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A high electrochemical performance and cost effective solid state NiCo 2 O 4 material was synthesized by hydrothermal method. The performance of the supercapacitor material was investigated by incorporating the zinc and manganese in the crystal structure of NiCo 2 O 4 . The structure and morphology were confirmed by X-ray diffraction (XRD) pattern and Field Emission Scanning Electron Microscope (FE-SEM), and High Resolution Transmission Electron Microscope (HR-TEM). The optical absorption spectra of the pure and co-doped NiCo 2 O 4 were investigated by UV-Vis analysis and the bandgap energy was found to be 4.38 and 2.98 eV respectively. Photoluminescence spectra (PL) reveal the blue and green emission peaks were found at 364, 376 and 488 nm respectively. The pore size and surface area of Mn, Zn co-doped NiCo 2 O 4 was evaluated by Brunauer -Emmett -Teller analysis (BET). The cyclic voltammetry (CV) reveals the faradaic reaction of the pure and co-doped NiCo 2 O 4 with excellent reversibility at higher scan rates. The maximum specific capacitance for pure and co-doped NiCo 2 O 4 nanoparticles (NPs) was achieved as 158.6 and 513.17 Fg À 1 respectively. Further, the electrochemical impedance spectroscopy (EIS) and galvanostatic charge discharge (GCD) were performed to identify the resistance and rate capability of the electrode materials. The cyclic stability of pure and Zn, Mn codoped NiCo 2 O 4 was found to be 90.8 % and 95.07 % respectively for 3000 Cycles. The Zn, Mn co-doped NiCo 2 O 4 can be used as an excellent electrode for supercapacitor applications.

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This study has been taken to investigate the exact rebound-strength relationship of different grades of concrete, as the curves generated for traditional hammers are outdated. Using the material available in the Nagpur region, cube specimens were cast and tested as per IS:516-1959 [1]. Several sets were cast with varying cement contents, decided by mix design, to give a strength range of 10 to 50 Mpa. However, for this study, the Target Mean Strength Standard Deviation factor is not considered. We tested these sets for compressive strengths; each specimen was checked for rebound value for compressive Strength, each specimen was checked for rebound value on four faces. Thus, for each specimen, data for rebound value and Compressive Strength is available. Using this data, a curve for Compressive Strength and rebound value was plotted. The curve generated indicated that the strengths obtained for the same rebound value are higher than that using the traditional curve. There is an increase of about 47% up to a strength of 21 Mpa. From 21 to 38 Mpa, this increase is almost constant to about 30%. From this point forward, the rate of increased Strength reduces by 25% and 14% at 40 Mpa and 45 Mpa, respectively.