Biofabrication of silver nanoparticles using bacteria from mangrove swamp

The last decade has observed a rapid advancement in utilising biological system towards bioremediation of metal ions in the form of respective metal nanostructures or microstructures. The process may also be adopted for respective metal nanoparticle biofabrication. Among different biological methods, bacteria‐mediated method is gaining great attention for nanoparticle fabrication due to their eco‐friendly and cost‐effective process. In the present study, silver nanoparticle (AgNP) was synthesised via continuous biofabrication using Aeromonas veronii, isolated from swamp wetland of Sunderban, West Bengal, India. The biofabricated AgNP was further purified to remove non‐conjugated biomolecules using size exclusion chromatography, and the purified AgNPs were characterised using UV–visible spectroscopy, X‐ray diffraction, field emission scanning electron microscopy and transmission electron microscopy (TEM). Additionally, the presence of proteins as capping and stabilising agents was confirmed by the amide‐I and amide‐II peaks in the spectra obtained using attenuated total reflection Fourier transform infrared spectroscopy. The size of biofabricated AgNP was 10–20 nm, as observed using TEM. Additionally, biofabricated AgNP shows significant antibacterial potential against E. coli and S. aureus. Hence, biofabricated AgNP using Aeromonas veronii, which found resistant to a significant concentration of Ag ion, showed enhanced antimicrobial activity compared to commercially available AgNP.Inspec keywords: silver, nanoparticles, microorganisms, nanofabrication, purification, chromatography, ultraviolet spectra, visible spectra, X‐ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, proteins, molecular biophysics, biochemistry, molecular configurations, attenuated total reflection, Fourier transform infrared spectra, particle size, antibacterial activity, biomedical materials, nanomedicineOther keywords: capping agents, stabilising agents, amide‐I peaks, amide‐II peaks, attenuated total reflection Fourier transform infrared spectroscopy, antibacterial potential, E. coli, S. aureus, Aeromonas veronii, antimicrobial activity, size 10 nm to 20 nm, Ag, proteins, TEM, transmission electron microscopy, field emission scanning electron microscopy, X‐ray diffraction, UV‐visible spectroscopy, size exclusion chromatography, nonconjugated biomolecules, purification, swamp wetland, Aeromonas veronii, cost‐effective process, eco‐friendly, bacteria‐mediated method, biological methods, metal nanoparticle biofabrication, microstructures, metal nanostructures, metal ions, bioremediation, biological system, mangrove swamp, bacteria, silver nanoparticles     

A dual feed PIN diode based switchable multiband planar meandered antenna for intelligent transportation system application

This article presents a dual feed switchable coplanar linearly polarized multiband meandered microstrip patch antenna. The antenna provides multiband functionalities with switching allowable at one of the nine adjacent frequencies. The proposed antenna, loaded with two symmetric PIN diodes, comprises dual‐patch configuration and excited by coplanar microstrip feeds, it operates within 1 to 15 GHz frequency bands. The induced current of the antenna can be changed by switching the diodes, resulting in different operating frequency bands. The antenna has a nearly broadside radiation pattern and the impedance bandwidth is obtained up to 47% having a center frequency of 2.4 GHz for band range of 1 to 15 GHz. The measured gain of the antenna for 1.57, 2.4, 4.5, 4.71, 5.9, 6.53, 7.59, 10.8, and 11.87 GHz are 5, 5, 7, 6, 6.1, 4.4, 3.8, 3.5, and 1.87 dBi, respectively. The antenna has advantages of the simple biasing network, easy fabrication, and adjustment. It is suitable for many modern wireless communication systems like intelligent transportation system. This antenna is also useful in direct broadcast satellite applications.     

Thermal insulation behaviour of Ethylene propylene diene monomer rubber/kevlar fiber based hybrid composites containing Nanosilica for solid rocket motor insulation

The current research discusses the properties of an elastomeric heat-shielding material, based on nano-silica (NS) filled ethylene propylene diene monomer (EPDM) rubber/Kevlar fiber (KF) hybrid composites. The developed elastomeric insulating material consists of an aromatic polyamide fiber (KF) and silica nanoparticles. An in-depth analysis of mechanical properties, density, coefficient of thermal expansion, thermal conductivity, thermogravimetric analysis, and heat release rate of the insulating materials -was performed. TEM micrograph represents an excellent distribution of nanoparticles in the EPDM matrix. The improvement in the mechanical and the flame retardancy of the NS filled EPDM/KF hybrid composite insulations is based on the fiber/matrix adhesion. Maleic anhydride grafting confers polarity to the nonpolar rubber matrix. The char residues of the insulations inspected by scanning electron microscopy and energy dispersive spectroscopy are depicting a rigid and rough surface by the optimal composites, which can aid in better insulation. The optimal formulation of the hybrid composites exhibited a 220% enhancement in char residue with improved thermal stability and mechanical properties.     

Butyl pyrene containing poly(arylene ethynylene)s for highly sensitive and selective sensing of TNT

A series of poly(arylene ethynylene)s (PAEs) containing ^tbutyl pyrene in the main chain were synthesized for nitroaromatic sensors. As control, similar polymers containing unsubstituted pyrene were also synthesized. The sensory properties of the polymers were studied towards various nitroaromatic compounds like trinitrotoluene (TNT), dinitrotoluene (DNT), nitrotoluene (NT), nitrobenzene (NB) and picric acid (PA) in solution as well as vapor state. Interestingly, all the ^tbutyl substituted pyrene containing polymers showed higher sensitivity than the corresponding unsubstituted pyrene containing polymers. Moreover, the polymers showed high sensitivity towards TNT as compared to the other nitroaromatic compounds. The sensitivity of one of the polymer PB was found several folds higher than that of the similar reported polymer containing unsubstituted pyrene ring. In addition, ^tbutyl pyrene containing polymers were found to have improved molecular weight, thermal stability, fluorescence quantum yield, film forming properties and solubility in common organic solvents as compared to the control polymers.     

Development of Richtmyer-Meshkov and Rayleigh-Taylor instability in the presence of magnetic field

Fluid instabilities like Rayleigh-Taylor (R-T), Richtmyer-Meshkov (R-M) and Kelvin-Helmholtz (K-H) instability can occur in a wide range of physical phenomenon from astrophysical context to Inertial Confinement Fusion (ICF). Using Layzer's potential flow model, we derive the analytical expressions of growth rate of bubble and spike for ideal magnetized fluid in R-T and R-M cases. In the presence of transverse magnetic field, the R-M and R-T instabilities are suppressed or enhanced depending on the direction of magnetic pressure and hydrodynamic pressure. Again the interface of two fluid may oscillate if both the fluids are conducting. However, it is observed that the magnetic field has no effect in linear case.     

Comparison of the Microstructures and Mechanical Properties in the Overlapping Region of Low Carbon Steel Additive Bead Fabricated by WAAM and FSP

Metallurgical and Materials Transactions A - The periodic structural characteristics of the grains in the overlapping region of the WAAM deposited additive bead translate into spatially dependent...