To meet the demand for high-efficiency and high-reliability spot joining in lightweight structures, a rapid welding mode involving only plunging and retracting stages was implemented based on the previously developed synergistic double-sided probeless friction stir spot welding (SDP-FSSW) process. Using 6061-T6 aluminum alloy as the base material, the effects of rotation speed on joint microstructure, mechanical performance, and fracture behavior were systematically investigated. The results show that, even without a dwelling stage, the rapid SDP-FSSW process achieves stable high-strength joints, with tensile/shear strengths exceeding 5 kN and reaching a maximum of 10,064.3 N at 600 rpm. During welding, the cooperative rotation of the two shoulders induces pronounced wavy hook structures on both sides of the interface, which effectively suppress crack propagation along the interface through the combined effects of mechanical interlocking and metallurgical bonding, thereby enabling short-cycle, high-strength joining. Fracture analysis indicates that the joint failure mode transitions from plug-pull fracture to shear fracture with increasing rotation speed, and high-strength joints exhibit abundant tensile dimples and pronounced plastic deformation, characteristic of typical ductile fracture behavior.

Heterogeneous alloy designs can significantly enhance the mechanical properties of metallic materials through synergistic effects. In this work, the cold spray additive manufacturing (CSAM)-assisted brazing is proposed to significantly improve the mechanical properties of Cf/C and superalloy joint. The CSAM process promotes the atomic diffusion and metallurgical reaction between the interlayer and superalloy substrate. The findings indicate that the diffusion of Fe, Cr, Ni and Ti within brazing seam promotes the formation of a novel dual-phase heterogeneous structure, comprising a Cr-rich σ phase and a Ni3Ti phase. The σ and Ni3Ti dual-phase heterogeneous structure significantly improves shear strength through a synergistic strengthening mechanism, achieving an effective combination of strength and toughness. The ductile Ni3Ti phase enhances the deformation capacity, while the hard σ phase serves as a continuous barrier to dislocation movement, thereby significantly enhancing the mechanical properties of the brazed joint. The highest shear strength of the Cf/C and superalloy brazed joint reaches 20.9 MPa using a CSAM NiTi75 interlayer, compared to only 6.1 MPa for the joint brazed with conventional NiTi75 powder filler. This work demonstrates the significant potential of CSAM-assisted brazing to enhance the mechanical properties of brazed joints, offering a novel approach to directly prepare brazing interlayers from metal powders.

In this work, a magnetic molecularly imprinted polymer with good adsorption capacity and a 2-methylimidazole (MI)-Cu-guanosine 5′-monophosphoric acid (GMP) nanozyme with high catalysis activity were first synthesized. Then, using the imprinted polymer as biomimetic antibody and the MI-Cu-GMP nanozyme as label, a novel direct competitive biomimetic enzyme-linked immunoassay (BELISA) method was established for the sensitive detection of acrylamide in foods. Under optimal conditions, the limit of detection (LOD, IC15) and sensitivity (IC50) of the BELISA method towards acrylamide were 0.02 and 4.52 mg/L, respectively. The BELISA method was successfully applied for acrylamide detection in spike potato crisp samples, with recoveries ranging from 87.50% to 106.67% being obtained. Further, the levels of acrylamide in coffee, fried dough twists and biscuit samples were determined by the BELISA and high performance liquid chromatography, with no significant difference found between the results of the two methods. This work thus introduces a novel, fast and accurate method for acrylamide detection in foods.

This study for the first time used synergistically double-sided probeless friction stir spot welding (SDP-FSSW) to repair the hole defects in a die-cast aluminum alloy ADC12 joints. Compared with conventional FSW repair methods, SDP-FSSW enables symmetric material flow from both sides without a probe, thereby promoting efficient defect closure while avoiding residual keyhole defects. Experiments showed that complete filling of holes could be achieved for joints (repaired zone) welded at a rotation speed of 1500rpm, dwell time of 4s, and plunge depth of 0.3mm. When the rotation speed or dwell time increased, the flash height increased as well, while joint thickness decreased, and the grains refined in the joint. At low heat-input parameters, repair relies on fine-grain filling, while at high heat-input parameters, it depends mainly on material flow. The hardness distribution of the joint shifts from “W” to “U” shape as the heat input increases. The increase in rotation speed or dwell time produced lower joint hardness.

This study used Linear Friction Welding (LFW) to join dissimilar titanium alloys joints of TC4/TC17, to investigate diffusion effects of interface elements and their relationship to phase transformations and nano-mechanical properties. Results showed that short-range diffusion of β-stabilizing elements like Mo and Cr occurred across the interface: with these elements migrating from the TC17 side toward the TC4 side. This movement induced the development of a narrow acicular band dominated by orthorhombic martensite (α′′). The transmission electron microscopy analyses confirmed that the α′′ phase exhibits a Burgers orientation relationship with both α and β phases on either side of the interface, demonstrating good crystallographic orientation inheritance following welding. Combined high-angle annular dark-field and energy dispersive spectroscopy analyses identified inside the recrystallized β grains on the TC17 side of depletion locally of β-stabilizing elements. In these grains nanoscale superlattice β precipitates were identified; which were consistent with β matrix and appeared as one-third order superlattice reflections in selected area electron diffraction patterns. However, in the TC4 side and further away from the interface, the lack of β stabilizers and cooling down below the β-transus temperature, produced solely equiaxed α instead of α′ grains. Nanoindentation measurements showed a graded range of mechanical properties across the interface, across α′′ > α > β, with α′′ showing the largest hardness value (4.96 GPa). These findings show the important role of β-stabilizer diffusion to interface phase transformations and its effects on mechanical properties locally, and provide essential insights into microstructural changes and allow to design for performance the TC4/TC17 linear friction welded joints.

AbstractIdiopathic pulmonary fibrosis (IPF) is a progressive, irreversible interstitial lung disease with an extremely high mortality rate. The FDA-approved oral nintedanib is a standard treatment requiring frequent long-term administration, causing poor patient compliance, plasma drug concentration fluctuations, and hepatotoxicity. To overcome the drawbacks of frequent dosing and unstable drug exposure, we developed nintedanib-loaded microspheres (NDNB-MS) with biphasic release profile, achieving sustained drug release for up to 55 days. Notably, during Phase I (0-7 days), drug release was primarily driven by surface dissolution and diffusion from the microsphere surface, achieving a 24-hour release of approximately 12% with no notable burst effect, thereby enabling prompt drug delivery. In Phase II (7-55 days), PLGA matrix degradation coupled with steady-state diffusion contributed to a constant drug release rate throughout this period, characterized by the absence of a plateau phase and without the gradual decline typically observed in later stages. In an IPF animal model, the biphasic release of NDNB-MS translated into distinct therapeutic benefits: the initial rapid release without burst effect enabled prompt drug delivery during the early phase, the sustained constant release phase provided continuous inhibition of the transforming growth factor-beta (TGF-β)/Smad2/3 signaling pathway, as well as long-term suppression of fibroblast-to-myofibroblast transformation, thereby preventing excessive extracellular matrix (ECM) deposition. This formulation overcomes key clinical drawbacks of oral nintedanib, providing a new drug delivery strategy for IPF that is long-acting, stable, and highly compliant, with significant clinical translational value and application prospects.

Androgenetic alopecia (AGA) is a highly complex disorder driven by a multifaceted pathogenesis encompassing androgen dysmetabolism, perifollicular inflammation, and microvascular deficiency. Consequently, conventional single-target therapeutics and passive microneedle delivery are fundamentally ill-equipped to reverse the degenerative follicular niche. Herein, we engineered a drug-free, zero-valent nano‑zinc bio-galvanic microneedle (Bio-MN) architecture to achieve a self-powered “electro-gas-chemical” microenvironmental remodeling in androgenetic alopecia. This size-customizable monolithic architecture features a concentric ring design—comprising a central zinc anode and a surrounding cathode array—that forms a structurally conformal primary battery, generating a radial micro-electric field for 360° coverage of the follicular niche. Upon dermal insertion, the interstitial fluid bridges the central zinc anode and the surrounding cathode array, autonomously triggering a sustained thermodynamic galvanic circuit. This self-driven system orchestrates a triple-synergistic therapy to accelerate the telogen-to-anagen transition: (i) the continuous and active release of zinc ions (Zn2+), driven by the primary battery, inhibits 5α-reductase-mediated dihydrotestosterone (DHT) synthesis, shielding hair follicles from androgenic attack; (ii) sustained microcurrents galvanotactically promote perifollicular angiogenesis and directly ignite the Wnt/β-catenin signaling cascade; and (iii) in situ-generated micro‑hydrogen (H2) via the cathodic galvanic reaction scavenges reactive oxygen species (ROS) and drives M2 macrophage polarization to quench inflammation comprehensively. In summary, this work transforms traditional microneedles from passive, inert depots into self-powered, active co-delivery architectures and pleiotropic microenvironmental orchestrators, ultimately offering a highly promising strategy for androgenetic alopecia.

The evolution of corrosion products and their influence on the fretting wear behavior of GH4169 alloy in a CO2 with 0.5 % SO2 at 800 degrees C was investigated. The corrosion behavior increased the sensitivity of GH4169 alloy to the displacement amplitude of fretting wear. At low displacement amplitudes, a dense and high-hardness Cr-rich oxide film effectively isolated the contact interface and enhanced wear resistance. At high displacement amplitudes, the Cr-rich oxide film ruptured and exposed the underlying Cr-depletion zone. Discontinuous Al2O3 internal oxide particles induced microcracks at stress concentration sites. Sulfidation behavior induced interfacial failure and activated third-body wear, which continuously aggravated material degradation.

A novel molecularly imprinted electrochemiluminescence (MIP-ECL) sensor was developed for the highly sensitive and selective detection of ciprofloxacin (CIP) in foods. The sensor was constructed through a rational multi-step modification of a glassy carbon electrode (GCE). Firstly, the novel luminescent metal-organic framework (MOF), Zn-perylene-3,4,9,10-tetracarboxylate (Zn-PTC), was synthesized and then coated onto GCE to generate an ECL signal. Subsequently, a cobalt-based metal-organic framework (Co-MOF) was synthesized and immobilized as a co-reaction accelerator, significantly enhancing the ECL intensity of the Zn-PTC system. Finally, a molecularly imprinted polypyrrole membrane was electropolymerized on the Co-MOF/Zn-PTC/GCE surface to provide specific recognition sites for CIP. This MIP layer effectively improved the sensor's selectivity, while the Co-MOF boosting strategy ensured high sensitivity. Under optimal conditions, the sensor demonstrated a wide linear range from 1.0 × 10-9 to 1.0 × 10-5 mol L-1 and a low detection limit of 7.7 × 10-11 mol L-1. The accuracy of the sensor was confirmed through recovery experiments in spiked canned luncheon meat and Angus beef meatballs, yielding satisfactory recoveries ranging from 93.40% to 106.25%. Furthermore, the detection results for chicken gizzard and grilled sausage showed excellent agreement with those obtained by high performance liquid chromatography (HPLC), validating the practical applicability of the proposed method.

This study develops an integrated framework combining coupled Eulerian-Lagrangian (CEL) simulation with experimental validation to systematically investigate synergistic double-sided probeless friction stir spot welding (SDP-FSSW) of 2198 aluminum-lithium alloy sheets under counter-rotational conditions. The simulation results reveal that the pronounced thermo-mechanical coupling and localized strain concentration induced by counterrotation are the dominant driving factors governing the microstructural evolution. The tracer-particle tracking results reveal that the opposing shear actions from the upper and lower shoulders drive the material to flow toward the lower and upper sides of the interface, respectively, thereby forming a Hook morphology with opposite upward and downward deflections. This feature is fundamentally different from the single-side deflected Hook commonly observed in conventional single-sided spot welding. Mechanical testing shows that the optimal joint performance is achieved at a welding force of 5 kN and a dwell time of 3 s, yielding a peak tensile/shear strength of 14.62 kN, approximately 62 % higher than that of conventional single-sided spot welding. Fracture analysis further indicates that, under counter-rotational conditions, the deflected Hook morphology enhances the effective load-bearing area and joint strength, while an excessively deflected Hook can promote crack propagation and drive the transition from shear fracture to plug-type fracture. These findings not only elucidate the previously unclear mechanisms of material flow and fracture behavior in SDP-FSSW, but also provide theoretical insight and practical guidance for the development of high-reliability friction stir spot welded joints in Al-Li alloys.

The rapid development of modern railways imposes higher requirements on the welding quality of seamless rails, and linear friction welding (LFW) is expected to become a preferred welding method. In this study, LFW experiments and finite element simulations were conducted on scaled-down U75V rail specimens to systematically reveal the microstructural and mechanical evolution and the underlying thermo-mechanical coupling mechanisms of the rail-profile joint. Experimental results indicate that the joint exhibits significant heterogeneity: the welding process leads to complete austenitization of the interface, and rapid cooling post-weld causes the weld zone (WZ) to transform into a mixed microstructure of martensite and pearlite. The thermo-mechanically affected zone (TMAZ) undergoes partial dynamic recrystallization, predominantly consisting of fine pearlite. Furthermore, the hardness and tensile strength distributions across the rail head, web, and base differ significantly, and the intricate plastic flow induced by the complex cross-section makes the joint susceptible to local unbonded defects. Finite element simulations confirm that the differences in thermal cycles, caused by the severely uneven distribution of the interfacial temperature field, are the fundamental cause of the microstructural heterogeneity. Meanwhile, the significant stress concentration near the interface at the rail head and base explains the local deterioration of mechanical properties. Based on the aforementioned mechanisms, this study clarifies the regulation direction for process parameters, providing a theoretical and empirical basis for exploring the engineering application of LFW in seamless rails.

Supra-carbon dots (supra-CDs) fundamentally expand the optical performance of carbon dot systems beyond just photoluminescence. Here, we report the first evidence of surface-enhanced Raman scattering (SERS) phenomenon in supra-CDs, discovered from a lamellar nano-assembly formed by polyphenol carbon dot coordinated with metal ions in a layered architecture (denoted as CML). Metal coordination remarkably alters the Fermi level that enables efficient charge transfer between CML and analyte, realizing the maximum Raman enhancement factor of 1.15 & times; 104. CML also retains the outstanding adhesive and reductive capabilities of polyphenol structure, which allows the in situ formation of CML@Au nanocomposites on the medical needle to fabricate SERS needle. The nanocomposites integrate electromagnetic and chemical enhancement mechanisms which endows the optical needle with coupling SERS effect. Then real-time in vivo tumor SERS monitoring is achieved via label and label-free modes utilizing this SERS needle as minimally invasive probe. In label-free mode, metabolic markers are extracted from tumor SERSome assisted by the deep learning algorithm, facilitating the precise evaluation of molecular components in tumorigenesis. Finally, the needle is functionalized with 5,5 '-Dithiobis-(2-nitrobenzoic acid) (DTNB) to serve as glutathione (GSH)-responsive SERS probe, enabling real-time monitoring of tumor microenvironment dynamics.

Synergistically double-sided friction stir welding (SDS-FSW) has the potential to mitigate through-thickness thermo-mechanical non-uniformity in medium-thickness aluminum joints, yet its linkage between process and property remains insufficiently understood. Here, SDS-FSW of 6061-T6 aluminum alloy is investigated via coupled thermo-mechanical simulation and experiments, with conventional sequentially double-sided FSW (CDS-FSW) as a benchmark. SDS-FSW converts two sequential asymmetric thermal cycles into a single intensified cycle and increases mid-thickness mixing, producing defect-free joints. The SDS-FSW joint achieves an ultimate tensile strength of 240 MPa, a yield strength of 159 MPa and an elongation of 5.2%, while reducing welding deformation by more than 55% relative to CDS-FSW. The results demonstrate that SDS-FSW is an effective route to improve joint homogeneity and mechanical properties in aluminum alloys.

This study presents a comparative failure analysis of low-cycle fatigue (LCF) behavior in 6061-T6 aluminum alloy joints fabricated by synergistically double-sided friction stir welding (SDS-FSW) and conventional sequentially double-sided friction stir welding (CDS-FSW). The cyclic deformation, damage evolution, and crack propagation characteristics were systematically evaluated under strain-controlled loading. Both joints exhibited elastic response at 0.15% strain amplitude and pronounced cyclic hardening beyond 0.25%. However, the CDS-FSW joints showed consistently lower peak stress amplitudes and reduced hardening capacity, indicating inferior resistance to cyclic deformation. Increasing strain amplitude accelerated plastic strain energy accumulation and fatigue damage. Despite exhibiting higher plastic strain energy density, SDS-FSW joints achieved longer fatigue life due to their improved microstructural uniformity and reduced crack growth rate. Fractographic analysis revealed that CDS-FSW joints exhibited larger fatigue striation spacing and more rapid crack propagation, whereas SDS-FSW joints showed finer striations and more stable ductile fracture characteristics. The results establish a direct link between welding-induced thermo-mechanical conditions and fatigue failure mechanisms, providing insights for durability assessment and structural reliability of double-sided friction stir welded aluminum components.

This study aims to investigate the potential of employing a developed method of Double-sided Friction Stir Welding (DS-FSW) to butt-join (similar joint) 2024-T3 aluminum alloy plates with a reasonably thin thickness. The developed DS-FSW eliminates the utilization of sequential passes that the conventional DS-FSW process requires. Instead, it utilizes two identical tools and symmetrically aligns them in a manner that the pins’ tips face each other perpendicularly. Thus, both tools can perfectly work synergistically, and this approach can be referred to as Synergistic Double-Sided Friction Stir Welding (SDS-FSW). Coupled Eulerian Lagrangian (CEL) method was formulated into a Finite Element (FE) model to predict thermal distribution and material flow patterns, providing insights into good agreement with mechanical tests. The J-C plasticity model defined the material’s elastic-plastic properties during the welding stage. Microstructures of the joints were photographed using a digital Optical Microscope (OM), and mechanical properties were tested to assess the joint’s integrity through tension and microhardness testing. The rotating and welding speeds were optimized using a bottom-up approach with two factors and four levels, resulting in 600 rpm and 200 mm/min as the most ideal process parameters. OM images indicate that the greater rotating and welding speeds result in an increased heat input, which weakens material bonding. As a result, it causes a kissing bond and scribble flimsy line to an inner defect in the stir zone (SZ). Most of the tensile samples exhibit brittle characteristics with pulse-like crack patterns, and many of them fracture in the SZ, with an average Ultimate Tensile Strength (UTS) of 55 500^∘ C (slightly below BM’s solidus temperature). The material flow was profiled like an imperfect vortex due to the weak driving intensity generated by the tool, especially from the pin. The insufficient pin’s height dimension reduces the pitch number and the root cavity of the pin’s thread as well, which has an impact on the swept volume. It’s crucial to make significant improvements in the upcoming studies to maximize the performance of the tool design and rearrange the tools’ alignment to gain the double heat input.

The high carbonization of carbon-based nanozymes makes them have poor hydrophilicity, and the dispersion in aqueous solution or biological medium is not ideal, which restrains their applications. In this work, we synthesized a novel ultra-thin copper/nitrogen doped carbon coated with Mo2N nanoparticles (Mo2N@CuNC) by pyrolysis of two-dimension Mo/Cu@ZIF, which was obtained via ion exchange using Na2MoO4 as the secondary metal source and morphology regulator on the basis of Cu@ZIF-L. Mo2N@CuNC showed significantly improved water dispersibility and excellent peroxidase-like and ascorbic acid oxidase-like activity. Based on the dual-enzyme mimicking activities of Mo2N@CuNC, a ratiometric colorimetric sensing platform for nitrite determination and a ratiometric fluorometric sensing platform for highly selective ascorbic acid determination were designed, respectively. Additionally, smartphone-assisted visual detection was successfully realized, demonstrating the great application prospects of dual-enzyme mimics in food and environmental analysis.

This study investigates linear friction welding of GH4169 alloy for aero-engine integrally blisks, with particular focus on elucidating the mechanisms by which combined pre- and post-weld heat treatments influence microstructural evolution and corrosion behavior of welded joints. Microstructural characterization reveals that composite heat treatment promotes the formation of large-scale spherical u03B3u2032 and disc-shaped u03B3u2032u2032 phases in the Base Material (BM), while in the Thermo-Mechanically Affected Zone (TMAZ), original precipitates coarsen and fine u03B3u2032 and u03B3u2032u2032 phases reprecipitate. Additionally, needle-like u03B4 phases precipitate along grain boundaries. The synergistic effect of grain refinement and precipitation strengthening results in superior joint mechanical properties, including a microhardness of 540 HV0.5, a tensile strength of 1400 MPa, and a fracture elongation of 18%, with the joint strength comparable to that of the BM. Electrochemical analysis shows that the joint exhibits significantly lower corrosion resistance than the BM, due to enhanced micro-galvanic coupling between the u03B3-matrix and precipitated u03B3u2032 or u03B3u2032u2032 phases. This is evidenced by an increase in corrosion current density from 1.62u00D710-6 A/cm2 of BM to 3u00D710-6 A/cm2 of joint. High-temperature molten salt corrosion tests indicate that corrosion mainly occurs through the combined action of oxides and soluble salts. The joint shows accelerated corrosion, reaching a peak value in the average corrosion rate of 269.9 g/m2/h, characterized by a fine-grained microstructure and loosely oxide films. The electrochemical impedance of these is measured at 1.83 ku03A9 u00B7cm2, attributed to thermo-mechanical effects. In contrast, the coarse-grained BM forms dense and protective oxide layers, with a higher impedance of 14.20 ku03A9 u00B7cm2 and a lower peak corrosion rate of 134.9 g/m2, reflecting more stable corrosion behavior. This work deciphers how heat treatment controls corrosion resistance through the regulation of precipitate distribution in welded joints, providing valuable guidelines for the optimization of integrated welding and heat treatment process in blisk production.

Herein, we introduce a novel lighting-up fluorescence immunoassay, designated as d-AIENPs-LFIA, for the synchronous detection of Escherichia coli O157:H7 and Salmonella typhimurium utilizing ultrabright red-emitting aggregation-induced emission nanoparticles (AIENPs) as signal-amplification probes in a lateral flow immunoassay (LFIA). Under the developed conditions, the d-AIENPs-LFIA demonstrated exceptional sensitivity, enabling highly sensitive synchronous detection of E. coli O157:H7 and S. typhimurium within 15 min, with detection limits of 396 and 236 CFU/mL, respectively. This d-AIENPs-LFIA exhibited good reproducibility, with average recoveries of 83.7 % to 113.0 % and coefficients of variation below 15.83 %. Furthermore, the practical applicability of the d-AIENPs-LFIA was further demonstrated in complex food matrices, including lettuce, skim milk powder, and milk samples. Notably, by incorporating a pre-incubation step, the sensitivity of the d-AIENPs-LFIA was significantly enhanced to 1 CFU/mL within 6 h, offering substantial potential for routine rapid screening of foodborne pathogens.

Obesity, characterized by excessive lipid storage, has become a global epidemic that severely impacts health and quality of life. Current anti-obesity strategies have encountered a range of challenges and limitations in practice. Metal clusters have recently emerged as a novel class of nanomaterials, with excellent enzyme-mimicking properties and highly effective in scavenging reactive oxygen species (ROS). In this study, atomically precise Au25 clusterzymes encapsulated dissolvable microneedles (Au25@DMNs) as the transdermal drug delivery system are developed to treat high-fat diet (HFD)-induced obesity. After six weeks of treatment (once every two days), the Au25@DMNs group showed a significant reduction in weight gain, with a 21% decrease compared to the HFD group. Au25@DMNs treatment also effectively reduced fat accumulation, improved glucose homeostasis, and alleviated lipid metabolism disorders. Especially, Au25@DMNs treatment significantly mitigated chronic inflammation in white adipose tissue (WAT) and even alleviated systemic inflammation. Further studies revealed that Au25 clusterzymes from Au25@DMNs neutralized microenvironmental ROS, which in turn triggered WAT browning via the AMPK/PGC-1α pathway, thus achieving high efficiency in anti-obesity. These findings demonstrate that transdermal delivery of clusterzymes via dissolvable microneedles can effectively induce WAT browning and thermogenesis, thus providing a new platform for combating obesity and related metabolic disorders.