Prolonged Thermal Relaxation of the Thermosetting Polymers

The rigidity of structures made of polymer composite materials, operated at elevated temperatures, is mainly determined by the residual rigidity of the polymer binder (which is very sensitive to elevated temperatures); therefore, the study of ways to increase the rigidity of polymer materials under heating (including prolonged heating) is relevant. In the previous research, cured thermosetting polymer structure’s non-stability, especially under heating, is determined by its supra-molecular structure domain’s conglomerate character and the high entropy of such structures. The polymer elasticity modeling proved the significance of the entropy factor and layer (EPL) model application. The prolonged heating makes it possible to release adsorptive inter-layer bonds and volatile groups. As a result, the polymer structure is changing, and inner stress relaxation occurs due to this thermo-process, called thermo-relaxation. The present study suggests researching thermo-relaxation’s influence on polymers’ deformability under load and heating. The research results prove the significant polymer structure modification due to thermo-relaxation, with the polymer entropy parameter decreasing, the glassing onset temperature point (Tg) increasing by 1.3–1.7 times, and the modulus of elasticity under heating increasing by 1.5–2 times.

Relevance of the Entropy Factor in Stereoselectivity Control of Asymmetric Photoreactions

Entropy as well as enthalpy factors play substantial roles in various chemical phenomena such as equilibrium and reactions. However, the entropy factors are frequently underestimated in most instances, particularly in synthetic chemistry. In reality, the entropy factor can be in competition with the enthalpy factor or can even be decisive in determining the overall free or activation energy change upon molecular interaction and chemical transformation, particularly where weak interactions in ground and/or excited states are significant. In this account, we overview the importance of the entropy factor in various chemical phenomena in both thermodynamics and kinetics and in the ground and excited states. It is immediately apparent that many diastereo- and enantioselective photoreactions are entropy-controlled. Recent advances on the entropy-control concept in asymmetric photoreactions are further discussed. Understanding the entropy-control concept will pave the way to improve, fine-tune, and even invert the chemo- and stereoselectivity of relevant chemical phenomena.1 Introduction2 Role of Entropy in Supramolecular Interactions3 Selected Examples of Entropy-Driven Thermal Reactions4 Classical Examples of Entropy Control in Photoreactions5 Entropy-Driven Asymmetric Photoreactions6 Advances in Entropy Control7 Perspective

DETERMINATION OF KINETIC PARAMETERS OF THERMODESTRUCTION AND GROUPS OF FIREPROOF EFFICIENCY OF PINE WOOD, MODIFIED BY BORON NITROGEN FLAME RETARDANT

Wood is a combustible material. To reduce combustibility, wood is modified with functional compounds of phosphorus, boron and nitrogen, inoculation of which changes the chemical composition of the surface layer of wood and its structure. The mechanism of action of flame retardants is related to their influence on the energy and entropy characteristics of the thermodestruction process. Considering that boron nitrogen compounds are effective flame retardants and react with wood components under “mild” conditions, the effect of grafting of a borax modifier on the kinetic parameters of wood thermal decomposition is studied. The kinetic parameters (activation energy and preexponent value) are determined by thermal analysis using TGA curves (integral method). A 50 % aqueous solution of monoethanolamine (N→B) trihydroxyborate is used as a modifier; samples of unmodified pine wood are used as controls. The experimental data obtained indicate that the surface modification of pine wood with boron nitrogen fire retardant provides the material with group II fire protection efficiency (modifier consumption-150g/m2). The flame retardant effect of the boron nitrogen modifier is associated with a lower value of the activation energy of its thermal destruction process. The contribution of the entropy factor in reducing the combustibility of modified wood is less expressed. The use of monoethanolamine (N→B) trihydroxyborate as a wood flame retardant is advisable in an oxidizing atmosphere.

Methodological principles of forming multichannel digital communication in the supply chains

Logistics is undergoing a digital transformation to manage material and intangible flows using various digital communication channels. In this regard, it is extremely urgent to develop a backbone and local IT platforms that unite participants in the supply chain to collect and analyze information for making optimal management decisions. The purpose of this study is to substantiate the main methodological principles of the formation of digital communications between participants in the supply chain to create an inter-corporate information and communication system. In preparing the material, such scientific methods as analysis and synthesis, process modeling, process method, and system approach were used. A model for organizing digital communication in the supply chain using the backbone communication IT platform is proposed. The role of digital trust in the organization of inter-corporate digital communication is shown, and the entropy factor is also taken into account when assessing the throughput of communication channels. The result of the study is the formulation and justification of methodological principles for the introduction of multi-channel digital communication, providing not only electronic data exchange between logistics partners, but also reducing the logistic and transaction costs of supply chain participants.

The Stability Study of Thermodynamic Parameters of Sorption of Light Hydrocarbons on Poly [Trimethylsilyl (Propyn-1)] at Different Temperatures

Chromatographic determination of the thermodynamic parameters of sorption for light hydrocarbons retention on a stationary phase based on poly [trimethylsilyl (propyn-1)] (PTMSP) was performed and the effect of column preheating at temperatures up to 260°C on the retention of analytes was investigated. It was shown that heating the column to 130°C does not affect the retention of the analytes. At temperatures above 130°C, the gradual decrease of the retention of analytes on PTMSP stationary phase is observed. The process is non-selective and proceeds at the same extent for all the studied hydrocarbons, regardless of the size and geometry of the molecule. Values of enthalpy and entropy of sorption of light hydrocarbons are determined for the original column and after its aging at 200°C. The enthalpy of sorption of the analytes at the PTMSP phase is practically independent on the heating temperature of the PTMSP phase, whereas the loss of entropy increases after heating. The increase of the entropy factor after the heating of the PTMSP stationary phase is associated with its aging and is confirmed by the construction of compensation functions for treated and untreated columns.

Ubiquitin recognition of BAP1: understanding its enzymatic function

BRCA1-associated protein 1 (BAP1) is a nuclear localizing UCH, having tumor suppressor activity and is widely involved in many crucial cellular processes. BAP1 has garnered attention for its links with cancer, however, the molecular mechanism in the regulation of cancer by BAP1 has not been established. Amongst the four UCHs, only BAP1 and UCHL5 are able to hydrolyze small and large ubiquitin adducts but UCHL5 hydrolyzes only when it is present in the PA700 complex of the proteasome. The ability of BAP1 to cleave large ubiquitin derivatives is because of its relatively longer active-site crossover loop than other UCHs. The mechanism of ubiquitin recognition has not been studied for BAP1. The comparative enzymatic analysis of ubiquitin C-terminal hydrolase L1 (UCHL1), ubiquitin C-terminal hydrolase L3 (UCHL3), ubiquitin C-terminal hydrolase L5 (UCHL5N), and BAP1N has confirmed that enzymatically BAP1 is similar to UCHL5, which corroborates with the bioinformatics analysis done earlier. We have undertaken extensive mutational approaches to gain mechanistic insight into BAP1–ubiquitin interaction. Based on the homology-modeled BAP1 structure, we have identified a few BAP1 residues which possibly play a crucial role in ubiquitin interaction of which a few mutations have been identified in many cancers. Our comparative thermodynamic analysis reveals that BAP1–ubiquitin interaction is majorly driven by entropy factor which is unique amongst UCHs. Our study sheds light on BAP1 interaction with ubiquitin, which will be useful in understanding its enzymatic function.

Ion-Molecular Memory Model. The Problem of Entropy

The final article in a series of works on creation of ion‐molecular models of memory is dedicated to the entropy factor. The authors examine the correlation between information and entropy. They introduce an entropy equivalent in the specificity of memory (by I. Prigozhin). The memory system is considered markedly nonlinear and non‐equilibrium. The article contains a general conclusion to the series of works. The entropy factor is, from the position of bio‐physic‐chemistry, an important aspect of memory, as a higher form of functioning of the organism, including human organism ‐ in the first place. It is possible to allocate to factor the actual memory several types of entropy, instead of one integrated, as for example in the case of the classical thermodynamic processes. Moreover, the thermodynamic entropy, as a defining static processes, virtually ignored in ion‐molecular memory model (Boltzmann entropy). Here more significant is the consideration of the role of information Shannonʹs entropy. And another important point: to evaluate the entropy of systems with non‐equilibrium processes, which undoubtedly applies to the memory, I. Prigozhin proposed to use the sum of the elements of the correlation matrix, the diagonal members which are set in accordance with probability, and extra diagonal ‐ correlations. The authors use it in the estimation of entropic characteristics of ion‐molecular memory model. I.e. on the basis of proposals Prigozhin, the authors introduce entropy equivalent, which corresponds to the provisions of non‐equilibrium thermodynamics and the requirement for orientation changes in two of its components, that allows to estimate the partial contributions of both types of entropy to the total entropy of memory.