Controlling the Morphology of Mesostructured Silicas by Pseudomorphic Transformation: a Route Towards Applications

Micelle‐templated silicas (MTSs) such as MCM‐41 and MCM‐48 feature unique textural properties owing to their uniform distribution of mesopores with tunable sizes. MTS synthesis is relevant to unique self‐assembly processes between surfactants and inorganic matter. The properties of MTSs have been explored in view of applications in fields as diverse as catalysis, chromatography, sensing, photonics, optics, drug delivery, etc. The aim of this contribution is to review, and to highlight by new results, a synthesis strategy we have developed since 2002 to control the particle morphology of MTSs at the micro‐ to millimeter scale, a key step for transferring these materials from the status of beautiful artworks to applicable products. It is based on the concept of pseudomorphic synthesis. Pseudomorphism is well known in the mineral world. It allows preparation of a mineral with a morphology that is not related to its crystallographic symmetry group. The resulting mineral assumes the outward crystal habit of a different mineral. This principle occurs at a nonconstant matter content by using a mineralization solution that exchanges anions (or cations) with an existing (preshaped) solid body, and allows the new structure to precipitate while maintaining the existing morphology. The concept of pseudomorphic transformation is now applied to amorphous preshaped silica particles to produce MTSs with the same morphology, using an alkaline solution to dissolve the silica and reprecipitate it around surfactant micelles into the ordered MTS structures. MTSs with hexagonal and cubic symmetry, different pore sizes, and controlled morphology have been synthesized. The new pseudomorphs have been successfully used as supports in chromatography, a very demanding application in terms of particle size and morphology.     

Metformin and Vitamin D Modulate Inflammation and Autophagy during Adipose-Derived Stem Cell Differentiation

Adipose-derived stem cells (ADSCs) came out from the regenerative medicine landscape for their ability to differentiate into several phenotypes, contributing to tissue regeneration both in vitro and in vivo. Dysregulation in stem cell recruitment and differentiation during adipogenesis is linked to a chronic low-grade inflammation and macrophage infiltration inside the adipose tissue, insulin resistance, cardiovascular disease and obesity. In the present paper we aimed to evaluate the role of metformin and vitamin D, alone or in combination, in modulating inflammation and autophagy in ADSCs during adipogenic commitment. ADSCs were cultured for 21 days in the presence of a specific adipogenic differentiation medium, together with metformin, or vitamin D, or both. We then analyzed the expression of FoxO1 and Heat Shock Proteins (HSP) and the secretion of proinflammatory cytokines IL-6 and TNF-α by ELISA. Autophagy was also assessed by specific Western blot analysis of ATG12, LC3B I, and LC3B II expression. Our results showed the ability of the conditioned media to modulate adipogenic differentiation, finely tuning the inflammatory response and autophagy. We observed a modulation in HSP mRNA levels, and a significant downregulation in cytokine secretion. Taken together, our findings suggest the possible application of these molecules in clinical practice to counteract uncontrolled lipogenesis and prevent obesity and obesity-related metabolic disorders.     

Synthesis of multiwall carbon nanotubes by electric arc discharge in liquid environments

This work reports the experimental results from the production of multiwall carbon nanotubes (MWCN) synthesized by an electric arc discharge performed in liquid environments between pure graphite electrodes. Both liquid nitrogen and deionised water were suitable for a successful synthesis of this form of carbon aggregation. We report a successful synthesis of MWCN by arc discharge submerged in deionised water. Electron microscopy observations of both the reaction products and the surface of the as-synthesized raw material showed the presence of structural degradation of the MWCN, which probably operates after their growth at the cathode. The degradation is tentatively ascribed to a combination of overheating and high current density experienced by the as-synthesized MWNT, which can be caused by the loose structure of the as-deposited material. The damage appeared to be less severe in water environments, probably owing to the better cooling capacity of water relative to liquid nitrogen.     

Simulation of the layer inversion phenomenon in binary liquid--fluidized beds by DEM–CFD with a drag law for polydisperse systems

Liquid-fluidized beds of particular binary mixtures exhibit the layer inversion phenomenon, a peculiar result of the mechanical equilibrium developing in such multiphase systems. Because of the crucial role of the hydrodynamic interaction, these are ideal test cases for assessing fluid-particle models in multi-particle CFD simulations. In the present work the layer inversion phenomenon is reproduced via Discrete Element Method (DEM) simulations, in which the drag force model for polydisperse systems described in Cello et al. (2010) is used. The simulations serve primarily to assess the suitability of the DEM–CFD approach and particularly the validity of the above drag model, although the results available may also prove very useful to investigate the prevailing mechanisms. To analyze a sufficiently broad variety of cases, involving different solid species, size ratios and operating conditions, three systems selected amongst the published literature are considered. The comparison of simulation and experimental observation is carried out in terms of overall bed and mixed layer interface heights, voidage and component distributions along bed height and time evolution of the species centers of mass. Simulations with liquid velocities below, above and at the critical inversion conditions are carried out. Additionally, simulations using a drag force model traditionally used for monodisperse beds are reported for comparison. The results not only demonstrate the importance of correctly accounting for the local size distribution in the bed, but also prove the validity of the overall computational approach. The predictions of the simulations are in good to excellent agreement with experiments, depending on the system considered, both in terms of critical velocity and, most notably, expansion of the individual components in the bed. The analysis of the hydrodynamics in the bed allows to investigate the local particle flow field, highlighting the presence of a steady irregular motion of the solids in apparently chaotic vortices continuously forming and disappearing, which is thought to be the mechanism responsible for mixing. The fluid–particle interaction forces exhibit a constant profile along bed height, even in the presence of a strongly non-uniform concentration profile.     

Overexpression of the RON gene in human breast carcinoma

Constitutive activation of the RON gene, known to code for the tyrosine-kinase receptor for Macrophage Stimulating Protein (also known as Scatter Factor 2), has been shown to induce invasive-metastatic phenotype in vitro. As yet, nothing is known about the expression of this novel member of the MET-oncogene family in spontaneously occurring human cancers. Here we report that Ron is expressed at abnormally high levels in about 50% primary breast carcinomas (35/74 patients). Among these, the expression is increased more than 20-fold in 12 cases and the overexpressed protein is constitutively phosphorylated on tyrosine residues. Notably, Ron is only barely detectable in epithelial cells of the mammary gland, and its expression remains unchanged in benign breast lesions (including adenomas and papillomas). Overexpression was observed in different histotypic variants of carcinomas; it is associated with the disease at any stage and correlates with the post-menopausal status. In breast carcinoma cells grown in vitro, activation of the Ron receptor resulted in proliferation, migration and invasion through reconstituted basement membranes. Altogether, these data suggest a role for the RON gene in progression of human breast carcinomas to the invasive-metastatic phenotype.     

Avoiding cross-bifix-free binary words

In this paper we study the construction and the enumeration of binary words in $\{0,1\}^*$ having more 1’s than 0’s and avoiding a set of cross-bifix-free patterns. We give a particular succession rule, called jumping and marked succession rule, which describes the growth of such words according to their number of ones. Moreover, the problem of associating a word to a path in the generating tree obtained by the succession rule is solved by introducing an algorithm which constructs all binary words having more 1’s than 0’s and then kills those containing the forbidden patterns. Finally, we give the generating function of such words according to the number of ones.     

Does hue affect the perception of grayness?

Although gray is defined as an achromatic color sensation varying only in lightness, in practice, grayness can be tinged by any hue within a limited range of chroma. Given the fact that preferred perceived white and black are slightly chromatic, the hypothesis tested in this study is that the preferred perceived object gray is also slightly chromatic. Two psychophysical experiments were carried out to test this hypothesis. A total of 56 color normal subjects assessed 27 different gray patches that varied mainly in hue, in three separate trials. Subjects selected a subset of samples (10 in the first experiment and five in the second experiment) that were considered “most gray” resulting in 168 selected sets of samples. Subjects then ranked their selected subset of samples from most to least gray. A total of 1225 assessments were thus obtained (750 assessments in the first experiment and 465 in the second experiment). Results from both experiments were in good agreement and indicate that greenish blue grays in the range of 190° to 235° of CIELAB hue angle were selected as most gray, thus indicating that the perception of grayness is influenced by hue. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 374–382, 2015     

Enhanced utilisation of nonmarketable fish: physical,nutritional and sensory properties of ‘clean label’ fish burgers

Four ‘clean label’ formulations for fish burgers made with mechanically separated fish meat were characterised in sensory, textural and chemical terms. The formulations differed in the ratios of European sea bass to rainbow trout (50:50 and 30:70) and the ratios of fish to potato flakes (dry matter ratio, DMR: 2.5:1 and 1.5:1). The sensory profile was mainly influenced by DMR. Recipes with the higher DMR were positively correlated with sandy, dry and crusty attributes, salty taste and overall flavour. Soft texture was perceived for recipes with the lower DMR, although no differences in texture were detected by a texturometer. Lowering DMR increased ash and water content and decreased protein content, as expected. The results indicated that 100 g of burger provided more essential fatty acids than the recommended daily intake, irrespective of formulation. In conclusion, multiple factor analysis indicated that the main changes detected and perceived were due to DMR.