Cyclic dialkylindium amides: new structural information and ultra-purification using inorganic and inorgano-organic layered materials

New data on some cyclic dimethyl- and diethylindium-amides were obtained. X-ray structure of pyrrolidinodimethylindium was determined. The molecule is centrosymmetric with square-planar In₂N₂ base and distorted tetrahedral metal environment similar to that of known dialkylindium amides, the cyclic amido-ligands are present in an envelope conformation. A novel material- and energy-saving procedure for sorption ultra-purification of highly sensitive organometallic compounds in absolute non-polar media was developed. Advanced inorganic and inorgano-organic crystalline layered materials possessing enhanced affinity towards selected ions or molecules were applied for the sorption treatment.     

Spectroscopic and Morphological Properties of Divinylbenzoxazolylbiphenyl Thin Films

The thin organic films based on 4,4′-bis-[(Z)-1-(1,3-benzoxazol-2-yl-2-ethenyl)]biphenyl and its partly fluorinated derivatives are studied. Absorption, luminescence, and excitation spectra, luminescence decay and film morphology were found to depend sensitively on the changes in molecule structure, nature and temperature of the substrate, as well as the thermovacuum deposition rate, being the origins of bad reproducibility of the optical properties of such films. Molecular aggregation with chromophore dipoles arranged parallel to each other has been observed in absorption and luminescence spectra. The fluorescence characteristics can be explained by the combination of radiation of aggregated and non-aggregated molecules. The main characteristics of the molecules under study are calculated using DFT approach. The unusual behaviour of photodegradation in fluorinated film is found.     

Inverse scattering theory for one-dimensional Schrödinger operators with steplike finite-gap potentials

We develop direct and inverse scattering theory for one-dimensional Schrödinger operators with steplike potentials which are asymptotically close to different finite-gap potentials on different half-axes. We give a complete characterization of the scattering data, which allows unique solvability of the inverse scattering problem in the class of perturbations with finite second moment.     

Cauchy problem for a class of parabolic systems of Shilov type with variable coefficients

In the case of initial data belonging to a wide class of functions including distributions of Gelfand-Shilov type we establish the correct solvability of the Cauchy problem for a new class of Shilov parabolic systems of equations with partial derivatives with bounded smooth variable lower coefficients and nonnegative genus. We also investigate the conditions of local improvement of the convergence of a solution of this problem to its limiting value when the time variable tends to zero.     

Scattering Theory with Finite-Gap Backgrounds: Transformation Operators and Characteristic Properties of Scattering Data

We develop direct and inverse scattering theory for Jacobi operators (doubly infinite second order difference operators) with steplike coefficients which are asymptotically close to different finite-gap quasi-periodic coefficients on different sides. We give necessary and sufficient conditions for the scattering data in the case of perturbations with finite second (or higher) moment.     

Amino Acid Functionalized Superparamagnetic Nanoparticles Inhibit Lysozyme Amyloid Fibrillization

Nanoparticles have great potential to be used in various biomedical applications, including therapy or diagnosis of amyloid-related diseases. The physical and chemical properties of iron oxide superparamagnetic nanoparticles (MNPs) functionalized with different amino acids (AAs), namely, with lysine (Lys), glycine (Gly), or tryptophan (Trp), have been characterized. The cytotoxicity of nanoparticles and their effect on amyloid fibrillization of lysozymes in vitro was also verified. The AA-MNPs under study are nontoxic to human SHSY5Y neuroblastoma cells. Moreover, the AA-MNPs were able to significantly inhibit lysozyme amyloid fibrillization and destroy amyloid fibrils. Kinetic studies revealed that the presence of AA-MNPs affected lysozyme fibrillization, namely, the lag phase and steady-state phase of the growth curves. The most effective activities were observed for Trp-MNPs, which revealed the importance of aromatic rings in the structure of AAs used as coating agents. The obtained results indicate the possible application of these AA-MNPs in the treatment of amyloid diseases associated with lysozyme or other amyloidogenic proteins.     

Homogenization of the Spectral Problem for Periodic Elliptic Operators with Sign-Changing Density Function

The paper deals with the asymptotic behaviour of spectra of second order self-adjoint elliptic operators with periodic rapidly oscillating coefficients in the case when the density function (the factor on the spectral parameter) changes sign. We study the Dirichlet problem in a regular bounded domain and show that the spectrum of this problem is discrete and consists of two series, one of them tending towards +∞ and another towards −∞. The asymptotic behaviour of positive and negative eigenvalues and their corresponding eigenfunctions depends crucially on whether the average of the weight function is positive, negative or equal to zero. We construct the asymptotics of eigenpairs in all three cases.     

Effects of Phytohormones and Jasmonic Acid on Glucosinolate Content in Hairy Root Cultures of Sinapis alba and Brassica rapa

Although some study have established hairy root cultures from brassicaceous plants with glucosinolates (GS) as characteristic secondary metabolite, studies are missing which compare hairy roots with the corresponding mother plants. Therefore, two different plant species—Sinapis alba and Brassica rapa subsp. rapa pygmeae teltoviensis—were transformed with the Agrobacterium rhizogenes strain A4. Aliphatic and indolyl GS were present in B. rapa, exhibiting larger quantities in leaves than in roots. Aromatic p-hydroxybenzyl GS were found particularly in the leaves of S. alba. However, the proportion of indolyl GS increased suddenly in transformed hairy roots of S. alba and B. rapa. Cultivation with the phytohormone kinetin (0.5 mg?L^?1) enhanced GS accumulation in B. rapa hairy roots, however not in S. alba, but 2,4-D (0.4 mg?L^?1) induced de-differentiation of roots in both species and reduced GS levels. GS levels especially of 1-methoxyindol-3ylmethyl GS increased in hairy roots in response to JA, but root growth was inhibited. While 2 weeks of cultivation in 100 to 200 μM JA were determined at optimum for maximum GS yield in S. alba hairy root cultures, 4 weeks of cultivation in 50 to 100 μM JA was the optimum for B. rapa.     

Chiral memory and self-replication study of porphyrin and bilirubin aggregates formed on polypeptide matrices

Porphyrin heteroaggregates composed of meso-tetrakis(N-methylpyridinium-4-yl)porphinatocopper(II) and meso-tetrakis(4-sulfonatophenyl)porphyrin formed in the presence of a polyglutamic matrix possess chiral memory and an ability to self-replicate their supramolecular structures. By means of electronic circular dichroism spectroscopy, it has been shown that the self-replication process is not influenced by changes in pH or ionic strength. The average molecular weight of the polyglutamic matrix used for porphyrin aggregate preparation plays a crucial role with regard to the form of the resulting CD spectrum. In the second part of our study, a complex composed of polylysine and bilirubin as a model system for a structured homoaggregate formed on the chiral matrix has been tested for chiral memory phenomena. The results indicate that the bilirubin homoaggregate shows chiral memory.     

Pressure-induced order transition in nanodot-forming diblock copolymers at the air/water interface

Understanding and controlling the processes in block copolymer (BC) monolayers at the air/water interface during surface area compression is a key issue for producing ultrathin films of predetermined morphology with well-defined order and known dimensions. Langmuir isotherms of nanodot-forming BC monolayers generally display a plateau indicative of a 2D phase transition, which has been the subject of various interpretations in the literature. Here, based on investigations of Langmuir-Blodgett and Langmuir-Schaefer nanodot films of PS-P4VP mixed with 3-n-pentadecylphenol (PDP), we show by atomic force microscopy (AFM) that it involves a change in nanodot packing order (from quasi-hexagonal to quasi-square), argued to be a general phenomenon for nanodot BC monolayers. It is accompanied by system-specific conformational changes (as discussed in previous literature), which, in the present case, implicate PDP alkyl chain ordering, as deduced previously from in situ infrared data and indirectly supported here by AFM imaging.