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The primary objective of the present investigation is to elucidate the operative micromechanisms influencing the strain rate sensitivity and activation volume in (FeCrNi)99Si1 and FeMnNi medium-entropy alloys. Room-temperature nanoindentation experiments at different loading rates were performed to study the evolution of the strain rate sensitivity and activation volume in (FeCrNi)99Si1 and FeMnNi medium-entropy alloys. The (FeCrNi)99Si1 samples were subjected to plane strain deformation by rolling at 77 and 300 K to study the effect of temperature on the strain rate sensitivity, while the FeMnNi and (FeCrNi)99Si1 samples were subjected to simple shear deformation by high-pressure torsion at 300 K to examine the effect of strains. Contrary to the well-documented trend observed in fcc metals and alloys, where the strain rate sensitivity typically increases with decreasing grain size, the present study reveals a distinct behavior for the current alloys. Similarly, these alloys are characterized by extremely low activation volumes of a few tens of b3 compared to 100–1000 b3 for conventional fcc metals and alloys in the microcrystalline grain size regime. Unlike conventional fcc metals and alloys, there is an insignificant change in the activation volume of the current high-/medium-entropy alloy (H/MEA) with decreasing grain size from the microcrystalline to nanocrystalline regime. The unique evolution of strain rate sensitivity and activation volume in H/MEAs is explained in terms of the evolution of distinct dislocation structures as well as synergistic operation of additional mechanisms such as twinning, phase transformation from fcc to hcp phases, cluster strengthening, and short-range ordering due to the aperiodic energy landscape existing in MEAs. [ABSTRACT FROM AUTHOR]

FCC-HCP phase transition plays a pivotal role in many intelligent materials, which also occurs in Pb under high pressures. However, its impacts on the spallation of polycrystalline, as well as the effects related to grain size, are still unclear. In this work, spallation behaviors of Pb polycrystals with different grain sizes under various shock loadings are investigated using the quasi-coarse-grained molecular dynamics (QCGD) method based on our recently developed response embedding atom model potential. The QCGD method is rigorously validated for applications in the metals exhibiting solid–solid phase transitions. Due to the restriction of the critical size for the phase transition nucleus, the coarsening level of the QCGD method cannot exceed two times the lattice parameter. Nevertheless, such a method enables us to explore the whole rule of the grain-size-dependence incipient spall strength. Our results suggest that the incipient spall strength exhibits a transition from the Hall–Petch to the inverse Hall–Petch relationship at about 13 nm and the spallation strength converging to that of a single crystal for grain sizes larger than 60 nm. As the grain size decreases, void nucleation becomes more prevalent than void growth, making the material better equipped to prevent the progression of damage into fractures. When the grain size is sufficiently large, voids nucleate and grow in the grain interior, making the spallation behave like in a single crystal. Interestingly, the phase transition from HCP to FCC phase enhances dislocation entanglement, leading to heterogeneous nucleation of voids in the grain interior. [ABSTRACT FROM AUTHOR]

The functional properties of piezoelectric ceramic materials, such as barium titanate, are highly dependent on grain size. Lead-free polycrystalline Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) samples were prepared with a combination of the hydrothermal method and spark plasma sintering to achieve grain sizes from 100 nm to 10 μm by varying the maximum sintering temperature. In this range, a transition from a nearly linear dielectric to a ferroelectric response can be seen in macroscopic electromechanical measurements, demonstrating the importance of grain size on functional properties in BCZT. Furthermore, in situ electric field-dependent synchrotron x-ray diffraction measurements were performed to quantify the intrinsic and extrinsic strain contributions and their variations with grain size. At lower grain sizes, the data revealed a significant loss of extrinsic contributions in the piezoelectric behavior, limiting the response to intrinsic contribution associated with lattice strain. For BCZT, a critical grain size between approximately 0.08 and 0.18 μm is proposed, below which no piezoelectric response was observed. [ABSTRACT FROM AUTHOR]

Size effect is a fundamental phenomenon in ferroelectric materials and grain size dependence of the dielectric and piezoelectric properties of BaTiO3 (BTO) ceramics has been observed. However, the dependence of flexoelectric response on grain size has not been reported, thus far. In this work, BTO ceramics with grain sizes ranging from 0.59 to 8.90 μm were prepared by a two-step sintering method. We found that with increasing grain size, the flexoelectric coefficient of BTO ceramics increases from less than 20 μC/m (grain size 0.59–0.69 μm) to more than 300 μC/m (grain size 8.90 μm), but the grain size dependence of the flexoelectric response is different from that of the dielectric and piezoelectric properties. Observation by piezoresponse force microscopy reveals that the surface regions of BTO ceramics are spontaneously polarized. Strong inhomogeneous strain is measured by grazing incidence x-ray diffraction and the resultant flexoelectric effect is enough to polarize the surface regions. Fitting of the flexoelectric data indicates that the grain size effect of the flexoelectric response can be well explained by the polarized surface layer mechanism. [ABSTRACT FROM AUTHOR]

We conducted a comprehensive investigation on the influence of TiN thickness and stress on the ferroelectric properties of Hf 0.5 Zr 0.5 O 2 thin films. TiN top electrode layers with varying thicknesses of 2, 5, 10, 30, 50, 75, and 100 nm were deposited and analyzed. It was observed that the in-plane tensile stress in TiN films increased with the thickness of the TiN top electrode. This is expected to elevate the tensile stress in the Hf 0.5 Zr 0.5 O 2 film, consequently leading to an enhancement in ferroelectric polarization. However, the effect of stress on the ferroelectric behavior of Hf 0.5 Zr 0.5 O 2 films exhibited distinct stages: improvement, saturation, and degradation. Our study presents novel findings revealing a saturation and degradation phenomenon of in-plane tensile stress on the ferroelectric properties of polycrystalline Hf 0.5 Zr 0.5 O 2 films, thereby partially resolving the discrepancies between experimental observations and theoretical predictions. The observed phase transformation induced by tensile stress in Hf 0.5 Zr 0.5 O 2 films played a crucial role in these effects. Furthermore, we found that the impact of the TiN top electrode thickness on other factors influencing ferroelectricity, such as grain size and oxygen vacancies, was negligible. These comprehensive results offer valuable insights into the influence of stress and TiN top electrode thickness on the ferroelectric behavior of Hf 0.5 Zr 0.5 O 2 films. [ABSTRACT FROM AUTHOR]

Grain rotation caused by the movement of dislocations is a determinant factor for the mechanical behavior of metals. In general, the grain rotation may be mediated by grain boundary dislocations (GB-dis) and intragranular dislocations (In-dis), which are closely associated with grain size. Few works have investigated how grain size depends on grain rotation, and the competitive mechanism between GB-dis and In-dis remains unclear. The present work investigates the structural evolution and deformation of coarse-grained tungsten under high pressure. The results show that under high pressure, the nano-sized grains preferentially rotate with dislocation climbing in GBs. Under high pressure, In-dis migrate faster across coarse grains and are absorbed by GBs on the other side, resulting in grain rotation. Elevated temperature also facilitates the migration of In-dis to arrive GBs where they can be absorbed by GBs, thus promoting grain rotation. The theoretical results show that grain rotation occurs easily under high pressure and high temperature. With increasing grain size, the stress-induced rotation mechanism goes from being dominated by GB-dis to being dominated by In-dis migration. The competitive relationship between GB-dis and In-dis during grain rotation is elaborated, providing a new strategy for designing materials under high pressure. [ABSTRACT FROM AUTHOR]

The investigation and tunning of positive exchange bias (PEB) and negative exchange bias (NEB) are reported at room temperature (RT) and low temperature (20 K), respectively, in a series of top-pinned Ni81Fe19(tFM = 5, 8, 11, 14, 17, and 20 nm)/Ir7Mn93(10 nm) polycrystalline heterostructure thin films grown in the presence of a 1 kOe in situ magnetic field by systematically controlling the microstructural parameters such as thickness, roughness, and crystallite/grain size. On decreasing the thickness (roughness) of NiFe from 20 nm (0.49 nm) to 5 nm (0.28 nm), an enhancement in PEB and NEB is observed from +12 to +22 Oe and −300 to −556 Oe at RT and 20 K, respectively. It is observed that both exchange bias and coercivity substantially depend on the atomic scale roughness of the interface width (NiFe/IrMn). The representative plane-view of transmission electron microscopy (TEM) measurements revealed the enhanced antiferromagnet (AF) grain size on decreasing the thickness of ferromagnetic, whereas cross-sectional TEM studies exhibited the sharp interfaces in the bilayer samples after magnetic annealing. A unique correlation between the training mechanism and the degree of asymmetry is established. Further, the training measurement data are fitted with various theoretical models that support the fact that not only interfacial but also bulk AF spins play a vital role in the exchange bias. Thus, the present study reveals the microstructural insights by varying the thickness of NiFe to address the unresolved issues of the EB by directly correlating it with interface roughness and the crystallite/grain size of AF in it, probed using the magnetoresistance technique. [ABSTRACT FROM AUTHOR]

The thermal conductivity (k) of polycrystalline SiC thin films is relevant for thermal management in emerging SiC applications like microelectromechanical and optoelectronic devices. In such films, k can be substantially reduced by microstructure features including grain boundaries, thin film surfaces, and porosity, although these microstructural effects can also be manipulated through thermal annealing. Here, we investigate these effects by using microfabricated suspended devices to measure the thermal conductivities of nine low-pressure chemical vapor deposition SiC films of varying thicknesses (from 120 to 300 nm) and annealing conditions (as-grown and annealed at 950 and 1100 °C for 2 h, and in one case 17 h). Fourier-transform infrared spectroscopy, x-ray diffraction spectra, and density measurements are also used to characterize the effects of annealing on the microstructure of selected samples. Compared to as-deposited films, annealing at 1100 °C typically increases the estimated grain size from 5.5 to 6.6 nm while decreasing the porosity from around 6.5% to practically fully dense. This corresponds to a 34% increase in the measured thin film thermal conductivity near room temperature from 5.8 to 7.8 W/m K. These thermal conductivity measurements show good agreement of better than 3% with fits using a simple theoretical model based on the kinetic theory combined with a Maxwell–Garnett porosity correction. Grain boundary scattering plays the dominant role in reducing the thermal conductivity of these films compared to bulk single-crystal values, while both grain size increase and porosity decrease play important roles in the partial k recovery of the films upon annealing. This work demonstrates the effects of modifying the microstructure and, thus, the thermal conductivity of SiC thin films by thermal annealing. [ABSTRACT FROM AUTHOR]

In recent years, the implementation of thin-film Ta has led to improved coherence times in superconducting circuits. Efforts to further optimize this materials set have become a focus of the subfield of materials for superconducting quantum computing. It has been previously hypothesized that grain size could be correlated with device performance. In this work, we perform a comparative grain size experiment with α -Ta on c axis sapphire. Our evaluation methods include both room-temperature chemical and structural characterization and cryogenic microwave measurements, and we report no statistical difference in device performance between smaller- and larger-grain-size devices with grain sizes of 924 and 1700 nm 2 , respectively. These findings suggest that grain size is not correlated with loss in the parameter regime of interest for Ta grown on c axis sapphire, narrowing the parameter space for optimization of this materials set. [ABSTRACT FROM AUTHOR]

The behavior of energetic materials is significantly influenced by the spatial distributions of microstructure heterogeneities and voids. We pursue the concept of Functionally Graded Energetic Materials whose microstructure features (e.g., grain size, grain volume fraction, void size, and void volume fraction) change spatially such that they may allow the behavior of the materials to be tailored. We explore using gradients in the density of voids to alter the detonation behavior of a polymer-bonded explosive (PBX) echoing PBX9501 with HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) grains and Estane binder. Five cases, two graded void distributions from 1% to 10% and 10% to 1% by volume along the length of the sample, and three uniform distributions matching the lowest (1%), average (5.5%), and highest (10%) void densities are considered. An Arrhenius reaction burn model is used to account for the chemical kinetics of HMX. Different detonation behaviors are obtained from the same graded sample when impact loading is from 1% void end and from the 10% void end as well as from the uniform cases. The SDT (shock to detonation transition) behaviors are analyzed in terms of the run distance, the time duration and shock velocity changes over the SDT process. The computational results are presented in the context of available experimental data for PBX9501 with which agreement is obtained through a parametric study. Overall, it is shown that gradients in microstructures of PBX can lead to SDT behaviors different or not obtainable from microstructures without gradients, thereby offering a mechanism for designing and tailoring new materials. [ABSTRACT FROM AUTHOR]

Coarse-grained (CG) simulation models of condensed-phase systems can be derived with well-established methods that perform coarse-graining in space and provide an effective Hamiltonian with which some of the structural and thermodynamic properties of the underlying fine-grained (FG) reference system can be represented. Coarse-graining in time potentially provides CG models that furthermore represent dynamic properties. However, systematic efforts in this direction have so far been limited, especially for moderately coarse-grained, chemistry-specific systems with complicated conservative interactions. With the aim of representing structural, thermodynamic, and dynamic properties in CG simulations of multi-component molecular systems, we investigated a recently introduced method in which the force on a CG particle originates from conservative interactions with surrounding particles and non-Markovian dissipative interactions, the latter introduced by means of a colored-noise thermostat. We examined two different methods to derive isotropic memory kernels required for integrating the corresponding generalized Langevin equation (GLE) of motion, based on the orthogonal dynamics of the FG forces and on an iterative optimization scheme. As a proof of concept, we coarse-grain single-component molecular liquids (cyclohexane, tetrachloromethane) and ideal and non-ideal binary mixtures of cyclohexane/tetrachloromethane and ethanol/tetrachloromethane, respectively. We find that for all systems, the FG single particle velocity auto-correlation functions and, consequently, both the short time and long time diffusion coefficients can be quantitatively reproduced with the CG-GLE models. We furthermore demonstrate that the present GLE-approach leads to an improved description of the rate with which the spatial correlations decay, which is artificially accelerated in the absence of dissipation. [ABSTRACT FROM AUTHOR]

The goal of this article was to analyze the microstructural, texture development, deformation mode, and mechanical properties of a Mg–8.7Gd–4.18Y–0.42Zr (wt%) magnesium alloy that underwent conventional extrusion in conjunction with equal channel angular pressing (EX-ECAP) deformation. The findings indicate that as-extruded alloy reveals a significant basal texture, while the ECAPed GW94K alloy demonstrates basal poles that are inclined ~ 45° from the extrusion direction. After 4p-ECAP process at 370 °C via the Bc path, the microstructure of the alloy exhibits a high level of uniformity, with a fine grain area fraction of 92.7% and an average grain size of 3 μm. The GW94K alloy experiences a significant increase in elongation when the ECAP pass is increased, although the ultimate tensile strength (UTS) decreases remarkably. In particular, the sample subjected to ECAP demonstrates a room-temperature tensile elongation of 36.8% in the extrusion direction. This phenomenon can be ascribed primarily to the evolution of the texture during repeated ECAP processes, leading to the activation of multiple deformation modes in ECAP deformation process of the GW94K alloy. Furthermore, the results suggest that the presence of multiple slip systems, characterized by their high Schmid factor and IGMA analyses, significantly influences the uniform elongation. [ABSTRACT FROM AUTHOR]

The interaction between the topography of the slope zone on the edge of the basin and the distribution of sediments is crucial for accurately predicting sediment distribution, but few studies emphasize the impact of stratigraphic overlap on the spatial evolution of sedimentary facies. The tectonic movement and sedimentary environment of Hala'alat Mountain in the northwest margin of the Junggar Basin are complex, and the sedimentary model of the whole Cretaceous system is still unclear. This article uses lithology, logging, and seismic data to explain the evolution process and sedimentary model of the Cretaceous system. The significant overlap of Cretaceous strata in the research area has a significant impact on the distribution of sedimentary facies zones and the development of sedimentary systems. Furthermore, this article explores the genesis mechanism of the Cretaceous stratigraphic overlap phenomenon, clearly defines the boundary range of stratigraphic overlap, and deeply analyzes how sedimentary facies zones are distributed and their subsequent evolution trends after the formation of overlap. The results demonstrate that there are apparent stratigraphic overlap phenomena in the second member (K1q2) and the third member (K1q3) of the Cretaceous Qingshuihe Formation in this area. The lithology at the bottom of the formation is grey sand conglomerate with finer grain size in the upper part, and the sedimentary facies are transitioned from fan delta facies to shore shallow lake beach bar facies. In member 1 (K1h1), member 2 (K1h2) and member 3 (K1h3) of the Hutubi Formation, due to the gradual slope and relatively stable sedimentary environment, the distance of stratigraphic overlap becomes shorter, the stratigraphic overlap phenomenon is no longer apparent and the sedimentary facies zone does not change. The study not only reveals the intrinsic relationship between stratigraphic overlap and the distribution of sedimentary facies zones, but also deepens the understanding of the dynamic evolution laws of sedimentary systems. The study on the overlap sedimentary mechanism of the Hala'alat Mountain in the northwest margin of Junggar Basin has reference significance. [ABSTRACT FROM AUTHOR]

The roles of plant-specific transcription factor family YABBY may vary among different members. OsYABBY6 is a rice YABBY gene, whose function is not well elucidated so far. In this paper, we show that OsYABBY6 is a nucleus-localized protein with transcriptional activation activity. OsYABBY6 is predominantly expressed in the palea and lemma, as well as in the sheath, culm and node. OsYABBY6 RNA interference (RNAi) plants exhibited altered plant height and larger grain size. Under cold treatment, OsYABBY6 overexpression (OE) plants had up-regulated expression of cold responsive genes, and accumulated less reactive oxygen species but more proline compared to wild type, resulting in improved cold tolerance. On the other hand, RNAi plants showed enhanced drought tolerance compared to the wild type by slower water loss, less reactive oxygen species but more proline and soluble sugar accumulation. In addition, endogenous abscisic acid (ABA) level was reduced in OsYABBY6 RNAi plants, and RNAi and OE plants were more and less sensitive to ABA treatment, respectively. Accordingly, we deduce that OsYABBY6 positively regulates cold response but negatively regulates drought response through different pathways. Our study reveals the crucial roles of OsYABBY6 in plant architecture and grain development, as well as in abiotic stress response, providing new insights into the functions of YABBYs in rice. [ABSTRACT FROM AUTHOR]

In this study, we investigated the charged domain wall structure of lead-free piezoceramics (Na0.55K0.45)NbO3 using multiple microscopy techniques. It was found that the oxygen partial pressure during sintering affected the volatilization of A2O (A = Na, K), whereby the resulting vacancies were found to be related to grain sizes. In the polycrystals sintered under the air atmosphere condition, almost all grains show rapid grain growth and complex domain structures containing striped and indefinite shaped domains as revealed by confocal laser microscope and piezoelectric force microscope images. Transmission electron microscopy showed that a part of these domain structures has charged domain walls due to bending the 180° domain walls. The A-site vacancies, such as Na and K, lead to forming large grains and charged domain wall structures. [ABSTRACT FROM AUTHOR]

This study investigates the impact of two distinct methodologies on the structural, morphological, and gas sensing properties of TiO2/SiC/CoFe2O4 (TSC) nanocomposites determined using x-ray diffraction (XRD), scanning electron microscopy (SEM), LCR meter, and gas sensing unit respectively. The TiO2/SiC/CoFe2O4 nanocomposites were synthesized using chemical co-precipitation method (C-TSC) and the solid state method (G-TSC). The Scherrer formula was used to calculate the average grain size of C-TSC and G-TSC, which was estimated to be 8 ± 2 nm and 10 ± 2 nm, respectively. The formation of TSC nanocomposites was confirmed by XRD, SEM, and EDX analysis. The response (%) toward ethanol and NH3 gas was tested as a function of flow rate (ppm) and temperature from room temperature (28 °C) to 300 °C. The response (%) was observed to be increasing with increasing temperature and three intermediate temperatures were found. The response and recovery time were also measured with varying gas concentrations. The long-term stability of devices was tested up to 30 days and less variation in result was found, which confirms stability of sensor. The material synthesized using chemical co-precipitation method (C-TSC) shows better properties than G-TSC. [ABSTRACT FROM AUTHOR]

Grain size refinement is one of the most effective and feasible approaches to tailor the mechanical properties of metals and alloys. This classic strengthening mechanism is recently highlighted in Ni-Co-Cr-Fe-based high-entropy alloys due to its extremely large Hall–Petch coefficient of 1100 MPa·μm1/2. However, the grain growth kinetics of Ni-Co-Cr-Fe, which serve as the guideline for controlling the grain size of related high-entropy alloys (HEAs), are still unclear. Here, we investigated the grain growth behaviors of Ni2CoCrFe, NiCo2CrFe, and NiCoCrFe2. Our results show that the grain growth kinetics of Ni-Co-Cr-Fe are highly dependent on the concentration of its principal elements. The grain growth activation energies are 315, 622, and 570 KJ/mol for Ni2CoCrFe, NiCo2CrFe, and NiCoCrFe2, respectively. This big difference is mainly attributed to the degree of grain boundary segregation caused by the interactions between different atomic pairs. These findings are helpful for designing HEAs with controllable microstructures. [ABSTRACT FROM AUTHOR]

Microstructure evolution on the surface of Fe-20Mn-6Al-0.6C-0.15Si austenitic low-density steel was studied by comparing with the microstructure at the core. In the present study, the austenite grain growth was in situ observed using laser scanning confocal microscope (LSCM). The microstructure of specimens on surface and at core was analyzed after LSCM experiments. The distribution of Mn and Al along axial direction was analyzed. The results show that the volatilization of Mn on the specimen surface during isothermal holding at high temperatures varying from 900 to 1200 °C results in a low stability of the austenite on the specimen surface, leading to the transformation of less stable austenite to ferrite during subsequent cooling process. The ferrite fraction on the specimen surface increases with isothermal temperature, indicating more Mn volatilization at higher temperature. In addition, because Mn volatilizes during isothermal holding at high temperatures, the austenite grain growth on the surface is different from that at the core. [ABSTRACT FROM AUTHOR]

This paper proposes an innovative multi-scale method for determining gas pressure parameters of superplastic forming, which is based on the quantitative relationship between the grain growth mechanism and fracture mechanism of Tie6Ale4V alloy. The high-temperature tensile tests were conducted on the material at temperatures ranging from 700, 800, 840, 890, 920, and 950 °C, strain rates were selected as 10-2~10-4/s. The grain size measurements were observed using electron back-scatter diffraction (EBSD). Particularly, the relation between grain size changes and fracture behaviour is specifically discovered using a physically-based dynamic material model (DMM), and the grain size thresholds for each forming limit are proposed. The physical fracture mechanism is named the "Grain growth based fracture (GGBF)" mechanism. Furthermore, an innovative method based on the GGBF mechanism is proposed to design the superplastic forming loading, and practical four-layer hollow structures experiments are applied to validate the fracture mechanism in superplastic forming. In total, A superplastic forming GGBF mechanism has been verified, and it is expected to be helpful for shape and property control in the forming process of complex structures. [ABSTRACT FROM AUTHOR]

The elaboration of suitable NdFeB‐based permanent magnets is essential for high‐performance electrical machines in a number of applications. In this respect, the understanding of the relationship between heat transfer phenomena and the final solidified microstructure is the key to the control of the grain size and the improvement of the magnetic properties. The problem is even more acute with the emergence of new manufacturing processes, such as the laser powder bed fusion, where the cooling rates are much higher than those encountered in the standard strip casting process and where the microstructure can be considered as fixed from the fabrication step. The objective of the present work is to identify correlations between interstructural spacings in the solidified alloys and cooling conditions. This study is based on a methodology coupling experimental and numerical simulation approaches featuring three solidification processes: strip casting, arc melting, and laser fusion. The obtained results cover more than four orders of magnitude in terms of cooling rates R and allow to propose a reliable empirical relationship between the interstructural spacing λ and R of the form λ [μm] = 83 R [K s−1]−0.36. This relation can thus be used to estimate cooling rates from metallographic observations. [ABSTRACT FROM AUTHOR]

Wide‐bandgap perovskite solar cells (PSCs) play crucial roles in determining the overall efficiencies of all‐perovskite tandem solar cells (TSCs). Tailoring the grain growth process is a key route to improve the film quality and device performance. Herein, a facile passivator‐assisted close space annealing (PA‐CSA) strategy to simultaneously enlarge the crystal size and passivate the defects is demonstrated. Filter paper is used as the solvent permeable membrane to slow down the fast crystallization and enlarge the grain size. At the same time, a precisely selected volatile material (fluorizated‐phenethylammonium chloride) embedded in the filter paper is employed as the passivator to eliminate defects in wide‐Eg perovskite film during annealing. The PA‐CSA‐processed wide‐Eg PSCs obtain the champion efficiencies of 21.28% (1.68 eV) and 20.24% (1.73 eV), enabling high‐performance all‐perovskite TSCs with efficiencies reaching 27% in both four‐terminal and monolithic two‐terminal tandem configurations, respectively. This PA‐CSA strategy provides an in situ passivating process for high‐performance PSCs and TSCs upon further industrial applications. [ABSTRACT FROM AUTHOR]

Powders that absorb sound by longitudinal vibration have either a gentle or sharp sound absorption curve at the first absorption peak frequency. Experiments were performed to investigate the conditions under which longitudinal vibration occurs in powders of various grain sizes and bulk densities. The sound absorption characteristics of the powders were then classified according to their specifications, and the sound absorption coefficients predicted by derived empirical equations were compared with the measured sound absorption coefficients. A threshold value for the areal density per grain layer was identified where lightweight powders at 0.0006 g/cm2 or less demonstrated useful sound absorption characteristics via longitudinal vibration. Powders with smooth (i.e., useful) and sharp (i.e., not useful) sound absorption curves could be further identified by the half-width value at 0.0974 < log f2 − log f1 < 0.119 decade. The bulk density can also be used to identify powders with useful sound absorption characteristics at 0.0868 < ρ < 0.124 g/cm3. A regression analysis was performed to obtain empirical equations expressing the relationship between the areal density per grain layer and first sound absorption peak frequency normalized by the layer thickness. [ABSTRACT FROM AUTHOR]

Bipolar plates are one of the most important components of proton exchange membrane fuel cells. With the miniaturization of bipolar plate flow channel sizes and the increasing demand for precision, springback has become a key focus of research in the bipolar plate forming process. In this paper, the hydroforming process for 316L stainless steel bipolar plates was studied, and an FEM model was built to examine the stress and strain at various locations on the longitudinal section of the plate. Modeling accuracy was validated by the comparison of experimental profile and thickness distribution. The effects of forming pressure and grain size on springback behavior are discussed. The results show that with increasing forming pressure, the springback value decreases initially, followed by an increase, but then again decreases. When the forming pressure is 80 MPa–100 MPa, the deformation of the lower element of the upper rounded corner is not uniform with more elastic regions, and the springback is positively correlated with forming pressure. The springback distribution pattern on the cross-section of the bipolar plate changes from a normal distribution to a distribution of "M" shape with increased pressure. The larger the grain size, the lower the yield strength elastic proportion, resulting in a decrease in springback of the sheet. The maximum amount of springback of the bipolar plate is 3.1 μm when the grain size is 60.7 μm. The research results provide a reference for improving the forming quality of metal bipolar plates with different flow channel shapes. [ABSTRACT FROM AUTHOR]

In order to improve the microwave-absorption performance of barium ferrite and broaden its microwave-absorption band, BaFe12O19, Ba0.95Ca0.05Fe12O19, and Ba0.95Ca0.05Fe12−xCoxO19 (x = 0.1, 0.2, 0.3 and 0.4, respectively) hexaferrites were synthesized by the solid-state reaction method, and the influence of Co ion substitution on the phase composition, microstructure, magnetic properties, and microwave-absorption ability of the ferrites in this system was studied. Introducing minor Co ions (x < 0.2) facilitated sintering and grain growth. At x ≥ 0.2, XRD revealed the emergence of the Co2X phase alongside the BaM phase. Increasing Co ion concentration and the secondary X-phase led to slight reductions in saturation magnetization (69 to 63.5 emu/g) and substantial decline in coercivity (2107.02 to 111.21 Oe), attributed to grain size growth and Co2X's soft magnetic nature. Notably, Co2X incorporation significantly enhanced the microwave absorption and provided a tunable absorption band from the Ku to the C band. For a sample with a thickness of 2.0 mm and a doping level of x = 0.2, a minimum reflection loss of −59.5 dB was achieved at 8.92 GHz, with an effective absorption bandwidth of 3.31 GHz (7.07–10.38 GHz). The simple preparation method and good performance make Ba0.95Ca0.05Fe12−xCoxO19 (x = 0.1, 0.2, 0.3 and 0.4, respectively) hexaferrites promising microwave-absorbing materials. [ABSTRACT FROM AUTHOR]

The influence of as-cast grain size on recrystallization and the related mechanical properties of Al–Zn–Mg–Cu-based alloys was investigated. Grain sizes ranging from 163 to 26 μm were achieved by adding Ti, Cr and Mn, and ZnO nano-particles, which acted as heterogeneous nucleation sites. A decrease in the as-cast grain size led to a corresponding reduction in the recrystallized grain size from 54 to 13 μm. Notably, as-cast grain sizes below 100 μm provided additional nucleation sites at grain boundaries, allowing for a reasonable prediction of recrystallized grain size. Finer grains also contributed to enhanced mechanical properties, with yield strength increasing as recrystallized grain size decreased without significant loss of elongation. Additional strengthening was observed due to η-precipitates at grain boundaries, further improving the properties of fine-grained sheets. [ABSTRACT FROM AUTHOR]

In this study, the effects of the length-to-width ratio on the magnetic and microstructural properties of die-upset Nd–Fe–B magnets were examined. A die-upset magnet with a uniform shape and no significant cracking was successfully developed. During the die-upset process, the applied pressure was not uniform across the magnet and varied depending on its shape and position. In the case of the magnet with a 4:1 ratio, which had the largest length-to-width ratio, there was a higher concentration of stress at the edges compared to the center, resulting in easier grain deformation and growth at the edges, which led to the lowest remanence and (BH)max. As the length-to-width ratio approached 1:1, the grain size increased slightly, reducing the coercivity; however, the magnets maintained a uniform grain-size distribution. The change from a rectangular to a square pressing surface resulted in a more uniform stress distribution, particularly at the center and corners, which improved the consistency of the magnetic properties across different regions of the magnet. Consequently, an 11.9% enhancement in (BH)max, reaching 285.6 kJ/m3, was achieved in the 1:1 ratio die-upset magnet, which is attributed to the uniform grain size and improved grain alignment. [ABSTRACT FROM AUTHOR]

Optical characteristics and microstructure of multilayered zirconia with different yttria contents in each layer can be influenced differently with a layer after speed sintering. The layer-wise translucency and opalescence of dental zirconia (E.max, E.max ZirCAD prime; Cercon, Cercon ht ML) after conventional (control) and speed sintering were analyzed using a spectrophotometer (n = 5). Specimens were subjected to microstructural analyses (n = 2) using field-emission scanning electron microscopy (FE-SEM) and phase analyses (n = 1) using high-resolution X-ray diffraction (HRXRD) and Rietveld refinement. The translucency parameter (TP) and opalescence parameter (OP) were analyzed using a 3-way ANOVA, followed by Scheffé's post hoc test (α = 0.05). The average grain size was analyzed using the Welch's t-test and Kruskal–Wallis test, followed by the Bonferroni–Dunn post hoc test (α = 0.05). Changes to the TP and OP after speed sintering were only observed in the dentin layers. Although the TP of E.max increased (p < 0.05), the difference was below the 50:50% perceptibility threshold (ΔE00 = 0.8). The OP of E.max decreased slightly, whereas that of Cercon increased slightly (p < 0.05). The microstructure and phase fraction of both zirconia barely changed. Therefore, speed sintering is considered to have a negligible clinical impact on the optical characteristics and microstructure. [ABSTRACT FROM AUTHOR]

Reliable paleoflood proxies can help reconstruct past flood variation patterns. Here, we investigated the grain-size data of a 63 cm core retrieved from Lake Chaonaqiu, western Chinese Loess Plateau, in order to build a long time-series of flood occurrence from sedimentology that extends the period of instrumental data. Our results indicate that three parameters (mean, standard deviation and grain-size ratio of 16–63/2–16 μm) are sensitive to hydrodynamic changes in Lake Chaonaqiu, which are further linked to high-energy inflow associated with high-intensity rainfall or flood events. These three parameters' variations were well correlated with the precipitation records reconstructed from tree-rings and historical documents in neighboring regions and overlapped with 109 historical flood events from historical documents in counties around the lake for the past 300 years. Therefore, we propose that the grain size in the sediments of Lake Chaonaqiu is a reliable paleoflood proxy. The sensitivity of flood signals to grain size may be related to the precipitation and vegetation cover in the catchment of the lake, which are further linked to the strength of the East Asian summer monsoon. [ABSTRACT FROM AUTHOR]

Contemporary Li‐ion batteries are facing substantial challenges like safety and limited energy density. The development of all‐solid‐state battery cells mitigates safety hazards and allows the use of Li‐metal anodes increasing energy density. Garnet‐type solid electrolytes can be vital to achieving an all‐solid‐state cell and an understanding of the influence of its microstructure on the electrochemical performance is crucial for material and cell design. In this work the influence of grain size on the Li‐ion conductivity of Li7‐3xLa3Zr2AlxO12 (x=0.22) is presented. The synthesis and processing procedure allows changing the ceramic grain size, while maintaining the same synthesis parameters, eliminating influences of the synthesis on grain boundary composition. Field assisted sintering technology is a powerful method to obtain dense, fine‐grained ceramics with an optimal grain size of 2–3 μm, where the conductivity is double that of the counterpart (0.7 μm). A total Li‐ion conductivity of 0.43 mS cm−1 and an activation energy of 0.36 eV were achieved. The oxide‐based all‐solid‐state battery cell combining the garnet‐type electrolyte, a Li‐metal anode and a thin‐film LiCoO2 cathode was assembled and cycled at room temperature for 90 hours. This represents a proof of concept, for the application of oxide‐based electrolytes at ambient temperatures. [ABSTRACT FROM AUTHOR]

To reveal the relationship between microstructures and mechanical properties in friction stir welding under water (FSWUW), a numerical model is proposed with full experimental validations. Monte Carlo model was established to simulate the recrystallization, and precipitate evolution model was developed to study the mechanical property changes. It was found that the main strengthening phase is changed from precipitates to Cu–Mg co-cluster in FSWUW due to the higher cooling rate. Results indicated that the maximum temperature is decreased by 20.2–44.7%, and the maximum cooling rate is increased by 92.4–344.5% in FSWUW compared with friction stir welding (FSW). The change of the temperature variations leads to the decrease in the average grain size by 6.6–44.8% in FSWUW. Due to the high cooling rate in FSWUW, the precipitate growth is limited, and Cu–Mg co-cluster consists of the main phase in the final microstructure, which leads to the change of the main contribution item to the yield strength in FSWUW. In FSWUW, the contribution from the Cu–Mg co-clusters is the main contribution to the yield strength and ranges 61.3–73.4% of the final yield strength. The average grain size and the maximum cooling rate decreases with the increase in the translational speed and the decrease in the rotating speed in the heat-affected zone of FSWUW. [ABSTRACT FROM AUTHOR]

This work investigates the effect of the microstructure of the as-quenched precursors prepared at various cooling rates on the soft magnetic characteristics and its sensitivity to the annealing heat rate (HR) of the Fe83.5Si3B10P2Cu1.5 nanocrystalline alloy. The results of Mössbauer spectra indicate that the cooling rate during the melt spinning process significantly impact the microstructure of as-quenched alloy samples. The decrease in the cooling rate facilitates the formation of an amorphous/nanocrystalline precursor containing more "α-Fe-like" structure and Cu-clusters. Variations of grain size and Hc with heating rate indicate that Fe83.5Si3B10P2Cu1.5 alloy samples prepared at a low cooling rate are less sensitive to the heating rate during crystallization annealing. The Fe83.5Si3B10P2Cu1.5 nanocrystalline alloy prepared at low cooling rate can achieve excellent soft magnetic properties with low HR annealing. [ABSTRACT FROM AUTHOR]

The abounding variations in wild rice provided potential reservoirs of beneficial genes for rice breeding. Maintaining stable and high yields under environmental stresses is a long-standing goal of rice breeding but is challenging due to internal trade-off mechanisms. Here, we report wild rice GL12W improves grain length and salt tolerance in both indica and japonica genetic backgrounds. GL12W alters cell length by regulating grain size related genes including GS2, and positively regulates the salt tolerance related genes, such as NAC5, NCED3, under salt stresses. We find that a G/T variation in GL12 promoter determined its binding to coactivator GIF1 and transcription factor WRKY53. GIF1 promotes GL12W expression in young panicle and WRKY53 represses GL12W expression under salt stresses. The G/T variation also contributes to the divergence of indica and japonica subspecies. Our results provide useful resources for modern rice breeding and shed insights for understanding yield and salt tolerance trade-off mechanism. Maintaining yield under environmental stresses is a long-standing but challenging goal of rice breeding. Here, the authors report a MYB transcription factor encoding gene GL12 from wild rice can improve grain length and salt tolerance in cultivated rice and the identification of its upstream regulators GIF1 and WRKY53. [ABSTRACT FROM AUTHOR]

More efficient liberation of valuable minerals from gangue would bring enormous benefits to the comminution process and the downstream beneficiation processes. However, whether particle-bed breakage can improve liberation compared with traditional grinding has been controversial. In this study, three types of iron ores with 3–0.425 mm were comminuted to −0.425 mm via the piston-die compression unit or the dry ball mill at essentially the same grinding degrees. Liberation analysis was performed using Mineral Liberation Analyzer (MLA) for each breakage method and the size fraction product. Statistical methods based on bootstrap resampling and standardized mean differences (SMD) were used to quantitatively analyze the significance of differences in the liberation distribution of iron oxide minerals with different breakage methods. MLA tests showed that the particle-bed breakage did not significantly improve the liberation degree compared to the ball mill grinding; the maximum difference of the proportion of 80–100% liberated iron oxide mineral in a certain size fraction with the two breakage methods was only 5%. The SMD was less than 1.2 in most size/composition classes, which indicated that the difference in the liberation distribution of iron oxide minerals between the two breakage methods was not statistically significant in most size/composition classes. The particle-bed breakage slightly improved the liberation of iron oxide minerals compared to ball mill grinding at the particle size of the products close to the grain size of the iron oxide minerals in the feeds. [ABSTRACT FROM AUTHOR]

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Accurate measurement of bedload is challenging, considering its spatial and temporal variability. Various indirect acoustic techniques are often used for estimating the bedload rate and total bedload mass. Estimating the grain size distribution for a bedload event of relatively short duration, taking the smaller bedload particles into account, is difficult. In the current study, an impact plate with two sensors, namely, an accelerometer and a geophone, is tested in a laboratory flume. Available bedload grains are sorted into different grain size classes, and two sets of experiments are conducted. Single-grain/multigrain particles and mixed-grain particles are considered in the single-class and multiclass experiments, respectively. Three different grain mixtures with variable fineness are fed to the plate in the mixed-grain experiment. The present setup can detect bedload grains from 2.36 to about 150 mm, which is an improvement over other indirect methods. A hybrid analysis methodology to predict the grain size distribution using signals from both sensors is developed. The grain size distributions (GSDs) are estimated with a maximum deviation of 22%, which is expected to improve further with data from longer bedload events. [ABSTRACT FROM AUTHOR]

In order to investigate the temperature rise mechanism of laser cladding assisted by ultrasonic energy field, the multi-field heat flow behavior of laser cladding with or without ultrasonic field assistance is studied.Based on the theoretical analysis of laser-powder interaction and thermal effect of ultrasonic energy field, the coupling equation of laser effective heat input and ultrasonic effective heat conversion is obtained.A numerical model of three-dimensional phase-change heat transfer in laser cladding assisted by ultrasonic energy field is established. The solid–liquid phase change and dynamic evolution of the cladding layer are treated by the apparent heat capacity method and the deformation geometry method respectively. The variations of transient heat and velocity with distance based on laser spot center with or without ultrasonic energy field are studied. The effect of ultrasonic energy field on multi-field coupling of heat flow in laser cladding layer is discussed.Then ultrasonic field-assisted laser cladding IN718 experiment is conducted. The surface temperature of the melt pool is tracked in real time. The evolution law of the microstructure of the cladding layer and the distribution of alloying elements are analyzed.The reliability of the model is verified by analyzing the experimental results.The results show that when the laser cladding time is 2 s, the peak temperature and velocity of the molten pool reach the maximum value, which are 2483 K and 0.316 m/s respectively.Under the action of ultrasonic field, when the cladding time is 1 s, 2 s, 3 s and 3.5 s, the peak temperature of the molten pool increases by 26 K, 38 K, 105 K and 121 K respectively. The velocity of the molten pool reaches the maximum when the ultrasonic field acts for 2 s, which reaches 0.319 m/s.With the continuous application of ultrasonic field, the temperature gradient(G) of the cladding layer decreases gradually, and the solidification rate(R) and cooling rate increase. The ratio of temperature gradient to solidification rate (G/R) decreased.In the test range, the temperature variation of the molten pool surface is basically consistent with the simulation results.Ultrasonic field can promote the transformation of microstructure of IN718 cladding layer from columnar dendrites to equiaxial dendrites. The average minimum grain size of the top, middle and bottom of the cladding layer is reduced by 53.70%, 21.8% and 40.82% respectively. The element distribution of the cladding layer is also more uniform. [ABSTRACT FROM AUTHOR]

The primary objective of this research work is to analyse the effect of double pass on grain refinement during friction stir processing (FSP). The impact of double pass was also assessed on the microstructure, micro-hardness, and tensile strength of the hybrid reinforced aluminum alloy. Field emission scanning microscopy with energy dispersive spectroscopic analysis was used to analyze the grain size distribution as well as the percentage of elements present across the stir zone (SZ) and mode of fracture during the tensile testing. Results show a notable increase in mechanical properties and a huge reduction in grain size when compared to base material (BM). The grain size of SZ in single pass FSP (FSPed-SP) and double pass FSP (FSPed-DP) was reduced to 76.71% and 91.8% in comparison to the BM because repetitive stirring action causes huge dynamic recrystallization. However, peak micro-hardness in FSPed-DP and FSPed-SP was achieved as 30.58% and 22.79% of the BM due to the hall–petch effect. FSPed-DP demonstrated superior ultimate tensile strength and percentage of elongation in contrast to FSPed-SP, which exhibited values of 29.03% and 25% respectively. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are among the most widespread organic contaminants in the environment, and anthropogenic activities can produce PAHs through a variety of pyrogenic or petrogenic means. Knowing the concentrations and sources of PAHs helps evaluate ecosystem health and manage natural resources. In this study, 16 US Environmental Protection Agency priority PAHs were analyzed in water and sediment samples collected from September 2021 to September 2023 in four bay systems along the south and central Texas coast, which are a hotpot of crude oil transportation in the United States. Our results indicated that the total concentration of PAHs ranged from 1.9 to 8.3 ng/mL in surface waters (< 0.5 m) and from 520 to 1257 ng/g in surface sediments (top 5 cm). Grain size analysis revealed that the sediment was dominated by silt (4 - 63 µm), followed by clay (< 4 µm) and sand (> 63 µm) fractions. Both organic carbon and clay content were shown to play a significant role in controlling the PAH content in sediments. Diagnostic ratios indicated that PAHs were primarily sourced via pyrolytic processes, such as the combustion of fossil fuels. Additional sampling at Port Bay, a shallow, secondary bay in the Mission-Aransas National Estuarine Research Reserve, implicated a strong role of resuspension in the distribution and composition of PAHs in the bay systems studied. Overall, these data offer insights into the concentration levels and sources of PAHs in this key region housing oil production and transportation in the United States. [ABSTRACT FROM AUTHOR]

This study investigates the optimization of Laser Powder Bed Fusion (LPBF) process parameters to enhance the mechanical properties of the Russian Ni superalloy VZh159 (a close analogue of IN718) material that is commonly used in critical aerospace applications, and the corresponding studies of the grain structure within and near the melt pool formed by a single laser scan line. Through a factorial experimental approach, the influence of laser power and scanning speed on the tensile strength, yield strength, and ductility was determined. Metallurgically sound samples (based on hydrostatic weighing data and microscopy, with practically no pores detected) were obtained with nine combinations of power and scanning speed, showing significant variation in the tensile strength (in the 1,040–1,220 MPa range) and yield strength (in the 560–1,100 MPa range), which correlated with the cross-sectional area of the single scan line (for example, the depth of the melt pool varied in the range 410–530 µm), while the average grain size (deduced from Electron Backscatter Diffraction (EBSD) images) remained statistically unchanged. Key findings indicate that the optimal LPBF parameters are a laser power of 250 W, a scanning speed of 600 mm/s, and a hatch distance of 0.12 mm, which together yield the best combination of high tensile strength and ductility. This study provides new insights into the effects of LPBF parameters on the microstructure, particularly the formation of the γ ′ strengthening phase and its correlation with mechanical performance. The research addresses a critical gap in understanding the relationship between LPBF processing conditions and the resulting microstructural and mechanical properties, offering potential improvements in manufacturing efficiency and material performance. [ABSTRACT FROM AUTHOR]

Woody debris (WD) stabilizes riverbeds, creates habitats, supports biodiversity, and enhances water quality in ecosystems. This study investigates the impact of WD on sediment characteristics and particulate organic matter (POM) accumulation in the Roztoka stream, located within a forested catchment in the Polish Carpathians. The focus is on the influence of different WD types: coarse (CWD, length > 1 m and diameter > 10 cm), fine (FWD, length < 1 m and diameter < 10 cm), and mixed (MWD, a combination of CWD and FWD) on sediment differentiation and POM accumulation. Stand age, ranging from 20 to over 120 years (in 20-year intervals), was also analyzed as a factor affecting WD structure and POM deposition. Results indicate that MWD had the greatest effect on sediment differentiation, with mean grain size (Mz) ranging from -3.91 phi to -0.95 phi. Stand age significantly influenced POM accumulation, with the highest content (19.51%) observed in age classes III and VI. Older stands (> 120 years) had a diminished effect on both WD structure and POM accumulation. This study underscores the critical role of WD in sediment differentiation and provides insights for improving the ecological function of natural streams. Although the findings are region-specific, they have broader implications for similar temperate mountainous forests. [ABSTRACT FROM AUTHOR]

Living benthic foraminifera, known as environmental bio-indicators of both natural and anthropogenic conditions in marine environments, were investigated in the coastal environment of Roscoff Aber Bay (Brittany, France). Eight sampling sites subject to natural variations (freshwater inputs, tides) and/or anthropogenic impacts (pollution, eutrophication) were studied over four seasons in 2021–2022 (November, February, May, August). We sought to understand the spatial distribution of foraminiferal populations within and between sampling sites over the different seasons and to identify sensitive species and those tolerant to anthropogenic impacts. To this end, sedimentary and biogeochemical characteristics of the sediments were examined by measuring grain size, temperature, oxygen, salinity, pH, environmental pigment concentration (chl a and phaeopigments), total organic carbon (TOC), isotopic ratios of carbon (δ13C), nitrogen (δ15N) and sulfide (δ34S), and chl a fluorescence. Considering these parameters as potential driving factors, four environments were distinguished among the sampling sites: open water, terrestrial, oligotrophic and eutrophic. These showed an increasing gradient of organic supply as well as very different microbial activities, highlighted by carbon and sulfide isotopic ratios. Foraminiferal population study revealed the dominant species characterising these main environments. The lowest abundance but highest diversity of foraminifera was found in the harbour site, associated with the dominance of Haynesina germanica, suggesting this species is tolerant to eutrophic environments and anthropogenic impacts. Open water was dominated by Ammonia beccarii and Elphidium crispum, while Quinqueloculina seminula was the most abundant species in the site with the greatest terrestrial influence. Interestingly, the observed organic enrichment of the harbour due to anthropogenic activities (fisheries, waste deposits, etc.) does not seem to significantly affect foraminiferal diversity. Overall, the benthic foraminiferal species in Roscoff Aber Bay appear to be an excellent proxy for marine environmental conditions under various natural and anthropogenic influences. [ABSTRACT FROM AUTHOR]

Seamounts are ubiquitous topographic units in the global oceans, and the Caiwei Guyot in the Magellan Seamounts of the western Pacific is a prime example. In this study, we analyzed a well-dated sediment core using magnetic properties, sediment grain size, and metal enrichment to uncover regional ventilation history during the middle Pleistocene and explore potential linkages to global climate changes. Our principal findings are as follows: (1) The median grain size is 3.3 ± 0.2 mm, and clay and silt particles exhibit minimal variation, with average values of 52.8 ± 1.8% and 38.2 ± 1.6%, respectively, indicating a low-dynamic process; (2) Three grain-size components are identified, characterized by modal patterns of ~3 mm (major one), ~40 mm, and 400-500 mm, respectively; (3) Magnetic coercivity of the deep-sea sediments can be classified into three subgroups, and their coercivity values are 6.1 ± 0.5 mT, 25.7 ± 1.0 mT, and 65.2 ± 2.1 mT. Based on these results, we propose a close linkage between magnetic coercivity and metal enrichment, correlating with changes in deep-sea circulation intensity. Conversely, sediment grain-size changes seem to be more strongly influenced by eolian inputs. Consequently, we suggest that regional ventilation has weakened since ~430 ka, likely linked to a reduction in Antarctic bottom water formation. [ABSTRACT FROM AUTHOR]

Cesium lead iodide (CsPbI3) exhibits great potential in developing photovoltaic cells due to suitable optical bandgap and thermal stability. However, the photoactive γ‐phase normally exists at high‐temperatures ≈180 °C, and it is challenging to obtain γ‐phase CsPbI3 at room temperature. Here, it discovers that γ‐phase CsPbI3 is achievable by reducing the underlayer surface roughness to a certain level. This method is universal as demonstrated on the surface of poly(3,4‐ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT:PSS), poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA), polystyrene (PS), and silicon substrates. Moreover, it is found that lower surface roughness resulted in smaller crystallite size in the CsPbI3 film, which is an important reason for achieving γ‐phase because the decrease in crystallite size will increase grain surface energy to suppress tilting of PbI6 octahedra and lattice distortion. This study offers a universal approach to obtain γ‐phase CsPbI3 for the development of high‐performance all‐inorganic perovskite solar cells and other optoelectronic devices. [ABSTRACT FROM AUTHOR]

Volcanic ash (tephra) preserved in terrestrial environments and lake sediments contains information about volcanic processes and can be used to infer eruptive parameters and frequency of past eruptions, contributing to the understanding of volcanic hazards. However, tephra deposits can undergo transformation from their initial fallout sedimentation to being preserved as a tephra layer in the sedimentary record. The process is likely to be different in lakes and in terrestrial (soil) sequences. Here we compare the thickness, mass loading and grain size of tephra layers from the 1991 eruption of Cerro Hudson, Chile, from small lakes and adjacent terrestrial settings to measurements of the tephra made shortly after the eruption. We analysed samples from 35 cores in total from six small lakes (<0.25 km2), located 76 and 109 km from the volcano in two contrasting climatic areas (cool and humid northern site, and warm and dry southern site), and made 73 measurements of tephra thickness and 11 measurements of grain size in adjacent terrestrial areas. The major element geochemistry of our samples confirmed they were from the 1991 Hudson eruption. We found that some of the measured characteristics of the preserved tephra layers were comparable to those recorded in 1991 shortly after initial deposition, but that there was considerable variability within and between locations. This variability was not predictable and lake sediments did not preserve a notably more accurate record of the fallout than terrestrial sites. However, in aggregate the characteristics of the preserved tephra was similar to those recorded at the time of deposition, suggesting that, for palaeotephra research, a sampling strategy involving a wide range of environments is more robust than one that relies on a single sedimentary record or a single type of sedimentary environment. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are among the most widespread organic contaminants in the environment, and anthropogenic activities can produce PAHs through a variety of pyrogenic or petrogenic means. Knowing the concentrations and sources of PAHs helps evaluate ecosystem health and manage natural resources. In this study, 16 US Environmental Protection Agency priority PAHs were analyzed in water and sediment samples collected from September 2021 to September 2023 in four bay systems along the south and central Texas coast, which are a hotpot of crude oil transportation in the United States. Our results indicated that the total concentration of PAHs ranged from 1.9 to 8.3 ng/mL in surface waters (< 0.5 m) and from 520 to 1257 ng/g in surface sediments (top 5 cm). Grain size analysis revealed that the sediment was dominated by silt (4 - 63 μm), followed by clay (< 4 μm) and sand (> 63 μm) fractions. Both organic carbon and clay content were shown to play a significant role in controlling the PAH content in sediments. Diagnostic ratios indicated that PAHs were primarily sourced via pyrolytic processes, such as the combustion of fossil fuels. Additional sampling at Port Bay, a shallow, secondary bay in the Mission-Aransas National Estuarine Research Reserve, implicated a strong role of resuspension in the distribution and composition of PAHs in the bay systems studied. Overall, these data offer insights into the concentration levels and sources of PAHs in this key region housing oil production and transportation in the United States. [ABSTRACT FROM AUTHOR]

Granulation is an ancient and sophisticated decorative technique. The production of granules is a crucial part of this process but has rarely been studied. The present study employed three techniques—pouring method, heating method, and crucible method—to produce gold granules. The success ratio of granule formation, granule surface morphology, microstructure, and formation were analyzed to identify the techniques used in archaeological objects. The cooling medium significantly influenced small granule formation, microstructure, and grain size. Both heating and crucible methods could control the granule formation, but these methods produced distinct microstructures. Based on these experimental granules, the probable production methods of ancient gold balls were identified. The present study provided microscopic information for determining ancient gold granule production techniques. [ABSTRACT FROM AUTHOR]

The overall structural integrity and longevity of modern high-performance ship structures are significantly affected by the mechanical properties of plate-beam connectors, which are critical components in these structures. As global maritime strategic needs continue to evolve, understanding the behavior of high-strength steel structures under extreme dynamic loading has become increasingly crucial. This paper investigates the effects of heat input on microstructural evolution and dynamic fracture behavior in 8NiCrMoV high-strength steel T-joints using laser-MAG hybrid welding. A comprehensive multi-scale analysis is achieved through the development of a temperature field model for the laser-MAG hybrid heat source, coupled with high-speed camera and acceleration sensing technology. The results show that T-joints under low heat input (13.81 kJ/cm) exhibit superior dynamic mechanical properties, exhibiting 81.4% higher impact fracture energy and 47.2% greater maximum displacement compared to T-joints welded at 18.62 kJ/cm. The microstructure of weld metal primarily comprises acicular ferrite, granular bainite (GB), and plate-like bainite. Temperature distribution during the laser-MAG hybrid welding indicates that the microstructure gradient and microhardness within the heat-affected zone (HAZ) emerge as key determinants of impact toughness. The higher heat input leads to grain coarsening and precipitation of GB, with a 384.1% increase in average grain size when the heat input rises from 13.81 to 18.62 kJ/cm. The existence of hardenable lath martensite and GB in the HAZ results in reduced impact toughness. Especially under high heat input, the precipitation of these microstructures and high-hardness second-phase particles can cause the initiation and propagation of cracks in the HAZ. [ABSTRACT FROM AUTHOR]

Utilizing well logging data, outcrop profiles, and previous research, this study analyzes the sedimentary and tectonic evolution of the Yan'an Formation in the Ordos Basin, correlating the resulting sedimentary facies with hydrocarbon reservoirs to establish the necessary connections. The study reveals that: (1) Vertically, the sediment grain size shows a pattern of coarser grains at the bottom and top, with finer grains in the middle. Horizontally, the grain size tends to become finer from the northern, western, and southern parts of the basin toward the central-western region. (2) Tectonic movements during the Yan'an period controlled the sedimentary environment. These tectonic activities, through uplift and subsidence, caused the Yan'an Formation to experience four stages of sedimentary environments: braided river, lake, delta, and meandering river. (3) The Yan'an Formation exhibits four types of reservoir sandbody stacking patterns—continuous superposition, intermittent superposition, interbedded sand-mud, and single sandbody types—with continuous and intermittent stacking being the most common. (4) The hydrocarbons in the Yan'an Formation originated from the Chang 7 Member of the Yanchang Formation and migrated into the Yan'an reservoirs. The oil is characterized by its low density, low viscosity, and low pour point, indicating it is a high-maturity, high-quality crude oil. [ABSTRACT FROM AUTHOR]

Herein, films of barium antimonides (BaSb) are fabricated by a thermal deposition technique under a vacuum pressure of 10−5 mbar. BaSb films exhibit orthorhombic lattice. Over a wide range of scans, the films are mostly stoichiometric, displaying atomic contents of 50.17 and 49.83 at% for Ba and Sb, respectively. Morphological analyses of these films show the growth of large grains with sizes ranging from 1.64 to 4.14 μm. Dynamic electrical measurements on Ag/BaSb/Ag films are conducted in the frequency domain of 0.01–1.80 GHz. The films display features of voltage‐controlled negative capacitance source (VCNC) and resonance–antiresonance peaks at a critical frequency of 1.64 GHz. Lorentz models spectral analyses on these peaks indicate that they correspond to a high‐frequency capacitance value of 2.8 nF, a density of oscillators of 4 × 1010 cm−3, and a scattering time constant of τ = 100 ns. Additionally, Ag/BaSb/Ag films show a wide variety in the cutoff frequency spectra, making them suitable for high‐frequency applications. The cutoff frequency varies from 2.6 GHz to 1.0 THz as driving frequency increases from 1.0 to 1.64 GHz. The features of VCNC sources, resonance–antiresonance behavior, and high cutoff frequency make BaSb thin films promising for thin‐film transistors and 6 G technology applications. [ABSTRACT FROM AUTHOR]

Notch development at the base of sea cliffs is an important control on cliff recession rates, but a detailed mechanistic understanding of notch formation by swash abrasion is lacking. We conducted physical experiments, using homogeneous erodible rock simulants, to study notch‐forming mechanisms under periodic sediment‐laden bore impacts. Our findings reveal shifts in the temporal dynamics of notch development. Initially, swash uprush and vortex formation contribute to a positive feedback loop that creates a shallow and wide notch. Subsequently, upward erosion ceases, and notch backwear and downwear are dominated by the vortex. Eventually, sediment deposition armors the notch floor; this negative feedback loop reduces erosion. The sediment size determines the amount of erosion, with a range of grain sizes generating maximum erosion. This indicates a dependence on the momentum of the sediment particles entrained within the bore. This research reveals fundamental notch formation mechanisms driven by swash abrasion. Plain Language Summary: When waves attack a rock cliff, they gradually undercut the cliff and remove materials, forming a wave‐cut notch. Studying how notches form and develop in natural settings takes a very long time, so we created a weaker cliff in the laboratory using easily eroded foam. The cliff was exposed to repeated impacts from bores carrying sediment, representing the impact of broken waves. Notch formation is observed over a few hundred hours. Initially, the notch is wide and shallow. As it grows, abrasive sediment cannot be propelled into the roof, stopping the upward expansion of the notch, and sediment piles up at the bottom, blocking further downward erosion. The notch continues to deepen, but at a decreasing rate. The size of the beach sand or gravel has an important influence on the erosion rate. If the sediments are too large or too small, little erosion occurs, whereas sediments of a certain size can cause rapid erosion. This is because waves need to be able to entrain sediment and hurl it with sufficient force against the cliff to cause erosion. Key Points: Controlled laboratory experiments with repeated swash impacts reveal positive and negative feedback mechanisms in abrasion notch formationNotch geometry varies over time and is determined by swash impact location, vortex formation and sediment depositionGrain size modulates beach shape and sediment‐laden bore momentum, collectively influencing notch development [ABSTRACT FROM AUTHOR]