785 research outputs found
Tests of gravitational symmetries with radio pulsars
No full textSymmetries play important roles in modern theories of physical laws. In this paper, we review several experimental tests of important symmetries associated with the gravitational interaction, including the universality of free fall for self-gravitating bodies, time-shift symmetry in the gravitational constant, local position invariance and local Lorentz invariance of gravity, and spacetime translational symmetries. Recent experimental explorations for post-Newtonian gravity are discussed, of which, those from pulsar astronomy are highlighted. All of these tests, of very different aspects of gravity theories, at very different length scales, favor to very high precision the predictions of the strong equivalence principle (SEP) and, in particular, general relativity which embodies SEP completely. As the founding principles of gravity, these symmetries are motivated to be promoted to even stricter tests in future.SCI(E)[email protected]; [email protected]
End-capping of conjugated thiophene-benzene aromatic systems
No full textThe synthesis of end-capped thieno[3,2-f:4,5-f′]bis[1]benzothiophene was achieved from thiophene and 2,5-thiophenedicarboxaldehyde. Specifically, hexyl and dodecyl end-capping groups conferred reversible redox behavior as evidenced by cyclic voltammetry with oxidation potentials of 0.73 V versus Fc-Fc+ couple. An extensive spectrophotometric analysis is reported. © 2010 Elsevier Ltd. All rights reserved.Barrash-Shiftan N, 1998, J PHYS ORG CHEM, V11, P743, DOI 10.1002-(SICI)1099-1395(1998100)11:10743::AID-POC393.0.CO;2-H; BAUERLE P, 1993, SYNTHESIS-STUTTGART, P1099, DOI 10.1055-s-1993-26009; Brusso JL, 2008, CHEM MATER, V20, P2484, DOI 10.1021-cm7030653; Coropceanu V, 2006, CHEM-EUR J, V12, P2073, DOI 10.1002-chem.200500879; Degheili JA, 2009, J PHYS CHEM A, V113, P1244, DOI 10.1021-jp8098363; Fichou D., 1999, HDB OLIGO POLYTHIOPH; Gao P, 2010, CHEM-EUR J, V16, P5119, DOI 10.1002-chem.200903562; Hains AW, 2010, ACS APPL MATER INTER, V2, P175, DOI 10.1021-am900634a; Helgesen M, 2010, MACROMOLECULES, V43, P1253, DOI 10.1021-ma9024812; Horowitz G, 2004, J MATER RES, V19, P1946, DOI 10.1557-JMR.2004.0266; Kagan C. R., 2003, THIN FILM TRANSISTOR; KALYANASUNDARAM K, 1977, J AM CHEM SOC, V99, P2039, DOI 10.1021-ja00449a004; Lakowicz J. R., 1999, PRINCIPLES FLUORESCE; LIPPERT E, 1957, Z ELEKTROCHEM, V61, P962; MATAGA N, 1956, B CHEM SOC JPN, V29, P465, DOI 10.1246-bcsj.29.465; Miyazaki E, 2009, J MATER CHEM, V19, P5913, DOI 10.1039-b910824f; MIYAZAKI E, 2008, Patent No. 2008108442; Moustafa RM, 2009, J PHYS CHEM A, V113, P1235, DOI 10.1021-jp809830x; Parker C.A., 1968, PHOTOLUMINESCENCE SO; Reichardt C., 1988, SOLVENTS SOLVENT EFF; REICHARDT C, 1994, CHEM REV, V94, P2319, DOI 10.1021-cr00032a005; SARAF SD, 1974, J MATH SCI, V1, P75; Shinamura S, 2010, J ORG CHEM, V75, P1228, DOI 10.1021-jo902545a; Shyamala T, 2006, CHEM PHYS, V330, P469, DOI 10.1016-j.chemphys.2006.09.018; Singh TB, 2006, ANNU REV MATER RES, V36, P199, DOI 10.1146-annurev.matsci.36.022805.094757; Subuddhi U, 2006, PHOTOCH PHOTOBIO SCI, V5, P459, DOI 10.1039-b600009f; Wex B, 2006, J MATER CHEM, V16, P1121, DOI 10.1039-b512191d; Wex B, 2006, J PHYS CHEM A, V110, P13754, DOI 10.1021-jp065548s; Wex B, 2005, J ORG CHEM, V70, P4502, DOI 10.1021-jo048010w; Wex B, 2004, J ORG CHEM, V69, P2197, DOI 10.1021-jo035769j; Xia CJ, 2002, ORG LETT, V4, P2067, DOI 10.1021-ol025943a0
Altering the emission behavior with the turn of a thiophene ring: The photophysics of condensed ring systems of alternating benzenes and thiophenes
No full textSix aromatic compounds with embedded thiophenes differing in the number of rings (2-5) and thiophene orientation along the long axis of the molecule (syn, anti) were investigated. Photophysical properties, steady-state absorption, fluorescence, phosphorescence, lifetimes, quantum yields, and a comprehensive time-resolved spectroscopic analysis (femtosecond and nanosecond transient absorption spectroscopy) have been studied as a function of molecular structure. © 2006 American Chemical Society.Aaron JJ, 2002, J FLUORESC, V12, P231, DOI 10.1023-A:1016869002735; Abdel-Shafi AA, 2005, J PHOTOCH PHOTOBIO A, V172, P170, DOI 10.1016-j.photochem.2004.12.006; AGGARWAL N, 1979, ORG PREP PROCED INT, V11, P247; Becker RS, 1996, J PHYS CHEM-US, V100, P18683, DOI 10.1021-jp960852e; BEIMLING P, 1986, CHEM BER-RECL, V119, P3198, DOI 10.1002-cber.19861191025; Berlman I. B., 1971, HDB FLUORESCENCE SPE; BONNIER JM, 1970, J CHIM PHYS PCB, V67, P571; DAVYDOV SN, 1981, RUSS J PHYS CHEM, V55, P444; de Melo JS, 2003, J CHEM PHYS, V118, P1550, DOI 10.1063-1.1528604; de Melo JS, 2003, PHOTOCHEM PHOTOBIOL, V77, P121; Fichou D., 1999, HDB OLIGO POLYTHIOPH; FLICKER WM, 1976, J CHEM PHYS, V64, P1315, DOI 10.1063-1.432397; GENTILI PL, 2004, PHOTOCHEM PHOTOBIOL, V3, P881; Hadziioannou G, 2000, SEMICONDUCTING POLYM; Jabbarzadeh B, 1997, SPECTROSC LETT, V30, P1279, DOI 10.1080-00387019708006723; KIMURA O, 1988, Patent No. 63122727; Kunugi Y, 2004, J MATER CHEM, V14, P1367, DOI 10.1039-b401209g; Lap DV, 1997, J PHYS CHEM A, V101, P107, DOI 10.1021-jp961670n; Laquindanum JG, 1997, ADV MATER, V9, P36, DOI 10.1002-adma.19970090106; Luman CR, 2003, PHOTOCHEM PHOTOBIOL, V77, P510, DOI 10.1562-0031-8655(2003)0770510:LOFLIS2.0.CO;2; Meng H, 2005, J AM CHEM SOC, V127, P2406, DOI 10.1021-ja043189d; Merzlikine AG, 2004, PHOTOCH PHOTOBIO SCI, V3, P892, DOI 10.1039-b404580g; Murov S., 1993, HDB PHOTOCHEMISTRY; Nijegorodov N, 2001, SPECTROCHIM ACTA A, V57, P1449, DOI 10.1016-S1386-1425(00)00488-1; Pan HL, 2006, CHEM MATER, V18, P3237, DOI 10.1021-cm0602592; Perepichka IF, 2005, ADV MATER, V17, P2281, DOI 10.1002-adma.200500461; Perkampus H.-H, 1992, US VIS ATLAS ORGANIC; POMERANTZ M, 1994, MATER RES SOC SYMP P, V328, P227; Rentsch S, 1999, PHYS CHEM CHEM PHYS, V1, P1707, DOI 10.1039-a808617f; RYASHENTSEVA MA, 1988, IZV AKAD NAUK SSSR, V12, P2857; THYRION FC, 1973, J PHYS CHEM-US, V77, P1478, DOI 10.1021-j100631a002; TUROO N, 1991, MODERN MOL PHOTOCHEM; Wex B, 2006, J MATER CHEM, V16, P1121, DOI 10.1039-b512191d; Wex B, 2005, J ORG CHEM, V70, P4502, DOI 10.1021-jo048010w; Wex B, 2004, J ORG CHEM, V69, P2197, DOI 10.1021-jo035769j; WYNBERG H, 1970, J ORG CHEM, V35, P711, DOI 10.1021-jo00828a037; YOSHIDA S, 1994, J ORG CHEM, V59, P3077, DOI 10.1021-jo00090a027; ZANDER M, 1987, Z NATURFORSCH A, V42, P735; ZANDER M, 1985, Z NATURFORSCH A, V40, P497; ZANDER M, 1989, Z NATURFORSCH A, V44, P205119
ASH-WEX affects the distribution of events in the IMR-32 cell cycle.
No full text<p>IMR-32 cells were treated with 0.5% ASH-WEX and RA for 72 h (a). The evaluation of cell cycle progression was done by DNA staining by propidium iodide. The figure shows representative FACS profiles of the distribution of cells in G0/G1, S, and G2/M phases as analysed by FCS software. (b) Histogram represents percentage distribution of the cells in different phases (G0/G1, S, and G2/M) after ASH-WEX treatment as compared to control. (c) Flow cytometric examination of apoptosis, necrosis and cell viability-the Annexin V/PI assay. Diagrams show four subgroups of cells. Viable (Q1, annexin V-, PI-), early apoptotic (Q2, annexin V+, PI-), late apoptotic (Q3, annexin V+, PI+) and necrotic/damaged (Q4, annexin V-, PI+) are represented in different quadrants. (d) Histogram represents percentage distribution of the cells in different quadrants. “*” represents the statistical significant (p<0.05) difference between control and ASH-WEX treated groups.</p
Interplay between seismic fracture and aseismic creep in the Woodroffe Thrust, central Australia – Inferences for the rheology of relatively dry continental mid-crustal levels
No full textThe over 600 km long Woodroffe Thrust developed at lower to mid-crustal levels during the intracontinental Petermann Orogeny at ca. 560–520 Ma. Ductile deformation with a top-to-north shear sense was accommodated along a shallowly (≤30°) south-dipping surface. Metamorphic conditions during deformation are established along a 60 km N-S transect, providing an ideal framework for studying variation in microstructure and crystallographic preferred orientations with changing temperature (ca. 520–620 °C) and pressure/depth in dominantly dry felsic crust. In the Woodroffe Thrust mylonites, dynamic recrystallization of quartz was dominated by subgrain rotation, whereas feldspar underwent grain size reduction by neocrystallization. Differential stress, estimated from quartz grain size piezometry, decreases with increasing metamorphic grade (i.e., deeper structural levels), and indicates a long-term average strain rate of around 10−11–10−12 s−1. We propose a qualitative rheological model to explain the observed cyclic interplay between ductile shearing (mylonitization) and brittle fracturing (pseudotachylyte formation) in the relatively dry middle crust. The model involves the downward migration of earthquake ruptures from the overlying seismogenic zone, which transiently triggers seismic slip at mid-crustal levels
Geometry of a large-scale, low-angle, midcrustal thrust (Woodroffe Thrust, central Australia)
No full textThe Musgrave Block in central Australia exposes numerous large-scale mylonitic shear zones
developed during the intracontinental Petermann Orogeny around 560–520 Ma. The most prominent
structure is the crustal-scale, over 600 km long, E-W trending Woodroffe Thrust, which is broadly undulate but
generally dips shallowly to moderately to the south and shows an approximately top-to-north sense of
movement. The estimated metamorphic conditions of mylonitization indicate a regional variation from
predominantly midcrustal (circa 520–620°C and 0.8–1.1 GPa) to lower crustal (~650°C and 1.0–1.3 GPa) levels
in the direction of thrusting, which is also reflected in the distribution of preserved deformation
microstructures. This variation in metamorphic conditions is consistent with a south dipping thrust plane but
is only small, implying that a ≥60 km long N-S segment of the Woodroffe Thrust was originally shallowly
dipping at an average estimated angle of ≤6°. The reconstructed geometry suggests that basement-cored,
thick-skinned, midcrustal thrusts can be very shallowly dipping on a scale of many tens of kilometers in the
direction of movement. Such a geometry would require the rocks along the thrust to be weak, but field
observations (e.g., large volumes of syntectonic pseudotachylyte) argue for a strong behavior, at least
transiently. Localization on a low-angle, near-planar structure that crosscuts lithological layers requires a weak
precursor, such as a seismic rupture in the middle to lower crust. If this was a single event, the intracontinental
earthquake must have been large, with the rupture extending laterally over hundreds of kilometers
Weak and Slow, Strong and Fast: How Shear Zones Evolve in a Dry Continental Crust (Musgrave Ranges, Central Australia)
No full textThe strike-slip Davenport Shear Zone in Central Australia developed during the Petermann Orogeny (~550 Ma) in an intracontinental lower crustal setting under dry subeclogite facies conditions (~650 °C, 1.2 GPa). This approximately 5-km-wide mylonite zone encloses several large low-strain domains, allowing a detailed study of the initiation of shear zones and their progressive development. Quartzo-feldspathic gneisses and granitoids contain compositional layers, such as quartz-rich pegmatites, mafic bands, and dykes, which should preferentially localize viscous deformation if favorably orientated. This is not observed, except for long, continuous, and fine-grained dolerite dykes. Instead, many shear zones, typically a few millimeters to centimeters in width but extending for tens of meters, commonly exploited pseudotachylytes and are sometimes parallel to a network of little overprinted fractures. The recrystallized mineral assemblage in the sheared pseudotachylyte is similar to that in the host gneiss, without associated hydration due to fluid-rock interaction. Lack of localization in quartz-rich, coarser-grained (typically >50 μm) rocks compared to mafic dykes, precursor fractures, and pseudotachylytes implies that localization in the dry lower crust preferentially occurs along elongate, planar fine-grained layers. Transient high stress repeatedly initiated fractures, providing finer-grained, weaker, planar precursors that localized subsequent ductile shear zones. This intimate interplay between brittle and ductile deformation suggests a local source for lower crustal earthquakes, rather than downward migration of earthquakes from the shallower, usually more seismogenic part of the crust
Pseudotachylyte as field evidence for lower-crustal earthquakes during the intracontinental Petermann Orogeny (Musgrave Block, Central Australia)
No full textGeophysical evidence for lower continental crustal earthquakes in almost all collisional orogens is in conflict with the
widely accepted notion that rocks, under high grade conditions, should flow rather than fracture. Pseudotachylytes are
remnants of frictional melts generated during seismic slip and can therefore be used as an indicator of former seismogenic
fault zones. The Fregon Subdomain in Central Australia was deformed under dry sub-eclogitic conditions of
600–700 °C and 1.0–1.2 GPa during the intracontinental Petermann Orogeny (ca. 550 Ma) and
contains abundant pseudotachylyte. These pseudotachylytes are commonly foliated, recrystallized, and cross-cut by other
pseudotachylytes, reflecting repeated generation during ongoing ductile deformation. This interplay is interpreted as
evidence for repeated seismic brittle failure and post- to inter-seismic creep under dry lower-crustal
conditions. Thermodynamic modelling of the pseudotachylyte bulk composition gives the same PT conditions of shearing as
in surrounding mylonites. We conclude that pseudotachylytes in the Fregon Subdomain are a direct analogue of current
seismicity in dry lower continental crust
Inverted distribution of ductile deformation in the relatively "dry" middle crust across the Woodroffe Thrust, central Australia
No full textThrust fault systems typically distribute shear strain preferentially into the hanging wall rather than the footwall. The Woodroffe Thrust in the Musgrave Block of central Australia is a regional-scale example that does not fit this model. It developed due to intracontinental shortening during the Petermann Orogeny (ca. 560–520 Ma) and is interpreted to be at least 600 km long in its E–W strike direction, with an approximate top-to-north minimum displacement of 60–100 km. The associated mylonite zone is most broadly developed in the footwall. The immediate hanging wall was only marginally involved in the mylonitization process, as can be demonstrated from the contrasting thorium signatures of mylonites derived from the upper amphibolite facies footwall and the granulite facies hanging wall protoliths. Thermal weakening cannot account for such an inverse deformation gradient, as syn-deformational P –T estimates for the Petermann Orogeny in the hanging wall and footwall from the same locality are very similar. The distribution of pseudotachylytes, which acted as preferred nucleation sites for shear deformation, also cannot provide an explanation, since these fault rocks are especially prevalent in the immediate hanging wall. The most likely reason for the inverted deformation gradient across the Woodroffe Thrust is water-assisted weakening due to the increased, but still limited, presence of aqueous fluids in the footwall. We also establish a qualitative increase in the abundance of fluids in the footwall along an approx. 60 km long section in the direction of thrusting, together with a slight decrease in the temperature of mylonitization (ca. 100 ◦ C). These changes in ambient conditions are accompanied by a 6-fold decrease in thickness (from ca. 600 to 100 m) of the Woodroffe Thrust mylonitic zone
- …
