scholarly journals The Z lattice in canine cardiac muscle.

1979 ◽  
Vol 83 (1) ◽  
pp. 187-204 ◽  
Author(s):  
M A Goldstein ◽  
J P Schroeter ◽  
R L Sass
Keyword(s):  
Electron Micrographs ◽  
Cross Sections ◽  
Three Dimensional ◽  
Optical Diffraction ◽  
Section Thickness ◽  
Uniform Lattice ◽  
Cross Sectional ◽  
Regular Arrangement ◽  
Diffraction Patterns ◽  
Three Dimensional Models

Filtered images of mammalian cardiac Z bands were reconstructed from optical diffraction patterns from electron micrographs. Reconstructed images from longitudinal sections show connecting filaments at each 38-nm axial repeat in an array consistent with cross-sectional data. Some reconstructed images from cross sections indicate two distinctly different optical diffraction patterns, one for each of two lattice forms (basket weave and small square). Other images are more complex and exhibit composite diffraction patterns. Thus, the two lattice forms co-exist, interconvert, or represent two different aspects of the same details within the lattice. Two three-dimensional models of the Z lattice are presented. Both include the following features: a double array of axial filaments spaced at 24 nm, successive layers of tetragonally arrayed connecting filaments, projected fourfold symmetry in cross section, and layers of connecting filaments spaced at intervals of 38 nm along the myofibril axis. Projected views of the models are compared to electron micrographs and optically reconstructed images of the Z lattice in successively thicker cross sections. The entire Z band is rarely a uniform lattice regardless of plane of section or section thickness. Optical reconstructions strongly suggest two types of variation in the lattice substructure: (a) in the arrangement of connecting filaments, and (b) in the arrangement of units added side-to-side to make larger myofilament bundles and/or end-to-end to make wider Z bands. We conclude that the regular arrangement of axial and connecting filaments generates a dynamic Z lattice.

scholarly journals Optical diffraction of the Z lattice in canine cardiac muscle.

1977 ◽  
Vol 75 (3) ◽  
pp. 818-836 ◽  
Author(s):  
M A Goldstein ◽  
J P Schroeter ◽  
R L Sass
Keyword(s):  
Cardiac Muscle ◽  
Electron Micrographs ◽  
Cross Sections ◽  
Optical Diffraction ◽  
Square Lattice ◽  
Thin Sections ◽  
Diffraction Patterns ◽  
Nemaline Rods

Optical diffraction patterns from electron micrographs of both longitudinal and cross sections of normal and anomalous canine cardiac Z bands have been compared. The data indicate that anomalous cardiac Z bands resembling nemaline rods are structurally related to Z bands in showing a repeating lattice common to both. In thin sections transverse to the myofibril axis, both electron micrographs and optical diffraction patterns of the Z structure reveal a square lattice of 24 nm. This lattice is simple at the edge of each I band and centered in the interior of the Z band, where two distinct lattice forms have been observed. In longitudinal sections, oblique filaments visible in the electron micrographs correspond to a 38-nm axial periodicity in diffraction patterns of both Z band and Z rod. We conclude that the Z rods will be useful for further analysis and reconstruction of the Z lattice by optical diffraction techniques.

Optical Diffraction Of The Z Lattice In Striated Muscle

1975 ◽  
Vol 33 ◽  
pp. 548-549
Author(s):  
Margaret A. Goldstein ◽  
John P. Schroeter ◽  
Ronald L. Sass
Keyword(s):  
Cross Sections ◽  
Striated Muscle ◽  
Three Dimensional ◽  
Longitudinal Section ◽  
Optical Diffraction ◽  
Crystalline Lattice ◽  
Striated Muscles ◽  
Unit Cells ◽  
Three Dimensional Models ◽  
Rest Length

Each normal striated muscle fiber has a characteristic Z width at rest length. Previous EM studies of thin Z bands in skeletal muscles have led to a variety of three dimensional models. Recent observations based on thicker Z bands have been incorporated into one of these models. As a first step in understanding three dimensional aspects of the Z band we have constructed a model lattice based on observations of cross sections. We are testing the assumption that regardless of the thickness of the Z band at rest length as observed in longitudinal section, the lattice unit cells as viewed in cross section will be simply related.Viewing the Z band as a crystalline lattice suitable for analysis by optical diffraction techniques, we are studying a variety of striated muscles in different physiological and pathological states. Muscles are fixed in paraformaldehyde glutaraldehyde and postfixed in osmium tetroxide.

Light Optical Diffraction Studies of Macromolecular Ultrastructure

1970 ◽  
Vol 28 ◽  
pp. 258-259
Author(s):  
Glen B. Haydon
Keyword(s):  
High Resolution ◽  
Diffraction Analysis ◽  
Diffraction Pattern ◽  
Electron Micrographs ◽  
Optical Diffraction ◽  
Electron Micrograph ◽  
Its Analysis ◽  
Resolution Electron ◽  
Diffraction Patterns

Analysis of light optical diffraction patterns produced by electron micrographs can easily lead to much nonsense. Such diffraction patterns are referred to as optical transforms and are compared with transforms produced by a variety of mathematical manipulations. In the use of light optical diffraction patterns to study periodicities in macromolecular ultrastructures, a number of potential pitfalls have been rediscovered. The limitations apply to the formation of the electron micrograph as well as its analysis.(1) The high resolution electron micrograph is itself a complex diffraction pattern resulting from the specimen, its stain, and its supporting substrate. Cowley and Moodie (Proc. Phys. Soc. B, LXX 497, 1957) demonstrated changing image patterns with changes in focus. Similar defocus images have been subjected to further light optical diffraction analysis.

scholarly journals Thermo-Hydraulic Performance of U-Tube Borehole Heat Exchanger with Different Cross-Sections

2021 ◽  
Vol 13 (6) ◽  
pp. 3255
Author(s):  
Aizhao Zhou ◽  
Xianwen Huang ◽  
Wei Wang ◽  
Pengming Jiang ◽  
Xinwei Li
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Heat Resistance ◽  
Cross Sections ◽  
Three Dimensional ◽  
Thermal Response ◽  
Transfer Efficiency ◽  
Cross Sectional ◽  
Heat Transfer Efficiency ◽  
Oval Tube

For reducing the initial GSHP investment, the heat transfer efficiency of the borehole heat exchange (BHE) system can be enhanced to reduce the number or depth of drilling. This paper proposes a novel and simple BHE design by changing the cross-sectional shape of the U-tube to increase the heat transfer efficiency of BHEs. Specifically, in this study, we (1) verified the reliability of the three-dimensional numerical model based on the thermal response test (TRT) and (2) compared the inlet and outlet temperatures of the different U-tubes at 48 h under the premise of constant leg distance and fluid area. Referent to the circular tube, the increases in the heat exchange efficiencies of the curved oval tube, flat oval tube, semicircle tube, and sector tube were 13.0%, 19.1%, 9.4%, and 14.8%, respectively. (3) The heat flux heterogeneity of the tubes on the inlet and outlet sides of the BHE, in decreasing order, is flat oval, semicircle, curved oval, sector, and circle shapes. (4) The temperature heterogeneity of the borehole wall in the BHE in decreasing order is circle, sector, curved oval, flat oval, and semicircle shapes. (5) Under the premise of maximum leg distance, referent to the heat resistance of the tube with a circle shape at 48 h, the heat exchange efficiency of the curved oval, flat oval, semicircle, and sector tubes increased 12.6%, 17.7%, 10.3%, and 7.8%, respectively. (6) We found that the adjustments of the leg distance and the tube shape affect the heat resistance by about 25% and 12%, respectively. (7) The flat-oval-shaped tube at the maximum leg distance was found to be the best tube design for BHEs.

The Structure of the Macromolecular Units on the Cell Walls of Bacillus Polymyxa

1967 ◽  
Vol 2 (4) ◽  
pp. 587-591
Author(s):  
J. T. FINCH ◽  
A. KLUG ◽  
M.V. NERMUT
Keyword(s):  
Cell Wall ◽  
Electron Micrographs ◽  
Electron Scattering ◽  
Cell Walls ◽  
Single Layer ◽  
Optical Diffraction ◽  
Square Lattice ◽  
Bacillus Polymyxa ◽  
Optical Filtering ◽  
Diffraction Patterns

Electron micrographs of negatively stained preparations of cell walls of Bacillus polymyxa have been investigated by optical diffraction and optical filtering techniques. Images of single layers of the cell wall, from which the ‘noise’ has been filtered optically, show hollow, square-shaped morphological units arranged on a square lattice of side 100 Å. Single-layer images showing the same pattern have been filtered from moiré patterns arising from two overlapping single layers. The morphological units are composed of four smaller subunits. The optical diffraction patterns from regions of two overlapping layers show extra reflexions which are attributed to multiple electron scattering.

Water Entry of a Wedge by Hydroelastic Orthotropic Plate Theory

1999 ◽  
Vol 43 (03) ◽  
pp. 180-193 ◽  
Author(s):  
Odd M. Faltinsen
Keyword(s):  
Impact Velocity ◽  
Cross Sections ◽  
Orthotropic Plate ◽  
Plate Theory ◽  
Three Dimensional ◽  
Water Entry ◽  
Natural Period ◽  
Cross Sectional ◽  
Flow Effects ◽  
The Impact

Water entry of a hull with wedge-shaped cross sections is analyzed. The stiffened platings between two transverse girders on each side of the keel are separately modeled. Orthotropic plate theory is used. The effect of structural vibrations on the fluid flow is incorporated by solving the two-dimensional Laplace equation in the cross-sectional fluid domain by a generalized Wagner's theory. The coupling with the plate theory provides three-dimensional flow effects. The theory is validated by comparison with full-scale experiments and drop tests. The importance of global ship accelerations is pointed out. Hydrodynamic and structural error sources are discussed. Systematic studies on the importance of hydroelasticity as a function of deadrise angle and impact velocity are presented. This can be related to the ratio between the wetting time of the structure and the greatest wet natural period of the stiffened plating. This ratio is proportional to the deadrise angle and inversely proportional to the impact velocity. A small ratio-means that hydroelasticity is important and a large ratio means that hydroelasticity is not important.

Enamel Crystal Shape: History of an Idea

1987 ◽  
Vol 1 (2) ◽  
pp. 322-329 ◽  
Author(s):  
H. Warshawsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cross Sections ◽  
Three Dimensional ◽  
Unit Cell ◽  
Cross Sectional ◽  
Transmission Electron ◽  
History Of ◽  
Sectional Shape ◽  
Imaging Plane

The purpose of this paper is to review evidence which casts doubt on the interpretation universally applied to hexagonal images seen in sectioned enamel. The evidence is based on two possible models to explain the hexagonal profiles seen in mammalian enamel with transmission electron microscopy. The "hexagonal ribbon" model proposes that hexagonal profiles are true cross-sections of elongated hexagonal ribbons. The "rectangular ribbon" model proposes that hexagonal profiles are caused by three-dimensional segments that are parallelepipeds contained in the Epon section. Since shadow projections of such rectangular segments give angles that are inconsistent with the hexagonal unit cell, a model based on ribbons with rhomboidal cut ends and angles of 60 and 120° is proposed. The "rhomboidal ribbon" model projects shadows with angles that are predicted by the unit cell. It is suggested that segments of such crystallites in section project as opaque hexagons on the imaging plane in routine transmission electron microscopy. Morphological observations on crystallites in sections - together with predictions from the hexagonal, rectangular, and rhomboidal ribbon models - indicate that crystallites in rat incisor enamel are flat ribbons with rhomboidal cross-sectional shape. Hexagonal images in electron micrographs of thin-sectioned enamel can result from rhomboidal-ended, parallelepiped-shaped segments of these crystallites projected and viewed as two-dimensional shadows.

Analysis of Insole Geometry and Deformity by Using a Three-Dimensional Image Processing Technique: A Preliminary Study

2019 ◽  
Vol 109 (2) ◽  
pp. 98-107
Author(s):  
Kit-lun Yick ◽  
Wai-ting Lo ◽  
Sun-pui Ng ◽  
Joanne Yip ◽  
Hung-hei Kwan ◽  
...  
Keyword(s):  
Image Processing ◽  
Cross Sections ◽  
Plantar Pressure ◽  
Three Dimensional ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Diabetic Patients ◽  
Clinical Practices ◽  
Cross Sectional ◽  
Orthotic Treatment

Background: Accurate representation of the insole geometry is crucial for the development and performance evaluation of foot orthoses designed to redistribute plantar pressure, especially for diabetic patients. Methods: Considering the limitations in the type of equipment and space available in clinical practices, this study adopted a simple portable three-dimensional (3-D) desktop scanner to evaluate the 3-D geometry of an orthotic insole and the corresponding deformities after the insole has been worn. The shape of the insole structure along horizontal cross sections is defined with 3-D scanning and image processing. Accompanied by an in-shoe pressure measurement system, plantar pressure distribution in four foot regions (hallux, metatarsal heads, midfoot, and heel) is analyzed and evaluated for insole deformity. Results: Insole deformities are quantified across the four foot regions. The hallux region tends to show the greatest changes in shape geometry (17%–50%) compared with the other foot regions after 2 months of insole wear. As a result of insole deformities, plantar peak pressures change considerably (–4.3% to +69.5%) during the course of treatment. Conclusions: Changes in shape geometry of the insoles could be objectively quantified with 3-D scanning techniques and image processing. This investigation finds that, in general, the design of orthotic insoles may not be adequate for diabetic individuals with similar foot problems. The drastic changes in the insole shape geometry and cross-sectional areas during orthotic treatment may reduce insole fit and conformity. An inadequate insole design may also affect plantar pressure reduction. The approach proposed herein, therefore, allows for objective quantification of insole shape geometry, which results in effective and optimal orthotic treatment.

Optical diffraction studies of myofibrillar structure

1971 ◽  
Vol 261 (837) ◽  
pp. 201-208 ◽  
Keyword(s):  
Electron Micrographs ◽  
Focal Length ◽  
Optical Diffraction ◽  
Myofibrillar Proteins ◽  
Electron Micrograph ◽  
X Ray Diffraction ◽  
Optical Filtering ◽  
X Ray ◽  
The Subject ◽  
Diffraction Patterns

We have used the techniques of optical diffraction and optical filtering to study electron micrographs of myofibrils and of paracrystals of myofibrillar proteins. The optical diffraction patterns provide information about periodic structure in the micrographs, and sometimes may reveal periodicities not apparent to the eye. We compare the optical diffraction patterns with the X-ray diffraction patterns obtained from living muscle, and this comparison can assist our interpretation of both the X-ray diffraction patterns and the electron micrographs. The optical diffractometer we have used is essentially similar to those described by Taylor & Lipson (1964), and by Klug & DeRosier (1966). The apparatus incorporates several refinements to facilitate operation. The recombining lens has a focal length, f , of about 1 m, and is placed so that the recombined image is formed at 2 f and has the same size as the subject. The diffraction subjects are not usually the electron micrographs themselves but copies on film. The film is of more uniform optical thickness than the glass electron micrograph, and is less fragile. Moreover, a set of films of varying contrast can be made from one micrograph.

Effect of Cross Aspect Ratio on Flow in Diverging and Converging Microchannels

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
V. S. Duryodhan ◽  
Shiv Govind Singh ◽  
Amit Agrawal
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Aspect Ratio ◽  
Numerical Study ◽  
Three Dimensional ◽  
Hydraulic Diameter ◽  
Working Fluid ◽  
Cross Sectional ◽  
Flow Acceleration ◽  
Three Dimensional Models

Aspect ratio is an important parameter in the study of flow through noncircular microchannel. In this work, three-dimensional numerical study is carried out to understand the effect of cross aspect ratio (height to width) on flow in diverging and converging microchannels. Three-dimensional models of the diverging and converging microchannels with angle: 2–14 deg, aspect ratio: 0.05–0.58, and Reynolds number: 130–280 are employed in the simulations with water as the working fluid. The effects of aspect ratio on pressure drop in equivalent diverging and converging microchannels are studied in detail and correlated to the underlying flow regime. It is observed that for a given Reynolds number and angle, the pressure drop decreases asymptotically with aspect ratio for both the diverging and converging microchannels. At small aspect ratio and small Reynolds number, the pressure drop remains invariant of angle in both the diverging and converging microchannels; the concept of equivalent hydraulic diameter can be applied to these situations. Onset of flow separation in diverging passage and flow acceleration in converging passage is found to be a strong function of aspect ratio, which has not been shown earlier. The existence of a critical angle with relevance to the concept of equivalent hydraulic diameter is identified and its variation with Reynolds number is discussed. Finally, the effect of aspect ratio on fluidic diodicity is discussed which will be helpful in the design of valveless micropump. These results help in extending the conventional formulae made for uniform cross-sectional channel to that for the diverging and converging microchannels.

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