Advanced expander test bed program

The Advanced Expander Test Bed (AETB) is a key element in NASA's Space Chemical Engine Technology Program for development and demonstration of expander cycle oxygen/hydrogen engine and advanced component technologies applicable to space engines as well as launch vehicle upper stage engines. The AETB will be used to validate the high-pressure expander cycle concept, investigate system interactions, and conduct investigations of advanced mission focused components and new health monitoring techniques in an engine system environment. The split expander cycle AETB will operate at combustion chamber pressures up to 1200 psia with propellant flow rates equivalent to 20,000 lbf vacuum thrust. Contract work began 27 Apr. 1990. During 1992, a major milestone was achieved with the review of the final design of the oxidizer turbopump in Sep. 1992

Necessarily Hypocritical: The Legal Viability of EPA\u27s Regulation of Stationary Source Greenhouse Gas Emissions Under the Clean Air Act

The Supreme Court’s ruling in Massachusetts v. EPA made clear that greenhouse gases fall within the realm of air pollutants the Clean Air Act was designed to regulate. The Court’s decision sparked a chain reaction forcing the EPA to regulate greenhouse gases under different provisions of the Act. The EPA’s decision to regulate drew fierce criticism, especially from industries that would be forced to reduce emissions. Opponents argue that greenhouse gases are not traditional pollutants and therefore the drafters of the Clean Air Act did not intend them to be regulated. Furthermore, they argue that the EPA over-stepped its authority in “tailoring” a new rule to incorporate greenhouse gases more appropriately into the Act’s framework. This Note defends the EPA’s decision to regulate greenhouse gases, as well as its Tailoring Rule. In light of the Clean Air Act’s explicit language and legislative intent, the EPA was not only legally justified in implements its decision, but it had no other choice

Wilson Loops and Area-Preserving Diffeomorphisms in Twisted Noncommutative Gauge Theory

We use twist deformation techniques to analyse the behaviour under area-preserving diffeomorphisms of quantum averages of Wilson loops in Yang-Mills theory on the noncommutative plane. We find that while the classical gauge theory is manifestly twist covariant, the holonomy operators break the quantum implementation of the twisted symmetry in the usual formal definition of the twisted quantum field theory. These results are deduced by analysing general criteria which guarantee twist invariance of noncommutative quantum field theories. From this a number of general results are also obtained, such as the twisted symplectic invariance of noncommutative scalar quantum field theories with polynomial interactions and the existence of a large class of holonomy operators with both twisted gauge covariance and twisted symplectic invariance.Comment: 23 page

Cool early Albian climates; new data from Argentina

Previous studies on the stable isotope geochemistry of dimitobelid belemnites from Antarctica and Australia indicated cool climatic conditions during the early Albian in the shelf seas around the Gondwanan margin. In this paper new analyses from diagenetically unaltered specimens of Dimitobelus cf. stimulus from early Albian deposits of the Rio Mayer Formation of Lago San Martin, southern Argentina are presented. Oxygen isotope values for diagenetically least altered samples give values ranging between d18O C0.07 and C0.96 vPDB, which equate to a mean palaeotemperature of 9.5 (C (assuming dw of 1.2& SMOW). These data are consistent with a model of cool early Albian shelf seas in the Southern Hemisphere.Facultad de Ciencias Naturales y Muse

Cool early Albian climates; new data from Argentina

Previous studies on the stable isotope geochemistry of dimitobelid belemnites from Antarctica and Australia indicated cool climatic conditions during the early Albian in the shelf seas around the Gondwanan margin. In this paper new analyses from diagenetically unaltered specimens of Dimitobelus cf. stimulus from early Albian deposits of the Rio Mayer Formation of Lago San Martin, southern Argentina are presented. Oxygen isotope values for diagenetically least altered samples give values ranging between d18O C0.07 and C0.96 vPDB, which equate to a mean palaeotemperature of 9.5 (C (assuming dw of 1.2& SMOW). These data are consistent with a model of cool early Albian shelf seas in the Southern Hemisphere.Facultad de Ciencias Naturales y Muse

Disentangling the Structure-Activity Relationships of Naphthalene Diimides as Anticancer G-Quadruplex-Targeting Drugs

In the context of developing efficient anticancer therapies aimed at eradicating any sort of tumors, G-quadruplexes represent excellent targets. Small molecules able to interact with G-quadruplexes can interfere with cell pathways specific of tumors and common to all cancers. Naphthalene diimides (NDIs) are among the most promising, putative anticancer G-quadruplextargeting drugs, due to their ability to simultaneously target multiple G-quadruplexes and their strong, selective in vitro and in vivo anticancer activity. Here, all the available biophysical, biological, and structural data concerning NDIs targeting Gquadruplexes were systematically analyzed. Structure−activity correlations were obtained by analyzing biophysical data of their interactions with G-quadruplex targets and control duplex structures, in parallel to biological data concerning the antiproliferative activity of NDIs on cancer and normal cells. In addition, NDI binding modes to G-quadruplexes were discussed in consideration of the structures and properties of NDIs by in-depth analysis of the available structural models of G-quadruplex/NDI complexes

Cool early Albian climates; new data from Argentina

Previous studies on the stable isotope geochemistry of dimitobelid belemnites from Antarctica and Australia indicated cool climatic conditions during the early Albian in the shelf seas around the Gondwanan margin. In this paper new analyses from diagenetically unaltered specimens of Dimitobelus cf. stimulus from early Albian deposits of the Rio Mayer Formation of Lago San Martin, southern Argentina are presented. Oxygen isotope values for diagenetically least altered samples give values ranging between d18O C0.07 and C0.96 vPDB, which equate to a mean palaeotemperature of 9.5 (C (assuming dw of 1.2& SMOW). These data are consistent with a model of cool early Albian shelf seas in the Southern Hemisphere.Facultad de Ciencias Naturales y Muse

Tuning the polymorphism of the anti-VEGF G-rich V7t1 aptamer by covalent dimeric constructs

In the optimization process of nucleic acid aptamers, increased affinity and/or activity are generally searched by exploring structural analogues of the lead compound. In many cases, promising results have been obtained by dimerization of the starting aptamer. Here we studied a focused set of covalent dimers of the G-quadruplex (G4) forming anti-Vascular Endothelial Growth Factor (VEGF) V7t1 aptamer with the aim of identifying derivatives with improved properties. In the design of these covalent dimers, connecting linkers of different chemical nature, maintaining the same polarity along the strand or inverting it, have been introduced. These dimeric aptamers have been investigated using several biophysical techniques to disclose the conformational behavior, molecularity and thermal stability of the structures formed in different buffers. This in-depth biophysical characterization revealed the formation of stable G4 structures, however in some cases accompanied by alternative tridimensional arrangements. When tested for their VEGF165 binding and antiproliferative activity in comparison with V7t1, these covalent dimers showed slightly lower binding ability to the target protein but similar if not slightly higher antiproliferative activity on human breast adenocarcinoma MCF-7 cells. These results provide useful information for the design of improved dimeric aptamers based on further optimization of the linker joining the two consecutive V7t1 sequences