SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Energy-dispersive X-ray spectroscopy

171

This letter describes the use of vertically aligned carbon nanotubes (CNT)-based arrays with estimated 2-nm thick cobalt (Co) nanoparticles deposited inside individual tubes to unravel the possibility of using the unique templates for ultra-high-density low-energy 3-D nano-magneto-electronic devices. The presence of oriented 2-nm thick Co layers within individual nanotubes in the CNT-based 3-D matrix is confirmed through VSM measurements as well as an energy-dispersive X-ray spectroscopy (EDS).

Concepts: Spectroscopy, Carbon, Energy-dispersive X-ray spectroscopy

168

BACKGROUND: Nanotechnology is receiving enormous funding. Very little however is known about the health dangers of this technology so far. Chronic tonsillitis is one of a number of diseases called idiopathic. Among other factors, the tonsils are exposed to suspended particles in inhaled air including nano particles. The objective of this study was to detect and evaluate metallic particles in human tonsil tissue diagnosed with chronic tonsillitis and in amniotic fluid as a comparison. METHODS: Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) was used for identification of solid particles in a total of 64 samples of routinely analyzed biopsy and cytologic material. RESULTS: Almost all samples were found to contain solid particles of various metals. The most frequent, regardless of diagnosis, were iron, chromium, nickel and aluminium. The size, determined using SEM, varied from around 500 nm to 25 µm. The majority formed aggregates of several micrometers in size but there were a significant number of smaller (sub-micrometer or nano-sized) particles present. The incidence of metallic particles was similar in child and adult tissues. The difference was in composition: the presence of several metals in adults was due to occupational exposure. CONCLUSIONS: The presence of metallic particles in pathologically altered tissues may signal an alternative causation of some diseases. The ethiopathogenic explanation of these diseases associated with the presence of nano-sized particles in the organism has emerged into a new field of pathology, nanopathology.

Concepts: Iron, Metal, Scanning electron microscope, Energy-dispersive X-ray spectroscopy, Tonsil, Tonsillectomy, Tonsillitis, Tonsillolith

138

Sintered bodies of Zr2WP2O12 (ZWP) and ZrV0.6P1.4O7 (ZVP) were fabricated, and their linear thermal expansion coefficients (TEC) were found to be -2.92 × 10(-6) and 3.27 × 10(-6) °C(-1), respectively, in the range 25-500 °C. In an attempt to fabricate composites with a zero-thermal-expansion property, sintered ZWP/ZVP composites with ZVP/ZWP volume ratios of 0.5/0.5, 0.53/0.47, 0.55/0.45, and 0.6/0.4 were fabricated. Scanning electron microscopy revealed that sintering of ZVP/ZWP composites progressed well compared with that of ZWP. A porous ZVP/ZWP composite with a relative density of ca. 83% was fabricated at a ZVP/ZWP volume ratio of 0.53/0.47. X-ray diffractometry and energy dispersive X-ray spectrometry clarified that the ZVP/ZWP composite mainly consisted of ZWP and ZVP grains. Thermomechanical analysis confirmed that the ZVP/ZWP composite exhibited very low thermal expansion with a slight hysteresis with a TEC of -0.29 × 10(-7) °C(-1) in the range 25-500 °C.

Concepts: Electron, Fundamental physics concepts, Density, X-ray crystallography, Scanning electron microscope, Energy-dispersive X-ray spectroscopy, Relative density, Coefficient of thermal expansion

62

The roots of the “shy plant” Mimosa pudica L. emit a cocktail of small organic and inorganic sulfur compounds into the environment, including SO2, methylsulfinic acid, pyruvic acid, lactic acid, ethanesulfinic acid, propane sulfinic acid, 2-mercaptoaniline, S-propyl propane 1-thiosulfinate, and thioformaldehyde, an elusive and highly unstable compound never before reported to be emitted by a plant. When soil around the roots is dislodged or when seedling roots are touched, an odor is detected. The perceived odor corresponds to emission of higher amounts of propanesulfenic acid, 2-mercaptoaniline, S-propyl propane 1-thiosulfinate, and phenothiazine. The mechanosensitivity response is selective. Whereas touching the roots with soil or human skin resulted in odor detection, agitating the roots with other materials such as glass did not induce a similar response. Light and electron microscopy studies revealed the presence of microscopic sac-like root protuberances. Elemental analysis of these hairs by energy dispersive X-ray spectroscopy revealed them to contain higher levels of K+ and Cl- compared to the surrounding tissue. Exposing the hairs to stimuli that caused in odor emission resulted in a reduction in the levels of K+ and Cl- in the touched area. The mechanistic implications of the variety of sulfur compounds observed vis-à-vis the pathways for their formation are discussed.

Concepts: Oxygen, Bacteria, Chemical element, Skin, Sulfur, Energy-dispersive X-ray spectroscopy, Sulfur dioxide, Mimosa pudica

27

The advent of simultaneous energy dispersive X-ray spectroscopy (EDS) data collection has vastly improved the phase separation capabilities for electron backscatter diffraction (EBSD) mapping. A major problem remains, however, in distinguishing between multiple cubic phases in a specimen, especially when the compositions of the phases are similar or their particle sizes are small, because the EDS interaction volume is much larger than that of EBSD and the EDS spectra collected during spatial mapping are generally noisy due to time limitations and the need to minimize sample drift. The backscatter electron (BSE) signal is very sensitive to the local composition due to its atomic number (Z) dependence. BSE imaging is investigated as a complimentary tool to EDS to assist phase segmentation and identification in EBSD through examination of specimens of meteorite, Cu dross, and steel oxidation layers. The results demonstrate that the simultaneous acquisition of EBSD patterns, EDS spectra, and the BSE signal can provide new potential for advancing multiphase material characterization in the scanning electron microscope.

Concepts: Electron, Electron microscope, Diffraction, Atom, Scientific techniques, Scanning electron microscope, Energy-dispersive X-ray spectroscopy, Electron backscatter diffraction

27

Cr(VI) is present in the aqueous medium as chromate (CrO(4)(2-)) and bi-chromate (HCrO(4)(-)). Functionalized granular activated carbons (FACs) are used as adsorbents in the treatment of wastewaters containing hexavalent chromium. The FACs are prepared by chemical modifications of granular activated carbons (GACs) using functionalizing agents like HNO(3), HCl and HF. The Brunauer, Emmett and Teller surface areas of FAC-HCl (693.5m(2)/g), FAC-HNO(3) (648.8m(2)/g) and FAC-HF (726.2m(2)/g) are comparable to the GAC (777.7m(2)/g). But, the adsorption capacity of each of the FAC-HNO(3), FAC-HCl and FAC-HF is found to be higher than the GAC. The functional groups play an important role in the adsorption process and pH has practically no role in this specific case. The FACs have hydrophilic protonated external surfaces in particular, along with the functional surface sites capable to make complexes with the CrO(4)(2-) and HCrO(4)(-) present. Surface complex formation is maximized in the order FAC-HNO(3)>FAC-HF>FAC-HCl, in proportion to the total surface acidity. This is also confirmed by the well-known pseudo second-order kinetic model. Physi-sorption equilibrium isotherms are parameterized by using standard Freundlich and Langmuir models. Langmuir fits better. The formation of surface complexes with the functional groups and hexavalent chromium is also revealed in the images of field emission scanning electron micrograph; energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy analysis after adsorption. The intra-particle diffusion is not the only rate-controlling factor. The Boyd’s film diffusion model fits very well with R(2) as high as 98.1% for FAC-HNO(3). This result demonstrates that the functionalization of the GAC by acid treatments would increase the diffusion rate, predominantly with a boundary layer diffusion effect.

Concepts: Spectroscopy, Carbon dioxide, Carbon, Adsorption, Scanning electron microscope, Energy-dispersive X-ray spectroscopy, Fourier transform spectroscopy, Activated carbon

24

The purpose of this study was to investigate the corrosion behavior of 10 different high noble gold-based dental alloys, used for prosthodontic retention elements, according to ISO 10271. Samples of 10 high-noble and noble gold-based dental alloys were subjected to: (i) static immersion tests with subsequent analysis of ion release for eight different elements using mass spectrometry; (ii) electrochemical tests, including open-circuit potential and potentiodynamic scans; and (iii) scanning electron microscopy, followed by energy-dispersive X-ray microscopy. The results were analyzed using one-way ANOVA and Sidak multiple-comparisons post-hoc test at a level of significance of α = 0.05. Significant differences were found among the 10 alloys studied for all ions (P < 0.001). The potentiodynamic analysis showed values from -82.5 to 102.8 mV for the open-circuit potential and from 566.7 to 1367.5 mV for the breakdown potential. Both the open-circuit and the breakdown potential varied considerably among these alloys. Scanning electron microscopy analysis confirmed the existence of typically small-diameter corrosion defects, whilst the energy-dispersive X-ray analysis found no significant alteration in the elemental composition of the alloys. The results of this study reveal the variability in the corrosive resistance among the materials used for retention elements in prosthodontics.

Concepts: Electron, Electron microscope, Atom, Ion, Analysis of variance, Scanning electron microscope, Energy-dispersive X-ray spectroscopy, American Dental Association

20

The catalytic and optical properties of metal nanoparticles can be combined to create platforms for light-driven chemical energy storage and enhanced in-situ reaction monitoring. However, the heavily damped plasmon resonances of many catalytically active metals (e.g. Pt, Pd) prevent this dual functionality in pure nanostructures. The addition of catalytic metals at the surface of efficient plasmonic particles thus presents a unique opportunity if the resonances can be conserved after coating. Here, nanometer resolution electron-based techniques (electron energy loss, cathodoluminescence, and energy dispersive X-ray spectroscopy) are used to show that Au particles incorporating a catalytically active but heavily damped metal, Pd, sustain multiple size-dependent localized surface plasmon resonances (LSPRs) that are narrow and strongly localized at the Pd-rich tips. The resonances also couple with a dielectric substrate and other nanoparticles, establishing that the full range of plasmonic behavior is observed in these multifunctional nanostructures despite the presence of Pd.

Concepts: Nanoparticle, Optics, Chemical reaction, Light, Surface plasmon resonance, Plasmon, Energy-dispersive X-ray spectroscopy, Plasma oscillation

8

Cellular complexity is unraveled at nanometer resolution using electron microscopy (EM), but interpretation of macromolecular functionality is hampered by the difficulty in interpreting grey-scale images and the unidentified molecular content. We perform large-scale EM on mammalian tissue complemented with energy-dispersive X-ray analysis (EDX) to allow EM-data analysis based on elemental composition. Endogenous elements, labels (gold and cadmium-based nanoparticles) as well as stains are analyzed at ultrastructural resolution. This provides a wide palette of colors to paint the traditional grey-scale EM images for composition-based interpretation. Our proof-of-principle application of EM-EDX reveals that endocrine and exocrine vesicles exist in single cells in Islets of Langerhans. This highlights how elemental mapping reveals unbiased biomedical relevant information. Broad application of EM-EDX will further allow experimental analysis on large-scale tissue using endogenous elements, multiple stains, and multiple markers and thus brings nanometer-scale ‘color-EM’ as a promising tool to unravel molecular (de)regulation in biomedicine.

Concepts: DNA, Electron, Islets of Langerhans, Pancreas, Molecule, Chemistry, Chemical bond, Energy-dispersive X-ray spectroscopy

6

After the March 11, 2011, nuclear reactor meltdowns at Fukushima Dai-ichi, 180 samples of Japanese particulate matter (dusts and surface soils) and 235 similar U.S. and Canadian samples were collected and analyzed sequentially by gamma spectrometry, autoradiography, and scanning electron microscopy with energy dispersive X-ray analysis. Samples were collected and analyzed over a five-year period, from 2011 to 2016. Detectable levels of (134)Cs and (137)Cs were found in 142 of 180 (80%) Japanese particulate matter samples. The median radio-cesium specific activity of Japanese particulate samples was 3.2kBqkg(-1)±1.8kBqkg(-1), and the mean was 25.7kBqkg(-1) (σ=72kBqkg(-1)). The U.S. and Canadian mean and median radio‑cesium activity levels were <0.03kBqkg(-1). U.S. and Canadian samples had detectable (134)Cs and (137)Cs in one dust sample out of 32 collected, and four soils out of 74. The maximum US/Canada radio-cesium particulate matter activity was 0.30±0.10kBqkg(-1). The mean in Japan was skewed upward due to nine of the 180 (5%) samples with activities >250kBqkg(-1). This skewness was present in both the 2011 and 2016 sample sets. >300 individual radioactively-hot particles were identified in samples from Japan; composed of 1% or more of the elements cesium, americium, radium, polonium, thorium, tellurium, or strontium. Some particles reached specific activities in the MBqμg(-1) level and higher. No cesium-containing hot particles were found in the U.S. sample set. Only naturally-occurring radionuclides were found in particles from the U.S. background samples. Some of the hot particles detected in this study could cause significant radiation exposures to individuals if inhaled. Exposure models ignoring these isolated hot particles would potentially understate human radiation dose.

Concepts: Ionizing radiation, Median, Japan, Mean, Standard deviation, Skewness, Energy-dispersive X-ray spectroscopy, Dust