pH-Regulated Carbon Dots Fluorescence Sensor Array Detection of Multiple Heavy Metal Ions Under Stepwise Prediction

As a large amount of heavy metals leaches into water sources from industrial effluents, heavy metal pollution has become an important factor affecting water quality. To enable the detection of multiple heavy metals, we constructed a pH-regulation fluorescence sensor array. Firstly, by adding a metal chelating agent as receptor, metal ions and carbon quantum dots (CDs) were connected to distinguish between Cr6+, Fe3+, Fe2+, and Hg2+ ions. Thus, the lack of affinity between the indicator functional groups and the analyte was solved. Secondly, by adjusting the pH environment of the solution system, an economical and simple array sensing platform is established, which effectively simplified the array construction. In this study, the SX-model was used in the field of fluorescence sensor array detection for metal ion recognition. Based on the strategy of stepwise prediction, combined with the classification and concentration models, the bottleneck of the unified model in previous studies was broken. This sensor array demonstrated sensitive detection of four heavy metal ions within a concentration range from 1 to 50 µM, with an accuracy of 95.45%. Moreover, it displayed the ability to efficiently identify binary mixed samples with an accuracy of 95.45%. Furthermore, metal ions in 15 real samples (lake water) were effectively discriminated with 100% accuracy. A chelating agent was used to improve the sensitivity of heavy metal ion detection and eventually led to high-precision prediction using the SX-model.

The genus Ramalina (Ascomycota, Lecanoromycetes, Ramalinaceae) from the Scattered Islands (French Southern and Antarctic Lands), with descriptions of three new species

A systematic survey of lichens was performed in 2019 in four of the five territories constituting the French Scattered Islands (Europa Island, Juan de Nova, Glorioso Islands, and Tromelin) focusing on the genus Ramalina. Species were characterized using morphological (macroscopic and microscopic) features and an accurate chemical profiling method based on high-performance liquid chromatography coupled with diode-array detection and electrospray ionization tandem mass spectrometry (HPLC-DAD-MS). Five species were found in these territories. Two of them, Ramalina dumeticola and R. ovalis, are already known. Three species are introduced here as new to science: Ramalina gloriosensis sp. nov., R. hivertiana sp. nov., and R. marteaui sp. nov. An identification key is provided for the species found in the area and morphologically closely related taxa.

STABILITY INDICATING RP-HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF SIMETHICONE, DOMPERIDONE, MAGALDRATE AND SODIUM ALGINATE: APPLICATION TO SYRUP FORMULATION

A rapid and validated stability indicating RP-HPLC method using isocratic elution and coupled with photodiode array detection was developed for quantifying the content of simethicone, domperidone, magaldrate and sodium alginate in bulk and syrup formulation. The best mobile phase used in this study consisted of 0.1 % orthophosphoric acid/acetonitrile (50/50, V/V) with a flow rate of 0.7 mL min-1. Under optimized conditions used in this study, selected drugs were eluted at 3.301 min (simethicone), 4.293 min (domperidone), 5.220 min (magaldrate) and 6.149 min (sodium alginate) within 12 min run time without any interfering excipients. Peak areas and selected drug content demonstrated excellent linearity (simethicone – 5 to 30 µg mL-1; domiperidone – 2.5 to 15 µg mL-1; magaldrate – 120 to 720 µg mL-1; sodium alginate – 25 to 150 µg mL-1). Percent recovery, which represents accuracy, was 99.12–100.18 % for simethicone, 99.59-100.52 % for domperidone, 99.23-100.25 % for magaldrate and 99.57-100.02 % for sodium alginate. Percent relative standard deviation, which represents precision, was observed in the range of 0.078-0.983 % (simethicone), 0.528-0.861 % (domperidone), 0.278-1.069 % (magaldrate), 0.316-0.572 % (sodium alginate). The developed method displayed favourable accuracy and recovery and was suitable for determining the content of simethicone, domperidone, magaldrate and sodium alginate combination in syrup formulations.

Principles of Gravitational-Wave Detection with Pulsar Timing Arrays

Pulsar timing uses the highly stable pulsar spin period to investigate many astrophysical topics. In particular, pulsar timing arrays make use of a set of extremely well-timed pulsars and their time correlations as a challenging detector of gravitational waves. It turns out that pulsar timing arrays are particularly sensitive to ultra-low-frequency gravitational waves, which makes them complementary to other gravitational-wave detectors. Here, we summarize the basics, focusing especially on supermassive black-hole binaries and cosmic strings, which have the potential to form a stochastic gravitational-wave background in the pulsar timing array detection band, and the scientific goals on this challenging topic. We also briefly outline the recent interesting results of the main pulsar timing array collaborations, which have found strong evidence of a common-spectrum process compatible with a stochastic gravitational-wave background and mention some new perspectives that are particularly interesting in view of the forthcoming radio observatories such as the Five hundred-meter Aperture Spherical Telescope, the MeerKAT telescope, and the Square Kilometer Array.

IDENTIFICATION AND CONTENT OF PHENOLIC COMPOUNDS IN A BUTANOL FRACTION OF EXTRACT FROM THE FLOWERS OF TANACETUM VULGARE

Tanacetum vulgare L. (syn.: Chrysanthemum vulgare (L). Bernh) is a perennial medicinal plant with a Euro-Asian type of habitat. Tansy extracts have a wide biological and pharmacological activity. At the All-Russian Institute of Medicinal and Aromatic Plants, on the basis of the butanol fraction of the T. vulgare flowers extract was developed a drug with high choleretic and anti-inflammatory activity. In this regard, the aim of this work was to study the qualitative composition and quantitative content of phenolic compounds of the butanol fraction, which are supposed to determine its biological activity. For this was obtained a phenolic compounds fraction, isolated from the extract of inflorescences of T. vulgare plants grown on the VILAR experimental plot. High-performance liquid chromatography with diode-array detection in combination with high-resolution mass spectrometry (UPLC-PDA-HRMS) was used for the analysis. Our studies have shown that the butanol fraction of T. vulgare contains 7 phenolic compounds, among which myricetin-3-glucoside was detected for the first time. The content of phenolic compounds reaches 90%, while the main compounds are neochlorogenic, 3,5- and 4,5-dicofeylquinic acids, the proportion of which is 69%. Thus, the obtained data indicate that the pharmacological activity of the drug based on the butanol fraction of the extract from tansy flowers is due to the high content of caffeoylquinic acids.

Identification of histamine in fish and fish products in Poland during 2014–2018

Introduction Histamine is one of the most important and toxic biogenic amines which may be present in food and may cause food poisoning in humans when contained at a high level. It is produced during bacterial decarboxylation of histidine in fish muscles. The aim of the study was to investigate the presence of histamine in fish and fish products available in Poland during 2014–2018. Material and Methods A total of 421 samples of raw (248), smoked (107), canned (50), and marinated fish (16) were analysed by high-performance liquid chromatography with diode array detection. Results Histamine was detected in 14.1% samples of raw fish, 29% of smoked fish, 22% of canned fish and 93.8% of marinated fish in concentrations ranging from 3.4 to 156.4 mg/kg. Content of this amine above 100 mg/kg was found in four samples: raw Atlantic salmon, smoked European sprat and two samples of marinated Atlantic herring. Conclusion The study showed that fish and fish products on the Polish market generally meet the food safety criteria for histamine and are safe for consumers.

Seasonal distribution of multiclass pesticide residues in the surface waters of northwest Croatia

As part of our OPENTOX project, we evaluated the incidence and mass concentrations of multiclass pesticide residues in 23 river/stream water samples collected in urban and agricultural areas of northwest Croatia at various points of the pesticide application season in 2015. The study included 16 compounds of five herbicide classes and seven compounds of three insecticide classes. Pesticide residues were accumulated from water by solid-phase extraction and analysed using high performance liquid chromatography with UV-diode array detection and/or gas chromatography-mass spectrometry. Herbicide residues were more common than the insecticide ones, and, as expected, they peaked in the middle of the application season. Metolachlor showed the highest concentrations and was found in 91 % of all samples, followed by terbuthylazine, found in 70 % of the samples. The highest total mass concentration of detected pesticides was measured in the water samples of the Krapina (3992 ng/L) and Sutla (3455 ng/L) collected in rural areas with intensive agriculture. Our findings strongly speak in favour of continued monitoring of surface waters and possibly extending the list of priority water pollutants.