Films made from poly(vinyl alcohol‐co‐ethylene) and soluble biopolymers isolated from postharvest tomato plant

Blended films were obtained from polyvinyl alcohol‐co‐ethylene (EVOH) with 52 kDa weight average molecular weight (M_w) and three water soluble biopolymers isolated from exhausted tomato plants hydrolysates. Two biopolymers contained mainly polysaccharides and had 27 and 79 kDa M_w, respectively. The third contained mainly lignin‐like C moieties and had 392 kDa M_W. The films were fabricated with a biopolymer/EVOH w/w ratio ranging from 0.1 to 0.9. All blends had molecular weight and solubility which were substantially different from the starting materials. They were characterized for the chemical nature, and the thermal, rheological, and mechanical properties. Evidence of a chemical reaction between the biopolymers and EVOH was found. Generally, the films exhibited higher mechanical strength but lower strain at break then the neat EVOH. The best performing blended film was fabricated from the 27 kDa M_w polysaccharide. This contained less than 10% biopolymer. It exhibited 1043 MPa Young's modulus and 70% strain at break against 351 MPa modulus and 86% strain for neat EVOH. The results offer scope for investigating biopolymers sourced from other biowastes to understand more the reasons of the observed effects and exploit their full potential to modify or to replace synthetic polymers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41935.     

Improving PCA‐based anomaly detection by using multiple time scale analysis and Kullback–Leibler divergence

The increasing number of network attacks causes growing problems for network operators and users. Thus, detecting anomalous traffic is of primary interest in IP networks management. In this paper, we address the problem considering a method based on PCA for detecting network anomalies. In more detail, this paper presents a new technique that extends the state of the art in PCA‐based anomaly detection. Indeed, by means of multi‐scale analysis and Kullback–Leibler divergence, we are able to obtain great improvements with respect to the performance of the ‘classical’ approach. Moreover, we also introduce a method for identifying the flows responsible for an anomaly detected at the aggregated level. The performance analysis, presented in this paper, demonstrates the effectiveness of the proposed method.Copyright © 2012 John Wiley & Sons, Ltd.     

Stable Alignment of Tautomers at Room Temperature in Porphyrin 2D Layers

A major challenge in molecular electronics is to develop logic devices based on a truly intramolecular switching mechanism. Recently, a new type of molecular device has been proposed where the switching characteristic is mediated by the bistability in the position of the two hydrogen atoms which can occupy different, energetically equivalent positions (tautomerization) in the inner cavity of porphyrins and naphthalocyanines. Up to now, such a reaction has only been exploited at low temperatures and induced or detected through atomic scale manipulation. In addition, the unpredictability of the tautomer orientation currently excludes molecular interconnection to functional electronic circuits. Here, full evidence is provided that, following a newly proposed growth strategy, 2D layers of metal‐free tetraphenylporphyrins (H₂TPP) show frozen tautomerization even at room temperature on macroscopic domains, with the H atoms aligned along a direction settled a priori. This behavior is ascribed to the buckling of the molecule, anchored to the substrate, which removes the degeneracy between the two tautomer alignments. On this basis, a new way to exploit uniaxially oriented H₂TPP tautomers in a first elementary logic device is proposed.     

Averaged strain energy density and J-integral for U- and blunt V-shaped notches under torsion

Analytical solutions for the J-integral and the strain energy density (SED) averaged over a control volume are presented for U- and blunt V-shaped notches under torsion. The influence of the notch tip radius and the notch opening angle are fully included in the new proposed relationships. These expressions take advantage of some recent solutions for the stress fields ahead of blunt notches under Mode III loading and can be seen as a synthesis of the efforts carried out during the last years by the present authors on this topic. Afterwards, the expressions are applied to a recent set of experimental data from cracked, notched and plain specimens tested under torsion at low temperature \((-60\,^{\circ }\hbox {C})\) . The large scatter shown by notched specimens in terms of maximum elastic stresses strongly reduces when the J-integral or the local SED are used in combination with the specific control volumes.     

Carbon Nanostructures for Nanomedicine: Opportunities and Challenges

Carbon nanostructures (e.g., fullerenes, CNTs, graphene, nanohorns, nanodiamonds) play a key role in the development of nanomedicines. Here we analyze opportunities and barriers for their application in clinical settings. In particular, we discuss the unique properties of certain carbon nanostructures that allow for innovative solutions in theranostics, as well as current pitfalls around clinical applications of the EPR effect, the formation of the protein corona, and how functionalization of CNTs is a key tool to modulate their biodistribution and toxicity.     

Luminescent solar concentrators employing new Eu(TTA)3phen‐containing parylene films

New robust luminescent solar concentrators were produced by growing Eu(TTA)₃phen‐containing parylene thin films on poly(methyl methacrylate) slabs through a novel co‐deposition process. As it is the first time that Eu(TTA)₃phen molecules were inserted in parylene matrix, the deposition process was investigated, and the features of the samples were extensively analyzed. Fourier transform infrared spectroscopy analysis demonstrated the integrity of the vacuum‐sublimated Eu(TTA)₃phen molecules. Atomic force microscope analysis showed the very flat surface of the films (Rq = 3.7 nm), which is strategic in luminescent solar concentrators (LSCs) for minimizing the light scattering at the air/film interface. The optical measurements demonstrated that Eu(TTA)₃phen‐containing parylene exhibits higher absorption than the conventional Eu(TTA)₃phen films and the luminescence peaks characteristic of Eu(TTA)₃phen compound. This indicates that the Eu complex is not affected by the matrix interaction thus maintaining its extremely large Stokes shift. Moreover, the parylene matrix improves the luminescence intensity of the films: in fact, under the same absorption, these films show a luminescence intensity more than two times higher than standard Eu(TTA)₃phen ones. The current–voltage (I–V) measurements show that, under the same quantity of Eu(TTA)₃phen, Eu(TTA)₃phen‐containing parylene LSCs produce a current density more than twice as high as LSC without parylene and that their efficiency decreases more than ten times slower than organic‐based LSCs at increasing illuminating area, thus highlighting the feasibility of developing large size LSCs. Copyright © 2014 John Wiley & Sons, Ltd.     

An Unbalanced Synaptic Transmission: Cause or Consequence of the Amyloid Oligomers Neurotoxicity?

Amyloid-β (Aβ) 1-40 and 1-42 peptides are key mediators of synaptic and cognitive dysfunction in Alzheimer’s disease (AD). Whereas in AD, Aβ is found to act as a pro-epileptogenic factor even before plaque formation, amyloid pathology has been detected among patients with epilepsy with increased risk of developing AD. Among Aβ aggregated species, soluble oligomers are suggested to be responsible for most of Aβ’s toxic effects. Aβ oligomers exert extracellular and intracellular toxicity through different mechanisms, including interaction with membrane receptors and the formation of ion-permeable channels in cellular membranes. These damages, linked to an unbalance between excitatory and inhibitory neurotransmission, often result in neuronal hyperexcitability and neural circuit dysfunction, which in turn increase Aβ deposition and facilitate neurodegeneration, resulting in an Aβ-driven vicious loop. In this review, we summarize the most representative literature on the effects that oligomeric Aβ induces on synaptic dysfunction and network disorganization.