Numerical studies on time-domain responses of on-off-keyed modulated optical signals through a dense fog

We present a numerical technique to simulate the propagation characteristics of an on-off-keyed modulated optical signal through fog. The on-off-keyed modulated light (a square wave) is decomposed into a finite number of harmonic components, and a numerical solution for the vector radiative transfer equation is obtained for each harmonic that corresponds to the modulation frequency. With this method we study the distortion and the pulse spread in the received signal due to attenuation and scattering. We investigate the propagation characteristic of the modulated signal with different communication system parameters. This information can be used to study communication channel reliability.     

Interfacial properties of a direct bonded Nd-doped YVO4 and YVO4 single crystal

Laser crystal bonding of a neodymium-doped yttrium orthovanadate (Nd : YVO₄) and a non-doped yttrium orthovanadate (YVO₄) crystal as a cold finger has been demonstrated. Instead of a traditional chemical treatment, a newly developed dry etching process was applied to the preparation for contact of mechanically polished surfaces. In the subsequent heat treatment process, stable heating at 873 K was required to prevent precipitation at the bonded interface. The bonded interface of 3 mm×3 mm was investigated by optical scattering and wavefront distortion measurements. The scattering density around the bonded interface was less than 4.6×10⁶/cm³ and the wavefront distortion caused by the bonded region was assumed to be around 0.04 at 633 nm. Additional magnified inspection showed that atoms in the bonded region were well arranged with the same regularity as the bulk crystal. The diffusion coefficient of Nd³⁺ ions in the YVO₄ crystal was estimated at 2.3×10^–23 m²/s at 873 K.     

The mechanism of sperm-oocyte fusion in mammals

Sperm-oocyte fusion is one of the most impressive events in sexual reproduction, and the elucidation of its molecular mechanism has fascinated researchers for a long time. Because of the limitation of materials and difficulties in analyzing membrane protein-protein interactions, many attempts have failed to reach this goal. Recent studies involving gene targeting have clearly demonstrated the various molecules that are involved in sperm-oocyte binding and fusion. Sperm ADAMs (family of proteins with a disintegrin and metalloprotease domain), including fertilin alpha, fertilin beta and cyritestin, have been investigated and found to be important for binding rather than for fusion and painstaking studies have raised suspicions that their putative receptors, oocyte integrins, are necessary for the sperm-oocyte interaction. Recently, several studies have focused the spotlight on CD9 and glycosylphosphatidylinositol (GPI)-anchored proteins on oocytes, and epididymal protein DE on sperm, as candidate molecules involved in sperm-oocyte fusion. Lack of, or interference with the function of, these proteins can disrupt the sperm-oocyte fusion without changing the binding. In this review we highlight the candidate molecules involved in the sperm-oocyte interaction suggested from the recent progress in this research field.     

Oligoalginate recognition and oxidative burst play a key role in natural and induced resistance of sporophytes of laminariales

Forty-five species of brown algae (Phaeophyceae) were surveyed for their capacity to respond by an oxidative burst to challenges with alginate oligosaccharides. Intertidal frondose brown algae (Fucales) constitutively released high quantities of peroxide. The capacity to recognize oligoguluronates and to react with an oxidative burst was confined to alginate-rich taxa with complex thallus morphology, epitomized by the sporophytes of Laminariales. When kelp sporophytes were impaired in their capacity to perform an oxidative burst by the NAD(P)Hoxidase inhibitor diphenylene iodonium, they were readily degraded by their bacterial epiflora. Thus, in these algae, the oxidative response is an essential element of natural resistance. We also report on the establishment of a well-defined experimental system for investigations on kelp immunity, with Laminaria digitata as the host and its phaeophycean endophyte, Laminariocolax tomentosoides, as the pathogen. We found that an alginate-triggered oxidative burst significantly induces resistance in Laminaria digitata against infection. From these findings we infer that oligoalginate signals are important cues in the interaction between laminarialean kelps and potential pathogens.     

汽车发动机用无Co排气阀座圈材料的开发

烧结合金广泛地用于制作汽车发动机阀座圈（VSI）。就增高耐热与耐磨耗性能而言，在合金化设计上，烧结合金远比常规的锻钢与铸造合金灵活。特别足，一些高钻烧结材料由于耐磨耗与耐热性高而广泛用作排气阀座圈材料。鉴于近来将发动机的A／F比（空气／燃料比）调整到比常规的贫化（即空气／燃料比增高），排气阀座圈的工作环境趋于严酷。这种A／F比贫化的趋向旨在减少排出的废气和减低燃料消耗。另一方面。也需要不断地减少使用像钴之类环境负荷高的材料。同时，钴昂贵，减低钴含母有利于节省这些材料。这篇论文详细报道了无钴、无铅及有利于环境的排气阀座矧的开发与使用。     

Evaluation of corrosion fatigue crack propagation life at low-pressure steam turbine rotor groove

The corrosion fatigue crack propagation life of Christmas-tree type rotor groove with three hooks is studied. Each corner of the hook can be a candidate for crack initiation site therefore the condition where cracks initiate and propagate simultaneously at several hook corners must be considered. When a blade is inserted in the rotor groove, narrow gap is introduced unavoidably between the rotor groove and the blade root. The effect of this narrow gap on the crack behavior must also be considered. A procedure was presented to assess the crack initiation and propagation behavior under such a condition. Using the procedure, crack initiation and propagation behavior was evaluated for several gap conditions. It was revealed that the gap condition had little effect on the relation between crack depth at the third hook corner and life consumption ratio (ratio of loading cycle to final failure life). A corrosion fatigue test was performed using a rotor groove model specimen, and the results were compared with the evaluation results.     

Frictional property with preferred crystal orientation of platinum oxide and palladium oxide coatings synthesized by combinatorial sputter coating system

The combinatorial sputter coating system (COSCOS) has been newly developed, that can fabricate various kinds of coatings under precisely controlled lots of conditions such as selection of sputter gas and gas pressure, gas partial pressure, r.f. power, substrate temperature, distance between a substrate and a target, etc. COSCOS can also control the crystal preferred orientation of coatings which strongly affect those frictional property. Platinum oxide and palladium oxide coatings were synthesized by COSCOS, then the crystal structure was analyzed with X-ray diffraction spectroscopy and frictional properties of the coatings were measured by a tribometer at an atmospheric pressure.     

Development of nickel/metal-hydride batteries for EVs and HEVs

This paper is to introduce the nickel/metal-hydride (Ni/MH) batteries for electric vehicles (EVs) and hybrid electric vehicles (HEVs) developed and mass-produced by our company. EV-95 for EVs enables a vehicle to drive approximately 200 km per charge. As the specific power is extremely high, more than 200 W/kg at 80% depth of discharge (DOD), the acceleration performance is equivalent to that of gasoline fuel automobiles. The life characteristic is also superior. This battery gives the satisfactory result of more than 1000 cycles in bench tests and approximately 4-year on-board driving. EV-28 developed for small EVs comprises of a compact and light battery module with high specific power of 300 W/kg at 80% DOD by introducing a new technology for internal cell connection. Meanwhile, our cylindrical battery for the HEV was adopted into the first generation Toyota Prius in 1997 which is the world’s first mass-product HEV, and has a high specific power of 600 W/kg. Its life characteristic was found to be equivalent to more than 100,000 km driving. Furthermore, a new prismatic module in which six cells are connected internally was used for the second generation Prius in 2000. The prismatic battery comprises of a compact and light battery pack with a high specific power of 1000 W/kg, which is approximately 1.7 times that of conventional cylindrical batteries, as a consequence of the development of a new internal cell connection and a new current collection structure.     

Use of Double Wash-Coatings of Platinum and Zeolite Catalysts to Improve Selective Reduction of NOx by Hydrocarbons

The selective catalytic reduction by hydrocarbons (HC-SCR) of NO _x under lean conditions has been improved by the use of double-layered catalysts with a lower layer of Pt/SiO₂ and an upper layer of a zeolite such as H-, Ce-, and Cu-ferrierite (-FER). H-FER wash-coated over Pt/SiO₂ (H-FER//Pt/SiO₂) performed best among the samples examined. The promotional effect was attributed to the synergy of the oxidation catalyst (Pt/SiO₂) in converting NO into NO₂, which is more reactive to C₃H₆, and the HC-SCR catalyst (H-FER). Cu-FER//Pt/SiO₂ was also effective at widening the temperature window, but with this combination the performance was attributed to a simple summation of the activity of two HC-SCR catalysts that were active at different temperatures.     

采用Ni—Cr合金热喷涂延长连铸结晶器寿命

三岛光产所开发的Ni-Cr合金热喷涂结晶器,是通过对连铸结晶器表面喷涂Ni-Cr合金涂层,使其寿命达到原来镀Ni结晶器的3-6倍,本文介绍Ni-Cr合金热喷涂结晶器的特性、使用效果和使用上的注意点。