Characterization and electrochemical properties of CF4 plasma-treated boron-doped diamond surfaces

The effect of CF₄ plasma etching on diamond surfaces, with respect to treatment time, was investigated using scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. SEM observations and Raman spectra indicated an increase in surface roughening on a scale of 10–20 nm, and an increase in crystal defect density was apparent with treatment time in the range of 10 s to 30 min. In contrast, alteration of the diamond surface terminations from oxygen to fluorine was found to be rather rapid, with saturation of the F/C atomic ratio estimated from XPS analysis after treatment durations of 1 min and more. The redox kinetics of Fe(CN)₆^3−/4− was also found to be significantly modified after 10 s of CF₄ plasma treatment. This behavior shows that C–F terminations predominantly affect the redox kinetics compared to the effect on the surface roughness and crystal defects. The double-layer capacitance (C_dl) of the electrolyte/CF₄ plasma-treated boron-doped diamond interface was found to show a minimum value at 1 min of treatment. These results indicate that a short-duration CF₄ plasma treatment is effective for the fabrication of fluorine-terminated diamond surfaces without undesirable surface damage.     

Study on shock wave and turbulent boundary layer interactions in a square duct at Mach 2 and 4

In this paper, the outline of the Mach 4 supersonic wind tunnel for the investigation of the supersonic internal flows in ducts was firstly described. Secondly, the location, structure and characteristics of the Mach 2 and Mach 4 pseudo-shock waves in a square duct were investigated by color schlieren photographs and duct wall pressure fluctuation measurements. Finally, the wall shear stress distributions on the side, top and bottom walls of the square duct with the Mach 4 pseudo-shock wave were investigated qualitatively by the shear stress-sensitive liquid crystal visualization method. The side wall boundary layer separation region under the first shock is narrow near the top wall, while the side wall boundary layer separation region under the first shock is very wide near the bottom wall.     

Serial Changes of Serum Growth Factor Levels and Liver Regeneration after Partial Hepatectomy in Healthy Humans

This study aimed to investigate the associations of the serial changes of serum levels of various growth factors with liver regeneration after hepatectomy in healthy liver donors. Sixteen healthy liver donors who underwent conventional liver resection were included. Serum levels of various growth factors before hepatectomy and on postoperative day (POD) 1, 3, 5 and 7 were measured. Liver volume data calculated by multi-detector computed tomography using workstation. The ratio of remnant liver volume on POD 0 to liver volume before the operation was 51% ± 20%. The ratio of liver volume on POD 14 to liver volume on POD 0 were inversely correlated with remnant liver volume on POD 0 (r = −0.91). The ratio of liver volume on POD 14 to liver volume on POD 0 were significantly correlated with serum hepatocyte growth factor (HGF) levels on POD 1 (r = 0.54), serum leptin levels on POD 1 (r = 0.54), and serum macrophage colony-stimulating factor (M-CSF) levels on POD 5 (r = 0.76) and POD 7 (r = 0.80). These results suggest that early-phase elevation of serum levels of HGF, leptin and M-CSF may be associated with the acceleration of liver regeneration after hepatectomy in humans.     

Purification and characterization of a novel glutamyl aminopeptidase from chicken meat

A novel glutamyl aminopeptidase (aminopeptidase A, EC 3.4.11.7) was purified from chicken meat by ammonium sulfate fractionation, ethanol fractionation, heat treatment, and successive column chromatographies of DEAE-Sepharose CL-6B and Sephadex G-200. The purified enzyme migrated as a single band on SDS-PAGE. The molecular weight of this enzyme was found to be 55,000 and 550,000 by SDS-PAGE and Sephadex G-200 column chromatographies, respectively. This enzyme hydrolyzed Glu- and Asp-, but not Leu-, Arg-, and Ala-2-naphthylamide (-2NA) at all. The optimum pH and temperature for hydrolysis of Glu-2NA was 7.5. and 70°C, respectively. Reducing agents such as cysteine and dithiothreitol inhibited the activity of this enzyme at concentrations of 1 mM. However, the activation by Ca(2+) and the inhibition by amastatin were not observed.     

Nonlinear adaptive control system design and experiment for a 3-DOF model helicopter

This paper deals with model following control of a model helicopter with three degree-of-freedom. Since the decoupling matrix is singular, a nonlinear structure algorithm is used to design the controller. Furthermore, since the model dynamics are described linearly by unknown system parameters, a well-known parameter estimation technique is introduced. The integral type of estimation model is proposed here since the use of the derivative type of model cannot obtain the desired estimation result. The experimental results show the effectiveness of the proposed method. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Numerical assessment of the seismic response of an earth embankment on liquefiable soils

This study presents a numerical assessment of the seismic behaviour of an earth embankment founded on liquefiable foundation soils during earthquake loading. Analysis was carried out using an effective stress-based, fully coupled, finite element method. The behaviour of the sandy soil is described by means of a cyclic elastoplastic constitutive model which was developed within the framework of the Armstrong–Frederick type non-linear kinematic hardening concept. The numerical method and the analysis procedure are briefly outlined and as an example, the seismic response of an earth embankment on a saturated sand foundation is assessed. Based on the numerical results, the distinctive patterns of seismic response of the embankment are discussed. Special emphasis is given to the computed results of excess pore water pressures, co-seismic and post-seismic deformations, and accelerations during the seismic excitation. It has been found that the numerical model can capture fundamental liquefaction aspects of the embankment foundation system and produce preliminary results for its seismic assessment.      

Technique for characterizing single-mode operability in optical fibers by utilizing variable-aperture technique

We propose a technique, new to our knowledge, for characterizing single-mode operability by monitoring far-field patterns via a variable aperture. We clarify the applicability of our proposed technique to cutoff wavelength measurement, which agrees well with cutoff wavelength obtained by a conventional multimode reference technique. We also show the applicability of our proposed technique to holey fibers including photonic crystal fibers (PCFs) with uniform air-hole structure and effectively W-shaped air-hole structure. We can clearly characterize the single-mode operability of the PCF. The bend dependence of the single-mode bandwidth is also revealed by utilizing our proposed technique.     

Cloning and characterization of a β-N-acetylglucosaminidase (BmFDL) from silkworm Bombyx mori

In insects, β-N-acetylglucosaminidase (GlcNAcase) participates in critical physiological processes such as fertilization, metamorphosis, and glycoconjugate degradation. Insects produce glycoproteins carrying paucimannosidic-type N-glycans, the terminal GlcNAc residue of which is cleaved by a GlcNAc-linkage specific GlcNAcase, also known as the fused lobes (FDL) protein. To obtain information on the structure of GlcNAcases and insight into their contribution to physiological processes, we cloned Bombyx mori FDL (BmFDL) from silkworm larvae. The full-length cDNA (1.9 kb) encoded a protein of 633 amino acids with 42% amino acid sequence identity to Drosophila melanogaster FDL (DmFDL). Recombinant BmFDL cleaved only β-1,2-linked GlcNAc residues from the α-1,3 branch of biantennary N-glycan. This substrate specificity was similar to that of DmFDL. Microsomal FDL activity was inhibited by anti-BmFDL antibodies. Taken together, our results suggest that BmFDL is a N-glycan-processing GlcNAcase in B. mori.     

Improvement of characteristics of new-type solar cells, having a “transparent conductor/thin Si02 layer with ultrafine metal particles as conductive channels/n-Si” junction

New-type solar cells, having a structure “transparent conductor/thin Si0₂ layer with ultrafine metal islands as conductive channels/n-Si” have been prepared by forming a very thin (< 1.0 nm) silicon oxide (Si0₂) layer as well as platinum (Pt) islands (5–50 nm in size) embedded in it on a single crystal n-type silicon (n-Si) wafer, followed by the deposition of an indium tin oxide (ITO) film (200 nm thick) by the electron-beam evaporation method. The open-circuit photovoltages (V_oc) of the solar cells of the above structure were relatively low, 0.25–0.47 V, but they increased very much to 0.50–0.59 V if a thin (3–10 nm) layer of an organic compound such as copper phthalocyanine (CuPc) was pre-deposited on the Pt-island modified n-Si wafer before the ITO deposition. The reason for the beneficial effect of the pre-deposition of the thin CuPc layer was investigated in detail, and it has been found that certain crystal defects are formed in n-Si near the n-Si/Si0₂ interface during the ITO deposition in the absence of the CuPc layer. The formation of such defects is prevented in the presence of the CuPc layer, which leads to a decrease in surface carrier recombination and hence to the increase in V_oc.     

Analysis of Transglucosylation Products of Aspergillus niger α-Glucosidase that Catalyzes the Formation of α-1,2- and α-1,3-Linked Oligosaccharides

According to whole-genome sequencing, Aspergillus niger produces multiple enzymes of glycoside hydrolases (GH) 31. Here we focus on a GH31 α-glucosidase, AgdB, from A. niger . AgdB has also previously been reported as being expressed in the yeast species, Pichia pastoris ; while the recombinant enzyme (rAgdB) has been shown to catalyze tranglycosylation via a complex mechanism. We constructed an expression system for A. niger AgdB using Aspergillus nidulans . To better elucidate the complicated mechanism employed by AgdB for transglucosylation, we also established a method to quantify glucosidic linkages in the transglucosylation products using 2D NMR spectroscopy. Results from the enzyme activity analysis indicated that the optimum temperature was 65 °C and optimum pH range was 6.0–7.0. Further, the NMR results showed that when maltose or maltopentaose served as the substrate, α-1,2-, α-1,3-, and small amount of α-1,1-β-linked oligosaccharides are present throughout the transglucosylation products of AgdB. These results suggest that AgdB is an α-glucosidase that serves as a transglucosylase capable of effectively producing oligosaccharides with α-1,2-, α-1,3-glucosidic linkages.