Wettability Improvement by Plasma Irradiation and Its Applications to Phase-Change Phenomena

Plasma irradiation is one of the techniques to improve surface wettability. This technique can be used to enhance heat transfer of liquid–vapor phase change. For instance, evaporation of a water droplet can be enhanced by plasma irradiation. The relation between plasma irradiation time and contact angle was examined first for three metals and then the lifetime of a water drop on a hot surface was measured changing the surface wettability by plasma irradiation. The lifetime of the water drop decreased and the wetting limit temperature increased with the increasing irradiation time of plasma. Hydrophilicity by plasma irradiation is not a permanent effect but it will be useful for enhancement of cooling of hot metal.     

Source term estimation of atmospheric release due to the Fukushima Dai-ichi Nuclear Power Plant accident by atmospheric and oceanic dispersion simulations

The source term of the atmospheric release of ¹³¹I and ¹³⁷Cs due to the Fukushima Dai-ichi Nuclear Power Plant accident estimated by previous studies was validated and refined by coupling atmospheric and oceanic dispersion simulations with observed ¹³⁴Cs in seawater collected from the Pacific Ocean. By assuming the same release rate for ¹³⁴Cs and ¹³⁷Cs, the sea surface concentration of ¹³⁴Cs was calculated using the previously estimated source term and was compared with measurement data. The release rate of ¹³⁷Cs was refined to reduce underestimation of measurements, which resulted in a larger value than that previously estimated. In addition, the release rate of ¹³¹I was refined to follow the radioactivity ratio of ¹³⁷Cs. As a result, the total amounts of ¹³¹I and ¹³⁷Cs discharged into the atmosphere from 5 JST on March 12 to 0 JST on March 20 were estimated to be approximately 2.0 × 10¹⁷ and 1.3 × 10¹⁶ Bq, respectively.     

Function and 3D Structure of the N-Glycans on Glycoproteins

Glycosylation is one of the most common post-translational modifications in eukaryotic cells and plays important roles in many biological processes, such as the immune response and protein quality control systems. It has been notoriously difficult to study glycoproteins by X-ray crystallography since the glycan moieties usually have a heterogeneous chemical structure and conformation, and are often mobile. Nonetheless, recent technical advances in glycoprotein crystallography have accelerated the accumulation of 3D structural information. Statistical analysis of "snapshots" of glycoproteins can provide clues to understanding their structural and dynamic aspects. In this review, we provide an overview of crystallographic analyses of glycoproteins, in which electron density of the glycan moiety is clearly observed. These well-defined N-glycan structures are in most cases attributed to carbohydrate-protein and/or carbohydrate-carbohydrate interactions and may function as "molecular glue" to help stabilize inter- and intra-molecular interactions. However, the more mobile N-glycans on cell surface receptors, the electron density of which is usually missing on X-ray crystallography, seem to guide the partner ligand to its binding site and prevent irregular protein aggregation by covering oligomerization sites away from the ligand-binding site.     

Discovering Error Classes from Discrepancies in Novice Behaviors Via Multistrategy Conceptual Clustering

The automatic discovery of classes of errors that represent misconceptions and other knowledge errors underlying discrepancies in novice behavior is not a trivial task. A novel approach to this problem is described, in which relationships among behavioral discrepancies are analyzed and inductively generalized via an unsupervised, incremental, relational multistrategy conceptual clustering method that takes into account similarities as well as causalities in the data. Performance results on the classification of discrepancy sets and discovery of error classes from discrepancies of buggy PROLOG programs demonstrate the potential of the approach.     

用氧化镁铝热还原原位产生的镁蒸气改善铁水脱氧效率

提出了一种用氧化镁铝热还原原位产生的镁蒸气进行铁水脱氧的新方法.建立了反应模型来研究控速机理和镁蒸气的脱氧效率.模型计算结果显示,要获得高脱氧效率,必须控制喷吹气泡中的镁蒸气压力.     

Applicability of performance improvement method of existing steel railway bridges by installing concrete decks

Steel railway bridges which exceed their design lifetime are increasing in Japan, and some of them have problems such as corrosion and fatigue. In this study, we proposed a method to improve the performance, such as the load-carrying capacity, of the existing steel railway bridges by installation of concrete decks. To figure out the applicability of the proposed method, we discussed the applicable range of span and the effect of stress reduction. Considering application into actual bridges, we proposed an installation method using pre-cast concrete decks and girder-deck connection with filler mortar and steel fasteners. Finally, we carried out loading tests of the connection with fasteners and bending tests of the applied girders. As a result, we found that the girder-deck connections have enough static capacity for lateral force and train loads, under the condition that the studs are installed and the gaps between the pre-cast decks are filled with mortar.     

Defects in banded spherulites of polymers

In order to investigate the detailed structure of a banded spherulite observed by polarized light microscopy, we develop a new image processing technique that can visualize defects (band defects) in the concentric bands and determine the growing directions of crystals everywhere in a spherulite. This technique is applied to a banded spherulite of poly(vinylidene fluoride) and reveals that the spherulite has many defects (colliding defects), on which crystals collide with neighboring ones. It is found that the band defects are included in the colliding defects. The number of colliding defects increases linearly with the radius to give a constant density. Between the defects, the orientations of crystals are well correlated to form a coherent area. On the basis of these findings, a mechanism of the formation of the coherent band pattern is discussed.     

An Assessment and Estimation of the Damage Progression Behavior of IN738LC under Various Applied Stress Conditions Based on EBSD Analysis

In order to characterize the damage progression behavior of IN738LC and the influence of applied stress, the average misorientation within grains was evaluated using the electron backscattered diffraction (EBSD) method, by measuring over a million data points located across almost the whole zone of the tested specimens. It has been shown under various test conditions such as differing temperatures and strain rates that the average misorientation increases linearly with the increase of creep strains. As a result, it is confirmed that it is possible to assess the remaining creep fracture life from its average misorientation value regardless of the testing temperature and strain rate. In addition, the deformation and fracture mechanisms of various types of mechanical damage, such as tensile, impact, and creep conditions, were discussed by evaluating the characteristics of misorientation distribution. As a result, it has been revealed that creep damage affects a large area of the material, but it is localized near grain boundaries, which is completely different from that of tensile or impact damage. In conclusion, detailed investigation into the cross section of fracture samples using the EBSD misorientation analysis allows for the qualitative estimation of the fracture mode under various applied stress conditions, the cause of the fracture.     

Interface profile optimization in novel surface passivation scheme for InGaAs nanostructures using Si interface control layer

This paper attempts to control and optimize the interface atomic profiles of a novel surface passivation scheme for InGaAs nanostructures, using a silicon interface control layer (ICL). An in-situ x-ray photoelectron spectroscopy characterization technique was used to establish a process sequence that satisfies the conditions of maintenance of pseudomorphic matching to InGaAs, prevention of direct oxidation of InGaAs, and formation of a good SiO₂/Si interface with minimal suboxide components. It is shown that the above conditions can be satisfied by a new process that is a formation of the thermal SiO₂ at the SiO₂-Si interface by repetition of deposition/oxidation/annealing cycle. A large reduction of interface state density (N_ss) was realized by the optimization of the new process, resulting in a minimum N_ss of 4 × 10¹¹ cm⁻² eV⁻¹. The silicon ICL technique was successfully applied to the passivation of InGaAs wire structures.