Effect of titanium dioxide and 3.5% hydrogen peroxide with 405-nm diode laser irradiation on bonding of resin to pulp chamber dentin

This study was conducted to determine the effect of a 3.5% hydrogen peroxide solution containing titanium dioxide on bonding of resin to pulp chamber dentin. Extracted bovine anterior teeth were allocated to three groups of ten teeth each. The coronal labial pulp chamber dentin was exposed and bleached with 3.5% hydrogen peroxide with titanium dioxide with 405-nm diode laser irradiation for 15 min (Group 1); 30% hydrogen peroxide with halogen lamp irradiation for 15 min (Group 2); and distilled water for 15 min (Group 3). After bleaching, the pulp chamber dentin was prepared for composite resin bonding and the interface between the resin and dentin was observed by scanning electron microscopy. The microtensile bond strength (μTBS) and failure patterns were determined. The μTBS values (mean ± SD) were: 17.28 ± 5.79 MPa (n = 36), 0 MPa, and 26.50 ± 9.83 MPa (n = 36) in Groups 1, 2, and 3, respectively. The μTBS in Group 3 was significantly higher than that in Group 1 (P < 0.05). Hybrid layers and resin tags were clearly observed at the interface in Groups 1 and 3, but not in Group 2. Adhesive failure was mainly observed in Group 1, whereas dentin failure was the main failure pattern in Group 3.     

Flow of a viscous fluid past a flexible membrane at low Reynolds numbers

The numerical calculation of a steady two-dimensional viscous flow past a flexible membrane is treated. Both edges of the membrane are fixed in the flow and its chord is set normal to the flow. The Navier-Stokes equation in terms of the stream function and the vorticity is transformed to the body fitted coordinate system. The numerical calculations, based on a finite difference method and relaxation method, are carried out for several values of the membranes tension for cases when the Reynolds numbers are 5, 10 and 20. It is found that two different shapes of the membranes are possible at a given value of tension and Reynolds number: one with a small deformation, and the other with a large deformation. Two vortices appear in the concave region of the membrane if its deformation increases beyond a certain extent.     

Multiple dual-wavelengths fiber ring laser utilizing a phase-only sampled fiber Bragg grating with multiple phase-shifts inserted

A simple technique to multiply the lasing wavelength in a semiconductor optical amplifier (SOA)-based fiber ring laser is proposed and demonstrated, which is based on the utilization of a multiple phase-shifts sampled fiber Bragg grating (FBG). Tunability for the wavelength spacing within all dual-wavelengths has also been demonstrated by changing the positions of phase-shifts. Moreover, more than 20 dual-wavelengths fiber lasers with a 3-dB linewidth of 0.017 nm and signal-to-noise ratio (SNR) of about 45 dB have been obtained.     

Highly parallel collision detection processor for intelligentrobots

A collision detection VLSI processor is proposed in order to achieve ultrahigh-performance processing with an ideal parallel processing scheme. A large number of coordinate transformations and memory accesses to the obstacle memory are fully utilized in the processing algorithm, so that direct collision detection can be executed with a VLSI-oriented regular data flow. The structure of each processing element (PE) is very simple because a PE mainly consists of a COordinate Rotational DIgital Computer (CORDIC) arithmetic unit for the coordinate transformation and memories for the storage of manipulator and obstacle information. When 100 PEs are used for parallel processing, the performance is about 10,000 times faster than that of conventional approaches using a single general-purpose microprocessor     

High-performance dual-gate CMOS utilizing a novel self-alignedpocket implantation (SPI) technology

A self-aligned pocket implantation (SPI) technology is discussed. This technology features a localized pocket implantation using the gate and drain electrodes (TiSi₂ film) as well as self-aligned masks. The gate polysilicon is patterned by KrF excimer laser lithography. The measured minimum gate length L_g (the physical gate length) is 0.21 μm for both N- and P-MOSFETs. A newly developed photoresist was used to achieve less than quarter-micrometer patterns. This process provides high punchthrough resistance and high current driving capability even in such a short channel length. The subthreshold slope of the 0.21-μm gate length is 76 mV/dec for N-MOSFETs and 83 mV/dec for P-MOSFETs. The SPI technology maintains a low impurity concentration in the well (less than 5×10 ¹⁶ cm^-3). The drain junction capacitance is decreased by 36% for N-MOSFETs and by 41% for P-MOSFETs, compared to conventional LDD devices, which results in high-speed circuit operation. The delay time per stage of a 51-stage dual-gate CMOS ring oscillator is 50 ps with a supply voltage of 3.3 V and a gate length of 0.36 μm, and 40 ps with a supply voltage of 2.5 V and a gate length of 0.21 μm     

Photochemical addition reaction of a polymer-bearing pendant vinyl ether with various thiol compounds

Photochemical addition reaction of the pendant vinyl ether group in the polymer ( P-1 ), which was synthesized by the alternate ring-opening copolymerization of glycidyl vinyl ether with phthalic anhydride, with various thiol compounds such as benzenethiol, phenylmethanethiol, 2-mercaptoacetic acid, ethyl 2-mercaptoacetate, N-acetyl-L -cysteine (AcCys), and 1,4-phenylenedi(methylthiol) was carried out using benzophenone (BP) as the photosensitizer in the THF solution. Each reaction proceeded very smoothly to give the corresponding polymers with high conversion, although the degree of reaction of the pendant vinyl ether group in P-1 was affected by the molar ratio between the thiol compounds and the vinyl ether group, and the amounts of photosensitizer BP added. Furthermore, it was also found that optically active polymer containing pendant N-acetyl-L -cysteine residue was synthesized by the photochemical addition reaction of P-1 with AcCys. The reactions of P-1 with dithiol or bisazide compounds occurred effectively to give gel products in the film state, and it was found that the polymer film containing P-1 and those compounds can be applied as negative-type photoresists with high practical photosensitivity. © 1993 John Wiley & Sons, Inc.     

Management of personnel exposure data with a personal computer

This paper describes a software package that manages dosimeter inventory and exposure data with a personal computer. The computer, connected with the access control system, deals with both records of the film badge (FB) supply to workers and the ordering of new FB for a company, processes exposure data and produces reports. The software not only ensures accurate reports but also significantly reduces the tedious labour involved in managing the control system.