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The in situ growth dynamics of colloidal silver–gold core–shell (Ag@Au CS) nanoparticles (NPs) are studied using time-dependent second harmonic generation (SHG) and extinction spectroscopy. Four sequential additions of chloroauric acid, sodium citrate, and hydroquinone are added to a silver nanoparticle solution to form a gold shell around a 45 nm silver core under different reaction conditions, resulting in final sizes ranging from 80 to 125 nm in diameter. In the first addition, a bumpy, urchin-like surface morphology is produced, while the second, third, and fourth additions provide additional nanoparticle growth with the surface morphology becoming more smooth and uniform, as shown using transmission electron microscopy measurements. The in situ extinction spectra increase in intensity for each addition, where blue-shifting and spectral narrowing are observed as the Ag@Au CS NPs grow in size. The extinction spectra are compared to Mie theory simulations, showing general agreement at later stages of the reactions for smooth CS surfaces. The in situ SHG signal is dominated by surface-enhanced plasmonic hotspots at the early stages of the shell growth, followed by gradual decreases in signal as the surface becomes more smooth. Two-photon fluorescence is also monitored during the CS growth, showing complementary information for comparisons to the extinction and SHG results. The holistic study of the synthesis and characterization of Ag@Au CS nanoparticles using in situ SHG spectroscopy, extinction spectroscopy, and Mie theory simulations allows for a comprehensive analysis of the complex growth dynamics occurring at the nanoscale for developing optimized plasmonic nanomaterial properties. [ABSTRACT FROM AUTHOR]

Nonpolar (100), polar (002), semipolar (101), and nonpolar (110) preferred oriented ZnO films were synthesized by regulated growth using the chemical bath deposition method. The crystallinity, surface morphology, and optical properties of ZnO films with different preferred orientations after annealing in different atmospheres were systematically investigated. The experimental results show an increase in crystallinity and a decrease in surface roughness of the films after annealing; in particular, the optical transmittance of semipolar (101) preferred oriented ZnO films was significantly higher than that of the other samples. XPS and PL spectra confirmed that annealing in argon effectively increased donor defects, whereas annealing in oxygen and ozone reduced donor defects in the films, and that ozone annealing was best suited to enhance acceptor defects in nonpolar (110) preferred oriented ZnO films. Argon annealing is the best for the enhancement of donor defects in polar (002) preferred oriented ZnO films. This work achieves modulation of optical properties and defects of ZnO films by annealing in different atmospheres, which provides new ideas for the application of ZnO materials. [ABSTRACT FROM AUTHOR]

In this study, Pb(Zr0.54Ti0.46)O3 films were prepared by the sol-gel method with Sm doping concentrations of 0, 0.5, 1, 1.5, 2, and 3 mol. %. Their surface morphology, density, crystal structure, piezoelectric, dielectric, and ferroelectric properties were characterized. The results indicated that, unlike Sm-doped lead zirconate titanate (PZT) ceramics, all Sm-PZT films exhibit a significant increase in the grain size compared to undoped PZT films. Moreover, Sm doping affected their crystal orientation and significantly enhanced their piezoelectric coefficient d33 and remnant polarization (Pr). Notably, the Sm-PZT film with a doping concentration of 1.5 mol. % exhibited optimal (100) orientation, achieving a high piezoelectric coefficient d33 of 279.87 pm/V, 4.55 times that of the non-doped PZT films. [ABSTRACT FROM AUTHOR]

We conduct molecular dynamics simulations of helium in tungsten to study the interaction of helium with grain boundaries. Model systems with grain boundary planes perpendicular to the surface and parallel to the surface are considered. The net attraction of mobile helium to the grain boundary results in a "depleted region" within approximately 3.5 nm of the grain boundary plane at low fluence, and once on the plane of the grain boundary, helium transport slows considerably. Helium retention is also strongly affected by the grain boundaries and their density: grain boundary planes approximately 6 nm beneath the plasma-facing surface and parallel to the surface tend to reduce the maximum bubble size due to the attraction of mobile clusters to the grain boundary plane, which lowers the concentration of helium near the surface (where it is being implanted); grain boundaries perpendicular to the surface tend to increase retention due to retention on the grain boundary plane. For grain boundaries parallel to the surface, the strong gettering effect of the grain boundaries on helium results in essentially no helium penetration through the grain boundary during the first 1.5 μs of plasma exposure at a flux of 1.6 × 10 25 m − 2 s − 1 , corresponding to fluences on the order of 10 20 m − 2 . Coarse-grained simulations capable of capturing the long-term dynamics of helium aggregation near grain boundaries would be required to determine whether these effects would have any measurable impact on phenomena, such as tungsten fuzz growth. [ABSTRACT FROM AUTHOR]

We report about metalorganic vapor phase epitaxy of smooth nitrogen-polar AlN templates on vicinal (0001) sapphire substrates. The influence of the V/III ratio, growth temperature, growth rate, as well as sapphire-nitridation time and temperature, were studied. With 4° offcut sapphire, step-flow growth was possible only with V/III ratios below 2. However, the optimal V/III ratio required precise adjustment, possibly dependent on reactor history and geometry. A rather narrow temperature window of less than 40 °C existed for smooth surface morphology. Reducing the temperature affected adatom mobility, eventually disrupting step-flow growth; increasing the temperature favored the formation of high-aspect-ratio defects on the epilayer. A low thermal-budget nitridation step with a short nitridation time of 15 s proved to be effective in controlling polarity without inducing excessive surface damage on the sapphire substrate. The growth rate also influenced surface morphology, with an increase in RMS roughness and step-bunching for faster growths until at growth rates above 1.4 μm/h step-flow growth could no longer occur. Finally, we developed a V/III ratio fine-tuning procedure, whereby the reactor-specific value that induces optimal growth is inferred by growth-rate variations. With this method, N-polar AlN templates with sub-nanometer RMS roughness were demonstrated for both 4° and 2° offcut sapphire substrates. [ABSTRACT FROM AUTHOR]

Face-to-face annealed and sputter-deposited aluminum nitride (FFA Sp-AlN) has potential in deep-ultraviolet light-emitting devices. Herein, the effects of the substrate off-cut angle (θsub) from an r-plane sapphire toward the c-axis projection direction and sputtering temperature (Tsp) on the crystallinity and surface morphology of a-plane AlN films are investigated. Increasing θsub in the minus-off direction, which occurs when the substrate surface approaches the sapphire c-plane, and lowering Tsp suppress the mixing of anomalous non-a-direction oriented domains. This reduced mixing enhances the surface flatness and crystallinity of a-plane FFA Sp-AlN. Moreover, the c-axis direction of the a-plane AlN film is inverted depending on the substrate off-cut angle. Ab initio calculations indicate that the interface stability between the r-plane sapphire substrate and the a-plane AlN film can explain the dependence of the crystallinity and c-axis orientation of FFA Sp-AlN on the surface off-cut of the r-plane sapphire. [ABSTRACT FROM AUTHOR]

Identifying the oxidation structure of two-dimensional interfaces is crucial to improve surface chemistry and electronic properties. Beyond graphene with only phenyl rings, a novel carbon-nitrogen material, C3N, presents an intrinsic heterogeneous surface morphology where each phenyl ring is encircled by six nitrogen atoms, yet its atomistic oxidation structure remains unclear. Here, combining a series of density functional theory calculations and ab initio molecular dynamics simulations, we demonstrate that thermodynamically favorable oxidation loci are confined to the phenyl ring, and kinetic transformations of oxidation structures are feasible along the phenyl ring, whereas those toward nitrogen atoms are proven to be extremely difficult. These results are attributed to the lower barrier of oxygen atom migration along the phenyl ring, while the significantly high barriers toward nitrogen atoms are due to the heterogeneous potential energy surface for oxygen–C3N interaction. This work highlights the significance of surface morphology on the characteristics of oxidation structure, offering insights into tunable electronic properties via confined interfacial oxidation. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate the in situ characterization of optical micro/nano fibers (MNFs). The MNF (test fiber, TF) is positioned on a microfiber (probe fiber, PF) and simulated for the scattering loss at various PF and TF diameters. The TF is fabricated using chemical etching technique. The PF is a conventional single-mode fiber with an outer diameter of 125 μ m. We measure the scattering loss along the TF axis at various positions i.e., diameters by mounting it on the PF. The diameter profile of the TF is inferred from the measured scattering loss and correlated with its surface morphology measurement. This work demonstrates an effective, low-cost, and non-destructive method for in situ characterization of fabricated MNFs. It can detect and determine the irregularities on the surface of OMNFs. It can also be used to quantify the local evanescent field. Detecting such local points can improve studies that are carried out using these fields in various sensing and related study domains. It is simple to implement and can be accessed by all domains of researchers. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate an in situ etch technique for β-Ga2O3 inside a metalorganic chemical vapor deposition (MOCVD) reactor using triethylgallium (TEGa) as the etching agent. At sufficiently high substrate temperatures (Tsub), TEGa is introduced into the MOCVD reactor which undergoes pyrolysis, resulting in the deposition of Ga on the β-Ga2O3 surface. These Ga adatoms react with Ga2O3 to form gallium suboxide (Ga2O), which desorbs from the β-Ga2O3 surface resulting in the etching of the epilayer. MOCVD chamber parameters such as TEGa molar flow rate, substrate temperature, and chamber pressure were shown to be key in controlling the etch rate and surface morphology. A wide range of etch rates from ∼0.3 to 8.5 μm/h is demonstrated by varying the etch parameters. In addition, smooth surface morphology on (010) and (001) β-Ga2O3 substrates is also demonstrated. This new etch technique could enable damage free fabrication of 3D structures like fins and trenches, which are key components in many β-Ga2O3 device structures. [ABSTRACT FROM AUTHOR]

We investigated the chemical beam epitaxy of GaP 1 − x N x grown on nominally (001) -oriented Si substrates, as desired for the lattice-matched integration of optoelectronic devices with the standard Si technology. The growth mode and the chemical, morphological, and structural properties of samples prepared using different growth temperatures and N precursor fluxes were analyzed by several techniques. Our results show that, up to x ≈ 0.04 , it is possible to synthesize smooth and chemically homogeneous GaP 1 − x N x layers with a high structural quality. As the flux of the N precursor is increased at a given temperature to enhance N incorporation, the quality of the layers degrades upon exceeding a temperature-dependent threshold; above this threshold, the growing layer experiences a growth mode transition from 2D to 3D after reaching a critical thickness of a few nm. Following that transition, the morphology and the chemical composition become modulated along the [ 110 ] direction with a period of several tens of nm. The surface morphology is then characterized by the formation of { 113 } -faceted wires, while the N concentration is enhanced at the troughs formed in between adjacent (113) and (1 ¯ 1 ¯ 3). On the basis of this study, we conclude on the feasibility of fabricating homogeneous thick GaP 1 − x N x layers lattice matched to Si (x = 0.021) or even with N content up to x = 0.04. The possibility of exceeding a N mole fraction of 0.04 without inducing coupled morphological–compositional modulations has also been demonstrated when the layer thickness is kept below the critical value for the 2D–3D growth mode transition. [ABSTRACT FROM AUTHOR]

This work highlights the influence of surface properties, on the characteristics of InAlN/GaN based high electron mobility transistor (HEMT) structures grown on the SiC substrate by metalorganic vapor phase epitaxy. The growth parameters, i.e., reactor pressure and V/III ratio were tuned to improve the morphological and two-dimensional electron gas (2DEG) characteristics of the HEMT structure. It was found that V/III ratio plays a significant role in improving surface morphology and 2DEG properties without altering average indium composition. It was also found that 2DEG properties are highly sensitive to surface morphology and its features. The step flow smooth surface morphology with very low surface and interface roughness was observed in optimized lattice-matched InAlN/GaN HEMT structures. The sheet resistance of ∼170 Ω/sq with good 2DEG concentration (∼2.4 × 1013 cm−2) and 2DEG mobility (∼1500 cm2/V s) was achieved in the optimized lattice-matched InAlN/GaN HEMT structure. A comparison between different barrier-based HEMT structures, i.e., lattice-matched InAlN/GaN and strained AlGaN/GaN, was also discussed. Their structural, electrical, morphological, and interfacial characteristics were compared. [ABSTRACT FROM AUTHOR]

Aramid fiber–reinforced polymer composite (AFRPC) is popular in aerospace and defense industries owing to its superior thermal and mechanical properties. However, its intricate hexagonal cellular structure and the material's heterogeneous, soft, and brittle characteristics lead to significant surface defects, such as burr formation, wall tearing, roughness, dimensional inaccuracies, and uncut fibers during traditional machining. Such poor machining quality issues notably affect the operational lifespan and functional performance of its sandwich structural components. To address these issues, the rotary ultrasonic assisted machining (RUSAM) process has been introduced. To thoroughly investigate the RUSAM of AFRPC using various cutting tools, a 3D finite element model was developed and validated. This paper mainly investigates the effect of various machining parameters such as vibration amplitude (VA), cutting width (CW), feed rate (FR), and spindle speed (SS) on the cutting force, surface morphology, burr formation, and burr height during RUSAM of AFRPC structure by plane and toothed disc cutters. The burr height was found to decrease with the increase of spindle speed (60.82% and 71.00%) and vibration amplitude (78.15% and 82.32%), whereas increase with cutting width ( 149.81 % and 321.16%) and feed rate (156.53% and 314.83%) during RUSAM by plane and toothed disc cutters, respectively. The pattern of variation of burr height with machining parameters was found similar to that of the cutting force. Significance analysis based on 4 levels, 4 factors orthogonal L 16 ( 4 4 ) experiments revealed the cutting width to be the most influential parameter on the burr height and cutting force followed by the spindle speed, feed rate, and vibration amplitude during RUSAM of the AFRPC core by the disc cutters. Up to 62.54 % reduction in burr height was realized by rotary ultrasonic assisted machining compared to the conventional machining. Under specified operating conditions, the disc cutter generates a higher but less number of burr as compared to the toothed disc cutter without any tearing defects. 3–10% and 5–20% burrs were observed during rotary ultrasonic assisted machining compared to 20–50% and 40–70% burrs during conventional machining of AFRPC structure by plane and toothed disc cutters, respectively. This experimental research will be extremely useful to comprehend the burr formation mechanism and optimize the machining parameters for enhanced surface morphology of AFRPC structures. [ABSTRACT FROM AUTHOR]

In this study, reduced graphene oxide (rGO) coatings were fabricated on duplex stainless steel (DSS) substrates using the electrophoretic deposition (EPD) method to evaluate their hydrogen resistance performance. The successful fabrication of rGO coatings was confirmed using Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS). The structural characteristics were characterized using Raman spectroscopy and X-ray Diffraction (XRD). The results indicate that the EPD voltage is a crucial factor affecting the surface quality of and hydrogen resistance performance of rGO. Lower voltages resulted in lower degrees of rGO reduction and higher surface wrinkle density, while higher voltages caused bubble formation, significantly degrading the coating quality and hydrogen resistance performance. The optimal hydrogen resistance was achieved at an EPD voltage of 7.5V and a deposition time of 6 min. Electrochemical hydrogen charging tests and thermal desorption analysis (TDA) demonstrated that rGO coatings prepared under optimal conditions exhibited excellent hydrogen resistance efficiency, significantly reducing hydrogen atom penetration in hydrogen environments. The study further revealed that bubble formation significantly reduces the hydrogen resistance of rGO, which is attributed to increased interlayer spacing and the loss of the "labyrinth effect". • Electrophoretic deposition (EPD) method can effectively reduce graphene oxide. • Optimal EPD parameters were identified for rGO coatings to enhance hydrogen resistance. • RGO coatings reduced hydrogen penetration by preserving a dense multilayer structure. [ABSTRACT FROM AUTHOR]

Previous results clearly confirmed that the presence of an Al plating layer promotes the development of a dense Al 2 O 3 barrier layer when exposed to high temperatures. This enhances the structural stability and improves the oxidation resistance of the dual ceramic coating. In the work, a continuous study was conducted to investigate the effect of varying Al plating layer thickness on the high-temperature oxidation characteristics of a CoCrNiAlY–YSZ–LMA dual ceramic coating. The results indicate that, compared to samples lacking Al layers, all Al-coated samples exhibit dense surface morphology, effectively inhibiting the permeation of O 2. This results in slower growth of the TGO and minimal elemental diffusion. However, significant differences are observed in structural damage. Al layers of 5 μm and 10 μm thickness show slight local fracture damage and good structural stability. In contrast, the 15 μm Al-coated samples experience more severe structural fracture damage within the YSZ layer, including transverse cracking. These potential oxidation and structural damage mechanisms of the coatings with varying Al plating layer thickness were systematically discussed. [ABSTRACT FROM AUTHOR]

This study, magnetic basic resin (MBR) was synthesized by radical polymerization and modification. Its functional groups, surface morphology, elemental composition, and magnetic value were determined by ATR‐FTIR FE‐ESEM, EDX, and VSM techniques. Subsequently, the usability of MBR as an adsorbent in the simultaneous adsorption of Tartrazine (Tart) and Reactive Blue‐4 (RB4) dye binary mixtures were examined. Maximum adsorption for both dyes, (170 mg/g for Tart and 184 mg/g for RB4), was observed under acidic conditions at a pH range of 1.5–2. It was determined that the adsorption of both dyes onto MBR occurred in a monolayer, and the saturation time was 90 min for Tart and 60 min for RB4. The adsorption of both dyes fitted the pseudo‐second‐order kinetic model. It was also concluded that intra‐particle diffusion was effective. Based on the thermodynamic parameters, it was concluded that the adsorption proceeded spontaneously and endothermically, additionally, the calculated E values led to the conclusion that electrostatic interactions dominated the adsorption of Tart and RB4. The MBR exhibited a notable affinity for Tart and RB4, even within a dense matrix containing both anions and cations. Furthermore, it maintained this high removal affinity across four consecutive uses, involving adsorption and desorption processes. [ABSTRACT FROM AUTHOR]

Diamond rope saws are one of the important tools for cutting large structures in deep water, and exploring their ability to remove steel materials is a prerequisite for improving cutting efficiency. In this paper, based on the observation results of an optical profilometer on the surface morphology of diamond beads, using statistical theory to analyse the data on the spatial parameters of abrasive grains, a method of three-dimensional digital characterisation of diamond beads based on the spatial description of the coordinate system of the column is proposed. Based on the above research, the theoretical models for material removal prediction and the finite element simulation model of diamond bead cutting steel material are established to analyse the removal ability of steel material under different cutting conditions with the synergistic effect of multiple abrasive grains in the process of diamond beads cutting steel material. Experiments were used to perform error analysis on the theoretical model, optimise the cutting parameters and correct the theoretical model for material removal. The results show that the cutting speed of 21 m/s and the feed speed of 1 mm/min resulted in a low theoretical and real removal error and less bead wear, which is favourable for continuous cutting. This current work provides a theoretical basis for the intelligent monitoring of the cutting process state of underwater diamond rope saws. [ABSTRACT FROM AUTHOR]

This paper proposes a strategy to overcome the problem of poor surface quality when grinding difficult-to-cut materials at a small scale, by creating a small-scale grinding tool with a regular array structure (SSGT-RAS) through the method of combining low-speed wire electrical discharge turning (LS-WEDT) machine technology and electroplating process. A numerical model is established to describe the surface topography of SSGT-RAS grinding of titanium alloy Ti-6Al-4V, taking into account the shape, size and distribution of the abrasive grains, the plastic material removal mechanism and the machining parameters. The study comparatively analyses the surface morphology characteristics and surface generation mechanism of SSGT-RAS and ordinary cylindrical grinding tool (OCGT) when grinding titanium alloy Ti-6Al-4V with different helical groove depths through side dry grinding experiments. The experimental results show that SSGT-RAS improves the surface quality of the workpiece compared to OCGT, and surface roughness Ra can be reduced by up to 25.20 ~ 27.81% and 21.49 ~ 35.44% at most by changing the feeding velocity and cutting depth, respectively. In addition, increasing helical groove depth further improves the surface quality. A comparative analysis of the simulation and experimental results shows that the prediction error of the surface roughness Ra is within 15.92%. This research expands the preparation process of surface-structured grinding tool at small scale, which has significant theoretical and engineering applications. [ABSTRACT FROM AUTHOR]

Durable superhydrophobic fabrics with electromagnetic wave absorption were highly valuable in practical applications. In this work, durable superhydrophobic cotton fabrics with electromagnetic wave absorption were successfully prepared by modifying the cotton fabrics with polydopamine (PDA) and then depositing MoS2/RGO (MR) composites and polydimethylsiloxane (PDMS). The surface morphology, crystal structure, and thermal degradation properties of the obtained products were evaluated. The PDA modification enhanced the affinity and adsorption saturation between the fabrics and the MR composites. Here, the MR composites provided the fabrics with wave-absorbing components and rough micro/nanostructure, and the PDMS offered lower surface energy for the treated fabrics. Ultimately, the water contact angle (WCA) of the obtained cotton fabrics could reach 157.2 ± 0.4 ° and the minimum reflection loss (RLmin) was −45.3 dB at 11.1 GHz, which showed excellent superhydrophobicity and microwave absorption properties. In addition, the obtained cotton fabrics displayed excellent robustness against rubbing, bending, and laundrying and satisfactory chemical stability. This research showed promising prospects for the development of wearable materials with durable electromagnetic wave absorption. [ABSTRACT FROM AUTHOR]

In this study, cryogenic‐temperature formal machining technique was used to process solution‐treated aluminum 7075 alloys, the mechanical properties, morphology, and microstructure of machined surface and produced chips are investigated. Results show machining temperature has a huge influence on chip and machined surface morphology, cryogenic‐temperature machining chips and machined surfaces possess better surface integrity, chips are continuous and smoother, and machined surfaces are flatter. In contrast, room‐temperature formal machining chips exhibit serrated cracks on their free surface and the machined surface produces more serious scaly spines phenomenon. Both cryogenic‐temperature and room‐temperature samples experience severe deformation, cryogenic‐temperature machining alumium 7075 alloys max microhardness has enhanced from 98 HV 0.1 to 174 HV 0.1, and cryogenic‐temperature samples’ microhardness is higher than corresponding room‐temperature samples’ microhardness among all machining parameters. Cryogenic‐temperature can effectively suppress dynamic recovery thus chips could store more dislocations and then possess smaller ultrafine‐grained structures, accounting for higher microhardness. Besides cryogenic‐temperature inhibits precipitation of solute cluster and second phase particles and plays a lubrication effect at tool‐chip interface, thus cryogenic‐temperature machining aluminum 7075 alloys could obtain superior machined surface quality/chip morphology to improve processability. (*: Equal contributi) [ABSTRACT FROM AUTHOR]

This article examines the evolutionary behavior of transverse surface cracks in Q345 steel during the hot‐rolling process under various rolling conditions. “V”‐shaped cracks are prefabricated on the billet surface for laboratory hot‐rolling tests, and a corresponding rolling model is developed to validate its accuracy. The slab rolling model is established based on actual onsite rolling process parameters. The aim is to analyze the effects of different rolling conditions on the surface crack morphology and aspect ratio. The results indicate that variations in roll diameter (1400, 1300, and 1200 mm) influence crack propagation, with cracks unfolding earlier when the roll diameter is 1400 mm. At varying initial rolling temperatures (1300, 1200, and 1100 °C), cracks begin to unfold earlier at the highest temperature of 1300 °C. When examining different friction coefficients (0.4, 0.5, and 0.6), cracks unfold earlier at the highest coefficient of 0.6. Similarly, at different rolling speeds (3, 4, and 5 m s−1), cracks unfolded earlier at the highest speed of 5 m s−1. Analysis of changes in crack depth and aspect ratio during rolling shows that the initial few passes have a greater influence on crack depth and unfolding. In the later stages of rolling, cracks continue to unfold, though the depth shows minimal variation, and the aspect ratio tends to approach zero. [ABSTRACT FROM AUTHOR]

ABSTRACT In order to attain improved mechanical properties of the carbon fiber (CF) reinforced polyoxymethylene (POM) composite, maleamidic acid treated carbon nanotube (CNT) was deposited on carbon fiber. The mechanical properties of composites have been investigated. The tensile strength values of the treated CF/POM composites at all CNT mixing ratios are found to be higher than that of untreated one. The surface morphologies of the fractured surfaces of the composites were recorded using scanning electron microscopy (SEM) to gain information about the fiber–matrix interfacial adhesion in the composites. The friction coefficient of all the CF/POM/CNT composites decrease as the load increases from 10 to 20 N under the same sliding speed of 1000 r/min. XPS results showed that the formation of C–O, C=O, and O–C=O based species give rise to chemical bonds of the CF and the POM. [ABSTRACT FROM AUTHOR]

Although hydrogen represents a vital source of clean energy, the development of cost-effective, durable materials for use as catalysts in the hydrogen evolution reaction (HER) remains a challenge. In this work, covalent organic framework (COF) - derived core-shell microspheres were prepared as novel electrocatalysts. The previously prepared COF microspheres were pyrolyzed into nitrogen-doped porous carbon (N–C) as the core for enhanced electrocatalytic conductivity. With the assistance of a dual-ligand, the COF shell grew on the surface of N–C to form a core-shell microsphere, which was named N–C@COF. The surface morphology and core-shell structure of N–C@COF were characterized by SEM and TEM. FT-IR, TGA, and XPS were utilized to ascertain the synthesis of COF and the composition of the core-shell microspheres. The N–C@COF core-shell microspheres exhibited excellent HER performance in 1 M KOH electrolyte, demonstrating a low overpotential of 104 mV @ 10 mA cm−2, significantly outperforming pure COF and N–C. Furthermore, the N–C@COF demonstrated excellent HER stability over a 24 h period and retained its HER activity following 2000 consecutive cycles of electrolysis. The presence of the N–C core in the N–C@COF enhanced the electrical conductivity of the catalyst, while the COF shell provided abundant active sites for the HER, resulting in a synergistic improvement in the catalytic efficiency. This work presents a straightforward strategy for synthesizing COF-based multicomponent core-shell microspheres, which provides a promising pathway for the development of available and cost-effective electrocatalysts. [Display omitted] • COF-derived carbon microspheres as cores. • The N–C core significantly improves the electrical conductivity. • COF shells provide a large number of active sites for HER. • N–C@COF exhibited a low over-potential of 104 mV @ 10 mA cm−2. [ABSTRACT FROM AUTHOR]

The homochirality of life remains one of the most enigmatic issues in the study of the origin of life. A proposed mechanism for symmetry breaking involves irradiation by circularly polarized light (CPL). To investigate the photoreaction of amino acids under CPL irradiation, a vacuum ultraviolet (VUV) CPL irradiation system was developed at the synchrotron light source UVSOR‐III. Hydrogen Lyman‐α CPL (121.6 nm) is considered a potential asymmetric source in space. Therefore, racemic alanine film samples were irradiated with Lyman‐α CPL to explore the photoreaction of biomolecules. Circular dichroism (CD) spectra measurements revealed that irradiation with right‐ (left‐) handed CPL induced a positive (negative) anisotropy factor g in the wavelength range of 180–240 nm. However, the spectra differed from those of enantiopure alanine, exhibiting broad wavelength ranges and no sign change. Liquid chromatography‐mass spectrometry (LC–MS) measurements indicate formation of larger molecules, such as oligomeric alanine adducts or modified oligomers after the Lyman‐α CPL irradiation. Additionally, CPL irradiation considerably changes the microstructure of the alanine film surface, leading to the formation of circular network aggregates on the scale of 100 nm. The morphology changes in the alanine film and/or the formation of the larger molecules could be possible causes of the modified anisotropy factor spectra compared to those of enantiopure alanine. These findings highlight the need for further research on the photoreaction of biomolecules in solid states under VUV CPL irradiation, particularly in the photoionization energy range, to validate the cosmic scenario of homochirality. [ABSTRACT FROM AUTHOR]

Laser peen forming (LPF) is an appealing technique for forming metal sheets using high-energy, shortduration laser pulses. The deformation of the target metal plate is closely related to the magnitude and distribution of laser-induced residual stress. Consequently, the relationship between process parameters and residual stress is worth researching. In this research, two process parameters in LPF, laser energy and coverage ratio (spot distance essentially), and one workpiece parameter, plate thickness, were examined through an element method (FEM) of multiple square-spot laser shock peening (SSLSP). Corresponding experiments of SSLSP on aluminum alloy 2024-T351 test blocks were conducted, together with an X-ray diffraction (XRD) residual stress measurement and a surface morphology observation. The FEM simulation and experimental results show that congested laser spots had a significant influence on the magnitude of compressive residual stress; higher laser energy was beneficial to the depth of the compressive stress layer but could decrease its magnitude. Therefore, for better forming ability, higher laser energy and a higher coverage ratio are beneficial; for surface strengthening, laser energy should not be too large, and the coverage ratio should be larger than 100% to ensure that the residual stress on the treated surface is compressive, resulting in better surface integrity. [ABSTRACT FROM AUTHOR]

The metal‐organic vapor phase epitaxy (MOVPE) method faces several challenges when used for the growth of N‐polar GaN on foreign substrates, including the presence of a rough surface morphology characterized by step bunching or hexagonal hillocks. In this study, it is aimed to address these issues by establishing optimal growth conditions for the MOVPE method, enabling the growth of N‐polar GaN/Al0.9Ga0.1N/AlN heterostructures with a smooth surface morphology on a vicinal sapphire substrate. The formation of 2D electron gas (2DEG) in N‐polar GaN/AlGaN/AlN prepared using MOVPE is discussed. Additionally, in the study, the impact of growth conditions, such as temperature and V/III ratio, on the electrical properties of N‐polar GaN is investigated. In the results, it is revealed that growth at lower temperatures and a V/III ratio of 30 000 effectively suppresses 3D growth. Moreover, an increase in the V/III ratio correlates with a decrease in residual impurity concentrations (C and H); hence, electron mobility improves. Moreover, the N‐polar GaN/AlGaN/AlN field‐effect transistor, grown under optimized conditions, exhibits a higher maximum drain–source current (IDmax). In these results, possibilities are broadened for the high performance of N‐polar GaN channel high‐electron‐mobility transistors through MOVPE. [ABSTRACT FROM AUTHOR]

Selective area growth and epitaxial lateral overgrowth (ELOG) of semipolar (11¯$1 \left(\right. \macr \left.\right)$01) GaN stripes are demonstrated on a trench patterned vicinal (001) Si substrate fabricated by a maskless photolithography‐based process. High precision alignment enables selective mask formation to one sidewall of the trench. Selective area growth of GaN stripes is conducted from the (111) plane sidewall of Si, and ELOG region reaches ≈13 μm. The ELOG GaN crystal is dislocation‐free at most areas. The semipolar GaN stripes with atomically flat surface morphology are uniformly obtained. Light‐emitting diode structures with InGaN/GaN multiple quantum wells are grown on the 13‐μm ELOG (11¯$1 \left(\right. \macr \left.\right)$01) GaN stripes and a single photoluminescence emission peaked at 485 nm is obtained, suggesting potential for the cost‐effective semipolar micro light‐emitting diode fabrication technologies. [ABSTRACT FROM AUTHOR]

High crystalline quality and flat a‐plane aluminum gallium nitride (AlGaN) films are obtained on Si‐doped AlN templates with a moderate silane (SiH4) flow rate by metal‐organic chemical vapor deposition (MOCVD). The effects of the SiH4 flow rate on the surface morphology, crystalline quality, stress state, and optical property of a‐plane AlN templates and AlGaN films are comprehensively investigated. As the SiH4 flow rate increases from 0 to 7.0 nmol min−1, the full width at half maximum of X‐ray rocking curve values along [0001]/[1–100] directions for the AlGaN films are monotonically reduced to 1124/1143 arcsec. Meanwhile, the surface root mean square roughness value is decreased to 0.88 nm. These achievements are attributed to the suppression of the anisotropy degrees and in‐plane stress of AlN templates. In addition, an excess SiH4 flow rate leads to deteriorated surface morphologies and increased basal plane stacking fault (BPSF) densities for both AlN and AlGaN films. This work suggests that doping AlN layers with an appropriate SiH4 flow rate is a promising route to obtain high‐quality a‐plane AlGaN films for efficient nonpolar deep ultraviolet (DUV) devices. [ABSTRACT FROM AUTHOR]

The strain relaxation, surface morphology, and reflectivity of AlGaN‐distributed Bragg reflectors (DBRs) grown via metal–organic chemical vapor deposition on AlN/Al2O3 templates are investigated. Strain relaxation begins in a 10‐period Al0.50Ga0.50N (27 nm)/Al0.75Ga0.25N (29 nm) DBR, and the degree of strain relaxation (DSR) increases with the number of DBR periods. The 30‐period DBR exhibits a peak reflectivity of 0.82 at 279 nm, with a stopband of 12 nm. The DSR of n‐Al0.62Ga0.38N on the 30‐period DBR increases from 70% to 100% as the n‐Al0.62Ga0.38N thickness increases from 0.4 to 2.5 μm. Although the surface of a DBR comprises numerous spiral hillocks, n‐Al0.62Ga0.38N grown on an AlGaN DBR exhibits a step‐flow growth. A DSR of 100% with threading screw dislocations of 2.0 × 108 cm−2 and threading edge dislocations of 1.2 × 109 cm−2 is obtained for a 2.5 μm‐thick n‐Al0.62Ga0.38N on a 30‐period AlGaN DBR. [ABSTRACT FROM AUTHOR]

The development of chitosan-coated nanoliposomes has emerged as a promising strategy for enhancing the intranasal delivery of therapeutic agents targeting the central nervous system. In this study, optimized Levetiracetam-loaded nanoliposomes (Opt-LEV-NLs) were coated with 0.1% and 0.3% chitosan to improve nasal uptake and mucoadhesion. The formulations were evaluated for vesicle size, entrapment efficiency, invitro release, surface morphology, zeta potential, and pH to select the best formulation for brain targeting. Results demonstrated that 0.1% chitosan-coated nanoliposomes (Chit-NLs) retained an optimal particle size (151.72 ± 1.37 nm), suitable for nasal delivery, with a satisfactory entrapment efficiency (64.56 ± 1.03%) and effective drug release (82.51 ± 2.15%). In contrast, 0.3% Chit-NLs exhibited larger particle sizes (> 300 nm), lower release rates, and reduced suitability for intranasal delivery. TEM and zeta potential analyses confirmed the successful chitosan coating and improved mucoadhesive properties. Based on these findings, 0.1% Chit-NLs were selected as the optimized formulation for further studies. This research supports the potential of chitosan-coated nanoliposomes for enhancing the bioavailability of Levetiracetam via the intranasal route. [ABSTRACT FROM AUTHOR]

Electrospun polystyrene (PS) fibers are produced using a mixed solvent of chloroform and n,n‐dimethylformamide (DMF) to investigate the influence of the solvent ratio on the fiber surface morphology and contact angle of the obtained mats. Electrospinning is a simple processing technique for producing fibers with diameters in the range of nanometers to a few micrometers. When using the different solvent ratios for this process, porous PS membranes are created due to nonsolvent and thermally induced phase separation (N‐TIPS). The morphology of the fibers is analyzed through scanning electron microscopy (SEM), which showed that fibers have diameters between 200 nm and 6 µm. SEM also revealed that the pores present on the surface of the fibers vary from densely compacted and well‐formed nanopores with diameters in the range of 20–50 nm to larger pores with sizes of ≈100–200 nm. The pore size varied with different solvent ratios. The surface area is analyzed using the Brunauer–Emmett–Teller (BET) method and found that the polymeric fibers have a high surface area (≈35 m2 g−1). The fibers with such morphology are highly hydrophobic, with a contact angle higher than 143°. These materials are excellent candidates for applications in textiles, filtration, and biomedical fields. [ABSTRACT FROM AUTHOR]

Due to its high durability and transparency, soda lime glass holds a huge potential for several applications such as photovoltaics, optical instrumentation and biomedical devices, among others. The different technologies request specific properties, which can be enhanced through the modification of the surface morphology with a nanopattern. Here, we report a simple method to nanostructure a glass surface with soft lithography and wet-chemical etching in potassium hydroxide (KOH) solutions. Glass samples etched with a polymeric mask showed a nanopattern with stripes of widths between 220 and 450 nm and modulated heights between 50 and 200 nm. For different solution concentrations or etching times, the obtained nanopatterns led to an increase or reduction of the water contact angle. The largest increment, ~20 degrees, was achieved by etching the glass for 180 min with 30% KOH concentration, while a super-hydrophilic glass (~9° contact angle) was achieved when etching for 90 min with the same concentration. Optical characterization showed a very low influence of the nanostructured pattern on glass transparency and an increment in UV transmittance for some cases. [ABSTRACT FROM AUTHOR]

In this article, the advantages of AlN low‐temperature interface protective layer (LT‐IPL) prepared by sputtering epitaxy for the fabrication of AlN/Al0.5Ga0.5N/AlN multichannel device structures are discussed. In this study, it is found that the use of LT‐IPL enhances the AlN/AlGaN interface surface morphology and reduces AlN/Al0.5Ga0.5N/AlN multichannel structure misfit dislocations. This approach results in a coherent four‐channel AlN/AlGaN/AlN structure with considerably improved crystallinity. Moreover, consistent with predictions from 1D simulations, reductions in sheet resistance are inversely proportional to the number of channels. These advancements are pivotal for the development of sophisticated AlN/AlGaN/AlN multichannel structures, which are tailored for applications that require low resistance and high voltage. [ABSTRACT FROM AUTHOR]

This study investigated the closed-loop recycling of 3D-printed wood fiber (WF)-filled polylactic acid (PLA) composites via fused filament fabrication (FFF). The WF–PLA composites (WPCs) were extruded into WPC filaments (WPCfs) to produce FFF-printed WPC parts (WPCps). The printed WPCps were reprocessed three times via extrusion and 3D-printing processes. The tensile properties and impact strengths of the WPCfs and WPCps were determined. To further investigate the impact of closed-loop recycling on the surface morphology, crystallinity, and molecular weight of WPCfs, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC), respectively, were used. After closed-loop recycling, the surface morphology of the WPCfs became smoother, and a decrease in the pore sizes was observed; however, the tensile properties (tensile strength and elongation at break) deteriorated. With increasing numbers of recycling iterations, the molecular weight of the PLA matrix decreased, while an increase in crystallinity was observed due to the recrystallization of the low-molecular-weight PLA molecules after recycling. According to the SEM images of the recycled WPCps, their layer heights were inconsistent, and the layers were rough and discontinuous. Additionally, the color difference (ΔE*) of the recycled WPCps significantly increased. Compared with those of the WPCps after recycling them only once, the tensile strength, elongation at break, and impact strength of the WPCps noticeably decreased after recycling them twice. Considering the changes in various properties of the WPCfs and WPCps, the FFF-printed WPC parts can be reprocessed only once through 3D printing. [ABSTRACT FROM AUTHOR]

The isothermal oxidation behavior of the Cu‐11.35Al‐3.2Ni‐3.5Mn (wt.%) shape‐memory alloy (SMA) in the temperature range of 500–900°C in oxygen was studied using the thermogravimetric (TG) method. TG curve showed that the alloy has parabolic isothermal oxidation characteristics. The effect of oxidation on the surface morphology and chemical composition of the Cu–Al–Ni–Mn alloy was determined by scanning electron microscopy, energy‐dispersive spectroscopy, and X‐ray photoelectron spectroscopy (XPS) analyses. The oxidation rate of SMA increases up to 700°C, remains stable at 800°C, and increases again up to 900°C. The XPS analysis identified that the corrosion products mainly contained MnO2, MnO/Mn2O3, and Al2O3. [ABSTRACT FROM AUTHOR]

To enhance the water solubility and bioavailability of astaxanthin esters, inclusion complexes of Z‐isomer‐enriched astaxanthin esters with water‐soluble carriers were prepared using a spray drying technique. A food‐grade Haematococcus alga extract was used as the source of astaxanthin esters, and the Z‐isomerization was performed via direct heating of the extract. Polyvinylpyrrolidone (PVP) and hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) were used as water‐soluble carriers. The effects of spray drying conditions on the encapsulation efficiency of astaxanthin esters in the carriers and the total Z‐isomer ratio of encapsulated astaxanthin esters were investigated, and the physical properties and storage stability of the resulting composites were evaluated. Under optimum spray drying conditions, efficient production of highly water‐soluble Z‐isomer‐rich astaxanthin esters was achieved in both carriers: >95% encapsulation efficiency and >55% total Z‐isomer ratio. The physical properties, such as surface morphology and particle size distributions, of the resulting particles differed significantly between PVP and HP‐β‐CD. Storage tests demonstrated that the formulated Z‐isomer‐rich astaxanthin esters were highly stable. Our findings will contribute to the practical applications of Z‐isomer‐rich astaxanthin materials. Practical Applications: The formulation technology developed in this study has the potential to address the industrial challenges of using astaxanthin, that is, low water solubility and low bioavailability. Furthermore, the low storage stability of astaxanthin Z‐isomers, which hinders their industrial use, can be solved simultaneously. The resulting Z‐isomer‐rich astaxanthin powders are expected to be used in a wide range of applications, including nutraceuticals, cosmetics, and animal feeds. [ABSTRACT FROM AUTHOR]

This study investigates groove-based controlled shape morphing in potatoes and carrots during drying. Stamps were manufactured and used to create groove depths (2 mm and 4 mm) onto the surface of the samples, which were then dried at various temperatures (45 °C, 55 °C, and 65 °C). Bending transformation, drying profiles, shrinkage, porosity, and surface morphology were measured as indicators of shape morphing. Potatoes exhibited a positive correlation between morphing transformation with increasing temperatures, reaching maximum angles of 244° (2 mm) and 263° (4 mm). Similarly, carrots showed similar observations with maximum bending angles of 145.1° (2 mm) and 153° (4 mm). The morphing in these samples was observed within the moisture content range of 1–0.5 kg water per kg solids and was concomitant with a substantial shrinkage of 80–84% in both samples. Grooving significantly affects the morphing, creating high-stress points and increasing the moisture transfer rate during drying. This study lays foundational knowledge for the controlled shape morphing of foods using drying technology. [ABSTRACT FROM AUTHOR]

The current work aims to develop a bigel-containing clobetasol propionate-loaded PLGA microparticles and further assess its in vitro, ex vivo, and in vivo behavior for psoriasis management. PLGA microparticles (2%w/w) containing clobetasol propionate were developed by solvent evaporation technique. For the developed particles, size, drug loading, entrapment efficiency, and surface morphology were determined. Further, the particles were suspended into bigel developed from oleogel and hydrogel (40:60) and assessed for stability, in vitro drug release, ex vivo skin permeation, retention, and in vivo study in BALB c mice for antipsoriatic potential. PLGA microparticles developed by solvent evaporation were found to have a mean particle size of 19.45 ± 1.74 μm. Drug loading and entrapment efficiency for clobetasol were found to be 43.5 ± 4.94% and 94.5 ± 3.68%, respectively. For the developed bigel, sustained in vitro drug release was observed till 7 h. Ex vivo skin permeation with the developed formulation was found to be higher than the marketed formulation and drug suspended in bigel. A retention study performed on pig skin suggested the topical skin retention of the drug. Further, the psoriatic model was developed in BALB c mice with IMQ cream, and it was observed that the developed formulation helped considerably reduce the irritation score and PASI scoring in mice as compared to the standard treatment. The same is corroborated with the help of histopathological studies performed by Hematoxylin and Eosin (H&E) staining in the same animals. The study findings suggest that clobetasol microparticle-loaded bigel formulation appeared to be a promising therapy option for psoriasis. [ABSTRACT FROM AUTHOR]

To study the effects of long-range temporal correlations on kinetic roughening of the molecular beam epitaxy (MBE) growth systems in both (1 + 1) - and (2 + 1) -dimensions, we adopt fast fractional Gaussian noise (FFGN) technique to generate temporally correlated noise to the continuum growth equations including Mullins–Herring (MH) and Villain–Lai–Das Sarma (VLDS), and the typical discrete growth models including Das Sarma–Tamborenea (DT) and Wolf–Villain (WV) with slight modifications. Extensive numerical simulations on these continuum and discrete growth systems are performed in the presence of long-range temporal correlations, and the scaling exponents are obtained correspondingly. We find that these correlated growth systems exhibit high dependence on the temporal correlation exponent within the large temporal correlated regimes, and there exist non-trivial scaling properties in the correlated DT and WV models. Our results also show that the scaling exponents in these linear and nonlinear MBE growth equations are in good agreement with the theoretical predictions. Furthermore, the saturated surface morphologies are compared qualitatively through simulating numerically these continuum and discrete growth systems in the presence of long-range temporal correlations. Generally, as the temporal correlation exponent increases, the surface heights of these correlated discrete and continuum growth systems exhibit evident increasing trends. Likewise, with the temporal correlation exponent increasing, the surface morphologies of the modified DT and WV models undergo a gradual transition from self-affine hills to sharp peaks, while the growing surfaces of the correlated MH and VLDS equations gradually become relatively smooth. [ABSTRACT FROM AUTHOR]

This article aims to evaluate and compare two types of organic surface-modified-nanoclay of octadecylamine-modified-bentonite-nanoclay (ODA-BNC) and aminopropyltrimethoxysilane-octadecylamine-modified-nanomontmorillonite (APS-ODA-MMT). Each type of nanoclay is combined with silica as a bi-filler for natural rubber (NR)/ethylene propylene diene monomer rubber (EPDM) in a 50/50 blend ratio for possible vulcanized rubber nanocomposite application. The total filler content is 50 phr while nanoclay filler content ranges from 0 to 20 phr, keeping the other ingredients ratio fixed. The prepared composites are characterized by the Fourier transform infrared spectrophotometer (FTIR) and their mechanical and thermal properties are thoroughly investigated. The data reveal that the fillers added to the rubber can improve its surface properties according to their type and amount as confirmed by the Atomic force microscope (AFM), and Scanning electron microscope (SEM) investigation. The surface of rubber containing APS-ODA-MMT displayed higher height (251) and roughness surface (94.11), than those (69.8) and (45.62) respectively, containing ODA-BNC. Moreover, the acid resistance of the prepared composites is verified and indicated that increasing the nanoclay ratio (20%) enhances the acid resistance by reducing the surface distortion while keeping the surface morphology. The mechanical properties and Thermogravimetric Analysis (TGA) measurements showed that the rubber containing ODA-BNC has higher values of stress (2.2), elongation (975), and thermal stability (470, 505, 520°C) than those (1.75), (650), and (440, 460, 470°C) respectively, containing the APS-ODA-MMT. Moreover, the durability investigation of the vulcanized rubber via the AFM found the modified composites can be used in harsh environments as a covering layer in petrochemical networks or chemical factories. [ABSTRACT FROM AUTHOR]

The current study aimed to evaluate the pharmacokinetics and neuroprotective effect of well-characterised berberine-bovine serum albumin (BBR-BSA) nanoparticles. BBR-BSA nanoparticles were generated by desolvation method. Entrapment efficiency, loading capacity, particle size, polydispersity index, surface morphology, thermal stability, and in-vitro release were estimated. In-vitro pharmacokinetic and tissue distribution were conducted. Their neuroprotection was evaluated against lipopolysaccharides-induced neurodegeneration. BBR-BSA nanoparticles showed satisfactory particle size (202.60 ± 1.20 nm) and entrapment efficiency (57.00 ± 1.56%). Results confirmed the formation of spheroid-thermal stable nanoparticles with a sustained drug release over 48 h. Sublingual and intranasal routes had higher pharmacokinetic plasma profiles than other routes, with Cmax values at 0.75 h (444 ± 77.79 and 259 ± 42.41 ng/mL, respectively). BBR and its metabolite distribution in the liver and kidney were higher than in plasma. Intranasal and sublingual treatment improves antioxidants, proinflammatory, amyloidogenic biomarkers, and brain architecture, protecting the brain. In conclusion, neuroinflammation and neurodegeneration may be prevented by intranasal and sublingual BBR-BSA nanoparticles. [ABSTRACT FROM AUTHOR]

Electrochemical nanoimprinting (ECNI) is a microstructure fabrication technique that combines metal-assisted chemical etching (MaCE) with nanoimprint lithography. A significant advantage of ECNI over traditional MaCE is the reusability of the stamp and excellent pattern consistency. This work studies the effects of various etchant components on etching results, discussing the associative parameters separately. Experimental results demonstrate that ECNI successfully fabricates bi-layer microstructures with flat surface morphology, where the second layer has a feature size of 40 μ m and a depth of 12.5 μ m. These findings highlight ECNI's potential as a scalable method for producing complex multi-layer structures, positioning it as a promising solution for large-scale microfabrication of semiconductors. [ABSTRACT FROM AUTHOR]

In this paper, the effects of ultrasonic vibration and powder mixed on Electrical Discharge Machining (EDM) are investigated. Based on the heat transfer theory, an ultrasonic powder mixed EDM (US-PMEDM) heat transfer model combining ultrasonic vibration and powder mixed characteristics is established, and the heat transfer model carries out a transient thermodynamic simulation for the process of removing the material during the EDM process, and through the experimental and simulation analysis of four kinds of EDM, powder mixed EDM (PMEDM), ultrasonic (UEDM), and US-PMEDM, the accuracy of the simulation is verified. The accuracy of the simulation was verified by observing the surface morphology after machining. The material removal process was analyzed under different machining methods and different concentrations of powder mixed particles. Under the processing conditions of fixed processing current of 2A, ultrasonic amplitude of 5 µm, and powder concentration of 2g/L, the material removal rate (MRR) of the PMEDM method was increased by about 26.3% and the surface roughness (SR) was reduced by 7.78% compared with that of the EDM method, and the material removal rate of the US-PMEDM method was increased by about 49.4% and the surface roughness was increased by 4.05% compared with that of the EDM method. The surface quality can be improved by adding powder mixing, and the surface quality of powder mixing is better than that of ultrasonic vibration. [ABSTRACT FROM AUTHOR]

In this study, multifunction cavitation (MFC) was performed on low‐alloy steel (AISI 4140 steel) rods with different hardnesses to increase their fatigue limit. It was found that a high compressive residual stress was generated on the surface of steel rods by MFC and that the magnitude of the compressive residual stress tended to increase with increasing specimen hardness, which resulted in a higher fatigue limit. However, fatigue cracks are known to be initiated from the pits and red rust that form on the surface during MFC treatment in water. Furthermore, relaxation of the compressive residual stress was also investigated during the fatigue test to elucidate the mechanism for improving the fatigue properties. The results showed that the fatigue limit for MFC‐treated steel rods was accurately estimated by considering residual stress relaxation, hardness, and pit formation. Validation of the fatigue limit estimation was also conducted through comparison with Murakami's equation. Highlights: MFC generated compressive residual stress on the surface of steel rods.MFC increased the fatigue limit for steel rods.The fatigue limit of MFC‐treated steel rods with different hardnesses was estimated.Fatigue cracks were initiated at surface pits formed by MFC. [ABSTRACT FROM AUTHOR]

The structural and luminescence properties of the Lu 3 Al 4 Sc 1 O 12 :Pr and Gd 3 Al 3 Sc 2 O 12 :Pr garnet scintillators co-doped with boron (B3+) ions were investigated. The addition of B3+ and Sc3+ to the structure has a positive effect on the luminescence properties, especially on the photo, radio emission intensities, quantum efficiency, and results in a reduction of the decay time, which is necessary for high-quality scintillators. Structural properties of garnets have been determined after X-ray diffraction analysis coupled with Rietveld refinement. Surface morphology analysis was performed using a scanning electron microscope and particle size was also determined. Elemental composition was confirmed by the ICP-OES technique. Reflection, excitation (in the UV and VUV range), emission (upon excitation by UV or X-rays), decay time, and quantum efficiency at room temperature were measured. Furthermore, the influence of temperature on excitation, emission, and decay curves was also analyzed. The obtained luminescence properties indicated positive effect caused by doping. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, chitin was extracted using a single step of deproteinization from the whole locust and its different morphological parts (thorax, legs, abdomen, head and wings). All chitins present an α structure with contents of 10 to 12% and high degrees of acetylation (DA) (92–96%). Physicochemical differences are observed among the chitins from the different parts, particularly in terms of crystallinity indexes (54–72%), molar masses Mv (537,000–672,000 g·mol−1) and surface morphology (fibrous or porous). The N-deacetylation of chitins from the different parts was carried out using KOH in an anhydrous medium (Broussignac process). Other tests using NaOH in an aqueous solution (Kurita process) were also applied to the chitin from the legs. The results show that it is possible to valorize the desert locust by preparing highly deacetylated chitosan (4–14%) with remarkably low to relatively high Mv (11,000–123,000 g·mol−1), depending on the process used. [ABSTRACT FROM AUTHOR]

Elastomeric products in service condition undergoe thermo-oxidative degradation under the influence of temperature, oxygen, ozone etc. Tyre is one such product where ageing phenomena affect its performance properties as it is subjected to various temperature and environmental conditions during its service life. However, ageing is a complex process and depends on many factors that include rubber type, temperature, stress level, etc. To study the underlying mechanism and kinetics of such intriguing phenomenon, a Natural Rubber based compound was chosen in the present work. The rubber compound was subjected to an aerobic ageing at a fixed temperature of 70 °C and the effect of prolonged ageing time (1 week, 2 weeks, 4 weeks, and 8 weeks) on key performance properties such as, mechanical, dynamic mechanical and fatigue crack growth resistance was evaluated. Fatigue crack growth (FCG) studies were conducted to understand the degradation of crack growth resistance with respect to ageing. The morphology of the fractured surface was also captured by Field Emission Scanning Electron Microscope to reveal the nature of fracture failure. The static as well as dynamic modulus of aged compound was found to be significantly increased with increase in ageing time which was an indication of enhanced cross-linking density. This enhanced stiffness leads to deterioration of the fatigue resistance property and as a result FCG rate increased with ageing time. The samples were characterized by Fourier transform infrared spectroscopy to understand the changes in chemical structure during ageing which revealed that intensity of double bond content was reduced by increasing ageing time. Apparent cross-linking density and other relevant chemical analysis were also performed to establish the proposed mechanism. [ABSTRACT FROM AUTHOR]

The fatigue performance of emulsified asphalt mastics directly affects the long-term service performance of emulsified asphalt cold recycled pavement. Fatigue properties of 24 different mastics before and after short-term aging composed by the combination of 3 different fillers and 4 filler-binder ratios (F-B) were evaluated based on the viscoelastic continuum damage (VECD) model. Atomic force microscopy (AFM) was employed to analyze the surface morphology of the mastics and determine the interaction between filler and asphalt. The results show that increasing the F-B or the aging effect reduce the stress–strain withstand capacity of emulsified asphalt mastic, increase its integrity damage rate, and further reduce the fatigue life. Comparing three mastics, limestone mastic with a low F-B exhibits a better fatigue performance. The limestone mastic is more affected by short-term aging, while cement mastic and coal gangue mastic are significantly affected by F-B. Filler types, F-B and aging can obviously change the surface morphology of mastics. The microscopic morphology change of coal gangue mastic with a low F-B is dominated by the dispersing effect of the filler, whereas the microscopic morphology of mastic with a high F-B is dominated by the adsorption effect. [ABSTRACT FROM AUTHOR]

Thin films of (Y0.06Ga0.94)2O3:Cr were obtained by radio-frequency (RF) ion-plasma sputtering in an argon atmosphere on polycrystalline polycor and amorphous υ-SiO2 substrates. The surface morphology of the films was studied by atomic force microscopy. It was found that during argon annealing of (Y0.06Ga0.94)2O3:Cr thin films on υ-SiO2 substrates, grain growth occurs perpendicular to the substrate surface. The results of studies of the photoluminescence and cathodoluminescence luminescence of the investigated films are presented. It is shown that thin films of (Y0.06Ga0.94)2O3:Cr on υ-SiO2 substrates under photoexcitation emit in the blue region of the spectrum and this luminescence is due to the luminescence of the (Y0.06Ga0.94)2O3 matrix. Under cathodic excitation, the activator luminescence of the Cr3+ ion dominates with a maximum in the region around 700 nm, due to the electronic transitions 4T2 → 4A2. [ABSTRACT FROM AUTHOR]

This study examines the interface of biodegradable polylactic acid (PLA) fiber-reinforced thermoplastic starch composites to address market demand for their mechanical properties. We first used a combination of solution treatment (acid/alkali) and plasma modification to modify fibers. This method improves surface roughness and increases oxygen-containing groups of the fibers, which enhances the mechanical interlocking at the interface and promotes stronger hydrogen bonds between fibers and starch, respectively. Their synergy effect significantly strengthens interfacial adhesion and interfacial shear strength (IFSS). In contrast, cold plasma modification alone results in a smaller increase in IFSS because of its lower roughness and fewer oxygen-containing groups. Alkaline treatment and increased cold plasma power level are more conducive to higher IFSS through stronger synergistic effects. Although IFSS improved from 2.41 to 4.40 MPa after alkali and plasma treatments of 200 W, the tensile strength decreased from 811.46 to 351.55 MPa. To optimize the mechanical properties of composite materials, it is crucial to choose a kind of modification method that balances IFSS enhancement and tensile strength reduction. [ABSTRACT FROM AUTHOR]

The porous TC4 titanium alloy prepared by selective laser melting (SLM) is modified by micro‐arc oxidation (MAO) technology. By introducing active elements such as calcium (Ca) and phosphorus (P) into the electrolyte, a wear‐resistant active coating is constructed on the surface of porous TC4. The effects of MAO process parameters on the surface morphology and wear resistance of the coating are discussed. The results show that the thickness and adhesion of the coating increase with the increase of the first‐stage oxidation time, and decrease with the increase of the second‐stage oxidation time. In all processes, the MAO‐2 coating has better surface morphology and performance, with a median pore size of 0.51 μm and a binding force of 18 N. XPS analysis confirms that the coating is mainly composed of TiO2, Ca2P2O7, and Ca(PO3)2 phases. The study of tribological behavior shows that the wear form of the substrate is abrasive wear, while the wear form of the coating is adhesive wear. The friction coefficient of the coating is significantly lower than that of the substrate, and the wear resistance is better. This study provides an effective way to optimize the surface properties of porous TC4 titanium alloy. [ABSTRACT FROM AUTHOR]