Faba bean （Vicia faba L.）, one of the most important legumes in the world, evolved different types of cultivars due to its partial cross-pollination. The development of simple sequence repeat （SSR） markers from ex...Faba bean （Vicia faba L.）, one of the most important legumes in the world, evolved different types of cultivars due to its partial cross-pollination. The development of simple sequence repeat （SSR） markers from expressed sequence tags （EST） provided a useful tool for investigation of its genetic diversity. The purpose of the present study was to investigate the genetic diversity of faba bean from China and Europe using EST-SSR markers. 5 031 faba bean ESTs from the NCBI database were downloaded and assembled into 1 148 unigenes. A total of 107 microsatellites in 96 unigenes were identified, indicating that merely 8.36% of sequences contained SSRs. The most abundant SSR within faba bean was tri-nucleotide repeat motif, and among all the tri-nucleotide repeats, the motif AAG/CTT was the most abundant type. Based on these results, 11 EST-SSR markers were used to assess the genetic diversity of 29 faba bean cultivars from China and Europe with two to three alleles per locus. The polymorphism information content value ranged from 0.0644 to 0.4278 with an average of 0.2919. Principal coordinate analysis （PCA） and phylogenetic clustering based on these 11 EST-SSR markers distinguished these cultivars into different groups. The results indicated that faba bean in China had a narrow genetic basis, and the additional sources of genetic cultivars/accessions should be introduced to enhance the genetic variability. The results of this study proved that the EST-SSR marker is very effective in evaluation of faba bean germplasm.展开更多
It is extremely difficult to introduce high-density nano twins during the solidification process of TiAl alloy.In this study,high-density nanotwins are inducted in the as-cast Ti48Al2Cr alloyed by adding Re element.Ph...It is extremely difficult to introduce high-density nano twins during the solidification process of TiAl alloy.In this study,high-density nanotwins are inducted in the as-cast Ti48Al2Cr alloyed by adding Re element.Phase transformation,morphology characteristics of nano twins,compressive and tensile proper-ties,and the related mechanisms have been studied.Results show that B2 phase enriched with Re tends to precipitate along theα_(2)/γinterface within lamellar colony.The stacking fault energy(SFE)ofγphase decreases from 43 mJ/m^(2) to 16 mJ/m^(2) as Re content increases from 0 at.%to 0.6 at.%,decreasing the crit-ical shear stress for twin formation.Compared to the mismatch value ofα_(2)/γinterface(0.004),which of B2/α_(2) and B2/γinterfaces increase to 0.247 and 0.149,respectively.Driven by high interfacial stress,high-density dislocations are generated at the B2/α_(2) interface,providing the dislocation slip channel for the formation of stacking faults(SFs)and nanotwins at the B2/γinterface.Therefore,the mechanism of inducting high-density nanotwins is to reduce the stacking fault energy ofγphase by Re and form highly mismatched B2/α_(2) interface.Compressive strength and the strain increase from 1723 MPa to 2398 MPa and 29%to 39%as Re content increases from 0 at.%to 0.6 at.%,respectively.Tensile strength increases from 356 MPa to 452 MPa without sacrificing plasticity.The improvement in strength and plasticity are attributed to the nano-twinning strengthening and interfacial thermal mismatch strengthening.Forming nanotwins during solidification process serve as the nucleation sites for newly formed twins during de-formation process,increasing the deformation tolerance of TiAl alloy.展开更多
The reclamation of tidal fiats has been one of the important approaches to replenish the arable lands in the coastal areas; pollution status of reclaimed soils has received wide attention recently, especially for the ...The reclamation of tidal fiats has been one of the important approaches to replenish the arable lands in the coastal areas; pollution status of reclaimed soils has received wide attention recently, especially for the study of heavy metals due to the relative high pollutant concentrations in wetlands. To understand the impact of land use change on heavy metal and arsenic （As） geochemistry by the reclamation of wetlands for agriculture, surface soils and soil profiles were collected from the agricultural land reclaimed in the 1990s and the intertidal flat wetland at Dongtan on Chongming Island in the Yangtze River Estuary, China. The soil samples were analyzed for total concentrations and chemical speciation of chromium （Cr）, zinc （Zn）, copper （Cu）, lead （Pb）, nickel （Ni）, cadmium （Cd） and As using inductively coupled plasma mass spectrometry （ICP-MS）. Results showed that soil properties （salinity, total organic carbon and grain-size distribution） and the concentrations of heavy metals and As in the soils differed under the different land use types. The conversion of wetland to forest had caused obvious losses of all the measured heavy metals. In paddy field and dryland with frequent cultivation, the concentrations of Cr, Zn, Cu, Ni and As were higher when compared to forest land which was disturbed rarely by human activities. Speciation analysis showed that Cr, Zn, Cu, Ni and As were predominated by the immobile residual fraction, while Pb and Cd showed relatively higher mobility. In general, metal （except Ni） and As mobility decreased in the following order： wetland 〉 dryland 〉 paddy field 〉 forest land, which suggested that the reclaimed soils had lower metal and As mobility than the intertidal fiat wetland. The results of this study contribute to a better understanding of the effects of land use on heavy metals and As in the reclaimed soils of the study area and other similar coastal areas.展开更多
The development of expressed sequence tag-derived simple sequence repeats(EST-SSRs) provided a useful tool for investigating plant genetic diversity.In the present study,22 polymorphic EST-SSRs from grain soybean were...The development of expressed sequence tag-derived simple sequence repeats(EST-SSRs) provided a useful tool for investigating plant genetic diversity.In the present study,22 polymorphic EST-SSRs from grain soybean were identified and used to assess the genetic diversity in 48 vegetable soybean accessions.Among the 22 EST-SSR loci,tri-nucleotides were the most abundant repeats,accounting for 50.00% of the total motifs.GAA was the most common motif among tri-nucleotide repeats,with a frequency of 18.18%.Polymorphic analysis identified a total of 71 alleles,with an average of 3.23 per locus.The polymorphism information content(PIC) values ranged from 0.144 to 0.630,with a mean of 0.386.Observed heterozygosity(H o) values varied from 0.0196 to 1.0000,with an average of 0.6092,while the expected heterozygosity(H e) values ranged from 0.1502 to 0.6840,with a mean value of 0.4616.Principal coordinate analysis and phylogenetic tree analysis indicated that the accessions could be assigned to different groups based to a large extent on their geographic distribution,and most accessions from China were clustered into the same groups.These results suggest that Chinese vegetable soybean accessions have a narrow genetic base.The results of this study indicate that EST-SSRs from grain soybean have high transferability to vegetable soybean,and that these new markers would be helpful in taxonomy,molecular breeding,and comparative mapping studies of vegetable soybean in the future.展开更多
A new upconversion luminescence agent, 40CdF2·60BaF2·0.8ErO3, was synthesized and its fluorescent spectra were determined. This upconversion luminescence agent can emit five upconversion fluorescent peaks sh...A new upconversion luminescence agent, 40CdF2·60BaF2·0.8ErO3, was synthesized and its fluorescent spectra were determined. This upconversion luminescence agent can emit five upconversion fluorescent peaks shown in the fluorescent spectra whose wavelengths are all below 387 nm under the excitation of 488 nm visible light. This upconversion luminescence agent was mixed into nano rutile TiO2 powder by ultrasonic and boiling dispersion and the novel doped nano TiO2 photocatalyst utilizing visible light was firstly prepared. The doped TiO2 powder was charactered by XRD and TEM and its photocatalytic activity was tested through the photocatalytic degradation of methyl orange as a model compound under the visible light irradiation emitted by six three basic color lamps. In order to compare the photocatalytic activities, the same experiment was carried out for undoped TiO2 powder. The degradation ratio of methyl orange in the presence of doped nano TiO2 powder reached 32.5% under visible light irradiation at 20 h which was obviously higher than the corresponding 1.64% in the presence of undoped nano TiO2 powder, which indicate the upconversion luminescence agent prepared as dopant can effectively turn visible lights to ultraviolet lights that are absorbed by nano TiO2 particles to produce the electron-cavity pairs. All the results show that the nano rutile TiO2 powder doped with upconversion luminescence agent is a promising photocatalyst using sunlight for treating the industry dye wastewater in great force.展开更多
The quench sensitivity and their influential factors of 7,021, 7,085, and 7,050 alloys were investigated by the end quenching test method and the measurement of electrical conductivity, hardness, and microstructure af...The quench sensitivity and their influential factors of 7,021, 7,085, and 7,050 alloys were investigated by the end quenching test method and the measurement of electrical conductivity, hardness, and microstructure after aging. The results indicate that 7,050 alloy has the largest changes with hardness decreasing from HV 199 to HV 167,and electrical conductivity increases from 16.6 to18.2 MS m-1when the distance from quenched end increases from 2 to 100 mm. Alloys 7,085 and 7,021 have relatively smaller changes. According to the relationship between the hardness and electrical conductivity of a supersaturated solid solution, 7,050 alloy has higher quench sensitivity than 7,085 and 7,021 alloys. The microstructure of 7,050 alloy with higher major alloy element（Zn ？ Mg ？ Cu） addition and Cu element addition is mostly affected by the changes of distance from quenched end. In 7,050 alloy, the size of intragranular precipitates is from about 10-200 nm, and the（sub） grain boundary precipitates are about 20-300 nm. Alloy 7,085 with lower Cu content is moderately affected, while 7,021 is least affected. It is found that with the increase of distance from quenched end, quenched-induced precipitate preferentially nucleates and grows in the（sub） grain boundary and then on the pre-existing Al3 Zr particles.展开更多
Fertilizer plays an important role in increasing rice yield. More than half of all fertilizer applied to the field is not taken up, resulting in environmental damage and substantial economic losses. To address these c...Fertilizer plays an important role in increasing rice yield. More than half of all fertilizer applied to the field is not taken up, resulting in environmental damage and substantial economic losses. To address these concerns, a low-cost, coated compound fertilizer named "Xiang Nong Da"(XND), requiring only a single basal application, was studied. A two-year field experiment was conducted to test the effects of XND application on rice yield and nitrogen fertilizer use efficiency. An ordinary uncoated compound fertilizer(UNCF), with 20% more nutrients and split application was selected as the control. The yield of XND-treated rice was only 3.1% lower than that of the control, an insignificant difference. There were no significant differences between N use efficiency indices of the two fertilizer treatments except for N partial factor productivity(PFP_N). PFP_Nof XND treatment was 19.7%–23.2% higher than the control, a significant difference. This result indicates that a 20% decrease in N application rate is possible with XND without yield reduction and with savings in both labor and time.展开更多
A Co-free as-cast AlCrAlCrFe_(2)Ni_(2)medium entropy alloy(MEA)with multi-phases was remelted by fiber laser in this study.The effect of laser remelting on the microstructure,phase distribution and mechanical properti...A Co-free as-cast AlCrAlCrFe_(2)Ni_(2)medium entropy alloy(MEA)with multi-phases was remelted by fiber laser in this study.The effect of laser remelting on the microstructure,phase distribution and mechanical properties was investigated by characterizing the as-cast and the remelted AlCrAlCrFe_(2)Ni_(2)alloy.The laser remelting process resulted in a significant decrease of grain size from about 780μm to 58.89μm(longitudinal section)and 15.87μm(transverse section)and an increase of hardness from 4.72±0.293 GPa to 6.40±0.147 GPa(longitudinal section)and 7.55±0.360 GPa(transverse section).It was also found that the long side plate-like microstructure composed of FCC phase,ordered B2 phase and disordered BCC phase in the as-cast alloy was transformed into nano-size weave-like microstructure consisting of alternating ordered B2 and disordered BCC phases.The mechanical properties were evaluated by the derived stressstrain relationship obtained from nano-indentation tests data.The results showed that the yield stress increased from 661.9 MPa to 1347.6 MPa(longitudinal section)and 1647.2 MPa(transverse section)after remelting.The individual contribution of four potential strengthening mechanisms to the yield strength of the remelted alloy was quantitatively evaluated,including grain boundary strengthening,dislocation strengthening,solid solution strengthening and precipitation strengthening.The calculation results indicated that dislocation and precipitation are dominant strengthening mechanisms in the laser remelted MEA.展开更多
The distribution, morphologies and structures of intergranular Nd-rich phase in sintered Nd-Fe-B magnets were studied through electron microscopy. Backscattered electron （BSE） imaging revealed that Nd-rich particles...The distribution, morphologies and structures of intergranular Nd-rich phase in sintered Nd-Fe-B magnets were studied through electron microscopy. Backscattered electron （BSE） imaging revealed that Nd-rich particles with various morphologies and sizes were randomly distributed at the grain boundaries and the triple junctions of the tetragonal Nd2FelnB matrix. Through selected area electron diffraction （SAED） analysis under a systematic tilting condition, most intergranular Nd-rich phase particles, with sizes ranging from hundreds of nanometres to several micrometres, were identified as face-centred cubic （FCC） structure. Such particles possessed several approximate orientation relationships with their adjacent Nd2FelaB matrix grains, such as （002）Nd2Fe14B/ （200）FCC_Nd-rieh [120] Nd2Fe14B//[001]FCC Nd-fich, （002）Nd2Fe14B//（220）FCC_Nd-rich [110] Nd2Fe14B//[l12]FCC_Nd-rich, as well as （011）Nd2Fe14B// （13 1 ）rcc Nd-rich [111 ] Nd2Fe14B//[ 114]FCC Nd_rich, which could be attributed to minimising interracial energy. The combination of high- resolution electron microscopy with energy-dispersive X-ray spectroscopy revealed the internal inhomogeneous nature of Nd-rich phases. The large lattice distortion and nanoscale-ordered structures within a single Nd2rich grain were observed.展开更多
The ICP-AES method for the determination of Ge in GdSiGe series alloys was studied.As the three main elements in the alloys,Gd,Si,and Ge differ greatly from each other in chemical properties,it was difficult to pretre...The ICP-AES method for the determination of Ge in GdSiGe series alloys was studied.As the three main elements in the alloys,Gd,Si,and Ge differ greatly from each other in chemical properties,it was difficult to pretreat the sample.Two decomposition methods were compared,and a mixture of HNO3＋HF was used to decompose the sample and the effect of the HF amount on the sample decomposition was examined.The adsorption effect of GdF3 on Ge was discussed.Three GdSiGe series alloy samples were analyzed,and the RSDs of this method were in the range of 0.85%～2.66%.展开更多
Magnesium cylindrical parts have relatively poor mechanical properties and distinct anisotropy of microstructure,which hinder their application as structural components.To improve the performance of WE71 cylindrical p...Magnesium cylindrical parts have relatively poor mechanical properties and distinct anisotropy of microstructure,which hinder their application as structural components.To improve the performance of WE71 cylindrical parts,multi-direction forging(MDF)was introduced before back extrusion,and the microstructure and mechanical properties were investigated.Results of microstructure show that the grain size in the outer of the cylindrical bottom is refined from 30.1 to 27.7μm,the micro structure is more uniform and the dislocation density is higher.The bimodal grain structure is formed in the outer of the cylindrical wall,which is ascribed to the formation of MgsRE phases along grain boundaries.These phases result in the Zener pinning effect on grain boundaries and the reduction of DRX volume fraction.The texture type of the cylindrical bottom is<0001>‖ED and the cylindrical wall is<1010>‖ED,and the maximum pole intensity is 1.986 and 1.664,respectively.Results of the tensile test at room temperature show that combined improved strength and ductility of the cylindrical part is attained after introducing the MDF process.The ultimate tensile strength(UTS),yield strength(YS)and elongation are279 MPa,185 MPa and 12%at the bottom and 299 MPa,212 MPa and 20%at the wall.展开更多
The microstructures and strengthening mechanisms of the Mg-8.2 Gd-4.6 Y-1.5 Zn-0.4 Zr(wt%) alloy with long-period stacking ordered(LPSO),β’ and γ type phases were systematically studied.The results show that the LP...The microstructures and strengthening mechanisms of the Mg-8.2 Gd-4.6 Y-1.5 Zn-0.4 Zr(wt%) alloy with long-period stacking ordered(LPSO),β’ and γ type phases were systematically studied.The results show that the LPSO with lamellar and block structures forms near the grain boundaries.The grains are clearly refined,and the 18 R LPSO phase is oriented along the extrusion direction after extrusion.Some particles also precipitate from the Mg matrix dynamically.The extruded alloy exhibits a remarkable agehardening response,and mechanical properties,with a tensile strength(TS) of 449 MPa,yield strength(YS) of 362 MPa,and elongation of 7.9% obtained in the peak-aged alloy.The strengthening mechanisms of the alloy in different states are discussed.Grain boundary and precipitation strengthening are the main strengthening mechanisms for the peak-aged alloy.展开更多
Polyamines play important roles in plant tolerance to environmental stress. With the aim of investigating the possible involvement of putrescine （Put） in salt-tolerance mechanisms in vegetable soybean roots, exogeno...Polyamines play important roles in plant tolerance to environmental stress. With the aim of investigating the possible involvement of putrescine （Put） in salt-tolerance mechanisms in vegetable soybean roots, exogenous Put （10 mmol L＂） and its biosynthetic inhibitor D-arginine （D-Arg） （0.5 mmol L-1） were added to nutrient solution when vegetable soybean （Glycine max L. cv. Huning 95-1） seedlings were exposed to 100 mmol L^-11 sodium chloride （NaCl）. The results showed that Put ameliorated but D-Arg aggravated the detrimental effects of NaCl on plant growth and biomass production. Under NaCl stress, levels of free, soluble conjugated and insoluble bound types of Put in roots of vegetable soybean were reduced, whereas those of free, soluble conjugated, and insoluble bound types of spermidine （Spd） and spermine （Spm） were increased. Exogenous Put eliminated the decrease in Put but promoted the increase of Spd and Spm. However, these changes could be reversed by D-Arg. Under NaCl stress, activities of arginine decarboxylase （ADC）, S-adenosylmethionine decarboxylase （SAMDC）, diamine oxidase （DAO）, and polyamine oxidase （PAO） were induced, with exogenous Put promoting and D-Arg reversing these changes. Furthermore, NaCl stress decreased activities of antioxidant enzymes. Exogenous Put alleviated but D-Arg exaggerated these effects of NaCl stress, resulting in the same changes in membrane damage and reactive oxygen species （ROS） production. These results indicated that Put plays a positive role in vegetable soybean roots by activating antioxidant enzymes and thereby attenuating oxidative damage.展开更多
The effects of minor Zn(0.2 at%,0.4 at%,0.6 at%) on the microstructures and mechanical properties of Mg-1.4 Gd-1.2 Y-0.15 Zr(at%) alloys were systematically explored.Results reveal that increasing Zn content leads to ...The effects of minor Zn(0.2 at%,0.4 at%,0.6 at%) on the microstructures and mechanical properties of Mg-1.4 Gd-1.2 Y-0.15 Zr(at%) alloys were systematically explored.Results reveal that increasing Zn content leads to the increase of the intergranular phases and the change of their composition from Mg24(Gd,Y)5 phase and(Mg,Zn)3(Gd,Y) phase to 18 R-LPSO phase and(Mg,Zn)3(Gd,Y) phase.Mg24(Gd,Y)5 phase is body-centered cubic structure and shares the same lattice constant with Mg24Y5 while(Mg,Zn)3(Gd,Y)phase is face-centered cubic structure with lattice constant of 0.72 nm,slightly lower than Mg3Gd.18RLPSO structure is identified to be monoclinic with c-axis not strictly vertical to the bottom surface but93.5°.The growth patterns of intergranular phases change from the divorced growth to coupled growth as compositions change.Moreover,the mechanical performance improves with Zn rising,ascribed to the decrease of brittle phases at grain boundaries and the increase of LPSO structure phases.展开更多
Silicon has been investigated extensively as a promising anode material for rechargeable lithium-ion bat- teries. Understanding the failure mechanism of silicon-based anode electrodes for lithium-ion batteries is esse...Silicon has been investigated extensively as a promising anode material for rechargeable lithium-ion bat- teries. Understanding the failure mechanism of silicon-based anode electrodes for lithium-ion batteries is essential to solve the problem of low coulombic efficiency and capacity fading on cycling and also to further commercialize this very new energetic material in cells. To reach this goal, the structure changes of bulk silicon particles and electrode after cycling were studied using ex-situ scanning electron microscopy （SEM） and X-ray diffraction （XRD） techniques. The SEM images indicated that the microstructural changes of the bulk silicon particles during cycling led to a layer rupture of the electrode and then the breakdown of the conductive network and the failure of the electrode. The result contributes to the basic understanding of the failure mechanism of a bulk sil- icon anode electrode for lithium-ion batteries.展开更多
A highly effective phase transfer of a quaternary ammonium gemini surfactant with ester groups（（diethylhexanedioate） diyl-a,v-bis（dimethyl dodecyl ammonium bromide） referred to as 12-10-12）was synthesized with h...A highly effective phase transfer of a quaternary ammonium gemini surfactant with ester groups（（diethylhexanedioate） diyl-a,v-bis（dimethyl dodecyl ammonium bromide） referred to as 12-10-12）was synthesized with high yield and characterized by infrared spectroscopy, elemental analysis and1 HNMR. Then, 12-10-12 was used as a phase transfer catalyst to study the catalytic effect on the reaction of anhydrous sodium acetate and 4-methylbenzyl chloride. The possible catalytic mechanism and the influence of surfactant concentration, temperature and type are also discussed. The experimental results showed that the catalysis efficiency was more active than the traditional, single-chained surfactant,tetrabutyl ammonium bromide. It also revealed that the reaction was first-order with respect to the concentration of 4-methylbenzyl chloride. The concentration of 4-methylbenzyl chloride grew linearly with the concentration of 12-10-12 and as the reaction temperature increased. The optimum reaction time was 7 h.展开更多
OBJECTIVE： To investigate, in terms of Notch signaling pathway, the effect on pancreatic cancer of the extract of an anti-tumor prescription -- Qingyihuaji formula （QYHJ） -- from Traditional Chinese Medicine （TCM...OBJECTIVE： To investigate, in terms of Notch signaling pathway, the effect on pancreatic cancer of the extract of an anti-tumor prescription -- Qingyihuaji formula （QYHJ） -- from Traditional Chinese Medicine （TCM）.METHODS： Nude mice were implanted subcutaneously with human pancreatic cancer cell line SW1990 and then randomly divided into four groups： Control, QYHJ extract, Gemcitabine, and Combination of QYHJ extract and gemcitabine. Treatments were given for 21 days and tumor growth was evaluated simultaneously. Then, expression of Notch receptors （Notch-I, Notch-2, Notch-3, and Notch-4） and their Jagged ligands （Jagged-1 and Jagged-2） in dissected tumor tissue were detected by real-time quantitative reverse transcription-polymerase chain reaction and Western blot. Finally, immunohistochemistry was performed to detect CD133, a marker of pancreatic cancer stem cells （CSCs）, to evaluate the impact of QYHJ extract on pancreatic CSCs.RESULTS： QYHJ extract treatment effectively inhib- ited the tumor growth in nude mice. The expression of both Notch-4 and Jagged-1 were decreased significantly in QYHJ treatment groups （P 〈 0.05）, while gemcitabine alone had no significant effect in down-regulating Jagged-1 （P 〉 0.05）. No significant difference was observed in the ex- pression of Notch-1, Notch-2, Notch-3, and Jagged-2 between three treatment groups and control group （P 〉 0.05）. Moreover, immunohistochemical analysis showed that the number of CD133 positive cells was significantly reduced by QYHJ treatment （P 〈 0.05）, and the combined treatment was more effective than gemcitabine alone （P 〈 0.05）.CONCLUSION： The role of the extract in pancreatic cancer treatment was associated with down-regulation of Notch-4 and Jagged-1 in Notch signaling pathway. The extract could enhance the antitumor activity of gemcitabine and was more effective than gemcitabine in regulating Notch signaling pathway to some extent.展开更多
Based on the industrial production of non-oriented silicon steel,calcium treatment by CaSi wire feeding during the RH refining process was studied. The thermodynamics of CaS inclusion formation was analyzed, and the m...Based on the industrial production of non-oriented silicon steel,calcium treatment by CaSi wire feeding during the RH refining process was studied. The thermodynamics of CaS inclusion formation was analyzed, and the morphology and the size distribution were observed. Furthermore, the change in inclusion characteristics after calcium treatment and the effect of calcium treatment on magnetic properties were discussed. The results show that the formation of MnS and A1N inclusions were restrained, and the aggregating, floating and removing of microinclusions after calcium treatment were effectively promoted. The cleanliness of liquid steel was obviously increased. The main type of inclusions was single phase of CaO, with some complex inclusions composed of CaO, SiO2 and MgO. No CaS inclusion was observed after an appropriate calcium treatment. The size of all inclusions was distributed in the range of 2 - 20 μm, and the number was about 1.8 × 10^5/mm3. In addition, as an increasing amount of calcium was added,the core loss gradually decreased to a stable level, and the magnetic induction decreased quickly after a slow increase. The optimal calcium treatment mode depends on the chemical composition of steel.展开更多
Compound ceramic coatings with the main crystalline of Al_2TiO_5（in the as-prepared coating without treatment） were prepared in situ on the surface Ti-6Al-4V alloy by means of pulsed bipolar micro-arc oxidation in N...Compound ceramic coatings with the main crystalline of Al_2TiO_5（in the as-prepared coating without treatment） were prepared in situ on the surface Ti-6Al-4V alloy by means of pulsed bipolar micro-arc oxidation in Na AlO_2 solution. For the purpose of studying the antioxidation properties of the samples, the coated samples treated in argon and the as-coated samples were calcined in air at 1000 °C. And the related characteristics were investigated by X-ray diffraction（XRD）, scanning electron microscopy（SEM） and X-ray fluorescence（XRF） spectroscopy, respectively. The results show that, when it was calcined in air for 1 h, Al_2TiO_5in the as-prepared coating decomposed and transformed into α-Al_2O_3 and rutile TiO_2.However, after almost 4 h in argon, Al_2TiO_5in the asprepared coating decomposed and the final coating surface contents are completely α-Al_2O_3, and those of the middle interface are mainly Al_2O_3 and Ti_2O_3. The morphologies of the coatings after calcination in argon and air are different.High-temperature oxidation occurred violently in the alloy substrate without coatings. Furthermore, the weight gain curves of the as-prepared samples and the coated samples treated in argon both show a parabolic shape.展开更多
High temperature deformation behavior and workability of Mg-8.1 Gd-4.5Y-0.3Zr alloy were studied by compression tests.Arrhenius equation with strain compensation and processing maps were established.The results show t...High temperature deformation behavior and workability of Mg-8.1 Gd-4.5Y-0.3Zr alloy were studied by compression tests.Arrhenius equation with strain compensation and processing maps were established.The results show that the activation energy Q,structure factor a,n and In A varies with the strain,its relationship fit well by fifth order polynomial.The flow stresses predicted by the extracted model are in good agreement with the experimental results.There are five typical domains in the processing map,and the deformation mechanisms in different domains were determined by microstructure analysis.The feasible processing window of the alloy is in the areas of 400-500℃/0.001-0.1 s^(-1).展开更多
基金supported by the Zhejiang Provincial Science and Technology Program, China (2007C32013)the Natural Science Foundation of Zhejiang Province, China (Y3090660)
文摘Faba bean （Vicia faba L.）, one of the most important legumes in the world, evolved different types of cultivars due to its partial cross-pollination. The development of simple sequence repeat （SSR） markers from expressed sequence tags （EST） provided a useful tool for investigation of its genetic diversity. The purpose of the present study was to investigate the genetic diversity of faba bean from China and Europe using EST-SSR markers. 5 031 faba bean ESTs from the NCBI database were downloaded and assembled into 1 148 unigenes. A total of 107 microsatellites in 96 unigenes were identified, indicating that merely 8.36% of sequences contained SSRs. The most abundant SSR within faba bean was tri-nucleotide repeat motif, and among all the tri-nucleotide repeats, the motif AAG/CTT was the most abundant type. Based on these results, 11 EST-SSR markers were used to assess the genetic diversity of 29 faba bean cultivars from China and Europe with two to three alleles per locus. The polymorphism information content value ranged from 0.0644 to 0.4278 with an average of 0.2919. Principal coordinate analysis （PCA） and phylogenetic clustering based on these 11 EST-SSR markers distinguished these cultivars into different groups. The results indicated that faba bean in China had a narrow genetic basis, and the additional sources of genetic cultivars/accessions should be introduced to enhance the genetic variability. The results of this study proved that the EST-SSR marker is very effective in evaluation of faba bean germplasm.
基金supported by the National Natural Science Foundation of China(No.U21A2042)the National Nature Fund Youth Fund Project of China(No.52101038)Young Elite Scientists Sponsorship Program by CAST(No.2021QNRC001).
文摘It is extremely difficult to introduce high-density nano twins during the solidification process of TiAl alloy.In this study,high-density nanotwins are inducted in the as-cast Ti48Al2Cr alloyed by adding Re element.Phase transformation,morphology characteristics of nano twins,compressive and tensile proper-ties,and the related mechanisms have been studied.Results show that B2 phase enriched with Re tends to precipitate along theα_(2)/γinterface within lamellar colony.The stacking fault energy(SFE)ofγphase decreases from 43 mJ/m^(2) to 16 mJ/m^(2) as Re content increases from 0 at.%to 0.6 at.%,decreasing the crit-ical shear stress for twin formation.Compared to the mismatch value ofα_(2)/γinterface(0.004),which of B2/α_(2) and B2/γinterfaces increase to 0.247 and 0.149,respectively.Driven by high interfacial stress,high-density dislocations are generated at the B2/α_(2) interface,providing the dislocation slip channel for the formation of stacking faults(SFs)and nanotwins at the B2/γinterface.Therefore,the mechanism of inducting high-density nanotwins is to reduce the stacking fault energy ofγphase by Re and form highly mismatched B2/α_(2) interface.Compressive strength and the strain increase from 1723 MPa to 2398 MPa and 29%to 39%as Re content increases from 0 at.%to 0.6 at.%,respectively.Tensile strength increases from 356 MPa to 452 MPa without sacrificing plasticity.The improvement in strength and plasticity are attributed to the nano-twinning strengthening and interfacial thermal mismatch strengthening.Forming nanotwins during solidification process serve as the nucleation sites for newly formed twins during de-formation process,increasing the deformation tolerance of TiAl alloy.
基金supported by the National Natural Science Foundation of China (Nos. 41271466 and 40871216)
文摘The reclamation of tidal fiats has been one of the important approaches to replenish the arable lands in the coastal areas; pollution status of reclaimed soils has received wide attention recently, especially for the study of heavy metals due to the relative high pollutant concentrations in wetlands. To understand the impact of land use change on heavy metal and arsenic （As） geochemistry by the reclamation of wetlands for agriculture, surface soils and soil profiles were collected from the agricultural land reclaimed in the 1990s and the intertidal flat wetland at Dongtan on Chongming Island in the Yangtze River Estuary, China. The soil samples were analyzed for total concentrations and chemical speciation of chromium （Cr）, zinc （Zn）, copper （Cu）, lead （Pb）, nickel （Ni）, cadmium （Cd） and As using inductively coupled plasma mass spectrometry （ICP-MS）. Results showed that soil properties （salinity, total organic carbon and grain-size distribution） and the concentrations of heavy metals and As in the soils differed under the different land use types. The conversion of wetland to forest had caused obvious losses of all the measured heavy metals. In paddy field and dryland with frequent cultivation, the concentrations of Cr, Zn, Cu, Ni and As were higher when compared to forest land which was disturbed rarely by human activities. Speciation analysis showed that Cr, Zn, Cu, Ni and As were predominated by the immobile residual fraction, while Pb and Cd showed relatively higher mobility. In general, metal （except Ni） and As mobility decreased in the following order： wetland 〉 dryland 〉 paddy field 〉 forest land, which suggested that the reclaimed soils had lower metal and As mobility than the intertidal fiat wetland. The results of this study contribute to a better understanding of the effects of land use on heavy metals and As in the reclaimed soils of the study area and other similar coastal areas.
基金Project supported by the National Natural Science Foundation of China(Nos.31101538,31000942,and 31000676)the Grand Science and Technology Special Project of Zhejiang Province(Nos.2010 C02006,2012C12903-4-1,and 2012C12903-6-3)+2 种基金the Zhejiang Provincial Natural Science Foundation of China(No.LY12C15004)the Public Welfare Project of Zhejiang Province(No.2011C22011)the Shaoxing Important Science and Technology Projects (No.2012A22008),China
文摘The development of expressed sequence tag-derived simple sequence repeats(EST-SSRs) provided a useful tool for investigating plant genetic diversity.In the present study,22 polymorphic EST-SSRs from grain soybean were identified and used to assess the genetic diversity in 48 vegetable soybean accessions.Among the 22 EST-SSR loci,tri-nucleotides were the most abundant repeats,accounting for 50.00% of the total motifs.GAA was the most common motif among tri-nucleotide repeats,with a frequency of 18.18%.Polymorphic analysis identified a total of 71 alleles,with an average of 3.23 per locus.The polymorphism information content(PIC) values ranged from 0.144 to 0.630,with a mean of 0.386.Observed heterozygosity(H o) values varied from 0.0196 to 1.0000,with an average of 0.6092,while the expected heterozygosity(H e) values ranged from 0.1502 to 0.6840,with a mean value of 0.4616.Principal coordinate analysis and phylogenetic tree analysis indicated that the accessions could be assigned to different groups based to a large extent on their geographic distribution,and most accessions from China were clustered into the same groups.These results suggest that Chinese vegetable soybean accessions have a narrow genetic base.The results of this study indicate that EST-SSRs from grain soybean have high transferability to vegetable soybean,and that these new markers would be helpful in taxonomy,molecular breeding,and comparative mapping studies of vegetable soybean in the future.
基金The National Natural Science Foundation of China (No.20371023)
文摘A new upconversion luminescence agent, 40CdF2·60BaF2·0.8ErO3, was synthesized and its fluorescent spectra were determined. This upconversion luminescence agent can emit five upconversion fluorescent peaks shown in the fluorescent spectra whose wavelengths are all below 387 nm under the excitation of 488 nm visible light. This upconversion luminescence agent was mixed into nano rutile TiO2 powder by ultrasonic and boiling dispersion and the novel doped nano TiO2 photocatalyst utilizing visible light was firstly prepared. The doped TiO2 powder was charactered by XRD and TEM and its photocatalytic activity was tested through the photocatalytic degradation of methyl orange as a model compound under the visible light irradiation emitted by six three basic color lamps. In order to compare the photocatalytic activities, the same experiment was carried out for undoped TiO2 powder. The degradation ratio of methyl orange in the presence of doped nano TiO2 powder reached 32.5% under visible light irradiation at 20 h which was obviously higher than the corresponding 1.64% in the presence of undoped nano TiO2 powder, which indicate the upconversion luminescence agent prepared as dopant can effectively turn visible lights to ultraviolet lights that are absorbed by nano TiO2 particles to produce the electron-cavity pairs. All the results show that the nano rutile TiO2 powder doped with upconversion luminescence agent is a promising photocatalyst using sunlight for treating the industry dye wastewater in great force.
基金financially supported by the National Natural Science Foundation of China (No. 51274046)
文摘The quench sensitivity and their influential factors of 7,021, 7,085, and 7,050 alloys were investigated by the end quenching test method and the measurement of electrical conductivity, hardness, and microstructure after aging. The results indicate that 7,050 alloy has the largest changes with hardness decreasing from HV 199 to HV 167,and electrical conductivity increases from 16.6 to18.2 MS m-1when the distance from quenched end increases from 2 to 100 mm. Alloys 7,085 and 7,021 have relatively smaller changes. According to the relationship between the hardness and electrical conductivity of a supersaturated solid solution, 7,050 alloy has higher quench sensitivity than 7,085 and 7,021 alloys. The microstructure of 7,050 alloy with higher major alloy element（Zn ？ Mg ？ Cu） addition and Cu element addition is mostly affected by the changes of distance from quenched end. In 7,050 alloy, the size of intragranular precipitates is from about 10-200 nm, and the（sub） grain boundary precipitates are about 20-300 nm. Alloy 7,085 with lower Cu content is moderately affected, while 7,021 is least affected. It is found that with the increase of distance from quenched end, quenched-induced precipitate preferentially nucleates and grows in the（sub） grain boundary and then on the pre-existing Al3 Zr particles.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest(201303103)China Agriculture Research System(CARS-01)
文摘Fertilizer plays an important role in increasing rice yield. More than half of all fertilizer applied to the field is not taken up, resulting in environmental damage and substantial economic losses. To address these concerns, a low-cost, coated compound fertilizer named "Xiang Nong Da"(XND), requiring only a single basal application, was studied. A two-year field experiment was conducted to test the effects of XND application on rice yield and nitrogen fertilizer use efficiency. An ordinary uncoated compound fertilizer(UNCF), with 20% more nutrients and split application was selected as the control. The yield of XND-treated rice was only 3.1% lower than that of the control, an insignificant difference. There were no significant differences between N use efficiency indices of the two fertilizer treatments except for N partial factor productivity(PFP_N). PFP_Nof XND treatment was 19.7%–23.2% higher than the control, a significant difference. This result indicates that a 20% decrease in N application rate is possible with XND without yield reduction and with savings in both labor and time.
文摘A Co-free as-cast AlCrAlCrFe_(2)Ni_(2)medium entropy alloy(MEA)with multi-phases was remelted by fiber laser in this study.The effect of laser remelting on the microstructure,phase distribution and mechanical properties was investigated by characterizing the as-cast and the remelted AlCrAlCrFe_(2)Ni_(2)alloy.The laser remelting process resulted in a significant decrease of grain size from about 780μm to 58.89μm(longitudinal section)and 15.87μm(transverse section)and an increase of hardness from 4.72±0.293 GPa to 6.40±0.147 GPa(longitudinal section)and 7.55±0.360 GPa(transverse section).It was also found that the long side plate-like microstructure composed of FCC phase,ordered B2 phase and disordered BCC phase in the as-cast alloy was transformed into nano-size weave-like microstructure consisting of alternating ordered B2 and disordered BCC phases.The mechanical properties were evaluated by the derived stressstrain relationship obtained from nano-indentation tests data.The results showed that the yield stress increased from 661.9 MPa to 1347.6 MPa(longitudinal section)and 1647.2 MPa(transverse section)after remelting.The individual contribution of four potential strengthening mechanisms to the yield strength of the remelted alloy was quantitatively evaluated,including grain boundary strengthening,dislocation strengthening,solid solution strengthening and precipitation strengthening.The calculation results indicated that dislocation and precipitation are dominant strengthening mechanisms in the laser remelted MEA.
基金Foundation item： Project supported by the Chinese Ministry of Science and Technology （2012IM030500） and National Natural Science Foundation of China （51201015, 51271038, 51171048）
文摘The distribution, morphologies and structures of intergranular Nd-rich phase in sintered Nd-Fe-B magnets were studied through electron microscopy. Backscattered electron （BSE） imaging revealed that Nd-rich particles with various morphologies and sizes were randomly distributed at the grain boundaries and the triple junctions of the tetragonal Nd2FelnB matrix. Through selected area electron diffraction （SAED） analysis under a systematic tilting condition, most intergranular Nd-rich phase particles, with sizes ranging from hundreds of nanometres to several micrometres, were identified as face-centred cubic （FCC） structure. Such particles possessed several approximate orientation relationships with their adjacent Nd2FelaB matrix grains, such as （002）Nd2Fe14B/ （200）FCC_Nd-rieh [120] Nd2Fe14B//[001]FCC Nd-fich, （002）Nd2Fe14B//（220）FCC_Nd-rich [110] Nd2Fe14B//[l12]FCC_Nd-rich, as well as （011）Nd2Fe14B// （13 1 ）rcc Nd-rich [111 ] Nd2Fe14B//[ 114]FCC Nd_rich, which could be attributed to minimising interracial energy. The combination of high- resolution electron microscopy with energy-dispersive X-ray spectroscopy revealed the internal inhomogeneous nature of Nd-rich phases. The large lattice distortion and nanoscale-ordered structures within a single Nd2rich grain were observed.
基金Project supported by the New Technology and New Method Item of Ministry of Science and Technology of PRC(2005JG200030)
文摘The ICP-AES method for the determination of Ge in GdSiGe series alloys was studied.As the three main elements in the alloys,Gd,Si,and Ge differ greatly from each other in chemical properties,it was difficult to pretreat the sample.Two decomposition methods were compared,and a mixture of HNO3＋HF was used to decompose the sample and the effect of the HF amount on the sample decomposition was examined.The adsorption effect of GdF3 on Ge was discussed.Three GdSiGe series alloy samples were analyzed,and the RSDs of this method were in the range of 0.85%～2.66%.
基金Project supported by the General Program of National Natural Science Foundation of China(51871195,51501015)。
文摘Magnesium cylindrical parts have relatively poor mechanical properties and distinct anisotropy of microstructure,which hinder their application as structural components.To improve the performance of WE71 cylindrical parts,multi-direction forging(MDF)was introduced before back extrusion,and the microstructure and mechanical properties were investigated.Results of microstructure show that the grain size in the outer of the cylindrical bottom is refined from 30.1 to 27.7μm,the micro structure is more uniform and the dislocation density is higher.The bimodal grain structure is formed in the outer of the cylindrical wall,which is ascribed to the formation of MgsRE phases along grain boundaries.These phases result in the Zener pinning effect on grain boundaries and the reduction of DRX volume fraction.The texture type of the cylindrical bottom is<0001>‖ED and the cylindrical wall is<1010>‖ED,and the maximum pole intensity is 1.986 and 1.664,respectively.Results of the tensile test at room temperature show that combined improved strength and ductility of the cylindrical part is attained after introducing the MDF process.The ultimate tensile strength(UTS),yield strength(YS)and elongation are279 MPa,185 MPa and 12%at the bottom and 299 MPa,212 MPa and 20%at the wall.
基金Project supported by the National Natural Science Foundation of China (5150101551871195)。
文摘The microstructures and strengthening mechanisms of the Mg-8.2 Gd-4.6 Y-1.5 Zn-0.4 Zr(wt%) alloy with long-period stacking ordered(LPSO),β’ and γ type phases were systematically studied.The results show that the LPSO with lamellar and block structures forms near the grain boundaries.The grains are clearly refined,and the 18 R LPSO phase is oriented along the extrusion direction after extrusion.Some particles also precipitate from the Mg matrix dynamically.The extruded alloy exhibits a remarkable agehardening response,and mechanical properties,with a tensile strength(TS) of 449 MPa,yield strength(YS) of 362 MPa,and elongation of 7.9% obtained in the peak-aged alloy.The strengthening mechanisms of the alloy in different states are discussed.Grain boundary and precipitation strengthening are the main strengthening mechanisms for the peak-aged alloy.
基金supported by the National Natural Science Foundation of China(31101538,31000942 and 31000676)the Grand Science and Technology Special Project of Zhejiang Province,China(2010C02006)the Public Welfare Project of Zhejiang Province,China(2011R23A52D04)
文摘Polyamines play important roles in plant tolerance to environmental stress. With the aim of investigating the possible involvement of putrescine （Put） in salt-tolerance mechanisms in vegetable soybean roots, exogenous Put （10 mmol L＂） and its biosynthetic inhibitor D-arginine （D-Arg） （0.5 mmol L-1） were added to nutrient solution when vegetable soybean （Glycine max L. cv. Huning 95-1） seedlings were exposed to 100 mmol L^-11 sodium chloride （NaCl）. The results showed that Put ameliorated but D-Arg aggravated the detrimental effects of NaCl on plant growth and biomass production. Under NaCl stress, levels of free, soluble conjugated and insoluble bound types of Put in roots of vegetable soybean were reduced, whereas those of free, soluble conjugated, and insoluble bound types of spermidine （Spd） and spermine （Spm） were increased. Exogenous Put eliminated the decrease in Put but promoted the increase of Spd and Spm. However, these changes could be reversed by D-Arg. Under NaCl stress, activities of arginine decarboxylase （ADC）, S-adenosylmethionine decarboxylase （SAMDC）, diamine oxidase （DAO）, and polyamine oxidase （PAO） were induced, with exogenous Put promoting and D-Arg reversing these changes. Furthermore, NaCl stress decreased activities of antioxidant enzymes. Exogenous Put alleviated but D-Arg exaggerated these effects of NaCl stress, resulting in the same changes in membrane damage and reactive oxygen species （ROS） production. These results indicated that Put plays a positive role in vegetable soybean roots by activating antioxidant enzymes and thereby attenuating oxidative damage.
基金supported by the National Basic Research Program of China(2013CB632202)the Natural Science Foundation of China(51501015,51871195,51874062).
文摘The effects of minor Zn(0.2 at%,0.4 at%,0.6 at%) on the microstructures and mechanical properties of Mg-1.4 Gd-1.2 Y-0.15 Zr(at%) alloys were systematically explored.Results reveal that increasing Zn content leads to the increase of the intergranular phases and the change of their composition from Mg24(Gd,Y)5 phase and(Mg,Zn)3(Gd,Y) phase to 18 R-LPSO phase and(Mg,Zn)3(Gd,Y) phase.Mg24(Gd,Y)5 phase is body-centered cubic structure and shares the same lattice constant with Mg24Y5 while(Mg,Zn)3(Gd,Y)phase is face-centered cubic structure with lattice constant of 0.72 nm,slightly lower than Mg3Gd.18RLPSO structure is identified to be monoclinic with c-axis not strictly vertical to the bottom surface but93.5°.The growth patterns of intergranular phases change from the divorced growth to coupled growth as compositions change.Moreover,the mechanical performance improves with Zn rising,ascribed to the decrease of brittle phases at grain boundaries and the increase of LPSO structure phases.
基金financially supported by the National Natural Science Foundation of China (Nos. 51004016 and 51004017)the National High Technology Research and Development Program of China (Nos.2012AA110102 and 2011AA11A269)
文摘Silicon has been investigated extensively as a promising anode material for rechargeable lithium-ion bat- teries. Understanding the failure mechanism of silicon-based anode electrodes for lithium-ion batteries is essential to solve the problem of low coulombic efficiency and capacity fading on cycling and also to further commercialize this very new energetic material in cells. To reach this goal, the structure changes of bulk silicon particles and electrode after cycling were studied using ex-situ scanning electron microscopy （SEM） and X-ray diffraction （XRD） techniques. The SEM images indicated that the microstructural changes of the bulk silicon particles during cycling led to a layer rupture of the electrode and then the breakdown of the conductive network and the failure of the electrode. The result contributes to the basic understanding of the failure mechanism of a bulk sil- icon anode electrode for lithium-ion batteries.
基金supported by the Talent Foundation of Anhui Science and Technology University (No. ZRC2014401)
文摘A highly effective phase transfer of a quaternary ammonium gemini surfactant with ester groups（（diethylhexanedioate） diyl-a,v-bis（dimethyl dodecyl ammonium bromide） referred to as 12-10-12）was synthesized with high yield and characterized by infrared spectroscopy, elemental analysis and1 HNMR. Then, 12-10-12 was used as a phase transfer catalyst to study the catalytic effect on the reaction of anhydrous sodium acetate and 4-methylbenzyl chloride. The possible catalytic mechanism and the influence of surfactant concentration, temperature and type are also discussed. The experimental results showed that the catalysis efficiency was more active than the traditional, single-chained surfactant,tetrabutyl ammonium bromide. It also revealed that the reaction was first-order with respect to the concentration of 4-methylbenzyl chloride. The concentration of 4-methylbenzyl chloride grew linearly with the concentration of 12-10-12 and as the reaction temperature increased. The optimum reaction time was 7 h.
基金Supported by the National Natural Science Foundation of China(No.81173461)China Scholarship Council(No.201306100055)
文摘OBJECTIVE： To investigate, in terms of Notch signaling pathway, the effect on pancreatic cancer of the extract of an anti-tumor prescription -- Qingyihuaji formula （QYHJ） -- from Traditional Chinese Medicine （TCM）.METHODS： Nude mice were implanted subcutaneously with human pancreatic cancer cell line SW1990 and then randomly divided into four groups： Control, QYHJ extract, Gemcitabine, and Combination of QYHJ extract and gemcitabine. Treatments were given for 21 days and tumor growth was evaluated simultaneously. Then, expression of Notch receptors （Notch-I, Notch-2, Notch-3, and Notch-4） and their Jagged ligands （Jagged-1 and Jagged-2） in dissected tumor tissue were detected by real-time quantitative reverse transcription-polymerase chain reaction and Western blot. Finally, immunohistochemistry was performed to detect CD133, a marker of pancreatic cancer stem cells （CSCs）, to evaluate the impact of QYHJ extract on pancreatic CSCs.RESULTS： QYHJ extract treatment effectively inhib- ited the tumor growth in nude mice. The expression of both Notch-4 and Jagged-1 were decreased significantly in QYHJ treatment groups （P 〈 0.05）, while gemcitabine alone had no significant effect in down-regulating Jagged-1 （P 〉 0.05）. No significant difference was observed in the ex- pression of Notch-1, Notch-2, Notch-3, and Jagged-2 between three treatment groups and control group （P 〉 0.05）. Moreover, immunohistochemical analysis showed that the number of CD133 positive cells was significantly reduced by QYHJ treatment （P 〈 0.05）, and the combined treatment was more effective than gemcitabine alone （P 〈 0.05）.CONCLUSION： The role of the extract in pancreatic cancer treatment was associated with down-regulation of Notch-4 and Jagged-1 in Notch signaling pathway. The extract could enhance the antitumor activity of gemcitabine and was more effective than gemcitabine in regulating Notch signaling pathway to some extent.
文摘Based on the industrial production of non-oriented silicon steel,calcium treatment by CaSi wire feeding during the RH refining process was studied. The thermodynamics of CaS inclusion formation was analyzed, and the morphology and the size distribution were observed. Furthermore, the change in inclusion characteristics after calcium treatment and the effect of calcium treatment on magnetic properties were discussed. The results show that the formation of MnS and A1N inclusions were restrained, and the aggregating, floating and removing of microinclusions after calcium treatment were effectively promoted. The cleanliness of liquid steel was obviously increased. The main type of inclusions was single phase of CaO, with some complex inclusions composed of CaO, SiO2 and MgO. No CaS inclusion was observed after an appropriate calcium treatment. The size of all inclusions was distributed in the range of 2 - 20 μm, and the number was about 1.8 × 10^5/mm3. In addition, as an increasing amount of calcium was added,the core loss gradually decreased to a stable level, and the magnetic induction decreased quickly after a slow increase. The optimal calcium treatment mode depends on the chemical composition of steel.
基金financially supported by the Postdoctoral Science Research Developmental Foundation of Heilongjiang Province (No. LBH-Q12004)the Education Department Foundation from Heilongjiang Province (No.11521575)the Science and Technology Project of Mudanjiang, Heilongjiang Province, China (No.G2012g0008)
文摘Compound ceramic coatings with the main crystalline of Al_2TiO_5（in the as-prepared coating without treatment） were prepared in situ on the surface Ti-6Al-4V alloy by means of pulsed bipolar micro-arc oxidation in Na AlO_2 solution. For the purpose of studying the antioxidation properties of the samples, the coated samples treated in argon and the as-coated samples were calcined in air at 1000 °C. And the related characteristics were investigated by X-ray diffraction（XRD）, scanning electron microscopy（SEM） and X-ray fluorescence（XRF） spectroscopy, respectively. The results show that, when it was calcined in air for 1 h, Al_2TiO_5in the as-prepared coating decomposed and transformed into α-Al_2O_3 and rutile TiO_2.However, after almost 4 h in argon, Al_2TiO_5in the asprepared coating decomposed and the final coating surface contents are completely α-Al_2O_3, and those of the middle interface are mainly Al_2O_3 and Ti_2O_3. The morphologies of the coatings after calcination in argon and air are different.High-temperature oxidation occurred violently in the alloy substrate without coatings. Furthermore, the weight gain curves of the as-prepared samples and the coated samples treated in argon both show a parabolic shape.
基金the National Natural Science Foundation of China(Grant no.51501015).
文摘High temperature deformation behavior and workability of Mg-8.1 Gd-4.5Y-0.3Zr alloy were studied by compression tests.Arrhenius equation with strain compensation and processing maps were established.The results show that the activation energy Q,structure factor a,n and In A varies with the strain,its relationship fit well by fifth order polynomial.The flow stresses predicted by the extracted model are in good agreement with the experimental results.There are five typical domains in the processing map,and the deformation mechanisms in different domains were determined by microstructure analysis.The feasible processing window of the alloy is in the areas of 400-500℃/0.001-0.1 s^(-1).
