Microcrystals of coesite and stishovite were discovered as inclusions in amorphous silica grains in shocked melt pockets of a lunar meteorite Asuka-881757 by micro-Raman spectrometry, scanning ...electron microscopy, electron back-scatter diffraction, and transmission electron microscopy. These high-pressure polymorphs of SiO₂ in amorphous silica indicate that the meteorite experienced an equilibrium shock-pressure of at least 8–30 GPa. Secondary quartz grains are also observed in separate amorphous silica grains in the meteorite. The estimated age reported by the ³⁹Ar/⁴⁰Ar chronology indicates that the source basalt of this meteorite was impacted at 3,800 Ma ago, time of lunar cataclysm; i.e., the heavy bombardment in the lunar surface. Observation of coesite and stishovite formed in the lunar breccias suggests that high-pressure impact metamorphism and formation of high-pressure minerals are common phenomena in brecciated lunar surface altered by the heavy meteoritic bombardment.
A simple method is proposed for achieving short-range multiple-input multiple-output (MIMO) transmission without complicated signal processing. This is achieved by a spatial division that cancels ...interference between signal streams by using π-phase-shifted antenna directivities in high speed parallel transmission systems at 60 GHz. The method achieves spatial division transmission without MIMO detection even for antenna elements with wide beamwidths. This makes it easy to design antenna elements and reduces signal processing costs in the transmitter and the receiver. Moreover, the method provides almost the same channel capacity as that of the complicated MIMO transmission methods. The optimal antenna array length is derived to maximise the capacity and the validity of the proposed method is confirmed through numerical and experimental analyses at 4.85 GHz.
The purpose of this study was to better understand the metallurgical transformations that occur during heat treatment of Nd-based magnets. DSC analysis and microstructural investigations of the grain ...boundaries with SEM and TEM were carried out. DSC permitted to optimize the heat treatment. Microstructural investigations always showed the presence of thin and smooth RE-rich film, associated with the highest coercivity. copyright 2002 Elsevier Science B.V. All rights reserved.
The 440 amino acid Mtu
recA intein consists of independent protein-splicing and endonuclease domains. Previously, removal of the central endonuclease domain of the intein, and selection for function, ...generated a 168 residue mini-intein, ΔI-SM, that had splicing activity similar to that of the full-length, wild-type protein. A D422G mutation (ΔI-CM) increased C-terminal cleavage activity. Using the ΔI-SM mini-intein structure (presented here) as a guide, we previously generated a highly active 139 residue mini-intein, ΔΔI
hh-SM, by replacing 36 amino acid residues in the residual endonuclease loop with a seven-residue β-turn from the autoprocessing domain of Hedgehog protein. The three-dimensional structures of ΔI-SM, ΔΔI
hh-SM, and two variants, ΔΔI
hh-CM and ΔΔI
hh, have been determined to evaluate the effects of the minimization on intein integrity and to investigate the structural and functional consequences of the D422G mutation. These structural studies show that Asp422 is capable of interacting with both the N and C termini. These interactions are lacking in the CM variant, but are replaced by contacts with water molecules. Accordingly, additional mutagenesis of residue 422, combined with mutations that isolate N-terminal and C-terminal cleavage, showed that the side-chain of Asp422 plays a role in both N and C-terminal cleavage, thereby suggesting that this highly conserved residue regulates the balance between the two reactions.
We used reflectance difference spectroscopy (RDS) and surface differential reflectance spectroscopy (SDRS) to investigate the molecular orientation of ultrathin α-sexithiophene (α-6T) films on four ...passivated Si(100)-(2×1) surfaces, oxidized Si(001), water-adsorbed Si(001), hydrogen-adsorbed Si(001) and ethylene-adsorbed Si(001), in order to study the substrate dependence of the molecular orientation of isolated molecules and molecules located in islands or films. Strong in-plane anisotropy was observed on ethylene-adsorbed Si(001) even at 5nm film thickness, which was not the case for the other substrates.
•Orientation of the α-sexithiophene molecules grown on passivated silicon surfaces•Characterization of organic thin films using reflectance spectroscopic methods•In situ real-time monitoring of the growth process of organic thin films
We analysed the effect of three antioxidants that have different functional mechanisms on the in vitro maturation (IVM) of porcine oocytes. Single oocyte monoculture using the hanging drop (HD) ...system has some advantages such as improving analysis efficiency brought by the smaller number of samples than the number of oocytes cultured in one drop. Direct effects of ligands on single oocytes could also be detected without considering the effects of paracrine factors from other oocytes. After 22 h of pre‐culture, denuded oocytes were cultured for 22 h with 0.01 and 0.1 μg/ml of L‐carnitine (LC), lactoferrin (LF) or sulforaphane (SF) in the presence/non‐presence of oxidant stress induced by H₂O₂ supplementation to evaluate the reducing effects against oxidative stress on nuclear maturation. As a result, compared with LC and SF, LF showed effective reduction in oxidative stress at a lower concentration (0.01 μg/ml), suggesting that LF is a more effective antioxidant in porcine oocyte IVM. Additionally, LF also increased maturation rate even in culture without H₂O₂. Our results clearly suggest that the HD monoculture system is useful for screening the substances that affect porcine oocyte culture.
High-strain-rate superplasticity describes the ability of a material to sustain large plastic deformation in tension at high strain rates of the order of 10-2 to 10-1 s-1 and is of great ...technological interest for the shape-forming of engineering materials. High-strain-rate superplasticity has been observed in aluminium-based and magnesium-based alloys. But for ceramic materials, superplastic deformation has been restricted to low strain rates of the order of 10-5 to 10-4 s-1 for most oxides and nitrides with the presence of intergranular cavities leading to premature failure. Here we show that a composite ceramic material consisting of tetragonal zirconium oxide, magnesium aluminate spinel and α-alumina phases exhibits superplasticity at strain rates up to 1 s-1. The composite also exhibits a large tensile elongation, exceeding 1,050 per cent for a strain rate of 0.4 s-1. The tensile flow behaviour and deformed microstructure of the material indicate that superplasticity is due to a combination of limited grain growth in the constitutive phases and the intervention of dislocation-induced plasticity in the zirconium oxide phase. We suggest that the present results hold promise for the application of shape-forming technologies to ceramic materials.
A simpler MIMO transmission method using orthogonal directivities is proposed. In future wireless communication systems, higher data rates will be required since large amounts of data will be ...transmitted and received. MIMO technology is useful for achieving higher data rates. However, since MIMO detection becomes complicated when the number of antennas becomes large, a simpler method should be considered. To solve this problem, the present authors proposed a spatial division method using orthogonal directivities. This previously proposed method to N streams is expanded transmission for application to much higher data rate systems. Furthermore, using higher order antenna modes at the same frequency to more easily obtain orthogonal directivities is proposed. To evaluate the proposed method, it is confirmed by numerical analysis that the capacity of the proposed method increases without MIMO detection when the number of antennas becomes large.
▶ High pressure spark plasma sintering (SPS) is applied to prepare transparent yttria-stabilized zirconia (YSZ). ▶ The resultant YSZ exhibit good in-line transmittance and maintain nano-grained ...microstructure.
We show an optimum condition for high-pressure (400
MPa) spark-plasma-sintering (SPS) of transparent cubic (8
mol% yttria) zirconia. The obtained samples represent higher in-line transmittance compared to the existing SPSed zirconias, and maintain nano-grained structures. The role of oxygen defects in transparency of the zirconia is discussed.
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