4,272 research outputs found
Probing neutrino magnetic moment and unparticle interactions with Borexino
We discuss the limits on the neutrino magnetic moment and hypothetical
interactions with a hidden unparticle sector, coming from the first neutrino
data release of the Borexino experiment. The observed spectrum in Borexino
depends weakly on the solar model used in the analysis, since most of the
signal comes from the mono-energetic 7Be neutrinos. This fact allows us to
calibrate the nu-e scattering cross section through the spectral shape. In this
way, we have derived a limit on the magnetic moment for the neutrinos coming
from the Sun (in which a nu_mu and nu_tau component is present): mu_nu<8.4E-11
mu_B (90%CL) which is comparable with those obtained from low energy reactor
experiments. Moreover, we improve the previous upper limit on magnetic moment
of the nu_tau by three orders of magnitude and the limit on the coupling
constant of the neutrino with a hidden unparticle sector.Comment: 16 pages, 3 figures. Some clarifications and references added.
Accepted for publication in Phys. Rev.
Pumping seawater from coastal aquifers for supplying desalination plants
The lack of water in the coastal areas demands an onerous search for an appropriate solution. One solution is that of water transfer from areas of surplus, but this is itself problematical. Technological developments have introduced the possibility of utilizing desalinated seawater as a drinking water source at a competitive price. Abstraction from coastal aquifers that are connected to the sea appears to be the cheapest means of supply. However, pumping poses some problems due to the corrosiveness of seawater. These problems include the difficulties of choosing suitable sites for the abstractions, drilling method, casing, filter pack, as well as the design of a monitoring system to assess aquifer behaviour as a result of the generally high exploitation rate. The 31 boreholes that have been drilled in the Andarax Delta near the city of Almeria are cited as an example of a real application
About the limits of microfiltration for the purification of wastewaters
In the past, microfiltration was widely used as a
pretreatment step for wastewater stream purification
purposes. Experiences performed during the last years
shows that microfiltration fails to maintain its
performances for longer period of times. Many case studies
demonstrate that the adoption of microfiltration leads to
the failure of the overall process; the severe fouling of the
microfiltration membranes leads to high operating costs
with the consequence to make the treatment of the
wastewater economically unfeasible. The boundary flux
concept is a profitable tool to analyze fouling issues in
membrane processes. The boundary flux value separates an
operating region characterized by reversible fouling
formation from irreversible one. Boundary flux values are
not content, but function of time, as calculated by the subboundary
fouling rate value. The knowledge of both
parameters may fully describe the membrane performances
in sub-boundary operating regimes. Many times, for
wastewater purification purposes, ultrafiltration
membranes appear to be suits better to the needs, even they
exhibit lower permeate fluxes compared to microfiltration.
Key to this choice is that ultrafiltration appears to resist
better to fouling issues, with a limited reduction of the
performances as a function of time. In other words, it
appears that ultrafiltration exhibit higher boundary flux
values and lower sub-boundary fouling rates. In this work,
after a brief introduction to the boundary flux concept, for
many different wastewater streams (more than 20,
produced by the most relevant industries in food,
agriculture, manufacture, pharmaceutics), the boundary
flux and sub-boundary fouling rate values of different
microfiltration and ultrafiltration membranes will be
discussed and compared. The possibility to successfully
use microfiltration as a pretreatment step strongly depends
on the feedstock characteristics and, in detail, on the
particle size of the suspended matter. In most cases,
microfiltration demonstrates to be technically unsuitable
for pretreatment purposes of many wastewater streams; as
a consequence, the adoption of microfiltration pushes
operators to exceed boundary flux conditions, therefore
triggering severe fouling, that leads to economic
unfeasibility of the process in long terms
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