A Cut above the Rest: Characterization of the Assembly of a Large Viral Icosahedral Capsid

The head of Salmonella virus SPN3US is composed of ~50 different proteins and is unusual because within its packaged genome there is a mass (>40 MDa) of ejection or E proteins that enter the Salmonella cell. The assembly mechanisms of this complex structure are poorly understood. Previous studies showed that eight proteins in the mature SPN3US head had been cleaved by the prohead protease. In this study, we present the characterization of SPN3US prohead protease mutants using transmission electron microscopy and mass spectrometry. In the absence of the prohead protease, SPN3US head formation was severely impeded and proheads accumulated on the Salmonella inner membrane. This impediment is indicative of proteolysis being necessary for the release and subsequent DNA packaging of proheads in the wild-type phage. Proteomic analyses of gp245- proheads that the normal proteolytic processing of head proteins had not occurred. Assays of a recombinant, truncated form of the protease found it was active, leading us to hypothesize that the C-terminal propeptide has a role in targeting the protease into the prohead core. Our findings provide new evidence regarding the essential role of proteolysis for correct head assembly in this remarkable parasite.

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TEM and XRD Investigation of MnO2 Microstructure and its Influence on ESR of Ta Capacitors

Materials Science Forum ◽

10.4028/www.scientific.net/msf.514-516.269 ◽

2006 ◽

Vol 514-516 ◽

pp. 269-273

Author(s):

Décio Dias ◽

Rui Monteiro ◽

Patrícia Almeida Carvalho ◽

Alberto C. Ferro ◽

Werner Lohwasser

Keyword(s):

Complex Structure ◽

Semiconductor Layer ◽

Equivalent Series Resistance ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Equivalent Circuit Parameters ◽

Diffraction Peaks ◽

Diffraction Patterns

The development of solid electrolytic tantalum capacitors with MnO2 as counter electrode has been carried out in order to decrease the equivalent series resistance (ESR). Capacitor samples produced under different pyrolysis conditions have been characterized in terms of equivalent circuit parameters. The Ta/Ta2O5/MnO2 system has also been characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). X-ray powder diffraction patterns obtained were inconclusive due to the MnO2 complex structure and to the presence of highly intense tantalum peaks that shadow interesting MnO2 diffraction peaks. Electron diffraction TEM results enabled the characterization of the microstructure and furthermore revealed the complex crystalline structure that affects the electrical properties of the semiconductor layer. A relation between the calculated circuit parameters and microstructure of MnO2 is discussed.

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Characterization of Arsenic Implanted Epitaxially Aligned Polysilicon-on-Silicon Films

MRS Proceedings ◽

10.1557/proc-106-279 ◽

1987 ◽

Vol 106 ◽

Cited By ~ 1

Author(s):

J. L. Hoyt ◽

E. F. Crabbé ◽

R. F. W. Pease ◽

J. F. Gibbons

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

High Temperature ◽

High Temperature Annealing ◽

Strong Reduction ◽

Diffusion Front ◽

Transmission Electron ◽

Silicon Interface ◽

New Evidence

ABSTRACTNonuniformities in the polysilicon-to-silicon interface and in the polysilicon structure are expected to produce a nonuniform diffusion front when arsenic is diffused from polysilicon during epitaxial alignment. Using transmission electron microscopy, we find surprisingly uniform arsenic diffusion fronts in the underlying silicon substrate following high temperature annealing. Several explanations of this result are proposed. We also report new evidence of a strong reduction in the time to achieve complete epitaxial transformation of the polysilicon when the polysilicon thickness is reduced. A corresponding reduction in the associated arsenic penetration depth is demonstrated.

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The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071107 ◽

1973 ◽

Vol 31 ◽

pp. 132-133 ◽

Cited By ~ 1

Author(s):

R. E. Herfert

Keyword(s):

Surface Characterization ◽

Analytical Techniques ◽

X Ray Diffraction ◽

Depth Of Penetration ◽

X Ray ◽

The Past ◽

Transmission Electron ◽

Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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An Electron Microscope Study of Interdiffusion and Compound Formation in Ta-Au Thin Films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100070606 ◽

1973 ◽

Vol 31 ◽

pp. 32-33 ◽

Cited By ~ 1

Author(s):

T. C. Tisone ◽

S. Lau

Keyword(s):

Electron Microscope ◽

Electron Microscope Study ◽

Thermally Grown Oxide ◽

Ion Milling ◽

Compound Formation ◽

Technology Application ◽

Transmission Electron ◽

Before And After ◽

Au Thin Films

In a study of the properties of a Ta-Au metallization system for thin film technology application, the interdiffusion between Ta(bcc)-Au, βTa-Au and Ta2M-Au films was studied. Considered here is a discussion of the use of the transmission electron microscope(TEM) in the identification of phases formed and characterization of the film microstructures before and after annealing.The films were deposited by sputtering onto silicon wafers with 5000 Å of thermally grown oxide. The film thicknesses were 2000 Å of Ta and 2000 Å of Au. Samples for TEM observation were prepared by ultrasonically cutting 3mm disks from the wafers. The disks were first chemically etched from the silicon side using a HNO3 :HF(19:5) solution followed by ion milling to perforation of the Au side.

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Characterization of RF Sputtered ZnO Piezoelectric Films Using Transmission Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100114050 ◽

1975 ◽

Vol 33 ◽

pp. 86-87

Author(s):

Kemining W. Yeh ◽

Richard S. Muller ◽

Wei-Kuo Wu ◽

Jack Washburn

Keyword(s):

Integrated Circuit ◽

Acoustic Waves ◽

New Technology ◽

Surface Acoustic Waves ◽

Electromechanical Properties ◽

Leading Role ◽

Saw Devices ◽

Transmission Electron ◽

High Degree

Considerable and continuing interest has been shown in the thin film transducer fabrication for surface acoustic waves (SAW) in the past few years. Due to the high degree of miniaturization, compatibility with silicon integrated circuit technology, simplicity and ease of design, this new technology has played an important role in the design of new devices for communications and signal processing. Among the commonly used piezoelectric thin films, ZnO generally yields superior electromechanical properties and is expected to play a leading role in the development of SAW devices.

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Cryomicroscopy of multiphase latices

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100089615 ◽

1991 ◽

Vol 49 ◽

pp. 1060-1061

Author(s):

O. L. Shaffer ◽

M.S. El-Aasser ◽

C. L. Zhao ◽

M. A. Winnik ◽

R. R. Shivers

Keyword(s):

Electron Microscopy ◽

Radiation Damage ◽

Freeze Fracture ◽

Particle Morphology ◽

Second Stage ◽

Transmission Electron ◽

Important Approach ◽

Carbon Coated ◽

Preparation Techniques

Transmission electron microscopy is an important approach to the characterization of the morphology of multiphase latices. Various sample preparation techniques have been applied to multiphase latices such as OsO4, RuO4 and CsOH stains to distinguish the polymer phases or domains. Radiation damage by an electron beam of latices imbedded in ice has also been used as a technique to study particle morphology. Further studies have been developed in the use of freeze-fracture and the effect of differential radiation damage at liquid nitrogen temperatures of the latex particles embedded in ice and not embedded.Two different series of two-stage latices were prepared with (1) a poly(methyl methacrylate) (PMMA) seed and poly(styrene) (PS) second stage; (2) a PS seed and PMMA second stage. Both series have varying amounts of second-stage monomer which was added to the seed latex semicontinuously. A drop of diluted latex was placed on a 200-mesh Formvar-carbon coated copper grid.

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Applications of Transmission Electron Microscopy in the Characterization of Metal Machinability

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101967 ◽

1968 ◽

Vol 26 ◽

pp. 442-443 ◽

Cited By ~ 1

Author(s):

L.E. Murr ◽

A.B. Draper

Keyword(s):

Electron Microscopy ◽

State Physics ◽

Test Material ◽

Milling Machine ◽

Rotary Table ◽

Solid State Physics ◽

Materials Properties ◽

Transmission Electron ◽

Selection Of

The industrial characterization of the machinability of metals and alloys has always been a very arbitrarily defined property, subject to the selection of various reference or test materials; and the adoption of rather naive and misleading interpretations and standards. However, it seems reasonable to assume that with the present state of knowledge of materials properties, and the current theories of solid state physics, more basic guidelines for machinability characterization might be established on the basis of the residual machined microstructures. This approach was originally pursued by Draper; and our presentation here will simply reflect an exposition and extension of this research.The technique consists initially in the production of machined chips of a desired test material on a horizontal milling machine with the workpiece (specimen) mounted on a rotary table vice. A single cut of a specified depth is taken from the workpiece (0.25 in. wide) each at a new tool location.

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Comparison of Ion-Milling Techniques For Cross-Sectional TEM of Semiconductors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117807 ◽

1985 ◽

Vol 43 ◽

pp. 166-167

Author(s):

Julia T. Luck ◽

C. W. Boggs ◽

S. J. Pennycook

Keyword(s):

Analytical Techniques ◽

Sample Surface ◽

Ion Milling ◽

Cross Sectional ◽

Reliable Technique ◽

Near Surface ◽

Transmission Electron ◽

Thin Region ◽

Transient Thermal

The use of cross-sectional Transmission Electron Microscopy (TEM) has become invaluable for the characterization of the near-surface regions of semiconductors following ion-implantation and/or transient thermal processing. A fast and reliable technique is required which produces a large thin region while preserving the original sample surface. New analytical techniques, particularly the direct imaging of dopant distributions, also require good thickness uniformity. Two methods of ion milling are commonly used, and are compared below. The older method involves milling with a single gun from each side in turn, whereas a newer method uses two guns to mill from both sides simultaneously.

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convergent-beam diffraction from surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100125208 ◽

1987 ◽

Vol 45 ◽

pp. 30-33

Author(s):

J. A. Eades ◽

A. E. Smith ◽

D. F. Lynch

Keyword(s):

Reciprocal Lattice ◽

Three Dimensional ◽

Grazing Incidence ◽

Three Dimensions ◽

Plane Figure ◽

Transmission Electron ◽

Convergent Beam ◽

Beam Patterns ◽

Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

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Interface structures in polycrystalline ceramic materials

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143900 ◽

1986 ◽

Vol 44 ◽

pp. 468-471

Author(s):

K. J. Morrissey

Keyword(s):

Electron Microscopy ◽

Analytical Electron Microscopy ◽

Physical And Mechanical Properties ◽

High Resolution Electron Microscopy ◽

Ceramic Materials ◽

Polycrystalline Materials ◽

Transmission Electron ◽

Resolution Electron ◽

Interface Structures

Grain boundaries and interfaces play an important role in determining both physical and mechanical properties of polycrystalline materials. To understand how the structure of interfaces can be controlled to optimize properties, it is necessary to understand and be able to predict their crystal chemistry. Transmission electron microscopy (TEM), analytical electron microscopy (AEM,), and high resolution electron microscopy (HREM) are essential tools for the characterization of the different types of interfaces which exist in ceramic systems. The purpose of this paper is to illustrate some specific areas in which understanding interface structure is important. Interfaces in sintered bodies, materials produced through phase transformation and electronic packaging are discussed.

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