Insight on the silver catalyst distribution during silicon nanowire array formation: an X-ray reflectivity study.

Although metal-catalysts are commonly used to create nanoscale materials at surfaces, little is quantitatively known or understood about the depth distribution profile of the catalyst during the growth process. Using X-ray reflectivity, we report the first quantitative investigation, with nanoscale resolution, of the Ag metal-catalyst depth distribution profile during metal-assisted chemical etch (MACE) growth of Si nanowire (SiNW) arrays on Si(100). Given the very low optical reflectivity of these nanowire arrays, specular reflection from these materials in the X-ray region is extremely challenging to measure because it probes interfaces on the nanoscale.

Mott insulator-to-metal transition in yttrium-doped CaIrO₃.

We report on the study of insulator-to-metal transition in post-perovskite compound CaIrO3. It is discovered that a gradual chemical substitution of calcium by yttrium leads to the onset of strong metallic behavior in this compound. This observation is in stark contrast to BaIrO3, which preserves its Mott insulating behavior despite excess of the charge carriers due to yttrium doping.

[Phytotherapeutic aspects of diseases of the circulatory system. 4. Chitin and chitosan].

Chitin and chitosan are nitrogenous polysaccharides. The structure of the chitin molecule is similar to that of cellulose but it is composed of the units of 2-acetylamino-2-deoxy-D-glucopyranose bound (1 --> 4) by a glycosidic bond. In contrast to chitin, chitosan amino groups are not mostly acetylated.