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21.
In the past decade, trees and shrubs in the Western Balkans region have been damaged by canker and die‐back disease caused by Botryosphaeriaceae species. These pathogens include Neofusicoccum parvum and Diplodia sapinea. In this study, we determine genetic diversity and structure between populations of N. parvum and D. sapinea from Serbia and Montenegro (Western Balkans) using DNA sequence data of the internal transcribed spacer rDNA, translation elongation factor 1‐alpha, β‐tubulin‐2 and microsatellite markers. The relationship of both pathogens was compared for populations from the Continental (CR) and Mediterranean (MR) regions and for isolates of D. sapinea from Cedrus spp. and Pinus spp. Neofusicoccum parvum and D. sapinea were shown to have a low gene and genotypic diversity across the regions and hosts. All genotypes of D. sapinea found on Pinus spp. were also present on Cedrus spp. The CR and MR populations of both species were found to be only slightly separated from one another by a geographical barrier. Low genetic diversity and dominance of N. parvum and D. sapinea on non‐native trees suggests that these species have most likely been introduced into Western Balkans, possibly through the movement of infected plants. 相似文献
22.
Breaking strength is one of the most important mechanical property of a yarn as it is the main parameter for quality control.
This property depends on many different factors namely, raw material factors, process variables and machine parameters. Since,
there is a high degree of interaction between yarn properties and influencing factors therefore, optimal processing conditions
can not be determined easily. This article proposes prediction approach for the determination of the breaking strength of
the yarn using gene expression programming (GEP) and optimization technique using MATLAB software. A nonlinear mathematical
function was derived on the basis of draw frame variables that were distance between back and middle rolls, delivery speed
and break draft by GEP. Afterward, optimal conditions were found in such a way that breaking strength to be maximized. Study
showed that, optimal processing parameters including distance between back and middle rolls, break draft and delivery speed
were respectively, 10.70 mm, 1.90 and 541.51 m/min (687.95 or 721.32 based on the optimization procedure). 相似文献