Antony S. K. Kho, Steve Béguin, E. O’Cearbhaill, A. N. Annaidh
Understanding of the mechanical properties of skin is crucial in evaluating the performance of skin-interfacing medical devices. Artificial skin models (ASMs) have rapidly gained attention as they are able to overcome the challenges in ethically sourcing consistent and representative ex vivo animal or human tissue models. Although some ASMs have become commercialised, a thorough understanding of the mechanical properties of the skin models is crucial to ensure that they are suitable for the purpose of the study. In the present study, skin and fat layers of ASMs (Simulab®, LifeLike®, SynDaver® and Parafilm®) were mechanically characterised through hardness, needle insertion, tensile and compression testing. Different boundary constraint conditions (minimally and highly constrained) were investigated for needle insertion testing, while anisotropic properties of the skin models were investigated through different specimen orientations during tensile testing. Analysis of variance (ANOVA) tests were performed to compare the mechanical properties between the skin models. Properties of the skin models were compared against literature to determine the suitability of the skin models based on the material property of interest. All skin models offer relatively consistent mechanical performance, providing a solid basis for benchtop evaluation of skin-interfacing medical device performance. Through prioritising models with mechanical properties that are consistent with human skin data, and with limited variance, researchers can use the data presented here as a toolbox to select the most appropriate ASM for their particular application.
{"title":"Mechanical characterisation of commercial artificial skin models.","authors":"Antony S. K. Kho, Steve Béguin, E. O’Cearbhaill, A. N. Annaidh","doi":"10.2139/ssrn.4378258","DOIUrl":"https://doi.org/10.2139/ssrn.4378258","url":null,"abstract":"Understanding of the mechanical properties of skin is crucial in evaluating the performance of skin-interfacing medical devices. Artificial skin models (ASMs) have rapidly gained attention as they are able to overcome the challenges in ethically sourcing consistent and representative ex vivo animal or human tissue models. Although some ASMs have become commercialised, a thorough understanding of the mechanical properties of the skin models is crucial to ensure that they are suitable for the purpose of the study. In the present study, skin and fat layers of ASMs (Simulab®, LifeLike®, SynDaver® and Parafilm®) were mechanically characterised through hardness, needle insertion, tensile and compression testing. Different boundary constraint conditions (minimally and highly constrained) were investigated for needle insertion testing, while anisotropic properties of the skin models were investigated through different specimen orientations during tensile testing. Analysis of variance (ANOVA) tests were performed to compare the mechanical properties between the skin models. Properties of the skin models were compared against literature to determine the suitability of the skin models based on the material property of interest. All skin models offer relatively consistent mechanical performance, providing a solid basis for benchtop evaluation of skin-interfacing medical device performance. Through prioritising models with mechanical properties that are consistent with human skin data, and with limited variance, researchers can use the data presented here as a toolbox to select the most appropriate ASM for their particular application.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"147 1","pages":"106090"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42559157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The scaffolds used for cardiac patches must mimic the viscoelastic behavior of the native tissue, which expands up to high deformation levels of its sedentary size during the systole segment of pumping blood. In our study, we exposed fabricated electrospun samples to repeated multistep tension by applying and removing deformation to mimic the mechanical behavior of helical fibered cardiac scaffolds. Since the fiber-based specimens exhibit viscoelastic behavior, the transient responses to constant deformation caused stress relaxation and stress recovery. However, these transient viscoelastic operations performed at high strain enable unpredictable phenomena, usually hidden behind stress softening and folding (plasticity) phenomena; the material significantly reduces the required stress, and remaining deformation occurs. Thus, by regulating the fabrication (electrospinning parameters) process and preconditioning before setting, the actual viscoelastic behavior of the electrospun scaffolds will be evident, as well as their limitations towards their application to cardiac patches development.
{"title":"Multistep deformation of helical fiber electrospun scaffold toward cardiac patches development.","authors":"A. Alattar, E. Gkouti, A. Czekanski","doi":"10.2139/ssrn.4340642","DOIUrl":"https://doi.org/10.2139/ssrn.4340642","url":null,"abstract":"The scaffolds used for cardiac patches must mimic the viscoelastic behavior of the native tissue, which expands up to high deformation levels of its sedentary size during the systole segment of pumping blood. In our study, we exposed fabricated electrospun samples to repeated multistep tension by applying and removing deformation to mimic the mechanical behavior of helical fibered cardiac scaffolds. Since the fiber-based specimens exhibit viscoelastic behavior, the transient responses to constant deformation caused stress relaxation and stress recovery. However, these transient viscoelastic operations performed at high strain enable unpredictable phenomena, usually hidden behind stress softening and folding (plasticity) phenomena; the material significantly reduces the required stress, and remaining deformation occurs. Thus, by regulating the fabrication (electrospinning parameters) process and preconditioning before setting, the actual viscoelastic behavior of the electrospun scaffolds will be evident, as well as their limitations towards their application to cardiac patches development.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"147 1","pages":"106157"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42096387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Laura Mendoza-Cerezo, J. Rodríguez-Rego, Anabel Soriano-Carrera, Alfonso C. Marcos-Romero, A. Macías-García
Tissue engineering is a continuously evolving field. One of the main lines of research in this field focuses on the replacement of bone defects with materials designed to interact with the cells of a living organism in order to provide the body with a structure on which new tissues can easily grow. Among the most commonly used materials are bioglasses, which are frequently used due to their versatility and good properties. This article discusses the results of the production of an injectable paste of Bioglass® 45S5 and hydroxyapatite on a 3D printed porous structure by additive manufacturing, using a thermoplastic (PLA). The results were evaluated in a specific application of the paste, so the mechanical and bioactive properties were studied to show the multiple possibilities of using this combination for its application in regenerative medicine and more specifically in bone implants.
{"title":"Fabrication and characterisation of bioglass and hydroxyapatite-filled scaffolds.","authors":"Laura Mendoza-Cerezo, J. Rodríguez-Rego, Anabel Soriano-Carrera, Alfonso C. Marcos-Romero, A. Macías-García","doi":"10.2139/ssrn.4388787","DOIUrl":"https://doi.org/10.2139/ssrn.4388787","url":null,"abstract":"Tissue engineering is a continuously evolving field. One of the main lines of research in this field focuses on the replacement of bone defects with materials designed to interact with the cells of a living organism in order to provide the body with a structure on which new tissues can easily grow. Among the most commonly used materials are bioglasses, which are frequently used due to their versatility and good properties. This article discusses the results of the production of an injectable paste of Bioglass® 45S5 and hydroxyapatite on a 3D printed porous structure by additive manufacturing, using a thermoplastic (PLA). The results were evaluated in a specific application of the paste, so the mechanical and bioactive properties were studied to show the multiple possibilities of using this combination for its application in regenerative medicine and more specifically in bone implants.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"144 1","pages":"105937"},"PeriodicalIF":0.0,"publicationDate":"2023-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42538234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Steglich, J. Besson, Inken Reinke, H. Helmholz, M. Luczak, V. Garamus, B. Wiese, D. Höche, C. Cyron, R. Willumeit-Römer
We propose a computational framework to study the effect of corrosion on the mechanical strength of magnesium (Mg) samples. Our work is motivated by the need to predict the residual strength of biomedical Mg implants after a given period of degradation in a physiological environment. To model corrosion, a mass-diffusion type model is used that accounts for localised corrosion using Weibull statistics. The overall mass loss is prescribed (e.g., based on experimental data). The mechanical behaviour of the Mg samples is modeled by a state-of-the-art Cazacu-Plunkett-Barlat plasticity model with a coupled damage model. This allowed us to study how Mg degradation in immersed samples reduces the mechanical strength over time. We performed a large number of in vitro corrosion experiments and mechanical tests to validate our computational framework. Our framework could predict both the experimentally observed loss of mechanical strength and the ductility due to corrosion for both tension and compression tests.
{"title":"Strength and ductility loss of Magnesium-Gadolinium due to corrosion in physiological environment: Experiments and modeling.","authors":"D. Steglich, J. Besson, Inken Reinke, H. Helmholz, M. Luczak, V. Garamus, B. Wiese, D. Höche, C. Cyron, R. Willumeit-Römer","doi":"10.2139/ssrn.4385334","DOIUrl":"https://doi.org/10.2139/ssrn.4385334","url":null,"abstract":"We propose a computational framework to study the effect of corrosion on the mechanical strength of magnesium (Mg) samples. Our work is motivated by the need to predict the residual strength of biomedical Mg implants after a given period of degradation in a physiological environment. To model corrosion, a mass-diffusion type model is used that accounts for localised corrosion using Weibull statistics. The overall mass loss is prescribed (e.g., based on experimental data). The mechanical behaviour of the Mg samples is modeled by a state-of-the-art Cazacu-Plunkett-Barlat plasticity model with a coupled damage model. This allowed us to study how Mg degradation in immersed samples reduces the mechanical strength over time. We performed a large number of in vitro corrosion experiments and mechanical tests to validate our computational framework. Our framework could predict both the experimentally observed loss of mechanical strength and the ductility due to corrosion for both tension and compression tests.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"144 1","pages":"105939"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43713158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Ankit, Frank Alifui-Segbaya, S. Hasanov, Alan R. White, K. E. Ahmed, Robert M. Love, I. Fidan
With global demand for 3D printed medical devices on the rise, the search for safer, inexpensive, and sustainable methods is timely. Herein, we assessed the practicality of the material extrusion process for acrylic denture bases of which successful outcomes can be extended to implant surgical guides, orthodontic splints, impression trays, record bases and obturators for cleft palates or other maxillary defects. Representative materials comprising denture prototypes and test samples were designed and built with in-house polymethylmethacrylate filaments using varying print directions (PDs), layer heights (LHs) and reinforcements (RFs) with short glass fiber. The study undertook a comprehensive evaluation of the materials to determine their flexural, fracture, and thermal properties. Additional analyses for tensile and compressive properties, chemical composition, residual monomer, and surface roughness (Ra) were completed for parts with optimum parameters. Micrographic analysis of the acrylic composites revealed adequate fiber-matrix compatibility and predictably, their mechanical properties improved simultaneously with RFs and decreased LHs. Fiber reinforcement also improved the overall thermal conductivity of the materials. Ra, on the other hand, improved visibly with decreased RFs and LHs and the prototypes were effortlessly polished and characterized with veneering composites to mimic gingival tissues. In terms of chemical stability, the residual methyl methacrylate monomer contents are well below standards threshold for biological reactions. Notably, 5 vol% acrylic composites built with 0.05 mm LH in 0° on z-axis produced optimum properties that are superior to those of conventional acrylic, milled acrylic and 3D printed photopolymers. Finite element modeling successfully replicated the tensile properties of the prototypes. It may well be argued that the material extrusion process is cost-effective; however, the speed of manufacturing could be longer than that of established methods. Although the mean Ra is within an acceptable range, mandatory manual finishing and aesthetic pigmentation are required for long-term intraoral use. At a proof-of-concept level, it is evident that the material extrusion process can be applied to build inexpensive, safe, and robust thermoplastic acrylic devices. The broad outcomes of this novel study are equally worthy of academic reflection, and further translation to the clinic.
随着全球对3D打印医疗设备的需求不断上升，寻找更安全、廉价和可持续的方法是及时的。在此，我们评估了丙烯酸义齿基托材料挤压工艺的实用性，其成功的结果可以扩展到种植手术导向、正畸夹板、印模托盘、记录基托和腭裂或其他上颌缺陷的闭孔器。采用不同的打印方向(pd)、层高(LHs)和短玻璃纤维增强(RFs)，用内部聚甲基丙烯酸甲酯长丝设计和构建具有代表性的材料，包括义齿原型和测试样品。该研究对材料进行了全面的评估，以确定其弯曲、断裂和热性能。对于具有最佳参数的部件，完成了拉伸和压缩性能、化学成分、残留单体和表面粗糙度(Ra)的附加分析。显微分析表明，复合材料具有良好的纤维-基体相容性，其力学性能随着RFs和LHs的降低而提高。纤维增强也提高了材料的整体导热性。另一方面，Ra随着RFs和LHs的降低而明显改善，并且原型可以毫不费力地抛光并使用贴面复合材料模拟牙龈组织。在化学稳定性方面，残留的甲基丙烯酸甲酯单体含量远低于生物反应的标准阈值。值得注意的是，在z轴0°方向上以0.05 mm LH构建的5 vol%丙烯酸复合材料的性能优于传统丙烯酸、研磨丙烯酸和3D打印光聚合物。有限元模型成功地复制了原型的拉伸性能。可以很好地争辩说，材料挤压工艺是具有成本效益的;然而，制造的速度可能比现有方法要长。虽然平均Ra在可接受范围内，但长期口内使用仍需要强制手工精加工和美观色素沉着。在概念验证层面，很明显，材料挤压工艺可以应用于构建廉价、安全、坚固的热塑性丙烯酸装置。这项新研究的广泛结果同样值得学术反思，并进一步转化为临床。
{"title":"Material extrusion of thermoplastic acrylic for intraoral devices: Technical feasibility and evaluation.","authors":"G. Ankit, Frank Alifui-Segbaya, S. Hasanov, Alan R. White, K. E. Ahmed, Robert M. Love, I. Fidan","doi":"10.2139/ssrn.4354976","DOIUrl":"https://doi.org/10.2139/ssrn.4354976","url":null,"abstract":"With global demand for 3D printed medical devices on the rise, the search for safer, inexpensive, and sustainable methods is timely. Herein, we assessed the practicality of the material extrusion process for acrylic denture bases of which successful outcomes can be extended to implant surgical guides, orthodontic splints, impression trays, record bases and obturators for cleft palates or other maxillary defects. Representative materials comprising denture prototypes and test samples were designed and built with in-house polymethylmethacrylate filaments using varying print directions (PDs), layer heights (LHs) and reinforcements (RFs) with short glass fiber. The study undertook a comprehensive evaluation of the materials to determine their flexural, fracture, and thermal properties. Additional analyses for tensile and compressive properties, chemical composition, residual monomer, and surface roughness (Ra) were completed for parts with optimum parameters. Micrographic analysis of the acrylic composites revealed adequate fiber-matrix compatibility and predictably, their mechanical properties improved simultaneously with RFs and decreased LHs. Fiber reinforcement also improved the overall thermal conductivity of the materials. Ra, on the other hand, improved visibly with decreased RFs and LHs and the prototypes were effortlessly polished and characterized with veneering composites to mimic gingival tissues. In terms of chemical stability, the residual methyl methacrylate monomer contents are well below standards threshold for biological reactions. Notably, 5 vol% acrylic composites built with 0.05 mm LH in 0° on z-axis produced optimum properties that are superior to those of conventional acrylic, milled acrylic and 3D printed photopolymers. Finite element modeling successfully replicated the tensile properties of the prototypes. It may well be argued that the material extrusion process is cost-effective; however, the speed of manufacturing could be longer than that of established methods. Although the mean Ra is within an acceptable range, mandatory manual finishing and aesthetic pigmentation are required for long-term intraoral use. At a proof-of-concept level, it is evident that the material extrusion process can be applied to build inexpensive, safe, and robust thermoplastic acrylic devices. The broad outcomes of this novel study are equally worthy of academic reflection, and further translation to the clinic.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"143 1","pages":"105950"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47299822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rojee Oh, Jung-Hwa Lim, Chanhyeon Lee, Keun-Woo Lee, Sungyong Kim, Jong-Eun Kim
The use of digital manufacturing, particularly additive manufacturing using three-dimensional (3D) printing, is expanding in the field of dentistry. 3D-printed resin appliances must undergo an essential process, post-washing, to remove residual monomers; however, the effect of the washing solution temperature on the biocompatibility and mechanical properties remains unclear. Therefore, we processed 3D-printed resin samples under different post-washing temperatures (without temperature control (N/T), 30 °C, 40 °C, and 50 °C) for different durations (5, 10, 15, 30, and 60 min) and evaluated the degree of conversion rate, cell viability, flexural strength, and Vickers hardness. Increasing the washing solution temperature significantly improved the degree of conversion rate and cell viability. Conversely, increasing the solution temperature and time decreased the flexural strength and microhardness. This study confirmed that the washing temperature and time influence the mechanical and biological properties of the 3D-printed resin. Washing 3D-printed resin at 30 °C for 30 min was most efficient to maintain optimal biocompatibility and minimize changes of mechanical properties.
{"title":"Effects of washing solution temperature on the biocompatibility and mechanical properties of 3D-Printed dental resin material.","authors":"Rojee Oh, Jung-Hwa Lim, Chanhyeon Lee, Keun-Woo Lee, Sungyong Kim, Jong-Eun Kim","doi":"10.2139/ssrn.4388792","DOIUrl":"https://doi.org/10.2139/ssrn.4388792","url":null,"abstract":"The use of digital manufacturing, particularly additive manufacturing using three-dimensional (3D) printing, is expanding in the field of dentistry. 3D-printed resin appliances must undergo an essential process, post-washing, to remove residual monomers; however, the effect of the washing solution temperature on the biocompatibility and mechanical properties remains unclear. Therefore, we processed 3D-printed resin samples under different post-washing temperatures (without temperature control (N/T), 30 °C, 40 °C, and 50 °C) for different durations (5, 10, 15, 30, and 60 min) and evaluated the degree of conversion rate, cell viability, flexural strength, and Vickers hardness. Increasing the washing solution temperature significantly improved the degree of conversion rate and cell viability. Conversely, increasing the solution temperature and time decreased the flexural strength and microhardness. This study confirmed that the washing temperature and time influence the mechanical and biological properties of the 3D-printed resin. Washing 3D-printed resin at 30 °C for 30 min was most efficient to maintain optimal biocompatibility and minimize changes of mechanical properties.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"143 1","pages":"105906"},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46103480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. H. Da Silva, Laura Ajamil Rinaldi, D. Lazar, V. Ussui, R. Tango, R. Belli, U. Lohbauer, P. Cesar
Y-TZP/MWCNT-SiO2 nanocomposite was synthesized by co-precipitation and hydrothermal treatment methods. After the characterization of the MWCNT-SiO2 powder, specimens were obtained from the synthesized material Y-TZP/MWCNT-SiO2 by uniaxial pressing for a second characterization and later comparison of its optical and mechanical properties with the conventional Y-TZP. The MWCNT-SiO2 was presented in bundles of carbon nanotubes coated by silica (mean length: 5.10 ± 1.34 μm /D90: 6.9 μm). The composite manufactured was opaque (contrast ratio: 0.9929 ± 0.0012) and had a white color with a slightly difference from the conventional Y-TZP (ΔE00: 4.4 ± 2.2) color. The mechanical properties of Y-TZP/MWCNT-SiO2: vickers hardness (10.14 ± 1.27 GPa; p = 0.25) and fracture toughness (4.98 ± 0.30 MPa m1/2; p = 0.39), showed no significant difference from the conventional Y-TZP (hardness: 8.87 ± 0.89; fracture toughness: 4.98 ± 0.30 MPa m1/2). However, for flexural strength (p = 0.003), a lower value was obtained for Y-TZP/MWCNT-SiO2 (299.4 ± 30.5 MPa) when compared to the control Y-TZP (623.7 ± 108.8 MPa). The manufactured Y-TZP/MWCNT-SiO2 composite presented satisfactory optical properties, however the co-precipitation and hydrothermal treatment methods need to be optimized to avoid the formation of porosities and strong agglomerates, both from Y-TZP particles and MWCNT-SiO2 bundles, which lead to a significant decrease in the material flexural strength.
{"title":"Development of Y-TZP/MWCNT-SiO2 nanocomposite for dental protheses.","authors":"L. H. Da Silva, Laura Ajamil Rinaldi, D. Lazar, V. Ussui, R. Tango, R. Belli, U. Lohbauer, P. Cesar","doi":"10.2139/ssrn.4388790","DOIUrl":"https://doi.org/10.2139/ssrn.4388790","url":null,"abstract":"Y-TZP/MWCNT-SiO2 nanocomposite was synthesized by co-precipitation and hydrothermal treatment methods. After the characterization of the MWCNT-SiO2 powder, specimens were obtained from the synthesized material Y-TZP/MWCNT-SiO2 by uniaxial pressing for a second characterization and later comparison of its optical and mechanical properties with the conventional Y-TZP. The MWCNT-SiO2 was presented in bundles of carbon nanotubes coated by silica (mean length: 5.10 ± 1.34 μm /D90: 6.9 μm). The composite manufactured was opaque (contrast ratio: 0.9929 ± 0.0012) and had a white color with a slightly difference from the conventional Y-TZP (ΔE00: 4.4 ± 2.2) color. The mechanical properties of Y-TZP/MWCNT-SiO2: vickers hardness (10.14 ± 1.27 GPa; p = 0.25) and fracture toughness (4.98 ± 0.30 MPa m1/2; p = 0.39), showed no significant difference from the conventional Y-TZP (hardness: 8.87 ± 0.89; fracture toughness: 4.98 ± 0.30 MPa m1/2). However, for flexural strength (p = 0.003), a lower value was obtained for Y-TZP/MWCNT-SiO2 (299.4 ± 30.5 MPa) when compared to the control Y-TZP (623.7 ± 108.8 MPa). The manufactured Y-TZP/MWCNT-SiO2 composite presented satisfactory optical properties, however the co-precipitation and hydrothermal treatment methods need to be optimized to avoid the formation of porosities and strong agglomerates, both from Y-TZP particles and MWCNT-SiO2 bundles, which lead to a significant decrease in the material flexural strength.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"143 1","pages":"105888"},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45096493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The cervix is a soft tissue exhibiting time-dependent behavior under mechanical loads. The cervix is a vital mechanical barrier to protect the growing fetus. The remodeling of the cervical tissue, characterized by an increase in time-dependent material properties, is necessary for a safe parturition. The failure of its mechanical function and accelerated tissue remodeling is hypothesized to lead to preterm birth, which is birth before 37 weeks of gestation. To understand the mechanism of the time-dependent behavior of the cervix under compressive states, we employ a porous-viscoelastic material model to describe a set of spherical indentation tests performed on nonpregnant and term pregnant tissue. A genetic algorithm-based inverse finite element analysis is used to fit the force-relaxation data by optimizing the material parameters, and the statistical analysis of the optimized material parameters is conducted on different sample groups. The force response is captured well using the porous-viscoelastic model. The indentation force-relaxation of the cervix is explained by the porous effects and the intrinsic viscoelastic properties of the extracellular matrix (ECM) microstructure. The hydraulic permeability obtained from the inverse finite element analysis agrees with the trend of the value directly measured previously by our group. The nonpregnant samples are found significantly more permeable than the pregnant samples. Within nonpregnant samples, the posterior internal os is found significantly less permeable than the anterior and posterior external os. The proposed model exhibits the superior capability to capture the force-relaxation response of the cervix under indentation, as compared to the conventional quasi-linear viscoelastic framework (range of r2 of the porous-viscoelastic model 0.88-0.98 vs. quasi-linear model: 0.67-0.89). As a constitutive model with a relatively simple form, the porous-viscoelastic framework has the potential to be used to understand disease mechanisms of premature cervical remodeling, model contact of the cervix with biomedical devices, and interpret force readings from novel in-vivo measurement tools such as an aspiration device.
{"title":"A finite porous-viscoelastic model capturing mechanical behavior of human cervix under multi-step spherical indentation.","authors":"Lei Shi, K. Myers","doi":"10.2139/ssrn.4348162","DOIUrl":"https://doi.org/10.2139/ssrn.4348162","url":null,"abstract":"The cervix is a soft tissue exhibiting time-dependent behavior under mechanical loads. The cervix is a vital mechanical barrier to protect the growing fetus. The remodeling of the cervical tissue, characterized by an increase in time-dependent material properties, is necessary for a safe parturition. The failure of its mechanical function and accelerated tissue remodeling is hypothesized to lead to preterm birth, which is birth before 37 weeks of gestation. To understand the mechanism of the time-dependent behavior of the cervix under compressive states, we employ a porous-viscoelastic material model to describe a set of spherical indentation tests performed on nonpregnant and term pregnant tissue. A genetic algorithm-based inverse finite element analysis is used to fit the force-relaxation data by optimizing the material parameters, and the statistical analysis of the optimized material parameters is conducted on different sample groups. The force response is captured well using the porous-viscoelastic model. The indentation force-relaxation of the cervix is explained by the porous effects and the intrinsic viscoelastic properties of the extracellular matrix (ECM) microstructure. The hydraulic permeability obtained from the inverse finite element analysis agrees with the trend of the value directly measured previously by our group. The nonpregnant samples are found significantly more permeable than the pregnant samples. Within nonpregnant samples, the posterior internal os is found significantly less permeable than the anterior and posterior external os. The proposed model exhibits the superior capability to capture the force-relaxation response of the cervix under indentation, as compared to the conventional quasi-linear viscoelastic framework (range of r2 of the porous-viscoelastic model 0.88-0.98 vs. quasi-linear model: 0.67-0.89). As a constitutive model with a relatively simple form, the porous-viscoelastic framework has the potential to be used to understand disease mechanisms of premature cervical remodeling, model contact of the cervix with biomedical devices, and interpret force readings from novel in-vivo measurement tools such as an aspiration device.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"143 1","pages":"105875"},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48954781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Isabella Caruso, Kaiyang Yin, P. Divakar, U. Wegst
Tensile properties of directionally freeze-cast biopolymer scaffolds are rarely reported, even though they are of interest from a fundamental science perspective and critical in applications such as scaffolds for the regeneration of nerves or when used as ureteral stents. The focus of this study is on collagen scaffolds freeze-cast with two different applied cooling rates (10 °C/min and 1 °C/min) in two freezing directions (longitudinal and radial). Reported are the results of a systematic structural characterization of dry scaffolds by scanning electron microscopy and the mechanical characterization in tension of both dry and fully hydrated scaffolds. Systematic structure-property-processing correlations are obtained for a comparison of the tensile performance of longitudinally and radially freeze-cast collagen scaffolds with their performance in compression. Collated, the correlations, obtained both in tension in this study and in compression for collagen and chitosan in two earlier reports, not only enable the custom-design of freeze-cast biopolymer scaffolds for biomedical applications but also provide new insights into similarities and differences of scaffold and cell-wall structure formation during the directional solidification of "smooth" and "fibrillar" biopolymers.
{"title":"Tensile properties of freeze-cast collagen scaffolds: How processing conditions affect structure and performance in the dry and fully hydrated states.","authors":"Isabella Caruso, Kaiyang Yin, P. Divakar, U. Wegst","doi":"10.2139/ssrn.4340647","DOIUrl":"https://doi.org/10.2139/ssrn.4340647","url":null,"abstract":"Tensile properties of directionally freeze-cast biopolymer scaffolds are rarely reported, even though they are of interest from a fundamental science perspective and critical in applications such as scaffolds for the regeneration of nerves or when used as ureteral stents. The focus of this study is on collagen scaffolds freeze-cast with two different applied cooling rates (10 °C/min and 1 °C/min) in two freezing directions (longitudinal and radial). Reported are the results of a systematic structural characterization of dry scaffolds by scanning electron microscopy and the mechanical characterization in tension of both dry and fully hydrated scaffolds. Systematic structure-property-processing correlations are obtained for a comparison of the tensile performance of longitudinally and radially freeze-cast collagen scaffolds with their performance in compression. Collated, the correlations, obtained both in tension in this study and in compression for collagen and chitosan in two earlier reports, not only enable the custom-design of freeze-cast biopolymer scaffolds for biomedical applications but also provide new insights into similarities and differences of scaffold and cell-wall structure formation during the directional solidification of \"smooth\" and \"fibrillar\" biopolymers.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"144 1","pages":"105897"},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46201433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ability of the urinary bladder to perform its physiological function depends largely on its mechanical characteristics. Understanding the mechanics of this tissue is crucial to the development of accurate models of not just this specific organ, but of the pelvic floor overall. In this study, we tested porcine bladder to identify variations in the tissue's viscoelastic characteristics associated with anatomical locations and swelling. We investigated this relationship using a series of stress-relaxation experiments as well as a modified Maxwell-Wiechert model to aid in the interpretation of the experimental data. Our results highlight that tissue located near the neck of the bladder presents significantly different viscoelastic characteristics than the body of the organ. This supports what was previously observed and is a valuable contribution to the understanding of the location-specific properties of the bladder. We also tested the effect of swelling, revealing that the bladder's viscoelastic behavior is mostly independent of solution osmolarity in hypoosmotic solutions, but the use of a hyperosmotic solution can significantly affect its behavior. This is significant, since several urinary tract pathologies can lead to chronic inflammation and disrupt the urothelial barrier causing increased urothelial permeability, thus subjecting the bladder wall to non-physiologic osmotic challenge.
{"title":"Effects of swelling and anatomical location on the viscoelastic behavior of the porcine urinary bladder wall.","authors":"Tyler G. Tuttle, D. McClintock, S. Roccabianca","doi":"10.2139/ssrn.4326307","DOIUrl":"https://doi.org/10.2139/ssrn.4326307","url":null,"abstract":"The ability of the urinary bladder to perform its physiological function depends largely on its mechanical characteristics. Understanding the mechanics of this tissue is crucial to the development of accurate models of not just this specific organ, but of the pelvic floor overall. In this study, we tested porcine bladder to identify variations in the tissue's viscoelastic characteristics associated with anatomical locations and swelling. We investigated this relationship using a series of stress-relaxation experiments as well as a modified Maxwell-Wiechert model to aid in the interpretation of the experimental data. Our results highlight that tissue located near the neck of the bladder presents significantly different viscoelastic characteristics than the body of the organ. This supports what was previously observed and is a valuable contribution to the understanding of the location-specific properties of the bladder. We also tested the effect of swelling, revealing that the bladder's viscoelastic behavior is mostly independent of solution osmolarity in hypoosmotic solutions, but the use of a hyperosmotic solution can significantly affect its behavior. This is significant, since several urinary tract pathologies can lead to chronic inflammation and disrupt the urothelial barrier causing increased urothelial permeability, thus subjecting the bladder wall to non-physiologic osmotic challenge.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"143 1","pages":"105926"},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45092487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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