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The spectroscopic investigation of the binding properties of berberine‐type 9‐aryl‐substituted isoquinolinium derivatives with G‐quadruplex DNA (G4‐DNA) are presented. Photometric titrations show that these ligands bind with high affinity to the telomeric G4‐DNA form 22AG (K=1.0–44×105 M−2). Furthermore, fluorimetric analysis of thermal DNA denaturation (FRET melting) reveals a significant thermal stabilization of G4‐DNA 22AG upon association with the methoxy‐substituted derivatives. As an analytically useful property, the derivatives with a phenyl substituent or with additional electron‐donating groups show a very weak fluorescence intensity, which increased significantly upon G4‐DNA complexation (fluorescence light‐up effect). Additional time‐resolved fluorescence spectroscopy indicated increased fluorescence lifetimes of the DNA‐bound 9‐(4‐methoxyphenyl)‐substituted derivative, when interacting with the quadruplex‐forming strand 22AG. Notably, the changes of the steady‐state and time‐resolved emission properties of the ligand are more pronounced with G4‐DNA than with duplex DNA so that the combination of these complementary methods may be used for the selective G4‐DNA detection. [ABSTRACT FROM AUTHOR]

Small intermountain river basins are most suitable for developing new methods to estimate water balance due to their well-defined catchment boundaries, relatively rapid runoff processes, and accessible landscapes for study. In general terms, dissecting the hydrograph of a small mountain river requires calibration of the flow model against multi-year data sets, including (a) glacier mass balance and snow water content, (b) radiation balance calculation, (c) estimation of the groundwater contribution, and (d) water discharge measurements. The minimum primary data set is limited to the precipitation and temperature distributions at the catchment. This approach postulates that the conditions for the formation of all components of river flow are known in advance. It is reduced to calculating the dynamic balance between precipitation (input part) and runoff, ablation, and evaporation (output part). In practice, accurately accounting for the inflow and outflow components of the balance, as well as the impact of regulating reservoirs, can be a challenging task that requires significant effort and expense, even for the extensively researched catchments. Our studies indicate the potential benefits of an approach based on one-time, but detailed, observations of stable isotope composition, temperature, and water chemistry, in addition to standard datasets. This paper presents the results of the 2022–2023 work conducted in the basin of the small mountain river Ala-Archa, located on the northern slope of the Kyrgyz Range in Tien-Shan, which was chosen as an example due to its well-studied nature. Our approach could identify previously unknown factors of flow formation and assess the time and effectiveness of work in similar conditions. [ABSTRACT FROM AUTHOR]

This scientific article presents the results of studies on the distribution of natural and artificial radionuclides in fish living in the rivers of the northwestern sector of the Arctic zone of the Russian Federation. Fish sampling (about 76 kg in total) was carried out in the White Sea, in the Northern Dvina and Mezen Rivers, and in the Sukhoe Sea Bay of the Arkhangelsk Region, as well as in the rivers of the Nenets Autonomous District: Pesha, Oma, Vizhas, Nes, and Pechora. The results showed the presence of artificial radionuclides Cs-137 and Sr-90 in fish only in the Nes River of the Nenets Autonomous District. The levels of radionuclides in whole bodies perch and pike in the Nes River range from 3.73 to 14.0 Bq/kg wet weight for Cs-137 and less than 3.72 to 23.1 Bq/kg wet weight for Sr-90. In addition to Cs-137 and Sr-90, the presence of the radionuclide K-40, which is the main dose-forming radionuclide, was noted in the fish of all the studied rivers and seas. K-40 activity was in the reached values 138 Bq/kg for whole fish bodies. The only assumption that can explain the presence of artificial radionuclides in the fish of the Nes River is a possible radioactive trace formed as a result of global nuclear tests, including in the Novaya Zemlya archipelago. At the same time, it is noted that the current levels of technogenic radioactivity in fish from the Nes River do not pose a radiological hazard to the local population. [ABSTRACT FROM AUTHOR]

This article is devoted to the study of the impact of the development of the Lomonosov diamond deposit on the pollution of watercourses with trace metals. The high water cut of the exposed rock strata and the presence of groundwater require the constant pumping of wastewater into the filtration fields, and then to the nearby river. This work shows a significant contribution of discharge processes and drainage waters to the trace metal contents in the surface waters of the Zolotitsa river; an increase in the concentrations of Mg, Sr, Zn, Cu, Cd, As, and Se was noted. The seasonal variations of physicochemical parameters, the trace metal contents, as well as the total uranium and U isotope 234U, 238U, and 235U were analysed. Calculations of water quality indices (HMEI, HMPI, and HMTL) and public health risks (HI and CR) revealed a high level of pollution of certain sections of watercourses. Radiological studies of polluted rivers in the area showed a satisfactory situation. The results of this study can provide a basis for the subsequent monitoring of the impact of anthropogenic activities on nearby watercourses in the development of diamond deposits. [ABSTRACT FROM AUTHOR]

The fast intramolecular charge transfer (ICT) accompanied by dual fluorescence from a locally excited (LE) and an ICT state-taking place with N-phenylpyrrole (PP) in the solvent n-propyl cyanide (PrCN) is investigated. The results have shown that the ICT reaction of PP in the investigated alkyl cyanides has a late transition state with a charge distribution similar to that of the ICT state.

The dual fluorescence of 4-(dialkylamino) benzonitriles, the photodegradation of 4-(dimethylamino)benzonitrile (DMABN) and 4-(diethylamino)benzonitrile(DEABN) in a polar solvent was discussed. It was concluded that the photoproduct of these aminobenzonitriles was formed by subtraction of a substituent.

The fast intramolecular charge transfer (ICT) reaction accompained by dual fluorescence from a locally excited (LE) and an ICT state is investigated in alkyl cyanide solvents as a function of temperature for the electron acceptor/donor molecule N-phenylpyrrole (PP). The study stated that the pyrrole and phenyl moieties in the ICT state of PP are coplanar and possess substantial electronic coupling.

The fluorescence spectra of the three 4-aminobenzonitriles DMABN, MABN, and ABN in alkane solvents such as n-hexadecane and 2-methylpentane consist of a single emission band from an LE state. There is no indication for ICT and dual emission in the spectra and the fluorescence decays are accordingly single exponential over the entire temperature range investigated.

The quenching of the locally excited state that occurs with 4-(demethylamino)phenylacetylene in p-dioxane/water mixtures is studied. It is concluded that this quenching does not lead to the appearance of an emission from an intramolecular charge-transfer state.

The dye 3‐(4‐(N,N‐dimethylamino)phenyl)naphtho[1,2‐b]quinolizinium was synthesized by means of a Suzuki–Miyaura reaction in good yield, and its binding properties with duplex DNA, quadruplex DNA (G4‐DNA), RNA, and bovine serum albumin (BSA) were investigated by photometric, fluorimetric and polarimetric titrations and DNA denaturation analysis. The compound intercalates into DNA and RNA, associates in binding site I of BSA, and binds to G4‐DNA by terminal π stacking. The ligand exhibits a fluorescence light‐up effect upon complexation to these biomacromolecules, which is more pronounced and blue shifted in the presence of BSA (Φfl=0.29, λfl=627 nm) than with the nucleic acids (Φfl=0.01–0.05, λfl=725–750 nm). Furthermore, the triple‐exponential fluorescence decay of the probe when bound to biomacromolecules in a cell enables their visualization in this medium and the differential labeling of cellular components. [ABSTRACT FROM AUTHOR]