Scanning Electron Microscopy Equipped With Energy Dispersive Spectroscopy Research Articles

Mesoporous silica nanoparticles enhance seedling growth and photosynthesis in wheat and lupin

The application of mesoporous silica nanoparticles (MSNs) as a smart delivery system to agricultural crops is gaining attention but the release of nanoparticles into the environment may pose a potential threat to biological systems. We investigated the effects of MSNs on the growth and development of wheat and lupin plants grown under controlled conditions. We report a dramatic increase in the growth of wheat and lupin plants exposed to MSNs. We also found that, in leaves, MSNs localised to chloroplasts and that photosynthetic activity was significantly increased. In addition, absorption and cellular distribution of MSNs by the two plant species following root uptake were observed using scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS). Following uptake of MSNs at 500 and 1000 mg L−1, there was enhancement of seed germination, increased plant biomass, total protein and chlorophyll content. Treatment of both species with MSNs at the highest concentration (2000 mg L−1) did not result in oxidative stress or cell membrane damage. These findings show that MSNs can be used as novel delivery systems in plants and that over the range of concentrations tested, MSNs do not have any negative impacts on plant growth or development.

Formation of Microbial Mats and Salt in Radioactive Paddy Soils in Fukushima, Japan

Coastal areas in Minami-soma City, Fukushima, Japan, were seriously damaged by radioactive contamination from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident that caused multiple pollution by tsunami and radionuclide exposure, after the Great East Japan Earthquake, on 11 March 2011. Some areas will remain no-go zones because radiation levels remain high. In Minami-soma, only 26 percent of decontamination work had been finished by the end of July in 2015. Here, we report the characterization of microbial mats and salt found on flooded paddy fields at Karasuzaki, Minami-soma City, Fukushima Prefecture, Japan which have been heavily contaminated by radionuclides, especially by Cs (134Cs, 137Cs), 40K, Sr (89Sr, 90Sr), and 91 or 95Zr even though it is more than 30 km north of the FDNPP. We document the mineralogy, the chemistry, and the micro-morphology, using a combination of micro techniques. The microbial mats were found to consist of diatoms with mineralized halite and gypsum by using X-ray diffraction (XRD). Particular elements concentrated in microbial mats were detected using scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS) and X-ray fluorescence (XRF). The objective of this contribution is to illustrate the ability of various diatoms associated with minerals and microorganisms which are capable of absorbing both radionuclides and stable isotopes from polluted paddy soils in extreme conditions. Ge semiconductor analysis of the microbial mats detected 134Cs, 137Cs, and 40K without 131I in 2012 and in 2013. Quantitative analysis associated with the elemental content maps by SEM-EDS indicated the possibility of absorption of radionuclide and stable isotope elements from polluted paddy soils in Fukushima Prefecture. In addition, radionuclides were detected in solar salts made of contaminated sea water collected from the Karasuzaki ocean bath, Minami-soma, Fukushima in 2015, showing high Zr content associated with 137Cs and 40K without 131I. The results obtained here provide evidence of the ability of microorganisms to grow in this salty contaminated environment and to immobilize radionuclides. It is possible that the capability of radioactive immobilization can be used to counteract the disastrous effects of radionuclide-polluted paddy soils.

Transformation and Immobilization of Chromium by Arbuscular Mycorrhizal Fungi as Revealed by SEM-EDS, TEM-EDS, and XAFS.

Arbuscular mycorrhizal fungi (AMF), ubiquitous soil fungi that form symbiotic relationships with the majority of terrestrial plants, are known to play an important role in plant tolerance to chromium (Cr) contamination. However, the underlying mechanisms, especially the direct influences of AMF on the translocation and transformation of Cr in the soil-plant continuum, are still unresolved. In a two-compartment root-organ cultivation system, the extraradical mycelium (ERM) of mycorrhizal roots was treated with 0.05 mmol L(-1) Cr(VI) for 12 days to investigate the uptake, translocation, and transformation of Cr(VI) by AMF using inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy equipped with energy-dispersive spectroscopy (SEM-EDS), transmission electron microscopy equipped with energy-dispersive spectroscopy (TEM-EDS), and X-ray-absorption fine structure (XAFS) technologies. The results indicated that AMF can immobilize quantities of Cr via reduction of Cr(VI) to Cr(III), forming Cr(III)-phosphate analogues, likely on the fungal surface. Besides this, we also confirmed that the extraradical mycelium (ERM) can actively take up Cr [either in the form of Cr(VI) or Cr(III)] and transport Cr [potentially in the form of Cr(III)-histidine analogues] to mycorrhizal roots but immobilize most of the Cr(III) in the fungal structures. Based on an X-ray absorption near-edge spectroscopy analysis of Cr(VI)-treated roots, we proposed that the intraradical fungal structures can also immobilize Cr within mycorrhizal roots. Our findings confirmed the immobilization of Cr by AMF, which plays an essential role in the Cr(VI) tolerance of AM symbioses.

Corrosion resistance of AA6063-Type Al-Mg-Si alloy by silicon carbide in sodium chloride solution for marine application

The present work focused on corrosion inhibition of AA6063 type (Al-Mg-Si) alloy in sodium chloride (NaCl) solution with a silicon carbide inhibitor, using the potentiodynamic electrochemical method. The aluminium alloy surface morphology was examined, in the as-received and as-corroded in the un-inhibited state, with scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS). The results obtained via linear polarization indicated a high corrosion potential for the unprotected as-received alloy. Equally, inhibition efficiency as high as 98.82% at 10.0 g/v silicon carbide addition was obtained with increased polarization resistance (R p), while the current density reduced significantly for inhibited samples compared to the un-inhibited aluminium alloy. The adsorption mechanism of the inhibitor aluminium alloy follows the Langmuir adsorption isotherm. This shows that the corrosion rate of aluminium alloy with silicon carbide in NaCl environment decreased significantly with addition of the inhibitor.

Gallic acid grafting to a ferrimagnetic bioactive glass-ceramic

Ferrimagnetic bioactive glass ceramics are promising biomaterials in the field of bone substitution and cancer treatment for their ability to bond to bone (bioactive behavior) and to be heated by the application of an external magnetic field (hyperthermia). Surface functionalization of these materials with polyphenols is a challenging and innovative strategy in order to impart them additional functional and specific properties (e.g. antioxidant, anticancer and antibacterial). Gallic acid (GA) is a phenolic acid which can be considered a good model molecule for polyphenols due to its simple structure and representative properties. In the present paper GA has been grafted to a ferrimagnetic glass ceramic (SC-45), in bulk and powder forms, in view of its potential clinical applications (such as hyperthermic treatment of cancer combined with the anticancer action of GA). The grafting process has been optimized in order to preserve GA activity. The effectiveness of the functionalization procedure has been demonstrated by means of Scanning Electron Microscopy equipped with Energy Dispersive Spectroscopy (SEM-EDS), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric analysis-gas evolved analysis (TGA-EGA) and Folin&Ciocalteu tests (F&C). Release tests have been performed in double distilled water at 37°C and 43°C to verify the stability of the material.

Crystallization Kinetics of CaO-SiO<sub>2</sub>(CaO/SiO<sub>2</sub>=1)-TiO<sub>2</sub>-10 mass%B<sub>2</sub>O<sub>3</sub> Glassy Slag by Differential Thermal Analysis

Crystallization characteristics of the CaO-SiO2-TiO2-10%B2O3 glassy slag at w(CaO)/w(SiO2)=1 have been studied by Differential Thermal Analysis (DTA) and Matusita-Sakka method. Crystallization products have been distinguished by employing X-ray diffraction (XRD) and Scanning Electron Microscopy equipped with Energy Dispersive Spectroscopy (SEM-EDS). As the TiO2 content is within 10-18%, the crystal phase precipitated is mainly CaSiO3, and the effective activation energies for crystal growth increase with the increase of TiO2 content. Crystallization mechanism for CaSiO3 shifted from surface crystallization to one-dimensional growth with increase of TiO2. As the TiO2 content in slag further increases to 22% and 26%, CaTiSiO5 becomes the predominant crystal phase precipitated, and the effective activation energies for crystal growth decrease with the increase of TiO2 content. Crystallization mechanism for CaTiSiO5 is mainly surface crystallization. Therefore, with the increase of TiO2 content, the crystallization ability of the CaO-SiO2-TiO2-10%B2O3 glass system decreases initially and then increases.

Pulverized-Coal Deposits Collected Under Staged and Unstaged Oxy-Fuel Conditions for Four U.S. Coals

Coal ash deposits were collected in a 160 kWth, down-fired oxy-coal reactor under staged and unstaged conditions for four different coals at two locations. The deposits were embedded in epoxy for imaging and element composition analysis using scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS). Particles were found to be categorized into four groups: non-porous non-molten mineral matter, unburned coal/char, porous non-molten mineral matter, and molten mineral matter. Near burner deposits on the upstream side of tubes in cross-flow contained all four types of particles. Downstream deposits contained primarily molten mineral matter, approximately an order of magnitude smaller in size. No measureable chlorine (greater than 1%) was found in the deposits. Sulfur was observed to correlate with coal calcium content in oxidizing regions. The only major difference between the air and oxy-combustion deposits measured previously was the sulfur concentration; deposits collected with oxy-combustion contained higher concentrations of sulfur.

Effect of Thermal Treatment on Intermetallic Phases of Fe/Al Structural Transition Joints

In ship industries, the welding of aluminium and steel is an important task to perform, however it is impossible to directly weld aluminium to steel by conventional fusion welding processes. To overcome this difficulty, the Fe/Al explosion-welded structural transition joints (aluminium 5083: aluminium 1050: steel St.52-3N) is used as intermediate strip to join aluminium and steel together. In this study, the thermal sensitizing temperature of 300 oC is used to study the changes of intermetallic phases in Fe/Al structural transition strip. The techniques used for this study are: scanning electron microscopy equipped with energy dispersive spectroscopy (SEM/EDS), optical microscopy (OM), and Image Analyzer to study the microstructure's change and to quantify the amount of intermetallic phase present in the specimen. According to the obtained results, the amount of intermetallic phase precipitation (f$) in the aluminium 5083 layer has significantly increased after thermal sensitizing at 300 oC for both 5 and 15minute of heat treatment.

Cyclic Oxidation Behavior of IN 718 Superalloy in Air at High Temperatures

Ni-base superalloy IN 718 was cyclically oxidized in laboratory air at temperatures ranging from 750 to 950 °C for up to 12 cycles (14 h/cycle). The kinetic behaviour as well as the surface morphology, and the oxide phases of the scales were characterized by means of weight gain measurements, cyclic oxidation kinetics, scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS), and X-ray diffraction (XRD) analysis techniques. The results showed that as the oxidation temperature increased, the oxidation rate, the external scale thickness, and internal oxidation zone increased. It was suggested that the oxidation rate was controlled by the diffusion of substrate elements in the alloy and the inward diffusion of oxygen through the oxide scale. The oxidation kinetics followed a sub-parabolic rate law and, the activation energy of oxidation was 249 ± 20 kJ mol−1. The scaling process was controlled mainly by the diffusion of chromium, titanium, manganese, and oxygen ions through the chromia scale. IN 718 showed low weight gain and very slow reaction rates of substrate elements at 750 °C. At 850 °C, a continuous and very thin oxide scale was formed. At 950 °C, XRD and EDS-elemental mapping analysis revealed that a complex oxide scale had formed. It consisted of an outermost layer of TiO2–MnCr2O4 spinels, inner layer of Cr2O3, and the inner most layer composed of Ni3Nb enriched with Nb, Ti and Al oxides underneath the chromia layer. The oxide scale at this temperature seemed to be thicker layer, significant spallation and volatilization had apparently occurred, and greater internal corrosion was identified. The doping effect of titanium was observed, where it was found to be diffused through the chromia scale to form TiO2 at the oxide-gas interface as well as internally and at the oxide alloy interface. The amount of rutile (TiO2) at the oxide surface increased with temperature. In view of Mn contents in the alloy, the manganese–chromium spinel oxide was inferred to have played an important role in cyclic oxidation behaviour of IN 718, where the change in oxidation kinetic was noted. The Al contents would cause internal Al-rich oxide formation at grain boundaries.

Leaching Behaviors of Arsenic from Arsenic-Iron Hydroxide Sludge during TCLP

The toxicity characteristic leaching procedure (TCLP) is normally used to evaluate if sludge should be managed as hazardous waste. This study examines immobilization mechanisms of arsenic onto arsenic-iron hydroxide sludge, the byproduct of arsenic removal by coagulation with ferric chloride. The leaching mechanism of arsenic from the sludge due to the TCLP is also investigated. Microscopic characterization techniques including scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were employed to characterize the sludge samples with the As-to-Fe ratios of 0.07 to 0.15 before and after the TCLP. SEM-EDS and FT-IR results suggested that arsenic-iron hydroxide sludge be ferric hydroxide, whose surface is inner or outer spherically sorbed by arsenic, rather than the precipitate of insoluble iron-arsenic compounds such as Fe(AsO )4 . This is also confirmed by XRD results, which revealed that none of suc...