Topological electronic structure and spin texture of quasi-one-dimensional higher-order topological insulator Bi4Br4.

The notion of topological insulators (TIs), characterized by an insulating bulk and conducting topological surface states, can be extended to higher-order topological insulators (HOTIs) hosting gapless modes localized at the boundaries of two or more dimensions lower than the insulating bulk. In this work, by performing high-resolution angle-resolved photoemission spectroscopy (ARPES) measurements with submicron spatial and spin resolution, we systematically investigate the electronic structure and spin texture of quasi-one-dimensional (1D) HOTI candidate Bi4Br4. In contrast to the bulk-state-dominant spectra on the (001) surface, we observe gapped surface states on the (100) surface, whose dispersion and spin-polarization agree well with our ab-initio calculations. Moreover, we reveal in-gap states connecting the surface valence and conduction bands, which is a signature of the hinge states inside the (100) surface gap. Our findings provide compelling evidence for the HOTI phase of Bi4Br4. The identification of the higher-order topological phase promises applications based on 1D spin-momentum locked current in electronic and spintronic devices.

Twist-Induced Modification in the Electronic Structure of Bilayer WSe2.

The recent discovery of strongly correlated phases in twisted transition-metal dichalcogenides (TMDs) highlights the significant impact of twist-induced modifications on electronic structures. In this study, we employed angle-resolved photoemission spectroscopy with submicrometer spatial resolution (µ-ARPES) to investigate these modifications by comparing valence band structures of twisted (5.3°) and nontwisted (AB-stacked) bilayer regions within the same WSe2 device. Relative to the nontwisted region, the twisted area exhibits pronounced moiré bands and ∼90 meV renormalization at the Γ-valley, substantial momentum separation between different layers, and an absence of flat bands at the K-valley. We further simulated the effects of lattice relaxation, which can flatten the Γ-valley edge but not the K-valley edge. Our results provide a direct visualization of twist-induced modifications in the electronic structures of twisted TMDs and elucidate their valley-dependent responses to lattice relaxation.

Topology Hierarchy of Transition Metal Dichalcogenides Built from Quantum Spin Hall Layers.

The evolution of the physical properties of 2D material from monolayer limit to the bulk reveals unique consequences from dimension confinement and provides a distinct tuning knob for applications. Monolayer 1T'-phase transition metal dichalcogenides (1T'-TMDs) with ubiquitous quantum spin Hall (QSH) states are ideal 2D building blocks of various 3D topological phases. However, the stacking geometry has been previously limited to the bulk 1T'-WTe2 type. Here, the novel 2M-TMDs consisting of translationally stacked 1T'-monolayers are introduced as promising material platforms with tunable inverted bandgaps and interlayer coupling. By performing advanced polarization-dependent angle-resolved photoemission spectroscopy as well as first-principles calculations on the electronic structure of 2M-TMDs, a topology hierarchy is revealed: 2M-WSe2 , MoS2, and MoSe2 are weak topological insulators (WTIs), whereas 2M-WS2 is a strong topological insulator (STI). Further demonstration of topological phase transitions by tunning interlayer distance indicates that band inversion amplitude and interlayer coupling jointly determine different topological states in 2M-TMDs. It is proposed that 2M-TMDs are parent compounds of various exotic phases including topological superconductors and promise great application potentials in quantum electronics due to their flexibility in patterning with 2D materials.

Observation of Coexisting Dirac Bands and Moiré Flat Bands in Magic-Angle Twisted Trilayer Graphene.

Moiré superlattices that consist of two or more layers of 2D materials stacked together with a small twist angle have emerged as a tunable platform to realize various correlated and topological phases, such as Mott insulators, unconventional superconductivity, and quantum anomalous Hall effect. Recently, magic-angle twisted trilayer graphene (MATTG) has shown both robust superconductivity similar to magic-angle twisted bilayer graphene and other unique properties, including the Pauli-limit violating and re-entrant superconductivity. These rich properties are deeply rooted in its electronic structure under the influence of distinct moiré potential and mirror symmetry. Here, combining nanometer-scale spatially resolved angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy, the as-yet unexplored band structure of MATTG near charge neutrality is systematically measured. These measurements reveal the coexistence of the distinct dispersive Dirac band with the emergent moiré flat band, showing nice agreement with the theoretical calculations. These results serve as a stepstone for further understanding of the unconventional superconductivity in MATTG.

Development and research of compound caffeine waterless swallowed granules based on reverse engineering / 药学学报

In this study, the reverse engineering technology was used to analyze the prescription and process of Doppelherz® Energy DIRECT, based on the composition of the prescription on the official website of the product, the detection method of composition is established according to the pharmacopoeia and literature information, combined with gravimetric analysis to complete prescription analysis. The prescription composition of the reference listed drug was determined to be composed of caffeine, taurine, vitamin B, anhydrous glucose, citric acid, sorbitol, sucralose, magnesium salts of fatty acids, in which the glucose content was 71.4%, the citric acid content was 7.0% and the magnesium salts of fatty acids content was < 5.8%. According to patent inquiry, Raman imaging and other technologies, the preparation process of the marketed preparation has been basically obtained, and the development of the self-made preparation has been completed on this basis. The study was approved by the Ethics Committee of the Academy of Military Medical Sciences. Combined with the results of the taste evaluation experiment and the caffeine dissolution test of the preparation in 1 min, the hot-melt extrusion technology was screened out as the taste-masking technology of the self-made preparation, the parameters of the hot-melt extrusion process were screened by differential scanning calorimetry analysis, and finally a product with good taste and qualified quality was obtained, which provided a reference method for the research and development of related preparations.

Hetero-site nucleation for growing twisted bilayer graphene with a wide range of twist angles.

Twisted bilayer graphene (tBLG) has recently attracted growing interest due to its unique twist-angle-dependent electronic properties. The preparation of high-quality large-area bilayer graphene with rich rotation angles would be important for the investigation of angle-dependent physics and applications, which, however, is still challenging. Here, we demonstrate a chemical vapor deposition (CVD) approach for growing high-quality tBLG using a hetero-site nucleation strategy, which enables the nucleation of the second layer at a different site from that of the first layer. The fraction of tBLGs in bilayer graphene domains with twist angles ranging from 0° to 30° was found to be improved to 88%, which is significantly higher than those reported previously. The hetero-site nucleation behavior was carefully investigated using an isotope-labeling technique. Furthermore, the clear Moiré patterns and ultrahigh room-temperature carrier mobility of 68,000 cm2 V-1 s-1 confirmed the high crystalline quality of our tBLG. Our study opens an avenue for the controllable growth of tBLGs for both fundamental research and practical applications.

Weyl fermions, Fermi arcs, and minority-spin carriers in ferromagnetic CoS2.

Magnetic Weyl semimetals are a newly discovered class of topological materials that may serve as a platform for exotic phenomena, such as axion insulators or the quantum anomalous Hall effect. Here, we use angle-resolved photoelectron spectroscopy and ab initio calculations to discover Weyl cones in CoS2, a ferromagnet with pyrite structure that has been long studied as a candidate for half-metallicity, which makes it an attractive material for spintronic devices. We directly observe the topological Fermi arc surface states that link the Weyl nodes, which will influence the performance of CoS2 as a spin injector by modifying its spin polarization at interfaces. In addition, we directly observe a minority-spin bulk electron pocket in the corner of the Brillouin zone, which proves that CoS2 cannot be a true half-metal.

Interaction effects and superconductivity signatures in twisted double-bilayer WSe2.

Twisted bilayer graphene provides a new two-dimensional platform for studying electron interaction phenomena and flat band properties such as correlated insulator transition, superconductivity and ferromagnetism at certain magic angles. Here, we present experimental characterization of interaction effects and superconductivity signatures in p-type twisted double-bilayer WSe2. Enhanced interlayer interactions are observed when the twist angle decreases to a few degrees as reflected by the high-order satellites in the electron diffraction patterns taken from the reconstructed domains from a conventional moiré superlattice. In contrast to twisted bilayer graphene, there is no specific magic angle for twisted WSe2. Flat band properties are observable at twist angles ranging from 1 to 4 degrees. Our work has facilitated future study in the area of flat band related properties in twisted transition metal dichalcogenide layered structures.

Handedness-dependent quasiparticle interference in the two enantiomers of the topological chiral semimetal PdGa.

It has recently been proposed that combining chirality with topological band theory results in a totally new class of fermions. Understanding how these unconventional quasiparticles propagate and interact remains largely unexplored so far. Here, we use scanning tunneling microscopy to visualize the electronic properties of the prototypical chiral topological semimetal PdGa. We reveal chiral quantum interference patterns of opposite spiraling directions for the two PdGa enantiomers, a direct manifestation of the change of sign of their Chern number. Additionally, we demonstrate that PdGa remains topologically non-trivial over a large energy range, experimentally detecting Fermi arcs in an energy window of more than 1.6 eV that is symmetrically centered around the Fermi level. These results are a consequence of the deep connection between chirality in real and reciprocal space in this class of materials, and, thereby, establish PdGa as an ideal topological chiral semimetal.

Observation and control of maximal Chern numbers in a chiral topological semimetal.

Topological semimetals feature protected nodal band degeneracies characterized by a topological invariant known as the Chern number (C). Nodal band crossings with linear dispersion are expected to have at most [Formula: see text], which sets an upper limit to the magnitude of many topological phenomena in these materials. Here, we show that the chiral crystal palladium gallium (PdGa) displays multifold band crossings, which are connected by exactly four surface Fermi arcs, thus proving that they carry the maximal Chern number magnitude of 4. By comparing two enantiomers, we observe a reversal of their Fermi-arc velocities, which demonstrates that the handedness of chiral crystals can be used to control the sign of their Chern numbers.

Super resolution convolutional neural network for feature extraction in spectroscopic data.

Two dimensional (2D) peak finding is a common practice in data analysis for physics experiments, which is typically achieved by computing the local derivatives. However, this method is inherently unstable when the local landscape is complicated or the signal-to-noise ratio of the data is low. In this work, we propose a new method in which the peak tracking task is formalized as an inverse problem, which thus can be solved with a convolutional neural network (CNN). In addition, we show that the underlying physics principle of the experiments can be used to generate the training data. By generalizing the trained neural network on real experimental data, we show that the CNN method can achieve comparable or better results than traditional derivative based methods. This approach can be further generalized in different physics experiments when the physical process is known.

Persistent surface states with diminishing gap in MnBi2Te4/Bi2Te3 superlattice antiferromagnetic topological insulator.

Magnetic topological quantum materials (TQMs) provide a fertile ground for the emergence of fascinating topological magneto-electric effects. Recently, the discovery of intrinsic antiferromagnetic (AFM) topological insulator MnBi2Te4 that could realize quantized anomalous Hall effect and axion insulator phase ignited intensive study on this family of TQM compounds. Here, we investigated the AFM compound MnBi4Te7 where Bi2Te3 and MnBi2Te4 layers alternate to form a superlattice. Using spatial- and angle-resolved photoemission spectroscopy, we identified ubiquitous (albeit termination dependent) topological electronic structures from both Bi2Te3 and MnBi2Te4 terminations. Unexpectedly, while the bulk bands show strong temperature dependence correlated with the AFM transition, the topological surface states with a diminishing gap show negligible temperature dependence across the AFM transition. Together with the results of its sister compound MnBi2Te4, we illustrate important aspects of electronic structures and the effect of magnetic ordering in this family of magnetic TQMs.

Electronic origin of the enhanced thermoelectric efficiency of Cu2Se.

Thermoelectric materials (TMs) can uniquely convert waste heat into electricity, which provides a potential solution for the global energy crisis that is increasingly severe. Bulk Cu2Se, with ionic conductivity of Cu ions, exhibits a significant enhancement of its thermoelectric figure of merit zT by a factor of ~3 near its structural transition around 400 K. Here, we show a systematic study of the electronic structure of Cu2Se and its temperature evolution using high-resolution angle-resolved photoemission spectroscopy. Upon heating across the structural transition, the electronic states near the corner of the Brillouin zone gradually disappear, while the bands near the centre of Brillouin zone shift abruptly towards high binding energies and develop an energy gap. Interestingly, the observed band reconstruction well reproduces the temperature evolution of the Seebeck coefficient of Cu2Se, providing an electronic origin for the drastic enhancement of the thermoelectric performance near 400 K. The current results not only bridge among structural phase transition, electronic structures and thermoelectric properties in a condensed matter system, but also provide valuable insights into the search and design of new generation of thermoelectric materials.

Electronic structures and unusually robust bandgap in an ultrahigh-mobility layered oxide semiconductor, Bi2O2Se.

Semiconductors are essential materials that affect our everyday life in the modern world. Two-dimensional semiconductors with high mobility and moderate bandgap are particularly attractive today because of their potential application in fast, low-power, and ultrasmall/thin electronic devices. We investigate the electronic structures of a new layered air-stable oxide semiconductor, Bi2O2Se, with ultrahigh mobility (~2.8 × 105 cm2/V⋅s at 2.0 K) and moderate bandgap (~0.8 eV). Combining angle-resolved photoemission spectroscopy and scanning tunneling microscopy, we mapped out the complete band structures of Bi2O2Se with key parameters (for example, effective mass, Fermi velocity, and bandgap). The unusual spatial uniformity of the bandgap without undesired in-gap states on the sample surface with up to ~50% defects makes Bi2O2Se an ideal semiconductor for future electronic applications. In addition, the structural compatibility between Bi2O2Se and interesting perovskite oxides (for example, cuprate high-transition temperature superconductors and commonly used substrate material SrTiO3) further makes heterostructures between Bi2O2Se and these oxides possible platforms for realizing novel physical phenomena, such as topological superconductivity, Josephson junction field-effect transistor, new superconducting optoelectronics, and novel lasers.

A new cytotoxic triterpenoid from microtropis triflora merr. et freem / 中国药学杂志

To study the chemical constituents of Microtropis triflora Merr. et Freem. METHODS: The compounds were isolated and purified by various chromatographic technigues such as silica gel, Sephadex LH -20, and pre-HPLC. Their structures were identified on the basis of chemical properties and spectral analysis. RESULTS: Ten triterpenes were isolated and elucidated as 3, 25-epoxy-lα, 3α, 11α 12, 23, 25-hexahydroxy-urs-12-en(l), β-amyrin(2), β-amyrin palmitate(3), 3β-hydroxy-l1-oxo-olean-12-enyl-3-palmitate(4), lupeol(5), friedelin (6), 3-oxo-28-friedelanoic acid(7), oleanolic acid(8), salaspermic acid (9), and orthosphenic acid(10). CONCLUSION: Compound 1 is a new compound and has cytotoxic activity against Bcap37 and SMMC7721 cells with IC50 values of 27.86 and 11.38 μg· mL-1, respectively.

The diagnostic value of medial temporal volume change in Alzheimer's disease / 中华行为医学与脑科学杂志

ObjectiveTo study the metastructure volumes of medial temporal lobe in diagnosis the patients with Alzheimer's disease (AD) using 3 dimensional MRI.Methods23 AD patients according to DSM-Ⅳ criteria and 23 normal controls (NC) were examined with 3D-MRI.Hippocampus formation,amygdala,entorhinal cortex ( EC ),perirhinal cortex ( PC),and comu temporale were measured with 3D-MRI.ResultsSensitivity and specificity of diagnosis AD were 73.9％,97％ ( Hippocampus formation) ;39.1％,95.7％ (amygdala) ;73.9％,95.7％ (EC) ;95.7％,87.0％ (PC) and 34.8％,39.1％ ( cornu temporale).Overall discriminate function =cornu temporal × 3.887 + PC × 5.960 - EC × 0.074 + amygdale × 3.489 + hippocampus formation × 6.656- 22.449.Over-all-accuracy was 91.3％.ConclusionThe total volume of PC can better diagnosis the mild to moderate AD than other structure of medial temporal lobe.The changes of the medial temporal lobe volume could be used in diagnosis the patients with Alzheimer's disease.

Prevalence and risk factors of asymptomatic intracranial vascular stenosis in patients with essential hypertension / 中华心血管病杂志

<p><b>OBJECTIVE</b>The aim of the study was to determine the prevalence and the distribution pattern of lesion site of intracranial vascular stenosis and to identify risk factors for the stenosis in patients with essential hypertension.</p><p><b>METHODS</b>A total of 231 consecutive inpatients with essential hypertension were included in this study. Patients with the history of cerebrovascular diseases and relevant neurological symptoms were excluded. Intracranial vascular stenosis (>50% diameter reduction) was detected using CT angiography (CTA).</p><p><b>RESULTS</b>Of 231 patients, 69 (29.87%) had intracranial artery stenosis. The most common stenosis site is middle cerebral artery (43.69%), followed by carotid siphon (20.39%). The stenosis in internal carotid arterial system (78.64%) was more common than in vertebrobasilar arterial system (21.56%, P < 0.05). The patients with intracranial vascular stenosis were older, had longer history of hypertension, higher levels of systolic blood pressure, higher plasma cholesterol, higher LDL-C. Lp (a), higher urinary microalbumin excretion, thicker ventricular septum, and lower levels of HDL-C than the patients without stenosis. Logistic analysis showed that systolic blood pressure (OR 1.650, 95% CI 1.134 - 2.400, P = 0.023), course of hypertension (OR 1.238, 95% CI 1.072 - 1.429, P = 0.006), LDL-C (OR 2.103, 95% CI 1.157 - 3.823, P = 0.014) and type 2 diabetes (OR 2.325, 95% CI 1.161 - 4.341, P = 0.011) were the independent risk factors of asymptomatic intracranial arterial stenosis.</p><p><b>CONCLUSIONS</b>Nearly 30% inpatients with essential hypertension had asymptomatic intracranial artery stenosis. The most common site of stenosis was middle cerebral artery. Hypertension, dyslipidemia and diabetes were risk factors for the development of intracranial arterial stenosis.</p>

The preliminary efficacy of interferon-alpha and ribavirin combination treatment of chronic hepatitis C in HIV-infected patients / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>It is internationally accepted that in drug-naïve individuals with hepatitis C virus (HCV) and human immunodeficiency virus (HIV) co-infection, chronic hepatitis C should be treated first if the CD4 cell count does not require the initiation of anti-retroviral therapy. Present paper evaluated the clinical effect and side-effect of interferon-alpha (IFN-alpha) and ribavirin (RBV) combination therapy for Chinese patients with HCV-HIV co-infection, and compared with them for HIV infection alone.</p><p><b>METHODS</b>Ten patients with HCV-HIV and 17 patients with HCV received 5 million unit IFNalpha-2b every other day intramuscularly, and 300 mg RBV triple daily by oral. Dynamic observations were made for HCV RNA and HIV RNA loads, CD4+ and CD8+ T lymphocyte counts, liver function and blood cell measurement, and the medicine side-effects.</p><p><b>RESULTS</b>After 12-week and 24-week treatments of IFN-alpha and RBV combination therapy, mean HCV RNA levels reduced 1.14 logs and 1.56 logs from the baseline at week 0 in HCV-HIV co-infection, and reduced 1.48 logs and 1.75 logs in HCV infection, respectively. The HIV RNA levels decreased 1.22 logs and 1.32 logs from the base line; however, there were no obvious different changes at T lymphocyte counts of HCV-HIV and HCV patients through 24-week treatments. Whole 27 patients showed satisfactory biochemical response to therapy. There were some mild or mediate influence-like symptoms, intestinal uncomfortable and depressed blood cell counts in early stage of the treatments. No neuropsychiatric and auto-immune disorders were found.</p><p><b>CONCLUSIONS</b>IFN-alpha and RBV combination therapy had similar anti-HCV effects during 24-week treatment for HCV-HIV and HCV infected Chinese patients, and some anti-HIV effect. There were no obvious different biochemical responses and side-effects between two groups above.</p>

Interferon-alpha and ribavirin combination therapy for co-infection of hepatitis C virus and human immunodeficiency virus / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To evaluate the clinical effect and side-effect of interferon-alpha (IFN-a) and ribavirin (RBV) combination therapy for Chinese patients with co-infection of hepatitis C virus (HCV) and human immunodeficiency virus (HIV), and to compare them with only HIV infection patients.</p><p><b>METHODS</b>10 patients with HCV-HIV and 17 patients with only HCV infection received 5 million units of IFNalpha-2b every other day intramuscularly, and 300 mg RBV orally three times a day. Dynamic observations were done for HCV RNA and HIV RNA loads, CD4+ and CD8+ T lymphocyte counts, liver function and blood cell measures, and the side-effects of the medicines.</p><p><b>RESULTS</b>After 12 weeks and 24 weeks of IFNalpha and RBV combination therapy, mean HCV RNA levels reduced 1.14 log (t = 3.843, P < 0.01) and 2.08 log (t =6.564, P < 0.01) from the baseline at week 0 in the HCV-HIV co-infection group, and reduced 1.48 log (t = 6.438, P less than 0.01) and 2.33 log (t = 7.343, P < 0.01) in the HCV infection group. Meanwhile, the HIV RNA levels decreased 1.22 log (t = 3.662, P < 0.01) and 1.73 log (t = 6.119, P < 0.01) from the base line. However, there were no obvious different changes among T lymphocyte counts of HCV-HIV and HCV patients at week 0, week 12 and week 24. All 27 patients showed satisfactory biochemical response to therapy. There were some mild or moderate influenza-like symptoms, intestinal discomfort and decreased blood cell counts in the early stages of the treatments. No neuropsychic and auto-immune disorders were found.</p><p><b>CONCLUSIONS</b>IFNalpha-2b and RBV combination therapy showed similar anti-HCV effects during the 24 week treatment for HCV-HIV and HCV infected patients, and some anti-HIV effect was also observed. No obvious different biochemical responses and side-effects were found between the above two groups.</p>

The monitor report of Kashin-Beck Disease prevalence ra te in Changdu of Tibet / 中国地方病学杂志

Objective　To monitor KBD prevalence rate in Changdu of Tibet.Methods　The aged 7～12 year children are tested with X- ray and epidemiological investigation.Results　Xizang are still high yet,the 3 of 4 porints X-rates are more than 20% and the highest one is 55.34%.Conclusions　The Changdu is the severest point of KBD in our country.