scholarly journals Fabricating a Low-cost and Low-immune Xenogeneic Aortic Valve Bio Prosthesis

2021 ◽  
Author(s):  
Sonal Walawalkar ◽  
Shahdab Almelkar ◽  
Savvas Christoforidis ◽  
Subha N Rath
Keyword(s):  
Aortic Valve ◽  
Low Cost ◽  
Host Proteins ◽  
Aortic Valves ◽  
Prosthetic Valves ◽  
The Matrix ◽  
Characterization Studies ◽  
Cellular Behaviour ◽  
End Stage ◽  
Better Than

Abstract BackgroundCardiac valve replacement is the only available treatment for end-stage valvular dysfunction patients. In this treatment, among the available choices of valves, the bio-prosthetic valves are better than the mechanical ones in terms of hemodynamic and infection-resistant properties. However, they tend to fail with time, posing a catastrophic event. This study focuses on fabricating the heart valve to eliminate the flaws of bio-prosthetic valves. MethodsPerfusion-based decellularization method was adapted for decellularisation to the sheep heart. Further, decellularised aortic valves were cross-linked with 0.2% Glutaraldehyde (Group C). ResultsAll valves were tested for biochemical and molecular assays including biomechanical tensile testing. Histology, SEM showed a complete lack of cells with intact matrix for decellularised groups. The fibrin glue coated valves leaflet scaffolds showed remodeling of the cells as per the matrix (plasticity). Characterization studies emphasized the cellular behaviour onto matrigel assay, live-dead assay, and the expression of vWF, glycocalyx lectin. ConclusionsThis study focuses on fabricating a re-endothelialized xenogeneic aortic valve leaflet using cross-linking reaction to mask antigenicity of the host proteins (low-immune humanized) and avoid post-implantation cross-reaction.

INVESTIGATION OF LEAFLET GEOMETRY IN A PERCUTANEOUS AORTIC VALVE WITH THE USE OF FLUID-STRUCTURE INTERACTION SIMULATION

2012 ◽  
Vol 12 (01) ◽  
pp. 1250003 ◽  
Author(s):  
K. H. J. VAN ASWEGEN ◽  
A. N. SMUTS ◽  
C. SCHEFFER ◽  
H. S. VH. WEICH ◽  
A. F. DOUBELL
Keyword(s):  
Aortic Valve ◽  
Fluid Structure Interaction ◽  
Von Mises Stress ◽  
Aortic Valves ◽  
Native Valve ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Prosthetic Valves ◽  
Significant Difference ◽  
Von Mises

Prosthetic aortic valves have been used for the replacement of dysfunctional native aortic valves in humans for more than fifty years. Current prosthetic valves have significant limitations and the development of improved aortic valve prostheses remains an important research focus area. This paper investigates one of the newer additions to the family of replacement valves, namely the stented percutaneous valve. An important design aspect of stented percutaneous valves, is the configuration of the leaflet's attachment to the surrounding stent. There are essentially two possible configurations: The first method is attaching the leaflets in a straight configuration, and the second method is to attach the leaflets in a curved configuration. Finite element models of both configurations were created, and the behavior of these configurations was then studied using a fluid-structure interaction (FSI) simulation. The FSI simulation was validated by means of comparing simulation results to actual measurements from a pulse duplicator using prototype valves of both configurations. The FSI results showed no significant difference between the valves' opening and closing behaviors. The von Mises stress distributions proved to be the largest differentiating and decisive factor between the two valves. The FSI simulations did however show that the leaflets that are attached in the straight configuration form folds that resembles that of the curved configuration as well as the native valve, but to a larger scale. The effect that these folds might have on valve tissue fatigue leaves room for future investigation.

scholarly journals Miniaturization Design for 8 × 8 Butler Matrix Based on Back-to-Back Bilayer Microstrip

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Yu Zhai ◽  
Xiaoxing Fang ◽  
Kejia Ding ◽  
Fei He
Keyword(s):  
Power Distribution ◽  
Phase Shifter ◽  
Low Cost ◽  
Phase Error ◽  
Butler Matrix ◽  
Relative Bandwidth ◽  
Indoor Wireless ◽  
The Matrix ◽  
Fixed Phase ◽  
Better Than

A low-cost, compact 8 × 8 Butler matrix based on a novel bilayer microstrip configuration is presented and implemented for 4.3 GHz telecommunication application. A back-to-back placed bilayer microstrip structure has been proposed to avoid using crossover. To expand operational bandwidth of the Butler matrix, a three-branch line directional coupler has been employed as 3 dB/90° bridge, and a kind of improved two-order Schiffman phase shifter has been adopted as fixed phase shifter. For application of indoor wireless communication, a compact broadband 8 × 8 Butler matrix has been designed and fabricated. The measured results show that the return loss of the matrix is lower than −10 dB, the isolation is better than 17 dB, the power distribution error is less than ±2.0 dB, the phase error is less than ±15°, and the relative bandwidth is more than 23%.

An Assessment of Ca-Naphthenate-Epon Mixtures as Standards for Calcium Quantification in Aortic Valve Leaflets

1982 ◽  
Vol 40 ◽  
pp. 390-391
Author(s):  
Kathryn N. Colonna ◽  
Sydney S. Breese ◽  
Susan C. Sellers ◽  
J. David Deck
Keyword(s):  
Aortic Valve ◽  
Aortic Valves ◽  
X Ray ◽  
Aortic Valve Leaflets

Qualitative x-ray microanalytical studies used to demonstrate calcium in bioprosthetic aortic valves have shown that it occurs in a range of morphological forms. A consistent and reproducible standard for measuring calcium was necessary to investigate whether these forms represented varying concentrations of calcium. To provide such a standard, we tested a series of calcium naphthenate-epon mixtures.

Kajian Model Fisik Pengaruh Freeboard dan Susunan Buis Beton Sebagai Pemecah Gelombang Tenggelam Ambang Rendah (Pegar) Dalam Mereduksi Gelombang

2017 ◽  
Vol 1 (2) ◽  
pp. 34
Author(s):  
Zulkarnain Zulkarnain ◽  
Nadjadji Anwar
Keyword(s):  
Low Cost ◽  
Relative Depth ◽  
Submerged Breakwater ◽  
Wave Flume ◽  
Concrete Cylinder ◽  
Engineering Department ◽  
Sea Area ◽  
The Waves ◽  
Transmission Test ◽  
Better Than

The Research Center and Development of Water (Puslitbang) is currently developing the Submerged Breakwater in shallow sea area (PEGAR). The author is interested to examine the material that easily obtained in the field of RCP concrete cylinder. The observation is how it to be ability in function as submerged breakwater an go green and low cost. The physical model of wave transmission test is how the response to the structure in ability to damping of wave as the breakwater function. In this research breakwater used is submerged breakwater type by using concrete cylinder (buis beton). The purpose from this research is to know how the response of breakwater structure to the waves through it, with some variation of the structure by creating a structure with three variations of the arrangement and freeboard that is the relative depth with the crest width is constant. The wave generated test in this study is using regular waves in wave flume at FTSP Civil Engineering Department of Institute Technology Ten November. From the analysis of the effect of the installation of submerged breakwater by using concrete cylinder to the wave damping value, it can be concluded that the factors that are very influential is the freeboard and the composition of concrete cylinder. Scenario A (rigid vertical massive) is capable of producing the smallest value of kt is 0.33. As for scenario B (rigid horyzontal massive) with a damping value of 0.5, while the scenario C (rigid permeable) is only able to produce kt value of 0.71. Scenario A is better than scenario B and C Because the position of arrangement of A is very good used to damp wave in small or big freeboard conditions.

A Novel Wideband transition from Substrate Integrated Waveguide to Rectangular Waveguide

2020 ◽  
Vol 10 ◽  
Author(s):  
Keyur Mahant ◽  
Hiren Mewada ◽  
Amit Patel ◽  
Alpesh Vala ◽  
Jitendra Chaudhari
Keyword(s):  
Rectangular Waveguide ◽  
Printed Circuit Board ◽  
Low Cost ◽  
Single Layer ◽  
Circuit Board ◽  
Substrate Integrated Waveguide ◽  
Ka Band ◽  
Better Than ◽  
Millimeter Wave Circuits ◽  
Wideband Transition

Aim: In this article, wideband substrate integrated waveguide (SIW) and rectangular waveguide (RWG) transition operating in Ka-band is proposed Objective: In this article, wideband substrate integrated waveguide (SIW) and rectangular waveguide (RWG) transition operating in Ka-band is proposed. Method: Coupling patch etched on the SIW cavity to couple the electromagnetic energy from SIW to RWG. Moreover, metasurface is introduced into the radiating patch to enhance bandwidth. To verify the functionality of the proposed structure back to back transition is designed and fabricated on a single layer substrate using standard printed circuit board (PCB) fabrication technology. Results: Measured results matches with the simulation results, measured insertion loss is less than 1.2 dB and return loss is better than 3 dB for the frequency range of 28.8 to 36.3 GHz. By fabricating transition with 35 SRRs bandwidth of the proposed transition can be improved. Conclusion: The proposed transition has advantages like compact in size, easy to fabricate, low cost and wide bandwidth. Proposed structure is a good candidate for millimeter wave circuits and systems.

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