1,721,027 research outputs found
Nomenclature tunings in the hollandite supergroup
No full textThe hollandite supergroup includes a number of manganese (IV) and titanium oxides, often referred to as tunnel oxides due to their structural features, i.e. octahedral walls, 2x2 octahedra wide, cross-linked to each other to build up a tunnel structure. Tunnels host mono- and divalent cations, and water molecules. Based on the nature of the tunnel cation, the generic formula of these minerals may be written as either A2+[M4+6M3+2]O16 (more rarely, A2+[M4+7M2+]O16) or A+[M4+7M3+]O16 (more rarely, A+[M4+7.5M2+0.5]O16), where A2+ = Pb, Ba, Sr; A+ = K, Na; M4+ = Mn, Ti; M3+ = Mn, Fe, Cr, V; M2+ = Fe. The hollandite supergroup is divided into two groups depending on the dominant tetravalent cation in the octahedral walls: the coronadite group (M4+ = Mn), and the priderite group (M4+ = Ti). Two main considerations led to the preparation of this report: (i) M3+ (or M2+) cations, even if they share the same site as M4+, are essential for charge-balance, therefore each combination of dominant A2+ (or A+), M4+, and M3+ (or M2+) cations corresponds to a distinct species; (ii) the presence/absence of ‘‘zeolitic’’ water in the tunnels should not represent the discriminant between two species. Based on these guidelines, our main actions have been the following: hollandite is redefined as the Ba-Mn3+ end-member of the coronadite group; concurrently, type hollandite is redefined as ferrihollandite, a new name to denote the Ba-Fe3+ end-member; ankangite is discredited, as a H2O-free variety of mannardite; the ideal endmember formulae of all known minerals of the hollandite supergroup are defined; six potentially new mineral species in the hollandite supergroup are envisaged. This report has been approved by the IMA CNMNC
Crystal structure of hollandite from Vagli (Apuan Alps) and potentially new mineral species in the hollandite group
No full textPredictive biomarkers for checkpoint inhibitor-based immunotherapy: The Galectin-3 signature in NSCLCs
Full text linkCheckpoint inhibitor-based immunotherapy is opening a promising scenario in oncology, with objective responses registered in multiple cancer types. However, reliable predictive markers of tumor responsiveness are still lacking. These markers need to be urgently identified for a better selection of patients that can be candidates for immunotherapy. In this pilot study, a cohort of 34 consecutive patients bearing programmed death-ligand 1 (PD-L1)-positive non-small cell lung carcinoma (NSCLC), treated with pembrolizumab, was considered. The retrospective immuno-phenotypic analysis performed on the original tumor biopsies allowed for the identification of a specific “galectin signature”, which strongly correlated with tumor responsiveness to anti PD-1 immunotherapy. We observed that the large majority of patients (about 90%) with high galectin-3 tumor expression (score 3+) showed an early and dramatic progression of the disease after three cycles of treatments. In contrast, all patients with negative or low/intermediate expression of galectin-3 in tumor cells showed an early and durable objective response to pembrolizumab, indicating galectin-3 as an interesting predictive marker of tumor responsiveness. The galectin-3 signature, at least in NSCLCs, promises a better selection of patient candidates for immunotherapy, reducing unnecessary treatment exposures and social costs. A large multicenter study is ongoing to validate this finding
Ferrihollandite, BaMn4+6Fe3+2O16, from Apuan Alps, Tuscany, Italy: description and crystal structure
No full textThe recent revisitation of the nomenclature of tunnel oxides belonging to the hollandite supergroup led to the definition of a
new end-member, ferrihollandite, ideally BaMn4þ6Fe3þ2O16. In particular, the type hollandite from Kajlidongri, Jhabua District,
Madhya Pradesh, India, proved to be ferrihollandite. A new occurrence of ferrihollandite is here described from the manganese hydrothermal ores from Vagli, Apuan Alps, Tuscany, Italy, on the basis of chemical and X-ray diffraction data. Electron-microprobe data point to the following composition (in wt%): TiO2 3.06, MnO2 58.83, Mn2O3 8.64, Fe2O3 9.76, Al2O3 0.79, ZnO 0.03, SrO 2.77, BaO 14.63, Na2O 0.09, K2O 0.05, sum 98.65. The structural formula, based on 16 oxygen atoms and 8 octahedral cations per formula unit, is (Ba0.793Sr0.222Na0.024K0.009)1⁄41.048(Mn4þ5.624Ti0.318Fe3þ
1.016Mn3þ0.910Al0.129Zn0.003)1⁄48.000O16. The TG-DSC data show three main endothermic processes, related to the loss of water and the release of oxygen upon heating. The total mass loss is9.7 wt% in the temperature range between 25 and 1200 C; the mass loss related to the release of water is 1.5 wt%. Single-crystal X-ray diffraction study gives a monoclinic unit cell, a 10.0001(7), b 5.7465(4), c 9.8076(8) A ° , b 90.713(2), V 563.56(2) A ° 3, space group P2/n. The crystal structure has been solved and refined on the basis of 1675 observed reflections, with a final R1 1⁄4 0.037. The basic structural features of ferrihollandite are the same as the 2.9A ° hollandite-type compounds, but with long-range ordering of the tunnel cations. The occurrence of superstructure reflections could be related to the ordered sequence Ba–H2O–Ba–H2O within the tunnels
La mode au défi de l’histoire économique: la mode et l’économie italienne (XIX-XX siècle
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
