Plasticizing and Reinforcing Features of Siloxane Domains in Amine‐Cured Epoxy/Silica Hybrids

Organic/inorganic hybrid materials comprising an amine‐epoxide network and siloxane domains are produced by the sol/gel method. The presence of both plasticizing flexible linear siloxane sequences and reinforcing nanosized silica particles and branched silsesquioxanes (SSQO) structures is confirmed by ²⁹Si NMR and SAXS analysis. The hybrids display simultaneously a monotonical reduction in T_g and an increase in rubbery plateau modulus with increasing siloxane content. At the same time, nanoindentation tests reveal an improved resistance to plastic deformation. The effect of siloxane content on the values of the rubbery plateau modulus is evaluated through the EBM model for blends and composites exhibiting the characteristic co‐continuity of the two constituent phases.

     

A Rapid Prototyping Scenario for Power Factor Control in Permanent Magnet Synchronous Motor Drives: Control Solutions for Interleaved Boost Converters

Rapid prototyping of control is one of the most important technologies for designers and researchers to shorten design and testing of control algorithms. This article presents power electronics opportunities provided by PSIM software and a high performance digital signal processing. The field of application examined is motor control and switching mode power supplies. In particular, more emphasis to the theoretical treatment of linear and non-linear power factor controllers has been given, and the performances of examined algorithms in both the simulated and real world have been verified. Finally, good matching between the results of these two configurations has been documented.     

Direct ink writing of silica-carbon-calcite composite scaffolds from a silicone resin and fillers

Calcite-based composite scaffolds have been successfully 3D-printed by direct ink writing, starting from a paste comprising a silicone polymer and calcite (CaCO₃) powders. The firing in nitrogen, at 600?°C, after preliminary cross-linking step at 350?°C, determined the transformation of the polymer matrix into a silica-carbon nano-composite, embedding unreacted calcite particles. Compared to previously developed silica-calcite scaffolds, obtained after firing in air, the new composites exhibited a significant strength improvement (up to ～10?MPa, for a total open porosity of 56%). The new formulation did not compromise the in vitro bioactivity and the biocompatibility of the scaffolds, as shown by dissolution studies in SBF and preliminary cell culture tests, with human fibroblasts. Due to the simplicity of the processing and the outstanding mechanical performances, the developed scaffolds are promising candidates for bone tissue engineering applications.     

Nanostructured biomaterials for tissue engineered bone tissue reconstruction

Bone tissue engineering strategies are emerging as attractive alternatives to autografts and allografts in bone tissue reconstruction, in particular thanks to their association with nanotechnologies. Nanostructured biomaterials, indeed, mimic the extracellular matrix (ECM) of the natural bone, creating an artificial microenvironment that promotes cell adhesion, proliferation and differentiation. At the same time, the possibility to easily isolate mesenchymal stem cells (MSCs) from different adult tissues together with their multi-lineage differentiation potential makes them an interesting tool in the field of bone tissue engineering. This review gives an overview of the most promising nanostructured biomaterials, used alone or in combination with MSCs, which could in future be employed as bone substitutes. Recent works indicate that composite scaffolds made of ceramics/metals or ceramics/polymers are undoubtedly more effective than the single counterparts in terms of osteoconductivity, osteogenicity and osteoinductivity. A better understanding of the interactions between MSCs and nanostructured biomaterials will surely contribute to the progress of bone tissue engineering.     

Bioinformatics Tools and Novel Challenges in Long Non-Coding RNAs (lncRNAs) Functional Analysis

The advent of next generation sequencing revealed that a fraction of transcribed RNAs (short and long RNAs) is non-coding. Long non-coding RNAs (lncRNAs) have a crucial role in regulating gene expression and in epigenetics (chromatin and histones remodeling). LncRNAs may have different roles: gene activators (signaling), repressors (decoy), cis and trans gene expression regulators (guides) and chromatin modificators (scaffolds) without the need to be mutually exclusive. LncRNAs are also implicated in a number of diseases. The huge amount of inhomogeneous data produced so far poses several bioinformatics challenges spanning from the simple annotation to the more complex functional annotation. In this review, we report and discuss several bioinformatics resources freely available and dealing with the study of lncRNAs. To our knowledge, this is the first review summarizing all the available bioinformatics resources on lncRNAs appeared in the literature after the completion of the human genome project. Therefore, the aim of this review is to provide a little guide for biologists and bioinformaticians looking for dedicated resources, public repositories and other tools for lncRNAs functional analysis.     

Plant-Derived Semiochemicals as Contact Host Location Stimuli for a Parasitoid of Leafminers

We elucidated the source of chemical cues in a system where the host is concealed and the parasitoid has no direct contact with the host larvae or its frass. Behavioral bioassays with Pholetesor bicolor, a larval parasitoid of the apple leafminer, Phyllonorycter pomonella, showed that the herbivore-damaged leaf epidermis (mine) elicited ovipositional probing of parasitoid females. Probing on larvae or frass was seldom observed. Hexane extracts of mines elicited the same ovipositional probing behavior while no response was observed with hexane extracts of larvae or frass or with methanol and diethyl ether extracts. In addition, gas chromatographic analyses showed qualitatively and quantitatively different profiles of these three components of the host-plant complex. By far the highest quantities and also the highest number of compounds was recovered from mine extracts. Identified compounds in the mine included six alkanes (n-C ₂₇ to n-C ₃₃) and squalene (C₃₀H₅₀). A synthetic blend of the seven compounds was slightly less active in biotests than the equivalent natural blend, as shown by a time delay in female response. We conclude that this leafminer parasitoid does not rely on host-derived kairomones but instead uses plant-derived semiochemicals for host location and ovipositional probing behavior.     

Lineage‐Specific Commitment of Stem Cells with Organic and Graphene Oxide–Functionalized Nanofibers

Controlling the differentiation to certain lineages is the main goal of current stem cell research, which might exploit new routes based on the interaction of cells with nanomaterials. Here it is shown that primary neurospheres from dental pulp stem cells grown on combinatorial surfaces with different fibrous morphology and graphene oxide functionalization exhibit different differentiation propensity. The developed materials strongly influence the stem cell fate, as highlighted by morphological, immunofluorescence, molecular biology, and functional analyses. Instructive cues lead to the increased expression of markers that are characteristic of selective differentiation into osteoblasts, glial cells, fibroblasts, and neurons even in basal medium conditions, and randomly oriented fibers are found to revert neuronal precommitment and to trigger osteoblastic differentiation. Graphene oxide coatings lead instead to the relatively enhanced expression of genes typical of either glial or neuronal commitment, depending on the underlying nanofibrous morphology. The mechanisms addressing cell fate are investigated, highlighting the correlation of wetting anisotropy and protein adsorption capacity of different surfaces, ultimate cell conformational changes reflected by skeletal and nuclear elongation, and directed cell commitment. Cues from the different surfaces are therefore lineage‐specific, unveiling remarkable potentialities for cellular programming by means of nanomaterials.     

Dielectric Properties of Sustainable Nanocomposites Based on Zein Protein and Lignin for Biodegradable Insulators

Two types of lignin, alkali lignin and lignosulfonic acid sodium salt, are blended into thermoplastic zein through melt mixing in order to develop biodegradable insulator materials for multifunctional applications in electronics. The effects of lignin type and content on the dielectric properties of the resulting bio‐nanocomposites are investigated. The results indicate that, by modifying the structural arrangement of the zein with the use of lignin, it is possible to obtain bio‐nanocomposites characterized by tunable dielectric properties. The bio‐nanocomposites containing low amounts of lignin derivatives exhibit extensive protein structural changes together with a modification of the dielectric properties compared to the pristine thermoplastic zein. Changes in the dielectric properties of these systems are also observed to change over time, indicating a loss of plasticizer, as is evident by a decrease in the glass‐transition temperature. At high frequencies, the resulting values of the dielectric permittivity and of the loss tangent demonstrate that the bio‐nanocomposite can be used as biodegradable dielectric material for transient (temporary) electronics.     

Preparation and evaluation of polymer/clay nanocomposite surface treatments for concrete durability enhancement

In this work, the effectiveness of nanocomposite surface treatments as protective systems for concrete substrates was evaluated. The study was carried out on hybrid organic-inorganic systems prepared by solvent intercalation of an organomodified montmorillonite into two commercial resins: a coating and a pore liner. The obtained nanocomposite systems at 2, 4 and 6 wt% of nanoclay were applied on concrete substrates and characterized to evaluate their protection performances in comparison with the plain resins. In particular, the effect of the different treatments on liquid and vapor water barrier properties, salt attack resistance, porosity, surfaces water repellency and color changes were analyzed. The results demonstrated that the nanoclay addition can significantly improve the protection effectiveness of both the used plain resins, with chromatic modifications undetectable to the naked eye. However, the extent of the obtained gain strongly depends on the chemical nature and therefore on the mechanisms of action of the matrix.     

Zinc porphyrin-driven assembly of gold nanofingers

Nanofingers of gold covered by porphyrins are prepared by a combination of atomic manipulation and surface self-organization. A submonolayer of zinc(II) 5,10,15,20-tetrakis(4-tert-butylphenyl)-porphyrin (ZnTBPP) axially ligated to a self-assembled monolayer of 4-aminothiophenol (4-ATP) on Au(111) is prepared and studied using a combination of ultrahigh vacuum techniques. Under the electric field produced by the STM tip, the relatively weakly bound Au surface atoms along the discommensuration lines become mobile due to the strong bond to 4-ATP, while the tendency of the porphyrins towards self-assembly result in a collective motion of gold clusters. The clusters diffuse onto the surface following well-defined pathways along the [112] direction and then reach the step edges where they assembled, thus forming nanofingers. First-principles density functional theory calculations demonstrate the reduction of the binding energies between the surface gold clusters and the substrate induced by adsorption of thiols. Scanning tunneling microscopy images show assemblies across three adjacent discommensuration lines of the Au(111)-(22 x square root 3) reconstruction, which collectively diffuse along these lines to form islands nucleated at step edges.