206 research outputs found
Thinking deep. Acting on top. Underground built heritage and its fringe as a community catalyst for local sustainable development : Exploratory cases from poland and greece
Underground Built Heritage (UBH) is a distinct class of cultural heritage providing a focal point for community pride and engagement to become a springboard for local sustainable development (LSD). This research aims to articulate how local UBH and its fringe serve as a facilitator of communal identity to mobilize community care towards social and economic development with less involvement from the state and the market actors. For this purpose, local (and less-conspicuous) cases of UBH are employed in Warsaw, Poland, and Volos, Greece, indicating the power of UBH to connect and engage local communities with places, triggering a momentum for a truly bottom-up action that pays less attention to market considerations and state support. The studied UBH sites have been discussed according to an established common framework, dealing with five main issues: (a) general context and status, (b) history, (c) users and management, (d) ecosystem services, and (e) introduction of the paradigm of living labs. The analysis was based on a thorough literature review and complemented by field observations and interviews. The results provide evidence for UBH as a potential facilitator of social and economic development. The case studies in Poland and Greece showed that local actors were involved in activities and social networks of tacit knowledge, generating community building to reinforce bottom-up activities in contact with UBH
Raman spectra of MgB2 at high pressure and topological electronic transition
Raman spectra of the MgB2 ceramic samples were measured as a function of
pressure up to 32 GPa at room temperature. The spectrum at normal conditions
contains a very broad peak at ~590 cm-1 related to the E2g phonon mode. The
frequency of this mode exhibits a strong linear dependence in the pressure
region from 5 to 18 GPa, whereas beyond this region the slope of the
pressure-induced frequency shift is reduced by about a factor of two. The
pressure dependence of the phonon mode up to ~ 5GPa exhibits a change in the
slope as well as a "hysteresis" effect in the frequency vs. pressure behavior.
These singularities in the E2g mode behavior under pressure support the
suggestion that MgB2 may undergo a pressure-induced topological electronic
transition.Comment: 2 figure
Pressure screening in the interior of primary shells in double-wall carbon nanotubes
The pressure response of double-wall carbon nanotubes has been investigated
by means of Raman spectroscopy up to 10 GPa. The intensity of the radial
breathing modes of the outer tubes decreases rapidly but remain observable up
to 9 GPa, exhibiting a behavior similar (but less pronounced) to that of
single-wall carbon nanotubes, which undergo a shape distortion at higher
pressures. In addition, the tangential band of the external tubes broadens and
decreases in amplitude. The corresponding Raman features of the internal tubes
appear to be considerably less sensitive to pressure. All findings lead to the
conclusion that the outer tubes act as a protection shield for the inner tubes
whereas the latter increase the structural stability of the outer tubes upon
pressure application.Comment: PDF with 15 pages, 3 figures, 1 table; submitted to Physical Review
Superconductivity: Exotic Commonalities in Phase and Mode
Recent muon and neutron experiments on the new FeAs-based superconductors
revealed phase diagrams characterized by first-order evolution from
antiferromagnetic to superconducting states, and an inelastic magnetic
resonance mode whose energy scales as . These features
exhibit striking commonalities with cuprate, backyball, organic, and
heavy-fermion superconductors as well as superfluid He.Comment: 4 pages, 2 figures, original version of News and Views for Nature
Materials submitted on Feb. 8, 2009; revised version will appear as Nature
Materials 8 (April, 2009) 253-25
muSR study of carbon-doped MgB2 superconductors
The evolution of the superconducting properties of the carbon-doped MgB2
superconductors, MgB(2-x)Cx (x= 0.02, 0.04, 0.06) have been investigated by the
transverse-field muon spin rotation (TF-muSR) technique. The low-temperature
depolarisation rate, sigma(0) at 0.6 T which is proportional to the second
moment of the field distribution of the vortex lattice decreases monotonically
with increasing electron doping and decreasing Tc. In addition, the temperature
dependence of sigma(T) has been analysed in terms of a two-gap model. The size
of the two superconducting gaps decreases linearly as the carbon content
increases, while the doping effect is more pronounced for the smaller gap
related to the 3D pi-sheets of the Fermi surface.Comment: 7 pages, 2 Figures, 1 Table, Europhys. Lett. in pres
Elucidation of One Step Synthesis of PEGylated CuFe Bimetallic Nanoparticles. Antimicrobial Activity of CuFe@PEG vs Cu@PEG
There is a growing field of research on the physicochemical properties of bimetallic nanoparticles (BMNPs) and their potential use in different applications. Meanwhile, their antimicrobial activity is scarcely reported, although BMNPs can potentially achieve unique chemical transformations and synergetic effects can be presented. Towards this direction a reproducible simple hybrid polyol process under moderate temperature solvothermal conditions has been applied for the isolation of non-oxide contaminated bimetallic CuFe nanoparticles (NPs). 1,2-propylene glycol (PG), tetraethylene glycol (TEG) and polyethylene glycol (PEG 8000), that exhibit different physicochemical properties, have been utilized to regulate the size, structure, composition and the surface chemistry of NPs. The BMNPs were found to be of small crystalline size, 30–45 nm, and high hydrophilicity, different wt% percentage of organic coating and variable hydrodynamic size and surface charge. The antimicrobial activity of the BMNPs was evaluated against the bacterial strains B. subtilis, E. coli and fungus S. cerevisiae. The IC50 values for CuFe NPs were found significantly lower compared with Cu NPs of the same size, revealing an enhancement in the antimicrobial activity when iron and copper coexist in the crystal structure. The reactive oxygen species (ROS) production was measured intracellularly and extracellularly by the nitroblue tetrazolium assay in the fungal cultures. No extracellular ROS were measured suggesting that both CuFe and Cu NPs enter the fungal cells during the incubation, also verified by optical imaging of the fungal cells in the presence of NPs. Higher ROS concentrations were generated intracellularly for CuFe NPs supporting different red/ox reaction mechanisms
Report of the Biological Data Analysis Workshop of the European Marine Observation and Data Network (EMODnet)
B NMR study of pure and lightly carbon doped MgB superconductors
We report a B NMR line shape and spin-lattice relaxation rate
() study of pure and lightly carbon doped MgBC for
, 0.02, and 0.04, in the vortex state and in magnetic field of 23.5 kOe.
We show that while pure MgB exhibits the magnetic field distribution from
superposition of the normal and the Abrikosov state, slight replacement of
boron with carbon unveils the magnetic field distribution of the pure Abrikosov
state. This indicates a considerable increase of with carbon doping
with respect to pure MgB. The spin-lattice relaxation rate
demonstrates clearly the presence of a coherence peak right below in pure
MgB, followed by a typical BCS decrease on cooling. However, at
temperatures lower than K strong deviation from the BCS behavior is
observed, probably from residual contribution of the vortex dynamics. In the
carbon doped systems both the coherence peak and the BCS temperature dependence
of weaken, an effect attributed to the gradual shrinking of the
hole cylinders of the Fermi surface with electron doping.Comment: 8 pages, 6 figures, submitted to Phys. Rev.
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