The precise synthesis of polypeptides with varying chain topologies has attracted significant interest due to their diverse functional applications. However, conventional polymerization of environment-susceptible N-carboxylic anhydride (NCA) monomers using primary amine initiators suffers from inevitable side reactions, greatly compromising chain-end fidelity and thus disabling the access to polypeptides with high-order architectures. Herein, we develop a general and robust strategy based on normal amine mechanism (NAM) for the synthesis of various topological polypeptides via the polymerization of moisture-insensitive and air-tolerant N-phenoxycarbonyl-functionalized amino acid (NPCA) precursors using primary amine hydrochloride as initiators. This strategy enables the synthesis of block, star, star-block, brush-type, and multiblock (co)polypeptides with desired sequences, predictable molecular weights, low polydispersity, and high-fidelity chain ends even under open-air conditions. Remarkably, the robustness of this approach has been exemplified by the precise synthesis of well-defined photoresponsive decablock copolypeptides, exhibiting a spontaneous morphological evolution from polymersomes to lamellae nanostructures upon light irradiation. This work provides a general and reliable tool for the synthesis of polypeptides with varying topologies, shedding light on the development of synthetic polypeptide-based materials.
Low-cycle reciprocating loading tests were carried out on a steel frame with prefabricated beam-only connected steel plate shear wall (specimen A) and a steel frame with welded beam-only connected steel plate shear wall (specimen B). The seismic performance of the two different types of steel frame-steel plate shear wall specimens was studied and the failure modes, hysteresis curve, skeleton curve, and seismic performance index, etc of two groups of specimens were obtained, together with the studies of failure characteristics, ductility, energy dissipation, and stiffness degradation of the two specimens. The results showed that the assembled steel frame-steel plate shear wall with connection joints of steel shear wall with discontinuous cover plate connected on both sides (DCPC) have good seismic performance. On the basis of no loss of seismic performance, DCPC joints can provide better energy dissipation capacity than traditional welded steel plate shear wall structures and ensure the good postearthquake repair function.
As for the lack of the constraint on operations in traditional real-time collaborative environment, the paper introduces to adopt right allocation technique to support the document management of the shared document of different work groups. The paper gives formal definition of the Tree Document Model supporting role management, describes the configuration process of the roles, defines the formats of the right operations, proposes conflict detection and resolution strategies for Apply/Apply, Apply/Delete and Apply/Update conflicts. Besides, the paper improves the address space transformation strategy to guarantee the correct execution of the right operations in the distributed sites. Efficiency analysis of the improved algorithm is given and the application of this strategy in the Co-AutoCAD system proves the validity of the whole strategy.
Abstract. Real-time collaborative graphic editors allow a group of users to view and edit the same graphic document at the same time from geographically dispersed sites connected by communication networks. Bitmap-based graphic editing systems are special collaborative editing systems, and Undo/Redo operations are intricate problems in this field. Existing solutions add extra space, thus showing low efficiency of the algorithms. In this paper, based on Multiversion strategy, we propose a new solution to solve the Undo/Redo consistency problem, and consider three possible cases: all-causal, all-independent and causal-independent-mixed operations. In addition, compared with previous collaborative algorithms, the algorithm proposed in this paper supports selective Undo, without requiring additional space and the implementation of Undo/Redo is more flexible.
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