Definition of a genetic model for the dark-colored overgrowths in pegmatitic gem tourmaline crystals

Elba gem tourmalines are renowned for the delicate pastel colors and the perfection of their crystal shapes in small size. Characteristic for these tourmalines is the presence of color anomalies that occur as dark-colored terminations, frequently at the analogous pole that typically are rich in Fe and/or Mn. The formation of such dark-colored overgrowths is related to sudden physicochemical changes in the crystallization environment during the latest-stages of tourmaline crystal growth. However, the detailed events that led to the availability of Fe and/or Mn in the pocket environment, resulting in the growth of late-stage tourmalines, remained unclear. The goal of this Ph.D project is the definition of a genetic model for the dark-colored overgrowths in pegmatitic gem tourmaline crystals. Since tourmaline is an excellent petrogenetic indicator, the origin and chemical composition of fluids involved in tourmaline crystallization, responsible for such color anomalies, have also been investigated. To achieve this goal, selected gem tourmaline crystals with dark overgrowths of different colors and textural features from several miarolitic Li-bearing aplite-pegmatite veins, located in the eastern border of Monte Capanne monzogranite pluton (Elba Island, Italy), were studied. Chemical and spectroscopic investigations were applied as experimental approach in order to describe the crystal-chemical characteristics of the zones characterized by such color anomalies. This information, along with microstructural and paragenetic observations of the cavities in which the studied tourmaline samples were collected, were used to determine and propose a general genetic model for the color anomalies observed at the termination of Elba gem tourmaline crystals. This study was further extended to tourmaline samples collected from the Alto Ligonha pegmatite district (Nampula Province, NE Mozambique). Gem-quality tourmalines from the Alto Ligonha pegmatite district are among the most renowned for the combination of color and rarity. These features make them unique from a gemological viewpoint and therefore with a high commercial value, limiting the information regarding their crystal-chemical characteristics. To fill this gap, several tourmaline samples from the secondary deposit of Mavuco, in the eastern portion of the Alto Ligonha pegmatite district, were studied. These tourmaline samples were provided by ongoing mining projects, and were subjected to an in-depth analysis. Specifically, a detailed chemical characterization as well as a correlation study between compositional data and color displayed by the tourmaline crystals, were conducted. In addition, on selected samples with particular chromatic features, optical absorption spectroscopy analyses were performed. For all the tourmaline samples analyzed, the gemological variety, according to the color displayed, was identified and the relative color mechanisms were investigated. Tourmaline grains from the secondary deposit of Mavuco are also characterized by a dark-colored prismatic overgrowth. The genetic mechanisms responsible for these prismatic overgrowths have not been defined so far, as the pegmatitic source from which these tourmalines originated was still uncertain. This uncertainty was essentially due to the strong NYF (Niobium-Yttrium-Fluorine) geochemical affinity (Li- and B-poor composition) of the Alto Ligonha pegmatites located quite close the secondary deposit of Mavuco, as well as the rudimentary excavation techniques, which did not allow the exploration of new pegmatitic deposits in the Alto Ligonha district. To gain information about the processes that led to the formation of the prismatic dark-colored overgrowths, selected tourmaline crystals from a recently discovered pegmatitic field, the so-called “Marina” pegmatite (Mavuco area), were analyzed. The “Marina” pegmatite was hypothesized to be a source of the detrital tourmaline grains of the Mavuco area, given its proximity to the secondary deposit, and its LCT geochemical signature. Studies on tourmaline crystals from the “Marina” pegmatite were carried out to confirm the above hypothesis, through the comparison of the compositional data obtained from such tourmaline crystals with those obtained from the detrital tourmalines of the secondary deposit of Mavuco. The same studies allowed obtain detailed information on the genesis of the dark-colored prismatic overgrowths, which also characterize some of the detrital tourmalines. During the chemical characterization activity, two new mineral species of the tourmaline supergroup were discovered. Both of them were approved by the IMA-CNMNC (International Mineralogical Association-Commission on New Minerals, Nomenclature and Classification) and named celleriite, ideally □(Mn2+2Al)Al6(Si6O18)(BO3)3(OH)3(OH), and ferro-bosiite, ideally NaFe3+3(Al4Fe2+2)(Si6O18)(BO3)3(OH)3O. The results obtained in this PhD research improved the knowledge on the opening of geochemical systems in which tourmaline crystallized, and allowed the definition of a genetic model for the formation of the dark-colored overgrowths in tourmaline crystals. This model can be exported to explain late-stage color and composition anomalies of gem tourmaline crystals of many other gem-pegmatite deposits in the world

Mirror imaging of impacted and supernumerary teeth in dizygotic twins: a case report

Background: Mesiodens is the most common type of supernumerary tooth found in the premaxilla. It might be discovered during the clinical examination as a casual finding on a radiograph or as the cause of an unerupted maxillary central incisor. The genetic transmission of supernumerary and impacted teeth is poorly understood. Mirror imaging in twins has been reported frequently in relation to several unilateral dental anomalies including mesiodens. This phenomenon is the appearance of an asymmetrical feature or anomaly occurring on the right side of one twin but on the left side of the other twin. The event of mesiodens mirror imaging in monozygotic twins has been described in literature. Results: This is the first reported case of mesiodens mirror imaging in dizygotic twins. The described mesiodens caused the eruption failure of maxillary permanent incisors. The supernumerary teeth were removed to facilitate the spontaneous eruption of the impacted permanent maxillary incisors. Clinical Implications: Studies related to supernumerary teeth can be useful to clinicians in the early diagnosis of this anomaly. Clinical and radiographic examinations provide a correct therapeutic approach

Chromium-rich vanadio-oxy-dravite from the Tzarevskoye uranium–vanadium deposit, Karelia, Russia. A second world-occurrence of Al–Cr–V–oxy-tourmaline

A green tourmaline sample from the Tzarevskoye uranium–vanadium deposit, close to the Srednyaya Padma deposit, Lake Onega, Karelia Republic, Russia, has been found to be the second world-occurrence of Cr-rich vanadio-oxy-dravite in addition to the Pereval marble quarry, Sludyanka crystalline complex, Lake Baikal, Russia, type-locality. From the crystal-structure refinement and chemical analysis, the following empirical formula is proposed: X(Na0.96K0.02□0.02)Σ1.00 Y(V1.34Al0.68Mg0.93Cu2+0.02Zn0.01Ti0.01)Σ3.00 Z(Al3.19Cr1.36V0.03Mg1.42)Σ6.00(TSi6O18)(BBO3)3V(OH)3W[O0.60(OH)0.23F0.17]Σ1.00. Together with the data from the literature, a compositional overview of Al–V–Cr–Fe3+-tourmalines is provided by using [6]Al–V–Cr–Fe3+ diagrams for tourmaline classification. These diagrams further simplify the tourmaline nomenclature as they merge the chemical information over the octahedrally-coordinated sites (Y and Z) by removing the issues of uncertainty associated with cation order–disorder across Y and Z. Results show the direct identification of tourmalines by using the chemical data alone

Blue-growth zones caused by Fe2+ in tourmaline crystals from the San Piero in Campo gem-bearing pegmatites, Elba Island, Italy

Two tourmaline crystals with a blue growth zone at the analogous pole, respectively from the San Silvestro and the Fucili pegmatites, located in the San Piero in Campo village, Elba Island (Tyrrhenian Sea, Italy), have been described for the first time using compositional and spectroscopic data to define their crystal-chemical aspects and the causes of the colour. Compositional data obtained by electron microprobe analysis indicate that both tourmalines belong to the elbaite–fluor-elbaite series. The upper part of each crystal is characterised by an increased amount of Fe (FeO up to ~1 wt.%) and a Ti content below the detection limit. Optical absorption spectra recorded on the blue zone of both samples show absorption bands caused by spin-allowed d-d transitions in [6]-coordinated Fe2+, and no intervalence charge transfer Fe2+-Ti interactions, indicating that Fe2+ is the only chromophore. Mössbauer analysis of the blue zone of the Fucili sample confirmed the Fe2+ oxidation state, implying that the redox conditions in the crystallisation environment were relatively reducing. The presence of colour changes at the analogous termination during tourmaline crystal growth suggests a change in the composition of the crystallisation environment, probably associated with a partial opening of the system

Detection of GAD65 Autoreactive T-Cells by HLA Class I Tetramers in Type 1 Diabetic Patients

Type 1 diabetes (T1D) is an autoimmune disease, in which pancreatic β cells are destroyed in genetically predisposed individuals. While the direct contribution of autoantibodies to the disease pathogenesis is controversial, it is generally recognised that the mechanism of β cell destruction is mediated by autoreactive T cells that had escaped the thymic selection. We aimed to design a method to detect circulating CD8+ T cells autoreactive against an epitope of the glutamic acid decarboxylase autoantigen, isoform 65 (GAD65) ex vivo in T1D patients by using HLA class I tetramers. Low frequencies of GAD65 peptide-specific CD8+ cytotoxic T lymphocytes were detected in peripheral blood lymphocytes (PBMC) of normal controls after GAD65 peptide-specific stimulation. Conversely, their frequencies were significantly higher than in controls in PBMC of T1D patients after GAD65 peptide stimulation. These preliminary data are encouraging in order to develop a reliable assay to be employed in large-scale screening studies

Oxygen investigation in the Galileian satellites using AFOSC

Spectroscopy in the visible range of the Galilean satellites is a suitable way to investigate the surface properties of these objects. In recent years, several species, like O_2, O_3, and SO_2, have been detected on the surfaces of these satellites, which were thought to be completely covered only by water ice. The recent detection of the O_2 absorption bands in the Ganymede trailing face \citep{spencer_1995} led to laboratory experiments in order to better constraint the O_2 phases trapped in the water ice surface \citep{vidal_1997}. The same features were observed also on Europa and Callisto surfaces \citep{spencer_2002}, although a better investigation of their properties and their variability with time is still not fully addressed. We proposed ground-based observations with the AFOSC instrument on the 1.8-m telescope in Asiago, to investigate the Galilean satellites? surface properties, focusing both on the leading and trailing faces of the satellites. We used the Volume Phase Holographic grism covering the spectral range 400-1000 nm, with a spectral resolution of about 5000. In this work, we show results of the observations acquired in November 2014, focusing on the leading faces of the satellites. Data were treated using standard methods of data reduction. Further observations with the same setup, scheduled for February 2015 to observe the trailing face of the Galileian satellites, will complement the program. These observations are in preparation to the future science we will be able to perform with the MAJIS spectrometer on the European JUICE mission

Dynamics investigation in the Venus upper atmosphere

The O_2 nightglow emissions in the infrared spectral range are important features to investigate dynamics at the mesospheric altitudes, in the planetary atmosphere. In this work, we analyzed the profiles obtained at limb by the VIRTIS spectrometer on board the Venus Express mission, acquired during the mission period from 2006-07-05 to 2008-08-15 to investigate possible gravity waves characteristics at the airglow altitudes. Indeed, several profiles present double peaked structures that can be interpreted as due to gravity waves. In analogy to the Earth's and Mars cases, we use a well-known theory to model the O_2 nightglow emissions affected by gravity waves propagation, in order to support this thesis and derive the waves properties. We discuss results from 30 profiles showing double peaked structures, focusing on vertical wavelength and wave amplitude of the possible gravity waves. On average, the double peaked profiles are compatible with the effects of gravity waves with a vertical wavelength ranging between 7 and 16 km, and wave amplitude of 3-14%. A comparison with gravity waves properties in the Mars and Earth's atmospheres, using the same theory, is also proposed \citep{altieri_2014}. \ The research is supported by ASI (contract ASI-INAF I/050/10/0)

JUNO/JIRAM's view of Jupiter's H3+ emissions

The instrument JIRAM (Jovian Infrared Auroral Mapper), on board the NASA spacecraft Juno, is both an imager and a spectrometer. Two distinct detectors are used for imaging and spectroscopy. The imager acquires Jupiter images in two bands, one of which (L band, 3.3-3.6 μm) is devoted to monitor the H+3 emission. The spectrometer covers the spectral region from 2 to 5 μm (average spectral resolution 9 nm) with a 256 pixels slit, that can observe the same scene of the L band imager with some delay. JIRAM scientific goals are the exploration of the Jovian aurorae and the planet’s atmospheric structure, dynamics and composition. Starting early July 2016 Juno is orbiting around Jupiter. Since then, JIRAM has provided an unprecedented amount of measurements, monitoring both Jupiter’s atmosphere and aurorae. In particular the camera has monitored Jupiter’s poles with unprecedented spatial resolution, providing new insights in both its aurorae and the polar dynamic. The main findings obtained by the L imager are detailed pictures of Jupiter’s aurorae showing an extremely complex morphology of the H+3 distribution in the main oval and in the moon’s footprints. The spectrometer has enabled to measure the distribution of both H+3 concentration and temperature. The analysis of the north auroral region limb observations shows that the peak density of H+3 is above 750 km and that often it is anticorrelated to the temperature, confirming the infrared cooling effect of H+

Longitudinal study on low-dose aspirin versus placebo administration in silent brain infarcts: the silence study

Background. We investigated low-dose aspirin (ASA) efficacy and safety in subjects with silent brain infarcts (SBIs) in preventing new cerebrovascular (CVD) events as well as cognitive impairment. Methods. We included subjects aged ≥45 years, with at least one SBI and no previous CVD. Subjects were followed up to 4 years assessing CVD and SBI incidence as primary endpoint and as secondary endpoints: (a) cardiovascular and adverse events and (b) cognitive impairment. Results. Thirty-six subjects received ASA while 47 were untreated. Primary endpoint occurred in 9 controls (19.1%) versus 2 (5.6%) in the ASA group (p=0.10). Secondary endpoints did not differ in the two groups. Only baseline leukoaraiosis predicts primary [OR 5.4 (95%CI 1.3-22.9, p=0.022)] and secondary endpoint-A [3.2 (95%CI 1.1-9.6, p=0.040)] occurrence. Conclusions. These data show an increase of new CVD events in the untreated group. Despite the study limitations, SBI seems to be a negative prognostic factor and ASA preventive treatment might improve SBI prognosis. EU Clinical trial is registered with EudraCT Number: 2005-000996-16; Sponsor Protocol Number: 694/30.06.04

Body mass index rather than the phenotype impacts precocious ultrasound cardiovascular risk markers in polycystic ovary syndrome

Objective Research into cardiovascular disease (CV) prevention has demonstrated a variety of ultrasound (US) markers predicting risk in the general population but which have been scarcely used for polycystic ovary syndrome (PCOS). Obesity is a major factor contributing to CV disease in the general population, and it is highly prevalent in PCOS. However, it is still unclear how much risk is attributable to hyperandrogenism. This study evaluates the most promising US CV risk markers in PCOS and compares them between different PCOS phenotypes and BMI values. Design Women fulfilling the Rotterdam criteria for PCOS were recruited from our outpatient clinic for this cross-sectional study. Methods Participants (n\u2009=\u2009102) aged 38.9 \ub1 7.4 years were stratified into the four PCOS phenotypes and the three BMI classes (normal-weight, overweight, obese). They were assessed for clinical and biochemical parameters together with the following US markers: coronary intima-media thickness (cIMT), flow-mediated vascular dilation (FMD), nitroglycerine-induced dilation (NTG), and epicardial fat thickness (EFT). Results There was no statistical difference among the four phenotypes in terms of cIMT, FMD, NTG or EFT, however all the US parameters except NTG showed significant differences among the three BMI classes. Adjusting for confounding factors in multiple regression analyses, EFT retained the greatest direct correlation with BMI and cIMT remained directly correlated but to a lesser degree. Conclusions This study showed that obesity rather than the hyperandrogenic phenotype negatively impacts precocious US CV risk markers in PCOS. In addition, EFT showed the strongest association with BMI, highlighting its potential for estimating CV risk in PCOS