Fiber-reinforced composites have provided tremendous opportunities in advanced engineering materials, but the fiber generation and spatial distribution are the most challenging aspects. This paper proposes a novel fabrication approach for fiber-reinforced composites with spatially resolved fiber distribution by combining immersion and near-field electrospinning. The new Immersed Electrohydrodynamic Direct-writing (I-EHD) process makes use of an electrostatic force to draw ultrafine fibers and allows the freestanding of electrospun fibers all inside a liquid matrix. This novel approach enables the dynamic control of fiber morphology and 3D spatial distribution inside the composites, which may lead to future scalable 3D printing of multifunctional composites.Graphical abstract

Struvite or magnesium ammonium phosphate hexahydrate (H16MgNO10P) was synthesized in the presence of sodium alginate to determine the impact of extracellular polymeric substances (EPS) on struvite formation. Bulk crystallization of struvite at a 1.3:1:1 molar ratio of Mg:N:P, respectively, showed that in the presence of increasing sodium alginate concentration, struvite crystal habit changed from prismatic to plate-like twinned morphology. A possible mechanism of the adsorption of sodium alginate at [001]cc facets of struvite is proposed.Graphical abstract

Bacterial infections are one of the major causes of surgical implant inefficiency and failure. Herein, we present a Nanocomposite (NC) produced by the addition of Poly(N-vinyl carbazole)-Graphene Oxide dispersion (PVK-GO) as a nanofiller to a commercial photopolymer acrylate resin and 3D printed as coatings via the Digital Light Processing technique. Characterization and bioassay results against Escherichia coli and Staphylococcus aureus confirmed the elevated thermomechanical properties and efficient antibacterial activity of the printed NC-based coatings. The present study demonstrates the fabrication and optimization of a PVK-GO-based NC and its potential utilization as a 3D-printable material for biomedical applications. Graphical abstract

This study investigates the optimization of nickel-infused alumina nanostructure for enhanced solar-thermal energy conversion. The optimization is based on the analytical model using the transfer matrix method, which is first validated with experimental results and then compared with a finite element model. The optimal nanostructure of the solar absorber shows a high solar absorptance of 0.87 and a low thermal emittance of 0.08. The optimal design can achieve a total net heat flux of 815 W/m2, approximately 26% higher than the nominal value of 647 W/m2 corresponding to the baseline design.Graphical abstract

We describe a novel excimer laser-based route for the fabrication of crystalline MoS2 nanoneedles. Laser annealing of MoS2 thin films at a low energy density of 0.08 Jcm−2 resulted in a closed-pack structure with low defects and excellent conductivity due to melting and rapid quenching. A further increase in laser annealing energy density resulted in the formation of MoS2 nano-needles. This structure of MoS2 was found to have a remarkable reduction ability for H2O2 at − 0.14 V over a wide linear range; a low detection limit (0.45 nM (S/N = 3)) and sensitivity of 2.38 μA/mM cm−2 were demonstrated. Graphical abstract

Mechanical tests for various skins showed that the experimental stress–strain curves under uniaxial tension are composed of two regimes with different deformation mechanisms. However, the existing constitutive relations often suffer from incomplete characterization of full-range deformation. Herein, a merging constitutive relation is applied to describe these two regimes. The constitutive relation is first validated by comparing the identified constitutive parameters with the references then applied to predict the experimental results of typical skins, and it indicates that the present relation can be robust and accurate characterization of full-range behavior of skins.Graphical abstract

Gold metallization of 3D printed polymer structures was conducted by a supercritical carbon dioxide (sc-CO2) assisted electroless plating process. Precursor of the Pd catalyst utilized in this study was palladium bis-hexafluoroacetylacetonate for the high solubility in sc-CO2. A Ni–P layer was first formed on the catalyzed polymer structure as a sacrificial layer for the sequential gold deposition. Electrical resistance of the gold metallized 3D printed structure was 0.15 Ω and slightly increased to 0.18 Ω after a tape adhesion test. The fracture strength was 47.6 MPa for the sample with 45 min of the gold deposition time. Graphical abstract

We report on magnetic amorphous (Fe0.85Nd0.15)0.6B0.4 nanoparticles showing an enhanced thermagnetic stability regarding to their size, with a blocking temperature higher than room temperature. Magnetization and Mössbauer spectroscopy results suggest that the ideally spherical nanoparticles conformation is almost equally distributed between an ordered core and an iron oxide shell (Fe2O3). Magnetization measurements are described by a phenomenological model comprising a ferromagnetic core represented by the Bloch´s law and a magnetically disordered contribution obeying the Curie law. The interaction of the core with the oxide shell would be enough to thermally stabilize the nanoparticles against superparamagnetism.Graphical abstract

Quartz crystal microbalance-based humidity sensors with sensing layer of bamboo cellulose (BC)-overlaid polyacrylonitrile (PAN) nanofibers were fabricated using electrospinning and drop-casting processes. Scanning electron microscopy, water contact angle measurement, and Fourier-transform infrared spectroscopy were employed to investigate the morphology, wettability, and chemical composition of the nanofibers, respectively. Impact of varying BC concentration on the sensing response toward relative humidity (RH) was evaluated, where higher BC concentration resulted in more responsive sensor behavior (higher-frequency shift) toward RH. This work highlights a simple method to enhance the humidity-sensing ability of electrospun nanofibers by overlaying them with hydrophilic materials. Graphical abstract

Reducing the mass of elements of electrical engineering products while preserving their electrical characteristics is an urgent task. So, it is important to create new composite materials that can provide decide this. For functionalization of electrical properties were created a LaNi5 + carbon nanotubes composite. It is shown that at a concentration of 15 wt.% nanotubes there is a 13-fold increase in electrical conductivity due to the charge transfer from metal particles to CNTs. Graphical abstract

The presented study is focused on the evaluation of Poisson’s ratio and Young’s modulus of solid composite materials with internal architecture represented by planar geometrical patterns. These patterns are characterized by low and high Poisson’s ratios when taken as solid/empty space composites. The mechanical properties are studied theoretically using the finite element method and also experimentally on samples produced by 3D printing from polymeric materials. The results show that tested geometrical patterns are able to decrease Poisson’s ratio when implemented in the solid composite regardless of their performance as solid/empty space composites. A decrease of Poisson’s ratio is more significant compared to the corresponding law of mixtures. Graphical abstract

Colorectal cancer, which is difficult to treat and has a high recurrence rate, is a challenging target. Here, we propose a novel multi-layered sheet-like device with photothermal switching for the achievement of both hyperthermia and local chemotherapy. The device was fabricated by modifying polydopamine on the surface of a polymer thin film (nanosheet) and combining it with a drug-loaded poly(lactic acid) nanosheet, and was demonstrated to control the drug release reversibly. It is suggested that several percent of loaded drug was repeatedly released by irradiating near-infrared light, indicating the high potential of minimally invasive long-term treatment of colorectal cancer. Graphical abstract

MXenes are a large family of two-dimensional nanomaterials with diverse properties and potentials for electronic, photonic, energy storage, and other applications. Due to their hydrophilicity, MXenes capture water from the surrounding environment, which may lead to swelling and degradation of the assembled multi-layer films. Here we demonstrate that intercalation of N-methylformamide (NMF) leads to MXene films with improved stability at high temperatures and high humidity through host–guest hydrogen bonding. Due to strong interaction with MXene surface and occupation of the interlayer spacing, NMF mitigates intercalation of water and allows for better retention of electrical conductivity during prolonged use in hot and humid environments.Graphical abstract

The effect of small amounts of copper oxide, manganese oxide, and stainless steel as sintering additives on the sintering behavior and mechanical properties of Alumina Toughened Zirconia (ATZ, 3Y-TZP with 20 wt% Al2O3) ceramic composites were evaluated and contrasted with that of undoped ATZ by using microwave sintering (MW) method. Green bodies were sintered at 1250°C, 1350°C, and 1500°C using a holding time of 5 min., with a heating rate of 30°C /min. In general, all ATZ samples exhibited a similar trend, as the results showed that the relative density and mechanical properties increased with increasing sintering temperature regardless of the addition of dopants. It was found that the addition of 0.2 wt% CuO, 0.5 wt% MnO2, and 0.2 wt% SS were beneficial in enhancing the densification and improving the mechanical properties of ATZ without inducing grain coarsening. The ATZ composite samples' relative density, tetragonal phase stability, microstructural evolution, Vickers hardness, and fracture toughness were revealed. The addition of 0.2 wt% CuO was the most beneficial in improving the properties of ATZ at a low sintering temperature of 1250°C since the sample obtained the highest relative density of 97%, Vickers hardness of 13.2GPa and fracture toughness of 6.5 MPa m1/2. In contrast, the undoped ATZ required a high sintering temperature to achieve comparable results to the doped samples. The ANOVA analysis revealed that the CuO-doped ATZ sample exhibited the highest significance and was the most suitable in improving both hardness (H) and fracture toughness (KIc) across all temperature conditions. This study also proved that the microwave sintering technique promotes the densification and mechanical properties of ceramic composites compared to the conventional sintering technique.Graphical abstract

Dislocation-precipitate interactions of a wire arc additive manufactured nickel-aluminum-bronze alloy subjected to uniaxial tensile loading were investigated in this study. A unique multi-scale methodology involving scanning transmission electron microscopy (S/TEM), electron back scatter diffraction (EBSD), and electron channeling contrast imaging (ECCI) was designed to uncover individual interactions with several κ-phase particles. A strong accumulation of dislocations along globular κII and lamellar κIII particles were observed during loading. Shearing of small, coherent κIV particles by dislocations was also observed within the matrix. These interactions provide insights into the processing parameters needed to enhance strength and the ductility of these complex microstructures. Graphical abstract

Energy-absorbing materials are widely used as protection for crash mitigation and concussive head impacts reduction. A structural design can significantly enhance energy absorption in different ways, including plastic deformation and bi-stability. Here, 3D-printed energy-absorbing cells of open and capped double frustum structures are characterized via finite element simulations and compressive experiments. The designs demonstrated a buckling instability under compression, achieving 47 times higher specific energy absorption at their critical stress compared with a solid material. For capped structures, strain rate effect on critical stresses is due to air frictional dissipation. The open structures showed beneficial energy hysteresis due to suction in the cyclic tests.Graphical abstract

In the present study, copper vanadate (CuV2O6) was prepared via a simple precipitation route, followed by calcination. The as-prepared electrode material, CuV2O6, was observed to have a surface area of 62 m2 g−1 by the Brunauer–Emmett–Teller analysis. Further, its capacitance behaviour was assessed using cyclic voltammetry, Galvanostatic charge–discharge studies (GCD) and electrochemical impedance spectroscopy. The electroactive CuV2O6 showed a high specific capacitance of 497 F g−1 at 1 Ag−1. Furthermore, long-term cyclic stability of 3000 GCD cycles at 2 Ag−1 with 92.2% of capacitance retention was attained. Hence, CuV2O6 is one of the potential electrode materials for energy storage systems due to its significant properties, such as porous nanostructure and good surface area. Graphical abstract

A mass formation hypothesis was proposed via inverse tracking of the behaviour of electromagnetic waves, which are characterised by both particle and wave properties. This proposed model becomes the contact point that unifies metre, kilogram, and second (MKS)-based units and Ampere (A)-based units into one. Namely, when the mass, which is classically expressed in ‘kg’, is expressed as ‘m kg’, including the range ‘m’ of ‘kg’ to the surrounding area from the perspective of quantum mechanics, classical mechanics and quantum mechanics are matched exactly. This concept was neatly proved through comparison with Maxwell’s and Planck’s dimensional analyses.Graphical abstractSchematic diagram of concept that force can be generated within certain range outside of mass from electric and magnetic fields that is perpendicular to each other. At this point, direction and magnitude of force outside of mass occur as Lorentz force according to direction and magnitude of perpendicular electric and magnetic fields.

Direct ink writing (DIW) has emerged as a promising manufacturing technique owing to its precise spatial, temporal, and controlled multi-material deposition capabilities, which facilitate the fabrication of well-defined geometrical structures from a broad range of materials. As an alternative to costly chemically tailored DIW functional inks, herein, we present a detailed study of well-known inexpensive, commercially available polymeric thermoset elastomers as potential inks for DIW 3D printing. Chemical compositional and rheological characterizations were performed to compare three commercial acrylic elastomer inks, while printability and various performance properties of the corresponding 3D-printed structures were evaluated.Graphical abstract

We proposed a gradient phononic crystal-Helmholtz cavity structure for simultaneous noise and vibration reduction. By simplifying the structure into a typical Helmholtz cavity and a phononic crystal, we derived the resonance frequency of this structure. Next, we use COMSOL software to calculate the transmission loss and transmissibility. Results of our analysis confirmed that the structure can successfully simultaneous reduce noise and vibration within 2500 Hz, and the range of the reduction frequency is close to 500 Hz. We also show different structures to realize the adjustability of the band gap and improve the practical of noise and vibration reduction.Graphical abstractThis is the simulation diagram of phononic crystal-Helmholtz cavities. From the perspective of multiple physical fields, vibration reduction belongs to solid mechanics fields, while noise reduction belongs to pressure acoustics fields. In our paper, we both studied these two fields, the results show that this structure can simultaneous reduce noise and vibration within 2500 Hz, and the range of the reduction frequency is close to 500 Hz. In addition, the relationship between reduction frequency and the change of gradient is further studied. Results show that the frequency of the bandgap decreases with the number of unit cell increased. The center frequency of the bandgap decreases from 2000 to 1400 Hz, and it becomes stable at about 1400 Hz eventually.