Synthesis and characterization of LnFeO<Subscript>3</Subscript> pigments

This work is focused on determination of the optimum firing temperature which leads to formation of the compounds LnFeO₃ with good pigment-application properties (Ln=Gd, La, Yb, Tm, Lu). Based on results of thermal analysis the compounds were prepared by the solid-state reaction at temperature 900 and 1000°C. Colours of pigments vary depending on type of used lanthanoid (from light sienna to dark brown) and also on the type of precursor. Generally, the compounds prepared from iron oxide have more interesting color properties. Colour of these compounds is brighter and deeper. Increasing of the calcination temperature from 900 to 1000°C causes the darkening of colour. The most problably, the darkening is connected with partial reduction of Fe³⁺ to Fe²⁺.     

On quasiconformal deformations of the universal hyperbolic solenoid

We investigate the Teichmüller metric and the complex structure on the Teichmüller space (H _∞) of the universal hyperbolic solenoid H _∞. In particular, a version of the Reich-Strebel inequality for H _∞ is obtained. As a consequence, we show that the Teichmüller type Beltrami coefficients determine unique geodesics in (H _∞), and we compute the infinitesimal form of the Teichmüller metric. In addition, we show that a Beltrami coefficient is Teichmüller extremal if and only if it is infinitesimally extremal. Finally, we show that the Kobayashi metric on (H _∞) equals the Teichmüller metric.     

The Teichmüller distance between finite index subgroups of $${PSL_2(\mathbb{Z})}$$

For a given , we show that there exist two finite index subgroups of which are -quasisymmetrically conjugated and the conjugation homeomorphism is not conformal. This implies that for any there are two finite regular covers of the Modular once punctured torus T ₀ (or just the Modular torus) and a -quasiconformal map between them that is not homotopic to a conformal map. As an application of the above results, we show that the orbit of the basepoint in the Teichmüller space T(S ^p ) of the punctured solenoid S ^p under the action of the corresponding Modular group (which is the mapping class group of S ^p [6], [7]) has the closure in T(S ^p ) strictly larger than the orbit and that the closure is necessarily uncountable.      

Effect of PHB on the properties of biodegradable PLA blends

Blends of biodegradable polymers polylactic acid/thermoplastic starch/polyhydroxybutyrate (PLA/TPS/PHB) were prepared using a twin-screw extruder. The TPS content was constant (50 %) and the PHB content in the blends was gradually changed from 0 mass % to 20 mass %. TPS was prepared by melting, where a mixture of native starch, water and glycerol was fed into the twinscrew extruder. Average temperature of extrusion was 180°C and the concentration of glycerol was 40 mass %. Influence of the PHB concentration in the blend and that of the processing technology on the mechanical and rheological properties of the PLA/PHB composition containing TPS were studied. Mechanical properties were measured 24 h after the film and monofilament preparation and also after the specific storage time to study the effect of storage on the properties. The results indicate that differences in morphology strongly influence the mechanical properties of the studied materials with identical material composition.     

Repetitive inductions of bioluminescence of <Emphasis Type="Italic">Pseudomonas putida</Emphasis> TVA8 immobilised by adsorption on optical fibre

Physico-chemical models of the interactions of cells with solid surfaces, which use contact angles and zeta potentials, indicated more facile adsorption of cells of Pseudomonas putida TVA8 on the quartz surface after its treatment with 3-aminopropyltriethoxysilane (APTES). A whole-cell optical fibre sensor of toluene was prepared by the adsorption of P. putida TVA8, bacteria producing light in contact with toluene on the wider end of APTES- treated quartz tapered optical fibre. The results of the measurements of luminescence from both sides of the layer of adsorbed cells were compared. Over the 135 days trial, the fibre biosensor was repetitively induced with toluene solution (26.5 mg L^?1) 68 times. The intensities of bioluminescence gradually decreased due to release of the adsorbed cells and they were only temporarily restored by the addition of nutrients. The intensities of bioluminescence induced with contaminated ground water were lower than in the mineral medium (MSM) with the same content of toluene.     

Plant waste residues as inducers of extracellular proteases for a deuteromycete fungus <Emphasis Type="Italic">Trichoderma atroviride</Emphasis>

The ability of Trichoderma atroviride F-534 to utilize plant waste byproducts derived from processing of vegetables and fruits, as the major source of organic carbon and nitrogen for growth and protease production, was tested. The submerged cultivation of T. atroviride F-534 in the mineral base of the Czapek–Dox medium supplemented with plant waste byproducts resulted into copious biomass formation and was accompanied by secretion of several proteolytic enzymes. Zymography analysis of fungal culture filtrates showed that the high-molecular weight (HMW) protease(s) (from 100 kDa to 230 kDa) represent the major portion of secreted enzymes. Serine-type proteases and metalloproteases were predominant, although all known types of proteolytic enzymes were detected dependent on the type of inducer (substrate). The most conspicuous feature of secreted proteases was that the zymography patterns were unique for each plant material tested. These results confirm our previous finding obtained with purified proteins. Results also suggest that HMW protease(s) may participate in the heterotrophic/saprophytic/mode of life of this fungus. Their identity remains, however, obscure.     

Electrochemical/chemical synthesis of hydroxyapatite on glassy carbon electrode for electroanalytical determination of cysteine

Journal of Solid State Electrochemistry - Hydroxyapatite (HAp)-modified glassy carbon (HAp/GC) electrode was prepared through a two-step chemical reaction process: Hydrogenphosphate, firstly formed...     

Analytical study of rhenium complexes with pyrogallol and catechol

Selected rhenium complexes with pyrogallol (1,2,3-trihydroxybenzene) and catechol (1,2-dihydroxybenzene) as strongly bound ligands were prepared by a reaction of rhenium precursor tetrabutylammonium-tetrachlorooxorhenate with twofold molar excess of ligand in presence of various amounts of triethylamine. The structures of formed complexes and their consequent reaction products were estimated by means of mass spectrometry with electrospray ionization. The kinetics of reactions in course of complex formation and consequent decomposition were primarily followed by UV–Vis absorption spectra measurement, complemented by single or continuous electrospray mass spectrometry analyses.     

Some irreducibility and indecomposability results for truncated binomial polynomials of small degree

In this paper, we show that the truncated binomial polynomials defined by \(P_{n,k}(x)={\sum }_{j=0}^{k} {n \choose j} x^{j}\) are irreducible for each k≤6 and every n≥k+2. Under the same assumption n≥k+2, we also show that the polynomial P _n,k cannot be expressed as a composition P _n,k (x) = g(h(x)) with \(g \in \mathbb {Q}[x]\) of degree at least 2 and a quadratic polynomial \(h \in \mathbb {Q}[x]\). Finally, we show that for k≥2 and m,n≥k+1 the roots of the polynomial P _m,k cannot be obtained from the roots of P _n,k , where m≠n, by a linear map.     

Structural analysis and antitumor potential of novel 5,6-disubstituted-17a-homo-17-oxa-androstane derivatives

Starting from 3β-acetoxy-17a-homo-17-oxa-androst-5-en-16-one (1) and in the reaction with N-bromoacetamide (NBA) and perchloric acid, the 5α-bromo-6β-hydroxy (2), 5β,6β-epoxy (3) and 5α,6β-dibromo (4) derivatives were obtained. The structure of compounds 2–4, particularly stereochemistry at C5 and C6, is established by detailed NMR and X-ray analysis. The in vitro antiproliferative activity of newly synthesized compounds 2–4 against six human tumor cell lines was evaluated. All three compounds showed a significant toxicity toward hormone-independent breast adenocarcinoma MDA-MB-231 and cervical carcinoma cells HeLa, while dibromo derivative 4 was active toward five human cancer cell lines. These new 5,6-disubstituted-D-homolactone steroidal compounds have also displayed selectivity toward cancerous cell lines against inactivity found for noncancerous control cell line. This selectivity was not found for control compound, well-known chemotherapy drug cisplatin.