In this study, zinc-modified biochar (ZBC) was prepared from rose willow, and NiCoMn-LDHs@ZBC composites were synthesized using a hydrothermal method. The composites were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption mechanism of As(V) from aqueous solution onto NiCoMn-LDHs@ZBC was investigated through a series of arsenic adsorption experiments. The effects of various experimental parameters (including adsorbent composition and ratio, adsorbent dosage, solution pH, contact time, temperature, and coexisting ions) on the adsorption capacity were evaluated. Additionally, adsorption model fitting and kinetic analysis were conducted. The results indicate that the adsorption process follows the pseudo-second-order kinetic model (linear correlation coefficient R2 = 0.99), while the isothermal adsorption process adheres to the Langmuir model, with a maximum adsorption capacity of 159.780 mg/g. The adsorption process is primarily dominated by chemisorption and involves three pathways: first, electrostatic attraction between the material surface and arsenic-containing ions; second, ion exchange between arsenic-containing ions and interlayer carbonate ions; and third, coordination reactions between the surface hydroxyl groups (-OH) of NiCoMn-LDHs@ZBC and As, forming As-O-M inner-sphere complexes as adsorption proceeds. Furthermore, the NiCoMn-LDHs@ZBC composite exhibits relatively stable reusability, demonstrating significant potential for the treatment of arsenic pollution in water bodies.
The Oxygen Evolution Reaction (OER) is the bottleneck in the water splitting reaction since it involves four intermediate steps, constituting the adsorption-desorption of oxygen-based radical groups, and not all of them are energetically favorable. Rapidly growing research interest is focusing on carbon-based materials as novel, highly active and durable non-precious electrocatalysts for the OER, representing a valuable alternative to precious and rare materials with electrochemical properties tuned by defect creation. In this work, we propose a facile and green methodology based on the modification of graphene oxide by laser irradiation to obtain an alternative OER catalyst. GO flakes were chemically and physically modified using pulsed laser irradiation at 532nm with fluences of 1.5J/cm2 and 2.5J/cm2. Different analyses were carried out to correlate the electrochemical performance with the structural, optical, and morphological properties; after that, we correlated the improvements in the OER with respect to the pristine GO with the increase in OH functional groups obtained by laser treatment. The best-performing sample exhibited an overpotential of 380mV, comparable to that of catalysts reported in the literature but with the advantage of not being a precious or rare material.
Monohalogen-substituted (F-, Cl-, Br-) phenylethylamine derivates are a valuable class of chiral compounds, e.g., for C-C-coupling reactions, which are the basis for multiple pharmaceuticals and resolving agents. Here, the solid phase behavior of the underlying phenylethylamine derivates, especially of the corresponding hydrochloride salts, is highly relevant as those compounds are often applied in enantiopure form during the production processes. In this study, the solid phase behavior of 20 synthesized chiral phenylethylamine hydrochloride derivates (both enantiomers and racemates) was investigated including detailed information regarding melting behavior, powder X-ray diffraction data and the type of the chiral system present. Further, the binary melt phase diagram of a found conglomerate system and two novel enantiomer crystal structures were determined. This study is aimed at revealing structure-phase behavior relationships for the 20 monohalogen-substituted compounds investigated as well as providing basic solid-phase-related data required for later crystallization-based enantioseparation processes.
Agmatinase (SpeB) catalyzes the hydrolysis of agmatine to produce putrescine, a key step in bacterial polyamine biosynthesis. Here, we report the crystal structure of SpeB from Klebsiella pneumoniae (kpSpeB) and characterize its oligomeric and active-site architecture. SEC-MALS analysis demonstrates that kpSpeB forms a canonical hexamer in solution. Structural comparison reveals high similarity to Escherichia coli SpeB and other members of the arginase superfamily, including proclavaminic acid amidino hydrolase (PAH) and guanidine hydrolase (GdmH). Despite strong conservation of residues coordinating the binuclear Mn2+ center, subtle differences in metal positioning and cavity geometry were observed. Surface analysis indicates variations in active-site cavity volume among homologues, with partial occlusion in GdmH due to a bulky tryptophan residue. These findings suggest that minor adjustments in metal coordination and cavity architecture may fine-tune substrate selectivity while preserving the conserved catalytic framework of the arginase superfamily.
This study presented an application of thermomechanical processing consisting of cold rolling and subsequent annealing in SP2215 heat-resistant steel to investigate the effects of thermomechanical processing parameters on the evolution of grain boundary character distribution (GBCD) and to elucidate the relationship between GBCD and creep properties. The experimental results show that the optimal process, characterized by 10% cold rolling reduction followed by annealing at 1100 degrees C for 10 min, was determined to significantly increase the fraction of low-Sigma coincidence site lattice (CSL) boundaries up to 74.27%, and effectively disrupt the connectivity of the random boundary network, as corroborated by the highest average twin-related domain (TRD) size of 42.58 mu m and average number of grains per TRD of 7.28. Such a modified GBCD leads to a notable enhancement in creep performance, resulting from the induction of a high fraction of low-Sigma CSL boundaries and the disruption of the random boundary network, which effectively inhibits intergranular crack initiation and propagation during creep deformation.
Two zinc(II)-trimesate metal-organic frameworks were synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction. Although both compounds originate from the same Zn(II)-benzene-1,3,5-tricarboxylate (BTC) chemical system, they crystallize in different space groups and exhibit distinct coordination environments and secondary building units (SBUs). One framework adopts a cubic structure and is built from a binuclear Zn paddlewheel type SBU, characterized by a short Zn-Zn internuclear distance and four mu 2-bridging carboxylate groups. In contrast, the second framework crystallizes in a tetragonal lattice and features mixed Zn(II) coordination environments, with the coexistence of tetrahedral and octahedral metal centers assembled into a fundamentally different SBU. The comparison between these two structures highlights the coordination flexibility of Zn(II) and the sensitivity of Zn-BTC frameworks to crystallization conditions, such as solvent composition. These results underline the importance of detailed crystallographic analysis in revealing SBU diversity and provide insight into how variations in local coordination chemistry can lead to distinct framework architectures from identical chemical building blocks.
This study evaluated and compared the mechanical performance of conventionally milled zirconia and two additively manufactured zirconia ceramics fabricated using Lithography-based Ceramic Manufacturing (LCM) technology for potential use in load-bearing dental restorations. A total of 150 zirconia specimens were prepared and allocated into three material groups: milled zirconia and LCM-printed zirconia (LithaCon 3Y 210 and LithaCon 3Y 230), each subdivided into non-aged (control, C) and thermocycled aged (A) conditions (n = 25 per condition). Specimens were standardized using CAD and fabricated by milling or LCM printing. Flexural strength was assessed using a three-point bending test in accordance with ISO 6872:2024, nanoindentation hardness was measured with a Berkovich indenter following ISO 14577-1:2015, and surface roughness was evaluated using optical profilometry per ISO 21920-2:2021. Flexural strength showed no significant differences among groups, while hardness and surface roughness varied significantly. LCM zirconia demonstrated comparable flexural strength to milled zirconia, although milled materials exhibited higher hardness. The 210A group showed the most favorable overall mechanical profile, warranting further investigation of long-term performance.
In this paper, we investigate the absolute stability of several Translationally Invariant Configurations (TICs) observed in cholesteric liquid crystal samples. The bounding plates of the samples may impose homeotropic anchoring (case 1), slightly tilted anchoring when the plates are also rubbed in either the same (case 2) or opposite (case 3) directions, or hybrid anchoring with planar on one plate and homeotropic on the other. In each case, the stability is examined as a function of the confinement ratio—defined as the ratio of the sample thickness to the cholesteric pitch—and of the applied field (electric and/or magnetic).
We develop a theoretical model for the flexoelectric instability in bent-core nematic liquid crystals, focusing on the coupling between elastic distortions and an external electric field through flexoelectric polarization. The analysis is carried out in the nematic phase close to the twist-bend transition, where both the flexoelectric coefficients and the effective bend elastic constant exhibit strong temperature dependence. Within a Landau-de Gennes framework, we derive analytical expressions for the threshold electric field and the corresponding wave vector of the emerging periodic modulation by minimizing the total free energy and assuming K1=K2. Numerical simulations illustrate the temperature dependence of the threshold parameters and the role of dielectric anisotropy and elastic constants. The results indicate that the flexoelectric instability may occur only within a finite temperature interval above the transition into the twist-bend phase and that both the threshold electric field and the periodic structure's wave vector decrease as the temperature decreases.
Carbon fiber-reinforced polymer (CFRP) composites are widely employed in the aerospace industry due to their excellent properties such as high specific strength and corrosion resistance. However, the delamination and tearing of composites are prone to occur in the machining of CFRP, which significantly affect its performance. The existing laser-assisted cutting model generally simplifies the machining process into high-temperature conventional cutting, and only reflects the thermal effect by modifying the material parameters. The core selective ablation characteristics of laser-CFRP interaction are completely ignored, and the unique mechanical behavior of bare fiber under a large cutting angle is not modeled, and the quantitative correlation between cutting force evolution and machining damage is lacking. In this study, an innovative method of partially exposing fibers is proposed to simulate laser-assisted machining. A micromechanical model is developed to analyze the removal mechanisms of different phases during CFRP processing, and a cutting force prediction model from the micro to macro scale is also established. At the micro-scale, a micromechanical model for fiber cutting in orthogonal machining of CFRP is constructed based on the elastic foundation beam theory. The results show that the proposed cutting force prediction model has high reliability, and the relative error between the predicted value and the experimental measured value is only 7.81%similar to 8.99%. All experiments were repeated three times. Statistical analysis showed that the repeatability of the results was excellent. Compared with conventional cutting, laser-assisted cutting fundamentally changed the failure mode of the fiber from matrix-constrained crushing fracture to controllable free-end large-deflection bending fracture. This transformation leads to a smoother and more regular fiber fracture surface, which effectively inhibits fiber breakage, matrix tearing, and fiber-matrix interface debonding. Quantitative analysis confirms that under laser-assisted processing conditions, the matrix tearing length is positively linearly correlated with the cutting depth, cutting speed, and bare fiber length.
Diacetylene monomers are known to undergo solid-state 1,4-addition polymerization when their crystal packing satisfies strict geometric criteria; however, the influence of bulky terminal protecting groups on the lattice adjustments required for bond formation remains insufficiently understood. Here, we synthesized amide derivatives of 2,4-hexadiyne-1,6-diamine, crystallized them via antisolvent vapor diffusion, and evaluated their thermal and photochemical reactivity. Single-crystal analysis shows that Boc-protected monomers (Boc-DA) form hydrogen-bond-directed parallel stacks that align diyne units in geometries nominally consistent with topochemical polymerization, yet they exhibit negligible photoreactivity under ambient UV irradiation. Structural inspection indicates that steric congestion from the tert-butoxycarbonyl termini restricts the subtle axial contraction and molecular shifts required for bond formation. Reducing steric bulk or applying combined thermal and photochemical activation enables polymerization of these diacetylenes. These findings demonstrate that globally favorable packing arrangements can coexist with local steric barriers that impose kinetic constraints on reactivity. Modulating terminal-group size and applying multimodal activation therefore provide a simple and tunable strategy to control diacetylene polymerization, offering design principles for switchable polydiacetylene materials in crystal engineering.
The commercialization of perovskite solar cells (PSCs) hinges on replacing toxic lead-based absorbers with environmentally benign alternatives while maintaining competitive power conversion efficiencies (PCE). However, the enormous parameter space governing lead-free device architectures-spanning absorber thickness, defect density, doping concentration, and charge transport layer (CTL) selection-renders traditional trial-and-error optimization impractical. This paper introduces PerovskiteOpt-AI, a machine learning (ML)-driven multi-parameter optimization framework that integrates SCAPS-1D device simulation with Gaussian process (GP) surrogate modeling and Bayesian optimization (BO) to systematically identify high-efficiency lead-free PSC configurations. A synthetic dataset of 12,000 device-level simulations generated for the FTO/WS2/CsSnI3/CuSCN/Au architecture by varying eight critical parameters. An ensemble of ML models-random forest (RF), XGBoost, and GP regression (GPR)-is trained and benchmarked, with XGBoost achieving an R-2 of 0.9987 and RMSE of 0.041% for PCE prediction. The GP surrogate is then coupled with a BO loop employing expected improvement (EI) acquisition to navigate the design space, converging on an optimized PCE of 27.83% +/- 0.21% within 150 iterations-a 38.6% relative improvement over the baseline. Shapley additive explanations (SHAP) analysis reveals that absorber defect density and perovskite thickness are the dominant efficiency drivers, while conduction band offset at the ETL/absorber interface governs open-circuit voltage. The proposed framework reduces the computational cost of full-factorial parametric sweeps by over 95%, establishing a scalable paradigm for accelerated, interpretable design of next-generation lead-free consumer-grade photovoltaic devices.
This paper investigates the stability of perovskite films under bonding conditions, focusing on the impact of bonding temperature on the electrical, morphological, and elemental characteristics of perovskite solar cells (PSCs) incorporating a barium-strontium titanate (BST) barrier layer. This study aimed to elucidate the interdiffusion phenomena at interfaces and their effect on device performance. We found that increasing the bonding temperature significantly degrades PSC performance, with efficiencies dropping from 21% at 100 degrees C to 65% at 180 degrees C relative to unbonded devices. A critical bonding temperature of 150 degrees C was identified, which correlates with a pronounced drop in short-circuit current and a peak in series resistance, phenomena primarily attributed to severe elemental interdiffusion and defect formation at the interfaces. Morphological (SEM) and elemental (EDS) analyses confirmed the temperature-dependent nature of interdiffusion across the Au/BST/perovskite interfaces. These findings underscore the critical role of bonding temperature in triggering interfacial degradation, a factor that mediates the stability of BST-interfaced PSCs during packaging.
Nickel nanoparticles were synthesized via liquid-phase reduction of NiCl2 & centerdot;6H2O with N2H4 & centerdot;H2O. The efficacy of different dispersing agents in preventing agglomeration was systematically compared, establishing a clear processing-dispersion correlation. Four different types of dispersants were selected to compare their effects on the microstructure and dispersibility of nano nickel powder. Among them, Ni nanoparticles prepared using sodium dodecyl sulfate (SDS) as dispersants exhibit superior microscopic morphology and dispersion. And then, the mass ratio between the precursor and dispersant was systematically optimized, resulting in spherical nickel nanoparticles with controllable particle size and favorable physical properties. When the mass ratio of SDS to Ni salt reached 150%, the prepared spherical Ni nanoparticles had the optimal dispersion and a minimum average particle size of 79 +/- 12 nm. By estimating Nv, the concentration of nickel nanoparticles is about 2.15 & times; 1017 particles cm-3 at this ratio. After thermal treatment, the quality of the samples became stable beyond 415 degrees C with a maximum weight reduction of 6.75% at 150% SDS/Ni-salt ratio, and no residual surface sulfur was detected. The saturation magnetization of Ni nanopowders gently decreased with decreasing dispersant content from 35.3 emu & centerdot;g-1 to 31.6 emu & centerdot;g-1 at 300 K, while soft ferromagnetic behavior was maintained, which is more beneficial for the stability of multilayer ceramic capacitor performance.
Dynamic recrystallization processes are known to significantly affect both the mechanical properties and the microstructure of materials. In this paper, we investigate the influence of discontinuous dynamic recrystallization (dDRX) during deformation at high strain rates (from 104 to 105 s-1) and elevated temperatures in pure aluminum and copper (in the range of 700-800 K for aluminum and 800-1100 K for copper). For this purpose, we propose a theoretical model in which the material is described within the framework of continuum mechanics, plastic deformations are modeled using a dislocation plasticity approach, the equation of state is represented by a neural network, and the microstructure evolution is simulated using the cellular automata method. The model is applied to uniaxial compression and tension of copper and aluminum polycrystals with an initial average grain size of 14 mu m. It is shown that grain refinement occurs in all systems. The average grain size decreases from 14 mu m to 4-5 mu m. The distribution of plastic and total strains in the polycrystals is presented. In all considered systems, deformation localization is observed, and the localization pattern changes due to the nucleation of new grains and grain boundary surfaces during dynamic recrystallization.
Two copper vanadates, MCu(VO3)2Cl (M = Cs, Rb), were synthesized and studied by variable-temperature single-crystal X-ray diffraction in the range up to 700 and 675 K for the Cs- and Rb-containing phases, respectively. The structures are composed of [VO3] chains of edge-sharing VO5 polyhedra and [CuO4Cl] chains of CuO4Cl2 octahedra assembled into a three-dimensional framework. Despite close structural similarity, both compounds differ substantially in thermal behavior: the Cs phase exhibits stronger anisotropy compared to the Rb-containing phase. To interpret the structural dynamics, observed bond lengths were compared with values corrected using the simple rigid-body motion model and with bond lengths obtained from TLS analysis of VO5 polyhedra. It is shown that the observed V-O bond lengths can yield misleading trends, including apparent bond shortening upon heating, whereas rigid-body-corrected values provide a more crystal-chemically consistent picture. In particular, comparison of the observed, SRBM-corrected, and TLS-corrected bond lengths shows that the thermal expansion along the direction of the [VO3] chains is poorly reflected by the observed bond lengths, whereas the corrected bond lengths exhibit much closer agreement with the thermal expansion derived from the unit-cell parameters. For the other directions, such a comparison is hindered by the geometry of the bridging linkages and by the ambiguity associated with the TLS treatment. The results obtained for MCu(VO3)2Cl (M = Cs, Rb) therefore demonstrate the strong influence of bond-length evaluation on the interpretation of structural dynamics.
Broadband antireflective surface technology constitutes a crucial technique in optoelectronic devices, playing a key role in reducing optical losses. Ultrafast laser processing provides a flexible route for fabricating micro-nano structures on metallic surfaces because it enables efficient fabrication, high spatial resolution, and minimal chemical consumption. This study uses a variable-angle scanning strategy to texture the copper surface, produce a series of antireflection arrayed micro-nano structures, and study the spectral reflectance characteristics of the copper surface. The results exhibit that 90 degrees orthogonal scanning favors the formation of an arrayed microcone structure, which shows lower reflectance than the non-orthogonal scanning strategies in the 200-1300 nm band, with a minimum reflectance of 0.94%. The 60 degrees and 45 degrees cross-scanning based on the non-orthogonal strategy favors the formation of microcavity structures, and shows low reflectance in the 1300-2500 nm band, with the maximum reflectance remaining below 5%. Laser-induced periodic surface structures (LIPSS) are observed on the structures fabricated by all strategies. This work demonstrates that the scanning angle itself can be used to switch the dominant surface morphology and thereby tailor the spectral antireflection response, and lies in establishing a clear processing-structure-spectral response relationship for copper surfaces, which provides a designable route for wavelength-selective optical absorption in photothermal conversion, infrared detection, and sensing applications.
This study investigates nanoscale material removal behavior and its correlation with subsurface damage of (100)-oriented beta-Ga2O3 subjected to single-point diamond scratching across a range of normal loads. Using multi-scale characterizations, we elucidate the load-dependent transition from elastic deformation to plasticity-dominated removal and, ultimately, to brittle fracture. Under low-load conditions, beta-Ga2O3 exhibits a fully plasticity-dominated removal mechanism, characterized by smooth groove formation with surface pile-up and a crack-free subsurface containing only dislocations and stacking faults, suggesting that ductile-regime processing is achievable under appropriate mechanical conditions. As the normal load increases, the material enters a ductile-brittle transition regime, where plastic flow coexists with the initiation of micro shear cracks, accompanied by unstable fluctuations in the friction coefficient. Under high-load conditions, extensive brittle fracture becomes dominant, characterized by severe subsurface mixed cracking and large-scale material spalling. This research contributes to a deeper understanding of the machinability of beta-Ga2O3 materials with high hardness and brittleness in ultraprecision surface processing.
Laser assistance offers a promising pathway for high-efficiency and low-damage ultraprecision grinding for difficult-to-machine hard-brittle semiconductors. This study employs atomistic simulation to investigate the surface removal and subsurface damage mechanisms of C-, M-, and A-plane AlN workpieces during single-grit laser-assisted nanogrinding (LAG). The results indicate that LAG reduces material pileup, thereby decreasing the grit-workpiece contact area and grinding resistance. By leveraging laser-induced thermal effects to enhance atomic plastic flow, LAG evidently achieves a higher material removal rate than conventional grinding (CG). Grinding the C-plane along a <11-20> orientation yields the lowest surface roughness, although this improvement is not useful for the M- and A-planes. Tangential force increases linearly with grinding depth in both methods, but LAG exhibits a lower rate of increase. LAG consistently produces lower grinding forces and friction coefficients and results in lower dislocation densities in C- and A-plane AlN workpieces at nearly all grinding depths. The C-plane exhibits the thinnest damage layer, followed by the M-plane, with the A-plane the thickest. Increasing the laser power density lowers the grinding force and enhances the removal efficiency. Optimal power density minimizes subsurface damage and improves surface quality; however, excessive power density exacerbates damage. This work provides valuable insights for developing high-efficiency, low-damage LAG techniques for hard-brittle semiconductors.
TC4 alloy samples were fabricated via selective laser melting (SLM) under different process parameters. The effects of scanning speed and build orientation on the microstructure and corrosion behavior were systematically investigated using optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), and electrochemical measurements. The results show that when increasing scan speed, TC4 alloy consists primarily of alpha/alpha' phases with a minor amount of beta phase, along with grain refinement and a higher fraction of low-angle grain boundaries. In 3.5% NaCl solution, the XOY-oriented sample processed at 1000 mm s-1 exhibited higher impedance and formed a stable, highly protective passive film. In simulated body fluid, the XOY orientation at 1200 mm s-1 displayed a larger capacitive arc, indicating superior corrosion resistance. These findings demonstrate that the corrosion performance of SLM-processed TC4 alloy can be optimized for specific service environments by tailoring both process parameters and build orientation.
