Scanning Electron Microscopy Energy-dispersive X-ray Analysis Research Articles

Green Synthesis, Characterization, and Photocatalytic Activity of Zinc Oxide Nanoparticles on Photodegradation of Naphthol Blue Black Dye

Zinc oxide (ZnO) nanoparticles have been successfully synthesized using water extract of red dragon fruit (Hylocereus polyrhizus) stem with zinc acetate dihydrate as a precursor of ZnO. Chemical compounds contained in the red dragon fruit stem extract, such as phenolics, terpenoids, and steroids, acted as reducing agents, stabilizers, and capping agents. The phase structure, crystallite size, functional groups, shape, and morphology of ZnO nanoparticles were determined by X-ray diffraction (XRD), Fourier Transform infrared (FT-IR) Spectroscopy, and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX). The XRD pattern confirmed the crystallinity of synthesized zinc oxide was in the zincite (ZnO) phase with an average crystallite size of 79.09 nm. Spectroscopy FTIR analysis showed that the synthesized ZnO nanoparticles had characteristics similar to the ZnO standard/commercial. SEM-EDX analysis revealed that the synthesized ZnO nanoparticles were spherical, evenly distributed, and homogeneous particle size. The photocatalytic activity of synthesized ZnO nanoparticles was evaluated on the photodegradation of naphthol blue black (NBB) dye. The results showed that the synthesized ZnO nanoparticles have high photocatalytic activity that can degrade NBB dye up to 98.82%. This high photocatalytic activity was obtained at operating parameter conditions with the initial pH of NBB at 2, the dosage of ZnO nanoparticles at 250 mg, and the initial dye concentration at 10 ppm.

Sustainable fabrication of biogenic Fe–Zn nano core-shell and their photocatalytic efficiency against third generation antibiotics

The photocatalysis of third generation antibiotics was deliberated using biogenic iron oxide (FeO NPs) and iron-zinc (Fe–Zn) nano core-shell. Photocatalysts were prepared from aqueous extract of Adiantum incisum (Ai) by reacting with apposite salt solutions. FeO NPs were synthesized by mixing 5 % Ai extract with 5 mM FeSO4.7H2O at alkaline pH (50 °C). While Fe–Zn nano core-shell were synthesized by coating ZnO NPs on FeO NPs using successive reduction method. Synthesis and stabilization of nanoparticles were substantiated by diverse surface plasmonic resonance peak of FeO NPs and Fe–Zn nano core-shell at explicit wavelength ranges. Band gap energy values, Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), Raman and Scanning Electron Microscope (SEM) analysis validates that coating was done efficaciously. Fourier Transform Infrared Spectroscopy (FTIR) recognized the role of plant phytochemicals in NPs reduction and stabilization. SEM-Energy Dispersive X-Ray analysis (EDX) analysis unveiled that FeO NPs and core-shell aggregates are orbicular in shape. Average crystalline size of FeO NPs and Fe–Zn nano core-shell obtained from XRD was 15.64 nm and 22.94 nm respectively. The photocatalytic degradation of Ampicillin, Levofloxacin and Ceftriaxone under UV and Sunlight displayed that Fe–Zn nano core-shell have high degradation capability than FeO NPs. Degradation potential was higher in UV than in sunlight. Maximum degradation of Ampicillin (74.4 %) was attained under UV light and (60.31 %) in sunlight followed by Levofloxacin. Degradation was further confirmed by conducting FTIR analysis and antimicrobial studies. Gas Chromatography-Mass Spectrometry detected Hexadecenoic acid as the main degradation product in nano treated Ampicillin and Levofloxacin.

Efficacy of Chitosan Scaffolded Calcium Silicate-based Cements for Treating Internal Resorption Defects with Perforation: In Vitro Study.

The present study aimed to evaluate the efficacy of chitosan scaffold combined with calcium silicate cements in the management of internal resorption with perforation. Internal resorption cavities were simulated in 20 human permanent maxillary incisors that were then divided into two groups: group I - biodentine and group II - chitosan scaffold combined with biodentine. The samples were evaluated for the mineralization activity at the end of the 7th day and 14th day using scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis. The data were recorded, tabulated, and then statistically analyzed. From the SEM-EDX analysis, the mean score of calcium and phosphorus ion uptake by the material was obtained. Statistical analysis by nonparametric Mann-Whitney test showed that there was statistically significant difference in calcium ion uptake at the end of the 7th day (p = 0.016) and at the end of 14th day (p = 0.043) between the group biodentine and group chitosan scaffold combined with biodentine (p < 0.05). In this present study, the use of chitosan scaffolds combined with biodentine showed a statistically significant difference in the mineralization activity when compared with pure biodentine. These scaffolded biomaterials exhibited greater potential for mineralization in vitro which can be efficiently used for the management of teeth with internal resorption with perforation. Further clinical trials are required for the understanding of their behavior in real-world scenarios. Calcium silicate cements have often exhibited defective hard tissue barrier formation and hence there is a pressing need to search for newer biomaterials that can overcome these shortcomings. Scaffolded biomaterials provide a controlled microcellular environment for bioactivity, and they were found to be efficient in the remineralization of tooth structure. The present study findings indicate that these chitosan scaffolds can be efficiently used in combination with calcium silicate cements for the management of internal resorption with perforation to enhance the treatment outcome.

Remineralization Potential of a Novel Biomimetic Material (Self-assembling Peptide P11-4) on Early Enamel Caries: An In Vitro Study.

To assess the remineralizing potential of self-assembling peptide P11-4 and compare it to the remineralizing potential of fluoride varnish using DIAGNOdentTM, as well as the amount of mineral gain after application of fluoride varnish and self-assembling peptide P11-4. This study included 20 premolars extracted during orthodontic therapy with all surfaces intact and free of hypoplastic regions, white spot lesions (WSL) and dental caries. The teeth sample for Curodont RepairTM (self-assembling P11-4) and Bifluorid 10® (fluoride varnish) was equally divided. On each tooth surface, a 2 × 2 mm window was created. The samples were immersed in a demineralizing solution for 96 hours before being subjected to DIAGNOdentTM pen reading, ICDAS-II scoring, and scanning electron microscopy-energy-dispersive X-ray (SEM-EDX) analysis on one half of the sample. The remineralizing agents were applied to the second half of the sample according to the manufacturer's instructions and placed in artificial saliva for 21 days, with the artificial salvia being replaced every 24 hours. After 21 days, the second half of the sample was subjected to DIAGNOdentTM pen reading, ICDAS-II score, and SEM-EDX analysis. Following remineralization, the DIAGNOdentTM pen and ICDAS-II score values differed statistically between the two groups, with the Bifluorid 10® group reporting higher mean values (p > 0.05) using t-test analysis. Energy-dispersive X-ray analysis using the t-test revealed a statistically significant result for remineralization (p < 0.05), with CurodontTM Repair group (55.150.84) reporting better mean values than Bifluorid 10® for phosphorus and calcium, but Bifluorid 10® reporting a higher result in remineralization (p < 0.05) than CurodontTM Repair for fluoride. CurodontTM Repair showed better remineralizing potential compared with Bifluorid 10® varnish. In terms of the mineral gain, CurodontTM Repair showed better results for calcium and phosphorus post-remineralization. Whereas Bifluorid 10® showed a higher gain in terms of fluoride. Self-assembling peptide P11-4 can be used as an alternative to fluoride varnish for remineralizing WSL. Self-assembling polypeptide P11-4 is a novel remineralizing agent for initial enamel lesions, which is the least-invasive method of enamel remineralization.

Pillarization of Sumatera Bentonite by Sodium-assisted As Effective Adsorbent of Anionic Surfactants Sodium Lauryl Sulphate (SLS) Waste

In this work, the Sumatera bentonite was sodium-pillarized in a new low-temperature and restricted time preparation route and then applied in anionic surfactant sodium lauryl sulphate removal. Structure characterization used Fourier Transform Infra Red (FT-IR), Scanning Electron Microscope - Energy Dispersive X-ray (SEM-EDX), X-ray Diffraction (XRD), and Brunauer–Emmett–Teller (BET) analysis. A strong peak at 22° and 35.66° in XRD analysis was detected as Sodium-pillar that increased crystallinity, then the functional changes of dehydration in lattice structure were detected in 1013 cm−1 by FTIR analysis. The morphology and compositional transformation were analyzed by SEM-EDX and BET analysis, denoted by increasing particle shape and sodium intercalant composition homogeneity. Moreover, the surface area increased from 61.791 to 66.086 m2/g. The sodium lauryl sulphate adsorption by bentonite-Na reached maximum capacity at 8.403 mg/g, which is higher than the pristine bentonite (5.747 mg/g) under the optimum condition. The adsorption mechanism is feasible, endothermic, and conformed to the pseudo-second-order and Freundlich adsorption model. The new route proposed for sodium intercalation effectively improves the Sumatera bentonite adsorption ability to remove sodium lauryl sulphate waste. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Failure Analysis of Once-Through Steam Generator (OTSG) Tube

Abstract The once-through steam generator (OTSG) produces superheated steam using purified feed water. The plant-specific water quality, steam quality, high temperature, and pressure operations lead to the leakage of the OTSG tubes with economic, safety, and environmental consequences. Tube leakage is one of the most frequent causes of OTSG tube failure. A leaking tube was discovered within the OTSG unit of the 110 MW cogeneration plant. The failed section of the tube was removed from the steam generator. Several metallurgical examinations of this tube segment were performed to identify the failure mode and cause. A portion of the tube was analyzed using optical emission spectroscopy (OES) to determine the alloy composition. The results confirmed that the tubing was fabricated from a material consistent with chemical specifications for ASME Specification SB 407 Inconel Alloy 800 (UNS N08800). Glass bead blasting was used to determine the deposit-weight-density (DWD). The DWD value was a maximum of 5.1 g/ft2. The maximum internal deposit thickness was 0.002 in. No evidence of overheating was observed. Scanning electron microscope-energy-dispersive x-ray analysis (SEM-EDXA) was used to determine the elemental composition of the internal deposits. The results indicated that the internal gray deposits primarily comprised iron, chromium, and nickel compounds. There were also fewer amounts of sodium, silicon, aluminum, potassium, and calcium species. The subject tube failure involved a through-wall crack that occurred as stress corrosion cracking (SCC). Additions of caustic solution used in OTSG water treatment practices potentially induced corrosive substances into the tube.

Laser Application in Remineralisation of Enamel after Interproximal Reduction: An In-vitro Scanning Electron Microscopic Study

Introduction: Interproximal Reduction (IPR) or reproximation of enamel is of prime importance in orthodontics for correcting arch length-tooth size discrepancies. Despite its widespread application, IPR has been associated with adverse effects on the enamel surface. Aim: The aim of this study was to investigate whether laser application, when combined with fluoride application, enhances the remineralisation potential of enamel. Materials and Methods: This in-vitro study was conducted at Saveetha Institute of Medical and Technical Sciences (SIMATS), Chennai, Tamil Nadu, India, from December 2021 to July 2022. It involved 54 extracted teeth, divided into three groups of 18 samples each. Reproximation of 0.25 mm was performed on the proximal enamel surface of each tooth. Group 1 served as the control, group 2 was subjected to Fluor Protector, and group 3 received low-level laser therapy (Er,Cr:YSGG) after Fluor Protector application. Fluor Protector (Ivoclar Vivadent) was applied for seven days. Following the seven-day fluoride administration, a laser treatment using 0.75 W of power and 8.5 J/cm2 of energy was applied for 20 seconds. Microhardness testing was conducted on the samples using a Vickers Hardness Tester. All specimens underwent surface topographic analysis with Scanning Electron Microscopy (SEM) and were evaluated for mineral content (% weight) using SEM-Energy Dispersive X-Ray analysis (EDX). Paired t-tests were performed to compare the pre- and post-microhardness values, while one-way Analysis Of Variance (ANOVA) test and Tukey’s Post-hoc test were used to compare the microhardness values between the groups. Results: The mean microhardness values recorded for group 1, group 2, and group 3 were 209.4±18.4 N/mm2 , 215.16±21.0 N/ mm2 , and 233±18.05 N/mm2 , respectively. ANOVA test revealed a significant difference in microhardness values between group 1 and group 2 (p-value=0.004), as well as between group 1 and group 3 (p-value=0.001). The microhardness value was highest for group 3, followed by group 2 post-intervention. SEM analysis showed that laser-treated enamel surfaces were smoother, with well-coalesced enamel rods. The porous structure of enamel was lost due to fluoride deposition in group 2 and group 3, resulting in a smooth surface. Conclusion: The combined application of fluoride and laser therapy demonstrated synergistic effects in remineralising the slenderised enamel. This simple, non-invasive technique may benefit patients undergoing IPR procedures by reducing the occurrence of dental caries.

ZnO-Enhanced Reduced Graphene Oxide Electrodes from Cocoa Shell: Nanoarchitectonics Platform for Photoelectrocatalytic Detection of Methylene Blue.

In this study, we report the successful preparation of reduced graphene oxide modified zinc oxide (rGO-ZnO) composites from cocoa shells. Synthesis of rGO-ZnO was carried out using the Hummer method and thermal reduction. The electrode material was comprehensively characterized using fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy & Energy Dispersive X-ray (SEM-EDX). The photoelectrocatalytic performance of the prepared composite electrodes was evaluated using various electrochemical techniques, including Linear Sweep Voltammetry (LSV), Cyclic Voltammetry (CV), and Multi Pulse Amperometry (MPA). The FTIR analysis of rGO-ZnO exhibited distinct bands corresponding to C-O at 1022 cm-1, C=C at 1600 cm-1, and Zn-O at 455 cm-1. The XRD analysis revealed characteristic peaks at 26.6º, 29.2º, 36.2º, 44.04º, 47.58º, and 64.4º, confirming the presence of key crystalline phases. SEM-EDX analysis of rGO-ZnO revealed a rough surface morphology with bright white and black regions, signifying the coexistence of ZnO and rGO with carbon, oxygen, and zinc contents of 78.98%, 17.46%, and 3.56%, respectively. The investigations involved the photoelectrochemical profiles of methylene blue organic dyes at different concentrations, ranging from 0.5 ppm to 3.0 ppm. The acquired findings offer valuable understanding into the photoelectrocatalytic effectiveness of the composite electrodes containing rGO-ZnO, suggesting their potential use in potential scenarios involving the revitalization of the environment in industrial water systems.

Gross, ultrastructural, and histological characterizations of pecten oculi of the glossy ibis (Plegadis falcinellus): New insights into its scanning electron microscope-energy dispersive X-ray analysis.

The current study shows the first attempts to clarify the gross, ultrastructure, and histological properties of the pecten oculi of the diurnal, visually active glossy ibis, as well as scanning electron microscope-energy dispersive X-ray (SEM-EDX) image analysis (Plegadis falcinellus). The pecten oculi was found on the eyeball's posteroinferior wall, adjacent to the optic nerve in both the craniocaudal and posterio-anterior directions. The plicated quadrilateral black pigmented pecten oculi consisted of a base, 10-12 pleats, and an apex. The base was joined by an elevated ridge and derived from the non-vascular retina, while the apex was not a fused part and was found neighboring the gelatinous vitreous body. The limited interpleat spaces were somewhat wider at the base of the pecten oculi. The outer surface of each highly vascular pecten pleat revealed a tortious coiled formation due to the existence of a considerable number of capillary vessels. The outer pleat surfaces had a vitreopecteneal limiting membrane that segregated the pecten pleats from the vitreous body. The high SEM magnification revealed that there are considerable plentiful hyalocyte cells on the outer surface of the pleats. The SEM-EDX analysis of the elementary formatting of the pecten oculi (at apex, middle, and base) clarified that the carbon represents the highest and a half percent. Furthermore, oxygen represents one-third of all elemental composition in the three regions, while the lowest percentage is calcium. Finally, the pecten oculi characterizations of this migratory bird on the Northern Egyptian shore were associated with their adaptive dietary strategies.

The Synthesis and Characterization of Iron Sand-Based CuFe2O4 as Heavy Metal Ion Adsorbent

This study aimed to synthesize iron sand-based Copper Ferrite (CuFe2O4) using the coprecipitation method. The iron sand was taken from South Cianjur and used as a Fe cation source to synthesize CuFe2O4 nanoparticles. Three composition variations of CuCl2.6H2O and iron sand (Fe3O4) were employed, i.e., 1:1, 1:2, and 2:1. Samples were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy - Energy Dispersive X-Ray (SEM-EDX), and Atomic Adsorption Spectroscopy (AAS). The XRD analysis exhibits three synthesis-phase results: CuFe2O4, Fe2O3, and CuO. The produced CuFe2O4 has two crystal structures: t-CuFe2O4 in 1:2 variation and c-CuFe2O4 in variations 1:1 and 2:1. Adding Cu resulted in smaller crystal size and higher lattice parameters. SEM-EDX analysis of 1:2 sample variation showed a round-shaped particle of 102.57 nm. AAS analysis showed that the increased mole of Cu decreases the heavy metal, including Pb and Mn, adsorption capacity. The largest adsorption capacity was found in the 1:2 (60.698 mg/g).

A preliminary investigation into bacterial viability using scanning electron microscopy-energy-dispersive X-ray analysis: The case of antibiotics.

The metabolic stages of bacterial development and viability under different stress conditions induced by disinfection, chemical treatments, temperature, or atmospheric changes have been thoroughly investigated. Here, we aim to evaluate early metabolic modifications in bacteria following induced stress, resulting in alterations to bacterial metabolism. A protocol was optimized for bacterial preparation using energy-dispersive X-ray (EDX) microanalysis coupled with scanning electron microscopy (SEM), followed by optimizing EDX data acquisition and analysis. We investigated different preparation methods aiming to detect modifications in the bacterial chemical composition at different states. We first investigated Escherichia coli, acquiring data from fresh bacteria, after heat shock, and after contact with 70% ethanol, in order to prove the feasibility of this new strategy. We then applied the new method to different bacterial species following 1 h of incubation with increasing doses of antibiotics used as a stress-inducing agent. Among the different materials tested aiming to avoiding interaction with bacterial metabolites, phosphorous-doped silicon wafers were selected for the slide preparation. The 15 kV acceleration voltage ensured all the chemical elements of interest were excited. A thick layer of bacterial culture was deposited on the silicon wafer providing information from multiple cells and intra-cellular composition. The EDX spectra of fresh, heat-killed, and alcohol-killed E. coli revealed important modifications in magnesium, potassium, and sodium. Those same alterations were detected when applying this strategy to bacteria exposed to antibiotics. Tests based on SEM–EDX acquisition systems would provide early predictions of the bacterial viability state in different conditions, yielding earlier results than culture.

Effect of chloride penetration on electrical resistivity of CNT–CF/cement composites and its application as chloride sensor for reinforced mortar

This study was conducted to investigate the effect of chloride (Cl) penetration on the resistivity of highly conductive composites containing carbon nanotubes (CNTs) and carbon fibers (CFs). First, Cl ions were penetrated into the hardened composite specimens with the application of an electrical charge, and the profiles of the Cl contents, conductivity, hydration, and pore structures were then evaluated. Second, the composite sensors were embedded in a reinforced mortar and immersed in a NaCl solution. Third, the ion distribution in the composite sensor immersed in the NaCl solution was visualized via element mapping using a scanning electron microscopy–energy-dispersive X-ray analysis and an electron probe micro-analyzer. It was found that the resistivity of the composites increased as the Cl penetrated the specimens, and this phenomenon was presumably due to the clogging of the CNT network. The results indicated that the Cl penetration could be monitored by checking the trend of change in the resistance value of multiple sensors over time (trend analysis), and not just by measuring the instantaneous resistance value of a single sensor (deterministic measurement).

Doping of TiO2 Using Metal Waste (Door Key) to Improve Its Photocatalytic Efficiency in the Mineralization of an Emerging Contaminant in an Aqueous Environment

Photocatalysis is an effective advanced oxidation process to mineralize recalcitrant contaminants in aqueous media. TiO2 is the most used photocatalyst in this type of process. To improve the deficiencies of this material, one of the most used strategies has been to dope TiO2 with metallic ions. Chemical reagents are often used as dopant precursors. However, due to the depletion of natural resources, in this work it was proposed to substitute chemical reagents and instead use a metallic residue (door key) as a doping precursor. The materials were synthesized using the sol–gel method and calcined at 400 °C to obtain the crystal structure of anatase. The characterization of the materials was carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), scanning electron microscopy–energy-dispersive X-ray analysis (SEM-EDX) methods X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The results obtained indicate that Cu+/Cu2+ and Zn2+ ions coexist in the support, which modifies the physicochemical properties of TiO2 and improves its photocatalytic efficiency. The synergistic effect of the dopants in TiO2 allowed the mineralization of diclofenac in an aqueous medium when T-DK (1.0) was used as photocatalyst and simulated solar radiation as an activation source.

Pollution and Cleaning of PDMS Pervaporation Membranes after Recovering Ethyl Acetate from Aqueous Saline Solutions

The removal of volatile organic compounds (VOCs) from wastewater containing nonvolatile salts has become an important and interesting case of the application of the pervaporation (PV) process. The aim of this study was to evaluate the influence of salts on the PV removal of ethyl acetate from wastewater using a polydimethylsiloxane (PDMS) membrane. The fouled membrane was then characterized via scanning electron microscopy–energy-dispersive X-ray analysis (SEM–EDX) to investigate salt permeation. The membrane backflushing process was carried out by periodically flushing the permeate side of the tubular membrane. The results demonstrated that salts (NaCl and CaCl2) could permeate through the PDMS membrane and were deposited on the permeate side. The presence of salts in the feed solution caused a slight increase in the membrane selectivity and a decrease in the permeate flux. The flux decreased with increasing salt concentration, and a notable effect occurred at higher feed-salt concentrations. A permeate flux of up to 98.3% of the original flux was recovered when the permeation time and backflushing duration were 30 and 5 min, respectively, indicating that the effect of salt deposition on flux reduction could be mitigated. Real, organic, saline wastewater was treated in a pilot plant, which further verified the feasibility of wastewater PV treatment.

Unveiling the Complexity of Japanese Metallic Threads

In the framework of an extensive survey campaign on a collection of Japanese samurai armors, metallic threads from different parts of the traditional equipment were studied by several analytical techniques. The collection of armors belongs to Museo delle Culture (Lugano, Switzerland) and it is composed of ten elements, which date back from the 15th to 20th century. Metallic threads under study come from six of ten elements of the collection and represent a complex and unique multimaterial, which shows specific characteristics in Japanese tradition (kinran). The multianalytical approach based on ATR-FTIR (Attenuated Total Reflection-Fourier Transform Infrared) spectroscopy and SEM-EDX (Scanning Electron Microscopy, Energy Dispersive X-Ray) analysis, together with a careful observation with optical and digital microscopy, permitted to obtain a complete characterization of materials, which have shown a great variability in metal foils and in organic adhesives (urushi, animal glue, starch). Gold and silver turned out to be not so largely used as scholars thought, while aluminum showed a great diffusion. Within the collection of analyzed armors, the obtained results allowed us for the first time to get a complete comprehension of materials and techniques used by Japanese craftsmen, and to observe differences in the quality of the materials and in manufacture technology over the centuries.

Effects of decontamination protocols on the aesthetic, morphological, and material composition of preformed paediatric crowns

Preformed crowns (PCs) are exposed to potentially infectious bodily fluids during the trial fit; however, whether they can be safely re-used remains uncertain. This study determined the effects of decontamination methods on various PCs. The key criteria examined were aesthetic, morphological, and elemental characteristics. This is a laboratory-based experimental study. Stainless steel, pre-veneered stainless steel, and zirconia PCs underwent either: (a) ultrasonic cleaning with EmPower® followed by steam sterilisation, (b) thermal disinfection in an instrument washer with Asepti® Neutraliser/Asepti® followed by steam sterilisation, or (c) immersion in an ortho-phthalaldehyde (OPA) instrument-level disinfectant. The methods were performed for 1, 5, or 10 cycles, and scanning electron microscopy (SEM); red, green, and blue (RGB) value; and luminosity value were tracked (using a histogram of individual colour reference chips in Adobe Photoshop® ) to assess colour changes, and energy-dispersive X-ray (EDX) spectroscopy to characterise the material composition. Pre-veneered stainless steel crowns showed isolated zones of darkening with loss of luminosity and variations in green and blue values after ultrasonic or thermal washer disinfection combined with steam autoclaving at 5 and 10 cycles. No changes occurred with OPA. Both SEM imaging and EDX analysis identified no changes to crown materials from any of the three reprocessing methods. Reprocessing protocols need to reflect the differing responses of various types of PCs. Repeated steam sterilisation causes slight aesthetic alterations by way of colour instability and loss of luminosity to pre-veneered stainless steel crowns, but no issues with stainless steel or zirconia PCs.

Impregnation of poplar wood with multi-functional composite modifier and induction of in-situ polymerization by heating

Herein, a modified wood with greatly improved mechanical properties and reduced hygroscopicity was successfully prepared. The effects of the impregnation of multi-functional composite modifier on the chemical, thermal and morphological properties of poplar wood were also studied by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analyzer (TGA) and Scanning Electron Microscopy- Energy-Dispersive X-ray Analysis (SEM-EDXA). The multi-functional composite modifier was fabricated by methylolurea, dimethylol dihydroxy ethylene urea (DMDHEU), carbamide and silica sol. Cross-linking reaction happened between the wood cell wall and the multi-functional composite modifier. The position peaks in the XRD pattern didn’t change obviously, which indicated the crystal structure of cellulose was not noticeably affected by the chemical modification. The FT-IR analysis showed that the intensity of hydroxyl (-OH) and carbonyl (C = O) absorption peaks decreased, which was attributed to the -NHCH2OH of the modifier reacted with the hydroxyl and carbonyl of the wood. Meanwhile the Si-O-Si bond and Si-O-C bond formed between the wood structure and silica sol by in-situ polymerization. The TGA curve showed the thermal stability of the modified wood. The micrographs and major elements of the untreated and modified wood were observed by SEM-EDXA.

Structural and elemental characterization of glass and ceramic particles for bone surgery

ObjectiveClinically used bioceramics have been characterized previously with different kinds of methods and comparison of results have proven to be difficult due to varieties of the material properties of interest. Therefore, in this study we compared clinically commonly used bioceramics of hydroxyapatite and carbonate apatite, two bioactive glasses 45S5 and S53P4, and alumina with respect of properties which according to the present knowledge are significant for bone biology. MethodsPhysicochemical properties of the materials were characterized by various methods. Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) was used to analyze the material vibrational features. X-ray Power Diffraction (XRD) was used to characterize the material crystal structure and scanning electron microscopy-energy-dispersive x-ray analysis (SEM-EDXA) was used to evaluate the morphology and size of the materials and to calculate their oxide content. The dissolution behavior of the materials, ion release and pH changes in Tris buffer in a continuous flow-through reaction for 24-hours were determined. The change of the surface of the bioactive glasses by interfacial reaction during the Tris immersion was examined and the thickness of the surface reaction layer of the materials was studied. ResultsSEM examination showed that the particle morphology of BG 45S5, BG S53P4 and alumina particle’s surface was smooth. The surface of HAP was porous, but also CAP showed some surface porosity. An increase in the pH of the immersion solution was observed especially for BG 45S5 and BG S53P4. HAP, CAP and alumina caused only a minor increase in pH. BGs 45S5 and S53P4 showed a rapid initial release of sodium and calcium ions, followed by the release of silicon species. Minor release of sodium ions was registered for HAP, CAP and alumina. Calcium ion release was low but constant over the experimental time while only a minor initial dissolution was measured for HAP. SignificanceThe in vitro study showed differences in the materials’ properties, which are considered to be important for biological suitability and in clinical applications, such as materials tomography, ion release and pH changes.

Rapid and Local Self-Healing Ability of Polyurethane Nanocomposites Using Photothermal Polydopamine-Coated Graphene Oxide Triggered by Near-Infrared Laser.

In this study, we report the self-healing ability of polyurethane (PU) nanocomposites based on the photothermal effect of polydopamine-coated graphene oxide (PDA–rGO). Polydopamine (PDA) was coated on the graphene oxide (GO) surface, while simultaneously reducing GO by the oxidation of dopamine hydrochloride in an alkaline aqueous solution. The PDA–rGO was characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, and scanning electron microscopy–energy-dispersive X-ray analysis. PDA–rGO/PU nanocomposites with nanofiller contents of 0.1, 0.5 and 1 wt% were prepared by ex situ mixing method. The photothermal effect of the PDA–rGO in the PU matrix was investigated at 0.1 W/cm2 using an 808 nm near-infrared (NIR) laser. The photothermal properties of the PDA–rGO/PU nanocomposites were superior to those of the GO/PU nanocomposites, owing to an increase in the local surface plasmon resonance effect by coating with PDA. Subsequently, the self-healing efficiency was confirmed by recovering the tensile stress of the damaged nanocomposites using the thermal energy generated by the NIR laser.

Catalytic wet hydrogen peroxide oxidation of isoeugenol to vanillin using microwave-assisted synthesized metal loaded catalysts

• Supported metal nanoparticles (Cu, W, Mo) on a silica matrix using a one-pot microwave-assisted protocol. • Catalytic activity evaluated in the oxidation of isoeugenol into vanillin. • Moderate conversions, up to 50–60 % (for Cu-MINT). • Acceptable selectivities towards vanillin production (22–45 %). • High catalyst stability (imperceptible decrease of activity after the fourth use). Supported metal nanoparticles (Cu, W, Mo among others) have been stabilized on a silica matrix following an efficient and sustainable one-pot microwave-assisted protocol. The materials synthesized were characterized, mainly, by nitrogen adsorption desorption measurements, X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDS). The materials exhibited large surface area and pore size in the mesopore range. The incorporation of metal particles in the silica matrix was also confirmed with particle size in a wide range between 2 and 52 nm. The catalytic activity of the resulting materials was evaluated in the catalytic wet oxidation of isoeugenol into vanillin using hydrogen peroxide as oxidant. The catalysts shown moderate conversions, up to 50–60 % for Cu-MINT with acceptable selectivity towards vanillin production (22–45 %), obtaining dimers as main side products. The stability of the catalysts was investigated as well, obtaining an imperceptible decrease after the fourth use.