Search results for "Glas"
showing 10 items of 1259 documents
Solidification behavior of the theta system 2-propanol/poly(n-butyl methacrylate) I. Influences of thermoreversible gelation on stationary flow
1994
Zero shear viscosities, η0, were determined by means of a magnetoviscometer for melts of poly(n-butyl methacrylate) (M = 8.7 to 450 kg/mol, T =53.5 to 200°C) and for concentrated solutions of the highest molecular weight sample in isopropanol (T = 34.8 to 131.5 °C). Master curves can be constructed in both cases if the reference temperature is set proportional to the gelation temperature of the particular fluid. Special intersegmental interactions (eventually leading to thermoreversible gelation) can above all be felt in η0 (T) and in M c , the critical molecular weight determined in plots of log η0 vs. log M. As the temperature is lowered, the behavior changes from WLF to Arrhenius, and M …
Dipolar and orientational glass formation in two-dimensional films of CO mixtures
2002
Heat-capacity and dielectric measurements have been performed to study orientational and dipolar order and disorder phenomena in submonolayer films of CO and binary mixtures of CO physisorbed on graphite and boron nitride (BN). With both methods transitions to quadrupolar and dipolar ordered low-temperature phases have been found for pure CO. Calorimetric measurements revealed that the dipolar transition of CO on graphite belongs to the universality class of the two-dimensional (2D) Ising model. It will be shown that in dilute mixtures of CO with CH 4 molecules a dramatic suppression of this phase transition occurs. This effect turned out to be much stronger than that previously observed in…
Fragmentation of polycarbonate macroinitiators in solution and in the bulk state
1990
The diphenylethane initiator 3,4-diethyl-3,4-(p-methoxyphenyl)-hexane (T–OCH3) was synthesized. By cocondensation of bisphenol A or C and the bisphenol derivative (“T”) of T–OCH3 with phosgene, polycarbonate macroinitiators PC(TxA1-x) and PC(TxC1-x) with different compositions x were made. The thermal fragmentation of T–OCH3 and the copolycarbonates was investigated with and without a radical scavenger both in solution and in the bulk state. The primary dissociation of T–OCH3 is a monomolecular Arrhenius process with a characteristic temperature of T* (τ = 1h) = 140°C (τ: average life time of the intact molecule). When the radicals are not intercepted, the dissociation is excessively revert…
Diverging Collectives: Artist-Run Spaces versus Warehouse Shows Comparative models of art production and cooperation among young British artists
2017
The paper addresses the case of artist-run spaces and warehouse shows in the United Kingdom between the 1980s and 1990s, a time when autonomous group shows and independent artist collectives sprawled particularly thanks to the engagement of a new generation of artists, among whom were found later celebrities such as Damien Hirst and Douglas Gordon. It will be argued that both artist-run spaces and warehouse shows were feasible solutions for young authors against art market barriers and economic crisis, although they held structural and organisational differences that would affect aesthetic outcomes and present art history with a shift in the model of the art collective.
Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
2017
On 2017 August 17, the gravitational-wave event GW170817 was observed by the Advanced LIGO and Virgo detectors, and the gamma-ray burst (GRB) GRB 170817A was observed independently by the Fermi Gamma-ray Burst Monitor, and the Anticoincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory. The probability of the near-simultaneous temporal and spatial observation of GRB 170817A and GW170817 occurring by chance is $5.0\times 10^{-8}$. We therefore confirm binary neutron star mergers as a progenitor of short GRBs. The association of GW170817 and GRB 170817A provides new insight into fundamental physics and the origin of short gamma-ray bursts. We use the ob…
Multifrequency Studies of the Peculiar Quasar 4C +21.35 during the 2010 Flaring Activity
2014
著者人数: 290名
An Indication of Anisotropy in Arrival Directions of Ultra-high-energy Cosmic Rays through Comparison to the Flux Pattern of Extragalactic Gamma-Ray …
2018
A new analysis of the dataset from the Pierre Auger Observatory provides evidence for anisotropy in the arrival directions of ultra-high-energy cosmic rays on an intermediate angular scale, which is indicative of excess arrivals from strong, nearby sources. The data consist of 5514 events above 20 EeV with zenith angles up to 80 deg recorded before 2017 April 30. Sky models have been created for two distinct populations of extragalactic gamma-ray emitters: active galactic nuclei from the second catalog of hard Fermi-LAT sources (2FHL) and starburst galaxies from a sample that was examined with Fermi-LAT. Flux-limited samples, which include all types of galaxies from the Swift-BAT and 2MASS …
Multiple accelerated particle populations in the Cygnus Loop with Fermi-LAT
2021
The Cygnus Loop (G74.0-8.5) is a very well-known nearby supernova remnant (SNR) in our Galaxy. Thanks to its large size, brightness, and angular offset from the Galactic plane, it has been studied in detail from radio to $\gamma$-ray emission. The $\gamma$ -rays probe the populations of energetic particles and their acceleration mechanisms at low shock speeds. We present an analysis of the $\gamma$-ray emission detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope over 11 years in the region of the Cygnus Loop. We performed detailed morphological and spectral studies of the $\gamma$-ray emission toward the remnant from 100 MeV to 100 GeV and compared it with X-ra…
Bias correction of dynamically downscaled precipitation to compute soil water deficit for explaining year-to-year variation of tree growth over north…
2017
This paper documents the accuracy of a post-correction method applied to precipitation regionalized by the Weather Research and Forecasting (WRF) Regional Climate Model (RCM) for improving simulated rainfall and feeding impact studies. The WRF simulation covers Burgundy (northeastern France) at a 8-km resolution and over a 20-year long period (1989–2008). Previous results show a strong deficiency of the WRF model for simulating precipitation, especially when convective processes are involved. In order to reduce such biases, a Quantile Mapping (QM) method is applied to WRF-simulated precipitation using the mesoscale atmospheric analyses system SAFRAN («Système d'Analyse Fournissant des Rense…
MZ-35, a new layered pentasil borosilicate synthesized in the presence of large alkali cations
2013
Abstract A new layered borosilicate has been synthesized in the presence of cesium and sodium cations and its structure has been solved by a combination of automated diffraction tomography (ADT) and X-ray powder diffraction (XRPD). MZ-35 has a composition NaCs 2 [BSi 7 O 16 (OH) 2 ](OH) 2 ·4H 2 O and features space group P-4m2. The unusually small unit cell ( a 7.3081 A, c 10.7520 A) is shared by two random-stacked configurations of the structure: a network of connected pentasil units related to the layer of RUB-18 and a bidimensional checkerboard of intersecting ladders of 4-membered rings. The two configurations are related by the simple face-sharing inversion of a hydroxyl-bearing tetrah…