Topological Atomic Spinwave Lattices by Dissipative Couplings

Recent experimental advance in creating dissipative couplings provides a new route for engineering exotic lattice systems and exploring topological dissipation. Using the spatial lattice of atomic spinwaves in a vacuum vapor cell, where purely dissipative couplings arise from diffusion of atoms, we experimentally realize a dissipative version of the Su-Schrieffer-Heeger (SSH) model. We construct the dissipation spectra of the topological or trivial lattices via electromagnetically-induced-transparency (EIT) spectroscopy. The topological dissipation spectrum is found to exhibit edge modes at dissipation rates within a dissipative gap, decoupled from the bulk. We also validate chiral symmetry of the dissipative SSH couplings. This work paves the way for realizing topology-enabled quantum correlations and non-Hermitian topological quantum optics via dissipative couplings.Comment: 5 pages, 4 figure

Signature of coexistence of superconductivity and ferromagnetism in two-dimensional NbSe\u3csub\u3e2\u3c/sub\u3e triggered by surface molecular adsorption

Ferromagnetism is usually deemed incompatible with superconductivity. Consequently, the coexistence of superconductivity and ferromagnetism is usually observed only in elegantly designed multi-ingredient structures in which the two competing electronic states originate from separate structural components. Here we report the use of surface molecular adsorption to induce ferromagnetism in two-dimensional superconducting NbSe2, representing the freestanding case of the coexistence of superconductivity and ferromagnetism in one two-dimensional nanomaterial. Surface-structural modulation of the ultrathin superconducting NbSe2 by polar reductive hydrazine molecules triggers a slight elongation of the covalent Nb–Se bond, which weakens the covalent interaction and enhances the ionicity of the tetravalent Nb with unpaired electrons, yielding ferromagnetic ordering. The induced ferromagnetic momentum couples with conduction electrons generating unique correlated effects of intrinsic negative magnetoresistance and the Kondo effect. We anticipate that the surface molecular adsorption will be a powerful tool to regulate spin ordering in the two-dimensional paradigm

Natural products in digestive tract tumors metabolism: Functional and application prospects

Digestive tract diseases are presently the hotspot of clinical diagnosis and treatment, and the incidence of digestive tract tumor is increasing annually. Surgery remains the main therapeutic schedule for digestive tract tumor. Though benefits were brought by neoadjuvant chemotherapy, a part of patients lose the chance of surgery because of late detection or inappropriate intervention. Therefore, the treatment of inoperable patients has become an urgent need. At the same time, tumor metabolism is an extremely complex and diverse process. Natural products are confirmed effective to inhibit the development of tumors in vitro and in vitro. There are many kinds of natural products and their functions remain not clear. However, some natural products such as polyphenols have been proven to have definite anti-cancer effects, and some terpenoids have definite anti-inflammatory, anti-ulcer, anti-tumor, and other effects. Therefore, the anti-tumor characteristics of natural products should arouse our high attention. Although there are many obstacles to study the activities of natural products in tumor, including the difficulty in detection or distinguishing each component due to their low levels in tumor tissue, etc., the emergence of highly sensitive and locatable spatial metabolomics make the research and application of natural products a big step forward. In this review, natural products such as phenols, terpenoids and biotinoids were summarized to further discuss the development and therapeutic properties of natural metabolites on digestive tract tumors

An algorithm to evaluate implementation cost for liveness-enforcing supervisors designed by deadlock prevention policy

Deadlock prevention policy is widely used to design the liveness-enforcing supervisors because of its advantage that deadlocks are considered and solved in design and planning stages for flexible manufacturing systems modeled with Petri nets. However, how to evaluate the implementation cost of these liveness-enforcing supervisors is not done in the existing literature. This article proposes an algorithm to evaluate the implementation cost performance of different liveness-enforcing supervisors designed by deadlock prevention policy. By designing a multiple objective linear programming problem associated with two parameters (denoted as f 1 and f 2 ) to characterize the corresponding implementation costs for the added control places and the related input and out transitions and control arcs, the proposed algorithm first obtains the variable regions of f 1 and f 2 And then a satisfactory level coefficient (denoted as λ ) concentrating on the optimal compromise solutions of f 1 and f 2 (denoted as f 1 * and f 2 * ) is solved by a linear programming problem. As a result, the implementation cost performance of the corresponding liveness-enforcing supervisor can be indicated conveniently on the basis of the values of λ , f 1 * , and f 2 * . The practical potential of the proposed algorithm is demonstrated via a theoretical analysis and several widely used examples from the existing literature

Signature of coexistence of superconductivity and ferromagnetism in two-dimensional NbSe\u3csub\u3e2\u3c/sub\u3e triggered by surface molecular adsorption

Ferromagnetism is usually deemed incompatible with superconductivity. Consequently, the coexistence of superconductivity and ferromagnetism is usually observed only in elegantly designed multi-ingredient structures in which the two competing electronic states originate from separate structural components. Here we report the use of surface molecular adsorption to induce ferromagnetism in two-dimensional superconducting NbSe2, representing the freestanding case of the coexistence of superconductivity and ferromagnetism in one two-dimensional nanomaterial. Surface-structural modulation of the ultrathin superconducting NbSe2 by polar reductive hydrazine molecules triggers a slight elongation of the covalent Nb–Se bond, which weakens the covalent interaction and enhances the ionicity of the tetravalent Nb with unpaired electrons, yielding ferromagnetic ordering. The induced ferromagnetic momentum couples with conduction electrons generating unique correlated effects of intrinsic negative magnetoresistance and the Kondo effect. We anticipate that the surface molecular adsorption will be a powerful tool to regulate spin ordering in the two-dimensional paradigm

A feasible interlayer strategy for simultaneous light and heat management in photothermal catalysis

Summary: Photothermal conversion represents one crucial approach for solar energy harvesting and its exploitation as a sustainable alternative to fossil fuels; however, an efficient, cost-effective, and generalized approach to enhance the photothermal conversion processes is still missing. Herein, we develop a feasible and efficient photothermal conversion strategy that achieves simultaneous light and heat management using supported metal clusters and WSe2 interlayer toward enhanced CO2 hydrogenation photothermal catalysis. The interlayer can simultaneously reduce heat loss in the catalytic layer and improve light absorption, leading to an 8-fold higher CO2 conversion rate than the controls. The optical and thermal performance of WSe2 interlayered catalysts on different substrates was quantified using Raman spectroscopy. This work demonstrates a feasible and generalized approach for effective light and heat management in solar harvesting. It also provides important design guidelines for efficient photothermal converters that facilitate the remediation of the energy and environmental crises faced by humans

Nanoladders Facilitate Directional Axonal Outgrowth and Regeneration

After injuries, axonal regeneration over long distance is challenging due to lack of orientation guidance. Biocompatible scaffolds have been used to mimic the native organization of axons to guide and facilitate axonal regeneration. Those scaffolds are of great importance in achieving functional connections of the nervous system. We have developed a nanoladder scaffold to guide directional outgrowth and facilitate regeneration of axons. The nanoladders, composed of micron-scale stripes and nanoscale protrusions, were fabricated on the glass substrate using photolithography and reactive ion etching methods. Embryonic neurons cultured on the nanoladder scaffold showed significant neurite elongation and axonal alignment in parallel with the nanoladder direction. Furthermore, the nanoladders promoted axonal regeneration and functional connection between organotypic spinal cord slices over 1 mm apart. Multimodality imaging studies revealed that such neuronal regeneration was supported by directional outgrowth of glial cells along nanoladders in the organotypic spinal cord slice culture as well as in the coculture of glial cells and neurons. These results collectively herald the potential of our nanoladder scaffold in facilitating and guiding neuronal development and functional restoration