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Tetraploid cotton is one of the most extensively cultivated species. Two tetraploid species, Gossypium hirsutum L. and G. barbadense L., dominate the world's cotton production. To better understand the genetic basis of cotton fibre traits for the improvement of fibre quality, a genetic linkage map of tetraploid cotton was constructed using sequence-related amplified polymorphisms (SRAPs), simple sequence repeats (SSRs) and random amplified polymorphic DNAs (RAPDs). A total of 238 SRAP primer combinations, 368 SSR primer pairs and 600 RAPD primers were used to screen polymorphisms between G. hirsutum cv. Handan208 and G. barbadense cv. Pima90 which revealed 749 polymorphic loci in total (205 SSRs, 107 RAPDs and 437 SRAPs). Sixty-nine F 2 progeny from the interspecific cross of ÔHandan208Õ · ÔPima90Õ were genotyped with the 749 polymorphic markers. A total of 566 loci were assembled into 41 linkage groups with at least three loci in each group. Twenty-eight linkage groups were assigned to corresponding chromosomes by SSR markers with known chromosome locations. The map covered 5141.8 cM with a mean interlocus space of 9.08 cM. A v 2 test for significance of deviations from the expected ratio (1 : 2 : 1 or 3 : 1) identified 135 loci (18.0%) with skewed segregation, most of which had an excess of maternal parental alleles. In total, 13 QTL associated with fibre traits were detected, among which two QTL were for fibre strength, four for fibre length and seven for micronaire value. These QTL were on nine linkage groups explaining 16.18-28.92% of the trait variation. Six QTL were located in the A subgenome, six QTL in the D subgenome and one QTL in an unassigned linkage group. There were three QTL for micronaire value clustered on LG1, which would be very useful for improving this trait by molecular marker-assisted selection.

Deadlegs in oil and gas production systems often encounter hydrate plugs by deposition. Temperature is generally known to be an important variable in hydrate formation, but the effects in deadlegs are not exactly known. This study focuses on the effects of the header temperature on the hydrate deposition in gas-filled vertical deadlegs at constant wall temperature. All experiments are conducted with a methane/ethane gas mixture at constant pressure. The pipe wall temperature is kept constant while considering different header temperatures. The tests show that the header temperature has a significant impact in the hydrate deposit growth rate and distribution in the deadleg. It is also found that the hydrate deposit can, in turn, change the temperature field inside the pipe. The header temperature or the pipe temperature field can be used to estimate the hydrate distribution in the deadleg. Under the right conditions, hydrates can form a restriction in the deadleg and its location is usually close to the boundary of a hydrate-stable region. The location of the restriction can be correlated to the header temperature. At 80 °C, the location is estimated to be 15−18 ID, and at 30 °C, the location is estimated to be 9−12 ID. The results of this study contribute to the understanding of the hydrate deposition mechanism in deadlegs.

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In the oil and gas industry, deadlegspipe sections without through-flowoften pose hydrate control challenges to gas and oil production systems. The hydrate challenges, if not properly managed, can cause severe consequences in terms of safety and cost for oil/gas production. This paper provides an overview of deadlegs in oil and gas production systems with some examples of typical challenges faced in the oil industry. Two different types of vertical deadleg experimental systems have been developed to acquire a better understanding of hydrate risks in gas-dominated deadlegs. These systems offer valuable quantitative information on hydrate deposit, such as thickness, porosity, morphology, growth rate, distribution, temperature profile, and amount of water and/or gas consumed as a factor of time in the deadleg system.