13,179 research outputs found
Thermomechanical properties of amorphous metallic tungsten-oxygen and tungsten-oxide coatings
In this work, we investigate the correlation between morphology, composition,
and the mechanical properties of metallic amorphous tungsten-oxygen and
amorphous tungsten-oxide films deposited by Pulsed Laser Deposition. This
correlation is investigated by the combined use of Brillouin Spectroscopy and
the substrate curvature method. The stiffness of the films is strongly affected
by both the oxygen content and the mass density. The elastic moduli show a
decreasing trend as the mass density decreases and the oxygen-tungsten ratio
increases. A plateaux region is detected in correspondence of the transition
between metallic and oxide films. The compressive residual stresses, moderate
stiffness and high local ductility that characterize compact amorphous
tungsten-oxide films make them promising for applications involving thermal or
mechanical loads. The coefficient of thermal expansion is quite high (i.e. 8.9
10 K), being strictly correlated to the amorphous
structure and stoichiometry of the films. Under thermal treatments they show a
quite low relaxation temperature (i.e. 450 K). They crystallize into the
monoclinic phase of WO starting from 670 K, inducing an increase
by about 70\% of material stiffness.Comment: The research leading to these results has also received funding from
the European Research Council Consolidator Grant ENSURE (ERC-2014-CoG No.
647554). The views and opinions expressed herein do not necessarily reflect
those of the European Commissio
Carbon-atom wires produced by nanosecond pulsed laser deposition in a background gas
Wires of sp-hybridized carbon atoms are attracting interest for both
fundamental aspects of carbon science and for their appealing functional
properties. The synthesis by physical vapor deposition has been reported to
provide sp-rich carbon films but still needs to be further developed and
understood in detail. Here the synthesis of carbon-atom wires (CAWs) has been
achieved by nanosecond pulsed laser deposition (PLD) expoliting the strong
out-of-equilibrium conditions occurring when the ablation plasma is confined in
a background gas. Surface Enhnaced Raman scattering (SERS) spectra of deposited
films indicates that CAWs are mixed with a mainly amorphous carbon in a
hybrid material. Optimal conditions for the deposition of sp-carbon
phase have been investigated by changing deposition parameters thus suggesting
basic mechanisms of carbon wires formation. Our proof-of-concept may open new
perspectives for the targeted fabrication of CAWs and structures.Comment: 15 pages 4 figure
Dilaton Gravity with a Non-minmally Coupled Scalar Field
We discuss the two-dimensional dilaton gravity with a scalar field as the
source matter. The coupling between the gravity and the scalar, massless, field
is presented in an unusual form. We work out two examples of these couplings
and solutions with black-hole behaviour are discussed and compared with those
found in the literature
Estimates of Cl atom concentrations and hydrocarbon kinetic reactivity in surface air at Appledore Island, Maine (USA), during International Consortium for Atmospheric Research on Transport and Transformation/Chemistry of Halogens at the Isles of Shoals
Average hydroxyl radical (OH) to chlorine atom (Cl·) ratios ranging from 45 to 119 were determined from variability‐lifetime relationships for selected nonmethane hydrocarbons (NMHC) in surface air from six different transport sectors arriving at Appledore Island, Maine, during July 2004. Multiplying these ratios by an assumed average OH concentration of 2.5 × 106 cm−3 yielded estimates of Cl· concentrations of 2.2 to 5.6 × 104 cm−3. Summed reaction rates of methane and more than 30 abundant NMHCs with OH and Cl· suggest that Cl· reactions increased the kinetic reactivity of hydrocarbons by 16% to 30% over that due to OH alone in air associated with the various transport sectors. Isoprene and other abundant biogenic alkenes were the most important hydrocarbon contributors after methane to overall kinetic reactivity
Relationship between blood remifentanil concentration and stress hormone levels during pneumoperitoneum in patients undergoing laparoscopic cholecystectomy
The effect of remifentanil on stress response to surgery is unclear. However, there are not clinical studies investigating the relationship between blood remifentanil concentrations and stress hormones. Therefore, the aim of the present study was to assess the association between blood remifentanil concentrations measured after pneumoperitoneum and cortisol (CORT) or prolactin (PRL) ratio (intraoperative/preoperative value), in patients undergoing laparoscopic cholecystectom
Development and validation of a measure of quality in playgroups: Playgroups environment rating scale
Playgroups are community-based services that bring together young children and their caregivers for the purpose of play and social activities. Preliminary evidence shows that playgroup impacts may be dependent on the quality of the playgroup. However, to date, there is no reliable and valid measure of playgroup quality. In this paper we describe the development and validation of the Playgroup Environment Rating Scale (PERS), a standardized observation measure designed to assess the quality of playgroups. PERS builds on traditional measures used to evaluate the quality of formal settings of early childhood education and care, while proposing to assess dimensions of quality specific to the nature of playgroups, namely complex interactions between several types of participants. After developing and testing the observation measure on 24 playgroup videos, we analyzed the psychometric properties. Results showed that the PERS had good interrater reliability, was internally consistent and shows a good preliminary factor structure. Tests for convergent and criterion-related validity also presented promising results. The process of design guaranteed that the PERS can be applied to different contexts of playgroups and may also be useful for informing service planning and practice. Further national and international validation will help replicate the validity of the scale.info:eu-repo/semantics/publishedVersio
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