ABSTRACT
Zinc oxide (ZnO) nanostructures are widely used in various fields of science and technology due to their properties and ease of fabrication. To achieve the desired characteristics for subsequent device application, it is necessary to develop growth methods allowing for control over the nanostructures' morphology and crystallinity governing their optical and electronic properties. In this work, we grow ZnO nanostructures via hydrothermal synthesis using surfactants that significantly affect the growth kinetics. Nanostructures with geometry from nanowires to hexapods are obtained and studied with photoluminescence (PL) spectroscopy. Analysis of the photoluminescence spectra demonstrates pronounced exciton on a neutral donor UV emission in all of the samples. Changing the growth medium chemical composition affects the emission characteristics sufficiently. Apart the UV emission, nanostructures synthesized without the surfactants demonstrate deep-level emission in the visible range with a peak near 620 nm. Structures synthesized with the use of sodium citrate exhibit emission peak near 520 nm, and those with polyethylenimine do not exhibit the deep-level emission. Thus, we demonstrate the correlation between the hydrothermal growth conditions and the obtained ZnO nanostructures' optical properties, opening up new possibilities for their precise control and application in nanophotonics, UV-Vis and white light sources.
ABSTRACT
Periodic outbreaks of African swine fever virus (ASFV) infection around the world threaten local populations of domestic pigs with lethal disease and provide grounds for pandemic spread. Effective vaccination may bring this threat under control. We investigated the effectiveness of select peptides mimicking viral proteins in establishing a protective immune response. Forty-six synthetic peptides based on the analysis of the complete nucleotide sequence of ASFV were tested for immunogenicity in mice. The 17 best immune response-inducing peptide candidates were selected for further investigation. Twenty-four domestic pigs, 3-4 months old and weighing 20-25 kg, were divided into six groups (n = 4) and immunized by subcutaneous injection using a standard three-round injection protocol with one of four peptide combinations prepared from the 17 peptides (Groups 1-4) or with carrier only (Group 5). Group 6, the control, was not vaccinated. Animal body temperature and behavior were monitored during and post immunization for health assessment. Two weeks after the last round of immunizations, the pigs were infected with live ASFV (Espania 70) at 6.0 Ig GAE50/cm3, and the survival rate was monitored. Blood samples were collected for analysis the day before infection and on days 3, 7 and 10 post-infection, or from deceased animals. The serum titers of specific immunoglobulins against synthetic peptides and whole inactivated ASFV were determined by enzyme immunoassay before and after infection. The presence of viral DNA in blood serum samples was determined by polymerase chain reaction. Viral infection activity in blood sera was determined by heme absorption in cultured porcine bone marrow and porcine leukocyte cells. Repeating the injection of synthetic peptides in both the mice and pigs produced an immune response specific to individual peptides, which differed widely in the intensity scale. Specific anti-whole virus immunoglobulin binding activity in the swine serum samples from all groups was below the detection limit. Viral DNA was positively identified in all the samples infected with viral preparations. Viral infection activity was present in all the infected animals and steadily increased with time. On day 3 after infection, the viral titer was significantly lower in Groups 1 and 3 than in the unvaccinated controls. In deceased animals, the viral titer was significantly lower in Groups 1 and 3 than in the controls. All infected animals died within 17 days of infection. The average survival rate was significantly higher in Groups 1 and 3 (12.0 and 14.3 days, respectively) than in the controls (9.8 days). Vaccination with specific synthetic peptides significantly delayed mortality in domestic pigs infected with ASFV. These results justify further investigation aimed at developing an effective vaccine against ASFV infection.
