“Dormant” inhibitors of urethane type as controllers of temperature modes of styrene polymerization

Urethanes based on a series of monoisocyanates and phenolic inhibitors of styrene radical polymerization, which release the initial phenolic inhibitor at elevated temperatures, were prepared and characterized. Some of these compounds meet the requirements to “dormant” inhibitors: they sharply decelerate thermally initiated high-temperature polymerization of styrene and do not noticeably affect the rate of low-temperature polymerization in the presence of an inhibiting substance. The possibility of preventing uncontrollable emergency situations by adding these compounds to the initial monomer was confirmed experimentally.     

Chemistry of 1,5-diketones: II. Specificity of transformations of polycyclic 1,5-diketones in acid media

2-(1,3-Diaryl-3-oxopropyl)cyclohexan-1-ones underwent carbo-and heterocyclization in a mixture of acetic acid with acetic anhydride in the presence of perchloric acid. The transformation of 2-(1,3-diaryl-3-oxopropyl)cyclohexan-1-ones into 2,4-diaryl-5,6,7,8-tetrahydrochromenylium salts was shown to involve intermediate 2,4-diarylbicyclo[3.3.1]non-2-en-9-ones. The structure of 2,4-diaryl-substituted bicyclo[3.3.1]non-2-en-9-ones and products of their reactions with halogens and hydroxylamine hydrochloride was confirmed by ¹H and ¹³C NMR spectroscopy.     

Bioelectronic Interface Connecting Reversible Logic Gates Based on Enzyme and DNA Reactions

It is believed that connecting biomolecular computation elements in complex networks of communicating molecules may eventually lead to a biocomputer that can be used for diagnostics and/or the cure of physiological and genetic disorders. Here, a bioelectronic interface based on biomolecule‐modified electrodes has been designed to bridge reversible enzymatic logic gates with reversible DNA‐based logic gates. The enzyme‐based Fredkin gate with three input and three output signals was connected to the DNA‐based Feynman gate with two input and two output signals—both representing logically reversible computing elements. In the reversible Fredkin gate, the routing of two data signals between two output channels was controlled by the control signal (third channel). The two data output signals generated by the Fredkin gate were directed toward two electrochemical flow cells, responding to the output signals by releasing DNA molecules that serve as the input signals for the next Feynman logic gate based on the DNA reacting cascade, producing, in turn, two final output signals. The Feynman gate operated as the controlled NOT gate (CNOT), where one of the input channels controlled a NOT operation on another channel. Both logic gates represented a highly sophisticated combination of input‐controlled signal‐routing logic operations, resulting in redirecting chemical signals in different channels and performing orchestrated computing processes. The biomolecular reaction cascade responsible for the signal processing was realized by moving the solution from one reacting cell to another, including the reacting flow cells and electrochemical flow cells, which were organized in a specific network mimicking electronic computing circuitries. The designed system represents the first example of high complexity biocomputing processes integrating enzyme and DNA reactions and performing logically reversible signal processing.     

Influence of isobaric heating of hydrogen bonding in precritical water

IR spectroscopy and statistical mechanic calculations were used to study the influence of isobaric heating (p 250 bar, T 493–633 K) on H-bond distribution in precritical water. As the temperature rises, the intermolecular water H-bond network is much destroyed, and the fractions of H-bonded n-mers are redistributed. At temperatures close to critical, water has a cluster-like structure with prevalence of dimers and trimers.     

Features of ion hydration and ion association in sub- and supercritical aqueous solutions of rubidium bromide

Results of investigations by the integral equation method in the XRISM approximation of features of structure formation in sub- and supercritical 0.5 M aqueous solution of RbBr. As the system passes from the sub- to supercritical state, the tetrahedral network of the solvent is destroyed, which is typical of water and aqueous solutions; thermal dehydration of the cation and anion are also observed. Dehydration is accompanied by contraction of the first hydration sphere of Rb⁺ and extension of the first hydration sphere of Br⁻. Both in sub- and supercritical solutions conditions a minor amount of contact ion pairs is present whose fraction is Higher by 15% compared to that in standard conditions.     

Nonlinear-dispersive shallow water equations on a rotating sphere and conservation laws

Nonlinear dispersive shallow water equations on a sphere are obtained without using the potential flow assumption. Boussinesq-type equations for weakly nonlinear waves over a moving bottom are derived. It is found that the total energy balance holds for all obtained nonlinear dispersive equations on a sphere.     

Hydration of methylamine and methylammonium ion: structural and thermodynamic properties from the data of the integral equation method in the RISM approximation

The structural and thermodynamic properties of hydration of methylamine and methyl-ammonium ion were investigated by the integral equations method in the RISM approximation. According to calculations, the average number of water molecules in the first hydration shell of CH₃ group is 14.4 for aqueous methylamine and 12.7 for aqueous methylammonium solution. The first hydration shells of the NH₂ group of methylamine and the NH₃ ⁺ group of methylammonium ion contain 6.9 and 5.6 water molecules, respectively. The average number of H-bonds formed by the NH₂ group is 2.4 and that formed by the NH₃ ⁺ group is 3. The results obtained show no H-bonding between the nitrogen atom of NH^{3 +} group of methylammonium and water molecules. The hydrogen atom of water participating in the hydrogen bonding with the nitrogen atom of methylamine now is a constituent of the NH₃ ⁺ group of methylammonium ion. The hydration free energies and the ionization constant calculated within the framework of the RISM theory are in good agreement with experimental data.     

Triplet States of Cyanine Dye Dimers

Russian Physics Journal - The results of investigations of the properties of cyanine dye dimers in the triplet state are presented. The formation of dimers is demonstrated as two absorption bands...     

Free polarization decay in media with a short-range dipole-dipole interatomic interaction

The effect that may be exerted by an interatomic dipole-dipole interaction upon optical transient processes in dense resonance media, in particular, free polarization decay, is analyzed. The behavior of the macroscopic polarization after a single-pulse excitation of a dense ensemble of two-level atoms is considered. It is shown that the free polarization signal is of oscillatory nature, with the oscillation frequency varying in time and being dependent on the dipole-dipole interaction constant, the intensity and duration of the exciting pulse, and the detuning of its carrier frequency from the resonance. The free polarization signal decay, which depends on the magnitude and sign of the sum of the detuning of the exciting pulse carrier frequency from the resonance and the Lorentz frequency, may obey either a power or an exponential law. The signal decay rate is determined not only by the inhomogeneous broadening, but also by the ratio of the above parameters.     

THE EFFECT OF ACIDS ON THE INFRARED SPECTRA OF SCHIFF BASES—II. IMINES CONTAINING THE C=C-C=N AND C=C-C=C-C=N UNITS

Abstract— The Fourier-transform infrared spectra of chloroform-d solutions of conjugated imines CH₃CH=CHCH=NCH(CH₃)₂ and CH₃CH₂CH=CHCH=CHCH=NCH(CH₃)₂ and the related protonated species with HCl, HBr, HI, trichloro, dichloro, monobromo and monochloroacetic acids or propionic acid are presented. The effects of conjugation and protonation are examined. The results show that conjugation slightly increases the basicity of the Schiff bases. HCl, HBr and HI protonate the Schiff bases completely. The carboxylic acids protonate partially depending on their p K _a, values. When the Schiff base contains two (or more) C=C bonds conjugated with C=N, the main C=C stretching band undergoes a strong intensification showing that sizeable dipole moment variations occur along the conjugated chain.