In this study, the effects of 3D-printed SiO2 and ZnO-doped tricalcium phosphate (TCP) scaffolds with interconnected pores were evaluated on the in vivo bone formation and healing properties of a rabbit tibial defect model. Pure and doped TCP scaffolds were fabricated by a ceramic powder-based 3D printing technique and implanted into critical sized rabbit tibial defects for up to 4 months. In vivo bone regeneration was evaluated using chronological radiological examination, histological evaluations, SEM micrographs, and fluorochrome labeling studies. Radiograph results showed that Si/Zn-doped samples had slower degradation kinetics than the pure TCP samples. 3D printing of TCP scaffolds improved bone formation. The addition of dopants in the TCP scaffolds improved osteogenic capabilities when compared to the pure scaffolds. In summary, our findings indicate that the addition of dopants to the TCP scaffolds enhanced bone formation and in turn leading to accelerated healing.

Efficient applications of magnetic cores in sensing and power electronics require low-loss and versatile soft magnetic materials, with excellent response on a wide range of frequencies. This objective is traditionally pursued with ferrite and Permalloy tape cores, available under a variety of properties. Comparable and even superior soft magnetic behavior can, however, be obtained with amorphous and nanocrystalline alloys, with the latter, in particular, combining flexible response to thermal treatments with high magnetic saturation. Broadband precise magnetic characterization of these materials, crucial to their use as inductive cores, is fully appreciated when associated with assessment by physical modeling. Comprehensive measuring approach and significant results obtained in sintered soft ferrites and nanocrystalline ribbons up to 1 GHz are highlighted in this paper. We show how broadband loss and permeability behaviors can be quantitatively interpreted in the framework of the loss separation concept, applied to eddy current and spin damping dissipation mechanisms.

Nanoporous metallic foams with high surface area and novel functional behavior are positioned to stimulate new multifunctional and metamaterial applications. However, there are fundamental challenges in achieving uniform nanopores and tailorable morphology. Emerging templating methods offer a wide range of applicable metallic species while enhancing control of pore morphology, uniformity, and interconnectivity. Here, a critical review of nanoporous metal fabrication is presented, with focus on templating methods utilizing nanoporous polymeric templates. Metals are introduced into percolative nanochannels of sacrificial templates by deposition, and subsequent removal of templates yields ordered nanoporous metals. We introduce approaches for preparing nanoporous templates, including utilizing block copolymer self-assembly that yields periodic gyroid networks. While metallization of templates by electrodeposition has been demonstrated, electroless deposition permits uniform deposition by many metallic species and infiltration of narrow pores. Examples of nanoporous metals with uniform pore sizes below 50 nm fabricated by templating methods are examined.

A systematic investigation of influence of the laser hatch style on densification behavior, microstructure, and tribological performance of aluminum parts’ preparation by selective laser melting (SLM) was implemented in this study. The scans with checker board (CB) style left better processing quality of surface morphology and few metallurgical defects to SLM parts in comparison with single fill and cross fill styles, hence leading to a relatively high densification level (99.42%). The CB style of shorter scan length left higher undercooling degree in small checker areas compared with other longer scan lengths, leading to finer equiaxed grains to the solidification microstructure. Accordingly, an enhanced mean microhardness of 129.7 HV0.1 was obtained in this hatch style, due to the grain refinement strengthening effect. The lowest coefficient of friction of 0.49 and wear rate of 2.43 × 10−4 mm3/(N m) were obtained. The improved densification level and formation of refined equiaxed grain and evenly distributed ring-shaped Si particles formed in CB parts changed the mechanism of material removal during sliding from the abrasion to adhesion of the tribolayer, significantly improving the wear resistance of SLM aluminum parts.

Structural hierarchy is ubiquitous in nature and quite important for optimizing the properties of functional materials. Carbon nanomaterials, owing to their unique and tunable physical and chemical properties, have been regarded as promising candidates for various energy storage systems. Constructing hierarchically structured carbon nanomaterials (HSCNs) can boost electrochemical performance of nanocarbons. Therefore, HSCNs have attracted tremendous research attentions in recent years. In this review, we summarized the recent progress in hierarchical structure design of carbon nanomaterials and their potential applications in different energy storage technologies. First we give a brief introduction about carbon nanomaterials and the hierarchical structure merits. Subsequently, recent research works on hierarchical structure design of carbon nanomaterials was summarized and classified according to applications in lithium-ion batteries, sodium-ion batteries, supercapacitors and lithium–sulfur batteries, respectively. In addition, the challenges of HSCNs in different applications were also concluded and reviewed. At last, design principles of HSCNs were summarized and future development trends were prospected.

Three-dimensional Ni3S2-reduced graphene oxide (rGO) nanosheets composite is directly grown on nickel foam (Ni3S2-rGO@NF) by a one-step hydrothermal process involving in situ sulfurization of NF and reduction of GO. The introduction of GO is found not only to control the aggregation and the growth of Ni3S2 nanosheets, but also to increase the number of active sites and improve conductivity of composite. The heterogeneous Ni3S2-rGO@NF electrode as electrocatalysts for hydrogen evolution reaction (HER) exhibits significantly enhanced catalytic activity in alkaline media. The onset potential of Ni3S2-rGO@NF can be as low as ∼0 mV, which is comparable to platinum, and only a small overpotential of ∼44 mV is needed to reach a benchmark current density of 10 mA/cm2. Moreover, it demonstrates a good stability. All evidences suggest that the in situ surfurization can be considered as an effective way to prepare metal sulfides as electrocatalysts for hydrogen generation.

TiO2 nanomaterials with platelet or nanosheet morphologies can offer improved properties for photocatalytic applications, but established methods to produce them typically require structure-directing agents since anatase-phase TiO2 does not have a layered structure. In the present work, the preparation of TiO2 nanosheets by the chemical oxidation of TiS2 nanosheets is demonstrated. Electrochemical exfoliation of bulk TiS2 into TiS2 nanosheets, followed by the hydrothermal treatment at 180 °C for 14 h is performed. The results show that polycrystalline TiO2 nanosheets with the anatase structure are formed, and that the nanosheet morphology can still be maintained after the hydrothermal treatment. The TiO2 nanosheets show good photocatalytic activity for the degradation of methylene blue, but the performance is negatively affected by the residual carbon black that was needed in the TiS2 electrode to enable electrochemical exfoliation. These results show that conversion of TiS2 nanosheets to TiO2 nanosheets is a promising synthetic strategy but highlights how the interfacial properties of the obtained materials could be affected by ancillary components in the preparation method.

Pure and magnesium-doped TiO2 nanoparticles (NPs) of three different concentrations (3, 6, and 9 mol%) were synthesized by a simple, cost effective solvothermal microwave irradiation method and characterized by XRD, EDAX, transmission electron microscopy (TEM), and UV-Vis diffuse reflection spectroscopy. X-ray diffraction studies performed on synthesized NPs have shown that the anatase phase is preserved after doping and the dopant does not change the crystalline phase (anatase) of the parent material (TiO2). TEM results revealed that the particle size was significantly reduced with increasing dopant concentration and are spherical in shape. For the J–V measurements, the devices were subjected to the simulated sun light of 100 mW/cm2 irradiation with a working electrode area of 0.25 cm2 (0.5 × 0.5 cm). The results show that the dye-sensitized solar cell based on a 3 mol% Mg-doped TiO2 electrode achieved a photoelectrical conversion efficiency of 7.36% which is perceptibly increased by 17.6% than undoped TiO2 (6.26%).

We review the materials paradigm for metal amorphous nanocomposite (MANC) soft magnetic materials to showcase in solid state transformers (SSTs). We report 2D finite element analysis (FEA) of 3-phase SSTs operating at 50 Hz–10 kHz frequencies. We benchmark materials in designs to control high frequency losses and achieve higher power densities. FEA models are solved in the time domain for line frequencies of 50 Hz–10 kHz and 100 KW output power for the first 4 cycles. Transformer topologies are coupled to a power analysis using a Steinmetz parameterization of magnetic losses capturing induction and field scaling for transformer grade Si steel as compared to Metglas, Ferrite, FINEMET, Co- and FeNi-based MANCs. Recently discovered FeNi-based MANCs allow smaller transformers at equivalent power as compared to Si steel, Metglas, and Co-based MANCs. Fe-rich and non-Co containing MANCs also offer economies based on lower raw materials costs compared with Co-based MANCs.

We review two recent advances in coupled quantum mechanics/molecular mechanics (QM/MM) modeling for metallic materials. The QM/MM methods are formulated based on quantum mechanical charge density embedding. In the first method, QM/MM coupling is accomplished by an embedding potential evaluated via orbital-free density functional theory. The charge density embedding in the second QM/MM method is achieved through constrained density functional theory. The extension of QM/MM coupling to the quasicontinuum method is illustrated, offering a route toward quantum mechanical simulations of materials at micron scales and beyond. The theoretical formulations of the QM/MM methods are discussed in detail. We also provide some examples where the QM/MM methods have been applied to understand fundamental physics in a wide range of material problems, ranging from void formation, pipe diffusion along dislocation core, nanoindentation of thin films, hydrogen-assisted cracking, magnetism-induced plasticity to stress-controlled catalysis in metals. An outlook to future development of QM/MM methods for metals is envisioned.

The wettability of the 304L steel is an important parameter in Liquid Metal Embrittlement studies. Empirically, it is found to be greatly enhanced by pre-exposure to oxygenated liquid sodium. The corrosion interface formed during exposure to sodium has been analyzed at the nanoscale by transmission electron microscopy using the focused ion beam sampling. A thin layer of sodium chromite (NaxCrO2 with x ≤ 1) is detected at the interface validating wetting on an oxide mechanism for the enhanced wetting after pre-exposure. Fracture micromechanisms and the crack path of liquid sodium-embrittled austenitic steel 304L at 573 K have been investigated down to the nanoscale. High-resolution orientation mapping analyses immediately below the fracture surface show that abundant martensitic transformations (γ → α) and twinning occur during deformation of austenite. The preferential crack path is intergranular along the newly formed γ/γ interfaces. It is concluded that these transformations play a major role in the fracture process.

The present article addresses design of stiff, elastically isotropic trusses and their mechanical properties. Isotropic trusses are created by combining two or more elementary cubic trusses in appropriate proportions and with their respective nodes lying on a common space lattice. Two isotropic binary compound trusses and many isotropic ternary trusses are identified, all with Young’s moduli equal to the maximal possible value for isotropic strut-based structures. In finite-sized trusses, strain elevations are obtained in struts near the external free boundaries: a consequence of reduced nodal connectivity and thus reduced constraint on strut deformation and rotation. Although the boundary effects persist over distances of only about two unit cell lengths and have minimal effect on elastic properties, their manifestations in failure are more nuanced, especially when failure occurs by modes other than buckling (yielding or fracture). Exhaustive analyses are performed to glean insights into the mechanics of failure of such trusses.

We investigate the photostability of a set of organic semiconductor blends comprising a conjugated polymer as the donor and a fullerene as the acceptor using electron spin resonance (ESR). In the absence of oxygen, all blends show excellent stability. Even after several hundred hours of exposure to solar or UV radiation, the ESR spectra and the recombination of photoinduced charges recorded at low temperature are found to be unchanged. By contrast, the presence of oxygen leads to a fast light-induced degradation rendering the ability of the donor/acceptor system to form photoinduced charge carriers. Our findings suggest that conjugated polymer–fullerene blends exhibit very good photostability and that oxygen needs to be excluded in optoelectronic applications. Our findings also suggest that at low temperature, a universal recombination process of long-lived photoinduced charges is active, which does not depend on the electronic structure or the morphology of the investigated materials.

We present an ab initio study of dopant–dopant interactions in beryllium-doped InGaAs. We consider defect formation energies of various interstitial and substitutional defects and their combinations. We find that all substitutional–substitutional interactions could be neglected. On the other hand, interactions involving an interstitial defect are significant. Specially, interstitial Be is stabilized by about 0.9/1.0 eV in the presence of one/two BeGa substitutionals. Ga interstitial is also substantially stabilized by Be substitutionals. Two Be interstitials can form a metastable Be–Be–Ga complex with a dissociation energy of 0.26 eV/Be. Therefore, interstitial defects and defect–defect interactions should be considered in accurate models of Be-doped InGaAs. We suggest that In and Ga should be treated as separate atoms and not lumped into a single effective group III element, as has been done before. We identified dopant-centred states which indicate the presence of other charge states at finite temperatures, specifically, the presence of Beint +1 (as opposed to Beint +2 at 0 K).

The effect of Si on Fe-rich intermetallic formation and the mechanical properties of the heat-treated squeeze cast Al–5.0Cu–0.6Mn–0.7Fe alloy was investigated. Our results show that increasing the Si content promotes the formation of Al15(FeMn)3(SiCu)2 (α-Fe) and varies the morphology of T (Al20Cu3Mn2), where the size decreases and the amount increases. The major reason is that Si promotes heterogeneous nucleation of the intermetallics leading to finer precipitates. Si addition significantly enhances the ultimate tensile strength and yield strength of the alloys. The strengthening effect is mainly owing to the dispersoid strengthening by increasing the volume fraction of the T phase and less harmful α-Fe with a compact structure, which makes it more difficult for the cracks to initiate and propagate during tensile test. The squeeze cast Al–5.0Cu–0.6Mn–0.7Fe alloy with 1.1% Si shows significantly improved mechanical properties than the alloy without Si addition, which has a tensile strength of 386 MPa, yield strength of 280 MPa, and elongation of 8.6%.

Lithium–sulphur (Li–S) batteries are one of the most promising candidates for the next generation of energy storage systems to alleviate the energy crisis. However, Li–S batteries’ commercialization faces the challenges of low active materials utilization, poor cycling life, and low energy density. Recently, tremendous progress has been achieved in improving the electrode performances and tap density by using the nanostructured metal compounds in Li–S batteries. In this review, we not only present the latest various nanostructured metal compounds applications in Li–S batteries, including metal oxides, metal sulphides, metal carbides, metal nitrides, and metal organic frameworks, but also we focus on the interaction mechanisms between these polar metal compounds with polysulphides. The issues and bottlenecks of these metal compounds are concluded and the corresponding available solutions to address these issues are proposed. This systematic discussion and proposed strategies can offer avenues to the practical application of Li–S batteries in the near future.

Seeking a latent-crosslinkable, mechanically flexible, fully thermoplastic shape memory polymer, we have developed a simple but effective macromolecular design that includes pendent crosslinking sites via the chain extender of a polyurethane architecture bearing semicrystalline poly(ε-caprolactone) (PCL) soft segments. This new composition was used to prepare fibrous mats by electrospinning and films by solvent casting, each containing thermal initiators for chemical crosslinking. The one-step synthesis strategy proved successful, and the crosslinking sites within PCL segments resulted in two-way (reversible) shape memory: repeatable elongation (cooling) and contraction (heating) under constant tensile stress. Being fully characterized, the crosslinked fiber mats revealed promising one-way and two-way (reversible) shape memory phenomena, with lower storage moduli though, compared to uncrosslinked films. We observed for both fibrous mats and films that increasing the applied tensile stress led to greater crystallization-induced elongation upon cooling as well as smaller strain hysteresis, particularly for covalently crosslinked samples. Relevant to medical applications, the materials were observed to feature unique, two-stage enzymatic degradation that was sensitive to differences in crystallinity and microstructure among samples.

The hot deformation behavior of Ti–6Al–4V alloy with starting fully lamellar microstructure was investigated by conducting isothermal hot compression tests at the temperature of 700–1000 °C and strain rate of 0.001–10 s−1. The deformation activation energy is calculated to be 342 kJ/mol at temperatures from 750 to 850 °C, whereas the higher apparent activation energy of 610 kJ/mol is obtained at a high temperature regime of 900–1000 °C. The relationship between the dynamic softening behavior and deformation parameters was analyzed by power dissipation efficiency η, which shows an increasing trend as the deformation temperature increases and strain rate decreases, respectively. Processing maps were constructed. The instability flow is dominated by the presence of adiabatic shear bands, and the dynamic softening is mainly caused by a combination effect of dynamic recrystallization and dynamic recovery. Moreover, straining is found to have a positive effect on lowering the phase transformation temperature.

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.