Charge doping in graphene on thermodynamically preferred BiFeO3(0001) polar surfaces.

For graphene/ferroelectric hybrid structures, the atomistic and electronic details of the interfaces are of crucial importance for charge doping in graphene. In this paper, we choose thermodynamically stable BiFeO3(0001) surfaces to explore the adsorption behavior and charge doping effect in a graphene/BiFeO3 system. By performing first-principles calculations, we find that both the adsorption behavior and charge doping effect show distinct characteristics for graphene adsorbed on the oppositely polarized BiFeO3(0001) surfaces. We predict that n-type doping and p-type charge doping occur in graphene on the positive and negative BiFeO3(0001) surfaces, respectively. The carrier density is estimated to be 1013 cm-2 orders of magnitude. Our results reveal that the graphene/BiFeO3 hybrid system is an intriguing candidate to make graphene-based field-effect transistors, whose p-n junctions can be made by patterning the domain structure of the BiFeO3 substrate. Moreover, the graphene/BFO hybrid structure may display an outstanding photovoltaic effect due to the combination of the bulk photovoltaic effect of the BFO substrate and the optical transparency of the graphene electrode.

Compassionate Use of Yuanjiang Decoction, a Traditional Chinese Medicinal Prescription, for Symptomatic Bradyarrhythmia.

Background: No effective medication is available for symptomatic bradyarrhythmia, particularly in low socioeconomic status (SES) population. Objective: To explore the safety and efficacy of Yuanjiang decoction, a traditional Chinese medicinal prescription, for symptomatic bradyarrhythmia on a compassionate-use basis. Methods: This compassionate-use study was conducted in Beijing, China between January 2019 and January 2020. Eligible participants were recruited and treated with Yuanjiang decoction (composed of 6 Chinese herbal medicines), 200 ml twice daily for 16 weeks. Analyses were done with the intention-to-treat (ITT) approach. The primary outcome measure was the proportion of participants who achieved a favorable treatment outcome at 16 weeks. Results: As of January 2020, 184 patients were included. After 16-weeks treatment, 12 participants were lost to contact while 21 participants were terminated from this study, with a drop-out rate of 17.93%. The most common treatment-related adverse events were xerostomia (6.52%), constipation (6.45%) and sleepiness (3.26%). The proportion of participants with favorable treatment outcome was 65.22% at 4 weeks, 59.78% at 8 weeks (OR: 1.11, 95% CI: 0.71-1.73), 61.41% at 12 weeks (OR: 1.16, 95% CI: 0.92-1.45) and 60.87% at 16 weeks (OR: 1.15, 95% CI: 0.98-1.35). In the multifactor regression analysis, the favorable treatment outcome at 16 weeks was significantly associated with completing at least 8 weeks treatment (OR: 2.053, 95% CI: 1.064-3.560), while unfavorable treatment outcome was significantly associated with an atrioventricular block (OR: 0.255, 95% CI: 0.083-0.784), current smoking (OR: 0.343, 95% CI: 0.027-0.487), and syncope in the month before treatment (OR: 0.321, 95%CI: 0.114-0.904). Conclusion: This compassionate-use study showed encouraging outcomes of treatment with Yuanjiang decoction, without serious adverse events. This study identified several key factors that may affect outcomes. These findings helped inform the design and assess the feasibility of a large-scale randomized clinical trial.

Thermodynamic Stability of BiFeO3 (0001) Surfaces from ab Initio Theory.

The relative stability of multiferroic BiFeO3 (0001) surfaces, which is the (111) facet in the pseudocubic notation, with different stoichiometry is systematically studied by using ab initio thermodynamic approach in order to obtain insights into the stable surface terminations. We predict that under most chemical potential conditions the thermodynamically favored terminations for the negative and positive surfaces are -Bi-O2 and -Fe-O3-Bi, respectively. The predicted difference in oxygen content between the negative and positive surfaces is consistent with experimental observations at the BiFeO3/metal interfaces ( Nat. Mater. , 2014 , 13 , 1019 , DOI: 10.1038/nmat4058 ; Adv. Mater. , 2015 , 27 , 6934 , DOI: 10.1002/adma.201502754 ). We determine the atomic geometries and electronic states as well as the magnetic properties for the negatively and positively polarized stable surfaces. Our results demonstrate that not only the stoichiometry and atomic geometries but also the electronic and magnetic properties of the BiFeO3 (0001) surfaces show strong dependence on the ferroelectric polarization direction. Therefore, we expect that the surface physical and chemical properties of the BiFeO3 (0001) surfaces can be easily tuned by an external electric field.