Scanning Electron Microscopy-energy Dispersive X-ray Spectroscopy Analysis Research Articles

Hydration development of blended cement paste with granulated copper slag modified with CaO and Al2O3

Granulated copper slag (GCS) is currently applied to partial cement replacement as a supplementary cementitious material (SCM), but with a low rate due to its low pozzlanic activity. In this contribution we introduce an approach to enhance the reactivity of GCS by modifying the mineral structure using calcium oxide (CaO) and aluminum oxide (Al2O3) both by 10 wt.%, in a molten state. Blended cement pastes were formulated using cement (70 wt.%) and the modified GCS (30 wt.%). The development of hydration heat and strength were examined using isothermal calorimetry and strength tests, respectively. The mineral composition and microstructure of hydration products for different reaction periods were examined using X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). Also, toxicity characteristic leaching procedure (TCLP) was performed on the samples. Results showed an increase in the hydration heat emission rate from the early hydration and the compressive strength of blended cement paste after curing for 28 days, indicating that the addition of CaO and Al2O3 in GCS improves pozzolanic activity. XRD and SEM-EDS analysis indicated that the modified GCS consumed more calcium hydroxide (CH) accompanied by increased generation of calcium silicate hydrate (C–S–H) gels in blended cement with a microstructure containing more gel phases and fewer pores, forming a more compact structure. Leaching of heavy metals of paste samples was lower than Environmental Protection Agency (EPA) limit. It is possible to apply the modified GCS as a sustainable material to promote cleaner production for cement and concrete industries.

SEM-EDS analysis and characterization of glitter and shimmer cosmetic particles

Perpetrators are often aware of commonly used trace evidence in forensic casework, thereby limiting potential transfer during a crime. With the lack of common evidence left behind at a crime scene, consideration of alternative potential evidence is necessary. Glitter and shimmer particles from cosmetic products will potentially transfer from or onto an offender, crime scene, or victim. The transfer of these cosmetic particles during a close personal attack generally goes unnoticed, and thus offenders are unaware of the use of such evidence that may associate a suspect to a crime scene. In this study, 36 glitter and 40 shimmer samples were analyzed using scanning electron microscopy – energy dispersive X-ray spectroscopy (SEM-EDS) whereby characterization schemes were developed to help identify particles potentially transferred during close personal assaults. Samples were classified into 7 glitter and 4 shimmer groups based on elemental composition, and the developed classification models showed high potential to accurately associate or differentiate unknown cosmetic particles collected from a potential crime scene, with cross-validation accuracies ranging from 94 to 100%. Pearson results showed no overlap between inter- and intra-sample correlations, thereby suggesting low possibility of false sample identification. Analysis of variance with post-hoc Tukey test was subsequently performed to determine how well detected elements and element peak ratios differentiated the glitter and shimmer samples, respectively.

Effect of microwave irradiation and conventional calcification roasting with calcium hydroxide on the extraction of vanadium and chromium from high-chromium vanadium slag

A novel high-efficiency method based on microwave irradiation roasting has been proposed to extract valuable metals from minerals. In this study, we employed microwave irradiation and conventional roasting for extracting vanadium and chromium from high-chromium vanadium slag (HCVS) with the additive calcium hydroxide. Differential thermal-thermogravimetry analysis (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy analysis (SEM-EDS), particle size distribution analysis and chemical analyses were used for the characterization and analysis to explain the mechanism of the roasting process. The results shown that roasting temperature, the m(CaO)/m(V2O5) ratio, and roasting time roasted by microwave irradiation and muffle furnace had significantly effect on extraction ratio of vanadium while the effect on the extraction ratio of chromium was relatively small. For the same roasting temperature, the degree of oxidation of HCVS roasted by microwave irradiation was higher than that roasted by muffle furnace. When the m(CaO)/m(V2O5) ratio is low, Mn4V2O9 and CaV2O6 are formed; with the m(CaO)/m(V2O5) ratio increased, Mn4V2O9 and CaV2O6 gradually converted to CaV2O7, and CaCrO3 is formed. Microwave irradiation decreased the particles size and shortened the roasting time. The optimal roasting conditions was determined to be: roasting temperature of 850 °C, m(CaO)/(V2O5) ratio of 0.95, and roasting time of 1.5 h. The maximum extraction ratio of vanadium and chromium roasted by microwave irradiation and muffle furnace were 98.29%, 4.32% and 85.36%, 2.48%, respectively.

Titanium particles: An emerging risk factor for peri-implant bone loss

ObjectiveTo investigate the presence of titanium particles in peri-implant tissues in cases diagnosed with peri-implantitis, and to identify immunological reactions that these particles may elicit. MethodsTen peri-implant tissue biopsies of patients diagnosed clinically and radiographically with peri-implantitis were obtained from the archives of Oral Pathology Centre, University of Otago. The inclusion criteria involves: bleeding on probing, ≥6 mm probing depth and ≥3 mm radiographic bone loss around the dental implant. Peri-implant tissue samples were evaluated using scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS) to identify of sites with/without titanium particles. Antibodies against human transforming growth factor beta 1 (TGF-β1), receptor activator of nuclear factor kappa-B ligand (RANKL), interleukin 33 (IL-33) and cluster of differentiation 68 (CD68) were used to stain the specimens. ImageJ software was used to standardise the sampling area, compare and characterise the inflammatory infiltrate in tissues with/without titanium particles. Inflammatory cytokines positivity was assessed using the immunoreactive scores (IRSs). ResultsLight microscopy and SEM-EDS analysis identified titanium wear particles in 90% of the tissue samples, associated with a mixed chronic inflammatory infiltrate. Quantification analysis of RANKL revealed significantly higher IRS and intensity scores (p < 0.05) in areas containing titanium. High intensity, proportion and IRSs of TGF-β1 and IL-33 were observed in areas with titanium. CD68 had higher IRSs in the absence of titanium particles. ConclusionsSignificant overexpression of the cytokine RANKL was observed, with a trend for over-expression of IL-33 and TGF-B1 in areas with titanium. Further studies with large sample size and appropriate control group for quantification analysis is needed to confirm the role of titanium particles in initiating bone loss.

Mycogenic Selenium Nanoparticles as Potential New Generation Broad Spectrum Antifungal Molecules.

The current challenges of sustainable agricultural development augmented by global climate change have led to the exploration of new technologies like nanotechnology, which has potential in providing novel and improved solutions. Nanotools in the form of nanofertilizers and nanopesticides possess smart delivery mechanisms and controlled release capacity for active ingredients, thus minimizing excess run-off to water bodies. This study aimed to establish the broad spectrum antifungal activity of mycogenic selenium nanoparticles (SeNPs) synthesized from Trichoderma atroviride, and characterize the bioactive nanoparticles using UV–Vis spectroscopy, dynamic light scattering (DLS), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), and high-resolution transmission electron microscopy (HR-TEM). The synthesized nanoparticles displayed excellent in vitro antifungal activity against Pyricularia grisea and inhibited the infection of Colletotrichum capsici and Alternaria solani on chili and tomato leaves at concentrations of 50 and 100 ppm, respectively. The SEM-EDS analysis of the bioactive SeNPs revealed a spherical shape with sizes ranging from 60.48 nm to 123.16 nm. The nanoparticles also possessed the unique property of aggregating and binding to the zoospores of P. infestans at a concentration of 100 ppm, which was visualized using light microscope, atomic force microscopy, and electron microscopy. Thus, the present study highlights the practical application of SeNPs to manage plant diseases in an ecofriendly manner, due to their mycogenic synthesis and broad spectrum antifungal activity against different phytopathogens.

Characterization of Ambient Particulate Matter Sampled at an Active Sand Mine Facility in Northwestern Wisconsin

Concern has arisen about levels of silica in ambient particles near sand mines in Northwestern Wisconsin. Airborne particles released from mining and processing activity may release respirable silica into the air, which can have adverse health effects on individuals exposed to significant quantities. In order to assess these levels of silica, this study developed a parallel analysis using an X-ray diffraction (XRD) and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDS) analysis to test particles in real air samples. Calibrations were constructed for the XRD analysis (following NIOSH Method 7500) with silica standards containing 10 μg – 500 μg respirable silica on filter media with detection limits of 19-28 μg. SEM-EDS methods incorporated identifying the geologic composition of particles using the elemental analysis. Real air samples were collected at a sand mining site using a cascade impactor. Filter substrates were pre-weighed and post-weighed to determine the total dry mass of particles sampled and XRD results show at maximum 16 % of the mass can be attributed to crystalline silica in the samples. An SEM-EDS analysis to categorize the particles geologic classification using ratios of elements shows more than 70% of sampled particles are classified as potassium feldspars. KEYWORDS: Particulate Matter; Sand Mining; Silica; Atmospheric Characterization; XRD; SEM-EDS; Fugitive Dust

Study of Constituents on the Tarnishing Layer of Silver Alloys

Ancient silver artifacts become tarnished when they are exposed to sulfides (H2S) containing environments. As a result, a thin blackish layer is formed on the surface. In spite of the chemical composition, the tarnishing layer has the same color. Nowadays, there is a growing focus on research about tarnish in silver alloys, which allow us to understand its corrosion process, and support decision-making in conservation. However, previous works focused more on sterling silver and on the corrosion problems found on artifacts that are exhibited or stored. This paper studied the constituents of the tarnishing layer in the silver alloys, formed in a (NH4)2S solution, by electrochemical cathodic reduction and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). Ag2S and Cu2S were identified as the main constituents in this layer. SEM-EDS analysis showed a uniform distribution of Cu on the surface and higher weight loss as the copper content increases in the alloy.

Effect of microwave irradiation and conventional calcification roasting with calcium hydroxide on the extraction of vanadium and chromium from high‑chromium vanadium slag

A novel high-efficiency method based on microwave irradiation roasting has been proposed to extract valuable metals from minerals. In this study, we employed microwave irradiation and conventional roasting for extracting vanadium and chromium from high‑chromium vanadium slag (HCVS) with the additive calcium hydroxide. Differential thermal-thermogravimetry analysis (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy analysis (SEM-EDS), particle size distribution analysis and chemical analyses were used for the characterization and analysis to explain the mechanism of the roasting process. The results shown that roasting temperature, the m(CaO)/m(V2O5) ratio, and roasting time roasted by microwave irradiation and muffle furnace had significantly effect on extraction ratio of vanadium while the effect on the extraction ratio of chromium was relatively small. For the same roasting temperature, the degree of oxidation of HCVS roasted by microwave irradiation was higher than that roasted by muffle furnace. When the m(CaO)/m(V2O5) ratio is low, Mn4V2O9 and CaV2O6 are formed; with the m(CaO)/m(V2O5) ratio increased, Mn4V2O9 and CaV2O6 gradually converted to CaV2O7, and CaCrO3 is formed. Microwave irradiation decreased the particles size and shortened the roasting time. The optimal roasting conditions was determined to be: roasting temperature of 850°C, m(CaO)/(V2O5) ratio of 0.95, and roasting time of 1.5h. The maximum extraction ratio of vanadium and chromium roasted by microwave irradiation and muffle furnace were 98.29%, 4.32% and 85.36%, 2.48%, respectively.

Plasma modification of microporous polymer membranes for application in biomimetic dissolution studies

Biorelevant dissolution is an indispensable tool utilized during formulation development and optimization for the prediction of in vivo bioavailability of pharmaceutical agents. Within that framework, membrane-permeation dissolution methodologies are widely used to model drug absorption. The current work evaluates polymer membrane surface modifications for production of biomimetic membranes to be employed in biorelevant dissolution studies. Biomimetic membranes exhibit hydrophilic and hydrophobic properties to simulate the intestinal membrane environment. Low temperature plasma treatment of microporous polyethersulfone (PES), nylon and polypropylene (PP) polymer membranes was applied to produce low energy surface layers with permanent hydrophobic and hydrophilic functionalities. Surface modifications on microporous polymer membranes were achieved by plasma treatments using tetrafluoromethane (CF4), perfluorohexane (C6F14), dichloromethane (DCM) and water (H2O). Surface characterization of treated membranes was evaluated using scanning electron microscopy energy dispersive x-ray spectroscopy (SEM-EDS), water contact angle (CA) and x-ray photoelectron spectroscopy (XPS) techniques. SEM-EDS analysis of polymer membranes treated with fluorinated and chlorinated solvents/gases depicts altered surface morphologies with enriched porosity. SEM-EDS and XPS analyses demonstrate the chemical modification at the surface of treated membranes is strongly influenced by the type of treatment gas or solvent. Results show fluorination as a more effective and less destructive treatment technique. XPS confirmed the presence of elemental fluorine functional groups at the surface of the PES and nylon membranes. Evaluating elemental changes (F/C ratio) from multiple techniques confirms fluorinated plasma treatments are localized to the surface of the membrane and do not significantly affect the bulk properties. In a supplemental study, a detailed comparison of the plasma treated polymer membranes and porcine intestines revealed the biomimetic nature of the modified membranes.

Elaboration of small‐diameter vascular prostheses—Selection of appropriate sterilisation method

ABSTRACTThe aim of study is the elaboration of semi‐biodegradable, multilayered tubular structures as substitutes for the reconstruction of small diameter vascular prostheses (&lt;6 mm). The inert external layer of the prostheses will be fabricated via the melt electrospinning of poly (l‐lactide‐co‐glycolide) (PLGA). The middle layer will be constructed from polypropylene (PP); the first prototype will be produced via melt electrospinning and the second using the melt blowing technique. The general aim of this stage of the research is the selection of a sterilisation technique that is appropriate for semi‐biodegradable, multilayered tubular structures. For this purpose, single tubular structures created via the melt electrospinning of PLGA or PP and melt blown tubular structures of PP were elaborated. The influence of steam, ethylene‐oxide (EO), and radiation sterilisation techniques on the elaborated microstructure of tubular structures was analyzed during this study. The effect of each sterilisation technique was evaluated using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy analysis (SEM/EDS). The changes in average molecular weight (Mw) and crystallinity index (CI) of the PLGA tubular structures after EO and steam sterilisation were evaluated. The EO and steam sterilisation resulted in the complete destruction of PLGA tubular structures. Only the radiation sterilisation (accelerated electrons) did not influence on PLGA tubular structures morphology as well as thermal and chemical properties. FTIR and SEM/EDS analysis indicated that no changes in the chemical properties of PP tubular structures after each sterilisation occurred. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40812.

Characterization of toners and inkjets by laser ablation spectrochemical methods and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy

Detection and sourcing of counterfeit currency, examination of counterfeit security documents and determination of authenticity of medical records are examples of common forensic document investigations. In these cases, the physical and chemical composition of the ink entries can provide important information for the assessment of the authenticity of the document or for making inferences about common source. Previous results reported by our group have demonstrated that elemental analysis, using either Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) or Laser Ablation Induced Breakdown Spectroscopy (LIBS), provides an effective, practical and robust technique for the discrimination of document substrates and writing inks with minimal damage to the document. In this study, laser-based methods and Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) methods were developed, optimized and validated for the forensic analysis of more complex inks such as toners and inkjets, to determine if their elemental composition can differentiate documents printed from different sources and to associate documents that originated from the same printing source. Comparison of the performance of each of these methods is presented, including the analytical figures of merit, discrimination capability and error rates. Different calibration strategies resulting in semi-quantitative and qualitative analysis, comparison methods (match criteria) and data analysis and interpretation tools were also developed. A total of 27 black laser toners originating from different manufacturing sources and/or batches were examined to evaluate the discrimination capability of each method. The results suggest that SEM-EDS offers relatively poor discrimination capability for this set (~70.7% discrimination of all the possible comparison pairs or a 29.3% type II error rate). Nonetheless, SEM-EDS can still be used as a complementary method of analysis since it has the advantage of being non-destructive to the sample in addition to providing imaging capabilities to further characterize toner samples by their particle morphology. Laser sampling methods resulted in an improvement of the discrimination between different sources with LIBS producing 89% discrimination and LA-ICP-MS resulting in 100% discrimination. In addition, a set of 21 black inkjet samples was examined by each method. The results show that SEM-EDS is not appropriate for inkjet examinations since their elemental composition is typically below the detection capabilities with only sulfur detected in this set, providing only 47.4% discrimination between possible comparison pairs. Laser sampling methods were shown to provide discrimination greater than 94% for this same inkjet set with false exclusion and false inclusion rates lower than 4.1% and 5.7%, for LA-ICP-MS and LIBS respectively. Overall these results confirmed the utility of the examination of printed documents by laser-based micro-spectrochemical methods. SEM-EDS analysis of toners produced a limited utility for discrimination within sources but was not an effective tool for inkjet ink discrimination. Both LA-ICP-MS and LIBS can be used in forensic laboratories to chemically characterize inks on documents and to complement the information obtained by conventional methods and enhance their evidential value.

Superficial Distribution and Identification of Antifungal/Antimicrobial Agents on a Modified Tissue Conditioner by SEM‐EDS Microanalysis: A Preliminary Study

This study evaluated the incorporation pattern of antifungal/antimicrobial agents added to a tissue conditioner by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) analysis. The nystatin dosages incorporated into the tissue conditioner (Softone, Bosworth Co., Skokie, IL) powder were 500,000 U (G1) and 1,000,000 U (G2). The addition of miconazole was at 125 mg (G3) and 250 mg (G4), and ketoconazole was at 100 mg (G5) and 200 mg (G6). Chlorhexidine diacetate was blended at levels of 5% (G7) and 10% (G8) w/w of the total amount (6.35 g) of the tissue conditioner. The drug powder concentrations were blended with the tissue conditioner powder at different concentrations before the addition of the tissue conditioner liquid (5 mL) to the mixture. One group (G0) without any drug incorporation was used as control. Specimens (n = 5) (36 x 7 x 6 mm(3)) were plasticized at room temperature for 10 minutes and carbon sputter coated. All specimens were submitted to SEM-EDS analysis. Nystatin and miconazole specimens exhibited particles with irregular shapes and sizes uniformly distributed. Ketoconazole specimens showed small spherical particles with a slight distribution throughout the matrix. Chlorhexidine specimens exhibited irregular particles up to approximately 50 mum in size randomly dispersed within the matrix. Within the limitations of this in vitro study, the modified tissue conditioner showed differences in the particle distribution and size of the antifungal/antimicrobial agent added to the plasticized matrix. Further studies would discriminate the most important particle features that may influence the drug leaching from the plasticized matrix.

A STUDY OF THE EFFECT OF CHRYSOTILE FIBER SURFACE COMPOSITION ON GENOTOXICITY IN VITRO

Chrysotile fibers (NIEHS intermediate length) were treated with ultrapure HCl to alter the fiber surface chemistry without substantially changing fiber morphology or dimensions. The objective of the study was to determine whether fiber surface chemistry is an important variable in fiber genotoxicity in vitro. The modified fibers, along with native chrysotile fibers, were used to challenge Chinese hamster lung fibroblasts (V79) in vitro using the micronucleus induction genotoxicity assay. Fiber dimensions were assessed using scanning electron microscopy by measuring the distribution of fiber lengths in 3 length ranges: less than 3 mum, 3-10 mum, and greater than 10 mum. For both treated and native fiber samples, 500 fibers were examined. Results indicate that acid-treated fibers were about 20% shorter than untreated chrysotile. Surface chemistry alterations were verified by zeta-potential reversal, x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM-EDS) elemental analysis. Scanning Auger spectrometry indicated the presence of Mg, O, and Si in both treated and native chrysotile samples, which confirmed the surface purity of both fiber samples. Both XPS and SEM-EDS analysis demonstrated substantial depletion of Mg from fiber surfaces. Results of the micronucleus assay showed a positive concentration-related response for both samples, with toxicity evident only at the highest concentration. No significant difference was found for the treated and untreated chrysotile samples. These results indicate that the surface chemistry is not an important variable in the in vitro genotoxicity of chrysotile asbestos in V79 cells as detected by the micronucleus assay under the conditions used in this study, and support a model of chemically nonspecific chromosomal and spindle damage effects.