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Microscopy and Microanalysis

Kevin Abbasi, Danqi Wang, Michael A Fusella, Barry P Rand, Amir Avishai
Electron backscattered diffraction (EBSD) is a technique regularly used to obtain crystallographic information from inorganic samples. When EBSD is acquired simultaneously with emitting diodes data, a sample can be thoroughly characterized both structurally and compositionally. For organic materials, coherent Kikuchi patterns do form when the electron beam interacts with crystalline material. However, such patterns tend to be weak due to the low average atomic number of organic materials. This is compounded by the fact that the patterns fade quickly and disappear completely once a critical electron dose is exceeded, inhibiting successful collection of EBSD maps from them...
June 21, 2018: Microscopy and Microanalysis
Shiyun Lin, Bin Chen, Zhongqi Fang, Wei Ye
The work is to investigate the relationships between the microstructures and mechanical behaviors of lobster cuticles and reveal the inner mechanisms of the anisotropic mechanical properties of the cuticles and give the helpful guidance for the design of high-performance man-made composites. First, the tensile mechanical properties of the longitudinal and transverse specimens of the cuticles of American lobsters were tested with a mechanical-testing instrument. It is was found that the fracture strength and elastic modulus of the longitudinal specimens are distinctly larger than those of the transverse specimens...
June 21, 2018: Microscopy and Microanalysis
Brandon P Hedrick, Laurel Yohe, Abby Vander Linden, Liliana M Dávalos, Karen Sears, Alexa Sadier, Stephen J Rossiter, Kalina T J Davies, Elizabeth Dumont
The increased accessibility of soft-tissue data through diffusible iodine-based contrast-enhanced computed tomography (diceCT) enables comparative biologists to increase the taxonomic breadth of their studies with museum specimens. However, it is still unclear how soft-tissue measurements from preserved specimens reflect values from freshly collected specimens and whether diceCT preparation may affect these measurements. Here, we document and evaluate the accuracy of diceCT in museum specimens based on the soft-tissue reconstructions of brains and eyes of five bats...
June 19, 2018: Microscopy and Microanalysis
José Ricardo Carneiro, Paulo Joaquim Almeida, Maria de Lurdes Lopes
The exposure to solar radiation (mainly due to the action of ultraviolet radiation) is one of the main causes for the premature failure of many polymeric materials, including the geotextiles. In this work, a nonwoven polypropylene geotextile (stabilized with a known amount of a hindered amine light stabilizer) was exposed to ultraviolet-aging tests, both in the laboratory (accelerated conditions) and outdoors (natural conditions). The damage occurred in the geotextile (caused by the ultraviolet-aging tests) was evaluated quantitatively (by monitoring changes in its mass per unit area, thickness, and tensile properties) and qualitatively (by scanning electron microscopy)...
June 19, 2018: Microscopy and Microanalysis
Fan Wan, Shixiang Zhao, Rongjun Liu, Changrui Zhang, Thomas J Marrow
Deformation and mechanical damage in a three-dimensional braided carbon fiber reinforced carbon and silicon carbide ceramic composite, subjected to compressive loading, has been studied in situ by laboratory X-ray computed tomography. Dimensional change was measured and damage visualized by digital volume correlation analysis of tomographs. Cracks nucleated from defects within the fiber bundles and tended to propagate along the fiber bundle/matrix interface. For longitudinal compression, parallel to the fiber bundles, the initial elastic modulus decreased with increasing compressive strain while significant transverse tensile strains developed due to distributed cracking...
June 19, 2018: Microscopy and Microanalysis
Colin M MacRae, Anthony E Hughes, James S Laird, A M Glenn, Nicholas C Wilson, Aaron Torpy, Mark A Gibson, Xiaorong Zhou, Nick Birbilis, George E Thompson
Electron and proton microprobes, along with electron backscatter diffraction (EBSD) analysis were used to study the microstructure of the contemporary Al-Cu-Li alloy AA2099-T8. In electron probe microanalysis, wavelength and energy dispersive X-ray spectrometry were used in parallel with soft X-ray emission spectroscopy (SXES) to characterize the microstructure of AA2099-T8. The electron microprobe was able to identify five unique compositions for constituent intermetallic (IM) particles containing combinations of Al, Cu, Fe, Mn, and Zn...
June 18, 2018: Microscopy and Microanalysis
Jian Zhuang, Zhiwu Wang, Zeqing Li, Pengbo Liang, Mugubo Vincent
To solve extended acquisition time issues inherent in the conventional hopping-scanning mode of scanning ion-conductance microscopy (SICM), a new transverse-fast scanning mode (TFSM) is proposed. Because the transverse motion in SICM is not the detection direction and therefore presents no collision problem, it has the ability to move at high speed. In TSFM, the SICM probe gradually descends in the vertical/detection direction and rapidly scans in the transverse/nondetection direction. Further, the highest point that decides the hopping height of each scanning line can be quickly obtained...
June 7, 2018: Microscopy and Microanalysis
Fernando C Castro, Vinayak P Dravid
Cutting-edge research on materials for lithium ion batteries regularly focuses on nanoscale and atomic-scale phenomena. Electron energy-loss spectroscopy (EELS) is one of the most powerful ways of characterizing composition and aspects of the electronic structure of battery materials, particularly lithium and the transition metal mixed oxides found in the electrodes. However, the characteristic EELS signal from battery materials is challenging to analyze when there is strong overlap of spectral features, poor signal-to-background ratios, or thicker and uneven sample areas...
June 7, 2018: Microscopy and Microanalysis
Jafrin F Hussain, Sabitry Bordoloi
This paper deals with the study of the surface morphology of barbels, upper lips, and adhesive discs in four hill stream fish species collected from Basistha River, a torrential river in Guwahati city, Assam, India. The four species belonging to the genus Garra namely, Garra gotyla (Gray, 1830), Garra gravelyi (Annandale, 1919), Garra stenorhynchus (Jerdon, 1849), and Garra nasuta (McClelland, 1838) were collected from the same torrential habitat. These fish revealed anatomical peculiarities in their barbels, lips, and adhesive discs which are believed to help them in adapting to such habitats...
June 2018: Microscopy and Microanalysis
Muhammad Sufyan, Ikram Badshah, Mushtaq Ahmad, Muhammad Zafar, Saraj Bahadur, Neelam Rashid
The present study planned to assess the medicinally important plants in the lower Margalla Hills of Islamabad, Pakistan using scanning electron microscopy of their pollens. Both quantitative and qualitative characters of the pollens were analyzed. The shapes of the pollen were prolate, spheroidal, elliptical, and oblate. Exine sculpturing showed rugulate, scabrate, psilate gemmate, and reticulate ornamentation. The people residing in the rural areas are thought to depend, primarily, on medicinal plant resources for many health care needs...
June 2018: Microscopy and Microanalysis
Shi Yanyan, Guo Yanlei, Zhang Ting, Ding Shigang
BACKGROUND: Helicobacter pylori is a major cause of gastric diseases including gastric cancer. This study was aimed to explore whether hydrotalcite can inhibit H. pylori infection of gastric epithelial cells. METHODS: the gastric epithelial cell line GES-1 and the gastric cancer cell line BGC823 were infected with H. pylori at multiplicities of infections (MOIs) of 50:1 and 100:1. Hydrotalcite was added to cell cultures. Cell apoptosis and cell cycle analysis were performed to measure the situation of cell growth...
June 2018: Microscopy and Microanalysis
Dewen Hou, Tianmo Liu, Meng Shi, Haiming Wen, Haiyan Zhao
The twinning and slip modes of a rolled magnesium alloy sheet were investigated through quasi-in-situ tensile tests that were carried out along the rolling direction at room temperature with a constant strain rate. Scanning electron microscopy and electron backscattered diffraction observations were used to identify activated twinning and slip systems. Schmid factors were calculated to analyze different deformation modes. The analyses show that a small number of {10-12} tensile twins were present during deformation, and these twins resulted from the accommodation of compression along the tensile direction...
June 2018: Microscopy and Microanalysis
Susana Coentro, Rui C da Silva, Cátia Relvas, Teresa Ferreira, José Mirão, Alfonso Pleguezuelo, Rui Trindade, Vânia S F Muralha
This work explores the combination of µ-Raman spectroscopy and scanning electron microscopy with X-ray energy dispersive spectrometry (SEM-EDS) for the study of the glazes in 15th-16th century Hispano-Moresque architectural tiles. These are high lead glazes that can be tin-opacified or transparent, and present five colors: tin-white, cobalt-blue, copper-green, iron-amber, and manganese-brown. They are generally homogenous and mineral inclusions are mostly concentrated in the glaze-ceramic interface. Through SEM-EDS, these inclusions were observed and chemically analyzed, whereas µ-Raman allowed their identification on a molecular level...
June 2018: Microscopy and Microanalysis
Chaoyi Teng, Hendrix Demers, Nicolas Brodusch, Kristian Waters, Raynald Gauvin
A number of techniques for the characterization of rare earth minerals (REM) have been developed and are widely applied in the mining industry. However, most of them are limited to a global analysis due to their low spatial resolution. In this work, phase map analyses were performed on REM with an annular silicon drift detector (aSDD) attached to a field emission scanning electron microscope. The optimal conditions for the aSDD were explored, and the high-resolution phase maps generated at a low accelerating voltage identify phases at the micron scale...
June 2018: Microscopy and Microanalysis
Suoxin Zhang, Jianqiang Qian, Yingzi Li, Yingxu Zhang, Zhenyu Wang
Atomic force microscope (AFM) is an idealized tool to measure the physical and chemical properties of the sample surfaces by reconstructing the force curve, which is of great significance to materials science, biology, and medicine science. Frequency modulation atomic force microscope (FM-AFM) collects the frequency shift as feedback thus having high force sensitivity and it accomplishes a true noncontact mode, which means great potential in biological sample detection field. However, it is a challenge to establish the relationship between the cantilever properties observed in practice and the tip-sample interaction theoretically...
June 2018: Microscopy and Microanalysis
Joen Hermans, Gillian Osmond, Annelies van Loon, Piet Iedema, Robyn Chapman, John Drennan, Kevin Jack, Ronald Rasch, Garry Morgan, Zhi Zhang, Michael Monteiro, Katrien Keune
Using the recently developed techniques of electron tomography, we have explored the first stages of disfiguring formation of zinc soaps in modern oil paintings. The formation of complexes of zinc ions with fatty acids in paint layers is a major threat to the stability and appearance of many late 19th and early 20th century oil paintings. Moreover, the occurrence of zinc soaps in oil paintings leading to defects is disturbingly common, but the chemical reactions and migration mechanisms leading to large zinc soap aggregates or zones remain poorly understood...
June 2018: Microscopy and Microanalysis
Isha Kashyap, Yongmei M Jin, Eric P Vetter, Jerrold A Floro, Marc De Graef
The magnetization configuration of a novel nano-chessboard structure consisting of L10 and L12 phases in a Co40Pt60 alloy is investigated using Lorentz transmission electron microscopy (LTEM) and micro-magnetic simulations. We show high-resolution LTEM images of nano-size magnetic features acquired through spherical aberration correction in Lorentz Fresnel mode. Phase reconstructions and LTEM image simulations are carried out to fully understand the magnetic microstructure. The experimental Fresnel images of the nano-chessboard structure show zig-zag shaped magnetic domain walls at the inter-phase boundaries between L10 and L12 phases...
June 2018: Microscopy and Microanalysis
Andrea Parisini, Stefano Frabboni, Gian Carlo Gazzadi, Rodolfo Rosa, Aldo Armigliato
In this work, we compare the results of different Cliff-Lorimer (Cliff & Lorimer 1975) based methods in the case of a quantitative energy dispersive spectrometry investigation of light elements in ternary C-O-Si thin films. To determine the Cliff-Lorimer (C-L) k-factors, we fabricated, by focused ion beam, a standard consisting of a wedge lamella with a truncated tip, composed of two parallel SiO2 and 4H-SiC stripes. In 4H-SiC, it was not possible to obtain reliable k-factors from standard extrapolation methods owing to the strong CK-photon absorption...
June 2018: Microscopy and Microanalysis
Felix Börrnert, Julian Renner, Ute Kaiser
The electron source brightness is an important parameter of an electron microscope. Reliable and easy brightness measurement routes are not easily found. A determination method for the illumination semi-angle distribution in transmission electron microscopy is even less well documented. Herein, we report a facile measurement route for both entities and demonstrate it on a state-of-the-art instrument. The reduced axial brightness of the FEI X-FEG with a monochromator was determined to be larger than 108 A/(m2 sr V)...
June 2018: Microscopy and Microanalysis
Zhendong Cui, Weige Han
To better understand the formation and evolution of hierarchical crack networks in shales, observations of microscopic damage, and crack growth were conducted using an in situ tensile apparatus inside a scanning electron microscope. An arched specimen with an artificial notch incised into the curved edge was shown to afford effective observation of the damage and crack growth process that occurs during the brittle fracturing of shale. Because this arched specimen design can induce a squeezing effect, reducing the tensile stress concentration at the crack tip, and preventing the brittle shale from unstable fracturing to some extent...
April 2018: Microscopy and Microanalysis
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