ANTITUMOR AND GASTROPROTECTIVE SCREENING OF SOME NOVEL ORGANIC DERIVATIVES OF BISMUTH

Objectives: The objectives of present manuscript are to synthesize some new organic derivatives of bismuth having general formula (RBiL2; wherein R = C6F5; L = Substituted aromatic carboxylic acid), and characterized with the help of M.P., elemental, I.R., and NMR spectral analysis to ascertain the structure of novel compounds. These compounds were also characterized for their in vitro antitumor activity against human breast (MCF-7) and mammary cancer (EVSA-7) cell line along with gastroprotective (anti-ulcer) activity in rats using standard methods. Methods: All the newly organobismuth having general formula (RBiL2) were synthesised by earliar reported methods especially using redistribution and complexation reactions. The in-vitro antitumor and gastroprotective studies were performed by using standard protocols and methods. Results: It was found that the compounds were crystalline solids, air stable, and soluble in common organic solvent, have sharp melting points, and possess trigonal/pyramidal structure, exhibit higher activity than the standard ranitidine when the tests were carried out with aspirin induced and moderate activity was seen when the tests were done with ethanol induced along with potential antitumor activity against MCF-7 and EVSA-7 cell lines. Conclusion: The newly synthesized organobismuth complexes were characterized to ascertain their structure by sophisticated instrumental and spectral analysis resulted as trigonal/pyramidal structure. The compounds were also screened 1st time for gastroprotective and antitumor activity in vitro. The observations clearly indicate that organobismuth carboxylates as reported here show potential gastroprotective and antitumor activity in vitro

Anisotropic Third-Harmonic Generation of Exfoliated As2S3 Thin Flakes

Van der Waals (vdW) materials have recently attracted significant interest in the context of orientation-dependent linear and nonlinear optical properties. Recently, arsenic trisulfide (As2S3) or orpiment is identified as a new vdW layered material having anisotropic vibrational and optomechanical responses due to the reduced in-plane crystal symmetry, but its nonlinear optical response is still not well understood yet. Herein, the anisotropic third-harmonic generation (THG) response of mechanically exfoliated As2S3 thin flakes is reported. The polarization-dependent evolution of THG emission from butterfly-shaped pattern to four-lobe pattern is comprehensively explored. Moreover, the third-order nonlinear susceptibility of As2S3 crystal is extracted by analyzing the thickness-dependent THG emission. We anticipate that the discussed results will not only update the existing understanding on the nonlinear light-matter interaction in anisotropic vdW materials, but also promote future applications in integrated photonic circuits, on-chip nonlinear signal processing, and polarization-sensitive optical devices

太陽光発電システムと系統連系に関する研究 -モデリング、制御器設計、最適化-

九州工業大学博士学位論文（要旨）学位記番号：生工博甲第278号 学位授与年月日：平成29年3月24

Naturally Occurring Layered Mineral Franckeite with Anisotropic Raman Scattering and Third-Harmonic Generation Responses

Vertically stacked van der Waals (vdW) heterostructures have introduced a unique way to engineer optical and electronic responses in multifunctional photonic and quantum devices. However, the technical challenges associated with the artificially fabricated vertical heterostructures have emerged as a bottleneck to restrict their proficient utilization, which emphasizes the necessity of exploring naturally occurring vdW heterostructures. As one type of naturally occurring vdW heterostructures, franckeite has recently attracted significant interest in optoelectronic applications, but the understanding of light-matter interactions in such layered mineral is still very limited especially in the nonlinear optical regime. Herein, the anisotropic Raman scattering and third-harmonic generation (THG) from mechanically exfoliated franckeite thin flakes are investigated. The observed highly anisotropic Raman modes and THG emission patterns originate from the low-symmetry crystal structure of franckeite induced by the lattice incommensurability between two constituent stacked layers. The thickness-dependent anisotropic THG response is further analyzed to retrieve the third-order nonlinear susceptibility for franckeite crystal. The results discussed herein not only provide new insights in engineering the nonlinear light-matter interactions in natural vdW heterostructures, but also develop a testbed for designing future miniaturized quantum photonics devices and circuits based on such heterostructures

Polarization-Sensitive Optical Responses from Natural Layered Hydrated Sodium Sulfosalt Gerstleyite

Multi-element layered materials have gained substantial attention in the context of achieving the customized light-matter interactions at subwavelength scale via stoichiometric engineering, which is crucial for the realization of miniaturized polarization-sensitive optoelectronic and nanophotonic devices. Herein, naturally occurring hydrated sodium sulfosalt gerstleyite is introduced as one new multi-element van der Waals (vdW) layered material. The mechanically exfoliated thin gerstleyite flakes are demonstrated to exhibit polarization-sensitive anisotropic linear and nonlinear optical responses including angle-resolved Raman scattering, anomalous wavelength-dependent linear dichroism transition, birefringence effect, and polarization-dependent third-harmonic generation (THG). Furthermore, the third-order nonlinear susceptibility of gerstleyite crystal is estimated by the probed flake thickness-dependent THG response. We envisage that our findings in the context of polarization-sensitive light-matter interactions in the exfoliated hydrated sulfosalt layers will be a valuable addition to the vdW layered material family and will have many implications in compact waveplates, on-chip photodetectors, optical sensors and switches, integrated photonic circuits, and nonlinear signal processing applications

Mechanism and kinetics of Aztreonam hydrolysis catalyzed by class-C β-lactamase : a temperature-accelerated sliced sampling study

Enhanced sampling of large number of collective variables (CVs) is inevitable in molecular dynamics (MD) simulations of complex chemical processes such as enzymatic reactions. Because of the computational overhead of hybrid quantum mechanical/molecular mechanical (QM/MM)-based MD simulations, especially together with density functional theory, predictions of reaction mechanism, and estimation of free-energy barriers have to be carried out within few tens of picoseconds. We show here that the recently developed temperature-accelerated sliced sampling method allows one to sample large number of CVs, thereby enabling us to obtain rapid convergence in free-energy estimates in QM/MM MD simulation of enzymatic reactions. Moreover, the method is shown to be efficient in exploring flat and broad free-energy basins that commonly occur in enzymatic reactions. We demonstrate this by studying deacylation and reverse acylation reactions of aztreonam drug catalyzed by a class-C β lactamase (CBL) bacterial enzyme. Mechanistic details and nature of kinetics of aztreonam hydrolysis by CBL are elaborated here. The results of this study point to characteristics of the aztreonam drug that are responsible for its slow hydrolysis