2,285 research outputs found

    2-C-Cyclo­hexyl-2,3-O-isopropyl­idene­erythrofuran­ose

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    In the title compound, C13H22O4, the acetonide ring adopts an envelope conformation with one of the O atoms as the flap atom, whereas a twisted conformation is found for the furan­ose ring. Centrosymmetric eight-membered {⋯OCOH}2 synthons involving the hydr­oxy H and acetonide O atoms are found in the crystal structure. These are linked into a supra­molecular chain in the a-axis direction via C—H⋯O contacts

    2,3-O-Isopropyl­idene-3-C-phenyl­erythrofuran­ose

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    The title compound, C13H16O, comprises two fused five-membered rings. Each ring has an envelope conformation, with the ether O atom in the furan­ose ring, and the CMe2 atom in the acetonide ring as the flap atoms. In the crystal, centrosymmetrically related mol­ecules associate via hydr­oxy–ether O—H⋯O hydrogen bonds and the resulting dimers are linked into a supra­molecular chain with a flattened topology via C—H⋯Ohydr­oxy contacts, and aligned in the a-axis direction

    Di-tert-butyl (2R,3R)-2-{[(2E)-3-(4-acet­yloxy-3-meth­oxy­phen­yl)prop-2-eno­yl]­oxy}-3-hy­droxy­butane­dioate

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    In the title mol­ecule, C24H32O10, one tert-butyl ester group is folded towards the central benzene ring while the other is directed away. The acetyl group is almost perpendicular to the benzene ring to which it is connected [C—C—O—C torsion angle = 90.4 (12)°]. The conformation about the ethene bond [1.313 (7) Å] is E. The atoms of the benzene ring and its attached ester group and part of the hy­droxy tert-butyl ester side chain are disordered over two sets of sites in a 50:50 ratio. Linear supra­molecular chains along the a axis mediated by hy­droxy–carbonyl O—H⋯O hydrogen bonds feature in the crystal packing. The same H atom also partakes in an intra­molecular O—H⋯O inter­action

    2-(2-Methyl­naphtho[2,1-b]furan-1-yl)acetic acid

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    In the title mol­ecule, C15H12O3, the two six-membered and one five-membered fused-ring system is almost planar and the CH2C(=O)OH residue is essentially orthogonal to it. In the crystal structure, centrosymmetric dimers are formed via the carboxylic acid {⋯O=C—O—H}2 synthon

    Methyl 2-(5-bromo-2-methyl­naphtho[2,1-b]furan-1-yl)acetate

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    The three fused six-, six- and five-membered rings in the title compound, C16H13BrO3, are coplanar, the CH2C(=O)OCH3 residue being twisted out of this plane [dihedral angle = −26.9 (4)°]. Centrosymmetric dimers are found in the crystal structure stabilized by C—H⋯O inter­actions involving the furan O atom

    RSRM Segment Train Derailment and Recovery

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    On May 2, 2007, a freight train carrying segments of the space shuttle's solid rocket boosters derailed in Myrtlewood, Alabama, after a rail trestle collapsed. The train was carrying Reusable Solid Rocket Motors (RSRM) 98 center and forward segments (STS-120) and RSRM 99 aft segments (STS-122). Initially, it was not known if the segments had been seriously damaged. Four segments dropped approximately 10 feet when the trestle collapsed and one of those four rolled off the track onto its side. The exit cones and the other four segments, not yet on the trestle, remained on solid ground. ATK and NASA immediately dispatched an investigation and recovery team to determine the safety of the situation and eventually the usability of the segments and exit cones for flight. Instrumentation on each segment provided invaluable data to determine the acceleration loads imparted into each loaded segment and exit cone. This paper details the incident, recovery plan and the team work that created a success story that ended with the safe launch of STS120 using the four center segments and the launch of STS122 using the Aft exit cones assemblies

    On the Evolution Equation for Magnetic Geodesics

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    In this paper we prove the existence of long time solutions for the parabolic equation for closed magnetic geodesics.Comment: In this paper we prove the existence of long time solutions for the parabolic equation for closed magnetic geodesic

    1,4-Di-tert-butyl (2R,3R)-2-({(2E)-3-[4-(acet­yloxy)phen­yl]prop-2-eno­yl}­oxy)-3-hy­droxy­butane­dioate

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    The title compound, C23H30O9, has an approximate T-shape with the tert-butyl ester groups lying either side of the benzene ring. The acetyl group is almost perpendicular to the benzene ring to which it is connected [C—C—O—C torsion angle = −106.7 (3)°]. The conformation about the C=C double bond [1.331 (4) Å] is E. Linear supra­molecular chains along the a axis mediated by hy­droxy–carbonyl O—H⋯O hydrogen bonds feature in the crystal packing. The same H atom is also involved in an intra­molecular O—H⋯O inter­action

    Shallow Rupture Propagation of Pleistocene Earthquakes Along the Hurricane Fault, UT, Revealed by Hematite (U-Th)/He Thermochronometry and Textures

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    The material properties and distribution of faults above the seismogenic zone promote or inhibit earthquake rupture propagation. We document the depths and mechanics of fault slip along the seismically active Hurricane fault, UT, with scanning and transmission electron microscopy and hematite (U-Th)/He thermochronometry. Hematite occurs as mm-scale, striated patches on a \u3e10 m2 thin, mirror-like silica fault surface. Hematite textures include bulbous aggregates and cataclasite, overlain by crystalline Fe-oxide nanorods and an amorphous silica layer at the slip interface. Textures reflect mechanical, fluid, and heat-assisted amorphization of hematite and silica-rich host rock that weaken the fault and promote rupture propagation. Hematite (U-Th)/He dates document episodes of mineralization and fault slip between 0.65 and 0.36 Ma at ∼300 m depth. Data illustrate that some earthquake ruptures repeatedly propagate along localized slip surfaces in the shallow crust and provide structural and material property constraints for in models of fault slip
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