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GNPs改性环氧3D编织复合材料导热特性研究
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作者 徐焜 侯辰辉 +2 位作者 程云浦 钱小妹 严刚 《南京航空航天大学学报》 CAS CSCD 北大核心 2024年第4期705-711,共7页
石墨烯纳米片(Graphene nanoplatelets,GNPs)改性3D编织复合材料将GNPs与编织物有机融合,有望协同提高材料导热特性。然而,3D编织复合材料内胞和表胞呈现出不同的导热特性,加之GNPs的协同改性作用,增加了材料导热特性研究难度。本文紧扣... 石墨烯纳米片(Graphene nanoplatelets,GNPs)改性3D编织复合材料将GNPs与编织物有机融合,有望协同提高材料导热特性。然而,3D编织复合材料内胞和表胞呈现出不同的导热特性,加之GNPs的协同改性作用,增加了材料导热特性研究难度。本文紧扣GNPs改性3D编织复合材料细观结构特征,以GNPs改性树脂等效热导率表征为基础,基于周期性温度边界条件,构建材料的多胞有限元热物理分析模型,详尽研究了GNPs含量、编织角和纤维体积分数等对各胞元热导率的影响规律。分析表明:随着GNPs含量增加,3D编织复合材料导热特性逐步提升。随着编织角增加,GNPs改性3D编织复合材料横向热导率迅速增加而纵向热导率下降;同时,GNPs改性3D编织复合材料热导率随纤维体积分数增加而提升。上述规律为GNPs改性3D编织复合材料导热性能设计提供了坚实的理论基础。 展开更多
关键词 3D编织 热导率 石墨烯纳米片 胞元分析 有限建模
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考虑腹板弯曲的一维格栅夹层结构热变形 被引量:1
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作者 张锐 尚新春 《北京理工大学学报》 EI CAS CSCD 北大核心 2015年第4期331-335,共5页
针对温度载荷作用下一维格栅夹层结构的柱面弯曲问题,提出了一个新的考虑了腹板弯曲效应的分析模型.假设夹芯内变形后腹板依然垂直于上、下面板,并且腹板两端无相对转动.将腹板和面板均视为处于弯曲和热伸长状态下的弹性梁,由此建立了... 针对温度载荷作用下一维格栅夹层结构的柱面弯曲问题,提出了一个新的考虑了腹板弯曲效应的分析模型.假设夹芯内变形后腹板依然垂直于上、下面板,并且腹板两端无相对转动.将腹板和面板均视为处于弯曲和热伸长状态下的弹性梁,由此建立了所选胞元的平衡及几何方程,以及相邻胞元间受力和位移的相互关系.利用传递矩阵方法得到了夹层结构受热变形.作为一个算例,分析了几何与材料参数对悬臂夹层结构自由端最大挠度的影响.本文结果与有限元方法得到的结果相一致,证实了本文所提出的分析模型的正确性. 展开更多
关键词 格栅夹层结构 热变形 腹板弯曲 胞元分析 传递矩阵
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Relationship between the cytotoxin-associated gene-A status of H pylori strains and cerebral infarction in European Caucasians and Chinese Han: A meta-analysis 被引量:12
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作者 Shuo Zhang Yang Guo +1 位作者 Yan Ma Yue Teng 《World Journal of Gastroenterology》 SCIE CAS CSCD 2008年第8期1286-1292,共7页
AIM: To study the relationship between the cytotoxinassociated gene-A (CagA) status of H pylori strains and cerebral infarction among European Caucasians and Chinese Han by conducting a meta-analysis.METHODS: Ten ... AIM: To study the relationship between the cytotoxinassociated gene-A (CagA) status of H pylori strains and cerebral infarction among European Caucasians and Chinese Han by conducting a meta-analysis.METHODS: Ten case-control studies, with data on a total of 907 cases and 966 controls, were retrieved and considered; disqualified studies were excluded. The included studies were then tested for heterogeneity, and a meta-analysis was performed.RESULTS: The combined data revealed CagA-bearing strains of Hpylori which cause chronic infection are associated with an increased risk of cerebral infarction (OR = 2.66, 950 CI: 2.17-3.26), but no such relationship was found with CagA-negative strains (OR = 0.74, 95% CI: 0.49-1.10) in the overall population. We performed subgroup analyses, dividing the overall population into European Caucasians and Chinese Han subgroups, and analyzed the studies according to their subgroup classification. Through the subgroup analysis, an association between cerebral infarction and CagAbearing strains was found in both subgroups (OR = 2.60, 95% CI: 1.93-3.49 in Chinese Han; OR = 2.71, 95% CI: 2.05-3.59 in European Caucasians), but no significant association was found between cerebral infarction and CagA-negative strains (OR = 0.81, 95% CI: 0.45-1.48 in Chinese Han; OR = 0.64, 95% CI: 0.37-1.09 in European Caucasians).CONCLUSION: These results suggest CagA-bearing strains of H pylori are significantly associated with susceptibility to cerebral infarction in Chinese Han and European Caucasians, but that CagA-negative strains are not a definite predisposing factor in either subgroup. The magnitude of this association with cerebral infarction needs to be confirmed by prospective studies and combined studies of Hpylori eradication. 展开更多
关键词 Cytotoxin-associated gene-A H pylori Cerebral infarction META-ANALYSIS
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Relationship between red blood cell distribution width and intermediate-term mortality in elderly patients after percutaneous coronary intervention 被引量:7
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作者 Xin-Min LIU Chang-Sheng MA Xiao-Hui LIU Xin DU Jun-Ping KANG Yin ZHANG Jia-Hui WU 《Journal of Geriatric Cardiology》 SCIE CAS CSCD 2015年第1期17-22,共6页
Background Large-scale clinical research on the relationship between red blood cell distribution width (RDW) and intermediate-term prognosis in elderly patients with coronary artery disease (CAD) is lacking. Thus,... Background Large-scale clinical research on the relationship between red blood cell distribution width (RDW) and intermediate-term prognosis in elderly patients with coronary artery disease (CAD) is lacking. Thus, this study investigated the effects of RDW on the intermediate-term mortality of elderly patients who underwent elective percutaneous coronary intervention (PCI). Methods Data from 1891 patients 〉 65 years old underwent elective PCI from July 2009 to September 2011 were collected. Based on preoperative median RDW (12.3%), the patients were divided into two groups. The low RDW group (RDW 〈 12.3%) had 899 cases; the high RDW group (RDW 〉 12.3%) had 992 cases. The all-cause mortality rates of the two groups were compared. Results Patients in the high RDW group were more likely to be female and accompanied with diabetes, had lower hemoglobin level. The mean follow-up period was 527 days. During follow-up, 61 patients died (3.2%). The postoperative mortality of the high RDW group was significantly higher than that of the low RDW group (4.3% vs. 2.0%, P = 0.004). After adjusting other factors, multivariate Cox regression analysis revealed that preoperative high RDW was significantly associated with postoperative all-cause mortality (hazard ratio: 2.301, 95% confidence interval: 1.106-4.785, P = 0.026). Conclusions Increased RDW was an independent predictor of the increased intermediate-term all-cause mortality in elderly CAD patients after elective PCI. 展开更多
关键词 Coronary artery disease Elderly patients Percutaneous coronary intervention Red blood cell distribution width
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Synthesis Antimicrobial Activity of p-Dimetyl-Amino-Benyzlaldehide Shift Base of α-NaftyI-Amine and Metal Complexes
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作者 Aysel Rahimova Parvin Mamedova Mahizar Aliyeva Boyukhanim Aminova 《Journal of Chemistry and Chemical Engineering》 2014年第7期682-685,共4页
A new Shift bases was synthesized by the reaction of p-dimetyl-amino-benzylaldehide and α-naftyl-amine. All synthesized compounds were characterized by elemental analysis, IR (infra red) spectroscopy and NMR (nucl... A new Shift bases was synthesized by the reaction of p-dimetyl-amino-benzylaldehide and α-naftyl-amine. All synthesized compounds were characterized by elemental analysis, IR (infra red) spectroscopy and NMR (nuclear magnetic resonance) spectroscopy and evaluated for their in vitro antifungal activities of the compounds tested against Pseudomonas aeruginosa, Mycobacterium lacticolium, Aspergillus niger, Cladasporium resinale, Penicillium chrosegenum, Chastorniurn gloloodium and Trichoderma virideh. These derivatives have vast range of biological activities which benefit us. 展开更多
关键词 Shift bases antimicrobial activity metal complexes.
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Cell Area and Strut Distribution Changes of Bent Coronary Stents:A Finite Element Analysis
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作者 ZHAO Yang WU Wei +1 位作者 YANG Da-zhi QI Min 《Chinese Journal of Biomedical Engineering(English Edition)》 2009年第1期40-46,共7页
Coronary stents are metal coils or mesh tubes delivered to blocked vessels through catheters, whic Recently, special drugs h are expanded by balloons to reopen and scaffold target vessels. are carried by stents (drug... Coronary stents are metal coils or mesh tubes delivered to blocked vessels through catheters, whic Recently, special drugs h are expanded by balloons to reopen and scaffold target vessels. are carried by stents (drug-eluting stents) to further reduce instent restenosis rate after stenting procedure. However, continual study on biomechanical characteristics of stents is necessary provide a more suitable drug loading for better interactions between stents and tissue, or to platform for drug-eluting stents. The purpose of this paper is to show how finite element methods can be used to study cell area and strut distribution changes of bent coronary stents. A same bending deformation was applied to two commercial coronary stent models by a rigid curved vessel. Results show that the stent design influenced the changes of cell area and strut distribution under bending situation. The stent with links had more cell area changes at outer curvature, and the stent with peak-peak ( 〉 〈 ) strut design could have strut contact and overlapping at inner curvature. In conclusion, this finite element method can be used to study and compare cell area and strut distribution changes of bent stents, and to provide a convenient tool for designers in testing and improving biomechanical characteristics of new stents. 展开更多
关键词 coronary stents biomechanical characteristics cell area tissue prolapse strut distribution finite element methods
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格栅夹层梁的热弯曲变形 被引量:4
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作者 张锐 尚新春 《复合材料学报》 EI CAS CSCD 北大核心 2014年第6期1558-1565,共8页
考虑内部热传导,研究了格栅夹层梁一侧受热后的弯曲变形。认为变形后夹层结构中间腹板无弯曲。利用格栅夹层梁结构上的周期性,通过胞元结构的内力平衡方程和变形协调关系,得到了胞元两端内力和位移的关系。引入传递矩阵,建立了夹层梁内... 考虑内部热传导,研究了格栅夹层梁一侧受热后的弯曲变形。认为变形后夹层结构中间腹板无弯曲。利用格栅夹层梁结构上的周期性,通过胞元结构的内力平衡方程和变形协调关系,得到了胞元两端内力和位移的关系。引入传递矩阵,建立了夹层梁内力和变形随温度变化的表达式。应用所建立的模型计算了悬臂格栅夹层梁在其上表面受热后的变形。在格栅夹层梁包含的胞元数量较多、腹板高度较小且厚度与表板厚度相近的情况下,由本文模型计算得到的挠度结果与有限元结果吻合较好。 展开更多
关键词 格栅夹层结构 热弯曲 变形 结构分析 传递矩阵
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Finite element analysis of micropipette aspiration considering finite size and compressibility of cells
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作者 LI YongSheng CHEN WeiYi 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第11期2208-2215,共8页
Micropipette aspiration(MA) is widely applied in cell mechanics, however, at small deformations a common model corresponding to the MA is the half-space model wherein the finite cell size and cell compressibility are ... Micropipette aspiration(MA) is widely applied in cell mechanics, however, at small deformations a common model corresponding to the MA is the half-space model wherein the finite cell size and cell compressibility are neglected. This study extends the half-space model by accounting for the influence of cell geometry and compressibility(sphere model). Using a finite element analysis of cell aspiration into a micropipette, an elastic approximation formula of the aspirated length was derived for the sphere model. The approximation formula includes the geometry parameter of the sphere model(ζ = R/a, R is the radius of the cell, and a is the inner radius of the micropipette) and the Poisson's ratio v of the cell. The results indicate that the parameter and Poisson's ratio v markedly affect the aspirated length, particularly for small and v. When ζ→∞ and v→0.5,the approximation formula tends to the analytical solution for the half-space model. In the incompressible case(v = 0.5), within the general experimental range(ζ varying from 2 to 4), the difference between the analytical solution and the approximate one is significant, and is up to 29% of the approximation solution when ζ= 2. Additionally, parametere was introduced to evaluate the error of elastic moduli between the half-space model and sphere model. Based on the approximation formula, the ζ thresholds, beyond which e becomes larger than 10% and 20%, were derived. 展开更多
关键词 micropipette aspiration mechanical properties finite size COMPRESSIBILITY approximation formula
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