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It is still debated whether prophylactic doses of low-molecular- weight heparin (LMWH) are always effective in preventing Venous Thromboembolism (VTE) and mortality in COVID-19. Furthermore, there is paucity of data for those patients not requiring ventilation. We explored mortality and the safety/efficacy profile of LMWH in a cohort of Italian patients with COVID-19 who did not undergo ventilation. From the initial cohort of 422 patients, 264 were enrolled. Most (n = 156, 87.7%) received standard LMWH prophylaxis during hospitalization, with no significant difference between medical wards and Intensive Care Unit (ICU). Major or not major but clinically relevant hemorrhages were recorded in 13 (4.9%) patients: twelve in those taking prophylactic LMWH and one in a patient taking oral anticoagulants (p: n.s.). Thirty-nine patients (14.8%) with median age 75 years. were transfused. Hemoglobin (Hb) at admission was significantly lower in transfused patients and Hb at admission inversely correlated with the number of red blood cells units transfused (p < 0.001). In-hospital mortality occurred in 76 (28.8%) patients, 46 (24.3%) of whom admitted to medical wards. Furthermore, Hb levels at admittance were significantly lower in fatalities (g/dl 12.3; IQR 2.4 vs. 13.3; IQR 2.8; Mann–Whitney U-test; p = 0.001). After the exclusion of patients treated by LMWH intermediate or therapeutic doses (n = 32), the logistic regression showed that prophylaxis significantly and independently reduced mortality (OR 0.31, 95% CI 0.13–0.85). Present data show that COVID-19 patients who do not require ventilation benefit from prophylactic doses of LMWH.

The simple chemistry and structure of quartz together with its abundance in nature and its piezoelectric properties make convenient its employment for several applications, from engineering to Earth sciences. For these purposes, the quartz equations of state, thermoelastic and thermodynamic properties have been studied since decades. Alpha quartz is stable up to 2.5 GPa at room temperature where it converts to coesite, and at ambient pressure up to 847 K where it transforms to the beta phase. In particular, the displacive phase transition at 847 K at ambient pressure is driven by intrinsic anharmonicity effects (soft-mode phase transition) and its precise mechanism is difficult to be investigated experimentally. Therefore, we studied these anharmonic effects by means of ab initio calculations in the framework of the statistical thermodynamics approach. We determined the princi-pal thermodynamic quantities accounting for the intrinsic anharmonicity and compared them against experimental data. Our results up to 700 K show a very good agreement with experiments. The same procedures and algorithms illustrated here can also be applied to determine the thermodynamic properties of other crystalline phases possibly affected by intrinsic anharmonic effects, that could partially invalidate the standard quasi-harmonic approach.

The study of the effects of non-hydrostatic stresses on rock-forming minerals is fundamental for understanding how minerals respond to tectonic stresses in the Earth’s interior. Larger deviatoric stresses of the order of GPa can arise from physical interaction between minerals (e.g. host–inclusion systems, compositional gradients) at the micrometric scale, even if at the large-scale large stresses are annealed by plastic flows. Thus, experimental data under hydrostatic pressure do not provide us access to all the possible modifications and structural changes experienced by minerals subjected to deviatoric stresses. Therefore, we carried out ab initio hybrid Hartree–Fock/Density Functional Theory simulations to determine the properties of alpha-quartz, since it is one of the most abundant minerals in the Earth’s crust with a very simple chemistry and structure. We calculated its structure, elastic parameters and Raman-active vibrational modes as a function of different applied strains, which allow us to show how phonon frequencies and structural parameters (bond lengths and angles) are affected by deviatoric stress conditions rather than hydrostatic pressure.

Rutile is often found as inclusions in garnet, quartz, and several other rock-forming minerals, and it is also a common accessory phase in high-pressure metamorphic rocks. Its relatively simple structure, chemistry, broad P-T stability field, and its wide occurrence in nature makes it a candidate for the application of elastic geobarometry. However, thermodynamic studies coupled with observations on natural samples predict that rutile inclusions in garnets should exhibit zero residual pressure. This implies that the rutile inclusions are detached from the inclusion walls in the host garnet after entrapment. We determined the elastic and vibrational properties of rutile via ab initio hybrid Hartree-Fock/Density Functional Theory simulations under different strain states. Our results confirmed the thermodynamic behavior of rutile in garnet and allowed us to determine for the first time the components of the phonon-mode Grüneisen tensors of rutile. We demonstrated that pure rutile inclusions in garnets from metamorphic rocks exhibit no residual strain or stress, consistent with thermodynamic modeling. Nevertheless, there are rutile inclusions in garnet surrounded by optical birefringence haloes, which are indicative of residual inclusion pressures. Careful examination of these show that they contain significant amounts of amphibole, which reduce the elastic moduli of the composite inclusion to less than that of the garnet hosts. A calculation method for the residual pressures of multi-phase inclusions is described.