7 research outputs found
Earthquake forecasting in Italy, before and after Umbria-Marche seismic sequence 1997. A review of the earthquake occurrence modeling at different spatio-temporal-magnitude scales.
The main goal of this work is to review the scientific researches carried out before and after the Umbria-Marche sequence related to the earthquake forecasting/prediction in Italy. In particular, I focus the attention on models that aim addressing three main practical questions: was (is) Umbria-Marche a region with high probability of occurrence of a destructive earthquake? Was a precursory activity recorded before the mainshock(s)? What was our capability to model the spatio-temporal-magnitude evolution of that seismic sequence? The models are reviewed pointing out what we have learned after the Umbria-Marche earthquakes, in terms of physical understanding of earthquake occurrence process, and of improving our capability to forecast earthquakes and to track in real-time seismic sequences
Electrochemistry of Room Temperature Protic Ionic Liquids: A Critical Assessment for Use as Electrolytes in Electrochemical Applications
Ten room temperature protic ionic liquids (RTPILs) have
been prepared
from low-molecular-weight Brønsted acids and amines with high
purity and minimal water content, and their electrochemical characteristics
determined using cyclic, microelectrode, and rotating disk electrode
voltammetries. Potential windows of the 10 RTPILs were established
at glassy carbon, gold, and platinum electrodes, where the largest
potential window is generally observed with glassy carbon electrodes.
The two IUPAC recommended internal potential reference systems, ferrocene/ferrocenium
and cobaltocenium/cobaltocene, were determined for the 10 RTPILs,
and their merits as well as limitations are discussed. Other electrochemical
properties such as mass transport and double layer capacitances were
also investigated. The potential applications of these RTPILs as electrolytes
for electrochemical energy devices were discussed, and two novel applications
using PILs for metal deposition and water electrolysis were demonstrated
Atomic Force Microscopy Reveals the Mechanobiology of Lytic Peptide Action on Bacteria
Increasing
rates of antimicrobial-resistant medically important
bacteria require the development of new, effective therapeutics, of
which antimicrobial peptides
(AMPs) are among the promising candidates. Many AMPs are membrane-active,
but their mode of action in killing bacteria or in inhibiting their
growth remains elusive. This study used atomic force microscopy (AFM)
to probe the mechanobiology of a model AMP (a derivative of melittin)
on living <i>Klebsiella pneumoniae</i> bacterial cells.
We performed <i>in situ</i> biophysical measurements to
understand how the melittin peptide modulates various biophysical
behaviors of individual bacteria, including the turgor pressure, cell
wall elasticity, and bacterial capsule thickness and organization.
Exposure of <i>K. pneumoniae</i> to the peptide had a significant
effect on the turgor pressure and Youngâs modulus of the cell
wall. The turgor pressure increased upon peptide addition followed
by a later decrease, suggesting that cell lysis occurred and pressure
was lost through destruction of the cell envelope. The Youngâs
modulus also increased, indicating that interaction with the peptide
increased the rigidity of the cell wall. The bacterial capsule did
not prevent cell lysis by the peptide, and surprisingly, the capsule
appeared unaffected by exposure to the peptide, as capsule thickness
and inferred organization were within the control limits, determined
by mechanical measurements. These data show that AFM measurements
may provide valuable insights into the physical events that precede
bacterial lysis by AMPs
Selenium Nanoparticles as Potential Drug-Delivery Systems for the Treatment of Parkinsonâs Disease
The development of efficient drug formulations for Parkinsonâs
disease (PD) treatment is challenged by achieving pharmacokinetic
profiles, reduced side effects, and better permeability through the
bloodâbrain barrier (BBB). As nanoparticles may facilitate
the delivery of drugs in the brain due to their high-loading capacity
and ability to cross biological barriers, we designed two different
types of selenium nanoparticles (SeNPs) that may increase the transport
of drugs across the BBB and may act as antioxidants at the site of
action. The SeNPs were functionalized with polyvinylpyrrolidone (PVP)
and polysorbate 20 (Tween) and characterized in terms of their size,
size distribution, shape, surface charge, and colloidal stability
in relevant biological media. Their drug-loading capacity was tested
using dopamine and l-DOPA as therapeutically active agents
for PD. Thermodynamic analysis revealed that binding processes occurred
spontaneously through hydrogen bond/van der Waals interactions or
electrostatic interactions. The strongest interaction was observed
between PVP-SeNPs and l-DOPA or dopamine, which was characterized
by a binding constant several orders of magnitude higher than for
Tween-SeNPs. However, the addition of human transferrin as a model
plasma protein significantly reduced this difference, which indicates
the crucial role of protein corona formation in the design of drug
nanodelivery systems. In vitro evaluation by cell-free
and cellular transwell models showed efficient internalization of
SeNP-loaded l-DOPA/dopamine by human endothelial brain cells,
while facilitated BBB permeability for l-DOPA, and dopamine
was achieved using PVP-SeNPs. Overall, the high potential of SeNPs
as drug-delivery vehicles in PD treatment was demonstrated
Copolyampholytes Produced from RAFT Polymerization of Protic Ionic Liquids
Polyampholytic
copolymers have been synthesized via reversible additionâfragmentation
chain transfer (RAFT) polymerization of protic ionic liquid monomers.
The monomers were prepared by acidâbase proton exchange between
acid and basic precursor conjugates, each containing one or more vinyl
pendant groups. The polymerization, which was carried out without
additional solvents present, led to high molecular weight glassy polymers,
which were stable in the form of bulk viscous liquid ionic complexes.
Various polyampholytes belonging to both linear and cross-linked families
were prepared by judiciously varying the molecular structure of the
acid precursor. Furthermore, by using solid-state NMR, the molecular
arrangement of the polymeric backbone was identified, highlighting
the presence of copolymers with both random and alternating copolymer
chains which in the latter case involves a regularly alternating acid
monomer, whereas the base occurs as a random sequence with the average
and most probable number of monomers dictated by the stoichiometry
used. The structural and mechanical properties of the resulting copolyampholytes
were characterized by atomic force microscopy, peak-force quantitative
nanomechanical analysis, differential scanning calorimetry, and small-angle
X-ray scattering. These showed that the final polymers were essentially
glassy and amorphous, with weak compositional fluctuations of the
order of a few monomers and Young moduli in the range 1â3 GPa
Selenium Nanoparticles as Potential Drug-Delivery Systems for the Treatment of Parkinsonâs Disease
The development of efficient drug formulations for Parkinsonâs
disease (PD) treatment is challenged by achieving pharmacokinetic
profiles, reduced side effects, and better permeability through the
bloodâbrain barrier (BBB). As nanoparticles may facilitate
the delivery of drugs in the brain due to their high-loading capacity
and ability to cross biological barriers, we designed two different
types of selenium nanoparticles (SeNPs) that may increase the transport
of drugs across the BBB and may act as antioxidants at the site of
action. The SeNPs were functionalized with polyvinylpyrrolidone (PVP)
and polysorbate 20 (Tween) and characterized in terms of their size,
size distribution, shape, surface charge, and colloidal stability
in relevant biological media. Their drug-loading capacity was tested
using dopamine and l-DOPA as therapeutically active agents
for PD. Thermodynamic analysis revealed that binding processes occurred
spontaneously through hydrogen bond/van der Waals interactions or
electrostatic interactions. The strongest interaction was observed
between PVP-SeNPs and l-DOPA or dopamine, which was characterized
by a binding constant several orders of magnitude higher than for
Tween-SeNPs. However, the addition of human transferrin as a model
plasma protein significantly reduced this difference, which indicates
the crucial role of protein corona formation in the design of drug
nanodelivery systems. In vitro evaluation by cell-free
and cellular transwell models showed efficient internalization of
SeNP-loaded l-DOPA/dopamine by human endothelial brain cells,
while facilitated BBB permeability for l-DOPA, and dopamine
was achieved using PVP-SeNPs. Overall, the high potential of SeNPs
as drug-delivery vehicles in PD treatment was demonstrated
Selenium Nanoparticles as Potential Drug-Delivery Systems for the Treatment of Parkinsonâs Disease
The development of efficient drug formulations for Parkinsonâs
disease (PD) treatment is challenged by achieving pharmacokinetic
profiles, reduced side effects, and better permeability through the
bloodâbrain barrier (BBB). As nanoparticles may facilitate
the delivery of drugs in the brain due to their high-loading capacity
and ability to cross biological barriers, we designed two different
types of selenium nanoparticles (SeNPs) that may increase the transport
of drugs across the BBB and may act as antioxidants at the site of
action. The SeNPs were functionalized with polyvinylpyrrolidone (PVP)
and polysorbate 20 (Tween) and characterized in terms of their size,
size distribution, shape, surface charge, and colloidal stability
in relevant biological media. Their drug-loading capacity was tested
using dopamine and l-DOPA as therapeutically active agents
for PD. Thermodynamic analysis revealed that binding processes occurred
spontaneously through hydrogen bond/van der Waals interactions or
electrostatic interactions. The strongest interaction was observed
between PVP-SeNPs and l-DOPA or dopamine, which was characterized
by a binding constant several orders of magnitude higher than for
Tween-SeNPs. However, the addition of human transferrin as a model
plasma protein significantly reduced this difference, which indicates
the crucial role of protein corona formation in the design of drug
nanodelivery systems. In vitro evaluation by cell-free
and cellular transwell models showed efficient internalization of
SeNP-loaded l-DOPA/dopamine by human endothelial brain cells,
while facilitated BBB permeability for l-DOPA, and dopamine
was achieved using PVP-SeNPs. Overall, the high potential of SeNPs
as drug-delivery vehicles in PD treatment was demonstrated