Grazing Incidence X-ray Diffraction Study on Surface Crystal Structure of Polyethylene Thin Films

Summary Crystal structure in thin films of melt-crystallized and annealed polyethylene (PE) was examined by grazing incidence X-ray diffraction measurements. Choosing appropriate incident angles of X-rays to the films, surface and bulk molecular aggregation states were successfully extracted. Consequently, it was found that chain packing structure in the surface region was different from that in the bulk one. Based on paracrystalline analysis for the (110) reflection and its higher-order ones of PE orthorhombic crystal, it was clarified that the ordering for the crystalline lattice was lower in the surface region. Also, apparent crystallinity in the surface was lower than the bulk one. These results indicate that disordered crystallites were preferentially formed in the surface region.     

Bringing out the Potential of Wild-type Cytochrome P450s using Decoy Molecules: Oxygenation of Nonnative Substrates by Bacterial Cytochrome P450s

To bring out the potential of wild-type cytochrome P450s, we have developed a series of “decoy molecules” to change their high substrate specificity without any mutagenesis. Decoy molecules are inert dummy substrates with structures that are very similar to those of natural substrates. The decoy molecules force long-alkyl-chain fatty acid hydroxylases (P450_BSβ, P450_SPα, and P450BM3) to generate the active species and to catalyze oxidation of various substrates other than fatty acids. Interestingly, the catalytic activity was highly dependent on the structure of decoy molecules. Furthermore, the enantioselectivity of reactions catalyzed by P450_BSβ and P450_SPα was also dependent on the structure of decoy molecules. The decoy molecule system allows us to control reactions catalyzed by wild-type enzymes by designing decoy molecules.     

Stabilization of a fully superconducting,damperless generator by excitation control

The development of ultrafine filaments superconductors for 50/60 Hz makes possible a fully superconducting generator which has superconducting field windings and armature windings. By omitting dampers and narrowing gaps between the field and the armature windings, the size and the weight of the fully superconducting generator can be drastically decreased. However, the damperless generator is inherently unstable and thus must be stablized by an appropriate method. We have investigated a method of stabilizing the generator in which the excitation voltage of the field winding is controlled by the state value feedback technique. The state values of the system are estimated by a state-value observer and the feedback constants are determined according to optimal control theory. It is shown that this method is effective in stabilizing a fully superconducting, damperless generator.     

Measurement of a cross-sectional profile of a thread gauge using a sinusoidally vibrating interference pattern

A sinusoidally vibrating interference pattern (SVIP) is used as an exact spatial scale in order to measure a cross-sectional profile of a thread gauge. The SVIP is projected on the thread gauge surface, and lights diffracted and reflected from the end points of the thread gauge surface are extracted by spatial frequency filtering in an imaging system to make an image of the end points whose positions are decided by the peak positions of amplitude distributions in the image. The coordinates of the end points or the cross-sectional profile of the thread gauge is obtained from the phases measured at the positions of the end points, phase distribution of the SVIP on a CCD image sensor, and the pixel positions of the CCD image sensor.     

Low-resistivity poly-metal gate electrode durable forhigh-temperature processing

A new low-resistivity poly-metal gate structure, W/WSiN/poly-Si, is proposed, A uniform ultrathin (<1 nm) WSiN barrier layer was formed by annealing a W(100 nm)WN_x(5 nm)/poly-Si structure. The W/WSiN/poly-Si structure was found to be thermally stable even after annealing at 800°C. The sheet resistivity of the W(100 nm)/WN_x (5 nm)/poly-Si(100 nm) structure is as low as 1.5 Ω∥□ and independent of line-width from 0.52 μm to 0.12 μm. The sheet resistivity of this layer structure is 40% lower than that of the W(100 nm)/TiN(5 nm)/poly-Si structure. In addition, an equivalent circuit simulation showed that the measured contact resistivity of W and poly-Si in the W/WSiN/poly-Si system did not affect the gate RC delay time. Finally, a process integration of the poly-metal gate electrode is discussed. A SiN capped poly-metal structure was demonstrated     

Double sinusoidal phase-modulating distributed-Bragg-reflector laser-diode interferometer for distance measurement

A previously proposed double sinusoidal phase-modulating (DSPM) laser-diode interferometer measures distances larger than a half-wavelength by detecting modulation depth. Although it requires a vibrating mirror to provide the second modulation to the interference signal, such vibrations naturally affect measurement accuracy. We propose a static-type DSPM laser-diode interferometer that uses no mechanical modulation. Our experimental results indicate a measurement error of +/- 1.6 microm.     

Double-grating interferometer for measurement of cylinder diameters

We describe a double-grating interferometer for the measurement of cylinder diameters. The unique characteristic of this interferometer is that one can freely change the period of the interference fringes by turning the grating, which permits the measurement range of the interferometer also to be changed freely according to the cylinder diameter to be measured. A clear image of the cylinder can be obtained because the aperture diaphragm blocks the beams diffracted from the edge of the cylinder. The outside and inside diameters of the M4 x 0.7 mm hand tap are measured with this double-grating interferometer.     

Direct‐connected multiple current‐source converters for SMES system

The superconducting magnetic energy storage (SMES) system would be a valuable system for power line stabilization. It would increase stability by supporting peak energy and compensating generation shortage. With the development of a large‐capacity GTO thyristor suitable for 20‐MW‐level power conversion systems, it is possible to control the four‐quadrant real power (P) and the reactive power (Q) condition by self‐commutated power converters with high performance. This paper describes a new direct‐connected multiple current‐source converter, and also explains suitable control strategies for the pilot plant of an SMES system. The feasibility of the control strategies is demonstrated by EMTP simulation results. © 2000 Scripta Technica, Electr Eng Jpn, 133(1): 87–96, 2000