Scanning Electron Microscope
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2021 ◽  
pp. 1-10
Ellen Hieckmann ◽  
Kaitlin K. K. Kammerlander ◽  
Lydia Köhler ◽  
Laura Neumann ◽  
Stefan Saager ◽  

Algae like diatoms are widely studied as a means to remediate anthropogenically contaminated sites. In the present study, CL (cathodoluminescence) and EDX (energy-dispersive X-ray) spectroscopy in an SEM (scanning electron microscope) were optimized for the detection of Eu(III) sorbed on diatom biosilica. The required stability of biosilica under a focused electron beam was extensively investigated. Using experimentally determined data of thermal properties, the temperature increase within biosilica exposed to an electron beam was simulated by finite element calculations based on results from Monte Carlo simulations of electron scattering. Complementary thermogravimetric studies substantiated a chemical stability of biosilica in a wide temperature range, confirming its suitability for long-lasting SEM investigations. In subsequent EDX measurements, characteristic Eu lines were detected. Eu was found to preferentially accumulate and aggregate on silica fragments. CL spectra were obtained for the Eu(III) reference material, EuCl3. For Eu-loaded biosilica, even parts without detectable Eu signal in the EDX spectra show significant Eu(III) signals in the CL spectra. This highlights the sensitivity of CL in studying f-element sorption. CL data showed that Eu(III) was distributed on the entire surface. In conclusion, this work demonstrates the merit of CL and EDX methods for sorption studies on biogenic materials.

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5288
Xiaoquan Wu ◽  
Daoda Zhang ◽  
Zhi Hu

The microstructural and wear properties of laser-cladding WC/Ni-based layer on Al–Si alloy were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and wear-testing. The results show that, compared with the original specimen, the microhardness and wear resistance of the cladding layer on an Al–Si alloy were remarkably improved, wherein the microhardness of the layer achieved 1100 HV and the average friction coefficient of the layer was barely 0.14. The mainly contributor to such significant improvement was the generation of a WC/Ni-composite layer of Al–Si alloy during laser cladding. Two types of carbides, identified as M7C3 and M23C6, were found in the layer. The wear rate of the layer first increased and then decreased with the increase in load; when the load was 20 N, 60 N and 80 N, the wear rate of layer was1.89 × 10−3 mm3·m−1, 3.73 × 10−3 mm3·m−1 and 2.63 × 10−3 mm3·m−1, respectively, and the average friction coefficient (0.14) was the smallest when the load was 60 N.

2021 ◽  
Vol 40 (2) ◽  
pp. 101-144
Francesco Miniati ◽  
Carlotta Cappelli ◽  
Simonetta Monechi

Abstract. We present a taxonomic revision of the family Fasciculithaceae focused on forms that characterize the early evolution of this family group, which are currently included within the genera Gomphiolithus, Diantholitha, Lithoptychius and Fasciculithus. The investigation approach is based on a combined light microscope (LM) and scanning electron microscope (SEM) analysis of specimens from well-preserved ODP–DSDP site material (ODP Site 1209; Site 1262; ODP Site 1267; DSDP Site 356; DSDP Site 119) and outcrops (Bottaccione and Contessa, Italy; Qreiya, Egypt) across the Danian–Selandian transition. The direct LM–SEM comparison of the same individual specimen provides clarification of several taxa that were previously described only with the LM. One new genus (Tectulithus), five new combinations (Tectulithus janii, Tectulithus merloti, Tectulithus pileatus, Tectulithus stegastos and Tectulithus stonehengei) and six new species are defined (Diantholitha pilula, Diantholitha toquea, Lithoptychius galeottii, Lithoptychius maioranoae, Tectulithus pagodiformis and Fasciculithus realeae). The main characteristics useful to identify fasciculiths with the LM are provided, together with a 3D–2D drawing showing the main structural features. The accurate taxonomic characterization grants the development of an evolutionary lineage that documents a great fasciculith diversification during the late Danian and early Selandian. Four different well-constrained events have been documented: the lowest occurrence (LO) of Gomphiolithus, the paracme of Fasciculithaceae at the top of Chron C27r (PTC27r), the radiation of Diantholitha (LO Diantholitha), the paracme of Fasciculithaceae at the base of Chron C26r (PBC26r), the radiation of Lithoptychius (LO Lithoptychius) and the radiation of Tectulithus (lowest common occurrence of Tectulithus) that shows the biostratigraphic relevance of this group across the Danian–Selandian transition.

Water ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 2511
Corazón G. Morales-Amaya ◽  
María T. Alarcón-Herrera ◽  
Pablo D. Astudillo-Sánchez ◽  
Samuel A. Lozano-Morales ◽  
Liliana Licea-Jiménez ◽  

Arsenic in water is currently a global concern due to the long-term exposure that could affect human health. In this study, magnetic nanoparticles (MNPs), CoFe2O4, and MnFe2O4 were successfully synthesized and applied to remove arsenic (As) from water. The MNPs were characterized using different techniques, such as scanning electron microscope (SEM), Brunauer–Emmet–Teller (BET), and photoelectron spectroscopy (XPS). The nanoscale size and the specific surface area achieved a fast, selective, and high As adsorption capacity. MNPs have a mesoporous structure with a mean pore diameter of 5 nm and a mean particle size of 30 nm. The adsorption capacity of these MNPs was determined through kinetic and equilibrium experiments, multilayer adsorption that obeyed the Freundlich model equation was observed, and the maximum adsorption capacities reached were 250 mg/g for CoFe2O4 and 230 mg/g for MnFe2O4. Furthermore, MNPs characteristics like regeneration and reuse, several pH tolerances, non-ion interference, and effective As removal from groundwater samples confirms the nanomaterials’ potential for future applications in water treatment systems combined with magnetic separation.

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5262
Liping Wu ◽  
Jianguo Zhi ◽  
Jiangshan Zhang ◽  
Bo Zhao ◽  
Qing Liu

The effects of Cerium (Ce) were studied on the casting slab quality, microstructure, and inclusion evolution of cryogenic vessel steel. An optical metallographic microscope, scanning electron microscope, energy dispersive spectrometer, and Thermo-calc thermodynamic software were used for characterization and analysis. The results indicated that the central segregation was significantly improved after adding Ce and reached the lowest level when the content of Ce was 0.0009 wt.%. Meanwhile, the presence of Ce reduces the size of ferrite and improves pearlite morphology. Ce also enables the modification of Al2O3 and MnS + Ti4C2S2 inclusions into ellipsoid CeAlO3 and spherical Ce2O2S + Ti4C2S2 composite inclusions, respectively, which are easier to remove. The formed Ce2O2S inclusions are fine and can work as heterogeneous nucleation points to refine the microstructure of steel.

2021 ◽  
Qingxin Tian ◽  
Jianlong Liu ◽  
Qin Chen ◽  
Mingxiao Zhang

Abstract Objectives: To determine the effect of polyethyleneimine/sodium alginate composite nano-gel (AG/PEI-VX765NGs) coated with VX765 on cardiac function in rats with myocardial infarction (MI). Methods: VX765-polyethyleneimine nano-microspheres (PEI-VX765 NP) were encapsulated by sodium alginate (AG) nanogel (NGs) to construct AG/PEI-VX765 NGs. The morphological observation was performed under scanning electron microscope (SEM). The viability was evaluated by using CCK-8 assay in vitro. Then, 24 male SPF Sprague-Dawley rats were randomly divided into 4 groups: Sham, MI, PEI-VX765NP, and AG/PEI-VX765NGs. After 28 days, rats in each group were subjected to assessment of cardiac function by echocardiography. The myocardial infarct size was evaluated by TTC test, and the differences in cardiac fibrosis and cardiomyocyte apoptosis between groups were analyzed by histological methods. Results: The prepared NGs shows a porous structure, while PEI-VX765 NP is uniformly distributed in the AG NGs samples. AG/PEI-VX765 NGs with a concentration of VX765 (range: 0-1000 μM) displayed no significant toxicity to cells. Meanwhile, we observed a relatively more persistent release of VX765 from AG/PEI-VX765 NGs compared with PEI-VX765. LVIDs and LVIDd in both PEI-VX765 and AG/PEI-VX765NGs groups were significantly smaller than those in MI group, while ejection fraction (EF) and short-axis shortening rate (FS) were markedly increased in the above-mentioned two groups. Compared with MI group, PEI-VX765 and AG/PEI-VX765NGs groups exhibited a significant reduction in the infarct size, degree of fibrosis, and the rate of TUNEL positive cells. Conclusion: AG/PEI-VX765NGs can significantly improve the cardiac function of rats with MI.

2021 ◽  
Vol 27 (3) ◽  
pp. 157-161
Alexander Glotka ◽  
Vadim Ol'shanetskii

In this work, theoretical modeling of the thermodynamic processes of the release of excess phases is carried out, as well as a practical study of the structure and distribution of chemical elements in carbides, depending on alloying using a scanning electron microscope. The obtained dependences were experimentally confirmed using X-ray spectroscopy on nickel-based superalloys. It is recommended to use the obtained mathematical models not only in the design of new nickel-based superalloys, but also in the improvement of known brand compositions within the declared concentrations.

2021 ◽  
pp. 1-12
Zekai Wang ◽  
Feng Gao ◽  
Chengzheng Cai ◽  
Shanjie Su ◽  
Menglin Du

Abstract The thermal stress caused by the ultra-low temperature of liquid nitrogen (LN2) can seriously affect the porosity of the coalbed. In this paper, the effects of various temperature differences on the LN2 damage were studied by changing the initial temperature, so as to explore the effect of LN2 on coal seam with different buried depth. The x-ray diffraction (XRD), scanning electron microscope (SEM), wave velocity, acoustic emission (AE) and uniaxial compression experiments were used in the experiments. The experimental results show that LN2 does do a lot of damage to coal and the LN2 effect increase at first and then decrease with the increase of the initial temperature. When the initial temperature is 293K, before and after liquid nitrogen treatment, the wave velocity damage of the coal sample reaches 0.2207 and the compressive strength decreases by 27.92%. These two values are 0.3697 and 47.37% at the initial temperature of 323K, and 0.2727 and 28.27% at the initial temperature of 353K.. This is because if the temperature exceeds 353 K, it will cause a 3.17% drop in water content, thus reducing the damage caused by LN2, resulting in the overall effect slightly lower than that at 323 K.

2021 ◽  
pp. 3397-3404
Dhamal Sonali

This review concerns the appropriate study of X-ray Photo-electron Spectroscopy to analyze oxidation states in the herbo-mineral drugs. It describes multivalent forms of silver and silver based drugs. Silver exhibits multivalent forms with various phases like AgO, Ag2O and Ag2O3 etc. Silver Bhasma is one of the potent Ayurvedic drug from herbo-metallic combinations. This traditional preparation is used for treating various ailments such as disorders related to eye and nerve, brain functioning and tuberculosis etc. Mixture of silver metal and herbal ingredients passes through Bhasmikarana method and then gets converted into organo-metallic complex i.e. silver Bhasma. The preparation method of Bhasmas aims at removing injurious substances which are foreign to the body from metals. The process of Bhasmikarana transferred the material from its inorganic state to the organic; therefore the assimilation of the substances for their therapeutic use will be easier in the human body. Silver Bhasma plays an essential role in Ayurvedic therapeutics due to its versatile qualities. Therefore, if a Bhasma is to be considered as a standard one, X-ray photoelectron spectroscopy should be one of the essential methods. Scanning electron microscope (SEM) technique was used to detect morphology of silver based Bhasmas and Energy dispersive X-ray spectroscopy (EDAX) detected elemental analysis. X-ray photoelectron spectroscopy is the useful platform to detect important chemical constituents as per their required oxidation states which are essential part in therapeutic use.

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