Investigation of CH4 Reforming with CO2 on Meso-Porous Al2O3-Supported Ni Catalyst

Meso-porous Al₂O₃-supported Ni catalysts exhibited the highest activity, stability and excellent coke-resistance ability for CH₄ reforming with CO₂ among several oxide-supported Ni catalysts (meso-porous Al₂O₃ (Yas1-2, Yas3-8), -Al₂O₃, -Al₂O₃, SiO₂, MgO, La₂O₃, CeO₂ and ZrO₂). The properties of deposited carbons depended on the properties of the supports, and on the meso-porous Al₂O₃-supported Ni catalyst, only the intermediate carbon of the reforming reaction formed. XRD and H₂-TPR analysis found that mainly spinel NiAl₂O₄ formed in meso-porous Al₂O₃ and -Al₂O₃-supported catalysts, while only NiO was detected in -Al₂O₃, SiO₂, CeO₂, La₂O₃ and ZrO₂ supports. The strong interaction between Ni and meso-porous Al₂O₃ improved the dispersion of Ni, retarded its sintering and improved the activated adsorption of CO₂. The coking reaction via CH₄ temperature-programed decomposition indicated that meso-porous Al₂O₃-supported Ni catalysts were less active for carbon formation by CH₄ decomposition than Ni/-Al₂O₃ and Ni/-Al₂O₃.     

Spatial distribution of silica fillers in phase-separated rubber blends investigated by three-dimensional elemental mapping

The distribution of nano-sized silica in binary rubber blends is characterized by scanning transmission electron microscopy (STEM) tomography combined with energy dispersive X-ray spectrometry (EDX). 3D distribution of silica is visualized by STEM-EDX tomography with the tilt-series of silicon elemental maps, while the phase-separated morphologies of polyisoprene rubber (IR) and styrene-butadiene rubber (SBR) are visualized by STEM-tomography in high-angle-annular-dark field (HAADF) mode. The combination of STEM-EDX and STEM-HAADF tomography enables us to determine the distribution of silica between the two rubber phases quantitatively even with high contents of silica up to 70 phr (weight parts per hundred rubber). It is found that silica is preferentially distributed in the SBR phase, but it is also distributed in the IR phase when the IR fraction in the total rubber components is higher than 40 wt%. The preferential distribution of silica in the SBR phase improves the dispersion of the IR domains. This is the first use of this technique for a multicomponent polymer system, showing the advantage to characterize the complicated multicomponent polymer composite morphologies.     

Crack initiation model for sensitized 304 stainless steel in high temperature water

To investigate the initiation behavior of stress corrosion cracking (SCC) for sensitized Type 304 stainless steel in high temperature water, a constant load SCC test method combined with in situ crack observation technique was employed. The in situ crack observation system allowed us to detect small cracks of at least 100 μm. As a result, a fracture time decreased with an increase in an applied stress. The first cracks were observed at most 3 h before the specimen was fractured under all the stress conditions. After that, many cracks were initiated in a short time to fracture. The fracture was caused by coalescence of multiple cracks rather than by growth of some primary cracks. The simulation model for surface crack initiation was newly developed using a Monte Carlo method, which was based on damage mechanics and stress analysis around the existing cracks. The simulation could represent the empirical results of changes in the crack distribution and the cumulative number of cracks during the SCC tests. It was concluded, therefore, that the crack initiation process should be considered in simulating the life prediction of the material in this SCC system.     

Temperature-controlled molecular dynamics study on velocity-dependent threshold behavior of dynamic nano-friction

Laws of dynamic nano-friction (i.e., continuous wearless friction) were searched for under steady spatial distributions of the local quasi-temperature, by molecular dynamics (MD) simulations. The temperature control of the non-conservative model was carried out by extending the isothermal MD method using the Nosé–Poincaré thermostat. The results suggested that the threshold phenomenon characterizes sliding-velocity dependence of the nano-frictional force between crystal lattices constituting a nano-electromechanical system (NEMS). This phenomenon was turned out to be a universal feature, whether heat transfer to the environment exists or not.     

Gradually intractable problems and nondeterministic log-space lower bounds

The paper places five different problems (thek-pebble game problem, two problems aboutk finite automata, the reachability problem for Petri nets withk tokens, and the teachability problem for graphs whose k-dimensional edge sets are described by Cartesian products ofk factors) into the hierarchyNL _k of problems solvable by nondeterministic Turing machines ink-log₂ n space (and binary tape alphabet, to avoid tape speed-up). The results, when combined with the conjecture thatNL _i contains problems that requireO(n ^k ) deterministic time, show that these problems, while inP for every fixed value ofk, have polynomial deterministic time complexities with the degree of the polynomial growing linearly with the parameterk, and hence are, in this sense, gradually intractable.     

LaBGeO5 single crystals in glass and second-harmonic generation

Flower-shaped crystals with diameters of 100–200 μm consisting of LaBGeO₅ (LBGO) single crystals similar to petals were observed in the interior of transparent LBGO surface-crystallized glasses. Each flower-shaped crystal was radially grown from the surface of the included bubbles. A more intense second-harmonic generation was observed from the LBGO crystallized glasses with the flower-shaped LBGO single crystals compared to the samples without such crystals based on the Maker fringe technique and second-harmonic (SH) generation microscopy. The SH intensity for the flower-shaped LBGO single crystals monotonically decreased with increasing temperature up to 350 °C, less than the Curie temperature reported so far (530 °C). It is considered that the internal compressive stress induced by the difference in the thermal expansion between the LBGO single crystal and the corresponding glass affect the ferroelectric property of the flower-shaped LBGO single crystals in glass.     

The Atmospheric Scanning Electron Microscope with open sample space observes dynamic phenomena in liquid or gas

Although conventional electron microscopy (EM) requires samples to be in vacuum, most chemical and physical reactions occur in liquid or gas. The Atmospheric Scanning Electron Microscope (ASEM) can observe dynamic phenomena in liquid or gas under atmospheric pressure in real time. An electron-permeable window made of pressure-resistant 100 nm-thick silicon nitride (SiN) film, set into the bottom of the open ASEM sample dish, allows an electron beam to be projected from underneath the sample. A detector positioned below captures backscattered electrons. Using the ASEM, we observed the radiation-induced self-organization process of particles, as well as phenomena accompanying volume change, including evaporation-induced crystallization. Using the electrochemical ASEM dish, we observed tree-like electrochemical depositions on the cathode. In silver nitrate solution, we observed silver depositions near the cathode forming incidental internal voids. The heated ASEM dish allowed observation of patterns of contrast in melting and solidifying solder. Finally, to demonstrate its applicability for monitoring and control of industrial processes, silver paste and solder paste were examined at high throughput. High resolution, imaging speed, flexibility, adaptability, and ease of use facilitate the observation of previously difficult-to-image phenomena, and make the ASEM applicable to various fields.     

Improvement of lysozyme recovery method from the precipitate of protein-anionic surfactant complexes

A new protein separation process using a surfactant and a polar organic solvent consists of a precipitation step and a recovery step. In the precipitation step, a protein-surfactant complex is precipitated from an aqueous solution, when an ionic surfactant, sodium di(2-ethylhexyl) sulfosuccinate (AOT), is added to an aqueous solution, including protein (lysozyme). In the recovery step, the precipitate is dissolved in a polar organic solvent, such as acetone, and the protein is recovered as precipitates when a very small amount of salt solution was added to remove surfactants from the protein-surfactant complex. However, the details of the protein recovery step from precipitate have not been studied yet. In this study, the improvement of the protein recovery step was examined from the viewpoint of a recovery ratio of protein and a remaining ratio of surfactant. The optimum NaCl concentration in the feed for the protein recovery was in the range of 0.05–0.2 kmol/m³. As the NaCl concentration in the feed increased to more than 0.2 kmol/m³, the precipitation ratio decreased due to the electrostatic screening effect of NaCl. It was found that the addition of a very small amount of NaCl solution to acetone was unnecessary when NaCl was included in the feed lysozyme solution. On the other hand, as the NaCl concentration decreased to less than 0.05 kmol/m³, the precipitation ratio was decreased due to the low re-precipitation of protein by the addition of a small amount of NaCl solution in acetone. In the case of the feed containing no salt, the desired NaCl concentration added to acetone was in the range above 0.2 kmol/m³. In addition, the most suitable volume ratio of acetone to feed was found to be 0.2.     

Accelerated Discovery of Potent Bioactive anti-TNFα Aptamers by Microbead-Assisted Capillary Electrophoresis (MACE)-SELEX

Dysregulation of tumor necrosis factor-α (TNFα), a pro-inflammatory cytokine, causes several diseases, making it an important therapeutic target. Here, we identified a novel DNA aptamer against human TNFα using in vitro selection, which included a high exclusion pressure process against non-binding and weak binders through microbead-assisted capillary electrophoresis (MACE) in only three rounds. Among the 15 most enriched aptamers, Apt14 exhibited the highest inhibitory activity for the interaction between TNFα and its cognate receptor in mouse L929 cells. For further improving the bioactivity of the aptamer, dimerization programed by hybridization was evaluated, resulting in the Apt14 dimer exhibited a twofold higher binding affinity and stronger inhibition compared to the monomer counterpart. Rapid identification of bioactive aptamers using MACE in combination with facile dimerization by hybridization accelerates the discovery of novel bioactive aptamers, paving the way toward replacing current monoclonal antibody therapy with the less expensive and non-immunogenic aptamer therapy.