Progress Toward the Asymmetric Total Synthesis of Chaetoglobin A Selective Oxidative Homo- and Cross-Coupling of Phenols Using Aerobic Catalysts

The chaetoglobins are a structurally unique class of azaphilone alkaloid dimers with reported anticancer activity. They are also a potential platform for the development of antibacterial and botulinum antitoxin. Notably, this class of compounds has not been synthesized to date. Chaetoglobin A (1) and B (2) were originally isolated from the endophytic fungus Chaetomium globosum.1 Chaetoglobin A has been shown to be potentially active against human colon and breast cancer. However, the bioactivity of chaetoglobin B has not been studied due lack of material, suggesting the need of further research. The main goal of this project is the design and optimization of a synthetic route for chaetoglobin natural products. Achiral phenol coupling has been studied for many years; however, the regioselective methods reported to date are substrate-dependent and limited in scope. - Previously, we developed a regio- and enantioselective method for oxidative phenol coupling applying a series of bimetallic and monomeric vanadium catalysts. The aim of this project is to develop a new complementary method for regioselective oxidative phenol coupling. In collaboration with Trung Cao and Young Lee, 84 catalysts were synthesized and screened against a collection of phenolic substrates using High-Throughput Experimentation (HTE). We successfully identified catalysts that give high reactivity toward different substrates, and upon scale-up isolated the products in good yields

Trapping of light beams and formation of spatial solitary waves in quadratic nonlinear media

Summary form only given. In this paper we report the outcome of our comprehensive investigations to study the dynamics of the beam trapping in both bulk crystals and optical planar waveguides made of quadratic nonlinear media in second-harmonic generation configurations. We address and discuss the suitable experimental conditions required to form spatial solitary waves in critical phase-matching and quasi-phase-matching settings.Peer ReviewedPostprint (published version

Spatial Solitary Waves in Bulk Quadratic Non-Linear Materials and Their Applications

This invention encompasses generating electromagnetic solitary waves in two-transverse spatial dimensions. These wave beams propagate without diffraction and are equivalent to the normal modes of propagation of a nonlinear system governed by second order optical nonlinearities. The wave beams can be generated using optical techniques and will impact a wide variety of geometries and operating conditions whenever second order nonlinear optical processes are implemented for harmonic and parametric optical conversion. A preferred embodiment covers the generation of solitary waves from nonlinear materials such as KTiOPO.sub.4 (KTP) crystals. Other types of nonlinear optical device crystals can also be used such as KH.sub.2 PO.sub.4 (KDP), (NH.sub.2).sub.2 CO(Urea), LiNbO.sub.3, KNbO.sub.3, and the borate crystals BaB.sub.2 O.sub.4 (BBO) and LiB.sub.3 O.sub.7 (LBO)

Communicating Discovery-Based Research Results to the News: A Real-World Lesson in Science Communication for Undergraduate Students

Communicating science effectively to the general public is a necessary skill that takes practice. Generally, undergraduate science majors are taught to communicate to other scientists but are not given formal training on how to communicate with a nonscientist. An opportunity to appear on a news segment can be used as a real-world lesson on science communication for your students. This article will describe how to contact a producer to get your class on a news segment, ideas for types of research that may be of interest to the media, and how to practice communicating the results effectively

Cascading nonlinearities in an organic single crystal core fiber: The Cerenkov regime

The large nonlinear phase shifts imparted to the fundamental beam during Cerenkov second harmonic generation (SHG) in a DAN, 4-(N,N-dimethylamino)-3-acetamidonitrobenzene, single crystal core fiber are explained and modelled numerically. Cascading upconversion and downconversion processes leads to nonlinear phase shifts produced by the second order nonlinear coupling of the guided fundamental mode and the component of the Cerenkov second harmonic field trapped in the fiber cladding

Plane waves in periodic, quadratically nonlinear slab waveguides: stability and exact Fourier structure

We consider the propagation of broad optical beams through slab waveguides with a purely quadratic nonlinearity and containing linear and nonlinear long-period quasi-phase-matching gratings. An exact Floquet analysis on the periodic, plane-wave solution shows that the periodicity can drastically alter the growth rate of the modulational instability but that it never completely removes the instability. The results are confirmed by direct numerical simulation, as well as through a simpler, approximate theory for the averaged fields that accurately predicts the low-frequency part of the spectrum.Comment: 10 Pages, 13 figures (some in two parts) new version has some typos removed and extra references and explanation adde

On the generation and the nonlinear dynamics of X-waves of the Schroedinger equation

The generation of finite energy packets of X-waves is analysed in normally dispersive cubic media by using an X-wave expansion. The 3D nonlinear Schroedinger model is reduced to a 1D equation with anomalous dispersion. Pulse splitting and beam replenishment as observed in experiments with water and Kerr media are explained in terms of a higher order breathing soliton. The results presented also hold in periodic media and Bose-condensed gases.Comment: 18 pages, 6 figures, corrected version to be published in Physical Review

Necesidades presentes y futuras de recursos humanos en ocupaciones técnicas, diestras y clericales.

Resumen en español.Resumen en inglés