Measurements in Situ and Spectral Analysis of Wind Flow Effects on Overhead Transmission Lines

In the paper an important issue of vibrations of the transmission line in real conditions was analyzed. Such research was carried out by the authors of this paper taking into account the cross-section of the cable being in use on the transmission line. Analysis was performed for the modern ACSR high voltage transmission line with span of 213.0 m. The purpose of the investigation was to analyze the vibrations of the power transmission line in the natural environment and compare with the results obtained in the numerical simulations. Analysis was performed for natural and wind excited vibrations. The numerical model was made using the Spectral Element Method. In the spectral model, for various parameters of stiffness, damping and tension force, the system response was checked and compared with the results of the accelerations obtained in the situ measurements. A frequency response functions (FRF) were calculated. The credibility of the model was assessed through a validation process carried out by comparing graphical plots of FRF functions and numerical values expressing differences in acceleration amplitude (MSG), phase angle differences (PSG) and differences in acceleration and phase angle total (CSG) values. Particular attention was paid to the hysteretic damping analysis. Sensitivity of the wave number was performed for changing of the tension force and section area of the cable. The next aspect constituting the purpose of this paper was to present the wide possibilities of modelling and simulation of slender conductors using the Spectral Element Method. The obtained results show very good accuracy in the range of both experimental measurements as well as simulation analysis. The paper emphasizes the ease with which the sensitivity of the conductor and its response to changes in density of spectral mesh division, cable cross-section,tensile strength or material damping can be studied.     

Stability of a general adaptive immunity virus dynamics model with multistages of infected cells and two routes of infection

This paper studies an (n+4)-dimensional nonlinear virus dynamics model that characterizes the interactions of the viruses, susceptible host cells, n-stages of infected cells, B cells and cytotoxic T lymphocyte (CTL) cells. Both viral and cellular infections have been incorporated into the model. The infected-susceptible and virus-susceptible infection rates as well as the generation and removal rates of all compartments are described by general nonlinear functions. Five threshold parameters are computed, which insure the existence of the equilibria of the model under consideration. A set of conditions on the general functions has been established, which is sufficient to investigate the global dynamics of the model. The global asymptotic stability of all equilibria is proven by utilizing Lyapunov function and LaSalle's invariance principle. The theoretical results are illustrated by numerical simulations of the model with specific forms of the general functions.     

Mechanical and electrical response variation of the polyurethane–tin oxide–carbon nanotube composite microfiber depending on the chemical solution

Toward the goal of smart sensor systems for wearable electronics, polymer microfiber‐based free‐standing sensors benefit from excellent flexibility, decent ductility, and easy wearability in comparison with thin‐film‐based sensing devices. Herein, we report a hydrophobic and conducting single‐strand microfiber‐based liquid‐phase chemical sensor consisting of polyurethane (PU), tin oxide (SnO₂), and carbon nanotube (CNT) composites with applying a (1H,1H,2H,2H‐heptadecafluorodec‐1‐yl) phosphonic acid (HDF‐PA)‐based self‐assembled monolayer. The free‐standing HDF‐PA‐treated PU–SnO₂–CNT composite microfiber showing selective filtering properties with the repellency of water and the penetration of an organic solvent is electrically and mechanically characterized. Finally, the single‐strand HDF‐PA‐treated PU–SnO₂–CNT composite microfiber‐based chemical sensor, which shows excellent mechanical properties and aqueous stability, is demonstrated to detect the presence of a chemical in pure water or counterfeit gasoline in pure gasoline by observing mechanical changes, especially variations in the length and diameter of the fiber, and monitoring the electrical resistance change. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 495–502     

Temporal gradients in microfluidic systems to probe cellular dynamics: A review

Microfluidic devices have found a unique place in cellular studies due to the ease of fabrication, their ability to provide long-term culture, or the seamless integration of downstream measurements into the devices. The accurate and precise control of fluid flows also allows unique stimulant profiles to be applied to cells that have been difficult to perform with conventional devices. In this review, we describe and provide examples of microfluidic systems that have been used to generate temporal gradients of stimulants, such as waveforms or pulses, and how these profiles have been used to produce biological insights into mammalian cells that are not typically revealed under static concentration gradients. We also discuss the inherent analytical challenges associated with producing and maintaining temporal gradients in these devices.     

Photoelectric response of thiamonomethinecyanine J-aggregate nanoribbons deposited via dielectrophoresis technique

Different dyes can produce the two-dimensional self-assembled structures called J- and H-aggregates that make them attractive material for various nano-electronics applications. This paper shows that electrokinetic deposition technique of cyanine dye J-aggregates is appropriate for the photoelectric devices production. The influence of excitation in visible on conductivity is observed in J-aggregate channel structure deposited using dielectrophoresis technique. The effect was observed in self-assembled thiamonomethinecyanine nanostructures. Samples were analyzed using AFM and micro-Raman spectroscopy methods. Analysis shows that photoelectric response must be the result of conductive channel formation in the structure of J-aggregate between the electrodes. The observed increase in conductivity manifold exceeds the structure dark conductivity: maximal increase comprised 6.3 times.     

Superfast Responsive Ionic Hydrogels: Effect of the Monomer Concentration

A series of strong polyelectrolyte gels were prepared in aqueous solution, using the sodium salt of 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) as the monomer and N,N'‐methylene(bis)acrylamide (BAAm) as a crosslinker. The gels were both prepared below (?22°C) and above (25°C) the bulk freezing temperature of the water, producing cryogels and hydrogels, respectively. The crosslinker (BAAm) content was set at 17 mol%, while the initial monomer concentration C_o was varied over a wide range. It was found that, at ?22°C, a macroscopic network starts to form at an initial monomer concentration of as low as 0.1 w/v%. In contrast to the conventional hydrogels formed at 25°C, the cryogels have a discontinuous morphology consisting of polyhedral pores of sizes 10⁰–10² μm. The cryogels exhibit superfast swelling properties, as well as reversible swelling–deswelling cycles in water and acetone. An increase in the initial monomer concentration from 2.5 to 10% further increases the response rate of the cryogels due to the simultaneous increase of the porosity of the networks.     

pH-Responsive Phase Transition of Supramolecular Hydrogel Consisting of Glycosylated Amino Acetate and Carboxylic Acid Derivative

By addition of a carboxylated amino acetate (2) to a low-molecular-weight hydrogel (1) which has a unique thermally induced volume-phase transition character, a macroscopic pH-responsive feature is newly conferred on the supramolecular hydrogel. The direct observation of temperature-dependent behavior of the mixed hydrogel clearly showed that the thermally induced swelling-shrinkage type of the volume phase transition at pH 4 is shifted to the gel–sol transition at pH 7 by 10?mol% addition of 2 to the hydrogel 1. On the basis of the measurements by TEM, SEM, XRD and FT-IR, it is conceivable that incorporation of the anionic carboxylate of 2 slightly disturbs the packing of the hydrogen bond belt of the mixed hydrogel. Such a slight disturbance greatly leads to the sol–gel transition by elevating temperature, instead of the volume-phase transition. Introduction of dynamic characteristics to supramolecular systems in a macroscopic level may extend the potential of these materials in various fields.     

枝晶簇四方相钛酸钡的制备及其电场响应性能的研究

为了提高BaTiO3粒子在含水复合弹性体中的电场响应能力,本文采用简单的水热合成法,在不引入任何表面活性剂的情况下,仅通过对反应温度和溶液pH值的调控获得了新颖形貌的钛酸钡粒子。通过借助X射线衍射(XRD)、拉曼光谱(Raman)、扫描电子显微镜(SEM)及接触角(Contact Angle)测量等手段对粒子的微观结构和表面特性进行表征发现:该粒子为高纯四方相枝晶簇结构,具有良好的亲水性,而且在含水复合弹性体中对电场具有优良的响应能力。     

Efficient eco-friendly approach towards bimetallic nanoparticles synthesis and characterization using Exiguobacterium aestuarii by statistical optimization

ABSTRACT

Biogenic synthesis of bimetallic nanoparticles (gold – AuNp and selenium – SeNp) using inexpensive Tryptophan Enriched Banana Peel Media for the growth of marine isolate (Exiguobacterium aestuarii SBG4 MH185868). The response surface methodology is employed for optimizing production conditions. The surface plasmon resonance band showed λ_max at 540?nm (AuNp) and 284?nm (SeNp). FTIR and zeta potential analysis confirmed the stability, whereas XRD spectra revealed the nature of nanoparticles obtained at optimum conditions. SEM micrographs showed nanospheres of the following size: AuN, 30?±?5 nm and SeNp, 50?±?5 nm. Biocompatibility of Np evaluated by the hemolytic activity showed <20% hemolysis even at highest concentrations (100?µg/ml). AuNp showed the least cytotoxicity, whereas SeNp showed considerable cytotoxicity against the breast cancer cell lines MCF – 7 and MDA-MB-231. Hence, we utilized the environment-friendly growth media for the controlled synthesis of dual Np using single bacterial strain involving feasible steps in downstream processing.