Mössbauer Studies of Narrow Fractions of Fly Ash Formed after Combustion of Ekibastuz Coal

Nuclear gamma-resonance spectroscopy on 57Fe nuclei, X-ray diffraction, and scanning electron microscopy have been used to study the narrow fractions of fly ash formed after combustion of the Ekibastuz coal. Two groups of samples of magnetic (ferrospheres) and non-magnetic type have been separated by granulometric and magnetic separation. A number of regularities associated with the granules size of fly ash have been established. According to the data of Mössbauer spectroscopy, a decrease in the magnetically ordered contribution has been identified with the growth of the particle size. After magnetic separation, iron in ferrospheres was found mainly in the structure of Fe3O4/γ-Fe2O3 and α-Fe2O3. The dominant phase was Fe3O4 (60–77%), the amount of which decreases with the growth of the grain size. With the growth of the particle size, the ratio of [Fe]tetra/[Fe]octa positions occupancy in Fe3O4 approaches 0.5; the structure of magnetite tends to the stoichiometric composition. α-Fe was found in the composition of ferrospheres, and a mechanism of its formation was proposed. The main components of the non-magnetic fractions of fly ash are mullite, hercynite, and silicate glass.

Treatment of Oil from the Oil Industry Wastewater by the Production of a Hydrophobic Magnetic Polymer Nanocomposites

A novel, economic and environment-friendly composite material based on magnetic hollow magnetite (Fe3O4) nanoparticle coated with a polyvinyl pyrrolidone (PVP) was produced to treat the oil from the oil industry wastewaters. The oils were readily removed via hydrophobic PVP -magnetite nanocomposite. In this study the physicochemical properties of the produced PVP-magnetite nanocomposite were investigated with Fourier transform infrared spectrophotometer (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) analysis. The effects of increasing PVP -magnetite nanocomposite concentrations, the effects of separation time, effect of pH on the removal of oil were investigated. The removals of individual oil types with different carbon (C) ring numbers (from C 9 up to C 25) were investigated during oil removal. The reusing capacity of PVP-magnetite nanocomposite was investigated after 40 cycling for oil removal. The removal yields for all pollutants in the oil industry was investigated. FTIR analysis results showed that in the spectrum of PVP-coated magnetite nanocomposite the peak at 2500 1/cm can be attributed to the stretching vibration of C−N and C═O. XRD spectrum of the synthesized PVP– magnetite composite nanoparticle exhibited that the dominant phase of the composite nanoparticle is magnetite with a particle size of 16.8 nm. TGA analysis showed that about 69% weight loss was observed at 500°C and this is attributed to decomposition of PVP. Nonane (9 C rings) and undecane (11 C rings) have high removal yields like 99.99% while the oils with high carbon rings such as, 80% ducosene (22 C rings) and 72% pentacosane (25 C rings) exhibited low yields. The aforementined nanoparticle can be used 29 times to remove the oil with a yield of 99.99%. The maximum CODdis, COD, TSS and oil removal efficiencies were 99%, 99.5%, 99% and 99.90% respectively, via adsorption with 3 mg/l hydrophobic PVP-Fe3O4 / Polimer nanocomposite.

Online quality prediction based on the double cumulative model for multiphase batch processes with transitions

In multiphase batch processes, the final product quality prediction results depend on the common cumulative effects of all the critical phases with transitions on quality rather than a separated one. However, the common cumulative effect are rarely considered at the same time. To address this issue, a double cumulative model is proposed in this paper. The double model includes the internal cumulative model and the external cumulative model. On one hand, the critical local cumulative quality is introduced to isolate the local cumulative effect of different phases and transitions in the internal cumulative model. Especially, for transitions modeling, an average process trajectories method based on the dominant phase identification is developed to deal with the dynamic and uncertainty. On the other hand, the correlation of different cumulative models is extracted by constructing the external cumulative model. In this way, the cumulative effect of all the phases and transitions are considered simultaneously. The proposed method is applied to penicillin fermentation. The simulation results demonstrate the effectiveness and superiority of the proposed method over the competing models.

X-Ray Peak Profile Analysis of Materials M1 and M2 by Williamson-Hall and Size-Strain Plot Methods

In this work, we have studied the Kaolin M1 and M2 by the X-ray diffraction method, and we have focused on mullite phase which is the main phase present in common in both products. An update of the program of the method of Stokes was carried out, it was necessary to the microstructural analysis. The completed version is less sensitive to the choice by excess of the number of coefficients of Fourier with regard to the effect of truncation and the office plurality of the errors. The determination of the symmetry of the cell of the principal phase (mullite) in the studied fritted Kaolins was carried out. In Kaolin M1, the size of crystallites of the dominant phase varies between 80 to 170 Å. In Kaolin M2, the size of the crystalline grains of mullite varies between 100 to 400 Å. The size of crystallites was confirmed by the joint method of Williamson-Hall. A distribution of sizes of crystallites was carried out. It shows a dominance of the size of approximately 140 Å for the principal phase of Kaolin M1 and a dominance of the size of approximately 230 Å for the same principal phase of Kaolin M2. By the study of the profiles of line by DRX, it appears very clearly that the principal phase of the various sintered Kaolins, mullite, is free from internal microstrains. It is the case of the mixtures fritted not only at low temperature (1100℃) during 1 hour but also the case of the mixtures of the type ‘chamotte’ cooks with 1350℃ during very long times.

Analysis of Porous Structure in Autoclaved Materials Modified by Glass Sand

This paper describes the use of glass sand in the production of autoclaved bricks. Traditional autoclaved materials consist of SiO2, CaO, and H2O. The purpose of the tests is to analyze the possibility of using glass sand in autoclaved materials and to determine their properties and durability. Depending on the structure, building materials can have porosities ranging from 0% (glass, metals) to over 90% (thermal insulation materials such as aerated concrete). Porosity of materials is directly related to the strength of materials and their density, and further to the thermal and acoustic insulation properties of products used especially for external wall construction, i.e., bricks, concrete, and aerated concrete. This type of silicate brick is formed at a temperature of 203 °C, therefore the dominant phase forming the microstructure is tobermorite, in contrast to the C-S-H phase, which dominates in concretes and which is characterized by a larger specific surface. The nature of pores, their number, appearance and arrangement in the material can be studied using computer techniques (SEM, XRD, computed tomography, porosimetry). Computed tomography (micro-CT analysis) showed that the number of voids in the material modified by glass sand is about 20% in relation to the weight of the product. The density of the product with glass sand was determined to be 2.2 kg/dm3.

Segmentation and Registration of the Liver in Dynamic Contrast-Enhanced Computed Tomography Images

Dynamic contrast-enhanced computed tomography (DCE-CT) is the main auxiliary diagnostic tool for liver diseases. Liver segmentation and registration in all stages of DCE-CT images are the key technology for big data analysis of liver disease diagnosis. The change of imaging conditions in different stages of DCE-CT brings enormous challenges to the segmentation of liver CT images. This study proposes an automatic model for liver segmentation from abdominal CT images in different stages of DCE on the basis of U-Net. The skip connection in U-Net can improve the ability of complex feature recognition. A total of 4863 CT slices from 16 patients with hepatocellular carcinoma (HCC) were selected as the training set, and 1754 CT slices from 6 patients with HCC were selected as the test set. The training and test sets included plain scan, hepatic arterial-dominant phase, and portal venous-dominant phase CT scans. Results showed that the Dice value of the proposed method was significantly higher than those of the full convolutional network and region-growing method. Then, 3D reconstruction and registration were performed on the segmentation results of the liver region of DCE-CT images. The proposed method obtained the best performance, which can provide technical support for the big data analysis of liver diseases.

Direct synthesis of nanostructured silver antimony sulfide powders from metal xanthate precursors

Silver(I) ethylxanthate [AgS2COEt] (1) and antimony(III) ethylxanthate [Sb(S2COEt)3] (2) have been synthesised, characterised and used as precursors for the preparation of AgSbS2 powders and thin films using a solvent-free melt method and spin coating technique, respectively. The as-synthesized AgSbS2 powders were characterized by powder X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. The crystalline AgSbS2 powder was investigated using XRD, which shows that AgSbS2 has cuboargyrite as the dominant phase, which was also confirmed by Raman spectroscopy. SEM was also used to study the morphology of the resulting material which is potentially nanostructured. EDX spectra gives a clear indication of the presence of silver (Ag), antimony (Sb) and sulfur (S) in material, suggesting that decomposition is clean and produces high quality AgSbS2 crystalline powder, which is consistent with the XRD and Raman data. Electronic properties of AgSbS2 thin films deposited by spin coating show a p-type conductivity with measured carrier mobility of 81 cm2 V−1 s−1 and carrier concentration of 1.9 × 1015 cm−3. The findings of this study reveal a new bottom-up route to these compounds, which have potential application as absorber layers in solar cells.

A Small Number of Gametophytes with Gametangia and Stunted Sporophytes of Antrophyum obovatum Baker (Pteridaceae): The Suppression of Functional Sporophyte Production by Prezygotic and Postzygotic Sterility

Ferns have conspicuous sporophytes as the dominant phase in their life cycle; however, the gametophytes are completely separated from the sporophytes and supply their own nutrition, unlike in bryophytes and seed plants. Among the gametophytes, some maintain their populations in the gametophyte phase without progressing to sporophyte production and are known as independent gametophytes. Independent gametophytes of Antrophyum obovatum Baker were recently reported in one population on Jeju Island, Korea. In the present study, we surveyed more places to find new independent gametophyte populations of A. obovatum using the rbcL gene sequence-based DNA barcoding technique. We identified two new sites inhabited by independent gametophytes. Archegonia and juvenile sporophytes were independently observed in each location under slightly different environmental conditions. Consequently, in the case of this species, functional sporophyte production is likely suppressed by prezygotic and postzygotic sterility, depending on microenvironmental factors.

Soils and sediments of Prošće Lake catchment as a possible terrigenous input in the lakes system

The Plitvice Lakes National Park is in the northwestern part of the Dinaric Karst in central Croatia. An important role of the soil in the karst is to purify the waters before they reach the phreatic zone. The soil is also a zone of accumulation, transformation, retardation and dilution of a potential pollutant. Knowing soil mineralogical composition is an important factor in understanding fate and transport of contaminants throughout lakes system. Samples of soil, peat and stream sediment were collected in the Prošće lake catchment and partly in the assumed zone of influence, X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR) analysis of samples was performed to determine dominant mineral species in samples. XRD analysis showed predominance of lowquartz, which was found in all samples, most often as dominant phase. Dolomite was found in half of the samples, almost always as a significant phase while calcite was dominant phase in one of the samples. In most of the samples, members of the feldspars and chlorites groups, as well as muscovite, were present as minor phases. The absorption bands in the range of 2800-3000 cm-1 due to the organic matter are visible in spectra of all samples. These minerals can enter lakes system by surface waters, primarily streams and overland flow during snow thawing and rain, and also in cases of shore erosion. Terrigenic input in lakes is small but cannot be neglected due to the longlasting preservation efforts of the Prošće Lake recharge area, and the Plitvice Lakes National Park in general, terrigenous intake still does not pose a threat to water quality and tufa production. Considering the analyzed samples and characteristics of detected soil constituents, soils and sediments in the Prošće Lake catchment have the ability to retain and purify water on its way to the lakes. On the other hand, in case of the possible contamination in the recharge area of the lakes system, the pollutants can enter the system adsorbed on the soil particles. Learning more about the soils surrounding lakes gives valuable insight into their possible influence on lakes water chemistry and adds one piece of the puzzle into understanding this kind of a natural phenomenon.

Performance of full-cell Na-ion with NaNi1/3Mn1/3Co1/3O2 cathode material and different carbonate-based electrolytes

The battery performance not only depend on the electrodes nature but also depend on the choice of electrolyte consisting of salts and organic solvents. The development of electrolytes compatible with both cathode and anode materials is essential for enhancing the performance of practical full-cell Na-ion batteries. Among electrode with difference Ni/Mn/Co ratio, NaNi1/3Mn1/3Co1/3O2 (NMC) showed the best stable cycling. Besides, carbonaceous anode materials such as hard carbon (HC) are attracting due to it low cost, high gravity/volumetric capacity. In this work, the electrochemical performance of full-cell Na-ion including NMC as cathode and HC as anode was studied in difference carbonate-based electrolytes with 2wt%FEC as additive. The cathode material was synthesized by sol-gel reaction following a calcination at 900oC for 12 hours. X-ray diffraction result of the synthesized sample indicates a layered structure with mutual O3 and P2 phase intergrowth and the dominant phase is O3. The impurity phase NiO also presents with negligeable content. In half-cell configuration with sodium metal anode, the material exhibited a typical staircase chargedischarge profile in various electrolytes. The highest capacity of 106 mAh/g with stable clycing up to 50 cycles was obtained in the electrolyte NaClO4 1 M/PC+2wt%FEC. However, this electrolyte couldn't enable the cycling the full-cell HC||NMC due to the incompatibility with HC anode. In consequence, the initial capacity of full-cell in this electrolyte was only 30 mAh/g and significantly decreased in consecutive cycles. Meanwhile, the electrolytes without PC or with low PC content tend to improve the charge/discharge capacity and the cycle life as well. Indeed, full-cell HC||NMC using NaClO4 1M/EC-DMC (1:1) + 2wt%FEC electrolyte exhibited the highest capacity of 90 mAh/g and excellent capacity retention (90% of the initial capacity) after 50 cycles. Additionally, the full-cell could deliver capacity of 55 mAh/g at high rate up to 2C.