Mutual Information and Correlations across Topological Phase Transitions in Topologically Ordered Graphene Zigzag Nanoribbons.

Graphene zigzag nanoribbons, initially in a topologically ordered state, undergo a topological phase transition into crossover phases distinguished by quasi-topological order. We computed mutual information for both the topologically ordered phase and its crossover phases, revealing the following results: (i) In the topologically ordered phase, A-chirality carbon lines strongly entangle with B-chirality carbon lines on the opposite side of the zigzag ribbon. This entanglement persists but weakens in crossover phases. (ii) The upper zigzag edge entangles with non-edge lines of different chirality on the opposite side of the ribbon. (iii) Entanglement increases as more carbon lines are grouped together, regardless of the lines' chirality. No long-range entanglement was found in the symmetry-protected phase in the absence of disorder.

ESMO expert consensus statements on the management of EGFR mutant non-small-cell lung cancer.

The European Society for Medical Oncology (ESMO) held a virtual consensus-building process on epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancer in 2021. The consensus included a multidisciplinary panel of 34 leading experts in the management of lung cancer. The aim of the consensus was to develop recommendations on topics that are not covered in detail in the current ESMO Clinical Practice Guideline and where the available evidence is either limited or conflicting. The main topics identified for discussion were: (i) tissue and biomarkers analyses; (ii) early and locally advanced disease; (iii) metastatic disease and (iv) clinical trial design, patient's perspective and miscellaneous. The expert panel was divided into four working groups to address questions relating to one of the four topics outlined above. Relevant scientific literature was reviewed in advance. Recommendations were developed by the working groups and then presented to the entire panel for further discussion and amendment before voting. This manuscript presents the recommendations developed, including findings from the expert panel discussions, consensus recommendations and a summary of evidence supporting each recommendation.

Topological Gap States of Rectangular Armchair Ribbon.

We consider a rectangular graphene armchair ribbon with an excitation gap. The boundary of this system consists of two short zigzag edges and two long armchair edges. Within such a ribbon, topological gap states exist that are localized along the zigzag edges. The end charge of these states is an integer, which can be related to the Zak phase of the periodic armchair ribbon constructed from the rectangular armchair ribbon by connecting its zigzag edges together. In this paper, we provide an explicit analytical computation of the Zak phase of a periodic armchair ribbon, and show that its value is consistent with the integer end charges that are computed numerically. In the presence of a staggered potential, non-integer end charges are possible. We discuss its relation to the Zak phase.

[Molecular typing characterization of food-borne methicillin-resistant Staphylococcus aureus in China].

Objective: To analyses the antimicrobial resistance and molecular characterization of 21 MRSA isolates cultured from retail foods from different provinces in China, and evaluate the molecular typing methods. Methods: Twenty-one MRSA isolates were obtained from national foodborne pathogen surveillance network in 2012 (Chinese salad, n=3; milk, n=1; cake, n=2; rice, n=1; cold noodle, n=1; spiced beef, n=1; dumpling, n=1; packed meal, n=1; salad, n=1; raw pork, n=9). The antimicrobial resistance of 21 strains to 12 antimicrobial agents was tested by broth dilution method. Polymerase chain reaction (PCR) and DNA sequencing were performed to obtain the genetic types of MLST (ST) and spa typing. The clonal complex (CC) was assigned by eBURST soft and the MLVA type (MT) and MLVA complex (MC) were identified via the database of the MLVA website (http://www.mlva.net). SmaI pulsed-field gel electrophoresis (SmaⅠ-PFGE) was also carried out to obtain the PFGE patterns of 21 strains. The genetic diversity and discriminatory power of typing were calculated by the Simpson's index of diversity (diversity index, DI) to find out the best genotyping method for MRSA. Results: All MRSA isolates showed multi-drug resistance(MDR), and were resistant to oxacillin, benzylpenicillin, clindamycin and erythromycin, and 71.4% (15/21), 47.6% (10/21), 42.9% (9/21) and 28.6% (6/21) of the MRSA isolates were resistant to tetracycline, ciprofloxacin, trimethoprim/sulfamethoxazole and gentamicin, respectively. Moreover, one strain was found to be resistant to all three antimicrobials of levofloxacin, moxifloxacin and rifampicin. Great diversity was found in these food-associated MRSA (6 STs, 7 spa types, and 9 MTs). PFGE patterns were more diverse than those of other three molecular typing methods (19 pulse types). The index of diversity (DI) of PFGE, MLVA, spa typing and MLST was 0.99, 0.80, 0.73, and 0.61, respectively. Among the MRSA isolates, CC9-ST9-t899-MT929-MC2236 (PFGE Cluster Ⅴ) was the most prevalent clone, which were all cultured from raw pork (9 isolates). Besides, two MRSA were identified as CC59-ST338-t437-MT621-MC621 (PFGE Cluster Ⅳ). Different clone had their own resistance spectrum profiles. Conclusion: The food-borne MRSA isolates were all MDR in this study. Different clones had their own resistance spectrum profiles. MLVA represented a promising tool for molecular epidemiology tracing of MRSA in foodborne disease events.

Influence of pre-diagnostic cigarette smoking on colorectal cancer survival: overall and by tumour molecular phenotype.

BACKGROUND: Smoking is a risk factor for incident colorectal cancer (CRC); however, it is unclear about its influence on survival after CRC diagnosis. METHODS: A cohort of 706 CRC patients diagnosed from 1999 to 2003 in Newfoundland and Labrador, Canada, was followed for mortality and recurrence until April 2010. Smoking and other relevant data were collected by questionnaire after cancer diagnosis, using a referent period of '2 years before diagnosis' to capture pre-diagnosis information. Molecular analyses of microsatellite instability (MSI) status and BRAF V600E mutation status were performed in tumour tissue using standard techniques. Multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated with Cox proportional hazards regression, controlling for major prognostic factors. RESULTS: Compared with never smokers, all-cause mortality (overall survival, OS) was higher for current (HR: 1.78; 95% CI: 1.04-3.06), but not for former (HR: 1.06; 95% CI: 0.71-1.59) smokers. The associations of cigarette smoking with the study outcomes were higher among patients with ≥40 pack-years of smoking (OS: HR: 1.72; 95% CI: 1.03-2.85; disease-free survival (DFS: HR: 1.99; 95% CI: 1.25-3.19), those who smoked ≥30 cigarettes per day (DFS: HR: 1.80; 95% CI: 1.22-2.67), and those with microsatellite stable (MSS) or MSI-low tumours (OS: HR: 1.38; 95% CI: 1.04-1.82 and DFS: HR: 1.32; 95% CI: 1.01-1.72). Potential heterogeneity was noted for sex (DFS HR: 1.68 for men and 1.01 for women: P for heterogeneity=0.04), and age at diagnosis (OS: HR: 1.11 for patients aged <60 and 1.69 for patients aged ≥60: P for heterogeneity=0.03). CONCLUSIONS: Pre-diagnosis cigarette smoking is associated with worsened prognosis among patients with CRC.

Phase diagram and crossover phases of topologically ordered graphene zigzag nanoribbons: role of localization effects.

We computed the phase diagram of zigzag graphene nanoribbons as a function of on-site repulsion, doping, and disorder strength. The topologically ordered phase undergoes topological phase transitions into crossover phases, which are new disordered phases with non-universal topological entanglement entropy that exhibits significant variance. We explored the nature of non-local correlations in both the topologically ordered and crossover phases. In the presence of localization effects, strong on-site repulsion and/or doping weaken non-local correlations between the opposite zigzag edges of the topologically ordered phase. In one of the crossover phases, bothe-/2solitonic fractional charges and spin-charge separation were absent; however, charge-transfer correlations between the zigzag edges were possible. Another crossover phase contains solitonice-/2fractional charges but lacks charge transfer correlations. We also observed properties of non-topological, strongly disordered, and strongly repulsive phases. Each phase on the phase diagram exhibits a different zigzag-edge structure. Additionally, we investigated the tunneling of solitonic fractional charges under an applied voltage between the zigzag edges of undoped topologically ordered zigzag ribbons, and found that it may lead to a zero-bias tunneling anomaly.

Optical properties of Dirac electrons in a parabolic well.

A single electron transitor may be fabricated using qunatum dots. A good model for the confinement potential of a quantum dot is a parabolic well. Here we consider such a parabolic dot made of graphene. Recently, we found counter intuitively that resonant quasi-boundstates of both positive and negative energies exist in the energy spectrum. The presence of resonant quasi-boundstates of negative energies is a unique property of massless Dirac fermions. As magnetic field B gets smaller the energy width of these states become broader and for sufficiently weak value of B resonant quasi-bound states disappear into a quasi-continuum. In the limit of small B resonant and nonresonant states transform into discrete anomalous states with a narrow probability density peak inside the well and another broad peak under the potential barrier. In this paper we compute the optical strength between resonant quasi-bound states as a function of B, and investigate how the signature of resonant quasi-bound states of Dirac electrons may appear in optical measurements.

[Association between volatile organic compounds and mortality risk of stroke].

Objective: To investigate the effect of volatile organic compounds (VOCs) exposure in the atmosphere on the risk of daily death from stroke in Guangzhou. Methods: Daily average concentrations of twelve atmospheric VOCs, meteorological factors, and daily deaths for stroke and its subtypes (including ischemic and hemorrhagic stroke) in Guangzhou from 2020 to 2021 were collected. The time-series Poisson generalized additive model was established to analyze the relationship between daily average concentrations of atmospheric VOCs and daily mortality from a stroke on different lag days. The season, gender, and age group further performed stratification analysis. Results: Toluene and n-pentane were associated with a higher mortality risk from stroke and its subtypes. For each interquartile range (IQR) increment in toluene concentration at lag0- 1 days, the RRs for mortality from stroke and hemorrhagic stroke were 1.060 (95%CI: 1.036-1.085) and 1.071 (95%CI: 1.030-1.113), respectively. For each IQR increment in n-pentane concentration, the RR for mortality from ischemic stroke was 1.064 (95%CI: 1.030-1.099). The effect estimates of VOCs may be higher during the cold season and among women and people aged ≥75 years. For each IQR increment in toluene concentration, the RRs for mortality risk of stroke in the cold season and women were 1.099 (95%CI: 1.056-1.143) and 1.085 (95%CI: 1.050-1.120), respectively. For n-pentane, the RR for death risk of stroke in people aged ≥75 years old was 1.072 (95%CI: 1.036-1.109). Results of sensitivity analysis showed that the effect estimates fluctuated less when PM2.5 and O3 were separately introduced for the two-pollutant model, as well as changing the degrees of freedom for covariates. Conclusions: This study suggests that VOCs may be an independent risk factor for daily mortality from stroke. Moreover, Toluene presented the most significant health impact.

Can a repulsive potential in graphene have boundstates in a magnetic field?

We consider Klein tunneling through a repulsive and cylindrical potential with range R and strength V. Recently it was found that, in the strong coupling regime R/l < 1, the repulsive potential can have bound states peaked inside the potential with tails extending over l mean square root of 2(N+1), where N is Landau level (LL) index and f is the magnetic length. The presence of these bound states is a consequence of a subtle interplay between Klein tunneling and quantization effect of magnetic fields. Because of the presence of these bound states the effective coupling between the repulsive potential and an electron can be attractive. Here we show that this effect is a consequence of singular interaction between the repulsive potential and an electron that cannot be captured in perturbative approaches.

Room-temperature charge stability modulated by quantum effects in a nanoscale silicon island.

We report on transport measurement performed on a room-temperature-operating ultrasmall Coulomb blockade devices with a silicon island of sub5 nm. The charge stability at 300K exhibits a substantial change in slopes and diagonal size of each successive Coulomb diamond, but remarkably its main feature persists even at low temperature down to 5.3K except for additional Coulomb peak splitting. This key feature of charge stability with additional fine structures of Coulomb peaks are successfully modeled by including the interplay between Coulomb interaction, valley splitting, and strong quantum confinement, which leads to several low-energy many-body excited states for each dot occupancy. These excited states become enhanced in the sub5 nm ultrasmall scale and persist even at 300K in the form of cluster, leading to the substantial modulation of charge stability.

[Research progress in association between endothelial dysfunction and periodontitis].

Vascular endothelium formulates the basic defense against cardiovascular diseases. Multiple factors such as inflammatory factors, oxidative stress and biological factors can cause endothelial dysfunction and be involved in the formation and development of cardiovascular diseases. In studies of recent years, accumulated evidences showed that periodontitis was an independent risk factor for cardiovascular events, and was related to vascular endothelial dysfunction. Periodontal therapy could improve the vascular endothelial function. In this paper, the epidemiological evidences of associations between periodontitis and vascular endothelial dysfunction in recent years were listed, and the possible mechanisms of periodontitis aggravating endothelial dysfunction were analyzed. The importance of periodontal intervention in improving endothelial function was emphasized. This will provide new ideas for further study about the relationship between periodontitis and cardiovascular diseases and for the prevention and treatment strategies.

New disordered anyon phase of doped graphene zigzag nanoribbon.

We investigate interacting disordered zigzag nanoribbons at low doping, using the Hubbard model to treat electron interactions within the density matrix renormalization group and Hartree-Fock method. Extra electrons that are inserted into an interacting disordered zigzag nanoribbon divide into anyons. Furthermore, the fractional charges form a new disordered anyon phase with a highly distorted edge spin density wave, containing numerous localized magnetic moments residing on the zigzag edges, thereby displaying spin-charge separation and a strong non-local correlation between the opposite zigzag edges. We make the following new predictions, which can be experimentally tested: (1) In the low doping case and weak disorder regime, the soft gap in the tunneling density of states is replaced by a sharp peak at the midgap energy with two accompanying peaks. The [Formula: see text] fractional charges that reside on the boundary of the zigzag edges are responsible for these peaks. (2) We find that the midgap peak disappears as the doping concentration increases. The presence of [Formula: see text] fractional charges will be strongly supported by the detection of these peaks. Doped zigzag ribbons may also exhibit unusual transport, magnetic, and inter-edge tunneling properties.

Dirac electrons of a split-gate Hall bar.

In this work we study several unusual properties of Klein tunneling through the abrupt and flat barriers of a split-gate Hall bar system of graphene. We show that Klein tunneling of Dirac electrons can be rather strong in such a system, and that a significant electron density can be present under the barrier. It can be shown that the probability wavefunctions for large angular momenta are identical to the probability wavefunctions of the same angular momenta in the absence of the potential barrier, i.e., it is as if the barrier does not exist and the Klein tunneling is complete. This is a unique effect in a magnetic field. We propose that STM measurements may be used to detect the presence of such a density. We have also investigated drift velocity of electrons as the center of probability wavefunction varies from outside to inside of the flat potential barrier, and find a significant deviation from the semiclassical result.

Coupling of surface and lowest Landau level states in a rectangular graphene dot.

A rectangular graphene dot with two zigzag edges and two armchair edges have electronic states in the presence of a magnetic field that are localized on the zigzag edges with non zero values of the wavefunction inside the dot. We have investigated the dependence of these wavefunctions on the size of the dot, and explain the physical origin of them in terms of surface and the lowest Landau level (LLL) states of infinitely long nanoribbons. We find that the armchair edges play a crucial role by coupling the surface and LLL states.

Soliton Fractional Charges in Graphene Nanoribbon and Polyacetylene: Similarities and Differences.

An introductory overview of current research developments regarding solitons and fractional boundary charges in graphene nanoribbons is presented. Graphene nanoribbons and polyacetylene have chiral symmetry and share numerous similar properties, e.g., the bulk-edge correspondence between the Zak phase and the existence of edge states, along with the presence of chiral boundary states, which are important for charge fractionalization. In polyacetylene, a fermion mass potential in the Dirac equation produces an excitation gap, and a twist in this scalar potential produces a zero-energy chiral soliton. Similarly, in a gapful armchair graphene nanoribbon, a distortion in the chiral gauge field can produce soliton states. In polyacetylene, a soliton is bound to a domain wall connecting two different dimerized phases. In graphene nanoribbons, a domain-wall soliton connects two topological zigzag edges with different chiralities. However, such a soliton does not display spin-charge separation. The existence of a soliton in finite-length polyacetylene can induce formation of fractional charges on the opposite ends. In contrast, for gapful graphene nanoribbons, the antiferromagnetic coupling between the opposite zigzag edges induces integer boundary charges. The presence of disorder in graphene nanoribbons partly mitigates antiferromagnetic coupling effect. Hence, the average edge charge of gap states with energies within a small interval is e / 2 , with significant charge fluctuations. However, midgap states exhibit a well-defined charge fractionalization between the opposite zigzag edges in the weak-disorder regime. Numerous occupied soliton states in a disorder-free and doped zigzag graphene nanoribbon form a solitonic phase.

Soliton fractional charge of disordered graphene nanoribbon.

We investigate the properties of the gap-edge states of half-filled interacting disordered zigzag graphene nanoribbons, and find that the midgap states can display a quantized fractional charge of 1/2. These gap-edge states can be represented by topological kinks with their site probability distribution divided between the left and right zigzag edges with different chiralities. In addition, there are numerous spin-split gap-edge states, similar to those in a Mott-Anderson insulator.

Strongly exchange-coupled and surface-state-modulated magnetization dynamics in Bi2Se3/yttrium iron garnet heterostructures.

Harnessing the spin-momentum locking of topological surface states in conjunction with magnetic materials is the first step to realize novel topological insulator-based devices. Here, we report strong interfacial coupling in Bi2Se3/yttrium iron garnet (YIG) bilayers manifested as large interfacial in-plane magnetic anisotropy (IMA) and enhancement of damping probed by ferromagnetic resonance. The interfacial IMA and damping enhancement reaches a maximum when the Bi2Se3 film approaches its two-dimensional limit, indicating that topological surface states play an important role in the magnetization dynamics of YIG. Temperature-dependent ferromagnetic resonance of Bi2Se3/YIG reveals signatures of the magnetic proximity effect of TC as high as 180 K, an emerging low-temperature perpendicular magnetic anisotropy competing the high-temperature IMA, and an increasing exchange effective field of YIG steadily increasing toward low temperature. Our study sheds light on the effects of topological insulators on magnetization dynamics, essential for the development of topological insulator-based spintronic devices.

High-quality thulium iron garnet films with tunable perpendicular magnetic anisotropy by off-axis sputtering - correlation between magnetic properties and film strain.

Thulium iron garnet (TmIG) films with perpendicular magnetic anisotropy (PMA) were grown on gadolinium gallium garnet (GGG) (111) substrates by off-axis sputtering. High-resolution synchrotron radiation X-ray diffraction studies and spherical aberration-corrected scanning transmission electron microscope (Cs-corrected STEM) images showed the excellent crystallinity of the films and their sharp interface with GGG. Damping constant of TmIG thin film was determined to be 0.0133 by frequency-dependent ferromagnetic resonance (FMR) measurements. The saturation magnetization (Ms) and the coercive field (Hc) were obtained systematically as a function of the longitudinal distance (L) between the sputtering target and the substrate. A 170% enhancement of PMA field (H⊥) was achieved by tuning the film composition to increase the tensile strain. Moreover, current-induced magnetization switching on a Pt/TmIG structure was demonstrated with an ultra-low critical current density (jc) of 2.5 × 106 A/cm2, an order of magnitude smaller than the previously reported value. We were able to tune Ms, Hc and H⊥ to obtain an ultra-low jc of switching the magnetization, showing the great potential of sputtered TmIG films for spintronics.

Properties of BK(Ca) channels in oral keratinocytes.

Keratinocytes are important for epithelial antimicrobial barrier function. The activity of ion channels can affect the proliferation of keratinocytes. Little is known about Ca2+-activated K+ currents in these cells. Ion currents in normal human oral keratinocytes were characterized with a patch-clamp technique. In whole-cell configuration, depolarizing pulses evoked K+ outward currents (I(K)) in oral keratinocytes. Iberiotoxin (200 nM) and paxilline (1 microM) suppressed I(K); however, neither apamin (200 nM) nor 5-hydroxydecanoate (30 microM) had any effects on it. Caffeic acid phenethyl ester, a compound of honeybee propolis, increased I(K) with an EC50 value of 12.8 +/- 1.2 microM. In inside-out patches, a BK(Ca) channel was observed in keratinocytes, but not in oral squamous carcinoma (OCE-M1) cells. Caffeic acid phenethyl ester or cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate applied to the intracellular surface of a detached patch increased BK(Ca)-channel activity. The results demonstrate that the properties of BK(Ca) channels in normal human oral keratinocytes are similar to those described in other types of cells. Caffeic acid derivatives can also stimulate BK(Ca)-channel activity directly.