Structural and functional basis of bacteriophage K64-ORF41 depolymerase for capsular polysaccharide degradation of Klebsiella pneumoniae K64.

Capsule polysaccharide is an important virulence factor of Klebsiella pneumoniae (K. pneumoniae), which protects bacteria against the host immune response. A promising therapeutic approach is using phage-derived depolymerases to degrade the capsular polysaccharide and expose and sensitize the bacteria to the host immune system. Here we determined the cryo-electron microscopy (cryo-EM) structures of a bacteriophage tail-spike protein against K. pneumoniae K64, ORF41 (K64-ORF41) and ORF41 in EDTA condition (K64-ORF41EDTA), at 2.37 Å and 2.50 Å resolution, respectively, for the first time. K64-ORF41 exists as a trimer and each protomer contains a ß-helix domain including a right-handed parallel ß-sheet helix fold capped at both ends, an insertion domain, and one ß-sheet jellyroll domain. Moreover, our structural comparison with other depolymerases of K. pneumoniae suggests that the catalytic residues (Tyr528, His574 and Arg628) are highly conserved although the substrate of capsule polysaccharide is variable. Besides that, we figured out the important residues involved in the substrate binding pocket including Arg405, Tyr526, Trp550 and Phe669. This study establishes the structural and functional basis for the promising phage-derived broad-spectrum activity depolymerase therapeutics and effective CPS-degrading agents for the treatment of carbapenem-resistant K. pneumoniae K64 infections.

The Analysis of the Innovation Consciousness of College Student Entrepreneurs Under the Teaching Concept of Chinese Excellent Traditional Culture.

The purpose of this study was to analyze the current situation of the entrepreneurial consciousness of college student entrepreneurs and to explore the role of innovative and entrepreneurial talents in social and economic development. Based on the teaching concept of Chinese excellent traditional culture, first, the relevant theories of innovation and entrepreneurship, as well as the characteristics of entrepreneurial talents in colleges and entrepreneurs, are analyzed and elaborated; moreover, the definition of college student entrepreneur is explained; then, from the perspective of entrepreneurial teaching management, entrepreneurial education, and place support, the questionnaire method is selected to show the understanding of the entrepreneurship of college students; finally, based on the Cobb-Douglas function, the model before and after the introduction of innovative and entrepreneurial talents is tested and analyzed. Investigation and analysis suggest that most college students have entrepreneurial intention, and 61.5% of them choose to start their own business after having working experience; the relative freedom of time and space is the main factor to attract college students to start their own businesses, accounting for 42.3%; 69.3% of college students think that capital is a restricting factor for entrepreneurship, while 76.2% think that lack of experience is a major restricting factor for entrepreneurship; college students have a certain demand for entrepreneurship training and guidance from the school, especially in the setting of entrepreneurship incubation park and resource pool; the characteristics of entrepreneurship, professional skills, and interpersonal resources are more crucial for college students; most college students have a positive cognition of the excellent traditional Chinese teaching concepts; the analysis based on the Cobb-Douglas function reveals that the introduction of innovative and entrepreneurial talents can promote economic development. This exploration has a positive effect on the cultivation of awareness of college students of entrepreneurship and innovation, as well as the relationship discussion between the introduction of innovative and entrepreneurial talents and social economy.

Intelligent Shape-Morphing Micromachines.

Intelligent machines are capable of switching shape configurations to adapt to changes in dynamic environments and thus have offered the potentials in many applications such as precision medicine, lab on a chip, and bioengineering. Even though the developments of smart materials and advanced micro/nanomanufacturing are flouring, how to achieve intelligent shape-morphing machines at micro/nanoscales is still significantly challenging due to the lack of design methods and strategies especially for small-scale shape transformations. This review is aimed at summarizing the principles and methods for the construction of intelligent shape-morphing micromachines by introducing the dimensions, modes, realization methods, and applications of shape-morphing micromachines. Meanwhile, this review highlights the advantages and challenges in shape transformations by comparing micromachines with the macroscale counterparts and presents the future outlines for the next generation of intelligent shape-morphing micromachines.

Magnetic cilia carpets with programmable metachronal waves.

Metachronal waves commonly exist in natural cilia carpets. These emergent phenomena, which originate from phase differences between neighbouring self-beating cilia, are essential for biological transport processes including locomotion, liquid pumping, feeding, and cell delivery. However, studies of such complex active systems are limited, particularly from the experimental side. Here we report magnetically actuated, soft, artificial cilia carpets. By stretching and folding onto curved templates, programmable magnetization patterns can be encoded into artificial cilia carpets, which exhibit metachronal waves in dynamic magnetic fields. We have tested both the transport capabilities in a fluid environment and the locomotion capabilities on a solid surface. This robotic system provides a highly customizable experimental platform that not only assists in understanding fundamental rules of natural cilia carpets, but also paves a path to cilia-inspired soft robots for future biomedical applications.

Superrepellency of underwater hierarchical structures on Salvinia leaf.

Biomimetic superhydrophobic surfaces display many excellent underwater functionalities, which attribute to the slippery air mattress trapped in the structures on the surface. However, the air mattress is easy to collapse due to various disturbances, leading to the fully wetted Wenzel state, while the water filling the microstructures is difficult to be repelled to completely recover the air mattress even on superhydrophobic surfaces like lotus leaves. Beyond superhydrophobicity, here we find that the floating fern, Salvinia molesta, has the superrepellent capability to efficiently replace the water in the microstructures with air and robustly recover the continuous air mattress. The hierarchical structures on the leaf surface are demonstrated to be crucial to the recovery. The interconnected wedge-shaped grooves between epidermal cells are key to the spontaneous spreading of air over the entire leaf governed by a gas wicking effect to form a thin air film, which provides a base for the later growth of the air mattress in thickness synchronously along the hairy structures. Inspired by nature, biomimetic artificial Salvinia surfaces are fabricated using 3D printing technology, which successfully achieves a complete recovery of a continuous air mattress to exactly imitate the superrepellent capability of Salvinia leaves. This finding will benefit the design principles of water-repellent materials and expand their underwater applications, especially in extreme environments.

Publisher Correction: Nanomagnetic encoding of shape-morphing micromachines.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Nanomagnetic encoding of shape-morphing micromachines.

Shape-morphing systems, which can perform complex tasks through morphological transformations, are of great interest for future applications in minimally invasive medicine1,2, soft robotics3-6, active metamaterials7 and smart surfaces8. With current fabrication methods, shape-morphing configurations have been embedded into structural design by, for example, spatial distribution of heterogeneous materials9-14, which cannot be altered once fabricated. The systems are therefore restricted to a single type of transformation that is predetermined by their geometry. Here we develop a strategy to encode multiple shape-morphing instructions into a micromachine by programming the magnetic configurations of arrays of single-domain nanomagnets on connected panels. This programming is achieved by applying a specific sequence of magnetic fields to nanomagnets with suitably tailored switching fields, and results in specific shape transformations of the customized micromachines under an applied magnetic field. Using this concept, we have built an assembly of modular units that can be programmed to morph into letters of the alphabet, and we have constructed a microscale 'bird' capable of complex behaviours, including 'flapping', 'hovering', 'turning' and 'side-slipping'. This establishes a route for the creation of future intelligent microsystems that are reconfigurable and reprogrammable in situ, and that can therefore adapt to complex situations.

Matryoshka-Inspired Micro-Origami Capsules to Enhance Loading, Encapsulation, and Transport of Drugs.

Stimuli-responsive hydrogels are promising candidates for use in the targeted delivery of drugs using microrobotics. These devices enable the delivery and sustained release of quantities of drugs several times greater than their dry weight and are responsive to external stimuli. However, existing systems have two major drawbacks: (1) severe drug leakage before reaching the targeted areas within the body and (2) impeded locomotion through liquids due to the inherent hydrophilicity of hydrogels. This article outlines an approach to the assembly of hydrogel-based microcapsules in which one device is assembled within another to prevent drug leakage during transport. Inspired by the famous Russian stacking dolls (Matryoshka), the proposed scheme not only improves drug-loading efficiency but also facilitates the movement of hydrogel-based microcapsules driven by an external magnetic field. At room temperature, drug leakage from the hydrogel matrix is 90%. However, at body temperature the device folds up and assembles to encapsulate the drug, thereby reducing leakage to a mere 6%. The Matryoshka-inspired micro-origami capsule (MIMC) can disassemble autonomously when it arrives at a targeted site, where the temperature is slightly above body temperature. Up to 30% of the encapsulated drug was shown to diffuse from the hydrogel matrix within 1 h when it unfolds and disassembles. The MIMC is also shown to enhance the movement of magnetically driven microcapsules while navigating through media with a low Reynolds number. The translational velocity of the proposed MIMC (four hydrogel-based microcapsules) driven by magnetic gradients is more than three times greater than that of a conventional (single) hydrogel-based microcapsule.

Analysis of topological relationships and network properties in the interactions of human beings.

In the animal world, various kinds of collective motions have been found and proven to be efficient ways of carrying out some activities such as searching for food and avoiding predators. Many scholars research the interactions of collective behaviors of human beings according to the rules of collective behaviors of animals. Based on the Lennard-Jones potential function and a self-organization process, our paper proposes a topological communication model to simulate the collective behaviors of human beings. In the results of simulations, we find various types of collective behavior and fission behavior and discover the threshold for the emergence of collective behavior, which is the range five to seven for the number of topology K. According to the analysis of network properties of the model, the in-degree of individuals is always equal to the number of topology. In the stable state, the out-degrees of individuals distribute around the value of the number of topology K, except that the out-degree of a single individual is approximately double the out-degrees of the other individuals. In addition, under different initial conditions, some features of different kinds of networks emerge from the model. We also find the leader and herd mentality effects in the characteristics of the behaviors of human beings in our model. Thus, this work could be used to discover how to promote the emergence of beneficial group behaviors and prevent the emergence of harmful behaviors.

Hybrid Magnetoelectric Nanowires for Nanorobotic Applications: Fabrication, Magnetoelectric Coupling, and Magnetically Assisted In Vitro Targeted Drug Delivery.

An FeGa@P(VDF-TrFE) wire-shaped magnetoelectric nanorobot is designed and fabricated to demonstrate a proof-of-concept integrated device, which features wireless locomotion and on-site triggered therapeutics with a single external power source (i.e., a magnetic field). The device can be precisely steered toward a targeted location wirelessly by rotating magnetic fields and perform on-demand magnetoelectrically assisted drug release to kill cancer cells.

3D Printed Microtransporters: Compound Micromachines for Spatiotemporally Controlled Delivery of Therapeutic Agents.

Functional compound micromachines are fabricated by a design methodology using 3D direct laser writing and selective physical vapor deposition of magnetic materials. Microtransporters with a wirelessly controlled Archimedes screw pumping mechanism are engineered. Spatiotemporally controlled collection, transport, and delivery of micro particles, as well as magnetic nanohelices inside microfluidic channels are demonstrated.