Proton-assisted growth of ultra-flat graphene films.

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 transistors1-10. However, wrinkles invariably form during growth because of the strong coupling to the substrate, and these limit the large-scale homogeneity of the film1-4,11,12. 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 penetration13-17 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.

Iron Vacancy Tunable Superconductor-Insulator Transition in FeSe/SrTiO_{3} Monolayer.

The Fe_{4}Se_{5} with a sqrt[5]×sqrt[5] Fe vacancy order is suggested to be a Mott insulator and the parent state of bulk FeSe superconductor. The iron vacancy ordered state has been considered as a Mott insulator and the parent compound of bulk FeSe-based superconductors. However, for the superconducting FeSe/SrTiO_{3} monolayer (FeSe/STO) with an interface-enhanced high transition temperature (T_{c}), the electronic evolution from its Fe vacancy ordered parent phase to the superconducting state, has not been explored due to the challenge to realize an Fe vacancy order in the FeSe/STO monolayer, even though important to the understanding of superconductivity mechanism. In this study, we developed a new method to generate Fe vacancies within the FeSe/STO monolayer in a tunable fashion, with the assistance of atomic hydrogen. As a consequence, an insulating sqrt[5]×sqrt[5] Fe vacancy ordered monolayer is realized as the parent state. By using scanning tunneling microscopy and scanning tunneling spectroscopy, the spectral evolution from superconductivity to insulator is fully characterized. Surprisingly, a prominent spectral weight transfer occurs, thus implying a strong electron correlation effect. Moreover, the Fe vacancy induced insulating gap exhibits no Mott gap-like features. This work provides new insights in understanding the high-T_{c} superconductivity in FeSe/STO monolayer.

Bavachin protects against diet-induced hepatic steatosis and obesity in mice.

Non-alcoholic fatty liver disease (NAFLD) is a major health concern worldwide, and the incidence of metabolic disorders associated with NAFLD is rapidly increasing because of the obesity epidemic. There are currently no approved drugs that prevent or treat NAFLD. Recent evidence shows that bavachin, a flavonoid isolated from the seeds and fruits of Psoralea corylifolia L., increases the transcriptional activity of PPARγ and insulin sensitivity during preadipocyte differentiation, but the effect of bavachin on glucose and lipid metabolism remains unclear. In the current study we investigated the effects of bavachin on obesity-associated NAFLD in vivo and in vitro. In mouse primary hepatocytes and Huh7 cells, treatment with bavachin (20 µM) significantly suppressed PA/OA or high glucose/high insulin-induced increases in the expression of fatty acid synthesis-related genes and the number and size of lipid droplets. Furthermore, bavachin treatment markedly elevated the phosphorylation levels of AKT and GSK-3ß, improving the insulin signaling activity in the cells. In HFD-induced obese mice, administration of bavachin (30 mg/kg, i.p. every other day for 8 weeks) efficiently attenuated the increases in body weight, liver weight, blood glucose, and liver and serum triglyceride contents. Moreover, bavachin administration significantly alleviated hepatic inflammation and ameliorated HFD-induced glucose intolerance and insulin resistance. We demonstrated that bavachin protected against HFD-induced obesity by inducing fat thermogenesis and browning subcutaneous white adipose tissue (subWAT). We revealed that bavachin repressed the expression of lipid synthesis genes in the liver of obese mice, while promoting the expression of thermogenesis, browning, and mitochondrial respiration-related genes in subWAT and brown adipose tissue (BAT) in the mice. In conclusion, bavachin attenuates hepatic steatosis and obesity by repressing de novo lipogenesis, inducing fat thermogenesis and browning subWAT, suggesting that bavachin is a potential drug for NAFLD therapy.

Rewiring the native methanol assimilation metabolism by incorporating the heterologous ribulose monophosphate cycle into Methylorubrum extorquens.

Methanol is assimilated through the serine cycle to generate acetyl-CoA without carbon loss. However, a highly active serine cycle requires high consumption of reducing equivalents and ATP, thereby leading to the impaired efficiency of methanol conversion to reduced chemicals. In the present study, a genome-scale flux balance analysis (FBA) predicted that the introduction of the heterologous ribulose monophosphate (RuMP) cycle, a more energy-efficient pathway for methanol assimilation, could theoretically increase growth rate by 31.3% for the model alphaproteobacterial methylotroph Methylorubrum extorquens AM1. Based on this analysis, we constructed a novel synergistic assimilation pathway in vivo by incorporating the RuMP cycle into M. extroquens metabolism with the intrinsic serine cycle. We demonstrated that the operation of the synergistic pathway could increase cell growth rate by 16.5% and methanol consumption rate by 13.1%. This strategy rewired the central methylotrophic metabolism through adjusting core gene transcription, leading to a pool size increase of C2 to C5 central intermediates by 1.2- to 3.6-fold and an NADPH cofactor improvement by 1.3-fold. The titer of 3-hydroxypropionic acid (3-HP), a model product in the newly engineered chassis of M. extorquens AM1, was increased to 91.2 mg/L in shake-flask culture, representing a 3.1-fold increase compared with the control strain with only the serine cycle. The final titer of 3-HP was significantly improved to 0.857 g/L in the fed-batch bioreactor, which was more competitive compared with the other 3-HP producers using methane and CO2 as C1 sources. Collectively, our current study demonstrated that engineering the synergistic methanol assimilation pathway was a promising strategy to increase the carbon assimilation and the yields of reduced chemicals in diverse host strains for C1 microbial cell factories.

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

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 Td-WTe2 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.

Eco-efficiency evaluation model: a case study of the Yangtze River Economic Belt.

After the concept of ecological efficiency (eco-efficiency) was put forward and constantly supplemented, it generally refers to the maximization of economic benefits with minimum energy consumption and environmental damage. In a new eco-efficiency model proposed by this paper, the input indexes take into account the consumption of capital, human, resources and energy, and the environmental load caused by them. The output indexes take into account GDP, income, and tax revenue. An optimal weighted cross-evaluation efficiency (OWCE) model based on data standardization is proposed, by improving the traditional data envelopment models of CCR and BCC. The OWCE model not only objectively weights but also unifies the comparison scale, and facilitates the establishment of the super-efficiency decomposition model, which is conducive to further exploring the reasons for the difference of eco-efficiency in various regions. Empirically, the eco-efficiencies of 11 provinces (municipalities) along the Yangtze River Economic Belt (YREB) were analyzed based on the data from 2008 to 2019. The results show that there has been a serious imbalance in the 11 provinces, showing a trend of high in the east and low in the west, although the eco-efficiency has been improving continuously in the past 10 years. Shanghai, Zhejiang, and Jiangsu, which are located in the traditional Yangtze River lower delta region, are the top in terms of eco-efficiency, among which Shanghai ranks the first place with absolute advantage, and also is far ahead in sub-efficiencies of basic input, energy consumption, capital and human input, and environmental cost. Geographical location, especially whether it is close to the ocean, and the length of river flow have a certain positive impact on eco-efficiency. Through in-depth analysis, high-energy consumption, high pollution, and low economic output are the main reasons for low eco-efficiency in the middle and upper reaches of the Yangtze River.

Historical trends of breast cancer burden attributable to metabolic factors among Chinese women, 1990-2019: A population-based epidemiological study.

BACKGROUND:  This study aims to analyze breast cancer burden attributable to high body mass index (BMI) and high fasting plasma glucose (FPG) in China from 1990 to 2019. METHODS: Data were obtained from the Global Burden of Disease (GBD) study 2019. Deaths and disability-adjusted life years (DALYs) were used for attributable burden, and age-period-cohort (APC) model was used to evaluate the independent effects of age, period and birth cohort. RESULTS: In 2019, the age-standardized mortality and DALY rates of breast cancer attributable to high BMI were 1.107 (95% UI: 0.311, 2.327) and 29.990 (8.384, 60.713) per 100 000, and mortality and DALY rates attributable to high FPG were 0.519 (0.095, 1.226) and 13.662 (2.482, 32.425) per 100 000. From 1990 to 2019, the age-standardized mortality and DALY rates of breast cancer attributable to high BMI increased by 1.192% and 1.180%, and the trends of high FPG were not statistically significant. The APC results showed that the age effects of high BMI and high FPG-mortality and DALY rates increased, with the highest rates in the age group over 80 years. The birth cohort effects of high BMI showed "inverted V" shapes, while high FPG showed downward trends. CONCLUSIONS: Age was the main reason for the increase of attributable burden, and postmenopausal women were the high-risk groups. Therefore, targeted prevention measures should be developed to improve postmenopausal women's awareness and effectively reduce the prevalence of obesity and diabetes, thereby reducing the breast cancer burden caused by metabolic factors in China.

Management of granulomatous lobular mastitis: an international multidisciplinary consensus (2021 edition).

Granulomatous lobular mastitis (GLM) is a rare and chronic benign inflammatory disease of the breast. Difficulties exist in the management of GLM for many front-line surgeons and medical specialists who care for patients with inflammatory disorders of the breast. This consensus is summarized to establish evidence-based recommendations for the management of GLM. Literature was reviewed using PubMed from January 1, 1971 to July 31, 2020. Sixty-six international experienced multidisciplinary experts from 11 countries or regions were invited to review the evidence. Levels of evidence were determined using the American College of Physicians grading system, and recommendations were discussed until consensus. Experts discussed and concluded 30 recommendations on historical definitions, etiology and predisposing factors, diagnosis criteria, treatment, clinical stages, relapse and recurrence of GLM. GLM was recommended as a widely accepted definition. In addition, this consensus introduced a new clinical stages and management algorithm for GLM to provide individual treatment strategies. In conclusion, diagnosis of GLM depends on a combination of history, clinical manifestations, imaging examinations, laboratory examinations and pathology. The approach to treatment of GLM should be applied according to the different clinical stage of GLM. This evidence-based consensus would be valuable to assist front-line surgeons and medical specialists in the optimal management of GLM.

Global burden of thyroid cancer and its attributable risk factors in 204 countries and territories from 1990 to 2019.

BACKGROUND: To investigate the burden of thyroid cancer and its attributable risk factors in 204 countries and territories during 30 years. METHODS: We extracted data from the Global Burden of Disease (GBD) 2019 database, including incidence, mortality, disability-adjusted life-years (DALYs), and the attributable risk factors of thyroid cancer from 1990 to 2019. Estimated annual percentage changes (EAPC) were calculated to assess the changes in age-standardized incidence rate (ASIR), age-standardized mortality rate (ASMR), and age-standardized DALYs rate (ASDR). We also examined the associations between cancer burden and the sociodemographic index (SDI). RESULTS: The global new cases, death, and DALYs of thyroid cancer in 2019 were 233 847 (95% UI: 211 637-252 807), 45 576 (95% UI: 41 290-48 775), and 1 231 841 (95% UI: 1 113 585-1 327 064), respectively. From 1990 to 2019, the ASIR of thyroid cancer showed an upward trend (EAPC = 1.25), but ASMR (EAPC = -0.15) and ASDR (EAPC = -0.14) decreased. The burden of thyroid cancer varied at regional and national levels, but the association between ASIR and SDI was positive. We found that the burden of thyroid cancer was mainly concentrated in females and that the age of onset tended to be younger. The proportion of DALYs from thyroid cancer attributable to high body-mass index was higher in high SDI regions, especially in males. CONCLUSIONS: The global incidence of thyroid cancer has continued to increase in the past three decades. The high body-mass index as an important risk factor for thyroid cancer deserves greater attention, especially in high SDI regions.

Direct Growth of van der Waals Tin Diiodide Monolayers.

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 SnI2 monolayer is successfully fabricated with a new structure. Scanning tunneling microscopy/spectroscopy characterization, as corroborated by the density functional theory calculation, indicates that this SnI2 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 SnI2 bilayer. This study provides a new semiconducting 2D material that is promising as a building block in future electronics/optoelectronics.

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

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.

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

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.

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

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.

Observation of Coulomb gap in the quantum spin Hall candidate single-layer 1T'-WTe2.

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'-WTe2 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 (EF). The opening of the Coulomb gap can efficiently diminish the bulk state at the EF and supports the observation of the quantized conduction of topological edge states.