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Methods for the synthesis of LaNi1/3Sb5/3O6 with a rosiaite structure have been developed using citrate method and coprecipitation followed by annealing. The influence of synthesis conditions on the morphology of the samples has been demonstrated. A comparative analysis of the catalytic properties of LaNi1/3Sb5/3O6 synthesized by various methods, in the reaction of CO oxidation has been carried out. The catalyst synthesized by the citrate method demonstrated the greatest efficiency and stability (the temperature of 90% CO conversion was T90 = 336°C). The LaNi1/3Sb5/3O6 surface was studied before and after catalysis by in situ diffuse reflectance IR spectroscopy, X-ray photoelectron spectroscopy, and temperature-programmed O2 desorption. It has been shown that the catalytic oxidation of CO on the LaNi1/3Sb5/3O6 surface proceeds according to the Mars–van Krevelen mechanism and is accompanied by redox Sb3+ ↔ Sb5+ processes. It has been established that no contamination of the sample surface occurs during the catalysis process. [ABSTRACT FROM AUTHOR]

The development of modern building materials science involves the process of designing innovative materials that exhibit unique characteristics, such as energy efficiency, environmental friendliness, self-healing ability, and photocatalytic properties. This can be achieved by modifying cement with nano- and fine-dispersed additives that can give the material new properties. Such additives include a number of compounds based on the TiO2-Bi2O3 system. These compounds have photocatalytic activity in the near-UV and visible range of the spectrum, which can serve to create photocatalytic concretes. Here, the purpose of this scientific study was to synthesize compounds based on the TiO2-Bi2O3 system using two methods in order to identify the most optimal variant for creating a composite material and determine its properties. Within the framework of this article, two methods of obtaining a photocatalytically active additive based on the TiO2-Bi2O3 system are considered: the solid-state and citrate-based methods. The photocatalytic, mechanical and structural properties of composites containing the synthesized additive are investigated. In this study, it was found that for the creation of photocatalytic concretes, it is advisable to use cement compositions with a bismuth titanate content of 3–10 wt.%. of the cement content, regardless of the method of obtaining the additive. However, the most optimal composition is one containing 5 wt.% of the synthesized additive. It is noted that compositions containing 5% by weight of bismuth titanate demonstrate photocatalytic activity and also show an increase in strength on the first day of hardening by 10% for the solid-state method and 16% for the citrate method. [ABSTRACT FROM AUTHOR]

Hexagonal ferrites with the formula SrxBa(1−x)Fe12O19 (x = 0; 0.3; 0.5; 0.7; and 1) were prepared using the citrate method. The main feature of this synthesis is a relatively low calcination temperature of 700 °C. An X-ray diffraction study revealed a single-phase material. According to SEM, the particles were 50−70 nm in diameter. The Curie temperature of the samples that were determined using the DSC method varied in a very narrow range of 455−459 °C. Analysis of the magnetic hysteresis loops obtained at 300 K and 50 K indicated all samples as magnetically hard materials in a single-domain state. The maximal magnetic characteristics encompass strontium hexaferrite. The terahertz spectra of complex dielectric permittivity and the spectra of infrared reflectivity were measured at room temperature in the range of 6–7000 cm−1. The obtained broad-band spectra of the real and imaginary parts of permittivity reveal significant changes associated with structural distortions of the (Sr,Ba)O12 anti-cuboctahedron caused by the substitution of Ba2+ with Sr2+ in the same crystallographic positions. [ABSTRACT FROM AUTHOR]

In this work, complex studies of the structure and magnetic properties of SrFe12−xInxO19 powders obtained by the mechanochemical and citrate methods were carried out. The solubility of In in strontium hexaferrite SrFe₁₂O₁₉ at 1200 °C was determined. The structure and properties of the powders were studied using X-ray diffraction analysis, Mössbauer spectroscopy and scanning electron microscopy. Measurements of magnetic properties in magnetic fields up to 1600 kA/m were also performed. Additionally, the hyperthermia effect was investigated. The possibility of controlling the coercivity of the samples in the range from 188.9 kA/m to 22.3 kA/m and saturation magnetization from 63.5 A·m2/kg to 44.2 A·m2/kg with an increase in the degree of In doping was also demonstrated. Investigation of the magnetic hyperthermia of the samples was carried out by temperature measurement with an IR camera when they were introduced into alternating magnetic fields of various frequencies (144, 261 and 508 kHz) and amplitudes (between 11.96 and 19.94 kA/m). According to the study result, there was detected the heating of the SrFe12−xInxO19 sample (x = 1.7). The highest values of magnetic hyperthermia of the sample were observed in a 19.94 kA/m magnetic field and a frequency of 261 kHz. At a concentration of 56.67 g/L, the sample was heated from 23 to 41 °C within 2 min. The parameters SLP (specific loss power) and ILP (intrinsic loss power) were calculated. [ABSTRACT FROM AUTHOR]

Hexagonal ferrites with the formula SrxBa(1−x)Fe12O19 (x = 0; 0.3; 0.5; 0.7; and 1) were prepared using the citrate method. The main feature of this synthesis is a relatively low calcination temperature of 700 °C. An X-ray diffraction study revealed a single-phase material. According to SEM, the particles were 50−70 nm in diameter. The Curie temperature of the samples that were determined using the DSC method varied in a very narrow range of 455−459 °C. Analysis of the magnetic hysteresis loops obtained at 300 K and 50 K indicated all samples as magnetically hard materials in a single-domain state. The maximal magnetic characteristics encompass strontium hexaferrite. The terahertz spectra of complex dielectric permittivity and the spectra of infrared reflectivity were measured at room temperature in the range of 6–7000 cm−1. The obtained broad-band spectra of the real and imaginary parts of permittivity reveal significant changes associated with structural distortions of the (Sr,Ba)O12 anti-cuboctahedron caused by the substitution of Ba2+ with Sr2+ in the same crystallographic positions.

• Dissolution of rare-earth elements (REE) in strontium hexaferrite SrFe 12-x R x O 19 (where R = Er, Tm) obtained by the mechanochemical synthesis was investigated and has value of × = 0.08. • Hexaferrites SrFe 12-x R x O 19 (where R = Er, Tm) doped by REE with the × = 0.08 were obtained by the citrate method. • Colloidal aqueous solutions of strontium hexaferrite nanoparticles doped by REE (Er, Tm) and synthesized by citrate method were obtained by high-energy ball milling (50 h) in octadecene solution with oleic acid. • The dynamic light scattering data show that the volume of the synthesized particles is in the range up to 150 nm, which is suitable for using the synthesized nanoparticles for biomedical applications. • For the first time the hexaferrite SrFe 12-x R x O 19 (where R = Er, Tm) nanoparticles were evaluated as MRI contrast agents. In this work a comprehensive analysis of the structure and properties of doped SrFe 12-x R x O 19 (R = Er, Tm) hexaferrites has been studied. The hexaferrtes were synthesized by two methods: mechanochemical and citrate approaches. The solubility of rare-earth elements (REE) has been studied by precision determination of the lattice spacings and cell volume of the samples, synthesized by mechanochemical method. It has been shown that the solubility of Er and Tm at a temperature of 1200 °C does not exceed × = 0.08 REE ions per formula unit. According to Mössbauer spectroscopy, REE atoms preferentially occupy 12k positions. Nanoparticles of SrFe 12-x R x O 19 (R = Er, Tm) compounds for MRI were obtained by high-energy ball milling of the citrate samples for 50 h in an octadecene solution with oleic acid. Stable hydrosols of nanoparticles were obtained after their coating with Pluronic F127 polymer. It has been shown that the obtained nanoparticles can be used for biomedical applications as contrast agents. [ABSTRACT FROM AUTHOR]

Cerium-based materials were intensively studied in last years because of their high oxygen storage capacity (OSC) associated to the reversible Ce 4+ ↔Ce 3+ process and their properties closely related to the defect chemistry that could be adjusted by adequate selection of dopant. Fe 3+ cation, due to its effective ionic radius smaller than that of Ce 4+ , is an interesting doping agent. In this work we present the synthesis and characterization of Ce (1− x ) Fe x O 2− δ mixed oxides (0≤ x ≤1) synthesized by the so named “citrate method”. Our X-ray diffraction results suggest a rather strong dependence of lattice parameter on nanocrystal size, while Raman spectroscopy evidenced the formation of a small volume fraction of hematite clusters in samples with relatively high iron content, x ≥0.15, not observable in X-ray diffraction experiments. The solid solutions exhibit high porosity and specific surface area, with nearly 10% of pore volume in the micropore size range, making these materials potentially useful for applications in catalysis. [ABSTRACT FROM AUTHOR]

Results are presented of studying electrochemical properties of perovskite-like solid solutions (LaSr)MnTiO ( x = 0-0.25, y = 0-0.03) synthesized using the citrate technique and studied as oxide anodic materials for solid oxide fuel cells (SOFC). X-ray diffraction (XRD) analysis is used to establish that the materials are stable in a wide range of oxygen chemical potential, stable in the presence of 5 ppm HS in the range of intermediate temperatures, and also chemically compatible with the solid electrolyte of LaSrGaMgCoO (LSGMC). It is shown that transition to a reducing atmosphere results in a decrease in electron conductivity that produced a significant effect on the electrochemical activity of porous electrodes. Model cells of planar SOFC on a supporting solid-electrolyte membrane (LSGMC) with anodes based on (LaSr)MnTiO and (LaSr)MnTiO and a cathode of SmSrCoO are manufactured and tested using the voltammetry technique. [ABSTRACT FROM AUTHOR]

In this work, complex studies of the structure and magnetic properties of SrFe 12-x In x O 19 powders obtained by the mechanochemical and citrate methods were carried out. The solubility of In in strontium hexaferrite SrFe₁₂O₁₉ at 1200 °C was determined. The structure and properties of the powders were studied using X-ray diffraction analysis, Mössbauer spectroscopy and scanning electron microscopy. Measurements of magnetic properties in magnetic fields up to 1600 kA/m were also performed. Additionally, the hyperthermia effect was investigated. The possibility of controlling the coercivity of the samples in the range from 188.9 kA/m to 22.3 kA/m and saturation magnetization from 63.5 A·m 2 /kg to 44.2 A·m 2 /kg with an increase in the degree of In doping was also demonstrated. Investigation of the magnetic hyperthermia of the samples was carried out by temperature measurement with an IR camera when they were introduced into alternating magnetic fields of various frequencies (144, 261 and 508 kHz) and amplitudes (between 11.96 and 19.94 kA/m). According to the study result, there was detected the heating of the SrFe 12-x In x O 19 sample (x = 1.7). The highest values of magnetic hyperthermia of the sample were observed in a 19.94 kA/m magnetic field and a frequency of 261 kHz. At a concentration of 56.67 g/L, the sample was heated from 23 to 41 °C within 2 min. The parameters SLP (specific loss power) and ILP (intrinsic loss power) were calculated.

Carbohydrate metabolism in Al-phosphate utilizing cells of carrot [designated as IPG, Koyama et al. (1992) Plant Cell Physiol. 33: 171], which grow normally in Al-phosphate medium accompanied by citrate excretion, was investigated. The excretion of citrate was strongly related to the availability of sucrose in medium, indicating that citrate excretion was severely limited by sucrose in medium. The ratio of the amount of carbon in the excreted citrate to the consumed sucrose, was significantly higher in IPG cells than in wild-type cells. When 50% of the sucrose in the medium was consumed, the ratio was 0.6% for the IPG cells and 0.2% the wild-type cells. Under these conditions, IPG cells showed altered citrate synthesis metabolism, which resulted in increased citrate production. Specific activity of mitochondrial citrate synthase was higher in IPG cells than in wild-type cells, whereas the activity of cytosolic NADP-specific isocitrate dehydrogenase was lower in IPG cells than in wild-type cells. [ABSTRACT FROM AUTHOR]

• Potassium (K) fertilizer improved fruit quality in Cara Cara navel fruit. • K enhanced sugar accumulations by improving sucrose metabolism and sink strength. • K fertilizer increased citrate accumulations partially by promoting its synthesis. Sugars and organic acid are key factors for sensory properties of fruit quality. Potassium (K) is an essential macroelement and is also known as quality element. This study aims to investigate how K affects quality improvement particularly sucrose, fructose, glucose and citrate accumulations in Cara Cara navel orange. K fertilizer increased fruit sucrose, fructose, glucose and citrate concentrations and the ratios of total soluble sugars and citrate, particularly the ratios increased more in the treatment of 0.50 kg/plant K fertilizer. These results showed that suitable amount of K fertilizer could improve fruit quality of Cara Cara navel orange. Further study showed that, at early stage of fruit development, K fertilizer played more important roles in degrading sucrose due to the increased activities of sucrose-degrading enzymes including invertase and sucrose synthase-cleavage activity. Conversely, at late stage of fruit development, K fertilizer played more important roles in re-synthesizing sucrose due to the higher activities of sucrose-synthesizing enzymes including sucrose synthase-synthetic activity and sucrose phosphate synthase. The above results suggested that the upregulations of sucrose-degrading and sucrose-synthesizing enzyme activities caused by K fertilizer were conducive to improving sucrose metabolism and sink strength, and then increased the concentrations of sucrose, fructose and glucose in fruit. K fertilizer increased the activities of citrate-synthesizing enzymes including citrate synthetase and phosphoenolpyruvate carboxylase, but had no significant impacts on the activities of citrate-degrading enzyme, indicating that K fertilizer increased citrate accumulations at least partially by promoting its synthesis. This study finally suggested that K fertilizer improved the accumulations of soluble sugar and citrate in Cara Cara navel orange. [ABSTRACT FROM AUTHOR]