Low temperature deposited Zr-B film applicable to extremely thin barrier for copper interconnect

We have prepared thin Zr-B films at low temperatures as a new material applicable to an extremely thin barrier against Cu diffusion in Si-ULSI metallization. The obtained Zr-B films mainly consist of the ZrB₂ phase with a nanocrystalline texture on SiO₂ and a fiber texture on Cu. The resistivity of the Zr-B films depends on the substrate of SiO₂ or Cu. The constituent ratio of B/Zr is almost 2, though the contaminants of oxygen, nitrogen, and carbon are incorporated in the film. The nanocrystalline structure of the Zr-B film on SiO₂ is stable due to annealing at temperatures up to 500 °C for 30 min. We applied the 3-nm thick Zr-B film to a diffusion barrier between Cu and SiO₂, and the stable barrier properties were confirmed. We can demonstrate that the thin Zr-B film is a promising candidate for thin film application to a metallization material in Si-ULSIs.     

Exact diagonalization studies on two-band minimal model for iron-based superconductors

In order to explore a superconducting mechanism on iron-based superconductors, we numerically study a two-band minimal model considering two degenerate d_xz and d_yz orbitals on Fe atom. We perform exact diagonalization on a two-band and two-leg square ladder totally composed of 10 lattice sites, which is computationally equivalent to 4-leg 20-sites square-Hubbard-ladder. Consequently, we find that a robust pairing occurs in a wide parameter range when the intra-orbital repulsive interaction becomes smaller than the inter-orbital one. Moreover, the obtained binding energy can grow into much larger value than that obtained in the single band Hubbard model depending on the parameter range.     

A new geranylated aromatic compound from the mushroom Hericium erinaceum

A new geranylated aromatic compound, 5-[(2'E)-3',7'-dimethyl-2',6'-octadienyl]-4-hydroxy-6-methoxy-1-isoindolinone (1), was isolated from the fruiting bodies of the mushroom Hericium erinaceum (Bull.: Fr.) Pers. (Hericiaceae) together with three known sterols, 5alpha,6alpha-epoxy-(22E)-ergosta-8(14),22-diene-3beta,7alpha-diol (2), (22E)-ergosta-7,9(11),22-triene-3beta,5alpha,6beta-triol (3) and (22E)-ergosta-7,22-diene-3beta,5alpha,6alpha,9alpha-tetrol (4). The structure of the new compound was elucidated on the basis of spectral data.     

Heat and mass transfer characteristics of organic sorbent coated on heat transfer surface of a heat exchanger

This paper describes heat and mass transfer characteristics of organic sorbent coated on heat transfer surface of a fin-tube heat exchanger. The experiments in which the moist air was passed into the heat exchanger coated with sorption material were conducted under various conditions of air flow rate (0.5–1.0 m/s) and the temperature of brine (14–20°C) that was the heat transfer fluid to cool the air flow in the dehumidifying process. It is found that the sorption rate of vapor is affected by the air flow rate and the brine temperature. Meanwhile, the attempt of clarifying the sorption mechanism is also conducted. Finally the average mass transfer coefficient of the organic sorbent coated on heat transfer surface of a fin-tube heat exchanger is non-dimensionalzed as a function of Reynolds number and non-dimensional temperature, and it is found that the effect of non-dimensional temperature on them is larger than Reynolds number .     

Studies on the constituents of Catalpa species. VI. Monoterpene glycosides from the fallen leaves of Catalpa ovata G. Don.

Five new monoterpene glycosides, ovatolactone 7-O-(6'-O-p-hydroxybenzoyl)-beta-D-glucopyranoside, ovatic acid methyl ester 7-O-(6'-O-p-hydroxybenzoyl)-beta-D-glucopyranoside, 7-O-p-hydroxybenzoylovatol 1-O-(6'-O-p-hydroxybenzoyl)-beta-D-glucopyranoside, 6'-O-p-hydroxybenzoylcatalposide and (2E,6R)-2,6-dimethyl-8-hydroxy-2-octenoic acid 8-O-[6'-O-(E)-p-coumaroyl]-beta-D-glucopyranoside were isolated from the fallen leaves of Catalpa ovata G. Don. Their structures were determined by extensive spectroscopic studies and syntheses.     

The role of vibrational temperature variations in a pulsed dielectric barrier discharge plasma device

The use of dielectric barrier discharge (DBD) plasmas has become a practical way to carry out surface treatment where precise control of the plasma parameters, such as rotational and vibrational temperatures (T_rot and T_vib), is required. As the T_vib of an atmospheric pressure plasma jet appears to be the most important parameter related to the improvement of surface treatments, in this work, we analysed two methods to increase the values of T_vib in a DBD plasma jet device. One of the methods is to reduce the exit size (ø) of the DBD reactor, which results in an increase in the measured T_vib values, due to an increase in the pressure inside the reactor. The other method is to change the gas flow rate (GFR) used to produce the plasma jets. This leads to a T_vib reduction when the GFR is increased in the case of using helium or nitrogen as the working gas, but the opposite happens (an increase in the T_vib values) when argon is used, with different phenomena causing the variation of T_vib in each situation.