Anyon is collective excitation of two dimensional electron gas subjected to strong magnetic field, carrying fractional charges and exotic statistical character beyond fermion and boson. So far, ...anyons with serial fractional charges only exist in fractional quantum Hall effect. It is still a challenge to find new serial of fractional charges in other physical system and develop an unified mathematical physics theory based on the same root. Here a topological path fusion theory of propagating electrons in magnetic flux lattice is proposed to explore the physical origin of fractional charges based on a generalization of Feynman's path integral theory and Thurston's train track theory. This mathematical physics theory generated the existed serial of fractional charges in fractional quantum Hall effect and predicted new serial of fractional charges. A serial of irrational charges are predicted in one dimensional lattice of magnetic fluxes. Fractionally charged anyons are also generated in two dimensional and three dimensional lattice of train tracks of electric currents, revealing an exact correspondence between knot lattice model and train track model. A new explanation for the modular symmetry of complex Hall conductance and composite fermion in fractional quantum Hall effect is also derived from this topological path fusion theory. Experimental observation of anyon in three dimensions can be realized by constructing three dimensional interlocking magnetic fluxes or mapping magnetic fluxes into forbidden zones in multi-connected space filled by solid state material. A photonic crystal with porous nano-structures is a promising system for detecting fractional charges and paves a new way for topological quantum computation.
The combination of bottom‐up controllable self‐assembly technique with bioinspired design has opened new horizons in the development of self‐propelled synthetic micro/nanomotors. Over the past five ...years, a significant advances toward the construction of bioinspired self‐propelled micro/nanomotors has been witnessed based on the controlled self‐assembly technique. Such a strategy permits the realization of autonomously synthetic motors with engineering features, such as sizes, shapes, composition, propulsion mechanism, and function. The construction, propulsion mechanism, and movement control of synthetic micro/nanomotors in connection with controlled self‐assembly in recent research activities are summarized. These assembled nanomotors are expected to have a tremendous impact on current artificial nanomachines in future and hold potential promise for biomedical applications including drug targeted delivery, photothermal cancer therapy, biodetoxification, treatment of atherosclerosis, artificial insemination, crushing kidney stones, cleaning wounds, and removing blood clots and parasites.
Bioinspired self‐propelled nanomotors based on controlled molecular self‐assembly permit the achievement of autonomously synthetic micro/nanomotors with engineering features, such as sizes, shapes, composition, propulsion mechanism, and function. Recent progress toward the construction, propulsion strategy, and movement regulation of controllable self‐assembled micro/nanomotors is summarized. Such assembled motors hold considerable promise in performing various tasks and diverse applications.
We report a fuel-free, near-infrared （NIR）-driven Janus microcapsule motor. The Janus microcapsule motors were fabricated by template-assisted polyelectrolyte layer-by-layer assembly, followed by ...spraying of a gold layer on one side. The NIR-powered Janus motors achieved high propulsion with a maximum speed of 42μm.s-1 in water. The propulsion mechanism of the Janus motor was attributed to the self-thermophoresis effect： The asymmetric distribution of the gold layer generated a local thermal gradient, which in turn generated thermophoretic force to propel the Janus motor. Such NIR-propelled Janus capsule motors can move efficiently in cell culture medium and have no obvious effects on the cell at the power of the NIR laser, indicating considerable promise for future biomedical applications.
Photothermal therapy based on gold nanostructures has been widely investigated as a state‐of‐the‐art noninvasive therapy approach. Because single nanoparticles cannot harvest sufficient energy, ...self‐assemblies of small plasmonic particles into large aggregates are required for enhanced photothermal performance. Self‐assembled gold nanorods in lipid bilayer‐modified microcapsules are shown to localize at tumor sites, generate vapor bubbles under near‐infrared light exposure, and subsequently damage tumor tissues. The polyelectrolyte multilayer enables dense packing of gold nanorods during the assembly process, which leads to the formation of vapor bubbles around the excited capsules. The resulting vapor bubbles achieve a high efficiency of suppressing tumor growth compared to single gold nanorods. In vivo experiments demonstrated the ability of soft‐polymer multilayer microcapsules to cross the biological barriers of the body and localize at target tissues.
Antitumor bubbles: A photothermal theranostic platform based on biocompatible gold nanorod‐assembled capsules was demonstrated with good deformability behavior and behavior similar to red blood cells. The resulting vapor bubbles, induced by a cumulative thermal effect between adjacent gold nanorods, can locally damage tumor cells and enable photothermal therapy with high efficacy compared to single gold nanorods.
Many species of bacteria can spread over a moist surface via a particular form of collective motion known as “surface swarming”. This form of motility is typically studied by inoculating bacteria on ...a gel formed by 0.4–1.5% agar, which contains essential nutrients for their growth and proliferation. Using Pseudomonas aeruginosa and its pili-less mutant, ΔPilA, we investigate physical factors that either facilitate or restrict the swarming motility, measured by the rate of increase in area covered by a spreading bacterial colony, i.e., a swarm. The wild-type colony spreads over the agar surface in highly branched structures. The pili-less mutant fills up the area more fully as it spreads, but it also produces numerous and fragmented branches, or tendrils, at the swarm front. Whereas additional surfactants enhance swarming, increasing the agar percentage, adding extra salt or sugar or incorporating viscous agents in the agar matrix all decrease swarming, supporting the conclusion that swarming motility is restricted by the surface tension at the swarm front and swarm growth is limited by the rate of water supply from within the agar gel. The physical basis elaborated through this study provides a useful framework for understanding the swarming behavior of numerous species of bacteria.
Inspired by biological microorganisms swimming in circles in liquid with low Reynolds number, I developed the dynamic theory for computing the helical trajectory of a circling particle with an ...overdamped circle center. The equation of motion for the circling particle is a hybrid equation of deterministic terms and stochastic terms. Observing the motion of a swimming microorganism, I found the strength of stochastic fluctuations should be much smaller than that governs deterministic dynamics. This dynamic theory predicts a nonlinear transverse motion perpendicular to the direction of external force. Both the living microorganism and artificial circling particle are applicable for an experimental check of this prediction. For the convenience of easy theoretical research, I further derived the probability conservation equations based on this dynamic theory both in two-dimensional and three-dimensional space.
► Develop the dynamic equation of a circling particle with overdamped circle center. ► A force in one direction induces a motion perpendicular to this direction. ► Derive the equation for the probability distribution of a circling particle.
Self-propelled micro/nanomotors possess tremendous exciting promise in diverse fields. We describe an asymmetric, fuel-free and near-infrared light-powered torpedo micromotor, which is constructed by ...using a porous membrane-assisted layer-by-layer sol-gel method to form silica multilayer inside the pores, following by the deposition of gold nanoparticles on one end of the pores. In the absence of chemical fuels, the high propulsion of microtorpedoes under illumination of near-infrared light is owing to the photo-thermal effect of gold clusters, generating a thermal gradient inside the microtorpedoes. The speed of microtorpedoes is dependent on the laser powers and media. More interestingly, such fuel free-powered microtorpedoes could explode triggered by higher laser power at the predefined site and thus provide a new platform for future biomedical applications.
It is a long-standing challenge to accomplish bionic microrobot that acts in a similar way of white blood cell, chasing bacteria in complex environment. Without an effective external control field, ...most swarming microrobots systems are usually unable to perform directional movement and redirect their motion to capture the target. Here we report the predatory-prey dynamics of self-propelled clusters of Janus micromotors. The active cluster generates an oxygen bubbles cloud around itself by decomposing H2O2, which levitated it above the substrate, enhancing its mobility in solution to wander around to devour other clusters. The fast decomposition of H2O2 also induced a tubular low-concentration zone that bridges two clusters far separated from each other, resulting in a diffusio-osmotic pressure that drives the two clusters to meet. This predatory-prey phenomena mimic white blood cells chasing bacteria and swarming flocks in nature, shedding light on emergent collective intelligence in biology.
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•We synthesized self-propelled clusters of swarming Janus micromotors•A self-propelled cluster of swarming Janus micromotors predates another cluster•The cluster confined to the substrate surface moves much faster than that in bulk solution
Surface chemistry; Robotics; Devices
•We proposed a new pairing theory between boson and fermion in optical superlatice.•Stable pairing states only exist in discrete momentum vector zones, which are connected by chiral linear ...mode.•Different stable pairing states are classified by topological numbers.•Critical temperature of gapped-to-gapless phase transition shows similar trend as that of high Tc superconductor.
A convective pairing mode of a boson-fermion mixture of ultracold atoms confined in an optical superlattice can be induced by the transformation between two optical superlattice configurations. This convective pairing mode only exists in discrete momentum vector zones for pairing energy gaps. The energy spectrum of gapped states is characterized by topological winding numbers. Two neighboring gapped states are bridged by an unstable chiral linear mode, which drives the boson-fermion pair into directional motion for a short period but remains static in the supersymmetric phase with time-reversal symmetry. The phase transition from a gapped mode to a gapless mode occurs at a critical temperature, whose distribution curve for chemical potential demonstrates a similar dome-like trend as that of high Tc superconductor. The boson-fermion pairing may shed light on a possible mechanism of high-Tc superconductivity.
We established a large class of exactly soluble spin liquids and chiral spin liquids on three-dimensional helix lattices by introducing Kitaev-type's spin coupling. In the chiral spin liquids, exact ...stable ground states with spontaneous breaking of the time reversal symmetry are found. The fractionalized loop excitations in both the spin and chiral spin liquids obey non-Abelian statistics. We characterize this kind of statistics by non-Abelian Berry phase and quantum algebra relation. The topological correlation of loops is independent of local order parameter and it measures the intrinsic global quantum entanglement of degenerate ground states.
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