A Survey and Evaluation of High Energy Liquid Chemical Propulsion Systems

This report presents the results of a study to develop a procedure for evaluating liquid propellants in order (a) to select the most appropriate propellant (from among those under development) for each of several applications on each of the various missions in the NASA program, or (b) to select new propellants (from among those being proposed) for initiation or continuation of research and development. The analysis begins with a consideration of requirements--either for the specific application or for the various classes of applications. The known characteristics of the propellant or propellants to be evaluated are then put into a convenient form for evaluation. The next step is to determine whether or not there are requirements that simply cannot be met by the propellant. If the propellant passes this test, an optimum vehicle configuration using the propellant (and meeting all requirements) is estimated. (The configuration should be optimized with respect to the total resource consumption for all aspects of the mission, including R&D, production, logistics, and operation.) The total resource consumption for this configuration is then compared with that for similar configurations using other propellants (and meeting all requirements equally well). If all factors have been properly taken into account, this comparison of resource consumption will complete the evaluation. Such an evaluation may be performed several times, in increasing detail and with correspondingly increasing accuracy, as an R&D program proceeds, and the accuracy of the data as well as the cost of the next step in the program increase. The procedure is superior to those in common use in that it minimizes both the amount of analytical work and the number of points at which subjective value judgments are made

Preliminary evaluation of infrared and radar imagery, Washington and Oregon coasts

Airborne infrared and radar photography of Oregon and Washington coastal region

Hydrocarbon oxidation catalyzed by iron and manganese porphyrins anchored on aminofunctionalized supports

The second-generation metalloporphyrins (MePs) [5,10,15,20-tetrakis(pentafluorophenyl)porphyrin iron(III)] chloride, FeP, and [5,10,15,20-tetrakis(pentafluorophenyl)porphyrin manganese(III)] chloride, MnP, were covalently attached to aminofunctionalized supports, with a view to preparing selective solid catalysts for the oxidation of organic compounds. Montmorillonite K10 functionalized with 3-aminopropyltriethoxysilane (Mont1) or modified with 3-chloropropyltriethoxysilane followed by reaction with 1,6-diaminohexane (Mont2), and silica gel functionalized with 3-aminopropyltriethoxysilane (Sil1) or modified with 3-chloropropyltriethoxysilane followed by reaction with 1,6-diaminohexane (Sil2) were synthesized and characterized by UV-Vis and IR spectroscopies, EPR, TGA, and X-ray diffractometry. The catalytic activities of the MePs immobilized on these supports were investigated for the oxidation of (Z)-cyclooctene, cyclohexane and styrene by PhIO or H2O2. The studied systems were efficient catalysts for the oxidation of all substrates, especially when PhIO was the oxidant. There was no MeP leaching from the supports, indicating that covalent binding is a very efficient method for catalyst immobilization. The immobilized FePs were more efficient catalysts than the corresponding MnPs, even when imidazole was employed as a cocatalyst for the supported MnPs. Although the yields of oxidized products obtained with H2O2 were lower than those achieved with PhIO, some heterogeneous MeP systems were more efficient than the parent MePs in solution, both in terms of product yield and selectivity.As metaloporfirinas de segunda geração (MePs), cloreto de [5,10,15,20-tetraquis(pentafluorofenil)porfirinaferro(III)], FeP, e cloreto de [5,10,15,20-tetraquis(pentafluorofenil)porfirinamanganês(III)], MnP, foram covalentemente ancoradas em suportes aminofuncionalizados, com o objetivo de preparar catalisadores sólidos seletivos para a oxidação de compostos orgânicos. Montmorillonita K10 funcionalizada com 3-aminopropiltrietoxissilano (Mont1) ou com 3-cloropropiltrietoxissilano seguida por reação com 1,6-diaminoexano (Mont2), e sílica gel funcionalizada com 3-aminopropiltrietoxissilano (Sil1) ou modificada com 3-cloropropiltrietoxissilano seguida por reação com 1,6-diaminoexano (Sil2) foram preparadas e caracterizadas por UV-Vis, IR, EPR, TGA e difratometria de raios X. As atividades catalíticas das MePs imobilizadas nestes suportes foram investigadas na oxidação de (Z)-cicloocteno, cicloexano e estireno por iodosilbenzeno (PhIO) ou H2O2. Os sistemas estudados foram catalisadores eficientes da oxidação de todos os substratos, especialmente utilizando PhIO como oxidante. Não se observou lixiviamento das MePs dos suportes, indicando que a ligação covalente é um método muito eficiente para a imobilização de catalisadores. As FePs imobilizadas foram catalisadores mais eficientes que as correspondentes MnPs, mesmo quando imidazol foi empregado como um co-catalisador para as MnPs ancoradas. Embora os rendimentos de produtos oxidados utilizando H2O2 tenham sido mais baixos que aqueles obtidos com PhIO, alguns sistemas heterogêneos envolvendo MePs foram mais eficientes que as correspondentes MePs em solução, tanto em termos de rendimento de produto quanto de seletividade.FAPESPCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)CNP

Synthesis, characterization of a new carbonylated zirconium metallocene using a dichloro-zirconocene derived from partially alkylated s-indacene

Indexación: ScieloThis work describes the synthesis and characterization of new organometallic species, an unprecedented mononuclear zirconium complex bearing a tetraalkylated s-indacene ligand, and secondly, its respective dicarbonyl complex obtained by reduction with Mg/HgCl2. Theoretical calculations of these two compounds were carried out to gain further understanding of these novel molecular systems.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072009000300014&lng=es&nrm=is

Targeting of arenavirus RNA synthesis by a carboxamide-derivatized aromatic disulfide with virucidal activity.

Several arenaviruses can cause severe hemorrhagic fever (HF) in humans, representing a public health threat in endemic areas of Africa and South America. The present study characterizes the potent virucidal activity of the carboxamide-derivatized aromatic disulfide NSC4492, an antiretroviral zinc finger-reactive compound, against Junín virus (JUNV), the causative agent of Argentine HF. The compound was able to inactivate JUNV in a time and temperature-dependent manner, producing more than 99 % reduction in virus titer upon incubation with virions at 37 °C for 90 min. The ability of NSC4492-treated JUNV to go through different steps of the multiplication cycle was then evaluated. Inactivated virions were able to bind and enter into the host cell with similar efficiency as control infectious particles. In contrast, treatment with NSC4492 impaired the capacity of JUNV to drive viral RNA synthesis, as measured by quantitative RT-PCR, and blocked viral protein expression, as determined by indirect immunofluorescence. These results suggest that the disulfide NSC4492 targets on the arenavirus replication complex leading to impairment in viral RNA synthesis. Additionally, analysis of VLP produced in NSC4492-treated cells expressing JUNV matrix Z protein revealed that the compound may interact with Z resulting in an altered aggregation behavior of this protein, but without affecting its intrinsic self-budding properties. The potential perspectives of NSC4492 as an inactivating vaccinal compound for pathogenic arenaviruses are discussed.Fil: Sepúlveda, Claudia Soledad. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Quimica Biologica;Fil: Garcia, Cybele. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Quimica Biologica;Fil: Levingston Mac Leod, Jesica Mariana. Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Cs. y Tecnologia "dr. Cesar Milstein";Fil: Lopez, Nora Mabel. Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Pque. Centenario. Instituto de Cs. y Tecnologia "dr. Cesar Milstein";Fil: Damonte, Elsa Beatriz. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Quimica Biologica