Atomically precise engineering of spin-orbit polarons in a kagome magnetic Weyl semimetal.

Atomically precise defect engineering is essential to manipulate the properties of emerging topological quantum materials for practical quantum applications. However, this remains challenging due to the obstacles in modifying the typically complex crystal lattice with atomic precision. Here, we report the atomically precise engineering of the vacancy-localized spin-orbit polarons in a kagome magnetic Weyl semimetal Co3Sn2S2, using scanning tunneling microscope. We achieve the step-by-step repair of the selected vacancies, leading to the formation of artificial sulfur vacancies with elaborate geometry. We find that that the bound states localized around these vacancies undergo a symmetry dependent energy shift towards Fermi level with increasing vacancy size. As the vacancy size increases, the localized magnetic moments of spin-orbit polarons become tunable and eventually become itinerantly negative due to spin-orbit coupling in the kagome flat band. These findings provide a platform for engineering atomic quantum states in topological quantum materials at the atomic scale.

Discovery and construction of surface kagome electronic states induced by p-d electronic hybridization in Co3Sn2S2.

Kagome-lattice materials possess attractive properties for quantum computing applications, but their synthesis remains challenging. Herein, based on the compelling identification of the two cleavable surfaces of Co3Sn2S2, we show surface kagome electronic states (SKESs) on a Sn-terminated triangular Co3Sn2S2 surface. Such SKESs are imprinted by vertical p-d electronic hybridization between the surface Sn (subsurface S) atoms and the buried Co kagome-lattice network in the Co3Sn layer under the surface. Owing to the subsequent lateral hybridization of the Sn and S atoms in a corner-sharing manner, the kagome symmetry and topological electronic properties of the Co3Sn layer is proximate to the Sn surface. The SKESs and both hybridizations were verified via qPlus non-contact atomic force microscopy (nc-AFM) and density functional theory calculations. The construction of SKESs with tunable properties can be achieved by the atomic substitution of surface Sn (subsurface S) with other group III-V elements (Se or Te), which was demonstrated theoretically. This work exhibits the powerful capacity of nc-AFM in characterizing localized topological states and reveals the strategy for synthesis of large-area transition-metal-based kagome-lattice materials using conventional surface deposition techniques.

Nanoscale Manipulation of Wrinkle-Pinned Vortices in Iron-Based Superconductors.

The controlled manipulation of Abrikosov vortices is essential for both fundamental science and logical applications. However, achieving nanoscale manipulation of vortices while simultaneously measuring the local density of states within them remains challenging. Here, we demonstrate the manipulation of Abrikosov vortices by moving the pinning center, namely one-dimensional wrinkles, on the terminal layers of Fe(Te,Se) and LiFeAs, by utilizing low-temperature scanning tunneling microscopy/spectroscopy (STM/S). The wrinkles trap the Abrikosov vortices induced by the external magnetic field. In some of the wrinkle-pinned vortices, robust zero-bias conductance peaks are observed. We tailor the wrinkle into short pieces and manipulate the wrinkles by using an STM tip. Strikingly, we demonstrate that the pinned vortices move together with these wrinkles even at high magnetic field up to 6 T. Our results provide a universal and effective routine for manipulating wrinkle-pinned vortices and simultaneously measuring the local density of states on the iron-based superconductor surfaces.

Structure Characterization and Anti-Inflammatory Activity of Polysaccharides from Lingzhi or Reishi Medicinal Mushroom Ganoderma lucidum (Agaricomycetes) by Microwave-Assisted Freeze-Thaw Extraction.

A water-soluble polysaccharide (GLP-2) was isolated and purified from Ganoderma lucidum by the microwave-assisted freeze-thaw method. Microwave-assisted rapid thawing treatment can greatly improve the extraction yield of polysaccharides. The chemical structure of GLP-2 was analyzed with FT-IR, HPLC, GC-MS, and NMR spectrometry. It was proved that GLP-2 is mainly composed of ß-1,3-glucose and ß-1,6-glucose. The chain conformation of GLP-2 was analyzed by SEC-MALLS-RI, indicating that GLP-2 adopts semi-rigid chain conformation. Its molecular weight is 16.7 × 104, and its molecular size is about 61.2 nm. MTT assay indicated that GLP-2 was non-toxic to RAW 264.7 cells in vitro. The results of anti-inflammatory studies showed that GLP-2 can inhibit the production of NO, TNF-α, IL-1ß, and IL-6 in RAW 264.7 macrophage stimulated by lipopolysaccharide (LPS). The above data showed that the extraction method used in this study can obtain a high-yield polysaccharide with anti-inflammatory activity.

Roton pair density wave in a strong-coupling kagome superconductor.

The transition metal kagome lattice materials host frustrated, correlated and topological quantum states of matter1-9. Recently, a new family of vanadium-based kagome metals, AV3Sb5 (A = K, Rb or Cs), with topological band structures has been discovered10,11. These layered compounds are nonmagnetic and undergo charge density wave transitions before developing superconductivity at low temperatures11-19. Here we report the observation of unconventional superconductivity and a pair density wave (PDW) in CsV3Sb5 using scanning tunnelling microscope/spectroscopy and Josephson scanning tunnelling spectroscopy. We find that CsV3Sb5 exhibits a V-shaped pairing gap Δ ~ 0.5 meV and is a strong-coupling superconductor (2Δ/kBTc ~ 5) that coexists with 4a0 unidirectional and 2a0 × 2a0 charge order. Remarkably, we discover a 3Q PDW accompanied by bidirectional 4a0/3 spatial modulations of the superconducting gap, coherence peak and gap depth in the tunnelling conductance. We term this novel quantum state a roton PDW associated with an underlying vortex-antivortex lattice that can account for the observed conductance modulations. Probing the electronic states in the vortex halo in an applied magnetic field, in strong field that suppresses superconductivity and in zero field above Tc, reveals that the PDW is a primary state responsible for an emergent pseudogap and intertwined electronic order. Our findings show striking analogies and distinctions to the phenomenology of high-Tc cuprate superconductors, and provide groundwork for understanding the microscopic origin of correlated electronic states and superconductivity in vanadium-based kagome metals.

Observation of magnetic adatom-induced Majorana vortex and its hybridization with field-induced Majorana vortex in an iron-based superconductor.

Braiding Majorana zero modes is essential for fault-tolerant topological quantum computing. Iron-based superconductors with nontrivial band topology have recently emerged as a surprisingly promising platform for creating distinct Majorana zero modes in magnetic vortices in a single material and at relatively high temperatures. The magnetic field-induced Abrikosov vortex lattice makes it difficult to braid a set of Majorana zero modes or to study the coupling of a Majorana doublet due to overlapping wave functions. Here we report the observation of the proposed quantum anomalous vortex with integer quantized vortex core states and the Majorana zero mode induced by magnetic Fe adatoms deposited on the surface. We observe its hybridization with a nearby field-induced Majorana vortex in iron-based superconductor FeTe0.55Se0.45. We also observe vortex-free Yu-Shiba-Rusinov bound states at the Fe adatoms with a weaker coupling to the substrate, and discover a reversible transition between Yu-Shiba-Rusinov states and Majorana zero mode by manipulating the exchange coupling strength. The dual origin of the Majorana zero modes, from magnetic adatoms and external magnetic field, provides a new single-material platform for studying their interactions and braiding in superconductors bearing topological band structures.

Localized spin-orbit polaron in magnetic Weyl semimetal Co3Sn2S2.

The kagome lattice Co3Sn2S2 exhibits the quintessential topological phenomena of a magnetic Weyl semimetal such as the chiral anomaly and Fermi-arc surface states. Probing its magnetic properties is crucial for understanding this correlated topological state. Here, using spin-polarized scanning tunneling microscopy/spectroscopy (STM/S) and non-contact atomic force microscopy (nc-AFM) combined with first-principle calculations, we report the discovery of localized spin-orbit polarons (SOPs) with three-fold rotation symmetry nucleated around single S-vacancies in Co3Sn2S2. The SOPs carry a magnetic moment and a large diamagnetic orbital magnetization of a possible topological origin associated relating to the diamagnetic circulating current around the S-vacancy. Appreciable magneto-elastic coupling of the SOP is detected by nc-AFM and STM. Our findings suggest that the SOPs can enhance magnetism and more robust time-reversal-symmetry-breaking topological phenomena. Controlled engineering of the SOPs may pave the way toward practical applications in functional quantum devices.

Nearly quantized conductance plateau of vortex zero mode in an iron-based superconductor.

Majorana zero modes (MZMs) are spatially localized, zero-energy fractional quasiparticles with non-Abelian braiding statistics that hold promise for topological quantum computing. Owing to the particle-antiparticle equivalence, MZMs exhibit quantized conductance at low temperature. By using variable-tunnel-coupled scanning tunneling spectroscopy, we studied tunneling conductance of vortex bound states on FeTe0.55Se0.45 superconductors. We report observations of conductance plateaus as a function of tunnel coupling for zero-energy vortex bound states with values close to or even reaching the 2e 2/h quantum conductance (where e is the electron charge and h is Planck's constant). By contrast, no plateaus were observed on either finite energy vortex bound states or in the continuum of electronic states outside the superconducting gap. This behavior of the zero-mode conductance supports the existence of MZMs in FeTe0.55Se0.45.

Chrysophanol exhibits anti-cancer activities in lung cancer cell through regulating ROS/HIF-1a/VEGF signaling pathway.

In the present study, we explored the anti-tumor and anti-angiogenesis effects of chrysophanol, and to investigate the underlying mechanism of the chrysophanol on anti-tumor and anti-angiogenesis in human lung cancer. The viability of cells was measured by CCK-8 assay, cell apoptosis was measured by Annexin-FITC/PI staining assay, and the cell migration and invasion were analyzed by wound-healing assay and transwell assay. ROS generation and mitochondrial membrane potential were analyzed by DCFH-DA probe and mitochondrial staining kit. Angiogenesis was analyzed by tube formation assay. The expression of CD31 was analyzed by immunofluorescence. The levels of proteins were measured by western blot assay. The anti-tumor effects of chrysophanol in vivo were detected by established xenograft mice model. In this study, we found that the cell proliferation, migration, invasion, tube formation, the mitochondrial membrane potential, and the expression of CD31 were inhibited by chrysophanol in a dose-dependent manner, but cell apoptotic ratios and ROS levels were increased by chrysophanol in a dose-dependent manner. Furthermore, the effects of chrysophanol on A549, H738, and HUVEC cell apoptotic rates were reversed by the ROS inhibitor NAC. Besides, the effects of chrysophanol on HUVEC cell tube formation were reversed by the HIF-1α inhibitor KC7F2 and the VEGF inhibitor axitinib in vitro. Moreover, tumor growth was reduced by chrysophanol, and the expression of CD31, CD34, and angiogenin was suppressed by chrysophanol in vivo. Our finding demonstrated that chrysophanol is a highly effective and low-toxic drug for inhibition of tumor growth especially in high vascularized lung cancer.

A low-temperature scanning probe microscopy system with molecular beam epitaxy and optical access.

A low-temperature ultra-high vacuum scanning probe microscopy (SPM) system with molecular beam epitaxy (MBE) capability and optical access was conceived, built, and tested in our lab. The design of the whole system is discussed here, with special emphasis on some critical parts. The SPM scanner head takes a modified Pan-type design with improved rigidity and compatible configuration to optical access and can accommodate both scanning tunneling microscope (STM) tips and tuning-fork based qPlus sensors. In the system, the scanner head is enclosed by a double-layer cold room under a bath type cryostat. Two piezo-actuated focus-lens stages are mounted on both sides of the cold room to couple light in and out. The optical design ensures the system's forward compatibility to the development of photo-assisted STM techniques. To test the system's performance, we conducted STM and spectroscopy studies. The herringbone reconstruction and atomic structure of an Au(111) surface were clearly resolved. The dI/dV spectra of an Au(111) surface were obtained at 5 K. In addition, a periodic 2D tellurium (Te) structure was grown on the Au(111) surface using MBE and the atomic structure is clearly resolved by using STM.

RETRACTED: Physcion 8-O-ß-glucopyranoside inhibits clear-cell renal cell carcinoma bydownregulating hexokinase II and inhibiting glycolysis.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief and the authors. Panels from Figure 2A appear similar to panels from Figure 3A of the article published by Xiangyang Dou, Meihua Wang, Tao Zhang and Jiapei Yao in The Anatomical Record (2019) https://doi.org/10.1002/ar.24324, Figures 2B and 6B of the article published by C.-L. Xue, H.-G. Liu, B.-Y. Li, S.-H. He and Q.-F. Yue in the Eur. Rev. Med. Pharmacol. Sci. 23 (2019) 5101-5112 https://doi.org/10.26355/eurrev_201906_18174 and Figure 3B of the article published by Bo Liu and Shuo Yu in Biomedicine & Pharmacotherapy 107 (2018) 243-253 https://doi.org/10.1016/j.biopha.2018.07.177. Panels from Figure 6D appear similar to panels from Figure 8D of the article published by The Anatomical Record (2019) https://doi.org/10.1002/ar.24324, Figure 7E of the article published by Ying Niu, Jinping Zhang, Yalin Tong, Jiansheng Li and Bingrong Liu in Life Sciences 237 (2019) 116893 https://doi.org/10.1016/j.lfs.2019.116893 and Figure 7F of the article published by Xiaoping Pan, Chen Wang, Yan Li, Lida Zhu and Ti Zhang in Life Sciences 214 (2018) 124-135 https://doi.org/10.1016/j.lfs.2018.10.064. Although this article was published earlier than the other articles, the Editor decided to retract this article given concerns about the reliability of the data.

Physcion 8-O-ß-glucopyranoside induces apoptosis, suppresses invasion and inhibits epithelial to mesenchymal transition of hepatocellular carcinoma HepG2 cells.

BACKGROUND: Aberrant increased expression of DNMT1 and resulting silence of tumor suppressor genes have been found in a variety of human malignancies and DNMT1 has been considered as a promising therapeutic target for cancer prevention and treatment. One of the main active ingredients of Rumex japonicus Houtt, physcion 8-O-ß-glucopyranoside (PG), has been found to have antitumor activities. MATERIALS AND METHODS: Human hepatocellular carcinoma (HCC) cell line HepG2 was examined. Cell proliferation was analyzed using MTT assay. The apoptosis, migration and invasion were determined by flow cytometry, wound healing and Transwell assay, respectively. The expression of signaling molecules were examined by RT-PCR and western blots. RESULTS: Our results provide experimental evidence that PG inhibits growth and suppresses invasion of HCC cells by downregulating DNMT1 via ROS-dependent AMP-activated protein kinase (AMPK)-mediated modulation of transcription factor Sp1. CONCLUSION: our results revealed for the first time that PG inhibits growth and suppresses invasion of HCC, highlighting the anti-tumor activities of PG against HCC. However, further studies, including clinical trials, are needed to fully evaluate PG as a novel therapeutic in cancer prevention and treatment.

Effects of Feijining Decoction on vascular endothelial growth factor protein expression and changes of T cell subsets in Lewis lung carcinoma-bearing mice.

Angiogenesis is crucial for cancer growth and metastasis. T cells are also key members of the adaptive immunity against tumorigenesis. The aim of the present study was to observe the effects of Feijining Decoction (FJND) on vascular endothelial growth factor (VEGF) protein expression and T cell subsets [cluster of differentiation 4+(CD4+) and CD8+ T lymphocyte] in Lewis lung carcinoma (LLC)-bearing mice. C57BL/6J mice were subcutaneously implanted with LLC cells. Forty carcinoma-bearing mice were randomly assigned to four groups (10 animals/group). The control group (CG) were the untreated group, the cisplatinum (DDP) group (DG) mice were treated with DDP, the FJND group (FG) were treated with FJND and the FJND + DDP group (FDG) were treated with FJND and DDP. Western blot and flow cytometry were used to evaluate the VEGF protein expression of tumor tissue and T cell subsets of the spleen. Spontaneous activity in 5 min was observed by the photoelectric counting method. DDP + FJND (FDG group) markedly inhibited tumor growth compared to the DG mice. The protein expression of VEGF was significantly downregulated in the carcinoma of FG mice compared to CG mice. VEGF protein expression was significantly reduced in FDG compared to DG mice. In the FG mice, the splenic CD4+ and CD4+/CD8+ cells were significantly increased compared to the CG mice, and the splenic CD4+ cells in the FDG mice were significantly increased compared to the DG group. In conclusion, FJND can inhibit tumor growth by downregulating VEGF protein expression and improving the immune function.

Environmentally responsive histidine-carboxylate zipper formation between proteins and nanoparticles.

Interfacing synthetic materials with biomacromolecules provides new systems for biological applications. We report the creation of a reversible multivalent supramolecular "zipper" recognition motif between gold nanoparticles and proteins. In this assembly, carboxylate-functionalized nanoparticles interact strongly with oligohistidine tags. This interaction can be tuned through His-tag length, and offers unique binding profiles based on the pH and electrolyte concentration of the medium.

The role of surface functionality in nanoparticle exocytosis.

Getting out is just as important for nano-therapeutics as getting in. Exocytosis rates determine residency time in the cell, an important determinant for therapeutic efficacy and also for eventual clearance from the cell. In this study, it is shown that exocytosis efficiency is determined by surface functionality, providing a strategy for optimizing nanocarriers.

Multiplexed imaging of nanoparticles in tissues using laser desorption/ionization mass spectrometry.

Imaging of nanomaterials in biological tissues provides vital information for the development of nanotherapeutics and diagnostics. Multiplexed imaging of different nanoparticles (NPs) greatly reduces costs, the need to use multiple animals, and increases the biodistribution information that can enhance diagnostic applications and accelerate the screening of potential therapeutics. Various approaches have been developed for imaging NPs; however, the readout of existing imaging techniques relies on specific properties of the core material or surface ligands, and these techniques are limited because of the relatively small number of NPs that can be simultaneously measured in a single experiment. Here, we demonstrate the use of laser desorption/ionization mass spectrometry (LDI-MS) in an imaging format to investigate surface chemistry dictated intraorgan distribution of NPs. This new LDI-MS imaging method enables multiplexed imaging of NPs with potentially unlimited readouts and without additional labeling of the NPs. It provides the capability to detect and image attomole levels of NPs with almost no interferences from biomolecules. Using this new imaging approach, we find that the intraorgan distributions of same-sized NPs are directly linked to their surface chemistry.