4,415 research outputs found
Mechanical properties of three-phase polyamide 6 nanocomposites
This work focus on the mechanical properties of three-phase nanocomposites using multiscale reinforcements. The influence of the nano-fillers content, as well as the temperature were studied. Polyamide-6 reinforced with short glass fibre 30 wt.% and with an addition of nanoclay (montmorillonite) and/or nanosilica (SiO2) were tested in order to characterise their tensile properties at room temperature and at 65oC just above the polyamide 6 glass transition temperature. SEM analysis were conducted on the fracture surface of the tensile bars. SEM investigations showed the importance of the interaction matrix/filler for the material behaviour. Our study also shows that the increase of OMMT percentage in polyamide-6/glass fibre composite made the material more brittle and had a negative effect on the tensile properties. Further, for the silica-based nanocomposites, an optimum was found for a nanofillers content of 1wt.%
Populism and the manufactured crisis of British neoliberalism: the case of Brexit
Using the case of Britain’s 2016 vote to leave the European Union, James Wood and Valentina Ausserladscheider challenge prevailing accounts explaining populism as political response to neoliberalism’s negative impact on voters. Using a descriptive analysis, they explain how the antagonistic ‘people’ vs. ‘elite’ relationship at the core of populism has been mobilised by opposing British political actors as a discursive frame to generate voter support for their own policies
Supermassive black hole pairs in clumpy galaxies at high redshift: delayed binary formation and concurrent mass growth
Massive gas-rich galaxy discs at host massive star-forming
clumps with typical baryonic masses in the range ~M which
can affect the orbital decay and concurrent growth of supermassive black hole
(BH) pairs. Using a set of high-resolution simulations of isolated clumpy
galaxies hosting a pair of unequal-mass BHs, we study the interaction between
massive clumps and a BH pair at kpc scales, during the early phase of the
orbital decay. We find that both the interaction with massive clumps and the
heating of the cold gas layer of the disc by BH feedback tend to delay
significantly the orbital decay of the secondary, which in many cases is
ejected and then hovers for a whole Gyr around a separation of 1--2 kpc. In the
envelope, dynamical friction is weak and there is no contribution of disc
torques: these lead to the fastest decay once the orbit of the secondary BH has
circularised in the disc midplane. In runs with larger eccentricities the delay
is stronger, although there are some exceptions. We also show that, even in
discs with very sporadic transient clump formation, a strong spiral pattern
affects the decay time-scale for BHs on eccentric orbits. We conclude that,
contrary to previous belief, a gas-rich background is not necessarily conducive
to a fast BH decay and binary formation, which prompts more extensive
investigations aimed at calibrating event-rate forecasts for ongoing and future
gravitational-wave searches, such as with Pulsar Timing Arrays and the future
evolved Laser Interferometer Space Antenna.Comment: Accepted by MNRA
Charge mobility of discotic mesophases: A multiscale quantum/classical study
A correlation is established between the molecular structure and charge
mobility of discotic mesophases of hexabenzocoronene derivatives by combining
electronic structure calculations, Molecular Dynamics, and kinetic Monte Carlo
simulations. It is demonstrated that this multiscale approach can provide an
accurate ab-initio description of charge transport in organic materials
Why stopping acid attacks is a matter of chemical weapons control
The use of acid as part of violent crime is apparently on the rise in the UK, and various efforts are being made to reverse what’s become a very disturbing trend
COVID-Keynesianism was a short-term crisis management tactic. Neoliberal policymaking is back
When major economies adopted Keynesian policies to deal with the COVID pandemic, the move was hailed as a Âreorientation of economic policymaking around a new policy paradigm. However, James Wood, Valentina Ausserladscheider, and Matthew Sparkes argue that rather than marking a permanent shift away from neoliberalism, Keynesian-style policies may have been a temporary form of economic crisis management, and neoliberal economic ideas have become re-established post-COVID
Discovery of Broad Soft X-ray Absorption Lines from the Quasar Wind in PDS 456
High resolution soft X-ray spectroscopy of the prototype accretion disk wind
quasar, PDS 456, is presented. Here, the XMM-Newton RGS spectra are analyzed
from the large 2013-2014 XMM-Newton campaign, consisting of 5 observations of
approximately 100 ks in length. During the last observation (hereafter OBS. E),
the quasar is at a minimum flux level and broad absorption line profiles are
revealed in the soft X-ray band, with typical velocity widths of km s. During a period of higher flux in the 3rd and 4th
observations (OBS. C and D, respectively), a very broad absorption trough is
also present above 1 keV. From fitting the absorption lines with models of
photoionized absorption spectra, the inferred outflow velocities lie in the
range . The absorption lines likely originate from He and H-like
neon and L-shell iron at these energies. Comparison with earlier archival data
of PDS 456 also reveals similar absorption structure near 1 keV in a 40 ks
observation in 2001, and generally the absorption lines appear most apparent
when the spectrum is more absorbed overall. The presence of the soft X-ray
broad absorption lines is also independently confirmed from an analysis of the
XMM-Newton EPIC spectra below 2 keV. We suggest that the soft X-ray absorption
profiles could be associated with a lower ionization and possibly clumpy phase
of the accretion disk wind, where the latter is known to be present in this
quasar from its well studied iron K absorption profile and where the wind
velocity reaches a typical value of 0.3.Comment: 44 pages, including 13 figures, accepted for publication in The
Astrophysical Journa
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