Validity of a Common Measure of Intimate Partner Violence Perpetration: Impact on Study Inference in Trials in Low- and Middle-Income Countries.

Background: In lower-and middle-income countries (LMICs), studies of interventions to reduce intimate partner violence (IPV) perpetration are expanding, yet measurement equivalence of the IPV perpetration construct that is the primary outcome in these investigations has not been established. We assessed the measurement equivalence of physical and sexual IPV perpetration item sets used in recent trials in LMICs and tested the impact of non-invariance on trial inference. Methods: With data from three intervention trials among men (sample size 505-1537 across studies) completed in 2019, we calculated tetrachoric correlations among items and used multiple-group confirmatory factor analysis to assess invariance across arms and over time. We also assessed treatment effects adjusting for covariate imbalance and using inverse probability to treatment weights to assess concordance of invariant measures with published results, where warranted. Findings: The average correlation among items measuring IPV perpetration was high and increased by 0.03 to 0.15 for physical IPV and 0.07 to 0.17 for sexual IPV over time with several items in two studies showing correlations ≥ 0.85 at endline. Increases in the degree of correlation for physical IPV were concentrated in the treatment arm in two of the studies. The increase in correlation in sexual IPV differed by arm across studies. Across all studies, a correlated two-factor solution was the best fitting model according to the EFAs and CFAs. One study demonstrated measurement invariance across arms and over time. In two of the studies, longitudinal measurement non-invariance was detected in the intervention arms. In post hoc testing, one study attained invariance with a one-factor model and study inference was concordant with published findings. The other study did not attain even partial invariance. Conclusion: Common measures of physical and sexual IPV perpetration cannot be used validly for comparisons across treatment versus control groups over time without further refinement. The study highlights the need for an expanded item set, content validity assessments, further measurement invariance testing, and then consistent use of the item sets in future intervention trials to ensure valid inferences regarding the effectiveness of IPV perpetration prevention interventions within and across trials.

Effect of [n]-Helicene Length on Crystal Packing.

Chiral π-conjugated organic molecules hold potential for emerging technologies as they are capable of introducing novel functionalities into electronic devices owing to their strong chiroptical properties. However, capitalizing on chiral molecules for electronic devices is reliant on their molecular packing-a factor that impacts their charge-transport properties. The solid-state behavior of molecules is sensitive to subtle differences in molecular interactions, chirality, and shape, but these relationships are not fully understood. Here, we employ crystal structure prediction (CSP) as a tool to probe the lattice-energy landscape for a family of chiral organic molecules: [n]helicenes, where n ranges from 3 to 12. Our results show excellent agreement between the CSP landscapes and experimentally reported structures. By analyzing the packing motifs within the polymorph landscapes, we begin to develop an understanding of how helicene length affects the shape and π-π stacking interactions seen in the polymorphs. Furthermore, we propose how helicene length can be used as a tool to design new functional organic electronics.

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.

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.

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.

Measurement invariance of the Center for Epidemiologic Studies Scale-Depression within and across six diverse intervention trials.

Depression, a major contributor to the global burden of disease, is an outcome of interest in clinical trials. Researchers and clinicians note that depression often presents differently across cultures, posing challenges in the accurate measurement of depressive symptoms across populations. A commonly used self-administered screening tool to measure depressive symptoms, the Center for Epidemiologic Studies Scale-Depression (CES-D), has been translated into dozens of languages and used in thousands of studies, yet gaps remain in our understanding of its factor structure and invariance across studies and over time in the context of interventions. In this secondary analysis, we sampled six recent trials from lower- and middle-income countries to (a) establish the factor structure of the CES-D, (b) assess measurement invariance of the CES-D across treatment versus control arms and over time, (c) examine cross-study invariance, and (d) identify items that may be driving potential noninvariance. We performed exploratory/confirmatory factor analysis to establish the factor structure of the CES-D within each trial and used multiple group confirmatory analysis to assess within-study cross-arm/cross-time and cross-study invariance. After removal of positive affect items, a unidimensional model performed equivalently over time and across arms within trials, but exhibited noninvariance across trials, supporting prior literature describing differences in factor structure of the scale across populations. While our findings suggest that the CES-D without positive affect items is a valid measure of depressive symptoms within trials in our sample, caution is warranted in interpreting the findings of meta-analyses and multisite/multicountry studies using the CES-D as an outcome measure. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Periodic trends in the structural, electronic, and transport properties of electrenes.

Two-dimensional layered electrides are a class of atomically thin materials in which the anion is an excess electron rather than a negatively charged ion. These excess electrons form delocalized sheets of charge surrounding each layer of the material. A well-known example is Ca2N; its identification and characterization has triggered an avalanche of studies aimed at broadening applications of electrides. Ca2N is only one member of the M2X family of materials, with M being an alkaline-earth metal and X belonging to the pnictogen group, which can be exfoliated to form single- or few-layer electrenes. The goal of this study is to systematically investigate the monolayer and bilayer properties for this family of materials. Density-functional calculations reveal linear relationships between surface and interstitial charges, work functions, exfoliation energies, and Ewald energies. Using the Landauer formalism, informed by rigorous electron-phonon scattering calculations, we also investigate the electronic transport characteristics of the monolayer and bilayer electrenes. Our findings indicate that the nitrogen-based electrenes (Ca2N, Sr2N, and Ba2N) are more conductive than their counterparts involving heavier pnictogens. The results of this study highlight underlying periodic trends in electrene properties that can help identify which materials would be best suited for particular applications.

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.

Quantitative matching of crystal structures to experimental powder diffractograms.

The identification and classification of crystal structures is fundamental in materials science, as the crystal structure is an inherent factor of what gives solid materials their properties. Being able to identify the same crystallographic form from unique origins (e.g. different temperatures, pressures, or in silico-generated) is a complex challenge. While our previous work has focused on comparison of simulated powder diffractograms from known crystal structures, herein is presented the variable-cell experimental powder difference (VC-xPWDF) method to match collected powder diffractograms of unknown polymorphs to both experimental crystal structures from the Cambridge Structural Database and in silico-generated structures from the Control and Prediction of the Organic Solid State database. The VC-xPWDF method is shown to correctly identify the most similar crystal structure to both moderate and "low" quality experimental powder diffractograms for a set of 7 representative organic compounds. Features of the powder diffractograms that are more challenging for the VC-xPWDF method are discussed (i.e. preferred orientation), and comparison with the FIDEL method showcases the advantage of VC-xPWDF provided the experimental powder diffractogram can be indexed. The VC-xPWDF method should allow rapid identification of new polymorphs from solid-form screening studies, without requiring single-crystal analysis.

XDM-corrected hybrid DFT with numerical atomic orbitals predicts molecular crystal lattice energies with unprecedented accuracy.

Molecular crystals are important for many applications, including energetic materials, organic semiconductors, and the development and commercialization of pharmaceuticals. The exchange-hole dipole moment (XDM) dispersion model has shown good performance in the calculation of relative and absolute lattice energies of molecular crystals, although it has traditionally been applied in combination with plane-wave/pseudopotential approaches. This has limited XDM to use with semilocal functional approximations, which suffer from delocalization error and poor quality conformational energies, and to systems with a few hundreds of atoms at most due to unfavorable scaling. In this work, we combine XDM with numerical atomic orbitals, which enable the efficient use of XDM-corrected hybrid functionals for molecular crystals. We test the new XDM-corrected functionals for their ability to predict the lattice energies of molecular crystals for the X23 set and 13 ice phases, the latter being a particularly stringent test. A composite approach using a XDM-corrected, 25% hybrid functional based on B86bPBE achieves a mean absolute error of 0.48 kcal mol-1 per molecule for the X23 set and 0.19 kcal mol-1 for the total lattice energies of the ice phases, compared to recent diffusion Monte-Carlo data. These results make the new XDM-corrected hybrids not only far more computationally efficient than previous XDM implementations, but also the most accurate density-functional methods for molecular crystal lattice energies to date.

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.

Controlling anisotropic properties by manipulating the orientation of chiral small molecules.

Chiral π-conjugated molecules bring new functionality to technological applications and represent an exciting, rapidly expanding area of research. Their functional properties, such as the absorption and emission of circularly polarized light or the transport of spin-polarized electrons, are highly anisotropic. As a result, the orientation of chiral molecules critically determines the functionality and efficiency of chiral devices. Here we present a strategy to control the orientation of a small chiral molecule (2,2'-dicyano[6]helicene) by the use of organic and inorganic templating layers. Such templating layers can either force 2,2'-dicyano[6]helicene to adopt a face-on orientation and self-assemble into upright supramolecular columns oriented with their helical axis perpendicular to the substrate, or an edge-on orientation with parallel-lying supramolecular columns. Through such control, we show that low- and high-energy chiroptical responses can be independently 'turned on' or 'turned off'. The templating methodologies described here provide a simple way to engineer orientational control and, by association, anisotropic functional properties of chiral molecular systems for a range of emerging technologies.

Occurrence and accumulation of heavy metals in algal turf particulates and sediments on coral reefs.

Algal turfs form a critical interface on coral reefs that interacts with several key ecosystem processes. While we know these turfs have a remarkable propensity to accumulate sediments, which can have a range of ecosystem impacts, their role as sinks for heavy metals remains largely unexamined. Here we quantified the concentration of 15 metals in algal turf sediments from Lizard Island and Orpheus Island on the Great Barrier Reef, and specifically explored how the loads of arsenic, cobalt, iron and lead were related to turf length. Metal composition differed markedly between the two islands, with the composition at Orpheus Island suggesting closer links to terrestrial sediment sources. Furthermore, metal loads increased significantly with turf length, suggesting that longer turfs can accumulate these pollutants on reefs. Given that algal turfs are a crucial component of herbivorous/detritivorous trophic pathways, this could represent a key juncture at which these metals enter food chains.

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.

Health care access and contraceptive use among adult women in the United States in 2017.

OBJECTIVE: To examine the relationship between insurance status and contraceptive use, with health care access as a mediating variable. STUDY DESIGN: This study uses data from the 2017 Behavioral Risk Factor Surveillance Survey to determine whether having a personal healthcare provider and experiencing cost as a barrier to care mediate the relationship between health insurance status and contraceptive use among women at risk of unintended pregnancy. Contraceptive use is measured 3 ways: as a binary variable (use vs non-use), by prescription status, and by tiered effectiveness. RESULTS: Having insurance increases the odds of using all categories of contraception. Having a personal health care provider mediates this relationship, with having a personal health care provider increasing the odds of using any contraceptive, using a prescription method, and using a tier I or tier II method. Experiencing cost as a barrier to care is not associated with contraceptive use in weighted multivariable models but does mediate the relationship between having insurance and using tier-II methods. CONCLUSIONS: These findings suggest that having health insurance and an ongoing relationship with a health care provider are key to ensuring consistent access to the full range of contraceptive options. This is particularly relevant in light of the ongoing policy debates regarding laws intended to increase health insurance access and decrease barriers to contraceptive use. IMPLICATIONS: This paper updates and extends previous findings to show that the relationship between healthcare access and contraceptive use persists after the implementation of the Affordable Care Act and that having a personal provider partially explains this relationship.

Theoretical modeling of structural superlubricity in rotated bilayer graphene, hexagonal boron nitride, molybdenum disulfide, and blue phosphorene.

The superior lubrication capabilities of two-dimensional crystalline materials such as graphene, hexagonal boron nitride (h-BN), and molybdenum disulfide (MoS2) have been well known for many years. It is generally accepted that structural superlubricity in these materials is due to misalignment of the surfaces in contact, known as incommensurability. In this work, we present a detailed study of structural superlubricity in bilayer graphene, h-BN, MoS2, and the novel material blue phosphorene (b-P) using dispersion-corrected density-functional theory with periodic boundary conditions. Potential energy surfaces for interlayer sliding were computed for the standard (1 × 1) cell and three rotated, Moiré unit cells for each material. The energy barriers to form the rotated structures remain higher than the minimum-energy sliding barriers for the (1 × 1) cells. However, if the rotational barriers can be overcome, nearly barrierless interlayer sliding is observed in the rotated cells for all four materials. This is the first density-functional investigation of friction using rotated, Moiré cells, and the first prediction of structural superlubricty for b-P.

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.

Directed Ortho and Remote Metalation of Naphthalene 1,8-Diamide: Complementing SEAr Reactivity for the Synthesis of Substituted Naphthalenes.

Mono- and dianion species of 1,8-naphthalene diamide 2 were generated under sec-BuLi/TMEDA conditions and trapped with a variety of electrophiles to give 2- and 2,7- substituted products 3 and 4. Using Suzuki-Miyaura cross-coupling, mono- and di-iodinated products were converted into the corresponding 2-aryl (5) and 2,7-diaryl (6) products, respectively. The amide-amide rotation barrier of 2 was established by VT NMR, and the structure of fluorenone structure 9, obtained by remote metalation, was secured.

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.

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 .