Improvement of thickness uniformity and crystallinity of AlN films prepared by off-axis sputtering

We improved both the thickness uniformity and crystallinity of Aluminum nitride (AlN) films deposited by off-axis sputtering. The results in thickness uniformity and X-ray rocking curve full-width at half-maximum (FWHM) of AlN (0 0 0 2) are achieved to be ±0.2% and 1.4°, respectively on a 100 mm Si (1 0 0) substrate. The residual stress can be controlled from tensile to compressive by varying sputtering parameters such as gas pressure, RF power and DC bias voltage applied to a substrate without degradation in the crystallinity and thickness uniformity.     

An algorithm for detecting startle state based on physiological signals

To construct safe workspaces or daily life environments, it is important to develop a technology for automatically recording dangerous environmental situations. Based on increased finger skin conductance and decreased instantaneous heart (pulse) rate, we developed an algorithm for detecting the startle state of humans when encountering dangerous situations. The parameter values in the algorithm were optimized by tuning them with experimental results obtained in a virtual reality system, in which dangerous scenarios were presented to 21 subjects. The detection sensitivity of the optimized algorithm was 100% during a static standing condition and also while cycling. The detection specificity attained 90% and 87% for the static and exercising conditions, respectively. The optimized algorithm was applied to a real world situation such as car driving, and relatively high sensitivity of 87% and specificity of 80% were obtained.     

Molecular imprinting under molecular crowding conditions: an aid to the synthesis of a high-capacity polymeric sorbent for triazine herbicides

Molecular crowding, an important feature of the molecular environments in biological cells, was applied to the synthesis of antibody-mimic polymers selective for a group of biologically active compounds, the triazine herbicides. Synthesis of these polymers was conducted using molecular imprinting under molecular crowding conditions, whereby atrazine (a template molecule) was complexed with methacrylic acid (a functional monomer) in the presence of a macromolecular crowding agent (either poly(methyl methacrylate) (PMMA) or polystyrene (PS)) followed by cross-linking with ethylene glycol dimethacrylate. After removal of atrazine from the polymer matrix, the retention properties and selectivity of the resultant polymers were assessed by chromatographic tests. The addition of a crowding-inducing agent resulted in polymers with superior retention properties and excellent selectivity for triazine herbicides, as compared to polymers prepared without addition of a crowding-inducing agent. An imprinted polymer prepared in the presence of PS as a crowding agent exhibited a retention factor for atrazine an order of magnitude larger than that of an imprinted polymer prepared in the absence of a crowding agent. NMR results suggest that the crowding agent is capable of promoting hydrogen bond formation between atrazine and methacrylic acid, which could account for the effect of crowding on molecular imprinting.     

Postcolumn concentration in liquid chromatography. On-line eluent evaporation and analyte postconcentration in ion chromatography

On-line sample concentration by evaporation through a narrow-bore membrane tube is described. The device can be deployed just prior to the detector or the sample may be concentrated prior to injection. As solution flows through a solvent-permeable membrane tube, (heated) drying gas (nitrogen/air) flows outside it to remove the solvent. The removal rate increases with increasing sample residence time, drying gas flow rate, and temperature. Various membranes and three concentrator designs (a rectangular maze, a serpentine and a filament-filled helix, the last performing the best) were fabricated and tested for post- and preseparation applications in suppressed anion chromatography. An order of magnitude concentration factors are readily obtained. The present system involves active mass transport radially outward through the walls of a tube. This is a system in which many of the traditional paradigms of flow through a tubular conduit no longer hold true. Because the flow rate continuously varies along the tube, residence time does not scale linearly with residence volume or conduit length. The effects of such mass transport on the parabolic velocity profile of laminar flow remain unknown.     

Synthesis of one-dimensional sodium titanate nanostructures

We synthesized sodium titanate nanotubes and nanowires using TiB2 and TIN as the starting materials, respectively in a hydrothermal process. The experimental results indicate that the reaction temperature influences the morphology of the product significantly. The nanowires were formed above 170 degrees C. Nanotubes were obtained below 140 degrees C. The synthesized nanotubes exhibit a crystallized multi-wall structure. The inner diameter was found to be ca. 5 nm. The diameter of the nanowires was found to be ca. 50 nm. The characteristic lengths was in the order of tens micrometers.     

Effect of spatial variability of block-type cement-treated ground on the bearing capacity of foundation under inclined load

Deep mixing methods are widely used for stabilizing soft clayey soils and improving their bearing capacity. However, spatial variability in the shear strength of the cement-treated ground introduces uncertainties in estimating the bearing capacity for design. This paper evaluates the reliability of, block-type, cement-treated foundation under inclined load conditions using random field numerical limit analyses. The undrained shear strength is modelled as a random field which is characterized by a log-normal distribution and a spatial correlation length. Monte Carlo simulations are then used to interpret the stochastic bearing capacity factor and failure mechanisms for inclined concentric loading conditions at selected ratios of the shear strength ratio of cement-treated ground to original clay, the coefficient of variation in undrained shear strength and correlation length of the cement-treated zone. Variability of the undrained shear strength can reduce the expected bearing capacity of the cement-treated ground by 50–70% compared to homogeneously mixed clay.     

Controlling the Fluorescence of Benzofuran‐Modified Uracil Residues in Oligonucleotides by Triple‐Helix Formation

We developed fluorescent turn‐on probes containing a fluorescent nucleoside, 5‐(benzofuran‐2‐yl)deoxyuridine (dU^BF) or 5‐(3‐methylbenzofuran‐2‐yl)deoxyuridine (dU^MBF), for the detection of single‐stranded DNA or RNA by utilizing DNA triplex formation. Fluorescence measurements revealed that the probe containing dU^MBF achieved superior fluorescence enhancement than that containing dU^BF. NMR and fluorescence analyses indicated that the fluorescence intensity increased upon triplex formation partly as a consequence of a conformational change at the bond between the 3‐methylbenzofuran and uracil rings. In addition, it is suggested that the microenvironment around the 3‐methylbenzofuran ring contributed to the fluorescence enhancement. Further, we developed a method for detecting RNA by rolling circular amplification in combination with triplex‐induced fluorescence enhancement of the oligonucleotide probe containing dU^MBF.     

Rotational invariance of quaternionic hopfield neural networks

High‐dimensional neural networks have been studied by many researchers for their flexible representation. Quaternionic Hopfield neural networks (QHNNs) are one of them. Quaternions have the inherent property of non‐commutative multiplication. Connection weights act differently from left and right in QHNNs, and we can have left QHNNs (LQHNNs) and right QHNNs (RQHNNs). Hybrid QHNNs (HQHNNs), which are the compound models of LQHNNs and RQHNNs, have been proposed, and their excellent noise tolerance has been shown through computer simulations. It has been pointed out that the improvement in their noise tolerance is related to the avoidance of rotational invariance. Thus, it is very important to study rotational invariance. In this paper, we investigate the rotational invariance of QHNNs. Rotational invariance in LQHNNs and RQHNNs is different. We define the left and right‐rotated vectors, which are fixed in RQHNNs and LQHNNs, respectively. From the standpoint of HQHNNs, the common rotated vectors are important. We also study the common rotated vectors and provide a couple of exceptional examples. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Drying Behavior of a Slip Cast Body Using a Microwave Heating

To reduce the drying period a significant enhancement of manufacturing speed and improvement of productivity of ceramic fabrication were needed. The evaporation and transport of water were the keys to drying and controlling the kinetics of drying, which subsequently affects the properties of green bodies. This research was conducted to investigate the effects of rapid drying of ZnO slip cast bodies by microwave drying and compared with those dried by conventional drying techniques. From these results, the extent of warpage of a dried body was smaller in microwave drying than in other conventional drying methods. Furthermore, the number and size of pores were smaller for this drying technique than for other drying methods after sintering. Microwave heating was tentatively considered as a small difference in the water content between the inside and the outside of the green body, because the free and bound waters with NH₄⁺ salt of polyacrylic acid in a green body were selectively heated compared with ZnO powder, and evaporation and diffusion of water was done efficiently from the inside of the green body under microwave drying. Microwave drying has merits in terms of both the rapid drying and structural uniformity of dried bodies. It not only reduces drying period, but also improves the characteristics of green and sintered bodies.     

Comparison of mechanical properties of PP/SEBS blends at intermediate and high strain rates with SiO2 nanoparticles vs. CaCO3 fillers

The present article focuses on the effect of two types of inorganic fillers (SiO₂ and CaCO₃) on the mechanical properties of PP/SEBS blend. The nominal particle diameters of SiO₂ and CaCO₃ are 7 nm and 1 μm, respectively. The studied blend ratios were PP/SEBS/SiO₂ (CaCO₃) = 75/22/3 and 73/21/6 vol %. The morphology of polymer blends was observed and the distributions of the SEBS, SiO₂, and CaCO₃ particles were analyzed by transmission electron microscopy (TEM). Tensile tests were conducted at nominal strain rates from 3 × 10^?1 to 10² s^?1. The apparent elastic modulus has the local strain‐rate dependency caused by SiO₂ nanoparticles around SEBS particles in the blend of PP/SEBS/SiO₂. The yield stress has weak dependency of morphology. The absorbed strain energy has strong dependency of the location of SiO₂ nanoparticle or CaCO₃ fillers and SEBS particle in the morphology. It is considered that such morphology, in which inorganic nanoparticles are located around SEBS particles, can prevent the brittle fracture while the increased local strain rate can enhance the apparent elastic modulus of the blend at the high strain rate. On the basis of the results of this study, the location and size of inorganic nanoparticles are the most important parameters to increase the elastic modulus without decreasing the material ductility of the blend at both low and high strain rates. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008