An experimental study of the relation of cardiac jelly to the shape of the early chick embryonic heart

Development ◽  
1981 ◽  
Vol 65 (1) ◽  
pp. 235-256
Author(s):  
Atsuyo Nakamura ◽  
Francis J. Manasek
Keyword(s):  
Internal Pressure ◽  
Driving Force ◽  
Embryonic Heart ◽  
Heart Region ◽  
Matrix Components ◽  
Dorsal Mesocardium ◽  
Protein Components ◽  
Shape Changes ◽  
Testicular Hyaluronidase

The structural roles of cardiac jelly components were examined in the early developing chick embryonic heart. Cardiac jelly matrix components were enzymically removed in situ by injecting nanogram quantities of enzymes directly into the cardiac jelly. Injection of ovine testicular hyaluronidase caused shrinkage and the heart became flaccid, but overall heart shape did not change. These responses were the result of enzymatic removal of glycosaminoglycan sugar moieties and were not due to lumenal collapse. Although purified collagenase did not cause any noticeable change, enzymes with non-specific proteolytic activity induced marked cardiac shape changes. In such hearts the dorsal mesocardium opened completely, and the myocardium as well as splanchnic mesoderm of foregut detached from their substrata and the entire heart region swelled. Consequently the shape of the heart was altered completely. These results suggested that in the normal condition the myocardial envelope was under an internal pressure due to the presence of glycosaminoglycans in the cardiac jelly space, and that some matrical non-collagenous protein components were essential to control the internal pressure. Therefore it is suggested that the internal pressure of cardiac jelly may be the direct driving force for the looping process and protein components of cardiac jelly may be important in directing the force for the morphogenetic process.

In situ TEM Studies of agglomeration of sub-nanometer Ru layers in Ru/C multilayers

1992 ◽  
Vol 50 (1) ◽  
pp. 256-257
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortright
Keyword(s):  
Layered Structure ◽  
Driving Force ◽  
High Energy ◽  
Superior Performance ◽  
In Situ Tem ◽  
Rayleigh Instability ◽  
Practical Applications ◽  
Transmission Electron ◽  
Diffraction Patterns

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.

Embryonic development of the heart

Development ◽  
1969 ◽  
Vol 22 (3) ◽  
pp. 333-348
Author(s):  
Francis J. Manasek
Keyword(s):  
Cell Layer ◽  
Embryonic Heart ◽  
Outer Cell ◽  
Chick Embryos ◽  
Myocardial Wall ◽  
Undifferentiated Cells ◽  
Epicardial Layer ◽  
Outer Cell Layer ◽  
Heart Wall

The mature heart may be thought of as consisting of three layers, endocardium, myocardium, and an outer investing tissue called the epicardium. During early formation of the tubular heart of chick embryos, at about the 8-somite stage, two tissue layers become clearly discernible with the light microscope: the endocardium and the developing myocardial wall. The outer epicardial layer does not appear until later in development. It is generally accepted that embryonic heart wall or ‘epimyocardium’ is composed of muscle and undifferentiated cells. As its name implies, the epimyocardium is thought to give rise to myocardium and epicardium. Kurkiewicz (1909) suggested that the epicardium was not an epimyocardial derivative but rather is formed from cells originating in the sinus venosus region, which migrate over the surface of the heart. Nevertheless, it has become generally accepted that the outer cell layer of the embryonic heart wall differentiates in situ to give rise to the definitive visceral epicardium (Patten, 1953).

J and CTOD Based Tensile Strain Capacity Prediction for Pipelines with a Surface Crack in Girth Weld

2021 ◽  
Author(s):  
Youn-Young Jang ◽  
Nam-Su Huh ◽  
Ik-Joong Kim ◽  
Young-Pyo Kim
Keyword(s):  
Crack Initiation ◽  
Internal Pressure ◽  
Surface Crack ◽  
Driving Force ◽  
Tensile Strain ◽  
Structural Integrity ◽  
Accurate Estimation ◽  
Long Distance ◽  
Crack Driving Force ◽  
Girth Welding

Abstract Long-distance pipelines for the transport of oil and natural gas to onshore facilities are mainly fabricated by girth welding, which has been considered as a weak location for cracking. Pipeline rupture due to crack initiation and propagation in girth welding is one of the main issues of structural integrity for a stable supply of energy resources. The crack assessment should be performed by comparing the crack driving force with fracture toughness to determine the critical point of fracture. For this reason, accurate estimation of the crack driving force for pipelines with a crack in girth weld is highly required. This paper gives the newly developed J-integral and crack-tip opening displacement (CTOD) estimation in a strain-based scheme for pipelines with an internal surface crack in girth weld under axial displacement and internal pressure. For this purpose, parametric finite element analyses have been systematically carried out for a set of pipe thicknesses, crack sizes, strain hardening, overmatch and internal pressure conditions. Using the proposed solutions, tensile strain capacities (TSCs) were quantified by performing crack assessment based on crack initiation and ductile instability and compared with TSCs from curved wide plate tests to confirm their validity.

Immiscible Two-Phase Parallel Microflow and Its Applications in Fabricating Micro- and Nanomaterials

2021 ◽  
pp. 200-224
Author(s):  
Yujie Li ◽  
Jie Wang ◽  
Shijie Wang ◽  
Di Li ◽  
Shan Song ◽  
...  
Keyword(s):  
Driving Force ◽  
Water Systems ◽  
Liquid Interface ◽  
Parallel Flow ◽  
Two Phase ◽  
Friction Resistance ◽  
Interface Reactions ◽  
Oil Water ◽  
Proper Balance

The immiscible two-phase flow behaves nonlinearly, and it is a challenging task to control and stabilize the liquid-liquid interface. Parallel flow forms under a proper balance between the driving force, the friction resistance, and the interfacial tension. The liquid-solid interaction as well as the liquid-liquid interaction plays an important role in manipulating the liquid-liquid interface. With vacuum-driven flow, long and stable parallel flow is possible to be obtained in oil-water systems and can be used for fabricating micro- and nanomaterials. Ultra-small Cu nanoparticles of 4~10 nm were synthesized continuously through chemical reactions taking place on the interface. This makes it possible for in situ synthesis of conductive nanoink avoiding oxidation. Well-controlled interface reactions can also be used to produce ultra-long sub-micro Cu wires up to 10 mm at room temperature. This method provided new and simple additive fabrication methods for making integrated microfluidic devices.

Toward an understanding of rates of crystal nucleation from solution with a variable driving force

1977 ◽  
Vol 55 (8) ◽  
pp. 1285-1293 ◽  
Author(s):  
Ronald E. Massey ◽  
O. E. Hileman Jr
Keyword(s):  
Driving Force ◽  
Crystal Nucleation ◽  
Time Data ◽  
Large Spread ◽  
Steady State Rate ◽  
State Rate ◽  
Lag Times ◽  
A New Technique ◽  
Individual Droplet

'Number-time' data obtained during studies on the nucleation from aqueous solution of CaSO4•2H2O (gypsum) using the droplet technique and a variable driving force are reported. Sulfate ion was generated, in situ, by the reaction between S2O82− and S2O32− in the presence of Ca2+. The rate of the reaction was determined from polarographic data. The stoichiometry and solubility of the precipitate in the aqueous matrix were determined.Problems which arise during analysis of 'number-time' data obtained from droplet experiments with a large spread in individual droplet volumes and a variable driving force using techniques suggested in the literature are commented upon. A new technique was developed and applied to the analysis of our data. The effects of a non-steady state rate of nucleation, variable lag times and a decreasing cation: anion ratio on the derived results are discussed.

Coherency Strain Energy in any Crystal System: Applications to in Situ Observations of Cigm in Calcite

1990 ◽  
Vol 205 ◽  
Author(s):  
R.S. May ◽  
B. Evans
Keyword(s):  
Driving Force ◽  
Migration Rate ◽  
Strain Energy ◽  
Solute Concentration ◽  
Coherency Strain ◽  
Solute Diffusion ◽  
Boundary Orientation ◽  
In Situ Observations ◽  
And Migration

AbstractIn situ observations of CIGM in CaCO3 bicrystals with a SrCO3 solute source were made. The change in boundary orientation and migration rate were compared with solute concentration. The liquid film model for coherency strain Induced migration was generalized to any non-cubic system and applied to CaCO3-SrCO3. The coherent layer was modeled as a thin film on an infinite half-space. The strain energy was found from solution of the Hooke's law expressions transformed to the appropriate coordinate system. For triclinic or monoclinic films the strain tensor was found by an eigenvector decomposition of the transformation matrix that defined the lattice parameter change with composition. High anisotropy of Vegard's law constants for CaCO3-SrCO3 caused (111) to have the lowest coherency strain per unit solute. Surfaces perpendicular to (111) in coherent equilibria were predicted to have half the solute concentration and three times the migration driving force of those perpendicular to (111). However, no correlation between solute concentration and boundary orientation was observed. Ambiguous and contradictory evidence for a relationship between solute concentration, boundary orientation, and migration rate was found. The self-stress state of a grain boundary in a solute diffusion field may be better modelled as hydrostatic rather than plane stress. Hydrostatic compression may interact with the boundary excess volume and cause a PV driving force for migration. Predictions based on coherent equilibrium at a surface have not been tested for that geometry in calcite; they should be tested before they are applied to grain boundaries.

Effect of Biaxial Stress on Crack Driving Force

2006 ◽  
Author(s):  
G. Shen ◽  
W. R. Tyson
Keyword(s):  
Internal Pressure ◽  
Driving Force ◽  
Axial Stress ◽  
Axial Strain ◽  
Biaxial Stress ◽  
J Integral ◽  
Longitudinal Stress ◽  
Secondary Stress ◽  
Stress Strain ◽  
Strain Equation

A stress-strain equation of Ramberg-Osgood type is proposed to correlate the longitudinal stress with longitudinal strain of a thin plate when a constant stress is applied transversely. The same approach can be used to correlate the axial stress with axial strain for a thin-walled pipe in axial tension with internal pressure. The proposed stress-strain equation relating the longitudinal stress and strain closely approximates that of deformation theory. The effect of a secondary stress (hoop stress) on the J-integral for a circumferential crack in a pipe under axial load and internal pressure is evaluated by finite element analysis (FEA). The results show that the J-integral decreases with internal pressure at a given axial stress but increases with internal pressure at a given axial strain. It is concluded that while a secondary stress may be safely neglected in a stress-based format because it decreases the driving force at a given applied stress, it should not be neglected in a strain-based format because it significantly increases the driving force at a given applied strain.

Sign in / Sign up

Export Citation Format

Share Document