A joint study of the rotational dynamics and free volume in amorphous 1-propanol (1-PrOH) as a prototypical monohydroxy alcohol by electron spin resonance (ESR) or positron annihilation lifetime spectroscopy (PALS), respectively, is reported. The dynamic parameters of the molecular spin probe 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and the annihilation ones of the atomic ortho-positronium (o-Ps) probe as a function of temperature are compared. A number of coincidences between various effects in the ESR and PALS responses at the corresponding characteristic ESR and PALS temperatures were found suggesting a common origin of the underlying dynamic processes that were identified using viscosity (VISC) in terms of the two-order parameter (TOP) model and broadband dielectric spectroscopy (BDS) data.
Development
of new types of antibacterial coatings or nanocomposites
is of great importance due to widespread multidrug-resistant infections
including bacterial infections. Herein, we investigated biocompatibility
as well as structural, photocatalytic, and antibacterial properties
of photoactive hydrophobic carbon quantum dots/polyurethane nanocomposite.
The swell-encapsulation-shrink method was applied for production of
these nanocomposites. Hydrophobic carbon quantum dots/polyurethane
nanocomposites were found to be highly effective generator of singlet
oxygen upon irradiation by low-power blue light. Analysis of conducted
antibacterial tests on Staphyloccocus aureus and Escherichia coli showed 5-log bactericidal effect of these
nanocomposites within 60 min of irradiation. Very powerful degradation
of dye (rose bengal) was observed within 180 min of blue light irradiation
of the nanocomposites. Biocompatibility studies revealed that nanocomposites
were not cytotoxic against mouse embryonic fibroblast cell line, whereas
they showed moderate cytotoxicity toward adenocarcinomic human epithelial
cell line. Minor hemolytic effect of these nanocomposites toward red
blood cells was revealed.
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