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Isogeometric Analysis of Hyperelastic Material Characteristics for Calcified Aortic Valve
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作者 Long Chen Ting Li +3 位作者 Liang Liu Wenshuo Wang xiaoxiao du Wei Wang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期2773-2806,共34页
This study explores the implementation of computed tomography(CT)reconstruction and simulation techniques for patient-specific valves,aiming to dissect the mechanical attributes of calcified valves within transcathete... This study explores the implementation of computed tomography(CT)reconstruction and simulation techniques for patient-specific valves,aiming to dissect the mechanical attributes of calcified valves within transcatheter heart valve replacement(TAVR)procedures.In order to facilitate this exploration,it derives pertinent formulas for 3D multi-material isogeometric hyperelastic analysis based on Hounsfield unit(HU)values,thereby unlocking foundational capabilities for isogeometric analysis in calcified aortic valves.A series of uniaxial and biaxial tensile tests is executed to obtain an accurate constitutive model for calcified active valves.To mitigate discretization errors,methodologies for reconstructing volumetric parametric models,integrating both geometric and material attributes,are introduced.Applying these analytical formulas,constitutive models,and precise analytical models to isogeometric analyses of calcified valves,the research ascertains their close alignment with experimental results through the close fit in displacement-stress curves,compellingly validating the accuracy and reliability of the method.This study presents a step-by-step approach to analyzing themechanical characteristics of patient-specific valves obtained fromCT images,holding significant clinical implications and assisting in the selection of treatment strategies and surgical intervention approaches in TAVR procedures. 展开更多
关键词 Calcified aortic valves tensile test constitutive relations CT reconstruction isogeometric hyperelastic analysis
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T-Splines Based Isogeometric Topology Optimization with Arbitrarily Shaped Design Domains 被引量:5
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作者 Gang Zhao Jiaming Yang +3 位作者 Wei Wang Yang Zhang xiaoxiao du Mayi Guo 《Computer Modeling in Engineering & Sciences》 SCIE EI 2020年第6期1033-1059,共27页
In this paper,a new isogeometric topology optimization(ITO)method is proposed by using T-splines based isogeometric analysis(IGA).The arbitrarily shaped design domains,directly obtained from CAD,are represented by a s... In this paper,a new isogeometric topology optimization(ITO)method is proposed by using T-splines based isogeometric analysis(IGA).The arbitrarily shaped design domains,directly obtained from CAD,are represented by a single T-spline surface which overcomes the topological limitations of Non-Uniform Rational B-Spline(NURBS).The coefficients correlated with control points are directly used as design variables.Therefore,the T-spline basis functions applied for geometry description and calculation of structural response are simultaneously introduced to represent the density distribution.Several numerical examples show that the proposed approach leads to a coherent workflow to handle design problems of complicated structures.The optimized results are free of checkerboard patterns without additional stabilization and filtering techniques due to the properties of T-splines,which also simplified the post-processing.In addition,through performing local refinement,we can easily achieve multiresolution optimization and infill optimization within the T-splines based framework.In general,the proposed method provides a possibility to design,analyze,and optimize engineering structures in a uniform model,which has the potential to improve design efficiency and reduce the cost of product development. 展开更多
关键词 Topology optimization isogeometric analysis unstructured T-splines Bézier extraction
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T-Splines for Isogeometric Analysis of Two-Dimensional Nonlinear Problems 被引量:3
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作者 Mayi Guo Gang Zhao +3 位作者 Wei Wang xiaoxiao du Ran Zhang Jiaming Yang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2020年第5期821-843,共23页
Nonlinear behaviors are commonplace in many complex engineering applications,e.g.,metal forming,vehicle crash test and so on.This paper focuses on the T-spline based isogeometric analysis of two-dimensional nonlinear ... Nonlinear behaviors are commonplace in many complex engineering applications,e.g.,metal forming,vehicle crash test and so on.This paper focuses on the T-spline based isogeometric analysis of two-dimensional nonlinear problems including general large deformation hyperelastic problems and small deformation elastoplastic problems,to reveal the advantages of local refinement property of T-splines in describing nonlinear behavior of materials.By applying the adaptive refinement capability of T-splines during the iteration process of analysis,the numerical simulation accuracy of the nonlinear model could be increased dramatically.The Bézier extraction of the T-splines provides an element structure for isogeometric analysis that can be easily incorporated into existing nonlinear finite element codes.In addition,T-splines show great superiority of modeling complex geometries especially when the model is irregular and with hole features.Several numerical examples have been tested to validate the accuracy and convergence of the proposed method.The obtained results are compared with those from NURBS-based isogeometric analysis and commercial software ABAQUS. 展开更多
关键词 Isogeometric analysis T-SPLINES NONLINEAR HYPERELASTICITY elastoplasticity adaptive refinement
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An efficient data structure for calculation of unstructured T-spline surfaces 被引量:2
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作者 Wei Wang Yang Zhang +1 位作者 xiaoxiao du Gang Zhao 《Visual Computing for Industry,Biomedicine,and Art》 2019年第1期7-15,共9页
To overcome the topological constraints of non-uniform rational B-splines,T-splines have been proposed to define the freeform surfaces.The introduction of T-junctions and extraordinary points makes it possible to repr... To overcome the topological constraints of non-uniform rational B-splines,T-splines have been proposed to define the freeform surfaces.The introduction of T-junctions and extraordinary points makes it possible to represent arbitrarily shaped models by a single T-spline surface.Whereas,the complexity and flexibility of topology structure bring difficulty in programming,which have caused a great obstacle for the development and application of T-spline technologies.So far,research literatures concerning T-spline data structures compatible with extraordinary points are very scarce.In this paper,an efficient data structure for calculation of unstructured T-spline surfaces is developed,by which any complex T-spline surface models can be easily and efficiently computed.Several unstructured T-spline surface models are calculated and visualized in our prototype system to verify the validity of the proposed method. 展开更多
关键词 T-SPLINES Non-uniform rational B-splines Unstructured T-mesh Extraordinary points
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Romidepsin(FK228) improves the survival of allogeneic skin grafts through downregulating the production of donor-specific antibody via suppressing the IRE1α-XBP1 pathway
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作者 Yuliang GUO Siyu SONG +5 位作者 xiaoxiao du Li TIAN Man ZHANG Hongmin ZHOU Zhonghua Klaus CHEN Sheng CHANG 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2022年第5期392-406,共15页
Antibody-mediated rejection(AMR)is one of the major causes of graft loss after transplantation.Recently,the regulation of B cell differentiation and the prevention of donor-specific antibody(DSA)production have gained... Antibody-mediated rejection(AMR)is one of the major causes of graft loss after transplantation.Recently,the regulation of B cell differentiation and the prevention of donor-specific antibody(DSA)production have gained increased attention in transplant research.Herein,we established a secondary allogeneic in vivo skin transplant model to study the effects of romidepsin(FK228)on DSA.The survival of grafted skins was monitored daily.The serum levels of DSA and the number of relevant immunocytes in the recipient spleens were evaluated by flow cytometry.Then,we isolated and purified B cells from B6mouse spleens in vitro by magnetic bead sorting.The B cells were cultured with interleukin-4(IL-4)and anti-clusters of differentiation 40(CD40)antibody with or without FK228 treatment.The immunoglobulin G1(IgG1)and IgM levels in the supernatant were evaluated by enzyme-linked immunosorbent assay(ELISA).Quantitative reverse transcription-polymerase chain reaction(RT-q PCR)and western blotting were conducted to determine the corresponding levels of messenger RNA(mRNA)and protein expression in cultured cells and the recipient spleens.The results showed that FK228 significantly improved the survival of allogeneic skin grafts.Moreover,FK228 inhibited DSA production in the serum along with the suppression of histone deacetylase 1(HADC1)and HDAC2 and the upregulation of the acetylation of histones H2A and H3.It also inhibited the differentiation of B cells to plasma cells,decreased the transcription of positive regulatory domain-containing 1(Prdm1)and X-box-binding protein 1(Xbp1),and decreased the expression of phosphorylated inositol-requiring enzyme 1α(p-IRE1α),XBP1,and B lymphocyte-induced maturation protein-1(Blimp-1).In conclusion,FK228 could decrease the production of antibodies by B cells via inhibition of the IRE1α-XBP1 signaling pathway.Thus,FK228 is considered as a promising therapeutic agent for the clinical treatment of AMR. 展开更多
关键词 Histone acetylation Romidepsin(FK228) Skin transplantation Donor-specific antibody Unfolded protein response
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妊娠期高血压并发急性肾损伤患者血清白细胞介素-22、硫化氢及护骨素水平的变化与意义
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作者 任国华 杜晓晓 +1 位作者 洪善玲 邵帅 《中华肾病研究电子杂志》 2023年第3期150-155,共6页
目的探究妊娠期高血压疾病(HDP)急性肾损伤(AKI)患者血清白细胞介素-22(IL-22)、硫化氢(H_(2)S)及护骨素(OPG)水平的变化与意义。方法选取2020年5月至2021年12月在本院产科就诊的50例无AKI并发症的HDP产妇为HDP组,50例HDP并发AKI的产妇... 目的探究妊娠期高血压疾病(HDP)急性肾损伤(AKI)患者血清白细胞介素-22(IL-22)、硫化氢(H_(2)S)及护骨素(OPG)水平的变化与意义。方法选取2020年5月至2021年12月在本院产科就诊的50例无AKI并发症的HDP产妇为HDP组,50例HDP并发AKI的产妇为HDP-AKI组,50例健康产妇为健康对照组。采用酶联免疫吸附(ELISA)测定IL-22、H_(2)S、OPG及血肌酐、尿素氮、尿蛋白水平。采用Pearson法分析IL-22、H_(2)S、OPG的相关性,Logistic回归分析筛选HDP-AKI产妇妊娠结局的影响因素。结果与健康对照组相比,HDP组患者血清中的IL-22、OPG及血肌酐、尿素氮、尿蛋白升高,H_(2)S降低(P<0.05)。与HDP组比较,HDP-AKI组患者血清中的IL-22、OPG及血肌酐、尿素氮、尿蛋白亦升高,H_(2)S降低(P<0.05)。在HDP-AKI组,IL-22与OPG呈正相关(r=0.386,P<0.001),而IL-22与H_(2)S呈负相关(r=-0.306,P<0.001),OPG亦与H_(2)S呈负相关(r=-0.312,P<0.001)。年龄、身体质量指数(BMI)、H_(2)S、IL-22、OPG、血肌酐、尿素氮、尿蛋白均是HDP合并AKI产妇妊娠结局的影响因素(P<0.05)。结论HDP合并AKI患者血清的IL-22、OPG水平增高、H_(2)S下降,可能会对妊娠结局产生一定的影响。 展开更多
关键词 妊娠期高血压疾病 急性肾损伤 白细胞介素-22 硫化氢 护骨素 妊娠结局
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