Meng P.,Bengbu University
International Journal of Advanced Manufacturing Technology | Year: 2015
Monolayer brazed grinding wheels were prepared using polycrystalline diamond grains, Ni-Cr-B-Si brazing alloy, and commercial Q235A steel with the brazing temperature 1000 °C and the holding time 5 min. The microstructure and element distribution of joint interface was studied through scanning electron microscope and energy dispersive X-ray spectroscope, respectively. Grinding performance of wheels was evaluated during grinding alumina specimen. The fracture of polycrystalline diamond grains with the embedding depth of 50 and 70 % was studied quantitatively. The results show that good joint interface was formed among polycrystalline diamond grains, Ni-Cr-B-Si brazing alloy, and Q235A steel through element diffusion and chemical reaction during brazing. Chemical resultants Cr3C2 and Cr7C3 formed within joint interface between polycrystalline diamond grain and Ni-Cr-B-Si brazing alloy; meanwhile, the growth of Cr3C2 has an orientation relationship with element arrangement of diamond surface. Compared with single crystal diamond grinding wheel, the polycrystalline diamond grinding wheel has exhibited evident advantages according to the grinding force and force ration (tangential grinding force Ft / normal grinding force Fn). The Fn and Ft is 21.69 and 7.23 N with the expositing high of 50 % and 5.16 and 1.72 N with the expositing high of 70 % respectively, when polycrystalline diamond grain fracture takes place. The failure mechanism of brazed polycrystalline diamond grains grinding wheel is diamond fracture. © 2015 Springer-Verlag London
Ouyang L.-L.,Shanghai Ocean University |
Li H.,Bengbu University |
Yan X.-J.,Ningbo University |
Xu J.-L.,Ningbo University |
Zhou Z.-G.,Shanghai Ocean University
Frontiers in Plant Science | Year: 2016
To analyze the contribution of glycerol-3-phosphate acyltransferase (GPAT) to the first acylation of glycerol-3-phosphate (G-3-P), the present study focused on a functional analysis of the GPAT gene from Lobosphaera incisa (designated as LiGPAT). A full-length cDNA of LiGPAT consisting of a 1,305-bp ORF, a 1,652-bp 5′-UTR, and a 354-bp 3′-UTR, was cloned. The ORF encoded a 434-amino acid peptide, of which 63 residues at the N-terminus defined a chloroplast transit peptide. Multiple sequence alignment and phylogeny analysis of GPAT homologs provided the convincible bioinformatics evidence that LiGPAT was localized to chloroplasts. Considering the conservation of His among the G-3-P binding sites from chloroplastidial GPATs and the substitution of His by Arg at position 195 in the LiGPAT mature protein (designated mLiGPAT), we established the heterologous expression of either mLiGPAT or its mutant (Arg195His) (sdmLiGPAT) in the GPAT-deficient yeast mutant gat1Δ. Lipid profile analyses of these transgenic yeasts not only validated the acylation function of LiGPAT but also indicated that the site-directed mutagenesis from Arg195 to His led to an increase in the phospholipid level in yeast. Semi-quantitative analysis of mLiGPAT and sdmLiGPAT, together with the structural superimposition of their G-3-P binding sites, indicated that the increased enzymatic activity was caused by the enlarged accessible surface of the phosphate group binding pocket when Arg195 was mutated to His. Thus, the potential of genetic manipulation of GPAT to increase the glycerolipid level in L. incisa and other microalgae would be of great interest. © 2016 Ouyang, Li, Yan, Xu and Zhou.
Zhang H.,Bengbu University
Computers and Mathematics with Applications | Year: 2015
In this paper, by constructing an objective function and using the gradient search, full-rank and reduced-rank gradient-based algorithms are suggested for solving generalized coupled Sylvester matrix equations. It is proved that the reduced-rank iterative algorithm is convergent for proper initial iterative values. By analyzing the spectral radius of the related matrices, the convergence properties are studied and the optimal convergence factor of the reduced-rank algorithm is determined. The relationship between the reduced-rank algorithm and the full-rank algorithm is discussed. Consequently, the computation load can be reduced greatly for solving a class of matrix equation. A numerical example is provided to illustrate the effectiveness of the proposed algorithms and testify the conclusions suggested in this paper. © 2015 Elsevier Ltd. All rights reserved.
Qian S.,Nanjing Agricultural University |
Qian S.,Bengbu University |
Lu H.,Nanjing Agricultural University |
Meng P.,Nanjing Agricultural University |
And 4 more authors.
Bioresource Technology | Year: 2015
The effect of inulin on the production of bacillomycin D and the levels of mRNA of bacillomycin D synthetase genes: bmyA (BYA), bmyB (BYB), bmyC (BYC), the thioesterase gene (TE) and regulating genes: AbrB, ComA, DegU, PhrC, SigmaH and Spo0A in Bacillus subtilis fmbJ were investigated. The production of bacillomycin D was enhanced with the increase of biomass concentration. The maximum production and productivity of bacillomycin D were found to be 1227.49. mg/L and 10.23. mg/L. h. Inulin significantly improved the expression of bacillomycin D synthetase genes: bmyA (BYA), bmyB (BYB), bmyC (BYC) and the thioesterase gene (TE). Also, inulin up-regulated ComA, DegU, SigmaH and Spo0A and therefore promoted the high production of bacillomycin D. Our results provided a practical approach for efficient production of bacillomycin D and a meaningful explanation for regulatory mechanism of bacillomycin D biosynthesis. © 2014 Elsevier Ltd.
Ge J.,Anhui University |
Ge J.,Bengbu University |
Xiao J.,Anhui University |
Liu L.,Anhui University |
And 2 more authors.
Journal of Porous Materials | Year: 2016
Well dispersed magnetic Fe3O4 decorated porous melamine-based covalent organic frameworks (M-COFs) were facilely fabricated through a microwave-assisted process. The result showed that magnetic M-COFs possess large surface areas of 344–600 m2 g−1 and good magnetic separation performance (MS = 0.75–3.59 emu g−1). Adsorption properties were preliminarily tested by the adsorptive removal of heavy metal ions from waste water. Remarkably, the as-synthesized Fe3O4/M-COFs display highly selective adsorption of Hg2+ with high adsorption capacity (97.65 mg g−1). This highly selective removal of Hg2+ was caused by the high density of N group in M-COFs. In addition, this selective adsorption of Hg2+ was not interfered with other metal ions such as Na+, Cd2+, Zn2+, Ni2+, Pb2+, Mg2+ and Cr3+. © 2016 Springer Science+Business Media New York