Jožef Stefan Institute

About: Jožef Stefan Institute is a facility organization based out in Ljubljana, Slovenia. It is known for research contribution in the topics: Liquid crystal & Dielectric. The organization has 3828 authors who have published 12614 publications receiving 291025 citations.

The CC domain structure from the wheat stem rust resistance protein Sr33 challenges paradigms for dimerization in plant NLR proteins.

Abstract: Plants use intracellular immunity receptors, known as nucleotide-binding oligomerization domain-like receptors (NLRs), to recognize specific pathogen effector proteins and induce immune responses. These proteins provide resistance to many of the world’s most destructive plant pathogens, yet we have a limited understanding of the molecular mechanisms that lead to defense signaling. We examined the wheat NLR protein, Sr33, which is responsible for strain-specific resistance to the wheat stem rust pathogen, Puccinia graminis f. sp. tritici. We present the solution structure of a coiled-coil (CC) fragment from Sr33, which adopts a four-helix bundle conformation. Unexpectedly, this structure differs from the published dimeric crystal structure of the equivalent region from the orthologous barley powdery mildew resistance protein, MLA10, but is similar to the structure of the distantly related potato NLR protein, Rx. We demonstrate that these regions are, in fact, largely monomeric and adopt similar folds in solution in all three proteins, suggesting that the CC domains from plant NLRs adopt a conserved fold. However, larger C-terminal fragments of Sr33 and MLA10 can self-associate both in vitro and in planta, and this self-association correlates with their cell death signaling activity. The minimal region of the CC domain required for both cell death signaling and self-association extends to amino acid 142, thus including 22 residues absent from previous biochemical and structural protein studies. These data suggest that self-association of the minimal CC domain is necessary for signaling but is likely to involve a different structural basis than previously suggested by the MLA10 crystallographic dimer.

Photoelectrochemical activity of as-grown, α-Fe2O3 nanowire array electrodes for water splitting

Abstract: Undoped hematite nanowire arrays grown using plasma oxidation of iron foils show significant photoactivity (?0.38?mA?cm?2 at 1.5?V versus reversible hydrogen electrode in 1?M KOH). In contrast, thermally oxidized nanowire arrays grown on iron exhibit no photoactivity due to the formation of a thick (>7??m?Fe1?xO) interfacial layer. An atmospheric plasma oxidation process required only a few minutes to synthesize hematite nanowire arrays with a 1?5??m interfacial layer of magnetite between the nanowire arrays and the iron substrate. An amorphous oxide surface layer on hematite nanowires, if present, is shown to decrease the resulting photoactivity of as-synthesized, plasma grown nanowire arrays. The photocurrent onset potential is improved after removing the amorphous surface on the nanowires using an acid etch. A two-step method involving high temperature nucleation followed by growth at low temperature is shown to produce a highly dense and uniform coverage of nanowire arrays.

Preparation and properties of water-based magnetic fluids.

Abstract: Stable suspensions of superparamagnetic iron oxide nanoparticles in water (water-based ferrofluids) were prepared using citric acid (CA) as a surfactant. The influences of different factors on the amount of nanoparticles in a stable suspension were systematically studied. These factors, including the temperature, the pH value and the concentration of CA applied during the adsorption of the CA onto the nanoparticles and during their suspension in water, were evaluated. The highest content of nanoparticles in a stable suspension was obtained when the CA was absorbed at pH values of around 5.2, where two carboxyl groups are dissociated, and when the nanoparticles were suspended at a pH of around 10, where all three carboxyl groups of the CA are in a dissociated state.

Status of the Belle silicon vertex detector

Abstract: The old silicon vertex detector (SVD1) of the Belle detector, operating at the high-luminosity asymmetric energy e+e− collider KEKB, was replaced by an upgraded version (SVD2) in 2003. The new detector has modified geometry and redesigned readout electronics, providing a larger polar angle acceptance, better vertex resolution, improved radiation hardness and reduced dead time. The operation of the detector started successfully in October 2003. The basic concepts of the SVD2 design as well as its performance after 10 months of data taking are described in this paper.