Grain Refinement by Cyclic Displacive Forward/Reverse Transformation in Fe-High-Ni Alloys

A novel method for grain refinement of martensite structures was proposed, in which transformation strain is accumulated by cyclic displacive forward and reverse transformations. This method can refine martensite structures in an Fe-18Ni alloy because a high density of austenite dislocations is introduced by a displacive reverse transformation in addition to an inheritance of dislocations in body-centered cubic martensite into austenite during cyclic transformation. The addition of a small amount of carbon accelerates structure refinement significantly, which results in the formation of ultra-fine-grained structures after ten cycles.

     

Mining local and tail dependence structures based on pointwise mutual information

The behavior of events that occur infrequently but have a large impact tends to differ from that of the central tendency, and identifying the tail dependence structure among key factors is critical for controlling risks. However, due to technical difficulties, conventional analyses of dependence have focused on the global average dependence. This article proposes a novel approach for analyzing the entire structure of nonlinear dependence between two data sets on the basis of accurate pointwise mutual information estimation. The emphasis is on fat-tailed distributions that tend to appear in events involving sudden large changes. The proposed pointwise mutual information estimator is sufficiently robust and efficient for exploring tail dependence, and its good performance was confirmed in an experimental study. The significance of the identified dependence structure was assessed using the proposed bootstrap procedure. New facts were discovered from its application to daily returns and volume on the New York stock Exchange (NYSE) Composite Index.     

Controlling Pyrene Association in DNA Duplexes by B- to Z-DNA Transitions

B- to Z-DNA transitions play a crucial role in biological systems and have attracted the interest of researchers for their applications in DNA nanotechnology. DNA and DNA analogues have also been used as templates to construct helical chromophore associations with π interactions. In this work, the B- to Z-DNA transition-induced switching of pyrene in an association manner was evaluated using DNA duplexes with non-nucleosidic pyrene residues in the middle of d(CG) repeat sequences. One of the pyrene-labeled DNAs was shown to exhibit inverted exciton coupled circular dichroism signals upon pyrene association through a B- to Z-DNA transition. This observation indicates that pyrene association switches the DNA conformation from right- to left-handed. Interestingly, the fluorescence of the pyrene-labeled DNA duplex also dynamically changed upon switching of the pyrene in an association-based manner. Taken together, these studies demonstrate that pyrene-labeled DNA shows promise as a chiroptical molecular switch.     

Application results of a prototype ultrasonic liquid film sensor to a 7 MPa steam–water two-phase flow experiment

A prototype ultrasonic liquid film sensor was applied to a high-temperature steam–water two-phase flow experiment. The liquid film sensor was vertically installed in a loop which was connected to HUSTLE, a multi-purpose steam source test facility. The hydraulic diameter of the measurement section was 9.4 mm. The output waveforms of the sensor were acquired with a digital oscilloscope. The fluid temperature and system pressure were kept at 288 °C and 7.2 MPa, respectively, during the experiment. The pulse-echo method was used to calculate the liquid film thickness. The cross-correlation calculation was utilized to determine the time difference between the pulse reflected at the sensor surface and the pulse reflected at the liquid film surface. The time-averaged liquid film thicknesses were less than 0.055 mm in the annular flow condition. The increase of the time-averaged thickness was small with the change of the gas momentum flux. The film thicknesses measured with the sensor were compared with the past experimental results; the former were smaller than one-fourth of the thickness estimated as the mean film thickness. The comparison results suggested that the continuous liquid sublayer thickness was measured with the liquid film sensor.     

DNA‐Templated Synthesis of Perylenediimide Stacks Utilizing Abasic Sites as Binding Pockets and Reactive Sites

DNA is considered to be a promising biomolecule as a template and scaffold for arranging and organizing functional molecules on the nanoscale. The construction and evaluation of DNAs containing multiple functional molecules that are useful for optoelectronic devices and sensors has been studied. In this paper we report the efficient incorporation of perylenediimide (PDI) units into DNA by using abasic sites both as binding sites and as reactive sites and the construction of PDI stacks within the DNA structure, accomplished through the preorganization of the PDI units in the hydrophobic pocket within the DNA. Our approach could become a valuable method for construction of DNA/chromophore hybrid structures potentially useful for the design of DNA‐based devices and biosensors.     

Overexpression and purification of Aspergillus aculeatus beta-mannosidase and analysis of the integrated gene in Aspergillus oryzae

An expression plasmid for the manB gene encoding Aspergillus aculeatus beta-d-mannosidase (MANB) was constructed by using an expression vector carrying an improved promoter. After transformation of A. oryzae by the plasmid, several transformants formed colonies emitting fluorescence on a plate containing 4-methylumbelliferyl beta-d-mannopyranoside (MU-Man) under UV-irradiation. The transformant that displayed the strongest fluorescence, named A. oryzae BMN1, produced about 270 mg MANB/l in liquid culture. Recombinant MANB overproduced in BMN1 was purified by two steps of column chromatography to a single protein band on SDS-polyacrylamide gel electrophoresis and had a molecular weight of 130,000. Analyses by Southern blotting and genomic PCR demonstrated that a single copy of the plasmid was integrated into the chromosome by recombination at the niaD locus.     

Occurrence and sources of perfluorinated surfactants in rivers in Japan

We analyzed perfluorinated surfactants (PFSs) in 20 river samples and 5 wastewater secondary effluent samples in Japan to reveal their occurrence and sources. Nine PFS species were determined: perfluorooctanesulfonate (PFOS), perfluorooctane sulfonamide (FOSA), perfluoroheptanoate (PFHpA), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), perfluoroundecanoate (PFUA), perfluorododecanoate (PFDDA), and perfluorotridecanoate (PFTDA). PFSs were detected in all rivers, revealing nationwide contamination of rivers. In particular, 11 out of 20 river samples exceeded New Jersey guidance for PFOA in drinking water (40 ng/L). PFOS, PFHpA, PFOA, and PFNA were major species in Japan. Concentrations of PFOS, PFHpA, and PFNA in rivers were strongly correlated with population density, suggesting that the chemicals were derived from urban activities. PFOA showed a significant but weak correlation. We used crotamiton, a marker of sewage effluent, for further source analysis. Concentrations of PFOS, PFHpA, and PFNAwere strongly correlated with those of crotamiton, and plots of secondary effluents fell near the regression lines of rivers, indicating that the PFOS, PFHpA, and PFNA in rivers were derived from sewage effluent. On the other hand, PFOA was found at remarkably high levels (54-192 ng/L) in seven river samples containing low levels of crotamiton, suggesting that it was derived from nonsewage point sources, as well as sewage effluent. The total fluxes of sewage-derived PFOS, PFHpA, PFOA, and PFNA from Japan were estimated to be 3.6, 2.6, 5.6, and 2.6 t/year, respectively. This is the first report to identify PFOA in several rivers, derived from nonsewage point sources, by using a marker of sewage effluent.     

Estimating Land Use Impacts on Regional Scale Urban Water Balance and Groundwater Recharge

Anthropogenic activities have exerted increasingly large-scale influences on terrestrial ecological systems from the past century, primarily through agriculture; however, the impact of such changes on the hydrologic cycle is poorly understood. As one of the important land use (LU) in the coastal Dogo Plain of the Seto Inland Sea, Japan, paddy fields have been decreasing with the increase in urbanization in recent decades. As the main source of water in the Dogo Plain, groundwater plays an important role in providing people with fresh water and contributing to stream base flow. The purpose of this study is to analyze the water resource and evaluate the effect of LU change on groundwater table fluctuation in this coastal plain. Firstly, the observations of groundwater table and the investigation of water balance were carried out in this alluvial plain. Then, a distributed four-block three-layer water balance model was employed to analyze the groundwater table fluctuation with response to the change of paddy field area. Moreover, the role of paddy field in recharging groundwater in the basin has been clarified. Results show that groundwater table depends not only on rainfall and discharge from rivers, but also on irrigation water and topology of the study area. The net groundwater recharge was positive in irrigation periods whereas that in non-irrigation periods was nearly equal to zero or negative. The results of this study would be helpful to the urban development policy and land use planning decision.     

Microstructure of a Molybdenum Nitride Layer Formed by Nitriding Molybdenum Metal

For pure molybdenum nitrided at 1373 K in NH₃ gas, microstructural observations of a molybdenum nitride layer were conducted through a transmission electron microscope. The molybdenum nitride layer consisted of two molybdenum nitrides: an outer one of γ-Mo₂N and an inner one of β-Mo₂N. A great number of (011)[0     1] type twins were observed in the β-Mo₂N phase, whereas the microstructure of the γ-Mo₂N phase was almost free from lattice defects except for slightly observed {111}〈112〉 type twin.