11 research outputs found
Nanoparticle-doped electrospun fiber random lasers with spatially extended light modes
Complex assemblies of light-emitting polymer nanofibers with molecular
materials exhibiting optical gain can lead to important advance to amorphous
photonics and to random laser science and devices. In disordered mats of
nanofibers, multiple scattering and waveguiding might interplay to determine
localization or spreading of optical modes as well as correlation effects. Here
we study electrospun fibers embedding a lasing fluorene-carbazole-fluorene
molecule and doped with titania nanoparticles, which exhibit random lasing with
sub-nm spectral width and threshold of about 9 mJ cm^-2 for the absorbed
excitation fluence. We focus on the spatial and spectral behavior of optical
modes in the disordered and non-woven networks, finding evidence for the
presence of modes with very large spatial extent, up to the 100
micrometer-scale. These findings suggest emission coupling into integrated
nanofiber transmission channels as effective mechanism for enhancing spectral
selectivity in random lasers and correlations of light modes in the complex and
disordered material.Comment: 22 pages, 6 figure
Diverse regimes of mode intensity correlation in nanofiber random lasers through nanoparticle doping
Random lasers are based on disordered materials with optical gain. These
devices can exhibit either intensity or resonant feedback, relying on diffusive
or interference behaviour of light, respectively, which leads to either
coupling or independent operation of lasing modes. We study for the first time
these regimes in complex, solid-state nanostructured materials. The number of
lasing modes and their intensity correlation features are found to be
tailorable in random lasers made of light-emitting, electrospun polymer fibers
upon nanoparticle doping. By material engineering, directional waveguiding
along the length of fibers is found to be relevant to enhance mode correlation
in both intensity feedback and resonant feedback random lasing. The here
reported findings can be used to establish new design rules for tuning the
emission of nano-lasers and correlation properties by means of the
compositional and morphological properties of complex nanostructured materials.Comment: 30 pages, 10 figure
Sub-ms dynamics of the instability onset of electrospinning
Electrospun polymer jets are imaged for the first time at an ultra-high rate
of 10,000 frames per second, investigating the process dynamics, and the
instability propagation velocity and displacement in space. The polymer
concentration, applied voltage bias and needle-collector distance are
systematically varied, and their influence on the instability propagation
velocity and on the jet angular fluctuations analyzed. This allows us to unveil
the instability formation and cycling behavior, and its exponential growth at
the onset, exhibiting radial growth rates of the order of 10^3 s^-1. Allowing
the conformation and evolution of polymeric solutions to be studied in depth,
high-speed imaging at sub-ms scale shows a significant potential for improving
the fundamental knowledge of electrified jets, leading to obtain finely
controllable bending and solution stretching in electrospinning, and
consequently better designed nanofibers morphologies and structures.Comment: 23 pages, 9 figure
Electrostatic mechanophores in tuneable light-emitting piezo-polymer nanowires
Electromechanical coupling through piezoelectric polymer chains allows the
emission of organic molecules in active nanowires to be tuned. This effect is
evidenced by highly bendable arrays of counter-ion dye-doped nanowires made of
a poly(vinylidenefluoride) copolymer. A reversible redshift of the dye emission
is found upon the application of dynamic stress during highly accurate bending
experiments. By density functional theory calculations it is found that these
photophysical properties are associated with mechanical stresses applied to
electrostatically interacting molecular systems, namely to counterion-mediated
states that involve light-emitting molecules as well as charged regions of
piezoelectric polymer chains. These systems are an electrostatic class of
supramolecular functional stress-sensitive units, which might impart new
functionalities in hybrid molecular nanosystems and anisotropic nanostructures
for sensing devices and soft robotics.Comment: 32 pages, 18 figure
Atlante storico del diritto dei dati. Anni 2020-2022
Raccolta anni 2020-2022 della rubrica Diritto e nuove tecnologie pubblicata sulla rivista Persona e Mercat
Safety and efficacy of COVID-19 vaccines in patients on dialysis: a multicentre cohort study in Italy
Background The aim of this study was to evaluate the efficacy and safety of COVID-19 vaccines in patients undergoing haemodialysis in Italy compared to the general population.Methods In this cohort study, 118 dialysis centres from 18 Italian Regions participated. Individuals older than 16 years on dialysis treatment for at least 3 months, who provided informed consent were included. We collected demographic and clinical information, as well as data on vaccination status, hospitalisations, access to intensive care units and adverse events. We calculated the incidence, hospitalisation, mortality, and fatality rates in the vaccinated dialysis cohort, adjusted for several covariates. The incidence rates of infection in the dialysis cohort and the general population were compared through Standardised Incidence Rate Ratio.Results The study included 6555 patients vaccinated against SARS-CoV-2 infection according to the schedule recommended in Italy. Between March 2021 and May 2022, there were 1096 cases of SARS-CoV-2 infection, with an incidence rate after completion of the three-dose vaccination cycle of 37.7 cases per 100 person-years. Compared to the general population, we observed a 14% reduction in the risk of infection for patients who received three vaccine doses (Standardised Incidence Rate Ratio: 0.86; 95% Confidence Interval: 0.81-0.91), whereas no statistically significant differences were found for COVID-19-related hospitalisations, intensive care unit admissions or death. No safety signals emerged from the reported adverse events.Conclusions The vaccination program against SARS-CoV-2 in the haemodialysis population showed an effectiveness and safety profile comparable to that seen in the general population
Safety and efficacy of COVID-19 vaccines in patients on dialysis: a multicentre cohort study in Italy
Background: The aim of this study was to evaluate the efficacy and safety of COVID-19 vaccines in patients undergoing haemodialysis in Italy compared to the general population. Methods: In this cohort study, 118 dialysis centres from 18 Italian Regions participated. Individuals older than 16 years on dialysis treatment for at least 3 months, who provided informed consent were included. We collected demographic and clinical information, as well as data on vaccination status, hospitalisations, access to intensive care units and adverse events. We calculated the incidence, hospitalisation, mortality, and fatality rates in the vaccinated dialysis cohort, adjusted for several covariates. The incidence rates of infection in the dialysis cohort and the general population were compared through Standardised Incidence Rate Ratio. Results: The study included 6555 patients vaccinated against SARS-CoV-2 infection according to the schedule recommended in Italy. Between March 2021 and May 2022, there were 1096 cases of SARS-CoV-2 infection, with an incidence rate after completion of the three-dose vaccination cycle of 37.7 cases per 100 person-years. Compared to the general population, we observed a 14% reduction in the risk of infection for patients who received three vaccine doses (Standardised Incidence Rate Ratio: 0.86; 95% Confidence Interval: 0.81–0.91), whereas no statistically significant differences were found for COVID-19-related hospitalisations, intensive care unit admissions or death. No safety signals emerged from the reported adverse events. Conclusions: The vaccination program against SARS-CoV-2 in the haemodialysis population showed an effectiveness and safety profile comparable to that seen in the general population. Graphical abstract: [Figure not available: see fulltext.