Transmission Electron Microscopy EDX Research Articles

Effects of green decorated AgNPs on lignin-modified magnetic nanoparticles mediated by Cydonia on cecal ligation and puncture-induced sepsis

Abstract Sepsis is a common and deadly syndrome that despite all the progress in its control, the death rate caused by it is high. Sepsis is a serious problem that needs immediate attention and treatment. This infection, especially if it is caused by bacteria resistant to several drugs, causes high mortality. About two-thirds of sepsis cases occur in hospitalized patients. Several factors such as increasing the age of the population, increasing the duration of chronic diseases, high consumption of antibiotics and corticosteroids, use of mechanical devices and intravascular devices play a role in increasing its incidence. We herein demonstrate the biogenic procedure for the in situ immobilizing gold nanoparticles over lignin (Lig)-modified Fe3O4 magnetic nanoparticles mediated by Cydonia leaf extract (Fe3O4@Lig-Ag NPs) and its catalytic activity on the acetylation of alcohols using acetic anhydride and subsequent biological performances. The successful synthesis of Fe3O4@Lig-Ag NPs was assessed using an array of advanced techniques like field emission scanning electron microscopy, fourier transformed infrared spectroscopy, transmission electron microscopy EDX, elemental mapping, vibrating-sample magnetometer, and X-ray diffraction. Cecal ligation and puncture was used for inducing the sepsis model in rats. Several doses of Fe3O4@Lig-Ag NPs (45, 15, and 5 µg/kg) on oxidant–antioxidant, inflammatory mediators mRNA such as IL-1 and TNF-α, and its effects on the levels of expression were assessed in the kidney, liver, duodenum, lung, and stomach. When septic rats kidney, liver, duodenum, lung, and stomach were compared with those of the control group, it was found that Fe3O4@Lig-Ag NPs dose-dependent administration raised glutathione levels and superoxide dismutase activity and significantly reduced the levels of malondialdehyde. The Fe3O4@Lig-Ag NPs (45 µg/kg) indicated greater anti-oxidative effects than the 5 and 15 µg/kg doses for all the assessed parameters. In addition, the expression of TNF-α mRNA in the CLP + 45 µg/kg group was decreased in comparison with the control group. Fe3O4@Lig-Ag NPs reduced oxidative stress by enhancing the free radicals scavenging effects and supporting endogenous antioxidants. The Fe3O4@Lig-Ag NPs potent antioxidant property may be related to the cytokine cascade suppression during sepsis. The above findings offer that Fe3O4@Lig-Ag NPs administration may indicate a modern treatment for the inhibition of liver, kidney, lung, duodenum, and stomach tissues damage caused by septic conditions.

High-Performance Ru 2 P Anodic Catalyst for Alkaline Polymer Electrolyte Fuel Cells

High-Performance Ru ₂ P Anodic Catalyst for Alkaline Polymer Electrolyte Fuel Cells

Nanowire crystals of tantalum nitride grown in ammonium halide fluxes at high pressures

Nanowire crystals of a tantalum nitride phase have been grown from epsilon-tantalum nitride and ammonium halide precursors at high pressures exceeding several gigapascals. Synchrotron x-ray diffraction and Transmission Electron Microscopy (TEM) observations revealed that they had crystallized in an unreported hexagonal structure with lattice parameters of a = 3.050(1) Å and c = 2.909(2) Å. The one-dimensional growth orientation was along the crystallographic [001] direction. Scanning TEM–EDX elemental analyses showed that the nanowire crystals were composed of tantalum and nitrogen with small amounts of oxygen. The presence of the melted ammonium halides combined with supercritical ammonia acting as a reactive flux at high pressure and temperature played a significant role in the nanowire crystal growth. Raman spectroscopy performed on several single crystal nanowires pointed toward metallic properties, and the temperature dependence of the magnetization measured by Superconducting Quantum Interference Device magnetometry suggested a superconducting transition about 6.2 K. The analysis of the compression behavior revealed an incompressible nature, and the bulk modulus was determined to be 363(6) GPa.

Photocatalytic properties of zirconium oxide\u2013zinc oxide nanoparticles synthesised using microwave irradiation

ZrO2–ZnO nanoparticles with different mass concentrations of ZrO2 (1%, 5%, 10%, 20%) were prepared using a two-stage precipitation method with microwave irradiation. The ZrO2–ZnO with 10% of ZrO2 had the highest photocatalytic activity. The obtained material was characterised using XRD, which confirmed a high crystal structure in the synthesised material, and transmission electron microscopy (TEM) analysis, which depicted that micro and nano needle-shaped particles had been obtained and that irregularly shaped nanoparticles were present on the surface of those particles. TEM–EDX analysis confirmed the presence of both ZnO and ZrO2 in the product. FT-IR analyses showed that the positions of peaks related to Zn–O and Zr–O absorption bands did not change in ZrO2–ZnO NPs. The initial concentration of Methylene Blue (MB), the pH of the solution, and the mass of the photocatalyst were investigated to determine the photocatalytic efficiency of the material and the degree of removal of the MB. The highest efficiency (97%) was obtained in the following conditions: 30 mg/dm3 of the MB solution, pH 9 and 70 mg ZrO2–ZnO after 30 min of reaction time under UV irradiation.

Anions and cations distribution in M5+/N3- co-alloyed TiO2 nanotubular structures for photo-electrochemical water splitting

Co-alloyed (M,N) titanium dioxide nanotubes were synthesized by a simple anodization process with M-Ti alloys (M = Ta or Nb), followed by a thermal treatment in ammonia to introduce nitrogen in those nanostructure. The photo-electrochemical performances of these co-alloyed samples was compared with the ones of N doped and undoped TiO2 NTs. Different conditions of thermal treatment under ammonia were studied in order to control the amount of nitrogen introduced in the TiO2 structure and tend to achieve a balance of charges between Ta5+/Nb5+ cations and N3- anions. The structure and composition of these materials were characterized by X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM) EDX mapping. This combination of methods confirm the successful introduction of doping atoms, and allowed us to estimate the amount of M5+ cations and N3- anions in the TiO2 NTs. TEM EDX mapping indicates a heterogeneous distribution of Nb5+ and Ta5+ cations in the nanotubes that can originate from the use of highly concentrated alloys. External quantum efficiency measurements were used to determine the photo-electrochemical activity of our samples in different spectral domains. A significant improvement of activity in the visible region of the solar spectra was observed for co-alloyed TiO2 samples when compared to undoped nanotubes but also when compared to N doped TiO2. The obtained results indicate that the parameters of the NH3 thermal treatments should be finely controlled to improve the conversion efficiency in the visible domain for the co-alloyed samples by introducing a precise amount of N3- in substitution of oxygen in the TiO2 lattice and to avoid the damaging of the nanotubular structure.

Magnetic analysis of a melt-spun Fe-dilute Cu60Au35Fe5 alloy

The magnetic properties of a melt-spun Cu60Au35Fe5 alloy are examined by X-ray diffraction (XRD), magnetic measurements, and transmission electron microscopy (TEM). The XRD pattern of an as-spun sample indicates the formation of a solid solution of Cu and Au with no Fe phase, whereas that of the annealed sample (773K×36ks) shows a small amount of the α-Fe phase because the Fe atoms precipitate during annealing. TEM observations and EDX analysis of the as-spun sample show no distinct Fe-rich domains, implying that some Fe atoms are dissolved in the matrix, and others form very fine magnetic clusters. Moreover, magnetic measurements indicate the presence of magnetic clusters and isolated Fe atoms. The AC magnetic susceptibilities show that the as-spun sample has a sharp cusp around 20K, which is characteristic of spin glass behavior. The simulations of the M–H curves of the as-spun sample measured at 77 and 300K, show that most Fe atoms are dissolved in the matrix as isolated atoms, not as clusters. Additionally, the calculated rate of clustering in the as-spun sample tends to decrease with temperature, suggesting that the magnetic exchange interactions are weak.

Plasma process induced physical damages on multilayered magnetic films for magnetic domain wall motion

The effect of ion irradiation on magnetic domain wall motion (DWM) in a perpendicularly magnetized Co/Ni multilayered film was investigated. The DWM in the Co/Ni multilayered film was sometimes inhibited owing to damage in Co/Ni induced by ion irradiation from Ar/NH3/CO plasma during the etching of the upper layer of a Co/Pt multilayered film depending on the etched depth over Co/Ni. When the DWM was disturbed, modifications of crystallinity were observed by transmission electron microscopy (TEM) near the etched surface region of Co/Ni. Also, the segregation of Pt which was knocked on from the upper layer of Co/Pt, was observed by energy dispersive X-ray line-scan analysis by TEM (TEM–EDX). In contrast to that, the sample which had fine DWM property showed clear lattice image of Co/Ni. A Monte Carlo simulation of Ar+ ion irradiation predicted an atom-displacement range of about 3.5 nm depth from the etching surface when the ion acceleration voltage was 900 V. It was deep enough to degrade the area near the top region of the Co/Ni multilayered magnetic thin film. Eliminating these physical modifications during the etching process would be the key to the fabrication of reliable nonvolatile devices using domain wall motion.

Characterisation of the surface topography, tomography and chemistry of fretting corrosion product found on retrieved polished femoral stems

This study presents the characterisation of the surface topography, tomography and chemistry of fretting corrosion product found on retrieved polished femoral stems. Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FI-IR) were utilised in order to assess the surface morphology of retrieved Metal-on-Metal Total Hip Replacements and surface chemistry of the films found on the surface. Gross slip, plastic deformation and directionality of the surface were extensively seen on the proximal surfaces of the retrievals. A more corrosive phenomenon was observed in the distal regions of the stem, demonstrating a seemingly intergranular attack. Tribochemical reactions were seen to occur within the stem–cement interfaces with tribofilms being observed on the femoral stem and counterpart PMMA bone cement. XPS, TEM–EDX and FT-IR analyses demonstrated that the films present in the stem surfaces were a complex mixture of chromium oxide and amorphous organic material. A comparison between current experimental and clinical literature has been conducted and findings from this study demonstrate that the formation and chemistry of films are drastically influenced by the type of wear or degradation mechanism. Films formed in the stem–cement interface are thought to further influence the biological environment outside the stem–cement interface due to the formation of Cr and O rich films within the interface whilst Co is free to migrate away.

Microscopical analysis of synovial fluid wear debris from failing CoCr hip prostheses

Metal on metal hip joint prostheses are now commonly implanted in patients with hip problems. Although hip replacements largely go ahead problem free, some complications can arise such as infection immediately after surgery and aseptic necrosis caused by vascular complications due to surgery. A recent observation that has been made at Manchester is that some Cobalt Chromium (CoCr) implants are causing chronic pain, with the source being as yet unidentified. This form of replacement failure is independent of surgeon or hospital and so some underlying body/implant interface process is thought to be the problem. When the synovial fluid from a failed joint is examined particles of metal (wear debris) can be found. Transmission Electron Microscopy (TEM) has been used to look at fixed and sectioned samples of the synovial fluid and this has identified fine (< 100 nm) metal and metal oxide particles within the fluid. TEM EDX and Electron Energy Loss Spectroscopy (EELS) have been employed to examine the composition of the particles, showing them to be chromium rich. This gives rise to concern that the failure mechanism may be associated with the debris.

Process and kinetics of bonelike apatite formation on sintered hydroxyapatite in a simulated body fluid

The surfaces of two hydroxyapatites (HA), which have been sintered at different temperatures of 800 and 1200 °C, was investigated as a function of soaking time in simulated body fluid (SBF) using transmission electron microscopy (TEM) attached with energy-dispersive spectrometry (EDX) and laser electrophoresis spectroscopy. The TEM–EDX indicated that after soaking in SBF, both the HAs form bonelike apatite by undergoing the same surface structural change, i.e., formations of a Ca-rich amorphous or nano-crystalline calcium phosphate (ACP) and a Ca-poor ACP, which eventually crystallized into bonelike apatite. Zeta potential characterized by the electrophoresis indicated that during exposure to SBF, the HA surfaces reveal negative surface charge, thereby interacting with the positive calcium ions in the fluid to form the Ca-rich ACP, which gains positive surface charge. The Ca-rich ACP on the HAs then interacts with the negative phosphate ions in the fluid to form the Ca-poor ACP, which stabilizes by being crystallized into bonelike apatite with a low solubility in the SBF. The exposure times for formations of these phases of the Ca-rich ACP, the Ca-poor ACP as well as the apatite were, however, all late on HA sintered at 1200 °C, compared with the HA sintered at 800 °C. This phenomenon was attributed to a lower initial negative surface charge of the HA sintered at 800 °C than of that one sintered at 1200 °C, owing to poverty in surface hydroxyl and phosphate groups which are responsible for the surface negativity of the HA. These indicate that sintered temperature of HA might influence not in terms of the process but in terms of the rate of formation of biologically active bonelike apatite on its surface, through which the HA integrates with living bone.

高純度アルミニウム中の鉄の表面偏析

Surface segregation of iron in high purity aluminum alloys, containing 50 and 280 ppm iron, was investigated by Rutherford back scattering spectroscopy (RBS) and transmission electron microscopy (TEM). The specimens were heat treated at various temperatures ranging from 423 K to 923 K for 72 ks in Ar atmosphere. The surface segregation of iron by heat treatment was detected by RBS measurement. The strongest segregation was observed in the Al–280 ppmFe annealed at 723 K for 72 ks. The surface segregation quantities in Al–50 ppmFe alloy was smaller than those in Al–280 ppmFe alloy, but the degree of segregation (segregation concentration/bulk concentration) in Al–50 ppmFe alloy was larger than that in Al–280 ppmFe alloy. TEM–EDX indicated that almost of iron segregated at the interface between oxide film and the matrix, but a few iron in the oxide films just above aluminum matrix was detected.

Alumina-Supported Cu–Ag Catalysts for Ammonia Oxidation to Nitrogen at Low Temperature

The addition of copper to alumina-supported silver catalysts, by co-incipient wetness impregnation, increased the selectivity to nitrogen during the catalytic oxidation of ammonia at 250°C without significant decrease in activity relative to that of Ag/alumina alone. An increase in selectivity from 80 to circa 95% was observed at 100% ammonia conversion at the optimum Ag/Cu weight ratio (between 1 : 1 and 3 : 1). No increase in activity was observed for mechanical mixtures of Cu/alumina and Ag/alumina catalysts. Based on transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), low-energy ion-scattering spectroscopy, X-ray photoelectron spectroscopy, and Auger analysis, the catalysts consisted of monolayers of copper oxide on alumina upon which silver particles sat. TEM images and EDX analysis showed that silver particles, with a very large size distribution, existed on all catalysts. EDX also revealed the presence of very small (<1 nm) silver dispersed in copper everywhere on the alumina surface. Thus intimate contact between copper and silver on alumina-supported Cu–Ag catalysts existed. No indication of the formation of CuAl2O4 or of Cu–Ag phases was observed. The promotional effect of copper can be explained by a bifunctional mechanism in which the silver component mainly catalyzes ammonia oxidation to NO, the first step of this reaction, and the copper catalyzes the selective catalytic reduction of NO to nitrogen, thus reducing N2O formation on silver.

Segregation of lead in oxide film of high-purity aluminum containing 100 ppm lead

Surface segregation in high-purity Al–100 ppm Pb foil annealed for 4 h at 540 °C was studied mainly by transmission electron microscopy (TEM) observations. TEM–EDX demonstrated that almost of the lead element segregated not to aluminum surface but predominantly to the oxide amorphous film formed just above aluminum surface. The enrichment of lead in the oxide film was about 30 000 fold.