Optimized structure and electrochemical properties of sulfonated carbon nanotubes/Co–Ni bimetallic layered hydroxide composites for high-performance supercapacitors

Technical development in electronic devices is frequently stifled by their insufficient capacity and cyclic stability of energy-storage devices. The nano-structured materials have sensational importance for providing novel and optimized combination to overcome exiting boundaries and provide efficient energy storage systems. Metal hydroxide materials with high capacity for pseudo-capacitance properties have grabbed special attention. Lately, the blend of nickel and cobalt hydroxides has been considered as a favorable class of metallic hydroxide materials owing to their comparatively high capacitance and exceptional redox reversibility. The sulfonated carbon nanotube fluid (SCNTF) was prepared by the ion exchange method to be utilized as the exceptional templates due to astonishing specific surface area, ensuring the maximum utilization of the active material. The CoNi-layered double hydroxides (LDHs)/SCNTF core-shell nanocomposite was prepared by the simple solvothermal method. Structural analysis showed that the composite material had the high conductance of carbon materials, the pseudo-capacitance characteristics of metal hydroxides, and porous structure, which facilitates the ion shuttle when the electrolyte reacts with the active material. Electrochemical analysis results showed that CoNi-LDHs/SCNTF had excellent rate performance, reversible charge-discharge properties and cycle stability. It exhibited an extreme specific capacity of 1190.5 F g^?1 at a current density of 1 A g^?1; whereas specific capacity remained 953.7 F g^?1 at the current density was 10 A g^?1. In addition, the capacity retention rate after 5000 charge-discharge cycles at a current density of 20 A g^?1 was 81.0%. The results indicated that the CoNi-LDHs/SCNTF core-shell nanocomposite material is cost efficient and an effective substitute in energy storage applications.     

Green synthesis of zinc oxide nanoparticles using Amygdalus scoparia Spach stem bark extract and their applications as an alternative antimicrobial,anticancer, and anti-diabetic agent

For the first time in this study, Zinc oxide nanoparticles were biosynthesized by the eco-friendly and cost-effective procedure using Amygdalus scoparia stem bark extract then used as antibacterial, antifungal, anticancer, and anti-diabetic agents. The characterization techniques confirmed the biosynthesis, crystalline nature, structure, size, elemental composition of ZnO NPs and bioactive compounds that exist in A. scoparia extract accounting for Zn²⁺ ion reduction, capping and stabilization of ZnO NPs. The ZnO NPs displayed remarkable inhibitory activity against E. coli, E. aerigenes, S. aureus, P. oryzae, F. thapsinum, and F. semitectum compared to antibiotic standards. The ZnO NPs showed significant inhibitory effects on cancer cell lines, while it had no toxic effect on Vero normal cell line. The ZnO NPs (30 mg/kg)-treated diabetic rats showed significantly higher levels of insulin and lower AST, ALT and blood glucose compared with the STZ induced diabetic group and other treated groups (P < 0.05). The ZnO NPs- and extract-treated rats showed significantly higher levels of IR, GluT2, and GCK expression and lower TNFα expression compared with the STZ induced diabetic rats. Our findings showed that ZnO NPs represented an outstanding performance for biological applications.     

An experimental study of forced convective heat transfer for fully developed Al 2 O 3 –water nanofluid in an annulus tube

Nanofluids have been known as practical materials to ameliorate heat transfer within diverse industrial systems. The current work presents an empirical study on forced convection effects of Al₂O₃–water nanofluid within an annulus tube. A laminar flow regime has been considered to perform the experiment in high Reynolds number range using several concentrations of nanofluid. Also, the boundary conditions include a constant uniform heat flux applied on the outer shell and an adiabatic condition to the inner tube. Nanofluid particle is visualized with transmission electron microscopy to figure out the nanofluid particles. Additionally, the pressure drop is obtained by measuring the inlet and outlet pressure with respect to the ambient condition. The experimental results showed that adding nanoparticles to the base fluid will increase the heat transfer coefficient (HTC) and average Nusselt number. In addition, by increasing viscosity effects at maximum Reynolds number of 1140 and increasing nanofluid concentration from 1% to 4% (maximum performance at 4%), HTC increases by 18%.     

Ferromagnetic nano model study for the peristaltic flow in a plumb duct with permeable walls

Microsystem Technologies - The purpose of the present enquiry is to analyse the mechanics of an incompressible fluid, with water as base fluid, through a radially symmetric plumb duct with...     

Trans-differentiation of human adipose-derived mesenchymal stem cells into cardiomyocyte-like cells on decellularized bovine myocardial extracellular matrix-based films

In this study, we aimed at fabricating decellularized bovine myocardial extracellular matrix-based films (dMEbF) for cardiac tissue engineering (CTE). The decellularization process was carried out utilizing four consecutive stages including hypotonic treatment, detergent treatment, enzymatic digestion and decontamination, respectively. In order to fabricate the dMEbF, dBM were digested with pepsin and gelation process was conducted. dMEbF were then crosslinked with N-hydroxysuccinimide/1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide (NHS/EDC) to increase their durability. Nuclear contents of native BM and decellularized BM (dBM) tissues were determined with DNA content analysis and agarose-gel electrophoresis. Cell viability on dMEbF for 3rd, 7th, and 14th days was assessed by MTT assay. Cell attachment on dMEbF was also studied by scanning electron microscopy. Trans-differentiation capacity of human adipose-derived mesenchymal stem cells (hAMSCs) into cardiomyocyte-like cells on dMEbF were also evaluated by histochemical and immunohistochemical analyses. DNA contents for native and dBM were, respectively, found as 886.11?±?164.85 and 47.66?±?0.09?ng/mg dry weight, indicating a successful decellularization process. The results of glycosaminoglycan and hydroxyproline assay, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), performed in order to characterize the extracellular matrix (ECM) composition of native and dBM tissue, showed that the BM matrix was not damaged during the proposed method. Lastly, regarding the histological study, dMEbF not only mimics native ECM, but also induces the stem cells into cardiomyocyte-like cells phenotype which brings it the potential of use in CTE.     

Thermodynamic performance analysis of three solid oxide fuel cell and gas microturbine hybrid systems for application in auxiliary power units

In this study, three different configurations of a solid oxide fuel cell and gas microturbine hybrid system are evaluated for application in auxiliary power units. The first configuration is a common hybrid system in auxiliary power units, utilizing a fuel cell stack in the structure of the gas turbine cycle. The other configurations use two series and parallel fuel cell stacks in the structure of the gas turbine cycle. The main purpose of this research is thermodynamic analysis, evaluation of the performance of the proposed hybrid systems in similar conditions, and selection of an appropriate system in terms of efficiency, power generation, and entropy generation rate. In this study, the utilized fuel cells were subjected to electrochemical, thermodynamic, and thermal analyses and their working temperatures were calculated under various working conditions. Results indicate that the hybrid system with two series stacks had maximum power generation and efficiency compared with the other two cases. Moreover, the simple hybrid system and the system with two parallel stacks had relatively equal pure power generation and efficiency. According to the investigations, hybrid system with two series fuel cell stacks, which had 3424 and 1712 cells, respectively, can achieve the electrical efficiency of over 48%. A hybrid system with two parallel fuel cell stacks, in which each stack had 2568 cells, had the electrical efficiency of 46.3%. Findings suggested that maximum electrical efficiency occurred between the pressure ratios of 5–6 in the proposed hybrid systems.     

Effect of sand and clay fouling on the shear strength of railway ballast for different ballast gradations

Ballast contamination by fine materials such as sand and clay in railway track at arid regions is an important issue that causes track instability problems and settlement due to reduction of shear strength of ballast. In this paper, the results of direct shear box test conducted on clean ballast, sand-fouled ballast and clay-fouled ballast for different ballast gradations are reported and discussed. For this purpose, three different fouling amounts according to fouling index are added to clean ballast. Test results show that by increasing the fouling percentage, the ballast shear strength always decreases both for sand and clay fouled ballast. However, the amount of shear strength reduction is low at high normal stresses. Clay contamination has more adverse effect on the shear strength of ballast compared with sand contamination. Also, the results of tests for evaluation of gradation effect on shear strength of fouled ballast which are conducted on various gradations according to American Railway Engineering and Maintenance-of-Way Association, show that the maximum particle size as well as uniformity coefficient affect the shear strength of ballast. Also, an empirical equation is presented to observe the effect of ballast gradation on reduction of shear strength with regard to amount of fouling material and normal stress.     

Pressure Management in Water Distribution Systems Using a Self-Tuning Controller to Distribute the Available Potable Water with Equality

The rapid population growth of cities in developing countries (DC) make difficult to distribute the available potable water (PW) with equality. The distribution problem arises from an insufficient amount of PW and because cities water distribution systems (WDS) are not efficient. The novelty of this paper is a self-tuning controller (STC) proposed to manage, along the day, the pressure of water through the nodes of a WDS. It means, pressure management (PM) is proposed to control water levels (WLs) in householders tanks (HTs). The objective is to satisfy with equality the PW demand at different zones of a city forcing the flow of water by managing the pressure. The proposed STC performance is tested on the digital simulator developed to characterize the hydraulic operation of a WDS. The dynamic behaviour of the WDS is determined by the variation of the WL in the tanks of the WDS when water is supplied or extracted from them. The WDS of Mexico City is analysed and the proposed STC is applied to a simplified WDS. The results allow to conclude that the proposed STC could become a supporting tool for the decision making of WDS operators.     

Imaging of two-dimensional unsaturated moisture flows in uncracked and cracked cement-based materials using electrical capacitance tomography

The development of visualizing tools to monitor unsaturated moisture flow in cement-based materials is of great importance, as most degradation processes in cement-based materials are connected to and take place in the presence moisture. This paper investigates the ability of electrical capacitance tomography (ECT) to image two-dimensional (2D) unsaturated moisture flow in cement-based materials. In ECT, the electrical permittivity distribution within an object is reconstructed based on measured capacitances between electrodes attached on the object’s surface. In a series of experiments, mortar specimens with and without discrete cracks were imaged with ECT during a 2D moisture ingress. The results show that ECT is able to monitor the evolution of the moisture flow, and to approximate the shape and position of the moisture front. These findings indicate that ECT is a viable method for monitoring and visualizing 2D unsaturated moisture flow in cement-based materials in the presence and absence of discrete cracks.