3,217 research outputs found
Multimodal confined water dynamics in reverse osmosis polyamide membranes
While polyamide (PA) membranes are widespread in water purification and desalination by reverse osmosis, a molecular-level understanding of the dynamics of both confined water and polymer matrix remains elusive. Despite the dense hierarchical structure of PA membranes formed by interfacial polymerization, previous studies suggest that water diffusion remains largely unchanged with respect to bulk water. Here, we employ neutron spectroscopy to investigate PA membranes under precise hydration conditions, and a series of isotopic contrasts, to elucidate water transport and polymer relaxation, spanning ps-ns timescales, and Ă
-nm lengthscales. We experimentally resolve, for the first time, the multimodal diffusive nature of water in PA membranes: in addition to (slowed down) translational jump-diffusion, we observe a long-range and a localized mode, whose geometry and timescales we quantify. The PA matrix is also found to exhibit rotational relaxations commensurate with the nanoscale confinement observed in water diffusion. This comprehensive âdiffusion mapâ can anchor molecular and nanoscale simulations, and enable the predictive design of PA membranes with tuneable performance
Erratum: âPhysical apparatus parameters and model for vibrating tube densimeters at pressures to 140 MPa and temperatures to 473 Kâ [Rev. Sci. Instrum. 85, 095111 (2014)]
Microfluidic SAXS study of lamellar and multilamellar vesicle phases of linear sodium alkylbenzenesulfonate surfactant with intrinsic isomeric distribution
The structure and flow behaviour of a concentrated aqueous solution (45 w.t. %) of the ubiquitous linear sodium alkylbenzene sulfonate (NaLAS) surfactant is investigated by microfluidic small-angle X-ray scatterong (SAXS) at 70 â°C. NaLAS is an intrinsically complex mixture of over 20 surfactant molecules, presenting coexisting micellar (L1) and lamellar (Lα) phases. Novel microfluidic devices were fabricated to ensure pressure and thermal resistance, ability to handle viscous fluids, and low SAXS background. Polarized light optical microscopy showed that the NaLAS solution exhibits wall slip in microchannels, with velocity profiles approaching plug flow. Microfluidic SAXS demonstrated the structural spatial heterogeneity of the system with a characteristic lengthscale of 50 nL. Using a statistical flow-SAXS analysis we identified the micellar phase and multiple coexisting lamellar phases with a continuous distribution of d spacings between 37.5 Ă
- 39.5 Ă
. Additionally, we showed that the orientation of NaLAS lamellar phases is strongly affected by a single microfluidic constriction. The bilayers align parallel to the velocity field upon entering a constriction and perpendicular to it upon exiting. On the other hand, multi-lamellar vesicle phases are not affected under the same flow conditions. Our results demonstrate that, despite the compositional complexity inherent to NaLAS, microfluidic SAXS can rigorously elucidate its structure and flow response
Study of single muons with the Large Volume Detector at Gran Sasso Laboratory
The present study is based on the sample of about 3 mln single muons observed
by LVD at underground Gran Sasso Laboratory during 36500 live hours from June
1992 to February 1998. We have measured the muon intensity at slant depths from
3 km w.e. to 20 km w.e. Most events are high energy downward muons produced by
meson decay in the atmosphere. The analysis of these muons has revealed the
power index of pion and kaon spectrum: 2.76 \pm 0.05. The reminders are
horizontal muons produced by the neutrino interactions in the rock surrounding
LVD. The value of this flux is obtained. The results are compared with Monte
Carlo simulations and the world data.Comment: 13 pages, 2 figures, accepted for publication in "Physics of Atomic
Nuclei
A simulation tool for MRPC telescopes of the EEE project
The Extreme Energy Events (EEE) Project is mainly devoted to the study of the
secondary cosmic ray radiation by using muon tracker telescopes made of three
Multigap Resistive Plate Chambers (MRPC) each. The experiment consists of a
telescope network mainly distributed across Italy, hosted in different building
structures pertaining to high schools, universities and research centers.
Therefore, the possibility to take into account the effects of these structures
on collected data is important for the large physics programme of the project.
A simulation tool, based on GEANT4 and using GEMC framework, has been
implemented to take into account the muon interaction with EEE telescopes and
to estimate the effects on data of the structures surrounding the experimental
apparata.A dedicated event generator producing realistic muon distributions,
detailed geometry and microscopic behavior of MRPCs have been included to
produce experimental-like data. The comparison between simulated and
experimental data, and the estimation of detector resolutions is here presented
and discussed
Multiple Sclerosis in the Mount Etna Region: Possible Role of Volcanogenic Trace Elements
Background: Trace elements have been hypothesised to be involved in the pathogenesis of Multiple Sclerosis and volcanic
degassing is the major natural sources of trace elements. Both incidence of Multiple Sclerosis in Catania and volcanic activity
of Mount Etna have been significantly increased during the last 30 years. Due to prevailing trade winds direction, volcanic
gases from Etna summit craters are mostly blown towards the eastern and southern sectors of the volcano.
Objective: To evaluate the possible association between Multiple Sclerosis and exposure to volcanogenic trace elements.
Methods: We evaluated prevalence and incidence of Multiple Sclerosis in four communities (47,234 inhabitants) located in
the eastern flank and in two communities (52,210 inhabitants) located in the western flank of Mount Etna, respectively the
most and least exposed area to crater gas emissions.
Results: A higher prevalence was found in the population of the eastern flank compared to the population of the western
one (137.6/100,000 versus 94.3/100,000; p-value 0.04). We found a borderline significantly higher incidence risk during the
incidence study period (1980â2009) in the population of the eastern flank 4.6/100,000 (95% CI 3.1â5.9), compared with the
western population 3.2/100,000 (95% CI 2.4â4.2) with a RR of 1.41 (95% CI 0.97â2.05; p-value 0.06). Incidence risks have
increased over the time in both populations reaching a peak of 6.4/100,000 in the eastern flank and of 4.4/100.000 in the
western flank during 2000â2009.
Conclusion: We found a higher prevalence and incidence of Multiple Sclerosis among populations living in the eastern flank
of Mount Etna. According to our data a possible role of TE cannot be ruled out as possible co-factor in the MS pathogenesis.
However larger epidemiological study are needed to confirm this hypothesis.Publishede742596A. Monitoraggio ambientale, sicurezza e territorioJCR Journalope
A new Low Gain Avalanche Diode concept: the double-LGAD
This paper describes the new concept of the double-LGAD. The goal is to
increase the charge at the input of the electronics, keeping a time resolution
equal or better than a standard (single) LGAD; this has been realized by adding
the charges of two coupled LGADs while still using a single front-end
electronics. The study here reported has been done starting from single LGAD
with a thickness of 25 \textmu{m}, 35 \textmu{m} and 50 \textmu{m}.Comment: arXiv admin note: text overlap with arXiv:2208.0571
Multijet production in neutral current deep inelastic scattering at HERA and determination of α_{s}
Multijet production rates in neutral current deep inelastic scattering have been measured in the range of exchanged boson virtualities 10 5 GeV and â1 < η_{LAB}^{jet} < 2.5. Next-to-leading-order QCD calculations describe the data well. The value of the strong coupling constant α_{s} (M_{z}), determined from the ratio of the trijet to dijet cross sections, is α_{s} (M_{z}) = 0.1179 ± 0.0013 (stat.)_{-0.0046}^{+0.0028}(exp.)_{-0.0046}^{+0.0028}(th.)
The Extreme Energy Events HECR array: status and perspectives
The Extreme Energy Events Project is a synchronous sparse array of 52
tracking detectors for studying High Energy Cosmic Rays (HECR) and Cosmic
Rays-related phenomena. The observatory is also meant to address Long Distance
Correlation (LDC) phenomena: the network is deployed over a broad area covering
10 degrees in latitude and 11 in longitude. An overview of a set of preliminary
results is given, extending from the study of local muon flux dependance on
solar activity to the investigation of the upward-going component of muon flux
traversing the EEE stations; from the search for anisotropies at the sub-TeV
scale to the hints for observations of km-scale Extensive Air Shower (EAS).Comment: XXV ECRS 2016 Proceedings - eConf C16-09-04.
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