Electron Microscopy-energy Dispersive X-ray Research Articles

Enamel biomineralization under the effects of indomethacin and celecoxib non-steroidal anti-inflammatory drugs

The aim of this study was to explore the effects of nonsteroidal anti-inflammatory drugs on biomineralization of enamel. Sixty C57Bl6 male mice were used, which were assigned into three groups: celecoxib (n = 20) or indomethacin (n = 20) treatment for a period of 28 days or received no medication (control group, n = 20). Visual inspection and microcomputed tomography were used to analyze enamel morphology. Scanning electron microscopy–Energy dispersive X-ray and Knoop microhardness test were used to quantify chemical element content (Ca, P, C, O) and enamel microhardness, respectively. Tissues were collected to investigate the synthesis, activity or nuclear translocation of metalloproteinase-20, transcription factor Runx2, dentin sialoprotein and cyclooxygenase-2 enzyme by means of immunohistochemistry, in situ zymography and indirect immunofluorescence. Treatment with indomethacin and celecoxib reduced the Ca and P content, microhardness and mineral density in enamel. Treatment with nonsteroidal anti-inflammatory drugs caused an accumulation of metalloproteinase-20 and overall increased enzymatic activity in enamel matrix, while the synthesis of the transcription factor Runx2 was inhibited by these drugs. Interestingly, indomethacin inhibited Runx2 translocation to the nucleus whereas celecoxib did not. Those findings show that non-steroidal anti-inflammatory drugs impact the enamel biomineralization and could be involved in the etiology tooth enamel defects if used during the period of tooth formation and mineralization.

Casein phosphopeptide-calcium chelate: Preparation, calcium holding capacity and simulated digestion in vitro

In this work, CPP-Ca chelate was synthesized by chelating casein phosphopeptide (CPP) and calcium and characterized by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The antioxidant activity and calcium holding capacity of CPP-Ca were evaluated and its secondary structure transition was monitored during gastrointestinal digestion by in situ Raman spectroscopy. The results demonstrated that calcium chelating rate reached 40 % and calcium ion was bound to CPP mainly through the interaction of carboxyl and amino groups. The result of calcium holding capacity confirmed the formation of calcium phosphate precipitates could be delayed by 10–15 min with increasing CPP concentration. In vitro simulated digestion revealed CPP-Ca exhibited excellent calcium solubility and its secondary structural changes occurred, especially α-helix and β-sheet content. These findings provided significant insights into enhancing bioavailability of calcium supplements and developing of calcium functional foods for human and animals.

Foliar-applied nanoscale zero-valent iron (nZVI) and iron oxide (Fe3O4) induce differential responses in growth, physiology, antioxidative defense and biochemical indices in Leonurus cardiaca L

The impacts of nZVI and iron oxides on growth, physiology and elicitation of bioactive antioxidant metabolites in medicinal aromatic plants must be critically assessed to ensure their safe utilization within the food chain and achieve nutritional gains. The present study investigated and compared the morpho-physiological and biochemical changes of Leonurus cardiaca L. plants as affected by various concentrations (0, 250, 500 and 1000 mg L−1) of nZVI and Fe3O4. The foliar uptake of nZVI was verified through Scanning Electron Microscopy (SEM) images and Energy Dispersive X-ray (EDX) analytical spectra. Plants exposed to nZVI at low concentration showed comparatively monotonic deposition of NPs on the surface of leaves, however, the agglomerate size of nZVI was raised as their doses increased, leading to remarkable changes in anatomical and biochemical traits. 250 mg L−1 nZVI and 500 mg L−1 Fe3O4 significantly (P < 0.05) increased plant dry matter accumulation by 37.8 and 27% over the control, respectively. The treatments of nZVI and Fe3O4 at 250 mg L−1 significantly (P < 0.01) improved chlorophyll a content by 22.4% and 15.3% as compared to the control, and then a rapid decrease (by 14.8% and 4.1%) followed at 1000 mg L−1, respectively. Both nZVI and Fe3O4 at 250 mg L−1 had no significant impact on malondialdehyde (MDA) formation, however, at an exposure of 500–1000 mg L−1, the MDA levels and cellular electrolyte leakage were increased. Although nZVI particles could be utilized by plants and enhanced the synthesis of chlorophylls and secondary metabolites, they appeared to be more toxic than Fe3O4 at 1000 mg L−1. Exposure to nZVI levels showed positive, negative and or neutral impacts on leaf water content compared to control, while no significant difference was observed with Fe3O4 treatments. Soluble sugar, total phenolics and hyperoside content were significantly increased upon optimum concentrations of employed treatments-with 250 mg L−1 nZVI being most superior. Among the extracts, those obtained from plants treated with 250–500 mg L−1 nZVI revealed the strong antioxidant activity in terms of scavenging free radical (DPPH) and chelating ferrous ions. These results suggest that nZVI (at lower concentration) has alternative and additional benefits both as nano-fertilizer and nano-elicitor for biosynthesis of antioxidant metabolites in plants, but at high concentrations is more toxic than Fe3O4.

Gadolinium enrichment in association with the magnetic fraction of fly ash: Real or an illusion?

Gadolinium, and possibly praseodymium, are relatively enriched in the magnetic fractions of Class F fly ashes from Central Appalachian coal sources. Although the enrichment is evident in the inductively coupled plasma–atomic emission spectroscopy (ICP-AES) determinations of the rare earth content, transmission electron microscopy–energy dispersive x-ray spectroscopy (TEM-EDS) examination of the fly ash fails to show the sites of the Gd or Pr. This apparent lack of correlation could be due to the inability of the EDS to detect low concentrations of the rare earth elements definitively; interferences in the analytics, leading to false positives in the chemical analysis; or the overlap of the energies of Gd and/or Pr with more abundant elements, leading to inaccurate negative results.

Efficient environmental recovery of Au(I) from thiosulfate solution on triphenylphosphine-oxide-modified vermiculite

Natural materials that are economical and environmentally benign are being explored as adsorbent bases for recovering Au(I) from thiosulfate solution via an efficient grafted functional group. In this work, natural vermiculite (VE) modified with triphenylphosphine oxide (TPPO) was used to adsorb Au(I) from thiosulfate solution, and it's gold recovery performance and adsorption mechanism. Fourier transform infrared spectroscopy, scanning electron microscopy–energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and nitrogen adsorption were used to characterize the adsorbents. TPPO-modified VE (VE-TPPO) showed improved gold adsorption ability at a pH of approximately 10, thiosulfate concentration of approximately 0.1 mol/L and temperature of approximately 25 °C. More than 95% of Au(I) could be recovered, and the loading capacity of Au on VE-TPPO increased with decreasing adsorption temperature, reaching an amount of 4.22 kg/t after once adsorption. TPPO was adsorbed on vermiculite through cationic-π bonds. Au(I) was adsorbed on VE-TPPO by a ligand-exchange mechanism involving charge transfer between PO groups and Au(I). Moreover, the interaction mechanism between TPPO and Au(I) was further validated by density functional theory calculations. The use of natural materials with low cost and environmental impact can make the process of leaching gold with thiosulfate safer and cleaner.

Petrological, mineralogical, and geochemical compositions of coal in the Ombilin Basin, West Sumatra, Indonesia

Coal deposits have received considerable attention in recent years owing to their by-product waste being a promising alternative source of critical elements. The Ombilin Basin is well known as one of the largest coal-producing basins in Indonesia. This study investigated the petrological, mineralogical, and geochemical compositions of four Eocene coal seams in Ombilin Basin basement rock, and their relevance regarding critical element enrichment. Samples of coal and basement rock from the Ombilin Basin were analyzed using thin- and polished-section scanning electron microscope energy-dispersive X-ray spectroscopy, inductively coupled plasma atomic emission spectroscopy, and inductively coupled plasma mass spectrometry. Coals from the Ombilin Basin are high-volatile bituminous C coals with mean random vitrinite reflectance values of 0.58%–0.66%. Vitrinite content is the most dominant maceral (61.06 vol% mmf), followed by liptinite (24.95 vol% mmf), and inertinite (13.75 vol% mmf). Minerals observed in the coal samples comprised pyrite, quartz, and clay. Pyrite was present as discrete crystals, massive crystals, framboidal pyrite, and cell-filling on other macerals. Both syngenetic and epigenetic pyrite was found in the Ombilin coal. Based on the petrological and mineralogical analyses, basement rock in the Ombilin Basin can be divided into four groups: granodiorite, andesite-basaltic, marble, and meta-sediment. In comparison with World Hard Coal and common Chinese coals, some layers/partings in the coal seams in the Ombilin Basin are enriched in U (37.6 ppm), V (175 ppm), and total rare earth elements and yttrium (REY; 126.15 ppm). REY-bearing minerals in the Ombilin coal samples were attributed to clay and sulfide minerals, while others were found as dispersed and scattered, indicating that REY are organically bound. Inorganic materials in Ombilin coal deposits have mainly intermediate-felsic provenance, are derived from Cretaceous granitoid rocks and andesite intrusions, and have been subjected to freshwater conditions.

Characterization and optimization of eco-friendly cementitious materials based on titanium gypsum, fly ash, and calcium carbide residue

• Cementitious materials was prepared by FA, TG, CCR based on RSM under ambient curing. • The influences of FA, TG, CCR or their interaction on different ages was analyzed. • The transformation behavior of Fe 3+ in FTC system was observed. • The hydration mechanism, environmental performance of FTC materials was investigated. Titanium gypsum (TG), fly ash (FA) and calcium carbide residue (CCR) are harmful industrial by-products that need to be addressed. In this study, TG, FA and CCR were selected to prepare the eco-friendly FA-TG-CCR (FTC) cementitious materials. Respond surface methodology (RSM) was undertaken to optimize and understand the influence of design factors of m(TG/FA), m(CCR/FA) and W/B on compressive strength, and the mechanical properties, microstructure, hydration mechanism and environmental performance of FTC cementitious materials were investigated. The morphology and structure were characterized by X-ray diffraction (XRD), thermogravimetry- differential scanning calorimetry (TG-DSC) and Scanning electron microscopy energy dispersive X-ray (SEM-EDX), the concentration of hazardous elements was determined via inductively coupled plasma optical emission spectrometer (ICP-OES). The results show that the optimal mixture with RSM methodology (m(TG/FA) = 30.80 %, m(CCR/FA) = 27.85 %, W/B = 0.62) reached 18.93 MPa at 28 days of curing, which confirmed via experimental verification. The FTC cementitious materials are mainly consist with C-(A)-S-H, ettringite; the existence of Fe 3+ was disadvantageous to early age strength, however partial Fe 3+ participated in the formation of Fe-ettringite as the curing time increased, which is beneficial to later age strength. The leaching results indicate that the FTC materials can effectively consolidate the heavy metal ions in raw materials, and the leaching concentration of ions all meet the Chinese Standard for Pollution Control on the Landfill Site of Municipal Solid Waste. Therefore, the synergistic of FTC material offers a novel approach to the efficient utilization of original TG and other industrial by-product wastes.

A comparison between TGA, SEM-EDX and Raman spectroscopy to assess PVC plasticizer loss

The migration of DINP and ESO plasticizers from PVC in contact with different wrapping materials was studied during artificial aging by combining three analysis methods. Silk paper, LDPE and PET were selected since these materials are widely used to protect PVC in heritage collections. First, Scanning Electron Microscopy (SEM) images and Energy Dispersive X-ray (EDX) analyses confirmed the presence of a plasticizer film at the surface of aged PVC whatever the wrapping material. Plasticizer loss during aging was then investigated after PVC surface cleaning. The overall loss of plasticizers was determined from Thermogravimetric Analysis (TGA) however it appeared to be skewed by the dehydrochlorination state. EDX analysis allowed to follow the plasticizer loss through the oxygen to carbon ratio although an external contamination was detected for some samples. Raman spectroscopy was the only technique providing the quantification of both ESO and DINP plasticizers across aging time. The combination of the three techniques to study the aging of PVC under different conditions thus highlighted the strengths and limits of each one. Finally, the relative mass loss speed was similar for both plasticizers but strongly dependent on the wrapping material. Whereas silk paper and LDPE slowed down the plasticizer loss, acceleration was evidenced in presence of PET.

Nanostructured PbS-Doped Inorganic Film Synthesized by Sol-Gel Route.

IV-VI semiconductor quantum dots embedded into an inorganic matrix represent nanostructured composite materials with potential application in temperature sensor systems. This study explores the optical, structural, and morphological properties of a novel PbS quantum dots (QDs)-doped inorganic thin film belonging to the Al2O3-SiO2-P2O5 system. The film was synthesized by the sol-gel method, spin coating technique, starting from a precursor solution deposited on a glass substrate in a multilayer process, followed by drying of each deposited layer. Crystalline PbS QDs embedded in the inorganic vitreous host matrix formed a nanocomposite material. Specific investigations such as X-ray diffraction (XRD), optical absorbance in the ultraviolet (UV)-visible (Vis)-near infrared (NIR) domain, NIR luminescence, Raman spectroscopy, scanning electron microscopy–energy dispersive X-ray (SEM-EDX), and atomic force microscopy (AFM) were used to obtain a comprehensive characterization of the deposited film. The dimensions of the PbS nanocrystallite phase were corroborated by XRD, SEM-EDX, and AFM results. The luminescence band from 1400 nm follows the luminescence peak of the precursor solution and that of the dopant solution. The emission of the PbS-doped film in the NIR domain is a premise for potential application in temperature sensing systems.

Consequences of anthropogenic activities and beach dynamics on vertical distribution of microplastics in the mid-intertidal sediments of Donghai Island, China.

Microplastic accumulation and resulting degradation are significant threats to the coastal ecosystems around the world. Baseline information on microplastics and their sources is of great importance for a permanent waste management system. The present study focused on the vertical distribution and characteristics of microplastics in the mid-intertidal zone of Donghai Island, China. At eight locations, sediment samples were collected from surface to a depth of 30 cm at intervals of 5 cm. Overall, we found five different polymer types, and vertical distributions of microplastics varied ranging from 0 to 200 particles/kg, with the mean value of 32.92±41.35 particles/kg. Sediment samples collected from all stations contained microplastics with high contribution of fibres. Intruded microplastic materials recorded in sediment samples at a depth of 30 cm demonstrate that microplastics may be present at depths greater than 30 cm. Scanning electron microscopy-energy dispersive X-ray (SEM-EDAX) analysis revealed presence of common elements in the microplastics surface (silicon, aluminium, magnesium, copper, and calcium). Based on the observations and results from this study, we suggest implementing a robust microplastic removal management program in Donghai Island to avoid serious microplastic intrusion effects on benthos and environmental contamination.

The Influence of Concentration on the Formation of Chemical Bath Deposited Copper Tin Sulphide Thin Films: SEM and EDX Studies

Nanostructured copper tin sulphide films have been deposited on the substrate (soda lime glass) via an economical chemical bath deposition method. The scanning electron microscopy (SEM) technique and energy dispersive X-ray analyzer (EDX) method were employed in this work to study the films’ morphology and composition. The EDX data and SEM images confirmed that the content of elements (sulfur, tin, and copper), the shape, and the grain size strongly depended on the concentration of the precursors during the formation of films. Experimental results revealed that a higher atomic percentage of the element could be observed for the films prepared using a higher concentration of solution during the experiment.

Diagnostic kit based on halloysite nanoclay-ionic liquid nanocomposite modified electrode for electrochemical determination of cancer biomarker

Nucleic acid hybridization is occurred between the selective single-stranded nucleic acid sequence and its target sequence, which is one of the essential procedure for electrochemical detection of nucleic acid. microRNA-21 (miRNA-21) is known as a biomarker in various cancers. The determination of miRNA-21 was attained through by hybridization of inosine substituted miRNA-21 specific DNA probe (Pinosine) with its target miRNA-21. In this study, the surface of pencil graphite electrode (PGE) was firstly modified with halloysite nanoclay-ionic liquid (HNT/IL) nanocomposite. The characterization of surface was performed by Scanning Electron Microscope (SEM) images and Energy Dispersive X-Ray Analysis (EDX) analysis, and the differences at surface modifications were also shown by electrochemical methods with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). For sensitive and selective determination of miRNA-21, Pinosine and target miRNA concentration, immobilization and hybridization time were optimized by using HNT/IL modified PGE in combination with differential pulse voltammetry (DPV). The detection limit was achieved as 0.17 μg/mL (equals to 23.69 nM) in the linear range of 0.25–2 μg/mL miRNA-21. The selectivity of voltammetric method based on HNT/IL-PGE developed for miRNA-21 was examined in the presence of mismatch (MM) and non-complementary (NC) sequences. Because miRNA-21 is over-expressed in cancer cells, it has been tested in total RNA samples isolated from cancer cell line (breast cancer cell line, MCF-7). In the total RNA samples obtained from MCF-7, the detection limit was calculated as 0.28 μg/mL in the linear range of 1–4 μg/mL. Besides, the healthy cell line (human embryonic kidney cell line, HEK-293) was used as a control group and the results obtained by MCF-7 total RNA samples were compared to the results using HEK-293 total RNA samples in terms of miRNA-21 level.

Highly efficient and stable catalysts-covalent organic framework-supported palladium particles for 4-nitrophenol catalytic hydrogenation

A covalent organic framework (COF) was used as the support of the catalyst in this work in order to obtain an environmentally friendly catalyst with high catalytic performance, selectivity and stability for 4-nitrophenol hydrogenation. Pd tiny particles are fixed in the cavity of COF to obtain Pd/COF catalysts, which has a quite narrow particle size distribution (5.09 ± 1.30 nm). As-prepared Pd/COF catalysts (Pd loading-2.11 wt%) shows excellent catalytic performance (conversion - 99.3%, selectivity >99.0% and turnover frequency (TOF)-989.4 h−1) for 4-nitrophenol hydrogenation under relatively mild reaction conditions of reaction temperature-40 °C and reaction pressure-3.0 MPa H2, and Pd/COF catalysts have high stability. Pd/COF catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscope (TEM), high resolution TEM (HRTEM), Brunauer-Emmett-Teller (BET), scanning TEM energy-dispersive X-ray spectroscopy (STEM-EDS) elemental analysis techniques to prove that the Pd nanoparticles are highly dispersed on the COF. Pd/COF catalysts have good stability and reusability hence with certain industrial application value.

Assessment of Trace Element (Mg, Al, K and Mo) in 14 Types of Raw Herbs and Spices using SEM-EDX Analysis

Herbs and spices are multi-purposes ingredients and essential in daily life such as in cooking as well as in traditional medicines. There was a lack of information on heavy metal composition of herbs and spices in Malaysia. Therefore, this study reveals the major and trace elements of elemental compounds in 14 types of herbs and spices using the Scanning Electron Microscopy Energy Dispersive X-Ray Spectroscopy (SEM-EDX) method. The pH of most herbs and spices values are found to be in the ranges of pH 5.70 until 7.60 for herbs, while pH for spices is found to be within pH 5.26 until 7.23. A statistically eloquent relationship (r=0.91, P&lt;0.05) was found for Mg and its pH level in herbs by employing Pearson correlation. The SEM-EDX reveals the elements of carbon (C), aluminium (Al), magnesium (Mg), potassium (K) and molybdenum (Mo) are detected for the entire herbs and spices samples. C is the dominant element found at high concentration (&gt;85%) in both herbs and spices. Basil and cardamom have the most elevated amount of K with atomic percentage of 1.82% and 2.14%. Basil and ginger samples consist of more than 1.00% atomic percentage. The values of Al found in the samples of oregano (0.11%) and black pepper (0.37%). Higher amount of Mo concentration was found in ginger with an atomic percentage of 0.99%. The values obtained in the assessment are within the safe level for both herbs and spices, according to WHO.

Raman spectroscopy investigation of vibrational mode of Sb2-xMnxTe3 nanocrystals in host glass

Vibrational modes property variations of diluted magnetic semiconductor nanocrystals of Sb2xMnxTe3 grown in a glass host system were investigated. Transmission electron microscopy images and energy dispersive X-ray analysis confirm the size, interplanar distance and composition of these NCs. Electronic paramagnetic resonance spectra confirm the incorporation of manganese ions in the Sb2Te3 crystal lattice due to the six absorption lines. Moreover, changes in Mn-Mn interactions are observed as xMn-concentration increases. The Raman- and IR-active vibrational modes of quintuple layer changes of the Sb2-xMnxTe3 NCs give strong evidence of the incorporation of Mn2+ ions in Sb2Te3 NCs.

Modes of Occurrence of Critical Metal Elements (Li, REEs and Other Critical Elements) in Low-Grade Bauxite from Southern Shanxi Province, China

The low-grade bauxite in southern Shanxi Province, China is enriched in multiple critical metal elements, including Li, Ga, V, Se, and rare earth elements (REEs), which have reached the standard of comprehensive utilization as independent deposits or associated resources. Even more importantly, identifying the modes of occurrence of these critical elements is essential for designing technologies to extract critical metals from bauxite ores. This study used a combination of direct (X-ray diffraction, scanning electron microscopy–energy dispersive X-ray spectroscopy, and micro-X-ray fluorescence spectrometer), and indirect (size sieving method, float-sink experiment, and correlation analysis) methods to effectively reveal the distribution of critical elements in the different identified mineral phases. The results regarding the low-grade bauxite are as follows: Li was mainly hosted in cookeite as an independent mineral; Ga was mainly associated with diaspore; anatase is the main carrier mineral for V; REEs were present in the low-grade bauxite in multiples modes of occurrence, the most common of which were goyazite, and to a lesser extent, florencite; Se primarily occurs in sulfides. This study contributes to the development and utilization of these essential metal resources in bauxite by providing a useful reference.

AuAg Nanoparticles Grafted on TiO2@N-Doped Porous Carbon: Improved Depletion of Ciprofloxacin under Visible Light through Plasmonic Photocatalysis.

TiO2 nanoparticles (NPs) were modified to obtain photocatalysts with different composition sophistication and displaying improved visible light activity. All of them were evaluated in the photodegradation of ciprofloxacin. The band gap of TiO2 NPs was successfully tailored by the formation of an N-doped porous carbon (NPC)-TiO2 nanohybrid through the pyrolysis of melamine at 600 °C, leading to a slight red-shift of the absorption band edge for nanohybrid NPC-TiO2 1. In addition, the in-situ formation and grafting of plasmonic AuAg NPs at the surface of NPC sheets and in close contact with TiO2 NPs leads to AuAg-NPC-TiO2 nanohybrids 2–3. These nanohybrids showed superior photocatalytic performance for the degradation of ciprofloxacin under visible light irradiation, compared to pristine P25 TiO2 NPs or to AuAg-PVP-TiO2 nanohybrid 4 in which polyvinylpyrrolidone stabilized AuAg NPs were directly grafted to TiO2 NPs. The materials were characterized by transmission electron microscope (TEM), High Angle Annular Dark Field—Scanning Transmission Electron Microscopy—Energy Dispersive X-ray Spectroscopy HAADF-STEM-EDS, X-ray photoelectron spectroscopy and solid UV-vis spectroscopy. Moreover, the active species involved in the photodegradation of ciprofloxacin using AuAg-NCS-TiO2 nanohybrids were evaluated by trapping experiments to propose a mechanism for the degradation.

Influence of Dissolved Hydrogen Concentration on the Protective Property of Oxide Film of Alloy 600 Against Primary Water Stress Corrosion Cracking

Primary water stress corrosion cracking (PWSCC) of Alloy 600 has been a key issue in the field of nuclear energy. It is well known that dissolved hydrogen (DH) plays a crucial role in PWSCC initiation, and some studies showed that PWSCC initiation could be mitigated by decreasing the DH concentration. However, there is no consensus on the mechanism of the PWSCC mitigation in a low DH environment. Hence, to reveal the protective property of the passive film formed in various levels of DH, we analyzed the oxide film formed in simulated primary water at 345°C with the DH concentrations of 5 cc/kg and 30 cc/kg-H2O by electrochemical measurements (electrochemical impedance spectroscopy and Mott-Schottky test) and transmission electron microscopy (energy dispersive x-ray spectroscopy and electron energy loss spectroscopy) where the specimens of interest were tested by reverse U bend (RUB) tests, and it was confirmed that the PWSCC initiation time was longer for 5 cc/kg-H2O DH than for 30 cc/kg-H2O DH. Electrochemical measurements showed that the oxide film for the lower DH environment (5 cc/kg-H2O) had a higher electrical resistance and lower defect density than those for the higher DH (30 cc/kg- H2O). The microscopic observation indicated that the intergranular oxidation was relatively insignificant in the lower DH environment. The oxide film for both DH conditions consisted of outer oxides and inner Cr-rich barrier layer. The inner layer for 5 cc/kg-H2O DH had a higher concentration of Fe and a greater ratio of Fe3+/Fe2+ than that for 30 cc/kg-H2O DH. The results suggested that Fe3+ contributed to the formation of a less defective spinel-type structure in the inner oxide in the lower DH environment and thereby provided the alloy surface with corrosion protection. This protective oxide film prevented intergranular oxidation and led to the mitigation of PWSCC initiation in a low DH environment.

In situ growth of MnO2 on pDA-templated cotton fabric for degradation of formaldehyde

Degradation of formaldehyde (HCHO) in interior decoration has been an urgent issue due to its toxicity nature and potential threats to human health. In this work, manganese dioxide nanoparticles (MnO2 NPs) were in situ grown on the polydopamine (pDA)-templated cotton fabrics for environmentally friendly HCHO degradation applications. The morphology, elemental composition, and crystal structure of the cotton/pDA/MnO2 were characterized by scanning electron microscopy–energy dispersive X-ray spectrum, Fourier transform infrared, X-ray diffractometer and X-ray photoelectron spectroscopy, respectively. The degradation of HCHO by the as-developed cotton/pDA/MnO2 was measured in a self-made quartz reactor, and the stability of adsorption was evaluated by cyclic experiments. The results showed that the HCHO removal efficiency reached to 100% within 20 min after three cycles, suggesting that the as-prepared fabrics exhibited good stability for the degradation of HCHO. The development of MnO2 NPs coated fabrics provides new strategies in degradation HCHO in interior decoration.

Elucidation of Compositional Inhomogeneities in LiNixCoyMnzO2 by Single Particle Laser Ablation-Inductive Coupled Plasma-Mass Spectrometry

Over the many years of cathode active material research for lithium-ion batteries, LiNixCoyMnzO2 (NCM, x+y+z = 1) have emerged as one of the most promising chemistries for mass application.[1] The exact NCM elemental composition is directly linked to the material properties which in turn influence energy density, durability, safety and cost of the final products.[2] The individual contributions of Ni, Mn and Co have been heavy investigated in both industry and academia to find the best trade-offs between all properties, nowadays settling for materials with Ni contents > 80 %.[3]The composition of NCM materials is determined in the precipitation step of the mixed transition metal hydroxide precursors.[4] At laboratory scale, precursor precipitation is typically operated in batch mode. However, the precipitation in continuous stirred tank (CSTR) reactors is industrially favourable due to the higher space-time-yield, thus reducing the overall production cost. In comparison to batch-type precursors that exhibit a homogeneous µm-sized spherical particle morphology, CSTR-type precursors can be distinguished by their broad particle size distribution due to the intrinsic residence time distribution of particles in the reactor setup. Although rarely discussed, this phenomenon is accompanied by a particle-size dependent elemental composition of the precursor particles, consequently impacting the battery performance.Besides inductive coupled plasma-optical emission spectroscopy (ICP-OES) or mass spectrometry (ICP-MS) that both determine the bulk elemental composition of NCMs and their precursors, scanning electron microscopy (SEM) or transmission electron microscopy (TEM) energy dispersive X-ray (EDX) analysis can access local elemental inhomogeneities. However, both methods are tedious in both acquisition and data evaluation.In this work, an alternative method to determine the elemental composition of individual µm sized particles is presented using a laser ablation (LA) system coupled to an ICP-MS. By the example of a Ni0.91Co0.045Mn0.045(OH)2 CSTR precursor, particle size dependent elemental inhomogeneities are demonstrated. An enrichment of Ni in larger particles with a concomitant enrichment of Co and Mn in smaller particles is identified, which persists after thermal lithiation of the precursors. The results of the LA-ICP-MS analysis are cross-validated with both SEM-EDX and TEM-EDX. Furthermore, the impact of the process conditions during precipitation on the elemental inhomogeneity are elaborated by the comparison of a series of Ni0.83Co0.12Mn0.05(OH)2 precursors precipitated at varying pH. Finally, future applications of the method are proposed. G. E. Blomgren, Journal of The Electrochemical Society, 164, A5019 (2017).H.-J. Noh, S. Youn, C. S. Yoon and Y.-K. Sun, Journal of Power Sources, 233, 121 (2013).W. Li, E. M. Erickson and A. Manthiram, Nature Energy, 5, 26 (2020).H. Dong and G. M. Koenig, CrystEngComm, 22, 1514 (2020).