Relations between the Ruderman-Kittel-Kasuya-Yosida interaction electron concentration and crystal structure

The Ruderman-Kittel-Kasuya-Yosida interaction between localized magnetic spins on the basis of perfectly free conduction electron is calculated as a function of the Fermi wave vector of the conduction electrons. The expression of the interaction according to us converges rapidly, furthermore is strongly related to the detailed crystal structure. The q-dependence of exchange interaction j(q) between conduction- and localized magnetic electron is also taken into account. The result of the calculation is compared successfully with the change of magnetic structures, with θ_p and T_c or T_N of compounds having the CsCl structure, but less successfully with gadolinium compounds having the NaCl structure. These facts are discussed in conjunction with the difference of the RKKY interaction in the cscl and the NaCl structure.     

Inhibition of experimental pulmonary metastasis of Lewis lung carcinoma by orally administered beta-glucan in mice

The inhibitory effect on experimental pulmonary metastasis of Lewis lung carcinoma (3LL) of SSG, a (1----3)-beta-D-glucan obtained from the fungus Sclerotinia sclerotiorum IFO 9395, administered orally was examined in mice. Oral administration of SSG for 10 consecutive days just after the intravenous implantation of tumor cells significantly inhibited the experimental pulmonary metastasis of 3LL at a dose of 2000 micrograms. However, SSG administered orally involving other timings was less effective. In comparison with oral administration, SSG was effective when administered intraperitoneally for 10 consecutive days at a dose of 200 micrograms. These results suggest that SSG given by both parenteral and nonparenteral routes is effective in the inhibition of experimental pulmonary metastasis of tumors.     

Schizophyllans carrying oligosaccharide appendages as potential candidates for cell-targeted antisense carrier

Schizophyllans carrying beta-lactoside and alpha-mannoside appendages were prepared from native schizophyllan through NaIO4 oxidation followed by reductive amination using aminoethyl-beta-lactoside and alpha-mannoside, respectively. The resulting schizophyllans form stable macromolecular complexes with polynucleotides, such as poly(C) and poly(dA). Specific affinity between these macromolecular complexes and saccharide-binding proteins was demonstrated by surface plasmon resonance and agarose gel staining assays. beta-lactoside-appended schizophyllan enhanced an antisense activity in hepatocytes which express lactoside-binding proteins on their cell surfaces.     

Molecular-length and chiral discriminations by beta-structural poly(L-alanine) on silica

Poly(L-alanine)-grafted porous silica (Sil-Ala22) was prepared by polymerization of N-carboxyanhydride of L-alanine initiated by 3-aminopropylated silica. Its selective interaction with aromatic guest molecules was evaluated by the retention time in liquid chromatography using the column packed with Sil-Ala22. Sil-Ala22 showed a specific selective retention with discriminating molecular shapes, such as molecular length, linearity and planarity. This selectivity can be explained by a multiple pi-pi interaction with the carbonyl groups one dimensionally-aligned on the rigid beta-form structure in the peptide main chain. Chiral separation with Sil-Ala22 was also described.     

New aspects of light emission from STM

The recently discovered new mechanism of light emission from a scanning tunneling microscope (STM) compared with well-known conventional mechanisms is reviewed. The new mechanism was found for nanoscale structures which are composed of silicon (Si) dangling bonds on Si(001) surfaces. When an STM tip made of tungsten is located above Si dangling bond sites, visible light is emitted at a quantum efficiency of the order of 10^-6 photons/electron. Light is generated by radiative dipole transitions between the surface state of the tip and that of the sample. In the visible-light emission, optical selection rules still apply. The linear polarization of isochromat light emitted from the tunneling gap between an STM tip and a Si(001) sample strongly depends on the bias voltage between the tip and the sample. The results show that the ^* and ^* surface states of the sample contribute to the emission of p-polarized and s-polarized light, respectively, in accordance with optical selection rules. PACS 07.79.-v; 73.20.-r     

Diastereoselective addition of alcohol to diastereotopic silylenes

The successful example of diastereoselective addition of alcohol to diastereotopic silylenes is reported.     

Determination of Compounds Inhibiting Bacterial Growth in Sterilized Medical Devices

Summary Medical devices must be sterilized before shipping. During sterilization the quality of the medical device must be maintained. Polysulfone (PS) and polycarbonate (PC) are often used as materials for medical devices. It has been observed that compounds inhibiting bacterial growth are produced when PS or PC are sterilized by autoclaving or by use of ozone gas, especially when ozone gas is used to sterilize PS. This study was conducted to identify the compounds inhibiting bacterial growth. An ethanol extract of the sterilized PS or PC was analyzed by liquid chromatography–mass spectrometry–UV photodiode array (210–350nm) for identification and determination of the inhibitors. Bisphenol A, 4,4-dihydroxydiphenyl sulfone (bisphenol S), and 4-chloro-4-hydroxydiphenyl sulfone were identified in PS sterilized with ozone gas. Bisphenol A was also identified in PC sterilized with ozone gas. Bisphenol A was not a major inhibitor of bacterial growth because the extent of inhibition did not correlate with the amount of bisphenol A produced. Inhibition by 4-chloro-4-hydroxydiphenyl sulfone was greater than by bisphenol S and correlated with the amount produced; the major inhibitor might therefore be 4-chloro-4-hydroxydiphenyl sulfone. The combined effect of bisphenol S and 4-chloro-4-hydroxydiphenyl sulfone might be a more realistic measure of the exact amount of inhibition.     

Mechanism of characteristic shape of resistive transition in Bi2Sr2CaCu2O8 films made by laser evaporation

We measured the temperature dependence of resistivity, (T, H), of Bi₂Sr₂CaCu₂O₈ thin films in magnetic fields. These films have a preferential orientation of the c-axis perpendicular to a surface of the substrate. We could not observe any meaningful anisotropy of the characteristic shape of the resistive transition between two cases of the current flow parallel and perpendicular to the magnetic field in the basal plane. Therefore, it is very difficult to ascribe the broadness to any origin due to the Lorentz force produced by an external current.     

Electrospray ionization mass spectra of hemoglobin and transferrin by a magnetic sector mass spectrometer. Comparison with theoretical isotopic distributions.

Electrospray ionization mass spectra of human hemoglobin chains and of transferrin were acquired on a magnetic sector mass spectrometer. The observed molecular ion for each hemoglobin chain was in good agreement with the theoretical isotopic distribution at a reasonable resolution of 2000. The clear separation of a variant beta-chain in admixture with the normal counterpart at mass 15,867 that differed from it by 14 Da (0.09%) ensured that a smaller mass difference could be detected. The molecular ions for human transferrin were too broad compared with the theoretical shape to determine the molecular mass accurately, probably due to the heterogeneity of the carbohydrate moiety. A decrease in mass by neuraminidase digestion, however, determined the average number of sialic acids in the molecule.