Evolution Of Profile Research Articles

Orbital Support and Evolution of Flat Profiles of Bars (Shoulders)

Many barred galaxies exhibit upturns (shoulders) in their bar-major-axis density profile. Simulation studies have suggested that shoulders are supported by looped x 1 orbits, occur in growing bars, and can appear after bar buckling. We investigate the orbital support and evolution of shoulders via frequency analyses of orbits in simulations. We confirm that looped orbits are shoulder-supporting, and can remain so, to a lesser extent, after being vertically thickened. We show that looped orbits appear at the resonance ( Ω φ − ΩP)/Ω R = 1/2 (analogous to the classical inner Lindblad resonance, and here called ILR) with vertical-to-radial frequency ratios 1 ≲ Ω z /Ω R ≲ 3/2 (vertically warm orbits). Cool orbits at the ILR (those with Ω z /Ω R > 3/2) are vertically thin and have no loops, contributing negligibly to shoulders. As bars slow and thicken, either secularly or by buckling, they populate warm orbits at the ILR. Further thickening carries these orbits toward crossing the vertical ILR [vILR, ( Ω φ − ΩP)/Ω z = 1/2], where they convert in-plane motion to vertical motion, become chaotic, kinematically hotter, and less shoulder-supporting. Hence, persistent shoulders require bars to trap new stars, consistent with the need for a growing bar. Since buckling speeds up trapping on warm orbits at the ILR, it can be followed by shoulder formation, as seen in simulations. This sequence supports the recent observational finding that shoulders likely precede the emergence of BP-bulges. The python module for the frequency analysis, naif, is made available.

Evolution of Infective Endocarditis Profiles in South-Central Chile: A Four-Decade Analysis of Surgical Patients

To describe the changes observed in operated patients with infective endocarditis (IE) in the south-central region of Chile during the last four decades. Case series study. The target population was patients diagnosed with IE and indication for valve surgery between 1983 and 2020 from a Chilean public hospital. The universe (n = 306) was divided into four groups according to the period of valve surgery. Sociodemographic and clinical variables between these groups were compared using the Kruskal-Wallis and Chi-square tests for independence. Cumulative survivals were calculated and compared using the Gehan-Breslow-Wilcoxon test. Age at diagnosis (p < 0.001), frequency of comorbidities (p < 0.001), clinical presentation compatible with acute kidney injury (p < 0.001), independent mitral valve involvement (p < 0.001), positivity of microbiological cultures (p < 0.012) and cumulative survival (p = 0,015) increased. The delay from symptom onset to diagnosis (p = 0.003), clinical presentation compatible with heart failure (p < 0.001), independent involvement of the aortic valve (p < 0.001), and surgical indication for large vegetation (p < 0.001) decreased. The IE profile of patients seen in a public hospital in the south-central region of Chile has undergone significant changes during the last four decades.

OBSERVATIONS AND MODELING OF EROSION AND RECOVERY OF A COUPLED BEACH-DUNE SYSTEM

The geomorphic and ecological vulnerability of barrier islands is influenced by the way they respond to oceanographic and anthropogenic forcing over a broad range of temporal scales. Integrated models capable of simulating these processes are increasingly necessary to understand barrier island trajectories under future conditions and to aid in management decisions by evaluating the impact of potential restoration activities. While there are numerical models capable of simulating some of the dominant barrier processes, the role of beach berm evolution is rarely included despite the important function of berms in sustaining beaches, enabling dune growth via Aeolian transport, and mitigating backshore and dune erosion during storm events. This is primarily due to a lack of available data that resolves details of beach profile evolution at necessary temporal scales (e.g., seasonal, post-storm recovery, etc.) to test and develop models and the inherent difficulty of including these intra-annual processes into decadal scale models of barrier island evolution. Here we describe a unique and growing dataset of environmental forcing and barrier island topographic change. We also use the dataset to develop and test a model for barrier island evolution and quantify the role of storms, moderate wave conditions, and wind-driven transport in dictating coastal change on various timescales.

CROSS-SHORE BEACH PROFILE SIMULATION IN THE SWASH ZONE OF NARRABEEN-COLLAROY BEACH

Sediment transport and, consequently, the beach profile changes in the swash zone are important to the overall sediment budget and beach profile evolution because the hydrodynamic condition in this zone is complex. One of the swash zone morphodynamic difficulties is estimating the beach profile accretion and erosion above the mean water level. Although there have been considerable studies and investigations into the swash zone morphodynamic, numerical models for predicting sediment transport rate and beach profile changes are limited. Therefore, this study examined a morphodynamic numerical model to predict beach profile evolution in the swash zone using a nearshore beach profile dataset measured at the Narrabeen-Collaroy beach, Australia.

Operando structural analysis of phase transition of graphite electrode during Li de-intercalation process using neutron and synchrotron radiation X-ray diffraction

Graphite is widely used as a negative electrode material for lithium-ion batteries. Although it is well known lithium ions are inserted between the graphene layers, the details of the structural transition they undergo are not well understood. In this study, we performed operando structural analyses of graphite electrode during the discharge process using neutron diffraction and synchrotron radiation X-ray diffraction and established a solid foundation to clarify the relationship among the LiCx composition, discharging profile, and phase evolution of lithium-intercalated graphite (LIG). The operando analyses enabled us to assess simultaneously the structural changes of LIG along the ab plane (in-plane structure) and the c-axis direction (stage structure). In the de-lithiation process, the intralayer transition was observed on the ab plane from the LiC6-type to the LiC9-type arrangement near the LiC18 composition. The LiC9-type arrangement was retained in the Li-poorer phases such as LiC27, LiC36, LiC54, and LiC72, where the Li de-lithiation proceeded with the interlayer transition to higher-order stages. The phase transition of LIG involves a rapid switchover between the LiC6-type and the LiC9-type intralayer arrangement along with the changes in the interlayer stage structure. A reaction mechanism for the configurational transition on the intralayer and interlayer structure was updated.

Core transport modelling of the DTT full power scenario using different fuelling strategies

A theory-based integrated modelling work of plasma response to deuterium fuelling in the new Divertor Tokamak Test facility (DTT) is performed, using the 1.5D transport code JETTO with the quasi-linear anomalous transport model QuaLiKiz for the core region. The full power DTT scenario E1 is investigated. It is characterised by 28.8 MW of Electron Cyclotron Resonance Heating, 10 MW of Neutral Beam Injection and 6 MW of Ion Cyclotron Resonance Heating to the plasma. Plasma density and temperature profile evolution is calculated up to the separatrix using two different fuelling methods, gas puffing and pellet injection, and two different seeding gases, argon and neon. To sustain the desired pedestal density level with gas puffing a big amount of neutral flux at the separatrix is needed. The feasibility limits of the pumping system are exceeded, regardless of the type of impurity introduced, thus making the use of pellets mandatory. The simulations performed with pellet injection as fuelling method predict that the pedestal density is well sustained with realistic parameters foreseen for the DTT pellet injector. Strong dependence of the core density on the electron cyclotron resonance (ECR) power deposition profile is found. Trapped Electron Modes dominance, low outward flux and strongly hollow density in the inner core region are foreseen with central peaked ECR power deposition profile. Ion Temperature Gradient modes dominance, inward flux and robust density sustainment on the whole radial interval are predicted for spread ECR power deposition, though with central density close to the ECR cut-off limit and with peaked impurity densities. An intermediate deposition extension is found to sustain the whole density profile and to obtain flatter core densities, as previously predicted for the reference full power DTT scenario by fixed pedestal simulations. The ECR deposition is negligibly modified by refraction changes both during a single pellet cycle and after several pellet cycles, indicating full compatibility between the ECR system and the pellet injection system.

EFFECTS OF EDGE ROUGHNESS ON SURFACE CHARGING IN PLASMA ETCHING

In the plasma etching technique, acquiring a high-quality transfer from the mask pattern onto the substrate under the suppression of the charging effects is of great significance. Most previous publications only focus on studying the charging phenomena on smooth round mask holes. This work shifted the target to an isolated mask hole with a rough edge using a classical particle simulation program, to examine the effects of edge roughness on surface charging for a mask hole. This study adopted the CF4 plasmas, due to the widely used fluorocarbon plasmas for the contact-holes. Simulated results indicate that the mask holes with various shapes present differences in electric field ([Formula: see text]-field) strength distribution, etching rate and profile evolution, relying on some condition parameters (roughness and reflection probability on the mask surface). The larger the dominant wavelength (DW), the more uniform the [Formula: see text]-field distribution around the edge of the mask hole will be. The simulation of the profile evolution further confirmed that the deformation is in keeping with the distribution of the [Formula: see text]-field. It was further found that the root mean square (RMS) of roughness increases with time in cases of the relatively small values of wavelength (10 and 35 nm) and decreases for other cases. Possible mechanisms behind have been discussed in detail. The findings of this work would shed light on an approach to maintain the pattern integrity.

Numerical investigation of residual stresses in thin-walled additively manufactured structures from selective laser melting

Selective laser melting (SLM), a metal laser powder bed fusion additive manufacturing method, involves several cycles of very high temperature gradient heating and cooling during the solidification of each layer, which can cause the accumulation of detrimental residual stresses in the 3D printed structure. This work uses a thermo-mechanical computational modeling approach to investigate the formation of residual stresses in thin-walled structures and also investigates the effects of varying taper on the evolution of residual stress profiles of the build. Three material grades; namely, Titanium alloy (Ti64), Stainless steel (SS316L) and Inconel (IN718) have been used for this study. The results show that varying taper thickness up to a certain value has a considerable effect on residual stress evolutions in thin-wall structures, however, beyond a certain value of the taper level, the residual stresses are observed to converge. Also, it is observed that the tensile stresses at the edges of the wall are almost equal or exceed the yield stress of the materials. Among the three material grades considered, the magnitude of residual stress was higher in Ti64 and the stresses are dominant in the build direction. The simulation framework is also applied to analyze the effect of residual stresses on the mechanical properties of complex thin-wall structures such as TPMS (Triply Periodic Minimum Surfaces) lattice structure, using Schwarz Primitive (SP) as a case study. It is observed that the residual stresses lower the effective elastic properties of the lattice structures by 6% ∼ 10% for the three material grades but has no effect on the effective plastic behavior of the material.

Controlling Bowing and Narrowing in SiO2 Contact-Hole Etch Profiles Using Heptafluoropropyl Methyl Ether as an Etchant with Low Global Warming Potential

Heptafluoropropyl methyl ether (HFE-347mcc3), as a lower-GWP (global warming potential) alternative to PFCs (perfluorocarbons), was used to etch SiO2 contact holes. The etch profiles of the SiO2 contact holes in HFE-347mcc3/O2/Ar plasmas showed more bowing at lower flow rate ratios of HFE-347mcc3 to Ar, whereas more narrowing occurred at higher ratios. The measurements of the angular dependences of the deposition rates of fluorocarbon films on the surface of SiO2 and the etch rates of SiO2 showed that the shape evolution of contact-hole etch profiles at different HFE-347mcc3/Ar ratios was attributed to an increase in etch resistance and a decrease in etch ability of the sidewalls of the contact hole with the increasing HFE-347mcc3/Ar ratio. This resulted in determining the optimum ratio of HFE-347mcc3 to Ar to achieve the maximum anisotropy of the contact hole etched in HFE-347mcc3/O2/Ar plasmas. By carefully selecting the specific flow rates of HFE-347mcc3/O2/Ar (9/2/19 sccm), a highly anisotropic and bowing-free SiO2 contact hole, with a 100 nm diameter and an aspect ratio of 24, was successfully achieved.

A Study on the Characteristics of Beach Profile Evolution According to the Particle Size Variation of Beach Nourishment

This study investigated the beach nourishment effect and topographical changes when using nourishment sand with relatively large particle diameters to perform beach nourishment on a beach subject to erosion. A physical model test was conducted in a 2D wave flume with an installed wind tunnel. The experiment examined the sediment transport mechanism under conditions with wind and waves. Although applying nourishment sand with large particle diameters attenuated sediment transport, the increase in particle diameter was not always proportional to the reduction in topographical changes. Increasing the particle diameter of the nourishment sand increased the friction force between particles, resulting in large-scale erosion and accretion around the coastline, and this trend increased with winds. Also, with wind, the wave run-up height increased, the undertow became stronger, and large-scale scouring occurred at the boundary between the nourishment sand and the existing beach. Increasing the particle diameter of the nourishment sand played a role in reducing the run-up phenomenon (d50: 1.0 mm with 24–50%, d50: 5.0 mm with 59–83%), and the range of particles moved by winds also decreased (d50: 1.0 mm with 10–38%, d50: 5.0 mm with 5–37%).

Systemic Lupus Erythematosus: Female Versus Male

Introduction: Systemic lupus erythematosus (SLE) is an autoimmune disease, uncommon in men. The study of gender differences in SLE has been the subject of several publications. The main aim of our study is to identify gender differences in terms of clinical manifestations, immunological profile, activity score, and disease evolution in our Moroccan population. Results: We analyzed 279 patients (21 men versus 258 women), with a mean age at diagnosis of 37.54 +/- 23.39 years for women and 42.74 +/- 16.33 years for men. A comparison of clinical and immunological manifestations showed that male patients had a higher prevalence of renal involvement, lymphopenia, leukopenia, and general signs, but the difference was not significant. However, we did establish a significant correlation between male sex and cardiac involvement (P=0.013) as well as neuropsychiatric involvement (P=0.05). We also observed a significant association with anti-SSA antibodies (p=0.007). Dermatological and articular events were more frequent in women than in men, with a statistically significant association between female gender and photosensitivity (p=0.037). There was also a statistically significant correlation between women with RNP antibodies (p = 0.016) and anti-native DNA antibodies (p=0.047). The outcome was good in 67% of men (vs. 86.2% p=0.802), with response to treatment and control of the disease, and poor in 33% of men (vs. 13.9% %, p=0.019). Conclusions: Our study reveals the influence of gender on certain clinical manifestations of SLE. Dermatological and articular manifestations are more frequent in women, whereas men present a more severe disease, with a higher frequency of renal, cardiac, and neurological involvement.

A Network Traffic Abnormal Detection Method: Sketch-Based Profile Evolution

Network anomaly detection faces unique challenges from dynamic traffic, including large data volume, few attributes, and human factors that influence it, making it difficult to identify typical behavioral characteristics. To address this, we propose using Sketch-based Profile Evolution (SPE) to detect network traffic anomalies. Firstly, the Traffic Graph (TG) of the network terminal is generated using Sketch to identify abnormal data flow positions. Next, the Convolutional Neural Network and Long Short-Term Memory Network (CNN-LSTM) are used to develop traffic behavior profiles, which are then continuously updated using Evolution to detect behavior pattern changes in real-time data streams. SPE allows for direct processing of raw traffic datasets and continuous detection of constantly updated data streams. In experiments using real network traffic datasets, the SPE algorithm was found to be far more efficient and accurate than PCA and Basic Evolution for outlier detection. It is important to note that the value of φ can affect the results of anomaly detection.

Geochemical behaviors of uranium and thorium during weathering and pedogenesis of carbonate rock: constraint from their speciation.

During weathering and pedogenesis of carbonate rock with poor-uranium (U) and thorium (Th), U and Th present the characteristics of strong leaching (especially U) and significant residual enrichment, the cause of which is still unclear. In this paper, a weathering profile developed by dolomite in karst area of Guizhou province in southwest China was selected, which showed zonation characteristics of bedrock (Y), powdery rock (Yf), and soil layer (T1 to T12) from the bottom to up. Through the determination of the occurrence speciation of U and Th in Y and weathering profile, combined with mineralogical, geochemical characteristics, and element mass balance calculation, the constraints of U and Th speciation on the geochemical behavior of U and Th during the weathering of carbonate rock were revealed. The results proved that U and Th in Y preferentially existed in acid insoluble phase, for example, the contents of U and Th in Y were 0.90 mg·kg-1 and 0.28 mg·kg-1, respectively, while those in acid insoluble matter were 2.34 mg·kg-1 and 2.57 mg·kg-1, respectively, but because the mass percentage of acid insoluble matter was extremely low (0.95%), the mass percentages of U and Th in the acid soluble phase in the whole rock were absolutely superior (96% of U and 86% Th). The U and Th in the acid soluble phase of Y were mainly adsorbed on the crystal surface of carbonate minerals or existed in the cement, and the U and Th in the carbonate lattice only accounted for a small proportion. From Y to Yf with the initial dissolution, U and Th released from the surface of carbonate minerals and cements were in carbonate-rich alkaline environment, and these portions of U and Th were leached out, resulting in strong loss of U and Th in the Yf (the loss rates are 83% of U and 65% of Th, respectively). From the Yf to the overlying soil layer T1, the carbonate components were completely dissolved, and the U and Th released from the carbonate lattice showed different behaviors, where U was completely leached and Th tended to stay in the weathered residue. Thus, in the soil layer T1 formed by Y or Yf , the residual U was the inheritance of the U in the acid insoluble phase of Y; For Th, it not only inherited the Th of acid insoluble phase of Y, but also superimposed the Th from carbonate lattice in Y. On the other hand, during the evolution process from Y to Yf and to soil layer T1, with the dissolution of carbonate, the acid insoluble phase also showed a significant tendency of chemical weathering. However, the U and Th in the Y acid insoluble phase were not leached with the decomposition of the acid insoluble phase but were redistributed among the residual phases. For the geochemical behaviors of U and Th in the evolution of soil profile (T1~T12), they were subjected to the occurrence speciation of U and Th in T1 and the change of U and Th occurrence speciation with the upward direction of soil profile. The U and Th released from the carrier minerals were mainly redistributed among the residual solid phases, which weakened the intensity of their further loss. This study deepens the understanding of the geochemical behavior of radionuclides in karst environment and provides reference for the treatment of radioactive pollution in karst areas.

Temporal Success Analyses in Music Collaboration Networks: Brazilian and Global Scenarios

Collaboration is a part of the music industry and has increased over recent decades; but little do we know about its effects on success and evolution. Our goal is to analyze how success has evolved over collaboration networks and compare its global scenario to a local, thriving one: the Brazilian music industry. Specifically, we build collaboration networks from data collected from Spotify's Global and Brazilian daily charts, analyze them and identify collaboration profiles in such networks. Analyses over their topological characteristics reveal collaboration patterns mapped into four different profiles: Standard, Niche, Ephemeral and Absent, where the two first have a higher level of success. Furthermore, we do deeper by evaluating the temporal evolution of such profiles through case studies: pop and k-pop globally, and pop and forró in Brazil. Overall, our findings emphasize the importance of collaboration profiles in assessing success, and show differences between the global and Brazilian scenarios.

Experimental and numerical analysis of the thermal behaviour of a single-phase immersion-cooled data centre

Server power densities are foreseen to increase, and conventional air-cooling systems will struggle to cope with thermal demand. Single-phase immersion systems are a promising alternative to operate very intensive workload such as high-performance computing, cryptocurrencies mining or research activities. However, few companies deal with this kind of system and there is a lack of energy models that can reproduce an accurate analysis of the system behaviour. This study addresses the experimentation, data collection, and model validation of a single-phase immersion cooling system where 54 open compute project servers, each with a peak power of 400 Watts that are submerged and operated in a dielectric coolant. Results show the evolution of the thermal profile of the system under static and dynamic workloads, and it provides a correlation of server energy use under various system temperatures. The energy model is presented, validated against real data, and exploited to investigate the system response to different cooling conditions. In conclusion, the study demonstrates the validation of the energy model and supports the basis for further investigation.

A Thin Elastic Plate Model for Thermally Contracting Young Oceanic Lithosphere: Insights From Comparison With Modern Seafloor Observations

AbstractWe find at fast‐ and intermediate‐spreading seafloor that their ridge‐parallel bathymetric profiles between two neighboring fracture zones, excluding the part of the seafloor inward to fracture zone (FZ) valley, are predominantly upward concave. The temporal evolution of the bathymetric profiles from the lithosphere formed at the Chile Rise is characterized by (a) the rapid growth of the middle deflection to about 200 m relative to the ends for the first few millions of years and (b) a steady state afterward. We show that these characteristics and the upward‐concave sense of bending can be reasonably explained as the flexure of a thin elastic plate contracting thermally from the top while cooling. The best‐fitting model needs only about 10% of the thermal bending moment based on the half‐space cooling model and the free‐end assumption. Our model is consistent with the recent observations that oceanic lithosphere is cut open at a FZ valley, which disprove the previous assumption that ocean floor is bent down forming the valley walls.

Profiles of Chinese teachers' emotional labor: Evolution and relations with job demands, resources, and burnout

Based on the person-centered approach, we investigated the evolution of teachers' emotional labor profiles and examined how occupational stress and organizational support predicted changes in profile membership, and the difference in burnout among different profiles. Data were collected from 829 Chinese primary and secondary teachers in a two-wave longitudinal test over six months. Latent profile analysis identified four emotional labor profiles, while latent transition analysis found that the profiles exhibited a latent transition probability. Occupational stress and organizational support can predict the negative and positive latent transition of profiles, and four profiles were related to different levels of teacher burnout.

Improving performance prediction of diode end-pumped solid-state Nd:YAG rod amplifiers by incorporating pump mode evolution.

Master Oscillator Power Amplifier (MOPA) systems find extensive use in laser development to increase the optical power of laser emissions from a Master Oscillator (MO). Commonly used are the cylindrical rod MOPAs that are optically excited using a multimode fiber-coupled (FC) diode laser emission in an end-pumped configuration. Current analytical 3D models that incorporate thermal effects, gain saturation, and iterative Fourier beam propagation methods, collectively, rely on static approximations of the evolution of the FC pump beam profile over the longitudinal volume of the amplifier crystal. Furthermore, in general, the spectral behavior of the FC diode emission is assumed to be static, and the thermal wavelength shift is not accounted for in the simulation. In this work, we demonstrate a novel approach for accurate modeling of the multimode FC pump beam emission as a complex field using a phase-only Gaussian to flat-top (FT) diffractive optical element, thus allowing for the inclusion of the pump beam into the iterative propagation method. Additionally, we present a method for precise calibration of the model using simple experimental measurements of the diode emission spectrum. The theoretical model is experimentally validated using an end-pumped Nd:YAG crystal rod to perform single-pass amplification of a Gaussian beam, showing excellent agreement with predicted output powers over the calibrated range of pump powers. Furthermore, we provide experimental data that exhibits a strong correlation between the Gaussian to FT phase-only transformation and the multimode FC diode evolution in free-space propagation.

Morphological description of sagittal lumbar spinal alignment using curve magnitude, span, and apex—the multiethnic alignment normative study (MEANS)

Current definition of lumbar lordosis uses the L1-S1 angle. Prevailing classification of sagittal spinal morphology, derived from a young adult population, classifies the spine into four subtypes defined by their sacral slope (SS) and curve morphology. To describe physiological sagittal alignment of the lumbar spine across age groups using three main parameters that dictate the lumbar curve: angular magnitude, span, and apex. A large, multicenter, cross-sectional radiographic comparison study. Four hundred sixty-eight healthy, asymptomatic subjects aged 18 to 80 years from five countries (184 males, 284 females; 98 France, 119 Japan, 79 Singapore, 80 Tunisia, 92 USA, mean age 40.61±14.99 years). Sagittal lumbar profile subtypes clustered based on lumbar curve angular magnitude (ie, Cobb angle of the lumbar lordosis), span, and apex, and described by sagittal radiographic parameters. Subjects underwent whole-body low-dose EOS stereoradiographs. Comparisons between conventional L1-S1 lumbar lordosis (cLL) and true lumbar lordosis (tLL, defined by the inflection-S1 angle) were conducted. Using the K-means clustering algorithm, lumbar curve angular magnitude, span and apex were used to classify sagittal spinal morphology into subtypes, stratified across age groups. Further univariate and multivariate analyses were conducted to compare radiographic parameters across subtypes, and identify predictors for the lumbar curve's angular magnitude, span and apex. Mean cLL was -57.27±11.37°, and tLL was -62.62±10.76°. Using tLL, instead of cLL, to describe sagittal spinal morphology, we found significant differences in terms of angular magnitude of the lumbar curve, the median thoracolumbar inflection vertebral level and pelvic incidence-lumbar lordosis mismatch Multivariate analysis found a larger SS, more positive T9 tilt, and more kyphotic T4-T12 predictive for a more lordotic tLL, while a larger overhang distance predicted for a less lordotic tLL (p-values<.001). In addition, a larger T9 tilt, less lordotic L1-L5 and smaller PT were predictors of a more caudal thoracolumbar inflection and lumbar apical vertebral levels (p-values<.001). Sagittal lumbar profiles of subjects age<30 years, 30≤age<60 years and age≥60 years, could be classified into 4, 6, and 3 subtypes, respectively. Sagittal lumbar profile subtypes vary across age groups, with more homogenous morphologies at the extremes of ages. Improved understanding of the morphological evolution of sagittal spinal profiles with age in asymptomatic individuals will help guide future individualized surgical treatment.

Interfacial structure of protic and aprotic ionic liquid-DMSO-Li salt mixtures near charged and neutral electrodes: A Molecular Dynamics study

In this paper we report classical Molecular Dynamics simulations of the interfacial structure of two ternary mixtures, based on both a protic (ethylammonium nitrate, EAN) and an aprotic (1-ethyl-3-methylimidazolium tetrafluoroborate, EMIMBF4) ionic liquid. A molecular solvent (dimethylsulfoxide, DMSO) and a lithium salt with common anion are the rest of the components of the mixtures. The simulations were performed with implicit graphene walls, both neutral and charged with a surface charge density of ±1 e/nm2. Density, charge and electrostatic potential profiles as well as integral capacitances were calculated for all systems. For both liquids, the evolution of the density profiles throughout the DMSO concentration range are in accordance with previously characterized bulk properties of such systems. In the case of charged interfaces, the adsorption of Li+ cations into the negative electrode was found to be possible for the protic liquid, but unfavourable in the case of the aprotic one. Moreover, the probability distribution functions for the orientation of all molecular species near the interfaces were computed, and they indicate a tendency of the solvent molecules to form a dense layer at the interface separating the ionic liquids from the electrodes. The influence of hydrogen bonds in determining the dissimilitudes between protic and aprotic mixtures is highlighted.