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排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Patricia A. Miguez Stephen A. Tuin Adam G. Robinson Joyce Belcher Prapaporn Jongwattanapisan Kimberly Perley Vinicius de Paiva Gon«alves Arash Hanifi Nancy Pleshko Elisabeth R. Barton 《International journal of molecular sciences》2021,22(6)
This study evaluated the direct effect of a phytochemical, hesperidin, on pre-osteoblast cell function as well as osteogenesis and collagen matrix quality, as there is little known about hesperidin’s influence in mineralized tissue formation and regeneration. Hesperidin was added to a culture of MC3T3-E1 cells at various concentrations. Cell proliferation, viability, osteogenic gene expression and deposited collagen matrix analyses were performed. Treatment with hesperidin showed significant upregulation of osteogenic markers, particularly with lower doses. Mature and compact collagen fibrils in hesperidin-treated cultures were observed by picrosirius red staining (PSR), although a thinner matrix layer was present for the higher dose of hesperidin compared to osteogenic media alone. Fourier-transform infrared spectroscopy indicated a better mineral-to-matrix ratio and matrix distribution in cultures exposed to hesperidin and confirmed less collagen deposited with the 100-µM dose of hesperidin. In vivo, hesperidin combined with a suboptimal dose of bone morphogenetic protein 2 (BMP2) (dose unable to promote healing of a rat mandible critical-sized bone defect) in a collagenous scaffold promoted a well-controlled (not ectopic) pattern of bone formation as compared to a large dose of BMP2 (previously defined as optimal in healing the critical-sized defect, although of ectopic nature). PSR staining of newly formed bone demonstrated that hesperidin can promote maturation of bone organic matrix. Our findings show, for the first time, that hesperidin has a modulatory role in mineralized tissue formation via not only osteoblast cell differentiation but also matrix organization and matrix-to-mineral ratio and could be a potential adjunct in regenerative bone therapies. 相似文献
2.
This paper focuses on the configuration design of flexure hinges with a prescribed compliance matrix and preset rotational center position. A new method for the topology optimization of flexure hinges is proposed based on the adaptive spring model and stress constraint. The hinge optimization model is formulated by maximizing the bending displacement with a spring while optimizing the compliance matrix to a prescribed value. To avoid numerical instability, an artificial spring is used as an auxiliary calculation, and a new strategy is developed for adaptively adjusting the spring stiffness according to the prescribed compliance matrix. The maximum stress of flexure hinge is limited by using a normalized P-norm of the effective von Mises stress, and a position constraint of rotational center is proposed to predetermine the position of the rotational center. In addition, to reduce the error of the stress measurement, a simple but effective filtering method is presented to obtain a complete black-and-white design. Numerical examples are used to verify the proposed method. Topology results show that the obtained flexure hinges have the prescribed compliance matrix and preset rotational center position while also meeting the stress requirements. 相似文献
3.
Matrix Manipulation of Directly-Synthesized PbS Quantum Dot Inks Enabled by Coordination Engineering
Fei Li Yang Liu Guozheng Shi Wei Chen Renjun Guo Dong Liu Yaohong Zhang Yongjie Wang Xing Meng Xuliang Zhang You Lv Wei Deng Qing Zhang Yao Shi Yifan Chen Kai Wang Qing Shen Zeke Liu Peter Müller-Buschbaum Wanli Ma 《Advanced functional materials》2021,31(45):2104457
The direct-synthesis of conductive PbS quantum dot (QD) ink is facile, scalable, and low-cost, boosting the future commercialization of optoelectronics based on colloidal QDs. However, manipulating the QD matrix structures still is a challenge, which limits the corresponding QD solar cell performance. Here, for the first time a coordination-engineering strategy to finely adjust the matrix thickness around the QDs is presented, in which halogen salts are introduced into the reaction to convert the excessive insulating lead iodide into soluble iodoplumbate species. As a result, the obtained QD film exhibits shrunk insulating shells, leading to higher charge carrier transport and superior surface passivation compared to the control devices. A significantly improved power-conversion efficiency from 10.52% to 12.12% can be achieved after the matrix engineering. Therefore, the work shows high significance in promoting the practical application of directly synthesized PbS QD inks in large-area low-cost optoelectronic devices. 相似文献
4.
Andrea Angius Antonio Mario Scanu Caterina Arru Maria Rosaria Muroni Vincenzo Rallo Giulia Deiana Maria Chiara Ninniri Ciriaco Carru Alberto Porcu Giovanna Pira Paolo Uva Paolo Cossu-Rocca Maria Rosaria De Miglio 《International journal of molecular sciences》2021,22(4)
Colorectal cancer (CRC) is a leading cause of cancer death worldwide, and about 20% is metastatic at diagnosis and untreatable. Increasing evidence suggests that the heterogeneous nature of CRC is related to colorectal cancer stem cells (CCSCs), a small cells population with stemness behaviors and responsible for tumor progression, recurrence, and therapy resistance. Growing knowledge of stem cells (SCs) biology has rapidly improved uncovering the molecular mechanisms and possible crosstalk/feedback loops between signaling pathways that directly influence intestinal homeostasis and tumorigenesis. The generation of CCSCs is probably connected to genetic changes in members of signaling pathways, which control self-renewal and pluripotency in SCs and then establish function and phenotype of CCSCs. Particularly, various deregulated CCSC-related miRNAs have been reported to modulate stemness features, controlling CCSCs functions such as regulation of cell cycle genes expression, epithelial-mesenchymal transition, metastasization, and drug-resistance mechanisms. Primarily, CCSC-related miRNAs work by regulating mainly signal pathways known to be involved in CCSCs biology. This review intends to summarize the epigenetic findings linked to miRNAome in the maintenance and regulation of CCSCs, including their relationships with different signaling pathways, which should help to identify specific diagnostic, prognostic, and predictive biomarkers for CRC, but also develop innovative CCSCs-targeted therapies. 相似文献
5.
To advance organ-on-a-chip development and other areas befitting from physiologically-relevant biomembranes,a microfluidic platform is presented for synthesis of biomembranes during gelation and investigation into their role as extracellular matrix supports.In this work,high-throughput studies of collagen,chitosan,and collagen-chitosan hybrid biomembranes were carried out to characterize and compare key properties as a function of the applied hydrodynamic conditions during gelation.Specifically,depending on the biopolymer material used,varying flow conditions during biomembrane gelation caused width,uniformity,and swelling ratio to be differently affected and controllable.Finally,cell viability studies of seeded fibroblasts were conducted,thus showing the potential for biological applications. 相似文献
6.
研究了遭受网络攻击的双层结构多智能体系统的一致性问题。针对包含领导层和跟随者层的双层网络结构的多智能体系统,考虑了如下情况:领导层相邻智能体之间为友好合作关系,跟随者层相邻智能体之间既包含友好合作也包含对抗竞争关系,同时领导层与跟随者层中部分对应智能体之间存在牵制关系。分析了受网络攻击的领导层多智能体系统、跟随者层多智能体系统和双层网络结构多智能体系统的节点之间的一致性关系。基于线性矩阵不等式(LMI)、李雅普诺夫稳定性理论和图论等相关知识给出了领导层多智能体系统节点间实现一致,跟随者层多智能体系统节点间实现二分一致,以及双层结构的多智能体系统之间实现点对点二分一致的充分性判据。最后,给出了具体的数值仿真例子,实现了遭受网络攻击的双层结构多智能体系统的一致性,验证了所给出的判据的有效性。 相似文献
7.
将小波变换多尺度理论用于分析确定共生矩阵最佳步长参数值,利用小波变换对原始图像进行分解,根据具体纹理图像,选择合适小波子图像(近似图像或其细节子图像)进行纹理分析,通过计算分解图像的纹理特征参数(对比度)确定最佳步长参数。当步长参数为最优值时,计算所得纹理特征参数值将处于周期极值位置,其利于纹理分析。相对于原始图像,分解图像数据量小,在寻优共生矩阵最佳步长参数时,计算复杂度及时间消耗都有所降低。实验验证,基于小波分解图像所得最佳步长参数值是精确的。 相似文献
8.
软件缺陷预测是软件工程中的一个研究热点问题,通常软件缺陷预测的研究工作主要关注于软件模块是否存在缺陷和软件模块存在缺陷的数量。目前软件缺陷数量研究主要集中在基于缺陷数的软件模块排序。为提高软件模块排序的准确度,提出一种回环软件缺陷数量预测模型。此模型主要包括回环特征选择和缺陷预测两部分。在回环特征选择部分,将改进的密度峰值聚类算法和包裹式特征选择方法相结合,以回环的方式动态的选出最优特征,并训练学习器;陷预测部分采用反距离加权集成的方式得到预测结果。实验结果表明,此模型相比于LRCR、GRCR、LR、MLP、GP、NBR、ZIP分别提升了10.36%、28.74%、13.51%、36.61%、25.30%、60.14%、54.72%,有助于提高软件缺陷预测准确性。 相似文献
9.
针对目前在变电站中应用广泛的巡检机器人,探讨了其巡检路径的问题,依据离散数学理论中的哈密顿回路方法和路径的常规规划算法,研究了一种变电站的巡检路径为矩形分布时的机器人巡检路径问题。针对不同巡检方式,分别提出:全局巡检方式,采用新提出的哈密顿算法,当巡视起点被设定后,其他被巡视的任何点均可被归类,从而找出其巡检路径的哈密顿回路;重点设备巡检方式,采用Dijkstra算法和遗传算法相结合的方法;固定点巡检方式,采用Dijkstra算法。其中,三种巡检方式分别针对电量充足、低电量返回及充电完毕继续巡视等方面给出仿真结果,并将其在某变电站进行了试用。研究结果表明,三种巡检方式下的算法均有效可行,新提出的哈密顿回路算法巡视的路径比常规方法相对要短,算法的运算速度相对更快。 相似文献
10.
Carla Marina Santos Feldhaus Roseli Künzel Máximo Siu Li Ana Paula de Azevedo Marques 《Journal of the American Ceramic Society》2021,104(10):5192-5204
The compounds based on calcium molybdate (CaMoO4) are the subject of extensive research due to their excellent optical properties and a broad range of potential technological applications. In this work, we report a systematic study of CaMoO4:Tm3+ phosphors synthesized by coprecipitation and processed in a microwave-hydrothermal system at low temperature (100°C) and stirring. The effect of the Tm3+ doping content (0%–12%) is studied in full detail to understand their role in the CaMoO4:Tm3+ morphological, structural, and luminescent properties. The X-ray diffraction, Raman, and Fourier Transform Infrared spectroscopic techniques revealed that all the prepared powders have a tetragonal crystal structure with a distinct density of cation vacancies and structural disorders. The band gap remains almost constant for doping levels lower than 8%, but it narrows strongly for powders doped with 12% Tm3+ ions. The designed phosphors have shown two emission bands in which intensity depends on the Tm3+ ions doping level. For doping levels lower than 2%, the photoluminescence profile displays a broad emission band peaking at 543 nm (green). For concentrations higher than 4%, the band centered at 543 nm decreases in intensity and the near-infrared emission band at around 800 nm, assigned to 3F3, 3H4 → 3H6 transitions from Tm3+ ion, become more intense. The outcomes of this work reveal that appropriated Tm3+ ions doping levels can be applied to suppress the PL emission in the visible range and improve that in the near-infrared region in CaMoO4-based materials. 相似文献