Mixtures of elementary oxides, MgO–Al2O3, were used to fabricate transparent polycrystalline magnesium aluminate spinel specimens by means of the spark plasma sintering technique. A sintering aid, 1 wt% of LiF, was added to the mixed powder. The presence of the additive promotes the synthesis of spinel that starts at 900°C and is completed at 1100°C. The LiF additive wets spinel on its melting and promotes densification, which is completed at 1600°C. LiF vapor plays a cardinal role in eliminating residual carbon contamination and in the fully dense state, allows attaining a 78% level of optical transmittance. The optimal conditions for achieving adequate transparency were determined and the role of the LiF addition in the various stages of the process is discussed.

Self-assembled nanocomplexes composed of individual molecules that spontaneously connect via noncovalent interactions have recently emerged as versatile alternatives to conventional controlled drug delivery systems because of their unique bioinspired properties (responsiveness, dynamics, etc.). Characterization of such nanocomplexes typically includes their size distribution, surface charge, morphology, drug entrapment efficiency, and verification of the coexistence of labeled components within the nanocomplexes using a colocalization study. Less common is the direct examination of the molecular interactions between the different components in the coassembled nanocomplex, especially in nanocomplexes composed of hygroscopic components, because convenient methods are still lacking. Here, we present a detailed experimental protocol for determining the surface composition and the chemical bonds by X-ray photoelectron spectroscopy (XPS) after drying the deposit hygroscopic sample overnight under UHV. We applied this method to investigate the surface chemistry of binary Ca 2+ -siRNA nanocomplexes and ternary nanocomplexes of hyaluronan-sulfate (HAS)-Ca 2+ -siRNA, deposited on a wafer. Notably, we showed that the protocol can be implemented to study the surface composition and interactions of the deposited nanocomplexes with a traditional XPS instrument, and it requires only a relatively small amount of the nanocomplex suspension.

Three materials containing Ni 2 P, Ni 12 P 5 , and Ni 3 P phases on silica gel with surface area 320 m 2 /g at loadings of 32-37 wt % and the crystal size of Ni x P phases 30, 9, and 13 nm, respectively, were prepared by a combination of impregnation and TPR methods and tested in hydrodesulfurization (HDS) and adsorptive desulfurization (ADS) of diesel fuel. There were established opposite trends in changing the DS efficiency in two processes: The HDS rate constant decreased while the ADS sulfur capacity (breakthrough at 1 ppmw) increased with increasing the Ni to P ratio in Ni x P from 2 to 3. The observed behavior was attributed to the specific features of the densities of states (DOS) obtained from the density functional theory calculations of total and partial DOS for Ni and P in Ni x P phases and revealed in XPS measurements of binding energy of Ni 2p 3/2 -and P 2p-electrons. This attribution was consistent with the analysis of the relative part of d-electrons of Ni participating in bonding with p-electrons of phosphorus in these phases.

We report on a combined investigation of the structure and chemical bonding in fluorinated detonation nanodiamond by means of nuclear magnetic resonance, electron paramagnetic resonance, X-ray photoelectron spectroscopy, and Raman measurements. The results of these methods are found to be consistent with each other and evidence formation of different fluorocarbon groups on the nanodiamond surface, which substitutes for hydrocarbon and hydroxyl groups. The data obtained provide detailed information about the structure and bonding in the fluorinated diamond nanoparticle. The fluorinated sample has a significant number of paramagnetic defects (∼10 20 spin/g) located mainly near the surface of the diamond nanoparticle, resulting in fast 19 F and 13 C nuclear spin-lattice relaxation.

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Construction of structurally defi ned, patterned metal fi lms is a fundamental objective in the emerging and active fi eld of bottom-up nanotechnology. A new strategy for constructing macroscopically organized Au nanostructured fi lms is presented. The approach is based upon a novel phenomenon in which incubation of water-soluble Au(SCN) 4 1 − complex with amine-displaying surfaces gives rise to spontaneous crystallization and concurrent reduction, resulting in the formation of patterned metallic gold fi lms. The Au fi lms exhibit unique nanoribbon morphology, likely corresponding to aurophilic interactions between the complex moieties anchored to the amine groups through electrostatic attraction. Critically, no external reducing agents are needed to initiate or promote formation of the metallic Au fi lms. In essence, the thiocyanate ligands provide the means for surface targeting of the complex, guide the Au crystallization process and, importantly, donate the reducing electrons. It is shown that the Au fi lms exhibit electrical conductivity and high transparency over a wide spectral range, lending the new approach to possible applications in optoelectronics, catalysis, and sensing. In a broader context, a new gold chemistry route is presented in which ligandenabled crystallization/reduction could open the way to a wealth of innovative reaction pathways and applications.

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The lower performance of pseudocapacitive supercapacitors in high‐frequency applications such as alternating current (AC) line filtering has been ascribed to presumed slow kinetics of redox processes compared to ion diffusion in electric double layer capacitors. A nickel‐deposited ruthenium/ruthenium‐oxide symmetric supercapacitor exhibiting remarkable electrochemical properties, particularly very high frequency response (>1 kHz) is developed. The electrodes are prepared via a simple process consisting of electrochemical reduction of ruthenium chloride on commercially available nickel foil as the current collector. A symmetric supercapacitor comprising nickel/ruthenium/ruthenium‐oxide electrodes and a polystyrene‐based thin spacer exhibits particularly fast scan rates, high power density of 1500 mW cm−2 (88 kW cm−3) with a maximum energy density of 0.58 µWh cm−2 (34 mWh cm−3), and excellent capacitance retention. Notably, supercapacitors prepared by the same synthetic method albeit using conventional gold substrate instead of nickel exhibit significantly lower frequency response. The exceptional electrochemical properties of the nickel/ruthenium/ruthenium‐oxide supercapacitor and simple electrode synthesis point to promising applicability in AC line filtering and power conditioning. In a broader context, this work demonstrates that, contrary to the widely held presumption, the kinetics of redox reactions at the active layers of pseudocapacitors may not be the primary barriers to high‐frequency applications.