Nd-Fe-B permanent magnets play a crucial role in energy conversion and electronic devices.The essential magnetic properties of Nd-Fe-B magnets,particularly coercivity and remanent magnetization,are significantly infue...Nd-Fe-B permanent magnets play a crucial role in energy conversion and electronic devices.The essential magnetic properties of Nd-Fe-B magnets,particularly coercivity and remanent magnetization,are significantly infuenced by the phase characteristics and microstructure.In this work,Nd-Fe-B magnets were manufactured using vacuum induction melting(VIM),laser directed energy deposition(LDED)and laser powder bed fusion(LPBF)technologies.Themicrostructure evolution and phase selection of Nd-Fe-B magnets were then clarified in detail.The results indicated that the solidification velocity(V)and cooling rate(R)are key factors in the phase selection.In terms of the VIM-casting Nd-Fe-B magnet,a large volume fraction of theα-Fe soft magnetic phase(39.7 vol.%)and Nd2Fe17Bxmetastable phase(34.7 vol.%)areformed due to the low R(2.3×10-1?C s-1),whereas only a minor fraction of the Nd2Fe14B hard magnetic phase(5.15 vol.%)is presented.For the LDED-processed Nd-Fe-B deposit,although the Nd2Fe14B hard magnetic phase also had a low value(3.4 vol.%)as the values of V(<10-2m s-1)and R(5.06×103?C s-1)increased,part of theα-Fe soft magnetic phase(31.7vol.%)is suppressed,and a higher volume of Nd2Fe17Bxmetastable phases(47.5 vol.%)areformed.As a result,both the VIM-casting and LDED-processed Nd-Fe-B deposits exhibited poor magnetic properties.In contrast,employing the high values of V(>10-2m s-1)and R(1.45×106?C s-1)in the LPBF process resulted in the substantial formation of the Nd2Fe14B hard magnetic phase(55.8 vol.%)directly from the liquid,while theα-Fe soft magnetic phase and Nd2Fe17Bxmetastable phase precipitation are suppressed in the LPBF-processed Nd-Fe-B magnet.Additionally,crystallographic texture analysis reveals that the LPBF-processedNd-Fe-B magnets exhibit isotropic magnetic characteristics.Consequently,the LPBF-processed Nd-Fe-B deposit,exhibiting a coercivity of 656 k A m-1,remanence of 0.79 T and maximum energy product of 71.5 k J m-3,achieved an acceptable magnetic performance,comparable to other additive manufacturing processed Nd-Fe-B magnets from MQP(Nd-lean)Nd-Fe-Bpowder.展开更多
Ternary strategy with a suitable third component is a successful strategy to improve the photovoltaic performance of organic solar cells(OSCs).Very recently,Y-series based giant molecule acceptors or oligomerized acce...Ternary strategy with a suitable third component is a successful strategy to improve the photovoltaic performance of organic solar cells(OSCs).Very recently,Y-series based giant molecule acceptors or oligomerized acceptors have emerged as promising materials for achieving highly efficient and stable binary OSCs,while application as third component for ternary OSCs is limited.Here a novelπ-extended giant dimeric acceptor,GDF,is developed based on central Y series core fusion and rigid BDT as linker,and then incorporated into the state-of-the-art PM1:PC6 system to construct ternary OSCs.The GDF has a near planar backbone,resulting in increasedπ-conjugation,excellent crystallinity,and good electron transport capacity.When GDF is introduced into the PM1:PC6 system,it ensues in a cascade like the lowest unoccupied molecular orbitals(LUMO)energy level alignment,a complementary absorption band with PM1 and PC6,higher and balanced hole and electron mobility,slightly smaller domain size,and a higher exciton dissociation probability for PM1:PC6:GDF(1:1.1:0.1)blend film.As a consequence,the PM1:PC6:GDF(1:1.1:0.1)ternary OSC achieves a champion PCE of 19.22%,with a significantly higher open-circuit voltage and short-circuit current density,compared to 18.45%for the PM1:PC6(1:1.2)binary OSC.Our findings show that employing aπ-extended giant dimeric acceptor as a third component significantly improves the photovoltaic performance of ternary OSCs.展开更多
In the present study,the effects of process parameters(output voltage x,nitrogen flux l and specific strengthening time s)on the microstructure and wear resistance properties of TiN coatings prepared by electrospark d...In the present study,the effects of process parameters(output voltage x,nitrogen flux l and specific strengthening time s)on the microstructure and wear resistance properties of TiN coatings prepared by electrospark deposition(ESD)were investigatedsystematically.The microstructure of the coatings was characterized for thickness(TOC),content of TiN(CON)and porosity(POC).A statistical model was developed to identify the significant factors affecting the microstructure and wear resistance of the coatings.The results show that the output voltage x and nitrogen flux l present significant effects on majority of the evaluation indexes such asTOC,friction coefficient(COF)and wear mass loss(Id),while the specific strengthening time s has a significant effect on POC and asmall effect on the other indexes.The optimal process parameters were obtained as follows:output voltage(x,60V),nitrogen flux(l,15L/min)and specific strengthening time(s,3min/cm2).The variation of wear mass loss(Id)by the variation of the outputvoltage(x)and nitrogen flux(l)is attributed to the change of wear mechanisms of TiN coatings.The main wear mechanism of TiNcoating prepared under optimal process parameters is micro-cutting wear accompanied by micro-fracture wear.展开更多
Laser additive manufacturing technology with powder feeding was employed to repair wrought Ti17titanium alloy with small surface defects.The microstructure,micro-hardness and room temperature tensile properties of las...Laser additive manufacturing technology with powder feeding was employed to repair wrought Ti17titanium alloy with small surface defects.The microstructure,micro-hardness and room temperature tensile properties of laser additive repaired(LARed)specimen were investigated.The results show that,cellular substructures are observed in the laser deposited zone(LDZ),rather than the typicalαlaths morphology due to lack of enough subsequent thermal cycles.The cellular substructures lead to lower micro-hardness in the LDZ compared with the wrought substrate zone which consists of duplex microstructure.The tensile test results indicate that the tensile deformation process of the LARed specimen exhibits a characteristic of dramatic plastic strain heterogeneity and fracture in the laser repaired zone with a mixed dimple and cleavage mode.The tensile strength of the LARed specimen is slightly higher than that of the wrought specimen and the elongation of11.7%is lower.展开更多
The microstructure, microhardness and tensile properties of laser additive manufactured (LAM) Ti?5Al?2Sn?2Zr?4Mo?4Cr alloy were investigated. The result shows that the microstructure evolution is strongly affected by ...The microstructure, microhardness and tensile properties of laser additive manufactured (LAM) Ti?5Al?2Sn?2Zr?4Mo?4Cr alloy were investigated. The result shows that the microstructure evolution is strongly affected by the thermal history of LAM process. Primary α (αp) with different morphologies, secondary α (αs) and martensite α' can be observed at different positions of the LAMed specimen. Annealing treatment can promote the precipitation of rib-like α phase or acicular α phase. As a result, it can increase or decrease the microhardness. The as-deposited L-direction and T-direction specimens contain the same phase constituent with different morphologies. The tensile properties of the as-deposited LAMed specimens are characterized of anisotropy. The L-direction specimen shows the character of low strength but high ductility when compared with the T-direction specimen. After annealing treatment, the strength of L-direction specimen increases significantly while the ductility reduces. The strength of the annealed T-direction specimen changes little, however, the ductility reduces nearly by 50%.展开更多
To search for new cathode materials with high energy density of Lithium-ion batteries(LIBs) is one of the most challenging issues. Vanadium pentoxide(V2 O5) with high theoretical specific capacity is believed to be a ...To search for new cathode materials with high energy density of Lithium-ion batteries(LIBs) is one of the most challenging issues. Vanadium pentoxide(V2 O5) with high theoretical specific capacity is believed to be a promising candidate for the next generation cathode materials, yet still suffers from low lithium ion diffusion coefficient and poor electronic conductivity resulting in low cycling life and poor rate performances. Here, we report new large-scale carambola-like V2 O5 nanoflowers arrays anchored on microporous reed carbon as high performances LIBs cathode. Each individual pore space of the microporous reed carbon is like a hexagonal cylinder, and the area of each carbon wall is more than103 um2, which is favorable for the growth of V2 O5 nanostructure arrays. After hydrothermal, the largescale carambola-like V2 O5 nanoflowers arrays can directly grow on the surface of microporous carbon.Due to the novel composite structures, the V2 O5 nanoflowers arrays@microporous carbon stabilizes at273 mA h g^(-1) after 100 cycles at 0.2 C. When cycling at 1.0 C over 500 cycles, the capacity still maintains at 180 mAh g^(-1). The demonstrated approach in this work paves the way for the development of high rate capability and excellent cycling stability V2 O5-based cathode materials.展开更多
Two novel asymmetric organic small molecules of IT(2FBT-T3Cz)_2and IT(2FBT-TT3Cz)_2with an indenothiophene(IT)central donor core,fluorinated benzothiadiazole(2FBT)as acceptor and 3-carbazole(Cz)unit as terminal group ...Two novel asymmetric organic small molecules of IT(2FBT-T3Cz)_2and IT(2FBT-TT3Cz)_2with an indenothiophene(IT)central donor core,fluorinated benzothiadiazole(2FBT)as acceptor and 3-carbazole(Cz)unit as terminal group were designed and synthesized as the donor materials in organic solar cells(OSCs).The thermal,optical absorption,electrochemical property,hole–electron mobility,film morphology were thoroughly studied.Using PC_(71)BM as an electron acceptor,without any additive and thermal annealing(TA)treatment,the IT(2FBT-T3Cz)_2-based cells showed a promising power conversion efficiency(PCE)of5.81%and the IT(2FBT-TT3Cz)_2-based cells exhibited a PCE of 4.39%.Our results demonstrate that the IT-based asymmetric small molecules can be developed as a promising class of donor materials for highperformance OSCs.展开更多
Total 20 maize varieties were subjected to drought stress at flowering stage,and then the relative water content,soluble sugar content,chlorophyll content,malondialdehyde( MDA) content and superoxide dismutase( SOD) a...Total 20 maize varieties were subjected to drought stress at flowering stage,and then the relative water content,soluble sugar content,chlorophyll content,malondialdehyde( MDA) content and superoxide dismutase( SOD) activity in their leaves,as well as their yields were determined. The drought tolerance of the physiological and biochemical indexes was scored by five-level scoring method,and the drought tolerance index was calculated by the yield index to comprehensively evaluate the drought tolerance of maize during flowering stage. The results showed that the scores of drought tolerance of the maize varieties ranged from 1. 929 3 to 5. 659 5. Among them,the scores of Zhengda 619,Guidan 162 and Guidan 0810 were greater than 5. 0,followed by Dika 008,Xianyu 30 T60,Xianzhengda 901,Qingnong 68,South America No. 1 and Wanchuan 1306 of which the scores were in the range of 4. 0-5. 0. The drought tolerance indexes were in the range of 0. 410 4-1. 096 3. Among the test maize varieties,the drought tolerance indexes of Guidan 0810,Pacific 99 and Zhengda 619 were greater than 1. 0,and those of Xianyu 30 T60,Dika 008 and South America No. 1 were in the range of 0. 9-1. 0. The correlation between the two kinds of evaluation results was 0. 588 7 and was extremely significant. The five-level scoring method and the drought tolerance index can be used simultaneously for the evaluation of drought tolerance of maize during flowering stage. The two aspects of evaluation results showed that Guidan 0810,Zhengda 619,Xianyu 30 T60,Dika 008 and South America No. 1 were drought-tolerant varieties,among which Guidan 0810 and Zhengda 619 were extremely highly drought-tolerant varieties.展开更多
Based on isobaric tags for relative and absolute quantification(iTRAQ)technology,the proteome of grains of a maize cultivar Huangzao 4 under drought stress at grain filling stage was analyzed.The results show that und...Based on isobaric tags for relative and absolute quantification(iTRAQ)technology,the proteome of grains of a maize cultivar Huangzao 4 under drought stress at grain filling stage was analyzed.The results show that under drought stress,438 proteins were differentially expressed in the maize grains during grain filling.Among them,200 were up-regulated and 238 were down-regulated.The gene ontology(GO)analysis shows that the biological processes in which differential proteins are more involved are cellular processes,metabolic processes and single biological processes;proteins in the cell component category are mainly distributed in cells,cell parts and organelles;and the proteins the molecular function category mainly possess catalytic activity and binding function.Differentially expressed proteins classified by COG are mainly involved in protein post-translational modification and transport,molecular chaperones,general functional genes,translation,ribosomal structure,biosynthesis,energy production and transformation,carbohydrate transport and metabolism,amino acid transport and metabolism,etc.The subcellular structure of the differentially expressed proteins is mainly located in the cell chloroplast and cytosol.The proportions are 35.01%and 30.21%respectively.KEGG metabolic pathway enrichment analysis shows that the differentially expressed proteins are mostly involved in antibiotic biosynthesis,microbial metabolism in different environments,and endoplasmic reticulum protein processing;the metabolic pathways with higher enrichment are the carbon fixation pathway and estrogen signaling pathway of prokaryotes;and the higher enrichment and greater significance are in the tricarboxylic acid cycle,carbon fixation of photosynthetic organisms and proteasome.The results of this study preliminarily reveal the adaptive mechanism of maize grains in response to drought stress during grain filling,providing a theoretical reference for maize drought-resistant molecular breeding.展开更多
[Objectives]This study aimed to explore the effect of different concentrations of selenium fertilizer on the yield,selenium content and heavy metal contents of waxy maize,thereby providing reference for the scientific...[Objectives]This study aimed to explore the effect of different concentrations of selenium fertilizer on the yield,selenium content and heavy metal contents of waxy maize,thereby providing reference for the scientific application of selenium fertilizer on waxy maize.[Methods]Different varieties of waxy maize(Guitiannuo 611,Guinuo 615 and Guiheinuo 609)were used as test materials.They were sprayed with different concentrations(0,0.5,1.0,1.5 and 2.0 g/L)of water-soluble selenium fertilizer(Xinxibao)at the big flare stage,and the effect on the yield,selenium content and heavy metal contents of the waxy maize was analyzed.[Results]Foliar application of different concentrations of selenium fertilizer showed no significant effect on the yield and yield components of waxy maize.As the concentration of selenium fertilizer increased,the grain selenium content of different varieties of waxy maize increased.Among them,the increase of Guinuo 615 was the largest,of which the selenium content reached 0.265 mg/kg,2.82 times that of the control(water).The cadmium and arsenic contents of different varieties of waxy maize decreased with the increase of the concentration of selenium fertilizer sprayed.Among the waxy maize varieties,the cadmium and arsenic contents of Guitiannuo 611 dropped the most significantly,up to 52.94%and 77.78%.In waxy maize,the correlation coefficients between selenium content and cadmium,arsenic contents were-0.5509(P<0.05)and-0.8530(P<0.01),respectively.[Conclusions]Spraying exogenous selenium fertilizer had no obvious effect on the yield of waxy maize.However,the increase of the concentration of exogenous selenium fertilizer could significantly increase the selenium content and reduce the cadmium and arsenic contents in grains of different varieties of waxy maize.展开更多
Laser cladding deposited Ti-6Al-4V titanium alloy universally shows more complex microstructures,each of which has significant effect on mechanical properties. Of particular α/β interface phase has been observed in ...Laser cladding deposited Ti-6Al-4V titanium alloy universally shows more complex microstructures,each of which has significant effect on mechanical properties. Of particular α/β interface phase has been observed in this paper under certain conditions. It demonstrates that the influence of the α/β interface phase on the tensile properties is closely associated with dislocations and twin substructure through comparison experiments. The results show that the α/β interface phase hinders dislocation motion and decreases effective slip length. In addition, the twin substructure has been activated in the α/β interface phase during tensile process and has acted somehow like grain boundaries. Therefore, the strength and the work-hardening rate of the laser cladding deposited Ti-6Al-4V titanium alloy have been significantly improved due to the dynamic Hall-Petch effect. Besides, the α/β interface phase leads to more uniform dislocations distribution, which implies that relative lower local concentrated stress will be produced along the α/β interface phase or colony boundary after the same amount of plastic deformation. Moreover,the twinning-induced plasticity effects in the α/β interface phase further increase the plastic deformation capacity. These results in higher elongation for the laser cladding deposited Ti-6Al-4V titanium alloy.It can be concluded that the current work suggests an effective method to simultaneously improve the strength and plasticity of laser cladding deposited Ti-6Al-4V titanium alloy based on the α/β interface phase.展开更多
Improving the low-cycle fatigue(LCF)properties of additively manufactured Ti-5.6Al-3.8V alloy is critical in ensuring its service safety and represents a significant research challenge.This work discusses a so-lution ...Improving the low-cycle fatigue(LCF)properties of additively manufactured Ti-5.6Al-3.8V alloy is critical in ensuring its service safety and represents a significant research challenge.This work discusses a so-lution that optimizes the alloy's microstructure and ductility by precisely controlling the over-saturated strengthening elements and heat treatment.This was accomplished using selective laser melting(SLM),heat treatment at 800 ℃ for 2 h,and furnace cooling on a Ti-5.6Al-3.8V alloy with tightly controlled Al,V,and O concentrations in a lower range.The results showed that the SLM-fabricated Ti-5.6Al-3.8V alloy,post-heat treatment,exhibited α laths with a width of~1.4 μm and β columnar grains with a diameter of~126 μm,without experiencing coarsening or variant selection phenomena.The alloy bal-anced strength and ductility post-heat treatment with a UTS of 1015 MPa and an EL of 16.5%relative to the as-deposited state(UTS of 1199 MPa and EL of 11.9%).Notably,the LCF properties of the heat-treated SLM Ti-5.6Al-3.8V alloy are superior to those of other Ti-6Al-4V alloys produced by additive manu-facturing and comparable to traditional forgings.At high strain amplitudes(1-1.5%),the fatigue life of this alloy was twice that of the Ti-6Al-4V forgings.Furthermore,we comprehensively analyzed the mi-crostructure,strength,and ductility of the SLM Ti-5.6Al-3.8V alloy to elucidate the factors influencing its LCF properties.These findings provide a solid foundation for improving the LCF properties of additively manufactured Ti-6Al-4V alloy,thereby contributing to its safe and reliable use in critical applications.展开更多
Meeting the damage tolerance requirements for engineering-grade titanium alloys pose a significant challenge in achieving high fracture toughness in direct energy deposition(DED)titanium alloys.This work primarily inv...Meeting the damage tolerance requirements for engineering-grade titanium alloys pose a significant challenge in achieving high fracture toughness in direct energy deposition(DED)titanium alloys.This work primarily investigated the relationship between the microstructure and the fracture toughness of DED new Ti-6Al-4V-1Mo alloy.Two types of microstructures were designed via two process strategies:high-line energy density(HE)and low-line energy density(LE).Relative to LE samples,HE samples possess larger-sized microstructural characteristics(coarser grain boundaryα(α_(GB)),largerαcolonies,and coarserαlaths).Lessα/βphase boundaries were formed by coarserαlaths in the HE samples,increasing the movement of dislocations,resulting in tensile strength decreasing from 1007.1 MPa(LE)to 930.8 MPa(HE)and elongation increasing from 10.8%(LE)to 15.7%(HE).Also,HE samples exhibited an excellent fracture toughness of 114.0 MPa m^(1/2),significantly higher than that of LE samples(76.8 MPa m^(1/2)).An analysis of crack propagation paths was conducted to investigate the factors contributing to toughening.The primary factor enhancing toughness is the frequent obstruction of cracks by coarseαGB and largeαcolonies in HE samples.Particularly,the pretty large-angle deflections induced by the superposition effect of coarseαGB and largeαcolonies play a vital of significant role.These factors induced the long and tortuous high-energy pathways,which resulted in ultimately improved fracture toughness.The discovered microstructural toughening mechanisms can serve as a reference for future studies involving titanium alloys,offering insights on how to enhance fracture toughness by achieving similar characteristics.展开更多
Solidification microstructure of powder fed laser additive manufactured Ti-6Al--2Zr--2Sn--3Mo--1.5Cr--2Nb titanium alloy was investigated, The results showed that by deliberately increasing the powder feed rate, parti...Solidification microstructure of powder fed laser additive manufactured Ti-6Al--2Zr--2Sn--3Mo--1.5Cr--2Nb titanium alloy was investigated, The results showed that by deliberately increasing the powder feed rate, partially melted powders were retained at the top of the molten pool, which can promote heteroge- neous nucleus. Thus, each cladding layer is composed of two regions： （i） randomly orientated cellular structure region caused by partially melted powders at the top of each cladding layer; and （ii） epitaxial cellular structure region adjacent to the fusion line. Usually, randomly orientated cellular structure region was totally remelted for a wide range of process conditions. The remelting effect ensures the continuity of epitaxial growth of cellular structure and leads to the formation of columnar β grains, In order to obtain equiaxed grains the scanning velocity and powder feed rate should be carefully selected to enlarge the randomly orientated cellular structure region,展开更多
The heterogeneous integration of photonic integrated circuits(PICs)with a diverse range of optoelectronic materials has emerged as a transformative approach,propelling photonic chips toward larger scales,superior perf...The heterogeneous integration of photonic integrated circuits(PICs)with a diverse range of optoelectronic materials has emerged as a transformative approach,propelling photonic chips toward larger scales,superior performance,and advanced integration levels.Notably,two-dimensional(2D)materials,such as graphene,transition metal dichalcogenides(TMDCs),black phosphorus(BP),and hexagonal boron nitride(hBN),exhibit remarkable device performance and integration capabilities,offering promising potential for large-scale implementation in PICs.In this paper,we first present a comprehensive review of recent progress,systematically categorizing the integration of photonic circuits with 2D materials based on their types while also emphasizing their unique advantages.Then,we discuss the integration approaches of 2D materials with PICs.We also summarize the technical challenges in the heterogeneous integration of 2D materials in photonics and envision their immense potential for future applications in PICs.展开更多
Background:Cell salvage has recently been recommended for obstetric use in cases with a high risk of massive hemorrhage during cesarean section(CS).However,limited data are available to support the use of one suction ...Background:Cell salvage has recently been recommended for obstetric use in cases with a high risk of massive hemorrhage during cesarean section(CS).However,limited data are available to support the use of one suction device to collect lost blood.This study aimed to investigate the volume of red blood cells(RBCs)salvaged and the components of amniotic fluid(AF)in blood salvaged by one suction device or two devices during CS in patients with placenta previa and/or accrete.Methods:Thirty patients with placenta previa and/or accrete undergoing elective CS in the Women's Hospital of Zhejiang University School of Medicine were recruited for the present study from November 1,2017 to December 1,2018.The patients were randomly assigned to one of the two groups according to an Excel-generated random number sheet:Group 1(w=15),in which only one suction device was used to aspirate all blood and AF,and Group 2(w=15),in which a second suction device was mainly used to aspirate AF before the delivery of the placenta.Three samples of blood per patient(pre-wash,post-wash,and post-filtration)were collected to measure AF components.The salvaged RBC volumes were recorded.Continuous data of pre-wash,post-wash,and postfiltration samples were analyzed by using one-way analysis of variance with Tukey5s test for multiple comparisons,or Kruskal-Wallis test with Dunn test for multiple comparisons.Comparisons of continuous data between Group 1 and Group 2 were conducted using Student's t test or Mann-Whitney U test.Results:The salvaged RBC volume was significantly higher in Group 1 than that in Group 2(401.6±77.2 mL vs.330.1土53.3 mL,?=4.175,P<0.001).In both groups,squamous cells,lamellar bodies,and fat were significantly reduced by washing(all P<0.001)and squamous cells were further reduced by filtering(P<0.001).Squamous cells were found in six post-filtration samples(three from each group).Lamellar bodies and fat were completely removed by filtering.Insulin-like growth factor binding protein 1,alphafetoprotein,albumin,lactate dehydrogenase,and potassium were significantly reduced post-wash(all P<0.05),with no further significant reduction after filtration in either group(all P>0.05).The mean percentage of fetal RBCs post-filtration was(1.8±0.8)%with a range of 1.0%to 3.5%and(1.9±0.9)%with a range of 0.7%to 4.0%in Groups 1 and 2,respectively,showing no significant difference between the two groups(U=188.5,P=0.651).Conclusion:Cell salvage performed by one suction device could result in higher volume of salvaged RBCs and can be used safely for CS in patients with placenta previa and/or accrete when massive hemorrhage occurs.Trial registration number:ChiCTR-INR-17012926,http://www.chictr.org.cn/Chinese Clinical Trial Registry.展开更多
Aqueous Zinc-ion batteries(ZIBs),using zinc negative electrode and aqueous electrolyte,have attracted great attention in energy storage field due to the reliable safety and low-cost.A composite material comprised of V...Aqueous Zinc-ion batteries(ZIBs),using zinc negative electrode and aqueous electrolyte,have attracted great attention in energy storage field due to the reliable safety and low-cost.A composite material comprised of VO2·0.2H2O nanocuboids anchored on graphene sheets(VOG)is synthesized through a facile and efficient microwave-assisted solvothermal strategy and is used as aqueous ZIBs cathode material.Owing to the synergistic effects between the high conductivity of graphene sheets and the desirable structural features of VO2·0.2H2O nanocuboids,the VOG electrode has excellent electronic and ionic transport ability,resulting in superior Zn ions storage performance.The Zn/VOG system delivers ultrahigh specific capacity of 423 mAh·g^−1 at 0.25 A·g^−1 and exhibits good cycling stability of up to 1,000 cycles at 8 A·g^−1 with 87%capacity retention.Systematical structural and elemental characterizations confirm that the interlayer space of VO2·0.2H2O nanocuboids can adapt to the reversible Zn ions insertion/extraction.The as-prepared VOG composite is a promising cathode material with remarkable electrochemical performance for low-cost and safe aqueous rechargeable ZIBs.展开更多
Thin-wall structures of Ti-6A1-4V were fabricated by low-power pulsed laser directed energy deposition. During deposition, consistent with prior reports, columnar grains were observed which grew from the bottom toward...Thin-wall structures of Ti-6A1-4V were fabricated by low-power pulsed laser directed energy deposition. During deposition, consistent with prior reports, columnar grains were observed which grew from the bottom toward the top of melt pool tail. This resulted in a microstructure mainly composed of long and thin prior epitaxial β columnar grains (average width ^200μm). A periodic pattern in epitaxial growth of grains was observed, which was shown to depend upon laser traverse direction. Utilizing this, a novel means was proposed to determine accurately the fusion boundary of each deposited layer by inspection of the periodic wave patterns. As a result it was applied to investigate the influence of thermal cycling on microstructure evolution. Results showed that acicular martensite,α' phase, and a small amount of Widmanstatten, a laths, gradually converted to elongated acicular a and a large fraction of Widmanstatten a laths under layer-wise thermal cycling. Tensile tests showed that the yield strength, ultimate tensile strength and elongation of Ti-6Al-4V thin wall in the build direction were 9.1 %, 17.3% and 42% higher respectively than those typically observed in forged solids of the same alloy. It also showed the yield strength and ultimate tensile strength of the transverse tensile samples both were 13.3% higher than those from the build direction due to the strengthening effect of a large number of vertical β grain boundaries, but the elongation was 69.7% lower than that of the build direction due to the uneven grain deformation of β grains.展开更多
Although a variety of processing routes were developed to in-situ manipulate microstructure for fabricating high-performance Ti-6Al-4 V alloy by directed energy deposition(DED),the in-situ microstructural control abil...Although a variety of processing routes were developed to in-situ manipulate microstructure for fabricating high-performance Ti-6Al-4 V alloy by directed energy deposition(DED),the in-situ microstructural control ability has been limited and lead to a narrowed mechanical property control range.This work proved the microstructural correlation betweenβ-grains andα-laths resulting from the unique thermal characteristics of DED for the first time and solved such a dilemma through synchronous induction heating assisted laser deposition(SILD)technology.The results confirmed that the laser energy and inductive energy have a different effect on the solidification and solid phase transformation conditions.By adjusting the laser-induction parameters,the microstructural correlation can be tuned;theβ-grains andα-laths can be controlled relatively separately,thereby significantly enhancing the ductility of as-deposited sample(elongation from 14.2%to 20.1%).Furthermore,the mechanical properties of the tuned microstructures are even comparable to that of DED Ti-6Al-4 V with post heat treatment,which indicates that the potential of SILD to be a one-step manufacturing process to fabricate high performance components without post heat treatment.Furthermore,the tensile testing results of the tuned microstructures indicate thatα-lath size is more influential on the mechanical properties than theβ-grain size due to its stronger hindering effect on the slipping of dislocations.This work promotes the understanding of the microstructural formation mechanism in DED titanium alloy and proves that the combination of synchronous induction and laser can expand the ability to control the microstructure and properties of multi-layer deposition.展开更多
In this review,the evolution of high strain Na_(0.5)Bi_(0.5)TiO_(3)-based lead-free piezoceramics and their multilayer actuators has been explored.First,in terms of Na_(0.5)Bi_(0.5)TiO_(3)-based ceramic materials,the ...In this review,the evolution of high strain Na_(0.5)Bi_(0.5)TiO_(3)-based lead-free piezoceramics and their multilayer actuators has been explored.First,in terms of Na_(0.5)Bi_(0.5)TiO_(3)-based ceramic materials,the origin of high strain,the typical chemical modification methods of obtaining large strain and extrinsic factors affecting the large strain are discussed.Then it briefly summarizes the problems existing in Na_(0.5)Bi_(0.5)TiO_(3)-based ceramics for multilayer actuator applications.Strategies to optimize strain performance by means of microstructure control and phase structure design are also discussed.Thereafter,in terms of multilayer actuator,we describe its characteristics,applications and preparation process systematically,as well as the recent development of Na_(0.5)Bi_(0.5)TiO_(3)-based multilayer actuator.At last,perspectives on directions of following work and promising fields for the applications of the materials and their devices are presented.展开更多
基金supported by the National Key R&D Program of China(Grant No.2022YFB4600300)the National Natural Science Foundation of China(No.U22A20189,52175364)the China Scholarship Council(Grant No.202206290134)。
文摘Nd-Fe-B permanent magnets play a crucial role in energy conversion and electronic devices.The essential magnetic properties of Nd-Fe-B magnets,particularly coercivity and remanent magnetization,are significantly infuenced by the phase characteristics and microstructure.In this work,Nd-Fe-B magnets were manufactured using vacuum induction melting(VIM),laser directed energy deposition(LDED)and laser powder bed fusion(LPBF)technologies.Themicrostructure evolution and phase selection of Nd-Fe-B magnets were then clarified in detail.The results indicated that the solidification velocity(V)and cooling rate(R)are key factors in the phase selection.In terms of the VIM-casting Nd-Fe-B magnet,a large volume fraction of theα-Fe soft magnetic phase(39.7 vol.%)and Nd2Fe17Bxmetastable phase(34.7 vol.%)areformed due to the low R(2.3×10-1?C s-1),whereas only a minor fraction of the Nd2Fe14B hard magnetic phase(5.15 vol.%)is presented.For the LDED-processed Nd-Fe-B deposit,although the Nd2Fe14B hard magnetic phase also had a low value(3.4 vol.%)as the values of V(<10-2m s-1)and R(5.06×103?C s-1)increased,part of theα-Fe soft magnetic phase(31.7vol.%)is suppressed,and a higher volume of Nd2Fe17Bxmetastable phases(47.5 vol.%)areformed.As a result,both the VIM-casting and LDED-processed Nd-Fe-B deposits exhibited poor magnetic properties.In contrast,employing the high values of V(>10-2m s-1)and R(1.45×106?C s-1)in the LPBF process resulted in the substantial formation of the Nd2Fe14B hard magnetic phase(55.8 vol.%)directly from the liquid,while theα-Fe soft magnetic phase and Nd2Fe17Bxmetastable phase precipitation are suppressed in the LPBF-processed Nd-Fe-B magnet.Additionally,crystallographic texture analysis reveals that the LPBF-processedNd-Fe-B magnets exhibit isotropic magnetic characteristics.Consequently,the LPBF-processed Nd-Fe-B deposit,exhibiting a coercivity of 656 k A m-1,remanence of 0.79 T and maximum energy product of 71.5 k J m-3,achieved an acceptable magnetic performance,comparable to other additive manufacturing processed Nd-Fe-B magnets from MQP(Nd-lean)Nd-Fe-Bpowder.
基金supported by the Yunnan Fundamental Research Project(202301BF070001-009,KC-22222357)the Sichuan Science and Technology Program(2023NSFSC0990)the School of Materials Science and Engineering,Jiangsu Engineering Laboratory of Light-Electricity-Heat Energy-Converting Materials and Applications。
文摘Ternary strategy with a suitable third component is a successful strategy to improve the photovoltaic performance of organic solar cells(OSCs).Very recently,Y-series based giant molecule acceptors or oligomerized acceptors have emerged as promising materials for achieving highly efficient and stable binary OSCs,while application as third component for ternary OSCs is limited.Here a novelπ-extended giant dimeric acceptor,GDF,is developed based on central Y series core fusion and rigid BDT as linker,and then incorporated into the state-of-the-art PM1:PC6 system to construct ternary OSCs.The GDF has a near planar backbone,resulting in increasedπ-conjugation,excellent crystallinity,and good electron transport capacity.When GDF is introduced into the PM1:PC6 system,it ensues in a cascade like the lowest unoccupied molecular orbitals(LUMO)energy level alignment,a complementary absorption band with PM1 and PC6,higher and balanced hole and electron mobility,slightly smaller domain size,and a higher exciton dissociation probability for PM1:PC6:GDF(1:1.1:0.1)blend film.As a consequence,the PM1:PC6:GDF(1:1.1:0.1)ternary OSC achieves a champion PCE of 19.22%,with a significantly higher open-circuit voltage and short-circuit current density,compared to 18.45%for the PM1:PC6(1:1.2)binary OSC.Our findings show that employing aπ-extended giant dimeric acceptor as a third component significantly improves the photovoltaic performance of ternary OSCs.
文摘In the present study,the effects of process parameters(output voltage x,nitrogen flux l and specific strengthening time s)on the microstructure and wear resistance properties of TiN coatings prepared by electrospark deposition(ESD)were investigatedsystematically.The microstructure of the coatings was characterized for thickness(TOC),content of TiN(CON)and porosity(POC).A statistical model was developed to identify the significant factors affecting the microstructure and wear resistance of the coatings.The results show that the output voltage x and nitrogen flux l present significant effects on majority of the evaluation indexes such asTOC,friction coefficient(COF)and wear mass loss(Id),while the specific strengthening time s has a significant effect on POC and asmall effect on the other indexes.The optimal process parameters were obtained as follows:output voltage(x,60V),nitrogen flux(l,15L/min)and specific strengthening time(s,3min/cm2).The variation of wear mass loss(Id)by the variation of the outputvoltage(x)and nitrogen flux(l)is attributed to the change of wear mechanisms of TiN coatings.The main wear mechanism of TiNcoating prepared under optimal process parameters is micro-cutting wear accompanied by micro-fracture wear.
基金Project(2016YFB11000100)supported by the National Key Technologies R&D Program,ChinaProject(KP201611)supported by Research Fund of the State Key Laboratory of Solidification Processing(NWPU),ChinaProject(51475380)supported by the National Natural Science Foundation of China
文摘Laser additive manufacturing technology with powder feeding was employed to repair wrought Ti17titanium alloy with small surface defects.The microstructure,micro-hardness and room temperature tensile properties of laser additive repaired(LARed)specimen were investigated.The results show that,cellular substructures are observed in the laser deposited zone(LDZ),rather than the typicalαlaths morphology due to lack of enough subsequent thermal cycles.The cellular substructures lead to lower micro-hardness in the LDZ compared with the wrought substrate zone which consists of duplex microstructure.The tensile test results indicate that the tensile deformation process of the LARed specimen exhibits a characteristic of dramatic plastic strain heterogeneity and fracture in the laser repaired zone with a mixed dimple and cleavage mode.The tensile strength of the LARed specimen is slightly higher than that of the wrought specimen and the elongation of11.7%is lower.
基金Projects(51105311,51475380)supported by the National Natural Science Foundation of ChinaProject(2013AA031103)supported by the National High-Tech Research and Development Program of China
文摘The microstructure, microhardness and tensile properties of laser additive manufactured (LAM) Ti?5Al?2Sn?2Zr?4Mo?4Cr alloy were investigated. The result shows that the microstructure evolution is strongly affected by the thermal history of LAM process. Primary α (αp) with different morphologies, secondary α (αs) and martensite α' can be observed at different positions of the LAMed specimen. Annealing treatment can promote the precipitation of rib-like α phase or acicular α phase. As a result, it can increase or decrease the microhardness. The as-deposited L-direction and T-direction specimens contain the same phase constituent with different morphologies. The tensile properties of the as-deposited LAMed specimens are characterized of anisotropy. The L-direction specimen shows the character of low strength but high ductility when compared with the T-direction specimen. After annealing treatment, the strength of L-direction specimen increases significantly while the ductility reduces. The strength of the annealed T-direction specimen changes little, however, the ductility reduces nearly by 50%.
基金financially supported by the National Natural Science Foundation of China (Nos. 51922038 and 51672078)Hunan University State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Independent Research Project (No. 71675004)+1 种基金Hunan Youth Talents (2016RS3025)Hunan Natural Science Foundation (2016JJ3123)。
文摘To search for new cathode materials with high energy density of Lithium-ion batteries(LIBs) is one of the most challenging issues. Vanadium pentoxide(V2 O5) with high theoretical specific capacity is believed to be a promising candidate for the next generation cathode materials, yet still suffers from low lithium ion diffusion coefficient and poor electronic conductivity resulting in low cycling life and poor rate performances. Here, we report new large-scale carambola-like V2 O5 nanoflowers arrays anchored on microporous reed carbon as high performances LIBs cathode. Each individual pore space of the microporous reed carbon is like a hexagonal cylinder, and the area of each carbon wall is more than103 um2, which is favorable for the growth of V2 O5 nanostructure arrays. After hydrothermal, the largescale carambola-like V2 O5 nanoflowers arrays can directly grow on the surface of microporous carbon.Due to the novel composite structures, the V2 O5 nanoflowers arrays@microporous carbon stabilizes at273 mA h g^(-1) after 100 cycles at 0.2 C. When cycling at 1.0 C over 500 cycles, the capacity still maintains at 180 mAh g^(-1). The demonstrated approach in this work paves the way for the development of high rate capability and excellent cycling stability V2 O5-based cathode materials.
基金supported by the National Natural Science Foundation of China (51403178, 51573154)the Project of Hunan Natural Science Foundation (2018JJ2391, 2015JJ3113)the Scientific Research Fund of Hunan Provincial Education Department (14C1099, YB2015B025, 13A102)
文摘Two novel asymmetric organic small molecules of IT(2FBT-T3Cz)_2and IT(2FBT-TT3Cz)_2with an indenothiophene(IT)central donor core,fluorinated benzothiadiazole(2FBT)as acceptor and 3-carbazole(Cz)unit as terminal group were designed and synthesized as the donor materials in organic solar cells(OSCs).The thermal,optical absorption,electrochemical property,hole–electron mobility,film morphology were thoroughly studied.Using PC_(71)BM as an electron acceptor,without any additive and thermal annealing(TA)treatment,the IT(2FBT-T3Cz)_2-based cells showed a promising power conversion efficiency(PCE)of5.81%and the IT(2FBT-TT3Cz)_2-based cells exhibited a PCE of 4.39%.Our results demonstrate that the IT-based asymmetric small molecules can be developed as a promising class of donor materials for highperformance OSCs.
基金Supported by National Key Research and Development Program of China(2018YFD0100105-1)Earmarked Fund for China Agriculture Research System(nycytxgxcxtd)+2 种基金Science and Technology Major Project of Guangxi(Gui Ke AA17204064)Fundamental Research Funds of Guangxi Academy of Agricultural Sciences(Gui Nong Ke 2016YM42)Science and Technology Development Fund of Maize Research Institute,Guangxi Academy of Agricultural Sciences(Yu ZX2015001)
文摘Total 20 maize varieties were subjected to drought stress at flowering stage,and then the relative water content,soluble sugar content,chlorophyll content,malondialdehyde( MDA) content and superoxide dismutase( SOD) activity in their leaves,as well as their yields were determined. The drought tolerance of the physiological and biochemical indexes was scored by five-level scoring method,and the drought tolerance index was calculated by the yield index to comprehensively evaluate the drought tolerance of maize during flowering stage. The results showed that the scores of drought tolerance of the maize varieties ranged from 1. 929 3 to 5. 659 5. Among them,the scores of Zhengda 619,Guidan 162 and Guidan 0810 were greater than 5. 0,followed by Dika 008,Xianyu 30 T60,Xianzhengda 901,Qingnong 68,South America No. 1 and Wanchuan 1306 of which the scores were in the range of 4. 0-5. 0. The drought tolerance indexes were in the range of 0. 410 4-1. 096 3. Among the test maize varieties,the drought tolerance indexes of Guidan 0810,Pacific 99 and Zhengda 619 were greater than 1. 0,and those of Xianyu 30 T60,Dika 008 and South America No. 1 were in the range of 0. 9-1. 0. The correlation between the two kinds of evaluation results was 0. 588 7 and was extremely significant. The five-level scoring method and the drought tolerance index can be used simultaneously for the evaluation of drought tolerance of maize during flowering stage. The two aspects of evaluation results showed that Guidan 0810,Zhengda 619,Xianyu 30 T60,Dika 008 and South America No. 1 were drought-tolerant varieties,among which Guidan 0810 and Zhengda 619 were extremely highly drought-tolerant varieties.
基金National Key R&D Program of China(2018YFD0100105)Natural Science Foundation of Guangxi(2015GXNSFBA139061)+1 种基金Special Fund for Innovation-driven Development in Guangxi(Gui Ke AA17204064)Guangxi Innovative Team Construction Project of National Modern Agricultural Industrial Technology System(nycytxgxcxtd).
文摘Based on isobaric tags for relative and absolute quantification(iTRAQ)technology,the proteome of grains of a maize cultivar Huangzao 4 under drought stress at grain filling stage was analyzed.The results show that under drought stress,438 proteins were differentially expressed in the maize grains during grain filling.Among them,200 were up-regulated and 238 were down-regulated.The gene ontology(GO)analysis shows that the biological processes in which differential proteins are more involved are cellular processes,metabolic processes and single biological processes;proteins in the cell component category are mainly distributed in cells,cell parts and organelles;and the proteins the molecular function category mainly possess catalytic activity and binding function.Differentially expressed proteins classified by COG are mainly involved in protein post-translational modification and transport,molecular chaperones,general functional genes,translation,ribosomal structure,biosynthesis,energy production and transformation,carbohydrate transport and metabolism,amino acid transport and metabolism,etc.The subcellular structure of the differentially expressed proteins is mainly located in the cell chloroplast and cytosol.The proportions are 35.01%and 30.21%respectively.KEGG metabolic pathway enrichment analysis shows that the differentially expressed proteins are mostly involved in antibiotic biosynthesis,microbial metabolism in different environments,and endoplasmic reticulum protein processing;the metabolic pathways with higher enrichment are the carbon fixation pathway and estrogen signaling pathway of prokaryotes;and the higher enrichment and greater significance are in the tricarboxylic acid cycle,carbon fixation of photosynthetic organisms and proteasome.The results of this study preliminarily reveal the adaptive mechanism of maize grains in response to drought stress during grain filling,providing a theoretical reference for maize drought-resistant molecular breeding.
基金Key Research and Development Project of Guangxi(Gui Ke AB18221056)Guangxi Innovative Team Building Project in Earmarked Fund for China Agriculture Research System(nycytxgxcxtd-04-02)Special Fund for Innovation-driven Development in Guangxi(Gui Ke AA17204064)。
文摘[Objectives]This study aimed to explore the effect of different concentrations of selenium fertilizer on the yield,selenium content and heavy metal contents of waxy maize,thereby providing reference for the scientific application of selenium fertilizer on waxy maize.[Methods]Different varieties of waxy maize(Guitiannuo 611,Guinuo 615 and Guiheinuo 609)were used as test materials.They were sprayed with different concentrations(0,0.5,1.0,1.5 and 2.0 g/L)of water-soluble selenium fertilizer(Xinxibao)at the big flare stage,and the effect on the yield,selenium content and heavy metal contents of the waxy maize was analyzed.[Results]Foliar application of different concentrations of selenium fertilizer showed no significant effect on the yield and yield components of waxy maize.As the concentration of selenium fertilizer increased,the grain selenium content of different varieties of waxy maize increased.Among them,the increase of Guinuo 615 was the largest,of which the selenium content reached 0.265 mg/kg,2.82 times that of the control(water).The cadmium and arsenic contents of different varieties of waxy maize decreased with the increase of the concentration of selenium fertilizer sprayed.Among the waxy maize varieties,the cadmium and arsenic contents of Guitiannuo 611 dropped the most significantly,up to 52.94%and 77.78%.In waxy maize,the correlation coefficients between selenium content and cadmium,arsenic contents were-0.5509(P<0.05)and-0.8530(P<0.01),respectively.[Conclusions]Spraying exogenous selenium fertilizer had no obvious effect on the yield of waxy maize.However,the increase of the concentration of exogenous selenium fertilizer could significantly increase the selenium content and reduce the cadmium and arsenic contents in grains of different varieties of waxy maize.
基金supported by the National Key Research And Development Plan, China (No. 2016YFB1100100)the Research Fund of the State Key Laboratory of Solidification Processing (NWPU), China (No. KP201611)the National Natural Science Foundation of China (No. 51475380)
文摘Laser cladding deposited Ti-6Al-4V titanium alloy universally shows more complex microstructures,each of which has significant effect on mechanical properties. Of particular α/β interface phase has been observed in this paper under certain conditions. It demonstrates that the influence of the α/β interface phase on the tensile properties is closely associated with dislocations and twin substructure through comparison experiments. The results show that the α/β interface phase hinders dislocation motion and decreases effective slip length. In addition, the twin substructure has been activated in the α/β interface phase during tensile process and has acted somehow like grain boundaries. Therefore, the strength and the work-hardening rate of the laser cladding deposited Ti-6Al-4V titanium alloy have been significantly improved due to the dynamic Hall-Petch effect. Besides, the α/β interface phase leads to more uniform dislocations distribution, which implies that relative lower local concentrated stress will be produced along the α/β interface phase or colony boundary after the same amount of plastic deformation. Moreover,the twinning-induced plasticity effects in the α/β interface phase further increase the plastic deformation capacity. These results in higher elongation for the laser cladding deposited Ti-6Al-4V titanium alloy.It can be concluded that the current work suggests an effective method to simultaneously improve the strength and plasticity of laser cladding deposited Ti-6Al-4V titanium alloy based on the α/β interface phase.
基金Key Research and Development Projects of Shaanxi Province(No.2023-YBGY-359)China CEEC University Joint Education Project(2021108)+2 种基金Science and Technology Plan of Xi'an City(Nos.21ZCZZHXJS-QCY6-0001,21CXLHTJSGG-QCY8-0003)Open Fund of Key Laboratory of Plasma Dynamics of Air Force Engineering University(No.6142202210203)“Qin Chuang Yuan”Project of Shaanxi Province(No.2023KXJ-272).
文摘Improving the low-cycle fatigue(LCF)properties of additively manufactured Ti-5.6Al-3.8V alloy is critical in ensuring its service safety and represents a significant research challenge.This work discusses a so-lution that optimizes the alloy's microstructure and ductility by precisely controlling the over-saturated strengthening elements and heat treatment.This was accomplished using selective laser melting(SLM),heat treatment at 800 ℃ for 2 h,and furnace cooling on a Ti-5.6Al-3.8V alloy with tightly controlled Al,V,and O concentrations in a lower range.The results showed that the SLM-fabricated Ti-5.6Al-3.8V alloy,post-heat treatment,exhibited α laths with a width of~1.4 μm and β columnar grains with a diameter of~126 μm,without experiencing coarsening or variant selection phenomena.The alloy bal-anced strength and ductility post-heat treatment with a UTS of 1015 MPa and an EL of 16.5%relative to the as-deposited state(UTS of 1199 MPa and EL of 11.9%).Notably,the LCF properties of the heat-treated SLM Ti-5.6Al-3.8V alloy are superior to those of other Ti-6Al-4V alloys produced by additive manu-facturing and comparable to traditional forgings.At high strain amplitudes(1-1.5%),the fatigue life of this alloy was twice that of the Ti-6Al-4V forgings.Furthermore,we comprehensively analyzed the mi-crostructure,strength,and ductility of the SLM Ti-5.6Al-3.8V alloy to elucidate the factors influencing its LCF properties.These findings provide a solid foundation for improving the LCF properties of additively manufactured Ti-6Al-4V alloy,thereby contributing to its safe and reliable use in critical applications.
基金This work was supported by the Key Research and Development Projects of Shaanxi Province(2023-YBGY-359)the China CEEC University Joint Education Project(2021108)+1 种基金the Science and Technology Plan of Xi'an City(21ZCZZHXJS-QCY6-0001,21CXLHTJSGG-QCY8-0003)the Open Fund of Key Laboratory of Plasma Dynamics of Air Force Engineering University(6142202210203).
文摘Meeting the damage tolerance requirements for engineering-grade titanium alloys pose a significant challenge in achieving high fracture toughness in direct energy deposition(DED)titanium alloys.This work primarily investigated the relationship between the microstructure and the fracture toughness of DED new Ti-6Al-4V-1Mo alloy.Two types of microstructures were designed via two process strategies:high-line energy density(HE)and low-line energy density(LE).Relative to LE samples,HE samples possess larger-sized microstructural characteristics(coarser grain boundaryα(α_(GB)),largerαcolonies,and coarserαlaths).Lessα/βphase boundaries were formed by coarserαlaths in the HE samples,increasing the movement of dislocations,resulting in tensile strength decreasing from 1007.1 MPa(LE)to 930.8 MPa(HE)and elongation increasing from 10.8%(LE)to 15.7%(HE).Also,HE samples exhibited an excellent fracture toughness of 114.0 MPa m^(1/2),significantly higher than that of LE samples(76.8 MPa m^(1/2)).An analysis of crack propagation paths was conducted to investigate the factors contributing to toughening.The primary factor enhancing toughness is the frequent obstruction of cracks by coarseαGB and largeαcolonies in HE samples.Particularly,the pretty large-angle deflections induced by the superposition effect of coarseαGB and largeαcolonies play a vital of significant role.These factors induced the long and tortuous high-energy pathways,which resulted in ultimately improved fracture toughness.The discovered microstructural toughening mechanisms can serve as a reference for future studies involving titanium alloys,offering insights on how to enhance fracture toughness by achieving similar characteristics.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51105311 and 51475380)the National High Technology Research and Development Program of China (Grant No. 2013AA031103)
文摘Solidification microstructure of powder fed laser additive manufactured Ti-6Al--2Zr--2Sn--3Mo--1.5Cr--2Nb titanium alloy was investigated, The results showed that by deliberately increasing the powder feed rate, partially melted powders were retained at the top of the molten pool, which can promote heteroge- neous nucleus. Thus, each cladding layer is composed of two regions： （i） randomly orientated cellular structure region caused by partially melted powders at the top of each cladding layer; and （ii） epitaxial cellular structure region adjacent to the fusion line. Usually, randomly orientated cellular structure region was totally remelted for a wide range of process conditions. The remelting effect ensures the continuity of epitaxial growth of cellular structure and leads to the formation of columnar β grains, In order to obtain equiaxed grains the scanning velocity and powder feed rate should be carefully selected to enlarge the randomly orientated cellular structure region,
文摘The heterogeneous integration of photonic integrated circuits(PICs)with a diverse range of optoelectronic materials has emerged as a transformative approach,propelling photonic chips toward larger scales,superior performance,and advanced integration levels.Notably,two-dimensional(2D)materials,such as graphene,transition metal dichalcogenides(TMDCs),black phosphorus(BP),and hexagonal boron nitride(hBN),exhibit remarkable device performance and integration capabilities,offering promising potential for large-scale implementation in PICs.In this paper,we first present a comprehensive review of recent progress,systematically categorizing the integration of photonic circuits with 2D materials based on their types while also emphasizing their unique advantages.Then,we discuss the integration approaches of 2D materials with PICs.We also summarize the technical challenges in the heterogeneous integration of 2D materials in photonics and envision their immense potential for future applications in PICs.
基金This work was supported by grants from the National Natural Science Foundation of China(No.81471126 and No.81870868).
文摘Background:Cell salvage has recently been recommended for obstetric use in cases with a high risk of massive hemorrhage during cesarean section(CS).However,limited data are available to support the use of one suction device to collect lost blood.This study aimed to investigate the volume of red blood cells(RBCs)salvaged and the components of amniotic fluid(AF)in blood salvaged by one suction device or two devices during CS in patients with placenta previa and/or accrete.Methods:Thirty patients with placenta previa and/or accrete undergoing elective CS in the Women's Hospital of Zhejiang University School of Medicine were recruited for the present study from November 1,2017 to December 1,2018.The patients were randomly assigned to one of the two groups according to an Excel-generated random number sheet:Group 1(w=15),in which only one suction device was used to aspirate all blood and AF,and Group 2(w=15),in which a second suction device was mainly used to aspirate AF before the delivery of the placenta.Three samples of blood per patient(pre-wash,post-wash,and post-filtration)were collected to measure AF components.The salvaged RBC volumes were recorded.Continuous data of pre-wash,post-wash,and postfiltration samples were analyzed by using one-way analysis of variance with Tukey5s test for multiple comparisons,or Kruskal-Wallis test with Dunn test for multiple comparisons.Comparisons of continuous data between Group 1 and Group 2 were conducted using Student's t test or Mann-Whitney U test.Results:The salvaged RBC volume was significantly higher in Group 1 than that in Group 2(401.6±77.2 mL vs.330.1土53.3 mL,?=4.175,P<0.001).In both groups,squamous cells,lamellar bodies,and fat were significantly reduced by washing(all P<0.001)and squamous cells were further reduced by filtering(P<0.001).Squamous cells were found in six post-filtration samples(three from each group).Lamellar bodies and fat were completely removed by filtering.Insulin-like growth factor binding protein 1,alphafetoprotein,albumin,lactate dehydrogenase,and potassium were significantly reduced post-wash(all P<0.05),with no further significant reduction after filtration in either group(all P>0.05).The mean percentage of fetal RBCs post-filtration was(1.8±0.8)%with a range of 1.0%to 3.5%and(1.9±0.9)%with a range of 0.7%to 4.0%in Groups 1 and 2,respectively,showing no significant difference between the two groups(U=188.5,P=0.651).Conclusion:Cell salvage performed by one suction device could result in higher volume of salvaged RBCs and can be used safely for CS in patients with placenta previa and/or accrete when massive hemorrhage occurs.Trial registration number:ChiCTR-INR-17012926,http://www.chictr.org.cn/Chinese Clinical Trial Registry.
基金The authors are thankful to funds from the China Postdoctoral Science Foundation(No.RZ1900011127)Qingdao Innovation Leading Talent Program and Taishan Scholars Program and Natural Science Foundation of Shandong(No.ZR2017BEM028)+4 种基金M.S.is thankful to funds from the Science Foundation of Jiangsu Province(No.BK20171169)C.W.L.thanks the support from National Natural Science Foundation of China(No.51802168)China Postdoctoral Science Foundation(No.2018M630753)Natural Science Foundation of Shandong Province(No.ZR2018BEM006)Qingdao Postdoctoral Application Research Project.
文摘Aqueous Zinc-ion batteries(ZIBs),using zinc negative electrode and aqueous electrolyte,have attracted great attention in energy storage field due to the reliable safety and low-cost.A composite material comprised of VO2·0.2H2O nanocuboids anchored on graphene sheets(VOG)is synthesized through a facile and efficient microwave-assisted solvothermal strategy and is used as aqueous ZIBs cathode material.Owing to the synergistic effects between the high conductivity of graphene sheets and the desirable structural features of VO2·0.2H2O nanocuboids,the VOG electrode has excellent electronic and ionic transport ability,resulting in superior Zn ions storage performance.The Zn/VOG system delivers ultrahigh specific capacity of 423 mAh·g^−1 at 0.25 A·g^−1 and exhibits good cycling stability of up to 1,000 cycles at 8 A·g^−1 with 87%capacity retention.Systematical structural and elemental characterizations confirm that the interlayer space of VO2·0.2H2O nanocuboids can adapt to the reversible Zn ions insertion/extraction.The as-prepared VOG composite is a promising cathode material with remarkable electrochemical performance for low-cost and safe aqueous rechargeable ZIBs.
基金supported by the National Key Research and Development Program of China (No. 2018YFB1106302)the National Natural Science Foundation of China (Grant No. 51475380)the Aeronautical Science Foundation of China (Grant No. 2016ZE53)
文摘Thin-wall structures of Ti-6A1-4V were fabricated by low-power pulsed laser directed energy deposition. During deposition, consistent with prior reports, columnar grains were observed which grew from the bottom toward the top of melt pool tail. This resulted in a microstructure mainly composed of long and thin prior epitaxial β columnar grains (average width ^200μm). A periodic pattern in epitaxial growth of grains was observed, which was shown to depend upon laser traverse direction. Utilizing this, a novel means was proposed to determine accurately the fusion boundary of each deposited layer by inspection of the periodic wave patterns. As a result it was applied to investigate the influence of thermal cycling on microstructure evolution. Results showed that acicular martensite,α' phase, and a small amount of Widmanstatten, a laths, gradually converted to elongated acicular a and a large fraction of Widmanstatten a laths under layer-wise thermal cycling. Tensile tests showed that the yield strength, ultimate tensile strength and elongation of Ti-6Al-4V thin wall in the build direction were 9.1 %, 17.3% and 42% higher respectively than those typically observed in forged solids of the same alloy. It also showed the yield strength and ultimate tensile strength of the transverse tensile samples both were 13.3% higher than those from the build direction due to the strengthening effect of a large number of vertical β grain boundaries, but the elongation was 69.7% lower than that of the build direction due to the uneven grain deformation of β grains.
基金supported by the National Natural Science Foundation of China(Grant No.51475380)the National Key Research and Development Program of China(No.2018YFB1106302)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.3102020MS0402)the fund of the State Key Laboratory of Solidification Processing in NWPU(Grant No.SKLSP202110)。
文摘Although a variety of processing routes were developed to in-situ manipulate microstructure for fabricating high-performance Ti-6Al-4 V alloy by directed energy deposition(DED),the in-situ microstructural control ability has been limited and lead to a narrowed mechanical property control range.This work proved the microstructural correlation betweenβ-grains andα-laths resulting from the unique thermal characteristics of DED for the first time and solved such a dilemma through synchronous induction heating assisted laser deposition(SILD)technology.The results confirmed that the laser energy and inductive energy have a different effect on the solidification and solid phase transformation conditions.By adjusting the laser-induction parameters,the microstructural correlation can be tuned;theβ-grains andα-laths can be controlled relatively separately,thereby significantly enhancing the ductility of as-deposited sample(elongation from 14.2%to 20.1%).Furthermore,the mechanical properties of the tuned microstructures are even comparable to that of DED Ti-6Al-4 V with post heat treatment,which indicates that the potential of SILD to be a one-step manufacturing process to fabricate high performance components without post heat treatment.Furthermore,the tensile testing results of the tuned microstructures indicate thatα-lath size is more influential on the mechanical properties than theβ-grain size due to its stronger hindering effect on the slipping of dislocations.This work promotes the understanding of the microstructural formation mechanism in DED titanium alloy and proves that the combination of synchronous induction and laser can expand the ability to control the microstructure and properties of multi-layer deposition.
基金the support by the National Natural Science Foundation of China(No.U1732117,51902111 and 51672092)the China Postdoctoral Science Foundation(No.2019M662602)+1 种基金the Open Fund of Guangxi Key Laboratory of Information Materials(No.191015-K)the Donguan Innovative Research Team Program.
文摘In this review,the evolution of high strain Na_(0.5)Bi_(0.5)TiO_(3)-based lead-free piezoceramics and their multilayer actuators has been explored.First,in terms of Na_(0.5)Bi_(0.5)TiO_(3)-based ceramic materials,the origin of high strain,the typical chemical modification methods of obtaining large strain and extrinsic factors affecting the large strain are discussed.Then it briefly summarizes the problems existing in Na_(0.5)Bi_(0.5)TiO_(3)-based ceramics for multilayer actuator applications.Strategies to optimize strain performance by means of microstructure control and phase structure design are also discussed.Thereafter,in terms of multilayer actuator,we describe its characteristics,applications and preparation process systematically,as well as the recent development of Na_(0.5)Bi_(0.5)TiO_(3)-based multilayer actuator.At last,perspectives on directions of following work and promising fields for the applications of the materials and their devices are presented.
