University of Fribourg

About: University of Fribourg is a education organization based out in Fribourg, Freiburg, Switzerland. It is known for research contribution in the topics: Population & Glacier. The organization has 6040 authors who have published 14975 publications receiving 542500 citations. The organization is also known as: UNIFR & Universität Freiburg.

The Epidermis-Specific Extracellular BODYGUARD Controls Cuticle Development and Morphogenesis in Arabidopsis

Abstract: The outermost epidermal cell wall is specialized to withstand pathogens and natural stresses, and lipid-based cuticular polymers are the major barrier against incursions. The Arabidopsis thaliana mutant bodyguard (bdg), which exhibits defects characteristic of the loss of cuticle structure not attributable to a lack of typical cutin monomers, unexpectedly accumulates significantly more cell wall‐bound lipids and epicuticular waxes than wild-type plants. Pleiotropic effects of the bdg mutation on growth, viability, and cell differentiation are also observed. BDG encodes a member of the a/b-hydrolase fold protein superfamilyandisexpressedexclusivelyinepidermalcells.UsingStrep-tagepitope-taggedBDGformutantcomplementation and immunolocalization, we show that BDG is a polarly localized protein that accumulates in the outermost cell wall in the epidermis.Withregardtotheappearance andstructureofthecuticle, thephenotype conferredbybdgisreminiscent ofthatof transgenic Arabidopsis plants that express an extracellular fungal cutinase, suggesting that bdg may be incapable of completing the polymerization of carboxylic esters in the cuticular layer of the cell wall or the cuticle proper. We propose that BDGcodesforanextracellularsynthaseresponsiblefortheformationofcuticle.ThealternativehypothesisproposesthatBDG controls the proliferation/differentiation status of the epidermis via an unknown mechanism.

Effect of graphene oxide doping on superconducting properties of bulk MgB2

Abstract: In the present paper we report the effect of graphene oxide (GO) doping on the structural and superconducting properties of MgB2. Bulk polycrystalline samples have been synthesized via a solid state reaction route with compositions MgB2?+?x?wt% of GO (x?=?0, 1, 2, 3, 5, 7 and 10) by sintering at ?850?? C in a reducing atmosphere of Ar/H2 (9:1). The x-ray diffraction results confirm the formation of the MgB2 phase in all samples, together with traces of a MgO impurity phase. The XRD data results also show substitution of carbon for boron, but in the present case the actual amount of carbon substituting for boron is very small as compared to other carbon sources. A substantial improvement in the critical current density, Jc(H), has been observed in the entire magnetic field range (0?8?T) for samples x?=?1, 2 and 3 as compared to the undoped sample. In addition to Jc(H), marginal improvements in the upper critical field (Hc2) and the irreversibility field (Hirr) have been observed for the doped samples x?=?1, 2 and 3 with respect to pristine MgB2. Furthermore, a curious result of the present investigation is that there is no change in the superconducting transition temperature (Tc) up to a doping level of 10?wt%. The possible mechanisms of flux pinning and correlations between the observed superconducting properties and structural characteristics of the samples have been described and discussed in this paper.