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Microscopy and Microanalysis

Shiladitya Chatterjee, George H Major, Barry M Lunt, Massoud Kaykhaii, Matthew R Linford
Resist lithography is an important microfabrication technique in the electronics industry. In this, patterns are transferred by irradiation onto a photosensitive polymer. SU-8 has emerged as a favorite photoresist for High Aspect Ratio (HAR) lithography, showing high chemical and mechanical stability and biocompatibility. Unfortunately, its poor adhesion to substrates is a drawback, with possible solutions being the use of low-viscosity SU-8, surface modification with a low molecular weight adsorbate like hexamethyldisilazane (HMDS), or a commercial adhesion promotion reagent...
October 17, 2016: Microscopy and Microanalysis
David R Diercks, Brian P Gorman, Johannes J L Mulders
Six precursors were evaluated for use as in situ electron beam-induced deposition capping layers in the preparation of atom probe tomography specimens with a focus on near-surface features where some of the deposition is retained at the specimen apex. Specimens were prepared by deposition of each precursor onto silicon posts and shaped into sub-70-nm radii needles using a focused ion beam. The utility of the depositions was assessed using several criteria including composition and uniformity, evaporation behavior and evaporation fields, and depth of Ga+ ion penetration...
October 17, 2016: Microscopy and Microanalysis
Ben Buse, Stuart Kearns, Charles Clapham, Donovan Hawley
A prototype Peltier thermoelectric cooling unit has been constructed to cool a cold finger on an electron microprobe. The Peltier unit was tested at 15 and 96 W, achieving cold finger temperatures of -10 and -27°C, respectively. The Peltier unit did not adversely affect the analytical stability of the instrument. Heat conduction between the Peltier unit mounted outside the vacuum and the cold finger was found to be very efficient. Under Peltier cooling, the vacuum improvement associated with water vapor deposition was not achieved; this has the advantage of avoiding severe degradation of the vacuum observed when warming up a cold finger from liquid nitrogen (LN2) temperatures...
October 5, 2016: Microscopy and Microanalysis
Manuel Toledano, Fátima S Aguilera, Modesto T López-López, Estrella Osorio, Manuel Toledano-Osorio, Raquel Osorio
The aim of this research was to assess the ability of amalgam restorations to induce amorphous mineral precipitation at the caries-affected dentin substrate. Sound and caries-affected dentin surfaces were subjected to both Zn-free and Zn-containing dental amalgam restorations. Specimens were submitted to thermocycling (100,000 cycles/5°C-55°C, 3 months). Dentin surfaces were studied by atomic force microscopy (nanoroughness), X-ray diffraction, field emission scanning electron microscopy, and energy-dispersive analysis, for physical and morphological surface characterization...
September 29, 2016: Microscopy and Microanalysis
Manuel Dries, Simon Hettler, Tina Schulze, Winfried Send, Erich Müller, Reinhard Schneider, Dagmar Gerthsen, Yuansu Luo, Konrad Samwer
Thin-film phase plates (PPs) have become an interesting tool to enhance the contrast of weak-phase objects in transmission electron microscopy (TEM). The thin film usually consists of amorphous carbon, which suffers from quick degeneration under the intense electron-beam illumination. Recent investigations have focused on the search for alternative materials with an improved material stability. This work presents thin-film PPs fabricated from metallic glass alloys, which are characterized by a high electrical conductivity and an amorphous structure...
September 29, 2016: Microscopy and Microanalysis
Mahrokh Dorri, Stéphane Turgeon, Nicolas Brodusch, Maxime Cloutier, Pascale Chevallier, Raynald Gauvin, Diego Mantovani
Characterization of the topmost surface of biomaterials is crucial to understanding their properties and interactions with the local environment. In this study, the oxide layer microstructure of plasma-modified 316L stainless steel (SS316L) samples was analyzed by a combination of electron backscatter diffraction and electron channeling contrast imaging using low-energy incident electrons. Both techniques allowed clear identification of a nano-thick amorphous oxide layer, on top of the polycrystalline substrate, for the plasma-modified samples...
September 29, 2016: Microscopy and Microanalysis
Liudmila D Iskhakova, Filipp O Milovich, Valery M Mashinsky, Alexander S Zlenko, Sergey E Borisovsky, Evgeny M Dianov
The nature of nanocrystalline inclusions and dopant distribution in bismuth-doped silicate fibers and preforms are studied by scanning and transmission electron microscopy, and energy and wavelength-dispersive X-ray microanalysis. The core compositions are Bi:SiO2, Bi:Al2O3-SiO2, Bi:GeO2-SiO2, Bi:Al2O3-GeO2-SiO2, and Bi:P2O5-Al2O3-GeO2-SiO2. Nanocrystals of metallic Bi, Bi2O3, SiO2, GeO2, and Bi4(GeO4)3 are observed in these glasses. These inclusions can be the reason for the background optical loss in bismuth-doped optical fibers...
September 26, 2016: Microscopy and Microanalysis
Ana I Faustino-Rocha, Ana M Calado, Adelina Gama, Rita Ferreira, Mário Ginja, Paula A Oliveira
Although the rat model of mammary tumors chemically induced by N-methyl-N-nitrosourea (MNU) has been frequently used by several research teams, there is a lack of ultrastructural studies in this field. The main aim of this work was to perform an ultrastructural characterization of MNU-induced mammary tumors in female rats. Some alterations previously reported in human mammary tumors, such as nucleus size and shape, accumulation of heterochromatin in the perinuclear region, and interdigitating cytoplasmic processes between cancer cells were also observed in MNU-induced mammary tumors...
September 22, 2016: Microscopy and Microanalysis
Kazuhiro Kumagai, Akira Kurokawa
No abstract text is available yet for this article.
September 19, 2016: Microscopy and Microanalysis
Irina G Palchikova, Evgenii S Smirnov, Natalia V Kamanina
A test of the qualities of polarizing filters was performed for a set of specimens including a bulk Nicol prism, standard polaroids, and special polyvinyl alcohol (PVA)-iodine thin-film filters coated on both sides by vertically oriented carbon nanotubes. The residual transmission of polarizing filters depending on the incidence angle of polarized light was examined in detail. The superior quality of polarizing film filters treated with carbon nanotubes was found. This fact allows us to propose a new application for polarizing films with carbon nanotubes for a polarizing cover glass...
September 19, 2016: Microscopy and Microanalysis
José Reyes-Gasga, Joseph Hémmerlé, Etienne F Brès
Angstrom resolution images of human tooth enamel (HTE) crystallites were obtained using aberration-corrected high-resolution transmission electron microscopy and atomic-resolution scanning transmission electron microscopy in the modes of bright field, annular dark field, and high-angle annular dark-field. Images show that the central dark line (CDL) defect observed around the center of the HTE crystals is a site for caries formation in the HTE and has a thickness of ~0.2 nm. Results also suggest that the CDL goes through one of the OH- planes...
September 15, 2016: Microscopy and Microanalysis
Lorella Pascolo, Alessandra Gianoncelli, Clara Rizzardi, Martin de Jonge, Daryl Howard, David Paterson, Francesca Cammisuli, Murielle Salomé, Paolo De Paoli, Mauro Melato, Vincenzo Canzonieri
Asbestos bodies are the histological hallmarks of asbestos exposure. Both conventional and advanced techniques are used to evaluate abundance and composition in histological samples. We previously reported the possibility of using synchrotron X-ray fluorescence microscopy (XFM) for analyzing the chemical composition of asbestos bodies directly in lung tissue samples. Here we applied a high-performance synchrotron X-ray fluorescence (XRF) set-up that could allow new protocols for fast monitoring of the occurrence of asbestos bodies in large histological sections, improving investigation of the related chemical changes...
September 13, 2016: Microscopy and Microanalysis
Anders J Barlow, Jose F Portoles, Naoko Sano, Peter J Cumpson
The development of the helium ion microscope (HIM) enables the imaging of both hard, inorganic materials and soft, organic or biological materials. Advantages include outstanding topographical contrast, superior resolution down to <0.5 nm at high magnification, high depth of field, and no need for conductive coatings. The instrument relies on helium atom adsorption and ionization at a cryogenically cooled tip that is atomically sharp. Under ideal conditions this arrangement provides a beam of ions that is stable for days to weeks, with beam currents in the order of picoamperes...
September 13, 2016: Microscopy and Microanalysis
Alfredina Veiga, Dora Martins Teixeira, António J Candeias, José Mirão, Paulo Simões Rodrigues, Jorge Ginja Teixeira
A corrosion product rarely reported in the literature has been found on the copper support of three miniature paintings of the 17th and 18th centuries. This product, which has been identified as dicoppertrihydroxyformate (Cu2(OH)3HCOO), is an unusual basic copper formate found on copper artifacts. The identification and characterization of dicoppertrihydroxyformate was carried out directly over the corroded surface of the objects, using a nondestructive approach, which combines the integrated use of various microanalytical techniques...
September 13, 2016: Microscopy and Microanalysis
Sotiris Psilodimitrakopoulos, Evaggelia Gavgiotaki, Kristallia Melessanaki, Vassilis Tsafas, George Filippidis
In this work, we report that polarization second harmonic generation (PSHG) microscopy, commonly used in biomedical imaging, can quantitatively discriminate naturally aged from fresh starch-based glues used for conservation or restoration of paintings, works of art on paper, and books. Several samples of fresh and aged (7 years) flour and starch pastes were investigated by use of PSHG. In these types of adhesives, widely used in cultural heritage conservation, second harmonic generation (SHG) contrast originates primarily from the starch granules...
September 13, 2016: Microscopy and Microanalysis
Alexandra Roman, Emöke Páll, Mărioara Moldovan, Darian Rusu, Olga Şoriţău, Dana Feştilă, Mihaela Lupşe
Resin composite materials that are used to restore tooth cervical lesions associated with gingival recessions can hamper healing after root coverage surgeries. This study evaluates the in vitro cytotoxic effect of five resin composites (two commercial and three experimental) on oral mesenchymal stem cells (MSCs) and the persistence of stemness properties in high passage MSCs. Sorption and solubility tests were made for all materials. MSCs were isolated from re-entry palatal and periodontal granulation tissues and were characterized and cultured on composite discs...
September 9, 2016: Microscopy and Microanalysis
Anjam Khursheed, Wei Kean Ang
This paper presents a proposal for reducing the final probe size of focused electron/ion beam columns that are operated in a high primary beam current mode where relatively large final apertures are used, typically required in applications such as electron beam lithography, focused ion beams, and electron beam spectroscopy. An annular aperture together with a lens corrector unit is used to replace the conventional final hole-aperture, creating an annular ring-shaped primary beam. The corrector unit is designed to eliminate the first- and second-order geometric aberrations of the objective lens, and for the same probe current, the final geometric aberration limited spot size is predicted to be around a factor of 50 times smaller than that of the corresponding conventional hole-aperture beam...
September 9, 2016: Microscopy and Microanalysis
Saeed Akhtar, Mousa Alkhalaf, Adnan A Khan, Turki M Almubrad
We report ultrastructural features and transmission electron tomography of the dhub lizard (Uromastyx aegyptia) cornea and its adaptation to hot and dry environments. Six corneas of dhub lizards were fixed in 2.5% glutaraldehyde and processed for electron microscopy and tomography. The ultrathin sections were observed with a JEOL 1400 transmission electron microscope. The cornea of the dhub lizard is very thin (~28-30 µm). The epithelium constitutes ~14% of the cornea, whereas the stroma constitutes 80% of the cornea...
August 2016: Microscopy and Microanalysis
Seyfollah Soleimani, Jacob Sukumaran, Koen Douterloigne, Patrick De Baets, Wilfried Philips
In this paper, the change detection of a fast turning specimen is studied at micro-level, whereas the images are acquired without stopping the rotation. In the beginning of the experiment, the imaging system is focused on the surface of the specimen. By starting the rotation of the specimen, the diameter of the specimen changes due to wear, which results in de-focusing of the imaging system. So the amount of blur in the images can be used as evidence of the wear phenomenon. Due to the properties of the microscope, the corners of the frames were dark and had to be cropped...
August 2016: Microscopy and Microanalysis
Dale E Newbury, Nicholas W M Ritchie
Scanning electron microscopy with energy-dispersive spectrometry has been applied to the analysis of various materials at low-incident beam energies, E 0≤5 keV, using peak fitting and following the measured standards/matrix corrections protocol embedded in the National Institute of Standards and Technology Desktop Spectrum Analyzer-II analytical software engine. Low beam energy analysis provides improved spatial resolution laterally and in-depth. The lower beam energy restricts the atomic shells that can be ionized, reducing the number of X-ray peak families available to the analyst...
August 2016: Microscopy and Microanalysis
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