Dependence of Superconducting Critical Temperature of A15-Type V3Ga on Composition

The composition dependence of the superconducting critical temperature T _c has been investigated for A15-type V₃Ga compounds. The T _c is determined by the specific heat and the magnetic flux transmission ratio through the sample and discussed in terms of the powder X-ray diffraction. The long-range order parameter and the lattice parameter of V₃Ga are evaluated quantitatively by the Rietveld method at each composition, which is evaluated exactly by the electron probe microanalysis (EPMA) measurements. The well-ordered homogeneous alloying structures. V _1–x Ga _x compounds are found to have nearly the same T _c as that for the stoichiometric composition between 0.23<0.25.     

Ho arrangement in the Zn6Mg3Ho icosahedral quasicrystal studied by atomic-resolution Z-contrast STEM

The atomic structure of the Zn6Mg3Ho icosahedral quasicrystal has been studied by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) with Z-contrast (Z: atomic number). We demonstrate that in particular Z-contrast imaging is quite powerful for specifying heavy atom positions in the quasicrystalline compound, as shown by a comparison with high-resolution phase-contrast imaging. It is confirmed that the observed Z-contrast images are fairly well explained by the projected potential of only the Ho atomic arrangement, which was recently proposed by X-ray diffraction analysis; Ho occupies an even-body-center site of the 3-dimensional Penrose lattice. Consequently, the present direct structural observation strongly supports the validity of the proposed Ho site.     

Stability of SrZr0.9Yb0.1O3−α protonic conductor in atmosphere containing nitrogen oxides (NOx)

The stability of the SrZr_0.9Yb_0.1O_3– protonic conductor in an atmosphere containing nitrogen oxides (NO _x ) was investigated. When a fine powder of SrZr_0.9Yb_0.1O_3– with a specific surface area of about 50 m²/g was annealed at 440 °C in He gas containing 8% O₂ and 0.1% NO, the formation of Sr(NO₃)₂ was observed by IR measurement, ion-chromatography analysis and ICP analysis. The formation mechanism of Sr(NO₃)₂ was examined by considering the thermodynamic equilibrium. Based on the results of the thermodynamic calculation, H₂O dissolved into SrZr_0.9Yb_0.1O_3– was estimated to play an important role in the reaction for the formation of Sr(NO₃)₂ between SrZr_0.9Yb_0.1O_3– and NO _x .     

On Active Noise Control Systems With Online Acoustic Feedback Path Modeling

The presence of strong acoustic feedback degrades the convergence speed of the active noise control (ANC) filter, and in the worst case the ANC system may become unstable. A fixed feedback neutralization filter, obtained offline, can be used to neutralize the acoustic feedback. The feedback path, however, may be time varying, and we may need continual adjustments during online operation of the ANC system. This paper proposes a new method for online modeling of the acoustic feedback path in ANC systems. The proposed method uses three adaptive filters; a noise control filter, a feedback path modeling (FBPM) filter, and an adaptive noise cancelation (ADNC) filter. The objective of ADNC filter is to remove the disturbance from the desired response of FBPM filter. In comparison with the existing method, which works only for predictable noise sources, the proposed method can work, as well, with the broadband noise sources. The computer simulations are carried out for narrowband (predictable) (case I) and broadband (random) noise sources (case II). It is demonstrated that the proposed method performs better than the existing method in both cases     

Cover Picture: Assembly and Photoinduced Organization of Mono‐ and Oligopeptide Molecules Containing an Azobenzene Moiety (Adv. Funct. Mater. 9/2007)

An illustration of the phototriggered organization and dispersion of tri‐peptide‐substituted azobenzene derivatives, as reported on p. 1507 by Yoko Matsuzawa and co‐workers. The tri‐peptide units form a beta‐sheet structure through hydrogen bonding to assemble a fibrous network system. Cis–trans photoisomerization of the azobenzene moiety leads to a large polarity change of the component molecule to break and re‐form hydrogen bonds between the tri‐peptide units. Assembled systems consisting of an azobenzene moiety as the photofunctional component and valyl units as the network backbone are investigated. The molecular ordering of these assemblies is examined by spectroscopy and theoretical calculations. The number of valyl units greatly influences the molecular order in the organized systems. Only N‐(L ‐valyl‐L ‐valyl‐L ‐valyl)azobenzene‐4‐carboxamide ( 3 ) forms a complete β‐sheet structure in this artificial assembly. Upon photoirradiation, the azobenzene moieties isomerize completely, revealing the reversibility in the structural organization through the flexibility of the β‐sheet network in this system.     

Pyrrolizidine Alkaloids Mediate Host-Plant Recognition by Ovipositing Females of an Old World Danaid Butterfly, Idea leuconoe

A giant danaid butterfly, Idea leuconoe, specializes on apocynaceous plants such as Parsonsia laevigata, which has been reported to contain pyrrolizidine alkaloids. Females of I. leuconoe deposited eggs in response to methanolic extract of P. laevigata, and subsequent bioassay-guided fractionation of the extract revealed that phytochemicals crucial for host recognition by ovipositing females are Parsonsia-specific macrocyclic pyrrolizidine alkaloids including parsonsianine, parsonsianidine, and 17-methylparsonsianidine. Parsonine, another P. laevigata pyrrolizidine component with a keto-dihydropyrrolizine moiety that is closely related in structure to male pheromones of the butterfly, and several nonhost pyrrolizidine alkaloids were entirely inactive. We interpret these data as strong evidence for an ancestral association through herbivory between danaid butterflies and pyrrolizidine alkaloids.     

The effect of salinity on nitrite accumulation in a down‐flow hanging sponge reactor

BACKGROUND: In this study, the inductive effect of salinity on nitrite accumulation in a down‐flow hanging sponge (DHS) reactor, developed as a novel and cost‐effective wastewater treatment process, was evaluated by conducting a long‐term continuous experiment lasting more than 1400 days. RESULTS: The influent salinity was controlled by adding NaCl at concentrations ranging from 0 to 25 g Cl^? L^?1. The effluent nitrite increased with increases in salinity, i.e. the fraction of nitrite to total nitrogen in the effluent increased from 1.6% at 0 g Cl^? L^?1 to 87.6% at 25 g Cl^? L^?1. Fluorescence in situ hybridization (FISH) analysis revealed that as salinity increased, the nitrifying bacterial community in the DHS changed markedly at the species level. In particular, the dominant nitrite‐oxidizing bacteria changed from Nitrospira‐sublineage I at 0 g Cl^? L^?1 to Nitrobacter spp. at 15 g Cl^? L^?1. At 25 g Cl^? L^?1, no nitrite‐oxidizing bacteria were detected. CONCLUSION: Our findings suggest that the DHS reactor is suitable for cost‐effective nitrite production processes and that salinity control using NaCl is an effective method for inducing nitrite accumulation. Copyright © 2012 Society of Chemical Industry     

Characterization of polystyrene-binding peptides (PS-tags) for site-specific immobilization of proteins

In this study, we characterized polystyrene-binding peptides (PS-tags) that possess a specific binding affinity for hydrophilic polystyrene (phi-PS) plates. Both the FITC-labeled PS19-1 (RAFIASRRIKRP) and PS19-6 (RIIIRRIRR) peptides showed strong binding affinity for commercially available hydrophilic, but not hydrophobic, PS plates in the presence of the non-ionic surfactant Tween 20. The dissociation constants (K_d) of the PS19-1 and PS19-6 peptides for the hydrophilic PS-A plate were 169 and 86 nM, respectively, and the K_d of both peptides increased with the concentration of NaCl or urea. Based on adsorption yield and residual activity of glutathione S-transferase (GST) after fusion with the PS19-6 peptide or its variants, it was found that the basic amino acid in the PS-tags, i.e., Arg was essential for the strong binding affinity of PS-tags in both the peptide and peptide-fused protein forms The aliphatic amino acids in PS19-6 and PS19-6L, such as Ile or Leu, were also effective. Thus, a series of PS-tags that possess this unusual feature, especially the peptides PS19-6 (RIIIRRIRR) and PS19-6L (RLLLRRLRR), are potential candidate affinity peptide tags for site-specific immobilization of proteins onto hydrophilic PS plates, which show potential as solid supports for protein-based biochips.     

Drivability improvement on deep-submicron MOSFETs by elevation ofsource/drain regions

Deep submicron MOSFETs with elevated source/drain (S/D) structures, where S/D extension regions were partially elevated besides deep S/D regions, were fabricated by use of Si selective epitaxial growth technique. As fairly compared with a well-developed conventional MOSFET, we clarify an advantage of the elevated S/D structures, i.e., improvement upon driving performance with keeping excellent short-channel characteristics, which is enhanced for decrease in gate sidewall spacer width. The experimental results are explained in terms of the reduction in S/D parasitic resistance by addition of the Si epitaxial layer where the impurity profile is suitable