Defence Science and Technology Laboratory

About: Defence Science and Technology Laboratory is a government organization based out in Salisbury, United Kingdom. It is known for research contribution in the topics: Burkholderia pseudomallei & Francisella tularensis. The organization has 926 authors who have published 1242 publications receiving 30091 citations. The organization is also known as: Dstl & [dstl].

Genetic Relationships and Evolution of Genotypes of Yellow Fever Virus and Other Members of the Yellow Fever Virus Group within the Flavivirus Genus Based on the 3′ Noncoding Region

Abstract: Genetic relationships among flaviviruses within the yellow fever (YF) virus genetic group were investigated by comparing nucleotide sequences of the 3' noncoding region (3'NCR). Size heterogeneity was observed between members and even among strains of the same viral species. Size variation between YF strains was due to duplications and/or deletions of repeated nucleotide sequence elements (RYF). West African genotypes had three copies of the RYF (RYF1, RYF2, and RYF3); the Angola and the East and Central African genotypes had two copies (RYF1 and RYF3); and South American genotypes had only a single copy (RYF3). Nucleotide sequence analyses suggest a deletion within the 3'NCR of South American genotypes, including RYF1 and RYF2. Based on studies with the French neurotropic vaccine strain, passage of a YF virus strain in cell culture can result in deletion of RYF1 and RYF2. Taken together, these observations suggest that South American genotypes of YF virus evolved from West African genotypes and that the South American genotypes lost RYF1 and RYF2, possibly in a single event. Repeated sequence elements were found within the 3'NCR of other members of the YF virus genetic group, suggesting that it is probably characteristic for members of the YF virus genetic group. A core sequence of 15 nucleotides, containing two stem-loops, was found within the 3'NCR of all members of the YF genetic group and may represent the progenitor repeat sequence. Secondary structure predictions of the 3'NCR showed very similar structures for viruses that were closely related phylogenetically.

The Preparation of Auxetic Foams by Three-Dimensional Printing and Their Characteristics

Abstract: Repeatable auxetic foams are produced using three-dimensional printing technologies. This methodology is applied here for the first time to produce playable polymeric auxetic foams with an idealized re-entrant cellular structure. During uniaxial tensile stress, the foams show negative Poisson's ratios as low as ?1.18. The experimental Poisson's ratios of the auxetic foams are compared against the data predicted by a three-dimensional mathematical model