Preparation of Ca(1−x)EuxGa2S4 crystals and their photoluminescence, absorption and excitation spectra

The single crystal of CaGa₂S₄:Eu is expected as a useful laser material with a high quantum efficiency of light emission. However, as far as our knowledge is concerned, the systematic study of the mixed compounds of Ca_(1−x)Eu_xGa₂S₄ as a function of x has not been reported up to now. Here, we have first constructed the phase diagram of the CaGa₂S₄ and EuGa₂S₄ pseudo binary system, and show that it forms the solid solution. Then we have grown single crystals of these compounds. The maximum photoluminescence efficiency is achieved at x=0.25. From the three peak energies observed in the photoluminescence excitation (PLE) and absorption spectra, the 5d excited states are suggested to consist of three levels arising from the multiplets of Eu²⁺ ions.     

POSSIBLE ROLE OF METALLOTHIONEIN IN THE CELLULAR DEFENSE MECHANISM AGAINST UVB IRRADIATION IN NEONATAL HUMAN SKIN FIBROBLASTS

Abstract: The role of metallothionein (MT) in protecting skin cells against UVB irradiation was investigated. Fibroblast strains from normal adult (HS-K) and neonatal (NB1RGB) human skins as well as keratinocyte strains from human skin (SV40-HSK) and newborn Balb/c mouse skin (Pam 212) were exposed to UVB irradiation.
The sensitivity of HS-K and NB1RGB cells to UVB irradiation was similar; those of SV40-HSK and Pam 212 cells were two- and six-fold as sensitive to UVB irradiation as HS-K cells, respectively. The HS-K cells contained the greatest cellular reduced form of glutathione (GSH) levels compared to the three other skin cells: the levels were 13-, 7- and 6-fold of those in NB1RGB, SV40-HSK and Pam 212 cells, respectively. These results indicated that the sensitivity of skin cells to UVB irradiation was not always associated with their endogenous GSH levels. In particular, despite the fact that NB1RGB cells contained a relatively small amount of GSH, they were less sensitive to UVB irradiation.
NB1RGB cells contained 4–30 times more MT than those in other skin cells examined. The sulfhydryl residues of MT molecules in the NB1RGB cells were estimated to be mostly unoccupied by metals, suggesting they act in a similar way to those of GSH. Moreover, NB1RGB cells in which the MT content was elevated by dexamethasone (1 μ M ) or Zn²⁺ (7 μg/mL) treatment were more resistant to UVB irradiation than nontreated ones.
These results suggest that, at least in neonatal human skin fibroblasts, MT may play a role in protection against UVB irradiation.     

Raman spectra of anthracene negative ions in tetrahydrofuran solution

Raman spectra of anthracene mono- and di-negative ions in tetrahydrofuran solution were obtained by HeNe and Ar⁺ laser exciting lines. In addition to some frequency shifts from neutral anthracene, remarkable enhancement of intensities by the resonance Raman effect was observed for many aromatic ring vibrations.     

Structural modeling in a class of systems using fuzzy sets theory

On the basis of fuzzy sets theory, we propose a method for structuring hierarchy for the several complex problems, and call it Fuzzy Structural Modeling (FSM) method. An important requirement for structural modeling of complex systems is that the necessary data is acquired and organized into a form such that a structural model can be developed. The main purpose of this method is to describe and illustrate a formal procedure for constructing the graphic presentation of the hierarchical arrangement given the necessary information concerning the relation of each element to each other element. The procedure permits an automatic development of the graphic structure that portrays the hierarchy.     

Dual-labeled oligonucleotide probe for sensing adenosine via FRET: a novel alternative to SNPs genotyping

A novel FRET based strategy for DNA sequence analysis utilising base-discriminating fluorescence (BDF) nucleoside, (Py)U/(2-Ant)U, as donor in the dual-labelled oligonucleotide probe is reported; a selective/specific emission from acceptor, was observed upon excitation at the donor, only when the opposite base of the "smart" fluorescently labeled BDF nucleoside, (Py)U/(2-Ant)U, is adenine on the complementary target sequence.     

Reactions of polymerization-resistant 1,2-dithiolanes with lithiated oxygen heterocycles

Lithiated furans have been found to cleave the S–S bond of polymerization-resistant 1,2-dithiolanes to give the ring opened products in good yields. In the case of lithiated benzofuran, the excess reagent reacted with the normal product to give a mixture. Lithiated dihydrofuran and dihydropyran gave the corresponding ring-opened products that rearranged to spiro-1,3-dithianes during acidic workup. The reaction was applied to the selective synthesis of substrates for intramolecular Diels-Alder reactions. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:281–287, 1998     

Development of a new software for the X-ray structural analysis of polymer crystals by utilizing the X-ray imaging plate system

A software and some useful tools have been developed for identifying individual x-ray reflectional peaks recorded with an x-ray imaging plate system. These techniques were applied to analyze the crystal structure of uniaxially oriented polymer samples. Characteristic features of the present method may be summarized as follows. (1) The indexing of the observed reflections and the determination of the unit cell parameters can be made easily on the display of the computer. (2) The integrated intensity of the individual component of the overlapped reflections can be evaluated quantitatively through the curve separation technique. The R_merge's for the equivalent reflections were 5–6%, indicating the exact evaluation of the integrated intensities. (3) The thus obtained reflectional data were successfully utilized for the extraction of the initial structural models by the direct method. The actual applications have been made for orthorhombic polyethylene, trigonal polyoxymethylene, and isotactic polybutene-1, giving the refined crystal structures including even the positions of hydrogen atoms in some cases. The reliability factors were 12, 5, and 15%, respectively, for these three polymer cyrstals. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1677–1700, 1997     

Influence of Cu electroplating solutions on boron carbon nitride (BCN) film

Cu electroplating is required for the fabrication of Cu/low-k interconnections. The permeation of a plating solution into low-k films during Cu electroplating is a serious challenge for 45-nm nodes and more complex devices. We investigated the influence of Cu electroplating solutions on boron carbon nitride (BCN) as a low-k film. After dipping it into a Cu electroplating solution that contained additives, the BCN film's hydrophilic surface changed to a hydrophobic surface, and the incorporation of water into the BCN film was suppressed by surfactant adsorption. Sulfuric residue was detected on the BCN sample by thermal desorption spectroscopy after treatment in the Cu electroplating solution with additives; however, it was found through electrical measurements that this solution did not affect the leakage current or the dielectric constant of the BCN film. We successfully fabricated an electroplating Cu layer on a BCN film with good adhesion, and we believe that this BCN film is a sufficiently useful material for Cu/BCN integration in LSI.     

Growth and properties of YAlO film synthesized by RF magnetron sputtering

YAlO films are synthesized on (1 0 0)-oriented Si substrates by RF magnetron sputtering method. Al₂O₃ wafer is used as a target material, and some small pieces of Y bulk material are put on the Al₂O₃ target to synthesize YAlO films. Y composition ratio is varied from 0 to 34%. Amorphous YAlO films are characterized. An electrical resistivity as high as 3.4 × 10¹⁴ Ω-cm is achieved for the YAlO film with Y composition ratio of 10%. The dielectric constant increases with increasing Y composition ratio, and the YAlO film with Y composition ratio of 34% has a dielectric constant of 10.2. The bandgap energy of the YAlO film is suggested to be wider than 6.5 eV. YAlO films with a surface roughness of 0.4-1.3 nm are obtained irrespective of the Y composition ratio.     

Associative and segregative phase separations of gelatin/kappa-carrageenan aqueous mixtures

The effects of ionic strength, temperature, and pH on the phase separation behavior of type B pigskin gelatin/sodium-type kappa-carrageenan aqueous mixtures were investigated. Depending on the different combinations of temperature and sodium chloride (NaCl) concentration, the mixtures showed compatible, associative, and segregative phase separation behaviors. Additionally, a coexistence of associative and segregative (associative-co-segregative) phase separations was expected at low temperature and low NaCl concentration. These different phase separation events were observed using confocal scanning laser microscopy. Moreover, it was found that the segregative phase separation when alone is induced by the ordering of kappa-carrageenan chains, while that in the coexistence region is induced by the ordering of gelatin chains. pH had a significant effect on the associative phase separation, resulting in morphologies changing from compatible solution to liquid coacervate and further to solid precipitate with decreasing pH. These were attributed to the dramatic changes of the charge density of amphoteric gelatin during the pH decrease.