Littérature scientifique sur le sujet « Structrural features »

The obtuse triangular defects would result in higher leakage currents and the preferential gate oxide breakdown of SiC devices. The formation and structural features of obtuse triangular defects on the 4° off 4H-SiC epilayers were investigated by confocal microscope and photoluminescence image. Two structrures of obtuse triangular defects were found. By optimizing the growth process, obtuse triangular defect free epitaxial layers were abtained on SiC substrate with serveral stacking fault. The number of triangular SFs defects was less than 0.5/cm2.

Expanding the investigations related to land price analysis, this study demonstrates the territorial aspects of the issue through the example of Bács-Kiskun county enriching the methodology of spatial structure researches. The applied correlation analysis confirmed our assumption that scarcely more than a decade after the change of ownership relations, great differences can be detected among land prices, which reflect the main features of the county’s spatial structure. The land price map of Bács-Kiskun County demonstrates the main features of the spatial structrure and the characteristics of the centre-periphery relationships at municipal level. High land prices are typical in the areas which are rich in innovations and can be characterized with denser texture. Getting farther from them, the land prices become lower. Their temporal changes are also consistent with the interactions taking place in the spatial structure.

In this article is considered nature process of formation service centers of local level in the environment of the largest city. By the example of Samara city are revealed the local centers and areas of their functioning, considered functional structure, features of formation, typology of the local centers.

Human profiin-1 is a novel protein associated with a recently discovered form of familial amyotrophic lateral sclerosis. This urges the characterization of possible conformational states, different from the fully folded state, potentially able to initiate self-assembly. Under native conditions, profiin-1 is monomeric and possesses a well-defied secondary and tertiary structure. When incubated at low pH or with high urea concentrations, profiin-1 remains monomeric but populates unfolded states exhibiting larger hydrodynamic radius and disordered structure, as assessed by dynamic light scattering, far-UV circular dichroism and intrinsic florescence. Refolding from the urea unfolded state was studied at equilibrium and in real-time using a stopped-flow apparatus. The results obtained with intrinsic florescence and circular dichroism indicate a single phase without significant changes of the corresponding signals before the major refolding transition. However, such a transition is preceded by a burst phase with an observed increase of ANS florescence, which indicates the conversion into a transiently populated collapsed state possessing solvent exposed hydrophobic clusters. Kinetic analysis reveals that such state has a conformational stability comparable to that of the fully unfolded state. To our knowledge, profiin-1 is the first example of an amyloid-related protein where folding occurs in the absence of thermodynamically stable partially folded states.The PFN1 gene, coding for profilin-1, has recently been associated with familial amyotrophic lateral sclerosis (fALS), as five mutations, namely C71G, M114T, G118V, A20T and T109M have been found in patients with familial forms of the disease and others, E117G and Q139L, has been proposed to be a moderate risk factor for disease onset. In this second part of the thesis we have purified the four profilin-1 variants along with the wild type protein. The resulting aggregates appear to be fibrillar, to have a weak binding to ThT, and to possess a significant amount of intermolecular β-sheet structure. Using ThT fluorescence assays, far-UV circular dichroism, and dynamic light scattering, we found that all variants have an aggregation propensity higher than that of the wild-type counterpart. In particular, the C71G mutation was found to induce the most dramatic change in aggregation. Such a propensity was found not to strictly correlate with the conformational stability in this group of profilin-1 variants, determined using both urea-induced denaturation at equilibrium and folding/unfolding kinetics. However, it correlated with structural changes of the folded states, as monitored with far-UV circular dichroism, intrinsic fluorescence spectroscopy, ANS binding, acrylamide quenching, and dynamic light scattering. Overall, the results suggest that all mutations increase the tendency of profilin-1 to aggregate and that such aggregation behavior is largely determined by the mutation-induced structural changes occurring in the folded state of the protein.