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Thanks to its insolubility, mineral dust is considered a stable proxy in polar ice cores. With this study we show that the Talos Dome ice core (TALDICE, Ross Sea sector of East Antarctica) displays evident and progressive signs of post-depositional processes affecting the mineral dust record below 1000g m deep. We apply a suite of established and cutting-edge techniques to investigate the properties of dust in TALDICE, ranging from concentration and grain size to elemental composition and Fe mineralogy. Results show that through acidic/oxidative weathering, the conditions of deep ice at Talos Dome promote the dissolution of specific minerals and the englacial formation of others, affecting primitive dust features. The expulsion of acidic atmospheric species from ice grains and their concentration in localized environments is likely the main process responsible for englacial reactions. Deep ice can be seen as a "geochemical reactor"capable of fostering complex reactions which involve both soluble and insoluble impurities. Fe-bearing minerals can efficiently help in exploring such transformations.

High-entropy oxides based on transition metals, such as Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O (TM-HEO), have recently drawn special attention as potential anodes in lithium-ion batteries due to high specific capacity and cycling reversibility. However, the lithiation/delithiation mechanism of such systems is still controversial and not clearly addressed. Here, we report on an operando XAS investigation into TM-HEO-based anodes for lithium-ion cells during the first lithiation/delithiation cycle. This material showed a high specific capacity exceeding 600 mAh g-1 at 0.1 C and Coulombic efficiency very close to unity. The combination of functional and advanced spectroscopic studies revealed complex charging mechanisms, developing through the reduction of transition-metal (TM) cations, which triggers the conversion reaction below 1.0 V. The conversion is irreversible and incomplete, leading to the final collapse of the HEO rock-salt structure. Other redox processes are therefore discussed and called to account for the observed cycling behavior of the TM-HEO-based anode. Despite the irreversible phenomena, the HEO cubic structure remains intact for ∼60% of lithiation capacity, so proving the beneficial role of the configuration entropy in enhancing the stability of the HEO rock-salt structure during the redox phenomena.

Many interpretations have been proposed to explain the presence of jarosite within Martian surficial sediments, including the possibility that it precipitated within paleo-ice deposits owing to englacial weathering of dust. However, until now a similar geochemical process was not observed on Earth nor in other planetary settings. We report a multi-analytical indication of jarosite formation within deep ice. Below 1000 m depth, jarosite crystals adhering on residual silica-rich particles have been identified in the Talos Dome ice core (East Antarctica) and interpreted as products of weathering involving aeolian dust and acidic atmospheric aerosols. The progressive increase of ice metamorphism and re-crystallization with depth, favours the relocation and concentration of dust and the formation of acidic brines in isolated environments, allowing chemical reactions and mineral neo-formation to occur. This is the first described englacial diagenetic mechanism occurring in deep Antarctic ice and supports the ice-weathering model for jarosite formation on Mars, highlighting the geologic importance of paleo ice-related processes on this planet. Additional implications concern the preservation of dust-related signals in deep ice cores with respect to paleoclimatic reconstructions and the englacial history of meteorites from Antarctic blue ice fields.

Aim of this retrospective, multicenter study was to evaluate early and mid-term clinical and hemodynamic results of patients who underwent surgical aortic valve replacement (SAVR) with Intuity rapid-deployment bioprostheses (RDB) (Edwards Lifesciences, Irvine, CA). We analyzed data from the Italian Registry of Intuity Valve (INTU-ITA registry) that is a national, real-world and independent from the industry registry. Preoperative variables were defined according to EuroSCORE and postoperative outcomes according to Valve Academic Research Consortium (VARC). Survival distribution was evaluated using the Kaplan-Meier approach. A Cox-Proportional Hazard Model was employed to assess the effect of the covariates on patients’ survival. The registry included 1687 patients from 23 centers (June 2012-September 2019). Aortic cross clamp time for isolated SAVR was 55 minutes (IQR: 45–70 minute). Postoperative pace-maker rate was 6.3%. At discharge transaortic peak and mean gradients were: 18 mm Hg (IQR: 14–23 mm Hg) and 10 mmHg (IQR: 8–13 mm Hg), respectively. Indexed effective orifice area was 1.10 cm2/m2 (IQR: 0.91–1.31 cm2/m2) and the incidence of severe patient-prosthesis mismatch was 0.6%. Hemodynamic data for all valve sizes remained stable during follow-up. Thirty-day overall mortality was 1.8% (30 patients), and at follow-up it was 5.3% (89 patients). Kaplan-Meier overall survival was 95.5% (94.3–96.7%); 90.7% (88.3–93.1%); 86.4% (82.6–90.4%) at 1, 3, and 5 years, respectively. Serum creatinine (HR: 1.36; 95%CI: 1.04–1.81; p = 0.0397) and cross-clamp time (HR: 1.01; 95%CI: 1.002–1.017; p = 0.0077) were identified as independent predictors of mortality. According to our data from the INTU-ITA registry, SAVR with RDB provides good early clinical and hemodynamic results that are confirmed at follow-up.

Background: The aim of this multicenter retrospective study was to compare early and midterm clinical and hemodynamic results of aortic valve replacement with rapid-deployment bioprostheses performed through conventional full-sternotomy vs mini-sternotomy. Methods: Data from the Italian multicenter registry of aortic valve replacement with rapid-deployment bioprostheses (INTU-ITA registry) were analyzed. Patients were divided into 2 groups: full sternotomy (FS) and ministernotomy (MS). Primary endpoint was the comparison of early and midterm mortality. Secondary endpoints were: comparison of intraoperative variables, complications, and hemodynamic performance. A propensity score weighting approach was used for data analysis. Results: A total of 1057 patients were analyzed: 435 (41.2%) and 622 (58.8%) in group FS and MS, respectively. Thirty-day mortality was 1.6% and 0.6% in FS and MS groups, respectively (P =.074). cardiopulmonary bypass time was 78.5 minutes and 83 minutes in FS and MS groups, respectively (P =.414). In the overall cohort, the incidence of intraoperative complications and of device success was 3.8% (40 patients) and 95.9% (1014 patients), respectively, with no significant differences between groups. Survival at 1, 3, and 5 years was 94.1%, 98.1%, 88.5% and 91.8%, 85.2%, and 84.8% in FS and MS groups, respectively (P =.412). The 2 groups showed similar postoperative gradients (median mean gradient, FS: 10.0 mm Hg, MS: 11.0 mm Hg; P =.170) and also similar incidence of patient–prosthesis mismatch (FS: 7%, MS: 6.4%, P =.647). Conclusions: According to our data, rapid-deployment bioprostheses allow the performance of minimally invasive aortic valve replacement with similar surgical times and similar clinical and hemodynamic outcomes to conventional surgery and should be considered the first choice in these procedures.

Airborne dust extracted from deep ice core perforations can provide chemical and mineralogical insight into the history of the climate and atmospheric conditions, with unrivalled temporal resolution, time span and richness of information. The availability of material for research and the natural complexity of the particulate, however, pose significant challenges to analytical methods. We present the developments undertaken to optimize the experimental techniques, materials and protocols for synchrotron radiation-based analysis, in particular for the acquisition of combined Synchrotron Radiation X-Ray Fluorescence and X-ray Absorption Spectroscopy data

X-ray absorption near edge structure (XANES) measurements at the Fe K-edge were performed on aeolian dust in the TALos Dome Ice CorE drilling project (TALDICE) ice core drilled in the peripheral East Antarctic plateau, as well as on Southern Hemisphere potential source area samples. While South American sources show, as expected, a progressive increase in Fe oxidation with decreasing latitude, Antarctic sources show Fe oxidation levels higher than expected in such a cold polar environment, probably because of their very high exposure ages. Results from the TALDICE dust samples are compatible with a South American influence at the site during MIS2 (marine isotopic stage 2, the last and coldest phase of the last glacial period), in particular from Patagonia and Tierra del Fuego. However, a contribution from Australia and/or local Antarctic sources cannot be ruled out. Finally, important changes also occurred during the deglaciation and in the Holocene, when the influence of Antarctic local sources seems to have become progressively more important in recent times. This research is the first successful attempt to extract temporal climatic information from X-ray absorption spectroscopic data of the insoluble mineral dust particles contained in an ice core and shows the high potential of this technique

Iron is thought to limit the biomass of phytoplankton populations in extensive regions of the ocean, which are referred to as high-nutrient low-chlorophyll (HNLC) regions. Iron speciation in soils is still poorly understood. We have investigated inorganic and organic standard substances, diluted mixtures of common Fe minerals in insoluble dust in snow from the Laohugou No.12 glacier, and sand (including soil and moraine) samples that were collected from western China. The speciation of iron (Fe) in insoluble dust and sand was determined by X-ray absorption near-edge structure (XANES) spectroscopy. A linear fit combination (LCF) analysis of the experimental spectra compared to a large set of reference compounds showed that all spectra can be fitted by only four species: Fe2O3, Fe3O4, biotite, and ferrous oxalate dihydrate (FOD). A significant altitude effect was detected for snow. The proportion of Fe2O3 in snow decreases gradually, and vice versa for FOD. As for Fe3O4 and biotite, the altitude effect was also detected, but separate regions should be considered to be deduced by topography. The Fe species in moraines and soils were also analyzed to identify the source of moraines and the heterogeneity of soils, and were compared with snow.

In this work, we will report applications of the total external X-ray fluorescence (TXRF) station, a prototype assembled at the XLab Frascati laboratory (XlabF) at the INFN National Laboratories of Frascati (INFN LNF). XlabF has been established as a facility to study, design and develop X-ray optics, in particular, polycapillary lenses, as well as to perform X-ray experiments for both elemental analysis and tomography. The combination of low-power conventional sources and policapillary optics allows assembling a prototype that can provide a quasi-parallel intense beam for detailed X-ray spectroscopic analysis of extremely low concentrated samples, down to ng/g. We present elemental analysis results of elements contained in tree rings and of dust stored in deep ice cores. In addition to performing challenging environmental research studies, other experiments aim to characterize novel optics and to evaluate original experimental schemes for X-ray diffraction (XRD), X-ray fluorescence (XRF and TXRF) and X-ray imaging

The possibility of finding a stratigraphically intact ice sequence with a potential basal age exceeding one million years in Antarctica is giving renewed interest to deep ice coring operations. But the older and deeper the ice, the more impactful are the post-depositional processes that alter and modify the information entrapped within ice layers. Understanding in situ post-depositional processes occurring in the deeper part of ice cores is essential to comprehend how the climatic signals are preserved in deep ice, and consequently how to construct the paleoclimatic records. New techniques and new interpretative tools are required for these purposes. In this respect, the application of synchrotron light to microgram-sized atmospheric dust samples extracted from deep ice cores is extremely promising. We present here preliminary results on two sets of samples retrieved from the Talos Dome Antarctic ice core. A first set is composed by samples from the stratigraphically intact upper part of the core, the second by samples retrieved from the deeper part of the core that is still undated. Two techniques based on synchrotron light allowed us to characterize the dust samples, showing that mineral particles entrapped in the deepest ice layers display altered elemental composition and anomalies concerning iron geochemistry, besides being affected by inter-particle aggregation

Ice cores from inner East Antarctica provided some of the longest and most detailed climatic reconstructions and allowed understanding the relationships between atmospheric mineral dust and climate. In this work we present synchrotron‐radiation XRF geochemical data of dust from the TALDICE ice core drilled at Talos Dome, a peripheral ice dome of East Antarctica (Western Ross Sea). Results highlight a dominant southern South American origin for dust at TALDICE during the Last Glacial Maximum, similarly to other sites located further inland onto the polar plateau. On the contrary a different scenario concerns Talos Dome during the Holocene if it is compared to more inner sites. The tight connection between high southern latitudes and Antarctica that characterizes cold climate stages, becomes weaker since the onset of the last climatic transition and throughout the Holocene. The net effect of this process at Talos Dome is a modification of the atmospheric and environmental settings, owing to local Antarctic sources of Victoria Land to gain importance and become the dominant ones. At the same time in inner East Antarctica the provenance of dust remains remote also during Holocene, revealing an evolution of the homogeneous scenario observed in glacial periods. The enhanced sensitivity of peripheral ice sheet sites to local dust sources makes Talos Dome an ideal site to assess the climatic and atmospheric changes of the peripheral sectors of East Antarctica during the current interglacial period

Previous work has shown that nanocrystalline samples of lithium tantalate and titanate prepared by high-energy milling show unusually high lithium ion conductivity. Here, we report an X-ray absorption spectroscopy (XAS) study at the Ti K-edge and the Ta L3 edge of samples that have been milled for various lengths of time. For both systems the results show that milling creates amorphous material whose quantity increases with the milling time. The more extensive data for the tantalate shows that milling for only 30 minutes generates ~25% amorphous content in the sample. The content rises to ~60% after 16 hours. It is suggested that it is the motion of the lithium ions through the amorphous content that provides the mechanism for the high ionic conductivity.