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Two-phase pressure drop in the debris has been studied by many researchers concerning the debris cooling characteristics during a severe accident in a nuclear reactor. However, its flow regime transition of the two-phase flow in the debris has not been well understood, which strongly affects the interfacial drag and the pressure drop. Conventional models for gas-liquid two-phase flow pressure drop have not been established to evaluate interfacial drag accurately. In this study, high-speed imaging of a two-dimensional network model was performed to clarify the effect of flow patterns on interfacial drag and pressure drop. Usually, it would not be easy to visualize such two-phase flow behavior in a randomly packed bed due to the reflection/refraction of light and/or overlapping bubbles, even if the test section is made of transparent materials. Therefore, in this study, a test section, which simulates a two-dimensional network of porous structures, was fabricated to avoid overlapping bubbles. The two-phase flow pattern in the porous structure has been identified by high-speed imaging of the two-dimensional network model. The flow regime map based on the flow pattern visualization results is applied to the pressure drop evaluation and it could reduce the overestimation of experimental values. The experimental results suggested that the interfacial drag term should be modified in the gas-liquid two-phase flow pressure drop model.

type:Text, Plastic bronchitis (PB) is a severe acute respiratory disease that develops as a result of the formation of branching mucus plugs in the bronchial tree. PB is known as a complication of influenza A virus infection, but some cases have been associated with influenza B virus infections. This patient was a 3-year-old boy with no history of allergic disease who developed PB requiring ventilator management after influenza B virus infection. He was hospitalized and managed with ventilator support because of acute respiratory failure. Influenza B virus infection was diagnosed via rapid antigen test and real-time reverse-transcription polymerase chain reaction (RT-PCR). A bronchoscopy performed after a chest X-ray and computed tomography confirmed the presence of extensive atelectasis in the right lung field and mucus plugs in the right bronchus. The patient's respiratory condition improved rapidly after removal of the plugs. Quantitative real-time RT-PCR performed with nasal and aspirated sputum samples obtained at hospitalization revealed a higher viral RNA load in the upper rather than in the lower respiratory tract. Viral replication in the lower respiratory was not found to be a major contributor toward mucus plug formation. The finding of increased serum IgE in the absence of a history of allergic disease suggests that an allergic reaction contributed to the formation of mucus plugs.

In neutron transmission spectroscopic imaging, the transmission spectrum of each pixel on a two-dimensional detector is analyzed and the real-space distribution of microscopic information in an object is visualized with a wide field of view by mapping the obtained parameters. In the analysis of the transmission spectrum, since the spectrum can be classified with certain characteristics, it is possible for machine learning methods to be applied. In this study, we selected the subject of solid-liquid phase fraction imaging as the simplest application of the machine learning method. Firstly, liquid and solid transmission spectra have characteristic shapes, so spectrum classification according to their fraction can be carried out. Unsupervised and supervised machine learning analysis methods were tested and evaluated with simulated datasets of solid-liquid spectrum combinations. Then, the established methods were used to perform an analysis with actual measured spectrum datasets. As a result, the solid-liquid interface zone was specified from the solid-liquid phase fraction imaging using machine learning analysis.

In neutron transmission spectroscopic imaging, the transmission spectrum of each pixel on a two-dimensional detector is analyzed and the real-space distribution of microscopic information in an object is visualized with a wide field of view by mapping the obtained parameters. In the analysis of the transmission spectrum, since the spectrum can be classified with certain characteristics, it is possible for machine learning methods to be applied. In this study, we selected the subject of solid-liquid phase fraction imaging as the simplest application of the machine learning method. Firstly, liquid and solid transmission spectra have characteristic shapes, so spectrum classification according to their fraction can be carried out. Unsupervised and supervised machine learning analysis methods were tested and evaluated with simulated datasets of solid-liquid spectrum combinations. Then, the established methods were used to perform an analysis with actual measured spectrum datasets. As a result, the solid-liquid interface zone was specified from the solid-liquid phase fraction imaging using machine learning analysis.

Pulsed neutron transmission spectroscopy was applied to clarify a phase change phenomena of lead-bismuth eutectics (LBE). The melting and solidification behaviors of the LBE should be well understood to enhance the safety of an LBE-cooled accelerator driven system. In this study, the heating experiments were performed using a rectangular test section and LBE phase change process was visualized by the energy-resolved pulsed neutron imaging at BL22 RADEN facility in J-PARC and the solid/liquid interface was identified from the radiograph and Bragg edge information. The transient location of the interface was compared with measured temperature profiles and it would be useful to evaluate the LBE thermal properties.

We have synthesized metal oxide nanoparticles through hydrothermal reaction at around 400 °C and 25 MPa by mixing the stream of metal ion solution at room temperature with another stream of supercritical water in a continuous flow-type reactor. In order to visualize the mixing behavior of the two streams, we performed neutron tomography measurements. By performing tomography measurements while rotating the mixing piece with supplying supercritical water and room temperature water, we succeeded in obtaining the three dimensional distribution of neutron attenuation. The results clearly showed how the two streams mix, which serves as a reference for numerical simulation.

Gas-liquid two-phase flow in a narrow gap has been studied to develop a solid target cooling system for an accelerator driven system. Flow measurements are important to understand two-phase flow dynamics also in such a narrow channel. Although contact methods can measure detailed structure of two-phase flow, the intrusive effect on the flow becomes relatively larger in such a small channel. Therefore, non-intrusive measurement would be desirable. Neutron radiography (NRG) is one of the powerful tools for gas-liquid two-phase flow measurement and void fraction distribution can be estimated from the acquired images. However, the temporal resolution of NRG is about 100∼1, 000 Hz depending on the neutron flux and it should be increased to investigate flow dynamics. So the authors focused on a hybrid measurement of the NRG and a conductance liquid film sensor (LFS). The combination of these methods can complement the spatial and temporal information of the flow. In this study, the hybrid measurements were performed by NRG and LFS to visualize the detailed structure of narrow two-phase flow.

The present paper describes gas-liquid two-phase flow measurements in a packed bed of spheres using neutron radiography. Porous debris formed during a severe accident of a nuclear reactor should be cooled by a coolant and the cooling characteristics are dominated by two-phase flow behavior in the debris bed at the initial stage of the accident. Therefore, experimental database of the two-phase flow in the porous media has been required for safety analysis of the reactor. However, it is difficult to observe the flow structure, for example, void fraction distribution in such complex flow channel. In this study, the local void fraction in a packed bed which simulates the debris bed was measured by high frame-rate neutron radiography. Experiments were performed in air-water two-phase flow in a vertical pipe. Alumina spheres with 5 mm in diameter were packed randomly in the pipe. The bubble behavior between the spheres was investigated by using the void fraction distributions estimated from the neutron radiographs. Although it was difficult to track the small bubbles in the packed bed, the move of the large bubble could be found roughly from the distribution. In addition, the fluctuation of the void fraction was compared with that of the pressure drop in the test section. From these results, the possibility of the gas velocity estimation was shown.

Most mono-propellant thruster technologies were developed in the 1960s. Those basic principles and fundamental mechanisms, such as the catalyst and propellant, are still in use without major technical innovation. However, much remains to be clarified in terms of the mechanisms and quantitative limitations of the hydrazine decomposition phenomena inside the mono-propellant thruster. Therefore, in order to enhance the reliability of the propulsion systems, it should be promising to perform the direct observation of the physical and chemical phenomena occurring in the catalyst bed of the mono-propellant thruster. For that purpose, a visualization of the mono-propellant thruster was performed by using high frame-rate neutron radiography technique. The experiments were conducted at the Kyoto University Research Reactor and the hydrazine injection behavior to the catalyst bed was visualized clearly.

High frame rate neutron radiography has been utilized to investigate two-phase flow in a metallic duct. However, images obtained by high frame-rate neutron radiography suffered from severe statistical noise due to its short exposure time. In this study, a spatio-temporal filter was applied to reduce the noise in the sequence images obtained by high frame-rate neutron radiography. Experiments were performed at the B4-port of the Research Reactor Institute, Kyoto University, which has a thermal neutron flux of 5.0×10[7] n/cm[2]s. Results were also compared with those obtained at the JRR-3, the Japan Atomic Energy Institute, with athermal neutron flux of 1.6×10[8]n/cm[2]s.

A newly developed flat heat pipe FGHPTM (Morex Kiire Co.) was experimentally investigated by using neutron radiography. The test sample of the FGHP heat spreader was 65 × 65 × 2 mm3 composed of several etched copper plates and pure water was used as the coolant. Neutron radiography was performed at the E-2 port of the Kyoto University Research Reactor (KUR). The coolant distributions in the wick area of the FGHP and its heat transfer characteristics were measured at heating conditions. Experimental results show that the coolant distributions depend slightly on its installation posture and that the liquid thickness in the wick region remains constant with increasing heat input to the FGHP. In addition, it is found that the wick surface does not dry out even in the vertical posture at present experimental conditions., Proceedings of the 10th World Conference on Neutron Radiography (WCNR-10) Grindelwald, Switzerland October 5–10, 2014

In order to clarify the water-accumulation phenomena in an operating polymer electrolyte fuel cell (PEFC), the water distribution in a small fuel cell was measured in the through-plane direction by using neutron radiography. The fuel cell had nine parallel channels for classifying the water-accumulation process in the gas diffusion layer (GDL) under the lands and channels. The experimental results were compared with numerical results. The water accumulation in the GDL under the lands was larger than that under the channels during the period of early PEFC operation. The difference of the water accumulation in the GDL under the land and channel was related to the water vapor. Because of the land, the vapor fraction in the GDL under the land was also higher than that under the channel. As a result, condensation was easy to occur in the GDL under the land., Proceedings of the 10th World Conference on Neutron Radiography (WCNR-10) Grindelwald, Switzerland October 5–10, 2014

In order to clarify the water-accumulation phenomena in an operating polymer electrolyte fuel cell (PEFC), the water distribution in a small fuel cell was measured in the through-plane direction by using neutron radiography. The fuel cell had nine parallel channels for classifying the water-accumulation process in the gas diffusion layer (GDL) under the lands and channels. The experimental results were compared with numerical results. The water accumulation in the GDL under the lands was larger than that under the channels during the period of early PEFC operation. The difference of the water accumulation in the GDL under the land and channel was related to the water vapor. Because of the land, the vapor fraction in the GDL under the land was also higher than that under the channel. As a result, condensation was easy to occur in the GDL under the land.

Adsorption refrigerator is one of the efficient tools for waste heat recovery, because the system is driven by heat at relative low temperature. However, the coefficient of performance is low due to its batch operation and the heat capacity of the adsorber. In order to improve the performance, it is important to optimize the configuration to minimize the amount of driving heat, and to clarify adsorption/desorption phenomena in transient conditions. Neutron radiography was applied to visualize and measure the adsorption amount distribution in an adsorber. The visualization experiments had been performed at the neutron radiography facility of E-2 port of Kyoto University Research Reactor. Activated carbon and ethanol were used as the adsorbent and refrigerant. From the acquired radiographs, adsorption amount was quantitatively measured by applying the umbra method using a checkered neutron absorber with boron powder. Then, transient adsorption and desorption processes of a rectangular adsorber with 84 mm in width, 50 mm in height and 20 mm in depth were visualized. As the result, the effect of fins in the adsorbent layer on the adsorption amount distribution was clearly visualized.

A newly developed flat heat pipe FGHPTM (Morex Kiire Co.) was experimentally investigated by using neutron radiography. The test sample of the FGHP heat spreader was 65 × 65 × 2 mm3 composed of several etched copper plates and pure water was used as the coolant. Neutron radiography was performed at the E-2 port of the Kyoto University Research Reactor (KUR). The coolant distributions in the wick area of the FGHP and its heat transfer characteristics were measured at heating conditions. Experimental results show that the coolant distributions depend slightly on its installation posture and that the liquid thickness in the wick region remains constant with increasing heat input to the FGHP. In addition, it is found that the wick surface does not dry out even in the vertical posture at present experimental conditions.

Dynamic behavior of a two-phase bubble, i.e. a steam bubble containing a droplet evaporating in the bubble, in the molten alloy was clearly visualized using high-frame-rate neutron radiography. In relation to some direct contact heat exchanger design with molten lead-bismuth (Pb-Bi), experiments have been done at JRR-3M of JAEA (Japan Atomic Energy Agency) with water droplets evaporating in a stable thermally stratified Newton's alloy pool. The instantaneous shape and size of the bubble has been iteratively estimated from the void fraction distributions and total void volume by assuming a symmetrical bubble shape.

Yasushi SaitoPresident, Chiba University, Chiba, JapanAbstract: Pitavastatin is a potent HMG-CoA reductase inhibitor and efficient hepatocyte low-density lipoprotein cholesterol (LDL-C) receptor inducer, producing robust reduction of the serum LDL-C levels, even at a low dose. Pitavastatin and its lactone form are minimally metabolized by CYP enzymes, and are therefore associated with minimal drug–drug interactions (DDIs). Pitavastatin 2 to 4 mg has potent LDL-C-reducing activity, equivalent to that of atorvastatin 10 to 20 mg; several clinical trials have revealed consistently superior high-density lipoprotein cholesterol (HDL-C) elevating activity of pitavastatin than that of atorvastatin. Pitavastatin-induced HDL-C elevation has been shown to be sustained, even incremental, in long-term clinical trials. Pitavastatin was as well-tolerated as atorvastatin or simvastatin in double-blind randomized clinical trials. Two-year long-term safety and effectiveness of pitavastain has been confirmed in a large-scale, prospective post-marketing surveillance. The safety and efficacy profile of pitavastatin is favorable for the treatment of dyslipidemia, especially in metabolic syndrome patients. In addition to control of LDL-C, adequate control of triglyceride (TG) and HDL-C, hypertension and hyperglycemia is also necessary in metabolic syndrome patients. Pitavastatin produces adequate control of LDL-C and TG, along with potent and incremental HDL-C elevation, with a low frequency of DDIs.Keywords: HMG-CoA reductase inhibitor, pitavastatin, eff icacy, safety, drug–drug interaction

Intimal thickening, commonly observed in atheromatous lesions, mainly consists of smooth muscle cells. The intimal smooth muscle cells have vastly different characteristics from those of medial smooth muscle cells. The major differences are their rapid growth property, their expression of a scavenger pathway and the autocrine system for growth factor in the intimal smooth muscle cells. The existence of an autocrine system is proved by the secretion of smooth muscle cells derived growth factor (SDGF). Intimal smooth muscle cells are considered to be derived from medial smooth muscle cells through migration from the media and proliferation in intima in vivo. The change from medial to intimal smooth muscle cells was proved by the co-culture system with endothelial cells in vitro. Their rapid growth is observed not only in intimal smooth muscle cells but also in medial smooth muscle cells from the aorta of diabetes mellitus. These findings indicate that smooth muscle cell phenotype change occurs in various stages during the formation of atherosclerosis, and that endothelial cells play an important role in the phenotype change., departmental bulletin paper