The conventional fabrication process for single-crystal nickel-based superalloy materials is directional solidifica-tion,which is classified as casting.With the rapid development of additive manufacturing(AM)technolog...The conventional fabrication process for single-crystal nickel-based superalloy materials is directional solidifica-tion,which is classified as casting.With the rapid development of additive manufacturing(AM)technologies,a novel process for fabricating single-crystal superalloys has become possible.This article reviews recent research on the AM of single-crystal nickel-based superalloys.Laser AM technologies,particularly directed energy deposition,are mainly used to repair single-crystal materials.Electron beam powder bed fusion is an innovative method for the direct fabrication of single-crystal materials.Accordingly,the mechanisms of single-crystal formation during AM are analyzed to elucidate the potential of this process route.Furthermore,this article discusses the challenges faced by AM for single-crystal fabrication,and provides perspectives on the trends of future developments.展开更多
Quantitative phase imaging(QPI)has emerged as a valuable tool for biomedical research thanks to its unique capabilities for quantifying optical thickness variation of living cells and tissues.Among many QPI methods,Fo...Quantitative phase imaging(QPI)has emerged as a valuable tool for biomedical research thanks to its unique capabilities for quantifying optical thickness variation of living cells and tissues.Among many QPI methods,Fourier ptychographic microscopy(FPM)allows long-term label-free observation and quantitative analysis of large cell populations without compromising spatial and temporal resolution.However,high spatio-temporal resolution imaging over a long-time scale(from hours to days)remains a critical challenge:optically inhomogeneous structure of biological specimens as well as mechanical perturbations and thermal fluctuations of the microscope body all result in time-varying aberration and focus drifts,significantly degrading the imaging performance for long-term study.Moreover,the aberrations are sample-and environmentdependent,and cannot be compensated by a fixed optical design,thus necessitating rapid dynamic correction in the imaging process.Here,we report an adaptive optical QPI method based on annular illumination FPM.In this method,the annular matched illumination configuration(i.e.,the illumination numerical aperture(NA)strictly equals to the objective NA),which is the key for recovering low-frequency phase information,is further utilized for the accurate imaging aberration characterization.By using only 6 low-resolution images captured with 6 different illumination angles matching the NA of a 10x,0.4 NA objective,we recover high-resolution quantitative phase images(synthetic NA of 0.8)and characterize the aberrations in real time,restoring the optimum resolution of the system adaptively.Applying our method to live-cell imaging,we achieve diffraction-limited performance(full-pitch resolution of 655 nm at a wavelength of 525 nm)across a wide field of view(1.77mm2)over an extended period of time.展开更多
Two-mm thick A1050 pure aluminum plates were successfully joined by conventional and rapid cooling friction stir welding(FSW), respectively. The microstructure and mechanical properties of the welded joints were inves...Two-mm thick A1050 pure aluminum plates were successfully joined by conventional and rapid cooling friction stir welding(FSW), respectively. The microstructure and mechanical properties of the welded joints were investigated by electron backscatter diffraction characterization, Vickers hardness measurements, and tensile testing. The results showed that liquid CO_(2) coolant significantly reduced the peak temperature and increased the cooling rate, so the rapidly cooled FSW joint exhibited fine grains with a large number of dislocations. The grain refinement mechanism of the FSW A1050 pure aluminum joint was primarily attributed to the combined effects of continuous dynamic recrystallization, grain subdivision, and geometric dynamic recrystallization. Compared with conventional FSW, the yield strength, ultimate tensile strength, and fracture elongation of rapidly cooled FSW joint were significantly enhanced, and the welding efficiency was increased from 80% to 93%. The enhanced mechanical properties and improved synergy of strength and ductility were obtained due to the increased dislocation density and remarkable grain refinement. The wear of the tool can produce several WC particles retained in the joint, and the contribution of second phase strengthening to the enhanced strength should not be ignored.展开更多
A new composite adsorbent SiO2·xH2O·yCaCl2 which is composed of macro-porous silica gel and calcium chloride is introduced. In order to analyze its adsorption theory, adsorption and desorption isotherms, BET...A new composite adsorbent SiO2·xH2O·yCaCl2 which is composed of macro-porous silica gel and calcium chloride is introduced. In order to analyze its adsorption theory, adsorption and desorption isotherms, BET surface areas, pore volumes and average pore diameters of macro-porous silica gel and four composite adsorbent samples with different CaCl2 content are measured using SEM and Asap2010 apparatus. From the adsorption isotherms, desorption isotherms and lag loops, it can be deduced that the main pore structure in macro-porous silica gel and the new composite adsorbent have two shapes: taper with one top open and taper or hyperbolic taper with both ends open. Based on the analysis of pore diameter distribution and lag loop, a sketch map showing calcium chloride filled in pore of macro-porous silica gel is presented. The adsorption isotherms at 25°C are measured. Experimental results show that the new composite adsorbent can adsorb more water than common adsorbents (macro-porous silica gel, micro-porous silica gel and synthetic zeolite 13X). In the light of the results of pore structure, adsorption isotherms and lyolysis phenomenon are analyzed.展开更多
AIzheimer＇s disease patients diagnosed with the Chinese Classification of Mental Disorders diagnostic criteria were selected from the community through on-site sampling. Levels of macro and trace elements were measur...AIzheimer＇s disease patients diagnosed with the Chinese Classification of Mental Disorders diagnostic criteria were selected from the community through on-site sampling. Levels of macro and trace elements were measured in blood samples using an atomic absorption method, and neurotransmitters were measured using a radioimmunoassay method. SPSS 13.0 was used to establish a database, and a back propagation artificial neural network for Alzheimer＇s disease prediction was simulated using Clementine 12.0 software. With scores of activities of daily living, creatinine, 5-hydroxytryptamine, age, dopamine and aluminum as input variables, the results revealed that the area under the curve in our back propagation artificial neural network was 0.929 （95% confidence interval： 0.868-0.968）, sensitivity was 90.00%, specificity was 95.00%, and accuracy was 92.50%. The findings indicated that the results of back propagation artificial neural network established based on the above six variables were satisfactory for screening and diagnosis of Alzheimer＇s disease in patients selected from the community.展开更多
A comparison study has been conducted on the strategies for synthesizing nanocrystalline Li2ZrO3 and K- doped Li2ZrO3 absorbents for CO2 capture at high temperatures, including solid-state and liquid-phase meth- ods, ...A comparison study has been conducted on the strategies for synthesizing nanocrystalline Li2ZrO3 and K- doped Li2ZrO3 absorbents for CO2 capture at high temperatures, including solid-state and liquid-phase meth- ods, citrate route, and starch-assisted sol-gel method combined with freeze-drying technique. The absorption properties, including uptake rate and absorption capacity, of synthesized absorbents were investigated by thermo- gravimetric analysis （TGA） at different CO2 partial pressures. The nanosized Li2ZrO3 crystals synthesized by the citrate route exhibit a faster uptake and a higher, nearly stoichiometric absorption capacity than those synthesized by the solid-state and liquid-phase methods. The doping of K into Li2ZrO3 can significantly improve the uptake rate of CO2, especially at low CO2 partial pressures. For the synthesis of K-doped Li2ZrO3, the citrate route has poor reproducibility and scalability, whereas the starch-assisted sol-gel method combined with freeze-drying technique is reproducible and easily scaled up, and the thus synthesized absorbents possess excellent CO2 capture properties.展开更多
This paper deals with the problem of intercepting maneuvering targets with terminal angle constraints for missiles subjected to three-dimensional non-decoupling engagement geometry.To achieve the finite-time intercept...This paper deals with the problem of intercepting maneuvering targets with terminal angle constraints for missiles subjected to three-dimensional non-decoupling engagement geometry.To achieve the finite-time interception and satisfactory overload characteristics, a time varying sliding mode control methodology is developed based on a time base generator function. The main feature of the proposed guidance law guarantees the Line-of-Sight(LOS) angles to converge to small neighborhoods of the desired values at the interception time. First, a fractional power extended state observer is used to estimate the unknown target acceleration, which can significantly reduce the adaptive switching gain. The fractional power extended state observer enjoys the advantage of better noise tolerance. Then, a newly designed sliding mode surface is constructed by introducing a time base generator function and the time-varying sliding mode guidance law is developed based on this time-varying sliding surface. The proposed guidance law significantly reduces the overload magnitudes. Numerical simulations are carried out to verify the performance of the proposed guidance law.展开更多
Transport of intensity equation(TIE)is a well-established non-interferometric phase retrieval approach that enables quantitative phase imaging(QPI)by simply measuring intensity images at multiple axially displaced pla...Transport of intensity equation(TIE)is a well-established non-interferometric phase retrieval approach that enables quantitative phase imaging(QPI)by simply measuring intensity images at multiple axially displaced planes.The advantage of a TIE-based QPI system is its compatibility with partially coherent illumination,which provides speckle-free imaging with resolution beyond the coherent diffraction limit.However,TIE is generally implemented with a brightfield(BF)configuration,and the maximum achievable imaging resolution is still limited to the incoherent diffraction limit(twice the coherent diffraction limit).It is desirable that TIE-related approaches can surpass this limit and achieve high-throughput[high-resolution and wide field of view(FOV)]QPI.We propose a hybrid BF and darkfield transport of intensity(HBDTI)approach for highthroughput quantitative phase microscopy.Two through-focus intensity stacks corresponding to BF and darkfield illuminations are acquired through a low-numerical-aperture(NA)objective lens.The high-resolution and large-FOV complex amplitude(both quantitative absorption and phase distributions)can then be synthesized based on an iterative phase retrieval algorithm taking the coherence model decomposition into account.The effectiveness of the proposed method is experimentally verified by the retrieval of the USAF resolution target and different types of biological cells.The experimental results demonstrate that the half-width imaging resolution can be improved from 1230 nm to 488 nm with 2.5×expansion across a 4×FOV of 7.19 mm2,corresponding to a 6.25×increase in space-bandwidth product from∼5 to∼30.2 megapixels.In contrast to conventional TIE-based QPI methods where only BF illumination is used,the synthetic aperture process of HBDTI further incorporates darkfield illuminations to expand the accessible object frequency,thereby significantly extending the maximum available resolution from 2NA to∼5NA with a∼5×promotion of the coherent diffraction limit.Given its capability for展开更多
The hardfacing alloys with different concentrations of titanium were deposited on carbon steel substrates by shielded metal arc welding, and the effect of titanium content on the microstructure characteristics of the ...The hardfacing alloys with different concentrations of titanium were deposited on carbon steel substrates by shielded metal arc welding, and the effect of titanium content on the microstructure characteristics of the hardfacing alloys was investigated. The wear resistance test of the hardfacing alloys was carried out by using a slurry rubber wheel abrasion test machine, and the wear behaviour was also studied. The results indicate that the addition of titanium can effectively promote the precipitation of the complex carbides of Nb and Ti due to the prior precipitation of titanium carbide which acts as nucleation sites for complex carbides. With the increase of titanium content, the wear resistance of the hardfacing alloys is increased gradually resulting from the refinement of microstructure and dispersive distribution of fine carbide precipitates. And the wear mechanism is mainly minimum plastic deformation with interrupted grooves due to the strengthening and protecting effects of carbide precipitates.展开更多
Biomass-derived carbon materials for lithiumion batteries emerge as one of the most promising anodes from sustainable perspective.However,improving the reversible capacity and cycling performance remains a long-standi...Biomass-derived carbon materials for lithiumion batteries emerge as one of the most promising anodes from sustainable perspective.However,improving the reversible capacity and cycling performance remains a long-standing challenge.By combining the benefits of K2CO_(3) activation and KMnO_(4) hydrothermal treatment,this work proposes a two-step activation method to load MnO_(2) charge transfer onto biomass-derived carbon(KAC@MnO_(2)).Comprehensive analysis reveals that KAC@MnO_(2) has a micro-mesoporous coexistence structure and uniform surface distribution of MnO_(2),thus providing an improved electrochemical performance.Specifically,KAC@MnO_(2) exhibits an initial chargedischarge capacity of 847.3/1813.2 mAh·g^(-1) at 0.2 A·g^(-1),which is significantly higher than that of direct pyrolysis carbon and K2CO_(3) activated carbon,respectively.Furthermore,the KAC@MnO_(2) maintains a reversible capacity of 652.6 mAh·g^(-1) after 100 cycles.Even at a high current density of 1.0 A·g^(-1),KAC@MnO_(2) still exhibits excellent long-term cycling stability and maintains a stable reversible capacity of 306.7 mAh·g^(-1) after 500 cycles.Compared with reported biochar anode materials,the KAC@MnO_(2) prepared in this work shows superior reversible capacity and cycling performance.Additionally,the Li+insertion and de-insertion mechanisms are verified by ex situ X-ray diffraction analysis during the chargedischarge process,helping us better understand the energy storage mechanism of KAC@MnO_(2).展开更多
Kenics static mixers(KSM)are extensively used in industrial mixing-reaction processes by virtue of high mixing efficiency,low power homogenization and easy continuous production.Resolving liquid droplet size and its d...Kenics static mixers(KSM)are extensively used in industrial mixing-reaction processes by virtue of high mixing efficiency,low power homogenization and easy continuous production.Resolving liquid droplet size and its distribution and thus revealing the dispersion characteristics are of great significance for structural optimization and process intensification in the KSM.In this work,a computational fluid dynamics-population balance model(CFD-PBM)coupled method is employed to systematically investigate the effects of operating conditions and structural parameters of KSM on droplet size and its distribution,to further reveal the liquid-liquid dispersion characteristics.Results indicate that higher Reynolds numbers or higher dispersed phase volume fractions increase energy dissipation,reducing Sauter mean diameter(SMD)of dispersed phase droplets and with a shift in droplet size distribution(DSD)towards smaller size.Smaller aspect ratios,greater blade twist and assembly angles amplify shear rate,leading to smaller droplet size and a narrower DSD in the smaller range.The degree of impact exerted by the aspect ratio is notably greater.Notably,mixing elements with different spin enhance shear and stretching efficiency.Compared to the same spin,SMD becomes 3.7-5.8 times smaller in the smaller size range with a significantly narrower distribution.Taking into account the pressure drop and efficiency in a comprehensive manner,optimized structural parameters for the mixing element encompass an aspect ratio of 1-1.5,a blade twist angle of 180°,an assembly angle of 90°,and interlaced assembly of adjacent elements with different spin.This work provides vital theoretical underpinning and future reference for enhancing KSM performance.展开更多
Surface passivation via post-treatment is an important strategy for improving power conversion efficiency and operational stability of perovskite solar cells.However,so far the interaction mechanisms between passivati...Surface passivation via post-treatment is an important strategy for improving power conversion efficiency and operational stability of perovskite solar cells.However,so far the interaction mechanisms between passivating additive and perovskite are not well understood.Here,we report the atomic-scale interaction of surface passivating additive 2,2-difluoroethylammonium bromine(2FEABr)on the MAPbI_(3).It is found that the bulky 2FEA+cations tend to distribute at film surface,while the Br−anions diffuse from surface into bulk.A combination of 19F,207Pb,and 2H solid-state NMR further reveal the Br−anions’partial substitution for the I−sites,the restricted motion of partial MA+cations,and the firmed perovskite lattices,which would improve charge transport and stability of the perovskite films.Optical spectroscopy and ultraviolet photoelectron spectroscopy demonstrate that the 2FEABr induced surface passivation and energetic modification suppress the nonradiative recombination loss.These findings enable the efficiency of the p-i-n structured PSC significantly increasing from 19.44 to 21.06%,accompanied by excellent stability.Our work further establishes more knowledge link between passivating additive and PSC performance.展开更多
In this work,we introduce a kind of new structured radial grating,which is named the even-type sinusoidal amplitude radial(ETASR)grating.Based on diffraction theory and the principle of stationary phase,a comprehensiv...In this work,we introduce a kind of new structured radial grating,which is named the even-type sinusoidal amplitude radial(ETASR)grating.Based on diffraction theory and the principle of stationary phase,a comprehensive theoretical investigation on the diffraction patterns of ETASR gratings is conducted.Theoretical results show that novel carpet beams with beautiful optical structures and distinctive characteristics have been constructed on the basics of the ETASR grating.Their diffraction patterns are independent of propagation distance,that is,the new carpet beams have diffraction-free propagating characteristics.The non-diffracting carpet beams are divided into two types by beam characteristics:non-diffracting integer-order and half-integer-order carpet beams.Subsequently,we experimentally generate these carpet beams using the ETASR grating.Finally,their particularly interesting optical morphology and features are explored through numerical simulations and experiments.展开更多
Single-cell RNA sequencing(scRNA-seq)has emerged as a valuable tool for studying cellular heterogeneity in various fields,particularly in virological research.By studying the viral and cellular transcriptomes,the dyna...Single-cell RNA sequencing(scRNA-seq)has emerged as a valuable tool for studying cellular heterogeneity in various fields,particularly in virological research.By studying the viral and cellular transcriptomes,the dynamics of viral infection can be investigated at a single-cell resolution.However,limited studies have been conducted to investigate whether RNA transcripts from clinical samples contain substantial amounts of viral RNAs,and a specific computational framework for efficiently detecting viral reads based on scRNA-seq data has not been developed.Hence,we introduce DVsc,an open-source framework for precise quantitative analysis of viral infection from single-cell transcriptomics data.When applied to approximately 200 diverse clinical samples that were infected by more than 10 different viruses,DVsc demonstrated high accuracy in systematically detecting viral infection across a wide array of cell types.This innovative bioinformatics pipeline could be crucial for addressing the potential effects of surreptitiously invading viruses on certain illnesses,as well as for designing novel medicines to target viruses in specific host cell subsets and evaluating the efficacy of treatment.DVsc supports the FASTQ format as an input and is compatible with multiple single-cell sequencing platforms.Moreover,it could also be applied to sequences from bulk RNA sequencing data.DVsc is available at http://62.234.32.33:5000/DVsc.展开更多
Nickel diselenide(NiSe_(2)),which has a high theoretical capacity,has attracted considerable attention as a promis-ing anode material for sodium-ion batteries(SIBs).Nevertheless,the intrinsically low conductivity,larg...Nickel diselenide(NiSe_(2)),which has a high theoretical capacity,has attracted considerable attention as a promis-ing anode material for sodium-ion batteries(SIBs).Nevertheless,the intrinsically low conductivity,large volume variation,and significant aggregation of NiSe_(2)during sodiation/desodiation remain significant obstacles to its application.Herein,we report flower-like Fe-doped NiSe_(2)/C hybrid spheres(denoted as Fe-NiSe_(2)/C)fabricated by a glucose intercalation strategy for efficient sodium storage.These Fe-NiSe_(2)/C hybrid spheres are composed of thin porous carbon nanosheets decorated with Fe-NiSe_(2)nanoparticles.In situ introduced carbon nanosheets derived from intercalated glucose accompanied by moderate Fe doping in NiSe2 nanoparticles can provide ac-celerated ion/electron transfer kinetics through fast ion channels in the flower-like architecture and intimately contacted interfaces between NiSe_(2)and carbon nanosheets as well as maintain structural integrity by alleviating volume variation.Consequently,the optimal anode of the Fe-NiSe_(2)/C hybrid spheres delivered a high discharge capacity of 415 mAh g^(-1)at 0.5 A g^(-1),outstanding rate capability(243 mAh g^(-1)at 5 A g^(-1)),and significantly enhanced cycling stability(388 mAh g^(-1)at 1 A g^(-1)over 200 cycles).This work offers an efficient and valu-able strategy for realizing tailored heteroatom doping in transition metal selenides,accompanied by an in situ combination of conductive carbonaceous networks for advanced alkali metal ion batteries.展开更多
Currently,the conversion of waste plastics into high-value products via catalytic pyrolysis enables the advancement of plastics’open-loop recycling.However,enhancing selectivity remains a critical challenge.This stud...Currently,the conversion of waste plastics into high-value products via catalytic pyrolysis enables the advancement of plastics’open-loop recycling.However,enhancing selectivity remains a critical challenge.This study introduces a novel approach to catalytic pyrolysis,utilizing a combination of MCM-41 and modified gallium-based HZSM-5 catalysts,to achieve exceptional selectivity for aromatic liquid-phase products from linear low-density polyethylene.Firstly,to enhance the probability of dehydroaromatization optimization,the type and proportion of metal active sites within the HZSM-5 catalyst are fine-tuned,which would establish equilibrium with acid sites,resulting in a remarkable 15.72%increase in the selectivity of aromatic hydrocarbons.Secondly,to enhance the accessibility of volatiles to active sites,mesoporous MCM-41 with cracking capabilities is introduced.The doping ratio of MCM-41 is meticulously controlled to facilitate the diffusion of cracked volatiles to the active centers of modified gallium-based HZSM-5,enabling efficient reforming reactions.Experimental findings demonstrate that MCM-41 significantly enhances the dehydroaromatization activity of the modified gallium-based HZSM-5 catalyst.Under the influence of MCM-41:Zr_(2)Ga_(3)/HZSM-5=1:2 catalyst,the selectivity for aromatic hydrocarbons reaches an impressive 93.11%,with a notable 60.01%selectivity for benzene,toluene,ethylbenzene,and xylene.Lastly,this study proposes a plausible pathway for the generation of high-value aromatic hydrocarbons using the combined catalyst.展开更多
The high-temperature tensile behavior of laser welded Ti-22Al-25Nb (at%) joints was investigated at 500,650,800,and 1 000 ℃.The temperatures for tensile tests were selected according to the phase transformation seque...The high-temperature tensile behavior of laser welded Ti-22Al-25Nb (at%) joints was investigated at 500,650,800,and 1 000 ℃.The temperatures for tensile tests were selected according to the phase transformation sequence of Ti2AlNb-based alloys.At temperatures lower than the B2+O phase field (500 ℃) and higher than the B2+O phase field (1 000 ℃),the joints fracture in the base metal in ductile fracture mode.By contrast,the joints exhibit obvious high-temperature brittleness in the B2+O phase field (650 °C and 800 ℃).Heat treatments were conducted with respect to the thermal history of tensile specimens.Intergranular microcracks along the grain boundary of B2 phase are found in the fusion zone after the heat treatments at 650 ℃ and 800 ℃.The high-temperature brittleness at 650 ℃ and 800 ℃ is attributed to the B2→O transformation along the grain boundary.The stress concentration caused by the volume change of B2→O transformation also contributes to the high-temperature brittleness of laser welded Ti-22Al-25Nb joints.展开更多
Quantitative phase imaging(QPI)by differential phase contrast(DPC)with partially coherent illumination provides speckle-free imaging and lateral resolution beyond the coherent diffraction limit,demonstrating great pot...Quantitative phase imaging(QPI)by differential phase contrast(DPC)with partially coherent illumination provides speckle-free imaging and lateral resolution beyond the coherent diffraction limit,demonstrating great potential in biomedical imaging applications.Generally,DPC employs weak object approximation to linearize the phase-to-intensity image formation,simplifying the solution to the phase retrieval as a two-dimensional deconvolution with the corresponding phase transfer function.Despite its widespread adoption,weak object approximation still lacks a precise and clear definition,suggesting that the accuracy of the QPI results,especially for samples with large phase values,is yet to be verified.In this paper,we analyze the weak object approximation condition quantitatively and explicitly give its strict definition that is applicable to arbitrary samples and illumination apertures.Furthermore,an iterative deconvolution QPI technique based on pseudo-weak object approximation is proposed to overcome the difficulty of applying DPC to large-phase samples without additional data acquisition.Experiments with standard microlens arrays and MCF-7 cells demonstrated that the proposed method can effectively extend DPC beyond weak object approximation to high-precision three-dimensional morphological characterization of large-phase technical and biological samples.展开更多
A new kind of AlCoCrFeNiTi high-entropy alloy(HEA)as a grain refiner was prepared by vacuum arc melting.In this work,the effects of HEA(1.0 wt.%,2.0 wt.%and 3.0 wt.%)on the microstructure and mechanical properties of ...A new kind of AlCoCrFeNiTi high-entropy alloy(HEA)as a grain refiner was prepared by vacuum arc melting.In this work,the effects of HEA(1.0 wt.%,2.0 wt.%and 3.0 wt.%)on the microstructure and mechanical properties of pure aluminum were studied.The microstructure was characterized and examined by scanning electron microscope(SEM),energy dispersive X-ray spectroscopy(EDS),X-ray diffraction(XRD),electron probe micro-analyzer(EPMA)and transmission electron microscopy(TEM)to indicate the refining abilities and mechanism of HEA on pure aluminum.Results show that the addition of HEA refined both the macrostructure and microstructure of pure aluminum.When 1.0 wt.%HEA was added,most coarse columnar grains were refined into equiaxed crystals,and as the amount of HEA increased to 2.0 wt.%and3.0 wt.%,aluminum grains were further refined,and the grain boundaries were nearly indistinguishable.Moreover,the morphology ofα-Al transformed from coarse columnar crystals to equiaxed grains,and the mean size ofα-Al grains decreased from 374μm to 27μm.The Al3Ti,Al3Ni,and nano-phase precipitated from the aluminum alloy with HEA in the solidification.The typical rod-like nano-phases distributed interdendritic regions ofα-Al.The average length of nano-phases is 2568 nm,4372 nm,and 6907 nm and the average diameter is 112 nm,103 nm,and 92 nm when 1.0 wt.%,2.0 wt.%and 3.0 wt.%HEA were added to the pure aluminum,respectively.The ultimate tensile strength(UTS)and yield strength(YS)were improved in all samples,whereas the elongation(El)was decreased with increasing HEA concentration.When 3.0 wt.%HEA was added into the aluminum melt,the UTS was improved by 145.2%from62 MPa to 152 MPa,the YS was increased by 173.8%from 42 MPa to 115 MPa,and the El was decreased by 33.3%from 39%to 26%.展开更多
Tongxinluo has been widely used in China for the treatment of acute stroke and for neuroprotection. However, there are few positron emission tomography （PET） studies on the neuroprotective effect of Tongxinluo on ce...Tongxinluo has been widely used in China for the treatment of acute stroke and for neuroprotection. However, there are few positron emission tomography （PET） studies on the neuroprotective effect of Tongxinluo on cerebral ischemia/reperfusion in small animals. In the present study, Tongxinluo superfine powder suspension or its vehicle was administered intragastrically to rats for 5 successive days before middle cerebral artery occlusion, ^18Ffluorodeoxyglucose （FDG） small animal PET imaging showed that at 1 and 2 weeks after cerebral ischemia/reperfusion, glucose metabolism in the ischemic area was greater in rats that had received Tongxinluo than in those that had received the vehicle. Nissl staining showed that 2 weeks after cerebral ischemia/reperfusion, there was less neuronal loss in the prefrontal cortex in Tongxinluo-treated rats than in controls. In addition, Tongxinluo-treated animals showed better neurologic function and lower cerebral infarct volume than rats that received the vehicle. These findings suggest that Tongxinluo exhibits neuroprotective effects in cerebral ischemia/reperfusion injury and demonstrates that ^18F-FDG small animal PET imaging is a useful tool with which to study the molecular pharmacology of traditional Chinese medicine.展开更多
基金supported by National Key R&D Program of China(Grant No.2017YFB1103300).
文摘The conventional fabrication process for single-crystal nickel-based superalloy materials is directional solidifica-tion,which is classified as casting.With the rapid development of additive manufacturing(AM)technologies,a novel process for fabricating single-crystal superalloys has become possible.This article reviews recent research on the AM of single-crystal nickel-based superalloys.Laser AM technologies,particularly directed energy deposition,are mainly used to repair single-crystal materials.Electron beam powder bed fusion is an innovative method for the direct fabrication of single-crystal materials.Accordingly,the mechanisms of single-crystal formation during AM are analyzed to elucidate the potential of this process route.Furthermore,this article discusses the challenges faced by AM for single-crystal fabrication,and provides perspectives on the trends of future developments.
基金supported by the National Natural Science Foundation of China(61905115,62105151,62175109,U21B2033,62105156)Leading Technology of Jiangsu Basic Research Plan(BK20192003),Youth Foundation of Jiangsu Province(BK20190445,BK20210338)+1 种基金Fundamental Research Funds for the Central Universities(30920032101)Open Research Fund of Jiangsu Key Laboratory of Spectral Imaging&Intelligent Sense(JSGP202105,JSGP202201).
文摘Quantitative phase imaging(QPI)has emerged as a valuable tool for biomedical research thanks to its unique capabilities for quantifying optical thickness variation of living cells and tissues.Among many QPI methods,Fourier ptychographic microscopy(FPM)allows long-term label-free observation and quantitative analysis of large cell populations without compromising spatial and temporal resolution.However,high spatio-temporal resolution imaging over a long-time scale(from hours to days)remains a critical challenge:optically inhomogeneous structure of biological specimens as well as mechanical perturbations and thermal fluctuations of the microscope body all result in time-varying aberration and focus drifts,significantly degrading the imaging performance for long-term study.Moreover,the aberrations are sample-and environmentdependent,and cannot be compensated by a fixed optical design,thus necessitating rapid dynamic correction in the imaging process.Here,we report an adaptive optical QPI method based on annular illumination FPM.In this method,the annular matched illumination configuration(i.e.,the illumination numerical aperture(NA)strictly equals to the objective NA),which is the key for recovering low-frequency phase information,is further utilized for the accurate imaging aberration characterization.By using only 6 low-resolution images captured with 6 different illumination angles matching the NA of a 10x,0.4 NA objective,we recover high-resolution quantitative phase images(synthetic NA of 0.8)and characterize the aberrations in real time,restoring the optimum resolution of the system adaptively.Applying our method to live-cell imaging,we achieve diffraction-limited performance(full-pitch resolution of 655 nm at a wavelength of 525 nm)across a wide field of view(1.77mm2)over an extended period of time.
基金Funded by the Natural Science Foundation of Jiangsu Province(No.BK20211067)“Qing Lan” Project of Jiangsu Province。
文摘Two-mm thick A1050 pure aluminum plates were successfully joined by conventional and rapid cooling friction stir welding(FSW), respectively. The microstructure and mechanical properties of the welded joints were investigated by electron backscatter diffraction characterization, Vickers hardness measurements, and tensile testing. The results showed that liquid CO_(2) coolant significantly reduced the peak temperature and increased the cooling rate, so the rapidly cooled FSW joint exhibited fine grains with a large number of dislocations. The grain refinement mechanism of the FSW A1050 pure aluminum joint was primarily attributed to the combined effects of continuous dynamic recrystallization, grain subdivision, and geometric dynamic recrystallization. Compared with conventional FSW, the yield strength, ultimate tensile strength, and fracture elongation of rapidly cooled FSW joint were significantly enhanced, and the welding efficiency was increased from 80% to 93%. The enhanced mechanical properties and improved synergy of strength and ductility were obtained due to the increased dislocation density and remarkable grain refinement. The wear of the tool can produce several WC particles retained in the joint, and the contribution of second phase strengthening to the enhanced strength should not be ignored.
文摘A new composite adsorbent SiO2·xH2O·yCaCl2 which is composed of macro-porous silica gel and calcium chloride is introduced. In order to analyze its adsorption theory, adsorption and desorption isotherms, BET surface areas, pore volumes and average pore diameters of macro-porous silica gel and four composite adsorbent samples with different CaCl2 content are measured using SEM and Asap2010 apparatus. From the adsorption isotherms, desorption isotherms and lag loops, it can be deduced that the main pore structure in macro-porous silica gel and the new composite adsorbent have two shapes: taper with one top open and taper or hyperbolic taper with both ends open. Based on the analysis of pore diameter distribution and lag loop, a sketch map showing calcium chloride filled in pore of macro-porous silica gel is presented. The adsorption isotherms at 25°C are measured. Experimental results show that the new composite adsorbent can adsorb more water than common adsorbents (macro-porous silica gel, micro-porous silica gel and synthetic zeolite 13X). In the light of the results of pore structure, adsorption isotherms and lyolysis phenomenon are analyzed.
基金supported by the National Natural Science Foundation of China,No.30760214
文摘AIzheimer＇s disease patients diagnosed with the Chinese Classification of Mental Disorders diagnostic criteria were selected from the community through on-site sampling. Levels of macro and trace elements were measured in blood samples using an atomic absorption method, and neurotransmitters were measured using a radioimmunoassay method. SPSS 13.0 was used to establish a database, and a back propagation artificial neural network for Alzheimer＇s disease prediction was simulated using Clementine 12.0 software. With scores of activities of daily living, creatinine, 5-hydroxytryptamine, age, dopamine and aluminum as input variables, the results revealed that the area under the curve in our back propagation artificial neural network was 0.929 （95% confidence interval： 0.868-0.968）, sensitivity was 90.00%, specificity was 95.00%, and accuracy was 92.50%. The findings indicated that the results of back propagation artificial neural network established based on the above six variables were satisfactory for screening and diagnosis of Alzheimer＇s disease in patients selected from the community.
基金The financial supports from the National Basic Research Program of China （2009CB626607）, the National Natural Science Foundation of China （21036006）, the Program for Changjiang Scholars and Innovative Research Team in Chinese Universities （IRT0980）, and the Program for Zhejiang Leading Team of Science and Technology Innovation （2011 R09020-05） are gratefully acknowledged.
文摘A comparison study has been conducted on the strategies for synthesizing nanocrystalline Li2ZrO3 and K- doped Li2ZrO3 absorbents for CO2 capture at high temperatures, including solid-state and liquid-phase meth- ods, citrate route, and starch-assisted sol-gel method combined with freeze-drying technique. The absorption properties, including uptake rate and absorption capacity, of synthesized absorbents were investigated by thermo- gravimetric analysis （TGA） at different CO2 partial pressures. The nanosized Li2ZrO3 crystals synthesized by the citrate route exhibit a faster uptake and a higher, nearly stoichiometric absorption capacity than those synthesized by the solid-state and liquid-phase methods. The doping of K into Li2ZrO3 can significantly improve the uptake rate of CO2, especially at low CO2 partial pressures. For the synthesis of K-doped Li2ZrO3, the citrate route has poor reproducibility and scalability, whereas the starch-assisted sol-gel method combined with freeze-drying technique is reproducible and easily scaled up, and the thus synthesized absorbents possess excellent CO2 capture properties.
基金co-supported by the National Natural Science Foundation of China(Nos.61673034 and 62073019)。
文摘This paper deals with the problem of intercepting maneuvering targets with terminal angle constraints for missiles subjected to three-dimensional non-decoupling engagement geometry.To achieve the finite-time interception and satisfactory overload characteristics, a time varying sliding mode control methodology is developed based on a time base generator function. The main feature of the proposed guidance law guarantees the Line-of-Sight(LOS) angles to converge to small neighborhoods of the desired values at the interception time. First, a fractional power extended state observer is used to estimate the unknown target acceleration, which can significantly reduce the adaptive switching gain. The fractional power extended state observer enjoys the advantage of better noise tolerance. Then, a newly designed sliding mode surface is constructed by introducing a time base generator function and the time-varying sliding mode guidance law is developed based on this time-varying sliding surface. The proposed guidance law significantly reduces the overload magnitudes. Numerical simulations are carried out to verify the performance of the proposed guidance law.
基金the National Natural Science Foundation of China(61905115,62105151,62175109,and U21B2033)Leading Technology of Jiangsu Basic Research Plan(BK20192003)+2 种基金Youth Foundation of Jiangsu Province(BK20190445,BK20210338)Fundamental Research Funds for the Central Universities(30920032101)Open Research Fund of Jiangsu Key Laboratory of Spectral Imaging and Intelligent Sense(JSGP202105).
文摘Transport of intensity equation(TIE)is a well-established non-interferometric phase retrieval approach that enables quantitative phase imaging(QPI)by simply measuring intensity images at multiple axially displaced planes.The advantage of a TIE-based QPI system is its compatibility with partially coherent illumination,which provides speckle-free imaging with resolution beyond the coherent diffraction limit.However,TIE is generally implemented with a brightfield(BF)configuration,and the maximum achievable imaging resolution is still limited to the incoherent diffraction limit(twice the coherent diffraction limit).It is desirable that TIE-related approaches can surpass this limit and achieve high-throughput[high-resolution and wide field of view(FOV)]QPI.We propose a hybrid BF and darkfield transport of intensity(HBDTI)approach for highthroughput quantitative phase microscopy.Two through-focus intensity stacks corresponding to BF and darkfield illuminations are acquired through a low-numerical-aperture(NA)objective lens.The high-resolution and large-FOV complex amplitude(both quantitative absorption and phase distributions)can then be synthesized based on an iterative phase retrieval algorithm taking the coherence model decomposition into account.The effectiveness of the proposed method is experimentally verified by the retrieval of the USAF resolution target and different types of biological cells.The experimental results demonstrate that the half-width imaging resolution can be improved from 1230 nm to 488 nm with 2.5×expansion across a 4×FOV of 7.19 mm2,corresponding to a 6.25×increase in space-bandwidth product from∼5 to∼30.2 megapixels.In contrast to conventional TIE-based QPI methods where only BF illumination is used,the synthetic aperture process of HBDTI further incorporates darkfield illuminations to expand the accessible object frequency,thereby significantly extending the maximum available resolution from 2NA to∼5NA with a∼5×promotion of the coherent diffraction limit.Given its capability for
基金Funded by the National Natural Science Foundation of China(No.51101050)Fundamental Research Funds for the Central Universities,Natural Science Foundation of Jiangsu Province of China(No.BK20141156)Program for Outstanding Innovative Talents in Hohai University
文摘The hardfacing alloys with different concentrations of titanium were deposited on carbon steel substrates by shielded metal arc welding, and the effect of titanium content on the microstructure characteristics of the hardfacing alloys was investigated. The wear resistance test of the hardfacing alloys was carried out by using a slurry rubber wheel abrasion test machine, and the wear behaviour was also studied. The results indicate that the addition of titanium can effectively promote the precipitation of the complex carbides of Nb and Ti due to the prior precipitation of titanium carbide which acts as nucleation sites for complex carbides. With the increase of titanium content, the wear resistance of the hardfacing alloys is increased gradually resulting from the refinement of microstructure and dispersive distribution of fine carbide precipitates. And the wear mechanism is mainly minimum plastic deformation with interrupted grooves due to the strengthening and protecting effects of carbide precipitates.
基金supported by the National Natural Science Foundation of China(Grant No.22078278)Hunan Innovative Talent Project(Grant No.2022RC1111)+1 种基金the Key project of Hunan Provincial Education Department(Grant No.22A0131)the State Key Laboratory of Clean Energy Utilization(Open Fund Project No.ZJUCEU2021009).
文摘Biomass-derived carbon materials for lithiumion batteries emerge as one of the most promising anodes from sustainable perspective.However,improving the reversible capacity and cycling performance remains a long-standing challenge.By combining the benefits of K2CO_(3) activation and KMnO_(4) hydrothermal treatment,this work proposes a two-step activation method to load MnO_(2) charge transfer onto biomass-derived carbon(KAC@MnO_(2)).Comprehensive analysis reveals that KAC@MnO_(2) has a micro-mesoporous coexistence structure and uniform surface distribution of MnO_(2),thus providing an improved electrochemical performance.Specifically,KAC@MnO_(2) exhibits an initial chargedischarge capacity of 847.3/1813.2 mAh·g^(-1) at 0.2 A·g^(-1),which is significantly higher than that of direct pyrolysis carbon and K2CO_(3) activated carbon,respectively.Furthermore,the KAC@MnO_(2) maintains a reversible capacity of 652.6 mAh·g^(-1) after 100 cycles.Even at a high current density of 1.0 A·g^(-1),KAC@MnO_(2) still exhibits excellent long-term cycling stability and maintains a stable reversible capacity of 306.7 mAh·g^(-1) after 500 cycles.Compared with reported biochar anode materials,the KAC@MnO_(2) prepared in this work shows superior reversible capacity and cycling performance.Additionally,the Li+insertion and de-insertion mechanisms are verified by ex situ X-ray diffraction analysis during the chargedischarge process,helping us better understand the energy storage mechanism of KAC@MnO_(2).
基金supported by the National Natural Science Foundation of China(22078278)Hunan Innovative Talent Project(2022RC1111)+2 种基金Hunan Provincial Education Bureau Foundation(22A0131)Hunan Province Higher Education Key Laboratory of Green Catalysis and Industrial Reaction Process IntensificationFurong Plan Provincial Enterprise Technology Innovation and Entrepreneurship Team.
文摘Kenics static mixers(KSM)are extensively used in industrial mixing-reaction processes by virtue of high mixing efficiency,low power homogenization and easy continuous production.Resolving liquid droplet size and its distribution and thus revealing the dispersion characteristics are of great significance for structural optimization and process intensification in the KSM.In this work,a computational fluid dynamics-population balance model(CFD-PBM)coupled method is employed to systematically investigate the effects of operating conditions and structural parameters of KSM on droplet size and its distribution,to further reveal the liquid-liquid dispersion characteristics.Results indicate that higher Reynolds numbers or higher dispersed phase volume fractions increase energy dissipation,reducing Sauter mean diameter(SMD)of dispersed phase droplets and with a shift in droplet size distribution(DSD)towards smaller size.Smaller aspect ratios,greater blade twist and assembly angles amplify shear rate,leading to smaller droplet size and a narrower DSD in the smaller range.The degree of impact exerted by the aspect ratio is notably greater.Notably,mixing elements with different spin enhance shear and stretching efficiency.Compared to the same spin,SMD becomes 3.7-5.8 times smaller in the smaller size range with a significantly narrower distribution.Taking into account the pressure drop and efficiency in a comprehensive manner,optimized structural parameters for the mixing element encompass an aspect ratio of 1-1.5,a blade twist angle of 180°,an assembly angle of 90°,and interlaced assembly of adjacent elements with different spin.This work provides vital theoretical underpinning and future reference for enhancing KSM performance.
基金supported by the National Science Foundation of China grant(21875067)the Fundamental Research Funds for the Central Universities,Shanghai Rising-Star(19QA1403100)+4 种基金East China Normal University(ECNU)Multifunctional Platform for InnovationThe Ministry of Science and Technology of the People’s Republic of China(No.2018YFF01012504)the National Key Research and Development Program of China(2017YFA0206600)the National Natural Science Foundation of China(51773045,21772030,51922032,21961160720)for financial support。
文摘Surface passivation via post-treatment is an important strategy for improving power conversion efficiency and operational stability of perovskite solar cells.However,so far the interaction mechanisms between passivating additive and perovskite are not well understood.Here,we report the atomic-scale interaction of surface passivating additive 2,2-difluoroethylammonium bromine(2FEABr)on the MAPbI_(3).It is found that the bulky 2FEA+cations tend to distribute at film surface,while the Br−anions diffuse from surface into bulk.A combination of 19F,207Pb,and 2H solid-state NMR further reveal the Br−anions’partial substitution for the I−sites,the restricted motion of partial MA+cations,and the firmed perovskite lattices,which would improve charge transport and stability of the perovskite films.Optical spectroscopy and ultraviolet photoelectron spectroscopy demonstrate that the 2FEABr induced surface passivation and energetic modification suppress the nonradiative recombination loss.These findings enable the efficiency of the p-i-n structured PSC significantly increasing from 19.44 to 21.06%,accompanied by excellent stability.Our work further establishes more knowledge link between passivating additive and PSC performance.
基金supported by the National Natural Science Foundation of China(Nos.11974314 and 11674288).
文摘In this work,we introduce a kind of new structured radial grating,which is named the even-type sinusoidal amplitude radial(ETASR)grating.Based on diffraction theory and the principle of stationary phase,a comprehensive theoretical investigation on the diffraction patterns of ETASR gratings is conducted.Theoretical results show that novel carpet beams with beautiful optical structures and distinctive characteristics have been constructed on the basics of the ETASR grating.Their diffraction patterns are independent of propagation distance,that is,the new carpet beams have diffraction-free propagating characteristics.The non-diffracting carpet beams are divided into two types by beam characteristics:non-diffracting integer-order and half-integer-order carpet beams.Subsequently,we experimentally generate these carpet beams using the ETASR grating.Finally,their particularly interesting optical morphology and features are explored through numerical simulations and experiments.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.31830054 and 32293204)the Beijing Municipal Health Commission,China(JingYiYan2019-8Grant No.XTCX20180503).
文摘Single-cell RNA sequencing(scRNA-seq)has emerged as a valuable tool for studying cellular heterogeneity in various fields,particularly in virological research.By studying the viral and cellular transcriptomes,the dynamics of viral infection can be investigated at a single-cell resolution.However,limited studies have been conducted to investigate whether RNA transcripts from clinical samples contain substantial amounts of viral RNAs,and a specific computational framework for efficiently detecting viral reads based on scRNA-seq data has not been developed.Hence,we introduce DVsc,an open-source framework for precise quantitative analysis of viral infection from single-cell transcriptomics data.When applied to approximately 200 diverse clinical samples that were infected by more than 10 different viruses,DVsc demonstrated high accuracy in systematically detecting viral infection across a wide array of cell types.This innovative bioinformatics pipeline could be crucial for addressing the potential effects of surreptitiously invading viruses on certain illnesses,as well as for designing novel medicines to target viruses in specific host cell subsets and evaluating the efficacy of treatment.DVsc supports the FASTQ format as an input and is compatible with multiple single-cell sequencing platforms.Moreover,it could also be applied to sequences from bulk RNA sequencing data.DVsc is available at http://62.234.32.33:5000/DVsc.
基金the financial support provided by the Zhejiang Provincial Natural Science Foundation of China(Grant No.LY21E020010)National Natural Science Foundation of China(Grant No.52102315)+1 种基金Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(2021SZ-TD006)Science and Technology Program of Zhejiang University Institute of Wenzhou(Grant No.XMGLKJZX-202206).
文摘Nickel diselenide(NiSe_(2)),which has a high theoretical capacity,has attracted considerable attention as a promis-ing anode material for sodium-ion batteries(SIBs).Nevertheless,the intrinsically low conductivity,large volume variation,and significant aggregation of NiSe_(2)during sodiation/desodiation remain significant obstacles to its application.Herein,we report flower-like Fe-doped NiSe_(2)/C hybrid spheres(denoted as Fe-NiSe_(2)/C)fabricated by a glucose intercalation strategy for efficient sodium storage.These Fe-NiSe_(2)/C hybrid spheres are composed of thin porous carbon nanosheets decorated with Fe-NiSe_(2)nanoparticles.In situ introduced carbon nanosheets derived from intercalated glucose accompanied by moderate Fe doping in NiSe2 nanoparticles can provide ac-celerated ion/electron transfer kinetics through fast ion channels in the flower-like architecture and intimately contacted interfaces between NiSe_(2)and carbon nanosheets as well as maintain structural integrity by alleviating volume variation.Consequently,the optimal anode of the Fe-NiSe_(2)/C hybrid spheres delivered a high discharge capacity of 415 mAh g^(-1)at 0.5 A g^(-1),outstanding rate capability(243 mAh g^(-1)at 5 A g^(-1)),and significantly enhanced cycling stability(388 mAh g^(-1)at 1 A g^(-1)over 200 cycles).This work offers an efficient and valu-able strategy for realizing tailored heteroatom doping in transition metal selenides,accompanied by an in situ combination of conductive carbonaceous networks for advanced alkali metal ion batteries.
基金National Natural Science Foundation of China(Grant No.22078278)Hunan Innovative Talent Project(Grant No.2022RC1111)Key Project of Hunan Provincial Education Department(Grant No.22A0131).
文摘Currently,the conversion of waste plastics into high-value products via catalytic pyrolysis enables the advancement of plastics’open-loop recycling.However,enhancing selectivity remains a critical challenge.This study introduces a novel approach to catalytic pyrolysis,utilizing a combination of MCM-41 and modified gallium-based HZSM-5 catalysts,to achieve exceptional selectivity for aromatic liquid-phase products from linear low-density polyethylene.Firstly,to enhance the probability of dehydroaromatization optimization,the type and proportion of metal active sites within the HZSM-5 catalyst are fine-tuned,which would establish equilibrium with acid sites,resulting in a remarkable 15.72%increase in the selectivity of aromatic hydrocarbons.Secondly,to enhance the accessibility of volatiles to active sites,mesoporous MCM-41 with cracking capabilities is introduced.The doping ratio of MCM-41 is meticulously controlled to facilitate the diffusion of cracked volatiles to the active centers of modified gallium-based HZSM-5,enabling efficient reforming reactions.Experimental findings demonstrate that MCM-41 significantly enhances the dehydroaromatization activity of the modified gallium-based HZSM-5 catalyst.Under the influence of MCM-41:Zr_(2)Ga_(3)/HZSM-5=1:2 catalyst,the selectivity for aromatic hydrocarbons reaches an impressive 93.11%,with a notable 60.01%selectivity for benzene,toluene,ethylbenzene,and xylene.Lastly,this study proposes a plausible pathway for the generation of high-value aromatic hydrocarbons using the combined catalyst.
基金Funded by the National Natural Science Foundation of China(Nos.51804097 and 51879089)the Fundamental Research Funds for the Central Universities of China(No.B200202219)+2 种基金the Changzhou Sci&Tech Program(No.CJ20190049)the State Key Lab of Advanced Welding and JoiningHarbin Institute of Technology(No.AWJ-19M16)。
文摘The high-temperature tensile behavior of laser welded Ti-22Al-25Nb (at%) joints was investigated at 500,650,800,and 1 000 ℃.The temperatures for tensile tests were selected according to the phase transformation sequence of Ti2AlNb-based alloys.At temperatures lower than the B2+O phase field (500 ℃) and higher than the B2+O phase field (1 000 ℃),the joints fracture in the base metal in ductile fracture mode.By contrast,the joints exhibit obvious high-temperature brittleness in the B2+O phase field (650 °C and 800 ℃).Heat treatments were conducted with respect to the thermal history of tensile specimens.Intergranular microcracks along the grain boundary of B2 phase are found in the fusion zone after the heat treatments at 650 ℃ and 800 ℃.The high-temperature brittleness at 650 ℃ and 800 ℃ is attributed to the B2→O transformation along the grain boundary.The stress concentration caused by the volume change of B2→O transformation also contributes to the high-temperature brittleness of laser welded Ti-22Al-25Nb joints.
基金Key National Industrial Technology Cooperation Foundation of Jiangsu Province(BZ2022039)Biomedical Competition Foundation of Jiangsu Province(BE2022847)+5 种基金National Major Scientific Instrument Development Project(62227818)Open Research Fund of Jiangsu Key Laboratory of Spectral Imaging and Intelligent Sense(JSGP202105,JSGP202201)Fundamental Research Funds for the Central Universities(30920032101)Youth Foundation of Jiangsu Province(BK20190445,BK20210338)Leading Technology of Jiangsu Basic Research Plan(BK20192003)National Natural Science Foundation of China(61905115,62105151,62175109,U21B2033)。
文摘Quantitative phase imaging(QPI)by differential phase contrast(DPC)with partially coherent illumination provides speckle-free imaging and lateral resolution beyond the coherent diffraction limit,demonstrating great potential in biomedical imaging applications.Generally,DPC employs weak object approximation to linearize the phase-to-intensity image formation,simplifying the solution to the phase retrieval as a two-dimensional deconvolution with the corresponding phase transfer function.Despite its widespread adoption,weak object approximation still lacks a precise and clear definition,suggesting that the accuracy of the QPI results,especially for samples with large phase values,is yet to be verified.In this paper,we analyze the weak object approximation condition quantitatively and explicitly give its strict definition that is applicable to arbitrary samples and illumination apertures.Furthermore,an iterative deconvolution QPI technique based on pseudo-weak object approximation is proposed to overcome the difficulty of applying DPC to large-phase samples without additional data acquisition.Experiments with standard microlens arrays and MCF-7 cells demonstrated that the proposed method can effectively extend DPC beyond weak object approximation to high-precision three-dimensional morphological characterization of large-phase technical and biological samples.
基金financially supported by the National Natural Science Foundation of China(No.51561021)the State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology(No.SKLAB02019007)the National Innovation Training Program of College Students of China(No.DC2019165 DC2019161)。
文摘A new kind of AlCoCrFeNiTi high-entropy alloy(HEA)as a grain refiner was prepared by vacuum arc melting.In this work,the effects of HEA(1.0 wt.%,2.0 wt.%and 3.0 wt.%)on the microstructure and mechanical properties of pure aluminum were studied.The microstructure was characterized and examined by scanning electron microscope(SEM),energy dispersive X-ray spectroscopy(EDS),X-ray diffraction(XRD),electron probe micro-analyzer(EPMA)and transmission electron microscopy(TEM)to indicate the refining abilities and mechanism of HEA on pure aluminum.Results show that the addition of HEA refined both the macrostructure and microstructure of pure aluminum.When 1.0 wt.%HEA was added,most coarse columnar grains were refined into equiaxed crystals,and as the amount of HEA increased to 2.0 wt.%and3.0 wt.%,aluminum grains were further refined,and the grain boundaries were nearly indistinguishable.Moreover,the morphology ofα-Al transformed from coarse columnar crystals to equiaxed grains,and the mean size ofα-Al grains decreased from 374μm to 27μm.The Al3Ti,Al3Ni,and nano-phase precipitated from the aluminum alloy with HEA in the solidification.The typical rod-like nano-phases distributed interdendritic regions ofα-Al.The average length of nano-phases is 2568 nm,4372 nm,and 6907 nm and the average diameter is 112 nm,103 nm,and 92 nm when 1.0 wt.%,2.0 wt.%and 3.0 wt.%HEA were added to the pure aluminum,respectively.The ultimate tensile strength(UTS)and yield strength(YS)were improved in all samples,whereas the elongation(El)was decreased with increasing HEA concentration.When 3.0 wt.%HEA was added into the aluminum melt,the UTS was improved by 145.2%from62 MPa to 152 MPa,the YS was increased by 173.8%from 42 MPa to 115 MPa,and the El was decreased by 33.3%from 39%to 26%.
基金supported by the National Natural Science Foundation of China,No.81173435,81303115the Natural Science Foundation of Guangdong Province,No.S2013040016915the Postdoctoral Foundation of China,No.BBK42913K09,201003345
文摘Tongxinluo has been widely used in China for the treatment of acute stroke and for neuroprotection. However, there are few positron emission tomography （PET） studies on the neuroprotective effect of Tongxinluo on cerebral ischemia/reperfusion in small animals. In the present study, Tongxinluo superfine powder suspension or its vehicle was administered intragastrically to rats for 5 successive days before middle cerebral artery occlusion, ^18Ffluorodeoxyglucose （FDG） small animal PET imaging showed that at 1 and 2 weeks after cerebral ischemia/reperfusion, glucose metabolism in the ischemic area was greater in rats that had received Tongxinluo than in those that had received the vehicle. Nissl staining showed that 2 weeks after cerebral ischemia/reperfusion, there was less neuronal loss in the prefrontal cortex in Tongxinluo-treated rats than in controls. In addition, Tongxinluo-treated animals showed better neurologic function and lower cerebral infarct volume than rats that received the vehicle. These findings suggest that Tongxinluo exhibits neuroprotective effects in cerebral ischemia/reperfusion injury and demonstrates that ^18F-FDG small animal PET imaging is a useful tool with which to study the molecular pharmacology of traditional Chinese medicine.
