Syringolin A, a plant elicitor, was isolated in 1998 and has been identified as a potential anti-cancer compound based on its activity against proteasome. The unique structure of this natural product consists of a 12-membered diamide ring, formed by two non-proteinogenic amino acids 3,4-dehydrolysine and 5-methyl-4-amino-2-hexenoic acid, and a bis(valinyl)urea side chain which is connected to the macrocycle by a peptide bond. The construction of this challenging macrocylic core was achieved by a macrolactamization reaction using peptide coupling reagents BOP/HOAt, while the two (E)-configured double bonds in the ring were introduced by a Johnson-Claisen rearrangement and Wittig olefination respectively. Ru(bpy)3Cl2 which is an excellent visible light photoredox catalyst, has been extensively applied to organic syntheses in recent years. Although much research has focused on the study of the reductive quenching pathway, the oxidative quenching pathway has rarely been explored. Using persulfate as the electron acceptor, we have successfully developed a protocol for the oxidative functionalization of dialkylamides under mild reaction conditions. Further application has demonstrated a Friedel-Crafts amidoalkylation methodology applying various nucleophilic alcohols and arenes. The reaction can also be conducted under thermolysis condition without the photocatalyst, but requires elevated temperature. Both of the reactions generate N-acyliminium ion in situ as the key intermediate. The first example of photocatalytic halogenation has been achieved at room temperature using Ru(bpy)3Cl2 and polyhalomethanes (CBr4 and CHI3) as the electron acceptors. Excellent yields and high functional group tolerance have been established. Mechanistic studies indicate a single electron transfer (SET) pathway and the transformation is via a Vilsmeier-Haack type intermediate. Further expansion of this methodology to anhydride formation was achieved, providing a mild avenue for the synthesis of symmetric anhydrides. Furthermore, the use of a continuous flow reactor enabled the efficient large scale synthesis of anhydrides.

Recently witnessed a great popularity of unobtrusive Visible Light Communication (VLC) using screen-camera channels. They overcomes the inherent drawbacks of traditional approaches based on coded images like bar codes. One popular unobtrusive method is the utilizing of alpha channel or color channels to encode bits into the pixel translucency or color intensity changes with over-the-shelf smart devices. Specifically, Uber-in-light proves to be an successful model encoding data into the color intensity changes that only requires over-the-shelf devices. However, Uber-in-light only exploit Multi Frequency Shift Keying (MFSK), which limits the overall throughput of the system since each data segment is only 3-digit long. Motivated by some previous works like Inframe++ or Uber-in-light, in this thesis, we proposes a new VLC model encoding data into color intensity changes on red and blue channels of video frames. Multi-Phase-Shift-Keying (MPSK) along with MFSK are used to match 4-digit and 5-digit long data segments to specific transmission frequencies and phases. To ensure the transmission accuracy, a modified correlation-based demodulation method and two learning-based methods using SVM and Random Forest are also developed.

1,4-dioxane is an emerging contaminant and fully miscible organic compound which has been found extensively in wastewater effluent. Conventional water treatment technologies like carbon adsorption, and air stripping are inefficient in removing this extremely mobile and persistent contaminant from water. In this study, different types of metallic nanoparticles, e.g., nanoscale zero-valent iron (nZVI), γFe2O3, and Fe(III)-doped TiO2 were used to investigate the removal of 1,4-dioxane under visible light. These nanoparticles were characterized with scanning electron microscope (SEM), transmission electron microscope (TEM) and dynamic light scattering (DLS). The experiments were first carried out using deionized water (DIW) at pH 7 and pH 3. nZVI was found more efficient than other nanoparticles under visible light irradiation at pH 3. No 1,4-dioxane removal was obtained for all cases at pH 7 under visible light, or at pH 3 in dark. Moreover, light intensity also plays a significant role in 1,4-dioxane removal. Removal of 22.3%, 40.0% and >99.9% of 1.4-dioxane was reached under 2.4 mW/cm2, 2.6 mw/cm2 and 3.25 mW/cm2 light intensities, respectively, after 6 h of irradiation. The most efficient nanoparticle nZVI was applied to wastewater effluent from Carbondale Southeast Wastewater Treatment Plant. From the results, it was found that 1,4-dioxane degradation took longer time in wastewater effluent than in DIW, because of the presence of other constituents in the wastewater sample. nZVI is also capable of removing 1,4-dioxane in presence of trichloroethylene (TCE) and tetrachloroethylene (PCE) at pH 3 under visible light. In comparison, TiO2 nanoparticle is capable of degrading 1,4-dioxane under visible light or under sunlight at pH 7. Moreover, TiO2 removed 1,4-dioxane in presence of both TCE and PCE at pH 7 under visible light or sunlight. This study found a cost-effective and efficient solution for removing 1,4-dioxane from wastewater effluent that can be reused, by using metallic nanoparticles under visible light.

Gallium nitride (GaN) is a semiconductor material highly regarded for visible light generation since it provides the most efficient platform for compact violet, blue, and green light emitters, and in turn, high-quality and ubiquitous white lighting. Despite this fact, the potential of the GaN platform has not been fully exploited. This potential must enable the precise control in the various properties of light, realizing functions beyond the conventional. Simultaneously, the field of the telecommunications is looking for candidate technologies fit for wireless transmission in the next generations of communication. Visible light communication (VLC) may play a significant role in the future of the last mile of the network by providing both a fast internet connection and a high-quality illumination. Hence, a variety of optoelectronic platforms, including distributed-feedback (DFB) lasers, superluminescent diodes (SLDs), and multi-section lasers, can be used to exploit the full potential of GaN while offering unprecedented solutions for VLC and other applications, such as atomic clocks, high-resolution fluorescence microscopy, and on-chip nonlinear processing at visible wavelengths. This dissertation demonstrates green and sky-blue DFB lasers based on GaN, with resolution-limited single-mode emission at wavelengths around 514 nm and 480 nm, side-mode suppression ratio as large as 42.4 dB, and application to up to 10.5 Gbit/s data transmission. Preliminary observations of DFB lasers with emission close to the Fraunhofer lines are presented, offering a pathway for low-background noise applications. Blue-emitting SLDs are used to demonstrate a 3.8 Gbit/s transmitter while achieving spectral efficiency of up 118.2 (mW・nm)/(kA/cm2) in continuous-wave operation. Visual quality is confirmed by coherence length and white light generation. Short-wavelength SLDs have the potential for higher resolution and fluorescence excitation in classical optical coherence tomography and fiber gyroscopes. The demonstration of a two-section green laser diode is presented, achieving coupled-cavity lasing at wavelengths of 514 nm based on an integrated green laser–absorber in self-colliding pulse configuration, operated in continuous-wave electrical injection. The integrated laser offer potential for mode- locked and Q-switched lasing. The integrated laser is suitable for reconfiguration where laser–modulator, laser–absorber, and laser–amplifier are proposed and investigated at green wavelengths.

Photocatalysis is an advanced oxidation process for the purification and remediation of contaminated waters and wastewaters, and is advantageous over conventional treatment technologies due to its ability to degrade emerging and recalcitrant pollutants. In addition, photocatalytic disinfection is less chemical-intensive than other methods such as chlorination, and can inactivate even highly resistant microorganisms with good efficacy. Process sustainability and cost-effectiveness may be improved by utilizing solar irradiation as the source of necessary photons for photocatalyst excitation. However, solar-induced activity of the traditionally-used titania is poor due to its inefficient visible light absorption, and recombination of photo-excited species is problematic. Additionally, mass transfer limitations and difficulties separating the catalyst from the post-treatment slurry hinder conversions and efficiencies obtainable in practice. In this research, various strategies were explored to address these issues using novel visible light active photocatalysts. Two classes of carbon-enhanced photocatalytic materials were studied: activated carbon adsorbent photocatalyst composites, and carbon-doped TiO2. Adsorbent photocatalyst composites based on activated carbon and plasmonic silver/silver chloride structures were synthesized, characterized, and experimentally investigated for their photocatalytic activity towards the degradation of model organic pollutants (methyl orange dye, phenol) and the inactivation of a model microorganism (Escherichia coli K-12) under visible light. The adsorptive behaviour of the composites towards methyl orange dye was also studied and described according to appropriate models. Photocatalytic bacterial inactivation induced by the prepared composites was investigated, and the inactivation mechanisms and roles of incorporated antimicrobial silver on disinfection were probed and discussed. These composites were extended towards magnetic removal strategies for post-use separation through the incorporation of magnetic nanoparticles to prepare Ag/AgCl-magnetic activated carbon composites, and the effect of nanoparticles addition on the properties and photoactivities of the resulting materials was explored. Another silver/silver halide adsorbent photocatalyst composite based on activated carbon and Ag/AgBr exhibiting visible light absorption due to both localized surface plasmon resonance and optical band gap absorption was synthesized and its photocatalytic activity towards organics degradation and microbial inactivation was studied. Carbon-doped mixed-phase titania was also prepared and experimentally investigated.

京都大学 / 新制・課程博士 / 博士(エネルギー科学) / 甲第23536号 / エネ博第427号 / 新制||エネ||81(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 石原 慶一, 教授 佐川 尚, 准教授 奥村 英之 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20337号 / 工博第4274号 / 新制||工||1662(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 庸裕, 教授 梶 弘典, 教授 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21118号 / 工博第4482号 / 新制||工||1696(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 阿部 竜, 教授 安部 武志, 教授 作花 哲夫 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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