Three-dimensional vector holograms in anisotropic photoreactive liquid-crystal composites

In this paper, we describe the principle of the three-dimensional vector holograms formed in anisotropic recording medium. The polarization states of the interference light are three-dimensionally modulated due to both the polarization interference and optical anisotropy in the recording medium. The electric field of the polarized light reorients the director and forms the three-dimensional vector hologram in anisotropic photoreactive liquid-crystal composites. The theoretical consideration reveals the formation mechanism and optical characteristics of the resultant three-dimensional vector holograms.     

Three-dimensional architecture of virus-packed tubule

When rice dwarf virus (RDV), a member of the Reoviridae family, infects leafhopper cells, formation of protruding tubules composed of nonstructural viral protein Pns 10 can be observed. We examined the three-dimensional (3D) structure of these tubules containing RDV particles using electron tomography. The thin section of RDV-infected leafhopper vector cells in monolayers was subjected to double-tilt tomography. The tomographic 3D map provides a more reliable estimation of the real dimensions of the structure compared with the 2D image of the thin section. Docking of particle models made from atomic coordinates of RDV into the tomogram revealed that the inner diameter of the tubule was close to the outer diameter of the RDV particle. Fourier-transform of the reconstituted tubule image from the purified Pns 10 protein in vitro revealed a helical structure of the tubule.     

Relations between tooth enamel dose and organ doses for electron spin resonance dosimetry against external photon exposure

An analysis of doses to tooth enamel and to organs was carried out to develop a method that can predict the organ doses and the effective dose by electron spin resonance (ESR) dosimetry using tooth samples for external photon exposure. Absorbed dose to tooth enamel and organ doses were obtained by Monte Carlo calculations using the EGS4 code in combination with a mathematical human model with a newly defined teeth part. The calculations gave quantitative relations between tooth enamel dose and organ doses for some cases of external photon exposure. It was also found that tooth enamel dose depends more significantly on energy of incident photons than the other organ dose or the effective dose. The obtained data are to be useful for the assessment of individual dose in past exposure events by the ESR dosimetry using tooth enamel.     

Effect of gas introduction position on substrate etching by means of Ar-dominated graphite-cathodic-arc plasma beam in μT-FAD

Substrate etching by means of Ar-mixed graphite-cathodic-arc plasma beam was investigated in a newly-developed compact-type μT-FAD. The surface level and roughness change were measured as a function of the Ar gas flow rate, when Ar gas was introduced into the arc generation zone and in the vicinity of the substrate. When Ar gas was introduced to the arc generation zone, the etching rate was lower but the surface was relatively not roughened. When Ar gas was introduced in the vicinity of the substrate, the etching rate was higher but the surface was roughened. At the same gas flow rate (and pressure), the substrate was etched more than three times faster when Ar gas was introduced into the arc generation zone than to the vicinity of the substrate. After measuring the discharge and plasma conditions, the results were considered to be caused by the difference in the amount of plasma transported to the substrate.     

Photorefractivity in polymer dissolved liquid crystal composites composed of low-molecular-weight nematic liquid crystals and copolymer comprising mesogenic side groups

This paper describes the photorefractive effect of the liquid crystalline composite materials comprising low-molecular-weight nematic liquid crystals (L-LC), copolymer with mesogenic side groups and a small amount of photosensitizer. Copolymers with four kinds of mesogenic side groups were investigated with respect to the compatibility between the L-LC and the copolymer and the photorefractivity of the composites. Two of them could be miscible with L-LC and the composite exhibited LC phase even though the copolymer itself did not show a LC phase. High gain coefficients (> cm^K1) under the low applied dc electric field (<1V/mm) was observed when the composites showed a mesophase without any macroscopic phase separation.     

Heterogeneous nucleation and growth mechanism on hydrophilic and hydrophobic surface

Heterogeneous nucleation and nucleation period of calcium carbonate on the mica and the highly oriented pyrolytic graphite (HOPG) substrate have been investigated. Calcium carbonate was prepared by the reaction of calcium nitrate solution with sodium carbonate solution. In the reaction crystallization of calcium carbonate, calcite and vaterite were nucleated on the both substrates. We counted the number of crystalline calcium carbonate on the substrates obtained from various initial supersaturations of calcium carbonate. The number of crystals on the mica surface was much higher than on the HOPG surface. Additionally, the number of crystals on the mica was greatly affected by changing of initial supersaturation. In order to explain the difference between the mica and the HOPG surface, a possible model for the nucleation period of calcium carbonate has been discussed. The surface crystallization on the mica and the HOPG could be described by considering the supersaturation in the bulk solution and in the vicinity of substrate, separately.     

Novel charge neutralization techniques applicable to wide current range of FIB processing in FIB-SEM combined system

FIB-induced charging is one of the most critical issues for achieving successful circuit modifications of LSI. We have developed novel charge neutralization techniques applicable to a wide current range (from pico to nanoampere-order) of FIB processing in a FIB-SEM combined system. The method utilizes a 500 eV focused electron beam instead of an electron shower, and also a combination of microprobing and FIB-assisted deposition to make a current path from FIB processing point to the grounded microprobe. The effects of our techniques on charge neutralization capability were investigated using electrically erasable-programmable read-only memory devices and n-MOS transistors. For the low FIB current condition of less than 500 pA, it is found that the focused electron beam prevents threshold voltage shifts of both irradiated and neighboring transistors, and that the ratio of electron to ion beam currents is a key parameter to achieving effective charge neutralization. We also demonstrated that the combined method of microprobing and FIB-assisted deposition prevents parameter shifts of transistors even for high-current (nanoampere-order) FIB irradiation. Moreover, we evaluated the upper-limit resistance of the current path formed by FIB-assisted carbon deposition to prevent charging induced by a given FIB current.     

The influence of stud bumping stress on device degradation in scaled MOSFETs

This paper presents the effect of area bumping on device degradation in scaled metal-oxide-semiconductor field-effect transistors (MOSFETs). We have investigated the gate channel length dependence of g_m degradation after stud bumping above the MOSFETs and changes in the charge pumping currents for those devices. The von Mises’s equivalent stress is used to simulate the distribution of mechanical stress at the gate edges. From the relationship between the distribution of the von Mises’s equivalent stress and the change in the charge pumping currents after stud bumping, we show that stress concentrates within 0.1 μm of the gate edges. Furthermore, by estimating the amount of increased interface-state density we predicted that stud bumping stress greatly influences the device degradation of scaled MOS devices.     

Differential interference contrast microscope with differential detection for optimizing image contrast

A laser scanning differential interference contrast microscope using a differential detection method is proposed. This microscope permits observers to control the differential image contrast with a simple operation. Utilizing this function, the observers are capable of obtaining the optimized differential image whose contrast is most favorable for observation. A simple theoretical analysis and experimental considerations are described.     

Rapid change of stresses in thickness direction in long orthotropic tube under internal pressure and axial load

Exact solution for long orthotropic tube under internal pressure and axial load suggests the existence of very dangerous combinations of elastic properties. We demonstrate that such elastic properties can be thermodynamically stable. Close to a dangerous combination, stress components change very rapidly in radial direction, resulting in huge peak stresses exceeding the membrane theory predictions by several orders of magnitude, even for relatively thin-walled tubes. Another manifestation of this effect is extreme sensitivity of peak stresses to variations in elastic properties. Away from the critical condition the anomaly in stress distribution disappears and this can be the key point in the design of related structures. The rapid change of stresses in thickness direction is attributed to the auxetic property (negative Poisson’s ratio) of highly anisotropic material of the tube. As an example, we consider the filament wound tube with closed ends under internal pressure and demonstrate that, for highly anisotropic fiber-reinforced plastic, winding with angle close to 45° is potentially dangerous.