Flux-Line Entanglement as the Mechanism of FLL-Melting Transition in Anisotropic HTSC

The mechanism of the flux-line-lattice (FLL) melting in anisotropic high-T _c superconductors in B is clarified by Monte Carlo simulations of the 3D frustrated XY model. The percentage of entangled flux lines abruptly changes at the melting temperature T _m , while no sharp change can be found in the number and size distribution of vortex loops around T _m . Therefore, the origin of this melting transition is the entanglement of flux lines. Scaling behaviors of the melting temperature T _m are consistent with this one-dimensional character of the entanglement mechanism of the FLL melting. That is, T _m does not depend on the system size in the ab plane, while it is scaled by the system size along the c axis, L _c , as T _m(L _c ) – T _m() L _c ^-d , d = 1.     

In situ Observation of the Growth of Ribbon-like Thin Films of Bi-2212 on an Ag Substrate

We have developed a simple technique to grow ribbon-like single crystalline films of Bi- 2212 on Ag substrates. The process is performed under ambient pressure only by heating a Bi-2212 pellet on the edge of the substrates. ¹ The ribbon-like films thus grown showed sharp superconducting transitions with an onset temperature of 80K. The formation of the ribbons was studied by observing their growth with a high- temperature microscope. In situ observation with the microscope revealed that most of the ribbon crystals grew during the 10 minutes of the plateau at 905° C. In particular, the early part of the plateau was the dominant stage of growth.     

Direct observation of local atomic order in a metallic glass

The determination of the atomic configuration of metallic glasses is a long-standing problem in materials science and solid-state physics. So far, only average structural information derived from diffraction and spectroscopic methods has been obtained. Although various atomic models have been proposed in the past fifty years, a direct observation of the local atomic structure in disordered materials has not been achieved. Here we report local atomic configurations of a metallic glass investigated by nanobeam electron diffraction combined with ab initio molecular dynamics simulation. Distinct diffraction patterns from individual atomic clusters and their assemblies, which have been theoretically predicted as short- and medium-range order, can be experimentally observed. This study provides compelling evidence of the local atomic order in the disordered material and has important implications in understanding the atomic mechanisms of metallic-glass formation and properties.     

Synthesis of 3,4‐Fused 2‐Quinolones from an (ortho‐Aminophenyl)propiolate via Sequential Cycloaddition/Lactam Formation

An N‐phthalimide‐protected (ortho‐aminophenyl)propiolate was prepared by the carboxylation of the corresponding silylalkyne precursor with carbon dioxide. The obtained propiolate was further transformed to various 3,4‐fused 2‐quinolones via cycloadditions and subsequent deprotection/lactam formation.

     

Pesticide adsorption by granular activated carbon adsorbers. 2. Effects of pesticide and natural organic matter characteristics on pesticide breakthrough curves

The principal objective of this study was to elucidate mechanisms by which NOM affects the adsorption of a nonpolar (simazine) and a polar (asulam) herbicide on activated carbon. Experiments were carried out in microcolumns that were continuously fed solutions containing NOM with different molecular weight (MW) distributions and intermittently solutions containing the same NOM plus simazine or asulam. The MW distributions of a groundwater NOM were altered by coagulation and ultrafiltration, which resulted in the preferential removal of high-MW, UV260-absorbing NOM. At a given NOM loading, the simazine removal efficiency was higher in the column that was preloaded with raw groundwater than in columns receiving coagulated or ultrafiltered water. In contrast, the asulam removal efficiency was similar for all three NOM solutions at a given NOM loading. Therefore, the results suggested that low-MW, UV260-absorbing NOM molecules competed directly with strongly adsorbing pesticides, such as simazine, for adsorption sites. For more weakly adsorbing pesticides, such as asulam, direct competition for adsorption sites originated not only from the strongly adsorbing, low-MW NOM, but also from more weakly adsorbing, higher-MW NOM. Consequently, the competing NOM fraction increases as the adsorbability of the SOC decreases, a result that was confirmed by adsorption data for additional pesticides of similar size. However, a smaller pesticide competed more effectively for adsorption sites than a larger pesticide of similar polarity, suggesting that the concentration of competing NOM decreases as the MW of the SOC decreases.     

Ultra-high-density interconnection technology of three-dimensional packaging

The study of 20-μm-pitch interconnection technology of three-dimensional (3D) packaging focused on reliability, ultrasonic flip–chip bonding and Cu bump bonding is described. The interconnection life under a temperature cycling test (TCT) was at an acceptable level for semiconductor packages. Failure analysis and finite element analysis revealed the effect of material properties. Basic studies on ultrasonic flip–chip bonding and very small Cu bump formation were investigated for low-stress bonding methods. The accuracy of ultrasonic flip–chip bonding was almost the same level as that of thermocompression bonding and the electrical connection was also confirmed. Atomic-level bonding was established at the interface of Au bumps. For Cu bump bonding, a dry process was applied for under bump metallurgy (UBM) removal. Electroless Sn diffusion in Cu was investigated and the results clarified that the intermetallic layer was formed just after plating. Finally, we succeeded in building a stacked chip sample with 20-μm-pitch interconnections.     

Variational method for super-resolution optical flow

The motion fields in an image sequence observed by a car-mounted imaging system depend on the positions in the imaging plane. Since the motion displacements in the regions close to the camera centre are small, for accurate optical flow computation in this region, we are required to use super-resolution of optical flow fields. We develop an algorithm for super-resolution optical flow computation. Super-resolution of images is a technique for recovering a high-resolution image from a low-resolution image and/or image sequence. Optical flow is the appearance motion of points on the image. Therefore, super-resolution optical flow computation yields the appearance motion of each point on the high-resolution image from a sequence of low-resolution images. We combine variational super-resolution and variational optical flow computation in super-resolution optical flow computation. Our method directly computes the gradient and spatial difference of high-resolution images from those of low-resolution images, without computing any high-resolution images used as intermediate data for the computation of optical flow vectors of the high-resolution image.     

Transverse crack growth behavior considering free-edge effect in quasi-isotropic CFRP laminates under high-cycle fatigue loading

The high-cycle fatigue characteristics focused on the behavior of the transverse crack growth up to 10⁸ cycles were investigated using quasi-isotropic carbon fiber reinforced plastic (CFRP) laminates whose stacking sequence was [−45/0/45/90]_s. To assess the fatigue behavior in the high-cycle region, fatigue tests were conducted at a frequency of 100 Hz in addition to 5 Hz. In this study, to evaluate quantitative characteristics of the transverse crack growth in the high-cycle region, the energy release rate considering the free-edge effect was calculated. Transverse crack growth behavior was evaluated based on a modified Paris law approach. The results revealed that transverse crack growth was delayed under the test conditions of the applied stress level of σ_max/σ_b = 0.2.     

Anomalous flux pinning of UPd2Al3

The ac magnetic susceptibility of UPd₂Al₃ in the superconducting state has been measured to test of the existence of the Fulde, Ferrell, Larkin and Ovchinnikov (FFLO) state. A dip in the susceptibility has been observed in the vicinity of the upper critical field and the temperature range from zero to T_c. This dip is very sensitive to the amplitude of the ac magnetic field. The anomaly is explained by the increase of the flux pinning effect. Recent theories suggest that the pinning force becomes stronger in the FFLO state, and the existence of the nonuniform state due to the order parameter mixing in a d-wave superconductor is possible near T_c.     

Xylanase from Marine Filamentous Fungus Pestalotiopsis sp. AN-7 Was Activated with Diluted Salt Solution Like Brackish Water

The genus Pestalotiopsis are endophytic fungi that have recently been identified as cellulolytic system producers. We herein cloned a gene coding for a xylanase belonging to glycoside hydrolase (GH) family 10 (PesXyn10A) from Pestalotiopsis sp. AN-7, which was isolated from the soil of a mangrove forest. This protein was heterologously expressed by Pichia pastoris as a host, and its enzymatic properties were characterized. PesXyn10A was produced as a glycosylated protein and coincident to theoretical molecular weight (35.3 kDa) after deglycosylation by peptide-NfF-glycosidase F. Purified recombinant PesXyn10A exhibited maximal activity at pH 6.0 and 50 °C, and activity was maintained at 90 % at pH 5.0 and temperatures lower than 30 °C for 24 h. The substrate specificity of PesXyn10A was limited and it hydrolyzed glucuronoxylan and arabinoxylan, but not β-glucan. The final hydrolysis products from birchwood xylan were xylose, xylobiose, and 1,2³-α-D-(4-O-methyl-glucuronyl)-1,4-β-D-xylotriose. The addition of metallic salts (NaCl, KCl, MgCl₂, and CaCl₂) activated PesXyn10A for xylan degradation, and maximal activation by these divalent cations was approximately 160 % at a concentration of 5 mM. The thermostability of PesXyn10A significantly increased in the presence of 50 mM NaCl or 5 mM MgCl₂. The present results suggest that the presence of metallic salts at a low concentration, similar to brackish water, exerts positive effects on the enzyme activity and thermal stability of PesXyn10A.