Jianguo Li
Shanghai Jiaotong University, Materials Science and Engineering, Faculty Member
ABSTRACT This research discussed how to synthesize submicrometer-sized TiC particulate reinforcement in the molten aluminum melt at low temperature via combustion synthesis by using in situ casting technique. A high temperature preheating... more
ABSTRACT This research discussed how to synthesize submicrometer-sized TiC particulate reinforcement in the molten aluminum melt at low temperature via combustion synthesis by using in situ casting technique. A high temperature preheating treatment of Al-Ti-C pellets was carried out, by which the thermal explosion reaction of the pellets could take place in the pure aluminum melt at 750 degrees C. The synthesizing temperature of TiC particles was reduced by at least 150 degrees C compared with the conventional methods. In situ formed TiC particles were spherical in shape and were smaller than 1 mu m in size due to the low melting temperature. The emergence of liquid aluminum phase led to the generation and accumulation of plenty of heat in the pellet in a short time due to the reactive diffusion of Al(l)-Ti(s). The formation mechanism of the submicrometer-sized TiC particles in the molten aluminum at low temperature was discussed in this research.
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... amorphous rods exhibit large glass-forming ability (GFA) and hard magnetic behavior with coercivity ... composed of a fine-grained eutectic structure with an arrangement of two phases: dendritic ... The Fe-rich phase exhibits a large... more
... amorphous rods exhibit large glass-forming ability (GFA) and hard magnetic behavior with coercivity ... composed of a fine-grained eutectic structure with an arrangement of two phases: dendritic ... The Fe-rich phase exhibits a large coercivity at room temperature and is responsible ...
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A study of the microstructure and martensitic transformation behavior of a new ferromagnetic shape memory Co46Ni27Ga27 alloys at different annealing temperatures (700–1200°C) and cooling conditions (water quenching, air and furnace... more
A study of the microstructure and martensitic transformation behavior of a new ferromagnetic shape memory Co46Ni27Ga27 alloys at different annealing temperatures (700–1200°C) and cooling conditions (water quenching, air and furnace cooling) was carried out using optical microscopy (OM), energy dispersive spectrometer (EDS), X-ray diffraction analysis (XRD) and differential scanning calorimeter (DSC). The results show that the wide range starting martensitic
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Coronaviruses (CoVs) continuously threaten human health. However, to date, the evolutionary mechanisms that govern CoV strain persistence in human populations have not been fully understood. In this study, we characterized the evolution... more
Coronaviruses (CoVs) continuously threaten human health. However, to date, the evolutionary mechanisms that govern CoV strain persistence in human populations have not been fully understood. In this study, we characterized the evolution of the major antigen-spike (S) gene in the most prevalent human coronavirus (HCoV) OC43 using phylogenetic and phylodynamic analysis. Among the five known HCoV-OC43 genotypes (A to E), higher substitution rates and dN/dS values as well as more positive selection sites were detected in the S gene of genotype D, corresponding to the most dominant HCoV epidemic in recent years. Further analysis showed that the majority of substitutions were located in the S1 subunit. Among them, seven positive selection sites were chronologically traced in the temporal evolution routes of genotype D, and six were located around the critical sugar binding region in the N-terminal domain (NTD) of S protein, an important sugar binding domain of CoV. These findings suggest ...
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Human coronavirus (HCoV) OC43 is the most prevalent HCoV in respiratory tract infections. Its molecular epidemiological characterization, particularly the genotyping, was poorly addressed. The full-length spike (S), RNA-dependent RNA... more
Human coronavirus (HCoV) OC43 is the most prevalent HCoV in respiratory tract infections. Its molecular epidemiological characterization, particularly the genotyping, was poorly addressed. The full-length spike (S), RNA-dependent RNA polymerase (RdRp), and nucleocapsid (N) genes were amplified from each respiratory sample collected from 65 HCoV-OC43-positive patients between 2005 and 2012. Genotypes were determined by phylogenetic analysis. Recombination was analyzed based on full-length viral genome sequences. Clinical manifestations of each HCoV genotype infection were compared by reviewing clinical records. Sixty of these 65 samples belong to genotypes B, C and D. The remaining five strains had incongruent positions in the phylogenetic trees of the S, RdRp and N genes, suggesting a novel genotype emerging, designated as genotype E. Whole genome sequencing and bootscan analysis indicated that genotype E is generated by recombination between genotypes B, C and D. Temporal analysis ...
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ABSTRACT A developed approach for fabricating in situ Al3Ti/Al composites via ultrasound assisted direct reaction between solid Ti powers and liquid Al at 780 degrees C was proposed in this research. In situ formed Al3Ti particles were... more
ABSTRACT A developed approach for fabricating in situ Al3Ti/Al composites via ultrasound assisted direct reaction between solid Ti powers and liquid Al at 780 degrees C was proposed in this research. In situ formed Al3Ti particles were blocky in morphology, and the size of most Al3Ti particles was in the range of 2-7 mu m. The effects of ultrasonic vibration on the microstructure and fabricating process of in situ Al3Ti/Al composites were also discussed by comparing the ultrasonic treated sample and the contrast sample without ultrasonic treatment. In addition, a reaction-peeling model was suggested to explain the formation mechanism of small blocky Al3Ti particles. Crown Copyright
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Research Interests:
A new directional solidification (DS) technique, combining electromagnetic shaping with liquid metal cooling, is established to confine and shape liquid metal by an electromagnetic field without the mold and carry out DS with a... more
A new directional solidification (DS) technique, combining electromagnetic shaping with liquid metal cooling, is established to confine and shape liquid metal by an electromagnetic field without the mold and carry out DS with a high-temperature gradient. The motion of the sample, heat radiation, and especially the material-property difference between the solid and the liquid, are considered for electromagnetic heating. Thereafter, a non-linear temperature model is established to calculate the position of the solid/liquid interface with respect to the furnace, the height of liquid metal and the temperature distribution in stainless-steel samples. The results of calculation are in good agreement with experimental measurements. On the basis of the model, experimental parameters, such as the intensity of cooling, and the current in the induction coils, can be further optimized so as to control the morphology of the solid/liquid interface, the temperature gradient and the axial temperature distribution in the liquid metal. A FEM approach is developed in this paper.
Research Interests: Materials Engineering, Mechanical Engineering, Manufacturing Engineering, Stainless Steel, High Temperature, and 7 moreElectromagnetic Field, Temperature Distribution, Temperature Gradient, Finite Temperature Field Theory, Liquid-liquid and liquid-solid interface, Experimental Measurement, and Material Properties
The concept of the dual-frequency electromagnetic (EM) shaping of liquid metal is first presented. The experiment of dual-frequency with 350 and 50kHz EM shaping is successfully carried out. It is shown that the process of dual-frequency... more
The concept of the dual-frequency electromagnetic (EM) shaping of liquid metal is first presented. The experiment of dual-frequency with 350 and 50kHz EM shaping is successfully carried out. It is shown that the process of dual-frequency with 350 and 50kHz EM shaping is implemented more easily than that of dual-high frequency with 350 and 200kHz EM shaping, because the EM
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Using electromagnetic levitation melting combining with fluxing method, the Fe83Ga17 alloys were undercooled up to 173K through superheating–cooling cycles. The results showed that the microstructure was closely related to the... more
Using electromagnetic levitation melting combining with fluxing method, the Fe83Ga17 alloys were undercooled up to 173K through superheating–cooling cycles. The results showed that the microstructure was closely related to the undercooling. When the undercooling was lower than 53K, the structures consisted of coarse dendrites and some dark particles in interdendrite. With the increase of undercooling, the solidified microstructures tended to
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Ca3−xDyxCo4O9+δ (x=0, 0.15, 0.3 and 0.45) polycrystalline samples have been prepared using a sol–gel process followed by SPS sintering. Their thermoelectric properties have been carefully studied from room temperature to 1000K. The... more
Ca3−xDyxCo4O9+δ (x=0, 0.15, 0.3 and 0.45) polycrystalline samples have been prepared using a sol–gel process followed by SPS sintering. Their thermoelectric properties have been carefully studied from room temperature to 1000K. The substitution of Dy for Ca results in increasing of both thermopower and electrical resistivity, which could be attributed to the decreasing of carrier concentrations. The Dy substituted samples
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The effects of Co on the martensitic transformation and magnetic properties of NiFeGa magnetic shape memory alloys were investigated. An unusual phenomenon of one martensitic transformation and two intermartensitic transformations in... more
The effects of Co on the martensitic transformation and magnetic properties of NiFeGa magnetic shape memory alloys were investigated. An unusual phenomenon of one martensitic transformation and two intermartensitic transformations in the differential ...
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We report the evolution of high temperature thermoelectric properties of SrTiO3 thin films doped with Nb and oxygen vacancies. Structure-property relations in this important thermoelectric oxide are elucidated and the variation of... more
We report the evolution of high temperature thermoelectric properties of SrTiO3 thin films doped with Nb and oxygen vacancies. Structure-property relations in this important thermoelectric oxide are elucidated and the variation of transport properties with dopant concentrations is discussed. Oxygen vacancies are incorporated during growth or annealing in Ar/H2 above 800 K. An increase in lattice constant due to the inclusion of Nb and oxygen vacancies is found to result in an increase in carrier density and electrical conductivity with simultaneous decrease in carrier effective mass and Seebeck coefficient. The lattice thermal conductivity at 300 K is found to be 2.22 W m(-1) K(-1), and the estimated figure of merit is 0.29 at 1000 K.