GaN‐based high‐output‐power blue laser diodes for display applications

Abstract— We succeeded in fabricating high‐output‐power blue (445 nm) laser diodes (LDs) with an output power of 500 mW. The operating current, voltage, and wall‐plug efficiency of these LDs were 480 mA, 4.8 V, and 21.7%, respectively. The lifetime of these LDs was estimated to be 10,000 hours under continuous‐wave operation at 25°C. From examination of the degradation mode, we found that the operating current seriously affects the lifetime of LDs. In the next stage, we will focuse on the optimization and sophistication of the manufacturing processes to fabricate longer‐lifetime (>30,000 hours) blue LDs.     

Fluoroscopic bone fragment tracking for surgical navigation in femur fracture reduction by incorporating optical tracking of hip joint rotation center

A new method for fluoroscopic tracking of a proximal bone fragment in femoral fracture reduction is presented. The proposed method combines 2-D and 3-D image registration from single-view fluoroscopy with tracking of the head center position of the proximal femoral fragment to improve the accuracy of fluoroscopic registration without the need for repeated manual adjustment of the C-arm as required in stereo-view registrations. Kinematic knowledge of the hip joint, which has a positional correspondence with the femoral head center and the pelvis acetabular center, allows the position of the femoral fragment to be determined from pelvis tracking. The stability of the proposed method with respect to fluoroscopic image noise and the desired continuity of the fracture reduction operation is demonstrated, and the accuracy of tracking is shown to be superior to that achievable by single-view image registration, particularly in depth translation.     

Conductive polymer patterned media fabricated by diblock copolymer lithography for scanning multiprobe data storage

A conductive polymer dot pattern has been fabricated as a patterned medium using diblock copolymer lithography (DCL) for scanning multiprobe data storage systems (SMDSSs). DCL can easily provide a higher dots pattern density than that obtained using electron beam lithography. For DCL, the microphase-separated structure of polystyrene-block-polymethylmethacrylate is utilized. Then, the closed dot pattern of polyaniline (PANI) with a center to center distance of adjacent dots of 30?nm is fabricated by DCL. Electrical modification experiments of the fabricated PANI dots are demonstrated using scanning probe microscopy (SPM). As a result, the conductivities of the modified dots are selectively changed by applying modification voltages with the tip of the SPM probe. Recording on the conductive polymer with 30?nm pitch at the minimum can be demonstrated, which corresponds to a recording density of ～700?Gbits?inch(-2). These results show that the conductive polymer patterned medium has the potential ability to achieve high-density recording for SMDSSs.     

Micromachined Si cantilever arrays for parallel AFM operation

Silicon cantilever arrays with a very small pitch for parallel AFM operations were studied. We fabricated 1x104 in eight groups and 1x30 Si probe arrays and produced a smaller pitch (15 μm) between probe tips by using Si anisotropic etching with a vertical wall shaped oxide mask. The vertical controls of Si probes were able to operate individually or in a group by integrating electrostatic actuators into the cantilevers of the probes. The fabricated Si cantilever arrays showed reasonable dynamic characteristics for the probe cantilever and reliable parallel operation of AFM.     

Crack propagation behavior of cermets and cemented carbides under repeated thermal shocks by the improved quench test

In this study, an improved quench testing method for thermal shock resistance has been proposed. Repeated thermal shock tests were performed on cemented carbides to show the advantages of the new proposed method that would enable us to estimate an intrinsic relationship between the crack propagation rate and the stress intensity factor under repeated thermal shocks. The cyclic thermal fatigue crack propagation behavior and fracture toughness values were shown to be independent of the specimen heights and the cooling media employed. We then evaluated the thermal crack propagation behavior for cermets and cemented carbides by using this method, and discussed the differences between both materials in the crack growth behavior on the basis of their microstructures.     

Distinct characters of Clostridium botulinum type A strains and their toxin associated with infant botulism in Japan

Four strains of Clostridium botulinum type A having been associated with infant botulism in Japan, and another strain isolated from honey not associated with infant botulism, were found to be hemagglutinin (HA) negative. These strains do not produce L (Mr 500 kDa) nor LL toxin (Mr 900 kDa) but M toxin (Mr 300 kDa) only. No marked difference was found between the HA-positive and HA-negative strains in other biochemical properties, but the HA-negative strains tended to colonize more easily in the intestines of infant mice than did HA-positive strains. The toxin of HA-positive strains and that of HA-negative strains differed in the antigenicity of part of the toxic component and that of the nontoxic component, and in the molecular size of the toxic component.