•A large improvement in the quench current is obtained in wet winding of REBCO wire with epoxy.•Epoxy impregnation is effective to stop degradation in the coil of polyimide-coated REBCO ...wire.•Classification of electromagnetic force-induced degradation in the REBCO coil was discussed.•A partially self-supported turn becomes a weak spot with regard to REBCO-conductor fracture.•Full infiltration of epoxy into the coil is keenly required to prevent degradation.
Recently, degradation of a high-field REBCO coil due to strong electromagnetic forces, has been identified. This issue is related to a conductor movement, forming a kink in the conductor body, and hence epoxy impregnation should be effective to prevent it. The purpose of this paper is to examine the effect of epoxy impregnation on the electromagnetic force-induced degradation of a REBCO coil. We made an epoxy impregnated solenoid coil and charged it at 4.2 K in an external field of 11 T. A notable characteristic behavior, which is different from that of a dry or paraffin impregnated coil, was observed in the coil’s performance. The coil did not show any normal voltage below 408 A, at 65% on the coil load line, but it showed a sudden voltage jump at 408 A, resulted from a sudden fracture of the REBCO conductor. The outward bending, combined with a strong circumferential stress, caused the REBCO layer to fracture. Although epoxy impregnation is effective to suppress a conductor movement inside the winding, avoiding self-supported sites at a coil edge is required to eliminate degradation of the thin and flexible REBCO conductor.
When using the superconducting technology industrially, it is not always possible to install a refrigerator near a high temperature superconducting coil for cooling it. In the method using heat ...conduction cooling, cooling result as expected cannot be obtained due to temperature difference between a refrigerator and a superconducting coil via a heat transfer plate when the distance of the refrigerator and the coil is long. Therefore, a method of cooling a superconducting coil by circulating helium gas has been proposed. Helium gas discharged by a compressor at room temperature is cooled by a pre-cooling heat exchanger, thereafter cooled by a GM refrigerator. The cold helium gas cools the coil and current leads. In this study, the helium circulation cooling system was investigated by using one-dimensional numerical analysis and experiment at different helium gas mass flows.
To observe and characterise vessel injury after stenting using optical coherence tomography (OCT), to propose a systematic OCT classification for periprocedural vessel trauma, to evaluate its ...frequency in stable versus unstable patients and to assess its clinical impact during the hospitalisation period.
Stenting causes vessel injury.
All consecutive patients in whom OCT was performed after stent implantation were included in the study. Qualitative and quantitative assessment of tissue prolapse, intra-stent dissection and edge dissection were performed.
Seventy-three patients (80 vessels) were analysed. Tissue prolapse within the stented segment was visible in 78/80 vessels (97.5%). Median number of tissue prolapse sites was 8 (IQR 4-19), mean (SD) area 1.04 (0.9) mm(2). Intra-stent dissection flaps were visible in 69/80 vessels (86.3%) (median number 3 (IQR 1.25-6), maximum flap length 450 (220) microm). Fifty-five out of 80 vessels (68.8%) showed dissection cavities (median number 2 (IQR 0-4.75), maximum depth 340 (170) microm). Edge dissection was visible in 20 vessels (mean (SD) length flap 744 (439) microm). The frequency of tissue prolapse or intra-stent dissection was similar in stable and unstable patients (95.6% vs 100%, p = 0.5 for tissue prolapse; 91.1% vs 82.9%, p = 0.3 for intra-stent dissection). There were no events during the hospitalisation period.
OCT allows a detailed visualisation of vessel injury after stent implantation and enables a systematic classification and quantification in vivo. In this study, frequency of tissue prolapse or intra-stent dissections after stenting was high, irrespective of the clinical presentation of the patients, and was not associated with clinical events during hospitalisation.
Fins are among the most important morphological appendages of aquatic animals. Although sall cetaceans have flippers and dorsal fins with a variety of morphologies and postures, the diversity and ...function of the fins have not attracted much attention thus far. In this study, we recorded the behaviour of five captive species of small cetaceans, including two species lacking dorsal fins, and examined the contribution of the dihedral angles of their flippers and dorsal fins in the lateral/directional inherent stability during straight‐line swimming. All the species were found to maintain their flippers at a specific negative dihedral angle during straight‐line swimming, and a significant difference was observed between species with and without dorsal fins: species without dorsal fins were found to swim by maintaining the dihedral angle of their flippers closer to 0° compared to species with dorsal fins. The rolling moment generated by the dihedral angle of the fins in all the species was a relatively small roll‐promoting moment that ensures manoeuvrability. In summary, small cetaceans are likely to have one of two characteristics, either left and right flippers with a near‐zero‐degree dihedral angle or a dorsal fin, to reduce the roll‐promoting moment. Our results highlight important aspects of swimming stability in dolphins, providing essential insights into the movement mechanisms of aquatic fish and mammals.
In this study, we recorded the behaviour of five captive species of small cetaceans, including two species lacking dorsal fins, and examined the contribution of the dihedral angles of their flippers and dorsal fins in the lateral/directional inherent stability during straight‐line swimming. All the species were found to maintain their flippers at a specific negative dihedral angle during straight‐line swimming, and a significant difference was observed between species with and without dorsal fins: species without dorsal fins were found to swim by maintaining the dihedral angle of their flippers closer to 0° compared to species with dorsal fins. In summary, small cetaceans are likely to have one of two characteristics, either left and right flippers with a near‐zero‐degree dihedral angle or a dorsal fin, to reduce the roll‐promoting moment. Our results highlight important aspects of swimming stability in dolphins, providing essential insights into the movement mechanisms of aquatic fish and mammals.
We report on our efforts to optimize the geometry of neutron moderators and converters for the TRIUMF UltraCold Advanced Neutron (TUCAN) source using MCNP simulations. It will use an existing ...spallation neutron source driven by a 19.3kW proton beam delivered by TRIUMF’s 520MeV cyclotron. Spallation neutrons will be moderated in heavy water at room temperature and in liquid deuterium at 20K, and then superthermally converted to ultracold neutrons in superfluid, isotopically purified 4He. The helium will be cooled by a 3He fridge through a 3He–4He heat exchanger.
The optimization took into account a range of engineering and safety requirements and guided the detailed design of the source. The predicted ultracold-neutron density delivered to a typical experiment is maximized for a production volume of 27L, achieving a production rate of 1.4 ⋅ 107s−1 to 1.6 ⋅ 107s−1 with a heat load of 8.1W. At that heat load, the fridge can cool the superfluid helium to 1.1K, resulting in a storage lifetime for ultracold neutrons in the source of about 30s. The most critical performance parameters are the choice of cold moderator and the volume, thickness, and material of the vessel containing the superfluid helium.
The source is scheduled to be installed in 2021 and will enable the TUCAN collaboration to measure the electric dipole moment of the neutron with a sensitivity of 10−27ecm.
Abstract Objective Serum 1,5-anhydro- d -glucitol (1,5-AG) is well-known to be a useful clinical marker of both short-term glycemic status and postprandial hyperglycemia. In addition, previous ...epidemiological studies have shown that an increased postload glucose level in an oral glucose tolerance test is a risk factor for cardiovascular diseases (CVD). However, no previous prospective study has reported the association between serum 1,5-AG levels and the risk of CVD. In this study, we examined whether serum 1,5-AG levels can predict the incidence of first-ever CVD. Methods Our study was a population-based cohort study in an urban area of Japan. Study subjects comprised 2095 initially healthy Japanese (991 men and 1104 women, mean age: 58.5 years) with no history of coronary heart disease (CHD) or stroke. They were followed up for an average of 11.1 years, and 147 CVD events (64 CHD and 83 strokes) were observed. Results The adjusted hazard ratios (HRs) of all CVD in men increased linearly ( p = 0.004). The HR in the category with serum 1,5-AG levels of 14.0 μg/mL or less was 2.22 (95% confidence interval; 1.24–3.98) compared to the reference category (24.5 μg/mL or greater). Similar results were also shown with a sensitivity analysis in non-diabetic men. Conversely, no significant relationship between serum 1,5-AG levels and CVD risks was observed in women. Conclusions Our results suggest that measurement of serum 1,5-AG levels is useful to detect individuals, especially men, at higher risk for CVD, regardless of the presence or absence of diabetes.
Separation of Cs and Sr from high-level liquid waste (HLLW) contributes to reducing heat generation and correspondingly to minimizing the required use of space in geological disposal repositories for ...high-level radioactive waste. To maximize the impact of Cs and Sr separation on reducing the occupied area of a repository, it is necessary to consider both the front-end and back-end stages of the nuclear energy system. Therefore, we quantitatively surveyed factors that potentially affect the reduction in the occupied area - that is, the area required for disposal of one waste package - when introducing Cs and Sr separation. From an evaluation using the Comprehensive Analysis of Effects on Reduction of Disposal Area (CAERA) index, we found that in case of a 15-year cooling period of spent nuclear fuel (SNF) after discharge, which is the current operational condition at the Rokkasho Reprocessing Plant, a maximum reduction of 30% in occupied area was achieved for 25 and 30 wt% waste-loaded vitrified waste with Cs and Sr separation. In that case, separation of more than 70% of Cs and Sr was required based on the current reference case for the Japanese geological disposal concept (the so-called H12 Report). In addition, the effectiveness of Cs and Sr separation for reducing the occupied area was drastically decreased if the cooling period after discharge was extended beyond 15 years; for instance, vitrified waste with a more than 40-year cooling period showed almost no reduction in occupied area. This was because the amount of
241
Am, which is generated from the beta decay of
241
Pu, and the contribution of
241
Am to heat generation in vitrified waste increased as the cooling period became longer. The results suggested that the cooling period of the SNF, the waste loading of the vitrified waste, the Cs and Sr separation ratio and the occupied area of the waste were key factors governing the effectiveness of Cs and Sr separation for geological disposal area reductions.
Recent studies identified that metabolically abnormal non-overweight phenotype is a risk factor for cardiovascular diseases. However, only little is known about risk factors for the progression from ...metabolically healthy non-overweight (MHNO) to metabolically abnormal phenotype. In this study, we investigated the impact of respiratory function on the progression from MHNO to metabolically abnormal phenotype.
In this retrospective cohort study, 8949 (3872 men and 5077 women) individuals with MHNO, who participated in a health-checkup program from 2004 to 2015, were enrolled. Four metabolic factors (high-normal blood pressure or hypertension, impaired fasting glucose or diabetes, hypertriglyceridemia, and low HDL cholesterol concentration) were used to define metabolically healthy (less than two factors) or metabolically abnormal (two or more factors) phenotypes. Respiratory function was measured by spirometry.
Over a median 4.0 years of follow-up, 927 participants progressed to metabolically abnormal phenotype. The percentage of FVC for predicted values (HR 0.98, 95% CI 0.93–1.03, p = 0.418) was not associated with the progression to metabolically abnormal phenotype after adjusting for covariates, including age, sex, alcohol consumption, exercise, smoking status, and body mass index, whereas the percentage of FEV1 for predicted values (%FEV1) (HR 0.87, 95% CI 0.84–0.91, p < 0.001) and the FEV1/FVC ratio (HR 0.86, 95% CI 0.78–0.95, p = 0.004) were associated with the progression to metabolically abnormal phenotype.
Decrease in respiratory function in terms of %FEV1 and the FEV1/FVC ratio is associated with the progression to metabolically abnormal phenotype in individuals with MHNO.
•Ten percent of MHNO progressed to metabolically abnormal (MA) phenotype.•%FEV1 and FEV1/FVC were associated with the progression to MA phenotype.•FVC, %FVC, and FEV1 were not associated with the progression to MA phenotype.
Experiments are performed on the flow past a sphere moving vertically at constant speeds in a salt-stratified fluid. Shadowgraph method and fluorescent dye are used for the flow visualization, and ...particle image velocimetry is used for the velocity measurement in the vertical plane. Vertical ‘jets’ or columnar structures are observed in the shadowgraph for all the Froude numbers Fr(0.2 ≲ Fr ≲ 70) investigated, and the wake structures in the whole parameter space of Fr and the Reynolds number Re(30 ≲ Re ≲ 4000) are classified into seven types, five of which are newly found. Those include two types of thin jets, one of which is short with its top disturbed by internal waves to have a peculiar ‘bell-shaped’ structure, while the other has an indefinitely long length. There are two other new types of jet with periodically generated ‘knots’, one of which is straight, while the other has a spiral structure. A simply meandering jet has also been found. These wake structures are significantly different from those in homogeneous fluids except under very weak stratification, showing that the stratification effects on vertical motion are much more significant than those on horizontal motion.
PDF
