Search

For the mass production of astatine-211, a promising radiopharmaceutical for cancer treatment, the National Institute for Quantum and Radiological Science and Technology has proposed the innovative “Liquid Bismuth Target System.” The target window in this system must be made from a material that resists the highly corrosive liquid bismuth environment. To meet this requirement, a promising target window material was selected in corrosion experiments performed in stagnant liquid bismuth. Based on knowledge of corrosion in liquid lead–bismuth eutectic gained during the development of fast reactors and accelerator-driven subcritical systems, FeCrMo–alloy, FeCrAl–alloy, and austenitic stainless steel (as a reference) were selected as the specimen materials. Experiments were carried out under saturated dissolved oxygen and low oxygen conditions, and the corrosion behaviors of the specimens were evaluated, mainly by scanning electron microscopy. The FeCrAl–alloy exhibited the most excellent corrosion resistance, followed by FeCrMo–alloy. Both materials are suitable candidates for the target window. Although austenitic stainless steel was less corrosion resistant than the former two materials, it is a likely applicable for the target window under appropriately limited operation conditions (such as irradiation current and exposure time) of the liquid bismuth target system.

C(aryl)–P bond cleavage via addition of phosphine to alkynyl ester in the presence of water.

This paper describes the outline and development plan for “Advanced Reactor Knowledge- and Artificial Intelligence (AI)-aided design integration approach through the whole plant lifecycle (ARKADIA),” which the Japan Atomic Energy Agency has begun developing to transform advanced nuclear reactor design to meet expectations of a safe, economic, and sustainable carbon-free energy source. ARKADIA will realize AI-aided integrated numerical analysis to offer the best possible solutions for any challenge that could arise in the design and operation of a nuclear plant, including optimization of safety equipment as well as structures, systems, and components. State-of-the-art numerical simulation technologies and a knowledge base that stores data and insights from past nuclear reactor development projects and R&D are integrated with AI. In the first phase of development, ARKADIA-design and ARKADIA-safety will be constructed individually, with the first target of a sodium-cooled reactor. In a subsequent phase, everything will be integrated into a single entity that is technology inclusive and applicable not only to advanced rectors with a variety of concepts, coolants, configurations, and output levels but also to existing light-water reactors.

Duality cascades are a series of duality transformations in field theories, which can be realized as the Hanany-Witten transitions in brane configurations on a circle. In the setup of the ABJM theory and its generalizations, from the physical requirement that duality cascades always end and the final destination depends only on the initial brane configuration, we propose that the fundamental domain of supersymmetric brane configurations in duality cascades can tile the whole parameter space of relative ranks by translations, hence is a parallelotope. We provide our arguments for the proposal., Comment: 37 pages, 9 eps figures; v2: section 2.2 added, four figures added

A rapid HPLC-UV method was developed for the quantitative analysis of kojic acid contained in fungal agar media. The methanol extract from fungal agar media was diluted with acetic acid aqueous solution and injected into HPLC. The separation was achieved on a C18 column within 10 minutes in an isocratic mode. The mobile phase was composed of water, methanol, and acetic acid. Spike and recovery tests were done using three representative agar media, and accuracy, precision and limit of detection were preferable. The developed method was applicable for the analysis of kojic acid in two Aspergillus strains practically, showing the usability of this method to evaluate the fungal ability to produce a beneficial secondary metabolite, kojic acid.

One of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors is eutectic reactions between boron carbide (B4C) and stainless steel (SS) as well as its relocation. Such behaviors have never been simulated in CDA numerical analyses in the past, therefore it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study focuses on B4C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in a range from solid to liquid state. The physical model is developed for a CDA computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies conducted until 2019. Specific results in this paper are the validation of physical model describing B4C-SS eutectic reaction in the CDA analysis code, SIMMER-III, through the numerical analysis of the B4C-SS eutectic melting experiments in which a B4C block was placed in a SS pool.

This paper describes the outline and development plan for “Advanced Reactor Knowledge- and AI-aided Design Integration Approach through the whole plant lifecycle (ARKADIA),” which the Japan Atomic Energy Agency has begun developing for the purpose of transforming advanced nuclear reactor design to meet expectations of a safe, economic, and sustainable carbon-free energy source. ARKADIA will realize artificial intelligence (AI)-aided integrated numerical analysis to offer the best possible solutions for any challenge that could arise in the design and operation of a nuclear plant, including optimization of safety equipment as well as structures, systems, and components. State-of-the-art numerical simulation technologies and a knowledge base that stores data and insights from past nuclear reactor development projects and R&D are integrated with AI. In the first phase of development, ARKADIA-Design and ARKADIA-Safety will be constructed individually, with the first target of a sodium-cooled reactor. In a subsequent phase, everything will be integrated into a single entity that is technology inclusive and applicable not only to advanced rectors with a variety of concepts, coolants, configurations, and output levels but also to existing light-water reactors.

We develop a package that ensures quality complying with AEC-Q 100 Grade 2 which is in-vehicle quality from various flip chip mounting methods and bump sealing technology with underfill resin and mold resin. FC CSP with heat spreader mounted on the product which has started mass production since last year is in the lineup, The heat dissipation can be improved by attaching the heat spreader directly to the chip backside which are heat sources and the Thermal Interface Material (TIM), using our assembly technology of flip chip mounting and molding the periphery while exposing the chip backside. By adjusting the Coefficient of Thermal Expansion (CTE) and thickness of the material, we realize low warpage and low coplanarity at reflow temperature and product use temperature environment and reduce package displacement behavior, we will improve the secondary mountability to the motherboard and provide reliable packages. Furthermore, it can be applied to SiP modules. It is also possible to construct multiple chip modules by mounting multiple ICs or placing low-passive components around them. We will consider heat spreader mounting on multiple ICs that generate heat, and metal coating on the entire SiP module to have a structure that achieves both heat dissipation and electromagnetic shielding as a future idea.

Herein, the wall shear stress in a double contraction nozzle has been evaluated experimentally to produce a liquid lithium (Li) target as a beam target for intense fusion neutron sources such as the International Fusion Materials Irradiation Facility (IFMIF), the Advanced Fusion Neutron Source (A-FNS), and the DEMO Oriented Neutron Source (DONES). The boundary layer thickness and wall shear stress are essential physical parameters to understand erosion–corrosion by the high-speed liquid Li flow in the nozzle, which is the key component in producing a stable Li target. Therefore, these parameters were experimentally evaluated using an acrylic mock-up of the target assembly. The velocity distribution in the nozzle was measured by a laser-doppler velocimeter and the momentum thickness along the nozzle wall was calculated using an empirical prediction method. The resulting momentum thickness was used to estimate the variation of the wall shear stress along the nozzle wall. Consequently, the wall shear stress was at the maximum in the second convergent section in front of the nozzle exit.

This paper describes evaluation results of thermophysical properties of stainless steel (SS) containing 5 mass % boron carbide (B4C) in its solid phase. First, the authors synthesized SS-B4C sample...

9Cr-ODS steel claddings consisting of tempered martensitic matrix, showed prominent creep rupture strength at 1000 °C, which surpassed that of heat-resistant austenitic steels although creep rupture strength of tempered martensitic steels is generally lower than that of austenitic steels at high temperatures. The measured creep rupture strength of 9Cr-ODS steel claddings at 1000 °C was higher than that from extrapolated creep rupture trend curves formulated using data at temperatures from 650 to 850 °C. This superior strength seemed to be owing to transformation of the matrix from the α-phase to the γ-phase. The transient burst strengths for 9Cr-ODS steel were much higher than those for 11Cr-ferritic/martensitic steel (PNC-FMS). Cumulative damage fraction analyses suggested that the life fraction rule can be used for the rupture life prediction of 9Cr-ODS steel and PNC-FMS claddings in the transient and accidental events with a certain accuracy.

New results are reported on the simulation of the rise of a deforming gas bubble surrounded by a liquid exhibiting a blend of shear-thinning and viscoelastic properties. A new hybrid model has been developed which combines the Carreau model for emulating the shear-thinning property of the liquid with the Chilcott–Rallison (FENE-CR) model for treating the viscoelastic property of the liquid. The new hybrid model allows one to independently prescribe the shear-thinning and viscoelastic properties (parameters) to be used in a simulation. Computations are implemented using the coupled level-set and volume-of-fluid (CLSVOF) method for tracking the deforming gas-liquid interface. The interfacial jump conditions are enforced with the sharp interface approach. In this study, four parameters, the Eotvos number, Carreau model parameter for slope of decreasing viscosity, Deborah number, and viscoelastic polymer dumbbell length parameter, are varied in order to gain understanding for gas bubble morphology in liquids exhibiting both shear-thinning and viscoelastic properties. It is found that the extent of bubble deformation and the liquid stress field are strongly dependent on these 4 parameters with minimal correlation between the shear-thinning and viscoelastic parameters. The ability to vary shear-thinning and viscoelastic parameters independently of one another in the new hybrid Carreau and FENE-CR model enables one to conveniently predict gas bubble behavior in complex liquid polymers by parameterizing the new model from basic measurements of the polymers.

Force potential exerting between two classical static sources of pure non-abelian gauge theory in the Coulomb gauge is reconsidered at a periodic/twisted box of size $L^3$. Its perturbative behavior is examined by the short-distance expansion as well as by the derivative expansion. The latter expansion to one-loop order confirms the well-known change in the effective coupling constant at the Coulomb part as well as the Uehling potential while the former is given by the convolution of two Coulomb Green functions being non-singular at $\bm{x}=\bm{y}$. The effect of the twist comes in through its Green function of the sector., 18 pages, minor changes made and section 5 added

Brane configurations in a circle allow subsequent applications of the Hanany-Witten transitions, which are known as duality cascades. By studying the process of duality cascades corresponding to quantum curves with symmetries of Weyl groups, we find a hidden structure of affine Weyl groups. Namely, the fundamental domain of duality cascades consisting of all the final destinations is characterized by the affine Weyl chamber and the duality cascades are realized as translations of the affine Weyl group, where the overall rank in the brane configuration associates to the grading operator of the affine algebra. The structure of the affine Weyl group guarantees the finiteness of the processes and the uniqueness of the endpoint of the duality cascades. In addition to the original duality cascades, we can generalize to the cases with Fayet-Iliopoulos parameters. There we can utilize the Weyl group to analyze the fundamental domain similarly and find that the fundamental domain continues to be the affine Weyl chamber. We further interpret the Weyl group we impose as a "half" of the Hanany-Witten transition., Comment: 51 pages, 12 eps figures; v3: published version

It is a well-known result by Hanany and Witten that, when two five-branes move across each other, D3-branes stretching between them are generated. Later the same brane configurations played a crucial role in understanding the worldvolume theory of multiple M2-branes. Recently the partition function of multiple M2-branes was transformed to the Fredholm determinant for quantum algebraic curves, where the characteristic 3/2 power law of degrees of freedom is reproduced and the determinant enjoys a large symmetry given by exceptional Weyl groups. The large exceptional Weyl group reproduces the Hanany-Witten brane transitions and, besides, contains brane transitions unknown previously. Aiming at understanding the new brane transitions better, we generalize our previous study on the D5 quantum curve to the E7 case, which requires delicate handling of degeneracies. By combining the results of these two cases, we propose a "local" rule for the brane transitions., 33 pages, 8 eps figures; clarifications added

One of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors is eutectic reactions between boron carbide (B4C) and stainless steel (SS) as well as its relocation. Such behaviors have never been simulated in CDA numerical analyses in the past, therefore it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study focuses on B4C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in a range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies conducted until 2018. Specific results in this paper are boron concentration distributions of solidified B4C-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.

In a core disruptive accident scenario, boron carbide, which is used as control rod material, may melt below the melting temperature of stainless steel due to the eutectic reaction with it. Produced eutectic mixture is assumed to relocate widely in the degraded core, and this behavior plays an important role to reduce the neutronic reactivity of the degraded core materials significantly. However, these behaviors have never been simulated in the severe accident computer codes, and reducing the uncertainty is important for reasonable assessment. To contribute improvement of the core disruptive accident analysis code to handle these eutectic melting and relocation behavior, authors had been carried out the evaluation of the thermophysical properties of stainless steel containing boron carbide, which needed as a basic data for cord improvement. Since the solubility range of boron against iron is expected to be wide, the crystalline phase of eutectic mixture may change according to boron concentration in the eutectic mixture. And this may affect the thermophysical properties themselves. In this work, the density and specific heat of stainless steel containing 17 mass% boron carbide in a solid state are obtained and compared with these of stainless steel containing 0 and 5 mass% boron carbide. By adding 17 mass boron carbide to stainless steel type 316L, the density decreased approximately 24% and the specific heat increased approximately 25% at 293 K. The density of stainless steel containing boron carbide tended to decrease almost linearly depending on the amount of boron carbide added, none the less for difference of crystalline phase. On the other hand, increasing trend of the specific heat of stainless steel containing 17 mass% boron carbide accompanying elevating temperature showed different behavior from that of stainless steel containing 0 and 5 mass% boron carbide. This difference in the trend of the specific heat was considered to be caused the difference in the crystalline phase.

Phosphatidylcholine (PC) is the major phospholipid in meat and influences meat qualities, such as healthiness. PC is classified into three groups based on the bond at the sn-1 position: Diacyl, alkylacyl, and alkenylacyl. To investigate their composition and distribution in pork tissues, including longissimus thoracis et lumborum (loin) spinalis muscles, intermuscular fat, and transparent tissues, we performed matrix-assisted laser desorption/ionization&ndash, mass spectrometry imaging (MALDI&ndash, MSI). Eleven diacyl-, seven alkylacyl-, and six alkenylacyl-PCs were identified using liquid chromatography (LC)-tandem MS (MS/MS) analysis. Despite many alkylacyl- and alkenylacyl-PC species sharing identical m/z values, we were able to visualize these PC species using MALDI&ndash, MSI. Diacyl- and alkylacyl- and/or alkenylacyl-PC species showed unique distribution patterns in the tissues, suggesting that their distribution patterns were dependent on their fatty acid compositions. PCs are a major dietary source of choline in meat, and the amount was significantly higher in the muscle tissues. Consumption of choline mitigates age-related memory decline and neurodegenerative diseases, therefore, the consumption of pork muscle tissues could help to mitigate these diseases. These results support the use of MALDI&ndash, MSI analysis for assessing the association between PC species and the quality parameters of meat.

Summary Aflatoxin contamination of crops is a serious problem worldwide. Utilization of aflatoxin production inhibitors is attractive, as the elucidation of their modes of action contributes to clarifying the mechanism of aflatoxin production. Here, we identified mitochondrial protease ClpP as the target of dioctatin, an inhibitor of aflatoxin production of Aspergillus flavus. Dioctatin conferred uncontrolled caseinolytic capacity on ClpP of A. flavus and Escherichia coli. Dioctatin-bound ClpP selectively degraded mitochondrial energy-related proteins in vitro, including a subunit of respiratory chain complex V, which was also reduced by dioctatin in a ClpP-dependent manner in vivo. Dioctatin enhanced glycolysis and alcohol fermentation while reducing tricarboxylic acid cycle metabolites. These disturbances were accompanied by reduced histone acetylation and reduced expression of aflatoxin biosynthetic genes. Our results suggest that dioctatin inhibits aflatoxin production by inducing ClpP-mediated degradation of mitochondrial energy-related components, and that mitochondrial energy metabolism functions as a key determinant of aflatoxin production.

A calculation model was constructed to systematically study the effects of environmental conditions (i.e. Cr concentration in sodium, test temperature, axial temperature gradient of fuel pin, and sodium flow velocity) on Cr dissolution behavior. Chromium dissolution was largely influenced by small changes in Cr concentration (i.e. chemical potential of Cr) in liquid sodium in the model calculation. Chromium concentration in sodium coolant, therefore, should be recognized as a critical parameter for the prediction and management of Cr dissolution behavior in the sodium-cooled fast reactor (SFR) core. Because the fuel column length showed no impact on dissolution behavior in the model calculation, no significant downstream effects possibly take place in the SFR fuel cladding tube due to the much shorter length compared with sodium loops in the SFR plant and the large axial temperature gradient. The calculated profile of Cr concentration along the wall-thickness direction was consistent with that measured in BOR-60 irradiation test where Cr concentration in sodium bulk flow was set at 0.07 wt ppm in the calculation., 高温流動Na中での燃料被覆管からのCr溶出挙動に及ぼす各種試験パラメータ(Na中溶存Cr濃度、試験温度、軸方向温度勾配、Na流速)の影響を系統的に把握するための計算モデルを構築し、数値計算を行った。Cr溶出挙動が液体Na中の溶存Cr濃度の微量の変化に大きく影響される計算結果を得た。Na中のCr濃度は、Na冷却高速炉(SFR)内における燃料被覆管からのCr溶出挙動の予測・制御のため、注目すべき重要なパラメータであると考えられる。Na中溶存Cr濃度を0.07wtppmmとした場合の本モデル計算で得たODS鋼被覆管肉厚方向のCr濃度プロファイルは、BOR-60照射試験データとよく一致した。

We developed a diagnostics tool for a liquid lithium (Li) target intended for use in intense fusion neutron sources such as the International Fusion Materials Irradiation Facility (IFMIF). The current design of IFMIF requires that the thickness of the liquid-Li target be maintained to within ±1 mm while operating under normal conditions. This paper deals with two topics: a conceptual design of the Li target diagnostics and verification tests of a candidate diagnostics (long-distance LP system). The overall concept of the Li target diagnostics is described first, and then the system configuration of the long-distance LP method, which is to be installed 7 m in front the Li target to measure the Li target thickness accurately, is shown. In addition, we present the results of verification tests aiming to examine the applicability of the long-distance LP system. The precision error resulting from long-distance measurement was estimated using a stationary specular-reflection object and a water-model simulating the Li target. As a result, we verified that the LP system has a precision of 16–40 μm even at a sampling rate of 500 kHz measurement from a distance of 10 m.

A liquid Li free-surface stream flowing at 15 m/s under a high vacuum of 10 −3 Pa is to serve as a beam target (Li target) for an intense neutron source such as the planned International Fusion Materials Irradiation Facility (IFMIF). This study examines cavitation-like acoustic noise occurring upstream of the Li target. This noise is detected using an acoustic emission sensor that is installed at a Li target assembly in which the Li target was produced. A time-frequency analysis by continuous wavelet transform (CWT) was performed to characterize the acoustic noise, which determined the cause of the acoustic signal was cavitation. And the occurrence of cavitation was discussed by using Bernoulli’s equation and compared with the experimental observations. As a consequence, we revealed a criterion of inception of cavitation and a proper startup pressure of the Li target, which will be a design basis for the future IFMIF Li target facility.

To show the Hertz-Knudsen equation is applicable to the prediction of the evaporation rates of Li and volatile impurities from the Li target surface at the International Fusion Materials Irradiation Facility (IFMIF), we analytically and experimentally studied these rates for a high-speed Li jet via engineering-scale tests performed under IFMIF conditions (vacuum pressure: 10−3 Pa, Li temperature: 250 °C, jet speed: 7–15 m/s). The rates of evaporation and deposition were analytically predicted using the Hertz–Knudsen equation and the cosine law with known Li impurity concentrations (36 wppm for Na and 10 wppm or less for K). As pointed out in earlier works, Na and K are volatile impurities in Li. The evaporation rates of Na and K from liquid Li at a temperature of 250 °C are non-negligible, even if their concentrations in Li are as small as tens of wppm. To measure the deposition rate of evaporants from the Li jet, we used a quartz crystal microbalance and a neutralization titration method. The measured deposition rate was highly consistent with the deposition rate estimated analytically for weak evaporation. Also, the measured deposition rate was independent of the flow speed in the range of 7–15 m/s. We concluded that combining the Hertz–Knudsen equation and the cosine law is a reliable method for predicting the evaporation and deposition rates of Li and volatile impurities from a Li jet surface at the IFMIF.