acid and its N -acetylated metabolite

Manganese excess can induce in humans a neurological disorder known as manganism. A possible remedy should be chelation therapy, even though a chelation schedule for manganism has not been currently established. para-Aminosalicylic acid (PAS) has demonstrated effectiveness in reducing manganism symptoms. In this work, a study of the protonation equilibria of para-aminosalicylic acid and of its N-acetylated metabolite (Ac-PAS) and of their complexation reactions with Mn2+ is presented, and also extended to the main essential metal ions Cu2+ and Fe3+. A number of complementary techniques (potentiometry, spectrophotometry, fluorimetry, EPR) have been used for a thorough comprehension of the protonation and complex formation equilibria, with the addition of DFT calculations, which provide insights into the relative stabilities and electronic properties of the formed species. Both PAS and Ac-PAS form 1 : 1 and 1 : 2 metal : ligand complexes with the target Mn2+ ion; surprisingly the N-acetylated metabolite forms stronger complexes, whose implications in chelation therapy have been pointed out by a speciation study. It is presumed that the relatively small metabolite can penetrate across the blood-brain-barrier and exert its Mn-mobilizing action intracellularly in vulnerable neurons

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction

Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of √s=7 TeV proton-proton collisions

Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb−1 of pp collision data at s√=7TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from ≥6 to ≥9 jets. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a MSUGRA/CMSSM supersymmetric model, where, for large universal scalar mass m 0, gluino masses smaller than 840 GeV are excluded at the 95% confidence level, extending previously published limits. Within a simplified model containing only a gluino octet and a neutralino, gluino masses smaller than 870 GeV are similarly excluded for neutralino masses below 100 GeV

Characteristics and patterns of care of endometrial cancer before and during COVID-19 pandemic

Objective: Coronavirus disease 2019 (COVID-19) outbreak has correlated with the disruption of screening activities and diagnostic assessments. Endometrial cancer (EC) is one of the most common gynecological malignancies and it is often detected at an early stage, because it frequently produces symptoms. Here, we aim to investigate the impact of COVID-19 outbreak on patterns of presentation and treatment of EC patients. Methods: This is a retrospective study involving 54 centers in Italy. We evaluated patterns of presentation and treatment of EC patients before (period 1: March 1, 2019 to February 29, 2020) and during (period 2: April 1, 2020 to March 31, 2021) the COVID-19 outbreak. Results: Medical records of 5,164 EC patients have been retrieved: 2,718 and 2,446 women treated in period 1 and period 2, respectively. Surgery was the mainstay of treatment in both periods (p=0.356). Nodal assessment was omitted in 689 (27.3%) and 484 (21.2%) patients treated in period 1 and 2, respectively (p<0.001). While, the prevalence of patients undergoing sentinel node mapping (with or without backup lymphadenectomy) has increased during the COVID-19 pandemic (46.7% in period 1 vs. 52.8% in period 2; p<0.001). Overall, 1,280 (50.4%) and 1,021 (44.7%) patients had no adjuvant therapy in period 1 and 2, respectively (p<0.001). Adjuvant therapy use has increased during COVID-19 pandemic (p<0.001). Conclusion: Our data suggest that the COVID-19 pandemic had a significant impact on the characteristics and patterns of care of EC patients. These findings highlight the need to implement healthcare services during the pandemic

Search for anomalous production of prompt like-sign muon pairs and constraints on physics beyond the standard model with the ATLAS detector

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMAn inclusive search for anomalous production of two prompt, isolated muons with the same electric charge is presented. The search is performed in a data sample corresponding to 1.6 fb-1 of integrated luminosity collected in 2011 at √s = 7 TeV with the ATLAS detector at the LHC. Muon pairs are selected by requiring two isolated muons of the same electric charge with pT > 20 GeV and |η| < 2.5. Minimal requirements are placed on the rest of the event activity. The distribution of the invariant mass of the muon pair m(μμ) is found to agree well with the background expectation. Upper limits on the cross section for anomalous production of two muons with the same electric charge are placed as a function of m(μμ) within a fiducial region defined by the event selection. The fiducial cross-section limit constrains the like-sign top-quark pair-production cross section to be below 3.7 pb at 95% confidence level. The data are also analyzed to search for a narrow like-sign dimuon resonance as predicted for e.g. doubly charged Higgs bosons (H±±). Assuming pair production of H±± bosons and a branching ratio to muons of 100% (33%), this analysis excludes masses below 355 (244) GeV and 251 (209) GeV for H±± bosons coupling to left-handed and right-handed fermions, respectivelyWe acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF, DNSRC and Lundbeck Foundation, Denmark; ARTEMIS, European Union; IN2P3-CNRS, CEA-DSM/IRFU, France; GNAS, Georgia; BMBF, DFG, HGF, MPG and AvH Foundation, Germany; GSRT, Greece; ISF, MINERVA, GIF, DIP and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; FOM and NWO, Netherlands; RCN, Norway; MNiSW, Poland; GRICES and FCT, Portugal; MERYS (MECTS), Romania; MES of Russia and ROSATOM, Russian Federation; JINR; MSTD, Serbia; MSSR, Slovakia; ARRS and MVZT, Slovenia; DST/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SER, SNSF and Cantons of Bern and Geneva, Switzerland; NSC, Taiwan; TAEK, Turkey; STFC, the Royal Society and Leverhulme Trust, United Kingdom; DOE and NSF, United States of America. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular, from CERN and the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFNCNAF (Italy), NL-T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK) and BNL (USA) and in the Tier-2 facilities worldwid