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Understanding the guest‐induced dynamic deformation process of covalent organic frameworks (COFs) is vitally important to further increase their stimulus‐response performances. Here we report on the dark‐field microscopic (DFM) imaging approach to in situ monitor the guest‐induced deformation evolution of individual COF‐300 crystals in real time. We observe not only transient and nonequilibrium intermediate deformation states but also local surface curvature‐driven diverse adsorption behaviours of single COF‐300 particles for dichloromethane (DCM), undergoing one, two, and multiple expansion‐contraction deformations as well as contraction‐to‐expansion transition. The surface curvature‐dominated deformations are ascribed to the significant differences in the adsorption capacity for DCM at the curved tip and flat side regions, in which DCM can be adsorbed preferentially by curved tip regions of COF‐300. [ABSTRACT FROM AUTHOR]

Natural gas hydrate nucleation is a complex physical and chemical process that is not well understood presently. In this article, an improved thermodynamic model is proposed to analyze the effects of surface curvature and wettability on methane hydrate nucleation for the first time. The results indicate that methane hydrate nucleation is more difficult on hydrophilic curvature surfaces under the same conditions, with a larger critical nucleation radius and required energy barrier than on hydrophobic surfaces. Furthermore, a convex surface is more favorable for forming methane hydrate under the same conditions than a concave surface. The model's results are critical in elucidating the microscopic mechanism of methane hydrate nucleation and providing a theoretical foundation for developing technologies for strengthening and inhibiting hydrate formation. [ABSTRACT FROM AUTHOR]

The structure of a protein plays a pivotal role in determining its function. Often, the protein surface's shape and curvature dictate its nature of interaction with other proteins and biomolecules. However, marked by corrugations and roughness, a protein's surface representation poses significant challenges for its curvature‐based characterization. In the present study, we employ unsupervised machine learning to segment the protein surface into patches. To measure the surface curvature of a patch, we present an algebraic sphere fitting method that is fast, accurate, and robust. Moreover, we use local curvatures to show the existence of "shape complementarity" in protein–protein, antigen–antibody, and protein‐ligand interfaces. We believe that the current approach could help understand the relationship between protein structure and its biological function and can be used to find binding partners of a given protein. [ABSTRACT FROM AUTHOR]

Recent evidence shows that the curvature of porous scaffold plays a significant role in guiding tissue regeneration. However, the underlying mechanism remains controversial to date. In this study, we developed an in silico model to simulate the effect of surface curvature on the osteoconduction of scaffold implants, which comprises the primary aspects of bone regeneration. Selective laser melting was used to manufacture a titanium scaffold with channels representative of different strut curvatures for in vivo assessment. The titanium scaffold was implanted in the femur condyles of rabbits to validate the mathematical model. Simulation results suggest that the curvature affected the distribution of growth factors and subsequently induced the migration of osteoblast lineage cells and bone deposition to the locations with higher curvature. The predictions of the mathematical model are in good agreement with the in vivo assessment results, in which newly formed bone first appeared adjacent to the vertices of the major axes in elliptical channels. The mechanism of curvature‐guided osteoconduction may provide a guide for the design optimization of scaffold implants to achieve enhanced bone ingrowth. [ABSTRACT FROM AUTHOR]

Thermal protection effect of reactive fire protection systems on small‐scale steel components with curved surfaces Intumescent fire protection coatings, also referred to as reactive fire protection systems, are often used to protect steel components from heating up too quickly in the event of a fire. The products are particularly suitable due to profile‐following application as well as the comparatively low coating thickness. If exposed to fire, the intumescent coating foams up and forms a thermal protective layer around the steel profile. This slows down the heating of the steel and delays the temperature‐related loss of strength, which improves the fire resistance of the steel component. From fire tests it is known that the performance of intumescent coatings on steel profiles with a curved surface is usually worse than on comparable components with a flat surface. The following article presents the theoretical background as well as the results from fire tests on small‐scale specimens to show the influence of surface curvature on the thermal protective effect of intumescent fire protection coatings. The systematic investigations show that with increasing surface curvature, the performance of the intumescent coating tends to decrease. When assessing the thermal protective effect of an intumescent coating, the surface curvature of a steel component should be considered. Focusing solely on the profile factor of a steel profile is generally not sufficient. The research forms the basis for the development of screening tests to assess the suitability of intumescent coatings for curved surfaces, enabling a pre‐selection of products for this application. [ABSTRACT FROM AUTHOR]

Biological tissues comprise complex structural environments known to influence cell behavior via multiple interdependent sensing and transduction mechanisms. Yet, and despite the predominantly nonplanar geometry of these environments, the impact of tissue-size (milliscale) curvature on cell behavior is largely overlooked or underestimated. This study explores how concave, hemicylinder-shaped surfaces 3-50 mm in diameter affect the migration, proliferation, orientation, and differentiation of C2C12 myoblasts. Notably, these milliscale cues significantly affect cell responses compared with planar substrates, with myoblasts grown on surfaces 7.5-15 mm in diameter showing prevalent migration and alignment parallel to the curvature axis. Moreover, surfaces within this curvature range promote myoblast differentiation and the formation of denser, more compact tissues comprising highly oriented multinucleated myotubes. Based on the similarity of effects, it is further proposed that myoblast susceptibility to substrate curvature depends on mechanotransduction signaling. This model thus supports the notion that cellular responses to substrate curvature and compliance share the same molecular pathways and that control of cell behavior can be achieved via modulation of either individual parameter or in combination. This correlation is relevant for elucidating how muscle tissue forms and heals, as well as for designing better biomaterials and more appropriate cell-surface interfaces. [ABSTRACT FROM AUTHOR]

Important three-dimensional spatial features such as depth and surface concavity can be difficult to convey clearly in the context of two-dimensional images. In the area of macromolecular visualization, the computer graphics technique of ray-tracing can be helpful, but further techniques for emphasizing surface concavity can give clearer perceptions of depth. The notion of diffusion accessibility is well-suited for emphasizing such features of macromolecular surfaces, but a method for calculating diffusion accessibility has not been made widely available. Here we make available a web-based platform that performs the necessary calculation by solving the Laplace equation for steady state diffusion, and produces scripts for visualization that emphasize surface depth by coloring according to diffusion accessibility. The URL is . [ABSTRACT FROM AUTHOR]

One fundamental objective in geomorphometry is to extract signatures of geomorphologic processes on different spatial scales from digital terrain models (DTMs) and to describe the complexity of landforms as the synthesis of those individual imprints. We present an approach for characterizing land surfaces on multiple, spatially varying local scales. We approximate terrain surfaces locally to calculate surface derivatives at different window sizes. Local scale behaviour diagrams are used to define dominant scale ranges and multiple curvatures for each surface point. Multi-scale landform analysis leads to improved models of surface derivatives and new landform classifications, applicable in geomorphology, soil science and hydrology. [ABSTRACT FROM AUTHOR]