The deformation of duplex structures in general and duplex stainless steels (DSS) in particular is very complex. The existence of the massive second phase leads to numerous unexpected features, i.e. the microstructure is the most decisive influence parameter on the deformation behavior of duplex structures. In the case of DSS additionally the chemical composition has to be taken into account.
With increasing rolling deformation at room temperature several deformation mechanisms occur, e.g. shear relaxation, twinning of austenite, deformation induced martensitic transformation of the austenitic phase, crack formation (and crack healing accompanied by the refinement of the microstructure) and dynamic recovery. In α/γ DSS additionally the phase boundaries (PB) are obstacles for deformation. Therefore, here large deformation zones were built up during deformation which contribute to the complex deformation behavior.
Since nitrogen reduces the SFE and, thereby, hardens the austenitic phase and promotes planar slip which is not homogeneously distributed in the austenitic grains but localized, ferrite becomes the more ductile phase in DSS. Furthermore, as a very strong austenite stabilizing element, N causes the change of the matrix phase form ferrite to austenite and leads to the ductile to brittle transition of austenite which also influences the deformation behavior.
It occurred that there are equal deformation modes like the hindrance of shear band formation, shear band cracking and "selective phase boundary sliding", which are obviously valid for all duplex structures, and other ones, due to the nitrogen content (e.g. brittleness) or the existence of the second phase (e.g. increased strain hardening rate).

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Two different nitriding surface treatments of austenitic stainless steel have been studied: gaseous nitriding in a NH₃-H₂ mixture performed at temperatures between 700 and 900°C and nitrogen ion implantation with different dose rates between 5×10¹⁶ to 1.5×10¹⁷ N₂⁺ ions cm^–2 and different current densities between 1 to 5 μA cm^–2. The microstructure of the coating was studied by X-ray diffraction and Mössbauer spectroscopy. The discussion emphasizes the role of thermodynamical equilibrium conditions at high temperatures and of the process parameters at low temperatures on the phases which constitute the layer.

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Fifty wt % of multiwall carbon nanotube (MWCNT) was blended with a conventional rubber compound to examine its effect on mechanical properties of the resulting composite, through the comparison with carbon black N and MWCNT/carbon black N (1/1) mixture as references. MWCNT resulted in a significant increase of elastic modulus, compared with N. It was revealed from microscopic surface analysis that a low dispersion of MWCNT in the rubber matrix was one of the causes of this favourable effect. The low dispersion of MWCNT, oppositely, brought about lower fracture elongation and fracture strength than in the case of N. The MWCNT/N mixture showed just intermediate effects between MWCNT and N.

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Anti-inflammatory effects of TSA- (recombinant human superoxide dismutase, rhSOD) were studied in vitroand in vivo. TSA-, 0.1-100 μg/ ml, significantly inhibited damage of chondrocytes, reduction inviscosity of hyaluronic acid and osteoarthrosis-derived joint fluid, delayed gelation of collagen and inactivation of α₁-proteinase inhibitor (PI) which were induced by active oxygen species generated in the system of hypoxanthine-xanthine oxidase. Intraarticular injection of TSA- significantly inhibited both carrageenin-induced arthritis in rabbit knees and sodium urate-induced arthritis in dog knees. Furthermore, TSA- significantly inhibited rat carrageenin-induced paw edema and mouse ischemic paw edema by 0.125-1 mg/kg, i. v. and 1 mg/kg, i. v., respectively.
These results suggest that TSA- will be useful with an Intraarticular injection on the therapy of osteoarthrosis in knees.

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試料から分離したウランについて,

234U

/

234U

比(γ:eU単位の比,α放射能比)を,αとβの放射能の関係から求める方法と,αスペクトルの解析から求める方法を検討した。αスペクトルによる²³⁸U/

234U

比の測定はラジウムとトリウムにより妨害を受ける。ウランの放射化学的精製が完全であることを確認するために,UX₁溶液または娘諸核種を含むMsTh₁溶液をトレーサーとして加えた。天然水中のウランはリン酸アルミニウムと共沈後,硝酸溶液から酢酸エチルで抽出,水で逆抽出したのち8N塩酸溶液としDowex 1 樹脂に通す。洗液(8N塩酸)中のトレーサーの放射能測定により,トリウムの完全除去を確認する。0.1N塩酸で溶離したウランを酢酸アンモニウム緩衝液からステンレス板上に電着して測定試料とした。αスペクトルによる方法を用い,島根県池田鉱泉周辺,鳥取県三朝温泉などの放射能泉,ウラン鉱床坑内水,ウラン鉱石についてγの測定を行ない,浅原鉱泉γ=1.6などの値を得るとともに,それらの値の地球化学的意味を考察した。

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Size-fractionated particulate

234Th

and particulate organic carbon (POC) fluxes were measured in the Gulf of Mexico during 2000 and 2001 in order to obtain a better estimation of upper ocean organic carbon export out of the euphotic zone within cold core and warm core rings, and to assess the relative merit of sediment trap and POC/

234Th

methods. In 2000, the flux of POC measured by sediment traps at 120 m ranged from 60 to 148 mg C m^-2d^-1, while

234Th

-derived POC fluxes in large particles (>53 μm) varied from 18 to 61 mg C m^-2d^-1 using the ratio of POC/

234Th

at 120 m, and from 51 to 163 mg C m^-2d^-1 using an average ratio of POC/

234Th

for the upper 120 m water column. In 2001, the fluxes of POC measured by traps deployed at 120 m water depth ranged from 39 to 48 mg C m^-2d^-1, while the

234Th

-derived POC fluxes in large particles (>53 μm) varied from 7 to 37 mg C m^-2d^-1 using a ratio of POC/

234Th

at 120 m, and from 37 to 45 mg C m^-2d^-1 using an average ratio of POC/

234Th

within the 0–120 m interval. The results show that POC fluxes estimated by the

234Th

method using the average ratio of POC/

234Th

within the euphotic zone are similar to those measured by sediment traps. Furthermore, the results demonstrate that the variability in POC export fluxes estimated by the

234Th

/²³⁸U disequilibrium approach is strongly related to the ratio of POC/

234Th

that is taken, and for which we have independent evidence that it may be controlled by the chemical composition of the suspended particles. The results also reveal that using POC/

234Th

ratios in small particles may result in an estimate of the POC export flux that is considerably higher than when using POC/

234Th

ratios in large particles (>53 μm). The POC flux calculated from ratios in large particles is, however, more comparable to the POC flux determined directly by sediment traps, but both of these estimates are much lower than that determined by using the POC/

234Th

ratios in sinking particles. Therefore, without reliable flux values to compare with,

234Th

-based and sediment trap approaches are complementary methods for estimating upper ocean POC export, with comparable uncertainties for both of these approaches.

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An analytical method for uranium and the results of measurement of ²³⁸U and

234U

in river waters on the eastern area in Japan are described in this report. The mean values of the concentration of ²³⁸U and of the activity ratio of

234U

/²³⁸U in 27 sample waters were 0.27 mBq/l and 1. 55, respectively. The unexpected

234U

/²³⁸U ratio, which was more than 2.0 in the range, was found in some waters. In general, as the activity ratio of

234U

/²³⁸U is low in surface water and high in deep aquifer, it was supposed that these river water may contain much amount of spring water from the mountain area.

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陽イオン交換樹脂を用いて,トリウムからプロトアクチニウムを容易に分離する方法が発見された.樹脂柱に吸着させた

234Th

(UX₁)から1～2Nの硝酸または0.1～0.7%のシュウ酸によって

234mPa

(UX₂)が溶離される.これらの条件では樹脂柱上端に吸着された

234Th

は,ほとんど移動しない.溶離曲線から,分布率(K_d)を概算した.その結果,硝酸によって溶離されるプロトアクチニウムはおそらく1価の陽イオン,PaO⁺₂であると推定される.一方,シュウ酸による溶離では,0.1%付近の溶離剤の濃度でイオンの状態が変化すると推測される.さらに,この方法を用いて,^23mPa(UX₂)の核異性体である

234Pa

(UZ)を

234Th

(UX₁)から分離することに成功した.

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This article reviews the recent studies on the export flux of particulate organic carbon (POC) from the euphotic zone to the deep sea using

234Th

(half-life, 24.1 days) and ²²⁸Th (half-life, 1.9 years) as natural tracers. The POC export flux estimated by the

234Th

method generally has a large error, propagated from uncertainties in the estimates of

234Th

flux and POC/

234Th

ratios in sinking particulate matter. In relatively low particle flux regime, where the surface water

234Th

is close to secular radioactive equilibrium with ²³⁸U, reducing errors in the

234Th

measurements becomes of primary importance and hence the analytical method should be chosen based not on convention but on precision of measurements. It may be worthwhile to use the longer-lived ²²⁸Th wherever possible in such cases. It is also clear that more efforts are needed to establish a relation between the rate of POC removal and

234Th

flux. Nonetheless, the natural variations of POC flux with location, season and depth, are large enough to make the

234Th

-based POC export fluxes to be significant in our understanding of the mechanism of "biological pump". Much of the ocean, like the equatorial Pacific and the oligotrophic regions where the sea conditions are stable, ThE defined as a ratio of

234Th

-based POC export to primary production (Buesseler, 1998) is low at 2〜10%, suggesting that POC is efficiently recycled within the euphotic zone. However, during bloom conditions at high latitudes and at mid-latitudes in spring, ThE approaches to 〜50%. Such high POC export flux most often occurs in food webs with primary producers dominated by large phytoplankton, particularly diatoms.

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In order to understand uranium migration behavior through geological media, the granitic conglomerate from the Tono uranium mine, Gifu prefecture, central Japan, was studied by grain size division and selective chemical leaching technique. The bulk contents of U and Th in fine-grained samples are larger than those of coarse-grained ones, and have positive correlations with the abundance of detrital biotite grains. The total amount of U eluted by the leaching reagents was more than half in all divided samples. In particular, a large amount of U was leached by sodium acetate/acetic acid (pH 5.0), and hydroxylamine hydrochloride/acetic acid solutions. It is inferred that carbonate and iron oxide minerals play an important role in U ore genesis. The adsorption density of fine-grained samples is larger than that of the coarse-grained one, which suggests that the fine U minerals are abundant in fine-grained sample and/or the U concentration around the complexing site of iron oxyhydroxides may have become high. The bulk

234U

/²³⁸U activity ratio is 0.95 ± 0.05, and the bulk ²³⁰Th/

234U

activity ratio is 1.36 ± 0.06. For most of the sieved samples,

234U

/²³⁸U activity ratios are <1, and ²³⁰Th/

234U

activity ratios are >1, showing that U is partially removed from the sediments. The uranium nuclides in the matrix of conglomerate are inferred to be not in equilibrium within 300, 000 y. The ion exchangeable U, whose

234U

/²³⁸U activity ratio was >1, is bound weakly and exchangeable with U in the surrounding water such as interstitial water and groundwater with

234U

/²³⁸U activity ratios >1. The

234U

/²³⁸U activity ratios of the residue fraction are less than 1 (finer sample) or more than 1 (coarser sample), indicating that the recoil ejection effect of U is advantageous for the fine-grained samples while injection effect is advantageous for the coarse-grained samples. The

234U

/²³⁸U activity ratios of other fractions are less than 1, which is quite similar to the bulk ratio. The ratio decreases in the order of carbonate > iron oxide > organic/sulfide fractions. The ²³⁰Th/

234U

activity ratios is very low in ion exchangeable fraction and >1 in carbonate, iron oxide, and residue fractions. For the residue fraction,

234U

/²³⁸U > 1 and ²³⁰Th/

234U

> 1 indicate the elution of U and enrichment of

234U

relative to ²³⁸U by alpha recoil injection. The organic/sulfide complex fraction is depleted in ²³⁰Th compared to ²³⁸U and

234U

. This fact suggests that U was secondarily enriched over Th. As U was enriched at the surface of pyrites, it is inferred that pyrites adsorbed a portion of the eluted U and helped the secondary fixation of U in modern times.

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A new analytical technique for the precise determination of

/²³⁸U isotope ratios was developed for low uranium concentration natural samples by MC-ICPMS to detect their natural isotopic variation. A reproducibility in

234U

/²³⁸U ratio measurements of about 0.18% was obtained from approximately 1.6 ng uranium through the correction of the mass discrimination effect with a reference ²³⁵U/²³⁸U ratio without ²³³U–²³⁶U double spike method. The precision and sample amounts required were improved by more than one order of magnitude compared to those achieved by the conventional alpha spectrometry, and the analysis time of less than 10 minutes per sample was shorter than that of TIMS. The validity of our method was confirmed from a coral reference material JCp-1, with 1.1414±0.0025 and 1.1426±0.0025 as the

234U

/²³⁸U activity ratio, which was consistent with previously reported values. This technique was applied to water samples, and a natural

234U

/²³⁸U isotopic variation was observed in two spring water samples with different redox conditions and groundwater ages. The data obtained in this study demonstrated that this technique will be useful for the hydrological study using

234U

/²³⁸U ratios for samples with small uranium contents including groundwater research.

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Concentrations of

234U

and ²³⁸U in the groundwater samples from Musashino-daichi, western Tokyo have been measured by alpha-spectrometry. Observed range of

234U

and ²³⁸U concentrations were about 0.2-3.5 and 0.3-9.3 dpm/100l, respectively, with the

234U

/²³⁸U activity ratios of 1.4-5.0 The presence of excess

234U

, together with the observed linear correlation with ²³⁸U concentrations, indicates both excess

234U

and²³⁸U have been supplied by source materials which are uniform with respect to the ability of supplying recoilgenic

234U

and ²³⁸U into the groundwaters. High tritium concentrations in many of the samples (Tanaka, 1983) indicate the groundwater samples were composed of two distinct water components: one with fairly long age of contact with U containing minerals (orders of 1000 yrs or more) and one with fairly short tritium age (less than about 30 yrs).

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Advanced maternal age is a risk factor for female infertility, and placental dysfunction is considered one of the causes of pregnancy complications. We investigated the effects of advanced maternal aging on pregnancy outcomes and placental senescence. Female pregnant mice were separated into three groups: young (3 months old), middle (8–9 months old), and aged (11–13 months old). Although the body weights of young and middle dams gradually increased during pregnancy, the body weight of aged dams only increased slightly. The placental weight and resorption rate were significantly higher, and live fetal weights were reduced in a maternal age-dependent manner. Although mRNA expression of senescence regulatory factors (p16 and p21) increased in the spleen of aged dams, mRNA expression of p16 did not change and that of p21 was reduced in the placenta of aged dams. Using a cytokine array of proteins extracted from placental tissues, the expression of various types of senescence-associated secretory phenotype (SASP) factors was decreased in aged dams compared with young and middle dams. The aged maternal placenta showed reduced immune cell accumulation compared with the young placenta. Our present results suggest that models using pregnant mice older than 8 months are more suitable for verifying older human pregnancies. These findings suggest that general cellular senescence programs may not be included in the placenta and that placental functions, including SASP production and immune cell accumulation, gradually decrease in a maternal age-dependent manner, resulting in a higher rate of pregnancy complications.

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A/B-Transferase is a glycosyltransferase that transfers a sugar substrate onto H-antigen, which is responsible for the synthesis of glycoprotein- and glycolipid-conjugates termed A/B-antigens. One polymorphism that causes the ProSer substitution in B-transferase was recently found in a genotyping study, and might be cis-AB. In the present study, we analyzed the phenotypes arising from the enzymatic specificity of B-transferase with the ProSer mutation. To evaluate the effect of the PS mutation on enzymatic specificity, we generated an expression plasmid for B-transferase with ProSer as well as A-transferase with Leu266Met, which is frequently found in cis-ABs. Transfection of B-transferase/PS or A-transferase/L266M cDNA into HeLa cells, an O-blood group cell line, resulted in an AB-phenotype by absorption-elution testing and immunostaining, whereas A- and B-transferase-expressing HeLa cells exhibited only their own activity. Molecular simulation indicated that the PS mutation causes a conformational change in the substrate pocket making it suitable for N-acetylgalactosamine.

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A rapid and simple procedure for the preparation of carrier-free

234Th

for use as a tracer has been devised. A 0.01 mol·dm^-3 HC1 solution (120 cm³) of uranium (1.6 mol·dm^-3) is kept contact with active charcoal. After the bulk uranium solution is removed,

234Th

adsorbed on the charcoal is eluted with a 6 mol·dm^-3 HC1 solution (120 cm³) . A small amount of uranium remaining in the solution of

234Th

is completely removed by passing the solution through anion-exchange column.

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