This work aims at providing guidance through systematic experimental characterization for the design of 3D-printed scaffolds for potential orthopedic applications, focusing on fused deposition modeling with a composite of clinically available polycaprolactone (PCL) and β-tricalcium phosphate (β-TCP). First, we studied the effect of the chemical composition (0–60% β-TCP/PCL) on the scaffold’s properties. We showed that surface roughness and contact angle were, respectively, proportional and inversely proportional to the amount of β-TCP and that degradation rate increased with the amount of ceramic. Biologically, the addition of β-TCP enhanced proliferation and osteogenic differentiation of C3H10. Second, we systematically investigated the effect of the composition and the porosity on the 3D-printed scaffold mechanical properties. Both an increasing amount of β-TCP and a decreasing porosity augmented the apparent Young’s modulus of the 3D-printed scaffolds. Third, as a proof of concept, a novel multimaterial biomimetic implant was designed and fabricated for potential disc replacement.

An efficient representative volume element generation strategy is developed in modeling nanoporous materials. It uses periodic 3D beam finite element (FE) models derived from skeletonization of spinodal-like stochastic microstructures produced by a leveled random field. To mimic stiffening with agglomeration of the mass at junctions, an increased Young’s modulus is assigned to the elements within the junction zone. The effective Young’s modulus, Poisson’s ratio, and universal anisotropy index are computed. A good agreement of the Young’s modulus predictions with those obtained from experimental results for phase volume fractions $0.20 \lt {\phi _{\cal B}} \lt 0.50$ is observed. Moreover, the elastic anisotropy index of the generated beam networks shows sufficient proximity to isotropy. Finally, it is demonstrated that, as compared to the simulation statistics of voxel-FE models, for the beam-FE models over 500-fold computational acceleration with 250-fold less memory requirement is provided.

Flexibility is a key parameter of device mechanical robustness. The most profound challenge for the realization of flexible electronics is associated with the relatively low flexibility of power sources. In this article, two kinds of energy applications, which have gained increasing attention in the field of flexibility in recent years, are introduced: the lithium-ion batteries and the supercapacitors. We overview the latest progresses in flexible materials and manufacturing technology. The performances of the energy devices based on flexible materials are introduced. The advantages and disadvantages of different manufacturing processes are discussed systematically. We then focus on current technical difficulties and future prospects of research in flexibility.

Nanoindentation experiments performed in 5 and 18 μm thick vapor deposited polycrystalline lithium films at 31 °C reveal the mean pressure lithium can support is strongly dependent on length scale and strain rate. At the smallest length scales (indentation depths of 40 nm), the mean pressure lithium can support increases from ∼23 to 175 MPa as the indentation strain rate increases from 0.195 to 1.364 s−1. Furthermore, these pressures are ∼46–350 times higher than the nominal yield strength of bulk polycrystalline lithium. The length scale and strain rate dependent hardness is rationalized using slightly modified forms of the Nabarro–Herring and Harper–Dorn creep mechanisms. Load–displacement curves suggest a stress and length-scale dependent transition from diffusion to dislocation-mediated flow. Collectively, these experimental observations shed significant new light on the mechanical behavior of lithium at the length scale of defects existing at the lithium/solid electrolyte interface.

Special needs patients often require specific dental treatments and modified restorative materials that reduce clinical discomfort. Starting from glass ionomer cements (GICs), some different fillers were added to improve their mechanical and clinical performances. The effect of nanohydroxyapatite, antibiotic, and mucosal defensive agent on the mechanical and thermal properties of GICs was investigated. Compressive tests, calorimetric analysis, and morphological investigation were conducted. The middle percentages of fillers increased the elastic modulus while the highest decreases are recorded for highest percentages. Filler and environment also influence the compressive strengths and toughness. The introduction of fillers led to a reduction of the enthalpy with a maximum decrease with the middle percentage. The morphological characterization showed a good dispersion of the fillers. The filler percentages should be selected with a compromise between the elastic modulus, the compressive strength, and the curing time. Obtaining new materials with good clinical and mechanical properties can represent an innovative aspect of this work with positive implication in clinical practice, mainly in uncollaborative patients in which the use of traditional protocols is problematic.

To obtain a fine-grained Mg matrix, the (submicron + micron) bimodal size SiC particle reinforced AZ91 (SiCp/AZ91) composite was subjected to forging followed by the extrusion process first. Then, the fine-grained bimodal size SiCp/AZ91 composite was compressed at 270–370 °C with 0.1–0.001 s−1. The result indicated that the refinement of the Mg matrix contributed to its deteriorated strength at high temperature. However, the grain size is not the only factor influencing flow stress but the SiCp also plays an important role. The effect of SiCp on the fine grained Mg matrix depends on grain size and dislocation density, both of which strongly depend on temperature and strain rate. As compared with the fine grained Mg matrix reinforced by single size SiCp, the one with bimodal size SiCp unusually exhibit lower flow stress during hot compression. The calculated activation energy of the bimodal size SiCp/AZ91 composite is higher than the micron SiCp/AZ91 composite; however, nearly the same as the submicron SiCp/AZ91 composite, and the deformation of which was thought to be controlled by ∼1 vol% submicron SiCp.

Organic gels obtained by sol–gel polycondensation reaction followed by subcritical drying in ambient conditions are termed as xerogels which are pyrolyzed to yield carbon xerogels. Resorcinol formaldehyde (RF) derived carbon xerogels have received considerable attention due to their higher carbon yield and ease of tuning their microstructure and therefore physiochemical properties. Recent advances in the synthesis of carbon xerogels have allowed porous as well as non-porous but large external surface area morphologies. Further efforts have been made about increasing the surface area by activation or changing the microstructure by doping with foreign elements. These advances in the area of carbon xerogels synthesis led to their use as high performance anode materials for Li ion batteries recently. This review summarizes these recent studies on electrochemical performance of carbon xerogels to clearly demonstrate their potential as high capacity anode material for Li ion batteries. Notably, given the potential not only for Li ion batteries but also for latest sodium-ion batteries and super-capacitors, this review provides a much needed attention of scientific community to so far unnoticed carbon xerogel materials.

Activation of persulfate (PS) by ultraviolet light or transition metal catalysts has been extensively studied. However, little is known about the activation of PS by iron oxychloride (FeOCl) in the presence of visible light irradiation. Herein, the catalytic activity of FeOCl was developed for oxidative degradation of rhodamine B (RhB) with the FeOCl/PS/Vis process. The characterization of FeOCl for reaction kinetics, degradation mechanism, and catalyst stability was investigated. It is found that the redox cycle of iron species and photoinduced electrons formed on the FeOCl catalyst surface can effectively activate PS, to generate radicals. Based on quenching experiments and electron paramagnetic resonance, the photogenerated holes (h+) and sulfate radicals (SO4−•) are the predominant reactive oxidants for RhB decolorization, while superoxide radicals (•O2−) and hydroxyl radicals (•OH) are also involved. Moreover, FeOCl shows good catalytic performance in a wide range of pH values (pH = 3–10) and excellent reusability and stability, as well.

We developed a facile hydrothermal method to synthesize gold nanoplates with the assistance of surfactant cetyltrimethylammonium chloride (CTAC). Gold nanostructure shapes from triangular, truncated triangular to hexagonal morphology with different sizes can be obtained by accommodating the molar ratios of the surfactant to the gold precursor ([CTAC]/[HAuCl4]). The edge width of gold nanoplates could also be adjusted from tens to hundreds of nanometers, and even several microns. The growth mechanism analysis reveals that the surfactant CTAC directs and promotes the growth of the tabular {111} facets to form nanoplate structures with the size and shape variations. The structure-dependent localized surface plasmon resonance of different gold nanoplates was theoretically and experimentally explained by finite element method simulation and surface-enhanced Raman scattering (SERS) enhancement, respectively. Based on the Raman spectrum analysis of the marker molecule 4-mercaptobenzoic acid (4-MBA) labeled with different gold nanoplates, it demonstrates that the enhanced SERS performance relies on the different plasmonic properties of the gold nanoplates. Therefore, the gold nanoplates may have potential applications in SERS-based sensing and imaging field.

Intercalated and unmodified TiS2 nanomaterials were synthesized and characterized by UV-Visible-NIR spectroscopy, Powder X-Ray Diffraction, and X-Ray Photoelectron and Ultraviolet Photoelectron Spectroscopy. Photoelectron spectroscopy measurements indicated that CoS and Cu2S appeared to be intercalated between sheets of partially or fully oxidized TiS2, which could be solution processed on conductive oxide substrates. The materials were then applied toward water oxidation and evaluated by cyclic voltammetry, chronoamperometry, and impedance measurements. While unmodified TiS2 was not observed to perform well as an electrocatalyst with overpotentials >3 V in 1 M NaOH electrolyte, CoS intercalation was found to lower the overpotential by ∼1.8–1.44 V at 10 mA/cm2. Conversely, Cu2S intercalation resulted in only a modest increase in performance (>2.3 V overpotential). Impedance measurements indicated that intercalation increased the series resistance in the as-prepared samples but decreased the series resistance in oxidized samples.

High-index ferroelectric thin films show excellent dielectricity, piezoelectricity and switching behaviors. Understanding the misfit strain relaxation behavior may prove beneficial to gaining insights into the high-quality growth of high-index ferroelectric films. In this study, ferroelectric PbTiO3 thin films were deposited on the (101)-oriented (La, Sr)(Al, Ta)O3 substrate by pulsed laser deposition and were investigated using (scanning) transmission electron microscopy. Two types of misfit dislocations with line directions of 〈111〉 and [010] were found at the interface. The 〈111〉 dislocation exhibited Burgers vectors of a[011] or $a\left[ {0\bar{1}1} \right]$, while the [010] dislocation featured Burgers vectors of $a\left[ {\bar{1}01} \right]$. The former might be generated by gliding, and the latter by climbing. We propose that the misfit strain relaxation in this film system basically results from the formation of dislocations and the residual misfit strain is relaxed via the formation of 90° ac domains.

Recent discoveries of multicomponent concentrated solid-solution alloys hold promise for enhanced properties—such as enhanced mechanical properties, radiation tolerance, high temperature strength, corrosion resistance and some novel functional properties, provide a new strategy for alloy design using extreme disorder. Yet, deep understanding of these intriguing properties is complicated by the very effects of disorder that make them interesting. All the desirable properties of these alloys ultimately originate from the disorder-induced properties of underlying electronic structure, lattice dynamics, and thermodynamics. Therefore, understanding the disorder-induced fundamental physical properties is prerequisite for the science-based design of this class of alloys for practical applications. Here, we elucidate the role of extreme (maximal) substitutional disorder plays in the fundamental physics of disordered alloys and review the recently developed theoretical methodologies in modeling the basic physical properties, particularly electronic structure, magnetism, electrical transport, and lattice vibrations in multicomponent concentrated solid-solution alloys.

Boron nitride nanotubes (BNNTs) have been utilized to strengthen various engineering materials especially metal matrix composites thanks to their extraordinary high tensile strength, elastic modulus, and failure strain. In this paper, single- and multi-walled BNNTs were therefore used to combine with aluminum (Al) metal matrix. Mechanical characteristics and deformation mechanism of nanocomposites reinforced with long (continuous) and short (discontinuous) BNNTs were then investigated for different loadings including uniaxial tension and compression and different boundary conditions based on molecular dynamics simulations. It was found that long BNNTs remarkably improved tensile mechanical properties of the matrix and effectively enhanced elastic modulus and strength of the nanocomposites by 82% and 79.4%, respectively. They could provide effective barriers to propagation path of dislocations formed inside the matrix. Diameter and wall number of the reinforcement did not leave considerable impacts on the nanocomposite behavior while its atomic fraction remarkably influenced the material response.

Metal–resin interpenetrating phase composites (IPCs) have been produced by spontaneously infiltrating unsaturated polyester resin into porous stainless steel fibrous preforms under vacuum conditions. The compressive behaviors of the IPCs were investigated and the fractures were examined. The compressive strength and elastic modulus increase with increasing fiber fraction. The structures, compressive behaviors, and energy absorption capacities of the IPCs exhibit anisotropy. A higher compressive strength, lower elastic modulus, and lower energy absorption efficiency are observed in the through-thickness direction. The energy absorption efficiency slightly decreases with increasing fiber fraction in a certain range rather than monotonically increasing or decreasing. The energy absorption efficiency in the in-plane direction is superior to that in the through-thickness direction. Finer fibers improve the strength and elastic modulus but have little influence on the energy absorption efficiency. Resin collapse, fiber necking, and debonding are the main failure types observed in the composites.

Wollastonite (CaSiO3)–diopside (CaMgSi2O6) glass-ceramic scaffolds have been successfully fabricated using two different additive manufacturing techniques: powder-based 3D printing (3DP) and digital light processing (DLP), coupled with the sinter-crystallization of glass powders with two different compositions. The adopted manufacturing process depended on the balance between viscous flow sintering and crystallization of the glass particles, in turn influenced by the powder size and the sensitivity of CaO–MgO–SiO2 glasses to surface nucleation. 3DP used coarser glass powders and was more appropriate for low temperature firing (800–900 °C), leading to samples with limited crystallization. On the contrary, DLP used finer glass powders, leading to highly crystallized glass-ceramic samples. Despite the differences in manufacturing technology and crystallization, all samples featured very good strength-to-density ratios, which benefit their use for bone tissue engineering applications. The bioactivity of 3D-printed glass-ceramics after immersion in simulated body fluid and the similarities, in terms of ionic releases and hydroxyapatite formation with already validated bioactive glass-ceramics, were preliminarily assessed.

High-entropy and multiprincipal element alloys present exciting opportunities and challenges for computational modeling of their structure and phase stability. Recent interest has catalyzed rapid development of techniques and equally rapid growth of new results. This review surveys the essential concepts of thermodynamics and total energy calculation, and the bridge between them provided by statistical mechanics. Specifically, we review the electronic density functional theory of alloy total energy as applied to supercells and special quasirandom structures. We contrast these with the coherent potential approximation and semi-empirical approximations. Statistical mechanical approaches include cluster expansions, hybrid Monte Carlo/molecular dynamics simulations, and extraction of entropy from correlation functions. We also compare first-principles approaches with Calculation of Phase Diagrams (CALPHAD) and highlight the need to augment experimental databases with first-principles derived data. Numerous example applications are given highlighting recent progress utilizing the concepts and methods that are introduced.

Molecular dynamics (MD) is one of the most widely used techniques in computational materials science. By providing fully resolved trajectories, it allows for a natural description of static, thermodynamic, and kinetic properties. A major hurdle that has hampered the use of MD is the fact that the timescales that can be directly simulated are very limited, even when using massively parallel computers. In this study, we compare two time-parallelization approaches, parallel replica dynamics (ParRep) and parallel trajectory splicing (ParSplice), that were specifically designed to address this issue for rare event systems by leveraging parallel computing resources. Using simulations of the relaxation of small disordered platinum nanoparticles, a comparative performance analysis of the two methods is presented. The results show that ParSplice can significantly outperform ParRep in the common case where the trajectory remains trapped for a long time within a region of configuration space but makes rapid structural transitions within this region.

Graphitic carbon nitride (g-C3N4) microspheres (CNMS) were fabricated via a solvothermal method by using dicyandiamide and cyanuric chloride as precursors. The morphology, band structure, and defects can be simultaneously regulated by merely adjusting the concentration of precursors. Structural characterization results indicate that all the prepared samples possess spherical morphology, while the band gap decreased as the precursor concentration increased from 8 mmol (CNMS-1) to 24 mmol (CNMS-3). Besides, ultraviolet photoelectron spectroscopy results suggested that the valence band of CNMS-2 (16 mmol) was much higher than that of CNMS-1 and CNMS-3. Additionally, organic elemental analysis, X-ray photoelectron spectroscopy, and electron paramagnetic resonance results unveil the formation of nitrogen defects on the surface of prepared samples. Besides, CNMS-2 exhibits an enhanced apparent reaction rate constant of RhB degradation than that of CNMS-1 and CNMS-3. The improved apparent reaction rate constant may be due to the lowered valence band as well as the formation of nitrogen defects. This work might guide the regulation of the morphology and band structure of g-C3N4-based materials prepared via the one-pot hydrothermal method.

Replacing precious and nondurable platinum-based catalysts by economical and commercially available materials is a key issue addressed in contemporary fuel cell technology. Carbon-based nanomaterials display great potential to improve fuel tolerance and reduce the cost and stress on metal scalability. However, their relatively low catalytic activity limits the development and application of these catalysts. In this study, we have synthesized a nitrogen-doped carbon electrocatalyst from metal–organic frameworks and carbon nanotube composites, taking advantage of the existing N in the organic linker in the MOFs with more N added through ammonia treatment. The morphology and composition of synthesized catalysts were characterized by SEM, TEM, XPS, and Raman. The derived catalyst exhibited superior catalytic activity than that of commercial Pt-based catalysts. The N enriched carbon catalyst with high surface area, a graphitic carbon skeleton, and a hierarchical porous structure facilitated the mass and charge transfer during electrolysis.

The microstructure evolution of the directionally solidified NiAl–Cr(Mo) planar eutectic lamellar structure was studied at 1150 °C and times of up to 400 h. The planar eutectic lamellar structure is obtained at the withdrawal rate range of 2.5–7.5 μm/s. The interlamellar spacing decreases gradually with increasing the withdrawal rate. The lamellar termination (like angular or smooth) commonly exists in the as-DS alloy. After high temperature treatment, the lamellar structure at 2.5 μm/s (interlamellar spacing, 3.7 μm) is almost stable, only a little migration of termination occurs at 400 h. When the withdrawal rate increases to 4.5 μm/s, the coarsening and migration of termination occur at 200 h. The adjacently coarsened terminations assemble when the coarsening processes to a certain degree, thus resulting in the formation of the blocky Cr(Mo) phase. Similarly, the above instable phenomenon occurs at 7.5 μm/s. The relevant instability mechanisms are discussed.