Enhancing the thermal conductivity of polyacrylonitrile- and pitch-based carbon fibers by grafting carbon nanotubes on them

The thermal conductivities of ultrahigh tensile strength polyacrylonitrile (PAN)-based (T1000GB) and ultrahigh modulus pitch-based (K13D) carbon fibers with carbon nanotubes (CNTs) grown on them using chemical vapor deposition were measured using a thermal diffusivity meter. The thermal conductivities of the resulting hybrid materials were calculated to be 18.6 ± 1.7 and 965.6 ± 30.0 W/m K for T1000GB and K13D, respectively, while the respective original conductivities were 12.6 ± 1.0 and 745.5 ± 16.0 W/m K. The results clearly show that the CNTs grafting improves the thermal conductivities of both types of fiber.     

Comparative study of Nd:YAG laser-induced breakdown spectroscopy and transversely excited atmospheric CO2 laser-induced gas plasma spectroscopy on chromated copper arsenate preservative-treated wood

Taking advantage of the specific characteristics of a transversely excited atmospheric (TEA) CO(2) laser, a sophisticated technique for the analysis of chromated copper arsenate (CCA) in wood samples has been developed. In this study, a CCA-treated wood sample with a dimension of 20 mm × 20 mm and a thickness of 2 mm was attached in contact to a nickel plate (20 mm × 20 mm × 0.15 mm), which functions as a subtarget. When the TEA CO(2) laser was successively irradiated onto the wood surface, a hole with a diameter of approximately 2.5 mm was produced inside the sample and the laser beam was directly impinged onto the metal subtarget. Strong and stable gas plasma with a very large diameter of approximately 10 mm was induced once the laser beam had directly struck the metal subtarget. This gas plasma then interacted with the fine particles of the sample inside the hole and finally the particles were effectively dissociated and excited in the gas plasma region. By using this technique, high precision and sensitive analysis of CCA-treated wood sample was realized. A linear calibration curve of Cr was successfully made using the CCA-treated wood sample. The detection limits of Cr, Cu, and As were estimated to be approximately 1, 2, and 15 mg/kg, respectively. In the case of standard LIBS using the Nd:YAG laser, the analytical intensities fluctuate and the detection limit was much lower at approximately one-tenth that of TEA CO(2) laser.     

Tensile properties of high strength polyacrylonitrile (PAN)-based and high modulus pitch-based hybrid carbon fibers-reinforced epoxy matrix composite

The tensile properties of high strength polyacrylonitrile-based (IM600) and high modulus pitch-based (K13D) hybrid carbon fibers-reinforced epoxy matrix composite (CFRP) were investigated. Fiber orientation of the hybrid CFRP specimen was set to [0_(IM600)/0_(K13D)]_2S. The fiber volume fraction of the hybrid CFRP specimen was 55.7 vol% (IM600: 29.3 vol%, K13D: 26.4 vol%). The tensile stress–strain curve of the hybrid CFRP specimen shows a complicated shape (jagged trace). By the high modulus K13D CFRP layers, the hybrid CFRP specimen shows the intermediate modulus in the initial stage of loading. Subsequently, when the K13D CFRP layers begin to fail, the high strength IM600 CFRP layers would hold the load (strength) and the material continues to endure high load without instantaneous failure. Because higher strength fiber can help the load for a certain time after failure occur, the hybrid composite could be considered one example of a material possessing preventing instantaneous failure. The Weibull statistical distributions of the mono (IM600 and K13D) and the hybrid CFRP specimens were also examined. The Weibull modulus for the mono CFRP specimens was calculated to be 22.9 for the IM600 CFRP specimen and 14.4 for the K13D CFRP specimen, respectively. The Weibull modulus for the hybrid CFRP specimen was calculated to be 39.6 for the initial fracture strength and 20.6 for the tensile fracture strength, respectively. The Weibull modulus for the initial fracture strength is higher than that for the K13D CFRP specimen and the Weibull modulus for the tensile fracture strength is almost similar to that for the IM600 CFRP specimen.     

Development of a new noncontact gripper using swirl vanes

In this paper, we proposed a new noncontact gripper called as swirl gripper. It generates swirling air flow to create an upward lifting force. This force can be used to pick up a work piece placed underneath the swirl gripper without any contact. In comparison with conventional pneumatic noncontact grippers, the uniqueness of the new gripper lies in that it is electrically (rather than pneumatically) activated. We carry out this study for clarifying the mechanism of the swirl gripper. First, we show the design of the swirl gripper and briefly illustrate the mechanism by which it forms a negative pressure to create a lifting force. Then, we experimentally investigate the characteristics of the pressure distribution, based on which a theoretical analysis on the swirling flow is conducted. Furthermore, we measure the relationship between the lifting force and gap clearance and reveal that there exists a levitation zone where a work piece can maintain a stable levitation. Finally, we verify the practicability by successfully noncontact handling a Φ300 mm silicon wafer with four swirl grippers.     

Simulation of the EUV spectrum of Xe and Sn plasmas

Complex spectra of Xe and Sn, and their feasibility for use in the lithographic extreme ultraviolet (EUV) source, are investigated. By combining calculations of atomic data using the HULLAC code and the Whiam collisional radiative model with a simple radiative transfer model, the EUV spectrum is shown to originate from a large number of fine structure transitions. Satellite lines of 4d-4f and 4d-5p transitions from near ten times ionized states are found to make a significant contribution to the emission from an optically thick plasma. The wavelengths and transition probabilities of emission lines, charge state distribution, and level population in the plasma, as well as radiation intensity from a laser-produced plasma source have been calculated. The effect of opacity is taken into account assuming a local thermodynamic equilibrium population in the plasma. The calculated result reproduces the observed spectra both for Xe and Sn, showing applicability of the present method to the spectroscopy of hot dense plasmas.     

Identification of anti-α-enolase autoantibody as a novel serum marker for endometriosis

Diagnosis of endometriosis needs invasive maneuvers. New serum marker that possesses both high sensitivity and high specificity has long been desired. To establish novel serum marker for endometriosis, serum autoantibodies (autoAbs) were investigated using proteomic approach. AutoAbs in sera of endometriotic patients and healthy controls were analyzed using a mesothelial cell line, 2-DE and Western blotting. Proteins in reacted spots were identified using MALDI TOF-MS with MASCOT analysis. ELISAs were established using recombinant proteins and autoAb-titers were estimated in sera of endometriotic patients, disease and healthy controls. Several autoAbs were identified. Anti-α-enolase (Eno1)-autoAb levels in endometriotic patients were significantly elevated compared with both healthy and disease controls. Sensitivity and specificity of serum anti-Eno1-autoAb was nearly comparable to serum CA125. When anti-Eno1-autoAb and CA125 assays were combined, diagnostic sensitivity and accuracy improved. Serum anti-Eno1-autoAb can be a new serum endometriotic marker and it is useful as a supplement assay for CA125. This study validates further clinical evaluation of this novel marker.     

Creep and Fatigue Behavior in an Enhanced SiC/SiC Composite at High Temperature

The monotonic tension, creep, and fatigue behavior of an enhanced SiC/SiC composite was investigated at a temperature of 1300°C in air and argon. The improved creep and fatigue resistances were determined and compared to those of the standard SiC/SiC composite. The effects of additives (glass-forming, boron-based particulates) in the matrix on the creep and environmental resistance of the enhanced SiC/SiC composite were discussed. Crack propagation in the matrix of the enhanced SiC/SiC composite was different from that in the standard SiC/SiC composite. The filling of the glassy phases in the cracks prohibited the diffusion of oxygen from the environment. As a result, creep and fatigue properties in the enhanced SiC/SiC composite in air at high temperatures was improved.     

Factors affecting stretching limits of Aluminum sheet

The purpose of the present paper is to study methods to improve the stretching limit of metal sheet. The factors affecting the stretching limit were sheet thickness, blank diameter, blank holding pressure, and forming rate. Punch radius, die radius, and clearance between a punch and a die were retained constant. Tested materials were softened and half hardened types of aluminum sheet. The effect of lubrication was also studied. Lubricants used were a press working oil and graphite. Stretching by two types of punch shape, a spherical head punch and a truncated cone one, was tried in order to research the effect of punch shape. The half hardened aluminium, which has a larger n-value, showed the larger stretching limit. The larger thickness gave rise to the larger stretching limit. Flow characteristic of materials was poorer in larger diameter of a blank, so its stretching limit was lower. A bit lower holding pressure, which allows drawing of materials to some extent, yielded larger stretching limit than rigid holding. The forming rate did not so much affect stretching limit. Concerning the effect of lubrication, applied position of lubricants was important.     

Content of mutant mitochondrial DNA and organ dysfunction in a patient with a MELAS subgroup of mitochondrial encephalomyopathies

A point mutation of mitochondrial tRNALeu(UUR) gene is responsible for a MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) subgroup of mitochondrial encephalomyopathies. In most cases, the mutant mitochondrial DNA (mtDNA) coexists with normal mtDNA in a heteroplasmic manner. In order to quantify the content of mutant mtDNA, we developed a quantitative method of PCR. Using this method, the distribution of the mutant mtDNA was examined in 32 different tissues among 18 autopsied organs from a patient with MELAS, who had shown hypophyseal dysfunction. The percentage of the mutant mtDNA at nucleotide number 3243 in each tissue was ranged between 22% and 95%. The content of the mutant mtDNA was at the highest (95%) in the hypophysis and higher in the cerebral cortex than in the white matter. This study shows a possible correlation of tissue dysfunction with accumulation of the mutant mtDNA within the brain.     

Back-illuminated pulse-frequency-modulated photosensor using silicon-on-sapphire technology developed for use as epi-retinal prosthesis device

An intra-ocular epi-retinal prosthesis device using a back-illuminated photosensor is proposed and demonstrated for the first time. The photosensor, based on a pulse frequency modulation, is fabricated on a transparent sapphire substrate to detect the backside incident light. Experimental results show that the device is sensitive over a dynamic range of incident light of 30 dB.