Development and characterization of conductive and biocompatible scaffolds for biomedical applications

Nowadays, there is a growing demand of tissue engineered scaffolds for cell culture and subsequent tissue regeneration. In this line, biopolymers and biodegradable synthetic polymers have been proposed for fabrication of tissue engineered mats, which must mimic the intrinsic features of the natural extracellular matrix in terms of, among others, morphology, functionality, biocompatibility or degradability. Electrospinning is a popular technique to produce scaffolds that has the potential to address these issues. In this work, a tailoring methodology was applied to obtain highly functionalized conductive polyester based scaffolds with high biocompatibility. For this purpose, blends based on polycaprolactone (PCL), gelatin (Ge) and polyaniline (PAni) were prepared into a hydrolytic solvent system and electrospun after several dissolution times. Regarding the biocompatibilization and the functionalization strategies, analyzing the scaffolds obtained after 24 h of dissolution time, it was found that the general characteristics, like the fiber diameter, thermo-oxidative stability and the thermal properties were influenced by the Ge concentration, while the PAni brought the electric conductivity to the nanofibers. The dissolution time influenced the resultant physico-chemical properties and morphology of the electrospun scaffolds. Bead-free fibers were obtained after 24, 48 and 72 h of dissolution time, while some beads appeared after 96 h. The DT influenced also the molar mass and the lamellar thickness of the electrospun scaffolds decreasing them, while increasing the crystallinity degree. The preliminary in vitro validation revealed the release of the Ge fraction into the PBS solution and the consequent decrease of the initial mass of the nanofibrous scaffolds. In this line, future investigations for a deeper validation of the scaffolds may bring valuable information about their suitability in terms of in vitro biocompatibility and further in vivo implantation

Yield stress fluids and fundamental particle statistics

Yield stress in complex fluids is described by resorting to fundamental statistical mechanics for clusters with different particle occupancy numbers. Probability distribution functions are determined for canonical ensembles of volumes displaced at the incipient motion in three representative states (single, double, and multiple occupancies). The statistical average points out an effective solid fraction by which the yield stress behavior is satisfactorily described in a number of aqueous (Si3N4, Ca3(PO4)2, ZrO2, and TiO2) and non-aqueous (Al2O3/decalin and MWCNT/PC) disperse systems. Interestingly, the only two model coefficients (maximum packing fraction and stiffness parameter) turn out to be correlated with the relevant suspension quantities. The latter relates linearly with (Young’s and bulk) mechanical moduli, whereas the former, once represented versus the Hamaker constant of two particles in a medium, returns a good linear extrapolation of the packing fraction for the simple cubic cell, here recovered within a relative error ≈ 1.3%

Tof ion spectra de convolution for lasergenerated plasmas

EnA study of different targets (Fe, Ti, Ni, Al2O3) ablation, in vacuum, by using a ns Nd:YAG laser radiation, 1064 nm and 532 nm (second harmonic) wavelengths, is reported. Laser pulse with high intensity generates a plasma at the target surface, with high non-isotropic emission of neutral and ion species, mainly emitted along the normal to the target surface. Time of flight (TOF) measurements are performed by using an ion collector consisting of a collimated Faraday cup placed along the normal to the target surface and an Ion Energy Analyzer (IEA) detector. The TOF spectra are converted as a function of the ions velocity and they are deconvolved for the various ion charge states by using the “Coulomb-Boltzmann shifted” function approach through the “Peakfit” mathematical code. The fit of the experimental distribution data permits to estimate the equivalent plasma temperature and the average energy shift of the distributions as a function of the ion charge state. This energy shift leads to the evaluation of the electric field producing the ion acceleration inside the plasma

Lizards as model organisms of sex chromosome evolution: What we really know from a systematic distribution of available data?

Lizards represent unique model organisms in the study of sex determination and sex chromosome evolution. Among tetrapods, they are characterized by an unparalleled diversity of sex determination systems, including temperature-dependent sex determination (TSD) and genetic sex determination (GSD) under either male or female heterogamety. Sex chromosome systems are also extremely variable in lizards. They include simple (XY and ZW) and multiple (X1X2Y and Z1Z2W) sex chromosome systems and encompass all the different hypothesized stages of diversification of heterogametic chromosomes, from homomorphic to heteromorphic and completely heterochromatic sex chromosomes. The co-occurrence of TSD, GSD and different sex chromosome systems also characterizes different lizard taxa, which represent ideal models to study the emergence and the evolutionary drivers of sex reversal and sex chromosome turnover. In this review, we present a synthesis of general genome and karyotype features of non-snakes squamates and discuss the main theories and evidences on the evolution and diversification of their different sex determination and sex chromosome systems. We here provide a systematic assessment of the available data on lizard sex chromosome systems and an overview of the main cytogenetic and molecular methods used for their identification, using a qualitative and quantitative approach

L’efficacia degli interventi di sviluppo: la sfida della qualità per la cooperazione italiana

La ricerca ha analizzato in maniera critica le valutazioni indipendenti commissionate dall’Ufficio IX-Valutazione e visibilità delle iniziative della Direzione Generale Cooperazione allo Sviluppo (DGCS) del Ministero degli Affari Esteri e della Cooperazione Internazionale (MAECI) nel periodo 2009-2016, al fine di ricostruire i punti di forza e di debolezza della Cooperazione Italiana, partendo da risultati, criticità, buone pratiche e lezioni apprese registrate sul campo dalle iniziative da essa finanziate. Obiettivo della ricerca è fornire elementi interpretativi circa il grado di efficacia delle iniziative di sviluppo della Cooperazione Italiana. Alla luce dei risultati emersi, lo studio propone una riflessione, volta a contribuire al dibattito sul miglioramento del sistema italiano di cooperazione, che considera: i) gli obiettivi stabiliti a livello internazionale dall’Agenda 2030 per lo Sviluppo Sostenibile; ii) gli impegni a garanzia della qualità della cooperazione promossi dalla Global Partnership for Effective Development Cooperation (GPED) cui l’Italia partecipa; iii) le opportunità di miglioramento offerte dalla Legge 11 agosto 2014, n. 125, Disciplina generale sulla cooperazione internazionale per lo sviluppo, che ha novellato la previgente normativa che per 27 anni ha regolato il settore della cooperazione allo sviluppo; iv) le raccomandazioni espresse negli anni dall’OECD-DAC per mezzo delle sue peer review. La ricerca si articola in 5 Capitoli. Il primo Capitolo contestualizza le nuove sfide per uno sviluppo sostenibile efficace lanciate dall’Agenda 2030, dai suoi Sustainable Development Goals (SDGs) e dalla GPED, alla luce di una rilettura del percorso che ha condotto alla loro adozione e che ragiona sul concetto di sviluppo in chiave storica. Il secondo Capitolo descrive sinteticamente le novità con le quali la Cooperazione Italiana dovrà confrontarsi a seguito della riforma operata dalla L. 125/2014 e propone un breve excursus sulle politiche di efficacia e valutazione attuate dal sistema, al fine di introdurre le riflessioni sviluppate nel proseguo dello studio. Il terzo Capitolo, dopo una presentazione tecnica delle 26 valutazioni commissionate dall’Ufficio IX-Valutazione e visibilità delle iniziative della DGCS nel periodo 2009-2016, si focalizza sull’analisi delle 23 valutazioni indipendenti in ambito di cooperazione e ricostruisce i punti di forza e di debolezza della Cooperazione Italiana. La riflessione prosegue esaminando quali sono le opportunità di miglioramento dell’efficacia del sistema grazie alle novità introdotte dalla riforma della cooperazione allo sviluppo del 2014. Il quarto Capitolo si concentra sull’assistenza umanitaria, un importante settore d’azione della Cooperazione Italiana, per il quale sono state effettuate 3 valutazioni specifiche nel periodo 2009-2016. L’assistenza umanitaria italiana rappresenta un caso di buona pratica nella retroazione delle raccomandazioni ricevute in sede di valutazione, pertanto si è scelto di illustrate in dettaglio questo settore e le novità che l’adozione della L. 125/2014 ha apportato, individuando le sfide che la risposta umanitaria italiana dovrà affrontare nel breve futuro. Infine, il quinto Capitolo trae spunto dalla valutazione del più consistente credito di aiuto mai erogato dalla Cooperazione Italiana (Gilgel Gibe II) per approfondire una questione di assoluto rilievo atta a garantire una maggiore qualità dell’azione di cooperazione internazionale dell’Italia, ossia il legame tra accountability, policy making e valutazione

First Insights on the Karyotype Diversification of the Endemic Malagasy Leaf-Toed Geckos (Squamata: Gekkonidae: Uroplatus)

We provide here the first karyotype description of eight Uroplatus species and a characterization of their chromosomal diversity. We performed a molecular taxonomic assessment of several Uroplatus samples using the mitochondrial 12S marker and a comparative cytogenetic analysis with standard karyotyping, silver staining (Ag-NOR) and sequential C-banding + Giemsa, +Chromomycin A3 (CMA3), +4',6-diamidino-2-phenylindole (DAPI). We found chromosomal variability in terms of chromosome number (2n = 34-38), heterochromatin composition and number and localization of loci or Nucleolar Organizer Regions (NORs) (alternatively on the 2nd, 6th, 10th or 16th pair). Chromosome morphology is almost constant, with karyotypes composed of acrocentric chromosomes, gradually decreasing in length. C-banding evidenced a general low content of heterochromatin, mostly localized on pericentromeric and telomeric regions. Centromeric bands varied among the species studied, resulting in CMA3 positive and DAPI negative or positive to both fluorochromes. We also provide evidence of a first putative heteromorphic sex chromosome system in the genus. In fact, in U. alluaudi the 10th pair was highly heteromorphic, with a metacentric, largely heterochromatic W chromosome, which was much bigger than the Z. We propose an evolutionary scenario of chromosome reduction from 2n = 38 to 2n = 34, by means of translocations of microchromosomes on larger chromosomes (often involving the NOR-bearing microchromosomes). Adding our data to those available from the literature, we show that similar processes characterized the evolutionary radiation of a larger gecko clade. Finally, we hypothesize that sex chromosome diversification occurred independently in different genera