One-dimensional self-assembly of alkoxy-capped silicon nanoparticles

We demonstrate here a novel method for self-assembling in dimensional alignment the alkoxy-capped silicon nanoparticles synthesized through a room-temperature chemical route. The alkoxy-capped silicon nanoparticles were prepared via a reduction of silicon tetrachloride with sodium-naphthalide and subsequent surface capsulation with 1-octanol monolayers. In the present method, a sublimation process, which was employed as a final purification process for removing the residual naphthalene, influenced significantly on the final morphology of the resultant nanoparticles. Scanning transmission electron microscope (STEM) confirmed the spherical nanoparticles on a holey carbon grid after sublimation process, while only the fibril-like morphology just before sublimation process. In the former sample, the resultant particle size was measured by STEM to be about 9.5 nm +/- 3.4 nm. On the other hand, in the latter sample, the fibril-like structures were shaped by self-assembled silicon nanoparticles in dimensional alignment. The diameters and lengths of the fibril-like assemblies were approximately measured to be 10 to 20 nm and over 5 microm, respectively.     

Studies of self-organization processes in nanoporous alumina membranes by small-angle neutron scattering

We performed studies of the self-organization processes in nanoporous alumina membranes at initial and late stages of aluminum anodization by using scanning electron microscopy (SEM) and small-angle neutron scattering (SANS). SEM observations indicated three stages in the self-organization of nanopores in alumina: (1) nucleation of random nanopores with a broad radius distribution, (2) narrowing the radius distribution and (3) slow evolution of the nanoporous structure towards ordering of nanopores into large domains. SANS studies revealed orientational correlation between ordered domains of nanopores, which is characterized by a small misorientation angle. For the samples with high aspect ratios of nanopores, the SANS patterns showed azimuthal smearing, which was attributed to the redistribution of nanopores between the domains during their growth.     

Comparative performance analysis of stroke correspondence search methods for stroke-order free online multi-stroke character recognition

For stroke-order free online multi-stroke character recognition, stroke-to-stroke correspondence search between an input pattern and a reference pattern plays an important role to deal with the stroke-order variation. Although various methods of stroke correspondence have been proposed, no comparative study for clarifying the relative superiority of those methods has been done before. In this paper, we firstly review the approaches for solving the stroke-order variation problem. Then, five representative methods of stroke correspondence proposed by different groups, including cube search (CS), bipartite weighted matching (BWM), individual correspondence decision (ICD), stable marriage (SM), and deviation-expansion model (DE), are experimentally compared, mainly in regard of recognition accuracy and efficiency. The experimental results on an online Kanji character dataset, showed that 99.17%, 99.17%, 96.37%, 98.54%, and 96.59% were attained by CS, BWM, ICD, SM, and DE, respectively as their recognition rates. Extensive discussions are made on their relative superiorities and practicalities.     

Development of a low-energy high resolution X-ray camera for high-energy gamma photon background environments

Although a high-energy gamma camera can obtain images of ¹³⁷Cs distribution by detecting the 662-keV gamma photons, its spatial resolution is reduced because high-energy gamma photons penetrate the edge of the pinhole collimator. To solve this problem, we developed a low-energy X-ray camera that detects the characteristic X-ray photons (32–37 keV) that are emitted from ¹³⁷Cs to obtain high resolution images. We used a 45 × 45 × 1-mm-thick NaI(Tl) scintillator that was encapsulated in 0.1-mm-thick aluminum and optically coupled to a 2-inch square, position sensitive photomultiplier tube (Hamamatsu Photonics, PSPMT:H12700 MOD) as an imaging detector. The imaging detector was encased in a 2-cm-thick tungsten alloy container and a pinhole collimator was attached to its camera head. The spatial resolution and sensitivity were ～5 mm full-width at half-maximum and ～0.6 cps/MBq for the 1.5-mm pinhole collimator 10 cm from the collimator surface, respectively. We administered 5 MBq of ¹³⁷Cs to a soybean seedling, imaged the distribution of radionuclides for six hours, and successfully obtained a high resolution image of it with our developed X-ray camera. We believe our camera will be a powerful tool for such ¹³⁷Cs imaging in plants.     

The effect of osmotic dehydrofreezing on the role of the cell membrane in carrot texture softening after freeze-thawing

To understand the protective mechanism of the osmotic dehydrofreezing technique on carrot texture after freeze-thawing, two mechanical texture parameters, fracture stress related to the cell wall and initial modulus related to the cell membrane, as well as cell membrane water permeability using PFG-NMR were evaluated. In particular, to understand the role of the cell membrane in texture alteration, tissue in which the cell membrane was exposed to chloroform vapor was used. Although dehydrofreezing protected texture from freezing damage, the effect was only observed with respect to fracture stress, with exhibited values close to those for raw tissue. However, there was no protective effect on initial modulus and water permeability, in which values did not differ from those of cell membrane-free tissue. More specifically, osmotic dehydrofreezing had no effect on the cell membrane induced by freeze-thawing.     

Development and validation of an HPLC-based screening method to acquire polyhydroxyalkanoate synthase mutants with altered substrate specificity

A rapid and convenient method for the compositional analysis of polyhydroxyalkanoate (PHA) was developed using high-performance liquid chromatography (HPLC) and alkaline sample pretreatment in a 96-well plate format. The reliability of this system was confirmed by the fact that a mutant with a D171G mutation of Aeromonas caviae PHA synthase (PhaC(Ac)), which gained higher reactivity toward 3-hydroxyhexanoate (3HHx), was selected from the D171X mutant library. Together with D171G mutant, several single mutants showing high reactivity toward 3HHx were isolated by the HPLC assay. These new mutants and double mutants combined with an N149S mutation were used to synthesize P(3-hydroxybutyrate-co-3HHx) in Ralstonia eutropha PHB(-)4 from soybean oil as carbon source, achieving higher levels of 3HHx fraction than the wild-type enzyme. Based on these results, the high-throughput screening system will serve as a powerful tool for exploring new and beneficial mutations responsible for regulating copolymer composition of PHA.     

PVDF actuator for high‐frequency fatigue test of thin‐film metals

This paper suggests a poly(vinylidene fluoride) (PVDF) piezoelectric diaphragm actuator used in a novel fatigue test method for thin metal films. A thin‐film metal specimen is stamped on top of the actuator using a stamping epoxy. As the actuator vibrates, the stress in the specimen increases until it fails under fatigue. A finite element model of the actuator is built, and its vibration amplitude is confirmed to be in a good agreement with experiment. Then, a model of the specimen is added to this model to simulate the vibration of the specimen for fatigue test. Stress analysis of the specimen at a driving voltage of 200 V_0−p confirms that this actuator can increase the stress in the specimen to near 1 GPa, which is high enough for the fatigue test of metals such as titanium. In the experiment, a thin‐film titanium specimen is stamped on top of the actuator which is then vibrated. The stress in the fatigue gauge on thin‐film specimen increased until the specimen failed under fatigue. This shows that the proposed PVDF actuator is suitable for the fatigue test of thin‐film metals such as titanium. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Controlled reduction of Cu to Cu with an N,O-type chelate under hydrothermal conditions to produce Cu2O nanoparticles

N,O-type organic chelates reduced coordinated Cu²⁺ ions under hydrothermal reaction conditions to produce Cu₂O/CuO nanoparticles. Chelates in which the N and O atoms are closely spaced produced smaller amounts of CuO nanoparticles, indicating their higher ability to reduce Cu²⁺ ions to Cu⁺ ions. [Cu(Gly)₂]² with the shortest ligand chain length produced only Cu₂O nanoparticles and, therefore, can be used as a single molecule precursor for the synthesis of Cu₂O nanoparticles.     

A 1.0-V 230-MHz column access embedded DRAM for portable MPEGapplications

This paper describes a 32-Mb embedded DRAM macro fabricated using 0.13-μm triple-well 4-level Cu embedded DRAM technology, which is suitable for portable equipment of MPEG applications. This macro can operate 230-MHz random column access even at 1.0-V power supply condition. The peak power consumption is suppressed to 198 mW in burst operation. The power-down standby mode, which suppresses the leakage current consumption of peripheral circuitry, is also prepared for portable equipment. With the collaboration of array circuit design and the fine Cu metallization technology, macro size of 18.9 mm² and cell efficiency of 51.3% are realized even with dual interface and triple test functions implemented     

Features of Transmission EBSD and its Application

Features of transmission electron backscatter diffraction (EBSD) observation with a standard EBSD (s-EBSD) detector are surveyed in this study. Heavily deformed Al and 8Cr tempered martensite transmission electron microscope (TEM) specimens were used for this study. It is shown that a specimen tilt angle of ~30°–40° in the opposite direction of the usual 70° and a smaller working distance in the range 4 mm–5 mm are recommended when using a s-EBSD detector. Specimen thickness and accelerating voltage (Acc.V) have a strong affect on the quality of transmission EBSD patterns and orientation maps. Higher Acc.Vs are generally recommended to get good quality orientation maps. In case of very thin specimens, lowering the Acc.Vs will give better results. In the observation of a thin film of an 8Cr tempered martensite steel specimen, it is confirmed that t-EBSD can provide images and detailed quantitative orientation data comparable with that obtained by TEM. It is also shown that small precipitates of Cr₂₃C₆ with sizes around 30 nm could be detected and their orientations measured.