High-precision CTE measurement of hybrid C/SiC composite for cryogenic space telescopes

This paper presents highly precise measurements of thermal expansion of a “hybrid” carbon-fiber reinforced silicon carbide composite, HB-Cesic® – a trademark of ECM, in the temperature region of ～310–10 K. Whilst C/SiC composites have been considered to be promising for the mirrors and other structures of space-borne cryogenic telescopes, the anisotropic thermal expansion has been a potential disadvantage of this material. HB-Cesic® is a newly developed composite using a mixture of different types of chopped, short carbon-fiber, in which one of the important aims of the development was to reduce the anisotropy. The measurements indicate that the anisotropy was much reduced down to 4% as a result of hybridization. The thermal expansion data obtained are presented as functions of temperature using eighth-order polynomials separately for the horizontal (XY-) and vertical (Z-) directions of the fabrication process. The average CTEs and their dispersion (1σ) in the range 293–10 K derived from the data for the XY- and Z-directions were 0.805 ± 0.003 × 10^?6 K^?1 and 0.837 ± 0.001 × 10^?6 K^?1, respectively. The absolute accuracy and the reproducibility of the present measurements are suggested to be better than 0.01 × 10^?6 K^?1 and 0.001 × 10^?6 K^?1, respectively. The residual anisotropy of the thermal expansion was consistent with our previous speculation regarding carbon-fiber, in which the residual anisotropy tended to lie mainly in the horizontal plane.     

Building a compact online MRF recognizer for large character set by structured dictionary representation and vector quantization technique

This paper describes a method for building a compact online Markov random field (MRF) recognizer for large handwritten Japanese character set using structured dictionary representation and vector quantization (VQ) technique. The method splits character patterns into radicals, whose models by MRF are shared by different character classes such that a character model is constructed from the constituent radical models. Many distinct radicals are shared by many character classes with the result that the storage space of model dictionary can be saved. Moreover, in order to further compress the parameters, VQ technique to cluster parameter sequences of the mean vectors and covariance matrixes for MRF unary features and binary features as well as the transition probabilities of each state into groups was employed. By sharing a common parameter sequence for each group, the dictionary of the MRF recognizer can be greatly compressed without recognition accuracy loss.     

Introduction of conductivity on non-conducting polyaniline by low-energy proton implantation

The semiconductor characteristics of a non-conducting polyaniline pellet can be modified by implantation of low-energy protons, that is, the resistivity became less than 50 Ω cm by proton doping at the fluence rate and fluence of 4 × 10¹¹ ions/cm²/s and 1 × 10¹⁵ ions/cm², respectively. The resistivity increased with the increasing fluence rate of the protons. FT/IR spectra have shown that a new band resulted from the appearance of N⁺-H due to the proton implantation.     

Evaluation method of the gait motion based on self-organizing map using the gravity center fluctuation on the sole

This paper describes the evaluation method of the gait motion in walk rehabilitation. We assume that the evaluation consists of the classification of the measured data and the prediction of the feature of the gait motion. The method may enable a doctor and a physical therapist to recognize the condition of the patients more easily, and increase the motivation of patient further for rehabilitation. However, it is difficult to divide the gait motion into discrete categories, since the gait motion continuously changes and does not have the clear boundaries. Therefore, the self-organizing map (SOM) that is able to arrange the continuous data on the almost continuous map is employed in order to classify them. And, the feature of the gait motion is predicted by the classification. In this study, we adopt the gravity-center fluctuation (GCF) on the sole as the measured data. First, it is shown that the pattern of the GCF that is obtained by our developed measurement system includes the feature of the gait motion. Secondly, the relation between the pattern of the GCF and the feature of the gait motion that the doctor and the physical therapist evaluate by visual inspection is considered using the SOM. Next, we describe the prediction of following features measured by numerical values: the length of stride, the velocity of walk and the difference of steps that are important for the doctor and the physical therapist to make a diagnosis of the condition of the gait motion in walk rehabilitation. Finally, it is investigated that the position of a new test data that is arranged on the map accords with the prediction. As a consequence, we confirm that the method using the SOM is often useful to classify and predict the condition of the patient.     

Rapid method for determination of β-carotene in foods using ultra high performance liquid chromatography

The ultra high performance liquid chromatography (u-HPLC) method for determination of β-carotene in foods was validated in terms of precision, accuracy, and linearity. The u-HPLC separation was performed on a reversed column C₁₈ (particle size 2 μm, i.d. 2 mm, length 50 mm), followed by ultra violet (UV) detection at 450 nm. The recovery of β-carotene was more than 84.4% and the limit of detection and limit of quantitation of u-HPLC analysis were 0.28 and 0.85 μg/mL for β-carotene with butylated hydroxytoluene (BHT) and 0.62 and 1.89 μg/mL for β-carotene without BHT, respectively. The calibration graph for β-carotene was linear from 0.1 to 25.0 μg/mL for u-HPLC. The intra- and interday precisions (relative standard deviations) were <7.5 and <7.8%, respectively. Benefits of u-HPLC analysis of β-carotene in foods is reduction of the analysis time to approximately 1/4, saving the volume of solvent to approximately 1/15. It seems that u-HPLC can offer significant improvements in speed, sensitivity, and resolution compared with conventional HPLC, this bodes well for future applications.     

Molecular cloning, testicular postnatal expression, and oocyte-activating potential of porcine phospholipase Czeta

The molecular mechanism by which sperm triggers Ca2+ oscillation, oocyte activation, and early embryonic development has not been clarified. Recently, oocyte activation has been shown to be induced by sperm-specific phospholipase Czeta (PLCzeta). The ability of PLCzeta to induce oocyte activation is highly conserved across vertebrates. In the present study, porcine PLCzeta cDNA was identified and the nucleotide sequence was determined. The expression pattern of porcine PLCzeta mRNA during the period of postnatal testicular development was shown to be similar to that of mouse PLCzeta. PLCzeta mRNA expression in the pig and mouse was detected only in the testes when the elongated spermatids had differentiated, and was detected from day 96 after birth in the pig. Histological examination of porcine testis during the period of postnatal development revealed the presence of spermatozoa from day 110 after birth. These findings suggest that the synthesis of PLCzeta mRNA starts when spermiogenesis is initiated. Microinjection of porcine PLCzeta complementary RNA into porcine oocytes demonstrated that porcine PLCzeta has the ability to trigger repetitive Ca2+ transients in porcine oocytes similar to that observed during fertilization. It was also found that porcine PLCzeta cRNA has the potential to induce oocyte activation and initiate embryonic development up to the blastocyst stage.     

Dielectrophoretic fabrication and characterization of a ZnO nanowire-based UV photosensor

Wide-gap semiconductors with nanostructures such as nanoparticles, nanorods, nanowires are promising as a new type of UV photosensor. Recently, ZnO (zinc oxide) nanowires have been extensively investigated for electronic and optoelectronic device applications. ZnO nanowires are expected to have good UV response due to their large surface area to volume ratio, and they might enhance the performance of UV photosensors. In this paper, a new fabrication method of a UV photosensor based on ZnO nanowires using dielectrophoresis is demonstrated. Dielectrophoresis (DEP) is the electrokinetic motion of dielectrically polarized materials in non-uniform electric fields. ZnO nanowires, which were synthesized by nanoparticle-assisted pulsed-laser deposition (NAPLD) and suspended in ethanol, were trapped in the microelectrode gap where the electric field became higher. The trapped ZnO nanowires were aligned along the electric field line and bridged the electrode gap. Under UV irradiation, the conductance of the DEP-trapped ZnO nanowires exponentially increased with a time constant of a few minutes. The slow UV response of ZnO nanowires was similar to that observed with ZnO thin films and might be attributed to adsorption and photodesorption of ambient gas molecules such as O(2) or H(2)O. At higher UV intensity, the conductance response became larger. The DEP-fabricated ZnO nanowire UV photosensor could detect UV light down to 10?nW?cm(-2) intensity, indicating a higher UV sensitivity than ZnO thin films or ZnO nanowires assembled by other methods.     

(100)MgO/Fe过渡层对半金属Fe3O4薄膜磁性能的影响（英文）

Fe3O4具有理论100%自旋极化率、高居里温度(858K),是能在室温下应用到自旋器件中的半金属材料。本研究采用对靶直流磁控溅射的方法制备了(100)MgO/Fe种子层,在此种子层上通过调节溅射工艺条件,得到了(100)晶向的Fe3O4薄膜。用XRD和TEM确认了反尖晶石相和(100)优先取向。采用VSM测试了样品的磁滞回线。结果表明,加入(100)MgO/Fe种子层后,Fe3O4薄膜的结构取向由随机排列转变到(100)优先取向,Fe3O4薄膜的磁性能发生了改变,具有了一定的垂直磁性能,AFM显示薄膜具有平整的平面,这利于通过加外加交换耦合薄膜来调节薄膜的磁性能,从而对自旋器件的应用有意义。