Dispersive X-ray Spectroscopy Images Research Articles

Image enhancement and microstructure characterization of energy dispersive X-ray spectroscopy images of blended cement pastes

Energy dispersive X-ray spectroscopy (EDS) image analysis has been widely used to study the microstructure of cementitious materials, whereas in some cases the efficiency of the characterization suffered from the extremely long time for image acquisition. In this study, we proposed an EDS image analysis methodology including image enhancement, phase extraction, and characterization of reaction products. The guided filter and Logarithm correction were combined and employed to improve the resolvability of low-quality EDS images. Gaussian Mixture Model (GMM) algorithm was applied to segment the unreacted phases and two different groups of reaction products from the enhanced EDS images. Moreover, the spatial distribution and chemical composition of reaction products were characterized using the lineal-path function and simple lineal iterative clustering (SLIC) algorithm. Results showed that low-quality EDS images after enhancing could achieve the comparable performance with high-quality EDS images in terms of the phase proportions. This study offers a practical and effective methodology for enhancing and analyzing the low-quality EDS images, giving insights into the phase assemblage and microstructure evolution of cementitious materials.

Preparation of platinum-free manganese oxide (MnOx) catalyst film for H2O2 decomposition in contact-lens cleaning

A platinum (Pt)-free manganese oxide (MnOx) catalyst film for H2O2 decomposition was prepared on an aluminum (Al) substrate (MnOx/Al) by a hydrothermal impregnation method to decrease the cost of a container used in contact lens cleaning and effectively using Pt materials as other several catalysts. Scanning electron microscopy with energy dispersive X-ray spectroscopy images confirmed that the Al substrate was covered with MnOx. The thickness of the MnOx film was about 300 nm. X-ray diffraction spectra showed that the MnOx film consisted of MnO2 and Mn2O3. The catalytic activity for H2O2 decomposition was estimated by measuring the residual H2O2 concentration, and the target value was ≦100 ppm. The MnOx/Al catalyst was immersed in 35,000 ppm H2O2 solution for 360 min, then the H2O2 concentration decreased to 737 ppm. This result indicated that the MnOx catalyst had a high catalytic activity for H2O2 decomposition but it was not enough for practical use. To improve the catalytic activity, an Al substrate was roughened to increase the specific surface area before preparing an MnOx film. A method with the highest effect of increase in surface roughness was a combination of sandblasting and chemical etching. An MnOx catalyst film was prepared on the roughened Al substrate (MnOx/roughened-Al). When the MnOx/roughened-Al catalyst was immersed in 35,000 ppm H2O2 solution for 360 min, the H2O2 concentration decreased to 38 ppm. When the catalyst was used repeatedly for 10 times, the residual H2O2 concentration was 66 ppm, which indicated that the Pt-free catalyst also had high catalytic durability. These results demonstrated that a roughening was extremely effective in improving both the catalyst activity and durability of a MnOx film catalyst, and a conventional catalyst of a Pt plating film can be replaced with the developed catalyst of the MnOx film on the roughened Al substrate.

Soft X-ray microspectroscopic imaging studies of exfoliated surface between fluoropolymer and Cu plate directly bonded by plasma irradiation with ammonia gas

The F, C, O, and N elemental distribution maps at the exfoliated surfaces of Cu plate after peeling the fluoropolymers from Fluorinated ethylene propylene (FEP)/Cu and Perfluoroalkoxyalkane (PFA)/Cu pieces which were bonded by plasma treatment including amino acid were performed by microscopic synchrotron radiation (SR) spectroscopic imaging measurements. The spatial elemental distribution pattern of exfoliated Cu after peeling PFA/Cu piece was not detectable by scanning electron microscopy with energy dispersive X-ray spectroscopy imaging alone, was revealed by SR-based soft X-ray microspectroscopy. We also obtained the microprobe X-ray fluorescence spectra and microprobe near-edge X-ray absorption fine structure spectra. Based on these measurement results, it is considered that the delamination of FEP/Cu piece mainly caused by resin failure, while the delamination of PFA/Cu is caused by interfacial delamination in addition to resin failure. The Hard X-ray photoelectron spectroscopy was also performed to confirm that the bonding via nitrogen is formed. Our SR-based analyses provided confirmation that fluoropolymers and Cu plates are bonded by N-mediated chemical bonding. The present study insists that the technique and plasma bonding process reported are expected to contribute to the development of new devices and systems consisting of fluoropolymers and metals.

Cytotoxicity effect of nanoparticles of Euphorbia antiquorum on breast cancer cell line

Euphorbia antiquorum was known for its various therapeutic values like anti-inflammatory, anti-diabetic activity etc. Preliminary phytochemicals screening of plant extract disclosed the existence of various important bioactive constituents in hexane, ethanol and aqueous extract of the plant. Aqueous extract of Euphorbia antiquorum was used for silver and copper nanoparticle synthesis. Synthesized silver and copper nanoparticle showed the absorbance line at 422 and 367 nm respectively. Fourier-transform infrared spectroscopy analysis of synthesized nanoparticles reported the presence of phenol groups, amines and esters. Shape and morphology of the synthesized nanoparticles were characterized through Field Emission Scanning Electron Microscopy which showed the spherical shaped nanoparticles. Energy dispersive X-ray spectroscopy images showed the composition of analysed nanoparticles. The antioxidant activity of synthesized silver and copper nanoparticles of Euphorbia antiquorum by hydrogen peroxide scavenging activity method using ascorbic acid as the standard showed effective scavenging activity and indicated the potentiality of the plant as a source of natural antioxidant. Cytotoxicity study of silver nanoparticles showed 73.22% of inhibition at the concentration of 1000 µg/ml whereas copper nanoparticles at the same concentration showed 68.85% of inhibition against breast cancer cell line.

Intelligent framework for mineral segmentation and fluid-accessible surface area analysis in scanning electron microscopy

Imaging is powerful means of sample characterization where mineral abundances and surface areas can be quantified from mineral maps. Images are typically manually processed by domain experts, which is time-consuming, labor intensive, and subjective. Emerging techniques, such as machine learning based image processing, can potentially address these limitations and accelerate image processing but the performance of these models for accurate sample characterization and surface area analysis has not been completely evaluated. This study evaluates the potential of Random Forest and U-Net machine learning methods for mineral characterization and surface area analysis of six sandstone samples. Various input variable sets including filter extracted features, scanning electron microscopy (SEM) backscatter electron (BSE) images and SEM-energy dispersive x-ray spectroscopy images (EDS) images were considered. The evaluation was conducted by providing an intelligent framework that not only evaluates the accuracy of prediction for each pixel but also investigates the accuracy of predicted neighboring pixels. In addition, a new methodology is proposed to distinguish the more susceptible places to dissolution on the surface of a given mineral using a ranked mineral dissolution risk assessment map. The results showed both methods had an acceptable performance with the U-Net model outperforming Random Forest. Both methods showed an improved accuracy when filter extracted features were added to the dataset as input variables. The models’ performance predicting mineral abundances and accessibility agreed well with ground truth data for majority classes (e.g., quartz) compared to minority classes. Finally, the proposed methodology was shown to reliably identify the locations susceptible for dissolution indicated via proposed risk assessment maps. The intelligent segmentation and surface area analysis framework is a promising tool for accelerating the processing of SEM data and reactivity assessment of samples.

Atomic-resolution STEM-EDS studies of cation ordering in Ti-Nb oxide crystals

Ternary metal oxide compounds, such as Ti-Nb and Nb-W oxides, have renewed research interest in energy storage materials because these oxides contain multivalent metal ions that may be able to control the ion transport in solid lithium batteries. One of these oxides is Ti2Nb10O29, which is composed of metal–oxygen octahedra connected through corner-sharing and edge-sharing to form “block structures”. In the early 1970s Von Dreele and Cheetham proposed a metal-atoms ordering in this oxide crystal using Rietveld refined neutron powder diffraction method. Most recent studies on these oxides, however, have not considered cation ordering in evaluating the battery electrode materials. In this paper, by utilizing the latest scanning transmission electron microscopy combined with energy dispersive X-ray spectroscopy imaging technology, the cation chemical ordering in those oxide crystals was directly revealed at atomic resolution.

Ambient energy dispersion and long-term stabilisation of large graphene sheets from graphite using a surface energy matched ionic liquid†

Liquid phase exfoliation (LPE) is the most promising method for scalable graphene production, but conventionally requires significant energy input to break apart layers in the bulk material, introducing defects and limiting production of large, few-layer sheets. In this work, we exfoliated graphene under ambient conditions with minimal external energy input using the surface energy matched ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EMIm Ac), then isolated and characterised the exfoliated material. This method produced large and thin, graphene sheets with size up to 3 μm. Monolayer sheets were identified in samples that had been left undisturbed for 6 months prior to sampling, meaning the graphene sheets suspended in the ionic liquid are stabilized against restacking; to our knowledge, this is the longest period of time large (non-oxidised) graphene monolayers have been suspended in any liquid. Molecular dynamics simulations show the IL cation is enriched at the graphene surface. We postulate this leads to a positive charge on the graphene sheets in EMIM Ac leading to an electrostatic repulsion which contributes to colloidal stability. Strong adsorption of the EMIM cation to graphene is confirmed by energy dispersive X-ray spectroscopy images that show ionic liquid adsorbed to graphene sheets even after washing. Ambient energy exfoliation using ionic liquids offers simple, energy efficient method for producing large, high quality graphene sheets, with long-term stability in the ionic liquid. [Display omitted]

Investigation of organic precursors and plasma mixtures allowing control of carbon passivation when etching HgCdTe in hydrocarbon-based inductively coupled plasmas

Our interest in introducing oxygen and/or nitrogen atoms in CH4/H2/Ar plasma mixtures by means of organic precursors in the place of CH4 or by partly substituting O2 or N2O for H2 and thereby controlling carbon deposition and surface passivation when etching HgCdTe under low substrate bias conditions is investigated in this study. Using in situ ellipsometry, in situ x-ray photoelectron spectroscopy, atomic force microscopy, and secondary electron microscopy (SEM), we show that nitromethane as a precursor and N2O substitution are attractive alternatives for the following: the absence of deposition although no bias is applied, equivalent postetch surface composition, and comparable performances in terms of etch rate and surface roughness for the latter. Such an approach could provide the soft dry etching conditions needed to reduce the pixel pitch of HgCdTe infrared photovoltaic detectors. The mechanisms that allow suppressing carbon deposition upon O2 or N2O substitution in CH4/H2/Ar plasmas are studied by combining plasma diagnostics (optical emission spectroscopy, actinometry, and ion flux measurements) and surface characterizations. First, using Si as a reference substrate, it is shown that deposition is suppressed whenever the O2 and N2O flow rate is half and twice that of CH4, respectively. Moreover, the study reveals that oxygen is the true etch reactant controlling the competition between film growth and etching in both substituted processes, whereas incorporation of nitrogen in the film upon N2O substitution favors its etching kinetics simultaneously. Second, on HgCdTe, deposition of a hydrocarbonitride film is observed at a low N2O/CH4 ratio (∼0.6). SEM and SEM-energy dispersive x-ray spectroscopy imaging suggest that the film nucleates and grows preferentially on regions where the Cd removal mechanisms happen to be less efficient. At a high N2O/CH4 ratio (∼4), oxidation of the HgCdTe surface is observed.

On the chemical composition of psammoma bodies microcalcifications in thyroid cancer tissues

Recently the knowledge of chemical composition of pathological mineralizations is an important topic extensively studied because it could give more in-depth information to understand pathologies themselves and to improve prevention methods. In this work, psammoma bodies (PBs) microcalcifications in thyroid cancer tissue are investigated by different and complementary analytical methods as: micro-Fourier transformed spectroscopy, X-ray fluorescence spectroscopy, Inductively Coupled plasma Optical Emission Spectroscopy (ICP-OES) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy imaging (EDX). For the first time the micro-FTIR analysis of the only inorganic phase isolated from PBs was reported. Signals of the recorded spectrum showed that the main component of the calcifications is the amorphous carbonated calcium phosphate, and the IR spectrum of thyroid PBs is strongly consistent with that of PBs in human ovarian tumors. The XRF and the ICP analysis detected also the presence of iron ad zinc in thyroid PBs. These results are validated by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy imaging (EDX) carried out on tissue samples of the papillary thyroid carcinoma. By these analytical methods magnesium and sodium were detected within PBs while the presence of iron was confirmed by the Perls test. Summarizing the results of applied analytical methods, the main detected elements within the thyroid psammoma bodies are Ca, P, Mg, Na, Fe and Zn. Magnesium and sodium are found in malignant breast cancer microcalcifications, thus they seem correlated to neoplastic transformation. The Fe and Zn elements could give information about the origin of these pathological microcalcifications.

Impact of mineral composition and distribution on the mechanical properties of porous media

Geological sequestration of CO2 in deep saline formations is a promising means of reducing atmospheric CO2 emissions. Once injected, CO2 dissolves into formation brine, lowering pH and creating conditions favorable for mineral dissolution. Cations released from dissolving minerals may create conditions favorable for secondary mineral precipitation, which can result in the long-term mineralogical trapping of injected CO2. These reactions may alter the natural rock mechanical properties, which can affect the safety and efficiency of geological sequestration. This work aims to investigate the impact of mineral composition and distribution on the mechanical properties of porous media. In this study, the mineralogy, mineral distribution, and mechanical properties of samples from Escambia County, AL, are evaluated. The mechanical properties of the rock samples are evaluated using the unconfined compression and indirect tensile tests in the combination with digital image correlation. The mineral composition and distribution are determined through the analysis of scanning electron microscopy backscattered electron and energy dispersive X-ray spectroscopy images of thin sections. These analyses showed that the mechanical properties vary with composition, which may have significant practical consequences for geological sequestration of CO2.

Evaluation of Subconjunctival Remnant Particles after High-frequency Radio-wave Electrosurgery for Conjunctivochalasis.

PurposeTo investigate the clinical manifestations and properties of remnant particles in the subconjunctival space after high-frequency radio-wave electrosurgery for conjunctivochalasis.MethodsWe performed a retrospective, observational case series with in vitro experimental imaging in nine eyes from eight patients who presented with small dark-gray lesions during follow-up after high-frequency radio-wave electrosurgery for conjunctivochalasis. General examination including slit-lamp examination and visual acuity testing was performed preoperatively and postoperatively. During follow-up, we evaluated remnant particles and any other complications including granuloma or conjunctival injection with slit-lamp photography and anterior optical coherence tomography. Coagulation tips were investigated with scanning electron microscope and energy dispersive X-ray spectroscopy to analyze the insulating electrode and assess changes to tips after repeated use.ResultsNone of the patients included in this study experienced any change in visual acuity or major complications postoperatively. Small dark-gray lesions (0.3 to 0.5 mm in size) were observed in the inferior bulbar sub-conjunctival space in the location where high-frequency radio-wave electrosurgery had been performed. Cirrus high-definition optical coherence tomography images revealed focal hyper-reflection with a posterior shadow, suggesting foreign particles. Scanning electron microscopy and energy dispersive X-ray spectroscopy imaging analysis revealed peaks of carbon and fluorine complexes, consistent with the polytetrafluoroethylene coating on the electrode.ConclusionsThere were no instances of inflammatory reaction, particle migration, or major complications due to particles. Physicians should be aware of the possibility of remnant polytetrafluoroethylene particles in subconjunctival tissue when using insulated coagulation tips subjected to repeat sterilization.

Overview of the plasma-surface interaction on limiter surfaces in the startup campaign of Wendelstein 7-X

The first operational campaign of Wendelstein 7-X (W7-X) provided an excellent environment for the study of plasma-surface interaction (PSI) in a stellarator. In situ spectroscopic analysis via a combined visible/infrared camera system and a filterscope system revealed that the primary erosion zone was correlated with the high heat flux regions on the limiter. This analysis matched to where the erosion zone was found in the post-mortem analysis, which was done with scanning electron microscopy/focused ion beam/electron dispersive x-ray spectroscopy imaging. Additionally, a region of prompt deposition was found to the inside of these high heat flux zones. A region of far scrape-off layer (SOL) deposition was found at the edges of the limiter tiles. All deposition regions were identified by their homogeneous, increased oxygen content compared to the pure carbon makeup of the limiters. Poloidal variation of the impinging heat flux follow the imprint of the 3D SOL flux tubes. In how far this reflects in the PSI will require further analysis and modeling.

Multifractal Characterization of Pharmaceutical Hot-Melt Extrudates.

Multifractal geometry has become a powerful tool to describe complex structures in many fields. Our first aim was to combine imaging and multifractal analysis to better understand the microstructure of pharmaceutical extrudates. A second objective was to study erosion/dispersion behavior of the formulations because it would condition release of any drug. Different formulations containing a lipid, a polymer and different silica based inorganic carriers were produced by hot-melt extrusion at various screw speeds. Multifractal analysis was based on scanning electron microscopy/energy dispersive X-Ray spectroscopy images. This microstructural analysis was complemented with dynamic optical imaging of formulation erosion/dispersion behavior. Multifractal analysis indicated that inorganic carrier type and concentration as well as the screw speed affected the microstructure of the extrudates. The aqueous erosion/dispersion study showed that only the type and concentration of inorganic carrier were important. The use of microstructural and dispersion analysis appeared to be complementary to better characterize and understand complex formulations obtained by hot-melt extrusion.

Iodide recovery from thin film transistor liquid crystal display plants by using potassium hydroxide - driven forward osmosis

For the first time, KOH in the waste stream of a thin film transistor liquid crystal displays (TFT-LCD) plant was utilized as a draw solution to recover iodide in the waste stream through forward osmosis (FO). In long-term operation, the pressure-retarded osmosis mode provided concentration efficiency greater than that of the FO mode. The maximum water flux achieved 11.7 LMH at pH 11 of KOH draw solution, and the iodide concentration reached 6.9% for reuse in TFT-LCD plant from the initial iodide concentration of 0.6% after 120h. Analysis of scanning electron microscopy and energy dispersive X-ray spectroscopy images revealed a thin fouling cake layer of KI on the support layer of the membrane. The overall performance of the proposed FO system with KOH as the draw solution indicated that the FO system is promising for concentrating iodide for reuse in TFT-LCD plants. The proposed FO system offers excellent benefits: (1) the liquid discharge is minimal and (2) the cost of the FO system is extremely low because draw solution recovery is not required.

Graphic-textured inclusions in apatite: Evidence for pegmatitic growth in a REE-enriched carbonatitic system

Graphic texture, most common in felsic pegmatites, is documented here in an unusual setting, within apatite of the Hoidas Lake light rare earth element (LREE) deposit, an inferred distal pegmatitic-hydrothermal counterpart of a carbonatite in northern Saskatchewan, Canada. The graphic texture is displayed by vermicular and cuneiform LREE-rich inclusions which define primary growth zones in apatite. Integrated electron microprobe analysis and scanning electron microscope–energy dispersive X-ray spectroscopy imaging document the unusual and heterogeneous compositions of the inclusions, which vary between Ce2O3 + SiO2 (+ ThO2)–dominant and La2O3 + Nd2O3 (+ F)–dominant end members. Here we discuss the formation of these graphic-textured inclusions in the context of models suggested for the formation of graphic quartz–K-feldspar intergrowths in granitic pegmatites, based on the similarity of these features.

INORGANIC SCALE FORMATION AND ITS INDUCED PERMEABILITY IMPAIRMENT DUE TOWATER INCOMPATIBILITY ISSUE DURING THE WATER INJECTION PROCESS

Due to the different natures of formation and injection waters, especially in seawater injection cases, incompatibility may happen within the reservoir and cause supersaturation and precipitation of some salts. This precipitation may reduce the permeability of reservoir rock from the injector vicinity to far deep in the reservoir. This paper investigates a seawater injection project. First, the scale types and amounts due to different mixing ratios are studied employing commercial software. Then, dynamic injection of seawater into carbonate samples saturated with formation water is performed and the induced damages are analyzed. Finally, the types of scales formed within the core samples are analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy imaging. Dynamic conditions may change the behavior of scale formation and precipitation. Therefore, summation of the experimentally-observed scales and the software-predicted ones can lead us to scales happening in reality. The water incompatibility induced permeability damage ratio is characterized by an initial constant permeability period where no damage is induced. After that, it experiences a decrease that stabilizes around 2 pore volumes. The higher the permeability, the longer is the initial constant permeability period and the lower is the final induced permeability damage due to larger pore throats. The final stabilization time points to the situation where all of the core sample lengths have experienced maximum scale formation and precipitation. Overall, the high contrast of seawater and formation water raises the probability of scale formation especially of the sulfate type. Moreover, the extent of damage is much more important than the types of scales which should be investigated in each project.

Epitaxial lateral overgrowth on the air void embedded SiO2 mask for InGaN light-emitting diodes

We fabricated InxGa1−xN multiple quantum well (MQW) light-emitting diodes (LEDs) on an air void embedded SiO2 mask using a simple process (silver (Ag) deposition, SiO2 capping, and high-temperature annealing). Ag was volatilized in the MOCVD process and formed an air void, as revealed by energy dispersive X-ray spectroscopy images. The light output power (at 20 mA) of the LED using epitaxial lateral overgrowth on the SiO2 mask (47.8%) and LED with the air void embedded SiO2 mask (96.8%) are enhanced compared to conventional LEDs. From reflectance measurements, the enhancement of LEDs with an air void embedded SiO2 mask could be mainly explained by the increased high incident angle specular reflectance.