Torsade de Pointes (TdP) is a lethal arrhythmia that is often drug-induced, thus there is an urgent need for development of models to test or predict the drug sensitivity of human cardiac tissue. ...Here, we present an in vitro TdP model using 3D cardiac tissue sheets (CTSs) that contain a mixture of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes and non-myocytes. We simultaneously monitor the extracellular field potential (EFP) and the contractile movement of the CTSs. Upon treatment with IKr channel blockers, CTSs exhibit tachyarrhythmias with characteristics of TdP, including both a typical polymorphic EFP and meandering spiral wave re-entry. The TdP-like waveform is predominantly observed in CTSs with the cell mixture, indicating that cellular heterogeneity and the multi-layered 3D structure are both essential factors for reproducing TdP-like arrhythmias in vitro. This 3D model could provide the mechanistic detail underlying TdP generation and means for drug discovery and safety tests.
We synthesized the Nd-doped Bi
4
Ge
3
O
12
(BGO) single crystals with different concentrations of Nd (0.1, 0.5, and 1%) by the floating zone method and evaluated the photoluminescence (PL) and ...scintillation properties. In both the PL and scintillation spectra, intrinsic luminescence of BGO was observed at 400–600 nm. In addition, emission peaks due to the 4f–4f transitions of Nd
3+
were observed in the near-infrared range. The 0.5% Nd-doped sample indicated the highest quantum yield of 42.9% among the samples. All the samples showed good linearity between X-ray exposure dose rate and the emission intensity in the NIR range. The lowest detectable dose rates were 0.06 Gy/h in the 0.1 and 1% Nd-doped BGO samples, and that of the 0.5% Nd-doped BGO sample was 0.01 Gy/h.
Tm-doped CaHfO3 crystals were synthesized by the floating zone method equipped four xenon arc lamps, and the photoluminescence (PL), scintillation, and thermally-stimulated luminescence (TSL) ...properties were investigated. The Tm-doped samples exhibited intense sharp emission peaks at around 460 nm due to 4f–4f transitions of Tm3+. The PL and scintillation decay time profiles showed typical decay time constants of 4f–4f transitions of Tm3+. In TSL dose response, the minimum and maximum detection limit of the Tm-doped samples were 10 and 10000 mGy, respectively.
•Undoped and Tm-doped CaHfO3 crystals were synthesized by floating zone method.•Photoluminescence, scintillation, and TSL properties of CaHfO3 crystals were investigated.•Tm-doped CaHfO3 crystals exhibited sharp peaks at around 460 nm.•TSL glow peaks of Tm-doped CaHfO3 crystals appeared at around 90, 140, and 240 °C.
A liquid crystalline polymer (LCP) poly(benzoyl-1,4-phenylene)-co-(1,3-phenylene), nanocomposite was prepared with exfoliated graphene nanoplatelets (GnP) to achieve both high mechanical modulus and ...electrical conductivity. The fabrication technique and the dispersion of nanoplatelets have been shown to be critical to achieve high mechanical modulus at low filler loading. A loading of only 1vol.% of the GnP particles improved the modulus of the LCP nanocomposite by 25% and 55% at a loading of 5vol.%. The electrical conductivity the non-conductive LCP improved to a very high value of 4.5×10−4S/cm with the addition of 5vol.% of GnP nanoparticles.
•The localized steel corrosion of multiple rebars is measured using X-ray technique.•The transverse correlation function among corrosion distributions is estimated.•Spatial steel corrosion is ...simulated using the spectral representation method.•The bending capacity of corroded RC girders is estimated using 3D FE analysis.•The effect of the transverse correlation of steel corrosion is investigated.
The deterioration of reinforced concrete (RC) structures due to chloride-induced corrosion is not spatially uniform because of the spatial variability related to material properties and environmental stressors. This variation has a substantial effect on the reliability of RC structures. However, few experimental studies have focused on the effect of the interaction of corrosion pits among tensile rebars on the reliability of RC structures. Therefore, in this paper, an experimental procedure that incorporates X-ray and digital image processing techniques was conducted on RC slab specimens subjected to accelerated corrosion. Using the experimental results, the parameter of the transverse correlation function of steel weight loss distributions was estimated to investigate how the corrosion pits in corroded rebars are correlated. Based on the experimentally obtained model parameters, the spatial steel weight loss distributions were simulated by spectral representation method. A three-dimensional (3D) nonlinear finite element (FE) analysis of RC structures with simulated steel weight loss distributions was conducted to obtain the ultimate bending capacity of RC structures. In an illustrative example, the effect of the transverse correlation among steel weight loss distributions of multiple tensile rebars on the failure probability of RC girders was quantified.
We synthesized the 0.1, 0.5, 1.0, and 1.5% Ce-doped mullite single crystals by the floating zone method and evaluated their photoluminescence (PL) and thermally stimulated luminescence (TSL) ...properties. The single-phase orthorhombic structure was confirmed in all the samples from powder X-ray diffraction patterns. The transmittance spectra of all the samples showed the absorption related to the 4f-5d transitions of Ce3+ ions and optical band gap of mullite. The Ce-doped mullite single crystals had the PL attributed to the 5d-4f transitions of Ce3+ ions. In TSL properties, TSL glow curves had the glow peaks at 250 and 370 °C, and TSL spectra heated at 250 and 370 °C had the peak at around 390 nm owing to the Ce3+ ions. TSL dose response functions showed linear response from 0.01 mGy to 10 Gy for the 1.0% Ce-doped mullite single crystal and from 0.1 mGy to 10 Gy for the 0.1, 0.5, and 1.5% Ce-doped ones. The 1.0% Ce-doped mullite single crystal could be used multiple times for dosimetry. In addition, the TSL intensity of the 1.0% Ce-doped mullite single crystal after 7 days from X-ray irradiation was about 82.4% from immediately one after X-ray irradiation.
•We have synthesized Ce-doped Al4SiO8 single crystals by floating zone method.•We have characterized the photoluminescence, and thermally stimulated luminescence.•All the samples showed luminescence properties due to the 5d-4f transitions of Ce3+.•The lower detection limit of the 1.0% Ce-doped Al4SiO8 single crystals was better than those of a part of commercial dosimeters.
This paper presents the results of photoluminescence and X-ray induced scintillation properties of xCe:33.3BaO-66.6SiO2 (x = 0, 0.05, 0.1, 0.5, 1.0, 2.0) glasses produced by the Floating Zone (FZ) ...method. We observed intense emission from 5d–4f transition of Ce3+ and the concentration quenching with the increase of Ce concentration in photoluminescence (PL) and scintillation properties. The lowest Ce-doped sample indicated the highest scintillation intensity in the X-ray induced scintillation measurement. The non-doped sample had the highest afterglow level, and the afterglow levels decreased with Ce addition amount. From these results, it was found to be in a trade-off relationship between the scintillation intensity the and afterglow characteristics in present samples.
•Succeeded in making Ce-doped BaO–SiO2 glass using Floating Zone furnace.•The lowest Ce-doped glass shown the highest scintillation intensity among our samples.•We found that it is effective to introduce more Ce to reduce afterglow levels in this glass compositions.
Tellurite glass (TeG) and its glass-ceramics (TeGC435 and TeGC455), with a composition of 10Eu2O3–10BaO–80TeO2, were prepared and their luminescence properties were evaluated. TeG was prepared via ...the melt quenching technique, while TeGC435 and TeGC455 were fabricated by heat treating TeG at 435 and 455 °C, respectively, for 5 h each. The Eu2Te6O15 crystal phase was formed in TeGC435 and TeGC455. Both the glass and glass-ceramics showed sharp photoluminescence and scintillation peaks, attributed to the 4f→4f transitions of Eu3+. The highest quantum yield was obtained for TeG, whereas the highest integrated scintillation intensity was obtained for TeGC455. The scintillation intensity of TeGC455 was approximately 10% of that of the Bi4Ge3O12 single crystal. Furthermore, typical decay times derived from the 4f→4f transitions were obtained for TeG, TeGC435, and TeGC455 during photoluminescence and scintillation.
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