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 & Synthetic aperture radar. The organization has 1413 authors who have published 2731 publications receiving 56083 citations. The organization is also known as: Totalförsvarets forskningsinstitut.

Forensic Identification of Neat Ricin and of Ricin from Crude Castor Bean Extracts by Mass Spectrometry

Abstract: The protein toxin ricin, which originates from the seeds of Ricinus communis plants, has been the subject of increased interest, due to its potential terrorist use. Exceptionally, this toxin is also subject to the Chemical Weapons Convention. In this paper, it is shown that mass spectrometry can be used to unambiguously verify the presence of ricin in crude toxin preparations. It is demonstrated that MALDI MS can be used for screening, either by direct analysis or by trypsin digestion and peptide mapping. Purified ricin from several varieties of R. communis was characterized by LC-ES MS(/MS). A crude ricin preparation from a single bean was similarly characterized. An LC method was set up with product ion MS/MS detection of selected marker peptides specific for ricin: T5, T7, T11, T12, and T13 from the A-chain and T3, T5, T14, T19, and T20 from the B-chain. This method was then used to unambiguously identify ricin in a crude preparation of ricin. The MALDI MS molecular weight analysis and the marker peptides LC-ES MS/MS analysis give a forensic level of identification of ricin when combined with activity testing.

Mapping of immunoreactive antigens of Francisella tularensis live vaccine strain

Abstract: Francisella tularensis subsp. holarctica is the common causal agent of tularemia in Europe. Besides clinical signs, the diagnosis of the disease mostly depends on serological tests. To date, there is a lack of information about the F. tularensis antigens that induce antibody response. Therefore, we have started comprehensive mapping of immunoreactive antigens using the attenuated live vaccine strain of F. tularensis LVS originating from the European virulent strain. For this purpose, the immunoreactivity of sera collected from patients suffering from tularemia, together with the control sera of patients with Lyme disease and healthy blood donors, were examined by means of one-dimensional and two-dimensional immunoblotting. Furthermore, whole cell bacterial lysates, isolated integral membrane proteins and basic proteins were exploited as antigens. By this approach more than 80 different immunorelevant antigens were detected. Most of them came from whole cell bacterial lysate and integral membrane proteins. Conversely, only a negligible reaction was found in the case of basic proteins. Forty-five spots were further selected for mass spectrometric analyses and 22 of them were annotated. Among the spots that provided characteristic reactions with sera from patients with tularemia, 60 kDa and 10 kDa chaperonins that occurred in several charge and mass variants, predominated.

The electronic structure and reflectivity of PEDOT:PSS from density functional theory

Abstract: The geometric and electronic structure of condensed phase organic conducting polymer PEDOT:PSS blends has been investigated by periodic density functional theory (DFT) calculations with a generalized-gradient approximation (GGA) functional, and a plane wave basis set. The influence of the degree of doping of the PEDOT polymer on structural and optical parameters such as the reflectivity, absorbance, conductivity, dielectric function, refractive index and the energy-loss function is studied. A flip from the benzoid to the quinoid structure is observed in the calculations when the neutral PEDOT is doped by negatively charged PSS. Also the optical properties are affected by the doping. In particular, the reflectivity was found to be very sensitive to the degree of doping, where higher doping implies higher reflectivity. The reflectivity is highly anisotropic, with the dominant contribution stemming from the direction parallel to the PEDOT polymer chain.