40 research outputs found
Development of Genome-wide Simple Sequence Repeat Markers Using Whole-genome Shotgun Sequences of Sorghum (Sorghum bicolor (L.) Moench)
Simple sequence repeat (SSR) markers with a high degree of polymorphism contribute to the molecular dissection of agriculturally important traits in sorghum (Sorghum bicolor (L.) Moench). We designed 5599 non-redundant SSR markers, including regions flanking the SSRs, in whole-genome shotgun sequences of sorghum line ATx623. (AT/TA)n repeats constituted 26.1% of all SSRs, followed by (AG/TC)n at 20.5%, (AC/TG)n at 13.7% and (CG/GC)n at 11.8%. The chromosomal locations of 5012 SSR markers were determined by comparing the locations identified by means of electronic PCR with the predicted positions of 34 008 gene loci. Most SSR markers had a similar distribution to the gene loci. Among 970 markers validated by fragment analysis, 67.8% (658 of 970) markers successfully provided PCR amplification in sorghum line BTx623, with a mean polymorphism rate of 45.1% (297 of 658) for all SSR loci in combinations of 11 sorghum lines and one sudangrass (Sorghum sudanense (Piper) Stapf) line. The product of 5012 and 0.678 suggests that ∼3400 SSR markers could be used to detect SSR polymorphisms and that more than 1500 (45.1% of 3400) markers could reveal SSR polymorphisms in combinations of Sorghum lines
Crystallization of Ti33Cu67 metallic glass under high-current density electrical pulses
We have studied the phase and structure evolution of the Ti33Cu67 amorphous alloy subjected to electrical pulses of high current density. By varying the pulse parameters, different stages of crystallization could be observed in the samples. Partial polymorphic nanocrystallization resulting in the formation of 5- to 8-nm crystallites of the TiCu2 intermetallic in the residual amorphous matrix occurred when the maximum current density reached 9.7·108 A m-2 and the pulse duration was 140 μs, though the calculated temperature increase due to Joule heating was not enough to reach the crystallization temperature of the alloy. Samples subjected to higher current densities and higher values of the evolved Joule heat per unit mass fully crystallized and contained the Ti2Cu3 and TiCu3 phases. A common feature of the crystallized ribbons was their non-uniform microstructure with regions that experienced local melting and rapid solidification
Uncovering of major genetic factors generating naturally occurring variation in heading date among Asian rice cultivars
To dissect the genetic factors controlling naturally occurring variation of heading date in Asian rice cultivars, we performed QTL analyses using F2 populations derived from crosses between a japonica cultivar, Koshihikari, and each of 12 cultivars originating from various regions in Asia. These 12 diverse cultivars varied in heading date under natural field conditions in Tsukuba, Japan. Transgressive segregation was observed in 10 F2 combinations. QTL analyses using multiple crosses revealed a comprehensive series of loci involved in natural variation in flowering time. One to four QTLs were detected in each cross combination, and some QTLs were shared among combinations. The chromosomal locations of these QTLs corresponded well with those detected in other studies. The allelic effects of the QTLs varied among the cross combinations. Sequence analysis of several previously cloned genes controlling heading date, including Hd1, Hd3a, Hd6, RFT1, and Ghd7, identified several functional polymorphisms, indicating that allelic variation at these loci probably contributes to variation in heading date. Taken together, the QTL and sequencing results indicate that a large portion of the phenotypic variation in heading date in Asian rice cultivars could be generated by combinations of different alleles (possibly both loss- and gain-of-function) of the QTLs detected in this study
Joule-heating Effects In the Amorphous Fe40ni40b20 Alloy
The effects of Joule heating on the amorphous Fe40Ni40B20 alloy are investigated by measuring the time behavior of the electrical resistance of ribbon strips during such a treatment. The structural transformations occurring in subsequent stages of the process are studied by means of x-ray-diffraction, differential-scanning-calorimetry, and magnetic-permeability measurements. A continuous evolution from a fully amorphous to a fully crystalline structure may be followed. The crystallization mechanisms observed in Joule-heated samples differ from the ones occurring under conventional heating conditions. The electrical resistance displays a bump in the course of Joule heating. A quantitative model relating such a bump to the extra heat released to the sample by fast crystallization is proposed and discussed
Long-Range Diffusion of Hydrogen in Amorphous Cu50Ti50
The hydrogen Gorsky effects (HGE) measurements were carried out in amorphous Cu50Ti50, for which the data for the hydrogen Snoek peak (HSP) have been compiled. In the hydrogen concentration, CH, range below 1 at.%, the hydrogen diffusion process changes over from the short circuit mode to the detrapping mode with increasing CH and (λ)2 is much smaller than (trλ)2, where λ is the strain tensor around a hydrogen atom. For CH>1 at.%, the hydrogen diffusion proceeds by the detrapping mode. The whole hydrogen atoms contribute to the HGE although only hydrogen atoms sitting on the sites with G being nearly equal to µ contribute to the HSP, where G is the site energy and µ the chemical potential of hydrogen atoms. The results are expected as a dispersion in G is much larger than thermal energies and the nearest neighbor blocking for hydrogen occupation is the case. (λ)2 is much larger than , suggesting that one or two of (trλ)2, λ1,λ2 and λ3 is (are) negative for CH>1 at.%
Elasticity Study on Ag nm-Films
Young's modulus Ef of polycrystalline Ag nm-films deposited on hydrogen-terminated Si was measured in the film thickness d range between 6 and 50 nm by means of the vibrating reed method. Ef observed for d above about 20 nm is slightly higher than the upper bound of Young's modulus expected for polycrystalline Ag bulk-films. On the other hand, with decreasing d, Ef decreases beyond the lower bound of Young's modulus expected for polycrystalline Ag bulk-films. The plausible models to explain these results are discussed