On BV-Solutions of Some Nonlinear Integral Equations

In this paper we prove uniqueness theorems for bounded variation (shortly: BV) solutions and continuous BV-solutions of the Hammerstein and the Volterra-Hammerstein integral equations. We investigate real-valued functions and functions with values in a Banach space. Submitted: August 16, 2001?Revised: September 13, 2002     

Sequestered alkyllithiums: why phenyllithium alone is suitable for betaine-ylide generation

The key step in the trans-selective modification of the Wittig reaction is the alpha-lithiation of the lithium bromide coordinated ylide-aldehyde adduct (the so-called "P-betaine"). Only phenyllithium effects this deprotonation rapidly and cleanly. Alkyllithiums (in particular, butyl-, sec-butyl-, and tert-butyllithium) react only sluggishly and incompletely, being tied up in very stable mixed aggregates with the lithium alkoxide part of the betaines.     

Distributional derivatives of functions of two variables of finite variation and their application to an impulsive hyperbolic equation

We give characterizations of the distributional derivatives D ^1,1, D ^1,0, D ^0,1 of functions of two variables of locally finite variation. Then we use these results to prove the existence theorem for the hyperbolic equation with a nonhomogeneous term containing the distributional derivative determined by an additive function of an interval of finite variation. An application of the above theorem to a hyperbolic equation with an impulse effect is also given.     

Modeling the electronic structures of the ground and excited states of the ytterbium atom and the ytterbium dimer: A modern quantum chemistry perspective

We present a comprehensive theoretical study of the electronic structures of the Yb atom and the Yb₂ molecule, respectively, focusing on their ground and lowest-lying electronically excited states. Our study includes various state-of-the-art quantum chemistry methods such as CCSD, CCSD(T), CASPT2 (including spin-orbit coupling), and EOM-CCSD as well as some recently developed pCCD-based approaches and their extensions to target excited states. Specifically, we scan the lowest-lying potential energy surfaces of the Yb₂ dimer and provide a reliable benchmark set of spectroscopic parameters including optimal bond lengths, vibrational frequencies, potential energy depths, and adiabatic excitation energies. Our in-depth analysis unravels the complex nature of the electronic spectrum of Yb₂, which is difficult to model accurately by any conventional quantum chemistry method. Finally, we scrutinize the bi-excited character of the first excited state and its evolution along the potential energy surface.     

Investigation of 4-(nitrophenylamino)pent-3-en-2-ones and 4-(nitrobenzylamino)pent-3-en-2-ones by electron ionization mass spectrometry. Observation of characteristic ortho effects

The compounds 4-(phenylamino)pent-3-en-2-ones (1-3) and 4-(benzylamino)pent-3-en-2-ones (4-6) substituted with a nitro group on the aromatic ring were studied by electron ionisation mass spectrometry (EIMS). It was deduced that the compounds 1-3 are converted into the tautomeric 4-(arylimino)pentan-2-one during the EI process. Mass spectrometric decompositions of ortho-substituted derivatives (1 and 4) were found to be different from those observed for meta- and para-isomers. The fragmentation pathways are discussed on the basis of data from linked B/E and B(2)/E scans, mass-analysed ion kinetic energy (MIKE) spectra, accurate mass measurements and isotope labelling.     

Thermal analysis and spectroscopic characteristics of tetrabutylammonium tetrachloroferrate(III)

The IR, far-IR, Raman and Mössbauer spectra have been utilized to identify a new compound consisting of a tetrachloroferrate(III) anion and a tetrabutylammonium cation [(C₄H₉)₄N][FeCl₄]. Its degradation has been studied by thermal analysis using TG, TG-MS, DTG and DTA, as well as DSC techniques. The measurements were run in static air and in argon atmosphere. Solid residues were identified by elemental analysis, far-IR and Mössbauer spectroscopy. The discussion was focused on processes proceeding during the first step of the thermal decomposition.     

Structural and Physicochemical Characteristics of Tetrabutylammonium Tetrahalogenoferrates(III), [(C4H9)4N][FeBr4−nCln]

A series of tetrahalogenoferrates(III), [FeBr_4?nCl_n]^? (n=0‐4) stabilized with the tetrabutylammonium cation, of general formula [(C₄H₉)₄N][FeBr_4?nCl_n], has been synthesized. The crystal and molecular structure of [(C₄H₉)₄N][FeCl₄] was determined. The iron cation adopts slightly distorted tetrahedral coordination with two opposite angles smaller than tetrahedral one, two equal to tetrahedral and two larger than tetrahedral. The bond valences were computed. The total valence of iron atom is equal to 3.08. In the structure can be found only one hydrogen bond C(1)–H···Cl. Except mentioned there are no unusually intermolecular short contacts between ions existing in the structure. All [(C₄H₉)₄N][FeBr_4?nCl_n] (n=0‐4) compounds are isostructural in solid state. On the basis of conductometric measurements, relative stabilities of the anions have been estimated in methanol (MeOH), dimethyl sulfoxide (DMSO), acetone (AC), acetonitrile (AN) and dichloromethane (CH₂Cl₂) representing both polar (including amphiprotic and aprotic) as well as non‐polar solvents. Further, the dissociation constants of the compounds were calculated from the expanded Pitt's conductivity equation. The results of the conductometric measurements were supported by electronic spectra.     

Synthesis, crystal structures and the preliminary evaluation of the new dibenzotetraaza[14]annulene-based DNA/RNA binding agents

A series of water-soluble dicationic dibenzotetraaza[14]annulenes have been prepared in order to examine their interactions with nucleic acids. Pendant water-solubilizing N-pyridinium, 4,4′-bipyridinium and N-methyl pyridinium moieties have been attached to the central core via linkers generated by direct N-alkylations and ester creating couplings, respectively. The crystal structures of derivatives equipped with 3-(N-pyridinium-1-yl)propyl and 3-(4,4′-bipyridinium-1-yl)propyl substituents have been determined. Interactions with ct-DNA have been studied and evidenced by means of spectrophotometric titrations with Scatchard analysis and thermal denaturation experiments.     

Linnaea borealis L. var. borealis—In Vitro Cultures and Phytochemical Screening as a Dual Strategy for Its Ex Situ Conservation and a Source of Bioactive Compounds of the Rare Species

Linnaea borealis L. (Twinflower)—a dwarf shrub in the Linnaeeae tribe of Caprifoliaceae family—is distributed across the Northern Hemisphere. By means of this study, a reliable protocol for efficient micropropagation of uniform L. borealis L. var. borealis plantlets has been provided for the first time; callus culture was also established. Different initial explants, types of cultures, media systems, and plant growth regulators in Murashige and Skoog (MS) media were tested. Agitated shoot cultures in the liquid media turned out to be the best system for the production of sustainable plant biomass. After stabilization of the callus lines, the highest growth index (c.a. 526%) was gained for callus maintained on MS enriched with picloram. TLC and UHPLC-HESI-HRMS analysis confirmed the presence of phenolic acids and flavonoids, and for the first time, the presence of iridoids and triterpenoid saponins in this species. Multiplication of L. borealis shoot culture provides renewable raw material, allowing for the assessment of the phytochemical profile, and, in the future, for the quantitative analyses and the studies of the biological activity of extracts, fractions, or isolated compounds. This is the first report on in vitro cultures of traditionally used L. borealis rare taxon and its biosynthetic potential.