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To develop joints using W materials with different thermo-mechanical properties, solid state diffusion bonding involving two different W materials (pure W, K-doped W, or K-doped W-3%Re) and using a pure V interlayer (1.5 mm, 0.5 mm, or 0.05 mm thick) were carried out at 1250 °C for 1 h. The use of a thin interlayer was found to be effective from the point of optimizing the strength and thermal diffusivity. Diffusion bonding at lower temperatures or utilizing W materials with higher recrystallization temperatures were also determined to be effective because pure W can recrystallize at 1250 °C. Further evaluation of a wide range of interlayer thicknesses and thermo-mechanical test conditions is necessary based on the present work to obtain optimum W/V/W joints., source:Shuhei Nogami, Hiroyuki Noto, Michitoshi Toyota, Takaya Hattori, Kohei Otomo, Akira Hasegawa, Solid state diffusion bonding of doped tungsten alloys with different thermo-mechanical properties, Fusion Engineering and Design, Volume 136, Part A, 2018, Pages 76-81, ISSN 0920-3796, https://doi.org/10.1016/j.fusengdes.2017.12.036., source:https://doi.org/10.1016/j.fusengdes.2017.12.036

We developed adaptive optical (AO) two-photon excitation microscopy by introducing a spatial light modulator (SLM) in a commercially available microscopy system. For correcting optical aberrations caused by refractive index (RI) interfaces at a specimen's surface, spatial phase distributions of the incident excitation laser light were calculated using 3D coordination of the RI interface with a 3D ray-tracing method. Based on the calculation, we applied a 2D phase-shift distribution to a SLM and achieved the proper point spread function. AO two-photon microscopy improved the fluorescence image contrast in optical phantom mimicking biological specimens. Furthermore, it enhanced the fluorescence intensity from tubulin-labeling dyes in living multicellular tumor spheroids and allowed successful visualization of dendritic spines in the cortical layer V of living mouse brains in the secondary motor region with a curved surface. The AO approach is useful for observing dynamic physiological activities in deep regions of various living biological specimens with curved surfaces.

We developed two-photon excitation stimulated emission depletion (STED) nanoscopy using high-peak-power sub-nanosecond 655-nm pulses. The STED pulse exhibited ideal optical properties and sufficient pulse energy to realize a 70-nm spatial resolution in the compact setup With electrically controllable components. For biological applications, we screened suitable fluorescent dyes or proteins and realized the sub-100 nm spatial resolution imaging of presynaptic protein clusters in fixed primary cultured neurons Without severe photobleaching. We expect this method to enable visualization of ultrastructures and the cluster dynamics of biomolecules representing physiological functions in living cells and tissue. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Laser scanning microscopy using high-peak-power ultrashort near infrared light pulses can visualize biological microstructures by utilizing non-linear optical processes, such as multi-photon excitation and sum frequency generation. Here we introduced a polarization-resolving detection methodology for a laser scanning microscopy system equipped with a spinning-disk confocal scanner. The developed system achieved high-speed intravital imaging of living tissues with resolving their signals to orthogonally polarized components. First, we applied the system to a liposomal vesicle labeled with the fluorescent lipophilic dye and con firmed the orientation map of the lipid bilayer. Next, by detecting polarization-resolved second harmonic generation signals, the structural orientations of the collagen fibers in fixed mouse tissues were visualized without exogenous or genetic fluorophore labeling. Finally, we demonstrated in vivo polarization-resolved second harmonic generation imaging of the collagen fibers in the mouse skeletal muscles at a 56 Hz temporal resolution. We expect that our developed methodology can achieve real-time visualization, thus, revealing the conformational changes of supramolecular structures in living animals.

Nonmuscle myosin II (NMII) plays an important role in cytokinesis by constricting a contractile ring. However, it is poorly understood how NMII isoforms contribute to cytokinesis in mammalian cells. Here, we investigated the roles of the two major NMII isoforms, NMIIA and NMIIB, in cytokinesis using a WI-38 VA13 cell line (human immortalized fibroblast). In this cell line, NMIIB tended to localize to the contractile ring more than NMIIA. The expression level of NMIIA affected the localization of NMIIB. Most NMIIB accumulated at the cleavage furrow in NMIIA-knockout (KO) cells, and most NMIIA was displaced from this location in exogenous NMIIB-expressing cells, indicating that NMIIB preferentially localizes to the contractile ring. Specific KO of each isoform elicited opposite effects. The rate of furrow ingression was decreased and increased in NMIIA-KO and NMIIB-KO cells, respectively. Meanwhile, the length of NMII-filament stacks in the contractile ring was increased and decreased in NMIIA-KO and NMIIB-KO cells, respectively. Moreover, NMIIA helped to maintain cortical stiffness during cytokinesis. These findings suggest that appropriate ratio of NMIIA and NMIIB in the contractile ring is important for proper cytokinesis in specific cell types. In addition, two-photon excitation spinning-disk confocal microscopy enabled us to image constriction of the contractile ring in live cells in a three-dimensional manner.

We developed a compact stimulated emission depletion (STED) two-photon excitation microscopy that utilized electrically controllable components. Transmissive liquid crystal devices inserted directly in front of the objective lens converted the STED light into an optical vortex while leaving the excitation light unaffected. Light pulses of two different colors, 1.06 and 0.64 mu m, were generated by laser diode-based light sources, and the delay between the two pulses was flexibly controlled so as to maximize the fluorescence suppression ratio. In our experiments, the spatial resolution of this system was up to three times higher than that obtained without STED light irradiation, and we successfully visualize the fine microtubule network structures in fixed mammalian cells without causing significant photo-damage. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement