The Role of Flavonoids in Invasion Strategy of Solidago canadensis L.

This study provides data on the problem of potential complexation of phenolic compounds synthesized by the plants Solidago canadensis L. and Solidago gigantea Ait. with ammonium forms of nitrogen, partly immobilized in the soil. A comparative analysis of secondary metabolites of the studied plants was performed by HPLC. The leaves of invasively active Solidago canadensis contain nine times more rutin than the plants of Solidago gigantea. Adding to the leaf extracts (v/v1/20) aqueous ammonia solution to pH 8.0 on the chromatograms decreases the intensity or completely causes peaks of flavonoids to disappear; instead, there are peaks of new polar substances (tR 1.5 and 2.0 min). The selective effect of the phenol-ammonium complex on various plant species was revealed. At a concentration of 20 μg/mL, these substances stimulated the formation of lateral roots in soybean seedlings and chrysanthemum cuttings. The suppression of root growth in radish seedlings occurred at a concentration of flavonoids in the extract of 25 μg/mL. In addition, a positive chemotaxis of the Pseudomonas putida (PGPR) was detected in the nitrogen-containing complex based on rutin (5 μg/mL). The identified feature allows PGPR colonization of the root system of Solidago canadensis with corresponding changes in the structure of the microbial community. The ability of the obtained nitrogen-containing polar complexes to regulate the growth processes of plants at extremely low concentration points to promising research in this direction.

Synthesis of holmium orthoferrite nanoparticles by the co-precipitation method at high temperature

Holmium orthoferrite HoFeO3 nanoparticles were synthesized by a simple co-precipitation method via the hydrolysis of Ho (III) and Fe (III) cations in boiling water with 5% aqueous ammonia solution. After annealing the precipitate at 750 and 850 °C for 1 hour, the single-phase HoFeO3 product formed with particle size < 50 nm. The synthesized nanopowders are paramagnetic materials with remanent magnetization Mr < 0.01 emu·g-1, the coercive force Hc = 20÷21 Oe, and magnetization Ms ~ 2.73 emu·g-1 at 300 K in a maximum field of 16,000 Oe.

Thin Film Fabrication and Characterization of Layered Rock Salt LiCoO2 on Quartz Glass Spray-Coated with an Aqueous Ammonia Solution Involving Metal Acetates

A LiCoO2 thin film on a quartz glass substrate was fabricated by a wet process involving heat treatment of a precursor film spray-coated with an aqueous ammonia solution containing LiCH3COO and Co(CH3COO)2. The precursor film formed onto the substrate at 180 °C in air, and was heat treated at 500 °C in air for 0.5 h. The obtained film was spin-coated further with an ethanol-based precursor solution containing identical metal acetates, and heat treated at 500 °C in air for 0.5 h. The X-ray diffraction pattern of the resultant film showed only peaks assignable to the layered-rock-salt LiCoO2. Raman spectroscopy measurements revealed vibrational modes assignable to layered rock salt LiCoO2, with minor content of less than 5 mol% of spinel-type Co3O4. The field emission scanning electron microscopy images indicated that the resultant film was 0.21 μm thick, had no voids, and was a combination of small rounded grains measuring 18 nm in diameter and hexagonal grains larger than 0.2 μm in length. The Hall effect measurements indicated that the resultant thin film was a p-type semiconductor with electrical resistivity of 35(2) Ω·cm and a carrier concentration and carrier mobility of 8(2) × 1016 cm−3 and 2(1) cm2·V−1·s−1, respectively.