Types Of Structures Research Articles

Enhanced magnetic refrigeration capacities of Er6FeSb2 by manganese substitution

Er6FeSb2 is a potential magnetic refrigeration material that can work at the liquid hydrogen temperature range. This work enhances the magnetic refrigeration performance of Er6Fe1-xMnxSb2 by Mn substitution. Mn doping increases the cell volume while maintaining the compound’s crystal structure type. It also results in an increase in the charge density distribution between Er1 and Fe/Mn. As the Mn content increases, the ferromagnetic exchange is enhanced, and the TC continuously increases. The Mn doping induces spin reorientation at low temperature, transforming compounds from traditional magnetocaloric effects to table-like magnetocaloric effects, greatly enlarge the cooling temperature range. When the content of Mn increases from x = 0 to x = 0.3, the δTFWHM increases from 26 K to 62 K, the −(ΔSM)max decreases from 12.1 J/(kg·K) to 5.9 J/(kg·K), and the RCP first increases and then decreases, reaching the maximum value of 435.0 J/kg at x = 0.2. This study opens a new path for the search of magnetic refrigeration material with large cooling temperature range.

Non-benzenoid N-aryl oxalamide: synthesis of troponyl-oxalamide peptides by Pd(II)-catalyzed C(sp3)-H functionalization of glycinamides.

Aryl oxalamides are constituents of various promising drug-like molecules. Their aryl groups are derived from the benzenoid aromatic moiety. However, non-benzenoid aromatic molecules, troponoids, are found in various bioactive natural products. It would be thought-provoking to explore non-benzenoid aryl oxalamide derivatives. This report describes the synthesis of N-troponyl-oxalamide peptides by Pd(II)-catalyzed C(sp3)-H functionalization of N-troponyl glycinate peptides. This is the first instance of β-hydride elimination at the palladium complex of N-troponyl glycinates that generates imine in situ, rendering the synthesis of oxalamides. Importantly, the crystal structures of representative oxalamide derivatives form distinctive foldameric structures, such as β-sheet type structures, owing to the presence of additional troponyl carbonyl groups. Hence, these non-benzenoid oxalamides are potential scaffolds for tuning the structure and function of N-troponyl peptides, which could provide innovative avenues of research in the development of emerging structural and functional peptides.

Chemical Epitaxy of Iridium Oxide on Tin Oxide Enhances Stability of Supported OER Catalyst.

Significantly reducing the iridium content in oxygen evolution reaction (OER) catalysts while maintaining high electrocatalytic activity and stability is a key priority in the development of large-scale proton exchange membrane (PEM) electrolyzers. In practical catalysts, this is usually achieved by depositing thin layers of iridium oxide on a dimensionally stable metal oxide support material that reduces the volumetric packing density of iridium in the electrode assembly. By comparing two support materials with different structure types, it is shown that the chemical nature of the metal oxide support can have a strong influence on the crystallization of the iridium oxide phase and the direction of crystal growth. Epitaxial growth of crystalline IrO2 is achieved on the isostructural support material SnO2, both of which have a rutile structure with very similar lattice constants. Crystallization of amorphous IrOx on an SnO2 substrate results in interconnected, ultrasmall IrO2 crystallites that grow along the surface and are firmly anchored to the substrate. Thereby, the IrO2 phase enables excellent conductivity and remarkable stability of the catalyst at higher overpotentials and current densities at a very low Ir content of only 14 at%. The chemical epitaxy described here opens new horizons for the optimization of conductivity, activity and stability of electrocatalysts and the development of other epitaxial materials systems.

Bending fatigue performance of three‐dimensional woven composites—A review

AbstractThree‐dimensional woven composites (3DWCs) are gradually used in marine, transportation, military, and other applications owing to their high interlayer properties, load‐bearing capacity, and good near‐net‐shape forming abilities. 3DWCs are often subjected to bending fatigue loads, which negatively affect the lives of structural parts. In this review, typical types of preform structures and their evolution characteristics are described, and the micro‐modeling methods for 3DWCs are discussed. The effect of the warp yarn paths on the bending properties and the preform structure on the bending fatigue properties of 3DWCs are summarized, and the application and current status of microstructural models in the study of bending fatigue properties are summarized. In addition, the bending fatigue mechanical properties, damage evolution process, and modes of failure in 3DWCs are discussed. The study status and development of the fatigue life models of the laminated composites and 3DWCs are summarized, and future research work is prospected. This review may be beneficial to preform structural design and contribute to the study bending fatigue properties of 3DWCs.Highlights The microstructural modeling methods for 3DWCs. Types and variation patterns of 3D woven preform structures are described. Effects of the structure on the bending performance are discussed. Bending fatigue properties of 3DWCs are summarized. The development trends of predicting the lifespans of composites.

Strain phase equilibria and phase‐field method of ferroelectric polydomain: A case study of monoclinic KxNa1 − xNbO3 thin films

AbstractKnowledge of the thermodynamic equilibria and domain structures of ferroelectrics is critical to establishing their structure–property relationships that underpin their applications from piezoelectric devices to nonlinear optics. Here, we establish the strain condition for strain phase separation and polydomain formation and analytically predict the corresponding domain volume fractions and wall orientations of, relatively low symmetry and theoretically more challenging, monoclinic ferroelectric thin films by integrating thermodynamics of ferroelectrics, strain phase equilibria theory, microelasticity, and phase‐field method. Using monoclinic KxNa1 − xNbO3(0.5 < x < 1.0) thin films as a model system, we establish the polydomain strain–strain phase diagrams, from which we identify two types of monoclinic polydomain structures. The analytically predicted strain conditions of formation, domain volume fractions, and domain wall orientations for the two polydomain structures are consistent with phase‐field simulations and in good agreement with experimental results in the literature. The present study demonstrates a general, powerful analytical theoretical framework to predict the strain phase equilibria and domain wall orientations of polydomain structures applicable to both high‐ and low‐symmetry ferroelectrics and provide fundamental insights into the equilibrium domain structures of ferroelectric KxNa1 − xNbO3 thin films that are of technology relevance for lead‐free dielectric and piezoelectric applications.

Thallium-Fluorides Revisited: Crystal Chemistry of TlHF2, Tl2[MF6]·2TlF, and Tl2[MF6]·TlCl (M = Si and Ge).

Although the formation of thallium hydrogen fluorides TlHxFx+1 (x = 1, 1.5, 2, 3, 5, 6.5, and 7) from TlF and HF was reported in the 1970s, little is known about the corresponding crystal structures. To shed light on the crystal chemistry of the thallium fluorides, we reinvestigated the structure of α-TlHF2, which was obtained by crystallization of TlF from 50% HF at room temperature. We disclose that β-TlHF2 is isostructural with α-MHF2 (M = K, Rb, and Cs), γ-TlHF2 is isostructural with β-MHF2 (M = K and Rb), whereas α-TlHF2 crystallizes in an unusual structure type. During the reaction of TlHF2 with the glass of the microscope slide, crystals of the previously unknown compound Tl2[SiF6]·2TlF were formed. We disclose that the related Tl2[GeF6]·2TlF can be obtained by the crystallization of stoichiometric amounts of Tl2[GeF6] with TlF from water at room temperature. The crystal structures of α-TlHF2, Tl2[SiF6]·2TlF, Tl2[SiF6]·TlCl, Tl2[GeF6]·2TlF, Tl2[GeF6]·TlCl, and Tl2[GeF6] were determined by single-crystal X-ray diffraction analysis. The crystal structures of α-TlF and Tl2[SiF6]·xTlF (x = 0, 1) were redetermined at low temperatures.

A High–Throughput Molecular Dynamics Study for the Modeling of Cryogenic Solid Formation

To predict the favorable thermodynamical conditions and characterize cryogenic pellet formations for applications in nuclear fusion reactors, a high–throughput molecular dynamics study based on a unified framework to simulate the growth process of cryogenic solids (molecular deuterium, neon, argon) under gas pressure have been designed. These elements are used in fusion nuclear plants as fuel materials and to reduce the damage risks for the plasma-facing components in case of a plasma disruption. The unified framework is based on the use of workflows that permit management in HPC facilities, the submission of a massive number of molecular dynamics simulations, and handle huge amounts of data. This simplifies a variety of operations for the user, allowing for significant time savings and efficient organization of the generated data. This approach permits the use of large-scale parallel simulations on supercomputers to reproduce the solid–gas equilibrium curves of cryogenic solids like molecular deuterium, neon, and argon, and to analyze and characterize the reconstructed solid phase in terms of the separation between initial and reconstructed solid slabs, the smoothness of the free surfaces and type of the crystal structure. These properties represent good indicators for the quality of the final materials and provide effective indications regarding the optimal thermodynamical conditions of the growing process.

Formation mechanism and evolution of flow patterns for thermal convection in an inner cylinder-heated annular pool

In this paper, a set of numerical simulations were carried out to analyze the evolution and formation mechanism of various flow patterns for thermal convection in inner cylinder-heated annular pools at different depths. The results show that the basic flow bifurcates into the second type of hydrothermal waves, standing waves, petal-like structures, and spoke patterns after the flow destabilization. The formation mechanisms of these four flow patterns are all due to the lag in phase between temperature and velocity fluctuations. The reduction in surface azimuthal temperature fluctuation causes the second type of hydrothermal waves to bifurcate into standing waves. The bifurcation from standing waves to petal-like structures is due to the amplitude of azimuthal velocity fluctuation on the free surface being one order of magnitude smaller than that of radial velocity fluctuation. The bifurcation from petal-like structures to spoke patterns is because basic flow varies as the depth rises. Unlike the second type of hydrothermal waves, for standing waves, petal-like structures, and spoke patterns, the temperature fluctuation on different horizontal planes is different. Besides, for standing waves, the periodical variation process of the flow field depends on the azimuthal position.

The Strike-Slip Fault System and Its Influence on Hydrocarbon Accumulation in the Gudong Area of the Zhanhua Depression, Bohai Bay Basin

The Gudong area contains abundant petroleum resources. Previous studies have mainly focused on the extension structure in this area, with its strike-slip characteristics remaining poorly understood. In this study, the geometry of the strike-slip faults in the Gudong area was investigated using high-resolution 3D seismic reflection and drilling data, as were their associated releasing and restraining structures. Based on the profile’s flower structure and the plane’s horsetail splay pattern, the Gudong fault in the study area can be characterized as a dextral strike-slip. Three types of strike-slip fault-associated structures can be identified in the study area: (a) a restraining bend occurring in the right-stepping area of the S-shaped Gudong strike-slip fault, (b) a restraining bend identified in the left-stepping, overlapping zone of the Gudong and Kendong faults, and (c) a releasing bend seen in the extensional horsetail splay structure at the southern end of the Gudong fault. The restraining stress induced the formation of a fault-related open anticline, which led to a significant increase in fault sealing efficiency, thereby preserving an estimated 75.479231 million tons of oil and 15.28317145 billion cubic meters of gas. Conversely, releasing transtensional stress has compromised the effectiveness of the traps, preventing hydrocarbon retention. Consequently, oil and gas have migrated upward along the horsetail faults to the top of Cenozoic formations and have then dispersed.

Optimization of tuned mass dampers – minimization of potential energy of elastic deformation

A tuned mass damper (TMD) optimization can be performed under various assumptions and objectives. All the variables of the optimization, such as structural model, performance index and load type affect the optimal parameters of the TMD. This paper presents a new optimization method that implements straightforward performance index and allows taking load spectral characteristics into account. Thanks to the usage of modal coordinates, the method allows fast numerical optimization of TMD attached to large or complicated structures with numerous degrees of freedom. One of the complicated tasks while optimizing TMD is the choice of a performance index. In this paper, the mean value of potential energy stored in the elastic deformation of a structure under periodic load serves as a performance index, which leads to a low numerical complexity task if the optimization is performed in the frequency domain. The new method also allows a simple inclusion of load spectral characteristics and permits TMD optimization for any loading spectral range. When applied to a structure with a single degree of freedom, this method leads to H2 optimization in the case of white noise excitation. However, it is applicable to multiple degrees of freedom structures with single or multiple TMDs and any given load. The paper also presents several examples of numerical optimization of the TMD attached to both single and multiple degrees of freedom structures under various loads, including white noise excitation, pedestrian load, and earthquake strong motion.

Influence of forging pretreatments on microstructure evolution and surface roughness of Al 6061 alloy

Achieving ultra-smooth surfaces is the goal of aluminum optical manufacturing. Under certain processing conditions, improving the microstructure of aluminum and understanding its relationship with surface roughness requires systematic study. The grain structure and various types of second-phase particles are of paramount importance. This study analyzed the microstructure of 6061 alloy after undergoing severe plastic deformation under various processing conditions followed by T6 homogenization heat treatment. Utilizing a white light interferometer, a comparative analysis of the surface roughness was conducted on specimens that underwent single-point diamond turning to achieve a mirror finish. The assessment of surface roughness on machined surfaces is solely based on white light interferometry. The analysis and discussion focus on the effects of phases (causing scratches and voids), the grains and grain boundaries. Experimental findings signify: the grain size, grain boundary and residual second phase can both influence the surface quality, the increase in deformation temperature and accumulated strain both facilitate the dissolution and fragmentation of the secondary phases. However, they also contribute to some extent to grain growth, resulting in a minimum secondary phase area fraction of 0.87% and grain sizes reaching 147.8 μm. Subsequent heat treatments, while effective in reducing the negative impact of the phases, reveal noticeable step-like structures affecting the quality of surface roughness, with the lowest obtained Ra value being 0.8 nm. A proposed pretreatment method in cleaner ingot processing with lower alloy element content addresses the trade-off between reducing phases and controlling grain growth, aiming to achieve improved surface roughness, promoting the application of polycrystalline aluminum alloys in the field of optics manufacturing.

Clinical efficacy and immune response of neoadjuvant camrelizumab plus chemotherapy in resectable locally advanced oesophageal squamous cell carcinoma: a phase 2 trial

BackgroundNeoadjuvant immunotherapy is under intensive investigation for esophageal squamous cell carcinoma (ESCC). This study assesses the efficacy and immune response of neoadjuvant immunochemotherapy (nICT) in ESCC.MethodsIn this phase II trial (ChiCTR2100045722), locally advanced ESCC patients receiving nICT were enrolled. The primary endpoint was the pathological complete response (pCR) rate. Multiplexed immunofluorescence, RNA-seq and TCR-seq were conducted to explore the immune response underlying nICT.ResultsTotally 42 patients were enrolled, achieving a 27.0% pCR rate. The 1-year, 2-year DFS and OS rates were 89.2%, 64.4% and 97.3%, 89.2%, respectively. RNA-seq analysis highlighted T-cell activation as the most significantly enriched pathway. The tumour immune microenvironment (TIME) was characterised by high CD4, CD8, Foxp3, and PD-L1 levels, associating with better pathological regression (TRS0/1). TIME was categorised into immune-infiltrating, immune-tolerant, and immune-desert types. Notably, the immune-infiltrating type and tertiary lymphoid structures correlated with improved outcomes. In the context of nICT, TIM-3 negatively influenced treatment efficacy, while elevated TIGIT/PD-1 expression post-nICT correlated positively with CD8+ T cell levels. TCR-seq identified three TCR rearrangements, underscoring the specificity of T-cell responses.ConclusionsNeoadjuvant camrelizumab plus chemotherapy is effective for locally advanced, resectable ESCC, eliciting profound immune response that closely associated with clinical outcomes.

P-type nickel cobalt oxide synthetized by chemical bath deposition to applications on thin film transistors

This work studies nickel-cobalt oxide (NiCo2O4) thin films synthesized via chemical bath deposition for potential application as p-type active layers in electronic devices. X-ray photoemission electron spectroscopy (XPS) confirms the synthesis of a ternary compound with a stoichiometry of Ni1.04Co1.96O4. The thin film sample exhibiting the closest stoichiometry to the ternary compound has a thickness of approximately 50 nm. Scanning Electron Microscopy (SEM) micrographs indicate an increase in surface porous size corresponding to higher nickel concentrations in the ternary compound. All synthesized NiCo2O4 thin films demonstrate p-type behavior. The lowest resistivity film had a majority carrier concentration of 1×1020 1/cm3, a mobility value of 0.1 cm2/V·s, and a resistivity of 0.1 Ω cm. X-ray diffraction (XRD) studies reveal that the thin films have a type of spinel cubic structure for the phase NiCo2O4. Characteristic spinel bands are observed in the UV–Vis transmittance spectra, and the energy bandgaps of the Ni1.04Co1.96O4 film are estimated to be approximately 3.41 and 2.19 eV using the Tauc method. The thin film with the lowest resistivity was used as an active layer to fabricate a thin-film transistor, displaying typical output curves of a p-channel transistor.

Higher-order multi-scale physics-informed neural network (HOMS-PINN) method and its convergence analysis for solving elastic problems of authentic composite materials

The limitations of prohibitive computation and Frequency Principle remain difficult for deep learning methods to effectively resolve multi-scale problems. In this work, a novel higher-order multi-scale physics-informed neural network (HOMS-PINN) framework is developed to compute the elastic problems of authentic composite materials with strongly discontinuous and high-contrast material parameters, which inherits the advantages of higher-order multi-scale method and physics-informed neural network, and halves the computational expense remarkably in comparison with direct PINN simulation. In the numerical framework of HOMS-PINN method, two types of network structures including single neural networks and independent neural networks are designed to mesh-free solve lower-order and higher-order microscopic unit cell (UC) functions, and macroscopic homogenization equations of multi-scale composites, which are then assembled into higher-order multi-scale solutions for multi-scale elastic problems by using automatic differentiation technology. Moreover, transfer learning is introduced to extend HOMS-PINN framework accelerating simulation of multi-scale elastic problems for composite materials with high-contrast mechanical parameters. Furthermore, the error estimate of the proposed HOMS-PINN method is demonstrated under some assumptions. Finally, numerous numerical experiments including high-contrast, multi-inclusion and three-dimensional composites are presented to validate the accuracy and effectiveness of HOMS-PINN method, especially for accurately capturing the sharply oscillatory behaviors in micro-scale. This study offers a robust HOMS-PINN computational framework that enables the simulation and analysis of large-scale mechanical problems of authentic composite materials.

Multi-target anti-diabetic styrylpyrones from Phellinus igniarius: Inhibition of α-glucosidase, protein glycation, and oxidative stress

Bioactivity screening revealed that the EtOAc extract from the culture broth of Phellinus igniarius SY489 exhibited remarkable α-glucosidase inhibitory activity, with an IC50 value of 1.92 μg/mL. Activity- and ultraviolet (UV) profile-guided isolation led to the discovery of four anti-diabetic styrylpyrones (1–4), including two novel compounds, phelignidins A (1) and B (2). Compounds 1 and 2 represent a rare structural type of styrylpyrone dimer, in which one of the pyrone moieties exists in an open-ring state. The absolute configurations of the new compounds 1 and 2, as well as the previously unresolved compound 3, were established. Compounds 1–4 were effective in α-glucosidase inhibition, anti-glycation, and antioxidant assays, surpassing or being comparable to the positive control drugs, with minimal cytotoxicity. Furthermore, studies on α-glucosidase inhibition mechanisms suggested that these compounds interact with α-glucosidase at a single binding site, causing secondary structure unfolding and exerting inhibitory activity via a mixed-type mechanism. These results provide an important basis for developing novel, low-toxicity, multi-target anti-diabetic drugs from edible and medicinal fungi.

A literature review of allergen properties in fish collagen and its derivative products

Fish are generally categorized as allergens that cause reactions mediated by Immunoglobulin E (IgE). Fish collagen is one of the causes of allergic reactions, ranging from mild symptoms such as nausea and itching to severe symptoms such as anaphylaxis across all ages. Previous research has not specifically or comprehensively explained the characteristics of fish collagen and its derivatives as allergens. This study aims to address this gap by explaining the properties, contributing factors, and potential hazards of fish collagen and its derivatives as allergens. This research employed a literature review summarizing several main studies to produce comprehensive findings. The structure of collagen, contaminant allergens, and fish type can affect the allergenicity of fish collagen. Processing methods, such as heating, acid or enzyme treatment, and washing, can determine allergenicity. The structure of fish collagen can change upon heating, but its allergenicity cannot be reduced. Fish collagen is also known to have good resistance to enzymes; therefore, it can easily bind to immune cells. Another factor was age, in which adults had a greater frequency of IgE binding to fish collagen than did children and adolescents. They were included as potential allergens based on research results and existing data regarding allergy cases and their potential hazards. Therefore, there is a need for further research on allergies to fish collagen and its derivatives, especially in countries that do not require the inclusion of allergens where food safety matters.

Sound transmission loss and bending properties of sandwich structures based on triply periodic minimal surfaces

Four types of triply periodic minimal surfaces sandwich structures (TPMS-SS), namely, G-SS, D-SS, D1-SS, and IWP-SS, have been proposed. The bending properties were evaluated by experiments and numerical simulations, and their sound insulation performance was investigated using theoretical, numerical and experimental methods. Firstly, the bending performance of four TPMS-SS was compared. Then, the acoustic vibration control equation of TPMS-SS was established and the theoretical solution for the sound transmission loss (STL) was derived based on Reissner's theory combined with the fluid-solid coupling condition. Next, experimental study was conducted on the STL performance of TPMS-SS using the impedance tube method, and the numerical model was verified using theoretical and experimental results. Finally, parametric studies were carried out to investigate the effects of parameters such as relative density (RD), panel thickness (hf), and sound incidence elevation angle (φ), as well as the type of structure, on the STL performance. The results show that TPMS-SSs can achieve >30 dB of STL in the frequency range of 1 Hz to 10 kHz. The STL value increases with relative density (RD), panel thickness (hf), and sound incident elevation angle (φ), while the location of the dips in the STL curves is affected by relative density and panel thickness. G-SS has the best bending performance, while D1-SS has the best acoustic performance. The results could be used for the optimization design of lightweight sandwich structures.

Large-scale analysis of the PAC domain structure of arogenate dehydratases reveals their evolutionary patterns in angiosperms

Arogenate dehydratase (ADT) is the key limiting enzyme of plant phenylalanine biosynthesis, but some ADTs display a prephenate decarboxylase/dehydratase activity-conferring (PAC) domain. The genome resources of 70 species were employed to identify genes and outline their characteristics, especially the number and type of PAC domain structures. We obtained 522 ADTs, and their size, exon number, amino acid number and putative protein isoelectric point greatly varied from 306 to 2520 bp, 1 to 15, 101 to 839 and 4.37 to 11.18, respectively. We classified the ADTs into Class α (without a PAC domain) (115, 22.0 %), β (with a type I PAC domain) (244, 46.7 %) and γ (with a type II PAC domain) (163, 31.2 %), and their distribution frequencies exhibited large differences among various branches of angiosperms. We found that Class γ members are more conserved than Class β members, although they commonly experienced multiple duplication events and strong purifying selection, which resulted in a small number, and the putative origin order was from Class α to β and then to γ. In addition, the co-occurrence of both Class β and γ members could ensure the survival of angiosperms, while their optimized composition and strategically intertwined regulation may facilitate core eudicot success.

Simulation of the Dynamic Impact of High-Speed Rolling Stock on Buried Structures of the Tunnel Type

Simulation of the Dynamic Impact of High-Speed Rolling Stock on Buried Structures of the Tunnel Type

Distinct phylogeographic and population genetic patterns of decapod species across Mediterranean biogeographic barriers

Abstract The Mediterranean Sea is a semi-enclosed oceanic basin that communicates with the Atlantic Ocean and can be subdivided into seven geographical regions. It is considered a hotspot of biodiversity and is characterised by high rates of endemism. Over the past decades, many studies showed the presence of potential geographical breaks both across the Atlanto-Mediterranean transition and within the Mediterranean Sea. These investigations led to the identification of three distinct types of population genetic structures: (1) populations characterized by panmixia; (2) Atlanto-Mediterranean geographical partitioning; and (3) possible further subdivision between East and West Mediterranean basins. In this review, mainly focused on Christoph Schubart’s works and interests, we summarize the different patterns of gene flows across the Atlanto-Mediterranean transition and within the Mediterranean Sea, recorded for decapod species living in littoral zones. Although some species share similar biological traits, larval dispersal mechanisms and habitat preferences, differences in their phylogeographic and population genetic structures do emerge. These findings confirm the complex nature of gene flows across the Atlanto-Mediterranean transition and within the Mediterranean basin and how difficult it is to achieve a generalised picture of the phylogeographical patterns of Atlantic-Mediterranean species.