Alkyl Chain Length Dependence of Backbone-to-Backbone Distance in Polymerized Ionic Liquids: An Atomistic Simulation Perspective on Scattering

The backbone-to-backbone correlation length in polymerized ionic liquids (polyILs) manifested as the low-<i>q</i> peak in scattering profiles increases with increasing alkyl chain length, concomitant with ever-growing nonpolar domain size. Understanding the dependence of the correlation length on the pendant alkyl chain length is crucial to effectively designing polyILs for electrochemical applications. Herein, extensive atomistic MD simulations for a complete homologous series of poly­(<i>n</i>-alkyl­vinyl­imidazolium bis­(trifluoro­methyl­sulfonyl)­imide), poly­(C<i>n</i>Vim Tf2N) (<i>n</i> = 2–8), have been carried out to investigate the liquid structure with emphasis on scattering. Neutron scattering with isotopic labeling affords more versatile ways to vet the intrinsic structure, but different isotopically labeled neutron and X-ray scattering data do not necessarily lead to the same position of the low-<i>q</i> peaks. Such an unintended consequence has a nontrivial implication on exploitation of scattering experiments

EACS 2016 paper - Unscented Kalman filter for simultaneous identification of structural parameters and unknown excitations of a building structure

<div>EACS 2016 Paper No. 107<br></div><div><br></div>Identification of structural parameters under unknown excitations is an import task in structural health monitoring. This paper presents an efficient algorithm for simultaneously identifying structural parameters of a building structure and unknown excitations based on unscented Kalman filter (UKF). To utilize the UKF method directly, the observation equation of the structural system with unknown excitations is firstly transformed from a multiple linear regression equation to a simple linear regression equation by projecting on to the column space of influence matrix of unknown excitations. Then, an analytical recursive UKF algorithm is developed for identifying unknown excitations and structural parameters such as stiffness and damping. The feasibility and accuracy of the proposed algorithm are finally demonstrated in terms of an example shear building, in which the measurement noise is included. The results clearly exhibit that the proposed algorithm can simultaneously identify unknown excitations and structural parameters efficiently and accurately

Estimation of wheelset natural vibration characteristics based on transfer matrix method with various elastic beam models

The elastic vibration of the wheelset is a potential factor inducing wheel-rail defects. It is important to understand the natural vibration characteristics of the flexible wheelset for slowing down the defect growth. To estimate the elastic free vibration of the railway wheelset with the multidiameter axle, the transfer matrix method (TMM) is applied. The transfer matrices of four types of elastic beam models are derived including the Euler-Bernoulli beam, Timoshenko beam, elastic beam without mass and shearing stiffness, and massless elastic beam with shearing stiffness. For each type, the simplified model and detailed models of the flexible wheelset are developed. Both bending and torsional modes are compared with that of the finite element (FE) model. For the wheelset bending modes, if the wheel axle is modelled as the Euler-Bernoulli beam and Timoshenko beam, the natural frequencies can be reflected accurately, especially for the latter one. Due to the lower solving accuracy, the massless beam models are not applicable for the analysis of natural characteristics of the wheelset. The increase of the dividing segment number of the flexible axle is helpful to improve the modal solving accuracy, while the computation effort is almost kept in the same level. For the torsional vibration mode, it mainly depends on the axle torsional stiffness and wheel inertia rather than axle torsional inertia

Direct Comparison of Atomistic Molecular Dynamics Simulations and X‑ray Scattering of Polymerized Ionic Liquids

The design of solid-state electrolytes for electrochemical applications that utilize polymerized ionic liquids (polyILs) would greatly benefit from a molecular-level understanding of structure–function relationships. We herein use atomistic molecular dynamics simulations to investigate the structural properties of a homologous series of poly­(<i>n</i>-alkyl-vinylimidzolium bistrifluoromethylsulfonylimide) poly­(nVim Tf2N) and present the first direct comparison of the structure factors obtained from X-ray scattering and simulations. Excellent agreement is found in terms of peak position and shape. The backbone-to-backbone correlation length increases at a rate of 1 Å/CH₂. The longer alkyl chains lead to the longer backbone-to-backbone separation and the larger nonpolar nanodomains. This quantitative comparison of atomistic simulations to X-ray scattering will lead to a fundamental understanding in structure and morphology of polyILs and pave a path forward toward the rational design of future polyILs for electrochemical devices

Solubility of Gases in a Common Ionic Liquid from Molecular Dynamics Based Free Energy Calculations

Solubility of eight common gases in the 1-ethyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide, [emim]­[Tf₂N], ionic liquid was systematically investigated based on alchemical free energy calculations from molecular dynamics simulations. The simulated solubilities and trend in terms of Henry’s law constants agree qualitatively with the experiment. Polar gases such as H₂S and nonpolar gases with a large quadrupole moment such as CO₂ show the highest solubility, while nonpolar gases of small quadrupole moments (such as N₂ and H₂) are least soluble. The solute–ionic liquid interaction correlates with the observed solubility order. We also examined the temperature dependence of solubility for CO₂ and N₂ and found that the CO₂ solvation in IL is exothermic with a negative solvation enthalpy, while the N₂ solvation is endothermic, in agreement with the experiment

A Wind Load and Structural Parameters Estimation Approach for Building Structures

This paper was reviewed and accepted by the APCWE-IX Programme Committee for Presentation at the 9th Asia-Pacific Conference on Wind Engineering, University of Auckland, Auckland, New Zealand, held from 3-7 December 2017

A Divergence-free Multi-scale Synthetic Eddy Method for LES Simulation of ABL

This paper was reviewed and accepted by the APCWE-IX Programme Committee for Presentation at the 9th Asia-Pacific Conference on Wind Engineering, University of Auckland, Auckland, New Zealand, held from 3-7 December 2017

Windowed Carbon Nanotubes for Efficient CO₂ Removal from Natural Gas

We show from molecular dynamics simulations that windowed carbon nanotubes can efficiently separate CO₂ from the CO₂/CH₄ mixture, resembling polymeric hollow fibers for gas separation. Four CO₂/CH₄ mixtures with 10, 30, 50, and 80% CO₂ are investigated as a function of applied pressure from 80 to 180 bar. In all simulated conditions, only CO₂ permeation is observed; CH₄ is completely rejected by the nitrogen-functionalized windows or pores on the nanotube wall in the accessible time scale, while maintaining a fast diffusion rate along the tube. The estimated time-dependent CO₂ permeance ranges from 10⁷ to 10⁵ GPU (gas permeation unit), compared with ∼100 GPU for typical polymeric membranes. CO₂/CH₄ selectivity is estimated to be ∼10⁸ from the difference in free-energy barriers of permeation. This work suggests that a windowed carbon nanotube can be used as a highly efficient medium, configurable in hollow-fiber-like modules, for removing CO₂ from natural gas

Dipeptide-Based Chiral Tertiary Amine-Catalyzed Asymmetric Conjugate Addition Reactions of 5<i>H</i>‑Thiazol/Oxazol-4-Ones

Highly enantio- and chemo-selective 1,4-conjugate addition process of 5<i>H</i>-thiazol-4-ones with maleimides or 1,4-naphthoquinones, and 5<i>H</i>-oxazol-4-ones with maleimides were performed under a dipeptide-based tertiary amine (DP-UAA) catalyst. A series of valuable <i>N</i>,<i>S</i>- and <i>N</i>,<i>O</i>-containing heterocyclic compounds with excellent enantio- and disastereo-selectivities (up to >99% ee, > 20:1 dr) were attained

Table_1_Research on application of radiomics in glioma: a bibliometric and visual analysis.pdf

BackgroundWith the continuous development of medical imaging informatics technology, radiomics has become a new and evolving field in medical applications. Radiomics aims to be an aid to support clinical decision making by extracting quantitative features from medical images and has a very wide range of applications. The purpose of this study was to perform a bibliometric and visual analysis of scientific results and research trends in the research application of radiomics in glioma.MethodsWe searched the Web of Science Core Collection (WOScc) for publications related to glioma radiomics. A bibliometric and visual analysis of online publications in this field related to countries/regions, authors, journals, references and keywords was performed using CiteSpace and R software.ResultsA total of 587 relevant literature published from 2012 to September 2022 were retrieved in WOScc, and finally a total of 484 publications were obtained according to the filtering criteria, including 393 (81.20%) articles and 91 (18.80%) reviews. The number of relevant publications increases year by year. The highest number of publications was from the USA (171 articles, 35.33%) and China (170 articles, 35.12%). The research institution with the highest number of publications was Chinese Acad Sci (24), followed by Univ Penn (22) and Fudan Univ (21). WANG Y (27) had the most publications, followed by LI Y (22), and WANG J (20). Among the 555 co-cited authors, LOUIS DN (207) and KICKINGEREDER P (207) were the most cited authors. FRONTIERS IN ONCOLOGY (42) was the most published journal and NEURO-ONCOLOGY (412) was the most co-cited journal. The most frequent keywords in all publications included glioblastoma (187), survival (136), classification (131), magnetic resonance imaging (113), machine learning (100), tumor (82), and feature (79), central nervous system (66), IDH (57), and radiomics (55). Cluster analysis was performed on the basis of keyword co-occurrence, and a total of 16 clusters were formed, indicating that these directions are the current hotspots of radiomics research applications in glioma and may be the future directions of continuous development.ConclusionIn the past decade, radiomics has received much attention in the medical field and has been widely used in clinical research applications. Cooperation and communication between countries/regions need to be enhanced in future research to promote the development of radiomics in the field of medicine. In addition, the application of radiomics has improved the accuracy of pre-treatment diagnosis, efficacy prediction and prognosis assessment of glioma and helped to promote the development into precision medicine, the future still faces many challenges.</p