Combination Of Scanning Electron Microscopy Research Articles

A highlightedly improved method for isolating and characterizing calcium oxalate crystals from tubercles of Mammillaria schumannii

BackgroundCalcium oxalate (CaOx) is the most prevalent and widespread biomineral in plants and is involved in protective and/or defensive functions against abiotic stress factors. It is, however, expected that this function has an extremely significant contribution to growth processes in plants bearing large amounts of CaOx, such as cacti growing in desert environment.ResultsIn our research, small-sized CaOx crystals (≤ 20 µm) with tetrahedral or spherical shapes were observed to dominate in each epidermal and cortical cell from the tubercles of Mammillaria schumannii, a species from the Cereoideae subfamily, having tubercles (main photosynthetic organs) united with adjacent ones almost into ridges on its stem. Because they have potential significant functions, differential centrifugations after mechanical blending were used to obtain these small-sized CaOx crystals, which extremely tend to adhere to tissue or suspend in solution. And then the combined Scanning Electron Microscope Energy Dispersive System (SEM–EDS) and Raman spectroscopy were further performed to demonstrate that the extracted crystals were mainly CaC2O4·2H2O. Interestingly, spherical druses had 2 obvious abnormal Raman spectroscopy peaks of -CH and -OH at 2947 and 3290 cm−1, respectively, which may be attributed to the occluded organic matrix. The organic matrix was further extracted from spherical crystals, which could be polysaccharide, flavone, or lipid compounds on the basis of Raman spectroscopy bands at 2650, 2720, 2770, and 2958 cm−1.ConclusionsHere we used a highlightedly improved method to effectively isolate small-sized CaOx crystals dominating in the epidermal and cortical cells from tubercles of Mammillaria schumannii, which extremely tended to adhere plant tissues or suspend in isolation solution. And then we further clarified the organic matrix getting involved in the formation of CaOx crystals. This improved method for isolating and characterizing biomineral crystals can be helpful to understand how CaOx crystals in cacti function against harsh environments such as strong light, high and cold temperature, and aridity.

Impact of Solution {Ba2+}:{SO42-} on Charge Evolution of Forming and Growing Barite (BaSO4) Crystals: A ζ-Potential Measurement Investigation.

The impact of solution stoichiometry on formation of BaSO4 (barite) crystals and the development of surface charge was investigated at various predefined stoichiometries (raq = 0.01, 0.1, 1, 10, and 100, where raq = {Ba2+}:{SO42-}). Synthesis experiments and zeta potential (ζ-potential) measurements were conducted at a fixed initial degree of supersaturation (Ωbarite = 1000, where Ωbarite = {Ba2+}{SO42-}/Ksp), at circumneutral pH of ∼6, 0.02 M NaCl, and ambient temperature and pressure. Mixed-mode measurement-phase analysis light scattering (M3-PALS) showed that the particles stayed negative for raq < 1 during barite crystal formation and positive for raq > 1. At raq = 1, two populations with a positive or negative ζ-potential prevailed for ∼2.5 h before a population with a circumneutral ζ-potential (-10 to +10 mV) remained. We relate the observations of particle charge evolution to particle size and morphology evolution under the experimental conditions. Furthermore, we showed that the ζ-potential became more negative when the pH was increased for every raq. In addition, our results demonstrated that the type of monovalent background electrolyte did not influence the ζ-potential of barite crystals significantly, although NaCl showed slightly different behavior compared to KCl and NaNO3. Our results show the important role of surface charge (evolution) during ionic crystal formation under nonstoichiometric conditions. Moreover, our combined scanning electron microscopy and ζ-potential results imply that the surface charge during particle formation can be influenced by solution stoichiometry, besides the pH and ionic strength, and may aid in predicting the fate of barite in environmental settings and in understanding and improving industrial barite (surface chemistry) processes.

Effect of sulfur content on precipitation behaviour of MnS-containing inclusions in X70 pipeline steel

The presence of oxide-MnS complex inclusions is beneficial for the improvement of hydrogen resistance in pipeline steel. The effect of S and Mg contents on the generation mechanism of MnS, MgAl2O4, and MgO inclusions, and the heterogeneous nucleation principle of MnS on the surfaces of MgAl2O4 and MgO were revealed using laboratory experiments, thermodynamic calculations, and density functional theory (DFT) computations. The inclusion characteristics in steel were evaluated by using a Scanning Electron Microscope in combination with an Energy Dispersive Spectrometer (SEM + EDS). It has been found that as the Mg content increased, MgAl2O4 transformed into MgO, which can be well predicted by thermodynamic calculations. It was found that MnS exhibited the ability to nucleate heterogeneously on the surfaces of MgO and MgAl2O4 inclusions. Furthermore, proper S content (approximately 30 ppm) can facilitate the formation of oxide-MnS complex inclusions, excess S content was not desired. The smaller the oxide inclusion, the easier to form wrapped MnS on the oxides. The nucleation ability of MnS and MgAl2O4 was identified by DFT calculations and found that they followed the order of (111)MnS//(111)MgAl2O4>(100)MnS//(100)MgAl2O4>(110)MnS//(110)MgAl2O4. Furthermore, the heterogeneous nucleation ability of MnS and MgO followed in the order of (111)MnS//(111)MgO > (100)MnS//(111)MgO > (100)MnS//(100)MgO. This study provides theoretical evidence supporting the heterogeneous nucleation ability of MnS on the surfaces of MgO and MgAl2O4. Moreover, it helps bridge the disparity between the calculation of MnS and MgO nucleation using the two-dimensional mismatch degree and the experimental findings.

Experimental study on the mechanical behavior of EICP-casein-treated calcareous sand

In order to protect and develop marine resources, it is essential to reinforce the calcareous sand foundation on coral reefs during engineering construction. This study proposes a novel approach that combines enzyme-induced carbonate precipitation (EICP) with casein to solidify calcareous sand, which overcomes the issues of low calcium carbonate crystallization and insufficient cementation strength encountered in the pure EICP method. This study investigated the reinforcement effects and mechanisms of the combined method across various scales. Sonic time testing revealed an initial decline in sample density followed by a gradual increase, with the lowest density observed at 10% casein content. Sample strength depends on casein dosage and curing time. Overall, the trend in sample strength showed an initial decrease followed by a gradual increase, with 10% casein content again resulting in the lowest strength. The measured experimental groups achieved a minimum strength of approximately 1.17 MPa and a maximum strength of around 6.34 MPa. As casein concentration rises, the optimal curing time increases from 12–48 h. Microscopic experiments reveal casein expansion and dissolution in the EICP liquid, explaining UCS value changes with casein dosage and curing time. Combining scanning electron microscopy and microscopic experiments highlights the cementitious material’s vital role in strengthening samples. In conclusion, combining EICP and casein for solidifying calcareous sand is technically feasible and highly effective with significant reinforcement effects.

Diffusion of Alloying Cobalt Oxide (II, III) into Electrical Steel.

This paper aims to reduce power loss in electrical steel by improving its surface resistivity. The proposed approach involves introducing additional alloying elements through diffusion once the steel sheet reaches the desired thickness. Various effective techniques have been suggested and tested to enhance the resistivity of the strip. The method entails creating a paste by combining powdered diffusing elements with specific solutions, which are then applied to the steel's surface. After firing the sample, a successful transfer of certain elements to the steel surface is achieved. The amount and distribution of these elements can be controlled by adjusting the paste composition, modifying the firing parameters, and employing subsequent annealing procedures. This study specifically investigates the effectiveness of incorporating cobalt oxide (II, III) into non-oriented silicon iron to mitigate power loss. The experimental samples consist of non-oriented electrical steels with a composition of 2.4 wt% Si-Fe and dimensions of 0.305 mm × 300 mm × 30 mm. Power loss and permeability measurements are conducted using a single strip tester (SST) within a magnetic field range of 0.5 T to 1.7 T. These measurements are performed using an AC magnetic properties measurement system under controlled sinusoidal conditions at various frequencies. The research explores the impact of cobalt oxide (II, III) addition, observing successful diffusion into the steel through the utilization of a paste based on sodium silicate solution. This treatment results in a significant reduction in power loss in the non-oriented material, with power loss reductions of 14% at 400 Hz and 23% at 1 kHz attributed to the elimination of a porous layer containing a high concentration of the diffusing element. The formation of porosity in the cobalt addition was found to be particularly sensitive to firing temperature near the melting point. The diffusion process was examined through scanning electron microscopy (SEM) in combination with energy-dispersive X-ray spectroscopy (EDS). The results demonstrate improved power losses in the coated samples compared with the uncoated ones. In conclusion, this study establishes that the properties of non-oriented electrical steels can be enhanced through a safer process compared with the methods employed by previous researchers.

Influence of graphene content on the microstructure and properties of GNPs/2024Al composites

In this study, reinforced 2024Al-based composites with different graphene nanoplatelets (GNPs) contents (0 %, 0.25 wt%, 0.5 wt%, 1 wt%, 1.5 wt%) were prepared by the Hot Pressed Sintering process method. The impacts of graphene content on its microstructure, mechanical properties and corrosion resistance were investigated using hardness test, tensile property test and intergranular corrosion property test. Furthermore, the microscopic mechanism was explored by combining scanning electron microscopy (SEM), XRD analysis and electrochemical analysis. It was demonstrated that with the increase of GNPs content, the strengthening effect of the composite showed a trend of increasing and then decreasing, and the best strengthening effect of 0.5 wt% GNPs/2024Al composite was achieved. When the solution and aging was 12 h, the hardness was 161.74 HV0.2 and the tensile strength was 476 MPa. The GNPs could reduce the anti-intergranular corrosion performance of 2024Al. As the content of GNPs increases, the corrosion current density of the composite gradually increases and the anti-corrosion performance gradually decreases.

Competitive role of primary [formula omitted] precipitates and annealing twins on the heterogeneous deformation of a polycrystalline ni-based superalloy: Crystal plasticity modeling and experiments

A crystal plasticity modeling framework is developed and used in combination with experiments for studying the deformation behavior of a polycrystalline Ni-based superalloy. In particular, the monotonic stress-strain response across a range of temperatures and the misorientation development at room temperature are predicted. The model accounts for individual deformation of the matrix and primary γ′ phases, with consideration for the various strengthening mechanisms observed in these alloys. The as-received microstructure has been characterized using Energy Dispersive X-Ray Spectroscopy (EDS) and the concentration of the solute atoms present in the γ and primary γ′ phases obtained from these measurements are used to inform the solute solution strengthening model. Further, the Electron Back Scatter Diffraction (EBSD) microstructures are directly used as inputs for the simulations. The model is first calibrated to the experimental stress-strain response at 293 K and 923 K and then validated by predicting the mechanical response at 523 K and 723 K. Interrupted tensile testing has been performed using a combination of Scanning Electron Microscopy (SEM) and EBSD to study the misorientation developments during deformation. These deformed microstructures are correlated with the simulated EBSD microstructures, in terms of the competitive misorientation developments at grain boundaries, annealing twin boundaries and phase interfaces. Higher misorientation developments were observed at the twin boundaries as compared to the grain boundaries and phase interfaces, indicating a higher propensity of heterogeneous deformation.

Transient melt formation and its effect on conversion phenomena during nuclear waste vitrification – HT‐ESEM analysis

AbstractAlthough the vitrification of nuclear waste has a decades‐long history, numerous opportunities still exist to improve its efficiency and to increase the waste loading in glass. This is especially true for the vitrification of low‐activity waste (LAW), which has been historically treated by other immobilization technologies and is less mature than high‐level waste (HLW) vitrification. In this work, we address one of the least understood phenomena during the conversion of nuclear waste feeds to glass—the formation of molten salt and transient glass‐forming melt. Using high‐temperature environmental scanning electron microscopy (HT‐ESEM) in combination with X‐ray diffraction, thermogravimetry, and evolved gas analysis, we have analyzed the complex chemical reactions and phase transitions as they occur during melting of representative HLW and LAW melter feeds. We evaluated the compositions of amorphous phases and the fractions of salt components, and estimated the fractions of molten salt phases present in the feeds as a function of temperature. We show that the maximum fraction of molten salts is ∼4 % and ∼28 % during HLW and LAW feed melting, respectively, and discuss the possibility of molten salt migration in LAW feeds. We also argue that the presence of significant fractions of molten salt phase can hinder the retention of rhenium (and, hence, radioactive technetium), and discuss how the properties of molten salt phase and transient glass‐forming melt are related to primary foam formation and behavior. Finally, we summarize key unanswered questions requiring further research to increase the understanding of the conversion process and enhance the nuclear waste vitrification efficiency.

High performance all-para-aramid paper prepared by impregnating heterocyclic aramid into poly(p-phenylene terephthalamide) microfiber/nanofiber-based paper

All-para-aramid paper with both excellent mechanical properties and thermal stability is of great significance for the manufacture of specialty honeycomb materials. Herein, a facile method is reported for the preparation of high performance all-para-aramid paper by impregnating heterocyclic aramid (HA) solution into a para-aramid paper (PAP) produced with poly(p-phenylene terephthalamide) (PPTA) short fibers and polymerization-induced para-aramid nanofibers (PANFs). Field emission scanning electron microscopy in combination with microscopic Fourier transform infrared spectroscopy were used to confirm successful coating of HA on paper surface and infiltration of HA inside PAP. Since HA molecules in solution have similar structure to PPTA molecules and much stronger ability to form hydrogen bonds than PPTA fibers, they can effectively act as a binder for both types of PPTA fibers, greatly enhancing the interfacial adhesion between fibers and densifying the paper structure. As a result of these structural changes and also of the excellent mechanical properties of HA itself, the HA-impregnated PAPs (HA/PAPs) exhibit much better mechanical properties than neat PAP. The tensile strength of HA/PAP can be up to 128.5 MPa, 4.8 times that of neat PAP. The internal bond strength of HA/PAP can reach 356.1 J/m2, being 4.5 times that of neat PAP, showing dramatically improved delamination resistance. All-para-aramid HA/PAPs possess intrinsically excellent thermal stability and flame retardancy.

Aging behavior of biodegradable polylactic acid microplastics accelerated by UV/H2O2 processes

The usage of biodegradable plastics is expanding annually due to worldwide plastic limits, resulting in a substantial number of microplastics (MPs) particles formed from biodegradable plastic products entering the aquatic environment. Until now, the environmental behaviors of these plastic product-derived MPs (PPDMPs) have remained unclear. In this work, commercially available polylactic acid (PLA) straws and PLA food bags were used to evaluate the dynamic aging process and environmental behavior of PLA PPDMPs under UV/H2O2 conditions. By combining scanning electron microscopy, two-dimensional (2D) Fourier transform infrared correlation spectroscopy (COS) and X-ray photoelectron spectroscopy, it was determined that the aging process of the PLA PPDMPs was slower than that of pure MPs. The 2D-COS analysis revealed that the response orders for the functional groups on the PLA MPs differed during the aging process. The results demonstrated that the oxygen-containing functional groups of the PLA PPDMPs were the first to react. Subsequently, the –C–H and –C–C− structural responses began, and the polymer backbone was ruptured by the aging process. However, the aging of the pure-PLA MPs started with a brief oxidation process and then breakage of the polymer backbones, followed by continuous oxidation. Moreover, compared to the PLA PPDMPs, the pure-PLA MPs exhibited a greater adsorption capacity, which was increased by 88% after aging, whereas those of the two PPDMPs only increased by 64% and 56%, respectively. This work provides new insights into the behaviors of biodegradable PLA MPs in aquatic environments, which is critical for assessing the environmental risks and management policies for degradable MPs.

Corrosion behavior of magnesium in aqueous sulfate-containing electrolytes

Studies have been conducted on the corrosive behavior of magnesium in aqueous sulfate electrolytes (0.5 mol/L MgSO4; 0.5 mol/L Na2SO4; 0.5 mol/L MgSO4 + 0.5 mol/L Na2SO4).The composition structure and morphology of the surface of the samples were studied using scanning electron microscopy in combination with X-ray spectral microanalysis. The results of the experiments showed the formation of a surface film inhomogeneous in its structure and composition with the main components Mg(OH)2 and MgO. An increase in the exposure time of the electrode in solution led to the formation of microcracks on the main film caused by internal stress because of hydration of magnesium oxide produced during corrosion. The salt composition of the electrolyte determines the morphology and thickness of corrosion films due to differences in the solubility of the products formed during the hydrolysis of magnesium oxide and the kinetics of this process.Applying the methods of scanning electron microscopy X-ray electron analysis gravimetry and voltammetry it has been established that at various stages of magnesium corrosion in different electrolytes the growth rates of corrosion films are determined by the kinetics of magnesium oxide formation its hydration and dissolution followed by crystallization in the form of a brucite phase of loose sediments on the surface.

Analysis of Structural Degradation Effects in a Solid Oxide Fuel Cell after Long-Term Operation

An in-depth post mortem analysis was conducted on cells from a stack with an operation time of 100,000 h. In doing so, the focus of the investigations was mainly on the air electrode side. By utilizing scanning electron microscopy in combination with energy dispersive X-ray spectroscopy the microstructure and the localized chemical composition was investigated. Additionally, the structural changes of the cells were analyzed by X-ray diffraction, by Raman spectroscopy, and by synchrotron-based µ-Laue diffraction measurements. The combination of these advanced analytical tools highlights changes in the structure and chemical composition on the air electrode side caused by various degradation effects after long-term operation.

Microstructure and Mechanical Behavior of Cu-Al-Ni-B Alloys with Thermoelastic Martensitic Transformation

For the first time, using optical, scanning, and transmission electron microscopy and X-ray phase analysis in combination with measurements of tensile mechanical properties, we obtained data on the structural features of the polycrystalline shape-memory eutectoid Cu-Al-Ni-(B) alloys doped by aluminum (of 10 and 14 wt% Al in total amount), nickel (of 3, 4, and 4.5 wt% Ni), and boron (0.02–0.3 wt% B) in various compositions. The effect of boron on the grain sizes, structure, phase composition, and mechanical properties of shape memory (SM) alloys has been studied. The localization of aluminum borides in the structure was investigated and an effect of grain growth inhibition in the (α + β) and β Cu-Al-Ni-B alloys was established, both in the cast state of the alloys considered and after their heat treatment.

Inorganic polyphosphate accumulation protects a marine, filamentous cyanobacterium, Anabaena torulosa against uranium toxicity

The intricate dynamics of inorganic polyphosphate (polyP) in response to phosphorus (P) limitation and metal exposure typical of contaminated aquatic environments is poorly understood. Cyanobacteria are important primary producers in aquatic environments that are exposed to P stringency as well as metal contamination. There is a growing concern regarding migration of uranium, generated as a result of anthropogenic activities, into the aquatic environments owing to high mobility and solubility of stable aqueous complexes of uranyl ions. The polyP metabolism in cyanobacteria in context of uranium (U) exposure under P limitation has hardly been explored. In this study, we analyzed the polyP dynamics in a marine, filamentous cyanobacterium Anabaena torulosa under combination of variable phosphate concentrations (overplus and deficient) and uranyl exposure conditions typical of marine environments. Polyphosphate accumulation (polyP+) or deficient (polyP−) conditions were physiologically synthesized in the A. torulosa cultures and were ascertained by (a) toulidine blue staining followed by their visualization using bright field microscopy and (b) scanning electron microscopy in combination with energy dispersive X-ray spectroscopy (SEM/EDX). On exposure to 100 μM of uranyl carbonate at pH 7.8, it was observed that the growth of polyP+ cells under phosphate limitation was hardly affected and these cells exhibited larger amounts of uranium binding as compared to polyP− cells of A. torulosa. In contrast, the polyP− cells displayed extensive lysis when exposed to similar U exposure. Our findings suggest that polyP accumulation played an important role in conferring uranium tolerance in the marine cyanobacterium, A. torulosa. The polyP-mediated uranium tolerance and binding could serve as a suitable strategy for remediation of uranium contamination in aquatic environments.

Nanoscale imaging of quantum dot dimers using time-resolved super-resolution microscopy combined with scanning electron microscopy

Time-resolved super-resolution microscopy was used in conjunction with scanning electron microscopy to image individual colloidal CdSe/CdS semiconductor quantum dots (QD) and QD dimers. The photoluminescence (PL) lifetimes, intensities, and structural parameters were acquired with nanometer scale spatial resolution and sub-nanosecond time resolution. The combination of these two techniques was more powerful than either alone, enabling us to resolve the PL properties of individual QDs within QD dimers as they blinked on and off, measure interparticle distances, and identify QDs that may be participating in energy transfer. The localization precision of our optical imaging technique was ∼3 nm, low enough that the emission from individual QDs within the dimers could be spatially resolved. While the majority of QDs within dimers acted as independent emitters, at least one pair of QDs in our study exhibited lifetime and intensity behaviors consistent with resonance energy transfer from a shorter lifetime and lower intensity donor QD to a longer lifetime and higher intensity acceptor QD. For this case, we demonstrate how the combined super-resolution optical imaging and scanning electron microscopy data can be used to characterize the energy transfer rate.

High-Resolution Imaging Methods for Identification of Calcium Crystal Types in Osteoarthritis

The detection and differentiation of BCP and CPP crystals in calcified tissue is an important factor in the context of research and potential future treatment of osteoarthritis and chondrocalcinosis. Current standard methods originate from clinical practice and often lack precision in the correct identification of the calcium crystal type. In this work, a step-by-step guide for the use of the high-resolution imaging methods of tissue sections, Raman spectroscopy and scanning electron microscopy (SEM) in combination with energy-dispersive X-ray spectroscopy (EDS), for calcium crystal identification is presented. Sample preparation including Von Kossa staining, measurement and measurement parameters, data processing and data analysis methods are discussed and described. Furthermore, the different methods are compared to show advantages and disadvantages. Overall, Raman spectroscopy is a reasonable method from an economic point of view and regarding the time/effort required for acquiring highly reliable data in calcium crystal identification. Potentially, semi-quantitative results can be obtained with little effort and without the destruction of the respective test sample. The analysis/penetration depth during the Raman measurements, which is not precisely defined, poses a potential problem for accuracy. SEM can also be used for this task but requires more time, advanced technical knowledge and a pre-treatment of the samples using, e.g., gold sputtering, which may distort further analysis on the specific specimen. Therefore, this technique yields additional value compared to Raman spectroscopy only with additional research questions needed to be answered in the same sample, such as analysis of the sample topography or analysis of other unknown particles/deposits using EDS. The methods described in this manuscript are helpful for retrospective analyses in the context of research, but can also be used for potential future treatment strategies to discriminate between osteoarthritis and chondrocalcinosis patients.

Corrosion Susceptibility of Passive Films on 1060, 2024, and 5083 Aluminum Alloys: Experimental Study and First-Principles Calculations

The corrosion characteristics of passive films on 1060, 2024 and 5083 aluminum alloys formed in citric acid solution are studied in Cl–-containing solutions by combining scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The passive film on 1060 pure Al exhibits the best corrosion resistance while the presence of alloying elements (Cu and Mg) in the passive films reduce the corrosion resistance of the passive films on 2024 and 5083 Al alloys. According to first-principles calculations, Cu/Mg doping γ-Al2O3 surfaces are looser and more reactive than pure γ-Al2O3 (110) surface, and Cl adsorption behavior is changed in Cu/Mg doping γ-Al2O3 surfaces. This illuminates the difference of corrosion resistances of 1060, 2024 and 5083 aluminum alloys from the aspects of the passive film structure and interaction of chlorine ions with the passive films.

Detecting irradiation-induced strain localisation on the microstructural level by means of high-resolution digital image correlation

Materials subjected to irradiation damage often undergo local microstructural changes that can affect their expected performance. To investigate such changes, this work proposes a novel approach to detect strain localisation caused by irradiation-induced damage in nuclear materials on the microstructural level, considering a statistically relevant number of grains. This approach determines local strains using high-resolution digital image correlation (HRDIC) and compares them with the underlying material microstructure. Sets of images captured before and after irradiation are compared to generate full-field displacement maps that can then be differentiated to yield high-resolution strain maps. These strain maps can subsequently be used to understand the effects of irradiation-induced dimensional change and cracking on the microscale. Here, the methodology and challenges involved in combining scanning electron microscopy (SEM) with HRDIC to generate strain maps associated with radiation-induced damage are presented. Furthermore, this work demonstrates the capabilities of this methodology by analysing three different materials subjected to proton irradiation: a zircaloy-4 (Zry-4) metal irradiated to 1 & 2 dpa, and two ceramics based on MAX phase compounds, i.e., the Nb4AlC3 ternary compound and a novel (Ta,Ti)3AlC2 solid solution, both irradiated to -0.1 dpa. These results demonstrated that all materials show measurable expansion, and the very high strains seen in the MAX phase ceramics can be easily attributed to their microstructure. Grain-to-grain variability was observed in Zry-4 with a macroscopic expansion along the rolling direction that increased with irradiation damage dose, the Nb4AlC3 ceramic showed significant expansion within individual grains, leading to intergranular cracking, while the less phase-pure (Ta,Ti)3AlC2 ceramic exhibited very high strains at phase boundaries, with limited expansion in the binary carbide phases. This ability to measure irradiation-induced dimensional changes at the microstructural scale is important for designing microstructures that are structurally resilient during irradiation.

Study on the Effectiveness of Sulfate Reducing Bacteria to Remove Heavy Metals (Fe, Mn, Cu, Cr) in Acid Mine Drainage

Aiming at the problem of environmental pollution caused by heavy metals such as Fe, Mn, Cu, and Cr, Sulfate Reducing Bacteria (SRB) were enriched in mining soil. SRB was added to AMD containing different concentrations of Fe, Mn, Cu, and Cr by batch experiments to explore the potential of SRB for treating heavy metals in AMD. Testing combining Scanning Electron Microscopy–Energy Dispersive Spectroscopy (SEM-EDS), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS) revealed the mechanism by which heavy metal ions were removed by SRB. The results showed that SRB had a strong ability to remove total Fe in the concentration range of 0–300 mg/L, and the removal percentage of total Fe reached to 92.16–93.17%. SRB had a good removal effect on total Cu, in the concentration range of 0–20 mg/L, and the removal percentage of total Cu reached to 79.79–81.80%. SRB had a good removal effect on total Cr as well; SRB activity would probably not be inhibited for total Cr concentrations below 500 mg/L. The ability to solidify different heavy metal ions using SRB was as follows: total Cr &gt; total Fe &gt; total Mn &gt; total Cu. When SRB removed Fe2+ there was precipitation at the same time, appearing as black granules. This precipitation consisted mainly of FeS, and contained small amounts of Fe3(PO4)2-8H2O, FeCO3, Fe(OH)2, Fe(OH)3, and Fe2S as well.

Low-temperature one-step solid state chemical synthesis of GaN nanosheets for conquering polysulfides in Li–S battery

Gallium nitride (GaN) nanosheets have been prepared as an active material for conquering polysulfides in Lithium–Sulfur (Li–S) batteries via one simple synthetic route at 550 °C. The process was carried out in a stainless steel autoclave by using gallium nitrate hydrate, sodium amide and metallic lithium as starting materials. The product was proven to be hexagonal GaN nanosheets by combined X-ray powder diffraction (XRD) pattern and Scanning electron microscopy (SEM). The GaN nanosheets were then used to coat on the Li–S battery separator, and the result proves an effective inhibition of the shutting problem and gives excellent electrochemical properties compared with traditional separators or GaN additives. The battery assembled by GaN coated separator shows good cycling stability with 408 mAh/g and a low capacity fading of 0.6‰ per cycle from 11th to 480th cycle at 2 C due to high utilization of the sulfur-based active species.