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Natural systems displaying optical properties have for long been an inspiration for new classes of optical constructs. Using the same families of materials employed by Nature in combination with their directed assembly allows access to n-dimensions of control to, ultimately, generate optical systems with multiple coexisting functions. This review provides an overview of lab-made optical systems made of protein and polysaccharide-derived materials found in naturally occurring optical systems. Recent advances in optical biomimicry and bioinspired, polyfunctional optical structures are presented, addressing attributes such as sensing, edible devices, biologically activity, and resorbable optical formats.
Because of their structural versatility, fast redox reactivity, high storage capacity, sustainability, and environmental friendliness, soluble organic redox molecules have emerged as materials that have potential for use in energy-storage systems. Considering these advantages, this paper reviews recent progress in implementing such materials in aqueous soluble organic redox flow batteries and organic alkali metal/air batteries. We identify and discuss major challenges associated with molecular structures, cell configurations, and electrochemical parameters. Hopefully, we provide a general guidance for the future development of soluble organic redox materials for emerging energy-storage devices used in the electricity grid.
This report is on the synthesis by electrospinning of multiferroic core-shell nanofibers of strontium hexaferrite and lead zirconate titanate or barium titanate and studies on magneto-electric (ME) coupling. Fibers with well-defined core–shell structures showed the order parameters in agreement with values for nanostructures. The strength of ME coupling measured by the magnetic field-induced polarization showed the fractional change in the remnant polarization as high as 21%. The ME voltage coefficient in H-assembled films showed the strong ME response for the zero magnetic bias field. Follow-up studies and potential avenues for enhancing the strength of ME coupling in the core–shell nanofibers are discussed.
Contact guidance is vital to many physiological processes, yet is still poorly understood. This is partly due to the variability of experimental platforms, making comparisons difficult. To combat this, a multiplexed approach was used to fabricate topographical cues on single quartz coverslips for high-throughput screening. Furthermore, this method offers control of surface roughness and protein adsorption characterization, two critical aspects to the in vitro environment often overlooked in contact guidance platforms. The quartz surface can be regenerated, is compatible with versatile microscopy modes, and can scale up for manufacturing offering a novel platform that could serve as a potential standard assay.
Five Au complexes are evaluated for the reduction reaction of CO2 via cyclic voltammetry and in a photocatalytic system. Electrochemically, the complexes were all evaluated for pre-association with CO2 prior to electrochemical reduction and for thermodynamic favorability for CO2 reduction in photocatalytic systems. The complexes were evaluated in photocatalytic reactions using an Ir-based photosensitizer and a sacrificial electron donor for the conversion of CO2 to CO. Au-complex counterion effects on the photocatalytic reaction were analyzed by varying weakly coordinating counterions with significant performance changes noted. At low Au-complex concentrations, a high TON value of 700 was observed.
The generalized gradient approximation (GGA) often fails to correctly describe the electronic structure and thermochemistry of transition metal oxides and is commonly improved using an inexpensive correction term with a scaling parameter U. The authors tune U to reproduce experimental vanadium oxide redox energetics with a localized basis and a GGA functional. The value for U is found to be significantly lower than what is generally reported with plane-wave bases, with the uncorrected GGA results being already in reasonable agreement with experiments. This computational set-up is used to calculate interstitial and substitutional insertion energies of main group metals in vanadium pentoxide and interstitial doping is found to be thermodynamically favored.
Engineering of thermoelectric materials requires an understanding of thermal conduction by lattice and electronic degrees of freedom. Filled skutterudites denote a large family of materials suitable for thermoelectric applications where reduced lattice thermal conduction attributed to localized low-frequency vibrations (rattling) of filler cations inside large cages of the structure. In this work, a multi-wavelength method of exploiting x-ray dynamical diffraction in single crystals of CeFe4P12 is presented and applied to resolve the atomic amplitudes of vibrations. The results suggest that the vibrational dynamics of the whole filler-cage system is the actual active mechanism behind the optimization of thermoelectric properties.
Here, the authors report a detailed method of growing LaAlGe, a nonmagnetic Weyl semimetal, thin film on silicon(100) substrates by molecular beam epitaxy and their structural and electrical characterizations. About 50-nm-thick LaAlGe films were deposited and annealed for 16 h in situ at a temperature of 793 K. As-grown high-quality films showed uniform surface topography and near ideal stoichiometry with a body-centered tetragonal crystal structure. Temperature-dependent longitudinal resistivity can be understood with dominant interband s–d electron–phonon scattering in the temperature range of 5–40 K. Hall measurements confirmed the semimetallic nature of the films with an electron-dominated charge carrier density of ~7.15 × 1021 cm−3 at 5 K.
Impedance spectroscopy was conducted on colloidal ITO thin films that had been subjected to alternating oxygen and argon plasma treatments, followed by air annealing from 150 to 750 °C. An equivalent circuit consisting of an RC element nested within another RC element, featuring a negative resistance and a negative capacitance, fitted the data well. These results are interpreted as being due to surface plasmons that are a function of the presence of nanoporous ITO-rich regions surrounded by isolated ITO nanoparticles coated with an amorphous polymer that intertwines with the ITO-rich regions as a function of annealing treatment.
The authors demonstrate that multicomponent metallic alloy nanofoams can be synthesized by the polymeric templating method. The present approach enabled alloy compositions not accessible via commonly used dealloying or co-deposition methods. The authors report the synthesis of a Cu50Ni50 alloy nanofoam using electrospinning polymeric templating, which exhibits distinct polycrystallinity, process-driven segregation, and enhanced mechanical strength over pure Cu nanofoams. Transmission electron microscopy revealed microscopic grain formation and their variable compositions. The processing method is applicable to the synthesis of a wide range of multicomponent metal porous materials, creating new research opportunities for noble alloy foams not available through wet electrochemical routes.
The stiffness of conjugated polymers should lead to chain alignment near buried interfaces, even if the polymer film is nominally amorphous. Although simulations predict that this alignment layer is approximately 1.5 times the persistence length, chain alignment at buried interfaces of amorphous polymers has not been experimentally measured. Using Mueller matrix spectroscopy, the optical response of regiorandom poly(3-hexylthiophene-2,5-diyl) (P3HT) was modeled in order to extract the aligned layer thickness. By approximating the optical properties of the aligned layer as that of regioregular P3HT, the data can be effectively modeled. When the film is thicker than 150 nm, optical properties are best described with a 4-nm aligned layer, which is quantitatively consistent with previous predictions.
This work studies phase-separated fibers in the CaO–SiO2 and NiO–SiO2 systems. The nature of the phase-separated microstructures and underlying phase equilibria are discussed, including dimensionality, composition, and phase formation as well as the realization of ferrimagnetic behavior in the NiO–SiO2 fibers based on the formation of metallic Ni inclusions. In addition to understanding the composition/processing relationships in these systems, the work represents a step forward toward novel magneto-optic fibers. It is important to understand the underlying materials science in order to advance the properties of novel optical fibers possessing engineered heterogeneities in the core.
In this work, a facile superhydrophobic coating for 2024-T3 aluminum alloy is developed and characterized. The corrosion resistance of the coating was analyzed. The results showed that the coating has high polarization resistance and a low corrosion rate. Furthermore, a micro/nanoscale investigation about the interaction between substrates and the corrosive environment was carried out using the in situ atomic force microscope technique. The change in surface topography was monitored for both the bare aluminum alloy substrate and the superhydrophobic aluminum alloy. The results showed that the coating retained surface features indicated that the coating has excellent corrosion resistance.
The incorporation of small amounts of phenolic antioxidants, such as 2,6-di-tert-butyl-4-cresol and pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], into photovoltaic organo-lead halide perovskite layers significantly suppressed the degradation of the perovskite compounds via light irradiation in the presence of ambient oxygen. While the facile incorporation of the antioxidants did not decrease both the quality of the formed perovskite crystal grains and the photovoltaic conversion performance of the cells, it enhanced the antioxidizing property and water repellency of the perovskite layer owing to the elimination of superoxide anion radical and hydrophobic molecular structure and improved the durability of the cells.
In the present work, an efficient route has been further explored to achieve the batch synthesis of inorganic fullerene (IF)-WS2 nanoparticles, and the self-lubricating film is conveniently prepared by coating these nanoparticles on the surface of metal substrates. The as-synthesized IF-WS2 nanoparticles have a closed hollow structure with an average particle size of about 50 nm and are evenly distributed in the self-lubricating film. Further friction tests show that the film has excellent friction properties, with its lowest friction coefficient of approximately 0.008, which can be mainly attributed to the unique hollow cage structure and a smaller particle size of the IF-WS2 nanoparticles.
This work demonstrated the possibility to integrate electrochemical molecularly imprinted polymers (e-MIPs) on microelectrodes to detect organic pollutants. e-MIPs are a cross-linked polymer with specific target binding cavities with a redox tracer inside. e-MIPs were obtained by precipitation copolymerization of ferrocenylmethyl methacrylate as a functional monomer and a redox tracer with ethylene glycol dimethacrylate as a cross-linker and bisphenol A as a target molecule. FTIR and elemental analysis confirmed the presence of ferrocene inside the polymers. Nitrogen adsorption/desorption experiments and binding isotherms demonstrated the presence of binding cavities inside the e-MIP. The electrochemical properties of the e-MIP were characterized in organic/aqueous media before their patterned on microelectrode.
The lifetime of cyclically loaded devices is often limited by the fatigue resistance of their individual phases. An advanced method is presented for measuring the high-cycle fatigue behavior of materials at the micrometer scale using a nanoindenter. It is based on the cyclic deflection of focused ion beam-fabricated microcantilevers using the continuous stiffness method (CSM). In line with experimental data on bulk nanocrystalline copper, the specimens exhibit grain coarsening followed by the formation of extrusions and a fatigue strength exponent of −0.10. The method is suitable for characterizing single phases and individual components of further complex systems.
β-Alanine and its derivatives are important starting materials for the preparation of peptides or compounds with biological activity. In this work, the authors are presenting a new approach for the synthesis of N-alkyl-β-amino acids and N-alkyl-β-amino esters using dendrimeric intermediates in a one-pot reaction, with friendly reaction conditions. Dendrimeric compounds, with a pentaerythritol core, were easy prepared and used to obtain the β-amino acid derivatives and β-amino esters with good yields. This paper presents the first reaction where dendrimers are used for synthesizing organic compounds. Spectroscopic characterization by 1H- and 13C-NMR of dendrimers and final products is also presented.
Stable superhydrophobic coatings were produced from aqueous suspensions of epoxy nanoparticles. The superhydrophobic coatings demonstrated excellent mechanical robustness and chemical resistance. Aqueous solutions of ionic surfactants, nonionic surfactants, and small organic molecules on superhydrophobic coatings could wet the superhydrophobic coatings. However, the superhydrophobicity can be recovered by rinsing the wet surface with water. It was also discovered that, although seemed wetted, the superhydrophobic surface was separated from the solution of ionic surfactant by a layer of ionic surfactant molecules. In contrast, nonionic and small organic molecules could not aggregate on the superhydrophobic surfaces; the coatings were exposed to the solutions.
In this work, the authors developed SiC(10 nm)/Ag/SiC(10 nm) thin films showing an electroforming-free resistive switching (RS) effect with a switching ratio of 102. The observed RS effect is attributed to charging and discharging of Ag nanoparticles in the film layer. Further, SiC/Ag/SiC film shows an excellent endurance and retention as well as a good thermal stability of RS characteristics. It is also identified that the switching ratio is invariant but the switching voltage of the device greatly depends on the Ag nanoparticles concentration and the operation temperature of the device. Therefore, SiC/Ag/SiC thin films are attractive for next-generation memory devices with enhanced durability.