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Two years of data on cloud condensation nuclei (CCN) measured at the Liupan Mountain (LPS) Meteorological Station from August 2020 to November 2021 were analyzed in this study. The results show that the mean annual CCN concentration was 851 cm−3 and that the mean concentration of CCN increases with the supersaturation degree. The curves of the diurnal variation in CCN concentration show one peak and one valley, which correspond to the diurnal variation in the mixed-layer height and valley wind. Regarding seasonal variations, the CCN concentration, as well as the degree of internal mixing, is higher in the spring and winter, while the degree of external mixing is higher in the summer and autumn. The transport of CCN is closely related to the wind transport evolution, and the southeast and southwest sides of the LPS station contribute more to the CCN concentration in the spring and winter due to central heating in the wintertime. Though correlations between CCN concentration and pressure are scarce, the CCN concentration and temperature (or humidity) are positively (or negatively) correlated, especially in the spring. Furthermore, the 48-h backward trajectory analysis indicates that the sources in the northwest direction are a major contributor to the CCN concentration. The pollutants mainly came from the northwest and southwest sides, according to the analysis of potential sources using the PSCF and CWT approach. The study of CCN evolution and contribution area is beneficial for further research on the physical properties of cloud droplets, the influence of mountains on CCN changes and the role of CCN in terrain cloud precipitation, which are significant for the improvement of weather modification techniques. [ABSTRACT FROM AUTHOR]

Bed-parallel fractures are a common feature of organic-rich shales, and are generally interpreted as records of fluid overpressures due to hydrocarbon generation. However, the textural features of such cemented fractures differ widely, and the relationships between these textures and the vein-forming (fracturing and filling) processes—and, critically, their respective roles in accumulation and migration of hydrocarbons—remain uncertain. Here, we compare the physical conditions and opening mode of bed-parallel cemented fractures that show either fibrous texture indicative of antitaxial growth that kept pace with fracture dilation (commonly referred to as "beef"), or blocky texture indicative of unimpeded syntaxial crystallization into an open, fluid-filled space. Specifically, we analyzed formation conditions of bed-parallel fibrous filled fractures in the Shahejie (Eocene) shales, Bohai Bay Basin, east China, and the bed-parallel blocky filled fractures in the Wufeng-Longmaxi (Ordovician-Silurian) shales, Sichuan Basin, southwest China, to evaluate root causes for the different textures of these cements and discuss their roles in self-sourced hydrocarbon accumulation. We report that fluid inclusions in each filling type show distinct and systematic differences in the magnitude of fluid overpressure during different hydrocarbon generation stages of catagenesis. The formation of bed-parallel fibrous filled fractures, including the initial hydraulic fracturing and subsequent crystallization, occurred during the main stage of liquid hydrocarbon generation (i.e., the oil window) when lithostatic fluid pressures were achieved only sporadically and modest overpressures less than lithostatic usually prevailed. The initial bed-parallel fracturing of blocky fillings, in contrast, occurred during the main gas generation stage (i.e., the gas window), and subsequent blocky crystals precipitated after this stage during uplift after the maximum burial. In this case, super-lithostatic overpressures of the CH 4 -saturated fluids persisted essentially continuously and actively expanded the fractures at rates that were not met by the crystallizing cements. Such a model for blocky crystallization in an open horizontal space supported by super-lithostatic fluid pressures in petroliferous systems in sedimentary basins, is analogous to some systems in metamorphic rocks including even orogenic gold deposits, and some magmatic settings, especially related to S-type granites where they form greisens and tin-tungsten deposits by blocky filling of wolframite and quartz, and I-type granitoids where coarse muscovite veins occur for example in the deep roots of porphyry copper systems, as well as numerous pegmatites. Some elements that each of these settings share with the shale-hosted, bed-parallel blocky filled fractures, include that they involve in situ fluid production (by metamorphic devolatilization or magmatic degassing) and fluid escape is stifled by low background permeability such that fluid overpressures can build up, at least periodically, to match or exceed the lithostatic load. As a result of these divergent bed-parallel fracture filling processes, the fibrous textures record conditions of modest permeability that favored accumulation of nascent liquid oil, whereas the blocky fracture cements represent open fractures that contributed to permeability and expulsion of gas. We conclude that the fibrous filled fractures record an opening mode that was beneficial for shale oil enrichment, whereas dilation of blocky filled fractures provides important conduits for hydrocarbon expulsion and release of shale gas. • Bed-parallel fibrous filled fractures formed by modest overpressure in oil window. • Bed-parallel blocky filled fractures formed by higher overpressure in gas window. • Fibrous texture records an opening mode that favors shale oil enrichment. • Dilation of blocky filled fractures provides conduits for the release of shale gas. [ABSTRACT FROM AUTHOR]

A field campaign in Liupan Mountains was carried out by the Weather Modification Center of the China Meteorological Administration to study the impact of terrain on precipitation in Northwest China. The vertical structures and microphysical characteristics of a mixed cloud and precipitation process, which means stratiform clouds with embedded convection, over three topographic positions of the Liupan Mountains, namely, the Longde (LD, located on the windward slope), Liupan (LP, located on the mountain top), and Dawan sites (DW, located on the leeward slope), are compared using measurements from ground-based cloud radar (CR), micro rain radar (MRR), and disdrometer (OTT). The 17 h process is classified into cumulus mixed (1149 min), shallow (528 min), and stratiform (570 min) cloud and precipitation stages. Among them, the vertical structures over the three sites are relatively similar in the third stage, while the differences, mainly in cloud-top heights (CTHs) and rain rates (Rs), are significant in the second stage due to the strong instability. Overall, the characteristics of higher concentrations and smaller diameters of raindrops are found in this study, especially at the LP site. Topographic forcing makes the microphysical and dynamic processes of mountaintop clouds and precipitation more intense. The updrafts are the strongest at the LP, caused by orographic uplifting, and the DW is dominated by the downdrafts due to the topography impact on the dynamic structure. Meanwhile, particle falling velocities (Vts) and downdrafts rapidly increase within 0.6 km near the ground over the LP, forming positive feedback, and the collision–coalescence process is dominant. [ABSTRACT FROM AUTHOR]

The Liupan Mountain (LPM) area is located on the northeast margin of the Qinghai–Tibet Plateau, which is the western part of the second ladder of China's terrain. It is also an intersection area of two air currents, which are caused by the combined action of the Qinghai–Tibet Plateau, the middle and lower levels of the westerly belt and the edge of the monsoon area. LPM is one of the main air water vapour transport pathways in Northwest China as well as a main water conservation area for nearly ten million people. Research on atmospheric precipitable water vapour (PWV) variation characteristics in LPM is beneficial for understanding the mechanisms of orographic precipitation and improving the effects of weather modification. Based on the data from 10 Global Navigation Satellite System Meteorology (GNSS/MET) stations for 6 years and the data of automatic weather stations in the LPM, the temporal and spatial variation characteristics of PWV in the LPM were analysed, and the differences in PWV in the 24 h before and after precipitation were compared in this study. The results showed that the hourly, monthly and seasonal variations in PWV displayed obvious patterns. PWV increased rapidly 10 h ahead of precipitation, while it decreased rapidly within 10 h after precipitation, which was slower than that before precipitation. In terms of spatial distribution, PWV was larger in the south than in the north and larger in the east than in the west. Although the precipitation on the LPM peak was the highest in the whole LPM area, its PWV was always the lowest, indicating that the PWV was obviously affected by the air temperature. This showed that under the same water vapour condition, precipitation was more likely to form in the area with low temperature, and the precipitation was larger, which also provided a train of thought for improving the method of artificial precipitation enhancement by using the condensation catalyst. [ABSTRACT FROM AUTHOR]

Background: In China, nitrogen (N)-deficiency often occurs in Citrus orchards, which is one of the main causes of yield loss and fruit quality decline. Little information is known about the adaptive responses of Citrus carbon (C) and N metabolisms to N-deficiency. Seedlings of 'Xuegan' (Citrus sinensis (L.) Osbeck) were supplied with nutrient solution at an N concentration of 0 (N-deficiency), 5, 10, 15 or 20 mM for 10 weeks. Thereafter, we examined the effects of N supply on the levels of C and N in roots, stems and leaves, and the levels of organic acids, nonstructural carbohydrates, NH4+-N, NO3−-N, total soluble proteins, free amino acids (FAAs) and derivatives (FAADs), and the activities of key enzymes related to N assimilation and organic acid metabolism in roots and leaves. Results: N-deficiency elevated sucrose export from leaves to roots, C and N distributions in roots and C/N ratio in roots, stems and leaves, thus enhancing root dry weight/shoot dry weight ratio and N use efficiency. N-deficient leaves displayed decreased accumulation of starch and total nonstructural carbohydrates (TNC) and increased sucrose/starch ratio as well as a partitioning trend of assimilated C toward to sucrose, but N-deficient roots displayed elevated accumulation of starch and TNC and reduced sucrose/starch ratio as well as a partitioning trend of assimilated C toward to starch. N-deficiency reduced the concentrations of most FAADs and the ratios of total FAADs (TFAADs)/N in leaves and roots. N-deficiency reduced the demand for C skeleton precursors for amino acid biosynthesis, thus lowering TFAADs/C ratio in leaves and roots. N-deficiency increased (decreased) the relative amounts of C-rich (N-rich) FAADs, thus increasing the molar ratio of C/N in TFAADs in leaves and roots. Conclusions: Our findings corroborated our hypothesis that C and N metabolisms displayed adaptive responses to N-deficiency in C. sinensis seedlings, and that some differences existed between roots and leaves in N-deficiency-induced alterations of and C and N metabolisms. [ABSTRACT FROM AUTHOR]

• N-deficient citrus leaves and roots kept high abilities to detoxify ROS and MG. • N-deficiency (ND) affected ROS and MG metabolism more in roots than in leaves. • ND enhanced n distribution in roots and R/S, and delayed root senescence. • ND reduced MDA levels and electrolyte leakage in citrus leaves and roots. Nitrogen-deficiency (ND) usually occurs in some citrus orchard soils in China. The roles of reactive oxygen species (ROS) and methylglyoxal (MG) generation and their detoxification systems in ND tolerance of horticultural woody plants still need to be revealed. For the first time, we examined the effects of ND on ROS and MG generation and their detoxification systems in leaves and roots of Citrus sinensis seedlings. The objectives are to test the hypotheses that N-deficient leaves and roots can keep high abilities to scavenge ROS and MG, thereby protecting them from oxidative damage, and that ND-induced alterations of ROS and MG formation and their detoxification systems in leaves and roots are different. ND augmented superoxide anion production rate and MG concentrations, but it decreased malondialdehyde (MDA) concentrations and electrolyte leakage in leaves and roots. ND increased the activities of most enzymes involved in ROS (ascorbate-glutathione cycle-related enzymes, antioxidant enzymes, and sulfur metabolism-related enzymes) and MG (glyoxalases) detoxification expressed on a protein basis with a few exceptions, and the concentrations of ascorbate, phytochelatins, and total non-protein thiols in leaves and roots. These results suggested that nitrogen-deficient leaves and roots could keep high abilities to detoxify ROS and MG, and protect them from oxidative damage. Generally viewed, ND affected the production and removal of ROS and MG more in roots than in leaves. [ABSTRACT FROM AUTHOR]

Background: The outbreak of coronavirus disease 2019 (COVID-19) has become a global pandemic acute infectious disease, especially with the features of possible asymptomatic carriers and high contagiousness. Currently, it is difficult to quickly identify asymptomatic cases or COVID-19 patients with pneumonia due to limited access to reverse transcription-polymerase chain reaction (RT-PCR) nucleic acid tests and CT scans. Goal: This study aimed to develop a scientific and rigorous clinical diagnostic tool for the rapid prediction of COVID-19 cases based on a COVID-19 clinical case database in China, and to assist doctors to efficiently and precisely diagnose asymptomatic COVID-19 patients and cases who had a false-negative RT-PCR test result. Methods: With online consent, and the approval of the ethics committee of Zhongshan Hospital Fudan University (NCT04275947, B2020-032R) to ensure that patient privacy is protected, clinical information has been uploaded in real-time through the New Coronavirus Intelligent Auto-diagnostic Assistant Application of cloud plus terminal (nCapp) by doctors from different cities (Wuhan, Shanghai, Harbin, Dalian, Wuxi, Qingdao, Rizhao, and Bengbu) during the COVID-19 outbreak in China. By quality control and data anonymization on the platform, a total of 3,249 cases from COVID-19 high-risk groups were collected. The effects of different diagnostic factors were ranked based on the results from a single factor analysis, with 0.05 as the significance level for factor inclusion and 0.1 as the significance level for factor exclusion. Independent variables were selected by the step-forward multivariate logistic regression analysis to obtain the probability model. Findings: We applied the statistical method of a multivariate regression model to the training dataset (1,624 cases) and developed a prediction model for COVID-19 with 9 clinical indicators that are accessible. The area under the receiver operating characteristic (ROC) curve (AUC) for the model was 0.88 (95% CI: 0.86, 0.89) in the training dataset and 0.84 (95% CI: 0.82, 0.86) in the validation dataset (1,625 cases). Discussion: With the assistance of nCapp, a mobile-based diagnostic tool developed from a large database that we collected from COVID-19 high-risk groups in China, frontline doctors can rapidly identify asymptomatic patients and avoid misdiagnoses of cases with false-negative RT-PCR results. [ABSTRACT FROM AUTHOR]

Waste classification is regarded as one of the most important strategies for waste management, and its success depends on the active participation of the public. Based on the theory of planned behavior (TPB) and attitude-behavior-condition (A-B-C) theory, this research investigated the key factors affecting residents' domestic waste classification intention (WCI) and waste classification behavior (WCB), and explored the moderating effects of three external factors including infrastructure (INF), government publicity (GP), and incentive measures (IM) on the intention-behavior relationship. The valid data were collected from 584 residents via conducting a face-to-face interview in Chengdu, a pilot city of waste classification in China, and analyzed by using the structural equation model (SEM). Results showed that residents' WCI and WCB had a significant discrepancy with the average values of 4.07 and 2.81, respectively. Attitude (AT), perceived behavior control (PBC) and classification knowledge (CK) were significantly related to residents' WCI, with AT (β = 0.65, P < 0.001) having the greatest direct impact. Meanwhile, CK and INF had a stronger impact on the WCB than WCI. GP indirectly affected WCB through the intermediary effect of CK. In addition, INF and GP had a positively moderating effect on residents' waste classification intention-behavior relationship and can facilitate the intention-behavior conversion. By contrast, IM failed to promote the conversion of residents' classification intention into behavior, and had no direct significant influence on residents' WCB. Finally, some relevant policy suggestions were put forward for the new pilot cities of waste classification in China. • Key factors affecting residents' WCI and WCB were investigated. • Moderating effects of external factors on intention-behavior relation was explored. • Attitude had the greatest direct influence on residents' WCI. • CK and Infrastructure had a stronger impact on WCB than WCI. • Infrastructure and GP can strengthen the intention-behavior conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recent soils by land reclamation had a fingerprint of sediment in PTE distribution. • Intense and long-term diffuse sources elevated PTE level in old alluvial soils. • Agriculture-derived As and Cd led to bias in GBV calculated from the whole area. • GBV were established on subarea based on PTE source contribution. • Source-based GBV avoid underestimation of PTE contamination from diffuse sources. Intense input of potential toxic elements (PTEs) from diffuse anthropogenic sources to agricultural alluvial soils has caused bias in the geochemical baseline value (GBV) established by current methods. This study intends to assess the extent of bias and establish the GBV for 9 PTEs based on their source contribution on the largest alluvial islands in China, the Chongming Islands. The results of total PTE concentrations in soil samples (n = 120) showed that the islands were influenced by PTEs from various diffuse sources. Source identification methods provided a common conclusion that Ni, Co and Cr were dominated by the Yangtze River sediment input and thus more enriched in "recent" alluvial soils which were generated by large-scale reclamation practices. Positive matrix factorization quantified that pesticides and mineral fertilizer contributed 84.3% of As and 63.6% of Cd, especially in "old" soils, while a large proportion of Cu, Sb, Pb and Zn came from atmospheric deposition. Accumulation of PTEs was enhanced by soil sorption phases including organic matter and clay. Because of this differentiation in source contribution, the GBV of As, Cd, Co and Ni established on "recent" soils are significantly different from those established on data from the whole area. Using this source-based GBVs, the geoaccumulation index method suggested that 37% and 25% of the sampling sites were contaminated by As and Cd, respectively. This study emphasized the importance of considering different sources contribution in GBV determination to avoid underestimation of enrichment of PTEs from intense human diffuse sources. [ABSTRACT FROM AUTHOR]