长江经济带城市生态效率演变及驱动因素分析

城市生态文明建设依托于生态效率的改善，基于2005—2016年长江经济带107座城市面板数据，采用超效率SBM（slacks-based measure)模型测算生态效率，并结合探索性空间分析与空间马尔科夫链等探讨生态效率时空演化格局的内在规律， 实证分析生态效率驱动因素的影响效果。研究表明：2005—2016年经济带生态效率总体呈平稳态势，上、中、下游呈现“阶梯型”分布，下游依次优于中游和上游地区，部分地区生态效率呈“两级型”分化趋势；城市间生态效率发展存在空间联动效应，与生态效率高的城市为邻，其正向溢出作用促进城市状态向高水平跃迁，而与生态效率低的城市为邻，其负向作用拉动城市状态向低水平发展；人口规模与产业升级对经济带不同流域具有异质性作用，其提升下游生态效率而抑制中游和上游生态效率，产业升级与生态效率存在“U”型关联，意味着产业升级在短期内并不能使生态效率状态改善，而经济发展有利于促进生态效率向高水平状态演变。     

Drag Power Loss Investigation in Cylindrical Roller Bearings Using CFD Approach

In high-speed rolling element bearings, the drag forces can be prominent and it is demonstrated in this investigation that the classical models may not be appropriate for correctly estimating this power loss contribution. A modification of the models is thus proposed, including the usual drag forces formulation relying upon the drag coefficient to be evaluated from a numerical computational fluid dynamics (CFD) approach. A three-dimensional approach that considers both the rings and the cylinder ends seems the only adequate approach to be used because a two-dimensional approach predicts a drag coefficient value that is too low. When using the former computed drag coefficient for the evaluation of the total power losses, high values of oil volume fraction must be employed to recover the measured power losses.     

Mechanosensation and Mechanotransduction by Lymphatic Endothelial Cells Act as Important Regulators of Lymphatic Development and Function

Our understanding of the function and development of the lymphatic system is expanding rapidly due to the identification of specific molecular markers and the availability of novel genetic approaches. In connection, it has been demonstrated that mechanical forces contribute to the endothelial cell fate commitment and play a critical role in influencing lymphatic endothelial cell shape and alignment by promoting sprouting, development, maturation of the lymphatic network, and coordinating lymphatic valve morphogenesis and the stabilization of lymphatic valves. However, the mechanosignaling and mechanotransduction pathways involved in these processes are poorly understood. Here, we provide an overview of the impact of mechanical forces on lymphatics and summarize the current understanding of the molecular mechanisms involved in the mechanosensation and mechanotransduction by lymphatic endothelial cells. We also discuss how these mechanosensitive pathways affect endothelial cell fate and regulate lymphatic development and function. A better understanding of these mechanisms may provide a deeper insight into the pathophysiology of various diseases associated with impaired lymphatic function, such as lymphedema and may eventually lead to the discovery of novel therapeutic targets for these conditions.     

Topography‐Induced Cell Self‐Organization from Simple to Complex Aggregates

Self‐organization is a fundamental and indispensable process in a living system. To understand cell behavior in vivo such as tumorigenesis, 3D cellular aggregates, instead of 2D cellular sheets, have been employed as a vivid in vitro model for self‐organization. However, most focus on the macroscale wetting and fusion of cellular aggregates. In this study, it is reported that self‐organization of cells from simple to complex aggregates can be induced by multiscale topography through confined templates at the macroscale and cell interactions at the nanoscale. On the one hand, macroscale templates are beneficial for the organization of individual cells into simple and complex cellular aggregates with various shapes. On the other hand, the realization of these macro‐organizations also depends on cell interactions at the nanoscale, as demonstrated by the intimate contact between nanoscale pseudopodia stretched by adjacent frontier cells, much like holding hands and by the variation in the intermolecular interactions based on E‐cadherin. Therefore, these findings may be very meaningful for clarifying the organizational mechanism of tumor development, tissue engineering and regenerative medicine.     

高温处理对牛肉蛋白质化学作用力及肌原纤维蛋白结构的影响

以牛背最长肌为研究对象,对其进行高温处理(110、115、121℃分别加热3、6、9、12、15 min),通过分析蛋白质化学键、傅里叶变换红外光谱、紫外光谱、内源荧光光谱以及蛋白质片段大小等结构信息变化,探讨高温处理对牛肉蛋白质化学作用力及肌原纤维蛋白结构的影响。结果表明,随着处理温度的升高和加热时间的延长,牛肉蛋白中离子键和氢键含量显著下降(P0.05),疏水相互作用和二硫键含量显著升高(P0.05)。肌原纤维蛋白二级结构发生重排,N—H和C—N伸缩振动以及N—H弯曲振动较为明显。高温处理促使芳香族氨基酸残基暴露于分子表面,并改变了肌原纤维蛋白质疏水区域的局部结构和蛋白质的三级结构。此外,在高温处理下肌原纤维蛋白发生了明显的降解聚集,并形成了大量小分子质量的蛋白片段。可见,高温处理能够显著改变牛肉蛋白质的化学作用力及肌原纤维蛋白的结构,本研究为高温处理下牛肉蛋白质变化机制的研究提供参考。     

基于作用力探究凝胶因子与油凝胶之间的构效关系研究进展

近10年来,随着消费者对膳食中减少饱和脂肪酸和消除反式脂肪酸需求的提高以及相关部门要求取缔反式脂肪酸规定的制定,利用凝胶因子结构化植物油形成油凝胶的研究日益增多。诸多研究表明,植物油性质和凝胶因子种类对油凝胶理化性质有显著影响。本文概述了植物油对油凝胶的影响,从诱导形成油凝胶的3个主要作用力:范德华力、氢键、π-π堆积的角度综述了凝胶因子与油凝胶之间的构效关系,为选择与合成一系列高效、价廉的食品级凝胶因子提供思路。     

Self-assembly of nanoparticle-rich interphases in fiber reinforced polymeric composites using migrating agents

Thermoplastic additives, known as migrating agents, can be added to nanoparticle loaded thermosetting resins to form self-assembled nanoparticle structures. Most notably, in fiber reinforced thermosetting composites, self-assembled nanoparticle rich fiber-matrix interphases can be formed. While the self-assembly mechanism remains unclear, depletion interaction correctly describes the types of self-assembled structures formed. Formulations containing modest concentrations of migrating agent form self-assembled fiber-matrix interphases without causing aggregation in the bulk. Slight overdoses of migrating agent can lead to the formation of nanoparticle aggregates in the bulk phase, which can ultimately reduce the mechanical properties of the composite. Even larger overdoses of migrating agent cause the formation of large and open nanoparticle aggregates, indicative of rapid aggregation. Depletion theory predicts that larger molecular weight migrating agents should induce greater attractive forces, thus reducing the concentrations required to form these self-assembled structures. In this study, the migrating agent molecular weight dependence on the self-assembly and aggregation phenomenon are investigated. As predicted by depletion theory, larger molecular weights led to the formation of self-assembled interphases and aggregates at lower concentrations.     

On the equilibrium of funicular polyhedral frames and convex polyhedral force diagrams

This paper presents a three-dimensional extension of graphic statics using polyhedral form and force diagrams for the design of compression-only and tension-only spatial structures with externally applied loads. It explains the concept of 3D structural reciprocity based on Rankine’s original proposition for the equilibrium of spatial frames. It provides a definition for polyhedral reciprocal form and force diagrams that allows including external forces and discusses their geometrical and topological characteristics. This paper furthermore provides a geometrical procedure for constructing a pair of reciprocal polyhedral diagrams from a given polyhedron representing either the form or force diagram of a structural system. Using this method, this paper furthermore suggests a design strategy for finding complex funicular spatial forms in pure compression (or tension), based on the construction of force diagrams through the aggregation of convex polyhedral cells. Finally, it discusses the effect of changes in the geometry of the force diagram on the geometry of the form diagram and the distribution of forces in it.     

Structural properties of nanocomposites based on resole-type phenol-formaldehyde oligomers and detonation nanodiamonds

Using the methods of infrared spectroscopy (IRS) and X-ray photoelectron spectroscopy (XPS), it was shown that short-term high-energy machining of detonation nanodiamonds (DND) leads to structural changes in the crystal structure and functional composition of the surface layer on particles. The possibility of spontaneous formation for stable colloidal systems with a narrow size distribution of mechanically activated DND in phenol-formaldehyde oligomers (PFO) was established. By molecular spectroscopy it was revealed that π → π* interactions of the aromatic rings of PFO are caused by orientational phenomena as a result of hydrogen bonds between an activated DND surface and functional groups of PFO. The effect of DND concentration on the curing reaction parameters ofpsgr the phenol-formaldehyde oligomer was determined by differential scanning calorimetry (DSC). The concentration effect of mechanically activated nanodiamonds on the physical and mechanical characteristics of a composite material based on phenol-formaldehyde binder and polyamide paper (Nomex) was studied. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48582.