Cell model of biporous medium (membrane)

The hydrodynamic permeability of biporous medium (membrane) modeled by the set of porous particles located in the porous medium with other rheological properties is calculated using the cell method. All known boundary conditions on the cell surface, i.e., the Happel, Kuwabara, Kvashnin, and Cunningham boundary conditions, are considered. Significant limiting cases that lead to new or already known results are studied.     

Effect of strong magnetic fields on gas adsorption

The effect of strong pulsed magnetic fields on gas adsorption at dielectric surfaces is demonstrated. We describe the experimental technique and the results indicating a considerable increase in the surface concentration of the adsorbed substance under the action of pulsed magnetic fields with an induction amplitude up to 50 T. The increase in the lifetime and stability of the adsorbed layer is observed. It is shown that the effect of magnetically induced sorption is also manifested in the interaction of iodine vapor with the surface of dielectrics.     

Selection of Conditions for the Dynamic Sorption Preconcentration of a 1,1-Dimethylhydrazine Derivative (4-Nitrobenzaldehyde N,N-Dimethylhydrazone) on Hydrophobized Silica

The type of mass transfer in the sorption of 4-nitrobenzaldehyde N,N-dimethylhydrazone (BDH) on silica chemically modified with hexadecyl groups was determined using the linear model of sorption dynamics, and distribution and mass transfer coefficients of hydrazone were calculated. Optimal conditions of the dynamic sorption preconcentration and desorption of BDH and its subsequent determination by reversed-phase high-performance liquid chromatography were proposed. The detection limit of the compound for preconcentration from a sample of 100 mL was 1 g/L.     

A General Approach Towards Triazole‐Linked Adenosine Diphosphate Ribosylated Peptides and Proteins

Current methods to prepare adenosine diphosphate ribosylated (ADPr) peptides are not generally applicable due to the labile nature of this post‐translational modification and its incompatibility with strong acidic conditions used in standard solid‐phase peptide synthesis. A general strategy is presented to prepare ADPr peptide analogues based on a copper‐catalyzed click reaction between an azide‐modified peptide and an alkyne‐modified ADPr counterpart. The scope of this approach was expanded to proteins by preparing two ubiquitin ADPr analogues carrying the biological relevant α‐glycosidic linkage. Biochemical validation using Legionella effector enzyme SdeA shows that clicked ubiquitin ADPr is well‐tolerated and highlights the potential of this strategy to prepare ADPr proteins.     

Acid-base properties of the active sites of the surface of a skeletal nickel and promoted skeletal nickel catalyst

The acid-base and adsorption properties of the active sites of the surface of a skeletal nickel and promoted nickel catalyst in aqueous solutions were studied by the potentiometric and pKspectroscopy methods. Titanium added as a promoter resulted in an increased number of lines in the pK spectra, which may attest to higher chemical activity of the promoted catalyst. An increase in the pH value of the media was shown to cause a shift in the process equilibria toward the formation of atomic strongly-bound forms of adsorbed hydrogen.     

Analysis of the temperature field of cylindrical flow based on an on-the-average exact solution

The temperature field in a well is constructed on the basis of an on-the-average exact solution, which allows investigation of problems of subterranean thermodynamics and heat and mass transfer. The problem is represented in the form of a sequence of problems of a mixed type, whose solutions give corresponding asymptotic-expansion coefficients and the form of the remainder term and the functions taking into account the presence of the boundary layer, for which analytical solutions are also found. It is shown that the proposed modified asymptotic method provides vanishing of the solution of the averaged problem for the remainder term.     

Behavior of metal complexes of polyacrylic acid in solutions

Metal complexes of polyacrylic acid containing Li, Li, and Cu, or Li and Zn have been studied in saline aqueous solutions using molecular hydrodynamics and light scattering methods. Intrinsic viscosities, weight-average molar masses, hydrodynamic radii, and radii of gyration were obtained. It was shown that the macromolecules of polymetalloacrylates containing divalent metals form small and large supramolecular structures, their dimensions, and composition being dependent on the ionic strength of the solution.