Differentiation of Diastereoisomers of Protected 1,2-Diaminoalkylphosphonic Acids by EI Mass Spectrometry and Density Functional Theory

Electron ionization mass spectrometry and density functional theory (DFT) calculations have been used to study the fragmentation of diastereoisomers of protected 1,2-diaminoalkylphosphonic acids. The loss of a diethoxyphosphoryl group and the elimination of diethyl phosphonate were found to be competitive fragmentation processes, which can be used to differentiate both stereoisomers. Selective deuterated analogs and product- and precursor-ion mass spectra allowed the elucidation of the fragmentation mechanisms. The structures of the transition states and product ions were optimized using the density functional theory (DFT), and free energy calculations confirmed the observed differences in the formation and relative intensities of specific fragment ions.

Elucidation of activity of copper and copper oxide nanomaterials for electrocatalytic and photoelectrochemical reduction of carbon dioxide

Copper- and copper oxide–based materials are, in principle, promising components (supports, reactive sites, and visible light–absorbing semiconductors) of electrocatalysts and photocathodes for reduction of carbon dioxide. Electrochemical and photoelectrochemical approaches are generally suitable for the low-temperature CO₂-conversion to carbon-based simple organic fuels or utility chemicals.Different concepts of utilization, including nanostructuring, doping, admixing, preconditioning, modification, or functionalization of various copper- and copper oxide–based systems for catalytic electroreduction and photoelectrochemical reduction of CO₂ are elucidated, as well as important strategies to enhance the systems' overall activity and stability are discussed.     

Physicochemical Insight into Coordination Systems Obtained from Copper(II) Bromoacetate and 1,10-Phenanthroline

Two different coordination compounds of copper were synthesized from the same building blocks (1,10-phenanthroline, bromoacetate anions, and copper cations). The synthesis parameters were carefully designed and evaluated to allow the change of the resulting compounds molecular structure, i.e., formation of mononuclear (bromoacetato-O,O’)(bromoacetato-O)aqua(1,10-phenanthroline-N,N’)copper(II) and dinuclear (μ-bromido-1:2κ²)bis(μ-bromoacetato-1κO,2κO’)bis(1,10-phenanthroline-N,N’)dicopper(II) bromoacetate bromoacetic acid solvate. The crystal, molecular and supramolecular structures of the studied compounds were determined and evaluated in Hirshfeld analysis. The UV-Vis-IR absorption and thermal properties were studied and discussed. For the explicit determination of the influence of compounds structure on radiation absorption in UV-Vis range, density functional theory and time-dependent density functional theory calculations were performed.     

Synthesis and mesomorphism of tetrafluoro substituted 4-cyano oligophenyls

ABSTRACT

The synthesis and characterisation of new liquid crystal (LC) compounds based on terphenyl core are described. New family of dielectrically positive compounds presents alternative molecular approach to the conventional LC design. Correlations between molecular structure and mesomorphic properties for compounds being cyano terminated analogues as well as other known from the literature have been drawn. Compounds are characterised by ¹H NMR spectroscopy and mass spectrometry (electron ionisation) analysis. They show monotropic nematic behaviour in broad temperature range, confirmed by a polarising thermomicroscopy, differential scanning calorimetry. Detailed synthetic procedures are attached. Synthesised compounds stand as promising components of medium to highly birefringent liquid crystalline mixtures.     

A biological seeding particle approach for μ-PIV measurements of a fluid flow provoked by microorganisms

A biological seeding particle approach for μ-PIV measurements of a fluid flow provoked by microorganisms is presented. Results obtained with yeast cells and milk as tracer particles are compared. The use of milk enables more detailed visualisation and analysis of the fluid flow at higher magnifications.     

Development of a High-Fibre Multigrain Bar Technology with the Addition of Curly Kale

The aim of this study was to find the effect of kale and dietary fibre (DF) on the physicochemical properties, nutritional value and sensory quality of multigrain bars. A recipe of multigrain bars was prepared with the addition of fresh kale (20% and 30%) and DF preparations (apple, blackcurrant, chokeberry and hibiscus). The bars were baked at 180 °C for 20 min. These snack bars, based on pumpkin seeds, sunflower seeds, flaxseed and wholegrain oatmeal, are a high-calorie product (302–367 kcal/100 g). However, the composition of the bars encourages consumption. In addition to the ability to quickly satisfy hunger, such bars are rich in many natural ingredients that are considered pro-health (high fibre content (9.1–11.6 g/100 g), protein (11.2–14.3 g/100 g), fat (17.0–21.1 g/100 g, including unsaturated fatty acids), carbohydrates (20.5–24.0 g/100 g), as well as vitamins, minerals and a large number of substances from the antioxidant group. The addition of kale caused a significant increase of water content, but reduction in the value of all texture parameters (TPA profiles) as well as calorific values. The content of polyphenols was strongly and positively correlated with the antioxidant activity (r = 0.92). In the bars with 30% addition of kale (422 mg GA/100 g d.m.), the content of polyphenols was significantly higher than based ones (334 mg GA/100 g d.m.). Bars with the addition of the DF were characterized by a higher antioxidant activity, and the content of carotenoids, chlorophyll A and B and polyphenols. High sensory quality was demonstrated for all (from 4.8 to 7.1 on a 10-point scale). The addition of fibre preparations was also related to technological aspects and allows to create attractive bars without additional chemicals.     

Sample preparation procedure for the determination of polycyclic aromatic hydrocarbons in petroleum vacuum residue and bitumen

This paper describes a novel method of sample preparation for the determination of trace concentrations of polycyclic aromatic hydrocarbons (PAHs) in high-boiling petroleum products. Limits of quantitation of the investigated PAHs in materials of this type range from tens of nanograms per kilogram to <20 μg/kg. The studies revealed that in order to separate most of interferences from the analytes without a significant loss of PAHs, it is necessary to use size exclusion chromatography as the first step of sample preparation, followed by adsorption using normal-phase liquid chromatography. The use of orthogonal separation procedure described in the paper allows the isolation of only a group of unsubstituted and substituted aromatic hydrocarbons with a specific range of molar mass. The lower the required limit of quantitation of PAHs, the larger is the scale of preparative liquid chromatography in both steps of sample preparation needed. The use of internal standard allows quantitative results to be corrected for the degree of recovery of PAHs during the sample preparation step. Final determination can be carried out using HPLC-FLD, GC-MS, or HPLC-UV–VIS/DAD. The last technique provides a degree of identification through the acquired UV–VIS spectra.     

Application of liquid chromatography-tandem mass spectrometry method for the simultaneous quantitative analysis of propentofylline and its chiral metabolite M1 in rats

A sensitive and selective liquid chromatographic–electrospray ionization mass spectrometric method for the simultaneous determination of propentofylline and enantiomers of its active metabolite M1 in rat serum, cortex and hippocampus was developed and validated according to GLP procedures. Sample preparations were carried out by liquid–liquid extraction using diethyl ether after the addition of the internal standard (pentoxifylline). The dried residue was reconstituted in mobile phase and injected onto a Chiralpak AD column (10 µm, 250 × 4.6 mm i.d.). The limit of quantification for propentofylline in serum, cortex and hippocampus was set at 0.25 ng/mL and for enantiomers of its metabolite M1 at 1.25 ng/mL. The established LC/ESI‐MS/MS method has been successfully applied to an initial pharmacokinetic study of propentofylline and also to assessment of distribution of parent drug and enantiomers of its pharmacologically active metabolite M1 to cortex and hippocampus after intravenous administration of propentofylline to rats at a dose of 5 mg/kg. Copyright © 2010 John Wiley & Sons, Ltd.     

New one-pot technique to introduce charged nanoparticles into a lyotropic liquid crystal matrix

We present a new method to incorporate hydrophilic charged nanoparticles into the lyotropic liquid crystal (LLC) template. This method is based on the effect of the polymer-induced phase separation (PIPS) and consists of two steps. In the first step, the nanoparticles are mixed with a surfactant micellar solution. In the second step, upon addition of polymer, phase separation is induced and the LLC phase doped with the nanoparticles is formed. Columnar hexagonal and lamellar LLC templates are obtained with the PIPS method. The ordering of the LLC phase can be controlled by the amount of polymer added to induce phase separation. The method works both for the system of nonionic surfactants and polymers and ionic surfactants and polyelectrolytes. We demonstrate that the PIPS method enables the fabrication of the LLC templates doped with positively or negatively charged nanoparticles as well as with a mixture of oppositely charged nanoparticles in arbitrary proportions.     

Exact profiles of 13CO2 recovery in breath air after per oral administration of [13C]methacetin in two groups of different ages

The aim of this study is to determine if age is a factor influencing the results of a [¹³C]methacetin breath test (¹³C-MBT). Two groups of healthy volunteers, each comprising six men and six women, but differing in average age (Y=young, 25.1±0.6 years, MA=middle-aged;, 46.0±2.1 years) orally took 75 mg [¹³C]methacetin. Samples of expiratory air for ¹³CO₂ measurement were collected up to 48 h after intake of the substrate. A maximum momentary ¹³CO₂ breath exhalation of 37.0±2.6%dose/h was observed at 18 min (median, range: 9–30 min) in the young subjects and of 38.4±2.5%dose/h at 18 min (median, range: 12–30 min) in the middle-age volunteers. The cumulative ¹³C elimination in expiratory air was statistically significantly higher in the MA compared with the Y group as from 75 min up to 180 min, indicating a greater microsomal metabolic efficiency of the liver in the middle-aged healthy subjects. Gender, use of hormonal contraception, cigarette smoking, or body mass index did not modify the age-related effect on the cumulative ¹³C elimination in breath air. The study results imply a necessity of composing control groups well matched with regard to the age structure for a proper interpretation of clinical ¹³C-MBT results.