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The number of patients with dementia is increasing worldwide. Modifying risk factors may significantly reduce the prevalence and cost of dementia. The number of remaining teeth, occlusal force, denture use, and periodontal disease status are associated with the risk of developing dementia. The oral environment may be a risk factor for dementia. This study aimed to investigate the association between the oral environment and cerebral blood flow in patients with mild cognitive impairment and dementia (either Alzheimer type dementia (ATD) or dementia with Lewy bodies (DLB)). We aimed to identify differences in the oral environment according to the underlying neurodegenerative disease.The participants were 25 patients with ATD and 25 patients with DLB who visited the Department of Dementia and Geriatric Medicine, Kanagawa Dental University Hospital. Patients were diagnosed with ATD and DLB by well-trained specialists certified by the Japanese Dementia Society and categorised as Level 3 or 4 by the Functional Assessment Staging of Alzheimer Disease scale. The correlation between oral environment (number of teeth, periodontal tissue, and oral function) and cerebral blood flow in each brain area calculated by single photon emission computed tomography was examined.The DLB group showed a significant correlation between masticatory performance and cerebral blood flow in some areas, while no such correlation was observed in the ATD group. Significant correlations were found between periodontal pocket depth and bleeding on probing and cerebral blood flow in some areas in both groups, although the correlation was considerable in the ATD group.The results of this study suggest that the association between changes in the oral environment and cerebral blood flow may differ among patients with ATD and DLB, depending on the underlying causative disease.

"Secondary doping" in poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) is quite effective and a frequently used method for the conductivity enhancement. This simple approach, the addition of co-solvents to the PEDOT:PSS solution before film fabrication, is an essential way to derive the high electrical performance of PEDOT:PSS, but the mechanism still remains unclear. In this study, nanoscale structural changes synchronized with the conductivity enhancement via secondary doping in PEDOT:PSS films were investigated. During secondary doping with ethylene glycol near the critical dopant concentration, non-crystalized PEDOT molecules uncoupled from PSS chains and then underwent nano-crystallization. These structural changes might be the key driving force for conductivity enhancement via secondary doping., 9 pages, 7 figures, accepted for publication in J. Phys. Chem. C

Copper-containing low-alloy steel based on the ASTM A707 5L grade is widely used for structural parts of offshore wells. However, it is difficult to stably obtain good weld joint toughness. With this background, this paper focuses on the metallurgical factors controlling the heat-affected zone (HAZ) toughness of A707 modified steel. Potential factors considered are the grain size, the martensite–austenite constituent (M-A), and precipitates. Thus, the purpose was to clarify the effect of M-A and precipitates on HAZ toughness. Furthermore, Cu, Si, and Mn contents, which affect M-A and precipitates generations, were focused on and tried to improve HAZ toughness by optimizing their contents in ASTM A707 steel. The weld test results showed that the toughness of an intercritically coarsened grain HAZ (ICRCGHAZ) was remarkably lower than that of the other heat cycle pattern due to the formation of M-A. It is, therefore, essentially important to suppress the formation of M-A in order to improve toughness in the HAZ of the steel. Therefore, the chemical composition was optimized in an effort to improve HAZ toughness. Copper had no negative influence on the HAZ toughness. It was found that when the Mn and Si contents of the steel decreased, the area fraction of M-A decreased. Consequently, the ICRCG HAZ toughness is improved because the toughness increases with the decrease in the area fraction of M-A. The recommended amounts of Cu, Mn, and Si to ensure HAZ toughness are more than 1.0 wt%, less than 0.6 wt%, and less than 0.1 wt%, respectively.

Nelson curve for carbon steel without post welding heat treatment (PWHT) was reconsidered in Annex F of API PR941 8th Edition because a lot of hydrogen damage cases of carbon steel for pressure vessels and pipes with weld joint were reported. However the mechanism of the damage initiation has not been extensively studied. For these reason, the purpose of this study was to clarify effect of residual stress on high temperature hydrogen attack (HTHA) and examine the mechanism in terms of microstructure. The specimens that were simulated welding residual stress by four point bending tool were exposed to high temperature and high pressure hydrogen gas to investigate relationship between damage initiation and condition of temperature and pressure. The frequency of damage occurred by residual stress under high temperature and low hydrogen pressure conditions was higher than that under low temperature and high pressure condition. The damage occurred on boundary of ferrite and pearlite. The grain reference orientation deviation (GROD) map obtained from EBSD measurement indicated the concentration of strain on the boundary generated by plastic deformation. Thus, the damage is most likely initiated by concentration of hydrogen on ferrite-pearlite boundary at which welding strain accumulated. Moreover the damage susceptibility of ferrite-pearlite structure was higher than that of bainite structure. The microstructures in base metal is ferrite-pearlite, but that in heat affected zone is bainite by reheating and cooling at welding. Hence, the base metal has higher damage susceptibility than HAZ.

Copper-containing low alloy steel based on ASTM A707 5L grade is widely used for structural parts of offshore wells. Applications of the steel for Ultra-deepwater development require excellent low temperature toughness from the viewpoint of marine accident prevention. However it is difficult to stably obtain good weld joint toughness because the welding condition is inevitably scattering. With those backgrounds, this paper focuses on metallurgical factors controlling the HAZ toughness of A707 modified steel. Potential factors considered are the grain size, M-A and precipitates. A challenge is demonstrated to improve the HAZ toughness by optimizing the Cu and Mn contents. In this study, we investigated mechanical properties including crack tip opening displacement (CTOD) and we observed microstructure using welding tests or various weld heat cycle specimens. The weld heat affected zone (HAZ) of a conventional material had good toughness for the low heat input condition. However it was remarkably decreased for the high heat input condition due to the precipitating martensite-austenite constituent (M-A) in local brittle zones (LBZ). The weld test results indicated the importance of suppressing the formation of M-A in order to improve toughness in the HAZ of the steel. Thereby, we challenged the optimization of chemical composition for HAZ toughness improvement. Cu had no bad influence on the HAZ toughness. It was demonstrated that the HAZ toughness is recovered by good use of Cu precipitates in SC cycle. Moreover the area fraction of M-A is decreased in keeping with Mn content, which leads to the improvement of the ICCG HAZ toughness. Based on our study, the recommended amounts of Cu and Mn are more than 1.0 mass% and less than 0.6 mass%, respectively, to ensure the HAZ toughness, especially ICCG HAZ toughness.

Effects by intercritical quenching, which is quenching from dual-phase of ferrite (α) and austenite (γ) region from 953 to 1068 K, on mechanical properties and microstructures of Cu-containing low alloy steel based on ASTM A707 5L grade (hereafter called A707 modified steel) were investigated using 50 kg test ingots. The mechanical properties of the A707 modified steel, i.e. strength at room temperature and fracture toughness at low temperature, were significantly improved by intercritical quenching. This is probably because its effective grain size decreased by intercritical quenching. Then, the optimum temperature of intercritical quenching for A707 modified steel was 1068 K near the AC3 point. Based on the experimental results of the test ingot, we applied intercritical quenching to a trial full-size forging production of about 20,000 mm in length, and researched the tensile, Charpy impact, crack tip opening displacement (CTOD) and drop weight test (DWT) properties across whole length of the trial production. It was found that the trial production has good mechanical properties across whole length. From the present work, an appropriate intercritical quenching is considered to apply for improvement method of the mechanical properties in A707 modified steel forgings.

Recently, higher steam inlet temperature and pressure has been required for fossil power plants in order to increase the power generation efficiency. Therefore, boron-bearing high-chromium (high-Cr) steels with higher long-term creep strength are applied to structure materials in these plants. Dissimilar (metal) weld joints between a boron-bearing high-Cr steel and a low-alloy steel are applied for various parts of boilers and other equipment in the plants. Caution has to be paid to maintain the quality of these weld joints because boron is diffused to the low-alloy steel weld deposits by dilution from the boron-bearing high-Cr base metal. However, the existing form of boron and the effect of boron on reheat cracking susceptibility during post-weld heat treatment (PWHT) have not been surveyed in the previous literature. Therefore, using Cr–Mo low-alloy steels with varied contents of B and Cr, reheat cracking susceptibility of the weld metal was evaluated, and the precipitation behaviour of the carbides du...

The correlation between the transport properties and structural degrees of freedom of conducting polymers is a central concern in both practical applications and scientific research. In this study, we demonstrated the existence of mesoscopic two-dimensional (2D) coherent charge transport in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film by performing structural investigations and high-field magnetoconductance (MC) measurements in magnetic fields of up to 15 T. We succeeded in observing marked positive MCs reflecting 2D electronic states in a conventional drop-cast film. This low-dimensional feature is surprising, since PEDOT:PSS-a mixture of two different polymers-seems to be significantly different from crystalline 2D materials in the viewpoint of the structural inhomogeneity, especially in popular drop-cast thick films. The results of the structural experiments suggest that such 2D transport originates from the nanometer-scale self-assembled laminated structure, which is composed of PEDOT nanocrystals wrapped by insulating sheets consisting of amorphous PSSs. These results indicate that charge transport in the PEDOT:PSS film can be divided into two regimes: mesoscopic 2D coherent tunneling and macroscopic three-dimensional hopping among 2D states. Our findings elucidate the hieratical nature of charge transport in the PEDOT:PSS film, which could provide new insight into a recent engineering concern, i.e., the anisotropic conductance., 11 pages, 8 figures, accepted for publication in Adv. Electron. Mater

Recently, boron bearing high chromium steel is applied to structural material of a fossil power generation plant. Dissimilar weld joints between this steel and low alloy steel are applied for various parts such as boiler or other equipments in this plant. In this weld joint, boron added to low alloy steel weld metals by the dilution from boron bearing base metal. However, the existence form of boron and the effect of boron on reheat cracking susceptibility during post weld heat treatment (PWHT) have not been surveyed in previous literature. So, reheat cracking test, precipitated carbide observation of boron bearing Cr-Mo low alloy steel weld metal was carried out in this study. From these test results, the reheat cracking susceptibility clearly increased by boron addition. Moreover, it decreased according to increasing chromium content. It was estimated that the structural form of boron was recognized in four kinds, such as BN, M2B, M23(C,B)6 and dissolved boron by thermo-dynamic calculation. The amount of M23C6 type carbide was increased with increasing chromium content. On the basis of these results, it was presumed that large amounts of dissolved boron existed in boron bearing low chromium steel weld metal compared with high chromium one during PWHT.Copyright © 2013 by ASME

The conductive organic polymer, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate), abbreviated as PEDOT:PSS, is widely used in capacitors, antistatic coating etc. and one of the potential materials for the next-generation printable electronics. It is because of its excellent dispersibility in water and high electronic conductivity of more than 1,000 S/cm. Although many preceding studies have provided a variety of possible mechanisms of high conductivity, such as charge transfer between PEDOT and residual solvents, there has been no conclusive explanation for the origin of the high conductivity. Here, we report the nanometer-size crystallization of PEDOT inside the hydrophobic core region of PEDOT:PSS in a solid film and enhancement of electronic conductivity caused by the nanometer-size crystal growth of PEDOT. The structure of PEDOT:PSS has been investigated by means of small- and wide-angle X-ray scatterings (SAXS and WAXS) using high brilliance synchrotron radiation light source in SPring-8, Japan. We have obtained the microscopic structural model of PEDOT:PSS micelle in the water dispersion and the solid polymer film (Fig. 1(a)). Nanometer-size crystals of PEDOT were grown during the course of film fabrication in the wet process from the water dispersion. Furthermore, we found that the better crystallinity of the PEDOT crystal in the films prepared in the different conditions resulted in the higher electrical conductivity (Fig. 1(b)). The result suggests that the size of the crystallite is one of the key parameters for the enhancement of the electronic conductivity in PEDOT:PSS films. These findings shed light on the further improvement of the electrical conductivity of PEDOT:PSS polymer films by controlling the evaporation to dryness in the wet fabrication process.