Theory for Charge Density Wave and Orbital-Flux State in Antiferromagnetic Kagome Metal FeGe

We theoretically study the charge order and orbital magnetic properties of a new type of antiferromagnetic kagome metal FeGe.Based on first-principles density functional theory calculations,we study the electronic structures,Fermi-surface quantum fluctuations,as well as phonon properties of the antiferromagnetic kagome metal FeGe.It is found that charge density wave emerges in such a system due to a subtle cooperation between electron-electron interactions and electron–phonon couplings,which gives rise to an unusual scenario of interaction-triggered phonon instabilities,and eventually yields a charge density wave(CDW)state.We further show that,in the CDW phase,the ground-state current density distribution exhibits an intriguing star-of-David pattern,leading to flux density modulation.The orbital fluxes(or current loops)in this system emerge as a result of the subtle interplay between magnetism,lattice geometries,charge order,and spin-orbit coupling(SOC),which can be described by a simple,yet universal,tight-binding theory including a Kane-Mele-type SOC term and a magnetic exchange interaction.We further study the origin of the peculiar step-edge states in FeGe,which sheds light on the topological properties and correlation effects in this new type of kagome antiferromagnetic material.

Simultaneous control of ferromagnetism and ferroelasticity by oxygen octahedral backbone stretching

Coexistence of ferromagnetism and ferroelasticity in a single material is an intriguing phenomenon,but has been rarely found.Here we studied both the ferromagnetism and ferroelasticity in a group of LaCoO3 films with systematically tuned atomic structures.We found that all films exhibit ferroelastic domains with four-fold symmetry and the larger domain size(higher elasticity)is always accompanied by stronger ferromagnetism.We performed synchrotron x-ray diffraction studies to investigate the backbone structure of the CoO6 octahedra,and found that both the ferromagnetism and the elasticity are simultaneously enhanced when the in-plane Co–O–Co bond angles are straightened.Therefore the study demonstrates the inextricable correlation between the ferromagnetism and ferroelasticity mediated through the octahedral backbone structure,which may open up new possibilities to develop multifunctional materials.

Superplasticized vs. Conventional Concrete: A Comparative Review

The global awareness and utilization of superplasticizers (SPs) in concrete have significantly contributed to developing resilient and sustainable infrastructure. Despite this, many developing nations face limited adoption of SPs in construction practices due to a lack of knowledge. This study provides a concise overview of concrete’s mechanical and durability properties, comparing formulations with and without superplasticizers. The focus is on compressive and flexural strengths, modulus of elasticity, water sorptivity, and chloride penetration. The results underscore the considerable improvement in both mechanical and durability properties when SPs are incorporated. The study recommends the widespread use of SPs, particularly in developing countries, to enhance the longevity of concrete structures.

Laser-Heated Diamond-Anvil Cell (LHDAC) in Materials Science Research

Laser-heated diamond-anvil cell (LHDAC) is emerging as the most suitable, economical and versatile tool for the measurement of a large spectrum of physical properties of materials under extreme pressure and temperature conditions. In this review, the recent developments in the instrumentation, pressure and temperature measurement techniques, results of experimental investigations from the literature were discussed. Also, the future scope of the technique in various avenues of science was explored.

Nanoscale materials transformations revealed by liquid phase TEM

Nanoscale materials often undergo structural,morphological,or chemical changes,especially in solution processes,where heterogeneity and defects may significantly impact the transformation pathways.Liquid phase transmission electron microscopy(TEM),allowing us to track dynamic transformations of individual nanoparticles,has become a powerful platform to reveal nanoscale materials transformation pathways and address challenging issues that are hard to approach by other methods.With the development of modern liquid cells,implementing advanced imaging and image analysis methods,and strategically exploring diverse systems,significant advances have been made in liquid phase TEM,including improved high-resolution imaging through liquids at the atomic level and remarkable capabilities in handling complex systems and reactions.In the past more than a decade,we spent much effort in developing and applying liquid phase TEM to elucidate how atomic level heterogeneity and defects impact various physicochemical processes in liquids,such as growth,self-assembly of nanoparticles,etching/corrosion,electrodeposition of alkali metals,catalyst restructuring during reactions,and so on.This article provides a brief review of the liquid phase TEM study of nanoscale materials transformations,focusing on the growth of nanomaterials with distinct shape/hierarchical structures,such as one-dimensional(1D)growth by nanoparticle attachment,two-dimensional(2D)growth with nanoparticles as intermediates,core-shell structure ripening,solid-liquid interfaces including those in batteries and electrocatalysis,highlighting the impacts of heterogeneity and defects on broad nanoscale transformation pathways.

高温氧化时Al_2O_3/FeAl界面孔洞形成过程的分析

合金高温氧化时在氧化膜/合金界面处常出现孔洞,显著地削弱氧化膜的黏附力.研究了1000℃氧化后Fe—40％Al合金/氧化膜处孔洞的生成过程,并测定孔洞数量与体积随氧化时间的变化.将经不同时间氧化试样表面形成的氧化膜揭去后,用扫描电子显微镜和原子力显微镜测定界面处孔洞的大小和深度.同时基于氧化过程中产生的空位全部聚集形成孔洞的考虑,计算了形成孔洞的总量.把实验结果与理论计算进行比较,讨论了氧化膜/合金界面处孔洞形成的机制.

Phase selection of ternary intermetallic compounds during solidification of high zinc magnesium alloy

The phase selection of ternary intermetallic compound τphase (Mg32(Al, Zn)49 ) and φ phase (Al2Mg5Zn2) in high zinc magnesium alloys was studied by using scanning electron microscope, X-ray diffractometer and differential scanning calorimeter, etc. The results indicate that, when adding element Si in Mg-8Zn-4Al-0.3Mn (ZA84) alloy, φ phase is promoted, whereas τ phase is inhibited. The Chinese script-type Mg2Si and matrix microstructure are greatly refined, the formation of τ phase is facilitated and φ phase is restrained when modifier Al-AlP master alloy is added in ZA84 alloy containing Si. The kinetics study of phase selection indicates that there is a critical degree of undercooling of the melt. If the undercooling exceeds the critical value, τ phase preferentially forms while φ phase is restrained; otherwise, φ phase preferentially forms while τ phase is restrained.

Impurity Segregation at TGO/Bondcoat Interfaces and Its Effect on TGO Adherence

Impurity segregation at the interfaces between thermally grown aluminum oxide and a few coatings deposited on single crystal Ni-based superalloys are reviewed.Results are compared with studies made at oxide/metal interfaces formed on model Al_2O_3-forming alloys.The coatings were NiPtAl on CMSX4 or AM1 with two different bulk sulfur contents,and NiCoCrAlY on PWA1484.Auger electron microscopy was used to study the chemistry at the TGO/coating interface after portions of the oxide scale were removed in ultra high vacuum by scratching the oxidized sample.The extent of oxide spallation in relation to the scratch width was utilized to evaluate the interfacial strength,which was then related to the interface chemistry,particular its sulfur level.Results show strong relationship between sulfur segregation and the alloy substrate composition.This relationship is discussed in terms of the effects of Pt,Hf,Y and Cr and the alloy sulfur content.

Fabrication and characterization of SmO_(0.7)F_(0.2)FeAs bulk with a transition temperature of 56.5 K

The superconductivity of iron-based superconductor SmO 0.7 F 0.2 FeAs was investigated. The SmO 0.7 F 0.2 FeAs sample was prepared by the two-step solid-state reaction method. The onset resistivity transition temperature is as high as 56.5 K. X-ray diffraction （XRD） results show that the lattice parameters a and c are 0.39261 and 0.84751 nm, respectively. Furthermore, the global J c was more than 2.3 × 10 5 A/cm 2 at T = 10 K and H = 9 T, which was calculated by the formula of J c = 20ΔM/[a（1-a/（3b））]. The upper critical fields, H c2 ≈ 256 T （T = 0 K）, was determined according to the Werthamer-Helfand-Hohenberg formula, indicating that the SmO 0.7 F 0.2 FeAs was a superconductor with a very promising application.

Mechanical properties and microstructural evolution of ultrafine grained zircaloy-4 processed through multiaxial forging at cryogenic temperature

The mechanical properties and microstructural evolution of zircaloy-4 subjected to cumulative strains of 1.48,2.96,4.44 and 5.91 through multiaxial forging（MAF） at cryogenic temperature（77 K） were investigated.The mechanical properties of the MAF treated alloy were measured through universal tensile testing and Vickers hardness testing equipment.The zircaloy-4 deformed up to a cumulative strain of 5.91 showed improvement in both ultimate tensile strength and hardness from 474 MPa to 717 MPa and from HV 190 to HV 238,respectively,as compared with the as-received alloy.However,there was a noticeable decrement in ductility（from 18%to 3.5%） due to the low strain hardening ability of deformed zircaloy-4.The improvement in strength and hardness of the deformed alloy is attributed to the grain size effect and higher dislocation density generated during multiaxial forging.The microstructural evolutions of deformed samples were characterized by optical microscopy and transmission electron microscopy（TEM）.The evolved microstructure at a cumulative strain of 5.91 obtained after MAF up to 12 cycles depicted the formation of ultrafine grains with an average size of 150-250 nm.

Recent Advances of Graphitic Carbon Nitride-Based Structures and Applications in Catalyst, Sensing, Imaging, and LEDs

The graphitic carbon nitride(g-C_3N_4) which is a two-dimensional conjugated polymer has drawn broad interdisciplinary attention as a low-cost, metal-free, and visible-light-responsive photocatalyst in the area of environmental remediation. The g-C_3N_4-based materials have excellent electronic band structures, electron-rich properties, basic surface functionalities, high physicochemical stabilities and are ‘‘earth-abundant.'' This review summarizes the latest progress related to the design and construction of g-C_3N_4-based materials and their applications including catalysis, sensing,imaging, and white-light-emitting diodes. An outlook on possible further developments in g-C_3N_4-based research for emerging properties and applications is also included.

Host–Guest Molecular Recognition at Liquid–Liquid Interfaces

Host–guest molecular recognition at the liquid–liquid interface endows the interface with unique properties,including stimuli-responsiveness and self-regulation,due to the dynamic and reversible nature of non-covalent interactions.Increasing research efforts have been put into the preparation of supramolecular interfacial systems such as films and microcapsules by integrating functional components(e.g.,colloidal particles,polymers)at the interface,providing tremendous opportunities in the areas of encapsulation,delivery vehicles,and biphasic reaction systems.In this review,we summarize recent progress in supramolecular interfacial systems assembled by host–guest chemistry,and provide an overview of the fabrication process,functions,and promising applications of the resultant constructs.

Some recent advances in ab initio calculations of nonradiative decay rates of point defects in semiconductors

In this short review,we discuss a few recent advances in calculating the nonradiative decay rates for point defects in semiconductors.We briefly review the debates and connections of using different formalisms to calculate the multi-phonon processes.We connect Dr.Huang's formula with Marcus theory formula in the high temperature limit,and point out that Huang's formula provide an analytical expression for the phonon induced electron coupling constant in the Marcus theory formula.We also discussed the validity of 1D formula in dealing with the electron transition processes,and practical ways to correct the anharmonic effects.

液体树脂灌注成型技术(LRI)的数值建模计算研究

近几年在树脂膜渗透成型工艺(RFI)的基础上开发出了一种新型的航空复合材料制造工艺:液体树脂灌注成型工艺(LRI,Liquid Resin Infusion)。由于LRI是在一个真空膜下进行的,它不需要特殊的模具,所以大大降低了制造成本,并且用这种工艺可以制出大而厚的复杂部件,但是这也使得我们很难了解到整个工艺过程中内部参数的变化情况。为了指导实际的制造工艺,优化制造方案和参数,并减少制造缺陷,开发和运用有效的数值计算模型就变的非常的必要。最近Celle等人利用有限元方法(FEM)开发出了一种有关LRI的基础数值模型[4,5],本文将要介绍在这种基础模型上开发出的对LRI的数值建模计算方法和它的应用,并与实验结果进行对比和讨论。结果表明:本文所做的数值建模计算结果与实验结果有着较好的一致性,能较为有效地对LRI成型工艺进行模拟计算。

Role of activation energies of individual phases in two-phase range on constitutive equation of Zr-2.5Nb-0.5Cu alloy

Dominant phase during hot deformation in the two-phase region of Zr-2.5Nb-0.5Cu （ZNC） alloy was studied using activation energy calculation of individual phases. Thermo-mechanical compression tests were performed on a two-phase ZNC alloy in the temperature range of 700-925 ℃ and strain rate range of 10-2-10 s-l, Flow stress data of the single phase were extrapolated in the two-phase range to calculate flow stress data of individual phases. Activation energies of individual phases were then calculated using calculated flow stress data in the two-phase range, Comparison of activation energies revealed that a phase is the dominant phase （deformation controlling phase） in the two-phase range. Constitutive equations were also developed on the basis of the deformation temperature range （or according to phases present） using a sine-hyperbolic type constitutive equation. The statistical analysis revealed that the constitutive equation developed for a particular phase showed good agreement with the experimental results in terms of correlation coefficient （R） and average absolute relative error （AARE）.

DEVELOPMENT OF A CATALYST FOR SOLUTION OF POLY(VINYL ALCOHOL) IN NON-AQUEOUS MEDIUM

Chloro ethane dimethyl sulfoxide,C_2H_5Cl·DMSO(ECI·DMSO)was prepared by interaction of acrylic acid with conc.Hydrochloric acid in dimethyl sulfoxide(DMSO)and subsequent decarboxylation with H_2O_2 solution.The formation of the compound was confirmed by spectral and analytical methods;the molecular weight was determined by cryoscopic method.The solubility of poly(vinyl alcohol)(PVA)in different solvents or mixed solvents at 40℃,50℃and 60℃temperature in the presence of 0.01% of EC1·-DMSO was determined.It tu...

Magnetic properties of Sn-substituted Ni-Zn ferrites synthesized from nano-sized powders of NiO, ZnO, Fe_2O_3, and SnO_2

A series of Ni_（0.6-x/2）Zn_（0.4-x/2）Sn_xFe_2O_4（x = 0.0, 0.05, 0.1, 0.15, 0.2, and 0.3）（NZSFO） ferrite composities have been synthesized from nano powders using a standard solid state reaction technique. The spinel cubic structure of the investigated samples has been confirmed by x-ray diffraction（XRD）. The magnetic properties such as saturation magnetization（M_s）,remanent magnetization（M_r）, coercive field（H_c）, and Bohr magneton（μ） are calculated from the hysteresis loops. The value of M_s is found to decrease with increasing Sn content in the samples. This change is successfully explained by the variation of A-B interaction strength due to Sn substitution in different sites. The compositional stability and quality of the prepared ferrite composites have also been endorsed by the fairly constant initial permeability（μ＇） over a wide range of frequency. The decreasing trend of μ＇ with increasing Sn content has been observed. Curie temperature TChas been found to increase with the increase in Sn content. A wide spread frequency utility zone indicates that the NZSFO can be considered as a good candidate for use in broadband pulse transformers and wide band read-write heads for video recording. The composition of x = 0.05 shows unusual results and the possible reason is also mentioned with the established formalism.

Revealing the working mechanism of a multi-functional block copolymer binder for lithium-sulfur batteries

The lithium-sulfur(Li-S)battery is one of the most promising substitutes for current energy storage systems because of its low cost,high theoretical capacity,and high energy density.However,the high solubility of intermediate products(i.e.,lithium polysulfides)and the resultant shuttle effect lead to rapidly fading capacity and a low coulombic efficiency,which hinder the practical application of Li-S batteries.In this study,block copolymers are constructed with both an ethylene oxide unit and a styrene unit and then used as binders for Li-S batteries.Electrochemical performance improvements are attributed to the synergistic effects contributed by the different units of the block copolymer.The ethylene oxide unit traps polysulfide,which bonds strongly with the intermediate lithium polysulfide,and enhances the transport of lithium ions to reach high capacity.Meanwhile,the styrene unit maintains cathode integrity by improving the mechanical properties and elasticity of the constructed block copolymer to accommodate the large volume changes.By enabling multiple functions via different units in the polymer chain,high sulfur utilization is achieved,polysulfide diffusion is confined,and the shuttle effect is suppressed during the cycle life of Li-S batteries,as revealed by operando ultraviolet-visible spectroscopy and S Kedge X-ray absorption spectroscopy.

Minimal invasive microscopic tooth preparation in esthetic restoration: a specialist consensus

By removing a part of the structure,the tooth preparation provides restorative space,bonding surface,and finish line for various restorations on abutment.Preparation technique plays critical role in achieving the optimal result of tooth preparation.With successful application of microscope in endodontics for>30 years,there is a full expectation of microscopic dentistry.However,as relatively little progress has been made in the application of microscopic dentistry in prosthodontics,the following assumptions have been proposed:Is it suitable to choose the tooth preparation technique under the naked eye in the microscopic vision?Is there a more accurate preparation technology intended for the microscope?To obtain long-term stable therapeutic effects,is it much easier to achieve maximum tooth preservation and retinal protection and maintain periodontal tissue and oral function health under microscopic vision?Whether the microscopic prosthodontics is a gimmick or a breakthrough in obtaining an ideal tooth preparation should be resolved in microscopic tooth preparation.This article attempts to illustrate the concept,core elements,and indications of microscopic minimally invasive tooth preparation,physiological basis of dental pulp,periodontium and functions involved in tool preparation,position ergonomics and visual basis for dentists,comparison of tooth preparation by naked eyes and a microscope,and comparison of different designs of microscopic minimally invasive tooth preparation techniques.Furthermore,a clinical protocol for microscopic minimally invasive tooth preparation based on target restorative space guide plate has been put forward and new insights on the quantity and shape of microscopic minimally invasive tooth preparation has been provided.

Understanding fluorine-free electrolytes via small-angle X-ray scattering

Fluorine-free electrolytes have attracted great attention because of its low-cost and environmental friendliness. However, so far, little is known about the solution structures of these electrolytes. Here,we compare the solvation phenomenon of sodium tetraphenylborate(NaBPh_(4)) salt dissolved in organic solvents of propylene carbonate(PC), 1,2-dimethoxyethane(DME), acetonitrile(ACN) and tetrahydrofuran(THF). Small-angle X-ray scattering(SAXS) reveals a unique two-peak structural feature in this saltconcentrated PC electrolyte, while solutions using other solvents only have one scattering peak.Molecular dynamics(MD) simulations further reveal that there are anion-based clusters in addition to the short-range charge ordering in the concentrated NaBPh4/PC electrolyte. Raman spectroscopy confirms the existence of considerable contact ion pairs(CIPs). This work emphasizes the importance of global and local structural analysis, which will provide valuable clues for understanding the structureperformance relationship of electrolytes.