Optically active nanomaterials for environmental remediation

In recent years optically active nanomaterials have opened up a number of frontiers, especially in life science and environmental protection. Novel hybrid nanomaterials based on wide band gap oxides (TiO2) and Ln3+ doped rare earth compounds (down- and up-conversion luminescence materials) obtained through innovative processing will be presented from the viewpoint of their potential application for light harvesting and photocatalysis

Spatial rogue waves in photorefractive SBN crystals

We report on the excitation of large-amplitude waves, with a probability of around 1% of total peaks, on a photorefractive SBN crystal by using a simple experimental setup at room temperature. We excite the system using a narrow Gaussian beam and observe different dynamical regimes tailored by the value and time rate of an applied voltage. We identify two main dynamical regimes: a caustic one for energy spreading and a speckling one for peak emergence. Our observations are well described by a two-dimensional Schr\"odinger model with saturable local nonlinearity.Comment: 4 pages, 4 figure

Facile synthesis of hydrophilic polymer-capped upconverting NaYF4:Yb,Er particles

Over the last decade, solvothermal decomposition of organometallic compounds has been indicated as one of the most convenient method for the synthesis of monodisperse lanthanide doped upconverting fluorides. Due to their hydrophobic nature such particles could not be used for a conjugation of the molecular targeting agents which is necessary for optical imaging of biological tissues. In this work, hydrophilic NaYF4:Yb,Er (17 mol% Yb; 3mol% Er) nanoparticles were synthesized by facile one-pot hydrothermal synthesis performed with a help of chitosan (CS) and poly(acrylic acid) (PAA). Obtained powders were analyzed by X-ray powder diffraction (XRPD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopy. The obtained results implied that particle size, shape and surface characteristics are dependent on the polymer choice. Although both powders crystallize in the same crystal arrangement (cubic, Fm-3m) more intense red emission, assigned to the Er3+ 4F9/2 → 4I15/2 electronic transitions, characterize spherical NaYF4:Yb,Er@CS particles. To asses a biological safety of their use, viability of the human gingival fibroblasts (HFG) was additionally tested by a colorimetric MTT assay

Facile synthesis of hydrophilic polymer-capped upconverting NaYF4:Yb,Er particles

Over the last decade, solvothermal decomposition of organometallic compounds has been indicated as one of the most convenient method for the synthesis of monodisperse lanthanide doped upconverting fluorides. Due to their hydrophobic nature such particles could not be used for a conjugation of the molecular targeting agents which is necessary for optical imaging of biological tissues. In this work, hydrophilic NaYF4:Yb,Er (17 mol% Yb; 3mol% Er) nanoparticles were synthesized by facile one-pot hydrothermal synthesis performed with a help of chitosan (CS) and poly(acrylic acid) (PAA). Obtained powders were analyzed by X-ray powder diffraction (XRPD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopy. The obtained results implied that particle size, shape and surface characteristics are dependent on the polymer choice. Although both powders crystallize in the same crystal arrangement (cubic, Fm-3m) more intense red emission, assigned to the Er3+ 4F9/2 → 4I15/2 electronic transitions, characterize spherical NaYF4:Yb,Er@CS particles. To asses a biological safety of their use, viability of the human gingival fibroblasts (HFG) was additionally tested by a colorimetric MTT assay

Facile synthesis of hydrophilic polymer-capped upconverting NaYF4:Yb,Er particles

Over the last decade, solvothermal decomposition of organometallic compounds has been indicated as one of the most convenient method for the synthesis of monodisperse lanthanide doped upconverting fluorides. Due to their hydrophobic nature such particles could not be used for a conjugation of the molecular targeting agents which is necessary for optical imaging of biological tissues. In this work, hydrophilic NaYF4:Yb,Er (17 mol% Yb; 3mol% Er) nanoparticles were synthesized by facile one-pot hydrothermal synthesis performed with a help of chitosan (CS) and poly(acrylic acid) (PAA). Obtained powders were analyzed by X-ray powder diffraction (XRPD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopy. The obtained results implied that particle size, shape and surface characteristics are dependent on the polymer choice. Although both powders crystallize in the same crystal arrangement (cubic, Fm-3m) more intense red emission, assigned to the Er3+ 4F9/2 → 4I15/2 electronic transitions, characterize spherical NaYF4:Yb,Er@CS particles. To asses a biological safety of their use, viability of the human gingival fibroblasts (HFG) was additionally tested by a colorimetric MTT assay

Tetracycline Removal through the Synergy of Catalysis and Photocatalysis by Novel NaYF4:Yb,Tm@TiO2-Acetylacetone Hybrid Core-Shell Structures

Novel hybrid core-shell structures, in which up-converting (UC) NaYF4:Yb,Tm core converts near-infrared (NIR) to visible (Vis) light via multiphoton up-conversion processes, while anatase TiO2-acetylacetonate (TiO2-Acac) shell ensures absorption of the Vis light through direct injection of excited electrons from the highest-occupied-molecular-orbital (HOMO) of Acac into the TiO2 conduction band (CB), were successfully synthesized by a two-step wet chemical route. Synthesized NaYF4:Yb,Tm@TiO2-Acac powders were characterized by X-ray powder diffraction, thermogravimetric analysis, scanning and transmission electron microscopy, diffuse-reflectance spectroscopy, Fourier transform infrared spectroscopy, and photoluminescence emission measurement. Tetracycline, as a model drug, was used to investigate the photocatalytic efficiencies of the core-shell structures under irradiation of reduced power Vis and NIR spectra. It was shown that the removal of tetracycline is accompanied by the formation of intermediates, which formed immediately after bringing the drug into contact with the novel hybrid core-shell structures. As a result, ~80% of tetracycline is removed from the solution after 6 h

Effects of different polymers and solvents on crystallization of theNaYF4:Yb/Er phase

Up-converting NaYF4:Yb,Er nanoparticles were obtained by polymer-assisted solvothermal synthesis using a common solution of hydrated RE nitrates in ethanol or ethylene glycol. It was shown that polymer choice (polyacrylic acid—PAA, polyvinylpyrrolidone—PVP and chitosan—CS) controls the size and shape of NaYF4:Yb,Er nanoparticles, while the solvent type and pH value affect their crystallinity. Consequently, the spherical nanoparticles of a cubic (α) phase, the average size of which ranged from 60 to 140 nm, were obtained either when PVP/ethanol or PVP/ethylene glycol were used solely during synthesis, whereas NaOH addition induced hexagonal (β) phase nucleation. The formation of the hierarchically organized spherical aggregates and nanofoils was observed when CS and PAA were used during synthesis, respectively. The average crystallite size, microstrain, doping level, lattice parameters, as well as, the presence of the certain ligands on the particle surface were determined and correlated with the intensity of visible-light emission observed under 980 nm laser-diode excitation.This is the peer-reviewed version of the article: Vukovic, M., Dinic, I., Nikolic, M.G., Marinkovic, B.A., Costa, A.M.L.M., Radulovic, K., Milosevic, O., Mancic, L., 2019. Effects of different polymers and solvents on crystallization of theNaYF4:Yb/Er phase. Bull Mater Sci 43, 2. [https://doi.org/10.1007/s12034-019-1975-1

Facile synthesis of hydrophilic polymer-capped upconverting NaYF4:Yb,Er particles

Over the last decade, solvothermal decomposition of organometallic compounds has been indicated as one of the most convenient method for the synthesis of monodisperse lanthanide doped upconverting fluorides. Due to their hydrophobic nature such particles could not be used for a conjugation of the molecular targeting agents which is necessary for optical imaging of biological tissues. In this work, hydrophilic NaYF4:Yb,Er (17 mol% Yb; 3mol% Er) nanoparticles were synthesized by facile one-pot hydrothermal synthesis performed with a help of chitosan (CS) and poly(acrylic acid) (PAA). Obtained powders were analyzed by X-ray powder diffraction (XRPD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopy. The obtained results implied that particle size, shape and surface characteristics are dependent on the polymer choice. Although both powders crystallize in the same crystal arrangement (cubic, Fm-3m) more intense red emission, assigned to the Er3+ 4F9/2 → 4I15/2 electronic transitions, characterize spherical NaYF4:Yb,Er@CS particles. To asses a biological safety of their use, viability of the human gingival fibroblasts (HFG) was additionally tested by a colorimetric MTT assay

Microencapsulated biofertilizer formulation: product development and effect on growth of green pepper seedlings

Aim of the study: This study aimed to formulate a novel, commercially applicable biofertilizer, to optimize the microencapsulation procedure of Bacillus subtilis NCIM 2063 and examine the stability and phytostimulatory effects of obtained formulation. Area of the study: Southestern Serbia. Material and methods: Microbial powder formulations were prepared using spray drying with maltodextrin as a carrier. The spray drying conditions were set according to Box-Benkhen experimental desing. The effect of the formulation was tested on green pepper (Capsicum annuum) seeds in controled conditions. Main results: Response surface models were developed. All of the models were statistically significant, adequately fitted and reproducible. The maximum achieved values of viability and yield in a formulation were 1.99·109 CFU/g and 96.8%, respectively, whilst the driest formulation had 1.44% moisture. The following optimum conditions were proposed for the spray drying procedure: an inlet air temperature of 133 °C, maltodextrin concentration of 50 g/L and a feed flow rate of 6.5 mL/min. The obtained microbial formulation had a high survival rate after being stored at room temperature over a 1--year period. Its application on green pepper seeds had beneficial effect on plant height, leaf dry weight and chlorophyll content of the seedlings. Research highlights: B. subtilis was successfully microencapsulated on maltodextrin as a carrier. Interaction effects between the process variables were fully explained and statistically significant models were developed. In addition to biocontrol properties formulation had a phytostimulatory effect, excellent stability and satisfactory physical properties. © 2022 CSIC

Mechanochemical synthesis of multiferroic yttrium manganite

Multiferroic yttrium manganite (YMnO3) is known as a material that exhibits both ferromagnetic and ferroelectric properties making it interesting for various technological applications. In this work single-phased YMnO3 was prepared for the first time by mechanochemical synthesis in a planetary ball mill. The YMnO3 can be formed directly from the highly activated constituent oxides, Y2O3 and Mn2O3, after 60 min of milling time and subsequently grows during prolonged milling. The cumulative energy introduced into the system during milling for 60 min was 86 kJ/g. X-ray analysis indicates that the as-prepared samples crystallize majority with hexagonal (P63cm) and minorly with orthorhombic (Pnma) YMnO3 structure. The morphology, structure and chemical composition of the powder were investigated by SEM with EDS and TEM. The magnetic properties of the obtained YMnO3 powders were found to change as a function of milling time in a manner consistent with the variation in the nanocomposite microstructure