3,443 research outputs found
A Bayesian analysis of neutron spin echo data on polymer coated gold nanoparticles in aqueous solutions
We present a neutron spin echo study (NSE) of the nanosecond dynamics of
polyethylene glycol (PEG) functionalised nanosized gold particles dissolved in
DO at two temperatures and two different PEG molecular weights. The
analysis of the NSE data was performed by applying a Bayesian approach to the
description of time correlation function decays in terms of exponential terms,
recently proved to be theoretically rigorous. This approach, which addresses in
a direct way the fundamental issue of model choice in any dynamical analysis,
provides here a guide to the most statistically supported way to follow the
decay of the Intermediate Scattering Functions I(Q, t) by basing on statistical
grounds the choice of the number of terms required for the description of the
nanosecond dynamics of the studied systems. Then, the presented analysis avoids
from the start resorting to a pre-selected framework and can be considered as
model free. By comparing the results of PEG coated nanoparticles with those
obtained in PEG2000 solutions, we were able to disentangle the translational
diffusion of the nanoparticles from the internal dynamics of the polymer
grafted to them, and to show that the polymer corona relaxation follows a pure
exponential decay in agreement with the behavior predicted by coarse grained
molecular dynamics simulations and theoretical models. This methodology has one
further advantage: in the presence of a complex dynamical scenario I(Q,t) is
often described in terms of the Kohlrausch-Williams-Watts function that can
implicitly represent a distribution of relaxation times. By choosing to
describe the I(Q,t) as a sum of exponential functions and with the support of
the Bayesian approach, we can explicitly determine when a finer-structure
analysis of the dynamical complexity of the system exists according to the
available data without the risk of overparametrisation
Environment-Induced Reversible Modulation of Optical and Electronic Properties of Lead Halide Perovskites and Possible Applications to Sensor Development: A Review
none4siLead halide perovskites are currently widely investigated as active materials in photonic and optoelectronic devices. While the lack of long term stability actually limits their application to commercial devices, several experiments demonstrated that beyond the irreversible variation of the material properties due to degradation, several possibilities exist to reversibly modulate the perovskite characteristics by acting on the environmental conditions. These results clear the way to possible applications of lead halide perovskites to resistive and optical sensors. In this review we will describe the current state of the art of the comprehension of the environmental effects on the optical and electronic properties of lead halide perovskites, and of the exploitation of these results for the development of perovskite-based sensors.openDe Giorgi, ML; Milanese, S; Klini, A; Anni, MDe Giorgi, Ml; Milanese, S; Klini, A; Anni,
Heat-shock pretreatment inhibits sorbitol-induced apoptosis in K562, U937 and HeLa cells.
The aim of this study was to determine whether heat-shock pretreatment
exerted a protective effect against sorbitol-induced apoptotic
cell death in K562, U937 and HeLa cell lines and whether
such protection was associated with a decreased cytochrome c
release from mithocondria and a decreased activation of caspase-9
and -3. Following heat-shock pretreatment (42 6 0.3C for 1 hr),
these cell lines were exposed to sorbitol for 1 hr. Apoptosis was evaluated
by DNA fragmentation, whereas caspase-9,-3 activation, cytochrome
c release and heat-shock protein70 (HSP70) were assayed
by Western Blot. Sorbitol exposure-induced apoptosis in these different
cell lines with a marked activation of caspase-9 and caspase-
3, whereas heat-shock pretreatment before sorbitol exposure,
induced expression of HSP70 and inhibited sorbitol-mediated cytochrome
c release and subsequent activation of caspase-9 and caspase-
3. Similarly, overexpression of HSP70 in the three cell lines
studied prevented caspase-9 cleavage and activation as well as cell
death. Furthermore, we showed that the mRNA expression of iNOS
decreased during both the heat-shock treatment and heat-shock
pretreatment before sorbitol exposure. By contrast, the expression
of Cu-Zn superoxide dismutase (SOD) and Mn-SOD proteins
increased during heat-shock pretreatment before sorbitol exposure.
We conclude that, heat-shock pretreatment protects different cell
lines against sorbitol-induced apoptosis through a mechanism that
is likely to involve SOD family members
GITMO REGISTRY STUDY ON ALLOGENEIC TRANSPLANTATION IN PATIENTS AGED OVER 60 FROM 2000 TO 2017. IMPROVEMENTS AND CRITICISMS
Spleen histology in children with sickle cell disease and hereditary spherocytosis: Hints on the disease pathophysiology
open2Hereditary spherocytosis (HS) and sickle cell disease (SCD) are associated with splenomegaly and spleen dysfunction in pediatric patients. Scant data exist on possible correlations between spleen morphology and function in HS and SCD. This study aimed to assess the histological and morphometric features of HS and SCD spleens, in order to get possible correlations with disease pathophysiology. In a large series of spleens from SCD, HS and control patients the following parameters were considered: (i) macroscopic features; (ii) lymphoid follicle (LF) density; (iii) presence of peri-follicular marginal zones (MZs); (iv) presence of Gamna-Gandy bodies; (v) density of CD8-positive sinusoids; (vi) density of CD34-positive microvessels; (vii) presence/distribution of fibrosis and SMA-positive myoid cells; (viii) density of CD68-positive macrophages. SCD and HS spleens have similar macroscopic features. SCD spleens had lower LF density and fewer MZs than HS spleens and controls. SCD also showed lower CD8-positive sinusoid density, increased CD34-positive microvessel density and SMA-positive myoid cells, and higher prevalence of fibrosis and Gamna-Gandy bodies. HS had lower LF and CD8-positive sinusoid density than controls. No significant differences were noted in red pulp macrophages. By multivariate analysis, the majority of HS spleens clustered with controls, while SCD grouped separately. A multi-parametric score could predict the degree of spleen changes irrespective of the underlying disease. In conclusion, SCD spleens display greater histologic effacement than HS and SCD-related changes suggest impaired function due to vascular damage. These observations may contribute to guide the clinical management of patients.embargoed_20161128Alaggio, RitaAlaggio, Rita; Gamba, Piergiorgi
Resting state functional thalamic connectivity abnormalities in patients with post-stroke sleep apnoea: a pilot case-control study
OBJECTIVE: Sleep apnoea is common
after stroke, and has adverse effects on the
clinical outcome of affected cases. Its pathophysiological
mechanisms are only partially known. Increases
in brain connectivity after stroke might influence
networks involved in arousal modulation
and breathing control. The aim of this study was to
investigate the resting state functional MRI thalamic
hyper connectivity of stroke patients affected
by sleep apnoea (SA) with respect to cases not
affected, and to healthy controls (HC).
PATIENTS AND METHODS: A series of stabilized
strokes were submitted to 3T resting state
functional MRI imaging and full polysomnography.
The ventral-posterior-lateral thalamic nucleus was
used as seed.
RESULTS: At the between groups comparison
analysis, in SA cases versus HC, the regions significantly
hyper-connected with the seed were
those encoding noxious threats (frontal eye
field, somatosensory association, secondary visual
cortices). Comparisons between SA cases
versus those without SA, revealed in the former
group significantly increased connectivity with
regions modulating the response to stimuli independently
to their potentiality of threat (prefrontal,
primary and somatosensory association, superolateral
and medial-inferior temporal, associative
and secondary occipital ones). Further
significantly functionally hyper connections were
documented with regions involved also in the modulation
of breathing during sleep (pons, midbrain,
cerebellum, posterior cingulate cortices), and in
the modulation of breathing response to chemical
variations (anterior, posterior and para-hippocampal
cingulate cortices).
CONCLUSIONS: Our preliminary data support
the presence of functional hyper connectivity in
thalamic circuits modulating sensorial stimuli, in
patients with post-stroke sleep apnoea, possibly
influencing both their arousal ability and breathing
modulation during sleep
Investigation of the Role of the Environment on the Photoluminescence and the Exciton Relaxation of CsPbBr3 Nanocrystals Thin Films
In this work, we present a detailed optical investigation of the effects of the environment
on the photoluminescence (PL) spectra and the relaxation dynamics of pristine and aged CsPbBr
3
nanocrystal (NC) thin films. We demonstrate that, contrary to previous results on similar NCs,
the PL intensity of pristine NCs is higher when the sample is in wet air than in vacuum, due to
the passivation of defects reducing the free exciton trapping and the bound excitons non-radiative
relaxation. The aged NCs show a PL intensity increase in wet air nine times stronger than the
pristine ones, due to an interplay between static and dynamic effects, increasing the number of
emitting NCs and reducing the non-radiative recombination rate of free excitons. These results
improve the understanding of the possible interactions between perovskite NCs and the environment,
which could be relevant for the development of optical gas sensors exploiting perovskite NCs
Highly efficient smart photovoltachromic devices with tailored electrolyte composition
Driven by the tremendous opportunities offered by dye solar cells technology in terms of building integration, a new generation of smart multifunctional photoelectrochemical cells has the potential to attract the interest of a rapidly growing number of research institutions and industrial companies. Photovoltachromic devices are capable to produce a smart modulation of the optical transmittance and, at the same time, to generate electrical power by means of solar energy conversion. In this work, a specifically designed bifunctional counterelectrode has been realized by depositing a C-shaped platinum frame which bounds a square region occupied by a tungsten oxide (WO3) film onto a transparent conductive substrate. These two regions have been electrically separated to make possible distinct operations on one or both of the available circuits. Such an unconventional counterelectrode makes it possible to achieve a twofold outcome: a smart and fast-responsive control of the optical transmittance and a relatively high photovoltaic conversion efficiency. In particular we investigated the effect of the electrolyte composition on both photoelectrochromic and photovoltaic performances of such devices by systematically tuning the iodide content in the electrolyte. The best result was obtained by filling the cell with an iodine concentration of 0.005 M: a coloration efficiency of 61.10 cm(2) C-1 at a wavelength of 780 nm and, at the same time, a photovoltaic conversion efficiency of 6.55% have been reported
Involvement of FOXO Transcription Factors, TRAIL-FasL/Fas, and Sirtuin Proteins Family in Canine Coronavirus Type II-Induced Apoptosis
n our previous study, we have shown that canine coronavirus type II (CCoV-II) activates both extrinsic and intrinsic apoptotic pathway in a canine fibrosarcoma cell line (A-72 cells). Herein we investigated the role of Sirtuin and Forkhead box O (FOXO) families in this experimental model using Nortern Blot and Western Blot analysis. Our results demonstrated that mitochondrial SIRT3 and SIRT4 protein expression increased from 12 and 24 h post infection (p.i.) onwards, respectively, whereas the nuclear SIRT1 expression increased during the first 12 h p.i. followed by a decrease after 36 h p.i., reaching the same level of control at 48 h p.i. Sirtuins interact with/and regulate the activity of FOXO family proteins, and we herein observed that FOXO3A and FOXO1 expression increased significantly and stably from 12 h p.i. onwards. In addition, CCoV-II induces a remarkable increase in the expression of TNF-related apoptosis-inducing ligand (TRAIL), while we observed a slight up-regulation of FasL/Fas at 36 p.i. with a decrease of both proteins at the end of infection. Furthermore, we found that virus infection increased both bax translocation into mitochondria and decreased bcl-2 expression in cytosol in a time-dependent manner
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