Comparison of bactericidal activities of silver nanoparticles with common chemical disinfectants

Engineered nanomaterials display significant advantages due to their unique nanostructure, along with their tuneable properties for the designed application. Silver nanoparticles (Ag-NPs) have drawn attention due to their use as potent bactericidal agents and were characterized in this research to provide an understanding of the interaction between nanomaterials and bacteria. This work presents the bactericidal performance of Ag-NPs using Escherichia coli (E. coli) as a model microorganism. Several state-of-the-art techniques, such as high-angle annular dark-field detector in scanning transmission electron microscopy, and energy filtered imaging in electron energy loss spectroscopy, were employed to obtain nanostructural and elemental information. The bactericidal activities of Ag-NPs were then compared with two commonly used disinfectants, sodium hypochlorite (NaClO) and phenol (C(6)H(5)OH). These two chemical disinfectants exhibited rapid bactericidal activity, showing a minimal bactericidal concentration (MBC) of 16 parts-per-million (ppm) and 16 part-per-thousand (ppth), respectively for NaClO and C(6)H(5)OH within about 10 min. In contrast, Ag-NPs exhibit slow but long-term bactericidal effect demonstrating MBCs of 0.6 parts-per-million (ppm) within 6h when used as disinfectant. An advantage using Ag-NPs to inactivate E coli at low dosages is negligible environmental waste or hazardous by-products. The results showed that Ag-NPs caused bacterial inactivation by a mechanism involving several steps, including cell wall and cytoplasmic membrane damage.     

Experimental and Theoretical Studies of Green Synthesized Cu2O Nanoparticles Using Datura Metel L

In biomedical applications, Cu₂O nanoparticles are of great interest. The bioengineered route is eco-friendly for the synthesis of nanoparticles. Therefore, in the present study, there is an attempt to synthesis Cu₂O nanoparticles using Datura metel L. The synthesized nanoparticles were characterized by UV–Vis, XRD, and FT-IR. UV–Vis results suggest the presence of hyoscyamine, atropine in Datura metel L, and also, nanoparticles formation has been confirmed by the presence of absorption peak at 790 nm. The average crystallite size (19.56 nm) was obtained by XRD. FT-IR was also used to confirm the different functional groups. Fourier Power Spectrum was also employed to examine the synthesized nanomaterials spectrum data to emphasize the peak of the prominent frequencies. Density functional theory (DFT) was also utilized to assess the energy of the substance over time, which appears to indicate a stable molecule. Furthermore, calculated energies, thermodynamic properties (such as enthalpies, entropies, and Gibbs-free energies), modeled structures of complexes, crystals, and clusters, and predicted yields, rates, and regio- and stereospecificity of reactions were all in good agreement with experimental results. Overall, the results show that the successful production of Cu₂O nanoparticles with Datura metel L. corresponds to theoretical research.

     

Millimeter wave generation through frequency 12-tupling using DP-polarization modulators

The polarization modulators are being utilized for the millimeter wave (MM-Wave) generation because of their bias drift free operation and high extinction ratio. In this work, an optical millimeter wave generation through frequency 12 tupling using dual parallel polarization modulator (DP-PolM) is demonstrated. By setting RF drive voltage and proper polarization angle of the DP-PolM, the frequency 12-tupled optical millimeter is generated with an optical sideband suppression ratio (OSSR) of 37.76 dB and radio frequency sideband suppression ratio (RFSSR) of 31.67 dB. A good agreement between simulation and theoretical approach is achieved. Further, impact of non ideal parameters on the OSSR, RFSSR and BER are also analysed and presented.     

Multigrid methods in density functional theory

A multigrid method for real-space solution of the Kohr-Sham equations is presented. By using this multiscale approach, the problem of critical slowing down typical of iterative real-space solvers is overcome. The method scales linearly in computer time with the number of electrons if the orbitals are localized. Here, we describe details of our multigrid method, present preliminary many-electron numerical results illustrating the efficiency of the solver, and discuss its strengths and limitations. © 1997 John Wiley & Sons, Inc.