Dispersive Spectroscopy Research Articles

Study of cesium sorption by a Brazilian bentonite

Engineered and natural barriers compose the disposal system of near surface repository to store low and intermediate level radioactive wastes. Waterproofing barriers are constituted of clays, such as the bentonite, in order to avoid or to limit the release of radionuclides to with consequences to the environment and humans. Characteristics such as high cation exchange capacity, high adsorption capacity and high sealing capacity, are taken into consideration for choosing this material. The migration of radionuclides through protection barriers can occur in a variety of ways, such as surface water infiltration, groundwater intrusion, among others. Diffusion is the process which governs the contaminant transport through soil barriers. Adsorption is one of the processes that could be considered in the diffusion mechanism, and sorption isotherms are obtained from values measured in the batch-adsorption experiments. Therefore, such experiments were carried out in order to estimate the cesium sorption by the bentonite. The quantitative analysis was performed using atomic absorption and the energy dispersive X-ray fluorescence spectrometry. With the purpose to calculate the true value of cesium sorption, a mass-balance was made considering all the steps of the batch experiment, and it was found a 6% loss in the whole process. The quantity of cesium sorbed by the bentonite was 66.7 mg.g-1. At the moment, eight additional experiments are being performed, using solutions with different cesium concentrations, leading to all the necessary data for the isotherm.

Oxidation Behavior at 1173 K of Modified P/M Stainless Steel 316 L by Addition of Cr, Ni, and Cr with Ni

Abstract Specimens of P/M 316 L stainless steel and modified P/M 316 L stainless steel with various amounts of Cr, Ni, and Cr along with Ni additions were compressed by a 500 MPa-hydraulic press for a duration of 30 s and then sintered at 1573 K in a hydrogen atmosphere for 2.7 ks. The oxidation resistance tests of those specimens were carried out at 1173 K in air for 360 ks. The 5 wt.-% Cr-added specimen resulted in the best oxidation resistance with the lowest oxidation rate constant of 1.54 × 10-7 kg2 × m-4 × s-1. The oxidation products which formed inside the pores and on the surfaces of all specimens were analyzed using scanning electron microscope/energy dispersive spectroscopic (SEM/EDS) and X-ray diffraction (XRD) analysis techniques. The results show that the oxides forming on both inside pores and surfaces were identified as Cr2O3, Fe2O3, (Fe0.6Cr0.4)2O3, NiFe2O4 and NiCr2O4 in all tested conditions. The measured hardness of the modified specimens was in the range of 87-92 HRB, compared to the hardness of the 316 L specimen, which was 93 HRB. Increasing the amount of powder added provided a slightly lower hardness value due to increased porosity.

Metallo-stannosilicates as inorganic supports to immobilization of lipase from Thermomyces lanuginosus for biodiesel production

This study reports the application of metallo-stannosilicates as potential inorganic solid matrixes for enzymes immobilization and their use as a heterogenous catalysts in enzymatic transesterification reactions for the conversion of triacylglycerides into fatty acid ethyl esters (FAEEs). Several stannosilicates were synthesized and physicochemical characterized by X-ray powder diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS), Brunauer-Emmett-Teller (BET)-N2 surface area analysis and solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR 29Si and 119Sn nuclei) techniques. The experimental results for enzymes immobilization were promising, especially for a nickel ion-exchanged metallo-stannosilicate, which were able to immobilize 82 +- 6% of Thermomyces lanuginosus lipase and also kept a high enzymatic activity (42 +- 3 U mg�1). Systematic catalytic reactions for conversion of refined palm oil (Elaeis guineensis) using some of these stannosilicates enzymes complexes yielded 63.3 +- 0.7% of FAEEs. It is worth noticing that, when the transesterification reaction was performed with (a) the as-made stannosilicate without enzymes and (b) the equivalent amount of immobilized Thermomyces lanuginosus lipase in its free form, the FAEEs yield sharply decreased to less than 5.0% and 6.3 +- 0.3%, respectively. This result is a clear evidence of a synergistic effect among the metallo-stannosilicates and the immobilized enzymes.

Rapid elemental composition analysis of spinach samples employing wavelength dispersive X-ray fluorescence spectroscopy

The increasing demand to carry out nondestructive analysis with minimal sample preparation for the detection of chlorine element in the spinach samples requires advanced analytical techniques with better energy resolution. The emergence of wavelength dispersive X-ray fluorescence instruments offers new chances for fast and inexpensive plant leaf analysis, both as laboratory and in-situ-based systems. Earlier efforts to use X-ray fluorescence analyses for various plant samples, especially spinach leaves, were limited by the large background caused by scattering of the primary X-ray source which has been overcome by using the commercial wavelength dispersive technique. It is a potential influential research tool for the study of trace elemental composition analysis under different analytical parameters and simple sample preparation protocols. In the present work, the chlorine content ∼0.8% has been measured in the spinach leaf standard reference material (SRM 1570a) from the National Institute of Standards and Technology, USA by using the wavelength dispersive X-ray fluorescence technique employing a fundamental parameter approach. Keeping in view the importance of the knowledge about the chlorine content in plant leaf samples and the reliability of the methodology used in the present work to determine chlorine content, it is recommended that the present measured chlorin.e concentration be included in the datasheet of certified values by the National Institute of Standards and Technology, the USA for effective use of this standard reference material.

Organobentonites Modified with Poly(Acrylic Acid) and Its Sodium Salt for Foundry Applications.

The article aims to verify the possibility of obtaining an organic–inorganic material acting as both a binder and a lustrous carbon carrier in bentonite-bonded molding sands. Due to the wide industrial application, organoclays can be considered as innovative materials supporting the foundry technology in meeting environmental requirements. In this study, the organic modification of montmorillonite in calcium bentonite (SN) was performed by poly(acrylic acid) (PAA) and its sodium salt (PAA/Na). Additionally, for the purpose of comparison, the sodium-activated bentonite/poly(acrylic acid) (SN-Na/PAA) composites were also prepared. The collective analysis of the research results used in the assessment of the mineral/polymer interaction mechanism indicates surface adsorption combined with the intercalation of PAA monolayer into the mineral interlayer spaces. Materials were characterized by the combination of Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) methods. Based on the XRD analysis, the influence of PAA/Na on the aluminosilicate layered structure was found to be destructive, which may adversely affect the binding properties of SN/PAA/Na composites considered as a potential group of new foundry binders. The SN/PAA and SN-Na/PPA composites (with appropriate polymer content) can act as a binding agent in the synthetic molding sand technology, despite coating the bentonite particles with polymer molecules. The risk of losing the mineral′s binding capacity is reduced by the good binding properties of pol(acrylic acid) itself. The article is the first stage (preceding the thermal analysis and the strength tests of molding sands with the prepared organobentonites) in determining the possibility of obtaining a new full-value foundry binder in molding sands with bentonite.

Improved Hydrogenation Kinetics of TiMn1.52 Alloy Coated with Palladium through Electroless Deposition.

The deterioration of hydrogen charging performances resulting from the surface chemical action of electrophilic gases such as CO2 is one of the prevailing drawbacks of TiMn1.52 materials. In this study, we report the effect of autocatalytic Pd deposition on the morphology, structure, and hydrogenation kinetics of TiMn1.52 alloy. Both the uncoated and Pd-coated materials were characterized using scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD). XRD analyses indicated that TiMn1.52 alloy contains C14-type Laves phase without any second phase, while the SEM images, together with a particle size distribution histogram, showed a smooth non-porous surface with irregular-shaped particles ranging in size from 1 to 8 µm. The XRD pattern of Pd-coated alloy revealed that C14-type Laves phase was still maintained upon Pd deposition. This was further supported by calculated crystallite size of 29 nm for both materials. Furthermore, a Sieverts-type apparatus was used to study the kinetics of the alloys after pre-exposure to air and upon vacuum heating at 300 °C. The Pd-coated AB2 alloy exhibited good coating quality as confirmed by EDS with enhanced hydrogen absorption kinetics, even without activation. This is attributed to improved surface tolerance and a hydrogen spillover mechanism, facilitated by Pd nanoparticles. Vacuum heating at 300 °C resulted in removal of surface barriers and showed improved hydrogen absorption performances for both coated and uncoated alloys.

Sulfobutylether-beta-cyclodextrin-enabled antiviral remdesivir: Characterization of electrospun- and lyophilized formulations

Veklury™ by Gilead Sciences, Inc., containing antiviral drug, remdesivir (REM) has received emergency authorization in the USA and in Europe for COVID-19 therapy. Here, for the first time, we describe details of the non-covalent, host-guest type interaction between REM and the solubilizing excipient, sulfobutylether-beta-cyclodextrin (SBECD) that results in significant solubility enhancement. Complete amorphousness of the cyclodextrin-enabled REM formulation was demonstrated by X-ray diffraction, thermal analysis, Raman chemical mapping and electron microscopy/energy dispersive spectroscopy. The use of solubilizing carbohydrate resulted in a 300-fold improvement of the aqueous solubility of REM, and enhanced dissolution rate of the drug enabling the preparation of stable infusion solutions for therapy. 2D ROESY NMR spectroscopy provided information on the nature of REM–excipient interaction and indicated the presence of inclusion phenomenon and the electrostatic attraction between anionic SBECD and nitrogen-containing REM in aqueous solution.

Impact of toxic metal pollution on surface water pollution: a case study of Tohma stream in Sivas, Turkey

ABSTRACT This study was executed to investigate the acidification and heavy metal (Cr, Mn, Fe, Ni, Cu, Zn, and Pb) pollution of Tohma stream flowing near Kangal lignite-fired thermal power plant located in Kangal district of Sivas province in the Central Anatolia region of Turkey. All water samples were screened for pH to evaluate the acidification of the Tohma stream. Water samples were found in moderately alkaline according to pH values (8.1–8.7). The average concentrations of Cr, Mn, Fe, Ni, Cu, Zn and Pb in water samples from the Tohma stream were determined as 0.94, 2.27, 13.78, 1.24, 1.98, 0.32 and 0.54 mg L−1 using energy dispersive X-ray fluorescence spectroscopy, respectively. Metal pollution index (MPI) and metal evaluation index (MEI) were estimated to evaluate the pollution of Tohma water samples with heavy metals. The values of MPI and MEI varied from 312 (medium pollution) to 9715 (high pollution) with an average of 4713 (high pollution) and 181(medium pollution) to 317 (high pollution) with an average of 226 (medium pollution), respectively. The results of MPI and MEI revealed that investigated water samples are seriously polluted with toxic heavy metals and inadequate for drinking and irrigation water utilisation.

Elemental composition of Eucheuma cottonii and Gracillaria sp. using scanning electron microscope-energy dispersive spectroscopic analysis

Indonesia is a major producer of the E. cottonii seaweed and Gracillaria sp. in the world. The farmers usually dry that seaweeds before sending them to plant factories to be processed into carrageenan or agar. In the present work, E. cottonii and Gracillaria sp. seaweed’s chemical composition were observed using Scanning Electron Microscope-Energy Dispersive Spectroscopic (SEM-EDS) analysis, and the distribution of the main salt-minerals in the surface and the cross-section thallus of both samples were conducted. The results showed that the surface of E. cottonii contains the following order of elements Cl> K> Na> S> Ca> C> O> Si> Al> Mg> Fe> Mn> Zn and in the cross-section contains order of elements S> Cl> K> C > O> Na> Mg> Ca> Al> Zn> Fe> Si> Mn. Whereas on the surface of the Gracillaria sp. showed the presence of elements in the following order Cl> K> Si> C> O> Al> S> Fe> C> Mg> Na> Mn> Zn and on the cross-section found elements in the following order Cl> K> C> O> S> Na> Si> Al> Mg> Fe> Ca> Zn> Mn. The EDS mapping on both seaweeds surface and cross-section showed a random distribution of salt-forming elements Na, K and Mg. Furthermore, the presence of a higher amount of K, Na, adequate amount Mg, and other essential elements indicated both seaweeds’ potential to be developed for salts with special functional properties.

Dispersive solid phase extraction of Ni2+ using graphene oxide-polyethylenimine nanocomposite as an efficient adsorbent in different real samples; Response surface methodology based on central composite design optimisation

ABSTRACT An efficient modified graphene oxide adsorbent was used for dispersive solid phase extraction of trace levels of Ni2+ followed by its determination using electrothermal atomic absorption spectrometry (ETAAS). Graphene oxide modified polyethylenimine nanocomposite (GO-PEI) was used as an adsorbent and characterised by the Fourier Transform-Infrared Spectrophotometry (FT-IR), Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-Ray Spectroscopy (EDX) and X-Ray Diffraction Analysis (XRD). In order to optimise the critical parameter affecting the extraction efficiency of Ni2+, the response surface methodology based on central composite design (RSM-CCD) was used. Under the optimum condition, the calibration curve was found to be linear in the range of 0.1–2.0 µg L−1 with a correlation coefficient of 0.9997. The inter-day relative standard deviation (RSD) was 3.5% based on seven replicate analysis of 1.0 µg L−1 Ni2+ and the limit of detection (LOD) was 0.018 µg L−1 (n = 8). The accuracy of the proposed method was checked by the analysis of certified reference material-trace metals in drinking water (CRM-TMDW) and then it was successfully applied for determination of trace levels of Ni2+ in different real samples.

Investigation into the Structural, Chemical and High Mechanical Reforms in B4C with Graphene Composite Material Substitution for Potential Shielding Frame Applications.

In this work, boron carbide and graphene nanoparticle composite material (B4C–G) was investigated using an experimental approach. The composite material prepared with the two-step stir casting method showed significant hardness and high melting point attributes. Scanning electron microscopy (SEM), along with energy dispersive X-ray spectroscopy (EDS) analysis, indicated 83.65%, 17.32%, and 97.00% of boron carbide + 0% graphene nanoparticles chemical compositions for the C-atom, Al-atom, and B4C in the compound studied, respectively. The physical properties of all samples’ B4C–G like density and melting point were 2.4 g/cm3 density and 2450 °C, respectively, while the grain size of B4C–G was in the range of 0.8 ± 0.2 µm. XRD, FTIR, and Raman spectroscopic analysis was also performed to investigate the chemical compositions of the B4C–G composite. The molding press composite machine was a fabrication procedure that resulted in the formation of outstanding materials by utilizing the sintering process, including heating and pressing the materials. For mechanical properties, high fracture toughness and tensile strength of B4C–G composites were analyzed according to ASTM standard designs. The detailed analysis has shown that with 6% graphene content in B4C, the composite material portrays a high strength of 134 MPa and outstanding hardness properties. Based on these findings, it is suggested that the composite materials studied exhibit novel features suitable for use in the application of shielding frames.

Porous Nickel Based Half-Cell Solid Oxide Fuel Cell and Thin-Film Yttria-Stabilized Zirconia Electrolyte

In this work, a porous nickel anode for thin-film solid oxide fuel cell prepared by the simple powder hot-pressing method is investigated. Powders of Ni and pore-forming agent (PFA) were thoroughly mixed in different ratios, pressed in a mold and further sintered. The polishing technique with Yttria-Stabilized Zirconia (YSZ) powder has been developed to decrease the surface roughness of Ni-based anode in order to deposit a crack-free electrolyte layer. The 3 μm YSZ thin-film electrolyte was deposited by the pulsed laser deposition technique on the surface of the anode. Morphological and elemental analyses of the samples were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses. X-ray diffraction was used for phase analysis and structural characterization. The specific surface areas of the resulting anodes were calculated from their isotherms of N2 adsorption and desorption using the Sorbtometer and calculated by Brunauer Emmett-Teller (BET) method. As a result, the highest mechanical strength and specific surface area (15.42 m2g-1) possessed a sample with the content of PFA equal to 40%, while its ionic conductivity at 800 °C reached 6. 4∙10-2 S/cm.

Metamorphic graphite from Szendr\u0151l\xe1d (Szendr\u0151 Mts., NE-Hungary) detected by simultaneous DTA-TG

Graphite, one of the polymorphic forms of carbon, has become a versatile industrial material of nowadays due to its particular attributes. It is used mainly in the automobile industry, metal extractive industry and in the high-tech industry. Moreover, it is also included in the list of critical raw materials for the EU. Our aim was to prove the presence of graphite by thermal analysis beyond X-ray powder diffraction (XRD) and Raman spectroscopy. Thermogravimetry yields comparable results with quantitative XRD. The formation conditions are described by Raman spectrometry and microscopy examinations of drill core samples from Szendrőlád (Szendrő Mts, NE-Hungary; (Szendrőlád Limestone Formation, middle-late Devonian, shelf-basin facies). Polished rock slabs were made for optical microscopy, scanning electron microscopy with energy dispersive spectrometry (SEM–EDS) and Raman spectroscopy. X-ray powder diffraction (XRD) and thermal analysis (DTA-TG) measurements were made on powders. Based on our results, the graphite is epigenetic; its quantity varies between 1.5–3 mass% in the samples. It was developed in 20–50 μm sized flakes, which are often arranged in > 300 μm sized aggregates. Graphite was formed during regional metamorphism from the organic matter-rich shales. The average formation temperature, calculated from the results of Raman spectroscopy, is around 410 °C (± 30 °C). The Raman measurements also indicated the presence of a partially graphitized (disordered graphite) material beside graphite.

Solid-state synthesis and photodegradation property of anatase TiO2 micro-nanopowder by sodium replacement

To investigate the effect of the doping of alkali metal on the band structure and photocatalytic property of titanium oxide crystals, the mesoporous sodium doped titanium dioxide (Na–TiO2) micro-nano powder was synthesized by the solid-state reaction (SSR) method, and characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectrum (UV–Vis), scanning electron microscopy/energy dispersive spectroscopy, X-ray photoelectron spectroscopy (XPS), N2 desorption-adsorption. Meanwhile, the UV-degradation properties of Na–TiO2 and P25–TiO2 powder materials for hydroquinone (HQ) were studied. The results show that sodium ions with the low charge density entered into the (004) crystal place of anatase TiO2, producing the dislocation defects of TiO2 crystal structure. The spherical-like morphology micro-nanopowder with a size of 50–500 nm, sodium content of 3.36(wt%), the bandgap width of 3.08 eV, BET surface area of 111.52 m2/g, the pore size distribution center of 4.72 nm, the pore volume of 0.32 cm3/g are obtained, respectively. Within 60min and 25 °C, the UV-degradation rate (97.32%) of mesoporous Na–TiO2 powders for hydroquinone is 2.62 times for that (37.08%) of P25–TiO2 powder. It is mainly derived from the increase of dislocation density of Na–TiO2 powder, and the results of the synergistic photocatalystic degradation of hydroxyl radicals and superoxide radicals. And the photocatalytic efficiency is associated with pH value, photocatalyst dosage, concentration of HQ, irradiation time and stability.

Novel Alhagi maurorum leaves mediated synthesis of titanium nanoparticles for human breast carcinoma applications: a preclinical trial study

IntroductionIn this study, titanium nanoparticles (TiNPs) were synthesized in an aqueous medium using Alhagi maurorum extract as a stabilizing and reducing agent.Material and methodsUltraviolet–visible spectrophotometry (UV-Vis), Fou�rier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDS) were the techniques to characterize the biosynthesis of TiNPs. To survey the anti-human breast cancer effects of TiNPs, MTT assay was used on the common breast cancer cell lines, i.e., breast cancer (breast adenocarcinoma (MCF7), infiltrating ductal cell carcinoma (Hs 319.T), inflammatory carcino�ma of the breast (UACC-732), and metastatic carcinoma (MDA-MB-453)) cell lines. TiNPs’ crystal size was measured as 16.08 nm. SEM images exhibited a uniform spherical morphology in size range of 12.16 to 43.46 nm for the biosynthesized nanoparticles respectively.ResultsThe cell viability of breast carcinoma cells decreased dose-de�pendently in the titanium nanoparticles’ presence. The IC50 values of A. mau�rorum and titanium particles on the MCF7 cell line were 680 and 359 µg/ml, on the Hs 319.T cell line were 507 and 191 µg/ml, on the UACC-732 cell line were 477 and 217 µg/ml, and on the MDA-MB-453 cell line were 507 and 191 µg/ml, respectively. TiNPs had high anti-breast cancer activities dose-dependently against MCF7, Hs 319.T, UACC-732, and MDA-MB-453 cell lines.ConclusionsThe best result of anti-breast cancer effects was seen in the case of the Hs 319.T cell line.

Selective passivation behavior of galena surface by sulfuric acid and a novel flotation separation method for copper-lead sulfide ore without collector and inhibitor

Here, we present a novel efficient passivation-separation method for galena and chalcopyrite that includes a novel sulfuric acid selective passivation process for galena and a special flotation process in which conventional inhibitors and collectors are not added. The surface passivation mechanism of galena was characterized by surface contact angle measurements, scanning electron and dispersive spectrometry (SEM-EDS) analysis and X-ray photoelectron spectroscopy (XPS) analysis. The contact angle measurements indicated that sulfuric acid passivation increased the surface hydrophobicity difference between galena and chalcopyrite, which led to the large difference in their floatabilities. The results of the passivation-flotation experiments for the galena-chalcopyrite mixture confirmed that the selective inhibition of galena was realized with this new process, and the floatability of galena was drastically reduced while that of chalcopyrite was slightly promoted; thus, the efficient separation of galena and chalcopyrite was achieved only with the addition of frothers. The SEM-EDS and XPS results revealed that the S element on the galena surface was gradually oxidized from S2− to SO42− during the passivation process, which generated a layer of hydrophilic lead sulfate (PbSO4), while a layer of floatable copper sulfides was formed on the surface of chalcopyrite. In this study, a new highly efficient copper-lead sulfide ore separation method was developed, and the interrelatedmechanism was studied in detail.

Real-Time Detection of Packaged Seer Fish Spoilage Using Halochromic Optical Nose

ABSTRACT Development of a biodegradable and recyclable halochromic biosensor for monitoring spoilage of packaged seer fish is described in this study. The biosensor was prepared completely from materials of natural origin. The sensor was characterized by X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) and image processing by CIELab. The biosensor indicated spoilage of fish by exhibiting a visible color change from brownish pink to yellowish green. The results of the biodegradability test indicated that the developed sensors decompose at the rate of 60–70% in 2 weeks. This biosensor can be recycled at least six times. It was also estimated that the cost for one biosensor per package was approximately 2 cents. Thus, the biosensor developed in this study is economical, biodegradable, and efficient in monitoring spoilage of packaged fishes. Hence, this economical biosensor can easily be adopted by retail sellers and exporters. The biosensor developed in this study is promising for monitoring spoilage of packaged fishes in retail markets.

Influence of the Catalyst Layer Structure Formed by Inkjet Coating Printer on PEFC Performance.

In this study, we investigated the influence of the Catalyst-Layer (CL) structure on Polymer Electrolyte Fuel Cell (PEFC) performance using an inkjet coating printer, and we especially focused on the CL thickness and the electrode area. In order to evaluate the influence of CL thickness, we prepared four Membrane Electrode Assemblies (MEAs), which have one, four, five and six CLs, respectively, and evaluated it by an overpotential analysis. As a result, the overpotentials of an activation and a diffusion increased with the increase of thickness of CL. From Energy Dispersive X-ray spectroscopy (EDX) analysis, because platinum twines most ionomers and precipitates, the CL separates into a layer of platinum with a big grain aggregate ionomer and the mixing layer of platinum and ionomer during the catalyst ink drying process. Consequently, the activation overpotential increased because the three-phase interface was not able to be formed sufficiently. The gas diffusivity of the multilayer catalyst electrode was worse than that of a single layer MEA. The influence of the electrode area was examined by two MEAs with 1 and 9 cm2 of electrode area. As a result, the diffusion overpotential of 9 cm2 MEA was worse than 1 cm2 MEA. The generated condensate was multiplied and moved to the downstream side, and thereafter it caused the flooding/plugging phenomena.

Complex reaction behaviour of ceramic mould with the molten AZ91 alloy during investment casting

The effects of different pouring temperatures on the reaction behaviour of the ceramic shell with the molten Mg-9%Al-1%Zn-0.4%Mn (all are in wt-%) (AZ91) alloy during investment casting were studied. The scanning electron microscopy (SEM) micrographs with energy dispersive spectroscopy (EDS) analysis illustrated a complex interaction behaviour of the alloy with the mould components at various pouring temperatures. The MgO + MgAl2O4 compounds were formed on the surface of investment cast alloy at the pouring temperature of 600°C. With increasing the temperature to 650°C, the MgO compounds with the Al2O3 particles were observed at the interface of metal/mould. The Al2O3 particles were the main compound on the surface of alloy at the pouring temperature of 700°C. The formation of Al2O3 particles instead of the MgO compounds on the surface was related to the increase of magnesium evaporation by enhancement of the pouring temperature and also diffusion of Al2O3 particles from the ceramic shell to the surface of the alloy.

Chemical Evaluation of Energy Dispersive X-ray Spectroscopy Analysis of Different Failing Dental Implant Surfaces: A Comparative Clinical Trial.

The aim of the present study is to compare two different implant surface chemistries of failing dental implants. Sixteen patients (mean age: 52 ± 8.27 with eight females and eight males) and 34 implants were included in the study. Group-I implants consisted of a blasted/etched surface with a final process surface, while Group-II implants consisted of the sandblasted acid etching (SLA) method. The chemical surface analysis was performed by the energy dispersive X-ray spectroscopy (EDX) method from coronal, middle, and apical parts of each implant. Titanium (Ti) element values were found to be 20.22 ± 15.7 at.% in Group I and 33.96 ± 13.62 at.% in Group-II in the middle of the dental implants. Aluminum (Al) element values were found to be 0.01 ± 0.002 in Group-I and 0.17 ± 0.28 at.% in Group II in the middle of the dental implants, and statistically significant differences were found between the groups for the Al and Ti elements in the middle of the dental implants (p < 0.05). There was a statistically significant difference for the Ti, Al, O, Ca, Fe, P, and Mg elements in the coronal, middle, and apical parts of the implants in the intragroup evaluation (p < 0.05). It is reported that different parts of the implants affected by peri-implant inflammation show different surface chemistries, from coronal to apical, but there is no difference in the implants with different surfaces.