“…Radial stiffness indicates intrinsic recoil of stents expanding their initial diameter when implanted in the lumen 22,30 . In order to evaluate the effect of runners on the radial compression performance of PLLA braided stents, the radial stiffness change was compared among stents with runners in Figure 4A,B.…”
Section: Resultsmentioning
confidence: 99%
“…Radial stiffness indicates intrinsic recoil of stents expanding their initial diameter when implanted in the lumen. 22,30 In order to evaluate the effect of runners on the radial compression performance of PLLA braided stents, the radial stiffness change was compared among stents with runners in Figure 4A,B. intersection between the axial runners and monofilaments is released, then relative sliding becomes dynamic friction, which lead to the radial force to decrease at a faster rate.…”
Section: Radial Compression Performance Of Braided Stentmentioning
confidence: 99%
“…For evaluating the mechanical performance of PLLA braided stents, studies have shown that the combination of radial performance and bending performance is more effective than using radial performance or bending performance alone, and it is also easier to understand the clinical significance of the PLLA braided stents. 29,30,32,33 As shown in Figure 5A, it shows the distribution diagram of the relationship between the radial performance and the bending performance of S1-1, S2-J1, S3-L1 and S4-Z1, and the stents are divided into three typical categories according to the relationship between the radial performance and the bending performance. C1-1 represents the PLLA braided stents with low radial performance and high bending performance.…”
Section: Evaluation Of Comprehensive Mechanical Performance For the Braided Stentsmentioning
Poly (L-lactic acid) (PLLA) braided stent is expected to treat the peripheral vascular and biliary obstructive diseases with its excellent biocompatibility and biodegradability. However, the application of PLLA is still restricted by insufficient mechanical performance. In this paper, a series of PLLA braided stents with runners in axial, circumferential and spiral directions were prepared, and the effects of the runners on the mechanical performance of PLLA braided stents were studied. Meanwhile, the relationship between radial supporting performance and bending performance was analyzed to evaluate the effects on mechanical performance of PLLA stents.According to the relationship, it is found that the runners in different directions have a great influence on the mechanical performance of the stents. Especially the runners in spiral direction can effectively improve the radial force and bending stiffness of the stents compared with the control group. This work provides some suggestions for the development and design of PLLA braided stents in the future.
“…Radial stiffness indicates intrinsic recoil of stents expanding their initial diameter when implanted in the lumen 22,30 . In order to evaluate the effect of runners on the radial compression performance of PLLA braided stents, the radial stiffness change was compared among stents with runners in Figure 4A,B.…”
Section: Resultsmentioning
confidence: 99%
“…Radial stiffness indicates intrinsic recoil of stents expanding their initial diameter when implanted in the lumen. 22,30 In order to evaluate the effect of runners on the radial compression performance of PLLA braided stents, the radial stiffness change was compared among stents with runners in Figure 4A,B. intersection between the axial runners and monofilaments is released, then relative sliding becomes dynamic friction, which lead to the radial force to decrease at a faster rate.…”
Section: Radial Compression Performance Of Braided Stentmentioning
confidence: 99%
“…For evaluating the mechanical performance of PLLA braided stents, studies have shown that the combination of radial performance and bending performance is more effective than using radial performance or bending performance alone, and it is also easier to understand the clinical significance of the PLLA braided stents. 29,30,32,33 As shown in Figure 5A, it shows the distribution diagram of the relationship between the radial performance and the bending performance of S1-1, S2-J1, S3-L1 and S4-Z1, and the stents are divided into three typical categories according to the relationship between the radial performance and the bending performance. C1-1 represents the PLLA braided stents with low radial performance and high bending performance.…”
Section: Evaluation Of Comprehensive Mechanical Performance For the Braided Stentsmentioning
Poly (L-lactic acid) (PLLA) braided stent is expected to treat the peripheral vascular and biliary obstructive diseases with its excellent biocompatibility and biodegradability. However, the application of PLLA is still restricted by insufficient mechanical performance. In this paper, a series of PLLA braided stents with runners in axial, circumferential and spiral directions were prepared, and the effects of the runners on the mechanical performance of PLLA braided stents were studied. Meanwhile, the relationship between radial supporting performance and bending performance was analyzed to evaluate the effects on mechanical performance of PLLA stents.According to the relationship, it is found that the runners in different directions have a great influence on the mechanical performance of the stents. Especially the runners in spiral direction can effectively improve the radial force and bending stiffness of the stents compared with the control group. This work provides some suggestions for the development and design of PLLA braided stents in the future.
“…With the improvement of magnesium alloy processing technology, the preparation of high-performance magnesium wires, plates, and other mini-size materials has been increasingly mature. There has been an up-surge interest in the potential use of Mg alloys for gastrointestinal surgery, such as the biliary stent [ 6 ], the hemostatic clip [ 7 ], and the anastomotic staple [ [8] , [9] , [10] , [11] , [12] ] and ring [ 13 ].…”
Section: Introductionmentioning
confidence: 99%
“…In the small intestine, the range of pH is approximately 5.0–7.7, and intestinal juice contains much pancreatin and buffer solution which can neutralize gastric acid for protecting intestinal mucosa from strong acid attack [ 14 , 20 , 21 ]. To date, even though numerous efforts based on the actual physiological environments of certain implantation sites have been devoted to evaluating the in vitro corrosion behavior of Mg [ 6 , [23] , [24] , [25] ], reports regarding the degradation of Mg alloys in gastric and intestinal fluids are relatively limited. Fig.…”
With an upsurge of biodegradable metal implants, the research and application of Mg alloys in the gastrointestinal environment of the digestive tract have been of great interest. Digestive enzymes, mainly pepsin in the stomach and pancreatin in the small intestine, are widespread in the gastrointestinal tract, but their effect on the degradation of Mg alloys has not been well understood. In this study, we investigated the impacts of pepsin and pancreatin on the degradation of Mg-2Zn alloy wires. The results showed that the pepsin and pancreatin had completely different even the opposite effects on the degradation of Mg, although they both affected the degradation product layer. The degradation rate of Mg wire declined with the addition of pepsin in simulated gastric fluid (SGF) but rose with the addition of pancreatin in simulated intestinal fluid (SIF). The opposite trends in degradation rate also resulted in completely different degradation morphologies in wires surface, where the pitting corrosion in SGF was inhibited because of the physical barrier effect of pepsin adsorption. In contrast, the adsorption of pancreatin affected the integrity of magnesium hydrogen phosphate film, causing a relatively uneven degraded surface. These results may help us to understand the role of different digestive enzymes in the degradation of magnesium and facilitate the development and clinical application of magnesium alloy implanted devices for the digestive tract.
This paper designs a strategy of introducing ultrafine precipitates into single‐phase microstructure to enhance Mg‐6Zn alloy wire. Three combined processes including equal channel angular pressing (ECAP), direct extrusion, and multi‐pass drawing are used to produce 0.3mm diameter wire. The results show that an isothermal process of ECAP, extrusion, and drawing at 320°C (named route B) produces a near fully solid solution microstructure and causes a very high elongation of 21% as well as an ultimate tensile strength of 24MPa. Furthermore, on this basis, the addition of an aging treatment before drawing induces the precipitation of the GP zone in the near single‐phase Mg matrix and improves the tensile elongation to 28%, and the ultimate tensile strength also is increased to 290MPa.This article is protected by copyright. All rights reserved.
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