We introduce a novel approach to the synthesis of high-quality and highly uniform few-layer graphene on silicon wafers, based on solid source growth from epitaxial 3C-SiC films. Using a Ni/Cu catalytic alloy, we obtain a transfer-free bilayer graphene directly on Si(100) wafers, at temperatures potentially compatible with conventional semiconductor processing. The graphene covers uniformly a 2″ silicon wafer, with a Raman I D/I G band ratio as low as 0.5, indicative of a low defectivity material. The sheet resistance of the graphene is as low as 25 Ω/square, and its adhesion energy to the underlying substrate is substantially higher than transferred graphene. This work opens the avenue for the true wafer-level fabrication of microdevices comprising graphene functional layers. Specifically, we suggest that exceptional conduction qualifies this graphene as a metal replacement for MEMS and advanced on-chip interconnects with ultimate scalability.

The finite element method is used to simulate indentation with a 100 nm spherical indenter on Al/Pd multilayer thin films and Al and Pd monolayer thin films. The elastic/plastic properties of bulk Al and Pd and the material formulation are obtained by molecular dynamics simulations of tensile and indentation loadings. Hill's plasticity with isotropic hardening is found to best represent the stress–strain response of both bulk Al and Pd. The Pd monolayers appear the hardest and the Al monolayers the softest. The indentation hardness of both monolayered and multilayered films is found to increase with the indentation depth and appears independent of the layer order and thickness in the multilayer films. The hardness values determined by the finite element method simulations are close to those obtained using the well-known formula of Field and Swain. No hardness enhancement in very thin multilayered films (3–5 nm per layer) is evident, in contrast to experimental reports.

Atomic engineering of complex oxide thin films is now reaching a new paradigm: the possibility to control the cation coordination by oxygen anions. Here, we show two examples of stabilization of novel structural phases by manipulating the oxygen sublattices in complex Cu-based oxide thin films grown on SrTiO3: (i) epitaxial strain stabilization of a near cubic form of CuO and (ii) thickness-dependent structural transformation from bulk planar (polar) to chain-type (nonpolar) in SrCuO2 thin films that relieves the electrostatic instability. Experimental investigation on ultrathin CuO layer identifies the existence of an elongated (c/a ∼ 1.34) rocksalt-type CuO phase, pointing to metastable 6-fold coordinated Cu with the hole occupied in the 3dx2−y2 orbital. For ultrathin SrCuO2 layers, we demonstrate the possibility of moving oxygen ion from CuO2-plane to Sr-plane forming chain-type structure. X-ray absorption spectroscopy reveals preferential hole-occupation at the Cu-3d3z2−r2 orbital for chain-type structure unlike to the planar case. Our findings testify unique stabilization processes through atomic rearrangement and provide new insight into the experimental realization of novel cuprate-hybrids to look for exciting electronic properties.

Irradiation is one of the characteristic conditions that nuclear wasteforms must withstand to assure integrity during their service life. This study investigates gamma irradiation resistance of an early age slag cement-based grout, which is of interest for the nuclear industry as it is internationally used for encapsulation of low and intermediate level radioactive wastes. The slag cement-based grout withstands a gamma irradiation dose of 4.77 MGy over 256 h without reduction in its compressive strength; however, some cracking of irradiated samples was identified. The high strength retention is associated with the fact that the main hydration product forming in this binder, a calcium aluminum silicate hydrate (C–A–S–H) type gel, remains unmodified upon irradiation. Comparison with a heat-treated sample was carried out to identify potential effects of the temperature rise during irradiation exposure. The results suggested that formation of cracks is a combined effect of radiolysis and heating upon irradiation exposure.

A method based on the electroforming technique has been proposed for the fabrication of nanoparticle-reinforced copper-matrix composites using an electrolyte of copper sulfate–sulfuric acid solution containing 1 cm3/L of the nanoparticles without surfactants. Of the tested nanoparticles such as Al2O3, SiO2, TiO2, ZrO2, and CeO2, whose sizes ranged from 10 to 30 nm, only TiO2 nanoparticles were successfully embedded in the copper matrix during electroforming, owing to their positive charge in the electrolyte solution. It should be noted that there was very little contamination in the copper matrix, because surfactants were absent during electroforming. Therefore, the electrical conductivity of the specimen that was electroformed in the electrolytes with TiO2 nanoparticles was not significantly different from that of pure copper. Nevertheless, the hardness, yield, and ultimate tensile strength were significantly improved by a small amount (0.3 mass%) of TiO2 nanoparticles primarily because of strengthening by Orowan mechanics. The electroforming process is thus a promising means to prepare copper-matrix composites with an excellent balance of electrical conductivity and mechanical strengths.

Efficient, reproducible, and precise methodologies for fabricating tissue engineering (TE) scaffolds using three-dimensional (3D) printing techniques are evaluated. Fusion deposition modeling, laser sintering, and photo printing each have limitations, including the materials that can be used with each printing system. However, new and promising resorbable materials are surfacing as alternatives to previously studied resorbable TE materials for 3D printing. One such resorbable polymer is poly(propylene fumarate) (PPF), which can be printed using photocross-linking 3D printing. The ability to print new materials opens up TE to a wide range of possibilities not previously available. The ability to control precise geometries, porosity, degradation, and functionalities present on 3D printable polymers such as PPF shows a new layer of complexity available for the design and fabrication of TE scaffolds.

Organ shortage is a severe challenge worldwide. Three-dimensional (3D) printing, a rapidly developing engineering and materials science tool, holds considerable promise in generating implantable organ scaffolds that may reduce or eliminate organ shortage. However, translation of 3D printing into clinical therapies has been astonishingly slow and certainly has not matched the pace of technology development. This review outlines challenges and opportunities for the application of 3D printing in tissue and organ regeneration, with emphasis on in vivo applications of 3D-printed scaffolds. Three-dimensional-printed scaffolds for the regeneration of complex tissues and organs, including bone, cartilage, tooth, and skin, serve as prototypes for 3D printing of other tissues and organs such as the liver, kidney, or heart. The aspiration to reduce or eliminate organ shortage appears to hinge on the translation of 3D bioprinting technologies into preclinical studies and clinical trials. The remaining challenges of cell survival, directed differentiation, angiogenesis, and metabolic exchange are far from trial and need to be addressed. Three-dimensional-printed materials will remain a biomaterials and engineering showcase unless applications in preclinical and clinical models are realized. In balance, 3D printing holds considerable promise in regenerative medicine as a unique approach to address organ shortage.

The long-term success of an orthopedic implant largely depends on the extent of its osseointegration in the surrounding bone. During recent decades, there have been several attempts to develop porous structures and coatings in order to maximize the bone ingrowth on prosthesis surfaces. Innovative additive manufacturing technologies, such as electron beam melting (EBM), which are based upon building components by adding layers of material rather than by removing material from a raw shape, can provide a breakthrough solution, both to overcome the major limitations of the actual technologies and to significantly enhance the performance of porous scaffolds. This article reviews the latest developments in EBM technology applied to the preparation of highly biocompatible porous materials such as Trabecular Titanium and the production of orthopedic prostheses with enhanced characteristics.

Three-dimensional (3D) printing represents the direct fabrication of parts layer-by-layer, guided by digital information from a computer-aided design file without any part-specific tooling. Over the past three decades, a variety of 3D printing technologies have evolved that have transformed the idea of direct printing of parts for numerous applications. Three-dimensional printing technology offers significant advantages for biomedical devices and tissue engineering due to its ability to manufacture low-volume or one-of-a-kind parts on-demand based on patient-specific needs, at no additional cost for different designs that can vary from patient to patient, while also offering flexibility in the starting materials. However, many concerns remain for widespread applications of 3D-printed biomaterials, including regulatory issues, a sterile environment for part fabrication, and the achievement of target material properties with the desired architecture. This article offers a broad overview of the field of 3D-printed biomaterials along with a few specific applications to assist the reader in obtaining an understanding of the current state of the art and to encourage future scientific and technical contributions toward expanding the frontiers of 3D-printed biomaterials.