Observation of the Stress Distribution in Textile Fabrics Using Thermographic Stress Imaging Method

In studying ion implanted semiconductors and fast neutron irradiated metals, the need for characterizing small dislocation loops having diameters of a few hundred angstrom units usually arises. The weak beam imaging method is a powerful technique for analyzing these loops. Because of the large reduction in stacking fault (SF) fringe spacing at large sg, this method allows for a rapid determination of whether the loop is faulted, and, hence, whether it is a perfect or a Frank partial loop. This method was first used by Bicknell to image small faulted loops in boron implanted silicon. He explained the fringe spacing by kinematical theory, i.e., ≃l/(Sg) in the fault fringe in depth oscillation. The fault image contrast formation mechanism is, however, really more complicated.

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Performance and applications of the holography electron microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100151222 ◽

1993 ◽

Vol 51 ◽

pp. 1078-1079

Author(s):

Akira Tonomura

Keyword(s):

Electron Beam ◽

Electron Microscope ◽

Phase Measurement ◽

Electron Holography ◽

Imaging Method ◽

High Contrast ◽

Magnetic Lens ◽

High Brightness ◽

Holographic Imaging ◽

Dynamic Observation

Electron holography is a two-step imaging method. However, the ultimate performance of holographic imaging is mainly determined by the brightness of the electron beam used in the hologram-formation process. In our 350kV holography electron microscope (see Fig. 1), the decrease in the inherently high brightness of field-emitted electrons is minimized by superposing a magnetic lens in the gun, for a resulting value of 2 × 109 A/cm2 sr. This high brightness has lead to the following distinguished features. The minimum spacing (d) of carrier fringes is d = 0.09 Å, thus allowing a reconstructed image with a resolution, at least in principle, as high as 3d=0.3 Å. The precision in phase measurement can be as high as 2π/100, since the position of fringes can be known precisely from a high-contrast hologram formed under highly collimated illumination. Dynamic observation becomes possible because the current density is high.

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The concerted use of SEM, TEM, and SCM for examination of resin-dentin interfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100170116 ◽

1994 ◽

Vol 52 ◽

pp. 476-477

Author(s):

B. Van Meerbeek ◽

L. J. Conn ◽

E. S. Duke

Keyword(s):

Surface Layer ◽

Stress Distribution ◽

Phosphoric Acid ◽

Bonding Mechanism ◽

Restorative Dentistry ◽

Dental Adhesive ◽

Low Viscosity ◽

Dentin Adhesives ◽

Acid Etch ◽

Tooth Tissue

Restoration of decayed teeth with tooth-colored materials that can be bonded to tooth tissue has been a highly desirable property in restorative dentistry for many years. Advantages of such an adhesive restorative technique over conventional techniques using non-adhesive metal-based restoratives include improved restoration retention with minimal sacrifice of sound tooth tissue for retention purposes, superior adaptation and sealing of the restoration margins in prevention of caries recurrence, improved stress distribution across the tooth-restoration interface throughout the whole tooth, and even reinforcement of weakened tooth structures. The dental adhesive technology is rapidly changing. An efficient resin bond to enamel has already long been achieved. Its bonding mechanism has been fully elucidated and has proven to be a durable and reliable clinical treatment. However, bonding to dentin represents a greater challenge. After the failures of a dentin acid-etch technique in imitation of the enamel phosphoric-acid-etch technique and a bonding procedure based on chemical adhesion, modern dentin adhesives are currently believed to bond to dentin by a micromechanical hybridization process. This process is developed by an initial demineralization of the dentin surface layer with acid etchants exposing a collagen fibril arrangement with interfibrillar microporosities that subsequently become impregnated by low-viscosity monomers. Although the development of such a hybridization process has well been documented in the literature, questions remain with respect to parameters of-primary importance to adhesive efficacy.

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