Effects of fiber ellipticity and orientation on dynamic stress concentrations in porous fiber-reinforced composites

Interaction of time harmonic fast longitudinal and shear incident plane waves with an elliptical fiber embedded in a porous elastic matrix is studied. The novel features of Biot dynamic theory of poroelasticity along with the classical method of eigen-function expansion and the pertinent boundary conditions are employed to develop a closed form series solution involving Mathieu and modified Mathieu functions of complex arguments. The complications arising due to the non-orthogonality of angular Mathieu functions corresponding to distinct wave numbers in addition to the problems associated with appearance of additional angular dependent terms in the boundary conditions are all avoided by expansion of the angular Mathieu functions in terms of transcendental functions and subsequent integration, leading to a linear set of independent equations in terms of the unknown scattering coefficients. A MATHEMATICA code is developed for computing the Mathieu functions in terms of complex Fourier coefficients which are themselves calculated by numerically solving appropriate sets of eigen-systems. The analytical results are illustrated with numerical examples in which an elastic fiber of elliptic cross section is insonified by a plane fast compressional or shear wave at normal incidence. The effects of fiber cross sectional ellipticity, angle of incidence (fiber two-dimensional orientation), and incident wave polarization (P, SV, SH) on dynamic stress concentrations are studied in a relatively wide frequency range. Limiting cases are considered and fair agreements with well-known solutions are established.     

Development of smoothed particle hydrodynamics method for modeling active nematics

This article proposes a novel graphics processing unit-based active nematic flow solver based on the smoothed particle hydrodynamics (SPH) method. Nematohydrodynamics equations are discretized using the SPH algorithm. Flow behavior, nematic ordering, topological defects, and vorticity correlation are calculated and discussed in detail. The spectrum of the kinetic energy with respect to the wavenumber is calculated at high particle resolution, and its slope at the different length scales is discussed. To exploit the SPH capabilities, pathlines of nematic particles are evaluated during the simulation. Finally, the mixing behavior of the active nematics is calculated as well and described qualitatively. The effects of two important parameters, namely, activity and elastic constant are investigated. It is shown that the activity intensifies the chaotic mixing nature of the active nematics, while the elastic constant behaves oppositely.     

Synthesis,characterization and catalytic activity studies of Pd-based supported nanoparticle catalyst anchoring on poly(N-vinyl-2-pyrrolidone) modified CMK-3

Pd nanoparticle-poly(N-vinyl-2-pyrrolidone)/CMK-3 (Pd-PVP/CMK-3) composite was prepared by in situ polymerization method which was effectively employed as a novel heterogeneous catalyst for the Suzuki–Miyaura cross-coupling reaction. The physical and chemical properties of Pd nanoparticle-PVP/CMK-3 were investigated using FT-IR, XRD, BET, UV–vis, TEM and TGA techniques. The reaction was carried out between aryl halides and phenylboronic acid in the presence of water at room temperature. The stability of the catalyst was good and could be reused 10 times without much loss of activity in Suzuki–Miyaura reaction.     

Materials for multifunctional balloon catheters with capabilities in cardiac electrophysiological mapping and ablation therapy

Developing advanced surgical tools for minimally invasive procedures represents an activity of central importance to improving human health. A key challenge is in establishing biocompatible interfaces between the classes of semiconductor device and sensor technologies that might be most useful in this context and the soft, curvilinear surfaces of the body. This paper describes a solution based on materials that integrate directly with the thin elastic membranes of otherwise conventional balloon catheters, to provide diverse, multimodal functionality suitable for clinical use. As examples, we present sensors for measuring temperature, flow, tactile, optical and electrophysiological data, together with radiofrequency electrodes for controlled, local ablation of tissue. Use of such 'instrumented' balloon catheters in live animal models illustrates their operation, as well as their specific utility in cardiac ablation therapy. The same concepts can be applied to other substrates of interest, such as surgical gloves.     

Dynamic output feedback stabilization of deterministic finite automata via the semi-tensor product of matrices approach

This paper deals with the dynamic output feedback stabilization problem of deterministic finite automata (DFA).The static form of this problem is defined and so...     

An Insight into Phenomenology of Polytrimethylene Terephthalate Fibrillation

The objective of this work is to analyze the effect of the processing temperature on fibrillation of the dispersed phase and to correlate melt viscoelastic responses to formed morphologies. A blend system of polypropylene (PP)/polytrimethylene terephthalate (PTT) with varying ratios (PP/PTT: 99/1, 94/6, 90/10, and 80/20) is prepared on a co‐rotating twin screw extruder, and then pelletized blend samples are fed into a laboratory mixing extruder to spin monofilaments at three different orifice temperatures of 180, 195, and 240 °C. As revealed by scanning electron microscopy, a nano‐fibrillar morphology forms after employing spinning. Rheological approach performed in the linear region shows a transition from terminal trend into non‐terminal trend in the low‐frequency region when the fibrillar morphology forms, the magnitude and width of which are reflective of the fibril growth. Transient stress measurements prove its capability to enable the blend system to show potentials of morphology development during dynamic tests. Startup of steady shear flow shows that after reaching the percolation concentration of dispersed phase, fibril–fibril coalescence leads to the formation of long fibrils whose contribution to the blend system increases the elasticity of the blend fibers.     

Mechanistic Observation of Interactions between Macrophages and Inorganic Particles with Different Densities

Many different types of inorganic materials are processed into nano/microparticles for medical utilization. The impact of selected key characteristics of these particles, including size, shape, and surface chemistries, on biological systems, is frequently studied in clinical contexts. However, one of the most important basic characteristics of these particles, their density, is yet to be investigated. When the particles are designed for drug delivery, highly mobile macrophages are the major participants in cellular levels that process them in vivo. As such, it is essential to understand the impact of particles’ densities on the mobility of macrophages. Here, inorganic particles with different densities are applied, and their interactions with macrophages studied. A set of these particles are incubated with the macrophages and the outcomes are explored by optical microscopy. This microscopic view provides the understanding of the mechanistic interactions between particles of different densities and macrophages to conclude that the particles’ density can affect the migratory behaviors of macrophages: the higher the density of particles engulfed inside the macrophages, the less mobile the macrophages become. This work is a strong reminder that the density of particles cannot be neglected when they are designed to be utilized in biological applications.