One of the characteristics of topological materials is their nontrivial Berry phase. Experimental determination of this phase largely relies on a phase analysis of quantum oscillations. We study the ...angular dependence of the oscillations in a Dirac material Formula: see text and observe a striking spin-zero effect (i.e., vanishing oscillations accompanied with a phase inversion). This indicates that the Berry phase in Formula: see text remains nontrivial for arbitrary field direction, in contrast with previous reports. The Zeeman splitting is found to be proportional to the magnetic field based on the condition for the spin-zero effect in a Dirac band. Moreover, it is suggested that the Dirac band in Formula: see text is likely transformed into a line node other than Weyl points for the field directions at which the spin zero occurs. The results underline a largely overlooked spin factor when determining the Berry phase from quantum oscillations.
Intensification of short‐duration rainfall extremes contributes to increased urban flood risk. Yet, it remains unclear how upper‐tail rainfall statistics could change with regional warming. Here, we ...characterize the non‐stationarity of rainfall extremes over durations of 1–24 hr for the rapidly developing coastal megalopolis of the Greater Bay Area, China. Using high‐resolution, multi‐source, merged and gridded data we observe greater increases in rainfall intensities over the north‐central part of the region compared with the southern coastal region. Our results show, for the first time, that urbanization nonlinearly increases rainfall intensities at different durations and return periods. Over short durations (≤3‐hr) and short return periods (2‐yr), urban areas have the greatest scaling rates (≥19.9%/°C). However, over longer durations (≥9‐hr) rural areas have greater scaling rates, with a lower degree of dependency on both durations and return periods.
Plain Language Summary
Short‐duration (sub‐daily) rainfall extremes are major drivers of flash floods and hence significant disruptions to society. Previous modeling and statistical studies show that urbanization intensifies short‐duration rainfall extremes. However, there has been less attention to regional variations in rates of rainfall intensification under a warming climate, particularly for extreme events with return periods that are comparable to or longer than the years of record. In this study, we investigate changes in rainfall extremes over the Greater Bay Area, China using long records of high‐resolution data merged from gauge networks, satellite observations, and reanalysis products. This enables us to evaluate changes in low‐frequency rainfall extremes (2‐ to 100‐yr return periods) over different land surfaces, under a warming climate. We find that increases in rainfall extremes significantly depend on the duration and return period of events, with the largest scaling occurring for short‐duration “nuisance” rainfall intensities over urban areas.
Key Points
Non‐stationarities of sub‐daily rainfall extremes over a coastal megalopolis exhibit marked land cover and duration dependencies
Urban areas show more prominent intensification of events over short durations and short return periods compared with rural areas
Rural areas show smaller nonstationary variabilities across durations and return periods and a lower peak scaling rate than urban areas
We determined a 3-D P-wave anisotropic tomography of the crust and uppermost mantle beneath North China Craton (NCC) using 107,976 P-wave arrival times from 16,073 local earthquakes recorded by 380 ...seismic stations. Our results show significant lateral heterogeneities beneath NCC. The lower crust and uppermost mantle beneath the North China Basin show widespread low-velocity anomalies which may reflect high-temperature materials caused by the late Mesozoic basaltic magmatism in the NCC. Low-velocity anomalies also exist beneath the Trans-North China Orogen, which may reflect asthenospheric upwelling since late Mesozoic. Large crustal earthquakes generally occurred in high-velocity zones in the upper to middle crust, while low-velocity and high-conductivity anomalies that may represent fluid-filled, fractured rock matrices exist in the lower crust to the uppermost mantle under the source zones of the large earthquakes. The crustal fluids may lead to the weakening of the seismogenic layer in the upper and middle crust and hence cause the large crustal earthquakes. The NW–SE P-wave fast velocity directions seem to be dominant in the uppermost mantle under the central parts of eastern NCC, suggesting that these mantle minerals were possibly regenerated but keep the original fossil anisotropy formed before the new lithospheric mantle was produced during the Mesozoic to Cenozoic.
► P-wave anisotropic tomography of North China Craton is determined. ► Large crustal earthquakes occurred in high-V zones in the upper to middle crust. ► Part of uppermost lithospheric mantle in eastern NCC may be regenerated. ► Some upper-mantle minerals in eastern NCC may keep their fossil anisotropy.
Relatively low mobility and thermal conductance create challenges for application of tungsten diselenide (WSe
) in high performance devices. Dielectric interface is of extremely importance for ...improving carrier transport and heat spreading in a semiconductor device. Here, by near-equilibrium plasma-enhanced chemical vapour deposition, we realize catalyst-free growth of poly-crystalline two-dimensional hexagonal-boron nitride (2D-BN) with domains around 20~ 200 nm directly on SiO
/Si, quartz, sapphire, silicon or SiO
/Si with three-dimensional patterns at 300 °C. Owing to the atomically-clean van-der-Walls conformal interface and the fact that 2D-BN can better bridge the vibrational spectrum across the interface and protect interfacial heat conduction against substrate roughness, both improved performance and thermal dissipation of WSe
field-effect transistor are realized with mobility around 56~ 121 cm
V
s
and saturated power intensity up to 4.23 × 10
W cm
. Owing to its simplicity, conformal growth on three-dimensional surface, compatibility with microelectronic process, it has potential for application in future two-dimensional electronics.
Currently, most arsenic (As) studies in populations are concerned with water-borne arsenicosis. However, residents in Xingren County of Guizhou Province, Southwest of China, represent a unique case ...of arsenicosis which is related to indoor combustion of high As-containing coal. This study aimed to assess the alterations of As levels and its risk factors in coal-borne arsenicosis residents during the past 20 years.
Four follow-up investigations in Xingren County were selected from the year 1998 to 2017, a total of 245, 272, 584, and 309 residents were involved in the four investigations, respectively. Local external environmental medium (coal, soil, water, air, rice, corn and chili peppers) and biological samples (urine, hair) were collected at each time of investigation for total As analysis. Sociodemographics and lifestyles variables were extracted from the questionnaire investigation. Both univariate and multivariate unconditional logistic regression models were performed to analyze the variation of risk factors for coal-borne arsenicosis.
A substantial reduction of total As levels was observed both in external environmental medium and biological samples in the unique coal-borne arsenicosis region, especially since the year 2006. In addition, age, duration of consuming high As-containing coal and smoking status were found to be the most significant risk factors for coal-borne arsenicosis during the past 20 years by both two different logistic regression models. Room ventilation and grain drying modes were no longer to be risk factors since 1998 survey. Annual household income had always been an important protective factor for coal-borne arsenicosis in recent 20 years by both two different logistic regression models. Grain storage modes had become significant protective factor in 2014 and 2017 survey. A certain correlation between sex, education and coal-borne arsenicosis was observed by univariate logistic regression model but no clear links were found by multivariate logistic regression model.
Considerable efforts to blocking As exposure from burning coal and As contaminated foods in this region are observed over the study period. Further practical health education programs may need to target individuals with long-term of As exposure, lower socioeconomic status and smoking in order to better prevent and control the occurrence and development of coal-borne arsenicosis.
•There was a substantial reduction of total As levels in the unique coal-borne arsenicosis region in the latest 10 years.•Age, duration of consuming high As-containing coal and smoking were always the risk factors for coal-borne arsenicosis.•Room ventilation and grain drying modes were no longer to be risk factors for coal-borne arsenicosis since 1998.•Annual household income had always been an important protective factor for coal-borne arsenicosis in recent 20 years.
Monitoring sea level changes and exploring their causes are of great significance for future climate change predictions and the sustainable development of mankind. This study uses multiple sets of ...satellite altimetry, satellite gravity, and ocean temperature and salinity data to study the basin-scale sea level budget (SLB) from 2005 to 2019. The basin-scale sea level rises significantly at a rate of 2.48–4.31 mm/yr, for which the ocean mass component is a main and stable contributing factor, with a rate of 1.77–2.39 mm/yr, while the steric component explains a ~1 mm/yr sea level rise in most ocean basins, except for the Southern Ocean. Due to the drift in Argo salinity since 2016, the residuals of basin-scale SLB are significant from 2016 to 2019. The worst-affected ocean is the Atlantic Ocean, where the SLB is no longer closed from 2005 to 2019. If halosteric sea level change trends from 2005 to 2015 are used to revise salinity data after 2016, the SLB on the ocean basin scale can be kept closed. However, the SLB on the global scale is still not closed and requires further study. Therefore, we recommend that Argo salinity products after 2016 should be used with caution.
Reintroduction has been successful in re-establishing several endangered wild animals in their historical habitats, including Père David's deer (
). Continuous monitoring of reintroduced individuals ...is essential for improving the sustainability of ex situ conservation efforts. Despite an increased recognition of the significance of the gut microbiome for animal health, the correlation between diet and the gut microbiome in
is unclear. In this study, 15 fresh fecal samples of
were collected from Tianjin Qilihai Wetland and the association between dietary and gut microbiota composition was evaluated. Microscopic observations showed that
relative density (RD = 0.3514),
(RD = 0.2662),
(RD = 0.1211), and
(RD = 0.1085) were the main dietary plants in the fecal samples. High-throughput 16S rRNA sequencing showed a predominance of the phyla Firmicutes and Proteobacteria and the genus
(26.53%) in the gut microbiota. The RD of
was significantly positively correlated with the abundance of Firmicutes (
= 0.005) and the genus
(
= 0.024). This study indicates a close association between food digestion and nutrient intake, providing basic monitoring data for the full reintroduction and recovery of wild
.
Reintroduction is an effective strategy in the conservation of endangered species under scientific monitoring. Intestinal flora plays an important role in the envir onmental adaptation of endangered ...Père David's deer (
). In this study, 34 fecal samples from
were collected from different habitats in Tianjin city of China to investigate differences in the intestinal flora under captive and semi-free-ranging conditions. Based on 16S rRNA high-throughput sequencing technology, a total of 23 phyla and 518 genera were obtained. Firmicutes was dominant in all individuals. At the genus level,
(13.05%) and
(8.94%) were dominant in captive individuals, while
(26.53%) and
(11.33%) were dominant in semi-free-ranging individuals. Alpha diversity results showed that the intestinal flora richness and diversity were significantly (
< 0.001) higher in captive individuals than in semi-free-ranging individuals. Beta diversity analysis also showed a significant difference (
= 0.001) between the two groups. In addition, some age- and sex-related genera such as
were identified. In summary, the structure and diversity of intestinal flora showed significant habitat variation. This is the first time an analysis has been undertaken of the structural differences of the intestinal flora in Père David's deer, under different habitats in the warm temperate zone, providing a reference basis for the conservation of endangered species.
The dose effect of radiation has long been a topic of concern, but the molecular mechanism behind it is still unclear. In this study, dried pea seeds were irradiated with 252Cf fission neutron ...source. Through analyzing the transcriptome and proteome of M1 generation pea (Pisum sativum L.) leaves, we studied the molecular rule and mechanism of neutron dose effect. Our results showed three important rules of global gene expression in the studied dose range. The rule closely related to the neutron absorbed dose at the transcription and translation levels is: the greater the difference in neutron absorbed dose between two radiation treatment groups, the greater the difference in differential expression between the two groups and the control group. We also obtained important sensitive metabolic pathways of neutron radiation, as well as related key genes. Furthermore, the overall molecular regulation mechanism of dose effect was revealed based on the main functional items obtained. Our research results can be applied to appropriate radiation dose estimation and agricultural production practice.
•Three important rules of global gene expression in the studied dose range were found.•The overall molecular regulation mechanism of neutron dose effect was revealed.•Phenylpropanoid biosynthesis is sensitive metabolic pathway for neutron radiation.•Carotenoid biosynthesis is downregulated metabolic pathway by neutron radiation.•Some related sensitive key genes of 4Gy and 6Gy neutron irradiation were identified.
Abstract
Ion migration and phase segregation, in mixed‐cation/anion perovskite materials, raises a bottleneck for its stability improvement in solar cells operation. Here, the synergetic effect of ...electric field and illumination on the phase segregation of Cs
0.05
FA
0.80
MA
0.15
Pb(I
0.85
Br
0.15
)
3
(CsFAMA) perovskite is demonstrated. CsFAMA perovskite with a CsPbBr
3
‐clusters passivated structure is realized, in which CsPbBr
3
‐clusters are located at the surface/interface of CsFAMA grains. This structure is realized by introducing a CsPbBr
3
colloidal solution into the CsFAMA precursor. It is found that CsPbBr
3
passivation greatly suppresses phase segregation in CsFAMA perovskite. The resultant passivated CsFAMA also exhibits a longer photoluminescence lifetime due to reduced defect state densities, produces highly efficient TiO
2
‐based planar solar cells with 20.6% power conversion efficiency and 1.195 V open‐circuit voltage. The optimized devices do not suffer from a fast burn‐in degradation and retain 90% of their initial performance at maximum power under one‐sun illumination at 25 °C (65 °C) exceeding 500 h (100 h) of continuous operation. This result represents the most stable output among CsFAMA solar cells in a planar structure with Spiro‐OMeTAD.
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