Laser tomographic reconstruction in a complex concentration flow field

Three-dimensional (3D) microstructure visualization on the electron microscope requires that the sample be tilted to different positions to collect a series of projections. This tilting should be performed rapidly for on-line stereo viewing and precisely for off-line tomographic reconstruction. Usually a projection series is collected using mechanical stage tilt alone. The stereo pairs must be viewed off-line and the 60 to 120 tomographic projections must be aligned with fiduciary markers or digital correlation methods. The delay in viewing stereo pairs and the alignment problems in tomographic reconstruction could be eliminated or improved by tilting the beam if such tilt could be accomplished without image translation.A microscope capable of beam tilt with simultaneous image shift to eliminate tilt-induced translation has been investigated for 3D imaging of thick (1 μm) biologic specimens. By tilting the beam above and through the specimen and bringing it back below the specimen, a brightfield image with a projection angle corresponding to the beam tilt angle can be recorded (Fig. 1a).

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Methods for three-dimensional reconstruction of cellular components within a thick section

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141871 ◽

1986 ◽

Vol 44 ◽

pp. 18-21

Author(s):

J. Frank ◽

B. F. McEwen ◽

M. Radermacher ◽

C. L. Rieder

Keyword(s):

Tilt Angle ◽

Tomographic Reconstruction ◽

3D Structure ◽

Three Dimensional ◽

Thick Section ◽

Three Dimensional Reconstruction ◽

Axis Ratio ◽

Dimensional Reconstruction ◽

Cellular Components

The tomographic reconstruction from multiple projections of cellular components, within a thick section, offers a way of visualizing and quantifying their three-dimensional (3D) structure. However, asymmetric objects require as many views from the widest tilt range as possible; otherwise the reconstruction may be uninterpretable. Even if not for geometric obstructions, the increasing pathway of electrons, as the tilt angle is increased, poses the ultimate upper limitation to the projection range. With the maximum tilt angle being fixed, the only way to improve the faithfulness of the reconstruction is by changing the mode of the tilting from single-axis to conical; a point within the object projected with a tilt angle of 60° and a full 360° azimuthal range is then reconstructed as a slightly elliptic (axis ratio 1.2 : 1) sphere.

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Practical electron tomography

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100140087 ◽

1995 ◽

Vol 53 ◽

pp. 742-743

Author(s):

C.L. Woodcock

Keyword(s):

Electron Tomography ◽

Tomographic Reconstruction ◽

Three Dimensional ◽

3D Shape ◽

Computational Resources ◽

Shape Of Particles

Despite the potential of the technique, electron tomography has yet to be widely used by biologists. This is in part related to the rather daunting list of equipment and expertise that are required. Thanks to continuing advances in theory and instrumentation, tomography is now more feasible for the non-specialist. One barrier that has essentially disappeared is the expense of computational resources. In view of this progress, it is time to give more attention to practical issues that need to be considered when embarking on a tomographic project. The following recommendations and comments are derived from experience gained during two long-term collaborative projects.Tomographic reconstruction results in a three dimensional description of an individual EM specimen, most commonly a section, and is therefore applicable to problems in which ultrastructural details within the thickness of the specimen are obscured in single micrographs. Information that can be recovered using tomography includes the 3D shape of particles, and the arrangement and dispostion of overlapping fibrous and membranous structures.

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Detailed measurements of the flow field in vaneless and vaned diffusers of centrifugal compressors

Journal de Physique III ◽

10.1051/jp3:1992213 ◽

1992 ◽

Vol 2 (9) ◽

pp. 1787-1804 ◽

Cited By ~ 2

Author(s):

Christian Fradin

Keyword(s):

Flow Field ◽

Centrifugal Compressors

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Numerical Study of the Combined Free-Forced Convection and Mass Transfer Flow Past a Vertical Porous Plate in a Porous Medium with Heat Generation and Thermal Diffusion

Nonlinear Analysis Modelling and Control ◽

10.15388/na.2006.11.4.14737 ◽

2006 ◽

Vol 11 (4) ◽

pp. 331-343 ◽

Cited By ~ 19

Author(s):

M. S. Alam ◽

M. M. Rahman ◽

M. A. Samad

Keyword(s):

Mass Transfer ◽

Flow Field ◽

Differential Equations ◽

Forced Convection ◽

Heat Generation ◽

Numerical Study ◽

Porous Plate ◽

Integration Scheme ◽

Suction Parameter ◽

Transfer Flow

The problem of combined free-forced convection and mass transfer flow over a vertical porous flat plate, in presence of heat generation and thermaldiffusion, is studied numerically. The non-linear partial differential equations and their boundary conditions, describing the problem under consideration, are transformed into a system of ordinary differential equations by using usual similarity transformations. This system is solved numerically by applying Nachtsheim-Swigert shooting iteration technique together with Runge-Kutta sixth order integration scheme. The effects of suction parameter, heat generation parameter and Soret number are examined on the flow field of a hydrogen-air mixture as a non-chemical reacting fluid pair. The analysis of the obtained results showed that the flow field is significantly influenced by these parameters.

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