In the paper fast chromatographic method for separation of lysozyme PEG positional isoforms at low pressure using monoliths is described. Such method can be used for process analytical technology (PAT)
COBISS.SI-ID: 1536812483
The electrochemical behavior of Fe(III) in the presence of phytate ligand was investigated by cyclic voltammetry on the polycrystalline gold and mercury drop electrodes in the pH range between 1.5 and 10, and ligand to metal molar ratio from 0 to 20. Complexation of Fe(III) and Fe(II) by phytate ligand (L) reflects in (i) shift of the formal potential E0’ of the Fe(III)/Fe(II) redox couple into the negative direction, and (ii) an increased irreversibility of the redox processes. Change of the formal potential originate from higher stability of the Fe(III)L complex with respect to Fe(II)L complex, however, due to the slow charge transfer control of the redox processes apparent stability constants calculated from voltammetric data may lead to an overestimation of their true values. Irreversible reduction of Fe(III)L to Fe(II)L is diffusion controlled and involves one proton per one electron on both electrodes. Reduction of Fe(III) phytate complex to Fe(II)L depends on the pH and at pH ( 5 proceeds via [FeIIIH5L]4– species, but at higher pH less protonated [FeIIIH3L]6– become the major reacting species. An almost stepwise change of the reduction peak potential for more than 0.8 V into the negative direction around pH 5 indicate that both reactants have quite different stability and/or structure. We predicted that electronic configuration and affinity of Fe(III) ions for the octahedral coordination induce the inversion of phytate ligand from its equatorial to the axial conformation which form more than ten orders of magnitude more stable Fe(III)L complexes. Fe (II)L intermediate generated on the electrode is strongly adsorbed on both gold and mercury electrodes, and totally irreversible reduction of Fe(II)L complex to the Fe metal was observable at mercury electrode as well. From Fe(III/II)L peak analysis on the mercury electrode the cathodic charge transfer coefficient of 0.68 was found, for [FeIIIH3L]6– reacting species the diffusion coefficient of (9.1 ±0.1) x10–7cm2/s was estimated, and the rate constant k0 of 7.8 x10–5 cm/s was calculated.
COBISS.SI-ID: 1536395203
The manuscript describes study of new materials which were found in petroleum deposits. We are talking about diamondoid compounds whose use value has not been fully explored. In this study structural characterization of tetramantanes using high-resolution NMR spectroscopy was investigated. The structure of the two high symmetry and one chiral isomer of tetramantane was determined using chemical shifts and coupling constants data. These findings should be valuable in future NMR studies of diamondoids/nanodiamonds of increasing size [COBISS.SI ID 1536615875].
COBISS.SI-ID: 1536615875
Biomolecular profiling with Fourier-Transform Infra Red Microscopy was performed to distinguish the Zn2+-mediated effects on the crustacean (Porcellio scaber) digestive glands from the ones elicited by the ZnO nanoparticles (NPs). The exposure to ZnO NPs or ZnCl2 (1500 and 4000 µg Zn/g of dry food) activated different types of metabolic pathways: some were found in the case of both substances, some only in the case of ZnCl2, and some only upon exposure to ZnO NPs. Both the ZnO NPs and the ZnCl2 increased the protein (∼1312 cm−1; 1720–1485 cm−1/3000–2830 cm−1) and RNA concentration (∼1115 cm−1). At the highest exposure concentration of ZnCl2, where the effects occurred also at the organismal level, some additional changes were found that were not detected upon the ZnO NP exposure. These included changed carbohydrate (most likely glycogen) concentrations (∼1043 cm−1) and the desaturation of cell membrane lipids (∼3014 cm−1). The activation of novel metabolic pathways, as evidenced by changed proteins’ structure (at 1274 cm−1), was found only in the case of ZnO NPs. This proves that Zn2+ are not the only inducers of the response to ZnO NPs. Low bioavailable fraction of Zn2+ in the digestive glands exposed to ZnO NPs further supports the role of particles in the ZnO NP-generated effects. This study provides the evidence that ZnO NPs induce their own metabolic responses in the subtoxic range.
COBISS.SI-ID: 3553103