Elastomeric seal stress analysis using photoelastic experimental hybrid method.

Stress freezing is an important and powerful procedure in 3-dimensional experimental stress analysis using photoelasticity. The application of the stress freezing technique to extract stress components from loaded engineering structures has, however, declined over the years even though its principles are well established. This is attributed to huge costs arising from energy consumption during the process. In addition, significant time is needed to generate the desired information from isoclinic and isochromatic fringes. To overcome the limitations of stress freezing in photoelasticity and transform it into an economical device for stress analysis in an engineering environment, a new stress freezing cycle that lasts 5 h is proposed. The proposed technique is used in several applications of elastomeric seals with different cross-sectional profiles to assess their suitability. It was found that reducing the cycle time can lead to huge energy savings without compromising the quality of the fringes. Moreover, the use of isochromatic only to extract stress components leads to a shorter processing time to achieve desirable information since the process of obtaining isoclinic data is involving. In this paper, results of stress analysis from stress-frozen elastomeric seals with various cross-sections using the new stress freezing cycle are presented.

Complete Chloroplast Genome Sequences and Comparative Analysis of Chenopodium quinoa and C. album.

The Chenopodium genus comprises ~150 species, including Chenopodium quinoa and Chenopodium album, two important crops with high nutritional value. To elucidate the phylogenetic relationship between the two species, the complete chloroplast (cp) genomes of these species were obtained by next generation sequencing. We performed comparative analysis of the sequences and, using InDel markers, inferred phylogeny and genetic diversity of the Chenopodium genus. The cp genome is 152,099 bp (C. quinoa) and 152,167 bp (C. album) long. In total, 119 genes (78 protein-coding, 37 tRNA, and 4 rRNA) were identified. We found 14 (C. quinoa) and 15 (C. album) tandem repeats (TRs); 14 TRs were present in both species and C. album and C. quinoa each had one species-specific TR. The trnI-GAU intron sequences contained one (C. quinoa) or two (C. album) copies of TRs (66 bp); the InDel marker was designed based on the copy number variation in TRs. Using the InDel markers, we detected this variation in the TR copy number in four species, Chenopodium hybridum, Chenopodium pumilio, Chenopodium ficifolium, and Chenopodium koraiense, but not in Chenopodium glaucum. A comparison of coding and non-coding regions between C. quinoa and C. album revealed divergent sites. Nucleotide diversity >0.025 was found in 17 regions-14 were located in the large single copy region (LSC), one in the inverted repeats, and two in the small single copy region (SSC). A phylogenetic analysis based on 59 protein-coding genes from 25 taxa resolved Chenopodioideae monophyletic and sister to Betoideae. The complete plastid genome sequences and molecular markers based on divergence hotspot regions in the two Chenopodium taxa will help to resolve the phylogenetic relationships of Chenopodium.