457 research outputs found

    Exotic accessory minerals in layered chromities of the Campo Formoso complex (Brazil)

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    The Campo Formoso stratiform intrusive complex, in Bahia State, Brazil, considered to be of Paleoproterozoic age, consists of a tabular body of ultramafic rocks about 40 km long and 100-1100 m wide. Thick horizons of chromitite are exploited and the deposits are the richest in Brazil. The complex was intruded by the Campo Formoso calc-alkaline batholith, emplaced by the result of the Transamazonian collision-related orogeny. The peridotite was firstly thoroughly serpentinized, then affected by a renewed cycle of hydrothermal alteration as the batholith cooled, leading in the roof zone to emerald mineralization around roof pendants. An even later influx of fluid led to the formation of talc, silica and carbonates, such that the ultramafic rocks were locally converted to listwanite. The chromitite sequences are highly unusual in containing rather exotic minerals, such as monazite-(La), monazite-(Ce), apatite, galena, bismuthinite, antimony, and three unknown minerals of stoichiometry PbSb2, Pb6Sb and PbSb4, all associated with the clinochlore. The latter phases may have formed during hydrothermal activity in the system Pb-Sb. The presence of these exotic minerals in chromitite, which makes this occurrence unique in the world, strongly support the hypothesis that the La, Ce, P, Pb, Bi and Sb were metasomatically added to the Campo Formoso chromitite horizons by hydrothermal fluids emanating from the nearby Campo Formoso calc-alkaline batholith as it cooled

    The Stillwater Complex chromitites : the response of chromite crystal chemistry to magma injection

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    Nineteen chromite crystals from the A, B, E, G, H, J and K chromitite layers of the Peridotite Zone of the Stillwater Complex (Montana, USA) have been studied by means of X-ray single crystal diffraction and microprobe analyses. The results show that samples from the basal A layer are quite different from the others showing very high oxygen positional parameter u (0.2633-0.2635) and Ti- contents (0.059-0.067apfu). Mg# values are within the range 0.21-0.23 while for the other chromites it is in the range 0.45-0.47. Moreover, for the other samples, according to the structural parameters, two groups have been identified. The first one comprises samples of layers B, E and G, the second includes H, J and K layer samples. It is supposed that high Fe2+ and Ti contents of A layer samples are due to the post-crystallization reaction with interstitial liquid. This fact allowed a very slow cooling rate as evidenced by the high u values. The fractionation of evolved magma from within the intrusion and pulse of a new magma bringing more chromium into the chamber lead to Cr- and Fe3+ -rich compositions and consequently to the increase of the cell edges. The decrease of u values seems to be related to the Cr+Fe3+ and/or Al contents

    The podiform chromitites in the Dagküplü and Kavak mines, Eskisehir ophiolite (NW-Turkey) : genetic implications of mineralogical and geochemical data

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    Mantle tectonites from Eskisehir (NW-Turkey) include high-Cr chromitites with limited variation of Cr#, ranging from 65 to 82. Mg# ratios are between 54 and 72 and chromite grains contain up to 3.71 wt% Fe2O3 and 0.30 wt% TiO2. PGE contents are variable and range from 109 to 533 pbb. Chondrite-normalized PGE patterns are flat from Os to Rh and negatively sloping from Rh to Pd. Total PGE contents and low Pd/Ir ratios (from 0.07 to 0.41) of chromitites are consistent with typical ophiolitic chromitites. Chromite grains contain a great number of solid inclusions. They comprise mainly of highly magnesian (Mg# 95-98) mafic silicates (olivine, amphibole and clinopyroxene) and base-metal sulfide inclusions of millerite (NiS), godlevskite (Ni7S6), bornite (C5FeS4) with minor Ni arsenides of maucherite (Ni11As8) and orcelite (Ni5-xAs2), and unnamed Cu2FeS3 phases. Heazlewoodite, awaruite, pyrite, and rare putoranite (Cu9Fe,Ni9S16) were also detected in the matrix of chromite as secondary minerals. Laurite [(Ru,Os)S2] was the only platinum-group minerals found as primary inclusions in chromite. They occur as euhedral to subhedral crystals trapped within chromite grains and are believed to have formed in the high temperature magmatic stage during chromite crystallization. Laurite has limited compositional variation, range between Ru0.94Os0.03Ir0.02S1.95 and Ru0.64Os0.21Ir0.10S1.85, and contain up to 1.96 at% Rh and 3.67 at% As. Close association of some laurite grains with amphibole and clinopyroxene indicates crystallization from alkali rich fluid bearing melt in the suprasubduction environment. The lack of any IPGE alloys, as well as the low Os-content of laurite, assumes that the melt from which chromite and laurite were crystallized had relatively high fS2 but never reached the fS2 to crystallize the erlichmanite. The presence of millerite, as primary inclusions in chromite, reflects the increasing fS2 during the chromite crystallization

    Exotic accessory minerals in layered chromitites of the Campo Formoso complex (Brazil)

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    The Campo Formoso stratiform intrusive complex, in Bahia State, Brazil, considered to be of Paleoproterozoic age, consists of a tabular body of ultramafic rocks about 40 km long and 100-1100 m wide. Thick horizons of chromitite are exploited and the deposits are the richest in Brazil. The complex was intruded by the Campo Formoso calc-alkaline batholith, emplaced by the result of the Transamazonian collision-related orogeny. The peridotite was firstly thoroughly serpentinized, then affected by a renewed cycle of hydrothermal alteration as the batholith cooled, leading in the roof zone to emerald mineralization around roof pendants. An even later influx of fluid led to the formation of talc, silica and carbonates, such that the ultramafic rocks were locally converted to listwanite. The chromitite sequences are highly unusual in containing rather exotic minerals, such as monazite-(La), monazite-(Ce), apatite, galena, bismuthinite, antimony, and three unknown minerals of stoichiometry PbSb2, Pb Sb and PbSb4, all associated with the clinochlore. The latter phases may have formed during hydrothermal activity in the system Pb-Sb. The presence of these exotic minerals in chromitite, which makes this occurrence unique in the world, strongly support the hypothesis that the La, Ce, P, Pb, Bi and Sb were metasomatically added to the Campo Formoso chromitite horizons by hydrothermal fluids emanating from the nearby Campo Formoso calc-alkaline batholith as it cooled

    Clinical implementation of the hysteroscopic morcellator for removal of intrauterine myomas and polyps. A retrospective descriptive study

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    The aim of this study is to report our experience with a novel technique, the hysteroscopic morcellator (HM), for removal of intrauterine myomas and polyps. We performed a retrospective study on 315 women undergoing operative hysteroscopy with the HM in our university-affiliated teaching hospital. We collected data on installation and operating times, fluid deficit, peri- and postoperative complications. In 37 patients undergoing myomectomy with the HM, mean installation time was 8.7 min, mean operating time, 18.2 min, and median fluid deficit, 440 mL. Three out of 37 HM procedures were converted to resectoscopy, related to a type 2 myoma. In 278 patients, mean installation and operating times for polypectomy with the HM were 7.3 min and 6.6 min, respectively. All procedures were uneventful. Implementation of the HM for removal of type 0 and 1 myomas ≤3 cm, and removal of polyps appears safe and effective

    Grammatikopoulosite, NiVP, a New Phosphide from the Chromitite of the Othrys Ophiolite, Greece

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    Grammatikopoulosite, NiVP, is a new phosphide discovered in the podiform chromitite and hosted in the mantle sequence of the Othrys ophiolite complex, central Greece. The studied samples were collected from the abandoned chromium mine of Agios Stefanos. Grammatikopoulosite forms small crystals (from 5 μm up to about 80 μm) and occurs as isolated grains. It is associated with nickelphosphide, awaruite, tsikourasite, and an undetermined V-sulphide. It is brittle and has a metallic luster. In plane-polarized light, it is creamy-yellow, weakly bireflectant, with measurable but not discernible pleochroism and slight anisotropy with indeterminate rotation tints. Internal reflections were not observed. Reflectance values of mineral in air (R1, R2 in %) are: 48.8–50.30 at 470 nm, 50.5–53.5 at 546 nm, 51.7–55.2 at 589 nm, and 53.2–57.1 at 650 nm. Five spot analyses of grammatikopoulosite give the average composition: P 19.90, S 0.41, Ni 21.81, V 20.85, Co 16.46, Mo 16.39, Fe 3.83, and Si 0.14, total 99.79 wt %. The empirical formula of grammatikopoulosite—based on Σ(V + Ni + Co + Mo + Fe + Si) = 2 apfu, and taking into account the structural results—is (Ni0.57Co0.32Fe0.11)Σ1.00(V0.63Mo0.26Co0.11)Σ1.00(P0.98S0.02)Σ1.00. The simplified formula is (Ni,Co)(V,Mo)P and the ideal formula is NiVP, which corresponds to Ni 41.74%, V 36.23%, P 22.03%, total 100 wt %. The density, calculated on the basis of the empirical formula and single-crystal data, is 7.085 g/cm3. The mineral is orthorhombic, space group Pnma, with a = 5.8893(8), b = 3.5723(4), c = 6.8146(9) Å, V = 143.37(3) Å3, and Z = 4. The mineral and its name have been approved by the Commission of New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2019-090). The mineral honors Tassos Grammatikopoulos, geoscientist at the SGS Canada Inc., for his contribution to the economic mineralogy and mineral deposits of Greece.This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

    Impact of comprehensive pulmonary rehabilitation on anxiety and depression in hospitalized COPD patients.

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    To prospectively evaluate the effect of inpatient pulmonary rehabilitation (iPR) on anxiety and depression as outcome measures in patients with COPD, we studied 149 consecutive adults COPD referred to our iPR after an exacerbation. Patients were divided according to the GOLD staging into: Group 1 (stage 2a, n = 48, FEV1 63 +/- 9% pred.), Group 2 (stage 2b, n = 53, FEV1 42 +/- 6% pred.) and Group 3 (stage 3, n = 48, FEV1 25 +/- 7% pred.). The iPR consisted of twelve 3-hours daily sessions. Hospital Anxiety Depression (HAD) Scale as well as 6-minute walk (6MWD) with evaluation of dyspnea (D) and leg fatigue (F) at rest and end of effort, and health related quality of life by means of St. George Respiratory Questionnaire (SGRQ) were assessed before (T0) and after (T1) the iPR. 6MWD, D and F at end of effort and SGRQ total score similarly improved (p < 0.001) in all groups after iPR. The mean level of HAD-anxiety (from 9.1 +/- 4.0 to 7.7 +/- 3.5, from 9.0 +/- 4.6 to 7.2 +/- 4.6 and from 8.1 +/- 4.1 to 6.7 +/- 4.3 in group 1,2 and 3 respectively) and HAD-depression (from 9.4 +/- 3.5 to 8.2 +/- 3.5, from 9.1 +/- 4.2 to 8.2 +/- 4.5 and from 9.0 +/- 4.0 to 7.4 +/- 4.5 respectively) similarly changed (p < 0.0001) over time in all groups. The total percentage of patients with abnormal score (> 10) of HAD-anxiety (from 31% to 21%) and HAD-depression (from 30% to 22%) significantly decreased (p < 0.05) after the iPR. Inpatient pulmonary rehabilitation may improve levels of anxiety and depression as well as symptoms, exercise capacity and health related quality of life in moderate to severe COPD patients after an acute exacerbation

    Eliopoulosite, V7S8, A New Sulfide from the Podiform Chromitite of the Othrys Ophiolite, Greece

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    The new mineral species, eliopoulosite, V7S8, was discovered in the abandoned chromium mine of Agios Stefanos of the Othrys ophiolite, located in central Greece. The investigated samples consist of massive chromitite hosted in a strongly altered mantle tectonite, and are associated with nickelphosphide, awaruite, tsikourasite, and grammatikopoulosite. Eliopoulosite is brittle and has a metallic luster. In plane-reflected polarized light, it is grayish-brown and shows no internal reflections, bireflectance, and pleochroism. It is weakly anisotropic, with colors varying from light to dark greenish. Reflectance values of mineral in air (Ro, Re’ in %) are: 34.8–35.7 at 470 nm, 38–39 at 546 nm, 40–41.3 at 589 nm, and 42.5–44.2 at 650 nm. Electron-microprobe analyses yielded a mean composition (wt.%) of: S 41.78, V 54.11, Ni 1.71, Fe 1.1, Co 0.67, and Mo 0.66, totali 100.03. On the basis of Σatoms = 15 apfu and taking into account the structural data, the empirical formula of eliopoulosite is (V6.55Ni0.19Fe0.12Co0.07Mo0.04)Σ = 6.97S8.03. The simplified formula is (V, Ni, Fe)7S8 and the ideal formula is V7S8, which corresponds to V 58.16%, S 41.84%, total 100 wt.%. The density, based on the empirical formula and unit-cell volume refined form single-crystal structure XRD data, is 4.545 g·cm−3. The mineral is trigonal, space group P3221, with a = 6.689(3) Å, c = 17.403(6) Å, V = 674.4(5) Å3, Z = 3, and exhibits a twelve-fold superstructure (2a × 2a × 3c) of the NiAs-type subcell with V-atoms octahedrally coordinated by S atoms. The distribution of vacancies is discussed in relation to other pyrrhotite-like compounds. The mineral name is for Dr. Demetrios Eliopoulos (1947–2019), a geoscientist at the Institute of Geology and Mineral Exploration (IGME) of Greece and his widow, Prof. Maria Eliopoulos (nee Economou, 1947), University of Athens, Greece, for their contributions to the knowledge of ore deposits of Greece and to the mineralogical, petrographic, and geochemical studies of ophiolites, including the Othrys complex. The mineral and its name have been approved by the Commission of New Minerals, Nomenclature, and Classification of the International Mineralogical Association (No. 2019-96).© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)

    Out-of-hospital helmet CPAP in acute respiratory failure reduces mortality: a study led by nurses

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    Background and Aim. Acute respiratory failure (ARF) is a condition that must be treated as quickly as possible. Continuous Positive Airway Pressure (CPAP) is a common method used to treat ARF in hospital. The main objective of our study was to investigate the effect of CPAP prior to admission to the emergency room, on the reduction of endotracheal intubation, in-hospital mortality and on the length of stay in hospital (HLOS). Methods. A prospective, observational (non-randomised) study with a historical control group. Data from 3 groups of patients with ARF, irrespective of cause, was collected: pre-hospital CPAP (PHCPAP) group, i.e. 35 patients treated with a helmet CPAP in the ambulance, by trained nurses (mean age, years 80.1±7.9 SD; 14 males); hospital CPAP (HCPAP) group, i.e. 46 patients treated with helmet CPAP in the hospital emergency room (mean age 78.6±6.9 SD; 27 males), and a historical control group of 125 patients treated with medical therapy only (mean age 76.7±5.5 SD; 52 males). CPAP was delivered via a helmet interface. Results. Compared with standard medical therapy, helmet CPAP (pre and in-hospital) reduced mortality by 77 % (p=0.005), while pre-hospital helmet CPAP reduced it by 94% (p=0.011), after adjustment for age, sex, severity of clinical conditions at entry and diagnosis upon admission. HLOS was reduced, compared with standard medical therapy, by 63.5% and by 66% (adjusting for age, sex, severity of clinical conditions at entry and diagnosis at admission) with helmet CPAP (pre and in-hospital) and with helmet CPAP in the ambulance, respectively (p<0.0001). Conclusions. Treating patients with ARF of any cause, with CPAP by trained nurses, before hospital admission, is safe, reduces mortality and the length of stay needed in hospital
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