The polarized transmittance and reflectance spectra of β-Ga2O3 crystals are investigated, and the data are interpreted in terms of the monoclinic crystal band structure. The energies of the absorption edge can be divided into six ranges, and these ranges can be assigned to the transitions from the valence bands to the conduction band minimum according to the selection rules. The indirect bandgap-energy of 4.43 eV is smaller than the direct bandgap-energy of 4.48 eV at RT; and the energy difference of 0.05 eV nearly matches the theoretically calculated values of 0.03–0.04 eV.

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We have developed a femtosecond time-resolved luminescence spectroscopy by the optical Kerr-gate ͑OKG͒ method to investigate ultrafast carrier dynamics and relaxation processes of materials. Solid glasses with a high nonlinear refractive index were used as the Kerr media to obtain a subpicosecond time resolution. When a quartz plate was used as the Kerr medium, the Kerr efficiency and the instrumental response time of our spectroscopic system were 5-10 % and ϳ250 fs, respectively. By employing the OKG method, we revealed the internal conversion from S 2 to S 1 state of ␤-carotene with a low fluorescence quantum yield and an ultrafast fluorescence decay time, and the lifetime of the S 2 state was determined to be 210 fs. An advantage of the OKG method relative to the conventional up-conversion technique is its ability to directly obtain time-resolved luminescence spectra, and thus the OKG method might be superior to the up-conversion technique to investigate ultrafast carrier dynamics and relaxation processes of materials.

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The temporal evolution of the photoexcited state in quasi-one-dimensional ͑1D͒ halogen-bridged platinum complexes ͓Pt(en) 2 ͔͓Pt(en) 2 X 2 ͔(ClO 4 ) 4 ͑abbreviated as Pt-X, XϭCl, Br or I͒, has been comprehensively studied by femtosecond time-resolved luminescence spectroscopy. In Pt-Cl, new short-lived hot luminescence is found in the low-energy side of a self-trapped exciton ͑STE͒ luminescence band. The overall behavior of the STE luminescence band within 2 ps is well explained by the vibrational relaxation of the STE. The behavior is reproduced by a model calculation based on wave packet propagation on an interaction mode composed of frequency-dispersed bulk phonons. This model is also applied to the previous results in Pt-Br. For both Pt-Cl and Pt-Br, the frequency spectra of phonons which compose the interaction mode have been estimated. In Pt-I, the STE luminescence decays much faster than those in Pt-Cl and Pt-Br, showing existence of more effective nonradiative decay channel.

A new asymmetric, squarylium cyanine dye functionalized by boronic acid ("SQ-BA") was designed and synthesized for on-capillary labeling of gram-positive bacteria to provide for high sensitivity detection by way of a modified form of capillary electrophoresis with laser induced fluorescence detection (CE-LIF). The CE-based separation employed a polymer-enhanced buffer with capillary transient isotachophoresis in a new hybrid method dubbed "PectI." It was found that the addition of various monosaccharides to SQ-BA in a batch aqueous solution greatly enhanced the emission of the boronic acid functionalized dye by a factor of up to 18.3 at a long wavelength (λ(ex) = 630 nm, λ(em) = 660 nm) with a high affinity constant (K = ~10(2.80) M(-1)) superior to other sugar probes. Semiempirical quantum mechanics calculations suggest that the mechanism for this high enhancement may involve the dissociation of initially nonemissive dye associates (stabilized by an intramolecular hydrogen bond) upon complex formation with sugars. The fluorescence emission of SQ-BA was also significantly enhanced in the presence of a gram-positive bacterial spore, Bacillus globigii (Bg), which serves as a simulant of B. anthracis (or anthrax) and which possesses a peptidoglycan (sugar)-rich spore coat to provide ample sites for interaction with the dye. Several peaks were observed for a pure Bg sample even with polyethyleneoxide (PEO) present in the CE separation buffer, despite the polymer's previously demonstrated ability to focus microoorganisms to a single peak during migration. Likewise, several peaks were observed for a Bg sample when capillary transient isotachophoresis (ctITP) alone was employed. However, the new combination of these techniques as "PectI" dramatically and reproducibly focused the bacteria to a single peak with no staining procedure. Using PectI, the trace detection of Bg spores (corresponding to approximately three cells per injection) along with separation efficiency enough to separate Bg from another gram-positive bacteria, Saccharomyces cerevisiae (resolution, R(s) = 6.09, and apparent plate number, N = 2.7-3.3 × 10(5)), were successfully achieved.

We present a rapidly neutralizable and highly anticoagulant thrombin-binding aptamer with a short toehold sequence, originally discovered by systematic evolution of ligands by exponential enrichment (SELEX) with microbead-assisted capillary electrophoresis (MACE). MACE is a novel CE-partitioning method for SELEX and able to separate aptamers from a library of unbound nucleic acids, where the aptamer and target complexes can be detected reliably and partitioned with high purity even in the first selection cycle. Three selection rounds of MACE-SELEX discovered several TBAs with a nanomolar affinity (K d = 4.5–8.2 nM) that surpasses previously reported TBAs such as HD1, HD22, and NU172 (K d = 118, 13, and 12 nM, respectively). One of the obtained aptamers, M08, showed a 10- to 20-fold longer prolonged clotting time than other anticoagulant TBAs, such as HD1, NU172, RE31, and RA36. Analyses of the aptamer and thrombin complexes using both bare and coated capillaries suggested that a large number of efficient aptamers are missed in conventional CE-SELEX because of increased interaction between the complex and the capillary. In addition, the toehold-mediated rapid antidote was designed for safe administration. The efficient aptamer and antidote system developed in the present study could serve as a new candidate for anticoagulant therapy.