1,447 research outputs found
Design of Wireless Sensor Nodes for Structural Health Monitoring applications
Enabling low-cost distributed monitoring, wireless sensor networks represents an interesting solution for the implementation of
structural health monitoring systems. This work deals with the design of wireless sensor networks for health monitoring of civil
structures, specifically focusing on node design in relation to the requirements of different structural monitoring application classes.
Design problems are analysed with specific reference to a large-scale experimental setup (the long-term structural monitoring of
the Basilica S. Maria di Collemaggio, L’Aquila, Italy). Main limitations emerged are highlighted, and adopted solution strategies
are outlined, both in the case of commercial sensing platform and of full custom solutions
Thermomechanical properties of graphene: valence force field model approach
Using the valence force field model of Perebeinos and Tersoff [Phys. Rev. B
{\bf79}, 241409(R) (2009)], different energy modes of suspended graphene
subjected to tensile or compressive strain are studied. By carrying out Monte
Carlo simulations it is found that: i) only for small strains () the total energy is symmetrical in the strain, while it
behaves completely different beyond this threshold; ii) the important energy
contributions in stretching experiments are stretching, angle bending,
out-of-plane term and a term that provides repulsion against
misalignment; iii) in compressing experiments the two latter terms increase
rapidly and beyond the buckling transition stretching and bending energies are
found to be constant; iv) from stretching-compressing simulations we calculated
the Young modulus at room temperature 350\,N/m, which is in good
agreement with experimental results (340\,N/m) and with ab-initio
results [322-353]\,N/m; v) molar heat capacity is estimated to be
24.64\,J/molK which is comparable with the Dulong-Petit value,
i.e. 24.94\,J/molK and is almost independent of the strain; vi)
non-linear scaling properties are obtained from height-height correlations at
finite temperature; vii) the used valence force field model results in a
temperature independent bending modulus for graphene, and viii) the Gruneisen
parameter is estimated to be 0.64.Comment: 8 pages, 5 figures. To appear in J. Phys.: Condens. Matte
Grounding co-writing: An analysis of the theoretical basis of a new approach in mental health care
This contribution aims to highlight the theoretical and epistemological premises of the
co-writing experience, a practice where a clinician and a patient are mutually engaged
in jointly or collaboratively writing a narrative related to the patient’s experience.
Unlike a typical set of therapeutic techniques, co-writing is based on sharing perspectives and meanings about the experience of crisis, recovery, and the therapeutic
process. The paper identifies and briefly describes four non-clinical epistemological
paradigms on which it is grounded: ethnography, values-based practice, narrative
care, and phenomenology. Although they differ in several ways, at the same time,
they seem to share some common features that the paper investigates and comments.
For clinicians, nurses, researchers and Mental Health Service managers, attention
to the users and to the improvement of their active roles represents not only a strategy for the empowerment of results, but also the access door to a different perspective which relies on a renewed conceptualization of the mental disease nature that
may lead to overcoming the epistemic asymmetry between the ‘expert’ and the ‘other’
in favor of intersubjective dialogue
Phase-Insensitive Scattering of Terahertz Radiation
The nonlinear interaction between Near-Infrared (NIR) and Terahertz pulses is
principally investigated as a means for the detection of radiation in the
hardly accessible THz spectral region. Most studies have targeted second-order
nonlinear processes, given their higher efficiencies, and only a limited number
have addressed third-order nonlinear interactions, mainly investigating
four-wave mixing in air for broadband THz detection. We have studied the
nonlinear interaction between THz and NIR pulses in solid-state media
(specifically diamond), and we show how the former can be frequency-shifted up
to UV frequencies by the scattering from the nonlinear polarisation induced by
the latter. Such UV emission differs from the well-known electric-field-induced
second harmonic (EFISH) one, as it is generated via a phase-insensitive
scattering, rather than a sum- or difference-frequency four-wave-mixing
process
Non-linear unbalanced Bessel beams: Stationary conical waves supported by nonlinear losses
Nonlinear losses accompanying Kerr self-focusing substantially impacts the
dynamic balance of diffraction and nonlinearity, permitting the existence of
localized and stationary solutions of the 2D+1 nonlinear Schrodinger equation
which are stable against radial collapse. These are featured by linear conical
tails that continually refill the nonlinear, central spot. An experiment shows
that the discovered solution behaves as strong attractor for the self-focusing
dynamics in Kerr media.Comment: 4 pages, 2 figures; experimental verification adde
Physical properties of single-crystalline fibers of the colossal-magnetoresistance manganite La0.7Ca0.3MnO3
We have grown high-quality single crystals of the colossal-magnetoresistance
(CMR) material La0.7Ca0.3MnO3 by using the laser heated pedestal growth (LHPG)
method. Samples were grown as fibers of different diameters, and with lengths
of the order of centimeters. Their composition and structure were verified
through X-ray diffraction, scanning electron microcopy with EDX (Energy
Dispersive X-ray Analysis) and by Rietveld analysis. The quality of the
crystalline fibers was confirmed by Laue and EBSD (Electron Backscatter
Diffraction) patterns. Rocking curves performed along the fiber axis revealed a
half-height width of 0.073 degrees. The CMR behavior was confirmed by
electrical resistivity and magnetization measurements as a function of
temperature.Comment: 11 pages (including 3 figures); to appear in Appl. Phys. Let
Biogenic silver nanoparticles: Understanding the antimicrobial mechanism using Confocal Raman Microscopy
The antimicrobial properties of silver nanoparticles (AgNPs) have made them ubiquitous in a number of real-world industrial applications; however, the antimicrobial mode of action of biogenic AgNPs is not entirely understood. The use of Raman spectroscopy can provide molecular fingerprint information on various chemical and biochemical components in complex systems like microbial cultures, without the need for any complex sample pre-treatment. Consequently, the antimicrobial mechanism of AgNPs can be inferred through morphological and compositional changes of microbial cells that are monitored via changes in Raman band profiles. Here we show the synthesis of biogenic AgNPs using the extracellular cell-free filtrates of Penicillium expansum. The antimicrobial activity of the Penicillium expansum synthesized silver nanoparticles (hereafter PeNPs) was evaluated and the interactions between the nanoparticles and Escherichia coli were studied using Transmission Electron Microscopy (TEM) and Environmental Scanning Electron Microscopy (ESEM), showing the attachment of PeNPs to the surface of the bacteria and rupture of the bacterial cell membrane. Importantly, we show how Confocal Raman Microscopy can be used as an innovative approach to study the antimicrobial mechanisms, the results of which confirm that the PeNPs induce damage to bacterial and fungal cells, resulting in critical changes to polysaccharides, lipids, proteins and nucleic acids
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