scholarly journals Incorporation of Fibrin Matrix into Electrospun Membranes for Periodontal Wound Healing

2019 ◽  
Vol 6 (3) ◽  
pp. 57 ◽  
Author(s):  
Choyi Wong ◽  
Suyog Yoganarasimha ◽  
Caroline Carrico ◽  
Parthasarathy Madurantakam
Keyword(s):  
Mechanical Properties ◽  
Three Dimensional ◽  
Fresh Frozen Plasma ◽  
Biologically Active ◽  
Uniaxial Tensile ◽  
Electrospun Membrane ◽  
Fibrin Matrix ◽  
Uniaxial Tensile Testing ◽  
Electrospun Membranes ◽  
Fresh Frozen

Guided tissue regeneration (GTR) aims to regenerate the lost attachment apparatus caused by periodontal disease through the use of a membrane. The goal of this study is to create and characterize a novel hybrid membrane that contains biologically active fibrin matrix within a synthetic polycaprolactone (PCL) electrospun membrane. Three-dimensional fibrin matrices and fibrin-incorporated electrospun membrane were created from fresh frozen plasma by centrifugation in glass vials under three different conditions: 400 g for 12 min, 1450 g for 15 min and 3000 g for 60 min. Half the membranes were crosslinked with 1% genipin. Degradation against trypsin indicated biologic stability while uniaxial tensile testing characterized mechanical properties. Continuous data was analyzed by ANOVA to detect differences between groups (p = 0.05). Fibrin-incorporated electrospun membranes showed statistically significant increase in mechanical properties (elastic modulus, strain at break and energy to break) compared to fibrin matrices. While crosslinking had marginal effects on mechanical properties, it did significantly increase biologic stability against trypsin (p < 0.0001). Lastly, membranes generated at 400 g and 1450 g were superior in mechanical properties and biologic stability compared to those generated at 3000 g. Fibrin-incorporated, crosslinked electrospun PCL membranes generated at lower centrifugation forces offers a novel strategy to generate a potentially superior membrane for GTR procedures.

Structure Assessment Using Instrumented Indentation: Strength, Toughness and Residual Stress

2018 ◽  
Author(s):  
Dongil Kwon ◽  
Jong Hyoung Kim ◽  
Ohmin Kwon ◽  
Woojoo Kim ◽  
Sungki Choi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Residual Stress ◽  
Tensile Properties ◽  
Hole Drilling ◽  
Uniaxial Tensile ◽  
Small Scale ◽  
Specimen Preparation ◽  
Instrumented Indentation ◽  
Uniaxial Tensile Testing

The instrumented indentation technique (IIT) is a novel method for evaluating mechanical properties such as tensile properties, toughness and residual stress by analyzing the indentation load-depth curve measured during indentation. It can be applied directly on small-scale and localized sections in industrial structures and structural components since specimen preparation is very easy and the experimental procedure is nondestructive. We introduce the principles for measuring mechanical properties with IIT: tensile properties by using a representative stress and strain approach, residual stress by analyzing the stress-free and stressed-state indentation curves, and fracture toughness of metals based on a ductile or brittle model according to the fracture behavior of the material. The experimental results from IIT were verified by comparing results from conventional methods such as uniaxial tensile testing for tensile properties, mechanical saw-cutting and hole-drilling methods for residual stress, and CTOD test for fracture toughness.

Mechanical Characterization of Polymer Nanowires Using MEMS

2006 ◽  
Author(s):  
B. A. Samuel ◽  
Bo Yi ◽  
R. Rajagopalan ◽  
H. C. Foley ◽  
M. A. Haque
Keyword(s):  
Mechanical Properties ◽  
Tensile Testing ◽  
Furfuryl Alcohol ◽  
Mechanical Characterization ◽  
Uniaxial Tensile ◽  
Testing Device ◽  
Uniaxial Tensile Testing ◽  
Polymer Nanowires

We present results on the mechanical properties of single freestanding poly-furfuryl alcohol (PFA) nanowires (aspect ratio &gt; 50, diameters 100–300 nm) from experiments conducted using a MEMS-based uniaxial tensile testing device in-situ inside the SEM. The specimens tested were pyrolyzed PFA nanowires (pyrolyzed at 800° C).

Microstructures and Mechanical Properties of Stainless Steel AISI 316L Processed by Selective Laser Melting

2014 ◽  
Vol 783-786 ◽  
pp. 898-903 ◽  
Author(s):  
Anne Mertens ◽  
Sylvie Reginster ◽  
Quentin Contrepois ◽  
Thierry Dormal ◽  
Olivier Lemaire ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Selective Laser Melting ◽  
Uniaxial Tensile ◽  
Layer By Layer ◽  
Aisi 316L ◽  
Laser Melting ◽  
Uniaxial Tensile Testing ◽  
Steel Aisi ◽  
Stainless Steel Aisi

In this study, samples of stainless steel AISI 316L have been processed by selective laser melting, a layer-by-layer near-net-shape process allowing for an economic production of complex parts. The resulting microstructures have been characterised in details in order to reach a better understanding of the solidification and consolidation processes. The influence of the processing parameters on the mechanical properties was investigated by means of uniaxial tensile testing performed on samples produced with different main orientations with respect to the building direction. A strong anisotropy of the mechanical behaviour was thus interpreted in relation with the microstructures and the processing conditions.

scholarly journals Embossed Membranes with Vascular Patterns Guide Vascularization in a 3D Tissue Model

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 792 ◽  
Author(s):  
Soyoung Hong ◽  
Eun Young Kang ◽  
Jaehee Byeon ◽  
Sung-ho Jung ◽  
Changmo Hwang
Keyword(s):  
Blood Vessel ◽  
Three Dimensional ◽  
Vascular Endothelial ◽  
Electrospun Membrane ◽  
Tissue Constructs ◽  
Vacuum Forming ◽  
Electrospun Membranes ◽  
Vascular Structures ◽  
Endothelial Growth Factor ◽  
Flat Membranes

The vascularization of three-dimensional (3D) tissue constructs is necessary for transporting nutrients and oxygen to the component cells. In this study, a vacuum forming method was applied to emboss a vascular pattern on an electrospun membrane so that guided vascular structures could develop within the construct. Two- or six-layer constructs of electrospun membranes seeded with endothelial cells and pericytes were stacked and subcutaneously implanted into mice. Blood vessel formation in the implanted constructs with six alternating layers of flat membranes and membranes embossed with a blood vessel pattern was observed after two weeks of implantation. The formation of blood vessels was observed along the embossed blood vessel pattern in the structure of the embossed membrane laminated at four weeks and eight weeks. Vascular endothelial growth factor (VEGF) and angiopoietin 1 (Ang-1) were highly expressed in the vascularized structures. Therefore, we demonstrated that a structure capable of producing a desired blood vessel shape with electrospun membranes embossed with a blood vessel pattern can be manufactured, and that a variety of structures can be manufactured using electrospun membranes in the tissue engineering era.

Effect of the Stretch Rate During Uniaxial Testing on the Mechanical Properties of Prolene®

2012 ◽  
Author(s):  
T. M. Bazi ◽  
A. H. Ammouri ◽  
R. F. Hamade
Keyword(s):  
Mechanical Properties ◽  
Tensile Testing ◽  
Relative Elongation ◽  
Testing Machine ◽  
Peak Load ◽  
Displacement Rate ◽  
Uniaxial Tensile ◽  
P Value ◽  
Stretch Rate ◽  
Uniaxial Tensile Testing

We assess the effects of stretch rate on the mechanical properties of Prolene® (Ethicon, Gynecare, Somerville, NJ, USA), a knitted polypropylene mesh. Prolene®, consisting of macroporous knitted polypropylene, is considered here as a suitable proxy to midurethral tape (MUT) as well as to many other prosthesis products used in surgery applications. Such products are utilized to treat urine incontinence, pelvic organ prolapse, as well as hernia in humans. Of the mechanical properties of special significance are the following three properties: peak load (N), extension (%) at peak load, and linear stiffness (N/mm). Uniaxial tensile testing was performed on mesh samples on a universal testing machine and involved loading different samples at 5 cross-head speeds of: 1, 10, 50, 100, and 500 mm/min. The corresponding properties were measured under these 5 conditions. In order to minimize damage to the specimens at the jaws, special dual action pneumatically operated grips with rubber faced jaws were used to hold the samples in place. The effectiveness of these grips was illustrated by the fact that none of the failed samples broke at grips. Statistically significant findings suggest an increasing trend for Prolene® stiffness vs. stretch rate (R2 = 0.9679; two-tailed p value = 0.0025) where the stiffness increases 26.2% when increasing the displacement rate from 1 to 500 mm/min. For extension (%) at peak load, a decreasing trend was found vs. stretch rate (R2 = 0.81; two-tailed p value = 0.037) where increasing the displacement rate from 1 mm/min to 500 mm/min corresponds to a 22% decrease in the relative elongation of the mesh. No statistically significant dependence of peak load on stretch rate was found. These findings may help workers in the biomedical field develop suitable uniaxial tensile testing protocols of such materials.

scholarly journals Experimental Study of Anisotropic Stress/Strain Relationships of Aortic and Pulmonary Artery Homografts and Synthetic Vascular Grafts

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Yueqian Jia ◽  
Yangyang Qiao ◽  
I. Ricardo Argueta-Morales ◽  
Aung Maung ◽  
Jack Norfleet ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Pulmonary Artery ◽  
True Strain ◽  
Vascular Grafts ◽  
Uniaxial Tensile ◽  
Cauchy Stress ◽  
Mechanical Coupling ◽  
Biomechanical Behavior ◽  
Uniaxial Tensile Testing ◽  
Synthetic Grafts

Homografts and synthetic grafts are used in surgery for congenital heart disease (CHD). Determining these materials' mechanical properties will aid in understanding tissue behavior when subjected to abnormal CHD hemodynamics. Homograft tissue samples from anterior/posterior aspects, of ascending/descending aorta (AA, DA), innominate artery (IA), left subclavian artery (LScA), left common carotid artery (LCCA), main/left/right pulmonary artery (MPA, LPA, RPA), and synthetic vascular grafts, were obtained in three orientations: circumferential, diagonal (45 deg relative to circumferential direction), and longitudinal. Samples were subjected to uniaxial tensile testing (UTT). True strain-Cauchy stress curves were individually fitted for each orientation to calibrate Fung model. Then, they were used to calibrate anisotropic Holzapfel–Gasser model (R2 > 0.95). Most samples demonstrated a nonlinear hyperelastic strain–stress response to UTT. Stiffness (measured by tangent modulus at different strains) in all orientations were compared and shown as contour plots. For each vessel segment at all strain levels, stiffness was not significantly different among aspects and orientations. For synthetic grafts, stiffness was significantly different among orientations (p < 0.042). Aorta is significantly stiffer than pulmonary artery at 10% strain, comparing all orientations, aspects, and regions (p = 0.0001). Synthetic grafts are significantly stiffer than aortic and pulmonary homografts at all strain levels (p < 0.046). Aortic, pulmonary artery, and synthetic grafts exhibit hyperelastic biomechanical behavior with anisotropic effect. Differences in mechanical properties among vascular grafts may affect native tissue behavior and ventricular/arterial mechanical coupling, and increase the risk of deformation due to abnormal CHD hemodynamics.

scholarly journals Effect of Severe Plastic Deformation on Structure Refinement and Mechanical Properties of the Al-Zn-Mg-Fe-Ni Alloy

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 296
Author(s):  
Irina Brodova ◽  
Dmitriy Rasposienko ◽  
Irina Shirinkina ◽  
Anastasia Petrova ◽  
Torgom Akopyan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
Structure Refinement ◽  
Tensile Yield Strength ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Testing ◽  
Radial Shear Rolling

This paper identifies the mechanisms of phase and structural transformations during severe plastic deformation by shearing under pressure (high-pressure torsion) of an Al-Zn-Mg-Fe-Ni-based aluminum alloy depending on different initial states of the material (an ingot after homogenizing annealing and a rod produced by radial-shear rolling). Scanning and transmission electron microscopy are used to determine the morphological and size characteristics of the structural constituents of the alloy after high-pressure torsion. It has been found that, irrespective of the history under high-pressure torsion, fragmentation and dynamic recrystallization results in a nanostructural alloy with a high microhardness of 2000 to 2600 MPa. Combined deformation processing (high-pressure torsion + radial-shear rolling) is shown to yield a nanocomposite reinforced with dispersed intermetallic phases of different origins, namely Al9FeNi eutectic aluminides and MgZn2, Al2Mg3Zn3, and Al3Zr secondary phases. The results of uniaxial tensile testing demonstrate good mechanical properties of the composite (ultimate tensile strength of 640 MPa, tensile yield strength of 628 MPa, and elongation of 5%).

scholarly journals Evaluation of anisotropy of mechanical properties of carbon steel flat products

2020 ◽  
Vol 24 (5) ◽  
pp. 1007-1018
Author(s):  
Tatiana Osipok ◽  
◽  
Semen Zaides ◽  
Keyword(s):  
Mechanical Properties ◽  
Fracture Surface ◽  
Tensile Testing ◽  
Transverse Direction ◽  
Longitudinal Direction ◽  
Structural Heterogeneity ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Testing ◽  
Metallic Inclusions ◽  
Anisotropy Of Mechanical Properties

The purpose of the article is to establish experimentally the effect of material inhomogeneity on the characteristics of strength ( σ в, σ 0.2) and plasticity (δ) on example of a rolled steel sheet. Uniaxial tensile testing was carried out on flat samples of hot-rolled sheet made of St3 alloy cut in three directions relative to rolling: along, across and at the angle of 450. The heterogeneity of structure was established by studying the fracture surface of the destroyed samples after tensile testing. A metallographic research and micromechanical testing (measurement of microhardness) of sections parallel to the fracture surface were carried out as well. The uniaxial tensile testing of flat samples resulted in obtaining the values of the characteristics of strength ( σ в, σ 0.2) and plasticity (δ). The analysis of fracture patterns, microstructure and microhardness values of the material allowed to reveal the structural heterogeneity caused by the presence of fibrousness and a banded ferrite-pearlite structure oriented along the deformation direction. The formation reason of the latter was the presence of oriented non-metallic inclusions - elongated plastic sulfides. The study determined that the material under investigation features the anisotropy of mechanical properties and structural heterogeneity. The values of the ultimate strength ( σ в) and yield strength ( σ 0.2) decrease from the longitudinal direction to the transverse direction (relative to the rolling direction) and vice versa (from the transverse to longitudinal direction) in the first case probably due to the influence of non-metallic inclusions (plastic sulfides) and, as a result, the banded ferrite-pearlite structure; in the second case due to the influence of fiber direction. The values of the relative elongation (δ) decrease from the longitudinal direction to the direction at an angle of 450 and then increase to the transverse direction as a result of different hardening of the material during plastic deformation. This is proved by the obtained microhardness values of the investigated sections and the values of the maximum applied loads during the tensile test. The obtained values are obviously the result of the influence of fiber orientation relative to the existing maximum tensile stresses.

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