Synthesis of new cyclic and acyclic biologically relevant amino acid derivatives

The discovery of non-proteinogenic amino acids among natural products has significantly increased interest in this class of compounds as they may possess interesting biological activity and could also serve as valuable building blocks in the synthesis of new classes of bioactive compounds as well as for the synthesis and design of peptides. Some natural non-proteinogenic amino acids were proposed as neurotoxic compounds which play a role in neurodegenerative diseases. The misincorporation of some non-proteinogenic amino acids into proteins in place of canonical amino acids causes toxic effect and has been implicated in the pathophysiology of a wide range of diseases, including amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease. In that respect, the synthesis of new derivatives of non-proteinogenic α- and β-amino acids, including acyclic and cyclic scaffolds, was the subject of the present research

Spin current generation from Coulomb-Rashba interaction in semiconductor bilayers

Electrons in double-layer semiconductor heterostructures experience a special type of spin-orbit interaction which arises in each layer from the perpendicular component of the Coulomb electric field created by electron density fluctuations in the other layer. We show that this interaction, acting in combination with the usual spin-orbit interaction, can generate a spin current in one layer when a charge current is driven in the other. This effect is symmetry-wise distinct from the spin Hall drag. The spin current is not, in general, perpendicular to the drive current.Comment: 4 pages, 2 figure

Current molecular understanding of Axenfeld-Rieger syndrome.

Axenfeld-Rieger syndrome (ARS) is a rare autosomal dominant inherited disorder affecting the development of the eyes, teeth and abdomen. The syndrome is characterised by complete penetrance but variable expressivity. The ocular component of the ARS phenotype has acquired most clinical attention and has been dissected into a spectrum of developmental eye disorders, of which open-angle glaucoma represents the main challenge in terms of treatment. Mutations in several chromosomal loci have been implicated in ARS, including PITX2, FOXC1 and PAX6. Full-spectrum ARS is caused primarily by mutations in the PITX2 gene. The homeobox transcription factor PITX2 is produced as at least four different transcriptional and splicing isoforms, with different biological properties. Intriguingly, PITX2 is also involved in left-right polarity determination, although asymmetry defects are not a feature of ARS. In experimental animal models and in cell culture experiments using PITX2, abundant evidence indicates that a narrow window of expression level of this gene is vital for its correct function

Phase Composition and Defect Substructure of Strengthening Layer Surfaced on Low Alloyed Steel

The microstructure and microhardness distribution in surface of low carbon Hardox 450 steel coated with alloyed powder wires of different chemical compositions are studied. It is shown that the microhardness of 6-8 mm thickness surfaced layer exceeds that of base metal by more than 2 times. The increased mechanical properties of surfaced layer are caused by the submicro and nanoscale dispersed martensite, containing the niobium carbides Nb2C, NbC and iron borides Fe2B. In the bulk plates a dislocation substructure of the net-like type with scalar islocation density of 10^11 cm^-2 is observed. The layer surfaced with the wire containing B possesses the highest hardness. The possible mechanisms of niobium and boron carbides formation in surfacing are discusse