A study of the properties and composition of stearic acid monolayers on an aqueous subphase containing cadmium ions

Compression isotherms and chemical compositions of stearic acid (HSt) monolayers applied onto an aqueous subphase containing cadmium ions have been studied in a wide pH range. The data obtained have been used to calculate the dependences of surface elasticity E_2.5, change ΔA_2.5 in the surface area per molecule at a constant two-dimensional pressure in the monolayer of 2.5 mN/m, and change Δ|ζ| in the absolute value of the ζ potential of particles formed from the material of a monolayer collapsed on the surfaces of aqueous solutions with the same compositions on the pH of the subphase. The obtained data are in good agreement with each other and unambiguously attest to the dependences of the surface (E_2.5, ΔA_2.5) and electrosurface (Δ|ζ|) characteristics of the monolayers on their chemical composition. This leads us to make the reasonable suggestion that two alternative reactions may occur between cadmium ions and the HSt monolayer with the formation of two salts, CdSt₂ and Cd(OH)St.     

Electron work function in YNi3 − x T x (T = Cu,Fe, Mn; x = 0, 0.5) intermetallics

The electron work function in cast samples and cylindrical compacts of YNi_{3 ? x} T _x (T = Cu, Fe, Mn; x = 0, 0.5) intermetallics is determined using the contact potential difference method. A correlation is found between the electron work function and the electronegativity of elements substituting Ni in the YNi₃ structure.     

Reconstruction and selection of J/ψ → e + e − decays registered by CBM setup in 25 AGeV AuAu collisions

The problem of reconstructing and selecting J/? → e ⁺ e ^? decays registered by the CBM setup in AuAu collisions at 25 AGeV beam energy is considered. The key task in this problem is fast and reliable electron-positron identification using the energy losses of charged particles in the Transition Radiation Detector (TRD). We consider two methods for solving this problem: an artificial neuron network (ANN) and a modified non-parametric goodness-of-fit ω _n ^k criterion. Our analysis shows that both approaches give similar results for the J/? → e ⁺ e ^? yield and the signal-to-background ratio. Compared with the ω _n ^k criterion, the method based on ANN has a number of disadvantages which are discussed in detail. Taking into consideration the very simple software implementation of the ω _n ^k algorithm, it can be used for J/? → e ⁺ e ^? decays selection in a real-time experiment.     

The influence of temperature on narrow I 1 and I 2 lines in the luminescence spectrum of Ni0.6Zn0.4O

The behavior of the luminescence spectrum of solid solution Ni_0.6Zn_0.4O, in which two intense narrow lines were recently discovered, is investigated as a function of temperature. It is shown that the intensity of one of the lines drops in accordance with the Mott law with increasing temperature in the range between 10 and 50 K. The lines experience broadening, and the ratio of their intensities changes. In addition, the lines shift toward lower energies. This shift and broadening of both lines occur differently, suggesting that they are of different nature.     

Alterations of lipoxygenase specificity by targeted substrate modification and site-directed mutagenesis

BACKGROUND: Mammalian lipoxygenases (LOXs) are categorised with respect to their positional specificity of arachidonic acid oxygenation. However, the mechanistic basis for this classification is not well understood. To gain a deeper insight into the structural basis of LOX specificity we determined the reaction characteristics of wild-type and mutant mammalian LOX isoforms with native and synthetic fatty acids substrates. RESULTS: The rabbit 15-LOX is capable of catalysing major 12-lipoxygenation when the volume of the substrate-binding pocket is enlarged. These alterations in the positional specificity can be reversed when bulky residues are introduced at the omega end of the substrate. Simultaneous derivatisation of both ends of fatty acids forces a 15-LOX-catalysed 5-lipoxygenation and this reaction involves an inverse head-to-tail substrate orientation. In contrast, for arachidonic acid 5-lipoxygenation by the human 5-LOX the substrate fatty acid may not be inversely aligned. The positional specificity of this isoenzyme may be related to its voluminous substrate-binding pocket. Site-directed mutagenesis, which leads to a reduction of active site volume, converts the 5-LOX to a 15-lipoxygenating enzyme species. CONCLUSIONS: The positional specificity of LOXs is not an invariant enzyme property but depends on the substrate structure and the volume of the substrate-binding pocket. 15-LOX-catalysed 5-lipoxygenation involves an inverse substrate alignment but this may not be the case for 5-LOXs. Thus, both theories for the mechanistic basis of 5-lipoxygenation (straight and inverse substrate orientation) appear to be correct for different LOX isoforms.     

Erratum to: Several Articles in JETP Letters Published Online First

JETP Letters - An Erratum to this paper has been published: https://doi.org/10.1134/S0021364022330013     

Structure and Properties of SnO2–In2O3–Ag–N Coatings Formed by a Complex Method on Copper

Russian Physics Journal - The aim of this work is to analyze the structure and properties of a coating of the SnO2–In2O3–Ag–N composition formed on copper by a complex method...     

Fine Structure and Fracture Surface of Low-Carbon Steel Welds

Russian Physics Journal - Using the methods of modern physical materials science, the structural phase state, the defect substructure and the fracture surface of low-carbon alloy steel welds formed...     

Glutinoin, a novel antioxidative ellagitannin from Alnus glutinosa cones with glutinoic acid dilactone moiety

The crude aqueous ethanol extract of the cones of Alnus glutinosa (L.) Gaertn. (Betulaceae; black alder, European alder) was obtained and further partitioned between water and various organic phases. The active water and butanol phases were subjected to assay-guided (DPPH) fractionation using repetitive RP HPLC until individual compounds were isolated. Their antioxidative activities, measured as SC?? values, were evaluated. The chemical structures of the isolated compounds were elucidated with the help of mass spectroscopy, (1)H NMR technique, UV spectroscopy, and chemical approaches. One novel ellagitannin, glutinoin (2), along with two known compounds, pedunculagin (1) and praecoxin D (3), were isolated and found to contribute to antioxidative activity of the A. glutinosa cones extract. The activities (SC??) of 1-3 were evaluated as 0.95 (1), 1.00 (2) and 1.01?μg?mL?1 (3). The scavenging effects of glutinoin (2) and praecoxin D (3) were reported for the first time.     

G-Strands

A G-strand is a map g(t,s):?×?→G for a Lie group G that follows from Hamilton’s principle for a certain class of G-invariant Lagrangians. The SO(3)-strand is the G-strand version of the rigid body equation and it may be regarded physically as a continuous spin chain. Here, SO(3) _K -strand dynamics for ellipsoidal rotations is derived as an Euler–Poincaré system for a certain class of variations and recast as a Lie–Poisson system for coadjoint flow with the same Hamiltonian structure as for a perfect complex fluid. For a special Hamiltonian, the SO(3) _K -strand is mapped into a completely integrable generalization of the classical chiral model for the SO(3)-strand. Analogous results are obtained for the Sp(2)-strand. The Sp(2)-strand is the G-strand version of the Sp(2) Bloch–Iserles ordinary differential equation, whose solutions exhibit dynamical sorting. Numerical solutions show nonlinear interactions of coherent wave-like solutions in both cases. Diff(?)-strand equations on the diffeomorphism group G=Diff(?) are also introduced and shown to admit solutions with singular support (e.g., peakons).