Publications by authors named "Previtali C"

Purpose: The purpose of this study was to assess the performance of quantitative computed tomography (CT) imaging for detecting pancreatic fatty infiltration, using the results of histopathological analysis as reference.

Materials And Methods: Sixty patients who underwent pancreatic surgery for a pancreatic tumor between 2016 and 2019 were retrospectively included. There were 33 women and 27 men with a mean age of 56 ± 12 (SD) years (age range: 18-79 years).

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Background: Long-lasting shared research databases are an important source of epidemiological information and can promote comparison between different healthcare services. Here we present PROSAFE, an advanced international research network in intensive care medicine, with the focus on assessing and improving the quality of care. The project involved 343 ICUs in seven countries.

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This study aimed at examining and comparing the nutrient removal efficiency, biomass productivity and microbial community structure of two outdoor pilot-scale photobioreactors, namely a bubble column and a raceway pond, treating the liquid fraction of an agricultural digestate. Bacterial and eukaryotic communities were characterized using a metabarcoding approach and quantitative PCR. The abundance, composition, diversity, and dynamics of the main microbes were then correlated to the environmental conditions and operational parameters of the reactors.

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The bi-enzymatic synthesis of the antiviral drug vidarabine (arabinosyladenine, ara-A), catalyzed by uridine phosphorylase from (UP) and a purine nucleoside phosphorylase from (PNP), was re-designed under continuous-flow conditions. Glyoxyl-agarose and EziG1 (Opal) were used as immobilization carriers for carrying out this preparative biotransformation. Upon setting-up reaction parameters (substrate concentration and molar ratio, temperature, pressure, residence time), 1 g of vidarabine was obtained in 55% isolated yield and >99% purity by simply running the flow reactor for 1 week and then collecting (by filtration) the nucleoside precipitated out of the exiting flow.

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The use of conjugated polymer nanoparticles (CP NPs) of poly(9,9-dioctylfluorene-alt-benzothiadiazole) and poly(9,9-di-n-octylfluorenyl-2,7-diyl) as efficient photoinitiator systems (PIS) of vinyl polymerization in water is reported herein. CP NPs are biocompatible, excitable with blue commercial LEDs and, unlike visible light Type II PIS, do not need co-initiators to trigger a monomer chain reaction. CP NPs photoinitiate polymerization of a variety of acrylic monomers with initiation rates comparable to those observed for well-known Type II PIS.

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The development of convenient synthetic methods and improved materials for the production of high load-capacity and biocompatible drug delivery systems is a challenging task with important implications in health sciences. In this work, acrylamide/2-hydroxyethylmethacrylate and N-isopropylacrylamide/2-hydroxyethylmethacrylate hydrogels were synthesized by photopolymerization using energy-efficient green-LEDs. A functionalized silsesquioxane was used as both crosslinker and co-initiator for the photopolymerization.

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The photophysical and photochemical properties of the xanthene dyes mercurochrome (MCr) and eosin-Y (Eos); and the phenazine dye safranine-O (SF) are evaluated in the presence of amino-terminated polyamidoamine (PAMAM) dendrimers of low generations. The dendrimers produce a red shift in the UV-vis absorption spectra of the dyes, which increases with concentration and the size of the PAMAM molecule. The Stern-Volmer plots of fluorescence quenching for xanthenic dyes present a downward curvature.

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The interaction of the singlet and triplet excited states of the synthetic dye safranine-O with carboxyl-terminated poly(amidoamine) (PAMAM) dendrimers was investigated in a buffer solution at pH 8. Low half-generation PAMAM dendrimers (G -0.5; G +0.

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Article Synopsis
  • The study analyzes the interaction between xanthene dyes (Eosin Y, Erythrosin B, and Rose Bengal) and amino-terminated PAMAM dendrimers in alkaline solutions, noting significant changes in UV/Vis absorption and fluorescence.
  • High binding constants indicate strong interactions between the dyes and dendrimers, with bathochromic shifts in absorption spectra correlating to dendrimer size.
  • Laser flash photolysis reveals decreased triplet lifetimes and increased absorption of semireduced dyes, suggesting efficient electron transfer from PAMAM to the xanthene dyes.
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The prompt availability of reliable epidemiological information on emerging pandemics is crucial for public health policy-makers. Early in 2013, a possible new H1N1 epidemic notified by an intensive care unit (ICU) to GiViTI, the Italian ICU network, prompted the re-activation of the real-time monitoring system developed during the 2009-2010 pandemic. Based on data from 216 ICUs, we were able to detect and monitor an outbreak of severe H1N1 infection, and to compare the situation with previous years.

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The interaction of the triplet state of the synthetic dye phenosafranine (3,7-diamino-5-phenylphenazinium chloride) with indolic compounds of biological relevance was investigated in water by means of laser flash photolysis. The rate constants for the triplet quenching were determined. The quenching process may be explained by an electron transfer from the indole to the dye in its triplet state.

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The objectives of the present work were to verify whether simultaneous exposure to Hoechst 33342 and UV irradiation during sorting by flow cytometry may induce gene point mutations in bovine sperm and to assess whether the dye incorporated in the sperm may imply a mutagenic effect during the embryonic development. To this aim, high-resolution melt analysis (HRMA) was used to discriminate variations of single nucleotides in sexed vs. non-sexed control samples.

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We report herein a study on photoinduced electron transfer (eT) and energy transfer (ET) processes occurring between 9-methylanthracene-acrylate (A) and N,N-dimethylaniline-acrylate (D) derivatives incorporated into polymeric nanoparticles (NP). Five types of NPs were synthesized: PAD0, PAD25, PAD75, PD25, and PD75. All NPs are composed of a crosslinked polymer matrix of methyl methacrylate and ethylene glycol dimethacrylate.

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Electron transfer (ET) rate constants were determined by means of lifetime measurements for the fluorescence quenching and by laser flash photolysis for the triplet quenching of the dye eosin Y by benzoquinones in acetonitrile. The results represent a new aspect of the dependence of the rate constants with the driving force in the diffusion limit region. That is, the rate constants for singlet quenching in the highly negative region of ΔGet do not decrease as predicted by Marcus theory, but rather show a small positive dependence on the driving force.

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Methylene green is a versatile dye that can be used in a wide range of technical applications, most of which require the dye to be pure. Because commercial lots of methylene green are known to be heterogeneous, we report a thin layer chromatographic method for checking purity. We also describe a simple and effective flash chromatographic purification procedure for subsequent purification.

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Article Synopsis
  • The study focused on the behavior of Safranine-O in reverse micelles made with AOT, highlighting its triplet state dynamics.
  • The triplet state is formed regardless of pH and has a longer lifetime in reverse micelles than in organic solvents, indicating a protective environment from protons.
  • Quenching effects from different amines were examined, showing that while tributylamine's quenching is similar to alcohol, triethanolamine is significantly more effective in reverse micelles due to faster kinetic processes.
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We report herein the solvent and temperature effects on the emission of the intermolecular exciplexes 1-cyanonaphthalene/triethylamine and 1-methylnaphthalene/triethylamine and the intramolecular exciplexes formed by the bichromophoric compounds diethyl-(3-naphthalen-1-yl-propyl)-amine (I), diethyl-(2-naphthalen-1-yl-ethyl)-amine (II), 3-[ethyl-(2-naphthalen-1-yl-ethyl)-amino]-propionitrile (III) and 3-[(2-cyano-ethyl)-(2-naphthalen-1-yl-ethyl)-amino]-propionitrile (IV). The results are interpreted within the formalism of the semiclassical Marcus theory for radiative back electron transfer (BET) reactions. We show that, following a few simple assumptions, reliable values of the Gibbs free energy changes (DeltaG(epsilon)(-et)) and the solvent reorganization energies (lambda(epsilon)(s)) associated to the BET reactions (and their corresponding enthalpic and entropic contributions) can be estimated directly from the emission of the CT states.

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  • The study investigates how a series of N-methyl and N-H substituted indoles quench the fluorescence of pyrene in isooctane at room temperature.
  • The quenching mechanism is primarily through charge-transfer (CT), with N-H indoles causing unusual upward deviations in fluorescence plots due to self-quenching by free indoles.
  • Adding small amounts of pyridine or propanol significantly enhances the quenching efficiency, indicating that proton transfer plays a role in the self-quenching process.
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  • The study measured electron-transfer rate constants through fluorescence quenching of specific compounds, focusing on reactions involving aromatic amines and synthetic dyes as electron donors and acceptors.
  • The experiments were conducted in acetonitrile at room temperature (298 K), covering a range of Gibbs free energy changes (DeltaG(et)).
  • Contrary to predictions from Marcus theory, the results showed a slight increase in quenching rate constants as DeltaG(et) decreased, indicating that existing theories may need refinement to fully explain these observations.
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Tetraalkylammonium salts, characterized by an aromatic system pending from one of the alkyl chains, are taken as model systems to study the spectroscopic and redox properties of the aromatic centre under the field effects exerted by the charged group through alkyl bridges of varying length. The changes in the aromatic's redox properties, due to the net field effect and its different components, are interpreted on theoretical bases.

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Article Synopsis
  • The study examined how certain amines quench the excited states of a dye called phenosafranine in solvents like acetonitrile and methanol.
  • The singlet state quenching was influenced by the amines' one-electron redox potential, indicating a charge transfer mechanism, while the triplet state showed inconsistent behaviors, potentially involving reversible intermediate complexes in methanol.
  • Results suggested that triplet state quenching involves proton transfer, with the nature of the quenching process (reversible in methanol and irreversible in acetonitrile) supported by transient absorption spectroscopy that tracked changes in the dye's state.
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  • Characterization of excited states of palythine in water shows it has low photodegradation, indicating high stability under light exposure.
  • Laser flash photolysis experiments revealed a transient spectrum and a triplet state lifetime of about 9 microseconds, with triplet energy near 330 kJ/mol.
  • Comparisons with other mycosporine-like amino acids suggest that geometrical isomerization may play a role in their rapid deactivation.
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The quenching of anthracene fluorescence by indole (IN), 1,2-dimethylindole (DMI), tryptophan (Trp) and indole 3-acetic acid (IAA) in dimiristoylphophatidylcholine (DMPC) and palmitoyloleoylphosphatidylcholine (POPC) lipid bilayers was investigated. The studies were carried out at 25 degrees C in POPC vesicles and below (15 degrees C) and above (35 degrees C) the phase transition temperature (24 degrees C) of DMPC. A very efficient quenching of the anthracene fluorescence by IN and DMI in the lipid membrane is observed in all cases.

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The photochemistry of Ru(bpy)(3)+2 in the presence of amines was investigated in water by laser flash photolysis. N,N'-Dimethylaniline and p-phenylenediamine quench the luminescent metal to ligand charge transfer (MLCT) excited state of the complex by an electron transfer reaction that produces the semireduced form Ru(bpy)3+ in relatively high yields. On the other hand, triethylamine (TEA) and aniline do not quench the MLCT.

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