Decomposition Of Solution Research Articles

Canfieldite Ag8SnS6 nanoparticles with high light absorption coefficient and quantum yield

Canfieldite Ag8SnS6 (STS) nanocubes were prepared by the solution decomposition of precursors using heat-up and hot injection protocols employing coordinating solvents (oleylamine - OLA and dodecanethiol - DT) to afford monodispersed silver tin sulfide (STS) nanoparticles. The phase and shape of nanoparticles were tuned by varying reactants' temperature and mole ratios. The powder X-ray diffraction (p-XRD) and transmission electron microscopy (TEM) analysis indicate phase pure orthorhombic Ag8SnS6 nanocrystals with nearly monodispersed particles ranging between 12 and 50 nm. The p-XRD patterns for the STS nanoparticles obtained by the heat-up method exhibited enhanced peak broadening than the hot injection route, accounting for the corresponding quantum confinement effects. Likewise, the (124), (227) and (266) planes of the reflections in OLA/DT capped STS crystals appeared well resolved, indicating that seed growth of a transitional Ag2S might be involved in the formation of the ternary chalcogenides. The values of the energy bandgap (Eg) were found in the range of 1.16–2.60 eV. At the same time, the STS nanoparticles exhibited high photon absorption and low quantum yield potentials, making them a possible candidate for photovoltaic cells and enhanced photoelectrochemical performance.

Carbon dioxide emission and its impacting factor from goldenrod (Solidago canadensis) and bulrush (Typha angustifolia) decomposition during the winter period

Leaf litter decomposition in solution is an important part of the carbon cycle. When leaf litter is deposited in water, the decomposition process takes place, releasing carbon dioxide into the atmosphere. In Hungary, the goldenrod and bulrush are spreading over increasing areas along lakes and rivers, including the shores of Lake Balaton. The primary role of the Kis-Balaton wetland is to retain inorganic nutrients, thereby improving the water quality of Lake Balaton. As the water movement in this area is not very intensive and the water retention time is long, carbon dioxide emissions of parts of decomposing plants can be higher in this area. We set up a microcosm experiment in a climate chamber to determine the carbon dioxide emissions from the decomposition of goldenrod and bulrush leaves and stems in winter when information about the process is limited. Due to short investigation time, the difference in the impact of temperatures on decomposition of the studied plants was restricted to leaves only. In the study, significant difference was obtained for the plant species and the plant parts. The carbon dioxide increments ranged from 46.7 (p<0.001) to 54.5% (p<0.001) in every plant treatment related to control one. Changes in water temperature are reflected in carbon dioxide release with a minor time delay. The results showed that the decomposition of plant parts in water during winter contributes to the increase of carbon dioxide emissions from shallow water bodies, such as the Kis-Balaton wetland.

Effect of low-temperature quasihydroextrusion on the structure and physical properties of CuCrZr alloy

The work is devoted to the study of changes in the structural and physical properties of the precipitation-hardened CuCrZr alloy under the influence of low-temperature (77 K) quasihydroextrusion with various degrees of deformation at liquid nitrogen temperature with subsequent aging. Prior to quasihydroextrusion, commercial alloy samples were annealed and quenched from the premelting temperature to obtain a supersaturated solid solution of alloying elements in the copper matrix. After quasihydroextrusion, the microstructure, lattice constant, pole densities, tensile strength and yield strength, microhardness (in different cross-sections of the extrudate), and electrical conductivity of the CuCrZr alloy were studied depending on the degree of deformation by quasihydroextrusion. It is shown that the deformation degree determines the kinetics of decomposition of the supersaturated solid solution and its structure. As a result of extrusion, an anisotropic structure of the matrix and precipitates is formed, which also determines the anisotropy of material properties. Subsequent aging leads to a significant decrease in the anisotropy of properties. With an increase in the deformation degree during extrusion (before aging), a significant monotonous increase in physical and mechanical properties occurs. However, in the range of deformation degrees of 40–50%, an anomalous “jump” of all measured properties and structural parameters is observed. The study proposes a physical mechanism that explains the experimental results. The mechanism is based on the occurrence of two kinetically differently directed processes: dynamic aging and its inhibition due to an increase in the defectiveness of the material. The latter process manifests itself essentially at low temperatures. In general, low-temperature quasihydroextrusion makes it possible to obtain a complex of sufficiently high mechanical and electrical characteristics of the CuCrZr alloy at relatively low degrees of deformation for one extrusion cycle, which is facilitated by low deformation temperature.

Enhancement Mechanism of Chemical Mechanical Polishing for GaN Based on Electro-Fenton Reaction

In order to obtain a high material removal rate (MRR) with good surface quality, the electro-Fenton reaction was used to assist the chemical mechanical polishing (CMP) for the gallium nitride (GaN) substrate. The fluorospectrophotometry, potentiodynamic polarization method and X-ray photoelectron spectroscopy (XPS) were applied to analyze the enhancement mechanism of the CMP of GaN assisted by electro-Fenton reaction. The results revealed that the hydroxyl radical (·OH) concentration in the electro-Fenton solution increased by 41.75%, and the corrosion potential decreased by 24.67% compared with the Fenton solution, which proved that the electro-Fenton solution had strong corrosion characteristics and the gallium oxide (Ga2O3) formation rate on the wafer surface was accelerated. A high MRR of 274.45 nm h−1 with surface roughness (Ra) of 0.88 nm was obtained by electro-Fenton solution. The reduction reaction of the electric field increased the conversion rate of ferrous ions (Fe2+) and ferric ions (Fe3+) effectively and promoted the decomposition of the H2O2 solution. Meanwhile, the oxidation reaction on the GaN wafer surface was enhanced, and high processing efficiency was achieved. Furthermore, the electric field generated a small amount of H2O2, which increased the ·OH concentration and improved the oxidation characteristics of the solution.

Substitution limits and thermodynamic stability of solid solutions in HTSC based on iron and yttrium oxyarsenides

The mixing energies (interaction parameters) and the critical decomposition (stability) temperatures of Y1–xLnxFeAsO0.6 solid solutions, where Ln = La–Er, 0 &amp;lt; x &amp;lt; 1.0, were determined within the framework of the V. S. Urusov crystal-energetic approach in the approximation of regular solid solutions. Diagram of thermodynamic stability and domes of the solid solution decomposition have been plotted, which make it possible to calculate the equilibrium isomorphous substitution limits of yttrium for rare earth elements x depending on the decomposition temperature Td, or the decomposition temperature depending on the substitution limit. The results of calculation do not contradict to the experimental data found earlier in the literature for La1–xYxFeAsO0.6 and related systems La1–yYvFeAsO, La0.8Y0.2FeAsO0.7, and Y0.95La0.05FeAsO1–vH0.15. The results of this work can be useful in choosing the components’ ratio in “mixed” matrices and the dopant content in high-temperature superconductors, effective magnetic and other materials.

An In-Situ Fabrication Method of ZnO and Other Zn(II) Compounds Containing Polypropylene Composites.

This study investigated the methods of preparation of zinc oxide-polypropylene nanocomposites and their antibacterial properties. Seven solutions with ZnO nanoparticles or zinc ions were formulated as a PP additive. Two methods of ZnO NPs syntheses were carried out: (1) a modified hydrothermal method where a water solution of zinc acetate dihydrate, PEI, and ammonia were mixed with a final pH 11; (2) a thermal decomposition of a water solution of zinc acetate in the presence of PEI and ammonia using a two-screw extruder. During the experiments, the influence of various amounts of particle stabilizer, heating of the solutions, and the temperatures of the syntheses were examined. As a result, the simultaneous crystallization of ZnO in the extrusion process confirmed this method's attractiveness from the application point of view. Fabricated PP-ZnO composite shows antibacterial properties against Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae.

Decreasing the W-Cr solid solution decomposition rate: Theory, modelling and experimental verification

Tungsten-based alloys are essential materials in the nuclear fusion reactors’ development. Particularly, tungsten-chromium single solid solution is interesting for the combination of a good oxidation behaviour and lack of lower-melting-point phases. The W-Cr system has a miscibility gap though and the solid solution within the particular condition is inherently metastable/unstable and tends to decompose forming a Cr-rich phase. In this study, we have combined computer simulations and experimental work to find additional alloying elements to promote the stability of W-Cr solid solution. The results showed that alloying with Ta may result in lowering the stabilising temperature of the alloy, positively affecting the decomposition rate. Experiments performed on a W-Cr-Ta alloy showed prolonged solid solution lifetime when compared to W-Cr alloy. Formation of the third decomposed phase, enriched in Ta, was observed and changes in the chromium diffusion in the alloy were identified to be the governing factor for slowing down the decomposition.

Nonlinear computer image scene and target information extraction based on big data technology

Abstract To explore the extraction of computer image scene and target information, a nonlinear method based on big data technology is proposed. The method can decompose the computer image into a plurality of components when the SAR computer image is processed such as target extraction and computer image compression, which represent different captured image features, respectively. Selecting the most suitable processing method according to the characteristics of different components can greatly improve the performance. Using nonlinear diffusion method, the computer image is decomposed into structural components representing large-scale structural information and texture components representing small-scale detailed information, and the automatic threshold estimation in the diffusion process is studied. The LAIDA criterion is introduced into the automatic threshold solution of nonlinear diffusion-based computer image decomposition to test and evaluate the diffusion process of various diffusion parameter forms. The results show that the experimental outcome of the diffusion decomposition based on automatic threshold estimation is very close on each index, which shows that using automatic threshold estimation, no matter what diffusion index is used, very close results can be obtained. Specifically, for each algorithm, the parameter estimation threshold l for outliers plays an obvious role. The third is the degree of initiative of the estimation process. The larger the L, the larger the outlier, which will lead to a greater extent of the diffusion process, resulting in a continuous decrease in the structural similarity index and compositional correlation. It is proved that the algorithm has strong global search ability, can effectively avoid premature convergence, has fast convergence speed, and good long stability. It can be widely used for optimization of various multimodal functions.

Numerical analysis of a singularly perturbed convection diffusion problem with shift in space

We consider a singularly perturbed convection-diffusion problem that has in addition a shift term. We show a solution decomposition using asymptotic expansions and a stability result. Based upon this we provide a numerical analysis of high order finite element method on layer adapted meshes. We also apply a new idea of using a coarser mesh in places where weak layers appear. Numerical experiments confirm our theoretical results.

Role of the synthesis procedure on the physicochemical properties of doped magnetite

The studies presented in this paper show the results of synthesis and physicochemical characterization of modified ferrite nanoparticles, which can be described by the general formula MxFe3-xO4 (where x = 0.15 or 0.45) doped with Al3+, Cr3+, Cu2+ and Zn2+ ions. The nanoparticles were obtained through procedures using either water or organic environment. The aim of this study was to determine the influence of synthetic routine and doping on the quality of the obtained structure, morphology and magnetic properties of nanoparticles. Additionally, doping concentration of selected elements is a crucial influence on the crystallinity and magnetic properties of the obtained nanoparticles. Doped nanoparticles were synthesized by two chemical methods: co-precipitation of iron chlorides in a basic solution and thermal decomposition of iron(III) acetylacetonate in an organic high-boiling solvent. Obtained nanoparticles were characterized by transmission electron microscopy, energy dispersive X-ray, X-ray diffraction, porosimetry, infrared spectroscopy and Mössbauer spectroscopy.

Identity-Based Unidirectional Collusion-Resistant Proxy Re-Encryption from U-LWE

Identity-based proxy re-encryption (IB-PRE) converts the ciphertext encrypted under the delegator’s identity to the one encrypted under the delegatee’s identity through a semitrusted proxy without leaking delegator’s private key and the underlying plaintext. At present, the security of most IB-PRE schemes relies on the hardness of the discrete logarithm solution or large integer decomposition and cannot resist attacks of the quantum algorithms. The majority of the IB-PRE schemes over lattice are secure only in the random oracle model. Aiming at such problems, the paper constructs a secure IB-PRE scheme over lattice in the standard model. In the scheme, the underlying encryption scheme proposed by Gentry et al. in EUROCRYPT 2010 is adopted to reduce the storage space of ciphertext. The proposed scheme is unidirectional collusion-resistant multihop and anonymous, and it is semantically secure against selective identity and chosen plaintext attack based on Decisional Learning With Errors with uniformly distributed errors (D-U-LWE) hard problem in the standard model.

Problems in Imaging the Decomposition of Liquid and Solid Solutions in the Ag–Cu–Ni and Ag–Cu–Pb Systems

Problems in Imaging the Decomposition of Liquid and Solid Solutions in the Ag–Cu–Ni and Ag–Cu–Pb Systems

Фотокаталитическое разложение растворов метилового оранжевого на поверхности нанопористых слоев меди, серебра и их йодидов

The efficiency of photocatalytic decomposition of methyl orange solutions on the surface of nanoporous layers of copper, silver and their iodides has been studied. It is shows that nanoporous layers on metal substrates have two absorption bands: they absorb radiation in the UV and Vis spectral range. The process of decomposition of methyl orange molecules on the surface of metal-semiconductor nanostructures Cu-CuI and Ag-AgI occurs under the action of UV and Vis irradiation. While transparency of the methyl orange solution increases.

Problems in Imaging the Decomposition of Liquid and Solid Solutions in the Ag–Cu–Ni and Ag–Cu–Pb Systems

Three-dimensional (3D) computer models of Ag–Cu–Ni and Ag–Cu–Pb isobaric phase diagrams, designed based on 23 and 31 base points, respectively, assembled from 14 and 32 surfaces, 9 and 15 phase fields, respectively, and intended to digitize information on these diagrams, are used to verify the adequacy of interpretation of published isothermal and polythermal sections, both calculated and experimentally studied ones. The geometric features of the phase diagram regions that relate to liquid–liquid miscibility gaps and solid solution decomposition are refined in the 3D models. Mistakes arising from an incorrect imaging of the decay of copper–nickel solid solutions and from discrepancies in the values of the Ag–Cu–Pb ternary eutectic temperature are shown on polythermal sections.

Asymptotic behavior for wave equations with space-dependent damping in a weighted energy class

In this paper, we discuss diffusion phenomena for the wave equation with space-dependent damping. It is known that this phenomenon occurs in the constant damping case with initial data belonging to a suitable energy class. This paper clarifies that diffusion phenomenon also occurs when the damping is effective and space-dependent, and initial data belong to a certain energy class. The proof relies on an energy method involving Kummer's confluent hypergeometric functions with a modified version of the technique of decomposition of solutions introduced in [20].

ВЛИЯНИЕ ТЕРМИЧЕСКОЙ ОБРАБОТКИ НА СПЛАВЫ СИСТЕМЫ Al‒Mg‒SiС ИЗБЫТКОМ КРЕМНИЯ И МАЛЫМИ ЦИРКОНИЕВЫМИ ДОБАВКАМИ

The study is aimed at studying heat treatment for the formation of physical and mechanical properties in the Al-Mg-Si system with an excess of silicon and small zirconium additives. The study was carried out on the example of three alloys with different Mg/Si ratios with a zirconium content of 0.15%. The alloys were subjected to both one and two-stage heat treatment. In the course of a single-stage heat treatment, the alloys were annealed at a temperature of 375–550 °C and holding, which ranged from 10 seconds to 100 hours, followed by fixation of the microstructure in water. In addition, a multi-stage heat treatment was carried out, the annealing temperature of the first stage was varied in the range of 425–550 °C with an 8-hour exposure and subsequent fixation in water, after which the metal was subjected to a 3-hour artificial aging. After completion of the heat treatment, the microhardness and electrical conductivity were investigated. Based on the data on the change in the latter depending on the mode of heat treatment, C-curves of the decomposition of the supersaturated solid solution were constructed. For some modes of heat treatment, studies of intermetallic particles were carried out using scanning microscopy. Using scanning electron microscopy, particles were found in the alloys, similar in their chemical composition to Mg2Si, Al3(FeSi) and Zr2Si. The obtained C-curves show that the decomposition of a supersaturated solid solution begins already at a temperature of 375 °C. Using the constructed C-curves, the influence of the content of silicon, magnesium elements on the rate of decomposition of a supersaturated solid solution is shown. It has been established that the annealing temperature of 375 and 425°C adversely affects the microhardness in the alloys under consideration. After an increase in the annealing temperature to 550°C, there is practically no decrease in microhardness. The performed studies made it possible to choose the optimal mode of multi-stage heat treatment, namely heating to 550 °C for 8 hours with cooling in water, and subsequent 3-hour exposure at a temperature of 180 °C. In general, zirconium additives give an increase in microhardness by 11-25 HV compared to base alloys.

Зменшення схильності висококремнистих сплавів Al−Mg−Si(Cu) до міжкристалітної корозії

The mechanical properties and susceptibility to intergranular corrosion (IGC) of Al-Mg-Si(Cu) aircraft alloys containing 1.4-1.5%Si were studied. A different Mg/Si ratio and a different phase content of Mg2Si and Si, as a consequence, were realized for them by varying the chemical composition. It is shown, that the strength of the alloys increases and the resistance to MGC decreases as the chemical composition of the alloy moves away from the quasi-binary cross-section and the amount of residual silicon Si+ above the limit required for Mg2Si formation is enhanced. Marked No. 2 the strongest alloy and the least corrosion-resistant, at the same time, which has UTS ≥350 MPa and MGC penetration depth of more than 100 μm was determined. It contains 0.7 % Si+ and, among the other experimental alloys, this one is the closest to the upper solubility limit of 1.85 % Mg2Si in aluminum. The negative effect of Cu and Fe on MGC, as well as the temporary delay, if any between quenching and strengthening heat treatment (artificial aging), was demonstrated. A series of isothermal curves, which characterize the strengthening of alloy No. 2 during artificial aging, was obtained, and it is shown, there is no isothermal processing within the temperature range of 145-200 °С, which would increase its resistance to MGC. Analyzing the generally accepted sequence of phase transformations, which takes place during the decomposition of a supersaturated solid solution after quenching, two-stage treatment modes of 145 °С, 4 h + 220 °С, 0.5 h and 145 °С, 2 h + 165 °С, 4 h were found and tested. They provided decreasing the maximum depth of MGC penetration by approximately 1.5-2.5 without significant worsening of the mechanical properties for alloy No. 2. Keywords: aircraft alloys, strength, intergranular corrosion, residual silicon, artificial aging, multi-stage processing.

The Catalytic Performance of CO Oxidation over MnOx-ZrO2 Catalysts: The Role of Synthetic Routes

MnOx-ZrO2 catalysts prepared by co-precipitation and vacuum impregnation were calcined at 400–800 °C and characterized by powder X-ray diffraction, textural studies, high-resolution transmission electron microscopy, temperature-programmed reduction, X-ray absorption near edge structure, and X-ray photoelectron spectroscopy. The catalytic activity was tested in the CO oxidation reaction. The activity of the co-precipitated samples exceeds that of the catalysts prepared by vacuum impregnation. The characterization studies showed that the nature of the active component for the catalysts obtained by co-precipitation differs from that of the catalysts obtained by impregnation. In the impregnation series, the most active catalyst was obtained at a temperature of 400 °C; its increased activity is due to the formation of MnO2 oxide nanoparticles containing Mn4+ and low-temperature reducibility. An increase in the synthesis temperature leads to the formation of less active Mn2O3, catalyst sintering, and, accordingly, deterioration of the catalytic properties. In the case of co-precipitation, the most active CO oxidation catalysts are formed by calcination at 650–700 °C in air. In this temperature interval, on the one hand, a MnyZr1−yO2−x solid solution is formed, and on the other hand, a partial separation of mixed oxide begins with the formation of highly dispersed and active MnOx. A further increase in temperature to 800 °C leads to complete decomposition of the solid solution, the release of manganese cations into Mn3O4, and a drop in catalytic activity.

Convergence problem of Schrödinger equation and wave equation in low regularity spaces

This paper is devoted to investigating the convergence problem of the nonlinear Schrödinger equation and the nonlinear wave equation. Firstly, the almost everywhere pointwise convergence of the one-dimensional nonlinear Schrödinger equation is established in Hs(R)(s≥14) with the aid of the decomposition of integral form solution to problem. Secondly, the uniform convergencelimt→0⁡supx∈R⁡|u(x,t)−S1(t)f|=0 is established with initial data in Hs(R)(s>0), where u is the solution to the one-dimensional nonlinear Schrödinger equation and S1(t)f is the solution to the free one-dimensional Schrödinger equation. Finally, the almost everywhere pointwise convergence of the nonlinear wave equation is established in Hs(R3)(s>1).

Photocatalytic degradation of reactive brilliant blue KN-R by Ti-doped Bi2O3.

In this study, different compositions of Ti-doped Bi2O3 photocatalytic materials were prepared by chemical solution decomposition method. It was used to degrade reactive brilliant blue KN-R, and then characterized by XRD, SEM, UV-vis DRS, XPS, photocurrent, and other detection methods. The results show that when the catalyst dosage is 1.0g/L and the initial concentration of reactive brilliant blue KN-R is 20mg/L, the degradation rate of pure Bi2O3 to reactive brilliant blue KN-R is 75.30%; the Ti doping amount is 4% (4Ti/Bi2O3), 4Ti/Bi2O3 had the best degradation effect on reactive brilliant blue KN-R, and the degradation rate could reach 93.27%. When 4Ti/Bi2O3 was reused for 4 times, the degradation rate of reactive brilliant blue KN-R only decreased by 6.91%. Doping Ti can inhibit the growth of Bi2O3 grains, making the XRD peak of Ti/Bi2O3 material wider. The pure Bi2O3 particles are larger and the surface is smooth. With the increase of Ti doping content, the surface of Ti/Bi2O3 material grows from roughness to nanofibrous Bi4Ti3O12. The visible light absorption performance and electron separation and transfer ability of Bi2O3 are significantly improved by doping Ti ions. The band gap is reduced from 2.81 to 2.75eV. In conclusion, doping Ti enhances the visible light absorption and electron separation and transfer capabilities of Bi2O3, reduces the band gap, and improves the surface morphology, which makes Bi2O3 have higher photocatalytic performance.