Alkylation of 6-Polyfluoroalkyl-2-thiouracils with Haloalkanes

Russian Journal of Organic Chemistry - The structure of 6-polyfluoroalkyl-2-thiouracils and reactivity of nucleophilic centers in their molecules were analyzed by quantum chemical calculations....     

Detection of Weak Optical Anisotropy in Strontium Tetraborate Activated by Ytterbium Ions

Optics and Spectroscopy - A technique for detecting and measuring the weak optical anisotropy has been proposed and experimentally implemented. The strontium tetraborate activated by ytterbium...     

On the swelling behavior of poly(N-Isopropylacrylamide) hydrogels exposed to perfluoroalkyl acids

Per- and polyfluoroalkyl substances (PFAS) have rapidly accumulated in the environment due to their widespread use prior to commercial discussion in the early 21st century, and their slow degradation has magnified concerns of their potential toxicity. Monitoring their distribution is, therefore, necessary to evaluate and control their impact on the health of exposed populations. This investigation evaluates the capability of a simple polymeric detection scheme for PFAS based on crosslinked, thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) hydrogels. Surveying swelling perturbations induced by several hydrotropes and comparable hydrocarbon analogs, tetraethylammonium perfluorooctane sulfonate (TPFOS) showed a significantly higher swelling ratio on a mass basis (65.5 ± 8.8 at 15°C) than any of the other analytes tested. Combining swelling with the fluorimetric response of a solvachromatic dye, nile red, revealed the fluorosurfactant to initiate observable aggregation (i.e., its critical aggregation concentration) at 0.05 mM and reach saturation (i.e., its charge neutralization concentration) at 0.5 mM. The fluorosurfactant was found to homogeneously distribute throughout the polymer matrix with energy dispersive X-ray spectroscopy, marking the swelling response as a peculiar nexus of fluorinated interfacial positioning and delocalized electrostatic repulsion. Results from the current study hold promise for exploiting the physiochemical response of PNIPAM to assess TPFOS's concentration.     

Boundary Conditions in the Source of an Electron Beam on the Surface of the Anode Plasma with a Supersonic Ion Flow

Russian Physics Journal - A solution for the one-dimensional Poisson problem for a layer on the surface of a plasma ion emitter is obtained. The case of plasma with a directed ion velocity greater...     

DETERMINATION OF THRESHOLD N-FACTORS OF THE LAMINAR–TURBULENT TRANSITION IN A SUBSONIC BOUNDARY LAYER ON A PROLATE SPHEROID

Journal of Applied Mechanics and Technical Physics - Results of a numerical study of the laminar-turbulent transition in the boundary layer of a prolate spheroid obtained with the use of the ANSYS...     

Satellite Transition of the Resonance Doublet of the Na Atom in a Mixture with CF4

JETP Letters - The excitation spectrum of the resonance luminescence of Na atoms in a mixture with CF4 exhibits a satellite transition corresponding to the simultaneous optical excitation of the...     

Determination of the Yarkovsky Effect Parameter for Asteroids with Small Perihelion Distances

Russian Physics Journal - Results of determining the Yarkovsky effect parameter for all asteroids with small perihelion distances known by January, 2021 are presented. A comparison is performed...     

Infinitely Many Solutions of Nonlocal Kirchhoff-Type Equations via Perturbation Methods

Mathematical Notes - We study the multiplicity of weak solutions to the boundary-value problem $$\begin{alignedat}{2} - M\biggl(\iint_{\mathbb R^{2N}}|u(x)-u(y)|^2 K(x-y)\,d x\,d y\biggr)\mathscr...