Supramolecular Solvent-Based Microextraction of Selected Anticonvulsant and Nonsteroidal Anti-Inflammatory Drugs from Sediment Samples

The increase in the production and consumption of pharmaceuticals increases their presence in the global environment, which may result in direct threats to living organisms. For this reason, there is a need for new methods to analyze drugs in environmental samples. Here, a new procedure for separating and determining selected drugs (diclofenac, ibuprofen, and carbamazepine) from bottom sediment and water samples was developed. Drugs were determined by ultra-high performance liquid chromatography coupled with an ultraviolet detector (UHPLC-UV). In this work, a universal and single-step sample treatment, based on supramolecular solvents (SUPRAS), was proposed to isolate selected anticonvulsants and nonsteroidal anti-inflammatory drugs (NSAIDs) from sediment samples. The following parameters were experimentally selected: composition of the supramolecular solvent (composition THF:H₂O (v/v), amount of decanoic acid), volume of extractant, sample mass, extraction time, centrifugation time, and centrifugation speed. Finally, the developed procedure was validated. A Speedisk procedure was also developed to extract selected drugs from water samples. The recovery of analytes using the SUPRAS procedure was in the range of 88.8–115%, while the recoveries of the Speedisk solid-phase extraction procedure ranged from 81.0–106%. The effectiveness of the sorption of the tested drugs by sediment was also examined.     

Potassium Poly(Heptazine Imide): Transition Metal‐Free Solid‐State Triplet Sensitizer in Cascade Energy Transfer and [3+2]‐cycloadditions

Polymeric carbon nitride materials have been used in numerous light‐to‐energy conversion applications ranging from photocatalysis to optoelectronics. For a new application and modelling, we first refined the crystal structure of potassium poly(heptazine imide) (K‐PHI)—a benchmark carbon nitride material in photocatalysis—by means of X‐ray powder diffraction and transmission electron microscopy. Using the crystal structure of K‐PHI, periodic DFT calculations were performed to calculate the density‐of‐states (DOS) and localize intra band states (IBS). IBS were found to be responsible for the enhanced K‐PHI absorption in the near IR region, to serve as electron traps, and to be useful in energy transfer reactions. Once excited with visible light, carbon nitrides, in addition to the direct recombination, can also undergo singlet–triplet intersystem crossing. We utilized the K‐PHI centered triplet excited states to trigger a cascade of energy transfer reactions and, in turn, to sensitize, for example, singlet oxygen (¹O₂) as a starting point to synthesis up to 25 different N‐rich heterocycles.     

Synthesis of Monofunctionalized Silsesquioxanes (RSiMe2O)(iBu)7Si8O12 via Alkene Hydrosilylation

The research presented in this work comprehensively describes hydrosilylation of a wide spectrum of alkenes which contain one or more reactive groups with (HSiMe₂O)(iBu)₇Si₈O₁₂, in the presence of different types of catalysts. Special attention is paid to the influence of alkene, catalyst, and reaction conditions on process effectiveness and selectivity by the precise monitoring of the experiments with in situ FTIR and NMR spectroscopies. More than twenty silsesquioxanes bearing reactive groups (OH, Br, NR₂, CO, COOR, NCO, epoxy, SiR₃) commonly used in organic and polymer chemistry, were obtained, isolated and characterized by ¹H, ¹³C, ²⁹Si NMR and MALDI TOF. Importantly, in the presented syntheses, commercially available reagents and catalysts were used, meaning that the presented methods could be easily repeated, rapidly scaled up, and widely applied.     

Very high frequency EPR — 94 GHz instrument and applications to primary reaction centers from photosynthetic red bacteria and to other disordered systems

There are many advantages to carrying out electron paramagnetic resonance experiments at very high frequencies, either as part of a multifrequency strategy for solving problems or for special characteristics of high frequencies. These special characteristics include the potential for high point sensitivity, enhanced resolution, separation of similar species, altered sensitivity to motion, suppression of motional effects, and many others. This paper describes a three-millimeter-wavelength (W-band, 94 GHz) EPR spectrometer built for a multi-user facility and illustrates with some examples, most of them being disordered systems. One significant example is the oxidized primary reaction center, P ₈₆₅ ⁺ , isolated from the red photosynthetic bacteriaRhodobacter Sphaeroides R-26. The W-band technique applied to both centers isolated from bacteria grown from either deuterated or ordinary growth media allows extraction of the fullg anisotropy in these centers and sets the stage for multifrequency EPR spectroscopy to yield a full analysis of the various contributions to linewidths in these systems.     

Oscillations Do Not Distinguish Between Massive and Tachyonic Neutrinos

It is shown that the hypothesis of tachyonic neutrinos leads to the same oscillations effect as if they were usual massive particles. Therefore, the experimental evidence of neutrino oscillations does not distinguish between massive and tachyonic neutrinos. Thus, in view of the fact that the results of the direct neutrino mass measurements are not decisive, the question about the nature of neutrinos remains still open.     

Intercalating Nucleic Acids Containing Insertions of Naphthalimide

In a study of linker‐length dependence, we evaluated naphthalimide (= 1H‐benzo[de]isoquinoline‐1,3(2H)‐dione) and 4‐bromonaphthalimide as intercalating nucleic acids. We used a vicinal dihydroxy system when incorporating the six different naphthalimide monomers into DNA, and found the minimum linker‐length to be five C‐atoms. With this length of the linker, naphthalimide was discriminating between DNA and RNA – stabilizing DNA, while destabilizing RNA. Furthermore, naphthalimide showed universal base character by hybridizing to the four natural bases with a range as narrow as 1.4°. When compared to pyrene, naphthalimide with the same linker‐length gave significantly higher thermal meltings when hybridized to DNA.     

Rate-equation calculations of the current flow through two-site molecular device and DNA-based junction

Here we present the calculations of incoherent current flowing through the two-site molecular device as well as the DNA-based junction within the rate-equation approach. Selected phenomena of interest are discussed in detail. The structural asymmetry of a two-site molecule results in a rectification effect, which can be neutralized by an asymmetric voltage drop at the molecule-metal contacts due to coupling asymmetry. The results received for the poly(dG)-poly(dC) DNA molecule reveal the coupling-and temperature-independent saturation effect of the current at high voltages, establishing for short chains the inverse square distance dependence. Additionally we document the conductance peak shifting in the direction of higher voltages due to a temperature decrease.     

Sorption properties of sheep wool irradiated by accelerated electron beam

Electron beam (EB) irradiated wool was examined for sorption of chromic ions. Sorption increased with the adsorbed dose non-monotonously, which is a result of the generation of S-oxidized groups, secondary structure variation, and the breaking of the keratin backbone. For a dose of 400 kGy, an increase by 120 % was observed at the cystine dioxide and cysteine acid amounts. Examining sorption of unexposed wool and that irradiated with doses of 25 kGy and 40 kGy for basic, methylene blue (MB), or acidic, pyrogallol red (PR) dyes revealed that such low doses have no effect on the carboxylic or amino groups of keratin. Sorption of MB is independent of the EB treatment and is identical for both samples due to the interaction of MB amino groups with the carboxylic groups of wool; however, the sorption capacity for PR is a function of the EB treatment. The sample irradiated with the dose of 25 kGy showed higher PR sorption than that with the EB dose of 40 kGy, which was equal to that of unexposed wool. While the 25 kGy sample provided more active sites for PR interaction compared with the unexposed one, the 40 kGy sample contained already enough active sites to generate intra- and intermolecular interactions inside wool. Thus, PR adherence to the 40 kGy sample was restricted and comparable to the level of unexposed wool.     

Effect of drying methods on the content of natural pigments and antioxidant capacity in extracts from medicinal plants: a spectroscopic study

Medicinal plants are a significant source of biological active and health protective compounds. Post-harvest treatments can affect, in different ways, the content and biological activity of such compounds. One of the most common post-harvesting methods is drying. In this study, we investigated the effect of drying method on the content of natural pigments (chlorophylls, carotenoids and anthocyanins) and on the antioxidant capacity of two traditionally used herbs, the Melissa officinalis (lemon balm) and the Urtica dioica (stinging nettle) both of them landraces collected from plants grown in Nitra region, West of Slovakia. The freeze-dried samples of both herbs exhibited the highest content of chlorophyll a (7.55 ± 0.13 mg/g dry mass for lemon balm and 9.41 ± 0.17 mg/g dry mass for stinging nettle), chlorophyll b (3.12 ± 0.28 mg/g dry mass for lemon balm and 3.34 ± 0.24 mg/g dry mass for stinging nettle) and carotenoids (2.11 ± 0.24 mg/g dry mass for lemon balm and 2.62 ± 0.06 mg/g dry mass for stinging nettle). The content of chlorophylls and carotenoids correlated with the DPPH antioxidant (radical scavenging) capacity. Higher antioxidant capacity of the lemon balm extracts compared to nettle samples was attributed to the higher content of polyphenol compounds anthocyanins. Despite the higher cost, the freeze drying (lyophilisation) was recommended as the most suitable drying method, mainly for reasons of preserving maximum pigment content and antioxidant capacity.     

Occurrence and Determination of Carotenoids and Polyphenols in Different Paprika Powders from Organic and Conventional Production

Paprika powder is a good source of different carotenoids and polyphenols, which play a key role in preventing certain diseases (some kinds of cancer and cardiovascular diseases). They can also be used as natural food colorants. Organic production is characterized by strict rules, but products obtained in this way contain more bioactive compounds, such as carotenoids and polyphenols. The aim of this study was to measure and identify carotenoids and polyphenols in different paprika samples (sweet, hot, smoked, and chili) obtained by organic and conventional production. Quantitative and qualitative carotenoid and polyphenols analysis showed that the experimental samples contained different concentrations of these compounds.