The authors report the microwave-assisted hydrothermal synthesis of α-La(IO3)3 nanocrystals doped with Yb3+ and Er3+ ions, along with their structural and optical characterizations. 50-nm-sized α-La0.9−xYb0.1Erx(IO3)3 nanocrystals with x = 0.005, 0.01, and 0.02 were synthesized and dispersed in ethylene glycol. The as-obtained suspensions exhibit both second harmonic generation (SHG) signal and up-conversion photoluminescence (UC-PL) without interplay between the two signals under near-infrared resonant excitation. The relative intensity of SHG and UC-PL emission can be modulated according to the excitation wavelength. The most intense UC-PL signal is obtained from a 980-nm excitation, thanks to the sensitization of Er3+ by Yb3+.

A hybrid graphene–gold nanomesh, realized through Au deposition on a patterned graphene nanomesh with a focused ion beam, is introduced and illustrated for enhanced light absorption in the visible spectrum. Numerical studies reveal that the hybrid nanomesh with dual resonances in the visible spectrum exhibit ~50% light absorption and enhancement factor as high as ~1 × 108. The simulations also show that the enhanced optical absorption is associated with the excitation of surface plasmons. This is confirmed through the localization of electric fields at the resonant wavelengths. Such a hybrid graphene–gold nanomesh exhibiting enhanced light-matter interactions paves the way toward plasmonics, surface-enhanced Raman scattering applications, etc.

The structure of polymer networks in hydrogels determines the properties. In this study, we investigated the structure of a charge-balanced polyampholyte, poly(4-vinylbenzenesulfonate-co-[3-(methacryloylamino) propyl] trimethylammonium chloride). From as-prepared samples, nanoscale globules were visualized in polyampholyte hydrogels for the first time. The impact of dialyses processes on polymer structures were also studied. In deionized water, salt ions are leached out, thus polymer chains undergo zipping process to form cellular structure with micrometer-thick polymer walls that allow mechanical toughness to the hydrogel. Samples dialyzed in 6 M potassium hydroxide solution did not show such cellular structure, as in the case of as-prepared samples.

Powerful synergies between phosphonate, zinc oxide, and acrylamido-tert-butyl-sulfonate (ATBS) copolymer chemical additives render superior performance in a high-temperature retarder system for oil well grade Portland cement. The phosphonate retarder and ATBS-based retarders establish a two-tiered strength development where amorphous C-S-H converts to crystalline dicalcium silicate hydrate (C2SH) in the first (low compressive strength) tier prior to the reaction of Portlandite with quartz. The three additive retarder system can be tuned with nanosilica to eliminate the two-tiered strength development effect leading to a smooth transition from the cement in the slurry form directly to its highest compressive strength.

The hydrobaric effect on photoactivity of titanium dioxide (TiO2) fabricated by cathodic deposition in an aqueous solution was evaluated in this study. When the applied pressure was increased to 35 MPa, the water-splitting performance was improved by almost fourfold of the performance of the TiO2 prepared at atmospheric pressure. The surface states effect was significant in the deposited TiO2, which was exploited to affect the charges recombination of TiO2, and thereby enhance the resultant photoelectrochemical water-splitting performance. The hydrobaric cathodic deposition could be extended to fabrication of other metal oxides to eliminate the negative influence from the high-temperature process.

Significant α-phase growth confinement in Grade 4 titanium (Ti) and substantial β-phase refinement in Grade 7 Ti were observed during high-temperature annealing. The mechanism for each observation was identified through detailed microstructural investigation assisted with phase diagram analyses. The former observation was due to the pinning effect of Fe-stabilized grain boundary (GB) β-Ti phases in Grade 4 Ti. The latter observation resulted from the redistribution of Fe and, palladium (Pd) in particular, in Fe-stabilized and Pd-containing GB β-Ti phases in Grade 7 Ti. Pd was found to exist mainly in two forms in cold-rolled Grade 7 Ti, i.e. Fe-stabilized GB β-Ti phases and an occasionally observed orthorhombic Ti88Pd9Fe3 phase. The latter is close to the Ti2Pd3 intermetallic phase in terms of the crystal structure.

Magnetic nanoparticles have many potential applications in therapeutics and drug delivery. Heating by magnetic nanoparticles for hyperthermia application has gained tremendous popularity as a non-invasive treatment for tumor ablation. The heating effect of magnetic nanoparticles at different concentrations (1–10 wt%) in the fluid is investigated by varying the alternating magnetic field (60–260 Oe). The observed temperature rise (ΔT) shows an unusual increase with applied field in a higher nanoparticle concentration. In contrast to the previous model, the present study shows that temperature rise is more rapid in the higher particle concentration (~10 wt%) and low applied field (<125 Oe), and ΔT varies as H3/2 instead of H2.

A non-precious metal catalytic system of Fe-doped Ta2O5 is developed by pulsed laser deposition toward efficient oxygen evolution reaction (OER). The optimal Fe concentration is determined to be 5 at.% for optimized OER activity via a series of electrochemical characterizations. The 5 at.% Fe-doped Ta2O5 nanolayer possesses a low onset overpotential of 0.22 V, an overpotential of 0.38 V at 10 mA/cm2 and a Tafel slope of 54 mV/dec. Comprehensive first-principles calculations attribute the enhanced OER activity to the substitutional FeTa dopants, which generate a new active OER site on surface and simultaneously accelerate electron transfer over oxygens.

In this study, we performed computational simulations to extend the behavior knowledge over molecular systems composed by amylose oligomers, three fatty acids often found in Brazilian vegetable oils, water solvent, and montmorillonite. The focus is directed to the molecular movement and to intra and intermolecular interactions, each simulation step being compared with the literature's experimental profile. The calculations were mostly performed by Molecular Mechanics and Dynamics methods. The excellent agreement and complementarities with the literature results indicate, once again, the important contribution offered by the computational simulations to the design of new polymer–clay nanocomposites with biopolymers.

Using in situ indentation, we show that highly localized and well-defined mechanical deformation can be coupled with structural and electronic characterization in the scanning tunneling microscope. Dislocations induced in Ni(100) were topographically imaged and probed by scanning tunneling spectroscopy to assess their effect on local surface electronic structure. Compared with undamaged terraces, dislocation regions exhibited a significant increase in local density of states near the Fermi level, and enhanced reactivity toward oxidation. In the context of the d-band electronic structure model, we suggest that the undercoordination of atoms and residual strain resulting from plastic deformation serve to locally accelerate adsorption-driven chemical reactions with species such as molecular oxygen.

CuInS2 (CIS) quantum dots (QDs) with different diameters were prepared and their optical properties were studied. The optical band gap of QDs, as estimated by absorption spectrum, was found to decrease with increase in size. The stokes shift between absorption and photoluminescence peaks was observed to be larger (>100 meV) in all the three samples. This shows that the defect states available in the forbidden gap dominates the recombination mechanism. The variation in the emission peak with QD size, however, indicates that the relaxation dynamics in CIS QDs involves both excitonic level as well as the defect states.

In this paper, a simple evolution equation for dislocation densities moving on a slip plane is proven. This equation gives the time evolution of dislocation density at a general field point on the slip plane, due to the approach of new dislocations and tilting of dislocations already at the field point. This equation is fully consistent with Acharya's evolution equation and Hochrainer et al.’s “continuous dislocation dynamics” (CDD) theory. However, it is shown that the variable of dislocation curvature in CDD is unnecessary if one considers one-dimensional flux divergence along the dislocation velocity direction.

The present work demonstrates controllable directive radiation of a dipolar emitter coupled to a substrate-supported dielectric nanowire antenna. Nanoactuators, transparent-conducting oxides, and graphene are integrated into the substrate, respectively, to establish tunable antenna platforms in visible, near-infrared (IR), and far-IR frequency regimes. We exploit the substrate-induced interference effects and tunability mechanisms in each antenna system to achieve directive radiation with real-time steering capability. The design and modeling are rigorously carried out using an efficient and accurate semi-analytical framework based on transition matrix formulation. Each configuration is optimized to achieve maximal steering range while attaining a proper gain. Owing to subwavelength footprint, enhanced directionality, real-time tunability, and fairly simple geometry, the proposed platforms are ideal candidates for nanoantenna synthesis.

In many materials development projects, scientists and research heads make decisions to guide the project direction. For example, scientists may decide which processing steps to use, what elements to include in their material selection, or from what suppliers to source their materials. Research heads may decide whether to invest development effort in reducing the environmental impact or production cost of a material. When making these decisions, it would be helpful to know how those decisions affect the achievable performance of the materials under consideration. Often, these decisions are complicated by trade-offs in performance between competing properties. This paper presents an approach for visualizing and evaluating design spaces, where a design space is defined as the set of possible materials under consideration given specified constraints. This design space visualization approach is applied to two case studies with environmental impact motivations: one in biodegradability for solvents, and the other in sustainable materials sourcing for Li-ion batteries. The results demonstrate how this visualization approach can enable data-driven, quantitative decisions for project direction.

Monotonic and cyclic tension–tension tests with an upper stress in the GPa regime have been performed on Cu–Si nanowires. The results show that the exceptional high strength of these nanomaterials is maintained or even improved upon cyclic loading. Post-mortem transmission electron microscopy gives insight in the microstructural evolution. Fatigue-induced grain growth correlates with an observed increase in compliance, the formation of dislocation networks, and an increase in tensile strength.

Rational design of bio-hybrid photovoltaic and/or optoelectronic devices requires systematic electrochemical characterizations of photosystem I (PSI), the photosynthetic membrane protein, assembled onto tailored biotic–abiotic interfaces. This work communicates our research findings on the role of PSI microenvironment alterations at organic/inorganic interfaces, via biomimetic lipid membrane confinements and plasmonic coupling with Ag nano-pyramid structures, in tuning the photoactivated charge separation and photocurrent generations from surface-assembled PSI. The observed photocurrent enhancements and the associated mechanistic insights from this study will facilitate the future design of tailored interfaces that can optimally tune the photoactivity and photostability of PSI in solid-state bioelectronics.

This work investigates the influence of poly(dimethylsiloxane) (PDMS) within a nanocomposite coating solution constituted by silica nanoparticles and toluene on mechanical properties, surface wettability, and surface morphology. The developed coating's hardness and elastic modulus were studied in detail. A variation in mechanical properties was observed as the amount of PDMS was varied. Also, the average surface roughness, skewness, and kurtosis values show the influence of the amount of PDMS on the surface roughness characteristics of the coating. Furthermore, it was observed that the water contact angles were linked with the proportion of PDMS.

We report on reliability testing of vertical GaN (v-GaN) devices under continuous switching conditions of 500, 750, and 1000 V. Using a modified double-pulse test circuit, we evaluate 1200 V-rated v-GaN PiN diodes fabricated by Avogy. Forward current–voltage characteristics do not change over the stress period. Under the reverse bias, the devices exhibit an initial rise in leakage current, followed by a slower rate of increase with further stress. The leakage recovers after a day's relaxation which suggests that trapping of carriers in deep states is responsible. Overall, we found the devices to be robust over the range of conditions tested.

The fire-retardant and water-repellent bio-structural panels (BISPs) were successfully developed using cellulose nanofibrils, corn starch, boric acid, and n-dodecenyl succinic anhydride with adhesive-free character. Its performance properties were evaluated and compared with other well-known products on the market. The BISP's density (0.1 g/cm3) and permeance value [41.81 g/day/m2 with 5.76% coefficient of variation (CV)] were found higher than compared competitor products. The BISPs' contact angle was found 132.13° (1.59% CV) for BISP. The BISP was the only fire-retardant product, and the only one developed almost no smoke 2.20%.

The dendrite morphologies of the cast nickel-based superalloy CMSX-4® (CMSX-4® is registered trademarks of the Cannon-Muskegon Corporation) and the austenitic stainless steel HP microalloy have been obtained via an automated serial-sectioning process which allows three-dimensional (3D) microstructural characterization. The dendrite arm spacing, volume fraction of segregation, and fraction of porosity have been determined. This technique not only increases the depth, scope, and level of detailed microstructural characterization but also delivers microstructural data for modeling and simulation.