Search

Magnetism in two-dimensional (2D) materials has attracted much attention recently. However, intrinsic magnetic 2D materials are rare and mostly unstable in ambient. Although heteroatom doping can introduce magnetism, the basic property especially the electrical-magnetic coupling property has been rarely revealed. Herein, both iron (Fe)-doped and vanadium (V)-doped MoS2 films were grown by chemical vapor deposition. Through studying the structure and electrical property of Fe-doped and V-doped MoS2, it was found that both Fe and V doping would decrease the electron concentration, exhibiting a p-type doping effect. Significantly, V-doped MoS2 displays a p-type conduction behavior. Although the carrier mobility decreases after heteroatom doping, both Fe and V doping could endow MoS2 with magnetism, in which the transfer curves of both MoS2 transistors exhibit a strong magnetic-dependent behavior. It is found that the magnetic response of Fe-doped MoS2 can be tuned from ~0.2 ​nA/T to ~1.3 ​nA/T, with the tunability much larger than that of V-doped MoS2. At last, the magnetic mechanism is discussed with the local magnetic property performed by magnetic force microscopy. The typical morphology-independent magnetic signal demonstrates the formed magnetic domain structure in Fe-doped MoS2. This study opens new potential to design novel magnetic-electrical devices.

ABSTRACT Purpose: The rat cervicitis model was established with 20% phenol glue to explore the therapeutic effect of Kangfuxiaomi shuan II on rat cervicitis and its mechanism. Methods: After modeling, the rats were treated with Shuangzuotai suppository (37.84 mg/kg), Kangfuxiaoyan shuan (205.6 mg/kg) and Kangfuxiaomi shuan II (40, 80, 160 mg/kg). The histopathological changes and injury degree of cervix in rats were evaluated by vulvar inflammation score and organ index. The therapeutic effect of Kangfuxiaomi shuan II on cervicitis was evaluated by detecting the levels of copper-protein (CP), C-reactive protein (CRP), Rat interleukin 6 (IL-6), superoxide dismutase (SOD) and malondialdehyde (MDA) in serum and epidermal growth factor (EGF), cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in cervical tissue. Results: Compared with the model group, the vulvar inflammation score and cervical index of rats in other groups decreased significantly (P

Winter construction in seasonally frozen soil areas is inevitable. The variation of ambient temperature causes the freeze-thaw of the filling soils and its impact is significant, and whether the countermeasures can be effectively established and adopted is particularly important for the management and control of the construction quality of the project. This paper conducts systematic research based on the winter construction process of the dam core wall of the Lianghekou Hydropower Station, which is the third highest earth-core rockfill dam in the world under construction. The results show that for the construction site in the seasonally frozen soil area, there is a development process of the short-term frozen soils for the filling soils under the environment with low temperature in winter. The soil underwent a high-frequency freeze-thaw process wherein it was frozen at night and completely thawed during the day. During the freezing process, a large number of thin-layered segregated ice developed inside the soil to form a thin-layered or integral cryostructure, which will have an adverse effect on the engineering properties and the quality of the filling soils. And, the field tests demonstrate that the filling compaction degree of the frozen soils is difficult to meet the designed requirements. In order to effectively cope with the adverse effect of the freeze-thaw on the construction quality during the construction process, based on the analysis of the freeze-thaw characteristics of soils and its influence, and the energy exchange process of soils on-site, the principles and methods for establishing the freeze prevention system during the winter construction process are established, and a comprehensive monitoring system suitable for on-site is established in this paper. This research will provide an important reference for the scientific management and efficiency improvement of the winter construction process of the dams in cold regions.

Monitoring the dynamics of atmospheric CO2 is crucial for enhancing comprehension of the carbon cycle. Using column‐averaged dry‐air mole fraction of CO2 (XCO2) data collected by the Orbiting Carbon Observatory (OCO)‐2 and OCO‐3 satellites during 2020–2021, this study explored seasonal and diurnal variations in XCO2 characteristics in typical land cover biomes in China, and investigated their relationships with meteorological drivers. Results showed that XCO2 products retrieved by OCO‐2 and OCO‐3 have good agreement with Total Carbon Column Observing Network measurements, with average deviations of 0.8 and 1.2 ppm, respectively. The satellite observations revealed XCO2 hotpots located mainly in central and eastern China, and areas of low XCO2 values in western China, with a seasonal curve that was highest (lowest) in spring (summer). The largest seasonal cycle amplitude (∼9 ppm) of XCO2 was observed in forest areas, highlighting its key role in carbon exchange. Additionally, XCO2 was found to have a near‐sinusoidal diurnal pattern, characterized by rapid decrease in the early morning as photosynthesis resumed after sunrise, as indicated by the sun‐induced chlorophyll fluorescence (SIF), a peak at around midday, and subsequent decrease as SIF increased after mid‐afternoon. Urban regions had the highest diurnal cycle amplitude (∼6 ppm) among biomes. Statistical analyses revealed seasonal shift and nonlinear variation in the relationships between XCO2 and meteorological variables, suggesting that CO2 uptake is influenced by favorable humidity conditions. These relationships also provide insight into the sensitivity and adaptability of XCO2 to meteorological factors in diverse ecosystems such as savanna and grassland. Plain Language Summary: Measuring CO2 concentrations helps us gain better understanding of the carbon cycle in the context of climate change. China is among the world's main emitters of carbon and it has pledged to achieve carbon neutrality. To create effective strategies for the mitigation of atmospheric CO2, it is important to investigate the CO2 dynamics on multiple time scales. Using observations from the OCO‐2 and OCO‐3 carbon‐monitoring satellites, we characterized the seasonal and diurnal variations in column‐averaged abundance of CO2 (XCO2) across biomes and examined the impact of meteorological factors. Our findings revealed a near‐sinusoidal pattern in the hourly variation of XCO2 over biomes, and suggested XCO2 seasonal variability varies among them, with maximum seasonal variability for forests (∼9 ppm), and the maximum diurnal variability for urban regions (∼6 ppm). Furthermore, meteorological, and photosynthetic activity indicated the complicated relationships with XCO2. Future carbon research efforts should consider the differences in the magnitude of CO2 variation among biomes and the complex effects of meteorological conditions. Key Points: OCO‐3 detects diurnal variations in XCO2 that follow a near‐sinusoidal patternMeteorological factors affect XCO2 seasonally and nonlinearlyVegetation activity should be observed to understand carbon cycles [ABSTRACT FROM AUTHOR]

Once challenged by the SARS-CoV-2 virus, the human host immune system triggers a dynamic process against infection. We constructed a mathematical model to describe host innate and adaptive immune response to viral challenge. Based on the dynamic properties of viral load and immune response, we classified the resulting dynamics into four modes, reflecting increasing severity of COVID-19 disease. We found the numerical product of immune system's ability to clear the virus and to kill the infected cells, namely immune efficacy, to be predictive of disease severity. We also investigated vaccine-induced protection against SARS-CoV-2 infection. Results suggested that immune efficacy based on memory T cells and neutralizing antibody titers could be used to predict population vaccine protection rates. Finally, we analyzed infection dynamics of SARS-CoV-2 variants within the construct of our mathematical model. Overall, our results provide a systematic framework for understanding the dynamics of host response upon challenge by SARS-CoV-2 infection, and this framework can be used to predict vaccine protection and perform clinical diagnosis. Author summary: Once challenged by the SARS-CoV-2 virus, the host immune system initiates a dynamic process against infection. Countless experimental, clinical, and theoretical studies have been carried out to understand the pathogenesis of SARS-CoV-2 infection, improve treatments or optimize vaccine strategies. Most of the time, people have been focusing on one arm of host immune system during SARS-CoV-2 infection and vaccine protection, despite there are three. A systematic understanding towards the innate, cellular, and humoral immunologic responses remains incomplete. Here, we report a mathematical model that captures the virus-immunity dynamics in both primary infection and vaccine-rendered protection. Mathematical analysis reveals the overall host immune system functions as an integrative dynamic metric combating SARS-CoV-2 infection. The metric reveals the cooperative nature of the immune system, especially between cellular and humoral immune responses. Numerical simulation and data analysis show this metric serves as a strong correlate for disease severity and vaccine protection rates against the original and variant SARS-CoV-2 strains. Our results put forth a systematic framework for understanding the virus-immune interaction during SARS-CoV-2 infection, which could be further deployed for treatment formulation and vaccine optimization. [ABSTRACT FROM AUTHOR]

Mineral dust is a major natural atmospheric aerosol that impacts the Earth's radiation balance. The significant scavenging process of fine particles by the strong wind during the dust episodes provided a relatively clean environment that was favourable for new particle formation (NPF) occurrence. In this study, the NPF occurred following the dust episodes (dust-related NPF), and other cases under clean and polluted conditions were classified based on the long-term particle number size distribution (PNSD) in urban Beijing in spring from 2017 to 2021. It was found that the observed formation (Jobs) and growth rate (GR) of dust-related NPF events were approximately 50 % and 30 % lower than the values of other NPF days, respectively. A typical severe dust storm that originated from Mongolia and swept over northern China on 15–16 March 2021 was analysed, to illustrate how the dust storm influences the NPF event. The maximum hourly mean PM 10 mass concentration reached 8000 µg m -3 during this dust storm. The occurrence of an NPF event after a dust storm was facilitated due to the low condensation sink (∼ 0.005 s -1) caused by the strong dilution process of pre-existing particles. However, a downward trend of particle hygroscopicity was found during dust storm and NPF event as compared with the polluted episode, resulting in an increasing trend of the critical diameter at different supersaturations (ss), where aerosols are activated as cloud condensation nuclei (CCN), although the NPF event occurred when dust faded. The critical diameter was elevated by approximately 6 %–10 % (ss = 0.2 % and 0.7 %) during the dust storm, resulting in a lower CCN activation ratio, especially at low supersaturation. Modifications of the nucleation and growth process, as well as the particle-size distribution and hygroscopicity of the dust particles, provide valuable information that reveals the underlying climate and air quality effects of Asian mineral dust. [ABSTRACT FROM AUTHOR]

Seasonal and diurnal characteristics of the vertical profiles of aerosol properties are essential for detecting the regional transport and the climatic radiative effects of aerosol particles. We have studied the seasonal and diurnal characteristics of the vertical distribution of aerosols in urban Beijing from 2017 to 2021 based on long-term Raman–Mie LiDAR observations. The influence of the vertical distribution of aerosols, the meteorological conditions within the boundary layer, the optical–radiometric properties of aerosols, and their interconnections, were investigated during a heavy haze pollution event in Beijing from 8 to 15 February 2020 using both meteorological and sun photometer data. The aerosol extinction coefficient was highest in summer (0.4 km−1), followed by winter (0.35 km−1), and roughly equal in spring and autumn (0.3 km−1). The aerosol extinction coefficient showed clear daily variations and was different in different seasons as a result of the variation in the height of the boundary layer. During the haze pollution event, the particulate matter mainly consisted of scattered spherical fine particles and the accumulation time of pollutants measured via the AOD440nm and PM2.5 mass concentration was different as a result of the hygroscopic growth of the aerosol particles. This growth increased scattering and led to an increase in the aerosol optical depth. The vertical transport of particulate matter also contributed to the increase in the aerosol optical depth. [ABSTRACT FROM AUTHOR]

The aerosol optical property products of Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) reanalysis dataset have been extensively investigated on a global or regional scale. However, the understanding of MERRA-2 aerosol component products on an extensive temporal and spatial scale is inadequate. Recently, the aerosol component products have been derived from the observations of Polarization and Directionality of the Earth's Reflectances/Polarization and Anisotropy of Reflectance for Atmospheric Science coupled with observations from a Lidar (POLDER/PARASOL). This study presents a quantitative evaluation of the MERRA-2 reanalysis dust and black carbon (BC) column concentration using independent satellite-based aerosol component concentration retrievals. Both GRASP/Component and MERRA-2 reanalysis products can capture well the temporal variation in dust column concentration over the dust emission resource and downwind dust-dominated regions with the correlation coefficient (R) varying from 0.80 to 0.98. MERRA-2 reanalysis dust products present higher column concentration than GRASP/Component dust retrievals with relative differences of about 20~70%, except in the Taklamakan Desert and Bay of Bengal, where the relative differences can be negative. The differences in dust column concentration over the African dust regions are larger than that over the Asian dust regions. Similar temporal variations in BC column concentration are characterized by both GRASP/Component BC retrievals and MERRA-2 BC products with R of about 0.70~0.90, except in the North China Plain region. We should pay more caution with the regional applicability of MERRA-2 component products when large differences and high correlation coefficients are obtained simultaneously. The results are favorable for identifying the behavior of MERRA-2 reanalysis component estimation in a new view and demonstrate a practical application of the satellite-based component retrievals, which could make more contributions to the improvement of model estimation in the near future. [ABSTRACT FROM AUTHOR]

Human-perceived thermal comfort (known as human-perceived temperature) measures the combined effects of multiple meteorological factors (e.g., temperature, humidity, and wind speed) and can be aggravated under the influences of global warming and local human activities. With the most rapid urbanization and the largest population, China is being severely threatened by aggravating human thermal stress. However, the variations of thermal stress in China at a fine scale have not been fully understood. This gap is mainly due to the lack of a high-resolution gridded dataset of human thermal indices. Here, we generated the first high spatial resolution (1 km) dataset of monthly human thermal index collection (HiTIC-Monthly) over China during 2003–2020. In this collection, 12 commonly used thermal indices were generated by the Light Gradient Boosting Machine (LightGBM) learning algorithm from multi-source data, including land surface temperature, topography, land cover, population density, and impervious surface fraction. Their accuracies were comprehensively assessed based on the observations at 2419 weather stations across the mainland of China. The results show that our dataset has desirable accuracies, with the mean R2 , root mean square error, and mean absolute error of 0.996, 0.693 ∘ C, and 0.512 ∘ C, respectively, by averaging the 12 indices. Moreover, the data exhibit high agreements with the observations across spatial and temporal dimensions, demonstrating the broad applicability of our dataset. A comparison with two existing datasets also suggests that our high-resolution dataset can describe a more explicit spatial distribution of the thermal information, showing great potentials in fine-scale (e.g., intra-urban) studies. Further investigation reveals that nearly all thermal indices exhibit increasing trends in most parts of China during 2003–2020. The increase is especially significant in North China, Southwest China, the Tibetan Plateau, and parts of Northwest China, during spring and summer. The HiTIC-Monthly dataset is publicly available from Zenodo at 10.5281/zenodo.6895533 (Zhang et al., 2022a). [ABSTRACT FROM AUTHOR]

In order to understand the mechanisms of poor osseointegration following dental implants in type 2 diabetics, it is important to study the biological properties of alveolar bone osteoblasts isolated from these patients. We collected alveolar bone chips under aseptic conditions and cultured them in vitro using the tissue explants adherent method. The biological properties of these cells were characterized using the following methods: alkaline phosphatase (ALP) chemical staining for cell viability, Alizarin red staining for osteogenic characteristics, MTT test for cell proliferation, enzyme dynamics for ALP contents, radio-immunoassay for bone gla protein (BGP) concentration, and ELISA for the concentration of type I collagen (COL-I) in the supernatant. Furthermore, we detected the adhesion ability of two types of cells from titanium slices using non-specific immunofluorescence staining and cell count. The two cell forms showed no significant difference in morphology under the same culture conditions. However, the alveolar bone osteoblasts received from type 2 diabetic patients had slower growth, lower cell activity and calcium nodule formation than the normal ones. The concentration of ALP, BGP and COL-I was lower in the supernatant of alveolar bone osteoblasts received from type 2 diabetic patients than in that received from normal subjects (P < 0.05). The alveolar bone osteoblasts obtained from type 2 diabetic patients can be successfully cultured in vitro with the same morphology and biological characteristics as those from normal patients, but with slower growth and lower concentration of specific secretion and lower combining ability with titanium than normal ones.

[Display omitted] The Hunga Tonga-Hunga Ha'apai eruption on January 15, 2022 was one of the most explosive volcanic eruptions of the 21st century and has attracted global attention. Here we show that large numbers of the volcanic aerosols from the eruption broke through the tropopause into the lower stratosphere, forming an ash plume with an overshooting top at 25–30 km altitude. In the four days following the eruption, the ash plume moved rapidly westward for nearly 10,000 km under stable stratospheric conditions characterized by strong tropical easterlies, weak meridional winds and weak vertical motion. The intrusion of the ash plume into the stratosphere resulted in a marked increase in atmospheric aerosol loading across northern Australia, with the aerosol optical depth (AOD) observed by satellites and sun-photometers peaking at 1.5 off the coast of northeastern Australia; these effects lasted for nearly three days. The ash plume was characterized by fine-mode particles clustered at a radius of about 0.26 µm, with an observed peak volume of 0.25 µm3 µm−2. The impact of the ash plume associated with the Hunga Tonga eruption on the stratospheric AOD and radiative balance in the tropical southern hemisphere is remarkable, with an observed volcanic-induced perturbation of the regional stratospheric AOD of up to 0.6. This perturbation largely explains an instantaneous bottom (top) of the atmosphere radiative forcing of −105.0 (−65.0) W m−2 on a regional scale. [ABSTRACT FROM AUTHOR]

An assessment and verification of the Langley calibration method of the Sun photometer at Mt Foyeding (MFYD) Observatory in Beijing was performed. We explored whether the Langley plot calibration is practicable for this mountainous site by analyzing the aerosol climatology and carrying out a case study. Then, the aerosol optical depth (AOD) results were verified under the reference of AERONET AOD. The results showed that satisfactory atmospheric conditions are present on winter mornings, characterized by a smaller average AOD (~0.09–0.14) and a lower range ratio (~36.97–63.38%) than in the afternoons and over a whole day. The six days selected as the case study all showed stable atmospheric conditions characterized by daily average triplets of <2% for all wavelengths. The residual sum of squares for V 0 λ at all wavelengths was <0.0002 and the residual standard deviation was <0.2%. A large improvement was found in the linear regression at morning relative to the statistics obtained over the whole day, when the coefficient of determination and residual standard deviation were promoted by 0.22–2.90% and ~2.76–23.32, respectively. The final V 0 λ value was derived from 31 days of observation and the deviations from the reference V 0 λ were about −1.69, −1.29, −0.81, −0.42, −0.34, −0.22, −0.63 and −0.36% at 340, 380, 440, 500, 675, 870, 1020 and 1640 nm, respectively. The regression analysis of the AOD validation showed a perfect AOD performance, with 100% of the retrievals lying within the expected error (0.05 ± 10%) from 380 to 1640 nm and 99.99% for the 340 nm band. Good AOD agreement (correlation coefficients > 0.998) and residual standard deviation values ranging from ~0.006 to 0.011 were observed, with the relative mean bias varying from 0.999 to 1.066. The mean biases were concentrated within ±0.02 for the ultraviolet bands and within ±0.01 for the other bands; therefore, the results of this preliminary assessment and verification indicated that the Langley plots method is suitable for photometer calibration at the MFYD Observatory. [ABSTRACT FROM AUTHOR]

An evaluation of aerosol microphysical, optical and radiative properties measured with a multiwavelength photometer named CW193 was performed in this study. The instrument has a highly integrated design, smart control performance and is composed of three parts (the optical head, robotic drive platform and stents system). Based on synchronous measurements, the CW193 products were validated using reference data from the AERONET CE318 photometer. The results show that the raw digital counts from CW193 agree well with the counts from AERONET (R>0.989), with daily average triplets of around 1.2 % to 3.0 % for the ultraviolet band and less than 2.0 % for the visible and infrared bands. Good aerosol optical depth agreement (R>0.997 , 100 % within expected error) and root mean square error (RMSE) values ranging from 0.006 (for the 870 nm band) to 0.016 (for the 440 nm band) were obtained, with the relative mean bias (RMB) ranging from 0.922 to 1.112 and the aerosol optical depth bias within ±0.04. The maximum deviation of the peak value for fine-mode particles varied from about 8.9 % to 77.6 %, whereas the variation for coarse-mode particles was about 13.1 % to 29.1 %. The deviation variations of the single scattering albedo were approximately 0.1 %–1.8 %, 0.6 %–1.9 %, 0.1 %–2.6 % and 0.8 %–3.5 % for the 440, 675, 870 and 1020 nm bands, respectively. For the aerosol direct radiative forcing, deviations of approximately 4.8 %–12.3 % were obtained at the earth's surface and 5.4 %–15.9 % for the top of the atmosphere. In addition, the water vapor retrievals showed satisfactory accuracy, characterized by a high R value (∼0.997), a small RMSE (∼0.020) and a good expected error distribution (100 % within expected error). The water vapor RMB was about 0.979, and the biases mostly varied within ±0.04 , whereas the mean values were concentrated within ±0.02. [ABSTRACT FROM AUTHOR]