Iron deficiency is a frequent problem for many crops, particularly in calcareous soils and iron humates are commonly applied in the Mediterranean basin in spite of their lesser efficiency than iron ...synthetic chelates. Development and application of new fertilizers using nanotechnology are one of the potentially effective options of enhancing the iron humates, according to the sustainable agriculture. Particle size, pH, and kinetics constrain the iron humate efficiency. Thus, it is relevant to understand the iron humate mechanism in the plant-soil system linking their particle size, characterization and iron distribution in plant and soil using
Fe as a tracer tool. Three hybrid nanomaterials (F, S, and M) were synthesized as iron-humic nanofertilizers (
Fe-NFs) from leonardite potassium humate and
Fe used in the form of
Fe(NO
)
or
Fe
(SO
)
. They were characterized using Mössbauer spectroscopy, X-ray diffraction (XRD), extended X-ray absorption fine structure spectroscopy (EXAFS), transmission electron microscopy (TEM) and tested for iron availability in a calcareous soil pot experiment carried out under growth chamber conditions. Three doses (35, 75, and 150 μmol pot
) of each iron-humic material were applied to soybean iron deficient plants and their iron nutrition contributions were compared to
FeEDDHA and leonardite potassium humate as control treatments. Ferrihydrite was detected as the main structure of all three
Fe-NFs and the plants tested with iron-humic compounds exhibited continuous long-term statistically reproducible iron uptake and showed high shoot fresh weight. Moreover, the
Fe from the humic nanofertilizers remained available in soil and was detected in soybean pods. The Fe-NFs offers a natural, low cost and environmental option to the traditional iron fertilization in calcareous soils.
The work considers the rotational and translational oscillations of three cylinders differing in terms of the ratio of the length to the cylinder diameter (aspect ratio). The cylinders are suspended ...in the test section of a low velocity wind tunnel on a wire suspension equipped with steel springs. In the equilibrium position, the axis of the cylinders is directed horizontally and parallel to the freestream velocity vector. Under the influence of the air flow, the cylinders can execute rotational or translational oscillations. The two suspension springs are equipped with semiconductor strain gauges that measure the periodically changing tension of the springs during oscillations. The analog signal from the strain gauges is transmitted to a PC oscilloscope, which transmitted it in digital form to a computer. After calibration of the device and decoding of the signal, the frequencies and amplitudes of translational oscillations in the vertical direction and rotational oscillations around the horizontal axis passing through the center of the cylinder and perpendicular to the freestream velocity vector are determined. It turns out that in the studied range of cylinder elongations there is a transition from rotational to translational oscillations. A cylinder with an aspect ratio of 1.9 performs steady rotational oscillations under the influence of wind, and their amplitude increases with increasing air-flow velocity. The previously proposed mathematical model correctly predicts rotational oscillations. The square of the amplitude of rotational oscillations is a linear function of the Strouhal number if the velocity of the air flow is sufficiently large. Translational oscillations of the cylinder with an aspect ratio of 1.9 are damped. A decrease in the aspect ratio of the cylinder down to 1.5 is accompanied by a decrease in the amplitudes of rotational vibrations. At low air-flow velocities, translational oscillations with a small amplitude are registered. Further reducing the aspect ratio to 1.0 eliminates rotational oscillations entirely. The amplitude of translational oscillations increases. Translational oscillations occur in a limited range of air-flow velocities.
—The metallic filter foils of palladium-yttrium alloys are studied using X-ray diffraction analysis. The aim of the research is to study the high-temperature effects on phase transformations in ...palladium-based alloys. The change in the phase composition of the alloy and in its subsystems of defects were found upon the additional annealing of one of the membranes. A decrease in the microstrains was estimated by the change in the diffraction-reflections smearing after the annealing. The formation of regions with an increased lattice parameter in comparison with that of the matrix structure and effects of the high-temperature annealing on the structure of these regions are discussed.
A synthesis route to rock salt zinc oxide (rs-ZnO), high-pressure phase metastable at ambient conditions, has been developed. High-purity bulk nanocrystalline rs-ZnO has been synthesized from ...wurtzite (w) ZnO nanopowders at 7.7 GPa and 770–820 K and, for the first time, recovered at normal conditions. Structure, phase composition, and thermal phase stability of recovered rs-ZnO have been studied by synchrotron X-ray powder diffraction and X-ray absorption spectroscopy (XANES and EXAFS) at ambient pressure. Phase purity of rs-ZnO was achieved by usage of w-ZnO nanoparticles with a narrow size distribution as a pristine material synthesized by various chemical methods. At ambient pressure, rs-ZnO could be stable up to 360 K. The optical properties of rs-ZnO have been studied by conventional cathodoluminescence in high vacuum at room and liquid-nitrogen temperatures. The nanocrystalline rs-ZnO at 300 and 77 K has shown bright blue luminescence at 2.42 and 2.56 eV, respectively.
The study investigated the effect of deformation by high-pressure torsion (HPT) on the hardening, structure transformations, and thermal stability of two eutectic alloys: binary – Al-8.0% Ca and ...complex-alloyed – Al-3.5% Ca-0.9% Mn-0.5% Fe-0.1% Zr-0.1% Sc. The HPT-deformation of the alloys (5 revolutions) led to the formation of a nanocrystalline structure with a high density of crystal defects. A predominant grain size was 20–40 nm in the binary alloy and 11–34 nm in the complex alloy. HPT resulted in the refinement of the Al4Ca particles for the binary alloy and the transformation of the Al4Ca particles into nanoclusters and segregation for the complex alloy. HPT increased the microhardness of the binary alloy to 1.80–2.05 GPa (~2 times), and of the complex-alloyed alloy to 2.40–2.70 GPa (4.1–4.6 times). The hardening of the complex alloy is retained to higher heating temperatures compared to the binary alloy.
Diffusion filtering metallic palladium–yttrium membranes are subjected to hydrogenation from a gas phase and are studied by X-ray diffraction using synchrotron radiation. Boundaries of the formation ...of hydrogen-enriched phases are improved for a range of alloying component content, which is critical for their formation. The effect of the initial state of the alloy on conditions of hydride phase formation in the system is demonstrated. The content of hydrogen occluded in the membrane structure and hydrogen-induced lattice dilatations are determined. The parameters of the alloy substructure are calculated.
The processes of relaxation of the structure, phase composition, and surface topology of the diffusion membrane filters of Pd
0.93
Y
0.07
alloy after hydrogenation are comprehensively studied. The ...difference in the development of defects as a result of their interaction with absorbed hydrogen is shown. The relaxation processes are investigated for the following two cases: the formation of a hydrogen-rich β phase in a membrane during hydrogenation and the presence of an immiscibility region between the dilute solid solution of hydrogen (α phase) and the hydride β phase in the metal alloy. A comparative analysis of changes in the effective size of coherent-scattering regions and microscopic deformations in them at the initial stage of hydrogen retention in the structure of the palladium-based alloy is given. The study of the relaxation features of diffusion filters after hydrogenation reveals significant phase transformations and changes in the substructure parameters of Pd–Y–H systems.
Over the past two decades, LIH SB RAS and BINP SB RAS have jointly conducted experiments on time-resolved (TR) small-angle x-ray scattering (SAXS) with detonating high explosives. The purpose of ...these experiments is to restore the dynamics of carbon species condensation to diamond nanoparticles by analyzing series of SAXS patterns behind the detonation front measured in real time with fast detectors. This knowledge is crucial for the development of reliable detonation models. In this paper, we compare SAXS patterns of identical nanodiamond samples measured at the TR-SAXS extreme state of matter end-station (BINP SB RAS) in the static mode under realistic conditions simulating fast real-time measurements with polychromatic SR beam and traditional SAXS BioMUR beamline at the Kurchatov Synchrotron Radiation Source (NRC "Kurchatov Institute") with monochromatic synchrotron radiation (SR) beam. These experiments confirm that the size of scattering inhomogeneities determined in dynamic experiments with single bunch exposure with polychromatic SR beam is correct.
Electronic structure of the three-dimensional colossal magnetoresistive perovskite La1-xSrxMn03 has been established using soft-x-ray angle-resolved photoemission spectroscopy with its intrinsically ...sharp definition of three-dimensional electron momentum. The experimental results show much weaker polaronic coupling compared to the bilayer manganites and are consistent with the theoretical band structure including the empirical Hubbard parameter U. The experimental Fermi surface unveils the canonical topology of alternating three-dimensional electron spheres and hole cubes, with their shadow contours manifesting the rhombohedral lattice distortion. This picture has been confirmed by one-step photoemission calculations including displacement of the apical oxygen atoms. The rhombohedral distortion is neutral to the Jahn-Teller effect and thus polaronic coupling, but affects the double-exchange electron hopping and thus the colossal magnetoresistance effect.
X-ray diffraction and high-precision scanning electron microscopy methods were used to study the long-term evolution of the defect structure of diffusion filter-membranes Pd-Y. Analysis of X-ray ...diffraction data and microelectronic photographs showed that the recovery of the dislocation structure in the membranes was not uniform. Differences in the processes of hydrogen conservation in the structure of membranes are determined reversible hydrogen doping. Preservation by alloy of superstructural ordered regions was detected.
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