Incorporation of tetrahedral ferric iron in hydrous ringwoodite

Hydrous Fo_{91} ringwoodite crystals were synthesized at 20 GPa and high-temperature conditions using a multi-anvil press. Recovered crystals were analyzed using electron microprobe analysis, Raman spectroscopy, infrared spectroscopy, synchrotron Mössbauer spectroscopy, single-crystal X-ray diffraction, and single-crystal Laue neutron diffraction, to carefully characterize the chemistry and crystallography of the samples. Analysis of the combined data sets provides evidence for the presence of tetrahedrally coordinated ferric iron and multiple hydrogen incorporation mechanisms within these blue-colored iron-bearing ringwoodite crystals. Tetrahedral ferric iron is coupled with cation disorder of silicon onto the octahedrally coordinated site. Cation disorder in mantle ringwoodite minerals may be promoted in the presence of water, which could have implications for current models of seismic velocities within the transition zone. Additionally, the presence of tetrahedrally coordinated ferric iron may cause the blue color of many ringwoodite and other high-pressure crystals

First in-situ measurements of Fe3+/Fetot for oxides and silicates included in natural diamonds with Synchrotron M\uf6ssbauer Source

Diamond is the paramount phase to understand the evolution and the physico- chemical condition of the deep portions of the Earth\u2019s mantle, mainly because: (i) it is the stable phase through which carbon is stored in the deep mantle for long geologic time; (ii) it does contain and preserve different types of inclusions (fluid, mineral, etc.); (iii) it is the only material sampling the mantle to depths of 800 km (e.g. Harte, 2010), although the majority of the mined diamonds worldwide derive from shallower depth (150 to 250 km). The study of mineral inclusions trapped in diamonds allows the retrieval of different pieces of information about the Earth\u2019s interior and its active geodynamics, providing important clues on the initiation of subduction processes (Shirey & Richardson, 2011; Smart et al., 2016), tracking the transfer of material through the mantle transition zone (Stachel et al., 2005; Walter et al., 2011), recording the timing of ingress of fluids to the continental lithosphere (e.g. Shirey et al., 2004), preserving carbonatitic fluid that trigger deep mantle melting (e.g. Schrauder & Navon, 1994; Kopylova et al., 2010), providing samples of primordial noble gases (e.g. Ozima & Igarashi, 2000), and capturing the redox state of the mantle (e.g. Rohrbach & Schmidt, 2011). Unfortunately the majority of the techniques used so far to study the mineral inclusions are destructive. It is only in the last decade that the studies on inclusions in diamond have started to use non-destructive techniques, providing new information which would otherwise be lost using earlier destructive techniques. Such an example is the rim fluids around inclusions in diamonds. In this study we present details of the experimental setup on the determination of Fe3+/Fetot ratios of mineral inclusions whilst still within the diamonds by a non-destructive approach using the Synchrotron M\uf6ssbauer Source (SMS; Potapkin et al., 2012) at the Nuclear Resonance beamline SOURCE ID18 (R\ufcffer & Chumakov, 1996), European Synchrotron Radiation Facility (ESRF), Grenoble. The extremely small X-ray spot size (10 7 15 \u3bcm2) is perfectly suited for our purposes as some inclusions are smaller than 30-50 \u3bcm and the Fe3+/Fetot variation over the same inclusion cannot be performed by using standard laboratory radioactive sources because of the larger beam size. The average collection time for thicker inclusions (~ 200 \u3bcm) was 2 hours per spectrum, whilst the smallest inclusion (~ 30 730 730 \u3bcm3) required a collection time of approximately 10-12 hours in order to get a spectrum with nicely distinguishable features and a high signal-to-noise ratio. In general, application to a suite of silicate and oxide inclusions in diamonds produced comparable results with respect to those obtained using conventional M\uf6ssbauer sources (e.g. McCammon et al., 2004)

Beltrandoite, a new root-name in the högbomite supergroup: the Mg end-member magnesiobeltrandoite-2N3S

Magnesiobeltrandoite-2N3S, ideally Mg6Al20Fe3+2 O38(OH)2, is a new member of the h\uf6gbomite supergroup of minerals. It occurs in magnesian chloritites of a metamorphosed layered mafic complex in the Etirol-Levaz continental slice, middle Valtournenche, Aosta Valley, Italy. Magnesiobeltrandoite-2N3S grows in a fine-grained chlorite matrix associated as inclusions to relict pre-Alpine hercynite spinels and dolomite in cm- to dm-long darker boudins, which are cut by corundum\ufeclinochlore \ub1 dolomite veins. It occurs as subhedral to euhedral black crystals ( 3c50\u2013400mm), dark reddish-brown in thin section. It shows dark brown streak and vitreous lustre. It is brittle, with no cleavage observed and uneven fracture. Mohs hardness 486\u20136\ubd. Dcalc = 3.93 g \ub7 cm3. It shows no fluorescence under UV radiation and no cathodoluminescence. The mineral is optically uniaxial (\u2013) with an estimated mean refractive index of ca. 1.80. Pleochroism is weak with e = deep reddish brown (along c axis) and v = reddish brown ( a5 c). Absorption is E > O. The Raman spectrum shows a weak and strongly polarized broad OH-characteristic absorption centred at 3364 cm1. Electron microprobe analysis combined with Synchrotron M\uf6ssbauer source spectrometry yielded the following empirical formula based on 40 anions per formula unit (pfu) [Al18.36Mg3.96Fe2+2:52Fe3+2:08Ti0.56Cr0.40Zn0.06V3+0.03Mn0.02]S28O38(OH)2. The ideal formula is Mg6Al20Fe3+2O38(OH)2.The eight strongest lines in the X-ray powder diffraction pattern are [dobs/A (I) (h k l)]: 2.858 (42) (1 1 0), 2.735 (51) (1 0 7), 2.484 (46) (0 1 8), 2.427 (100) (1 1 5), 1.568 (29) (1 2 8), 1.514 (30) (0 2 12), 1.438 (42) (2 0 13), and 1.429 (72) (2 2 0). The crystal structure of magnesiobeltrandoite-2N3S [P3m1, a = 5.7226(3), c = 23.0231(9)A, V = 652.95(5)A 3] was refined from X-ray single-crystal data to R1 = 0.022; it is isostructural with magnesioh\uf6gbomite-2N3S

Synchrotron M\uf6ssbauer Source technique for in situ measurement of iron-bearing inclusions in natural diamonds

Natural diamonds containing silicate, oxide and sulfide inclusions are a popular focus of investigation as they uniquely provide a window into the conditions of the Earth\u2019s interior at extreme depths. Recent discoveries based on investigations of deep diamonds have considerably improved our knowledge of the Earth\u2019s deep carbon and water cycles and the oxygen fugacity of the Earth\u2019s interior. Super deep diamonds are those that are believed to have formed at depths of at least 300 km and some evidence suggests depths of at least 800 km. A common inclu- sion in these diamonds is ferropericlase, (Mg,Fe2+)O. Ferropericlase is the second most abundant mineral in the lower mantle, constituting up to about 20 mol% of its volume. The Fe3+/Fetot of ferropericlase is a strong func- tion of oxygen fugacity, and provides a measure of the most recent redox conditions under which it equilibrated. Conventional M\uf6ssbauer spectroscopy using a 57Co point source has been used in the past decades to study the Fe3+/Fetot content in inclusions still trapped in their diamond\u2019s host, however its limitations are the low spatial resolution (not below 3c100 \u3bcm2) and the long acquisition time. The Flank method was also proposed, it is fast, it has high spatial resolution (down to 3c20 \u3bcm2) but it measures the bulk value of Fe3+/Fetot since it cannot distinguish between different phases. An ideal method to measure Fe3+/Fetot values of ferropericlase would com- bine (1) the advantage of M\uf6ssbauer spectroscopy to distinguish Fe3+ in different phases and measure inclusions while still in the diamond, with (2) the advantage of the Flank method to conduct rapid measurements with high spatial resolution. The only method that offers the possibility to satisfy all these requirements is the Synchrotron M\uf6ssbauer Source (SMS). We used the SMS for the first time, to study the iron content and iron distribution in ferropericlase inclusion still contained within its diamond host from Juina (Brazil). This definitive non-destructive technique with extremely high spatial resolution ( 3c15 \u3bcm2) enabled measurements in multiple regions of the 150 7 150 \u3bcm2 inclusion to be sampled and showed that while Fe3+/Fetot values in ferropericlase were below the detection limit (0.02) overall, there was a magnetic component whose abundance varied systematically across the inclusion. Hyperfine parameters of the magnetic component are consistent with magnesioferrite, and the absence of superparamagnetism allows the minimum particle size to be estimated as 3c30 nm. Bulk Fe3+/Fetot values are similar to those reported for other ferropericlase inclusions from Juina. Their variation across the inclusion can provide constraints on its history, and ultimate on the deep carbon processes behind diamonds formation and their exhumation from the transition zone and shallow lower mantle regions

Rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART): study protocol for a randomized controlled trial

BACKGROUND: Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). METHODS/DESIGN: ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH2O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure 6430 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. DISCUSSION: If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this will represent a notable advance to the care of ARDS patients. Conversely, if the ART strategy is similar or inferior to the current evidence-based strategy (ARDSNet), this should also change current practice as many institutions routinely employ recruitment maneuvers and set PEEP levels according to some titration metho

Rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART): Study protocol for a randomized controlled trial

Background: Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). Methods/Design: ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH(2)O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure <= 30 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. Discussion: If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this will represent a notable advance to the care of ARDS patients. Conversely, if the ART strategy is similar or inferior to the current evidence-based strategy (ARDSNet), this should also change current practice as many institutions routinely employ recruitment maneuvers and set PEEP levels according to some titration method.Hospital do Coracao (HCor) as part of the Program 'Hospitais de Excelencia a Servico do SUS (PROADI-SUS)'Brazilian Ministry of Healt

Biopsies de la prostate en 2015: quelle biopsie pour quel patient [Prostate biopsy: which strategy for which patient?].

L'adoption de l'IRM dans le parcours diagnostique a déterminé la transition des biopsies aléatoires aux biopsies ciblées vers les lésions visibles à l'imagerie. L'utilisation de logiciels rendant possible la fusion d'images IRM et échographiques permet d'améliorer significativement la précision diagnostique de ces biopsies. De plus, pour déterminer l'éligibilité d'un patient à une thérapie focale, davantage de précision diagnostique est requise au niveau de toute la glande ; par conséquent, des biopsies avec une densité d'échantillonnage plus élevée par voie transpérinéale peuvent être proposées.Les nouvelles techniques de biopsie de la prostate permettent une prise en charge personnalisée grâce à une meilleure caractérisation de l'agressivité et de l'extension locale du cancer de la prostate. The adoption of multiparametric MRI within the diagnostic pathway has allowed urologists to move from random biopsy to targeted biopsy directed towards MR-visible lesions. The use of software for MR to TRUS fusion may enhance the diagnostic accuracy of targeted biopsy. To determine the eligibility for tissue-preserving approaches, further precision is required, and template prostate mapping biopsy may be offered. The employment of novel biopsy techniques provide better characterisation of the disease, and allows a tailored approach to a single subject