Electron Dispersive X-ray Spectroscopy Research Articles

Mold Invasion on the Surface of Wood/Polypropylene Composites Produced from Aqueous Pretreated Wood Particles, Part 1: Date Palm Midrib

The effect of particle pretreatments on the biodeterioration of wood-plastic composites (WPCs) was investigated. WPCs made from untreated and pretreated frond midrib particles of date palm were used. Before the addition of a coupling agent, the wood particles were pretreated or extracted with either cold or hot water and mixed with polypropylene to produce panels, which were then superficially inoculated with an ascomycete’s fungus Trichoderma harzianum T6776. The WPC surfaces were studied using scanning electron microscopy (SEM) and electron dispersive X-ray spectroscopy (EDX) measurements. In comparison with the control, an intensive growth of T. harzianum hyphae was found over the WPC surface manufactured from untreated date palm midrib particles with the colonies clearly visible. The pretreatments of date palm particles reduced the growth of T. harzianum in comparison with the control and untreated particles. The results suggested that particle pretreatments could be a suitable way to limit the growth of molds over WPC surfaces made from date palm midrib.

Nanomolar electrochemical detection of caffeic acid in fortified wine samples based on gold/palladium nanoparticles decorated graphene flakes

Amalgamation of noble metal nanomaterials on graphene flakes potentially paves one way to improve their physicochemical properties. This paper deals with the simultaneous electrochemical deposition of gold and palladium nanoparticles on graphene flakes (Au/PdNPs-GRF) for the sensitive determination of caffeic acid (CA). The physiochemical properties of the prepared Au/PdNPs-GRF was characterized by using numerous analytical techniques such as scanning electron microscopy, electron dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, Raman spectroscopy and electrochemical impedance spectroscopy. The enhanced electrochemical determination of CA at Au/PdNPs deposition on GRF were studied by using cyclic voltammetry and differential pulse voltammetry. In results, Au/PdNPs-GRF electrode exhibited an excellent electrocatalytic activity towards CA with wide linear range and low limit of detection of 0.03–938.97µM and 6nM, respectively. Eventually, the Au/PdNPs-GRF was found as a selective and stable active material for the sensing of CA. In addition, the proposed sensor showed the adequate results in real sample analysis.

Study of Magnetic Micro-Ellipses by Cantilever Sensor

The present study is to clarify the present influences of acid concentration and temperature of caustic hydrothermal method on extracting the titanium dioxide (TiO2) from synthetic rutile waste. In this experimental work, the caustic hydrothermal method comprises two processes: a decomposition and the sulphate process. The extracted titanium is characterized by using a electron dispersive X-ray spectroscopy to specify its chemical composition, field emission scanning electron microscope to determine the morphology and particle size, and lastly it is the X-ray diffraction to analyse the crystallinity of extracted titanium. In this study, we found that both acid concentration and temperature affected the TiO2 growth while the calcination process could improve the crystallinity of extracted titanium.

Auto-combustion preparation and characterization of lead titanate nanoparticles by using different acids and its photocatalyst application

The effect of different acids such as cinnamic acid, salicylic acid, and oxalic acid on size, morphology and uniformity of PbTiO3 nanoparticles prepared via a auto-combustion sol–gel route was investigated. The structural, morphological, and optical properties of as-obtained products were characterized by techniques such as electron dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy and ultraviolet–visible spectroscopy. The estimated band gap shows that this product may be used as a photocatalyst, so the photocatalytic test was performed by photooxidation of methyl orange under UV irradiation and in the presence of PbTiO3. The results showed that methyl orange degradation was about 95% under for 50 min, so the synthesized product can be used as an effective photocatalyst. Vibrating sample magnetometer was used to study the magnetism properties of PbTiO3 sample.

Preparations based on minerals extracts of Calicotome villosa roots and bovine butyrate matter: Evaluation in vitro of their antifungal activity

The use of preparations based on minerals extracts of Calicotomevillosa and butter is born from the misuse of drugs without specific microbiological analyzes. Seventeen different preparations were performed. The antibacterial and antifungal activities were determined on five bacteria and two fungi strains respectively. C. villosa ashes are obtained by incineration of roots plant at 498°C for 4hours. They are analyzed to determine the shape of the particles and the mineral constituents by scanning electronic microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques respectively. The effectiveness of preparations or tablets is measured in solid medium. It allows to measure the diameter of the inhibition zone for the antibacterial activity as well as the diameter of mycelia growth and the critical values (MIC, MFC, IC50 and IC90) for the antifungal activity. Finally, the results are compared to the activity of a commercial positive control aiming to give value of the observed activity. SEM observations reveal the presence of nanoparticles agglomerated with size of about 50nm. The EDX analyzes indicate the presence of Fe, Na, Al, Mg, Si, K, Ca, O2 and C. Among all the results, the preparation (Bs+A) or (Bsd+A) can completely inhibit the growth of two fungal pathogens. The activity of the preparation is faced with the activity of the synthetic fungicide nystatin. The efficacy of the preparation (Bs+A) or (Bsd+A) is higher than that of nystatin against Aspergillussp. and Fusarium sp. The preparation could serve as natural antifungal for the pharmaceutical industry.

Manganese vanadate nanostructure: facile precipitation preparation, characterization, and investigation of their photocatalyst activity

For the first time, we reported the facile synthesis of semiconducting manganese vanadate Mn(VO3)2 nanostructure using manganese(II) chloride dihydrate and ammonium metavanadate as the starting reagent in presence of different surfactants such as sodium dodecyl sulfate, cetyltrimethyl ammonium bromide and polyethylene glycol through precipitation methods. As-prepared products were characterized using X-ray diffraction, scanning electron microscopy, electron dispersive X-ray spectroscopy (EDX), and ultraviolet–visible (UV–Vis) spectroscopy. The photocatalytic activity of Mn(VO3)2 nanostructures were evaluated by degradation of methyl orange in aqueous solution under UV light irradiation. According to the vibrating sample magnetometer, manganese vanadate (Mn(VO3)2) nanostructure indicated a paramagnetic behavior at room temperature.

Formation mechanism of gold-based and gold-free ohmic contacts to AlGaN/GaN heterostructure field effect transistors

To better understand the formation mechanism of ohmic contacts to GaN-based heterostructure field effect transistors, we have compared in detail Ti/Al/Ti/Au and Ti/Al/Ti/TiN contacts. Transmission electron microscopy and electron dispersive X-ray spectroscopy revealed that following anneal, TiN islands penetrated through the AlGaN barrier, as already well known, in the gold-based ohmic contacts but not in the gold-free contacts. We hence conclude that gold facilitates the formation of the TiN islands and propose that the role of gold is extraction of gallium from the semiconductor, providing a gallium depleted region for TiN island formation. For the case of the gold-free contacts, a 8 nm thick semi continuous TiN layer was formed following 900 °C anneal. A 2 nm thick TiN layer was observed in the as deposited samples and remained intact after anneal up to 825 °C. The different ohmic contact formation mechanism of gold-based and gold-free contacts is also manifested by our finding that a discontinuous AlN nitride spacer layer between the barrier and the bulk may lead to non-uniformity in contact behavior across the wafer in the case of gold-free contacts. For gold-based contacts, ohmic contact behavior was uniform across the wafer.

Influence of capping agents additives on morphology of cadmium tungstate nanoparticles and study of their photocatalytic properties

In this investigation, a facile precipitation route has been developed for the preparation of cadmium tungstate (CdWO4) nanoparticles by using cadmium nitrate hexahydrate and sodium tungstate dehydrate as cadmium and vanadate precursor, respectively. The effect of different capping agents such as glycine, valine, and alanine on the morphology and particle size of the products has been investigated. Facile preparation and separation are important features of this route. This work has provided a general, simple, and effective method to control the composition and morphology of cadmium tungstate in aqueous solution, which will be important for inorganic synthesis methodology. The morphology and particle size of products were investigated by scanning electron microscopy images, X-ray diffraction patterns, ultraviolet–visible and electron dispersive X-ray spectroscopy spectroscopy. The photocatalytic characteristics of as-obtained nanocrystalline cadmium tungstate were also examined by degradation of methyl orange dye as water contaminant.

Influence of heat treatment on microstructure and mechanical properties of the interface in an EN AW-6082/1.4310 composite extrusion

The presented paper deals with a unidirectional steel wire reinforced aluminum matrix composite manufactured by composite extrusion. The main objective of this work was to determine the effect of heat treatment, and the influence of long solution annealing times on the composites interface regarding microstructural changes and the resulting interface strength. For evaluation of the microstructure high resolution transmission electron microscope (TEM) investigations accompanied with electron dispersive X-ray spectroscopy (EDX) were performed. It could be shown that diffusion from the steel wire into the aluminum matrix occurs and that the diffusion paths as well as particle formation is influenced by the preceded heat treatment. Diffusion paths in the range of 40–150 nm could be observed for Al, Fe, Cr and Ni. After annealing times over 5 h an extensive growth of an intermetallic reaction layer was found. The mechanical properties of the interface were determined by push-out-tests and tensile tests radial to the interface, which provided the debonding shear strength σdeb and for the latter experiment the interfacial radial strength σIR. It has become apparent that debonding shear strength is highly influenced by matrix properties. In radial tensile tests the failure is predominantly controlled by the chemical bond of the interface. It was shown that interface strength of specimen with small reaction zones of about 3 μm were beneficial for the mechanical behavior in both loading conditions. Longer annealing times showed a drastic decrease of interface shear strength. It was concluded from EDX measurements and in comparison with literature that the reaction zone is dominated by the growth of Al5Fe2 (η-phase).

Laser-induced breakdown spectroscopy for Wendelstein 7-X stellarator limiter tile analysis

Laser-induced breakdown spectroscopy (LIBS) is a well-established elemental composition analysis method as well as one of the most promising candidates for in situ first wall diagnosis of fusion devices. In this work, limiter graphite tiles, which were exposed in the initial operational phase (OP1.1) of the Wendelstein 7-X stellarator to He and H plasma, are analyzed ex situ by LIBS employing a picosecond pulsed laser for the first time and compared with post mortem analysis techniques. Depth profiles of each element and 2D profile of the ratio of H and C atoms on the surface are investigated. Both H content and retention depth on the deposition dominated zone are higher than on the erosion dominated zone due to the formation of C-H co-deposition layer. The results from LIBS are in agreement with those from the cross-sectional scanning electron microscopic image and electron dispersive x-ray spectroscopy.

Evaluation of Solid Minerals Inhibitory Potentials on Mildsteel Corrosion

The use of some solid minerals in the inhibition of mild steel corrosion in acidic media was investigated using the conventional weight loss and hydrogen gas evolution method. Those considered are Talc, Gypsum, Alumina, Iron chromite and Haematite. Scanning electron microscope (SEM) and Electron Dispersive X-ray spectroscopy (EDX) studies revealed the protective effectiveness of the adsorbed film of the mineral extracts on the steel surface. Results obtained indicated the minerals inhibited corrosion of the steel in the order Talc > Gypsum > Haematite > Alumina > Chromite > feldspar as the order of Inhibition efficiency. The resultant effect of solid minerals with Sida acuta plant extract is inhibitorily antagonistic due to induced corrosion rather than improve on the inhibition efficiency. Elements in the minerals got adsorped and reacted with the iron in steel to form a compound of effective protection of the metal against corrosion in its environment.

Fabrication and Enhanced Electrocatalytic Activity of Three-Dimensional Sphere-Stacking PbO2 Coatings Based on TiO2 Nanotube Arrays Substrate for the Electrochemical Oxidation of Organic Pollutants

The three-dimensional sphere-stacking PbO2 coatings based on one-dimensional TiO2-NTs/Ti substrate (3D-sphere PbO2) were prepared without other three-dimensional templates, only by using a simple pulse electrodeposition method. The surface morphology, compositions and crystallographic structure of 3D-sphere PbO2 electrode were investigated fully by using the field emission scanning electron (SEM), X-ray diffractometer (XRD) and energy dispersive X-ray spectroscopy (EDX), respectively. The comparative studies between 3D-sphere PbO2 electrode and traditional flat PbO2 electrode (flat-PbO2) indicated that the 3D-sphere PbO2 electrode with novel structure had smaller grain size. The electrochemical performances of the 3D-sphere PbO2 electrode were carried out by using cyclic voltammograms (CV), linear sweep voltammograms (LSV), electrochemical impedance spectroscopy (EIS) and accelerated service life, respectively. The results show that the 3D-sphere PbO2 electrode has larger electrochemical active surface area, higher oxygen evolution potential and lower charge transfer resistance, leading to it possesses better stable service life on process of degradation than that the flat-PbO2 electrode. Furthermore, the 3D-sphere PbO2 electrode showed the best performance on degradation of phenol in simulated wastewater by bulk electrolysis. The removal efficiency of phenol could reach about 96.5% after 120 min under the optimal current density (30 mA cm−2) at room temperature, which was higher than that by using the flat-PbO2 electrode (73.1%). In addition, the reaction rate constant (k) of 3D-sphere PbO2 electrode degrading phenol solution was 0.0277 min−1 which was 2.56 times larger than that of flat-PbO2 electrode (0.0108 min−1). Summarily, the 3D-sphere electrode is a promising electrode in treating wastewater.

Nanomagnetic Particle Production: Effect of Carbon and Iron Sources

Production of nanomagnetic particles via microbial processes offers the advantage of better biocompatibility for medical applications. However, this process is not widely applied due to the difficulties in cultivating magnetotactic bacteria in the lab. This research explored the possibilities of cultivating magnetotactic bacteria in order to produce nanomagnetic particles in the lab and in particular to find the carbon and iron sources to get the optimum yield of nanomagnetic particles. Experiments were performed as semiaerobic-batch-magnetotactic-bacteria cultivations. The carbon source in the media was varied as: sodium lactate, sodium acetate, and sodium pyruvate. As for the iron source, either Fe-citrate or Fe-quinate was used. Bacterial cell growth was monitored using the turbidometry-gravimetry method, substrate concentration was measured using high performance liquid chromatography (HPLC), while the cellular iron content was measured using electron dispersive X-ray spectroscopy (EDS) and transmission electronic microscopy (TEM). It was observed that cell growth did not correlate with the production of nanomagnetic particles. The bacteria grew best on sodium pyruvate and Fe-quinate, however, the best yield of nanomagnetic particles was obtained from the cultivation with sodium acetate and Fe-quinate. The obtained TEM images confirmed the presence of nanomagnetic particles.

Efficient 2-Nitrophenol Chemical Sensor Development Based on Ce2O3 Nanoparticles Decorated CNT Nanocomposites for Environmental Safety.

Ce2O3 nanoparticle decorated CNT nanocomposites (Ce2O3.CNT NCs) were prepared by a wet-chemical method in basic medium. The Ce2O3.CNT NCs were examined using FTIR, UV/Vis, Field-Emission Scanning Electron Microscopy (FESEM), X-ray electron dispersive spectroscopy (XEDS), X-ray photoelectron spectroscopy (XPS), and powder X-ray diffraction (XRD). A selective 2-nitrophenol (2-NP) sensor was developed by fabricating a thin-layer of NCs onto a flat glassy carbon electrode (GCE, surface area = 0.0316 cm2). Higher sensitivity including linear dynamic range (LDR), long-term stability, and enhanced electrochemical performances towards 2-NP were achieved by a reliable current-voltage (I-V) method. The calibration curve was found linear (R2 = 0.9030) over a wide range of 2-NP concentration (100 pM ~ 100.0 mM). Limit of detection (LOD) and sensor sensitivity were calculated based on noise to signal ratio (~3N/S) as 60 ± 0.02 pM and 1.6×10−3 μAμM-1cm-2 respectively. The Ce2O3.CNT NCs synthesized by a wet-chemical process is an excellent way of establishing nanomaterial decorated carbon materials for chemical sensor development in favor of detecting hazardous compounds in health-care and environmental fields at broad-scales. Finally, the efficiency of the proposed chemical sensors can be applied and utilized in effectively for the selective detection of toxic 2-NP component in environmental real samples with acceptable and reasonable results.

Investigation the magnetic properties and the photocatalytic activity of synthesized Mn7SiO12 nanostructures by green capping agent

In this work, we report the preparation of Mn7SiO12 nanostructures by a rapid and simple method in presence of various carbohydrate sugars as green capping agents. The effect of various carbohydrate sugars such as starch, sucrose and glucose on the shape, uniformity and size of Mn7SiO12 nanostructures were evaluated. Also, the effect of various temperatures and times of reaction were investigated. The synthesized Mn7SiO12 nanostructures were characterized by X-ray diffraction (XRD), Electron Dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), ultraviolet-visible (UV-Vis) spectroscopy and Fourier transform infrared (FT-IR) spectra. Vibrating sample magnetometer (VSM) was applied to study the magnetism properties of Mn7SiO12 nanostructures. Also, the photocatalytic activity of Mn7SiO12 nanostructures was investigated by the photodegradation of methyl violet dye in aqueous solution under UV irradiation.

Reactivity of deposited byproducts generated from ZrO2 atomic layer deposition

In semiconductor manufacturing processes, certain reactive byproducts are known to deposit in the post-process piping and exhaust systems due to the use of extremely reactive chemistries, presenting a significant safety risk. An experimental strategy was developed to evaluate unknown byproducts formed from ZrO2 atomic layer deposition (ALD). Two byproducts were analyzed for this study. These byproducts were generated from the full-scale manufacturing processes using tetrakis (ethylmethylamino)zirconium (TEMAZ) or tris(dimethylamino) (cyclopentadienyl) zirconium (TDCZ) as zirconium precursors. Differential scanning calorimetry and Multiple Mode Calorimetry were first used to characterize the reactivity hazards of the two byproducts. The onset temperature and reaction energy were quantified from both thermal analytical methods. Thermal analysis of the TEMAZ byproduct shows the sample presents significant thermal and pressure hazards, and thus, may lead to an explosion. For the TDCZ byproduct, the risk of a thermal runaway/explosion is low due to its slow kinetics, despite its potential in releasing energy and gases. Subsequently, a series of solid-phase characterization methods, including scanning electron microscopy, electron dispersive x-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), were employed to achieve a thorough understanding of the TEMAZ byproduct, because of its high reactivity. In order to understand the exothermic reactions, the initial byproduct samples were pre-heated and quenched from specific temperatures. These quenched samples were characterized using appropriate analytical methods. Results show that the TEMAZ byproduct is likely to be a mixture of several organic compounds and a zirconium coordination complex. Upon heating, the organic compounds decomposed at a lower temperature range, accompanied by a complete mass loss, whereas the decomposition of the zirconium coordination complex occurred at higher temperatures, resulting in the formation of tetragonal zirconia crystal.

Metallothionein assisted periplasmic lead sequestration as lead sulfite by Providencia vermicola strain SJ2A.

Lead resistant Providencia vermicola strain SJ2A was isolated from the waste of a battery manufacturing industry which could tolerate upto 3.0mM lead nitrate in the minimal medium. Interestingly, this isolate showed presence of a plasmid borne metallothionein gene, bmtA that matched significantly (96%) with that of Pseudomonas aeruginosa. Scanning electron micrographs of bacterial cells exposed to lead revealed a unique alteration in the cell morphology from rods to long inter-connected filaments. On the other hand, electron dispersive X-ray spectroscopy (EDX) clearly indicated no significant lead adsorption therefore, we speculated intracellular sequestration in this bacterial strain. Transmission electron micrographs of the bacterial cells exposed to lead evidently demonstrated periplasmic sequestration of lead which was also supported by Fourier transformed infrared spectroscopic (FTIR) analysis. The bacterium internalised 155.12mg Pb2+/g biomass as determined by atomic absorption spectroscopy. Subsequently, the accumulated lead was identified as lead sulfite by X-ray diffraction studies. Therefore P. vermicola strain SJ2A has potential to bioremediate lead contaminated environmental sites.

Microstructural evolution and magnetic properties of ultrafine solute-atom particles formed in a Cu75–Ni20–Fe5 alloy on isothermal annealing

Microstructural features strongly affect magnetism in nano-granular magnetic materials. In the present work we have investigated the relationship between the magnetic properties and the self-organized microstructure formed in a Cu75–Ni20–Fe5 alloy comprising ferromagnetic elements and copper atoms. High resolution transmission electron microscopy (HRTEM) observations showed that on isothermal annealing at 873 K, nano-scale solute (Fe,Ni)-rich clusters initially formed with a random distribution in the Cu-rich matrix. Superconducting quantum interference device (SQUID) measurements revealed that these ultrafine solute clusters exhibited super-spinglass and superparamagnetic states. On further isothermal annealing the precipitates evolved to cubic or rectangular ferromagnetic particles and aligned along the 〈100〉 directions of the copper-rich matrix. Electron energy-band calculations based on the first-principle Korringa–Kohn–Rostocker (KKR) method were also implemented to investigate both the electronic structure and the magnetic properties of the alloy. Inputting compositions obtained experimentally by scanning transmission electron microscopy–electron dispersive X-ray spectroscopy (STEM–EDS) analysis, the KKR calculation confirmed that ferromagnetic precipitates (of moment 1.07μB per atom) formed after annealing for 2 × 104 min. Magneto-thermogravimetric (MTG) analysis determined with high sensitivity the Curie temperatures and magnetic susceptibility above room temperature of samples containing nano-scale ferromagnetic particles.

Gallium incorporation in InAlN: role of the chamber design and history, and the effects of growth pressure

In this work, we have investigated the non-intentional incorporation of gallium in InAlN layers grown by metal organic vapor phase epitaxy (MOVPE) using two reactors. Atomic force microscopy (AFM) and electron dispersive X-ray spectroscopy (EDS) have been used to characterize the surface morphology and the atomic composition of InAl(Ga)N/GaN structures. The horizontal chamber systematical produces pure ternary layers whereas the close coupled shower head vertical chamber can lead to quaternary alloys. Cleaning the latter significantly reduces the amount of gallium to 1% in the epilayers. Moreover, we show an alternative way to reduce the amount gallium: the use of an intermediate growth pressure typically around 80 Torr drops the inclusion of gallium to 6%. In the presence of such amount of Ga, the growth process appears to be modified and there is a competition between In and Ga for their incorporation, and the Al composition is systematically reduced. The morphology of the layers is also observed to suffer, with the formation of large and closed trenches toward a possible three dimensional growth mode when the layer thickness is increased.

A Comprehensive Study of Intermetallic Compounds in Solar Cell Interconnections and their Growth Kinetics

Intermetallic compounds (IMC) in soldered interconnections influence the reliability of PV modules. Thus, the microstructure of solar cell interconnections and the growth of IMCs are to be investigated in this paper. Sn60Pb40 and Sn41Bi57Ag2 are chosen as alloy coatings of copper interconnectors and semi-automatically soldered to screen-printed front Ag-busbars of industrial mono-crystalline solar cells. The microstructure of the solder bonds is characterized with metallographic cross sections and confocal laser microscopy, as well as scanning electron microscopy and electron dispersive x-ray spectroscopy. The cross section samples are isothermally aged between 85°C to 150°C and for 15 hour to 155 hour to obtain the kinetic parameters of a diffusion-based growth model of the IMCs. The model is used to estimate the IMC thickness after 3000h at 85°C, and after 600 thermal cycles as well as after 25 years in the outdoor location Freiburg, Germany. It is found that extensive microstructural changes take place within the solder bonds during thermal aging. Grain coarsening within the solder matrix, in particular for Sn41Bi57Ag2 solders, is observed, which can lead to an entire Sn depletion of the solder matrix. Moreover, non-uniform Sn penetration and IMC growth at cavities and lead-glass particles of the busbar are observed for both solders, which is discussed in terms of its effect on metallization adhesion. Eventually, simulating the IMC growth for 3000h at 85°C forecasts a 3.7μm thick Ag3Sn IMC at the busbar for the Sn41Bi57Ag2 solder compared to 2.6μm for Sn60Pb40. The prognosis of the IMC thickness after 25 years in Freiburg yields an Ag3Sn thickness of 1.3μm for Sn41Bi57Ag2.