Exploring Epitaxial Structures for Electrically Pumped Perovskite Lasers: A Study of CsPb(Br,I) Based on the Bethe-Salpeter Equation.

Halide perovskites are widely used as components of electronic and optoelectronic devices such as solar cells, light-emitting diodes (LEDs), optically pumped lasers, field-effect transistors, photodetectors, and γ-detectors. Despite this wide range of applications, the construction of an electrically pumped perovskite laser remains challenging. In this paper, we numerically justify that mixing two perovskite compounds with different halide elements can lead to optical properties suitable for electrical pumping.

Role of inorganic cations in the excitonic properties of lead halide perovskites.

We theoretically investigate lead iodide perovskites of general formula APbI for a series of metallic cations (namely Cs, Rb, K, Na and Li) by means of density functional theory, the GW method and the Bethe-Salpeter equation including spin-orbit coupling. We demonstrate that the low-energy edges (up to 1.3 eV) of the absorption spectra are dominated by weakly bound excitons, with binding energies of ∼ 30-80 meV, and the corresponding intensities increase as metallic cations become lighter.

Polarization-dependent excitons and plasmon activity in nodal-line semimetal ZrSiS.

The optical properties of the bulk ZrSiS nodal-line semimetal are theoretically studied within a many-body formalism. The bands are similar to those calculated within the density functional theory, except near the -point; in particular, no significant differences are found around the Fermi energy. On the other hand, the solution of the Bethe-Salpeter equation reveals significant excitonic activity, mostly as dark excitons which appear in a wide energy range.

Investigating charge carrier scattering processes in anisotropic semiconductors through first-principles calculations: the case of p-type SnSe.

Efficient ab initio computational methods for the calculation of the thermoelectric transport properties of materials are of great interest for energy harvesting technologies. The constant relaxation time approximation (CRTA) has been largely used to efficiently calculate thermoelectric coefficients. However, CRTA usually does not hold for real materials.

Implementation of a new Single-Pass Whole-Body Computed Tomography Protocol: Is it safe, effective and efficient in patients with severe trauma?

Purpose: The objective of this study was to evaluate the implementation of a new single-pass whole-body computed tomography Protocol in the management of patients with severe trauma.

Methods: This was a descriptive evaluation of polytrauma patients who underwent whole-body computed tomography. Patients were divided into three groups: 1.

The critical threshold value of systolic blood pressure for aortic occlusion in trauma patients in profound hemorrhagic shock.

Background: This study aimed to determine the critical threshold of systolic blood pressure (SBP) for aortic occlusion (AO) in severely injured patients with profound hemorrhagic shock.

Methods: All adult patients (>15 years) undergoing AO via resuscitative endovascular balloon occlusion of the aorta (REBOA) or thoracotomy with aortic cross clamping (TACC) between 2014 and 2018 at level I trauma center were included. Patients who required cardiopulmonary resuscitation in the prehospital setting were excluded.

Resuscitative endovascular balloon of the aorta is feasible in penetrating chest trauma with major hemorrhage: Proposal of a new institutional deployment algorithm.

Background: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is an emerging option for hemorrhage control, but its use is limited in scenarios such as penetrating chest trauma. The aim of this study was to describe the use of REBOA as a resuscitative adjunct in these cases with major hemorrhage and to propose a new clinical management algorithm.

Methods: This was a prospective, observational study conducted at a single Level I trauma center in Colombia.

Chest Trauma Outcomes: Public Versus Private Level I Trauma Centers.

Background: The goal of our study was to evaluate the differences in care and clinical outcomes of patients with chest trauma between two hospitals, including one public trauma center (Pu-TC) and one private trauma center (Pri-TC).

Methods: Patients with thoracic trauma admitted from January 2012 to December 2018 at two level I trauma centers (Pu-TC: Hospital Universitario del Valle, Pri-TC: Fundación Valle del Lili) in Cali, Colombia, were included. Multivariable logistic regression was used to assess for differences in in-hospital mortality, adjusting for relevant demographic and clinical characteristics.

The Challenge of Implementing the "Stop the Bleed" Campaign in Latin America.

Background: Currently, several initiatives have emerged to empower the public to act as immediate responders in front of hemorrhaging victims. We aimed to evaluate the effectiveness of implementing the Stop the Bleed campaign and the association between the instructors' background and the theoretical and practical competences achieved by the participants in Latin America.

Methods: Medical students and general surgeons taught both allied health students and nonallied health students at a local university; the training had a master class followed by a practical component and a written test, as well as tourniquet placement was tested.

Resuscitative endovascular balloon occlusion of the aorta deployed by acute care surgeons in patients with morbidly adherent placenta: a feasible solution for two lives in peril.

Morbidly adherent placenta (MAP), which includes accreta, increta, and percreta, is a condition characterized by the invasion of the uterine wall by placental tissue. The condition is associated with higher odds of massive post-partum hemorrhage. Several interventions have been developed to improve hemorrhage-related outcomes in these patients; however, there is no evidence to prefer any intervention over another.

A meta-analysis of the incidence of complications associated with groin access after the use of resuscitative endovascular balloon occlusion of the aorta in trauma patients.

Background: Serious complications related to groin access have been reported with the use of resuscitative endovascular balloon occlusion of the aorta (REBOA). We performed a systematic review and meta-analysis to estimate the incidence of complications related to groin access from the use of REBOA in adult trauma patients.

Methods: We identified articles in MEDLINE and EMBASE.

Ultralow and anisotropic thermal conductivity in semiconductor AsSe.

An ultralow lattice thermal conductivity of 0.14 W m K along the b[combining right harpoon above] axis of AsSe single crystals was obtained at 300 K using first-principles calculations involving density functional theory and the resolution of the Boltzmann transport equation. This ultralow lattice thermal conductivity arises from the combination of two mechanisms: (1) a cascade-like fall of the low-lying optical modes, which results in avoided crossings of these with the acoustic modes, low sound velocities and increased scattering rates of the acoustic phonons; and (2) the repulsion between the lone-pair electrons of the As cations and the valence p orbitals of the Se anions, which leads to an increase in the anharmonicity of the bonds.

Insights into the thermoelectric properties of SnSe from ab initio calculations.

The thermoelectric properties of SnSe are studied by first-principles methods using an original methodology. We computed first the electronic structure of the system, which justifies its macroscopic anisotropy; the inclusion of van der Waals dispersive corrections improves the agreement of the structural parameters with experiments. The Seebeck coefficient and the electrical and thermal conductivities of single crystals and polycrystals are subsequently described in good agreement with experimental data.

Chronology of metastasis in cutaneous melanoma: growth rate model.

In humans, it is not possible to obtain experimental evidence of when a cancer begins to metastasize. The purpose of this study was to estimate the time of onset of metastatic dissemination in cutaneous melanoma using a model based on its growth rate (GR). The critical time of onset of metastatic dissemination below which no cases of fatal melanomas were seen may be described with a potential function in which this time is inversely proportional to the GR.