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Short carbon fiber-reinforced Polyamide 12 composite materials were prepared and used as filaments for additive manufacturing (AM) of structures using the Fused Filament Fabrication (FFF) method. The effect of carbon fibers concentration and type, infill pattern and environmental temperatures on mechanical properties of the printed test samples were investigated. The measured tensile modulus of the printed composite ranged from 1.4 to 8.8 GPa, an increase of up to 6.3 times the value of the neat printed polymer. The tensile strength ranged from 40 to 90 MPa, for an increase of up to 2.15 times. Optimization of the environmental temperature for improved coalescence of filaments led to a fair increase in values of the tensile modulus and strength, with an improvement up to 1.5 and 2 times, respectively, for the printed samples with pattern orthogonal to the loading directions. Microstructure characterizations were performed for mechanical results interpretations, with the help of a specialized homogenization model. The combination of FFF and carbon fiber-reinforced composite shows high promises for applications in the transportation industry.

The novel reactive methylmethacrylate (MMA) thermoplastic resin (commercially known as Elium® resin) is the first liquid thermoplastic resin which is curable at room temperature. This resin is a competitive solution against traditional epoxy-based composites. In this work, novel non-crimp (NC) glass fabric/MMA resin composites were manufactured using a vacuum infusion process. Cellulose microcrystals (CMCs) were dispersed in the resin to improve the fibre/matrix interface and the composite properties. CMCs were first dispersed in the resin using an ultrasonication process and then the CMC/MMA resin suspension, mixed with a peroxide initiator, was infused into the reinforcing fabric. The amounts of CMCs dispersed in the resin were 0.5%, 1% and 2% (of the weight of the resin). The influence of CMCs on the interlaminar shear strength (interface), flexural properties, abrasive wear and dynamic-mechanical behaviour was thoroughly investigated. From the mechanical characterisation, it was observed that the addition of 1% CMC to the NC glass/MMA resin composites improved the flexural strength, interlaminar shear strength and wear performance by 30.77%, 38.04% and 22.27%, respectively as compared to the neat glass/MMA resin composite. Above this amount of CMC (i.e., 1 wt%), the properties started to degrade as a result of CMC agglomeration.

Different energy densities in Selective Laser Melting produce different metallurgical properties of the product surface, which include adhered powder particles, waviness, porosity, and microstructure. In this research, the corrosion behavior of these structural properties was investigated and compared with heat-treated samples. The size and arrays of α'-martensitic varied significantly due to the effects of different cooling rates and the number of effective thermal cycles caused by different scanning speeds and energy densities. The surface particles experienced different thermal effects that significantly changed their microstructure with each other and with respect to the main surface, which remarkably affected the corrosion properties. The densities, hardness, and tensile properties of the samples were also presented and interpreted their relations with corrosion. These correlations between the metallurgical and corrosion properties of SLM products support biomedical engineers in the further development of bespoke medical devices, especially implants.

Considerable surface roughness, dimensional deviation, and non-uniform microstructure are a few of the characteristics found on thin or micro-scale features fabricated via laser powder bed fusion (LPBF) that yield inferior and/or inconsistent mechanical properties. Femtosecond laser micromachining can aid in fabricating micro-scale parts with ultra-high dimensional precision. In this work, the surface and tensile behavior of microstruts of 500 μm nominal diameter micromachined with Gaussian laser pulses of 100 f s duration are characterized. Roughness parameters such as R a = 0.9 ± 0.2 μm and R z = 3.4 ± 1.3 μm are achieved on the micromachined faces. Surface-associated grains are successfully ablated with negligible microstructural damage to the microstruts. As a result, the average uniform strain under quasi-static tensile loading is measured as 0 . 54 ± 0 . 02 compared to 0 . 42 ± 0 . 01 for the as-built microstruts. Uniform and non-uniform deformation strain portions are separated analytically and characterized primarily via in-situ imaging. Progressive degradation of the surface and dimensional variance is observed on the micromachined test specimens. Post necking initiation, ablation-associated asperities on the micromachined surfaces evolve into notches, leading to tensile failure.

Designing a suitable scaffold matching the mechanical properties of natural bones to optimize the bone regeneration is required in bone tissue engineering. The present work developed a single-parameter design method for the octet truss topological scaffold to achieve the accurate prediction and flexible adjustment of its Young’s modulus and strength. A theoretical model that formulated the normalized Young’s modulus and normalized yield strength of the octet truss scaffold by the single parameter (d/O) was proposed and further validated by uniaxial compression tests and FEA simulations. On the basis of the proposed model, the Young's modulus and yield strength of the octet truss scaffold made of different polymers with different d/O were mapped, and the ranges of suitable d/O that match the different natural cancellous bones were suggested. The results showed that the design method could accurately predict the porosity, specific area, normalized Young’s modulus and normalized yield strength, and adjust the mechanical properties of the scaffold in a wide range. The present work can be used for the design of scaffolds and the selection of constituent materials to obtain a suitable scaffold with desired mechanical properties, and has application prospects in the fields of bone tissue engineering and regenerative medicine.

With the development of electronic technologies, electronic devices become smaller, while their power density increases dramatically. The resulting excessive heat requires excellent heat dissipation to ensure great performance of the devices. A good thermal interface material (TIM), with excellent bulk thermal conductivity and proper elastic modulus, which can fill the gap between contact surfaces, is of great importance to improve overall performance of thermal management in the electronic devices. Carbon-based materials, such as carbon nanotubes (CNTs) and graphene (Gr), have attracted great attentions, due to their intrinsic high thermal conductivity. In this paper, carbon-based TIMs are reviewed, as well as the thermal conducting mechanisms and techniques to measure thermal properties for materials. The unique three-dimensional network of 3D-Gr provides not only high thermal conductivity, but also excellent mechanical properties, which makes it more competitive as TIM than CNTs and Gr. Furthermore, there is currently no universal characterization techniques, which are suitable to measure thermal properties of all TIMs. Hence, special attention must be paid to select a proper technique based on the measuring principle, in order to obtain accurate results. An outlook of the future challenges of the thermal interface materials is proposed at the end of the paper.

The drying shrinkage of different sedimentary rocks used as aggregates for concrete, mainly sandstone, is evaluated on the basis of petrological characterization and water vapor sorption. The drying shrinkage of aggregates is dependent on their alteration and metamorphic types, and is especially influenced by the types and contents of their constituent minerals and pore spaces between the crystals. There was a positive correlation between drying shrinkage of aggregates and water vapor desorption. When the volume of pores 4–20 nm in diameter was reduced, drying shrinkage and water vapor sorption were drastically reduced. In the case of sandstone aggregates, drying shrinkage of the aggregate is large in the early stage of alteration while it decreases with the progress of alteration and metamorphism processes. The presence of secondary type-A muscovite indicates a transitional stage between these processes, which is an important petrological feature in evaluating aggregate shrinkage. These results clearly show that differences in geothermal gradient and compression intensity from the time of deposition to the present manifested as the alteration and metamorphic types, with divergent pore distributions. The drying shrinkage and the water vapor sorption of aggregates reflect these petrological characteristics and resultant pore distributions.

As innovative nanostructured catalysts, palladium nanoparticles supported on carbon-coated zinc oxide nanowires (PdNPs/C&ZnO-NWs) are widely applied in industrial thermal catalysis, and therefore the real-time insights into their thermal stability and microstructural reconstruction at thermal reaction conditions will greatly extend our knowledge of their physicochemical properties and provide valuable guidance for the applications and designs of future nanocatalysts. The in-situ transmission electron microscopy (TEM) studies revealed the high-temperature resistance to PdNPs aggregations with aids of carbon-coated low-dimensional nanostructures C&ZnO-NWs and elucidated ripening dynamics of PdNPs and the surface reconstruction of C&ZnO-NWs. The operando analysis of PdNPs/C&ZnO-NWs was executed in real-time under working-temperature situations. The aggregations of PdNPs were not observed until reaching a high working temperature of 300 °C and carbon-coated layers could functionally prevent PdNPs from sintering even when ZnO-NWs experienced melting at 500 °C. The time-lapsed TEM investigation proved that the ripening dynamics and time-dependent revolution of PdNPs size are in accordance with the Ostwald ripening process. The subsequent atomic-scale observation revealed the surface reconstruction of ZnO-NWs in the form of ZnO encapsulation over PdNPs and carbon-coated layers during the thermal process, which showed the microscopic evidence of potential deactivation of ZnO-NW-based nanocatalysts in thermal reactions.

Additive manufacturing of hard-to-weld nickel-based superalloys leads to the formation of elongated columnar grain structures and hot cracks along the build direction. Changing the scanning strategy during selective laser melting (SLM) without changing alloy composition is a promising method for the inhibition of hot cracking by grain refinement. In this work, the effect of grain structure on the cracking inhibition behaviour of hard-to-weld Inconel 738 alloy fabricated by SLM with different scanning strategies (rotation of 0°, 90° and 67° between layers, respectively) was investigated. Nearly crack-free, local equiaxed microstructures and an excellent combination of strength and ductility were obtained by rotation of 67° for the SLM-built Inconel 738 alloy due to bimodal grain structure with local equiaxed grains and columnar grains. The local equiaxed grains are attributed to dynamic recrystallization and give rise to thermal stress relaxation. Meanwhile, the aspect ratio of columnar grains is related to thermal gradient variation. In addition, the inhibition of initiation and propagation of cracks is attributed to grain refinement and reduced residual stress. This work demonstrates the feasibility of grain refinement by changing the scanning strategy and improved suppression of cracks in a hard-to-weld superalloy without changing the alloy composition.

A snap-fit method has been designed to establish octet-truss lattice for which the through-thickness direction coincides with structure’s stiffest (crystallographic) direction. Sheet Ti-6Al-4V alloy of a single thickness was used as the starting material for the assembly of lattices which were subsequently brazed in vacuum to bond the nodes. Ambient temperature uniaxial compressive responses of the manufactured lattices have been investigated quasi-statically as a function of the lattice relative density, and are shown to be consistent with micromechanics predictions and finite element simulations. Analytical study reveals anisotropic-shaped biaxial failure loci in principal stress space, which expand anisotropically with an increasing relative density, and demonstrate greater structural strengths under tensile-tensile and compressive-compressive loading states. An assessment of structural efficiency has shown that the present snap-fit route is superior to our previously reported methodology in acquiring mechanically robust lattice performance for applications where maximum rigidity of octet-truss structure is sought. The present work has relaxed the plausible assumption that truss-plane-orthogonality relation must be satisfied for a specific topology to realize its snap-fit construction; incremental types of topology are thus feasible for snap-fit production characterized by versatility in material selection, cost-effective, and scale-up production capability.

An ideal scaffold should have good biocompatibility and osteogenic differentiation properties and provide interconnected porous networks for cell penetration and nutrient and waste transportation. To improve the biological activity of hydrogels, with nano-β-tricalcium phosphate (TCP) as a model, we successfully designed β-TCP nanoparticle/hydrogel encapsulated scaffolds, which improved the osteogenic differentiation ability of bone marrow mesenchymal stem cells (BMSCs) and focused on the osteogenic differentiation mechanism of the β-TCP nanoparticle-mediated microenvironment and phosphorus. Results showed that β-TCP nanoparticles affected phosphorylated ERK1/2 and BMP-2 signalling molecules in BMSCs through ATP metabolism. Addition of an ATP inhibitor (NEM) and SLC20a1 inhibitor (Foscarnet), significantly inhibited expression of phosphorylated ERK1/2 and BMP-2. This study also provides an understanding of the positive role of β-TCP nanoparticles and β-TCP nanoparticle/hydrogel-encapsulated scaffolds in the bone repair field.

Gaining insight into the many agents that determine the underlying material microstructure is essential to engineer new and efficient solutions. Tool steels resistant to abrasive wear are particularly interesting because it is possible to tailor their macroscopic properties by adjusting some of the primary carbide phase features: micromechanical properties, volume fraction, size, and shape. For many popular ledeburitic cold-work and high-speed tool steel alloys, there is a generally good understanding of the effects of the HIP temperature, pressure, and holding time on these traits. Nevertheless, there is still no thorough investigation on the influence of powder size distribution on the primary carbide phase. To that end, we employ in this work novel microstructural characterization methods that shed light on the nature and extent of its influence. We show that powder size has an enduring effect on primary carbide geometric features associated with the solidification process during powder atomization. This work contributes significant process-structure links, which uncover new opportunities for microstructural design.

We report the energy absorption and piezoresistive self-sensing performance of 3D printed discontinuous carbon fiber (CF)-reinforced polyetheretherketone (PEEK) cellular composites. Experiments conducted on three different 2D lattices with hexagonal, chiral and re-entrant topologies of the same relative density (33%) and CF loading (30 wt%) reveal that the CF/PEEK hexagonal lattice (HL), due its relatively brittle response, shows about 40% and 9% decrease in specific energy absorption (SEA) under in-plane and out-of-plane compression, respectively, compared with PEEK HL. While the collapse response of PEEK HL is nearly insensitive to the strain-rate over 43 ≤ e ≤ 106 s−1, we observe a twenty-fold increase in peak stress and a five-fold increase in SEA under in-plane impact loading over the same range of strain-rates for the CF/PEEK HL. The CF/PEEK lattices exhibit pronounced piezoresistive response under both in-plane and out-of-plane compression with maximum sensitivity of 3.1 and 5.2, respectively, for the re-entrant lattice, offering insight into the damage-state. Higher damage sensitivity indicates faster percolation of new contacts due to folds forming between the cell walls within the lattice under compression. The energy-absorbing and strain- and damage-sensing nature of 3D printed CF/PEEK lattices demonstrated here offers insight into the design of lightweight, high-performance multifunctional lattices.

Broadband photodetectors have attracted substantial attention in recent years. The ternary chalcogenide Ta2NiSe5 is a layered material with a direct narrow-band gap (Eg ~ 0.33 eV) which possesses greatly potential to broadband photodetectors. Here, high-quality bulk Ta2NiSe5 was synthesized by Chemical Vapor Transport (CVT) method. We demonstrate a photodetector based on exfoliated Ta2NiSe5 nanoflake, which exhibits a broadband photo-response from 405 nm to 4300 nm. Meanwhile, its main characteristics are superior to other typical 2D materials: high responsivity ~198.1 A W−1 at 1350 nm and ultrafast response time of ~27.4 µs. Long-time photocurrent reproducibility shows that the photodetector has excellent stability under atmosphere. Furthermore, the scanning photocurrent mapping reveals the photoconductive mechanism of Ta2NiSe5 photodetector. In addition, the anisotropic ratio of the photocurrent is ~1.46. The broadband photodetection, high responsivity, anisotropic and environmental stability achieved simultaneously in Ta2NiSe5 photodetector, which are promising for neotype electronics and optoelectronics field.

Mechanical performance is crucial for lattice structures used in orthopedic applications because they should simultaneously possess high strength and high porosity. Although the additively manufactured Ti-6Al-4 V functionally graded porous structure (FGPS) has proven to be the most promising material owing to its good mechanical performance, the impact of porosity gradient pattern on their mechanical performance has scarcely been investigated. In this study, FGPSs with varied porosity gradient pattern and same overall porosity were designed by triply periodic minimal surface and fabricated by laser powder bed fusion (L-PBF), and their structural and mechanical properties were analyzed. A semi-empirical equation was derived to predict the mechanical properties of FGPSs. Hence, we discovered that the lattice with solid core exhibited the best mechanical performance among all FGPS designs. X-ray microscopy (XRM) analysis revealed a strong relationship between the internal micro-porosity of the L-PBF-fabricated samples and the dimensions of the manufactured components, further proving the rationale of the lattice with solid core design. In situ compression tests under XRM visualized the different failure mechanisms in the porous and dense portion of the lattice with solid core. The strengthening mechanism of the lattice with solid core was further revealed by finite element analysis.

Heat assisted-forming processes are essential for Ti6Al4V sheet metal forming due to the poor formability of this alloy at room temperature. Although there exist works on the stress-strain response at high temperature, there is a lack of data in the literature on the yield criteria. The present paper presents an efficient experimental methodology to determine significant stress states at high temperature. Both plane strain data and compressive anisotropy values at high temperature allowed obtaining a more complete definition of the mechanical behavior of the Ti6Al4V, being the novel contribution of this research. Yield loci up to 900 °C were built according to different yield criteria that are fitted to the experimental data. Thus, Barlat1989 and CPB2006 were selected as the most suitable yield criteria to predict Ti6Al4V behavior. These criteria were extended to contemplate the anisotropy evolution under a wide range of working conditions. The formulated extended criteria for the entire range of conditions were close to the equivalent traditional ones applied to only a particular condition, which demonstrates the advanced made in the comprehensive modeling of Ti6Al4V alloy for all conditions applied in forming industries.

The in-situ formation of silver nanoparticles (AgNPs) via dopamine-reduction of Ag+ has been widely utilized for titanium implants to introduce antibacterial properties. In previous studies, the preparation of AgNPs has focused on controlling the feeding concentrations, while the pH of the reaction solution was ignored. Herein, we systematically determined the influence of various pH (4, 7, 10) and Ag+ concentrations (0.01, 0.1 mg/mL) on the AgNPs formation, followed by the evaluation of the antibacterial properties in vitro and in vivo. The results revealed that an alkaline environment was favourable for AgNP formation and resulted in more particles. Although the AgNPs bearing Ti had lower biocompatibilities, it was significantly improved after 7 days of mineralization in simulated body fluid. The outstanding antibacterial property of the AgNPs was well maintained after one day and seven days of implantation. Moreover, 3D micro-CT modelling showed that the pH 10/0.1 group exhibited remarkable osteogenesis, which may be due to their strong antibacterial properties and ability to promote mineralization. Therefore, we have demonstrated that the solution pH was as important as the feeding Ag+ concentration in determining AgNP formation, and it has paved the way for developing various AgNP-loaded surfaces that could meet different antibacterial needs.

Additive Manufacturing (AM) technologies such as Laser-Based Powder Bed Fusion (LB-PBF) enables the manufacturing of high efficiency lattice structures. However, the LB-PBF processes inherently generate local geometric effects. The practical implications of these geometric effects on structural performance is of critical importance to effective AM design; however, these effects are poorly understood. In response to this uncertainty, this research compares predictive and experimental data for the structural response of LB-PBF lattice strut elements subject to compressive loading; this comparison is made for LB-PBF manufactured Ti-6Al-4V LB-PBF but is generally applicable to all AM systems and materials. This data provides insight into the influence of geometric design parameters, including: node and strut diameter, strut length, and manufacturing inclination angle. The effect of these geometric parameters on the associated critical buckling load, and the accuracy of predictive failure models is quantified. Furthermore, the eccentricity ratio, a classical measure of column efficiency widely used in civil engineering design, is applied for the first-time as a systematic metric to characterise the structural efficiency of as-manufactured AM strut element.

The paper describes Electromagnetic Ring Expansion Tests (ERET) performed on Laser Melting Powder Bed Fusion (LPBF) Inconel 718 stress relieved test pieces, to establish the effect of a randomly dispersed spherically voided microstructure on tensile ductility, fracture, and fragmentation at high strain rate (10-3 < e < 104 s-1). An empirical model to predict porosity type and growth rates as a function of laser energy density was established, to select the LPBF process parameters to fabricate test pieces under stable conduction and keyhole melting. The size, shape, distribution of macro and keyhole pores in the test pieces obtained for ERET testing were characterised. At high strain rate the number of ring fragments for the highest porosity doubled, accompanied by a reduction in true strain at maximum uniform elongation and fracture strain. The trend for reducing fracture strain with increasing porosity at high strain rate was described by a decaying power law. Overall, there was a significant positive strain rate effect on tensile ductility at lower porosities attributed strain rate hardening (Hart, 1967) [1]. Fracture surfaces containing the highest porosity identified four different void coalescence mechanisms that helped explain the influence of larger pores on the stress state in the alloy. The AM of IN718 and tensile testing was funded by the UoD, College of Science and Engineering Research Excellence Framework (REF) funding for the Director of IISE (P. Wood) and AM Researcher (U. Gunputh). The support of G. Williams for IN718 sample preparation and M. Pawlik for tensile testing is acknowledged. A. Rusinek acknowledges the program UC3M-Santander Chair of Excellence in additive manufacturing. The expanding ring tests investigations were funded by the Polish Ministry of Science and Higher Education, Centre for Research and Development under research grant No. TECHMATSTRATEG2/410049/12/NCBR/2019.

In situ synchrotron X-ray computed micro-tomography and digital volume correlation (DVC) were utilised to understand the failure mechanisms at room temperature and 1050 °C of two Nextel™720/alumina oxide-oxide ceramic-matrix composites (CMCs), termed materials A and B, sintered respectively at 1200 °C and ~1250 °C. At both test temperatures, three-point-bending strengths were ~55–58 MPa for material A and ~94–100 MPa for material B. Damage was associated with three primary types of cracking modes: interfacial delamination, inclined cracks within fibre tows, opening of existing matrix shrinkage cracks. Material A exhibited higher shrinkage cracking, whereas material B displayed more pronounced diagonal matrix microcracking. At 1050 °C, both systems showed less microcracking but more pronounced delamination. Such damage characteristics were rationalised in terms of the corresponding 3D DVC displacement/strain fields. Specifically, global DVC was utilised and maximum principal strain locations prior to failure, which varied from 0.005 to 0.01, correlated well to the fracture initiation sites. Further, abrupt positive to negative transitions of shear strain components were observed and were attributed to the different bonding strengths between 0°/90° fibres and the matrix. The current study demonstrates that in situ high-temperature tomography/DVC is a powerful method for studying the deformation and fracture of oxide-oxide CMCs.

In this paper we report the morphology and the microstructural properties of thick [1 1 1]-oriented 3C-SiC films epitaxially grown on T-shaped Si micropillars. This compliant substrate was designed to release the stress developed in 3C-SiC grown on Si, due to the lattice mismatch and the different thermal expansion coefficients between 3C-SiC and Si. In this way it was possible to have 3C-SiC films as thick as 10 and 16 μm, with small bowing and no cracks. Our study relies on the use of an Electron Microscopy approach and elucidates the structure of the crystallographic defects across the 3C-SiC film, such as stacking faults (SFs), nano-twins and grain boundaries (GBs). After examination of the morphological and structural characteristics of the Si micropillar array, we analyzed the crystallographic properties of the thin 3C-SiC deposit on the Si micropillar sidewalls, since it may have an impact on the upper film. To assess the crystal quality of the 3C-SiC film, we quantified the SF density at the 3C-SiC surface, even estimating semi-quantitatively the depletion of SFs at much larger thickness. Hence, we analyzed the regions where 3C-SiC microcrystals grown on neighboring Si micropillars coalesce and form a continuous layer. We found that the coalescence between adjacent 3C-SiC microcrystals produces twinned regions, which terminate with the formation of GBs. We noticed that SFs may annihilate at the GBs, leading to the SF reduction across the 3C-SiC film. Finally, we observed the closure of the GBs inside the 3C-SiC film, thus improving the crystal quality of its surface. This work endorses the use of Si micropillars as compliant substrate to grow thick [1 1 1]-oriented 3C-SiC films with good crystal quality and is preliminary to the exploitation of 3C-SiC for high performing microelectronic devices.

This paper presents a comprehensive study of the microstructure-property relationships in Ta and stainless or carbon steel composites, fabricated by explosive welding using Cu interlayer. Employing scanning (SEM) and transmission (TEM) electron microscopy and X-ray synchrotron diffraction, a complex microstructure of interfacial layers was examined. Particular attention was placed on the description of the phase transformation mechanisms in the reaction regions, and the competition between the strain-hardening and softening processes in parent sheets. SEM and TEM analyses showed that Cu and Ta nanoparticles, and small dendrites, dominated the reaction regions near the Ta/Cu interfaces, whereas the nano-grained phases having more complex chemical compositions were identified near the Cu/steel interfaces. SEM orientation mapping revealed that the interfacial layers of the parent sheets underwent severe plastic deformation as a result of dislocation slip, twinning, and shear banding. Such heavily deformed areas can easily undergo recovery and recrystallization already during clad processing. In consistence with these findings, the micro-hardness values of the welded sheets increased as the joining interface approached, except for the layers directly adhering to large reaction regions, where a decrease in micro-hardness was observed. However, the solidified melt regions were essentially softer than the strain-hardened layers of both steels. Based on experimental results a new explanation for the reaction region formation was proposed and a significant modification of the description of the interfacial microstructure of parent sheets was done. Finally, the effect of microstructural changes on the clads properties was discussed.

Low-free-energy surfaces have attracted an intense academic and industrial interest over the last decade. A reduction of the surface free energy (SFE) has been found to enhance self-cleaning, hydrophobic, and non-fouling properties of surfaces, which are highly desirable in many industrial applications. However, tuning the surface chemistry and topography to achieve tailored low free energy surfaces has been found extremely challenging. In this work, we first show that an accurate refinement of the atmospheric plasma technique guarantees a polymeric coating near to the super-hydrophobic regime. Second, by coupling modelling and experimental measurements we suggest a reliable workflow for the surface characterization and smart design. Specifically, the case study proposed in this contest is capable of quantitatively distinguishing the contribution of a Perfluoro Decyl Acrylate (PFDA) coating, and hence decoupling the role of surface chemistry and roughness, in the reduction of the surface free energy of a bare silicon sample. Beyond the specific case study, our results also emphasize that a synergistic combination of models and experiments can unveil the optimal pathway for designing low-free-energy surfaces.

Catalysis, a driving force of the chemical industry is increasingly being influenced by additive manufacturing. The link between them is based on the need to intensify catalytic processes in order to make them more efficient and sustainable. Additive manufacturing can satisfy such a need, generating devices with an advanced design, easy production, and great adaptation, in addition to their catalytic functionality. The exponential growth of examples reported on the application of 3D-printing in catalysis has led to the need to compile and analyse these cases and thus establish, through this review, the most in-depth analysis done to date. The manuscript includes a brief background of the history of additive manufacturing and the classification of the different printing techniques. Subsequently, it identifies the intensification of processes, among other aspects, as the key for understanding the union of additive manufacturing and catalysis. Then, it explores in detail how such a combination occurs, establishing the most comprehensive classification to date between the two large groups of printable devices with catalytic properties. Finally, a series of perspectives are proposed in which the most probable courses of new advances in this field of research are identified.

Graphene-based hybrid coatings have received considerable research interest in realizing the anti-corrosion application due to their high strength and impermeability. Graphene morphology is an important factor in determining the behaviors of composites. However, there have been few reports on the application of GO nanoscrolls in anti-corrosion coatings. Here, we obtained a hybrid siloxane-epoxy (SE) coating reinforced with worm-like graphene oxide (FGO) nanoscrolls for the protection of AA2024 alloy. GO sheets were firstly functionalized with tetraethoxysilane (TEOS) through a sol–gel method and incorporated into the SE resin via a wet transfer method. Chemical, structure and morphological analyses revealed that FGO sheets with active -Si-OH groups, increased surface wrinkles and decreased layers were obtained. During the transfer process, Si-OH guided the transformation of FGO into the tubular structure. Ultrasonication provided the required activation for scrolling and the vacuum cavity offered the deformation space. FGO sheets resulted in better dispersion and interfacial interaction. The positive effect of the characteristic structure on the mechanical and anti-corrosion properties of the coating outweighed the negative effect of the laminated stacking GO. SE/FGO coatings were characterized by high cross-linking density, toughness, flexibility, easy-produced and eco-friendly. This work provides a new strategy for developing high-performance graphene-based nano coatings.

Propellants are the main energy source in the internal ballistic process. The use of 3D printing has promised to produce propellants with complex geometries. However, due to the degraded energy properties of propellants using an inert binder, there is a critical need to develop a printable energetic resin. In this paper, a novel energetic acrylate-terminated poly–3–nitratomethyl–3–methyloxetane (APNIMMO) oligomer was prepared and characterized. The performance of a new composite propellant composed of APNIMMO and CL-20 (Hexanitrohexaazaisowurtzitane Dodecane) was also demonstrated. The new energetic printable resin and its composites are suitable for stereolithography (SLA) 3D printing, offering not only an improved thermodynamic energy, but also a substantially improved burn rate. Compared with the inert binder, the energetic binder offers the possibility to improve the thermodynamic energy by 15% and the burn rate at 100 MPa by 480% for 3D printed propellants.

As a novel family of 2D materials, MXenes are supposed to play a vital role in optoelectronic devices and systems due to their high conductivity, good optical properties, and favorable compatibility with water and organic solvents. However, the application of MXenes in highly sensitive photodetection is far scarcely investigated. Here, we demonstrate high-quality Ti3C2Tx/GaAs Schottky junction by simply dripping Ti3C2Tx MXene solution on a pre-patterned GaAs substrate. Owing to the wide absorption of MXene and the good quality junction, the self-driven Ti3C2Tx/GaAs Schottky junction photodetector with an impressive performance is realized. The assembled photodetector exhibits a high sensitivity over a wide waveband with a good responsivity of ~1.46 A/W, a large specific detectivity of ~1.23 × 1013 Jones, and a high Ilight/Idark ratio of 5.6 × 105. Significantly, the photodetector is capable of sensing infrared light signal up to 980 nm which exceeds the absorption edge of GaAs (874 nm) due to the generation of hot electrons in Ti3C2Tx MXene film. Given the superior device performance along with a simple and facile fabrication method, the Ti3C2Tx/GaAs Schottky junction photodetector may find the great potential in high performance broadband, self-driven photodetection applications.

The natural nanoclays and basalt fibers are attracting a considerable amount of interest due to their outstanding properties. Halloysite nanotubes (HNTs) incorporated basalt fiber reinforced polymers (BFRPs) exhibit promising potential applications in marine industries, such as offshore oil platforms and pipelines, due to their high mechanical strength and robust chemical durability. However, their damping capability, which is of great importance for large structural component applications, has not been yet thoroughly investigated. The main goal of this study is to investigate the damping property of nanoclays incorporated BFRPs, by combining the experimental patterns with the respective computational insights. Multiple-structured nanoclays were successfully synthesized by following various experimental approaches. The “stick-slip” mechanical model was implemented in order to elaborate on the energy dissipation issue, due to the development of interfacial frictional slip, whereas the experimental outcome was compared with the respective computational results in order to test the validity of our theoretical approach. Along these lines, the dynamic properties obtained by experimental analysis divulged a fair degree of agreement with the computational results. The fabrication of composites by incorporating HNTs with moderate aspect-ratio value and interfacial bonding can be considered as a quite promising solution in improving the energy dissipation performance.

Additive manufacturing (AM) technologies offer novel opportunities for processing difficult to cast refractory materials. Electron beam melting (EBM) AM is particularly attractive as the rapidly moving electron beam can be utilized to heat the powder bed which mitigates against some process induced cracking mechanisms. A great deal of prior work has been done to investigate laser based processing of molybdenum but little EBM focused work currently exists. In this work we investigate EBM processed molybdenum and observe sharp 0 0 1 , 1 1 1 , and mixed 0 0 1 & 1 1 1 crystallographic fibers in the build direction. The apparent preference between these build direction fibers is dependent on the imposed energy density and this is likely explained by the weld pool shape. Detailed microscopy reveals that the observed columnar grains consist of much finer equiaxed low angle boundary subgrains suggesting large process induced stresses leading to appreciable plastic deformation. The implications resulting from this work are that molybdenum may be processed crack-free via EBM AM and that fiber-switching may be controlled, and exploited, towards fabricating components with optimized performance.

Rheumatoid arthritis (RA) is one of the most prevalent inflammatory joint disorders. Early diagnosis, accurate staging, and imaging guided treatment response of RA remain crucial clinical significances for improving treatment outcomes. In this study, we introduced endogenous melanin nanoparticles (MNPs) conjugated with Cyclic Arg-Gly-Asp (RGD) peptide (MNP-PEG-RGD) as a contrast agent for accurate photoacoustic imaging (PAI) of RA diagnosis. It was observed that the prepared nanoprobes had favorable PA sensitivity, photostability and biocompatibility. In vivo studies using RA mouse model revealed that this nanoprobe could target αvβ3 actively at 1 h post-injection, while the signal was remarkably increased in the arthritic joint which could earlier diagnose RA than conventional imaging system. It was of crucial importance to staging RA by PAI with significant difference in nanoprobes accumulation. Furthermore, we tracked the therapeutic efficacy of etanercept in RA treatment by PAI. The observed advancement of arthritis on the PAI was confirmed by histological and immunohistochemical analysis. In conclusion, this study shed light on the development of innovative multifunctional theranostic nanoplatform for both RA monitoring and treatment with a promising future in clinical translation.

Localised fluctuation in residual stress distribution for direct energy deposited 316L stainless steel thin plate was revealed through high-energy synchrotron X-ray diffraction. The macroscopic residual stress levels are changed steadily across the article according to the characteristic cooling rates, as implied by the measured dendrite arm lengths. Localised fluctuations of residual stress in the length scale, between 500 and 600 µm, coincides well with the morphological variations of the solidification microstructure that formed during direct energy deposition. Computations indicate a greater propensity for related mesoscopic thermal gradient fluctuations along the solidification front of the moving melt pool. Novel perspectives on residual stress across multiple length-scales and its relevance to the formation of solidification microstructure in metal additive manufacturing is analysed by considering the experimental results.

Natural bone substituting materials derived from living organisms have been utilized to treat bone malfunctioning. However, limited sources and immune issues have led to the use of artificial scaffolds consisting of biocompatible materials. Additionally, a functionally graded porous structure has been acknowledged as an alternative to overcome reduced mechanical properties by pores and alleviate stress shielding effect. In this study, a two-body combination achieved through a densification process, in which recombinant human bone morphogenetic protein-2 (rhBMP-2) and tetracycline hydrochloride (TCH) can be simultaneously released for efficient bone regeneration, is proposed. Biomimetic titanium scaffolds (BTSs), which possess significantly different pore characteristics, are successfully fabricated. The mechanical properties of these parts are proven to be applicable as bone substitutes. The release of rhBMP-2 and TCH from the BTSs is prolonged compared to that of homogenous porous titanium scaffolds (PTSs). The prolonged release of rhBMP-2 from the BTS results in a sustained degree of pre-osteoblast differentiation. The antimicrobial properties of these scaffolds are verified using pathogens. Furthermore, various structures exhibiting different pore characteristics are obtained by mechanical interlocking between components. This study demonstrates that the novel assembled platform as customizable Lego-like building blocks, with its tunable mechanical and multi-biomolecule release properties, is promising for bone tissue engineering.

Bimetallic structures processed via laser-based additive manufacturing (AM) efficiently combine multiple materials in single components, which are difficult to achieve using traditional methods. However, limited understanding exists on how processing parameters influence the resulting microstructures and thermal profiles of base material during processing, affecting component performance. To this end, we present a combined numerical and experimental study on the effects of input laser power and scanning speed on the heat-affected-zone (HAZ) and fusion-zone (FZ) of a tantalum-titanium bimetallic structure, two compatible materials that are challenging to process traditionally and are desirable in a bimetallic system. We demonstrate that a wide array of track characteristics can be achieved by varying the laser power and scanning speed. The HAZ and FZ microstructures' width and depth within the underlying Ti6Al4V substrate can be estimated within 6–19% of the experimentally determined values using a 3D transient-thermal finite element analysis (FEA) model, with the most significant errors occurring at low scanning speeds. Adjusting the absorptivity input to the model improves prediction to within 1–11% difference of the HAZ/FZ dimensions and corresponding temperatures relative to the experimental dimensions across a broad range of laser power and scanning speeds. Our results indicate that the underlying temperatures achieved in bimetallic components can be predicted accurately using a detailed FEA approach, aiding larger-scale approaches towards improved process modeling and manufacturing of bimetallic structures using laser-based AM.

Nickel-based alloys are extensively used in a wide range of extreme environments because of their exceptional mechanical properties. The excellent strength of these alloys is derived from the addition of long-range ordered precipitates, introduced by thermal aging. The interactions between the dislocations and LRO precipitates dictate the deformation modes and plastic response in these alloys. While the majority of studies have focused on L12-structured precipitate-strengthened Ni-based alloys, less work has considered the Ni-based alloys containing Pt2Mo-structured, Ni2(Cr,Mo)-typed precipitates. In these alloys, Pt2Mo-structured precipitates enable room-temperature deformation twinning in addition to slip, which increases strain hardenability measured from bulk mechanical testing. Although previous geometric-based model suggested that deformation twinning is favored over slip, the factors that influence the activation between twinning versus slip have not been thoroughly explored in this class of Ni-based alloys. In this work, molecular dynamics examined the possible types of dislocation and Pt2Mo-structured precipitate interactions at low temperature. Combined with in situ micromechanical testing, the role of resolved shear stresses on dislocation partials were shown to directly influence the activation of slip versus twinning. Additionally, using an energy-based approach, molecular dynamics results demonstrated a novel twin formation process, caused by the dislocation interaction with the Pt2Mo-structured precipitates.

The additively manufactured Ti-6Al-4V part suffers from undesirable α ′ phase, which leads to a decrease of its plasticity. In this research, density-based constituent phase simulation method is applied to investigate the phase transformation of Ti-6Al-4V during wire laser additive manufacturing (WLAM). Single-layer and five-layer WLAM experiments are conducted to validate the accuracy of the simulation. The simulation results agree with the experimental results. By in-situ investigating the phase transformation during cooling, it is found that there exist four stages for β → α / α ′ , which are (I) β → α gb / α C , (II) β → α B , (III) β → α ′ and (IV) β → α B and α ′ → α B + β . Increasing the temperature and decreasing the cooling rate help in narrowing or even eliminating the β → α ′ stage, which finally leads to the decrease of α ′ fraction or even avoid its formation. Compared with the laser power 2500 W case, the laser power 3000 W case gets more transformed α B without increasing α -lath thickness. The simulation shows promising prospects in predicting phase transformation, revealing underlying mechanisms and optimizing processing parameters.

3D printed titanium implants have gained substantial attention in the medical fields of bone tissue and dental implants. Surface modification of titanium implants such as TiO2 nanotubes (TNT) make up for the interaction between the surface of titanium implants and the surrounding tissues by providing nanoporous structures and hydrophilic surfaces. In this study, a 3D printed Cu-bearing Ti6Al4V (TC4) alloy with micro/nano-topographical was employed as material model to explore the role played by Cu2+ and nanostructure in the physical–chemical properties of the material, osteoblast toxicity. The role of Cu2+ and nanostructure on macrophage proliferation, polarization and oxidative stress without and with lipopolysaccharide (LPS) stimulation was also evaluated. Surface characterizations showed TNT significantly increased the roughness and surface hydrophilicity of TC4 alloy. TNT-TC4-5Cu exhibited excellent corrosion properties in the absence and presence of LPS. The in vitro tests with MC3T3-E1 cells demonstrated that the TNT-TC4-5Cu alloys showed the better cytocompatibility. Moreover, TNT-TC4-5Cu alloy can inhibit macrophage polarization and decreased ROS generation without and with LPS stimulation, thereby promoting the biocompatibility. In summary, the TNT-TC4-5Cu alloy promoted the proliferation and adhesion of osteoblasts and inhibited the inflammatory response of macrophages, which has great potential to benefit the future development of orthopedic applications.

Prediction of the phase constitution of the multi-principle elements alloys (MPEAs) with various element numbers is important for alloy design and performance optimization. Herein, valence electron density parameter, α , is proposed as an improvement of the valence electron concentration by including the impact of atom volumes. The phase constitution of numerous MPEAs is well predicted by the priori α- Δ H mix (enthalpy of mixing) criterion, evidenced by the distinguishing of FCC single phase, FCC and BCC dual-phase and BCC single phase. The similarity of elements in MPEAs is evaluated by the derivative of α and Δ H mix with respect to atomic percentage, which successfully predicts the phase constitution of CrFeNi with addition of Ti, Zr, Al, Cr, Fe, Ni, Co and Cu. This work provides valuable insights into priori judgement of the phase constitution of MPEAs in the view of the relationship between elements.

The modeling of the deformation and failure process of a cyclotetramethylene tetranitramine modified double-base (HMX-MDB) propellant based on the microstructure is of great importance for its manufacturing process and storage lifetime. In the present work, the debonding, nucleation, and crack propagation in an HMX-MDB propellant were investigated experimentally and numerically. Stress-strain responses and viscoelastic parameters were obtained through uniaxial tensile tests on the HMX-MDB propellant and stress relaxation tests on a nitrocellulose-nitroglycerine (NC-NG) propellant, respectively. A two-dimensional representative volume element (RVE) model was developed based on the molecular dynamics method by embedding HMX particles in the NC-NG matrix. A zero-thickness cohesive element was used to simulate the damage behavior of the matrix and the interface. A piecewise cohesive zone model (PCZM) was established to capture stress-strain responses resulted from the matrix rupture and the debonding process at the particle-matrix interface. The effects of matrix strength and interface strength on the mechanical properties of the HMX-MDB propellant were investigated by PCZM. The different ratio of matrix strength to interface strength revealed three kinds of HMX-MDB propellant’s damage patterns: matrix cracking, matrix cracking followed by particle-matrix interfacial debonding, and particle-matrix interfacial debonding followed by matrix cracking.

Relaxor ferroelectrics are attractive for the high energy storage density. However, the polarization responses of most relaxor ferroelectrics are sensitive to temperature, thus leading to thermal-dependent energy storage properties. In this work, 0.5Bi1/2K1/2TiO3–0.5SrTiO3 (0.5BKT–0.5ST) and 0.95(0.5Bi1/2K1/2TiO3–0.5SrTiO3)–0.05Bi(Zn1/2Ti1/2)O3 (BKT–ST–0.05BZT) ceramics were prepared using the solid-state reaction method. Both compositions showed an average cubic structure, with a relaxor-type dielectric anomaly. The rather low remanent polarization and delayed saturated polarization indicated the formation of the ergodic polar nano regions. Benefitting from the Bi(Zn1/2Ti1/2)O3 modification, the recoverable energy storage density (Wrec) reached 3.07 J/cm3 because of the enhanced polarization and increased bandgap. Meanwhile, BKT–ST–0.05BZT exhibited a high storage efficiency ( η > 88%). When the specimen was heated from 30 °C to 150 °C, Wrec under the maximum electric field Em of 150 kV/cm varied from 1.58 to 1.63 J/cm3 (＜ ±2%).

The exchange of Ca2+ ions in hydroxyapatite (HAp) with Zn2+ ions into Zn-HAp is of interest for applications ranging from bone tissue engineering to the use as a precursor in subsequent ion-exchange reactions. Previous studies, using direct synthesis, showed that ~ 20 mol% Zn2+ ions can be incorporated into HAp, before byproducts are observed. However, this is realized at the cost of a loss in crystallinity and control over crystal size and shape with increasing amounts of Zn2+ ion incorporation. In this work a simple post-synthetic ion-exchange strategy for the formation of Zn-HAp has been investigated. By merely exposing HAp to high concentrations of zinc nitrate in water, up to 22 mol% of the Ca2+ ions can displaced by Zn2+ ions without any measured loss in crystallinity and preservation of crystallite size and shape. It was found that the incorporation of Zn2+ ions destabilizes the HAp crystals resulting in their gradual dissolution and reprecipitation. Consequently, promoting the exchange of Ca2+ with Zn2+ions using increased reaction times, sonication and increased temperature results in an increased dissolution of HAp and precipitation of hopeite crystals, thereby preventing the formation of more zinc rich Zn-HAp.

Electrospun nanofibers have been widely used in various biomedical applications. However, electrospinning methods generally focus on monolithic and coaxial fibers while ignoring Janus fibers. In this study, Janus-structured nanofibers for wound healing were fabricated via uniaxial electrospinning based on the phase separation of polyvinylpyrrolidone and polycaprolactone in solution. To enhance the bioactivity and antibacterial activity of wound dressings based on the Janus nanofibers, Rana chensinensis skin peptides (RCSPs) and silver nanoparticles (Ag-NPs) were successfully loaded into the Janus nanofibers. The Janus nanofibers exhibited a bead-free surface and a characteristic side-by-side interior structure. The thermal properties, wettability, and mechanical properties of the Janus nanofibers were studied. The Janus nanofibers were found to have low cytotoxicity and antibacterial activity and were able to accelerate wound healing, which was typical of re-epithelialization, fibroblast proliferation, and regeneration of capillaries and hair follicles within 14 days. The findings indicate that Janus nanofibers loaded with RCSPs and Ag-NPs are promising wound dressing for skin tissue engineering.

Thermomechanically active shape-programmable elastomer microparticles are very promising for development of particulate composites with unique operational properties, which could be attractive for various applications, e.g., in 3D printing. Liquid crystal elastomers are one of the suitable candidate materials due to their remarkable spontaneous shape change response. Performed rheological and thermomechanical tests demonstrate that shear stress can be used to efficiently manipulate the nematic order-driven morphology of liquid crystal elastomer microparticles (μLCEs). Specifically, by exploiting the soft-elasticity character of the material through manipulation of shear amplitude time profile, the nematic director can be oriented along the flow, which results in alignment of microparticles. Using this method, a suspension of well-aligned, thermomechanically elongated monodomain μLCEs can be created by shear stress-assisted cooling. Although the alignment can be lost in absence of persistent flow, it is restored instantaneously on re-application of the flow. The reason for this is the preservation of particle elongation at room temperature in zero flow. This shape memory can be erased by heating the system to the isotropic phase. Our work represents an important step forward in the development of a new generation of shape-programmable materials, which are potentially suitable for additive manufacturing of artefacts with anisotropic physical properties.

The effects of the electron beam (EB) continuity on the microstructures and mechanical properties of titanium lattice structures with produced by EB additive manufacturing were studied. Continuous line and discontinuous spot scans were applied for the EB continuity. The porous structures produced with the continuous line scans had lower defect densities than those produced with discontinuous spot scans. Most defects of the continuous line scans had spherical morphologies, whereas non-spherical defects formed in the porous structure produced with discontinuous spot scans because of the availability of sufficient heat for melting the powder. The microstructures were composed of an α-titanium matrix, martensitic α′ phases, and elongated FeTi4 phases on the grain boundaries. Furthermore, the atom probe tomography results showed that the FeTi4 phase had a network structure with a diameter of 5 nm after the continuous line scan, which enhanced the compressive strength. The compressive strength and elastic modulus of the porous structures produced with the continuous line scan were more than 400 MPa and 11 GPa, respectively. Despite the high porosity, continuous line scans are preferable for achieving high compressive strengths with low elastic moduli for biomedical devices.

Mechanical properties of polyvinyl alcohol (PVA) are of essential importance to the practical application. Much effort has been done to further improve the properties of PVA by modifiers. However, in-depth insight into the role of the modifiers in the properties of PVA at a molecular level still remains rare. Therefore, the Glass transition temperature (Tg) and mechanical properties of PVA, PVA/graphene oxide (GO) and PVA/TRIS functionalized graphene oxide (Tris-GO) are investigated by molecular dynamics (MD) simulation. The results indicate the volume of PVA, PVA/GO and PVA/Tris-GO regularly varies with temperature. The PVA/Tris-GO show a higher Tg compared to the PVA/GO owing to stronger hydrogen-bonding interactions. The Young’s modulus, Shear modulus and Cauchy pressure of PLA/Tris-GO nanocomposites are enhanced by 50%, 46%, and 40% at 2.5 wt% addition amount of Tris-GO. In addition, the introduction of Tris-GO can significantly reduce the mobility and flexibility of the PVA chains in the PVA/Tris-GO. The binding energy between PVA and Tris-GO is larger than that between PVA and GO, which leads to the improved mechanical properties of the PVA/Tris-GO. These simulation results provide a better understanding of the thermomechanical mechanism of PVA/Tris-GO nanocomposites, and an effective guidance for improving their mechanical properties.

In this paper, we took cold-rolled Al-Cu5.0-Mg0.5-Si0.5 alloy as the research object. The roles of 0.1 wt% in-situ nano-TiC and nano-TiC-TiB2 in solid–liquid and solid-state transformations (solution plus aging precipitation) were systematically investigated and compared. We found that trace in-situ nanoparticles can stimulate the nucleation of α-Al dendrites and hinder their growth, meanwhile serving as the heat storage and heat sustained-release carriers during solid–liquid transformation. In the process of solid-state transformation, recrystallization nucleation is promoted, and grain boundaries are pinned by nanoparticles. Meanwhile, the nucleation of Al2Cu is accelerated, and refined Al2Cu distributes more uniformly. Besides, similarities and differences in the manipulation mechanisms of nano-TiC and nano-TiC-TiB2 during solid–liquid and solid-state transformations were analyzed. The mechanical properties and the responsible strengthening mechanisms were discussed in detail.

In this study, poplar wood flour at various concentrations (1–10 wt%) is incorporated into a methacrylate-based resin via solution blending to fabricate wood-reinforced composites using stereolithography apparatus (SLA) 3D printing. Differential scanning calorimetry (DSC) along with Fourier transform infrared spectroscopy (FTIR) analysis shows the presence of a small amount of residual monomer in the printed samples. For the printed composites, the glass transition temperature (Tg) from dynamic mechanical analysis (DMA) decreases as more wood flour is incorporated, which indicates an increase in free volume occupied by polymer chains. The tensile strength is improved up to 17.3% from 21.1 MPa (no wood flour) to 24.7 MPa (1.0 wt% wood flour). The highest Young’s modulus reaches 323.8 MPa (2.0 wt% wood flour), which is 1.9-fold of that of the sample without wood flour. Moreover, the composites show “stress whitening” with the addition of wood flour during the uniaxial drawing. Morphology analysis of the tested samples show that the formation of microcraze and microvoids likely causing the stress whitening. This is the first study that demonstrates wood flour can be utilized in SLA 3D printed wood plastic composites (WPC) which can reinforce the printed products with a modest loading amount.

This study proposed a scheme based on Machine Learning (ML) models to detect geometric defects of additively manufactured objects. The ML models are trained with synthetic 3D point clouds with defects and then applied to detect defects in actual production. Using synthetic 3D point clouds rather than experimental data could save a huge amount of training time and costs associated with many prints for each design. Besides distance differences of individual points between source and target point clouds, this scheme uses a new concept called “patch” to capture macro-level information about nearby points for ML training and implementation. Numerical comparisons of prediction results on experimental data with different shapes showed that the proposed scheme outperformed the existing Z-difference method in the literature. Five ML methods (Bagging of Trees, Gradient Boosting, Random Forest, K-nearest Neighbors and Linear Supported Vector Machine) were compared under various conditions, such as different point cloud densities and defect sizes. Bagging and Random Forest were found the two best models regarding predictability; and the right patch size was found to be at 20. The proposed ML-based scheme is applicable to in-situ defect detection during additive manufacturing with the aid of a proper 3D data acquisition system.

This study unleashes the potential of nanoporous connected networks as excellent oil reservoirs for reducing friction and wear in Al2O3-Al2O3 tribo-pairs. Alumina were fabricated via slip casting and sintering to generate wide-ranging densifications (70–99.5%) and slid in a reciprocating flat-on-flat configuration. Friction coefficients (FCs) lie between 0.025 and 0.37 which decreased with an increase in normal load (10–220 N), lubricant’s viscosity (19, 289 mPa·s) and sliding frequency (6, 12, 24 Hz). A central finding is that FCs of infused specimens are smaller than those of surface lubricated. Wear rates decreased from 10−5 to

The release of drugs in the brain is a challenge due to the blood–brain barrier, but intranasal administration of hydrogels enables the continuous release and quick targeting of drugs into the brain. The aim of this study was to prepare a genipin/hydroxypropyl-β-cyclodextrin inclusion complex thermosensitive hydrogel system (genipin-THS) and evaluate its antidepressant effects. The genipin-THS was constructed using the cold method and was further optimized based on the results of gelation temperature and in vitro drug release. In the in vivo experiment, the genipin-THS significantly reduced the immobility time of mice displaying behavioral despair, decreased the ptosis score and increased the change in the body temperature of mice induced by reserpine, and improved abnormal levels of neurotransmitters (including 5-hydroxytryptamine and norepinephrine) in brain. In addition, the intranasally administered genipin-THS increased the bioavailability of the drug in the hippocampus, and the fluorescence distribution also showed that the thermosensitive hydrogel continuously released the drug for a longer time. In summary, the intranasally administered genipin-THS improved the bioavailability of genipin in the brain, increased its brain targeting, and further enhanced its antidepressant effects on depressive disorder.

The fabrication of Cu pillars has recently attracted much attention from the microelectronic/communication industry because pillars can act as thermal dissipation devices and electrical interconnections among different packaging levels, providing efficient utilization of space in microelectronic packaging applications. This study was conducted to investigate the fabrication of Cu pillars through a high-speed electrodeposition method and their adhesion to an Ajinomoto build-up film (ABF). The morphological, crystallographic, electrical, and mechanical characteristics of the Cu pillars electroplated with various current densities (j = 2, 5, 7.5, and 10 A/dm2) were systematically investigated through a scanning electron microscope (SEM) combined with electron backscatter diffraction (EBSD) analysis system, field-emission transmission electron microscope (FE-TEM), an ohm meter, and a nanoindenter. Additionally, the adhesion of the Cu pillars to an ABF substrate after high-temperature storage was evaluated via a shear test. Finally, a finite element analysis (FEA) method (COMSOL-Multiphysics) was employed to simulate the current density and electrolyte distributions in a via structure upon high-speed Cu electrodeposition to characterize the morphological/crystallographic/mechanical transitions induced by increasing j. This valuable information advances our understanding of electrochemical metal deposition and would be helpful in the development of high-speed Cu electrodeposition technology.