Redondo Resort and Recreation Area Development

The area proposed for development in this project consists of the Baca Location #1, in the Jemez Mountains, located in North Central New Mexico, approximately seventy-five miles north of Albuquerque, and twenty miles west of Los Alamos. The area consists of 97,000 acres, owned by a private individual

Optimizing the fine lock performance of the Hubble Space Telescope fine guidance sensors

This paper summarizes the on-orbit performance to date of the three Hubble Space Telescope Fine Guidance Sensors (FGS's) in Fine Lock mode, with respect to acquisition success rate, ability to maintain lock, and star brightness range. The process of optimizing Fine Lock performance, including the reasoning underlying the adjustment of uplink parameters, and the effects of optimization are described. The Fine Lock optimization process has combined theoretical and experimental approaches. Computer models of the FGS have improved understanding of the effects of uplink parameters and fine error averaging on the ability of the FGS to acquire stars and maintain lock. Empirical data have determined the variation of the interferometric error characteristics (so-called 's-curves') between FGS's and over each FGS field of view, identified binary stars, and quantified the systematic error in Coarse Track (the mode preceding Fine Lock). On the basis of these empirical data, the values of the uplink parameters can be selected more precisely. Since launch, optimization efforts have improved FGS Fine Lock performance, particularly acquisition, which now enjoys a nearly 100 percent success rate. More recent work has been directed towards improving FGS tolerance of two conditions that exceed its original design requirements. First, large amplitude spacecraft jitter is induced by solar panel vibrations following day/night transitions. This jitter is generally much greater than the FGS's were designed to track, and while the tracking ability of the FGS's has been shown to exceed design requirements, losses of Fine Lock after day/night transitions are frequent. Computer simulations have demonstrated a potential improvement in Fine Lock tracking of vehicle jitter near terminator crossings. Second, telescope spherical aberration degrades the interferometric error signal in Fine Lock, but use of the FGS two-thirds aperture stop restores the transfer function with a corresponding loss of throughput. This loss requires the minimum brightness of acquired stars to be about one magnitude brighter than originally planned

Heat transfer with very high free-stream turbulence and streamwise vortices

Results are presented for two experimental programs related to augmentation of heat transfer by complex flow characteristics. In one program, high free stream turbulence (up to 63 percent) was shown to increase the Stanton number by more than a factor of 5, compared with the normally expected value based on x-Reynolds number. These experiments are being conducted in a free-jet facility, near the margins of the jet. To a limited extent, the mean velocity, turbulence intensity, and integral length scale can be separately varied. The results show that scale is a very important factor in determining the augmentation. Detailed studies of the turbulence structure are being carried out using an orthogonal triple hot-wire anemometer equipped with a fourth wire for measuring temperature. The v' component of turbulence appears to be distributed differently from u' or w'. In the second program, the velocity distributions and boundary layer thicknesses associated with a pair of counter-rotating, streamwise vortices were measured. There is a region of considerably thinned boundary layer between the two vortices when they are of approximately the same strength. If one vortex is much stronger than the other, the weaker vortex may be lifted off the surface and absorbed into the stronger

Competitive formation of spiro and ansa derivatives in the reactions of tetrafluorobutane-1,4-diol with hexachlorocyclotriphosphazene: a comparison with butane-1,4-diol

Reaction of hexachlorocyclotriphosphazene, N3P3Cl6 (1), in two stoichiometries (1:1.2 and 1:3) with the sodium derivative of the fluorinated diol, 2,2,3,3-tetrafluorobutane-1,4-diol, (2), in THF solution at room temperature afforded six products, whose structures have been characterized by X-ray crystallography and 1H, 19F and 31P NMR spectroscopy: the mono-spiro compound, N3P3Cl4(OCH2CF2CF2CH2O), (3), its ansa isomer, (4), a di-spiro derivative N3P3Cl2(OCH2CF2CF2CH2O)2, (5), its spiro-ansa (6) and non-gem cis bis-ansa (7) isomers and a tri-spiro compound N3P3(OCH2CF2CF2CH2O)3, (8). The tri-spiro derivative (8) was also formed in the reaction of the ansa compound (4) with diol (2) in a 1:3 ratio in THF at room temperature. The reactions of (1) with step-wise additions of (2) were also investigated at low temperature (-780C) to give the same range of products as at room temperature. The results of all reactions are compared with previous work on the reactions of (1) with butane-1,4-diol/pyridine mixtures and with the reaction of hexafluorocyclotriphosphazene, N3P3F6 (9), with the silyl derivative of the diol (2), (Me3SiOCH2CF2)2, in a 1:0.4 mole ratio in the same solvent, THF

Stereoisomerism in pentaerythritol-bridged cyclotriphosphazene tri-spiranes: spiro and ansa 1,3-propanediyldioxy disubstituted derivatives

Four isomeric products were isolated and purified from the reaction of 1,3-propanediol with the tetra-spirane cyclophosphazene-organophosphate compound (1): viz. the di-monospiro (2a), di-monoansa (2b) and two monospiro-monoansa derivatives (2c) and (2d). It is shown by 31P NMR spectroscopy on addition of a chiral solvating agent (CSA) that both the di-monospiro (2a) and di-monoansa (2b) derivatives are racemates, as expected, whereas no splitting of NMR signals occurred on addition of CSA to solutions of (2c) and (2d). It is found by X-ray crystallography that the two monospiro-monoansa spirane derivatives, (2c) and (2d), are meso diastereoisomers, which represent a new case of the stereochemistry of bis di-substituted cyclophosphazene derivatives of (1). It is also observed from the 31P NMR spectrum of the reaction mixture, supported by the yields of pure compounds, that formation of a spiro group is about 4.5 times more likely than that of an ansa moiety under the conditions of the reaction

Structural and stereogenic properties of spiro- and ansa-substituted 1,3-propanedioxy derivatives of a spermine-bridged cyclotriphosphazene

Reaction of 1,3-propanediol with the achiral spermine-bridged cyclophosphazene 1 at various molar ratios in THF gives a number of spiro-and ansa-derivatives that exhibit different stereogenic properties, viz. racemic, meso or achiral forms. As expected, spiro forms are preferred (giving mono-, di-, tri- and tetra-substitution), although significant amounts of mono- and di-substituted ansa derivatives also occur. A number of new structures have been characterized by NMR spectroscopy and X-ray crystallography in this work; mono-spiro 2, di-mono-ansa 6 and di-spiro/mono-ansa 8. The mono-ansa compound 3 was observed in solution by NMR spectroscopy but no evidence was found for the monospiro/monoansa 5, a necessary precursor of compound 8. The tri-spiro derivative 7 has been isolated and characterized by 31P NMR spectroscopy, whereas the structures of the di-monospiro 4 (meso) and tetra-spiro 9 have been characterized previously. The stereogenic properties of many of the products have been confirmed by X-ray crystallography and/or by 31P NMR spectroscopy on addition of the chiral solvating agent, (S)-(+)-2,2,2-trifluoro-1-(9-anthryl)ethanol. Although the starting compound 1 is achiral, it is found that unsymmetrically-substituted derivatives with 1,3-propanediol give racemic mixtures for the mono-spiro 2 and tri-spiro 7 derivatives, whereas symmetrically-substituted derivatives such as di-mono-ansa 6 and di-spiro/mono-ansa 8 are meso. It is found that care must taken in interpreting the 'splitting' of 31P NMR signals on addition of CSA in terms of 'chirality' of molecules, because some meso compounds give false positive results due to changes from A2X-like to A2B or ABX spin systems

The importance of the hydrophilic region of PsbL for the plastoquinone electron acceptor complex of Photosystem II

AbstractThe PsbL protein is a 4.5kDa subunit at the monomer–monomer interface of Photosystem II (PS II) consisting of a single membrane-spanning domain and a hydrophilic stretch of ~15 residues facing the cytosolic (or stromal) side of the photosystem. Deletion of conserved residues in the N-terminal region has been used to investigate the importance of this hydrophilic extension. Using Synechocystis sp. PCC 6803, three deletion strains: ∆(N6–N8), ∆(P11–V12) and ∆(E13–N15), have been created. The ∆(N6–N8) and ∆(P11–V12) strains remained photoautotrophic but were more susceptible to photodamage than the wild type; however, the ∆(E13–N15) cells had the most severe phenotype. The Δ(E13–N15) mutant showed decreased photoautotrophic growth, a reduced number of PS II centers, impaired oxygen evolution in the presence of PS II-specific electron acceptors, and was highly susceptible to photodamage. The decay kinetics of chlorophyll a variable fluorescence after a single turnover saturating flash and the sensitivity to low concentrations of PS II-directed herbicides in the Δ(E13–N15) strain indicate that the binding of plastoquinone to the QB-binding site had been altered such that the affinity of QB is reduced. In addition, the PS II-specific electron acceptor 2,5-dimethyl-p-benzoquinone was found to inhibit electron transfer through the quinone-acceptor complex of the ∆(E13–N15) strain. The PsbL Y20A mutant was also investigated and it exhibited increased susceptibility to photodamage and increased herbicide sensitivity. Our data suggest that the N-terminal hydrophilic region of PsbL influences forward electron transfer from QA through indirect interactions with the D–E loop of the D1 reaction center protein. Our results further indicate that disruption of interactions between the N-terminal region of PsbL and other PS II subunits or lipids destabilizes PS II dimer formation. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: Keys to Produce Clean Energy

The extrinsic proteins of Photosystem II

In this review we examine the structure and function of the extrinsic proteins of Photosystem II. These proteins include PsbO, present in all oxygenic organisms, the PsbP and PsbQ proteins, which are found in higher plants and eukaryotic algae, and the PsbU, PsbV, CyanoQ, and CyanoP proteins, which are found in the cyanobacteria. These proteins serve to optimize oxygen evolution at physiological calcium and chloride concentrations. They also shield the Mn 4CaO 5 cluster from exogenous reductants. Numerous biochemical, genetic and structural studies have been used to probe the structure and function of these proteins within the photosystem. We will discuss the most recent proposed functional roles for these components, their structures (as deduced from biochemical and X-ray crystallographic studies) and the locations of their proposed binding domains within the Photosystem II complex. This article is part of a Special Issue entitled: Photosystem II. © 2011 Elsevier B.V. All rights reserved