Spectroscopic Applications of Integrated Tunable Solid-State Dye Laser

A novel type of tunable laser is developed that integrates dye-doped plastics laser waveguides with a distributed feedback structure. The waveguide matrix is dye doped poly-hydroxyethylmethacrylate:methylmethacrylate, and a single-mode waveguide is achieved by refractive index control. The wavelength coverage is over 560-1100 nm using a frequency doubled Nd:YAG microchip laser. The miniaturizing of the optical-pumped solid-state dye laser extended the lifetime to more than million shots and decreased the required laser threshold energy to less than 1 $mUJ. Novel type spectroscopic applications using the multiple wavelength laser array chip are also proposed and demonstrated.     

Crosslinking of oligomers bearing carbamoyloxyimino groups with their photochemical and thermal reactions

Carbamoyloxyimino (COI) groups are precursors of photochemically base‐generating groups as well as those of thermally isocyanate‐generating groups. In this study, photochemical and thermal reactions of COI groups in oligomers were investigated by spectral analyses and solubility changes. Oligomers bearing three types of COI groups were prepared. COI groups in all oligomer films were photolyzed on irradiation with 254 nm of light and were deblocked to form isocyanato groups on heating. From the IR spectral analyses, the formation of urea linkage was confirmed by the decrease in isocyanato groups and peak generation because of urea groups on postexposure bake (PEB) treatment. For all oligomer films, PEB was effective for the enhancement of insolubilization of the films in tetrahydrofuran. Heating followed by irradiation was also effective for the insolubilization. These results indicated that photochemical and thermal treatments of COI groups afforded highly sensitive crosslinking systems because of photochemically generated basic groups and thermally generated isocyanato groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2612–2620, 2004     

Crystallization and structure formation of block copolymers containing a glassy amorphous component

Formation of higher‐order structure in crystallization from microphase‐separated melts was studied for polystyrene–polyethylene (PS–PE) diblock copolymers and PS–PE–PS triblock copolymers with time‐resolved synchrotron small‐angle X‐ray scattering (SR–SAXS) techniques. The PE block was crystallized at temperatures when the PS block was in the glassy state. In both crystallization and melting processes, only the peak intensity in the SR–SAXS curve changed, however, the peak positions including higher‐order peaks did not change. This means that the microphase‐structure in the crystalline state was completely the same as that in the molten state. These behaviors were observed regardless of any melt microphase structure. Also, once a stable microphase structure was formed in the molten state, the structure was not changed even if crystallization and melting were repeated. Behavior of crystallization from such microphase‐separated melts was also studied. Apparent activation energies of crystallization were high for all block copolymers, compared with that for the PE homopolymer. In particular, the triblock copolymers showed higher apparent activation energies than the diblock copolymers. Both degrees of crystallinity and Avrami indices were greatly suppressed in crystallization from the cylindrical domain. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4199–4206, 2004     

Photocrosslinking system using multifunctional epoxy crosslinkers having thermally degradable properties

A novel thermally degradable photocrosslinking system was investigated. Difunctional and trifunctional epoxides with tertiary ester linkages were synthesized. When blended films of epoxides and poly(vinyl phenol) or epoxides and poly(methacrylic acid‐co‐ethyl methacrylate) with a photoacid generator were irradiated and then baked at relatively low temperatures (<100 °C), the films became insoluble in solvents. The heating conditions strongly affected the insoluble fractions of the blends. The insoluble fractions of the blended films containing the trifunctional epoxide were higher than the fractions of the films containing the difunctional epoxide. The crosslinked films became soluble after baking at relatively high temperatures (>120 °C). The reaction pathway of the blended system was studied with in situ Fourier transform infrared measurements. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3685–3696, 2004     

Coordination and solvation of copper ion: infrared photodissociation spectroscopy of Cu(+)(NH(3))(n) (n = 3-8)

Coordination and solvation structures of the Cu(+)(NH(3))(n) ions with n = 3-8 are studied by infrared photodissociation spectroscopy in the NH-stretch region with the aid of density functional theory calculations. Hydrogen bonding between NH(3) molecules is absent for n = 3, indicating that all NH(3) molecules are bonded directly to Cu(+) in a tri-coordinated form. The first sign of hydrogen bonding is detected at n = 4 through frequency reduction and intensity enhancement of the infrared transitions, implying that at least one NH(3) molecule is placed in the second solvation shell. The spectra of n = 4 and 5 suggest the coexistence of multiple isomers, which have different coordination numbers (2, 3, and 4) or different types of hydrogen-bonding configurations. With increasing n, however, the di-coordinated isomer is of growing importance until becoming predominant at n = 8. These results signify a strong tendency of Cu(+) to adopt the twofold linear coordination, as in the case of Cu(+)(H(2)O)(n).     

The recrystallization technique for local plastic-zone observation in type 304 stainless steel in the temperature range of −196° to 950° C

The recrystallization technique has been extended for direct observation of plastic zone in Type 304 stainless steel in the temperature range of ?196° to 950°C. It can reveal plastic deformation with plastic strain above 0.02 in the range of ?196° to 850° C and that with plastic strain above 0.06 at 950°C. Results of plastic-zone observation in notched specimen in the range of ?196° to 950° C are presented to illustrate the technique's capability.     

Structural characterization and subcellular localization of <Emphasis Type="Italic">Drosophila</Emphasis> organic solute carrier partner 1

Background

Organic solute carrier partner 1 (OSCP1) is known to facilitate the transport of various organic solutes into cells and reported to play a role in cell growth and cell differentiation. Moreover, OSCP1 is known as a tumor suppressor gene that is frequently down-expressed in nasopharyngeal carcinomas and acute myeloid leukemia. However, the underlying mechanisms of action remain unclear and the subcellular localization of OSCP1 has yet to be determined in detail.

Results

Drosophila contains a single orthologue of OSCP1 (dOSCP1) that shares 58% homology with its human counterpart. To study the expression pattern and subcellular localization of dOSCP1, we prepared a specific antibody. Subcellular localization analyses of dOSCP1 with these revealed localization in the plasma membrane, endoplasmic reticulum, Golgi apparatus and mitochondria, but no detection in cytosol. dOSCP1 signals were also detected in the nucleus, although at weaker intensity than in plasma membranes and subcellular organelles. In addition, native polyacrylamide gel electrophoresis analysis with and without β-mercaptoethanol treatment revealed that recombinant dOSCP1 forms dimers and trimers in solution. The dimer form of dOSCP1 could also be detected by Western immunoblot analyses in third instar larval extracts.

Conclusions

The data revealed that dOSCP1 localizes not only in the plasma membrane but also in the nucleus, ER, Golgi apparatus and mitochondria. It is therefore conceivable that this protein may interact with various partners or form multimeric complexes with other proteins to play multiple roles in cells, providing clues to understanding the functions of dOSCP1 during Drosophila development.

     

Our research on proton pumping ATPases over three decades: their biochemistry,molecular biology and cell biology

ATP is synthesized by F-type proton-translocating ATPases (F-ATPases) coupled with an electrochemical proton gradient established by an electron transfer chain. This mechanism is ubiquitously found in mitochondria, chloroplasts and bacteria. Vacuolar-type ATPases (V-ATPases) are found in endomembrane organelles, including lysosomes, endosomes, synaptic vesicles, etc., of animal and plant cells. These two physiologically different proton pumps exhibit similarities in subunit assembly, catalysis and the coupling mechanism from chemistry to proton transport through subunit rotation. We mostly discuss our own studies on the two proton pumps over the last three decades, including ones on purification, kinetic analysis, rotational catalysis and the diverse roles of acidic luminal organelles. The diversity of organellar proton pumps and their stochastic fluctuation are the important concepts derived recently from our studies.     

Fast shrinking kinetics of poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) hydrogels containing a nonionic surfactant

Shrinking kinetics of poly(N-isopropylacrylamide) gels prepared in the presence of a nonionic surfactant C9PE10 was investigated. The shrinking rate of the gels containing more than 6 wt.% of C9PE10 showed about a thousand-fold increase. From the analysis of the shrinking process and the small-angle X-ray scattering profiles, the fast shrinking kinetics was attributed to the incorporation of spatial heterogeneity of the network structure, which is caused by the addition of the surfactant.