After stroke,even high-functioning individuals may experience compromised bimanual coordination and fine motor dexterity,leading to reduced functional independence.Bilateral arm training has been proposed as a promisi...After stroke,even high-functioning individuals may experience compromised bimanual coordination and fine motor dexterity,leading to reduced functional independence.Bilateral arm training has been proposed as a promising intervention to address these deficits.However,the neural basis of the impairment of functional fine motor skills and their relationship to bimanual coordination performance in stroke patients remains unclear,limiting the development of more targeted interventions.To address this gap,our study employed functional near-infrared spectroscopy to investigate cortical responses in patients after stroke as they perform functional tasks that engage fine motor control and coordination.Twenty-four high-functioning patients with ischemic stroke(7 women,17 men;mean age 64.75±10.84 years)participated in this cross-sectional observational study and completed four subtasks from the Purdue Pegboard Test,which measures unimanual and bimanual finger and hand dexterity.We found significant bilateral activation of the sensorimotor cortices during all Purdue Pegboard Test subtasks,with bimanual tasks inducing higher cortical activation than the assembly subtask.Importantly,patients with better bimanual coordination exhibited lower cortical activation during the other three Purdue Pegboard Test subtasks.Notably,the observed neural response patterns varied depending on the specific subtask.In the unaffected hand task,the differences were primarily observed in the ipsilesional hemisphere.In contrast,the bilateral sensorimotor cortices and the contralesional hemisphere played a more prominent role in the bimanual task and assembly task,respectively.While significant correlations were found between cortical activation and unimanual tasks,no significant correlations were observed with bimanual tasks.This study provides insights into the neural basis of bimanual coordination and fine motor skills in high-functioning patients after stroke,highlighting task-dependent neural responses.The findings also suggest that patients who exhibit better bimanual performance demonstrate more efficient cortical activation.Therefore,incorporating bilateral arm training in post-stroke rehabilitation is important for better outcomes.The combination of functional near-infrared spectroscopy with functional motor paradigms is valuable for assessing skills and developing targeted interventions in stroke rehabilitation.展开更多
A novel fiber Bragg grating(FBG)sensor with three-dimensional(3D)fused deposition modeling(FDM)approach is proposed for effective stress measurement in soil mass.The three-diaphragm structure design is developed to me...A novel fiber Bragg grating(FBG)sensor with three-dimensional(3D)fused deposition modeling(FDM)approach is proposed for effective stress measurement in soil mass.The three-diaphragm structure design is developed to measure earth and water pressures simultaneously.The proposed transducer has advantages of small size,high sensitivity,low cost,immunity to electromagnetic interference and rapid prototyping.The working principle,design parameters,and manufacturing details are discussed.The proposed transducer was calibrated for earth and water pressures measurement by using weights and a specially designed pressure chamber,respectively.The calibration results showed that the wavelength of the transducer was proportional to the applied pressure.The sensitivity coefficients of the earth and water pressures were 12.633 nm/MPa and 6.282 nm/MPa,respectively.Repeated tests and error analysis demonstrated the excellent stability and accuracy of the earth and water pressure measurements.The performance of the proposed transducer was further verified by a model experimental test and numerical analysis,which indicated that the proposed transducer has great potential for practical applications.展开更多
Due to the complexity of decision-making problems and the subjectivity of decision-makers in practical application,it is necessary to adopt different forms of information expression according to the actual situation o...Due to the complexity of decision-making problems and the subjectivity of decision-makers in practical application,it is necessary to adopt different forms of information expression according to the actual situation of specific decision-making problems and choose the best method to solve them.Multi-valued neutrosophic set,as an extension of neutrosophic set,can more effectively and accurately describe incomplete,uncertain or inconsistent information.TODIM and TOPSIS methods are two commonly used multi-attribute decision-making methods,each of which has its advantages and disadvantages.This paper proposes a new method based on TODIM and TOPSIS to solve multi-attribute decision-making problems under multi-valued neutrosophic environment.After introducing the related theory of multi-valued neutrosophic set and the traditional TODIM and TOPSIS methods,the new method based on a combination of TODIM and TOPSIS methods is described.And then,two illustrative examples proved the feasibility and validity of the proposed method.Finally,the result has been compared with some existing methods under the same examples and the proposed method’s superiority has been proved.This paper studies this kind of decision-making problem from algorithm idea,algorithm steps and decision-making influencing factors.展开更多
An analytical methodology based on an O-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroquinidine(MQD)-silica hybrid monolithic column was developed for the enantioseparation of 9-fluorenylmethoxycarbonyl(FMOC)deriv...An analytical methodology based on an O-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroquinidine(MQD)-silica hybrid monolithic column was developed for the enantioseparation of 9-fluorenylmethoxycarbonyl(FMOC)derivatized amino acids by nano-liquid chromatography.The mobile phase was optimized including the apparent pH,content of ACN,and concentration of the buffer to obtain a satisfactory enantioresolution performance.27 FMOC derivatized amino acids including 19 protein and 8 non-protein amino acids were tested,and 19 out of them were enantiomerically discriminated obtaining baseline separation for 11 of them.Analytical characteristics of the method were evaluated for norvaline and tryptophan in terms of linearity,precision,accuracy,limits of detection(LOD)and quantitation(LOQ)showing good performance to be applied to the enantiomeric determination of these amino acids in dietary supplements.LOD and LOQ values were 9.3 and 31 mM for norvaline enantiomers and 7.5 and 25 mM for tryptophan enantiomers,respectively.The contents of D-norvaline and D-tryptophan were below their respective LODs in all the analyzed samples.Quantitation of L-tryptophan and L-norvaline showed good agreement with the labeled contents except for one sample which did not show presence of L-norvaline,contrary to the label indication.展开更多
In this paper,three kinds of shear walls with full sleeve grouting,fully defective sleeve and partially defective are designed for finite element analysis to analyze the influence of defects on the seismic performance...In this paper,three kinds of shear walls with full sleeve grouting,fully defective sleeve and partially defective are designed for finite element analysis to analyze the influence of defects on the seismic performance of shear walls.The research shows that at the beginning of loading(5 s),the three models begin to appear compressive damage at the bottom of the wall in all three models.The damage of the defect-free model develops rapidly,and the damage of the fully defective model is basically the same as that of the partially defective model.With the gradual increase of displacement control(15 s),the compressive damages at the foot of the wall in the defect-free and partially defective grouting model are obvious,with plastic hinge formed in the foot of the wall,and the phenomenon of development along the pier body showing up.When the structure is damaged,the overall compressive damages of the wall in the defect-free and partially defective models are obvious,and the damage on the defective side of the partially defective model is slightly deficient.While the maximum stress of pre-stressed reinforcement in the defect-freemodel is concentrated at the top of the sleeve,themaximumstress of the pre-stressed steel bar in the fully defective model appears at the end of the steel bar in the sleeve.The hysteresis curve shape of the non-defectmodel and partially defective model are basically the same,showing a“shuttle”shape with a sound energy dissipation effect.The hysteresis curve shape of the fully defective model appears an obvious“pinch”phenomenon.The yield displacement levels of the defect-free and partially defective models are smaller than that of the fully defective model structure.The stiffness degradation curves of the three models basically overlap with one another.Before the limit displacement,the stiffness results of the non-defect model and the partially defective model are greater than that of the fully defective model.When the displacement is loaded to 20 mm,the stiffness degradation of the three models is equivalent.展开更多
Aims: Cardiovascular disease (CVD) and periodontitis are both chronic inflammatory disorders which are highly prevalent in populations. Bacteria involved in the periodontal disease have been found to be cardiovascular...Aims: Cardiovascular disease (CVD) and periodontitis are both chronic inflammatory disorders which are highly prevalent in populations. Bacteria involved in the periodontal disease have been found to be cardiovascular risk markers. Periodontal pathogens may contribute to the atheroma pathogenesis. Severe periodontitis is correlated with the prevalence of bacteraemia, and poor periodontal status is an important risk factor for CVD. However, the association is unclear. If the association is causal, the periodontal therapy will lead to an attenuation of the effects on CVD. The study aimed to study if the periodontal intervention therapy presented therapeutic effects on CVD. Methods: English language literature on periodontal intervention therapy on CVD is causal or not. The literature revealed 62 papers associated with this study to investigate the relationship between periodontitis and CVD. Results: The literature supported the idea that periodontal infections had been associated with CVD. Certain periodontal therapy is associated with bacteraemia, and the prevalence of bacteraemia may arise from periodontal therapy and poor oral hygiene practices. Periodontal therapy not only presented therapeutic effects by reducing cytokine activity and C-response protein (CRP), but also caused bacteraemia transitorily. Effective antibiotic prophylaxis pre- or post-periodontal therapy presented some beneficial effects on bacteraemia or CVD. Conclusion: Severe periodontitis causes systemic inflammation and endothelial dysfunction, and goes beyond the oral cavity. Periodontal intervention would contribute to the prevention of atherosclerosis, and antibiotic prophylaxis would be helpful to decrease bacteraemia and reduce the onset of CVD.展开更多
Oxygen is crucial in influencing the microstructure evolution of selective laser melted(SLMed)Ti–6Al–4V,significantly impacting its applicability in various sectors.Therefore,this study investigates the influnce of ...Oxygen is crucial in influencing the microstructure evolution of selective laser melted(SLMed)Ti–6Al–4V,significantly impacting its applicability in various sectors.Therefore,this study investigates the influnce of oxygen on microstructure evolution,particularlyα′martensite transformation and refinement mechanisms.Four alloys,Ti–6Al–4V–xO(x=0.11,0.16,0.21,and 0.25 wt%),were fabricated by the SLM process.The martensite start temperature(M_(s))of Ti–6Al–4V,as evaluated by computation,is 656.8°C,and oxygen was found to increase the M_(s) by about 10°C per 0.1 wt%.The SLMed alloy samples exhibit[001]_(β)growth texture along the build direction.Crystallographic analysis of martensite morphology suggests internal twinning on{1011}planes as the lattice invariant strain,which becomes more predominant with increasing oxygen content.Refinement of α′martensite plates by oxygen is due to increased lattice distortion,reduced prior β grain size,and oxygen segregation toβgrain boundaries.Our findings contribute to improving the understanding of the effect of oxygen on the transformation mechanism ofα′martensite during SLM of Ti–6Al–4V.展开更多
Promoting synaptic plasticity and inducing functional reorganization of residual nerve fibers hold clinical significance for restoring motor function following spinal cord injury.Neuromagnetic stimulation targeting th...Promoting synaptic plasticity and inducing functional reorganization of residual nerve fibers hold clinical significance for restoring motor function following spinal cord injury.Neuromagnetic stimulation targeting the nerve roots has been shown to improve motor function by enhancing nerve conduction in the injured spinal cord and restoring the synaptic ultrastructure of both the sensory and motor cortex.However,our understanding of the neurophysiological mechanisms by which nerve root magnetic stimulation facilitates motor function recovery in the spinal cord is limited,and its role in neuroplasticity remains unclear.In this study,we established a model of spinal cord injury in adult male Sprague–Dawley rats by applying moderate compression at the T10 vertebra.We then performed magnetic stimulation on the L5 nerve root for 3 weeks,beginning on day 3 post-injury.At day 22 post-injury,we observed that nerve root magnetic stimulation downregulated the level of interleukin-6 in the injured spinal cord tissue of rats.Additionally,this treatment reduced neuronal damage and glial scar formation,and increased the number of neurons in the injured spinal cord.Furthermore,nerve root magnetic stimulation decreased the levels of acetylcholine,norepinephrine,and dopamine,and increased the expression of synaptic plasticity-related m RNA and proteins PSD95,GAP43,and Synapsin II.Taken together,these results showed that nerve root magnetic stimulation alleviated neuronal damage in the injured spinal cord,regulated synaptic plasticity,and suppressed inflammatory responses.These findings provide laboratory evidence for the clinical application of nerve root magnetic stimulation in the treatment of spinal cord injury.展开更多
The microstructure evolutions and nucleation mechanisms of GH4169G alloy were studied by optical microscope, electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). The hot compression test...The microstructure evolutions and nucleation mechanisms of GH4169G alloy were studied by optical microscope, electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). The hot compression tests were performed different imposed reductions in the range of true strain from 0.12 to 1.2 at the temperatures of 930 °-1050 ° with strain rates of 0.01 s^-1-l s^-1. It is found that cumulative and local misorientation increase firstly and then decrease when the strain is increased due to the progress of dynamic recrystallization (DRX). The low angle boundaries (LAGBs) rapidly develop to high angle boundaries (HAGBs) at relatively high deformation temperature or the low strain rate. There are three DRX mechanisms observed for GH4169 G alloy during hot deformation. Discontinuous dynamic recrystallization (DDRX) as the dominant mechanism for GH4169 G alloy is characterized by typical necklace structures and bulged-original boundaries. Besides, different deformation bands with dislocation cells formed in deformed matrix at low temperature and large strain, which indicates that continuous dynamic recrystallization (CDRX) contributed to the DRX process. The twin boundaries lost their coherent characteristics and provide sites for nucleation, which also accelerates the nucleation of DRX.展开更多
By binding molecular probes that target tumor cells, gold nanoparticles (AuNPs) with superior characteristics have shown great potential in tumor molecular imaging studies. The non-invasive, high-resolution, and thr...By binding molecular probes that target tumor cells, gold nanoparticles (AuNPs) with superior characteristics have shown great potential in tumor molecular imaging studies. The non-invasive, high-resolution, and three-dimensional imaging of the targeted AuNPs within the tumor is desirable for both diagnosis and therapy. In this study, gold nanoflowers (AuNFs) are presented as a novel contrast agent for photoacoustic tomography (PAT). By binding to folic acid, the molecular probe, the tail-vein injected AuNFs concentrated within the tumor site in mice; this was clearly visualized by three-dimensional (3D) PAT imaging. In addition, toxicity assay proved that AuNFs were harmless to living cells and animals. Our results demonstrate that AuNFs have great potential in tumor molecular imaging.展开更多
Flow behavior and processing map play important roles in the hot deformation process of titanium alloys. In this research, compression Gleeble tests have been carried out to investigate the stress-strain relationship ...Flow behavior and processing map play important roles in the hot deformation process of titanium alloys. In this research, compression Gleeble tests have been carried out to investigate the stress-strain relationship at temperatures ranging from 700 to 1000 ℃ and strain rates ranging from 0.001 to 1 s-1 for ATI 425 titanium alloy. Arrhenius type constitutive equation was obtained to describe the compressive flow behavior with modification of additional deformation dead zone, friction model, temperature model and strain rate. The introduction of novel calculation method for α value in Arrhenius equation gives more accurate fitting than traditional one. Processing maps were drawn based on the distribution of dissipator co-content, and optimized deformation temperature and strain rate range obtained. It is proven to be accurate and effective through the experimental results. The microstructure analysis shows that more dynamic recrystallization can be achieved in the area with larger ηvalue on the processing map.展开更多
The development of highly efficient and earth-abundant oxygen evolution/ reduction reaction (OER/ORR) catalysts is essential for rechargeable metal-air batteries. Herein, cobalt-based hydroxide nanoparticles @ N-dop...The development of highly efficient and earth-abundant oxygen evolution/ reduction reaction (OER/ORR) catalysts is essential for rechargeable metal-air batteries. Herein, cobalt-based hydroxide nanoparticles @ N-doping carbonic framework (CoOHCat@NCF) core-shell structures have been designed as highly stable and efficient OER/ORR bifunctional catalysts. The obtained composite shows enhanced catalytic activities and excellent stability in alkaline media. In the OER, a high turnover frequency (2.03 s^-1 at an overpotential of 0.36 V), low overpotential at high current density (100 mA.cm-2 requiring an overpotential of 0.38 V), and excellent stability (100 mA·cm^-2 for one week with no activity loss) have been achieved. Furthermore, although cobalt species-based catalysts are known as good ORR catalysts, their hybridization with NCF obtained from metal organic frameworks successfully enhanced their ORR activities. The efficient activity of CoOHCat@NCF as a bifunctional oxygen electrocatalyst can be ascribed to the core-shell structures stabilizing the active catalytic sites and the porous shell structure favoring electrocatalysis-related mass transport.展开更多
This paper reports a high-performance H2S gas sensing material that is made of ZnO nanowires(NWs)modified by an optimal amount of ZnS to form nano-hete rojunctions.Compared with the intrinsic ZnONWs,the three differen...This paper reports a high-performance H2S gas sensing material that is made of ZnO nanowires(NWs)modified by an optimal amount of ZnS to form nano-hete rojunctions.Compared with the intrinsic ZnONWs,the three differently modified nano-heterostructure material ZnO-ZnS-x(x=5,10,15)shows significant improvement in sensing performance to H2S at the working temperatures of 100-400℃,especially in the low temperature range(<300℃).The chemiresistive sensor with ZnO-ZnS-10 sensingmaterial exhibits the largest response signal to H2S among all the other ZnO-ZnS-x(x=5,10,15,20)sensors.Its response signal to 5 ppm H2S at 150℃is about 2.7 times to that of the ZnO-NWs sensor.Besides,the ZnO-ZnS-10 sensor also features satisfactory selectivity and repeatability at 150℃.With the technical advantage attributed to the reduction of the redesigned band gap at the interface between ZnO and ZnS,the ZnO-ZnS hete ro structure sensor rather than the traditional ZnO-NWs sensor can be used for high-sensitivity application at low working temperature.展开更多
The effects of heating rate on the alloy element partitioning and mechanical properties during the phase transformation ofα→βin Ti-6Al-4 V alloy under solution treatment have been investigated by the experiments an...The effects of heating rate on the alloy element partitioning and mechanical properties during the phase transformation ofα→βin Ti-6Al-4 V alloy under solution treatment have been investigated by the experiments and phase field simulations,which reveal the evolutions of microstructure and compositions at the non-equilibrium state and well verify the experimental results.The specific results indicate that the compositions measured through electron probe micro-analysis(EPMA)under a lower heating rate are close to the equilibrium ones corresponding to the solution temperature.Heating up to the target solution temperature,as the heating rate increases,the Al content decreases and V increases in the primaryα(α_(p))grain with a larger size,the volume fraction ofα_(p)increases and the composition gradient betweenα_(p)andβphases gets steeper.The interrelated relationship among the diffusion,compositions,solution temperature and free energy of the system has been discussed in detail.Moreover,increasing the heating rate(~20.0 K/min)may help to improve the mechanical properties of the alloy by mainly adjusting theα_(p)/β;volume fractions,α_(p)particle size and secondaryα(α_(p))size during the process of heating up to the solution temperature.These results may shed some light on the optimization of the knowledge-based heat treatment route.展开更多
The nucleation and propagation of h011]superdislocations in intermetallic TiAl were investigated using molecular dynamics simulations and static energetics calculation,as part of our systematic effort to understand th...The nucleation and propagation of h011]superdislocations in intermetallic TiAl were investigated using molecular dynamics simulations and static energetics calculation,as part of our systematic effort to understand the twining and dislocation behavior of alloys based on c-TiAl.It was found that compared to ordinary dislocations in disordered crystals,superdislocations in ordered TiAl lattice behave differently when sheared in the two opposite senses along[0"11]direction.This difference is due to the lower L10lattice symmetry compared with the face-centered cubic(fcc)lattice that it based on,with different yield stress and strain,and dislocation core dissociation and motion.Superdislocations nucleated in the form of loops dissociated in a planar manner into four Shockley partials separated by three kinds of faults:superlattice intrinsic stacking fault(SISF),anti-phase domain boundary(APB)and complex stacking fault(CSF),with partial separations depending on the sense of shearing and dislocation character.During loop expansion,the dislocation core changes both in width and dissociation manner depending on the character of the segment in the loop.The core contains four partials close to edge orientation,gradually changing to three fold near 60°,and finally into twofold dissociationaround 30°character.Superdislocations may have multiple critical resolved shear stresses(CRSS)for motion depending on dissociation and shearing sense even for the same slip system,with lower critical stress for the motion when SISF is in leading position.展开更多
Exploration of heavy metals and organic pollutants, their leaching capacity along with health and environmental risks in contaminated industrial construction and demolition waste (ICDW) within a pesticide manufactu...Exploration of heavy metals and organic pollutants, their leaching capacity along with health and environmental risks in contaminated industrial construction and demolition waste (ICDW) within a pesticide manufacturing plant were investigated. A maximum content of 90.8 mg·kg-1 Cd was found present in the wastes, which might originate from phosphorus rocks and industrial sulfuric acid used in pesticide production processes. An average concentration of 979.8 mg·kg-1 dichlorovos and other 11 organophosphorus pesticide were also detected. Relatively high leaching rates of around 4.14‰ were obtained from laboratory simulated ICDW using both glacial acetic acidsodium hydroxide and deionized water. Pesticide pollutants had the strongest tendency to retaining on dry bricks (leaching rate 1.68 9‰) compared to mortar-coatings, etc. due to their different physical characteristics and octanol-water partioning coefficient. Mobility of pesticide from on-site ICDW by water was spatially correlated to waste types, process sections and human activities, with a flux of leaching rate between 5.9‰ to 27.4%. Risk-based corrective action (RBCA) model was used to simulate the risk of contaminated ICDW debris randomly scattered. Oral and demlal ingestion amount by local workers was 9.8 × 10-3 and 1.9 × 10-2 mg.(kg-d)-1, respectively. Potential leaching risk to aquatic systems exceeded the limit for nearly 75% waste. Environmental and health risk exceedance was found in most ICDW, while the risk value of the most severely contaminated brick waste was 660 times beyond critical level. Implications for waste management involving construction and deconstruction work, waste transferring and regulation supplying were also provided.展开更多
Alzheimer’s disease(AD)is a prominent form of dementia,characterized by aggregation of the amyloidβ-peptide(Aβ)plaques and neurofibrillary tangles,loss of synapses and neurons,and degeneration of cognitive function...Alzheimer’s disease(AD)is a prominent form of dementia,characterized by aggregation of the amyloidβ-peptide(Aβ)plaques and neurofibrillary tangles,loss of synapses and neurons,and degeneration of cognitive functions.Currently,although a variety of medications can relieve some of the symptoms,there is no cure for AD.Recent breakthroughs in the stem cell field provide promising strategies for AD treatment.Stem cells including embryonic stem cells(ESCs),neural stem cells(NSCs),mesenchymal stem cells(MSCs),and induced pluripotent stem cells(iPSCs)are potentials for AD treatment.However,the limitation of cell sources,safety issues,and ethical issues restrict their applications in AD.Recently,the direct reprogramming of induced neural progenitor cells(iNPCs)has shed light on the treatment of AD.In this review,we will discuss the latest progress,challenges,and potential applications of direct reprogramming in AD treatment.展开更多
Variant selection under specific applied stresses during precipitation of a plates from prior-βmatrix in Ti-6 Al-4 V was investigated by 3 D phase field simulations.The model incorporates the Burgers transformation p...Variant selection under specific applied stresses during precipitation of a plates from prior-βmatrix in Ti-6 Al-4 V was investigated by 3 D phase field simulations.The model incorporates the Burgers transformation path fromβto a phase,with consideration of interfacial energy anisotropy,externally applied stresses and elastic interactions among a variants andβmatrix.The Gibbs free energy and atomic mobility data are taken from available thermodynamic and kinetic databases.It was found that external stresses have a profound influence on variant selection,and the selection has a sensitive dependence,as evidenced by both interaction energy calculations and phase field simulations.Compared with normal stresses,shear stresses applied in certain directions were found more effective in accelerating the transformation,with a stronger preference to fewer variants.The volume fractions of various a variants and the final microstructure were determined by both the external stress and the elastic interaction among different variants.The a clusters formed by variants with Type2 misorientation([11-20]/60°)relation were found more favored than those with Type4([-1055-3]/63.26°)under certain applied tensile stress such as along<111>β.The mechanical properties of different microstructures from our phase field simulation under different conditions were calculated for different loading conditions,utilizing crystal plastic finite element simulation.The mechanical behavior of the various microstructures from phase field simulation can be evaluated well before the alloys are fabricated,and therefore it is possible to select microstructure for optimizing the mechanical properties of the alloy through thermomechanical processing based on the two types of simulations.展开更多
Large size polysynthetically twinned crystals of Ti-46 Al-8 Nb alloy with a parallel lamellar microstructure were successfully prepared using a Ti-43 Al-3 Si seed by our new operation.A large amount of columnar B2 pha...Large size polysynthetically twinned crystals of Ti-46 Al-8 Nb alloy with a parallel lamellar microstructure were successfully prepared using a Ti-43 Al-3 Si seed by our new operation.A large amount of columnar B2 phase paralleling to the growth direction was found in the final lamellar microstructure.Higher growth rate(>30 mm/h)led to the failure of seeding process.Based on these results,a new mechanism is proposed to describe the seeding process of the hypo-peritectic Ti Al alloys.The peritecticαphase is suggested to directly nucleate from the melt,and then act as nucleus for transformedαphase in the subsequentβtoαtransformation.At the higher growth rate,the appearance ofβphase secondary dendrites and homogeneous nucleation lead to the failure of seeding process.High Nb addition leads to a large amount of residualβphase,and theseβdendrites finally evolve into B2 phase.The room temperature tensile elongation was measured to be 11.9-18.5%for Ti-46 Al-8 Nb PST crystals,which is the highest ever reported value for Ti Al based alloys.展开更多
基金supported by the National Key R&D Program of China,No.2020YFC2004202(to DX).
文摘After stroke,even high-functioning individuals may experience compromised bimanual coordination and fine motor dexterity,leading to reduced functional independence.Bilateral arm training has been proposed as a promising intervention to address these deficits.However,the neural basis of the impairment of functional fine motor skills and their relationship to bimanual coordination performance in stroke patients remains unclear,limiting the development of more targeted interventions.To address this gap,our study employed functional near-infrared spectroscopy to investigate cortical responses in patients after stroke as they perform functional tasks that engage fine motor control and coordination.Twenty-four high-functioning patients with ischemic stroke(7 women,17 men;mean age 64.75±10.84 years)participated in this cross-sectional observational study and completed four subtasks from the Purdue Pegboard Test,which measures unimanual and bimanual finger and hand dexterity.We found significant bilateral activation of the sensorimotor cortices during all Purdue Pegboard Test subtasks,with bimanual tasks inducing higher cortical activation than the assembly subtask.Importantly,patients with better bimanual coordination exhibited lower cortical activation during the other three Purdue Pegboard Test subtasks.Notably,the observed neural response patterns varied depending on the specific subtask.In the unaffected hand task,the differences were primarily observed in the ipsilesional hemisphere.In contrast,the bilateral sensorimotor cortices and the contralesional hemisphere played a more prominent role in the bimanual task and assembly task,respectively.While significant correlations were found between cortical activation and unimanual tasks,no significant correlations were observed with bimanual tasks.This study provides insights into the neural basis of bimanual coordination and fine motor skills in high-functioning patients after stroke,highlighting task-dependent neural responses.The findings also suggest that patients who exhibit better bimanual performance demonstrate more efficient cortical activation.Therefore,incorporating bilateral arm training in post-stroke rehabilitation is important for better outcomes.The combination of functional near-infrared spectroscopy with functional motor paradigms is valuable for assessing skills and developing targeted interventions in stroke rehabilitation.
基金funding support from the National Natural Science Foundation of China(Grant Nos.41972271 and 42177127)Sanya Science and Education Innovation Park of Wuhan University of Technology(Grant No.2020KF0007)。
文摘A novel fiber Bragg grating(FBG)sensor with three-dimensional(3D)fused deposition modeling(FDM)approach is proposed for effective stress measurement in soil mass.The three-diaphragm structure design is developed to measure earth and water pressures simultaneously.The proposed transducer has advantages of small size,high sensitivity,low cost,immunity to electromagnetic interference and rapid prototyping.The working principle,design parameters,and manufacturing details are discussed.The proposed transducer was calibrated for earth and water pressures measurement by using weights and a specially designed pressure chamber,respectively.The calibration results showed that the wavelength of the transducer was proportional to the applied pressure.The sensitivity coefficients of the earth and water pressures were 12.633 nm/MPa and 6.282 nm/MPa,respectively.Repeated tests and error analysis demonstrated the excellent stability and accuracy of the earth and water pressure measurements.The performance of the proposed transducer was further verified by a model experimental test and numerical analysis,which indicated that the proposed transducer has great potential for practical applications.
基金This research was funded by the Humanities and Social Sciences Foundation of Ministry of Education of the Peoples Republic of China(17YJA630115)The recipient of the founding is DX.
文摘Due to the complexity of decision-making problems and the subjectivity of decision-makers in practical application,it is necessary to adopt different forms of information expression according to the actual situation of specific decision-making problems and choose the best method to solve them.Multi-valued neutrosophic set,as an extension of neutrosophic set,can more effectively and accurately describe incomplete,uncertain or inconsistent information.TODIM and TOPSIS methods are two commonly used multi-attribute decision-making methods,each of which has its advantages and disadvantages.This paper proposes a new method based on TODIM and TOPSIS to solve multi-attribute decision-making problems under multi-valued neutrosophic environment.After introducing the related theory of multi-valued neutrosophic set and the traditional TODIM and TOPSIS methods,the new method based on a combination of TODIM and TOPSIS methods is described.And then,two illustrative examples proved the feasibility and validity of the proposed method.Finally,the result has been compared with some existing methods under the same examples and the proposed method’s superiority has been proved.This paper studies this kind of decision-making problem from algorithm idea,algorithm steps and decision-making influencing factors.
文摘An analytical methodology based on an O-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroquinidine(MQD)-silica hybrid monolithic column was developed for the enantioseparation of 9-fluorenylmethoxycarbonyl(FMOC)derivatized amino acids by nano-liquid chromatography.The mobile phase was optimized including the apparent pH,content of ACN,and concentration of the buffer to obtain a satisfactory enantioresolution performance.27 FMOC derivatized amino acids including 19 protein and 8 non-protein amino acids were tested,and 19 out of them were enantiomerically discriminated obtaining baseline separation for 11 of them.Analytical characteristics of the method were evaluated for norvaline and tryptophan in terms of linearity,precision,accuracy,limits of detection(LOD)and quantitation(LOQ)showing good performance to be applied to the enantiomeric determination of these amino acids in dietary supplements.LOD and LOQ values were 9.3 and 31 mM for norvaline enantiomers and 7.5 and 25 mM for tryptophan enantiomers,respectively.The contents of D-norvaline and D-tryptophan were below their respective LODs in all the analyzed samples.Quantitation of L-tryptophan and L-norvaline showed good agreement with the labeled contents except for one sample which did not show presence of L-norvaline,contrary to the label indication.
基金The authors are grateful for the financial support received from the National Natural Science Foundation of China(No.52078038)Basic Scientific Research Business of Central University(No.FRF-MP-20-20).
文摘In this paper,three kinds of shear walls with full sleeve grouting,fully defective sleeve and partially defective are designed for finite element analysis to analyze the influence of defects on the seismic performance of shear walls.The research shows that at the beginning of loading(5 s),the three models begin to appear compressive damage at the bottom of the wall in all three models.The damage of the defect-free model develops rapidly,and the damage of the fully defective model is basically the same as that of the partially defective model.With the gradual increase of displacement control(15 s),the compressive damages at the foot of the wall in the defect-free and partially defective grouting model are obvious,with plastic hinge formed in the foot of the wall,and the phenomenon of development along the pier body showing up.When the structure is damaged,the overall compressive damages of the wall in the defect-free and partially defective models are obvious,and the damage on the defective side of the partially defective model is slightly deficient.While the maximum stress of pre-stressed reinforcement in the defect-freemodel is concentrated at the top of the sleeve,themaximumstress of the pre-stressed steel bar in the fully defective model appears at the end of the steel bar in the sleeve.The hysteresis curve shape of the non-defectmodel and partially defective model are basically the same,showing a“shuttle”shape with a sound energy dissipation effect.The hysteresis curve shape of the fully defective model appears an obvious“pinch”phenomenon.The yield displacement levels of the defect-free and partially defective models are smaller than that of the fully defective model structure.The stiffness degradation curves of the three models basically overlap with one another.Before the limit displacement,the stiffness results of the non-defect model and the partially defective model are greater than that of the fully defective model.When the displacement is loaded to 20 mm,the stiffness degradation of the three models is equivalent.
文摘Aims: Cardiovascular disease (CVD) and periodontitis are both chronic inflammatory disorders which are highly prevalent in populations. Bacteria involved in the periodontal disease have been found to be cardiovascular risk markers. Periodontal pathogens may contribute to the atheroma pathogenesis. Severe periodontitis is correlated with the prevalence of bacteraemia, and poor periodontal status is an important risk factor for CVD. However, the association is unclear. If the association is causal, the periodontal therapy will lead to an attenuation of the effects on CVD. The study aimed to study if the periodontal intervention therapy presented therapeutic effects on CVD. Methods: English language literature on periodontal intervention therapy on CVD is causal or not. The literature revealed 62 papers associated with this study to investigate the relationship between periodontitis and CVD. Results: The literature supported the idea that periodontal infections had been associated with CVD. Certain periodontal therapy is associated with bacteraemia, and the prevalence of bacteraemia may arise from periodontal therapy and poor oral hygiene practices. Periodontal therapy not only presented therapeutic effects by reducing cytokine activity and C-response protein (CRP), but also caused bacteraemia transitorily. Effective antibiotic prophylaxis pre- or post-periodontal therapy presented some beneficial effects on bacteraemia or CVD. Conclusion: Severe periodontitis causes systemic inflammation and endothelial dysfunction, and goes beyond the oral cavity. Periodontal intervention would contribute to the prevention of atherosclerosis, and antibiotic prophylaxis would be helpful to decrease bacteraemia and reduce the onset of CVD.
基金financially supported by the National Natural Science Foundation of China(No.52205431)the CAS Interdisciplinary Innovation Team Project(No.JCTD-2020-10)。
文摘Oxygen is crucial in influencing the microstructure evolution of selective laser melted(SLMed)Ti–6Al–4V,significantly impacting its applicability in various sectors.Therefore,this study investigates the influnce of oxygen on microstructure evolution,particularlyα′martensite transformation and refinement mechanisms.Four alloys,Ti–6Al–4V–xO(x=0.11,0.16,0.21,and 0.25 wt%),were fabricated by the SLM process.The martensite start temperature(M_(s))of Ti–6Al–4V,as evaluated by computation,is 656.8°C,and oxygen was found to increase the M_(s) by about 10°C per 0.1 wt%.The SLMed alloy samples exhibit[001]_(β)growth texture along the build direction.Crystallographic analysis of martensite morphology suggests internal twinning on{1011}planes as the lattice invariant strain,which becomes more predominant with increasing oxygen content.Refinement of α′martensite plates by oxygen is due to increased lattice distortion,reduced prior β grain size,and oxygen segregation toβgrain boundaries.Our findings contribute to improving the understanding of the effect of oxygen on the transformation mechanism ofα′martensite during SLM of Ti–6Al–4V.
基金supported by the National Natural Science Foundation of China,Nos.81772453(to DX),81974358(to DX),81973157(to JZ),82173646(to JZ),82302866(to YZ)。
文摘Promoting synaptic plasticity and inducing functional reorganization of residual nerve fibers hold clinical significance for restoring motor function following spinal cord injury.Neuromagnetic stimulation targeting the nerve roots has been shown to improve motor function by enhancing nerve conduction in the injured spinal cord and restoring the synaptic ultrastructure of both the sensory and motor cortex.However,our understanding of the neurophysiological mechanisms by which nerve root magnetic stimulation facilitates motor function recovery in the spinal cord is limited,and its role in neuroplasticity remains unclear.In this study,we established a model of spinal cord injury in adult male Sprague–Dawley rats by applying moderate compression at the T10 vertebra.We then performed magnetic stimulation on the L5 nerve root for 3 weeks,beginning on day 3 post-injury.At day 22 post-injury,we observed that nerve root magnetic stimulation downregulated the level of interleukin-6 in the injured spinal cord tissue of rats.Additionally,this treatment reduced neuronal damage and glial scar formation,and increased the number of neurons in the injured spinal cord.Furthermore,nerve root magnetic stimulation decreased the levels of acetylcholine,norepinephrine,and dopamine,and increased the expression of synaptic plasticity-related m RNA and proteins PSD95,GAP43,and Synapsin II.Taken together,these results showed that nerve root magnetic stimulation alleviated neuronal damage in the injured spinal cord,regulated synaptic plasticity,and suppressed inflammatory responses.These findings provide laboratory evidence for the clinical application of nerve root magnetic stimulation in the treatment of spinal cord injury.
文摘The microstructure evolutions and nucleation mechanisms of GH4169G alloy were studied by optical microscope, electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). The hot compression tests were performed different imposed reductions in the range of true strain from 0.12 to 1.2 at the temperatures of 930 °-1050 ° with strain rates of 0.01 s^-1-l s^-1. It is found that cumulative and local misorientation increase firstly and then decrease when the strain is increased due to the progress of dynamic recrystallization (DRX). The low angle boundaries (LAGBs) rapidly develop to high angle boundaries (HAGBs) at relatively high deformation temperature or the low strain rate. There are three DRX mechanisms observed for GH4169 G alloy during hot deformation. Discontinuous dynamic recrystallization (DDRX) as the dominant mechanism for GH4169 G alloy is characterized by typical necklace structures and bulged-original boundaries. Besides, different deformation bands with dislocation cells formed in deformed matrix at low temperature and large strain, which indicates that continuous dynamic recrystallization (CDRX) contributed to the DRX process. The twin boundaries lost their coherent characteristics and provide sites for nucleation, which also accelerates the nucleation of DRX.
文摘By binding molecular probes that target tumor cells, gold nanoparticles (AuNPs) with superior characteristics have shown great potential in tumor molecular imaging studies. The non-invasive, high-resolution, and three-dimensional imaging of the targeted AuNPs within the tumor is desirable for both diagnosis and therapy. In this study, gold nanoflowers (AuNFs) are presented as a novel contrast agent for photoacoustic tomography (PAT). By binding to folic acid, the molecular probe, the tail-vein injected AuNFs concentrated within the tumor site in mice; this was clearly visualized by three-dimensional (3D) PAT imaging. In addition, toxicity assay proved that AuNFs were harmless to living cells and animals. Our results demonstrate that AuNFs have great potential in tumor molecular imaging.
文摘Flow behavior and processing map play important roles in the hot deformation process of titanium alloys. In this research, compression Gleeble tests have been carried out to investigate the stress-strain relationship at temperatures ranging from 700 to 1000 ℃ and strain rates ranging from 0.001 to 1 s-1 for ATI 425 titanium alloy. Arrhenius type constitutive equation was obtained to describe the compressive flow behavior with modification of additional deformation dead zone, friction model, temperature model and strain rate. The introduction of novel calculation method for α value in Arrhenius equation gives more accurate fitting than traditional one. Processing maps were drawn based on the distribution of dissipator co-content, and optimized deformation temperature and strain rate range obtained. It is proven to be accurate and effective through the experimental results. The microstructure analysis shows that more dynamic recrystallization can be achieved in the area with larger ηvalue on the processing map.
基金The authors acknowledge financial support from the National Basic Research Program of China (Nos.2013CB932601 and 2014CB239303) and the National Natural Science Foundation of China (No. 21133001).
文摘The development of highly efficient and earth-abundant oxygen evolution/ reduction reaction (OER/ORR) catalysts is essential for rechargeable metal-air batteries. Herein, cobalt-based hydroxide nanoparticles @ N-doping carbonic framework (CoOHCat@NCF) core-shell structures have been designed as highly stable and efficient OER/ORR bifunctional catalysts. The obtained composite shows enhanced catalytic activities and excellent stability in alkaline media. In the OER, a high turnover frequency (2.03 s^-1 at an overpotential of 0.36 V), low overpotential at high current density (100 mA.cm-2 requiring an overpotential of 0.38 V), and excellent stability (100 mA·cm^-2 for one week with no activity loss) have been achieved. Furthermore, although cobalt species-based catalysts are known as good ORR catalysts, their hybridization with NCF obtained from metal organic frameworks successfully enhanced their ORR activities. The efficient activity of CoOHCat@NCF as a bifunctional oxygen electrocatalyst can be ascribed to the core-shell structures stabilizing the active catalytic sites and the porous shell structure favoring electrocatalysis-related mass transport.
基金the support from National Key R&D Program of China(No.2016YFA0200800)the National Natural Science Foundation of China(Nos.61527818,61834007,61604165,61571430,61874130,61674160)Science and Technology Development Fund of Shanghai Institute of Technology。
文摘This paper reports a high-performance H2S gas sensing material that is made of ZnO nanowires(NWs)modified by an optimal amount of ZnS to form nano-hete rojunctions.Compared with the intrinsic ZnONWs,the three differently modified nano-heterostructure material ZnO-ZnS-x(x=5,10,15)shows significant improvement in sensing performance to H2S at the working temperatures of 100-400℃,especially in the low temperature range(<300℃).The chemiresistive sensor with ZnO-ZnS-10 sensingmaterial exhibits the largest response signal to H2S among all the other ZnO-ZnS-x(x=5,10,15,20)sensors.Its response signal to 5 ppm H2S at 150℃is about 2.7 times to that of the ZnO-NWs sensor.Besides,the ZnO-ZnS-10 sensor also features satisfactory selectivity and repeatability at 150℃.With the technical advantage attributed to the reduction of the redesigned band gap at the interface between ZnO and ZnS,the ZnO-ZnS hete ro structure sensor rather than the traditional ZnO-NWs sensor can be used for high-sensitivity application at low working temperature.
基金support from the National Natural Science Foundation of China(No.51701219)the Doctoral Scientific Research Foundation of Liaoning Province(No.20180540133)the Special Project on Information Technology of the Chinese Academy of Sciences(No.XXH13506–304)。
文摘The effects of heating rate on the alloy element partitioning and mechanical properties during the phase transformation ofα→βin Ti-6Al-4 V alloy under solution treatment have been investigated by the experiments and phase field simulations,which reveal the evolutions of microstructure and compositions at the non-equilibrium state and well verify the experimental results.The specific results indicate that the compositions measured through electron probe micro-analysis(EPMA)under a lower heating rate are close to the equilibrium ones corresponding to the solution temperature.Heating up to the target solution temperature,as the heating rate increases,the Al content decreases and V increases in the primaryα(α_(p))grain with a larger size,the volume fraction ofα_(p)increases and the composition gradient betweenα_(p)andβphases gets steeper.The interrelated relationship among the diffusion,compositions,solution temperature and free energy of the system has been discussed in detail.Moreover,increasing the heating rate(~20.0 K/min)may help to improve the mechanical properties of the alloy by mainly adjusting theα_(p)/β;volume fractions,α_(p)particle size and secondaryα(α_(p))size during the process of heating up to the solution temperature.These results may shed some light on the optimization of the knowledge-based heat treatment route.
基金supported by the National Basic Research Program of China (2011CB606404)the National Natural Science Foundation of China (51171195)GM Research Project
文摘The nucleation and propagation of h011]superdislocations in intermetallic TiAl were investigated using molecular dynamics simulations and static energetics calculation,as part of our systematic effort to understand the twining and dislocation behavior of alloys based on c-TiAl.It was found that compared to ordinary dislocations in disordered crystals,superdislocations in ordered TiAl lattice behave differently when sheared in the two opposite senses along[0"11]direction.This difference is due to the lower L10lattice symmetry compared with the face-centered cubic(fcc)lattice that it based on,with different yield stress and strain,and dislocation core dissociation and motion.Superdislocations nucleated in the form of loops dissociated in a planar manner into four Shockley partials separated by three kinds of faults:superlattice intrinsic stacking fault(SISF),anti-phase domain boundary(APB)and complex stacking fault(CSF),with partial separations depending on the sense of shearing and dislocation character.During loop expansion,the dislocation core changes both in width and dissociation manner depending on the character of the segment in the loop.The core contains four partials close to edge orientation,gradually changing to three fold near 60°,and finally into twofold dissociationaround 30°character.Superdislocations may have multiple critical resolved shear stresses(CRSS)for motion depending on dissociation and shearing sense even for the same slip system,with lower critical stress for the motion when SISF is in leading position.
文摘Exploration of heavy metals and organic pollutants, their leaching capacity along with health and environmental risks in contaminated industrial construction and demolition waste (ICDW) within a pesticide manufacturing plant were investigated. A maximum content of 90.8 mg·kg-1 Cd was found present in the wastes, which might originate from phosphorus rocks and industrial sulfuric acid used in pesticide production processes. An average concentration of 979.8 mg·kg-1 dichlorovos and other 11 organophosphorus pesticide were also detected. Relatively high leaching rates of around 4.14‰ were obtained from laboratory simulated ICDW using both glacial acetic acidsodium hydroxide and deionized water. Pesticide pollutants had the strongest tendency to retaining on dry bricks (leaching rate 1.68 9‰) compared to mortar-coatings, etc. due to their different physical characteristics and octanol-water partioning coefficient. Mobility of pesticide from on-site ICDW by water was spatially correlated to waste types, process sections and human activities, with a flux of leaching rate between 5.9‰ to 27.4%. Risk-based corrective action (RBCA) model was used to simulate the risk of contaminated ICDW debris randomly scattered. Oral and demlal ingestion amount by local workers was 9.8 × 10-3 and 1.9 × 10-2 mg.(kg-d)-1, respectively. Potential leaching risk to aquatic systems exceeded the limit for nearly 75% waste. Environmental and health risk exceedance was found in most ICDW, while the risk value of the most severely contaminated brick waste was 660 times beyond critical level. Implications for waste management involving construction and deconstruction work, waste transferring and regulation supplying were also provided.
基金by research grants by National Basic Research Program of China(973 Program Grant No.2014CB965001)National Natural Science Foundation of China(#81271419)+2 种基金Innovative Research Groups of the National Natural Science Foundation of China(#81221001)Joint Research Fund for Overseas Chinese,Hong Kong and Macao Young Scientists of the National Natural Science Foundation of China(#81329002)National Institutes of Health:R01 NS 41858–01,R01 NS 061642–01,P20 RR15635-01,the State of Nebraska,DHHS-LB606 Stem Cell 2009–10(JZ),LB606 Stem Cell-2010-10(CT).Julie Ditter,Lenal Bottoms,Johna Belling,Jaclyn Ostronic and Robin Taylor provided outstanding administrative and secretarial support.
文摘Alzheimer’s disease(AD)is a prominent form of dementia,characterized by aggregation of the amyloidβ-peptide(Aβ)plaques and neurofibrillary tangles,loss of synapses and neurons,and degeneration of cognitive functions.Currently,although a variety of medications can relieve some of the symptoms,there is no cure for AD.Recent breakthroughs in the stem cell field provide promising strategies for AD treatment.Stem cells including embryonic stem cells(ESCs),neural stem cells(NSCs),mesenchymal stem cells(MSCs),and induced pluripotent stem cells(iPSCs)are potentials for AD treatment.However,the limitation of cell sources,safety issues,and ethical issues restrict their applications in AD.Recently,the direct reprogramming of induced neural progenitor cells(iNPCs)has shed light on the treatment of AD.In this review,we will discuss the latest progress,challenges,and potential applications of direct reprogramming in AD treatment.
基金financially supported by the National Key Research and Development Program of China(Nos.2016YFB0701304 and 2016YFC0304200)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDC01040100)+1 种基金the Special Project on Information Technology of the Chinese Academy of Sciences(No.XXH13506-304)the CAS-Shenyang Supercomputing Center and the Doctoral Scientific Research Foundation of Liaoning Province(No.20180540133)。
文摘Variant selection under specific applied stresses during precipitation of a plates from prior-βmatrix in Ti-6 Al-4 V was investigated by 3 D phase field simulations.The model incorporates the Burgers transformation path fromβto a phase,with consideration of interfacial energy anisotropy,externally applied stresses and elastic interactions among a variants andβmatrix.The Gibbs free energy and atomic mobility data are taken from available thermodynamic and kinetic databases.It was found that external stresses have a profound influence on variant selection,and the selection has a sensitive dependence,as evidenced by both interaction energy calculations and phase field simulations.Compared with normal stresses,shear stresses applied in certain directions were found more effective in accelerating the transformation,with a stronger preference to fewer variants.The volume fractions of various a variants and the final microstructure were determined by both the external stress and the elastic interaction among different variants.The a clusters formed by variants with Type2 misorientation([11-20]/60°)relation were found more favored than those with Type4([-1055-3]/63.26°)under certain applied tensile stress such as along<111>β.The mechanical properties of different microstructures from our phase field simulation under different conditions were calculated for different loading conditions,utilizing crystal plastic finite element simulation.The mechanical behavior of the various microstructures from phase field simulation can be evaluated well before the alloys are fabricated,and therefore it is possible to select microstructure for optimizing the mechanical properties of the alloy through thermomechanical processing based on the two types of simulations.
基金National Natural Science Foundation of China(No.51701209)National Key Research and Development Program of China(Nos.2016YFB0701304)。
文摘Large size polysynthetically twinned crystals of Ti-46 Al-8 Nb alloy with a parallel lamellar microstructure were successfully prepared using a Ti-43 Al-3 Si seed by our new operation.A large amount of columnar B2 phase paralleling to the growth direction was found in the final lamellar microstructure.Higher growth rate(>30 mm/h)led to the failure of seeding process.Based on these results,a new mechanism is proposed to describe the seeding process of the hypo-peritectic Ti Al alloys.The peritecticαphase is suggested to directly nucleate from the melt,and then act as nucleus for transformedαphase in the subsequentβtoαtransformation.At the higher growth rate,the appearance ofβphase secondary dendrites and homogeneous nucleation lead to the failure of seeding process.High Nb addition leads to a large amount of residualβphase,and theseβdendrites finally evolve into B2 phase.The room temperature tensile elongation was measured to be 11.9-18.5%for Ti-46 Al-8 Nb PST crystals,which is the highest ever reported value for Ti Al based alloys.