Wavelength Dispersive X-ray Spectroscopy Research Articles

Effects of Tooth Desensitizers on Streptococcus mutans Biofilm Formation Using a Modified Robbins Device Flow Cell System.

This study aimed to assess the antibiofilm effects of dentin desensitizers using a modified Robbins device flow cell system. The test desensitizers were Saforide, Caredyne Shield, and Clinpro White Varnish. Standardized dentin specimens were prepared from human single-rooted premolars, treated with one of the materials, and mounted on the modified Robbins device flow cell system. Streptococcus mutans biofilms were developed for 24 h at 37 °C under anaerobic conditions. Scanning electron microscopy, fluorescence confocal laser scanning microscopy, viable and total cell counts, acid production, and gene expression analyses were performed. A wavelength-dispersive X-ray spectroscopy electron probe microanalyzer was used to analyze the ion incorporations. Clinpro White Varnish showed the greatest inhibition, suggesting its suppression of bacterial adherence and transcription of genes related to biofilm formation. Saforide reduced only the number of viable bacteria, but other results showed no significant difference. The antibiofilm effects of Caredyne Shield were limited. The uptake of ions released from a material into dentin varies depending on the element. Clinpro White Varnish is effective for the short-term treatment of tooth sensitivity due to dentin demineralization. It prioritizes remineralization by supplying calcium and fluoride ions while resisting biofilm formation.

In Vitro Evaluation of Cellular Interactions with Nanostructured Spheres of Alginate and Zinc-Substituted Carbonated Hydroxyapatite.

The increasing demand for effective bone regeneration materials drives the exploration of biomaterials with enhanced bioactivity and biocompatibility, such as zinc-substituted compounds. This study investigates the in vitro cellular interactions with nanostructured spheres composed of alginate/carbonated hydroxyapatite (CHA), compared to zinc-substituted CHA (ZnCHA). This work aimed to compare the physicochemical properties and biological effects of ZnCHA and CHA on osteoblasts. ZnCHA was synthesized using a wet chemical method, followed by characterization through X-ray diffraction, Fourier transform infrared spectroscopy, total organic carbon analysis, Wavelength-dispersive X-ray spectroscopy, and BET surface area analysis to assess ion release and structural changes. Biological evaluation was conducted using cell viability, proliferation, and biomineralization assays on osteoblasts. Results showed successful incorporation of zinc and carbonate, leading to reduced crystallinity and increased surface area. Cell viability and proliferation assays indicated ZnCHA's cytocompatibility and enhanced osteoblastic activity, with increased mineralization nodules compared to CHA samples. The study concludes that ZnCHA composites are promising candidates for bone tissue engineering, demonstrating improved cytocompatibility and potential for further preclinical evaluations.

Ladle slag–based binder for the solidification/stabilization of heavy-metal-rich industrial waste

Heavy metal pollution from industrial sources is a major environmental and health hazard on a global scale. This study introduces a solidification/stabilization method of industrial waste using a waste-based, ettringite-rich solid binder from ladle slag and gypsum for the immobilization of an industrial waste material with extremely high contents of several heavy metals. The importance of sulfate and water content on the immobilization efficiency and the use of citric acid to increase the processing time of the binder were studied. The leaching of Pb, Hg, Se, As, Cd, Cu, and Ni was measured, and X-ray powder diffraction, field-emission scanning electron microscopy, and field-emission electron probe microanalysis combined with wavelength-dispersive X-ray spectroscopy were used to analyze the structure of the hardened binder and the location of the heavy metals within. The study shows that the ladle slag/gypsum binder is suitable for the solidification/stabilization of heavy-metal-rich solid industrial waste. Hg, As, Cd, Cu, and Ni were fully immobilized in all scenarios covered in the study, whereas Pb and Se showed more complicated behaviors. The main immobilization method was encapsulation, and partial Se incorporation into ettringite was observed. The presence of citric acid increased the processing time of the binder without harming the immobilization, unless combined with low sulfate content.

Decreased Metal Dusting Resistance of Ni-Cu Alloys by Fe and Mn Additions

Ni-Cu alloys are promising for application at temperatures between 400–900 °C and reducing atmospheres with high C-contents. Typically, under such conditions, metallic materials in contact with the C-rich atmosphere are degraded by a mechanism called metal dusting (MD). Ni-Cu-alloys do not form protective oxide scales, but their resistance is attributed to Cu, which catalytically inhibits the C-deposition on the surface. Adding other alloying elements, such as Mn or Fe, was found to enhance the MD attack of Ni-Cu alloys again. In this study, the effect of the Mn and Fe is divided into two affected areas: the surface and the bulk. The MD attack on binary Ni-Cu alloys, model alloys with Fe and Mn additions, and commercial Monel Alloy 400 is experimentally demonstrated. The surface electronic structure causing the adsorption and dissociation of C-containing molecules is investigated for model alloys. Analytical methods such as scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, electron probe microanalysis combined with wavelength-dispersive X-ray spectroscopy, X-ray diffraction analysis, and near-edge X-ray absorption fine structure measurements were used. The results are correlated to CALPHAD calculations and atomistic simulations combining density functional theory calculations and machine learning. It is found that the Cu content plays a significant role in the surface reaction. The effect of Mn and Fe is mainly attributed to oxide formation. A mechanism explaining the enhanced attack by adding both Fe and Mn is proposed.

Modeling and Analysis of Polarization Losses in Solid Oxide Fuel Cells with Siloxane Contamination

In this study, the degradation of the solid-oxide fuel cell (SOFC) nickel-yttria stabilized zirconia anode under decamethyltetrasiloxane (L4) contamination is examined with experiments and modeling. A model is developed for the polarization losses based on the charge transfer coefficient, α, and diffusion layer thickness, δ, and fitted to the experimental data to understand how the siloxane degrades the SOFC performance with time. The results of the model indicate that the total polarization losses increase approximately 44% over the course of the 180 min experiment at 350 mA cm−2. Activation losses dominate the polarization losses initially but decrease in their total contribution while concentration losses increase. Scanning electron microscopy (SEM) with wavelength dispersive X-ray spectroscopy (WDS) elemental mapping indicates that silicon deposition is highest at the outer edge of the anode and forms a barrier layer to fuel diffusion, increasing concentration losses. When the model is applied to other previous D4 and L4 siloxane experiments conducted over a period of 40 h, similar trends in polarization losses are observed. Polarization losses increase more rapidly with D4 compared to L4 siloxane contamination, with concentration losses increasing the fastest with both types of siloxane.

Corrosion behaviors of single-layer and double-layer nickel alloy coatings fabricated by arc spraying and high-velocity oxy-fuel

This study investigates single-layer and double-layer thermally sprayed nickel alloy coatings (bond and top coatings). Ni-5 wt% Al and Ni-20 wt% Cr were used as bond coatings, whereas highly alloyed Ni-based coatings, Hastelloy C276 or Inconel 625 were used as top coatings. Arc spraying (A) and high-velocity oxy-fuel (HVOF) techniques were used to create the coatings on a 304 stainless steel substrate. The samples were studied by performing potentiodynamic polarization tests in a 20 vol% H2SO4 solution at room temperature. The scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and wavelength dispersive X-ray spectroscopy (WDS) techniques were used to investigate the microstructure and chemical composition of the coatings. The arc sprayed coatings are composed of a lamellar microstructure with low porosities, unmelted particles, and high oxides at the intersplats. A uniform and compact coating with minimal oxides and porosity was achieved for all coatings via HVOF technique. In single-layer coatings, arc spray coating surpasses HVOF coating owing to its oxide layers, which impede sulfuric solution penetration and bolster resistance against electrolyte infiltration. Double-layer coatings, comprising a bonding layer and a top coating, using the same thermal spray method have shown to enhance corrosion resistance.

Physical simulation of the underclad heat affected zone in a reactor pressure vessel to study intergranular cracking

Underclad cracking in nuclear pressure vessels was of significant concern in the 1970s and 1980s before mitigating adjustments were made both to steel compositions and manufacturing practice. Unfortunately, the cracking mechanisms are still not well understood, and this can undermine confidence when changes to cladding operations are under consideration. In this work, Charpy-sized test coupons of 18MND5 steel were subject to a range of thermal cycles that can be experienced by the substrate immediately adjacent to the interface with the overlay. The Charpy test results are considered in combination with analysis of the samples through field emission gun (FEG) scanning electron microscopy (SEM) and wavelength dispersive X-ray spectroscopy (WDXS). The findings suggest that the heat affected zone subject to the coarse grained plus intercritical thermal cycle, before post weld heat treatment, has a peculiar and potentially brittle microstructure. However, in a steel with no obvious macrosegregation, no clear evidence of intergranular cracking in the early stages of the post weld heat treatment could be found. The second part of the work focuses on the effects of segregation regions in large forgings, more specifically ghost lines, on the tendency for underclad cracking. Ghost line regions that subsequently form a coarse grained heat affected zone (CGHAZ), and are then heated to just under the A1 temperature, seem to be the most prone to intergranular cracking. Cracking susceptibility appears to be associated with elevated concentrations of alloying and impurity elements at grain boundaries.

Phase Analysis and Measurement of Local Carbon Contents in Hypoeutectic Alloys in the System Fe-C-B-Cr-W

Cold work tool steels of the Fe‑0.4C-1B-Cr alloy system use the element boron (B) for hard phase formation. B should facilitate a reduction in the contents of carbide-forming elements and carbon (C) to the extent that C is used exclusively for martensitic hardening, while allowing the practical utilization of hard borides as hard phases. The formation of carboborides stands in the way of this concept. To further develop the alloying system, an interaction of the alloying elements tungsten (W) and C during solid-state microstructure formation during heat treatment is investigated. The main objective is to investigate the influence of hardening as well as solution annealing on the solution state of C in the martensitic matrix in different W‑alloyed high B‑content cold work tool steels. For this purpose, two laboratory melts of Fe‑0.4C-1B‑2.5Cr‑W are cast with a W content of 2 and 9 mass%, swaged, austenitized at 1100 °C for varying time steps, and quenched. A microstructure and phase analysis is carried out by means of scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD). Furthermore, the local C contents of the martensitic matrix and hard phases are measured by wavelength dispersive X‑ray spectroscopy (WDS). The results are discussed considering thermodynamic equilibrium calculations. It is shown that the addition of W leads to the eutectic formation of W‑rich carboborides, which are thermodynamically stable at austenitization temperature. However, high B contents in the carboborides lead to a significant reduction in the boride content of these alloys, which results in significant differences to the thermodynamic calculations.

Antibiofilm Properties and Demineralization Suppression in Early Enamel Lesions Using Dental Coating Materials.

This study aimed to investigate the effects of dental coating materials on Streptococcus mutans biofilm formation. The test materials were PRG Barrier Coat (PRG), BioCoat Ca (BioC), and FluorDental Jelly (FluorJ). Bovine enamel specimens were demineralized to mimic early enamel lesions. The biofilm was developed on a specimen treated with one of the materials by using a modified Robbins device flow-cell system. Scanning electron and fluorescence confocal laser scanning microscopy, viable and total cell counts, and gene expression assessments of the antibiofilm were performed. Ion incorporation was analyzed using a wavelength-dispersive X-ray spectroscopy electron probe microanalyzer. All materials allowed biofilm formation but reduced its volume. FluorJ was the only material that inhibited biofilm accumulation and had a bactericidal effect, revealing 0.66 log CFU in viable cells and 1.23 log copy reduction in total cells compared with the untreated group after 24 h of incubation. The ions released from PRG varied depending on the element. BioC contributed to enamel remineralization by supplying calcium ions while blocking the acid produced from the biofilm. In summary, the dental coating materials physically prevented acid attacks from the biofilm while providing ions to the enamel to improve its mechanical properties.

A new neodymium complex on renewable magnetic biochar nanoparticles as an environmentally friendly, recyclable and efficient nanocatalyst in the homoselective synthesis of tetrazoles.

Inexpensive, stable, selective, and recyclable nanocatalysts, waste regeneration, and utilization of safe and available solvents are of interest and important factors in laboratory science and industrial applications of green chemistry. Therefore, herein, biochar nanoparticles (BNPs) were synthesized through chicken manure pyrolysis as a novel method for waste recycling. Then, in order to improve their recyclability, the obtained BNPs were magnetized using magnetic nickel nanoparticles. Then, the surface of the biochar magnetic nanoparticles (BMNPs) was modified by (3-chloropropyl)trimethoxysilane (3-CPTMS) and further a novel neodymium Schiff-base complex was immobilized on the surface of the modified BMNPs, denoted as Nd-Schiff-base@BMNPs. The obtained supported neodymium complex was used as a practical, selective, biocompatible, commercial, and reusable heterogeneous nanocatalyst. The biochar support of this nanocatalyst was formed from pyrolysis of chicken manure; therefore, it is cheap, economically viable, green and also compatible with the principles of green chemistry. Nd-Schiff-base@BMNPs acts selectively in organic reactions and also it can easily be recovered using an external magnet and reused, which is compatible with the principles of green chemistry. This nanocatalyst was characterized by wavelength-dispersive X-ray spectroscopy (WDX), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma (ICP), and N2 adsorption-desorption (BET method) techniques. In the next step, the catalytic utilization of Nd-Schiff-base@BMNPs was investigated in the homoselective synthesis of 5-substituted 1H-tetrazole compounds from [3 + 2] cycloaddition of sodium azide (NaN3) and organo-nitriles in PEG-400 as a green solvent. Utilizing PEG-400 as a solvent offers various advantages, e.g. cheap, readily available, and environmentally friendly solvent as well as rapid separation and high purity of products. Therefore, this work is fully compatible with the principles of green chemistry.

Monitoring Copper Ion Leaching from a Metalloporphyrin-Based Cathode for Rechargeable Magnesium Batteries

Great efforts are being undertaken to characterize the fundamental processes of solid electrolyte interphase (SEI) formation, degradation, and initial conditioning steps of battery electrode materials, including organic electrode materials.[1] Imaging techniques, such as focused ion beam / scanning electron microscopy (FIB/SEM) tomography in combination with element mapping using energy- and wavelength-dispersive X-ray spectroscopy are employed to gain insight into distribution, interconnectivity, and porosity of active materials as well as electrolyte penetration and their influence on degradation processes after longer cycling times.[2] Additionally, electrochemical impedance spectroscopy[3] and anodic stripping voltammetry[4] are used to shed light on those processes. The metalloporphyrin-based material [5,15-bis(ethynyl)-10,20-diphenylporphinato]copper(II) (CuDEPP) has been used as an interesting material for cathodes and anodes of various battery chemistries. These materials undergo initial self-conditioning by electro-polymerization for monovalent ions. With respect to multivalent ions, like magnesium, this polymerization is far less pronounced and an exchange of the copper from the CuDEPP by magnesium ions appears to be occurring.[5] Gaining insight into this trans- or demetallation process induced by parameters like the electrochemical driving force during galvanostatic cycling is a complex analytical challenge.We report the use of Hg ultramicroelectrodes and anodic stripping voltammetry as a sensitive strategy to detect copper ion leaching from metalloporphyrin-based CuDEPP composite electrodes. We demonstrate in-situ/intermittent monitoring of copper ion release during the initial self-conditioning step of the active material while galvanostatic cycling of the battery electrode in dimethoxy ethane. This method could be used to assess the release of an ionic species from complex systems, like composite battery electrodes.

RbEr2AsS7: A Rubidium-Containing Erbium Sulfide Thioarsenate(III) with (S2)2− Ligands According to RbEr2S(S2)[AsS2(S2)

The new rubidium-containing erbium sulfide thioarsenate(III) with the structured formula RbEr2S(S2)[AsS2(S2)] was obtained from the syntheses of elemental erbium (Er), arsenic sesquisulfide (As2S3) and rubidium sesquisulfide (Rb2S3) with elemental sulfur (S) at 773 K as transparent, orange, needle-shaped crystals. RbEr2AsS7 crystallizes monoclinically in the space group C2/c with a = 2339.86(12) pm, b = 541.78(3) pm, c = 1686.71(9) pm and β = 93.109(3) ° for Z = 8. The crystal structure features complex [AsS2(S2)]3− anions with two S2− anions and a (S2)2− disulfide dumbbell coordinating end-on as ligands for each As3+ cation. Even outside the ligand sphere of As3+, S2− and (S2)2− can be found as sulfide anions. Two distinct Er3+ cations are surrounded by either nine or seven sulfur atoms. The [ErS9] polyhedra are corner- and face-connected, while the [ErS7] units share common edges, both building chains along [010]. These different chains undergo edge connectivity with each other, resulting in the formation of corrugated layers, which are held together by Rb+ in chains of condensed [RbS9] polyhedra. So, a three-dimensional network is generated, offering empty channels along [010] apt to take up the As3+ lone-pair cations. Wavelength-dispersive X-ray spectroscopy verified a molar Rb:Er:As:S ratio of approximately 1:2:1:7 and diffuse reflectance spectroscopy showed the typical f–f transitions of Er3+, while the optical band gap was found to be 2.42 eV.

Identification method for dental alloy type using a cosine similarity program: A preliminary investigation.

Although dental evidence is frequently used for the identification of unidentified persons, information about the many types of alloys used in prosthetics is not utilized. If the type of alloy can be identified from a small amount of material, the scope of the search could be narrowed. In this experiment, a method was investigated for identifying the alloy type using 3 kinds of cutting points (a white point and 2 types of silicone points). Wavelength-dispersive X-ray spectroscopy (WDS) was used for elemental analysis. The elements were translated into multidimensional vectors, and the cosine similarity was calculated to compare vectors of the WDS results and vectors of the official data of alloys. According to the results, cosine similarity showed a concordance of more than 0.8. The developed program is expected to be useful as a method for identifying alloy types using only a small amount of grinding dust.

A comparative study of in-situ alloying in laser powder bed fusion for the stainless steel X2CrNiMoN20-10-3

This paper compares, for the first time, laser powder bed fusion (PBF-LB/M) processing of a powder mixture (PM), also known as in-situ alloying, with that of a pre-alloyed (PA) powder from gas atomization with the same chemical composition, using the example of X2CrNiMoN20-10-3 ferritic-austenitic stainless steel. The focus is on the differences in the microstructure formation mechanisms during PBF-LB/M between PM and PA using different energy inputs, in order to gain new insights into the process transferability of in-situ alloying to the processing of pre-alloyed powders. The microstructure investigations are carried out using electron backscattered diffraction (EBSD), energy dispersive (EDS) as well as wavelength dispersive X-ray spectrometry (WDS), X-ray diffraction (XRD) and magneto-inductive method (Feritscope®). The microstructures of samples produced from PM and PA differ significantly in terms of the resulting ferritic and austenitic phase fractions, so that a ferritic-austenitic microstructure forms for PM, while the PA is predominantly austenitic. The differences are mainly based on the increased chemical inhomogeneities for the PM in comparison to the PA state, which are discussed based on EDS map analysis through spatial statistics. With increasing energy input, the chemical homogeneity of the PM approaches that of the PA, but it cannot reach it even with maximum energy input. The formation of a ferritic-austenitic microstructure in the case of the PM leads to the formation of a finer microstructure compared to single-phase PA steel resulting in higher hardness of PBF-LB/M-built PM.

Role of oxygen potential in dopant solubility in ferrite magnets: Enhanced Zn solubility and magnetization in La–Zn co-substituted magnetoplumbite-type strontium ferrite

To improve the performance of magnetoplumbite-type (M-type) AFe12O19 (A = Sr, Ba, Pb,…) hard ferrite magnets, such as the remanent magnetization and the coercivity, it is effective to dope transition metal elements at the Fe site. Substitution of nonmagnetic Zn, which preferentially occupies a minority-spin site in the ferrimagnets, is expected to increase magnetization. However, the solubility of Zn is limited to approximately 2–3% of Fe when synthesized in air. The solubility of divalent transition-metal substituents achieved by simultaneous substitution with trivalent cations on the A-site is often limited due to the auto reduction of Fe3+ to Fe2+. In this study, La–Zn co-substituted M-type strontium ferrites, Sr1−xLaxFe12−yZnyO19, were synthesized under different oxygen pressures of pO2 = 0.2, 1, and 10 atm, and the phase equilibrium and chemical composition were established by X-ray diffraction and wavelength dispersive X-ray spectroscopy. At pO2 = 10 atm, Sr-free La–Zn co-substituted ferrite, LaFe11.25Zn0.75O19, and single phases with actual compositions (x, y) = (0.42, 0.33) and (0.50, 0.45) were obtained for the first time. The single-phase samples exhibited a 5–9% higher saturation magnetization compared to non-doped SrFe12O19 at room temperature. Together with the coercivity enhancement by Co2+ substitution, oxygen potential control is a promising strategy to tune both coercivity and magnetization in future ferrite magnets.

Development of a functional hardness gradient in WC-TiC-Co cemented carbide during gradient sintering

In this study two functionally graded cemented carbide samples with gradients in both composition and grain size have been produced and studied. The two samples are manufactured by local addition of TiC to a pressed WC-Co green body prior to sintering. The two samples differ only by the in-going WC particle size, where one sub-micron and one coarse WC particle size is used. The Ti, Co, and C concentration profiles are analysed using energy−/ and wavelength-dispersive X-ray spectroscopy; Vickers hardness profiles are also measured. Furthermore, the measured experimental concentration profiles are compared with diffusion simulations using the DICTRA software. The concentration and hardness profiles show a similar trend for both samples with decreasing Ti and C concentrations while Co concentration increases with distance from the applied TiC layer. The composition gradient affects the number of stable phases and the WC grain size. Furthermore, there are distinct differences between the samples with different initial WC particle size. The sample with an initially finer WC particle size has a shorter gamma-phase zone and the difference in WC grain size across the gradient is larger as compared to the sample with an initially coarser WC particle size. Finally, abnormal grain growth occurs in both samples but it is suppressed with increasing Ti concentration.

Integrated property predictions during casting and heat treatment of Al-Si-Cu-Mg alloys by precipitation simulation

The production and manufacture of aluminium castings typically involves multiple heat treatment process steps. Simulation tools are very useful to help predict the evolution of mechanical properties, to improve process parameters and as a guideline for casting design. In this study, a kinetic model, based on Nucleation and Growth Theory (CNGT), was developed and implemented for modelling heat treatment in a casting process simulation tool. Starting from information generated from the simulation of solidification and cooling of the casting, simulation was carried out to predict further precipitation behaviour of multiple Cu or Mg-Si -containing phases during solution treatment, quenching, and artificial ageing processes in heat treatment of Al alloys. Model validation was carried out within the research cluster “Advance Metals and Processes” in Aachen, Germany. Heat treatments were performed on two different Al-Si-Cu-Mg alloys with different quench methods and at different ageing temperatures. Experimental investigations including atom probe, wavelength dispersive X-ray spectroscopy, and tensile tests were conducted to calibrate and validate the model. The simulations showed good agreement for the studied conditions and a promising modelling approach for integrated simulation of casting and heat treatment for industrial applications.

Conventional s-wave superconductivity in the non-centrosymmetric compounds Re3W, Re3W0.5Nb0.5, and Re3W0.5Ta0.5

We carried out an investigation of the structural and superconducting properties of Re3W1−xMx alloys, which can crystallize in both a centrosymmetric (CS) hexagonal, and a non-centrosymmetric (NCS) cubic α-Mn phase. The superconducting transition temperatures (Tc) of the CS and NCS phases in pure Re3W are ∼ 9.1 and ∼ 7.7 K, respectively. While boules fast cooled from the melt have a mixture of CS phases, the NCS phase can be stabilized upon annealing at very high temperatures (∼ 1700 °C), or upon the partial substitution of the transition metals M = Ta, or Nb for W. X-ray diffraction and wavelength dispersive X-ray spectroscopy (WDS) data suggest that the optimal composition for the formation of the α-Mn phase directly from the melt in Re3W1−xMx is x ≈ 0.5. A detailed study of the superconducting properties of the Re3W1−xMx solid solutions was carried out by means of measurement of magnetization, ac magnetic susceptibility, electrical transport, and low temperature specific heat. As the M content is increased, the superconducting critical temperature Tc progressively decreases, though the overall superconducting properties remain similar to those of the parent NCS Re3W compound. The partial substitution at the W site does not seem to affect the pairing mechanism. Given the exponentially vanishing character of the electronic specific heat Ce(T) at low temperatures, the superconducting behavior of the NCS alloys is consistent with a nodeless, s-wave superconducting gap symmetry in all NCS samples. These findings add the pseudo-binary Re-M-W systems to the small roll of NCS materials where the pairing symmetry of the superconducting state can be explored.

A new samarium complex of 1,3-bis(pyridin-3-ylmethyl)thiourea on boehmite nanoparticles as a practical and recyclable nanocatalyst for the selective synthesis of tetrazoles

Boehmite is a natural and environmentally friendly compound. Herein boehmite nanoparticles were primarily synthesized and, then, their surface were modified via 3-choloropropyltrimtoxysilane (CPTMS). Afterwards, a new samarium complex was stabilized on the surface of the modified boehmite nanoparticles (Sm-bis(PYT)@boehmite). The obtained nanoparticles were characterized using thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDS), Brunauer–Emmett–Teller (BET), wavelength dispersive X-ray spectroscopy (WDX), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), Inductively coupled plasma mass spectrometry (ICP-MS), dynamic light scattering (DLS), and X-ray diffraction (XRD) pattern. Sm-bis(PYT)@boehmite was used as an environmentally friendly, efficient, and organic–inorganic hybrid nanocatalyst in the homoselective synthesis of tetrazoles in polyethylene glycol 400 (PEG-400) as a green solvent. Notably, Sm-bis(PYT)@boehmite is stable and has a heterogeneous nature. Thus, it can be reused for several runs without any re-activation.

Laser-assisted reduction of iron ore using aluminum powder

This study reports on the laser-assisted reduction of iron ore waste using Al powder as a reducing agent. Due to climate change and the global warming situation, it has become of paramount importance to search for and/or develop green and sustainable processes for iron and steel production. In this regard, a new method for iron ore utilization is proposed in this work, investigating the possibility of iron ore waste reduction via metallothermic reaction with Al powder. Laser processing of iron ore fines was performed, focusing on the Fe2O3–Al interaction behavior and extent of the iron ore reduction. The reaction between the materials proceeded in a rather intense uncontrolled manner, which led to the formation of Fe-rich domains and alumina as two separate phases. In addition, a combination of Al2O3 and Fe2O3 melts, as well as transitional areas such as intermetallics, was observed, suggesting the occurrence of incomplete reduction reaction in isolated regions. The reduced iron droplets were prone to acquire a sphere-like shape and concentrated mainly near the surface of the Al2O3 melt or at the interface with the iron oxide. Scanning electron microscopy, energy-dispersive x-ray spectroscopy, and wavelength-dispersive x-ray spectroscopy analyses were employed to analyze the chemical composition, microstructure, and morphological appearances of the reaction products. High-speed imaging was used to study the process phenomena and observe differences in the movement behavior of the particles. Furthermore, the measurements acquired from x-ray computed microtomography revealed that approximately 2.4% of iron was reduced during the laser processing of Fe2O3–Al powder bed, most likely due to an insufficient reaction time or inappropriate equivalence ratio of the two components.