The Relationship of Normal and Abnormal Microstructural Proliferation to the Mitral Valve Closure Sound

2005 ◽  
Vol 127 (1) ◽  
pp. 134-147 ◽  
Author(s):  
Daniel R. Einstein ◽  
Karyn S. Kunzelman ◽  
Per G. Reinhall ◽  
Mark A. Nicosia ◽  
Richard P. Cochran
Keyword(s):  
Mitral Valve ◽  
Volume Fraction ◽  
Contrast Material ◽  
Element Model ◽  
Peak Frequency ◽  
Material Behavior ◽  
Small Scale ◽  
Valve Closure ◽  
Valvular Function ◽  
The Relationship

Background : Many diseases that affect the mitral valve are accompanied by the proliferation or degradation of tissue microstructure. The early acoustic detection of these changes may lead to the better management of mitral valve disease. In this study, we examine the nonstationary acoustic effects of perturbing material parameters that characterize mitral valve tissue in terms of its microstructural components. Specifically, we examine the influence of the volume fraction, stiffness and splay of collagen fibers as well as the stiffness of the nonlinear matrix in which they are embedded. Methods and Results: To model the transient vibrations of the mitral valve apparatus bathed in a blood medium, we have constructed a dynamic nonlinear fluid-coupled finite element model of the valve leaflets and chordae tendinae. The material behavior for the leaflets is based on an experimentally derived structural constitutive equation. The gross movement and small-scale acoustic vibrations of the valvular structures result from the application of physiologic pressure loads. Material changes that preserved the anisotropy of the valve leaflets were found to preserve valvular function. By contrast, material changes that altered the anisotropy of the valve were found to profoundly alter valvular function. These changes were manifest in the acoustic signatures of the valve closure sounds. Abnormally, stiffened valves closed more slowly and were accompanied by lower peak frequencies. Conclusion: The relationship between stiffness and frequency, though never documented in a native mitral valve, has been an axiom of heart sounds research. We find that the relationship is more subtle and that increases in stiffness may lead to either increases or decreases in peak frequency depending on their relationship to valvular function.

scholarly journals Parameters in Multiphase Flowing of Natural Gas NGH Slurry via Vertical Pipe

2016 ◽  
Vol 2016 ◽  
pp. 1-7
Author(s):  
Dai Maolin ◽  
Wu Kaisong
Keyword(s):  
Pressure Drop ◽  
Natural Gas ◽  
Simulation Model ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Solid Particles ◽  
Small Scale ◽  
Vertical Pipe ◽  
Particle Volume ◽  
The Relationship

In recent years, the pipeline flowing of natural gas hydrate (hereinafter NGH) slurry has been a promising technique of multiphase flowing via pipe and that of crushed hydrate mixture slurry is also a key technique in solid fluidization mining method of nondiagenetic NGH reservoir below the seabed. In this paper, by using similarity rules, a small-scale simulation model was established to shorten the calculation time. The correctness of the simulation model has been verified through comparison with experiment. Thereby, the distribution of velocity and volume fraction of each phase in the vertical pipe was obtained, and the prototype of vertical pipe was analyzed. By study on the pipe resistance, the pressure drop of slurry, when flowing in vertical pipe, could be calculated asΔP=ρgh+0.23Cρv1.8. In the end, by adjusting volume fraction of particles in the mixture slurry, the relationship between the solid particles’ volume fraction and piezometric pressure drop was obtained. When the optimal flow velocity of the slurry is 2 m/s and the ratio of NGH volume fraction to that of sand is 4 : 1, the optimal particle volume fraction ranges from 20% to 40%.

Strength Analyses of Sandwich Pipes for Ultra Deepwaters

2004 ◽  
Vol 72 (4) ◽  
pp. 599-608 ◽  
Author(s):  
Segen Farid Estefen ◽  
Theodoro Antoun Netto ◽  
Ilson Paranhos Pasqualino
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Ultimate Strength ◽  
Thermal Insulation ◽  
Research Work ◽  
Element Model ◽  
Material Behavior ◽  
Core Material ◽  
Small Scale ◽  
Mechanical Resistance

Design requirements for pipelines regarding both ultimate strength and flow assurance in ultra deepwater scenarios motivated the development of a new sandwich pipe which is able to combine high structural and thermal insulation properties. In this concept, the annulus is filled with low cost materials with adequate thermal insulation properties and good mechanical resistance. The aim of this research work is to perform small-scale laboratorial tests and to develop a finite element model to evaluate the structural performance of such sandwich pipes with two different options of core material. After calibrated in view of the experimental results, a three-dimensional finite element model incorporating nonlinear geometric and material behavior is employed to perform strength analyses of sandwich pipes under combined external pressure and longitudinal bending. Ultimate strength envelopes for sandwich pipes are compared with those generated for single-wall steel pipes with equivalent collapse pressures. The study shows that sandwich pipe systems with either cement or polypropylene cores are feasible options for ultra deepwater applications.

scholarly journals The relationship of the first heart sound to mitral valve closure in dogs.

Circulation ◽  
1982 ◽  
Vol 66 (1) ◽  
pp. 235-243 ◽  
Author(s):  
L F Wexler ◽  
G M Pohost ◽  
J J Rubenstein ◽  
D D O'Keefe ◽  
M P Vezeridis ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Heart Sound ◽  
Valve Closure ◽  
First Heart Sound ◽  
Relationship Of ◽  
The Relationship

scholarly journals Calculation of the Flux Density Function for Protein Crystals from Small Scale Settling and Filtration Experiments

2021 ◽  
Author(s):  
Benjamin Radel ◽  
Tu Hoang Nguyen ◽  
Hermann Nirschl
Keyword(s):  
Density Function ◽  
Flux Density ◽  
Mechanical Stability ◽  
Volume Fraction ◽  
Material Behavior ◽  
Protein Crystals ◽  
Industrial Processes ◽  
Small Scale ◽  
Compressible Material ◽  
Filtration Properties

Development and engineering of protein crystals regarding mechanical stability and crystallizability occurs on a small scale. Later in the process chain of industrial production however, filtration properties are important to separate the crystals from mother liquor. Many protein crystals are sensitive to mechanical stress which is why it is important to know the filtration behavior early on. In this study we analyze settling and filtration behavior of isometric, rod-like and needle shaped lysozyme and rod-like alcohol dehydrogenase (ADH) crystals on a small scale using an optical analytical centrifuge. Needle shaped lysozyme and rod-like ADH crystals show compressible material behavior. With the results from settling and filtration experiments the flux density function is calculated and modeled which can be used to describe the whole settling and permeation process in dependency of the solids volume fraction. This is also an issue for simulations of industrial processes.

A Complex Mitral Valve Reconstruction: A Case Report

2005 ◽  
Vol 6 (2) ◽  
pp. 27
Author(s):  
Dimitrios Buklas ◽  
Massimo Massetti ◽  
Eric Saloux ◽  
Eugenio Neri ◽  
Olivier LePage ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Surgical Techniques ◽  
Mitral Valve Insufficiency ◽  
Left Ventricular ◽  
Mitral Valve Reconstruction ◽  
Mitral Repair ◽  
Valve Reconstruction ◽  
Valve Insufficiency ◽  
Valve Function ◽  
Valvular Function

Several techniques are currently in use for mitral valve reconstruction. We report a mitral repair case in which the use of a combination of different surgical techniques resulted in the necessary correction. A 47-year-old woman underwent surgical intervention to treat severe mitral valve insufficiency due to A1/A2/A3 and P2 prolapsed valve tissue. A combination of quadrangular resection, sliding leaflet, single chordal transposition, "flip-over" leaflet, and ring annuloplasty techniques were applied, and postsurgical correct valve function was documented by results of a left ventricular saline filling test and transesophageal echocardiography control. Complex mitral valve repairing techniques can be combined to reestablish valvular function.

Quantitative analysis of mitral annulus morphology in aortic stenosis using real time 3-dimentional transesophageal echocardiography

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
W Suzuki ◽  
Y Nakano ◽  
H Ohashi ◽  
H Ando ◽  
K Waseda ◽  
...  
Keyword(s):  
Mitral Valve ◽  
Aortic Stenosis ◽  
Transesophageal Echocardiography ◽  
Real Time ◽  
Mitral Annulus ◽  
Left Ventricular Ejection ◽  
Control Group ◽  
The Impact ◽  
The Relationship ◽  
Saddle Shape

Abstract Background Normal mitral annulus morphology is known to be saddle shape. There are a few reports regarding the relationship between flattening of the mitral annular saddle shape and mitral regurgitation. However, the relationship between aortic stenosis (AS) and mitral annulus morphology is unknown. Purpose To assess the impact of AS on mitral annular saddle shape using 3-dimentional transesophageal echocardiography. Methods A total of consecutive 83 subjects including 44 patients with severe AS (AS group) and 39 patients without AS (control group), who underwent real-time 3-dimentional transesophageal echocardiography of the mitral valve, were enrolled. The 3-dimentional geometry of the mitral annulus apparatus was evaluated by the parameters analyzed using dedicated quantification software such as anteroposterior diameter (APD), commissural width (CW), annular height (AH), mitral annulus (MA) area and annular height to commissural width ratio (AHCWR) as shown in Figure. We assessed the impact of severe AS on AHCWR, which is the key parameter showing flattening of the mitral annular saddle shape. These parameters were adjusted by body surface area (BSA). Exclusion criteria included left ventricular ejection fraction <50%, the presence of aortic regurgitation, mitral valve disease, pericardial or congenital diseases, endocarditis, cardiomyopathy, prior myocardial infarction, and paroxysmal or persistent atrial fibrillation. Results Comparisons of mitral valve geometry between AS group and control group are summarized in Table. AH/BSA and AHCWR were significantly lower in AS group compared with control group. Multiple linear regression analysis revealed severe AS to be a significant and independent predictor of lowering AHCWR (β=−0.39, t=−4.04, p<0.001) (adjusted with MA area, selected by stepwise analysis). Conclusions Severe AS might contribute to flattening of the mitral annular saddle shape, lead to the mitral annular structural remodeling. Assessment of the mitral annulus morphology might help evaluating severe AS. Mitral annulus 3-dimensional geometry Funding Acknowledgement Type of funding source: None

scholarly journals Maternal toxoplasmosis and the risk of childhood autism: serological and molecular small-scale studies

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jamila S. Al Malki ◽  
Nahed Ahmed Hussien ◽  
Fuad Al Malki
Keyword(s):  
Neurodevelopmental Disorders ◽  
Repetitive Behavior ◽  
Saudi Arabian ◽  
Childhood Autism ◽  
Small Scale ◽  
Autistic Children ◽  
High Prevalence ◽  
Life Threatening ◽  
The Relationship ◽  
Delayed Language Development

Abstract Background Toxoplasmosis resulting from infection with the Toxoplasma parasite has become an endemic disease worldwide. Recently, a few studies have reported a high prevalence of Toxoplasmosis infections among Saudi Arabian women. This disease could become life threatening for pregnant women and for immunodeficient people. There is evidence that infections during pregnancy, especially in the early stages, are associated with neurodevelopmental disorders. Autism disorder represents one of the most common neurodevelopmental disorders worldwide; it is associated with delayed language development, weak communication interaction, and repetitive behavior. The relationship between prenatal toxoplasmosis and autism in childhood remains unclear. The present study aims to report a link between maternal toxoplasmosis and autistic offspring among Saudi Arabian women. Method Blood samples (36 maternal, 36 from their non-autistic children, and 36 from their autistic children) were collected for serological and molecular evaluation. Results A toxoplasmosis infection was reported for 33.34% of participants using an ELISA assay (5.56% IgG+/IgM+, 11.11% IgG−/IgM+, and 16.67% IgG+/IgM-); however, a nested PCR assay targeting B1 toxoplasmosis specific genes recorded positive tests for 80.56% of the samples. In addition, the present study detected several points of mutation of mtDNA including NADH dehydrogenase (ND1, ND4) and Cyt B genes and the nDNA pyruvate kinase (PK) gene for autistic children infected with toxoplasmosis. Conclusion Considering previous assumptions, we suggest that a maternal toxoplasmosis infection could have a role in the development of childhood autism linked to mtDNA and nDNA impairment.

Finite Element Model to Predict the Bioconversion Rate of Glucose to Fructose using Escherichia coli K12 for Sugar Production from Date

2015 ◽  
Vol 11 (1) ◽  
pp. 105-113 ◽  
Author(s):  
Maher Trigui ◽  
Karim Gabsi ◽  
Walid Zneti ◽  
Suzelle Barrington ◽  
Ahmed Noureddine Helal
Keyword(s):  
Escherichia Coli ◽  
Induction Time ◽  
Volume Fraction ◽  
Element Model ◽  
Initial Concentration ◽  
Computational Fluids Dynamics ◽  
Date Syrup ◽  
Computational Fluids ◽  
Two Phases ◽  
Inoculum Volume

Abstract In this study, Bioconversion process of glucose to fructose from date syrup using Escherichia coli K12 is modeled using a commercial computational fluids dynamics (CFD) code fluent FLUENT 6.3.23 [8] which we implemented a user-defined functions (UDF) to simulate the interrelationships at play between various phases. A two phases CFD model was developed using an Eulerian – Eulerian approach to calculate the fructose volume fraction produced during time. The bioconversion process was studied as function of three initial concentration of glucose (0.14, 0.242 and 0.463gL–1), three induction time (60, 120 and 180 mn) and three inoculum volume (100, 120 and 150mL). The numerical results are compared with experimental data for bioconversion rate and show good agreement (R2= 0.894). The optimal condition of diffusion was obtained by applying an initial concentration of glucose less than 0.2gL–1 and induction time great than 100 minutes.

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