Investigation of the microstructure of activated carbons by the small-angle slow neutron scattering method

The porosity characteristics of the SKT-3 activated carbon (both pure and impregnated with a specific impregnator that increases the carbon absorbability to iodine) have been studied using small-angle neutron scattering. It has been established that the impregnation with an impregnator slightly affects the porosity characteristics of the SKT-3 carbon. The average size of the scattering object is estimated as R ～ 500 Å.     

On the update of DIN-2PI spectrometer

The prospects of increasing the resolution of the DIN-2PI spectrometer at initial neutron energies of 50–500 meV are discussed. The spectrometer resolution can be significantly improved using time-of-flight neutron monochromatization supplemented with a monochromator crystal. The application of this combined monochromatization technique makes the dependence that the instrumental resolution has on the duration of the neutron pulse from the IBR-2 reactor insignificant. This update will make it possible to perform experiments with initial neutron energies to several hundreds of meV in the energy-dumping mode, which, in turn, allows one to study condensed media in a wide range of temperatures, including cryogenic.     

Reactivity of C-H bonds in cyclohexanone and 1-tert-butylperoxycyclohexanol toward the tert-butylperoxyl radical

The kinetics of oxygen uptake and the composition of the cyclohexanone oxidation products in the azobisisobutyronitrile-initiated oxidation of cyclohexanone in the presence of tert-butyl hydroperoxide have been investigated by the Howard-Ingold method. The partial rate constants of the reaction of the tert-butylperoxyl radical with the C-H bonds of cyclohexanol and 1-tert-butylperoxycyclohexanole at 333 K have been determined. The carbonyl group of cyclohexanone activates the C-H bonds in the 2- and 6-positions (α) and deactivates the C-H bonds in the 3- and 5-positions (β) compared to the C-H bonds in the 4-position (γ), whose reactivity is similar to that of the methylenic C-H bonds in cyclohexane. Evaluation of the joint effect of the hydroxyl and tert-butylperoxyl groups in 1-tert-butylperoxycyclohexanol suggests a considerable deactivation of the C-H bonds in the 2- and 6-positions (β) and, to a lesser extent, in the 3- and 5-positions (γ).     

Contribution from two types of peroxyl radicals to cyclohexanol oxidation and their reactivity

The oxygen uptake kinetics in the liquid-phase oxidation of cyclohexanol initiated by cumyl peroxide in the presence of inhibitors (ionol and nitrobenzene) has been investigated (373 K, ortho-dichlorobenzene as the solvent). The relative contributions from the hydroperoxyl and α-hydroxycyclohexylperoxyl radicals to chain propagation has been determined. The rate constants for the reactions of these radicals with the alcohol have been determined.     

Conformational Transformations of ε-Caprolactam as an Advantage in the Production of Molecular Complexes Used in Adhesive Technology

The conformations of the ε-caprolactam molecule were calculated using a software package, and three of its conformers were established. It is shown that the conformational change of molecules creates the prerequisites for organizing the nearest contact and strong hydrogen bonds of ε-caprolactam with molecules of other substances. The molecule of ε-caprolactam can be “adapted to a neighbor” to a greater degree, since it can take a different, more advantageous conformation to provide the necessary contact. With the use of ε-caprolactam, molecular complexes have been obtained that have found application in the production of adhesives for rubber–cord systems.     

Studying the nature of the long-flying component of cosmic rays using X-ray emulsion chambers exposed in the Pamirs and Tien Shan

The origin of an excess of hadrons observed in deep homogeneous lead X-ray emulsion chambers (XRECs) at depths of more than 70 radiation length units is analyzed. Preliminary experimental data on the absorption of cosmic-ray hadrons in a two-storied XREC with a large air gap, exposed in the Tien Shan mountains, are presented. The chamber was designed to test the hypothesis that the main source of the excess of dark spots detected on X-ray films deep inside the XREC was substantial growth of the charmed-particle production cross section at energy E_lab ～ 75 TeV. The experimental data obtained using a two-storied REC and in experiments with deep homogeneous XRECs are compared to the results from calculations using the FANSY 1.0 model. The comparison shows qualitative agreement between the experimental and the model data, assuming high values of the charmed-particle production cross section when E_lab ～ 75 TeV in the forward kinematic region with x_F ≥ 0.1.     

Multicolor Caged dSTORM Resolves the Ultrastructure of Synaptic Vesicles in the Brain

The precision of single‐molecule localization‐based super‐resolution microscopy, including dSTORM, critically depends on the number of detected photons per localization. Recently, reductive caging of fluorescent dyes followed by UV‐induced recovery in oxidative buffer systems was used to increase the photon yield and thereby the localization precision in single‐color dSTORM. By screening 39 dyes for their fluorescence caging and recovery kinetics, we identify novel dyes that are suitable for multicolor caged dSTORM. Using a dye pair suited for registration error‐free multicolor dSTORM based on spectral demixing (SD), a multicolor localization precision below 15 nm was achieved. Caged SD‐dSTORM can resolve the ultrastructure of single 40 nm synaptic vesicles in brain sections similar to images obtained by immuno‐electron microscopy, yet with much improved label density in two independent channels.     

On the equilibrium of peroxy radicals in the oxidation of 2-propanol by molecular oxygen

Based on kinetic data, it is demonstrated that the 1-hydroxy-1-methylethylperoxyl and hydroperoxy radicals are at equilibrium in the oxidation of 2-propanol at 323°C initiated by azobisisobutyronitrile. It is shown that the equilibrium of between the peroxy radicals is not disturbed within the covered range of alcohol concentrations. The rate constants of the reaction of the hydroperoxy radical with 2-propanol is determined: k _2.2 = (0.13 ± 0.04) L mol^?1 s^?1.     

The experience of application of isocyanates in glue compositions

The results of a study of the application of blocked and nonblocked polyisocyanates in glues and their influence on the adhesive properties and lifetime of glues are presented.