Green Synthesis, Characterization and Antibacterial Study of Ag-Au Bimetallic Nanocomposite using Tea Powder Extract

Synthesis of metal nanoparticles using plant extracts is attracted much to the recent researchers due to its simplicity, which integrates chemical technology. Special attention is given to the green synthesis of nanoparticles by easily available plants with an eco-friendly system compared to other conventional methods. Silver-Gold nanocomposite (Ag-Au NCp’s) is synthesized by bi reduction of silver nitrate and gold chloride. These metal salts are simultaneously reduced by tea extract to form respective silver and gold nanocomposite. The structure and morphology of as-prepared Ag-Au NCp’s sample were characterized by employing powder X-ray diffraction (XRD) tool and by Scanning Electron Micrograph (SEM) tool, respectively. Fourier Transform Infrared (FTIR) spectral study was undertaken to know the bonding in the prepared silver sample. Morphology and particle size of the above composite was studied by the Transmission electron microscope (TEM) tool. Energy-dispersive X-ray analysis (EDX) study was undertaken to know the formation of Ag-Au NCp’s. Antibacterial activity study is undertaken to know its biological behavior.

The Thermocouple Revisited: The Thomson Effect

Measurements of Thomson (later Lord Kelvin) coefficients are made in an evacuated region on a silver sample with a novel transducer in temperature intervals {T_{A}}\pm 20\hspace{0.1667em}\text{K}, where the {T_{A}} are very carefully controlled ambient temperatures. This is the first systematic examination of Thomson coefficients in these temperature intervals. The Thomson coefficients when plotted against T, the temperature of measurement, are found to be discontinuous precisely at {T_{A}}. When the Thomson coefficients are multiplied by a transformation involving T and {T_{A}}, a linear curve in T results. Examinations here of measurements of Thomson coefficients produced by others show multiple values at T in some cases and odd behavior in other cases. Multiplying the results of others by the transformation discovered here almost always produces linear curves. The conclusions are the following. (1) Thomson’s explicit assumption that the Thomson effect involves no energy exchange with surroundings was wrong. (2) Any non-equilibrium thermodynamic approach to deriving the Thomson effect must take into account the energy exchange with the surroundings and consequently must be made in three dimensions. (3) From the work here and that of others, the energy exchange with the environment is probably mostly thermal radiation.

CRITICAL CURRENT DEPENDENCE ON AXIAL STRAIN AT LN2 TEMPERATURE OF AG-CLAD BI(2223) TAPES

The critical currents (1 μvolt/cm criterion) or commercially supplied tapes of Bi2Sr2Ca2Cu3OX (Bi(2223)) in Ag were measured at LN2 temperature as axial stresses of up to 220 MPa were applied. The critical current decreased linearly with increasing strain up to the point or plastic deformation, whereupon it dropped discontinuously to less than 10% or the unstressed value. The resistivity of a pure silver sample was also tested at LN2 temperature it was constant with increasing stress up to (the same) point of plastic deformation; then it increased linearly. Youngs modulus and the yield strength at LN2 and room temperature are compared.

Modification of Fracture Energy of Niobium/sapphire Interface By Impurity Doping

ABSTRACTThe effect of interface composition on the fracture energy and fracture toughness of the niobium/sapphire system was studied. Niobium films with thickness of 100 nm were deposited on (0001) sapphire substrates by physical vapor deposition (PVD). The interface was doped with silver to reduce the interfacial cohesion. The amount of silver ranged from less than 2.1 monolayers to 6.4 monolayers as measured by Rutherford backscattering spectrometer (RBS). The microscratch test was used in determining the interfacial fracture energy and the interfacial fracture toughness. Both interfacial fracture energy Gc and fracture toughness Kc decrease non-linearly with the amount of silver, and level off for samples with larger silver thickness ( > 4.2 monolayers). The values of interfacial fracture energy range from 3.43 J/m2 - 9.20 J/m2 for the sample doped with 2.1 monolayer silver (sample B) to 0.05 J/m2 - 0.5 J/m2 for samples with silver levels above 4.2 monolayers (samples D and E). The corresponding fracture toughnesses are 0.80 MPa-m½ - 1.29 MPa-m½ for sample B and 0.09 MPa-m½ - 0.30 MPa-m½ for samples D and E.