To synthesize new superheavy elements, the accurate prediction of nuclear masses of superheavy nuclei is essential for calculations of reaction Q values, neutron separation energies and α-decay ...energies, which are important for estimating beam energies, survival probabilities and also for identifications. In this work, we include existing α-decay energies of superheavy nuclei in the fitting procedure of extended Skyrme density functionals as corresponding nuclear masses are not available. Systematic α-decay energies are well reproduced with a standard deviation of 0.24 MeV. The high quality α-decay energies make it feasible for direct identification of new elements and new isotopes. The resulting binding energies in the heaviest region are surprisingly close to the inferences by AME2020. Our work should be useful for guiding experimental synthesis of new elements 119 and 120.
Although the effects of chemical fertilization management on microbial communities in soils have been well studied, few studies have examined such impacts of long-term chemical fertilizations on the ...microbial community in black soils common to northeast China. We applied high-throughput pyrosequencing and quantitative PCR of the 16S rRNA gene to investigate bacterial communities in a long-term fertilizer experiment started in 1980. The following fertilizer treatments were compared with control plots (no fertilizer): N1 (low nitrogen fertilizer), N2 (high nitrogen fertilizer), N1P1 (low nitrogen plus low phosphorus fertilizers) and N2P2 (high nitrogen plus high phosphorus fertilizers). All fertilization treatments resulted in decreases in soil pH and increases in wheat yield and concentrations of total nitrogen, organic matter and KCl-extractable NO3− and NH4+. Fertilization also led to a significant decrease in total 16S rRNA gene abundance and bacterial diversity. The phyla Proteobacteria, Acidobacteria and Actinobacteria dominated in all fertilized treatments. There was an increase in relative abundance of Actinobacteria, Proteobacteria, TM7 and Verrucomicrobia across all fertilized treatments compared to unfertilized controls, whereas phyla Acidobacteria and Nitrospirae decreased. The bacterial communities in unfertilized controls and lower-mineral fertilizers (i.e. N1 and N1P1) were predominantly composed of Acidobacteria, Actinobacteria and Proteobacteria, and separated from the communities where more concentrated fertilizer regimes were used (i.e. N2 and N2P2) based on principal coordinates analysis. Soil pH and NO3− concentration appeared to be the most important factors in shaping bacterial communities. Our findings suggested that long-term inorganic fertilizer regimes reduced the biodiversity and abundance of bacteria. The influence of more concentrated fertilizer treatments was greater than that of lower concentrations.
•We assessed effects of long-term inorganic fertilization on the bacterial and archaeal community structure.•pH and NO3− concentration played important roles in shaping the community structures.•Bacterial and archaeal community diversity and richness appeared to be affected by inorganic fertilization.•Bacterial and archaeal community composition differed between soils treated with higher and lower concentrations of fertilizer.
Black soil is one of the main soil types in northeast China, and plays an important role in Chinese crop production. However, nitrogen inputs over 50 years have led to reduced black soil fertility. ...It is unclear how N affects the fungal community in this soil type, so a long-term fertilizer experiment was begun in 1980 and we applied 454 pyrosequencing and quantitative PCR to targeted fungal ITS genes. There were five treatments: control (no fertilizer), N1 (low nitrogen fertilizer), N2 (high nitrogen fertilizer), N1P1 (low nitrogen plus low phosphorus fertilizers) and N2P2 (high nitrogen plus high phosphorus fertilizers). Soil nutrient concentrations (Total N, Avail N, NO3−, NH4+, etc.) and ITS gene copy numbers increased, whereas soil pH and fungal diversity decreased in all the fertilized treatments. Relationships between soil parameters and fungal communities were evaluated. Dothideomycetes, Eurotiomycetes, Leotiomycetes, Sordariomycetes, and Agaricomycetes were the most abundant classes in all soils. Principal coordinates analysis showed that the fungal communities in the control and lower-fertilizer treatments clustered closely and were separated from communities where more concentrated fertilizers were used. Fungal diversity and ITS gene copy number were dependent on soil pH. Our findings suggested that long-term nitrogen and phosphorous fertilizer regimes reduced fungal biodiversity and changed community composition. The influence of the more concentrated fertilizer treatments was greater than the lower concentrations.
•We assessed effects of long-term nitrogen fertilization on the fungal community structure.•Fungal diversity and the number of ITS gene were affected by nitrogen fertilization.•Fungal community composition differed between soils treated with higher and lower concentrations of nitrogen fertilizer.•The influence of the more concentrated fertilizer treatments was greater than the lower concentrations.
Monopile foundations are the most common foundation type of offshore wind turbines. In the ocean environment, in addition to threats related to scour of the foundation, offshore monopiles of wind ...turbines also are subjected to lateral vibrations induced by waves and winds. Over the past decades, the scour process induced by flow and pile-soil interactions has been independently investigated by researchers from the fields of hydraulic/coastal engineering and soil mechanics, respectively. Very few studies can be found in the published literature on lateral vibration effects on scour at monopile foundations. The objective of this experimental study is to improve understanding of the mechanics of current-induced scour at monopiles subjected to lateral vibrations with a non-cohesive bed. When compared to a non-vibrating monopile, the results show that scouring around its vibrating counterpart is comparatively faster during the first few hours of the test. This is primarily due to soil densification and the subsidence process induced by monopile-seabed interactions. Increasing both the frequency and amplitude of the monopile vibration would decrease the equilibrium scour depths and scour hole slopes. The reduction of equilibrium scour depth likely is due to the effect of sediment ratcheting motions on the surface of the scour hole. An empirical dimensionless equation is proposed to estimate equilibrium scour depth at monopiles subjected to lateral vibrations.
•New experimental results of temporal evolution of scour depth and final scour geometry at vibrating monopiles.•New conceptual model of scour mechanism around monopile foundations subjected to lateral vibrations.•New relationship between scour reduction and vibration properties of a monopile.
Fertilizer-induced changes in soil nutrients regulate nitrogen (N) fixation in the terrestrial biosphere, but the influences of N and phosphorus (P) fertilization on the diazotroph communities in ...successive crop seasons were unclear. In this study, we assessed the effects of N and P (high vs. low doses) on the abundance and structure of N
-fixation communities after wheat and soybean harvest in a long-term (34 and 35 years) fertilization experiment. In both seasons, long-term N addition significantly decreased the abundance of nifH genes and 16S rDNA; in addition, high doses of N and P fertilizer decreased the richness of diazotrophs, whereas low doses did not. The proportion of the dominant genus, Bradyrhizobium, in the soybean season (86.0%) was higher than that in the wheat season (47.9%). Fertilization decreased diazotroph diversity and the relative abundance of Bradyrhizobium in the wheat season, but had insignificant effects in the soybean season. The addition of N, but not P, significantly changed the communities of both diazotrophs (at the genus level) and rhizobia (at the species level) in the two seasons. Soil pH was positively associated with nifH abundance and diazotrophic richness; soil NO
content was negatively correlated with diazotrophic richness and positively correlated with diversity. Soil pH and NO
content were the two main drivers shaping the soil diazotrophic community. Overall, long-term inorganic N had a greater influence than P on both diazotrophic abundance and community composition, and diazotrophic diversity was more clearly affected by fertilization in the wheat season than in the soybean season.
•Bacterial community in bulk and rhizosphere were altered by 36 years fertilization.•Bacterial abundance and diversity differed between bulk and rhizospheric soils.•Soil nutrients played different ...roles in bulk and rhizosphere bacterial community.•pH was an important factor in shaping the community in bulk and rhizospheric soils.
The rhizosphere is a dynamic interface in which interactions among a myriad of microorganisms affect plants growth and tolerance to biotic and abiotic stress. Although rhizosphere effects on soil microbial communities have been widely investigated, few studies have evaluated such impacts of long-term fertilization on rhizosphere microbial communities in black soils common to northeast China. Here, we applied quantitative real-time polymerase chain reaction and high-throughput pyrosequencing to characterize rhizosphere and bulk soil bacterial communities in a long-term (36-year) fertilizer experiment. Soils were subjected to six treatments: CK (no fertilizer), N1 (150 kg urea ha−1 y−1), N2 (300 kg urea ha−1 y−1), M (18,600 kg horse manure ha−1 y−1), NPK (150 kg urea plus 33 kg P plus 62 kg K ha−1 y−1), and MNPK (M plus NPK). Inorganic fertilizer, especially N, decreased the 16S rRNA gene copy numbers and bacterial diversity in the rhizosphere and bulk soil, while manure fertilizer increased these values. Moreover, 16S rRNA gene copy numbers were higher and bacterial diversity was lower in the rhizosphere than the bulk soil, indicating that the maize rhizosphere had significant effects on bacterial diversity. The bacterial communities were predominantly composed of Proteobacteria and Acidobacteria in both the rhizosphere and bulk soil, but the rhizosphere and bulk soil communities were distinguished by principal coordinates analysis. Soil pH correlated with bacterial community composition and diversity in both rhizosphere and bulk soil. However, bacterial community composition in rhizosphere was more correlated with soil nutrient concentrations than in bulk soil under long-term fertilization. A redundancy analysis also indicated that soil pH, organic matter and available phosphorus concentrations were the most important factors in shaping bacterial communities in the maize rhizosphere. Our results revealed that long-term fertilization with increasing nutrients availability increased bacterial abundance, decreased biodiversity and changed bacterial composition in the rhizosphere.
•35 years of inorganic fertilizer and manure amendment alter the soil bacterial and archaeal community.•pH and NO3− concentration played important roles in shaping the community structures.•Inorganic ...fertilizers decrease soil bacterial and archaeal diversity.•The incorporation of inorganic fertilizer and manure increase soil bacterial and archaeal diversity.
Black soil is common in northeast China and plays an important role in Chinese crop production. However, in the past three decades, inappropriate use of fertilizer has caused a sequence of agroecological issues. The objective of this research was to evaluate the effect of long-term fertilizer on the microbial communities in black soil. The soil was subjected to four fertilization regimes: without fertilizer (CK); manure (M); nitrogen, phosphorus and potassium inorganic fertilizer (NPK); and inorganic fertilizers with manure (MNPK). The soil pH was decreased by inorganic fertilizers and increased by manure. Quantitative PCR analysis of microbial community size and Illumina platform-based analysis of the V4 16S rRNA gene region were performed to characterize soil microbial abundance and to compare community structure and diversity. Microbial community size was enhanced by the incorporation of inorganic fertilizer and manure. Microbial diversity was decreased by inorganic fertilizer and increased by the incorporation of inorganic fertilizer and manure. The predominate phyla in all samples were Proteobacteria (29.39–33.48%), Acidobacteria (13.14–16.25%) and Actinobacteria (9.32–10.77%). The relative abundance of different classes significantly differed among the different treatments, especially MNPK and NPK. Acidobacteria and Deltaproteobacteria were relatively stable in organic fertilizer treated soil. Gammaproteobacteria, Alphaproteobacteria and Betaproteobacteria were sensitive to all the fertilization regimes. Comparatively, Spartobacteria was stable in response to fertilization practices. Principal coordinate analysis indicated that microbial communities were primarily clustered into three groups: CK and M were clustered together; MNPK was improved by manure and separated from NPK. Shannon and Simpson indexes were significantly correlated with soil pH and the concentrations of available phosphorus and total phosphorus. Redundancy analysis indicates that microbial communities were closely positively correlated with soil nitrate nitrogen concentration (P=0.002) and pH (P=0.002). These results indicate that inorganic fertilizer plus manure increased microbial size and diversity and changed microbial composition.
Since local scour at bridge piers in rivers and estuaries is a major cause of bridge failure, estimation of the maximum local scour depth is of great importance to hydraulic and coastal engineers. ...Although numerous studies that focus on scour-depth prediction have been done and published, understanding of the flow and turbulence characteristics of the horseshoe vortex that drives the scour mechanism in a developing scour hole still is immature. This study aims to quantify the detailed turbulent flow field in a developing clear-water scour hole at a circular pier using Particle Image Velocimetry (PIV). The distributions of velocity fields, turbulence intensities, and Reynolds shear stresses of the horseshoe vortex that form in front of the pier at different scour stages (t = 0, 0.5, 1, 12, 24, and 48 h) are presented in this paper. During scour development, the horseshoe vortex system was found to evolve from one initially small vortex to three vortices. The strength and size of the main vortex are found to increase with increasing scour depth. The regions of both the maximum turbulence intensity and Reynolds shear stress are found to form at a location upstream of the main vortex, where the large turbulent eddies have the highest possibility of occurrence. Results from this study not only provide new insight into the complex flow-sediment interaction at bridge piers, but also provide valuable experimental databases for advanced numerical simulations.
Long-term use of inorganic nitrogen (N) fertilization has greatly influenced the bacterial community in black soil of northeast China. It is unclear how N affects the bacterial community in two ...successive crop seasons in the same field for this soil type. We sampled soils from a long-term fertilizer experimental field in Harbin city with three N gradients. We applied sequencing and quantitative PCR targeting at the 16S rRNA gene to examine shifts in bacterial communities and test consistent shifts and driving-factors bacterial responses to elevated N additions. N addition decreased soil pH and bacterial 16S rDNA copy numbers, and increased soil N and crop yield. N addition consistently decreased bacterial diversity and altered bacterial community composition, by increasing the relative abundance of Proteobacteria, and decreasing that of Acidobacteria and Nitrospirae in both seasons. Consistent changes in the abundant classes and genera, and the structure of the bacterial communities across both seasons were observed. Our results suggest that increases in N inputs had consistent effects on the richness, diversity and composition of soil bacterial communities across the crop seasons in two continuous years, and the N addition and the subsequent edaphic changes were important factors in shaping bacterial community structures.
AbstractScouring downstream of submerged weirs is a common problem resulting from the interaction of the three-dimensional turbulent flow field around the structures and the mobile channel bed. This ...paper presents the distributions of flow patterns, bed shear stresses, and turbulence structures in the approach flow and the scour hole downstream of a submerged weir. The experiments were conducted under the clear-water scour condition for an equilibrium scour hole. The experimental results show that the flow structures are considerably changed by the presence of the structure. A large recirculation zone and a flow reattachment region are formed downstream of the submerged weir. Strongly paired cellular secondary flows are observed in the scour hole. The turbulence structures ahead of the recirculation zone govern the dimensions of the scour hole.
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