A quantum computer will have computational power beyond that of conventional computers, which can be exploited for solving important and complex problems, such as predicting the conformations of large biological molecules. Materials play a major role in this emerging technology, as they can enable sophisticated operations, such as control over single degrees of freedom and their quantum states, as well as preservation and coherent transfer of these states between distant nodes. Here we assess the potential of semiconductor nanowires grown from the bottom-up as a materials platform for a quantum computer. We review recent experiments in which small bandgap nanowires are used to manipulate single spins in quantum dots and experiments on Majorana fermions, which are quasiparticles relevant for topological quantum computing.

Recently, fully reversible dislocation motion was postulated to result in hysteretic nanoindentation load–displacement loops in plastically anisotropic solids. Since microcracking can also result in hysteretic loops, here we define a new parameter, reversible displacement (RD) that can differentiate between the two. For C-plane LiTaO3 surfaces and five other plastically anisotropic solids, the RD values either increase initially or remain constant with cycling. In contradistinction, for glass and A-plane ZnO surfaces, where energy dissipation is presumably due to microcracking or irreversible dislocation pileups, respectively, the RD values decreased continually with cycling.

Potential applications of the molecularly imprinted polymers (MIPs) demand physical configurations in different size ranges. Nowadays, research on MIPs is focused on the development of new or improved morphologies, which involves control and modification of the different parameters during the synthesis. In this study, the effect of different synthesis conditions on the particle size and morphology is investigated. Carbamazepine-imprinted polymers were prepared using precipitation polymerization under various conditions such as: the amounts of cross-linker and functional monomers, initiator, porogen, temperature and time of polymerization. We studied the polymerization conditions to obtain imprinted spherical particles with controllable sizes in the range of 243 nm to 3.4 μm. Scanning electron microscopy and photon correlation spectroscopy were utilized to investigate the morphological characterization. The mole ratio of the functional monomer to the cross-linker was important to obtain smaller uniformly sized particles. In addition, the results showed that the cross-linker in the molecular imprinting synthesis can affect the morphology and composition of the MIPs, which influences the binding affinity.

We report here a successful fabrication of three-dimensional (3D) photoelectrodes fully coated with hydrothermally formed TiO2 nanotubes on multi-layered Ti mesh with significantly increased surface area. A near-vertical array of ~8 nm diameter nanotubes of TiO2 was also produced on the metallic surface of folded Ti mesh electrode. The multi-layered mesh was used as a 3D highly conductive electrode, as this architecture intuitively allows for light passage, reflections, and smooth water flow for possible continuous operation of water splitting reaction. By virtue of substantially increased surface area and more efficient light usage, significantly increased photocurrent densities were obtained.

To improve the electrochemical and kinetic performances of the Mg2Ni-type hydrogen storage alloys, Mg was partially substituted by La, and the rapid solidification technology was used for the preparation of Mg20−xLaxNi10 (x = 0, 2, 4, 6) alloys. The microstructures of the as-cast Mg20−xLaxNi10 (x = 0, 2, 4, 6) and as-spun Mg20−xLaxNi10 (x = 2) alloys were systematically studied through x-ray diffraction and high-resolution transmission electronic microscopy. Electrochemical hydrogen storage properties were measured by the automatic galvanostatic system. Electrochemical impedance spectrum, linear polarization, and step-potential discharge curves were plotted using electrochemical workstation. The results showed that substitution of La for Mg was helpful for forming multiphase structures, increasing the discharge capacity of the as-cast Mg20−xLaxNi10 (x = 0, 2, 4, 6) alloys. The increasing quenching rate facilitated the formation of amorphous and nanocrystalline structures of Mg18La2Ni10 (La2) alloy, effectively improving the electrochemical and kinetic properties of Mg18La2Ni10 (La2) alloys.

The mechanisms involved in the formation of titanium (Ti) nanoclusters produced by sputtering and inert gas condensation were investigated experimentally and numerically. Ti nanoclusters were generated inside an ultrahigh vacuum compatible system under different source parameters, i.e., inert gas flow rate (fAr), length of the aggregation region (L), and sputtering discharge power (P). Nanocluster size and yield were measured using a quadrupole mass filter (QMF). The variation of the above source parameters enabled fine-tuning of the nanocluster size and yield. Herein, Ti nanoclusters were produced within the size range 3.0–10.0 nm. The combination between the nanocluster size and yield as a function of source parameters enabled understanding Ti nanocluster formation mechanisms, i.e., three-body and two-body collisions. The results show that two-body collisions dominate nanocluster production at low fAr while the three-body collisions dominate at high fAr. In addition, nanocluster size increases as L increases due to the increase in nanocluster nucleation and growth times. The maximum nanocluster yield was obtained at fAr that maximize the probability of three-body and two-body collisions. Nanoclusters could be produced within an optimum range of the sputtering discharge power wherein the nanocluster size and yield increase with increasing the discharge power as a result of increasing the amount of sputtered material. The experimental results were compared with a theoretical model of nanocluster formation via three-body collision. Detailed understanding of the evolution of size and yield of Ti (and Ti-oxide) nanoclusters is essential for producing nanoclusters that can be utilized for environmental applications such as conversion of carbon dioxide and water vapor into hydrocarbons.

The Ag@SiO2 core–shell structure nanoparticles prepared by chemical method were dispersed into epoxy matrix. By comparing with the epoxy-based composites filled with the mixed Ag and SiO2 nanoparticles (Ag + SiO2), it is found that the Ag@SiO2 core–shell structure fillers had important effects on the improved dielectric properties of the Ag@SiO2/epoxy composites. The core–shell structure fillers introduce a duplex interfacial polarization and a small number of free charge carriers, which enhance the dielectric permittivity of the composites. At the same time, the insulating SiO2 shell layer changes the interfacial interaction between the Ag filler and the epoxy matrix, not only avoiding Ag particles to connect directly and aggregate together but also providing a rough surface to contact with the epoxy host, which enhances the compatibility between the Ag@SiO2 fillers and the epoxy matrix. As the Ag@SiO2 packing ratio increases, the permittivity of the composites straightly increases and the loss tangent decreases, reaching the maximum and minimum respectively with the filler loading up to 60%.

All-oxide ultraviolet (UV) photosensors based on NiO/ZnO nanowire heterostructure were fabricated on corning glass substrates. The p-type NiO layers were directly deposited on the ZnO nanowire arrays grown on the AZO bottom electrode/glass for the formation of a p–n diode, followed by the growth of the ITO top electrode layer for the electrical interconnection of nanostructures. The fabricated device structure showed a transmittance value of about 60% in the visible region, resulting in semitransparent properties. The current–voltage (I–V) characteristics of the fabricated p–n heterostructure showed a typical rectifying behavior with a current rise at about 4 V and an I(forward)/I(reverse) ratio of about 11.3 at 8 V. In addition, the ITO/p-NiO/n-ZnO/AZO structure responded at a wave-length position of 370 nm in reverse bias, together with weak photoresponse in the visible region. An UV sensor based on the all-oxide ZnO nanowire absorber exhibited improved photoresponse compared to the device based on a ZnO thin film.

Nano- and micron-sized metal particles have important applications in catalysis and in the medical and electronic industries. For applications requiring high conductivity, such as thick film conductive pastes or isotropic conductive adhesives, AgCu particles combine high conductivity with advantages of lower costs. Here, we report the generation of AgCu particles by spray pyrolysis, a process that has the advantages of simple experimental setup, large-scale production ability, and controllable particle size. Solutions of copper nitrate and silver nitrate dissolved in deionized water with either 40 vol% ethanol (ET) or 40 vol% ethylene glycol (EG) were used as the precursor. Phase separation was observed during the generation of AgCu particles, and the particles were mainly Ag-rich and Cu-rich solid solutions. The short reactor residence time experiments indicated that both the cosolvent properties and operating conditions affect the particle formation process and change the structure of particles.

Order and porosity of block copolymer membranes have been controlled by solution thermodynamics, self-assembly, and macrophase separation. We have demonstrated how the film manufacture with long-range order can be up-scaled with the use of conventional membrane production technology.

The indole molecularly imprinted polymer (indole-MIP) was synthesized by atom transfer radical emulsion polymerization (ATREP). The novel adsorbent was used to adsorb indole from fuel oil. The indole-MIP had a high selectivity to indole, and the mass transfer limitations were overcome. The property and morphology of indole-MIP were described by a series of characterization methods. A great specific area and more pores of indole-MIP were shown. The static adsorption experiments display that equilibrium adsorption capacity of indole-MIP was 34.488 mg/g. The adsorption process was spontaneous by thermodynamic analysis, and a dense mass of indole was adsorbed onto indole-MIP at a proper low temperature (298 K). Pseudo-second-order kinetic model was more fitted with experimental data. Both Langmuir and Freundlich isotherm models were obeyed by adsorption isotherm test. The selective and competitive performances of indole-MIP were favorable, and the regeneration capacity was appreciable.

There is compelling evidence for the critical role of twin boundaries (TBs) in imparting the extraordinary combination of strength and ductility to nanotwinned metals. Here, we investigate the thermal fluctuations of TBs in face-centered-cubic metals to elucidate the deformation mechanisms governing their kinetic properties using molecular dynamics simulations. Our results show that the TB motion is strongly coupled to shear deformation up to 0.95 homologous temperature. A rather unexpected observation is that coherent TBs do not exhibit any capillarity-induced fluctuations even at high temperatures, in sharp contrast to other high-angle grain boundaries.

In this study, nanocrystalline ZrN films were successfully deposited onto AZ91 alloy using an ion beam sputtering method at substrate temperatures of 373–673 K. Strain and adhesion were calculated using the classic Williamson–Hall and indentation cracking methods, respectively. Microstructure and crystalline properties were evaluated using scanning electron microscopy and x-ray diffraction. XRD results showed that the crystallographic properties of the films were strongly dependent upon substrate temperature. An increase in temperature increased adhesion of the film to the AZ91 alloy and decreased film microstrain. The corrosion behavior of ZrN/AZ91 samples in Ringer's solution was studied to evaluate corrosion potential and corrosion current density. Potentiodynamic corrosion tests showed that all ZrN-coated samples had a corrosion resistance superior to the blank substrate, mainly at 400 °C. A correlation was also established between vacancy defects in the film and corrosion behavior.

A Grade 4 titanium was processed by equal-channel angular pressing (ECAP)–Conform and drawing to produce an ultrafine grain (UFG) size of ~180 nm. Some samples were tested in this condition (UFG-1) and others were annealed for 1 h at 623 K (UFG-2). The grain boundaries are in a non-equilibrium condition after processing, but the annealing equilibrates the boundaries without any increase in grain size. This leads to significant differences in the mechanical behavior of UFG-1 and UFG-2 when they are tested at 293 and 623 K.

Epitaxial graphene of uniform thickness prepared on SiC is of great interest for various applications. On the Si-face, large area uniformity has been achieved, and there is a general consensus about the graphene properties. A similar uniformity has yet not been demonstrated on the C-face where the graphene has been claimed to be fundamentally different. A rotational disorder between adjacent graphene layers has been reported and suggested to explain why multilayer C-face graphene show the π-band characteristic of monolayer graphene. Utilizing low energy electron microscopy, x-ray photoelectron electron microscopy, low energy electron diffraction, and photoelectron spectroscopy, we investigated the properties of C-face graphene prepared by sublimation growth. We observe the formation of micrometer-sized crystallographic grains of multilayer graphene and no rotational disorder between adjacent layers within a grain. Adjacent grains are in general found to have different azimuthal orientations. Effects on C-face graphene by hydrogen treatment and Na exposure were also investigated and are reported. Why multilayer C-face graphene exhibits single layer electronic properties is still a puzzle, however.

Homogenous strontium titanate (SrTiO3) nanofibers were prepared via the electrospinning of precursor solutions containing both strontium and titanium salts. Photocatalytic activities of these SrTiO3 nanofibers for hydrogen generation from water were examined and compared to that of SrTiO3 nanoparticles. The nanofibers calcined at 700 °C showed the highest photocatalytic activity of 167 μmol/h/g among the SrTiO3 samples tested. The high activity was attributed to the ideal stoichiometric ratio of Ti/Sr, small crystallite size, high crystallinity, mesoporous structure, large surface area, and appropriate energy gap. These were confirmed through field emission scanning electron microscopic with energy dispersive spectroscopic observations, x-ray diffraction patterns, N2 gas absorption–desorption isotherm measurements, photoelectron yield spectroscopy in air, and UV-visible spectrophotometry.

This paper describes the mechanical properties under nanoindentation of a new glassy alloy with a nominal composition of Ni60Nb37B3, in the form of melt-spun ribbons and 1-mm-thick copper mold-cast sheets. The alloy composition was designed based on the synergy between the topological instability criterion and the difference in electronegativity among the elements. X-ray diffraction and scanning electron microscopy analyses confirmed that both ribbon and sheet samples possess totally amorphous structures with relatively high thermal stability (supercooled liquid region of about 60 K), as evaluated by differential scanning calorimetry (DSC). Nanoindentation tests revealed that the hardness of this alloy, about 15 GPa, is among the highest reported for metallic glasses. The elastic modulus of the cast sheet is higher and its hardness is similar to that of the ribbon. This correlates well with the different amounts of frozen-in free volume in both types of samples detected by DSC.