Nephelauxetic effect in some lanthanide(III) complexes with 2-pyridineamidoxime

Diffuse reflectance spectra of tris-(2-pyridineamidoximato) lanthanide(III) chlorides, [Ln(PAO)₃] Cl₃, Ln = Pr, Nd, Sm, Eu, Dy and Ho, in the visible region have been recorded for the first time. Shifts (100–150 cm^?1) of their f ? f transitions have been observed towards lower wave numbers in relation to the lanthanide aquoions. These data have been used for evaluation of the nephelauxetic ratio β′ and the covalency parameters b^{$\text{1}\text{2}$}. Sublevels with J = 0 and J = $\text{1}\text{2}$ as well as hypersensitive bands, obeying the selection rules|ΔJ|?2,|ΔL|?2, have been considered. The results have been discussed in terms of weak covalent bonding between the lanthanide ion and the nitrogen atoms of the ligands.     

Amphiphilic branched polymers as antimicrobial agents

Cationic amphiphilic polymers were prepared from PEI and functional ethylene carbonates bearing cationic, hydrophobic or amphiphilic groups. The polymers are designed to exhibit antimicrobial properties. In a one-step addition, different functional ethylene carbonates were added to react with the primary amine groups of PEI. The water soluble polymers were studied regarding their ability to form soluble aggregates. Their hydrodynamic radii, their inhibition potential against proliferation of E. coli and their hemolytic potential were determined. A structure-property relationship was established by analyzing the antimicrobial activity as a function of the ratio of alkyl to cationic groups, length of the alkyl chains, and molecular weight of the PEI.     

Electrical and optical properties of ZnO thin films prepared by magnetron rf sputtering—influence of Al, Er and H

The influence of Al, Er and H in ZnO thin films (ZnO:Al, ZnO:Er and ZnO:H) deposited by magnetron sputtering at different substrate temperatures, T_s, on their optical, structural and electrical properties was investigated. X-ray diffraction (XRD) analyses show an improvement of the crystalline structure with increasing T_s. The optical band gap, , of the films, from transmission and reflection spectra, ranged from 3.27 to 3.41 eV. The Urbach band tail width was also calculated. Incorporation of Al and Er resulted in a reduced and an increased resistivity, ρ, respectively, and an increase in the Urbach tail width in both cases. However, sputtering in an Ar+H₂ gas mixture led to an increase in ρ and an improvement in the structural order of the films. A discussion of the influence of T_s and of Al, Er and H on the properties is presented.     

Investigation of lutetium rydberg states by laser multistep resonance ionization spectroscopy

Laser multistep excitation and electric-field ionization spectroscopy have been used to investigate experimentally highly excited states (HES) of lutetium in the vicinity of the first ionization limit. The investigation includes the measurement of energy levels (ionic signal vs last transition frequency) and radiation lifetime (ionic signal vs ionizing electric-field pulse delay) of the states investigated. Even Rydberg states of 4f ¹⁴ 6s ² nd have been observed with two-step laser excitation. The maximum experimental error is 0.3 cm^?1 for the energy and 20% for the radiation lifetime measurements. This is the very first time that results for the lifetimes as well as for a large part of the energy values have been obtained. Our present experimental results compare well with previously calculated values obtained by relativistic perturbation theory using the zero-order model approximation, and with the available experimental values.     

Comparative direct infusion ion mobility mass spectrometry profiling of Thermus thermophilus wild-type and mutant ∆cruC carotenoid extracts

The major carotenoid species isolated from the thermophilic bacterium Thermus thermophilus HB27 have been identified as zeaxanthin–glucoside–fatty acid esters (thermozeaxanthins and thermobiszeaxanthins). Most of the genes of the proposed T. thermophilus carotenoid pathway could be found in the genome, but there is less clarity about the genes which encode the enzymes performing the final carotenoid glycosylation and acylation steps. To get a further insight into the biosynthesis of thermo(bis)zeaxanthins in T. thermophilus, we deleted the megaplasmid open reading frame TT_P0062 (termed cruC) by both exchanging it with a kanamycin resistance cassette (ΔcruC:kat) and by generating a markerless gene deletion strain (ΔcruC). A fast and efficient electrospray ionization–ion mobility–time-of-flight mass spectrometry method via direct infusion was developed to compare the carotenoid profiles of wild type and mutant T. thermophilus cell culture extracts. These comparisons revealed significant alterations in the carotenoid composition of the ΔcruC mutant, which was found to accumulate zeaxanthin. This is the first experimental evidence that the ORF encodes the glycosyltransferase enzyme necessary for the glycosylation of zeaxanthin in the final modification steps of the thermozeaxanthin biosynthesis in T. thermophilus HB27. Also, the proposed method for direct determination of carotenoid amounts and species in crude acetone extracts represents an improvement over existing methods in terms of speed and sensitivity and may be applicable in high-throughput analyses of other terpenoids as well as other important bacterial metabolites like fatty acids and their derivatives.

Space-group multiplicities of polymorphs of inorganic compounds and lattice enthalpies

The relationships between lattice enthalpies (LEs) and multiplicities of points in general positions or orders of the point groups of the space groups have been studied for 71 inorganic compounds exhibiting at least two polymorphs. The LEs of the ionic crystals have been obtained through the Born–Haber (BH) thermochemical cycle, including halides, chalcogenides, oxohalides, and binary and complex oxides. It has been found for the range of LEs (600–39,000 kJ mol^?1) and relevant crystal structures that: (i) most of the polymorphs with higher multiplicities correspond to those stable under standard conditions compared to the lower-in-stability polymorphs and (ii) the products of multiplicity times order depend hyperbolically on the LE per unit symmetry point in general position.     

Kinematics of haylage bale in 3D space as a body of one fix point and two rotations

This paper presents mechanical-mathematical matrix simulation of haylage bale kinematics in 3D space as a body of one fix point and two rotations. There are defined: the matrices of transition from the coordinate system connected stationary with the body to the starting (global) coordinate system; the position vector, absolute linear speed and absolute linear acceleration of bale arbitrary point; the vector of absolute angular velocity and absolute angular acceleration projected in the starting and in the local coordinate systems of the body. Numerical example is provided.     

Synthesis, spectroscopic and structural elucidation of 3-ethylamino-2-(4-nitro-benzoyl)-but-2-enoic acid phenylamide

3-Ethylamino-2-(4-nitro-benzoyl)-but-2-enoic acid phenylamide is synthesized, isolated, spectroscopical and structural characterized by means of linear-polarized IR-spectroscopy (IR-LD) of oriented solids as a colloidal suspension in nematic liquid crystal. The experimental IR-band assignment and structural information are supported by quantum chemical calculations at MP2 and B3LYP level of theory and 6-311++G** basis set. The geometry is characterized by two inramolecular hydrogen bonds of NH...O=C with bond lengths of 2.589 and 3.449 angstroms. The NHO angles are 142.1(3) degrees and 125.8(4) degrees , respectively. A transoide configuration of amide fragments is predicted with a torsion NH-C=O angle of 150.6 degrees . Phenyl fragments are mutually perpendicular oriented closing an angle of 92.6 degrees .