BackgroundDue to bacterial resistance to antibiotics there is a need for new antimicrobial agents. In this respect nanoparticles can be used as they have expressed antibacterial activity simultaneously being more reactive compared to their bulk material. The action of zinc (II), titanium (IV), copper (II) and (I) oxides thin films with nanostructured surface and silver nanoscale particles on Enterococcus hirae and Escherichia coli growth and membrane activity was studied by using microbiological, potentiometric and spectrophotometric methods.ResultsIt was revealed that sapphire base plates with deposited ZnO, TiO2, CuO and Cu2O nanoparticles had no effects neither on E. hirae nor E. coli growth both on agar plates and in liquid medium. Concentrated Ag nanoparticles colloid solution markedly affected bacterial growth which was expressed by changing growth properties. E. hirae was able to grow only at <1:200 dilutions of Ag nanoparticles while E. coli grew even at 1:10 dilution. At the same time Ag nanoparticles directly affected membranes, as the FOF1-ATPase activity and H+-coupled transport was changed either (E. coli were less susceptible to nanoparticles compared to E. hirae). Ag nanoparticles increased H+ and K+ transport even in the presence of N,N′-dicyclohexylcarbodiimide (DCCD), inhibitor of FOF1. The stoichiometry of DCCD-inhibited ion fluxes was disturbed.ConclusionsThese results point out to distinguishing antibacterial effects of Ag nanoparticles on different bacteria; the difference between effects can be explained by peculiarities in bacterial membrane structure and properties. H+-K+-exchange disturbance by Ag nanoparticles might be involved in antibacterial effects on E. hirae. The role of FOF1 in antibacterial action of Ag nanoparticles was shown using atpD mutant lacked β subunit in F1.

The principles and results of design of microwave diplexers on dielectric resonators (DR) for high level (over 100W) signals are discussed. Diplexers have insertion losses less than 1.5 dB at 2,4-2,7 % passband and 90 dB isolation between channels.

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Аннотация -Представлены результаты разработки полосно-пропускающих фильтров на основе открытых диэлектрических резонаторов для работы в трактах с непрерывной мощностью порядка 100 Вт. Предложена конструкция резонансного звена, обеспечивающая высокие электрические характеристики фильтра при хорошем теплоотводе. В частности, фильтр С диапазона имеет в полосе пропускания шириной 2,6 % потери не более 1,2 дБ при коэффициенте прямоугольности 2,5 по уровню 90 дБ, широкую полосу заграждения -ослабление более 90 дБ во всем С диапазоне, и эффективное подавление паразитных полос пропускания -не менее 60 дБ, в L -Xc диапазонах.Abstract -The principles and results of the design of microwave band-pass filters on dielectric resonators (DR) for high level (over 100 W) signals are discussed. Filters have insertion losses less than 1.2 dB at 2.6 % passband, 6.25 % passband at 90 dB level and spurious passband suppression over 60 dB.

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