Oxygen permeability and the mechanical and thermal properties of (low‐density polyethylene)/poly (ethylene‐co‐vinyl acetate)/organoclay blown film nanocomposites

Various (low‐density polyethylene)/poly(ethylene‐co‐vinyl acetate) (LDPE/EVA) nanocomposites containing organoclay were prepared by one‐ and two‐step procedures through melt blending. The resultant nanocomposites were then processed via the film blowing method. From the morphological point of view, X‐ray diffraction and optical microscopy studies revealed that although a prevalent intercalated morphology was evident in the absence of EVA, a remarkable increase of organoclay interlayer spacing occurred in the EVA‐containing systems. The advantages of the addition of EVA to the LDPE/organoclay nanocomposites were confirmed in terms of oxygen barrier properties. In other words, the oxygen transmission rates of the LDPE/EVA/organoclay systems were significantly lower than that of the LDPE/organoclay sample. The LDPE/EVA/organoclay films had better mechanical properties than their counterparts lacking the EVA, a result which could be attributed to the improvement of the organoclay reinforcement efficiency in the presence of EVA. Differential scanning calorimetry and thermogravimetric analysis experiments were performed to follow the effects of the EVA and/or organoclay on the thermal properties of LDPE. Finally, the films produced from the two‐step‐procedure compound showed enhanced oxygen barrier properties and mechanical behavior as compared to the properties of the films produced via the one‐step procedure. J. VINYL ADDIT. TECHNOL., 19:132–139, 2013. © 2013 Society of Plastics Engineers     

Prediction of restrained shrinkage based on restraint factors in patching repair mortar

Shrinkage of repair material, especially in patching repairs, is the major factor inducing cracking in concrete repairs. Induced cracks in repair materials are due to restrained shrinkage. Although in usual practice, the free shrinkage of the repair mortar is measured, in reality, cracking is not due to free shrinkage. It is well known that cracking is due to restrained shrinkage. It is very hard to measure the restrained shrinkage; therefore, to overcome this problem a restraint factor (R) is used to modify the free shrinkage and come up with the restrained shrinkage. The restraint factor is influenced by the surface and boundary condition.In this study, the restraint factor for patching repair with different boundary conditions (with eaves and without eaves) and surface condition (rough and smooth) of the substrate concrete is investigated.The results show that the restraint factor R lies between 0.1 and 0.94; with an increase of restraint, the restraint factor is increased. In situations with a high level of restraint (eaves at the perimeter and a rough surface of substrate), the average R is 0.83. while with a low level of restraint (without eaves at the perimeter and a smooth surface of the substrate), the average R is 0.22.     

The Emerging Role of Non-Coding RNAs in the Regulation of Virus Replication and Resultant Cellular Pathologies

Non-coding RNAs, particularly lncRNAs and miRNAs, have recently been shown to regulate different steps in viral infections and induction of immune responses against viruses. Expressions of several host and viral lncRNAs have been found to be altered during viral infection. These lncRNAs can exert antiviral function via inhibition of viral infection or stimulation of antiviral immune response. Some other lncRNAs can promote viral replication or suppress antiviral responses. The current review summarizes the interaction between ncRNAs and herpes simplex virus, cytomegalovirus, and Epstein–Barr infections. The data presented in this review helps identify viral-related regulators and proposes novel strategies for the prevention and treatment of viral infection.     

A novel approach for extracting cellulose nanofibers from lignocellulosic biomass by ball milling combined with chemical treatment

Cellulose nanofibers (CNFs) were isolated from kenaf fibers and wheat straw by formic acid (FA)/acetic acid (AA), peroxyformic acid (PFA)/peroxyacetic acid (PAA), hydrogen peroxide (H₂O₂) treatment; and subsequently through ball milling treatment. Characterization of extracted cellulose and cellulose nanofibers was carried out through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA). TEM images showed that extracted cellulose nanofibers had diameter in the range of 8–100 nm. FTIR and XRD results implied that hemicellulose and lignin were mostly removed from lignocellulosic biomass with an increase in crystallinity, and isolation of cellulose nanofibers was successful. The TGA results showed that decomposition temperature of cellulose nanofibers increased by about 27°C when compared with that of untreated lignocellulosic biomass. No significant change was observed in the decomposition temperature of bleached celluloses after ball milling. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42990.     

Encapsulation of nanoparticles by polymerization compounding in a gas/solid fluidized bed reactor

For the first time, a fluidized bed reactor was used for encapsulating nanoparticles by the polymerization compounding approach using Ziegler–Natta catalysts. The polymerization reaction was carried out using a solvent-free process in a gas-phase reactor. This direct gas–solid reaction greatly simplified collecting the particles of interest after polymerization because none of the extra steps often found in encapsulation processes, such as filtering and drying, were performed in this work. The grafting of the catalyst to the original surface of particles was confirmed by X-ray photoelectron spectroscopy. Micrographs obtained by transmission electron microscopy confirmed the presence of a thin layer of polymer, in the order of a few nanometers, around the particles. The thickness of this coating was affected by the operating conditions of the process. The characterization of the modified particles with electron microscopy also revealed that zirconia nanoparticles tend to be coated in an agglomerated state, whereas aluminum particles were mostly individually encapsulated by the polymer. In addition, the effects of temperature and pressure were studied on the encapsulation process and a kinetic analysis was presented based on the available models in the literature. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Comparative studies of solid-state synthesized poly(<Emphasis Type="Italic">o</Emphasis>-methoxyaniline) doped with organic sulfonic acids

Poly(o-methoxyaniline) (POMA) salts doped with organic sulphonic acids (methanesulphonic acid, p-toluenesulphonic acid and dodecylbenzenesulphonic acid) were firstly synthesized by using solid-state polymerization method. The polymers were characterized by Fourier transform Infrared (FTIR) spectra, ultraviolet visible (UV–vis) spectrometry, X-ray diffraction (XRD), Cyclic Voltammetry (CV), and conductivity measurements. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were done to study the morphologies of POMA salts. The results showed that the POMA doped with methanesulphonic acid displayed higher doping level and conductivity. On the contrary, POMA doped with dodecylbenzenesulphonic acid was lower at doping level and conductivity. In accordance with these results, the electrochemical activity was also found to be lower in dodecylbenzenesulphonic acid doped POMA. The results also revealed that the particles of POMA salts have the average size of less than 100 nm.     

An extended radioactive particle tracking method for systems with irregular moving boundaries

The aim of this paper is to present an extension of the original non-intrusive radioactive particle tracking method (RPT) to any geometries with irregular moving boundaries. The principal advantage of RPT over other non-intrusive methods is that it enables the visualization of rather large systems. However, the underlying reconstruction algorithm is limited to cylindrically shaped systems such as fluidized beds and columns. It excludes a wide variety of systems involving multiphase flows such as, for instance, spherical reactors, cyclones and powder silos, hoppers and blenders, all of which are thus currently out of reach of current RPT capabilities. This work addresses these limitations and proposes an approach that solves the inverse map problem to reconstruct the tracer position with time by using a mesh of unstructured cells to discretize the system geometry and kinematics. The anisotropy induced by the gas-solid interface is discussed and taken into account in the proposed model. To show the possibilities and assess the performance of the developed technique, the flow of particles in a 16-qt V-blender is mapped and the mean velocity field is computed.     

Enhanced anti-biofilm activity of facile synthesized silver oxide nanoparticles against K. pneumoniae

Journal of Inorganic and Organometallic Polymers and Materials - The silver oxide nanoparticle was successfully synthesized using floral waste by simple one pot, cost effective method. The complete...     

Modélisation des lignes microrubans supraconductrices couplées déposées sur des substrats diélectriques bianisotropes

In this paper, we model high temperature superconducting coupled microstrip lines printed on bi-anisotropic substrates by the spectral domain Galerkin method. Hence, we have determined the behavior of the effective permittivity for the odd and even modes and the coupling coefficient as a function of several parameters characterizing superconductivity and bi-anisotropy and the geometry of this structure, such as the superconductor material temperature, the distance between the two lines and the optical deviation angles of the dielectric substrates. The validation of the numerical results has been carried out by comparisons with the bibliographic results.     

The infinite time near optimal decentralized regulator problem for singularly perturbed systems: a convex optimization approach

This paper presents LQ decentralized pole location for singularly perturbed systems. The poles are located in a sector included in the left-half complex plane. The singular perturbation method is used to define reduced and well-behaved problems. It is shown that the LQ control problem with pole location in a sector can be solved using the LMI tool. The associated parametrical optimization problem involves a linear cost objective under LMI constraints. The decentralized control problem is then solved in the reduced slow system by just introducing structure constraints on the matrix variables, constraints that do not destroy the linearity and then the convexity of the problem.