BackgroundThe release of heavy metal-containing nanoparticles (NP) into the environment may be harmful to the efficacy of beneficial microbes that function in element cycling, pollutant degradation and plant growth. Nanoparticles of Ag, CuO and ZnO are of interest as antimicrobials against pathogenic bacteria. We demonstrate here their antimicrobial activity against the beneficial soil microbe, Pseudomonas putida KT2440.ResultsToxicity was detected in a KT2440 construct possessing a plasmid bearing the luxAB reporter genes. "As manufactured" preparations of nano- Ag, -CuO and -ZnO caused rapid dose-dependent loss of light output in the biosensor. Cell death accompanied loss in Lux activity with treatments by nano-Ag and -CuO, but with -ZnO the treatments were bacteriostatic rather than bactericidal. Bulk equivalents of these products showed no inhibitory activity, indicating that particle size was determinant in activity. Flow Field-Flow Fractionation (FlFFF) of an aqueous suspension of the nano-CuO and ZnO revealed a small proportion of 5 nm NP and aggregated particulates with sizes ranging between 70 nm and 300 nm; the majority portion of material was aggregated into particles larger than 300 nm in size. Thus within the commercial preparation there may be microbially active and inactive forms.ConclusionThe "as-made" NP of Ag, CuO and ZnO have toxic effects on a beneficial soil microbe, leading to bactericidal or bacteriostatic effects depending on the NP employed. The lack of toxicity from bulk materials suggests that aggregation of the NP into larger particles, possibly by factors present in the environment may reduce their nontarget antimicrobial activity.

A recently proposed model potential is used to study the superconducting state parameters viz. electron-phonon coupling strength λ, Coulomb pseudopotential µ * , transition temperature T C , isotope effect exponent α and effective interaction strength N O V of 40 metallic glasses of simple, non-simple as well as transition metals. The advanced screening function due to Sarkar et al. has been employed to include the exchange and correlation effects. Instead of Vegard's law, the use of pseudo-alloy-atom model in the investigation of superconducting state properties of metallic glasses is proposed and found successfully.

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Our well-recognized pseudopotential is used to investigate the superconducting state parameters viz; electron-phonon coupling strength λ, Coulomb pseudopotential µ * , transition temperature T c , isotope effective exponent α and interaction strength N 0 V for the In 1−x Zn x and In 1−x Sn x binary alloys. We have incorporated six different types of local field correction functions, proposed by Hartree, Taylor, Vashistha-Singwi, Ichimaru-Utsumi, Farid et al and Sarkar et al to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of the various exchange and correlation functions is concluded from the present study. The comparison with other such theoretical values is encouraging, which confirms the applicability of our model potential in explaining the superconducting state parameters of binary mixture.

The study of the superconducting state parameters (SSP) viz. electron-phonon coupling strength λ, Coulomb pseudopotential µ * , transition temperature T C , isotope effect exponent α and effective interaction strength N 0 V of In-based binary alloys In 1−x Nax, In 1−x Mgx, In 1−x Znx, In 1−x Tlx, In 1−x Snx, In 1−x Pbx and In 1−x Bix have been made extensively in the present work using a model potential. To explain electron-ion interaction pseudo-alloy-atom (PAA) model is applied for the first time instead of Vegard's Law. A considerable influence of various exchange and correlation functions on λ and µ * is found from the present study. It is also concluded that T C strongly depends on the value of the effective valence Z * of binary alloys.

Investigation of the binding interactions of synthesized multi-walled carbon nanotubes (MWCNTs) with SARS-CoV-2 virus.

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