Papers by Keyword: SEM Image

Abstract: In this study, we report a change of morphological distribution for PM2.5 air pollution in Ulaanbaatar. Comparing the measurement results in 2011 and 2017 the concentration of particle size 0.8μm was decreased from 92% to 76.7%. Among winter samples in 2011 it is identified 0.4-0.8μm sized particles covering 48.8% of total, and for samples in 2017 it is 61.7%. This shows that 0.4-0.8 microns of particulate matter predominate in the air pollution caused by solid fuel combustion. The 66.8% of the particles identified <0.8μm sized are in summer samples in 2011. This percentage has increased up to 94.5% in the samples in 2017. It is having been to the most harmful fraction of particulate matters for human health. About particulate shapes distribution, irregular shapes dominated in winter in 2011 and sphere shapes dominated in summer samples. While irregular shapes dominated in the samples in 2017, it was independent of season. This provides on origin of pollution, for example, the summer PM_2.5 pollution is sphere shape from the soil in summer and winter PM_2.5 pollution is irregular from the solid fuel combustion. This is a pilot compared study of PM_2.5 particles in air pollution of Ulaanbaatar.

Abstract: To improve the quality of coconut shell (CS) to use as coarse aggregate different treatment methods are given to CS. Polyvinyl alcohol (PVA) and ferrous sulphate (FS) were used as materials for treating the CS. Ten different types of treatments were considered from raw CS to treat with PVA and FS. Significant reduction of water absorbing quality on CS was found from the different types of treatment given. Scanning electron microscopic (SEM) images were also taken and analyzed. SEM images obtained are exported into the software called ImageJ and analyzed in two different ways: one way is using 8 bits and other way is called RGB. An extract from the ImageJ software is given to support the results of treated CS aggregates. If the CS aggregates are treated, then no doubt that the water absorbing capacity of CS can be reduced.

Abstract: The study investigates the hydrolysis products of lanthanum nitrate, obtained at various pH values and times of the hydrolytic agent addition. It has been found that the structure formation of lanthanum oxyhydroxide is accompanied by capturing the admixture ions, namely, the anions of the reactant salt and carbonate ions. It has been shown that thermal decomposition of the hydrolysis products proceeds in four stages for faster hydrolysis. If hydrolysis is slow, the intervals merge together into three stages of thermal decomposition. The hydrolysis products of lanthanum nitrate, heated up to 500...550 С, actually consist of lanthanum oxide containing nitrate and carbonate, chemically bonded to the oxide matrix, in its inner regions. The composition of the synthesized samples changes if pH varies. The minimal content of admixture ions can be observed at the synthesis pH > 10, if the time of the hydrolytic agent addition equals 24 h. The obtained results suggest that lanthanum nitrate can be used as a precursor for synthesis of structured lanthanum oxide.

Abstract: Modern functional metal oxide materials are based upon the use of nanostructured particles. In recent years materials on the basis of yttrium oxide find ever-widening application. The properties of yttrium oxide depend heavily on precursors and synthesis conditions. One of the poorly investigated precursors is yttrium sulfate. The study discusses the products of alkaline hydrolysis of yttrium sulfate obtained by the sol-gel method. The influence of the synthesis pH on morphological, thermal and structural properties of compounds has been examined. Formation of non-stoichiometric compounds occluding counter-ions of the reactant salts in their structure has been revealed. The nanostructured hydrolysis products are formed, which increase their specific surface at annealing and retain their morphology and sizes. The obtained results give grounds to expect using yttrium sulfate as a precursor for synthesis of structured yttrium oxide.

Abstract: In the paper, the array ordering of the TiO₂ nanotubes obtained by method of the anodic oxidation in different modes in the fluorine-containing aqueous-non-aqueous electrolytes containing glycerin as well as the surface-active reagents is considered. It was shown that such characteristics as the two-dimensional Fourier-spectrum, autocorrelation function and its spectrum allow us to identify the ordering nature and to obtain the preliminary quantitative estimates of SEM order.

Abstract: Porous carbons are disordered materials with applications in many areas such as catalysis, molecular separation, and energy storage/conversion. Among porous materials, active carbons are the most popular materials in separation processes. They are non-crystalline materials with heterogeneous pore structures. This property does not permit accurate structural determinations by diffraction techniques. Thus only limited structural information can be extracted from experimental techniques. Consequently, a molecular model of nanoporous carbon can't be constructed that is based solely on experimental data. Computer simulation techniques provide an alternative way to tackle this problem. So, in this study, the synthesis process of an amorphous active carbon is investigated using molecular dynamics simulation. Simulations are carried out at constant temperature in the box containing specific numbers of pure carbon sheets. Two different types of ensembles have been used for simulation including NPT and NVT. Calculated results show that the final structure of porous carbons is in agreement with SEM images of some commercial active carbons. Also, results indicate that the final structure is consisted of three different pore size (r) zones: r<2 nm which produces micro pores,250 nm which named macro pores. These observations are exactly the same as what is observed in experiments. These various pore sizes especially micro and meso pores are observed in radial distribution function curve, too. At last, the temperature effect on the pore size is investigated. Three different temperatures of 973K, 1073 K and 1173 K are applied for the simulation. Calculated results show that increasing the temperature does not have any significant effects on the pore size and structure.

Abstract: In this paper, CT technique is applied to observe soft soil of different depth , and microstructure characters are analyzed combined with scanning electronic microscope (SEM) and mercury intrusion method. CT images comprehensively reflect the soil microstructure, while every voxel of CT image can be observed with SEM. CT images grey value can reflect the porosity variance, and grey value variance express homogeneity of soil microstructure

Abstract: Transmission electron microscopy (TEM) was used to assess the microstructural changes accompanying semisolid molding of a creep resistant Mg-5%Al-2%Sr alloy. It was revealed that the processing created thixotropic morphologies with globular solids of α-Mg, having well-developed sub-structures. The quickly-solidified liquid fraction, enriched in Al and Sr, led to the formation of increased volumes of a lamellae type Al4Sr phase, surrounding the secondary α-Mg. Traces of Mg17Al12 still existed, predominantly as irregular shape compounds located mainly in grain interiors. Both the primary solid and high melting point precipitates of Mn-Al modified with Sr, acted as nucleation substrates for secondary α-Mg grains.