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Fe-6.5wt%Si steel is an excellent soft magnetic material due to the near-zero magnetostriction and low core losses. In this study, a 0.3 mm-thick grain-oriented 6.5wt%Si steel sheet was produced by a novel strip casting and two-stage rolling. The microstructure and texture evolution were investigated with a special emphasis on the nucleation and growth of Goss grains. The thin normalized strip was composed of large columnar grains and small equiaxed grains. During intermediate annealing, Goss grains nucleated in the shear bands of the deformed //ND grains, and the deformed {111} grains provided most of the nucleation sites. After primary annealing, the Goss grains distributed across the entire thickness, which was different from the conventional rolling route. The fraction of high-angle boundaries (20°-45°) surrounding the Goss grains was apparently higher than those of the matrix grains, which promoted the abnormal growth of the Goss grains during secondary recrystallization.

A Fe-1.3% Si non-oriented silicon steel strip was produced by twin-roll strip casting process, and subsequently treated with cold rolling and annealing. The effect of heating rates on the recrystallization and precipitation behavior of second phase particles (AlN and MnS) was investigated by MMS-200 thermal mechanical simulator. It was found that the recrystallization area fraction decreased obviously with the increase of heating rate. At the heating rate of 5 °C/s, the recrystallization rate gradually decreased with the extension of holding time, but it increased at the rapid heating rates. The particle’s sizes mainly concentrated in 50~200 nm at the heating rate of 5 °C/s during annealing. The number of particles under 50nm increased gradually and the number of precipitates between 50~400 nm reduced significantly when the heating rate was increased to 50~300 °C/s. The results indicated that the rapid heating rate could refine the size of precipitates and decrease the number of particles above 50nm.

To develop a multiplex allele-specific PCR (AS-PCR) assay with three-color fluorescence labeling for mitochondrial DNA (mtDNA) SNP typing.Based on the principle of AS-PCR, the primer sets were designed for 20 SNP located on the coding region of mtDNA and divided into 2 groups labeled with FAM and HEX fluorescence, respectively. A primer set included two forward (reverse) allelic specific primers with different sizes and a generic reverse (forward) primer. Blood samples from 200 unrelated individuals were analyzed by AS-PCR and capillary electrophoresis. Three random samples at least for each SNP site were examined and verified by direct sequencing. The haplotype frequency was investigated.Distinct electropherograms of 200 blood samples were obtained successfully. The typing results of direct sequencing were identical to those obtained from AS-PCR. The minimum detectable DNA concentration was 0.2 pg under the system of 10 microL. The sensitivity of the DNA concentrations ranged from 0.5 to 5 pg. The 200 individuals were assigned into 15 haplotype, and the haplotype diversity was 0.906 0.AS-PCR is a simple, rapid and efficient method for mtDNA SNP typing, and can be applied to forensic practice.

Corynebacterium crenatum MT, a mutant from C. crenatum AS 1.542 with a lethal argR gene, exhibits high arginine production. To confirm the effect of ArgR on arginine biosynthesis in C. crenatum, an intact argR gene from wild-type AS 1.542 was introduced into C. crenatum MT, resulting in C. crenatum MT. sp, and the changes of transcriptional levels of the arginine biosynthetic genes and arginine production were compared between the mutant strain and the recombinant strain.Quantitative real-time polymerase chain reaction was employed to analyze the changes of the related genes at the transcriptional level, electrophoretic mobility shift assays were used to determine ArgR binding with the argCJBDF, argGH, and carAB promoter regions, and arginine production was determined with an automated amino acid analyzer.Arginine production assays showed a 69.9% reduction in arginine from 9.01 ± 0.22 mg/mL in C. crenatum MT to 2.71 ± 0.13 mg/mL (P0.05) in C. crenatum MT. sp. The argC, argB, argD, argF, argJ, argG, and carA genes were down-regulated significantly in C. crenatum MT. sp compared with those in its parental C. crenatum MT strain. The electrophoretic mobility shift assays showed that the promoter regions were directly bound to the ArgR protein.The arginine biosynthetic genes in C. crenatum are clearly controlled by the negative regulator ArgR, and intact ArgR in C. crenatum MT results in a significant descrease in arginine production.