A Model for Bone Resorption

2006 ◽  
Author(s):  
Lars Johansson ◽  
Ulf Edlund ◽  
Anna Fahlgren ◽  
Per Aspenberg
Keyword(s):  
Fluid Flow ◽  
Bone Resorption ◽  
Constitutive Model ◽  
Bone Tissue ◽  
Driving Force ◽  
Strain State ◽  
Bone Remodelling ◽  
Fluid Pressure ◽  
Fluid Flow Velocity ◽  
Surgical Implants

In the present paper a model for the resorption of bone, such as that observed at the interface between surgical implants and bone tissue, is developed. While there are many previous studies where models for bone remodelling calculations are proposed, these have been based on the stress or strain state of the bone tissue itself as the driving force for bone remodelling. We, instead, develop a constitutive model based on observations in recent experiments where it seems that fluid pressure, or possibly fluid flow velocity, is a major factor in the bone resorption process.

Bone Resorption Induced by Fluid Flow

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
Lars Johansson ◽  
Ulf Edlund ◽  
Anna Fahlgren ◽  
Per Aspenberg
Keyword(s):  
Fluid Flow ◽  
Soft Tissue ◽  
Bone Resorption ◽  
Energy Density ◽  
Fluid Pressure ◽  
Time History ◽  
State Of Stress ◽  
Fluid Flow Velocity ◽  
History Of ◽  
Tissue Interface

A model where bone resorption is driven by stimulus from fluid flow is developed and used as a basis for computer simulations, which are compared with experiments. Models for bone remodeling are usually based on the state of stress, strain, or energy density of the bone tissue as the stimulus for remodeling. We believe that there is experimental support for an additional pathway, where an increase in the amount of osteoclasts, and thus osteolysis, is caused by the time history of fluid flow velocity, fluid pressure, or other parameters related to fluid flow at the bone/soft tissue interface of the porosities in the bone.

Calcium-dependent complications of lactase deficiency in patients with type 2 diabetes mellitus

2021 ◽  
Author(s):  
A. B. Andrusha
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Bone Resorption ◽  
Bone Tissue ◽  
Bone Remodelling ◽  
Osteoporotic Fractures ◽  
Lactase Deficiency ◽  
X Ray

Objective — to assess the degree of osteodeficiency and probability of osteoporotic fractures in patients with type 2 diabetes mellitus in the absence or presence of lactase deficiency. Materials and methods. All examined patients with type 2 diabetes mellitus were divided into 2 groups depending on the presence/absence of lactase deficiency. In addition to routine examination methods, specific methods were used for diagnosing lactase deficiency, assessing bone mineral density (using dual‑energy X‑ray absorptiometry) and bone quality (ultrasound densitometry), the state of bone remodelling (according to markers of bone resorption and formation), probability of osteoporotic fractures (using FRAX and QFracture calculators), dietary and lifestyle habits were also studied. Results. The changes have been revealed in both processes of bone remodelling — increased bone resorption and insufficient bone formation, and the activity of bone formation, which was the lowest in patients with lactase deficiency and type 2 diabetes mellitus. The results of X‑ray absorptiometry confirmed that osteoporosis was significantly more often in patients with type 2 diabetes mellitus in the presence of lactase deficiency. The use of ultrasonic densitometry confirmed the violation of bone tissue micro architectonics. The indicator of broadband ultrasound attenuation, which reflects the qualitative characteristics of bone tissue, was the lowest in patients with type 2 diabetes mellitus accompanied by lactase deficiency. The probability of osteoporotic fractures according to the results of the assessment with the online calculator FRAX® was higher than the average risk in both groups of patients. No significant difference was established in this indicator between these groups of patients in contrast to the risk calculated with the QFracture instrument — it was the highest in patients with lactase deficiency. Conclusions. The presence of lactase deficiency in patients with type 2 diabetes mellitus can be considered as a factor that contributes to the development of osteodeficiency, deterioration of the quality of bone tissue, imbalance in bone remodelling and an increase in the probability of osteoporotic fractures.  

scholarly journals Fluid pressure evolution during the earthquake cycle controlled by fluid flow and pressure solution crack sealing

2002 ◽  
Vol 54 (11) ◽  
pp. 1139-1146 ◽  
Author(s):  
Jean-Pierre Gratier ◽  
Pascal Favreau ◽  
François Renard ◽  
Eric Pili
Keyword(s):  
Fluid Flow ◽  
Fluid Pressure ◽  
Pressure Solution ◽  
Earthquake Cycle ◽  
Crack Sealing ◽  
Pressure Evolution

The Further Exploration of Applying Small-Strain and Large-Strain Formulations to SMA

2012 ◽  
Vol 529 ◽  
pp. 228-235
Author(s):  
Jie Yao ◽  
Yong Hong Zhu
Keyword(s):  
Phase Transformation ◽  
Constitutive Model ◽  
Uniaxial Tension ◽  
Driving Force ◽  
Research Team ◽  
Large Strain ◽  
Small Deformation ◽  
Small Strain ◽  
Proportional Loading ◽  
The Difference

Recently, our research team has been considering to applying shape memory alloys (SMA) constitutive model to analyze the large and small deformation about the SMA materials because of the thermo-dynamics and phase transformation driving force. Accordingly, our team use simulations method to illustrate the characteristics of the model in large strain deformation and small strain deformation when different loading, uniaxial tension, and shear conditions involve in the situations. Furthermore, the simulation result unveils that the difference is nuance concerning the two method based on the uniaxial tension case, while the large deformation and the small deformation results have huge difference based on shear deformation case. This research gives the way to the further research about the constitutive model of SMA, especially in the multitiaxial non-proportional loading aspects.

Time Constraints on Seepage Through Fractured Regions on the Vestnesa Ridge off the W-Svalbard Coast

2021 ◽  
Author(s):  
Hariharan Ramachandran ◽  
Andreia Plaza-Faverola ◽  
Hugh Daigle ◽  
Stefan Buenz
Keyword(s):  
Fluid Flow ◽  
Effective Stress ◽  
Gas Hydrate ◽  
Fluid Pressure ◽  
Fracture Network ◽  
The Arctic ◽  
Stability Zone ◽  
Methane Seepage ◽  
Carbonate Formation ◽  
Hydrate Stability

<p>Evidences of subsurface fluid flow-driven fractures (from seismic interpretation) are quite common at Vestnesa Ridge (around 79ºN in the Arctic Ocean), W-Svalbard margin. Ultimately, the fractured systems have led to the formation of pockmarks on the seafloor. At present day, the eastern segment of the ridge has active pockmarks with continuous methane seep observations in sonar data. The pockmarks in the western segment are considered inactive or to seep at a rate that is harder to identify. The ridge is at ~1200m water depth with the base of the gas hydrate stability zone (GHSZ) at ~200m below the seafloor. Considerable free gas zone is present below the hydrates. Besides the obvious concern of amount and rates of historic methane seeping into the ocean biosphere and its associated effects, significant gaps exist in the ability to model the processes of flow of methane through this faulted and fractured region. Our aim is to highlight the interactions between physical flow, geomechanics and geological control processes that govern the rates and timing of methane seepage.</p><p>For this purpose, we performed numerical fluid flow simulations. We integrate fundamental mass and component conservation equations with a phase equilibrium approach accounting for hydrate phase boundary effects to simulate the transport of gas from the base of the GHSZ through rock matrix and interconnected fractures until the seafloor. The relation between effective stress and fluid pressure is considered and fractures are activated once the effective stress exceeds the tensile limit. We use field data (seismic, oedometer tests on calypso cores, pore fluid pressure and temperature) to constrain the range of validity of various flow and geomechanical parameters in the simulation (such as vertical stress, porosity, permeability, saturations).</p><p>Preliminary results indicate fluid overpressure greater than 1.5 MPa is required to initiate fractures at the base of the gas hydrate stability zone for the investigated system. Focused fluid flow occurs through the narrow fracture networks and the gas reaches the seafloor within 1 day. The surrounding regions near the fracture network exhibit slower seepage towards the seafloor, but over a wider area. Advective flux through the less fractured surrounding regions, reaches the seafloor within 15 years and a diffusive flux reaches within 1200 years. These times are controlled by the permeability of the sediments and are retarded further due to considerable hydrate/carbonate formation during vertical migration. Next course of action includes constraining the methane availability at the base of the GHSZ and estimating its impact on seepage behavior.</p>

scholarly journals A dual sensor device to estimate fluid flow velocity at diffuse hydrothermal vents

2009 ◽  
Vol 56 (11) ◽  
pp. 2065-2074 ◽  
Author(s):  
J. Sarrazin ◽  
P. Rodier ◽  
M.K. Tivey ◽  
H. Singh ◽  
A. Schultz ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Flow Velocity ◽  
Hydrothermal Vents ◽  
Sensor Device ◽  
Fluid Flow Velocity ◽  
Dual Sensor

scholarly journals Stress strain state of elastic plate with elliptical cut-out

2020 ◽  
pp. 3-8
Author(s):  
E.E. Deryugin ◽  
Keyword(s):  
Plastic Deformation ◽  
Stress Concentration ◽  
Driving Force ◽  
Strain State ◽  
Mechanical State ◽  
Concentration Coefficient ◽  
Stress Strain ◽  
Crack Driving Force ◽  
Stress Strain State ◽  
Stress Concentration Coefficient

The article considers a crack in the form of a narrow cut with a certain cfn at the cut out in an unbounded plate. The characteristics of the mechanical state of this system under uniaxial loading are determined: the stress concentration coefficient, the crack-driving force, and the energy of a solid with a crack. The elastic energy expenditure during crack propagation is determined. The general regularities of the mechanical state of a solid with a crack, not necessary having the form of an ellipse, are revealed. An important parameter of a crack is the curvature at the tip. It is shown that the Griffiths crack does not actually have a singularity at the tip. The stress strain state of the plate with an elliptical crack is identical to the same of the plate with a focus of homogeneous plastic deformation.

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