PVA/starch/propolis/anthocyanins rosemary extract composite films as active and intelligent food packaging materials

Active and intelligent food packaging films has taken more importance over conventional packaging. The aim of this study was to develop active and intelligent food packaging films based on bio-degradable polymers like polyvinyl alcohol and starch, incorporated with natural additives, that is, propolis extract (PE) and Anthocyanin. Boric acid was used as a cross-linker. The results proved the compatibility of films mixture. The mechanical strength was also measured and highest value was achieved 6.1 MPa for films containing 20% PE. Moreover, the maximum zone of inhabitation, that is, 21 and 15 mm, was also achieved at same composition against Escherichia coli and methicillin-resistant Staphylococcus aureus, respectively. Furthermore, all films had shown great color response against different pH ranging from 2 to 14. Finally, food spoilage test was performed using pasteurized milk. Films responded visibly by changing color and protected milk from spoilage. Hence, formulated bio-degradable active and intelligent films can be used as food packaging material.     

NiFe2O4/SiO2 nanostructures as a potential electrode material for high rated supercapacitors

Engineered materials are crucial for the higher efficiency of supercapacitors. Current work presents roughly shaped spherical NiFe₂O₄ nanoparticles dispersed in the SiO₂ matrix NiFe₂O₄/SiO₂ as a newfangled electrode material for supercapacitors with remarkable performance. Designing the NiFe₂O₄/SiO₂ nanostructure with a sol-gel method followed by the Stober method to grow silica has instigated NiFe₂O₄/SiO₂ as dynamic material with higher electrochemical activity. Physicochemical aspects of NiFe₂O₄/SiO₂ nanostructures are evaluated using Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analysis. The electrochemical activity is evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) representing the comparable efficiency and reversibility of the electrode materials. The prepared electrode shows a capacitance of 925 F/g (154.1 mAh/g or 555 C/g) at 1 A/g, with 95.5% capacitance retention after 5000 cycles at 20 mA/cm². The improved electrochemical performance of the NiFe₂O₄/SiO₂ electrode can be subjected to prompt diffusion process provided by NiFe₂O₄/SiO₂ and enhanced redox reactions owing to the high surface area. The mentioned features decrease the total impedance of the electrodes as suggested by electrochemical impedance spectroscopy (EIS).     

Synthesis of highly pure single crystalline SnSe nanostructures by thermal evaporation and condensation route

Here we report the synthesis of highly pure single crystalline tin selenide (SnSe) nanospheres by pretreatment of precursors with aqueous ammonia. In this work we have demonstrated that aqueous ammonia not only controls the preferred growth orientation but also controls the morphology of SnSe. Chemical vapor deposition technique was used for the growth of SnSe nanostructures. The optical properties were studied using UV–vis–NIR spectroscopy and Photoluminescence (PL) spectrum.     

Structure-Based Low Complexity MMSE Channel Estimator for OFDM Wireless Systems

Wireless communication systems utilizing orthogonal frequency division multiplexing (OFDM) transmissions are capable of delivering high data rates over multipath frequency selective channels. This paper deals with joint estimation/interpolation of wireless channel using pilot symbols transmitted concurrently with the data. We propose a low complexity, spectrally efficient minimum mean square error channel estimator which exploits the correlation structure of channel frequency response for reducing the complexity. Specifically, it is shown that if pilots are inserted appropriately across OFDM subcarriers, the proposed algorithm requires no matrix inversion, thereby significantly relieving the computational burden without deteriorating the performance. Moreover, the knowledge of channel correlation is also not required for the proposed estimator. Simulation results validate that the proposed technique outperforms existing low-complexity variants in terms of mean square error and computational complexity.

     

Synthesis and characterization of poly 2-N-acrylamido-2-methyl−1-propane sulfonic acid functionalized graphene oxide embedded electrolyte membrane using DOE for PEMFC

A novel proton exchange membrane consisting of 2-N-acrylamido-2-methyl−1-propane sulfonic acid modified graphene oxide nanocomposite (PAMPS-mGO), carboxylated poly(vinyl chloride) (CPVC), and poly 2-N-acrylamido-2-methyl−1-propane sulfonic acid (PAMPS) has been successfully prepared by simple and scalable polymer blending methodology. Different compositions of PEM in terms of its constituting precursors such as PAMPS-mGO, CPVC, and PAMPS were optimized by Placket Burman Design and their ion exchange capacity (IEC), oxidative stability, water uptake percentage, mechanical stability, and proton conductivity were evaluated. The amounts of significant precursors were further optimized by Central Composite Design. The membrane with excellent performance in PEMFC was obtained when appropriate proportions of CPVC (10%), PAMPS (20%), and PAMPS-mGO (20%) were blended. Among all membrane with mentioned composition exhibited IEC 1.3 mmol/g, oxidative stability 97.2%, WU 40.8%, proton conductivity 151 S/cm, water content 17.43, current density 1537 mA/cm² at 120°C, power density 566.5 mW/cm² at 120°C, Young modulus 797 MPa, tensile strength 16.8 MPa, and elongation at break % of 2.7 MPa. These results are in good comparison with PEM based on Nafion. Thus, the CPVC, PAMPS, and PAMPS-mGO-based composite PEM is a good candidate for PEMFC at elevated temperature under anhydrous conditions.     

Synthesis,characterization, enhanced dielectric and antimicrobial properties of WxCu1−xO nanostructures

Herein, we report the chemical synthesis of W_x Cu_1?xO nanostructures with varying concentration of dopant (x = 0.00, 0.01, 0.03 and 0.05). The as-obtained doped CuO nanostructures have been investigated to evaluate their physio-chemical properties like crystallinity, morphology, optical features and infrared active modes. The dielectric study shows that doping induces a significant increase in real permittivity. In addition, the doped nanostructures also show potential towards inhibition of pathogenic microbes. The antimicrobial activity of prepared nanostructures determined against four different bacterial strains shows that W doped CuO nanostructures possess a strong antimicrobial activity against S. aureus, and K. pneumoniae and an intermediate activity against E. coli and C. albicans. These finding recognize the use of W doped CuO nanostructures in permittivity materials and bacterial disinfection nanomaterials.     

Enhanced mechanical properties of wood ash and fly ash as supplementary cementitious materials

The incorporation of fly ash (FA) and wood ash (WA) in concrete as supplementary cementitious materials (SCM) was studied. The chemical composition of ordinary Portland cement, FA and WA was determined according to ASTM C-114. SEM and optical microscopy were used for the analysis of concrete. Setting time, compressive strength, water absorption and acid resistance of the concrete with different percentages of SCM ranging from 0 to 60% were evaluated. The results obtained showed that setting time and rate of water absorption increased with the increase in percentage of SCM. After 7 and 28 days, the compressive strength of concrete with 20% FA as SCM was higher than that with substitution with 20% WA. Resistance of concrete against sulphate attack increased with an increase in the percentage of FA. It was found that incorporating more than 20% WA resulted in a decrease in sulphate attack resistance.     

Synthesis,evolution and hydrogen storage properties of ZnV2O4 glomerulus nano/microspheres: A prospective material for energy storage

We present first study on ZnV₂O₄ glomerulus nano/microspheres synthesize by template free route to expose its hydrogen storage potential. Besides this the evolution of nano/microspheres has been investigated in detail. To reveal possible growth mechanism of these spheres, time-dependent experiments are performed. Reitveld analysis is taken into account for calculation of lattice parameters, crystallite size and strain. From our results, a correlation between lattice parameters and crystallite size is observed. The strain decreases with the increase in reaction time. Hydrogen storage measurement reveals potential of ZnV₂O₄ nanospheres as a prospective material for energy storage applications. These studies can open new avenue of research for hydrogen storage in spinel oxide materials.