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Energy crisis and environmental pollution have been one of the major global issues. In this regard, the search for new energy storage materials is cheap, flexible and high-performance supercapacitors electrode which has become intensive. Also, reducing the amount of organic dyes polluting in water is a great significance. Herein, one-step electropolymerization of methylene blue on carbon fiber and the resulting films were applied to the supercapacitor. The high performance is associated to the outstanding conductivity, electrochemical stability and superior mechanical flexibility of carbon fiber. A new flexible electrode for supercapacitors was successfully fabricated by demonstrating with a good electrochemical performance and a promising alternative to reduce the water pollution.

Supercapacitors are considered as one of the most efficient and reliable approaches to fulfill the specifications of the energy storage devices, owing to high-efficiency storage of energy, which makes supercapacitive electrode materials provoke large curiosity. In this work, we report the electropolymerization of poly(p-phenylenediamine) (PpPD) films on lightweight and inexpensive flexible carbon fiber fabrics by potentiostatic technique. The ladder structure of the electrochemically prepared PpPD was examined by Fourier transform infrared spectroscopy (FTIR). The surface characteristics and elemental composition studies were performed through field-emission scanning electron microscope (FESEM) and energy-dispersive X-ray spectroscopy (EDS), which confirmed the polymerization on the carbon fabrics. The electrochemical behavior of the fabricated supercapacitors was investigated by electrochemical analysis including cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The electrodes presented a good capacitive retention in a sweep rate range between 5 and 100 mV s−1 using cyclic voltammetry. The coated electrode exhibited good electrochemical property with a high specific capacitance of 80 F g−1 at the current density of 1 A g−1. The high electrochemical performance is associated to the outstanding conductivity, high electrochemical stability, and superior flexibility of the carbon fiber fabrics. The accomplishment of such superior performance, lightweight, and mechanically flexible supercapacitor can stimulate the use in energy storage applications and wearable electronics.

This paper reports the fabrication of an ultra-high energy and power density asymmetric supercapacitor (ASC) containing a novel porous carbon nanofiber derived from hypercross-linked polymers (HCP-CNF) and two-dimensional copper cobalt oxide nanosheets (CCO-NS) as the negative and positive electrodes, respectively. The micropore-enriched HCP-CNF is obtained from a facile Friedel-Crafts reaction with naphthalene and α, α′-dichloro-p-xylene as the starting material. The CCO-NS have been prepared by a simple and inexpensive hydrothermal synthesis using polyvinylpyrrolidone (PVP) as a shape controlling agent. The fabricated CCO-NS//HCP-CNF ASC device exhibit a high specific capacitance, 244 F g−1 at a current density of 1 A g−1, owing to the unique porous architecture of CCO-NS and the interconnected microporous carbon skeleton with a high surface area of HCP-CNF. Furthermore, the assembled ASC device show an ultra-high energy density of 25.1 Wh kg−1 at a power density of 400 W kg−1 with maximum operating voltage of 1.60 V. The electrode shows good capacitance retention (91.1%) after 5000 cycles in a 3 M aqueous KOH solution. In addition, two ASC devices are connected in series powered a 5 mm diameter LED indicator for approximately 30 min, highlighting its efficient power supply.

Sonoluminescence (SL) is a physicochemical phenomenon that is observed when a single or multiple air bubbles, excited by an acoustic field in water, collapse and emit light. Until nowadays, it is still an outstanding phenomenon in which acoustic energy is (partially) transformed into light. Along the years, some models have been proposed to explain sonoluminescence and a lot of experimental setups have been built in an attempt to reproduce and study it. Since the flash of light is forced to occur inside a resonant cavity (i.e., a glass flask filled with water) by using external circuitry, many efforts have been made to study the relationship between the phenomenon and the electrical and mechanical quantities involved in the experimental apparatus. Following this field of study, this paper proposes an electronic instrumentation system based on a FPGA device for performing automatic monitoring of the input signal applied to the resonator as well as the output response signal produced by it. The objective of using the automated setup is to collect data for characterizing the resonator frequency response in order to identify its input/output behavior. The key idea is to find out whether there is a linear circuit which might have analogous input/output characteristics that may be used to simulate the phenomenon in future studies.

Nitrogen rich porous carbon balls are derived from hypercross-linked polymers (HCPs) of anthracene and subsequent carbonization with urea. The obtained materials exhibit combination of abundant microporous and minimal mesoporous property with large surface area (623.27 to 928.44 m2 g − 1). The influence of annealing temperature in nitrogen doped porous HCPs was examined the capacitive performance of the prepared electrode materials using electrochemical techniques. A symmetric device was assembled, and it shows a high specific capacitance of 206.4 F g − 1 at 0.2 A g − 1 with excellent rate capability. Also, the material exhibits excellent durability only 3.5% loss was observed after 5000 cycles (capacitance retention of 96.5%). These outcomes justify that nitrogen anchored porous carbon balls are excellent materials for high-performance symmetric supercapacitors.

Dicalcium phosphate dihydrate (DCPD) brushite coating with flake like crystal structure for the protection of AZX310 and AM50 magnesium (Mg) alloys was prepared through chemical deposition treatment. Chemical deposition treatment was employed using Ca(NO3)2·4H2O and KH2PO4 along with subsequent heat treatment. The morphological results revealed that the brushite coating with dense and uniform structures was successfully deposited on the surface of AZX310 and AM50 alloys. The X-ray diffraction (XRD) patterns and Attenuated total reflectance infrared (ATR-IR) spectrum also revealed the confirmation of DCPD layer formation. Hydrophilic nature of the DCPD coatings was confirmed by Contact angle (CA) measurements. Moreover, electrochemical immersion and in vitro studies were evaluated to measure the corrosion performance and biocompatibility performance. The deposition of DCPD coating for HTI AM50 enables a tenfold increase in the corrosion resistance compared with AZX310. Hence the ability to offer such significant improvement in corrosion resistance for HTI AM50 was coupled with more bioactive nature of the DCPD coating is a viable approach for the development of Mg-based degradable implant materials.

This paper describes a six degrees of freedom dynamic model for the development of ballast control systems for semi-submersible platforms. The dynamic model includes the effects of the ballast tanks such as weights, moments and inertias. The parameters of the dynamic model are computed from geometric data and from experimental results obtained with a small semi-submersible platform. The hull of the platform is represented by a mesh of tetrahedrons to allow the computation of the displacement and the center of buoyancy, which are important for the evaluation of the stability of the platform.