Search Results (131)

Nanostructured metallic materials are widely applied in various fields due to their excellent comprehensive properties. Enhancing mechanical properties through microstructure design has emerged as a novel strengthening strategy. In this contribution, the microscopic mechanical behavior of coarse-grained and gradient-structured nanocrystalline NiCoAl alloys during tensile deformation was investigated via molecular dynamics simulations. Based on the investigation of compositional effects, the Ni₆₀Co₃₀Al₁₀ alloy composition was selected, exhibiting a yield strength of 4.92 GPa. The results indicate that increasing Al content reduces the material’s strength, Young’s modulus, and work hardening effect. Furthermore, by introducing a gradient structure with grain sizes gradually varying from 1.8 nm to 6.5 nm into the alloy, the yield strength reaches 1.8 GPa and the flow stress reaches 3.35 GPa, demonstrating a significant improvement compared to the uniform coarse-grained structure. Upon introducing the gradient structure into the alloy, it was observed that geometrically necessary dislocations (GNDs) nucleate in the coarse-grained region during deformation and gradually extend towards the fine-grained region. The increased grain boundary density effectively impedes dislocation motion and enhances dislocation pinning capability, thereby inducing continuous strain hardening and improving plasticity. By promoting the accumulation and interaction of grain boundary dislocations, the gradient structure achieves further strengthening and strain hardening in the alloy, providing a theoretical basis and simulation foundation for designing high-performance advanced alloys. Full article

This study investigates the synergistic effects of an electropulsing (EP) and ultrasonic impact treatment (UIT) hybrid process on the mechanical and corrosion properties of D36 low-carbon steel. Conventional UIT has been shown to enhance surface hardness and induce compressive residual stress but is limited by a shallow affected depth and potential for increased surface roughness, which can exacerbate corrosion. In this work, we integrate high-energy electropulsing with UIT to overcome these limitations. The EP-UIT process leverages the combined effects of acoustoplasticity, thermal softening, and electroplasticity to achieve a significantly deeper hardened layer, extending beyond 2 mm, which is an order of magnitude thicker than that obtained by UIT alone. Microstructural analysis reveals that the process induces continuous dynamic recrystallization (CDRX), resulting in a gradient nanostructured layer with equiaxed grains near the surface and submicron ferrite grains at greater depths. Additionally, cementite dissolution and reprecipitation lead to a dual-phase microstructure comprising a supersaturated ferrite matrix and spheroidized Fe₃C particles. The EP-UIT treatment also forms a dense oxide scale composed primarily of magnetite (Fe₃O₄) and hematite (α-Fe₂O₃), significantly enhancing corrosion resistance. Potentiodynamic polarization tests demonstrate that EP-UIT reduces the corrosion current density by 68% compared to UIT-treated samples, while electrochemical impedance spectroscopy confirms the improved barrier properties of the oxide layer. This innovative approach offers a promising strategy for significantly extending the service life of welded marine structures by concurrently enhancing their mechanical properties and corrosion resistance. Full article

In high-precision optical systems such as laser optics, astronomical observation, and semiconductor lithography, anti-reflection coatings are crucial for light transmittance, imaging quality, and stability, but traditional designs face modeling challenges in balancing ultralow reflectivity, high wavefront quality, and manufacturability amid multi-dimensional parameter coupling and multi-objective constraints. This study addresses these by proposing a unified mathematical modeling framework integrating a Symmetric five-layer high-low refractive index alternating structure (V-H-V-H-V) with dual-scale nanostructures, employing a constrained quasi-Newton optimization algorithm (L-BFGS-B) to minimize reflectivity, wavefront root-mean-square (RMS) error, and surface roughness root-mean-square (RMS) in a six-dimensional parameter space. The Sellmeier equation is adopted to calculate wavelength-dependent material refractive indices, the model uses the transfer matrix method for the Symmetric five-layer high-low refractive index alternating structure’s reflectivity, incorporates nano-surface height function gradient correction, sub-wavelength modulation, and radial optimization, applies Zernike polynomials for low-order aberration correction, quantifies surface roughness via curvature proxies, and optimizes via a weighted objective function prioritizing low reflectivity. Numerical results show the spatial average reflectivity at 632.8 nm reduced to 0.13%, the weighted average reflectivity across five representative wavelengths in the 550–720 nm range to 0.037%, the reflectivity uniformity to 10.7%, the post-correction wavefront RMS to 11.6 milliwavelengths, and the surface height standard deviation to 7.7 nm. This framework enhances design accuracy and efficiency, suits UV nanoimprinting and electron beam evaporation, and offers significant value for high-power lasers, lithography, and space-borne radars. Full article

The miniaturisation of electronic devices has intensified the demand for compact, high-performance lithium-ion batteries. This review synthesises recent progress in microscale battery development, focusing on microfabrication techniques, nanostructured materials, porosity-engineered architectures, and strategies for reducing non-active components. It explores both top–down and bottom–up fabrication methods, the integration of nanomaterials, the role of gradient electrode architectures in enhancing ion transport and energy density, along with strategies to reduce non-active components, such as separators and current collectors, to maximise volumetric efficiency. Advances in top–down and bottom–up fabrication methods, including photolithography, laser structuring, screen printing, spray coating, mechanical structuring, and 3D printing, enable precise control over electrode geometry and enhance ion transport and material utilisation. Nanostructured anodes, cathodes, electrolytes, and separators further improve conductivity, mechanical stability, and cycling performance. Gradient porosity designs optimise ion distribution in thick electrodes, while innovations in ultra-thin separators and lightweight current collectors support higher energy density. Remaining challenges relate to scalability, mechanical robustness, and long-term stability, especially in fully integrated micro-battery architectures. Future development will rely on hybrid fabrication methods, advanced material compatibility, and data-driven optimisation to bridge laboratory innovations with practical applications. By integrating microfabrication and nanoscale engineering, next-generation LIBs can deliver high energy density and long operational lifetimes for miniaturised and flexible electronic systems. Full article

The phase transitions and switching dynamics of topological polar textures in hafnium oxide (HfO₂)-based cylindrical-shell ferroelectrics are studied using a three-dimensional (3D) phase field model based on the self-consistent solution of the time-dependent Ginzburg–Landau model and Poisson equation. The comprehensive interplays of bulk free energy, gradient energy, depolarization energy, and elastic energy are taken into account. When a cylindrical ferroelectric device is biased under the in-plane radial electric field, there is a size-controlled phase transition between the ferroelectric (FE), antiferroelectric (AFE), and paraelectric (PE) phases, depending on ferroelectric film thickness and cylindrical shell radius. For in-plane polarization textures at the equilibriums, the FE phase has a Néel-like texture with a center-type four-quad domain, the AFE phase has a monodomain texture, and the PE phase has a Bloch-like texture with a vortex four-quad domain. These polarization domain textures are resultant from energy competition and topologically protected by the geometrical confinement. The polarization dynamics from polar states towards equilibriums are analyzed considering the separated contributions of x- and y-components of polarizations that are driven by x-y in-plane electric fields. The emergent topological domains and phase transitions provide guidelines for geometrical engineering of a novel nano-structured ferroelectric device that is different from the planar one, offering new possibilities for multi-functional high-density ferroelectric memory. Full article

Multifunctional nanomaterials have been extensively investigated in theranostics to enhance therapeutic specificity, biocompatibility, and responsiveness to external magnetic gradients. We synthesized magnetoplasmonic nanocomposites comprising magnetite nanoparticles modified with gold and silver. Magnetite was synthesized via chemical co-precipitation and stabilized in an aqueous medium using glucose, which also served as a reducing agent for Au³⁺ and Ag⁺ ions on the nanoparticle surface. Microstructural, magnetic, spectral, and optical characterizations confirmed the successful formation of nanocomposites with properties suitable for biomedical applications. Plasmonic behavior was evidenced by visible-range absorbance maxima at 398 nm (Ag) and 538 nm (Au), while Transmission Electron Microscopy (TEM) revealed mean diameters of 21 and 23 nm. Zeta potential values of +23 mV for magnetite–silver and −40 mV for magnetite–gold nanocomposite samples indicated good suspension stability. Antibacterial activity against Gram-positive and Gram-negative bacteria was evaluated using agar diffusion and by determining the minimum inhibitory (MIC) and bactericidal (MBC) concentrations. Silver-modified magnetite nanocomposites exhibited the most potent effects, with MIC values of 0.01 mg/mL for Escherichia coli (E. coli) and 0.02 mg/mL for Staphylococcus aureus (S. aureus), and corresponding MBC values of 0.027 mg/mL and 0.055 mg/mL, respectively. These magnetoplasmonic nanostructures have significant potential for overcoming antibiotic resistance and enabling targeted therapeutic action through magnetic guidance. Full article

This review examines scientific and engineering strategies for adapting bituminous and asphalt concrete materials to the highly diverse climates of Central Asia. The region’s sharp gradients—from arid lowlands to cold mountainous zones—expose pavements to thermal fatigue, photo-oxidative aging, freeze–thaw cycles, and wind abrasion. Existing climatic classifications and principles for designing thermally and radiatively resilient pavements are summarized. Special emphasis is placed on linking binder morphology, rheology, and climate-induced transformations in composite bituminous systems. Advanced characterization methods—including dynamic shear rheometry (DSR), multiple stress creep recovery (MSCR), bending beam rheometry (BBR), and linear amplitude sweep (LAS), supported by FTIR, SEM, and AFM—enable quantitative correlations between phase composition, oxidative chemistry, and mechanical performance. The influence of polymeric, nanostructured, and biopolymeric modifiers on stability and durability is critically assessed. The review promotes region-specific material design and the use of integrated accelerated aging protocols (RTFOT, PAV, UV, freeze–thaw) that replicate local climatic stresses. A climatic rheological profile is proposed as a unified framework combining climate mapping with microstructural and rheological data to guide the development of sustainable and durable pavements for Central Asia. Key rheological indicators—complex modulus (G*), non-recoverable creep compliance (Jnr), and the BBR m-value—are incorporated into this profile. Full article

In the present paper, the fatigue performance of a TC6 titanium alloy with a microstructure gradient and residual stress gradient produced by laser shock peening (LSP) is investigated. After LSP, a 1 mm thickness gradient compressive residual stress layer with a maximum surface compressive residual stress of −708 MPa is introduced into the materials. Electron back-scattering diffraction (EBSD) and transmission electron microscopy (TEM) techniques are used to characterize the microstructural evolution of the TC6 titanium alloy subjected to LSP. The results show that a nanostructured layer forms on the surface of the TC6 titanium alloy. At a depth of 20 μm, high dense dislocation and nanocrystalline are observed on the top surface. Based on the results of the microstructural characterization, it is found that dislocation movement is the main reason for the formation of nanocrystalline on the top surface. A high-cycle fatigue test showed that the fatigue limit of the TC6 titanium alloy treated by LSP improves from 431 ± 10 MPa to 486 ± 14 MPa, increasing by 12.8%. Full article

This paper delves into the impact of Y doping on In₂O₃ thermoelectric materials. Yttrium doping significantly modifies the properties of In₂O₃, with far-reaching implications for its thermoelectric performance and mechanical characteristics. In the electrical domain, Y³⁺ substitution for In³⁺ optimizes carrier concentration and mobility. The alteration of the electronic band structure leads to a balanced improvement in the Seebeck coefficient and electrical conductivity, boosting the power factor. Despite initial lattice distortion-induced mobility changes, carrier screening at suitable doping levels counteracts this, enhancing overall electrical conductivity. Regarding thermal conductivity, multiple factors act synergistically. Lattice distortion, along with the generation of point defects, dislocations, nanostructuring, and modulated electron–phonon interactions, jointly reduce heat transfer. This reduction is vital for maintaining a substantial temperature gradient, a prerequisite for efficient thermoelectric conversion. The observed increase in ZT (the thermoelectric device figure of merit) with the highest value from ~0.055 to ~0.275. Full article

Fabrication of gradient nanostructure on metal surfaces is recognized as an effective approach for enhancing mechanical and surface properties, as well as serving as a pretreatment for subsequent surface engineering. Unfortunately, their fabrication on high-strength and low-ductility metal surface poses a significant challenge due to the prevalent issue of process-induced surface damage. In this study, we report the successful fabrication of a gradient nanostructured surface layer with low roughness (Ra ~ 0.17 μm) on high-strength 38CrMoAl steel through an optimized ultrasonic severe surface rolling (USSR) processing. By systematically varying the tempering temperature of quenched-and-tempered samples, the strength and ductility of the 38CoMoAl steel are tailored to facilitate gradient nanostructure formation. Microstructural analysis via advanced electron microscopy reveals the gradient nanostructure features progressively coarser martensite/ferrite grains and decreasing dislocation density along the depth. As the tempering temperature increases from 600 °C to 700 °C, the yield strength of 38CrMoAl steel decreases from 915 ± 16 MPa to 815 ± 16 MPa, while the elongation increases from 18.7 ± 0.6 to 27.3 ± 1.2%, resulting in an increase in the thickness of the gradient nanostructured surface layer from 300 μm to 400 μm. Following USSR processing, samples tempered at 600 °C, 650 °C, and 700 °C exhibit significant enhancements in surface hardness by 7.3%, 22.7%, and 21.5%, respectively, along with substantial reduction in wear volume by 73%, 78%, and 60%. USSR processing also leads to a reduction in coefficient of friction. This work provides valuable insights into the fabrication of high-quality gradient nanostructures on high-strength, low-ductility metallic materials. Full article

Microfluidics enables precise manipulation of scarce Traditional Chinese Medicine (TCM) samples while accelerating analysis and enhancing sensitivity. Device-level structures explain these gains: staggered herringbone and serpentine mixers overcome low-Reynolds-number constraints to shorten diffusion distances and reduce incubation time; flow-focusing or T-junction droplet generators create one-droplet–one-reaction compartments that suppress cross-talk and support high-throughput screening; “Christmas-tree” gradient generators deliver quantitative dosing landscapes for mechanism-aware assays; micropillar/weir arrays and nanostructured capture surfaces raise surface-to-volume ratios and probe density, improving capture efficiency and limits of detection; porous-membrane, perfused organ-on-a-chip architectures recreate apical–basolateral transport and physiological shear, enabling metabolism-aware pharmacology and predictive toxicology; wax-patterned paper microfluidics (µPADs) use capillary networks for instrument-free metering in field settings; and lab-on-a-disc radial channels/valves exploit centrifugal pumping for parallelised workflows. Framed by key performance indicators—sensitivity (LOD/LOQ), reliability/reproducibility, time-to-result, throughput, sample volume, and sustainability/cost—this review synthesises how such structures translate into value across TCM quality/safety control, toxicology, pharmacology, screening, and delivery. Emphasis on structure–function relationships clarifies where microfluidics most effectively closes gaps between chemical fingerprints and biological potency and indicates practical routes for standardisation and deployment. Full article

Fog water collection, as a sustainable approach to alleviating water scarcity, has attracted considerable attention due to its low energy consumption and environmental friendliness. Various organisms in nature have evolved unique biological structures that efficiently capture and direct fog water. The fog water collection structures (FWCSs) and physical mechanisms of these organisms provide valuable inspiration for innovations in fog water collection technologies. This review systematically summarizes biomimetic structures designed for fog water collection, with a focus on representative natural examples such as the Namib desert beetle, cactus spines, spider silk, and Nepenthes mirabilis, highlighting how they achieve efficient fog water capture, coalescence, and transport through special surface textures, wettability regulation, and structural design. The underlying physical mechanisms are discussed in depth, including droplet behavior on micro/nanostructured surfaces, surface energy gradients, and Laplace pressure gradients in directional droplet transport. On this basis, the current challenges in bioinspired FWCSs design are outlined, and future perspectives are proposed. Future research may focus on the multiscale structural optimization of bioinspired FWCSs, the development of dynamically tunable designs, and the use of efficient and sustainable materials to further enhance fog water collection efficiency and ensure the long-term stability of FWCSs. Ultimately, by integrating modern manufacturing technologies and stimuli-responsive materials, bioinspired FWCSs hold great potential for applications in extreme environments, agricultural irrigation, and energy-efficient architecture, offering innovative solutions to the global water crisis. Full article

Nanostructures, such as carbon nanotubes (CNTs), graphene, nanoplates, etc., show behaviors that classical continuum theories cannot capture. At the nanoscale, size effects, surface stresses, and nonlocal interactions become important, so new models are needed to study nanostructures. The main nanomechanics theories that are used in recently published papers include nonlocal elasticity theory (NET), couple stress theory (CST), and nonlocal strain gradient theories (NSGTs). To solve these models, methods such as finite elements, isogeometric analysis, mesh-free approaches, molecular dynamics (MD), etc., are used. Also, this review categorizes and summarizes the major theories and numerical methods used in nanomechanics for the analysis of nanostructures in recently published papers. Recently, machine learning methods have enabled faster and more accurate prediction of nanoscale behaviors, offering efficient alternatives to traditional methods. Studying these theories, numerical models and data driven approaches provide an important foundation for future research and the design of next generation nanomaterials and devices. Full article

This study systematically investigates the surface nanocrystallization of 35CrMo steel induced by Ultrasonic Surface Rolling Processing (USRP). It reveals the formation of a gradient nanostructure, where martensite lath fragmentation under high-frequency impacts leads to a surface layer of equiaxed nanocrystals and high-density dislocations. This novel microstructure yields exceptional surface integrity: roughness is minimized to 0.029 μm due to plastic flow, residual stress is transformed into high compressive stress, and surface microhardness is significantly enhanced by 32.3%, primarily governed by grain refinement and dislocation strengthening. Consequently, the treated material exhibits a 28.9% reduction in wear mass loss, which is directly attributed to the combined effects of the strengthened gradient layer’s improved load-bearing capacity and the effective suppression of crack initiation by compressive residual stresses. Our findings not only provide direct microstructural evidence for classic strengthening theories but also offer a practical guide for optimizing the surface performance of high-strength alloy components. Full article

This study introduces a novel numerical approach to analyze the axisymmetric bending behavior of functionally graded (FG) graphene platelet (GPL)-reinforced annular sandwich nanoplates featuring a porous core. The nanostructures are exposed to coupled magnetic and hygrothermal environments. The porosity distribution and GPL weight fraction are modeled as nonlinear functions through the thickness, capturing realistic gradation effects. The governing equations are derived using the virtual displacement principle, taking into account the Lorentz force and the interaction with an elastic foundation. To address the size-dependent behavior and thickness-stretching effects, the model employs the nonlocal strain gradient theory (NSGT) integrated with a modified version of Shimpi’s quasi-3D higher-order shear deformation theory (Q3HSDT). The differential quadrature method (DQM) is applied to obtain numerical solutions for the displacement and stress fields. A detailed parametric study is conducted to investigate the influence of various physical and geometric parameters, including the nonlocal parameter, strain gradient length scale, magnetic field strength, thermal effects, foundation stiffness, core thickness, and radius-to-thickness ratio. The findings support the development of smart, lightweight, and thermally adaptive nano-electromechanical systems (NEMS) and provide valuable insights into the mechanical performance of FG-GPL sandwich nanoplates. These findings have potential applications in transducers, nanosensors, and stealth technologies designed for ultrasound and radar detection. Full article