Insights into the structure and dynamics of K+ ions at the muscovite-water interface from machine learning potential simulations.

The surfaces of many minerals are covered by naturally occurring cations that become partially hydrated and can be replaced by hydronium or other cations when the surface is exposed to water or an aqueous solution. These ion exchange processes are relevant to various chemical and transport phenomena, yet elucidating their microscopic details is challenging for both experiments and simulations. In this work, we make a first step in this direction by investigating the behavior of the native K+ ions at the interface between neat water and the muscovite mica (001) surface with ab-initio-based machine learning molecular dynamics and enhanced sampling simulations. Our results show that the desorption of the surface K+ ions in pure ion-free water has a significant free energy barrier irrespective of their local surface arrangement. In contrast, facile K+ diffusion between mica's ditrigonal cavities characterized by different Al/Si orderings is observed. This behavior suggests that the K+ ions may favor a dynamic disordered surface arrangement rather than complete desorption when exposed to deionized water.

Ablation Versus Antiarrhythmic Drugs as First-Line Therapy for Treatment-Naive Atrial Fibrillation: A Systematic Review and Meta-Analysis.

Evidence on the relative safety and efficacy of atrial fibrillation catheter ablation and antiarrhythmic drugs (AADs) as the first-line therapy for patients with treatment-naive atrial fibrillation (AF) remains disputed. Digital databases were queried to identify relevant randomized controlled trials. The incidence of recurrent AF, major adverse cardiovascular events, and its components (all-cause death, nonfatal stroke, and bleeding) were compared using the DerSimonian and Laird method under the random-effects model to calculate pooled unadjusted risk ratio (RR) with 95% confidence intervals (CIs). A total of 6 randomized controlled trials consisting of 1,120 patients (574 ablation and 549 AADs) were included in the final analysis. Over a median follow-up of 1 year, the risk of any AF recurrence (RR 0.54, 95% CI 0.39 to 0.75) was significantly lower in patients receiving ablation than in patients receiving AADs. However, there was similar risk of major adverse cardiovascular events (RR 2.65, 95% CI 0.61 to 11.46), trial-defined composite end point of adverse events (RR 0.71, 95% CI 0.28 to 1.80), stroke (RR 2.42, 95% CI 0.22 to 26.51), all-cause mortality (RR 1.98, 95% CI 0.28 to 13.90), and procedure/medication failure (RR 2.65, 95% CI 0.61 to 11.46) with both therapies. In conclusion, in patients presenting with treatment-naive AF, ablation as a first-line therapy lowers the risk of AF recurrence with no associated increase in major adverse events, stroke, and mortality compared with AADs.

Acid-Base Chemistry of a Model IrO2 Catalytic Interface.

Iridium oxide (IrO2) is one of the most efficient catalytic materials for the oxygen evolution reaction (OER), yet the atomic scale structure of its aqueous interface is largely unknown. Herein, the hydration structure, proton transfer mechanisms, and acid-base properties of the rutile IrO2(110)-water interface are investigated using ab initio based deep neural-network potentials and enhanced sampling simulations. The proton affinities of the different surface sites are characterized by calculating their acid dissociation constants, which yield a point of zero charge in agreement with experiments. A large fraction (≈80%) of adsorbed water dissociation is observed, together with a short lifetime (≈0.5 ns) of the resulting terminal hydroxy groups, due to rapid proton exchanges between adsorbed H2O and adjacent OH species. This rapid surface proton transfer supports the suggestion that the rate-determining step in the OER may not involve proton transfer across the double layer into solution, as indicated by recent experiments.

Modeling the Solvation and Acidity of Carboxylic Acids Using an Ab Initio Deep Neural Network Potential.

Formic and acetic acid constitute the simplest of carboxylic acids, yet they exhibit fascinating chemistry in the condensed phase such as proton transfer and dimerization. The go-to method of choice for modeling these rare events have been accurate but expensive ab initio molecular dynamics simulations. In this study, we present a deep neural network potential trained using accurate ab initio data that can be used in tandem with enhanced-sampling methods to perform an efficient exploration of the free-energy surface of aqueous solutions of weak carboxylic acids. In particular, we show that our model captures proton dissociation and provides a good estimate of the pKa, as well as the dimerization of formic and acetic acid. This provides a suitable starting point for applications in different research areas where computational efficiency coupled with the accuracy of ab initio methods is required.

2D speckle tracking: a diagnostic and prognostic tool of paramount importance.

OBJECTIVE: We aimed to conduct a review of the literature relevant to cardiac imaging techniques and summarize the use of different non-invasive imaging modalities in the assessment of ventricular size, function, and mechanics. The current review emphasizes the benefits of speckle tracking imaging (STI), highlighting its use in demonstrating myocardial strain. This robust technique is a recent addition to the existing imaging techniques that are used to assess the myocardium. In terms of effectively determining the left ventricle ejection fraction, it is a comparable technique to cardiac magnetic resonance. The use of STI method for image acquisition relies on semiautomatic identification of the border and deformation of the region of interest, and is also independent of the angle of insonation, thus it increases the inter-and intra-observer reproducibility in contrast to the conventional tissue doppler imaging. MATERIALS AND METHODS: The databases of PubMed, Scopus, and Embase were thoroughly searched for the following keywords: 2- dimensional/ two-dimensional/ 2-D, speckle/strain tracking, systolic dysfunction, and heart failure. The studies selected described image acquisition techniques and the application of this imaging modality in various clinical settings. The selected journal articles were perused to provide the best possible analysis of STI. RESULTS: Our comparative analysis demonstrated that the STI, when compared with the conventional echocardiography, is a more sensitive image acquiring technique for detecting subclinical myocardial dysfunction. Based on the analysis it can be stated that the STI can provide valuable information on both regional and global myocardial function, and it can also quantify cardiac synchronicity and rotation. Additionally, it serves as a better prognostic indicator. CONCLUSIONS: The change in longitudinal strain can serve as an early marker of the left ventricular systolic dysfunction, and therefore, monitoring via STI has both diagnostic and prognostic value in heart failure, ischemic heart disease, valvulopathies, chemotherapy-induced cardiotoxicity, and cardiac resynchronization therapy. Despite the lack of standardization, the method is also effective in assessing the right ventricle and left atrial function and arterial rigidity.

Surgical management of the scimitar syndrome.

BACKGROUND AND AIM: We sought to address the varied anatomical details, the diagnostic challenges, associated cardiopulmonary anomalies, the techniques, and outcomes of management, including re-interventions of scimitar syndrome. METHODS: A total of 92 published investigations of scimitar syndrome were reviewed. Diagnostic information was provided by clinical presentations, radiographic findings, transthoracic and transesophageal echocardiography, computed-tomographic angiography, magnetic resonance imaging, angiocardiography, and ventilation/perfusion scans. These investigations served to elucidate the origin, course, and termination of the scimitar vein, the intracardiac anatomy, the presence of associated defects, and the patterns of any accompanying pulmonary lesions prior to surgical intervention. RESULTS: Of the patients described, up to four-fifths presented during infancy, with cardiac failure, increased pulmonary flow, and pulmonary hypertension. Associated cardiac and extracardiac defects, particularly hypoplasia of the right lung, are present in up to three-quarters of cases. Overall operative mortality has been cited between 4.8% and 5.9%. Mortality was highest in patients with preoperative pulmonary hypertension, and those undergoing surgery in infancy. Despite timely surgical intervention, post-repair obstruction of the scimitar vein, intra-atrial baffle obstruction, or stenosis of the inferior caval vein were reported in up to two-thirds of cases. The venous obstruction could not be related to any particular surgical technique. On long term follow-up, one sixth of patients reported persistent dyspnoea and recurrent respiratory infections. CONCLUSIONS: Any infants presenting with heart failure, right-sided heart, and hypoplastic right lung should be evaluated to exclude the syndrome. An increased appreciation of variables will contribute to improved surgical management.

Surface stability of perovskite oxides under OER operating conditions: a first principles approach.

The activity-stability conundrum has long been the Achilles' heel in the design of catalysts, in particular, for electrochemical reactions such as water splitting. Here, we use ab initio thermodynamics to delineate the surface stoichiometry of a group of perovskite oxides with different activities towards the oxygen evolution reaction (OER), in order to get a measure of their stability under OER operating conditions. In particular, we compare the surface stability of SrIrO3, SrRuO3 and SrTiO3, establishing atomistic insights into the stability and dissolution of these oxide surfaces.

Accuracy of Reporting Primary Care Specialty Status in Medical Research.

INTRODUCTION: Family physicians (FPs) are specialty trained and certified and provide most primary care (PC) services in the United States. General practitioners (GPs), a separate group without specialty PC training, are commonly confused with FPs despite differences in demographic characteristics, professional qualifications, and clinical services. Our study documents how often research in major medical journals distinguishes between these 2 groups or combines GPs and FPs together. METHODS: We selected 23 US journals on impact factor and relevance to PC. Using a MEDLINE search, we identified all reports published in 2016 through 2017 that met inclusion criteria: original research; done in United States; studying FPs, GPs, and/or PC physicians. Two researchers reviewed each article to determine inclusion and whether it lumped or split FPs and GPs. RESULTS: Search retrieved 409 total studies, with 88 (21.5%) meeting inclusion criteria. Among these, 35 (39.8%) included FPs only, leaving 53 (60.2%) that also included GPs. Among these studies, only 3 (5.7%) separated GPs from FPs. Another 21 (39.6%) combined GPs and FPs together. In 29 (54.7%), the classification of GPs, FPs and others was not described. CONCLUSIONS: Most PC research reports combine GPs and FPs into a single group, masking differences between these distinct groups. Most research reports fail to explain how they classify PC clinicians. Research reports need to improve classification of FPs and PC clinicians.

Enhancing Oxygen Exchange Activity by Tailoring Perovskite Surfaces.

A detailed understanding of the effects of surface chemical and geometric composition is essential for understanding the electrochemical performance of the perovskite (ABO3) oxides commonly used as electrocatalysts in the cathodes of ceramic fuel cells. Herein, we report how the addition of submonolayer quantities of A- and B-site cations affects the rate of the oxygen reduction reaction (ORR) of Sr-doped LaFeO3 (LSF), LaMnO3 (LSM), and LaCoO3 (LSCo). Density functional theory calculations were performed to determine the stability of different active sites on a collection of surfaces. With LSF and LSM, rates for the ORR are significantly higher on the A-site terminated surface, while surface termination is less important for LSCo. Our findings highlight the importance of tailoring the surface termination of the perovskite to obtain its ultimate ORR performance.

Widom line, dynamical crossover, and percolation transition of supercritical oxygen via molecular dynamics simulations.

Supercritical oxygen, a cryogenic fluid, is widely used as an oxidizer in jet propulsion systems and is therefore of paramount importance in gaining physical insights into processes such as transcritical and supercritical vaporization. It is well established in the scientific literature that the supercritical state is not homogeneous but, in fact, can be demarcated into regions with liquid-like and vapor-like properties, separated by the "Widom line." In this study, we identified the Widom line for oxygen, constituted by the loci of the extrema of thermodynamic response functions (heat capacity, volumetric thermal expansion coefficient, and isothermal compressibility) in the supercritical region, via atomistic molecular dynamics simulations. We found that the Widom lines derived from these response functions all coincide near the critical point until about 25 bars and 15-20 K, beyond which the isothermal compressibility line begins to deviate. We also obtained the crossover from liquid-like to vapor-like behavior of the translational diffusion coefficient, shear viscosity, and rotational relaxation time of supercritical oxygen. While the crossover of the translational diffusion coefficient and shear viscosity coincided with the Widom lines, the rotational relaxation time showed a crossover that was largely independent of the Widom line. Further, we characterized the clustering behavior and percolation transition of supercritical oxygen molecules, identified the percolation threshold based on the fractal dimension of the largest cluster and the probability of finding a cluster that spans the system in all three dimensions, and found that the locus of the percolation threshold also coincided with the isothermal compressibility Widom line. It is therefore clear that supercritical oxygen is far more complex than originally perceived and that the Widom line, dynamical crossovers, and percolation transitions serve as useful routes to better our understanding of the supercritical state.

Correlation of salivary immunoglobulin A against lipopolysaccharide of Porphyromonas gingivalis with clinical periodontal parameters.

BACKGROUND: A major challenge in clinical periodontics is to find a reliable molecular marker of periodontal tissue destruction. AIM: The aim of the present study was to assess, whether any correlation exists between salivary immunoglobulin A (IgA) level against lipopolysaccharide of Porphyromonas gingivalis and clinical periodontal parameters (probing depth and clinical attachment loss). MATERIALS AND METHODS: Totally, 30 patients with chronic periodontitis were included for the study based on clinical examination. Unstimulated saliva was collected from each study subject. Probing depth and clinical attachment loss were recorded in all selected subjects using University of North Carolina-15 periodontal probe. Extraction and purification of lipopolysaccharide were done from the standard strain of P. gingivalis (ATCC 33277). Enzyme linked immunosorbent assay (ELISA) was used to detect the level of IgA antibodies against lipopolysaccharide of P. gingivalis in the saliva of each subject by coating wells of ELISA kit with extracted lipopolysaccharide antigen. STATISTICAL ANALYSIS: The correlation between salivary IgA and clinical periodontal parameters was checked using Karl Pearson's correlation coefficient method and regression analysis. RESULTS: The significant correlation was observed between salivary IgA level and clinical periodontal parameters in chronic periodontitis patients. CONCLUSION: A significant strong correlation was observed between salivary IgA against lipopolysaccharide of P. gingivalis and clinical periodontal parameters which suggest that salivary IgA level against lipopolysaccharide of P. gingivalis can be used to predict the severity of periodontal destruction in chronic periodontitis patients.

A rare case report of Patellar Osteochondroma.

INTRODUCTION: Osteochondroma (OC) is the most common benign tumor of the skeleton. However, patellar OC is very rare. Only five case reports have been published yet and only 1 after the year 1972. OCs grow during childhood through adolescence, but usually growing ends when the epiphyseal plates close. In an adult, the growth of an OC suggests the diagnosis of malignant transformation to a chondrosarcoma. However, enlargement of a patellar OC reported as benign after skeletal maturity is present in literature. CASE REPORT: We report the clinical and radiologic findings of a patellar OC in a 50-year-old female, with a 3-year progression of swelling, not painful, well-defined margins, normal skin, and no neurovascular deficits or functional impairment. The tumor was surgically resected, and histopathological examination did not show malignancy. After 2 years of follow-up, the patient has no complaints and no signs of recurrence. CONCLUSION: Patellar OCsare extremely rare with only a few reports published. It should be kept in mind that benign OCs can show symptomatic growth in skeletally mature patients without malignant transformation.

Stainless steel crowns reuse and decontamination techniques: a survey among Indian pediatric dentists.

OBJECTIVE: To determine the pattern and extent of stainless steel crown (SSC) reuse following try-in and the methods employed for their decontamination among Indian pediatric dentists. STUDY DESIGN: Questionnaires were delivered personally to 100 pediatric dentists selected randomly across India. Questionnaire was divided into three subsections. The first section assessed demographics to determine the sample population characteristics. The second section dealt with the pattern of SSCs use and reuse following size determination. The third section inquired into general cross infection control procedures including cleaning, sterilization, and training to assess the general level of compliance. Data analysis involved descriptive analysis using SPSS 16.0 software. RESULTS: The majority of respondents (98.92%) routinely reused the crowns after they had been tried in the patient. Only one respondent (1.08%) discarded the crowns after try-in. Autoclave (25%) was the most common method employed for the decontamination of tried-in SSCs among the respondents. CONCLUSION: The majority of the participating pediatric dentists are reusing SSCs following try-in during crown selection. However, great diversity exists in the methods employed for the decontamination of the same. This demands for more research to provide guidelines into the most effective method of decontamination.