ARPES investigation of the electronic structure and its evolution in magnetic topological insulator MnBi2+2nTe4+3n family.

In the past 5 years, there has been significant research interest in the intrinsic magnetic topological insulator family compounds MnBi2+2nTe4+3n (where n = 0, 1, 2 …). In particular, exfoliated thin films of MnBi2Te4 have led to numerous experimental breakthroughs, such as the quantum anomalous Hall effect, axion insulator phase and high-Chern number quantum Hall effect without Landau levels. However, despite extensive efforts, the energy gap of the topological surface states due to exchange magnetic coupling, which is a key feature of the characteristic band structure of the system, remains experimentally elusive. The electronic structure measured by using angle-resolved photoemission (ARPES) shows significant deviation from ab initio prediction and scanning tunneling spectroscopy measurements, making it challenging to understand the transport results based on the electronic structure. This paper reviews the measurements of the band structure of MnBi2+2nTe4+3n magnetic topological insulators using ARPES, focusing on the evolution of their electronic structures with temperature, surface and bulk doping and film thickness. The aim of the review is to construct a unified picture of the electronic structure of MnBi2+2nTe4+3n compounds and explore possible control of their topological properties.

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.

Observation of Mott instability at the valence transition of f-electron system.

Mott physics plays a critical role in materials with strong electronic correlations. Mott insulator-to-metal transition can be driven by chemical doping, external pressure, temperature and gate voltage, which is often seen in transition metal oxides with 3d electrons near the Fermi energy (e.g. cuprate superconductor). In 4f-electron systems, however, the insulator-to-metal transition is mostly driven by Kondo hybridization and the Mott physics has rarely been explored in experiments. Here, by combining the angle-resolved photoemission spectroscopy and strongly correlated band structure calculations, we show that an unusual Mott instability exists in YbInCu4 accompanying its mysterious first-order valence transition. This contrasts with the prevalent Kondo picture and demonstrates that YbInCu4 is a unique platform to explore the Mott physics in Kondo lattice systems. Our work provides important insight for the understanding and manipulation of correlated quantum phenomena in the f-electron system.

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.

Effectiveness of clinical pharmacist-led smartphone application on medication adherence, insulin injection technique and glycemic control for women with gestational diabetes receiving multiple daily insulin injection: A randomized clinical trial.

AIM: To investigate the efficacy of a clinical pharmacist-led smartphone application (app) on medication adherence, insulin injection technique (IIT) and diabetes-related outcomes among women with gestational diabetes mellitus (GDM) receiving insulin therapy. METHOD: In all, 124 women were randomly (1:1 ratio) assigned to receive app intervention plus usual care (intervention) or usual care (control), and were followed up till 12 weeks postpartum. Interventions centralized on medication adherence and IIT. Primary outcome was medication adherence assessed by the 5-item Medication Adherence Report Scale. Secondary outcomes included IIT, insulin requirement, prepartal and puerperal glycemic control, hypoglycemia, and pregnancy and neonatal outcomes. RESULTS: A total of 119 patients completed the follow-up evaluation (58 intervention, 61 control). Significant more women with high medication adherence in the intervention group was observed (69.0% vs. 34.4%, p = 0.000). The other notable benefits (all p < 0.05) included patient percentage with appropriate IIT, lesser preprandial insulin dose, patient proportion with both qualified prepartal FPG and 2 hPG, and puerperal FPG or HbA1c, fewer hypoglycemia, and lower neonatal intensive care unit (NICU) admission rate. Cesarean delivery rate was higher among intervention cases (p < 0.05). Qualified prepartal glycemic control was related to high medication adherence and proper IIT. NICU admission was associated with complicated with gestational hypertension, deficient medication adherence and premature rupture of fetal membrane. CONCLUSION: Combined with usual care, clinical pharmacist-led smartphone app might be a valid tool for GDM management.

Nasal Pressure Injuries Due to Nasal Continuous Positive Airway Pressure Treatment in Newborns: A Prospective Observational Study.

PURPOSE: The purpose of this study was to calculate incidence, severity, and risk factors of nasal pressure injuries due to nasal continuous positive airway pressure (NCPAP) treatment in newborns. DESIGN: A prospective observational study. SUBJECTS AND SETTING: Newborns admitted between March 2017 and February 2018 to the neonatal intensive care unit of the First Affiliated Hospital of Xiamen University, Xiamen, China. METHODS: All newborns' noses were examined during NCPAP application. Every NCPAP-related nasal pressure injury including occurrence date, injury severity, outcomes, and pressure injury treatment methods was recorded. These data were collected twice a week by a research nurse. Nasal pressure injuries were classified using the National Pressure Ulcer Advisory Panel/European Pressure Ulcer Advisory Panel pressure injury classification system. RESULTS: During the study period, 429 newborns received NCPAP treatment via nasal prongs. Nasal pressure injuries were observed in 149 (34.7%); 99 (66.44%) were classified as Stage 1, 48 (32.31%) were Stage 2, and 2 (1.25%) cases were classified as deep tissue injury. The risk of nasal pressure injury was significantly higher when gestational age was less than 32 weeks (odds ratio [OR], 3.728; 95% confidence interval [CI], 1.18-11.77; P ≤ .025) and in those who received NCPAP treatment for more than 6 days (OR, 0.262; 95% CI, 0.087-0.787; P ≤ .017). The mean interval between the application of NCPAP and onset of nasal pressure injury was 4.72 days (SD, 4.78; range, 0-30 days). CONCLUSIONS: Nasal pressure injuries are a prevalent complication of NCPAP use, especially in preterm newborns. Our results identified a gestational age of less than 32 weeks and longer use of NCPAP are important factors associated with nasal pressure injuries. Methods to prevent the development of injuries such as the use of a prophylactic dressing along and replacement of binasal prongs with nasal masks are advocated.

Epitaxial growth and characterization of high quality Bi2O2Se thin films on SrTiO3 substrates by pulsed laser deposition.

Recently, Bi2O2Se was revealed as a promising two-dimensional (2D) semiconductor for next generation electronics, due to its moderate bandgap size, high electron mobility and pronounced ambient stability. Meanwhile, it has been predicted that high-quality Bi2O2Se-related heterostructures may possess exotic physical phenomena, such as piezoelectricity and topological superconductivity. Herein, we report the first successful heteroepitaxial growth of Bi2O2Se films on SrTiO3 substrates via pulsed laser deposition (PLD) method. Films obtained under optimal conditions show an epitaxial growth with the c axis perpendicular to the film surface and the a and b axes parallel to the substrate. The growth mode transition to three-dimensional (3D) island from quasi-2D layer of the heteroepitaxial Bi2O2Se films on SrTiO3 (001) substrates is observed as prolonging deposition time of films. The maximum value of electron mobility reaches 160 cm2 V-1 s-1 at room temperature in a 70 nm thick film. The thickness dependent mobility provides evidence that interface-scattering is likely to be the limiting factor for the relatively low electron mobility at low temperature, implying that the interface engineering as an effective method to tune the low temperature electron mobility. Our work suggests the epitaxial Bi2O2Se films grown by PLD are promising for both fundamental study and practical applications.

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.

Akt plays indispensable roles during the first cell lineage differentiation of mouse.

The first cell lineage differentiation occurs during the development of mouse 8-cell embryo to blastocyst. Akt is a potent kinase whose role during blastocyst formation has not been elucidated. In the present study, immunofluorescence results showed that the Akt protein was specifically localized to the outer cells of the morula. Akt-specific inhibitor MK2206 significantly inhibited mouse blastocyst formation and resulted in decreased expression of the trophectoderm marker Cdx2 and led to granular distribution of ERα in the cytoplasm. Furthermore, knockdown of ERα by siRNA microinjection can also lead to a decrease in the development rate of mouse blastocysts, accompanied by a decrease in the expression level of Yap protein. We conclude that Akt may be indispensable for the first cell lineage differentiation of mouse.

Icariin protects mouse Leydig cell testosterone synthesis from the adverse effects of di(2-ethylhexyl) phthalate.

Infertility caused by environmental pollution is becoming a global problem, but an effective prevention or treatment is lacking. Icariin (ICA) is a flavonoid used in traditional Chinese medicine. The present study investigated the possible roles of ICA in preventing testicular dysfunction caused by di(2-ethylhexyl) phthalate (DEHP), one of the most studied environmental endocrine disruptors. Cultured mouse Leydig cells were pretreated with ICA and exposed to DEHP to determine ICA effects upon cell proliferation, reactive oxygen species (ROS) levels, mitochondrial membrane potential (Δψm), testosterone levels and the expression of transcription factor SF-1 and steroidogenic enzymes (CYP11, 3ß-HSD and 17ß-HSD), which play critical roles in androgen production. Our results showed that ICA reversed the adverse effect of DEHP on Leydig cell proliferation, and decreased ROS levels and elevated Δψm levels. Also, ICA promoted testosterone production and up-regulated the expression of SF-1 and steroidogenic enzymes. We investigated ICA actions in vivo, using male mice administrated DEHP followed by ICA. Exposure to DEHP decreased epididymal sperm counts and disrupted seminiferous tubules, and both of these effects were reversed by ICA treatment. These results showed that the mechanisms of ICA in protecting mouse testes against DEHP-induced damage involves the prevention of ROS accumulation and promotion of testosterone secretion.

Atypical GATA protein TRPS1 plays indispensable roles in mouse two-cell embryo.

Zygotic genome activation (ZGA) is one of the most critical events at the beginning of mammalian preimplantation embryo development (PED). The mechanisms underlying mouse ZGA remain unclear although it has been widely studied. In the present study, we identified that tricho-rhino-phalangeal syndrome 1 (TRPS1), an atypical GATA family member, is an important factor for ZGA in mouse PED. We found that the Trps1 mRNA level peaked at the one-cell stage while TRPS1 protein did so at the two/four-cell stage. Knockdown of Trps1 by the microinjection of Trps1 siRNA reduced the developmental rate of mouse preimplantation embryos by approximately 30%, and increased the expression of ZGA marker genes MuERV-L and Zscan4d via suppressing the expression of major histone markers H3K4me3 and H3K27me3. Furthermore, Trps1 knockdown decreased the expression of Sox2 but increased Oct4 expression. We conclude that TRPS1 may be indispensable for zygotic genome activation during mouse PED.

Vaginal nystatin versus oral fluconazole for the treatment for recurrent vulvovaginal candidiasis.

Recurrent vulvovaginal candidiasis (RVVC) is a common condition that can physically and psychologically impact patients. We compared the efficacy and safety of vaginal nystatin suppositories for 14 days each month versus standard oral fluconazole regimens for the treatment for RVVC. Patients (n = 293) were enrolled in the study from April 2010 to September 2013. After the initial therapy, the mycological cure rates were 78.3% (119/152) and 73.8% (104/141) in the nystatin group and fluconazole group, respectively (95% CI, 0.749-2.197, p > 0.05). The mycological cure rates at the end of maintenance therapy were 80.7% (96/119) and 72.7% (72/99) in the two groups, respectively (95% CI, 0.954-3.293, p > 0.05).The mycological cure rates at the end without treatment for 6 months were 81.25% (78/96) and 82.19% (60/73) in the two groups, respectively (95% CI, 0.427-2.066, p > 0.05). The mycological cure rates of RVVC caused by C. albicans were 84.0% (89/106) and 81.8% (99/121) in the two groups, respectively. The mycological cure rates of RVVC caused by C. glabrata were 64.3% (27/42) and 12.5% (2/16) in the two groups, respectively. The initial and 6-month maintenance therapy were successful in five of the nine patients in the nystatin group with RVVC caused by fluconazole-resistant Candida, whereas in the fluconazole group, initial therapy failed in all patients with RVVC caused by fluconazole-resistant Candida (n = 7). We conclude that both fluconazole and nystatin therapies are effective in treating RVVC. Nystatin may also be effective for the treatment for RVVC caused by C. glabrata or fluconazole-resistant Candida.