In order to maintain high yields and protect the environment, the replacement of chemical fertilizers with organic ones has received increasing attention in recent years. A 2-year field experiment ...(2015-2016) was carried out to assess the effects of substituting equal amounts of mineral fertilizer with organic manure on the yield, dry matter (DM), and nitrogen (N) uptake of spring maize (Zea mays L.) and on the mineral N (Nmin) distribution in the soil profile. The treatments included chemical fertilizer; different amounts of maize straw, cow manure, and chicken manure; and an unfertilized control (CK). Compared with the chemical fertilizer treatments, equal amounts of substitutions with cow manure or chicken manure increased production, and a 25% nutrient substitution resulted in the best yield increase. Straw return had no effect on maize production, and 100% straw return resulted in reduced production. The N accumulation and DM content both exhibited a slow-fast-slow growth trend throughout the various growth stages, and the average N uptake and DM accumulation in response to the treatments followed the order of chicken manure > cow manure > chemical fertilizer > straw return > CK. The Nmin content in the profile not only increased as the Nmin application rate increased but also showed greater increases at certain depths than at the surface, indicating that excessive N led to leaching. These results suggest that an appropriate proportion of organic substitution not only provides enough nutrients but also improves the soil environment and leads to increased yields. This technique represents a practical method of continuously increasing production and reducing the risk of N leaching.
Since its emergence in December 2019, severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has developed into a global pandemic within a matter of months. While subunit vaccines are one of ...the prominent options for combating coronavirus disease 2019 (COVID‐19), the immunogenicity of spike protein‐based antigens remains unknown. When immunized in mice, the S1 domain induced much higher IgG and IgA antibody levels than the receptor‐binding domain (RBD) and more efficiently neutralized SARS‐CoV‐2 when adjuvanted with alum. It is inferred that a large proportion of these neutralization epitopes are located in the S1 domain but outside the RBD and that some of these are spatial epitopes. This finding indicates that expression systems with posttranslational modification abilities are important to maintain the natural configurations of recombinant spike protein antigens and are critical for effective COVID‐19 vaccines. Further, adjuvants prone to a Th1 response should be considered for S1‐based subunit COVID‐19 vaccines to reduce the potential risk of antibody‐dependent enhancement of infection.
Highlights
Antibodies induced by the S1 domain neutralized SARS‐Cov‐2 more efficiently than those induced by the receptor‐binding domain (RBD). Antibodies induced by the S1 domain produced from HEK293K cells neutralized SARS‐Cov‐2 more efficiently than those induced by the S1 domain produced from E. coli. Both the S1 domain and the RBD induced a highly Th2 response when adjuvanted with alum.
Fluid flow exerts a critical impact on the convection of thermal energy in geological media, whereas heat transport in turn affects fluid properties, including fluid dynamic viscosity and density. ...The interplay of flow and heat transport also affects solute transport. To unravel these complex coupled flow, heat, and solute transport processes, here, we present a theory for the idealized scale‐dependent Poiseuille flow model considering a constant temperature gradient (∇T) along a single fracture, where fluid dynamic viscosity connects with temperature via an exponential function. The idealized scale‐dependent model is validated based on the solutions from direct numerical simulations. We find that the hydraulic conductivity (K) of the Poiseuille flow either increases or decreases with scales depending on ∇T > 0°C/m or ∇T < 0°C/m, respectively. Indeed, the degree of changes in K depends on the magnitude of ∇T and fracture length. The scale‐dependent model provides an alternative explanation for the well‐known scale‐dependent transport problem, for example, the dispersion coefficient increases with travel distance when ∇T > 0°C/m according to the Taylor dispersion theory, because K (or equivalently flux through fractures) scales with fracture length. The proposed theory unravels intertwined interactions between flow and transport processes, which might shed light on understanding many practical geophysical problems, for example, geothermal energy exploration.
•A new barrier is proposed to control seawater intrusion and nitrate contamination.•Effectiveness of seawater intrusion and nitrate accumulation are investigated.•An optimization method is developed ...to design the variable permeability cut-off wall.
Seawater intrusion (SI) is an increased threat to the groundwater resource in coastal regions. The cut-off wall is widely used to arrest the advance of a seawater wedge, but it is likely to cause groundwater contamination in landward aquifers. In order to alleviate the contamination problem, we proposed a new variable-permeability cut-off wall (VPFW) with a semi-permeable section at the bottom of the physical barrier. This study is the first to investigate the spatial distributions and transient behaviors of SI and nitrate pollution at field scale under the joint effects of physical barriers and denitrification. Results show the dissolved oxygen (DO) decreases almost synchronously with the intrusion of SW near the sea boundary, and the denitrification of NO3− and retreat of the dissolved organic carbon (DOC) wedge occurred in the inland aquifer. Notably, the freshwater discharge flux and nitrate discharge flux for the developed VPFW increase by 35% and 20%, respectively, while the enrichment ratio of specific volume of nitrate contamination zone (SVNR) went down by 15% on average compared with the traditional cut-off wall. Four indices were proposed to quantify the impervious barrier: heights (H), relative hydraulic conductivities (K*), and control effectiveness of SI and nitrate pollution. Moreover, we found the control effectiveness for SI and nitrate pollution was continually enhanced with the reduction of K* and increase of H; however, excessive reduction and increase may result in the oppositeimpacts. The optimal K* and H for the VPFW can be determined with the required value of the reduction rate of saltwater wedge length (SWR) and SVNR; but all cut-off wall cases fail to meet the demand. The results show that the VPFW is much more effective in controlling SI and nitrate pollution in comparison with the traditional cut-off wall.
Fluid flow through geologic porous media is represented by Darcy's law and its inertial and nonlinear extension, the Forchheimer equation. These relationships equate the product of the driving ...potential gradient and phenomenological coefficients representing momentum resistance and dissipation to flux. From decades of research, the coefficient of viscous permeability (kv) in Darcy's law is largely predictable, but this is not the case for the coefficient of inertial permeability (ki) in the Forchheimer equation. Synthesizing results from thousands of laboratory and field flow tests and pore‐scale flow model results, we show that ki can be predicted from kv via the equation ki = 1010kv3/2 across 12 and 20 orders of magnitude in kv and ki, respectively. Since it is related with ki, kv is thus sufficient for predicting flow across viscous to inertial regimes for most geologic porous media.
Plain Language Summary
Fluid flow through geologic porous media is dictated by permeability which is the resistance imparted by the medium. Flows in porous media are described by either Darcy's law or its extension for high flow rates, the Forchheimer equation. In both models, permeability represents the dissipation of mechanical energy by inertial losses and by fluid viscosity. Thus, permeability depends on both fluid properties and the configuration of pores. Decades of research has made the permeability in Darcy's law predictable from medium properties such as porosity and grain size, but the additional permeability in the Forchheimer equation has remained almost impossible to predict. This has hindered the application of the Forchheimer equation for many settings where it is potentially more appropriate. Through a broad synthesis of published data and through computational simulations, we were able to relate the permeability in Darcy's law to the permeability in the Forchheimer equation for the diversity of geologic porous media representing varied pore geometries and configurations. Thus, both kinds of permeability are now predictable and linked. This knowledge will help in many geophysical and engineering applications where it is necessary to consider flows at high rates.
Key Points
We analyzed and synthesized viscous and inertial permeability data for different types of geologic porous media
A universal visco‐inertial permeability model is established using the compiled data
The parameter in the universal model is attributed to local surface roughness and void distribution pattern
The extensive utilization of zinc oxide nanoparticles in consumer products and the industry has led to their substantial entry into the soil through air and surface runoff transportation, which ...causes ecotoxicity in agro-ecosystems and detrimental effects on crop production. Nanobubbles (diameter size < 1 µm) have many advantages, such as a high surface area, rapid mass transfer, and long retention time. In this study, wheat seedlings were irrigated with a 500 mg L
zinc oxide nanoparticle solution delivered in the form of nanobubble watering (nanobubble-ZnO-NPs). We found that nanobubble watering improved the growth and nutrient status of wheat exposed to zinc oxide nanoparticles, as evidenced by increased total foliar nitrogen and phosphorus, along with enhanced leaf dry mass per area. This effect can be attributed to nanobubbles disassembling zinc oxide aggregates formed due to soil organic carbon, thereby mitigating nutrient absorption limitations in plants. Furthermore, nanobubbles improved the capability of soil oxygen input, leading to increased root activity and glycolysis efficiency in wheat roots. This work provides valuable insights into the influence of nanobubble watering on soil quality and crop production and offers an innovative approach for agricultural irrigation that enhances the effectiveness and efficiency of water application.
•The microscale and macroscale non-Darcian flow behaviors for rock fracture with fluid slippage were numerically investigated.•Two competing mechanisms impacting the apparent fracture permeability ...due to fluid slippage were revealed.•The slippery fluid flow behavior was tested to be sensitive to the slip length.
Fluid flow in rock fractures is usually theoretically and numerically investigated on the premise of no-slip boundary condition (BC). However, fluid slippage at rock surface is naturally present in some circumstances that might lead to a violation of no-slip BC. How and to what extent slip BC affects non-Darcian fracture flow remains poorly constrained. This study systematically investigated the slippery flow behaviors in rock fractures under sequentially-increasing pressure gradients. Two competing mechanisms impacting the apparent permeability (k) due to fluid slippage were revealed: k was not only enhanced by fluid slippage at fracture walls but also was reduced by the accelerated eddy growth due to enhanced velocity field. The increment in k caused by slip velocity initially dominated over the decrement caused by eddy growth during this competing process, but this dominant situation could reverse given a sufficiently large pressure gradient with fully-developed eddies. Moreover, the slippery fluid flow behavior was tested to be very sensitive to the slip length based on our sensitivity analysis. Therefore, a reasonable estimation of the slip length would be crucial to accurately determine the effects of fluid slippage. This study deepens our understanding of fluid flow in rock fractures when slip BC is present, and might provide theoretical guidance for organic pollution remediation, oil recovery, and geological carbon sequestration in fractured reservoirs.
Understanding daytime (ETD) and nighttime (ETN) evapotranspiration is critical for accurately evaluating terrestrial water and carbon cycles. However, unlike ETD, the factors influencing ETN remain ...poorly understood. Here, long‐term ETD and ETN data from five FLUXNET sites along a climate gradient in Northern Australia were analyzed to compare their responses to environmental drivers at different temporal scales. We found that (a) across the sites, mean annual ETN/ETD (ETN¯/ETD¯) ranged between 5.1% and 11.7%, which was mainly determined by ETD¯ variations. Particularly, vegetation and meteorological variables mostly controlled ETD¯, while ETN¯ was largely related to air temperature and net radiation (Rn) due to lower nighttime atmospheric water demands; (b) At individual sites, ETD and ETN exhibited higher correlations with meteorological and vegetation variables at monthly timescales than at annual timescales. Monthly ETD and ETN were also strongly coupled, especially under drier climatic conditions. At daily timescales, leaf area index and soil water content (SWC) controlled ETD with SWC being more important at drier sites; whereas, SWC was the dominant factor controlling ETN. At half‐hourly timescales, the boosted regression tree method quantitively showed that ETD and ETN were controlled by Rn and SWC, respectively. Overall, the results showed that ETN was less responsive to environmental variables, illustrating that ETD and ETN responded differently to diverse climate regimes and ecosystems at varying temporal scales. These findings provide a critical evaluation for contrasting ETD and ETN interactions in constantly changing environments, which has important implications for ecosystem water balance and land surface processes modeling.
Key Points
Variations in mean annual ETN/ETD ratio (5.1%–11.7%) across the sites were mostly determined by the spatial variability in ETD
ETD and ETN responded differently to climatic drivers from half‐hourly to annual scales, which also depended on ecosystems types
At site levels, leading controls were Rn for half‐hourly ETD, leaf area index (LAI), and soil water content (SWC) for daily to annual ETD, and SWC for half‐hourly to annual ETN
In arid area, the liquid water and water vapour states in soil profiles and fluxes at the upper and bottom interfaces are extremely complex due to heterogeneity of soil textures and the driving ...forces of heat and matrix potential. In this study, we used Hydrus‐1D to simultaneously simulate liquid water, water vapour, and heat transport based on the observed datasets of atmosphere, soil and groundwater at three soil profiles in an arid area of northwest China. Based on the comparison of the observed and simulated results at the three soil profiles, we show that there are diurnal vapour entry and outlet fluxes at the dry surface layer of 30 cm in the summer season. The vapour entry and re‐evaporation account for about 14% of annual precipitation for the heterogeneity soil profile with a mean groundwater depth of 210 cm. Because of limited soil moisture in this arid area, vapour induced re‐evaporation occurs shortly in the early daytime. Moreover, the extent of vapour entry, condensation and re‐evaporation are strongly dependent on soil properties and water table depth. The deeper water table produces the drier soil surface, allowing more vapour entry, condensation and re‐evaporation. Whereas the finer grained soil layers benefit the vapour fixation to produce zero fluxes that substantially inhibit the upward liquid water and vapour fluxes, and thereby reduces soil actual evaporation (AE). The reduced AE correspondingly decreases the capillary effect on phreatic evaporation, given that AE decreases slowly with decline of water table and the large extinct depth of phreatic evaporation for the finer grained soil profiles. The estimated extinct depths are 180 and 200 cm for the soil profiles consisting of silt loam and loamy sand, respectively, much larger than 100 cm of the typical sandy soil profile. Additionally, as water table is comparably higher and lower than the extinct depth, the models neglecting the vapour – heat function could, respectively, overestimate and underestimate soil evaporation.
Vapour transport occurs during moisture loss from unsaturated soils. The effects of the vapour transport depend on atmosphere, soil property and depth to the water table. In this study, we apply Hydrus‐1D for simultaneous simulation of the water–vapour–heat transport in the arid area of northwest China.
Abstract
Background
Oral nucleoside (acid) analogues (NAs) are recommended for patients with acute-on-chronic liver failure (ACLF) associated with hepatitis B virus (HBV-ACLF). The efficacy and ...safety of tenofovir (TDF) and entecavir (ETV) in these patients remain unclear.
Methods
A comprehensive literature search in PubMed, Web of Science, The Cochrane Library, and Embase database was conducted to select studies published before December 2022 on TDF or ETV for HBV-ACLF. The primary outcomes were survival rates at 4, 12, and 48 weeks. Secondary outcomes were virologic and biochemical responses, serum antigen conversion, liver function score, and safety.
Results
Four prospective and one retrospective cohort studies were selected. The overall analysis showed comparable survival rates at 4, 12, and 48 weeks for all patients receiving TDF or ETV (4-week: RR = 1.17, 95% CI: 0.90–1.51,
p
= 0.24; 12-week: RR = 1.00, 95% CI: 0.88–1.13,
p
= 0.94; 48-week: RR = 0.96, 95% CI: 0.58–1.57,
p
= 0.86). Child-Turcotte-Pugh (CTP) score and model for end-stage liver disease (MELD) score at 12 weeks were comparable in both groups but lower than baseline (CTP: SMD = -0.75, 95% CI:-2.81–1.30,
p
= 0.47; MELD: SMD = -1.10, 95% CI:-2.29–0.08,
p
= 0.07). At 48 weeks, estimated glomerular filtration rate (eGFR) levels were found to decrease to different degrees from baseline in both the TDF and ETV groups, and the decrease was greater in the TDF group than in the ETV group. No significant differences were found in biochemical, virologic response, and serum antigen conversion between the two groups during the observation period.
Conclusion
TDF treatment of HBV-ACLF is similar to ETV in improving survival, liver function, and virologic response but the effects on renal function in two groups in the long term remain unclear. More and larger long-term clinical trials are required to confirm these findings.
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