Frequency-dependence and magnitude of second harmonic generation (SHG) from ~4 × 105 nm2 molybdenum disulfide (MoS2) monolayers was examined in presence of single 150 nm plasmonic gold@silica shell@core nanoantenna monomer and dimers. Quantitative agreement between discrete dipole approximation-calculated fields and measured SHG enhancements was found. SHG from MoS2 was enhanced up to 1.88 × upon deposition of a plasmonic nanoantenna-dimer with 170 nm gap, reaching maximal normalized SHG conversion efficiency of 0.0250%/W. Pump losses attributable to plasmonic damping, e.g., scattering and/or hot-electron injection into MoS2, were apparent. Linear and nonlinear optical activity of MoS2 and nanoantenna controls were compared with literature values.

The time-dependent pyramidal or conical indentation of viscoelastic–plastic materials, such as glassy polymers, is examined by a flexible, Kelvin-like model. The model equation is simply solved numerically for a wide range of material properties and indentation loading sequences. The flexibility of the model is demonstrated by generating typical indentation responses for a metal, a ceramic, an elastomer, and a glassy polymer. Polymer indentation is further examined under ramp, hold, and cyclic loading conditions, including adhesive effects. The model and approach should be particularly useful in identifying the various deformation components contributing to observed instrumented indentation phenomena.

The influence of the content of trifluoroacetate (TFA), in the precursor solution, on the critical current density (Jc) of YBa2Cu3O7−x (YBCO) superconducting films was investigated. We found that a TFA/Ba ratio of 0.68 is optimal to obtain high-performance YBCO films. Using this optimal solution, we then developed an ultraviolet (UV) light soaking technique to prepare YBCO films. This resulted in the constituent elements being uniformly distributed in the films, and this then enabled enhanced Jc. The addition of water vapor during the UV soaking process decreased the content of carbon residue in the films, and further increased the Jc of the resulting YBCO films.

In this work, using density functional theory we study electronic and atomic structure as well as redistribution of ions at the interface between cubic-Li7La3Zr2O12 (LLZO) (001) and LiCoO2 (LCO) (10–14). It is found that a large lattice-mismatch-induced compressive strain of ~12% at the interface leads to disordering of LLZO (001). However, even a large tensile strain of ~13.5% does not influence ordering of LCO (10–14). Li ions tend to move from the surface of LCO and bulk LLZO to occupy the interstitial sites at the topmost layers of the LLZO slab. Li ion transfer from LCO to LLZO accompanies with electron transfer from the former to the latter and the formation of gap states.

Binder-free three-dimensional Co3O4 electrodes are fabricated by an economical and scalable one-step flame combustion method, namely Reactive Spray Deposition Technology. The electrodes are composed of porous nanostructured Co3O4 uniformly distributed throughout the conductive substrate. In the absence of any further optimization on the processing conditions, the as-synthesized electrodes demonstrate high capacitance of 567 F g−1 at 1.5 A g−1, excellent rate capability, and stable cycling performance with a capacity retention ratio of 96.7% after 1000 charge/discharge cycles from the three-electrode half-cell testing. This study presents the pathway to a significantly simplified manufacturing process of three-dimensional electrodes with the desirable porous nanostructure.

The goal of this study was to perform in situ electrochemical polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT) in peripheral nerves to create a soft, precisely located injectable conductive polymer electrode for bi-directional communication. Intraneural PEDOT polymerization was performed to target both outer and inner fascicles via custom fabricated 3D printed cuff electrodes and monomer injection strategies using a combination electrode-cannula system. Electrochemistry, histology, and laser light sheet microscopy revealed the presence of PEDOT at specified locations inside of peripheral nerve. This work demonstrates the potential for using in situ PEDOT electrodeposition as an injectable electrode for recording and stimulation of peripheral nerves.

The selectivity of catalyst is an essential factor in direct methanol fuel cells (DMFCs) and plays an important role to improve their performance. To this end, platinum (Pt)-based low-cost trimetallic catalysts have been developed. The catalyst comprising ultra-low Pt-decorated NiCu bimetallic alloys nanoparticles fabricated on reduced graphene oxide (rGO). The series of Pt-NiCu/rGO nanocomposites were synthesized with different compositions to obtain the optimal conditioned material. The electrochemical results showed good performance for the electro-oxidation of methanol at anodic end of DMFCs. These outcomes opened up a broad avenue for developing lower cost-active catalysts with better performance for DMFCs.

Superparamagnetic iron oxide nanoparticles (SPIONPs) are successfully synthesized in this study by co-precipitation method using actinobacterial metabolites as reducing agent. Physicochemical and morphological features of the nanoparticles (NPs) are analyzed by Fourier-transform infrared spectroscopy, x-ray-based techniques, vibrating sample magnetometer, thermal gravimetric analysis, and electron microscopic analysis, with an average size of 15–30 nm. Anticancer activity of the magnetite-NPs is systematically evaluated on HeLa cells using MTT assay, Hoechst nuclear staining, acridine orange/ethidium bromide dual staining and flow cytometric analysis. The obtained results open a new route for biosynthesis of SPIONPs, which to be used for various biomedical applications, particularly in cancer therapy.

Three different hydrothermally grown carbonaceous materials and their molybdenum chalcogenides derived from glucose (HTC, HTC–MoO2, HTC–MoS2) were investigated to evaluate their potential as Li-ion battery anodes. All tested materials exhibited good cycling performance at a current density of 100 mA/g and showed high coulombic efficiency, >98%, after the 50th cycle. Reversible charge capacities of HTC, HTC–MoO2, and HTC–MoS2 were 296, 266, and 484 mAh/g, respectively, after 50 successive cycles. This study demonstrated that the HTC–MoS2 showed the highest reversible charge capacity which promises to be a good candidate for an environmentally friendly anode material for Li-ion batteries.

Lead halide perovskite solar cells (PSCs) with a structure of glass/FTO/TiO2/CH3NH3PbI3 with single-walled carbon nanotubes (SWNT) as the transparent top electrodes, followed by polymethyl methacrylate (PMMA) over-coating were fabricated. The SWNT-based PSCs do not require expensive metal electrodes and hole-transporting materials yet produce a decent power conversion efficiency of 11.8%, owing to the densifying effect of SWNTs by PMMA. The resulting devices demonstrate reduced hysteresis, improved stability, and increased power conversion efficiency.

We investigate the two-photon absorption characteristics of hemicyanine dyes that exhibit a one-photon absorption at around 500 nm. The dyes exhibited two-photon-induced fluorescence upon irradiation with an Yb-doped femtosecond fiber laser operating at 1030 nm. Among the dyes, 4-[4-[4-(dimethylamino)phenyl]-1,3-butadienyl]-1-ethyl-pyridinium perchlorate exhibited the most efficient two-photon-induced fluorescence at 1030 nm. Since these dyes possess cationic moiety, the dyes accumulated in the mitochondria of a living cell. Two-photon images of mitochondria were obtained by staining living HEK293 cells with these dyes. When 4-[4-[4-(dimethylamino)phenyl]-1,3-butadienyl]-1-ethyl-pyridinium perchlorate was employed, a two-photon-induced fluorescence image could be obtained even when a 3 mW fiber laser beam was used as the excitation source.

The present work focuses on the radiation-modification of chitosan (CS) with N,N-dimethylacrylamide (DMAAm) presented as three different architectures: comb-type grafting hydrogels (net-CS)-g-DMAAm, interpenetrating networks of CS and DMAAm (net-CS)-inter-(net-DMAAm), and semi-interpenetrating networks (net-DMAAm)-inter-CS. The syntheses of different polymeric architectures were realized by gamma irradiation by a 60Co source. The optimum conditions for the syntheses of the three systems were at a dose of 6 kGy. Only the comb-type system presented a well-defined critical pH. All the hydrogels showed porous and interconnected structures according to scanning electronic microscopy. These different architectures could be used as three-dimensional cell culture scaffolding.

The use of copper hydroxyphosphate (Cu2PO4OH), also called libethenite, as a near-infrared (NIR) absorbing additive has been investigated. Samples were synthesized by using a hydrothermal treatment or simple wet chemical processing, which was later easily upscaled. All synthesized samples showed a strong absorption in the NIR region. Trials were conducted to produce laser-marked plastic plates and security IR ink printing tests. It was found that when incorporated in plastic and ink formulation, Cu2PO4OH added good NIR absorption properties without influencing other finished product properties too much, which confirms that it is a suitable additive that can be readily manufactured at room temperature and without pressured equipment.

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.

We report an epitaxy growth and characterization of InAs photodetector (PD) on virtual Ge/Si and GaP/Si substrates. The effect of different types of the virtual substrate on the structure and performance of the InAs PD was studied. Although the lattice mismatch between InAs and Si is large (11.6%), close to 100% relaxation of InAs was achieved on both virtual substrates. A higher surface roughness was observed in the InAs layer grown GaP/Si as compared with that of Ge/Si. InAs PD with room temperature blackbody specific detectivity of ~5 × 108 cm·Hz1/2/W is achieved in photovoltaic mode on both types of virtual substrate.

We show that the optical response of ultrathin metallic films of finite lateral size and thickness can feature peculiar magneto-optical effects resulting from the spatial confinement of the electron motion. In particular, the frequency dependence of the magnetic permeability of the film exhibits a sharp resonance structure shifting to the red as the film aspect ratio increases. The films can also be negatively refractive in the IR frequency range under proper tuning. We show that these magneto-optical properties can be controlled by adjusting the film chemical composition, plasmonic material quality, the aspect ratio, and the surroundings of the film.

Melt electrospinning is a facile fabrication technique that can be utilized in the creation of microfibers without the use of solvent and with good control over feature placement. The available thermal energy of the melt electrospinning technique is often only utilized in the formation of the polymer melt but can also be used to thermodynamically drive chemical reactions. In this study, hybrid perovskite microcrystallites are synthesized in the polymer melt and electrospun to form composite microfibers. Unique hybrid perovskite microstructures were studied, elucidating mechanisms of formation at work in the polymer melt.