Designing barrier-free metal/MoS2 contacts through electrene insertion.

Transition-metal dichalcogenides (TMDCs), including MoS2, have great potential in electronics applications. However, achieving low-resistance metal contacts is a challenge that impacts their performance in nanodevices due to strong Fermi-level pinning and the presence of a tunnelling barrier. As a solution, we explore a strategy of inserting monolayers of alkaline-earth sub-pnictide electrenes with a general formula of [M2X]+e- (M = Ca, Sr, Ba; X = N, P, As, Sb) between the TMDC and the metal. These electrenes possess two-dimensional sheets of charge on their surfaces that can be readily donated when interfaced with a TMDC semiconductor, thereby lowering its conduction band below the Fermi level and eliminating the Schottky and tunnelling barriers. In this work, density-functional theory (DFT) calculations were performed for metal/electrene/MoS2 heterojunctions for all stable M2X electrenes and both Au and Cu metals. To identify the material combinations that provide the most effective Ohmic contact, the charge transfer, band structure, and electrostatic potential were computed. Linear correlations were found between the charge donated to the MoS2 and both the electrene surface charge and work function. Overall, Ca2N appears to be the most promising electrene for achieving an Ohmic metal/MoS2 contact due to its high surface charge density.

Primary Care for Veterans Experiencing Homelessness: a Narrative Review of the Homeless Patient Aligned Care Team (HPACT) Model.

In 2011, the U.S. Department of Veterans Health (VA) implemented a homeless-tailored primary care medical home model called the Homeless Patient Aligned Care Teams (HPACTs). The impact of HPACTs on health and healthcare outcomes of veterans experiencing homelessness has not been adequately synthesized. This narrative review summarized peer-reviewed studies published in databases Ovid MEDLINE, Ovid EMBASE, and APA PsycInfo from 1946 to February 2022. Only original research studies that reported outcomes of the HPACT model were included in the review. Of 575 studies that were initially identified and screened, 26 studies met inclusion criteria and were included in this review. Included studies were categorized into studies that described the following: (1) early HPACT pilot implementation; (2) HPACT's association with service quality and utilization; and (3) specialized HPACT programs. Together, studies in this review suggest HPACT is associated with reductions in emergency department utilization and improvements in primary care utilization, engagement, and positive patient experiences; however, the methodological rigor of the included studies was low, and thus, these findings should only be considered preliminary. There is a need for randomized controlled trials assessing the impact of the PACT model on key outcomes of interest, as well as to determine whether the model is a viable way to manage healthcare for persons experiencing homelessness outside of the VA system.

Nickel-Catalyzed O-Arylation of Primary or Secondary Aliphatic Alcohols with (Hetero)aryl Chlorides: A Comparison of Ni(I) and Ni(II) Precatalysts.

A comparative experimental and computational study examining the interplay of the ancillary ligand structure and Ni oxidation state in the Ni-catalyzed C(sp2)-O cross-coupling of (hetero)aryl chlorides and primary or secondary aliphatic alcohols is presented, focusing on PAd-DalPhos (L1)-, CyPAd-DalPhos (L2)-, PAd2-DalPhos (L3)-, and DPPF (L4)-ligated [(L)NiCl]n (n = 1 or 2) and (L)Ni(o-tol)Cl precatalysts. Both L1 and L2 were found to outperform the other ligands examined, with the latter proving to be superior overall. While Ni(II) precatalysts generally outperformed Ni(I) species, in some instances the catalytic abilities of Ni(I) precatalysts were competitive with those of Ni(II). Density-functional theory calculations indicate the favorability of a Ni(0)/Ni(II) catalytic cycle featuring turnover-limiting C-O bond reductive elimination over a Ni(I)/Ni(III) cycle involving turnover-limiting C-Cl oxidative addition.

Comparison of Density-Functional Theory Dispersion Corrections for the DES15K Database.

While density-functional theory (DFT) remains one of the most widely used tools in computational chemistry, most functionals fail to properly account for the effects of London dispersion. Hence, there are many popular post-self-consistent methods to add a dispersion correction to the DFT energy. Until now, the most popular methods have never been compared on equal footing due to not being implemented in the same electronic structure packages. In this work, we performed a large-scale benchmarking study, directly comparing the accuracy of the exchange-hole dipole moment (XDM), D3BJ, D4, TS, MBD, and MBD-NL dispersion models when applied to the recent DES15K database of nearly 15,000 molecular complexes at both expanded and compressed geometries. Our study showed similarly good performance for all dispersion methods (except TS) when applied to neutral complexes. However, they all performed worse for ionic complexes, particularly those involving dications of alkaline earth metals, due to systematic overbinding by the base PBE0 density functional. Investigation of the largest outliers also revealed that only the MBD and MBD-NL methods demonstrate surprising errors for complexes involving alkali metal cations at compressed geometries where they tended to significantly overbind. As we would expect minimal dispersion binding for such complexes, we further investigated the origins of these errors for the potential energy curve of a model cation-π complex. Overall, there is little choice between the XDM, D3BJ, D4, MBD, and MBD-NL dispersion methods for most systems. However, the MBD-based methods are not recommended for complexes involving organic species and alkali or alkaline earth metal cations, for example when modeling Li+ intercalation into graphite.

Many-body dispersion in model systems and the sensitivity of self-consistent screening.

London dispersion is a weak, attractive, intermolecular force that occurs due to interactions between instantaneous dipole moments. While individual dispersion contributions are small, they are the dominating attractive force between nonpolar species and determine many properties of interest. Standard semi-local and hybrid methods in density-functional theory do not account for dispersion contributions, so a correction such as the exchange-hole dipole moment (XDM) or many-body dispersion (MBD) models must be added. Recent literature has discussed the importance of many-body effects on dispersion, and attention has turned to which methods accurately capture them. By studying systems of interacting quantum harmonic oscillators from first principles, we directly compare computed dispersion coefficients and energies from XDM and MBD and also study the influence of changing oscillator frequency. Additionally, the 3-body energy contributions for both XDM, via the Axilrod-Teller-Muto term, and MBD, via a random-phase approximation formalism, are calculated and compared. Connections are made to interactions between noble gas atoms as well as to the methane and benzene dimers and to two layered materials, graphite and MoS2. While XDM and MBD give similar results for large separations, some variants of MBD are found to be susceptible to a polarization catastrophe at short range, and the MBD energy calculation is seen to fail in some chemical systems. Additionally, the self-consistent screening formalism used in MBD is shown to be surprisingly sensitive to the choice of input polarizabilities.

Low thermal expansion of layered electrides predicted by density-functional theory.

Layered electrides are a unique class of materials with anionic electrons bound in interstitial regions between thin, positively charged atomic layers. While density-functional theory is the tool of choice for computational study of electrides, there has to date been no systematic comparison of density functionals or dispersion corrections for their accurate simulation. There has also been no research into the thermomechanical properties of layered electrides, with computational predictions considering only static lattices. In this work, we investigate the thermomechanical properties of five layered electrides using density-functional theory to evaluate the magnitude of thermal effects on their lattice constants and cell volumes. We also assess the accuracy of five popular dispersion corrections with both planewave and numerical atomic orbital calculations.

Understanding the experiences and perspectives of prenatal screening among a diverse cohort.

INTRODUCTION: Rapid advances in prenatal genetic screening technology make it difficult for providers to deliver adequate prenatal counseling. The aim of this study was to understand how prenatal screening educational approaches can meet the needs of patients. METHODS: Qualitative content analysis was conducted on a diverse population who were interviewed to explore their perceived experiences and preferences for prenatal screening educational delivery. RESULTS: Twenty-two women from three US sites were interviewed. Participants were racially/ethnically diverse with 22.7% identifying as Black or African American (n = 5), 40.9% as Hispanic (n = 9), and 4.5% as Pacific Islander (n = 1). Four themes were identified: prenatal screening education, prenatal screening decision-making, return of results, and suggestions for creating a decision aid. Most results were consistent with previous research not targeting a diverse population. DISCUSSION/CONCLUSION: Our results indicate that learning style preferences vary between patients and that current methods are not consistently satisfying patient's desire for understanding, particularly with 'high-risk' results, suggesting that a standardized tool could improve knowledge and decrease decisional conflict. This diverse cohort suggested a list and description of each of the testing options offered, information about each condition being screened for, a timeline for the testing and return of results, costs associated, and non-technical language.

DFT exchange: sharing perspectives on the workhorse of quantum chemistry and materials science.

In this paper, the history, present status, and future of density-functional theory (DFT) is informally reviewed and discussed by 70 workers in the field, including molecular scientists, materials scientists, method developers and practitioners. The format of the paper is that of a roundtable discussion, in which the participants express and exchange views on DFT in the form of 302 individual contributions, formulated as responses to a preset list of 26 questions. Supported by a bibliography of 777 entries, the paper represents a broad snapshot of DFT, anno 2022.

A density-functional benchmark of vibrational free-energy corrections for molecular crystal polymorphism.

Many crystal structure prediction protocols only concern themselves with the electronic energy of molecular crystals. However, vibrational contributions to the free energy (Fvib) can be significant in determining accurate stability rankings for crystal candidates. While force-field studies have been conducted to gauge the magnitude of these free-energy corrections, highly accurate results from quantum mechanical methods, such as density-functional theory (DFT), are desirable. Here, we introduce the PV17 set of 17 polymorphic pairs of organic molecular crystals, for which plane wave DFT is used to calculate the vibrational free energies and free-energy differences (ΔFvib) between each pair. Our DFT results confirm that the vibrational free-energy corrections are small, having a mean value of 1.0 kJ/mol and a maximum value of 2.3 kJ/mol for the PV17 set. Furthermore, we assess the accuracy of a series of lower-cost DFT, semi-empirical, and force-field models for computing ΔFvib that have been proposed in the literature. It is found that calculating Fvib using the Γ-point frequencies does not provide ΔFvib values of sufficiently high quality. In addition, ΔFvib values calculated using various approximate methods have mean absolute errors relative to our converged DFT results of equivalent or larger magnitude than the vibrational free-energy corrections themselves. Thus, we conclude that, in a crystal structure prediction protocol, it is preferable to forego the inclusion of vibrational free-energy corrections than to estimate them with any of the approximate methods considered here.

Evaluating the Implementation of Evidence-based Kidney Nutrition Practice Guidelines: The AUGmeNt Study Protocol.

Evidence-based nutrition practice guidelines (EBNPGs) inform registered dietitian nutritionist (RDN) care for patients with chronic kidney disease grade 5 treated by dialysis; however, there has been little evaluation of best practices for implementing EBNPGs. In this effectiveness-implementation hybrid study with a quasi-experimental design, United States RDNs in hemodialysis clinics will document initial and follow-up nutrition care for patients with chronic kidney disease grade 5 treated by dialysis using the Academy of Nutrition and Dietetics Health Informatics Infrastructure before and after being randomly assigned to a training model: (1) EBNPG knowledge training or (2) EBNPG knowledge training plus an implementation toolkit. The aims of the study include examining congruence of RDN documentation of nutrition care with the EBNPG; describing common RDN-reported EBNPG acceptability, adoption, and adaptation issues; and determining the feasibility of estimating the impact of RDN care on nutrition-related patient outcomes. The AUGmeNt study can inform effective development and implementation of future EBNPGs. Keywords: Chronic kidney diseases; medical nutrition therapy; implementation science; clinical practice guideline; nutrition care process terminology; dietitian.

Using ethnodrama to support parents in sense-making after prenatal or neonatal diagnosis of a child's disabling condition.

BACKGROUND/AIMS: This study describes the process of developing video vignettes to meet the parent-expressed need for balanced, meaningful messages about what life may be like for parents who have a child with a disability. Each vignette teaches a general audience salient concepts derived from a grounded theory of the parental process of Rescuing Hope after a child's diagnosis with a developmental disability. METHODS: Using ethnodrama methodology, we completed a secondary analysis of 21 interviews with parents who learned of their child's diagnosis of Down syndrome. RESULTS: Understanding the grounded theory of Rescuing Hope has the potential to help parents construct meaning and purpose as they adapt to parenting a child with a disability. DISCUSSION: The short dramatic vignettes may be placed across platforms, settings and partnerships, with relevance for teachers, clinicians, family members, caregivers. Designed for wide distribution, video vignettes may reach the people who most need sense-making support.

Bleeding, death, and costs of care during hospitalization for acute pulmonary embolism: Insights from the Saint Luke's Outcomes of Pulmonary Embolism (SLOPE) study.

Limited data exist that comprehensively describe the practical management, in-hospital outcomes, healthcare resource utilization, and rates of post-hospital readmission among patients with submassive and massive pulmonary embolism (PE). Consecutive discharges for acute PE were identified from a single health system over 3 years. Records were audited to confirm presence of acute PE, patient characteristics, disease severity, medical treatment, and PE-related invasive therapies. Rates of in-hospital major bleeding and death, hospital length of stay (LOS), direct costs, and hospital readmission are reported. From January 2016 to December 2018, 371 patients were hospitalized for acute massive or submassive PE. In-hospital major bleeding (12.1%) was common, despite low utilization of systemic thrombolysis (1.8%) or catheter-directed thrombolysis (3.0%). In-hospital death was 10-fold higher among massive PE compared to submassive PE (36.6% vs 3.3%, p < 0.001). Massive PE was more common during hospitalizations not primarily related to venous thromboembolism, including hospitalizations primarily for sepsis or infection (26.8% vs 8.2%, p = 0.001). Overall, the median LOS was 6.0 days (IQR, 3.0-11.0) and the median standardized direct cost of admissions was $10,032 (IQR, $4467-$20,330). Rates of all-cause readmission were relatively high throughout late follow-up but did not differ between PE subgroups. Despite low utilization of thrombolysis, in-hospital bleeding remains a common adverse event during hospitalizations for acute PE. Although massive PE is associated with high risk for in-hospital bleeding and death, those successfully discharged after a massive PE demonstrate similar rates of readmission compared to submassive PE into late follow-up.

Interplay between London Dispersion, Hubbard U, and Metastable States for Uranium Compounds.

High-throughput computational studies of lanthanide and actinide chemistry with density-functional theory are complicated by the need for Hubbard U corrections, which ensure localization of the f-electrons, but can lead to metastable states. This work presents a systematic investigation of the effects of both Hubbard U value and metastable states on the predicted structural and thermodynamic properties of four uranium compounds central to the field of nuclear fuels: UC, UN, UO2, and UCl3. We also assess the impact of the exchange-hole dipole moment (XDM) dispersion correction on the computed properties. Overall, the choice of Hubbard U value and inclusion of a dispersion correction cause larger variations in the computed geometric properties than result from metastable states. The weak dependence of structure optimization on metastable states should simplify future high-throughput calculations on actinides. Conversely, addition of the dispersion correction is found to offset the repulsion introduced by the Hubbard U term and provides greatly improved agreement with experiment for both cell volumes and heats of formation. The XDM dispersion correction is largely invariant to the chosen U value, making it a robust dispersion correction for actinide systems.

Requirements for an accurate dispersion-corrected density functional.

Post-self-consistent dispersion corrections are now the norm when applying density-functional theory to systems where non-covalent interactions play an important role. However, there is a wide range of base functionals and dispersion corrections available from which to choose. In this work, we opine on the most desirable requirements to ensure that both the base functional and dispersion correction, individually, are as accurate as possible for non-bonded repulsion and dispersion attraction. The base functional should be dispersionless, numerically stable, and involve minimal delocalization error. Simultaneously, the dispersion correction should include finite damping, higher-order pairwise dispersion terms, and electronic many-body effects. These criteria are essential for avoiding reliance on error cancellation and obtaining correct results from correct physics.

Assessing clinical education tools for expanded carrier screening.

Expanded carrier screening (ECS) is increasingly offered to a broader population and raises challenges of how to best educate and counsel the volume of screened individuals. For this study, we compared three educational tools (brochure, video and comic) about ECS on knowledge and decision making. A convenience online sample of 151 pregnant women was randomized to one of three groups (Video, n = 42; Comic n = 54; Brochure n = 55). Knowledge scores were significantly higher for the comic group compared to the video or the brochure groups (p < .001). No significant differences in preparation for decision making, decisional conflict, or perceptions of shared decision making were identified between the study groups. This study suggests that a comic about ECS may improve patient attention and retention of information. The use of graphic narratives may enable individuals to better understand medical information in general.

Mediators of Metabolism: An Unconventional Role for NOD1 and NOD2.

In addition to their classical roles as bacterial sensors, NOD1 and NOD2 have been implicated as mediators of metabolic disease. Increased expression of NOD1 and/or NOD2 has been reported in a range of human metabolic diseases, including obesity, diabetes, non-alcoholic fatty liver disease, and metabolic syndrome. Although NOD1 and NOD2 share intracellular signaling pathway components, they are differentially upregulated on a cellular level and have opposing impacts on metabolic disease development in mouse models. These NOD-like receptors may directly mediate signaling downstream of cell stressors, such as endoplasmic reticulum stress and calcium influx, or in response to metabolic signals, such as fatty acids and glucose. Other studies suggest that stimulation of NOD1 or NOD2 by their bacterial ligands can result in inflammation, altered insulin responses, increased reactive oxygen signaling, and mitochondrial dysfunction. The activating stimuli for NOD1 and NOD2 in the context of metabolic disease are controversial and may be a combination of both metabolic and circulating bacterial ligands. In this review, we will summarize the current knowledge of how NOD1 and NOD2 may mediate metabolism in health and disease, as well as highlight areas of future investigation.

Psychometric properties of a brief self-reported health-related quality of life measure (HRQoL-IDD) for persons with intellectual and developmental disabilities.

BACKGROUND: To encourage self-determination and address health disparities among persons with intellectual and developmental disabilities, clinicians and researchers rely on self-reported measures like health-related quality of life (HRQoL). This study evaluated the psychometric properties of a theory-driven self-reported HRQoL measure for adults requiring mild to moderate support related to intellectual and developmental disabilities. METHOD: 224 volunteers completed 42 quality of life items developed with extensive input from persons with intellectual and developmental disabilities, family members/caregivers, and providers. The 5-point Likert scale format with visual images of fluid-filled cups represented the range of responses. RESULTS: Exploratory and Unrestricted Factor Analyses yielded 16 HRQoL items with 4 subscales: Functional Well-Being, Emotional Well-Being, Social Well-Being, and Healthy Decision-making. The HRQoL-IDD explained 62.8% of variance, had satisfactory internal consistency (0.73-0.83), stability of reponses, and reading level (2nd grade, ages 7-8). CONCLUSIONS: The HRQoL-IDD is a promising measure of self-reported HRQoL for use in community-based settings for persons requiring mild to moderate support related to intellectual and developmental disabilities.

The Relative Thermodynamic Stability of Diamond and Graphite.

Recent density-functional theory (DFT) calculations raised the possibility that diamond could be degenerate with graphite at very low temperatures. Through high-accuracy calorimetric experiments closing gaps in available data, we reinvestigate the relative thermodynamic stability of diamond and graphite. For T<400 K, graphite is always more stable than diamond at ambient pressure. At low temperatures, the stability is enthalpically driven, and entropy terms add to the stability at higher temperatures. We also carried out DFT calculations: B86bPBE-25X-XDM//B86bPBE-XDM and PBE0-XDM//PBE-XDM results overlap with the experimental -TΔS results and bracket the experimental values of ΔH and ΔG, displaced by only about 2× the experimental uncertainty. Revised values of the standard thermodynamic functions for diamond are Δf Ho =-2150±150 J mol-1 , Δf So =3.44±0.03 J K-1 mol-1 and Δf Go =-3170±150 J mol-1 .

Potent Inhibition of Mandelate Racemase by Boronic Acids: Boron as a Mimic of a Carbon Acid Center.

Boronic acids have been successfully employed as inhibitors of hydrolytic enzymes. Typically, an enzymatic nucleophile catalyzing hydrolysis adds to the electrophilic boron atom forming a tetrahedral species that mimics the intermediate(s)/transition state(s) for the hydrolysis reaction. We show that para-substituted phenylboronic acids (PBAs) are potent competitive inhibitors of mandelate racemase (MR), an enzyme that catalyzes a 1,1-proton transfer rather than a hydrolysis reaction. The Ki value for PBA was 1.8 ± 0.1 µM, and p-Cl-PBA exhibited the most potent inhibition (Ki = 81 ± 4 nM), exceeding the binding affinity of the substrate by ∼4 orders of magnitude. Isothermal titration calorimetric studies with the wild-type, K166M, and H297N MR variants indicated that, of the two Brønsted acid-base catalysts Lys 166 and His 297, the former made the greater contribution to inhibitor binding. The X-ray crystal structure of the MR·PBA complex revealed the presence of multiple H-bonds between the boronic acid hydroxyl groups and the side chains of active site residues, as well as formation of a His 297 Nε2-B dative bond. The dramatic upfield change in chemical shift of 27.2 ppm in the solution-phase 11B nuclear magnetic resonance spectrum accompanying binding of PBA by MR was consistent with an sp3-hybridized boron, which was also supported by density-functional theory calculations. These unprecedented findings suggest that, beyond substituting boron at carbon centers participating in hydrolysis reactions, substitution of boron at the acidic carbon center of a substrate furnishes a new approach for generating inhibitors of enzymes catalyzing the deprotonation of carbon acid substrates.

Quantum Chemical Methods for Modeling Covalent Modification of Biological Thiols.

Targeted covalent inhibitor drugs require computational methods that go beyond simple molecular-mechanical force fields in order to model the chemical reactions that occur when they bind to their targets. Here, several semiempirical and density-functional theory (DFT) methods are assessed for their ability to describe the potential energy surface and reaction energies of the covalent modification of a thiol by an electrophile. Functionals such as PBE and B3LYP fail to predict a stable enolate intermediate. This is largely due to delocalization error, which spuriously stabilizes the prereaction complex, in which excess electron density is transferred from the thiolate to the electrophile. Functionals with a high-exact exchange component, range-separated DFT functionals, and variationally optimized exact exchange (i.e., the LC-B05minV functional) correct this issue to various degrees. The large gradient behavior of the exchange enhancement factor is also found to significantly affect the results, leading to the improved performance of PBE0. While ωB97X-D and M06-2X were reasonably accurate, no method provided quantitative accuracy for all three electrophiles, making this a very strenuous test of functional performance. Additionally, one drawback of M06-2X was that molecular dynamics (MD) simulations using this functional were only stable if a fine integration grid was used. The low-cost semiempirical methods, PM3, AM1, and PM7, provide a qualitatively correct description of the reaction mechanism, although the energetics is not quantitatively reliable. As a proof of concept, the potential of mean force for the addition of methylthiolate to methylvinyl ketone was calculated using quantum mechanical/molecular mechanical MD in an explicit polarizable aqueous solvent. © 2019 Wiley Periodicals, Inc.