6,286 research outputs found
Nanoparticles in explosives detection – the state-of-the-art and future directions
No abstract available
Two-Parameter Differential Calculus on the h-Exterior Plane
We construct a two-parameter covariant differential calculus on the quantum
-exterior plane. We also give a deformation of the two-dimensional fermionic
phase space.Comment: 7 page
Cross-waves induced by the vertical oscillation of a fully immersed vertical plate
Capillary waves excited by the vertical oscillations of a thin elongated
plate below an air-water interface are analyzed using time-resolved
measurements of the surface topography. A parametric instability is observed
above a well defined acceleration threshold, resulting in a so-called
cross-wave, a staggered wave pattern localized near the wavemaker and
oscillating at half the forcing frequency. This cross-wave, which is stationary
along the wavemaker but propagative away from it, is described as the
superposition of two almost anti-parallel propagating parametric waves making a
small angle of the order of with the wavemaker edge. This
contrasts with the classical Faraday parametric waves, which are exactly
stationnary because of the homogeneity of the forcing. Our observations suggest
that the selection of the cross-wave angle results from a resonant mechanism
between the two parametric waves and a characteristic length of the surface
deformation above the wavemaker.Comment: to appear in Physics of Fluid
Reconnection of superfluid vortex bundles
Using the vortex filament model and the Gross Pitaevskii nonlinear
Schroedinger equation, we show that bundles of quantised vortex lines in helium
II are structurally robust and can reconnect with each other maintaining their
identity. We discuss vortex stretching in superfluid turbulence and show that,
during the bundle reconnection process, Kelvin waves of large amplitude are
generated, in agreement with the finding that helicity is produced by nearly
singular vortex interactions in classical Euler flows.Comment: 10 pages, 7 figure
An Account of Clitics in Shabaki with Reference to Wackernagels Law
In this paper the behavior of clitics in Shabaki a northwestern Indo-Iranian language spoken in Nineveh plains in Iraq is discussed in detail with respect to forms and distributions and much more interestingly with respect to sensitivity to Wackernagel s Law The paper also addresses clitic doubling clustering and climbing which may be considered the peculiar defining features of Shabaki They could be added to nouns pronouns verbs prepositions and other clitics Shabaki is a language with multiple cliticization and is surprisingly complicated with respect to this phenomenon It has an intricate system of clitics which include subject pronominal clitics object pronominal clitics dative and accusative possessive pronominal clitics demonstrative pronoun clitics ezafe clitics diminutive clitics additive clitics aspectual clitics tense clitics copular clitics and negative clitic
Superfluid 4He dynamics beyond quasiparticle excitations
The dynamics of superfluid 4He at and above the Landau quasiparticle regime
is investigated by high precision inelastic neutron scattering measurements of
the dynamic structure factor. A highly structured response is observed above
the familiar phonon-maxon-roton spectrum, characterized by sharp thresholds for
phonon-phonon, maxon-roton and roton-roton coupling processes. The experimental
dynamic structure factor is compared to the calculation of the same physical
quantity by a Dynamic Many-body theory including three-phonon processes
self-consistently. The theory is found to provide a quantitative description of
the dynamics of the correlated bosons for energies up to about three times that
of the Landau quasiparticles.Comment: 5 pages, 3 figure
Sensitive and specific detection of explosives in solution and vapour by surface-enhanced Raman spectroscopy on silver nanocubes
Surface-enhanced Raman spectroscopy (SERS) has been widely utilised as a sensitive analytical technique
for the detection of trace levels of organic molecules. The detection of organic compounds in the gas
phase is particularly challenging due to the low concentration of adsorbed molecules on the surface of the
SERS substrate. This is particularly the case for explosive materials, which typically have very low vapour
pressures, limiting the use of SERS for their identification. In this work, silver nanocubes (AgNCs) were developed
as a highly sensitive SERS substrate with very low limit-of-detection (LOD) for explosive materials
down to the femtomolar (10−15 M) range. Unlike typical gold-based nanostructures, the AgNCs were found
suitable for the detection of both aromatic and aliphatic explosives, enabling detection with high specificity
at low concentration. SERS studies were first carried out using a model analyte, Rhodamine-6G (Rh-6G), as
a probe molecule. The SERS enhancement factor was estimated as 8.71 × 1010 in this case. Further studies
involved femtomolar concentrations of 2,4-dinitrotoluene (DNT) and nanomolar concentrations of 1,3,5-trinitroperhydro-1,3,5-triazine
(RDX), as well as vapour phase detection of DNT
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