Modified silicone as new type of primary coat for optical fibre

It is confirmed that modified silicone is the most suitable for the primary coat of optical fibre. The modified silicone-coated fibre with a silicone buffer and a nylon jacket is found to have high mechanical strength and stable transmission characteristics.     

Dry formation of a fatty acid crystallized thin film and application as an electron beam resist

A crystalline fatty acid film was formed by vacuum evaporation and evaluated as an electron beam resist. For an actual process, a double-layer dry resist process using evaporated fatty acid and aluminium was proposed for fine pattern fabrication. A pattern of 4 μm lines and spaces was successfully fabricated.     

Pervaporation separation of water/ethanol mixtures through polysaccharide membranes. III. The permselectivity of the neutralized chitosan membrane and the relationships between its permselectivity and solid state structure

The separation of water/alcohol mixtures through chitosan membrane neutralized by various acids was investigated. The permselectivity of the neutralized chitosan membrane was affected by the species of acids and, only when neutralized by polybasic acids, was a marked increase of the selectivity observed and a high selectivity maintained for ion free mixtures. The marked increase of the selectivity could be explained by the contraction of the “holes” produced by the thermal motion of polymer chains due to the conformation change of chitosan molecule caused by the neutralization. The conformation change was confirmed by the analysis of the solid state structure of the neutralized chitosan using CP/MAS ¹³C-NMR.     

Moment-rotation relationship considering flattening of pipe due to pipe whip loading

It is important to take flattening of pipe into consideration in order to obtain pipe deformation due to pipe whip loading. An experimental relationship between the flattening of pipe and the pipe surface strain was used to derive the moment-rotation relationship of whipping pipe. The derived moment-rotation relationship was used to calculate the pipe strain in the pipe whip tests using a simplified energy balance method. A comparatively good agreement was obtained between the analytical and experimental results.     

Vacuum lithography using plasma polymerization and plasma development

A completely dry lithography has been proposed which involves plasma polymerization of methyl methacrylate (MMA) and plasma development with CCl₄. It was called vacuum lithography because all processes were performed in a vacuum. However, the developed pattern had a lower resolution than patterns produced by conventional lithography with a wet process. After several technical refinements, the quality of the resist and the developed pattern was markedly improved. In this paper, recent results will be reported.A gas-flow-type reactor was used instead of a bell-jar-type reactor because the morphology of plasma-polymerized MMA (PPMMA) varied with each experimental run which was performed with the same gas and discharge parameters. The monomer vapour was introduced downstream of the argon discharge, and the polymerized film was formed on the substrate placed further downstream in the mixed gas.The development of pattern was performed by etching with an Ar-O₂ mixture and with hydrogen gas instead of CCl₄ gas, because the etching rate of the resist was too high in a CCl₄ plasma and a clear pattern was not obtained. The evaluated sensitivity and γ value of PPMMA were 1000 μC cm^?2 and 1 respectively. MMA containing 5% tetramethyltin was also used as a monomer gas for plasma polymerization downstream of the argon discharge. In this case the sensitivity and γ value were 10 μC cm^?2 and 2 respectively.     

Highly Efficient Persistent Room-Temperature Phosphorescence from Heavy Atom-Free Molecules Triggered by Hidden Long Phosphorescent Antenna

Persistent (lifetime > 100 ms) room-temperature phosphorescence (pRTP) is important for state-of-the-art security and bioimaging applications. An unclear relationship between chromophores and physical parameters relating to pRTP has prevented obtaining an RTP yield of over 50% and a lifetime over 1 s. Here highly efficient pRTP is reported under ambient conditions from heavy atom-free chromophores. A heavy atom-free aromatic core substituted with a long-conjugated amino group considerably accelerates the phosphorescence rate independent of the intramolecular vibration-based nonradiative rate from the lowest excited triplet state. One of the designed heavy atom-free dopant chromophores presents an RTP yield of 50% with a lifetime of 1 s under ambient conditions. The afterglow brightness under strong excitation is at least 10⁴ times stronger than that of conventional long-persistent luminescence emitters. Here it is shown that highly efficient pRTP materials allow for high-resolution gated emission with a size of the diffraction limit using small-scale and low-cost photodetectors.     

Joining of silicon nitride ceramics by hot pressing

The joining of hot-pressed silicon nitride ceramics, containing Al₂O₃ and Y₂O₃ as sintering aids, has been carried out in a nitrogen atmosphere. Uniaxial pressure was applied at high temperature during the joining process. Polyethylene was used as a joining agent. Joining strength was measured by four-point bending tests. The effects of joining conditions such as temperature (from 1400 to 1600°C), joining pressure (from 0.1 to 40 MPa), holding time (from 0.5 to 8 h) and surface roughness (R _max) of the joining couple (about 0.12, 0.22 and 1.2m) on the joining strength were examined. The joining strength was increased with increases in joining temperature, joining pressure and holding time. Larger surface roughness caused lower joining strength. The higher joining strength was attributed to a larger true contact area. The area was increased through plastic deformation of the joined couple at elevated temperatures. The highest joining strength attained was 567 MPa at room temperature, which was about half the value of the average flexural strength of the original body. The high temperature strength measured at 1200° C did not differ very much from the room-temperature value.