Microstructural investigation of the Carancas meteorite

2010 ◽  
Vol 10 (2) ◽  
pp. 105-112 ◽  
Author(s):  
Kani Rauf ◽  
Anthony Hann ◽  
Chandra Wickramasinghe ◽  
Barry E. DiGregorio
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Intermediate Zone ◽  
Hydroxyl Groups ◽  
X Rays ◽  
Microstructural Investigation ◽  
Dark Zone ◽  
Transmission Electron ◽  
Scanning Electron

AbstractParticles in the Carancas meteorite were examined by electron microscopy (transmission electron microscopy/scanning electron microscopy), energy dispersive analysis of X-rays (EDAX) and Fourier Transform Infrared spectroscopy. Scanning electron microscopical observations reveal that the particles of variable sizes have a stony appearance. Many of these particles show fractures in places, thus confirming an ealier observation that the meteorite was subjected to a high-velocity impact. The outer rim of many aggregates displays a mud crack-like texture. At high magifications, this texture shows ovoid and elongated features, which appear similar to microfossils found in other meteorites.As revealed by both scanning and transmission electron microscopy, some particles show three clearly marked zones, distinguishable by their differences in electron density and texture: a light zone, a dark zone and an intermediate zone. The EDAX analysis of these particles shows that the light zone is composed of silicates rich in Fe, Ni and S (the elements of troilite and pentlandite). The dark zone contains high concentrations of Mg and Si (the major elements of high-temperature minerals, such as forsterite, Mg2SiO4 and enstatite, MgSiO3) intermixed with carbonates and traces of Al, Ca and Na. The intermediate zone also contains high-temperature minerals and Fe-Ni rich silicates.The Carancas meteorite produces an infrared waveband showing prominent features of some carbonate species, amorphous and crystalline silicates, and olivine groups. Hydrated silicates and hydroxyl groups are less abundant, as shown by the presence of small humps between 2.5 and 8.0 μm.The abundance of high-temperature minerals and iron-rich metal confirms an earlier observation that the meteorite is an ordinary H4/5 chondrite. Some particles in the Carancas meteorite are found to have structural and chemical characteristics similar to those of the 81P/Wild 2 comet.

scholarly journals Intracytoplasmic Crystalline Inclusions in the Hepatocytes of an Antelope

2010 ◽  
Vol 2010 ◽  
pp. 1-4
Author(s):  
Sanjeev Gumber ◽  
Eric Lombardini ◽  
Bruce Williams ◽  
Nobuko Wakamatsu
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Homogeneous Material ◽  
X Rays ◽  
Crystalline Inclusions ◽  
Cytoplasmic Vacuoles ◽  
Transmission Electron ◽  
Calcium And Phosphorus ◽  
Scanning Electron

This case report describes intracytoplasmic crystalline inclusions in the hepatocytes of a 13-year-old female Thomson's gazelle. Histologically, multifocal to coalescing areas of many hepatocytes contained large cytoplasmic vacuoles filled with pale eosinophilic homogeneous material and rare fine basophilic granules. Von Kossa staining showed the presence of calcium within cytoplasm, mainly in the inclusions, of hepatocytes. Transmission electron microscopy, scanning electron microscopy, energy dispersive X-rays analyses, and infrared spectroscopy on the liver showed the hepatocellular material consistent with protein and carbohydrate with secondary accumulation of calcium and phosphorus. It was concluded that crystalline inclusions may have been derived due to failure of normal physiological hepatocellular clearance associated with a severe chronic disease. To the authors' knowledge this is the first reported case of hepatocellular crystalline inclusions in an antelope.

Study on High Temperature Properties of CuCrAg Alloy

2018 ◽  
Vol 921 ◽  
pp. 141-146
Author(s):  
Zong Wu Li ◽  
Hao Feng Xie ◽  
Guo Jie Huang ◽  
Xue Feng ◽  
Li Jun Peng ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Fracture Morphology ◽  
Nominal Composition ◽  
High Temperature Properties ◽  
Transmission Electron ◽  
Creep Curves ◽  
Scanning Electron

In this paper, nominal composition of Cu-0.3Cr-0.07Ag (at%) was designed. The high temperature properties and microstructure were investigated by Transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results show that the tensile strength of CuCrAg decreases as temperature rises, which was associated with the coarsen precipitates according to TEM observation. Furthermore, observations of fracture morphology reveal that the mechanism transforms into brittle fracture from ductile fracture at elevated temperature. Creep curves were found to vary as a function of applied stress and temperature, the stress exponent values are 8.7, 4.6, 4.3 at 673K, 773K, 873K respectively. The mechanism is dislocation climbing at 773K and 873K while creep behavior at 673K could be explained by the invariant substructure model.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

Scanning and Transmission Electron Microscopy of Human Red Blood Cells

1969 ◽  
Vol 27 ◽  
pp. 44-45
Author(s):  
A.J. Tousimis ◽  
T.R. Padden
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Blood Cells ◽  
Room Temperature ◽  
Type Specimen ◽  
New Combination ◽  
Human Red Blood Cells ◽  
Transmission Electron ◽  
Microscope Slides ◽  
Scanning Electron

The size, shape and surface morphology of human erythrocytes (RBC) were examined by scanning electron microscopy (SEM), of the fixed material directly and by transmission electron microscopy (TEM) of surface replicas to compare the relative merits of these two observational procedures for this type specimen.A sample of human blood was fixed in glutaraldehyde and washed in distilled water by centrifugation. The washed RBC's were spread on freshly cleaved mica and on aluminum coated microscope slides and then air dried at room temperature. The SEM specimens were rotary coated with 150Å of 60:40- gold:palladium alloy in a vacuum evaporator using a new combination spinning and tilting device. The TEM specimens were preshadowed with platinum and then rotary coated with carbon in the same device. After stripping the RBC-Pt-C composite film, the RBC's were dissolved in 2.5N HNO3 followed by 0.2N NaOH leaving the preshadowed surface replicas showing positive topography.

Comparative Study of the Fine Morphology of Sensory Receptors in Aspidogaster conchicola and Cotylaspis insignis

1972 ◽  
Vol 30 ◽  
pp. 150-151
Author(s):  
Venita F. Allison ◽  
J. E. Ubelaker ◽  
J. H. Martin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Nervous System ◽  
Osmic Acid ◽  
Sensory Receptors ◽  
Transmission Electron ◽  
Sensory Structures ◽  
Fine Morphology ◽  
Scanning Electron

It has been suggested that parasitism results in a reduction of sensory structures which concomitantly reflects a reduction in the complexity of the nervous system. The present study tests this hypothesis by examining the fine morphology and the distribution of sensory receptors for two species of aspidogastrid trematodes by transmission and scanning electron microscopy. The species chosen are an ectoparasite, Cotylaspis insignis and an endoparasite, Aspidogaster conchicola.Aspidogaster conchicola and Cotylaspis insignis were obtained from natural infections of clams, Anodonta corpulenta and Proptera purpurata. The specimens were fixed for transmission electron microscopy in phosphate buffered paraformaldehyde followed by osmic acid in the same buffer, dehydrated in an ascending series of ethanol solutions and embedded in Epon 812.

Anisotropic Membranes as Substrates for Sem

1976 ◽  
Vol 34 ◽  
pp. 444-445
Author(s):  
Thomas P. Turnbull ◽  
W. F. Bowers
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Flow ◽  
Polymer Chemistry ◽  
Surface Porosity ◽  
Transmission Electron ◽  
Pore Texture ◽  
Spongy Layer ◽  
Scanning Electron

Until recently the prime purposes of filters have been to produce clear filtrates or to collect particles from solution and then remove the filter medium and examine the particles by transmission electron microscopy. These filters have not had the best characteristics for scanning electron microscopy due to the size of the pores or the surface topography. Advances in polymer chemistry and membrane technology resulted in membranes whose characteristics make them versatile substrates for many scanning electron microscope applications. These polysulphone type membranes are anisotropic, consisting of a very thin (0.1 to 1.5 μm) dense skin of extremely fine, controlled pore texture upon a much thicker (50 to 250μm), spongy layer of the same polymer. Apparent pore diameters can be controlled in the range of 10 to 40 A. The high flow ultrafilters which we are describing have a surface porosity in the range of 15 to 25 angstrom units (0.0015-0.0025μm).

Digital imaging: When should one take the plunge?

1996 ◽  
Vol 54 ◽  
pp. 602-603
Author(s):  
John F. Mansfield
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Optical Microscopy ◽  
Digital Imaging ◽  
Storage Devices ◽  
Major Benefit ◽  
Transmission Electron ◽  
New Instrument ◽  
Scanning Electron

The current imaging trend in optical microscopy, scanning electron microscopy (SEM) or transmission electron microscopy (TEM) is to record all data digitally. Most manufacturers currently market digital acquisition systems with their microscope packages. The advantages of digital acquisition include: almost instant viewing of the data as a high-quaity positive image (a major benefit when compared to TEM images recorded onto film, where one must wait until after the microscope session to develop the images); the ability to readily quantify features in the images and measure intensities; and extremely compact storage (removable 5.25” storage devices which now can hold up to several gigabytes of data).The problem for many researchers, however, is that they have perfectly serviceable microscopes that they routinely use that have no digital imaging capabilities with little hope of purchasing a new instrument.

scholarly journals The Domain and Microstructure of Resin-Bonded Magnets

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2849
Author(s):  
Marcin Jan Dośpiał
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Size Distribution ◽  
Domain Structure ◽  
Grain Size Distribution ◽  
Exchange Interactions ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Scanning Electron

This paper presents domain and structure studies of bonded magnets made from nanocrystalline Nd-(Fe, Co)-B powder. The structure studies were investigated using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Mössbauer spectroscopy and X-ray diffractometry. On the basis of performed qualitative and quantitative phase composition studies, it was found that investigated alloy was mainly composed of Nd2(Fe-Co)14B hard magnetic phase (98 vol%) and a small amount of Nd1.1Fe4B4 paramagnetic phase (2 vol%). The best fit of grain size distribution was achieved for the lognormal function. The mean grain size determined from transmission electron microscopy (TEM) images on the basis of grain size distribution and diffraction pattern using the Bragg equation was about ≈130 nm. HRTEM images showed that over-stoichiometric Nd was mainly distributed on the grain boundaries as a thin amorphous border of 2 nm in width. The domain structure was investigated using a scanning electron microscope and metallographic light microscope, respectively, by Bitter and Kerr methods, and by magnetic force microscopy. Domain structure studies revealed that the observed domain structure had a labyrinth shape, which is typically observed in magnets, where strong exchange interactions between grains are present. The analysis of the domain structure in different states of magnetization revealed the dynamics of the reversal magnetization process.

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