VARIOUS SYNTHETIC PATHWAYS TOWARDS EFAVIRENZ AND ITS ANALOGS; THE REPLACEMENT OF THE SIDE CHAIN

Cyclopropyl acetylene (CA) is a key intermediate in the synthesis of the human immunodeficiency virus (HIV) reverse transcriptase inhibitor, Efavirenz (EFV), an antiviral drug used to treat HIV. CA is an expensive raw material, difficult to obtain, and employed in the preparation of medications to combat acquired immunodeficiency syndrome (AIDS). It was found that the structure could be synthesized by the utilization of PCl5; however, this resulted in unwanted ring opening products. To address this issue, a one pot synthesis was developed using Ph3PCl2 as a mild chlorinating agent. In addition, a new analog has been proposed substituting the cyclopropyl group for alternative cyclic hydrocarbons. Instead of using a cyclopropyl ring, a larger ring with more than three carbons can result in less ring strain and subsequently, less ring opening. Previous experiments have tested other ring structures; however, larger cyclic hydrocarbons have yet to be studied within these conditions. Efforts toward the synthesis of higher order analogs including cyclobutyl acetylene will be discussed once the optimal yield using a variety of bases for the synthesis is determined. Various reaction procedures are detaile

Cold-Flow Testing of a Subscale Model Exhaust System for a Space-Base Laser

The purpose of this research was to continue a study of gas-dynamic phenomena that occurred in stacked cylindrical rings of nozzles and an exhaust manifold as reported by Captain Scott Bergren in 2002. The rings and exhaust manifold were part of a 1/5-scale model of one quadrant of the conceptual Space Based Laser Integrated Flight Experiment (SBL IFX) gas dynamic laser. This model was mated to a blow- down/vacuum wind tunnel and consisted of a nozzle array, centerbody, supersonic diffuser, and a transition structure to mate the vacuum and test section. During Capt Bergren\u27s research, supersonic flow was found to only last for 0.2 seconds from wind tunnel startup. The short duration of the supersonic flow was due to the transition structure being too small and not being able to swallow the shock wave. The objectives of this research were to remodel the transition structure and evaluate the test section to see if simulation of the expected fluid flow properties in the conceptual SBL IFX design was possible using cold-flow. The transition structure was remodeled to capture the entire vacuum line entrance area while still mating to the diffuser exit. Using rapid data acquisition and schlieren photography, results indicated that supersonic flow lasted for approximately 10 seconds from startup. During this time, a well-defined oblique shock wave inside the optical cavity attached to the leading edge of the centerbody, where the flow reached a velocity of Mach 2.8

Characterizing omega-limit sets which are closed orbits

AbstractLet X be a vector field in a compact n-manifold M, n⩾2. Given Σ⊂M we say that q∈M satisfies (P)Σ if the closure of the positive orbit of X through q does not intersect Σ, but, however, there is an open interval I with q as a boundary point such that every positive orbit through I intersects Σ. Among those q having saddle-type hyperbolic omega-limit set ω(q) the ones with ω(q) being a closed orbit satisfy (P)Σ for some closed subset Σ. The converse is true for n=2 but not for n⩾4. Here we prove the converse for n=3. Moreover, we prove for n=3 that if ω(q) is a singular-hyperbolic set [C. Morales, M. Pacifico, E. Pujals, On C1 robust singular transitive sets for three-dimensional flows, C. R. Acad. Sci. Paris Sér. I 26 (1998) 81–86], [C. Morales, M. Pacifico, E. Pujals, Robust transitive singular sets for 3-flows are partially hyperbolic attractors or repellers, Ann. of Math. (2) 160 (2) (2004) 375–432], then ω(q) is a closed orbit if and only if q satisfies (P)Σ for some Σ closed. This result improves [S. Bautista, Sobre conjuntos hiperbólicos-singulares (On singular-hyperbolic sets), thesis Uiversidade Federal do Rio de Janeiro, 2005 (in Portuguese)] and [C. Morales, M. Pacifico, Mixing attractors for 3-flows, Nonlinearity 14 (2001) 359–378]

Expanding Hope in Payatas

Informal settlements, also known as slums or squatter settlements, are a way of life for millions around the world, especially within urban centers. The challenge is to provide a better quality of life, both physically and socially. This thesis provides a critical look into the conditions, limitations, strengths, and hopes of the community of Payatas in Metro Manila, Philippines, with recommendations of measures to support and strengthen the community, by building upon the community’s positive elements to develop social impact

Atomic Processes in Planetary Nebulae and H II Regions

Spectroscopic studies of Planetary Nebulae (PNe) and H {\sc ii} regions have driven much development in atomic physics. In the last few years the combination of a generation of powerful observatories, the development of ever more sophisticated spectral modeling codes, and large efforts on mass production of high quality atomic data have led to important progress in our understanding of the atomic spectra of such astronomical objects. In this paper I review such progress, including evaluations of atomic data by comparisons with nebular spectra, detection of spectral lines from most iron-peak elements and n-capture elements, observations of hyperfine emission lines and analysis of isotopic abundances, fluorescent processes, and new techniques for diagnosing physical conditions based on recombination spectra. The review is directed toward atomic physicists and spectroscopists trying to establish the current status of the atomic data and models and to know the main standing issues.Comment: 9 pages, 1 figur