Flow Effects in Supramolecular Chirality

There are an increasing number of reports on the emergence of circular dichroic signals when solutions of J-aggregates are vortex-stirred. Some authors claim that the transfer of chirality from the macroscopic stirring vortex occurs at the level of electronic transitions. Others argue that the signal observed is not due to true circular dichroism (CD), but rather that it is an artifact due to combinations of linear polarization contributions. For both interpretations it is necessary to assume that the alignment by effect of flows dominates over the Brownian dynamics. Therefore, the topic belongs to supramolecular chemistry because the alignment in current flows can only occur for relatively large particles with an appropriate shape. The phenomenon is detected by CD spectroscopy, which itself is also the main hindrance, even controversial, in its study and interpretation. However, modern Mueller matrix polarimetry can solve some of the problems. The phenomenon has been explained using different scenarios; however, in some of the systems the experimental evidence only supports the model in which deformation (folding/torsion) of elastic soft-matter yields true CD. Here we discuss the role of the gradient of shear rates in the deformation of nano particles of soft matter to give chiral supramolecular structures, as the first step to explaining the phenomenon.     

Literature review on the ‘Smart Factory’ concept using bibliometric tools

The objective of this paper is to depict a landscape of the scientific literature on the concept of the ‘Smart Factory’, which in recent years is gaining more and more attention from academics and practitioners because of significant innovations in the production systems within the manufacturing sector. To achieve this objective, a dynamic methodology called ‘Systematic Literature Network Analysis (SLNA)’ has been applied. This methodology combines the Systematic Literature Review approach with the analysis of bibliographic networks. The adopted methodology allows complementing traditional content-based literature reviews by extracting quantitative information from bibliographic networks to detect emerging topics, and by revealing the dynamic evolution of the scientific production of a discipline. This dynamic analysis allowed highlighting research directions and critical areas for the development of the ‘Smart Factory’. At the same time, it offers insights on the fields on which companies, associations, politicians and technology providers need to focus in order to allow a real transition towards the implementation of large-scale Smart Factory.     

On the Structural Transition Driven by Band Nesting in?1111?Pnictides

The lattice critical response in REFeAsO (RE=Pr, Nd and Sm) oxypnictides near the orthorhombic-to-tetrahedral structural phase transition is studied using ultra-high-resolution X-ray diffraction in the temperature range 4 to 250 K. The critical exponent of the structural phase transition ?? is found to decrease with decreasing RE size. The ?? values determined to be 0.212, 0.209 and 0.194, respectively, for PrOFeAs, NdOFeAs and SmOFeAs. Temperature hysteresis is observed for all the REFeAsO, with ??T being of the order of 2 to 3 K. The results are discussed in the frame of Fermi surface nesting induced structural transition in the pnictides.     

A particle finite element method for analysis of industrial forming processes

We present a generalized Lagrangian formulation for analysis of industrial forming processes involving thermally coupled interactions between deformable continua. The governing equations for the deformable bodies are written in a unified manner that holds both for fluids and solids. The success of the formulation lays on a residual-based expression of the mass conservation equation obtained using the finite calculus method that provides the necessary stability for quasi/fully incompressible situations. The governing equations are discretized with the FEM via a mixed formulation using simplicial elements with equal linear interpolation for the velocities, the pressure and the temperature. The merits of the formulation are demonstrated in the solution of 2D and 3D thermally-coupled forming processes using the particle finite element method.     

Morphology and viscoelastic properties of melt‐spun HDPE/hydrotalcite nanocomposite fibers

Viscoelastic properties of nanocomposite fibers of high density polyethylene (HDPE) and organically modified hydrotalcite were studied. Neat and nanofilled HDPE fibers (with nanofiller content between 0.5 and 3 wt%) were produced by melt spinning and hot‐drawing at different draw ratios up to 20. Effect of temperature on storage modulus, loss modulus, and creep compliance were compared. Rising nanofiller content and/or drawing ratio accounted for an increase in storage modulus in the glassy (i.e., below the γ transition at −100°C) as well as in the rubbery state of non‐crystalline regions. The α relaxation temperature read‐off for the maximum of the loss modulus peak ranged from 20 to 60°C being dependent on frequency, filler content and draw ratio. Sumita model was successfully applied to evaluate the effective volume fraction of the dispersed phase; maximum fraction of immobilized matrix was observed for the composite with 1 wt% of nanofiller. Creep behavior was evaluated by fitting experimental data with the Burgers model. The addition of a small amount of well‐dispersed hydrotalcite (0.5–1 wt%) had a beneficial effect on the creep resistance of drawn fibers at room temperature as well as at 70°C. TEM analysis evidenced a good dispersion of 0.5% nanofiller in as‐spun fibers and improved interfacial adhesion after drawing. The best mechanical properties were observed for the composition with 1 wt% of hydrotalcite, due to combined effects of nanofiller reinforcement and stiffening produced by hot drawing. POLYM. COMPOS., 288–298, 2016. © 2014 Society of Plastics Engineers     

Dynamic and fluid–structure interaction simulations of bioprosthetic heart valves using parametric design with T-splines and Fung-type material models

This paper builds on a recently developed immersogeometric fluid–structure interaction (FSI) methodology for bioprosthetic heart valve (BHV) modeling and simulation. It enhances the proposed framework in the areas of geometry design and constitutive modeling. With these enhancements, BHV FSI simulations may be performed with greater levels of automation, robustness and physical realism. In addition, the paper presents a comparison between FSI analysis and standalone structural dynamics simulation driven by prescribed transvalvular pressure, the latter being a more common modeling choice for this class of problems. The FSI computation achieved better physiological realism in predicting the valve leaflet deformation than its standalone structural dynamics counterpart.     

A closed‐form expression for the total degradation in OFDM systems

In this paper, building upon Bussgang's theorem, we present a new expression for the total degradation (TD) in OFDM systems. This novel expression is applicable to any high power amplifier (HPA) model. In case of ideal clipping HPA model and for particular realizations of Rapp and Saleh HPA models, it and can be expressed in closed form. It enables a significant speed‐up in computing TD, because it avoids end‐to‐end system simulations. As a consequence, it simplifies the evaluation of TD as a function of the back‐off, yielding a more accurate evaluation of the optimum HPA back‐off (i.e., the back‐off value that minimizes TD). Numerical results show a perfect agreement between the proposed analytical framework and the Monte Carlo simulation results.Copyright © 2014 John Wiley & Sons, Ltd.