Tensile Strength of Unidirectional Carbon Fiber-Reinforced Plastic Composites

The tensile strengths of unidirectionally aligned carbon fiber-reinforced plastic (UD-CFRP) were predicted by implementing a spring element model (SEM) that takes into account a stress concentration acting on an intact fiber surface originated from a fracture site in an neighboring fiber. The surface stress concentration was experimentally investigated by implementing multi-fiber fragmentation testing in combination with the SEM simulation. Four types of epoxy materials were selected to explore the effects of matrix polymer properties on the surface stress concentration. The size scaling results, coupled with the results of the SEM simulation, designed to take into account the surface stress concentration, were reasonably consistent with the experimentally obtained data on the tensile strengths of the UD-CFRP composites, irrespective of the differences in the matrix mechanical characteristics. The possible mechanisms by which additional stress concentration is generated on an intact fiber surface were analyzed numerically using the finite element method

Hydrodynamics of Francis turbine operation at deep part load condition

The electrical energy production from New and Renewable Energy (NRE) sources have become increasingly important in the past decades. However, intermittent electrical generation from NRE sources due to their stochastic nature often prevents stable power output from existing power grids. To enable a smooth integration of NRE sources, flexible operations at hydraulic power plants are key to providing the capability of primary and secondary grid control to balance the energy production. The rapid growth of the NRE sources nonetheless requires hydraulic machines to function in an extended operating range, especially down to extremely low discharge conditions called deep part load operation. Such off-design conditions provoke various types of cavitation flows, posing a threat to stable operations at hydraulic units. Inter-blade cavitation vortices are a typical example of cavitation phenomena observed at deep part load operation. However, its dynamic characteristics are insufficiently understood today. The main objective of the present research is to unveil the flow characteristics at deep part load conditions and the physical mechanisms responsible for the inter-blade vortex development. The experimental is carried out with a physical reduced scale model of a Francis turbine. The characteristics of the flow in the draft tube is first investigated by wall pressure fluctuation and velocity surveys by PIV (Particle Image Velocimetry) measurements. For investigations of inter-blade cavitation vortices, the present study introduces a novel visualization technique using an instrumented guide vane, providing unprecedented images of cavitation development inside the runner blade channel. The binary image processing technique enables the successful evaluation of inter-blade cavitation vortices in the images. The analyses demonstrate that the probability of the inter-blade cavitation development is significantly high close to the runner hub. Furthermore, the mean vortex line is calculated. Additionally, the impact of the inter-blade vortex on the pressure field is investigated by on-board instrumentation on the runner blade. It reveals that the presence of an inter-blade vortex induces stochastic pressure oscillations on the blade. Moreover, the survey of the wall pressure difference between pressure and suction sides of the blade suggests the development of a backflow region near the hub, which is closely related to inter-blade vortex development. In an effort to better understand the flow structure in the draft tube and inside the blade channel, numerical simulations by an unsteady RANS approach are performed. Flow analysis in the draft tube and the simulated inter-blade vortices are in good agreement with the experimental results. Furthermore, the simulated flow inside the blade channel confirms the development of a backflow region on the hub near the runner outlet. The skin-friction analyses evidence that the backflow region as well as inter-blade vortex development are provoked by flow separation on the hub, which is caused by the misaligned flow condition inside the blade channel. The investigations are furthermore extended to identify the influence of inter-blade vortices on the specific energy dissipation in the runner. The quantitative evolution of the specific energy loss using the specific rothalpy reveals that inter-blade vortices cause the energy loss through the blade channel

A theoretical approach to thermal noise caused by an inhomogeneously distributed loss -- Physical insight by the advanced modal expansion

We modified the modal expansion, which is the traditional method used to calculate thermal noise. This advanced modal expansion provides physical insight about the discrepancy between the actual thermal noise caused by inhomogeneously distributed loss and the traditional modal expansion. This discrepancy comes from correlations between the thermal fluctuations of the resonant modes. The thermal noise spectra estimated by the advanced modal expansion are consistent with the results of measurements of thermal fluctuations caused by inhomogeneous losses.Comment: 10 pages, 4 figure

APC/C–Cdc20-mediated degradation of cyclin B participates in CSF arrest in unfertilized Xenopus eggs

AbstractIn vertebrates, unfertilized eggs are arrested at meiotic metaphase II (meta-II) by cytostatic factor (CSF), with Cdc2 activity maintained at a constant, high level. CSF is thought to suppress cyclin B degradation through the inhibition of the anaphase-promoting complex/cyclosome (APC/C)-Cdc20 while cyclin B synthesis continues in unfertilized eggs. Thus, it is a mystery how Cdc2 activity is kept constant during CSF arrest. Here, we show that the APC/C–Cdc20 can mediate cyclin B degradation in CSF-arrested Xenopus eggs and extracts, in such a way that when Cdc2 activity is elevated beyond a critical level, APC/C–Cdc20-dependent cyclin B degradation is activated and Cdc2 activity consequently declines to the critical level. This feedback control of Cdc2 activity is shown to be required for keeping Cdc2 activity constant during meta-II arrest. We have also shown that Mos/MAPK pathway is essential for preventing the cyclin B degradation from inactivating Cdc2 below the critical level required to sustain meta-II arrest. Our results indicate that under CSF arrest, Mos/MAPK activity suppresses cyclin B degradation, preventing Cdc2 activity from falling below normal meta-II levels, whereas activation of APC/C–Cdc20-mediated cyclin B degradation at elevated levels of Cdc2 activity prevents Cdc2 activity from reaching excessively high levels

Polymyositis and myocarditis after chemotherapy for advanced thymoma

AbstractPolymyositis and myocarditis very rarely develop during chemotherapy for thymoma. Most reported cases of myocarditis and polymyositis associated with thymoma were found at autopsy of patients who died of acute progression of myocarditis. We describe our experience with a 64-year-old man who had recurrent thymoma accompanied by polymyositis and myocarditis. Lower-extremity myalgia and palpitations developed on day 25 of chemotherapy with weekly paclitaxel. Steroid pulse therapy was effective for the management of polymyositis and myocarditis associated with thymoma. Polymyositis and myocarditis after paclitaxel monotherapy have not been documented previously. Whether paclitaxel induced polymyositis and myocarditis is unclear and these symptoms might have been a paraneoplastic phenomenon associated with thymoma. However, our experience suggested that patients with thymoma who received paclitaxel-based chemotherapy should be carefully observed for polymyositis and myocarditis. If such patients have high serum creatine phosphokinase and troponin levels, steroid pulse therapy should be considered without delay

Dental pulp stem cell factors for treating RISR

Radiation-induced skin ulceration is a frequent complication of radiotherapy for cancer treatment. Stem cells from human exfoliated deciduous teeth (SHEDs) can regenerate various tissues. In this study, we investigated the impact of SHED-conditioned media (SHED-CM) on radiation-induced ulceration. Mouse necks were locally irradiated with a single dose of 15 Gy of radiation. A week after the irradiation, most of the wild-type mice generated ulcer surrounded by severe erythema. Intra-venous administration of SHED-CM effectively inhibited the ulcer formation. Histological examination revealed that SHED-CM treatment inhibited radiation-induced dermal thickness and epithelial hyperplasia. SHED-CM could be a useful treatment option for radiation-induced skin ulceration

Effect of carbon surface on degradation of supercapacitors in a negative potential range

The stability of supercapacitors is the key factor for their use under high temperature, high voltage and long-term durability. To improve the supercapacitor stability, there is a need to understand the degradation mechanism. In this work, the degradation sites in a carbon electrode at negative potential range are investigated in two common organic electrolytes: 1 M Et4NBF4 dissolved in propylene carbonate and in acetonitrile. To elucidate the common factor over a wide range of carbon materials, we examined eight kinds of carbon materials including activated carbons, carbon blacks, zeolite-template carbon (high surface area and a large amount of carbon edge sites) and graphene mesosponge (high surface area and a little amount of carbon edge sites). Their surface structures are distinguished into two regions: carbon basal planes and edge sites by nitrogen physisorption and high-sensitivity temperature-programmed desorption up to 1800 °C. Unlike the degradation at positive potential range, initial degradation reactions at negative potential range occur mainly on the carbon basal planes rather than the edge sites. This finding is corroborated by the theoretical calculation.This work was supported by JSPS KAKENHI (grant Nos. 17H01042 and 19H00913); the Dynamic Alliance for Open Innovation Bridging Human, Environment, and Materials program; and the Network Joint Research Centre for Materials and Devices. R. T. acknowledges the China Scholarship Council for the financial support. MINECO and FEDER (CTQ2015-66080-R MINECO/FEDER) are acknowledged for financial support

Case Reports of TFE3-Rearranged Renal Cell Carcinoma: FDG-PET Uptake Might Help Diagnosis

Translocation and transcription factor E3 (TFE3)-rearranged renal cell carcinoma (RCC) is a rare subtype of RCCs characterised by the fusion of the TFE3 transcription factor genes on chromosome Xp11.2 with one of the multiple genes. TFE3-rearranged RCC occurs mainly in children and adolescents, although middle-aged cases are also observed. As computed tomography (CT)/magnetic resonance imaging (MRI) findings of TFE3-rearranged RCC overlap with those of other RCCs, differential diagnosis is often challenging. In the present case reports, we highlighted the features of the fluorine-18-labelled fluorodeoxyglucose positron emission tomography with CT (FDG PET-CT) in TFE3-rearranged RCCs. Due to the rarity of the disease, FDG PET-CT features of TFE3-rearranged RCC have not yet been reported. In our cases, FDG PET-CT showed high standardised uptake values (SUVmax) of 7.14 and 6.25 for primary tumours. This might imply that TFE3-rearranged RCC has high malignant potential. This is conceivable when the molecular background of the disease is considered in terms of glucose metabolism. Our cases suggest that a high SUVmax of the primary tumour is a clinical characteristic of TFE3-rearranged RCCs

Hydro-acoustic resonance behavior in presence of a precessing vortex rope: observation of a lock-in phenomenon at part load Francis turbine operation

Francis turbines operating at part load condition experience the development of a cavitating helical vortex rope in the draft tube cone at the runner outlet. The precession movement of this vortex rope induces local convective pressure fluctuations and a synchronous pressure pulsation acting as a forced excitation for the hydraulic system, propagating in the entire system. In the draft tube, synchronous pressure fluctuations with a frequency different to the precession frequency may also be observed in presence of cavitation. In the case of a matching between the precession frequency and the synchronous surge frequency, hydro-acoustic resonance occurs in the draft tube inducing high pressure fluctuations throughout the entire hydraulic system, causing torque and power pulsations. The risk of such resonances limits the possible extension of the Francis turbine operating range. A more precise knowledge of the phenomenon occurring at such resonance conditions and prediction capabilities of the induced pressure pulsations needs therefore to be developed. This paper proposes a detailed study of the occurrence of hydro-acoustic resonance for one particular part load operating point featuring a well-developed precessing vortex rope and corresponding to 64% of the BEP. It focuses particularly on the evolution of the local interaction between the pressure fluctuations at the precession frequency and the synchronous surge mode passing through the resonance condition. For this purpose, an experimental investigation is performed on a reduced scale model of a Francis turbine, including pressure fluctuation measurements in the draft tube and in the upstream piping system. Changing the pressure level in the draft tube, resonance occurrences are highlighted for different Froude numbers. The evolution of the hydro-acoustic response of the system suggests that a lock-in effect between the excitation frequency and the natural frequency may occur at low Froude number, inducing a hydro-acoustic resonance in a random range of cavitation numbers