Simple Metals at High Pressure

In this lecture we review high-pressure phase transition sequences exhibited by simple elements, looking at the examples of the main group I, II, IV, V, and VI elements. General trends are established by analyzing the changes in coordination number on compression. Experimentally found phase transitions and crystal structures are discussed with a brief description of the present theoretical picture.Comment: 22 pages, 4 figures, lecture notes for the lecture given at the Erice course on High-Pressure Crystallography in June 2009, Sicily, Ital

Quantum hydrogen-bond symmetrization in the superconducting hydrogen sulfide system.

The quantum nature of the proton can crucially affect the structural and physical properties of hydrogen compounds. For example, in the high-pressure phases of H2O, quantum proton fluctuations lead to symmetrization of the hydrogen bond and reduce the boundary between asymmetric and symmetric structures in the phase diagram by 30 gigapascals (ref. 3). Here we show that an analogous quantum symmetrization occurs in the recently discovered sulfur hydride superconductor with a superconducting transition temperature Tc of 203 kelvin at 155 gigapascals--the highest Tc reported for any superconductor so far. Superconductivity occurs via the formation of a compound with chemical formula H3S (sulfur trihydride) with sulfur atoms arranged on a body-centred cubic lattice. If the hydrogen atoms are treated as classical particles, then for pressures greater than about 175 gigapascals they are predicted to sit exactly halfway between two sulfur atoms in a structure with Im3m symmetry. At lower pressures, the hydrogen atoms move to an off-centre position, forming a short H-S covalent bond and a longer H···S hydrogen bond in a structure with R3m symmetry. X-ray diffraction experiments confirm the H3S stoichiometry and the sulfur lattice sites, but were unable to discriminate between the two phases. Ab initio density-functional-theory calculations show that quantum nuclear motion lowers the symmetrization pressure by 72 gigapascals for H3S and by 60 gigapascals for D3S. Consequently, we predict that the Im3m phase dominates the pressure range within which the high Tc was measured. The observed pressure dependence of Tc is accurately reproduced in our calculations for the phase, but not for the R3m phase. Therefore, the quantum nature of the proton fundamentally changes the superconducting phase diagram of H3S.We acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (FIS2013- 48286-C2-2-P), French Agence Nationale de la Recherche (Grant No. ANR-13-IS10-0003- 392 01), EPSRC (UK) (Grant No. EP/J017639/1), Cambridge Commonwealth Trust, National Natural Science Foundation of China (Grants No. 11204111, 11404148, and 11274136), and 2012 Changjiang Scholars Program of China. Work at Carnegie was supported by EFree, an Energy Frontier Research Center funded by the DOE, Office of Science, Basic Energy Sciences under Award No. DE-SC-0001057. Computer facilities were provided by the PRACE project AESFT and the Donostia International Physics Center (DIPC).This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/nature1717

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

On the existence of two states in liquid water : impact on biological and nanoscopic systems

This work reviews several properties of liquid water, including the dielectric constant and the proton-spin lattice relaxation, and draws attention to a bilinear behaviour defining a crossover in the temperature range 50 ± 10°C between two possible states in liquid water. The existence of these two states in liquid water plays an important role in nanometric and biological systems. For example, the optical properties of metallic (gold and silver) nanoparticles dispersed in water, used as nanoprobes, and the emission properties of CdTe quantum dots (QDs), used for fluorescence bioimaging and tumour targeting, show a singular behaviour in this temperature range. In addition, the structural changes in liquid water may be associated with the behaviour of biological macromolecules in aqueous solutions and in particular with protein denaturation

Pediatric Medication Noninitiation in Spain.

OBJECTIVES: To estimate medication noninitiation prevalence in the pediatric population and identify the explanatory factors underlying this behavior. METHODS: Observational study of patients (<18 years old) receiving at least 1 new prescription (28 pharmaceutical subgroups; July 2017 to June 2018) in Catalonia, Spain. A prescription was considered new when there was no prescription for the same pharmaceutical subgroup in the previous 6 months. Noninitiation occurred when a prescription was not filled within 1 month or 6 months (sensitivity analysis). Prevalence was estimated as the proportion of total prescriptions not initiated. To identify explanatory factors, a multivariable multilevel logistic regression model was used, and adjusted odds ratios were reported. RESULTS: Overall, 1 539 003 new prescriptions were issued to 715 895 children. The overall prevalence of 1-month noninitiation was 9.0% (ranging from 2.6% [oral antibiotics] to 21.5% [proton pump inhibitors]), and the prevalence of 6-month noninitiation was 8.5%. Noninitiation was higher in the youngest and oldest population groups, in children from families with a 0% copayment rate (vulnerable populations) and those with conditions from external causes. Out-of-pocket costs of drugs increased the odds of noninitiation. The odds of noninitiation were lower when the prescription was issued by a pediatrician (compared with a primary or secondary care clinician). CONCLUSIONS: The prevalence of noninitiation of medical treatments in pediatrics is high and varies according to patients' ages and medical groups. Results suggest that there are inequities in access to pharmacologic treatments in this population that must be taken into account by health care planners and providers