教学课程资源库 更多>>

关键词： Finite element method  

摘要： The finite element approach is used for the first time to simulate and examine the free oscillation and transient response of a visco-elastic multi-directional functionally graded porous (MFGP) skew-nanoplate, taking into account surface effects using nonlocal strain gradient hypothesis. The mechanical characteristics of the materials vary in all three directions of length, width, and thickness of the plate according to the exponential law. Additionally, it has viscoelastic behavior according to the Kelvin-Voigt model. The novelty of this paper lies in the incorporation of the spatial variability of nonlocal and length-scale factors as additional mechanical characteristics of the material. The overall equation of motion for the plate is derived by including the classical plate hypothesis and Hamilton’s principle. A quadrilateral plate element with four nodes and six degrees of freedom is created using a non-conforming C2-level Hermitian function. This function offers precise results and rapid convergence for various forms and boundary conditions (BCs) that low-order elements cannot accomplish. The Newmark-beta direct integration technique is used to calculate the transient responses of the visco-elastic MFGP skew-nanoplate under various BCs. Furthermore, a thorough assessment of the impacts of several factors such as residual surface stress, grading indices, elastic foundation stiffness, skew angle, other geometrical parameters, and BCs on the transient responses of the viscoelastic MFGP skew-nanoplate has been uncovered. © The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag GmbH Germany, part of Springer Nature 2025.

关键词： Lamb waves   Topological insulators   Topological edge states   Topological corner states   Magnetic field modulation  

摘要： Recently, the concept of higher-order topological insulators has aroused widespread attention and research interest. However, current studies have predominantly focused on the domain of acoustic waves. Compared to acoustic waves, elastic waves are vector waves, making their study more complex and challenging. Therefore, achieving higher-order topological states in elastic waves holds significant research value. In this paper, we proposed the design of an intelligent topological metamaterial, which is composed of magneto-rheological thin layers and an elastic substrate. First, by adjusting the topological structure, we successfully excited first-order topological states of Lamb waves in numerical simulations. Subsequently, we constructed a two-dimensional topological structure to excite zero-order topological corner states. Given the unique advantages of magnetic fields in regulating material properties and behaviors, we investigated the effects of magnetic fields as an external control mechanism on Lamb waves in magneto-rheological materials. Our analysis focused on the regulation of Lamb wave topological edge states and corner states via magnetic fields. The results demonstrate that by varying the magnetic field strength, we can precisely control the characteristics of the topological states. Magnetic field modulation of the topological states in Lamb waves enables the realization of non-contact, controllable phononic devices, which is of great significance for the development of topological acoustics.

关键词： Neurodegenerative diseases  

摘要： The mechanical microenvironment plays a critical role in regulating brain development, injury repair, and the progression of neurodegenerative diseases. Despite extensive research on extracellular matrix stiffness, the effects of matrix viscoelasticity on neural cells, particularly in the context of brain injury and glial scar formation, remain elusive. In this study, we demonstrated, using an in vivo brain injury model, that matrix viscoelasticity, specifically the loss tangent, significantly increases during glial scar formation, which subsequently alters astrocyte behavior, leading to enhanced spreading and activation of reactive phenotypes. By employing an in vitro polyacrylamide hydrogel model that decouples viscosities from viscoelasticity, we reveal that microtubule dynamics, rather than actomyosin contractility, predominantly drive astrocyte responses within a viscoelastic microenvironment. These findings provide a deeper understanding of the mechanobiology of brain injuries and suggest that modulating matrix viscoelasticity could pave the way for novel mechanotherapeutic strategies to treat brain injuries and neurodegenerative diseases. (Figure presented.) © The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag GmbH Germany, part of Springer Nature 2025.

关键词： 锁骨中段骨折   钛制弹性髓内钉   三维移位   危险因素   相关性分析   工程化骨材料  

摘要： 背景:钛制弹性髓内钉植入治疗移位明显的锁骨中段骨折具有微创、弹性固定等特点,骨折的移位与后期功能密切相关,但对术前及钛制弹性髓内钉等髓内固定后断端三维移位分析的研究较少见。目的:探讨锁骨中段骨折后以及钛制弹性髓内钉固定后断端三维移位情况,并分析其危险因素。方法:选择2019年4月至2024年4月山东省文登整骨医院收治的锁骨中段骨折(断端短缩≥15 mm)患者91例,其中男57例、女34例,年龄(51.73±10.21)岁,均接受闭合复位钛制弹性髓内钉内固定治疗,术前及术后第1天均进行患侧锁骨CT扫描,将CT资料导入Mimics软件建模,测量并记录手术前后锁骨的长度、断端侧方移位及骨折远端沿X、Y、Z轴旋转情况。利用Pearson相关系数进行各参数相关性分析,利用广义线性回归评估风险因素。结果与结论:①术前:增加侧方移位风险的变量为粉碎骨块数量,增加短缩移位风险的变量为男性患者,增加Z轴旋转风险的变量为左侧患肢;短缩移位与侧方移位呈显著正相关(r=0.715,P<0.001),短缩移位分别与X轴旋转移位、Y轴旋转移位呈显著正相关(r=0.265,P=0.028;r=0.303,P=0.011),侧方移位与Y轴旋转、Z轴旋转呈显著正相关(r=0.258,P=0.032;r=0.250,P=0.038),X轴旋转与Y轴旋转呈显著正相关(r=0.382,P=0.001),Z轴旋转与Y轴旋转呈显著正相关(r=0.280,P=0.020)。②术后:肩胛骨骨折及粉碎骨块数量为增加术后短缩移位和侧方移位风险的变量:术前X、Y、Z轴的旋转移位分别是增加术后X、Y、Z轴旋转移位的风险变量。术后侧方移位与术后短缩移位呈显著正相关(r=0.584,P=0.000),术后侧方移位也与术后Y轴旋转、Z轴旋转呈显著正相关(r=0.360,P=0.002;r=0.250,P=0.038),术后Y轴旋转与术后Z轴旋转呈出显著正相关(r=0.248,P=0.040)。③结果表明:手术前后锁骨断端的三维移位受多种因素的影响,尤其与粉碎骨块数量、肩胛骨骨折、性别、原始旋转移位等因素关系密切,同时各种移位之间存在复杂的相关性,尤其短缩移位与侧方移位之间的相关性最强。

关键词： 国家发展战略需求   教师   数字素养   信息技术   数字化转型  

摘要： 信息时代,人工智能发展、教育数字化转型、大数据技术应用和国际经验借鉴给教师数字素养培育提供了难得的契机。然而现阶段,教师数字素养培育还面临理念滞后、培育系统不健全、主客观因素制约、保障乏力等困境。文章采用经验总结法等方法提出提升主体意识、构建系统课程体系、优化多元协同培育机制和健全教师数字素养培育的全方位保障体系。

关键词： 甲状腺结节   彩色多普勒超声   超声弹性成像   诊断效能  

摘要： 目的:针对不同检查方式分别应用于甲状腺结节性质(良、恶性)鉴别中的价值及意义进行分析,为临床诊断甲状腺结节性质提供参考依据。方法:回顾性分析河南科技大学第一附属医院2023年1月至2024年1月收治的240例甲状腺结节患者(275个结节)的临床资料,对所有患者均予以彩色多普勒超声、超声弹性成像单独及联合检查,比较彩色多普勒超声特征、超声弹性成像分级对良恶性结节的评估结果、两者单独及联合检查的诊断效能。结果:经金标准检查结果显示:恶性、良性结节分别为55个、220个。相比良性结节的各项超声特征评估结果(病灶形态不规则、回声不均匀等),恶性结节对其的检出率均更高;良性结节、恶性结节弹性成像分级进行比较能够发现,后者IV级、V级占比更高,I-III级占比更低;相比单独彩色多普勒超声、超声弹性成像检查,两者联合诊断的灵敏度更高,差异有统计学意义(P<0.05)。结论:临床上在对甲状腺结节性质(良、恶性)的鉴别中,相比不同检查方式的单独应用,弹性成像与彩超联合应用的诊断优势更佳,效能更高。

关键词： 溶瘤腺病毒   DP7-C/DOTAP阳离子脂质体   卵巢癌  

摘要： 目的利用DP7-C/DOTAP脂质体作为腺病毒运载工具,一方面通过DP7-C/DOTAP脂质体增强溶瘤腺病毒转染CAR受体低表达肿瘤细胞,克服溶瘤腺病毒在转染细胞时受到的CAR限制,提高转染效率;另一方面通过用DP7-C/DOTAP脂质体包裹溶瘤腺病毒,保护溶瘤腺病毒不被中和抗体清除。验证两方面增强溶瘤腺病毒的“溶瘤”作用。方法采用薄膜分散法制备DP7-C修饰的DOTAP脂质体(DP7-C/DOTAP),将腺病毒(Ad)与DP7-C/DOTAP脂质体在体外孵育形成DP7-C/DOTAP/Ad复合物。对DP7-C/DOTAP/Ad复合物的粒径、电位和形态学进行表征。然后在体外检测DP7-C/DOTAP/Ad复合物转染CAR受体低表达肿瘤细胞的效率及抵抗腺病毒中和抗体的功效。最后在小鼠中验证DP7-C/DOTAP脂质体促进溶瘤腺病毒H101的抗肿瘤效果。结果DP7-C/DOTAP脂质体其粒径分布在140~200 nm,电位为48~58 mV,透射电镜结果显示DP7-C/DOTAP/Ad复合物制备成功。与Ad相比,DP7-C/DOTAP/Ad复合物可显著提高低表达CAR受体卵巢癌细胞SKOV3的转染效率,同时DP7-C/DOTAP脂质体可以起到保护腺病毒不被中和抗体识别和清除的作用。在SKOV3卵巢癌皮下移植瘤模型中,单独H101组抑瘤率为23.90%,H101/DP7-C/DOTAP组抑瘤率为54.81%,可更好地抑制肿瘤生长(P<0.05)。结论DP7-C/DOTAP脂质体包裹腺病毒可增强腺病毒的转染效率和杀伤效果。DP7-C/DOTAP脂质体可有效促进腺病毒转染CAR低表达细胞。DP7-C/DOTAP脂质体可以对腺病毒起到良好的保护效果,不被抗腺病毒中和抗体中和。在动物实验中初步证明采用DP7-C/DOTAP脂质体能够增强溶瘤病毒的抗肿瘤效用。

关键词： 地理信息   原则   减量化   增量指标  

摘要： 面对镇、村级规划中出现的土地指标供需关系错配、建设用地选址受土地用途管制影响等问题,本文深入研究基于地理信息的土地供给方式,创新探索用地资源优化配置技术方法,提出利用地理信息技术,基于供需平衡原则、差别化配置原则、协调性等原则,获取建设用地减量化的流量指标、利用弹性空间获取增量指标等方式,保障镇村建设用地供给,推动乡镇工业化和城镇化的快速推进,从土地供给角度为镇、村级规划的土地资源要素合理配置提供支持。

关键词： 防癌饮食   抗氧化剂   膳食纤维   智商税  

摘要： 通过调整饮食就能预防癌症?防癌饮食真的能防癌吗?是智商税吗?防癌饮食是一种通过均衡摄入营养物质来降低癌症风险的饮食习惯,它主要是通过摄入富含抗氧化剂、膳食纤维、维生素和矿物质的食物,降低致癌物暴露、增强机体抗氧化与免疫能力,从而达到降低某些癌症患病风险的目的。防癌饮食并不是智商税,而是基于科学研究提出的健康建议,有助于维持身体健康,减少患癌概率。

关键词： Gradient nano-grained NiTi SMA   Multiscale continuum model   Analytical solution   Martensite transformation   Superelasticity  

摘要： A multiscale nonlocal continuum model is proposed to describe the superelastic deformation of gradient nano-grained NiTi shape memory alloys (SMAs). At the mesoscopic scale, the polycrystalline aggregate is regarded as a composite, i.e., the grain-interior (GI) phase is assumed to be a cuboidal inclusion embedded in a matrix of grain-boundary (GB) phase. An intrinsic energetic length and a gradient energy are introduced into the Helmholtz free energy of the GI phase. The criterion of martensite transformation (MT) is derived based on the principle of virtual power and second law of thermodynamics. The hindering effect of GB on MT in GI phase is addressed. By deriving the analytical solution of the proposed model and introducing a scale transition rule, the overall and local stress-strain responses of the specimen at the macroscopic scale are obtained. The prediction capability of the proposed model is verified by comparing the analytical solution with the experiment. The influences of the distribution form for the grain size (GS) on the superelastic deformation of gradient nano-grained NiTi SMAs are further predicted and discussed. The analytical form and low computational cost of the proposed model make it an appropriate theoretical tool to design the gradient nano-grained SMAs with desired mechanical property.