Dependence of aerodynamic characteristics and flow pattern on surface structure of a baseball

In this report, the aerodynamic characteristics, such as lift and drag, of an official rubber baseball are studied experimentally by comparing the characteristics of a sphere having a smooth surface and those of spheres having different surface structures. In addition, the flow velocity distribution is measured quantitatively using the spark tracing method. From the obtained results, the flow patterns for these baseballs and the flow mechanism around a sphere have been clarified.     

Synthesis and crosslinking reaction of poly(hydroxyurethane) bearing a secondary amine structure in the main chain

This article describes the polyaddition of bifunctional five‐membered cyclic carbonates and diethylenetriamine. The polyaddition proceeded via the selective addition of the primary amino group to the cyclic carbonates to give poly(hydroxyurethane)s bearing a secondary amine structure in the main chain. The resulting poly (hydroxyurethane) having a secondary amine structure was crosslinked by a reaction with a bifunctional dithiocarbonate to give a networked poly(hydroxyurethane–mercaptothiourethane). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5899–5905, 2005     

Observation of coherent X-ray production by 800-MeV electrons in a periodic triple-crystal target

The production of coherent x radiation by 800-MeV electrons in a target consisting of three 16-μm silicon crystals is investigated at the Tomsk synchrotron. The target structure makes it possible to observe from each crystal in turn, as the target is rotated, the radiation due to the summation of parametric x radiation (PXR) and the diffracted resonance transition radiation (DRTR) produced at the surfaces of the preceding crystals. The orientational dependence obtained shows that the contribution of the DRTR increases with the number of the crystal in the series, so that the angular density of the DRTR from the third crystal is approximately 1.7 times higher than the density of the PXR. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 8, 594–599 (25 April 1997)     

Precise measurement of the magnetic moment of17F(I x =5/2+,T 1/2=64.5 s) and its hyperfine interactions in ionic crystals

Hyperfine interactions of β-emitting¹⁷F implanted in single crystals of NaF and CaF₂ were studied. The nuclear magnetic moment of theT ^π=5/2⁺ state was determined with an improved precision to be |μ(¹⁷F;π=5/2⁺,T _1/2=64.5s|=4.72130±0.00025. nm. Isoscalar magnetic moments of the doubly closed shell ±1 nucleon nuclei around mass number 16 were derived and the effective nucleon mass in the nucleus was discussed.     

Assay of cholesterol 7 alpha-hydroxylase utilizing a silica cartridge column and 5 alpha-cholestane-3 beta, 7 beta-diol as an internal standard

A simplified and accurate assay of cholesterol 7 alpha-hydroxylase activity using 5 alpha-cholestane-3 beta,7 beta-diol as an internal standard is described. Endogenous microsomal cholesterol was used as the substrate. Following incubation and addition of the internal standard, lipids extracted from the incubation mixture were applied to Bond-Elut silica cartridge columns. 7 alpha-Hydroxycholesterol, 7 beta-hydroxycholesterol, 7-ketocholesterol and the internal standard were quantitatively recovered by eluting the column with 6 ml of benzene-ethyl acetate (2:3, v/v) after removal of cholesterol with 6 ml of benzene-ethyl acetate (9:1, v/v). After trimethylsilylation, the mass of 7 alpha-hydroxycholesterol was determined by capillary gas chromatography with selected-ion monitoring. The method permits a faster, easier and more sensitive determination of the activity of cholesterol 7 alpha-hydroxylase in small samples.     

High-Efficiency ZnCdSe/ZnSSe/ZnMgSSe Green Light-Emitting Diodes

Green light-emitting diodes (LEDs) were fabricated employing a ZnCdSe/ZnSSe triple quantum-well (TQW) active region surrounded by ZnMgSSe cladding layers grown on an n-type (100) GaAs substrate by molecular beam epitaxy (MBE). A 3.5 mW pure green emission was observed for the surface-emitting LED device at a peak wavelength of 513.3 nm (2.415 eV) with a spectral half-width of 11.7 nm (55 meV) under a 20 mA (4.6 V) direct current at room temperature (25°C). These correspond to an external quantum efficiency of 7.2%, a power conversion efficiency of 3.8%, a luminous current efficiency of 66 lm/A, and a luminous efficiency of 14 lm/W.     

Scattering of a plane wave from a periodic random surface: a probabilistic approach

This paper deals with a probabilistic formulation of the wave scattering from a periodic random surface. When a plane wave is incident on a random surface described by a periodic stationary stochastic process, it is shown by a group-theoretic consideration that the scattered wave may have a stochastic Floquet form, i.e. a product of a periodic stationary random function and an exponential phase factor. Such a periodic stationary random function is then written by a harmonic series representation similar to a Fourier series, where Fourier coefficients are mutually correlated stationary processes instead of constants. The mutually correlated stationary processes are represented by Wiener - Hermite functional series with unknown coefficient functions called Wiener kernels. In case of a slightly rough surface and TE wave incidence, low-order Wiener kernels are determined from the boundary condition. Several statistical properties of the scattering are calculated and illustrated in figures.     

PIV measurement of toner particle motion in a micro-gap in the development process of electrophotography

In the development process of electrophotography, charged dielectric toner particles move in a micro-gap between the photoreceptor and the development roller to form images by the action of electrostatic force. To improve image quality, it is important to clarify the toner particle motion and the effects of the electric field on this motion. In the present study, Particle Image Velocimetry (PIV) was applied to measure the toner particle motion and the results were compared to calculated results. It was confirmed that the toner velocity increased with increasing electric field intensity, and that the measurement results agreed with the calculated results. These results indicated the usefulness of PIV in analyzing toner particle motion in the development process.