Kinetics and numerical simulation of self-propagating high-temperature synthesis in Ti–Cr–Al–C systems

In this paper, Ti–Cr–Al–C materials were investigated by self-propagating high-temperature synthesis（SHS） according to the experimental study and numerical simulation results. The highest adiabatic combustion temperature Tadof 2,467.45 K indicates that the2Ti–0Cr–Al–C is the highest exothermic reaction system in the Ti–Cr–Al–C system. The adiabatic combustion temperature decreases with the increase of the Cr content. And a higher exothermal reaction would result in higher porosity which is induced by the high temperature and pressure of C reducing atmosphere and Al vapor. Combustion characterization of the products shows that the geometrical alternating layers result in the high exothermal reaction and flame-front propagating velocity. The higher the Tadis, the thinner the layer is. To demonstrate the process of the microscopic characterization and show the detailed combustion process closed to the experimental observations, the flame-front propagating velocity and temperature distribution were simulated numerically.

An efficient TILLING platform for cultivated tobacco

Targeting-induced local lesions in genomes(TILLING)is a powerful reverse-genetics tool that enables high-throughput screening of genomic variations in plants.Although TILLING has been developed for many diploid plants,the technology has been used in very few polyploid species due to their genomic complexity.Here,we established an efficient capillary electrophoresis-based TILLING platform for allotetraploid cultivated tobacco(Nicotiana tabacum L.)using an ethyl methanesulfonate(EMS)-mutagenized population of 1,536 individuals.We optimized the procedures for endonuclease preparation,leaf tissue sampling,DNA extraction,normalization,pooling,PCR amplification,heteroduplex formation,and capillary electrophoresis.In a test screen using seven target genes with eight PCR fragments,we obtained 118 mutants.The mutation density was estimated to be approximately one mutation per 106kb on average.Phenotypic analyses showed that mutations in two heavy metal transporter genes,HMA2S and HMA4T,led to reduced accumulation of cadmium and zinc,which was confirmed independently using CRISPR/Cas9 to generate knockout mutants.Our results demonstrate that this powerful TILLING platform(available at http://www.croptilling.org)can be used in tobacco to facilitate functional genomics applications.

Formation of M_(n+1)AX_n phases in Ti–Cr–Al–C systems by self-propagating high-temperature synthesis

In this paper, phase composition of the Mn＋l- AXn phases by self-propagating high-temperature synthesis （SHS） was determined using Ti, Cr, A1, and carbon black as raw materials. And, phase composition and micro- structures of the Mn＋1AXn phases-contained bulk by SHS with the pseudo-hot isostatic pressing （SHS/PHIP） were investigated in Ti-Cr-AI-C systems raw materials. Riet- veld XRD refinement was introduced to study the lattice parameters and phase composition of the resultant phases from the SHSed and SHS/PHIPed samples. Ti2A1Cx, Ti3A1C2, and Cr2A1Cx by SHS were detected in the Ti-Cr- A1-C systems, as well as the binary carbide of TiC and intermetallics. The mechanical properties of the synthe- sized bulk samples were determined, exhibiting a high strength and toughness compared with the typical mono- lithic Mn＋1AXn phase ceramics. It is indicated that the samples prepared by SHS/PHIP are identified to be a strategy for improving the mechanical properties of monolithic Mn＋1AXn phase.

Oscillatory-like expansion of a Fermionic superfluid

We study the expansion behaviors of a Fermionic superfluid in a cigar-shaped optical dipole trap for the whole BEC-BCS crossover and various temperatures.At low temperature(0:06(1)T_F),the atom cloud undergoes an anisotropic hydrodynamic expansion over 30 ms,which behaves like oscillation in the horizontal plane.By analyzing the expansion dynamics according to the superfluid hydrodynamic equation,the effective polytropic index y of Equation-of-State(EoS)of Fermionic superfluid is extracted.The y values show a non-monotonic behavior over the BEC-BCS crossover,and have a good agreement with the theoretical results in the unitarity and BEC side.The normalized quasi-frequencies of the oscillatory expansion are measured,which drop significantly from the BEC side to the BCS side and reach a minimum value of 1.73 around 1/k_Fa=-0:25.Our work improves the understanding of the dynamic properties of strongly interacting Fermi gas.