Publications by authors named "Shao-Chun Li"

48 Publications

Anomalous Superconducting Proximity Effect in Bi Se /FeSe Te Thin-Film Heterojunctions.

Adv Mater 2021 Nov 24:e2107799. Epub 2021 Nov 24.

National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.

Superconducting proximity effect (SPE) induces superconductivity transition in the otherwise non superconducting thin-film in proximity with a superconductor. The SPE usually occurs in real space and decays exponentially with the film thickness. Herein, we unveiled an abnormal SPE in a topological insulator (TI)/superconductor heterostructure, which is attributed to the topologically protected surface state. Surprisingly, such abnormal SPE occurs in momentum space regardless the TI film thickness, as long as the topological surface states are robust and form a continuous conduction loop. Combining transport measurements and scanning tunneling microscopy/spectroscopy techniques, we explored the SPE in Bi Se /FeSe Te heterostructures, where Bi Se is an ideal three-dimensional topological insulator and FeSe Te a typical iron-based superconductor. As the thickness of the Bi Se thin-film exceeds 400 nanometers, there still exits SPE-induced superconductivity on the surface of Bi Se thin-film with a transition temperature T not less than 10 K. Such an extraordinary behavior is induced by the unique properties of topologically protected surface states of Bi Se . This research will deepen the understanding of important role of topologically protected surface states in the SPE. This article is protected by copyright. All rights reserved.
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http://dx.doi.org/10.1002/adma.202107799DOI Listing
November 2021

Comparison of the real-world effectiveness of vertical versus lateral functional hemispherotomy techniques for pediatric drug-resistant epilepsy: A post hoc analysis of the HOPS study.

Epilepsia 2021 Nov 12;62(11):2707-2718. Epub 2021 Sep 12.

Division of Neurosurgery, Department of Surgery, BC Children's Hospital and University of British Columbia, Vancouver, British Columbia, Canada.

Objective: This study was undertaken to determine whether the vertical parasagittal approach or the lateral peri-insular/peri-Sylvian approach to hemispheric surgery is the superior technique in achieving long-term seizure freedom.

Methods: We conducted a post hoc subgroup analysis of the HOPS (Hemispheric Surgery Outcome Prediction Scale) study, an international, multicenter, retrospective cohort study that identified predictors of seizure freedom through logistic regression modeling. Only patients undergoing vertical parasagittal, lateral peri-insular/peri-Sylvian, or lateral trans-Sylvian hemispherotomy were included in this post hoc analysis. Differences in seizure freedom rates were assessed using a time-to-event method and calculated using the Kaplan-Meier survival method.

Results: Data for 672 participants across 23 centers were collected on the specific hemispherotomy approach. Of these, 72 (10.7%) underwent vertical parasagittal hemispherotomy and 600 (89.3%) underwent lateral peri-insular/peri-Sylvian or trans-Sylvian hemispherotomy. Seizure freedom was obtained in 62.4% (95% confidence interval [CI] = 53.5%-70.2%) of the entire cohort at 10-year follow-up. Seizure freedom was 88.8% (95% CI = 78.9%-94.3%) at 1-year follow-up and persisted at 85.5% (95% CI = 74.7%-92.0%) across 5- and 10-year follow-up in the vertical subgroup. In contrast, seizure freedom decreased from 89.2% (95% CI = 86.3%-91.5%) at 1-year to 72.1% (95% CI = 66.9%-76.7%) at 5-year to 57.2% (95% CI = 46.6%-66.4%) at 10-year follow-up for the lateral subgroup. Log-rank test found that vertical hemispherotomy was associated with durable seizure-free progression compared to the lateral approach (p = .01). Patients undergoing the lateral hemispherotomy technique had a shorter time-to-seizure recurrence (hazard ratio = 2.56, 95% CI = 1.08-6.04, p = .03) and increased seizure recurrence odds (odds ratio = 3.67, 95% CI = 1.05-12.86, p = .04) compared to those undergoing the vertical hemispherotomy technique.

Significance: This pilot study demonstrated more durable seizure freedom of the vertical technique compared to lateral hemispherotomy techniques. Further studies, such as prospective expertise-based observational studies or a randomized clinical trial, are required to determine whether a vertical approach to hemispheric surgery provides superior long-term seizure outcomes.
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http://dx.doi.org/10.1111/epi.17021DOI Listing
November 2021

Direct Growth of van der Waals Tin Diiodide Monolayers.

Adv Sci (Weinh) 2021 Oct 16;8(20):e2100009. Epub 2021 Aug 16.

National Laboratory of Solid State Microstructures and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.

Two-dimensional (2D) van der Waals (vdW) materials have garnered considerable attention for their unique properties and potentials in a wide range of fields, which include nano-electronics/optoelectronics, solar energy, and catalysis. Meanwhile, challenges in the approaches toward achieving high-performance devices still inspire the search for new 2D vdW materials with precious properties. In this study, via molecular beam epitaxy, for the first time, the vdW SnI monolayer is successfully fabricated with a new structure. Scanning tunneling microscopy/spectroscopy characterization, as corroborated by the density functional theory calculation, indicates that this SnI monolayer exhibits a band gap of ≈2.9 eV in the visible purple range, and an indirect- to direct-band gap transition occurs in the SnI bilayer. This study provides a new semiconducting 2D material that is promising as a building block in future electronics/optoelectronics.
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http://dx.doi.org/10.1002/advs.202100009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8529434PMC
October 2021

Uric acid is associated with cardiac death in patients with hypertrophic obstructive cardiomyopathy.

J Geriatr Cardiol 2021 Apr;18(4):281-288

Department of Cardiology and Institute of Vascular Medicine, Peking University Third Hospital, NHC Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, China.

Background: The role of uric acid (UA) in survival of patients with hypertrophic obstructive cardiomyopathy (HOCM) has not been fully evaluated. This study aimed to determine whether UA could be an independent risk factor of cardiac death in patients with HOCM.

Methods: A total of 317 patients with HOCM, who were receiving conservative treatment in Fuwai Hospital from October 2009 to December 2014, all of them completed UA evaluations, were analyzed. Patients were divided into three groups according to the UA levels: Tertile 1 (≤ 318 μmol/L, = 106), Tertile 2 (319 to 397 μmol/L, = 105), and Tertile 3 (≥ 398 μmol/L, = 106).

Results: During a median follow-up of 45 months, 29 cardiac deaths (9.1%) occurred, including 6 sudden cardiac deaths and 23 heart failure-related deaths. Cardiac death in Tertile 3 ( = 16, 55.2%) was significantly higher than in Tertile 1 ( = 6, 20.7%) and Tertile 2 ( = 7, 24.1%). In univariate model, UA level (continuous value) showed predictive value of cardiac death [hazard ratio (HR) = 1.006, 95% CI: 1.003-1.009, = 0.009]. Univariate Cox survival analysis had shown a significant higher property of cardiac death in patients of Tertile 3 when compared with those of Tertile 1, but cardiac death in patients of Tertile 2 did not show significant prognositic value compared with those of Tertile 1 (HR = 3.927, 95% CI: 0.666-23.162, = 0.131). UA was found to be an independent risk factor (HR = 1.005, 95% CI: 1.001-1.009, = 0.009) of cardiac death in the multivariate regression analysis after the adjustment for age, body mass index, atrial fibrillation, hemoglobin, creatinine, high-sensitivity C-reactive protein, interventricular septum/left ventricular posterior wall ratio, left ventricular outflow tract and left ventricular ejection fraction.

Conclusions: UA concentration was found to be independently associated with cardiac death in HOCM patients receiving conservative treatment. Randomized trials of UA-lowering agents for HOCM patients are warranted.
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http://dx.doi.org/10.11909/j.issn.1671-5411.2021.04.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8100422PMC
April 2021

Assessment of causal association between thyroid function and lipid metabolism: a Mendelian randomization study.

Chin Med J (Engl) 2021 Apr 13;134(9):1064-1069. Epub 2021 Apr 13.

Department of Cardiology, Peking University Third Hospital, Beijing 100191, China.

Background: Thyroid dysfunction is associated with cardiovascular diseases. However, the role of thyroid function in lipid metabolism remains partly unknown. The present study aimed to investigate the causal association between thyroid function and serum lipid metabolism via a genetic analysis termed Mendelian randomization (MR).

Methods: The MR approach uses a genetic variant as the instrumental variable in epidemiological studies to mimic a randomized controlled trial. A two-sample MR was performed to assess the causal association, using summary statistics from the Atrial Fibrillation Genetics Consortium (n = 537,409) and the Global Lipids Genetics Consortium (n = 188,577). The clinical measures of thyroid function include thyrotropin (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) levels, FT3:FT4 ratio and concentration of thyroid peroxidase antibodies (TPOAb). The serum lipid metabolism traits include total cholesterol (TC) and triglycerides, high-density lipoprotein, and low-density lipoprotein (LDL) levels. The MR estimate and MR inverse variance-weighted method were used to assess the association between thyroid function and serum lipid metabolism.

Results: The results demonstrated that increased TSH levels were significantly associated with higher TC (β = 0.052, P = 0.002) and LDL (β = 0.041, P = 0.018) levels. In addition, the FT3:FT4 ratio was significantly associated with TC (β = 0.240, P = 0.033) and LDL (β = 0.025, P = 0.027) levels. However, no significant differences were observed between genetically predicted FT4 and TPOAb and serum lipids.

Conclusion: Taken together, the results of the present study suggest an association between thyroid function and serum lipid metabolism, highlighting the importance of the pituitary-thyroid-cardiac axis in dyslipidemia susceptibility.
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http://dx.doi.org/10.1097/CM9.0000000000001505DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8116035PMC
April 2021

Hemispherectomy Outcome Prediction Scale: Development and validation of a seizure freedom prediction tool.

Epilepsia 2021 05 13;62(5):1064-1073. Epub 2021 Mar 13.

Department of Pediatrics, BC Children's Hospital and University of British Columbia, Vancouver, British Columbia, Canada.

Objective: To develop and validate a model to predict seizure freedom in children undergoing cerebral hemispheric surgery for the treatment of drug-resistant epilepsy.

Methods: We analyzed 1267 hemispheric surgeries performed in pediatric participants across 32 centers and 12 countries to identify predictors of seizure freedom at 3 months after surgery. A multivariate logistic regression model was developed based on 70% of the dataset (training set) and validated on 30% of the dataset (validation set). Missing data were handled using multiple imputation techniques.

Results: Overall, 817 of 1237 (66%) hemispheric surgeries led to seizure freedom (median follow-up = 24 months), and 1050 of 1237 (85%) were seizure-free at 12 months after surgery. A simple regression model containing age at seizure onset, presence of generalized seizure semiology, presence of contralateral 18-fluoro-2-deoxyglucose-positron emission tomography hypometabolism, etiologic substrate, and previous nonhemispheric resective surgery is predictive of seizure freedom (area under the curve = .72). A Hemispheric Surgery Outcome Prediction Scale (HOPS) score was devised that can be used to predict seizure freedom.

Significance: Children most likely to benefit from hemispheric surgery can be selected and counseled through the implementation of a scale derived from a multiple regression model. Importantly, children who are unlikely to experience seizure control can be spared from the complications and deficits associated with this surgery. The HOPS score is likely to help physicians in clinical decision-making.
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http://dx.doi.org/10.1111/epi.16861DOI Listing
May 2021

Ligand Non-innocence and Single Molecular Spintronic Properties of Ag Dibenzocorrole Radical on Ag(111).

Angew Chem Int Ed Engl 2021 May 16;60(21):11702-11706. Epub 2021 Apr 16.

State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Advanced Microstructures, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210046, P. R. China.

A facile method for the quantitative preparation of silver dibenzo-fused corrole Ag-1 is described. In contrast to the saddle conformation resolved by single-crystal X-ray analysis for Ag-1, it adopts an unprecedented domed geometry, with up and down orientations, when adsorbed on an Ag(111) surface. Sharp Kondo resonances near Fermi level, both at the corrole ligand and the silver center were observed by cryogenic STM, with relatively high Kondo temperature (172 K), providing evidence for a non-innocent Ag -corrole species. Further investigation validates that benzene ring fusion and molecule-substrate interactions play pivotal roles in enhancing Ag(4d(x -y ))-corrole (π) orbital interactions, thereby stabilizing the open-shell singlet Ag -corrole on Ag(111) surface. Moreover, this strategy used for constructing metal-free benzene-ring fused corrole ligand gives rise to inspiration of designing novel metal-corrole compound for multichannel molecular spintronics devices.
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http://dx.doi.org/10.1002/anie.202016674DOI Listing
May 2021

Kinetics-Limited Two-Step Growth of van der Waals Puckered Honeycomb Sb Monolayer.

ACS Nano 2020 Dec 1. Epub 2020 Dec 1.

National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China.

Puckered honeycomb Sb monolayer, the structural analog of black phosphorene, has been recently successfully grown by means of molecular beam epitaxy. However, little is known to date about the growth mechanism for such a puckered honeycomb monolayer. In this study, by using scanning tunneling microscopy in combination with first-principles density functional theory calculations, we unveil that the puckered honeycomb Sb monolayer takes a kinetics-limited two-step growth mode. As the coverage of Sb increases, the Sb atoms first form the distorted hexagonal lattice as the half layer, and then the distorted hexagonal half-layer transforms into the puckered honeycomb lattice as the full layer. These results provide the atomic-scale insight in understanding the growth mechanism of puckered honeycomb monolayer and can be instructive to the direct growth of other monolayers with the same structure.
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http://dx.doi.org/10.1021/acsnano.0c04620DOI Listing
December 2020

Thoracic Paravertebral Blockade Reduces Chronic Postsurgical Pain in Breast Cancer Patients: A Randomized Controlled Trial.

Pain Med 2020 12;21(12):3539-3547

Department of Anaesthesiology and Critical Care Medicine, Peking University First Hospital, Beijing, China.

Objective: To evaluate the effect of multilevel single-shot thoracic paravertebral blockade (PVB) on the occurrence of chronic postsurgical pain (CPSP) in patients undergoing breast cancer surgery.

Design: A randomized controlled trial with two parallel groups.

Setting: A tertiary hospital.

Methods: Patients scheduled for breast cancer surgery were randomized to receive either ultrasound-guided multilevel single-shot PVB from T2 to T5 (the PVB group) or nothing (the control group). Surgery was then performed under general anesthesia. Patients were followed up for 12 months after surgery. The primary end point was incidence of CPSP at six months after surgery.

Results: A total of 218 patients were enrolled and randomized; of these, 208 and 204 completed six- and 12-month follow-up, respectively. The incidence of CPSP at six months was significantly lower in the PVB group (12.5% [13/104]) than in the control group (24.0% [25/104], relative risk = 0.52, 95% CI = 0.28-0.96, P = 0.031). Pain scores within 48 hours both at rest and with movement were lower in the PVB group than the control group (P = 0.006 and P < 0.001, respectively). The percentages of patients with neuropathic pain were also lower in the PVB group than the control group at both six and 12 months after surgery (P = 0.016 and 0.028, respectively). Adverse events did not differ between groups.

Conclusions: For patients undergoing breast cancer surgery, multilevel single-shot PVB reduces the incidence of CPSP at six months; it also improves early postoperative analgesia and reduces neuropathic pain at six and 12 months after surgery.
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http://dx.doi.org/10.1093/pm/pnaa270DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7770235PMC
December 2020

Tuning the Electronic Structure of an α-Antimonene Monolayer through Interface Engineering.

Nano Lett 2020 Nov 16;20(11):8408-8414. Epub 2020 Oct 16.

National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China.

The interfacial charge transfer from the substrate may influence the electronic structure of the epitaxial van der Waals (vdW) monolayers and, thus, their further technological applications. For instance, the freestanding Sb monolayer in the puckered honeycomb phase (α-antimonene), the structural analogue of black phosphorene, was predicted to be a semiconductor, but the epitaxial one behaves as a gapless semimetal when grown on the -WTe substrate. Here, we demonstrate that interface engineering can be applied to tune the interfacial charge transfer and, thus, the electron band of the epitaxial monolayer. As a result, the nearly freestanding (semiconducting) α-antimonene monolayer with a band gap of ∼170 meV was successfully obtained on the SnSe substrate. Furthermore, a semiconductor-semimetal crossover is observed in the bilayer α-antimonene. This study paves the way toward modifying the electron structure in two-dimensional vdW materials through interface engineering.
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http://dx.doi.org/10.1021/acs.nanolett.0c03704DOI Listing
November 2020

Zhu et al. Reply.

Phys Rev Lett 2020 Aug;125(7):079702

National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China.

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http://dx.doi.org/10.1103/PhysRevLett.125.079702DOI Listing
August 2020

Quasiparticle interference evidence of the topological Fermi arc states in chiral fermionic semimetal CoSi.

Sci Adv 2019 Dec 20;5(12):eaaw9485. Epub 2019 Dec 20.

National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China.

Chiral fermions in solid state feature "Fermi arc" states, connecting the surface projections of the bulk chiral nodes. The surface Fermi arc is a signature of nontrivial bulk topology. Unconventional chiral fermions with an extensive Fermi arc traversing the whole Brillouin zone have been theoretically proposed in CoSi. Here, we use scanning tunneling microscopy/spectroscopy to investigate quasiparticle interference at various terminations of a CoSi single crystal. The observed surface states exhibit chiral fermion-originated characteristics. These reside on (001) and (011) but not (111) surfaces with p-rotation symmetry, spiral with energy, and disperse in a wide energy range from ~-200 to ~+400 mV. Owing to the high-energy and high-space resolution, a spin-orbit coupling-induced splitting of up to ~80 mV is identified. Our observations are corroborated by density functional theory and provide strong evidence that CoSi hosts the unconventional chiral fermions and the extensive Fermi arc states.
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http://dx.doi.org/10.1126/sciadv.aaw9485DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6989308PMC
December 2019

Proton-assisted growth of ultra-flat graphene films.

Nature 2020 01 8;577(7789):204-208. Epub 2020 Jan 8.

National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing, China.

Graphene films grown by chemical vapour deposition have unusual physical and chemical properties that offer promise for applications such as flexible electronics and high-frequency transistors. However, wrinkles invariably form during growth because of the strong coupling to the substrate, and these limit the large-scale homogeneity of the film. Here we develop a proton-assisted method of chemical vapour deposition to grow ultra-flat graphene films that are wrinkle-free. Our method of proton penetration and recombination to form hydrogen can also reduce the wrinkles formed during traditional chemical vapour deposition of graphene. Some of the wrinkles disappear entirely, owing to the decoupling of van der Waals interactions and possibly an increase in distance from the growth surface. The electronic band structure of the as-grown graphene films shows a V-shaped Dirac cone and a linear dispersion relation within the atomic plane or across an atomic step, confirming the decoupling from the substrate. The ultra-flat nature of the graphene films ensures that their surfaces are easy to clean after a wet transfer process. A robust quantum Hall effect appears even at room temperature in a device with a linewidth of 100 micrometres. Graphene films grown by proton-assisted chemical vapour deposition should largely retain their intrinsic performance, and our method should be easily generalizable to other nanomaterials for strain and doping engineering.
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http://dx.doi.org/10.1038/s41586-019-1870-3DOI Listing
January 2020

Realization of a Metallic State in 1T-TaS_{2} with Persisting Long-Range Order of a Charge Density Wave.

Phys Rev Lett 2019 Nov;123(20):206405

National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China.

Metallization of 1T-TaS_{2} is generally initiated at the domain boundary of a charge density wave (CDW), at the expense of its long-range order. However, we demonstrate in this study that the metallization of 1T-TaS_{2} can be also realized without breaking the long-range CDW order upon surface alkali doping. By using scanning tunneling microscopy, we find the long-range CDW order is always persisting, and the metallization is instead associated with additional in-gap excitations. Interestingly, the in-gap excitation is near the top of the lower Hubbard band, in contrast to a conventional electron-doped Mott insulator where it is beneath the upper Hubbard band. In combination with the numerical calculations, we suggest that the appearance of the in-gap excitations near the lower Hubbard band is mainly due to the effectively reduced on-site Coulomb energy by the adsorbed alkali ions.
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http://dx.doi.org/10.1103/PhysRevLett.123.206405DOI Listing
November 2019

Decentralized Privacy-Preserving Platform for Clinical Data Sharing and Analysis.

Stud Health Technol Inform 2019 Aug;264:839-842

IBM Research - China, Beijing, China.

Collection and management of clinical data for administration and analysis is a time-consuming and complex task, especially when multiple data providers been involved. Even if people are willing to take on the burden for it, there is still no mature solution to protect data privacy for distributed data providers. Distributed ledger is an emerging technology that supports decentralized data sharing and management. Based on this, we present a platform which enables distributed and truthful data collection and serves privacy-preserving needs in clinical data management. Our system, built on Hyperledger Fabric, used smart contract to execute data aggregation and provide basic analysis methods. The system used ledger and world status to record data access history and other metadata. This decentralized platform enables data providers to proactively share and protect their data, Thus can simplify clinical data collection procedure and promote efficient collaboration between providers.
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http://dx.doi.org/10.3233/SHTI190341DOI Listing
August 2019

Van der Waals Heteroepitaxial Growth of Monolayer Sb in a Puckered Honeycomb Structure.

Adv Mater 2019 Feb 5;31(5):e1806130. Epub 2018 Dec 5.

National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China.

Atomically thin 2D crystals have gained tremendous attention owing to their potential impact on future electronics technologies, as well as the exotic phenomena emerging in these materials. Monolayers of α-phase Sb (α-antimonene), which shares the same puckered structure as black phosphorous, are predicted to be stable with precious properties. However, the experimental realization still remains challenging. Here, high-quality monolayerα-antimonene is successfully grown, with the thickness finely controlled. The α-antimonene exhibits great stability upon exposure to air. Combining scanning tunneling microscopy, density functional theory calculations, and transport measurements, it is found that the electron band crossing the Fermi level exhibits a linear dispersion with a fairly small effective mass, and thus a good electrical conductivity. All of these properties make the α-antimonene promising for future electronic applications.
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http://dx.doi.org/10.1002/adma.201806130DOI Listing
February 2019

Observation of Coulomb gap in the quantum spin Hall candidate single-layer 1T'-WTe.

Nat Commun 2018 10 4;9(1):4071. Epub 2018 Oct 4.

National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, 210093, Nanjing, China.

The two-dimensional topological insulators host a full gap in the bulk band, induced by spin-orbit coupling (SOC) effect, together with the topologically protected gapless edge states. However, it is usually challenging to suppress the bulk conductance and thus to realize the quantum spin Hall (QSH) effect. In this study, we find a mechanism to effectively suppress the bulk conductance. By using the quasiparticle interference technique with scanning tunneling spectroscopy, we demonstrate that the QSH candidate single-layer 1T'-WTe has a semimetal bulk band structure with no full SOC-induced gap. Surprisingly, in this two-dimensional system, we find the electron-electron interactions open a Coulomb gap which is always pinned at the Fermi energy (E). The opening of the Coulomb gap can efficiently diminish the bulk state at the E and supports the observation of the quantized conduction of topological edge states.
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http://dx.doi.org/10.1038/s41467-018-06635-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6172222PMC
October 2018

Superconductivity in Potassium-Intercalated T -WTe.

Nano Lett 2018 10 20;18(10):6585-6590. Epub 2018 Sep 20.

National Laboratory of Solid State Microstructures, School of Physics , Nanjing University , Nanjing 210093 , China.

To realize a topological superconductor is one of the most attracting topics because of its great potential in quantum computation. In this study, we successfully intercalate potassium (K) into the van der Waals gap of type II Weyl semimetal WTe and discover the superconducting state in K WTe through both electrical transport and scanning tunneling spectroscopy measurements. The superconductivity exhibits an evident anisotropic behavior. Moreover, we also uncover the coexistence of superconductivity and the positive magnetoresistance state. Structural analysis substantiates the negligible lattice expansion induced by the intercalation, therefore suggesting K-intercalated WTe still hosts the topological nontrivial state. These results indicate that the K-intercalated WTe may be a promising candidate to explore the topological superconductor.
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http://dx.doi.org/10.1021/acs.nanolett.8b03180DOI Listing
October 2018

High amplification levels of MDM2 and CDK4 correlate with poor outcome in patients with dedifferentiated liposarcoma: A cytogenomic microarray analysis of 47 cases.

Cancer Genet 2017 Dec 22;218-219:69-80. Epub 2017 Sep 22.

Department of Pathology, University of Washington School of Medicine, Seattle, WA. Electronic address:

Dedifferentiated liposarcoma (DDLS) is characterized at the molecular level by amplification of genes within 12q13-15 including MDM2 and CDK4. However, other than FNCLCC grade, prognostic markers are limited. We aim to identify molecular prognostic markers for DDLS to help risk stratify patients. To this end, we studied 49 cases of DDLS in our institutional archives and performed cytogenomic microarray analysis on 47 cases. Gene copy numbers for 12 loci were evaluated and correlated with outcome data retrieved from our institutional electronic medical records. Using cut point analysis and comparison of Kaplan-Meier survival curves by log rank tests, high amplification levels of MDM2 (>38 copies) and CDK4 (>30 copies) correlated with decreased disease free survival (DFS) (P = .0168 and 0.0169 respectively) and disease specific survival (DSS) (P = .0082 and 0.0140 respectively). Additionally, MDM2 and CDK4 showed evidence of a synergistic effect so that each additional copy of one enhances the effect on prognosis of each additional copy of the other for decreased DFS (P = .0227, 0.1% hazard). High amplification of JUN (>16 copies) also correlated with decreased DFS (P = .0217), but not DSS. The presence of copy number alteration at 3q29 correlated with decreased DSS (P = .0192). The presence of >10 mitoses per 10 high power fields and FNCLCC grade 3 also correlated with decreased DFS (P = .0310 and 0.0254 respectively). MDM2 and CDK4 gene amplification levels, along with JUN amplification and copy alterations at 3q29, can be utilized for predicting outcome in patients with DDLS.
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http://dx.doi.org/10.1016/j.cancergen.2017.09.005DOI Listing
December 2017

Identification of Lattice Oxygen in Few-Layer Black Phosphorous Exfoliated in Ultrahigh Vacuum and Largely Improved Ambipolar Field-Effect Mobilities by Hydrogenation and Phosphorization.

ACS Appl Mater Interfaces 2017 Nov 2;9(45):39804-39811. Epub 2017 Nov 2.

Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures and Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Nanjing University , Nanjing 210093, China.

Black phosphorus (BP) has recently attracted considerable attention due to its unique structure and fascinating optical and electronic properties as well as possible applications in photothermal agents. However, its main drawback is rapid degradation in ambient environments of HO and O, which has led to much research on the improvement of its stability. Unfortunately, this research has not shown great improvement in carrier mobilities. Here, we perform scanning tunneling microscopy observations of few-layer BP (FLBP) sheets exfoliated in ultrahigh vacuum and reveal, for the first time, the existence of lattice oxygen introduced during crystal growth. As a proof-of-concept application, hydrogenation is conducted to remove the lattice oxygen atoms followed by phosphorization, which repairs the phosphorous vacancies caused by mechanical exfoliation and hydrogenation. The resulting FLBP sheets show high ambipolar field-effect mobilities of 1374 cm V s for holes and 607 cm V s for electrons at 2 K. After storage in air for 3 days, the hole and electron mobilities only decrease to 1181 and 518 cm V s, respectively, and no structural degradation is observed. This work suggests an effective means to improve both the mobility and stability of BP sheets rendering practical application of FLBP sheets possible.
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http://dx.doi.org/10.1021/acsami.7b12469DOI Listing
November 2017

Supramolecular Motors on Graphite Surface Stabilized by Charge States and Hydrogen Bonds.

ACS Nano 2017 10 19;11(10):10236-10242. Epub 2017 Sep 19.

School of Physical Science and Technology and Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, Southwest University , Chongqing 400715, China.

Molecular motors are nanoscale machines that convert external energies into controlled mechanical movements. In supramolecular motors, the rotator and stator are held together mechanically, and thus the rotation can be essentially barrier free when molecular conformation is negligible. However, nearly all the supramolecular motors appeared in solutions or host-guest complexes. Surface-mounted supramolecular motors have rarely been addressed, even though they are easily manipulated by external fields. Here we report a surface-mounted supramolecular motor assembled by charge states and hydrogen bonds. On a graphite surface, individual ethanol clusters can be charged with a scanning tunneling microscopy tip and then trap the ethanol chains with a permanent dipole moment. Serving as a rotator, the trapped ethanol chains rotate around a charged cluster driven by the inelastic tunneling electrons. Random rotation in clockwise or anticlockwise direction occurs in the chiral molecular chains through chiral flipping. Directional rotation with clockwise chirality can be realized by introducing a chiral branch to the near end of ethanol chains to suppress the chiral flipping with steric hindrance.
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http://dx.doi.org/10.1021/acsnano.7b04811DOI Listing
October 2017

Allicin improves cardiac function by protecting against apoptosis in rat model of myocardial infarction.

Chin J Integr Med 2017 Aug 13;23(8):589-597. Epub 2016 Jul 13.

Laboratory of Academician LI Lian-da, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, 100091, China.

Objective: To study the effects of allicin on cardiac function and underlying mechanism in rat model of myocardial infarction (MI).

Methods: Ninety-four Wistar rats were randomly assigned to 6 groups (n=14-16 per group): sham control group [underwent thoracotomy without left anterior descending (LAD) occlusion and only received an injection of the same amount of citrate buffer], MI control group (subjected to LAD occlusion and only received an injection of same amount of citrate buffer), positive control group (subjected to LAD occlusion and received an injection of diltiazem hydrochloride at the dose of 1.5 mg/kg), and MI + allicin groups (subjected to LAD occlusion and received an injection of allicin at the doses of 1.2, 1.8, and 3.6 mg/kg). All of the drugs were administered intraperitoneally daily for 21 days. The infarct area was measured by myocardial staining. Hematoxylin-eosin staining was used to observe the pathological changes. Cardiac function parameters were assessed by echocardiography. The myocardial apoptotic index was estimated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining. The expression of Bax and Bcl-2 were detected by quantificational real-time polymerase chain reaction and Western blot.

Results: Treatment with allicin could attenuate the myocardial infarct area (P<0.05) and relieve the changes of the myocardium. The left ventricular anterior wall diastolic and systolic thicknesses were increased in the allicin-treated groups (P<0.05), while there was no signifificant difference in the left ventricular posterior wall diastolic and systolic thickness (P>0.05). The left ventricular internal diameter in systole, ejection fraction, fractional shortening, and stroke volume were dramatically elevated in allicin-treated rats (P<0.05). Allicin dose-dependently reduced creatine kinase and lactate dehydrogenase levels (P<0.05). The myocardial apoptotic index was also markedly lowered, and Bax expression was signifificantly decreased, whereas Bcl-2 expression exhibited an opposite trend in allicin-treated rats (P<0.05).

Conclusion: Allicin appears to exert a cardioprotective effect that may be linked to blocking Bcl-2/Bax signaling pathway-denpendent apoptosis, further improving cardiac function.
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http://dx.doi.org/10.1007/s11655-016-2523-0DOI Listing
August 2017

Majorana Zero Mode Detected with Spin Selective Andreev Reflection in the Vortex of a Topological Superconductor.

Phys Rev Lett 2016 Jun 21;116(25):257003. Epub 2016 Jun 21.

Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.

Recently, theory has predicted a Majorana zero mode (MZM) to induce spin selective Andreev reflection (SSAR), a novel magnetic property which can be used to detect the MZM. Here, spin-polarized scanning tunneling microscopy or spectroscopy has been applied to probe SSAR of MZMs in a topological superconductor of the Bi_{2}Te_{3}/NbSe_{2} heterostructure. The zero-bias peak of the tunneling differential conductance at the vortex center is observed substantially higher when the tip polarization and the external magnetic field are parallel rather than antiparallel to each other. This spin dependent tunneling effect provides direct evidence of MZM and reveals its magnetic property in addition to the zero energy modes. Our work will stimulate MZM research on these novel physical properties and, hence, is a step towards experimental study of their statistics and application in quantum computing.
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http://dx.doi.org/10.1103/PhysRevLett.116.257003DOI Listing
June 2016

[Effect of allicin on myocardial fibrosis after myocardial infarction in rats and its relationship with TGFβ/Smads signal transduction].

Zhongguo Zhong Yao Za Zhi 2016 Jul;41(13):2517-2521

Li Lianda Academician Research Laboratory, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, China.

Allicin is the internationally accepted active substance of garlic, and has cardiovascular protective effect. This research was designed to investigate the effect of allicin on myocardial fibrosis after myocardial infarction and explore the relationship between the effect and TGFβ1/Smads signaling pathway. The rat myocardial infarction model were made by ligating the left anterior desending coronary artery. The drugs were administered intraperitoneally 24 h after the operation. After 21 days, the rats were sacrificed and myocardial collagen fibres were observed by Masson staining. The protein expression of Ⅰ, Ⅲ collagen and TGFβ1, Smad3, Smad7 in the myocardium was measured by the immunohistochemistry. The results showed that myocardial fibrosis was serious and the expression of Ⅰ, Ⅲ collagen was increased in model group. After treatment with allicin, the myocardial fibrosis could be relieved markedly, and the expression of collagen was down-regulated. Meanwhile, TGFβ1 and Smad3 in heart tissue could be down-regulated and Smad7 could be up-regulated in allicin groups. So allicin may exhibit anti-myocardial fibrosis effect on rats, and the mechanism of this is related to TGFβ/Smads signal transduction.
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http://dx.doi.org/10.4268/cjcmm20161324DOI Listing
July 2016

Tailoring Kinetics on a Topological Insulator Surface by Defect-Induced Strain: Pb Mobility on Bi2Te3.

Nano Lett 2016 07 20;16(7):4454-61. Epub 2016 Jun 20.

Department of Physics and Astronomy, Iowa State University , Ames, Iowa 50011, United States.

Heteroepitaxial structures based on Bi2Te3-type topological insulators (TIs) exhibit exotic quantum phenomena. For optimal characterization of these phenomena, it is desirable to control the interface structure during film growth on such TIs. In this process, adatom mobility is a key factor. We demonstrate that Pb mobility on the Bi2Te3(111) surface can be modified by the engineering local strain, ε, which is induced around the point-like defects intrinsically forming in the Bi2Te3(111) thin film grown on a Si(111)-7 × 7 substrate. Scanning tunneling microscopy observations of Pb adatom and cluster distributions and first-principles density functional theory (DFT) analyses of the adsorption energy and diffusion barrier Ed of Pb adatom on Bi2Te3(111) surface show a significant influence of ε. Surprisingly, Ed reveals a cusp-like dependence on ε due to a bifurcation in the position of the stable adsorption site at the critical tensile strain εc ≈ 0.8%. This constitutes a very different strain-dependence of diffusivity from all previous studies focusing on conventional metal or semiconductor surfaces. Kinetic Monte Carlo simulations of Pb deposition, diffusion, and irreversible aggregation incorporating the DFT results reveal adatom and cluster distributions compatible with our experimental observations.
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http://dx.doi.org/10.1021/acs.nanolett.6b01604DOI Listing
July 2016

Experimental Observation of Topological Edge States at the Surface Step Edge of the Topological Insulator ZrTe_{5}.

Phys Rev Lett 2016 Apr 28;116(17):176803. Epub 2016 Apr 28.

National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, Jiangsu 210093, China.

We report an atomic-scale characterization of ZrTe_{5} by using scanning tunneling microscopy. We observe a bulk band gap of ∼80  meV with topological edge states at the step edge and, thus, demonstrate that ZrTe_{5} is a two-dimensional topological insulator. We also find that an applied magnetic field induces an energetic splitting of the topological edge states, which can be attributed to a strong link between the topological edge states and bulk topology. The relatively large band gap makes ZrTe_{5} a potential candidate for future fundamental studies and device applications.
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http://dx.doi.org/10.1103/PhysRevLett.116.176803DOI Listing
April 2016

Influence of strain on water adsorption and dissociation on rutile TiO2(110) surface.

Phys Chem Chem Phys 2016 06;18(22):14833-9

National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China.

The influence of externally applied strain on water adsorption and dissociation on a defect-free rutile TiO2(110) surface is studied by using first-principles calculations. We found that while compressive strain makes water adsorption and dissociation less favorable, tensile strain increases the energy gain of water adsorption, and decreases the energy cost of water dissociation. Specifically, dissociative water becomes more stable than molecular water when an 8% tensile in-plane strain is applied. Moreover, the dissociation barrier decreases with increasing strain more rapidly for more isolated water. The rate of decrease of this barrier for nearly isolated water is 0.017 eV per 1% biaxial strain. This demonstrates that applying strain is a possible way to engineer the surface adsorption and dissociation of water on a TiO2(110) surface, and therefore engineer the relevant surface reactivity.
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http://dx.doi.org/10.1039/c6cp01106cDOI Listing
June 2016

[Exercise echocardiography in the evaluation of obstructive types of hypertrophic cardiomyopathy].

Zhonghua Nei Ke Za Zhi 2013 Jun;52(6):484-8

Chinese Academy of Medical Science of Medical Sciences and Peking Union Medical College, Fuwai Hospital, Beijing 100037, China.

Objective: To assess the condition of left ventricular outflow tract obstruction (LVOTO) under resting conditions and physiological exercise in hypertrophic cardiomyopathy (HCM) patients.

Methods: A total of 60 patients with HCM and left ventricular outflow tract gradient (LVOTG) <50 mm Hg (1 mm Hg = 0.133 kPa) at rest were enrolled consecutively, and LVOTG at rest and exercise were measured by echocardiography. Of 51 patients with gradients <30 mm Hg at rest, 26 were latent LVOTO with exercise peak value LVOTG ≥ 30 mm Hg, 25 were non LVOTO with exercise peak value LVOTG < 30 mm Hg, and 9 were resting obstruction with LVOTG 30-49 mm Hg. The morphological characteristics of different types of obstruction were analyzed.

Results: Patients with latent LVOTO were more likely to have SAM (73.1% vs 8.0%) , narrow of LVOT (46.2% vs 4.0%) , higher resting gradients [(16.9 ± 7.2) mm Hg vs (7.1 ± 4.3) mm Hg] and mitral regurgitation grade at rest than patients with non-obstructive (all P values <0.05). The distribution of septal hypertrophy were different in the two groups (P < 0.05). Multivariate logistic regression analysis showed independent predictors of latent LVOTO were SAM (OR 6.431, 95%CI 2.323-291.112, P = 0.002) at rest and distribution of septal hypertrophy(OR 0.011, 95% CI 0.001-0.179, P = 0.008).

Conclusions: Approximately half of patients with non-obstructive HCM at rest have latent LVOTO. SAM and distribution of septal hypertrophy may be useful to identify patients with latent obstruction.
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June 2013
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