Elastic properties of human cortical and trabecular lamellar bone measured by nanoindentation

An experimental investigation was undertaken to measure the intrinsic elastic properties of several of the microstructural components of human vertebral trabecular bone and tibial cortical bone by the nanoindentation method. Specimens from two thoracic vertebrae (T-12) and two tibiae were obtained from frozen, unembalmed human male cadavers aged 57 and 61 years. After drying and mounting in epoxy resin nanoindentation tests were conducted to measure Young's modulus and the hardness of individual trabeculae in the vertebrae and single osteons, and interstitial lamellae in the tibiae. Measurements on the vertebral trabeculae were made in the transverse direction, and the average Young's modulus was found to be 13.5 +/- 2.0 GPa. The tibial specimens were tested in the longitudinal direction, yielding moduli of 22.5 +/- 1.3 GPa for the osteons and 25.8 +/- 0.7 GPa for the interstitial lamellae. Analysis of variance showed that the differences in the measured moduli are statistically significant. Hardness differences among the various microstructural components were also observed.     

Effects of Nafion impregnation on performances of PEMFC electrodes

The effect of Nafion loading on the electrode polarization characteristics of a conventional proton exchange membrane (PEM) fuel cell electrode has been investigated in terms of both H₂/O₂ and H₂/air performance. Correlation of Nafion loading with the activation polarization characteristics shows an initial increase of activity upto a loading of 1.3 mg/cm² followed by a more gradual change with maxima at 1.9 mg/cm² for both oxygen and air. This trend correlated well with the decrease in charge transfer resistance and increase in the electrochemically active surface area. The contributions to the linear ohmic polarization region of both the H₂/O₂ and H₂/air performance are predominantly from ionic resistance as well as diffusional contributions in the catalyst layer. Among all the polarization losses those due to mass transport were the highest. Fits using a thin film agglomerate model showed a rapid increase in the film thickness with Nafion loading in the pores of the carbon of the catalyst layer followed by an equilibrium of 800 Å thickness at a Nafion loading of 1.9 mg/cm². Further additions caused deeper penetration of this Nafion film into the catalyst layer increasing the diffusional pathways for the reactant gases. These results correlate well with the mass transport characteristics in O₂ and air as well as morphological characterization of the electrode based on SEM and pore volume distributions.     

PCB-compatible optical interconnection using 45/spl deg/-ended connection rods and via-holed waveguides

In this paper, a new architecture for a chip-to-chip optical interconnection system is demonstrated that can be applied in a waveguide-embedded optical printed circuit board (PCB). The experiment used 45/spl deg/-ended optical connection rods as a medium to guide light paths perpendicularly between vertical-cavity surface-emitting lasers (VCSELs), or photodiodes (PDs) and a waveguide. A polymer film of multimode waveguides with cores of 100/spl times/65 /spl mu/m was sandwiched between conventional PCBs. Via holes were made with a diameter of about 140 /spl mu/m by CO/sub 2/-laser drilling through the PCB and the waveguide. Optical connection rods were made of a multimode silica fiber ribbon segment with a core diameter of 62.5 and 100 /spl mu/m. One end of the fiber segment was cut 45/spl deg/ and the other end 90/spl deg/ by a mechanical polishing method. These fiber rods were inserted into the via holes formed in the PCB, adjusting the insertion depth to locate the 45/spl deg/ end of rods near the waveguide cores. From this interconnection system, a total coupling efficiency of about -8 dB was achieved between VCSELs and PDs through connection rods and a 2.5 Gb/s /spl times/ 12-ch data link demonstrated through waveguides with a channel pitch of 250 /spl mu/m in the optical PCB.     

Whole Exome Sequencing for a Patient with Rubinstein-Taybi Syndrome Reveals de Novo Variants besides an Overt CREBBP Mutation

Rubinstein-Taybi syndrome (RSTS) is a rare condition with a prevalence of 1 in 125,000–720,000 births and characterized by clinical features that include facial, dental, and limb dysmorphology and growth retardation. Most cases of RSTS occur sporadically and are caused by de novo mutations. Cytogenetic or molecular abnormalities are detected in only 55% of RSTS cases. Previous genetic studies have yielded inconsistent results due to the variety of methods used for genetic analysis. The purpose of this study was to use whole exome sequencing (WES) to evaluate the genetic causes of RSTS in a young girl presenting with an Autism phenotype. We used the Autism diagnostic observation schedule (ADOS) and Autism diagnostic interview revised (ADI-R) to confirm her diagnosis of Autism. In addition, various questionnaires were used to evaluate other psychiatric features. We used WES to analyze the DNA sequences of the patient and her parents and to search for de novo variants. The patient showed all the typical features of Autism, WES revealed a de novo frameshift mutation in CREBBP and de novo sequence variants in TNC and IGFALS genes. Mutations in the CREBBP gene have been extensively reported in RSTS patients, while potential missense mutations in TNC and IGFALS genes have not previously been associated with RSTS. The TNC and IGFALS genes are involved in central nervous system development and growth. It is possible for patients with RSTS to have additional de novo variants that could account for previously unexplained phenotypes.     

Bendable and Splitter-Integrated Optical Subassembly Based on a Flexible Optical Board

A bendable and splitter-integrated optical subassembly (OSA) is suggested as a short-distance board-to-board optical interconnection. This OSA was fabricated by simply packaging a vertical-cavity surface-emitting laser on a flexible optical board having an embedded 1 $times$ 8 optical splitter waveguide. Finally, we measured various optical characteristics of the OSA, including insertion, twist, and bending losses.      

High-flexibility piezoelectric ribbon fiber fabrication through multi-material thermal drawing

In this study, an amorphous poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) copolymer with a high yield strain (approximately 18 %) is proposed as a cladding material for highly flexible and reliable piezoelectric ribbon fibers. Macro preforms are fabricated for thermal drawing (TD) processes, in which a poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) film is sandwiched between two electrically conductive composite sheets (carbon black (CB)/polypropylene (PP)). The piezoelectric device is cladded with the P(VDF-HFP) copolymer. The preform geometries and TD parameters are optimized to overcome the incompatibility of flow characteristics among P(VDF-HFP), P(VDF-TrFE), and CB/PP composite at the drawing temperature, yielding fibers of length more than 80 m through TD. After annealing and poling, the fiber produces approximately 5 V (peak-to-peak) under 2.5 % tensile strain and 0.5 V (peak-to-peak) under bending deformation, with a 5-mm radius of curvature. Furthermore, the piezoelectric fiber shows no severe degradation in the output voltage after 10000 cycles of bending deformation with 1-mm radius of curvature. The piezoelectric ribbon fiber developed herein has potential as a flexible tensile, pressure, or bending sensor fiber for wearable applications.

     

Effect of Ta addition on magnetic properties of (Fe45Pt55)1−x-Tax thin films

It was studied that FePt-Ta thin films prepared on MgO (1 0 0) buffer-layer by DC/RF magnetron co-sputtering have shown better magnetic properties and micro structural improvement. The Ta-doped FePt-Ta films indicate somewhat differences in micro structural ordering and the aspect of grain growth after annealing. With respect to magnetic property, the sample having 30% increased coercivity was obtained after a heat treatment at 700 °C. In particular the addition of Ta (5.5%) enhances the L1₀ ordering of FePt at relatively high temperature (above 500 °C).     

A moving-actuator type electromechanical total artificial heart.II. Circular type and animal experiment

A new type of electromechanical total artificial heart (TAH) based on circular rolling-cylinder mechanism was developed to overcome critical problems in motor-driven artificial hearts such as large size and difficulties in fitting the heart to atrial remnants and arterial vessels. Its performance and reliability were evaluated in mock circulation and in an animal implant experiment. The total weight and volume of the pump is 650 g and 600 mL, respectively. This new pump was implanted in a calf for total heart replacement and 96 h of survival was achieved. The whole system, including pump, controller, and control algorithm performed well enough to improve the prospect of eventual clinical application of our TAH system.     

Optical backplane system using waveguide-embedded PCBs and optical slots

As discussed in this paper, a practical optical backplane system was demonstrated, using a waveguide-embedded optical backplane board, processing boards, and optical slots for board-to-board interconnection. A metal optical bench was used as a packaging die for the optical devices and the integrated circuit chips in both the transmitter and the receiver processing boards. The polymer waveguide was produced by means of a hot-embossing technique and was then embedded following a conventional lamination processes. The average propagation loss of these waveguides was approximately 0.1 dB/cm at 850 nm. The dimension and optical properties of the waveguide in an optical backplane board were unchanged after lamination. As connection components between transmitter/receiver processing boards and an optical backplane board, optical slots were used for easy and repeatable insertion and extraction of the boards with a micrometer-scale precision. A 1/spl times/4 850-nm vertical-cavity surface-emitting laser array was used with 2 dBm of output power for the transmitter and a p-i-n photodiode array for the receiver. This paper successfully demonstrates 8 Gb/s of data transmission between the transmitter processing board and the optical backplane board.