Swedish Defence Research Agency

About: Swedish Defence Research Agency is a government organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Radar & Laser. The organization has 1413 authors who have published 2731 publications receiving 56083 citations. The organization is also known as: Totalförsvarets forskningsinstitut.

Solvent-Assisted Trypsin Digestion of Ricin for Forensic Identification by LC-ESI MS/MS

Abstract: The castor bean plant (Ricinus communis) is used in large quantities for oil production and is also a common ornamental garden plant. However, the beans contain 1-3% of the highly toxic protein ricin, a type II ribosome-inactivating protein that is covered by the Chemical Weapons Convention, and there have been a number of reports concerning the use, or alleged use, of the toxin in terrorist and criminal activities. In the study reported here, we investigated the potential utility of organic solvent-assisted trypsin digestion of crude extracts containing the closely related toxins ricin or abrin to prepare samples for peptide analysis by liquid chromatography combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry. Diagnostic tryptic fragments of the toxins were detected and unambiguously identified by this procedure. The sample preparation protocol substantially reduces the sample preparation time, from overnight to an hour, and thus greatly reduces the total time required for analyses, to less than 2 h. Furthermore, the reported procedure leaves the disulfide bonds in the protein intact. This is highly relevant in the context of the Chemical Weapons Convention, since the disulfide bond connecting the two chains of ricin indicates the presence of an intact toxin and provides additional forensic evidence for the analytical results.

Design and synthesis of multifunctional thiacalixarenes and related metal derivatives for the preparation of sol–gel hybrid materials with non-linear optical properties

Abstract: Thiacalixarenes bearing phenylazo or ethynylic groups on the lower rims were prepared and fully characterized. The functional groups were chosen for their ability to increase the electron delocalisation over the molecule and to form metal complexes. The formation of complexes between phenylazothiacalixarenes and metal salts (Zn2+, Ag+…), and the synthesis of platinum acetylides from ethynylthiacalixarenes were investigated. Preliminary studies on optical limiting properties for both ligands and complexes is reported. Clamping levels of ∼4 µJ at 532 nm, were observed for both tetra(pentylphenylethynyl)tetrapropoxythiacalix[4]arene (150 mM in THF, 99% transmission) and the platinum complex (30 mM in THF, 83% transmission). A second functionalisation (upper rims) with metal alkoxide groups has also been investigated in order to prepare hybrid materials incorporating the optically active molecule. The same macrocycle core was thus bifunctionalised, and used for its optical properties on one side and as a precursor of an inorganic network for hybrid materials on the other.

Quantifying Success Factors for IT Projects: An Expert-Based Bayesian Model

Abstract: Large investments are made annually to develop and maintain IT systems. Successful outcome of IT projects is therefore crucial for the economy. Yet, many IT projects fail completely or are delayed or over budget, or they end up with less functionality than planned. This article describes a Bayesian decision-support model. The model is based on expert elicited data from 51 experts. Using this model, the effect management decisions have upon projects can be estimated beforehand, thus providing decision support for the improvement of IT project performance.

Understanding scramjet combustion using LES of the HyShot II combustor

Abstract: Detailed understanding of the physical processes occurring in the combustor of a scramjet engine is crucial for enabling this technology and is considered the most promising for hypersonic flight. Laboratory, ground testing, and flight-testing experiments, together with simulations, comprise the tools available to fill the current gap in scramjet combustor knowledge. Here, a computational study has been carried out for the HyShot II scramjet combustor using Large Eddy Simulation (LES) models together with one skeletal and one comprehensive reaction mechanism. Based on a survey of the experimental data available for the HyShot II combustor, we focus on the High Enthalpy Shock Tunnel Gottingen (HEG) operating condition XIII, emulating flight conditions at 28 km altitude. To account for slight experimental run-to-run variations, two simulations are performed at different equivalence ratios. The LES are found to capture the experimental wall-pressure and heat-flux data well compared to the measurement data, with marginal influence of the reaction mechanism. The LES results are subsequently used to analyze the flow, mixing, and combustion processes involved. The tools employed include conventional, as well as recently developed methods, such as the Takeno flame index and Chemical Explosive Mode Analysis. These methods give a concise description of the interactions between flow, fuel–air mixing, and combustion, and it is discovered that supersonic combustion is a combination of auto-ignition and non-premixed flame regions and self-igniting fronts. Furthermore, ignition is enabled by shocks, and the supersonic flame is very different in nature to subsonic turbulent flames.

Discrimination of Human Pathogenic Subspecies of Francisella tularensis by Using Restriction Fragment Length Polymorphism

Abstract: We describe the use of two insertion sequence elements (ISFtu1 and ISFtu2) in Francisella tularensis to type strains by restriction fragment length polymorphism (RFLP). The RFLP profiles of 17 epidemiologically unrelated isolates were determined and compared. Our results showed that RFLP profiles can be used to assign F. tularensis strains into five main groups corresponding to strains of F. tularensis subsp. tularensis, F. tularensis strain ATCC 6223, strains of F. tularensis subsp. holarctica, strains of F. tularensis subsp. holarctica from Japan, and F. tularensis subsp. mediaasiatica. The results confirm the genetic identities of these subspecies and also support the suggestion that strains of F. tularensis subsp. holarctica from Japan should be considered members of a separate biovar. These findings should support future studies to determine the genetic differences between strains of F. tularensis at the whole-genome level.