In the current manuscript we discuss the response of dynamic metallogels that display reversion to the liquid state when exposed to phosphines. The metallogels are formed through the condensation of formaldehyde and poly(alkyloxide)amines in polar aprotic solvents. The gel formation can be catalyzed with trivalent metals (Al(III and Fe(III)) with concomitant enhanced dynamism (gelation/degelation). When various phosphines are introduced, the metallogel is irreversibly liquefied. This process adds a new vector for controlling the bulk properties of this class of materials. Here, we explore the mechanism in detail for the reaction of tris(carboxyethyl)phosphine with N,N,N-triethoxylethyl-1,3,5-hexahydro-1,3,5-triazine (HEHT, 1) a stable derivative of the active hexahydrotriazine (HT) core in dimethylformamide in the presence or absence of Al(III). Additionally, density functional theory is used on the model N,N,N-trimethyl system (MHT, 2) to estimate reaction parameters and predict nuclear magnetic resonance spectra.

We analyze the effect of functionalization in the surface of zinc oxide crystal structure by 3-mercaptopropionic acid. X-ray powder diffraction data and extended x-ray absorption fine structure studies confirms a wurtzite structure. However, the morphology of the surface seems to be reduced and shows a film-like surface as demonstrated by x-ray absorption near edge structure and scanning electron microscopy. As a result of surface functionalization, the energy levels of the semiconductor were shifted toward reductive potentials (by 50 mV) as determined by diffuse reflectance and cyclic voltammetry.

Many studies have been carried out to thoroughly understand the colorization mechanisms of bird feathers. However, most of the methods used so far are time-consuming (in days) and involve rather complicated steps (5 to 12). Here, we report a rapid way of producing ‘PbS bird feathers’; this method is inspired by a hair-dyeing method used in ancient Egypt 4000 years ago. The complete synthesis route comprises only two steps and can be completed within 2 h, with the original morphologies of bird feathers well preserved. This method has potential to be extended to the fast fabrication of other functional sulfides which are too complicated to fabricate otherwise.

To investigate the manipulation of electromagnetic properties of two-dimensional materials, this effort characterizes charge transfer behavior of colloidal COF-5 (covalent organic framework) in the presence of various metal ions. A series of metal chloride compounds was introduced to COF-5 in solution and solid film phases and the interaction of the material with electromagnetic radiation was monitored across the visible region using electronic absorption spectroscopy. Notable changes were observed, quantified, and discussed for copper (II) chloride (CuCl2), chromium (III) chloride (CrCl3), and iron (III) chloride (FeCl3) with COF-5. Ligand-to-metal and metal-to-ligand charge transfer are explored as a possible mechanism for the observed electronic behaviors.

Geometrical features are known to be very important in neuronal growth and the formation of neuronal networks. We present an experimental and theoretical investigation of axonal growth and dynamics for neurons cultured on patterned polydimethylsiloxane surfaces. We utilize fluorescence microscopy to image the axonal dynamics and show that these substrates impart a strong directional bias to neuronal growth. We model axonal dynamics using a general stochastic model and use this framework to extract key dynamical parameters. These results provide novel insight into how geometrical cues influence neuronal growth and represent important advances toward bioengineering neuronal growth platforms.

Nanoporous Au shows the antimicrobial activity without the release of ROS. The cell wall is hyperpolarized by npAu. Hence, the hyperpolarized cell wall may affect ATP synthase, leading to the bacterial death. In the present work, the effects of the hyperpolarized cell wall on the structure and functions of Asp61 in ATP synthase are investigated by molecular dynamics simulations and first-principles calculations. The simulations suggest that the Asp61 is more negatively hyperpolarized, which is due to the strengthened O–H bond in Asp61, in interacting with the hyperpolarized cell wall, which results in the disturbance of proton transport in ATP synthase.

Perovskite materials are sensitive to environmental conditions. Here we report the synthesis and characterization of a hydrophobic alkylammonium lead(II) iodide perovskite with enhanced stability in water. Water stability was achieved by growing a shell of 4-[(N-3-butyne)carboxyamido]anilinium lead(II) iodide over methylammonium lead(II) iodide. As a proof of concept, the water-splitting reaction was performed using our new material coated on TiO2, and a 7-fold increase in applied bias photon-to-current efficiency was observed as compared with standard p25-TiO2. Such simple and versatile chemical modification to induce high water stability is useful toward exploring new applications for the perovskite materials.

Excitation of surface waves on conducting materials provides a near resistance-free interface capable of a material glissade either by plasmon forces or by optical beam tractors. Analogous to an ice hockey rink, as proof-of-principle plasmon-assisted optical traction, or hoovering, of water drops on a gold surface is demonstrated. Changes in the contact angle provide a novel, low-cost nanoscale method of quantifying observable and potentially tunable changes. Variability in thresholds and movement, including jumps, is observed and can be explained by the presence of significant roughness, measured by scanning electron microscopy, with water tension. The demonstration opens a path to directly integrate various optical and plasmonic traction technologies. Implications of the phenomena and ways of improving transport and potential applications spanning configurable microfluidics, antennas, tunable lenses, diagnostics, sensing, and active Kerr and other devices are discussed.

Material changes in yttrium-doped barium zirconate, BaZr0.8Y0.2O3–x, were studied using in situ Raman spectroscopy and ex situ x-ray photoelectron spectroscopy analysis. During in situ Raman analysis, samples were heated to temperatures of 300–600 °C and exposed to both dry and humidified H2 atmospheres. At the lower temperatures (300–450 °C), a new vibrational peak appears in the Raman spectra during exposure to humidified H2. The appearance of this feature is reversible, dependent on previous sample history, and possibly results from new, secondary phase formation or lattice distortion.

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.

Vertically aligned nitrogen-doped nanocrystalline diamond nanorods are fabricated from nitrogen-doped nanocrystalline diamond films using reactive ion etching in oxygen plasma. These nanorods show enhanced thermionic electron emission (TEE) characteristics, viz., a high current density of 12.0 mA/cm2 and a work function value of 4.5 eV with an applied voltage of 3 V at 923 K. The enhanced TEE characteristics of these nanorods are ascribed to the induction of nanographitic phases at the grain boundaries and the field penetration effect through the local field enhancement from nanorods owing to a high aspect ratio and an excellent field enhancement factor.

Development of biomaterials with primary amine surfaces is very important for the study of some cells of the immune systemuch as macrophages. Currently, the modification can be carried out by physical or chemical methods with several disadvantages due to the presence of additives or subproducts in the system. To overcome this problem, modified polypropylene (PP) films were synthesized by gamma radiation. In this work, radiation grafting of acryloyl chloride onto PP has been employed to form an acyl chloride. Then, the radiation-grafted films were reacted with ethylenediamine in several solvents to obtain the different concentration of the primary amine. The surface amine concentration was determined by derivatization with 4-trifluoromethyl benzaldehyde and characterized by x-ray photoelectron spectroscopy (N/C ratios), Fourier transform infrared spectroscopy with attenuated total reflection, contact angle, scanning electron microscopy, atomic force microscopy, and elementary analysis. The stability of the amines was measured up to 90 days, without the occurrence of aging as was found by plasma modification.

Waterproof bioelectrodes enable long-term biological monitoring and the assessment of performances of athletes in water. Existing gel electrodes change their electrical properties even when covered with a waterproof film. Here, the authors present the poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/poly(styrene-butadiene-styrene) (SBS) bi-layer nanosheet and waterproof film for a comfortable waterproof bioelectrode. PEDOT:PSS/SBS is fully foldable with a conductivity loss of only 5%. This foldable nanosheet electrode provides a reliable electrical connection between the skin and the wire. The waterproof film-covered bioelectrode enables continuous monitoring of electrocardiograms in water, showing a signal-to-noise ratio of 21.5 dB for the R wave and 17.5 dB for the T wave, comparable to atmospheric measurements, and sensing a change in heart rate from 79 to 131 bpm during bathing.

The extending market of concentrated solar power plants requires high-temperature materials for solar surface receivers that would ideally heat an air coolant beyond 1300 K. This work presents investigation on high-temperature alloys with ceramic coatings (AlN or SiC/AlN stacking) to combine the properties of the substrate (creep resistance, machinability) and coating (slow oxidation kinetics, high solar absorptivity). The first results showed that high-temperature oxidation resistance and optical properties of metallic alloys were improved by the different coatings. However, the fast thermal shocks led to high stress levels not compatible due to the differences in thermal expansion coefficients.

To improve the stability of Cs2SnCl6 under aqueous/moisture environments, we applied a concept of artificial passivation by depositing a protective TiO2 coating of 10 nm on the surface of Cs2SnCl6. Static leaching experiments results indicate that the initial release rates of Cs+ and Cl− are decreased by 20–30 times with TiO2 coating, suggesting its possibility to improve the short-term water/environmental stability of Cs2SnCl6. An amorphous-to-crystalline phase transition in TiO2 film was observed, possibly resulting in degradation of Cs2SnCl6. However, the crystalline TiO2 film still remains after 21 days water exposure and can still act as an effective passivation layer to reduce the release rates of Cs+ and Cl- by as much as about 17 and 7 times, respectively, relative to static leaching without artificial coatings. Therefore, the water/environmental stability of metal halide perovskite Cs2SnCl6, which is a highly soluble molecular salt, can be enhanced by the nanoscale TiO2 coating as an artificial passivation film.

Increasing fluorination of organosilyl nitrile solvents improves ionic conductivities of lithium salt electrolytes, resulting from higher values of salt dissociation. Ionic conductivities at 298 K range from 1.5 to 3.2 mS/cm for LiPF6 salt concentrations at 0.6 or 0.7 M. The authors also report on solvent blend electrolytes where the fluoroorganosilyl (FOS) nitrile solvent is mixed with ethylene carbonate and diethyl carbonate. Ionic conductivities of the FOS solvent/carbonate blend electrolytes increase achieving ionic conductivities at 298 K of 5.5–6.3 mS/cm and salt dissociation values ranging from 0.42 to 0.45. Salt dissociation generally decreases with increasing temperature.

We have investigated the feasibility of aerosol spray pyrolysis for the synthesis of copper sulfide nanocrystals, which are promising candidates for the development of low-cost, printable photovoltaic devices. A solution of copper diethyldithiocarbamate in toluene is aerosolized and aerodynamically dragged through a tube furnace, where the droplets are dried and nanocrystals are formed. Particles smaller than 20 nm are produced. The particles are preferentially formed as digenite (Cu1.8S), although we show that with low furnace temperature it is possible to produce chalcocite (Cu2S) nanocrystals.

We demonstrate that fluorescence properties of organic fluors embedded in a porous polystyrene matrix are highly sensitive to the average pore size and pore-size distribution of the matrix. The effect can be understood as two different types of confinement imposed to the fluor molecules by the matrix. First, there is geometrical confinement that restricts the fluor oscillations due to its physical contact with a pore wall. Second, there is an electronic confinement due to a local polarization of the wall material by molecular dipoles. The effects lead to a spectral shift and enhancement of the fluorescence intensity of the material.