High Voltage Electron Microscope Study Research Articles

High-voltage electron microscope study of the release of vaccinia virus from whole cells.

High-voltage (1,000-kV) electron microscope examination of whole BSC-1 cells infected with vaccinia virus at different times after infection revealed the presence of increasing numbers of virions no longer confined to factories but situated along the cell periphery of monolayer cells. Stereoscopic images showed each virus enclosed within a membrane-like component of the host cell cytoplasm. Viruses within factories appeared to lack similar enclosures. Cytochalasin B, but not vinblastine, caused the enclosures to disrupt. Vaccinia viruses were observed to escape the host cell individually from the tips of microvillie and within packets of cytoplasm. Observations suggest that the intracellular movement and release of vaccinia virus utilize a host cell cytoplasmic network that involves microfilaments for stability.

High Voltage Electron Microscopy Study on the 9R type Bainite in a Ag-26.6wt%Zn Alloy

High Voltage Electron Microscopy Study on the 9R type Bainite in a Ag-26.6wt%Zn Alloy

A high voltage electron microscope study of recrystallization in copper alloys

SUMMARYRecrystallization and recovery have been studied in the high voltage electron microscope (HVEM) in pure copper and two copper‐phosphorus alloys following heavy rolling deformation. Prior to the nucleation of recrystallized grains, extensive subgrain growth occurs by sub‐boundary migration. In the alloys, the first recrystallized grains are observed to nucleate within deformed matrix regions of the same orientation. The orientations of these grains are in close agreement with the crystallographic texture of the metal at complete recrystallization. Growth selection of orientation does not appear to be important. In pure copper, cube‐oriented recrystallized grains form after those of some other orientations, but grow more rapidly and absorb these during growth.

High voltage electron microscope studies of void nucleation in nickel

SUMMARYThe influence of dislocation behaviour on void formation in the high voltage electron microscope (HVEM) has been predicted theoretically and confirmed by experiment. The probability of void nucleation has been computed as a function of the radial distance from a dislocation line in a finite cylinder of material. The observation of strings of voids associated with dislocation lines supports the predictions of the model. Void formation in the HVEM is closely related to the detailed microstructural changes that occur immediately upon electron irradiation, and a good correlation is obtained between the initial interstitial loop density and subsequent swelling by electrons. A minimum foil thickness is necessary for void growth in the HVEM, otherwise the surfaces dominate and the dislocation density always remains low.

Testing of a hypothesis for osmotic opening of the blood-brain barrier.

Testing of a hypothesis for osmotic opening of the blood-brain barrier.

A high voltage electron microscope study of the effects of preinjected helium on electron damage in aluminium

Defect clusters were formed and observed simultaneously in electron irradiated foils of aluminum, both uninjected and preinjected with about 8 atomic ppm helium, in a high voltage electron microscope operated at 650V. The nominal irradiation temperatures of the specimens were room temperature, 150°C and 200°C. The defect clusters in the form of dislocation loops formed in greater concentrations and persisted to longer times in the preinjected specimens than they did in the uninjected metal. At 200°C, no beam-induced loops were observed in the uninjected aluminum foil of usual thickness, but they were seen in the helium injected material. Faulted dislocation loops were more prevalent in the preinjected specimens. Under certain conditions the irradiated microstructure evolved to one resembling an unirradiated structure. It is concluded that the preinjected helium itself (rather than the associated alpha particle damage) causes the enhanced dislocation loop formation in the electron bombarded foils.

Fabric of Kaolinite and Illite Floccules

AbstractA scanning and high voltage electron microscope study of the fabric of laboratory sedimented moist uncompressed kaolinite and illite floccules reveals an abundance of face-face flake orientation in the porous clay network. Clays were flocculated in the laboratory in both distilled water and slightly saline (1 g/l. NaCl) water using various clay concentrations. Floccules taken from the moist clay mass were prepared for study by freeze-drying and impregnation with polyethylene glycol.There is little difference in the fabric of kaolinite flocculated in distilled or slightly saline water. The fabric is dominated by a 3-dimensional network of twisted chains of face-face oriented flakes having the appearance of a stair-stepped cardhouse. Illite floccules in distilled water also consist of abundant face-face oriented overlapping flakes. However, in salt water there is a more even mixture of fabrics—edge-to-face flocculation of individual platelets and also stepped clusters of face-to-face oriented flakes, the latter being more abundant.It is suggested that under the experimental conditions the double layer of each clay particle is compressed resulting in an increase in the importance of van der Waals forces of attraction. As a result flakes approach each other and rotate into a parallel or subparallel position. The resultant dominant fabric is that of a stepped cluster of overlapping flakes.

A High Voltage Electron Microscopy Study of Sub-Oxide Formation in Vanadium

Detailed electron microscope and diffraction studies of the sub-oxides of vanadium have been reported by Cambini and co-workers, and an oxidation study, possibly complicated by carbon and/or nitrogen, has been published by Edington and Smallman. The results reported by these different authors are not in good agreement. For this study, high purity polycrystalline vanadium samples were electrochemically thinned in a dual jet polisher using a solution of 20% H2SO4, 80% CH3OH, and then oxidized in an ion-pumped ultra-high vacuum reactor system using spectroscopically pure oxygen. Samples were oxidized at 350°C and 100μ oxygen pressure for periods of 30,60,90 and 160 minutes. Since our primary interest is in the mechanism of the low pressure oxidation process, the oxidized samples were cooled rapidly and not homogenized. The specimens were then examined in the HVEM at voltages up to 500 kV, the higher voltages being necessary to examine thick sections for which the oxidation behavior was more characteristic of the bulk.

High voltage electron microscope studies of fossil nuclear particle tracks in extraterrestrial matter

Fossil nuclear particle tracks in lunar and meteoritic materials have been searched for with the 1 MeV electron microscope of the Institut d'Optique Electronique du C.N.R.S., Toulouse, both before and after a chemical etching of the samples. Evidences for very high densities of non etchable tracks of two different kinds have been observed only in the finest fraction (<400 mesh) of the lunar soil from the Apollo 11 and 12 missions but not in the type 1 carbonaceous chondrite Orgueil, in the dark part of the solar type gas-rich Pesyanoe enstatite achondrite or in crystals extracted from lunar rock 10047. These track densities can exceed by a factor of 100, the densities of etched tracks measured in the same lunar soil samples. Some implications of the present results concerning lunar and meteoritic matter, the “ancient” fluxes of solar particles and solid state physics are briefly discussed.