ICTS measurements for p-GaN Schottky contacts

High-temperature isothermal capacitance transient spectroscopy (H-ICTS) measurements were conducted to characterize near mid-gap defects, which are the origin of the memory effect in Ni/p-GaN Schottky contacts. A large single peak was detected only under the forward bias conditions. This indicates that the defects were located in the vicinity of the interface. The change of the peak height and position of the ICTS curves under various bias conditions were qualitatively interpreted by the distribution of the defects and the current flow effect.     

Experimental investigation of amplitude death in delay-coupled double-scroll circuits with randomly time-varying network topology

Nonlinear Dynamics - The present study experimentally investigates amplitude death in delay-coupled double-scroll circuits with a time-varying network topology that randomly changes at a regular...     

Synthesis, crystal structure, and structural conversion of Ni molybdate hydrate NiMoO4·nH2O

The synthesis and crystal structure of NiMoO₄·nH₂O were investigated. The hydrate crystallized in the triclinic system with space group P−1, Z=4 with unit cell parameters of a=6.7791(2) Å, b=6.8900(2) Å, c=9.2486(2) Å, α=76.681(2)°, β=83.960(2)°, γ=74.218(2)°. Its ideal chemical composition was NiMoO₄·3/4H₂O rather than NiMoO₄·1H₂O. Under hydrothermal conditions the hydrate turned directly into α-NiMoO₄ above 483 K, giving nanorods thinner than the crystallites of the mother hydrate. On the other hand, it turned into Anderson type of polyoxomolybdate via a solid-solution process in a molybdate solution at room temperature.     

Measurement of Reflected and Scattered Light for Monitoring Fluctuation of Structures

A laser spectroscopic technique for studying fluctuations of structural objects is presented, together with some results of our investigations including an observation of forced vibration of a refrigerator, intrinsic vibrations of buildings, and appearance of a fluctuation in rotational speed due to fatigue. An alternative detection technique which uses the scattered light for monitoring in place of the mirror-reflected beam is also presented. A leak of water out of a pipeline was detected with this method.

The results obtained with this laser spectroscopic technique should form a useful collection of data regarding fluctuation analysis of various objects.     

Superior Electron‐Transport Ability of π‐Conjugated Redox Molecular Wires Prepared by the Stepwise Coordination Method on a Surface

Electronic conductivity of molecular wires is a critical fundamental issue in molecular electronics. π‐Conjugated redox molecular wires with the superior long‐range electron‐transport ability could be constructed on a gold surface through the stepwise ligand–metal coordination method. The β^d value, indicating the degree of decrease in the electron‐transfer rate constant with distance along the molecular wire between the electrode and the redox active species at the terminal of the wire, were 0.008–0.07 Å^?1 and 0.002–0.004 Å^?1 for molecular wires of bis(terpyridine)iron and bis(terpyridine)cobalt complex oligomers, respectively. The influences on β^d by the chemical structure of molecular wires and the terminal redox units, temperature, electric field, and electrolyte concentration were clarified. The results indicate that facile sequential electron hopping between neighboring metal–complex units within the wire is responsible for the high electron‐transport ability.     

Conformational transition of the core chain in radiation-modified polysilane micelles formed in selective solvents

Poly(methyl acrylate)-grafted poly(methyl-n-propylsilane) (PMPrS-g-PMA) and poly(acrylic acid)-grafted PMPrS (PMPrS-g-PAA) were synthesized by gamma-ray-induced graft polymerization, and the association behavior of these graft copolymers was investigated in selective solvents composed of good and poor solvents for the PMPrS main chain. Fluorescence spectroscopy with perylene as a fluorescent probe revealed that PMPrS-g-PAA in a water/THF mixed solvent self-assembles into micelles with a swollen core of PMPrS chains in the water content range of 50-95%. UV spectroscopy demonstrated that a further increase of the water content gives rise to the conformational transition of the PMPrS chains in the micelle core from the random conformation to the conformation that corresponds to that in the solid state at a water content of ca. 95%, independent of the grafting yield. Similar behavior was also observed in DMSO/THF solutions of PMPrS-g-PMA, for which the conformational transition occurred at the constant DMSO content of ca. 95%. These results indicate that solvatochromic behavior of polysilane, which is a characteristic feature of polysilane, proved to provide information on the inner structure of those micelles: PMPrS chains in the core undergo conformational transition as the content of the poor solvents for PMPrS increases, while maintaining the micelle structure.     

Molecular mass determination of polyamic acid ionic salt by size-exclusion chromatography

A methodology was developed for the determination of molecular weight aveages of polyamic acid ionic salt (PAS) by size-exclusion chromatography (SEC). Polystyrene standards were used for calibration and THF-DMF 1:1 by volume containing 0.06 M LiBr and 0.06 M H3PO4 was used as the mobile phase. The proposed methodology was found to be reproducible.     

A Novel Protoilludane Sesquiterpene from the Wood of Xanthoceras sorbifolia

In the course of our searching for anti-HIV agents from natural sources, we have isolated a triterpene and a doubly linked proanthocyanidin dimer as HIV-1 protease inhibitors from the wood of Xanthoceras sorbifolia Bunge (Sapindaceae)1. Further investigation of this plant has led to the isolation of a protoilludane sesquiterpene (1). The present paper describes the isolation and structural determination of this novel sesquiterpene. The EtOH eluate of a MeOH extract of the wood of X. so…     

Terminal Redox‐Site Effect on the Long‐Range Electron Conduction of Fe(tpy)2 Oligomer Wires on a Gold Electrode

This article completes our comprehensive understanding of the electron transport properties of our original π‐conjugated redox‐active molecular wires comprising Fe bridged by p‐phenylene linkers (tpy=2,2′:6′,2′′‐terpyridine). The Fe(tpy)₂ oligomer wires comprise three types of tpy ligands: the anchor tpy ligand ( A series) makes a junction between the wire and electrode, the bridging bis‐tpy ligand ( L series) connects the Fe(tpy)₂ units, and the terminal tpy ligand ( T series) possesses a redox site as a probe for the long‐range electron transport ability. Taking advantage of the precise tunability of the composition of the Fe(tpy)₂ oligomer wires, thus far we investigated how A and L impacted on the electron‐transport ability. The excellent long‐range electron transport ability with ultrasmall attenuation constants (β^d, 0.002 Å^?1 as the minimum) depends on L significantly [Chem. Asian J. 2009 , 4, 1361], whereas A is unrelated to the β^d value, but influences the zero‐distance electron‐transfer rate constant, k_et⁰ [J. Am. Chem. Soc. 2010 , 132, 4524]. Herein we study the influence of terminal ligand T ^x (x=1–3). β^d is independent of T , however, T³ , with a cyclometallated Ru complex as the redox site, gives rise to a k_et⁰ value greater than T¹ and T² with ferrocene. This series of simple but definitive conclusions indicates that we have reached the stage of being able to precisely design molecular wires to attain desirable single‐molecule electron conduction.     

Antioxidants from rape (Brassica campestris vir. Japonica Hara) oil cake

A simple but novel compound, S-1-methoxy-1-(3,5-dimethoxy-4-hydroxyphenyl)ethane, was isolated as a moderately antioxidative compound from rape (Brassica campestris L. subsp. napus) oil cake together with 5 known compounds. Three of these compounds, indolacetonitrile, 4-hydroxyindolacetonitrile, and 4-hydroxyphenylacetonitrile, showed strong antioxidative activity evaluated by the ferric thiocyanate method.