Possibilities of Controlling the Dynamic Properties of a Cylindrical Piezoceramic Acousto-electronic Device with Two-frequency Resonance Excitation

An electronic device has been constructed which manipulates the primary beam in the conventional transmission microscope to illuminate a specimen under a variety of virtual condenser aperture conditions. The device uses the existing tilt coils of the microscope, and modulates the D.C. signals to both x and y tilt directions simultaneously with various waveforms to produce Lissajous figures in the back-focal plane of the objective lens. Electron diffraction patterns can be recorded which reflect the manner in which the direct beam is tilted during exposure of a micrograph. The device has been utilized mainly for the hollow cone imaging mode where the device provides a microscope transfer function without zeros in all spatial directions and has produced high resolution images which are also free from the effect of chromatic aberration. A standard second condenser aperture is employed and the width of the cone annulus is readily controlled by defocusing the second condenser lens.

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Resistance Monitor and Control for Vacuum Evaporation of Metals and Carbon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092827 ◽

1976 ◽

Vol 34 ◽

pp. 572-573

Author(s):

Russell L. Steere ◽

Eric F. Erbe ◽

J. Michael Moseley

Keyword(s):

Electronic Device ◽

Point Sources ◽

High Contrast ◽

Variable Resistor ◽

Quality Of Results ◽

Low Contrast ◽

Evaporation Source ◽

And Control ◽

At Will

We have designed and built an electronic device which compares the resistance of a defined area of vacuum evaporated material with a variable resistor. When the two resistances are matched, the device automatically disconnects the primary side of the substrate transformer and stops further evaporation.This approach to controlled evaporation in conjunction with the modified guns and evaporation source permits reliably reproducible multiple Pt shadow films from a single Pt wrapped carbon point source. The reproducibility from consecutive C point sources is also reliable. Furthermore, the device we have developed permits us to select a predetermined resistance so that low contrast high-resolution shadows, heavy high contrast shadows, or any grade in between can be selected at will. The reproducibility and quality of results are demonstrated in Figures 1-4 which represent evaporations at various settings of the variable resistor.

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Digital image processing methods applied to the study of annealing time on semiconductor-metal eutectic composites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106302 ◽

1988 ◽

Vol 46 ◽

pp. 848-849

Author(s):

J. Hefter

Keyword(s):

Image Processing ◽

Digital Image Processing ◽

Digital Image ◽

Electronic Device ◽

Processing System ◽

Average Diameter ◽

Eutectic Solidification ◽

Metal Silicide ◽

The Matrix ◽

Microscopic Studies

Semiconductor-metal composites, formed by the eutectic solidification of silicon and a metal silicide have been under investigation for some time for a number of electronic device applications. This composite system is comprised of a silicon matrix containing extended metal-silicide rod-shaped structures aligned in parallel throughout the material. The average diameter of such a rod in a typical system is about 1 μm. Thus, characterization of the rod morphology by electron microscope methods is necessitated.The types of morphometric information that may be obtained from such microscopic studies coupled with image processing are (i) the area fraction of rods in the matrix, (ii) the average rod diameter, (iii) an average circularity (roundness), and (iv) the number density (Nd;rods/cm2). To acquire electron images of these materials, a digital image processing system (Tracor Northern 5500/5600) attached to a JEOL JXA-840 analytical SEM has been used.

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The distribution of antigen on the surface of RBL-2H3 rat basophilic leukemia cells observed by back-scattered electron imaging

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100142992 ◽

1986 ◽

Vol 44 ◽

pp. 274-275

Author(s):

R.F. Stump ◽

J.R. Pfeiffer ◽

JC. Seagrave ◽

D. Huskisson ◽

J.M. Oliver

Keyword(s):

Cell Surface ◽

Dynamic Properties ◽

Leukemia Cells ◽

Antigen Binding ◽

Scattered Electron ◽

Ige Receptor ◽

Receptor Complexes ◽

Rat Basophilic Leukemia Cells ◽

Electron Imaging ◽

Basophilic Leukemia

In RBL-2H3 rat basophilic leukemia cells, antigen binding to cell surface IgE-receptor complexes stimulates the release of inflammatory mediators and initiates a series of membrane and cytoskeletal events including a transformation of the cell surface from a microvillous to a lamellar topography. It is likely that dynamic properties of the IgE receptor contribute to the activation of these responses. Fewtrell and Metzger have established that limited crosslinking of IgE-receptor complexes is essential to trigger secretion. In addition, Baird and colleagues have reported that antigen binding causes a rapid immobilization of IgE-receptor complexes, and we have demonstrated an apparent increase with time in the affinity of IgE-receptor complexes for antigen.

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In situ TEM measurements of the electrical properties of interface dislocations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131322 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1338-1339

Author(s):

F. M. Ross ◽

R. Hull ◽

D. Bahnck ◽

J. C. Bean ◽

L. J. Peticolas ◽

...

Keyword(s):

Electrical Properties ◽

Electronic Device ◽

In Situ Tem ◽

Device Performance ◽

Misfit Dislocations ◽

Electrical Characteristics ◽

Strained Layer ◽

Transmission Electron ◽

Interfacial Dislocations

We describe an investigation of the electrical properties of interfacial dislocations in strained layer heterostructures. We have been measuring both the structural and electrical characteristics of strained layer p-n junction diodes simultaneously in a transmission electron microscope, enabling us to correlate changes in the electrical characteristics of a device with the formation of dislocations.The presence of dislocations within an electronic device is known to degrade the device performance. This degradation is of increasing significance in the design and processing of novel strained layer devices which may require layer thicknesses above the critical thickness (hc), where it is energetically favourable for the layers to relax by the formation of misfit dislocations at the strained interfaces. In order to quantify how device performance is affected when relaxation occurs we have therefore been investigating the electrical properties of dislocations at the p-n junction in Si/GeSi diodes.

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Nucleosome dynamics

Biochemical Society Symposium ◽

10.1042/bss0730109 ◽

2006 ◽

Vol 73 ◽

pp. 109-119 ◽

Cited By ~ 2

Author(s):

Chris Stockdale ◽

Michael Bruno ◽

Helder Ferreira ◽

Elisa Garcia-Wilson ◽

Nicola Wiechens ◽

...

Keyword(s):

High Resolution ◽

Chromatin Structure ◽

Current Knowledge ◽

Dynamic Properties ◽

Structure And Dynamics ◽

Nucleosome Dynamics ◽

Sharp Focus ◽

Recent Advances ◽

Insight Into ◽

Chromatin Structure And Dynamics

In the 30 years since the discovery of the nucleosome, our picture of it has come into sharp focus. The recent high-resolution structures have provided a wealth of insight into the function of the nucleosome, but they are inherently static. Our current knowledge of how nucleosomes can be reconfigured dynamically is at a much earlier stage. Here, recent advances in the understanding of chromatin structure and dynamics are highlighted. The ways in which different modes of nucleosome reconfiguration are likely to influence each other are discussed, and some of the factors likely to regulate the dynamic properties of nucleosomes are considered.

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