Poly(lactic acid) plasticized with low‐molecular‐weight polyesters: structural,thermal and biodegradability features

Poly(lactic acid) (PLA) was plasticized with ester oligomers having different structure, molecular weight and carboxylic acid content as end‐functionalities. In particular PLA oligomers and a low‐molecular‐weight polyester of adipic acid and 1,2‐propanediol (an adipate‐based derivative) were used and compared. The plasticizing capability was tested and the final structural and thermal properties of PLA matrix were evaluated by correlating the various features to the chemical and physical characteristics of these additives. SEC, DSC, TGA, tensile tests, XRD and SEM results, even after annealing, were collected, and the related data analysed and evaluated with reference to additive starting properties. All the oligoesters were able to generate flexible compounds, but PLA oligomers provided mixtures with reduced structural and thermal stability. Finally, the best performing blend was tested for biodegradability to definitely assess the material suitability for the final application (sustainable packaging). © 2017 Society of Chemical Industry     

Cerebral blood flow in subarachnoid hemorrhage

Myelin protein zero (MPZ, P0) is well known as the adhesion molecule responsible for the compaction of the myelin sheath of peripheral nerves. Mutations are linked to Charcot-Marie-Tooth syndrome type 1B (CMT1B) and the more severe Dejerine-Sottas syndrome (DSS). Three mutations leading to phenotypes of increasing severity (Ser34del/CMT1B, Ser34Cys/DSS, INS663GC/DSS) were expressed in S2 insect cells and resulted in a decreased adhesion capability in correlation with their respective phenotypes.     

Three-Dimensional Simulation of One-Dimensional Transport in Silicon Nanowire Transistors

We present a simulation study of silicon nanowire transistors, based on an in-house code providing the self-consistent solution of Poisson, Schrodinger, and continuity equations on a generic three-dimensional domain. The main assumption, based on the very small nanowire cross section considered, is that an adiabatic approximation can be applied to the Schrodinger equation, so that transport occurs along one-dimensional sub- bands. Different subband transport models are considered, such as ballistic transport, either including quantum tunneling or not, and drift-diffusion. We show that nanowire transistors exhibit good control of short channel effects, and that barrier tunneling is significant in the strong inversion regime even for longer devices, while it is significant in subthreshold only for the shortest channel lengths. Finally, we show that a subband-based transport model allows to reach a very good trade off between physical accuracy of the simulation and computing time.     

Electroreduction of volatile organic halides on activated silver cathodes

The electroreduction of polychloromethanes and polychloroethanes has been studied by means of cyclic voltammetry (CV) and preparative electrolysis experiments in acetonitrile (ACN), dimethylformamide (DMF) and their admixtures with water. Silver has been used as cathode material, on account of our extended experience on its well established electrocatalytic activity toward reductive dehalogenation reactions of organic compounds. Polychloro-methanes and -ethanes are common chlorinated solvents pertaining to the large family of volatile organic halides (VOH), whose high toxicity, or even carcinogenicity, demands careful treatment of contaminated soils, drinking waters and gaseous emissions. The results confirm the electrocatalytic role of silver and suggest a general route for the development of appropriate degradation processes.     

Nonlinear complex-valued extensions of Hebbian learning: an essay

The Hebbian paradigm is perhaps the best-known unsupervised learning theory in connectionism. It has inspired wide research activity in the artificial neural network field because it embodies some interesting properties such as locality and the capability of being applicable to the basic weight-and-sum structure of neuron models. The plain Hebbian principle, however, also presents some inherent theoretical limitations that make it impractical in most cases. Therefore, modifications of the basic Hebbian learning paradigm have been proposed over the past 20 years in order to design profitable signal and data processing algorithms. Such modifications led to the principal component analysis type class of learning rules along with their nonlinear extensions. The aim of this review is primarily to present part of the existing fragmented material in the field of principal component learning within a unified view and contextually to motivate and present extensions of previous works on Hebbian learning to complex-weighted linear neural networks. This work benefits from previous studies on linear signal decomposition by artificial neural networks, nonquadratic component optimization and reconstruction error definition, neural parameters adaptation by constrained optimization of learning criteria of complex-valued arguments, and orthonormality expression via the insertion of topological elements in the networks or by modifying the network learning criterion. In particular, the learning principles considered here and their analysis concern complex-valued principal/minor component/subspace linear/nonlinear rules for complex-weighted neural structures, both feedforward and laterally connected.     

Combined elemental and stem imaging under computer control

A computer-controlled analytical electron microscope has been used to combine digitally acquired elemental maps and STEM images. Real time processing of the electron energy loss and energy-dispersive X-ray signals allows an accurate subtraction of the spectral background at each pixel. The resulting images reflect the true elemental distribution rather than mass thickness variations in the sample. Acquisition of several signals one pixel at a time allows elemental distributions and morphology to be correlated.     

Copper behaviour in acid and alkaline brines—I kinetics of anodic dissolution in 0.5M NaCl and free-corrosion rates in the presence of oxygen

The behaviour of copper has been studied in 0·5M NaCl and at pH values ranging from 2 to 10. In acid solution the anodic dissolution reaction leads to the formation of Cu⁺ ions which can either form soluble complexes or precipitate as solid CuCl depending on their surface concentration. The former situation holds at the free-corrosion potential in the presence of oxygen.In the alkaline range copper behaves, at low current densities (i.e. at low potentials), in the same way as it does in acid solutions; at more anodic potentials a protective layer of solid Cu₂O is formed.     

Antibacterial polyamide obtained by the incorporation of glass microparticles doped with ionic zinc and by zinc oxide nanoparticle: Evaluation with Salmonella typhimurium and Staphylococcus aureus

Food security is very important in all processes executed for the manufacture of meat in meatpacking industries. Meat security can be improved by the use of accessories produced with antimicrobial materials in the manufacture lines. In this work, the antibacterial property was incorporated in the plates of polyamide 6 by the addition of two antibacterial compounds and the antimicrobial characteristics were studied. The antibacterial materials used were glass microparticles doped with ionic zinc and zinc oxide nanoparticles. The antibacterial polyamide 6 was produced containing different percentages of antibacterial compound and its microbiological characterization was realized with the bacteria Salmonella typhimurium and Staphylococcus aureus. The distribution of the antimicrobial compound in polyamide 6 matrix was evaluated by scanning electron microscopy and energy dispersive spectroscopy. Atomic absorption spectrometry was applied to study the migration capacity of the antibacterial compound in the aqueous medium. The results demonstrated that the polyamide 6 containing glass microparticles doped with ionic zinc present better antibacterial action than the polyamide 6 containing zinc oxide nanoparticles. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45005.