Spintronic terahertz emitters with integrated metallic terahertz cavities.

Spintronic terahertz emitters (STEs), based on optical excitation of nanometer thick ferromagnetic/heavy metal (FM/HM) heterojunctions, have become important sources for the generation of terahertz (THz) pulses. However, the efficiency of the optical-to-THz conversion remains limited. Although optical techniques have been developed to enhance the optical absorption, no investigations have studied the application of THz cavities.

Damage of the bacterial cell envelope by antimicrobial peptides gramicidin S and PGLa as revealed by transmission and scanning electron microscopy.

Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the ultrastructural changes in bacteria induced by antimicrobial peptides (AMPs). Both the beta-stranded gramicidin S and the alpha-helical peptidyl-glycylleucine-carboxyamide (PGLa) are cationic amphiphilic AMPs known to interact with bacterial membranes. One representative Gram-negative strain, Escherichia coli ATCC 25922, and one representative Gram-positive strain, Staphylococcus aureus ATCC 25923, were exposed to the AMPs at sub-MICs and supra-MICs in salt-free medium.