Purple-leaf tea plants,as anthocyanin-rich cultivars,are valuable materials for manufacturing teas with unique colors or flavors.In this study,a new purple-leaf cultivar“Zixin”(“ZX”)was examined,and its biochemica...Purple-leaf tea plants,as anthocyanin-rich cultivars,are valuable materials for manufacturing teas with unique colors or flavors.In this study,a new purple-leaf cultivar“Zixin”(“ZX”)was examined,and its biochemical variation and mechanism of leaf color change were elucidated.The metabolomes of leaves of“ZX”at completely purple,intermediately purple,and completely green stages were analyzed using ultra-performance liquid chromatography quadrupole time of flight mass spectrometry(UPLC-QTOF-MS).Metabolites in the flavonoid biosynthetic pathway remained at high levels in purple leaves,whereas intermediates of porphyrin and chlorophyll metabolism and carotenoid biosynthesis exhibited high levels in green leaves.In addition,fatty acid metabolism was more active in purple leaves,and steroids maintained higher levels in green leaves.Saponin,alcohol,organic acid,and terpenoid-related metabolites also changed significantly during the leaf color change process.Furthermore,the substance changes between“ZX”and“Zijuan”(a thoroughly studied purple-leaf cultivar)were also compared.The leaf color change in“Zijuan”was mainly caused by a decrease in flavonoids/anthocyanins.However,a decrease in flavonoids/anthocyanins,an enhancement of porphyrin,chlorophyll metabolism,carotenoid biosynthesis,and steroids,and a decrease in fatty acids synergistically caused the leaf color change in“ZX”.These findings will facilitate comprehensive research on the regulatory mechanisms of leaf color change in purple-leaf tea cultivars.展开更多
The spatial resolution of general circulation models (GCMs) is too coarse to represent regional climate variations at the regional, basin, and local scales required for many environmental modeling and impact assessm...The spatial resolution of general circulation models (GCMs) is too coarse to represent regional climate variations at the regional, basin, and local scales required for many environmental modeling and impact assessments. Weather research and forecasting model (WRF) is a nextgeneration, fully compressible, Euler non-hydrostatic mesoscale forecast model with a runtime hydrostatic option. This model is useful for downscaling weather and climate at the scales from one kilometer to thousands of kilometers, and is useful for deriving meteorological parameters required for hydrological simulation too. The objective of this paper is to validate WRF simulating 5 km/ 1 h air temperatures by daily observed data of China Meteorological Administration (CMA) stations, and by hourly in-situ data of the Watershed Allied Telemetry Experimental Research Project. The daily validation shows that the WRF simulation has good agreement with the observed data; the R2 between the WRF simulation and each station is more than 0.93; the absolute of meanbias error (MBE) for each station is less than 2℃; and the MBEs of Ejina, Mazongshan and Alxa stations are near zero, with R2 is more than 0.98, which can be taken as an unbiased estimation. The hourly validation shows that the WRF simulation can capture the basic trend of observed data, the MBE of each site is approximately 2℃, the R2 of each site is more than 0.80, with the highest at 0.95, and the computed and observed surface air temperature series show a significantly similar trend.展开更多
The effects of thermomechanical treatment on the properties and microstructure of Cu-Cr-Zr alloy and Cu-Cr-Zr-Ag alloy were investigated. Ag addition improves the mechanical properties of the alloy through solid solut...The effects of thermomechanical treatment on the properties and microstructure of Cu-Cr-Zr alloy and Cu-Cr-Zr-Ag alloy were investigated. Ag addition improves the mechanical properties of the alloy through solid solution strengthening and brings a little effect on the electrical conductivity of the alloy. A new Cu-Cr-Zr-Ag alloy was developed, which has an excellent combination of the tensile strength, elongation, and electrical conductivity reaching 476.09 MPa, 15.43% and 88.68% IACS respectively when subjected to the optimum thermomechanical treatment, i.e., solution-treating at 920℃ for 1 h, cold drawing to 96% deformation, followed by aging at 400℃ for 3 h. TEM analysis revealed two kinds of finely dispersed precipitates of Cr and CuaZr. It is very important to use the mechanisms of solid solution strengthening, work hardening effect as well as precipitate pinning effect of dislocations to improve tensile strength of the alloy without adversely affecting its electrical conductivity.展开更多
Northeastern China has the second largest expanse of permafrost in China,primarily known as Xing'an-Baikal permafrost.Located on the southeastern edges of the Eurasian cryolithozone,the permafrost is thermally uns...Northeastern China has the second largest expanse of permafrost in China,primarily known as Xing'an-Baikal permafrost.Located on the southeastern edges of the Eurasian cryolithozone,the permafrost is thermally unstable and ecologically sensitive to external changes.The combined impacts of climatic,environmental,and anthropogenic changes cause 3-dimensional degradation of the permafrost.To predict these changes on the southern limit and ground temperature of permafrost in Northeastern China,an equivalent latitude model (ELM) for the mean annual ground surface temperature (MAGSTs) was proposed,and further improved to take into account of the influences of vegetation and snow-cover based on observational data and using the SHAW model.Using the finite element method and assuming a climate warming rate of 0.048°C a-1,the ELM was combined with the unsteady-state heat conduction model to simulate permafrost temperatures at present,and to predict those after 50 and 100 a.The results indicate that at present,sporadic permafrost occurs in the zones with MAGSTs of 1.5°C or colder,and there would still be a significant presence of permafrost in the zones with the present MAGSTs of 0.5°C or colder after 50 a,and in those of-0.5°C or colder after 100 a.Furthermore,the total areal extent of permafrost would decrease from 2.57×105 km2 at present to 1.84×105 km2 after 50 a and to 1.29×105 km2 after 100 a,i.e.,a reduction of 28.4% and 49.8% in the permafrost area,respectively.Also the permafrost would degrade more substantially in the east than in the west.Regional warming and thinning of permafrost would also occur.The area of stable permafrost (mean annual ground temperature,or MAGT≤-1.0°C) would decrease from present 1.07×105 to 8.8×104 km2 after 50 a,and further decrease to 5.6×104 km2 after 100 a.As a result,the unstable permafrost and seasonally frozen ground would expand,and the southern limit of permafrost would shift significantly northwards.The changes in the permafrost environment may adversely affect on ec展开更多
The nitrogen and fluorine co doped TiO 2 polycrystalline powder was synthesized by calcinations of the hydrolysis product of tetra butyl titanate with ammonium fluoride. Nitrogen and fluorine co doping causes the abso...The nitrogen and fluorine co doped TiO 2 polycrystalline powder was synthesized by calcinations of the hydrolysis product of tetra butyl titanate with ammonium fluoride. Nitrogen and fluorine co doping causes the absorption edge of TiO 2 to shift to a lower energy region. The photocatalytic activity of co doped TiO 2 with anatase phases was found to be 2 4 times higher than that of the commercial TiO 2 photocatalyst Degussa P25 for phenol decomposition under visible light irradiation. The co doped TiO 2 powders only contain anatase phases even at 1000℃. Apparently, ammonium fluoride added retarded phase transformation of the TiO 2 powders from anatase to rutile. The substitutional fluorine and interstitial nitrogen atoms in co doped TiO 2 polycrystalline powder were responsible for the vis light response and caused the absorption edge of TiO 2 to shift to a lower energy region.展开更多
The influence of alloying, heat treatment, and plastic working on the performance of Cu-Cr-Zr alloys was investigated. The precipitated phases were characterized as Cr, Cu51Zr14 and Cu5Zr. Cu-Cr-Zr alloys demonstrate ...The influence of alloying, heat treatment, and plastic working on the performance of Cu-Cr-Zr alloys was investigated. The precipitated phases were characterized as Cr, Cu51Zr14 and Cu5Zr. Cu-Cr-Zr alloys demonstrate combination properties of high strength and high conductivity after solution treatment, aging treatment, and plastic deformation. Precipitation course of Cr is the main factor that influences the conductivity of Cu-Cr-Zr alloys, while adding Zr in the alloys adjusts the orientation relationship between Cr and matrix, and tends to increase the conductivity of aged Cu-Cr-Zr alloys after deformation.展开更多
Tea[Camellia sinensis(L.)O.Kuntze]is an important economic crop,and drought is the most important abiotic stress affecting yield and quality.Abscisic acid(ABA)is an important phytohormone responsible for activating dr...Tea[Camellia sinensis(L.)O.Kuntze]is an important economic crop,and drought is the most important abiotic stress affecting yield and quality.Abscisic acid(ABA)is an important phytohormone responsible for activating drought resistance.Increased understanding of ABA effects on tea plant under drought stress is essential to develop drought-tolerant tea genotypes,along with crop management practices that can mitigate drought stress.The objective of the present investigation is evaluation of effects of exogenous ABA on the leaf proteome in tea plant exposed to drought stress.Leaf protein patterns of tea plants under simulated drought stress[(polyethylene glycol(PEG)-treated]and exogenous ABA treatment were analyzed in a time-course experiment using two-dimensional electrophoresis(2-DE),followed by matrix-assisted laser desorption/ionization time-of-flight(MALDI-TOF)mass spectrometry(MS).Among the 72 protein spots identified by MALDI-TOF MS,16 proteins were downregulated and two were upregulated by exogenous ABA.The upregulated proteins have roles in glycolysis and photosystem II stabilization.Twenty-one protein spots were responsive to drought stress and most participate in carbohydrate and nitrogen metabolism,control of reactive oxygen species(ROS),defense,signaling or nucleic acid metabolism.The combined treatments of exogenous ABA and drought showed upregulation of 10 protein spots at 12 h and upregulation of 11 proteins at 72 h after initiation of drought stress.The results support the importance of the role that ABA plays in the tea plant during drought stress,by improving protein transport,carbon metabolism and expression of resistance proteins.展开更多
In this paper, a multi-hop relay channel model based on unmanned aerial vehicles(UAVs) is established by taking into account of the propagation loss, shadowing, and multi-path fading. Based on the proposed channel mod...In this paper, a multi-hop relay channel model based on unmanned aerial vehicles(UAVs) is established by taking into account of the propagation loss, shadowing, and multi-path fading. Based on the proposed channel model, the cascaded propagation loss of relay link and the cascaded probability density function(PDF) of channel fading are derived. Moreover, the theoretical performance of the UAV-based relay system, i.e., the outage probability, bit error rate(BER), and channel capacity, is also analysed and derived. Simulation results show agreement with theoretical results for the hill, mountain, and sea scenarios, indicating the accuracy of both the simulations and derivations.展开更多
Understanding seasonal soil erosion and deposition rates and their spatial distribution along sloping farmlands are necessary for erosion prediction technology and implementing effective soil conservation practices.To...Understanding seasonal soil erosion and deposition rates and their spatial distribution along sloping farmlands are necessary for erosion prediction technology and implementing effective soil conservation practices.To date seasonal change of soil erosion and soil redistribution on long gentle hillsiopes are not fully quantified due to the variable erosive forces in different seasons.A multi-tracer method using rare earth elements(REE)was employed to discriminate seasonal changes of soil erosion and its spatial distribution on a sloping farmland driven by snowmelt runoff,wind force and rainfall-runoff.A long-slope runoff plot with 5 m wide and 320 m long located in the typical Mollisol region of China was divided into eight segments,each of which was 40 m long and tagged with one of eight REE oxides.The spot method of a partial-area tagging scheme was employed and a grid-based layout was used for REE application.Results showed that annual soil erosion rate was 3251.01 km^(-2)for the whole runoff plot,in which snowmelt runoff erosion contributed 537.3 t km^(-2),wind erosion 363.11 km-2 and rainfall-runoff erosion 2350.6 t km^(-2).Surface runoff is the main external erosive force of hillslope soil erosion,accounting for 88.8%of the total annual soil loss.Furthermore,for the eight slope segments of the 320-m long hillslope,the sediment transport ratios of each slope segment caused by snowmelt runoff and rainfall-runoff erosion were more than 23.5%and 34.7%,respectively.The results will enrich the understanding of seasonal soil erosion on long hillsiopes.展开更多
Titanium and titanium alloys have several advantages, but the cost of titanium alloys is very expensive compared with the traditional metal materials. This article introduces two new low-cost titanium alloys Ti-2.1Cr-...Titanium and titanium alloys have several advantages, but the cost of titanium alloys is very expensive compared with the traditional metal materials. This article introduces two new low-cost titanium alloys Ti-2.1Cr-1.3Fe (TCF alloy) and Ti-3Al-2.1Cr-1.3Fe (TACF alloy). In this study, we used Cr-Fe master alloy as one of the raw materials to develop the two new alloys. We introduce the microstructure and tensile properties of the two new alloys from β solution treated with different cooling methods. Optical microscopy (OM), X-ray diffractometry (XRD), and transmission electron microscopy (TEM) were employed to analyze the phase constitution, and scanning electron microscopy (SEM) was used to observe the fracture surfaces. The results indicate that the microstructures consist of β grain boundary and α′ martensite after water quenching (WQ), β matrix and α phase after air cooling (AC) and furnace cooling (FC), respectively. Also, the microstructure is the typical basketweave structures after FC. Of course, athermal ω is also observed by TEM after WQ. The strength increases with decreasing cooling rates and the plasticity is reversed. Because of the athermal ω, the strength and ductility are highest and lowest when the cooling method is WQ. The strength of TACF alloy is higher than the TCF alloy, but the plasticity is lower. The fracture surfaces are almost entirely covered with dimples under the cooling methods of AC and FC. Also, we observe an intergranular fracture area that is generated by athermal ω, although some dimples are observed after WQ.展开更多
Ergothioneine,Ovothiol,and Selenoneine are sulfur/selenium-containing histidine-derived natural products widely distributed across different organisms.They exhibit significant antioxidant properties,making them as pot...Ergothioneine,Ovothiol,and Selenoneine are sulfur/selenium-containing histidine-derived natural products widely distributed across different organisms.They exhibit significant antioxidant properties,making them as potential lead compounds for promoting health.Increasing evidence suggests that Ergothioneine is positively correlated with healthy ageing and longevity.The mechanisms underlying Ergothioneine's regulation of the ageing process at cellular and molecular levels are beginning to be understood.In this review,we provide an in-depth and extensive coverage of the anti-ageing studies on Ergothioneine and discuss its possible intracellular targeting pathways.In addition,we highlight the recent efforts in elucidating the biosynthetic details for Ergothioneine,Ovothiol,and Selenoneine,with a particular focus on the study of their pharmacophore-forming enzymology.展开更多
Surface preparation is potentially important to the corrosion and biomedical properties of NiTi shape memory alloys. The effect of surface preparation on corrosion properties and nickel release of a Ti-56 wt.%Ni alloy...Surface preparation is potentially important to the corrosion and biomedical properties of NiTi shape memory alloys. The effect of surface preparation on corrosion properties and nickel release of a Ti-56 wt.%Ni alloy has been studied. Surface of the NiTi coupons were prepared by four methods, namely, chemical etching, electropolishing, mechanical polishing and oxidizing, and then examined by corrosion test system. Furthermore, the Ni ion releases from NiTi samples with different surface preparations dipped in 1% HCl solution were analysed. Compared with the surface after chemical treatment, mechanical polishing and thermal oxidation, electropolished surface has better corrosion resistance and less nickel release for not only its lower surface roughness, but also the composition and property of its surface film.展开更多
Copper alloy is widely used in high-speed railway,aerospace and other fields due to its excellent electrical conductivity and mechanical properties.High speed deformation and dynamic loading under impact load is a com...Copper alloy is widely used in high-speed railway,aerospace and other fields due to its excellent electrical conductivity and mechanical properties.High speed deformation and dynamic loading under impact load is a complex service condition,which widely exists in the field of national defense,military and industrial application.Therefore,the dynamic deformation behavior of the Cu-20Ag alloy was investigated by Split Hopkinson Pressure Bar(SHPB)with the strain rates of 1000-25000 s^(-1),high-speed hydraulic servo material testing machine with the strain rates of 1-500 s^(-1).The effect of strain rate on flow stress and adiabatic shear sensitivity was analyzed.The results show that the increase of strain rate will increase the flow stress and critical strain,that is to say,the increase of strain rate will reduce the adiabatic shear sensitivity of the Cu-20Ag alloy.The Cu-Ag interface has obvious orientation relationship with;(111)_(Cu)//(111)_(Ag):(^(-)111)_(Cu)//(^(-)111)_(Ag):(^(-)200)_(Cu)//(^(-)200)_(Ag) and [0^(-)11]_(Cu)//[0^(-)11]_(Ag) with the increase of strain rate.The increase of strain rate promotes the precipitation of Ag and increases the number of interfaces in the microstructure,which hinders the movement of dislocations and improves the stress and yield strength of the Cu-20Ag alloy.The concentration and distribution density of dislocations and the precipitation of Ag were the main reasons improve the flow stress and yield strength of the Cu-20Ag alloy.展开更多
The effects of thermomechanical cycling on the shape memory behavior and transformation temperatures of a Ni50.2Ti49.8 alloy under a constant applied stress of 300 MPa were investigated, k is believed that thermomecha...The effects of thermomechanical cycling on the shape memory behavior and transformation temperatures of a Ni50.2Ti49.8 alloy under a constant applied stress of 300 MPa were investigated, k is believed that thermomechanical cycling induces defects such as dislocations, which evidently affect the shape memory behavior and transformation temperatures. The recovery strain decreases with increasing number of thermomechanical cycles, whereas the irreversible plastic strain increases, especially in the initial few cycles. The stored elastic strain energy has an important influence on transformation temperatures, the A5^σ decreases and the M5^σ increases with increasing number of thermomechanical cycles. The recovery strain, irreversible plastic strain, A5^σ , and M5^σ reach a saturation value after several cycles.展开更多
Background Severe acute respiratory syndrome coronavirus (SARS-CoV) is a newly emerging virus that gives rise to SARS patients with high rates of infectivity and fatality. To study the humoral immune responses to SARS...Background Severe acute respiratory syndrome coronavirus (SARS-CoV) is a newly emerging virus that gives rise to SARS patients with high rates of infectivity and fatality. To study the humoral immune responses to SARS-CoV, the authors evaluated IgG and IgM specific antibodies in patients’ sera.Methods Two methods, enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescent assay (IFA), were used to detect specific serum IgG and IgM against SARS-CoV in 98 SARS patients and 250 controls consisting of patients with pneumonia, health-care professionals and healthy subjects. The serum antibody profiles were investigated at different times over one and a half years in 18 of the SARS patients. Results The sensitivity and specificity of ELISA for detecting IgG against SARS-CoV were 100.0% and 97.2% and for IgM 89.8% and 97.6% respectively; the figures using IFA for IgG were 100.0% and 100.0% and for IgM 81.8% and 100.0% respectively. During the first seven days of the antibodies trace test, no IgG and IgM were detected, but on day 15, IgG response increased dramatically, reaching a peak on day 60, remaining high up to day 180 and decreasing gradually until day 540. On day 15, IgM was detected, rapidly reached a peak, then declined gradually until day 180 when IgM was undetectable. Conclusion The detection of antibodies against SARS virus is helpful in the clinical diagnosis of SARS.展开更多
This worked aimed to test the hypothesis that L-alanyl-L-glutamine(Ala-Gln)improves the varicocele-induced testicular injury,which causes male infertility.For this purpose,fifty adult male Wistar rats received the var...This worked aimed to test the hypothesis that L-alanyl-L-glutamine(Ala-Gln)improves the varicocele-induced testicular injury,which causes male infertility.For this purpose,fifty adult male Wistar rats received the varicocele(VC)surgery at the left renal vein.Biomarkers were determined 2,4,and 8 weeks after VC(n=10/each detection).Four weeks after VC,rats received Ala-Gln(1.125 g/kg)treatment with and or saline for 1 week(n=10/each group).Rats in the sham group were also detected for biomarkers at 2,4,and 8 weeks(n=10/each detection).VC caused testicular injury detected by hematoxylin–eosin(H&E)staining,immunohistochemistry,and TUNEL assay.HSP70 mRNA was detected quantitative RT-PCR,SOD,and CAT by nitroblue tetrazolium(NBT)method and 8-OHDG by ELISA.The results showed that varicocele induced injury in the testes.The weight of the left testes was lower than that of the right testes in VC-bearing rats(p<0.01).The relative numbers of sustentacular and spermatogenic cells were decreased after VC(p<0.01).In sham-4 wk,VC-4wk,VC-5wk and Ala-Gln groups,the apoptosis index was 5.10±1.14,13.22±3.63,33.62±3.56 and 22.33±2.61,relative level of HSP70 mRNA 1.00±0.12,0.53±0.05,0.51±0.04 and 1.62±0.15 fold,SOD 16.4±0.23,13.4±0.17,10.01±1.06 and 19.53±2.26 U/mg protein,CAT 2.16±0.31,1.07±0.28,and 1.31±0.26 and 3.46±0.71 U/mg,8-OHDG 5.23±0.67,6.81±0.78,7.16±1.22 and 4.14±0.73 pg/μg DNA,respectively(p<0.01).Our results suggest that Ala-Gln prevented the VC-induced testicular injury.We have firstly reported that Ala-Gln protects against varicocele-induced testicular injuries by up-regulation of HSP70 and antioxidants,SOD and CAT,and down-regulation of oxidant 8-OHDG,resulting in reducing apoptosis in the testis.展开更多
The addition of 3%~9% Zr on the martensitic transformation of Ti-18Nb(at.%) alloy was investigated. The results of microstructure and X-ray diffraction (XRD) analysis show that the phase constitution of as-quenched T...The addition of 3%~9% Zr on the martensitic transformation of Ti-18Nb(at.%) alloy was investigated. The results of microstructure and X-ray diffraction (XRD) analysis show that the phase constitution of as-quenched Ti-18Nb-9Zr(at.%) alloy consists of the retained matrix and martensite, while that of the other three alloys is single martensite. No trace of athermal phase was found in any of the as-quenched alloys. Unlike the effect of Nb addition on the martensitic transformation start temperature Ms of Ti-18Nb(at.%) alloy, Ms de-creased nonlinearly as increasing the Zr addition from 3% to 9% and Ms decreased much more sharply as increasing the Zr addition. The Ms of as-quenched Ti-18Nb-9Zr alloy was around room temperature. The effect of Zr addition on the phase stabilizing in the Ti-18Nb(at.%) alloy was briefly discussed.展开更多
基金This research was supported by The National Natural Science Foundation of China(31370688,31400584)the earmarked fund for China Agriculture Research System(CARS-19)+1 种基金Jiangsu Agriculture Science and Technology Innovation Fund(CX(16)1047)Keypoint Research and Invention Program of Jiangsu Province(BE2016417)and FuJian Province“2011 Collaborative Innovation Center”Chinese Oolong Tea Industry Innovation Center(Cultivation)special project(J2015-75).
文摘Purple-leaf tea plants,as anthocyanin-rich cultivars,are valuable materials for manufacturing teas with unique colors or flavors.In this study,a new purple-leaf cultivar“Zixin”(“ZX”)was examined,and its biochemical variation and mechanism of leaf color change were elucidated.The metabolomes of leaves of“ZX”at completely purple,intermediately purple,and completely green stages were analyzed using ultra-performance liquid chromatography quadrupole time of flight mass spectrometry(UPLC-QTOF-MS).Metabolites in the flavonoid biosynthetic pathway remained at high levels in purple leaves,whereas intermediates of porphyrin and chlorophyll metabolism and carotenoid biosynthesis exhibited high levels in green leaves.In addition,fatty acid metabolism was more active in purple leaves,and steroids maintained higher levels in green leaves.Saponin,alcohol,organic acid,and terpenoid-related metabolites also changed significantly during the leaf color change process.Furthermore,the substance changes between“ZX”and“Zijuan”(a thoroughly studied purple-leaf cultivar)were also compared.The leaf color change in“Zijuan”was mainly caused by a decrease in flavonoids/anthocyanins.However,a decrease in flavonoids/anthocyanins,an enhancement of porphyrin,chlorophyll metabolism,carotenoid biosynthesis,and steroids,and a decrease in fatty acids synergistically caused the leaf color change in“ZX”.These findings will facilitate comprehensive research on the regulatory mechanisms of leaf color change in purple-leaf tea cultivars.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China (Grant Nos. 40901202, 40925004), and the National High Technology Research and Development Program of China (Grant No. 2009AA122104). The input data for WRF model are from the Research Data Archive (RDA) which is maintained by the Computational and Information Systems Laboratory (CISL) at the National Center for Atmo- spheric Research (NCAR). The original data are available from the RDA (http://dss.ucar.edu) in Dataset No. ds083.2.
文摘The spatial resolution of general circulation models (GCMs) is too coarse to represent regional climate variations at the regional, basin, and local scales required for many environmental modeling and impact assessments. Weather research and forecasting model (WRF) is a nextgeneration, fully compressible, Euler non-hydrostatic mesoscale forecast model with a runtime hydrostatic option. This model is useful for downscaling weather and climate at the scales from one kilometer to thousands of kilometers, and is useful for deriving meteorological parameters required for hydrological simulation too. The objective of this paper is to validate WRF simulating 5 km/ 1 h air temperatures by daily observed data of China Meteorological Administration (CMA) stations, and by hourly in-situ data of the Watershed Allied Telemetry Experimental Research Project. The daily validation shows that the WRF simulation has good agreement with the observed data; the R2 between the WRF simulation and each station is more than 0.93; the absolute of meanbias error (MBE) for each station is less than 2℃; and the MBEs of Ejina, Mazongshan and Alxa stations are near zero, with R2 is more than 0.98, which can be taken as an unbiased estimation. The hourly validation shows that the WRF simulation can capture the basic trend of observed data, the MBE of each site is approximately 2℃, the R2 of each site is more than 0.80, with the highest at 0.95, and the computed and observed surface air temperature series show a significantly similar trend.
基金financially supported by the National High-Tech Research and Development Program of China (No.2006AA03Z522)the National Natural Science Foundation of China (No.50704006)the Technology De-velopment Fund of CHALCO (No.CHINACO-2009-KJ-02)
文摘The effects of thermomechanical treatment on the properties and microstructure of Cu-Cr-Zr alloy and Cu-Cr-Zr-Ag alloy were investigated. Ag addition improves the mechanical properties of the alloy through solid solution strengthening and brings a little effect on the electrical conductivity of the alloy. A new Cu-Cr-Zr-Ag alloy was developed, which has an excellent combination of the tensile strength, elongation, and electrical conductivity reaching 476.09 MPa, 15.43% and 88.68% IACS respectively when subjected to the optimum thermomechanical treatment, i.e., solution-treating at 920℃ for 1 h, cold drawing to 96% deformation, followed by aging at 400℃ for 3 h. TEM analysis revealed two kinds of finely dispersed precipitates of Cr and CuaZr. It is very important to use the mechanisms of solid solution strengthening, work hardening effect as well as precipitate pinning effect of dislocations to improve tensile strength of the alloy without adversely affecting its electrical conductivity.
基金supported by National Natural Science Foundation of China (Grant Nos. 40821001 and 40701013)Chinese Academy of Sciences (CAS) Knowledge Innovative Program (Grant No. KZCX2-YW- 311)CAS ‘One Hundred Talented People’ Program
文摘Northeastern China has the second largest expanse of permafrost in China,primarily known as Xing'an-Baikal permafrost.Located on the southeastern edges of the Eurasian cryolithozone,the permafrost is thermally unstable and ecologically sensitive to external changes.The combined impacts of climatic,environmental,and anthropogenic changes cause 3-dimensional degradation of the permafrost.To predict these changes on the southern limit and ground temperature of permafrost in Northeastern China,an equivalent latitude model (ELM) for the mean annual ground surface temperature (MAGSTs) was proposed,and further improved to take into account of the influences of vegetation and snow-cover based on observational data and using the SHAW model.Using the finite element method and assuming a climate warming rate of 0.048°C a-1,the ELM was combined with the unsteady-state heat conduction model to simulate permafrost temperatures at present,and to predict those after 50 and 100 a.The results indicate that at present,sporadic permafrost occurs in the zones with MAGSTs of 1.5°C or colder,and there would still be a significant presence of permafrost in the zones with the present MAGSTs of 0.5°C or colder after 50 a,and in those of-0.5°C or colder after 100 a.Furthermore,the total areal extent of permafrost would decrease from 2.57×105 km2 at present to 1.84×105 km2 after 50 a and to 1.29×105 km2 after 100 a,i.e.,a reduction of 28.4% and 49.8% in the permafrost area,respectively.Also the permafrost would degrade more substantially in the east than in the west.Regional warming and thinning of permafrost would also occur.The area of stable permafrost (mean annual ground temperature,or MAGT≤-1.0°C) would decrease from present 1.07×105 to 8.8×104 km2 after 50 a,and further decrease to 5.6×104 km2 after 100 a.As a result,the unstable permafrost and seasonally frozen ground would expand,and the southern limit of permafrost would shift significantly northwards.The changes in the permafrost environment may adversely affect on ec
文摘The nitrogen and fluorine co doped TiO 2 polycrystalline powder was synthesized by calcinations of the hydrolysis product of tetra butyl titanate with ammonium fluoride. Nitrogen and fluorine co doping causes the absorption edge of TiO 2 to shift to a lower energy region. The photocatalytic activity of co doped TiO 2 with anatase phases was found to be 2 4 times higher than that of the commercial TiO 2 photocatalyst Degussa P25 for phenol decomposition under visible light irradiation. The co doped TiO 2 powders only contain anatase phases even at 1000℃. Apparently, ammonium fluoride added retarded phase transformation of the TiO 2 powders from anatase to rutile. The substitutional fluorine and interstitial nitrogen atoms in co doped TiO 2 polycrystalline powder were responsible for the vis light response and caused the absorption edge of TiO 2 to shift to a lower energy region.
基金This project is financially supported by the National High-Tech Research and Development Program of China (No. 2004AA3Z1460).
文摘The influence of alloying, heat treatment, and plastic working on the performance of Cu-Cr-Zr alloys was investigated. The precipitated phases were characterized as Cr, Cu51Zr14 and Cu5Zr. Cu-Cr-Zr alloys demonstrate combination properties of high strength and high conductivity after solution treatment, aging treatment, and plastic deformation. Precipitation course of Cr is the main factor that influences the conductivity of Cu-Cr-Zr alloys, while adding Zr in the alloys adjusts the orientation relationship between Cr and matrix, and tends to increase the conductivity of aged Cu-Cr-Zr alloys after deformation.
基金This work was supported by the National Natural Science Foundation of China(30800884,31370688)the Jiangsu Science and Technology Program of China(BE2011319).
文摘Tea[Camellia sinensis(L.)O.Kuntze]is an important economic crop,and drought is the most important abiotic stress affecting yield and quality.Abscisic acid(ABA)is an important phytohormone responsible for activating drought resistance.Increased understanding of ABA effects on tea plant under drought stress is essential to develop drought-tolerant tea genotypes,along with crop management practices that can mitigate drought stress.The objective of the present investigation is evaluation of effects of exogenous ABA on the leaf proteome in tea plant exposed to drought stress.Leaf protein patterns of tea plants under simulated drought stress[(polyethylene glycol(PEG)-treated]and exogenous ABA treatment were analyzed in a time-course experiment using two-dimensional electrophoresis(2-DE),followed by matrix-assisted laser desorption/ionization time-of-flight(MALDI-TOF)mass spectrometry(MS).Among the 72 protein spots identified by MALDI-TOF MS,16 proteins were downregulated and two were upregulated by exogenous ABA.The upregulated proteins have roles in glycolysis and photosystem II stabilization.Twenty-one protein spots were responsive to drought stress and most participate in carbohydrate and nitrogen metabolism,control of reactive oxygen species(ROS),defense,signaling or nucleic acid metabolism.The combined treatments of exogenous ABA and drought showed upregulation of 10 protein spots at 12 h and upregulation of 11 proteins at 72 h after initiation of drought stress.The results support the importance of the role that ABA plays in the tea plant during drought stress,by improving protein transport,carbon metabolism and expression of resistance proteins.
基金supported by the National Key Scientific Instrument and Equipment Development Project(Grant No.2013YQ200607)China NSF Grants(Grant No.61631020)+2 种基金Aeronautical Science Foundation of China(Grant No.2017ZC52021)Fundamental Research Funds for the Central Universities(Grant No.NJ20160027)Open Foundation for Graduate Innovation of NUAA(Grant No.kfjj20160412 and kfjj20170405)
文摘In this paper, a multi-hop relay channel model based on unmanned aerial vehicles(UAVs) is established by taking into account of the propagation loss, shadowing, and multi-path fading. Based on the proposed channel model, the cascaded propagation loss of relay link and the cascaded probability density function(PDF) of channel fading are derived. Moreover, the theoretical performance of the UAV-based relay system, i.e., the outage probability, bit error rate(BER), and channel capacity, is also analysed and derived. Simulation results show agreement with theoretical results for the hill, mountain, and sea scenarios, indicating the accuracy of both the simulations and derivations.
基金supported by the National Key R&D Program of China(No.2016YFE0202900)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA23060502)the National Natural Science Foundation of China(No.41571263).
文摘Understanding seasonal soil erosion and deposition rates and their spatial distribution along sloping farmlands are necessary for erosion prediction technology and implementing effective soil conservation practices.To date seasonal change of soil erosion and soil redistribution on long gentle hillsiopes are not fully quantified due to the variable erosive forces in different seasons.A multi-tracer method using rare earth elements(REE)was employed to discriminate seasonal changes of soil erosion and its spatial distribution on a sloping farmland driven by snowmelt runoff,wind force and rainfall-runoff.A long-slope runoff plot with 5 m wide and 320 m long located in the typical Mollisol region of China was divided into eight segments,each of which was 40 m long and tagged with one of eight REE oxides.The spot method of a partial-area tagging scheme was employed and a grid-based layout was used for REE application.Results showed that annual soil erosion rate was 3251.01 km^(-2)for the whole runoff plot,in which snowmelt runoff erosion contributed 537.3 t km^(-2),wind erosion 363.11 km-2 and rainfall-runoff erosion 2350.6 t km^(-2).Surface runoff is the main external erosive force of hillslope soil erosion,accounting for 88.8%of the total annual soil loss.Furthermore,for the eight slope segments of the 320-m long hillslope,the sediment transport ratios of each slope segment caused by snowmelt runoff and rainfall-runoff erosion were more than 23.5%and 34.7%,respectively.The results will enrich the understanding of seasonal soil erosion on long hillsiopes.
基金financially sponsored by the International Science and Technology Cooperation Project (No.2010DFA52280)
文摘Titanium and titanium alloys have several advantages, but the cost of titanium alloys is very expensive compared with the traditional metal materials. This article introduces two new low-cost titanium alloys Ti-2.1Cr-1.3Fe (TCF alloy) and Ti-3Al-2.1Cr-1.3Fe (TACF alloy). In this study, we used Cr-Fe master alloy as one of the raw materials to develop the two new alloys. We introduce the microstructure and tensile properties of the two new alloys from β solution treated with different cooling methods. Optical microscopy (OM), X-ray diffractometry (XRD), and transmission electron microscopy (TEM) were employed to analyze the phase constitution, and scanning electron microscopy (SEM) was used to observe the fracture surfaces. The results indicate that the microstructures consist of β grain boundary and α′ martensite after water quenching (WQ), β matrix and α phase after air cooling (AC) and furnace cooling (FC), respectively. Also, the microstructure is the typical basketweave structures after FC. Of course, athermal ω is also observed by TEM after WQ. The strength increases with decreasing cooling rates and the plasticity is reversed. Because of the athermal ω, the strength and ductility are highest and lowest when the cooling method is WQ. The strength of TACF alloy is higher than the TCF alloy, but the plasticity is lower. The fracture surfaces are almost entirely covered with dimples under the cooling methods of AC and FC. Also, we observe an intergranular fracture area that is generated by athermal ω, although some dimples are observed after WQ.
基金supported by grants from the National Key R&D Program of China(No.2018YFA0903200 to C.Z.)the National Natural Science Foundation of China(Nos.32270032 and 32070038 to C.Z.,No.32000029 to L.C.).
文摘Ergothioneine,Ovothiol,and Selenoneine are sulfur/selenium-containing histidine-derived natural products widely distributed across different organisms.They exhibit significant antioxidant properties,making them as potential lead compounds for promoting health.Increasing evidence suggests that Ergothioneine is positively correlated with healthy ageing and longevity.The mechanisms underlying Ergothioneine's regulation of the ageing process at cellular and molecular levels are beginning to be understood.In this review,we provide an in-depth and extensive coverage of the anti-ageing studies on Ergothioneine and discuss its possible intracellular targeting pathways.In addition,we highlight the recent efforts in elucidating the biosynthetic details for Ergothioneine,Ovothiol,and Selenoneine,with a particular focus on the study of their pharmacophore-forming enzymology.
文摘Surface preparation is potentially important to the corrosion and biomedical properties of NiTi shape memory alloys. The effect of surface preparation on corrosion properties and nickel release of a Ti-56 wt.%Ni alloy has been studied. Surface of the NiTi coupons were prepared by four methods, namely, chemical etching, electropolishing, mechanical polishing and oxidizing, and then examined by corrosion test system. Furthermore, the Ni ion releases from NiTi samples with different surface preparations dipped in 1% HCl solution were analysed. Compared with the surface after chemical treatment, mechanical polishing and thermal oxidation, electropolished surface has better corrosion resistance and less nickel release for not only its lower surface roughness, but also the composition and property of its surface film.
基金financially supported by the Innovation Leading Project of Henan Province (No. 191110210400)the Key Scientific Research Projects of Colleges and Universities in Henan Province (No. 19A430012)+3 种基金the Luoyang Science and Technology Major Project (No. 1901006A)the Henan Outstanding Talents Innovation Fund (182101510003)National Key R&D Plan (No. 2016YFB0301400)National Key R&D Plan (No.2017YFB0306400)
文摘Copper alloy is widely used in high-speed railway,aerospace and other fields due to its excellent electrical conductivity and mechanical properties.High speed deformation and dynamic loading under impact load is a complex service condition,which widely exists in the field of national defense,military and industrial application.Therefore,the dynamic deformation behavior of the Cu-20Ag alloy was investigated by Split Hopkinson Pressure Bar(SHPB)with the strain rates of 1000-25000 s^(-1),high-speed hydraulic servo material testing machine with the strain rates of 1-500 s^(-1).The effect of strain rate on flow stress and adiabatic shear sensitivity was analyzed.The results show that the increase of strain rate will increase the flow stress and critical strain,that is to say,the increase of strain rate will reduce the adiabatic shear sensitivity of the Cu-20Ag alloy.The Cu-Ag interface has obvious orientation relationship with;(111)_(Cu)//(111)_(Ag):(^(-)111)_(Cu)//(^(-)111)_(Ag):(^(-)200)_(Cu)//(^(-)200)_(Ag) and [0^(-)11]_(Cu)//[0^(-)11]_(Ag) with the increase of strain rate.The increase of strain rate promotes the precipitation of Ag and increases the number of interfaces in the microstructure,which hinders the movement of dislocations and improves the stress and yield strength of the Cu-20Ag alloy.The concentration and distribution density of dislocations and the precipitation of Ag were the main reasons improve the flow stress and yield strength of the Cu-20Ag alloy.
基金supported in part by the Department of Physics,Peking Universityin part by the Center for Research and Development of Superconductivity in China under contract No.BKBRSF-G19990646-02
文摘The effects of thermomechanical cycling on the shape memory behavior and transformation temperatures of a Ni50.2Ti49.8 alloy under a constant applied stress of 300 MPa were investigated, k is believed that thermomechanical cycling induces defects such as dislocations, which evidently affect the shape memory behavior and transformation temperatures. The recovery strain decreases with increasing number of thermomechanical cycles, whereas the irreversible plastic strain increases, especially in the initial few cycles. The stored elastic strain energy has an important influence on transformation temperatures, the A5^σ decreases and the M5^σ increases with increasing number of thermomechanical cycles. The recovery strain, irreversible plastic strain, A5^σ , and M5^σ reach a saturation value after several cycles.
文摘Background Severe acute respiratory syndrome coronavirus (SARS-CoV) is a newly emerging virus that gives rise to SARS patients with high rates of infectivity and fatality. To study the humoral immune responses to SARS-CoV, the authors evaluated IgG and IgM specific antibodies in patients’ sera.Methods Two methods, enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescent assay (IFA), were used to detect specific serum IgG and IgM against SARS-CoV in 98 SARS patients and 250 controls consisting of patients with pneumonia, health-care professionals and healthy subjects. The serum antibody profiles were investigated at different times over one and a half years in 18 of the SARS patients. Results The sensitivity and specificity of ELISA for detecting IgG against SARS-CoV were 100.0% and 97.2% and for IgM 89.8% and 97.6% respectively; the figures using IFA for IgG were 100.0% and 100.0% and for IgM 81.8% and 100.0% respectively. During the first seven days of the antibodies trace test, no IgG and IgM were detected, but on day 15, IgG response increased dramatically, reaching a peak on day 60, remaining high up to day 180 and decreasing gradually until day 540. On day 15, IgM was detected, rapidly reached a peak, then declined gradually until day 180 when IgM was undetectable. Conclusion The detection of antibodies against SARS virus is helpful in the clinical diagnosis of SARS.
文摘This worked aimed to test the hypothesis that L-alanyl-L-glutamine(Ala-Gln)improves the varicocele-induced testicular injury,which causes male infertility.For this purpose,fifty adult male Wistar rats received the varicocele(VC)surgery at the left renal vein.Biomarkers were determined 2,4,and 8 weeks after VC(n=10/each detection).Four weeks after VC,rats received Ala-Gln(1.125 g/kg)treatment with and or saline for 1 week(n=10/each group).Rats in the sham group were also detected for biomarkers at 2,4,and 8 weeks(n=10/each detection).VC caused testicular injury detected by hematoxylin–eosin(H&E)staining,immunohistochemistry,and TUNEL assay.HSP70 mRNA was detected quantitative RT-PCR,SOD,and CAT by nitroblue tetrazolium(NBT)method and 8-OHDG by ELISA.The results showed that varicocele induced injury in the testes.The weight of the left testes was lower than that of the right testes in VC-bearing rats(p<0.01).The relative numbers of sustentacular and spermatogenic cells were decreased after VC(p<0.01).In sham-4 wk,VC-4wk,VC-5wk and Ala-Gln groups,the apoptosis index was 5.10±1.14,13.22±3.63,33.62±3.56 and 22.33±2.61,relative level of HSP70 mRNA 1.00±0.12,0.53±0.05,0.51±0.04 and 1.62±0.15 fold,SOD 16.4±0.23,13.4±0.17,10.01±1.06 and 19.53±2.26 U/mg protein,CAT 2.16±0.31,1.07±0.28,and 1.31±0.26 and 3.46±0.71 U/mg,8-OHDG 5.23±0.67,6.81±0.78,7.16±1.22 and 4.14±0.73 pg/μg DNA,respectively(p<0.01).Our results suggest that Ala-Gln prevented the VC-induced testicular injury.We have firstly reported that Ala-Gln protects against varicocele-induced testicular injuries by up-regulation of HSP70 and antioxidants,SOD and CAT,and down-regulation of oxidant 8-OHDG,resulting in reducing apoptosis in the testis.
基金supported by the SinoKorea International Cooperative Research Project (No. 2010DFA52280)
文摘The addition of 3%~9% Zr on the martensitic transformation of Ti-18Nb(at.%) alloy was investigated. The results of microstructure and X-ray diffraction (XRD) analysis show that the phase constitution of as-quenched Ti-18Nb-9Zr(at.%) alloy consists of the retained matrix and martensite, while that of the other three alloys is single martensite. No trace of athermal phase was found in any of the as-quenched alloys. Unlike the effect of Nb addition on the martensitic transformation start temperature Ms of Ti-18Nb(at.%) alloy, Ms de-creased nonlinearly as increasing the Zr addition from 3% to 9% and Ms decreased much more sharply as increasing the Zr addition. The Ms of as-quenched Ti-18Nb-9Zr alloy was around room temperature. The effect of Zr addition on the phase stabilizing in the Ti-18Nb(at.%) alloy was briefly discussed.