A Not-a-Knot meshless method using radial basis functions and predictor–corrector scheme to the numerical solution of improved Boussinesq equation

A numerical simulation of the improved Boussinesq (IBq) equation is obtained using collocation and approximating the solution by radial basis functions (RBFs) based on the third-order time discretization. To avoid solving the nonlinear system, a predictor–corrector scheme is proposed and the Not-a-Knot method is used to improve the accuracy in the boundary. The method is tested on two problems taken from the literature: propagation of a solitary wave and interaction of two solitary waves. The results of numerical experiments are compared with analytical solution and with those of other recently published methods to confirm the accuracy and efficiency of the new scheme presented in this paper.     

Robust and efficient surface reconstruction from contours

We propose a new approach for surface recovery from planar sectional contours. The surface is reconstructed based on the so-called “equal importance criterion,” which suggests that every point in the region contributes equally to the reconstruction process. The problem is then formulated in terms of a partial differential equation, and the solution is efficiently calculated from distance transformation. To make the algorithm valid for different application purposes, both the isosurface and the primitive representations of the object surface are derived. The isosurface is constructed by means of a partial differential equation, which can be solved iteratively. The traditional distance interpolating method, which was used by several researchers for surface reconstruction, is an approximate solution of the equation. The primitive representations are approximated by Voronoi diagram transformation of the surface space. Isosurfaces have the advantage that subsequent geometric analysis of the object can be easily carried out while primitive representation is easy to visualize. The proposed technique allows for surface recovery at any desired resolution, thus avoiding the inherent problems of correspondence, tiling, and branching.     

Amylopectin Multiple Aldehyde Crosslinked Hydrogel as an Injectable and Self‐Healing Cell Carrier for Bone Tissue Engineering

Despite excellent processing and biological properties of gelatin for use as a cell carrier, none of the gelatin‐based hydrogel cell carriers reported to date offer all characteristics including quick formation, injectability, self‐healing, and durability, which are simultaneously required for an ideal system. Here, a gelatin‐based hydrogel with dynamic Schiff base linkages, so‐called “dynamic hydrogel,” as an injectable cell carrier consisting of gelatin and amylopectin multiple aldehyde (AMPA), with all the required characteristics is reported. Biocompatibility and osteoinductivity of the hydrogel are verified through the culture of human bone marrow‐derived mesenchymal stem cells (hBMSCs). As live/dead results show, hBMSCs are alive and highly viable ≈85–90% within the hydrogel after 5 days. According to bromodeoxyuridine cell proliferation assay, a significant increase in the number of the cells seeded in the hydrogel confirms its clinical significance for cell therapy. Most importantly, histological visualization using Mason's Trichrome staining indicates secretion of extracellular matrix around the cells loaded in the hydrogel and also expression level evaluation of the crucial osteogenic markers, confirms that the hydrogel can provide osteoinductive support for osteocyte differentiation of hBMSCs after 14 days. Therefore, this hydrogel provides more progress on the path toward bone tissue engineering and further treatment of bone diseases.     

Synthesis of antistatic hybrid nanocomposite coatings using surface modified indium tin oxide (ITO) nanoparticles

Several antistatic nanocomposite hybrid coatings based on epoxy-silane developed by sol–gel method are studied. The hybrid sols are prepared by hydrolysis and condensation of GPTMS and TMOS precursors in the presence of an acid, as catalyst, and EDA as curing agent. Considering their good electrical conductivity, indium tin oxide (ITO) nanoparticles are used as antistatic agents. To improve the distribution/dispersion of ITO nanoparticles in the polymer matrix, the surface of nanoparticles is modified with silane groups (m-ITO). The antistatic properties of the coatings, containing various amounts of m-ITO nanoparticles, are investigated through surface electrical resistivity measurements. FTIR is used to screen the reaction of epoxy groups and the effect of EDA on crosslinking in the hybrid coatings. Morphology, nanoparticle distribution and surface roughness of the coatings are studied through SEM and AFM microscopy techniques. Also, homogeneous distribution of ITO nanoparticles within the polymer matrix is confirmed by EDXA elemental mapping. The cubic shape and nanometric size of the nanoparticles in the hybrid coatings are monitored by transmission electron microscopy (TEM).     

New algorithm for the numerical simulation of two-phase stratified gas–liquid flow and its application for analyzing the Kelvin–Helmholtz instability criterion with respect to wavelength effect

In this article, the transient condition of two-phase stratified gas–liquid flow was investigated using numerical simulation. The basis of the method involves the one-space dimensional transient solution of the governing equations using the two-fluid model. In this paper, an analogy between the SIMPLE algorithm in two-space dimensional single-phase flow and one-space dimensional two-phase stratified flow is established through the application of a special algorithm created to solve the conservation equations. After the modeling was established and justified, wave growth was examined in two-phase stratified flow in a horizontal duct. The results were then compared with the results of the previously published articles. The results show that the classical criterion for the Kelvin–Helmholtz (K–H) instability is consistent when the long wavelength with small amplitude is considered. In this case (of the K–H instability criterion), the wavelength effect on this instability and pressure variation on the two phases interface was consistent with prior researchers’ correlations. However, as the wavelengths decreased, the results indicated that the K–H instability criterion is over-predicted and must be modified. The application of the present numerical simulation method improved the results, and the consistency with the analytical solution is higher in comparison with other well-known computer codes.     

Hydrophilicity and morphological investigation of polycarbonate irradiated by ArF excimer laser

Lasers are used to modify polymeric materials. In this work, a number of polycarbonate (PC) pieces were exposed by ArF excimer laser, 193 nm, at various UV doses from 10 to 100 J/cm² with 50-500 mJ/pulse at 10 Hz pulse repetition rate. Morphology of PC has been investigated by scanning electron microscope (SEM) at three regimes pre-ablation, slow and fast ablation. SEM identifies that the conical defects are created on the polymer surface to grow opposite to the direction of laser irradiation. It increases the superficial absorptivity of the material dependent on the ArF laser induced conical microstructure geometry. The contact angle measurement was performed here, in order to determine the hydrophilicity of the irradiated polymer at various coherent doses. It is shown that the contact angle of PC samples which are exposed to the ArF laser significantly alters with UV dose below 7 J/cm².     

BioSig: an imaging bioinformatic system for studying phenomics

Using genomic information to understand complex organisms requires comprehensive knowledge of the dynamics of phenotype generation and maintenance. A phenotype results from selective expression of the genome, creating a history of the cell and its response to the extracellular environment. Defining cell phenomes requires tracking the kinetics and quantities of multiple constituent proteins, their cellular context, and their morphological features in large populations. The paper considers how the BioSig imaging bioinformatic system for characterizing phenomics answers these challenges. The BioSig approach to microscopy and quantitative image analysis helps to build a more detailed picture of the signaling that occurs between cells as a response to exogenous stimulus such as radiation or as a consequence of endogenous programs leading to biological functions. The system provides a data model for capturing experimental annotations and variables, computational techniques for summarizing large numbers of images, and a distributed architecture that facilitates distant collaboration     

Structural and mechanical evaluation of the effect of oxygen boost diffusion on a gamma based titanium aluminide of Ti-45Al-2Nb-2Mn-1B

Air oxidation, vacuum heating and a subsequent oxidation (DT treatment) of Ti-45Al-2Nb-2Mn-1B (at.%) titanium aluminide resulted in several oxide layers and a hard Ti₃Al as an interlayer between the substrate and the oxide layers.Surface characterization was carried out using X-Ray Diffraction (XRD), Glow Discharge Spectroscopy (GDS), electron microscopy, microhardness tests, ball-on-disk tests and profilometry.The compositions of oxides were TiO₂ and Al₂O₃ at the surface layers after final air oxidation and Ti₃Al interlayer was enriched with oxygen.Multi step treatment improved the hardness of treated surfaces significantly in comparison with that of the sample thermally oxidized only at 800 °C (TO treatment). The hard Ti₃Al interlayer containing soluble oxygen supported the top oxide layers of the DT treated sample against indentation. Such supporting layer did not form between the soft substrate materials and the oxide layers of TO treated materials.The mean value and variation of friction coefficient on multi step treated surfaces were less than that of the untreated material. The friction behavior of worn surfaces on the multi step treated material against steel and WC-Co ball sliders was rather smoother than that of TO treated samples.Top surface layers of TO treated material were removed at very shorter sliding distances and lower loads than those of DT treated surfaces against both steel and tungsten carbide sliders.     

Electrical Conductivity of V2O5–TeO2–Sb Glasses at Low Temperatures

Semiconducting glasses of the type 40TeO₂–(60 ? x) V₂O₅–xSb were prepared by rapid melt quenching and their dc electrical conductivity was measured in the temperature range 180–296 K. For these glassy samples, the dc electrical conductivity ranged from 2.26 × 10^?7  S cm^?1 to 1.11 × 10^?5 S cm^?1 at 296 K, indicating the conductivity is enhanced by increasing the V₂O₅ content. These experimental results could be explained on the basis of different mechanisms (based on polaron-hopping theory) in the different temperature regions. At temperatures above Θ _D/2 (where Θ _D is the Debye temperature), the non-adiabatic small polaron hopping (NASPH) model is consistent with the data, whereas at temperatures below Θ _D/2, a T ^?1/4 dependence of the conductivity indicative of the variable range hopping (VRH) mechanism is dominant. For all these glasses crossover from SPH to VRH conduction was observed at a characteristic temperature T _R ≤ Θ _D/2. In this study, the hopping carrier density and carrier mobility were determined at different temperatures. N (E _F), the density of states at (or near) the Fermi level, was also determined from the Mott variables; the results were dependent on V₂O₅ content.     

Effect of microwave plasma torch on the pyrolysis fuel oil in the presence of methane and ethane to increase hydrogen production

Pyrolysis fuel oil (PFO) processing by microwave plasma torch was developed for the production of hydrogen. The PFO cracking process was performed at atmospheric pressure in the absence of catalyst and effect of plasma gas on the production rate of hydrogen and light hydrocarbons (C₂–C₄) was evaluated. In the first step, effect of the applied power and the working gas flow rate was investigated. In the second step, the applied power and working gas rate were set to 650 W and 4000 sccm, respectively, which were provided by combining methane or ethane as 0%, 2.5%, 7.5%, and 20% with argon. By increasing the percentage of the existing methane in argon, production rate of the sum of the light hydrocarbons was increased and that of hydrogen was reduced, but it was more than the case when argon was applied alone. By increasing ethane percentage, hydrogen production and light hydrocarbon rate were increased. The best conditions of the plasma gas for producing hydrogen at the power of 650 W were obtained as 5CC PFO feed, 2500 sccm (80%) argon, and 500 sccm (20%). The hydrogen production rate in optimized conditions was 2343.16SCCM with selectivity of 84.41%. Sum of the obtained hydrocarbons in this test was 434.25 sccm. Another parameter in the present study was the feed volume processed by plasma. In this case, 5 cc, 3 cc, and 1 cc of the feed were tested when the plasma gas was 3000 sccm argon with the power of 650 W. The results showed that, by increasing the feed, the products were increased. In the processing of 5 cc feed with plasma, 896.41 sccm hydrogen and 61 sccm light hydrocarbon were produced.