In order to understand the degradation of different residual pesticides of white clover silage and their influence on silage quality, three commonly used orchard pesticides with different ...concentrations were added to the white clover and fermented for 90 days. The results showed that the degradation rate of cypermethrin and its toxic degradation product 3-phenoxybenzoic acid (3-PBA) was the highest after silage, at different concentrations, both were 100%. The degradation rate of Tebuconazole and chloropyridine was 72.47–80.27% and 47.76–64.82%, of which 3,5,6-trichloro-2-pyridinol (TCP) content, poisonous toxic degradation product, increased 0.0525–0.253 mg·kg−1. The residues of beta-cypermethrin and tebuconazole had reached safety standards after silage. As compared with the control, the contents of lactic acid, acetic acid, and propionic acid increased in the treated samples. The higher concentrations of three pesticides all significantly reduced the lactic acid content of silage (p<0.05). Pesticides had different effects on the nutritional components of white clover silage. Conclusively, silage is a potential way to expand the utilization of covering plants in orchards.
Wind erosion happens frequently in winter and spring, when vegetation is bare and the surface soil is prone to erosion. Therefore, the erosion resistance provided by litter is important. To ...investigate the soil erosion-reducing efficiency of different types of litter, litter-covered sites of Populus simonii (LPS), Caragana korshinskii (LCK) and Bothriochloa ischaemum (LBI) were studied, respectively, and bare sandy land (BSL) was taken as a control. Results showed that litter cover increased the aerodynamic roughness by 44.9%–107.1% and the friction velocity by 11.5%–52.0%. Under the conditions of fixed coverage, changing wind speed and conditions of fixed wind speed, changing coverage, the average soil erosion-reducing efficiency both showed the highest in LBI, followed by LCK and LPS. According to the trend analysis, the critical coverage of litter of Populus simonii (PS), Caragana korshinskii (CK) and Bothriochloa ischaemum (BI) to reduce the soil erosion were 8.7%, 8.2% and 9.1%, respectively. We concluded that the soil erosion-reducing efficiency varied due to the shape of litter, and the difference was significant at high wind speed (10 m s−1 and 12 m s−1). Besides, not all litter cover was effective in reducing erosion, and the critical coverage was a crucial factor that cannot be ignored.
•When the coverage of litter was fixed and the wind speed was adjusted, the erosion reduction efficiencies were 49.1% ~ 96.6%.•When the wind speed was fixed and the coverage of litter was changed, the wind erosion reduction efficiencies were –10.2% ~ 80.6%.•According to the trend, the critical coverage of litter to reduce soil erosion were 8.2% ~ 9.1%.•The erosion reduction effect caused by the difference in the shape of litter was particularly obvious at high wind speeds.•The wind erosion reduction efficiency showed that litter-covered sites of BI > CK > PS.
In order to understand the degradation of different residual pesticides of white clover silage and their influence on silage quality, three commonly used orchard pesticides with different ...concentrations were added to the white clover and fermented for 90 days. The results showed that the degradation rate of cypermethrin and its toxic degradation product 3-phenoxybenzoic acid (3-PBA) was the highest after silage, at different concentrations, both were 100%. The degradation rate of Tebuconazole and chloropyridine was 72.47–80.27% and 47.76–64.82%, of which 3,5,6-trichloro-2-pyridinol (TCP) content, poisonous toxic degradation product, increased 0.0525–0.253 mg·kg−1. The residues of beta-cypermethrin and tebuconazole had reached safety standards after silage. As compared with the control, the contents of lactic acid, acetic acid, and propionic acid increased in the treated samples. The higher concentrations of three pesticides all significantly reduced the lactic acid content of silage (p<0.05). Pesticides had different effects on the nutritional components of white clover silage. Conclusively, silage is a potential way to expand the utilization of covering plants in orchards.
Coronavirus disease 2019 (COVID-19) is caused by SARS-CoV-2 infection and was first reported in central China in December 2019. Extensive molecular surveillance in Guangdong, China’s most populous ...province, during early 2020 resulted in 1,388 reported RNA-positive cases from 1.6 million tests. In order to understand the molecular epidemiology and genetic diversity of SARS-CoV-2 in China, we generated 53 genomes from infected individuals in Guangdong using a combination of metagenomic sequencing and tiling amplicon approaches. Combined epidemiological and phylogenetic analyses indicate multiple independent introductions to Guangdong, although phylogenetic clustering is uncertain because of low virus genetic variation early in the pandemic. Our results illustrate how the timing, size, and duration of putative local transmission chains were constrained by national travel restrictions and by the province’s large-scale intensive surveillance and intervention measures. Despite these successes, COVID-19 surveillance in Guangdong is still required, because the number of cases imported from other countries has increased.
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•1.6 million tests identified 1,388 SARS-CoV-2 infections in Guangdong by 19 March•Virus genomes can be recovered using a variety of sequencing approaches•Analyses reveal multiple viral importations with limited local transmission•Effective control measures helped reduce and eliminate chains of viral transmission
Genomic and epidemiological analyses provide insights into how COVID-19 was contained in China’s most populous province using a combination of surveillance and travel restriction measures.
The interfacial corrosion behavior between LBE adding O atoms and Fe substrate surface containing alloy elements (Cr, Ni, Al, Si) has been studied by first-principles molecular dynamics simulations. ...Theoretical calculations show that the O atoms in liquid LBE could form the protective oxide layer with the alloy elements (Cr, Al, Si) on the Fe substrate surface at the iron-liquid LBE interface, in which slows down the corrosion process. The estimated mean effective potential energy path suggests that breaking the OSi bond requires the highest energy barrier of 0.61 eV among the doped elements. Besides, the diffusion coefficient shows that Si atom has the lowest value of 0.277 × 10−5 cm2/s, which indicated that adding doped-Si atoms can effectively slow down the corrosion process of the steel. In addition, the diffusion coefficient of Pb, Bi and O atoms in this work is much lower compared with the previous work, indicating that the oxide layer formed at the iron-liquid LBE interface can effectively improve the corrosion resistance of the steel. In a word, this work is instructive for a deeper understanding of corrosion mechanism and provides valuable information for the performance evaluation and material design of the steel under reactor conditions.
When liquid LBE is in contact with the Fe substrate in a high temperature environment(773 K), the O atoms in liquid LBE will bond with Cr, Al or Si atoms and then form tetrahedral-like protective oxide layer, while the Ni atoms are inclined to dissolve in liquid LBE first. Above all, adding doped Al/Si atoms can improve the corrosion resistance of the steel. Display omitted
•CP2K software was employed to study the interfacial corrosion behavior between LBE and steel.•O atoms are inclined to form tetrahedral-like O-complexes at iron-liquid LBE interface, in which slows down the corrosion process.•The diffusion coefficient of Pb, Bi and O atoms are much lower than previous work, indicating the O-complexes can effectively improve the corrosion-resistance of the steel.
The corrosion of lead-bismuth on steel has received much attention in ADSs. Unfortunately, the current studies are mostly based on the ideal Fe surface, but in reality, the surface of the steel is ...rough. In this work, the rough surface is built. By performing first-principles calculations, using adsorption and escape energies to evaluate the mechanism of dissolution corrosion on rough surfaces. The smaller adsorption energy indicates more stable adsorption properties on the rough surface for adatoms. According to the process of dissolution corrosion, the surface is more likely to be corroded. The energetics results mean that bismuth atoms are more stable on the rough surface. Combined with escape energy, rough surfaces are more susceptible to corrosion than ideal surfaces. This is further demonstrated by calculating the charge density difference of surface. Based on previous research, three alloying elements, Al, Si, and Mo, which have the best corrosion resistance, were selected for further discussion. Finally, adsorption energy is utilized to evaluate how alloy atoms affect surface dissolution corrosion. The results show that when there are four alloy atoms on the surface, the probability of Pb or Bi atom corrosion on the surface is the least.
Because of the innovative concepts for creating the thorium fuel cycle as an alternative nuclear energy source, thorium and its compounds have attracted a lot of attention. It is essential to study ...the physical properties that are necessary for the basic understanding and practical application of these materials. Thorium monoxide has already drawn researchers' attention as a metal oxide. Under different pressure conditions, the crystal structures, electronic band structures, phonon dispersions, mechanical properties, and thermodynamic properties of ThO have been determined using a particle swarm optimization structure prediction method in conjunction with first-principles calculations. Previous experiments agree with our results for the lattice constants of the phase of Fm3¯m. Moreover, a novel structure of R-3m is predicted to be thermally stable at a pressure of roughly 22 GPa. The phase is then also mechanically and dynamically stable, according to the findings of our computed elastic constants and phonon dispersion. The phase change from Fm3¯m to R-3m has not, however, been associated with any electronic transitions, and as both phases are mental, they may have excellent thermal conductivity. We further calculated the results of the Helmholtz free energy, entropy, specific heat, internal energy, bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and Debye temperature based on the stable dynamics and mechanical properties, which reveal that they all could be good fuel. The results provide key insights into understanding the structural and electronic behaviors of ThO under the condition of external pressure.
When the second phase is precipitated from the iron surface, the iron surface and the second phase precipitate constitute the galvanic cell. The occurrence of REDOX reaction is accompanied by the ...process of surface electrochemical corrosion, resulting in the continuous dissolution of the anode material. Above all, the existence of Al/Si atoms can reduce the open circuit voltage between anode and cathode materials to improve the corrosion resistance of the steel.
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The electrochemical corrosion on the face-centred cubic Fe (111) surface is studied on the basis of first-principles calculations when the lead–bismuth eutectic and the second phase precipitates coexist. The precipitates on the iron surface have a great effect on the surface properties, which can form the micro galvanic cell to cause electrochemical corrosion of the anode under corrosive conditions. The electrochemical corrosion was assessed by calculating the electrode potential of the half electrode (Fe surface). In addition, the effect of various alloy combinations on corrosion resistance was studied and a theoretical scheme for experimental design was proposed. Finally, in order to determine the electrochemical corrosion mechanism, the energetic, microstructural and electronic properties were analysed. The results show that the influence of Bi atoms on the surface electrode potential is greater than that of Pb atoms, and the existence of Al and Si atoms slows down the electrochemical corrosion of the anode to a great extent.
Background and aims
Cadmium (Cd) is a ubiquitous environmental pollutant, and rice (
Oryza sativa
L.) is the main staple food in China. Water regimes are promising, controllable, and ...environment-friendly agricultural measures for remediation Cd contaminated soil. The optimum water regime for ensuring high rice yield with low Cd contents in brown rice was investigated.
Methods
A pot experiment was conducted to study the effects of Cd migration and accumulation from paddy soil to rice plants under four water regimes with three growth stages of two rice cultivars, ‘Xiangwanxian 12’ (X12) and ‘Weiyou 46’ (W46) grown in a polluted soil with 5 mg kg
−1
of Cd. The relationship between Cd accumulation amounts in rice plant and soil Eh was also investigated. The four regimes were moisture throughout growth (M), moisture before the filling stage and flooding after filling (M-F), flooding before filling and moisture after filling (F-M), and continual flooding (F).
Results
Water regimes effectively reduced Cd accumulation in rice at the three growth stages, whereas the filling stage was suggested to be as the key stage for interventions to prevent Cd transport and accumulation. Compared with M, the M-F, F-M, and F regimes significantly reduced Cd contents of rice tissues (root, stem, husk, and brown rice) at the maturity stage. Under the M, F-M, M-F, and F regimes, Cd contents were 2.17, 2.10, 0.21, 0.06 mg kg
−1
in X12 brown rice and 3.27, 0.47, 0.19, 0.10 mg kg
−1
in W46 brown rice, respectively. Importantly, Cd contents of brown rice of X12 (0.06 mg kg
−1
under regime F) and W46 (0.19 mg kg
−1
under regime M-F and 0.10 mg kg
−1
under regime F) did not exceed China’s food safety standard of 0.20 mg kg
−1
(GB 2762–2017). Moreover, there were significant positive exponential relationships between soil Eh and Cd accumulation amounts in belowground and aboveground parts of rice.
Conclusions
The M-F regime (W46) and F regime (X12) could ensure high rice yield with low Cd contents in brown rice and could be recommended as the irrigation management in rice production. Simultaneously, keeping soil Eh under 50 mV is also necessary after the rice filling stage.
Summary
Adenine base editors (ABEs) have been exploited to introduce targeted adenine (A) to guanine (G) base conversions in various plant genomes, including rice, wheat and Arabidopsis. However, the ...ABEs reported thus far are all quite inefficient at many target sites in rice, which hampers their applications in plant genome engineering and crop breeding. Here, we show that unlike in the mammalian system, a simplified base editor ABE‐P1S (Adenine Base Editor‐Plant version 1 Simplified) containing the ecTadA*7.10‐nSpCas9 (D10A) fusion has much higher editing efficiency in rice compared to the widely used ABE‐P1 consisting of the ecTadA‐ecTadA*7.10‐nSpCas9 (D10A) fusion. We found that the protein expression level of ABE‐P1S is higher than that of ABE‐P1 in rice calli and protoplasts, which may explain the higher editing efficiency of ABE‐P1S in different rice varieties. Moreover, we demonstrate that the ecTadA*7.10‐nCas9 fusion can be used to improve the editing efficiency of other ABEs containing SaCas9 or the engineered SaKKH‐Cas9 variant. These more efficient ABEs will help advance trait improvements in rice and other crops.
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