High-risk pulmonary embolism in a post-operative patient.

Despite a rapidly evolving role for advanced therapeutic interventions, the majority of patients with high-risk pulmonary embolism (PE) are still undertreated. Due to complex diagnosis and management, along with a high associated mortality rate, high-risk PE offers an excellent opportunity for simulation training. We present a simulated case of high-risk PE in a post-operative patient that is designed to teach key principles of diagnosis and management.

Just-in-Time Simulation Training to Augment Overnight ICU Resident Education.

Patients who decompensate overnight experience worse outcomes than those who do so during the day. Just-in-time (JIT) simulation could improve on-call resident preparedness but has been minimally evaluated in critical care medicine (CCM) to date. To determine whether JIT training can improve residents' performance in simulation and if those skills would transfer to better clinical management in adult CCM.

Decoupling 1D and 2D features of 2D sp-nanoribbons-the megatom model.

The dependence of the electron energy band gap on the width of an-nanoribbon is investigated using a generalization of the 1D tight binding model for a chain of atoms. Within the proposed generalization, small linear atomic formations along lines perpendicular to the 2D ribbon axis are modeled as single large atoms calledwhose properties depend on the type, the size and the atomic conformation. Replacement of a 1D chain of atoms by that of the megatoms is accompanied by the incorporation of zeroth order 2D features into the 1D model approximation of the nanoribbon.

Magnetism versus band-gap relationship in diluted magnetic semiconductors: megatom impurity behavior of the magnetic dopant complexes.

An analysis ofnumerical results obtained for the total energy of diluted magnetic semiconductors (DMSs) doped with dopant formations of various structural and spin conformations consisting of 2-4 3D transition metal (TM atoms) has revealed that a dopant formation acts as large impurity atom i.e., as a, in a reverse analogy to the process of the adsorption of-atoms onto metallic surfaces.

Codoping induced enhanced ferromagnetism in diluted magnetic semiconductors.

The experimentally observed-magnetism and its subsequent attribution to the presence of structural and topological defects has opened the way for engineering the magnetic properties of diluted magnetic semiconductors (DMSs) and transition metal oxides (TMOs). Doping and codoping constitute the most commonly used processes (either experimentally or theoretically) for developing and studying this type of defect-induced magnetism. The focus of the present review is to highlight the basic features of the defect magnetism which have been observed over diverse systems, while emphasizing the local, holistic and synergistic response of the host materials to their doping and investigating their role in the development of the magnetic coupling (MC) that is developed among the magnetic dopants.

High temperature stability, metallic character and bonding of the SiBN planar structure.

The family of monolayered SiBN structures constitute a new class of 2D materials exhibiting metallic character with remarkable stability. Topologically, these structures are very similar to graphene, forming a slightly distorted honeycomb lattice generated by a union of two basic motifs with AA and AB stacking. In the present work we study in detail the structural and electronic properties of these structures in order to understand the factors which are responsible for their structural differences as well as those which are responsible for their metallic behavior and bonding.

Estimation of-exchange constants revisited.

We present a new computational method for estimating the-exchange constant,Jeffsp-d, applicable to transition metal doped diluted magnetic semiconductors, transition metal oxides, and 2D- and 3D- dichalcogenides. The proposed method is based on results describing the variation of the magnetic features of a doped system with the variation of its magnetization density (). The results forJeffsp-d(M)obtained with the proposed method are compared with the corresponding results,Jeffsp-d(ΔEVBM), obtained from estimations of the spin electron orbital splitting, Δ, at the valence band maximum (VBM).

Goodenough-Kanamori rules applied to wurtzite crystals.

Goodenough-Kanamori (GK) criteria have provided a significant contribution to our understanding of the importance of the symmetry and the electron orbital characteristics in the development of the magnetic superexchange coupling [antiferromagnetic (AFM) or ferromagnetic (FM)] applied primarily to systems with bond angles of 180° and 90°. In the present work, we quantify and apply the GK criteria to wurtzite systems. Our approach is based on calculations of (i) the spin electron densities of the anions which are first nearest neighbors (1nn) to the magnetic dopants and, (ii) the generalized exchange integrals which are derived by investigating the electronic properties of the systems under a magnetization density constraint.

Data driven modeling of magnetism in dilute magnetic semiconductors: correlation between the magnetic features of diluted magnetic semiconductors and electronic properties of the constituent atoms.

We propose an efficient machine learning based approach in modeling the magnetism of diluted magnetic semiconductors (DMSs) leading to the prediction of new compounds with enhanced magnetic properties. The approach combines accurate ab initio methods with statistical tools to uncover the correlation between the magnetic features of DMSs and electronic properties of the constituent atoms to determine the underlying factors responsible for the DMS-magnetism. Taking the electronic properties of different DMS systems as descriptors to train different regression models allows us to achieve a speed up of several orders of magnitude in the search for an optimum combination of the host semiconductor and the dopants with enhanced magnetic properties.

Development and Evaluation of a Cognitive Aid Booklet for Use in Rapid Response Scenarios.

Introduction: Rapid response teams (RRTs) have become ubiquitous among hospitals in North America, despite lack of robust evidence supporting their effectiveness. Many RRTs do not yet use cognitive aids during these high-stakes, low-frequency scenarios, and there are no standardized cognitive aids that are widely available for RRTs on medicine patients. We sought to design an emergency manual to improve resident performance in common RRT calls.

Antiferromagnetic successive superexchange interactions underlying ferromagnetic couplings in codoped diluted magnetic semiconductors.

Our recent works have revealed that the magnetic coupling among the magnetic codopants in diluted magnetic semiconductors and doped transition metal oxides has a strong local feature. This was attributed to successive spin polarizations induced by the codopants to their neighboring anion ligands. In the present work, we analyze and refine the successive spin polarization based magnetic coupling using results of ab initio calculations and assign the magnetic coupling among the magnetic codopants to a combination of superexchange and double-exchange interactions.

Universal features underlying the magnetism in diluted magnetic semiconductors.

Investigation of a diverse variety of wide band gap semiconductors and metal oxides that exhibit magnetism on substitutional doping has revealed the existence of universal features that relate the magnetic moment of the dopant to a number of physical properties inherent to the dopants and the hosts. The investigated materials consist of ZnO, GaN, GaP, TiO, SnO, SnN, MoS, ZnS and CdS doped with 3d-transition metal atoms. The primary physical properties contributing to magnetism include the orbital hybridization and charge distribution, the d-band filling, d-band center, crystal field splitting, electron pairing energy and electronegativity.

Direct Band Gap Gallium Antimony Phosphide (GaSbxP(1-x)) Alloys.

Here, we report direct band gap transition for Gallium Phosphide (GaP) when alloyed with just 1-2 at% antimony (Sb) utilizing both density functional theory based computations and experiments. First principles density functional theory calculations of GaSbxP(1-x) alloys in a 216 atom supercell configuration indicate that an indirect to direct band gap transition occurs at x = 0.0092 or higher Sb incorporation into GaSbxP(1-x).

ZnO gap engineering by doping with III-V compounds.

Gap engineering of ZnO by codoping it with III-V materials is investigated using model and ab initio calculation. Our results show that the codoped materials (ZnO)1-x (III-V)x , where (III-V) stands for GaN, AlN, AlP, BN, BP exhibit energy band gaps that get smaller as the dopant concentrations x is increased. Even at a very small dopant concentration the obtained band gaps are found to be much smaller than that of ZnO making the studied (ZnO)1-x(III-V)x materials promising candidates for photoelectrochemical water splitting.

Successive spin polarizations underlying a new magnetic coupling contribution in diluted magnetic semiconductors.

We propose a new type of magnetic coupling (MC) that is found in diluted magnetic semiconductors (DMSs). The origin of this is found to be the result of charge transfer processes followed by successive spin polarizations (SSPs) along successive cation-anion segments which include the impurities. The basic process underlying the SSP-based MC (SSP-MC) is the sharing of a single spin orbital by two neighboring impurities.

Informatics guided discovery of surface structure-chemistry relationships in catalytic nanoparticles.

A data driven discovery strategy based on statistical learning principles is used to discover new correlations between electronic structure and catalytic activity of metal surfaces. From the quantitative formulations derived from this informatics based model, a high throughput computational framework for predicting binding energy as a function of surface chemistry and adsorption configuration that bypasses the need for repeated electronic structure calculations has been developed.

New visible light absorbing materials for solar fuels, Ga(Sbx)N1-x.

A novel visible-light-absorbing dilute alloy, Ga(Sbx)N1-x is synthesized by metal organic chemical vapor deposition (MOCVD) for solar hydrogen production. Significant bandgap reduction of GaN, from 3.4 eV to 1.

Band alignment and optical absorption in Ga(Sb)N alloys.

We extend the theory of band alignment proposed by Harrison to ternary and quaternary heteropolar semiconductors. Combining this with first-principles density functional theory incorporating the LDA/GGA+U formalism (LDA: local density approximation; GGA: generalized gradient approximation) can result in useful electronic structure predictions for new alloys. The practicality of this is demonstrated by application to the Ga(Sbx)N1-x alloys, where the feasibility of water splitting reaction under visible light irradiation is discussed.

The synergistic character of the defect-induced magnetism in diluted magnetic semiconductors and related magnetic materials.

In this work, we introduce a new perspective in explaining the origin of magnetism in dilute magnetic semiconductors, carbon-based materials and other related materials. According to our proposal, the magnetism in these materials is the result of the synergistic action of defect-induced electronic processes mostly of local character which can provide magnetic moments and develop a ferromagnetic coupling among them. This synergy is realizable via appropriate codoping which appears as a general and generic approach.

Magnetic anisotropy and engineering of magnetic behavior of the edges in Co embedded graphene nanoribbons.

Using first-principles calculations, we demonstrate the existence of anisotropic ferromagnetic interactions in Co embedded graphene nanoribbons (GNRs). Spin polarization of the edge states is found to alter significantly compared to the metal-free cases. Our findings can all be well-justified as the output of the interplay between the development of an induced spin polarization in the neighborhood of the Co atoms and the maintaining of the polarization picture of the Co-free GNR.

Symmetry-switching molecular Fe(O2)n(+) clusters.

Experimental and theoretical studies based on mass spectrometry, collision-induced dissociation, and ab initio calculations are performed on the formation and stability of FeO(n)(+) clusters, as well as on their structural, electronic, and magnetic properties. In the mass spectra, clusters with an even number of oxygen atoms show increased stability, most prominently for FeO(10)(+). The extra stability of this cluster is confirmed by measurements of fragmentation cross sections through crossed molecular beam experiments.

Ferromagnetic interactions in hosted bipartite materials--generalized-double-exchange and generalized-superexchange interactions.

Defect-induced magnetism in dilute magnetic semiconductors challenges our understanding of magnetism in solids. Theories based on conventional superexchange or double-exchange interactions cannot explain long range magnetic order at concentrations below the percolation threshold in these materials. On the other hand, the codoping-induced magnetism, which can explain magnetic interactions below the percolation threshold, has eluded explanation.

Defect-induced defect-mediated magnetism in ZnO and carbon-based materials.

The recent discovery of magnetism in a variety of diverse non-magnetic materials containing defects has challenged conventional thinking about the microscopic origin of magnetism in general. Especially intriguing is the complete absence of d electrons that are traditionally associated with magnetism. By a systematic microscopic investigation of two completely dissimilar materials (namely, ZnO and rhombohedral-C(60) polymers) exhibiting ferromagnetism in the presence of defects, we show that this new phenomenon has a common origin and the mechanism responsible can be used as a powerful tool for inducing and tailoring magnetic features in systems which are not magnetic otherwise.

Identification of descriptors for the CO interaction with metal nanoparticles.

The design and performance optimization of future nanocatalysts will depend on our understanding of adsorbate-metal interactions. Using first principle calculations, we identify suitable descriptors, namely, the coordination number and curvature angle of the surface Au atoms, capable of predicting the CO binding strength on every site of Au nanoparticles. Our results unravel how the size, shape, and symmetry of nanoparticles affect their electronic properties and, consequently, their interaction with CO.

Vortex formation and recirculation zones in left anterior descending artery stenoses: computational fluid dynamics analysis.

Flow patterns may affect the potential of thrombus formation following plaque rupture. Computational fluid dynamics (CFD) were employed to assess hemodynamic conditions, and particularly flow recirculation and vortex formation in reconstructed arterial models associated with ST-elevation myocardial infraction (STEMI) or stable coronary stenosis (SCS) in the left anterior descending coronary artery (LAD). Results indicate that in the arterial models associated with STEMI, a 50% diameter stenosis immediately before or after a bifurcation creates a recirculation zone and vortex formation at the orifice of the bifurcation branch, for most of the cardiac cycle, thus allowing the creation of stagnating flow.