Structure Model Research Articles

Unified Aedes aegypti Protein Resource Database (UAAPRD): An Integrated High-Throughput In Silico Platform for Comprehensive Protein Structure Modeling and Functional Target Analysis to Enhance Vector Control Strategies.

A comprehensive examination of Aedes aegypti's proteome to detect key proteins that can be targeted with small molecules can disrupt blood feeding and disease transmission. However, research currently only focuses on finding repellent-like compounds, limiting studies on identifying unexplored proteins in its proteome. High-throughput analysis generates vast amounts of data, raising concerns about accessibility and usability. Establishing a dedicated database is a solution, centralizing information on identified proteins, functions, and modeled structures for easy access and research. This study focuses on scrutinizing key proteins in A. aegypti, modeling their structures using RaptorX standalone tool, identification of druggable binding sites using BiteNet, validating the models via Ramachandran plot studies and refining them via 50-ns molecular dynamic simulations using Schrodinger Maestro. By analyzing ~ 18k proteins in the proteome of A. aegypti in our previous studies, all proteins involved in the light and dark circadian rhythm of the mosquito, inclusive of proteins in blood feeding, metabolism, etc. were chosen for the current study. The outcome is UAAPRD, a unique repository housing information on hundreds of previously unmodeled and un-simulated mosquito proteins. This robust MYSQL database ( https://uaaprd.onrender.com/user ) houses data on 309 modeled & simulated proteins of A. aegypti. It allows users to obtain protein data, view evolutionary analysis data of the protein categories, visualize proteins of interest, and send request to screen against the pharmacophore models present in UAAPRD against ligand of interest. This study offers crucial insights for developing targeted studies, which will ultimately contribute to more effective vector control strategies.

Local parallel free generation and dynamic affine transformation method for soil three-dimensional pore structure information model

The soil three-dimensional (3D) pore structure information model has become a new hotspot in the research of cross-scale disposal of information such as ecology, engineering, and geology. It can solve problems such as the intelligent evaluation of ecological water–soil–air–plant feedback, intelligent risk control of foundation compression deformation, and multiscale intelligent disaster prediction and prevention. However, the current soil 3D pore structure model primarily draws on the global one-time static generation in simulation software, leading to low reliability, low stability of multiple generations, poor variability, difficulty in real-time transformation, high consumption of computing resources, and long generation time, making it challenging to meet the requirements of the rapid processing of information models. Therefore, this study adopts the 3D Drawing Protocol (WebGL) technology and implements the scaling, rotation, and translation transformation of 3D pore structures based on the principle of dynamic affine transformation. The random generation and distribution of pores are realized using the improved Monte Carlo method, and the loading response efficiency of the system is optimized. The dynamic interactive operation of arbitrary increasing and decreasing of pore model is realized using the ray and plane intersection detection principle. Finally, this information system established a visual correlation between the content and reaction time of water-retaining agents and soil porosity and pore distribution through tests on the impact of water-retaining agents on soil pore changes. The information system achieved the real-time tracking of soil pore changes under the action of water-retaining agents. This research solves the problems of static and low generation efficiency of the soil mesopore structure in traditional models and realizes the real-time characterization and visualization of dynamic changes and the distribution of the soil pore structure under the influence of external conditions, which can provide an intuitive visualization platform for mesogeological structure research.

Petro-elastic model of the multiple pore-crack structure of carbonate rocks based on digital cores

Petro-elastic model of the multiple pore-crack structure of carbonate rocks based on digital cores

On the structure of Tl2Pb(SO4)2 and crystal chemistry of thallium‐containing sulfates

Single crystal of a thallium‐containing sulfate Tl2Pb(SO4)2 was prepared through hydrothermal crystallization starting from Tl2CO3, Pb(NO3)2 and H2SO4. The crystal structure was solved from single‐crystal X‐ray diffraction data: Tl2Pb(SO4)2 crystallizes in space group R[[EQUATION]]m with lattice parameters of a = 5.5955(2) Å, c = 22.1001(9) Å, and Z = 3, which is also corroborated by Rietveld refinement on X‐ray powder data. The crystal structure can be regarded as [Pb(SO4)2]2‐ sheets intercalated by double layers of Tl+ along the c‐axis. From a mineralogical perspective, Tl2Pb(SO4)2 belongs to the palmierite family and can further be classified within palmierite‐supergroup. Validation of the structure models was carried out utilizing various concepts including Bond Valence (BV), Charge Distribution (CD) and Madelung Part of Lattice Energy (MAPLE). Notably, a contrast in stereochemical activity of 6s2 lone electron pair (LEP) between Tl+ and Pb2+ is interpreted in terms of bonding behaviours as well as Wang‐Liebau Eccentricity (WLE) parameters. Moreover, an extensive investigation into the crystal chemistry of thallium‐containing sulfates was conducted for the first time, focusing on the coordination environment and bonding behaviour of Tl+ and corresponding WLE parameters. A comparative analysis of these structurally related compounds including Tl2Pb(SO4)2, Tl3H(SO4)2, TlBi(SO4)2, TlIn(SO4)2, TlRh(SO4)2, and TlAl(SO4)2 was delineated.

Modelling of negative equivalent magnetic reluctance structure and its application in weak-coupling wireless power transmission

In weak-coupling wireless power transmission, increasing operating frequency, and incorporating metamaterials, resonance structures or ferrite cores have been explored as effective solutions to enhance power efficiency. However, these solutions present significant challenges that need to be addressed. The increased operating frequency boosts ferrite core losses when it exceeds the working frequency range of the material. Existing metamaterial-based solutions present challenges in terms of requiring additional space for slab installation, resulting in increased overall size. In addition, limitations are faced in using Snell’s law for explaining the effects of metamaterial-based solutions outside the transmission path, where the magnetic field can not be reflected or refracted. To address these issues, in this work, the concept of a negative equivalent magnetic reluctance structure is proposed and the metamaterial theory is extended with the proposed magnetic reluctance modelling method. Especially, the negative equivalent magnetic reluctance structure is effectively employed in the weak-coupling wireless power transfer system. The proposed negative equivalent magnetic reluctance structure is verified by the stacked negative equivalent magnetic reluctance structure-based transformer experiments and two-coil mutual inductance experiments. Besides, the transmission gain, power experiments and loss analysis experiments verify the effectiveness of the proposed structure in the weak-coupling wireless power transfer system.

Measuring childbirth-related posttraumatic stress disorder: Psychometric properties of the Italian version of the City Birth Trauma Scale (City BiTS).

The City Birth Trauma Scale (City BiTS) assesses postpartum posttraumatic stress disorder (PTSD) based on the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) criteria. Although it has been validated worldwide, predictive validity has not been previously examined. Moreover, no Italian version of the scale exists. This study aimed to test the bifactor latent structure and alternative models, internal consistency, test-retest reliability, convergent validity, divergent validity, and predictive validity of the City BiTS. Women (N = 629) who had given birth within the past 3 months completed an online survey including sociodemographic and obstetric characteristics, the City BiTS, the Impact of Event Scale-Revised, and the Edinburgh Postnatal Depression Scale. After 3 months, women completed the City BiTS again and reported their intention to breastfeed during the 1-year postpartum. Exploratory factor analysis confirmed the two-factorial structure. In confirmatory factor analysis, the two-factorial solution showed the best model fit. Internal consistency was good to excellent for the subscales and the total scale. Correlation analyses showed strong convergent validity with the Impact of Event Scale-Revised, high divergent validity with the Edinburgh Postnatal Depression Scale, high test-retest reliability, and good predictive validity with the intention to exclusively breastfeed. Moreover, the Birth-Related Symptoms subscale distinguished between different types of delivery. The City BiTS-Italian is the first measure evaluating and diagnosing childbirth-related PTSD symptoms based on Diagnostic and Statistical Manual of Mental Disorders (5th ed.) in Italy. The factorial structure and validity reported in other cultural contexts were confirmed; moreover, findings add evidence to the scale's temporal stability and predictive validity. Besides contributing to clinical purposes, the City BiTS-Italian will facilitate international comparability regarding the prevalence of PTSD following childbirth. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Three-Dimensional Structure of Human Epididymis Protein 4 (HE4): A Protein Modelling of an Ovarian Cancer Biomarker Through In Silico Approach

The Human Epididymis Protein 4 (HE4) biomarker has been extensively investigated for its potential in diagnosing ovarian cancer (OC). For the application of diagnostic techniques and drug delivery, it is crucial to understand the protein tertiary structure. However, the Protein Data Bank (PDB) does not currently contain the three-dimensional (3D) structure of HE4. Therefore, an in silico analysis was conducted to model the HE4 protein using AlphaFold, I-TASSER, and Robetta servers, with the sequence retrieved from UniProt (ID: Q14508). These three servers employed deep learning algorithms, threading templates, and de novo methods, respectively. Subsequently, Molecular Dynamics (MD) simulation using the GROMACS software package improved each 3D structure model, resulting in optimized and refined structures: RF1, RF2, and RF3. PROCHECK and ERRAT programs were employed to assess the structure quality. The Ramachandran plots from PROCHECK indicated that 100% of residues were within the allowed regions for all servers except for I-TASSER. For the refined structures, RF1 and RF3, all residues were concentrated within the allowed regions. According to the ERRAT program, the RF1 model exhibited the highest overall quality factor of 97.701, followed by RF3 and AlphaFold models with scores of 94.643 and 93.750, respectively. After these validations, RF1 emerged as the most accurately predicted 3D structure of HE4 and has one tunnel identified by CAVER 3.0 tool that facilitates the transportation of small particles to the active site, supported by FTsite and PrankWeb binding site predictions. This model holds potential for various computational studies, including the development of OC diagnostic kits. It will enhance our comprehension of the interactions between the protein and other biomolecules.

DFT2FEFFIT: a density-functional-theory-based structural toolkit to analyze EXAFS spectra

This article presents a Python-based program, DFT2FEFFIT, to regress theoretical extended X-ray absorption fine structure (EXAFS) spectra calculated from density functional theory structure models against experimental EXAFS spectra. To showcase its application, Ce-doped fluorapatite [Ca10(PO4)6F2] is revisited as a representative of a material difficult to analyze by conventional multi-shell least-squares fitting of EXAFS spectra. The software is open source and publicly available.

Spike and hike modeling for interest rate derivatives: with an application to SOFR caplets

After the replacement of Libor with alternative reference rates across the world, market participants must now adjust to a variety of changes to both contract terms and market rate dynamics. Focusing mostly on the new SOFR rate in the US, this paper considers the interaction of two important characteristics of SOFR derivatives: the backward-looking settlement style of SOFR floating rate payments; and the historically ‘jagged’ nature of SOFR time series. We introduce mechanisms that allow us to modify existing term structure models to incorporate rich dynamics for both ‘surprising’ and anticipated spikes and hikes in overnight rates. Numerical tests on SOFR-style caplets show that such model enhancements can produce significant effects on implied caplet volatility levels and skews. Besides establishing a practitioner-friendly framework for derivatives pricing, our paper is broadly applicable to scenario generation and risk management in any market with discontinuous rates dynamics.

Research on Collapse Testing of Nuclear Icebreaker Reactor Hull Structure Based on Distortion Similarity Theory

In this study, the finite element method combined with the model test method are used to investigate the ultimate strength of a target ship reactor hull structure under a pure bending load. Based on the distortion similarity theory and nonlinear similarity method, a scale model of the actual ship reactor hull structure is designed and the model collapse test is conducted. The ultimate bending moment obtained by the model test is transformed to the actual ship through the similarity transformation relationship and compared with the nonlinear finite element analysis result of the actual structure. The results are consistent with each other, which indicates that the collapse characteristics of the actual ship reactor hull structure can be better forecasted using the model test results when the test model is designed based on the nonlinear similarity method and distortion similarity theory.

Study on updating finite element model of steel truss structure based on knowledge-enhanced deep reinforcement learning

Accurate assessment of the damage to a structure is the key to structural health monitoring. Among them, one effective means to assess the real-time status of the structure is by establishing a finite element model (FEM) of the structure and updating it synchronously. Previous research mainly updates the FEM of the structure with a certain moment in time without considering the continuous changes of structural parameters over a longer time. In this paper, we propose a FEM updating method for steel truss structure based on knowledge-enhanced deep reinforcement learning, which introduces long short-term memory (LSTM) network based on a deep deterministic policy gradient (DDPG) algorithm and constructs a knowledge-enhanced noise function (NF) module based on parametric analysis. The NF-LSTM-DDPG algorithm can fit a continuous variation of structural parameters. The ablation experiments revealed that the LSTM network and the NF module facilitate the exploration and learning ability of the DDPG algorithm. The NF-LSTM-DDPG algorithm is used in an actual steel truss structure case, and the variation rules of the elastic modulus and support deviations obtained from the solution are consistent with the actual situation. The average relative error of the 34 strain measurement points after updating is 14.147 %, and the relative error is higher than 20 % in only 13 days out of 187 days of continuous monitoring. Five days were selected for the comparative study, and the experimental results show that the relative error of the NF-LSTM-DDPG algorithm is 13.206 %, which is higher than that of the particle swarm optimization algorithm and the simulated annealing algorithm. The change of elastic modulus updated based on the NF-LSTM-DDPG algorithm is more reasonable than other algorithms.

Spectator Exciton Effects in Nanocrystals III: Unveiling the Stimulated Emission Cross Section in Quantum Confined CsPbBr3 Nanocrystals.

Quantifying stimulated emission in semiconductor nanocrystals (NCs) remains challenging due to masking of its effects on pump-probe spectra by excited state absorption and ground state bleaching signals. The absence of this defining photophysical parameter in turn impedes assignment of band edge electronic structure in many of these important fluorophores. Here we employ a generally applicable 3-pulse ultrafast spectroscopic method coined the "Spectator Exciton" (SX) approach to measure stimulated-emission efficiency in quantum confined inorganic perovskite CsPbBr3 NCs, the band edge electronic structure of which is the subject of lively ongoing debate. Our results show that in 5-6 nm CsPbBr3 NCs, a single exciton bleaches more than half of the intense band edge absorption band, while the cross section for stimulated emission from the same state is nearly 6 times weaker. Discussion of these findings in light of several recent electronic structure models for this material proves them unable to simultaneously explain both measures, proving the importance of this new input to resolving this debate. Along with femtosecond time-resolved photoluminescence measurements on the same sample, SX results also verify that biexciton interaction energy is intensely attractive with a magnitude of ∼80 meV. In light of this observation, our previous suggestion that biexciton interaction is repulsive is reassigned to hot phonon induced slowdown of carrier relaxation leading to direct Auger recombination from an excited state. The mechanism behind the extreme slowing of carrier cooling after several stages of exciton recombination remains to be determined.

한국판 지속적 비탄 척도 개정판(K-PG13-R)의 타당화 연구

Objectives The purpose of this study was to adapt and validate the revised version of the Prolonged Grief Scale (PG-13-R), developed in accordance with the diagnostic criteria for Prolonged Grief Disorder inserted in DSM-5-TR, into Korean. The study aimed to confirm the factor structure, validity, and reliability of the scale. Methods Through translation and back-translation processes, the Korean version of the Prolonged Grief Scale (K-PG13-R) was constructed. The study participants were adults aged 18 and above who had experienced bereavement, with a bereavement period ranging from 1 to 5 years. Exploratory factor analysis, reliability, and validity testing were conducted with a sample of 266 bereaved individuals, and confirmatory factor analysis was performed with a separate sample of 402 bereaved individuals. Results Through exploratory factor analysis, it was confirmed that the scale consists of a single factor. This is consistent with findings from the development of the PG-13-R scale using samples from the United States, the Netherlands, and the United Kingdom. As a result of conducting confirmatory factor analysis using a different sample, it was verified that the single-factor structure model extracted through exploratory factor analysis was appropriate. Additionally, the scale demonstrated high internal consistency, as well as high convergent and concurrent validity, confirming that its reliability and validity are at acceptable levels. Conclusions This study holds significance in adapting and validating the PG-13-R revised in accordance with the formal diagnostic criteria for Prolonged Grief Disorder in DSM-5-TR into Korean. It is anticipated that this scale will contribute to evaluating and providing timely treatment for bereaved individuals in need of therapy.

Study on the Stability and Reasonable Width of Coal Pillars in “Three Soft” Coal Seams Based on a Physical Similarity Simulation Experiment

As the depth of coal seams increases and the demand for coal grows, the deformation and failure of roadways and coal pillars also intensify. To address the instability of roadways, it is crucial to study the appropriate dimensions for coal pillars. This paper focuses on the 1513 working face of the No. 5 coal seam at Anyang Coal Mine to address the issue of insufficient basis for determining coal pillar width. Through field observations and physical similarity simulations, this study examines the overlying strata failure patterns above coal pillars post-mining and the bearing structure formed by key layers. The relationship between these factors is analyzed using theoretical analysis and physical similarity simulations. A mechanical model of the coal pillar and the “hinged-hinged” overlying strata failure structure is established, analyzing the fracture characteristics of the overlying strata and the bearing structure of the coal pillar to determine the optimal coal pillar width under these conditions. The results indicate that when the coal pillar width is optimized from 25 m to 14 m, the overlying bearing layer is disrupted by the mining activities at the working face, with the lower key layer forming a “hinged” structure upon fracture. As mining progresses, the height of the overlying strata fractures gradually increases, causing the upper key layer to also fracture and form a “hinged-hinged” structure between the high and low bearing layers. According to the “three zones” development law, the height of overlying strata failure does not continue to increase indefinitely, and the coal pillar is affected by the “hinged-hinged” structure of the bearing strata. A mechanical model of the coal pillar bearing structure is established based on the fracture combination structure of the bearing strata. By calculating the load on the “hinged-hinged” structure of the overlying strata, the appropriate coal pillar width is determined to be 15 m. Theoretical calculations, physical similarity simulation experiments, and field applications show that without changing the support conditions, the deformation of the roadway is greater when the coal pillar is narrowed, compared to its original width. The maximum deformation, located 60 m ahead of the working face, increased by 41–42%, while deformation in other areas was relatively minor. This validates the reasonableness of the determined coal pillar width.

Odd-even trends in the series of new bis(α,ω-alkanediamine)dibromocadmium(II) coordination polymers: Crystal structure and thermal decomposition

In this paper, organic-inorganic coordination polymers of the CdBr2(H2N-(CH2)n-NH2) general formula, where n = 4 – 10 and 12, were studied. All the materials were synthesized as very fine powders from metal salt and diamine solutions following an analogous simple procedure. Scanning electron microscopy (SEM) images and recorded powder X-ray diffraction patterns (PXRD) allowed for the assessment of the purity and crystallinity of the products. Based on the collected diffraction data, lattice parameters and symmetry were determined. For five of the synthesized compounds (n = 4, 6, 7, 8, and 12) that were of relatively high purity and sufficient crystallinity, crystal structure models were determined and refined. It was found that the structure symmetry depends on the parity of the number of carbon atoms in the diamine molecules. Structures of the investigated compounds belonging to the even series are centrosymmetric while the ones from the odd series are not (P21 space group). Structures’ symmetry of compounds based on even diamines decreases from P2/m to P1¯ with increasing length of the organic molecules. Diamine molecules are aligned parallel to the diagonals of the (010) faces of the unit cell and there is an almost perfectly linear correlation between the value of a lattice parameter and the number of C atoms. There are, however, separate trends for even or odd series. Differential scanning calorimetry (DSC) and non-ambient PXRD measurements provided information about the thermal decomposition of the materials. The temperature of decomposition decreases with the growing length of diamine molecules and achieves the lowest value (176 °C, 449 K) for the compound with 1,12-diaminododecane (the longest diamine among the studied ones) while the sample with 1,4-diaminobutane is the most stable one (up to around 284 °C, 557 K). The studied compounds also show odd-even separate trends concerning the decomposition temperature. The compounds with even diamines start to decompose at relatively higher temperatures than the ones belonging to the odd series.

Advancing membrane-associated protein docking with improved sampling and scoring in Rosetta.

The oligomerization of protein macromolecules on cell membranes plays a fundamental role in regulating cellular function. From modulating signal transduction to directing immune response, membrane proteins (MPs) play a crucial role in biological processes and are often the target of many pharmaceutical drugs. Despite their biological relevance, the challenges in experimental determination have hampered the structural availability of membrane proteins and their complexes. Computational docking provides a promising alternative to model membrane protein complex structures. Here, we present Rosetta-MPDock, a flexible transmembrane (TM) protein docking protocol that captures binding-induced conformational changes. Rosetta-MPDock samples large conformational ensembles of flexible monomers and docks them within an implicit membrane environment. We benchmarked this method on 29 TM-protein complexes of variable backbone flexibility. These complexes are classified based on the root-mean-square deviation between the unbound and bound states (RMSDUB) as: rigid (RMSDUB < 1.2 A;), moderately-flexible (1.2 A < RMSDUB < 2.2 A), and flexible targets (RMSDUB > 2.2 A). In a local docking scenario, i.e. with membrane protein partners starting ~10 A apart embedded in the membrane in their unbound conformations, Rosetta-MPDock successfully predicts the correct interface (success defined as achieving 3 near-native structures in the 5 top-ranked models) for 67% moderately flexible targets and 60% of the highly flexible targets, a substantial improvement from the existing membrane protein docking methods. Further, by integrating AlphaFold2-multimer for structure determination and using Rosetta-MPDock for docking and refinement, we demonstrate improved success rates over the benchmark targets from 64% to 73%. Rosetta-MPDock advances the capabilities for membrane protein complex structure prediction and modeling to tackle key biological questions and elucidate functional mechanisms in the membrane environment. The benchmark set and the code is available for public use at github.com/Graylab/MPDock.

First-Principles Computational Screening of Two-Dimensional Polar Materials for Photocatalytic Water Splitting.

The band gap constraint of the photocatalyst for overall water splitting limits the utilization of solar energy. A strategy to broaden the range of light absorption is employing a two-dimensional (2D) polar material as photocatalyst, benefiting from the deflection of the energy level due to their intrinsic internal electric field. Here, by using first-principles computational screening, we search for 2D polar semiconductors for photocatalytic water splitting from both ground- and excited-state perspectives. Applying a unique electronic structure model of polar materials, there are 13 photocatalyst candidates for the hydrogen evolution reaction (HER) and 8 candidates for the oxygen evolution reaction (OER) without barrier energies from the perspective of the ground-state free energy variation calculation. In particular, Cu2As4Cl2S3 and Cu2As4Br2S3 can catalyze HER and OER simultaneously, becoming promising photocatalysts for overall water splitting. Furthermore, by combining ground-state band structure calculations with excited-state charge distribution and transfer calculated by linear-response time-dependent density functional theory (LR-TDDFT) and time-dependent ab initio nonadiabatic molecular dynamics (NAMD), respectively, the rationality of the 2D polar material model has been manifested. The intrinsic built-in electric field promotes the separation of charge carriers while suppressing their recombination. Therefore, our computational work provides a high-throughput method to design high-performance photocatalysts for water splitting.

Numerical simulations of a stochastic dynamics leading to cascades and loss of regularity: Applications to fluid turbulence and generation of fractional Gaussian fields

Motivated by the modeling of the spatial structure of the velocity field of three-dimensional turbulent flows, and the phenomenology of cascade phenomena, a linear dynamics was recently proposed that can generate high velocity gradients from a smooth-in-space forcing term. It is based on a linear partial differential equation stirred by an additive random forcing term that is δ-correlated in time. The underlying proposed deterministic mechanism corresponds to a transport in Fourier space that aims to transfer energy injected at large scales towards small scales. The key role of the random forcing is to realize these transfers in a statistically homogeneous way. Whereas at finite times and positive viscosity the solutions are smooth, a loss of regularity is observed for the statistically stationary state in the inviscid limit. We present here simulations, based on finite volume methods in the Fourier domain and a splitting method in time, which are more accurate than the pseudospectral simulations. We show that our algorithm is able to reproduce accurately the expected local and statistical structure of the predicted solutions. We conduct numerical simulations in one, two, and three spatial dimensions, and we display the solutions both in physical and Fourier space. We additionally display key statistical quantities such as second-order structure functions and power spectral densities at various viscosities. Published by the American Physical Society 2024

Substructure-based topology optimization design method for passive constrained damping structures

Abstract This work presents a generalized substructure-based topology optimization method for passive constrained layer damping (PCLD) structures. Here, the model of PCLD structure is obtained by the Kirchhoff-Love thin plate formulation. And the whole structure is assumed to be composed of substructures with different yet connected scales and artificial lattice geometry features. Each substructure is condensed into a super-element to obtain the associated density-related matrices under the different geometry feature parameters. And the surrogate model for the stiffness and mass matrix of PCLD substructures with different densities has been particularly built. Using cubic spline interpolation, the derivatives of super-element matrices to the associated densities can be evaluated efficiently and accurately. The modal loss factor is defined as objective functions and topology optimization for the PCLD structures is formulated based on the model for PCLD plates which are described by combining the condensed substructures. Numerical examples under two lattice patterns of substructures and their corresponding physical tests show that the correctness and superiority of this substructure-based topology optimization approach for PCLD plates are verified.

Rerefinement of the crystal structure of BiF5

The crystal structure of bismuth pentafluoride, BiF5, was rerefined from single-crystal data. BiF5 crystallizes in the α-UF5 structure type in the form of colorless needles. In comparison with the previously reported crystal-structure model [Hebecker (1971). Z. Anorg. Allg. Chem. 384, 111–114], the lattice parameters and fractional atomic coordinates were determined to much higher precision and all atoms were refined anisotropically, leading to a significantly improved structure model. The Bi atom (site symmetry 4/m..) is surrounded by six F atoms in a distorted octahedral coordination environment. The [BiF6] octahedra are corner-linked to form infinite straight chains extending parallel to [001]. Density functional theory (DFT) calculations at the PBE0/TZVP level of theory were performed on the crystal structure of BiF5 to calculate its IR and Raman spectra. These are compared with experimental data.