Nitric acid oxidation at various concentrations was used to change the surface chemistry of activated carbon fiber (ACF). Boehm titration, zeta potential results confirmed the presence of acidic functional groups on the surface of ACF. Physicochemical characterizations verified the growth of zinc oxide (ZnO) on surface-oxidized fiber. ZnO/ACF rods and flowers formed at pH 7 and 9 were used for decontamination of malathion at solution pH in the presence of ultrasonic waves and ultraviolet radiations. The disappearance of malathion in the solution followed pseudo-first-order kinetics. Total organic carbon analysis confirmed the decontamination of malathion in aqueous media.

We report on a new type of polymer electrolyte fuel cell based on a hydroxide ion conductive polymer combined with a non-noble chromium–nickel (Cr–Ni) catalyst for the oxygen reduction reaction (ORR). We study variable fractions of Cr in Ni by density functional theory simulating the thermodynamic potentials characterizing the ORR. We found increased ORR catalytic activity employing the rotating disk electrode technique. The polarization curve and power densities measured for the constructed fuel cell indicate considerable performance improvement with the Cr–Ni catalyst. Thus we expect that this kind of fuel cell may open up alternative routes in fuel cell research using non-noble catalysts.

This work focuses on the syntheses of Zn-enriched PtZn nanoparticle electrocatalysts by solution combustion for ethanol oxidation reaction (EOR). Analytical techniques of x-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy, TEM/scanning TEM-energy dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy are used for the characterization of electrocatalysts. Cyclic voltammetry and chronoamperometry are applied for the electrocatalysis of C2H5OH and stability test in an alkaline medium, respectively. Electrochemical data show that PtZn/C has improved electrocatalytic activity by ~2.3 times compared with commercial Pt/C, in addition to having earlier onset potential and better stability for EOR. The variation of fuel amount in the synthesis has affected crystallite sizes, electronic, and electrochemical properties in electrocatalysts.

This work presents a study of the region of nanoparticle growth in an atmospheric pressure carbon arc. The nanoparticles are detected using the planar laser-induced incandescence technique. The measurements revealed large clouds of nanoparticles in the arc periphery bordering the region with a high density of diatomic carbon molecules. Two-dimensional computational fluid dynamic simulations of the arc combined with thermodynamic modeling show that this is due to the interplay of the condensation of carbon molecular species and the convection flow pattern. These results show that the nanoparticles are formed in the colder, peripheral regions of the arc and describe the parameters necessary for coagulation.

The goal of this work was to provide antimicrobial activity to polypropylene by covalent immobilization of lysozyme. The first step was the grafting of ethylene glycol dimethacrylate and glycidyl methacrylate through “grafting-from” method by means of γ-rays. Then those chemical groups were activated to allow the immobilization of lysozyme by Schiff bases. The activity of lysozyme showed an improvement by the remaining double bonds from the grafting. Finally, the presence of lysozyme was confirmed by the hydrolysis of Micrococcus lysodeikticus at different temperatures, pH values, and cycles. The new materials were characterized by infrared spectroscopy, thermal analysis, contact angle, and by the surface morphology.

Kinetic Monte Carlo (KMC) models of complex materials and biomolecules are increasingly being constructed using molecular dynamics (MD). A KMC model contains a catalog of states and kinetic pathways, which enables study of the dynamics. The completeness of the catalog is crucial to the model accuracy and is linked to the quality of the MD data used for model construction. Therefore, quantifying the uncertainty due to missing states and pathways is important. A review on computational procedures available for on-the-fly KMC model construction using MD, uncertainty measurement, and algorithms for guiding further MD sampling in an accelerated manner is presented.

We report fabrication of 200 mm silicon (Si)-wafer mold structure for polydimethylsiloxane (PDMS) microfluidic devices to demonstrate a real-time fluorescence imaging of single DNA molecules. Conventional photolithography with deep reactive ion etching process allows us to build a “mesa”-type Si mold with a nanoscallop sidewall geometry aiding PDMS residue-free process. By optimizing fluorescence microscopy with the fabricated PDMS chamber, we obtain a protocol to visualize the motions of single DNA molecules. This integrative PDMS-based single-molecule imaging system can, in principle, be used as a platform to study biochemical reactions occurring in proteins, nucleotides, and vesicles.

A new phase of carbon named Q-carbon is found to be over 40% harder than diamond. This phase is formed by nanosecond laser melting of amorphous carbon and rapid quenching from the super-undercooled state. Closely packed atoms in molten metallic carbon are quenched into Q-carbon with 80–85% sp3 and the rest sp2. The number density of atoms in Q-carbon can vary from 40% to 60% higher than diamond cubic lattice, as the tetrahedra packing efficiency increases from 70% to 80%. Using this semiempirical approach, the corresponding increase in Q-carbon hardness is estimated to vary from 48% to 70% compared to diamond.

ZnO-based oxides are promising for thermoelectric energy generation at elevated temperatures. We study electrical transport properties of Ni-doped ZnO applying the density functional theory, indicating increase of the electrical conductivity (σ) and decrease of the Seebeck coefficient (S) due to Ni-doping, in full accordance with experimental results. We calculate the temperature-dependent σ and S applying the Boltzmann transport theory, approximating the electron relaxation time, τe. Good agreement with experimental data is obtained considering both temperature and energy dependence of τe. This yields explicit expressions for τe and provides us with powerful predictive tool assessing electronic transport in ZnO.

We have performed mechanical finishing operations on Sverker 21 (traditional) and Vanadis 6 (advanced powder) steel surfaces: grinding, turning, and turning followed by slide burnishing. Then each specimen was subjected in turn to focused ion beams of helium or krypton up to fluences of 1015 ions/cm2 and finally to scratch resistance testing. Acoustic signals show that krypton implantation reduces microcracks. Helium ions act even more strongly as homogenizers—almost completely eliminating the imperfections. Optical microscopy during scratch testing shows the force level when debris formation begins. Helium ions fitting between the iron atoms increase the resistance against scratching; larger krypton ions produce the opposite effect.

Epitaxial Sm0.6Nd0.4NiO3 thin films were grown on different substrates by pulsed laser deposition. X-ray diffraction indicates that for SLAO substrate, strain relaxation is accompanied by the creation of oxygen vacancies. The film resistivity on LaAlO3 and SrTiO3 substrates shows a clear insulator–metal transition (IMT) at 185 and 325 K, respectively, while the film is exclusively semiconducting on SrLaAlO4. At low temperatures, the conductivity of films deposited on SrLaAlO4 and SrTiO3 is described by the Mott variable-range hopping mechanism. With increasing film thickness, progressive tensile strain relaxation takes place, which in turn results in a gradual decrease in the IMT temperature.

Robust evidences are presented showing that the Raman mode around 250 cm−1 in the Sb2Se3 thin films does not belong to this binary compound. The laser power density dependence of the Raman spectrum revealed the formation of Sb2O3 for high values of laser intensity power density excitation under normal atmospheric conditions. To complement this study, the Sb2Se3 films were characterized by x-ray diffraction during in situ annealing. Both these measurements showed that the Sb2Se3 compound can be replaced by Sb2O3. A heat-assisted chemical process explains these findings. Furthermore, Raman conditions required to perform precise measurements are described.

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.

Germanium is a small-gap semiconductor that efficiently absorbs visible light, resulting in photoexcited electrons predicted to be sufficiently energetic to reduce H2O for H2 gas evolution. In order to protect the surface from corrosion and prevent surface charge recombination in contact with aqueous pH 7 electrolyte, we grew epitaxial SrTiO3 layers of different thicknesses on p-Ge (001) surfaces. Four-nanometer SrTiO3 allows photogenerated electrons to reach the surface and evolve H2 gas, while 13 nm SrTiO3 blocks these electrons. Ambient pressure x-ray photoelectron spectroscopy indicates that the surface readily dissociates H2O to form OH species, which may impact surface band bending.

By inserting a carbon chain, the geometric structure and electronic properties of carbon nanotube (CNT) would undergo a significant change. Numerous studies have conducted to experimentally find the insertion effect of carbon chains on CNTs. This paper in a theoretical way studied the geometry of carbon chains inserted CNTs and analyzed the mechanism for conductivity change after insertion of carbon chains. Results indicate that carbon chains in the innermost channel of the tube are effective methods for transforming the electrical properties of the CNT, leading to the redistribution of electron and thereby causing the conductivity change in obtained configurations.

We investigate the impact of increasing number density of self-catalyzed GaAs nanowires (NWs) on their crystal structure, grown by molecular beam epitaxy. To this end, we employ an iterative, lithography-free approach for varying the number density of self-catalyzed GaAs NWs grown on Si(111) covered with native oxide. We use scanning electron microscopy and x-ray diffraction in combination with simulations based on the extended Markov model for the morphologic characterization of the so obtained NWs. Our findings show how both the shape of the Ga-droplet and the NW crystal structure are affected even by relatively small changes of the wire number density, allowing for a quantification of its influence on the local NW growth conditions at nominally identical growth parameters.

Perovskites solar cells have reached impressive efficiencies (22%) in recent years. Because certain environmental concerns are raised by the use of lead halides, there is an interest to seek out lead-free alternatives, featuring bismuth or antimony. Alongside, one of the major drawbacks displayed by MAPbI3 is their low stability at ambient conditions. In this work, (RP4)xBiyIz were synthesized, using different types of tetra-alkylphosphoniums (R4PI) were R = ethyl, butyl, hexyl, and octyl, to assess their stability. Afterwards, they were characterized to study their morphology and crystal structure, as well as their optical properties.

In this paper, a single-band local surface plasmon mode resonance metamaterial filter is calculated and simulated. The damping constant of the gold film is optimized in simulations to eliminate the effects of the grain boundary and the surface scattering on the transmission property. The transmission property of the designed metamaterial filter can be enhanced through optimizing structural parameters (the vertical distance or radius of the gold particle). Two narrow transmission bands are achieved due to the electric field enhancement effect. The electric field enhancement factor η = |E|/|E 0| is used to reveal the electric field resonance strength change. Higher transmission peak and larger field enhancement factor can be achieved than the pure gold hole array structure.

Diamond stands out in its ability to host hundreds of color centers, the most studied of which may be the nitrogen-vacancy and NE8 centers. The NE8 center, in particular, can generate single photons at an energy of 1.56 eV, but synthesis efforts are low yield and lack precise control of the defect structure and resulting optical properties. Complementing a bottom-up synthesis effort, we develop a rapid-screening computational approach for screening potential color centers in nanodiamond, focusing here on the nickel–nitrogen complexes. Formation and optical absorption energies are characterized with respect to defect stoichiometry and structure.

The goal of this work was the modification of silicone rubber (SR) by radiation grafting of glycerol methacrylate (GlyMA) which was limited just on the surface, allowing the control of hydrophilicity and swelling properties. The grafted SRs were activated by derivatization of GlyMA to 2-oxoethyl methacrylate using sodium periodate, enabling the chemical immobilization of lysozyme by covalent bonds. The presence of lysozyme was confirmed by non-specific assay and by the enzymatic activity at 30 °C with Micrococcus lysodeikticus (coccus, Gram-positive). The materials were characterized by Fourier transform infrared spectroscopy-attenuated total reflectance, thermogravimetric analysis, water contact angle, and by mechanical properties as well as scanning electron microscope.