Double In Situ Approach for the Preparation of Polymer Nanocomposite with Multi-functionality

A novel one-step synthetic route, the double in situ approach, is used to produce both TiO2nanoparticles and polymer (PET), and simultaneously forming a nanocomposite with multi-functionality. The method uses the release of water during esterification to hydrolyze titanium (IV) butoxide (Ti(OBu)4) forming nano-TiO2in the polymerization vessel. This new approach is of general significance in the preparation of polymer nanocomposites, and will lead to a new route in the synthesis of multi-functional polymer nanocomposites

Photoluminescence Emission Induced by Localized States in Halide Passivated Colloidal Two-Dimensional WS2 Nanoflakes

Engineering physicochemical properties of two-dimensional transition metal dichalcogenide (2D-TMD) materials by surface manipulation is essential for their practical and large-scale application especially for colloidal 2D-TMDs that are plagued by the unintentional formation of structural defects during the synthetic procedure. However, the available methods to manage surface states of 2D-TMDs in solution-phase are still limited hampering the production of high quality colloidal 2D-TMD inks to be straightforwardly assembled into actual devices. Here, we demonstrate an efficient solution-phase strategy to passivate surface defect states of colloidally synthetized WS2 nanoflakes with halide ligands, resulting in the activation of the photoluminescence emission. Photophysical investigation and density functional theory calculations suggest that halide atoms enable the suppression of non-radiative recombination through the elimination deep gap trap states, and introduce localized states in the energy band structure from which excitons efficiently recombine. Halide passivated WS2 nanoflakes importantly preserve colloidal stability and photoluminescence emission after several weeks of storing in ambient atmosphere, corroborating the potential of our developed 2D-TMD inks

Contractile efficiency of dystrophic mdx mouse muscle: In vivo and ex vivo assessment of adaptation to exercise of functional end points

Progressive weakness is a typical feature of Duchenne muscular dystrophy (DMD) patients and is exacerbated in the benign mdx mouse model by in vivo treadmill exercise. We hypothesized a different threshold for functional adaptation of mdx muscles in response to the duration of the exercise protocol. In vivo weakness was confirmed by grip strength after 4, 8 and 12 weeks of exercise in mdx mice. Torque measurements revealed that exercise-related weakness in mdx mice correlated with the duration of the protocol, while wild-type (wt) mice were stronger. Twitch and tetanic forces of isolated diaphragm and extensor digitorum longus (EDL) muscles, were lower in mdx compared to wt mice. In mdx, both muscle types exhibited greater weakness after a single exercise bout, but only in EDL after a long exercise protocol. As opposite to wt muscles, mdx EDL ones did not show any exercise-induced adaptations against eccentric contraction force drop. qRT-PCR analysis confirmed the maladaptation of genes involved in metabolic and structural remodeling, while damage-related genes remained significantly upregulated and angiogenesis impaired. Phosphorylated AMP kinase level increased only in exercised wt muscle. The severe histopathology and the high levels of muscular TGF-β1 and of plasma matrix metalloproteinase-9 confirmed the persistence of muscle damage in mdx mice. Then, dystrophic muscles showed a partial degree of functional adaptation to chronic exercise, although not sufficient to overcome weakness nor signs of damage. The improved understanding of the complex mechanisms underlying maladaptation of dystrophic muscle paves the way to a better managment of DMD patients

Colloidal TiO₂ Nanorod Films Deposited Using the MAPLE Technique: Role of the Organic Capping and Absence of Characteristic Surface Patterns

Thin films of titanium dioxide (TiO2) nanocrystals, widely acknowledged for their unique physical-chemical properties and functionalities, are used in disparate technological fields, including photovoltaics, sensing, environmental remediation and energy storage. In this paper, the preparation of thin films consisting of anatase-phase TiO2 nanorods deposited using the matrix-assisted pulsed laser evaporation (MAPLE) technique and their characterization in terms of morphology, elemental composition and wettability are presented and discussed. Particular attention is paid to the effects of the laser fluence, varied over a broad range (F = 25, 50, 100 mJ/cm2), and to the role of the capping surfactants bound to the surface of the nanorod precursors. Whereas increasing fluence favored a partial removal of the surface-bound surfactants, a post-growth UV-light-driven photocatalytic treatment of the films was found to be necessary to reduce the incorporated fraction of organics to a further substantial extent. It was noteworthy that, under our experimental conditions, the distinctive surface patterns and roughness that commonly degrade the morphology of films deposited using the MAPLE technique were not observable. This previously unreported experimental evidence was rationalized on the basis of the interaction dynamics between solvent/solute droplets ejected from the laser-irradiated target and the rough surfaces of the growing film

Differentiation of human neuroblastoma cells toward the osteogenic lineage by mTOR inhibitor

Current hypothesis suggest that tumors can originate from adult cells after a process of 'reprogramming' driven by genetic and epigenetic alterations. These cancer cells, called cancer stem cells (CSCs), are responsible for the tumor growth and metastases. To date, the research effort has been directed to the identification, isolation and manipulation of this cell population. Independently of whether tumors were triggered by a reprogramming of gene expression or seeded by stem cells, their energetic metabolism is altered compared with a normal cell, resulting in a high aerobic glycolytic 'Warburg' phenotype and dysregulation of mitochondrial activity. This metabolic alteration is intricately linked to cancer progression.The aim of this work has been to demonstrate the possibility of differentiating a neoplastic cell toward different germ layer lineages, by evaluating the morphological, metabolic and functional changes occurring in this process. The cellular differentiation reported in this study brings to different conclusions from those present in the current literature. We demonstrate that 'in vitro' neuroblastoma cancer cells (chosen as experimental model) are able to differentiate directly into osteoblastic (by rapamycin, an mTOR inhibitor) and hepatic lineage without an intermediate 'stem' cell step. This process seems owing to a synergy among few master molecules, metabolic changes and scaffold presence acting in a concerted way to control the cell fate

Matrix-Assisted Pulsed Laser Evaporation Deposition of Pd Nanoparticles: The Role of Solvent

The formation of Pd nanoparticles (NPs) by matrix-assisted pulsed laser evaporation (MAPLE) of a palladium acetate solution has been studied as a function of the carrier solvent, laser-pulse number, metal precursor concentration and post-deposition thermal heating. Structural and compositional analyses demonstrate that: (i) the conventional MAPLE process can induce self-reduction of the metal salt precursor, thereby leading to the formation of metallic Pd(0) NPs; (ii) the solvent critically determines the size, morphology, and size distribution of the resulting NPs; and (iii) the cumulative effects of laser-pulse number and solute concentration are less influential than the type of solvent used. For diethyl ether-derived samples, a bimodal distribution of NP sizes spanning from ∼1 nm up to 20 nm was obtained. Conversely, by using acetone, a mono-modal distribution of sizes in the ∼1 nm–6 nm range (mean diameter of 1.5±0.7 nm) and a more uniform and densepacked surface coverage (NP coverage was twice as dense as the one obtained with diethyl ether) resulted in. These observations point out that solvents with low dynamical viscosity coefficients and high volatility favor the formation of larger and more broadly dispersed NPs. A general theoretical picture has been proposed to describe the NP formation pathways on account of the solvent properties and the mechanisms underlying the MAPLE process enabled by the technique

MAPLE DEPOSITION OF TiO2 NANORODS: FILM STRUCTURE AND APPLICATIONS

TiO2 nanorods in the brookite phase, having a mean size of 5 nm×50 nm, were prepared through a chemical route. The nanorods were dissolved in pure to luene (0,016 wt % TiO2). The solution was frozen at the liquid-nitrogen temperature and used as a target for the matrix-assisted pulsed laser evaporation (MAPLE) process. Target irradiation was accomplished with a KrF excimer laser (λ=248 nm,τ=20 ns), operated at fluences from F=25 to 350 mJ/cm2. Films were deposited at the repetition rate of 10 Hz using 6000 laser pulses. Film thickness resulted to be ∼ 100 nm at the highest fluence. It was not possible to use a higher number of laser pulses due to the melting of the target (~ 5 mm thick with a diameter of ~ 2.5 mm), even if continuously refrigerated at the LN temperature. Several substrates were used to fully characterize the deposited layers: single-crystal Si wafers, silica slides, Cu carbon-coated grids and alumina interdigital slabs. High-resolution scanning and transmission electron microscopy investigations evidenced the formation of quite rough films incorporating individually distinguishable TiO2 single nanorods. Crystalline spheres were also detected in films, starting from the threshold fluence of 50 mJ/cm2 . Surface density and dimension of the spheres increase with increasing laser fluence. The sphere formation process and the target melting are discussed and attributed to nanosize effects. Films were positively tested as resistive sensors towards very low NO2 concentrations (≅ 1 ppm)