• Closed Access close
• Publications close
• Research software close
• CZ close

The rocks of the crystalline basement of the East European Craton in southern Estonia show effects of partial melting under granulite facies conditions. Zircons extracted from partial melting products (tonalite from the Tapa Zone – 1824 ± 26, tonalite from the South Estonian Zone – 1788 ± 16 Ma and charnockite from the Tapa Zone – 1761 ± 11 Ma) yield U–Pb crystallisation ages that span over approximately 80 Ma, suggesting a prolonged high-grade metamorphism or several separate events. U–Pb zircon age of one sample of charnockite is concordant with the Nd model age of partial melting of its host mafic granulite facies gneiss (intercept at 1.76 Ga). Linear geochemical trends and similar initial Nd isotopic compositions of mafic granulites and charnockites suggest their possible genetic relationship. From our new and previously published data it follows that the peak granulite metamorphic conditions and formation of tonalites and charnockites (850 °C and 6 kbar) in the Estonian basement occurred at 1788–1778 Ma. Then, the rocks cooled down, passing through the garnet closure temperature of approximately 650–700 °C at 1728 ± 24 Ma. The age of metamorphism of the Estonian granulites is lower than the metamorphic ages known from southern Finland, but it is similar to the age of metamorphism reported from the Belarus-Baltic Granulite Belt in Latvia.

AbstractA small, catalytically active metallopeptide (Nim6SOD, m6SOD=ACDLAC), which was derived from the nickel superoxide dismutase (NiSOD) active site was employed to study the mechanism of superoxide degradation, especially focusing on the protonation states of the NiII donor atoms, the proton source, and the role of the N‐terminal proton(s). Therefore, the NiII‐metallopeptide was studied at various pHs and temperatures using UV/Vis and NMR spectroscopy. These studies indicate a strong reduction of the pKa of the NiII‐ligating donor atoms, resulting in a fully deprotonated NiII active‐site environment. Furthermore, no titratable proton could be observed within a pH ranging from 6.5 to 10.5. This rules out a recently discussed adiabatic proton tunneling‐like hydrogen‐atom transfer process for the metallopeptides, not found in the native enzyme. Furthermore, variable‐temperature 1H NMR measurements uncovered an extended hydrogen‐bond network within the NiII active site of the metallopeptide similar to the enzyme. With respect to the deprotonated NiII active site, the residual N‐terminal proton, which is a prerequisite for catalytic activity, cannot act as proton source. Most likely, it stabilizes the NiII‐coordinated substrate in an end‐on fashion, thus allowing for an inner‐sphere electron transfer. Lastly, and unlike the enzyme, the catalytic rate constant of superoxide degradation by the metallopeptides was determined to be strongly pH dependent, suggesting bulk water to be directly involved in proton donation, which in turn strongly suggests the N‐terminal histidine to be the respective proton donor in the enzyme.

Immunohistochemical analysis of retraction pocket pars tensa of tympanic membrane in children. Identification of signs typical for cholesteatoma and support of retraction theory of cholesteatoma.a prospective study analysing 31 surgically removed retraction pockets.University Hospital, Children's Medical Centre Methods: Retraction pockets processed by a standard process for immunohistochemical analysis. The observed findings were specified using antibodies CD45 LCA (leukocyte common antigen), CD31 (platelet endothelial cell adhesion molecule), D2-40 (marker of lymphatic endothelium), MMP9 (marker of degradation of connective tissue extracellular matrix) and Ki67 (cellular marker of proliferation).All observed parameters except for MMP9 had a significantly higher incidence in retraction pocket stage III compared to stage II according to Charachon.We described immunohistochemical signs of retraction pocket pars tensa of tympanic membrane in children resulting in cholesteatoma. All the observed signs occur in the structure of matrix and perimatrix of cholesteatoma. A significantly higher incidence of all observed parameters except from MMP9 was proved in retraction pocket stage III, unlike in stage II. This observation proves the fact that retraction pocket is a progressive disease and is a procholesteatoma stage.

AbstractNovel liquid crystalline photochromic materials of the type 4‐R‐C6H4‐N=N‐C6H4‐O(CH2)n‐N(CH2CH2OH)2, where R is NO2, H, CN, O‐n‐C8H17, phenyl, 4‐O2NC6H4, were prepared. Some of them are photoconductive. These materials were used for the preparation of light‐sensitive polymers in which the photoactive moieties were attached to polyurethane chain. Photochromism of these compounds is based on trans‐cis isomerization of azobenzene group. An example of the photochromic activity is presented on solid solution of one material (R = O‐n‐C8H17, n = 5) in poly(methyl methacrylate) matrix.

article i nfo This paper deals with a simple and low-cost method developed to deposit hematite (α-Fe2O3) layers on a fluorine-doped tin oxide (FTO/F:SnO2) substrate by thermal decomposition of solid iron(III) chloride hexahydrate (FeCl3⋅6H2O). Deposition procedure takes place through chemical intermediate iron(III) oxide chloride (FeOCl) film. A crucial influence of atmosphere dynamics involved in the calcination process of FeOCl has been observed. As-deposited films were characterized by means of Conversion Electron Mossbauer Spectroscopy (CEMS), Grazing Angle X-Ray Diffractometry (GAXRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis. Final nanocrystalline hematite film with a cactus-field-like design consists of 20 nm thick porous crystal plates. A process of hematite doping by tin atoms from substrate coating is also discussed.

The bacterial diversity of Pectinatella magnifica colonies sampled from pounds in South Bohemia during the summer of 2012 was investigated. The bacterial counts determined after cultivation on modified yeast extract-tryptone agar (Oxoid) supplemented with glucose (1 g L−1) varied from 4.22 to 6.61 and from 1.30 to 6.85 log CFU/g for aerobes and anaerobes, respectively. Higher counts were found in the superficial structures of Pectinatella colonies than in the inner gelled mass. Neither a trend in bacterial numbers at the individual site during the season, nor correlations between bacterial counts in P. magnifica and the surrounding water were observed. Fifty-four isolates were identified by sequencing the 16S rRNA gene and through MALDI-TOF MS analysis. Species of Aeromonas and Aquitalea were the predominantly isolated bacteria, but members of Chryseobacterium, Herbaspirillum, Enterobacter, Lactococcus, Leuconostoc, Pseudomonas and Sphingomonas were also found. As listed genera are wildly distributed in different water, soil, and plant samples, we conclude that Pectinatella colonies are inhabited by environmental bacteria. Nevertheless, a symbiotic relationship of these bacteria with P. magnifica cannot be excluded.

Nanoparticles serving as a multifunctional and multiaddressable dopant to modify the properties of liquid crystalline matrices are developed by combining cobalt ferrite nanocrystals with organic ligands featuring a robust photosensitive unit and a source of chirality from the natural pool. These nanoparticles provide a stable nanocomposite when dispersed in achiral liquid crystals, giving rise to chiral supramolecular structures that can respond to UV-light illumination, and, at the same time, the formed nanocomposite possesses strong magnetic response. We report on a nanocomposite that shows three additional functionalities (chirality and responsiveness to UV light and magnetic field) upon the introduction of a single dopant into achiral liquid crystals.