The aging behavior of precipitation hardenable 17-4 PH stainless steel is studied by analyzing the changes in microstrain, crystallite size, and dislocation density derived from the modified Williamson–Hall (mWH) method and the Fourier analysis of XRD profiles. Aging treatment of this steel at 380, 430, and 480 °C for 0.5, 1, and 3 h durations leads to changes in the microstrain due to precipitation and substructural changes caused by dislocation annihilation. The microstrain estimated from the mWH method is dominated by the precipitate-induced effects. The influence of precipitates and dislocations on the mean squared strain 〈ε2(L)〉 are separated by fitting the variation of 〈ε2(L)〉 with an expression P 0 + P 1/L + P 2/L 2, where the parameter (P 0)0.5 and P 1 are shown to be related to the precipitate-induced and dislocation density-induced microstrain, respectively. The study shows that the XRD profile analysis can be used to separate the combined effects of precipitation and dislocation annihilation.

Methylammonium-tin-iodide (MASnx I3, 0.9 ≤ x ≤ 1.4) systems were prepared by self assembly process in aqueous solutions. The “as-prepared” MASnx I3 systems exhibit a crystalline tetragonal structure (space group I4cm) with polyhedral-shaped crystallites. The as-prepared samples were annealed at T = 150 °C, t = 8 h under nitrogen and synthetic air. Under nitrogen, the CH3NH3Snx I3 systems adopted a cubic crystalline structure (space group P4mm) with crystallites of 2–4 μm length, whereas under air, the formation of noncrystalline phases was observed. The optical absorption spectra displayed absorption edges at 1107.0 nm (x = 0.9), 1098.6 nm (x = 1.0), and 1073.2 nm (x = 1.1), respectively, whereas at higher Sn-content (x ≥ 1.2), a broad tail of the absorbance profile was observed. The photoluminescence (PL) emission spectra (RT, λexc = 500 nm) showed major PL-events over 1 µm range and the appearance of additional bands at increasing the Sn-content. The fabrication of layers with a semiconducting behavior was demonstrated.

Nickel thin films were prepared by electroless plating in a foam of electrolyte that was generated by bubbling nitrogen gas into a hypophosphite-based electroless plating solution to which was added a surfactant of sulfuric acid monododecyl ester sodium salt. Although the film growth rate in the foam was considerably lower than that in the conventional liquid, film growth was enhanced by inducing a flow in the foam. Compared with films deposited in liquid, the films deposited in foam had a smaller number of pinholes, smaller crystallite size, and superior corrosion resistance. The ferroxyl indicator test showed that the area of corrosion can be reduced to less than 1/20 by depositing the film in foam instead of liquid.

The successful applications of graphene nanomaterials in nanobiotechnology and medicine as well as their effective translation into real clinical utility hinge significantly on a thorough understanding of their nanotoxicological profile. Of all aspects of biocompatibility, the hemocompatibility of graphene nanomaterials with different blood constituents in the circulatory system is one of the most important elements that needs to be well elucidated. Once administered into biological systems, graphene nanomaterials may inevitably come into contact with the surrounding plasma proteins and blood cells. Crucially, the interactions between these hematological entities and graphene nanomaterials will influence the overall efficacy of their biomedical applications. As such, a comprehensive understanding of the hemotoxicity of graphene nanomaterials is critically important. This review presents an up-to-date elucidation of the hemotoxicity of graphene nanomaterials through their interactions with blood proteins and cells, as well as offers some perspectives on the current challenges, opportunities, and future development of this important field.

Bistable Auxetic Metamaterials (BAMs) are a class of monolithic perforated periodic structures with negative Poisson’s ratio. Under tension, a BAM can expand and reach a second state of equilibrium through a globally large shape transformation that is ensured by the flexibility of its elastomeric base material. However, if made from a rigid polymer, or metal, BAM ceases to function due to the inevitable rupture of its ligaments. The goal of this work is to extend the unique functionality of the original kirigami architecture of BAM to a rigid solid base material. We use experiments and numerical simulations to assess performance, bistability, and durability of rigid BAMs at 10,000 cycles. Geometric maps are presented to elucidate the role of the main descriptors of the BAM architecture. The proposed design enables the realization of BAM from a large palette of materials, including elastic-perfectly plastic materials and potentially brittle materials.

Harnessing the properties of imidazolium species, antimicrobial activity against Gram-negative and Gram-positive bacteria was attained by binary-grafting 2-hydroxyethyl methacrylate (HEMA) or N-isopropylacrylamide, followed by N-vinylimidazole onto polypropylene (PP) monofilaments (sutures) using 60Co γ-rays. Ulterior functionalization with methyl iodide was carried out to endow brushes with antimicrobial activity on the PP surface. The PP-grafted sutures were characterized by means of Fourier-transform infrared spectroscopy attenuated total reflection, scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis, and regarding the mechanical properties and the responsiveness to pH and temperature. Tests were performed on Escherichia coli and Staphylococcus aureus achieving large inhibition zones.

Because of its unique properties and promising applications, graphene has attracted great interest from both academia and industry in the last decade. For studies on graphene as well as for applications, it is essential to develop techniques to prepare graphene in a controllable way. Graphene can be produced in the form of nano-/microflakes using a top-down method by the exfoliation of graphite or the reduction of graphene oxide, or in the form of a film or foam in a bottom-up method, predominantly by chemical vapor deposition of carbon precursors on catalytic substrates. This article focuses on the catalytic substrates, especially metals, used for graphene growth. We also discuss graphene growth mechanisms and kinetics, control of the number of graphene layers and their stacking order, engineering of large-area graphene single crystals, as well as low-temperature growth.

Nanocarbons, such as carbon nanotubes and graphene, have had a remarkable history and impact on current applications. We briefly review the genesis and development of nanocarbons over the last 50 years, referencing key articles, including the role of catalysts in their formation. This issue focuses on the formation mechanisms and controlled growth of carbon nanotubes and graphene on substrates through catalytic processes. The five contributions in this issue review the mechanisms and theory of catalytic growth of nanocarbons (carbon nanotube forests, superaligned arrays, single-wall carbon nanotubes), the growth of large-quantity, high-quality graphene on metal substrates, and the unique and excellent properties for current and potential commercial applications.

When the size and spacing of catalyst nanoparticles are well controlled on a substrate, carbon nanotubes (CNTs) can grow and assemble into a unique, vertically aligned structure frequently called a “forest.” Long, aligned, and pure CNTs can easily be synthesized in simple or highly complex configurations. First reported in 1996, CNT forests have been shown to be unique and useful forms of CNTs, as they have spurred the development of novel processes and applications and in addition, served as test beds for investigations into CNT growth mechanisms. This article provides an overview of two decades of research in this area.