Direct length comparison between regular crystalline lattice and SEM standard grating using dual tunneling unit STM

This paper presents a potential image processing method for calibrating the in-plane geometrical distortion of a scanning tunneling microscope (STM) image using a regular crystalline lattice, describes the assessment evaluation of comparative length measurement in the range of about 1 micrometer using a regular crystalline lattice as a reference scale and a dual tunneling unit-STM (DTU-STM) as a detector, and shows the results of direct length comparison between a scanning tunneling microscope (SEM) standard grating, whose pitch is 240 nm, and a regular crystalline lattice using a DTU-STM. The method is based on two-dimensional fast Fourier transform (FFT) analysis. The DTU- STM with one X-Y stage and two tunneling units independently controlled in the Z-axis direction has been utilized for comparative length measurement. To improve the measurement accuracy, the present method is used to process the raw images obtained from the DTU-STM. The results of assessment experiments, in which the cleaved surface of highly oriented pyrolytic graphite (HOPG) is used as a reference scale for measurement of lengths on the order of 1 micrometer, demonstrate the feasibility of the present image processing method and the comparative length measurement with sub-nanometer resolution using the DTU- STM. The value of the SEM standard grating pitch, which obtained from the direct length comparison with HOPG lattice spacing using the DTU-STM, was coincided with the value obtained from the conventional diffraction method within a error of 2 %.     

C32: Computations of Low-Energy Cages with Four-Membered Rings

C₃₂ cages built from four-, five-, six-, and seven-membered rings are computed. The computations are primarily performed with semiempirical quantum-chemical methods (AM1, PM3, SAM1), and altogether 199 cages are optimized. The energetics is further checked through ab initio HF SCF computations with the standard 3-21G basis set, and also by density functional theory at the B3LYP level in the standard 6-31G* basis set. All five levels of theory suggest a D_4d cage (two four-membered rings, eight pentagons, eight hexagons) as the lowest-energy structure. Temperature effects are treated in the terms of partition functions so that the entropy contributions are considered accordingly. The thermodynamic treatment points out five cages significantly populated at high temperatures. At very high temperatures the structure lowest in energy is not the most abundant isomer. There are just six conventional fullerenes C₃₂, built exclusively from pentagons and hexagons, however, only two of them show significant populations at high temperatures. The remaining three relatively stable cages contain at least one four-membered ring. No structure with a heptagon shows a non-negligible concentration at high temperatures. The study suggests that in the non-IPR region the quasi-fullerene cages with four-membered rings can in some cases be more important than the conventional fullerenes built from pentagons and hexagons only.     

Molecular dynamics simulation for the crystal structure of synthetic sugar-based bolaamphiphiles

We have performed molecular dynamics simulations for the crystals of synthetic sugar-based bolaamphiphiles with two D-galactosyl- or D-glucosylamine rings, using the Parrinello–Rahman–Nosé method with Dreiding force field to understand the origin of a bend structure of 1-galactosamino bolaamphiphile (Gal-10-Gal) in a crystalline phase. Intermolecular interaction energy between nearest neighbor molecules which arrange in a layer is larger than the energy between interlayer molecules. Intermolecular interaction (especially van der Waals and electrostatic interaction) between the Gal-10-Gal molecules within the layer contributes to stabilization of the crystal structure of Gal-10-Gal. Bending of the Gal-10-Gal molecule minimizes hydrogen bonding energy and electrostatic energy between the nearest neighbor Gal-10-Gal molecules.     

Influence of lattice polarity of nitrogen and aluminum doping on 4H-SiC epitaxial layer

We have reinvestigated the characteristics of N and Al doping on 4H-SiC epitaxial layer. It was found that thermally activated process and desorption process are aspects of the mechanism of the N incorporation to which attention should be paid. The process strongly depends on the lattice polarity and C/Si ratio. Thermally activated process dominates the N incorporation of the Si-face under the high C/Si ratio. Under the low C/Si condition, the desorption process dominates the N incorporation of the Si-face. For C-face, the desorption process dominates the N incorporation regardless of the lattice polarity and the C/Si ratio. Concerning Al doping, the desorption process dominates the Al incorporation without reference to the lattice polarity and the C/Si ratio.     

HCl gas monitoring based on a QCM using morpholine-functional styrene-co-chloromethylstyrene copolymer coatings

Quartz resonators coated with various compositions of poly(styrene-co-chloromethyl styrene) reacted with morpholine as adsorption sites were fabricated for simply but accurately monitoring HCl gas in air. The exposure of all resonators to HCl gas irreversibly decreased the oscillation frequencies, indicating that these devices can be used for one-shot detection of HCl gas. The chemical structure and composition of the copolymer affected the sensitivity. The largest sensitivity was obtained for the copolymer having 40.0 mol% CMSt composition cross-linked with 5.0 mol% DVB. The sensitivity was 0.1 ppm/Hz for 10-min sensor operation, demonstrating a ppm level of HCl detection, although great interference was produced by changes in the humidity.     

Development of a digital control system for high-performance pneumatic servo valve

Pneumatic servo systems are used in many fields, such as pneumatic robot systems or vibration isolation systems. To improve the controllability of the pneumatic servo system, a higher performance servo valve is needed.In the present paper, a pneumatic spool type servo valve having an air bearing and a high-resolution position sensor was developed. We attempted to achieve high-frequency, high-accuracy flow rate control by digitization of the controller. We present herein a control algorithm for digital control of this valve.The characteristics of this valve were measured and the natural frequency of the valve was clarified to be up to 300 Hz. The spool position accuracy and the dynamic characteristics of the developed servo valve are greatly improved compared to existing valves.     

Structures and gas permeabilities of poly(vinyl chloride)/oligo(dimethylsiloxane) blend membranes

A series of polymer blend membranes with several weight ratios of poly(vinyl chloride) (PVC) and oligo(dimethylsiloxane) (ODMS) were prepared and the permeation behaviors of O₂ and N₂ were studied. These components are only partially miscible to each other, leading to a phase separation. In order to improve the compatibility of these polymer blends, the use of a graft copolymer PVC-g-ODMS was explored. The gas permeation studies, the thermal analyses, and the microscopic observations were made on PVC-g-ODMS/ODMS blend membranes, and the results indicate that these blend membranes have rather high gas permeabilities together with good mechanical properties.     

Process optimization for the manufacturing of sheets with estimated balance between product quality and energy consumption

Reducing energy consumption and emissions are crucial environmental concerns. While industry requires high-quality sheet steel for forming, the production of this steel by the steel industry consumes huge amounts of electric energy and emits considerable CO₂. Conventionally, hot rolling process parameters have been determined empirically to achieve the desired mechanical properties, with the quality of the hot-rolled products having priority over energy consumption. We have developed a novel optimization system that evaluates both energy consumption in the sheet manufacturing process and the mechanical properties of the hot-rolled products. This paper describes the optimization of hot rolling strategies based on the estimation of energy consumption and prediction of mechanical properties.     

Cloning and analysis of the AWA1 gene of a nonfoaming mutant of a sake yeast

Almost all sake yeasts form a thick foam layer on sake mash during fermentation. To reduce the amount of foam, nonfoaming mutants were bred from foam-forming sake yeasts. To elucidate the mechanism of this foam formation, we have cloned a gene from a foam-forming sake yeast that confers foam-forming ability to a nonfoaming mutant. This gene, named AWA1, encodes a glycosylphosphatidylinositol (GPI) anchor protein that is localized to the cell wall and is required for cell surface hydrophobicity. In this paper, we describe the genomic analysis of the AWA1 gene in a nonfoaming mutant strain K701 derived from a foam-forming sake yeast strain K7. K701-AWA1 was cloned in a cosmid and its sequence was compared with that of K7-AWA1. Although the 5' half of K701-AWA1 was identical to that of K7-AWA1, the 3' half of K701-AWA1 was different from that of K7-AWA1, resulting in a loss of the C-terminal hydrophobic sequence of Awa1p. Since this sequence is considered to be required for the anchoring of Awa1p to the cell wall, K7-Awa1p could not confer both cell surface hydrophobicity and foam-forming ability to strain K701 cells. Since the change found in K701-AWA1 was not a point mutation but a larger scale event, we analyzed chromosome rearrangement by pulsed-field gel electrophoresis Southern blot analyses. The results suggest that the left subtelomeric region of chromosome IX in strain K7 was translocated to the AWA1 gene in chromosome XV by a nonreciprocal recombination.