Enhancing strength and electrical conductivity of Cu–Cr composite wire by two-stage rotary swaging and aging treatments

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

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Macromolecular structures of biological specimens are not obscured by controlled osmium impregnation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100076639 ◽

1983 ◽

Vol 41 ◽

pp. 606-607

Author(s):

Klaus-Ruediger Peters ◽

Samuel A. Green

Keyword(s):

Thin Films ◽

Electrical Conductivity ◽

Critical Point ◽

Metal Films ◽

High Magnification ◽

Osmium Impregnation ◽

Instrumental Resolution ◽

20 Nm ◽

Continuous Metal

High magnification imaging of macromolecules on metal coated biological specimens is limited only by wet preparation procedures since recently obtained instrumental resolution allows visualization of topographic structures as smal l as 1-2 nm. Details of such dimensions may be visualized if continuous metal films with a thickness of 2 nm or less are applied. Such thin films give sufficient contrast in TEM as well as in SEM (SE-I image mode). The requisite increase in electrical conductivity for SEM of biological specimens is achieved through the use of ligand mediated wet osmiuum impregnation of the specimen before critical point (CP) drying. A commonly used ligand is thiocarbohvdrazide (TCH), first introduced to TEM for en block staining of lipids and glvcomacromolecules with osmium black. Now TCH is also used for SEM. However, after ligand mediated osinification nonspecific osmium black precipitates were often found obscuring surface details with large diffuse aggregates or with dense particular deposits, 2-20 nm in size. Thus, only low magnification work was considered possible after TCH appl ication.

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Two-stage self-seeding method for preparation of single crystals of poly(phenylene sulfide)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153816 ◽

1989 ◽

Vol 47 ◽

pp. 368-369

Author(s):

Sengshiu Chung ◽

Peggy Cebe

Keyword(s):

Single Crystals ◽

High Performance ◽

Dilute Solution ◽

Two Stage ◽

Annealing Behavior ◽

High Performance Polymers ◽

Seeding Method ◽

Phenylene Sulfide

We are studying the crystallization and annealing behavior of high performance polymers, like poly(p-pheny1ene sulfide) PPS, and poly-(etheretherketone), PEEK. Our purpose is to determine whether PPS, which is similar in many ways to PEEK, undergoes reorganization during annealing. In an effort to address the issue of reorganization, we are studying solution grown single crystals of PPS as model materials.Observation of solution grown PPS crystals has been reported. Even from dilute solution, embrionic spherulites and aggregates were formed. We observe that these morphologies result when solutions containing uncrystallized polymer are cooled. To obtain samples of uniform single crystals, we have used two-stage self seeding and solution replacement techniques.

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