Impact of climate and human activity on NDVI of various vegetation types in the Three-River Source Region, China

The Three-River Source Region(TRSR)in China holds a vital position and exhibits an irreplaceable strategic importance in ecological preservation at the national level.On the basis of an in-depth study of the vegetation evolution in the TRSR from 2000 to 2022,we conducted a detailed analysis of the feedback mechanism of vegetation growth to climate change and human activity for different vegetation types.During the growing season,the spatiotemporal variations of normalized difference vegetation index(NDVI)for different vegetation types in the TRSR were analyzed using the Moderate Resolution Imaging Spectroradiometer(MODIS)-NDVI data and meteorological data from 2000 to 2022.In addition,the response characteristics of vegetation to temperature,precipitation,and human activity were assessed using trend analysis,partial correlation analysis,and residual analysis.Results indicated that,after in-depth research,from 2000 to 2022,the TRSR's average NDVI during the growing season was 0.3482.The preliminary ranking of the average NDVI for different vegetation types was as follows:shrubland(0.5762)>forest(0.5443)>meadow(0.4219)>highland vegetation(0.2223)>steppe(0.2159).The NDVI during the growing season exhibited a fluctuating growth trend,with an average growth rate of 0.0018/10a(P<0.01).Notably,forests displayed a significant development trend throughout the growing season,possessing the fastest rate of change in NDVI(0.0028/10a).Moreover,the upward trends in NDVI for forests and steppes exhibited extensive spatial distributions,with significant increases accounting for 95.23%and 93.80%,respectively.The sensitivity to precipitation was significantly enhanced in other vegetation types other than highland vegetation.By contrast,steppes,meadows,and highland vegetation demonstrated relatively high vulnerability to temperature fluctuations.A further detailed analysis revealed that climate change had a significant positive impact on the TRSR from 2000 to 2022,particularly in its northwestern areas,accounting for 85.05%of the total area.Meanwhile,human activity played a notable positive role in the southwestern and southeastern areas of the TRSR,covering 62.65%of the total area.Therefore,climate change had a significantly higher impact on NDVI during the growing season in the TRSR than human activity.

Effects of process parameters and annealing on microstructure and properties of CoCrFeMnNi high-entropy alloy coating prepared by plasma cladding

Plasma cladding was used to prepare a CoCrFeMnNi high-entropy alloy(HEA)coating under different conditions.The process parameters were optimized using an orthogonal experiment design based on surface morphology quality characteristics,dilution rate,and hardness.The optimal process parameters were determined through range and variance analysis to be a cladding current of 70 A,a cladding speed of 7 cm·min^(-1),and a powder gas flow rate of 8 L·s^(-1).During the optimized experiments,both the cladded and annealed CoCrFeMnNi HEA coatings exhibit some pores,micro-voids,and a small amount of aggregation.However,the aggregation in the annealed coating is more dispersed than that in the cladded coating.The cladded CoCrFeMnNi HEA coating consists of simple FCC phases,while a new Cr-rich phase precipitates from the FCC matrix after annealing the coating at a temperature range of 550°C-950°C.After annealing at 850°C,the proportion of the FCC phase decreases compared to the cladded coating,and the number of large-angle grain boundaries is significantly reduced.However,the proportion of grains with sizes below 50μm increases from 61.7%to 74.3%.The micro-hardness and wear resistance of the cladded coating initially increases but then decreases with an increase in annealing temperature,indicating that appropriate annealing can significantly improve the mechanical properties of the CoCrFeMnNi HEA coatings by plasma cladding.The micro-hardness of the CoCrFeMnNi HEA coatings after annealing at 650°C increases to 274.82 HV_(0.2),while the friction coefficient decreases to below 0.595.

Leaching process of rare earths from weathered crust elution-deposited rare earth ore

In order to strengthen the leaching procedure,the chemical processes of leaching rare earths (RE) from the weathered crust elution-deposited rare earth ore were investigated frow the viewpoints of kinetics,hydrodynamic and mass transfer.The results show that the leaching hydrodynamics follows the Darcy law.The leaching kinetics can be described by the shrinking core model;the leaching process is controlled by diffusion of porous solid layer;and the mass transfer can be described with Van Deemter equation.This provides a theoretic basis and a scientific approach with high efficiency and optimized extraction conditions in industrial practice.

Microstructure and properties of WC-12Co composite coatings prepared by laser cladding

A comprehensive study of the phase composition, microstructure evolution, microhardness and wear performance of WC-12 Co composite coatings fabricated by laser cladding using coaxial powder-feed mode was presented. It was shown that a combination of high scan speed and high laser energy density made WC on the edge of WC-12 Co composite powders partially melt in liquid Co and 304 stainless steel matrix, and then new carbides consisting of lamellar WC and herringbone M3 W3 C(M=Fe,Co) were formed. Meanwhile, WC-12 Co composite coatings with no porosity, cracks and drawbacks like decarburization were obtained, showing high densification and good metallurgical bonding with the substrate. Furthermore, a considerably high microhardness of HV0.3 1500-1600, low coefficient of friction of 0.55 and wear rate of(2.15±0.31)×10-7 mm3/(N·m) were achieved owing to the synergistic effect of excellent metallurgical bonding and fine microstructures of composite coating under laser power of 1500 W.

Effect of Boron and Cerium on Microstructures and Properties of Cu-Fe-P Alloy

The effects of B and Ce on the removal of inclusions, microstructures, and properties of Cu-Fe-P alloys were studied. Certain impurity elements and the microstructures, mechanical properties, and conductivity of four experimental alloys, Cu-0.22Fe-0.06P, Cu-0.22Fe-0.06P-0.05Ce, Cu-0.22Fe-0.06P-0.02B, and Cu-0.22Fe-0.06P-0.05Ce-0. 02B （ %, mass fraction）, were tested and analyzed. Results show that on one hand, B and Ce have a remarkable function of removing S, Pb, and Bi from copper alloys ; on the other hand, the recrystallization temperature of the Cu-Fe-P alloy is considerably increased by adding trace B and Ce, resulting in the combined strengthening effect of precipitation hardening and cold work hardening after cold working and aging, while the negative effect of B and Ce on conductivity is slight. Therefore, a good combination of high strength and conductivity is achieved.

Simulation of one-dimensional column leaching of weathered crust elution-deposited rare earth ore

The ion exchange model of the leaching process was determined via batch leaching experiments using the Kerr model, with the selectivity coefficient experimentally determined to be 12.59×10^-10 L^2/g^2. Solute transport laws of ammonium ions (NH4 +) and rare earth ions (RE^3+) in column leaching were described by the convection-dispersion equation (CDE). The source and sink in the CDE were determined by the Kerr model. The CDE with strong nonlinearity was solved using the sequential non-iterative method. Compared with the breakthrough curve of RE^3+, the correlation coefficient between the simulated and experimental curves reached 0.8724. Therefore, this method can simulate the one-dimensional column leaching of weathered crust elution-deposited rare earth ore. Moreover, the effects of different concentrations of ammonium sulfate ((NH4)2SO4) solution on the leaching rate of rare earth were analyzed. The optimal concentration of the (NH4)2SO4 solution had a linear relationship with the rare earth grade.

Kinetics of Leaching Flavonoids from Pueraria Lobata with Ethanol

The kinetics of leaching flavonoids from Pueraria Lobata with ethanol was investigated. The effects of leaching temperature, mechanical agitation rate, concentration of ethanol and feed particle size on leaching kinetics were examined. It is found that the smaller the feed particle size or the higher the leaching temperature, the higher the leaching rate. The leaching process can be described by the shrinking-core model. The apparent activation energy is 10.8kJ·mol^-1, suggesting that the leaching process is controlled by the inner diffusion. An empirical equation relating the flavonoids leaching rate constant to the feed particle size and leaching temperature was expected.

Primary Establishment of the Tissue Culture Technique and Regeneration System for Ornamental Lupinns polyphyllus

The purpose of this paper is to develop a system for tissue culture and rapid propagation of two ornamental lupins, Minaretie and Russell Prize. In view of screening out the better explant regeneration and suitable culture medium, through adding hormone 6-BA, NAA and 2, 4-D into MS and B5 basic culture medium, a series of experiments were carried out with the shoot tips, leaves, leaf petioles and stems from the asepsis seedling. The results showed that the shoot tips had favorableness on the rapidly propagation; MS＋6-BA 0.5 mg. L-1 for first generation, the induction rate of Minaretie and Russell Prize was 90.5% and 95.86% respectivdy; Minaretie had the highest propagation index （6.35） on MS＋6-BA 0.5 mg.L^-1＋NAA 0 mg-L^-1＋GA 30.8 mg. L^1＋AC 2 g. L^-1, but Russell Prize had the highest propagation index （7.24） on MS＋6-BA 0.5 mg.L^-1＋NAA 0.15 mg.L^-1＋GA3 1.0 mg.L^-1＋AC 0.5 g.L^-1; 1/2 MS＋NAA 0.25 mg.L^-1 was the best rooting medium. The ratios of getting roots of Minaretie and Russell Prize were 94.78% and 96.32%, respectively.

Preparation of crystalline rare earth carbonates with large particle size from the lixivium of weathered crust elution-deposited rare earth ores

Crystalline rare-earth(RE)carbonates having large particle size were prepared from the lixivium of weathered crust elution-deposited rare-earth ores using the precipitation method with ammonium bicarbonate as the precipitant.Their chemical composition was studied using elemental and thermogravimetric analyses(TGA),and their structure and morphology were characterized using Fourier transform infrared(FTIR)spectroscopy,X-ray diffraction(XRD),and scanning electron microscopy(SEM).The results demonstrate that the crystalline rareearth carbonate is a hydrated basic carbonate or oxycarbonate and not astable intermediate carbonate in the process of thermal decomposition.The particle size of crystalline rare-earth carbonates with large particle size is in the range of 50–200μm.With an RE2O3 content of up to 95wt%,the quality of crystalline rare-earth carbonates is higher compared to the Chinese National Standard(GB/T 28882–2012).The quality of the product is superior to the Chinese National Standard.

Isolation and characterization of YNTC-1,a novel Alicyclobacillus sendaiensis strain

A heterotrophic acidothermophilic bacterial strain,YNTC-1,was isolated from an acidic hot spring in Tengchong,Yunan,China.YNTC-1 grows at pH value of 1.5-8.0 and temperature of 40-70℃,with optimal pH and temperature at 3.0 and 55℃,respectively.The cells of the strain are in shape of short rod,with 1.0-1.2μm in length and 0.7-0.8μm in diameter,and with distinct spores at both poles of each cell.The predominant fatty acids in cellular membrane of the strain are C18:1ω7c.16s rRNA gene analysis reveals that this strain is closely related to Alicyclobacillus sendaiensis,with over 99%sequence similarity.Based on phenotypic and genotypic analyses,YNTC-1 is identified as a member of A.sendaiensis.Considering some important morphological and biochemical differences between strain YNTC-1 and A.sendaiensis ATCC 27009T,YNTC-1 may be proposed to be a novel subspecies of A.sendaiensis.However,this viewpoint has to be confirmed by further studies.Co-bioleaching of pyrite and chalcopyrite with strain YN22,Sulfobacillus thermosulfidooxidans,shows that strain YNTC-1 has no evident influence on bioleaching rates of these two sulphide minerals.

Synthesis of polystyrene-styrene/butadiene diblock copolymers via reversible addition-fragmentation chain transfer miniemulsion polymerization

Polystyrene-styrene/butadiene diblock copolymers were synthesized via reversible addition-fragmentation chain transfer （RAFT） miniemulsion polymerization.During the polymerization process,the molecular weight distribution was narrow and the numerical molecular weight of the copolymers increased with increasing conversion of monomers,which was close to the theoretical.FT-IR and ^1H NMR results indicated that the microstructure of the polymer was mainly 1,4-trans-butadiene with small amount of 1,2-units,and composition in the copolymers was obtained.

Kinetics of Leaching Flavonoids from Pueraria Lobata with Ethanol

The kinetics of leaching flavonoids from Pueraria Lobata with ethanol was investigated. The effects of leaching temperature, mechanical agitation rate,concentration of ethanol and feed particle size on leaching kinetics were examined.It is found that the smaller the feed particle size or the higher the leaching temperature,the higher the leaching rate. The leaching process can be described by the shrinking-core model. The apparent activation en- ergy is 10.8kJ·mol-1, suggesting that the leaching process is controlled by the inner diffusion. An empirical equa- tion relating the flavonoids leaching rate constant to the feed particle size and leaching temperature was expected.

Preparation and Structure Characterization of Rare Earth Doped Alumina-Siloxane Gel and Its Modification on ER Effect

A series of samples of alumina-siloxane gel wrapped by poly (methyl methacrylate) and doped with rare earths such as lanthanum, praseodymium, yttrium, gadolinium and europium were prepared. The structure features were characterized by micrograph, X-ray fluorescence spectrum, X-ray diffraction spectrum, Fourier transform infrared spectrum and differential thermal analysis. Tests indicate that rare earths modify the electrorheological effects of the stable suspensions composed of samples stirred with silicon oil.

Effect of Samarium(Sm)Addition on Microstructure and Mechanical Properties of Al-5Cu Alloys

The purpose of this study is to investigate the influence of samarium addition on the microstructures and mechanical properties of Al-5Cu alloys. The microstructures were examined by optical microscopy, X-ray diffraction, scanning electron microscopy, energy diffraction spectroscopy and differential thermal analysis. It was found that Sm was capable significantly of affecting the microstructures of Al-5Cu alloys. When 0.4 wt% Sm was added into the alloy, the aspect ratio and the mean area of Al2Cu phase were 10.9 and 61.0 grn：. They were decreased by 31.5% and 43.3% when compared with unmodified alloy. Meanwhile, a kind of nano size strengthening Al2Sm phase was formed in Al-5Cu alloys. In addition, the differential thermal analysis results showed that Sm addition results in a decrease in the melting temperature of ct-Al and Al2Cu. And a good combination of yield strength （244.5 MPa）, ultimate tensile strength （269.4 MPa） and elongation （6.9%） was obtained when the Sm addition was 0.4 wt%. Compared with unmodified Al-5Cu alloys, they were increased by 37.6%, 35.2% and 21.1%, respectively.

Plant Selection of Constructed Wetlands for Treatment of Piggery Wastewater

Piggery wastewater contains high concentrations of organic matter and ammonia nitrogen,and it is difficult to treat it and make the discharged wastewater to meet the standard. Since the treatment of piggery wastewater treated under anaerobic conditions by traditional aerobic methods requires large investment,high running expense and strict management,breeding enterprises could hardly accept the technique. According to the characteristics of piggery wastewater,Pennisetum sp. + Rumex acetosa Linn and Populus + Nerium oleander can be planted in constructed wetlands to treat piggery wastewater,which can improve the treatment effect of piggery wastewater by constructed wetlands,solve the difficulty of wastewater treatment in winter,and bring obvious economic benefit.

Fatigue characteristics of sand-cast AZ91D magnesium alloy

The fatigue characteristics of the AZ91D-T6 alloy samples taken from engine blocks have been investigated at 20℃ and elevated temperature(150℃).The fatigue strength and cyclic stress amplitude of the alloy significantly decrease with the increase of the test temperature,although cyclic hardening occurs continuously until failure for both temperatures.With the increase of the temperature,the decreased fatigue life of the alloy tested at the same stress amplitude is mainly attributed to the decreased matrix strength and the increased hysteresis energies.Fatigue failure of the engine blocks made of AZ91D-T6 alloy is mainly controlled by casting defects.For the defect-free specimens,the crack initiation behavior is determined by the single-slip(20℃)and by environment-assisted cyclic slip(150℃)during fatigue,respectively.The low-cycle fatigue lives of the alloy can be predicted using the Coffin-Manson relation and Basquin laws,the three-parameter equation and the energy-based concepts,while the high-cycle fatigue lives of the alloy fitted well with the developed long crack life model and MSF life models.

Discovery of a wild,genetically pure Chinese giant salamander creates new conservation opportunities

Effective conservation of threatened biota relies on accurate assessments and scientific guidance.As an unfortunate example,Chinese giant salamanders(Andrias,CGS)remain critically endangered in nature.Misguided conservation efforts,e.g.,commercial propagation and releasing of millions of likely non-indigenous or interspecific hybrids,have further compromised conservation initiatives.Limited information on wild populations of CGS poses a significant conservation challenge.Following 18-month long field monitoring,we now report the discovery of a wild population of CGS in a closed nature reserve in Jiangxi Province,China.Genomic assessments reveal its genetic distinctiveness and do not detect genetic admixture with other species.Based on morphological and molecular evidences,we describe this CGS as a new species Andrias jiangxiensis sp.nov.This is the only known species of CGS today with a genetically pure,reproducing,in situ population.This discovery emphasizes the important role that closed nature reserves play in protecting species,and the necessity of integrating long-term field monitoring and genetic assessments.It sets a new pathway for discovering and conserving endangered species,especially for those biotas that are similarly being extirpated by anthropogenic translocations and overexploitation.

A novel process of extraction and separation of RE and Mn from Panxi rare earth mud

A novel process to extract and separate rare earth (RE) and manganese (Mn) from Panxi rare earth mud was developed. The process involves roasting the mud at 480?℃ with NH 4Cl as chlorinating agent, and leaching the calcine with hot water to obtain a rare earth chloride solution. After the solution was further purified, HD(DIBM)P (P 507 ) was applied as extractant to separate RE and Mn. By seven stages of fractional extraction, the RECl 3 and MnCl 2 solutions with 99.8% purity were obtained. Finally, the purified RECl 3 and MnCl 2 solution were precipitated by NH 4HCO 3 to obtain a crystal RE 2(CO 3) 3 and MnCO 3 products respectively.

Calculation of Cu-rich part of Cu-Ni-Si phase diagram

The thermodynamic calculation of phase equilibria in the Cu-Ni-Si alloy system was carried out using the CALPHAD method. The calculations show that there are three two-phase areas and two three-phase areas in the Cu-rich parts of the isothermal section of the phase diagram at 300-600 ℃,and the three two-phase areas are FCC-A1(Cu-rich)+γ-Ni5Si2,FCC-A1(Cu-rich)+δ-Ni2Si and FCC-A1(Cu-rich)+ε-Ni3Si2,two three-phase areas are FCC-A1(Cu-rich)+γ-Ni5Si2+δ-Ni2Si and FCC-A1(Cu-rich)+δ-Ni2Si+ε-Ni3Si2. For this reason,an alloy located in the Cu-rich portion may precipitate γ-Ni5Si2,δ-Ni2Si or ε-Ni3Si2;the proportion of each phase depends on the alloy composition and aging temperature. The transmission electron microscope analysis of the Cu-3.2Ni-0.75Si alloy indicates that the precipitates are mainly δ-Ni2Si with only a few γ-Ni5Si2 phase particles,which agrees well with the thermodynamic calculations of phase equilibria.

Quantitative study on the tension-compression yield asymmetry of a Mg-3Al-1Zn alloy with bimodal texture components

This study demonstrates the yield asymmetry in Mg-3Al-1Zn alloy containing both ND-texture(c-axis//ND(Normal direction))and TD-texture(c-axis//TD(Transverse direction))in a quantitative view.The results showed that the yield asymmetry is strongly dependent on the distribution of bimodal texture components,on the basis of the successful establishment of the quantified relationship between pre-deformation parameters and texture components distribution.It’s meaningful for providing key reference to texture design.Mechanical behavior of bimodal textured Mg alloy under tension and compression was tested.CYS/TYS(compressive yield stress/tensile yield stress)equal to 1 is obtained,implying that the yield asymmetry is eliminated when two textures distribute at specific fractions.The corresponding mechanism for the texture-dependence of tension-compression yield asymmetry is revealed by the analysis of slip/twinning activities and a compound use of the activation stress difference of slip/twinning(ΔStress)and geometrical compatibility factor(m′)between neighboring grains.Balanced activity of{10■2}twinning and a quite similar boundary obstacle effect against slip/twinning transfer under tension and compression accounts for such good symmetry performance.