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Microscopy and Microanalysis

Daniel Hadraba, Jiri Janacek, Eva Filova, Frantisek Lopot, Rik Paesen, Ondrej Fanta, Anneliese Jarman, Alois Necas, Marcel Ameloot, Karel Jelen
Fibrillar collagen in tendons and its natural development in rabbits are discussed in this paper. Achilles tendons from newborn (~7 days) to elderly (~38 months) rabbits were monitored in intact (n tendons=24) and microtome sectioned (n tendons=11) states with label-free second harmonic generation microscopy. After sectioning, the collagen fiber pattern was irregular for the younger animals and remained oriented parallel to the load axis of the tendon for the older animals. In contrast, the collagen fiber pattern in the intact samples followed the load axis for all the age groups...
September 20, 2017: Microscopy and Microanalysis
Igor Pantic, Jovana Paunovic, Danijela Vucevic, Tatjana Radosavljevic, Stefan Dugalic, Anita Petkovic, Sanja Radojevic-Skodric, Senka Pantic
Although there are numerous recent works focusing on fractal properties of DNA and chromatin, many issues regarding changes in chromatin fractality during physiological aging remain unclear. In this study, we present results indicating that in mice, there is an age-related reduction of chromatin fractal complexity in a population of spleen follicular cells (SFCs). Spleen tissue was obtained from 16 mice and fixated in Carnoy solution. The youngest animal was newborn, and each animal was exactly 1 month older than the previous...
September 18, 2017: Microscopy and Microanalysis
Kevin P Bohannon, Ronald W Holz, Daniel Axelrod
The refractive index in the interior of single cells affects the evanescent field depth in quantitative studies using total internal reflection (TIR) fluorescence, but often that index is not well known. We here present method to measure and spatially map the absolute index of refraction in a microscopic sample, by imaging a collimated light beam reflected from the substrate/buffer/cell interference at variable angles of incidence. Above the TIR critical angle (which is a strong function of refractive index), the reflection is 100%, but in the immediate sub-critical angle zone, the reflection intensity is a very strong ascending function of incidence angle...
September 18, 2017: Microscopy and Microanalysis
Vipin N Tondare, John S Villarrubia, András E Vlada R
Three-dimensional (3D) reconstruction of a sample surface from scanning electron microscope (SEM) images taken at two perspectives has been known for decades. Nowadays, there exist several commercially available stereophotogrammetry software packages. For testing these software packages, in this study we used Monte Carlo simulated SEM images of virtual samples. A virtual sample is a model in a computer, and its true dimensions are known exactly, which is impossible for real SEM samples due to measurement uncertainty...
September 18, 2017: Microscopy and Microanalysis
Tae-Hoon Kim, Min-Chul Kang, Ga-Bin Jung, Dong Soo Kim, Cheol-Woong Yang
The preparation of transmission electron microscopy (TEM) samples from powders is quite difficult and challenging. For powders with particles in the 1-5 μm size range, it is especially difficult to select an adequate sample preparation technique. Epoxy is commonly used to bind powder, but drawbacks, such as differential milling originating from unequal milling rates between the epoxy and powder, remain. We propose a new, simple method for preparing TEM samples. This method is especially useful for powders with particles in the 1-5 μm size range that are vulnerable to oxidation...
September 13, 2017: Microscopy and Microanalysis
Xianghui Gong, Xixi Zhao, Bin Li, Yan Sun, Meili Liu, Yan Huang, Xiaoling Jia, Jing Ji, Yubo Fan
Both fibronectin (FN) and filamentous actin (F-actin) fibers play a critical role for endothelial cells (ECs) in responding to shear stress and modulating cell alignment and functions. FN is dynamically coupled to the F-actin cytoskeleton via focal adhesions. However, it is unclear how ECs cooperatively remodel their subcellular FN matrix and intracellular F-actin cytoskeleton in response to shear stress. Current studies are hampered by the lack of a reliable and sensitive quantification method of FN orientation...
September 12, 2017: Microscopy and Microanalysis
Juan Wu, Mirna Lerotic, Sean Collins, Rowan Leary, Zineb Saghi, Paul Midgley, Slava Berejnov, Darija Susac, Juergen Stumper, Gurvinder Singh, Adam P Hitchcock
Soft X-ray spectro-tomography provides three-dimensional (3D) chemical mapping based on natural X-ray absorption properties. Since radiation damage is intrinsic to X-ray absorption, it is important to find ways to maximize signal within a given dose. For tomography, using the smallest number of tilt series images that gives a faithful reconstruction is one such method. Compressed sensing (CS) methods have relatively recently been applied to tomographic reconstruction algorithms, providing faithful 3D reconstructions with a much smaller number of projection images than when conventional reconstruction methods are used...
September 12, 2017: Microscopy and Microanalysis
Ida Perrotta, Edoardo Perri
Over the past few decades, remarkable progress has been achieved in terms of understanding the molecular and cellular mechanisms of atherosclerotic vascular calcification and the important role of matrix vesicles in initiating and propagating pathologic tissue mineralization has been widely recognized. Despite these recent advances, however, no definitive data are currently available regarding the texture and composition of the minerals that grow in the vessel wall during the course of the disease. Using different electron microscopy imaging and analysis, we demonstrate that vascular cells can produce and secrete more than one type of matrix vesicles which act as sites for initial mineral deposition independently of their structural features...
September 6, 2017: Microscopy and Microanalysis
Pritesh Parikh, Corey Senowitz, Don Lyons, Isabelle Martin, Ty J Prosa, Michael DiBattista, Arun Devaraj, Y Shirley Meng
The semiconductor industry has seen tremendous progress over the last few decades with continuous reduction in transistor size to improve device performance. Miniaturization of devices has led to changes in the dopants and dielectric layers incorporated. As the gradual shift from two-dimensional metal-oxide semiconductor field-effect transistor to three-dimensional (3D) field-effect transistors (finFETs) occurred, it has become imperative to understand compositional variability with nanoscale spatial resolution...
August 31, 2017: Microscopy and Microanalysis
Takeo Kamino, Toshie Yaguchi, Takahiro Shimizu
Polymer electrolyte fuel cells hold great potential for stationary and mobile applications due to high power density and low operating temperature. However, the structural changes during electrochemical reactions are not well understood. In this article, we detail the development of the sample holder equipped with gas injectors and electric conductors and its application to a membrane electrode assembly of a polymer electrolyte fuel cell. Hydrogen and oxygen gases were simultaneously sprayed on the surfaces of the anode and cathode catalysts of the membrane electrode assembly sample, respectively, and observation of the structural changes in the catalysts were simultaneously carried out along with measurement of the generated voltages...
August 30, 2017: Microscopy and Microanalysis
Kaline P Furlan, Deise R Consoni, Breno Leite, Matheus V G Dias, Aloisio N Klein
In the development of dry self-lubricating composites, not only solid lubricant particle size and distribution are important, but also the correct selection of the solid lubricant characteristics, which should be stable, i.e. not reactive, during the whole processing. In this work, Fe+9 vol% h-BN composites were produced by uniaxial cold compaction and sintering, for which a reaction between h-BN and iron was detected after sintering at 1,150°C. The reaction phase was characterized by optical and scanning electron microscopy and identified by X-ray diffraction and energy-dispersive X-ray spectroscopy...
August 29, 2017: Microscopy and Microanalysis
Pavel Potapov, Elena L Svistunova, Alexander A Gulyaev
Scanning transmission electron microscopy (STEM) in combination with electron energy-loss spectroscopy (EELS) can deliver information about variations of bonding at the nm scale. This is typically performed by analyzing the electron-loss near edge structure (ELNES) of given EELS edges. The present paper demonstrates an alternative way of a bonding examination through monitoring the EELS onset positions. Two conditions are essential for their accurate measurement. One (hardware) is using the dual EELS instrumentation that provides near simultaneous acquisition of low-loss and core-loss spectra...
August 29, 2017: Microscopy and Microanalysis
Yunzhen Zheng, Daniel J Cosgrove, Gang Ning
We have used field emission scanning electron microscopy (FESEM) to study the high-resolution organization of cellulose microfibrils in onion epidermal cell walls. We frequently found that conventional "rule of thumb" conditions for imaging of biological samples did not yield high-resolution images of cellulose organization and often resulted in artifacts or distortions of cell wall structure. Here we detail our method of one-step fixation and dehydration with 100% ethanol, followed by critical point drying, ultrathin iridium (Ir) sputter coating (3 s), and FESEM imaging at a moderate accelerating voltage (10 kV) with an In-lens detector...
August 24, 2017: Microscopy and Microanalysis
Feray Bakan, Meltem Sezen, Merve Gecgin, Yapincak Goncu, Nuran Ay
Calcium phosphate derivatives have been widely employed in medical and dental applications for hard tissue repair, as they are the main inorganic constitution of hard tissue; such as bones and teeth. Owing to their excellent osteoconductive and bioactive properties, hydroxyapatite- (HA) based ceramics are the best candidates of this group for medical, bioscience, and dental applications. However, when replacing a bone or tooth, HA is not able to sustain similar mechanical properties. In this study, to improve the mechanical properties, nanoscale hexagonal boron nitride with different compositional percentages was added to the nano HA to form composites...
August 24, 2017: Microscopy and Microanalysis
Haider Ali, Xinbo Yang, Klaus Weber, Winston V Schoenfeld, Kristopher O Davis
In this study, the cross-section of electron-selective titanium oxide (TiO2) contacts for n-type crystalline silicon solar cells were investigated by transmission electron microscopy. It was revealed that the excellent cell efficiency of 21.6% obtained on n-type cells, featuring SiO2/TiO2/Al rear contacts and after forming gas annealing (FGA) at 350°C, is due to strong surface passivation of SiO2/TiO2 stack as well as low contact resistivity at the Si/SiO2/TiO2 heterojunction. This can be attributed to the transformation of amorphous TiO2 to a conducting TiO2-x phase...
August 15, 2017: Microscopy and Microanalysis
Leo T H de Jeer, Václav Ocelík, Jeff T M De Hosson
A detailed microstructural evaluation was executed on the crystallographic texture as well as the mechanisms for nucleation, phase transformation, and grain growth in a Al0.7CoCrFeNi high-entropy alloy. The microstructure and crystallographic orientations were characterized by electron backscatter diffraction, and the chemical composition variations by energy-dispersive X-ray spectroscopy. The cast Al0.7CoCrFeNi alloy started in the BCC phase and partially transformed into the FCC phase. It was found that the Pitsch orientation relationship (OR) dominates the nucleation mechanism of the FCC phase; however, deviations with respect to the Pitsch OR are observed and are attributed to the differently sized atoms forming an ordered B2 phase in the alloy causing lattice distortions...
August 15, 2017: Microscopy and Microanalysis
Shengkun Yao, Yunbing Zong, Jiadong Fan, Zhibin Sun, Jianhua Zhang, Huaidong Jiang
Ring artifacts are undesirable and complicate the analysis and interpretation of microstructures in synchrotron X-ray microtomography. Here, we propose a new method to improve the image quality of an object by removing the ring artifacts and investigate the efficiency of this process with tomographic images of a dried Tenebrio molitor. In this method, before the tomographic reconstruction, ring artifacts were identified and located in the sinograms as line artifacts. Then, the identified line artifacts were corrected as single point noise via image processing of the original projections...
August 9, 2017: Microscopy and Microanalysis
Priscila L Sequetto, Reggiani V Gonçalves, Aloísio S Pinto, Maria G A Oliveira, Izabel R S C Maldonado, Tânia T Oliveira, Rômulo D Novaes
By using an experimental model of dexamethasone-induced osteoporosis we investigated the effects of different therapeutic schemes combining sodium alendronate (SA) and simvastatin on bone mineral and protein composition, microstructural and mechanical remodeling. Wistar rats were randomized into eight groups: G1: non-osteoporotic; G2: osteoporotic; G3, G4, and G5: osteoporotic+SA (0.2, 0.4, and 0.8 mg/kg, respectively); G6, G7, and G8: osteoporotic+SA (0.2, 0.4, and 0.8 mg/kg, respectively)+simvastatin (0.4, 0...
July 26, 2017: Microscopy and Microanalysis
Zhanhui Su, Han Sun, Man Ao, Chunying Zhao
High-resolution atomic force microscopy (AFM) was used for the in situ evaluation of the anti-inflammatory effects of triptolide on rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) to understand the anti-RA effects of triptolide, based on the morphological and biophysical changes observed in RA-FLS. RA-FLS have been reported to play a primary role in inflammatory bone destruction during the development of RA and thus are regarded as an important target for RA treatment. Triptolide pretreatment significantly inhibited tumor necrosis factor-α-induced expression of the interleukin (IL)-1β, IL-6, and IL-8 genes in MH7A cells...
July 26, 2017: Microscopy and Microanalysis
Rebecca S Jones, Pin H Chang, Tzlil Perahia, Katrina A Harmon, Lorain Junor, Michael J Yost, Daping Fan, John F Eberth, Richard L Goodwin
Vascular stenosis, the abnormal narrowing of blood vessels, arises from defective developmental processes or atherosclerosis-related adult pathologies. Stenosis triggers a series of adaptive cellular responses that induces adverse remodeling, which can progress to partial or complete vessel occlusion with numerous fatal outcomes. Despite its severity, the cellular interactions and biophysical cues that regulate this pathological progression are poorly understood. Here, we report the design and fabrication of a three-dimensional (3D) in vitro system to model vascular stenosis so that specific cellular interactions and responses to hemodynamic stimuli can be investigated...
July 17, 2017: Microscopy and Microanalysis
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