Dynamic Correlation Analysis between Stress-Strain Curve and Polymer Film Structure Using Persistent Homology.

Coarse-grained molecular dynamics (CG-MD) simulations and subsequent persistent homology (PH) analysis were performed to correlate the structure and stress-strain behavior of polymer films. During uniaxial tensile MD simulations, the first principal component of the persistence diagram obtained by principal component analysis (PCA) was in good agreement with the stress-strain curve. This indicates that PH + PCA can identify critical ring structures relevant to the dynamic changes in MD simulations without requiring any prior knowledge.

Comparison of Early Postoperative Stress Distribution around Short and Tapered Wedge Stems in Femurs with Different Femoral Marrow Cavity Geometries Using Finite Element Analysis.

Backgroud: In total hip arthroplasty (THA), the ideal stem length remains uncertain; different stem lengths are used in different cases or institutions. We aimed to compare the stress distributions of cementless tapered wedges and short stems in femurs with different femoral marrow geometries and determine the appropriate fit.

Methods: Finite element models were created and analyzed using HyperMesh and LS-DYNA R11.

Validation of a New Liquid Asymmetric-Electrode Plasma Optical Emission Spectroscopy (LAEP-OES) Method for Measurement of Total Mercury in Tuna.

Background: Mercury intake is caused by eating seafood, such as tuna and other predatory fish species. To reduce the health risks of mercury intake, it is necessary to continuously measure and monitor mercury concentrations at fish farms and markets. We have developed a compact system that can detect multiple heavy metals by liquid asymmetric-electrode plasma optical emission spectroscopy (LAEP-OES).

Predicting long-term trends in physical properties from short-term molecular dynamics simulations using long short-term memory.

This study proposes a novel long short-term memory (LSTM)-based model for predicting future physical properties based on partial data of molecular dynamics (MD) simulation. It extracts latent vectors from atomic coordinates of MD simulations using graph convolutional network, utilizes LSTM to learn temporal trends in latent vectors and make one-step-ahead predictions of physical properties through fully connected layers. Validating with MD simulations of Ni solid-liquid systems, the model achieved accurate one-step-ahead prediction for time variation of the potential energy during solidification and melting processes using residual connections.

Synthesis of 5-Amino-3(2)-furanones via -Methylation/Intramolecular Cyclization of γ-Sulfanylamides.

The -methylation/intramolecular cyclization of γ-sulfanylamide is depicted. Different methylating reagents were successfully employed for -methylation, depending on the substituent pattern of the amide in the starting γ-sulfanylamides; trimethyloxonium tetrafluoroborate was used for -aryl substituted γ-sulfanylamides, and the combination of methyl iodide and silver(I) tetrafluoroborate was used for -alkyl substituted γ-sulfanylamides. When the resulting sulfonium salt was treated with DBU, it smoothly underwent intramolecular cyclization to produce a series of -aryl, -alkyl, -dialkyl or -alkyl--aryl substituted 5-amino-3(2)-furanones in 55%-quantitative yields.

COVID-19 with Suspected Secondary Pyogenic Arthritis of the Hip: A Case Report and Literature Review.

Introduction: COVID-19 may be associated with orthopedic symptoms, including myalgia and joint pain. There are reports of reactive arthritis and acute arthritis diagnosed after COVID-19; however, COVID-19-associated pyogenic arthritis has not been reported.

Case Report: We treated a young woman with secondary pyogenic hip arthritis that started after COVID-19.

Two Healthy Elderly Females with Contemporaneous Subchondral Insufficiency Fractures of Bilateral Femoral Heads: A Case Report.

Introduction: Unilateral subchondral insufficiency fractures (SIF) of the femoral head have been reported in many cases; however, bilateral cases occurring simultaneously are very rare.

Case Report: We report two cases of relatively active elderly females (aged 73 and 67 years), in which bilateral hip pain appeared simultaneously without any specific triggers. There were no notable lifestyle or medication histories.

Molecular Dynamics Simulation of Adhesion of Additive Molecules in Paint Materials toward Enhancement of Anticorrosion Performance.

Adsorption energies of additive molecules in paint materials on the iron oxide substrate are investigated by molecular dynamics (MD) simulations to find the key feature of adhesion, which is one of the indispensable elements for the corrosion resistance of coated materials. Both edge-on and face-on adsorptions are observed for most additive molecules such as phenylsuccinic acid and benzoic acid. On the other hand, only the edge-on adsorption is observed for the specific molecule having a benzothiazole ring due to the effect of steric conformation.

Predicting materials properties with generative models: applying generative adversarial networks for heat flux generation.

In the realm of materials science, the integration of machine learning techniques has ushered in a transformative era. This study delves into the innovative application of generative adversarial networks (GANs) for generating heat flux data, a pivotal step in predicting lattice thermal conductivity within metallic materials. Leveraging GANs, this research explores the generation of meaningful heat flux data, which has a high degree of similarity with that calculated by molecular dynamics simulations.

Femoral Bowing Increases Early Postoperative Stress around the Femoral Stem in Humans: A Finite Element Analysis.

Background: This study aimed to clarify the characteristics of stress distribution caused by the placement of tapered wedge stems in bowed femurs compared with that in normal femurs and the effect of varus stem placement.

Methods: Models with normal and enhanced bowing were created from the right-side computed tomography data of a 17-year-old woman with the least bowing among 40 participants who underwent anterior cruciate ligament reconstruction or operative treatment for trauma in our hospital between January 2017 and May 2018. Finite element analysis was performed, assuming the tapered wedge stem was placed in the neutral and varus positions.

Relationship between perceived and structural leg length discrepancies of patients with hip osteoarthritis dysplasia.

Background: Only few studies have been conducted on leg length discrepancy (LLD) in patients with hip osteoarthritis (OA). This study aimed to examine the relationship between perceived LLD (pLLD) and structural LLD (sLLD) in patients with advanced OA and to determine the factors influencing both LLDs. This retrospective study aimed to answer the following questions: (1) are older adults less likely to perceive LLD than younger adults? (2) is there a relationship between pLLD and sLLD? and (3) is pLLD associated with patient satisfaction?

Hypothesis: We hypothesized that older adults are less likely to perceive LLD than younger adults.

Influence of femoral bowing on stress distribution of the proximal femur: a three-dimensional finite element analysis.

Background: Whether femoral bowing or its direction has a mechanical effect on the proximal femur is unclear. This study aimed to define the changes in stress distribution in the proximal femur associated with femoral bowing using finite element analysis.

Methods: We created four femoral models: original, entire lateral bowing, entire anterior bowing, and the middle of both (50% anterolateral bowing) from computed tomography data of women with standard bowing.

Free energy surface of initial cap formation in carbon nanotube growth.

Initial cap formation is an important process of carbon nanotube (CNT) growth where a hexagonal carbon network is lifted off from the catalyst surface. In this study, free energy surface (FES) of initial cap formation in the CNT growth is investigated by metadynamics simulation. A two-dimensional collective variable (CV) space is newly developed to examine the complicated formation process of the cap structure, which consists of the formation of a hexagonal carbon network and lift-off of the network from the catalyst surface.

Ultrastrong underwater adhesion on diverse substrates using non-canonical phenolic groups.

Robust underwater adhesion is challenging because a hydration layer impedes the interaction between substrates and adhesives. Phenolic adhesives inspired by marine creatures such as mussels were extensively studied, but these adhesives have not reached the adhesion strength and substrate diversity of Man-made dry adhesives. Here, we report a class of ultrastrong underwater adhesives with molecular phenolic designs extending beyond what nature has produced.

Fast-Decoding Algorithm for Electrode Processes at Electrified Interfaces by Mean-Field Kinetic Model and Bayesian Data Assimilation: An Active-Data-Mining Approach for the Efficient Search and Discovery of Electrocatalysts.

The microscopic origins of the activity and selectivity of electrocatalysts has been a long-lasting enigma since the 19th century. By applying an active-data-mining approach, employing a mean-field kinetic model and a statistical approach of Bayesian data assimilation, we demonstrate here a fast decoding to extract key properties in the kinetics of complicated electrode processes from current-potential profiles in experimental and literary data. As the proof-of-concept, kinetic parameters on the four-electron oxygen reduction reaction in the 0.

Non-classical nucleation in vapor-liquid-solid growth of monolayer WS revealed by in-situ monitoring chemical vapor deposition.

The very early nucleation stage of a transition metal dichalcogenide (TMD) was directly observed with in-situ monitoring of chemical vapor deposition and automated image analysis. Unique nucleation dynamics, such as very large critical nuclei and slow to rapid growth transitions, were observed during the vapor-liquid-solid (VLS) growth of monolayer tungsten disulfide (WS). This can be explained by two-step nucleation, also known as non-classical nucleation, in which metastable clusters are formed through the aggregation of droplets.

Bayesian Data Assimilation of Temperature Dependence of Solid-Liquid Interfacial Properties of Nickel.

Temperature dependence of solid-liquid interfacial properties during crystal growth in nickel was investigated by ensemble Kalman filter (EnKF)-based data assimilation, in which the phase-field simulation was combined with atomic configurations of molecular dynamics (MD) simulation. Negative temperature dependence was found in the solid-liquid interfacial energy, the kinetic coefficient, and their anisotropy parameters from simultaneous estimation of four parameters. On the other hand, it is difficult to obtain a concrete value for the anisotropy parameter of solid-liquid interfacial energy since this factor is less influential for the MD simulation of crystal growth at high undercooling temperatures.

Free energy barriers from biased molecular dynamics simulations.

Atomistic simulation methods for the quantification of free energies are in wide use. These methods operate by sampling the probability density of a system along a small set of suitable collective variables (CVs), which is, in turn, expressed in the form of a free energy surface (FES). This definition of the FES can capture the relative stability of metastable states but not that of the transition state because the barrier height is not invariant to the choice of CVs.

Bayesian inference of solid-liquid interfacial properties out of equilibrium.

Solid-liquid interfacial properties out of equilibrium provide the essential information required for understanding and controlling solidification microstructures in metallic materials. However, few studies have attempted to reveal all interfacial properties out of equilibrium in detail. The present study proposes an approach for simultaneously estimating all interfacial properties in a pure metal below the melting point on the basis of the Bayesian inference theory.

Molecular dynamics simulation of potentiometric sensor response: the effect of biomolecules, surface morphology and surface charge.

The silica-water interface is critical to many modern technologies in chemical engineering and biosensing. One technology used commonly in biosensors, the potentiometric sensor, operates by measuring the changes in electric potential due to changes in the interfacial electric field. Predictive modelling of this response caused by surface binding of biomolecules remains highly challenging.

Variational formulation of a quantitative phase-field model for nonisothermal solidification in a multicomponent alloy.

A variational formulation of a quantitative phase-field model is presented for nonisothermal solidification in a multicomponent alloy with two-sided asymmetric diffusion. The essential ingredient of this formulation is that the diffusion fluxes for conserved variables in both the liquid and solid are separately derived from functional derivatives of the total entropy and then these fluxes are related to each other on the basis of the local equilibrium conditions. In the present formulation, the cross-coupling terms between the phase-field and conserved variables naturally arise in the phase-field equation and diffusion equations, one of which corresponds to the antitrapping current, the phenomenological correction term in early nonvariational models.

Preferential synthesis of (6,4) single-walled carbon nanotubes by controlling oxidation degree of Co catalyst.

Chirality-selective synthesis of single-walled carbon nanotubes (SWNTs) has been a research goal for the last two decades and is still challenging due to the difficulty in controlling the atomic structure in the one-dimensional material. Here, we develop an optimized approach for controlling the chirality of species by tuning the oxidation degree of Co catalyst. Predominant synthesis of (6,4) SWNTs is realized for the first time.

Effects of CO adsorption on proton migration on a hydrated ZrO surface: an ab initio molecular dynamics study.

Hydration reactions on a carbonate-terminated cubic ZrO(110) surface were analyzed using ab initio molecular dynamics (AIMD) simulations. After hydration reactions, carbonates were still present on the surface at 500 K. However, these carbonates are very weak conjugate bases and only act as steric hindrance in proton hopping processes between acidic chemisorbed HO molecules (Zr-OH) and monodentate hydroxyl groups (Zr-OH).

Heterogeneity in homogeneous nucleation from billion-atom molecular dynamics simulation of solidification of pure metal.

Can completely homogeneous nucleation occur? Large scale molecular dynamics simulations performed on a graphics-processing-unit rich supercomputer can shed light on this long-standing issue. Here, a billion-atom molecular dynamics simulation of homogeneous nucleation from an undercooled iron melt reveals that some satellite-like small grains surrounding previously formed large grains exist in the middle of the nucleation process, which are not distributed uniformly. At the same time, grains with a twin boundary are formed by heterogeneous nucleation from the surface of the previously formed grains.

Dynamic behaviour of the silica-water-bio electrical double layer in the presence of a divalent electrolyte.

Electronic devices are becoming increasingly used in chemical- and bio-sensing applications and therefore understanding the silica-electrolyte interface at the atomic scale is becoming increasingly important. For example, field-effect biosensors (BioFETs) operate by measuring perturbations in the electric field produced by the electrical double layer due to biomolecules binding on the surface. In this paper, explicit-solvent atomistic calculations of this electric field are presented and the structure and dynamics of the interface are investigated in different ionic strengths using molecular dynamics simulations.