Atomic and electronic structures of Li4Ti5O12/Li7Ti5O12 (001) interfaces by first-principles calculations

We have performed density-functional theory calculations for Li₄Ti₅O₁₂/Li₇Ti₅O₁₂ (LTO/Li-LTO) interfaces and made a detailed analysis of the local atomic and electronic structures. In the bulk regions of the supercell, the atomic and electronic structures are well reproduced to be similar to those of the LTO and Li-LTO bulk crystals. The present (001) interface models show abrupt structural changes between the cubic spinel-based LTO and ordered rock-salt Li-LTO phases, while there occur no substantial strains around the interface due to the little volume change or lattice mismatch. Thus, the calculated interfacial energy is very small. The calculated O–K electron energy-loss near-edge structure/X-ray adsorption near-edge structure (ELNES/XANES) spectra in the bulk regions are similar to those of the bulk crystals, while the O–K edge spectra at the two kinds of interfaces have specific shapes, differently from the simple superposition of the bulk spectra. The preferential occurrence of the (001) interface can be understood from the preferential Li diffusion along the [110] direction in LTO and the small interfacial energy.     

An experimental study on frosting of laminar air flow on a cold surface with local cooling

This paper presents the heat and mass transfer characteristics of the humid airflow in frosting conditions. A flat plate of aluminum with cooling modules at the central region was used for the simulation of flat surface part of the fin of the heat exchanger. The local surface temperature of the plate and the local thickness and total mass of the frost on the plate were measured to analyze the heat and mass transfer characteristics. In order to analyze the frosting characteristics, an analysis algorithm was developed, which can provide the local air temperature, the frost surface temperature, the sensible and the latent heat flux distributions at the test plate. Also, by integrating the local heat flux distribution, the average heat flux characteristics were analyzed. The present experiment and analysis found that the characteristic of the upstream airflow was very different from that of the downstream airflow.     

TiO2 Nanoparticles with High Photocatalytic Activity Under Visible Light

TiO₂ nanoparticles (C-TNT) with high visible light activity were obtained by carbonization of titania nanotubes (TNT) in an ethanol atmosphere under elevated pressure at 180 and 220 °C. New material was characterised by means of UV–Vis/DR, FTIR/DRS, TEM, and XRD. The photocatalytic activity was tested during monoazo dye decomposition under artificial solar light irradiation. Modified photocatalyst (220 °C, 4 h) had higher photocatalytic activity than both the pristine and commercial P25 catalysts.     

Application and development of synthetic polymer membranes. II. Separation of aqueous ethanol solution through poly(tert-butyl methacrylate-co-styrene) membranes

Separation of aqueous ethanol solution was carried out by pervaporation using a membrane which consisted of common polymer membranes. A membrane obtained from poly(tert-butyl methacrylate-co-styrene) was effective for a selective separation of ethanol from aqueous ethanol solution by pervaporation technique. The pervaporation ethanol–water mixture through the present membranes was analyzed as a solution–diffusion process, on the assumption that the both diffusion coefficients of each component are an exponential function of ethanol concentration.     

Chemical composition of Athabasca bitumen

A detailed analysis has been carried out on the deasphaltened Athabasca bitumen using two different series of Chromatographic separations followed by i.r., u.v., n.m.r. and computerized GC/MS studies of the separated fractions: saturates (22–25%), monoaromatics (10.3–10.8%), diaromatics (4.6–5.3%), polyaromatics and non-specific polar compounds (28.6%), acids (16.5%), bases (7.8%), and neutral nitrogen compounds (1.6%). The acyclic paraffin content of the maltene is low: straight-chain paraffins and the isoprenoids, phytane and pristane, are present in very low concentrations. Polycyclic saturates represent about 90% of the saturate fraction. The presence of C-27 and C-29–C-35 hopanes of the 17(h):21β(H) series and C-21–C-30 steranes was established. The mono- and diaromatic fractions were analysed by computerized mass spectrometry. The monoaromatic fraction contains alkylbenzenes, naphthenebenzenes and dinaphthenebenzenes in a ratio of 1.0:1.7:1.3. The ratio for naphthalenes, acenaphthenes + dibenzofurans and fluorenes in the diaromatic fraction is 1:0.9:0.5.     

In situ ESR measurement of mesophase formation during the heat treatment and cooling processes of pitches

Both heating and cooling processes for mesophase formation from various pitches have been followed by in situ ESR measurements. In addition to signal intensity and linewidth, the saturation phenomenon of the signal intensity with changing microwave power was measured during heat treatment and cooling processes. As a convenient measure of the saturation factor, l/P_max(P_max is the microwave power at which the signal shows maximum intensity) was employed. In general, 1/P_max decreased with an increase in heat-treatment temperature; this change seems to correspond to a decrease in the viscosity of pitch. When pitches were heat treated at 500°C for 2 h, the carbonization reactions and the rearrangement of molecules may occur, which irreversibly changes 1/P_max. Pronounced differences in the behavior of 1/P_max measured during cooling of the heat-treated pitches were found to depend upon pitch optical texture (isotropic, flow and mosaic).     

Fracture behavior of wasted activated carbon powder composites

At the Waterworks Bureau (Tokyo Metropolitan Government), activated carbon has been used for filtering water. After being used for the filtering process, it is normally disposed or burned for thermal recycling. However, CO₂ emissions occur during the thermal recycling. This work focuses on the identification of mechanical behavior of recycled wasted activated carbon (WAC) in order to elaborate smart materials having mechanical–electrical functions. Acoustic emission technique (AE) was used intensively as characterization support in which sensors were attached to detect microdamage during bending tests. At first, the resonant frequencies of the specimens were measured using the through-transmission test. The resonant frequencies of the specimens containing low weight fractions of WAC powder were less in comparison to the frequencies of the specimens with higher volume fraction. The frequency analysis was carried out with the projected wavelet transform on the signals detected during bending tests. Obtained data showed that, typically, the first major peaks showed the resonant frequency of the sensors, while the second major peaks exhibited signals indicative of resin cracking. The surfaces of the fractured specimens were analyzed by optical microscopy in order to visualize the crack formation and propagation on the activated carbon composite under flexural stresses. Consequently, fractographic and AE analyses provide better understanding of the failure mechanisms involved.     

Highly Mobile Metastable State of He-4 Thin Films: A Glass Transition by Mechanical Perturbation?

Solid layers of helium on graphite surface are known to go into a highly mobile state (HMS) once the solid layer is enforced to slip on the substrate. The HMS collapses to the stable inert state with the lifetime extending over \(10^4\) s. In this paper, we suggest that the HMS is a structural glass by showing the similarities between the present system and an organic conductor named BEDT-TTF. The latter was recently discovered to be an electronic glass if the cooling rate is rapid enough across the freezing temperature (Wigner crystal formation temperature). We then address a novel annealing process promoted by a local condensate which should be seen for the present He-4 case as the condensation fraction grows in the liquid overlayer.     

Reversible selectivity of water/organic solvent mixtures in poly(lactic acid) film

The separation properties of water/organic solvent mixtures in poly(lactic acid) (PLA) films were investigated. The organic solvent flux increased linearly as the feed concentration increased, whereas the water flux was almost constant up to a feed concentration of 30 wt %. Interestingly, the permselectivity of PLA films was reversed from organic solvent selectivity to high water selectivity depending on the type of organic solvent. The permselectivity was strongly correlated with the solution concentration at which the solvent‐induced crystallization of the PLA films occurred. The selectivity of permeation, solution, and diffusion in water/organic solvent mixtures was determined by the expanded free volume of the PLA films as a result of the interaction between PLA and the water/organic solvent mixture. The permeability behavior of water/organic solvent mixtures in PLA films was very complex. However, it was found that this behavior could be predicted through immersion tests. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43822.