324 research outputs found
Effect of ELF e.m. fields on metalloprotein redox-active sites
The peculiarity of the distribution and geometry of metallic ions in enzymes
pushed us to set the hypothesis that metallic ions in active-site act like tiny
antennas able to pick up very feeble e.m. signals. Enzymatic activity of Cu2+,
Zn2+ Superoxide Dismutase (SOD1) and Fe2+ Xanthine Oxidase (XO) has been
studied, following in vitro generation and removal of free radicals. We
observed that Superoxide radicals generation by XO is increased by a weak field
having the Larmor frequency fL of Fe2+ while the SOD1 kinetics is sensibly
reduced by exposure to a weak field having the frequency fL of Cu2+ ion.Comment: 18 pages, 4 figure
Dielectric permittivity of aqueous solutions of electrolytes probed by THz time-domain and FTIR spectroscopy
We have measured the dielectric permittivity of pure water and aqueous chlorides solutions in the range 0.2-1.5THz. We considered the relaxation spectral function as the weighted sum of two independent single-parameter Debye functions. Such an approach allowed to drastically reduce the number of the parameters used in the fit which we set only by physical considerations. The resulting functions allow to fit the experimental data for pure water and solutions of LiCl, KCl, NaCl, and CsCl and to predict the excess response on the high frequency side of the relaxation without “ad hoc” corrective terms
Orbital-dependent electron dynamics in Fe-pnictide superconductors
We report on orbital-dependent quasiparticle dynamics in EuFeAs, a
parent compound of Fe-based superconductors and a novel way to experimentally
identify this behavior, using time- and angle-resolved photoelectron
spectroscopy across the spin density wave transition. We observe two different
relaxation time scales for photo-excited d/d and d
electrons. While d/d electrons relax faster through the
electron-electron scattering channel, showing an itinerant character, d
electrons form a quasi-equilibrium state with the lattice due to their
localized character, and the state decays slowly. Our findings suggest that
electron correlation in Fe-pnictides is an important property, which should be
taken into careful account when describing the electronic properties of both
parent and electron-doped compounds, and therefore establish a strong
connection with cuprates
Healthcare Associated Infections. educational intervention by "Adult Learning" in an Italian teaching hospital
An educational intervention for HAI prevention based on a combination of training, motivation and subsequent application in the current clinical practice in an Italian teaching hospital
the supramolecular structure of liquid water and quantum coherent processes in biology
Vibrational spectroscopy provides a powerful tool to understand the molecular structures. When applied to the liquid water, this technique reveals so many details which can also shed a light on the supramolecular arrangement of the most ubiquitous of the substances. In particular, the two fluid model of water, proposed several decades ago, founds experimental evidence. Moreover, some fundamental parameters calculated in the realm of the theory of Quantum ElectroDynamics applied to liquid water can be actually measured showing an excellent agreement with the theory. This allows to add a dynamical origin to the mixed cluster model of water well known by the biologists for fifty years and opens the way to the dawn of a real quantum biology
Phase transitions of quasistationary states in the Hamiltonian Mean Field model
The out-of-equilibrium dynamics of the Hamiltonian Mean Field (HMF) model is
studied in presence of an externally imposed magnetic field h. Lynden-Bell's
theory of violent relaxation is revisited and shown to adequately capture the
system dynamics, as revealed by direct Vlasov based numerical simulations in
the limit of vanishing field. This includes the existence of an
out-of-equilibrium phase transition separating magnetized and non magnetized
phases. We also monitor the fluctuations in time of the magnetization, which
allows us to elaborate on the choice of the correct order parameter when
challenging the performance of Lynden-Bell's theory. The presence of the field
h removes the phase transition, as it happens at equilibrium. Moreover, regions
with negative susceptibility are numerically found to occur, in agreement with
the predictions of the theory.Comment: 6 pages, 7 figure
Controlling the Cassie-to-Wenzel Transition: an Easy Route towards the Realization of Tridimensional Arrays of Biological Objects
In this paper we provide evidence that the Cassie-to-Wenzel transition, despite its detrimental effects on the wetting properties of superhydrophobic surfaces, can be exploited as an effective micro-fabrication strategy to obtain highly ordered arrays of biological objects. To this purpose we fabricated a patterned surface wetted in the Cassie state, where we deposited a droplet containing genomic DNA. We observed that, when the droplet wets the surface in the Cassie state, an array of DNA filaments pinned on the top edges between pillars is formed. Conversely, when the Cassie-to-Wenzel transition occurs, DNA can be pinned at different height between pillars. These results open the way to the realization of tridimensional arrays of biological objects
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