Coil‐Type Asymmetric Supercapacitor Electrical Cables

Cable‐shaped supercapacitors (SCs) have recently aroused significant attention due to their attractive properties such as small size, lightweight, and bendability. Current cable‐shaped SCs have symmetric device configuration. However, if an asymmetric design is used in cable‐shaped supercapacitors, they would become more attractive due to broader cell operation voltages, which results in higher energy densities. Here, a novel coil‐type asymmetric supercapacitor electrical cable (CASEC) is reported with enhanced cell operation voltage and extraordinary mechanical‐electrochemical stability. The CASECs show excellent charge–discharge profiles, extraordinary rate capability (95.4%), high energy density (0.85 mWh cm⁻³), remarkable flexibility and bendability, and superior bending cycle stability (≈93.0% after 4000 cycles at different bending states). In addition, the CASECs not only exhibit the capability to store energy but also to transmit electricity simultaneously and independently. The integrated electrical conduction and storage capability of CASECS offer many potential applications in solar energy storage and electronic gadgets.     

Recent Advances in Boron Nitride Based Hybrid Polymer Nanocomposites

Boron nitride (BN) is an eminent inorganic compound having many interesting characteristics such as improved oxidation resistance, mechanical strength, good thermal conductivity (TC), higher bandgap, high chemical stability, thermal stability, high hydrophobicity, and electrical insulation. The use of BN as a filler in polymers is a well-established strategy to tailor the properties of polymer composites. Recent studies depict an interesting urge to reap the synergistic effect of various nanofillers with BN in the form of hybrids. Hence the consolidation of the works on BN based hybrid fillers would definitely attract researchers so that these new filler systems could be transformed into useful polymer nanocomposites in future. This review article focuses on the synthesis and characterization of various boron nitride based hybrids in detail. Moreover, the review also throws light on different BN hybrid reinforced polymer nanocomposites (PNCs) and their thermal, electrical, electronic as well as biomedical applications in a detailed manner. Thus the review anticipates serving as a tool toward understanding the recent trends in the field of boron nitride hybrid based ternary polymer composites.     

Microstructural design of neodymium-doped lanthanum–magnesium hexaaluminate synthesized by aqueous sol–gel process

Aqueous sol–gel processing was used to synthesize neodymium-doped magnesium hexaaluminate (La_1?x Nd _x MgAl₁₁O₁₉; x = 0, 0.3, 0.4, 0.5) ceramic powder and subsequently calcined at 1450 and 1600 °C for 2 h. Randomly grown platelets of lanthanum–magnesium hexaaluminate formed a porous interlocking structure. Presence of various percentages of neodymium oxide significantly modifies the porous interlocking microstructure into self-reinforced, card-house-like microstructure. Platelets of rare earth-rich magnesium hexaaluminate were grown preferentially more than the stoichiometric rare earth magnesium hexaaluminate at elevated temperature greater than 1450 °C. Rare earth-rich magnesium hexaaluminate platelets form the skeleton of a card-house structure and the tiny platelets of stoichiometric rare earth magnesium hexaaluminate fill the house. The specific heat capacities, micro-hardness, and fracture toughness were studied in details.     

Development of functionalized chitosan-coated carboxylated mesoporous silica: a dual drug carrier

The principle aim of the present study is to synthesis a novel mesoporous silica-based dual drug delivery system (DDDS) with unique features for the delivery of amoxicillin (antibiotic) and thiamine hydrochloride (vitamin). The DDDS was characterized by Fourier transform infrared, X ray diffraction, differential scanning calorimetry, scanning electron microscopy and atomic force micrographs analyses. The stimuli response behaviour of the drug carrier was studied by conducting swelling experiments as a function of pH and time. Drug release studies were carried out by mimicking gastric and intestinal conditions and found that the release of both drugs attained its maximum in the intestinal condition. The in vitro release data were analysed using Peppa’s potential equation in order to predict the release mechanism. The release of antibiotic follows non-Fickian mechanism whereas that of vitamin was diffusion controlled. An in vitro cytotoxicity analysis was carried out on L929 cells and the results showed that the synthesized DDDS is safe. DPPH assay and antibacterial activity were also analysed. From the investigation, it is evident that the prepared DDDS has potential application as dual drug carrier.     

Low resistive silicon substrate as an etch-stop layer for drilling thick SiO2 by spark assisted chemical engraving (SACE)

Controlling precisely the depth in glass micro-drilling by spark assisted chemical engraving (SACE) remains challenging, particularly for low depths. The possibility of using an electrically conductive material as an etch-stop layer for SACE gravity-feed drilling is investigated in this paper. Micromachining with constant DC and pulsed DC of 30–35 μm thick SiO₂ deposited on low resistive silicon substrate demonstrated the etch-stop function of the conductive silicon. Measurements of etch rates and hole profiles along with scanning electron microscope imaging revealed the mechanism underlying the etch-stop process. Low resistive silicon is demonstrated to be a good etch-stop layer for SACE gravity-feed drilling. Demonstration of machining of SiO₂ layer on silicon as a substrate and an etch-stop layer opens up new possibilities to adapt SACE for developing devices on silicon platform.     

Field Assessment of the Performance of a Ballasted Rail Track with and without Geosynthetics

Understanding the complex mechanisms of stress transfer and strain accumulation in layers of track substructure under repeated wheel loading is essential to predict the desirable track maintenance cycle as well as the design of the new track. Various finite element and analytical techniques have been developed in the past to understand the behavior of composite track layers subjected to repeated wheel loads. The mechanical behavior of ballast is influenced by several factors, including the track confining pressure, type of aggregates, and the number of loading cycles. A field trial was conducted on an instrumented track at Bulli, New South Wales, Australia, with the specific aims of studying the benefits of a geocomposite installed at the ballast-capping interface, and to evaluate the performance of moderately graded recycled ballast in comparison to traditionally very uniform fresh ballast. It was found that recycled ballast can be effectively reused if reinforced with a geocomposite. It was also found that geocomposite can effectively reduce vertical and lateral strains of the ballast with obvious implications for improved track stability and reduced maintenance costs.     

Multiwall carbon nanotubes grown by thermocatalytic carbonization of polyacrylonitrile

A method is reported for the growth of multiwall carbon nanotubes (MWCNTs) using polyacrylonitrile as a solid carbon source and nanosized SiO₂ particles as catalyst. The nanotubes were grown either on a Si substrate or as a freestanding film at temperatures as low as 800 °C. The smallest measured inner diameter of the resultant MWCNTs is about 0.6 nm and therefore this method provides a new direction to prepare MWCNTs with very small inner diameter from solid carbon source.     

Experimental analysis of a two‐axis tracking system for solar parabolic dish collector

In this paper, an attempt has been made to develop a two‐axis tracking system for solar parabolic dish concentrator and experimentally evaluated the performance of the tracking system. In this proposed design, the sensor design uses the illumination produced by the convex lens on the apex of a pyramid to align the dish in‐line with the sun. The change in incident angle of the solar rays on the lens surface shifts the area of illumination from the apex of the pyramid towards its faces. Photodiodes placed on the faces of the pyramid are used as the sensitive elements to detect the movement of the sun. The sensor output is fed to a microcontroller‐based system to drive the stepper motor on the basis of the programmed algorithm such that it receives normal incidence of sunlight on the sensor. To evaluate the performance of the proposed system, a conventional available 1‐W photovoltaic (PV) panel is placed at the focal point to measure the short circuit current and open circuit voltage. With respect to the conventional solar PV panel, it is observed that the positioning accuracy of the proposed tracking system enhances the short circuit current of 0.11 A by 86%. Thus, the proposed tracking system can be used in a stand‐alone parabolic dish with concentrating PV module as the focal point for further studies.