This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction,neutron diffraction,and synchrotron X-ray tomography and the mechani...This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction,neutron diffraction,and synchrotron X-ray tomography and the mechanical properties of Al-Mg-Mn-Fe-Cu alloys.The findings reveal that the microstructures of the alloys consisted of an Al matrix,Al_(6)(FeMn),and Al_(2)CuMg phase particles.The addition of Fe significantly increased the yield strength(YS),and ultimate tensile strength(UTS)of the alloys,while reducing elongation.The transformation of the 3D morphology of the Al_(6)(FeMn)phase from separated and fine particles with Chinese-script morphology to interconnected rod-like structure as Fe content increased from 0.1%to 0.8%.This strengthening effect was attributed to the slip lines being blocked at the vicinity of the inter-connected Fe-rich phase,leading to grain rotation and dislocation density increment around the Fe-rich phase,ultimately improving the strength of the alloys.However,the Fe-rich phases and Al_(2)CuMg phases were found to be prone to cracking under tensile stress,resulting in decreased elongation of the alloys.This study provides a potential application in the design and manufacturing of new non-heat-treatable Al alloys for the automotive industry.展开更多
The next generation of synchrotron radiation light sources features extremely low emittance,enabling the generation of synchrotron radiation with significantly higher brilliance,which facilitates the exploration of ma...The next generation of synchrotron radiation light sources features extremely low emittance,enabling the generation of synchrotron radiation with significantly higher brilliance,which facilitates the exploration of matter at smaller scales.However,the extremely low emittance results in stronger sextupole magnet strengths,leading to high natural chromaticity.This necessitates the use of sextupole magnets to correct the natural chromaticity.For the Shanghai Synchrotron Radiation Facility Upgrade(SSRF-U),a lattice was designed for the storage ring that can achieve an ultra-low natural emittance of 72.2 pm·rad at the beam energy of 3.5 GeV.However,the significant detuning effects,driven by high second-order resonant driving terms due to strong sextupoles,will degrade the performance of the facility.To resolve this issue,installation of octupoles in the SSRF-U storage ring has been planned.This paper presents the study results on configuration selection and optimization method for the octupoles.An optimal solution for the SSRF-U storage ring was obtained to effectively mitigate the amplitude-dependent tune shift and the second-order chromaticity,consequently leading to an increased dynamic aperture(DA),momentum acceptance(MA),and reduced sensitivity to magnetic field errors.展开更多
As an advanced 4^(th) generation synchrotron radiation facility,the Shenzhen Innovation Light-source Facility(SILF)storage ring is based on multi-bend achromat(MBA)lattices,enabling one to two orders of magnitude redu...As an advanced 4^(th) generation synchrotron radiation facility,the Shenzhen Innovation Light-source Facility(SILF)storage ring is based on multi-bend achromat(MBA)lattices,enabling one to two orders of magnitude reduction in beam emittance compared to the 3^(rd) generation storage ring.This significantly enhance the radiation brightness and coherence.The multipole magnets of many types for SILF storage ring are under preliminary design,which require high integral field homogeneity.As a result,a dedicated pole tip optimization procedure with high efficiency is developed for quadrupole and sextupole magnets with Opera-2D^(■)python script.The procedure considers also the 3D field effect which makes the optimization more straightforward.In this paper,the design of the quadrupole and sextupole magnets for SILF storage ring is first presented,followed by a detailed description of the implemented pole shape optimization method.展开更多
Revised September 2013 with numbers verified by representatives of the synchrotrons （contact C.-J. Lin, LBNL）. For existing （future） neutrino beam lines the latest achieved （design） values are given.
We propose a photon-photon collider based on synchrotron gamma sources driven by relativistic electron beams in hollow plasma channels.The collimated(with a divergence angle of~1 mrad)and ultrabrilliant(>10^(28)pho...We propose a photon-photon collider based on synchrotron gamma sources driven by relativistic electron beams in hollow plasma channels.The collimated(with a divergence angle of~1 mrad)and ultrabrilliant(>10^(28)photons s^(-1)·mrad^(-2)·mm^(-2)per 0.1% bandwidth at 0.6 MeV)photon beams are generated by strong electromagnetic fields induced by current filamentation instability,and up to~10^(6) Breit-Wheeler(BW)pairs can be created per shot.Notably,the usage of hollow plasma channels not only enhances synchrotron radiation,but also allows flexible control of the produced photon beams,ensuring the alignment of the two colliding beams and maximizing the two-photon BW process.This setup has the advantage of a clean background by eliminating the yield from the nonlinear BW process,and the signal-to-noise ratio is higher than 10^(2).展开更多
Nano-scale chemical inhomogeneity in surface oxide films formed on a V-and N-containing martensite stainless steel and tempering heating induced changes are investigated by a combination of synchrotron-based hard X-ra...Nano-scale chemical inhomogeneity in surface oxide films formed on a V-and N-containing martensite stainless steel and tempering heating induced changes are investigated by a combination of synchrotron-based hard X-ray Photoelectron emission spectroscopy(HAXPES)and microscopy(HAXPEEM)as well as microscopic X-ray absorption spectroscopy(μ-XAS)techniques.The results reveal the inhomogeneity in the oxide films on the micron-sized Cr_(2)N-and VN-type particles,while the inhomogeneity on the martensite matrix phase exists due to localised formation of nano-sized tempering nitride particles at 600℃.The oxide film formed on Cr_(2)N-type particles is rich in Cr_(2)O_(3) compared with that on the martensite matrix and VN-type particles.With the increase of tempering temperature,Cr_(2)O_(3) formation is faster for the oxidation of Cr in the martensite matrix than the oxidation of Cr nitride-rich particles.展开更多
Stripping injection overcomes the limitations of Liouville's theorem and is widely used for beam injection and accumulation in high-intensity synchrotrons.The interaction between the stripping foil and beam is cru...Stripping injection overcomes the limitations of Liouville's theorem and is widely used for beam injection and accumulation in high-intensity synchrotrons.The interaction between the stripping foil and beam is crucial in the study of stripping injection,particularly in low-energy stripping injection synchrotrons,such as the XiPAF synchrotron.The foil thickness is the main parameter that affects the properties of the beam after injection.The thin stripping foil is reinforced with collodion during its installation.However,the collodion on the foil surface makes it difficult to determine its equivalent thickness,because the mechanical measurements are not sufficiently reliable or convenient for continuously determining foil thickness.We propose an online stripping foil thickness measurement method based on the ionization energy loss effect,which is suitable for any foil thickness and does not require additional equipment.Experimental studies were conducted using the XiPAF synchrotron.The limitation of this method was examined,and the results were verified by comparing the experimentally obtained beam current accumulation curves with the simulation results.This confirms the accuracy and reliability of the proposed method for measuring the stripping foil thickness.展开更多
Objective:The present study investigated the cytoprotective effects of a Pogonatherum paniceum extract prepared with 80%ethanol(PPE)using synchrotron radiation-based Fourier transform infrared(SR-FTIR)microspectroscop...Objective:The present study investigated the cytoprotective effects of a Pogonatherum paniceum extract prepared with 80%ethanol(PPE)using synchrotron radiation-based Fourier transform infrared(SR-FTIR)microspectroscopy and determined its phytochemical profile.Methods:The volatile and polyphenolic compounds in PPE were characterized using gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry,respectively.The antioxidant capacity of PPE was evaluated using chemical and cell-based assays.The SR-FTIR microspectroscopy was performed to evaluate the cytoprotective effect of PPE by identifying changes in macromolecule composition in tert-butyl hydroperoxide(t BuOOH)-induced oxidative damage in RAW264.7 cells.Results:A total of 48 volatile compounds and 28 polyphenol components were found in PPE.PPE exhibited a high potential for antioxidant activity by scavenging the intracellular reactive oxygen species in t Bu OOH-induced oxidative damage in RAW264.7 cells.PPE treatment also significantly protected RAW264.7 cells against t BuOOH-induced toxicity and restored cell viability.The SR-FTIR analysis revealed that t BuOOH increased the lipid and ester lipid content in RAW264.7 cells.The PPE exerted a cytoprotective effect by decreasing the levels of lipid and ester lipid compounds that had been elevated by t BuOOH in RAW264.7 cells.These findings indicate that PPE has cytoprotective potential due to its ability to inhibit endogenous reactive oxygen species.Conclusion:This study extends the current knowledge on the phytochemistry of PPE and its antioxidant and cytoprotective effects.These findings support the use of SR-FTIR microspectroscopy to determine the cytoprotective effects of natural products.PPE extract may be a candidate compound for new therapeutics and nutraceuticals that target the prevention of oxidative stress-associated diseases.展开更多
Columnar to equiaxial crystal transition(CET)is an important technological feature in many casting processes.This work investigated the CET during the solidification of Mg-Gd-Zn alloys by combining synchrotron radiati...Columnar to equiaxial crystal transition(CET)is an important technological feature in many casting processes.This work investigated the CET during the solidification of Mg-Gd-Zn alloys by combining synchrotron radiation in-situ imaging and phase-field method.Results show that the grain size,dendrite tip radius,and secondary dendrite arm spacing(SDAS)all exponentially decrease with an increase in cooling rate(Vc).The variation in the radius of the dendritic tip is similar to the prediction of the Hunt model,while the variation in the SDAS is close to the Bouchard-Kirkaldy model.It is worth noting that the CET is promoted by a decrease in the temperature gradient(G)and an increase in the cooling rate(Vc).In both equiaxed and columnar crystal regions,the dendrite tip growth rate and solid phase volume fraction increase with increasing G and Vc.In addition,the CET process has been predicted by simulation.The results are consistent with the predictions of the GTK model,which is important for the in-depth study of the dendrite morphology in different crystallization regions.In the final stage,the effects of different critical subcooling degrees and nucleation densities on the CET were explored.The results show that increasing the critical nucleation supercooling degree can inhibit the generation of equiaxial crystals,while increasing the nucleation density helps to promote the CET.展开更多
In this work,the microstructure evolution and mechanical behavior of extruded SiC/ZA63 Mg matrix composites are investigated via combined experimental study and three-dimensionalfinite element modelling(3D FEM)based on...In this work,the microstructure evolution and mechanical behavior of extruded SiC/ZA63 Mg matrix composites are investigated via combined experimental study and three-dimensionalfinite element modelling(3D FEM)based on the actual 3D microstructure achieved by synchrotron tomography.The results show that the average grain size of composite increases from 0.57μm of 8μm-SiC/ZA63 to 8.73μm of 50μm-SiC/ZA63.The type of texture transforms from the typicalfiber texture in 8μm-SiC/ZA63 to intense basal texture in 50μm-SiC/ZA63 composite and the intensity of texture increases sharply with increase of SiC particle size.The dynamic recrystallization(DRX)mechanism is also changed with increasing SiC particle size.Experimental and simulation results verify that the strength and elongation both decrease with increase of SiC particle size.The 8μm-SiC/ZA63 composite possesses the optimal mechanical property with yield strength(YS)of 383 MPa,ultimate tensile strength(UTS)of 424 MPa and elongation of 6.3%.The outstanding mechanical property is attributed to the ultrafine grain size,high-density precipitates and dislocation,good loading transfer effect and the interface bonding between SiC and matrix,as well as the weakened basal texture.The simulation results reveal that the micro-cracks tend to initiate at the interface between SiC and matrix,and then propagate along the interface between particle and Mg matrix or at the high strain and stress regions,and further connect with other micro-cracks.The main fracture mechanism in 8μm-SiC/ZA63 composite is ductile damage of matrix and interfacial debonding.With the increase of particle size,interface strength and particle strength decrease,and interface debonding and particle rupture become the main fracture mechanism in the 30μm-and 50μm-SiC/ZA63 composites.展开更多
Pyrrhotite naturally occurs in various superstructures including magnetic(4C)and non-magnetic(5C,6C)types,each with distinct physicochemical properties and flotation behaviors.Challenges in accurately identifying and ...Pyrrhotite naturally occurs in various superstructures including magnetic(4C)and non-magnetic(5C,6C)types,each with distinct physicochemical properties and flotation behaviors.Challenges in accurately identifying and quantifying these superstructures hinder the optimization of pyrrhotite depression in flotation processes.To address this critical issue,synchrotron X-ray powder diffraction(S-XRPD)with Rietveld refinement was employed to quantify the distribution of superstructures in the feed and flotation concentrates of a copper–gold ore.To elucidate the mechanisms influencing depression,density functional theory(DFT)calculations were conducted to explore the electronic structures and surface reactivity of the pyrrhotite superstructures toward the adsorption of water,oxygen and hydroxyl ions(OH-)as dominant species present in the flotation process.S-XRPD analysis revealed that flotation recovery rates of pyrrhotite followed the order of 4C<6C<5C.DFT calculations indicated that the Fe 3d and S 3p orbital band centers exhibited a similar trend relative to the Fermi level with 4C being the closest.The Fe3d band center suggested that the 4C structure possessed a more reactive surface toward the oxygen reduction reaction,promoting the formation of hydrophilic Fe-OH sites.The S 3p band center order also implied that xanthate on the non-magnetic 5C and 6C surfaces could oxidize to dixanthogen,increasing hydrophobicity and floatability,while 4C formed less hydrophobic metal-xanthate complexes.Adsorption energy and charge transfer analyses of water,hydroxyl ions and molecular oxygen further supported the high reactivity and hydrophilic nature of 4C pyrrhotite.The strong bonding with hydroxyl ions indicated enhanced surface passivation by hydrophilic Fe–OOH complexes,aligning with the experimentally observed flotation order(4C<6C<5C).These findings provide a compelling correlation between experimental flotation results and electronic structure calculations,delivering crucial insights for optimizing flotation processes and improving pyrrhotite depression.This breakthrough opens up new opportunities to enhance the efficiency of flotation processes in the mining industry.展开更多
Trace amounts of Zr and V can increase the recrystallization temperature of Al-Mg-Si wrought aluminum alloys,which is expected to regulate the recrystallization grain.In this paper,trace amounts of V and Zr were added...Trace amounts of Zr and V can increase the recrystallization temperature of Al-Mg-Si wrought aluminum alloys,which is expected to regulate the recrystallization grain.In this paper,trace amounts of V and Zr were added to recycled Al-Mg-Si alloys,and their e ffects on the microstructure and mechanical properties of the cast alloys were studied by scanning electron microscopy(SEM)and synchrotron radiation X-ray tomography(SRXT).The results show that the addition of Zr significantly increases the grain sizes due to the“Zr poisoning”;V addition has no significant effect on the grain size.The morphology of Fe-rich phase gradually changes from the large Chinese-script shape to the fine short rod and curved long strip shape,and the distribution uniformity is improved with the combined addition of V and Zr.The three-dimensional(3 D)morphology of Fe-rich phase includes granular,short rod-like,simple branch and multi-branch structures.The individual addition of V and Zr has no significant effect on the morphology of Fe-rich phase;but the combined addition of V and Zr significantly increases the number and volume fraction of Fe-rich phase with small size(diameter£15μm),the number of branches in the largest Fe-rich phase is significantly reduced,resulting in the improvement of elongation.This work provides a theoretical basis for the development of new recycled Al-Mg-Si alloys in industrial application.展开更多
Perovskite solar cells(PSC)are considered as a promising photovoltaic technology due to their low cost and high efficiency exceeding 26.8%.Ultra-lightweight flexible perovskite solar cells(FPSCs)can be applied to many...Perovskite solar cells(PSC)are considered as a promising photovoltaic technology due to their low cost and high efficiency exceeding 26.8%.Ultra-lightweight flexible perovskite solar cells(FPSCs)can be applied to many fields such as architecture and portable devices.Although the photovoltaic conversion efficiency(PCE)of FPSC has exceeded 24%in the past few years,further application of FPSC is constrained by the challenges posed by limitation of critical material components.Here,we discussed recent research progress of key FPSC materials,mechanical endurance,low-temperature fabrication,etc.With the advantages of high brightness,collimation and resolution,we specially introduced the application of synchrotron radiation grazing incidence wide-angle X-ray scattering(GIWAXS)to directly observe the perovskite buried interface structure and corresponding mechanical stability of FPSCs without any damage.Finally,we summarize the challenges and propose an outlook about the large-scale preparation of efficient and stable FPSC modules.展开更多
Laser powder bed fusion(LPBF)is used to fabricate complex-shaped,dense,and high-performance oxide ceramics.During LPBF,bubbles form and evolve in the melt pool and ultimately remain in the printed ceramics as pores,wh...Laser powder bed fusion(LPBF)is used to fabricate complex-shaped,dense,and high-performance oxide ceramics.During LPBF,bubbles form and evolve in the melt pool and ultimately remain in the printed ceramics as pores,which significantly degrade the mechanical properties.Therefore,it is essential to understand the bubble behaviors during LPBF.Herein,we conducted an in-situ investigation of the bubble dynamics in the melt pool of homogeneously mixed Al_(2)O_(3)-Y_(2)O_(3) powders using synchrotron high-speed X-ray imaging.The formation,growth,motion,and evolution of bubbles,as well as the relationship between the instability of melt flow and bubble rupture during LPBF,were elucidated.The findings reveal that bubbles from the interstices within the powder bed grow following three distinct modes,i.e.,uplift growth,gas channel attachment,and bubble coalescence.Furthermore,melt flow oscillations caused by the bursting of large bubbles can lead to local instability of the melt pool.Results from this study enhance the understanding of bubble dynamics during LPBF and may provide valuable insights for pore elimination in LPBF-processed oxide ceramics.展开更多
In the present study,a body-centered-cubic(BCC)structured Nb/TiNb multilayer nanocomposite with high yield strength,which comprises a soft TiNb matrix and reinforced Nb nanowires,was designed and fabricated with the a...In the present study,a body-centered-cubic(BCC)structured Nb/TiNb multilayer nanocomposite with high yield strength,which comprises a soft TiNb matrix and reinforced Nb nanowires,was designed and fabricated with the aim of elucidating the strengthening mechanism of Nb/TiNb multilayer nanocomposite by scanning electron microscope,transmission electron microscopy and in situ synchrotron X-ray diffraction.It is observed that the Nb/TiNb nanocomposite possesses a high yield strength of~640 MPa,significantly exceeding that of the conventional single-phaseβ-type Ti alloys.Further experimental results indicate that as plastic deformation commenced in the TiNb matrix of Nb/TiNb nanocomposite,load transfer from the soft TiNb matrix into the reinforced Nb nanowires occurred,allowing for a high load-bearing stress contribution and a significant strength enhancement of Nb/TiNb nanocomposite.Meanwhile,the embedded Nb nanowires can effectively impede the propagation of dislocation in TiNb matrix,further strengthening the present nanocomposite.These findings elucidate the strengthening mechanism of Nb/TiNb nanocomposite through the above two combinations,providing a basis for the design and development of the high-strength composites with a single-phase BCC structure for biomedical applications.展开更多
Controlling the morphology of Al_(2) Cu intermetallic compounds(IMCs)has been of importance to enhance the properties of Al-based alloys.However,the quantification of Al_(2) Cu IMCs with diversified morphologies is st...Controlling the morphology of Al_(2) Cu intermetallic compounds(IMCs)has been of importance to enhance the properties of Al-based alloys.However,the quantification of Al_(2) Cu IMCs with diversified morphologies is still lacking,and the morphological evolution of Al_(2) Cu dendrites remains poorly understood.Using synchrotron X-ray tomography,we have directly quantified the morphological evolution of proeutectic Al_(2) Cu IMCs in directionally solidified Al-Cu alloys.The three-dimensional(3D)morphologies of Al_(2) Cu IMCs under different growth rates were quantified using volume,specific surface area,interconnectivity,tortuosity,and Gaussian curvature.The faceted morphology under slow growth rate was divided into three different types,including single hollow prism,irregular prism lacking partial faces,and coalesced prism consisting of two adjacent crystals.The morphological transition from faceted prism to non-faceted algae-like,irregular tree-like,and typically dendritic shapes with increasing growth rates was determined,reflecting the growth modes varied from lateral mode to intermediary and continuous modes.The non-faceted Al_(2) Cu dendrite had one primary stem,three groups of secondary arms,and a faceted tip.The angles between secondary arms were 120°,and the tip consisted of(011)and(011^(-))planes.This work provides a deep understanding of the formation and growth of complex IMCs in metallic alloys.展开更多
Lithium-and manganese-rich(LMR)oxide cathode materials are among the most attractive candidates for next-generation energy-storage materials owing to their anomalous capacity.However,severe Mn dissolution that occurs ...Lithium-and manganese-rich(LMR)oxide cathode materials are among the most attractive candidates for next-generation energy-storage materials owing to their anomalous capacity.However,severe Mn dissolution that occurs during long-term cycling,which leads to capacity loss,hinders their application prospects.In this study,nanoscale AlPO_(4)-coated Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LMR@APO)with significantly enhanced electrochemical performance is successfully synthesized using a simple and effective sol–gel method to mitigate Mn dissolution and suppress local structural distortion at high voltages.Because of the complex evolution of the structure and oxidation state of LMR materials during electrochemical cycling,observing and analyzing them using traditional single characterization methods may be difficult.Therefore,we combine various synchrotron-based characterization techniques to conduct a detailed analysis of the electronic and coordination structures of the cathode material from the surface to the bulk.Synchrotron-based hard and soft X-ray spectroscopies are integrated to investigate the differences in O and Mn evolution between the surfaces and bulk of the cathode.Advanced synchrotron-based transmission X-ray microscopy combined with X-ray near-edge absorption-structure technology is utilized to visualize the two-dimensional nanometer-scale reactivity of the LMR cathode.The AlPO_(4)-coating layer can stabilize the surface structure of the LMR material,effectively alleviating irreversible oxygen release on the surface and preventing the dissolution of Mn^(2+)at the interface caused by side reactions after a long cycle.Therefore,the spatial reaction uniformity of Mn is enhanced by the AlPO_(4)-coating layer,and rapid capacity decay caused by Mn deactivation is prevented.The AlPO_(4)-coating method is a facile modification strategy for high-performance LMR materials.展开更多
The deformation mechanism of glycerol plasticized poly(vinyl alcohol)(PVA)with different hydrolyses(88%,92%,98%)at elevated temperatures(60-100℃)was elucidated by in situ synchrotron radiation X-ray scattering.The vi...The deformation mechanism of glycerol plasticized poly(vinyl alcohol)(PVA)with different hydrolyses(88%,92%,98%)at elevated temperatures(60-100℃)was elucidated by in situ synchrotron radiation X-ray scattering.The vinyl acetate(VAc)in PVA acts as a non-crystalline chain defect,which significantly influences the plastic deformation and stretching-induced crystallization behavior of PVA.The key microstructural parameters of PVA during deformation,such as crystallinity(χ_(c)),lateral crystallite size(L),and long period(l),in combination with the stress-strain curves,were obtained.The experimental results show that the deformation process of the plasticized PVA film present a three-stage evolution:(i)a plastic deformation zone.The plastic deformation of the crystallite occurs as evidenced by the apparent decrease in crystallinity and lamellar reorientation induced by stretching;(ii)the stress softening zone.The decreasing trend of crystallinity becomes slow,and the long period becomes smaller,which indicates that PVA crystallization is induced by stretching;and(iii)the strain-hardening zone.There is a synergistic effect between the crystallite destruction and formation.Further research reveals that a high temperature and low degree of alcoholysis favor the stretching-induced crystallization of PVA,while the system with a high degree of alcoholysis shows significant characteristics of preferred crystal growth.展开更多
The water drop penetration time(WDPT)test consists of placing water drops on a material's surface in order to evaluate how long it takes to penetrate the pores.It is used to evaluate the hydrophobicity of material...The water drop penetration time(WDPT)test consists of placing water drops on a material's surface in order to evaluate how long it takes to penetrate the pores.It is used to evaluate the hydrophobicity of materials.This study aims at investigating in more detail the soil-water interaction during the test,exposing its mechanism.For that,a model soil named Hamburg Sand was coated with a hydrophobic fluoropolymer and then a WDPT test was performed while computed tomography(CT)images were taken.Tomography experiments were performed at the P07 high-energy materials science(HEMS)beamline,operated by Helmholtz–Zentrum Hereon,at the storage ring PETRA III at the Deutsches Elektronen-Synchrotron(DESY)in Hamburg.Using synchrotron radiation,a tomogram can be obtained in about 10 min,way less time than regular laboratory X-ray sources usually owned by universities.The faster imaging enables the observation of the drop penetration during time and thus provides insight into the dynamics of the process.After that,digital discrete image correlation is performed to track the displacement of the grains throughout time.From the results one can observe that,as the drop is absorbed at the material's surface,the grains directly around the droplet base are dragged to the liquid-air interface around the drop,revealing grain kinematics during capillary interactions of the penetrating liquid and sand grains.展开更多
Magnetic alloy（MA）-loaded cavities have been widely used in compact proton and heavy-ion synchrotrons,and the MA core is the key issue in their development.Chinese-produced MA has never yet been adopted as core mate...Magnetic alloy（MA）-loaded cavities have been widely used in compact proton and heavy-ion synchrotrons,and the MA core is the key issue in their development.Chinese-produced MA has never yet been adopted as core material for an MA-loaded cavity.To use Chinese-produced MA as the core material,it is necessary to study its properties,and compare with MA material produced elsewhere.In this paper,the properties of several MA cores made of Chinese-produced material are measured.Based on the measured results,a schematic design is produced for a cavity which could obtain 1 kV gap voltage with less than 1.5 kW power dissipation in the frequency range of0.5-7 MHz.The difference between resonant frequencies obtained from simulation and analytical results is less than10%.展开更多
基金support from the Natural Science Foundation of China(Nos.52104373,52074131,and 51974092)the Basic and Applied Basic Foundation of Guangdong Province(No.2020B1515120065)。
文摘This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction,neutron diffraction,and synchrotron X-ray tomography and the mechanical properties of Al-Mg-Mn-Fe-Cu alloys.The findings reveal that the microstructures of the alloys consisted of an Al matrix,Al_(6)(FeMn),and Al_(2)CuMg phase particles.The addition of Fe significantly increased the yield strength(YS),and ultimate tensile strength(UTS)of the alloys,while reducing elongation.The transformation of the 3D morphology of the Al_(6)(FeMn)phase from separated and fine particles with Chinese-script morphology to interconnected rod-like structure as Fe content increased from 0.1%to 0.8%.This strengthening effect was attributed to the slip lines being blocked at the vicinity of the inter-connected Fe-rich phase,leading to grain rotation and dislocation density increment around the Fe-rich phase,ultimately improving the strength of the alloys.However,the Fe-rich phases and Al_(2)CuMg phases were found to be prone to cracking under tensile stress,resulting in decreased elongation of the alloys.This study provides a potential application in the design and manufacturing of new non-heat-treatable Al alloys for the automotive industry.
文摘The next generation of synchrotron radiation light sources features extremely low emittance,enabling the generation of synchrotron radiation with significantly higher brilliance,which facilitates the exploration of matter at smaller scales.However,the extremely low emittance results in stronger sextupole magnet strengths,leading to high natural chromaticity.This necessitates the use of sextupole magnets to correct the natural chromaticity.For the Shanghai Synchrotron Radiation Facility Upgrade(SSRF-U),a lattice was designed for the storage ring that can achieve an ultra-low natural emittance of 72.2 pm·rad at the beam energy of 3.5 GeV.However,the significant detuning effects,driven by high second-order resonant driving terms due to strong sextupoles,will degrade the performance of the facility.To resolve this issue,installation of octupoles in the SSRF-U storage ring has been planned.This paper presents the study results on configuration selection and optimization method for the octupoles.An optimal solution for the SSRF-U storage ring was obtained to effectively mitigate the amplitude-dependent tune shift and the second-order chromaticity,consequently leading to an increased dynamic aperture(DA),momentum acceptance(MA),and reduced sensitivity to magnetic field errors.
文摘As an advanced 4^(th) generation synchrotron radiation facility,the Shenzhen Innovation Light-source Facility(SILF)storage ring is based on multi-bend achromat(MBA)lattices,enabling one to two orders of magnitude reduction in beam emittance compared to the 3^(rd) generation storage ring.This significantly enhance the radiation brightness and coherence.The multipole magnets of many types for SILF storage ring are under preliminary design,which require high integral field homogeneity.As a result,a dedicated pole tip optimization procedure with high efficiency is developed for quadrupole and sextupole magnets with Opera-2D^(■)python script.The procedure considers also the 3D field effect which makes the optimization more straightforward.In this paper,the design of the quadrupole and sextupole magnets for SILF storage ring is first presented,followed by a detailed description of the implemented pole shape optimization method.
文摘Revised September 2013 with numbers verified by representatives of the synchrotrons （contact C.-J. Lin, LBNL）. For existing （future） neutrino beam lines the latest achieved （design） values are given.
基金supported by the Fund of the National Key Laboratory of Plasma Physics(Grant No.6142A04230204)the National Natural Science Foundation of China(Project No.12075046).
文摘We propose a photon-photon collider based on synchrotron gamma sources driven by relativistic electron beams in hollow plasma channels.The collimated(with a divergence angle of~1 mrad)and ultrabrilliant(>10^(28)photons s^(-1)·mrad^(-2)·mm^(-2)per 0.1% bandwidth at 0.6 MeV)photon beams are generated by strong electromagnetic fields induced by current filamentation instability,and up to~10^(6) Breit-Wheeler(BW)pairs can be created per shot.Notably,the usage of hollow plasma channels not only enhances synchrotron radiation,but also allows flexible control of the produced photon beams,ensuring the alignment of the two colliding beams and maximizing the two-photon BW process.This setup has the advantage of a clean background by eliminating the yield from the nonlinear BW process,and the signal-to-noise ratio is higher than 10^(2).
基金supported by the Vinnova(project number 2020-03778)supported by the Swedish Research Council(Vetenskapsradet,project number 2021-04157).
文摘Nano-scale chemical inhomogeneity in surface oxide films formed on a V-and N-containing martensite stainless steel and tempering heating induced changes are investigated by a combination of synchrotron-based hard X-ray Photoelectron emission spectroscopy(HAXPES)and microscopy(HAXPEEM)as well as microscopic X-ray absorption spectroscopy(μ-XAS)techniques.The results reveal the inhomogeneity in the oxide films on the micron-sized Cr_(2)N-and VN-type particles,while the inhomogeneity on the martensite matrix phase exists due to localised formation of nano-sized tempering nitride particles at 600℃.The oxide film formed on Cr_(2)N-type particles is rich in Cr_(2)O_(3) compared with that on the martensite matrix and VN-type particles.With the increase of tempering temperature,Cr_(2)O_(3) formation is faster for the oxidation of Cr in the martensite matrix than the oxidation of Cr nitride-rich particles.
文摘Stripping injection overcomes the limitations of Liouville's theorem and is widely used for beam injection and accumulation in high-intensity synchrotrons.The interaction between the stripping foil and beam is crucial in the study of stripping injection,particularly in low-energy stripping injection synchrotrons,such as the XiPAF synchrotron.The foil thickness is the main parameter that affects the properties of the beam after injection.The thin stripping foil is reinforced with collodion during its installation.However,the collodion on the foil surface makes it difficult to determine its equivalent thickness,because the mechanical measurements are not sufficiently reliable or convenient for continuously determining foil thickness.We propose an online stripping foil thickness measurement method based on the ionization energy loss effect,which is suitable for any foil thickness and does not require additional equipment.Experimental studies were conducted using the XiPAF synchrotron.The limitation of this method was examined,and the results were verified by comparing the experimentally obtained beam current accumulation curves with the simulation results.This confirms the accuracy and reliability of the proposed method for measuring the stripping foil thickness.
基金supported by the Basic Research Fund from Thailand Science Research and Innovation through Sisaket Rajabhat University(grant number:FF.13/2564)。
文摘Objective:The present study investigated the cytoprotective effects of a Pogonatherum paniceum extract prepared with 80%ethanol(PPE)using synchrotron radiation-based Fourier transform infrared(SR-FTIR)microspectroscopy and determined its phytochemical profile.Methods:The volatile and polyphenolic compounds in PPE were characterized using gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry,respectively.The antioxidant capacity of PPE was evaluated using chemical and cell-based assays.The SR-FTIR microspectroscopy was performed to evaluate the cytoprotective effect of PPE by identifying changes in macromolecule composition in tert-butyl hydroperoxide(t BuOOH)-induced oxidative damage in RAW264.7 cells.Results:A total of 48 volatile compounds and 28 polyphenol components were found in PPE.PPE exhibited a high potential for antioxidant activity by scavenging the intracellular reactive oxygen species in t Bu OOH-induced oxidative damage in RAW264.7 cells.PPE treatment also significantly protected RAW264.7 cells against t BuOOH-induced toxicity and restored cell viability.The SR-FTIR analysis revealed that t BuOOH increased the lipid and ester lipid content in RAW264.7 cells.The PPE exerted a cytoprotective effect by decreasing the levels of lipid and ester lipid compounds that had been elevated by t BuOOH in RAW264.7 cells.These findings indicate that PPE has cytoprotective potential due to its ability to inhibit endogenous reactive oxygen species.Conclusion:This study extends the current knowledge on the phytochemistry of PPE and its antioxidant and cytoprotective effects.These findings support the use of SR-FTIR microspectroscopy to determine the cytoprotective effects of natural products.PPE extract may be a candidate compound for new therapeutics and nutraceuticals that target the prevention of oxidative stress-associated diseases.
基金financially supported by the Postdoctoral Research Project of Henan Province(No.202101003)the Key Research Programs of Higher Education Institutions in Henan Province(Nos.24A450003,23A460016)+2 种基金the Henan Provincial Key Laboratory of Intelligent Manufacturing of Machinery and Equipment Open Subjects(No.IM202308)the Zhengzhou University of Light Industry Doctoral Research Initiation Fund(No.2019BSJJ005)the Henan Provincial Science and Technology Tackling Project(No.23A460016).
文摘Columnar to equiaxial crystal transition(CET)is an important technological feature in many casting processes.This work investigated the CET during the solidification of Mg-Gd-Zn alloys by combining synchrotron radiation in-situ imaging and phase-field method.Results show that the grain size,dendrite tip radius,and secondary dendrite arm spacing(SDAS)all exponentially decrease with an increase in cooling rate(Vc).The variation in the radius of the dendritic tip is similar to the prediction of the Hunt model,while the variation in the SDAS is close to the Bouchard-Kirkaldy model.It is worth noting that the CET is promoted by a decrease in the temperature gradient(G)and an increase in the cooling rate(Vc).In both equiaxed and columnar crystal regions,the dendrite tip growth rate and solid phase volume fraction increase with increasing G and Vc.In addition,the CET process has been predicted by simulation.The results are consistent with the predictions of the GTK model,which is important for the in-depth study of the dendrite morphology in different crystallization regions.In the final stage,the effects of different critical subcooling degrees and nucleation densities on the CET were explored.The results show that increasing the critical nucleation supercooling degree can inhibit the generation of equiaxial crystals,while increasing the nucleation density helps to promote the CET.
基金supported by the National Natural Science Foundation of China[51974058,52371005,52022017,51927801]the Fundamental Research Funds for the Central Universities(DUT23YG104).
文摘In this work,the microstructure evolution and mechanical behavior of extruded SiC/ZA63 Mg matrix composites are investigated via combined experimental study and three-dimensionalfinite element modelling(3D FEM)based on the actual 3D microstructure achieved by synchrotron tomography.The results show that the average grain size of composite increases from 0.57μm of 8μm-SiC/ZA63 to 8.73μm of 50μm-SiC/ZA63.The type of texture transforms from the typicalfiber texture in 8μm-SiC/ZA63 to intense basal texture in 50μm-SiC/ZA63 composite and the intensity of texture increases sharply with increase of SiC particle size.The dynamic recrystallization(DRX)mechanism is also changed with increasing SiC particle size.Experimental and simulation results verify that the strength and elongation both decrease with increase of SiC particle size.The 8μm-SiC/ZA63 composite possesses the optimal mechanical property with yield strength(YS)of 383 MPa,ultimate tensile strength(UTS)of 424 MPa and elongation of 6.3%.The outstanding mechanical property is attributed to the ultrafine grain size,high-density precipitates and dislocation,good loading transfer effect and the interface bonding between SiC and matrix,as well as the weakened basal texture.The simulation results reveal that the micro-cracks tend to initiate at the interface between SiC and matrix,and then propagate along the interface between particle and Mg matrix or at the high strain and stress regions,and further connect with other micro-cracks.The main fracture mechanism in 8μm-SiC/ZA63 composite is ductile damage of matrix and interfacial debonding.With the increase of particle size,interface strength and particle strength decrease,and interface debonding and particle rupture become the main fracture mechanism in the 30μm-and 50μm-SiC/ZA63 composites.
基金supported by the Australian Research Council Linkage Project(No.LP200200717)co sponsored by Newmont Corporation(United States)and Vega Industries(India)+1 种基金the Powder Diffraction Beamline at the Australia’s Nuclear Science and Technology Organisation(No.PDR19870),Australiathe Centre for Microscopy and Microanalysis at the University of Queensland(No.1366),Australia。
文摘Pyrrhotite naturally occurs in various superstructures including magnetic(4C)and non-magnetic(5C,6C)types,each with distinct physicochemical properties and flotation behaviors.Challenges in accurately identifying and quantifying these superstructures hinder the optimization of pyrrhotite depression in flotation processes.To address this critical issue,synchrotron X-ray powder diffraction(S-XRPD)with Rietveld refinement was employed to quantify the distribution of superstructures in the feed and flotation concentrates of a copper–gold ore.To elucidate the mechanisms influencing depression,density functional theory(DFT)calculations were conducted to explore the electronic structures and surface reactivity of the pyrrhotite superstructures toward the adsorption of water,oxygen and hydroxyl ions(OH-)as dominant species present in the flotation process.S-XRPD analysis revealed that flotation recovery rates of pyrrhotite followed the order of 4C<6C<5C.DFT calculations indicated that the Fe 3d and S 3p orbital band centers exhibited a similar trend relative to the Fermi level with 4C being the closest.The Fe3d band center suggested that the 4C structure possessed a more reactive surface toward the oxygen reduction reaction,promoting the formation of hydrophilic Fe-OH sites.The S 3p band center order also implied that xanthate on the non-magnetic 5C and 6C surfaces could oxidize to dixanthogen,increasing hydrophobicity and floatability,while 4C formed less hydrophobic metal-xanthate complexes.Adsorption energy and charge transfer analyses of water,hydroxyl ions and molecular oxygen further supported the high reactivity and hydrophilic nature of 4C pyrrhotite.The strong bonding with hydroxyl ions indicated enhanced surface passivation by hydrophilic Fe–OOH complexes,aligning with the experimentally observed flotation order(4C<6C<5C).These findings provide a compelling correlation between experimental flotation results and electronic structure calculations,delivering crucial insights for optimizing flotation processes and improving pyrrhotite depression.This breakthrough opens up new opportunities to enhance the efficiency of flotation processes in the mining industry.
基金Project(2024YEE0109100) supported by the National Key R&D Program of ChinaProjects(52074131,52104373) supported by the National Natural Science Foundation of ChinaProjects(2022YFJH001,2024YFJH001) supported by the Science and Technology Plan Program of Qingyuan City,China。
文摘Trace amounts of Zr and V can increase the recrystallization temperature of Al-Mg-Si wrought aluminum alloys,which is expected to regulate the recrystallization grain.In this paper,trace amounts of V and Zr were added to recycled Al-Mg-Si alloys,and their e ffects on the microstructure and mechanical properties of the cast alloys were studied by scanning electron microscopy(SEM)and synchrotron radiation X-ray tomography(SRXT).The results show that the addition of Zr significantly increases the grain sizes due to the“Zr poisoning”;V addition has no significant effect on the grain size.The morphology of Fe-rich phase gradually changes from the large Chinese-script shape to the fine short rod and curved long strip shape,and the distribution uniformity is improved with the combined addition of V and Zr.The three-dimensional(3 D)morphology of Fe-rich phase includes granular,short rod-like,simple branch and multi-branch structures.The individual addition of V and Zr has no significant effect on the morphology of Fe-rich phase;but the combined addition of V and Zr significantly increases the number and volume fraction of Fe-rich phase with small size(diameter£15μm),the number of branches in the largest Fe-rich phase is significantly reduced,resulting in the improvement of elongation.This work provides a theoretical basis for the development of new recycled Al-Mg-Si alloys in industrial application.
基金supported by Photon Science Research Center For Carbon Dioxide,Project of the National Natural Science Foundation of China(22332003)supported by the National Natural Science Foundation of China(12175298,12075309)+10 种基金the National Natural Science Foundation of China(62404176)Shanghai Science and Technology Innovation Action Plan(22JC1403800)Shanghai Municipal Science and Technology Commission(23JC1403300)2022 Self Deployed Instrument Design Project of Shanghai Advanced Research Institutethe Research Grant from the Shanghai Sailing Program(17YF1423700)Shanghai Municipal Commission for Science and Technology(20ZR1464100)Youth Innovation Promotion Association CAS(2021284)Fudan University Talent Introduction Projectthe support from the China Postdoctoral Science Foundation(2023M742732)the Postdoctoral Fellowship Program of CPSF(GZC20241303)the Fundamental Research Funds for the Central Universities(XJSJ24100)。
文摘Perovskite solar cells(PSC)are considered as a promising photovoltaic technology due to their low cost and high efficiency exceeding 26.8%.Ultra-lightweight flexible perovskite solar cells(FPSCs)can be applied to many fields such as architecture and portable devices.Although the photovoltaic conversion efficiency(PCE)of FPSC has exceeded 24%in the past few years,further application of FPSC is constrained by the challenges posed by limitation of critical material components.Here,we discussed recent research progress of key FPSC materials,mechanical endurance,low-temperature fabrication,etc.With the advantages of high brightness,collimation and resolution,we specially introduced the application of synchrotron radiation grazing incidence wide-angle X-ray scattering(GIWAXS)to directly observe the perovskite buried interface structure and corresponding mechanical stability of FPSCs without any damage.Finally,we summarize the challenges and propose an outlook about the large-scale preparation of efficient and stable FPSC modules.
基金financially supported by the National Science Fund for Distinguished Young Scholars,China(No.52325407)the Key Program of the National Natural Science Foundation of China(No.52234010)。
文摘Laser powder bed fusion(LPBF)is used to fabricate complex-shaped,dense,and high-performance oxide ceramics.During LPBF,bubbles form and evolve in the melt pool and ultimately remain in the printed ceramics as pores,which significantly degrade the mechanical properties.Therefore,it is essential to understand the bubble behaviors during LPBF.Herein,we conducted an in-situ investigation of the bubble dynamics in the melt pool of homogeneously mixed Al_(2)O_(3)-Y_(2)O_(3) powders using synchrotron high-speed X-ray imaging.The formation,growth,motion,and evolution of bubbles,as well as the relationship between the instability of melt flow and bubble rupture during LPBF,were elucidated.The findings reveal that bubbles from the interstices within the powder bed grow following three distinct modes,i.e.,uplift growth,gas channel attachment,and bubble coalescence.Furthermore,melt flow oscillations caused by the bursting of large bubbles can lead to local instability of the melt pool.Results from this study enhance the understanding of bubble dynamics during LPBF and may provide valuable insights for pore elimination in LPBF-processed oxide ceramics.
基金supported by the National Natural Science Foundation of China(Nos.51771082,51971009 and 52175410)Zhenjiang Science and Technology Program(No.GY2020001)+2 种基金the Six Talent Peaks Project in Jiangsu Province(No.2019-XCL-113)the Project of Faculty of Agricultural Equipment of Jiangsu University(No.NZXB20200101)Advanced Photon Source,a US Department of Energy(DOE)Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No.DE-AC02-06CH11357.
文摘In the present study,a body-centered-cubic(BCC)structured Nb/TiNb multilayer nanocomposite with high yield strength,which comprises a soft TiNb matrix and reinforced Nb nanowires,was designed and fabricated with the aim of elucidating the strengthening mechanism of Nb/TiNb multilayer nanocomposite by scanning electron microscope,transmission electron microscopy and in situ synchrotron X-ray diffraction.It is observed that the Nb/TiNb nanocomposite possesses a high yield strength of~640 MPa,significantly exceeding that of the conventional single-phaseβ-type Ti alloys.Further experimental results indicate that as plastic deformation commenced in the TiNb matrix of Nb/TiNb nanocomposite,load transfer from the soft TiNb matrix into the reinforced Nb nanowires occurred,allowing for a high load-bearing stress contribution and a significant strength enhancement of Nb/TiNb nanocomposite.Meanwhile,the embedded Nb nanowires can effectively impede the propagation of dislocation in TiNb matrix,further strengthening the present nanocomposite.These findings elucidate the strengthening mechanism of Nb/TiNb nanocomposite through the above two combinations,providing a basis for the design and development of the high-strength composites with a single-phase BCC structure for biomedical applications.
基金supported by the National Natural Science Foundation of China-Outstanding Young Scholars(No.52325407)the National Natural Science Foundation of China(No.51904187)+1 种基金the Project funded by China Postdoctoral Science Foundation(No.2022M712919)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515140124).
文摘Controlling the morphology of Al_(2) Cu intermetallic compounds(IMCs)has been of importance to enhance the properties of Al-based alloys.However,the quantification of Al_(2) Cu IMCs with diversified morphologies is still lacking,and the morphological evolution of Al_(2) Cu dendrites remains poorly understood.Using synchrotron X-ray tomography,we have directly quantified the morphological evolution of proeutectic Al_(2) Cu IMCs in directionally solidified Al-Cu alloys.The three-dimensional(3D)morphologies of Al_(2) Cu IMCs under different growth rates were quantified using volume,specific surface area,interconnectivity,tortuosity,and Gaussian curvature.The faceted morphology under slow growth rate was divided into three different types,including single hollow prism,irregular prism lacking partial faces,and coalesced prism consisting of two adjacent crystals.The morphological transition from faceted prism to non-faceted algae-like,irregular tree-like,and typically dendritic shapes with increasing growth rates was determined,reflecting the growth modes varied from lateral mode to intermediary and continuous modes.The non-faceted Al_(2) Cu dendrite had one primary stem,three groups of secondary arms,and a faceted tip.The angles between secondary arms were 120°,and the tip consisted of(011)and(011^(-))planes.This work provides a deep understanding of the formation and growth of complex IMCs in metallic alloys.
基金supported by the National Key R&D Program of China(No.2022YFB3807700)National Natural Science Foundation of China(Nos.U20A20248 and 52372247)+1 种基金Shanghai Pujiang Programme(23PJD110)Science and Technology Commission of Shanghai Municipality(No.18DZ2280800)。
文摘Lithium-and manganese-rich(LMR)oxide cathode materials are among the most attractive candidates for next-generation energy-storage materials owing to their anomalous capacity.However,severe Mn dissolution that occurs during long-term cycling,which leads to capacity loss,hinders their application prospects.In this study,nanoscale AlPO_(4)-coated Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)(LMR@APO)with significantly enhanced electrochemical performance is successfully synthesized using a simple and effective sol–gel method to mitigate Mn dissolution and suppress local structural distortion at high voltages.Because of the complex evolution of the structure and oxidation state of LMR materials during electrochemical cycling,observing and analyzing them using traditional single characterization methods may be difficult.Therefore,we combine various synchrotron-based characterization techniques to conduct a detailed analysis of the electronic and coordination structures of the cathode material from the surface to the bulk.Synchrotron-based hard and soft X-ray spectroscopies are integrated to investigate the differences in O and Mn evolution between the surfaces and bulk of the cathode.Advanced synchrotron-based transmission X-ray microscopy combined with X-ray near-edge absorption-structure technology is utilized to visualize the two-dimensional nanometer-scale reactivity of the LMR cathode.The AlPO_(4)-coating layer can stabilize the surface structure of the LMR material,effectively alleviating irreversible oxygen release on the surface and preventing the dissolution of Mn^(2+)at the interface caused by side reactions after a long cycle.Therefore,the spatial reaction uniformity of Mn is enhanced by the AlPO_(4)-coating layer,and rapid capacity decay caused by Mn deactivation is prevented.The AlPO_(4)-coating method is a facile modification strategy for high-performance LMR materials.
基金supported by the National Natural Science Foundation of China(No.52422302)Anhui Provincial Natural Science Foundation(Nos.2308085UM02,2408055UM001,and 2308085UM04)the Major Science and Technology Project“Unveiling and Commanding”of Hefei City,Anhui Province(No.2022-SZD-005).
文摘The deformation mechanism of glycerol plasticized poly(vinyl alcohol)(PVA)with different hydrolyses(88%,92%,98%)at elevated temperatures(60-100℃)was elucidated by in situ synchrotron radiation X-ray scattering.The vinyl acetate(VAc)in PVA acts as a non-crystalline chain defect,which significantly influences the plastic deformation and stretching-induced crystallization behavior of PVA.The key microstructural parameters of PVA during deformation,such as crystallinity(χ_(c)),lateral crystallite size(L),and long period(l),in combination with the stress-strain curves,were obtained.The experimental results show that the deformation process of the plasticized PVA film present a three-stage evolution:(i)a plastic deformation zone.The plastic deformation of the crystallite occurs as evidenced by the apparent decrease in crystallinity and lamellar reorientation induced by stretching;(ii)the stress softening zone.The decreasing trend of crystallinity becomes slow,and the long period becomes smaller,which indicates that PVA crystallization is induced by stretching;and(iii)the strain-hardening zone.There is a synergistic effect between the crystallite destruction and formation.Further research reveals that a high temperature and low degree of alcoholysis favor the stretching-induced crystallization of PVA,while the system with a high degree of alcoholysis shows significant characteristics of preferred crystal growth.
基金funding of this research by the German Research Foundation(Deutsche Forschungsgemeinschaft,DFG)in the framework of Research Training Group GRK 2462:Processes in natural and technical Particle-Fluid-Systems at Hamburg University of Technology(TUHH).
文摘The water drop penetration time(WDPT)test consists of placing water drops on a material's surface in order to evaluate how long it takes to penetrate the pores.It is used to evaluate the hydrophobicity of materials.This study aims at investigating in more detail the soil-water interaction during the test,exposing its mechanism.For that,a model soil named Hamburg Sand was coated with a hydrophobic fluoropolymer and then a WDPT test was performed while computed tomography(CT)images were taken.Tomography experiments were performed at the P07 high-energy materials science(HEMS)beamline,operated by Helmholtz–Zentrum Hereon,at the storage ring PETRA III at the Deutsches Elektronen-Synchrotron(DESY)in Hamburg.Using synchrotron radiation,a tomogram can be obtained in about 10 min,way less time than regular laboratory X-ray sources usually owned by universities.The faster imaging enables the observation of the drop penetration during time and thus provides insight into the dynamics of the process.After that,digital discrete image correlation is performed to track the displacement of the grains throughout time.From the results one can observe that,as the drop is absorbed at the material's surface,the grains directly around the droplet base are dragged to the liquid-air interface around the drop,revealing grain kinematics during capillary interactions of the penetrating liquid and sand grains.
基金Supported by National Natural Science Foundation of China(11175194)
文摘Magnetic alloy（MA）-loaded cavities have been widely used in compact proton and heavy-ion synchrotrons,and the MA core is the key issue in their development.Chinese-produced MA has never yet been adopted as core material for an MA-loaded cavity.To use Chinese-produced MA as the core material,it is necessary to study its properties,and compare with MA material produced elsewhere.In this paper,the properties of several MA cores made of Chinese-produced material are measured.Based on the measured results,a schematic design is produced for a cavity which could obtain 1 kV gap voltage with less than 1.5 kW power dissipation in the frequency range of0.5-7 MHz.The difference between resonant frequencies obtained from simulation and analytical results is less than10%.
