Mössbauer study on characterization of Co[Fe(CN)5NH3 \cdot x H2O

The electronic states of Fe atoms in Co[Fe(CN)₅NH₃ H₂O were studied by means of ⁵⁷Fe Mössbauer spectroscopy. The Mössbauer spectra of Co[Fe(CN)₅NH₃ 6H₂O show the coexistence of mixed valences for the Fe atoms and a magnetic relaxation at 4 K. When water molecules were removed, electron transfer from Co to Fe occurred.     

A novel matching network employing surface acoustic wave devices for W-CDMA power amplifiers

This paper describes a new approach of designing high Q surface acoustic wave (SAW) resonators as an inductive element in the matching network for W-CDMA power amplifiers (PAs). Spiral inductors based on CMOS/BiCMOS technologies presently possess relatively low Q (typically <10) and occupy a considerably large area. In order to break through the limitations of the spiral inductors, the authors attempt to apply higher Q and wideband SAW resonators employing Cu-grating/15 degrees YX-LiNbO(3)-substrate structure to the matching network for improved PA performance. An analysis was made on SAW resonators in detail, and an SAW resonator having a very small capacitance ratio of 3.28 and moderate Q of 147.8 was developed. After discussing the frequency dependence of the effective inductances, SAW resonators, which are used to be as inductive elements in the matching networks of PAs, were designed and fabricated. The PA including the matching circuit was simulated using the characteristics of the fabricated SAW resonators. The result showed that with better shape factor and good out-of-rejection, the SAW resonators definitely work as an inductive element and could replace widely used spiral inductors.     

High-speed Photoelastic Stress Analysis of Axially-impacted Finite Column

In an earthquake occurring directly under a city, such as the Hanshin–Awaji great earthquake, the first axial longitudinal impact induced from the source may create fatal damage to the architectural columns. This phenomenon has been confirmed by a theoretical analysis based on elastic wave propagation in columns fixed at both ends. In this paper, the stress intensification behavior in the columns under axial impact is verified by the high-speed photoelastic experiments in combination with semiconductor strain gage and by the theoretical analysis of the longitudinal stress wave analysis method.     

Superlattice-like structure of sputter-deposited amorphous aluminum-heavy element alloys

Al---Zr, Al---Nb, Al---Mo, Al---Ta and Al---W alloys were prepared by DC magnetron sputtering using an Al target with embedded heavy metals disks and substrate rotating around their own central axes and revolving around the central axes of the sputtering chamber. They were examined with X-ray diffraction (XD) of the Cu K, and Al---Ta alloys were also observed by transmission electron microscopy (TEM). Within the diffraction angles, 2τ = 20° ≈ 90°, XD patterns of the examined specimens were all typical of the amorphous structure. However, at the small angle region, 2τ < 10°, a number of sharp diffraction peaks appeared. The lattice spacing obtained from the diffraction peaks was linearly dependent on the inverse of the revolution period of the substrate during the sputter deposition. TEM images showed a layered structure which corresponded to the lattice spacing detected by XD. It is concluded that the superlattice-like structure appearing in the sputter-deposited alloy films arises from the compositional heterogeneity in the sputtered flux of atoms, which comes from the large non-uniformity of the target structure and sputtering conditions.     

Isolation and characterization of thiosalicylic acid selenotrisulfide

Thiosalicylic acid selenotrisulfide(SeT) was prepared by the reaction of thiosalicylic acid and selenious acid in methanol. The precipitated SeT was partially purified by an extensive washing with methanol and pure SeT was isolated by preparative high-performance liquid chromatography (HPLC) using a reverse phase column. The HPLC method was useful both in the analysis and the isolation of SeT.     

Fe-Ni-Zr films with large perpendicular anisotropy deposited on PEN tape by facing targets sputtering

One of the origins of perpendicular magnetic energy of Fe-Zr films may be attributed to the structural inhomogeneity of Fe-rich alloy crystallites in a Fe-Zr amorphous matrix. Fe-Ni-Zr films deposited on PEN tape substrates at about 90°C exhibited large K_u with appropriately large 4πM_s suitable for flexible recording media.     

Investigation of molecular motions of crosslinked polyepichlorohydrin by nuclear magnetic resonance spectroscopy

The molecular motion of crosslinked polyepichlorohydrin (PECH) is studied qualitatively by NMR techniques. The results of temperature dependence of ¹H T₂ and T₁ indicate that the crosslinking (crosslink density < 3%) restricts molecular motions of the polymer even far above its T_g. The ¹H T₁ minimum, corresponding to the large-scale chain-motion of crosslinked PECH, shifts to higher temperatures with increasing crosslink density. ¹H T₂ data also show that the crosslinking hinders free chain motions of the polymer above its T_g. The ¹³C T₁ relaxation time is sensitive to such motional changes as well. ¹³C linewidths of crosslinked PECHs vary with the crosslink density in both the swollen state and the solid state. The mechanism of ¹³C linewidth broadening of crosslinked polymers is discussed in detail. In the case of PECH, the linewidth broadening is caused by changing molecular environment due to crosslinking (such as presence of various chemical shift structures and freezing effects in conformational environment as chain mobility decreases), rather than increasing correlation times, which shorten the relaxation time (T₂) of polymer chains. © 1994 John Wiley & Sons, Inc.     

Self-assemblies of enzymatically degradable amphiphilic oligopeptides as nonviral gene carrier

Novel biodegradable oligopeptide-type gene carriers composed of cationic residues (KRRRKRKRRRKRKRRC) and oligo leucine segments were developed. The amphiphilic carrier was found to form micelle-like assemblies in aqueous solutions, when the oligo leucine is 12 amino acids length (Pep-L12). NMR, CMC, and GPC analysis revealed their hydrophobic/cationic core/shell morphology. Hydrophobic interaction between leucines is thought to be the major driving force behind formations of assemblies. The transient expression of luciferase introduced to COS-1 cells using Pep-L12 below the CMC is as low as that by the control cationic peptides without leucine residue (Pep-L0), while improved transgene expression was observed in the case of Pep-L12 above CMC. The self-assembly raised the apparent molecular weight and gene transfection ability without loosening their low cytotoxicity. These results indicate that the amphiphilic oligopeptides are very promising materials as highly efficient and less toxic gene carriers.