Dispersive Spectroscopy Electron Research Articles

Overcoming the thermodynamic barrier of alloying 2D transition metal dichalcogenides

Alloying of two-dimensional (2D) transition metal dichalcogenides (TMDs) enables modulation of their energy structure and bandgap, and thus, is crucially important for their integration into optical and electrooptical devices. However, achieving high yield and efficient alloying is often challenging due to the thermodynamic preference of one of the components over the other. Here, we develop a process for growing Mo1−xWxS2 alloys. While common chemical vapor deposition (CVD)-based growing techniques give limited alloying due to the thermodynamic dominance of MoS2 over WS2, we present here an efficient means to achieve high-yield alloying via a two-step CVD process. In this process, first, we grew monolayer WS2 flakes on a substrate, followed by the nucleation-diffusion second step. In this step, MoS2 nucleates mostly on the edges of the WS2, followed by diffusion of the Mo atoms into the flakes to achieve Mo1−xWxS2 alloys. Indeed, we obtained a large amount of alloy growth with different atomic compositions (i.e., various values of x). We employed several analysis methods, including Raman, photoluminescence, x-ray photoelectron spectroscopy, and electron dispersive spectroscopy, to characterize the properties of the grown alloys. These analyses demonstrate the transition from WS2- (x→1) to MoS2-like (x→0) behaviors, through alloy behavior (0<x<1), which combines the properties of both materials and presents a homogenous distribution of the diffused atoms. We also showed that controlling the diffusion time can efficiently determine the average atomic composition of the alloys. This work, therefore, overcomes the inherent thermodynamic barrier that limits the large-scale synthesis of TMD alloys, and thus, it paves the path toward their integration into advanced optoelectronic tunable bandgap applications.

Structural, magnetic, and thermal properties of nanocrystalline (Fe55Cu20Al25)90B10 alloy processed by mechanical alloying

In this study, we investigate the structural and magnetic properties of nanocrystalline (Fe55Cu20Al25)90B10 powders produced by mechanical alloying. We employ various characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron dispersive X-ray spectroscopy (EDS), and vibrating sample magnetometry (VSM) to analyze these properties. The XRD analysis reveals that after 80 h of milling, the powders undergo a transformation, resulting in the formation of a bcc-iron-based solid solution structure. After 16 h of milling, the average grain size is about 8.1 nm. Additionally, the maximum saturation magnetization reaches around 100.85 emu/g. The annealed sample exhibits structural ordering, as evidenced by the presence of Fe and Cu crystal phases, along with an increase in coercivity. The prepared alloy exhibits soft magnetic properties compared to previously investigated mechanically alloyed FeAl-based powders.

Qualitative study of carbides in liquid phase sintered M3:2 high speed steel

The microstructure of liquid phase sintered M3:2 high speed steel and the effect of adding carbon and silicon on the microstructure was characterized by scanning electron microscopy, dispersive spectrometry, and X-ray diffraction. Various types of carbides were formed depending on the added carbon and/or silicon, the sintering atmosphere and the cooling rate. The microstructure of sintered M3:2 high speed steel samples in vacuum conditions without the addition of Si and graphite is composed mainly of MC and M6C carbides inside cells and primarily at cell boundaries. The M2C eutectic carbides in these samples were formed at cell boundaries and their amounts and morphology depends on the cooling rate. Sintered samples in N2 atmosphere with added carbon and silicon, M6C eutectic and M7C3 eutectic carbides were dominantly formed while carbonitrides were formed in smaller amounts.

Enhanced photocatalytic abilities of innovative NbTaZrMoW high-entropy alloys (HEAs): a comparative analysis with its high entropy oxide (HEO) counterpart

The photocatalytic performance of high entropy alloy (HEA) and its oxide form (high entropy oxide, HEO) have been evaluated in this study. The HEA, composed of Nb, Ta, Zr, Mo, and W powders, was synthesized through a mechanical alloying process for 120 h. This process was carried out under a high-purity Ar atmosphere to prevent oxidation. Subsequently, the HEA was converted into HEO via a mechano-thermal oxidation method 900 °C for 12 h. The photocatalytic activity of both oxidized and non-oxidized samples was systematically evaluated by degradation of methyl blue (MB) under UV irradiation. Electron dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used to investigate the structural and chemical features of the alloys. Furthermore, BET surface area analysis and Zeta potential measurements were conducted to understand the alloys’ surface properties and stability in aqueous solutions. The results showed that the HEA has a remarkable photodegradation performance of around 58.77% which is two times higher than that observed with the HEO.Graphical abstract

Comparison of different approaches to texturing monocrystalline silicon wafers for solar cell applications

Texturing the surface of crystalline silicon wafers is a very important step in the production of high-efficiency solar cells. Alkaline texturing creates pyramids on the silicon surface, lowering surface reflectivity and improving light trapping in solar cells. This article provides a comparative evaluation of various wet texturing methods using alkaline solutions with or without additives commonly known as surfactants. One method uses sodium hydroxide (NaOH) and isopropyl alcohol (IPA) to create a surface with a height of about 4.5 μm by texturing for about 30 min, while the other method uses potassium hydroxide (KOH) and other additions known as additives. Texturing was performed using chemicals for only 15 min to create a surface shape with a height of approximately 3.5 μm. Additionally, the two solutions showed reflectance of 8.01 % or 12.1 % in 400–1100 nm, respectively. Both processes used alkaline etching at 80 °C for saw damage removal (SDR) before texturing. These processes have also been investigated in terms of removing potential organic contaminants from surfaces. Characterization techniques used throughout the investigation included optical microscopy, surface reflectance measurements, scanning electron microscopy (SEM), and electron dispersive spectroscopy (EDS). The purpose of this study is to confirm through experiments which texturing techniques are more suitable for mass production and to develop time- and cost-effective texturing techniques for industrial production of high-throughput, high-efficiency solar cells.

Isothermal reduction and comparative analysis of reaction kinetics of sponge iron produced from hematite-charcoal reaction using non-contact direct reduction method

The challenge of making sponge iron, or direct reduced iron (DRI), is hard to overstate. These are a key feed for metallurgical operations while iron extraction sets these limits, which include scarcity of metallurgical coke, poor environmental impact, and high production cost. Thus, the non-contact direct reduction process of DRIs has the potential to significantly reduce carbon deposition and CO2 emission from the ironmaking process. This work produced sponge iron from commercially acquired hematite ore using an alternative reducing agent (i.e. charcoal) under specified isothermal conditions. Comparative analysis of reaction kinetics models including Ginstein−Brounshtein and Shrinking core models was also performed to ascertain the resistances that control the reaction rate for reduction degree up to 98.1%. The reduction kinetics were found to be described by reaction control time and activation energies based on a shrinking core model as the reduction time lasted for 120 min at temperatures 843–1273 K. At temperatures above 973–1073 K, the rate-limiting step was found to be solely an interfacial chemical reaction process, with an apparent activation energy of 196.1 kJ/mol. In addition, a slowing trend was observed for iron ore sample sizes 10–20 mm as a result of ash layer infiltration around the inner-core structure of the DRI metal matrix. The DRI morphological characteristics were performed using Scanning Electron Microscopy (SEM) and Electron Dispersive Spectrometry (EDS) to ascertain the mineralogical and morphological properties of the DRI samples. The XRF analysis confirms that the raw iron ore sample is hematite. Its iron content is 70.04% metallic iron (TFe) which has 83.59% Fe2O3 The SEM/EDS image also revealed the presence of micropores on the DRI morphology. This indicates that the reduction ratio and swelling extent rise with the temperature and time. This happens for all DRI sizes. However, the EDS result confirms the presence of gangue elements within the DRI metal matrix and mineralogical structure. The DRI contains very high silicon content up to 33.90%. So, a fluxing experiment is needed using limestone (CaCO3) or quicklime (CaO) quicklime to remove gangue (silicate, aluminate) from the DRI matrix. At the set reduction temperatures, the largest metallization degree of 93.05% at 1273 K for a reduction time of 120 min was achieved. This showed that the overall reduction process still follows the expected chronological order since the NDR process uses CO gas from preheated charcoal. This makes DRI be produced from raw hematite under non-contact reduction bases. Therefore, the NDR technique offers a viable option for sponge iron production in modern-day iron and steelmaking processes.

Effect of oxidation on radiation shielding capacity of ZrNbTaMoW Refractory High Entropy Alloys (RHEA) for nuclear reactor applications: Experimental and theoretical assessment

This study presents the production and comprehensive assessment of a Refractory High Entropy Alloy (RHEA) with a ZrNbTaMoW composition for possible usage nuclear reactor applications. The alloy was synthesized using the mechanical alloying (MA) method, and its radiation properties were examined. Elemental powders of Zr, Nb, Ta, Mo, and W were utilized in equimolar quantities during the 120-hour MA process, conducted under a high-purity Ar atmosphere to prevent oxidation. The obtained HEA was then subjected to a mechano-thermal process to transform it into Refractory High-Entropy Oxide (RHEO) for comparing their radiation-shielding performance under oxide conditions. The characterization of the produced alloys through X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron dispersive spectroscopy (EDS). The photon shielding parameters of the alloys were experimentally obtained for various energies emitted from a 133Ba radioactive source, employing a Canberra UltraLEGe semiconductor detector. Furthermore, theoretical calculations were performed to validate the experimental data and to evaluate the alloys' photon shielding capabilities comprehensively. For this purpose, Phy-X/PSD software was employed to determine mass attenuation coefficients, half-value layer, effective atomic number, and effective electron density. Fast neutron absorption capabilities were determined through the calculation of average absorption cross-sections in the 2–12 MeV energy range. The results showed that the oxidation process significantly diminished the photon absorption capacity of RHEA.

Origin and modern microbial ecology of secondary mineral deposits in Lehman Caves, Great Basin National Park, NV, USA.

Lehman Caves is an extensively decorated high desert cave that represents one of the main tourist attractions in Great Basin National Park, Nevada. Although traditionally considered a water table cave, recent studies identified abundant speleogenetic features consistent with a hypogenic and, potentially, sulfuric acid origin. Here, we characterized white mineral deposits in the Gypsum Annex (GA) passage to determine whether these secondary deposits represent biogenic minerals formed during sulfuric acid corrosion and explored microbial communities associated with these and other mineral deposits throughout the cave. Powder X-ray diffraction (pXRD), scanning electron microscopy with electron dispersive spectroscopy (SEM-EDS), and electron microprobe analyses (EPMA) showed that, while most white mineral deposits from the GA contain gypsum, they also contain abundant calcite, silica, and other phases. Gypsum and carbonate-associated sulfate isotopic values of these deposits are variable, with δ34SV-CDT between +9.7‰ and +26.1‰, and do not reflect depleted values typically associated with replacement gypsum formed during sulfuric acid speleogenesis. Petrographic observations show that the sulfates likely co-precipitated with carbonate and SiO2 phases. Taken together, these data suggest that the deposits resulted from later-stage meteoric events and not during an initial episode of sulfuric acid speleogenesis. Most sedimentary and mineral deposits in Lehman Caves have very low microbial biomass, with the exception of select areas along the main tour route that have been impacted by tourist traffic. High-throughput 16S rRNA gene amplicon sequencing showed that microbial communities in GA sediments are distinct from those in other parts of the cave. The microbial communities that inhabit these oligotrophic secondary mineral deposits include OTUs related to known ammonia-oxidizing Nitrosococcales and Thaumarchaeota, as well as common soil taxa such as Acidobacteriota and Proteobacteria. This study reveals microbial and mineralogical diversity in a previously understudied cave and expands our understanding of the geomicrobiology of desert hypogene cave systems.

Synthesis and Antibacterial Activity of Ultrasmall Silver Nanoparticles by Pulsed Laser Ablation in Deionized Water

Background: The main objective of this work is the synthesis and evaluation of silver nanoparticles (Ag NPs) by using pulsed laser ablation of a silver (Ag) target in deionized water and examining their antibacterial activity. Methods: Colloidal solutions of silver nanoparticles were prepared with different pulsed laser energies (620, 880, and 1000) mJ of wavelength 1064 nm and frequency 10 Hz. To determine their structure, optical, morphology, elemental composition, and infrared spectra, the synthesized Ag NPs were characterized using various high-throughput analytical techniques such as (UVVis) spectroscopy, transmission electron microgram (TEM), electron dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectra, and Zeta potential. Results: The results show that the properties of synthesized Ag NPs depend much more on the laser energy. The laser energy can be used to control the properties of the prepared nanoparticles. Uniform distributions of spherical ultrasmall Ag NPs with an average size of (3) nm were obtained suspended in deionized water, which is the most effective size for antibacterial activity. However, the result indicated that the ablated Ag NPs were stable for 4 months in deionized water. The antibacterial activity of the colloidal solution of synthesized Ag NPs against Gramnegative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria was then examined using the agar-well diffusion method. Conclusion: It was found that the prepared nanoparticles exhibited strong activity against E. coli and S. aureus bacteria growth. The average zones of inhibition of Ag NPs were found to be about (26) mm for E. coli and (32) mm for S. aureus bacteria.

Electrochemical charge storage performance of (Mn, Ni, Mo, Co, Fe)3O4 high entropy oxide nanoparticles produced via thermal plasma route

Highly complex high entropy metal oxides (HEOs) have several unique characteristics, such as more active sites and material stability that improve the electrochemical charge storage capacity. In this study, HEOs (Mn, Ni, Mo, Co, Fe)3O4 nanoparticles were synthesized using a thermal plasma route and its electrochemical energy storage performance was studied with two distinct electrolytes such as 1 M KOH and NaOH. The X-ray diffraction analysis revealed the phase pure spinel structured HEOs with crystalline size ranging from 13 to 29 nm. Scanning electron microscopy and electron dispersive X-ray spectroscopy results revealed the quasi-spherical morphology and uniform distribution of constitutional cations in the as-synthesized HEOs. The X-ray photoelectron spectroscopy results identified the oxidation states of cations in spinel HEOs. The charge/discharge studies of as-synthesized HEOs showed a specific capacitance of 215 F g-1 /26.9 mAh g-1 at a current density of 2 A g-1 in 1 M KOH electrolyte which is 156 % greater than 1 M NaOH electrolyte. Furthermore, a high capacitance retention of 91 % was achieved after completing 3000 cycles at 10 A g-1 current density which indicates that the HEOs have excellent charge/discharge reversibility. Electrochemical impedance spectroscopy revealed that the solution and charge transfer resistances of HEOs electrodes were 1.04 and 3.2 Ω, respectively. This novel synthesis strategy attempts to overcome the difficulties experienced by established methods for bulk manufacture of phase pure HEOs since thermal plasma method is a rapid and a single-step approach for the bulk production of nanomaterial.

Analysis and Characterization of Composites for their potential use in Disc Brake Pad

Brake pads are crucial for vehicle safety, converting kinetic energy to halt motion. They come in types like organic, semi-metallic, ceramic, and metallic. Beyond automotive, brake pads find application in industries such as aerospace, railways, manufacturing, and wind energy for controlled deceleration and safety. This study is primarily concerned with the quality and appropriateness of ceramic brake pads for automotive applications, which are an essential aspect of braking systems for vehicles. The performance characteristics of ceramic brake pads are well established, and this study explores the variables affecting their quality. Under high pressure, brake pad samples are prepared in the study using Powder Metallurgy (PM), which guarantees superior mechanical qualities by removing interface bonding problems. The samples are then sintered at 2850. Hardness, temperature resistance, wear resistance, and Electron Dispersive Spectroscopy (EDS) analysis are all included in the evaluation to ascertain the make-up and distribution of the materials in the brake pad. EDS sheds light on the degree of sintering and the presence of reinforcements. Heat resistance is evaluated using controlled thermal testing, while wear resistance and hardness are determined through Rockwell hardness testing and wear tests, respectively. These measurements are validated for use in automotive disc braking systems for vehicles and motorcycles. The findings are more reliable thanks to statistical analysis done with MINITAB. The study highlights research gaps in environmentally friendly materials, emerging technology impacts, and long-term brake pad durability.

Analysis and Characterization of Composites for their potential use in Disc Brake Pad

Brake pads are crucial for vehicle safety, converting kinetic energy to halt motion. They come in types like organic, semi-metallic, ceramic, and metallic. Beyond automotive, brake pads find application in industries such as aerospace, railways, manufacturing, and wind energy for controlled deceleration and safety. This study is primarily concerned with the quality and appropriateness of ceramic brake pads for automotive applications, which are an essential aspect of braking systems for vehicles. The performance characteristics of ceramic brake pads are well established, and this study explores the variables affecting their quality. Under high pressure, brake pad samples are prepared in the study using Powder Metallurgy (PM), which guarantees superior mechanical qualities by removing interface bonding problems. The samples are then sintered at 2850. Hardness, temperature resistance, wear resistance, and Electron Dispersive Spectroscopy (EDS) analysis are all included in the evaluation to ascertain the make-up and distribution of the materials in the brake pad. EDS sheds light on the degree of sintering and the presence of reinforcements. Heat resistance is evaluated using controlled thermal testing, while wear resistance and hardness are determined through Rockwell hardness testing and wear tests, respectively. These measurements are validated for use in automotive disc braking systems for vehicles and motorcycles. The findings are more reliable thanks to statistical analysis done with MINITAB. The study highlights research gaps in environmentally friendly materials, emerging technology impacts, and long-term brake pad durability.

Corrosion inhibition of martensitic stainless steel by sodium benzoate in acidic medium: Solanum tuberosum extract as surfactant

Research on corrosion inhibitor efficacy has been seen as essential to enhancing the robustness of martensitic stainless steel (MSS), which finds use in a variety of industrial settings. Thus, the aim of this study is to examine the inhibitory efficacy of sodium benzoate with solanum tuberosum (potato) extract as surfactant in a 0.5 M HCl solution for MSS. The techniques of electrochemical measurements and weight loss were adopted for the MSS samples cut into corrosion coupons and submerged in 0.5 M HCl solution at room temperature. A scanning electron microscopy equipped with an electron dispersive x-ray spectroscopy (SEM-EDS) was utilized for the morphology analyses of the samples. From the obtained results, the maximum inhibition efficiency of 32.58 % was recorded at 1.0 M inhibitor concentration, indicating that sodium benzoate is an effective corrosion inhibitor. It was noticed that the rise in the inhibitor concentration up to 1.0 M results in the reduction on corrosion rates being recorded, hence, the inhibition performance. However, 1.5 M and 2.0 M inhibitor concentration had higher corrosion rates compared to others. This study demonstrated that the inhibitor produces a film which adhere strongly to the MSS surface based on the Langmuir adsorption isotherm. Consequently, the combination of sodium benzoate with solanum tuberosum extract would be beneficial to significantly prolong MSS in industrial applications like oil drilling rigs, heat exchangers and marine installations.

Investigation of tool wear and energy consumption in machining Ti6Al4V alloy with uncoated tools

This research studies the energy consumption and wear mechanism of carbide cutting tools in dry machining of Ti6Al4V alloy. In the first phase of experiments, full factorial design experiments were employed to study the tool wear rate (R) and specific cutting energy (SCE) with respect to the machining conditions (cutting speed and feed rate). Results showed that machining responses such as tool wear and energy consumption are affected by cutting conditions, thus requiring investigation to understand the wear mechanisms. Therefore, in the second phase, additional experiments were performed to investigate the tool-workpiece interactions at the cutting conditions reported to have low, moderate, and high tool wear. It was revealed that strong adhesion and material transfer between the tool and workpiece caused high wear. Electron dispersive X-ray spectroscopy (EDX) analysis of worn tools showed that the transfer of tungsten (W) and cobalt (Co) to the workpiece and titanium to the tool surface is the primary cause of tool deterioration. As a result, diffusion and dissolution have degraded cutting performance and weakened the tool edge, leading to rapid wear. Furthermore, worn tools resulted in relatively higher energy consumption per unit volume of material removed at the tooltip. The degradation of cutting performance and weakening of the tool edge results in rapid wear and higher energy consumption. The study suggests that minimizing tool wear is crucial for energy reduction, improved sustainability, and cleaner production goals in dry machining of titanium-based alloys.

Failure analysis of FeCrAl heating coils exposed to a high-temperature, high-pressure ammonia environment

This work presents an investigation into the premature failure of FeCrAl heating coils after 48 h of continuous exposure to a high-pressure (12 bar) and high-temperature (700 °C) ammonia (NH3) environment while conducting a material nitridation test. Herein, we delve into the underlying causes and mechanisms associated with such a failure and the degradation of the coils. The study involves a detailed analysis of the formation of cracks and their initiation and propagation, with examination using optical microscopy, scanning electron microscopy (SEM), and electron dispersive spectroscopy (EDS). Examination of the topography of the fracture surface revealed the formation of brittle nitrides and cracks propagated through a quasi-cleavage fracture mechanism. Subsequent nitriding attack was attributed to the result of imperfections in the formed protective Al2O3 layer. This led to the primary conclusion that the premature failure of the heating elements was predominantly triggered by the nitriding process associated with the dissociation of NH3 and the diffusion of nascent nitrogen into the surface of the FeCrAl coils.

Nanoparticles in terrestrial sediments and the behavior of the spectral optics of Sentinel-3B OLCI Satellite images in a river basin of UNESCO World Cultural and Natural Heritage.

The dangerous chemical elements associated with nanoparticles (NPs) and ultra-fine sediment particles in hydrological bays have the capacity to move contaminants to large oceanic regions. The general objective of this study is to quantify the major chemical elements present in NPs and ultra-fine particles in aquatic sediments sampled from Guanabara Bay and compare these data to values determined through spectral optics using the Sentinel-3B Satellite OLCI (Ocean Land Color Instrument) during the winter and summer seasons of 2018, 2019, 2020, 2021, and 2022. This is done to highlight the impacts anthropogenic environmental hazards have on the marine ecosystem and human beings. Ten aquatic sediment field collection points were selected by triangulated irregular network (TIN). Samples were subjected to analysis by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersion spectroscopy (EDS), and transmission electron microscopy (TEM), which enabled a detailed analysis using scanning transmission electron microscopy (STEM). Geospatial analyses using Sentinel-3B OLCI Satellite images considered Water Full Resolution (WFR) at 300m resolution, in neural network (NN), normalized at 0.83µg/mg. A maximum average spectral error of 6.62% was utilized for the identification of the levels of Absorption Coefficient of Detritus and Gelbstoff (ADG443_NN) at 443m-1, Chlorophyll-a (CHL_NN) (m-3), and Total Suspended Matter (TSM_NN) (g m-3) at 581 sample points. The results showed high levels of ADG443_NN, with average values as high as of 4444m-1 (summer 2021). When related to the analyses of nanoparticulate sediments and ultrafine particles collected in the field, they showed the presence of major chemical elements such as Ge, As, Cr, and others, highly toxic to human health and the aquatic environment. The application of satellite and terrestrial surveys proved to be efficient, in addition to the possibility of this study being applied to other hydrological systems on a global scale.

Synthesis and Thermoluminescence Properties of Undoped Calcium Fluoride (CaF2) Nanoparticles using Co-Precipitation Method

This study investigated the thermoluminescence properties of undoped CaF2 nanoparticles synthesized via co-precipitation with ethanol. X-ray diffraction revealed pure CaF2 nanoparticles with a complete cubic structure and an average crystallite size of 36.5 nm. Scanning electron microscopy confirmed the nanoscale size, averaging 51.23 nm. Electron dispersive spectroscopy analysis showed that the sample mainly consists of Ca and F, with oxygen potentially introducing defects in the crystal structure. Synthesized nanoparticles TL glow curves exposed to 7 mGy of 90Sr beta rays exhibited a prominent peak at 205 oC in thermoluminescence glow curves, likely due to oxygen-induced defects that act as thermoluminescence activators. The thermoluminescence activating energy and the frequency factor of the CaF2 nanoparticles were determined using initial rise methods of approximately 0.83 eV and 5.99 x 10-19, respectively.

Excellent performance of amoxicillin and potassium iodide as hybrid corrosion inhibitor for mild steel in HCl environment: Adsorption characteristics and mechanism insight

Combining inhibitors is a key strategy to increase inhibitory efficacy because of synergistic effects. In this study, a green pharmaceutical inhibitor, amoxicillin (AML), was screened and compounded with potassium iodide (KI) to successfully obtain a synergistic and highly efficient green inhibitor. The results revealed that AML/KI have excellent anticorrosion ability for Q235 steel in 1 M HCl medium. At the optimal concentration ratio of 2 mM AML +5 mM KI, the inhibition efficiency was up to 97.7%, which was significantly higher than that of AML alone (57.4%). The hybrid inhibitor remarkably hinders the corrosion process by inhibiting both the cathodic and anodic reactions. Scanning electron microscopy, electron dispersive spectroscopy, contact angle measurement, ultraviolet–visible spectrometry and X-ray photoelectron spectroscopy, as well as Fourier transform infrared spectroscopy, results further confirm the outstanding inhibitory effect and the formation of synergistic adsorption films. Through density functional theory (DFT) calculations, we discovered that the KI salt significantly enhances the adsorption characteristics of AML/KI on the Fe surface, which is consistent with the experimental findings. This research paves the way for a new breed of green hybrid corrosion inhibitors to be created.

Asbestos Bodies in Human Lung: Localization of Iron and Carbon in the Coating

Asbestos is a term that includes six fibrous mineral phases related to different lung diseases, including asbestosis, lung cancer, and Malignant Pleural Mesothelioma (MPM). Since the last century, these minerals have been widely studied under their mineralogical/chemical and physical aspects with in vivo and in vitro studies to understand the mechanisms of their carcinogenicity. There are several techniques described in the literature, as optical and electron microscopies, for the identification of coated (asbestos bodies, ABs) and uncoated fibers, but only micro-Raman spectroscopy permits a sure characterization of these minerals—and of the related phases—directly in the histological sections of pulmonary parenchyma without any manipulation. In this case, the risk of the loss of associated inorganic phases from asbestos bodies (ABs) and fibers (e.g.: iron or carbonaceous micro-particles) is avoided. Asbestos bodies are produced by the activity of alveolar macrophages with degradation/inactivation of asbestos fibers. Inside the alveolar macrophages, organic and inorganic material settles on the foreign fibers forming an iron-rich proteic and carbonaceous coating. In this study, Variable Pressure Scanning Electron Microscopy with annexed Electron Dispersive Spectroscopy (VP-SEM/EDS) and micro-Raman spectroscopy were applied to the characterization of the phases in the ABs. Characterization of carbonaceous materials (CMs), observed in pristine asbestos phases in previous works, was therefore performed, addressing the micro-Raman laser beam on different points of the asbestos bodies, and Raman mappings on ABs were carried out for the first time. Coupling the data obtained by VP-SEM/EDS and micro-Raman spectroscopy, it was possible to collect information about the iron and carbonaceous phases adhered to the fibers, probably lost during the classical tissue digestion procedures. Information about both mineral and carbonaceous components might be useful to understand the whole structure of “asbestos bodies” and the inflammogenic and carcinogenic effects of the asbestos phases coupled to CMs, that might derive from cigarette smoke or from environmental pollution; this study might be useful to deepen also the possible detrimental role of ABs in the tissues.

K2CO3-Modified Smectites as Basic Catalysts for Glycerol Transcarbonation to Glycerol Carbonate.

A novel and cost-effective heterogeneous catalyst for glycerol carbonate production through transesterification was developed by impregnating smectite clay with K2CO3. Comprehensive structural and chemical analyses, including X-ray diffraction Analysis (XRD), Scanning Electron Microscopy (SEM)-Electron Dispersion Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) surface area analysis measurements, were employed to characterize the catalysts. Among the various catalysts prepared, the one impregnated with 40 wt% K2CO3 on smectite and calcined at 550 °C exhibited the highest catalytic activity, primarily due to its superior basicity. To enhance the efficiency of the transesterification process, several reaction parameters were optimized, including the molar ratio between propylene carbonate and glycerol reactor loading of the catalyst and reaction temperature. The highest glycerol carbonate conversion rate, approximately 77.13% ± 1.2%, was achieved using the best catalyst under the following optimal conditions: 2 wt% reactor loading, 110 °C reaction temperature, 2:1 propylene carbonate to glycerol molar ratio, and 6h reaction duration. Furthermore, both the raw clay and the best calcined K2CO3-impregnated catalysts demonstrated remarkable stability, maintaining their high activity for up to four consecutive reaction cycles. Finally, a kinetic analysis was performed using kinetic data from several runs employing raw clay and the most active K2CO3-modified clay at different temperatures, observing that a simple reversible second-order potential kinetic model of the quasi-homogeneous type fits perfectly to such data in diverse temperature ranges.