Structure and properties of highly stereoregular isotactic poly(methyl methacrylate) and syndiotactic poly(methyl methacrylate) blends treated with supercritical CO2

The structure and properties of highly stereoregular isotactic poly(methyl methacrylate) (it-PMMA) and syndiotactic poly(methyl methacrylate) (st-PMMA) blends with crystalline stereocomplex formed by supercritical CO₂ treatment at temperatures ranging from 35 to 130 °C were investigated by means of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and dynamic mechanical analysis (DMA) measurements. The melting temperature, T_m, and the heat of fusion, ΔH_m, had maximum values at about 200 °C and 25 J/g, respectively. The degree of crystallinity evaluated by WAXD ranged in value from 32 to 38%. The fringed-micellar stereocomplex crystallites were formed in case of treatment temperatures below 90 °C, and the orderliness perpendicular to the helix axis of the fringed-micellar crystallites was considered to be increased with increasing treatment temperature. In case of treatment temperature of 130 °C, the fringed-micellar crystallites and the lamellar crystallites with high orderliness parallel to the helix axis coupled with the perpendicular orderliness were formed, and the respective double endothermic peaks, T_m¹ and T_m³, were observed in DSC due to the melting of the two kinds of stereocomplex crystallites. The it-PMMA/st-PMMA blends containing the fringed-micellar crystallites maintained high values of storage modulus, E′, up to higher temperature compared with the amorphous blends. The E′ of the blend treated with CO₂ at 130 °C decreased twice at temperatures corresponding to T_m¹ and T_m³.     

Preparation and thermal properties of semi-rigid rod-like homo- and copoly(ester-imide)s containing diphenyl ether dicarboximide units

Novel semi-rigid rod-like homo- and copoly(ester-imide)s, composed of 3,4,3′,4′-diphenyl ether dicarboximide rings having no N-phenyl groups next to the imide ring, were synthesized by transesterification of a dihexanol derivative of 3,4,3′,4′-diphenyl ether dicarboximide and/or a dioxydihexanol of biphenyl with aliphatic dimethyl esters. The thermal and mesogenic properties of these polymers were evaluated. The expected structures of the polymers were confirmed by FTIR, ¹³C-NMR spectroscopy and elemental analyses. From DSC measurements, optical texture observations by means of a polarizing microscope equipped with a hot stage, and temperature-dependent X-ray analyses, it was determined that the biphenyl-unit-rich polymers form nematic phases, but the diphenyl ether dicarboximide containing homopolymers have no liquid crystalline phases in the melt. It was suggested that the mesogenic character of the 3,4,3′,4′-diphenyl ether dicarboximide ring is low. TG-DTA measurements showed that the polymers are thermally stable up to 300°C in air.     

A statistical modeling methodology for the analysis of term structure of credit risk and its dependency

This paper presents a statistical modeling methodology for simultaneous estimation of the term structure for the risk-free interest rate, hazard rate, loss given default as well as credit risk dependency structure between bond-issuing industries. A model like this provides a realistic view for the market anticipation of credit risk for corporate bonds and the flexibility in capturing credit risk dependency between industries. Our statistical modeling procedure is carried out without specifying the model likelihood explicitly, and thus robust to the model mis-specification. An empirical analysis is conducted using the financial information on the Japanese bond market data. Numerical results confirm the practicality of the proposed methodology.     

Construction and development of a time-resolved x-ray magnetic circular dichroism-photoelectron emission microscopy system using femtosecond laser pulses at BL25SU SPring-8

A femtosecond pulsed laser system has been installed at the BL25SU soft x-ray beamline at SPring-8 for time-resolved pump-probe experiments with synchronization of the laser pulses to the circularly polarized x-ray pulses. There are four different apparatuses situated at the beamline; for photoemission spectroscopy, two-dimensional display photoelectron diffraction, x-ray magnetic circular dichroism (XMCD) with electromagnetic coils, and photoelectron emission microscopy (PEEM). All four can be used for time-resolved experiments, and preliminary investigations have been carried out using the PEEM apparatus to observe magnetization dynamics in combination with XMCD. In this article, we describe the details of the stroboscopic pump-probe XMCD-PEEM experiment, and present preliminary data. The repetition rate of the laser pulses is set using a pulse selector to match the single bunches of SPring-8's hybrid filling pattern, which consists of several single bunches and a continuous bunch train. Electrons ejected during the bunch train, which do not provide time-resolved signal, are eliminated by periodically reducing the channel plate voltage using a custom-built power supply. The pulsed laser is used to create 300 ps long magnetic field pulses, which cause magnetic excitations in micron-sized magnetic elements which contain magnetic vortex structures. The observed frequency of the motion is consistent with previously reported observations and simulations.     

Automated identification of partially exposed metal object

This paper describes a method for automated shape and pose (position and orientation) identification of partially exposed metal objects that enables safe and efficient excavation of hazardous materials. The method estimates the object pose by matching a model of the object with the area that is extracted from the range image using the characteristics of metal objects. The paper introduces a method for an initial search area for object matching in order to obtain the accurate shape and pose of the partially exposed objects with reasonable calculation time. The experimental results show feasibility of the shape and pose identification of partially exposed objects.     

Development of a Novel Anti−CD44 Monoclonal Antibody for Multiple Applications against Esophageal Squamous Cell Carcinomas

CD44 is a cell surface glycoprotein, which is expressed on normal cells, and overexpressed on cancer cells. CD44 is involved in cell adhesion, migration, proliferation, survival, stemness, and chemo−resistance. Therefore, CD44 is thought to be a promising target for cancer diagnosis and therapy. In this study, we established anti−CD44 monoclonal antibodies (mAbs) by immunizing mice with a CD44 variant (CD44v3−10) ectodomain and screening using enzyme−linked immunosorbent assay. We then characterized them using flow cytometry, Western blotting, and immunohistochemistry. One of the established clones (C₄₄Mab−46; IgG₁, kappa) reacted with CD44 standard isoform (CD44s)−overexpressed Chinese hamster ovary−K1 cells (CHO/CD44s) or esophageal squamous cell carcinoma (ESCC) cell lines (KYSE70 and KYSE770). The apparent K_D of C₄₄Mab−46 for CHO/CD44s, KYSE70, and KYSE770 was 1.1 × 10⁻⁸ M, 4.9 × 10⁻⁸ M, and 4.1 × 10⁻⁸ M, respectively. C₄₄Mab−46 detected CD44s of CHO/CD44s and KYSE70, and CD44 variants of KYSE770 in Western blot analysis. Furthermore, C₄₄Mab−46 strongly stained the formalin−fixed paraffin−embedded ESCC tissues in immunohistochemistry. Collectively, C₄₄Mab−46 is very useful for detecting CD44 in various applications.     

An efficient execution of Monte Carlo simulation based on delta-tracking method using GPUs

An efficient execution method for Monte Carlo simulation using graphic processing unit (GPU) is proposed. The delta-tracking method is used since the delta-tracking method can reduce conditional branches and complexity of code implementation, which degrade computational performance on GPUs. In order to improve parallel efficiency in the eigenvalue calculation, generated fission neutrons are recorded using the atomic operation which avoids the data race in GPUs. We also propose a method to efficiently tally neutron flux in a region. The present method is based on the atomic operation and use of fixed-point type number instead of common floating-point type number. The verification calculations using the C5G7 benchmark problem show effectiveness of the proposed numerical algorithms on GPUs through comparison with calculations using central processing units.     

Hydroxyapatite formation on porous ceramics of alpha-tricalcium phosphate in a simulated body fluid

Alpha-tricalcium phosphate (α-TCP) ceramic is a bioresorbable material that degrades in bone tissue after implantation, since it exhibits higher solubility than beta-tricalcium phosphate (β-TCP) ceramics. The high solubility of α-TCP in an aqueous solution causes its transformation into hydroxyapatite (HAp) through hydrolysis. While one expects the formation of hydroxyapatite after exposure to an aqueous solution mimicking a body environment, we occasionally find variation in HAp formation in the simulated body fluid (SBF). In the present study, HAp formation resulting from exposure to SBF was investigated for some types of α-TCP ceramics with different porosities and specific surface area. Reduced porosity and large surface area of porous specimens may increase the local density of Ca²⁺ in the surrounding SBF to increase the degree of supersaturation with respect to HAp. Thus, the porosity and specific surface area are significant parameters for determining not only bioabsorbability but also the ability to form HAp.     

Transmission analysis of electromagnetic induction RFID system

The transmission characteristics of the electromagnetic induction RFID systems are greatly influenced by the distance between the primary and secondary antenna coils and by the materials used in their design. In this paper the induced current of the secondary antenna coil is calculated by the 3D finite element method when both the primary and secondary antenna coils are operated in resonant circuits. The influences of the analyzed parameters on the transmission characteristics are demonstrated. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(4): 38–45, 2010; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21019     

Production and bond strength of similar-titanium ultrasonic welded joints

The joinability of unalloyed titanium and the bond strength of similar titanium welded joints by ultrasonic welding were investigated. It turned out that sound welded joints of similar titanium were obtained by using the jig for fixing both base metals. In the case of non-fixing and fixing the lower base metal, sound welded joints were not usually obtained due to the slip between the two base metals. Producing welded joints having sufficient bond strength required a certain threshold value of the ultrasonic energy. When the ultrasonic welding was carried out under the condition where the ultrasonic energy was higher than a threshold value (approximately 2000 W s), the welded joints were fractured within the titanium base metal but not at the interface. The values of the bond strength were associated with the fixing method and the surface roughness of the base metals. The bond interface was joined metallurgically for the most part, although some small voids were observed on the bond interface by SEM and EPMA observation.