京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20200号 / 理博第4285号 / 新制||理||1615(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 大須賀 篤弘, 教授 依光 英樹, 教授 丸岡 啓二 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Two indole-based squaraine dyes bonded to two pyrenyl groups through vinyl- and ethynyl- linkers were synthesized with the aim of enhancing the intramolecular charge transfer interaction in addition to improving their optical properties. The absorption and emission properties of these derivatives were determined in order to gain an insight into the intensity of this type of interaction, their aggregation behavior and compare them with results obtained through quantum chemical calculations. Both compounds presented high photochemical stability in THF, and the linear spectroscopic characterization revealed high extinction coefficients, large fluorescence quantum yields and relatively low tendency of forming excimers in several solvents. The nonlinear spectroscopic study revealed two-photon absorption cross section maxima greater than 10,000 GM (1 GM = 1 × 10-50 cm4 s/photon), which are improved values in comparison with the indole-based squaraine core. The experimental results were compared with time-dependent DFT calculations. These observations propose a new trend in the formulation of highly absorbing organic molecules containing pyrenyl groups for the development of new materials with Organic Light-Emitting Diode (OLED) applications. Moreover, this work contributes to the study of intramolecular charge transfer interaction and its tailoring for the improvement of the linear and nonlinear optical properties.

No description available.

Thesis advisor: Jia Niu / Thesis advisor: Abhishek Chatterjee / The functions of natural nucleic acids such as DNA and RNA have transcended from serving as the primary information carrier in cells and have emerged as a new class of functional material with applications encompassing medicine, diagnosis, and research tools. While the vulnerability of natural nucleic acids to nuclease degradation as well as the lack of chemical functionality have imposed a significant constraint on their ever-expanding applications, scientists have put in the effort to develop new classes of synthetic nucleic acids (XNAs) to overcome current limitations. In this dissertation, we will describe the development of a novel XNA oligonucleotide structure, the “click handle-modified FANA” (cmFANA), as the next-generation nucleic acid-based biopolymer that is capable of post-polymerization functionalization and evolution. In this dissertation, we divide our graduate research into three chapters: the development of the essential building block for cmFANA and the synthesis of cmFANA oligonucleotide as Chapter 1; the evolution and application of cmFANA as a sugar-presenting affinity reagent that targets disease-related Carbohydrate-Binding Proteins (CBPs) as Chapter 2; and other collaboration projects as Chapter 3. Together, we described a highly potential XNA structure that goes beyond established impressions of nucleic acids and carries the ability to be a versatile platform technology. / Thesis (PhD) — Boston College, 2023. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

<p>The Gram-positive, soil dwelling bacteria of the genus <em>Streptomyces</em> produce greater than 50% of the clinically relevant antibiotics in use today. Thanks to the falling price of DNA sequencing, <em>Streptomyces</em> genomes are revealing that they encode more secondary metabolites (potential antibiotics) than they produce under standard laboratory conditions. By heterologously overexpressing the known pleiotropic regulators of antibiotic expression from <em>Streptomyces coelicolor</em> in several other <em>Streptomyces</em> species it has been shown that the secondary metabolite profile of these species can be influenced. While present-day methods of introducing genes (conjugation) and screening for antibiotics work well on a small scale, the low throughput nature of these protocols stand as a barrier to testing this hypothesis on a larger scale. The focus of the research presented here was to develop high throughput (HTP) methods of engineering and screening <em>Streptomyces</em>. With these two technologies in place, an attempt was to made to introduce three plasmids (pSET152-<em>ermE*</em>p-null, pSET152-<em>ermE</em>*p-<em>atrA</em> and pSET152-<em>ermE</em>*p-<em>lsr2_NTD</em>) into 120 wild-isolate <em>Streptomyces</em> species from the Wright Actinomycete Collection. Exconjugants were successfully obtained for all three plasmids in 48 species of <em>Streptomyces</em> and were screened for increased antimicrobial activity using a HTP, <em>lux</em>-based bioassay. Numerous strains showed increased antimicrobial activity but WAC00206, WAC00230 and WAC00263 with pSET152-<em>ermE</em>*p-<em>lsr2_NTD</em>showed the most promising improvement in antimicrobial activity. These hits have been designated as high priority for future investigation. These results suggest that HTP conjugation and the <em>lux</em>-based bioassay are powerful methods for introducing plasmids into and screening engineered streptomycetes.</p> / Master of Science (MSc)

The work described in this dissertation can be divided into two parts. The first part is an investigation of the transient behavior and stability property of a phase conjugate resonator (PCR) below threshold. The second part is an experimental and theoretical study of the PCR's spatiotemporal dynamics above threshold. The time-dependent coupled wave equations for four-wave mixing (FWM) in a photorefractive crystal, with two distinct interaction regions caused by feedback from an ordinary mirror, was used to model the transient dynamics of a PCR below threshold. Analytical expressions of the steady state cavity's fields for the case of nondepleted pumps and an absorption free medium were derived and used to determine the self-oscillation conditions. The solutions, through simple frequency domain transformation techniques, were used to define the PCR's transfer function and analyse its stability. Taking into account pump depletion and medium absorption, the transient buildup and decay times of the cavity's fields as well as the specularly reflected and phase conjugate reflected intensities were numerically calculated as functions of a number of system parameters such as the coupling parameter and the pump and probe ratios. General trends were unveiled and discussed in view of the possible use of the PCR in image storage or processing architectures. Experimental results for the buildup and decay times confirmed qualitatively the predicted behavior. / Ph. D.

An optical image feedback system utilizing a cavity with a phase-conjugate mirror (PCM) has been studied. A new theory, based on operators, is developed to describe the steady-state output of the cavity. The use of operators allows one to describe the various optical operations and transformations needed in the optical implementation of iterative algorithms. The characteristics of the cavity are discussed using an expansion of the cavity fields in the cavity eigenfunctions. Several image processing applications using a PCM cavity are proposed and are studied using computer simulations. These theoretical studies indicate that a PC11 cavity can be useful in many applications. Optical phase conjugation was realized using a single crystal of photorefractive BaTi0₃ in a degenerated four-wave mixing geometry. The reflectivity gain from the PCM was optimized experimentally by the geometrical parameters and by the beamintensity ratios. The ability of the PCM to remove phase distortion as predicted theoretically, was demonstrated experimentally. The output of a PCM cavity can be substantially influenced by self-oscillations of the cavity above threshold. This was experimentally studied by observing the time evolution of the input. To avoid the influence of self-oscillation, the cavity must be operated below threshold. It is found that the cavity decay time constant diverges at and about threshold. This can be used as an indicator to show whether the cavity has crossed the threshold or to measure how close to threshold the cavity operates. To verify that a PCM cavity can be used in iterative image processing, an experiment was set up to implement an image restoration scheme based on the Gerchberg algorithm. It is shown that an optical implementation of the Gerchberg algorithm is feasible for objects made of few pixels. The experiment confirmed .that image iteration in a PCm cavity is possible. The limitations of the cavity and the technical difficulties are discussed. / Ph. D.

The spatiotemporal dynamics of a photorefractive phase-conjugate resonator (PPCR) is studied both experimentally and analytically. The resonator is a confocal cavity bounded by a dielectric mirror and a phase-conjugate mirror in a four wave mixing geometry. The effect of the Bragg mismatch, which is caused by the misalignment of the pump fields, is experimentally shown to break the cylindrical symmetry of the system and to increase the speed of the dynamics. By studying the first non stationary state at a cavity Fresnel number of F=2.0, the effect of the transverse component of the mismatch is shown to add a transverse phase to the wavefront of the phase-conjugate field, leading to the periodic nucleation of a pair of phase defects. A model of this state is developed in terms of the competition of a few transverse patterns. The model is experimentally verified using a holographic optical correlator designed to identify the modes presumed by the model. The dynamics are also studied using a Karhunen-Loeve decomposition in which the eigenvectors of the covariance matrix are calculated. The covariance matrix is obtained from the transverse intensity fluctuations of the cavity field and the eigenvectors are interpreted as the active cavity modes of the resonator. The results of the application of this experimental method to the F=2.0 state match those obtained by the correlator. This demonstrates its validity as a useful tool for studying the system. Application of the decomposition to states at higher F reveal that aperiodic and periodic states can have very similar active mode structures. An analytical model of the PPCR is then developed using a plane wave decomposition of the cavity field and the n1aterial variables contained in Kukhtarev's equations. Numerical simulations using the model demonstrate its accuracy. In addition, the different effects of the longitudinal and transverse components of the Bragg mismatch on the dynamics and defect nucleation are revealed. The relevant assumptions involved in the development of the model are discussed in detail. / Ph. D.

Yes / Biosynthetic materials have emerged as one of the most exciting and productive fields in polymer chemistry due to their widespread adoption and potential applications in tissue engineering (TE) research. In this work, we report the synthesis of a poly(ε-caprolactone)-graft-collagen (PCL-g-Coll) copolymer. We combine its good mechanical and biodegradable PCL properties with the great biological properties of type I collagen as a functional material for TE. PCL, previously dissolved in dimethylformamide/dichloromethane mixture, and reacted with collagen using carbodiimide coupling chemistry. The synthesised material was characterised physically, chemically and biologically, using pure PCL and PCL/Coll blend samples as control. Infrared spectroscopy evidenced the presence of amide I and II peaks for the conjugated material. Similarly, XPS evidenced the presence of C–N and N–C=O bonds (8.96 ± 2.02% and 8.52 ± 0.63%; respectively) for PCL-g-Coll. Static contact angles showed a slight decrease in the conjugated sample. However, good biocompatibility and metabolic activity was obtained on PCL-g-Coll films compared to PCL and blend controls. After 3 days of culture, fibroblasts exhibited a spindle-like morphology, spreading homogeneously along the PCL-g-Coll film surface. We have engineered a functional biosynthetic polymer that can be processed by electrospinning. / The EPSRC Centre in Innovative Manufacturing in Medical Devices (MeDe Innovation; EP/K029592/1).

京都大学 / 新制・課程博士 / 博士(工学) / 甲第25270号 / 工博第5229号 / 新制||工||1997(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 西村 文武, 教授 松田 知成, 准教授 浅田 安廣, 准教授 井原 賢(高知大学) / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM