12,620 research outputs found
Bouncing solutions from generalized EoS
We present an exact analytical bouncing solution for a closed universe filled
with only one exotic fluid with negative pressure, obeying a Generalized
Equations of State (GEoS) of the form , where
, and are constants. In our solution and
and is kept as a free parameter. For particular values of
the initial conditions, we obtain that our solution obeys Null Energy Condition
(NEC), which allows us to reinterpret the matter source as that of a real
scalar field, , with a positive kinetic energy and a potential .
We compute numerically the scalar field as a function of time as well as its
potential , and find an analytical function for the potential that
fits very accurately with the numerical results obtained. The shape of this
potential can be well described by a Gaussian-type of function, and hence,
there is no spontaneous symmetry minimum of . We further show that the
bouncing scenario is structurally stable under small variations of the
parameter , such that a family of bouncing solutions can be find
numerically, in a small vicinity of the value .Comment: 12 pages, 12 figure
nZVI particles production for the remediation of soil and water polluted by inorganic Lead
The present study deals with experiments of Pb removal by
nano-Zero Valent Iron (nZVI) in aqueous solution and in
soil. Synthetic Pb aqueous solutions were treated by nZVI,
at a fixed Pb concentration of 100 mg L-1
, varying
nanoparticles initial concentration in the range between 27
and 270 mg nZVI L-1
. A kinetic study was carried out: Pb
adsorption followed a first order kinetic, and half life times
between 11 and 26.66 min were determined. Soil samples
were first characterized, and Pb speciation and
concentration by sequential extractions was determined.
Adsorption tests were then carried out at three selected
amounts of nZVI, to allow Pb stabilization in the soil
matrix. To evaluate the treatment efficiency, sequential
extractions were also performed on the treated samples
Hexavalent chromium reduction in manganese-rich soils by ZVI nanoparticles: the influence of natural organic matter and manganese oxides
Hexavalent chromium reduction by nano Zero-Valent Iron
(nZVI) has been proved fast and efficient, mainly due to
nanoparticles large specific surface area and high chemical
reactivity. In this work the influence of natural organic
matter and manganese oxide was investigated, through a
set of experimental tests carried out on a real polluted soils
naturally rich in manganese. Soil samples were
characterized in terms of initial concentration of Cr,
Cr(VI), Mn, pH, and TOC and three different nZVI
solutions were used (120, 360 and 600 mg nZVI L-1
) for
the treatment. At selected interval times (0, 5, 10, 15, 30,
60, 120 min) a slurry sample was filtered and Cr(VI)
residual concentration and pH were measured. The same
procedure was carried out on an artificial spiked soil,
characterized by a similar TOC and poor of Mn.
Furthermore the two soils were mixed with different
amounts of leonardite, to evaluate the influence of NOM
on treatment efficiency
Continuous production of KNO3 nanosalts for the fertilization of soil by means of a Spinning Disk Reactor
In this study the production of high soluble material
nanoparticles was successfully performed by means of a
spinning disk reactor (SDR). This result was possible due
to the use of a potassium nitrate saturated solution, which
was continuously recycled back to the reactor after
removal of the produced solid nanoparticles.
Several process configurations were checked. It appears to
be mandatory that the recycled saturated solution must be
free of residual nanoparticles since their presence would
lead to heterogeneous nucleation. In this respect, a small
amount of nitric acid was added to the stream to permit the
residual nanoparticle dissolution. Moreover, a spiral
wounded piping system was developed in order to increase
both the contact time and the mixing condition of the
saturated solution with the added acid before entering the
SD
Entanglement production by quantum error correction in the presence of correlated environment
We analyze the effect of a quantum error correcting code on the entanglement
of encoded logical qubits in the presence of a dephasing interaction with a
correlated environment. Such correlated reservoir introduces entanglement
between physical qubits. We show that for short times the quantum error
correction interprets such entanglement as errors and suppresses it. However
for longer time, although quantum error correction is no longer able to correct
errors, it enhances the rate of entanglement production due to the interaction
with the environment.Comment: 7 pages, 3 figures, published versio
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