Porcine epidemic diarrhea,a highly contagious enteric infectious disease caused by the porcine epidemic diarrhea virus( PEDV) with symptoms of vomit,diarrhea,loss of appetite of suckling pig,has led to serious economi...Porcine epidemic diarrhea,a highly contagious enteric infectious disease caused by the porcine epidemic diarrhea virus( PEDV) with symptoms of vomit,diarrhea,loss of appetite of suckling pig,has led to serious economic loss to the global swine industry. In this study,a real-time fluorescence reverse transcription loop-mediated isothermal amplification( RT-LAMP) assay was developed to detect PEDV RNA. The real-time fluorescence RT-LAMP assay was performed at62 ℃ for 60 min,using a simple and portable device,the ESE-Quant Tube Scanner. The detection limit of RNA was 2. 9 × 10~6 copies/μl,10 times as sensitive as RT-PCR,and the detection was specific only to PEDV. Application of this method to clinical samples yielded a positivity rate of 93%,which was higher than that of RT-PCR. This technique saves time and is efficient,and is thus expected to be useful for the diagnosis of PEDV infection in the field.展开更多
To understand the effect of regime shift in Caohai Lake in Yunnan-Guizhou Plateau,SW China from submerged macrophyte dominance to phytoplankton dominance on the specification and distribution of phosphorus and on ecol...To understand the effect of regime shift in Caohai Lake in Yunnan-Guizhou Plateau,SW China from submerged macrophyte dominance to phytoplankton dominance on the specification and distribution of phosphorus and on ecological and environmental states,changes in phosphorus specification in the sediments and water were studied.The form,composition,and distribution of phosphorus in sediment were sampled in July 2020(before regime shift)and July 2021(after regime shift)were analyzed.Results reveal that phosphorus content in sediment was lower than that those of Erhai Lake and Dianchi Lake,Yunnan,SW China,on the same plateau,and was lower than those of Taihu Lake,Chaohu Lake,and Poyang Lake in the middle-lower Changjiang(Yangtze)River Plain.Organic phosphorus(Or-P)was the main form(up to 60%),followed by inactive phosphorus(Ina-P),and the active phosphorus(Act-P),the least,which is opposite to those of Taihu Lake and Poyang Lake in the middle-lower Changjiang River Plain in the eastern China.Or-P content was high,indicating a high potential risk of phosphorous release.After the regime shift,the total phosphorus in sediment decreased from 0.87±0.13 to 0.70±0.13 g/kg.The proportion of Or-P and Act-P decreased from 68.23% to 65.32% and from 5.35% to 4.69%,respectively.In contrast,the proportion of Ina-P increased from 26.42% to 29.99%.The Moran’s I index revealed that the heterogeneity of the spatial distributions of the total phosphorus(S-TP)and Act-P in the sediments before regime shift was significant(P<0.1).However,the heterogeneity of the spatial distributions of S-TP and the various forms of phosphorus after regime shift was not significant(P>0.05).The regime shift aggravated the eutrophication of the lake,the trophic level index(TLI)increased from 48.42 to 54.49(P<0.01),and the previously mesotrophic lake became a mildly eutrophic lake.The results of this study revealed the impact of regime shift in the lake from submerged macrophyte dominance to phytoplankton dominance on the composition and spatial distribution of phosphorus in sediments and provided a basis for the restoration of eutrophicated and aquatic ecosystem degraded lakes.展开更多
The phase equilibria and thermodynamic properties of the U-Nb system were investigated through experiments and thermodynamic modeling.In the experiments,a series of samples with different content of Nb were prepared b...The phase equilibria and thermodynamic properties of the U-Nb system were investigated through experiments and thermodynamic modeling.In the experiments,a series of samples with different content of Nb were prepared by arc melting.The Nb content covers the entire composition range of the U-Nb binary system.After solidification,the samples were annealed and then analyzed by X-ray diffraction,scanning electron microscopy,energy dispersive X-ray spectroscopy,differential scanning calorimeter and neutron diffraction.The equilibrium phases,including γ1(U-rich bcc),αU,and γ2(U-depleted bcc),were determined in detail from the experimental characterization.The occurrence of the invariant reaction γ1→αU+γ2 was confirmed,and the reaction temperature and composition were accurately identified.Moreover,the experimental findings clarify the dispute between the Dwight and Terekhov theories regarding the phase region(i.e.,whether the phase region is αU+γ1 or βU+γ2).Furthermore,the U-Nb phase diagram was reassessed by incorporating the present experimental data and previously published reliable experimental data from the literature.A set of self-consistent thermodynamic parameters were developed using CALPHAD(Calculation of phase diagrams),and the calculations reasonably agree with the experimental observations.展开更多
As-cast beryllium-aluminum(Be-Al)alloy exhibits a coarse microstructure with pore defects due to a large solidification interval,greatly limiting its mechanical properties.In this research,the relationship between las...As-cast beryllium-aluminum(Be-Al)alloy exhibits a coarse microstructure with pore defects due to a large solidification interval,greatly limiting its mechanical properties.In this research,the relationship between laser surface remelting process and microstructure and hardness of as-cast Be-Al-Sc-Zr alloy was established.The experimental results demonstrated that a pore-free refined microstructure of remelted layer was obtained by controlling the parameter of effective laser energy input.The microstructure of as-cast Be-Al-Sc-Zr alloy consisted of equiaxed grains with Al phase forming a continuous frame wrapping Be phase,which was significantly refined in the remelted zone(from 25μm to 2μm).The Vickers hardness in the remelted zone(approximately 210 HV)was approximately 3 times that of as-cast Be-Al-Sc-Zr alloy.Analysis of the Vickers hardness and the Be phase size showed a good agreement with a Hall-Petch equation.In addition,transmission electron microscopy(TEM),auger electron spectroscopy(AES)and X-ray diffraction(XRD)analysis evidenced that Sc and Zr elements formed a single blocky phase Be13(Scx,Zr1-x),which was also greatly refined from 8μm to 1.5μm in the remelted zone.The results obtained in this study indicate that the laser surface remelting allowed refining the microstructure and further strengthening the Vickers hardness of Be-Al-Sc-Zr alloy.展开更多
基金Supported by Science and Technology Research Project of Universities in Hebei Province,China(QN2014220)
文摘Porcine epidemic diarrhea,a highly contagious enteric infectious disease caused by the porcine epidemic diarrhea virus( PEDV) with symptoms of vomit,diarrhea,loss of appetite of suckling pig,has led to serious economic loss to the global swine industry. In this study,a real-time fluorescence reverse transcription loop-mediated isothermal amplification( RT-LAMP) assay was developed to detect PEDV RNA. The real-time fluorescence RT-LAMP assay was performed at62 ℃ for 60 min,using a simple and portable device,the ESE-Quant Tube Scanner. The detection limit of RNA was 2. 9 × 10~6 copies/μl,10 times as sensitive as RT-PCR,and the detection was specific only to PEDV. Application of this method to clinical samples yielded a positivity rate of 93%,which was higher than that of RT-PCR. This technique saves time and is efficient,and is thus expected to be useful for the diagnosis of PEDV infection in the field.
基金Supported by the Guizhou Province Science and Technology Plan Project(No.2021470)。
文摘To understand the effect of regime shift in Caohai Lake in Yunnan-Guizhou Plateau,SW China from submerged macrophyte dominance to phytoplankton dominance on the specification and distribution of phosphorus and on ecological and environmental states,changes in phosphorus specification in the sediments and water were studied.The form,composition,and distribution of phosphorus in sediment were sampled in July 2020(before regime shift)and July 2021(after regime shift)were analyzed.Results reveal that phosphorus content in sediment was lower than that those of Erhai Lake and Dianchi Lake,Yunnan,SW China,on the same plateau,and was lower than those of Taihu Lake,Chaohu Lake,and Poyang Lake in the middle-lower Changjiang(Yangtze)River Plain.Organic phosphorus(Or-P)was the main form(up to 60%),followed by inactive phosphorus(Ina-P),and the active phosphorus(Act-P),the least,which is opposite to those of Taihu Lake and Poyang Lake in the middle-lower Changjiang River Plain in the eastern China.Or-P content was high,indicating a high potential risk of phosphorous release.After the regime shift,the total phosphorus in sediment decreased from 0.87±0.13 to 0.70±0.13 g/kg.The proportion of Or-P and Act-P decreased from 68.23% to 65.32% and from 5.35% to 4.69%,respectively.In contrast,the proportion of Ina-P increased from 26.42% to 29.99%.The Moran’s I index revealed that the heterogeneity of the spatial distributions of the total phosphorus(S-TP)and Act-P in the sediments before regime shift was significant(P<0.1).However,the heterogeneity of the spatial distributions of S-TP and the various forms of phosphorus after regime shift was not significant(P>0.05).The regime shift aggravated the eutrophication of the lake,the trophic level index(TLI)increased from 48.42 to 54.49(P<0.01),and the previously mesotrophic lake became a mildly eutrophic lake.The results of this study revealed the impact of regime shift in the lake from submerged macrophyte dominance to phytoplankton dominance on the composition and spatial distribution of phosphorus in sediments and provided a basis for the restoration of eutrophicated and aquatic ecosystem degraded lakes.
基金This work was financially supported by the Science Challenge Project of China(No.TZ2016004)the National Natural Science Foundation of China(No.51701193)the National Key Research and Development Program(No.2016YFB0700404)。
文摘The phase equilibria and thermodynamic properties of the U-Nb system were investigated through experiments and thermodynamic modeling.In the experiments,a series of samples with different content of Nb were prepared by arc melting.The Nb content covers the entire composition range of the U-Nb binary system.After solidification,the samples were annealed and then analyzed by X-ray diffraction,scanning electron microscopy,energy dispersive X-ray spectroscopy,differential scanning calorimeter and neutron diffraction.The equilibrium phases,including γ1(U-rich bcc),αU,and γ2(U-depleted bcc),were determined in detail from the experimental characterization.The occurrence of the invariant reaction γ1→αU+γ2 was confirmed,and the reaction temperature and composition were accurately identified.Moreover,the experimental findings clarify the dispute between the Dwight and Terekhov theories regarding the phase region(i.e.,whether the phase region is αU+γ1 or βU+γ2).Furthermore,the U-Nb phase diagram was reassessed by incorporating the present experimental data and previously published reliable experimental data from the literature.A set of self-consistent thermodynamic parameters were developed using CALPHAD(Calculation of phase diagrams),and the calculations reasonably agree with the experimental observations.
基金co-supported by the National Key Technologies R&D Program of China(No.2016YFB0700404)。
文摘As-cast beryllium-aluminum(Be-Al)alloy exhibits a coarse microstructure with pore defects due to a large solidification interval,greatly limiting its mechanical properties.In this research,the relationship between laser surface remelting process and microstructure and hardness of as-cast Be-Al-Sc-Zr alloy was established.The experimental results demonstrated that a pore-free refined microstructure of remelted layer was obtained by controlling the parameter of effective laser energy input.The microstructure of as-cast Be-Al-Sc-Zr alloy consisted of equiaxed grains with Al phase forming a continuous frame wrapping Be phase,which was significantly refined in the remelted zone(from 25μm to 2μm).The Vickers hardness in the remelted zone(approximately 210 HV)was approximately 3 times that of as-cast Be-Al-Sc-Zr alloy.Analysis of the Vickers hardness and the Be phase size showed a good agreement with a Hall-Petch equation.In addition,transmission electron microscopy(TEM),auger electron spectroscopy(AES)and X-ray diffraction(XRD)analysis evidenced that Sc and Zr elements formed a single blocky phase Be13(Scx,Zr1-x),which was also greatly refined from 8μm to 1.5μm in the remelted zone.The results obtained in this study indicate that the laser surface remelting allowed refining the microstructure and further strengthening the Vickers hardness of Be-Al-Sc-Zr alloy.
