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Journal of Microscopy

Y Yao, X He, C Liu, Jianqiang Zhu
A new coded splitting imaging technique is proposed to reconstruct the complex amplitude of a light field iteratively using a single-shot measurement. In this technique, a specially designed coded splitting plate is adopted to diffract the illuminating beam into multiple beams of different orders and code their wavefronts independently and differently. From the diffraction pattern array recorded on the detector plane, both the modulus and phase distributions of the illuminating beam can be reconstructed iteratively using known transmission functions of different orders of the coded splitting plate...
November 10, 2017: Journal of Microscopy
Keiichi Moriguchi
When polymorphonuclear leukocytes (PMNs) phagocytose opsonised zymosan particles (OPZ), free radicals and reactive oxygen species (ROS) are formed in the phagosomes. ROS production is mediated by NADPH oxidase (Nox), which transfers electrons in converting oxygen to superoxide (O2(-) ). Nox-generated O2(-) is rapidly converted to other ROS. Free radical-forming secretory vesicles containing the Nox redox center flavocytochrome b558, a membrane protein, and azurophil granules with packaged myeloperoxidase (MPO) have been described...
November 10, 2017: Journal of Microscopy
Brian Dorvel, Praveenkumar Boopalachandran, Ida Chen, Andrew Bowling, Kerry Williams, Steve King
Decking is one of the largest applications for the treated wood market. The most challenging property to obtain for treated wood is dimensional stability, which can be achieved, in part, by cell wall bulking, cell wall polymer crosslinking and removal of hygroscopic components in the cell wall. A commonly accepted key requirement is for the actives to infuse through the cell wall, which has a microporosity of ∼5-13 nm. Equally as challenging is being able to measure and quantify the cell wall penetration...
November 8, 2017: Journal of Microscopy
I Ipatova, P T Wady, S M Shubeita, C Barcellini, A Impagnatiello, E Jimenez-Melero
The formation of radiation-induced dislocation loops and voids in tantalum at 180(2), 345(3) and 590(5)°C was assessed by 3MeV proton irradiation experiments and subsequent damage characterisation using transmission electron microscopy. Voids formed at 345(3)°C and were arranged into a body centred cubic lattice at a damage level of 0.55 dpa. The low vacancy mobility at 180(2)°C impedes enough vacancy clustering and therefore the formation of voids visible by TEM. At 590(5)°C the Burgers vector of the interstitial-type dislocation loops is a<100>, instead of the a/2 <111> Burgers vector characteristic of the loops at 180(2) and 345(3)°C...
November 1, 2017: Journal of Microscopy
A A Sheader, A M Varambhia, R A Fleck, S J L Flatters, P D Nellist
The chemotherapeutics cisplatin and oxaliplatin are important tools in the fight against cancer. Both compounds are platinum complexes. Aberration-corrected scanning transmission electron microscopy using the annular dark-field imaging mode now routinely provides single-atom sensitivity with atomic number contrast. Here, this imaging mode is used to directly image the platinum within the two drugs in their dried form on an amorphous carbon support film. The oxaliplatin is found to have wetted the supporting amorphous carbon, forming disordered clusters suggesting that the platinum has remained within the complex...
November 1, 2017: Journal of Microscopy
D Westhoff, D P Finegan, P R Shearing, V Schmidt
We describe a segmentation algorithm that is able to identify defects (cracks, holes and breakages) in particle systems. This information is used to segment image data into individual particles, where each particle and its defects are identified accordingly. We apply the method to particle systems that appear in Li-ion battery electrodes. First, the algorithm is validated using simulated data from a stochastic 3D microstructure model, where we have full information about defects. This allows us to quantify the accuracy of the segmentation result...
October 26, 2017: Journal of Microscopy
J Kuva, J Sammaljärvi, J Parkkonen, M Siitari-Kauppi, M Lehtonen, T Turpeinen, J Timonen, M Voutilainen
We set out to study connected porosity of crystalline rock using X-ray microtomography and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) with caesium chloride as a contrast agent. Caesium is an important radionuclide regarding the final deposition of nuclear waste and also forms dense phases that can be readily distinguished by X-ray microtomography and SEM-EDS. Six samples from two sites, Olkiluoto (Finland) and Grimsel (Switzerland), where transport properties of crystalline rock are being studied in situ, were investigated using X-ray microtomography and SEM-EDS...
October 26, 2017: Journal of Microscopy
K Dembele, S Moldovan, Ch Hirlimann, J Harmel, K Soulantica, P Serp, B Chaudret, A-S Gay, S Maury, A Berliet, A Fecant, O Ersen
In situ transmission electron microscopy (TEM) of samples in a controlled gas environment allows for the real time study of the dynamical changes in nanomaterials at high temperatures and pressures up to the ambient pressure (10(5) Pa) with a spatial resolution close to the atomic scale. In the field of catalysis, the implementation and quantitative use of in situ procedures are fundamental for a better understanding of the behaviour of catalysts in their environments and operating conditions. By using a microelectromechanical systems (MEMS)-based atmospheric gas cell, we have studied the thermal stability and the reactivity of crystalline cobalt nanostructures with initial 'urchin-like' morphologies sustained by native surface ligands that result from their synthesis reaction...
October 24, 2017: Journal of Microscopy
B R Gordon, D E Martin, K R Bambery, C A Motti
The symbiotic relationship between corals and Symbiodinium spp. is the key to the success and survival of coral reef ecosystems the world over. Nutrient exchange and chemical communication between the two partners provides the foundation of this key relationship, yet we are far from a complete understanding of these processes. This is due, in part, to the difficulties associated with studying an intracellular symbiosis at the small spatial scales required to elucidate metabolic interactions between the two partners...
October 24, 2017: Journal of Microscopy
Dev Kumar DAS, Asok Kumar Maiti, Chandan Chakraborty
In this paper, we have presented a new computer-aided technique for automatic detection of nucleated red blood cells (NRBCs) or normoblast cell from peripheral blood smear image. The proposed methodology initiates with the localization of the nucleated cells by adopting multilevel thresholding approach in smear images. A novel colour space transformation technique has been introduced to differentiate nucleated blood cells [white blood cells (WBCs) and NRBC] from red blood cells (RBCs) by enhancing the contrast between them...
October 17, 2017: Journal of Microscopy
Anqi Wang, Ian P Jones, Gabriel Landini, Junfa Mei, Yau Y Tse, Yue X Li, Linnan Ke, Yuanli Huang, L I Liu, Chunren Wang, Rachel L Sammons
The application of secondary electron (SE) imaging, backscattered electron imaging (BSE) and electron backscattered diffraction (EBSD) was investigated in this work to study the bacterial adhesion and proliferation on a commercially pure titanium (cp Ti) and a Ti6Al4V alloy (Ti 64) with respect to substrate microstructure and chemical composition. Adherence of Gram-positive Staphylococcus epidermidis 11047 and Streptococcus sanguinis GW2, and Gram-negative Serratia sp. NCIMB 40259 and Escherichia coli 10418 was compared on cp Ti, Ti 64, pure aluminium (Al) and vanadium (V)...
October 11, 2017: Journal of Microscopy
N Chery, T H Ngo, M P Chauvat, B Damilano, A Courville, P DE Mierry, T Grieb, T Mehrtens, F F Krause, K Müller-Caspary, M Schowalter, B Gil, A Rosenauer, P Ruterana
In this work, we analyse the microstructure and local chemical composition of green-emitting Inx Ga1-x N/GaN quantum well (QW) heterostructures in correlation with their emission properties. Two samples of high structural quality grown by metalorganic vapour phase epitaxy (MOVPE) with a nominal composition of x = 0.15 and 0.18 indium are discussed. The local indium composition is quantitatively evaluated by comparing scanning transmission electron microscopy (STEM) images to simulations and the local indium concentration is extracted from intensity measurements...
October 11, 2017: Journal of Microscopy
Ghasem Azimi-Roeen, Seyed Farshid Kashani-Bozorg, Martin Nosko, Lubomir Orovcik
The application of ball-milling for reactant powders (Fe2 O3 +Al) to form in situ nanosized reaction products in the stir zone of 1050 aluminium alloy was examined and the evolution of microstructure, grain boundaries and microtexture of the fabricated Al/(Al13 Fe4 +Al2 O3 ) nanocomposite was investigated. The mean matrix grain size of the fabricated nanocomposites by the combination of ball milling and friction stir processing were found to be ∼3.2, 3.1 and 2.1 μm for 1, 2 and 3 h milled powder mixtures, respectively...
October 9, 2017: Journal of Microscopy
H Ben Ammar, A Minj, M Pierre-Chauvat, P Gamarra, C Lacam, M Morales, P Ruterana
Defects in quaternary InAlGaN barriers and their effects on crystalline quality and surface morphology have been studied. In addition to growth conditions, the quality of the GaN template may play an important role in the formation of defects in the barrier. Therefore, this work is focused on effects caused by threading dislocations (TDs) and inversion domains (IDs) originating from the underlying GaN. The effects are observed on the crystalline quality of the barrier and characteristic surface morphologies...
October 8, 2017: Journal of Microscopy
D J Norris, M Myronov, D R Leadley, T Walther
We compare transmission electron microscopical analyses of the onset of islanding in the germanium-on-silicon (Ge/Si) system for three different Si substrate orientations: (001), (11¯0) and (11¯1)Si. The Ge was deposited by reduced pressure chemical vapour deposition and forms islands on the surface of all Si wafers; however, the morphology (aspect ratio) of the deposited islands is different for each type of wafer. Moreover, the mechanism for strain relaxation is different for each type of wafer owing to the different orientation of the (111) slip planes with the growth surface...
October 3, 2017: Journal of Microscopy
O Y Rogov, V V Artemov, M V Gorkunov, A A Ezhov, D N Khmelenin
Technologies capable of fabricating complex shaped silicon metasurfaces attract increasing attention. The focused ion beam fabrication technique is considered traditionally as causing thick damaged layers in silicon resulting in a significant rise of the optical absorption loss. We examine the structure of the FIB-fabricated nanostructures on the silicon-on-sapphire (SOS) platform and its optical characteristics before and after thermal oxidation. We show that being thermally oxidised the FIB-patterned silicon subwavelength nanostructure tends to regain its chiral optical features...
October 3, 2017: Journal of Microscopy
T Walther, A B Krysa
Quantum cascade lasers can be efficient infrared radiation sources and consist of several hundreds of very thin layers arranged in stacks that are repeated periodically. Both the thicknesses of the individual layers as well as the period lengths need to be monitored to high precision. Different transmission electron microscopy methods have been combined to analyse AlGaAs/GaAs quantum cascade laser structures in cross-section. We found a small parabolic variation of the growth rate during deposition, affecting the stack periodicity and a reduced aluminium content of the AlGaAs barriers, whereas their widths as well as those of the GaAs quantum wells agreed with the nominal values within one atomic layer...
October 3, 2017: Journal of Microscopy
A Cheng, H Chen, Z Schwartz, B D Boyan
Previous work using focused ion beam (FIB) analysis of osteoblasts on smooth and microrough Ti surfaces showed that the average cell aspect ratio and distance from the surface are greater on the rough surface. In order to better interrogate the relationship between individual cells and their substrate using multiple imaging modalities, we developed a method that tracks the same cell across confocal laser scanning microscopy (CLSM) to correlate surface microroughness with cell morphology and cytoskeleton; scanning electron microscopy (SEM) to provide higher resolution for observation of nanoroughness as well as chemical mapping via energy dispersive X-ray spectroscopy; and transmission electron microscopy (TEM) for high-resolution imaging...
September 28, 2017: Journal of Microscopy
A Nalin Mehta, H Zhang, A Dabral, O Richard, P Favia, H Bender, A Delabie, M Caymax, M Houssa, G Pourtois, W Vandervorst
The crystal and defect structure of SnS crystals grown using chemical vapour deposition for application in electronic devices are investigated. The structural analysis shows the presence of two distinct crystal morphologies, that is thin flakes with lateral sizes up to 50 μm and nanometer scale thickness, and much thicker but smaller crystallites. Both show similar Raman response associated with SnS. The structural analysis with transmission electron microscopy shows that the flakes are single crystals of α-SnS with [010] normal to the substrate...
September 28, 2017: Journal of Microscopy
X Wang, M-P Chauvat, P Ruterana, T Walther
We have applied our previous method of self-consistent k*-factors for absorption correction in energy-dispersive X-ray spectroscopy to quantify the indium content in X-ray maps of thick compound InGaN layers. The method allows us to quantify the indium concentration without measuring the sample thickness, density or beam current, and works even if there is a drastic local thickness change due to sample roughness or preferential thinning. The method is shown to select, point-by-point in a two-dimensional spectrum image or map, the k*-factor from the local Ga K/L intensity ratio that is most appropriate for the corresponding sample geometry, demonstrating it is not the sample thickness measured along the electron beam direction but the optical path length the X-rays have to travel through the sample that is relevant for the absorption correction...
September 28, 2017: Journal of Microscopy
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