Highly bright and photostable cyanine dye-doped silica nanoparticles for optical imaging: Photophysical characterization and cell tests

Spherical silica nanoparticles containing fluorescent trimethine indocyanine dyes (λ_abs = 547 nm, λ_em = 570 nm) were prepared using a water-in-oil microemulsion method. The nanoparticles were of 50 nm diameter and were almost monodispersed in aqueous solution at pH 5.5. Entrapment of dye molecules in the silica matrix stabilised photoemission over several hours of continuous irradiation. The photoemission intensity of the indocyanine was increased 13-fold over that recorded in solution. As each nanoparticle contained 110 dye molecules, the photoemission brightness of each particle was enhanced by three orders of magnitude. The fluorescent nanoparticles have been tested as imaging tools in in vitro tests. As an example of non-macrophagic cells, a highly differentiated neuronal cell line (GT1-7) was used and the results showed that the prepared nanoparticles can be incorporated into these cells with no apparent toxicity for up to three days.     

An effective multipurpose building block for 3D electropolymerisation: 2,2′-Bis(2,2′-bithiophene-5-yl)-3,3′-bithianaphthene

Novel thiophene-based oligomer, 2,2′-bis(2,2′-bithiophene-5-yl)-3,3′-bithianaphthene (TX), was designed and synthesized, and its electrochemical and spectral properties characterised. TX was readily polymerised electrochemically to form well organized conducting homopolymer films on various solid electrode substrates. Moreover, it was successfully used for deposition by electropolymerisation of electrochemically active thin films of co-polymers with three different monomers of functionalised bis(2,2′-bithienyl)methane derivatives. It appeared that TX was an effective crosslinker and 3D promoter in these electropolymerisations involving co-monomers intrinsically showing limited aptitude for the electropolymerisation or forming polymer films of low conductivity. This attractive TX ability stems from combination of its (i) high conjugation efficiency in each of the two planar moieties, (ii) intrinsic 3D structure on account of the presence of the central node, and (iii) intrinsic regioselectivity in electropolymerisation on account of the positions of the two available free α-thiophene sites.     

Electrospinning: A Novel Method to Incorporate POSS Into a Polymer Matrix

The effectiveness of electrospinning as a simple approach to disperse POSS into a polymer matrix at a nm‐level has been assessed. Electrospun and cast films were prepared by dissolving CA and epoxycyclohexylisobutyl POSS in the solvent mixture acetone/DMAc. The membranes were characterized by SEM, TEM and WAXD. Whereas films produced by casting showed µm‐sized POSS crystals, thus suggesting a small affinity between the polymer matrix and the POSS molecules, those prepared by electrospinning were characterized by a nanometric POSS distribution. This is explained by considering the peculiar solvent evaporation mechanism, occurring during the electrospinning process, which allows to produce nanofibers characterized by a silsesquioxane dispersion similar to that present in solution.

     

Metal Triflates Incorporated in Mesoporous Catalysts for Green Synthesis of Fine Chemicals

Strong Lewis acid SnTf-MCM-41 and SnTf-UVM-7 catalysts with unimodal and bimodal pore systems were prepared in a two-step synthesis in which the triflic acid (Tf) was incorporated into previously synthesized mesoporous tin-containing silicas. The Sn incorporation inside the pore walls was carried out through the Atrane method. The SnTf-UVM-7 catalysts were prepared by aggregating nanometric mesoporous particles defining a hierarchic textural-type additional pore system. Catalysts with different Si/Sn ratios in the range 21.8–50.8 for SnTf-MCM-41 and 18.4 for SnTf-UVM-7 were found to be efficient catalysts for the acylation of aromatics and heteroaromatics. Under microwave irradiation the reaction was possible even with acetic acid. The selectivity to the desired product (o-hydroxyacetophenone for phenol) or the unfavored three-substituted five ring heterocycles was dramatically increased under these conditions. The process is green, environmentally safe, and heterogeneous.     

Cellulose nanocomposites based on silane reinforced 3-butynoate-substituted zirconium-oxocluster copolymers: Mechanical,thermal and hydrophobic properties

Silica based cellulose nanocomposites obtained from (3-mercaptopropyl)trimethoxysilane or vinyltrimethoxysilane and 3-butynoate-substituted zirconium-oxoclusters were prepared and their surface morphology, wettability, and thermo-mechanical properties were studied. The composites showed a hydrophobic surface, high strength, and resistance to thermal degradation and aging; in comparison to the untreated paper they required a higher temperature to activate combustion and generated less heat during all thermal processes.     

Texture anisotropy technique in brain degenerative diseases

Structural alterations anisotropy-based measured for different areas for the most common types of dementia diseases could be a biomarker of brain impairment. The current work aims to assess whether texture anisotropy can discriminate both healthy versus Alzheimer’s and Pick’s patients based on regional evaluation while maintaining high predictive power. The investigated area is reduced from the whole-brain surface to three major lobes (i.e., frontal, temporal and parietal). A predictive model was proposed to associate a disease with a specific area in the brain based on the anisotropy values. Simultaneous analysis of 1680 measurements from 105 brain magnetic resonance images acquired as T2w and PD sequences was performed to establish the significance of the model. The cerebral calcinosis disease has been used as artificial ground truth. The association based on textural anisotropy between targeted diseases and control patients was performed by using Pearson’s correlation coefficients. A new proposed consistency index investigated the texture anisotropy relevance for all image’s types and all analyzed classes and regions. The validation study is based on area under the receiver-operating characteristic curve that depicted the overall diagnostic performance of the texture anisotropy in each region. The proposed model demonstrated that texture anisotropy is accurate solution in diagnosis of Alzheimer’s and Pick’s diseases when the investigated area is reduced to major lobes, with sensitivity >90% and specificity >80%.

     

Magnetic resonance butterfly coils: Design and application for hyperpolarized C studies

Hyperpolarized ¹³C magnetic resonance spectroscopy in pig models enables cardiac metabolism assessment and provides a powerful tool for heart physiology studies, although the low molar concentration of derivate metabolites gives rise to technological limitations in terms of data quality. The design of dedicated coils capable of providing large field of view with high Signal-to-Noise Ratio (SNR) data is of fundamental importance.     

Effect of the fuel injection strategy on the combustion process in a PFI boosted spark-ignition engine

In this paper, the effect of different fuel injection strategies on the combustion process was investigated in a boosted port fuel injection spark-ignition engine. The experiments were performed on a partially transparent single-cylinder engine, equipped with a four-valve head and boost device. Single and double fuel injection strategies were tested in the open-valve condition. Moreover, two fuel injection pressures were considered. Optical techniques based on 2D-digital imaging were used to follow the flame propagation in the combustion chamber. In particular, the diffusion-controlled flames near valves and on cylinder walls due to the fuel film burning were studied. Two-colour pyrometry was employed to measure soot concentration. In-cylinder optical investigations were correlated to the engine parameters and to the exhaust emissions.