Improvement of Biocompatibility of Silicone Elastomer by Surface Modification

γ-Methacryloxypropyltrimethoxysilane (γ-MPS) was grafted to silicone due to emulsion polymerization to induce Si-OH groups, in order to provide silicone with bioactivity spontaneous deposition of apatite in body fluid and to improve cytocompatibility. Apatite deposited on the grafted silicone within 7 days of soaking in 1.5 times as concentrated as the Kokubo solution. Osteoblastic cells (MC3T3-E1) were cultured on the specimens up to 7 days. After 5 days of culture, the number of MC3T3-E1 cells on the grafted specimen was much greater than that on the original specimen. These results indicated that the biocompatibility of silicone elastomer was improved by the grafting γ-MPS

Orbital- and spin-phase variability in the X-ray emission from the accreting pulsar Cen X-3

We analyzed 39 ks NuSTAR observation data of the high mass X-ray binary Cen X-3 in order to investigate the orbital- and spin-phase spectral variability. The observation covers the orbital phase of $\Phi=0.199$-$0.414$ of the source, where $\Phi=0$ corresponds to the mid-eclipse. The orbital-phase-resolved spectroscopy revealed that low energy photons are more dominant for the spectral fluctuation, and a large part of the variability can be explained in terms of absorption by clumps of stellar wind. The spin-phase-resolved spectroscopy together with energy-resolved pulse profiles, on the other hand, presented large flux variations in high energy bands, which suggests that the origin of the variability is the different efficiency of Comptonization inside the accretion column. The energy band which includes Fe emission lines or cyclotron resonance scattering feature (CRSF) shows distinct variability compared to the nearby bands. The Fe lines show low variability along the spin phase, which indicates that the emission regions are apart from the neutron star. The central energy and strength of the CRSF are both positively correlated with the spin-phase-resolved flux, which suggests that the emitted photons face stronger magnetic fields and deeper absorption when they come from high-flux regions. We also examined the independence of the orbital- and spin-phase variability. They showed no correlation with each other and were highly independent, which implies the accretion stream is stable during the observation.Comment: 20 pages, 12 figures, accepted for publication in Ap

Development of catheter-type tactile sensor composed of polyvinylidene fluoride (PVDF) film

To achieve quantitative palpation in vivo, we developed a catheter-type tactile sensor composed of a polyvinylidene fluoride film for minimally invasive surgery. We evaluated the fundamental performance of the prototype sensor by a weight-drop test. We also measured the output of the prototype sensor as it was inserted into a blood vessel model with shapes mimicking lesions. The ø2-mm sensor passed easily into the blood vessel model with lesion-like shapes. Sensor outputs corresponded to the shape of the inner wall of the blood vessel model, making it possible to determine the position of a protrusion and the convexity interval of a rough surface by filtering and frequency analysis of the output

Mice with defects in HB-EGF ectodomain shedding show severe developmental abnormalities

Heparin-binding EGF-like growth factor (HB-EGF) is first synthesized as a membrane-anchored form (proHB-EGF), and its soluble form (sHB-EGF) is released by ectodomain shedding from proHB-EGF. To examine the significance of proHB-EGF processing in vivo, we generated mutant mice by targeted gene replacement, expressing either an uncleavable form (HBuc) or a transmembrane domain–truncated form (HBΔtm) of the molecule. HBuc/uc mice developed severe heart failure and enlarged heart valves, phenotypes similar to those in proHB-EGF null mice. On the other hand, mice carrying HBΔtm exhibited severe hyperplasia in both skin and heart. These results indicate that ectodomain shedding of proHB-EGF is essential for HB-EGF function in vivo, and that this process requires strict control