Volume 32, Issue 1

In the present research, the nanosecond short-pulsed laser with rotary drilling method was designed to process carbon fiber-reinforced polymer (CFRP) composite plate. The hole dimension, surface morphology, heat-affected zone (HAZ), and mechanical properties were analyzed. The results reveal that the CFRP composite plate could be rapidly drilled with highly qualified processing surface by the nanosecond short-pulsed laser with rotary drilling method. The figures such as circle, square, triangle, and regular hexagon could be processed with minimum hole diameter of 0.1 mm. The changing of laser scanning speed and laser power could result in the variation in diameter of hole entrance and exit, which fluctuates in scope of 35 μm. The calculated biggest taper angle is about 0.43°, but the smallest taper angle is about 0.12°. The laser drilling on CFPR composite decreases the tensile strength by about 9%, which should be ascribed to the damage of continuous carbon fiber, but it is still acceptable. The nanosecond short-pulsed laser with rotary drilling method generates a small HAZ on hole entrance but almost no HAZ in hole exit. The surface roughness of laser processed CFRP ranges from 2.925 to 4.226 μm. Comparatively, the laser scanning speed between 800 and 1,000 mm/s and laser power around 28 W would be the optimal choice, which could realize the best balance between surface quality and efficiency.

Porous silicon (PS) has been widely used in biology, biomedicine, and nanotechnology. In recent years, its application in cancer therapy has received considerable attention. PS has shown low cytotoxicity, so it is reasonable to use it as an antibody conjugate for targeted anticancer drug delivery. In this work, we synthesized PS covalently attached to doxorubicin and covered by a nanometric polymer as a crosslinker between PS and the monoclonal antibody trastuzumab, using electrochemical etching for particle generation. The results revealed the formation of the antibody conjugate, obtaining particles with sizes around 250–350 nm, and a homogeneous size distribution determined by dynamic light scattering. Scanning electron microscopy (SEM) analyses showed the porous structure of the conjugate, while Fourier-transform infrared and transmission electron microscopy characterization demonstrated functionalization between PS and the antibody. The cytotoxic effect was evaluated against two breast cancer cell lines, SKBR3 (HER2+) and MCF-7 (HER2−), and one non-cancer cell line as control (HEK293). The cytotoxic effect on the SKBR3 cancer cell line was higher than on the MCF-7 and HEK293 cell lines. Notably, the targeted protein HER2 mediates the elevated cytotoxic activity exhibited by the antibody conjugate. Graphical Abstract

Based on the generalized thermoelasticity theory, the influence of initial stress and imperfect thermal interfaces on the static and dynamic problems of the simply supported thermoelastic laminated plate is investigated. Besides adopting the spring-layer model for the elastic field, the thermal conditions at the interfaces are also described as weak or high thermal conducting conditions. By employing the state-space method and introducing the interface transfer matrices for both elastic and thermal fields, this approach is convenient and efficient for multi-layer or thermoelastic coupled structures. Numerical results are presented to verify the correctness of the formulations, and the effects of initial stress and imperfect interfaces on various field variables in the structure under free vibration and static bending are illustrated.

Carbon fiber-reinforced polyether ether ketone (CF/PEEK) is commonly used in the aerospace industry due to its high specific strength. The laser-assisted forming process shows potential to enhance the efficiency of forming thermoplastic composites and enabling in situ forming. However, when forming CF/PEEK corner structures with laser assistance, the shape accuracy of the part is limited by the spring-back resulting from prepreg bending. This article focuses on investigating the phenomenon of bending spring-back in thermoplastic composite parts. Through laser-assisted heating forming experiments and finite-element simulations, the effects of laser power and forming rate on the spring-back angle of single-layer CF/PEEK parts are analyzed. The process parameter distribution curve for achieving the minimum spring-back angle is determined. The corner structure demonstrates the least spring-back deformation, with a spring-back angle of 1.77°, at a forming rate of 1,700 mm/min, and a laser power of 63 W. At lower temperatures, the spring-back deformation is mainly influenced by the residual stress. The main mechanism of spring-back deformation of resin at high temperatures is the increase of bending caused by deconsolidation. This study offers theoretical guidance for achieving precision molding of multilayer thermoplastic composite bending structures.

Al–0.6Mg–0.5Si (wt%) alloys with varying Y contents are prepared, and effects of Y on the microstructure, electrical conductivity, and mechanical properties are investigated. The results show that Al–0.6Mg–0.5Si alloys are refined by addition of Y, and the average grain size is refined from 254 to 168 μm with the addition of Y content from 0 to 0.4 wt%. Addition of Y can lead to the formation of the AlSiY phase and AlFeSiMgY mixed phase as Y can react with elements such as Fe and Si in the alloy. The electrical conductivity of Al–0.6Mg–0.5Si alloys initially increases and subsequently decreases with increasing Y content. The electrical conductivity reaches its highest value of 54.3% IACS by addition of 0.3 wt% Y, which is improved by 4% compared with that without addition of Y. The tensile strength increases with increasing Y content, and the highest value is 154 MPa by addition of Y with 0.4 wt%, which is improved by 12.4%. Elongation of alloys initially increases and subsequently decreases with increasing Y content. The strength improvement of Al–0.6Mg–0.5Si alloys is mainly attributed to grain refinement and precipitation of granular and short rod-like secondary phases caused by the addition of Y into Al–0.6Mg–0.5Si alloys.

In order to explore the feasibility of the structural health monitoring on the in-service anchor system for carbon fiber-reinforced polymer (CFRP) strand wires, the relative theoretical analysis and experimental tests were conducted. The piezoresistive model for CFRP strand wires was established by theoretical deduction. The damage model of the anchor system at different load stages of the anchorage zone was established by theoretical derivation. Thereby, the regional distribution monitoring methodology of the anchor system was established based on the above two models. The tensile experiments on the anchor system for the CFRP strand wires were carried out, and the typical mechanical and electrical features were ascertained, including volt–ampere characteristics, resistance–strain relationship, strain sensitivity, and the distribution of shear and tensile stresses along the anchorage zone. The results show the theoretical results are in line with the experimental measurements, with a maximum error of below 15%. This indicates excellent applicability and reliability of self-monitoring on the anchoring systems throughout loading.

Nanocomposite polyurethane (PU) materials have broad application prospects in the fields of optics and artistic colors, but there are few systematic studies on the application of nano-titanium dioxide (TiO₂), nano-zinc oxide (ZnO), and nano-silver (Ag) in PU matrices. The aim of this study is to prepare a PU matrix with the same transmittance but better UV absorption by adding these nanoparticles to improve the optical properties and UV resistance of the material. In this study, the solution method was used to prepare and characterize nano-TiO 2 , ZnO and Ag particles, and their addition amount and dispersion state were precisely controlled to prepare composite materials with different mass fractions. The properties of these composites were comprehensively evaluated by UV-visible spectroscopy analysis, transmission electron microscopy observation, and color measurement methods. The results showed that nano-TiO₂ significantly improved the transparency and UV blocking ability of the material, nano-ZnO enhanced the UV stability, and nano-Ag improved the transparency, antibacterial properties, and color stability. The specific data are as follows: the transmittance of nano-TiO 2 and ZnO dropped from 85 to 55%, respectively, and the transmittance of nano-Ag dropped from 90 to 60%; in terms of ultraviolet absorption rate, nano-TiO 2 increased from 10 to 45%, ZnO increased from 15 to 50%, and Ag increased from 20 to 55%. In addition, the study evaluated the effects of UV irradiation on the optical properties and color stability of the nanocomposites and found that the addition of nanoparticles significantly improved the material’s resistance to UV aging. In summary, the kind and location of nanoparticles have a substantial impact on the properties of PU composites. This study provides a scientific basis for the creation of high-performance nanocomposite PU materials.

The effect of 200 days of cyclic weathering test (CWT) and 1,000 h of salt spray test (SST) on the performance of polyurethane (PU) coating was investigated. A 200 μm coating was applied to a composite and cured before CWT and SST ageing studies. CWT was conducted in ten cycles (each cycle: −40°C for 5 days, 70°C for 5 days, 40°C and 90% RH for 5 days, and salt fog for 5 days). Initial water immersion tests concluded that the coated specimens have 37% less water absorption than uncoated specimens. The degradation behaviour of the coating was evaluated by measuring pull-off adhesion strength, critical load from the scratch test, and wear depth from the pin-on-disk test. Similarly, the surface characteristics of the coating were studied by SEM, gloss value, and contact angle. CWT ageing caused a decrease in gloss value (93–78 GU), pigment content (18–8 wt%), contact angle (92–70°), and an increase in wear depth at 20 N of applied load (45–200 µm). Similarly ageing also decreased the pull-off adhesion strength to 6.77 MPa (CWT) and 7.93 MPa (SST). CWT and SST also decreased the thermal stability by 11–13°C, considering 5 wt% loss and tensile strength of the coating from 42 to 29 MPa. The damage to the composite substrate was not significant due to prolonged exposure periods under CWT and SST, though the damage was noted in PU coating, like increased surface roughness and wear depth.

Carbon fiber-reinforced polymers (CFRP) are widely used in aeronautical and engineering fields because of their excellent mechanical properties and lower manufacturing costs. Among them, resin–matrix composite material is one of the widely used material types. In this study, the effect of the opening behavior of composite laminates under different hygrothermal aging conditions on their compression properties was studied. At the same time, the finite-element analysis method is used to numerically simulate the hygrothermal aging process and compression experiment. It is found that the hygroscopic behavior in the hygrothermal aging process is compounded by Fick’s second law. After the compression experiment, it is further found that aging time is the main reason affecting the mechanical properties of materials. At the same time, the failure caused by compression behavior mainly occurs laterally along the opening until brittle failure occurs.

Pumice aggregates stand out with their low density and high porosity. However, their high water retention capacity and low mechanical strength are the primary disadvantages limiting their use in lightweight concrete production. In this study, pumice aggregates with particle sizes ranging from 4 to 16 mm were coated with polyester, known for its superior adhesion and insulation properties, to produce polyester-coated pumice aggregates. Subsequently, five different lightweight concrete mixtures were prepared using 450 kg/m³ cement, incorporating coated and non-coated pumice aggregates as coarse aggregates at replacement ratios of 0, 25, 50, 75, and 100%. Aggregate tests included specific gravity and water absorption, while fresh concretes were evaluated for unit weight and slump. Hardened concretes were tested for dry unit weight, water absorption, ultrasonic pulse velocity (UPV), compressive strength, freeze–thaw resistance, and thermal conductivity. The results revealed that the polyester coating increased the specific gravity of pumice aggregates by up to 45% and reduced water absorption by 85%. The use of coated aggregates increased the unit weight of the concrete but resulted in a reduction in compressive strength and UPV. Despite a compressive strength reduction of up to 58% depending on the coated aggregate content, concrete specimens produced with polyester-coated aggregates exhibited the highest performance in terms of freeze–thaw resistance and thermal conductivity.

The methylammonium iodide lead chloride-reduced graphene oxide (MAI:PbCl 2 -rGO) was prepared via the dipping deposition. In this work, the rGO composited in MAI:PbCl 2 was introduced with different weight percents (wt%) between 7 and 10 wt%. All samples have been investigated via Fourier transform infrared, ultraviolet−visible spectrophotometer spectroscopy, scanning electron microscopy, X-ray diffraction (XRD), and the Hall effect to illustrate optical properties, morphological, and electrical properties. The XRD analysis result revealed that the mean grain size of MAI:PbCl 2 is 27.46 nm, whereas a suitable crystallite size of 38.07 nm (and has a uniformity crystallite) is the case of the MAI:PbCl 2 -8wt%rGO obtained, leading to the lowest micro-strain of 0.15. Besides, the activation energy determined from the nature logarithm of conductivity and 1,000/ T by using the temperature-dependent electrical transport data was displayed in a temperature range of 298–323 K. It was found that MAI:PbCl 2 -8 wt% rGO decreases the activation energy to 0.26 eV as well as yields the maximum conductivity of 72.55 S/cm. In this way, adding suitable rGO to MAI:PbCl 2 is key to obtaining higher conductivity, which is used to ascertain and describe the nature of the semiconductor material.

Multifunctional characteristics are of significance for development of bionic skin materials. Herein, we report the collagen fibers (CFs) as biomass templates constructed multifunctional polyvinyl alcohol composite films (PCBPP) that integrate the diverse properties including the good thermal stability, water resistance, self-healing ability, adhesiveness, benign biocompatibility, and sensitive electrical signal response within a single structure, realize much more favorable functionalities in mimicking natural skin. The CFs as biomass template well immobilize and stabilize the polypyrrole (PPy) nanoparticles, which simultaneously improves the dispersity of PPy and enhances its conductivity. More importantly, due to the CFs constructed conductive paths and micro- and nano-sensing structure, the PCBPP prepared e-skin exhibits the GF value of 0.366 in the strain range of 10–40% and is able to distinguish different strain intensities and monitor the movements of the human body, including wrist bending, elbow bending, and swallowing. The self-healed PCBPP prepared e-skin exhibited the recoverable sensitivity. Our investigation provided a new prospect for designing CFs as conductive network packed multifunctional composite film and the as-prepared PCBPP exhibits great potential for versatile applications in various wearable devices and in the field of artificial intelligence.

This study investigates the risk of early-age cracking in cemented sand gravel by modeling it as a two-phase material (aggregate and mortar) from a mesoscopic perspective. A mathematical model incorporating mesoscopic components was developed to simulate the temperature stress field under different heat dissipation conditions. Key findings include: (1) Early-age heat release occurs primarily in the mortar, leading to uneven temperature distribution (low in aggregate, high in mortar), which becomes uniform as hydration ends. Stress concentration is observed at aggregate–mortar interfaces. (2) Mesoscopic component consideration reveals local stress concentration, unlike models ignoring meso-components. (3) External heat dissipation conditions significantly affect temperature effects. Under adiabatic conditions, larger deformations occur at mortar–aggregate intersections and increase over time. In heat dissipation states, deformation is higher at boundaries, unevenly distributed, and decreases over time. This research highlights the importance of mesoscopic considerations in understanding and mitigating early-age cracking risks in cemented sand gravel.

Ceramizable silicone rubber (SR) composites, which transform into high-strength ceramics at high temperatures, are crucial for fire-resistant applications. This study investigates the synergistic effects of ammonium polyphosphate (APP) and zinc borate (ZB) on the mechanical properties and thermal stability of ceramizable SR composites. The results show that the addition of APP and ZB significantly enhances the flexural strength and thermal stability of the composites at high temperatures, while maintaining their elasticity and electrical insulation properties at room temperature. The synergistic effect of APP and ZB leads to the formation of a liquid phase at high temperatures, which binds the residual materials and promotes the formation of mullite and aluminum borate crystals, resulting in a high-strength ceramic matrix. The composite exhibits excellent elongation at break (492.36%) and electrical insulation (volume resistance of 1.89 × 10 14  Ω m) at room temperature, and a flexural strength of 39.47 MPa after heat treatment at 1,000°C.

This work presents a comprehensive analysis of buckling stability of axially functionally graded material (AFGM) heavy columns with nonprismatic solid regular polygon cross-section (RPCS) and constant volume. First, this study formulates the explicit stiffnesses of AFGM member with nonprismatic solid RPCS, with a particular focus on flexural rigidity and mass per unit length. Furthermore, the formulated stiffnesses are applied to the buckling stability of the column with its own weight, called heavy column. The differential equation which governs the bucked mode shape of such column is derived, along with the boundary conditions. Numerical solution methods are presented to compute the buckling load and its buckled mode shape. This study provides a detailed presentation of the buckling loads, which are compiled into comprehensive tables and visualized through various figures. An extensive parametric study highlights the influence of geometric and material properties on buckling performance, fostering discussions on the implications for design and application in structural engineering.

In this study, a carbon fibre-reinforced polyamide 6 crash box was designed, manufactured, and crash-tested as part of a novel automotive front-end structure, developed in the EU-Project SALIENT. The crash box concept, design, and manufacturing process were based on previous investigations reported. This prior research enabled the efficient definition of key design parameters, including inner diameter ( D i {D}_{i} ), wall thickness ( t t ), trigger design, and an optimized fibre lay-up. The crash box features an innovative combination of thermoplastic composite material and an advanced manufacturing method – laser-assisted tape winding – to enable precise, automated production of reusable structures. It was tested under crushing conditions to explore further applications for the inversion mechanism, as described in the literature, to enhance crash performance and improve energy absorption. The use of a thermoplastic matrix (PA6) helped to minimize dust and particle generation, contributing to improved health and environmental safety. Additionally, the use of this material enhances recyclability, and the long service life of the composite allows for potential reuse of the structure at the End of Life in future vehicle generations.

This study investigates the nonlinear structural behavior of axially functionally graded material beams composed of steel and aluminum through a systematic computational approach. Three absolute nodal coordinate formulation (ANCF)-based approaches were applied: the first employs a planar ANCF shear deformable beam element, the second utilizes an enhanced continuum mechanics-based ANCF element, and the third leverages a higher order ANCF beam element. The research methodology follows a rigorous stepwise analysis: first, the accuracy of the ANCF beam elements was verified through a convergence study; second, a large deformation analysis was carried out focusing on the effect of material nonlinearity; third, comprehensive buckling analyses were conducted, including both nonlinear postbuckling evaluation using Crisfield’s arc-length method and nonlinear eigenvalue buckling estimation via a dichotomy scheme, identifying the complex nonlinear behavior and demonstrating the variation in critical loads depending on material gradation profiles, respectively. The overall results demonstrate the ANCF framework’s effectiveness in capturing complex geometric and material nonlinearities. This study highlights the mechanical tradeoffs between steel dominated regions and aluminum rich zones, providing insights for the design of graded structural components in advanced engineering applications. It was also found that the ANCF-based higher order beam element provides more accurate and reliable deflection curves than other beam models.

Using crumb rubber (CR) from end-of-life tyres in concrete offers a practical way to reduce environmental waste while enhancing specific performance characteristics. This review brings together current findings on how CR affects the fresh properties, strength, durability, and microstructure of concrete. It explains how untreated rubber often reduces compressive strength, especially at higher replacement levels, due to poor bonding and internal voids. However, this performance drop can be significantly reduced through surface treatments like alkali washing and the use of supplementary cementitious materials. These combinations help restore strength, improve resistance to chloride attack and freeze–thaw cycles, and lower permeability. Microstructural studies show that refining particle size and improving the rubber–cement interface lead to a denser and more cohesive matrix. A classification system is proposed to guide practical applications based on the amount of rubber used and the required mechanical and durability properties. When properly designed, rubberized concrete can reduce embodied carbon by up to 25% and eliminate the need for natural aggregates in many applications. The review also outlines areas that need further attention, including long-term performance validation, lifecycle modeling, and development of practical mix design standards to support the wider use of rubberized concrete in construction.

Baloxavir marboxil (BXM) is a new antiviral drug that inhibits the cap-dependent endonuclease required to replicate the virus. The efficacy, quality, and safety of drug products and active pharmaceutical ingredients (APIs) may be compromised by impurities. To ensure the safety and quality of medications, it is essential to test APIs and drugs for impurities. Methods for analyzing and detecting BXM intermediates and impurities are currently unknown. Therefore, it is crucial to implement analytical methodologies and ensure the quality control of intermediates and associated compounds during the medication manufacturing and storage processes. This is necessary to enhance the overall product quality of BXM, improve its therapeutic efficacy, and reduce potential adverse effects. High-performance liquid chromatography (HPLC) was utilized to detect and quantify impurities in BXM and its intermediates in this study. The impurities were removed using column chromatography and characterized using mass spectrometry and nuclear magnetic resonance. Based on the spectral data, the structures of impurities were identified as 3,4-difluoro-2-benzenesulfinyl methyl benzoate and methyl 3,4-difluoro-2-(benzoyl oxymethyl) benzoate. A highly efficient HPLC method was designed and validated to assess its accuracy, linearity, specificity, and precision. As mentioned earlier, the results demonstrated that the methodology exhibits specificity, accuracy, and precision, with a separation degree of ≥1.5, making it suitable for routine analysis. Furthermore, the source of BXM impurities and its intermediates was confirmed by analyzing their underlying mechanism. The separation, structure identification, and mechanistic analysis of impurities are crucial in efficiently managing impurities in BXM and its intermediates. It provides technical assistance for the quality control of BXM, thereby ensuring the drug’s safety.