Whole genome sequencing data of the submerged macrophytes growth promoting and aerobic denitrifying bacterium Bacillus velezensis NBNZ-0060.

The Bacillus velezensis strain NBNZ-0060 was isolated from the bottom sediment samples of the lake Jin in Wuhan, China. This strain is an aerobic denitrifying bacterium and able to promote growth of submerged macrophytes. The 3,929,784 bp entire genome contains 3,781 coding sequences (CDS), 27 rRNAs, 85 tRNAs, 5 ncRNAs, with an average G + C content of 46.5%. The average nucleotide identity and digital DNA-DNA values between strain NBNZ-0060 and Bacillus velezensis NRRL B-41580T were 98.28% and 84.5%, respectively. The genome data have been deposited in NCBI with the accession number CP133277.1.

Scattering of a radially polarized Bessel beam by a PEMC sphere: photonic nanojet and bottle beam formation.

The scattering of a radially polarized (r p) Bessel vortex and nonvortex beam by a perfect electromagnetic conductor (PEMC) sphere is studied based on the generalized Lorenz-Mie theory. The electric and magnetic fields of the incident arbitrary-shaped polarized beams are constructed using vector spherical wave functions (VSWFs) and beam shape coefficients. The analytical expression of the scattered field is expanded using VSWFs and scattering coefficients, which are derived by considering PEMC boundary conditions. The expression of the normalized dimensionless far-field scattering intensity (NDFSI) is also defined and derived. The photonic nanojet (PNJ) and the "bottle beam" generated by the interaction between the PEMC sphere and the vortex and nonvortex Bessel beam under r p are emphasized in this paper. Moreover, the intensity and directivity of NDFSI are also considered. It has been found that the generation of the PNJ and the "bottle beam" is determined by the half-cone angle α 0 of the r p Bessel beam and admittance parameter M of the PEMC sphere. Furthermore, the influence of M, α 0, and integer order l of the Bessel beam on the intensity and distribution of NDFSI is also discussed. The findings are important in the research on meta-materials and promising prospects in microwave engineering, antenna engineering, imaging, subwavelength focusing, optical radiation force, and torque.

Investigation on the Attainment of High-Density 316L Stainless Steel with Selective Laser Sintering.

Due to the low density of the green part produced by selective laser sintering (SLS), previous reports mainly improve the sample's density through the infiltration of low-melting metals or using isostatic pressing technology. In this study, the feasibility of preparing high-density 316L stainless steel using 316L and epoxy resin E-12 as raw materials for SLS combined with debinding and sintering was investigated. The results indicated that in an argon atmosphere, high carbon and oxygen contents, along with the uneven distribution of oxygen, led to the formation of impurity phases such as metal oxides, including Cr2O3 and FeO, preventing the effective densification of the sintered samples. Hydrogen-sintered samples can achieve a high relative density exceeding 98% without losing their original design shape. This can be attributed to hydrogen's strong reducibility (effectively reducing the carbon and oxygen contents in the samples, improving their distribution uniformity, and eliminating impurity phases) and hydrogen's higher thermal conductivity (about 10 times that of argon, reducing temperature gradients in the sintered samples and promoting better sintering). The microstructure of the hydrogen-sintered samples consisted of equiaxed austenite and ferrite phases. The samples exhibited the highest values of tensile strength, yield strength, and elongation at 1440 °C, reaching 513.5 MPa, 187.4 MPa, and 76.1%, respectively.

Investigation on Sub-Solvus Recrystallization Mechanisms in an Advanced γ-γ' Nickel-Based Superalloy GH4151.

Sub-solvus dynamic recrystallization (DRX) mechanisms in an advanced γ-γ' nickel-based superalloy GH4151 were investigated by isothermal compression experiments at 1040 °C with a strain rate of 0.1 s-1 and various true strain of 0.1, 0.3, 0.5, and 0.7, respectively. This has not been reported in literature before. The electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) technology were used for the observation of microstructure evolution and the confirmation of DRX mechanisms. The results indicate that a new dynamic recrystallization mechanism occurs during hot deformation of the hot-extruded GH4151 alloy. The nucleation mechanism can be described as such a feature, that is a primary γ' (Ni3(Al, Ti, Nb)) precipitate embedded in a recrystallized grain existed the same crystallographic orientation, which is defined as heteroepitaxial dynamic recrystallization (HDRX). Meanwhile, the conventional DRX mechanisms, such as the discontinuous dynamic recrystallization (DDRX) characterized by bulging grain boundary and continuous dynamic recrystallization (CDRX) operated through progressive sub-grain merging and rotation, also take place during the hot deformation of the hot-extruded GH4151 alloy. In addition, the step-shaped structures can be observed at grain boundaries, which ensure the low-energy surface state during the DRX process.

Superplastic Deformation and Dynamic Recrystallization of a Novel Disc Superalloy GH4151.

The superplastic deformation of a hot-extruded GH4151 billet was investigated by means of tensile tests with the strain rates of 10-4 s-1, 5 × 10-4 s-1 and 10-3 s-1 and at temperatures at 1060 °C, 1080 °C and 1100 °C. The superplastic deformation of the GH4151 alloy was reported here for the first time. The results reveal that the uniform fine-grained GH4151 alloy exhibited an excellent superplasticity and high strain rate sensitivity (exceeded 0.5) under all experimental conditions. It was found that the increase of strain rate resulted in an increased average activation energy for superplastic deformation. A maximum elongation of 760.4% was determined at a temperature of 1080 °C and strain rate of 10-3 s-1. The average activation energy under different conditions suggested that the superplastic deformation with 1 × 10-4 s-1 in this experiment is mainly deemed as the grain boundary sliding controlled by grain boundary diffusion. However, with a higher stain rate of 5 × 10-4 s-1 and 1 × 10-3 s-1, the superplastic deformation is considered to be grain boundary sliding controlled by lattice diffusion. Based on the systematically microstructural examination using optical microscope (OM), SEM, electron backscatter diffraction (EBSD) and TEM techniques, the failure and dynamic recrystallization (DRX) nucleation mechanisms were proposed. The dominant nucleation mechanism of dynamic recrystallization (DRX) is the bulging of original grain boundaries, which is the typical feature of discontinuous dynamic recrystallization (DDRX), and continuous dynamic recrystallization (CDRX) is merely an assistant mechanism of DRX. The main contributions of DRX on superplasticity elongation were derived from its grain refinement process.

Improvement of ZrC/Zr Coating on the Interface Combination and Physical Properties of Diamond-Copper Composites Fabricated by Spark Plasma Sintering.

In this study, diamond-copper composites were prepared with ZrC/Zr-coated diamond powders by spark plasma sintering. The magnetron sputtering technique was employed to coat the diamond particles with a zirconium layer. After heat treatment, most of the zirconium reacted with the surface of diamond and was transformed into zirconium carbide. The remaining zirconium on the zirconium carbide surface formed the outer layer. Owing to the method used to produce the ZrC/Zr-coated diamond in this study, the maximum thermal conductivity (TC) of 609 W·m-1·K-1 was obtained for 60 vol. % diamond-copper composites and the corresponding coefficient of thermal expansion (CTE) reached as low as 6.75 × 10-6 K-1. The bending strength of 40 vol. % ZrC/Zr-coated diamond-copper composites reached 255.95 MPa. The thermal and mechanical properties of ZrC/Zr-coated diamond-copper composites were substantially superior to those of uncoated diamond particles. Excellent properties can be attributed to the strengthening of the interfacial combination and the decrease in the interfacial thermal resistance due to the improvement associated with the ZrC/Zr coating. Theoretical analysis was also proposed to compare the thermal conductivities and CTE of diamond-copper composites fabricated with these two kinds of diamond powders.

Mesporous 3C-SiC Hollow Fibers.

In the present work, for the first time, we reported the exploration of mesoporous 3C-SiC hollow fibers via single-spinneret electrospinning of polyureasilazane (PSN) and polyvinylpyrrolidone (PVP) solution followed by high-temperature pyrolysis treatment. The resultant products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and N2 adsorption. The as-prepared hollow fibers with totally mesoporous walls were uniformly sized in diameter and high purity in morphology. They were composed of single-crystalline 3C-SiC nanoparticles with a surface area of 21.75 m2/g and average pore diameter of ~34 nm. The PSN concentration played a determined role on the formation of hollow fibers rather than the conventional solid counterparts, enabling their growth in a tunable manner. A possible mechanism was proposed for the formation of mesoporous SiC hollow fiber.

Hollow core-shell structured Si/C nanocomposites as high-performance anode materials for lithium-ion batteries.

Hollow core-shell structured Si/C nanocomposites were prepared to adapt for the large volume change during a charge-discharge process. The Si nanoparticles were coated with a SiO2 layer and then a carbon layer, followed by etching the interface SiO2 layer with HF to obtain hollow core-shell structured Si/C nanocomposites. The Si nanoparticles are well encapsulated in a carbon matrix with an internal void space between the Si core and the carbon shell. The hollow core-shell structured Si/C nanocomposites demonstrate a high specific capacity and excellent cycling stability, with capacity decay as small as 0.02% per cycle. The enhanced electrochemical performance can be attributed to the fact that the internal void space can accommodate the volume expansion of Si during lithiation, thus preserving the structural integrity of electrode materials, and the carbon shell can increase the electronic conductivity of the electrode.

Preparation and properties of porous Ti-10Mo alloy by selective laser sintering.

In this study, porous Ti-10Mo alloy was prepared from a mixture of titanium, molybdenum and epoxy resin powders by selective laser sintering preforming, debinding and sintering at 1200 °C under a pure argon atmosphere. The influence of sintering process on the porous, microstructural and mechanical properties of the porous alloy was discussed. The results indicate that the pore characteristic parameters and mechanical properties mainly depend on the holding time at 1200 °C, except that the maximum strain keeps at about 45%. The matrix microstructure is dominated by α phase with a small quantity of ß phase at room temperature. As the holding time lengthens from 2 to 6h, the average pore size and the porosity decrease from 180 to 50 µm and from 70 to 40%, respectively. Meanwhile, the Young's modulus and the compressive yield strength increase in the ranges of 10-20 GPa and 180-260 MPa, respectively. Both the porous structure and the mechanical properties of the porous Ti-10Mo alloy can be adjusted to match with those of natural bone.